JP2008013297A - Paper feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeder having a constitution in which a bottom plate is elevated/lowered with respect to a paper feed roller every time one paper sheet is fed, which is capable of reducing the cost, saving the space, suppressing degradation of the separation performance by suppressing generation of an impact when the bottom plate is elevated, and suppressing any slip on a separation nip part of paper sheets. <P>SOLUTION: Every time the paper feed is started, the rotation of a single driving source for driving a paper feed roller 31 and a bottom plate 32 is reduced. The moving speed of the bottom plate 32 and the rotational speed of the paper feed roller 31 are reduced below predetermined values (normal speeds), respectively from the start of elevation to the end of elevation of the bottom plate 32. The speeds are kept reduced before a leading edge of a paper sheet P enters a nip part N, and the speeds are returned to the normal speeds. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a paper feed roller for feeding paper, a bottom plate that presses the placed paper against the paper feed roller, and a separation member that separates and conveys the fed paper. It relates to the device.

  In a paper feeding device mounted on an image forming apparatus such as a copying machine, a paper feeding device that feeds paper one by one in a predetermined direction is required to be inexpensive and capable of passing a wide variety of paper types. It has been. Among them, a low-cost friction pad separation type structure has been conventionally employed (see Patent Documents 1 to 3).

  As a general configuration of the friction pad separation system, a sheet feeding roller (roller) and a friction pad, which is a separation pad member, come into contact with each other at a nip portion at a predetermined pressure, and a sheet placed thereon is placed on a bottom plate. It is configured to be pressed against the paper feed roller. The base plate is always pressed against the paper feed roller and the bottom plate moves between the retracted position and the pressure contact position for each paper to be fed, and is located at the retracted position when not operating. There is a thing of the structure which is doing.

The latter configuration uses a paper feed mechanism that raises and lowers the bottom plate once each time a sheet is fed, so that the user does not need to press the bottom plate when replenishing the paper. Often employed in the department (see Patent Document 4).
Japanese Utility Model Publication No. 1-111641 Japanese Patent Laid-Open No. 5-278884 JP 2000-128379 A JP 2005-194082 A

  In the conventional technique, the bottom plate moves between the retracted position and the press-contact position with respect to the sheet feeding roller for each sheet to be fed, and is located at the retracted position when not operating. Unlike the regular contact configuration where the paper on the bottom plate is always in contact with the paper feed roller during feeding, the paper feed roller and paper are brought into contact with and separated from each other when the bottom plate moves up and down. Fluctuations are large, and it is easy for transport problems to occur. In particular, multiple sheet feeding (double feeding) is a concern. Further, when the bottom plate rises and comes into contact with the sheet feeding roller, there is a problem that the impact sound is felt as noise.

  The object of the present invention is to solve the problems of the prior art and to reduce the cost and space in a structure in which the bottom plate moves up and down once relative to the sheet feeding roller each time a sheet is fed. It is an object of the present invention to provide a paper feeding device that can suppress the occurrence of an impact when the bottom plate is raised, suppress a decrease in separation performance, and suppress a slip at a separation nip portion of a sheet.

  In order to achieve the above object, the invention according to claim 1 is a paper feeding roller for feeding paper, a bottom plate that presses the placed paper against the paper feeding roller, and a paper feeding roller that feeds paper more than the bottom plate. A separation member that separates and conveys the sheets one by one at a separation nip portion with the sheet feeding roller on the downstream side in the sheet direction, and the sheet and the sheet feeding each time the sheet placed on the bottom plate is fed once. In a sheet feeding device including a bottom plate elevating member that moves the bottom plate so as to contact and separate a paper roller, a single drive source for operating the sheet feeding roller and the bottom plate elevating member is provided as a period for ascending the bottom plate And a control unit for controlling the moving speed of the bottom plate and the rotational speed of the paper feed roller to be reduced. With this configuration, the sheet is fed to the paper on the bottom plate by lowering the bottom plate raising speed. Reduce the impact when the paper roller contacts, Reduces separation performance (specifically, an upward force is applied to the feed roller due to the impact when the bottom plate rises, and the separation pressure is released, making it easier for paper to bunch through the separation nip) Can be deterred. In addition, it is possible to reduce the noise during the bottom plate rising impact. Further, by lowering the rotation speed of the paper feed roller at the moment when the bottom plate rises and the paper comes into contact with the paper feed roller, it is possible to secure the clamping state at the paper separation portion and suppress paper slip. Furthermore, since the drive source is single, cost reduction and space saving can be achieved.

  According to a second aspect of the present invention, in the paper feeding device according to the first aspect, the drive source is decelerated from the start of rising of the bottom plate until the front end of the paper passes through the separating member. The contact of the sheet with the sheet feeding roller and the separation conveyance at the separation nip portion are stably performed, and the load fluctuation is reduced, so that the load on the drive source is reduced and stable drive control is possible.

  According to a third aspect of the present invention, in the paper feeding device according to the first or second aspect, the deceleration can be adjusted. With this configuration, the double feed due to the deceleration of the bottom plate ascending section or the noise suppressing effect can be achieved. It is possible to adjust the balance between the reduction in noise suppression effect caused by not decelerating at the separation nip portion according to the use such as the paper type.

  According to a fourth aspect of the present invention, in the paper feeding device according to any one of the first to third aspects, the timing of decelerating release can be switched between before the paper leading edge enters the separating member and after the paper leading out. This configuration makes it possible to adjust the balance between the noise suppression effect and the load fluctuation suppression according to the application.

  According to a fifth aspect of the present invention, in the paper feeding device according to any one of the first to fourth aspects, the time required for the paper to reach an arbitrary part in the paper feeding path from the start of feeding is constant. The speed of the deceleration cancellation section is changed in accordance with the speed change of the deceleration section.With this configuration, even if the configuration of the present invention is adopted, the time of the entire process is not changed, thereby improving the productivity. Can be maintained.

  According to a sixth aspect of the present invention, in the paper feeding device according to the first or second aspect, the height direction position of the uppermost sheet of the paper placed on the bottom plate is detected by a sensor, and the bottom plate is raised. The present invention is characterized in that deceleration is started before the sheet feeding roller and the sheet come into contact with each other. With this configuration, the number of deceleration sections can be reduced as much as possible, and the productivity can be increased accordingly.

  According to a seventh aspect of the present invention, in the paper feeding device according to the sixth aspect, the sensor is an optical detection sensor.

  According to an eighth aspect of the present invention, in the paper feeding device according to the seventh aspect, the optical detection sensor comprises a transmissive photointerrupter or a reflective photointerrupter.

  According to a ninth aspect of the present invention, in the paper feeding device according to the sixth aspect, the sensor comprises a load cell.

  A tenth aspect of the present invention is the paper feeding device according to the first or second aspect, further comprising a sensor for detecting the rising height of the bottom plate, and the height of the uppermost paper varies due to the curling of the paper. Since there is a possibility, the detection accuracy can be improved by setting the detection target of the rising height not the paper but the bottom plate having a rigid body with little height variation.

  According to the eleventh aspect of the present invention, in the paper feeding device according to the tenth aspect, the height immediately before the bottom plate ascent is completed when the sheet stacking amount is small is detected by the sensor that detects the ascent height of the bottom plate. With this configuration, the impact when the bottom plate rises is large when the paper load is small (when the paper load is large, the paper becomes an impact mitigating material), so when the paper load is small It is possible to avoid a decrease in productivity as much as possible by lowering the bottom plate raising speed only.

  The invention according to claim 12 is characterized in that, in the paper feeding device according to any one of claims 1 to 11, when the raising of the bottom plate is completed, the drive source is temporarily stopped. When an impact occurs when the bottom plate is raised, the sheet conveyance is temporarily stopped, and the conveyance can be resumed after the influence of the impact is subsided, and the conveyance quality can be stabilized.

  According to a thirteenth aspect of the present invention, in the paper feeding device according to the twelfth aspect of the present invention, the time for stopping the drive source is variable, and the stop time is adjusted according to the use such as the paper type by this configuration. It becomes possible to do.

  According to a fourteenth aspect of the present invention, in the image forming apparatus that feeds sheets one by one from the sheet feeding unit to the image forming unit and forms an image on the sheet by the image forming unit, the sheet feeding unit is charged. Item 14. The paper feeding device according to any one of Items 1 to 13 is mounted. With this configuration, stable separation and conveyance with respect to the sheet is performed, and the sheet feeding is stabilized. Therefore, highly reliable image formation is achieved. Realize.

  According to the present invention, when the bottom plate moves up and down once with respect to the sheet feeding roller each time a sheet is fed, the sheet on the bottom plate and the sheet feeding roller come into contact with each other by decreasing the bottom plate ascent speed. Therefore, it is possible to suppress a decrease in separation performance due to the impact, to suppress the occurrence of double feed, and to reduce noise during a bottom plate rising impact. Moreover, by lowering the rotation speed of the paper feed roller when the bottom plate rises and the paper comes into contact with the paper feed roller, the clamping state at the paper separation unit can be ensured, and paper slip can be suppressed. Separation feeding can always be performed in a good and stable state. Furthermore, since the drive source is single, cost reduction and space saving can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of an electrophotographic tandem type color copier for explaining an embodiment of the present invention. An image forming unit 2 is disposed at a substantially central portion of the apparatus main body 1, and a lower portion thereof. A paper feed unit 3 is provided. In this embodiment, the paper feed unit 3 is provided with four stages of paper feed cassettes 4a to 4d. These paper feed cassettes 4a to 4d are provided so as to be able to be drawn out and stored in the front-rear direction (the front and back direction in FIG. 1) with respect to the apparatus main body 1.

  A scanner 5 that reads an original image by optical-electrical conversion is arranged above the image forming unit 2, and on the downstream side (left side in FIG. 1) of the image forming unit 2 in the paper transport direction, the image-formed paper A paper discharge tray 7 for discharging P is provided. Note that a manual feed tray 8 serving as a cover for the apparatus main body 1 and for manually feeding the paper P can be opened and closed on the upstream side (right side in FIG. 1) of the image forming unit 2 in the paper conveyance direction. Is provided.

  The image forming unit 2 is provided with an image forming unit 10 for yellow (Y), magenta (M), cyan (C), and black (K) above an intermediate transfer belt 9 formed of an endless belt. Yes. The image forming unit 10 performs exposure irradiation by a charging device 12, a developing device 13, a cleaning device 14, and an exposure device 15 constituting an electrophotographic process along the outer periphery of a plurality of drum-shaped photoreceptors 11 provided for each color. Each part 15a is arranged.

  The charging device 12 performs a charging process on the surface of the photoconductor 11, and the exposure light irradiation unit 15 a of the exposure device 15 irradiates the surface of the photoconductor 11 with laser light that exposes image information. The developing device 13 develops and visualizes the electrostatic latent image formed by exposing the surface of the photoconductor 11 with toner, and the cleaning device 14 removes the toner remaining on the surface of the photoconductor 11 after transfer. to recover.

  As an image forming process, the toner image on each photoconductor 11 is transferred onto the intermediate transfer belt 9 and four color images are superimposed on the intermediate transfer belt 9 to form one color image. The color image on the intermediate transfer belt 9 is transferred by the transfer device 16 to the paper P fed from the paper feed cassettes 4a to 4d or the manual feed tray 8, fixed by the fixing device 17, and then discharged from the paper discharge roller. The paper is discharged to the paper discharge tray 7 by 18.

  Each of the paper feed cassettes 4 a to 4 d and the manual feed tray 8 and the registration roller 19 are connected by a conveyance path 20, and the paper P fed from an arbitrary paper supply location passes through the conveyance path 20 to the registration roller. Up to 19. The registration roller 19 temporarily stops the conveyance of the paper P, and sends out the paper P at a timing so that the positional relationship between the toner image on the intermediate transfer belt 9 and the leading edge of the paper P becomes a predetermined positional relationship.

  The paper feed device according to the present invention can be applied to any of the paper feed cassettes 4a to 4d and the manual feed tray 8. However, the present embodiment will be described as an application example of the manual feed tray 8 to the paper feed device 30. To do.

  FIG. 2 is a perspective view showing the paper feeding device 30 extracted with the manual tray 8 in FIG. 1 being opened, and FIG. 3 is a diagram illustrating a state in which the manual tray 8 and a member that guides the fed paper P are removed. FIG. 4 is a perspective view showing a pressure plate that is a part of the paper feeding device 30, and FIG. 5 is a perspective view showing the pressure plate from the back side.

  The paper feed device 30 for manual feed is configured as a friction pad separation type paper feed device, and in this example, a paper feed roller 31 for feeding paper P stacked on the manual feed tray 8; FIG. 3 shows a bottom plate 32 that is positioned near the front end side of the manual feed tray 8 in the paper feed direction and is movable between a pressure contact position where the stacked paper P is pressed against the paper feed roller 31 and a retreat position where the pressure contact is released. As described above, a plate-like member that is a separation member provided with a friction pad 33a that separates the sheets P fed one by one in contact with the lower surface of the sheet feeding roller 31 downstream of the sheet feeding direction from the bottom plate 32. A separation pad member 33 and the like are provided.

  In the separation pad member 33, the friction pad 33a is formed of a material having a high friction coefficient such as rubber, rubber cork, urethane foam, and thermoplastic elastomer. Further, the downstream side of the separation pad member 33 in the paper feeding direction (the side opposite to the paper entering direction) is rotatably supported by the support shaft 33b.

  In the paper feeding direction of the paper P fed from the manual feed tray 8, a conveyance guide plate 34a for guiding the lower surface side of the paper P to be fed, and side plates erected on both sides of the conveyance guide plate 34a. A resin structure 34 integrally formed with 34b is provided.

  The paper feed roller 31 and the separation pad member 33 are positioned at substantially the center in the paper width direction orthogonal to the paper feed direction of the paper P stacked on the manual feed tray 8, and the paper feed roller 31 extends in the paper width direction. The sheet feeding roller shaft 35 is fixed. Both ends of the paper feed roller shaft 35 are rotatably attached to the side plate 34b via bearings 36.

  In addition, as shown in FIG. 3, the paper feed roller 31 is formed in a shape in which a part of the outer peripheral portion of the cylinder is cut out in a plane parallel to the center line, and the outer peripheral surface is a circular portion 31 a; And a notch 31b. A disc-shaped guide roller 37 having a smaller diameter than the roller portion 31a of the paper supply roller 31 is fixed to both ends of the paper supply roller 31 (in FIG. 3, the guide roller 37 on one side is omitted).

  Cams 38 constituting a bottom plate raising / lowering member formed in a sector shape are fixed to both ends of the sheet feeding roller shaft 35. A chipped gear 39 for transmitting a driving force to the paper feed roller shaft 35 is fixed to one end side of the paper feed roller shaft 35. The chipped gear 39 is a gear that is not shown in the figure, but with a part of a circular gear cut out, and the chipped gear 39 and the output gear 56 of the motor 55 that is a single drive source mesh with each other. The paper feed roller shaft 35 and the paper feed roller 31 are rotationally driven. When the output gear 56 opposes the notch portion of the chipped gear 39, the driving force transmission from the output gear 56 to the chipped gear 39 is interrupted, and the rotation of the paper feed roller shaft 35 and the paper feed roller 31 is stopped. The

  As shown in FIG. 3, a feed roller position regulating member 40 is fixed to the other end side of the feed roller shaft 35. A first protrusion 41 is formed on the sheet feeding roller position regulating member 40, and the rotation of the sheet feeding roller shaft 35 and the sheet feeding roller 31 is regulated by engaging the flapper 44 of the solenoid 43 with the first protrusion 41. Is done. Further, a second protrusion 45 is formed on the paper feed roller position regulating member 40, and the paper feed roller shaft 35 and the paper feed roller 31 are urged to rotate in the paper feed direction of the paper P on the second protrusion 45. A tension spring 46 is provided.

  The rotation of the paper feed roller shaft 35 and the paper feed roller 31 is intermittently performed as follows.

  That is, the solenoid 43 is turned off at the timing when the chipped gear 39 and the output gear 56 are not engaged with each other, and the flapper 44 is locked to the first protrusion 41. As a result, the paper feed roller shaft 35 and the paper feed roller 31 are maintained in the rotation stopped state. Thereafter, the solenoid 43 is turned on at a certain timing, and the locking of the flapper 44 to the first protrusion 41 is released. When the locking is released, the paper feeding roller shaft 35 and the paper feeding roller 31 are rotated in the paper feeding direction by the urging force of the tension spring 46, and the chipped gear 39 is engaged with the output gear 56 by this rotation.

  When the chipped gear 39 meshes with the output gear 56, the chipped gear 39 rotates substantially once until the position where the output gear 56 stops meshing with the chipped gear 39 again, and the paper feed roller 31 also rotates approximately once. At a timing when the chipped gear 39 rotates substantially once and the chipped gear 39 and the output gear 56 do not mesh with each other, the solenoid 43 is turned off and the flapper 43 is locked to the first protrusion 41 to feed the paper feeding roller. The shaft 35 and the paper feed roller 31 are maintained in the rotation stopped state.

  A portion of the conveyance guide plate 34a corresponding to the paper feed roller 31 is opened, and a separation pad member 33 is disposed in the opening portion. As described above, the separation pad member 33 is rotatably supported with the support shaft 33b as a fulcrum, and a flat friction pad 33a is bonded to the upper surface of the separation pad member 33 with a double-sided tape. A compression spring 47 is disposed below the separation pad member 33, and the friction pad 33 a is pressed against the outer peripheral surface of the paper feed roller 31 by the pressure applied by the compression spring 47.

  The bottom plate 32 is formed of a resin, and on both sides in the direction orthogonal to the paper feeding direction of the paper P and on the portion outside the stacking range of the paper P, an arc-shaped protrusion 32a that constitutes the bottom plate lifting member facing the cam 38. A guide roller 48 that is in contact with the peripheral edge of the cam 38 is attached to the arc-shaped protrusion 32a. The guide roller 48 is formed of a resin such as polyacetal. The attachment portion of the guide roller 48 is a U-shaped groove whose entrance is slightly narrower than the guide roller shaft. When attaching the guide roller 48, the groove is pushed and expanded using the elasticity of the resin. 48 is configured so that it cannot be easily removed.

  A concave stepped portion 32b is formed at the center of the bottom plate 32 in the direction orthogonal to the paper feeding direction of the paper P and at a position facing the paper feeding roller 31, and a friction pad 49 is attached to the concave stepped portion 32b. ing.

  A guide pin 50 is attached to the structure 34 in the vicinity of the side plate 34b. Both guide pins 50 are members that serve as guides when the bottom plate 32 moves between the press-contact position and the release position. On both sides of the bottom plate 32 in the direction orthogonal to the paper feed direction of the paper P, FIG. As shown, a guide hole 51 through which the guide pin 50 is inserted is formed. These guide holes 51 are formed in portions outside the stacking range of the paper P so as not to hinder the paper P feeding operation.

  As shown in FIG. 5, a conical compression spring 52, which is a pressurizing unit that pressurizes the bottom plate 32 toward the paper feed roller 31, is attached between the bottom plate 32 and the structure 34. The compression spring 52 is wound so as to surround the outer periphery of the guide pin 50, and is arranged so that the pressing direction by the compression spring 52 is coaxial with the guide hole 51.

  In such a configuration, as described above, the feeding roller shaft 35 and the feeding roller 31 are intermittently connected by switching the solenoid 43 on and off and transmitting the driving force from the output gear 56 to the chipped gear 39. Is rotationally driven. During this intermittent rotation drive, the cam 38 rotates integrally. As the cam 38 rotates, the cam 38 abuts on the arc-shaped protrusion 32a and the guide roller 48, or the abutting state is released, and accordingly, the compression spring 52 moves toward the sheet feeding roller 31 side. The pressed bottom plate 32 moves in a direction in which it is in contact with or separated from the paper feed roller 31.

  Specifically, when the roller portion 31a of the paper feed roller 31 is opposed to the bottom plate 32, the cam 38 is in a non-contact state with respect to the arc-shaped protrusion 32a and the guide roller 48, and the bottom plate 32 is loaded paper. It has moved to the pressure contact position where P is pressed against the roller portion 31 a of the paper feed roller 31. On the other hand, when the cam 38 comes into contact with the arc-shaped protrusion 32 a and the guide roller 48, the bottom plate 32 moves to a retracted position in a direction away from the paper supply roller 31, and the pressure contact of the paper P with the paper supply roller 31 is released. .

  The direction of pressure applied by the compression spring 52 acting on the bottom plate 32 is coaxial with the guide hole 51 through which the guide pin 50 is inserted, and the cam 38 is positioned in the vicinity of the guide hole 51 with the arc-shaped protrusion 32a and the guide. It is in contact with the roller 48. For this reason, the bending stress which acts on the baseplate 32 when the baseplate 32 moves between a press-contact position and a retracted position becomes small. For this reason, even if the bottom plate 32 is made of resin, the bottom plate 32 is not easily deformed when the bottom plate 32 moves between the contact position and the retracted position by the pressure of the compression spring 52 and the control of the cam 38. As a result, the durability of the base plate 32 is increased, and the sheet feeding performance of the bottom plate 32 is prevented from being lowered due to deformation.

  By forming the bottom plate 32 with resin, the generation of static electricity due to friction with the paper P and the accumulation of the generated static electricity are small, and the grounding process for releasing the static electricity becomes unnecessary.

  FIG. 6 is a cross-sectional view showing a main part of a manual sheet feeding device that is Embodiment 1 of the sheet feeding device according to the present invention. The sheet feeding device 30 for manual sheet feeding includes a friction pad separation system. As described above, the sheet feeding device includes the manual feed tray 8, the sheet feeding roller 31, the bottom plate 32, and the plate-like separation pad member 33 provided with the friction pad 33a on the upper surface side. A compression spring 47 is provided below the separation pad member 33, and a compression spring 52 is provided between the bottom plate 32 and the structure 34.

  In the separation pad member 33, the friction pad 33a is formed of a material having a high friction coefficient such as rubber, rubber cork, urethane foam, and thermoplastic elastomer. Further, the downstream side of the separation pad member 33 in the paper feeding direction (the side opposite to the paper entering direction) is rotatably supported by the support shaft 33b.

  Note that reference numeral 60 in FIG. 6 denotes a leading edge detection sensor for the paper P, which detects that the leading edge of the paper P enters or exits the nip portion N.

  FIG. 7 is an explanatory diagram of the paper feeding operation in the paper feeding device of the present embodiment. During feeding, the bottom plate 32 on which the paper P is stacked is pressed against the retracted position indicated by the solid line in FIG. As described above, the sheet P is moved to the position, and the sheet P is pressed against the lower surface of the sheet feeding roller 31. By rotating the sheet feeding roller 31 in this state, the upper layer sheet P is fed in the direction of the nip portion N between the sheet feeding roller 31 and the friction pad 33a. If the fed paper P is one sheet, it passes through the nip portion N by the rotation of the paper feeding roller 31 and is sent downstream in the paper feeding direction. However, when the paper P is double-fed, the lower layer paper P is prevented from moving by the friction pad 33a in the nip portion N, and the upper layer paper P receives the rotational force of the paper feed roller 31 to be the lower layer paper. The sheet is slid on the sheet P and sent downstream in the sheet feeding direction, and separated sheet feeding is performed.

  The bottom plate 32 is driven to move between the pressure contact position and the retracted position for each sheet P of paper P, and is in the retracted position when not operating. Thus, when the bottom plate 32 is in the retracted position, the operator can easily set the sheets P on the bottom plate 32.

  As shown in FIG. 8, a motor 55 as a single drive source is provided with a drive pulley 57 instead of the output gear 56 shown in FIG. 3, and a driven pulley 58 is substituted for the chipped gear 39. It is also conceivable that a transmission belt 59 is installed between the driving pulley 57 and the driven pulley 58 and the sheet feeding roller shaft 35 is rotated intermittently as described above.

  By the way, the configuration of the present embodiment is different from the regular type configuration in which the sheet on the bottom plate is always in contact with the sheet feeding roller during sheet feeding, and the sheet feeding roller 31 and the sheet P by the bottom plate 32 moving up and down. Since the contact / separation of each sheet is accompanied by each sheet, the variation of the sheet feeding / separation characteristic is large, and a conveyance defect is likely to occur. In particular, multi-sheet feeding (double feeding) of the paper P is a concern. One reason for this is that when the bottom plate 32 is completely lifted, an impact is generated by the bottom plate 32 colliding with the sheet feeding roller 31, and the separation performance is degraded due to the impact (specifically, the sheet feeding roller is lowered due to the impact when the bottom plate 32 is raised. 31), an upward force is applied, and the separation pressure is released, so that the paper P is likely to penetrate through the nip portion N in a bundled state. In addition, noise at the time of the rising impact of the bottom plate 32 also becomes a problem.

  Therefore, in the present embodiment, the above problem is solved by controlling the driving rotation speed of the motor 55 that operates the paper feed roller 31 and the bottom plate 32.

  FIG. 9 is a timing chart relating to the driving of the sheet feeding roller and the bottom plate in the first embodiment of the sheet feeding apparatus according to the present invention, and the sheet feeding is performed under the control of a CPU (Central Processing Unit) which will be described later. A motor 55 that operates the sheet feeding roller 31 and the bottom plate 32 via the roller shaft 35 and the cam 38 is configured to reduce the moving speed of the bottom plate 32 and the rotation speed of the sheet feeding roller 31 during the ascending period of the bottom plate 32. I try to control it.

  FIG. 10 is a block diagram showing a schematic configuration of the bottom plate control system in the present embodiment. Reference numeral 70 denotes detection data from the tip detection sensor 60 or various sensors S to be described later, and display / operation panel input. The CPU is a control unit that receives various setting data from the output unit 71 and outputs a control drive signal for controlling each unit. The CPU 70 outputs a control drive signal to a motor speed variable / drive unit 72 that performs start / stop control of the motor 55 and speed increase / decrease control.

  As shown in FIG. 9, in the first embodiment, the CPU 70 decelerates the rotation of the motor 55 every time paper feeding is started (time point a), and when the lifting is completed from the start of rising of the bottom plate 32 (time point b) ( c), the moving speed of the bottom plate 32 and the rotational speed of the paper feed roller 31 are decelerated from a predetermined speed (normal speed), and the leading edge of the paper P is monitored by the leading edge detection sensor 60. 6 is decelerated until it enters the nip portion N shown in FIG. 6 (time point d), and then the moving speed of the bottom plate 32 and the rotational speed of the paper feed roller 31 are returned to the normal speed.

  In this way, by lowering the rising speed of the bottom plate 32, it is possible to suppress a decrease in separation performance due to an impact, to suppress the occurrence of double feed, and to reduce noise during the rising impact of the bottom plate 32. it can. Moreover, by lowering the rotational speed of the paper feed roller 31 when the bottom plate 32 is raised and the paper P comes into contact with the paper feed roller 31, the clamping state of the paper P at the separation nip portion N is ensured, and the paper Slip can be suppressed. Furthermore, since the motor 55 as a drive source is single, cost reduction and space saving can be achieved.

  FIG. 11 is a timing chart relating to the driving of the sheet feeding roller and the bottom plate in the sheet feeding device according to the second embodiment of the present invention, and the rotation of the motor 55 is decelerated every time sheet feeding is started (time point a). From the time when the bottom plate 32 starts to rise (time point b) to the time point when the leading edge of the paper P passes through the nip portion N (time point c), the motor 55 is rotated to the normal speed.

  By doing so, by decelerating until the leading edge of the paper P passes through the nip portion N, the contact of the paper P with the paper feed roller 31 and the separation conveyance at the nip portion N are stabilized. Since the load fluctuation is reduced, the load on the motor 55 is reduced and stable driving and control are performed.

  Further, by making the deceleration state adjustable, the balance between the double feed due to the deceleration of the rising section of the bottom plate 32 or the noise suppression effect and the noise suppression effect reduction by not decelerating at the nip portion N can be achieved with paper. It becomes possible to adjust according to uses such as seeds.

  Furthermore, the timing of releasing the deceleration can be switched between before the leading edge of the paper P enters the nip portion N and after it has come out, thereby balancing the noise suppression effect and the load fluctuation suppression. It becomes possible to adjust according to.

  These adjustments can be performed by the user from the operation panel of the image forming apparatus shown in FIG. 1 or the screen of a personal computer (not shown).

  FIG. 12 is a timing chart relating to the driving of the sheet feeding roller and the bottom plate in Embodiment 3 of the sheet feeding apparatus according to the present invention, and the rotation of the motor 55 is decelerated every time sheet feeding is started (time point a). From the time when the bottom plate 32 starts to rise (time point b) to the time when it is completed (time point c), the base plate 32 is decelerated. Thereafter, the speed is increased until the leading edge of the paper P passes through the nip portion N (time point d) by the amount of deceleration, and this speed-up period corresponds to the speed-down period so that the entire processing time does not become longer.

  In this way, the time required for the sheet P to reach from the start of feeding to an arbitrary part in the sheet feeding path (for example, between the manual feed tray 8 and the registration roller 19 in the apparatus shown in FIG. 1) is made constant. In addition, by changing (accelerating) the speed in the deceleration release section in accordance with the speed change in the deceleration section, it is possible to prevent the entire processing time from changing even if the paper is decelerated in a part of the paper feed path. It is possible to maintain productivity.

  FIG. 13 is a cross-sectional view showing the main part of the paper feeding device for manual paper feeding in the present embodiment. In the vicinity of the separation pad member 33, the position (high height) of the uppermost paper P placed on the bottom plate 32 is shown. A sensor S for detecting (direction) is installed.

  In response to the detection information of the sensor S, the deceleration is started immediately before the bottom plate 32 rises and the sheet feeding roller 31 and the sheet P come into contact with each other, thereby reducing the deceleration section as much as possible and increasing the productivity accordingly. be able to.

  As shown in FIG. 14, the sensor S includes a filler 61 that rotates when the paper P is raised and a transmissive photointerrupter 62 whose detection optical path is blocked by the filler 61. 15 is configured by a pressure sensor (load cell) 63 that is installed in the moving range of the paper P and detects the rise of the paper P, or, as shown in FIG. 16, a light emitting element and a light receiving element are provided. It is conceivable to install the reflection type photo interrupter 64 provided to detect the rising of the paper P by the incidence of light on the paper P and the reflection of light from the paper P.

  However, since the height of the top sheet on the bottom plate 32 may vary, such as when the sheet P is curled, as shown in FIG. It is conceivable that the bottom plate 32 is not a sheet P but a rigid body with little height variation, and a bottom plate detection sensor 65 for detecting the position of the bottom plate 32 is disposed in the vicinity of the lower portion of the separation pad member 33.

  Further, since the impact when the bottom plate 32 is raised is large when the paper stacking amount is small (when the paper stacking amount is large, the paper becomes an impact reducing material), as shown in FIG. Thus, the sensor detection position is set to a position immediately before the completion of the rise of the bottom plate 32 when the paper stacking amount is small, and when this is detected, that is, only when the paper stacking amount is small, the bottom plate rising speed is set. By controlling so as to decrease, a decrease in productivity can be avoided.

  FIG. 19 is a timing chart relating to the driving of the paper feeding roller and the bottom plate in the fourth embodiment of the paper feeding apparatus according to the present invention. The fourth embodiment is basically the same as the driving timing in the first embodiment. After completion of the rising of 32 (time point c), before the time point (time point d) when the leading edge of the paper P enters the nip portion N (for example, the distance between the registration roller 19 and the nip portion N, the paper conveyance speed, etc.) This is different from the first embodiment in that the rotational drive of the motor 55 is temporarily stopped (at time e).

  By doing so, when the bottom plate 32 rises and an impact occurs, the conveyance of the paper P is temporarily stopped, and the conveyance can be resumed after the influence of the impact is subsided, and the conveyance quality can be stabilized. .

  In addition, by allowing the user to adjust the stop time from an operation panel such as the image forming apparatus shown in FIG. 1 or a personal computer screen, the stop time can be adjusted according to the type of paper used. Is possible.

  The configuration of the above-described embodiment of the paper feeding device according to the present invention is appropriately employed in the manual feed tray 8 or the like in the image forming apparatus shown in FIG. Since the paper feeding is stable, highly reliable image formation is realized.

  The present invention is used in a paper feeding device that feeds recording paper to an image forming unit such as a copying machine or a printer, and has a configuration in which a bottom plate moves up and down once with respect to a paper feeding roller each time one paper is fed. The sheet feeding device is effective as a sheet feeding device that can suppress a decrease in separation performance, generation of noise, slip at a sheet separation nip, and the like, and is particularly applicable to a sheet feeding device for manual feeding.

1 is a configuration diagram of an electrophotographic tandem color copier for explaining an embodiment of the present invention. (A), (b) is the perspective view which extracts and shows the said paper feeding apparatus part in the state which opened the openable / closable manual feed tray which also serves as a cover in FIG. FIG. 2 is a perspective view showing a paper feeding device by removing a manual tray and a member that guides the fed paper in FIG. The perspective view which shows the pressurization plate which is a part of paper feeder in FIG. The perspective view which shows the pressurization board in FIG. 4 from the back side Sectional drawing which shows the principal part of the paper feeding apparatus for manual feeding which is Embodiment 1 of the paper feeding apparatus which concerns on this invention Explanatory drawing of the paper feeding operation in the paper feeding device of the first embodiment. The perspective view which shows the other rotational drive structure of the paper-feed roller shaft in this embodiment Timing chart regarding driving of sheet feeding roller and bottom plate in Embodiment 1 of sheet feeding apparatus according to the present invention The block diagram which shows schematic structure of the baseplate control system in this embodiment Timing chart regarding driving of sheet feeding roller and bottom plate in embodiment 2 of sheet feeding apparatus according to the present invention Timing chart regarding driving of sheet feeding roller and bottom plate in embodiment 3 of sheet feeding apparatus according to the present invention Sectional drawing which shows the principal part of the paper feeding apparatus for manual paper feeding in this embodiment Sectional drawing which shows the transmissive photo interrupter which detects the position of the bottom board top paper in this embodiment Sectional drawing which shows the pressure sensor (load cell) which detects the position of the baseplate top paper in this embodiment Sectional drawing which shows the reflection type photo interrupter which detects the position of the baseplate top paper in this embodiment Sectional drawing which shows the sensor which detects the position of the height direction of the baseplate in this embodiment Sectional drawing which shows the sensor which detects the position just before completion of a baseplate raise | lifting when the paper loading amount in this embodiment is small Timing chart regarding driving of sheet feeding roller and bottom plate in embodiment 4 of sheet feeding apparatus according to the present invention

Explanation of symbols

8 Manual Tray 31 Paper Feed Roller 32 Bottom Plate 32a Arc-shaped Projection 33 Separation Pad Member 33a Friction Pad 35 Paper Feed Roller Shaft 38 Cam 39 Chipped Gear 55 Motor 56 Output Gear 57 Drive Pulley 58 Driven Pulley 59 Transmission Belt S Sensor 60 Tip Detection Sensor 61 Filler 62 Transmission type photo interrupter 63 Pressure sensor (load cell)
64 Reflection type photo interrupter 65 Bottom plate detection sensor 70 CPU
72 Speed Variable / Drive N Nip Part P Paper S Sensor

Claims (14)

In a paper feed roller for feeding paper, a bottom plate that presses the loaded paper against the paper feed roller, and a separation nip portion with the paper feed roller on the downstream side of the paper feed direction from the bottom plate A separation member that separates and conveys the sheets one by one, and a bottom plate elevating member that moves the bottom plate so that the sheet and the sheet feeding roller are brought into contact with and separated each time the sheet placed on the bottom plate is fed once. In a paper feeding device equipped with
A control unit that controls a single drive source that operates the paper feed roller and the bottom plate elevating member so that the moving speed of the bottom plate and the rotational speed of the paper feed roller are decelerated during the ascending period of the bottom plate; A paper feeding device characterized by comprising.   The sheet feeding device according to claim 1, wherein the driving source is decelerated from the start of the rising of the bottom plate until the leading edge of the sheet passes through the separation member.   The sheet feeding device according to claim 1, wherein the deceleration can be adjusted.   The sheet feeding device according to any one of claims 1 to 3, wherein the deceleration release timing can be switched between before and after the leading end of the sheet enters the separating member.   2. The speed in the deceleration release section is changed in accordance with the speed change in the deceleration section so that the time required for the sheet to reach an arbitrary part in the sheet feeding path from the start of feeding is constant. The sheet feeding device according to any one of?   The position of the uppermost paper in the height direction of the paper placed on the bottom plate is detected by a sensor, and the deceleration is started before the bottom plate rises and the paper supply roller contacts the paper. The sheet feeding device according to claim 1 or 2, characterized in that   The sheet feeding device according to claim 6, wherein the sensor is an optical detection sensor.   8. The paper feeding device according to claim 7, wherein the optical detection sensor comprises a transmissive photo interrupter or a reflective photo interrupter.   The sheet feeding device according to claim 6, wherein the sensor includes a load cell.   The sheet feeding device according to claim 1, further comprising a sensor that detects a rising height of the bottom plate.   11. The sheet feeding device according to claim 10, wherein the sensor that detects the rising height of the bottom plate detects a height immediately before completion of the rising of the bottom plate when the sheet stacking amount is small.   The paper feeding device according to any one of claims 1 to 11, wherein when the raising of the bottom plate is completed, the driving source is temporarily stopped.   13. The sheet feeding device according to claim 12, wherein a time for stopping the driving source is variable. An image forming apparatus that feeds sheets one by one from a sheet feeding unit to an image forming unit and forms an image on the sheet by the image forming unit.
An image forming apparatus comprising the paper feeding device according to claim 1 as the paper feeding unit.

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