JP2010168199A - Paper feeding device and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeding device and an image forming device using the same for stably feeding a paper sheet without being influenced by the shape or the position of a paper sheet penetration guide, as for the paper feeding device which uses the paper sheet penetration guide before the nip entry of a feeding roller and a separation roller. <P>SOLUTION: The paper feeding device and the image forming device include a crescent paper feed roller 16, a pair of auxiliary drive rollers 19 arranged on both sides of the paper feeding roller, a one-way clutch 191 arranged between a drive shaft 161 of the paper feeding roller and each of the auxiliary driver rollers 19, and the separation roller 17 coming into pressure contact with the paper feeding roller 16 or the auxiliary drive rollers 19. The one-way clutch 191 connects the auxiliary drive rollers 19 to the drive shaft 161 to integrally rotate the auxiliary drive rollers 19 in the rotational direction of the drive shaft by a paper feeding operation, and disconnects the auxiliary drive rollers 19 from the drive shaft 161 to rotate in a driven manner the auxiliary drive rollers 19 in accordance with the paper sheet conveyance in a paper sheet conveyance direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a paper feeding device using a half-moon paper feeding roll, an auxiliary roll, a separation roll with a built-in torque limiter, and a paper intrusion guide before entering the nip between the paper feeding roll and the separation roll. The present invention relates to a paper feeding device capable of stably supplying paper without being affected and an image forming apparatus using the paper feeding device.

  FIG. 5 is a diagram illustrating a sheet feeding device using a conventional half-moon-shaped sheet feeding roll, FIG. 6 is a diagram illustrating a sheet feeding operation of the sheet feeding device using a half-moon-shaped sheet feeding roll, and FIG. 6 is a diagram for explaining a problem of adjustment of a gap between a sheet-shaped sheet feeding roll and a sheet entry guide and sheet conveyance. In the figure, 16 is a half-moon-shaped paper feed roll, 17 is a separation roll, 18 is an auxiliary roll, 20 is a bottom plate, 21 is a paper entry guide, 161 is a drive shaft, 171 is a rotation fulcrum, and P is paper.

  2. Description of the Related Art Conventionally, a paper feeding device using a half-moon-shaped paper feeding roll 16 shown in FIG. Widely used. This paper feeder completes paper feeding and separation and paper transport to the downstream transport section by only one rotation of the paper feed roll 16, so that the drive device and control are simple, and many image formations are possible. Used in equipment.

  As the separating member, a flat friction pad has been used in many cases. However, with the diversification of transport paper, a separating roll 17 with a torque limiter having higher separating performance is often used. This is based on the difference between the friction coefficient between the separation roll and the paper and the friction coefficient between the paper and the paper. This is because the torque limiter can prevent the sheet on the separation roll from entering and prevent double feeding.

  The auxiliary roll 18 is generally smaller in diameter than the half-moon-shaped paper feed roll 16 and is generally disposed on both sides of the paper feed roll 16 around the same drive shaft 161 as the paper feed roll 16. . As shown in FIG. 6, the separation roll 17 swings around a rotation fulcrum 171 and is urged by a spring member in the direction of the half-moon-shaped paper feed roll 16 so as to be pressed against the paper feed roll 16 or the auxiliary roll 18. To do.

  As shown in FIG. 6A, the separation roll 17 is further moved by being urged by the spring member from the position of the outer peripheral portion of the paper feed roll 16 when the half-moon cutout portion of the paper feed roll 16 is in the facing position. And press-contact with the auxiliary roll 18. Accordingly, at this time, the half-moon-shaped paper feed roll 16 is not in contact with the paper P.

  Then, when the paper feeding operation is started and the drive shaft 161 is rotated and the outer peripheral portion of the paper feeding roll 16 is rotated to the position facing the separation roll 17 as shown in FIG. Is started to be pressed down by the paper feed roll 16. In this way, the separation roll 17 is oscillated by the spring member about the rotation fulcrum 171 in the direction in contact with the half-moon-shaped paper supply roll 16 and moves up and down by the paper supply operation.

  In particular, when the separation roll 17 is used as the separation member, the separation roll 17 is in a stopped state until the outer periphery of the paper feed roll 16 and the separation roll 17 are in a pressure contact state, and the curvature of the separation roll 17 is also small. There was a problem that the vertical movement of the roll 17 easily hinders the paper from entering the separation nip portion that is in pressure contact with the outer periphery of the paper feed roll 16, and non-feeding easily occurs.

  In addition, the paper feed unit separates and feeds the paper P stacked on the bottom plate 20 one by one by adjusting the gap G between the paper feed roll 16 and the paper entry guide 21 shown in FIG. If the gap G is too narrow, the leading edge of the paper P collides with the paper entry guide 21 as shown in FIG. Conversely, if the gap G is too wide, the leading edge of the paper P collides with the surface of the separation roll 17 as shown in FIG. Therefore, if the gap G between the paper entry guide 21 and the half-moon-shaped paper supply roll 16 is not properly adjusted, non-feeding is likely to occur.

  Therefore, in a paper feeder using a half-moon-shaped paper feed roll, an auxiliary roll, and a separation roll, the center of the auxiliary roll is eccentric with respect to the center of the half-moon-shaped paper feed roll, thereby reducing the vertical movement of the separation roll. There has been proposed an apparatus that makes it possible to stably feed and convey paper (for example, see Patent Document 1).

JP 2005-263374 A

  However, in the conventional apparatus, the auxiliary roll must always be at the same position with respect to the separation roll, and cannot be driven to rotate as the paper is conveyed. Therefore, since the sheet always rubs against the sheet, the load on the sheet conveyance roll (downstream) is increased, which affects the sheet conveyance accuracy and increases the size of the drive motor. In addition, since the wear of the auxiliary roll surface is large, the outer diameter is reduced, the position of the separation roll cannot be obtained stably, and the paper feeding and separation performance are affected.

  The present invention prevents the occurrence of paper non-feed due to the front end of the paper colliding with the surface of the separation roll, reduces the transport load, eliminates the adverse effect on the paper running accuracy, and provides good paper feeding and separation performance. Is to get.

  A sheet feeding device and an image forming apparatus using the sheet feeding device according to the present invention include a half-moon shaped sheet feeding roll, a pair of auxiliary driving rolls arranged on both sides of the sheet feeding roll, and driving of the sheet feeding roll. A one-way clutch disposed between a shaft and each of the auxiliary drive rolls, and a separation roll pressed against the paper feed roll or the auxiliary drive roll, and the one-way clutch is configured so that the drive shaft is driven by a paper feed operation. The auxiliary drive roll is connected to the drive shaft so that the auxiliary drive roll rotates integrally in the rotating direction, and the auxiliary drive roll is driven to rotate as the paper is conveyed in the direction in which the paper is conveyed. The drive roll is released from the connection with the drive shaft.

  And a pair of auxiliary rolls arranged on both sides of the paper feed roll and rotatably arranged on a drive shaft of the paper feed roll, and an outer peripheral surface of the auxiliary drive roll is made of resin, The outer peripheral surface of the roll is characterized by being rubber.

  According to the present invention, the auxiliary drive roll that is connected to the drive shaft via the one-way clutch is provided, and the auxiliary drive roll is rotated integrally with the drive shaft by the paper feeding operation, so that the leading edge of the sheet P collides with the surface of the separation roll. Therefore, it is possible to prevent the paper conveyance from stopping. Therefore, no paper non-feed does not occur. Further, the auxiliary drive roll after the drive shaft has stopped is in a state in which it can idle, and is driven to rotate as the paper is conveyed by the conveyance roll downstream of the paper supply roll. Therefore, the load on the transport roll is reduced, and the influence on the sheet running accuracy can be reduced.

It is a figure explaining embodiment of the paper feeder concerning this invention. It is a figure explaining other embodiment of the paper feeder concerning this invention. 1 is a diagram illustrating an embodiment of an image forming apparatus using a sheet feeding device according to the present invention. FIG. 2 is an external view of the image forming apparatus and an enlarged view of a paper feeding unit. It is a figure explaining the paper feeding apparatus using the conventional half-moon shaped paper feeding roll. FIG. 6 is a diagram illustrating a sheet feeding operation of a sheet feeding device using a half-moon shaped sheet feeding roll. FIG. 6 is a diagram for explaining a problem of adjustment of a gap between a half-moon-shaped sheet feeding roll and a sheet entry guide and sheet conveyance.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an embodiment of a paper feeding device according to the present invention, FIG. 2 is a diagram illustrating another embodiment of the paper feeding device according to the present invention, and FIG. 3 is a diagram illustrating the use of the paper feeding device according to the present invention. FIG. 4 is an external view of the image forming apparatus and an enlarged view of a paper feeding unit, 1 is a rotary developing device, 2 is a developing device, 3 is a photoreceptor, and 4 is an intermediate transfer. , 5 is an exposure device, 6 is a process unit, 7 is a primary transfer device, 8 is a secondary transfer device, 9 and 10 are paper feed devices, 11 is a registration roll, 12 is a paper transport unit, 13 is a fixing unit, 14 Is a paper discharge tray, 15 is a door, 16 is a paper feed roll, 17 is a separation roll, 18 is an auxiliary roll, 19 is an auxiliary drive roll, 20 is a bottom plate, 161 is a drive shaft, and 191 is a one-way clutch.

  In FIG. 1, the paper feed roll 16 has a half-moon notch, and the outer peripheral surface is made of a friction member such as rubber or synthetic resin having a large friction coefficient. The drive shaft 161 is rotationally driven in the direction of transporting paper by a paper feed operation, and the paper feed roll 16 is attached and fixed to the drive shaft 161. The separation roll 17 has a built-in torque limiter, and when a plurality of sheets enter, the torque limiter built in the separation roll 17 prevents the sheet on the separation roll 17 side from entering and frictionally separates and feeds one sheet. Is.

  The auxiliary rolls 18 are a pair of rolls (rollers) that are rotatably attached to the drive shaft 161 on both sides of the paper feed roll 16. The auxiliary drive rolls 19 are a pair of rolls that are attached to the drive shaft 161 via a one-way clutch 191 on both sides of the pair of auxiliary rolls 18, and at the same time for auxiliary driving the separation roll 17 at the start of the paper feeding operation. belongs to.

  The one-way clutch 191 connects the auxiliary drive roll 19 to the drive shaft 161 in the rotational direction of the drive shaft 161 that rotationally drives the paper feed roll 16 by a paper feed operation. Therefore, the auxiliary drive roll 19 rotates integrally with the paper feed roll 16 by the paper feed operation. Then, the one-way clutch 191 releases the connection between the drive shaft 161 and the auxiliary drive roll 19 in the rotational direction opposite to the direction in which the paper is conveyed, and can idle. Therefore, the auxiliary drive roll 19 is in a free rotating state as the paper is conveyed.

  The torque limiter built in the separation roll 17 is in direct contact with the paper dragged by the paper feed roll 16 when the outer peripheral surfaces formed by the friction members of the paper supply roll 16 and the separation roll 17 are in direct pressure contact with each other. In this case, the separation roll 17 is set so as to be driven to rotate by the paper feed roll 16 by the mutual frictional force. On the other hand, the torque limiter 170 is set to stop the press-contacted paper by stopping by the frictional force between the papers dragged by the paper supply roll 16.

When one sheet enters between the sheet feeding roll 16 and the separation roll 17 (separation nip), the separation roll 17 rotates following the conveyance of the sheet. However, when a plurality of sheets enter the separation nip, the entry of the sheet on the separation roll 17 side is prevented by the torque limiter built in the separation roll 17. Here, the friction coefficient between the paper feed roll 16 and the paper, the friction coefficient between the separation roll 17 and the paper, and the difference in the friction coefficient between the paper and the paper are used. As described above, the separation roll 17 having a built-in torque limiter is in pressure contact with the paper feed roll 16 in the separation nip, so that one sheet of paper can be frictionally separated and fed out. Can be prevented, and even double feeding can be prevented.

  In addition, according to the present embodiment, the drive shaft 161 and the auxiliary drive roll 19 rotate integrally by the paper feeding operation, so that the separation roll 17 is driven and rotated by the auxiliary drive roll 19 simultaneously with the rotation of the drive shaft 161. Therefore, even if the leading edge of the fed paper hits the separation roll 17, the leading edge of the paper moves along with the rotation of the separation roll 17, thereby preventing the occurrence of non-feeding.

  Furthermore, the load on the transport roll at the transport destination is reduced, and the influence on the paper running accuracy is reduced. Further, since the wear on the surface of the auxiliary roll is reduced, there is little change in the outer diameter, the positional relationship with the separation roller 17 can be maintained in a durable manner, and good paper feeding and separation performance can be obtained.

  Further, by arranging the one-way clutch 191 between the auxiliary drive roll 19 and the drive shaft 161, the auxiliary drive roll 19 is driven by one rotation by the paper feeding operation and then is a conveyance roll (at the conveyance destination of the separation nip) ( (Not shown), the sheet is idled as the sheet is conveyed. In FIG. 1, assuming that the left back direction from the right front side of the separation nip where the separation roll 17 is in pressure contact with the paper feed roll 16 is the paper conveyance direction, the conveyance roll is disposed at a conveyance destination in the left back direction of the drawing. (Not shown).

  The auxiliary roll 18 and the auxiliary drive roll 19 have an outer diameter that is about 0.5 mm smaller than the paper feed roll 16, for example, and the outer peripheral surface thereof is made of rubber or synthetic resin having a large friction coefficient, for example, like the paper feed roll 16. Consists of friction members. Here, the auxiliary drive roll 19 only needs to follow and rotate the separation roll 17 that is in pressure contact at the start of the paper feeding operation. Therefore, if resin is used for the auxiliary roll 18 using rubber, the load on the transport roll is reduced. Can be reduced.

  Further, the outer diameters of the auxiliary roll 18 and the auxiliary driving roll 19 may be the same as the outer diameter of the paper feed roll 16. When the outer diameter of the auxiliary drive roll 19 is the same as the outer diameter of the paper feed roll 16, the auxiliary drive roll 19 also has a part of the same function as the paper feed roll 16. Alternatively, the auxiliary drive roll 19 may be made shorter than before. Further, since the auxiliary drive roll 19 idles in the sheet conveyance direction and has a function as a conventional auxiliary roll 18, the auxiliary roll 18 can also be used as the auxiliary roll 18. FIG. 2 shows another embodiment in which the auxiliary roll 18 is omitted.

  As shown in FIGS. 3 and 4, the image forming apparatus using the sheet feeding device of the present embodiment includes a paper discharge tray 14 formed at the top of the housing, and a door body that can be opened and closed on the front surface of the housing. 15 In the housing, a rotary developing device 1 having a plurality of developing devices 2 mounted thereon, a photosensitive member 3 on which a latent image is formed and developed to form a toner image, and an exposure device that exposes the photosensitive member 3 to form a latent image. 5. An intermediate transfer member 4 made of an endless belt to which a toner image is transferred, and a process unit 6 for controlling the formation of a latent image by the exposure device 5 are disposed.

  Further, a primary transfer device 7 for primary transfer of the toner image on the photoreceptor 3 to the intermediate transfer member 4, a secondary transfer device 8 for secondary transfer of the toner image of the intermediate transfer member 4 to the paper, and a paper supply for housing the paper. There are provided paper devices 9 and 10, a fixing unit 13 for fixing a toner image on the paper, a control unit for controlling each drive motor and bias.

  A paper transport unit 12 that transports paper from the paper feeders 9 and 10 to the fixing unit 13 through the secondary transfer device 8 is disposed in the door body 15. Each unit is configured to be detachable from the main body, and can be removed and repaired or replaced integrally during maintenance or the like.

  The photoreceptor 3 as an image carrier has a thin cylindrical conductive substrate and a photosensitive layer formed on the surface thereof. On the outer periphery of the photosensitive member 3, a charging device (not shown) for uniformly charging the photosensitive member 3 along the rotation direction, an exposure device 5 for forming a latent image on the photosensitive member 3, a latent device A rotary developing device 1 for developing an image, an intermediate transfer member 4 to which a toner image on the photosensitive member 3 is transferred, and a primary transfer device 7 for primary transfer of the toner image to the intermediate transfer member 4 after primary transfer A cleaner (not shown) for cleaning the surface of the photosensitive member 3 is disposed.

  The latent image formed by the exposure device 5 on the photosensitive member 3 is developed by the rotary developing device 1 to form a toner image, and the formed toner image is transferred onto the intermediate transfer member 4 by the primary transfer device 7. Then, the image is further transferred onto the paper by the secondary transfer device 8.

  In full-color image formation by the image forming apparatus having the above-described configuration, when an image formation signal is input from the process unit 6 to the exposure device 5, the photoconductor 3 and the rotary developing device are controlled according to the drive motor and bias control by the control unit. 1. The intermediate transfer member 4 is driven to rotate. The outer peripheral surface of the photoreceptor 3 is uniformly charged by a charging device.

  Since the rotary developing device 1 forms a toner image of the first color, for example, yellow Y, the developing device 2 for yellow Y causes the rotation center of the rotary developing device 1 and the rotation center of the photoreceptor 3 to be changed by a developing color switching operation. Rotate and move beyond the straight line connecting Then, on the downstream side in the rotational movement direction of the rotary developing device 1, the developing roll or rollers disposed on both ends of the developing roll (hereinafter the same) contact the photoreceptor 3 and stop.

  At the same time as the developing roll of the developing device 2 is driven to rotate, the surface of the photosensitive member 3 is first subjected to selective exposure according to the image information of the first color and yellow Y by the exposure device 5, so that the surface of the photosensitive member 3 is exposed. A yellow Y latent image is formed. The yellow Y latent image is developed by the developing device 2 to form a toner image on the photoreceptor 3.

  As soon as the rear end of the yellow Y latent image is developed by the developing unit 2 and development is completed, the rotary developing device 1 immediately after that, that is, before the rear end of the toner image reaches the primary transfer device 7, The developing color switching operation for forming a color, for example, a black K toner image is started.

  By this developing color switching operation, the developing roll of the developing device 2 for black K rotates and moves further beyond the straight line connecting the rotation center of the rotary developing device 1 and the rotation center of the photosensitive member 3, and the rotary developing device 1. And abut against the photosensitive member 3 on the downstream side in the rotational movement direction.

  During this time, a primary transfer voltage having a polarity opposite to the toner charging polarity is applied to the primary transfer device 7, and the toner image formed on the photoreceptor 3 is transferred onto the intermediate transfer member 4 by the primary transfer device 7. Transcribed. The secondary transfer device 8 is separated from the intermediate transfer member 4.

When the developing color switching operation for the second color is completed and the developing roll of the developing device 2 for black K comes into contact with the photosensitive member 3 and stops, the second color, black K is applied to the surface of the photosensitive member 3 by the exposure device 5. Is selectively exposed according to the image information, and a black K latent image is formed on the photoreceptor 3. Such a series of processing is repeatedly executed corresponding to the second color, the third color, and the fourth color of the image forming signal, so that yellow Y, black K, cyan corresponding to the contents of each image forming signal. Four color toner images composed of C and magenta M are sequentially superimposed and transferred from the photosensitive member 3 onto the intermediate transfer member 4 to form a full-color image.

  Then, at the timing when the full color image reaches the secondary transfer device 8, the paper of the paper feeding devices 9, 10 is conveyed from the conveyance path to the secondary transfer device 8 through the paper feeding roll 16, the intermediate conveyance roll, and the registration roll 11. The secondary transfer device 8 is pressed against the intermediate transfer body 4 and a secondary transfer voltage is applied, and the four color full-color toner images on the intermediate transfer body 4 are transferred onto the paper by the secondary transfer device 8.

  When the sheet on which the full-color toner image has been transferred in this manner is conveyed to the fixing unit 13 by the paper conveying unit 12, the full-color toner image on the sheet is heated and pressed by the fixing unit 13 to be fixed. The paper is discharged.

DESCRIPTION OF SYMBOLS 1 ... Rotary developing device, 2 ... Developing device, 3 ... Photoconductor, 4 ... Intermediate transfer body, 5 ... Exposure device, 6 ... Process unit, 7 ... Primary transfer device, 8 ... Secondary transfer device, 9, 10 ... Paper feeding device, 11 ... registration roll, 12 ... paper transport unit, 13 ... fixing unit, 14 ... discharge tray, 15 ... door, 16 ... paper feeding roll, 17 ... separation roll, 18 ... auxiliary roll, 19 ... auxiliary drive Roll, 20 ... bottom plate, 161 ... drive shaft, 191 ... one-way clutch

Claims (5)

A half-moon-shaped paper feed roll;
A pair of auxiliary drive rolls arranged on both sides of the paper feed roll;
A one-way clutch disposed between the drive shaft of the paper feed roll and each of the auxiliary drive rolls;
A separation roll that presses against the paper feed roll or the auxiliary drive roll, and the one-way clutch rotates the auxiliary drive roll so that the auxiliary drive roll rotates integrally in a direction in which the drive shaft rotates by a paper feed operation. The paper feed is connected to the drive shaft, and the auxiliary drive roll is released from the connection with the drive shaft so that the auxiliary drive roll is driven to rotate as the paper is conveyed in a direction in which the paper is conveyed. apparatus. The paper feeding device according to claim 1, further comprising a pair of auxiliary rolls arranged on both sides of the paper feeding roll and rotatably arranged on a drive shaft of the paper feeding roll. The paper feeding device according to claim 1, wherein an outer peripheral surface of the auxiliary driving roll is made of resin. The sheet feeding device according to claim 1, wherein an outer peripheral surface of the auxiliary roll is made of rubber. An image forming apparatus using the sheet feeding device according to claim 1.

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