JP2008056413A - Sheet feeding device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of stably feeding a sheet and of saving space, and an image formation device. <P>SOLUTION: A first intermittent gear 13 stopped by a first stopping means 17 is rotated in conjunction with the rotation of a second intermittent gear 14 by an interlocking means 18, and geared with a drive gear 12. In addition, after the first intermittent gear 13 is geared with the drive gear 12 in conjunction it with the rotation of the second intermittent gear 14 by the interlocking means 18, the interlocking of the first intermittent gear 13 with the second intermittent gear 14 by the interlocking means 18 is terminated, whereby the first intermittent gear 13 is rotated by the drive gear 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus, and more particularly to a configuration of a driving mechanism that rotates a feeding roller that feeds a sheet.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer that employs an electrostatic recording method or an electrophotographic recording method, a sheet feeding unit that feeds a sheet stored in a sheet storage unit toward an image forming unit by a feeding roller. A feeding device is provided.

  Here, as such a sheet feeding device, for example, the sheet feeding roller is controlled to rotate one rotation by a toothless gear and a trigger member to feed the sheets one by one, and thereafter the sheet is fed by the conveying roller to the image forming unit. (For example, refer to Patent Document 1).

  FIG. 11 is a diagram showing a driving mechanism for driving a feeding roller provided in such a conventional sheet feeding apparatus. Driving from a driving source (not shown) is driven through a front gear 91 to drive gear 92. The drive gear 92 rotates in the direction of the arrow.

  A first segmented gear 93 and a second segmented gear 94 are arranged at the next stage of the drive gear 92. The first toothless gear 93 is fixed to a paper feed shaft 95, and a feed roller 96 for feeding sheets one by one is fixed to the paper feed shaft 95. Cams 97 as first stop means for stopping the first toothless gear 93 at a position where the toothless portion 93 a faces the drive gear 92 are provided at both ends of the paper feed shaft 95 of the feed roller 96. It has been.

  The second toothless gear 94 is rotatably held with respect to the paper feed shaft 95 and the plunger 99a of the solenoid 99 serving as the second stop means is locked, whereby the toothless portion 94a is connected to the drive gear 92. It is designed to stop at the position it faces.

  A spring (not shown) is provided between the second segmented gear 94 and the first segmented gear 93, and the second segmented gear 94 is driven when the latch by the solenoid 99 is released by this spring. It rotates in the direction of meshing with the gear 92.

  Further, a protrusion 101 provided on the first partial gear 93 side and a second partial gear 94 shown in FIG. 12 to be described later are provided between the second partial gear 94 and the first partial gear 93. Interlocking means 98 constituted by the locking holes 94b is provided. The interlocking means 98 rotates the first partial gear 93 while releasing the stop by the cam 97 along with the rotation of the second partial gear 94 by the spring, and meshes with the drive gear 92.

  By providing such a spring and interlocking means 98, when the solenoid 99 is operated, the second segmental gear 94 is rotated by the spring, and the rotation of the second segmental gear 94 is transmitted via the interlocking unit 98 to the first segmental gear 94. This can be transmitted to the toothless gear 93. Note that when the solenoid 99 is operated, the second toothless gear 94 is not fixed to the paper feed shaft 95, so that the load from the paper feed shaft 95 is not received. Can be done with a small force.

  FIG. 12 shows a state before the sheet feeding operation of the drive mechanism is started. At this time, the tip of the plunger 99a of the solenoid 99 is locked, so that the second toothless gear 94 is stopped at a position where the toothless portion 94a faces the drive gear 92. At this time, the first toothless gear 93 is also stopped at a position where the toothless portion 93a faces the drive gear 92 as shown in FIG.

  Further, at this time, the projection 101 provided on the first partial gear 93 stopped by the cam 97 is a second partial gear 94 indicated by an arrow in a locking hole 94b provided in the second partial gear 94. Is in pressure contact with the downstream end in the rotational direction. In this state, the spring disposed between the second partial gear 94 and the first partial gear 93 is in a compressed state.

  Next, when the sheet feeding operation is instructed and the solenoid 99 is operated by this, the locking of the second partial gear 94 by the plunger 99a is released, and accordingly, the second partial gear 94 is moved in the direction of the arrow by the spring. Rotates and meshes with the drive gear 92 as shown in FIG.

  Here, when meshed with the drive gear 92 in this way, the second toothless gear 94 is rotated by the drive gear 92, and the upstream end in the rotational direction of the locking hole 94b provided in the second toothless gear 94 with this rotation. Comes into contact with the protrusion 101 provided on the first toothless gear 93. Thereafter, when the second partial gear 94 further rotates, the rotation of the second partial gear 94 is transmitted to the first partial gear 93 through the protrusion 101.

  Thereby, thereafter, the first toothless gear 93 and the second toothless gear 94 rotate integrally, and as a result, the feeding roller 96 rotates. After that, when the feed roller 96 makes one rotation, the cam 97 stops the first toothless gear 93 at a position where the toothless portion 93a faces the driving gear 92. Thereafter, the second toothless gear 94 is stopped by the solenoid 99 at a position where the toothless portion 94a faces the drive gear 92 as shown in FIG.

JP-A-10-153247

  By the way, in such a conventional sheet feeding apparatus and image forming apparatus, when the first missing gear 93 and the second missing gear 94 rotate integrally, the first missing gear 93 and the second missing gear are rotated. The gears 94 are configured so that the teeth have the same phase. As a result, the first partial gear 93 is smoothly meshed with the drive gear 92.

  However, the phase of the teeth of the first toothless gear 93 and the second toothless gear 94 may be shifted in either the rotational direction or the counter-rotating direction depending on the dimensional accuracy and mounting accuracy of each component. FIG. 14 shows a state in which the phase of the teeth of the first segmented gear 93 and the second segmented gear 94 is slower in the second segmented gear 94, that is, the first segmented gear 93 is rotating in advance. Is shown.

  When the first partial gear 93 rotates in this state, the first partial gear 93 meshes with the drive gear 92 later than the second partial gear 94 as shown in FIG. Here, even when the phase of the teeth is shifted in this way, the first partial gear 93 is smoothly meshed with the drive gear 92 as long as the phase difference is not greatly different.

  However, as shown in FIG. 15, when the first toothless gear 93 is rotated in advance, only the second toothless gear 94 actually meshes with the driving gear 92, and the driving gear 92 is the second toothless gear. A rotational force is continuously applied only to the gear 94. As a result, the rotational force is transmitted to the first partial gear 93 from the second partial gear 94 via the interlocking means 98.

  As described above, when the rotational force from the drive gear 92 is not directly transmitted to the first segmented gear 93 via the second segmented gear 94 and the interlocking means 98, the first and second segmented gears 93 are transmitted. , 94 and the feeding shaft 95, the sum of the mounting gaps and component tolerances generated at the mounting portion. As a result, smooth drive transmission is hindered and drive transmission accuracy is lowered, and stable sheet feeding cannot be performed.

  When the phase of the first toothless gear 93 and the second toothless gear 94 is shifted, the driving force from the driving gear 92 is fed to one of the first and second toothless gears 93, 94 by one. It is transmitted to the shaft 95. That is, when the phases of the first and second segmented gears 93 and 94 are shifted, the driving force from the drive gear 92 is fed to one of the first and second segmented gears 93 and 94 via one of them. It is transmitted to the roller 96 (paper feed shaft 95).

  Therefore, when designing the drive mechanism having the above-described configuration, it is necessary to have the same strength so that either of the first and second toothless gears 93 and 94 may be used. As a result, as the first and second toothless gears 93 and 94, two identical gears having the strength required for design, for example, the tooth width, must be arranged, which is an obstacle to space saving.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet feeding apparatus and an image forming apparatus that can stably feed a sheet and save space. is there.

  The present invention provides a sheet feeding apparatus including a feeding roller for feeding a sheet, a driving gear for rotating the feeding roller, a first partial gear fixed to a shaft of the feeding roller, A second toothless gear rotatably held on the shaft of the feed roller; first stopping means for stopping the first toothless gear at a position where the toothless portion faces the drive gear; and the second toothless gear. A second stop means for stopping the toothed gear at a position where the tooth missing portion faces the drive gear; and when the stop operation by the second stop means is released, the second toothless gear is rotated to move the drive gear. A rotating means that meshes with the driving gear, and a rotation mechanism that meshes with the driving gear by rotating the first missing gear that is stopped by the first stopping means in conjunction with the rotation of the second missing gear by the rotating means. Means, and the interlocking means is the first missing tooth Until the engagement with the drive gear, the interlocking means is rotated in conjunction with the rotation of the second intermittent gear, and after the engagement with the drive gear, the interlocking by the interlocking means is released and the drive gear is used. It is configured to rotate.

  According to the present invention, the first segmented gear is rotated in conjunction with the rotation of the second segmented gear until meshed with the drive gear, and after meshing with the drive gear, the first segmented gear is coupled with the second segmented gear. By releasing and rotating by the drive gear, stable sheet feeding and space saving can be achieved.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

  FIG. 1 is a diagram showing a schematic configuration of a laser beam printer which is an example of an image forming apparatus provided with a sheet feeding apparatus according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a laser beam printer capable of forming images on both sides of a sheet. The laser beam printer 1 includes a laser beam printer main body 1A and an image forming unit 1B for forming an image. Further, after the image is formed on the first side, the sheet feeding unit 1C that feeds the sheet S to the image forming unit 1B again to form an image on the second side (back side) and the image forming unit 1B. A sheet feeding device 1D for separating and feeding the sheets S one by one is provided.

  Here, the image forming unit 1B includes a process cartridge 6, a transfer roller 9, and the like. The sheet feeding apparatus 1D includes a sheet feeding cassette 2 that is a sheet storing unit that stores the sheet S, and a sheet S stored in the sheet feeding cassette 2. A feeding roller 16 is provided.

  The process cartridge 6 is integrally provided with a photosensitive drum 7 and process means (charging means, developing means, cleaning means) that act on the photosensitive drum 7, and is detachable from a laser beam printer main body (hereinafter referred to as printer main body) 1A. ing. In FIG. 1, 8 is a laser scanner unit, 23 is a fixing unit as a fixing unit, and 27 is a sheet discharge stacking base.

  Next, an image forming operation of the laser beam printer 1 configured as described above will be described.

  When image information is sent from a personal computer (not shown) and a control unit (not shown) that performs image formation processing of this image information issues a print command, it is loaded on a paper feed cassette 2 that is detachably attached to the printer body 1A. The sheet S is fed by the feeding roller 16. Thereafter, the sheets S are separated one by one by a separation unit constituted by the feeding roller 16 and the separation pad 30, and then conveyed to the registration roller pair 22 through the conveyance roller 31 to correct skewing. Further, after the skew is corrected by the registration roller pair 22 in this way, the sheet S is sent to a transfer portion constituted by a nip between the photosensitive drum 7 and the transfer roller 9 in the process cartridge.

  On the other hand, laser light having the image information converted into a bit image is irradiated on the photosensitive drum based on the image information together with the print command, and a latent image is formed on the surface of the photosensitive drum 7 in accordance with the bit image. Further, by developing this latent image, a toner image is formed on the photosensitive drum.

  The toner image formed on the photosensitive drum in this way is transferred to the sheet S sent to the transfer portion by the registration roller pair 22. Further, the sheet S to which the toner image has been transferred is thereafter sent to the fixing unit 23 and is heated and pressed by the fixing unit 23 so that the toner image is fixed semi-permanently.

  The sheet S that has passed through the fixing unit 23 is sent to the first nip N <b> 1 between the fixing discharge roller 24 and the first roller 25. In the case where an image is formed only on the first surface of the sheet S, it is then sent to the discharge roller pair 32 and discharged to the sheet discharge stack 27 by the discharge roller pair 32.

  On the other hand, when images are formed on both sides of the sheet S, the sheet S first passes through the first nip N1 of the fixing discharge roller 24, and then faces the sheet discharge stack 27 by the normal discharge roller pair 32. Are transported. Thereafter, when the trailing edge of the sheet passes through the first nip N1, the discharge roller pair 32 temporarily stops and then reverses.

  As a result, the sheet S enters the second nip N2 formed by the fixing discharge roller 24 and the second roller 26 with the rear end of the leading edge reversed, and thereafter, the sheet S is nipped and conveyed by the fixing discharge roller 24 and the second roller 26. Then, the paper enters the paper refeeding section 1C.

  Next, the sheet S is sent to the transfer section through the registration roller pair 22 by the refeed roller 27 provided in the refeed conveyance section 1C, and the toner image formed on the photosensitive drum is transferred. Thereafter, the sheet S passes through the fixing unit 23, the first nip N <b> 1 between the fixing discharge roller 24 and the first roller 25, and then is discharged onto the sheet discharge stack 27 by the discharge roller pair 32.

  FIG. 2 is a perspective view showing the configuration of the sheet feeding apparatus 1D. In FIG. 2, reference numeral 20 denotes a driving mechanism that drives the feeding roller 16. The drive mechanism 20 includes a front gear 11 that is rotated by a drive source (not shown), a drive gear 12 that is rotated by the front gear 11, a first intermittent gear 13 and a second partial gear that mesh with the drive gear 12 at a predetermined timing. A tooth gear 14 is provided.

  The first partial gear 13 is fixed to a paper feed shaft 15, and a feed roller 16 for feeding sheets one by one is fixed to the paper feed shaft 15. Further, cams 17 as first stop means for stopping the first toothless gear 13 at a position where the toothless portion 13 a faces the drive gear 12 are provided at both ends of the paper feed shaft 15.

  Here, in the present embodiment, the cam 17 is provided in the paper feed cassette 2 so as to be rotatable in the vertical direction as shown in FIG. 3, and is urged upward by a spring 2b (see FIG. 1). It is in contact with the middle plate 2a. When the cam 17 is rotated by the rotation of the feeding roller 16, the contact with the intermediate plate 2a is released, and accordingly, the intermediate plate 2a rotates upward and moves to a position where the sheet is pressed against the feeding roller 16. To do.

  Thereafter, when the sheet is fed out by one rotation of the feeding roller 16, the cam 17 comes into contact with the intermediate plate 2a from above, and accordingly, the intermediate plate 2a rotates downward and moves to the position shown in FIG. When the intermediate plate 2a is rotated downward in this manner, the cam 17 is pressed by the spring 2b urging the intermediate plate 2a and is prevented from moving downward. As a result, the first toothless gear 13 fixed to the paper feed shaft 15 together with the cam 17 stops at a position where the toothless portion 13 a faces the drive gear 12.

  The second toothless gear 14 is rotatably supported with respect to the paper feed shaft 15 and the plunger 19a of the solenoid 19 serving as the second stop means is locked, whereby the toothless portion 14a is connected to the drive gear 12. It stops at the position where it faces.

  A spring (not shown) which is a rotating means is provided between the second partial gear 14 and the first partial gear 13, and when the locking by the solenoid 19 is released by this spring, the second partial gear The gear 14 rotates in a direction to mesh with the drive gear 12.

  Further, a projection 21 as a pressed portion provided on the first segmental gear 13 side between the second segmental gear 14 and the first segmental gear 13 and a second segmental gear shown in FIG. 4 to be described later. Interlocking means 18 constituted by a locking hole 14 b which is a pressing portion provided in 14 is provided. The interlocking means 18 rotates the first toothless gear 13 in mesh with the drive gear 12 while releasing the stop by the cam 17 in conjunction with the rotation of the second toothless gear 14 by the spring.

  By providing such a spring and interlocking means 18, when the solenoid 19 is operated, the second partial gear 14 is rotated by the spring, and the rotation of the second partial gear 14 is rotated via the interlocking means 18. This can be transmitted to the toothless gear 13. Note that when the solenoid 19 is operated, the second toothless gear 14 is not fixed to the paper feed shaft 15, so that the load from the paper feed shaft 15 is not received. It can be done with a small force.

  FIG. 4 shows a state before the sheet feeding operation is started. At this time, the tip of the plunger 19 a of the solenoid 19 is locked, so that the second toothless gear 14 is stopped at a position where the toothless portion 14 a faces the drive gear 12. At this time, the first toothless gear 13 is also stopped at a position where the toothless portion 13a faces the drive gear 12, as shown in FIG.

  At this time, the protrusion 21 provided on the first partial gear 13 stopped by the cam 17 is a second partial gear 14 indicated by an arrow in a locking hole 14b provided in the second partial gear 14. Is in pressure contact with the downstream end in the rotational direction. In this state, the spring disposed between the second partial gear 14 and the first partial gear 13 is in a compressed state.

  Next, when the sheet feeding operation is instructed and the solenoid 19 is operated thereby, the locking of the second partial gear 14 is released, and accordingly, the second partial gear 14 is rotated in the direction of the arrow by the spring, As shown in FIG. 5, it meshes with the drive gear 12.

  Here, when meshed with the drive gear 12 in this way, the second toothless gear 14 is rotated by the drive gear 12, and the rotation direction upstream side of the locking hole 14b provided in the second toothless gear 14 with this rotation. The end comes into contact with the protrusion 21 provided on the first partial gear 13. Thereafter, when the second partial gear 14 further rotates, the rotation of the second partial gear 14 is transmitted to the first partial gear 13 through the protrusion 21.

  As a result, the first toothless gear 13 rotates integrally with the second toothless gear 14 via the interlocking means 18 in conjunction with the rotation of the second toothless gear 14, and as a result, the feeding roller 16 rotates. To do. After this, when the feed roller 16 makes one rotation, the cam 17 stops the first toothless gear 13 at a position where the toothless portion 13 a faces the drive gear 12. Thereafter, the second toothless gear 14 is stopped by the solenoid 19 at a position where the toothless portion 14 a shown in FIG. 4 faces the drive gear 12.

  By the way, in this embodiment, as shown in FIG. 5, the interlocking means 18, the first partial gear 13, and the second partial gear 14 are attached so that the second partial gear 14 rotates in advance. The position is set.

  As a result, when the first and second partial gears 13 and 14 mesh with the drive gear 12, the first partial gear 13 is initially moved by the amount that the second partial gear 14 precedes as shown in FIG. 5. It meshes with the drive gear 12 and rotates. Since the second partial gear 14 is rotatably held on the paper feed shaft 15, the second partial gear 14 does not rotate even if the first partial gear 13 rotates.

  When the first partial gear 13 rotates in this way, specifically, when the phase difference between the second partial gear 14 and the second partial gear 14 rotates, the first partial gear 13 and the second partial gear as shown in FIG. The phases of the 14 teeth are the same, and then the first and second toothless gears 13 and 14 rotate together.

  Here, when the second segmented gear 14 that precedes the first segmented gear 13 becomes in phase with the first segmented gear 13 in this way, the second segmented gear 14 is the first segmented gear 14. The rotation is returned to the opposite side relative to the first partial gear 13 by an angle that precedes the partial gear 13. As a result, as shown in FIG. 6, a gap g is generated between the protrusion 21 provided on the first partial gear 13 and the locking hole 14 b provided on the second partial gear 14.

  Then, when the gap g is generated between the projection 21 and the locking hole 14b in this way, the interlocking of the first partial gear 13 with respect to the second partial gear 14 by the interlocking means 18 is released, and the first The rotation of the two-tooth gear 14 is not transmitted to the first tooth-missing gear 13. As a result, the first partial gear 13 is directly driven by the drive gear 12. That is, in the state where the first and second partial gears 13 and 14 are simultaneously meshed with the drive gear 12, rotation transmission from the second partial gear 14 to the first partial gear 13 does not occur, and the drive The rotation of the gear 12 is directly transmitted to the first partial gear 13.

  In this way, when the rotation of the drive gear 12 is directly transmitted to the first toothless gear 13, when the first and second toothless gears 13 and 14 are attached to the paper feeding shaft 15, the paper feeding shaft 15 The sum of mounting gaps and component tolerances generated between the two can be minimized. Accordingly, smooth drive transmission can be realized, and stable sheet feeding can be performed.

  Further, at the initial stage of rotation of the second toothless gear 14, the second toothless gear 14 rotates the first toothless gear 13 via the interlocking means 18. In this state, the feeding roller 16 is still on the sheet, There is no contact. For this reason, the strength of the teeth required for the second toothless gear 14 is such that the stopping operation of the cam 17 can be canceled with respect to the first toothless gear 13 which is smaller than the force required for feeding the sheet. Anything that can transmit power is acceptable. For this reason, the required tooth width of the drive gear 12 can be reduced, and as a result, the sheet feeding apparatus 1D can be made compact and space-saving.

  As described above, in the present embodiment, after the first partial gear 13 is meshed with the drive gear 12 in conjunction with the rotation of the second partial gear 14, the first partial gear with respect to the second partial gear 14 is obtained. The interlocking of the gear 13 is released, and the first gear 13 is rotated by the drive gear 12. As a result, it is possible to provide a sheet feeding apparatus 1D capable of stable sheet feeding and space saving, and a laser beam printer 1 (image forming apparatus) including the sheet feeding apparatus 1D.

  In the present embodiment, the phase difference is estimated to be about one-third or less of the gear pitch, and even when the first and second partial gears 13 and 14 are provided with the phase difference, the first difference is expected. The tooth tips do not collide with each other when the partial gear 13 is engaged with the drive gear 12.

  Next, a second embodiment of the present invention will be described.

  FIG. 7 is a perspective view showing the configuration of the sheet feeding apparatus according to the present embodiment. 7, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

  In FIG. 7, reference numeral 52 denotes a tapered drive gear which is a drive gear to which rotation from a drive source is transmitted via the front gear 11, and the tapered drive gear 52 is engaged with the first intermittent gear 13. A tooth portion 52 a and a second tooth portion 52 b that meshes with the second partial gear 14 are provided. In addition, 52d is a shaft of the tapered drive gear 52, and 11a is a shaft of the front gear 11.

  Here, the second tooth portion 52b of the tapered drive gear 52 has a tapered surface 52c on the upstream side in the rotational direction as shown in FIG. 8, specifically, the rotational direction from the tooth root side of the side surface on the upstream side in the rotational direction. An inclined surface cut out toward the downstream tooth tip side is formed. Then, by forming the tapered surface (inclined surface) 52c in the second tooth portion 52b in this way, the tooth tip of the second intermittent gear 14 and the tooth tip of the tapered drive gear 52 are smoothly meshed with each other without colliding. It is supposed to do.

  As a result, when the second intermittent gear 14 and the tapered drive gear 52 are meshed, smoother meshing can be realized, and more stable sheet feeding can be performed.

  Next, a third embodiment of the present invention will be described.

  FIG. 9 is a top view of a drive mechanism provided in the sheet feeding apparatus according to the present embodiment. 9, the same reference numerals as those in FIG. 7 indicate the same or corresponding parts.

  As shown in FIG. 9, in the present embodiment, the first partial gear 13 having the largest load during the sheet feeding operation, the first tooth portion 52a without the taper of the tapered drive gear 52, and the front stage The gear 11 is arranged in a row.

  Then, by arranging the first toothless gear 13, the first tooth portion 52 a of the tapered drive gear 52, and the front gear 11 in a row in this way, the torsional force of the tapered drive gear 52 in the radial direction is increased. The backlash between the gears can be kept optimal.

  Next, a fourth embodiment of the present invention will be described.

  FIG. 10 is a top view of a drive mechanism provided in the sheet feeding apparatus according to the present embodiment. In FIG. 10, reference numeral 81 denotes a cam provided on the second partial gear 14, and this cam 81 is provided between the first partial gear 13 and the second partial gear 14. In this embodiment, the cam 81 is locked to the plunger 29a of the solenoid 29 so that the second toothless gear 14 is stopped at a position where the toothless portion faces the tapered driving gear 52. ing.

  Here, the width of the cam 81 is largely dependent on the width of the plunger 29a of the solenoid 29, and compared with the width of the cam 81, the component accuracy and the axial position accuracy of the tapered drive gear 52 are small. Therefore, accuracy is not required for the joint between the first tooth portion 52a and the second tooth portion 52b of the tapered drive gear 52, and the dimensional accuracy of the joint of the tapered drive gear 52 can be relaxed.

  Further, by disposing the cam 81 between the two toothless gears 13 and 14, the solenoid 29 can be arranged in parallel with the toothless gears 13 and 14, and the axial size can be reduced to the two toothless gears. It can be accommodated between the gears 13 and 14. As a result, the drive mechanism can be made compact, and the present invention can be employed even in products that require space saving and compactness.

1 is a diagram illustrating a schematic configuration of a laser beam printer which is an example of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention. FIG. 3 is a perspective view illustrating a configuration of the sheet feeding device. The perspective view explaining the effect | action of the cam provided in the said sheet | seat feeding apparatus. FIG. 4 is a diagram illustrating a state before a sheet feeding operation of a driving mechanism that drives a feeding roller provided in the sheet feeding apparatus is started. The figure which shows the state after the sheet | seat feeding operation | movement of the said drive mechanism was instruct | indicated. The figure which shows a state when the 1st missing-tooth gear of the said drive mechanism and the 2nd missing-tooth gear mesh | engaged with the driving gear. The perspective view which shows the structure of the sheet feeding apparatus which concerns on the 2nd Embodiment of this invention. FIG. 4 is a diagram illustrating a configuration of a driving mechanism that drives a feeding roller provided in the sheet feeding apparatus. FIG. 10 is a top view of a drive mechanism provided in a sheet feeding apparatus according to a third embodiment of the present invention. FIG. 10 is a top view of a drive mechanism provided in a sheet feeding device according to a fourth embodiment of the present invention. FIG. 6 is a diagram illustrating a driving mechanism that drives a feeding roller provided in a conventional sheet feeding apparatus. The figure which shows the state before the sheet feeding operation | movement of the said drive mechanism is started. The figure which shows the state after the sheet | seat feeding operation | movement of the said drive mechanism was instruct | indicated. The figure which shows the state which the phase of the tooth | gear of a 1st segmented gear of the 1st segmented gear of the said drive mechanism and a 2nd segmented gear rotates ahead. Operation | movement explanatory drawing of the state which the phase of the tooth | gear of the 1st segmented gear of the 1st segmented gear of the said drive mechanism and the 2nd segmented gear rotates ahead.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam printer 1B Image formation part 1D Sheet feeding apparatus 2 Paper feed cassette 11 Front stage gear 12 Drive gear 13 First partial gear 14 Second partial gear 14a Partial gear 14b Locking hole 15 Paper feed shaft 16 Feed Roller 17 Cam 18 Interlocking means 19 Solenoid 20 Drive mechanism 21 Projection 52 Tapered drive gear 52a First tooth portion 52b Second tooth portion 81 Cam S Sheet

Claims (8)

In a sheet feeding apparatus having a feeding roller for feeding out a sheet,
A driving gear for rotating the feeding roller;
A first toothless gear fixed to the shaft of the feeding roller;
A second intermittent gear held rotatably on the shaft of the feed roller;
First stop means for stopping the first toothless gear at a position where the toothless portion faces the drive gear;
Second stop means for stopping the second toothless gear at a position where the toothless portion faces the drive gear;
Rotating means for rotating the second toothless gear and meshing with the drive gear when the stopping operation by the second stopping means is released;
Interlocking means for rotating the first segmented gear stopped by the first stopping means in conjunction with the rotation of the second segmented gear by the rotating means and meshing with the drive gear;
The interlocking means is rotated by the interlocking means in conjunction with the rotation of the second intermittent gear until the first intermittent gear meshes with the drive gear, and after the interlocking with the drive gear, the interlocking is performed. The sheet feeding device is configured to release the interlocking by the means and rotate by the driving gear. The interlocking means is provided in the pressed portion provided in the first partial gear and the second partial gear, and the pressed portion is moved in the first partial portion as the second partial gear rotates. A pressing portion that presses the toothed gear in the direction of rotation,
2. The sheet feeding device according to claim 1, wherein the interlocking unit is configured to release the pressing of the pressed portion by the pressing portion after the first intermittent gear meshes with the driving gear. 3. Feeding device.   The first toothless gear and the second toothless gear have teeth of the same phase, and after the first toothless gear meshes with the drive gear, the pressing portion presses the pressed portion. The phase of the second toothless gear is shifted to the downstream side in the rotational direction compared to the first toothless gear so as to be released, and after meshing with the drive gear, the phase difference from the second toothless gear is the same. The sheet feeding apparatus according to claim 2, wherein only the first toothless gear is rotated.   4. An inclined surface notched from a tooth base side on the side surface on the upstream side in the rotational direction to a tooth tip side on the downstream side in the rotational direction is formed on the teeth of the drive gear. The sheet feeding apparatus according to claim 1. The drive gear is provided with a first tooth portion that meshes with the first partial gear, and a second tooth portion that meshes with the second partial gear,
The sheet feeding device according to claim 4, wherein the inclined surface is formed on a tooth of the second tooth portion.   The sheet feeding device according to any one of claims 1 to 5, wherein the driving gear, a front gear for driving the driving gear, and the first partial gear are arranged in a line.   The sheet feeding device according to any one of claims 1 to 6, wherein the second stopping means is disposed between the first segmented gear and the second segmented gear. An image forming apparatus comprising: an image forming unit; and the sheet feeding device according to claim 1 for feeding a sheet to the image forming unit.

Images