JP3963853B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus such as a digital copying machine, an image scanner, and a facsimile using a CCD sensor (charge coupled device) as a reading element, and in particular, detects a document size using a reading sensor such as a CCD sensor. The present invention relates to an image reading apparatus.
[0002]
[Prior art]
Conventionally, digital copiers, image scanners, facsimile machines, and the like use digital reading devices that read an image of a document by a reading sensor. In this digital reading apparatus, a CCD sensor (charge coupled device) is used as a reading sensor, and the density of an original image is converted into an electric signal level. In recent years, with the development of digital technology, high speed and high accuracy have been realized in digital copying machines, image scanners, facsimile machines, and the like, and accordingly, the reading speed of the image reading unit in the image reading apparatus is also increased. It is faster.
[0003]
A reading optical system that scans by moving the light source parallel to the document surface at a constant scanning speed and forms an image of the reflected light from the document surface on the CCD unit by the imaging lens is placed on a contact glass. The original is slit-irradiated by a light source, the reflected light is reflected by the first mirror in parallel to the surface of the original, reflected by the second and third mirrors orthogonal to each other, and reflected in the reverse direction by the imaging lens on the CCD sensor In general, an image formed so as to form an image is used.
[0004]
Here, in an image forming apparatus using such a digital image reading apparatus, it is necessary to accurately detect a document size and select a sheet according to the document size. In a conventional image reading apparatus, 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, and the size of the document is determined based on information from the two sensors. What is detected is disclosed (for example, refer to Patent Document 1).
[0005]
[Patent Document 1]
JP-A-5-207239 (page 2-4, Fig. 1-3)
[0006]
[Problems to be solved by the invention]
However, since the above-described image reading apparatus uses a monochrome CCD sensor (monochrome image sensor) as a CCD sensor for detecting an original, information corresponding to the wavelength of light (that is, color information) can be obtained. The wavelength range that cannot be read by the CCD sensor is limited to the wavelength range (490 to 570 nm) of green light emitted from a green lamp that is generally used as a light source. It is impossible to detect a colored document having. Therefore, in the conventional image reading apparatus, it is difficult to accurately detect the size of the colored document and select a sheet corresponding to the document size.
[0007]
The present invention solves the above-mentioned problems and improves the document size detection performance, thereby accurately detecting the size of the document for any wavelength, and corresponding to the document size. An object of the present invention is to provide an image reading apparatus capable of selecting the image.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, the irradiation light irradiated by the light source and reflected by the document is further reflected by the mirror, and the CCD is connected via the imaging lens provided facing the CCD sensor. to be incident on the sensor, the image reading apparatus for focusing onto the CCD sensor, the CCD sensor is a color CCD sensor, a CCD sensor for red detection for detecting red light, CCD for green detection for detecting the green light A sensor and a blue detection CCD sensor for detecting blue light, and a received light amount based on the irradiation light that is color-separated into the three primary color lights of red, green, and blue incident on the color CCD sensor; Detecting the width size of the document by comparing a predetermined threshold value determined in advance with respect to the amount of received light, and detecting the red, green, and blue colors Of width size of the original is detected in each of the CCD sensor, and determines the largest size as the width size of the original, by a sensor provided at a predetermined position of the image reading apparatus main body of the document longitudinal The size of the original is determined by detecting the size of the document.
[0009]
In the present invention, in a state in which the light source is lit, the light source by a predetermined distance in the scanning direction or return direction from the predetermined document size detection position, a plurality of radiation beam reflected by the document By making the light incident on the color CCD sensor, the width size of the original can be detected.
[0010]
In the present invention, when the width size of the original is detected by at least one CCD sensor among the red, green and blue detection CCD sensors, the width detected by the at least one CCD sensor. The size may be determined as the width size of the document .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an external configuration of an image reading apparatus according to an embodiment of the present invention. In FIG. 1, an image reading device 50 presses and supports an image reading device main body 1, an original table glass 2 provided on the upper surface of the image reading device main body 1, and an original document 3 placed on the original table glass 2. The document cover 4 is provided so that the document 3 can be pressed uniformly against the document table glass 2. The document cover 4 is supported by a document cover support portion 5 provided on the side of the image reading apparatus main body 1 so as to be opened and closed in the vertical direction. The document cover support portion 5 may be provided inside the image reading apparatus main body 1 so as to support the document cover 4 so that it 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. The auxiliary member 7 and the sensor 6 constitute a switch.
[0015]
That is, as shown in FIG. 1, the upper tip 7 b 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. It has become. As shown in FIG. 2, the sensor 6 includes a light emitting element 8 made of a light emitting diode that emits infrared rays and the like, and a light receiving element 9 made of a photodiode. When the document cover 4 is in the open state (that is, the state shown in FIG. 1), the protrusion 7a formed on the auxiliary member 7 is in the state 7a indicated by the solid line in FIG. Then, 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 protruding portion 7a formed in FIG. 2 also moves downward and enters the state 7a 'shown by the dotted line in FIG. Is generated.
[0016]
FIG. 3 is a schematic diagram showing the overall configuration of the image reading apparatus according to the embodiment of the present invention. In FIG. 3, the image reading apparatus body 1 reflects a light source 10 that illuminates the original by irradiating the original 3 placed on the original table glass 2 and the light reflected by the original 3 in the direction of 90 degrees. A first optical system unit 12 composed of the first mirror 11, a second mirror 13 that reflects the reflected light from the first mirror 11 in the 90-degree direction, and a reflected light from the second mirror 13 in the 90-degree direction. The second optical system unit 15 includes a third mirror 14 that reflects the light.
[0017]
In addition, 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, and reflected light from the document 3 reflected by the third mirror 14 is The light is converged by an imaging lens 16 provided facing the CCD sensor 17, enters the CCD sensor 17 through the imaging lens 16, and forms an image on the CCD sensor 17. Then, the light of the image scanned on the document 3 is converted into an electric signal by the CCD sensor 17, and the density of the document image is converted into the level of the electric signal level.
[0018]
In the above configuration, the imaging lens 16 and the CCD sensor 17 are fixed to the image reading apparatus main body 1. However, in order to prevent the original-side optical path length from changing even if the light source 10 moves in the scanning direction. In addition, 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 can each move at a constant speed. It is provided to become.
[0019]
Further, a sensor 20 for detecting the size in the longitudinal direction of the document 3 placed on the document table glass 2 is provided at a predetermined position in the image reading apparatus main body 1 in the present embodiment. Reference numeral 20 denotes a support member 19. As shown in FIG. 4, the sensor 20 is located after the maximum lateral feed size (A4 size in FIG. 4) of the document that can be set on the document table glass 2 when viewed from above the document table glass 2. When the document 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, the size is larger than the A5 size. All the originals are detected by the sensor 20. Conversely, when the original is laterally fed, the A4 size original, which is the maximum laterally fed size, is not detected by the sensor 20. Therefore, it is detected that the document detected by the sensor 20 is placed on the document table glass 2 in the vertical feed state. In this embodiment, the size in the longitudinal direction of the document 3 placed on the document table glass 2 is detected in this way.
[0020]
The CCD sensor 17 provided in the image reading apparatus main body 1 detects the width of the document 3 placed on the document table glass 2. In the present embodiment, the CCD sensor 17 is connected to the CCD sensor 17. A color imaging CCD sensor (color image sensor) is used. As this color CCD sensor, for example, three CCD sensors and a color separation prism (dichroic prism) are used to perform color separation of incident light and obtain information corresponding to the three primary color lights of red, green and blue. Or a single-plate (simultaneous) color CCD sensor in which a color filter array corresponding to each pixel is provided on the surface of the CCD sensor. In the present embodiment, a description will be given below by taking a three-plate color CCD sensor as an example.
[0021]
When a three-plate type CCD sensor is used, the CCD 17 in this embodiment generally includes a red detection CCD sensor that 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 is comprised of a CCD sensor for detecting green color and a CCD sensor for detecting blue light that generally detects blue light having a wavelength region of 400 to 480 nm (both not shown). Each of these three CCD sensors was placed on the platen glass 2 based on the amount of light received by incident light that was 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 in each of the three CCD sensors is detected based on the digital signal.
[0022]
More specifically, incident light (irradiation from the original 3) reflected by the third mirror 14, converged by the imaging lens 16, and separated into three primary colors of red, green, and blue by the color separation prism. The light is incident on the three CCD sensors. At this time, each CCD sensor detects the width size of the document 3 using a predetermined threshold value. That is, assuming that the maximum received light amount in each CCD sensor is 100%, a line having a received light amount (threshold value) of 30% is determined as a document boundary line (edge), and the width size of the document 3 is detected. That is, by comparing the amount of received light of each color incident on each CCD sensor (irradiated light reflected by the document 3) with a predetermined threshold value determined in advance with respect to the amount of received light, the boundary of the document 3 A line (edge) is determined, and the width size of the document 3 is detected. Then, the largest size among the width sizes of the document 3 detected by each of the three CCD sensors is determined as the width size of the document 3.
[0023]
For example, when the width size detected by the CCD sensor for red detection is B4 and the width size detected by the CCD sensor for green detection and the CCD sensor for blue detection is A4, the largest of the detected width sizes. B4 is determined as the width size of the document 3.
[0024]
Further, for example, in the case where it is determined that the boundary line (edge) of the original 3 having the light receiving amount of 30% is not detected (that is, no original exists) in 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 set to the original. Determined as a width size of 3. In the present embodiment, when the width size of the document 3 is detected by at least one CCD sensor among the three CCDs, the width size detected by the at least one CCD sensor is set to the document 3 in this way. Therefore, if at least one CCD detects the width size of the document 3, the width size of the colored document can be accurately detected in all wavelength bands of the color CCD sensor. Will be able to.
[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 blocked, 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 document 3 is set on the document table glass 2 (step S4), the document cover 4 is closed (step S5), the auxiliary member 7 is moved downward in conjunction with the document cover 4, and the light emitting element. 8 and the light receiving element 9 are released from the light shielding 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 the first optical system unit 12, the second optical system unit 15, Then, 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 the CCD sensor 17 (in this embodiment, as described above, the color CCD sensor). It enters the above-mentioned three CCD sensors. Next, the boundary line (edge) of the document 3 is determined in each of the red detection CCD sensor, the green detection CCD sensor, and the blue detection CCD sensor, and the width size of the document 3 is detected in each CCD sensor ( Step S8). Next, the maximum width size detected by each of the three CCD sensors is determined as the width size of the document 3 (step S9). At this time, as described above, when the width size of the document 3 is detected by at least one CCD sensor among the three CCDs, the width of the document 3 is set to the size detected by the at least one CCD sensor as the maximum size. Determine the size. When the width size of the document 3 is detected by two CCD sensors among the three CCDs, the width size of the document 3 is set to the largest size among the sizes detected by the two CCD sensors. Determine. In any of the three CCD sensors, if it is determined that the boundary line (edge) of the document 3 does not exist, it is determined that there is no document (step S10).
[0027]
When the switch of the sensor 6 is turned on (step S6), the longitudinal direction of the document 3 placed on the document table glass 2 by the sensor 20 in parallel with the detection of the width size of the document 3 by the three CCD sensors. 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 size in the longitudinal direction of the document 3 determined in step S11 (step S12).
[0028]
In addition, this invention is not limited to the said embodiment, Based on the meaning of this invention, it is possible to change suitably the structure of each part, a shape, etc., and excludes them from the scope of the present invention. is not.
[0029]
For example, in the above embodiment, the sensor 6 is switched 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), the light source 10 is turned on for a short time (step S7). A plurality of irradiation lights reflected by the document 3 by moving a predetermined distance in the return direction (that is, moving the first optical system unit 12 and the second optical system unit 15 by a predetermined distance in the scanning direction or the return direction from the home position). May be configured to be incident on the three CCD sensors constituting the CCD sensor 17. With this configuration, it becomes possible to obtain a plurality of data relating to the irradiation light incident on the three CCD sensors, and the detection performance of the width size of the document 3 is improved. Therefore, based on the plurality of data, the document The size of 3 can be determined with higher accuracy.
[0030]
【The invention's effect】
As described above, according to the present invention, a color imaging type CCD sensor (color image sensor) is used as a CCD sensor for detecting the width of a document placed on a platen glass, and the CCD sensor is used as a CCD sensor. If at least one CCD sensor among the red, CCD, and blue color detection CCD sensors constituting the sensor detects the width size of the document, the width size of the document can be determined. Further, the largest size among the width sizes detected by each of the red, green, and blue color detecting CCD sensors is determined as the width size of the original. Therefore, since information (that is, color information) corresponding to the wavelength of light can be obtained in the entire wavelength band of the color CCD sensor, the size of the original can be obtained for a colored original having any wavelength region. Can be detected accurately, and a sheet corresponding to the document size can be selected.
[0031]
Further, according to the present invention, the color CCD sensor has a light reception amount based on the irradiation light that is color-separated into the three primary color lights of red, green, and blue incident on the color CCD sensor, and a predetermined light amount determined in advance. Therefore, the amount of incident light on the color CCD sensor varies due to variations in sensitivity of the color CCD sensor used and variations in light emission from the light source. Even if it occurs, it is possible to accurately detect the size of the document and select a sheet according to the document size.
[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 showing an overall configuration of an image reading apparatus according to an embodiment of the present invention.
FIG. 4 is a top view for explaining the relationship between the position of the sensor and the document size with respect to the document table glass 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]
DESCRIPTION OF SYMBOLS 1 Image reading apparatus main body 2 Original plate glass 4 Original cover 5 Original cover support part 6 Sensor 7 Auxiliary member 7a Protrusion part 8 Light emitting element 9 Light receiving element 9
DESCRIPTION OF SYMBOLS 10 Light source 11 1st mirror 13 2nd mirror 14 3rd mirror 16 Imaging lens 17 CCD sensor 18 CCD unit 20 Sensor

Claims (3)

Irradiation light emitted from the light source and reflected from the document 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, a CCD sensor for red detection for detecting red light, and a CCD sensor for green detection for detecting the green light is constituted by a CCD sensor for blue detection for detecting the blue light By comparing the received light amount based on the irradiation light separated into the three primary color lights of red, green, and blue incident on the color CCD sensor with a predetermined threshold value determined in advance with respect to the received light amount, The width of the original is detected, and the largest of the widths of the original detected by the CCD sensors for detecting red, green, and blue is determined as the width of the original , and the image reading apparatus The size of the document is determined by detecting the size of the document in the longitudinal direction by a sensor provided at a predetermined position in the body. Image reading apparatus according to claim and. In a state in which lights the light source to be incident the light source by a predetermined distance in the scanning direction or return direction from the predetermined document size detection position, a plurality of irradiation light reflected by the document on the color CCD sensor The image reading apparatus according to claim 1, wherein the width size of the document is detected. When at least one CCD sensor among the red, green, and blue detection CCD sensors detects the width of the document, the width detected by the at least one CCD sensor is set to the width of the document. The image reading apparatus according to claim 1, wherein the image reading apparatus is determined as a size .

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