JP2009263128A - Belt unit, image reading device, and image forming device - Google Patents

Abstract

An object of the present invention is to provide a belt unit capable of preventing the twisting of the belt with a simple configuration, and an image reading apparatus and an image forming apparatus provided with the belt unit.
A belt unit 75 according to the present invention includes a driving roller 77, a driven roller 79, and a driving roller 77 and an endless belt 81 wound around the driven roller 79. The driving roller 77 includes a belt. 81 has one drive shaft 85 provided over the entire width direction, and one and the other (a plurality of) roller portions 83a and 83b arranged coaxially with the drive shaft 85, and at least one roller portion is a belt. It is configured to rotate integrally with the drive shaft 85 only in the drive direction 81.
[Selection] Figure 1

Description

  The present invention relates to a belt unit that conveys an original or a recording medium, an image reading apparatus that reads an image while conveying the original by the belt unit, an image forming apparatus that includes the image reading apparatus, and a recording medium that includes the belt unit. The present invention relates to an image forming apparatus that forms an image while conveying the image.

  The prior art disclosed in Patent Document 1 discloses a belt unit in which an endless belt is wound around a driving roller and a driven roller. The drive roller of this belt unit has a configuration in which two drive shafts arranged on a coaxial line are connected via a one-way clutch, and a roller portion is fixed to each drive shaft. This prevents twisting of the belt due to variations in frictional force acting between the roller portion fixed to each drive shaft and the belt.

JP-A-6-332181

  However, since the two drive shafts are assembled via a one-way clutch, the configuration is complicated.

  SUMMARY An advantage of some aspects of the invention is to provide a belt unit that can prevent twisting of the belt with a simple configuration, and an image reading apparatus and an image forming apparatus including the belt unit.

  In order to solve the above-mentioned problems, the invention described in claim 1 includes a driving roller, a driven roller, and an endless belt wound around the driving roller and the driven roller. It has one drive shaft provided over the entire width direction and a plurality of roller portions arranged coaxially with the drive shaft, and at least one roller portion rotates integrally with the drive shaft only in the belt drive direction. It is characterized by.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, at least one roller portion is fixed to a drive shaft.

  According to a third aspect of the present invention, there is provided an image reading apparatus comprising the belt unit according to the first or second aspect, wherein an image is read while a document is conveyed by the belt unit.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the image reading apparatus according to the third aspect, wherein an image read by the image reading apparatus is formed on a recording medium.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising the belt unit according to the first or second aspect, wherein an image is formed while a recording medium is conveyed by the belt unit.

  According to the present invention, at least one of a plurality of roller portions arranged on one drive shaft is provided with a simple configuration so as to rotate integrally with the drive shaft only in the drive direction of the belt, and between the belt and each roller portion. Even if a biased tension is generated in the belt due to variations in the frictional force acting between them, the at least one roller portion rotates in the belt driving direction with respect to the driving shaft, so that twisting of the belt can be prevented.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing the drive roller of the belt unit according to the present embodiment. FIG. 2 (a) is a plan view of the belt unit according to the present embodiment, and FIG. ) Is a longitudinal sectional view of the belt unit according to the present embodiment, FIG. 3 is a block diagram showing a control configuration of the image forming apparatus according to the present embodiment, and FIG. 4 is an image according to the present embodiment. It is a longitudinal cross-sectional view which shows schematic structure of a forming apparatus.

  As shown in FIG. 4, an automatic document feeder (image reading device) 70 according to the present embodiment is mounted on an upper portion of an image forming apparatus 71, and is set with a document setting unit A for setting a document bundle. A separation feeding unit (sheet feeding device) B that separates and feeds each document from the bundle of documents S, a function of primarily abutting and aligning the fed document, and a function of drawing and transporting the document after alignment. The registration part C, a turn part D that turns the conveyed document and conveys the document surface toward the reading side (downward), and a first image that reads the surface image of the document from below the reading glass (contact glass) 21. 1 reading conveyance part E, 2nd reading conveyance part F which reads the back side image of the document after reading the front surface image, paper discharge part G which discharges the document whose front and back reading has been completed, and the document after the reading is completed Stack part H that holds and holds A pickup motor 101 (see FIG. 3) for driving the conveyance operation, a paper feed motor 102, a reading motor 103, a paper discharge motor 104, a bottom plate raising motor 105, and a controller 100 for controlling a series of these operations. Yes.

  The image forming apparatus 71 is a copier, and includes an image reading unit that reads an image of a document, an image forming unit that forms an image of the document read by the image reading unit on a sheet (recording medium), and a sheet of paper on the image forming unit. A paper feeding unit to be supplied and a paper discharge unit for discharging the paper on which the image forming unit has formed an image are provided.

  The document setting unit A is mounted on the document table 2 on which the document bundle S is placed, the document set filler 4 and the document set sensor 5 for detecting that the document is placed on the document table 2, and the document set table 1. Document length detection sensors 30 and 31 for detecting the size of the placed document. As the document length detection sensor, a reflection type sensor or an actuator type sensor that can be detected even with one document is used, and an outline of the length of the document in the conveyance direction is thereby determined. The document table 2 has a movable document table 3, and the movable document table 3 can be moved up and down in the directions a and b shown in the figure by a bottom plate raising motor 105, and the document has been set. When detected by the set filler 4 and the document set sensor 5, the bottom plate raising motor 105 is rotated forward to raise the movable document table 3 so that the uppermost surface of the document bundle contacts the pickup roller 7.

  The separation feeding unit B includes a pickup roller (calling member) 7 for calling the originals of the original bundle S, a separation roller 10 and a paper feed belt 9 for separating and conveying the called originals one by one toward the conveyance path. have. The pickup roller 7 is operated by the pickup motor 101 in the c and d directions as shown in the drawing by the cam mechanism, and the movable document table 3 is raised and pushed by the upper surface of the document on the movable table 3 to be raised in the c direction. The upper limit can be detected by the sensor 8. The paper feed belt 9 is driven in the paper feed direction by the normal rotation of the paper feed motor 102, and the reverse roller 10 is driven to rotate in the reverse direction to the paper feed by the normal rotation of the paper feed motor 102. The document is separated, and only the uppermost document can be fed.

  The registration unit C includes a pull-out roller 12 that conveys the document conveyed from the separation feeding unit B toward the turn unit D, an abutment sensor 11 that detects the document conveyed toward the pull-out roller 12, and a pull-out roller. The document width sensor 13 detects the length of the document conveyed from the roller 12 in the width direction. A plurality of document width sensors 13 are arranged in the depth direction and detect the size in the width direction orthogonal to the transport direction of the document transported by the pull-out roller 12. Further, the length of the document in the conveyance direction is detected from the motor pulse by reading the leading and trailing edges of the document with the abutment sensor 11.

  The turn portion D includes an intermediate roller 14, a reading entrance sensor 15 provided on the downstream side of the intermediate roller 14, and a first reading entrance that conveys the document conveyed from the registration portion C toward the reading position 20 of the reading glass 21. A roller 16 and a registration sensor 17 that detects a document conveyed by the first reading entrance roller 16 are provided.

  The first reading conveyance unit E includes a first reading unit 19 provided with a reading glass 21 that reads a surface image of a document, a belt unit 75 that conveys the document while contacting the reading glass 21, and a first reading entrance roller 16. A reading inlet guide 18 that guides the document conveyed from the reading glass 21 and the white background plate, and a first reading exit roller 23 that conveys the document that has passed through the reading position 20 toward the second reading conveyance unit F. And a paper discharge sensor 24 that detects a document that has passed through the first reading exit roller 23.

  As shown in FIG. 2, the belt unit 75 includes a driving roller 77, a driven roller 79, and an endless reading belt 81 wound around the driving roller 77 and the driven roller 79. Inside the reading belt 81, a pressing roller 80 that presses the inner periphery of the reading belt 81 toward the reading glass 21 is disposed.

  The drive roller 77 is one in which one and the other (a plurality of) roller portions 83a and 83b are supported by one drive shaft 85 provided over the entire width direction of the reading belt 81. A pulley 87 is fixed to one end of the drive shaft 85, and the driving force of the reading motor 103 is transmitted by a timing belt 89 wound around the pulley 87. The drive shaft 85 and the shaft of the driven roller 79 are supported by a support member.

  The one and other roller portions 83a and 83b have substantially the same width, and are provided over the entire width direction of the reading belt 81 in combination.

  As shown in FIG. 1, the one and other roller parts (at least one roller part) 83a, 83b are connected to the drive shaft 85 via one-way clutches 91a, 91b, and the one and other roller parts 83a, 83b. Is rotated integrally with the drive shaft 85 only in the drive direction of the reading belt 81 (in the direction of arrow P in FIG. 1). That is, the one and other roller portions 83 a and 83 b can rotate only in the driving direction of the reading belt 81 with respect to the driving shaft 85.

  As shown in FIG. 4, the second reading conveyance unit F includes a second reading unit 25 that reads a back side image of a document, a second reading roller 26 that conveys the document while suppressing the floating of the document, and a first reading exit roller. And a second reading exit roller 27 for transporting the document transported by 23 to the paper discharge unit G.

  The paper discharge unit G has a paper discharge roller 28 that discharges the originals whose front and back images have been read to the stack unit H.

  As shown in FIG. 3, the controller 100 is provided so as to be able to communicate with the main body control unit 111 of the image forming apparatus 71 that controls the automatic document feeder 70 via an I / F (interface) 107. On the input side of the controller 100, the registration sensor 17, the document set sensor 5, the paper discharge sensor 24, the abutment sensor 11, the reading entrance sensor 15, the document table lift sensor 8, the bottom plate home position sensor 6, the document length Sensors 30 and 31 are connected. Further, a pickup motor 101, a paper feed motor 102, a reading motor 103, a paper discharge motor 104, a bottom plate raising motor 105, and a second reading conveyance unit 25 are connected to the output side of the controller 100. The image data of the second reading and conveying unit 25 is transmitted to the main body control unit 111.

  The operation of the automatic document feeder 70 according to the present embodiment will be described. When a paper feed button is pressed in the operation unit 108 of the image forming apparatus main body 73 and a document paper feed signal is transmitted from the main body control unit 111 to the controller 100 via the I / F 107, the pickup roller 7 moves the paper feed motor 102. Are rotated by the forward rotation of the original, and several (ideally, one) originals on the original table 2 are picked up. The original separated by the action of the paper feeding belt 9 and the reverse roller 10 is further fed by the paper feeding belt 9, and the leading edge is detected by the abutting sensor 11 and further abuts against the pull-out roller 12 stopped. Then, a predetermined distance is fed from the detection of the abutting sensor 11, and as a result, the paper feeding motor 102 is stopped while being pressed against the pull-out roller 12 with a predetermined amount of bending, thereby supplying the paper. The driving of the paper belt 9 is stopped. At this time, the pickup motor 101 is rotated so that the pickup roller 7 is retracted from the upper surface of the original and the original is fed only by the conveying force of the paper feed belt 9, whereby the leading edge of the original enters the nip between the upper and lower roller pairs of the pull-out roller 12. Then, tip alignment (skew correction) is performed.

  When the document is transported from the resist section C to the turn section D by driving the pull-out roller 12 and the intermediate roller 14, the transport speed at the resist section C is set higher than the transport speed at the first reading transport section E. Thus, the processing time for sending the document to the first reading unit 19 is shortened.

  When the leading edge of the document is detected by the reading entrance sensor 15, before the leading edge of the document enters the nip between the pair of upper and lower rollers of the first reading entrance roller 16, deceleration is started in order to make the document transportation speed the same as the reading transportation speed. At the same time, the reading motor 103 is driven forward to drive the belt unit 75, the first reading inlet roller 16, the first reading outlet roller 23, and the second reading outlet roller 27. When the registration sensor 17 detects the leading edge of the document, it decelerates over a predetermined conveyance distance, temporarily stops before the reading position 20, and transmits a registration stop signal to the main body control unit 111 via the I / F 107. . Subsequently, when a reading start signal is received from the main body control unit 111, the document whose registration has been stopped is transported at an increased speed so as to rise to a predetermined transport speed before the leading end of the document reaches the reading position 20. At the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the first reading unit 19, a gate signal indicating an effective image area in the sub-scanning direction on the first surface is sent to the main body control unit 111 in the first reading. The data is transmitted until the trailing edge of the original is removed from the unit 19.

  When the reading motor 103 is driven, a driving force directed in the direction of the arrow P in FIG. 1 is transmitted to the driving shaft 85 of the belt unit 75, and at the same time, the one-way clutches 91a and 91b are connected to one and the other roller portions 83a, 83b rotates in the direction of arrow P integrally with the drive shaft 85. Then, the reading belt 81 circulates in the direction of the arrow P by the frictional force acting between the one and other roller portions 83a, 83b and the reading belt 81.

  In general, in a belt unit in which a wide endless belt is wound around a driving roller and a driven roller, the belt circumferential length is partially due to a partial difference in frictional force acting between the driving roller and the inner circumference of the belt. Therefore, the belt may be twisted, and the belt may be twisted. If the belt is driven while the belt is twisted, problems such as wrinkling of the belt, meandering of the belt, and extension of the belt occur. In the automatic document feeder, this problem causes skew in the conveyed document and disturbs the read image, or causes the document to jam in the conveyance path.

  Therefore, this embodiment will be considered. For example, when the frictional force acting between one roller portion 83a and the reading belt 81 is larger than the frictional force acting between the other roller portion 83b and the reading belt 81, The roller part 83a side precedes the other roller part 83b side, and tension to force the reading belt 81 to twist (force to rotate the other roller part 83b in the direction of arrow P in FIG. 1) is generated. To do.

  If the reading belt 81 is continuously driven in this state, the force for rotating the other roller portion 83b in the direction of arrow P increases, and the one-way clutch 91b is disengaged. As a result, the other roller portion 83b rotates in the direction of arrow P with respect to the drive shaft 85, and the other roller portion 83b side of the reading belt 81 catches up with the preceding one roller portion 83a side. Twisting is prevented. Thereafter, the one-way clutch 91b is connected again, and the driving force is transmitted to the other roller portion 83b.

  Further, when the frictional force acting between the other roller part 83b and the reading belt 81 is larger than the frictional force acting between the one roller part 83a and the reading belt 81, the other of the reading belt 81 The roller part 83b side precedes the one roller part 83a side. In this case as well, the same result as described above can be obtained.

  In the case of reading the document only on the front side, the document that has passed through the first reading unit 19 is conveyed to the paper discharge unit G through the second reading unit 25. At this time, when the leading edge of the original is detected by the paper discharge sensor 24, the paper discharge motor 104 is driven to rotate forward to rotate the paper discharge roller 28 counterclockwise. In addition, the discharge motor pulse count from the detection of the leading edge of the document by the discharge sensor 24 reduces the discharge motor drive speed immediately before the trailing edge of the document comes out of the nip of the pair of upper and lower rollers of the discharge roller 28 to discharge the document. Control is performed so that the document discharged onto the tray 29 does not jump out.

  In the case of double-sided document reading, the controller for the second reading unit 25 is detected at the timing when the document leading edge reaches the second reading unit 25 by the pulse count of the reading motor 103 after the paper discharge sensor 24 detects the document leading end. A gate signal indicating an effective image area in the sub-scanning direction is transmitted from the section 100 through the first reading section 19 until the trailing edge of the document is removed. The second reading roller 26 serves as a reference white part for obtaining shading data in the second reading unit 25 as well as suppressing floating of the original in the second reading unit 25.

  Next, an outline of the operation of the image forming apparatus 1 according to the present embodiment will be described. In response to a paper feed signal from the operation unit 108 of the image forming apparatus main body, paper (recording medium) is supplied from the paper feed tray to the image forming unit, and an image of the original read by the automatic document feeder 70 is supplied to the paper. It is formed. The paper on which the image has been formed is discharged to a paper discharge unit.

  Next, operations and effects of the automatic document feeder 70 according to the present embodiment will be described. According to the present embodiment, the one and other roller portions 83a and 83b arranged on one drive shaft 85 are simply configured to rotate integrally with the drive shaft 85 only in the drive direction of the reading belt 81. Even if a biased tension occurs in the reading belt 81 due to variations in the frictional force acting between the reading belt 81 and each of the roller portions 83a and 83b, one roller portion 83a or the other roller portion 83b is driven by the drive shaft 85. In contrast, since the belt rotates in the belt drive direction (arrow P direction), the reading belt 81 can be prevented from twisting.

  Since the one and other roller portions 83a and 83b are connected to the drive shaft 85 via the one-way clutches 91a and 91b, either the one roller portion 83a side or the other roller portion 83b side of the reading belt 81 is preceded. Even in this case, the reading belt 81 can be prevented from being twisted.

  Since the driving force is constantly transmitted to one or both of the first and second roller portions 83a and 83b, the reading belt 81 can be driven reliably.

  The one and other roller portions 83a and 83b can rotate in the drive direction of the reading belt 81 (direction of arrow P) with respect to the drive shaft 85 by the action of the one-way clutches 91a and 91b. Even if the document becomes jammed, the jam processing is easy.

  It is possible to provide an automatic document feeder (image reading apparatus) 70 including a belt unit 75 that exhibits the same effects as the present embodiment.

  It is possible to provide the image forming apparatus 1 provided with the automatic document feeder (image reading apparatus) 70 having the same effects as the present embodiment.

  Next, another embodiment of the present invention will be described. In the following description, parts having the same operational effects as those of the first embodiment described above are denoted by the same reference numerals, and the parts thereof are described. Detailed description will be omitted, and the following description will mainly focus on differences from the first embodiment described above.

  A second embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the drive roller of the belt unit according to the present embodiment.

  In the present embodiment, as shown in FIG. 5, one roller portion 83a is fixed to drive shaft 85 (is integrally formed with drive shaft 85), and the other roller portion 83b and drive shaft 85 are The other roller portion 83b is coupled to the drive shaft 85 only in the drive direction of the reading belt 81 (in the direction indicated by the arrow P in FIG. 5). That is, the other roller portion 83 b can rotate only in the driving direction of the reading belt 81 with respect to the driving shaft 85.

  When the reading motor 103 is driven, one roller portion 83a starts to rotate in the direction of arrow P together with the drive shaft 85. At the same time, the one-way clutch 91b is connected, and the other roller portion 83b moves in the direction of arrow P together with the drive shaft 85. Rotate to. The reading belt 81 circulates and moves due to the frictional force acting between the reading belt 81 and the one and other roller portions 83a and 83b.

  If the belt continues to circulate in a state where one roller portion 83a side of the reading belt 81 precedes the other roller portion 83b side, the one-way clutch 91b is eventually disconnected. As a result, the other roller portion 83b rotates in the direction of arrow P with respect to the drive shaft 85, and the other roller portion 83b side of the reading belt 81 catches up with the preceding one roller portion 83a side. Twisting is prevented. Thereafter, the one-way clutch 91b is connected again, and the driving force is transmitted to the other roller portion 83b.

  According to the present embodiment, since one roller portion 83a is fixed to the drive shaft 85, the one roller portion 83а is also used while the one-way clutch 91b is disconnected and the driving force is not transmitted to the other roller portion 83b. A driving force can be transmitted to the reading belt 81.

  By integrally molding the one roller portion 83a and the drive shaft 85, the number of parts can be reduced.

  When one roller portion 83a side of the reading belt 81 precedes the other roller portion 83b side, the reading belt 81 can be prevented from being twisted.

  It is possible to provide an automatic document feeder (image reading apparatus) 70 including a belt unit 75 that exhibits the same effects as the present embodiment.

  It is possible to provide the image forming apparatus 1 provided with the automatic document feeder (image reading apparatus) 70 having the same effects as the present embodiment.

  A third embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the drive roller of the belt unit according to this embodiment.

  In the present embodiment, the one roller portion 83а and the drive shaft 85 are connected via a one-way clutch 91а, and the one roller portion 83а is only in the driving direction of the reading belt 81 (the direction of arrow P in FIG. 6). It rotates together with the drive shaft 85. That is, the one roller portion 83a is rotatable only in the driving direction of the reading belt 81 with respect to the driving shaft 85.

  The other roller portion 83 b is supported so as to be freely rotatable with respect to the drive shaft 85.

  When the reading motor 103 is driven, the drive shaft 85 starts to rotate in the direction of arrow P in FIG. 6, and at the same time, the one-way clutch 91a is connected, and one roller portion 83a rotates in the direction of arrow P. The reading belt 81 circulates and moves in the direction of arrow P due to the frictional force acting between the reading belt 81 and one of the rollers 83a. The other roller portion 83b is rotated around the reading belt 81 by the frictional force acting between the reading belt 81 and the other roller portion 83b.

  Here, when one roller portion 83a side of the reading belt 81 precedes the other roller portion 83b side, the other roller portion 83b rotates in the direction of arrow P with respect to the drive shaft 85, and the other side of the reading belt 81 The roller portion 83b side catches up with the preceding roller portion 83a side, so that the reading belt 81 is prevented from being twisted.

  Further, when the reading belt 81 continues to circulate in a state where the other roller portion 83b side of the reading belt 81 precedes the one roller portion 83a side, the one-way clutch 91a is eventually disconnected. As a result, the one roller portion 83a rotates in the direction of arrow P with respect to the drive shaft 85, and the one roller portion 83а side of the reading belt 81 catches up with the preceding other roller portion 83b side. Twisting is prevented. Thereafter, the one-way clutch 91a is connected again, and the driving force is transmitted to the one roller portion 83a.

  According to the present embodiment, one roller portion 83a is connected to the drive shaft 85 via the one-way clutch 91a, and the other roller portion 83b is freely rotatable with respect to the drive shaft 85. Using the clutch 91a, the reading belt 81 can be prevented from being twisted regardless of which one of the roller part 83a side and the other roller part 83b side of the reading belt 81 precedes.

  One roller portion 83a can be rotated in the driving direction of the reading belt 81 (direction of arrow P) with respect to the drive shaft 85 by the action of the one-way clutch 91a, and the other roller portion 83b is driven with respect to the drive shaft 85. Therefore, even if the document jams while the document is being conveyed by the belt unit 75, the jam processing is easy.

  It is possible to provide an automatic document feeder (image reading apparatus) 70 including a belt unit 75 that exhibits the same effects as the present embodiment.

  It is possible to provide the image forming apparatus 1 provided with the automatic document feeder (image reading apparatus) 70 having the same effects as the present embodiment.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

  In the embodiment described above, one or both of the one and other roller portions 83a and 83b are connected to the drive shaft 85 via the one-way clutch, but instead, the one and other roller portions 83a. , 83b may be connected to the drive shaft 85 via a one-way bearing or a ratchet.

  In the above-described embodiment, two roller portions are arranged on the drive shaft 85. However, the present invention is not limited to this. For example, three roller portions are arranged on the drive shaft 85, and the two roller portions on both outer sides are arranged in one way. It may be connected to the drive shaft 85 via a clutch, and the central roller portion may be fixed to the drive shaft 85 or provided so as to be rotatable in any direction with respect to the drive shaft 85.

  In the above-described embodiment, the one and other roller portions 83a and 83b are provided over the entire width direction of the reading belt 81. However, the present invention is not limited to this, and the width of each roller portion 83a and 83b is reduced. Thus, the contact area with the reading belt 81 may be reduced.

  In the above-described embodiment, the image forming apparatus 71 is a copying machine including an image reading unit. However, the image forming apparatus 71 is not limited thereto, and may be a printer or the like that does not include an image reading unit.

  In the above-described embodiment, the belt unit 75 is provided in the first reading conveyance unit E, but instead, the belt unit 75 is provided in the image forming unit of the image forming apparatus main body 73 and the belt unit 75 uses the paper. An image may be formed on a sheet while conveying the (recording medium). An image forming apparatus provided with an image forming unit having a belt unit 75 that exhibits the same effects as those of the above-described embodiment can be provided.

It is a cross-sectional view which extracts and shows the drive roller of the belt unit which concerns on 1st Embodiment. (A) is a top view of the belt unit which concerns on 1st Embodiment, (b) is a side view of the belt unit which concerns on 1st Embodiment. FIG. 3 is a block diagram illustrating a control configuration of the image forming apparatus according to the first embodiment. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment. It is a cross-sectional view which extracts and shows the drive roller of the belt unit which concerns on 2nd Embodiment. It is a cross-sectional view which extracts and shows the drive roller of the belt unit which concerns on 2nd Embodiment.

Explanation of symbols

70 Automatic document feeder (image reading device)
71 Image forming device 75 Belt unit 77 Drive roller 79 Followed roller 81 Reading belt (endless belt)
83a, 83b One and the other roller part 85 Drive shaft

Claims (5)

  A driving roller, a driven roller, and an endless belt wound around the driving roller and the driven roller, the driving roller being coaxial with the driving shaft and a driving shaft provided over the entire belt in the width direction And a plurality of roller portions arranged in the belt unit, wherein at least one roller portion rotates integrally with the drive shaft only in the drive direction of the belt.   The belt unit according to claim 1, wherein at least one roller portion is fixed to a drive shaft.   An image reading apparatus comprising the belt unit according to claim 1, and reading an image while conveying a document by the belt unit.   An image forming apparatus comprising the image reading apparatus according to claim 3, wherein an image read by the image reading apparatus is formed on a recording medium.   An image forming apparatus comprising the belt unit according to claim 1, wherein an image is formed while a recording medium is conveyed by the belt unit.

Images