JP2016039509A - Image forming apparatus and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can adjust positional shift of respective image data obtained by reading the front face and rear face of a script.SOLUTION: An image forming apparatus includes a first reading part that reads a first face of a script and a second reading part that reads a second face of the script in reading the script, and adjusts at least one of the first reading part and second reading part before reading a script. The image forming apparatus adjusts at least one of the first reading part and second reading part so that image data of the first face created by reading by the first reading part and image data of the second face created by reading by the second reading part match with a block area that is a reference unit in compressing the image data.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an image forming apparatus and a control method capable of reading a front surface and a back surface of a document by a single reading operation.

  2. Description of the Related Art Conventionally, there has been known an image reading apparatus including two image reading units for reading a front surface and a back surface of one original document fed from an automatic document feeder by one reading operation. Image data generated by reading the front and back surfaces is sent to an external host computer or an image forming unit that forms an image on a recording medium such as printing paper. Patent Document 1 describes that image data corresponding to each of the front and back surfaces is stored in one buffer in the image reading apparatus, and the encoded data in the image reading apparatus is generated as a front and back integrated data. Yes. The image reading apparatus transmits the encoded data to the information processing apparatus, and the information processing apparatus acquires the image data of each of the front surface and the back surface from the received encoded data.

JP 2003-324611 A

  In Patent Document 1, the image data for the front surface and the back surface are stored in one buffer in the image reading apparatus, and encoded data that is integrated with the front and back is generated by one encoding unit in the image reading apparatus. Then, the information processing apparatus decodes and acquires the image data for the front and back surfaces from the received encoded data.

  Here, a slight attachment error may occur at the position of each of the two image reading units in the image reading apparatus. Therefore, when the information processing apparatus separates the front and back document areas from the decoded image data and re-encodes each document area, the boundary position of the first encoded block and the second encoded block The boundary position may be different.

  In an encoding method such as JPEG, data compression is performed in units of rectangular blocks such as 8 × 8 pixels or 16 × 16 pixels. Therefore, the continuity of the luminance value and the color value may be lost at the block boundary. If decoding is performed in a state where the continuity is lost and re-encoding is performed at a position where the block boundary is not the block boundary at the time of encoding, the image area where the continuity is lost is included in the block, and the compression efficiency Will fall. However, Patent Document 1 does not consider a case where image data does not coincide with the boundary position of the encoded block due to an attachment error or the like.

  An object of the present invention is to solve such conventional problems. An object of the present invention is to provide an image forming apparatus and a control method capable of adjusting a positional deviation of a document area of each image data obtained by reading the front and back surfaces of a document.

  In order to solve the above problems, an image forming apparatus according to the present invention includes a first reading unit that reads a first surface of a document and a second reading unit that reads a second surface of the document when the document is read. And a control unit that adjusts at least one reading position of the first reading unit and the second reading unit before reading the document, and the control unit is configured by the first reading unit. The block area that serves as a reference unit when the image data of the first surface read and generated and the image data of the second surface read and generated by the second reading unit are compressed It is characterized in that at least one reading position of the first reading means and the second reading means is adjusted so as to match.

  According to the present invention, according to the present invention, it is possible to adjust the positional deviation of the document area of each image data obtained by reading the front and back surfaces of the document.

1 is a block diagram illustrating a configuration of a multifunction machine. 2 is a diagram illustrating a configuration of an automatic document feeder. FIG. It is a figure which shows the encoding data read by double-sided reading. It is a figure which shows the shift | offset | difference of an image start position. It is a figure explaining the operation | movement by the adjustment value for adjusting an image start position. It is a figure explaining the control by the adjustment value in the case of single-sided reading. It is a figure explaining the control by the 1st surface adjustment value in the case of double-sided reading. It is a figure explaining the control by the 2nd surface adjustment value in the case of double-sided reading. It is a flowchart which shows the reading control process by an adjustment value. It is a flowchart which shows a reading process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the present invention. . The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

[First Embodiment]
FIG. 1 is a block diagram illustrating a configuration of the image reading apparatus. In the present embodiment, for example, a multifunction peripheral (MFP) in which a plurality of functions such as a copy function, a scan function, a printer function, and a facsimile function are integrated is used as the image reading apparatus. The multi-function device 1 is connected to an external computer 3 through an external interface 4 and an external bus 2 so as to communicate with each other. The external bus 2 is configured by a USB (Universal Serial Bus), but may be a network connection that can be connected to a plurality of external devices or another interface.

  The CPU 11 is a processor that comprehensively controls the multifunction device 1. The internal bus 15 is a bus that connects the blocks to each other. The ROM 12 is for storing programs that run on the CPU 11 and various data. The RAM 13 is a rewritable working memory in which stored data is volatilized when the power is turned off, and is also used as a working memory for the CPU 11. On the other hand, the nonvolatile RAM 14 is a rewritable memory that does not volatilize content data even when the power is turned off. For example, the CPU 11 implements the operation of the present embodiment by reading the program stored in the ROM 12 into the RAM 13 and executing it. The operation unit 5 accepts various operation instructions from an operator (user), and displays various states of the multifunction machine 1 such as a power supply state, the status of each job, and the like to the user.

  In the multi function device 1, the first side image reading unit 7 and the second side image reading unit 8 are image sensor units that optically read the first side (front side) and the second side (back side) of the document, respectively. The image sensor unit includes a light source that irradiates light on a document and an image sensor in which elements that read reflected light from the document and perform photoelectric conversion are arranged.

  The multi-function device 1 can read both sides of a double-sided document substantially simultaneously (by one paper conveyance) by two image reading units. The first side of the single-sided original and the double-sided original is read by the first side image reading unit 7, and the second side of the double-sided original is read by the second side image reading unit 8. As described above, the reading time of the double-sided original can be shortened by reading both sides of the double-sided original almost simultaneously (by one paper conveyance).

  The image reading control unit 6 performs A / D (analog / digital) conversion on the analog signals of the first surface image reading unit 7 and the second surface image reading unit 8, or the first surface image reading unit 7 and the second surface image. Characteristic correction such as gain adjustment of the reading unit 8 is performed. Further, the image reading control unit 6 has a circuit for performing DMA (direct memory access) transfer in order to store the digital image data in the RAM 13.

  The multifunction device 1 reads a double-sided document using the first side image reading unit 7 and the second side image reading unit 8 and processes analog signals output from the two image reading units by one image reading control unit 6. To do. When reading a double-sided document, the image reading control unit 6 sequentially processes the analog signals output from the two image reading units in the order of the first side and the second side to form one digital image data, and stores it in the RAM 13. Therefore, the read image data includes image data of the first surface and image data of the second surface in one image data as shown in FIG. 3 described later. In this way, by processing the signals from the two image reading units by one image reading control unit, the circuit scale can be reduced and the cost can be reduced as compared with the case where two image reading control units are provided. Can do.

  The image processing unit 9 is a circuit that reads out image data stored in the RAM 13 and performs various image processing and image conversion processing for image formation. The image processing unit 9 includes a circuit that reads out image data stored in the RAM 13 and performs an encoding process using JPEG or the like, and a circuit that decodes the encoded data (encoded data). Here, JPEG is described as an example of the encoding method, but the present invention is not limited to JPEG encoding, and other encoding methods may be used.

[Scan Function]
When reading a double-sided document, the image reading control unit 6 encodes the image data stored in the RAM 13 by JPEG or the like in the image processing unit 9 and stores the encoded data in the RAM 13 again. The encoding process by the image processing unit 9 is performed in parallel with the process of storing the image data of the image reading control unit 6 in the RAM 13. Further, the image reading control unit 6 releases the area of the RAM 13 in which the image data on which the encoding process has been performed is stored, and the area is used by the image reading control unit 6 to store the image data again. In this way, by sequentially encoding the read image data, it is possible to store a larger amount of image data on the RAM 13 as compared with the case of not encoding. As a result, efficient reading can be realized even when the usable storage area is limited. In addition, when the image data is transmitted to the external computer 3, the amount of communication data is smaller than when the image data is not encoded, so that the speed can be increased.

  When the multifunction device 1 is used as a scanner, when the single-sided document is read using the automatic document feeder, the first-side image reading unit 7 first loads the document loaded on the document stacking unit described later. The analog signal is output by reading the surface. Then, the image reading control unit 6 performs A / D conversion and characteristic correction, and stores them in the RAM 13 as image data. The image processing unit 9 JPEG encodes the image data stored in the RAM 13 and stores the encoded data in the RAM 13. The image processing unit 9 transmits the encoded data to the computer 3 via the external interface 4 and the external bus 2.

  On the other hand, when reading a double-sided document using an automatic document feeder, first, the first side image reading unit 7 and the second side image reading unit 8 are stacked on a document stacking unit described later. It reads the front and back sides of the document almost simultaneously and outputs an analog signal. The image reading control unit 6 performs A / D conversion and characteristic correction, and stores image data in which the image data of the first side and the second side of the double-sided document are integrated in the RAM 13. The image processing unit 9 JPEG encodes the image data stored in the RAM 13 and stores the encoded data in the RAM 13. The image processing unit 9 transmits the encoded data to the computer 3 via the external interface 4 and the external bus 2.

  When the computer 3 receives the encoded data in which the first side and the second side of the double-sided document are integrated, the computer 3 decodes and cuts out the document area of each side and creates image data corresponding to each side. The image data is re-encoded by JPEG or the like and stored in the storage area of the computer 3.

  Here, the operation of transmitting the encoded data in which the first side and the second side of the double-sided document are integrated to the computer 3 has been described. However, the first side and the second side are cut out by decoding by the multifunction machine 1. Thereafter, the respective image data may be transmitted to the computer 3. In that case, the image processing unit 9 re-encodes the encoded data in which the first side and the second side of the double-sided document stored in the RAM 13 are integrated while decoding the document area on the first side, The encoded data of the first surface is stored in the RAM 13. Next, the image processing unit 9 re-encodes the original area of the second side while decoding, and stores the encoded data of the second side in the RAM 13. The image processing unit 9 transmits the first plane encoded data and the second plane encoded data stored in the RAM 13 to the computer 3 via the external interface 4 and the external bus 2. Although the operation of storing encoded data once in the RAM 13 and transmitting it to the computer 3 has been described here, re-encoding and transmission may be performed in parallel.

[Copy function]
When the multifunction machine 1 is used as a copying machine to execute a single-sided document copy function, the operation until the encoded data is stored in the RAM 13 is the same as that for scanning a single-sided document. The image processing unit 9 decodes the encoded data, performs various image processing on the image data, and outputs the image data to the image forming unit 10. The image forming unit 10 forms an image on a recording medium based on the image data that has been subjected to image processing.

  Even when the copy function of the double-sided original is executed, the operation until the encoded data is stored in the RAM 13 is the same as the scanning of the double-sided original. The image processing unit 9 decodes the image data corresponding to the first surface from the encoded data, performs various image processing on the image data, and outputs the image data to the image forming unit 10. The image forming unit 10 forms an image on a recording medium based on image data corresponding to the first surface on which image processing has been performed. Next, the image processing unit 9 decodes the image data corresponding to the second surface from the encoded data, performs various image processing on the image data, and outputs the image data to the image forming unit 10. The image forming unit 10 forms an image on a recording medium based on the image data of the second surface on which image processing has been performed.

[Facsimile transmission function]
When a single-sided original is transmitted using the multifunction device 1 as a facsimile on the reading side, the operation until the image data is stored in the RAM 13 is the same as that for scanning a single-sided original. The image processing unit 9 encodes the image data in the RAM 13 using JPEG or the like, and stores it again in the RAM 13 as code data. Next, the CPU 11 writes the code data read from the RAM 13 to the modem 16, modulates the code data, and transmits the code data to an external facsimile machine via the public line 17 based on the communication function defined by the CCITT recommendation.

  When a double-sided document is transmitted, the operation until the encoded data is stored in the RAM 13 is the same as the scanning of the double-sided document. The image processing device 9 decodes the image data corresponding to the first surface from the encoded data, re-encodes the image data using JPEG or the like, and stores it again in the RAM 13 as the code data of the first surface. Then, the code data of the first side is transmitted to an external facsimile machine as in the case of a single-sided original. Next, the image processing device 9 decodes the image data corresponding to the second surface from the encoded data, encodes it by JPEG or the like, and stores it again in the RAM 13 as the code data of the second surface. Then, after the transmission of the code data on the first surface is completed, the code data on the second surface is transmitted to an external facsimile machine.

  FIG. 2 is a configuration diagram for explaining the operation of the automatic document feeder of the multifunction machine 1. FIG. 2 is a schematic cross-sectional view of a document transport path (transport path) of the automatic document feeder. In the automatic document feeder, the document stacking unit 201 is a stacking tray for stacking documents. When reading using the automatic document feeder, first, the uppermost document 202 of the document stacking unit 201 is fed into the automatic document feeder by the paper feed roller 203. The document 202 is conveyed by the conveyance roller 204 along the conveyance path, and reading is started when the leading edge of the document reaches the first surface reading position 214. After the start of reading, reading is performed along with the conveyance of the original 202 (so-called flow reading), and reading is performed up to the rear end of the original or after reading a predetermined number of originals, the reading ends.

  The document 202 after reading is discharged to a document discharge unit 206 by a discharge roller 205. Here, a configuration has been described in which reading is started from the leading edge of the document and reading is performed up to the end of the document, but reading is started first by a predetermined amount from the leading edge of the document, or is determined in advance from the trailing edge of the document. Alternatively, the reading may be terminated later by a predetermined amount.

  The first side image reading unit 209 is an image sensor unit for reading the first side of the document, and corresponds to the first side image reading unit 7 of FIG. The first surface of the document corresponds to the upward surface of the document 202 stacked on the document stacking unit 201. The first surface image reading unit 209 is movable in the direction of the arrow 211 in the drawing, and is located at the standby position 212 except during the reading operation. In the case of reading using the automatic document feeder, the first surface image reading unit 209 stops at the first surface reading position 214 and reads the first surface of the document conveyed along the conveyance path.

  The second side image reading unit 210 is an image sensor unit for reading the second side of the document, and corresponds to the second side image reading unit 8 of FIG. The second surface image reading unit 210 is fixed at the second surface reading position 217 of the automatic document feeder, and reads the second surface of the document conveyed along the conveyance path. The second surface of the document corresponds to the downward surface of the document 202 stacked on the document stacking unit 201.

  Since the first-side image reading unit 209 and the second-side image reading unit 210 are separated by a distance 218 between the reading units, when performing simultaneous double-sided reading, the first-side original image position and the second side in the read image The document image position is separated by a reading unit distance 218. The image data read by the simultaneous duplex reading will be described later with reference to FIG. Here, the configuration in which the second side image reading unit 210 is fixed to the automatic document feeder has been described, but the configuration in which the second side image reading unit 210 is movable and the second side reading position 217 is adjusted. It is also good. Note that the simultaneous double-sided reading refers to processing for reading images on the front and back surfaces by one sheet conveyance using two image reading units.

  The document sensor 207 is a sensor for detecting the presence or absence of a document on the document stacking unit 201. The document front end sensor 208 is a sensor for detecting the front end position of the document transported by the transport roller 204. When the leading edge of the document 202 conveyed by the conveying roller 204 reaches the document leading edge sensor 208, the value of the sensor changes, whereby it is detected that the leading edge of the document 202 is at the position 215 of the document leading edge sensor 208. Further, the document leading edge sensor 208 has a sensor value that changes when the trailing edge of the document 202 passes the document leading edge sensor 208, so that the position of the trailing edge of the document 202 is at the position 215 of the document leading edge sensor 208. Detected.

  Based on the detected leading edge position and trailing edge position of the document, reading start and reading end are performed. The reading start timing of the document 202 is after the document is transported by a predetermined transport amount (reading start transport amount) from the time when the document leading edge sensor 208 detects the leading edge position of the document (timing when the document is transported). The The reading end timing of the document 202 is after the document is transported by a predetermined transport amount (reading transport amount) from the time when the document leading end sensor 208 detects the trailing end position of the document (timing when the document is transported). Is done. The document leading edge sensor 208 serves as a reference position on the conveyance path for determining the timing of reading start and reading end. The reading start conveyance amount and the reading end conveyance amount will be described later with reference to FIGS.

  The first-side image reading unit 209 is used not only for reading using an automatic document feeder but also for reading a fixed document. In the original fixed reading, the first side image reading unit 209 reads the original placed on the fixed original reading surface 213 while moving in the direction of the fixed original reading surface 213.

  FIG. 3 is a diagram illustrating image data 301 after JPEG encoding read by simultaneous double-sided reading. As described with reference to FIG. 1, in the multifunction device 1, two image reading units are controlled by one image reading control unit, and image data in which the first surface 305 and the second surface 306 are integrated is generated. The An arrow 302 in the drawing indicates the main scanning direction X of the first surface image reading unit 209. Here, the main scanning direction X is the arrangement direction of the imaging elements of the image sensor of the image reading unit. An arrow 303 in the figure indicates the sub-scanning direction Y. A sub-scanning direction Y indicates a conveyance direction in which an original is conveyed by the automatic document feeder.

  A start position X307 and a start position Y309 indicate the image start position of the first surface 305 of the document in the image data 301. The width X308 indicates the reading width of the first surface 305, and the height Y310 indicates the reading height of the first surface. A start position X 311 and a start position Y 313 indicate the image start position of the second surface 306 of the document in the image data 301. A width X312 indicates the reading width of the second surface 306, and a height Y314 indicates the reading height of the second surface.

  Usually, the image start position on the first surface 305 and the image start position on the second surface are set so as to coincide (match) with the boundary of the block region 304 which is a reference unit for JPEG encoding. However, a slight attachment error may occur at the position of each of the two image reading units in the image reading apparatus. Therefore, when the information processing apparatus separates the front and back document areas from the decoded image data and re-encodes each document area, the boundary position of the encoding block in the image forming apparatus and the information processing apparatus There are cases where the boundary position of the encoded block differs.

  In an encoding method such as JPEG, the data compression is performed in units of rectangular blocks such as 8 × 8 pixels or 16 × 16 pixels, so that the continuity of luminance values and color values in the block boundary may be lost. . If decoding is performed in a state where the continuity is lost and re-encoding is performed at a position where the block boundary is not the block boundary at the time of encoding, the image area where the continuity is lost is included in the block, and the compression efficiency Will fall.

  In FIG. 3, the image on the second surface 306 is shifted backward by the shift amount 315 in the sub-scanning direction from the image on the first surface 305. This is because the image sensor units of the first surface image reading unit 209 and the second surface image reading unit 210 are shifted in position so as not to interfere with each other, as shown in FIG. In the present embodiment, the case where the second surface 306 is displaced backward is shown, but the present invention is not limited to this, and the first surface 305 may be displaced backward, or the first surface. The case where 305 and the 2nd surface 306 are not mutually shifted | deviated may be sufficient.

  FIG. 4 is a diagram illustrating a case where there is a deviation of the image start position between the first surface 305 and the second surface 306 in the image data read by the simultaneous duplex reading. As shown in FIG. 3, in general, the image start position of the document area is overlapped with the boundary of the JPEG encoded block in order to suppress image deterioration when the encoded data is decoded and re-encoded. Thus, there is no misalignment of blocks during re-encoding.

  However, the image start position of the first surface 305 in the image data 301 may be shifted due to the shift of the stop position of the first surface image reading unit 209. In addition, there is a case where the image start position of the second surface 306 in the image data is shifted due to the displacement of the mounting position of the second surface image reading unit 210. Even when there is no positional deviation of the image reading unit, the image start position of the first surface 305 or the image start position of the second surface 306 in the image data 301 is also affected by the deflection or tension of the document passing through the conveyance path. Deviation may occur.

  FIG. 4A shows a state in which the image start position of the first surface 305 is shifted by a shift amount 401 in the sub-scanning direction with respect to the boundary of the JPEG encoded block. FIG. 4B shows a state where the image start position of the second surface 306 is shifted by a shift amount 402 in the sub-scanning direction with respect to the boundary of the JPEG encoded block.

  As shown in FIGS. 4A and 4B, when the image areas of the first surface 305 and the second surface 306 whose image start positions are shifted are re-encoded after decoding, JPEG encoding at the time of encoding is performed. Re-encoding is performed with a shift amount 401 and a shift amount 402 shifted from the block boundary. Therefore, image degradation due to re-encoding occurs.

  Hereinafter, a configuration for adjusting the deviation from the boundary of the JPEG encoded block in the sub-scanning direction of the image start position will be described.

  FIG. 5 is a diagram illustrating an operation for adjusting the image start position. As shown in FIG. 4, when the image start position is deviated from the boundary of the JPEG encoded block, a deviation from the block at the time of re-encoding occurs. Therefore, the multifunction device 1 performs a position adjustment operation for setting the image start position as the boundary position of the JPEG encoded block after reading. The position adjustment operation is performed based on an adjustment value stored in advance in the nonvolatile RAM 14 of the multifunction machine 1. There are two adjustment values, a first surface adjustment value 503 for adjusting the image start position of the first surface 305 and a second surface adjustment value 504 for adjusting the image start position of the second surface 306.

  The first surface adjustment value 503 and the second surface adjustment value 504 are integer values in units of reading resolution for reading using, for example, an automatic document feeder, which are stored in advance in the nonvolatile RAM 14 of the multifunction machine 1. In addition to the reading resolution unit, a numerical value in a physical unit may be used as the adjustment value.

  The first surface adjustment value 503 and the second surface adjustment value 504 may be configured to be received on a user interface displayed on the operation unit 5 of the multifunction machine 1. Alternatively, the first surface adjustment value 503 and the second surface adjustment value 504 may be values received from the external computer 3 via the external interface 4 and stored in the nonvolatile RAM 14. The values of the first surface adjustment value 503 and the second surface adjustment value 504 are acquired, for example, by reading a test document (test reading) from which a deviation amount can be confirmed. That is, the amount of positional deviation of the document area in the test image data is detected, and a value for correcting the detected amount of positional deviation is acquired as an adjustment value.

  Here, although two adjustment values are described for the first surface 305 and the second surface 306, the adjustment value is not particularly limited to two. The adjustment value may be provided with a plurality of adjustment values, such as selection for each function such as copying or faxing, for each reading method such as single-sided reading or simultaneous double-sided reading, and according to the document conveyance speed. Alternatively, the adjustment value may be received from the external computer 3 and set for each reading operation or each read original.

  The sub-scanning position 501 and the sub-scanning position 502 in FIG. 5 respectively indicate the image start position on the first surface 305 and the image start position on the second surface 306 when there is no image position deviation in the document area. FIG. 5A shows an image when the first surface adjustment value 503 and the second surface adjustment value 504 are 0 in a state where the image start position of the first surface 305 and the image start position of the second surface 306 are misaligned. Data is shown. FIG. 5B shows the moving direction of the image data when “+” is set as the first surface adjustment value 503 and the second surface adjustment value 504 from the state of FIG. 5A. When the value “+” is set, the image data is adjusted downward in the sub-scanning direction as indicated by the arrow in FIG.

  An adjustment operation when the first surface adjustment value 503 in FIG. 5B is set to “+” and the image start position of the first surface 305 is moved downward will be described. If reading is started after the leading edge of the sheet has passed the first surface image reading unit 209, adjustment is required to move the image start position of the first surface 305 downward. Here, a case where the first surface adjustment value 503 is +24 lines will be described. For example, it is a case where it is determined from the image data obtained by the above-described test reading that the image start position of the first surface 305 needs to be moved downward by 24 lines. In this case, the reading position of the first surface image reading unit 209 is set to a position shifted from the first surface reading position 214 by 24 lines toward the standby position 212 side. That is, at the start of reading, the first surface image reading unit 209 is controlled to move from the standby position 212 to a position corresponding to the “first surface reading position 214 + 24 line”. In other words, reading was started after the leading edge of the sheet passed over the first-surface image reading unit 209 before adjustment, but reading started when the leading edge of the sheet arrived at the first-surface image reading unit 209 by the adjustment process. Is done. Therefore, the start position of the image on the first surface 305 is matched (aligned) with the boundary of the block area 304 which is a reference unit for JPEG encoding.

  The adjustment operation when the second surface adjustment value 504 in FIG. 5B is set to “+” and the image start position of the second surface 306 is moved downward will be described in detail. Note that, when reading is started after the leading edge of the sheet has passed the second surface image reading unit 210, adjustment is required to move the image start position of the second surface 306 downward. Here, the case where the second surface adjustment value 504 is +24 lines will be described. In this case, the reading position of the first surface image reading unit 209 is set to a position shifted from the first surface reading position 214 by 24 lines on the opposite side to the standby position 212. That is, at the start of reading, the first surface image reading unit 209 is controlled to move from the standby position 212 to a position corresponding to the “first surface reading position 214-24 line”. Next, the reading start conveyance amount after passing through the document leading edge sensor 208 is set shorter by 24 lines. That is, at the start of reading, the reading start conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208−24 lines”, and the timing for starting the document flow reading is advanced by 24 lines. As a result, the image on the first side is read at the timing when the sheet arrives on the first side image reading unit 209 arranged at a position shifted from the first side reading position 214 by 24 lines on the opposite side to the standby position 212. Is started.

  That is, since the second surface image reading unit 210 is fixed, the position of the first surface image reading unit 209 is first changed to the first position in order to widen the relative difference from the image start position of the first surface 305. Control is performed so as to be positioned away from the two-sided image reading unit 210. However, when the reading start timing is not changed just by shifting the position of the first surface image reading unit 209, the reading start timing of the first surface image reading unit 209 is delayed. That is, reading starts after the leading edge of the sheet passes through the first-surface image reading unit 209 for 24 lines. As a result, a region corresponding to 24 lines from the upper end of the image data of the first surface 305 on the image data 301 cannot be read. Therefore, by controlling the start timing of reading of the first surface image reading unit 209 (the above “−24 line”), control is performed so that the image data of the first surface 305 on the image data 301 is appropriately read. To do. By the operation as described above, only the image start position of the second surface 306 can be adjusted downward in the image data 301.

  FIG. 5C shows the moving direction of the image data when a value of “−” is set for the first surface adjustment value 503 and the second surface adjustment value 504 from the state of FIG. When the value of “−” is set, the image data is adjusted upward in the sub-scanning direction as shown by the arrow in FIG.

  An adjustment operation when the first surface adjustment value 503 in FIG. 5C is set to “−” and the image start position of the first surface 305 is moved upward will be described. If reading is started before the leading edge of the paper arrives at the first surface image reading unit 209, adjustment is required to move the image start position of the first surface 305 upward. Here, a case where the first surface adjustment value 503 is set to −24 lines will be described. For example, it is a case where it is determined from the image data obtained by the above-described test reading that the image start position of the first surface 305 needs to be moved upward by 24 lines. In this case, the reading position of the first surface image reading unit 209 is set to a position shifted from the first surface reading position 214 by 24 lines on the opposite side to the standby position 212. That is, at the start of reading, the first surface image reading unit 209 is controlled to move from the standby position 212 to a position corresponding to the “first surface reading position 214-24 line”. In other words, reading was started before the leading edge of the paper arrived at the first surface image reading unit 209 before adjustment, but reading is performed at the timing when the leading edge of the paper arrived at the first surface image reading unit 209 by the above processing. Be started. Therefore, the start position of the image on the first surface 305 is matched (aligned) with the boundary of the block area 304 which is a reference unit for JPEG encoding.

  An adjustment operation when the second surface adjustment value 504 in FIG. 5C is set to “−” and the image start position of the second surface 306 is moved upward will be described. If reading is started before the leading edge of the sheet arrives at the second surface image reading unit 210, adjustment is required to move the image start position of the second surface 306 upward. Here, the case where the second surface adjustment value 504 is set to −24 lines will be described. The reading position of the first surface image reading unit 209 is set to a position shifted from the reading position 214 of the first surface 305 by 24 lines toward the standby position 212 side. That is, at the start of reading, the first surface image reading unit 209 is controlled to move from the standby position 212 to a position corresponding to the “first surface reading position 214 + 24 line”. Next, the reading start conveyance amount after passing through the document leading edge sensor 208 is set longer by 24 lines. That is, at the start of reading, the reading discharge conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208 + 24 lines”, and the timing for starting the document flow reading is delayed by 24 lines. As a result, the reading is started from the timing when the sheet arrives on the first surface image reading unit 209 arranged at a position shifted to the standby position 212 by 24 lines from the first surface reading position 214.

  That is, since the second surface image reading unit 210 is fixed, the position of the first surface image reading unit 209 is first set for the purpose of reducing the relative difference from the image start position of the first surface 305. Control is performed so as to be positioned in a direction approaching the second surface image reading unit 210. However, when the reading start timing is not changed just by shifting the position of the first surface image reading unit 209, the reading start timing of the first surface image reading unit 209 is advanced. That is, the reading starts from the timing 24 lines before the sheet reaches the first side image reading unit 209. As a result, a blank area for 24 lines is added to the upper end of the image data of the first surface 305 on the image data 301. Accordingly, by delaying the reading start timing of the first surface image reading unit 209 (the above “+24 lines”), control is performed so that the image data of the first surface 305 on the image data 301 is appropriately read. . By the operation as described above, only the image start position of the second surface 306 can be adjusted upward in the image data 301.

  When reading is performed by setting both the first surface adjustment value 503 and the second surface adjustment value 504, the adjustment operation is performed by adding the respective adjustment values. For example, the first surface adjustment value 503 is set to −24 lines and the first surface image start position is moved 24 lines upward, and the second surface adjustment value 504 is set to +24 lines and the second surface image start position is set to the downward direction. Next, a case where 24 lines are moved will be described. In this case, at the start of reading, the first surface image reading unit 209 is controlled to move from the standby position 212 to a position corresponding to “(first surface reading position 214-24 line) -24 line”. Next, the reading start conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208−24 lines”, and the timing for starting the flow reading of the document is advanced by 24 lines.

[Control by adjustment value for single-sided scanning]
FIG. 6 is a diagram for explaining control by adjustment values in the case of single-sided reading. A schematic sectional view 601 of the automatic document feeder is a diagram for explaining the document leading edge position 604 and the position of the first surface image reading unit 605 at the start of reading a document conveyed on the conveyance path 603. As described above, the second surface image reading unit 606 is in a fixed position. Coordinates 608 are the coordinates of the schematic cross-sectional view 601, with the transport path upstream side being the coordinate axis 0 and the transport path downstream side being the + side.

  The image data 602 is image data obtained by reading a document, and is image data output when reading is started in the state of the schematic cross-sectional view 601. Further, the image data 602 includes a document area (area of the character image “A”). The coordinates 607 are the coordinates of the document area, the position when the adjustment value is 0 is the coordinate axis 0, the lower side of the document is the + side, and the upper side of the document is the-side.

  FIG. 6A is a diagram for explaining control when the first surface adjustment value 503 is 0 in single-sided reading. When the adjustment value is 0, the document area is not moved in the image data 602. FIG. 6B is a diagram illustrating control when the first surface adjustment value 503 is “+” in single-sided reading. To set the first surface adjustment value 503 to “+” is to move the document area in the image data 602 downward. Therefore, as shown in the schematic cross-sectional view, the reading start timing is advanced by reducing the reading start conveyance amount in accordance with the first surface adjustment value 503. This is equivalent to shifting the first-surface image reading unit 209 to the standby position 212 side described with reference to FIG.

  FIG. 6C is a diagram for explaining control when the first surface adjustment value 503 is “−” in single-sided reading. To set the first surface adjustment value 503 to “−” is to move the document area in the image data 602 upward. Therefore, as shown in the schematic cross-sectional view, the reading start timing is delayed by increasing the reading start conveyance amount according to the first surface adjustment value 503. This is equivalent to shifting the first-surface image reading unit 209 to the opposite side of the standby position 212 described with reference to FIG.

  That is, as shown in FIGS. 6A to 6C, the control by the first surface adjustment value 503 in the case of single-sided reading is performed by setting the reading start conveyance amount as “the conveyance amount after passing the document leading edge sensor 208−first surface adjustment”. The value is set to “503”. Similarly, the reading completion conveyance amount is also “conveyance amount after passing through the document leading edge sensor 208−first surface adjustment value 503”.

  As described above, the image position adjustment in the case of single-sided reading is performed. However, the image position adjustment in the case of double-sided reading to be described later with reference to FIG.

[Control by adjustment value for duplex scanning]
FIG. 7 is a diagram for explaining the control of the first surface adjustment value 503 for duplex reading. The description of each part in FIG. 7 is the same as in FIG. FIG. 7A is a diagram for explaining control when the first surface adjustment value 503 is 0 and the second surface adjustment value 504 is 0 in the case of duplex scanning. When the first surface adjustment value 503 and the second surface adjustment value 504 are 0, the document area in the image data 602 does not move.

  FIG. 7B is a diagram for explaining the control when the first surface adjustment value 503 is “+” and the second surface adjustment value 504 is 0 in the case of duplex scanning. To set the first surface adjustment value 503 to “+” means that only the document area of the first surface 305 in the image data 602 is moved downward. Therefore, as shown in the schematic cross-sectional view, it is equivalent to accelerating the reading start timing of the document area of the first surface 305 shown in FIG. 6B by positioning the first surface image reading unit 605 on the + side. To achieve the right state.

  FIG. 7C is a diagram for explaining the control when the first surface adjustment value 503 is “−” and the second surface adjustment value 504 is 0 in the case of duplex scanning. When the first surface adjustment value 503 is set to “−”, only the document area of the first surface 305 in the image data 602 is moved upward. Therefore, as shown in the schematic cross-sectional view, it is equivalent to delaying the reading start timing of the document area on the first surface 305 shown in FIG. 6C by positioning the first surface image reading unit 605 on the 0 side. To achieve the right state.

  That is, as shown in FIGS. 7A to 7C, the control by the first surface adjustment value 503 in the case of double-sided reading is performed by setting the first surface image reading unit 605 to “first surface reading position 214 + first surface adjustment”. This is done by placing it at the position of “value 503”.

  FIG. 8 is a diagram for explaining control by the second surface adjustment value 504 in the case of duplex scanning. The description of each part in the figure is the same as in FIG. FIG. 8A is a diagram for explaining the control when the first surface adjustment value 503 is 0 and the second surface adjustment value 504 is 0 in the case of duplex scanning. When the first surface adjustment value 503 and the second surface adjustment value 504 are 0, the document area in the image data 602 does not move.

  FIG. 8B is a diagram for explaining control when the first surface adjustment value 503 is 0 and the second surface adjustment value 504 is “+” in duplex scanning. To set the second surface adjustment value 504 to “+” is to move only the document area of the second surface 306 in the image data 602 downward. Therefore, as shown in the schematic cross-sectional view, the read start timing of the first surface 305 and the second surface 306 is advanced by reducing the reading start conveyance amount according to the second surface adjustment value 504. However, as a result, the reading start timing of the first surface 305 that is not subject to adjustment is also advanced. That is, reading starts before the leading edge of the paper arrives at the first surface image reading unit 605. Accordingly, the first surface image reading unit 605 is positioned on the 0 side (− direction) according to the second surface adjustment value 504, so that the first surface 305 arrives at the timing when the leading edge of the sheet arrives at the first surface image reading unit 605. Start reading the original area. As a result, the document area on the first surface 305 is prevented from moving in the image data 602.

  FIG. 8C is a diagram for explaining control when the first surface adjustment value 503 is 0 and the second surface adjustment value 504 is “−” in duplex scanning. When the second surface adjustment value 504 is set to “−”, only the document area of the second surface 306 in the image data 602 is moved upward. Therefore, as shown in the schematic cross-sectional view, the reading start timing of the first surface 305 and the second surface 306 is delayed by increasing the reading start conveyance amount according to the second surface adjustment value 504. However, as a result, the reading start timing of the first surface 305 that is not subject to adjustment is also delayed. That is, the reading starts after the leading edge of the sheet exceeds the first surface image reading unit 605. Accordingly, by positioning the first surface image reading unit 605 on the + side according to the second surface adjustment value 504, the document area of the first surface 305 is reached at the timing when the leading edge of the paper arrives at the first surface image reading unit 605. Start reading. As a result, the document area on the first surface 305 is prevented from moving in the image data 602.

  That is, as shown in FIGS. 8A to 8C, the control by the second surface adjustment value 504 in the case of double-sided reading is performed by setting the position of the first surface image reading unit 605 to “first surface reading position 214 -first”. This is done by setting the “two-side adjustment value 504”. Further, the reading start conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208−second surface adjustment value 504”. Similarly, the conveyance amount at the end of reading is “conveyance amount after passing through the document leading edge sensor 208−second surface adjustment value 504”.

  Further, when the first surface adjustment value 503 and the second surface adjustment value 504 are simultaneously reflected in the duplex reading, the control operations based on the adjustment values described in FIGS. 7 and 8 are combined. That is, the control by the first surface adjustment value 503 and the second surface adjustment value 504 in the case of double-sided scanning is performed by changing the position of the first surface image reading unit 605 to “first surface reading position 214 + first surface adjustment value 503-2. This is done by setting the “surface adjustment value 504”. Further, the reading start conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208−second surface adjustment value 504”. Similarly, the conveyance amount at the end of reading is “conveyance amount after passing through the document leading edge sensor 208−second surface adjustment value 504”.

[Reading control processing]
FIG. 9 is a flowchart showing the reading control process in this embodiment. Note that each process of the flowchart of the present application is realized, for example, by the CPU 11 reading a program stored in the ROM 12 into the RAM 13 and executing it. In step S901, the CPU 11 determines whether the reading method is single-sided reading or simultaneous double-sided reading. The determination in S901 may be performed based on, for example, the reading setting content on the setting screen displayed on the operation unit 5. If it is determined to be single-sided reading, the process proceeds to S902, and if it is determined to be simultaneous double-sided reading, the process proceeds to S905.

  The processing from S902 to S904 is a control process using the first surface adjustment value 503 in the case of single-sided reading. In step S <b> 902, the CPU 11 controls the first surface image reading unit 209 to move to the first surface image reading position 214. As shown in FIG. 6, the image position adjustment in the case of single-sided reading is performed by adjusting the reading start position conveyance amount and the reading end position conveyance amount, and the first surface image reading position 214 is not adjusted.

  In step S903, the CPU 11 sets a reading start conveyance amount in the case of single-sided reading. As described above, in the case of single-sided scanning, the reading start conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208−first surface adjustment value 503”. In step S <b> 904, the CPU 11 sets a reading completion conveyance amount in the case of single-sided reading. In the case of single-sided scanning, the reading completion conveyance amount is set to “one-side original conveyance amount after passing through the document leading edge sensor 208−first surface adjustment value 503”.

  In the above description, the processing for adjusting the image position adjustment for single-sided scanning with the reading start position conveyance amount and the reading end position conveyance amount has been described. However, as described with reference to FIG. 7, the adjustment is performed at the position of the first surface image reading unit 209. You may make it do.

  The processing from S905 to S907 is control processing using the first surface adjustment value 503 and the second surface adjustment value 504 in the case of simultaneous duplex reading. In step S <b> 905, the CPU 11 controls the first surface image reading unit 209 to move to “first surface image reading position 214 + first surface adjustment value 503 −second surface adjustment value 504”.

  In step S <b> 906, the CPU 11 sets the reading start conveyance amount in the case of simultaneous duplex reading. As described above, in the case of simultaneous double-sided reading, the reading start conveyance amount is set to “conveyance amount after passing through the document leading edge sensor 208−second surface adjustment value 504”. In step S <b> 907, the CPU 11 sets the reading end conveyance amount in the case of simultaneous double-sided reading. In the case of simultaneous double-sided reading, the reading completion conveyance amount is set to “the conveyance amount after passing through the document leading edge sensor 208 on both sides−second surface adjustment value 504”.

  As shown in steps S904 and S907, the second-side image reading unit 210 is different from the first-side image reading unit 209 in the difference between the reading end conveyance amount in the case of single-sided reading and the reading end conveyance amount in the case of simultaneous double-sided reading. This is because it is located downstream of the transport path. In other words, since it is necessary to read by the distance between the first-side image reading unit 209 and the second-side image reading unit 210 at the time of simultaneous double-sided reading than at the time of single-sided reading, It is larger by the distance than the conveyance amount after passing through the document leading edge sensor 208 on one side.

  In step S908, the CPU 11 controls each unit to perform a reading operation. Details of the reading operation will be described later with reference to FIG. After the process of S908, the process of FIG.

  The control process using the adjustment values as described above may be performed for each read document. Alternatively, the image reading position, the reading start conveyance amount, and the reading end conveyance amount determined in advance may be stored in the RAM 13 or the like, and the CPU 11 may read the values during the reading operation and perform the above control processing.

  FIG. 10 is a flowchart showing the procedure of the process of S908. In step S <b> 1001, the CPU 11 conveys the document by the reading start conveyance amount set in step S <b> 903 or S <b> 906 after the document passes the document leading edge sensor 208. In step S1002, the CPU 11 starts a document reading process. In the case of single-sided reading, it is a process that is performed when reading of the first surface 305 is started, and is a start process corresponding to the end process of S1006. In step S <b> 1002, the CPU 11 performs settings for the image reading control unit 6 and the image processing unit 9 and controls the first surface image reading unit 7 to perform image reading. In the case of simultaneous double-sided reading, it is a process that is performed at the start of reading of the first surface 305 and the second surface 306 in order to read both sides of a document almost simultaneously with one paper conveyance, and is a start process corresponding to the end process of S1006. In step S <b> 1002, the CPU 11 performs settings for the image reading control unit 6 and the image processing unit 9, and controls the first surface image reading unit 7 and the second surface image reading unit 8 to perform image reading.

  In step S1003, the CPU 11 controls the image reading unit to read one line of the original. In steps S <b> 1002 to S <b> 1006, the CPU 11 performs flow reading while feeding a document from the automatic document feeder. Therefore, the CPU 11 processes S1003 every time the document is conveyed by a distance corresponding to one line.

  In S1004, the CPU 11 determines whether or not the number of lines equal to or greater than the predetermined number of lines has been read. Here, the predetermined number of lines is, for example, the number of lines when the number of reading lines is predetermined for the reading function, or the number of lines corresponding to the maximum document size that can be fed by the automatic document feeder. is there. If it is determined in S1004 that the number of lines equal to or greater than the predetermined number of lines has been read, the process proceeds to S1006. If it is determined that the number of lines equal to or greater than the predetermined number of lines has not been read, the process proceeds to S1005.

  In step S1005, the CPU 11 determines whether or not the document has been read up to the trailing edge of the document. The determination in S1005 is made based on whether or not the document has been conveyed by the reading completion conveyance amount after the trailing edge of the document has passed the document leading edge sensor 208. Here, the reading completion conveyance amount in the case of single-sided reading is “the conveyance amount after passing the one-side original document sensor 208−first surface adjustment value 503” set in S904 of FIG. The reading completion conveyance amount in the case of simultaneous duplex reading is “conveyance amount after passing the document leading edge sensor 208 on both sides + second surface adjustment value 504” set in S907 of FIG.

  If it is determined in step S1005 that the document has been read to the trailing edge, the process advances to step S1006. On the other hand, if it is determined that the document has not been read to the trailing edge, the processing from S1003 is repeated to continue reading.

  In step S <b> 1006, the CPU 11 ends the reading operation of the document currently being read. In the case of single-sided reading, this processing is performed when reading of the first surface 305 is completed, and the CPU 11 ends the image reading control unit 6 and the image processing unit 9. In the case of simultaneous double-sided reading, this processing is performed when reading of the first surface 305 and the second surface 306 is completed, and the CPU 11 ends the image reading control unit 6 and the image processing unit 9.

  In step S <b> 1007, the CPU 11 determines whether there is a subsequent next document. If it is determined that there is a next original, the processing from S1001 is repeated and the reading operation is continued. On the other hand, if it is determined that there is no next original, the processing in FIG. 10 is terminated.

  The determination in S1007 is, for example, that the document leading edge sensor 208 has detected the leading edge of the document after the document trailing edge that has been read up to the processing of S1006 has passed the document leading edge sensor 208, or the document sensor 207 determines that there is a document on the document stacking table. In this case, it is determined that there is a next document.

  As described above, in the present embodiment, it is possible to adjust the sub-scanning position of the document area in the image data on the front and back surfaces in the reading process in which the front and back surfaces can be read in one reading operation. As a result, even when the front and back document areas are decoded from the front and back integrated image data and re-encoded, the deviation of the boundary between the encoded blocks can be reduced.

  The present invention is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  1: MFP, 11: CPU, 12: ROM, 13: RAM, 209: first side image reading unit, 210: second side image reading unit

Claims (9)

A first reading unit that reads a first surface of the document when reading the document; and a second reading unit that reads a second surface of the document;
Control means for adjusting at least one reading position of the first reading means and the second reading means before reading the document;
The control means includes
When the image data of the first surface that is read and generated by the first reading unit and the image data of the second surface that is generated by reading by the second reading unit are compressed. An image forming apparatus comprising: adjusting at least one reading position of the first reading unit and the second reading unit so as to be aligned with a block area serving as a reference unit.   The control unit adjusts the reading position of the first reading unit based on a first adjustment value, and adjusts the reading position of the second reading unit based on a second adjustment value. The image forming apparatus described in 1. Test reading means for reading a first surface of a test document by the first reading means and reading a second surface of the test document by the second reading means;
First acquisition means for acquiring a deviation amount between the test image data of the first surface of the test document read by the test reading means and the block area as the first adjustment value;
Second acquisition means for acquiring a deviation amount between the test image data of the second surface of the test document read by the test reading means and the block area as the second adjustment value;
The image forming apparatus according to claim 2, further comprising:   The image forming apparatus according to claim 2, further comprising a receiving unit configured to receive settings of the first adjustment value and the second adjustment value. A supply unit that supplies a document to a reading position of the first reading unit and a reading position of the second reading unit;
5. The image forming apparatus according to claim 2, wherein the first reading unit and the second reading unit are provided along a conveyance path of the document. 6. When the first reading means is movable and the second reading means is not movable,
The image forming apparatus according to claim 5, wherein the control unit adjusts a reading position of the first reading unit based on the first adjustment value and the second adjustment value. Determining means for determining a reading start timing and a reading end timing of reading the document based on the second adjustment value;
The first reading unit reads the document based on a reading position adjusted by the control unit and the reading start timing and the reading end timing determined by the determination unit. Item 7. The image forming apparatus according to Item 6.   The image forming apparatus according to claim 7, wherein the determining unit determines a conveyance amount of the document from a reference position on the conveyance path for the reading start timing and the reading end timing. A control method executed in an image forming apparatus that includes a first reading unit that reads a first surface of the document and a second reading unit that reads a second surface of the document when reading the document,
A control step of adjusting at least one reading position of the first reading unit and the second reading unit before reading the document;
In the control step,
When the image data of the first surface that is read and generated by the first reading unit and the image data of the second surface that is generated by reading by the second reading unit are compressed. A control method comprising adjusting at least one reading position of the first reading unit and the second reading unit so as to be aligned with a block area serving as a reference unit.

Images