JP2008019027A - Paper feeding device and image forming device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a paper feeding device capable of reducing the size by eliminating a press-down cam and an image forming device equipped with the paper feeding device. <P>SOLUTION: A motor gear 28 is rotated in the D direction. Following this rotation, a rotating shaft 26 is rotated in the B direction. Due to the rotation, torque limiters 38 are rotated and pins 38B of arms 38A are lifted. Thus, since a tip part of a placement table 42 is lifted, sheet materials P are sent out to an image forming part one by one by a paper feeding roll 22. After the sheet materials P are sent out, since the placement table 42 is lowered by its own weight, double feeding of the sheet materials P is prevented and deformation of the sheet materials P due to abutment on the paper feeding roll 22 is prevented. Moreover, compared to conventional cases where the placement table 42 is pressed downwardly by a large cam, the large cam is not required and thus, the size of the paper feeding device 20 can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a paper feeding device used in an image forming apparatus such as a copying machine and a printer, and an image forming apparatus including the paper feeding device.

The image forming apparatus includes a sheet feeding device that feeds a sheet material placed on a placing plate to an image forming unit using a sheet feeding roll. (Patent Document 1)
According to this, the uppermost sheet material of the plurality of sheet materials placed on the placement plate is sent out to the image forming unit by the paper feed roll provided in the apparatus main body. At this time, in order to feed the sheet material by the paper feed roll while maintaining the conveyance performance regardless of the remaining number of sheet materials placed on the placement plate, the placement plate is directed upward toward the paper feed roll by a compression spring or the like. Further, the mounting plate must be pushed down by a pressing cam that is energized and rotates simultaneously with the paper feed roll.
Japanese Patent Laid-Open No. 11-343037

  However, in order to push down the mounting plate with the push-down cam, a certain size of the cam is required, which hinders downsizing of the paper feeding device.

  An object of the present invention is to reduce the size of the paper feeding device by eliminating the pressing cam in consideration of the above fact.

  A sheet feeding device according to a first aspect of the present invention includes a placing plate on which a sheet material is placed, a sheet feeding roll that feeds the uppermost sheet material placed on the placing plate, and the placing plate described above. And lifting and lowering means for lowering the mounting plate by its own weight while bringing the sheet material placed on the mounting plate into pressure contact with the paper feed roll.

  According to the above configuration, when the sheet material is sent to the image forming apparatus or the like, the elevating means lifts the placing plate and presses the sheet material placed on the placing plate against the sheet feeding roll. Then, the paper feed roll rotates to send the uppermost sheet material to the image forming unit.

  In addition, after the sheet material is sent out, the elevating means lowers the placing plate by its own weight to prevent the sheet material from being double fed and to prevent the sheet material from being deformed by hitting the sheet feeding roll.

  Compared to the case where the mounting plate is pressed downward with a large cam as in the prior art, a large cam is not required, and the paper feeding device can be downsized. Further, since the loading plate is lowered by its own weight, a mechanism for pushing it down is unnecessary, and the cost can be reduced.

  The sheet feeding device according to a second aspect of the present invention is the paper feeding device according to the first aspect, wherein the lifting and lowering means rotates to raise and lower the mounting plate, and the rotary lifting and lowering means previously described. The driving force transmitting means for transmitting the rotational force for raising the plate, and the switching means for releasing the transmission of the driving force by the driving force transmitting means and lowering the mounting plate by its own weight.

  According to the above configuration, the driving force transmitting means transmits the rotational force to the rotating lift means, and the rotating lift means rotates to raise the mounting plate. In addition, the switching unit cancels transmission of the driving force to the driving force transmission unit, and thereby lowers the mounting plate by its own weight.

  In this way, since the mounting plate is lifted and lowered using the rotational force, a large space is not required, and the paper feeding device can be downsized.

  According to a third aspect of the present invention, there is provided the paper feeding device according to the second aspect, wherein the driving force transmitting means transmits a rotational force of a motor that rotationally drives the paper feeding roll to the rotational rolling / lifting means. And

  According to the above configuration, the driving force rotating means transmits the rotational force of the motor that rotationally drives the paper feed roll to the rotating lift means. That is, a motor for rotating the paper feed roll and a motor for rotating the rotation raising / lowering means can be shared. Thereby, the sheet material feeding operation of the paper feed roll and the lifting / lowering operation of the mounting plate can be linked by a simple mechanism. In addition, common parts and cost reduction can be achieved.

  According to a fourth aspect of the present invention, in the paper feeding device according to the third aspect, the one-way clutch for transmitting the rotational force transmitted from the drive transmission means in the direction of feeding out the sheet material is provided on the paper feeding roll. The sheet feeding roll feeds the sheet material regardless of the direction of the rotational force transmitted from the drive transmission means.

  According to the above configuration, even if the rotational force transmitted from the driving force transmitting means to the sheet feeding roll is opposite to the sheet material feeding direction, the one-way clutch provided on the sheet feeding roll removes the sheet feeding roll from the sheet material. Enable rotation in the direction of delivery. For this reason, even if the sheet feeding roll holds the sheet material when the switching means is operated to lower the mounting plate, the sheet material is pulled by the conveyance roll downstream in the conveyance direction, and the sheet feeding roll is driven. It rotates in the direction of feeding the sheet material. For this reason, sheet material conveyance troubles such as paper jams do not occur.

  The sheet feeding device according to a fifth aspect of the present invention is the paper feeding device according to any one of the second to fourth aspects, wherein the rotation raising / lowering means applies torque to the torque limiter for limiting torque transmission and the torque limiter. An arm, a tension spring that connects the end of the arm and the mounting plate, and a driving force transmitting means is attached to a driving gear attached to a rotation shaft of a paper feed roll; It is comprised by the raising / lowering gear which meshes with a drive gear.

  According to the above configuration, the driving gear transmits the rotational force to the lifting gear that meshes with the driving gear, and the lifting gear rotates the torque limiter. As the torque limiter rotates, the end of the arm rises. As the end of the arm rises, the mounting plate connected to the end of the arm via a tension spring also rises. When the switching unit cancels the transmission of the rotational force to the drive gear, the rotational force transmitted to the elevating gear is also released, thereby releasing the rotational force transmitted to the torque limiter. When the rotational force transmitted to the torque limiter is released, the arm loses the force to lift the mounting plate, and the mounting plate is lowered by its own weight together with the arm.

  As described above, since the placing plate is raised with a predetermined torque limited by the torque limiter, the sheet material placed on the placing plate can be pressed against the sheet feeding roll with a predetermined force. Further, when the number of mounted sheets decreases as the paper is fed, the inclination of the arm changes, and the force in the direction of lifting the mounting plate decreases even if the torque value is constant. Therefore, even if the number of stacked sheets decreases and the weight decreases, the force for pressing the uppermost sheet against the sheet feeding roll does not become excessive.

  An image forming apparatus according to a sixth aspect of the present invention includes the paper feeding device according to any one of the first to fifth aspects.

  According to the above configuration, since the image forming apparatus includes the paper feeding device according to any one of claims 1 to 4, the paper feeding device of the image forming apparatus can be downsized.

  According to the present invention, it is possible to reduce the size of the paper feeding device by eliminating the pressing cam.

  A first embodiment of an image forming apparatus provided with a sheet feeding device 20 according to the present invention will be described with reference to FIGS.

  As shown in FIG. 6, the image forming apparatus 100 includes a photosensitive member 52 on which an electrostatic latent image is formed by irradiating a laser beam after being uniformly charged, and a surface of the photosensitive member 52. A charging device 54 for uniformly charging, an exposure device 56 for forming an electrostatic latent image by irradiating the photosensitive member 52 with laser light based on image data, and selectively transferring toner to the electrostatic latent image. A developing device 58 that visualizes the toner image, a transfer roll 62 that transfers the toner image on the surface of the photosensitive member 52 to a sheet material P as a recording medium supplied along the conveyance path 60, and a toner image on the sheet material P Are fixed to the sheet material P by heating and pressurizing, and a cleaning device 66 for cleaning the toner remaining on the photosensitive member 52 after the toner image is transferred.

  The image forming apparatus 100 is covered with a main body side cover 100B and a top plate 100A.

  Here, the photoconductor 52, the charging device 54, the developing device 58, and the cleaning device 66 serve as a single developing unit 67 by opening the top plate 100 </ b> A of the image forming apparatus 100, so that the main body frame (see FIG. (Not shown) can be easily attached and detached.

  The top plate 100A can be opened by rotating it in the direction of arrow A in FIG. 6 with a shaft 100C provided at the upper end corner of the body side cover 100B as a fulcrum.

  Further, in the lower part of the image forming apparatus 100, a sheet material P is stored, a sheet feeding unit 10 that feeds the sheet material P one by one, and a toner image is transferred to the sheet material P fed from the sheet feeding unit 10. A conveyance roll 68 for conveyance to the image forming unit 70 is provided.

  The paper feed unit 10 is provided inside the image forming apparatus 100 and is a paper feed cassette 80 on which a plurality of sheet materials P are placed. The paper feed unit 10 can manually feed the sheet material P to the image forming apparatus 100. Device 20. The sheet material P placed in the paper feed cassette 80 is sequentially taken out by the pickup roll 82 and further conveyed one by one by the paper feed roll 84 and the retard roll 86 that are rotationally driven. Details of the paper feeding device 20 will be described later.

  The photoreceptor 52 has a photoreceptor layer on the back surface, and the potential of the exposed portion is attenuated by exposure after being uniformly charged.

  Further, the charging device 54 is a roll-shaped member that comes into contact with the photoconductor 52, and when a voltage is applied between them, a discharge is generated in a minute gap near the contact portion, and the surface of the photoconductor 52. Is charged almost in the same way. As the charging device 54, in addition to the above, a device that applies a high voltage to the electrode wire and charges the photosensitive member 52 by corona discharge can be used.

  The exposure device 56 scans the flashing laser light on the peripheral surface of the photoconductor 52 and forms an electrostatic latent image based on the image data on the peripheral surface of the photoconductor 52. As the writing device, a light emitting element such as an LED may be arranged and blinked based on the image data.

  Further, the developing device 58 includes a cylindrical developing roll 58A disposed so as to face the photosensitive member 52 in the vicinity thereof, and a developing bias voltage is applied between the developing roll 58A and the photosensitive member 52. . As a result, a developing bias electric field is formed between the developing roller 58A and the photosensitive member 52, and the charged toner is transferred to the exposed portion on the photosensitive member 52 to form a toner image.

  The transfer roll 62 is a roll-shaped member provided so as to face the photoconductor 52, and forms a transfer electric field between the transfer roll 62 and the sheet material P passing through the image forming unit 70. The toner image is transferred to the top.

  In the image forming apparatus 100 configured as described above, an image is formed as follows.

  First, the charging device 54 to which a voltage is applied uniformly charges the surface of the photoconductor 52 with a predetermined potential.

  Subsequently, the exposure device 56 forms an electrostatic latent image on the charged photoreceptor 52 based on image data read by a scanner (not shown).

  That is, an electrostatic latent image corresponding to the image data is formed on the photoconductor 52 by turning on and off the exposure device 56 based on video data supplied from a control device (not shown). Further, the electrostatic latent image is visualized as a toner image by toner supplied from a developing roll 58A provided in the developing device 58.

  Therefore, the sheet material P taken out from the paper feed cassette 80 by the pickup roll 82 is transferred to the transport roll 68 one by one by the paper feed roll 84 and the retard roll 86 and sent to the transport path 60 to be transferred to the photoconductor 52 and the transfer roll. The toner image is transferred to the sheet material P through the image forming unit 70 between the rolls 62. The transferred toner image is fixed to the sheet material P by passing between a heating roll 64H and a pressure roll 64N provided in the fixing device 64, and discharged to the upper surface of the top plate 100A by the discharge roll 72. .

  Next, the sheet feeder 20 will be described with reference to FIGS.

  As shown in FIGS. 2 and 4, in the sheet feeding device 20 that can manually supply the sheet material P to the image forming apparatus 100, an image forming unit 70 in which an image is formed on the sheet material P supplied manually. A paper feed roll 22 is provided for feeding to (see FIG. 6). The paper feed roll 22 is provided with a one-way clutch 24. The one-way clutch 24 is provided with the paper feed roll 22 even if the rotational force transmitted to the paper feed roll 22 is opposite to the feeding direction of the sheet material P. The sheet material P can be rotated in the conveying direction (direction B shown in FIG. 2). That is, even when the rotary shaft 26 rotates in the C direction, the paper feed roll 22 can rotate in the B direction.

  Further, the retard roll 12 is provided with the sheet material P sandwiched between the paper feed roll 22. The retard roll 12 is pivotally supported by support members 14 provided at both ends, and is further biased toward the paper feed roll 22 by a biasing force of a coil spring (not shown) provided inside the support member 14. Has been.

  The retard roll 12 has a built-in torque limiter and is given a predetermined (relatively large) torque in advance. The retard roll 12 has a predetermined nip pressure by a coil spring provided in the support member 14. Is maintained. For this reason, when the rotational force of the sheet feeding roll 22 is received through one sheet material, it rotates without moving relative to the sheet material P. However, when two to three sheet materials P are double fed. Since the frictional resistance between the two or three sheet materials P is small, only the uppermost sheet material P is conveyed to the image forming unit 70 by the paper feed roll 22, and the lower layer sheet material P is formed by the retard roll 12. The feed is blocked by the rotational resistance.

  At one end of the rotating shaft 26, a motor gear 28 that transmits a rotational force from the motor 50 and a gear unit 30 that is driven to rotate are provided. Furthermore, the gear unit 30 includes a driven gear 30A that meshes with the teeth of the motor gear 28, and an electromagnetic clutch 30B that releases the connection between the driven gear 30A and the rotating shaft 26.

  Further, drive gears 32 that are driven together with the rotary shaft 26 are provided at both ends of the rotary shaft 26. Further, an elevating gear 34 that rotates following the driving gear 32 is provided below the driving gear 32. When a predetermined torque or more is applied to the rotating shaft 36 of the elevating gear 34 from the rotating shaft 36, the torque is reduced. A cylindrical torque limiter 38 for limiting transmission is provided.

  The torque limiter 38 is integrally provided with an arm 38 </ b> A that extends obliquely upward along the radially outer side of the rotary shaft 36. Further, a pin 38B is provided at the tip of the arm 38A, and the upper end of a coil spring 40 extending vertically is fixed to the pin 38B.

  The lower end of the coil spring 40 is provided at the front end portion of the side surface of the mounting plate 42 on the side where the sheet material P to be manually supplied to the image forming unit 70 (see FIG. 6) is placed (the side closer to the paper feed roll 22). The pin 42A is fixed. The placement plate 42 is provided with a regulation guide 42C that regulates the placement position of the sheet material P in the width direction.

  Further, as shown in FIG. 6, the base end portion of the mounting plate 42 is attached to a frame member (not shown) by a shaft portion 42B, and the mounting plate 42 can swing around the shaft portion 42B. It has become.

  With this configuration, when the sheet material P placed on the placing plate 42 is conveyed to the image forming unit 70, the motor gear 28 rotates in the direction D shown in FIG. The driven gear 30A rotates in the B direction shown in FIG. 2, whereby the rotation shaft 26 connected by the electromagnetic clutch 30B rotates in the B direction.

  When the rotary shaft 26 rotates in the B direction, the drive gears 32 at both ends rotate in the B direction, and the lift gear 34 disposed below the drive gear 32 following this rotates in the E direction. The rotating shaft 36 also rotates in the E direction. Further, the torque limiter 38 attached to the rotary shaft 36 rotates, and the pin 38B of the arm 38A of the torque limiter 38 rises.

  As the pin 38B rises, the upper end of the coil spring 40 attached to the pin 38B is pulled upward, and thereby the mounting plate 42 swings around the shaft portion 42B (see FIG. 6). The tip is lifted upward.

  When the leading end of the mounting plate 42 is lifted, the leading end of the sheet material P placed on the mounting plate 42 is pressed against the paper feed roll 22, and the sheet material P receives the rotational force of the rotary shaft 26. Are fed one by one to the image forming unit 70 by the sheet feeding roll 22 and the retard roll 12 that rotate in turn.

  Here, in order to raise the mounting plate 42 with a predetermined torque limited by the torque limiter 38, the sheet material P mounted on the mounting plate 42 can be pressed against the paper feed roll 22 with a predetermined force, The arm 38A stops at a predetermined position.

  Further, after the sheet material P is sent out, the transmission of the driving force to the rotating shaft 26 is released by the electromagnetic clutch 30B of the gear unit 30.

  Here, even if the driving force is released by the electromagnetic clutch 30 </ b> B while the sheet feeding roll 22 is nipping and conveying the sheet material P, the rotation transmitted to the sheet feeding roll 22 is provided because the one-way clutch 24 is provided. Even if the force is reverse to the sheet material feeding direction, the sheet feeding roll 22 can rotate in the sheet material feeding direction (B direction). Therefore, even if the paper feed roll 22 sandwiches the sheet material P, the sheet material P is pulled by the transport roll 68 (see FIG. 6) disposed downstream of the paper feed roll 22 in the transport direction. It is driven to rotate in the direction of feeding the sheet material P. For this reason, sheet material conveyance troubles such as paper jams do not occur.

  Further, the transmission of the driving force to the rotating shaft 26 is released, so that the rotating force of the rotating shaft 36 is also released, and thereby the rotating force of the torque limiter 38 is also released. When the rotational force of the torque limiter 38 is released, the arm 38A loses the force to lift the mounting plate 42, the mounting plate 42 is lowered by its own weight, and the pin 38B of the arm 38A is also lowered.

  As shown in FIGS. 1, 3, and 5, when the mounting plate 42 is lowered, a plurality of sheet materials P can be set.

  When the rotating shaft 36 rotates in the F direction, the idling torque of the one-way clutch 24 acts on the rotating shaft 36, and the tip of the mounting plate 42 does not drop rapidly. For this reason, generation | occurrence | production of abnormal noise etc. is prevented.

  Further, the arm 38A is provided with a stopper (not shown), and is configured to stop at a predetermined position when the paper feed roll 22 and the mounting plate 42 are sufficiently separated from each other.

  Therefore, after the sheet material P is sent out, the placing plate 42 is lowered by its own weight, so that the sheet material P is prevented from being double-fed and the sheet material P is prevented from being deformed by hitting the paper feed roll 22.

  Further, as compared with the conventional case where the mounting plate 42 is pressed downward with a large cam, a large cam is not required, and the paper feeding device 20 can be downsized. In particular, conventionally, when the number of sheet materials P that can be placed on the placement plate 42 is increased, the cam has to be increased in size. However, since no cam is required, the placement capacity of the sheet material P can be improved. .

  Further, since the motor 50 for rotating the paper feed roll 22 and the motor for rotating the torque limiter 38 are shared, the sheet material P feeding operation of the paper feed roll 22 and the raising / lowering operation of the mounting plate 42 can be linked. . Furthermore, a dedicated motor for raising and lowering the mounting plate 42 is not required, and the structure is inexpensive.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above-described embodiment, the pin 38B of the arm 38A and the pin 42A of the mounting plate 42 are connected through the spring 40. However, the spring 38 is not particularly used and may be attached via a wire or the like.

  In the above-described embodiment, the arm 38A and the coil spring 40 are used to change the rotational force of the rotary shaft 36 to the lifting / lowering operation. You may change it.

  Next, a second embodiment of the image forming apparatus 100 employing the paper feeding device 110 of the present invention will be described with reference to FIG.

  In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In this embodiment, as in the first embodiment, the rotating shaft 26 of the paper feed roll 22 is not provided with a gear that meshes with the motor gear.

  Specifically, a first gear 128 and a one-way clutch 130 are provided on the rotation shaft of the paper feed roll 22. The one-way clutch 130 rotates the sheet feeding roll 22 in the sheet material P conveying direction (B direction shown in FIG. 7) even if the rotational force transmitted to the sheet feeding roll 22 is opposite to the feeding direction of the sheet material P. enable. That is, even when the first gear 128 rotates in the C direction, the paper feed roll 22 can rotate in the B direction.

  Further, a first gear 128 and a drive gear 126 that is driven to rotate are provided obliquely above the first gear 128, and a motor unit 120 and a gear unit 122 that is driven to rotate are provided at one end of the rotating shaft 124 of the drive gear 126. Yes. The gear unit 122 is provided with a driven gear 122A that meshes with the teeth of the motor gear 120, and an electromagnetic clutch 122B that releases the connection between the driven gear 122A and the rotating shaft 124.

  A second gear 132 that rotates following the drive gear 126 is provided obliquely below the drive gear 126. Further, an elevating gear 34 that rotates following the second gear 132 is provided on the side of the second gear 132, and a predetermined torque or more is applied to the rotating shaft 36 of the elevating gear 34 from the rotating shaft 36. And a cylindrical torque limiter 38 for limiting the transmission of torque.

  In this embodiment, the motor gear 120 and the gear unit 122 are provided only on one side with respect to the paper feed roll 22.

  With this configuration, when the sheet material P placed on the placing plate 42 is conveyed to the image forming unit 70, the motor gear 120 is rotationally driven in the G direction shown in FIG. The driven gear 122A rotates in the H direction shown in FIG. 7, whereby the rotating shaft 124 connected by the electromagnetic clutch 122B rotates in the H direction.

  When the rotation shaft 124 rotates in the H direction, the drive gear 126 rotates in the H direction, and the first gear 128 rotates in the B direction. Accordingly, the rotation shaft 26 and the paper feed roll 22 also move in the B direction. Rotate to. Accordingly, the sheet material P is sent out to the image forming unit.

  Further, the second gear 132 is also driven and rotated by the rotation of the drive gear 126, whereby the second gear 132 and the lifting and lowering gear 34 that is driven to rotate are rotated and the rotary shaft 36 is rotated in the J direction. Further, the torque limiter 38 attached to the rotary shaft 36 rotates, and the pin 38B of the arm 38A of the torque limiter 38 rises. As the pin 38B rises, the tip of the mounting plate 42 is lifted.

  Further, after the sheet material P is sent out, the transmission of the driving force to the rotating shaft 26 is canceled by the electromagnetic clutch 122B of the gear unit 122.

  Here, even if the driving force is released by the electromagnetic clutch 122 </ b> B while the sheet feeding roll 22 is sandwiching the sheet material P, the rotational force transmitted to the sheet feeding roll 22 is provided because the one-way clutch 130 is provided. Even if the sheet feeding direction is opposite to the sheet feeding direction, the sheet feeding roll 22 can rotate in the B direction. Therefore, the sheet material P is pulled by a conveyance roll disposed downstream in the conveyance direction of the paper feed roll 22, and the paper feed roll 22 is driven to rotate in a direction in which the sheet material P is fed. For this reason, sheet material conveyance troubles such as paper jams do not occur.

  Furthermore, by releasing the transmission of the driving force to the rotating shaft 124, the rotating force of the rotating shaft 36 is also released, and thereby the rotating force transmitted to the torque limiter 38 is also released. When the rotational force transmitted to the torque limiter 38 is released, the arm 38A loses the force to lift the mounting plate 42, the mounting plate 42 is lowered by its own weight, and the pin 38B of the arm 38A is also lowered.

  In this way, the rotational force from the motor 50 to the torque limiter 38 can be transmitted and released without going through the rotating shaft 26 of the paper feed roll 22, so that even when the rotating shaft 26 fails, it can be loaded. The mounting plate 42 can be lowered.

FIG. 3 is a perspective view illustrating the sheet feeding device according to the first embodiment of the present invention and illustrating a state in which the mounting plate has moved downward. FIG. 3 is a perspective view illustrating the sheet feeding device according to the first embodiment of the present invention and illustrating a state in which the placement plate has moved upward. FIG. 4 is a side view illustrating the sheet feeding device according to the first embodiment of the present invention and illustrating a state in which the placement plate has moved downward. FIG. 3 is a side view illustrating the sheet feeding device according to the first embodiment of the present invention and illustrating a state in which the placement plate has moved upward. It is the front view which showed the paper feeder which concerns on 1st Embodiment of this invention, and showed the state which the mounting plate moved below. 1 is a schematic configuration diagram of an image forming apparatus employing a paper feeding device according to a first embodiment of the present invention. It is the perspective view which showed the paper feeder which concerns on 2nd Embodiment of this invention.

Explanation of symbols

20 Paper Feeder 22 Paper Feed Roll 24 One Way Clutch 30B Electromagnetic Clutch (Switching Unit)
32 Drive gear 34 Lifting gear 36 Rotating shaft (Rotating shaft)
38 Torque limiter 38A Arm 40 Coil spring (Tension spring)
42 Mounting plate 50 Motor 70 Image forming unit 122B Electromagnetic clutch (switching means)
126 Drive gear 130 One-way clutch

Claims (6)

A mounting plate on which the sheet material is mounted;
A paper feed roll for feeding out the uppermost sheet material placed on the placing plate,
Lifting means for lifting the mounting plate from above, pressing the sheet material placed on the mounting plate against the paper feed roll, and lowering the mounting plate by its own weight;
A sheet feeding device comprising:   The elevating means rotates to elevate and lower the placing plate, driving force transmitting means for transmitting rotational force for raising the placing plate to the rotating elevating means, and driving force transmission 2. The sheet feeding device according to claim 1, further comprising switching means for releasing transmission of the driving force by the means and lowering the placing plate by its own weight.   The sheet feeding device according to claim 2, wherein the driving force transmitting unit transmits a rotational force of a motor that rotationally drives the sheet feeding roll to the rotating lifting unit.   The paper feed roll is provided with a one-way clutch that transmits the rotational force transmitted from the drive transmission means in a direction in which the sheet material is sent out, regardless of the direction of the rotational force transmitted from the drive transmission means. The sheet feeding device according to claim 3, wherein the sheet feeding roll feeds out the sheet material.   The rotation raising / lowering means is composed of a torque limiter for limiting transmission of torque, an arm for applying torque to the torque limiter, and a tension spring for connecting an end of the arm and the mounting plate, and transmits driving force. 5. The apparatus according to claim 2, wherein the means comprises a drive gear attached to the rotation shaft of the paper feed roll and a lifting gear attached to the torque limiter and meshing with the drive gear. The paper feeder described in the section.   An image forming apparatus comprising the paper feeding device according to claim 1.

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