JP6512142B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus.

  Generally, an image reading apparatus for reading an image formed on a document is known. In addition, various techniques for acquiring white reference data and black reference data in an image reading apparatus are known.

  Patent Document 1 describes an image reading apparatus for acquiring white reference data and black reference data. The image reading apparatus includes an image reading unit, a white reference plate, a paper dust removing plate, a white reference data acquisition unit, and a black reference data acquisition unit. The paper dust removing plate has a black surface. The image reading unit generates an original image. The white reference data acquisition unit acquires white reference data, and the black reference data acquisition unit acquires black reference data. Specifically, the image reading unit reads the image of the white reference plate irradiated with light, and the white reference data acquisition unit acquires white reference data based on the read image. Further, the image reading unit reads an image of the black surface irradiated with light, and the black reference data acquisition unit acquires black reference data based on the read image. Therefore, the document image can be subjected to shading correction based on the white reference data and the black reference data. Therefore, the image quality of the document image can be improved.

JP, 2013-110453, A

  However, in the image reading apparatus described in Patent Document 1, since the white reference data and the black reference data are acquired before the document image is read, the document image quality may be degraded. For example, when the document is continuously read, the temperature of the image reading unit rises, and the white reference data and the black reference data change. Therefore, if the document image acquired after the temperature rises is subjected to shading correction with the white reference data and the black reference data acquired before the document image is read, the image quality of the document image may be degraded.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image reading apparatus and an image forming apparatus capable of acquiring white reference data and black reference data at an appropriate timing.

  The image reading apparatus of the present invention includes an image reading unit, a white reference acquisition unit, a black reference acquisition unit, and an acquisition instruction unit. The image reading unit reads an image of a document. The white reference acquisition unit acquires white reference data at document intervals. The black reference acquisition unit acquires black reference data at the document interval. The acquisition instructing unit instructs the white reference acquiring unit to acquire the white reference data based on the document interval. The acquisition instructing unit instructs the black reference acquiring unit to acquire the black reference data based on the document interval. The document interval indicates the interval from when the trailing end of the document in the conveyance direction passes the image reading position to when the leading edge of the succeeding document in the conveyance direction passes the image reading position. The image reading position indicates the position of the document when the image reading unit reads the image of the document.

  An image forming apparatus according to the present invention includes an image forming unit and the image reading apparatus. The image forming unit forms an image on a recording medium.

  According to the image reading apparatus and the image forming apparatus of the present invention, white reference data and black reference data can be acquired at an appropriate timing.

FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of an image reading unit and a document conveyance unit. It is a figure which shows the structure of a control part. It is a flowchart which shows operation | movement of a control part. It is a flowchart which shows the operation | movement in the reference | standard acquisition process of a control part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings (FIGS. 1 to 5). In the drawings, the same or corresponding portions are denoted by the same reference characters and description thereof will not be repeated.

  First, an image forming apparatus 100 according to the present embodiment will be described with reference to FIG. The image forming apparatus 100 is a multifunction peripheral. The image forming apparatus 100 includes an image forming unit 1, an image reading unit 2, and a document conveyance unit 3.

  The image forming unit 1 forms an image on a sheet P which is an example of a recording medium. The image reading unit 2 reads an image formed on the front surface of the front surface and the back surface of the document R. The image reading unit 2 also includes a control unit 5. The document conveyance unit 3 supplies the document R to the image reading unit 2 and reads an image formed on the back surface of the document R. Control unit 5 controls the operation of image forming apparatus 100.

  The image forming unit 1 further includes a sheet feeding cassette 11, a pair of conveyance rollers 12, an image forming unit 13, a fixing device 14, a pair of discharge rollers 15, and a discharge tray 16. The sheet P fed from the sheet feeding cassette 11 is conveyed to the image forming unit 13 by the conveyance roller pair 12.

  The image forming unit 13 forms an image on the sheet P. The sheet P on which the image is formed is conveyed to the fixing device 14. The fixing unit 14 fixes the image formed on the sheet P to the sheet P. The sheet P on which the image is fixed is discharged to the discharge tray 16 by the discharge roller pair 15.

  Next, the image reading unit 2 and the document conveyance unit 3 will be described with reference to FIG. As shown in FIG. 2, the image reading unit 2 includes a contact glass 210, a scanning unit 22, and a rail member 23. The scanning unit 22 includes a first image reading unit 221 and a carriage 222. The first image reading unit 221 is a CIS (Contact Image Sensor) unit that includes an LED (Light Emitting Diode), a contact glass, an imaging lens, and an image sensor, and these components are integrated. The carriage 222 is integrally formed with the first image reading unit 221. The rail member 23 extends in the sub-scanning direction and movably supports the carriage 222. The contact glass 210 includes an original placement glass 212 and an automatic original reading glass 211.

  There are two types of image reading methods of the document R by the image reading unit 2: flat bed reading mode and ADF (Auto Document Feeder) reading mode. In the flatbed reading mode, the image of the document R placed on the document placement glass 212 is read. In the ADF reading mode, the document conveyance unit 3 conveys the document R, and when the document R passes the reading position 211 a, the image on the surface of the document R is read. In the following description, the case where the image reading unit 2 reads an image of the document R placed on the document tray 31 in the ADF reading mode will be described.

  Specifically, in the ADF reading mode, when the document R passes the reading position 211a, the first image reading unit 221 performs continuous reading of the image on the surface of the document R to generate image data.

  The document conveyance unit 3 includes a document tray 31, a pickup roller 32, a paper feed unit 33, a conveyance roller pair 34, a registration roller pair 341, a second image reading unit 351, a white reference roller 352, a conveyance roller pair 35, a reading guide 36, The conveyance roller pair 37, the discharge roller pair 38, and the document discharge tray 39 are provided. Further, the document conveyance unit 3 constitutes an ADF.

  A plurality of documents R (see FIG. 1) are placed on the document tray 31. The pickup roller 32 feeds out the topmost original R of the plurality of originals R toward the sheet feeding unit 33 one by one. The pickup roller 32 starts feeding the next original R after a predetermined inter-paper time TV (original interval) has elapsed since the trailing end of the original R has been fed. The paper feed unit 33 includes a driven roller 331, a drive roller 332, a tension adjustment roller 333, a paper feed belt 334, and a separation roller 335.

  The second image reading unit 351 is a CIS unit that includes an LED, a contact glass, an imaging lens, and an image sensor 351a, and these components are integrated. The second image reading unit 351 reads the image on the back surface of the document R.

  The image reading unit 2 and the document conveyance unit 3 correspond to an "image reading device". The sheet interval time TV corresponds to an example of the "document interval". The inter-sheet time TV indicates the time from when the trailing edge of the document R in the conveyance direction passes the reading position 211a to when the leading edge of the subsequent document R in the conveyance direction passes the reading position 211a. The reading position 211 a corresponds to an example of the “document reading position”.

  Next, the configuration of the control unit 5 according to the present embodiment will be described with reference to FIG. The control unit 5 includes a processor such as a central processing unit (CPU) and a memory such as a semiconductor memory. The control program is stored in the memory. The processor functions as various functional units by executing a control program. As a result, various functional units of the processor control the operation of the image forming apparatus 100. Further, as shown in FIG. 3, the control unit 5 includes a control determination unit 51, a number determination unit 52, a time determination unit 53, an acquisition instruction unit 54, a white reference acquisition unit 55, and a black reference acquisition unit 56.

  The control determination unit 51 determines whether or not correction control is to be performed in the sheet interval time TV. The correction control includes control for changing the conditions under which the image reading unit 2 obtains an image when there is an abnormality including dirt in the image obtained by the image reading unit 2. Specifically, the correction control changes the position (the position in the Y direction in FIG. 2) at which the image reading unit 2 acquires an image when dirt is attached to the automatic document reading glass 211.

  The number determination unit 52 determines whether or not the control determination unit 51 has determined that the correction control is to be performed continuously a predetermined number of times NS. The predetermined number of times NS is, for example, three times.

  The time determination unit 53 determines whether the inter-paper time TV is less than a predetermined time TS. The predetermined time TS indicates a time in which the white reference data DW and the black reference data DK can be acquired. Specifically, the predetermined time TS is the sum of the time required for the white reference acquisition unit 55 to acquire the white reference data DW and the time required for the black reference acquisition unit 56 to acquire the black reference data DK. It is determined in The predetermined time TS is, for example, 500 msec. The time required for the white reference acquisition unit 55 to acquire the white reference data DW is, for example, 250 msec, and the time required for the black reference acquisition unit 56 to acquire the black reference data DK is, for example, 250 msec.

  If the time determining unit 53 determines that the inter-paper time TV is less than the predetermined time TS, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW, or It instructs the black reference acquisition unit 56 to acquire the black reference data DK. Specifically, when the time determination unit 53 determines that the inter-paper time TV is less than the predetermined time TS, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW. An instruction and an instruction to the black reference acquisition unit 56 to acquire the black reference data DK are alternately output.

  In addition, when the time determination unit 53 determines that the inter-paper time TV is not less than the predetermined time TS, the acquisition instructing unit 54 instructs the white reference acquisition unit 55 to acquire the white reference data DW. It instructs the black reference acquisition unit 56 to acquire the black reference data DK.

  The white reference acquisition unit 55 acquires the white reference data DW. Specifically, the white reference acquisition unit 55 acquires the white reference data DW by acquiring light amount data input to the image sensor of the first image reading unit 221 in a state where the LED is turned on. The white reference data DW is used for shading correction of an original image.

  The black reference acquisition unit 56 acquires the black reference data DK. Specifically, the black reference acquisition unit 56 acquires the black reference data DK by acquiring light amount data input to the image sensor of the first image reading unit 221 with the LED turned off. The black reference data DK is used for shading correction of an original image.

  Next, the operation of the control unit 5 will be described with reference to FIG. As shown in FIG. 4, first, in step S101, the document conveyance unit 3 starts sheet feeding. Next, in step S103, the control determination unit 51 determines whether correction control is to be performed in the inter-paper time period TV. If it is determined that correction control is to be performed in the inter-sheet time TV (YES in step S103), the process proceeds to step S109. If it is determined that the correction control is not performed in the inter-sheet time TV (NO in step S103), the process proceeds to step S105. In step S105, a "reference acquisition process" is performed. The “reference acquisition process” is a process in which the white reference acquisition unit 55 acquires the white reference data DW and the black reference acquisition unit 56 acquires the black reference data DK in accordance with an instruction from the acquisition instruction unit 54. When the “reference acquisition process” ends, the process proceeds to step S107. Then, in step S107, the number determination unit 52 initializes the value of the counter N to zero, and the process proceeds to step S111. The counter N counts the number of times the correction control is continuously performed.

  If YES in step S103, the number determination unit 52 increments the value of the counter N by 1 in step S109. Further, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 not to acquire the white reference data DW, and instructs the black reference acquiring unit 56 not to acquire the black reference data DK. Then, the process proceeds to step S111. Next, in step S111, the number determination unit 52 determines whether the value of the counter N is equal to or greater than a predetermined number NS.

  If it is determined that the number of times does not exceed the predetermined number NS (NO in step S111), the process proceeds to step S121. If it is determined that the number of times is the predetermined number NS or more (YES in step S111), the process proceeds to step S113. Then, in step S113, the acquisition instructing unit 54 instructs the document conveyance unit 3 to stop the conveyance of the document R. Then, the document conveyance unit 3 stops the conveyance of the document R. Next, in step S115, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW, and instructs the black reference acquiring unit 56 to acquire the black reference data DK. Then, the white reference acquisition unit 55 acquires the white reference data DW, and the black reference acquisition unit 56 acquires the black reference data DK. Next, in step S117, the document conveyance unit 3 is instructed to start conveyance of the document R. Then, the document conveyance unit 3 starts conveying the document R. Next, in step S119, the number determination unit 52 initializes the value of the counter N to zero, and the process proceeds to step S121.

  If NO in step S111, or if the process of step S119 ends, in step S121, the control unit 5 determines whether to continue the conveyance of the document R. Specifically, when the document R remains in the document tray 31, the control unit 5 determines that the conveyance of the document R is to be continued. On the other hand, when the document R does not remain in the document tray 31, the control unit 5 determines that the conveyance of the document R is not continued. If it is determined that the conveyance of the document R is to be continued (YES in step S121), the process returns to step S103. If it is determined that conveyance of the document R is not continued (NO in step S121), the process ends.

  As described in step S103 and step S109, when the control determination unit 51 determines that the correction control is to be performed, the acquisition instructing unit 54 performs the following process. That is, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 not to acquire the white reference data DW, and instructs the black reference acquiring unit 56 not to acquire the black reference data DK.

  As described in step S111 to step S115, when the control determination unit 51 determines that the correction control is to be performed continuously for a predetermined number of times NS, the acquisition instructing unit 54 performs the following process. That is, the document conveyance unit 3 is instructed to stop the conveyance of the document R, and the white reference acquisition unit 55 is instructed to acquire the white reference data DW, and the black reference acquisition is performed to acquire the black reference data DK. It instructs the part 56.

  Next, the “reference acquisition process” will be described with reference to FIG. The “reference acquisition process” is performed in step S105 of FIG. As shown in FIG. 5, first, in step S201, the time determination unit 53 determines whether the inter-paper time TV is less than a predetermined time TS. If it is determined that the paper interval time TV is less than the predetermined time TS (YES in step S201), the process proceeds to step S207. If it is determined that the paper interval time TV is not less than the predetermined time TS (NO in step S201), the process proceeds to step S203. In step S203, the acquisition instructing unit 54 instructs the black reference acquisition unit 56 to acquire the black reference data DK. Then, the black reference acquisition unit 56 acquires the black reference data DK, and the process proceeds to step S205. Next, in step S205, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW. Then, the white reference acquisition unit 55 acquires the white reference data DW, and the process proceeds to step S111 in FIG. 4.

  In the case of YES in step S201 of FIG. 5, in step S207, the acquisition instructing unit 54 determines whether the read number NR of the document R indicates an odd number. If it is determined that the read sheet number NR indicates an odd number (YES in step S207), the process proceeds to step S211. If it is determined that the read sheet number NR does not indicate an odd number (NO in step S207), the process proceeds to step S209. Then, in step S209, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW. Then, the white reference acquisition unit 55 acquires the white reference data DW, and the process proceeds to step S111 in FIG. 4.

  In the case of YES in step S207 of FIG. 5, in step S211, the acquisition instructing unit 54 instructs the black reference acquisition unit 56 to acquire the black reference data DK. Then, the black reference acquisition unit 56 acquires the black reference data DK, and the process proceeds to step S111 in FIG.

  As described above with reference to FIGS. 1 to 5, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW based on the sheet interval time TV, and the sheet interval time It instructs the black reference acquisition unit 56 to acquire the black reference data DK based on the TV. Therefore, for example, when the sheet interval time TV is long, the white reference data DW and the black reference data DK can be acquired. On the other hand, when the sheet interval time TV is short, the white reference data DW or the black reference data DK can be acquired. Therefore, the white reference data DW and the black reference data DK can be acquired at an appropriate timing.

  The inter-sheet time TV indicates the time from when the trailing edge of the document R in the conveyance direction passes the reading position 211a to when the leading edge of the subsequent document R in the conveyance direction passes the reading position 211a. Therefore, the acquisition instructing unit 54 can accurately determine whether or not both the white reference data DW and the black reference data DK can be acquired.

  Furthermore, when the time determination unit 53 determines that the paper interval time TV is less than the predetermined time TS, the acquisition instructing unit 54 instructs the white reference acquisition unit 55 to acquire the white reference data DW, or Alternatively, it instructs the black reference acquisition unit 56 to acquire the black reference data DK. Thus, the white reference data DW or the black reference data DK can be obtained. On the other hand, when the time determination unit 53 determines that the sheet interval time TV is not less than the predetermined time TS, the white reference acquisition unit 55 is instructed to acquire the white reference data DW, and the black reference data DK is acquired. The black reference acquisition unit 56 is instructed to do this. Therefore, the white reference data DW and the black reference data DK can be acquired. Therefore, the white reference data DW and the black reference data DK can be further acquired at appropriate timing.

  In addition, the predetermined time TS is defined as the sum of the time required for the white reference acquisition unit 55 to acquire the white reference data DW and the time required for the black reference acquisition unit 56 to acquire the black reference data DK. Be Therefore, it can be appropriately determined whether to acquire the white reference data DW or the black reference data DK, or to acquire the white reference data DW and the black reference data DK.

  In addition, when the time determination unit 53 determines that the inter-paper time TV is less than the predetermined time TS, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 to acquire the white reference data DW. An instruction to the black reference acquisition unit 56 to acquire the black reference data DK is alternately output. Therefore, the white reference data DW and the black reference data DK can be alternately acquired. Therefore, the white reference data DW and the black reference data DK can be further acquired at appropriate timing.

  Furthermore, when the control determination unit 51 determines that the correction control is to be performed in the inter-sheet time TV, the acquisition instructing unit 54 instructs the white reference acquiring unit 55 not to acquire the white reference data DW and the black reference It instructs the black reference acquisition unit 56 not to acquire the data DK. When performing correction control in the inter-sheet time TV, the time for acquiring the white reference data DW or the black reference data DK is insufficient. Therefore, the white reference data DW and the black reference data DK can be further acquired at appropriate timing.

  In addition, when the number determination unit 52 determines that the correction control has been determined to be performed a predetermined number of times consecutively, the acquisition instruction unit 54 performs the following process. That is, the acquisition instructing unit 54 instructs the document conveyance unit 3 to stop the conveyance of the document R, instructs the white reference acquisition unit 55 to acquire the white reference data DW, and acquires the black reference data DK. The black reference acquisition unit 56 is instructed to do this. Therefore, the white reference data DW and the black reference data DK can be acquired. Therefore, the white reference data DW and the black reference data DK can be further acquired at appropriate timing. In addition, it is possible to suppress the deterioration of the quality of the document image.

  The embodiments of the present invention have been described above with reference to the drawings. However, this invention is not limited to said embodiment, It is possible to implement in a various aspect in the range which does not deviate from the summary (for example, (1)-(5) shown below). In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, etc. of each component illustrated are different from the actual for convenience of drawing creation. There is a case. The shapes, dimensions, and the like of the components shown in the above-described embodiment are merely examples and are not particularly limited, and various modifications can be made without departing from the configuration of the present invention.

  (1) Although the embodiment has been described in which the "document interval" indicates time with reference to FIG. 2, the present invention is not limited to this. The "document interval" may indicate a distance. Specifically, “document spacing” is the distance from the time when the trailing edge of the document R in the conveyance direction passes the reading position 211 a to the time when the leading edge of the subsequent document R in the direction of conveyance passes the reading position 211 a It may be in the form of indicating the transport distance.

  (2) With reference to FIGS. 3 to 5, the embodiment has been described in which white reference data DW and black reference data DK are alternately acquired when the inter-paper time TV is less than the predetermined time TS. It is not limited to. It may be in any form as long as white reference data DW or black reference data DK is acquired. For example, the white reference data DW may be obtained once every time the black reference data DK is obtained twice.

  (3) Although the embodiment in which the predetermined number of times NS is a fixed number of times (for example, three times) has been described with reference to FIGS. For example, the predetermined number of times NS may be determined based on the resolution of the read image. Specifically, the higher the resolution of the read image, the higher the required image quality, so it is preferable to reduce the predetermined number of times NS.

  (4) Referring to FIG. 3 to FIG. 5, correction control is control for changing the conditions under which the image reading unit 2 obtains an image when there is an abnormality including dirt in the image obtained by the image reading unit 2 Although the form has been described, it is not limited thereto. The correction control may be control performed in the inter-sheet time TV.

  (5) Although the form in which the control unit 5 acquires the white reference data DW and the black reference data DK of the image reading unit 2 has been described with reference to FIGS. 2 to 5, the present invention is not limited thereto. The control unit 5 may acquire white reference data and black reference data of the second image reading unit 351. In this case, the inter-paper time TV is a position where the leading edge of the subsequent document R in the conveyance direction faces the image sensor 351 a from the time when the rear end of the document R in the conveyance direction passes the position facing the image sensor 351a. Indicates the time to the passing point.

  The present invention is applicable to an image reading apparatus and an image forming apparatus.

100 image forming apparatus 1 image forming unit 13 image forming unit 2 image reading unit (part of image reading apparatus)
210 Contact Glass 211a Reading Position (Original Reading Position)
22 scanning unit 221 first image reading unit (image reading unit)
3 Document Transport Unit (Document Transport Unit, Part of Image Reader)
31 document tray 351 second image reading unit 351a image sensor 5 control unit 51 control determination unit 52 number determination unit 53 time determination unit 54 acquisition instruction unit 55 white reference acquisition unit 56 black reference acquisition unit DW white reference data DK black reference data TV Paper interval time (document interval)

Claims (9)

An image reading unit that reads an image of a document;
A document transport unit for transporting the document;
A control determination unit that determines whether or not to perform correction control at document intervals;
A number-of-times determination unit that determines whether the control determination unit continuously determines that the correction control is performed a predetermined number of times;
A white reference acquisition unit for acquiring the white reference data in the document space,
A black reference acquisition unit that acquires black reference data in the document interval;
When the correction control determines that the control determination unit not to perform, and on the basis of the original interval, acquisition instruction unit for performing at least one on for indication of said white reference acquisition unit and the black reference obtaining unit ,
Equipped with
The correction control includes control to change a condition for acquiring the image when the image acquired by the image reading unit is abnormal.
The instruction to the white reference acquiring unit by the acquisition instructing unit indicates acquiring the white reference data;
The instruction to the black reference acquiring unit by the acquisition instructing unit indicates acquiring the black reference data;
The document interval indicates the interval from when the trailing edge of the document in the conveyance direction passes the image reading position to when the leading edge of the subsequent document in the conveyance direction passes the image reading position.
The image reading position, shows the location of the document when the image reading unit reads an image of the document,
When the number determination unit determines that the control determination unit continuously determines the correction control to be performed by the predetermined number of times, the acquisition instructing unit stops the conveyance of the document. To
When the number determination unit determines that the control determination unit continuously determines the correction control to be performed by the predetermined number of times, the acquisition instruction unit includes the white reference acquisition unit and the black reference acquisition unit. Give instructions to at least one of
The instruction to the white reference acquiring unit by the acquisition instructing unit indicates acquiring the white reference data;
The image reading apparatus , wherein the instruction to the black reference acquisition unit by the acquisition instruction unit indicates that the black reference data is acquired .   The system further comprises a counter that counts the number of times the correction control is continuously performed.
  When it is determined that the correction control is to be performed, the value of the counter is incremented by one,
  If it is determined that the correction control is not to be performed, the acquisition instructing unit instructs the at least one of the white reference acquiring unit and the black reference acquiring unit, and the value of the counter is initially set to zero. Are
  When it is determined that the value of the counter is equal to or more than the predetermined number of times, the acquisition instructing unit instructs the at least one of the white reference acquiring unit and the black reference acquiring unit, The image reader according to claim 1, wherein the value is initialized to zero. The document interval indicates a time from when the rear end of the original in the conveyance direction passes the image reading position to when the leading end of the subsequent original in the conveyance direction passes the image reading position. The image reading apparatus according to claim 2 or 3 . The image processing apparatus further comprises a time determination unit that determines whether the document interval is less than a predetermined time.
The acquisition instructing unit
When the time determination unit determines that the document interval is less than the predetermined time, the white reference acquisition unit is instructed to acquire the white reference data, or the black reference data is acquired. Instruct the black reference acquisition unit to
When the time determination unit determines that the document interval is not less than the predetermined time, the white reference acquisition unit is instructed to acquire the white reference data, and the black reference data is acquired. The image reading apparatus according to claim 3 , which instructs the black reference acquisition unit. The predetermined time is defined as a sum of a time required for the white reference acquisition unit to acquire the white reference data and a time required for the black reference acquisition unit to acquire the black reference data. 5. The image reading device according to item 4 .   When the time determination unit determines that the document interval is less than the predetermined time, the acquisition instructing unit acquires the white reference data each time the black reference data is acquired a predetermined number of times. The image reading apparatus according to claim 4, wherein the image reading device is instructed to the white reference acquiring unit and the black reference acquiring unit. If the time determining unit determines that the document interval is less than the predetermined time, the acquisition instructing unit instructs the white reference acquiring unit to acquire the white reference data, and the black reference alternately outputs the instruction to the black reference obtaining unit that that acquires data, the image reading apparatus according to claim 4 or claim 5. When the control determination unit determines that the correction control is to be performed, the acquisition instructing unit instructs the white reference acquiring unit not to acquire the white reference data, and does not acquire the black reference data. To the black standard acquisition unit
Wherein the correction control, when there is an abnormality including dirt image by the image reading unit has acquired, including control for changing the position of the image reading unit acquires an image, any of claims 1 to 7 An image reader according to item 1. An image forming unit that forms an image on a recording medium;
An image forming apparatus comprising the image reading apparatus according to any one of claims 1 to 8 .

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