JP2009062114A - Sheet supply device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet supply device for reducing a load ranging from rack teeth to a driving motor while securing positioning stop accuracy at a lowering position of a sheet stacking member without adding a new mechanism component such as a torque limiter. <P>SOLUTION: The formation range of a rack gear 12a of a rack plate 12A is set so that a cassette side input gear 8 is idled at a moving position of the rack plate 12A where an intermediate plate 2 is lowered. When the intermediate plate 2 gets to a lowering position, the cassette side input gear 8 is idled relative to the rack gear 12a to give no overload to a drive mechanism ranging from the rack gear 12a to a lifter motor 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sheet supply apparatus that stacks a sheet bundle on a sheet cassette that can be pulled out from the apparatus main body and supplies the uppermost sheet to an image forming unit or the like, and more particularly to a structure that lifts the sheet bundle on the sheet delivery side. The present invention also relates to an image forming apparatus including a sheet supply device.

  A sheet supply apparatus that stacks a sheet bundle on a sheet stacking member of a sheet cassette that can be pulled out from the apparatus main body, raises the sheet stacking member, and brings the uppermost sheet into contact with the sheet supply member on the apparatus main body side. It has been put into practical use.

  Patent Document 1 discloses an image forming apparatus that incorporates such a sheet supply apparatus and supplies a sheet to an image forming unit that performs electrophotographic image formation. Here, a rack member is formed on the side wall portion opposite to the drawing direction of the sheet cassette to be pulled out to the front side (back side), and a rack member movable in the direction along the side wall portion, and a pinion meshed with the rack teeth Members are arranged.

  In addition, an attachment / detachment drive mechanism that connects the drive mechanism on the apparatus main body side to the pinion member in conjunction with the operation of pushing the sheet cassette into the apparatus main body is disposed in the apparatus main body. Then, the driving force transmitted to the pinion member is detected on the apparatus main body side by detecting the raised position of the sheet stacking member, so that the uppermost sheet of the sheet bundle comes into contact with the sheet feeding member with a predetermined range of pressure. It has become.

  Further, the sheet stacking member is rotated with respect to the bottom surface of the sheet cassette to raise and lower the sheet delivery side. Connected by paper pressure spring.

Japanese Patent Application Laid-Open No. 2006-56885

  In the sheet supply device of Patent Document 1, when the stop of the driving force is delayed when the sheet stacking member is lowered, the sheet stacking member hits the lowering limit, and a large load is applied to the rack teeth. Even when the lowering limit is not reached, at the time of sudden lowering stop, the weight of the sheet bundle is added and a large inertia force is transmitted from the rack teeth to the drive mechanism on the apparatus body side via the pinion gear, and goes back to the drive motor shaft. All transmission members were heavily loaded.

  Therefore, it has been proposed that the driving force is gradually reduced and stopped long before the sheet stacking member reaches the lowering limit, but in this case, it is difficult to accurately stop the positioning of the sheet stacking member to the lowering limit. . With a combination of an inexpensive drive motor and a simple control circuit, there is a possibility that the lowering position is moved back and forth each time depending on the weight of the sheet bundle stacked on the sheet stacking member.

  In addition, it has been proposed to limit the torque transmitted to the pinion member by providing a torque limiter on the apparatus main body side. However, in this case, the parts cost of the torque limiter is increased, and it is difficult to secure an arrangement space.

  The present invention provides a sheet supply apparatus that can secure a positioning stop accuracy at a lowered position of a sheet stacking member and reduce a load from a rack tooth to a drive motor without adding a new mechanism component such as a torque limiter. The purpose is that.

  The sheet supply apparatus according to the present invention includes a sheet cassette having a sheet stacking member that can be moved up and down on which a sheet bundle is stacked and can be pulled out from the apparatus main body, and an uppermost surface of the sheet bundle stacked on the sheet stacking member. A sheet supply member that feeds out the sheet from the sheet cassette, a rack member that is formed with rack teeth and reciprocates in a direction along the side wall, and is arranged so as to be able to mesh with the rack teeth and rotates to rotate the rack. A pinion member that reciprocates the member, and a support lever portion that is rotatably arranged and pushes up the sheet stacking member in accordance with the movement of the rack member, and the rack member that has lowered the sheet stacking member The rack member is provided with an idling portion for reducing the driving force transmission performance of the rack teeth so that the pinion member idles at the moving position. There.

  In the sheet feeding apparatus of the present invention, in the ascending process and descending process of the sheet stacking member, the rack teeth of the rack member and the pinion member normally mesh with each other to perform 100% power transmission.

  However, at the lowered position of the sheet stacking member, the rack member and the pinion member function as a torque limiter that operates only at the position of the limited idling portion, thereby limiting the torque transmitted from the rack teeth to the pinion member. Only the transmission torque at the lowered position (idling portion) of the sheet stacking member is set to a small value (including 0) without affecting the transmission torque in the ascending process and the descending process.

  Therefore, the positioning stop accuracy at the lowered position of the sheet stacking member can be ensured without adding new mechanism parts such as a torque limiter, and the load from the rack teeth to the drive motor can be reduced.

  Embodiments of the present invention will be described in detail with reference to the drawings. The present invention can be applied to another embodiment in which part or all of the configuration of the embodiment is replaced as long as the rack member that reciprocates along the side wall portion of the sheet cassette is driven by the pinion member to raise and lower the sheet stacking member. It can be implemented.

  The sheet supply device may be configured independently and disposed at the lower or upstream side of the image forming apparatus, or may be integrated into the housing of the image forming apparatus.

  The image forming apparatus may be distinguished between monochrome and full color, electrophotographic method, inkjet method, and other printing methods.

  The general matters of the image forming apparatus and the sheet supply apparatus disclosed in Patent Document 1 are not illustrated and redundant description is omitted.

<First Embodiment>
1 is a perspective view of the appearance of the image forming apparatus, FIG. 2 is an explanatory diagram of the configuration of the image forming apparatus, FIG. 3 is a plan view of the sheet cassette, and FIG. 4 is a perspective view of the lifting drive mechanism for the middle plate as viewed from above. is there. In FIG. 1, (a) is a pushed-in state of the sheet cassette, and (b) is a pulled-out state of the sheet cassette.

  As shown in FIG. 1A, in the image forming apparatus 100 with a built-in sheet supply device, the sheet cassette 1 can be pulled out from the apparatus main body 101 to the front side, and a sheet bundle can be stacked from above the sheet cassette 1. .

  As shown in FIG. 1B, the sheet bundle stacked on the sheet cassette 1 is pulled out one sheet at a time from the top surface in the direction of the arrow, and is fed to the apparatus main body 101 of the image forming apparatus 100. The sheet on which the image is formed by the apparatus main body 101 is discharged to the upper discharge tray 103 through the discharge unit 104.

  As shown in FIG. 2, the intermediate plate 2 on which the sheet bundle PB is stacked rotates with respect to the sheet cassette 1 and pushes up the sheet P delivery side of the sheet bundle PB. The intermediate plate 2 is pushed up by the rotation of the pressing lever 21.

  The control unit 120, which is an example of a control unit, rotates the lifter motor 4 to rotate the pressing lever 21 until a predetermined contact pressure is detected by the contact pressure detection unit 121.

  As a result, the uppermost surface of the sheet bundle PB stacked on the intermediate plate 2 contacts the sheet feeding roller 111 on the apparatus main body 101 side with a predetermined range of contact pressure, and the uppermost surface of the sheet bundle PB is rotated along with the rotation of the sheet feeding roller 111. The sheet P is sent out to the apparatus main body 101.

  When the intermediate plate 2 is lowered, the control unit 120 reverses and lifts the lifter motor 4 for a predetermined time. The fixed time is set to an average time for lowering the lift position from the highest position to the lowest position. Further, when an overcurrent flows through the lifter motor 4, the control unit 120 stops the lifter motor 4 regardless of the lift position in order to avoid an overload of the lift mechanism of the intermediate plate 2 including the lifter motor 4.

  Instead of providing the contact pressure detection unit 121, a predetermined contact pressure may be obtained by rotating the lifter motor 4 by a predetermined amount and moving a rack plate 12 described later by a predetermined amount. Further, as shown in Patent Document 1, a control for operating / stopping the lifter motor 4 by setting the movement position of the rack plate 12 described later in a plurality of stages according to the basis weight (weight) of the sheet is adopted. May be.

  In addition, a distance sensor that detects the uppermost surface of the sheet bundle PB stacked on the intermediate plate 2 may be provided, and control for operating / stopping the lifter motor 4 to a height position where the distance sensor detects a predetermined distance may be adopted. Good.

  In any case, the sheet feeding roller 111 rotates in contact with the sheet bundle PB, pulls out the uppermost sheet P, separates the sheet P from the friction plate 112 one by one, and supplies it to the registration roller 113. To feed.

  The registration roller 113 receives the sheet P in the stopped state and corrects the skew feeding, and then supplies the sheet P to the nip between the photosensitive drum 115 and the transfer roller 116 in synchronization with the toner image formed on the photosensitive drum 115. To send.

  The system cartridge 110, which is an example of an image forming unit, includes a charging device, a developing device, a cleaning device, and the like disposed therein as a unit together with the photosensitive drum 115, and can be taken out from the apparatus main body 101 and replaced.

  The photosensitive drum 115 uniformly charged by the charging device is scanned and exposed by the exposure device 119 to form an electrostatic image of the image, and then black toner is attached to the electrostatic image to form a monochrome image toner image. The

  The toner image formed on the photosensitive drum 115 as an example of the image forming unit is transferred to the sheet P fed by the registration roller 113 by applying a voltage having a polarity opposite to the charging polarity of the toner image to the transfer roller 116. Is done.

  In the process of passing through the nip of the fixing device 117, the toner image transferred to the sheet P is compressed flatly while being melted by being heated and pressurized, and is fixed on the surface of the recording material P.

  The sheet P on which the toner image is fixed is conveyed to the discharge roller 118 and discharged to the discharge tray 103 through the discharge unit 104.

  A manual feed tray 102 is arranged on the right side surface of the apparatus main body 101. It is also possible to form an image in the same manner by placing a sheet on the manual feed tray 102 and feeding the sheet to the registration roller 113. .

  As shown in FIG. 3, the middle plate 2, which is an example of a sheet stacking member, is restrained by a hinge 22 that is disposed substantially at the center of the sheet cassette 1, so that the sheet feeding side can be rotated to move up and down. is there.

  The wide pressing lever 21 is turned upright with the edge on the rear end side of the sheet bundle as a fulcrum, supports the intermediate plate 2 at the edge on the front end side of the sheet bundle, and depends on the rotation position. 2 is moved up and down in a direction perpendicular to the paper surface.

  Since the rack plate 12 and the cassette-side input gear 8 are assembled on the side wall portion of the sheet cassette 1, the rack plate 12 and the cassette-side input gear 8 move together with the sheet cassette 1 in the direction of the arrow b and are pulled out to the front side of the apparatus main body 101.

  On the apparatus main body 101 side, a lifter motor 4, a first gear 5, a second gear 6, and a third gear 7 are arranged as a main body side drive train 3 that rotates the pressing lever 21 to raise and lower the intermediate plate 2. .

  The third gear 7, which is an example of an attaching / detaching drive mechanism, is attached so as to be slidable in the axial direction while maintaining meshing with the second gear 6, and is moved toward the sheet cassette 1 by an unillustrated urging spring. It is energized.

  In the process of moving the sheet cassette 1 in the direction of arrow b and pulling it out from the apparatus main body 101, the meshing of the third gear 7 and the cassette side input gear 8 slides, and the meshing of both is smoothly released.

  In the process of moving the sheet cassette 1 in the direction opposite to the arrow b and pushing it into the apparatus main body 101, even if the third gear 7 and the cassette-side input gear 8 do not mesh smoothly, the third gear 7 moves backward and the sheet cassette Does not obstruct the pushing of 1. Thereafter, when the third gear 7 starts to rotate, the third gear 7 meshes with the cassette-side input gear 8, and the third gear 7 moves to a normal meshing position on the sheet cassette 1 side.

  When the sheet cassette 1 is moved in the direction opposite to the arrow b and inserted into the apparatus main body 101, the control unit (120: FIG. 2) detects the sheet cassette 1 based on the output of a sensor (not shown). Prior to the start of image formation, the control unit (120: FIG. 2) rotates the lifter motor 4 forward and rotates the cassette input gear 8 via the main body side drive train 3, whereby the rack plate 12 is illustrated. The sheet bundle (PB: FIG. 2) is raised by moving in the middle left direction.

  When the image forming job is completed or the sheet runs out during the job processing, the control unit (120: FIG. 2) rotates the lifter motor 4 in the reverse direction to move the rack plate 12 to the right in the drawing. The sheet bundle (PB: FIG. 2) is lowered.

  As shown in FIG. 4, the rotation of the lifter motor 4 rotates the first gear 5 via the worm gear 4a, and the decelerated rotation moves from the second gear 6 to the sheet gear 1 via the third gear 7. It is transmitted to the cassette side input gear 8 arranged on the side. The meshing between the worm gear 4a and the first gear 5 prevents the middle plate 2 on which the sheet bundle is stacked from falling by its own weight when the lift motor 4 is stopped.

  The intermediate plate cam 11 and the pressing lever 21, which are examples of the support lever portion, are disposed so as to be rotatable with respect to the sheet cassette 1.

  Since the intermediate plate cam 11 is fixed to one end of the pressing lever 21, the intermediate plate cam 11 rotates integrally with the pressing lever 21 to push up the rotating end of the intermediate plate 2, that is, the sheet take-out side.

  A paper feed pressure spring 10 that is an example of a spring means is disposed between a rotating end of the intermediate plate cam 11 and an arm portion 12b of a rack plate 12 that is an example of a rack member.

  The rack plate 12 is restricted in movement and rotation in the height direction by the guides 9a and 9b, and can reciprocate in the direction along the side wall portion of the sheet cassette 1, that is, in the sheet feeding direction (P: FIG. 2). Yes (see FIG. 10).

  A rack gear 12a, which is an example of a rack tooth, is formed on the upper surface of the rack plate 12, and a cassette side input gear 8, which is an example of a pinion member, meshes with the rack gear 12a.

<Reference Example 1>
FIG. 5 is an explanatory diagram of the configuration of the sheet feeding apparatus of Reference Example 1, FIG. 6 is an explanatory diagram of the state where the sheet bundle in Reference Example 1 is lowered, and FIG. 7 is an explanation of the state where the sheet bundle is raised in Reference Example 1. FIG.

  As shown in FIG. 5, the rotation of the lifter motor 4 rotates the first gear 5 via the worm gear 4a. The rotation of the first gear 5 is transmitted from the second gear 6 to the cassette side input gear 8 via the third gear 7, and drives the rack gear 12a to reciprocate the rack plate 12J.

  As shown in FIG. 6 with reference to FIG. 3, in the sheet feeding apparatus 1J of Reference Example 1, the rack gear 12a is formed on the rack plate 12J to the outside of the position where the sheet bundle (PB: FIG. 2) is lowered most. ing. The cassette side input gear 8 is always meshed with the rack gear 12a from the lower limit position to the upper limit position of the intermediate plate 2, and the rack plate 12J has more rack teeth than the minimum number of teeth necessary for raising and lowering the intermediate plate 2. Is formed.

  As shown in FIG. 7 with reference to FIG. 3, when the uppermost surface of the sheet bundle (PB: FIG. 2) comes into contact with the paper feed roller (11: FIG. 2), the paper feed pressure is reached until a predetermined contact pressure is reached. The lifter motor 4 is stopped with the spring 10 extended. Therefore, regarding the raised position of the intermediate plate 2, even if the stop position of the lifter motor 4 is slightly moved back and forth, the load on the rack gear 12 a is leveled by the expansion and contraction of the paper feed pressure spring 10, and the main body side drive train 3 up to the lifter motor 4. The load on the machine will not be excessive.

  However, in the image forming apparatus 100J, when the lifter motor 4 is rotated in the reverse direction to lower the intermediate plate 2, if the stoppage of the lifter motor 4 is delayed, a large load acts on the rack gear 12a.

  This is because the lifter motor 4 transmits the large torque amplified by the worm gear 4a to the cassette side input gear 8 in a state where the rack plate 12J hits the limit position of the reciprocating movement. This is because a large torque is transmitted from the cassette-side input gear 8 to the rack gear 12a in a state where the rack plate 12J is pushed back to the shortest sheet feeding pressure spring 10.

  In addition, when a heavy sheet bundle is stacked on the intermediate plate 2, the lowering speed of the intermediate plate 2 is increased, the possibility that the stop timing of the lifter motor 4 is delayed increases, and the impact at the time of stop increases. Even if the lifter motor 4 is stopped in time, when the intermediate plate 2 is stopped against a large inertia force, a large load is applied to the rack gear 12a of the rack plate 12J.

  A large load is applied not only to the rack gear 12a but also to the cassette side input gear 8 and the main body side drive train 3. When these engagements are lost in a state where a large load is applied, a large noise and vibration are generated, and the wear of the tooth surface increases.

<Example 1>
FIG. 8 is an explanatory view of the configuration of the sheet feeding apparatus of the first embodiment, FIG. 9 is an explanatory view of the lowered state of the middle plate in the first embodiment, and FIG. 10 is a perspective view of the middle plate raising / lowering drive mechanism as viewed from below. .

  As shown in FIG. 8 with reference to FIG. 3, in the first embodiment, the rack teeth of the rack gear 12a are set to the minimum number of teeth (rack gear 12a required for moving the rack plate 12A by a predetermined amount by the cassette side input gear 8). The number of teeth for the amount of movement.

  In other words, the driving force transmission performance of the rack teeth (12a) in the rack member (12A) is such that the pinion member (8) is idled at the position of movement of the rack member (12A) with the sheet stacking member (2) lowered. A reduced idling part is provided. In order to reduce the driving force transmission performance, the movement position of the rack member (12A) in which the sheet stacking member (2) is lowered is set outside the region where the rack teeth (12a) are formed in the rack member (12A). Has been. Reference numerals in parentheses are for convenience in understanding the correspondence with the present invention, and the present invention is not limited to the configuration of the first embodiment.

  The sheet cassette 1 </ b> A has a cassette-side input gear 8 that engages with the third gear 7 of the main body-side drive train 3 of the apparatus main body 101. When the cassette side input gear 8 rotates, the rack gear 12 a is driven to move the rack plate 12 A in the horizontal direction, and the arm portion 12 b of the rack plate 12 A rotates the intermediate plate cam 11 via the paper feed pressure spring 10. Since the intermediate plate cam 11 is fixed to one end of the pressing lever 21, the sheet feeding pressure of the sheet feeding pressure spring 10 acts on the sheet bundle (PB: FIG. 2) as the rack plate 12A moves.

  FIG. 9 shows a state when the sheet cassette 1A is mounted on the apparatus main body (101: FIG. 2) and the lifter motor 4 is rotated in the reverse direction.

  As shown in FIG. 9, when the cassette side input gear 8 continues to reverse, the cassette side input gear 8 hits the portion 13 (idling portion) of the rack gear 12a where there is no gear, so the rack gear 12a and the cassette side input gear 8 Is cut off. Therefore, the rack plate 12A is not moved to the left side in the drawing more than necessary for lowering.

  As shown in FIG. 10 with reference to FIG. 3, the cassette side input gear 8 idles outside the rack gear 12a (idle portion) even if it rotates more than necessary when the intermediate plate 2 is lowered, so that the main body side drive No load is applied to the row 3 or the rack gear 12a.

  Therefore, it is possible to prevent overloading of the main body side drive train 3 and the rack gear 12a when the stoppage of the lifter motor 4 is delayed with an inexpensive response using only the rack plate 12A. There is no noise or vibration due to tooth skipping under load.

  Since the stop positioning of the lifter motor 4 is virtually unnecessary, the control circuit including the position sensor is simplified, and the lifter motor 4 itself can be inexpensive. Since the rack gear 12a and the cassette side input gear 8 are disengaged at the lowered position and the main body side drive train 3 is not locked, slippage between the output shaft of the lifter motor 4 and the worm gear 4a does not occur.

  The structure for reducing the driving force transmission performance of the rack gear 12a is not limited to the setting of the rack tooth formation region. As will be described later in Example 3, the rack teeth may be partially retractable, or the rack teeth may be partially formed of a flexible material.

  Further, the rack teeth may be formed in a tooth shape that partially lowers the height of the rack teeth or weakens the meshing.

<Example 2>
FIG. 11 is an explanatory view of the configuration of the sheet feeding apparatus of the second embodiment, FIG. 12 is an enlarged view of the urging structure, FIG. 13 is an explanatory view of the lowered state of the intermediate plate in the second embodiment, and FIG. It is the perspective view which looked at the mechanism from the lower part.

  As shown in FIG. 11 with reference to FIG. 3, also in the second embodiment, the rack plate 12B is rotated so that the cassette side input gear 8 is idled at the moving position (idle part) of the rack plate 12B where the intermediate plate 2 is lowered. The range in which the rack gear 12a is formed is set. As in the first embodiment, the number of teeth of the rack gear 12a is limited to the minimum number of teeth required when the cassette side input gear 8 is rotated and the intermediate plate 2 is moved up and down by engaging with the main body side drive train 3. Have.

  However, in Example 2, the limit structure (14) was formed in the sheet cassette 1, and the biasing structure (15) was formed in the rack plate 12B. The limit structure (14) limits the movement of the rack member (12B) at the reciprocating position where the pinion member (8) idles. The biasing structure (15) biases the rack member (12B) from the position where the movement is stopped by the limit structure (14) to the position where the pinion member (8) meshes with the adjacent first rack tooth (12a). And push back. Reference numerals in parentheses are for convenience in understanding the correspondence with the present invention, and the present invention is not limited to the configuration of the second embodiment.

  As shown in FIG. 12, the stopper 14 is formed by cutting and raising a part of the side wall of the sheet cassette 1.

  The arm portion 12b of the rack plate 12B is resin-molded, and the spring portion 15 is integrally molded at a position facing the stopper 14 of the arm portion 12b. The spring portion 15 is integral with the rack plate 12B and is provided with a spring property on a part of the arm portion 12b, and functions to urge the rack plate 12B in the direction of the cassette side input gear 8.

  The stroke of the spring portion 15 is designed so that the rack gear 12a idles the cassette side input gear 8 at the compression position and the rack gear 12a starts to mesh with the cassette side input gear 8 at the extended position.

  As shown in FIG. 13 with reference to FIG. 3, the apparatus main body 101 has a lifter motor 4 and a main body side drive train 3 for raising and lowering the middle plate 2 of the sheet cassette 1B on the back side.

  The sheet cassette 1 </ b> B has a cassette-side input gear 8 that engages with the third gear 7 of the main body-side drive train 3 of the apparatus main body 101. When the cassette-side input gear 8 rotates, the rack gear 12a is driven to move the rack plate 12B in the horizontal direction, and the arm portion 12b of the rack plate 12B rotates the intermediate plate cam 11 via the paper feed pressure spring 10. Since the intermediate plate cam 11 is fixed to one end of the pressing lever 21, the sheet feeding pressure of the sheet feeding pressure spring 10 acts on the sheet bundle (PB: FIG. 2) as the rack plate 12B moves.

  As shown in FIG. 14 with reference to FIG. 3, when the lifter motor 4 reverses and the intermediate plate 2 reaches the lowered position, the meshing between the rack gear 12a and the cassette side input gear 8 is released, so the rack plate 12B Does not move to the left in the figure more than necessary.

  Further, when the lifter motor 4 stops, the rack plate 12B moves to a position where the meshing with the cassette side input gear 8 is restored by the restoring force of the spring portion 15. Thereby, when the cassette-side input gear 8 starts to rotate forward, the rack gear 12a can be reliably driven to start raising and lowering the intermediate plate 2 without causing noise or delay.

  Accordingly, it is possible to prevent overloading of the main body side drive train 3 and the rack gear 12a when the stoppage of the lifter motor 4 is delayed with an inexpensive support of only the rack plate 12B. There is no noise or vibration due to tooth skipping under load.

  Since the stop positioning of the lifter motor 4 is virtually unnecessary, the control circuit including the position sensor is simplified, and the lifter motor 4 itself can be inexpensive. Since the rack gear 12a and the cassette side input gear 8 are disengaged at the lowered position and the main body side drive train 3 is not locked, slippage between the output shaft of the lifter motor 4 and the worm gear 4a does not occur.

<Example 3>
FIG. 15 is an explanatory diagram of the configuration of the sheet feeding apparatus of the third embodiment, FIG. 16 is an explanatory diagram of the configuration of the rack plate in the third embodiment, and FIG. 17 is an explanatory diagram of the lowered state of the middle plate in the third embodiment.

  As shown in FIG. 15 with reference to FIG. 3, also in the third embodiment, the rack plate 12C is rotated so that the cassette side input gear 8 is idled at the moving position (idle part) of the rack plate 12C where the intermediate plate 2 is lowered. The range in which the rack gear 12a is formed is set. As in the first embodiment, the number of teeth of the rack gear 12a is limited to the minimum number of teeth required when the cassette side input gear 8 is rotated and the intermediate plate 2 is moved up and down by engaging with the main body side drive train 3. Have.

  However, in Example 3, the retraction structure (17) is provided on the rack tooth (12a) that first meshes from the reciprocating position where the pinion member (8) of the rack member (12C) idles. The retreat structure (17) retreats the rack teeth (12a) pressed by the pinion member (8) to release the engagement with the pinion member (8). Reference numerals in parentheses are for convenience in understanding the correspondence with the present invention, and the present invention is not limited to the configuration of the third embodiment.

  As shown in FIG. 16, a part of the guide groove 12m of the resin-molded rack plate 12C is extended to the rack gear 12a side to form the withdrawal structure 17. In the retracting structure 17, the rack gear 12 a is retracted inward by the resin elasticity of the rack plate 12 </ b> C, and the meshing with the cassette side input gear 8 starts flexibly.

  The retraction structure 17 is the first rack tooth with which the rack gear 12a meshes with the cassette-side input gear 8 at the lowered position of the intermediate plate (2: FIG. 3), and it is made elastic by reducing the width of the material of this portion. ing.

  As shown in FIG. 17 with reference to FIG. 3, when the lifter motor 4 reverses and the intermediate plate 2 reaches the lowered position, the rack gear 12a is retracted by the retracting structure 17 and the meshing with the cassette side input gear 8 is engaged. Idle. Thereafter, when the lifter motor 4 stops, the meshing between the rack gear 12a and the cassette-side input gear 8 is restored by the restoring force of the retracting structure 17. Thereby, when the cassette-side input gear 8 starts to rotate forward, the rack gear 12a can be reliably driven to start raising and lowering the intermediate plate 2 without causing noise or delay.

  According to the third embodiment, when the rack gear 12a starts to mesh with the cassette input gear 8, the first tooth of the rack teeth has elasticity, so that meshing smoothly and reliably. For this reason, the rack gear 12a engages with the cassette-side input gear 8 reliably and quietly with a greater shock absorption than the first embodiment, so that noise and vibration are reduced, and driving reliability is improved.

1 is a perspective view of the appearance of an image forming apparatus. 1 is an explanatory diagram of a configuration of an image forming apparatus. It is a top view of a sheet cassette. It is the perspective view which looked at the raising / lowering drive mechanism of the middle board from upper direction. It is explanatory drawing of a structure of the sheet supply apparatus of the reference example 1. FIG. FIG. 6 is an explanatory diagram of a state where a sheet bundle in Reference Example 1 is lowered. It is explanatory drawing of the state which raised the sheet | seat bundle in the reference example 1. FIG. FIG. 3 is an explanatory diagram of a configuration of a sheet feeding device according to Embodiment 1. It is explanatory drawing of the falling state of the intermediate board in Example 1. FIG. It is the perspective view which looked at the raising / lowering drive mechanism of the intermediate | middle board from the downward direction. FIG. 10 is an explanatory diagram of a configuration of a sheet feeding apparatus according to a second embodiment. It is an enlarged view of a biasing structure. It is explanatory drawing of the descent | fall state of the intermediate board in Example 2. FIG. It is the perspective view which looked at the raising / lowering drive mechanism of the intermediate | middle board from the downward direction. FIG. 10 is an explanatory diagram of a configuration of a sheet feeding device according to a third embodiment. FIG. 6 is an explanatory diagram of a configuration of a rack plate in Embodiment 3. It is explanatory drawing of the downward state of the intermediate board in Example 3. FIG.

Explanation of symbols

1A, 1B, 1C Sheet cassette 2 Middle plate 3 Main body side drive train 4 Lifter motor 7 Removable drive mechanism (third gear)
8 Pinion member (cassette side input gear)
10 Spring means (feed pressure spring)
11 Support lever (middle plate cam)
12a Rack teeth (rack gear)
12A, 12B, 12C Rack member (rack plate)
13 idling part (part without gear cutting)
14 Limit structure (stopper)
15 Biasing structure (spring part)
17 Retreat structure 100 Sheet supply device (image forming device)
101 apparatus main body 110 image forming means (system cartridge)
111 Sheet supply member (paper feed roller)
120 Control means (control unit)
P sheet PB sheet bundle

Claims (6)

A sheet cassette that has a sheet stacking member that can be moved up and down on which a bundle of sheets is stacked and that can be pulled out from the apparatus body;
A sheet supply member that abuts on the uppermost surface of the sheet bundle stacked on the sheet stacking member and feeds the sheet from the sheet cassette;
Rack members formed with rack teeth and reciprocating in a direction along the side wall;
A pinion member disposed so as to be able to mesh with the rack teeth and rotating to reciprocate the rack member;
In a sheet supply apparatus including a support lever portion that is rotatably arranged and pushes up the sheet stacking member according to the movement of the rack member.
The rack member is provided with an idling portion for reducing the driving force transmission performance of the rack teeth so that the pinion member is idly rotated at the movement position of the rack member where the sheet stacking member is lowered. A sheet supply device. A limit structure that limits the movement of the rack member at a reciprocating position where the pinion member idles;
A biasing structure that biases and pushes back the rack member from a position where the movement is stopped by the limit structure to a position where the pinion member meshes with an adjacent first rack tooth. The sheet supply apparatus according to 1.   The rack teeth that first mesh with each other from the reciprocating position where the pinion member idles are provided with a withdrawal structure that causes the rack teeth pressed by the pinion member to retract and release the engagement with the pinion member. The sheet supply apparatus according to claim 1 or 2. In the sheet cassette, the rack member and the pinion member are arranged on a side wall portion opposite to a direction in which the sheet cassette is pulled out from the apparatus main body,
The apparatus main body has a detachable drive mechanism that connects the driving force on the apparatus main body side with respect to the pinion member in conjunction with the operation of pushing the sheet cassette into the apparatus main body, facing the opposite side wall portion. The sheet feeding device according to claim 1, wherein the sheet feeding device is arranged. Control means for stopping the supply of driving force through the attachment / detachment drive mechanism at the elevation position of the sheet stacking member where the sheet bundle is brought into contact with the sheet supply member;
Spring means disposed between the rack member and a pivot end of the support lever portion that is pivotally disposed with respect to the sheet cassette and supports the sheet stacking member. The sheet feeding apparatus according to claim 4. A sheet feeding device according to any one of claims 1 to 5,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet fed from a sheet bundle.

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