JP2009143696A - Document carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document carrier capable of securely carrying a document, and reading the document with favorable precision. <P>SOLUTION: The document carrier is provided with a document thickness sensor 28 provided on the document carrying direction upstream of a reading part 17, a first displacement mechanism 155 to vary the interval between a first carrying roller 13 and a first follower roller 23, and a second displacement mechanism 156 to vary the interval between a second carrying roller 14 and a second follower roller 24 based on the thickness of the document 1. The second displacement mechanism 156 increases the interval between the second carrying roller 14 and the second follower roller 24 based on the thickness of the document 1 immediately before a tip of the document advances in between the second carrying roller 14 and the second follower roller 24, and decreases the interval between the second carrying roller 14 and the second follower roller 24 immediately after the tip of the document 1 advances in between the second carrying roller 14 and the second follower roller 24. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an original conveying apparatus, and more particularly to an original conveying apparatus that performs reading while conveying an original.

  Conventionally, in this type of document conveying device, the leading edge of the document collides with the conveying roller on the downstream side of the reading unit by raising the conveying roller disposed on the downstream side of the reading unit by the thickness of the document. An image misalignment caused by disturbing the conveyance of the document, that is, a so-called jitter is known (see, for example, Patent Document 1).

  FIG. 11 is a cross-sectional view illustrating a configuration of a conveyance roller of a reading unit of a conventional document conveyance device.

  As shown in FIG. 11, the conventional document conveying apparatus includes an image forming unit 212 including a light source, a lens, an image sensor, and the like, a contact glass 211 disposed above the image forming unit 212, and a contact glass 211. On the other hand, the first conveyance roller 203 and the first auxiliary roller 201 arranged on the upstream side in the conveyance direction of the document 205, and the second conveyance roller 204 and the first auxiliary roller 201 arranged on the downstream side in the conveyance direction of the document 205 with respect to the contact glass 211. The image forming unit 212 reads the document 205 conveyed by the first conveyance roller 203 and the second conveyance roller 204 at the position of the contact glass 211.

  The first transport roller 203 and the second transport roller 204 are rotatably supported by a side plate 206, and the side plate 206 is connected to a cover 207 attached to the document transport apparatus body via a pair of link members 208. It can be moved up and down while keeping parallel to the transport surface 213. A spring 209 is interposed between the side plate 206 and the cover 207, and the spring 209 urges the first conveyance roller 203 and the second conveyance roller 204 downward via the side plate 206. A reflection plate 210 that reflects light emitted from the light source of the image forming unit 212 is provided below the side plate 206.

In the conventional document conveying apparatus having such a configuration, the first conveying roller 203 and the first auxiliary roller 201 sandwich the document 205, and the first conveying roller 203 rises against the urging force of the spring 209. Then, the 2nd conveyance roller 204 and the reflecting plate 210 also raise. The leading edge of the document 205 passes between the raised second transport roller 204 and the second auxiliary roller 202. Further, after the trailing edge of the document 205 passes between the second conveyance roller 204 and the second auxiliary roller 202, the first conveyance roller 203, the second conveyance roller 204, and the reflection plate 210 are urged by the spring 209. And descend to return to the original state.
Japanese Patent No. 3471553

  However, in the conventional document conveying apparatus as described above, the first conveying roller 203, the first auxiliary roller 201, and the document 205 that are generated when the first conveying roller 203 and the first auxiliary roller 201 sandwich the document 205. Due to the compression deformation, the amount of rise of the second conveyance roller 204 becomes smaller than the thickness of the original 205, so that the original 205 enters between the second conveyance roller 204 and the second auxiliary roller 202. The impact of the leading end of the document 205 colliding with the second transport roller 204 and the second auxiliary roller 202 cannot be sufficiently mitigated, and a reading defect such as jitter may occur. .

  On the other hand, in order to completely prevent the front end of the document 205 from colliding with the second conveyance roller 204, the first conveyance roller 203 and the second conveyance roller 204 are not arranged in parallel to the conveyance surface 213, When the second transport roller 204 is offset upward so that the second transport roller 204 is slightly above the first transport roller 203 in consideration of the amount of compression deformation in advance, the document 205 is placed in the first transport roller 203. And the first auxiliary roller 201, the gap between the second conveying roller 204 and the second auxiliary roller 202 becomes equal to the thickness of the original 205, and the leading edge of the original 205 is connected to the second conveying roller 204 and the first auxiliary roller 201. 2, it is possible to prevent collision with the auxiliary roller 202, but in this case, the pressing force between the second conveying roller 204 and the second auxiliary roller 202 is reduced, and the trailing edge of the document 205 is conveyed to the first conveying roller. After passing through the over La 203, conveyance failure there is a problem that occurs conveying force of the second conveying roller 204 becomes insufficient.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a document conveying device that can reliably convey a document and can accurately read the document.

  An original conveying apparatus according to the present invention includes a reading unit that reads an original, a first conveyance roller pair that is provided upstream of the reading unit in the original conveying direction, and that conveys the original while sandwiching the original. And a second conveying roller pair that sandwiches the original and conveys the original, and is provided upstream of the reading means in the original conveying direction. A thickness measuring means for measuring the thickness of the original, a first gap changing means for changing a gap between the first conveying roller pair based on the thickness of the original measured by the thickness measuring means, and the thickness And a second gap changing means for changing the gap between the second conveying roller pair based on the thickness of the original measured by the measuring means.

  With this configuration, when the trailing edge of the original is separated from the first conveying roller pair by the first gap changing unit based on the thickness of the original measured by the thickness measuring unit, the gap between the first conveying roller pair Is changed to be equal to the thickness of the original, and when the leading edge of the original enters the second conveyance roller pair by the second gap changing means, the second conveyance is changed. By changing the gap between the second conveying roller pair so that the gap between the roller pair becomes equal to the thickness of the document, the impact when the leading edge of the document enters the second conveying roller pair and the trailing edge of the document are the first. It is possible to alleviate the impact when separating from the pair of transport rollers and prevent the occurrence of reading defects such as jitter, and the document can always be transported by the second transport roller pair or the first transport roller pair. Surely carry the manuscript It is possible, it can be read accurately document.

  Further, in the document conveying apparatus according to the present invention, the second gap changing unit sets the thickness of the document measured by the thickness measuring unit immediately before the leading edge of the document enters the second conveying roller pair. Based on this, the gap between the second conveyance roller pair is increased, and the gap between the second conveyance roller pair is decreased immediately after the leading edge of the document enters the second conveyance roller pair. To do.

  With this configuration, the impact when the leading edge of the document enters the second transport roller pair is reduced by increasing the gap between the second transport roller pair before the leading edge of the document enters the second transport roller pair. Therefore, it is possible to prevent reading failure such as jitter.

  In the document conveying device according to the present invention, the thickness of the document measured by the thickness measuring unit immediately before the first gap changing unit releases the trailing edge of the document from the first conveying roller pair. The gap between the first conveyance roller pair is increased, and the gap between the first conveyance roller pair is decreased immediately after the trailing edge of the original is separated from the first conveyance roller pair. Features.

  With this configuration, before the trailing edge of the document is separated from the first conveying roller pair, the impact when the trailing edge of the document is separated from the first conveying roller pair is increased by increasing the gap between the first conveying roller pair. It can be mitigated to prevent the occurrence of poor reading such as jitter.

  Further, in the document conveying apparatus according to the present invention, the thickness of the document measured by the thickness measuring unit immediately before the second gap changing unit enters the leading edge of the document into the second conveying roller pair. The gap between the second conveyance roller pair is increased so as to be equal to the gap between the second conveyance roller pair, and the second conveyance immediately after the leading edge of the document enters the second conveyance roller pair. The gap of the roller pair is reduced, and the thickness of the original measured by the thickness measuring means immediately before the first gap changing means releases the trailing edge of the original from the first conveying roller pair. The gap between the first conveyance roller pair is increased so as to be equal to the gap between the first conveyance roller pair, and immediately after the trailing edge of the original is separated from the first conveyance roller pair, the first conveyance roller pair Characterized by reducing the gap of To.

  With this configuration, a gap equal to the thickness of the original is formed between the second conveying roller pair and the first conveying roller pair, and the original enters and leaves smoothly. It can be surely prevented from occurring.

  In the document conveying device according to the present invention, the reading unit includes a contact glass facing one surface of the document and a white plate facing the other surface of the document, and the thickness measuring unit And a third gap changing means for changing the gap between the contact glass and the white plate based on the measured thickness of the original.

  This configuration prevents the frictional resistance from increasing due to the gap between the contact glass and the white plate being narrower than the thickness of the original, and causes black or white streaks due to poor conveyance due to increased frictional resistance and scratches or dirt on the contact glass. It is possible to prevent the occurrence of reading failure such as.

  Further, the document conveying apparatus according to the present invention includes a first paper discharge path that maintains the conveying direction of the document conveyed by the second conveying roller pair, and the document conveyed by the second conveying roller pair. A paper discharge path switching means for switching between the second paper discharge path for changing the transport direction, wherein the paper discharge path switching means has a thickness of the original measured by the thickness measuring means equal to or greater than a reference value; In this case, the first paper discharge path is switched.

  With this configuration, when the thickness of the document is equal to or greater than the reference value, the document is guided to the first paper discharge path that maintains the document conveyance direction, and the document is guided to the second paper discharge path. Thus, it is possible to prevent a document conveyance failure and a reading failure such as jitter due to a change in the document conveyance direction.

  In the document conveying device according to the present invention, the first gap changing unit, the second gap changing unit, and the third gap changing unit are at least a motor, a cam mechanism, a spring, a worm mechanism, or a link mechanism. It is characterized by comprising a mechanism including one.

  With this configuration, the first gap changing means, the second gap changing means, and the third gap changing means can surely change the gap, alleviate the impact generated on the document, and read errors such as jitter. It can be prevented from occurring.

  Further, the document conveying apparatus according to the present invention is characterized in that the thickness measuring means is constituted by an ultrasonic reflection sensor or a laser reflection sensor.

  With this configuration, the thickness of the document can be accurately measured by the ultrasonic reflection sensor or the laser reflection sensor.

  Further, in the document conveying device according to the present invention, the thickness measuring unit is disposed in the vicinity of the first conveyance roller downstream in the document conveying direction, and is disposed in the vicinity of the middle portion in the width direction of the document. And a pressing member that presses the original against the reference surface so that the original does not float from a reference surface for measuring the thickness of the original.

  With this configuration, the thickness measuring means can measure the values when the document is not positioned on the reference surface near the center in the width direction of the document and when the document is positioned on the reference surface and pressed by the pressing member. By obtaining the difference, the thickness of the document can be measured reliably and systematically without being influenced by the size of the document.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to convey a document reliably, the document conveying apparatus which can read a document accurately can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of a document conveying device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a configuration around the reading unit of the document conveying device according to the embodiment of the present invention.

  First, the configuration will be described.

  As shown in FIGS. 1 and 2, the document conveying device 11 conveys the sheet-shaped document 1 to the reading unit 17, and sets a preset operation mode (rear discharge mode or front discharge mode) and the document 1. Depending on the thickness, the document 1 after reading is conveyed in the direction indicated by the arrow a and discharged to the first document discharge tray 26 at the rear (rear side) of the apparatus, or the document 1 after reading inversion is indicated by the arrow It is guided in the direction indicated by b and discharged to the second document discharge tray 12 in front of the apparatus (front side). Here, the front side of the apparatus (front side) is the side on which the display screen of the operation display unit 51 is facing, and the rear side of the apparatus (back side) is the side opposite to the direction of the display screen of the operation display unit 51, that is, This is the side of the first document discharge tray 26 that discharges the document 1 in the rear discharge mode.

  The document conveying device 11 includes an upper unit 20 and a lower unit 21 that are connected to each other by a connecting member such as a hinge (not shown). The upper unit 20 is connected to the lower unit 21 by a connecting member so as to be opened and closed in the vertical direction. On the upper part of the upper unit 20, an operation display unit 51 and a second document discharge tray 12 are mounted facing the front of the apparatus.

  The second document discharge tray 12 is composed of a metal wire formed in a comb shape, and is disposed on the upper unit 20 so as to rise obliquely from the rear of the apparatus toward the front of the apparatus, and is inverted and discharged. The prepared document 1 is stored so that it can be taken out from the front of the apparatus.

  The operation display unit 51 includes a key group (not shown) such as a start key, a numeric keypad, a clear / stop key, a function key, a Yes / No key, a cursor key, an initial setting key, a mode key, a liquid crystal touch panel, a speaker, and the like. By operation, setting of each operation mode, operation start instruction, and operation stop instruction can be performed. The operation display unit 51 displays the number of copies, device status, and the like, and appropriately displays function keys on the liquid crystal display panel according to the device status.

  The reading unit 17 includes a mirror (not shown), a light source, an imaging lens, a shading plate, a contact image sensor (CIS), and a contact glass 17a, and irradiates light on the document 1 inserted and conveyed from the front of the apparatus. The reflected light is imaged on a light receiving surface of a contact image sensor (CIS) through a mirror and an imaging lens, and the image surface is sequentially converted into an image signal (image data). Further, a white plate 16 is provided above the contact glass 17a that is in contact with the original 1 so as to press the original 1 against the contact glass 17a and serve as a white reference for the read image. Note that in the reading unit 17 using the contact image sensor, in order to obtain a focused high quality read image without jitter or the like, the conveying speed of the original 1 is kept constant, and the reading unit 17 and the original 1 are kept constant. In this embodiment, the gap between the contact glass 17a and the white plate 16 is increased or decreased according to the thickness of the document 1 as will be described later. It has become.

  A rotating shaft 29a is driven by a solenoid 65 (see FIG. 9) near the downstream of the second conveying roller 14, that is, between the second conveying roller 14 and the first document discharge tray 26, near the second conveying roller 14. A branch claw 29 that rotates about the center is provided. The document 1 after reading is guided to either the first document discharge tray 26 side or the second document discharge tray 12 side by the branching claw 29. Specifically, the branching claw 29 rotates in the direction indicated by an arrow j in the front paper discharge mode, and the second paper discharge formed by the curved paper discharge guide members 42 and 43 on the original 1 after reading. By guiding the path 159 and curving it to change its conveying direction, it is discharged to the second document discharge tray 12 side, and in the rear discharge mode, it is rotated in the direction indicated by the arrow i, and the document after reading 1 is guided to a first paper discharge path 158 formed by the straight paper discharge guide members 44 and 45 and discharged to the first document discharge tray 26 side without changing the transport direction. Further, even when the operation mode is the front discharge mode, the branching claw 29 moves in the direction indicated by the arrow i when the thickness of the document 1 measured by the document thickness sensor 28 is equal to or larger than the reference value. The document 1 is rotated to guide the document 1 to the first sheet discharge path 158 to be discharged to the first document discharge tray 26 side.

  The document thickness sensor 28 measures the thickness of the document 1 and is provided near the downstream of the first transport roller 13 and the first driven roller 23 in the document transport direction and near the center in the width direction of the document 1. . The document thickness sensor 28 includes a light emitting unit 28a that emits laser light, a light receiving unit 28b that receives reflected light of the laser light emitted from the light emitting unit 28a, and a reference plate 47, and emits light from the light emitting unit 28a. The difference between the time until the received light is reflected by the reference plate 47 and received by the light receiving unit 28b and the time until the light emitted from the light emitting unit 28a is reflected by the document 1 and received by the light receiving unit 28b. Based on this, the thickness of the document 1 is measured. The document thickness sensor 28 may be configured to measure the thickness of the document 1 based on the time from emitting an ultrasonic wave instead of laser light to receiving a reflected wave.

  The document thickness sensor 28 includes an elastic member 48 that presses the document 1 against the reference plate 47 so that the document 1 does not float from the reference plate 47. The elastic member 48 includes a fixing portion 48 a fixed to the document conveying device 11 and a pressing portion 48 b that moves by elastic deformation with respect to the fixing portion 48 a, and the pressing portion 48 b moves the document 1 to the reference plate 47. It is designed to be pressed. The pressing portion 48b is formed with an opening or notch through which light from the light emitting portion 28a passes.

  On the other hand, a document table 25 is disposed on the front upper surface of the lower unit 21, and a first document discharge tray 26 is protruded and attached to the rear rear surface of the lower unit 21. The document table 25 is used to place the document 1 with the reading surface facing downward, and guides the placed document 1 to a holding portion between the first transport roller 13 and the first driven roller 23. It is like that.

  A registration sensor 18, which is an optical reflection sensor, is disposed upstream of the reading unit 17. The registration sensor 18 detects the leading edge of the document 1 and turns on, and turns off after the trailing edge of the document 1 passes. The driving of the first conveyance roller 13 and the second conveyance roller 14 is stopped based on the timing when the registration sensor 18 detects the trailing edge of the document 1.

  In addition, a size detection sensor 22 and a document insertion detection sensor 27 are provided at the entrance of the document conveyance path of the document conveyance device 11, that is, in the vicinity of the upstream side of the first conveyance roller 13. In addition to detecting the size, the document insertion detection sensor 27 detects whether or not the document 1 is inserted into the conveyance path. When the size detection sensor 22 detects whether or not the document 1 is inserted into the conveyance path, the installation of the document insertion detection sensor 27 can be omitted.

  The first document discharge tray 26 is composed of a metal wire formed in a comb-teeth shape, is gently inclined so as to become higher toward the downstream in the transport direction, and extends from the second transport roller 14 in the extended state. The document 1 discharged rearward is stored.

  On the upstream side of the reading unit 17 in the conveyance direction, a first conveyance roller 13 and a first driven roller 23 that is driven in pressure contact with the first conveyance roller 13 are provided. Further, on the downstream side of the reading unit 17 in the conveyance direction, a second conveyance roller 14 and a second driven roller 24 that is driven in pressure contact with the second conveyance roller 14 are provided. The second transport rollers 14 are made of fluorine-based rubber, and a plurality of second transport rollers 14 are arranged in the axial direction of the second transport roller shaft 14a made of metal. The first transport roller 13 is configured in the same manner as the second transport roller 14. The second driven roller 24 is made of resin, and a plurality of second driven rollers 24 are arranged in the axial direction of the second driven roller shaft 24a made of metal. Further, the first driven roller 23 is configured in the same manner as the second driven roller 24. The first driven roller 23 is urged downward by springs 111 and 112 (see FIG. 3) and pressed against the first transport roller 13, and the second driven roller 24 is springs 131 and 132 (see FIG. 5). Is pressed downward against the second transport roller 14. In the present embodiment, foam rubber is not used for any of the first transport roller 13, the first driven roller 23, the second transport roller 14, and the second driven roller 24. It does not deform and the conveyance performance does not deteriorate.

  The first transport roller 13 and the second transport roller 14 are driven by a transport motor 67 (see FIG. 9) via drive transmission means having a timing belt. The first conveyance roller 13 is driven and controlled via an electromagnetic brake / clutch (not shown), and the electromagnetic brake / clutch is coupled by a document insertion detection signal to transmit the drive from the conveyance motor 67 and the document. The electromagnetic brake / clutch is disengaged from the time when the leading edge of 1 passes through the second conveying roller 14 until the trailing edge of the document 1 comes out of the document insertion detection sensor 27, whereby the preceding document is discharged from the document conveying device 11. The next document cannot enter the document transport device 11 until it is done. A conveyance guide member 46 that forms a conveyance path for the document 1 is provided between the document table 25 and the second conveyance roller 14 and the second driven roller 24.

  In addition, an image forming apparatus main body 19 is disposed below the document conveying device 11, and the image forming apparatus main body 19 includes a paper feeding unit 82 that stores transfer paper 78, 79, 80, and transfer paper 78, 79, 80 includes an image forming unit 81 for forming an image.

  The image forming unit 81 includes a drum-shaped photosensitive member 33, and the charger 33, the writing unit 30, the developing unit 32, the transfer charger 36, the separation charger 37, etc. in the order of the electrophotographic process centering on the photosensitive member 33. It has. The writing unit 30 constitutes a laser writing optical system including a laser output unit (comprising a laser diode, a polygon mirror, etc.), an imaging lens, a mirror, and the like. Further, a fixing roller 35, a pressure roller 34, paper discharge roller pairs 38 and 39, and paper discharge trays 40 and 41 are provided downstream of the transfer position of the photoconductor 33 in the transport direction.

  In the lower part of the image forming unit 81, a paper feed unit 82 for storing transfer papers 78, 79, 80 wound in a roll shape is provided. Removably with respect to each other. The transfer papers 78, 79, and 80 are cut according to the length of the original 1 by the cutters 76 and 77, and conveyed to the transfer position side of the photosensitive member 33 by the pair of paper feed rollers 71 to 75.

  As a result, one of the transfer sheets 78, 79, and 80 is selected and cut according to the length of the document 1 detected on the document transport device 11 side, and is photosensitive by the pair of feed rollers 71, 72, 73, 74, and 75. It is conveyed to the transfer position of the body 33. On the other hand, on the photoreceptor 33 that is rotationally driven in the sub-scanning direction, an electrostatic latent image is formed by the writing unit 30 and a toner image is formed by the developing unit 32. The cut transfer paper transported by the pair of paper feed rollers 71, 72, 73, 74, and 75 is transported by the registration roller pair 70 and a transport belt (not shown) while synchronizing with the front end of the toner image on the photoconductor 33. The toner image is transferred. The transfer paper after the transfer is subjected to fixing processing by the fixing roller 35 and the pressure roller 34 and then discharged onto the paper discharge trays 40 and 41 via the paper discharge roller pairs 38 and 39 according to the size of the transfer paper. .

  FIG. 3 is a perspective view showing a displacement mechanism of the first driven roller of the document conveying device according to the embodiment of the present invention. FIG. 4 is a top view showing a displacement mechanism of the first driven roller of the document conveying device according to the embodiment of the present invention.

  As shown in FIGS. 3 and 4, a first displacement mechanism 155 that is a displacement mechanism of the first driven roller 23 includes a first stepping motor 101, a worm gear 102 fixed to the output shaft of the first stepping motor 101, A worm wheel 103 that meshes with the worm gear 102 and rotates, a bearing 104 fixed to the worm wheel 103, a rotating shaft 108 fitted in the bearing 104, a bearing 105 fitted with the rotating shaft 108, and a bearing Arms 109 and 110 fixed to 104 and 105, respectively.

  Both ends of the first driven roller shaft 23a are loosely inserted into the arms 109 and 110, respectively, and the first driven roller shaft 23a is in the vertical direction, that is, close to the first conveying roller shaft 13a of the first conveying roller 13 and Holes 109a and 110a extending in the separating direction are formed.

  Further, the first displacement mechanism 155 includes side plates 106 and 107 into which the bearings 104 and 105 are rotatably fitted, and holes 109a formed in the arms 109 and 110 and into which both ends of the first driven roller shaft 23a are loosely inserted. 110a, and tension springs 111 and 112 that urge the first driven roller shaft 23a loosely inserted in the holes 109a and 110a downward, that is, in a direction close to the first transport roller shaft 13a of the first transport roller 13. I have. One end of the tension spring 111 is locked to one end of the first driven roller shaft 23 a, and the other end of the tension spring 111 is locked to a protruding locking portion 109 b formed on the arm 109. . On the other hand, one end of the tension spring 112 is locked to the other end portion of the first driven roller shaft 23 a, and the other end of the tension spring 112 is locked to a protruding locking portion 110 b formed on the arm 110. Has been. In FIG. 3, the side plates 106 and 107 are not shown.

  Therefore, the first driven roller 23 is elastically pressed against the first transport roller 13 by the tension springs 111 and 112.

  The first driven roller 23 rotates with the arms 109 and 110 around the rotation shaft 108 by driving the first stepping motor 101, so that the first driven roller 23 comes into pressure contact with the first conveyance roller 13 or the first conveyance roller 13. It is displaced in the vertical direction so that a gap is formed between them.

  The arm 109 is formed with an arc hole 109 c in an arc shape centered on the rotation shaft 108, and a stepped screw 113 inserted into the arc hole 109 c is screwed to the side plate 106. The arm 110 is provided with a detection piece 114a, and a first position sensor 114 formed in a U-shape so as to surround the detection piece 114a is provided in the vicinity of the detection piece 114a. The first position sensor 114 includes a light emitting unit and a light receiving unit (not shown), and the first position sensor 114 is provided on the arm 110 depending on whether or not the detection piece 114a is positioned in an optical path between the light emitting unit and the light receiving unit. The amount of movement from the position of the 1 driven roller 23 or the home position is optically detected. Here, the home position of the first driven roller 23 is a standby position of the first driven roller 23 in a state where the first driven roller 23 and the first transport roller 13 are in pressure contact with each other. As described above, the first displacement mechanism 155 changes the gap between the first conveying roller 13 and the first driven roller 23. Further, the gap between the first conveying roller 13 and the first driven roller 23 is changed based on the thickness of the document 1 measured by the document thickness sensor 28.

  FIG. 5 is a perspective view showing a displacement mechanism of the second driven roller of the document conveying device according to the embodiment of the present invention. FIG. 6 is a top view showing a displacement mechanism of the second driven roller of the document conveying device according to the embodiment of the present invention.

  As shown in FIGS. 5 and 6, the second displacement mechanism 156, which is a displacement mechanism of the second driven roller 24, includes a second stepping motor 121, a worm gear 122 fixed to the output shaft of the second stepping motor 121, A worm wheel 123 that rotates in mesh with the worm gear 122, a bearing 124 fixed to the worm wheel 123, a rotating shaft 128 fitted into the bearing 124, a bearing 125 into which the rotating shaft 128 is fitted, and a bearing Arms 129 and 130 fixed to 124 and 125, respectively.

  Both ends of the second driven roller shaft 24a are loosely inserted into the arms 129 and 130, respectively, and the second driven roller shaft 24a is in the vertical direction, that is, close to the second transport roller shaft 14a of the second transport roller 14 and Holes 129a and 130a extending in the separating direction are formed.

  Also, the second displacement mechanism 156 includes side plates 126 and 127 into which the bearings 124 and 125 are rotatably fitted, and holes 129a formed in the arms 129 and 130 and into both ends of the second driven roller shaft 24a. , 130a, and tension springs 131, 132 that urge the second driven roller shaft 24a loosely inserted into the holes 129a, 130a downward, that is, in a direction close to the second transport roller shaft 14a of the second transport roller 14. It has. One end of the tension spring 131 is locked to one end of the second driven roller shaft 24a, and the other end of the tension spring 131 is locked to a protruding locking portion 129b formed on the arm 129. . On the other hand, one end of the tension spring 132 is locked to the other end portion of the second driven roller shaft 24 a, and the other end of the tension spring 132 is locked to the protruding locking portion 130 b formed on the arm 130. Has been. In FIG. 5, the side plates 126 and 127 are not shown.

  For this reason, the second driven roller 24 is elastically pressed against the second conveying roller 14 by the tension springs 131 and 132.

  The second driven roller 24 rotates with the arms 129 and 130 about the rotation shaft 128 by driving the second stepping motor 121, so that the second driven roller 24 comes into pressure contact with the second conveyance roller 14 or the second conveyance roller 14. It is displaced in the vertical direction so that a gap is formed between them.

  The arm 129 is formed with an arc hole 129 c in an arc shape centered on the rotation shaft 128, and a stepped screw 133 inserted into the arc hole 129 c is screwed to the side plate 126. The arm 130 is provided with a detection piece 134a, and a second position sensor 134 formed in a U-shape so as to surround the detection piece 134a is provided in the vicinity of the detection piece 134a. The second position sensor 134 includes a light emitting unit and a light receiving unit (not shown), and is provided on the arms 129 and 130 depending on whether or not the detection piece 134a is positioned in an optical path between the light emitting unit and the light receiving unit. Further, the amount of movement from the position of the second driven roller 24 or the home position is optically detected. Here, the home position of the second driven roller 24 is a standby position of the second driven roller 24 in a state where the second driven roller 24 and the second transport roller 14 are in pressure contact with each other. As described above, the second displacement mechanism 156 changes the gap between the second transport roller 14 and the second driven roller 24. Further, the gap between the second conveying roller 14 and the second driven roller 24 is changed based on the thickness of the document 1 measured by the document thickness sensor 28.

  FIG. 7 is a perspective view showing a white plate displacement mechanism of the document conveying device according to the embodiment of the present invention. FIG. 8 is a top view showing a white plate displacement mechanism of the document feeder according to the embodiment of the present invention.

  As shown in FIGS. 7 and 8, the third displacement mechanism 157, which is the displacement mechanism of the white plate 16, includes a third stepping motor 141, a worm gear 142 fixed to the output shaft of the third stepping motor 141, and a worm gear 142. , The worm wheel 143 that rotates in mesh with the worm wheel, the bearing 144 that is fixed to the worm wheel 143, the rotating shaft 148 that is fitted into the bearing 144, the bearing 145 that is fitted with the rotating shaft 148, and the bearing 144, Arms 149 and 150 fixed to 145, respectively.

  Both ends of the white plate 16 are fixed to the arms 149 and 150, respectively. The third displacement mechanism 157 includes side plates 146 and 147 on which the bearings 144 and 145 are loosely fitted. In FIG. 7, the side plates 146 and 147 are not shown.

  For this reason, the white plate 16 is rotated in the vertical direction so that the distance between the white plate 16 and the contact glass 17a is changed by rotating with the arms 149 and 150 about the rotation shaft 148 by driving the third stepping motor 141. It is supposed to be displaced.

  In the arm 149, an arc hole 149c is formed in an arc shape centering on the rotation shaft 148, and a stepped screw 153 inserted into the arc hole 149c is screwed to the side plate 146. The arm 150 is provided with a detection piece 154a, and a third position sensor 154 formed in a U-shape so as to surround the detection piece 154a is disposed in the vicinity of the detection piece 154a. The third position sensor 154 includes a light emitting unit and a light receiving unit (not shown), and is fixed to the arms 149 and 150 depending on whether or not the detection piece 154a is positioned in an optical path between the light emitting unit and the light receiving unit. The amount of movement from the position of the white plate 16 or the home position is optically detected. Here, the home position of the white plate 16 is the white plate 16 in a state where the white plate 16 is in the lowered position and the smallest gap through which the document 1 can pass is formed between the white plate 16 and the contact glass 17a. This is the standby position. As described above, the third displacement mechanism 157 changes the gap between the contact glass 17a and the white plate 16. Further, the gap between the contact glass 17 a and the white plate 16 is changed based on the thickness of the document 1 measured by the document thickness sensor 28. Specifically, the gap between the contact glass 17 a and the white plate 16 is maintained within a range where the contact glass 17 a and the white plate 16 are not pressed against the document 1 and are within the depth of focus of the reading unit 17. It has become.

  The first displacement mechanism 155, the second displacement mechanism 156, and the third displacement mechanism 157 may be configured using at least one of other types of motors, springs, and worm mechanisms other than those described above. A link mechanism may be included.

  FIG. 9 is a block diagram showing a configuration of a control unit of the document conveying device according to the embodiment of the present invention.

  As shown in FIG. 9, the control unit 54 includes a mode setting signal from the operation display unit 51, a document insertion detection sensor 27, a registration sensor 18, a paper discharge sensor 49, a document thickness sensor 28, a first position sensor 114, and a second position sensor. Detection signals from the position sensor 134, the third position sensor 154, etc. are input, and a first stepping motor drive circuit 61 for driving the first stepping motor 101 and a second stepping motor 121 for driving the second stepping motor 121 are input based on these signals. 1 stepping motor drive circuit 62, a third stepping motor drive circuit 63 that drives the third stepping motor 141, and a solenoid drive circuit 64 that drives the solenoid 65, and outputs a drive command signal, CPU, memory (ROM, RAM, nonvolatile memory, etc.), input / output unit (I / O), interface unit, etc. There. The memory of the control unit 54 stores a reference value to be compared with the thickness of the document 1 when the branch claw 29 is switched.

  The control unit 54 also performs control of the synchronization signal generation circuit 55, drive control of the transport motor 67 via the transport motor drive circuit 66, flashing control of the light source 56, and the like. By such control, the document conveying apparatus according to the present embodiment performs each operation including a conveying operation and a reading operation of the document 1 at a preset speed.

  In the present embodiment, since the transport motor 67 is composed of a stepping motor, the control unit 54 responds to the drive step by multiplying, for example, the number of drive steps, that is, the number of pulses, by the transport distance per step. The transport distance can be easily acquired.

  The control unit 54 has a document insertion processing timer (not shown). This document insertion processing timer defines a delay time from when the document insertion detection sensor 27 detects a document until the start of document conveyance. In this embodiment, the delay time is set to 1 to 3 seconds. That is, the document insertion processing timer is provided to allow a margin for the document setting time. For example, when the document insertion detection sensor 27 detects the document 1 but the document 1 is not yet sufficiently inserted, This is provided to give the operator a correction time until an appropriate setting is made when the original 1 is clearly inserted obliquely. In this embodiment, the delay time by the document insertion processing timer is set to 1 to 3 seconds. However, it is desirable to set the delay time short or long depending on the skill level of the worker and the document size. In the present embodiment, adjustment is possible from the operation display unit 51.

  The synchronization signal generation circuit 55 supplies signals such as a clock and an address to the linear sensor 57, the analog processing circuit 58, the A / D conversion circuit 59, and the shading correction circuit 60.

  The analog processing circuit 58 has a function of adjusting the level of the analog image signal from the linear sensor 57 and performing sample hold and variable gain amplification (AGC).

  The A / D conversion circuit 59 converts an analog image signal into an 8-bit digital image signal. Note that an auto gain control (AGC) circuit (not shown) has a maximum value in the main scanning direction of the output of the A / D conversion circuit 59 when there is no document 1 between the contact glass 17a and the white plate 16. AGC amplification is controlled so as to be a predetermined value (for example, 220).

  The shading correction circuit 60 is mainly caused by shading correction, that is, distribution variation in the main scanning direction of the light amount of the light source 56 that illuminates the document 1 and characteristics from the CCD constituting the linear sensor 57 to the output of the A / D conversion circuit 59. The variation of the image signal in the scanning direction is corrected. In the shading correction processing, correction processing is performed for each pixel of the linear sensor 57 by the following formula: data after shading processing = (original image data / reference data) × 255. However, as the reference data, the output data of the A / D conversion circuit 59 when there is no document 1 between the contact glass 17a and the white plate 16 after AGC is adopted.

  Since AGC and shading processing are the same as those in the known prior art, detailed description is omitted. The AGC operation described above is performed, for example, when a main switch that activates the image forming apparatus main body 19 connected to the document conveying apparatus 11 is turned on.

  The driving force of the transport motor 67 is transmitted to the first transport roller 13 only when a feed clutch (not shown) is on, and is transmitted to the second transport roller 14 only when a paper discharge clutch (not shown) is on. ing.

  Next, the operation will be described.

  FIG. 10 is a flowchart showing the operation of the document conveying apparatus according to the embodiment of the present invention. The following processing relates to movement control of the first driven roller 23, the second driven roller 24, and the white plate 16 from when the inserted document 1 is detected by the document insertion detection sensor 27 until reading and discharging are completed. Explain.

  As shown in FIG. 10, first, the document thickness sensor 28 measures the thickness of the inserted document 1 (step S1).

  Next, the control unit 54 determines whether or not the measured value measured by the document thickness sensor 28 is equal to or greater than a reference value (step S2). When the measured value measured by the document thickness sensor 28 is equal to or greater than the reference value, the branching claw 29 is rotated by driving the solenoid 65 via the solenoid drive circuit 64 so that the document 1 is discharged from the first document. The paper discharge direction is switched so as to be guided to the tray 26 (step S3). If the measured value is less than the reference value, the process proceeds to step S4 without switching the paper discharge direction.

  Next, the control unit 54 drives the third stepping motor 141 via the third stepping motor drive circuit 63, whereby the gap between the contact glass 17a of the reading unit 17 and the white plate 16 is changed to the original in step S1. The white plate 16 is displaced upward so as to have a value corresponding to the thickness of the document 1 measured by the thickness sensor 28 (step S4). Specifically, the control unit 54 displaces the white plate 16 upward so that the gap between the contact glass 17 a and the white plate 16 is larger than the thickness of the document 1.

  Next, the control unit 54 reads the document 1 by the reading unit 17 (step S5).

  Next, the control unit 54 determines whether or not the front end of the document 1 is immediately before reaching the second conveyance roller 14 (step S6). Specifically, when the registration sensor 18 detects the leading edge of the document 1 by the number of steps corresponding to the distance from the registration sensor 18 to the second conveyance roller 14, the controller 54 drives the conveyance motor 67. It is determined that the front end of the document 1 is immediately before reaching the second conveyance roller 14.

  When the determination result in step S <b> 6 is “Yes”, the control unit 54 determines that the gap between the second conveyance roller 14 and the second driven roller 24 is larger than the thickness of the document 1. The second driven roller 24 that is paired with is displaced upward (step S7).

  Next, the control unit 54 transports the document 1 in a state where the gap between the second transport roller 14 and the second driven roller 24 is larger than the thickness of the document 1 by the process of step S7. It is determined whether or not a certain distance has been conveyed (step S8). If the determination result is "Yes", the second driven roller 24 is returned to the state before displacement, that is, the state in which it is pressed against the second conveyance roller 14. (Step S9). If the determination result in step S8 is “No”, the determination in step S8 is continued until the determination result becomes “Yes”. Here, the constant conveyance distance in step S8 is a slight conveyance distance, and it is determined that the document 1 has been conveyed by a certain distance immediately after the leading edge of the document 1 enters the second conveyance roller 14. Is done.

  Next, the control unit 54 determines whether or not the rear end of the document 1 is immediately before the first conveying roller 13 is released (step S10). Specifically, when the document insertion detection sensor 27 detects the trailing edge of the document 1 by the number of steps corresponding to the distance from the document insertion detection sensor 27 to the first conveyance roller 13, the conveyance motor 67 is driven. The control unit 54 determines that the trailing edge of the document 1 is immediately before the first conveyance roller 13 is removed.

  When the determination result in step S <b> 10 is “Yes”, the control unit 54 determines that the gap between the first transport roller 13 and the first driven roller 23 is larger than the thickness of the document 1. The first driven roller 23 paired with is displaced upward (step S11).

  Next, the control unit 54 transports the document 1 in a state where the gap between the first transport roller 13 and the first driven roller 23 is larger than the thickness of the document 1 by the process of step S11. It is determined whether or not a certain distance has been conveyed (step S12). If the determination result is "Yes", the first driven roller 23 is returned to the state before displacement, that is, the state in which it is pressed against the first conveyance roller 13. (Step S13). If the determination result in step S12 is “No”, the determination in step S12 is continued until the determination result becomes “Yes”. Here, the constant conveyance distance in step S12 is a slight conveyance distance, and the document 1 is conveyed by a certain distance in a state immediately after the rear end of the document 1 leaves the first conveyance roller 13. Determined.

  When the leading edge of the document 1 enters the nip portion between the first transport roller 13 and the first driven roller 23, the document 1 does not reach the contact glass 17a of the reading unit 17, and the document 1 is read. Therefore, it is not necessary to form a gap between the first conveying roller 13 and the first driven roller 23.

  As described above, the document conveying device according to the present embodiment is provided on the upstream side of the reading unit 17 in the document conveying direction, and measures the thickness of the document 1 and the document measured by the document thickness sensor 28. 1, a first displacement mechanism 155 that changes the gap between the first conveying roller 13 and the first driven roller 23, and the second conveying roller 14 based on the thickness of the original 1 measured by the original thickness sensor 28. And a second displacement mechanism 156 for changing the gap between the second driven roller 24 and the first transport roller 13 by the first displacement mechanism 155 based on the thickness of the document 1 measured by the document thickness sensor 28. When the trailing edge of the original 1 is separated from the first driven roller 23, the first conveying roller 13 and the first driven roller are set so that the gap between the first conveying roller 13 and the first driven roller 23 is equal to the thickness of the original 1. 3, and when the leading edge of the original 1 enters the second transport roller 14 and the second driven roller 24 by the second displacement mechanism 156, the second transport roller 14 and the second driven roller 24 By changing the gap between the second conveying roller 14 and the second driven roller 24 so that the gap becomes equal to the thickness of the original 1, the leading edge of the original 1 is moved into the second conveying roller 14 and the second driven roller 24. It is possible to reduce the impact and the impact when the trailing edge of the document 1 separates from the first transport roller 13 and the first driven roller 23, thereby preventing the occurrence of reading defects such as jitter. 14 and the second driven roller 24 or the first transport roller 13 and the first driven roller 23 can always transport the document 1, so that the document 1 can be transported reliably and the document 1 can be read with high accuracy. It can be.

  Further, in the document conveying apparatus according to the present embodiment, the document measured by the document thickness sensor 28 immediately before the second displacement mechanism 156 enters the second conveying roller 14 and the second driven roller 24 into the leading edge of the document 1. 1, the gap between the second conveying roller 14 and the second driven roller 24 is increased, and the second conveying roller immediately after the leading edge of the document 1 enters the second conveying roller 14 and the second driven roller 24. 14 and the second driven roller 24 are reduced, so that the second driven roller 24 is moved to the second transport roller 14 before the leading edge of the document 1 enters the nip portion between the second transport roller 14 and the second driven roller 24. The distance between the second conveying roller 14 and the second driven roller 24 is increased in the direction away from the original, and the impact when the leading edge of the document 1 enters the second conveying roller 14 and the second driven roller 24 is increased. Relieve Reading failure can be prevented from occurrence of jitter.

  In the document conveying apparatus according to the present embodiment, the document thickness sensor 28 measures the first displacement mechanism 155 immediately before the trailing edge of the document 1 is detached from the first conveying roller 13 and the first driven roller 23. Based on the thickness of the document 1, the gap between the first transport roller 13 and the first driven roller 23 is increased, and immediately after the trailing edge of the document 1 is detached from the first transport roller 13 and the first driven roller 23, the first Since the gap between the conveying roller 13 and the first driven roller 23 is reduced, the first driven roller 23 is moved to the first before the trailing edge of the document 1 is separated from the nip portion between the first conveying roller 13 and the first driven roller 23. By displacing in the direction away from the conveyance roller 13 and increasing the gap between the first conveyance roller 13 and the first driven roller 23, the trailing edge of the document 1 is separated from the first conveyance roller 13 and the first driven roller 23. Shock when Alleviating possible to prevent the reading failure occurs, such as jitter and.

  Further, in the document conveying apparatus according to the present embodiment, the document measured by the document thickness sensor 28 immediately before the second displacement mechanism 156 enters the second conveying roller 14 and the second driven roller 24 into the leading edge of the document 1. The gap between the second conveyance roller 14 and the second driven roller 24 is increased so that the thickness of 1 is equal to the gap between the second conveyance roller 14 and the second driven roller 24, and the second conveyance roller 14 and the second driven roller 24 are increased. Immediately after the leading edge of the document 1 enters, the gap between the second conveyance roller 14 and the second driven roller 24 is reduced, and the first displacement mechanism 155 causes the first document roller 1 to move from the first conveyance roller 13 and the first driven roller 23. The gap between the first conveyance roller 13 and the first driven roller 23 so that the thickness of the original 1 measured by the original thickness sensor 28 is equal to the gap between the first conveyance roller 13 and the first driven roller 23 immediately before the trailing edge is released. Immediately after the trailing edge of the document 1 is detached from the first conveying roller 13 and the first driven roller 23, the gap between the first conveying roller 13 and the first driven roller 23 is decreased. Since a gap equal to the thickness of the document 1 is formed between the second driven roller 24 and between the first conveying roller 13 and the first driven roller 23, the document 1 can be smoothly moved in and out, so that the impact is reduced. It is possible to reliably prevent occurrence of poor reading such as jitter.

  In the document conveying device according to the present embodiment, the reading unit 17 includes a contact glass 17 a that faces one surface of the document 1 and a white plate 16 that faces the other surface of the document 1. Since the third displacement mechanism 157 for changing the gap between the contact glass 17a and the white plate 16 based on the thickness of the document 1 measured by the document thickness sensor 28 is provided, the contact glass 17a and the white color are more white than the thickness of the document 1. An increase in frictional resistance due to a narrow gap between the plates 16 is prevented, and a conveyance failure due to an increase in frictional resistance and a reading failure such as black stripes or white stripes due to scratches or dirt on the contact glass 17a are prevented. be able to.

  The document conveying apparatus according to the present embodiment also includes a first paper discharge path 158 that maintains the conveying direction of the document 1 conveyed by the second conveying roller 14 and the second driven roller 24, and the second conveying roller 14. And a second paper discharge path 159 for changing the transport direction of the document 1 transported by the second driven roller 24, and the branch claw 29 is measured by the document thickness sensor 28. When the thickness of the original 1 is equal to or larger than the reference value, the first paper discharge path 158 is switched. Therefore, when the thickness of the original 1 is equal to or larger than the reference value, the first conveying direction of the original 1 is maintained. The document 1 is guided to the sheet discharge path 158, and the document 1 is guided to the second sheet discharge path 159 to change the conveyance direction of the document 1, thereby preventing the document conveyance failure and the reading failure such as jitter. can do.

  In the document conveying device according to the present embodiment, the first displacement mechanism 155, the second displacement mechanism 156, and the third displacement mechanism 157 include at least one of a motor, a cam mechanism, a spring, a worm mechanism, or a link mechanism. Therefore, the gap can be reliably changed by the first displacement mechanism 155, the second displacement mechanism 156, and the third displacement mechanism 157, and the impact generated on the document 1 can be mitigated to cause poor reading of jitter and the like. Can be prevented.

  In the document conveying apparatus according to the present embodiment, since the document thickness sensor 28 is composed of an ultrasonic reflection sensor or a laser reflection sensor, the thickness of the document 1 is accurately measured by the ultrasonic reflection sensor or the laser reflection sensor. Can be measured.

  Further, in the document conveying apparatus according to the present embodiment, the document thickness sensor 28 is disposed in the vicinity of the first conveying roller 13 and the first driven roller 23 in the document conveying direction downstream side, and the middle portion in the width direction of the document 1. The document thickness sensor 28 is disposed in the vicinity and has an elastic member 48 that presses the document 1 against the reference plate 47 so that the document 1 does not float from the reference plate 47 that measures the thickness of the document 1. In the vicinity of the center in the direction, the difference between the measured values when the document 1 is not positioned on the reference plate 47 and when the document 1 is positioned on the reference plate 47 and pressed by the elastic member 48 is obtained. The thickness of the document 1 can be reliably and systematically measured regardless of the size of the document 1.

  As described above, the document conveying device according to the present invention has an effect that the document can be reliably conveyed and the document can be read with high accuracy, and is useful as a document conveying device that performs reading while conveying the document. It is.

1 is a cross-sectional view illustrating a configuration of a document conveying device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a configuration around a reading unit of the document conveying device according to the embodiment of the invention. It is a perspective view which shows the displacement mechanism of the 1st driven roller of the document conveying apparatus which concerns on one embodiment of this invention. It is a top view showing a displacement mechanism of the first driven roller of the document conveying device according to the embodiment of the present invention. It is a perspective view which shows the displacement mechanism of the 2nd driven roller of the document conveying apparatus which concerns on one embodiment of this invention. It is a top view which shows the displacement mechanism of the 2nd driven roller of the document conveying apparatus which concerns on one embodiment of this invention. It is a perspective view which shows the displacement mechanism of the white board of the document conveying apparatus which concerns on one embodiment of this invention. FIG. 5 is a top view showing a white plate displacement mechanism of the document feeder according to the embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a control unit of the document conveying device according to the embodiment of the present invention. FIG. 6 is a flowchart showing the operation of the document conveying device according to the embodiment of the present invention. FIG. 6 is a side view showing a displacement mechanism of a conventional document feeder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Document 11 Document conveying apparatus 13 1st conveyance roller (1st conveyance roller pair)
14 Second transport roller (second transport roller pair)
16 White plate 17 Reading section (reading means)
17a Contact glass 18 Registration sensor 22 Size detection sensor 23 First driven roller (first conveying roller pair)
24 Second driven roller (second conveying roller pair)
26 first document discharge tray 27 document insertion detection sensor 28 document thickness sensor (thickness measuring means)
29 Branch claw (Discharge path switching means)
47 Reference plate 48 Elastic member (pressing member)
49 Paper discharge sensor 155 First displacement mechanism (first gap changing means)
156 Second displacement mechanism (second gap changing means)
157 Third displacement mechanism (third gap changing means)
158 First paper discharge path 159 Second paper discharge path

Claims (9)

Reading means for reading a document;
A first conveyance roller pair provided upstream of the reading unit in the document conveyance direction and configured to sandwich the document and convey the document;
A document conveying device comprising a second conveying roller pair provided downstream of the reading unit in the document conveying direction and configured to sandwich the document and convey the document;
A thickness measuring unit that is provided upstream of the reading unit in the document conveying direction and measures the thickness of the document;
First gap changing means for changing a gap between the first conveying roller pair based on the thickness of the document measured by the thickness measuring means;
An original conveying apparatus, comprising: a second gap changing unit that changes a gap between the second conveying roller pair based on the thickness of the original measured by the thickness measuring unit.   Based on the thickness of the original measured by the thickness measuring means immediately before the leading edge of the original enters the second conveying roller pair, the second gap changing means 2. The document conveying apparatus according to claim 1, wherein the gap is increased and the gap between the second conveying roller pair is decreased immediately after the leading edge of the document enters the second conveying roller pair.   Based on the thickness of the document measured by the thickness measuring unit immediately before the trailing edge of the document is separated from the first transport roller pair, the first gap changing unit is configured to use the first transport roller pair. 3. The gap between the first conveying roller pair is decreased immediately after the trailing edge of the original is separated from the first conveying roller pair. The document feeder described. The thickness of the original measured by the thickness measuring means is equal to the gap between the second conveying roller pair immediately before the second gap changing means enters the second conveying roller pair with the leading edge of the original. The gap between the second conveying roller pair is increased and the gap between the second conveying roller pair is decreased immediately after the leading edge of the document enters the second conveying roller pair.
The thickness of the original measured by the thickness measuring means is equal to the gap between the first conveying roller pair immediately before the first gap changing means releases the trailing edge of the original from the first conveying roller pair. The gap between the first conveying roller pair is increased so as to be equal, and the gap between the first conveying roller pair is decreased immediately after the trailing edge of the original is separated from the first conveying roller pair. The document feeder according to claim 3. The reading means includes a contact glass facing one surface of the document and a white plate facing the other surface of the document;
5. A third gap changing means for changing a gap between the contact glass and the white plate based on the thickness of the original measured by the thickness measuring means. The document conveying device according to any one of the above. A first paper discharge path that maintains the conveyance direction of the original conveyed by the second conveyance roller pair, and a second paper discharge path that changes the conveyance direction of the original conveyed by the second conveyance roller pair. And a paper discharge path switching means for switching between,
6. The discharge path switching means switches to the first discharge path when the thickness of the original measured by the thickness measurement means is equal to or greater than a reference value. The document conveying device according to any one of the above.   The first gap changing means, the second gap changing means, and the third gap changing means are configured by a mechanism including at least one of a motor, a cam mechanism, a spring, a worm mechanism, and a link mechanism. The document conveying device according to claim 1, wherein the document conveying device is one of the following.   The document conveying apparatus according to claim 1, wherein the thickness measuring unit includes an ultrasonic reflection sensor or a laser reflection sensor. The thickness measuring means is disposed in the vicinity of the downstream side in the document conveying direction of the first conveying roller pair, and is disposed in the vicinity of the middle portion in the width direction of the document.
The document according to any one of claims 1 to 8, further comprising a pressing member that presses the document against the reference surface so that the document does not float from a reference surface on which the thickness of the document is measured. Conveying device.

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