JPH08195861A - Original reader, image forming device and platen cover - Google Patents

Abstract

PURPOSE: To provide an original reader, a platen cover and an image forming device capable of discriminating an original area regardless of the color of an original without using an optical element dedicated to the discrimination of the original area and realizing a variable original area discrimination function and a free range original area discrimination function as well. CONSTITUTION: For this original reader, a reflection part 5 for reflecting irradiating light from an illumination member 3 so as to make the positive reflected light be incident on an image read member 4 is provided on the side of the original abutted surface of an original pressure-contact member 2 and also, the image read member 4 is provided with an original area discrimination means 6 for comparing the light quantity of the reflected light made incident on the image read member 4 with the light quantity of scattered reflected light from a white reference original set beforehand, recognizing the area as a non- original area when the light quantity of the reflected light made incident on the image read member 4 exceeds the light quantity of the scattered reflected light from the white reference original and discriminating the original area A on a platen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a CCD (Charge).
Coupled Device) or PDA (Photo)
an image reading member such as an O. Diode Array), and an original reading device for converting original image information into electrical image data; an image forming apparatus such as a digital copying machine including the original reading device; The present invention relates to a platen cover used in a document reading device, and more particularly, to improvement of a function of identifying a document region by using the image reading member.

[0002]

2. Description of the Related Art Conventionally, this type of document reading apparatus is shown in FIG.
As shown in FIG. 2, a platen 21 on which a document is placed, a document pressure contact member 22 having a document pressure contact surface 22a having a planar shape for bringing the document into close contact with the platen 21, and a document pressure contact member 2
An illumination member 23 for irradiating a document that is in close contact with the platen 21 by means of 2 and a position where the reflected light reflected by the document is incident, and the light amount of the reflected light according to the image information of the document is changed to an electrical image. It is composed of an image reading member 24 which is converted into data. Further, in the case of a glossy document, surface reflection occurs on the surface thereof, and the light amount of the regular reflection light L1 reflects the shape of the illumination member 23 as well as the image information of the document, and the light amount is high. The above-mentioned image reading is performed because the scattered reflection light including the information of the density of the original is erased by the regular reflection light (that is, the illumination means is seen when the platen 21 is viewed from the direction in which the regular reflection light L1 is reflected). Member 24
Is arranged at a position where the scattered reflected light L2 of the reflected light reflected by the original is incident and the regular reflected light L1 is not incident. In the document reading device, the document is placed on the platen 21 and the document pressing member 22 is closed, and the document is illuminated by the illuminating means 23 and the image data is output from the image reading member 24. Is reading. Further, the image forming means performs image processing using the image data of the original document and forms an image based on the image data subjected to the image processing. The image forming apparatus is composed of at least the document reading device and the image forming means.

Prior to the document reading operation, the document reading device is instructed to the image forming means which image data of the image data output from the image reading member corresponds to the document area. Some have a document area identification function for checking the document area on the platen.

For example, in Japanese Unexamined Patent Publication No. 59-68728, one surface of the original pressure contact surface is formed as a mirror surface, and illumination light is specularly reflected in a non-original area, that is, an area where there is no original between the original pressure contact surface and the platen. The image data output from the image reading member corresponds to black, and the entire platen is illuminated prior to the document reading operation. Image data is output from the image reading member by irradiating with the means, and the area where the image data does not correspond to black is identified as the original area, that is, the area where the original is present between the original pressing surface and the original table. . The original area can be identified by the same identification method by forming the entire original pressure contact surface to be black and absorbing all the illumination light in the non-original area. However, in this case, when a tracing paper or a thin original is read, there is a problem that the entire image data becomes darker than when the entire original pressure contact surface is a mirror surface. Further, in Japanese Patent Laid-Open No. 63-280569, the entire pressure contact surface of the original is colored with a color such as yellow, and when identifying the original area, the reflected light of the same color as the coloring is blocked before the image reading member. The optical filter is inserted so that the scattered reflection light from the non-original area does not enter the image reading member at all, and the area with a large light amount is identified as the original area.

In these document reading devices, the image reading member is used to fetch the data for identifying the document area. Therefore, the document reading device is used to identify the standard document such as A4, B4, A3. It is not necessary to provide a separate photo sensor, and the entire platen can be divided into a matrix to determine the presence or absence of a document for each cell, regardless of whether the document is fixed or irregular. , The original area can be identified regardless of the position of the original on the original table (hereinafter, the former is referred to as an irregular original area identification function, and the latter is referred to as a free registration original area identification function). ).

However, in the above-mentioned document reading apparatus, a solid pattern of a single color such as a mirror surface, a black surface, and a yellow color is formed on one surface of the document pressure contact surface, and the light amount of the reflected light reflected by the document pressure contact surface and the light reflected by the document. Since the original area is identified based on the difference between the reflected light quantity and the original area, in the case of an original that is framed in the same color as the solid pattern formed on the original pressure contact surface, the original area Since the image data of 1 and the image data of the non-original area are the same data, the original area cannot be correctly identified. Since the image forming apparatus extracts the image data of the original from the image data of the entire platen using the incorrect original area information, it cannot form an appropriate image. Image information cannot be formed on the recording sheet.

Further, in the above document reading apparatus, when performing document reading scanning of a transparent document such as an OHP sheet or a semitransparent document such as tracing paper, only the image data in the non-image area has the solid pattern color. Not only the data but also the image data of the original area is covered with the color of the solid pattern. Since the image forming apparatus performs image processing using the image data covered with the solid pattern color, it cannot form an appropriate image. For example, in a copying machine, the image formed on the recording sheet is printed on the back side of the image. Images and solid images will appear.

In order to solve such a problem, in Japanese Patent Laid-Open No. 60-100138, an original pressure contact surface of an original pressure contact member is set to an EL (Electro-Luminescence).
e) It is formed on a light emitting surface made of a plate, and the light emitting surface is turned on to output image data from the image reading member prior to the original reading operation, and the area where the image data corresponds to black is identified as the original area. A document reading device has been proposed. However, in this document reading apparatus, the EL plate is required only for identifying the document area, and since the EL plate is incorporated, the structure of the document pressing member is complicated, which leads to a significant cost increase. It is difficult to secure the amount of emitted light required to identify the original area.

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to read an original area regardless of the color of the original and to identify the original area without using an optical element dedicated to identifying the original area. An object is to provide a device and a platen cover used for the draft reading device.

Another object of the present invention is to provide an original reading device which can realize an irregular original area identification function and a free registration original area identification function, and a platen cover used for the original reading apparatus. To do.

Further, a third object of the present invention is that the image data of the original can be appropriately extracted from the image data of the entire platen, and the image data is not affected by the color of the original pressure contact surface. An object of the present invention is to provide an image forming apparatus capable of forming various images.

[0012]

SUMMARY OF THE INVENTION That is, according to the present invention, a document pressing member for bringing a document placed on a platen into close contact with the platen, and an illumination for irradiating the document brought into close contact with the platen by the document pressing member. A member and an image reading member which is arranged at a position where scattered reflected light of reflected light reflected by the document is incident and specular reflected light is not incident, and which reads image information of the document that the scattered reflected light has. In the document reading device provided, a reflection portion is provided on the document contact surface side of the document pressure contact member so as to reflect the irradiation light from the illumination member so that the specular reflection light is incident on the image reading member, and For the image reading member, the light amount of the reflected light incident on the image reading member is compared using a preset reference light amount value, and the light amount of the reflected light incident on the image reading member exceeds the reference light amount value. In that case It recognizes the non-document area is original reading apparatus having a document area identification means for discriminating the original area on the platen.

Another aspect of the present invention is the above document reading device,
An image processing unit that performs image processing using the image information read by the image reading member of the document reading unit and the document area information determined by the document area identifying unit, and the image data processed by the image processing unit. The image forming apparatus further includes an image forming unit that forms an image.

Further, a third invention is a platen cover in which a large number of dimples having a diameter of 0.5 to 10 mm are discretely provided on the entire surface of the original contact surface.

Note that, in general, CC in a document reading device
An optical sensor such as D outputs an electric signal such as voltage or current corresponding to the amount of light incident on the optical sensor in a predetermined measurement time, and thus this output signal can be treated as the amount of light. At this time, the output signal itself may be compared, or the calculated value of the output signal may be used for comparison. In a digital image reading apparatus, these electric signals are usually converted into digital signals of about 8 bits to 24 bits using an A / D converter, and the digital signals are subjected to shading correction as necessary. After performing calculations for the above, these are used as data corresponding to the light amount.
Therefore, in the present invention, when a common reference light amount having a constant value is used by a plurality of photosensors, it is simpler to add the configuration because comparison is performed using the data after the above calculation. In the above calculation, in addition to the shading correction, it is also possible to correct factors such as fluctuations in the light emission time of the lamp and changes in the light emission temperature, which vary in the detection value of the optical sensor.

The platen may be made of, for example, glass as long as a document is placed on the platen and the document can be illuminated from below by the illumination means.

The illuminating member may be any one that can illuminate the entire platen. For example, a linear halogen lamp or a fluorescent lamp stretched in the main scanning direction of the platen and a drive for driving it in the sub-scanning direction of the platen. And means.

The image reading member is arranged at a position where scattered reflected light of reflected light reflected from the original enters and normal specular light does not enter, and the image information of the original contained in the scattered reflected light is displayed. Anything can be read, for example CCD or P
An imaging lens may be placed in front of the DA or the like, and the scattered reflected light incident on the imaging lens may be imaged on the CCD or PDA. An optical system that compresses the size of the original area using the imaging lens to form an image is called a reduction optical system. The position where the specularly reflected light is incident is a position in the direction in which the illuminating means can be seen overlapping the original when surface reflection occurs due to the gloss of the original, and since the illuminating member has a width, it has a strip shape. It becomes an area.

The above-mentioned original document pressure contact member is only required to bring the original document placed on the platen into close contact with the platen, and to have a reflection portion for reflecting the specularly reflected light toward the image reading member. , For example, platen cover or A
The reflection portion may be formed on the document pressure contact surface of the DF. As a result, the document pressing member can mix the image data with the information indicating that it is not the document area.

Further, the area for forming the reflecting portion in the original pressure contact surface can be appropriately set according to the type of original to be identified. For example, in the case of a fixed original set at the registration reference position, It is sufficient if the fixed originals are arranged on the platen, and when the fixed originals are pressed by the original pressing member, the fixed originals are provided so that specular reflection light is generated in a unique pattern for each size of the fixed originals. When realizing the standard document identification function, it may be formed so as to traverse the entire original pressure contact surface from the position corresponding to the registration reference position to the opposite side, and when realizing the free registration document identification function. It may be formed on the entire surface of the original pressing surface. In the case of realizing the irregular document identifying function and the free registration document identifying function, the reflecting portions may be formed continuously over the entire area or may be formed in large numbers discretely within the area. Good. When a large number of reflecting portions are discretely formed, one reflecting portion has a diameter of 0.5 mm to 10 mm.
mm, and the spacing between the reflective parts is 0.5 mm
It may be set to -10 mm, and the plurality of reflecting portions may be arranged in a matrix shape based on corners such as triangles and quadrangles, but by randomly arranging, a plurality of reflecting portions located in the vicinity are provided. Are set to different coordinate values in the main scanning direction and the sub-scanning direction, respectively, and the main scanning direction and the sub-scanning direction of the platen can be subdivided more than the distance between the reflecting portions, so that only the original area and the non-original area. The boundary between and can be detected in detail.

It is sufficient that the reflecting portion has a reflecting surface formed at an angle that reflects at least specularly reflected light toward the document reading member. For example, even if the reflecting portion has a dent shape,
It may have a projection shape. And, in the case of the former concave shape, it is effective in that the reflective portion is not worn even for long-term use, and in the case of the latter projection shape, the original pressing member and the original are Since a layer of air is formed between the two, it is preferable that the original is difficult to be sucked when the original pressing member is opened from the platen, and the original placed on the platen can be efficiently exchanged. The reflecting surface may be a flat surface or a curved surface, but if formed into a curved surface,
Even when the original pressure contact surface is slightly inclined with respect to the platen when a thick original is copied, the inclination can be absorbed and a regular amount of specularly reflected light can be reflected in the direction of the original reading member. Furthermore, by making the curvature of the curved surface constant, the amount of specularly reflected light can be made constant regardless of the reflection part of the reflection surface.

When the width of the image reading member 4 is narrower than the width of the platen 1 in the main scanning direction, the image forming lens 8 is arranged in front of the image reading member 4 to form a reduction optical system. Then, as shown in FIG. 5, when the illuminating means is composed of one lamp 3 stretched in the main scanning direction of the platen, the regular reflection light from each of the reflecting portions 5c to 5i arranged in the main scanning direction is generated. The light enters the imaging lens 8 and the image reading member 4 while maintaining the arrangement of the reflecting portions 5c to 5i. However, FIG.
As shown in FIG. 7, when the illumination means is composed of a plurality of light emitting units 3a to 3e arranged in the main scanning direction of the platen, such as a linear halogen lamp, the light emitting units 3a to 3e are shown.
There are reflecting portions 5d and 5h that cannot obtain specularly reflected light in the direction of the imaging lens 8 (image reading member 4) due to the positional relationship between the reflecting portions 5c to 5i arranged in the main scanning direction. Since it is not possible to make the specularly reflected light of the image forming lens 8 (image reading member 4) incident on the image forming lens 8 (image reading member 4) while maintaining the arrangement of the reflecting portions 5c to 5i, as shown in FIG. 4) Reflecting portion 5d that cannot obtain specularly reflected light in the direction,
The reflecting surface of 5h needs to be angled according to the positional relationship with the light emitting portions 3b and 3d. Further, as shown in FIG. 8, the reflecting surfaces of the reflecting portions 5c to 5i may be formed into a curved surface even in the main scanning direction. In this case, even if the original pressure contact surface 2a is slightly inclined with respect to the platen 1, it is possible to absorb the inclination and always reflect a predetermined amount of regular reflection light toward the imaging lens 8 (image reading member 4). Becomes Furthermore, if the reflecting portion is formed into a spherical shape, all of these problems can be solved.

The document area identifying means compares the light quantity of the reflected light incident on the image reading member using a preset reference light quantity value, and the light quantity of the reflected light incident on the image reading member corresponds to this reference light quantity value. If the area is exceeded, the area may be recognized as a non-original area and the original area on the platen may be determined. The reference light amount value is set to distinguish the light amount of the reflected light from the placed document and the light amount of the reflected light from the reflecting portion, and may be set to be between them. , Lambert's cosine law that all incident light is scattered and reflected without being absorbed, and the direction distribution of the intensity of scattered reflected light is proportional to cos θ (θ is the angle that each direction makes with the surface normal) with respect to the surface normal. By setting the perfect reflection surface according to the above, even when reading any document, the document region is not mistakenly recognized as the non-document region by the scattered reflected light from the document. This reference light amount value may be set in advance, or a white reference document attached to the back surface of the platen may be exposed at any time, the scattered reflected light may be read, and the reference value may be directly or calculated based on this value.

When comparing the light quantity of the reflected light and the reference light quantity value, the output image data of the image reading member is changed one by one.
However, it is also possible to compare the light amount in a predetermined area of the reflected light incident on the image reading member with the reference light amount value for each of some image data, and in the latter case, Although the accuracy of discriminating the original area is lowered, the comparison process can be performed at high speed. Further, when identifying an area of an irregular-sized original or identifying an area of a free-registration original, it is not necessary to perform the above-described comparison processing on all original areas, and one or a plurality of detection areas are set and the area is set. The non-original area may be recognized in the inside.

[0025]

In the present invention, since the reflection portion corresponding to the non-original area makes the specularly reflected light incident on the image reading member, the image data of the non-original area includes the information of the light quantity stronger than the reference light quantity value. Some have. Then, the light quantity of the image data is compared with a preset reference light quantity value, and when the light quantity of the reflected light incident on the image reading member exceeds the reference light quantity value, the area is recognized as a non-original area. Thus, the original area on the platen can be identified.

In the present invention, the non-original area is recognized based on the image data of the light quantity larger than the reference light quantity value, and the other area is discriminated as the original area. And the amount of light scattered by the reflecting section never reach the same level.

Further, in the present invention, it is possible to discriminate the original area or the non-original area over the entire platen by forming the reflecting portion on a predetermined area, for example, the entire surface of the original pressure contact surface.

Further, in the present invention, the color of the document pressure contact surface is not limited at all, and since it can be formed in white, the color of the document pressure contact surface does not cover the image data during the document reading operation. Absent.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the document reading apparatus of the present invention is used in a digital color copying machine will be described below with reference to the accompanying drawings. (In the following examples, there are second and third scanning mirrors for keeping the vacant optical path length between the imaging lens and the original document constant, but they are omitted for simplification of description. It can also be used for an image reading device of a type in which the line sensor is directly moved in the sub-scanning direction or a type in which a document is moved to fix the line sensor.

Embodiment 1 FIG. 1 shows a document reading apparatus according to Embodiment 1 of the present invention. This document reading device includes a platen 1 on which a document A is placed,
White document pressure contact surface 2 for adhering the original A onto the platen 1
The original pressing member 2 having a, which is arranged to be openable and closable with respect to the platen 1, the illumination member 3 for illuminating the platen 1 from an oblique 45-degree direction, and the illumination position below the illumination position illuminated by the illumination means 3 ( That is, the mirror 7 is disposed in the vertical direction of the irradiation position of the platen, the image reading member 4 that receives the reflected light reflected by the mirror 7, and is disposed between the image reading member 4 and the mirror 7. The image forming lens 8 forms an image on the image reading member 4 by reducing the image superimposed on the reflected light, and identifies the fixed originals A4, B4, and A3. The digital color copying machine selects a recording sheet based on the identification result of the original area A.

The illumination member 3 is composed of a plurality of linear halogen lamps 3a arranged in a row in the width direction of the platen 1 (hereinafter referred to as the main scanning direction), and the length of the platen 1 is controlled by an illumination means drive motor (not shown). The platen (original) is line-scanned by being driven in a direction (hereinafter, referred to as a sub scanning direction).

Then, in this embodiment, as shown in FIG. 2, two reflecting portions 5 are formed on the document pressure contact surface 2a. The first reflecting portion 5a blocks the irradiation light from the illumination member 3 when the B4 document is placed on the platen 1, and A
4 When the original is placed, it is formed at a position where the irradiation light from the illumination member 3 is not blocked.
The illumination light from the illumination member 3 is blocked when the A3 document is placed on the top, and the illumination light from the illumination member 3 is not blocked when the B4 document is placed thereon. Therefore, when the standard size detection is performed on the document placed on the platen 1, regular reflection light is generated in a unique pattern according to the size. Then, the standard size of the document can be determined by identifying this pattern. The first reflecting portion 5a and the second reflecting portion 5b are formed so as to be separated by 10 mm in the sub-scanning direction.

As shown in FIGS. 3 and 4, these reflecting portions 5 are formed in a hollow shape, and the reflecting surface 5c thereof has a white and glossy flat shape, and is in the sub-scanning direction of the original pressing surface 2a. Is formed at an angle of 22.5 degrees. Therefore, the illuminating means 3 is driven in the sub-scanning direction to move the reflecting portion 5 above.
When it is positioned at an angle of 45 degrees, the specularly reflected light is reflected right below the reflecting surface 5 and is incident on the image reading member 4 via the mirror 7 arranged right below the irradiation position of the platen 1. . Therefore, the amount of scattered light from the document A and the amount of specularly reflected light from the reflector 5 do not have the same light level, and the original region A and the non-original region are distinguished regardless of the color of the original A. You can Further, since the reflection portion 5 is formed on the document pressure contact surface 2a of the document pressure contact member and the specular reflection light is reflected by the document reflection member 4 to the document reading member 4, an optical element dedicated to identifying the document area A is used. You do n’t have to
Further, the structure of the document pressure contact member 2 does not become complicated.

The image reading member 4 divides the analog image data corresponding to the amount of incident reflected light into a plurality of pixels and outputs the CCD image, and a pixel clock generator that outputs a sampling timing signal to the CCD sensor. 4b
This image data is compared with the preset amount of scattered reflected light from the white reference document, and if the amount of reflected light exceeds the amount of scattered reflected light from this white reference document, the area is not A document area identifying means 6 for recognizing the document area and discriminating the document area A on the platen.

The original area identifying means 6 uses the addresses of the two reflecting portions 5 and the light quantity value of the scattered reflected light from the perfect reflecting surface as a reference light quantity value to correspond the identification result of the two reflecting portions 5 with the original size. The discrimination table is held, and the image data at the above address and the reference light amount value are compared with each other in accordance with the driving of the illuminating means 3 in the sub-scanning direction. Is detected, the size of the original is determined based on the determination table, and the size is output to the main body of the copying machine. For example, the first reflecting portion 5a
When the amount of light higher than the reference amount of light is not detected and the amount of light higher than the reference amount of light is detected in the second reflecting portion 5b, the document area identifying means 6 determines that it is the B4 document A. And output it to the copier body.

In the image forming apparatus using this document reading apparatus, since the document area A and the non-document area can be discriminated regardless of the color of the document, the image data of the document is converted from the image data of the entire platen. Since the color of the original pressing surface 2a can be appropriately extracted and the color of the original pressing surface 2a is formed to be white, an appropriate image can be formed without the image data during the original reading operation being covered with the color of the original pressing surface 2a. can do.

Embodiment 2 This embodiment is the same as Embodiment 1 except that the original pressure contact member 2 and the original area identification means 6 are changed to realize the irregular original identification function and the free registration original identification function. .

As shown in FIG. 9, a large number of reflecting portions 5 are discretely and randomly arrayed on the entire surface of the original pressure contact surface 2a of the original pressure contact member 2, and the intervals between the reflective portions 5 are the original area. It was set to 0.5 to 1 mm in consideration of the detection accuracy of. The shape of each reflecting portion 5 is a dimple shape having a constant curvature formed of a part of a spherical surface, and is 0.5 mm to 1 m so that the image reading member 4 can be provided with a sufficient amount of regular reflection light.
It is formed in a size within the m range.

By the way, the above dimples are actually
The condition for allowing the specular reflection light to enter the image reading member 4 at the end of the dimple, that is, the condition for obtaining the specular reflection light in the cross section in the main scanning direction and the specular reflection light for the cross section in the sub scanning direction. In this embodiment, as shown in FIG. 10, the illuminating means 3 in which a plurality of linear halogen lamps 3a to 3c are arranged in the main scanning direction is used and the size is reduced. Since the optical system is used, the reflection direction of the specular reflection light is not always right below the platen. Here, a method for obtaining the depth of the dimple for causing regular reflection will be described.

FIG. 11 shows the relationship of specular reflection when the illumination light is incident on the dimples under the above conditions. A normal vector s at the portion of the reflection surface 5a that causes regular reflection,
When the illumination direction vector a from the lamp to the dimple and the vector b from the dimple to the lower side are expressed using the vector t and the vector normal to the normal vector s, a = −α · s + β · t b = α · s + β・ There is a relationship of t. Then, from the condition that the absolute value of the vector s is 1, the direction cosine vector s of the surface of the dimple
S = (b−a) / | b−a | ... Equation 1 is obtained. From this, the normal vector s of the curved surface of the dimple end required to cause regular reflection can be obtained.

The downward direction component of the normal vector s (z
Component) is given by co from the angle θ formed by the normal vector s and the z axis.
sθ (see FIG. 12), and assuming that the dimple is a part of a spherical surface with a radius r, the dimple depth d is as shown in FIG.
As shown in 2, d = r · (1-cos θ) ... When applying this relational expression to the original when illuminating it in the direction of 45 degrees and reading from below,

[0042]

[Equation 1] Therefore,

[0043]

[Equation 2] And the z component of this is

[0044]

(Equation 3) Becomes From this, if r = 0.5 mm, it is understood from Expression 2 that the dimple depth should be d = 0.5 × (1−0.9239) = 0.038 mm. In the general case, even if the positional relationship with the linear halogen lamp or the positional relationship in the main scanning direction on the platen surface changes, the above relational expression applies,
The dimple depth may be set according to the worst case (dimple depth increases). And
As shown in FIG. 13, each of the reflecting portions 5m, 5n, 5p causes regular reflection at different portions on the reflecting surface according to the positional relationship with the illuminating means 3a, 3b.

As shown in FIG. 14, when reading an original such as paper or tracing paper that diffuses light on the front surface, the illumination light transmitted to the back surface of the original is scattered almost uniformly, and the above-mentioned Since the illumination light is almost evenly scattered by the dimples, the scattered reflected light, and thus the shape of the dimples, is not mixed with the image data, and the show-through does not occur during printing.

As shown in FIG. 15, the original area identifying means 6 has an amplifier 6a with a gain adjusting means for amplifying analog image data from a CCD sensor, and an amplifier according to a sampling timing signal of the pixel clock generator 4b. An A / D converter 6b for converting the output of 6a into digital image data, a shading correction circuit 6c for inputting the digital image data and correcting pixel sensitivity variations of the CCD sensor, and an output of the shading correction circuit 6c And a reference light amount value are compared, and if the output is larger than the reference light amount value, a comparator 6d that outputs a dimple detection signal T and a line signal output from the illumination unit drive motor are counted to determine the sub-value of the analog image data. A line counter 6e for outputting the SS address in the scanning direction,
The pixel area 6f that counts the sampling timing signal and outputs the FS address of the analog image data in the main scanning direction, and the document area A from the FS address and the SS address when the dimple detection signal T is input.
And a discriminating circuit 6g for discriminating the original area.

The shading correction data for each pixel used in the shading correction circuit 6c is read by a reference reflection plate (not shown) having a constant reflectance of 82% provided at one end of the platen 1 and read at that time. A value obtained by multiplying the image data for each pixel by 1.2 is used (that is, the reflectance of 9
Use a value equal to the image data when reading the 8% reference reflector). Then, the shading correction data is stored in the shading correction data storage memory 6h, the shading correction data is sequentially output to the shading correction circuit 6c according to the FS address, and the shading correction circuit 6c uses the shading correction data. Shading correction is performed by dividing the digital image data. Further, the digital image data is divided with a value equal to the image data when a reference reflector having a reflectance of 98% is read as a reference light amount value, and shading is obtained when an original A having a reflectance of 98% or less is read. The output value of the correction circuit 6c becomes 1 or less, while the output value of the shading correction circuit 6c when the reflection unit 5 is read becomes larger than 1. Therefore, in the comparator 6d, for example, only by comparing whether or not the output is larger than 1, even when the glossy document A with a reflectance of about 95% is read, only the dimple detection signal for the reflector 5 is detected. T can be output.

The document area discrimination processing performed by the discriminating circuit 6g includes a sub-scanning direction detection area for discriminating the end portion of the document in the sub-scanning direction and a main scanning direction detection area for discriminating the end portion of the document in the main scanning direction. Is set in advance, the address closest to the original area A in that area is detected, and the original area A is discriminated from those addresses. The processing mode is slightly different.

First, in the irregular document identification mode, FIG.
As shown in FIG. 5, since the registration position R is provided at the left back of the platen (upper left in the figure), the main scanning line having the main scanning direction (FS) direction full width and the sub scanning (SS) direction predetermined width is provided. The scanning direction detection area PFS is set at a position on the left side of the platen 1, and the total width in the sub-scanning direction (SS) and a predetermined width in the main scanning (FS) direction (the value of the FS counter is 100th to 300th lines). A sub-scanning direction detection area PSS having eyes) is set at a position on the back side of the platen 1.

The width of the original area in the main scanning (FS) direction is detected by the main scanning direction end detection circuit 6p shown in FIG. 17 using the main scanning direction detection area PFS. Each time there is the dimple signal, the edge detecting circuit 6p in the main scanning direction is closer to the original area than the address value stored in the address register and whether or not the address is in the detection area in the main scanning direction. , The address of the address register is updated when both conditions are satisfied, and after reading the image data of the entire platen, the address register is moved to the address closest to the end of the original in the area. Is stored, and more specifically, as shown in FIG. 17, it is determined whether the FS address register 6m and the SS address from the line counter 6e are within the area. In some cases, the area comparison unit 6i that outputs an area match signal and the FS address from the pixel counter 6f are stored in the FS address register 6m.
It is judged whether or not the platen is closer to the platen than the register value, and if there is, the address comparison unit 6j that outputs the closest signal, and the judgment that all of the dimple signal T, the area match signal and the closest signal are present. In this case, the main scanning direction detection area PF is composed of a condition determining means 6k for outputting a write signal, and is configured to update the value of the FS address register 6m to the FS address by using the write signal as a trigger.
When the scanning of S is completed, the FS address register 6m has a dimple pfsmin located closest to the end of the document.
The coordinates in the main scanning direction are stored.

The width of the original area in the sub-scanning direction is detected by the sub-scanning direction end detection circuit using the sub-scanning direction detection area. The sub-scanning direction edge detection circuit determines whether or not the FS address from the FS counter is within the area,
In some cases, an area comparing section that outputs an area match signal, a condition determining means that outputs a write signal only once when it is determined that there is a dimple signal and an area match signal, and SS of a line counter triggered by the write signal.
It consists of an SS address register that stores an address,
When scanning of the sub-scanning direction detection area is completed, the sub-scanning direction coordinates of the dimple closest to the document edge are stored in the SS address register.

Finally, the size of the original is specified by setting the value of the SS address register as the width of the original in the sub-scanning direction and the value of the FS address register as the width of the original in the main scanning direction to determine the original area. Output a signal. Thus, A
It is possible to detect the document size of a document other than the standard document such as 3, A4 or the like.

Next, in the free-registration document identification mode, as shown in FIG. 18, four detection areas each having a size extending from the side edge of the platen to the central portion of the platen are set on each side of the platen.

Whenever there is a dimple signal, it is determined in which detection area the address is located, and whether the address is closer to the original area than the address value stored in the address register corresponding to the detection area at that time. If both conditions are satisfied, the address of the address register is updated, and after reading the image data on the entire surface of the platen, the address closest to the end of the document is stored in all the address registers. Is configured. Also,
The four sides of the original area are obtained based on the four addresses of the four detection areas arranged side by side on the platen. Specifically, first, as shown in FIG. 19, assuming that the side of the document is a straight line Lss2 of y = a * x + b,
Detection areas PFS5, PFS6, PFS7, PFS
4 points address pfs5min, pfs6min,
The slope a of the straight line is obtained from pfs7min and pfs8min by the method of least squares, and this straight line is moved in parallel to obtain b from the condition that the straight line is closer to the original area A side than the address of the four points (that is, in FIG. Find the minimum b for which Yi ≦ a * Xi + b holds for the address (Xi, Yi))
Then, the document area end portion Lss2 is obtained. Further, after the straight lines are obtained for the four sides of the original area A, the intersections of these straight lines are obtained, the original area A is specified by using the addresses of the four intersections as the corner addresses, and the original area signal is output. By doing so, even a document not placed at the registration position R can detect the document area A.

In the image forming apparatus using this document reading apparatus, since the original area and the non-original area can be discriminated regardless of the color of the original, the image data of the original is appropriately selected from the image data of the entire platen. Can be extracted, and because the color of the original pressure contact surface is white,
An appropriate image can be formed without the color of the original pressure contact surface being covered by the image data during the original reading operation.

In this embodiment, the shading data is set to a large value in advance to discriminate the white background of the document from the data brighter than that (that is, the data by specular reflection light). By changing the input signal level to the shading correction circuit by adjusting the gain of the amplifier depending on the time of scanning and the time of scanning the original, for example, the gain of the amplifier at the time of detecting the original area is set smaller than that at the time of scanning the original. The same identification can be performed by switching the reading level of the white background so that the original detection unit does not reach the saturation level. Further, in the case of a monochrome copying machine having a small number of gradations of the A / D converter (for example, 6 bits), this method effectively allocates the reading gradations between the black level and the white level and reads with high accuracy. This is an effective method because the white level of the original and the signal of specular reflection light can be discriminated when the original area is detected.

Embodiment 3 In this embodiment, as shown in FIG. 20, a fixed shape is prepared in the same manner as in Embodiment 2 except that the reflection portion 5 is formed in a protrusion shape on the original pressure contact surface of the original pressure contact member 2. The image forming apparatus is adapted to detect an irregular document size. Such a projection type reflection part 5 may be easily worn by rubbing against the original, but since an air layer is formed between the original pressure contact surface 2a and the original, in addition to the effect of the second embodiment. When the original document pressure contact member 2 is opened from the platen 1, the original document does not easily stick to the original document, and when the reflective portion is formed on the original document conveyance belt of the automatic original document feeder, the original document transportability is improved. If the original area is identified in combination with 5, the original can be read more effectively and reliably. The shape of the protrusion may be a dome shape in which a part of the spherical surface is taken out, or may have a corrugated peak if the reflecting surface is oriented in a random direction.

[0058]

According to the present invention, the reflection portion is formed on the original pressure contact surface, and when the portion corresponds to the non-image area, the regular reflection light stronger than the scattered reflection light from the white reference original is imaged. Since it is reflected on the reading member and the presence or absence of the specularly reflected light is detected to discriminate the original area on the platen, the light quantity of the scattered light by the original and the light quantity of the scattered light by the reflecting section are at the same level. Therefore, the original area and the non-original area can be distinguished regardless of the color of the original.

Further, in the present invention, since the reflecting portion is formed on the original pressing surface of the original pressing member and the specular reflection light is reflected by the original reading member by the reflecting portion, an optical element dedicated to identifying the original area is provided. Need not be used, and the structure of the document pressure contact member does not become complicated.

In the image forming apparatus using this document reading apparatus, since the original area and the non-original area can be distinguished regardless of the color of the original, the image data of the original is appropriately selected from the image data of the entire platen. Since the color of the document pressure contact surface can be formed in white, the color of the document pressure contact surface does not cover the image data during the document reading operation, and a proper image can be formed. You can

[Brief description of drawings]

FIG. 1 is a perspective view of a document reading apparatus (standard document identification function) according to a first exemplary embodiment of the present invention.

FIG. 2 is a bottom view of a document pressure contact member used in the document reading apparatus of FIG.

FIG. 3 is an explanatory diagram of specularly reflected light in the document reading apparatus of FIG.

FIG. 4 is a side view of the document reading apparatus of FIG.

FIG. 5 is an explanatory view of specular reflection light in the reduction optical system (in the case of one lamp).

FIG. 6 is an explanatory diagram of specular reflection light in the reduction optical system (in the case of a plurality of lamps).

FIG. 7 is an explanatory view of measures in the reduction optical system of FIG. 6 (when the reflecting surface is inclined).

FIG. 8 is an explanatory diagram of measures in the reduction optical system of FIG. 6 (when dimples are used).

FIG. 9 is a perspective view of an original reading device (an irregular original identifying function and a free registration original identifying function) according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram of the relationship between the size of dimples and regular reflection conditions (Part 1).

FIG. 11 is an explanatory diagram of the relationship between the dimple size and the regular reflection condition (Part 2).

FIG. 12 is an explanatory diagram of regular reflection conditions in the reduction optical system.

FIG. 13 is an explanatory diagram of a specular reflection position on a dimple.

FIG. 14 is an explanatory diagram of a scattered state of illumination light on a dimple during reading.

15 is a configuration diagram of a document area identifying unit in the document reading apparatus of FIG.

FIG. 16 is an explanatory diagram of a detection area in an irregular document identification mode.

FIG. 17 is a determination circuit diagram in the document area identification unit in FIG.

FIG. 18 is an explanatory diagram of a detection area in a free registration document identification mode.

FIG. 19 is an explanatory diagram of a document area edge detection method in a free registration document identification mode.

FIG. 20 is an enlarged cross-sectional view of a reflective portion according to a third embodiment of the present invention.

FIG. 21 is a side view illustrating a conventional document reading apparatus.

[Explanation of symbols]

1: Platen, 2: Original pressing member, 3: Illuminating member, 4:
Image reading member, 5: reflecting portion, and 6: document area identifying means.

Claims (9)

[Claims] 1. A document pressing member for bringing a document placed on a platen into close contact with the platen, and an illumination member for irradiating the document brought into close contact with the platen by the document pressing member.
Scattered reflected light of the reflected light reflected by the original enters,
Further, in a document reading device provided with a position where regular reflected light does not enter and having an image reading member for reading image information of a document included in scattered reflected light, the document contact surface of the document pressure contact member is illuminated. A reflection portion is provided for reflecting the irradiation light from the member so that the specular reflection light is incident on the image reading member. Further, the image reading member is provided with the amount of reflected light incident on the image reading member in advance. A document that is compared using the set reference light amount value, and if the amount of reflected light incident on the image reading member exceeds this reference light amount value, that area is recognized as a non-original area and the original area on the platen is determined. An original reading device characterized by comprising area identifying means. 2. The document reading apparatus according to claim 1, wherein the document area identifying means compares the light amount of the reflected light incident on the image reading member in a predetermined area with a reference light amount value. 3. When the fixed original is arranged on the platen and the fixed original is pressed by the original pressing member, the reflecting portion provided on the original pressing surface of the original pressing member changes the size of each fixed original. 3. The document reading device according to claim 1, wherein the document reading device is arranged so as to generate specularly reflected light in a pattern unique to the. 4. The document reading device according to claim 1, wherein the shape of the reflecting portion is a hollow shape. 5. The reflecting portion provided on the original contact surface of the original pressing member is a large number of dimples having a diameter of 0.5 to 10 mm, which are discretely provided on the entire original contact surface. Alternatively, the document reading device according to item 2. 6. The distance between the dimples is 0.5 to 10
The document reading device according to claim 5, wherein the document reading device has a size of mm. 7. The document reading device according to claim 1, the image information read by an image reading member of the document reading device, and the document area information determined by the document area identifying means. An image forming apparatus comprising: an image processing unit for performing image processing by means of image processing; and an image forming unit for forming an image based on the image data processed by the image processing unit. 8. A diameter of 0.5 to 10 mm on the entire surface of the original contacting surface.
7. The document reading device according to claim 1 and claim 7 to 8, wherein a large number of dimples are discretely provided.
The platen cover according to any one of 1. 9. The distance between the dimples is 0.5 to 10.
The platen cover according to claim 8, having a size of mm.