JP4487813B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image on a sheet while conveying the sheet on which an image is recorded.

  There has been proposed an image reading apparatus that reads an image of a sheet on which the sheet on which the image is recorded is conveyed. In this type of image reading apparatus, a contact glass as a paper placement member is provided on a paper conveyance path, and the paper conveyed by the conveyance means is placed (supported) and light can be transmitted. An imaging element (photoelectric conversion element) such as a CCD (Charge Coupled Device) is provided on the contact glass side with respect to the conveyance path, and the reflected light of the light irradiated on the paper by the light source is passed through the contact glass. Detected and converted to an electrical signal. For example, an image processing unit provided in the image reading apparatus is connected to the image sensor, and captured image data of a sheet image is generated based on an electrical signal from the image sensor. The light emitted from the light source is irradiated onto the paper on the contact glass, the reflected light is transmitted through the contact glass, and the photoelectric conversion element detects the reflected light and converts it into an electrical signal. Based on this electrical signal, for example, The image processing unit performs image processing to generate captured image data and obtain a captured image of the image on the paper.

  Here, for example, if dirt such as dust or paper powder from the conveyance path adheres to the light receiving surface of the image sensor, a problem such as black streaks appearing in the captured image of the paper image occurs. Therefore, an invention for preventing the above dirt from adhering to the light receiving surface of the image sensor has been proposed, and is disclosed in Patent Document 1 below.

  In the invention disclosed in Patent Document 1, a shutter is provided in a housing that houses an image sensor, and when the image sensor does not read an image on a sheet, the image sensor is shielded from the conveyance path by the shutter. It has become so. Thus, dirt such as dust and paper powder from the conveyance path is prevented from adhering to the light receiving surface of the image sensor.

  However, the invention disclosed in Patent Document 1 has a configuration in which an image on a sheet is simply read by an image sensor, and therefore, read unevenness due to light amount unevenness of the light source and sensitivity unevenness of the image sensor occurs.

  For this reason, there has been proposed an invention provided with a color reference plate such as a white reference plate in order to correct this reading unevenness. In such an invention, the color reference plate is disposed on the paper placement side of the contact glass (more specifically, the image reading position on the paper conveyance path and on the optical axis of the image sensor), and the color of the color reference plate is the image sensor. To be read. The color reading on the color reference plate is performed prior to the image reading on the paper, and the image processing unit preliminarily creates captured image data of the color reference plate. Based on the captured image data of the color reference plate, the image processing unit detects the reading unevenness and creates a correction parameter corresponding to the reading unevenness. This correction parameter is used for correcting captured image data obtained by subsequent image reading of a sheet. The image processing unit corrects the captured image data of the paper image according to the correction parameter, thereby generating captured image data that can suppress the reading unevenness (hereinafter, shading correction). Accordingly, it is possible to obtain a captured image in which the reading unevenness is suppressed.

  As such a color reference plate for shading correction, there is one in which a document carry-in lid of the apparatus is applied, which is disclosed in Patent Document 2 below.

  In the invention disclosed in Patent Document 2, the document carry-in lid is provided on the opposite side of the image pickup element with respect to the conveyance path, and is rotated on the document conveyance path so that the image of the document. Can be arranged at an image reading position where the image sensor reads the image. A portion corresponding to the image reading position (portion facing the image sensor at the image reading position) of the document carry-in lid is a white surface that is used as a white reference for shading correction. When the image sensor reads the color of the white surface (white), the document carrying lid is rotated to move the white surface to the image reading position, and the color of the white surface is read by the image sensor.

  In addition to the invention disclosed in Patent Document 2, an invention including a color reference plate for shading correction has been proposed. An example of the invention is disclosed in Patent Document 3 below.

  In the invention disclosed in Patent Document 3, the white reference plate as the color reference plate can be moved in and out of the conveyance path of the paper, and the white reference plate appears on the conveyance path at the time of preparation for shading correction to create correction parameters for shading correction. On the other hand, the white reference plate is retracted from the conveyance path when reading the image of the paper. A cleaning unit is provided on the movement path of the white reference plate, and the cleaning unit adheres to the white reference plate by moving the white reference plate to rub against the white reference plate. It is designed to remove dirty dirt.

However, in the inventions disclosed in Patent Document 2 and Patent Document 3, reflected light from the white reference plate is detected by the image sensor through the contact glass when shading correction is prepared. When dirt such as paper dust adheres, the captured image of the white reference plate is affected by the stain of the contact glass even if the white reference plate is not dirty.
JP-A-5-143185 JP-A-6-14139 JP-A-6-62245

  In view of the above problems, the present invention prevents dirt from adhering to the light receiving surface of an image sensor when a paper image is not read, and allows shading without being affected by dirt on the paper placement member when preparing for shading correction. An object of the present invention is to provide an image reading apparatus capable of reading the color of a correction color reference plate.

An image reading apparatus according to claim 1 is housed in a housing in which an image reading window is formed, and an image sensor that reads an image of a sheet on which an image is recorded and conveyed, and the image sensor at the time of shading correction preparation. a color reference plate for shading correction to be taken by reads, the color reference plate is attached to shield the image reading window when the imaging element does not read any of the image and the color reference plate of the paper, said The color reference plate is moved from a position where the image reading window is shielded at the time of shading correction preparation so that the color reference plate is positioned at an image reading position of the paper that is downward on the optical axis of the image pickup element. And a shutter for maintaining the shielding state.

  In the image reading apparatus according to the first aspect of the present invention, since the paper placing member and the imaging element are provided across the predetermined conveyance path of the sheet on which the image is recorded, the imaging element is arranged on the conveyance path. It is possible to directly read an image of a sheet conveyed along the sheet placing member.

  Here, in this image forming apparatus, the shutter is provided on the image sensor side with respect to the transport path, and when the image sensor does not read the image on the paper, the image sensor is shielded from the transport path by the shutter. Therefore, when the image sensor does not read an image, even if the paper placement member is soiled with dust or paper powder, the shutter blocks dirt such as dust or paper dust, and thus dust is collected on the light receiving surface of the image sensor. And dirt such as paper dust can be prevented.

  In addition, this shutter is provided with a color reference plate for shading correction. The color reference plate is used when preparing shading correction (here, when preparing for shading correction, in order to create correction parameters for shading correction). When the image pickup device reads the color of the color reference plate in advance), the own color is directly read by the image pickup device. Therefore, at the time of shading correction preparation, even if the paper placement member is soiled with dust or paper dust, the image sensor can read the color of the color reference plate without being affected by the stain of the paper placement member. .

In preparation for shading correction, the shutter is moved so that the color reference plate is positioned at the image reading position of the sheet by the image sensor. Thereby, the image sensor can image the color reference plate with an appropriate focal length.

Further , since the shutter is moved so that the color reference plate is positioned at the image reading position, a dedicated movable member or movable means for moving the color reference plate is not required.

  In addition, the image sensor is kept shielded from the conveyance path by the shutter. Thereby, the chance that dirt, such as dust and paper dust, adheres to the light-receiving surface of an image sensor can be reduced.

An image reading apparatus according to a second aspect of the present invention is the image reading apparatus according to the first aspect , wherein the color reference plate moves from a position where the shutter shields the image reading window to a position where the image reading window is opened. A cleaning member for cleaning the surface of the color reference plate is provided in the middle of the path.

In the image reading apparatus according to the second aspect of the invention, since the cleaning member for cleaning the surface of the color reference plate is provided in the middle of the movement path of the color reference plate, the color reference plate is moved along with the movement of the shutter. The surface is cleaned by the cleaning member. As a result, even if dirt such as dust or paper dust adheres to the color reference plate, this dirt can be removed.

The image reading apparatus according to the invention of claim 3, in the invention of claim 1 or claim 2, wherein the periphery of the color reference plate on the surface of the imaging element opposite to the side of the shutter, painted black Or it is characterized by having been subjected to flocking.

In the image reading apparatus according to the third aspect of the invention, since the periphery of the color reference plate is subjected to black coating or flocking on the surface of the shutter facing the image sensor, the surface of the image sensor side Of these, irregular reflection of light can be suppressed at a portion where black coating or flocking is applied.

An image reading apparatus according to a fourth aspect of the present invention is the image reading apparatus according to any one of the first to third aspects, wherein the color reference plate is at least one of a white reference plate and a black reference plate. It is characterized by that.

In the image reading apparatus according to the invention described in claim 4 , since the color reference plate is at least one of white and black, the color reference plate of the image reading apparatus described in claim 4 is a color reference for shading correction. Ideal for use as a board.

The image reading apparatus according to the invention of claim 5 is the invention according to any one of claims 1 to 4, in the shutter, is resolution evaluation pattern for checking the reading resolution of said image sensor The color reference plate is juxtaposed.

In the image reading apparatus according to the fifth aspect of the present invention, since the resolution evaluation pattern for examining the reading resolution of the image sensor at the shutter is juxtaposed with the color reference plate, for example, when the shading correction preparation is performed, the image sensor is the color reference plate At the same time, the resolution evaluation pattern is read, and the reading resolution of the image sensor is checked based on the captured image of the resolution evaluation pattern. Thus, the image reading apparatus according to the sixth aspect can detect a problem such as dirt or paper dust adhering to the light receiving surface of the image sensor.

  As described above, the image reading apparatus according to the present invention prevents dirt from adhering to the light receiving surface of the image sensor when the image of the paper is not read, and also affects the influence of the paper placement member when preparing for shading correction. It has an excellent effect of being able to read the color of the color reference plate for shading correction without receiving the light.

  FIG. 1 schematically shows an image reading apparatus 10 according to an embodiment of the present invention. The image reading apparatus 10 reads an image on the paper 30 while conveying the paper 30 on which an image is recorded (see FIG. 3). Hereinafter, for convenience of explanation, in FIG. 1, the left side is the upstream side in the transport direction, and the right side is the downstream side in the transport direction.

  As shown in FIG. 1, the image reading apparatus 10 includes a box-shaped housing 18. The housing 18 has a pair of side walls 32 and 34 that face each other.

  A bottom wall 36 is integrally formed at the lower ends of the pair of side walls 32, 34. The bottom wall 36 is formed in a shape protruding somewhat downward. An approximately central portion in the left-right direction of the bottom wall 36 is opened, and this opened portion is an image reading window 20.

  A plate-like standing wall 37 that extends from the central portion to the vicinity of the conveyance path of the paper 30 is integrally formed on the bottom wall 36 on the right side (downstream in the conveyance direction) of the image reading window 20. ing. The standing wall 37 has a dimension (width dimension) corresponding to a width dimension of the shutter 26 described later in the width direction orthogonal to both the optical axis direction of the photoelectric conversion element 16 described later and the conveyance direction of the paper 30. Is formed.

  The lamp 12 is accommodated in the housing 18 as described above. The lamp 12 is disposed above the left end portion of the image reading window 20. The lamp 12 has a reflection plate 13 formed so as to wrap around the outer periphery from the lower left to the right substantially clockwise, and the lamp 12 extends in the lower right direction including the image reading window 20 side. Emits light. The lamp 12 is, for example, an Xe (xenon) lamp or a halogen lamp.

  A flat reflector 14 is housed inside the housing 18. The reflection plate 14 is disposed above the right end of the image reading window 20. The reflecting plate 14 corresponds to the lamp 12 and is disposed with the reflecting surface facing downward to the left. The reflecting plate 14 reflects the light emitted from the lamp 12 in the lower left direction including the image reading window 20 side. The reflecting plate 14 is, for example, an aluminum plate whose surface is polished.

  A photoelectric conversion element 16 as an imaging element is accommodated in the housing 18. The photoelectric conversion element 16 corresponds to the center position of the image reading window 20 and is disposed above the lamp 12 and the reflection plate 14. The photoelectric conversion element 16 is opposed to a back plate 28 as a sheet placing member described later, and its optical axis is directed downward. The photoelectric conversion element 16 reads an image of the sheet 30 conveyed along the back plate 28 by at least one of a roller pair 60 and a tension roller pair 61 which will be described later. Such a photoelectric conversion element 16 is, for example, a CCD (Charge Coupled Device) or a CMOS type line sensor, and detects light from below and converts it into an electric signal. The photoelectric conversion element 16 constitutes a photoelectric conversion means together with a contact reading type optical system (not shown) using a SELFOC lens or a reduction optical system (not shown) combining a plurality of lenses and mirrors.

  An image processing unit (not shown) is connected to the photoelectric conversion element 16, and the image processing unit generates captured image data of an image on the paper 30 based on an electrical signal from the photoelectric conversion element 16, and is used for shading correction. Correction parameters are created, or shading correction is performed on the captured image data of the image of the paper 30 in accordance with the correction parameters.

  A shutter 26 is provided below the housing 18. The shutter 26 has a shielding portion 26 </ b> B corresponding to the bottom wall 36 of the housing 18. The shielding part 26 </ b> B has a curved plate shape corresponding to the bottom wall 36, and can block the image reading window 20 of the housing 18 from the outside of the bottom wall 36.

  A shielding wall 26A corresponding to the side wall 32 of the housing 18 is formed integrally with the left end portion (end portion on the upstream side in the transport direction) of the shielding portion 26B. The shielding wall 26A is erected on the shielding part 26B along the outside of the side wall 32 (upstream in the transport direction) in a state where the shielding part 26B closes the image reading window 20.

  The shutter 26 having such a shape is connected to a swing-type solenoid and a linear-type solenoid attached to the housing 18, and as shown in FIG. It can be rotated around the axis (see arrow A), and can be moved in the vertical direction, that is, along the axial direction of the photoelectric conversion element 16 by the linear type solenoid (see arrow B). .

  Here, the shutter 26 indicated by a solid line in FIG. 4 is in the state shown in FIG. 1. In this state, the shutter 26 closes the inside of the housing 18 by closing the image reading window 20 of the housing 18. The photoelectric conversion element 16 is shielded from the conveyance path of the paper 30 without contacting the paper 30 being conveyed (away from the conveyance path of the paper 30) (hereinafter, the position of the shutter 26 in this state) Is called the shielding position).

  The shutter 26 indicated by a broken line at a position rotated in the arrow A direction (clockwise direction in FIG. 4) from the shielding position is in the state shown in FIG. 3, and in this state, the shutter 26 is in the housing 18. By opening the image reading window 20, the photoelectric conversion element 16 faces the conveyance path of the paper 30 directly, and the photoelectric conversion element 16 can directly read the image on the paper 30 (hereinafter, in this state). The position of the shutter 26 is called an open position).

  On the other hand, the shutter 26 indicated by a broken line at a position moved in the direction of arrow B (downward in FIG. 4) from the above-described shielding position is in the state shown in FIG. In this state, the shutter 26 is positioned at the image reading position on the optical axis of the photoelectric conversion element 16 with the central portion of the shielding portion 26B on the conveyance path of the paper 30 (hereinafter, the position of the shutter 26 in this state). Is referred to as the color reference plate imaging position). Here, when the shutter 26 moves from the shielding position to the color reference plate imaging position, and when the shutter 26 is located at the color reference plate imaging position, the shutter 26 cooperates with the standing wall 37 of the housing 18. The image reading window 20 is closed, the inside of the housing 18 is almost sealed, and the state where the photoelectric conversion element 16 is shielded from the conveyance path of the paper 30 is maintained.

  By devising the mechanism of the driving member or driving means of the shutter 26, the shutter 26 can be moved along the arrow A direction and the arrow B direction even with one actuator. Further, instead of moving the shutter 26 along the arrow A direction, the shutter 26 can be opened and closed along the horizontal direction (here, the conveyance direction of the paper 30), for example. In this case, two linear type solenoids may be used.

  In such a shutter 26, a white reference plate 27 as a color reference plate for shading correction is provided in the central portion of the shielding portion 26B. The white reference plate 27 is closely fixed to the surface on the photoelectric conversion element 16 side (the surface opposite to the conveyance path of the paper 30 in the thickness direction of the shielding portion 26B) at the center of the shielding portion 26B. The plate 27 is moved together with the shutter 26 as the shutter 26 moves between the closed position and the open position and between the closed position and the color reference plate imaging position. The white reference plate 27 has a white color as a reference color for shading correction, and the image reading position of the paper 30 by the photoelectric conversion element 16 is obtained by moving the shutter 26 to the color reference plate imaging position. In this image reading position, its own color is read by the photoelectric conversion element 16. The white reference plate 27 is, for example, a member such as a white plastic or a white painted metal plate. In addition, the white reference plate 27 may be a white film, or may be substituted for these members by directly applying white coating to the shutter 26. The white reference plate 27 is sufficient if the dimension in the sub-scanning direction (the arrow A direction of the shutter 26 shown in FIG. 4) is about 10 mm.

  Further, a back plate 28 is disposed on the opposite side of the conveyance path of the paper 30 from the photoelectric conversion element 16. The back plate 28 has a plate shape except for both end portions in the left-right direction (conveyance direction), and the paper 30 is placed on the upper surface thereof. The upper surface (sheet placement surface) of the back plate 28 is opposed to the light receiving surface of the photoelectric conversion element 16, so that it is emitted from the lamp 12 and directly or indirectly (via the reflector 14). The light irradiated on the paper 30 on the face plate 28 is reflected toward the photoelectric conversion element 16 side.

  In the image reading apparatus 10 as described above, the lamp 12, the photoelectric conversion element 16, and the solenoid (not shown) of the shutter 26 are connected to a control part (not shown), and this control part is the lamp 12, the photoelectric conversion element. 16 and each operation of the solenoid of the shutter 26 are controlled.

  Here, when the photoelectric conversion element 16 reads neither the image of the paper 30 nor the color of the white reference plate 27, the shutter 26 is moved to the shielding position as shown in FIG. It is moved (or located at the shielding position). Further, when the photoelectric conversion element 16 reads an image on the paper 30, the shutter 26 is moved to an open position as shown in FIG. 3 by a solenoid that receives an instruction from the control unit. In addition, when the photoelectric conversion element 16 reads the white reference plate 27 (hereinafter also simply referred to as preparation for shading correction), the shutter 26 causes the photoelectric conversion element 16 to be moved to the paper 30 by a solenoid that receives an instruction from the control unit. 2, the white reference plate 27 is moved to the color reference plate imaging position so that the white reference plate 27 is positioned at the image reading position as shown in FIG. The shutter 26 is in contact with the back plate 28 by supporting the back plate 28 with a spring or the like so that the back plate 28 can be retracted to the outside of the conveyance path of the paper 30 (the back plate 28 can be retracted from the conveyance path of the paper 30). At this time, the shutter 26 can push the back plate 28 away from the conveyance path of the paper 30 to accurately match the color reference plate image pickup position with the image reading position.

  In such an image reading apparatus 10, the creation of correction parameters for shading correction is executed prior to the image reading of the paper 30. When the correction parameter is created, the color of the white reference plate 27 is read, and the imaged image data of the white reference plate 27 is created in advance by the image processing unit. Based on the imaged image data of the white reference plate 27, the image processing unit detects reading unevenness due to unevenness in the light amount of the lamp 12 and sensitivity unevenness of the photoelectric conversion element 16, and the correction parameter corresponding to the reading unevenness is set. Created. This correction parameter is used for correcting captured image data obtained by subsequent image reading of the sheet 30. That is, the image processing unit corrects the captured image data of the image on the paper 30 according to the correction parameter, thereby generating captured image data that can suppress the reading unevenness. Accordingly, it is possible to obtain a captured image in which the reading unevenness is suppressed.

  The image reading apparatus 10 as described above is incorporated in, for example, the image forming apparatus 38 shown in FIG. 5 and is used as a quality inspection apparatus (image quality inspection apparatus) for images formed by the image forming unit 39 of the image forming apparatus 38. used. In the image forming apparatus 38, the image quality inspection by the image reading apparatus 10 is performed periodically, for example, once a day or at a timing designated by the user. The image reading apparatus 10 performs an image quality inspection by reading a test chart (image on the paper 30) for image quality inspection formed (printed) on the paper 30A. The image reading frequency of the image reading apparatus 10 used for such an application is relatively low.

  The image forming apparatus 38 described below is an apparatus for producing the above-described sheet 30 by forming a color image on the sheet 30A. The paper 30A is stored in a paper feed tray 58 of the image forming apparatus 38, and is fed out one by one by a pickup roller 59 provided on the paper 30A feeding side of the paper feed tray 58. The fed paper 30A is conveyed at a substantially constant speed along a conveyance path formed in the machine body by a predetermined number of roller pairs 60. Toner image formation for forming toner images of C (cyan), M (magenta), Y (yellow), and K (black) colors on the upper side of the conveyance path of the sheet 30A with an intermediate transfer belt 41 described later. The portions 40A, 40B, 40C, and 40D are arranged at substantially equal intervals along the circulation path (described later) of the intermediate transfer belt 41.

  The toner image forming units 40A, 40B, 40C, and 40D have the same configuration except for the color of the toner image to be formed, and the photosensitive drum 42 is arranged so that the axis is orthogonal to the circulation direction of the intermediate transfer belt 41. It has. Around the photosensitive drum 42, a charger 44 for charging the photosensitive drum 42, and light (laser light in the present embodiment) is irradiated on the charged photosensitive drum 42 to electrostatic latent image A predetermined color toner is supplied to the electrostatic latent image forming portion on the photosensitive drum 42 and the electrostatic latent image is developed to form a predetermined color toner image on the photosensitive drum 42. A developing device 48 to be formed, a transfer device 50 disposed opposite to the photosensitive drum 42, a static eliminator (not shown) that neutralizes the photosensitive drum 42, a cleaner blade (not shown) for removing residual toner on the photosensitive drum 42, and Each of the cleaner brushes is arranged and configured.

  The toner image forming units 40A, 40B, 40C, and 40D form toner images of different colors on the peripheral surface of the photosensitive drum 42 by the charger 44, the light exposure device 46, and the developing unit 48, and then the toner images. Is transferred (primary transfer) onto an intermediate transfer belt 41 described later by the transfer unit 50. A series of processes of charging, exposure (electrostatic latent image formation), development (toner image formation), and transfer in each of the toner image forming units 40A, 40B, 40C, and 40D is performed in each of the toner image forming units 40A, 40B, 40C, and 40D. The execution timing is controlled so that the toner images formed in the above overlap on the intermediate transfer belt 41. As a result, a full-color toner image (for example, a toner image corresponding to the test chart) is formed on the intermediate transfer belt 41.

  The intermediate transfer belt 41 is provided below the toner image forming portions 40A, 40B, 40C, and 40D. The intermediate transfer belt 41 is an endless belt and circulates counterclockwise in FIG. The intermediate transfer belt 41 circulates while being held between the photosensitive drums 42 of the toner image forming units 40A, 40B, 40C, and 40D and the transfer units 50. On the intermediate transfer belt 41, the toner image forming unit is circulated. The toner images formed by 40A, 40B, 40C, and 40D are transferred and superimposed.

  The lower end portion of the circulation path of the intermediate transfer belt 41 intersects with the conveyance path (forward conveyance path) of the paper 30 </ b> A fed out from the paper feed tray 58 described above. A secondary transfer roller pair 62 is provided to sandwich the intermediate transfer belt 41 at a position where the circulation path of the intermediate transfer belt 41 and the conveyance path of the sheet 30A intersect, and the secondary transfer roller pair 62 is fed into itself. By pressing the intermediate transfer belt 41 against the sheet 30A, the color image on the intermediate transfer belt 41 is collectively transferred (secondary transfer) to the sheet 30A.

  A fixing unit 52 is disposed downstream of the secondary transfer roller pair 62 in the transport direction. The fixing unit 52 is provided with a heating roller 54 and a pressure endless belt 56 facing each other, and the toner image is sandwiched between the heating roller 54 and the pressure endless belt 56 by sandwiching the paper 30A onto which the toner image has been transferred. A fixing device of a heat fixing type that fixes the toner image on the paper 30A by heating the forming surface and pressurizing the paper 30A. The sheet 30A on which the toner image is fixed in this manner is the sheet 30 described above.

  The above-described image reading device 10 is disposed downstream of the fixing unit 52 in the transport direction. The image reading device 10 reads the image (the test chart) on the paper 30 in the body of the image forming device 38. In the image forming apparatus 38, the controller 64 determines the print quality of the paper 30 based on the captured image data of the test chart output from the image reading apparatus 10, and the image formation of the image forming apparatus 38 is performed according to the determination result. An instruction (image quality adjustment instruction) for appropriately performing processing is given to each of the toner image forming units 40A, 40B, 40C, and 40D.

  A tension roller pair 61 is provided on the downstream side in the transport direction of the image reading device 10, and the paper 30 feeding speed is somewhat higher than that of the roller pair 60. Thus, the tension roller pair 61 cooperates with the roller pair 60 immediately upstream in the transport direction to pull the paper 30 along the transport direction to remove the slack in the transport direction of the paper 30 and to remove the paper 30 from the back. It is conveyed along the face plate 28.

  A discharge tray 64 is provided on the downstream side of the tension roller pair 61 in the conveying direction, and the discharge tray 64 receives the paper 30 taken out from the body of the image forming apparatus 38.

  In the image forming apparatus 38 as described above, the toner image forming units 40A, 40B, 40C, and 40D, the intermediate transfer belt 41, the secondary transfer roller pair 62, and the fixing unit 52 form an image on the paper 30A. An image forming unit 39 for manufacturing 30 is configured.

  Next, the operation of the embodiment of the present invention will be described.

  The light exposure device 46 operates, and laser light is emitted from the light exposure device 46 in accordance with the image data for creating the test chart. The laser beam forms an image on the photosensitive drum 42 charged by the charger 44. That is, the laser beam emitted from the light exposure device 46 is scanned on the photosensitive drum 42, whereby an electrostatic latent image is formed on the photosensitive drum 42.

  Next, the developing device 48 supplies toner of a predetermined color to the electrostatic latent image forming portion on the photosensitive drum 42 and develops the electrostatic latent image, whereby a toner image of the predetermined color is formed on the photosensitive drum 42. Is formed.

  This toner image is transferred (primary transfer) onto the intermediate transfer belt 41 by the transfer device 50. In this case, as the intermediate transfer belt 41 moves along the circulation path, the toner images of the respective colors are sequentially superimposed on the intermediate transfer belt 41 to form a full-color toner image (a toner image corresponding to the above test chart). The

  Next, the toner image formed on the intermediate transfer belt 41 is taken out from the paper feed tray 58 and conveyed by the roller pair 60 at the pressure contact position of the secondary transfer roller pair 62 (position where the secondary transfer roller pair 62 is in pressure contact). Transfer (secondary transfer) to the sheet 30A. The sheet 30A on which the toner image is transferred from the intermediate transfer belt 41 is conveyed to the fixing unit 52 by the roller pair 60, and is transferred from the intermediate transfer belt 41 to the sheet 30A by the heating roller 54 and the pressure endless belt 56. The toner image is heat-fixed.

  The paper 30A that has been subjected to the above processing is used as the paper 30 on which an image (the above-described test chart) is formed, and is conveyed onto the back plate 28 of the image reading apparatus 10 by the roller pair 60. Here, the sheet 30 conveyed onto the back plate 28 is in a state where the image surface (the surface on which the test chart is formed) is directed upward (on the photoelectric conversion element 16 side).

  In the image reading apparatus 10, the back plate 28 and the photoelectric conversion element 16 are provided to face each other across the conveyance path of the paper 30, and the photoelectric conversion element 16 is located on the image reading position (on the conveyance path of the paper 30 and photoelectrically). When reading the test chart of the paper 30 conveyed to the position of the conversion element 16 on the optical axis), the shutter 26 is moved from the shield position shown in FIG. Is moved to the open position shown in FIG. As a result, the image reading window 20 of the housing 18 is opened, and there is nothing that blocks the photoelectric conversion element 16 from the conveyance path of the paper 30. For this reason, the photoelectric conversion element 16 can directly read the test chart of the paper 30 conveyed along the back plate 28 on this conveyance path.

  By the way, as a pre-process for imaging such a test chart, the image reading device 10 of the image forming device 38 creates a correction parameter for shading correction. When creating this correction parameter (when preparing for shading correction), the shutter 26 maintains a state in which the photoelectric conversion element 16 is shielded from the conveyance path of the paper 30 by a solenoid that receives an instruction from a control unit (not shown). However, the white reference plate 27 is moved from the shielding position to the color reference imaging position so that the white reference plate 27 is positioned at the image reading position of the paper 30 by the photoelectric conversion element 16. Thereby, the photoelectric conversion element 16 can image the white reference plate 27 at an appropriate focal length. Here, the image reading window 20 of the housing 18 is closed by the shutter 26 and the standing wall 37 of the bottom wall 36, and the interior of the housing 18 is almost sealed.

  When the white reference plate 27 is positioned at the image reading position, first, in order to obtain black reference data for shading correction, the color of the white reference plate 27 is read by the photoelectric conversion element 16 with the lamp 12 turned off. Next, to obtain white reference data for shading correction, the lamp 12 is turned on, and the color of the white reference plate 27 is read by the photoelectric conversion element 16 in this state. Here, even when the white reference plate 27 is positioned at the image reading position, the shielding state of the photoelectric conversion element 16 is maintained by the shutter 26.

  Here, in the image reading device 10, as described above, the surface of the shutter 26 (surface on the photoelectric conversion element 16 side) on which the white reference plate 27 for shading correction is provided on the photoelectric conversion element 16 side with respect to the conveyance path of the paper 30. ), The white reference plate 27 has its own color read directly by the photoelectric conversion element 16. In addition, even if the back plate 28 is contaminated with dust or paper dust, the shutter 26 blocks the dirt such as dust or paper dust to prevent the dust or paper dust from entering the housing 18. . Thereby, it is possible to prevent dirt such as dust and paper dust from adhering to the light receiving surface of the photoelectric conversion element 16. Therefore, the photoelectric conversion element 16 can read the color of the white reference plate 27 without being affected by the dirt on the back plate 28.

  On the other hand, when the photoelectric conversion element 16 of the image reading apparatus 10 does not read either the image of the paper 30 or the color of the white reference plate 27, the shutter 26 is opened or closed by a solenoid in response to an instruction from a control unit (not shown). The color reference plate is moved from the imaging position to the shielding position (or located at the shielding position). In a state where the shutter 26 is located at the shielding position, the image reading window 20 of the housing 18 is closed, and the photoelectric conversion element 16 is shielded from the conveyance path of the paper 30. That is, the shutter 26 blocks dirt such as dust and paper dust, and prevents the dust and paper dust from entering the housing 18. Thereby, it is possible to prevent dirt such as dust and paper dust from adhering to the light receiving surface of the photoelectric conversion element 16. Further, in this state, the shutter 26 does not come into contact with the paper 30 being conveyed, so that the conveyance of the paper 30 is not hindered.

  As described above, in the image reading device 10, when the image on the paper 30 is not read, the photoelectric conversion element 16 is shielded from the conveyance path of the paper 30 by the shutter 26. It is possible to reduce the chance that dirt such as dust and paper powder adheres to the surface.

  Further, as described above, in the image reading apparatus 10, the white reference plate 27 is positioned at the image reading position by moving the shutter 26 to the color reference plate imaging position. A dedicated movable member or movable means becomes unnecessary.

  Further, since the white reference plate 27 is attached to the shutter 26 so as to face the side opposite to the conveyance path of the paper 30 with respect to the movement path (the photoelectric conversion element 16 side with respect to the conveyance path of the paper 30), It is resistant to dirt such as paper dust, printing toner or ink (when the image forming apparatus is an inkjet apparatus).

  Note that the image reading apparatus 10 has black coating (for example, matte black coating) or flocking processing (for example, flocking paper) on at least a part of the surface of the shutter 26 on the photoelectric conversion element 16 side with respect to the movement path of the shutter 26. May be applied). In this case, it is possible to suppress irregular reflection of light at the portion on the photoelectric conversion element 16 side where black coating or flocking is applied. When these black coating or flocking processes are applied to the periphery of the white reference plate 27, the photoelectric conversion element 16 can read the color (white) of the white reference plate 27 more clearly, which is effective.

  In the image reading apparatus 10, the white reference plate 27 is applied as the color reference plate, but the present invention is not limited to this. When black is required as the reference color for shading correction (when it is necessary to obtain black reference data for shading correction), for example, the present invention replaces the white reference plate 27 with black as the color reference plate. A black reference plate may be applied, or both the white reference plate 27 and the black reference plate may be applied (for example, the black reference plate may be juxtaposed with the white reference plate 27). The color of the black reference plate may be read. As described above, when the black reference plate or both the white reference plate 27 and the black reference plate are applied as the color reference plate, the color reference plate for shading correction is used in the same manner as the white reference plate 27 of the present embodiment described above. Ideal for use as.

Further, in the image reading apparatus 10, when black is required as a reference color for shading correction, in addition to the above, the above black coating is applied at least around the white reference plate 27, and this black coating is applied. You may make it the photoelectric conversion element 16 read the color of a part. In this case, the shutter 26 is moved somewhat from the shielding position to the open position so that the black coating portion is positioned on the optical axis of the photoelectric conversion element 16, and the color of the black coating portion is changed by the photoelectric conversion element 16 to the lamp. What is necessary is just to make it read in 12 lighting states.
(Modification)
Hereinafter, a modified example of the image reading apparatus 10 according to the present embodiment will be described.

  In this modification, a brush 68 as a cleaning member is attached to the outside of the bottom wall 36 of the housing 18 and protrudes on the moving path of the shutter 26.

  As shown in FIGS. 6 and 7, the movement path of the white reference plate 27 (here, the path along which the white reference plate 27 moves when the shutter 26 is moved between the shielding position and the open position). A brush 68 is provided on the way. The brush 68 is attached to the outer side (lower surface side) of the bottom wall 36 on the upstream side of the image reading window 20 in the housing 18 and protrudes on the movement path of the white reference plate 27. The brush 68 cleans the surface of the white reference plate 27 by moving the white reference plate 27 at the position where the brush 68 is disposed and rubbing the surface of the white reference plate 27 against the brush 68.

  That is, when the white reference plate 27 moves the arrangement position of the brush 66 as the shutter 26 moves, the surface of the white reference plate 27 is rubbed against the brush 68. As a result, the surface of the white reference plate 27 is cleaned. Thereby, even if dirt such as dust or paper dust adheres to the white reference plate 27 for some reason, this dirt can be removed. In this way, the measure against contamination of the white reference plate 27 can be further enhanced.

  In the modification of the present invention, the brush 68 is applied as the cleaning member, but the modification of the present invention is not limited to this. In the modified example of the present invention, a cleaning blade may be applied as the cleaning member instead of the brush. In this case, the same effect as that of the modified example is achieved.

  The image reading apparatus 10 according to the embodiment of the present invention and the modifications thereof have been described above, but the present invention is not limited to this. For example, in the present invention, a resolution evaluation pattern such as a resolution evaluation chart for evaluating the resolution of the photoelectric conversion element 16 is disposed at the tip of the shutter 26 together with a color reference plate (for example, the above-described white reference plate 27). Also good. In this case, for example, when preparing for shading correction, the resolution evaluation pattern is moved at the image reading position by slightly moving the shutter 26 in accordance with an instruction from a control unit (not shown), and the photoelectric conversion element 16 and the color reference plate together with the resolution evaluation pattern. And the reading resolution of the photoelectric conversion element 16 is examined based on the captured image of the resolution evaluation pattern. As a result, the image reading apparatus 10 can detect such a problem that dirt such as dust or paper dust adheres to the light receiving surface of the photoelectric conversion element 16.

1 is a diagram schematically illustrating an image reading apparatus according to an embodiment of the present invention, and is a diagram in a state where an image reading window of a housing is closed by a shutter. FIG. 2 is a diagram corresponding to FIG. 1, illustrating a state in which the shutter is moved so that a color reference plate is positioned at an image reading position of a sheet by an image sensor. It is a figure corresponding to FIG. 1, and is a figure which shows the state by which the image reading window of the housing was opened by moving a shutter. It is a figure which shows the movement path | route of a shutter. 1 is a diagram showing an outline of an image forming apparatus incorporating an image reading device. It is a figure which shows the outline of the modification of an image reading apparatus. It is a principal part enlarged view of FIG.

Explanation of symbols

10 Image Reading Device 16 Photoelectric Conversion Element (Imaging Element)
26 Shutter 27 White reference plate (color reference plate)
28 Back plate (paper placement member)
30 Paper 68 Brush (cleaning member)

Claims (5)

An image sensor that reads an image of a paper that is housed in a housing in which an image reading window is formed and on which an image is recorded and conveyed;
A color reference plate for shading correction to be taken to read by the image sensor during the shading correction preparation,
Wherein the color reference plate is attached, from the position where the imaging device is shielded from the image reading window when not read any of the image and the color reference plate of the paper, to shield the image reading window during the shading correction preparation, A shutter that moves so that the color reference plate is positioned at an image reading position of the paper that is downward on the optical axis of the image sensor and maintains the shielding state of the image sensor;
An image reading apparatus comprising: A cleaning member for cleaning the surface of the color reference plate is provided in the middle of the movement path of the color reference plate from the position where the shutter shields the image reading window to the position where the image reading window is opened .
The image reading apparatus according to claim 1. The periphery of the color reference plate on the surface of the imaging element opposite to the side of the shutter, painted black or flocking is applied,
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. The color reference plate is at least one of a white reference plate and a black reference plate.
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. In the shutter, a resolution evaluation pattern for examining the reading resolution of the image sensor is juxtaposed with the color reference plate.
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus.

Images