Image reading device and image forming device

Abstract

To generate shading data that is not affected by foreign substances, such as dirt and scratches on a flat-shaped density reference member.SOLUTION: An image reading device comprises: irradiation means that irradiates a document with light; reading means that condenses and reads reflected light from the document; a density reference member that is provided opposite to the reading means; moving means that moves the density reference member in a main scanning direction; and a shading data generation unit that acquires data obtained by removing the influence of foreign substances on the density reference member from data read while the density reference member is moved in the main scanning direction by the moving means, and generates shading data.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image reading device and an image forming device. [Background technology]

[0002] Conventionally, in order to efficiently read multiple original documents, image processing devices such as scanners use an ADF (Auto Document Feeder) to separate the multiple original documents one by one and transport them to the reading position of a reading unit, where the images of the original documents are read.

[0003] In recent years, a one-path ADF has been developed that incorporates a second reading unit within the ADF in order to simultaneously read both sides of a document in one document transport. In terms of its mechanical configuration, the one-path ADF has a density reference member required for performing shading correction, which is installed on the document transport path in a position facing the second reading unit.

[0004] The density reference member of the one-pass ADF is placed on the document transport path, and can become dirty with toner, ink, or paper dust adhering to the document, or can be damaged by rubbing the document. If the one-pass ADF performs shading correction using a density reference member with dirt or other contaminants, it will be unable to generate shading data correctly. As a result, the one-pass ADF will output an abnormal image with vertical streaks in the areas where dirt or other contaminants are adhering as the scanned image.

[0005] Patent Document 1 discloses a technique for generating shading data from image data of a surface free of dirt or other foreign matter by using image data acquired by rotating a roller-shaped density reference member. Patent Document 2 discloses a technique for generating shading data by using image data acquired while moving a flat-plate-shaped density reference member in the main scanning direction or sub-scanning direction, while avoiding the influence of dirt or other foreign matter. Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technique disclosed in Patent Document 1 has a problem in that a gap exists between the roller-shaped density reference member and the document transport guide, which makes the document prone to paper jams. In particular, when a curled document is used, the document is prone to paper jams.

[0007] Furthermore, the technique disclosed in Patent Document 2 has a problem in that, due to the constraints of the mechanical configuration, when the moving distance of the flat plate-shaped concentration reference member is short, the influence of foreign matter cannot be completely eliminated.

[0008] The present invention has been made in view of the above, and has an object to generate shading data that is not affected by foreign matter such as stains or scratches on a flat density reference member. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the present invention provides an image forming apparatus comprising: an irradiating means for irradiating a document with light; a reading means for collecting and reading light reflected from the document; a flat density reference member provided opposite the reading means; a moving means for moving the density reference member in a main scanning direction; and a shading data generating section for generating shading data in which foreign matter on the density reference member has been removed by executing a predetermined process on data read while the density reference member is being moved in the main scanning direction by the moving means. the shading data generating unit extracts an arbitrary number of lines having high output values ​​while reading the density reference member, and generates shading data. It is characterized by: Effect of the Invention

[0010] According to the present invention, it is possible to generate shading data that is not affected by foreign matter such as stains or scratches on a flat density reference member. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus including a sheet conveying device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of the ADF. [Diagram 3] FIG. 3 is a diagram showing the positional relationship between the white guide plate and the guide member. [Figure 4] FIG. 4 is a block diagram showing a control configuration of the ADF. [Diagram 5] FIG. 5 is a diagram showing the configuration of a moving means for moving the white guide plate. [Figure 6] FIG. 6 is a block diagram showing a control configuration of the second reading unit of the ADF. [Figure 7] FIG. 7 is a block diagram showing the functional configuration of the image processing circuit. [Figure 8] FIG. 8 is a block diagram showing the functional configuration of the foreign matter removal and shading data generation unit. [Figure 9] FIG. 9 is a diagram showing an example of movement of the white guide plate. [Figure 10] FIG. 10 is a diagram illustrating an example of a foreign matter removal process. [Figure 11] FIG. 11 is a diagram showing a specific operation of removing foreign matter and generating shading data. [Figure 12] FIG. 12 is a block diagram illustrating a modified example of the functional configuration of the image processing circuit according to the first embodiment. In FIG. [Figure 13] FIG. 13 is a block diagram of a functional configuration of a foreign matter removal and shading data generation unit according to the second embodiment. As shown in FIG. [Figure 14] FIG. 14 is a diagram showing a specific operation of removing foreign matter and generating shading data. [Figure 15] FIG. 15 is a block diagram illustrating a functional configuration of a foreign matter removal and shading data generation unit according to the third embodiment. As illustrated in FIG. [Figure 16] FIG. 16 is a diagram showing a specific operation of removing foreign matter and generating shading data. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image reading apparatus and an image forming apparatus will be described in detail with reference to the accompanying drawings.

[0013] (First embodiment) 1 is a schematic diagram of an image forming apparatus including a sheet conveying device according to a first embodiment. In this embodiment, the image forming apparatus is applied to a multifunction machine having at least two of a copy function, a printer function, a scanner function, and a facsimile function.

[0014] First, the configuration will be described. As shown in Fig. 1, a multifunction machine 1 as an image forming device includes an automatic document feeder (hereinafter simply referred to as ADF (Auto Document Feeder)) 2 as a sheet conveying device, a paper feed section 3, an image reading section 4, and an image forming section 5. The ADF 2 and the image reading section 4 function as an image reading device.

[0015] The ADF 2 includes a document tray 11 and a transport unit 13 including various rollers. The ADF 2 transports a document as a sheet placed on the document tray 11 by the transport unit 13 onto the slit glass 7, and the image reading unit 4 reads the front side image of the document through the slit glass 7. Next, the ADF 2 transports the document after the front side image has been read to the second reading unit 101, and the second reading unit 101 reads the back side image of the document. The ADF 2 passes the document between the slit glass (not shown) of the second reading unit 101 and the white guide plate 70, and then discharges the document to the discharge tray 12.

[0016] The ADF 2 is attached to the image reading unit 4 so as to be able to open and close freely via an opening and closing mechanism (not shown).

[0017] The paper feed section 3 has paper feed cassettes 21, 22 that store recording paper as recording media of different paper sizes, and a paper feed means 23 consisting of various rollers that transport the recording paper stored in the paper feed cassettes 21, 22 to the image formation position of the image forming section 5.

[0018] The image reading unit 4 includes a first carriage 25 carrying a light source and a first mirror member, a second carriage 26 carrying a second mirror member and a third mirror member, an imaging lens 27, and an imaging unit 28 consisting of a CCD or the like.

[0019] When the image reading unit 4 reads an original document using the ADF 2, it stops the first carriage 25 and the second carriage 26 below the slit glass 7. Thereafter, the image reading unit 4 irradiates light onto the original document passing over the slit glass 7 using a light source mounted on the first carriage 25, causes the first to third mirror members mounted on the first carriage 25 and the second carriage 26 to reflect the light reflected from the original document, and causes the reflected light to be imaged by the imaging lens 27 and read by the imaging unit 28.

[0020] In addition, when reading a document placed on contact glass 8, which has a larger area than slit glass 7, image reading unit 4 moves first carriage 25 and second carriage 26 in the left-right direction (sub-scanning direction) below contact glass 8 in Figure 1, while irradiating light onto the document placed on contact glass 8 using a light source mounted on first carriage 25, and folding back the reflected light from the document using first to third mirror members mounted on first carriage 25 and second carriage 26, and focusing the reflected light using imaging lens 27 to be read by imaging unit 28.

[0021] The image forming unit 5 constitutes an image forming means. The image forming unit 5 includes an exposure device 31, a plurality of photoconductor drums 32, a developing device 33 including toners of different colors, cyan, yellow, magenta, and black, a transfer belt 34, and a fixing device 35.

[0022] Based on the image read by the imaging unit 28, the image forming unit 5 exposes the photosensitive drum 32 using the exposure device 31 to form a latent image on the photosensitive drum 32, and then develops the latent image by supplying toner of a different color to the photosensitive drum 32 using the developing device 33.

[0023] Then, the image forming unit 5 transfers the image developed on the photosensitive drum 32 by the transfer belt 34 onto the recording paper supplied from the paper feed unit 3, and then the fixing device 35 melts the toner of the toner image transferred onto the recording paper, thereby fixing the color image onto the recording paper.

[0024] The ADF 2 will be described in detail with reference to Fig. 2. Fig. 2 is a schematic diagram of the ADF 2.

[0025] 2, the document tray 11 has a movable document table 41 and a pair of side guide plates 42. The movable document table 41 constitutes the leading edge of the document tray 11 in the paper feed direction, and rotates in the vertical direction (in the direction of the arrow ab in the figure) with its base end as a fulcrum. In this way, the document tray 11 can adjust the leading edge of the document placed on the document tray 11 in the paper feed direction to an appropriate height by rotating the movable document table 41.

[0026] An appropriate paper feed position sensor 87 is provided above the leading edge of movable document table 41. The appropriate paper feed position sensor 87 detects whether the leading edge in the paper feed direction of the document placed on document tray 11 is held at an appropriate height, that is, an appropriate paper feed position. Note that the appropriate paper feed position in this embodiment refers to the position where the topmost document in the document stack comes into contact with pickup roller 61, which will be described later.

[0027] A home position sensor 88 is provided below the tip of the movable original table 41. The home position sensor 88 detects whether or not the movable original table 41 is at the home position.

[0028] Original length detection sensors 89, 90 are provided in the original tray 11 to detect whether the orientation of at least originals of the same size is portrait or landscape. The original length detection sensors 89, 90 are provided spaced apart in the feeding direction. The original length detection sensors 89, 90 may be reflective sensors that detect the length of the originals by optical means without contacting the originals, or contact-type actuator-type sensors that come into contact with the originals so as to be able to detect even a single sheet of the original.

[0029] The pair of side guide plates 42 are erected so as to position the document placed on the document tray 11 in the left-right direction relative to the paper feed direction. One side of the pair of side guide plates 42 is slidable in the left-right direction relative to the paper feed direction. This allows documents of different sizes to be placed on the document tray 11.

[0030] Therefore, a stack of originals set with the original surfaces facing upward on the original tray 11 including the movable original table 41 is positioned by the pair of side guide plates 42 in the left and right directions relative to the original feeding direction.

[0031] A set filler 43 that rotates when a document is placed on the document tray 11 is provided on the fixed side of the pair of side guide plates 42. A document set sensor 82 that detects that a document has been placed on the document tray 11 is provided at the bottom of the movement trajectory of the tip of the set filler 43. That is, when a document is placed on the document tray 11, the set filler 43 rotates and the tip of the set filler 43 comes off the document set sensor 82, thereby detecting the placement of the document.

[0032] Therefore, the setting of the above-mentioned document stack is detected by the set feeler 43 and the document set sensor 82, and is transmitted to the main body control unit 105 (see FIG. 4) by the I / F 107 (see FIG. 4).

[0033] Furthermore, when the above-mentioned set filler 43 and document set sensor 82 detect that a document has been set, the controller 100 (see FIG. 4) rotates the bottom plate lifting motor 96 in the forward direction to lift the movable document table 41 so that the top surface of the document stack comes into contact with the pickup roller 61 described later.

[0034] The conveying section 13 of the ADF 2 includes a separation and feeding section 51, a pull-out section 52, a turning section 53, a first reading and conveying section 54, a second reading and conveying section 55, and a paper ejection section 56.

[0035] The separation and feeding section 51 has a pickup roller 61 arranged near the paper feed port, and a paper feed belt 62 and a reverse roller 63 arranged to face each other across the transport path. The pickup roller 61 is supported by a support arm member 64 attached to the paper feed belt 62, and rotates in the vertical direction (the direction cd in the figure) between a contact position where it contacts the document stack and a separated position away from the document stack via a cam mechanism (not shown).

[0036] Therefore, when the print key is pressed on the main body operation unit 106 (see FIG. 4) and a document feed signal is sent from the main body control unit 105 to the controller 100 via the I / F 107, the pickup roller 61 is rotated by the forward rotation of the feed motor 93 (see FIG. 4) and picks up several documents (ideally one document) on the document tray 11. The rotation direction is the direction in which the topmost document is transported to the document feed port.

[0037] The paper feed belt 62 rotates in the feeding direction, and the reverse roller 63 rotates in the opposite direction to the feeding direction. When multiple documents are fed, the reverse roller 63 rotates in the opposite direction to the paper feed belt 62. When the reverse roller 63 is in contact with the paper feed belt 62 or when only one document is being conveyed, the reverse roller 63 rotates together with the paper feed belt 62 due to the action of a torque limiter (not shown).

[0038] More specifically, the reverse roller 63 contacts the paper feed belt 62 with a predetermined pressure, and when in direct contact with the paper feed belt 62 or in contact with one document through the reverse roller 63, the reverse roller 63 rotates counterclockwise following the rotation of the paper feed belt 62. In addition, in the unlikely event that two or more documents enter between the paper feed belt 62 and the reverse roller 63, the reverse roller 63 is set so that the force of the reverse roller 63 to rotate is lower than the torque of the torque limiter, and the reverse roller 63 rotates in the clockwise direction, which is the normal rotation direction, and pushes back the excess documents. By the reverse roller 63 operating in this manner, double feeding of documents is prevented.

[0039] In this way, the separation and feeding section 51 sends out a document into the paper feed opening by the pickup roller 61 rolling over the topmost document in the stack of documents placed on the document tray 11, and when multiple documents are fed, they are separated and sent out by the paper feed belt 62 and reverse roller 63.

[0040] The pull-out unit 52 has pull-out rollers 65 consisting of a pair of rollers arranged to sandwich the transport path. The pull-out unit 52 performs primary abutment alignment of the sent-out document by driving timing of the pull-out roller 65 and the pickup roller 61, and pulls out and transports the document after alignment. In addition, an abutment sensor 84 is arranged on the transport path between the separation feeding unit 51 and the pull-out unit 52. The abutment sensor 84 detects the leading edge of the document transported by the paper feed belt 62.

[0041] Therefore, the document separated into one sheet by the action of the feed belt 62 and the reverse roller 63 is further transported by the feed belt 62, and its leading edge is detected by the abutment sensor 84. Then, the transported document abuts against the pull-out roller 65, which is at rest.

[0042] Thereafter, the document is transported a predetermined distance from the detection of the above-mentioned abutment sensor 84, and when the document is pressed against the pull-out roller 65 with a predetermined amount of flexure, the feed motor 93 is stopped, thereby stopping the drive of the feed belt 62. At this time, the controller 100 rotates the pickup motor 92 to move the pickup roller 61 away from the top surface of the document, and the document is transported only by the transport force of the feed belt 62. As a result, the leading edge of the document enters the nip between the upper and lower roller pairs of the pull-out roller 65, and the leading edge of the document is aligned (skew correction).

[0043] When the skew correction is performed, the controller 100 drives the feed motor 93 in the reverse direction to rotate the pull-out roller 65 and the intermediate roller 66 described later. At this time (when the feed motor 93 rotates in the reverse direction), the pull-out roller 65 and the intermediate roller 66 are driven, but the pickup roller 61 and the feed belt 62 are not driven.

[0044] Next, the turn unit 53 has an intermediate roller 66 and a reading entrance roller 67, which are a pair of rollers arranged to sandwich a curved portion that curves from the top to the bottom of the transport path. The turn unit 53 turns the document drawn and transported by the intermediate roller 66 by transporting the curved portion, and transports the document with its front surface facing downward to the vicinity of the slit glass 7 by the reading entrance roller 67. In addition, an original width sensor 85 is arranged on the transport path between the pull-out unit 52 and the turn unit 53. The original width sensor 85 is composed of a plurality of light receiving elements arranged in the width direction of the original, and detects the original width based on the light receiving result from irradiated light provided at opposing positions across the transport path.

[0045] Therefore, the size of the document conveyed to the intermediate rollers 66 by the pull-out rollers 65 is detected by the document width sensor 85 in the width direction perpendicular to the document conveying direction.

[0046] In addition, when the original is transported from the pull-out section 52 to the turn section 53 by driving the pull-out rollers 65 and the intermediate rollers 66, the transport speed in the pull-out section 52 is set faster than the transport speed in the first reading transport section 54 described below, thereby shortening the processing time for transporting the original to the first reading transport section 54.

[0047] Next, a reading entrance sensor 86 is disposed on the transport path between the intermediate rollers 66 and the reading entrance rollers 67. The reading entrance sensor 86 detects the leading edge of the document transported from the intermediate rollers 66 to the reading entrance rollers 67.

[0048] Here, when the leading edge of the document is detected by the above-mentioned reading entrance sensor 86, the controller 100 starts to decelerate the document transport speed to make the document transport speed the same as the reading transport speed before the leading edge of the document enters the nip between the upper and lower roller pairs of the reading entrance rollers 67. At the same time, the controller 100 drives the reading motor 94 in the forward direction to drive the reading entrance rollers 67, the first reading exit rollers 69, and the second reading exit rollers 71.

[0049] The first reading transport section 54 has a first reading roller 68 arranged at a position facing the slit glass 7 across the transport path, and a first reading exit roller 69 consisting of a pair of rollers arranged to sandwich the transport path after reading is completed. The first reading transport section 54 transports the document transported close to the slit glass 7 while bringing the surface of the document into contact with the slit glass 7 by the first reading roller 68, and further transports the document after reading is completed by the first reading exit roller 69.

[0050] A registration sensor 81 is disposed on the transport path between the reading entrance rollers 67 and the first reading rollers 68. The registration sensor 81 detects the leading edge of the document transported by the reading entrance rollers 67 to the first reading transport section 54.

[0051] Therefore, when the leading edge of the document is detected by the registration sensor 81, the controller 100 decelerates at a predetermined conveying distance, temporarily stops the document before the first reading roller 68 and the reading position 20, and transmits a registration stop signal to the main body control unit 105 via the I / F 107. Next, when the controller 100 receives a reading start signal from the main body control unit 105, the controller 100 accelerates the conveying speed to a predetermined conveying speed until the leading edge of the document, which has been stopped in the registration, is guided by the guide member 75 and reaches the reading position 20. The controller 100 transmits a gate signal indicating the effective image area in the sub-scanning direction on the front side to the main body control unit 105 at the timing when the leading edge of the document detected by the pulse count of the reading motor 94 reaches the reading position 20. This gate signal is transmitted until the trailing edge of the document leaves the reading position 20.

[0052] The second reading and conveying section 55 has a second reading section 101 as a reading means for reading the back side of the document, a flat white guide plate 70 arranged opposite the second reading section 101 across the conveying path, and a pair of second reading exit rollers 71 arranged to sandwich the conveying path after reading of the back side of the document is completed. Also, a paper discharge sensor 83 is arranged on the conveying path between the first reading and conveying section 54 and the second reading and conveying section 55. The flat white guide plate 70 is provided in a position close to the guide members 73 and 74, respectively, and forms part of the conveying path together with the guide members 73 and 74.

[0053] The second reading transport section 55 passes the document whose front side has been read between the white guide plate 70 and the reading surface of the second reading section 101, and transports it toward the paper discharge outlet by the second reading outlet rollers 71. When double-sided reading is not performed, the document passes directly through the second reading section 101.

[0054] Next, the paper discharge unit 56 is provided with a pair of paper discharge rollers 72 in the vicinity of the paper discharge outlet. The pair of paper discharge rollers 72 discharge the document conveyed by the second reading outlet rollers 71 onto the paper discharge tray 12.

[0055] Therefore, in the case of single-sided reading, the document that has passed through the first reading and conveying section 54 is guided by the guide member 73 to the second reading and conveying section 55, and is conveyed through the second reading and conveying section 55 to the paper discharge section 56. At this time, when the leading edge of the document is detected by the paper discharge sensor 83, the controller 100 drives the paper discharge motor 95 (see FIG. 4) in the forward direction to rotate the paper discharge roller 72 in the counterclockwise direction. In addition, after the leading edge of the document is detected by the paper discharge sensor 83, the controller 100 counts the pulses of the paper discharge motor 95, and reduces the driving speed of the paper discharge motor 95 just before the rear end of the document leaves the nip portion of the upper and lower roller pairs of the paper discharge roller 72, thereby controlling the document to not fly out when discharged onto the paper discharge tray 12.

[0056] On the other hand, in the case of double-sided reading, the controller 100 counts the pulses of the reading motor 94 (see FIG. 4) after the leading edge of the document is detected by the paper discharge sensor 83. Next, the controller 100 transmits a gate signal indicating the effective image area in the sub-scanning direction to the second reading unit 101 at the timing when the leading edge of the document reaches the second reading unit 101. This gate signal is transmitted until the trailing edge of the document leaves the second reading unit 101. The white guide plate 70 suppresses floating of the document in the second reading unit 101, and also serves as a density reference member for acquiring shading data in the second reading unit 101.

[0057] Here, Fig. 3 is a diagram showing the positional relationship between the white guide plate 70 and the guide members 73 and 74. As shown in Fig. 3, in this embodiment, as described above, the flat white guide plate 70 is used as the density reference member, and a roller-shaped density reference member is not used. Therefore, as shown in Fig. 3, gaps are unlikely to occur in the sub-scanning direction between the white guide plate 70 and the guide members 73 and 74, making it difficult for document paper jams to occur.

[0058] Next, a description will be given of the control configuration of the ADF 2. FIG 4 is a block diagram showing the control configuration of the ADF 2.

[0059] 4, the ADF 2 includes a controller 100 that controls the entire ADF 2. The ADF 2 includes sensors that input signals to the controller 100, such as a registration sensor 81, a document set sensor 82, a paper discharge sensor 83, a bump sensor 84, a document width sensor 85, a reading entrance sensor 86, a paper feed proper position sensor 87, a home position sensor 88, and document length detection sensors 89 and 90. Each of these sensors 81 to 90 is connected to the controller 100.

[0060] The ADF 2 also includes a pickup motor 92, a paper feed motor 93, a reading motor 94, a paper discharge motor 95, a bottom plate lifting motor 96, and a guide moving motor 97 as motors and the like that output signals from the controller 100 to drive and control each part of the ADF 2. Each of the motors 92 to 97 is connected to the controller 100. The bottom plate lifting motor 96 raises and lowers the movable original table 41. The pickup motor 92 moves the pickup roller 61 up and down.

[0061] The paper feed motor 93 rotates and drives the pickup roller 61, the paper feed belt 62, the reverse roller 63, the pull-out roller 65, and the intermediate roller 66. The reading motor 94 rotates and drives the reading entrance roller 67, the first reading roller 68, the first reading exit roller 69, and the second reading exit roller 71. The paper discharge motor 95 rotates and drives the paper discharge roller 72.

[0062] A guide movement motor 97 moves a white guide plate 70 serving as a density reference member in the main scanning direction, which is a direction perpendicular to the document conveying direction.

[0063] The motors 92 to 97 are controlled by a controller 100 based on detection signals from the above-mentioned sensors. The ADF 2 also includes a second reading unit 101 that reads the back side of the document. The second reading unit 101 is connected to the controller 100.

[0064] The white guide plate 70 is provided with a moving means constituted by, for example, a rack and pinion. Here, Fig. 5 is a diagram showing the configuration of the moving means for moving the white guide plate 70. As shown in Fig. 5, the white guide plate 70 is installed on the upper surface of a guide plate moving member 80 so as to be able to slide back and forth in the main scanning direction. The white guide plate 10 has a rack portion 70a formed on one side surface in the longitudinal direction, i.e., in the main scanning direction, which moves the white guide plate 70 in the main scanning direction by meshing with a pinion 71 described later.

[0065] On the other hand, like the white guide plate 70, the guide plate moving member 80 is made of a flat plate and is formed into a substantially rectangular shape with the sub-scanning direction as its short side direction and the main scanning direction as its long side direction, and is adapted to hold the white guide plate 70 slidably in the main scanning direction. Here, the guide plate moving member 80 is provided with, for example, a slide rail (not shown) on the surface facing the white guide plate 70, and the white guide plate 70 slides on this slide rail, thereby enabling the white guide plate 70 to slide back and forth in the main scanning direction.

[0066] Further, a guide movement motor 97 and a pinion 71 are installed on the guide plate moving member 80. The pinion 71 is formed with a toothed portion, and this toothed portion is adapted to mesh with a rack portion 70a formed on the white guide plate 70.

[0067] The guide moving motor 97 is adapted to be rotationally driven in the forward or reverse direction by a signal from the controller 100, and the driving force of the guide moving motor 97 is transmitted to the pinion 71 via a drive belt 72 stretched between the guide moving motor 97 and the pinion 71. In other words, the guide moving motor 97 is adapted to move the white guide plate 70 in the main scanning direction by rotationally driving the pinion 71 via the drive belt 72.

[0068] As described above, in this embodiment, the guide moving motor 97, the pinion 71, and the drive belt 72 constitute the moving means.

[0069] The multifunction device 1 also includes a main body control unit 105 that controls the entire multifunction device 1, and a main body operation unit 106 that performs various input operations and operation instructions. The controller 100 and the main body control unit 105 are connected via an I / F 107, and data such as control signals are exchanged between them.

[0070] The control configuration of the second reading unit 101 will be described with reference to Fig. 6. Fig. 6 is a block diagram showing the control configuration of the second reading unit 101 of the ADF 2.

[0071] 6, the second reading unit 101 includes an image reading unit 4 that includes a light source unit 111, a sensor chip 112, an amplifier 113, an A / D 114, an image processing unit 115, and a frame memory 116. The sensor chip 112 includes a known photoelectric conversion element called a life-size contact image sensor and a condenser lens.

[0072] The second reading unit 101 irradiates light onto the document using a light source unit 111 functioning as an irradiation unit based on a turn-on signal from the controller 100. The second reading unit 101 receives reflected light from the document using each sensor chip 112 functioning as a reading unit, converts the reflected light into an electrical signal, and outputs it.

[0073] The second reading unit 101 amplifies the electrical signals output from each sensor chip 112 using an amplifier 113, converts the analog signals to digital signals using an A / D 114, and performs image processing using an image processing unit 115. The second reading unit 101 stores the signals that have been image-processed by the image processing unit 115 in a frame memory 116.

[0074] The second reading unit 101 also includes an output control circuit 117 that controls the output of signals stored in the frame memory 116 based on a timing signal from the controller 100, and an I / F circuit 118 that outputs the signals output from the output control circuit 117 to the main body control unit 105.

[0075] Therefore, the second reading unit 101 transfers the image data stored in the frame memory 116 to the main body control unit 105 via the output control circuit 117 and the I / F circuit 118. The main body control unit 105 transfers the image data obtained by reading the back side of the document to the image processing circuit 120.

[0076] Moreover, the image processing circuit 120 performs shading correction based on image data obtained when the second reading unit 101 reads the white guide plate 70 as a density reference member.

[0077] Here, the image processing circuit 120 will be described in detail. FIG. 7 is a block diagram showing the functional configuration of the image processing circuit 120. As shown in FIG. 7, the image processing circuit 120 includes an image processing unit (front stage) 1201 and an image processing unit (back stage) 1202. The image processing circuit 120 is an IC (Integrated Circuit) for image processing purposes having hardware elements for image processing, such as an ASIC (Application Specific Integrated Circuit). The image processing unit (front stage) 1201 performs shading correction on image data captured by the second reading unit 101 while reading an original, and outputs the image data to the image processing unit (back stage) 1202. The image processing unit (back stage) 1202 performs color conversion, filter image processing, and the like.

[0078] The image processing unit (front stage) 1201 includes an image sorting unit 1204 and a white correction unit 1205 .

[0079] The image sorting unit 1204 controls the image data (digital) input from the second reading unit 101 so that the image data is sorted in order from the first pixel in the main scanning direction. The image sorting unit 1204 outputs the sorted image data to the white correction unit 1205.

[0080] The white correction unit 1205 generates shading data and performs shading correction using the generated shading data. More specifically, the white correction unit 1205 includes a shading correction unit 1206, a foreign substance removal and shading data generation unit 1207, and a shading data memory 1208.

[0081] The shading correction unit 1206, the details of which will be described later, captures image data captured while the white guide plate 70 is being moved in the main scanning direction, and generates shading data.

[0082] The foreign substance removal and shading data generation unit 1207 functions as a shading data generation unit. The foreign substance removal and shading data generation unit 1207 generates shading data using data without foreign substances, and stores the shading data in the shading data memory 1208.

[0083] Here, the foreign substance removal and shading data generation unit 1207 will be described in detail. Fig. 8 is a block diagram showing the functional configuration of the foreign substance removal and shading data generation unit 1207. As shown in Fig. 8, the foreign substance removal and shading data generation unit 1207 includes a threshold determination unit 1209, a sub-scanning pixel addition unit 1210, a sub-scanning average value calculation unit 1211, and an addition memory 1212.

[0084] The threshold determination unit 1209 outputs only image data within a preset threshold range from the image data read while the white guide plate 70 is moving in the main scanning direction to the downstream sub-scanning pixel addition unit 1210. The threshold value is set taking into consideration unevenness of the white guide plate 70, the illuminance of the light source unit 111 of the second reading unit 101, and the fluctuation over time of the sensor chip 112 of the second reading unit 101.

[0085] The sub-scanning pixel summation unit 1210 adds up the image data that was within the threshold range, pixel by pixel, in the sub-scanning direction, using an addition memory 1212. Then, the sub-scanning pixel summation unit 1210 outputs the total value of each pixel and the line counter of each pixel (the number of times that each pixel has been added in the sub-scanning direction) to the sub-scanning average value calculation unit 1211.

[0086] The sub-scanning average value calculation unit 1211 calculates the average value of each pixel based on the total value of each pixel and the line counter of each pixel. The sub-scanning average value calculation unit 1211 then generates shading data and stores the image data in the shading data memory 1208.

[0087] Next, the white guide plate 70, which is provided opposite the second reading unit 101 and also serves as a density reference member, will be described.

[0088] In conventional technology, image data obtained while moving a flat density reference member in the main scanning direction or sub-scanning direction is used to generate shading data while avoiding the effects of dirt and scratches. However, due to constraints on the mechanical configuration, there was a problem that when the moving distance of the flat density reference member is short, the effects of foreign matter such as dust cannot be completely eliminated.

[0089] Therefore, as described below, the ADF 2 of this embodiment is configured so that the white guide plate 70, which serves as a density reference member, can be moved in the main scanning direction, which is a direction perpendicular to the document transport direction, and it is possible to generate shading data from data read while the white guide plate 70 is moving in the main scanning direction, using data from which the foreign matter removal and shading data generation unit 1207 has removed the effects of foreign matter on the white guide plate 70.

[0090] Fig. 9 is a diagram showing an example of movement of the white guide plate 70. Fig. 9 shows an example in which the white guide plate 70 is shifted to the rear end side in the main scanning direction. As shown in Fig. 9, the controller 100 rotates the guide movement motor 97 to move the white guide plate 70 in the main scanning direction, which is a direction perpendicular to the document transport direction, via a moving means such as an actuator (not shown).

[0091] 9, it is assumed that a foreign object (dirt) is attached near the center in the main scanning direction of the white guide plate 70. The foreign object is, for example, a floating foreign object such as paper powder, and is approximately 2 mm in size.

[0092] Therefore, if a foreign object measuring approximately 2 mm in size is attached to the white guide plate 70, by moving the white guide plate 70 by 2 mm or more in the main scanning direction, it is possible to obtain read data of the white guide plate 70 that is not affected by the foreign object.

[0093] Next, the foreign substance removal process in the foreign substance removal and shading data generation unit 1207 will be described.

[0094] Here, Fig. 10 is a diagram showing an example of the foreign matter removal process. Fig. 10 shows the reading result obtained while moving the white guide plate 70 toward the rear end side in the main scanning direction as shown in Fig. 9. Note that the reading result by the second reading unit 101 shown in Fig. 10 is an example of 8 pixels in the main scanning direction and 4 lines in the sub-scanning direction.

[0095] In the example shown in FIG. 10, the white guide plate 70 is moved (shifted) while reading, but this is not limited to this, and data from a period in which the white guide plate 70 is not moved may also be included.

[0096] In the example shown in Fig. 10, before the white guide plate 70 moves, the position of the foreign matter adhering to the white guide plate 70 is the sixth pixel. Then, as the white guide plate 70 is moved toward the rear end in the main scanning direction, the pixel position at which the second reading unit 101 reads the foreign matter gradually shifts toward the rear end. In the example shown in Fig. 10, the first line of the second reading unit 101 reads the foreign matter at the sixth pixel, and finally, the fourth line of the second reading unit 101 reads the foreign matter on the white guide plate 70 at the eighth pixel.

[0097] Next, a specific operation of foreign substance removal and shading data generation will be described below in the foreign substance removal and shading data generation unit 1207. Fig. 11 is a diagram showing a specific operation of foreign substance removal and shading data generation.

[0098] 11, the result of reading the white guide plate 70 is input to a threshold determination unit 1209 of the foreign substance removal and shading data generation unit 1207. A threshold value that sets a normal range that is not affected by dirt is set in the threshold determination unit 1209. In this embodiment, the threshold value is set to a lower limit of 190 digits and an upper limit of 210 digits. The threshold determination unit 1209 outputs only image data that falls within the threshold range to a sub-scanning pixel addition unit 1210.

[0099] The sub-scanning pixel adder 1210 of the foreign substance removal and shading data generation unit 1207 has two roles, which will be described in detail below.

[0100] (1) Addition of input data First, the sub-scanning pixel summation unit 1210 adds input image data. The flow of this operation is as follows. First line: The input image data is written to the addition memory 1212. Second line: The input image data and the data in the addition memory 1212 are added together, and the sum is written into the addition memory 1212 . Third line: The input image data and the data in the addition memory 1212 are added together, and the sum is written into the addition memory 1212 . · Fourth line: The input image data and the data in the addition memory 1212 are added together, and the sum is written into the addition memory 1212 and simultaneously output to the sub-scanning average value calculation unit 1211 .

[0101] At this time, since only data within the threshold range is input in the threshold determination, the following data including the foreign matter adhering to the white guide plate 70 shown in FIG. 1st line: 6th pixel 2nd line: 7th pixel 3rd line: 7th pixel 4th line: 8th pixel

[0102] The sub-scanning pixel adder 1210 treats the input data for the line of the target pixel as "0". The sub-scanning pixel adder 1210 writes the values ​​in the addition memory 1212 that have been added up to the previous line back into the addition memory 1212. As a result, the addition results are 800 digit@8 bit for the 1st to 5th pixels, 600 digit@8 bit for the 6th pixel, 400 digit@8 bit for the 7th pixel, and 600 digit@8 bit for the 8th pixel, as shown in FIG.

[0103] (2) Counting the number of lines within the threshold range Furthermore, the sub-scanning pixel summing unit 1210 counts, for each pixel, the image data within the threshold range input from the threshold determination unit 1209. As shown in Fig. 11, the first to fifth pixels are not affected by dirt, so the counter is "4", and the sixth to eighth pixels include a line in which data outside the threshold range has been removed, so the pixel counters are "3", "2", and "3", respectively. The sub-scanning pixel summing unit 1210 also outputs the result of this pixel counter to the sub-scanning average value calculation unit 1211.

[0104] 11, the sub-scanning average calculation unit 1211 divides the addition result for each pixel by the line counter number using the addition result and the line counter input from the sub-scanning average calculation unit 1211. The sub-scanning average calculation unit 1211 writes this division result in the shading data memory 1208.

[0105] In this way, by setting a threshold value that can be used to determine in advance that the data is not affected by foreign matter, and generating shading data by excluding data outside the threshold range, it is possible to eliminate the effects of dirt or scratches on the white guide plate 70.

[0106] Thus, according to this embodiment, even if the white guide plate 70, which is a flat density reference member, has foreign matter such as dirt or scratches, each pixel can read data of the white guide plate 70 in an area not affected by the foreign matter by moving the white guide plate 70 in the main scanning direction. Also, since the foreign matter removal and shading data generation unit 1207 generates shading data using data of an area not affected by the foreign matter, it is possible to generate shading data from which the influence of the foreign matter has been removed.

[0107] (Modification) Here, a modification of the first embodiment will be described.

[0108] Fig. 12 is a block diagram showing a modified example of the functional configuration of the image processing circuit 120 according to the first embodiment. As shown in Fig. 12, the image processing unit (front stage) 1201 includes a black correction unit 1213 between an image rearrangement unit 1204 and a white correction unit 1205.

[0109] The image rearrangement unit 1204 outputs the rearranged image data to the black correction unit 1213. The black correction unit 1213 performs black correction processing to subtract output data of the sensor chip 112 of the second reading unit 101 when there is no input light amount, and outputs the result to the white correction unit 1205.

[0110] By performing foreign matter removal in this manner after removing the black correction data, the precision of foreign matter removal can be improved.

[0111] (Second embodiment) Next, a second embodiment will be described.

[0112] The second embodiment differs from the first embodiment in that foreign matter removal and shading data generation are performed using data from the top several lines with high output values ​​while reading the white guide plate 70. In the following explanation of the second embodiment, explanations of the same parts as in the first embodiment will be omitted, and only differences from the first embodiment will be explained.

[0113] Fig. 13 is a block diagram showing the functional configuration of the foreign substance removal and shading data generation unit 1207 according to the second embodiment. As shown in Fig. 13, the foreign substance removal and shading data generation unit 1207 includes a size comparison unit 1214, a line memory 1215, a sub-scanning pixel addition unit 1210, and a sub-scanning average value calculation unit 1211.

[0114] The size comparison unit 1214 presets an arbitrary number of lines for the image data read while the white guide plate 70 is moving in the main scanning direction. Then, the size comparison unit 1214 stores in the line memory 1215 the data of an arbitrary number of lines with high numerical values ​​of the read result for each pixel in the image data during the period when the white guide plate 70 is read.

[0115] At this time, the size comparison unit 1214 compares the smallest output value for each pixel among an arbitrary number of lines with the input image data by size judgment, and if the numerical value of the input image data is higher, it replaces it with the smallest output value of the line memory 1215 of the target pixel. Note that the size comparison unit 1214 does not replace image data outside a preset threshold range. Note that the threshold is set taking into consideration unevenness of the white guide plate 70, the illuminance of the light source unit 111 of the second reading unit 101, and the aging fluctuation of the sensor chip 112 of the second reading unit 101.

[0116] A sub-scanning average value calculation unit 1211 calculates the average value of each pixel using a preset arbitrary number of lines, generates shading data, and stores the image data in a shading data memory 1208 .

[0117] In this embodiment, the reason why the sub-scanning average value calculation unit 1211 sets an arbitrary number of lines is that, since there are generally density unevenness in the white guide plate 70, which also serves as a density reference member, it is desirable to average the lines obtained in multiple areas.

[0118] Next, a specific operation of foreign substance removal and shading data generation in the foreign substance removal and shading data generation unit 1207 will be described. Fig. 14 is a diagram showing a specific operation of foreign substance removal and shading data generation. The example shown in Fig. 14 is an example in which the number of lines in the line memory 1215 is two.

[0119] As shown in FIG. 14, the result of reading the white guide plate 70 is input to a size comparison unit 1214 of the foreign substance removal and shading data generation unit 1207 .

[0120] The magnitude comparison unit 1214 of the foreign substance removal and shading data generation unit 1207 performs the following operations.

[0121] First line: The data of the first line is written to the line memory 1215 as the data with the lowest output value. Second line: The data for the second line is written to the line memory 1215. At this time, the data with the lowest output value in the line memory 1215 is compared with the data for the second line for each pixel, and the data with the lowest output value is swapped with the data with the second lowest output value. 3rd line: The data of the 3rd line is compared with the data with the lowest output value in the line memory 1215, and if the data of the 3rd line is higher, it is swapped with the data with the lowest output value in the line memory 1215 of the target pixel. When swapping, the numerical values ​​of the data with the second lowest output are compared with the data of the 3rd line, and the lower numerical value is set as the data with the lowest output value, and the higher numerical value is set as the data with the second lowest output value. In the example shown in Fig. 14, at the 6th pixel, the numerical value of the data with the first lowest output value in the line memory 1215 is 100 digits, while the output value of the data on the 3rd line is 200 digits, so swapping of the numerical values ​​in the line memory 1215 occurs. 4th line: The data of the 4th line is compared with the data with the lowest output value in the line memory 1215, and if the data of the 4th line is higher, it is swapped with the data with the lowest output value in the line memory 1215 of the target pixel. When swapping, the numerical values ​​of the data with the second lowest output are compared with the data of the 4th line, and the lower numerical value is set as the data with the lowest output value, and the higher numerical value is set as the data with the second lowest output value. In the example shown in Fig. 14, the numerical value of the data with the first lowest output value in the line memory 1215 at the 7th pixel is 100 digits, while the output value of the data on the 3rd line is 200 digits, so swapping of the numerical values ​​in the line memory 1215 occurs.

[0122] Then, the sub-scanning pixel summing unit 1210 adds two lines of data in the line memory 1215 and outputs the sum to the sub-scanning average value calculating unit 1211 .

[0123] A sub-scanning average value calculation unit 1211 divides the data added by the sub-scanning pixel addition unit 1210 by “2” to generate shading data, and writes it into the shading data memory 1208 .

[0124] The reason for generating the shading data using the average value of a plurality of lines in this manner is to eliminate the influence of unevenness in the white guide plate 70.

[0125] Thus, according to this embodiment, by using the data of the top several lines with high output values ​​while reading the white guide plate 70, which is a flat density reference member, it is possible to generate shading data that is less susceptible to the influence of foreign matter such as dirt. According to this embodiment, the numerical value used for division when generating shading data is common for each pixel compared to the first embodiment, so the circuit is simpler.

[0126] (Third embodiment) Next, a third embodiment will be described.

[0127] The third embodiment differs from the first and second embodiments in that, when multiple lines of the white guide plate 70 are read, the current result of reading the white guide plate 70 is compared with past results, and if data outside the threshold range is input for the past results, it is determined to be a foreign object. In the following explanation of the third embodiment, explanations of the same parts as the first or second embodiment will be omitted, and only differences from the first or second embodiment will be explained.

[0128] Fig. 15 is a block diagram showing the functional configuration of a foreign substance removal and shading data generation unit 1207 according to the third embodiment. As shown in Fig. 15, the foreign substance removal and shading data generation unit 1207 includes a threshold determination unit 1209, a sub-scanning pixel addition unit 1210, an addition memory 1212, and a sub-scanning average value calculation unit 1211.

[0129] The foreign matter removal and shading data generation unit 1207 executes the following process on the image data read while the white guide plate 70 is moving in the main scanning direction.

[0130] First line: The determination by the threshold determination unit 1209 is skipped, and image data is input to the sub-scanning pixel addition unit 1210 , and the data is written to the addition memory 1212 . Second line: The data written in the addition memory 1212 for the first line is input to a sub-scanning average value calculation unit 1211. The sub-scanning average value calculation unit 1211 divides the input image data by the current number of input lines (1 line in this case) and inputs the result to a threshold determination unit 1209.

[0131] The threshold determination unit 1209 compares the reading result of the white guide plate 70 with a preset threshold, and if the reading result of the white guide plate 70 is within the threshold range, it inputs the reading result of the white guide plate 70 to the sub-scanning pixel addition unit 1210. On the other hand, the threshold determination unit 1209 compares the reading result of the white guide plate 70 with a preset threshold, and if the reading result of the white guide plate 70 is outside the threshold range, it inputs the average value input from the sub-scanning average value calculation unit 1211 to the sub-scanning pixel addition unit 1210. In other words, if there is no dirt, the reading result of the density reference member is used, and if it is determined that there is dirt, the average value input from the sub-scanning average value calculation is used.

[0132] The threshold value is set to a value for the purpose of determining the presence or absence of a foreign object, taking into consideration unevenness of the white guide plate 70, the illuminance of the light source unit 111 of the second reading unit 101, and the fluctuation over time of the sensor chip 112 of the second reading unit 101.

[0133] Thereafter, the foreign substance removal and shading data generation unit 1207 repeats the operation for the second line.

[0134] When the reading period of the white guide plate 70 ends, the sub-scanning average value calculation unit 1211 writes the output of the sub-scanning average value calculation unit 1211 into the shading data memory 1208 .

[0135] In the above description, it has been described that the data of the first line is written unconditionally to the addition memory 1212, but this is not limiting, and it is also possible to carry out processing by the threshold determination unit 1209 on the assumption that there is dust on the first line, and if it is outside the threshold range, to set the central value of the threshold, etc. In this way, when averaging multiple lines to generate shading data, it is possible to reduce errors during averaging more effectively than if dust data were mixed in.

[0136] Next, a specific operation of the foreign matter removal and shading data generation unit 1207 will be described. Fig. 16 is a diagram showing a specific operation of the foreign matter removal and shading data generation. In the example shown in Fig. 16, Fig. 16(a) shows input data obtained by reading the white guide plate 70, and Fig. 16(b) shows a specific operation of the foreign matter removal and shading data generation. In the example shown in Fig. 16, attention is focused on the seventh pixel. The threshold value set in the threshold value determination unit 1209 has an upper limit of 210 digits and a lower limit of 190 digits.

[0137] The operation of foreign substance removal and shading data generation for the seventh pixel executed by the foreign substance removal and shading data generation unit 1207 will be described with reference to FIG.

[0138] First line: The input image data is 200 digits. Since this is the first line, there is no output from the sub-scanning average value calculation unit 1211, and therefore the output of the threshold determination unit 1209 is 200 digits. 200 digits are input to the addition memory 1212.

[0139] 2nd line: The input image data is 100 digits, and the output from the sub-scanning average value calculation unit 1211 is 200 digits (200 / 1=200) obtained by dividing the data in the addition memory 1212 for the first line by the number of lines read up to now. Because the input data is outside the threshold range (190 digits or more and 210 digits or less), the threshold determination unit 1209 inputs the output (200 digits) from the sub-scanning average value calculation unit 1211, rather than the input data, to the sub-scanning pixel addition unit 1210. The sub-scanning pixel addition unit 1210 adds up the current value (200 digits) of the addition memory 1212 and the value (200 digits) output by the threshold determination unit 1209 (400 digits) and writes the sum to the addition memory 1212 again.

[0140] Third line: The input image data is 100 digits, and the output from the sub-scanning average value calculation unit 1211 is 200 digits (400 / 2=200) obtained by dividing the data in the addition memory 1212 for the second line by the number of lines read up to now. Because the input data is outside the threshold range (190 digits or more and 210 digits or less), the threshold determination unit 1209 inputs the output (200 digits) from the sub-scanning average value calculation unit 1211, rather than the input data, to the sub-scanning pixel addition unit 1210. The sub-scanning pixel addition unit 1210 adds up the current value (400 digits) of the addition memory 1212 and the value (200 digits) output by the threshold determination unit 1209 (600 digits) and writes the sum to the addition memory 1212 again.

[0141] · 4th line: The input image data is 195 digits, and the output from the sub-scanning average value calculation unit 1211 is 200 digits (600 / 3=200) obtained by dividing the data in the addition memory 1212 for the 2nd line by the number of lines read up to now. The threshold determination unit 1209 inputs the input data (195 digits) to the sub-scanning pixel addition unit 1210 because the input data is within the threshold range (190 digits or more and 210 digits or less). The sub-scanning pixel addition unit 1210 adds up the current value (600 digits) of the addition memory 1212 and the value (195 digits) output by the 2-threshold determination unit 1209 (795 digits) and writes the sum to the addition memory 1212 again.

[0142] Thus, according to this embodiment, shading data can be generated in an area that is not affected by foreign matter such as dirt on the white guide plate 70, which is a flat density reference member. Compared to the first embodiment, the circuit is simpler because the value for division when generating shading data is common for each pixel. Also, no line counter is required. Furthermore, compared to the second embodiment, there is no need for a large-scale line memory, so the amount of memory can be reduced.

[0143] In each of the above embodiments, the image forming apparatus of the present invention is described as being applied to a multifunction device having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function. However, the image forming apparatus can be applied to any image forming apparatus, such as a copier, printer, scanner device, or facsimile device. [Explanation of symbols]

[0144] 1. Image forming device 2,4 Image reading device 5. Image forming section 70 Concentration standard material 111 Irradiation means 112 Reading means 1207 Shading Data Generation Unit [Prior art documents] [Patent documents]

[0145] [Patent Document 1] JP 2002-152510 A [Patent Document 2] JP 2009-284323 A

Claims

1. An illumination means for illuminating the document with light; A reading means for collecting and reading reflected light from a document; a flat-plate-shaped density reference member provided opposite the reading means; a moving means for moving the density reference member in a main scanning direction; a shading data generating unit that generates shading data in which foreign matter on the density reference member has been removed by executing a predetermined process on data read while the density reference member is being moved in the main scanning direction by the moving means; Equipped with the shading data generating unit extracts an arbitrary number of lines having high output values ​​while reading the density reference member, and generates shading data.

1. An image reading apparatus comprising:

2. An illumination means for irradiating a document with light; A reading means for collecting and reading reflected light from a document; a flat-plate-shaped density reference member provided opposite the reading means; a moving means for moving the density reference member in a main scanning direction; a shading data generating unit that generates shading data in which foreign matter on the density reference member has been removed by executing a predetermined process on data read while the density reference member is being moved in the main scanning direction by the moving means; Equipped with the shading data generating unit sets a threshold value that can be used to determine that the density reference member is not affected by a foreign object, and when multiple lines of the density reference member are read, the shading data generating unit compares the current result of reading the density reference member with a past result, and determines that the density reference member is a foreign object when data outside the range of the preset threshold value is input with respect to the past result.

1. An image reading apparatus comprising:

3. a black correction unit that performs black correction processing by subtracting a sensor output when there is no input light amount, at a stage preceding the shading data generation unit; The shading data generating unit performs a process for removing an influence of a foreign substance on the density reference member from the data after the black correction process by the black correction unit.

3. The image reading device according to claim 1, wherein:

4. the shading data generating unit sets a threshold value that can be used to determine that the image data is not affected by a foreign object, and excludes image data of the density reference member that is outside a range of the preset threshold value.

4. The image reading device according to claim 1, wherein the image reading device is a digital camera.

5. the moving means moves the density reference member in a main scanning direction by 2 mm or more; 5. The image reading apparatus according to claim 1, wherein the image reading apparatus comprises: a first scanning unit;

6. An image reading device according to any one of claims 1 to 5; An image forming unit; An image forming apparatus comprising:

Images