JP3455676B2 - Step detecting device and processing device using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a level difference detecting device used in, for example, a position and area detecting device of an address label of a mail item or a cellophane window (address window) for address display, and a processing device using the same.

[0002]

2. Description of the Related Art Conventionally, for detecting an area of an address label attached to the surface of a letter such as a mail envelope, an image of the letter surface is simply picked up, and it is considered that the address label has an appropriate size based on information about the density of the image. A method of detecting a rectangular area at an appropriate position has been used. Although this method works to some extent, it may be affected if the address label and the letter surface have the same color, or if the letter surface has a picture that looks like a label. is there.

Further, conventionally, a method of detecting a specular reflection light component of illumination light has been used to detect an address window (a transparent paper having a high optical reflectance, for example, a window portion covered with cellophane or paraffin). Has been used. An example thereof can be found in Japanese Examined Patent Publication No. 58-45305 (Patent No. 1377041). This method is of course only for detecting the address window, and it is necessary to separately detect the address label.

In addition to these, there are also steps and unevenness detection methods which are considered to be applicable to the detection of address labels and address windows.
Several types have been known from the past. First, there is a method of reading a shadow or scattered light due to a step edge by oblique illumination. FIG. 38 shows a configuration for reading the level difference on the letter surface by simple oblique illumination. This configuration is installed in a letter stacking and stamping machine that automatically sorts and stamps the front and back of a large number of letters such as envelopes for mail. The purpose is to discriminate between the front and back. A similar configuration is described in Japanese Patent Publication No. 05-7750.

As shown in FIG. 38, a light beam emitted from a halogen lamp is collimated by a collimating lens and forms a letter at a large incident angle (incident angle means an angle formed by a normal line and an incident ray). Irradiate from diagonal direction. The image pickup unit consisting of the image pickup lens and the CCD sensor images the letter from the vertical direction,
The position of the step due to the flap is detected by detecting the shadow generated in the step portion.

However, in such a method of simply performing oblique illumination to detect shadows and scattered light, there is a possibility that the printed contents of the letter surface will be affected. For example, if a black straight line is printed on the front side of the letter, the output obtained by reading this line is the output when the edge of the address label attached to the front side of the letter is read, or the flap on the back side of the letter is read. It may be difficult to distinguish it from the output.

[0007] In addition, as a typical step detecting device using oblique illumination, an SC of Australia shown in FIG. 39 is used.
Product of HRACK SERIAL READER
There is BML3D. This is an edge detector for postage stamps. As shown in FIG. 39, in this device, the illumination light composed of parallel rays illuminates a linear region on the surface to which the stamp is attached at a large angle of incidence from an oblique direction.

Then, the area is read by the line image sensor. The reading area (CCD AREA in the figure) of the line image sensor should be substantially parallel to the vertical side of the stamp. A portion corresponding to each punch hole of the stamp perforation has a shadow on the upper side of the hole due to the effect of oblique illumination, and the lower side of the hole scatters the illumination light and shines brightly.

When this is read by the line image sensor, a signal having a period exactly matching the perforation of the stamp is obtained. By comparing this signal with a reference pattern prepared in advance, the perforated edge of the stamp is detected.

This system improves the accuracy of detection by making maximum use of the fact that the stamp is notched like perforations. Therefore, it cannot be applied when each side is composed of a straight line like an address label.

Another method for detecting surface irregularities is shown in FIG.
The triangulation method shown in 0 is known. The figure shows Shokosha 198.
It is quoted from "Applied Optoelectronics Handbook" published in 1997. In the figure, a laser beam emitted from a semiconductor laser light source is applied to a measured point, and the spot is observed from an oblique direction.

The spot forms an image on the position sensor by the imaging lens. Since the position of the spot image on the position sensor changes depending on the height of the measured point, this can be detected to detect the height of the measured point. Keyence Corporation visible light laser displacement sensor LB-1000
Series (LB-1000 / LB-040) and the like use this method.

In this method, since only one point is measured at a time, in order to measure the uneven shape of a region having a planar spread such as an address label, the detectors are arranged in an array and It is necessary to carry a letter underneath. Therefore, considering that there is a limit to miniaturization of each sensor, it is disadvantageous in terms of resolution and cost.

[0014]

As described above, in the conventional address label / address window detection device and the step detection device by oblique illumination, the change in the reflectance distribution due to the printing on the letter surface or the pattern of the ground causes a step difference. There is a problem that the result of shape reading is affected and the step position cannot be accurately detected.

Further, other methods of edge detection of stamps and unevenness detection by triangulation cannot be applied as they are to the unevenness detection of a region having a planar spread and a linear edge like an address label. There was a problem.

The present invention has been made in view of the above circumstances, and can reduce the influence of the reflectance distribution of the measurement surface due to the printing content of the letter surface and the like, so that the address label or the address window on the letter surface can be reduced. It is an object of the present invention to provide a step detection device capable of detecting the position such as with high accuracy and a processing device using the same.

[0017]

In order to solve the above problems, the present invention provides an illumination means for irradiating an object with illumination light.
In a step detecting device, which comprises an image pickup means for inputting an image of a region illuminated by the illumination light by the illumination means, and which optically detects a step on the object to be inspected by using the illumination means and the image pickup means, The test object surface is divided into a plurality of small irradiation regions each of which is a two-dimensional region, and irradiation light is irradiated to adjacent small irradiation regions from different directions.

That is, in the step detecting apparatus according to the present invention, the surface of the object to be inspected is divided into a plurality of small irradiation areas each consisting of a two-dimensional area, and adjacent small irradiation areas are illuminated from different directions. Light is emitted.

Then, by obtaining an image of the surface of the object to be examined, which is composed of these small irradiation areas, by an image sensor or the like,
The position of the step can be detected with almost no influence of the pattern of the ground of a letter such as a mail to be inspected.

For example, when a letter with an address label is illuminated by parallel rays from an oblique direction, a dark line or a bright line appears in the step portion of the address label depending on the direction of the step due to the effect of the oblique illumination.

When oblique illumination is performed from the higher step side of the step, a shadow is formed on the step portion, and when oblique illumination is performed from the lower step side, a bright line is generated on the step portion. There is no difference in illuminance in the part where there is no step, no matter which side is illuminated.

From the above, the image taken by obliquely illuminating from the right side and the image taken by obliquely illuminating from the left side are the same image except that the brightness is reversed at the step.
Therefore, an image is captured by irradiating illumination light from different directions between adjacent small irradiation areas, and a portion where the illuminance is characteristically changed at the boundary of each small irradiation area in the captured image. By detecting by image processing or the like, it is possible to detect a step portion corresponding to the edge of the address label.

That is, if a dark line in a certain small irradiation area changes into a bright line when it enters the adjacent small irradiation area, the straight line is highly likely to be the edge of the address label.

On the contrary, what was a dark line in a certain small irradiation area is a dark line even in the adjacent small irradiation area, and a discontinuous change in illuminance is seen at the boundary of the small irradiation areas. If not, it is likely to be just a straight black line printed on the writing surface. Therefore, the position of the address label or address window on the letter surface can be detected with high accuracy without being affected by the reflectance distribution due to the printed contents of the letter surface.

[0025]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows the overall structure of a step detecting device according to a first embodiment of the present invention. FIG. 2 is a front view of the step detecting device of FIG. 1 when viewed from the front side. The step detecting device according to the first embodiment is used for, for example, an address label of a mail item, a position of an address display cellophane window (address window), an area detection device, and the like, and an illumination unit, an imaging unit,
It is composed of three parts: an image processing part.

The illumination unit irradiates a letter such as a postal matter with illumination light from both the left and right directions at a large incident angle, and from two illumination devices 310 and 315 which emit a large number of parallel and equally spaced illumination beams, respectively. Composed.

Illumination light 41 emitted from the illumination device 310
0 is from the obliquely upper left direction, and the illumination light 415 emitted from the illuminating device 315 is from the obliquely upper right direction. The linear reading area 220 on the surface of the letter 200 is conveyed in the sub-scanning direction 230 by a conveying device (not shown). Illuminate each simultaneously.

The incident angles of the illumination light 410 and the illumination light 415, that is, the angles formed by the normal to the surface of the letter 200 are equal to each other and are about 70 °. Also, both lighting devices 310, 315
Are equal to each other, and when the system is viewed from directly above, both illuminators 310 and 315 are located symmetrically with respect to the reading area 220. The reading area 220 is a line-shaped area having a longitudinal direction that is perpendicular to the sub-scanning direction 230, that is, parallel to the main-scanning direction, and the image of this line-shaped area constitutes a CCD line image sensor 540 that constitutes an imaging unit.
Read by.

Illumination light 4 applied to the reading area 220
As described above, reference numerals 10 and 415 each include a large number of parallel and evenly spaced illumination beams, and the illumination beam of the illumination light 410 illuminates a number of illumination spots 221.
The illumination beam from illuminates a number of illumination spots 222. If the surface of the letter 200 is flat, the illumination light 41
The linear reading area 220 is illuminated with a uniform illuminance by both 0 and the illumination light 415.

A large number of irradiation spots 221 illuminated by the illumination light 410 and a large number of irradiation spots 222 illuminated by the illumination light 415 are alternately arranged on the linear reading area 220, as shown in FIG. Alternately (22
1, 222, 221, 222, ...).

The letter 200 has a linear reading area 220.
Since the sheet is conveyed in the conveying direction 230 that is orthogonal to the longitudinal direction, the reading area 220 scans the entire surface of the letter 200 from right to left.

Therefore, a large number of irradiation spots 221,
222 is also scanned from right to left over the entire surface of the letter 200, so that the entire surface of the letter 200 is scanned along the loci of the irradiation spots 221 and 222 in the transport direction 23.
It is divided into a number of elongated small irradiation area trajectories parallel to zero.

This state is shown in FIG. That is, letter 2
The captured image of the 00 plane has many small irradiation area loci 321 by the illumination light 310 from the left direction and the illumination light 31 from the right direction.
5 consisting of a large number of small irradiation area trajectories 322 ,
Moreover, the small irradiation area trajectory 321 and the small irradiation area trajectory 32
Every other two will be arranged alternately.

Further, as shown in FIG. 1, an imaging lens 530 is located above the linear reading area 220, and its image is formed on a CCD line image sensor 540 located above it. Image and image. Letter 2
00 is conveyed in the sub-scanning direction 230, so that CC
The D line image sensor 540 captures and outputs an image of the entire letter 200. The image data thus obtained is sent to the image processing unit 100, where the step position information is extracted.

In order to realize the comb-shaped illumination as described above, each of the illumination devices 310 and 315 has a structure as shown in FIG. In FIG. 4, the light emitted from the halogen lamp 101 is collimated by the collimating lens 102.

Further, this parallel light passes through a plurality of slits 103 having holes at equal intervals to form a large number of parallel light beams,
The plurality of irradiation spots 221 or 222 are illuminated in a comb shape from the right side or the left side. By setting the illumination intervals to be equal, it is possible to expect effects such as simplification of alignment between the irradiation spots 221 and 222 and simplification of processing by the image processing unit 100.

An image obtained by using such an illumination unit and an image pickup unit will be described.

The image obtained by the illumination unit / imaging unit as shown in FIG. 1 is the same as that obtained by normal illumination in which the illumination is applied from both sides except for the step portion such as the label edge.

That is, an image simply reflecting the density distribution or reflectance distribution on the surface of the letter 200 can be obtained. However, at the label edge portion, particularly at the edge in the main scanning direction orthogonal to the transport direction 230, due to the effect of oblique illumination (illumination by parallel light with a large incident angle), the output pixel of the output pixel is The values are different.

That is, a bright line or a dark line occurs depending on the illumination direction and the edge direction. Specifically, when oblique illumination is performed from the high step side of the step at the edge portion, a dark line occurs there, and when oblique illumination is performed from the low step side, a bright line occurs there.

Therefore, when the label edge portion exists across the boundary between the adjacent small irradiation area trajectories , the bright line causes a transition to a dark line or the reverse thereof at the boundary between the small irradiation area trajectories , A light-dark discontinuity occurs between the adjacent small irradiation area trajectories . An example of such an image is shown in FIG.

In FIG. 5, the label edges on the left and right of the address label are almost straight lines. Along the straight lines, bright lines and dark lines alternate with a specific period corresponding to the interval of comb-shaped illumination and a specific phase. As a result, an image like a broken line is obtained at the label edge portion.

Presence of a step such as a label edge can be known by detecting the period and phase of this signal.
Similar images are obtained at the right edge and the left edge of the label, but the phase of the signal at the edge portion is inverted. That is, the bright line portion at the right end becomes a dark line at the left end, and the dark line portion at the right end becomes a bright line at the left end. From this, it is also possible to distinguish the right end and the left end of the label.

In order to specifically detect the edge, a method such as pattern matching can be used. For example, the reading density of the CCD line image sensor 540 in the main scanning direction is 1 pixel per 1 mm. Further, in the illumination area 220, one small irradiation area has a width of 2 mm.

That is, the CCD line image sensor 54
If the 1st and 2nd pixels of 0 image the area of the right side illumination, the 3rd and 4th pixels are the area of the left side illumination, and the 5th and 6th pixels are the right side again. .

In this case, when the edge of the label 210 having a width of 4 cm parallel to the main scanning direction comes into the reading area, the width of the label edge portion with respect to this line is 4 cm.
The brightness is reversed every two pixels over the length of. In a portion having no step and other than the edge such as a label, the change does not particularly appear depending on the illumination direction, and an image of the letter surface is simply obtained.

For such an image, a reference pattern elongated in the main scanning direction and having a length of about 1 cm is prepared, and the correlation between the reference pattern and the image is shifted by one pixel in the main scanning direction. By taking this, it is possible to find the component of the signal that changes in synchronization with the change in the illumination direction.

It is rare that a minute density change in the area of about 1 cm on the letter surface such as a character is completely synchronized with a change in the illumination direction in an area sufficiently larger than about 1 cm. By taking the correlation within the region, it is possible to make the influence hardly appear.

Also, such as the background pattern on the 200th letter, 1
The density change, which changes gently over a range larger than about cm, is also eliminated by correlating with the reference pattern. In this way, the edge portion can be detected.

Further, the image processing section 100 also detects a step area due to a label or the like from the position information of the step section detected by the above method. In the output of the imaging unit shown in FIG. 5, broken line patterns corresponding to the arrangement of the small irradiation area loci 321 and 322 appear on the right and left sides of the address label.

As a result, it is detected that these two sides represent the step portion. Further, the length and position of these two sides correspond to each other on the left and right sides. Further, the portion of the left side that is the bright line is the dark line on the right side, and the portion of the left side that is the dark line is the bright line on the right side.

From this, it can be inferred that these two sides are the left side and the right side of a certain rectangular step region, and the rectangular step region can be detected. By performing such processing, the image processing section 100 can detect the area of the address label 210 attached to the letter 200.

In the first embodiment, since the plane to which the label or the like is attached is irradiated from the left and right directions, there is no difference in the output between the right illumination and the left illumination for the step portion extending in the left and right direction. . That is, the label 210 parallel to the sub-scanning direction
The upper and lower sides of can not be detected.

However, in the case of the first embodiment, the letter 20
The purpose is to detect the position and area of the label 210, not each side of the label 210 attached on the 0th surface.

Since the label 210 is rectangular in most cases, if the positions of the right and left sides facing each other are known, the label 210
Even if an edge cannot be detected, the rectangular area occupied by the label 210 can be determined. Therefore, the purpose of the first embodiment is sufficiently satisfied.

Next, the effect of the step detecting device according to the first embodiment will be described. The image obtained by the method of illuminating in a comb shape from two directions is very similar to the one that reflects the density distribution on the surface of the letter 200 obtained by the uniform illumination without the conventional comb structure, but the edge portion of the label. In, the signal is modulated with a signal having a specific period and a specific phase.

By extracting the characteristic signal having the specific period and the specific phase using a method such as pattern matching, it is possible to easily detect only the edge portion of the label or the like without being affected by the density distribution on the surface of the letter 200. It becomes possible to do.

Further, by incorporating the step detecting device according to the first embodiment into, for example, a mail address reading / sorting machine, the area of the address label or the address window where the address is described in the address recognition section can be quickly and accurately determined. It is possible to detect and improve the recognition rate of the address.

As described above, the output image from the image sensor 540 is affected by the pattern of the ground, but the interval between the small irradiation area loci 321 and 322 for the illumination is set to be less affected by the pattern of the ground. By adjusting, this effect can be reduced or eliminated. If the land pattern, the small radiation even be accidentally concentration changes in one place with a boundary of a region locus, the concentration at the boundary of the over many cycles each small irradiation region locus continues to change rare.

Therefore, the intervals between the loci of the small irradiation areas and the size of the reference pattern (how many small irradiation areas the size is).
By selecting appropriately, the influence of the background pattern can be avoided in most cases.

Although the first embodiment of the present invention has been described in detail above, the present invention is not limited to the configuration of this first embodiment. For example, the image processing unit that detects a step is not limited to one that uses pattern matching, but may be any other method that detects a step.

As another configuration of the image processing section, simple detection can be realized by using a filter for converting image data into a time series signal and extracting a frequency component corresponding to the pattern.

As another configuration of the image processing section, there is one based on image tracing. This traces what is considered to be a dark line / bright line from the image output by the image capturing unit, and the output pixel values of these curves are discontinuous in the small irradiation area boundary locus where the illumination direction switches. Check whether it has changed.

If these dark and bright lines are caused by a step, the output pixel value should change discontinuously at the boundary of the locus of the small irradiation area. Therefore, it is used to determine whether this curve is due to a step. It is possible to

By using this structure, the step portion can be detected without any problem even when the step portion is largely deviated from the main scanning direction of the line image sensor 540 or the step portion is a curved line.

Further, as another configuration of the image processing section, there is one using interpolation and difference. This is to separate the pixels in the area of right illumination and the pixels of the area of left illumination from one image output by the image capturing unit into two, and to divide the missing pixels in each image into surrounding pixels. To form a complete right-illuminated image and a complete left-illuminated image.

Then, the difference of each pixel of these two images is taken to obtain another image (difference image). The image obtained by illuminating the whole to the right and the image obtained by illuminating the whole to the left should be exactly the same except for the steps, so the image obtained by interpolating the image of the right illumination It can be said that the same holds approximately for the image obtained by interpolating the image for left illumination.

Therefore, the difference image has a value only at the position of the step, and at other positions, the pixel value is canceled and becomes 0. In this way, the position of the step can be detected. By using this configuration, mounting of the image processing unit becomes very easy and high performance is exhibited.

The method for realizing the illumination unit is not limited to the one using the parallelizing lens 101 and the slit 103 described in FIG. The light transmitted through this slit may be further guided to the irradiation unit by using an imaging lens.

By securing a sufficient depth of focus, this method can increase the parallelism of the illumination light and improve the detection accuracy. Further, a bright part and a dark part may alternately appear in the irradiation part using a lens array or the like. By this method, there is a possibility that the adjustment of the characteristics can be facilitated and the device can be downsized.

Also, when the slit is used,
A highly collimated light source is not necessary. Another example in which comb-shaped illumination is realized by using slits is shown in FIGS. 6 is a front view of the step detecting device, and FIG. 7 is a top view thereof. In this configuration, a halogen lamp (not shown) is used as a light source, and the light emitted from the halogen lamp is guided using a line-type light guide.
Used as 0,415.

The line type light guide is a bundle of a large number of optical fibers, and the end on the emission side is elongated and arranged in a line shape, and is usually used for illuminating a line area. . Comb-shaped illumination is realized by placing comb-shaped slits 430 and 435 as illustrated in the immediate vicinity of the irradiated portion.

Light is emitted from the optical fiber forming the line type light guide with a certain divergence angle, and a typical value of this divergence angle is about 15 degrees on both sides of the central axis. Even if such a light source that is not necessarily parallel light is used, if the divergence angle of this illumination beam is sufficiently small with respect to the ratio of the slit pitch divided by the distance between the slit and the writing surface, the objective is sufficiently achieved. To be done.

In the case of a light source having a spread of 15 degrees from the central axis, it spreads over a width of 0.5 times the unit length on the surface separated by a unit length from the emission port. At this time, the spacing between the slits 430 and 435 and the surface of the letter 200 is required to be at least equal to or less than the pitch of each slit for sufficient modulation. Conversely, the slit 430,
By shortening the distance between 435 and the surface of the letter 200, the requirement for the parallelism of the light source having such a linear arrangement can be relaxed.

Further, the CCD line image sensor 504
When illuminating the reading area, the irradiation directions do not have to be two directions, the left direction and the right direction, and the irradiation may be performed from a plurality of more directions.

In the first embodiment, as described above, the edge parallel to the main scanning direction of the label 210 attached on the surface of the letter 200 can be detected, but the edge parallel to the sub scanning direction cannot be detected. difficult. When the illumination light is applied from two directions, there is one direction in which edge detection is difficult. However, it is possible to avoid this problem by increasing the illumination directions to three or more directions to eliminate the difficult-to-detect directions.

The direction in which the letter 200 is conveyed and the direction of the line image sensor need not necessarily be orthogonal. The direction in which the letter 200 is conveyed (the sub-scanning direction 23
0) and the line image sensor 540 in the main scanning direction may be adjusted to prevent difficulty in detecting the edge direction to be detected.

For example, when the letter 200 is conveyed from right to left, the CCD line image sensor 540 is installed so as to read the line-shaped area from the upper right to the lower left. Then, comb-shaped illumination with a large incident angle is performed from the lower right direction and the lower left direction.

By doing so, not only the side of the address label in the direction perpendicular to the sub-scanning direction 230, but also the side of the address label in the direction parallel to the sub-scanning direction 230 causes dark lines and bright lines. It is possible to detect parallel edges.

The illuminance by the illumination light from each direction when irradiating a plane need not be equal,
They may be different from each other. In such a case, the shading correction processing unit makes a correction.

The illumination light from each direction does not have to have the same property, and for example, the illumination from the upper right may be a halogen lamp light source and the illumination from the upper left may be a fluorescent lamp light source. In these cases, it is possible to save the labor and cost for the adjustment for finely matching the characteristics of the plurality of light sources by performing the correction by the appropriate correction unit.

Although various modifications can be made as described above, these modifications are all included in the present invention without departing from the spirit of the present invention.

(Second Embodiment) Hereinafter, the step detecting device according to the second embodiment is composed of three parts of an illumination unit, an image pickup unit, and an image processing unit, as in the first embodiment described with reference to FIG. The image pickup unit is shown in FIG.
C line image sensor 540 instead of C
A CD area image sensor is used to read, for example, an image on a two-dimensional reading area corresponding to the entire surface of the letter 200 at one time.

The illuminating section divides the two-dimensional reading area into small small irradiation areas like a turtle shell as shown in FIG.
Each area has a large angle of incidence (the angle between the normal and the ray is 70 °
Irradiation light of (about).

At this time, the adjacent small irradiation areas are illuminated from different directions. In each small irradiation area in FIG. 8, the irradiation direction of the small irradiation area is projected on the reading surface by an arrow. The image data captured by the image capturing unit is processed by the image processing unit, and the position data of the step portion is extracted and output.

A method of tracing an image will be described as an example of processing in the image processing section. This traces what is considered to be a dark line / bright line from the image output by the imaging unit, and determines whether the output pixel values of these curves change discontinuously at the boundary of the small irradiation area where the illumination direction switches. I will check.

If these dark lines / bright lines are caused by a step, the output pixel value should change discontinuously at the boundary of the small irradiation area. Therefore, it is used to determine whether or not this curve is due to a step. It is possible.

The step position information extraction method in the image processing section is not limited to the method using the image trace. For example, various things such as one using a neural network, one using pattern matching, and one using interpolation and difference can be considered.

Further, if the direction of illumination (the direction in which the irradiation direction of the illumination light is projected on the reading surface) is set to the four directions of up, down, left and right, the illumination device can be simplified, and there are advantages such as cost reduction. According to the theory of the four-color problem of the map, it is possible to select the illumination direction from four directions so that the adjacent small illuminated areas are illuminated from different directions.

Although various modifications can be made as described above, these modifications are all included in the present invention without departing from the spirit of the present invention.

(Third Embodiment) A step detecting device according to a third embodiment of the present invention includes an illumination unit, an image pickup unit, and an image processing unit.

The third embodiment has substantially the same structure as the structure of FIG. 1 according to the first embodiment, but is characterized in that the small irradiation regions in the illumination section are arranged at unequal intervals. FIG. 9 shows the arrangement of the irradiation spots 221 and 222 in the linear reading area according to this embodiment.

In the reading area 220 of the CCD line image sensor 540, 70 ° from the left direction as shown in the drawing.
A plurality of irradiation spots 221 that emit illumination light with a large incident angle and a plurality of irradiation spots 222 that emit illumination light with a large incident angle of about 70 ° from the right direction are in the longitudinal direction of the reading area 220. Every other one is arranged at unequal intervals.

As in the first embodiment, the letter is picked up by the image pickup unit while being fed in the feeding direction orthogonal to the longitudinal direction of the reading area 220, so that the entire letter is parallel to the feeding direction. Multiple non-uniformly illuminated small area gauges
Will be divided into traces .

By processing this using the image processing unit, the position information of the step is extracted. The processing method used in the first embodiment can also be applied to the processing method used in the image processing unit.

Next, the effect of the step detecting device according to the third embodiment will be described. Various printings may be performed on the surface of the letter 200, and a pattern having periodicity such as a striped pattern is often printed.

One of the problems of the present invention is to suppress the influence of the printed contents on the surface of the letter 200 as much as possible. However, when the small irradiation areas are arranged at equal intervals, the cycle of the pattern having this periodicity is It is conceivable that the image processing unit may be confused when it coincides with the interval of the small irradiation area.

In the third embodiment, the small irradiation areas are arranged at random unequal intervals, so that it is possible to suppress the influence of a pattern having a periodicity which is often used as the print content of the letter 200 surface. Is.

(Fourth Embodiment) In the step detecting apparatus according to the fourth embodiment of the present invention, the illumination light incident on each small irradiation area is composed of illumination light from two or more directions and is adjacent to each other. That is, the composition ratio of the intensity is different in the small irradiation area.

For example, as in the first or third embodiment, a large number of small irradiation area loci 321 and 3 are formed on the surface of the letter 200.
In the case where 22 are alternately arranged, the odd-numbered small irradiation regions are 8000 lx from the right side and 200 from the left side.
It is assumed that the irradiation is 0 lx. The even-numbered small irradiation area is 3000 lx from the right side and 6000 lx from the left side.
It is supposed to have been irradiated with.

In this case, the odd-numbered small irradiation areas are mainly illuminated from the right side, and the even-numbered small irradiation areas are mainly illuminated from the left side, but the illumination light from the left side or the right side is also slightly received. .

As described above, the illumination light incident on each small irradiation region is composed of illumination light from two or more directions,
A configuration in which adjacent small irradiation regions have different intensity composition ratios is also included in the concept of "irradiating adjacent small irradiation regions with illumination light from different directions" that is a feature of the present invention.

Here, similarly to the configuration of FIG. 1, there are illumination lights 410 and 415 from two directions, and the first and second two types of small irradiation area loci 321 and 322 are alternately arranged. In each case, the illumination light 410 and 4
Consider the case where 15 lights are mixed and incident at an arbitrary ratio. Even in such a case, if a certain condition is satisfied, it is possible to detect the step portion by image processing.

For example, when the reading surface is a plane, the small irradiation area locus 321 includes light sources A to L1A and light sources B to L.
Consider a case where the amount of light of 1B enters and the amount of light of light sources A to L2A and from light sources B to L2B enters the small irradiation region trajectory 322.

Then, the output L1 of the small irradiation area trajectory 321
Is L1 = L1A + L1B, and the output L2 of the small irradiation area trajectory 322 is L2 = L2A + L2B. When the reading unit has a step and has a certain inclination, the amount of light from the light source A and the light source B changes at a certain rate, and L1 = αL1A + βL1B L2 = αL2A + βL2B. In this case, if L1A × L2B−L1B × L2A ≠ 0, α and β can be back-calculated from the pixel values, and it is possible to determine whether or not there is a step portion by image processing.

The case has been described above in which there are two types of small irradiation areas having different directions of light sources and different amounts of light coming from the respective light sources. However, the same applies when there are three or more. Such a setting introduces a new degree of freedom to the configuration of the illumination system, and has a feature that the device can be easily configured, such as simplification of stray light processing.

In the fourth embodiment, it is important that the structures of the amounts of light coming from the respective light sources are different between the adjacent small irradiation areas. If this condition is satisfied, what is the ratio of the amounts of light? Even with such a thing, it is possible to detect the step by performing appropriate processing in the image processing unit.

(Fifth Embodiment) A step detecting device according to a fifth embodiment of the present invention illuminates two locus areas 321 and 322 sandwiching the boundary between the small irradiation area loci 321 and 322. It has a configuration in which there are microscopic region loci that are overlapped and illuminated by illumination in any illumination direction.

That is, in the linear reading area 220, the adjacent irradiation spots 221 and 222 partially overlap each other. Further, the other parts have the same configurations as those of the above-described embodiments.

An illuminating section that uniformly illuminates each small irradiation area only from one direction and switches the illuminating direction exactly at the boundary of each small irradiation area is not realistic, and an optical system for realizing such illumination is not available. Would be very expensive.

In the fifth embodiment, the small irradiation area track is used.
By providing such a minute boundary region near the boundary between the traces 321 and 322, the requirement for the optical system is alleviated, which leads to cost reduction.

When the boundary between the small irradiation area loci 321 and 322 is blurred in this way, there may be no obvious discontinuity in the pixel values of curves such as dark lines and bright lines caused by the steps on the surface of the letter 200.

However, even in such a case, the cycle and phase of light and darkness of the curve caused by the step difference are determined by the small irradiation area trajectory 3
There is no change in that the position is aligned with the boundary position of 21, 322, and it is possible to determine that it is a stepped portion by optimizing the processing of the image processing portion.

It should be noted that the structure may be such that there is a minute area on each boundary between the small irradiation area loci 321 and 322 that is not illuminated by illumination in any illumination direction that illuminates the two areas sandwiching the boundary. , The same effect can be expected.

Further, in the image processing section, by simply ignoring the output pixel value of the minute area, the step portion can be detected by almost the same processing as in the case where the minute area does not exist.

(Sixth Embodiment) FIG. 10 shows the arrangement of a step detecting apparatus according to the sixth embodiment of the present invention. This step detecting device is also composed of three parts, an illumination unit, an imaging unit, and an image processing unit, as in the first embodiment, but the illumination unit is the same as in the first embodiment.
Rather than irradiating illumination light simultaneously from the two left and right directions on a line parallel to the transport direction of 0, the two illumination devices placed on a line orthogonal to the transport direction of the letter 200 alternately illuminate the light from the two left and right directions. It is configured to illuminate.

That is, as shown in FIG.
The letter 200 is conveyed from the front side of the paper toward the back side. The light emitted from the light source 610 on the left side of the paper is converted into a plate-shaped parallel light beam by the parallel plate-shaped element 611 and irradiates the line-shaped reading area.

Further, the light emitted from the light source 615 on the right side of the paper is likewise converted into a plate-shaped parallel light beam by the parallel plate-shaped element 612, and irradiates the line-shaped reading area. The illumination capabilities of both light sources 610 and 615 are equal.

Further, the light sources 610 and 615 are formed by a drive circuit including a rectangular wave generator and an inverting circuit so that the letters 20
It is controlled to emit light alternately in synchronism with the transport operation of 0.

As the image pickup section, the line image sensor 5 is used.
40 is used, and the image of the linear reading area is stored on the line image sensor 540 by the imaging lens 530.

This line-shaped reading area is a letter 200.
Is orthogonal to the conveyance direction (sub-scanning direction) of. The illumination direction is switched every time the letter 200 is conveyed by a certain distance, for example, 5 mm.

The direction in which the illumination direction is projected on the surface of the letter 200 coincides with the main scanning direction orthogonal to the conveying direction of the letter 200, or is included in a certain small angle range centered on the main scanning direction.

As shown in FIG. 11, the two light sources 610 and 615 which emit the illumination light from different directions are alternately made to emit light in accordance with the transport operation of the letter 200 and the illumination directions are switched in a time division manner. As described above, the entire writing surface is divided into a large number of small irradiation area loci parallel to the main scanning direction, and the adjacent small irradiation area loci are irradiated with the illumination light from different directions.

The image obtained by such a structure is obtained by rotating the image of FIG. 5 by 90 degrees. That is, as shown in FIG.
Since the small irradiation area locus 321 irradiated with the illumination light from the light source 610 and the small irradiation area locus 322 irradiated with the illumination light from the light source 615 are alternately arranged in a direction orthogonal to the transport direction of The boundary line between the irradiation area loci 321 and 322 appears in the main scanning direction instead of the sub scanning direction, and the wavy line due to the light-dark distribution at the label edge does not appear on the side parallel to the main scanning direction but on the side parallel to the sub scanning direction. appear.

Thus, the dark line or bright line appearing at the label edge is resolved by the line sensor 540 in the main scanning direction by forming the wavy line due to the light-dark distribution at the label edge on the side parallel to the sub-scanning direction. Can be handled with.

Normally, in a line sensor such as a CCD line sensor, even when the main scanning direction and the sub scanning direction have the same resolution, the admixing with adjacent pixels occurs in the sub scanning direction, so that it is effective. The resolution tends to be lower in the sub-scanning direction.

In particular, when it is difficult to sufficiently enhance the illumination capability of the illuminating device, or when the letter conveying speed is very high, it is necessary to reduce the driving frequency of the CCD line sensor below the rated value to solve the problem. Although the resolution does not change, the resolution in the sub-scanning direction deteriorates in proportion to the decrease in frequency.

In the case of letter label detection, even if the detected label position includes an error of several millimeters, it does not cause a big problem. However, if the shadow or bright line appearing at the label edge is overlooked, the label will not be detected. Fail. In such a case, it is important to be able to handle the resolution in the main scanning direction.

(Seventh Embodiment) FIG. 12 shows a step detection processing device according to a seventh embodiment of the present invention.

This step detection processing device is used as a letter conveying / sorting device for performing a sorting processing device for postal items with an address label and the like.
While the paper is being transported, the letter 200 is subjected to processing such as sorting processing.

The letter 200 conveyed by the belt of the conveying mechanism provided in this letter conveying / sorting device is first of all a surface shape reading section including a step detecting device having any one of the structures described in the above embodiments. In 11, the uneven shape due to the step on the surface of the letter 200 is read.

The letter 200 of which the uneven shape has been read by the surface shape reading unit 11 is then conveyed to the image reading unit 12 side, where an image of the characters and the like written on the surface of the letter 200 is picked up.

The label / address window position information extraction unit 113
Based on the uneven shape information read by the surface shape reading unit 111, it is determined whether or not there is a label or address window, and if there is, the position information is output. In the label / address window image information extraction unit 114, based on the image information obtained by the image reading unit 112, the label / address window position information obtained by the label / address window position information extraction unit 113 is used as the label. -Extract the image information of the address window.

The extracted image information is sent to the address information recognition section 115. If there is no label or address window, all image information is sent to the address information recognition unit 115.
The address information recognition unit 115 performs image processing such as analyzing the address information by character recognition and knowledge processing based on the image information of the label / address window portion.

Then, it is determined how the mail should be sorted, and a letter sorting processing command is sent to the letter transport / sorting device 110. Letter transport / sorting device 11
According to this instruction, 0 executes letter distribution processing.

As described above, by using the step detecting device according to the present invention as the step detecting processing device for controlling the letter conveying / sorting device 110, the address can be recognized efficiently and accurately, and the mail can be correctly and quickly sent. It is possible to classify.

The surface shape information of the label / address window obtained by the surface shape reading unit 11 is obtained by the image reading unit 1.
The image of the label / address window portion is not simply cut out from the image obtained by 2, but can be used for any purpose for processing the image information using the surface shape information.

For example, based on the position information of the step area obtained by the surface shape reading unit 111, the probability of being the address writing area is calculated for each area on the surface of the letter 200, and the area portion having the highest probability is sequentially ordered. A processing configuration in which address recognition is tried can be considered.

With such a configuration, even when the extraction of the address label / address window position information fails for the first time, the correct address label / address window position information is extracted from the second time onward, and the probability of successful address recognition increases.

As described above, the surface shape information obtained by the surface shape reading unit 111 is used not only for simply cutting out the image of the address label / address window portion from the image obtained by the image reading unit 112, It may be used for any purpose for processing image information.

The configuration of the step detection processing device in FIG. 12 is not limited to that shown in the figure, and the image reading unit 112 is omitted and the surface shape reading unit 111 is used instead of the image obtained by the image reading unit 112. The image obtained by the image capturing unit may be used as image information.

The image obtained by the image reading unit 112 and the image obtained by the surface shape reading unit 111 are almost the same except for the step portion. Therefore, the image reading unit 112 is omitted in this way, and the surface shape reading unit 111 is omitted.
It is possible to have a configuration in which the function of the image reading unit is provided.
This has the advantage of simplifying the device and reducing costs.

The structure and purpose of the step detection processing device are not limited to those described above. The surface shape reading unit 111 reads the surface shape from the letter 200 to be conveyed, and the flap (postal mail) is read based on the read surface shape. It is also possible to detect the position of the folded back sealing portion of the letter) or the position of a stamp and sort or sort the front and back of the letter 200.

As described above, even if the image reading unit 112 is not provided, it is useful for sorting, sorting, sorting, etc. of mail based on the surface shape information obtained by the surface shape reading unit 111. A step detection processing device that performs processing can be configured.

Although various modifications can be made as described above, all of these modifications are possible unless deviating from the gist of the present invention in which the read image data is processed using the read surface shape data and is effectively utilized. It is included in the present invention.

(Eighth Embodiment) FIG. 13 shows the overall structure of a step detecting device according to an eighth embodiment of the present invention. Further, FIG. 14 is a front view of the step detecting device of FIG. 13 when viewed from the front side. Further, FIG. 15 is a top view of the step detecting device of FIG. 13 when viewed from above. The same parts as those in FIG. 1 will be described with the same reference numerals.

The step detecting device of this embodiment is used for, for example, the address label of a mail item, the position of a cellophane window for address display (address window), and the area detecting device. It consists of three parts.

The lighting unit is the most important part that characterizes this embodiment. The illumination unit irradiates a letter such as a postal matter with illumination light from both left and right directions at a large incident angle, and two illumination devices 310 and 315 that emit an illumination beam from the elongated exit to the linear region 220. and,
Letter 2 to select the incident illumination light for each illuminated point
It is composed of two comb-shaped slits 430 and 435 installed near the 00 plane.

Due to the action of the slit as a light shielding portion, the illumination light 410 emitted from the illumination device 310 is emitted from the illumination device 315 from the obliquely upper left direction.
Reference numeral 15 simultaneously illuminates the staggered positions in the linear reading area 220 on the surface of the letter 200 conveyed in the sub-scanning direction 230 from the obliquely upper right direction. These will be described in detail below.

The left and right illuminating devices 310 and 3 which emit an illuminating beam from the elongated emission port toward the linear region 220.
A line type light guide is used for 15. A line-type light guide is one in which a light beam emitted from a light source such as a halogen lamp is once collected and made incident on an optical fiber bundle that is a bundle of optical fibers, and the output end of the optical fiber bundle is linear (for example, two rows on one straight line). The optical element is suitable for uniformly illuminating a line-shaped region.

The incident angles of the illumination light 410 and the illumination light 415 emitted from this to reach the reading area 220, that is, the letter 2
The angle θ formed by the normal line of the 00 plane is equal to each other, and each θ is about 45 °.

The illumination capacities of the illumination devices 310 and 315 are equal to each other, and when the system is viewed from directly above, the illumination devices 310 and 315 are symmetrical with respect to the reading area 220.

The reading area 220 is a line-shaped area having a longitudinal direction perpendicular to the sub-scanning direction 230, that is, parallel to the main-scanning direction, and the image of this line-shaped area constitutes a CCD line image sensor constituting an image pickup section. Read by 540.

Illumination light 4 applied to the reading area 220
The presence of comb-shaped slits 430 and 435 shown in FIG.

The illumination beam of the illumination light 410 illuminates a number of illumination spots 221 and the illumination beam of the illumination light 415 illuminates a number of illumination spots 222. When the surface of the letter 200 is flat, the illumination light 410 and the illumination light 4 are
Both of 15 adjust so that the linear reading area 220 is illuminated with a uniform illuminance.

As shown in FIG. 19, a large number of irradiation spots 221 illuminated by the illumination light 410 and a large number of irradiation spots 222 illuminated by the illumination light 415 are alternately arranged on the linear reading area 220. Alternately (22
1, 222, 221, 222, ...). FIG. 18 is a diagram for explaining the illumination near the address label of the letter 200.

The letter 200 is a linear reading area 220.
Since the sheet is conveyed in the conveying direction 230 that is orthogonal to the longitudinal direction, the reading area 220 scans the entire surface of the letter 200 from right to left.

Therefore, a large number of irradiation spots 221,
222 is also scanned from right to left over the entire surface of the letter 200, so that the entire surface of the letter 200 is scanned along the loci of the irradiation spots 221 and 222 in the transport direction 23.
It is divided into a number of elongated small irradiation area trajectories parallel to zero.
This state is shown in FIG.

That is, the picked-up image of the surface of the letter 200 shows a large number of small irradiation area loci 3 by the illumination light 310 from the left.
Is composed of a large number of small radiation area path 322 by the illumination light 315 from 21 and to the right, and they small radiation area trajectories
The traces 321 and the small irradiation region loci 322 are arranged alternately every other line.

It is to be noted that the "small irradiation area locus " is a strip area having a width p elongated in the sub-scanning direction on the surface of the letter 200. Further, the term "irradiation spot" is a small area obtained by dividing the reading area of the line sensor into lengths p, and in many cases is an elongated area in the main scanning direction.

[0162] boundary between irradiated boundary spot of the small radiation area locus is in overlapping positions, moving loci of the irradiation spot when scanning an irradiated spot in the sub scanning direction becomes small radiation area trajectory.

In describing the characteristics of the illumination section, the following three parameters p, d and w are important. The slits have a shape as shown in FIG. 15, are installed so that they are staggered left and right, and the pitch thereof is p as shown. Further, as shown in FIG. 14, this slit is installed at a position of a distance d measured from the irradiated portion in the light ray incident direction.

Further, the relationship between the emission direction of the light emitted from the line type light guide and the light intensity is determined by the characteristics of the optical fibers forming the light guide. A divergence width w is used to represent the extent to which the light is emitted with the center axis direction of the optical fiber as the center.

In FIGS. 16 and 17, the radius at which the illuminance drops to 1 / √e of the center point on the plane separated by a unit distance from the optical fiber exit is w. However, the diameter of the optical fiber shall be sufficiently smaller than the unit distance. These three parameters are chosen to satisfy p / wd> 4.

For example, when w = 0.24, p = 5 m
Values such as m and d = 4 mm are possible. As will be described later, the illuminance distribution in the reading area can be determined using these three parameters.

Further, as shown in FIG. 13, an imaging lens 530 is located above the linear reading area 220, and the image is formed on a CCD line image sensor 540 located above it. Image and image.

When the letter 200 is conveyed in the sub-scanning direction 230, the CCD line image sensor 540 captures and outputs an image of the entire letter 200. The image data thus obtained is sent to the image processing unit 100, where the step position information is extracted.

The rough structure of this embodiment has been described above. Here, an image obtained using such an illumination unit and an imaging unit will be described.

The image obtained by the illumination unit / imaging unit as shown in FIG. 13 is illuminated from both sides except the step portions such as the label edges due to the presence of the comb-shaped light shielding plates 430 and 435. It will be the same as with normal lighting.

That is, an image simply reflecting the density distribution or reflectance distribution on the surface of the letter 200 can be obtained. However, the label edge portion, particularly the edge in the main scanning direction orthogonal to the transport direction 230, is output depending on which of the left and right sides is illuminated due to the effect of oblique illumination (effect of illumination by parallel light with a large incident angle). The pixel values are different.

That is, a bright line or a dark line occurs depending on the illumination direction and the edge direction. Specifically, when oblique illumination is performed from the high step side of the step at the edge portion, a dark line occurs there, and when oblique illumination is performed from the low step side, a bright line occurs there.

Therefore, when the label edge exists across the boundary between the adjacent small irradiation area loci , the bright line causes a transition to the dark line or vice versa at the boundary between the small irradiation area trajectories , and Adjacent small irradiation area gauge
A light-dark discontinuity occurs between the traces . An example of such an image is shown in FIG.

In FIG. 20, the label edges on the left and right of the address label are substantially straight lines. Along the straight line, the bright lines and the dark lines alternate with each other in a specific cycle corresponding to the interval of the comb-shaped illumination and a specific phase. As a result, a broken line image is obtained at the label edge portion as shown in the figure.

Presence of a step such as a label edge can be known by detecting the period and phase of this signal.
This is the principle of step detection by this method. Similar images are obtained at the right edge and the left edge of the label, but the phase of the signal at the edge portion is inverted. That is, the bright line portion at the right end becomes a dark line at the left end, and the dark line portion at the right end becomes a bright line at the left end. From this, it is also possible to distinguish the right end and the left end of the label.

An image processing technique such as pattern matching can be used to specifically detect the edge.

As described above, in this embodiment, the step position and the step region are detected by irradiating the irradiation area from the illumination direction which is switched to the left or right for each section of a certain fixed length p.

Such alternate illumination directions are shown in FIG.
Although it is realized by using the comb-shaped slit shown in (1), it has been described above that good detection characteristics can be realized by satisfying the condition of p / wd> 4 with respect to the shape and installation position of this slit.

This condition is that the irradiation spot 2 to be irradiated with the illumination light 410 from the left in the configuration of FIG.
This is necessary in order to prevent the illumination light 415 from the right from entering the 21 as much as possible. This condition will be described in detail below.

First, the illuminance distribution when there is no slit will be described. As shown in FIG. 14, d is the distance between the comb-shaped shading plate measured in the irradiation direction of the illumination light and the irradiated portion (reading area 220).

Further, w is an index showing the spread of light emitted from the optical fiber forming the line type light guide used as the light source. Here, regarding the definition of w, FIG.
6 and FIG.

In FIG. 16, one optical fiber (cross-sectional area ΔA) is placed on the z-axis so that the distance L between its exit and the origin is sufficiently large with respect to the size of the fiber cross section. Then, the irradiated surface is placed on the xy-plane, and x
-Measure the illuminance distribution on the axis. In most cases, this illuminance distribution is

[Equation 1] Can be approximated as For example, in the typical case,
For example, w = 0.24, c = 2.8. Like this, w
Can be defined as the half-width of the illuminance distribution created on a plane separated by a unit distance. Now, when the distance between the optical fiber having a cross-sectional area ΔA having such outgoing light spreading characteristics and the irradiated portion is D, the illuminance of the irradiated portion is

[Equation 2] Becomes Further, when both the width of the emission port and the width of the irradiated portion are sufficiently narrow and the incident direction θ shown in FIG. 14 is θ ≠ 0,
The illuminance of the irradiated portion is simply the above equation multiplied by | cos θ |. From these, the illuminance distribution I on the surface at a distance D from the line fiber having the exit with the width ΔY and the length ΔX
(X, y) is

[Equation 3] Becomes

Consider a case where a slit is further provided. The irradiated surface is an xy-plane, and the optical fiber forming the line-type light guide is oriented parallel to the z-axis, and the center of the emission port is (x, y, z) = (0, 0, D). The longitudinal direction is the x direction.

Further, the slit is in the plane z = d, and 2
np <x <(2n + 1) p is transparent, (2n-1) p <
When x <2np, light is shielded (however, n is an integer). In this way, the illuminance distribution on the irradiation surface obtained by the illumination system composed of the line type light guide and the slit is calculated.

When the line-type light guide outlet is sufficiently long in the x direction (ΔX / p >> 1), translational symmetry is established in the x direction. At this time, when the system is cut along a plane perpendicular to the x-axis, light is emitted from a light source having z = D and a width ΔY with a spread represented by the formula I (x).

If the system is cut along a plane perpendicular to the y-axis, z
= D has an infinitely long light source, and this light source is seen through the slit existing at z = d from the irradiated portion. Since the brightness of the light beam that exits the light source in a certain direction does not change before or after passing through the slit, this state means that there is a light source having a spread represented by the formula I (x) in the transmission part of the slit. Is equivalent to When considering the illuminance on the x-axis within the irradiated surface, the width (d / D) ΔY and the length p are represented by a formula of I (x) on a straight line of z = d and y = 0. It can be calculated as the illuminance when light sources emitted with a spread are arranged at intervals p.

[0187]

[Equation 4] The following function is defined, and the transmittance of the slit having a pitch of 2p (width p) is expressed by using this function, which is H (X / p). Than this,

[Equation 5] Is obtained.

According to the equation obtained here, the shape of the illuminance distribution I (x, y = 0) in the reading section is determined by the coefficient p / w.
It can be seen that it is determined by d (specifically, I
It also depends on the functional form of (x). In this case, exp {-|
x | c / 2}). The integral of the above equation is the same as the integral of exp {| x | c / 2} in the integral range of the length p / wd that appears at every certain interval 2p / wd. exp {|
When the peak at the center of x | c / 2} is located at the center of this integration range, the above equation takes the maximum value Imax (p / wd).
Further, when the peak at the center of exp {| x | c / 2} is located at the center of the gap in this integration range, the above equation is the minimum value Ima.
Take x (p / wd).

From this, the maximum value of I (x, y = 0) is e
xp {-| x | c / 2} is the case where x / p = + 1/2, which is to integrate near the center, and the minimum value is x / p = -1.
It is / 2.

However, the width of the integration range is exp {| x
When it is about 1/3 of the full width of | c / 2}, ex
The contribution of the peripheral part of p {| x | c / 2} becomes larger than that of the central part, and the maximum value and the minimum value may be interchanged. When the width of the integration range is sufficiently larger than the width of exp {| x | c / 2},

[Equation 6] Next to

[Equation 7] Becomes At this time, the difference between the maximum value and the minimum value is Imax (∞)
Therefore, the "modulation degree" can be defined with reference to this value.
That is, the illuminance due to the illumination light from the left is IL (x, p / w
d), when the illuminance due to the illumination light from the right direction is IR (x, p / wd), there is a relation of IR (x, p / wd) = Imax (∞) −IL (x, p / wd). . Using these, | IL (x, p / wd) −IR (x,
p / wd) | / Imax (∞) is defined as the modulation factor at the point x. In particular, the modulation degree at x = ± p / 2 at which IL (x, p / wd) or IR (x, p / wd) takes the maximum value or the minimum value is simply referred to as “modulation degree”. That is, the value obtained by dividing the difference between the maximum illuminance and the minimum illuminance when the slit is formed by this reference illuminance is the “modulation degree”.

As described above, the "modulation degree" of the illuminance of the illuminated area by the comb-shaped slit is determined only by p / wd.
When p / wd is small, the slit pattern is completely blurred on the illuminated surface, and a sufficient "modulation degree" cannot be obtained. Therefore, there is a problem in detecting a step. p / w
If d is sufficiently large, the slit pattern is projected onto the illuminated surface, and a sufficient “modulation degree” can be obtained.

FIG. 21 shows a graph of "modulation degree" with respect to the value of p / wd. With reference to this, the “modulation degree” of comb-shaped illumination, that is, the normalized difference in illuminance between the central portions of adjacent small irradiation regions is 0 at p / wd = 1.1. That is, when p / wd> 1.1 is not satisfied, it is not possible to detect the level difference by capturing the characteristic pattern according to the present embodiment. More practically, it is preferable that the “modulation degree” is almost 100% because the illumination light can be effectively used.

Referring again to FIG. 21, it can be said that p / wd is sufficiently large in this sense if p / wd> 4.

Based on the above calculation, the illuminance distribution in the line-shaped reading area 220 when p, d and w take respective values was calculated. FIG. 22 is a diagram showing the state of the illuminance distribution when p / wd = 1. In this case, the pitch of the slits is too narrow, the distance between the slits and the reading area is too wide, or the directivity of the illumination lights 410 and 415 is insufficient, so that the comb-shaped pattern is completely blurred. Light from both left and right directions is mixed in the entire reading area.

In this state, the level difference cannot be detected in the almost same state as illumination with a light source having a half light intensity from the left and right without a comb-shaped slit. Figure 23 shows p / w
The figure showing the mode of illuminance distribution when d = 2 is shown. In this case, the “modulation degree” is about 55%. Reading area 22
Since the illumination light is applied from both left and right directions at any position within 0, the contrast of the dark line or the bright line in the step portion is low. Therefore, although it is possible to detect a step,
The “modulation degree” is considerably reduced compared to the maximum value. P in FIG.
The figure showing the mode of illuminance distribution when / wd = 4 is shown.

In this case, the “modulation degree” is almost 100%, and the light from the left and right directions is sufficiently separated near the center point of each small irradiation area. At this time, it is possible to detect the position of the step region (address label) with a resolution of p in the main scanning direction. FIG. 25 shows a diagram showing the state of the illuminance distribution when p / wd = 8. In this state, it is possible to sufficiently distinguish the boundary portion of the small irradiation area.

Regarding the determination of the threshold value of 4 for p / wd, a little supplement will be made. As described above, the threshold value of 4 is determined so that the difference in illuminance between the central portions of the adjacent small irradiation areas is sufficiently expressed. A supplementary explanation will be given that the criteria are set by focusing only on the central part.

When the illumination as in the present embodiment is actually performed, an image as shown in FIG. 20 is obtained, and the processing for detecting the step area from such an image is performed by image processing. When the target step area is a mailing address label, the processing content can be considerably simplified as compared with the case where a general step area is detected. One reason is that such an address label is almost rectangular and the edges of the label are almost linear, so that the processing is simple compared to the case of detecting a general shape.

Another reason is that the required accuracy of position detection is gradual because the size of the label is on the order of several cm, and the address area is limited to shorten the processing time of address recognition and to avoid erroneous recognition. This is because an accuracy of about several mm or less is not often required for the purpose.

When the method of this embodiment is used, it is necessary that the illuminance distribution modulation degree at least near the center of the small irradiation area is sufficient. However, the degree of modulation in the vicinity of the small irradiation area boundary does not necessarily need to be high (that is, it may be blurred), and at this time, the position detection accuracy of the step area is about p in the main scanning direction.

In order to obtain the detection accuracy of several mm or less, the pitch p of the comb-shaped illumination may be several mm or less. Even if the illumination pattern near the small irradiation area boundary is blurred, Houg
Applying a powerful straight line extraction algorithm such as h conversion,
It is possible to specify the position of the label edge with an accuracy of about p only from the pixel data near the center of the small irradiation area.

That is, in order to obtain the required accuracy of about p, the "modulation degree" of the central portion of the small irradiation area is sufficient. For this purpose, p / wd> 4 as described above. Good.

Next, the effect of the step detecting device according to the present embodiment will be explained. In this embodiment, special illumination is performed by using a comb-shaped slit, and thereby a step is detected with high accuracy and high accuracy.

The image obtained by the method of the present invention is very similar to the one obtained by the conventional uniform illumination without the comb structure, which reflects the density distribution of the writing surface, but at the edge portion of the label. The signal is modulated with a signal having a specific cycle and a specific phase. Therefore, it is possible not only to extract information for detecting a step from the obtained image, but also to use the obtained image for recognition of the characters printed on the label.

The illuminating device according to the present invention can be easily realized by installing a comb-shaped light-shielding plate according to the conditions described in the claims without using a light source with a high degree of parallelism. Comb-shaped slits can be manufactured at very low cost and are highly effective in detecting steps.

If the step detecting device according to the present embodiment is incorporated into a mail address reading / sorting machine or the like, the address recognition section can quickly and accurately detect the area of the address label or the address window where the address is described. It is possible to exert synergistic effects such as improving the recognition rate of addresses and the processing speed. In most cases, a letter image reading device is originally incorporated in a mail address reading / sorting machine.

Therefore, it is possible to add a step detecting function in addition to the original function at the cost of simply installing the comb-shaped light shielding plate near the reading area.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the configuration of this embodiment. For example, with respect to the resolution of the CCD line sensor, at least 100 μm resolution is required for detecting a step portion in the sub-scanning direction. But,
Step detection is possible even if the resolution in the main scanning direction is not so high.

However, the resolution in the main scanning direction is 100 μm.
Depending on the degree, there is a possibility that the acquired image can be shared with the character recognition. The level difference can be detected by selecting one point or several points for each small irradiation area and reducing the information amount in the main scanning direction.

Line illumination and line reading area 200
When a comb-shaped shading plate (slit) is placed between the two, the illuminance pattern of the line-shaped reading area is determined by the shape of a part of the comb-shaped shading plate.

That is, in FIG. 26, a ray of light emitted from the line illumination to reach the line-shaped reading area is in two planes extending in the 45 ° oblique direction to the left and right of the line-shaped reading area (illumination light 410 or 415 in FIG. 26). Is almost included in the plane including).

Therefore, what is important for the shape of the light shielding plate is the shape of the portion where the light shielding plate intersects these two planes. If the light-shielding portions and the light-transmitting portions are arranged in the same manner on the straight line portions 440 and 445 shown in FIG. 26,
The illuminance pattern of the linear reading area is the same regardless of the shape of the other portions. Therefore, the shading plate is shown in FIG.
The same effect can be obtained by using the one as shown in FIG. 5 or the one as shown in FIG.

Further, since the light shielding plate should not interfere with the reading of the reading area by the image pickup section, a gap 450 is required near the reading area. However, the image information of the entire reading area is not necessary for detecting the step,
If there is information about one or several points in the small irradiation area, it is possible to detect a step.

Therefore, the shape of the slit may be such that a light shielding part is attached only to a necessary part and they are connected by a thin wire 500 as shown in FIG. When the wire portion is near the boundary of the small irradiation area, the small irradiation area boundary portion originally has a blurred illuminance pattern and cannot be used for step detection, so in many cases, it is not a problem.

Further, the shape of the comb-shaped light-shielding plate is not limited to the one in which the width of the light-shielding portion is equal to that of the transmitting portion. For any one of the light-shielding portions, if the width p satisfies p / wd> 4, the shadow of that portion appears in the reading area with a “modulation degree” of 100%. Further, if any one of the transmissive portions has a width p satisfying p / wd> 4, the shape of that portion appears in the reading area with a “modulation degree” of 100%. Therefore, the read image of that portion can be used for step detection, and such an image is also included in the present invention.

The incident angles of the left and right illumination lights do not necessarily have to be the same.

Although various modifications can be made as described above, these modifications are all included in the present invention without departing from the spirit of the present invention.

(Ninth Embodiment) FIG. 13 shows the overall structure of a step detecting device according to a ninth embodiment of the present invention. Further, FIG. 14 is a front view of the step detecting device of FIG. 13 when viewed from the front side. Further, FIG. 15 is a top view of the step detecting device of FIG. 13 when viewed from above. The step detecting device of the present embodiment is used for, for example, an address label of a postal matter, a position of an address display cellophane window (address window), a region detecting device, and the like, and includes an illumination unit, an imaging unit, and an image processing unit. Composed of parts.

The illumination unit is the most important part that characterizes this embodiment. The illumination unit irradiates a letter such as a postal matter with illumination light from both left and right directions at a large incident angle, and two illumination devices 310 and 315 that emit an illumination beam from the elongated exit to the linear region 220. and,
Letter 2 to select the incident illumination light for each illuminated point
It is composed of two comb-shaped slits 430 and 435 installed near the 00 plane.

Due to the action of the slit as a light-shielding portion, the illumination light 410 emitted from the illumination device 310 is emitted from the illumination device 315 from the obliquely upper left direction.
Reference numeral 15 simultaneously illuminates the staggered positions in the linear reading area 220 on the surface of the letter 200 conveyed in the sub-scanning direction 230 from the obliquely upper right direction. These will be described in detail below.

The left and right illuminating devices 310 and 3 which emit an illuminating beam from the elongated emission port toward the linear region 220.
A line type light guide is used for 15. A line-type light guide is one in which a light beam emitted from a light source such as a halogen lamp is once collected and made incident on an optical fiber bundle that is a bundle of optical fibers, and the output end of the optical fiber bundle is linear (for example, two lines on one straight line). The optical element is suitable for uniformly illuminating a line-shaped region.

Incident angles of the illumination light 410 and the illumination light 415 emitted from this to reach the reading area 220, that is, the letter 2
The angle θ formed by the normal line of the 00 plane is equal to each other, and each θ is about 45 °.

Further, the illumination capabilities of the two illumination devices 310 and 315 are equal to each other, and when the system is viewed from directly above, the illumination devices 310 and 315 are in symmetrical positions with respect to the reading area 220.

The reading area 220 is a line-shaped area having a longitudinal direction perpendicular to the sub-scanning direction 230, that is, parallel to the main-scanning direction, and the image of this line-shaped area constitutes a CCD line image sensor which constitutes an image pickup section. Read by 540.

Illumination light 4 applied to the reading area 220
Due to the presence of the comb-shaped slits 430 and 435 shown in FIG.

The illumination beam of the illumination light 410 illuminates a number of illumination spots 221 and the illumination beam of the illumination light 415 illuminates a number of illumination spots 222. When the surface of the letter 200 is flat, the illumination light 410 and the illumination light 4 are
Both of 15 adjust so that the linear reading area 220 is illuminated with a uniform illuminance.

As shown in FIG. 19, a large number of irradiation spots 221 illuminated by the illumination light 410 and a large number of irradiation spots 222 illuminated by the illumination light 415 are alternately arranged on the linear reading area 220. Alternately (22
1, 222, 221, 222, ...).

The letter 200 is a linear reading area 220.
Since the sheet is conveyed in the conveying direction 230 that is orthogonal to the longitudinal direction, the reading area 220 scans the entire surface of the letter 200 from right to left.

Therefore, a large number of irradiation spots 221,
222 is also scanned from right to left over the entire surface of the letter 200, so that the entire surface of the letter 200 is scanned along the loci of the irradiation spots 221 and 222 in the transport direction 23.
It is divided into a large number of elongated irradiation areas parallel to zero. This state is shown in FIG.

That is, the picked-up image of the surface of the letter 200 shows a large number of small irradiation area loci 3 by the illumination light 310 from the left direction.
Is composed of a large number of small radiation area path 322 by the illumination light 315 from 21 and to the right, and they small radiation area trajectories
The traces 321 and the small irradiation region loci 322 are arranged alternately every other line.

It is to be noted that the "small irradiation area" here is a strip area having a width p which is elongated in the sub-scanning direction on the surface of the letter 200. Further, the term "irradiation spot" is a small area obtained by dividing the reading area of the line sensor into lengths p, and in many cases is an elongated area in the main scanning direction.

The boundary of the small irradiation area and the boundary of the irradiation spot are located at the overlapping position, and the locus of movement of each irradiation spot when the irradiation spot is scanned in the sub-scanning direction is the small irradiation area.

In describing the characteristics of the illumination section, the following three parameters of p, d and w are important. The slits have a shape as shown in FIG. 15, are installed so that they are staggered left and right, and the pitch thereof is p as shown. Further, as shown in FIG. 14, this slit is installed at a position of a distance d measured from the irradiated portion in the light ray incident direction.

The relationship between the emission direction of the light emitted from the line type light guide and the light intensity is determined by the characteristics of the optical fibers constituting the light guide. The spread width w is used to represent the extent to which light is emitted with the center axis direction of the optical fiber as the center.

In FIGS. 16 and 17, let w be the radius at which the illuminance drops to 1 / √e of the center point on a plane that is a unit distance away from the optical fiber outlet. However, the diameter of the optical fiber shall be sufficiently smaller than the unit distance. These three parameters are chosen to satisfy p / wd> 8. For example, when w = 0.24, p = 5 m
Values such as m and d = 4 mm are possible. As will be described later, the illuminance distribution in the reading area can be determined using these three parameters.

As shown in FIG. 13, an imaging lens 530 is located above the linear reading area 220, and the image is formed on a CCD line image sensor 540 located above it. Image and image. Letter 2
00 is conveyed in the sub-scanning direction 230, so that CC
The D line image sensor 540 captures and outputs an image of the entire letter 200. The image data obtained in this way is
The step position information is sent to the image processing unit 100, where the step position information is extracted.

The rough structure of this embodiment has been described above. Here, an image obtained using such an illumination unit and an imaging unit will be described.

The image obtained by the illumination unit / imaging unit as shown in FIG. 13 is illuminated from both sides with respect to the portion excluding the stepped portion such as the label edge (due to the presence of the comb-shaped shading plates 430 and 435). It will be the same as with normal lighting.

That is, an image that simply reflects the density distribution or reflectance distribution on the surface of the letter 200 is obtained. However, the label edge portion, particularly the edge in the main scanning direction orthogonal to the transport direction 230, is output depending on which of the left and right sides is illuminated due to the effect of oblique illumination (effect of illumination by parallel light with a large incident angle). The pixel values are different.

That is, a bright line or a dark line occurs depending on the illumination direction and the edge direction. Specifically, when oblique illumination is performed from the high step side of the step at the edge portion, a dark line occurs there, and when oblique illumination is performed from the low step side, a bright line occurs there.

Therefore, when the label edge exists across the boundary between the adjacent small irradiation areas, the bright line makes a transition to the dark line or vice versa at the boundary between the small irradiation areas, and the label edges are adjacent to each other. A light-dark discontinuity occurs between the small irradiation areas. An example of such an image is shown in FIG.

In FIG. 20, the label edges on the left and right of the address label are substantially straight lines. Along the straight line, the bright lines and the dark lines alternate with each other in a specific cycle corresponding to the interval of the comb-shaped illumination and a specific phase.

As a result, a broken line image is obtained at the label edge portion as shown in the figure. The presence of a step such as a label edge can be known by detecting the period and phase of this signal.

This is the principle of level difference detection by this method. Similar images are obtained at the right edge and the left edge of the label, but the phase of the signal at the edge portion is inverted.
That is, the bright line portion at the right end becomes a dark line at the left end, and the dark line portion at the right end becomes a bright line at the left end. From this, it is also possible to distinguish the right end and the left end of the label.

To detect the edge specifically, an image processing technique such as pattern matching can be used.

As described above, in this embodiment, the step position and the step region are detected by irradiating the irradiation area from the illumination direction which is switched to the left or the right for each section of a certain fixed length p.

Such alternate illumination directions are shown in FIG.
Although it is realized by using the comb-shaped slit shown in FIG. 3, it has been described above that good detection characteristics can be realized by satisfying the condition of p / wd> 8 regarding the shape and installation position of this slit.

This condition is that the irradiation spot 2 to be irradiated with the illumination light 410 from the left in the configuration of FIG.
It is necessary in order to avoid that the illumination light 415 from the right gets into the light source 21, etc. as much as possible. This condition will be described in detail below.

First, the illuminance distribution when there is no slit will be described. As shown in FIG. 14, d is the distance between the comb-shaped shading plate measured in the irradiation direction of the illumination light and the irradiated portion (reading area 220).

[0250] Further, w is an index showing the spread of light emitted from the optical fiber forming the line type light guide used as the light source. Here, regarding the definition of w, FIG.
6 and FIG. In FIG. 16, 1
This optical fiber (cross-sectional area ΔA) is placed on the z-axis so that the distance L between its exit and the origin is sufficiently large with respect to the size of the fiber cross section. Then, the irradiated surface is placed on the xy-plane, and the illuminance distribution on the x-axis is measured. In most cases, this illuminance distribution is

[Equation 8] Can be approximated as For example, in the typical case,
For example, w = 0.24, c = 2.8.

As described above, w can be defined as the half width of the illuminance distribution formed on a plane separated by a unit distance. Now, when the distance between the optical fiber having a cross-sectional area ΔA having such outgoing light spreading characteristics and the irradiated portion is D, the illuminance of the irradiated portion is

[Equation 9] Becomes

Further, when both the width of the emission port and the width of the irradiated portion are sufficiently narrow and the incident direction θ shown in FIG. 14 is θ ≠ 0, the illuminance of the irradiated portion is simply multiplied by | cos θ | It becomes a thing. From these, the illuminance distribution I (x, y) on the surface separated by the distance D from the line fiber having the exit of width ΔY and length ΔX is

[Equation 10] Becomes

Consider a case where a slit is further provided. The irradiated surface is an xy-plane, and the optical fiber forming the line-type light guide is oriented parallel to the z-axis, and the center of the emission port is (x, y, z) = (0, 0, D). The longitudinal direction is the x direction.

Further, the slit is in the plane z = d, and 2
np <x <(2n + 1) p is transparent, (2n-1) p <
When x <2np, light is shielded (however, n is an integer). In this way, the illuminance distribution on the irradiation surface obtained by the illumination system composed of the line type light guide and the slit is calculated.

When the line type light guide emission port is sufficiently long in the x direction (ΔX / p >> 1), translational symmetry is established in the x direction. At this time, when the system is cut along a plane perpendicular to the x-axis, light is emitted from a light source having z = D and a width ΔY with a spread represented by the formula I (x).

When the system is cut along a plane perpendicular to the y axis, z
= D has an infinitely long light source, and this light source is seen through the slit existing at z = d from the irradiated portion. Since the brightness of the light beam that exits the light source in a certain direction does not change before or after passing through the slit, this state means that there is a light source having a spread represented by the formula I (x) in the transmission part of the slit. Is equivalent to

When considering the illuminance on the x-axis within the irradiated surface, the width (d / D) Δ is drawn on the straight line of z = d and y = 0.
It can be calculated as the illuminance in the case where the light sources that are Y and have the length p and are emitted with the spread represented by the expression I (x) are arranged at intervals p.

[0258]

[Equation 11] The following function is defined, and the transmittance of the slit having a pitch of 2p (width p) is expressed by using this function, which is H (X / p). Than this,

[Equation 12] Is obtained.

According to the equation obtained here, it is understood that the illuminance distribution I (x, y = 0) in the reading section is determined by the coefficient p / wd (specifically, the functional form of I (x). Also depends on.

In this case, exp {-| x | c / 2}). In the integration of the above equation, exp {| x | c / 2} is set at a certain interval 2p
This is the same as integrating in the integration range of the length p / wd that appears for each / wd.

The illuminance pattern of the reading area is p / wd
The larger the value of, the closer to the square wave shape. This illuminance pattern is as shown in FIGS. 24 and 25, for example. The illuminance pattern due to the contribution from the right direction and the illuminance pattern due to the contribution from the left direction are exactly 180 degrees out of phase with each other.

In order to clearly recognize the step portion, it is better that the difference between the illumination light from the right direction and the illumination light from the left direction is large, that is, the modulation degree is large. Here, the modulation factor at a certain point x refers to a value obtained by dividing the difference in illuminance by the left and right illumination lights by the sum of the illuminance by the left and right illumination lights.

In the present invention, it is determined whether or not there is a step by grasping the change in luminance at the place where the illumination direction is switched. In the step portion, the brightness is significantly different when the illumination light is emitted from the right direction and when the illumination light is emitted from the left direction. When the same place is illuminated from both the left and right directions, shadows do not occur and it is difficult to distinguish it from the flat part.

When the illumination direction is switched for each small irradiation area as in this embodiment, the illumination light in both directions is inevitably mixed in the vicinity of the small irradiation area boundary. For this reason, it is difficult to clearly recognize the step portion in the region in which the illumination lights in both directions are mixed as described above.

When the edge of the label edge overlaps (accidentally) in this area, it is difficult to recognize where the edge of the label edge is. In this way, it is difficult to recognize whether or not there is a step in the region where the illumination light in the left-right direction is mixed.

When the value of p / wd is about 4, the position of the label edge or the like can be specified with an accuracy of about p. When this condition is satisfied, the intensity difference of the illumination light from the left and right becomes sufficiently large at least near the center of the small irradiation area.

Outside the vicinity of the central portion, the illumination light from the left and right is mixed and the step cannot be recognized sufficiently. For this reason, the label edge can be detected using only the data in the vicinity of the central portion, but the accuracy of p appears because only the data in the vicinity of the central portion can be used.

When p / wd is further large and p / wd> 8, a region having a modulation degree of almost 100% extends to the vicinity of the boundary of the small irradiation region. Therefore, the area in which the degree of modulation is low and the level difference is difficult to detect becomes narrow. In reality, the edge of the stepped portion may hang on this low-modulation region, but if the width of this region becomes narrower, the accuracy when it hangs on this region also improves, and The probability of hanging is also low. As long as the end of the step portion is in the region where the degree of modulation is almost 100%, the positional accuracy is not limited by the width p of the small irradiation region.

Although the position resolution is practically close to that of the line sensor, it can be said that the position resolution is practically unlimited. In this way, if p / wd is sufficiently large, dramatically higher accuracy and resolution can be obtained.

Since the broken line pattern appears clearly, the detection accuracy of the broken line pattern is also improved. However, depending on the image processing method, if p becomes too large,
It becomes difficult to judge whether or not there is a step.

FIG. 29 shows the ratio of the sections having a modulation factor of 99% or more in the section from x = 0 to x = p. Referring to the figure, the ratio of the high resolution region exceeds 50% when p / wd> 8.

For example, when p / wd = 10, 62.8.
The area of% is the high resolution area. At this time, the end point of the label edge (the points corresponding to the four corners of the label) is 62.8%.
It is included in the high resolution region with a probability of, and included in the low resolution region with a probability of 37.2%. When included in the high resolution area, the end point position of the label edge is specified by the resolution (for example, 0.1 mm) of the line sensor.

When it is included in the low resolution area, the end point position of the label edge has a resolution about the width of the low resolution area (for example, when p = 5 mm, 5 mm × 37.2% = 1.
86 mm).

Based on the above calculation, the illuminance distribution in the linear reading area 220 when p, d, and w take respective values was calculated. FIG. 22 is a diagram showing the state of the illuminance distribution when p / wd = 1.

In this case, the pitch of the slits is too narrow, the distance between the slits and the reading area is too wide, or the directivity of the illumination lights 410 and 415 is insufficient, so that the comb-shaped pattern is completely blurred. Light from both left and right directions is mixed in the entire reading area.

In this state, the step detection cannot be performed in the almost same state as illuminating with a light source of half the light intensity from the left and right without the comb-shaped slit. Figure 23 shows p / w
The figure showing the mode of illuminance distribution when d = 2 is shown.

In this case, the "modulation degree" is about 55%. At any position in the reading area 220, the illumination light is applied from both the left and right directions, so that the contrast of the dark line or the bright line in the step portion is low.

Therefore, although the step can be detected,
The “modulation degree” is considerably reduced compared to the maximum value. P in FIG.
The figure showing the mode of illuminance distribution when / wd = 4 is shown. In this case, the “modulation degree” is almost 100%, and the light from the left and right directions is sufficiently separated near the center point of each small irradiation area.

At this time, it is possible to detect the position of the step region (address label) with a resolution of p in the main scanning direction. FIG. 25 shows a diagram showing the state of the illuminance distribution when p / wd = 8. In this state, it is possible to sufficiently distinguish the boundary portion of the small irradiation area.

Next, the effect of the step detecting device according to the present embodiment will be explained. In this embodiment, special illumination is performed by using a comb-shaped slit, and thereby a step is detected with high accuracy and high accuracy.

The image obtained by the method of the present invention is very similar to the one obtained by the conventional uniform illumination without the comb structure, which reflects the density distribution of the writing surface, but at the edge portion of the label. The signal is modulated with a signal having a specific cycle and a specific phase.

Therefore, it is possible not only to extract the information for step detection from the obtained image, but also to use the obtained image for recognition of the characters printed on the label. Is.

The illuminating device according to the present invention can be easily realized by installing a comb-shaped light-shielding plate according to the conditions shown in the claims without using a light source having a high degree of parallelism. Comb-shaped slits can be manufactured at very low cost and are highly effective in detecting steps.

If the step detecting device according to the present embodiment is incorporated in a mail address reading / sorting machine, etc., the address recognition section can quickly and accurately detect the area of the address label or the address window where the address is described. It is possible to exert synergistic effects such as improving the recognition rate of addresses and the processing speed.

In most cases, a letter image acquisition device is originally incorporated in the mail address reading / sorting machine. Therefore, it is possible to add the function of detecting a step in addition to the original function at the cost of simply installing the comb-shaped light shielding plate near the reading area.

Although the ninth embodiment of the present invention has been described in detail above, the present invention is not limited to the configuration of this embodiment.

For example, with respect to the resolution of the CCD line sensor, at least about 100 μm is required to detect the step portion in the sub scanning direction. However, the level difference can be detected even if the resolution in the main scanning direction is not so high.

However, the resolution in the main scanning direction is 100 μm.
Depending on the degree, there is a possibility that the acquired image can be shared with the character recognition. The level difference can be detected by selecting one point or several points for each small irradiation area and reducing the information amount in the main scanning direction.

Line illumination and line reading area 200
When a comb-shaped light-shielding plate is placed between them, the illuminance pattern in the line-shaped reading area is determined by the shape of a part of the comb-shaped light-shielding plate.

That is, in FIG. 26, the light beam emitted from the line illumination to reach the line-shaped reading region is in the two planes extending in the 45 ° oblique direction to the left and right of the line-shaped reading region (illumination light 410 or 415 in FIG. 26). Is almost included in the plane including).

Therefore, what is important for the shape of the light shielding plate is the shape of the portion where the light shielding plate intersects these two planes. If the light-shielding portions and the light-transmitting portions are arranged in the same manner on the straight line portions 440 and 445 shown in FIG. 26,
The illuminance pattern of the linear reading area is the same regardless of the shape of the other portions.

Therefore, the same effect can be obtained regardless of whether the shading plate shown in FIG. 15 or the shading plate shown in FIG. 28 is used. Further, since the light shielding plate should not prevent the image pickup unit from reading the reading area, a gap 450 is required near the reading area.

However, the image information of the entire reading area is not necessary for detecting the step, and the step can be detected if there is information of one point or several points in the small irradiation area. Therefore, the shape of the slit may be such that a light shielding portion is attached only to a necessary portion and they are connected by a thin wire as shown in FIG.

When the wire portion is near the boundary of the small irradiation area, the boundary of the small irradiation area often has a blurred illuminance pattern and cannot be used for step detection.

The shape of the comb-shaped light-shielding plate is not limited to the one in which the width of the light-shielding portion is equal to that of the transmitting portion. For any one of the light-shielding portions, if the width p satisfies p / wd> 8, the shadow of that portion appears in the reading area with a sufficient width and a modulation factor of 100%. Further, if any one of the transmissive portions has a width p satisfying p / wd> 8,
The shape of that portion appears in the reading area with a sufficient width and a modulation of 100%. Therefore, the read image of that portion can be used for step detection, and such an image is also included in the present invention.

The incident angles of the left and right illumination lights do not necessarily have to be equal.

Although various modifications can be made as described above, these modifications are all included in the present invention without departing from the spirit of the present invention.

(Tenth Embodiment) FIG. 30 shows the overall structure of a step detecting device according to a tenth embodiment of the present invention. In addition, FIG. 31 is a front view of the step detecting device of FIG. 30 when viewed from the front side. Further, FIG. 32 is a top view of the step detecting device of FIG. 30 when viewed from above.

The step detecting device of the present embodiment is used for, for example, an address label of a mail item, a position of an address display cellophane window (address window), an area detecting device, and the like. It consists of three parts.

The illumination unit is the most important part that characterizes this embodiment. The illumination unit irradiates a letter such as a postal matter with illumination light from both left and right directions at a large incident angle, and two illumination devices 310 and 315 that emit an illumination beam from the elongated exit to the linear region 220. and,
It is composed of a transparent glass substrate 437 installed near the surface of the letter 200.

On this transparent glass substrate, two comb-shaped light-shielding patterns are formed in order to select the illuminating light that enters at each irradiated point. Due to the action of the light-shielding pattern, the illumination light 410 emitted from the illumination device 310 is obliquely upward from the left side, and the illumination light 415 emitted from the illumination device 315 is obliquely upward from the right direction. Alternate positions within the linear reading area 220 on the surface of the letter 200 conveyed to are simultaneously illuminated. The details of the illumination unit will be described in detail below.

The left and right illumination devices 310 and 3 which emit an illumination beam from the elongated emission port toward the linear region 220.
A line type light guide is used for 15. A line-type light guide is one in which a light beam emitted from a light source such as a halogen lamp is once collected and made incident on an optical fiber bundle that is a bundle of optical fibers, and the output end of the optical fiber bundle is linear (for example, two lines on one straight line). The optical element is suitable for uniformly illuminating a line-shaped region.

Incident angles of the illumination light 410 and the illumination light 415 emitted from this to reach the reading area 220, that is, the letter 2
The angle θ formed by the normal line of the 00 plane is equal to each other, and each θ is about 45 °.

The illumination capabilities of the two illumination devices 310 and 315 are equal to each other, and when the system is viewed from directly above, the illumination devices 310 and 315 are in symmetrical positions with respect to the reading area 220.

The reading area 220 is a line-shaped area having a longitudinal direction perpendicular to the sub-scanning direction 230, that is, parallel to the main-scanning direction, and the image of this line-shaped area constitutes a CCD line image sensor which constitutes an image pickup section. Read by 540.

The light-shielding patterns formed on the transparent member have a shape as shown in FIG. 32, and are arranged so that they are staggered left and right. This is the light shield 417 in FIG.
Becomes

The illumination lights 410 and 415 emitted from the illumination devices 310 and 315 and reaching the reading region 220 are irradiated to the reading region 220 by the presence of the light shielding part 437 as shown in FIG. And illuminates the reading area. Illumination light 4
The 10 illumination beams illuminate a number of illumination spots 221 and the illumination beam from illumination light 415 illuminates a number of illumination spots 222.

Further, when the surface of the letter 200 is flat, both the illumination light 410 and the illumination light 415 illuminate the linear reading area 220 with a uniform illuminance.

As shown in FIG. 19, a large number of irradiation spots 221 illuminated by the illumination light 410 and a large number of irradiation spots 222 illuminated by the illumination light 415 are alternately arranged on the linear reading area 220. Alternately (22
1, 222, 221, 222, ...).

The letter 200 is a linear reading area 220.
Since the sheet is conveyed in the conveying direction 230 that is orthogonal to the longitudinal direction, the reading area 220 scans the entire surface of the letter 200 from right to left.

Therefore, a large number of irradiation spots 221,
222 is also scanned from right to left over the entire surface of the letter 200, so that the entire surface of the letter 200 is scanned along the loci of the irradiation spots 221 and 222 in the transport direction 23.
It is divided into a number of elongated small irradiation area trajectories parallel to zero.
This state is shown in FIG.

That is, the picked-up image of the surface of the letter 200 shows a large number of small irradiation area loci 3 by the illumination light 310 from the left direction.
Is composed of a large number of small radiation area path 322 by the illumination light 315 from 21 and to the right, and they small radiation area trajectories
The traces 321 and the small irradiation region loci 322 are arranged alternately every other line.

Further, as shown in FIG. 30, the imaging lens 530 is located above the linear reading area 220, and the image is formed on the CCD line image sensor 540 located above the imaging lens 530. Image and image.

When the letter 200 is conveyed in the sub-scanning direction 230, the CCD line image sensor 540 captures and outputs an image of the entire letter 200. The image data thus obtained is sent to the image processing unit 100, where the step position information is extracted.

As described above, the present apparatus is exactly the same in configuration and principle as the apparatus described in the eighth embodiment, but instead of inserting the comb-shaped light-shielding plate from the left and right of the reading area, a glass plate is used. It is characteristic in that the pattern of the comb-shaped shading plate is baked so that only that portion is blocked from light.

The image obtained by using the illumination unit and the image pickup unit as described above is the same as the image obtained by the configuration of the above embodiment, and the image as shown in FIG. 20 is obtained.
It is possible to use the same image processing method for detecting the step portion.

Next, the effect of the step detecting device according to the present embodiment will be explained. When the light-shielding pattern is designed in the same manner as in Example 8, the value of d in a typical case needs to be several mm or less.

It is assumed that the mail letters actually conveyed by the mail address reading / sorting machine are in various states, and the conveying speed is usually as high as several meters per second. If the interval between the notched portion of the comb-shaped slit and the transport path of these letters is close to each other in this way, the letter may be caught in the slit and damaged.

In order to solve such a problem, in the present embodiment, the pattern of comb-shaped slits is printed on the glass plate.

When a slit pattern is printed on a glass plate, since there is no jagged portion in terms of physical shape, the possibility of letter damage is extremely low. Further, the slit itself will not be bent, and the durability can be improved.

Furthermore, by separating the letter and the optical reading section with a glass plate, it is possible to prevent dust and the like from adhering to the optical reading section, and to facilitate maintenance. In addition, compared with the case where two slits are inserted from the left and right to adjust the spacing, when the pattern of the two slits whose positional relationship is determined from the beginning is printed on the glass plate, the adjustment work can be omitted and the assembly can be omitted. It leads to cost reduction.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the configuration of this embodiment. For example, an opaque layer may be formed on the front side or the back side of the glass plate. This opaque layer may be a slit pattern drawn with an opaque ink, or an opaque pattern may be vapor-deposited. A comb-shaped opaque slit and a comb-shaped glass plate may be combined to form a flat plate as a whole.

The transparent member may be sapphire glass.

The light-shielding portion may be a light-absorbing opaque member, may be a mirror surface that reflects light in a direction other than the irradiated area, or may be light in a direction other than the irradiated area. It may be a diffuser plate that scatters.

A diffractive plate that diffracts light in a direction other than the irradiated area may be used. It may be a lens or a prism that refracts light in a direction other than the irradiated area. As described above, the light-shielding portion is not limited to one in which the light-absorbing material for light-shielding is formed on the transparent member, but includes one having a three-dimensional structure such as a lens formed for light-shielding.

Even if a pattern other than a black and white comb-shaped pattern is formed, the illumination light from the light source is applied to a desired irradiation spot so that a desired illuminance distribution can be obtained in the reading area, and other irradiation spots are irradiated. What uses a light-shielding portion in which a pattern is formed so as not to be irradiated is included in the present invention.

In addition, the light-shielding portion prevents the illumination light traveling toward the irradiation spot other than the desired one from going straight, and transmits the light beam of the illumination light reaching the desired irradiation spot in order to make the illumination light reaching the desired irradiation spot go straight. The part is not limited to being transparent.

By forming a pattern such as a mirror surface / diffuser / diffraction plate on a portion other than the light-shielding portion and reflecting / diffracting / refracting the illumination from the light source, it is possible to make the light reach a desired irradiation spot. It may be one.

Such a thing also corresponds to a "light-shielding part in which a pattern for obtaining a light-shielding effect is formed" in the claims, and the effect of this embodiment can be obtained by such a thing.

An example of this is shown in FIG. FIG. 37 shows FIG.
3 is a cross-sectional view of the system taken along a plane including the left side illumination light 410 at 0 and the reading unit 20. FIG.

The illumination light 410 emitted from the left-side light source is refracted in its optical path by the light-shielding portion in which a pattern for obtaining a light-shielding effect is formed on the transparent member, and all the light is left-side illumination light 41.
0 towards the irradiation spot 221 to be irradiated,
The irradiation spot 222 to be irradiated with the illumination light 415 on the right side is not irradiated.

As described above, the pattern for obtaining the light blocking effect is not limited to the pattern for not irradiating the irradiation light 410 to the irradiation spot 222, but includes the pattern for applying the irradiation light 410 to the irradiation spot 221.

A light-shielding portion having a pattern is formed so that the illumination light from the light source irradiates a desired irradiation spot and does not irradiate other irradiation spots so that a desired illuminance distribution can be obtained in the reading area. What has been included in the present invention.

Line illumination and line reading area 200
When a comb-shaped light-shielding plate is placed between them, the illuminance pattern in the line-shaped reading area is determined by the shape of a part of the comb-shaped light-shielding plate.

That is, in FIG. 26, the light beam emitted from the line illumination to reach the line-shaped reading region is in the two planes extending in the 45 ° oblique direction to the left and right of the line-shaped reading region (illumination light 410 or 415 in FIG. 26). Is almost included in the plane including). Therefore, what is important for the shape of the shading plate is the shape of the portion where the shading plate intersects these two planes.

This straight line portion 440 and 4 shown in FIG.
If the arrangement of the light-shielding portion and the transmitting portion on 45 is the same, the illuminance pattern of the linear reading area is the same regardless of the shape of the other portions. Therefore, FIG.
The effect is the same even when the patterns shown in FIG. 3, FIG. 34, FIG. 35, FIG. 36, etc. are formed.

The shape of the comb-shaped light-shielding plate is not limited to the one in which the width of the light-shielding portion is equal to that of the transmitting portion. For any one of the light-shielding portions, if the width p satisfies p / wd> 8, the shadow of that portion appears in the reading area with a sufficient width and a modulation factor of 100%. Further, if any one of the transmissive portions has a width p satisfying p / wd> 8,
The shape of that portion appears in the reading area with a sufficient width and a modulation of 100%. Therefore, the read image of that portion can be used for step detection, and such an image is also included in the present invention.

The incident angles of the left and right illumination lights do not necessarily have to be equal.

Although various modifications can be made as described above, these modifications are all included in the present invention without departing from the spirit of the present invention.

Also, the number of illumination means is not always two.

The illumination light may be incident on the light irradiation area from two directions by changing a part of the optical path of the illumination light emitted from one light source. FIG. 41 is a conceptual diagram showing the example. The illumination light 414 emitted from the illumination unit 312 is blocked by the light shielding unit 434, and the illumination light reaches only the irradiation spot to be illuminated from the left side.

The illumination light 4 emitted from the illumination unit 312
A part of the light beam 12 is reflected by the light shielding unit 432, the optical path is changed, and the illumination light reaches only the irradiation spot to be illuminated from the right side.

The light shielding portion 434 has the above-described shape (for example,
Comb-shaped slits) can be used. Further, the light shielding portion 432 is a mirror surface that reflects light only in a necessary portion, and the other portions are antireflection surfaces that absorb light.

[0344]

As described above, according to the present invention,
The step on the letter surface can be accurately detected without being affected by the color density distribution such as the print content on the letter surface.
Therefore, it is possible to accurately detect the position of the address label and the like even for direct mails with large color advertisements, which has been increasing in recent years. Due to the effect of this accurate detection, the false recognition of the address due to the false recognition of the non-address portion as the address is significantly reduced.

Further, by detecting the address label position, the area to be processed for the address recognition is reduced, and the processing time required for the recognition process is shortened and the processing circuit is downsized. Is obtained. In this way, it is possible to greatly contribute to the efficiency of postal processing.

[Brief description of drawings]

FIG. 1 is a perspective view showing an entire step detecting device according to a first embodiment of the present invention.

FIG. 2 is a front view of the step detecting device of FIG. 1 seen from the front side.

FIG. 3 is a diagram showing an example of an arrangement of small irradiation areas used in the step detecting device according to the first embodiment.

FIG. 4 is a view for explaining an example of how to make comb-shaped illumination used in the step detecting device of the first embodiment.

FIG. 5 is a diagram showing an example of an image output from the imaging unit of the step detecting device according to the first embodiment.

FIG. 6 is a front view showing an arrangement position of slits in the step detecting device according to the first embodiment.

FIG. 7 is a plan view of an arrangement position of slits in the step detecting device of the first embodiment when viewed from above.

FIG. 8 is a diagram showing an example of a configuration of a small irradiation area used in the step detecting device according to the second embodiment of the present invention.

FIG. 9 is a diagram showing an example of a configuration of a small irradiation area used in a step detecting device according to a third embodiment of the present invention.

FIG. 10 is a front view showing a step detecting device according to a sixth embodiment of the present invention.

FIG. 11 is a diagram showing an example of an image output from the imaging unit of the step detection device of the sixth embodiment.

FIG. 12 is a block diagram showing an entire step detection processing device according to a seventh embodiment of the present invention.

FIG. 13 is a diagram showing an entire step detecting device according to eighth and ninth embodiments of the present invention.

FIG. 14 is a front view of the step detecting device shown in FIG.

15 is a top view of the step detecting device shown in FIG.

FIG. 16 is a diagram for explaining the spread of light emitted from an optical fiber.

FIG. 17 is a diagram for explaining the spread of light emitted from an optical fiber.

FIG. 18 is a diagram illustrating an illumination method.

FIG. 19 is a diagram illustrating an illumination method.

FIG. 20 is a diagram of an image output from the imaging unit.

FIG. 21 is a diagram showing a relationship between p / wd and “modulation degree”.

FIG. 22 is a diagram showing an illuminance distribution with p / wd = 1.

FIG. 23 is a diagram showing an illuminance distribution with p / wd = 2.

FIG. 24 is a diagram showing an illuminance distribution with p / wd = 4.

FIG. 25 is a diagram showing an illuminance distribution with p / wd = 8.

FIG. 26 is a view for explaining a light blocking plate (slit).

FIG. 27 is a diagram showing a first modification of the slit.

FIG. 28 is a diagram showing a second modification of the slit.

FIG. 29 is a diagram showing a ratio of a region having a modulation degree of 99% or more.

FIG. 30 is a diagram showing an entire step detecting device according to a tenth embodiment of the present invention.

31 is a front view of the step detecting device shown in FIG. 30. FIG.

32 is a top view of the step detecting device shown in FIG. 30. FIG.

FIG. 33 shows an example of forming a light shielding part on a transparent substrate.

FIG. 34 is an example of forming a light shielding portion on a transparent substrate.

FIG. 35 is an example of forming a light-shielding portion on a transparent substrate.

FIG. 36 is an example of forming a light-shielding portion on a transparent substrate.

FIG. 37 is an example of forming a light shielding portion on a transparent substrate.

FIG. 38 is a diagram for explaining the principle of conventional level difference detection by oblique illumination.

FIG. 39 is a view for explaining the principle of conventional stamp perforation detection.

FIG. 40 is a diagram for explaining a conventional triangulation method.

FIG. 41 is a diagram showing a step detecting device in the case where there is one illuminating section.

[Explanation of symbols]

100 ... Image processing unit, 200 ... Letter, 210 ... Address label, 211 ... Stamp, 220 ... Read area, 221 ... Spot, 222 ... Spot, 223 ... Label edge shadow, 224 ... Label edge bright line, 230 ... Letter Transport direction or sub-scanning direction, 310 ... Illumination device (left), 315 ... Illumination device (right), 321 ... Small irradiation region locus by illumination light (left), 322 ... Small irradiation region locus by illumination light (right), 410 … Illumination light (left), 415…
Illumination light (right), 420 ... Reflected light on the writing surface, 430 ... Slit (left), 435 ... Slit (right), 437 ... Shading portion, 440 ... Crossing portion of the shading plate and illumination light (left), 4
45 ... the intersection of the light shield and the illumination light (right), 450 ...
The gap of the light shielding plate for the imaging unit to look into the reading area, 53
0 ... Imaging lens, 540 ... CCD line image sensor.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Motomiya 1 Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center Co., Ltd. (56) Reference JP-A-8-147405 (JP, A) Kaihei 9-61113 (JP, A) JP 60-181879 (JP, A) JP 53-62599 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11 / 00-11/30 B07C 1/00-9/00

Claims (12)

(57) [Claims] 1. Illumination means for illuminating an object with illumination light,
In a step detecting device, which comprises an image pickup means for inputting an image of a region illuminated by the illumination light by the illumination means, and which optically detects a step on the object to be inspected by using the illumination means and the image pickup means, A step detecting device, characterized in that the surface of the object to be inspected is divided into a plurality of small irradiation regions each of which is a two-dimensional region, and irradiation light is irradiated to adjacent small irradiation regions from mutually different directions. 2. An illuminating means for irradiating a test object conveyed in a predetermined conveying direction with a linear illuminating light intersecting with the conveying direction, and a linear illuminating light is radiated by the illuminating means. A step detecting device for optically detecting a step in a direction parallel to the transport direction on the object using the illuminating means and the image capturing means. The means divides the image on the surface of the object into a plurality of small irradiation area loci parallel to the conveyance direction of the object, and the small irradiation area paths are adjacent to each other in the direction of irradiation light. Irradiation area
The light irradiation area to which the linear illumination light is irradiated is divided into a plurality of irradiation spots so that the trajectories are in mutually different directions, and adjacent irradiation spots are simultaneously irradiated with the illumination light from different directions. A characteristic step detecting device. 3. The irradiation direction of the illumination light is switched alternately for each of adjacent irradiation spots.
The first and second illuminating devices are arranged to face each other on a line parallel to the conveyance direction of the object to be inspected, and illuminate illumination light from the first and second directions, respectively. The step detecting device according to claim 2, further comprising: 4. Illuminating means for irradiating a test object conveyed in a predetermined conveying direction with linear illumination light intersecting with the conveying direction, and linear illumination light is emitted by the illuminating means. A step detecting device for optically detecting a step in a direction parallel to the transport direction on the object using the illuminating means and the image capturing means. The means divides an image on the surface of the object to be inspected into a plurality of small irradiation areas along a direction intersecting the conveyance direction of the object to be inspected, and It is characterized in that the irradiation direction of the linear illumination light is switched for each of the small irradiation regions according to the transport operation of the test object so that the directions are different from each other between adjacent small irradiation regions. Step detection device. 5. The irradiation direction of the illumination light is a first direction and a second direction that are switched for each adjacent small irradiation area, and the illumination unit is a direction that intersects with a conveyance direction of the test object. First and second illumination devices that are arranged on the line so as to face each other and emit illumination light from the first and second directions, respectively, and means for alternately outputting the illumination light from the first and second illumination devices. The step detecting device according to claim 4, further comprising: 6. Illumination means for irradiating an object with illumination light,
In a step detecting device, which comprises an image pickup means for inputting an image of a region illuminated by the illumination light by the illumination means, and which optically detects a step on the object to be inspected by using the illumination means and the image pickup means, The image pickup means is composed of an area sensor capable of picking up a two-dimensional light irradiation area at a time, and the illumination means is provided with two two-dimensional light irradiation areas.
A step detecting device, characterized in that it is divided into a plurality of small irradiation regions composed of three-dimensional regions, and irradiation light is irradiated to adjacent small irradiation regions from mutually different directions. Used 7. illumination means for irradiating illumination light to the test object, an imaging means for inputting an image of an area which the illumination light is irradiated by the illuminating means, an optical system a step on the test object And a means for executing processing on the object based on the step information detected by the step detecting means, wherein the step detecting means is the step of detecting the surface of the object to be inspected. A processing apparatus, characterized in that the upper part is divided into a plurality of small irradiation areas each consisting of a two-dimensional area, and irradiation light is irradiated to adjacent small irradiation areas from different directions. 8. One of an illumination means for irradiating an object conveyed in a predetermined conveyance direction with a linear illumination light intersecting the conveyance direction, and an illumination light emitted by the illumination means. The illumination means and the light-shielding means for inputting the image of the light irradiation area to which the linear illumination light obtained through the illumination means and the light-shielding means is input are provided. In the step detecting device that optically detects a step in a direction parallel to the transport direction on the object using the image pickup unit and the image pickup unit, the light shielding unit is a part of illumination light emitted from the illumination unit. The step detection device is characterized in that the light irradiation region is divided into a plurality of irradiation spots by changing the optical path of the above, and illumination lights from different directions are incident on adjacent irradiation spots. 9. Illumination means for irradiating illumination light from two or more directions toward a line-shaped region on a test object conveyed in a predetermined conveyance direction, the line-shaped region being orthogonal to the conveyance direction. Light-blocking means inserted between the lighting means and the line-shaped area so that only specific illumination light from a specific direction reaches a specific portion on the area and the illumination light from other directions is blocked; And an image pickup unit for inputting an image of a circular region, and a detection unit for optically detecting a step in a direction parallel to the carrying direction on the object based on the image picked up by the image pickup unit. In the step detecting device that optically detects a step on the object using the illuminating means, the light shielding means, the image capturing means, and the detecting means, in the optical path direction of the illumination light passing through the light shielding means. The measured light-shielding means and the light The distance between the illuminating means and the illuminance of the illumination light emitted from one point of the illuminating means on the plane separated by a unit distance from the illuminating means is √e of the illuminance at the central point. A step detecting device having a relationship of p / wd> 4, where w is a radius of illumination light and p is a width of either a light-shielding portion or a light-transmitting portion of the light-shielding means. 10. Illumination means for irradiating illumination light from two or more directions toward a line-shaped region orthogonal to the conveyance direction on the object conveyed in a predetermined conveyance direction; Light-blocking means inserted between the lighting means and the line-shaped area so that only specific illumination light from a specific direction reaches a specific portion on the area and the illumination light from other directions is blocked; And an image pickup unit for inputting an image of a circular region, and a detection unit for optically detecting a step in a direction parallel to the carrying direction on the object based on the image picked up by the image pickup unit. In the step detecting device that optically detects a step on the object using the illuminating means, the light shielding means, the image capturing means, and the detecting means, in the optical path direction of the illumination light passing through the light shielding means. The measured light-shielding means and the measured When the illuminance of the illumination light emitted from one point of the illuminating means is √e of the illuminance at the center point on a plane separated by a unit distance from the illuminating means, A step detecting device having a relationship of p / wd> 8, where w is a radius of the illumination light and p is a width of either the light-shielding portion or the light-transmitting portion of the light-shielding means. 11. The step detecting device according to claim 8, wherein the light shielding unit is a transparent member in which a pattern for obtaining a light shielding effect is formed on a transparent member. . 12. The method according to claim 8, further comprising means for executing a process for the object to be inspected based on a step detected by the detecting means.
The step detection device according to any one of items.