JP2009290801A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus that automatically changes a background color in reading an original document, includes a white surface for normal reading an original document and a white surface for shading, and can always obtain accurate shading data. <P>SOLUTION: An image reading section and a background body with a plurality of reading background surfaces are disposed with an original document carrying path sandwiched. A driving structure of the background body and a regulating body are provided on one side of the background body. The regulating body regulates an opposite distance between the background surface and the reading glass. Positioning surfaces and a curved guide surface for allowing the adjacent positioning surfaces to continue are formed on the peripheral surface of the regulating body. The driving mechanism is configured of a receiving body fixed on one side of the background body, a changeover tool for operating to rotate the background body by predetermined angle via the receiving body, and a solenoid for reciprocally operating the changeover tool. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus such as a copying machine, a facsimile machine, and a scanner machine, and more particularly to an improvement in a structure for changing a background surface of a background body facing a reading glass.

  In the image reading apparatus, it is known in Patent Document 1 that a background body having a plurality of background surfaces is driven to selectively select a background surface facing the reading glass. There, a white background surface is provided on the half of the peripheral surface of the background roller (background body), a black background surface is provided on the other half, and the background roller is rotated by a stepping motor so that the white and black background surfaces are provided. Can be directly opposed to the reading glass.

  An image reading apparatus having a similar background is also disclosed in Patent Document 2. In this case, a white background surface is provided on half of the plate surface of the flat plate-like background, and a black background surface is provided on the other half, and the background surface is opposed to the reading glass by sliding back and forth. Can be selected. In Patent Document 3, a white background surface is provided on the peripheral surface of a roller that always rotates when a document is read, and a belt-like black detection mark is provided on a part of the peripheral surface. Can be determined.

  In the image reading apparatus of the present invention, the background of the rectangular frame is rotated and the background color at the time of reading the document is automatically changed between white and black. This type of image reading apparatus is disclosed in Patent Document 4. It is known. There, a white reference surface, a black reference surface, and two types of reference surfaces set in an intermediate gradation from white to black are provided on each side surface of the reference plate having a rectangular cross section. When changing the background color, the background body is rotationally displaced about its axis, and any one of the background surfaces is positioned at the document reading position. When the background body is rotated, the entire scanner mechanism is slid and displaced outside the rotation locus of the background body in order to prevent the background body from coming into contact with the scanner mechanism. The reference plate is provided for acquiring shading correction data from each reference plane and correcting the linearity of the image signal using these data, not for performing skew correction.

JP 2003-348301 A (paragraph number 0022, FIG. 2) Japanese Patent Laying-Open No. 2003-219117 (paragraph number 0017, FIG. 3) JP 2005-136792 A (paragraph number 0037, FIG. 3) Japanese Patent Laid-Open No. 10-42111 (paragraph number 0022, FIG. 5)

  In the image reading apparatuses disclosed in Patent Literatures 1, 2, and 3, the background color can be automatically changed when the document is read. In addition, it is possible to eliminate the contamination of the white reference plate that cannot be avoided when the background color is changed manually. However, the same white surface is commonly used for both normal document reading and shading data reading. For this reason, it is unavoidable that the white surface is soiled by dirt and dust of the document passing through the sheet passing path. When a transparent plate glass is disposed between the white surface and the paper passing path, the white surface can be prevented from being stained as described above. However, the cost increases due to the arrangement of the plate glass, and the original reading position and the position of the white surface are separated by the thickness dimension of the plate glass, so that it is difficult to obtain accurate shading data.

  In the image reading apparatus of Patent Document 4, when the background body is rotated, it is necessary to slide and displace the entire scanner mechanism outside the rotation locus of the background body. Therefore, an extra time is required for properly using the background surface of the background body. It takes. Further, since the entire scanner mechanism is slid, the structure for sliding the scanner mechanism becomes large, and it is inevitable that the cost of the image reading apparatus increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus that can always acquire accurate shading data by automatically changing the background surface during document reading and using the background surface properly. An object of the present invention is to automatically change the background surface with a simpler structure, and to reduce the cost of the image reading apparatus accordingly.

  In the image reading apparatus of the present invention, an image reading unit and a background body having a plurality of background surfaces are arranged with a document conveyance path interposed therebetween. A driving structure for rotating the background body and a regulating body for defining a facing distance between the background surface and the reading glass are provided. A positioning surface and a curved guide surface that connects adjacent positioning surfaces are formed on the peripheral surface of the restricting body.

  Both ends of the restricting body are rotatably supported by the base frame. In addition, the regulating body is supported so as to be slidable in a direction approaching or moving away from the reading glass. The recording body is urged toward the reading glass by a spring.

  The drive structure includes a passive body arranged outside the reading range of the background body, a switching tool for rotating the background body by a predetermined angle via the passive body, and a solenoid for reciprocating the switching tool.

  A sensor for detecting the background surface facing the reading glass is provided outside the reading range of the background body.

  A plurality of background surfaces are provided on the outer surface of the background body. A protrusion is formed on the upstream side of each background surface in the document conveyance direction to restrict the document from contacting the background surface.

  The switching tool includes a holder that is fixed to the output rod of the solenoid, and an operation piece that is attached to the holder and rotates the switching tool. The operation piece is mounted on the holder in a state where it can swing between the driving position and the retracted position. The operation piece is biased toward the drive position by the return spring.

  In another image reading apparatus according to the present invention, an image reading unit and a background body are arranged with a document conveyance path interposed therebetween. The background body is composed of a pair of plate-like bodies each having a white background surface, and a drive structure for rotating the plate-like body is provided.

  The drive structure includes a forward / reverse motor and a gear that transmits the rotational power of the forward / reverse motor to a pair of plate-like bodies.

  In the image reading apparatus of the present invention, an image reading unit and a background body having a plurality of reading background surfaces are arranged across the document conveyance path, and the background body is provided with a plurality of background surfaces. In addition, when the background body driving structure and the regulating body are provided, and the posture of the background body is switched by the driving structure, the positioning surface provided on the circumferential surface of the regulating body is the facing distance between the background surface and the reading glass Can be specified to an appropriate amount.

  As described above, when the posture for the background body having a plurality of background surfaces is switched by the drive structure so that the reading glass faces the normal copy background surface, the shading correction background surface, and the like, The background surface can be automatically changed when reading a document. Also, by properly using the background surface, appropriate shading data can always be obtained and shading correction can be performed accurately. In the state where the posture of the background body is switched, the interval between the background surface and the reading glass can be strictly defined by the regulating body, so that color correction by each background surface can always be performed properly. Because the end of the positioning surface adjacent to the regulating body is made continuous with the curved guide surface, the rotation operation of the regulating body when the posture of the background body is switched by the drive structure is smooth with less resistance. be able to.

  According to the image reading apparatus that supports the regulating body in a freely rotatable manner with the base frame, the regulating body and the background can be slid in the direction away from the reading glass at the same time while rotating the regulating body and the background body. The body can be rotated and displaced without hindrance. Further, since the background body is urged toward the reading glass by a spring, a change in the distance between the rotation center of the background body and the reading glass at the time of rotation is absorbed by the spring, and the background body whose posture has been switched is appropriately set. It can be in close contact with the reading glass in its posture and maintain its state. Therefore, compared to the conventional device that required the entire scanner mechanism to slide out of the rotation trajectory of the background body, the posture switching structure is simplified and the cost required for manufacturing the image reading device is reduced accordingly. it can. There is also an advantage that the possibility of failure can be reduced by the simple structure.

  According to the drive structure composed of the passive body, the switching tool for rotating the background body via the passive body, and the solenoid for reciprocating the switching tool, the output rod of the solenoid only needs to reciprocate once. The posture can be switched from the background surface to the next background surface. Therefore, the background surface of the background body can be switched quickly and without excess or deficiency. There is also an advantage that the overall structure of the drive structure can be avoided and the cost can be reduced.

  If a sensor is provided outside the reading range of the background body so that the background surface that is currently facing the reading glass can be specified, it is necessary for the reading glass when performing various processes. A proper background can be properly faced. Further, it is possible to comfortably use the image reading apparatus by eliminating the user's effort as much as it is not necessary to confirm which background surface is facing the reading glass.

  According to the image reading apparatus in which a plurality of background surfaces are provided on the outer surface of the background body, and protrusions are formed on the upstream side in the document conveyance direction on each background surface, the document is received by the protrusions and the document contacts each background surface. Can be restricted. Therefore, it is possible to prevent the background surface from being soiled by dirt and dust adhering to the document, and to maintain the state of the background surface in a proper state over a long period of time.

  When the output rod is displaced according to the switching tool composed of the holder fixed to the output rod of the solenoid, the operation piece swingably supported by the holder, and the return spring for biasing the operation piece in the return direction The background body can be rotated only by the action of. Moreover, the switching tool after switching operation of the background body is returned by the spring force of the return spring. At that time, the operation piece gets over the passive body and returns to the original state. Therefore, it is sufficient to drive the solenoid only when changing the posture of the background body, and the power consumption of the image reading apparatus can be reduced accordingly. After the background body is switched, the background body is not moved by the return operation when the operation piece returns.

  In another image reading apparatus of the present invention, a background body composed of a pair of plate-like bodies is switched by a drive structure so that the background surface of the pair of plate-like bodies can be opposed directly to the reading glass. did. In this way, by changing the postures of the pair of plate-like bodies with the drive structure motor power, the background surface can be automatically changed when reading the document. Also, by properly using the background surface, appropriate shading data can always be obtained and shading correction can be performed accurately. It is advantageous in that it is not necessary to prepare a black background separately when both plates are placed in a posture that does not face the reading glass and the black void between the plates is used as a background surface. It is.

  If the drive structure is composed of a forward / reverse motor and a gear that transmits the rotational power of the forward / reverse motor, the background surface can be automatically and accurately changed simply by forward / reverse rotation of each plate with motor power. The For example, the entire drive structure can be simplified as compared with a drive structure using a solenoid as a drive source and a case where each plate-like body is rotationally driven by a dedicated motor.

(Embodiment) FIGS. 1 to 8 show an embodiment in which the image reading apparatus according to the present invention is applied to a multifunction machine having a copy function and a facsimile function. In FIG. 2, the multifunction peripheral includes an image reading device 1 that reads the contents of a document as image data, and an image recording device 2 that is disposed below the image reading device 1. The image reading apparatus 1 includes an operation panel 3 having a group of operation buttons, a presser cover 4, an automatic document feeder 5 provided inside the presser cover 4, and the like. The image recording apparatus 2 includes a paper feed cassette 7, a photoreceptor unit 8, a toner cartridge 9 for supplying toner to the unit 8, a paper transport structure 10 including a roller group and a transport guide. The recording paper delivered from the paper feed cassette 7 is transported along the paper transport structure 10, and after the image is recorded by the photosensitive unit 8, it is discharged.

  In FIG. 2, the automatic document feeder 5 includes a U-shaped document conveyance path 14 extending from a lower tray 12 to an upper document discharge portion 13. An introduction roller 15 is disposed at the start end of the document conveyance path 14, and a discharge roller 16 is disposed at the end. In the middle of the document transport path 14, a group of feed rollers 17, 18, 19, 20, 21, a first image reading unit (image reading unit) 22 that reads one document surface, and one document surface are read. A second image reading unit (image reading unit) 23 is arranged. Background bodies 24 and 24 each having a plurality of reading background surfaces are arranged at positions facing the image reading units 22 and 23 with the document conveyance path 14 therebetween.

  In FIG. 3, the first image reading unit 22 is configured by arranging a light source 27, an optical lens 28, and a solid-state imaging device (CCD device) 29 inside a frame 26. A reading window 30 facing the document conveyance path 14 is opened on the lower surface of the frame 26 and is covered with a transparent reading glass 31. The second image reading unit 23 is similarly configured.

  The background body 24 includes a frame body 34 having three side surfaces made of metal, background surfaces 35, 36, and 37 formed on the outer surfaces of the side surfaces of the frame body 34, and the longitudinal direction of the frame body 34. The support shaft 38 is fixed to both ends, and the restriction body 39 is provided at the base end of the support shaft 38. The background surfaces 35, 36, and 37 are formed by adhering strip-shaped sheet bodies to the respective side surfaces. In FIG. 1, the color state of the background surface 35 located on the lower surface of the frame body 34 is black, and the color state of the background surfaces 36 and 37 located on the side surface and the upper surface of the frame body 34 is white. The support shaft 38 and the regulating body 39 are provided outside the reading range of the image reading unit 22 together with a drive structure 43 described later. In document reading or skew correction, the background surfaces 35, 36, and 37 and the reading glass 31 are in a parallel relationship with each other, and the distance between the background surfaces 35, 36, and 37 and the reading glass 31 is constant. The accuracy of skew correction is improved. In a state where the background surfaces 35, 36, and 37 of the frame body 34 face the reading glass 31, rib-shaped protrusions 40 are formed on the upstream side of each side surface in the document transport direction. The projecting ends of the protrusions 40 protrude from the surfaces of the background surfaces 35, 36, and 37. Therefore, it is possible to prevent the read original from coming into contact with the surfaces of the background surfaces 35, 36, and 37.

  A pair of support shafts 38 are rotated by a bearing body 42 provided on a base frame 41 in order to rotate the background body 24 so that the required background surfaces 35, 36, and 37 face the image reading units 22 and 23. Support as possible. Further, the background body 24 can be rotated by the drive structure 43. In FIG. 1, both the support shafts 38 are guided by a slide groove 44 provided on the opposing wall of the base frame 41 so as to be slidable up and down. Further, the lower surface of the bearing body 42 is received by a compression coil-shaped spring 45, and the background body 24 is biased by the spring 45 in a direction approaching the reading glass 31. As a result, the background body 24 can slide in a direction toward or away from the reading glass 31 while rotating around the support shaft 38.

  The restricting body 39 is provided so that the background surfaces 35, 36, and 37 provided on the background body 24 and the reading glass 31 face each other in parallel, and the facing distance therebetween is constant. As shown in FIG. 3, the restricting body 39 is formed of a plate-like body in which each of the four corners of a square is rounded, and has four positioning surfaces 48 each including a linear side portion on its peripheral surface, and an adjacent positioning surface 48. A continuous arcuate guide surface 49 is formed. Each positioning surface 48 and the background surfaces 35, 36, and 37 described above are provided in parallel. In the state where each positioning surface 48 is in contact with the reading glass 31, the entire background body 24 is pushed toward the reading glass 31 by the spring 45, so that the background body 24 and the regulating body 39 rotate carelessly. There is no. Note that the positioning surface 48 may be in contact with other than the reading glass 31.

  The drive structure 43 includes a passive body 51 fixed to the protruding end of the left support shaft 38 as viewed in FIG. 4, a switching tool 52 that rotates the passive body 51 by 90 degrees, and a solenoid that reciprocates the switching tool 52. 53 and a return spring 54.

  The passive body 51 is integrally provided with a ratchet body 56 and four passive claws 57 formed on the outer surface of the ratchet body 56. The ratchet body 56 is formed as an analog that is slightly smaller than the regulating body 39 described above, and a V-shaped ratchet groove 58 is formed in each of the four sides. The rotation of the background body 24 is restricted by a ratchet groove 58 located on the lower surface side of the ratchet body 56 and a ratchet claw 59 that falls into the groove 58 and engages therewith. The ratchet pawl 59 is formed of a spring plate. The four passive claws 57 are formed by L-shaped rib-shaped projections and arranged in a cross shape (see FIG. 1). In order to improve the slip of the switching tool 52, the tip end portion and the outer corner portion of each passive claw 57 are each rounded into a partial arc shape.

  The switching tool 52 includes a holder 63 that is fixed to the upper end of the output rod 62 of the solenoid 53, an operation piece 64 that is attached to the holder 63 and pushes up the passive pawl 57, and moves the operation piece 64 toward the drive position. And a return spring 65 that biases. The holder 63 is integrally provided with a boss whose upper surface is rounded and a bracket 66 having a gate-like cross section projecting from the upper surface of the boss. The operation piece 64 is formed of a triangular plate-like body, and is disposed inside the aforementioned facing wall of the bracket 66 and supported by a pin 67 so as to be swingable in the vertical direction. That is, the operation piece 64 is mounted on the holder 63 so as to be able to swing between the drive position and the retracted position. A horizontal operation claw 68 for pushing up the passive claw 57 is formed at the protruding end of the operation piece 64 protruding from the lateral opening of the bracket 66.

  The return spring 65 is a torsion coil spring, one spring arm is hooked on the upper end surface of the operation piece 64, and the other spring arm is hooked on a spring receiving piece 69 provided on the peripheral surface of the boss. The operation piece 64 in the normal state is held at the standby position shown in FIG. 1 with its vertical side portion received by the vertical wall of the bracket 66. Therefore, the operation piece 64 can swing only in the direction in which the operation claw 68 swings upward from the standby position. The return spring 54 is formed of a tension spring, one end of which is hooked on a hook arm 70 provided on the boss of the holder 63, and the other end is hooked on a protrusion 71 provided on the base frame 41.

  In order to specify the background surfaces 35, 36, and 37 that face the reading glass 31, the detection disk 74 is fixed to the protruding end of the right support shaft 38 as viewed in FIG. A light emitting / receiving optical sensor (sensor) 75 is arranged. The optical sensor 75 outputs a light reception signal from the light receiving unit each time the background surfaces 35, 36, and 37 face the reading glass 31. The control device that has received the light reception signal can count the number of times the light reception signal has been received from the reference position, and can identify the background surfaces 35, 36, and 37 that face the reading glass 31.

  Next, the switching operation of the background body 24 by the drive structure 43 will be described. When normal copying is performed, the white background surface 37 is opposed to the reading glass 31 as shown in FIG. In this state, the white background surface 36 for shading correction is held outside the document conveyance path 14.

  When performing shading correction, the solenoid 53 is activated by the drive signal output from the control device, and the output rod 62 is advanced upward in FIG. Then, the operation claw 68 of the operation piece 64 comes into contact with the tip of the passive claw 57, and the passive body 51 is rotated clockwise toward FIG. At this time, the background body 24 and the regulation body 39 rotate in the same direction as the passive body 51.

  When the background body 24 and the regulation body 39 start to rotate clockwise, one end of the positioning surface 48 that has been in close contact with the reading glass 31 until then comes into contact with the reading glass 31 and eventually the partially arcuate guide surface 49. Comes into contact with the reading glass 31 (see FIG. 5). At this time, the background body 24 and the regulating body 39 slide in a direction away from the reading glass 31 while pressing and deforming the spring 45, and the spring 45 causes a change in the distance from the center of the support shaft 38 to the lower surface of the reading glass 31. Absorb. FIG. 5 shows a state in which the background body 24 has rotated 45 degrees or more after it has started to rotate clockwise. In this state, the tip of the passive claw 57 is in contact with the proximal end of the operation claw 68, and the ratchet claw 59 rides on the partial arc surface of the ratchet body 56. In FIG. 5, the advancing direction of the output rod 62 is indicated by an arrow a, and the rotation direction of the background body 24 is indicated by an arrow b.

  When the output rod 62 is further advanced upward from the state shown in FIG. 5 to rotate the passive body 51 and rotate 90 degrees after the background body 24 starts to rotate, a new positioning of the regulating body 39 as shown in FIG. The surface 48 contacts the reading glass 31. The position of the operation claw 68 at this time is shown by an imaginary line in FIG. In this state, the ratchet pawl 59 falls into the ratchet groove 58, and the ratchet body 56 is held in a state where it cannot rotate. At the same time, a light reception signal is output from the optical sensor 75 to the control device. At this time, the background 24 has a white background 36 for shading correction facing the reading glass 31 as shown in FIG. As a result, the white background 36 that is not soiled by the dirt or dust of the document is directly opposed to the image reading unit 22, and appropriate shading data can be acquired.

  Since it can be determined that the new background surface 36 faces the reading glass 31 by outputting a light reception signal from the optical sensor 75, the control device stops energizing the solenoid 53 at that time. Therefore, the output rod 62 is pulled back by the return spring 54 and descends. At this time, the operating claw 68 moving downward contacts the outer surface of the passive claw 57 positioned below the operating claw 68. The entire operation piece 64 received by the passive claw 57 swings counterclockwise around the pin 67 while resisting the elasticity of the return spring 65, as shown by a solid line in FIG. get over. The operation piece 64 that has passed over the passive claw 57 returns to the standby position by the elasticity of the return spring 65.

  When the above-described series of switching operations are performed again, the black background surface 35 can face the reading glass 31 as shown in FIG. In this state, since the entire background of the document is black, the skew correction of the document can be performed. Thereafter, the switching operation is repeated twice so that the white background surface 37 faces the reading glass 31 and normal copying can be performed. In the control device, each time the background surface 37 for normal copying faces the reading glass 31, the number of received light signals output from the optical sensor 75 is reset to 1, and the counter is returned to the initial state. It should be noted that which of the background surfaces 35, 36, and 37 is opposed to the reading glass 31 is basically automatically determined according to a program incorporated in the control device, but a start signal input by the user as necessary. Can be selected based on

  According to the drive structure 43 configured as described above, the posture of the background body 24 is automatically switched between normal copying, shading correction, and document skew correction. Appropriate background surfaces 35, 36, and 37 can be directly opposed to the reading glass 31. Accordingly, it is possible to eliminate the stains on the white background surfaces 36 and 37, which are inevitable when the background surfaces 35, 36, and 37 are manually changed.

  Further, since the white background surfaces 36 and 37 are selectively used for normal use and correction, it is possible to eliminate the correction background surface 36 from facing the document conveyance path 14 when performing normal image reading work. Therefore, the background surface 36 for shading correction is prevented from coming into contact with the document, and the background surface 36 is reliably prevented from being soiled by dirt or dust on the document, and the coloration state of the background surface 36 for shading correction is prevented. It is possible to maintain appropriate correction data for a long period of time and always obtain appropriate correction data. More accurate shading data can be obtained as compared with the case where the document conveyance path 14 and the background surface 36 for shading correction are separated by a plate glass.

  When the background body is formed by the frame body 34 having three side surfaces, and the white and black sheet bodies are respectively arranged on the outer surfaces of the respective side surfaces to form the background surfaces 35, 36, and 37, the sheet bodies are replaced. By doing so, the background surfaces 35, 36 and 37 can be updated. For example, the background surface 35, 36, and 37 can be updated more easily and the maintenance work can be reduced compared to the case where the dirt attached to the background surface 35, 36, and 37 is wiped off and removed. -37 coloration state can be made more favorable.

  9 to 13 show another embodiment of the background body 24 and the drive structure 43. FIG. In this case, the background body 24 is composed of a pair of plate-like bodies 81 and 82. Each of the plate-like bodies 81 and 82 is made of a plastic molded product, and white background surfaces 83 and 84 are provided on one side thereof. Support shafts 38 are provided at both ends of each plate-like body 81, 82, and these support shafts 38 are rotatably supported by bearing bodies 42 fixed to the base frame 41. A drive structure 43 is provided on one side of the base frame 41 in order to simultaneously swing the plate-like bodies 81 and 82 to switch between the use posture and the standby posture. The plate-like bodies 81 and 82 in the use position have white background surfaces 83 and 84 facing the reading glass 31 respectively, and the plate-like bodies 81 and 82 in the standby position have a background as shown in FIGS. The surfaces 83 and 84 hang down in an inclined posture.

  The drive structure 43 includes a forward / reverse motor 85, a worm shaft 86 and a worm gear 87 that convert rotational power of the forward / reverse motor 85 into rotational power around an axis parallel to the support shaft 38, and rotational power of the worm gear 87 in each plate shape. It comprises gears 88 and 89 that are transmitted to the bodies 81 and 82. The worm shaft 86 and the worm gear 87 also function as a speed reduction mechanism that reduces the rotational power of the forward / reverse rotation motor 85.

  In FIG. 11, the gears 88 and 89 are fixed to the support shaft 38 that supports the pair of plate-like bodies 81 and 82. The pair of plate-like bodies 81 and 82 reciprocate between the use position and the standby position by rotating in the opposite direction so as not to contact each other when the motor 85 rotates forward or reverse. Further, as shown in FIGS. 9 and 13, when one plate-like body 82 is in the use position facing the reading glass 31, the background surface 83 of the other plate-like body 81 in the standby position is obliquely downward. It has become. As shown in FIG. 10, a detection disk 74 is fixed to the other end of the support shaft 38 on which the final gear 88 is provided, and a light projecting / receiving light sensor (sensor) 75 with a rotation locus of the detection disk 74 in between. Is arranged.

  When normal copying is performed, as shown in FIG. 9, the background surface 84 of the plate-like body 82 located on the upstream side in the document transport direction is directly opposed to the reading glass 31. When performing shading correction, as shown in FIG. 13, the background surface 83 of the plate-like body 81 located on the downstream side in the document transport direction is directly opposed to the reading glass 31. Further, in the case of correcting the skew of the original, as shown in FIG. 12, the pair of plate-like bodies 81 and 82 are obliquely inclined to form a V shape. A black void between 82 is a background surface. The plate-like bodies 81 and 82 in this state are in the middle positions of the use posture and the standby posture.

  As described above, according to the background body in which the drive structure 43 can be reciprocally displaced between the use posture and the standby posture, the white background surfaces 83 and 84 are selectively used for normal use and correction, thereby performing normal image reading work. In this case, the correction background surface 83 can be prevented from facing the document conveyance path 14. Therefore, the background surface 83 for shading correction is prevented from coming into contact with the document, and the background surface 83 is reliably prevented from being stained by dirt or dust of the document, and the coloration state of the background surface 83 for shading correction is prevented. It is possible to maintain appropriate correction data for a long period of time and always obtain appropriate correction data. In addition, since the posture is switched by swinging and displacing the pair of plate-like bodies 81 and 82 in opposite directions, when performing normal copying, when performing shading correction, and when performing skew correction of a document. The background state can be switched quickly.

  In the above embodiment, the positioning surfaces 48 are provided at four locations on the peripheral surface of the restricting body 39, but the same number of positioning surfaces 48 as the background surfaces 35, 36, and 37 may be provided. The solenoid 53 may operate the switching tool 52 by an operation when the output rod 62 retracts toward the solenoid body. The sensor 75 does not need to be an optical sensor, and a sensor such as a proximity switch or a micro switch can be applied. The pair of plate-like bodies 81 and 82 can be driven by dedicated motors, respectively. If necessary, the pair of plate-like bodies 81 and 82 can be driven using a solenoid as a drive source.

  The image reading apparatus of the present invention can be applied to a copying machine, a facsimile machine, and a scanner machine in addition to a multifunction machine. In the above-described embodiment, the background body 24 is configured using the frame body 34 having three side faces as a base body. However, the background body 24 is not necessary, and the background body 24 is formed of a columnar body or a frame-shaped body having a polygonal cross section. can do. A normal background surface and a background surface for performing shading correction can be provided on a plurality of side surfaces, respectively. The plate-like bodies 81 and 82 do not need to be switched between the use posture and the standby posture by swinging, and can be switched between the use posture and the standby posture by being obliquely translated.

It is a longitudinal cross-sectional view which shows the drive structure of a background body. FIG. 2 is a layout explanatory diagram illustrating a schematic structure of a multifunction peripheral. It is a longitudinal cross-sectional view which shows the relationship structure of a background body and an image reading part. It is a vertical side view which shows the drive structure of a background body. It is a longitudinal cross-sectional view which shows the state in the middle of switching of a drive structure. It is a longitudinal cross-sectional view which shows the state which the switching of the drive structure was complete | finished. It is a longitudinal cross-sectional view which shows the state of a background body when switching of a drive structure is complete | finished. It is a longitudinal cross-sectional view of the state which switched the background body into another posture. It is a longitudinal cross-sectional view which shows another Example of a background body. FIG. 10 is a cross-sectional plan view showing a drive structure according to the background body of FIG. 9. FIG. 10 is a longitudinal sectional view of a drive structure according to the background body of FIG. 9. FIG. 10 is a longitudinal sectional view showing a state in which the background body of FIG. 9 is switched to another posture. FIG. 10 is a longitudinal sectional view showing a state in which the background body of FIG. 9 is switched to another posture.

Explanation of symbols

14 Document transport path 22 First image reading unit (image reading unit)
23 Second image reading unit (image reading unit)
24 background body 31 reading glass 35 background surface 36 background surface 37 background surface 39 regulating body 41 base frame 43 drive structure 44 slide groove 45 spring 48 positioning surface 49 guide surface

Claims (8)

An image reading unit and a background body having a plurality of background surfaces are arranged across the document conveyance path,
A drive structure for rotating the background body;
A regulating body is provided that defines an interval between the background surface and the reading glass;
An image reading apparatus in which a positioning surface and a curved guide surface that continues the adjacent positioning surfaces are formed on a peripheral surface of the restricting body. Both ends of the regulating body are rotatably supported by a base frame,
The regulating body is supported so as to be slidable in a direction approaching or moving away from the reading glass,
The image reading apparatus according to claim 1, wherein the regulating body is biased toward the reading glass by a spring. A passive body in which the driving structure is disposed outside the reading range of the background body;
A switching tool for rotating the background body by a predetermined angle via the passive body;
The image reading apparatus according to claim 1, further comprising a solenoid that reciprocates the switching tool.   The image reading apparatus according to claim 1, wherein a sensor for detecting the background surface facing the reading glass is provided outside the reading range of the background body. A plurality of background surfaces are provided on the outer surface of the background body,
5. The image reading apparatus according to claim 1, wherein a protrusion for restricting a document from contacting the background surface is formed on an upstream side of the background surface in the document conveyance direction. The switching tool is a holder fixed to the output rod of the solenoid;
An operation piece mounted on the holder and rotating the switching tool,
The operation piece is mounted on the holder in a state where it can swing between a driving position and a retracted position,
The image reading apparatus according to claim 3, wherein the operation piece is biased toward a driving position by a return spring. An image reading unit and a background body are arranged across the document conveyance path,
The background body is composed of a pair of plate bodies each having a white background surface,
An image reading apparatus provided with a drive structure for rotating the plate-like body. The drive structure is a forward / reverse motor,
The image reading apparatus according to claim 7, further comprising a gear that transmits rotational power of the forward / reverse rotation motor to the pair of plate-like bodies.

Images