JP6690597B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading device and an image forming device that read image data of a document.

  A transparent fluorescent paint is applied to the pressure plate that holds the original placed on the contact glass, and the size of the original is detected based on the reflected light of infrared light emitted toward the original from the lower side of the contact glass. There is known a document size detecting device that does (see Patent Document 1, for example).

JP, 11-24185, A

  However, the document size detection device requires a configuration and operation for detecting the amount of infrared light. Therefore, when the technique of the document size detecting device is applied to the image reading device, the cost of the image reading device is increased and the productivity is reduced.

  An object of the present invention is to provide an image reading apparatus and an image forming apparatus capable of detecting an edge of a document while suppressing an increase in cost and a decrease in productivity.

  An image reading device according to one aspect of the present invention includes a transparent glass, a background plate, a light source, an imaging unit, and a detection processing unit. The transparent glass has a first main surface and a second main surface. The background plate is arranged on the first main surface side with respect to the transparent glass, and is coated with a fluorescent substance. The light source is arranged on the second main surface side with respect to the transparent glass, and emits white light toward the background plate. The image capturing unit reads image data including an image of a document located between the first main surface and the background plate based on the reflected light of the white light. The detection processing unit detects an edge of the document in the image data based on a pixel value of a specific color component in the image data.

  An image forming apparatus according to one aspect of the present invention includes the image reading device and an image forming unit. The image forming unit forms an image on a sheet based on image data of a document read by the image reading device.

  According to the present invention, there are provided an image reading apparatus and an image forming apparatus capable of detecting an edge of a document while suppressing an increase in cost and a decrease in productivity.

FIG. 1 is a schematic sectional view showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing the system configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a schematic sectional view showing a part of the configuration of the ADF and the image reading unit in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of document data read by the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a diagram showing the amount of light of each color included in the reflected light in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a flowchart showing an example of the procedure of adjustment processing executed by the image forming apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments are examples of embodying the present invention and do not limit the technical scope of the present invention.

[Configuration of Image Forming Apparatus 10]
First, the configuration of the image forming apparatus 10 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3. Here, FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus 10. FIG. 3 is a schematic sectional view showing a part of the configuration of the ADF 1 and the image reading unit 2.

  The image forming apparatus 10 is a multi-function peripheral having a scan function of reading image data from a document, a print function of forming an image based on the image data, and a plurality of functions such as a facsimile function and a copy function.

  As shown in FIGS. 1 and 2, the image forming apparatus 10 includes an ADF (automatic document feeder) 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, a control unit 5, and an operation display unit 6. Equipped with.

  The image forming unit 3 can form an image by an electrophotographic method based on the image data. Specifically, the image forming unit 3 includes a photoconductor drum, a charging device, an optical scanning device, a developing device, a transfer device, a cleaning device, a fixing device, and a paper discharge tray. The sheet feeding unit 4 includes a sheet feeding cassette, a sheet conveying path, and a plurality of conveying rollers, and supplies a sheet to the image forming unit 3. The image forming unit 3 can form an image based on the image data of the document read by the image reading unit 2 on the sheet supplied from the paper feeding unit 4. The sheet on which the image is formed by the image forming unit 3 is discharged to the paper discharge tray. The image forming unit 3 may form an image by another image forming method such as an inkjet method.

  The control unit 5 includes control devices such as a CPU, a ROM, a RAM, and an EEPROM (registered trademark), which are not shown. The CPU is a processor that executes various arithmetic processes. The ROM is a non-volatile storage medium in which information such as a control program for causing the CPU to execute various processes is stored in advance. The RAM is a volatile storage medium, and the EEPROM is a non-volatile storage medium. The RAM and the EEPROM are used as a temporary storage memory (work area) for various processes executed by the CPU. In the control unit 5, the CPU executes various control programs stored in advance in the ROM. As a result, the image forming apparatus 10 is comprehensively controlled by the control unit 5. The control unit 5 may be configured by an electronic circuit such as an integrated circuit (ASIC), and is a control unit provided separately from the main control unit that integrally controls the image forming apparatus 10. May be.

  The operation display unit 6 is a display unit such as a liquid crystal display that displays various kinds of information according to a control instruction from the control unit 5, and an operation key or a touch panel that inputs various kinds of information to the control unit 5 according to a user operation. Has an operation unit such as.

  The ADF 1 conveys a document to be read (that is, a document whose image data is read by the image reading unit 2). Specifically, as shown in FIGS. 1 and 3, the ADF 1 includes a document transport path 1A, a document placing section 11, a plurality of transport rollers 12, a transport guide 13, and a paper discharge section 14. Further, the ADF 1 is supported so as to be openable and closable with respect to a document table 21 described later, and also serves as a document cover for a document placed on the first contact glass 211 of the document table 21.

  In the ADF 1, each of the transport rollers 12 is driven by a motor (not shown). As a result, the original placed on the original placing portion 11 is conveyed along the original conveying path 1A formed inside the ADF 1. The document conveyed along the document conveyance path 1A is guided to the reading position P1 (see FIG. 3) on the second contact glass 212 of the document table 21 by the conveyance guide 13 and then ejected to the paper ejection unit 14. . Here, the ADF 1 is an example of the document transporting unit in the present invention. Further, the document transport path 1A is an example of the transport path in the present invention.

  The image reading unit 2 can read image data from a document. Specifically, as shown in FIGS. 1 and 3, the image reading unit 2 includes a document table 21, a reading unit 22, a mirror 23, a mirror 24, an optical lens 25, and a CCD 26.

  The document table 21 is provided on the upper surface of the housing of the image forming apparatus 10. As shown in FIGS. 1 and 3, the document table 21 includes a first contact glass 211, a second contact glass 212, and a white reference plate 213. The first contact glass 211 and the second contact glass 212 are transparent glass. A document is placed on the first contact glass 211. The second contact glass 212 is provided at a position facing the conveyance guide 13 of the ADF 1 that is closed with respect to the document table 21. As shown in FIG. 3, the white reference plate 213 is provided on the upper surface of the end of the first contact glass 211 on the second contact glass 212 side. The surface of the white reference plate 213 facing the first contact glass 211 is white.

  The image reading unit 2 can read image data from a document by two different reading methods. Specifically, the image reading unit 2 can read image data from a document placed on the first contact glass 211. The image reading unit 2 can also read image data from the original when the original is conveyed by the ADF 1 through the reading position P1 on the second contact glass 212. Here, the 1st contact glass 211 or the 2nd contact glass 212 is an example of the transparent glass in the present invention. The upper surface of the first contact glass 211 or the second contact glass 212 corresponds to the first main surface of the present invention, and the lower surface of the first contact glass 211 or the second contact glass 212 corresponds to the second main surface of the present invention. To do.

  The reading unit 22 is provided below the document table 21. The reading unit 22 is configured to be movable in the sub-scanning direction (horizontal direction in FIG. 1) by a moving mechanism (not shown) having a driving unit such as a stepping motor. The reading unit 22 includes a light source 221 and a mirror 222, as shown in FIG. The light source 221 is a plurality of white LEDs arranged along the main scanning direction perpendicular to the paper surface of FIG. The light source 221 emits white light for one line in the main scanning direction toward the document table 21. The light emitted from the light source 221 passes through the first contact glass 211 or the second contact glass 212, and is applied to the original placed on the first contact glass 211 or the original conveyed by the ADF 1. The mirror 222 reflects the light emitted from the light source 221 and reflected by the document to the mirror 23.

  In the image reading unit 2, when the image data is read from the document placed on the first contact glass 211, the reading unit 22 is moved to a position below the first contact glass 211 by the moving mechanism. As a result, the light emitted from the light source 221 passes through the first contact glass 211 and is applied to the document placed on the first contact glass 211. Further, the reading unit 22 is moved in the sub scanning direction by the moving mechanism. As a result, the light emitted from the light source 221 onto the document is scanned in the sub-scanning direction.

  Further, in the image reading unit 2, when the image data is read from the document conveyed by the ADF 1, the reading unit 22 is moved to a position below the second contact glass 212 by the moving mechanism. Specifically, the reading unit 22 is moved to a position where the light emitted from the light source 221 passes the reading position P1 (see FIG. 3) by the moving mechanism. As a result, the light emitted from the light source 221 passes through the second contact glass 212, and is irradiated onto the document conveyed by the ADF 1 after passing through the reading position P1.

  In the image reading unit 2, when the image data is read from the white reference plate 213, the reading unit 22 is moved to a position below the white reference plate 213. As a result, the light emitted from the light source 221 passes through the first contact glass 211 and is radiated on the white reference plate 213 provided on the first contact glass 211.

  The mirror 23 reflects the light reflected by the mirror 222 of the reading unit 22 to the mirror 24. The mirror 24 reflects the light reflected by the mirror 23 to the optical lens 25. The optical lens 25 collects the light reflected by the mirror 24 and makes the light incident on the CCD 26.

  The CCD 26 is an image sensor having a plurality of photoelectric conversion elements arranged along the main scanning direction. The CCD 26 outputs an electric signal according to the amount of received light. In the image reading unit 2, the reflected light emitted from the light source 221 and reflected by the document is incident on the CCD 26 via the mirror 222, the mirror 23, the mirror 24, and the optical lens 25. The CCD 26 outputs an electric signal according to the amount of light of each color component of R component (red component), G component (green component), and B component (blue component) contained in the reflected light. Thus, the CCD 26 outputs an analog electric signal of each color component corresponding to the image of the original. The analog electric signal of each color component output from the CCD 26 is converted into a digital electric signal (image data) of each color component by an analog front end circuit (not shown), and is input to the control unit 5. Here, the CCD 26 and the analog front end circuit are examples of the image pickup unit of the present invention. In the image data, each color in each pixel is represented by a pixel value of 256 gradations of 0 (lower limit value) to 255 (upper limit value).

  By the way, a transparent fluorescent paint is applied to the pressure plate (original cover) that holds the original placed on the contact glass (first contact glass 211), and the red light radiated toward the original from the lower side of the contact glass. There is known a document size detection device that detects the size of a document based on the reflected light of external light. However, the document size detection device requires a configuration and operation for detecting the amount of infrared light. Therefore, if the technique of the document size detecting apparatus is applied to the image forming apparatus 10 according to this embodiment, the cost of the image forming apparatus 10 increases and the productivity decreases. On the other hand, according to the image forming apparatus 10 according to the present exemplary embodiment, as described below, it is possible to detect the edge of the document while suppressing an increase in cost and a decrease in productivity.

  In the image forming apparatus 10 according to this embodiment, the transport guide 13 is coated with a fluorescent substance. Here, the transport guide 13 is an example of the background plate in the present invention. The fluorescent substance is a substance that, when irradiated with light having a specific wavelength (excitation wavelength), absorbs the light having the specific wavelength and emits light having a wavelength (fluorescent wavelength) longer than the specific wavelength. In the present embodiment, the transport guide 13 is coated with a fluorescent substance that mainly absorbs light other than red (for example, blue or green light) and mainly emits red light.

  As shown in FIG. 2, the control unit 5 includes a detection processing unit 51, an adjustment processing unit 52, a replacement processing unit 53, and a correction processing unit 54. The control unit 5 functions as each of these processing units by executing various processes according to the control program. Further, the control unit 5 may include an electronic circuit that realizes a part of these processing units or a plurality of processing functions. Here, the device including the ADF 1, the image reading unit 2, and the control unit 5 is an example of the image reading device in the present invention. The present invention can be applied to an image reading device or an image forming device such as a scanner device, a facsimile device, and a copying machine.

  The detection processing unit 51 detects the edge of the document in the image data based on the pixel value of the specific color component in the image data read by the image reading unit 2. The specific color component is specifically a color component corresponding to the fluorescence wavelength of the fluorescent substance. In this embodiment, the transport guide 13 is coated with a fluorescent substance having a fluorescent wavelength of red light. In this case, the detection processing unit 51 detects the edge of the document in the image data based on the pixel value of the red color component in the image data read by the image reading unit 2.

  Hereinafter, the edge detection method by the detection processing unit 51 will be specifically described with reference to FIGS. 4 and 5.

  FIG. 4 shows an example of the image data D1 read by the image reading unit 2. The left-right direction of the image data D1 corresponds to the direction orthogonal to the document conveyance direction (the main scanning direction), and the up-down direction of the image data D1 corresponds to the document conveyance direction (the sub-scanning direction). The image data D1 includes the image of the document conveyed by the ADF1. An area A1 shown in FIG. 4 is an area showing an image of an original (that is, an area inside the original), and an area A2 is an area showing an image of the conveyance guide 13 (that is, an area outside the original). The boundaries between the areas A1 and A2 are the edges E1 to E4 of the document.

  In this embodiment, the light source 221 emits white light toward the document. As shown in FIG. 5A or FIG. 5B, the white light includes red irradiation light R1, green irradiation light G1, and blue irradiation light B1. The white light is reflected by the document or the transport guide 13, and the reflected light is applied to the CCD 26. The reflected light includes red reflected light R2, green reflected light G2, and blue reflected light B2.

  The amounts of the red reflected light R2, the green reflected light G2, and the blue reflected light B2 included in the reflected light change according to the color of the original, but when the white light is reflected by a white original, the As shown in (a), the red reflected light R2, the green reflected light G2, and the blue reflected light B2 have substantially the same light amount. The lengths of the arrows corresponding to the red reflected light R2, the green reflected light G2, and the blue reflected light B2 in FIG. 5 schematically represent the respective light amounts.

  On the other hand, when the white light is reflected by the transport guide 13, the light amount balance of the red reflected light R2, the green reflected light G2, and the blue reflected light B2 is balanced by the action of the fluorescent material applied to the transport guide 13. Change. In the present embodiment, the transport guide 13 is coated with a fluorescent substance that mainly absorbs light other than red light (for example, ultraviolet light, blue light, or green light) and mainly emits red light. Therefore, when the white light is reflected by the transport guide 13, the light amount of the red reflected light R2 is larger than that when the white original is reflected, as shown in FIG. 5B. On the other hand, the amounts of the green reflected light G2 and the blue reflected light B2 are smaller than those when reflected by a white original.

  As described above, when the white light is reflected by the transport guide 13, the light amount of the red reflected light R2 is larger than when the white light is reflected by the white document. Therefore, the detection processing unit 51 can determine whether each pixel is a pixel inside the document or a pixel outside the document based on the pixel value of the red component of each pixel in the image data D1. Therefore, the detection processing unit 51 can detect the edges E1 to E4 of the document in the image data D1.

  The detection processing unit 51 determines that the pixel is located outside the document when the pixel value of the red component of each pixel in the image data D1 is within a predetermined range. For example, the detection processing unit 51 may determine that the pixel is located outside the document when the pixel value of the red component of each pixel in the image data D1 is equal to or greater than a predetermined specific value. The specific value may be a value that is larger than the pixel value of the red component in the image data when the white document is read by the image reading unit 2. For example, when the pixel value of the red component in the image data when a white original is read is 245, the specific value may be 246 or more. The specific value may be an upper limit value of the pixel value (that is, 255).

  In the adjustment processing unit 52, in the image data of the white reference plate 213 read by the image reading unit 2, the pixel value of the specific color component (that is, the red component) becomes the upper limit value, and the image is read by the image reading unit 2. In the image data of the guide 13, the light amount of the light source 221 is adjusted so that the pixel value of the specific color component (that is, the red component) becomes less than the upper limit value. As a result, the detection processing unit 51 determines, for example, in the image data D1 shown in FIG. 4 that the pixel having a red component pixel value of 255 is a pixel outside the document, and the red component pixel value is 255. Pixels that are less than can be determined to be pixels within the document. Therefore, the detection processing unit 51 can detect the edges E1 to E4 of the document in the image data D1.

  By the way, as described above, when the white light is reflected by the conveyance guide 13, the light amount of the red reflected light R2 is larger than that when the white light is reflected by the white original, and the green reflected light G2 and the blue reflected light are reflected. The amount of light B2 becomes smaller. Therefore, in the image data D1 shown in FIG. 4, the area A2 outside the document shows a reddish color (that is, the color of the fluorescent substance applied to the conveyance guide 13). When an image is formed on the sheet in the image forming unit 3 based on the image data D1 as described above, the area outside the document may be colored with the specific color component. For example, if the size of the sheet is larger than the size of the document, or if the document is tilted even if the size of the sheet and that of the document are the same, the color of the specific color component is displayed in the area outside the document on the sheet. Attach.

  Therefore, in order to prevent the above-mentioned coloring, the pixel value of the pixel included in the area A2 may be replaced with, for example, a pixel value indicating white or a pixel value indicating transparency. For example, when the pixel value of the specific color component (that is, the red component) is the upper limit value (that is, 255) for each pixel of the image data, the replacement processing unit 53 determines the remaining color component (that is, the red component). , Blue component and green component) may be replaced with the upper limit value. As a result, with respect to the pixel having the pixel value of the red component of 255 (that is, the pixel located outside the document), the pixel values of the blue component and the green component are replaced with 255, and thus the pixel of the pixel included in the area A2. The value becomes a pixel value indicating white. Accordingly, when an image is formed on a sheet in the image forming unit 3 based on the image data, it is possible to prevent the area outside the document from being colored with the specific color component.

  The correction processing unit 54 performs rotation correction on the image data based on the inclination of the edge of the document detected by the detection processing unit 51. For example, the correction processing unit 54 sets the coordinates (x1, y1) of the intersection C1 of the edges E1 and E2 in the image data D1 shown in FIG. 4 and the coordinates (x2, y2) of the intersection C2 of the edges E2 and E3. To calculate. Then, the correction processing unit 54 calculates the inclination of the edge E2 (that is, the inclination of the document) based on the coordinates of the intersection C1 and the intersection C2, and the coordinate C3 of the middle point C3 between the intersection C1 and the intersection C2 ( x3, y3) is calculated. Then, the correction processing unit 54 performs rotation correction on the image data D1 such that the inclination of the edge E2 is horizontal with the center point C3 as the center.

[Adjustment processing]
Next, an example of the procedure of the adjustment process executed by the control unit 5 (adjustment processing unit 52) will be described with reference to FIG. Here, steps S1, S2, ... Show the numbers of the processing procedures (steps) executed by the control unit 5. The adjustment process is started, for example, when the power of the image forming apparatus 10 is turned on. Alternatively, the adjustment process may be started in response to a predetermined adjustment start operation. Alternatively, the adjustment process may be started when the image reading operation by the image reading unit 2 is started. The adjustment process is executed in the state where the document is not conveyed by the ADF 1.

<Step S1>
First, in step S1, the control unit 5 controls the moving mechanism to move the reading unit 22 to a position below the white reference plate 213.

<Step S2>
In step S2, the control unit 5 sets the gain for amplifying the analog electric signal of each color component output from the CCD 26 to an initial value (for example, 1).

<Step S3>
In step S3, the control unit 5 supplies a current to the light source 221 to turn on the light source 221.

<Step S4>
In step S4, the control unit 5 presets the pixel value of any color component in the image data based on the image data read by the image reading unit 2 (that is, the image data of the white reference plate 213). The supply current of the light source 221 is adjusted so as to reach the target value. The target value is an arbitrary value larger than 0 and smaller than 255, and is 200, for example. In this case, the control unit 5 gradually increases the supply current of the light source 221 until the pixel value of any color component in the image data reaches 200. Then, for example, when the pixel value of the green component reaches 200, the process proceeds to step S5.

<Step S5>
In step S5, the control unit 5 maintains the supply current adjusted in step S4 and maintains the supply current adjusted in step S4 so that the pixel values of all the color components in the image data become the target values (for example, 200). Adjust the gain of. For example, when the pixel value of the green component reaches 200 in step S4, the red gain and the blue gain are gradually increased until the pixel values of the red component and the blue component reach 200. Then, when the pixel values of the red component and the blue component reach 200, the process proceeds to step S6.

<Step S6>
In step S6, the control unit 5 controls the moving mechanism to move the reading unit 22 to a position below the second contact glass 212.

<Step S7>
In step S7, the control unit 5 determines that the pixel value of the red component in the image data is the target value (for example, 200) based on the image data read by the image reading unit 2 (that is, the image data of the transport guide 13). Judgment is made. Then, if it is determined that the pixel value of the red component exceeds the target value (S7: Yes), the process proceeds to step S8. On the other hand, if it is determined that the pixel value of the red color component does not exceed the target value (S7: No), the process returns to step S1.

  Since the transport guide 13 is coated with the fluorescent substance, when the white light emitted from the light source 221 is reflected by the transport guide 13, the white light is reflected by the white reference plate 213 or a white original. The pixel value of the red component becomes larger than that in the case. Therefore, if the supply current of the light source 221 and the gain of each color are adjusted so that the pixel value of the red component becomes 200 in the processing of steps S1 to S5, unless there is a particular abnormality, the image data is obtained in step S7. It is determined that the pixel value of the red color component in is over 200.

<Step S8>
In step S8, the control unit 5 causes the pixel value of the red component in the image data to be the upper limit value (for example, 255) based on the image data read by the image reading unit 2 (that is, the image data of the transport guide 13). The supply current of the light source 221 is adjusted so that For example, the control unit 5 gradually increases the supply current of the light source 221 until the pixel value of the red component in the image data reaches 255. Then, when the pixel value of the red component reaches 255, the process proceeds to step S9.

<Step S9>
In step S9, the control unit 5 controls the moving mechanism to move the reading unit 22 to a position below the white reference plate 213.

<Step S10>
In step S10, the control unit 5 determines, based on the image data read by the image reading unit 2 (that is, the image data of the white reference plate 213), that the pixel value of the red component in the image data is the upper limit value (for example, 255). ) Is less than or equal to. Then, if it is determined that the pixel value of the red component is less than the upper limit value (S10: Yes), the process proceeds to step S11. On the other hand, if it is determined that the pixel value of the red color component is the upper limit value (S10: No), the process returns to step S7.

<Step S11>
In step S11, the control unit 5 stops the supply of current to the light source 221 and turns off the light source 221.

<Step S12>
In step S12, the control unit 5 stores the adjusted set value (that is, the adjusted gain in step S5 and the adjusted supply current in step S8) in the nonvolatile storage medium such as the EEPROM. To do. Then, the adjustment process ends.

  The set value stored in step S12 is used when the image reading unit 2 reads the image data of the document. By using the set value, the pixel value of the specific color component (for example, red component) of the pixel in the document in the image data read by the image reading unit 2 becomes less than the upper limit value (for example, 255), The pixel value of the specific color component of the pixels outside the document is the upper limit value. Therefore, the control unit 5 can detect the edge of the document in the image data based on the pixel value of the specific color component in the image data.

  As described above, in the image forming apparatus 10 according to this embodiment, the transport guide 13 is coated with the fluorescent substance. Then, based on the pixel value of the specific color component of each pixel in the image data read by the image reading unit 2, it is determined whether the pixel is a pixel inside the document or a pixel outside the document. Therefore, according to the image forming apparatus 10 according to the present embodiment, it is possible to detect the edge of the document while suppressing an increase in cost and a decrease in productivity.

[Modification]
In the present embodiment, the case where the image data is read from the document conveyed by the ADF 1 has been described, but the present invention is also applied to the case where the image data is read from the document placed on the first contact glass 211. It is possible. In this case, the fluorescent substance may be applied to the lower surface of the original cover that covers the first contact glass 211 (for example, the original pressing sheet provided on the lower surface of the ADF 1). Here, the document cover or the document pressing sheet is an example of the background plate in the present invention.

  Further, although the case where the fluorescent wavelength of the fluorescent substance is the wavelength of red light has been described in the present embodiment, the present invention is not limited to this. In another embodiment, the fluorescent wavelength of the fluorescent material may be the wavelength of green light. In this case, the detection processing unit 51 can detect the edge of the document in the image data based on the pixel value of the green component in the image data read by the image reading unit 2. In yet another embodiment, the fluorescent wavelength of the fluorescent substance may be the wavelength of blue light. In this case, the detection processing unit 51 can detect the edge of the document in the image data based on the pixel value of the blue component in the image data read by the image reading unit 2.

10 image forming apparatus 1 ADF
13 Conveyance Guide 2 Image Reading Section 21 Document Plate 211 First Contact Glass 212 Second Contact Glass 213 White Reference Plate 22 Reading Unit 221 Light Source 26 CCD
3 image forming unit 5 control unit 51 detection processing unit 52 adjustment processing unit 53 replacement processing unit 54 correction processing unit 6 operation display unit

Claims (7)

Transparent glass having a first main surface and a second main surface,
A background plate disposed on the first main surface side with respect to the transparent glass and coated with a fluorescent material,
A light source that is disposed on the second main surface side with respect to the transparent glass and irradiates white light toward the background plate;
An image pickup unit that reads image data including an image of a document located between the first main surface and the background plate based on the reflected light of the white light;
A detection processing unit that detects an edge of the document in the image data based on a pixel value of a specific color component in the image data;
Equipped with
The detection processing unit determines that the pixel is located outside the document when the pixel value of the specific color component of each pixel in the image data is within a predetermined specific range,
The detection processing unit, when the pixel value of the specific color component of each pixel in the image data is equal to or higher than the upper value of the pixel value, the pixel is in the image reading apparatus you determined to be located outside the original There
White reference plate,
In the image data of the white reference plate read by the imaging unit, the pixel value of the specific color component becomes the upper limit value, and in the image data of the background plate read by the imaging unit, the pixel of the specific color component Further comprising an adjustment processing unit that adjusts the light amount of the light source so that the value is less than the upper limit value.
Image reading device .   Transparent glass having a first main surface and a second main surface,
  A background plate disposed on the first main surface side with respect to the transparent glass and coated with a fluorescent material,
  A light source that is disposed on the second main surface side with respect to the transparent glass and irradiates white light toward the background plate;
  An image pickup unit that reads image data including an image of a document located between the first main surface and the background plate based on the reflected light of the white light;
  A detection processing unit that detects an edge of the document in the image data based on a pixel value of a specific color component in the image data;
  Equipped with
  The detection processing unit determines that the pixel is located outside the document when the pixel value of the specific color component of each pixel in the image data is within a predetermined specific range,
  The detection processing unit is an image reading apparatus that determines that the pixel is located outside the document when the pixel value of the specific color component of each pixel in the image data is equal to or more than the upper limit value of the pixel value. hand,
  For each pixel of the image data, when the pixel value of the specific color component is the upper limit value, further includes a replacement processing unit that replaces the pixel value of the remaining color component with the upper limit value,
  Image reading device. The specific color component is a color component corresponding to the fluorescence wavelength of the fluorescent substance,
The image reading apparatus according to claim 1 or 2. The fluorescent wavelength of the fluorescent substance is the wavelength of red light,
The specific color component is a red component,
The image reading apparatus according to claim 3 . A correction processing unit that performs rotation correction on the image data based on the inclination of the edge of the document detected by the detection processing unit;
The image reading apparatus according to any one of claims 1-4. The apparatus further includes a document transport unit that transports a document to be read along a transport path,
The background plate is a conveyance guide provided at a reading position of the document in the conveyance path,
The image reading apparatus according to any one of claims 1-5. An image reading apparatus according to any one of claims 1 to 6
An image forming unit that forms an image on a sheet based on image data of a document read by the image reading device;
An image forming apparatus including.

Images