JP2017011322A - Image reading apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To invalidate white reference data in a case where a piece of paper or the like enters between an image reading part and a shading roller in generation of the white reference data.SOLUTION: An image reading apparatus comprises: a line sensor of a rear side image reading part 40 for reading an image of a document being conveyed; a white shading roller 26 disposed opposite the line sensor; a drive motor which rotates the shading roller 26; document sensors 28 and 29 which detect a piece of paper on the upstream side or downstream side in a document conveyance direction with respect to the shading roller 26; and a control part which generates the white reference data to be used for shading correction of output of the line sensor on the basis of the output of the line sensor when reading the peripheral surface of the shading roller 26, and determines whether the white reference data is valid or invalid on the basis of detection output by the document sensors 28 and 29 when the line sensor reads the shading roller.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image reading apparatus and an image forming apparatus, and more particularly to a technique for generating white reference data used for shading correction.

  As an image reading apparatus, an apparatus that is used alone or mounted on an image forming apparatus or the like is known. For example, an apparatus that pulls out and conveys a document from a document feed tray and reads an image of the document by an image reading unit is known. Further, the white reference member is read by the image reading unit, white reference data is generated based on the output of the image reading unit at this time, and when reading the image of the original, the white reference data is used to read the image reading unit. AGC processing for controlling the output gain is performed to perform shading correction. For example, in Patent Document 1, a white reference plate is used as a white reference member, and white reference data is generated based on an output of an image reading unit that reads the white reference plate.

JP 2003-207972 A

  By the way, a shading roller may be used as the white reference member. In this case, the shading roller is disposed opposite to the image reading unit, and while rotating the shading roller, the peripheral surface of the shading roller is read by the image reading unit, and white reference data is generated based on the output of the image reading unit at this time. However, when a piece of paper or the like remains in the vicinity of the shading roller when reading the peripheral surface of the shading roller, if the shading roller is rotated, or if the conveyance roller for document conveyance is rotated together with the shading roller, the A piece of paper or the like enters between the image reading unit and the shading roller and is read by the image reading unit, which may cause an error in the white reference data. For example, when a sticky note attached to a document is peeled off during reading of the document and remains in the vicinity of the shading roller, the sticky note enters between the image reading unit and the shading roller and is read by the image reading unit. In some cases, an error occurs in the white reference data.

  Such an error in the white reference data causes a decrease in the accuracy of the AGC process, and degrades the quality of the original image read by the image reading apparatus.

  The present invention has been made in view of the above circumstances. When white reference data is generated, when a piece of paper or the like enters between the image reading unit and the shading roller, the white reference data is not adopted. The white reference data is used when the image reading unit does not enter between the image reading unit and the shading roller, and the image quality of the original read by the image reading apparatus is maintained.

An image reading apparatus according to one aspect of the present invention includes a document conveying unit,
An image reading unit for reading one side of the document conveyed by the document conveying unit;
A white shading roller disposed to face the image reading unit;
A drive unit for rotating the shading roller;
A paper piece sensor for detecting a paper piece on at least one of the upstream side or the downstream side in the conveyance direction of the document with respect to the shading roller;
Based on the output of the image reading unit when reading the peripheral surface of the shading roller, generating white reference data used for shading correction of the output of the image reading unit when reading the image of the document, A control unit that determines whether the white reference data is valid or invalid based on a detection output by the paper piece sensor when the image reading unit is reading the peripheral surface of the shading roller.

  An image forming apparatus according to an aspect of the present invention includes the image reading apparatus according to the present invention, and an image forming unit that records an image of the document read by the image reading apparatus on a recording sheet.

  According to the present invention, when white reference data is generated, if a piece of paper or the like enters between the image reading unit and the shading roller, the white reference data can be prevented from being adopted. The white reference data can be adopted when no intrusion occurs. As a result, white reference data used for AGC processing can be accurately acquired and accurate AGC processing can be performed, so that the quality of an image of a document read by the image reading apparatus can be maintained.

1 is a cross-sectional view illustrating an image forming apparatus including an image reading apparatus according to an embodiment of the present invention. It is sectional drawing which shows an image reading apparatus. It is sectional drawing which shows the back surface image reading part in an image reading apparatus. 2 is a functional block diagram illustrating a main internal configuration of the image forming apparatus. FIG. It is a flowchart which shows the process at the time of producing | generating the white reference data used for the shading correction of the output of a 2nd reading part. It is a flowchart which shows the error alerting | reporting process at the time of determination of invalidity of the white reference data which concerns on a back surface image reading part.

  Hereinafter, an image reading apparatus and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating an image forming apparatus including an image reading apparatus according to an embodiment of the present invention.

  An image forming apparatus 1 according to an embodiment of the present invention is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes an apparatus main body 11 including an operation unit 47, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, an image reading device 5, and the like.

  An operation unit (an example of an input unit) 47 receives instructions such as an image forming operation execution instruction and a document reading operation execution instruction from an operator regarding various operations and processes that can be executed by the image forming apparatus 1. The operation unit 47 includes a display unit (an example of a notification unit) 473 that displays operation guidance to the operator.

  When the image forming apparatus 1 performs the image forming operation, the image forming unit 12 applies the paper P as a recording medium fed from the paper feeding unit 14 based on the image data created by the document reading operation. A toner image is formed. When performing color printing, the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 respectively A toner image is formed on the photosensitive drum 121 by charging, exposure, and development processes based on an image composed of each color component constituting data, and the intermediate transfer belt 125 is transferred by the primary transfer roller 126 to the toner image. Transfer on top.

  The toner images of the respective colors transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to form a color toner image. The secondary transfer roller 210 passes the toner image of the color formed on the surface of the intermediate transfer belt 125 from the paper supply unit 14 through the conveyance path 190 at a nip N between the intermediate transfer belt 125 and the driving roller 125a. Transfer is performed on the conveyed paper P. Thereafter, the fixing unit 13 fixes the toner image on the paper P to the paper P by thermocompression bonding. The sheet P on which the color image has been formed after the fixing process is completed is discharged to the discharge tray 151.

  FIG. 2 is a cross-sectional view showing an image reading apparatus according to an embodiment of the present invention. As shown in FIG. 2, the image reading device 5 includes a document feeding unit 6, a front surface image reading unit (an example of a second image reading unit in claims) 30, and a back surface built in the document feeding unit 6. An image reading unit (an example of an image reading unit in claims) 40 is provided.

  The document feeding unit 6 is provided on the upper surface of the surface image reading unit 30 so as to be opened and closed by a hinge or the like. The document feeding unit 6 pulls out the documents MS placed on the document feeding tray 21 one by one and removes the document MS from the surface image. It is conveyed through the first platen glass 31 of the reading unit 30. Further, the document feeding unit 6 functions as a document pressing cover that presses the document MS placed on the second platen glass 32 of the surface image reading unit 30. The surface image reading unit 30 reads an image of the surface of the document MS that is conveyed by the document feeding unit 6 and passes over the first platen glass 31 or placed on the second platen glass 32.

  The document feeder 6 includes a document feed tray 21 on which the document MS is placed, a pickup roller 22, a plurality of transport roller pairs 24 disposed along the document transport path 23, a discharge roller pair 25, and a reverse image reading. A shading roller 26, a document discharge tray 27, a first document sensor 28, a second document sensor 29, and the like disposed to face the unit 40 are provided.

  In the document feeding unit 6, the document MS is pulled out from the document feed tray 21 by the pickup roller 22, and the document MS is transported along the document transport path 23 by the plurality of transport roller pairs 24 and the shading roller 26, so that the first platen. The original MS passes through the glass 31 and is discharged to the original discharge tray 27 by the discharge roller pair 25.

  The back image reading unit 40 reads an image on the back surface of the document MS being conveyed by the shading roller 26. The back image reading unit 40 is, for example, a contact image sensor CIS (Contact Image Sensor).

  In the document transport path 23, the document MS passes between the shading roller 26 and the back image reading unit 40 after the second document sensor 29 detects the leading edge of the document MS. In response to the detection timing of the leading edge of the document MS by the second document sensor 29, the back surface image reading unit 40 starts reading the image on the back surface of the document MS. Further, after the leading edge of the document MS is detected by the first document sensor 28, the document MS passes over the first platen glass 31. In accordance with the detection timing of the leading edge of the document MS by the first document sensor 28, the surface image reading unit 30 starts reading the image on the surface of the document MS.

  The first document sensor 28 and the second document sensor 29 are, for example, a reflection type photosensor or a transmission type photosensor formed by combining a light emitting element and a light receiving element. The first document sensor 28 and the second document sensor 29 are examples of a paper piece sensor.

  The surface image reading unit 30 includes a first platen glass 31, a second platen glass 32, a white reference plate 33, a carriage 34, an optical system unit 35, a condenser lens 36, a CCD (Charge Coupled Device) sensor 37, and the like. Yes.

  The carriage 34 includes a line-shaped LED (Light Emitting Diode) array 34 </ b> A that irradiates light on the document MS and a mirror 34 </ b> C that reflects light reflected by the document MS.

  The optical system unit 35 includes a mirror 35A and a mirror 35B. The mirror 35 </ b> A receives the light reflected by the mirror 34 </ b> C of the carriage 34 and further changes the direction downward substantially vertically. The mirror 35 </ b> B further changes the direction of the light reflected by the mirror 35 </ b> A in the substantially horizontal direction and guides it to the CCD sensor 37 through the condenser lens 36.

  The carriage 34 and the optical system unit 35 are reciprocated in the sub-scanning direction orthogonal to the main scanning direction along the rails by a mechanism (not shown).

  Here, when the surface of the document MS is read by the surface image reading unit 30 while the document MS is conveyed by the document feeding unit 6, the carriage 34 and the optical system unit 35 are positioned as shown in FIG. In this state, in the document feeder 6, the document MS is pulled out from the document feed tray 21, passes over the first platen glass 31, and is further discharged to the document discharge tray 27.

  At this time, in the surface image reading unit 30, the light of the LED array 34 </ b> A of the carriage 34 is irradiated on the surface of the document MS passing over the first platen glass 31, and the light reflected on the surface of the document MS is reflected on the carriage 34. Reflected by the mirror 34C. Further, this light is reflected by the mirror 35 </ b> A and the mirror 35 </ b> B of the optical system unit 35 and enters the CCD sensor 37 through the condenser lens 36. The condenser lens 36 forms an image of the surface of the document MS on the light receiving surface of the CCD sensor 37, and the CCD sensor 37 reads the image of the surface of the document MS.

  When reading the document MS placed on the second platen glass 32, the light of the LED array 34A is emitted while moving the carriage 34 and the optical system unit 35 in the sub-scanning direction while maintaining a predetermined speed relationship. The original MS on the second platen glass 32 is irradiated, and the light reflected by the original MS is sequentially reflected by the mirror 34C, the mirror 35A, and the mirror 35B, and is incident on the CCD sensor 37 through the condenser lens 36. 37 reads the image of the document MS.

  Further, the white reference plate 33 is provided between the first platen glass 31 and the second platen glass 32. With the carriage 34 and the optical system unit 35 properly positioned, the white reference plate 33 can be read by the CCD sensor 37, and the LED array 34A of the carriage 34 is turned on to illuminate the white reference plate 33. Based on the output of the CCD sensor 37, white reference data for shading correction is generated, and based on the output of the CCD sensor 37 when the LED array 34A is turned off, black reference data for shading correction is generated. The white reference data and the black reference data are stored in a memory and used for so-called shading correction for controlling the gain of the output of the CCD sensor 37 reading the document MS.

  FIG. 3 is a cross-sectional view showing the back side image reading unit 40 built in the document feeding unit 6. As shown in FIG. 3, the back image reading unit 40 includes a contact glass 41, a linear light source 42, a rod lens array 43, and a line sensor 44.

  When an image on the back side of the document MS is read by the back image reading unit 40 while the document MS is conveyed by the shading roller 26, the light from the light source 42 is irradiated to the back surface of the document MS through the contact glass 41. The light reflected from the back surface is received by the line sensor 44 through the rod lens array 43. The rod lens array 43 forms an image of the back surface of the document MS on the light receiving surface of the line sensor 44, and the line sensor 44 reads the image of the back surface of the document MS.

  Further, the shading roller 26 functions as a white reference. While turning the shading roller 26, the light source 42 is turned on, and white reference data for AGC processing and shading correction is generated based on the output of the line sensor 44 reading the peripheral surface of the shading roller 26, Further, black reference data for shading correction is generated based on the output of the line sensor 44 when the light source 42 is turned off. The white reference data and the black reference data are stored in the memory and used for shading correction for controlling the gain of the output of the line sensor 44 reading the document MS.

  Next, a configuration related to the control of the image forming apparatus 1 will be described. FIG. 4 is a functional block diagram showing the main internal configuration of the image forming apparatus 1. 4, the image forming apparatus 1 includes a control unit 60, an image reading device 5, a fixing unit 13, an image forming unit 12, an operation unit 47, an image memory 62, an HDD 63, a facsimile communication unit 64, a network interface unit 66, and the like. It is prepared for. In addition, the same code | symbol is attached | subjected to the same thing as the component demonstrated using FIG.

  The control unit 60 includes a CPU (Central Processing Unit), a RAM, a ROM, a dedicated hardware circuit, and the like. The control unit 60 includes a control unit 61.

  The control unit 61 is connected to the control unit 60, the image reading device 5, the fixing unit 13, the image forming unit 12, the operation unit 47, the image memory 62, the HDD 63, the facsimile communication unit 64, the network interface unit 66, and the like. Control is performed to control the entire image forming apparatus 1.

  The image reading device 5 includes a document feeding unit 6, a front image reading unit 30, a back image reading unit 40, a first document sensor 28, a second document sensor 29, a shading roller 26 (FIG. 3), and each conveyance roller pair 24. A drive motor 39, which is a drive source of

  In such a configuration, the user can select and operate any one of the facsimile communication function, the copy function, the printer function, and the scanner function by operating the operation unit 47.

  For example, when the start of reading one side (only the front side) of the document MS is instructed by the operation of the operation unit 47, the control unit 61 causes the document feeding unit 6 to convey the document MS and causes the surface image reading unit 30 to perform the reading. The image on the surface of the document MS is read. For example, in the case of a copy operation, the control unit 61 causes the image forming unit 12 or the like to print the image obtained by the reading on one side of the recording paper. When the start of double-sided reading of the document MS is instructed by the operation of the operation unit 47, the control unit 61 conveys the document MS by the document feeding unit 6, and the back surface image reading unit 40 causes the back side of the document MS to be scanned. The image is read, and then the image on the surface of the document MS is read by the surface image reading unit 30. For example, in the case of a copy operation, the control unit 61 causes the image forming unit 12 or the like to print an image obtained by the reading on both sides of the recording paper.

  By the way, while rotating the shading roller 26, the peripheral surface of the shading roller 26 is read by the line sensor 44 of the back surface image reading unit 40, and the white reference data is generated based on the output of the line sensor 44. When a foreign matter such as the like enters between the back image reading unit 40 and the shading roller 26 and the paper piece is read by the line sensor 44, an error occurs in the white reference data.

  When a piece of paper or the like remains in the vicinity of the shading roller 26, the piece of paper or the like is conveyed by the shading roller 26 and enters between the back surface image reading unit 40 and the shading roller 26, and the piece of paper or the like is read by the line sensor 44. .

  Further, since the driving mechanism of the shading roller 26 is shared with each pair of transport rollers 24 and the like, each pair of transport rollers 24 and the like rotate together with the shading roller 26. For this reason, even if a piece of paper or the like remains away from the shading roller 26 on the upstream side in the conveyance direction of the document MS, the piece of paper or the like is conveyed from the upstream side in the conveyance direction to the downstream side in the conveyance direction via the shading roller 26. A piece of paper or the like may be read by the line sensor 44.

  Therefore, in the present embodiment, when the peripheral surface of the shading roller 26 is read by the line sensor 44 of the back surface image reading unit 40, the control unit 61 is based on the detection outputs of the first document sensor 28 and the second document sensor 29. The white reference data is determined to be valid or invalid based on the result of the presence or absence of a piece of paper. That is, the control unit 61 determines that there is no error in the white reference data when both the first document sensor 28 and the second document sensor 29 do not detect a piece of paper, and determines that the white reference data is valid. In addition, when a piece of paper or the like is detected in at least one of the first document sensor 28 and the second document sensor 29, it is possible that an error has occurred in the white reference data, so the white reference data is determined to be invalid.

  As described above, the first document sensor 28 and the second document sensor 29 are a reflection type photosensor or a transmission type photosensor provided for detecting the leading edge of the document MS. The presence or absence of a piece of paper or the like can be determined based on the detected output.

  The first document sensor 28 and the second document sensor 29 are provided at different positions in the direction orthogonal to the transport direction of the document paper MS. For this reason, the detection area of a paper piece etc. by the 1st original sensor 28 and the 2nd original sensor 29 is wide, and the possibility of detection of a paper piece etc. is high. The first document sensor 28 is located near the back image reading unit 40 and is disposed in the document transport path 23 upstream of the back image reading unit 40 in the document transport direction. The second document sensor 29 is disposed in the document transport path 23 at a position close to the back image reading unit 40 and downstream of the back image reading unit 40 in the document transport direction.

  In order to determine whether white reference data is valid or invalid, the control unit 61, the first document sensor 28, and the second document sensor 29 are used. The control unit 61 controls the image forming apparatus 1. It is an existing one. The first document sensor 28 and the second document sensor 29 are already provided for setting the timing for starting the reading of the document MS by the back surface image reading unit 40. For this reason, it is not necessary to add special parts or the like, and it is only necessary to store a program corresponding to the flowchart shown in FIG.

  Next, a processing procedure for determining whether the white reference data generated based on the output of the line sensor 44 of the back surface image reading unit 40 as described above is valid or invalid will be described with reference to the flowchart shown in FIG.

  The white reference data used for the AGC process is generated in advance, for example, when the image forming apparatus 1 is turned on, when returning from the standby state, or when reading of the document MS is instructed by the operation of the operation unit 47. Is started at the timing.

  First, at such timing, the control unit 61 starts generating white reference data used for the AGC process (step S101). That is, the drive motor 39 is rotated to rotate the shading roller 26 (step S102), the peripheral surface of the shading roller 26 is illuminated by the light source 42 of the back surface image reading unit 40, and the shading roller 26 is illuminated by the line sensor 44. The peripheral surface is read and white reference data for shading correction is generated based on the output of the line sensor 44.

  At this time, the control unit 61 determines the presence or absence of a piece of paper or the like based on the detection outputs of the first document sensor 28 and the second document sensor 29 (step S103), and the generation of the white reference data used for the AGC process is completed. Whether or not (step S104). When the first original sensor 28 and the second original sensor 29 do not detect a piece of paper or the like, the control unit 61 determines that there is no piece of paper or the like (step S103 “No”), and until the generation of the reference data is completed (step S103 “No”). Step S104 “No”) and Steps S103 and 104 are repeated.

  Further, the control unit 61 determines that there is no piece of paper or the like as described above (step S103 “No”), and determines that the generation of the reference data has ended (step S104 “Yes”), the drive motor 39 is turned on. The shading roller 26 is stopped by stopping (step S106). In this case, since there is no piece of paper or the like, no error occurs in the white reference data due to the piece of paper or the like, and the control unit 61 validates the white reference data and stores the white reference data in the HDD 63 or the like. The white reference data is read from the HDD 63 or the like when the back side image reading unit 40 reads the back side image of the document MS, and controls the gain of the output of the line sensor 44 of the back side image reading unit 40. Used for shading correction.

  Further, when a piece of paper or the like is detected in at least one of the first document sensor 28 or the second document sensor 29, the control unit 61 determines that there is a piece of paper or the like (step S103 “Yes”) and uses it for the AGC process. The generation of the white reference data to be performed is interrupted (step S105), the drive motor 39 is stopped, and the shading roller 26 is stopped (step S106). In this case, since there is a piece of paper or the like, there is a high possibility that an error has occurred in the white reference data due to the piece of paper or the like. The control unit 61 invalidates the white reference data and stores the white reference data in the HDD 63 or the like. I won't let you. When the white reference data is invalidated by the control unit 61 as described above, the white reference data validated last time and stored in the HDD 63 or the like when the back side image reading unit 40 reads the image on the back side of the document MS. Are used for AGC processing for controlling the gain of the output of the line sensor 44 of the back surface image reading unit 40 and shading correction.

  As described above, the control unit 61 determines the presence or absence of a piece of paper based on the detection outputs of the first document sensor 28 and the second document sensor 29. When it is determined that there is a piece of paper, an error occurs in the white reference data. The white reference data is invalidated.

  Note that white reference data based on the output of the line sensor 44 of the back surface image reading unit 40 is generated, and white reference data based on the output of the CCD sensor 37 of the front surface image reading unit 30 is also generated.

  Next, the error notification process at the time of determining invalidity of the white reference data according to the back surface image reading unit 40 will be described. FIG. 6 is a flowchart showing an error notification process at the time of determining invalidity of the white reference data according to the back surface image reading unit 40.

  The control unit 61 stops the generation of the white reference data as described above, and determines that the white reference data acquired by the back surface image reading unit 40 is invalid (YES in S201), and the operation unit 47 by the user. When a double-sided scanning instruction is input by the operation (YES in S202), that is, when an instruction to acquire a document image by scanning by the back-side image reading unit 40 is input, the back-side image reading unit 40 and the front side The reading operation by the image reading unit 30 is prohibited and stopped (S203), and an error message for the user (for example, the document reading operation is stopped or white reference data acquisition failure is displayed) is displayed on the display unit 473. (S204).

  On the other hand, when the control unit 61 determines that the white reference data acquired by the back surface image reading unit 40 is valid (NO in S201), or when a single-side reading instruction is input by the operation of the operation unit 47 by the user. (NO in S202), that is, when an instruction to acquire a document image by only reading by the front image reading unit 30 is input, the reading operation prohibiting process is not performed and the error message is displayed on the display unit 473. I won't let you.

  As a result, the user can easily understand that the image on the back side of the document MS cannot be read and that the work of removing a piece of paper in the vicinity of the back image reading unit 40 is necessary.

  As described above, in this embodiment, when the shading roller 26 is read by the line sensor 44 of the back surface image reading unit 40, when it is determined that there is a piece of paper or the like based on the detection output of the first document sensor 28 or the second document sensor 29, Since there is a high possibility that an error occurs in the white reference data, the white reference data is not stored and it is determined that the white reference data is invalid. As a result, the use of white reference data in which an error has occurred can be avoided, and the quality of the image of the document read by the image reading device 5 will not deteriorate.

  Further, an error is displayed on the display unit 473 only when double-sided scanning of the document MS is instructed by the operation of the operation unit 47 and the image on the back side of the document MS is read by the back surface image reading unit 40, or Since the reading operation of the document MS by the image reading device 5 is prohibited, when a document image is acquired only by reading by the front surface image reading unit 30, the document image can be smoothly displayed without stopping the reading operation. Can be acquired.

  In the above embodiment, an example in which the first document sensor 28 and the second document sensor 29 are provided as sensors for detecting a piece of paper or the like is shown. However, only one of the first document sensor 28 or the second document sensor 29 is provided. You may make it prepare. In this case, in step S103 described above, the control unit 61 determines whether or not there is a paper piece depending on whether or not a paper piece or the like is detected by one of the first document sensor 28 or the second document sensor 29 provided. Determine.

  Further, the existing first document sensor 28 and second document sensor 29 are used as sensors for detecting a piece of paper or the like, but a dedicated sensor for detecting a piece of paper or the like may be provided.

  Further, the control unit 61 controls the entire image forming apparatus 1 including the image reading device 5. When the image reading device 5 is used alone, the image reading device 5 itself is included in the image reading device 5. It is only necessary to provide a control unit that controls the white balance data and a necessary storage unit.

  The configuration and processing described with reference to FIGS. 1 to 6 are only an embodiment of the present invention, and the present invention is not limited to the configuration and processing.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Image reader 6 Document feeding part 26 Shading roller 28 1st document sensor (paper piece sensor)
29 Second document sensor (paper piece sensor)
30 Surface image reading unit 39 Drive motor (drive unit)
40 Back Image Reading Unit 47 Operation Unit 61 Control Unit 473 Display Unit

Claims (7)

A document transport section;
An image reading unit for reading one side of the document conveyed by the document conveying unit;
A white shading roller disposed to face the image reading unit;
A drive unit for rotating the shading roller;
A paper piece sensor for detecting a paper piece on at least one of the upstream side and / or the downstream side in the conveyance direction of the document with respect to the shading roller;
Based on the output of the image reading unit when reading the peripheral surface of the shading roller, generating white reference data used for shading correction of the output of the image reading unit when reading the image of the document, An image reading apparatus comprising: a control unit that determines whether the white reference data is valid or invalid based on a detection output by the paper piece sensor when the image reading unit is reading the peripheral surface of the shading roller.   The control unit determines that the white reference data is invalid when a paper piece is detected by at least one of an upstream side or a downstream side in the document transport direction with respect to the shading roller by the paper piece sensor. The image reading apparatus described in 1.   The image reading apparatus according to claim 1, wherein when the white reference data is determined to be invalid by the control unit, white reference data determined to be valid last time is used for the shading. A second image reading unit for reading the other side of the document conveyed by the document conveying unit;
An input unit for inputting a double-sided reading instruction for causing the image reading unit and the second image reading unit to read images on both sides of the document;
The image reading unit is provided for reading the back side of the document, and the second image reading unit is provided for reading the front side of the document.
2. The control unit according to claim 1, wherein the control unit determines whether the white reference data is invalid and performs a preset process corresponding to the invalidity determination only when the double-side reading instruction is input to the input unit. The image reading apparatus described. It further includes a notification unit that notifies the user,
The image reading apparatus according to claim 4, wherein the control unit causes the notification unit to notify an error as the preset process.   The image according to claim 5, wherein the control unit does not cause the notification unit to report an error when a single-side reading instruction for reading the surface of the document by the second image reading unit is input to the input unit. Reader. The image reading apparatus according to any one of claims 1 to 6,
An image forming apparatus comprising: an image forming unit that records an image of the document read by the image reading apparatus on a recording sheet.

Images