JP2009097634A - Image reading device and image forming device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading device capable of accurately moving a carriage stably, and to provide an image forming device equipped with the same. <P>SOLUTION: The image reading device 5 is equipped with a first and a second carriage 71, 72 supported movably in a scanning direction; a pair of driving wires 26a connected to these carriages 71, 72; a pair of driving pulleys 25 around which each of the wires 26a is wound, and a driving shaft 231 which fixes this pair of the driving pulleys 25 at both sides. Each of the wires 26a is driven by the rotation of the pair of the driving pulleys 25 to move the first and second carriage 71, 72, and a manuscript imege is read by making reflected light from a manuscript face incident on an image sensor while scanning the manuscript surface. The pair of driving pulleys 25 is fixed toward the same direction on the driving shaft 231, and the pair of the driving wires is wound around the respective driving pulleys 25 in the same direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that drives a carriage by a wire wound around a driving pulley and driven, and an image forming apparatus including the image reading apparatus.

  Copiers, facsimiles, printers, and the like are provided with an image reading device that reads an image of an original by exposing and scanning the original with a moving optical system. In this case, for example, the optical system is movably provided with a first carriage on which a lamp as a light source and a first mirror are mounted, and a second carriage on which second and third mirrors are mounted. The carriage and the second carriage are moved in the same direction with a predetermined relationship, and the original image is formed on the image sensor while keeping the optical path length constant. The first and second carriages are moved by connecting the first and second carriages to drive wires wound around the drive pulley, respectively, and controlling the rotation of the drive pulley.

  Thus, in the image reading apparatus that drives the optical system with the drive wire, the carriage is driven at a constant speed in the original reading range in order to keep the original magnification constant. Therefore, it is necessary to minimize the difference in the diameter of the peripheral surface around which the drive wire of the drive pulley is wound in the axial direction. However, depending on the configuration and processing method of the drive pulley, the peripheral surface portion may be rounded or recessed, or the peripheral surface portion may be conical, and the diameter of the peripheral surface portion may vary slightly. is there. If the diameter of the peripheral surface portion differs in the axial direction, for example, at the start of scanning drive, the drive wire fed out from the drive pulley becomes long, while on the other hand, the drive pulley is almost immediately after the end of scanning drive. The drive wire that is fed out from the arm is shortened. When the length of the drive wire wound around the drive pulley is different between the central portion and the end portion of the peripheral surface in the axial direction, the drive speed for scanning the carriage changes, and a magnification error for reading a document image occurs. is there. In addition, when the length of the drawn-out drive wire changes, the wire tension changes, causing load fluctuations and speed fluctuations. If the wire tension is not applied at all, the wires fall off and drive backlash occurs. It will be.

  Therefore, in Patent Document 1, flanges are provided on both sides of the circumferential surface portion around which the drive wire is wound, and the drive wires are wound from the notches provided in the flange toward the center portion from both axial ends of the circumferential surface portion. Accordingly, since the length of the drive wire wound around the drive pulley is constant, the length of the drive wire being fed out is not changed. In addition, at least one turn (360 degrees) or more of the drive wire is wound around the end of the peripheral surface portion with roundness or dent so that the diameter of the peripheral surface portion can be increased. Since different parts can be disabled, the length of the wire being fed is not changed.

However, in the above-described prior art, the two drive pulleys are fixed to both sides of the drive shaft by screws or the like, and are arranged symmetrically with respect to the scanning direction. Since each drive pulley is arranged symmetrically, for example, if each end on the outer side of the device is recessed and each end on the inner side of the device is rounded on the peripheral surface of each drive pulley, Both diameters are small and the inside diameter of the device is large. In such a device in which each drive pulley is assembled, the drive shaft rotates so that one drive pulley sequentially feeds the drive wire wound inside the device from the drive wire wound around the outer end of the device, and at the same time the other When the driving wire wound around the outer end of the device is sequentially fed out from the driving wire wound around the outer peripheral portion of the peripheral surface portion, the driving wire fed out from one driving roller is short and fed out from the other driving roller. The drive wire to be lengthened becomes long. When the lengths of the drive wires fed out from the two drive pulleys are different in this way, the scanning drive speed is different on both sides of the carriage, and there is a problem that the read original image is distorted into a trapezoidal shape, a parallelogram shape, or the like. . Further, since the length of the drive wire fed out by the two drive pulleys changes, the two wire tensions differ, the load fluctuates, and the carriage may not move smoothly.
JP 2003-167301 A (paragraphs [0025], [0026], FIGS. 5 and 6)

  SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus capable of stably and accurately moving a carriage and an image forming apparatus including the image reading apparatus. And

  To achieve the above object, the present invention provides a carriage supported so as to be movable in a scanning direction, a pair of drive wires connected to the carriage, a pair of drive pulleys around which the drive wires are wound, A drive shaft for fixing a pair of drive pulleys on both sides, driving each of the drive wires by the rotation of the pair of drive pulleys, moving the carriage, and reflecting from the document surface while scanning the document surface In the image reading apparatus that reads an original image by causing light to enter the image sensor, the pair of drive pulleys are fixed in the same direction on the drive shaft, and the pair of drive wires are connected to the drive pulleys. It is characterized by being wound in the same direction.

  According to this configuration, even if the diameter of the portion where the drive wire of each drive pulley is wound is different in the drive shaft direction, each drive pulley is fixed in the same direction on the drive shaft, and each drive wire is Since each drive wire is drawn out from each drive pulley in the same direction from the same position in the drive axis direction by being wound around the drive pulley in the same direction, the length of the drive wire drawn out from each drive pulley is Be the same.

  In the invention of claim 2, the pair of drive wires are formed in the same twist direction. According to this configuration, the same elasticity and elongation can be given to each drive wire fed out from each drive pulley.

  According to a third aspect of the present invention, there is provided an image forming apparatus equipped with the image reading apparatus having the above configuration.

  According to the first aspect of the present invention, each drive pulley is fixed in the same direction on the drive shaft even if the diameter of the portion around which the drive wire of each drive pulley is wound is different in the drive shaft direction. Since each drive wire is wound around each drive pulley in the same direction, each drive wire is fed out from each drive pulley in the same direction from the same position in the drive shaft direction, so the drive fed out from each drive pulley The wire length is the same. Therefore, since the carriage can be accurately moved, there is no possibility that the original image to be read is distorted into a trapezoidal shape, a parallelogram shape, or the like, and the tension of each driving wire is substantially the same, which stabilizes the carriage. Can be moved.

  According to the second aspect of the present invention, since each drive wire fed out from each drive pulley can have the same elasticity and elongation, the tension of each drive wire becomes substantially the same, and the carriage is stabilized. Can be moved.

  According to a third aspect of the present invention, when the image reading apparatus is provided, an image forming apparatus is provided that obtains a read original image without distortion by moving the carriage stably and accurately. can do.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The embodiment of the present invention shows the most preferable form of the invention, and the use of the invention and the terms shown here are not limited thereto.

  FIG. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 includes a paper feeding unit 1 disposed at a lower portion of the apparatus main body, a paper transporting unit 2 disposed on the right side and above the paper feeding unit 1, and an upper side of the paper transporting unit 2. The disposed image forming unit 3, the fixing unit 4 disposed downstream of the image forming unit 3 in the sheet conveying direction, and the image disposed above the image forming unit 3 and the fixing unit 4. A reading unit 5 and a document feeding unit 6 disposed above the image reading unit 5 are provided. The image reading unit 5 is an example of the image reading apparatus of the present invention.

  The paper feeding unit 1 is configured to feed a stack of papers stacked on a paper feeding cassette 11 detachably attached to the apparatus main body by a rotation operation of a paper feeding roller 12 having an arc outer peripheral part. Are fed to the paper transport unit 2 one by one from the topmost sheet by feeding the paper by the paper feeding unit 13 provided at the upper right end of each paper feed cassette 11. It is supposed to be.

  The sheet conveying unit 2 conveys the sheet fed from the sheet feeding unit 1 toward the image forming unit 3 by the conveying roller pair 21 and the registration roller pair 22, and further, the image forming unit 3 transfers the image at the fixing unit 4. The formed paper is discharged onto the discharge tray 24 by the discharge roller pair 23.

  The image forming unit 3 forms a predetermined toner image on a sheet by an electrophotographic process, and a photoconductive drum 31 having a photoconductivity supported rotatably and around the photoconductive drum 31. A charging unit 32, an exposure unit 33, a developing unit 34, a transfer unit 35, a cleaner 36, and a charge eliminating unit 37 are provided.

  The charging unit 32 includes a charging wire to which a high voltage is applied, and applies a predetermined potential to the surface of the photosensitive drum 31 by corona discharge from the charging wire. The exposure unit 33 irradiates the photosensitive drum 31 with laser light output from a laser emitter based on image data of a document read by the image reading unit 5 described later via a polygon mirror and a reflecting mirror. The surface of the photosensitive drum 31 is selectively attenuated to form an electrostatic latent image on the surface of the photosensitive drum 31. The developing unit 34 develops the electrostatic latent image with toner and forms a toner image on the surface of the photosensitive drum 31. The transfer unit 35 transfers the toner image on the surface of the photosensitive drum 31 onto a sheet. The cleaner 36 removes toner remaining on the surface of the photosensitive drum 31 after transfer. The static elimination unit 37 removes residual charges on the surface of the photosensitive drum 31.

  The fixing unit 4 fixes the toner image on the sheet by heating the sheet on which the toner image has been transferred in the image forming unit 3 between the heating roller 41 and the pressure roller 42.

  The document feeder 6 automatically conveys the documents placed on the document tray 61 one by one in response to an input instruction to start copying (copying), and the document discharge tray after exposure scanning of the document. (Not shown) A so-called sheet-through type document reading is performed to be discharged upward.

  The image reading unit 5 irradiates light on a document transferred by the document feeding unit 6 or a document placed on a contact glass, and reads the image information of the document by converting the reflected light into an electric signal. At the same time, image data corresponding to the document image is generated.

  FIG. 2 is a schematic cross-sectional view illustrating an image reading unit of the image forming apparatus. The image reading unit 5 includes a contact glass 8 on which the document P is placed, a scanner unit 7 that reads image information of the document P, and generates image data from the read image of the document P.

  The scanner unit 7 is disposed at a proper position below the first carriage 71 disposed above the scanner unit 7, the second carriage 72 disposed on the left side of the first carriage 71, and the scanner unit 7. The imaging unit 80 and the like.

  The first carriage 71 and the second carriage 72 are connected to a scanning mechanism section, which will be described later, and the scanning mechanism section moves on the contact glass 8 by moving in the arrow direction (left-right direction) shown in FIG. It is possible to scan the entire surface of the document P placed on the image and read image information on the entire surface of the document.

  The first carriage 71 includes a frame 75 connected to the scanning mechanism unit, a light source 76 such as an exposure lamp that irradiates light on the document P placed on the contact glass 8, and light from the contact glass 8. 2 includes a mirror 78 that reflects toward the carriage 72.

  The second carriage 72 is provided with a pair of mirrors 72a and 72b disposed so as to face each other in the vertical direction. Light from the mirror 78 of the first carriage 71 is sequentially reflected by the mirrors 72a and 72b, and the imaging unit 80. Lead to.

  The imaging unit 80 includes an imaging lens 73 and an image sensor 74 disposed on the right side of the imaging lens 73.

  The imaging lens 73 has a plurality of lenses for imaging the reflected light from the original P incident through the mirror 72 b of the second carriage 72, and is fixed at a predetermined position of the imaging unit 80. The

  The image sensor 74 has an image sensor such as a CCD arranged in the longitudinal direction (the depth direction in FIG. 2) on the optical axis Z of the imaging lens 73, and is imaged on the image sensor by the imaging lens 73. The optical image of the original P is converted into an electric signal.

  In the image reading unit 5 configured as described above, light is irradiated onto the contact glass 8 by the light source 76, and reflected light from the document P on the contact glass 8 is reflected by the mirror 78 of the first carriage 71, and the reflection thereof. The light is sequentially reflected by the mirrors 72 a and 72 b of the second carriage 72, and an optical image of the document P is formed on the image sensor 74 via the imaging lens 73. Thereby, a part of the document P is read. Then, the scanning mechanism unit moves the first carriage 71 and the second carriage 72 at a predetermined speed, thereby scanning the entire surface of the document P, reading the entire surface of the document P, and forming a read image.

  FIG. 3 is a perspective view showing a scanning mechanism for driving the first and second carriages shown in FIG. In this example, the pulleys driven by the driving pulley 25 and the driving wire 26 are attached to the first driven pulley 271 and the second driven pulley 273 fixed to the image reading unit main body and the second carriage 72. A moving pulley 272 is employed. A driving wire 26 is wound and stretched between the pulleys 271 to 273 and the driving pulley 25. The drive pulley 25 is fixedly held on both sides of the drive shaft 231, and the pulleys 271 to 273 and the drive wire 26 are also arranged on both sides of the first and second carriages 71 and 72.

  Each drive wire 26 includes a first drive wire 26a and a second drive wire 26b. Each first drive wire 26a starts from the drive pulley 25 and is first bridged from the lower side of the first driven pulley 271 and then reversed by 180 degrees, and then is bridged from the upper side to the inner groove of the moving pulley 272. Has been. A round terminal 281 is fixed to the tip of the first drive wire 26a. The first drive wire 26a is further inverted 180 degrees at the position of the moving pulley 272, and the round terminal 281 is provided on the main body frame. It is hooked on the hook portion 221. Similarly, starting from the drive pulley 25, each second drive wire 26b is first bridged from the lower side with respect to the second driven pulley 273 and then reversed by 180 degrees, and then lowered to the outer groove of the moving pulley 272. It is bridged from the side. A round terminal 282 is also fixed to the tip of each second drive wire 26b. The second drive wire 26b is further inverted 180 degrees at the position of the moving pulley 272 and further bent inward 90 degrees by the wire guide 274. In this state, the round terminal 282 is hooked on a tension spring 275 fixed to the main body.

  In such a wire scanning mechanism, the first carriage 71, which is abbreviated by a dotted line in the figure, is interposed between the first driven pulley 271 and the moving pulley 272, and the first drive wire 26a is stretched around the first driven wire 26a. It is fixed to. Similarly, a moving pulley 272 is attached to the second carriage 72, which is abbreviated as a dotted line in the drawing, and the moving pulley 272 moves in the arrow direction S in FIG. It is possible. Here, when the drive pulley 25 rotates, a moving force is generated in the stretching direction of the drive wire 26, that is, in the feeding-out direction or the winding-up direction of the drive wire 26, and the moving force is fixed to the first drive wire 26a. One carriage 71 moves in the arrow direction S in FIG. Further, rotational movement force acts on the moving pulley 272, and the second carriage 72 also moves in the arrow direction S in FIG. Normally, the moving speed of the first carriage 71 is set to be twice that of the second carriage 72. Due to this speed difference, the entire original P is scanned while keeping the optical path length of the imaging lens 73 (see FIG. 2) constant. To do.

  FIG. 4 is a plan view showing the configuration of the drive pulley fixed to the drive shaft. The drive shaft 231 is disposed so as to be orthogonal to the moving direction S of the first and second carriages 71 and 72. The drive shaft 231 is provided with two drive pulleys 25 on the left and right sides of FIG. 4 at an interval, and a motor pulley 82 is provided at one end thereof. The drive belt 83 is stretched between the motor pulley 81 provided on the motor shaft 29a of the motor 29 so that the motor pulley 82 is rotationally driven by a motor 29 constituted by a step motor capable of forward and reverse rotation as a drive source. It is built.

  Each drive pulley 25 has a peripheral surface portion 25a, flange portions 25b and 25c, and a bearing portion 25d.

  The peripheral surface portion 25a is where the first and second drive wires 26a and 26b (see FIG. 3) are wound, and flange portions 25b and 25c are provided on both sides thereof. The first and second drive wires 26a and 26b are wound around the peripheral surface portion 25a between the flange portions 25b and 25c.

  The bearing portion 25d is formed in a sleeve shape at the center of the drive pulley 25, and allows the drive shaft 231 to pass therethrough. A hole for fitting a screw or the like for fixing the inserted drive shaft 231 at a predetermined position is formed in the bearing portion 25d.

  Since each drive pulley 25 is made of plastic and has the same shape, it is molded by the same mold. When the driving pulley 25 is molded, the corners of the peripheral surface portion 25a and the flange portions 25b and 25c are not right angles and are easily rounded. Moreover, the magnitude | size of the roundness may differ in the flange parts 25b and 25c. Further, the diameter of the peripheral surface portion 25a may be different in the axial direction of the drive shaft 231. Even if the metal pulley is subjected to sheet metal processing such as drawing to form the drive pulley 25, the diameter of the peripheral surface portion 25a may differ in the axial direction of the drive shaft 231 as described above. When the drive pulleys 25 thus processed are attached to the drive shaft 231 symmetrically with respect to the moving direction S, the lengths of the wires fed out from the drive pulleys 25 are different. If the lengths of the drive wires fed out from the two drive pulleys are different, there is a problem that the scanning drive speed is different on both sides of the carriage, and the read original image is distorted into a trapezoidal shape, a parallelogram shape, or the like.

  Therefore, in this embodiment, each drive pulley 25 is fixed in the same direction on the drive shaft 231, and the drive shaft direction positions fed out from the peripheral surface portion 25a of the drive wire wound around each drive pulley 25 are the same. It is trying to become. That is, by fixing each bearing portion 25d to the drive shaft 231 with a screw so that each flange portion 25c is on the motor pulley 82 side with respect to each circumferential surface portion 25a, the roundness and diameter of each circumferential surface portion 25a are increased. Even if there is a difference, the diameter of each peripheral surface portion 25a is the same at the same position in the axial direction from each flange portion 25c. When the drive wires are drawn out at the same position in the same axial direction, the lengths of the drive wires drawn out from the two drive pulleys 25 become the same.

  The configuration of winding the driving wire around each driving pulley 25 and the feeding operation thereof will be described in detail. FIG. 5 is a plan view showing a state where the drive wire is wound around the drive pulley.

  A first drive wire 26a and a second drive wire 26b are wound around each drive pulley 25, and each first drive wire 26a is stretched over a first driven pulley 271 (see FIG. 3). The wire 26b is stretched over the second driven pulley 273 (see FIG. 3).

  In the drive pulley 25 on the right side of FIG. 5, the first drive wire 26a is fixed to a notch 41 provided in the flange portion 25c, and is wound with S winding from the flange portion 25c toward the center in the axial direction of the peripheral surface portion 25a. On the other hand, the second drive wire 26b is fixed to a notch 42 provided in the flange portion 25b, and is wound with S winding from the flange portion 25b toward the center in the axial direction of the peripheral surface portion 25a. The first drive wire 26a and the second drive wire 26b are adjacent to each other at positions where they are fed to the first and second driven pulleys 271 and 273, and when the drive shaft 231 rotates, the first and second drive wires 26a and 26b are adjacent to each other. In this state, one drive wire is wound around the peripheral surface portion 25a, and the other drive wire moves in the drive axis direction while being drawn out from the peripheral surface portion 25a.

  In the drive pulley 25 on the left side of FIG. 5 as well, the first drive wire 26a is fixed to the notch 41 provided in the flange portion 25c and is directed from the flange portion 25c toward the center in the axial direction of the peripheral surface portion 25a. On the other hand, the second drive wire 26b is fixed to the notch 42 provided in the flange portion 25b, and wound in the S winding from the flange portion 25b toward the axial center of the peripheral surface portion 25a. Is done. The first drive wire 26a and the second drive wire 26b are adjacent to each other at positions where they are fed to the first and second driven pulleys 271 and 273, and when the drive shaft 231 rotates, the first and second drive wires 26a and 26b are adjacent to each other. In this state, one drive wire is wound around the peripheral surface portion 25a, and the other drive wire moves in the drive axis direction while being drawn out from the peripheral surface portion 25a.

  When the drive shaft 231 rotates and each first drive wire 26a is fed out from each drive pulley 25, each second drive wire 26b is wound around each drive pulley 25, and the first and second drive wires 26a, Both adjacent positions of 26b move to the flange portion 25c side. When the drive shaft 231 rotates in the reverse direction and each second drive wire 26b is fed out from each drive pulley 25, each second drive wire 26a is wound around each drive pulley 25, and the first and second drive wires 26a. , 26b move to the flange portion 25b side.

  Each first drive wire 26a is made of the same material and the same thickness, and the twist direction is Z-twist. Each second drive wire 26b is made of the same material and the same thickness, and the twist direction is Z-twist. The winding direction of the first drive wire 26a and the second drive wire 26b is not limited to S winding, and may be Z winding if both are the same winding direction. In this case, it is preferable to use an S twisted wire.

  According to the embodiment, the image reading device 5 includes the first and second carriages 71 and 72 supported so as to be movable in the scanning direction, the pair of drive wires 26a connecting the carriages 71 and 72, and A pair of drive pulleys 25 around which a drive wire 26 a is wound and a drive shaft 231 that fixes the pair of drive pulleys 25 on both sides are provided. The drive wires 26 a are driven by the rotation of the pair of drive pulleys 25, The original image is read by moving the first and second carriages 71 and 72 so that the reflected light from the original surface enters the image sensor 74 while scanning the original surface. The pair of drive pulleys 25 are fixed in the same direction on the drive shaft 231, and the pair of drive wires 26 a are wound around the drive pulleys 25 in the same direction.

  According to this configuration, even if the diameter of the peripheral surface portion around which the drive wire 26a of each drive pulley 25 is wound differs in the drive shaft direction, each drive pulley 25 is fixed in the same direction on the drive shaft 231. Since each drive wire 26a is wound around each drive pulley 25 in the same direction, each drive wire 26a is fed out from the same position in the axial direction of each drive pulley 25 in the same direction. The lengths of the drive wires 26a drawn out from 25 are the same. Accordingly, since the first and second carriages 71 and 72 can be accurately moved, there is no possibility that the read document image is distorted into a trapezoidal shape, a parallelogram shape, or the like, and the tension of each driving wire 26a is increased. The first and second carriages 71 and 72 can be moved smoothly and stably.

    Further, according to the above-described embodiment, the image reading apparatus 5 includes the second carriage 72 supported so as to be movable in the scanning direction, the pair of drive wires 26b connected to the carriage 72, and the drive wires 26b being wound. A pair of drive pulleys 25 and a drive shaft 231 that fixes the pair of drive pulleys 25 on both sides. The drive wires 26b are driven by the rotation of the pair of drive pulleys 25, and the second carriage 72 is moved. The original image is read by causing the image sensor 74 to receive the reflected light from the original surface while scanning the original surface. The pair of drive pulleys 25 are fixed in the same direction on the drive shaft 231, and the pair of drive wires 26 b are wound around the drive pulleys 25 in the same direction.

  According to this configuration, even if the diameter of the peripheral surface portion around which the drive wire 26 b of each drive pulley 25 is wound differs in the drive shaft direction, each drive pulley 25 is fixed in the same direction on the drive shaft 231. Since each drive wire 26b is wound around each drive pulley 25 in the same direction, each drive wire 26b is fed out from the same position in the axial direction of each drive pulley 25 in the same direction. The length of the drive wire 26b drawn out from 25 is the same. Therefore, since the second carriage 72 can be accurately moved, there is no possibility that the read original image is distorted into a trapezoidal shape or a parallelogram shape, and the tension of each drive wire 26b is substantially the same. The two carriages 72 can be moved smoothly and stably.

  Moreover, according to the said embodiment, a pair of drive wire 26a or 26b is formed in the same twist direction, and can give the same elasticity and elongation to each drive wire 26a or 26b drawn out from each drive pulley 25. Therefore, the tension of each drive wire 26a or 26b becomes substantially the same, and the first and second carriages 71 and 72 can be moved smoothly and stably.

  Further, according to the above-described embodiment, if the image forming apparatus 100 includes the image reading device 5, the first and second carriages 71 and 72 can be moved stably and accurately, and reading without distortion can be performed. An image forming apparatus 100 that obtains a document image can be provided.

  The present invention can be used in an image reading apparatus that drives a carriage by a wire that is wound around a driving pulley and driven, and an image forming apparatus that includes the image reading apparatus.

1 is a cross-sectional view showing an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an image reading unit of an image forming apparatus according to an embodiment of the present invention. These are the perspective views which show the scanning mechanism part of the image reading part which is embodiment of this invention. These are top views which show the structure of the drive pulley fixed to the drive shaft of the image reading part which is embodiment of this invention. These are top views which show the state which wound the wire around the drive pulley of the image reading part which is embodiment of this invention.

Explanation of symbols

5 Image reading unit (image reading device)
25 drive pulley 25a peripheral surface portion 25b, 25c flange portion 25d bearing portion 26 drive wire 26a first drive wire 26b second drive wire 29 drive motor 71 first carriage 72 second carriage 73 imaging lens 74 image sensor 80 imaging unit 81, 82 Motor pulley 83 Drive belt 100 Image forming apparatus 221 Hook 231 Drive shaft 271 First driven pulley 272 Moving pulley 273 Second driven pulley 274 Wire guide 275 Tension spring 281 282 Round terminal

Claims (3)

A carriage supported movably in the scanning direction, a pair of drive wires connected to the carriage, a pair of drive pulleys around which the drive wires are wound, and a drive shaft that fixes the pair of drive pulleys on both sides And driving the drive wires by the rotation of the pair of drive pulleys, moving the carriage, scanning the document surface, and entering the reflected light from the document surface into the image sensor. In an image reading apparatus that reads an image,
The pair of drive pulleys are fixed in the same direction on the drive shaft, and the pair of drive wires are wound around the drive pulleys in the same direction.   The image reading apparatus according to claim 1, wherein the pair of drive wires are formed in the same twist direction.   An image forming apparatus on which the image reading apparatus according to claim 1 is mounted.

Images