JP2004297450A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus for accurately detecting a size of an original and selecting paper in accordance with the original size even for the original having any wavelength by enhancing the detecting performance of the size of the original. <P>SOLUTION: Inside an image reading apparatus body 1, a sensor 20 is provided for sensing a size of the original 3 in the length direction placed on original platen glass 2, and the sensor 20 is fitted to a support member 19. Further, a CCD sensor 17 provided inside the image reading apparatus body 1 senses the width of the original 3 placed on the original platen glass 2, and the CCD sensor 17 adopts a color imaging system CCD sensor (color image sensor). The color CCD sensor senses the width of the original 3 placed on the original platen glass 2 on the basis of a light receiving amount of incident light color-separated into three primary color lights in red, green and blue. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus using a CCD sensor (charge coupled device) as a reading element, such as a digital copying machine, an image scanner, and a facsimile, and more particularly to detecting a document size using a reading sensor such as a CCD sensor. To an image reading apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, digital copying machines, image scanners, facsimile machines, and the like use a digital reading device that reads a document image using a reading sensor. In this digital reading apparatus, a CCD sensor (charge-coupled device) is used as a reading sensor, and the density of a document image is converted into an electric signal level. In recent years, with the development of digital technology, digital copiers, image scanners, facsimile machines and the like have also realized higher speed and higher accuracy, and accordingly, the reading speed of the image reading unit in the image reading device has also been increased. It has been sped up.
[0003]
The scanning optical system moves the light source parallel to the document surface at a constant scanning speed, and scans the light reflected from the document surface to form an image on the CCD unit by the imaging lens. The original document is illuminated with a slit by a light source, and the reflected light is reflected by a first mirror in parallel to the document surface, reflected in opposite directions through second and third mirrors orthogonal to each other, and is reflected on a CCD sensor by an imaging lens. The one configured to form an image is generally adopted.
[0004]
Here, in an image forming apparatus using such a digital image reading device, it is necessary to accurately detect a document size and to select a sheet according to the document size, and in a conventional image reading device, For example, a photo sensor for detecting the length of the document is provided in correspondence with the contact glass on which the document is set, and a CCD sensor for detecting the width of the document is provided. Based on information from the two sensors, the size of the document is determined. A device to detect is disclosed (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-5-207239 (pages 2-4, FIG. 1-3)
[0006]
[Problems to be solved by the invention]
However, in the above-described image reading apparatus, since a monochrome CCD sensor (monochrome image sensor) is used as a CCD sensor for detecting a document, information (that is, color information) corresponding to the wavelength of light can be obtained. Since the wavelength range that can be read by the CCD sensor is limited to the wavelength range (490 to 570 nm) of green light emitted by a green lamp generally used as a light source, wavelengths outside the wavelength range cannot be used. Cannot be detected. Therefore, in the above-described conventional image reading apparatus, it has been difficult to accurately detect the size of the colored original and select a sheet according to the original size.
[0007]
The present invention solves the above problems and improves the detection performance of the document size, thereby accurately detecting the size of the document with respect to a document having any wavelength, and forming a sheet according to the document size. It is an object of the present invention to provide an image reading device capable of selecting the image reading device.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a CCD sensor which is configured to further reflect, by a mirror, irradiation light irradiated by a light source and reflected by a document, and via an imaging lens provided to face the CCD sensor. In the image reading apparatus which forms the image on the CCD sensor, the CCD sensor is a color CCD sensor. The color CCD sensor detects the width of the document and is provided at a predetermined position in the image reading apparatus main body. The size of the document is determined by detecting the size of the document in the longitudinal direction by the sensor.
[0009]
Here, in the present invention, in a state where the light source is turned on, the light source is moved by a predetermined distance in a scanning direction or a return direction from a predetermined document size detection position, and a plurality of irradiation lights reflected by the document are sent to the color CCD sensor. By making the light incident, the width size of the document can be detected.
[0010]
Further, in the present invention, the color CCD sensor includes a light receiving amount based on irradiation light that is color-separated into red, green, and blue primary color lights incident on the color CCD sensor, and a predetermined light receiving amount. By comparing the threshold values, the width size of the document can be detected.
[0011]
In the present invention, the color CCD sensor includes a red detection CCD sensor for detecting red light, a green detection CCD sensor for detecting green light, and a blue detection CCD sensor for detecting blue light. In this case, the largest size of the document width sizes detected by the red, green, and blue detection CCD sensors can be determined as the document width size.
[0012]
In the present invention, when the width size of the document is detected by at least one of the red, green, and blue detection CCD sensors, the width size detected by at least one CCD sensor is determined. The width size of the document can be determined.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram illustrating an external configuration of an image reading apparatus according to an embodiment of the present invention. In FIG. 1, an image reading device 50 supports an image reading device main body 1, a platen glass 2 provided on an upper surface of the image reading device main body 1, and a document 3 placed on the platen glass 2. The original cover 4 allows the original 3 to be uniformly pressed against the original platen glass 2. The document cover 4 is supported by a document cover supporting portion 5 provided on the side of the image reading apparatus main body 1 so as to be openable and closable in a vertical direction. The document cover supporting portion 5 may be provided inside the image reading apparatus main body 1 to support the document cover 4 so that the document cover 4 can be opened and closed in the vertical direction.
[0014]
The document cover support 5 is provided with a sensor 6 for detecting the open / close state of the document cover 4, and a document cover open / close detection provided between the image reading apparatus main body 1 and the document cover support 5. A switch is constituted by the auxiliary member 7 for use and the sensor 6.
[0015]
That is, as shown in FIG. 1, the upper end portion 7b of the auxiliary member 7 is in contact with the document cover 4 so that the auxiliary member 7 moves up and down in conjunction with opening and closing of the document cover 4. Has become. Further, as shown in FIG. 2, the sensor 6 has a light emitting element 8 composed of a light emitting diode that emits infrared rays and the like, and a light receiving element 9 composed of a photodiode. When the document cover 4 is in the open state (ie, the state shown in FIG. 1), the protrusion 7a formed on the auxiliary member 7 is in the state of 7a shown by a solid line in FIG. Although the light emitting element 8 and the light receiving element 9 are in a light-shielding state (that is, in a switch OFF state), when the document cover 4 is gradually closed and the auxiliary member 7 moves downward in conjunction with this, the auxiliary member 7 The protrusion 7a formed on the light-emitting element 8 also moves downward, and becomes a state 7a 'shown by a dotted line in FIG. 2, and the light-shielding state of the light emitting element 8 and the light receiving element 9 is released (that is, the switch is ON), and the optical signal Is generated.
[0016]
FIG. 3 is a schematic diagram illustrating the entire configuration of the image reading apparatus according to the embodiment of the present invention. In FIG. 3, an image reading apparatus main body 1 includes a light source 10 that illuminates a document 3 by irradiating the document 3 placed on a document table glass 2 with light, and reflects an irradiation light reflected by the document 3 in a 90-degree direction. A first optical system unit 12 composed of a first mirror 11 that performs reflection, a second mirror 13 that reflects light reflected by the first mirror 11 in the direction of 90 degrees, and a light reflected by the second mirror 13 in the direction of 90 degrees. And a third optical system unit 15 composed of a third mirror 14 that reflects the light.
[0017]
An image forming lens 16 and a CCD unit 18 on which a CCD sensor 17 is mounted are provided inside the image reading apparatus main body 1. The light reflected from the original 3 by the third mirror 14 is reflected by the third mirror 14. The light is converged by the imaging lens 16 provided facing the CCD sensor 17, enters the CCD sensor 17 via the imaging lens 16, and is imaged on the CCD sensor 17. Then, the light of the image scanned on the original 3 is converted into an electric signal by the CCD sensor 17, and the density of the original image is converted into a high or low electric signal level.
[0018]
Further, in the above configuration, the image forming lens 16 and the CCD sensor 17 are fixed to the image reading apparatus main body 1. However, even if the light source 10 moves in the scanning direction, the original-side optical path length does not change. The first optical unit 12 composed of the light source 10 and the first mirror 11 and the second optical unit 15 composed of the second mirror 13 and the third mirror 14 are each movable at a constant speed. It is provided so that it becomes.
[0019]
A sensor 20 for detecting the size of the original 3 placed on the original platen glass 2 in the longitudinal direction is provided at a predetermined position in the image reading apparatus main body 1 according to the present embodiment. Reference numeral 20 is attached to the support member 19. As shown in FIG. 4, the sensor 20 is located after the maximum size of the document which can be set on the platen glass 2 in the horizontal direction (A4 size in FIG. 4) when viewed from above the platen glass 2. When the original 3 placed along the leading edge registration line X and the side registration line Y is vertically fed with respect to the edge detection position, and is slightly larger than the A5 size. Are detected by the sensor 20. Conversely, when the document is fed horizontally, the A4 size document which is the maximum size of the fed document is not detected by the sensor 20. Accordingly, it is detected that the original document detected by the sensor 20 is placed on the original platen glass 2 in the vertical feed state. In the present embodiment, the size of the document 3 placed on the document table glass 2 in the longitudinal direction is detected in this manner.
[0020]
The CCD sensor 17 provided inside the image reading apparatus main body 1 detects the width of the document 3 placed on the platen glass 2. , A color imaging CCD sensor (color image sensor) is used. This color CCD sensor is, for example, a three-plate type that performs color separation of incident light using three CCD sensors and a color separation prism (dichroic prism) to obtain information corresponding to red, green, and blue primary color light. Or a single-plate (simultaneous) color CCD sensor having a color filter array corresponding to each pixel on the surface of the CCD sensor. In the present embodiment, a description will be given below, taking a three-plate type color CCD sensor as an example.
[0021]
When a three-plate CCD sensor is used, the CCD 17 in the present embodiment includes a red detection CCD sensor that generally detects red light having a wavelength range of 580 to 700 nm and a green light that generally has a wavelength range of 490 to 570 nm. It comprises a green detection CCD sensor for detecting, and a blue detection CCD sensor for detecting blue light generally having a wavelength region of 400 to 480 nm (both are not shown). Each of these three CCD sensors is placed on the platen glass 2 based on the amount of incident light that has been color-separated into three primary colors of red, green, and blue by a color separation prism (not shown). The width size of the document 3 is detected. More precisely, the charge amount (analog signal) based on the amount of light received by each CCD sensor is converted into a digital signal, and the width size of each of the three CCD sensors is detected based on the digital signal.
[0022]
More specifically, incident light that is reflected by the third mirror 14, converged by the imaging lens 16, and color-separated into three primary colors of red, green, and blue by the color separation prism (irradiation from the original 3) The light) enters the three CCD sensors. At this time, each CCD sensor detects the width size of the document 3 using a predetermined threshold value determined in advance. That is, when the maximum light receiving amount in each CCD sensor is 100%, a line having a light receiving amount (threshold) of 30% is determined as a boundary line (edge) of the document, and the width size of the document 3 is detected. In other words, by comparing the amount of incident light of each color (irradiation light reflected by the original 3) incident on each CCD sensor with a predetermined threshold value determined in advance for the amount of received light, the boundary of the original 3 is determined. The line (edge) is determined, and the width size of the document 3 is detected. Then, among the width sizes of the document 3 detected by each of the three CCD sensors, the largest size is determined as the width size of the document 3.
[0023]
For example, when the width size detected by the red detection CCD sensor is B4, and the width sizes detected by the green detection blue sensor and the blue detection CCD sensor are A4, the largest of the detected width sizes. B4 is determined as the width size of the document 3.
[0024]
Further, for example, it is determined that the boundary line (edge) of the document 3 having the light receiving amount of 30% is not detected (that is, the document does not exist) by the green detection CCD sensor and the blue detection CCD sensor. However, if the remaining red detection CCD sensor detects the boundary line (edge) of the original 3 having the light receiving amount of 30% and determines that the width of the original 3 is B4, the B4 size is determined to be the original. 3 is determined as the width size. In this embodiment, when the width of the document 3 is detected by at least one of the three CCD sensors, the width of the document 3 is detected by the at least one CCD sensor. Since at least one CCD detects the width size of the document 3, the width size of the colored document can be accurately detected in the entire wavelength band of the color CCD sensor because at least one CCD detects the width size of the document 3. Can be done.
[0025]
FIG. 5 is a flowchart showing a procedure for determining the document size. In this procedure, first, the document cover 4 is opened (step S1), the auxiliary member 7 is moved upward in conjunction with the document cover 4, the light emitting element 8 and the light receiving element 9 are set in a light-shielding state, and the sensor 6 is turned on. The switch is turned off (step S2). Then, the first optical system unit 12 and the second optical system unit 15 move to a predetermined document size detection position (home position) (step S3). Next, the original 3 is set on the original platen glass 2 (step S4), the original cover 4 is closed (step S5), and the auxiliary member 7 is moved downward in conjunction with the original cover 4 to emit light. 8 and the light receiving element 9 are released from the light blocking state, and the sensor 6 is turned on (step S6).
[0026]
When the switch of the sensor 6 is turned on, the light source 10 is turned on for a short time (for example, 10 msec) (Step S7), and the irradiation light reflected by the document 3 is reflected by the first optical system unit 12, the second optical system unit 15, After passing through the imaging lens 16, the color separation prism separates the light into three primary colors of red, green and blue, and the reflected light constitutes a CCD sensor 17 (in the present embodiment, as described above, a color CCD sensor). To the three CCD sensors described above. Next, in each of the red, green and blue detection CCD sensors, the boundary line (edge) of the document 3 is determined, and the width of the document 3 is detected by each CCD sensor ( Step S8). Next, the largest one of the width sizes detected by the three CCD sensors is determined as the width size of the document 3 (step S9). At this time, as described above, if the width size of the document 3 is detected by at least one of the three CCD sensors, the size detected by the at least one CCD sensor is set as the maximum size and the width of the document 3 is set to the maximum size. Confirm the size. When the width size of the document 3 is detected by two CCD sensors among the three CCDs, the larger size of the sizes detected by the two CCD sensors is set as the maximum size, and the width size of the document 3 is set as the maximum size. Determine. If it is determined that the boundary line (edge) of the document 3 does not exist in any of the three CCD sensors, it is determined that there is no document (step S10).
[0027]
When the switch of the sensor 6 is turned on (step S6), in parallel with the detection of the width size of the document 3 by the three CCD sensors, the longitudinal direction of the document 3 placed on the platen glass 2 by the sensor 20 is detected. Is detected, and the size is determined (step S11). Next, the document size is determined based on the width size of the document 3 determined in step S9 and the longitudinal size of the document 3 determined in step S11 (step S12).
[0028]
It should be noted that the present invention is not limited to the above-described embodiment, and it is possible to appropriately change the structure, shape, and the like of each part based on the gist of the present invention, and exclude them from the scope of the present invention. is not.
[0029]
For example, in the above embodiment, the sensor 6 is turned off (step S2), and the first optical system unit 12 and the second optical system unit 15 are moved to a predetermined document size detection position (home position) (step S2). S3) Although the light source 10 is turned on for a short time (step S7), while the light source 1 is turned on (that is, with the light source 1 turned on), the light source 1 is moved from the home position in the scanning direction or By moving the first optical system unit 12 and the second optical system unit 15 a predetermined distance from the home position in the scan direction or the return direction by a predetermined distance in the return direction, a plurality of irradiation lights reflected by the document 3 May be incident on three CCD sensors constituting the CCD sensor 17. With this configuration, it is possible to obtain a plurality of data regarding the irradiation light incident on the three CCD sensors, and to improve the performance of detecting the width size of the document 3. Therefore, based on the plurality of data, the document 3 can be determined more accurately.
[0030]
【The invention's effect】
As described above, according to the present invention, a color imaging CCD sensor (color image sensor) is used as a CCD sensor for detecting the width of a document placed on a platen glass. If at least one of the constituent red, green and blue detection CCD sensors detects the width of the document, the width of the document can be determined. Further, among the width sizes detected by the red, green, and blue detection CCD sensors, the largest size is determined as the width size of the document. Therefore, information (ie, color information) corresponding to the wavelength of light can be obtained in the entire wavelength band of the color CCD sensor. Can be accurately detected, and a sheet can be selected according to the document size.
[0031]
Further, according to the present invention, the color CCD sensor is provided with a light receiving amount based on the irradiation light color-separated into the three primary colors of red, green and blue incident on the color CCD sensor, and a predetermined light receiving amount. , The width of the document is detected by comparing the thresholds of the color CCD sensors. Even if it occurs, it is possible to accurately detect the size of the document and select a sheet according to the size of the document.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an external configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view for explaining a configuration of a switch in the image reading apparatus according to the embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating an overall configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 4 is a top view for explaining a relationship between a position of a sensor with respect to a platen glass and a document size of the image reading apparatus according to the embodiment of the present invention.
FIG. 5 is a flowchart illustrating a procedure for determining a document size in the image reading apparatus according to the embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 image reading device main body 2 platen glass 4 document cover 5 document cover support 6 sensor 7 auxiliary member 7 a projection 8 light emitting element 9 light receiving element 9
Reference Signs List 10 light source 11 first mirror 13 second mirror 14 third mirror 16 imaging lens 17 CCD sensor 18 CCD unit 20 sensor

Claims (5)

Irradiation light irradiated by the light source and reflected by the original is further reflected by a mirror and incident on the CCD sensor via an imaging lens provided facing the CCD sensor to form an image on the CCD sensor. In the image reading device to be
The CCD sensor is a color CCD sensor, and the width of the document is detected by the color CCD sensor, and the size of the document in the longitudinal direction is detected by a sensor provided at a predetermined position in the image reading apparatus main body. An image reading apparatus for determining the size of the document. With the light source turned on, the light source is moved a predetermined distance in a scan direction or a return direction from a predetermined document size detection position, and a plurality of irradiation lights reflected by the document are made incident on the color CCD sensor. 2. The image reading apparatus according to claim 1, wherein a width size of the document is detected. The color CCD sensor includes a light receiving amount based on the irradiation light, which is color-separated into three primary color lights of red, green, and blue, which are incident on the color CCD sensor, and a predetermined threshold value predetermined with respect to the light receiving amount. 3. The image reading apparatus according to claim 1, wherein the width size of the document is detected by comparison. The color CCD sensor includes a red detection CCD sensor for detecting red light, a green detection CCD sensor for detecting green light, and a blue detection CCD sensor for detecting blue light. 4. The image reading apparatus according to claim 3, wherein a largest one of the widths of the document detected by each of the CCD sensor for detecting blue and blue is determined as the width of the document. When the width size of the document is detected by at least one of the red, green, and blue detection CCD sensors, the width size detected by the at least one CCD sensor is determined by the width of the document. The image reading device according to claim 4, wherein the size is determined as a size.

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