JP6565851B2 - Image reading apparatus, image forming apparatus, and image reading method - Google Patents

Description

  The present invention relates to an image reading apparatus, an image forming apparatus including the image reading apparatus, and an image reading method executed by the image reading apparatus.

  An image reading apparatus such as a scanner outputs a light source that emits light toward a document placed on a document placement surface, and an analog signal corresponding to the amount of light emitted from the light source and reflected by the document. A photoelectric conversion unit. In this type of image reading apparatus, an analog signal output from the photoelectric conversion unit is input to an analog front end circuit. For example, in an analog front end circuit, an input analog signal is clamped with a line period, and then converted into image data of a digital signal and output.

  By the way, in the image reading device, when an image of a three-dimensional object having a mirror surface such as an embossed credit card is read, light emitted from a light source and regularly reflected by the three-dimensional object is irradiated to the photoelectric conversion unit. May be. In this case, an analog signal with an amplitude exceeding the input range of the analog front end circuit is output from the photoelectric conversion unit, and the offset level in the clamp of the line cycle changes, and the read image data has a streak abnormality along the main scanning direction. An image appears. On the other hand, an image reading apparatus capable of suppressing the appearance of the abnormal image in the read image data by dividing the analog signal output from the photoelectric conversion unit according to a user operation is known as a related technique. (See Patent Document 1).

Japanese Patent Laying-Open No. 2015-65620

  However, in the related technology, it takes time for the user to check whether the document is a three-dimensional object having a mirror surface before reading the image of the document.

  An object of the present invention is to provide an image reading apparatus, an image forming apparatus, and an image reading method capable of suppressing an abnormal image from appearing in read image data and reducing a user's trouble.

  An image reading apparatus according to one aspect of the present invention includes a photoelectric conversion unit, an electric circuit, a first reading processing unit, a first determination processing unit, a second determination processing unit, a partial pressure processing unit, and a correction. A processing unit. The photoelectric conversion unit outputs an analog signal corresponding to the amount of light reflected by the document placed on the document placement surface. The electric circuit includes a clamp unit that clamps the analog signal output from the photoelectric conversion unit at a line period, and a signal conversion unit that converts the analog signal clamped by the clamp unit into image data of a digital signal. . The first reading processing unit executes a first reading process for reading image data of the document. The first determination processing unit determines whether or not the size of the image data of the document read by the first reading process matches a predetermined specific size. The second determination processing unit includes, when the first determination processing unit determines that the size of the image data of the document matches the specific size, whether the image data of the document includes a predetermined specific image Judge whether or not. The voltage dividing processing unit applies a predetermined voltage dividing ratio to the analog signal output from the photoelectric conversion unit when the second determination processing unit determines that the image data of the document includes the specific image. Divide pressure with. When the analog signal output from the photoelectric conversion unit is divided by the voltage dividing processing unit, the correction processing unit determines the pixel density of image data output from the electric circuit according to the voltage dividing ratio. To correct.

  An image forming apparatus according to another aspect of the present invention includes the image reading device and an image forming unit. The image forming unit can form an image based on image data.

  An image reading method according to another aspect of the present invention includes a photoelectric conversion unit that outputs an analog signal corresponding to the amount of light reflected by a document placed on a document placement surface, and an output from the photoelectric conversion unit. And an electric circuit including a clamp unit that clamps the analog signal at a line period and a signal conversion unit that converts the analog signal clamped by the clamp unit into image data of a digital signal. , A reading step, a first determination step, a second determination step, a partial pressure step, and a correction step. In the reading step, a first reading process for reading the image data of the document is executed. In the first determination step, it is determined whether or not the size of the image data of the document read by the first reading process matches a predetermined specific size. In the second determination step, whether or not the image data of the document includes a predetermined specific image when the size of the image data of the document matches the specific size in the first determination step. Is judged. In the voltage dividing step, the analog signal output from the photoelectric conversion unit is divided at a predetermined voltage dividing ratio when it is determined in the second determining step that the image data of the document includes the specific image. Pressed. In the correcting step, when the analog signal output from the photoelectric conversion unit is divided in the voltage dividing step, the pixel density of the image data output from the electric circuit is corrected according to the voltage dividing ratio. Is done.

  According to the present invention, an image reading apparatus, an image forming apparatus, and an image reading method capable of suppressing the appearance of an abnormal image in the read image data and reducing the trouble for the user are realized.

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a system configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing the configuration of the image reading unit in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a configuration of an image reading unit in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a diagram illustrating a configuration of an image reading unit in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a flowchart illustrating an example of a reading control process executed by the image forming apparatus according to the embodiment of the present invention. FIG. 7 is a flowchart illustrating another example of the reading control process 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 for understanding of the present invention. The following embodiment is an example embodying the present invention, and does 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 disclosure will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus 10.

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

  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, an operation display unit 6, And a storage unit 7.

  The image forming unit 3 can form an image by electrophotography based on the image data. Specifically, the image forming unit 3 includes a photosensitive 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 conveyance path, and a plurality of conveyance rollers, and supplies sheets to the image forming unit 3. The image forming unit 3 forms an image based on the image data on the sheet supplied from the paper feeding unit 4. The sheet after image formation 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 ink jet method.

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

  The operation display unit 6 is a display unit such as a liquid crystal display that displays various types of information in response to control instructions from the control unit 5, and an operation key or touch panel that inputs various types of information to the control unit 5 in response to user operations. And so on.

  The storage unit 7 is a non-volatile storage device such as a hard disk drive or a flash memory. Note that the storage unit 7 may be the RAM or the EEPROM of the control unit 5.

  The ADF 1 conveys a document whose image data is read by the image reading unit 2. Specifically, as shown in FIG. 1, the ADF 1 includes a document placement unit 11, a plurality of transport rollers 12, a document guide 13, and a paper discharge unit 14. 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 the document placed on the first contact glass 211 of the document table 21. Here, the ADF 1 is an example of a cover member in the present invention.

  In the ADF 1, each of the transport rollers 12 is driven by a motor (not shown). As a result, the document placed on the document placement unit 11 is transported through the document transport path formed inside the ADF 1. The document conveyed on the document conveyance path is guided onto the second contact glass 212 of the document table 21 by the document guide 13 and then discharged to the sheet discharge unit 14.

[Configuration of Image Reading Unit 2]
Next, the configuration of the image reading unit 2 will be described with reference to FIGS. Here, FIG. 3 is a schematic diagram showing the configuration of the document table 21. FIG. 4 is a schematic diagram showing the rotation shaft 213 of the document table 21. FIG. 5 is a circuit diagram showing the configuration of the voltage dividing circuit 28 and the changeover switch 29.

  The image reading unit 2 can read image data from a document. Specifically, as shown in FIGS. 1 and 5, the image reading unit 2 includes a document table 21, a reading unit 22, a mirror 23, a mirror 24, an optical lens 25, a CCD 26, an AFE (analog front end) circuit 27, A voltage dividing circuit 28 and a changeover switch 29 are provided.

  The document table 21 is provided on the upper surface of the casing of the image forming apparatus 10. As shown in FIGS. 2 to 4, the document table 21 includes a first contact glass 211, a second contact glass 212, a rotation shaft 213, and a closing detection unit 214.

  A document is placed on the first contact glass 211. In the image forming apparatus 10, documents of various sizes are placed on the first contact glass 211 in accordance with the placement reference position P <b> 1 shown in FIG. 3. Here, the first contact glass 211 is an example of a document placement surface in the present invention.

  The second contact glass 212 transmits light emitted from the reading unit 22 toward the document conveyed by the ADF 1. The rotation shaft 213 is provided along the surface of the first contact glass 211. The rotation shaft 213 supports the ADF 1 so as to be rotatable in the rotation direction D1 (see FIGS. 3 and 4).

  The closing detection unit 214 detects the transition of the ADF 1 from the open state to the closed state. For example, the closure detection unit 214 is an optical sensor including a photodiode that outputs an electrical signal corresponding to the amount of received light. For example, when the voltage of the electrical signal output from the photodiode becomes less than a predetermined threshold, the closing detection unit 214 outputs a detection signal indicating the transition of the ADF 1 from the open state to the closed state. To enter. The closing detection unit 214 may be a mechanical switch that switches on and off when the ADF 1 is closed.

  As shown in FIG. 1, the reading unit 22 is provided below the first contact glass 211 and the second contact glass 212. The reading unit 22 is configured to be movable in the sub-scanning direction D3 shown in FIG. 3 by a moving mechanism (not shown) having a driving unit such as a stepping motor. As shown in FIG. 1, the reading unit 22 includes a light source 221 and a mirror 222.

  The light source 221 is a plurality of LEDs arranged along the main scanning direction D2 shown in FIG. The light source 221 emits light for one line in the main scanning direction D <b> 2 toward the first contact glass 211 or the second contact glass 212. 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 document placed on the first contact glass 211 or the document 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 image data is read from a document placed on the first contact glass 211, the reading unit 22 is moved in the sub-scanning direction D3 by the moving mechanism. Thereby, the light emitted from the light source 221 to the original is scanned in the sub-scanning direction D3. In the image reading unit 2, when image data is read from a 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. 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.

  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 it 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 D2. The CCD 26 outputs an analog signal corresponding to the amount of received light. Here, the CCD 26 is an example of a photoelectric conversion unit in the present invention.

  In the image reading unit 2, when image data is read from a document placed on the first contact glass 211, the light emitted from the light source 221 and reflected by the document placed on the first contact glass 211 is mirror 222. Then, the light enters the CCD 26 via the mirror 23, the mirror 24, and the optical lens 25. As a result, an analog signal corresponding to the image of the document placed on the first contact glass 211 is output from the CCD 26. Further, in the image reading unit 2, when image data is read from the document conveyed by the ADF 1, the light emitted from the light source 221 and reflected by the document conveyed by the ADF 1 is mirror 222, mirror 23, mirror 24, and The light enters the CCD 26 via the optical lens 25. As a result, an analog signal corresponding to the image of the document conveyed by the ADF 1 from the CCD 26 is output.

  The analog signal output from the CCD 26 is input to the AFE circuit 27 via the voltage dividing circuit 28 or not depending on the switching state of the changeover switch 29. The analog signal output from the CCD 26 has its DC component removed by the coupling capacitor 270 shown in FIG. 5 before being input to the AFE circuit 27.

  The AFE circuit 27 is an electronic circuit that executes processing based on an analog signal output from the CCD 26. As illustrated in FIG. 5, the AFE circuit 27 includes a clamp unit 271 and a signal conversion unit 272. Here, the AFE circuit 27 is an example of an electric circuit in the present invention.

  The clamp unit 271 is an electronic circuit that clamps an analog signal output from the CCD 26 at a line cycle. The analog signal output from the clamp unit 271 is amplified by an amplifier circuit (not shown) and then input to the signal conversion unit 272. The signal conversion unit 272 is an analog-digital converter that converts the analog signal clamped by the clamp unit 271 into image data of a digital signal. The image data output from the signal conversion unit 272 is input to the control unit 5 after being subjected to predetermined signal processing by a signal processing circuit (not shown).

  The voltage dividing circuit 28 divides the analog signal output from the CCD 26 at a predetermined voltage dividing ratio. As shown in FIG. 5, the voltage dividing circuit 28 includes a first resistor 281 and a second resistor 282.

  One end of the first resistor 281 is connected to the CCD 26 via the second buffer 292 of the changeover switch 29, and the other end is connected to the coupling capacitor 270. The second resistor 282 has one end connected between the first resistor 281 and the coupling capacitor 270 and the other end connected to the ground. In the voltage dividing circuit 28, the analog signal output from the CCD 26 is divided according to the ratio (the voltage dividing ratio) between the resistance value of the first resistor 281 and the resistance value of the second resistor 282. Specifically, the voltage dividing ratio is set based on the voltage of the analog signal output from the CCD 26 and the input range of the AFE circuit 27 when the light regularly reflected by the document is irradiated onto the CCD 26.

  The changeover switch 29 switches the presence / absence of input of the analog signal output from the CCD 26 to the voltage dividing circuit 28. As illustrated in FIG. 5, the changeover switch 29 includes a first buffer 291 and a second buffer 292.

  The first buffer 291 has an input terminal connected to the CCD 26 and an output terminal connected to the coupling capacitor 270. In addition, the first buffer 291 has a control terminal 291A connected to the control unit 5, as shown in FIG. In the first buffer 291, when a high-level control signal is input to the control terminal 291A, an analog signal input from the CCD 26 is output. The second buffer 292 has an input terminal connected to the CCD 26 and an output terminal connected to the first resistor 281 of the voltage dividing circuit 28. Further, the second buffer 292 includes a control terminal 292A connected to the control unit 5, as shown in FIG. The second buffer 292 outputs an analog signal input from the CCD 26 when a low-level control signal is input to the control terminal 292A.

  By the way, in the image forming apparatus 10, when an image of a three-dimensional object having a mirror surface such as an embossed credit card is read, the light emitted from the light source 221 and specularly reflected by the three-dimensional object is irradiated to the CCD 26. May be. In this case, an analog signal having an amplitude exceeding the input range of the AFE circuit 27 is output from the CCD 26, the offset level in the clamp unit 271 is changed, and a streak abnormal image along the main scanning direction D2 appears in the read image data. . On the other hand, an image reading apparatus capable of suppressing the appearance of the abnormal image in the read image data by switching whether or not the analog signal output from the CCD 26 is input to the voltage dividing circuit 28 according to a user operation. Known as related technology.

  However, in the related technology, it takes time for the user to check whether the document is a three-dimensional object having a mirror surface before reading the image of the document. On the other hand, in the image forming apparatus 10 according to the embodiment of the present invention, as described below, it is possible to suppress the appearance of the abnormal image in the read image data and to reduce the trouble for the user. is there.

  Specifically, the ROM of the control unit 5 stores in advance a reading control program for causing the CPU to execute a reading control process (see a flowchart of FIG. 6) described later. The reading control program is recorded on a computer-readable recording medium such as a CD, a DVD, or a flash memory, and is read from the recording medium and installed in the EEPROM of the control unit 5. Also good.

  Then, as shown in FIG. 2, the control unit 5 includes a first reading processing unit 51, a first determination processing unit 52, a second determination processing unit 53, a partial pressure processing unit 54, a second reading processing unit 55, and A correction processing unit 56 is included. Specifically, the control unit 5 executes the reading control program stored in the ROM using the CPU. Accordingly, the control unit 5 functions as the first reading processing unit 51, the first determination processing unit 52, the second determination processing unit 53, the partial pressure processing unit 54, the second reading processing unit 55, and the correction processing unit 56. . Here, the apparatus including the image reading unit 2 and the control unit 5 is an example of the image reading apparatus according to the present invention. The present invention can be applied to an image reading apparatus or an image forming apparatus such as a scanner apparatus, a facsimile apparatus, and a copier.

  The first reading processing unit 51 executes a first reading process for reading image data of a document placed on the first contact glass 211.

  For example, the first reading processing unit 51 executes the first reading processing when the closing detection unit 214 detects the shift of the ADF 1 to the closed state.

  The first reading processing unit 51 may execute the first reading process in response to a user operation.

  The first determination processing unit 52 determines whether or not the size of the image data of the document read by the first reading process matches a predetermined specific size.

  Specifically, the specific size is a size of a card such as a credit card. The specific size may be arbitrarily set according to a user operation.

  The second determination processing unit 53 determines whether or not the document image data includes a predetermined specific image when the first determination processing unit 52 determines that the size of the document image data matches the specific size. Judging.

  Specifically, the specific image is a mark used for identifying an issuer of a card included in a credit card. For example, in the image forming apparatus 10, a plurality of the specific images are stored in the storage unit 7 in advance. The specific image may be a character image indicating a card issuer or a card background image. The specific image may be registered in the image forming apparatus 10 according to a user operation.

  For example, the second determination processing unit 53 determines that the image data of the document includes the specific image when the matching rate between the image included in the image data of the document and the specific image exceeds a predetermined threshold. For example, the threshold is set for each specific image based on the positional relationship between the specific image and a region having a mirror surface on the card, the size of the specific image, and the like. In the image forming apparatus 10, the threshold value common to a plurality of the specific images may be set.

  The partial pressure processing unit 54 divides the analog signal output from the CCD 26 by the partial pressure ratio when the second determination processing unit 53 determines that the image data of the document includes the specific image.

  Specifically, the partial pressure processing unit 54 operates the changeover switch 29 to divide the analog signal output from the CCD 26. More specifically, the voltage dividing unit 54 inputs an analog signal output from the CCD 26 to the voltage dividing circuit 28 by switching the voltage level of the control signal input to the changeover switch 29 from a high level to a low level. To do.

  The second reading processing unit 55 executes a second reading process for reading image data of a document placed on the first contact glass 211.

  For example, the second reading processing unit 55 performs the second reading processing in response to a user operation after executing the first reading processing according to the detection of the transition from the open state of the ADF 1 to the closed state by the closing detection unit 214. Run.

  When the first reading process is executed in response to a user operation, the second reading processing unit 55 performs the above operation when the analog signal output from the CCD 26 is divided by the voltage dividing processing unit 54. The second reading process may be executed.

  The correction processing unit 56 corrects the pixel density of the image data output from the AFE circuit 27 according to the voltage dividing ratio when the analog signal output from the CCD 26 is divided by the voltage dividing processing unit 54.

  For example, the correction processing unit 56 corrects the pixel density value of the image data output from the AFE circuit 27 by a factor of two when the voltage division ratio is ½.

[Reading control processing]
Hereinafter, an example of the procedure of the reading control process executed by the control unit 5 in the image forming apparatus 10 will be described with reference to FIG. Here, steps S11, S12,... Represent the numbers of processing procedures (steps) executed by the control unit 5.

<Step S11>
First, in step S <b> 11, the control unit 5 determines whether or not the closing detection unit 214 has detected the transition of the ADF 1 from the open state to the closed state.

  Here, if the control part 5 judges that transfer to the closed state of ADF1 was detected (Yes side of S11), it will transfer a process to step S12. Moreover, if the transition to the closed state of ADF1 is not detected (No side of S11), the control part 5 waits for the detection of the transition to the closed state of ADF1 in step S11.

<Step S12>
In step S <b> 12, the control unit 5 executes the first reading process for reading the image data of the document placed on the first contact glass 211. Here, the processing of step S11 and step S12 is an example of the reading step in the present invention, and is executed by the first reading processing unit 51 of the control unit 5.

<Step S13>
In step S13, the control unit 5 determines whether or not the size of the image data of the document read in step S12 matches the specific size. Here, the process of step S <b> 13 is an example of a first determination step in the present invention, and is executed by the first determination processing unit 52 of the control unit 5.

  If the control unit 5 determines that the size of the image data of the document read in step S12 matches the specific size (Yes in S13), the control unit 5 shifts the process to step S14. If the size of the image data of the document read in step S12 does not match the specific size (No side in S13), the control unit 5 shifts the processing to step S131.

<Step S14>
In step S14, the control unit 5 determines whether the image data of the document read in step S12 includes the specific image. Here, the process of step S <b> 14 is an example of a second determination step in the present invention, and is executed by the second determination processing unit 53 of the control unit 5.

  If the control unit 5 determines that the image data of the document read in step S12 includes the specific image (Yes in S14), the control unit 5 shifts the process to step S15. If the image data of the document read in step S12 does not include the specific image (No in S14), the control unit 5 shifts the process to step S131.

<Step S131>
In step S131, the control unit 5 determines whether or not a user operation for instructing reading of image data of a document placed on the first contact glass 211 is performed on the operation display unit 6.

  If the control unit 5 determines that a user operation for instructing reading of the image data has been performed (Yes in S131), the control unit 5 shifts the processing to step S132. If no user operation for instructing reading of image data is performed (No in S131), the control unit 5 waits for a user operation for instructing reading of image data in step S131.

<Step S132>
In step S <b> 132, the control unit 5 executes the second reading process for reading the image data of the document placed on the first contact glass 211. Here, the process of step S <b> 132 is executed by the second reading processing unit 55 of the control unit 5.

<Step S15>
In step S <b> 15, the control unit 5 divides the analog signal output from the CCD 26 at the voltage dividing ratio. Here, the process of step S15 is an example of a voltage dividing step in the present invention, and is executed by the voltage dividing processing unit 54 of the control unit 5.

  Specifically, the control unit 5 operates the changeover switch 29 to divide the analog signal output from the CCD 26. More specifically, the control unit 5 inputs the analog signal output from the CCD 26 to the voltage dividing circuit 28 by switching the voltage level of the control signal input to the changeover switch 29 from the high level to the low level.

<Step S16>
In step S <b> 16, the control unit 5 determines whether or not a user operation for instructing reading of image data of the document placed on the first contact glass 211 is performed on the operation display unit 6.

  If the control unit 5 determines that a user operation for instructing reading of image data has been performed (Yes in S16), the control unit 5 shifts the process to step S17. If no user operation for instructing reading of image data is performed (No in S16), the control unit 5 waits for a user operation for instructing reading of image data in step S16.

<Step S17>
In step S <b> 17, the control unit 5 executes the second reading process for reading the image data of the document placed on the first contact glass 211. Here, the process of step S <b> 17 is executed by the second reading processing unit 55 of the control unit 5.

<Step S18>
In step S18, the control unit 5 corrects the pixel density of the image data read in step S17 according to the voltage division ratio. Here, the process of step S18 is an example of a correction step in the present invention, and is executed by the correction processing unit 56 of the control unit 5.

  For example, the control unit 5 corrects the pixel density value of the image data read in step S17 to be doubled when the voltage division ratio is 1/2. As a result, the analog signal output from the CCD 26 is divided by the voltage dividing ratio, so that it is avoided that the image data read from the document is entirely dark.

<Step S19>
In step S <b> 19, the control unit 5 releases the partial pressure of the analog signal output from the CCD 26. Specifically, the control unit 5 releases the partial pressure of the analog signal output from the CCD 26 by switching the voltage level of the control signal input to the changeover switch 29 from the low level to the high level.

<Step S20>
In step S20, the control unit 5 outputs the image data read in step S132 or step S17. For example, the control unit 5 stores the read image data in the storage unit 7. Note that the control unit 5 may transmit the read image data to an external information processing apparatus designated in advance. Further, the control unit 5 may execute a printing process based on the read image data.

  In the reading control process described above, the first reading process is executed in response to detection of the transition of the ADF 1 from the open state to the closed state. Then, when the size of the image data of the document read by the first reading process matches the specific size, and the image data of the document read by the first reading process includes the specific image, it is output from the CCD 26. The analog signal is divided by the voltage dividing ratio. Therefore, it is not necessary for the user to check whether or not the document is a three-dimensional object having a mirror surface before setting the document reading mode before reading the image of the document. Therefore, in the image forming apparatus 10, it is possible to suppress the abnormal image from appearing in the read image data and to reduce the trouble for the user.

  Next, another example of the reading control process executed by the control unit 5 in the image forming apparatus 10 will be described with reference to FIG.

<Step S31>
First, in step S <b> 31, the control unit 5 determines whether or not a user operation for instructing reading of image data of a document placed on the first contact glass 211 is performed on the operation display unit 6.

  If the control unit 5 determines that a user operation for instructing reading of image data has been performed (Yes in S31), the control unit 5 shifts the processing to step S32. If no user operation for instructing reading of image data is performed (No in S31), the control unit 5 waits for a user operation for instructing reading of image data in step S31.

<Step S32>
In step S32, the control unit 5 performs the first reading process. Here, the processing of step S31 and step S32 is another example of the reading step in the present invention, and is executed by the first reading processing unit 51 of the control unit 5.

<Step S33>
In step S33, the control unit 5 determines whether or not the size of the image data of the document read in step S32 matches the specific size. Here, the process of step S33 is another example of the first determination step in the present invention, and is executed by the first determination processing unit 52 of the control unit 5.

  If the control unit 5 determines that the size of the image data of the document read in step S32 matches the specific size (Yes side of S33), the control unit 5 shifts the process to step S34. If the size of the image data of the document read in step S32 does not match the specific size (No side in S33), the control unit 5 shifts the process to step S331.

<Step S34>
In step S34, the control unit 5 determines whether the image data of the document read in step S32 includes the specific image. Here, the process of step S34 is another example of the second determination step in the present invention, and is executed by the second determination processing unit 53 of the control unit 5.

  If the control unit 5 determines that the image data of the document read in step S32 includes the specific image (Yes in S34), the control unit 5 shifts the process to step S35. If the image data of the document read in step S32 does not include the specific image (No in S34), the control unit 5 moves the process to step S331.

<Step S331>
In step S331, the control unit 5 outputs the image data read in step S32.

<Step S35>
In step S <b> 35, the controller 5 divides the analog signal output from the CCD 26 with the voltage dividing ratio. Here, the process of step S35 is another example of the voltage dividing step in the present invention, and is executed by the voltage dividing processing unit 54 of the control unit 5.

<Step S36>
In step S36, the control unit 5 executes the second reading process. Here, the process of step S <b> 36 is executed by the second reading processing unit 55 of the control unit 5.

<Step S37>
In step S37, the control unit 5 corrects the pixel density of the image data read in step S36 according to the voltage division ratio. Here, the process of step S37 is another example of the correction step in the present invention, and is executed by the correction processing unit 56 of the control unit 5.

<Step S38>
In step S <b> 38, the control unit 5 releases the partial pressure of the analog signal output from the CCD 26.

<Step S39>
In step S39, the control unit 5 outputs the image data read in step S36.

  In the reading control process described above, the first reading process is executed in response to a user operation. Then, when the size of the image data of the document read by the first reading process matches the specific size, and the image data of the document read by the first reading process includes the specific image, it is output from the CCD 26. The analog signal is divided at the voltage dividing ratio, and the second reading process is automatically executed. Therefore, it is not necessary for the user to check whether or not the document is a three-dimensional object having a mirror surface before setting the document reading mode before reading the image of the document. Therefore, in the image forming apparatus 10, it is possible to suppress the abnormal image from appearing in the read image data and to reduce the trouble for the user.

1 ADF
2 Image reading unit 3 Image forming unit 4 Paper feeding unit 5 Control unit 6 Operation display unit 7 Storage unit 10 Image forming apparatus 21 Document table 22 Reading unit 23, 24 Mirror 25 Optical lens 26 CCD
27 AFE circuit 28 Voltage dividing circuit 29 Changeover switch 51 First reading processing unit 52 First determination processing unit 53 Second determination processing unit 54 Partial pressure processing unit 55 Second reading processing unit 56 Correction processing unit

Claims (7)

A photoelectric conversion unit that outputs an analog signal corresponding to the amount of light reflected by the document placed on the document placement surface;
An electric circuit including a clamp unit that clamps the analog signal output from the photoelectric conversion unit at a line period, and a signal conversion unit that converts the analog signal clamped by the clamp unit into image data of a digital signal;
A first reading processing unit for executing a first reading process for reading image data of the original;
A first determination processing unit configured to determine whether or not a size of image data of the original read by the first reading process matches a predetermined specific size;
A second determination for determining whether or not the image data of the document includes a predetermined specific image when the first determination processing unit determines that the size of the image data of the document matches the specific size. A processing unit;
A voltage division processing unit that divides the analog signal output from the photoelectric conversion unit at a predetermined voltage division ratio when it is determined by the second determination processing unit that the image data of the document includes the specific image. When,
When the analog signal output from the photoelectric conversion unit is divided by the voltage division processing unit, the correction processing unit corrects the pixel density of the image data output from the electric circuit according to the voltage division ratio. When,
An image reading apparatus comprising: A cover member provided to be openable and closable with respect to the document placement surface;
A closure detecting unit for detecting a transition from the open state to the closed state of the cover member,
The first reading processing unit executes the first reading processing when the closing detection unit detects a shift of the cover member to the closed state.
The image reading apparatus according to claim 1. The first reading processing unit executes the first reading processing in response to a user operation,
The image reading device includes:
A second reading processing unit that executes a second reading process of reading image data of the original when the analog signal is divided by the voltage dividing processing unit;
The image reading apparatus according to claim 1. The second determination processing unit determines that the image data of the document includes the specific image when the coincidence ratio between the image included in the image data of the document and the specific image exceeds a predetermined threshold.
The image reading apparatus according to claim 1. A voltage dividing circuit that divides the analog signal output from the photoelectric conversion unit by the voltage dividing ratio;
A switch for switching presence / absence of input of the analog signal output from the photoelectric conversion unit to the voltage dividing circuit,
The partial pressure processing unit operates the changeover switch to divide the analog signal.
The image reading apparatus according to claim 1. An image reading apparatus according to any one of claims 1 to 5, an image forming unit capable of forming an image based on image data,
An image forming apparatus comprising: A photoelectric conversion unit that outputs an analog signal corresponding to the amount of light reflected by the document placed on the document placement surface; a clamp unit that clamps the analog signal output from the photoelectric conversion unit at a line period; And an electric circuit including a signal conversion unit that converts the analog signal clamped by the clamp unit into image data of a digital signal, and an image reading method executed by an image reading apparatus,
A reading step for executing a first reading process for reading image data of the original;
A first determination step of determining whether or not the size of the image data of the original read by the first reading process matches a predetermined specific size;
A second determination step of determining whether or not the image data of the document includes a predetermined specific image when it is determined in the first determination step that the size of the image data of the document matches the specific size; When,
A voltage dividing step of dividing the analog signal output from the photoelectric conversion unit at a predetermined voltage dividing ratio when it is determined in the second determining step that the image data of the document includes the specific image;
When the analog signal output from the photoelectric conversion unit is divided by the voltage dividing step, a correction step of correcting the pixel density of the image data output from the electric circuit according to the voltage dividing ratio;
An image reading method including:

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