JP2007137559A - Paper feeding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently and stably perform separation feeding by preventing overlapping feeding easily generated in a constitution that a bottom plate for piling up papers in every one sheet of paper to be fed is moved between a position where the paper is brought into pressure contact with a paper feed roller and a position retreated from the position. <P>SOLUTION: A projected guide member 55 is projectedly provided on a paper feed route of the paper P fed from above a manual insertion tray 8 and near a separation pad member 33 on a conveying guide plate 34a for guiding a lower surface side of the fed paper P. Further, a distal end 55a of the projected guide member 55 is projected into the paper feed route in the state that it becomes higher than height of a paper intrusion guide part 33c of the separation pad member 33 at contact of the paper feed roller 31 and a friction pad 33a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding roller for feeding a sheet, and a sheet feeding device including a bottom plate and a separation pad member movable with respect to the sheet feeding roller, and in particular, a technique for preventing sheet multi-feeding. It is about.

  2. Description of the Related Art In a paper feeding device in 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 compatible with paper that allows a wide variety of paper types to pass. . Among them, low-cost friction pad separation type structures have been conventionally employed (see Patent Documents 1 to 4).

  In addition, as a configuration of the friction pad separation method, a common one is a paper that is placed by a sheet feeding roller (roller) and a friction pad as a separation pad member contacting each other at a nip portion with a predetermined nip pressure. The bottom plate that presses against the paper feed roller always has a structure in which the bottom plate is 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. However, there is a configuration in which it is located at the retracted position when not operating.

  The latter friction pad separation method will be described with reference to FIG.

  In FIG. 14, reference numeral 101 denotes a paper feed roller that rotates in the clockwise direction to feed the paper P, and 102 has one end rotatably supported by a support shaft 103, and a friction pad 104 is provided on the other end upper side. In addition, a plate-like separation pad member 105 that is elastically contacted at the nip portion N with the sheet feeding roller 101 by an urging unit (not shown) is a pressure contact position and a retracted position with respect to the sheet feeding roller 101 by a driving unit (not shown). It is a bottom plate that is driven to move between and the sheets P are stacked on the upper surface.

  At the time of paper feeding, the bottom plate 105 on which the paper P is stacked is moved from the retracted position indicated by the solid line in FIG. 14 to the pressure contact position indicated by the two-dot chain line to press the paper P against the lower surface of the paper supply roller 101. By rotating the sheet feeding roller 101 in this state, the upper layer sheet P is fed in the direction of the nip portion N between the sheet feeding roller 101 and the friction pad 104. If the fed paper P is one sheet, it passes through the nip portion N by the rotation of the paper feed roller 101 and is sent downstream in the paper feed direction. However, when the paper P is double-fed, the lower layer paper P is prevented from moving by the friction pad 104 at the nip portion N, and the upper layer paper P receives the rotational force of the paper feed roller 101, so that the lower layer paper P It slides on P and is sent downstream in the paper feeding direction.

The bottom plate 105 is driven to move between the pressure contact position and the retreat position for each sheet P fed, but is in the retreat position when not operating. Thereby, when the bottom plate 105 is in the retracted position, the operator can easily set the sheets P on the bottom plate 105.
Japanese Utility Model Publication No. 1-111641 Japanese Patent Laid-Open No. 5-278884 JP 2000-128379 A JP 2005-255360 A

  However, in the paper feeding device having the configuration shown in FIG. 14, when the paper P is double-fed to the separation pad member 102 as shown in FIG. The separation pad member 102 may be rotated by receiving a downward force away from the sheet feeding roller 101 due to the reaction force due to the stiffness of P1 or the paper weight.

  In particular, in the paper feeding device having the configuration shown in FIGS. 14 and 15, the bottom plate 105 is lowered to the retracted position when the upper layer paper P1 is fed upstream from the bottom plate 105 in the paper feeding direction. The end on the bottom plate 105 side of P1 and P2 hangs down, and the end (A portion) of the separation pad member 102 on the bottom plate 105 side is pushed down by the sheets P1 and P2, and the nip portion N tends to open. become.

  For this reason, a predetermined separation pressure (nip pressure) does not occur in the nip portion N between the paper feeding roller 101 and the friction pad 104, and therefore, proper separation paper feeding does not act in the nip portion N, and the lower layer paper P2 does not work. There may be a double feed that is fed along with the upper layer paper P1.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and in the case of feeding a thick sheet, in particular, the bottom plate moves between the retracted position and the pressed position for each sheet to be fed. It is an object of the present invention to provide a paper feeding device that prevents double feeding that is likely to occur in a product, and that allows separation and paper feeding to be performed in a good and stable manner.

  In order to achieve the above object, the invention according to claim 1 is movable to a paper feed roller for feeding paper, a pressure contact position for pressing the placed paper against the paper feed roller, and a retracted position. And a separation pad member that is provided so as to be able to come into contact with and separate from the sheet feeding roller on the downstream side in the sheet feeding direction from the bottom plate and separates sheets fed one by one at a nip portion with the sheet feeding roller A projecting guide member that is in contact with the lower surface of the sheet fed to the nip portion and receives the sheet so as to be movable and restrain drooping of the sheet, in the vicinity of the separation pad member. This configuration is characterized in that a plurality of sheets are fed, and a force that causes the sheets to hang down from the separation pad member and push down the separation pad member is caused by the protruding guide member. Receiving It is will be escaping, and stable state of the nip portion is always separated feeding is carried out in good and stable condition.

  According to a second aspect of the present invention, in the paper feeding device according to the first aspect, the protruding guide member is a pressure maintaining member that maintains the nip pressure of the nip portion in contact with the lower surface of the paper fed to the nip portion. According to the present invention, this configuration makes it possible to always maintain the separation sheet feeding in a good and stable state by maintaining and stabilizing the nip pressure of the separation pad member.

  According to a third aspect of the present invention, in the paper feeding device according to the first aspect, the protruding guide member is in contact with the lower surface of the paper fed to the nip portion to prevent the paper from being displaced from the paper feeding path. By being a blocking member, this configuration prevents the separation pad member from being displaced due to the displacement of the paper, thereby making it possible to always make the separation paper feed in a good and stable state.

  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 protruding guide member is installed upstream of the nip portion in the paper feeding direction. It is possible to prevent the separation pad member from being pushed down by the thick paper on the upstream side and to prevent a plurality of papers from entering the nip portion.

  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 protruding guide member is projected into a paper feeding path passing through the nip portion. Thus, it is possible to effectively prevent the separation pad member from being pushed down.

  According to a sixth aspect of the present invention, in the paper feeding device according to any one of the first to fifth aspects, when the protruding guide member is in contact with the paper feeding roller and the separation pad member, the paper entry side end of the separation pad member It is characterized in that it is installed so as to protrude into the paper feed path from the section, and this configuration can reliably prevent the separation pad member from being pushed down.

  According to a seventh aspect of the present invention, in the paper feeding device according to any one of the first to sixth aspects, the protruding guide members are arranged at symmetrical positions on both sides of the separation pad member. Further, it is possible to prevent the occurrence of problems such as skew by changing the balance of the sheet feeding state due to the presence of the protruding guide member.

  According to an eighth aspect of the present invention, in the paper feeding device according to any one of the first to seventh aspects, between the horizontal virtual extension lines between the tip of the protruding guide member and the lower portion of the paper feeding roller in the paper feeding path. This structure is characterized in that a plurality of sheets can be prevented from entering the nip portion due to the gap between the protruding guide member and the sheet feeding roller.

  According to a ninth aspect of the present invention, in the paper feeding device according to any one of the first to eighth aspects, the protruding guide member is formed of a low friction material. An increase in paper feeding load due to frictional resistance can be prevented.

  According to a tenth aspect of the present invention, in the paper feeding device according to any one of the first to ninth aspects, the protruding guide member is formed of a wear-resistant material. With this configuration, the protruding guide member is worn away. Can be prevented.

  According to an eleventh aspect of the present invention, in the paper feeding device according to any one of the first to tenth aspects, the height of the protruding guide member can be adjusted. By setting the height of the protruding guide member in accordance with the thickness of the paper, it is possible to prevent the leading edge of the paper from being bent.

  According to a twelfth aspect of the present invention, in the paper feeding device according to any one of the first to eleventh aspects, a paper guide roller is provided on the protruding guide member. It is possible to prevent an increase in paper feeding load due to the frictional resistance of the paper.

  According to a thirteenth aspect of the present invention, in the paper feeding device according to any one of the first to twelfth aspects, the inclination angle of the upper end portion of the protruding guide member is formed to be substantially the same as the paper entry angle to the nip portion. With this configuration, it is possible to suppress an increase in the paper feeding load and smoothly allow the paper to enter the nip portion.

  According to a fourteenth aspect of the present invention, in the paper feeding device according to any one of the first to seventh aspects, the separation pad member extends to the lower surface side of the paper feeding roller, and can be rotated on the side opposite to the paper entering direction. The friction pad is provided on the upper surface on the nip portion side with the paper feed roller, and this is particularly effective when the separation pad member having such a configuration is installed.

  A fifteenth aspect of the present invention is the conveyance guide member for conveying and guiding the paper after passing through the nip portion above the nip portion in the paper feeding device according to any one of the first to sixth, thirteen, and fourteenth aspects. Even when the paper transport path rises steeply and the rear edge of the paper is easy to push down the separation pad member, the above-mentioned action makes the separation feeding well. Is called.

  According to the present invention, since a plurality of sheets are fed, and the force that the sheets hang from the separation pad member and push the separation pad member down can be received by the protruding guide member, the separation pad member can be released. Since the state of the nip portion is stable, the nip pressure of the nip portion can be maintained, and the suspension of the paper from the separation pad member can be prevented, thereby preventing the nip portion from opening. Separation feeding is always performed in a good and stable state.

  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 to irradiate image information with laser light. 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 and collects the toner remaining on the surface of the photoconductor 11 after transfer. .

  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.

  FIGS. 2A and 2B are perspective views showing the paper feeding device 30 extracted with the manual feed tray 8 opened in FIG. 1, and FIG. 3 shows the manual feed tray 8 and the fed paper P. FIG. 4 is a perspective view showing a pressure plate that is a part of the paper feed 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 separation pad member 33 provided with a friction pad 33a that separates the paper P to be fed one by one in contact with the lower surface of the paper feeding roller 31 on the downstream side in the paper feeding direction from the bottom plate 32. Etc.

  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.

  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 by a plane parallel to the center line (see FIG. 3), and the roller portion 31a and the cutout portion 31b having a circular outer peripheral surface. And have. 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).

  A fan-shaped cam 38 is fixed to both ends of the paper feed 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 but has a shape in which a part of a circular gear is cut out. When the chipped gear 39 and an input gear (not shown) mesh with each other, the feed roller shaft 35 and the feed gear 39 are fed. The paper roller 31 rotates. When the input gear faces the cut-out portion of the chipped gear 39, transmission of the driving force from the input gear 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.

  A paper feed roller position restricting member 40 is fixed to the other end side of the paper 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 input gear 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. Then, 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 input gear by this rotation.

  When the chipped gear 39 meshes with the input gear, the chipped gear 39 rotates substantially once until the position where the input gear does not mesh with the chipped gear 39 again, and the sheet feeding roller 31 also rotates approximately once. The solenoid 43 is turned off and the flapper 43 is locked to the first protrusion 41 when the chipped gear 39 rotates approximately once and the chipped gear 39 and the input gear are not meshed with each other. 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 made of resin, and arc-shaped protrusions 32a facing the cams 38 are formed on both sides in the direction orthogonal to the paper feeding direction of the paper P and outside the stacking range of the paper P. A guide roller 48 that is in contact with the peripheral edge of the cam 38 is attached to the 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, and the guide pins 50 are provided on both sides of the bottom plate 32 in the direction orthogonal to the paper feed direction of the paper P. A guide hole 51 through which 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.

  A conical compression spring 52 is attached between the bottom plate 32 and the structure 34 as pressure means for pressing the bottom plate 32 toward the paper feed roller 31. 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 moved by switching the solenoid 43 on and off and transmitting the driving force from the input gear to the chipped gear 39. Is driven to rotate. 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.

  In the present embodiment, as shown in FIG. 2B, a conveyance guide that guides the lower surface side of the paper P that is the paper feeding path of the paper P that is fed from the manual feed tray 8. Protruding guide members 55 project symmetrically near both sides of the separation pad member 33 on the plate 34a. The leading end portion 55a of the protruding guide member 55 is provided so as to protrude higher than the height of the paper entry guide portion 33c of the separation pad member 33 when the paper feed roller 31 and the friction pad 33a are in contact with each other.

  FIG. 7 is an explanatory diagram of a sheet feeding operation in the sheet feeding device according to the first embodiment. When feeding, the bottom plate 32 on which the sheets P are stacked is pressed by a two-dot chain line from a retracted position indicated by a 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.

  By the way, as shown in FIG. 8, when the paper P is double fed to the separation pad member 33, conventionally, as shown in FIGS. 14 and 15, when the preceding upper layer paper P1 is a thick paper, The separation pad member 33 may be rotated by receiving a downward force away from the paper feed roller 31 due to the reaction force due to the stiffness or paper weight of the paper P1, but in this embodiment, the nip portion The leading end of the protruding guide member 55 that protrudes into the paper feeding path from the paper entry guide portion 33c has a force that the thick paper to which N is fed pushes down the paper entry guide portion 33c of the separation pad member 33. The portion 55a can be eliminated by receiving the underside of the paper P and letting it escape.

  In this way, the paper entry guide portion 33c is not pushed down by the paper P, so that the nip portion N between the paper supply roller 31 and the separation pad member 33 is not opened, and an appropriate separation pressure (nip pressure) is always applied. As a result, double feeding can be suppressed. In this way, in order to suppress the stiffness of thick paper, there is no change in the characteristic value such as an increase in the separation pressure. Therefore, a wide variety of paper types can be easily handled.

  As in the prior art, also in this embodiment, when the upper layer paper P1 is fed upstream from the bottom plate 32 in the paper feeding direction, the bottom plate 32 descends to the retracted position, so that the bottom plate 32 side of the paper P1, P2 hangs down. However, even when the bottom plate 32 is lowered, the leading end portion 55a of the protruding guide member 55 receives the sheets P1 and P2, and the nip portion N of the separation pad member 33 is not opened. For this reason, an appropriate separation pressure is always generated at the nip portion N between the sheet feeding roller 31 and the friction pad 33a, so that satisfactory separation sheet feeding is performed.

  In other words, the protruding guide member 55 functions as a pressure maintaining member that is in contact with the paper P fed to the nip portion N and maintains the nip pressure of the nip portion N. Further, the projecting guide member 55 reduces the drooping displacement of the paper P from the paper feed path. Since it functions as a blocking member for blocking, it is possible to always make the separated paper feed good and stable.

  In this way, by suppressing the push-down of the protruding guide member 55, as shown in FIG. 8, after passing through the nip portion N through the paper feed path of the paper P, the paper is guided up by abruptly rising upward. It is possible to install conveyance guide members such as the guide plate 56 and the conveyance roller 57. This increases the degree of freedom in designing the paper feed / conveyance path. Further, it is possible to suppress an increase in the conveyance load at the separation pad member 33 due to the stiffness of the thick paper, and it is possible to reduce the conveyance load at the nip portion N due to the stiffness of the thick paper, especially when the number of thick paper sheets is large. It becomes.

  In the present embodiment, the protruding guide member 55 is provided on the upstream side in the paper feeding direction with respect to the paper entry guide portion 33c of the separation pad member 33. Further, as shown in FIG. A gap K is formed between the horizontal virtual extension lines A and B in the paper feed path with the lower part of the paper roller 31. Accordingly, in addition to the effect of preventing the separation pad member 33 from being pushed down by the thick paper, it is possible to prevent the paper P from entering the nip portion N in a block shape.

  Further, by forming the protruding guide member 55 with a low friction material such as resin coating, it is possible to suppress an increase in the conveyance load due to a frictional resistance with the paper and to suppress an increase in the slip rate during paper feeding.

  Further, by forming the protruding guide member 55 from a wear-resistant material such as metal or glass fiber plastic, wear of the protruding guide member 55 due to the sliding contact of the paper is suppressed, and the effect of pressing the paper is maintained for a long time. And the effect of deterring double feed is sustained.

  Further, by forming the inclination angle of the leading end portion 55a of the protruding guide member 55 to be substantially the same as the paper entry angle to the nip portion N, it is possible to suppress an increase in paper feed load and to smoothly feed the paper to the nip portion N. It is possible to enter.

  FIG. 9 is a configuration diagram illustrating a main part of a sheet feeding device as Embodiment 2 of the present invention. In Embodiment 2, the protrusion amount of the protrusion guide member 55 can be adjusted according to the type of paper. .

  In FIG. 9, a rack 55b is provided below the protruding guide member 55. A pinion gear 58 is engaged with the rack 55b, and the pinion gear 58 is rotated by the operation lever 59, whereby the protruding guide member 55 is moved up and down via the rack 55b. It has a configuration to let you.

  According to the second embodiment, when the paper sheet thickness is thin, if the protruding guide member 55 protrudes too much with respect to the paper entry path, the entry angle to the friction pad 33a becomes large, so that the leading edge of the paper P breaks with thin paper. However, by making it possible to adjust the height of the protruding guide member 55, it is possible to suppress the side-folding side effect of thin paper.

  Further, wrinkling of the thin paper causes wrinkles and scratches on the OHP. However, when the stiffness of the paper is small, the force for pushing down the paper entry guide portion 33c of the separation pad member 33 is small. In this case, the occurrence of wrinkles and scratches can be suppressed by reducing the protruding amount of the protruding guide member 55.

  FIG. 10 is a configuration diagram showing a main part of a sheet feeding device as a third embodiment of the present invention. In the third embodiment, a paper guide roller 60 is provided at the leading end portion 55a of the protruding guide member 55. FIG.

  According to the third embodiment, when the paper thickness is increased and the force for suppressing the stiffness of the paper P is increased, the transport load on the protruding guide member 55 is increased. However, by providing the paper guide roller 60, It becomes possible to reduce the conveyance load, hold an appropriate conveyance force, and handle a wide variety of paper types. Generally, it is necessary to increase the paper feed pressure in order to maintain an appropriate conveyance force. However, according to the third embodiment, it is not necessary to change the characteristic value, and it is easy to use a wide variety of paper types. It becomes possible to respond.

  FIG. 11 is a cross-sectional view illustrating a main part of a manual sheet feeding device according to a fourth embodiment of the present invention. In the sheet feeding path on the downstream side of the sheet feeding roller 31 in the sheet feeding direction, the relay conveyance roller 61 is provided. 6 is different from the first embodiment in FIG.

  A pair of relay conveyance rollers 61 is disposed at a position close to the friction pad 33 a of the separation pad member 33 and on both sides of the separation pad member 33. In this way, by bringing the relay conveyance roller 61 as close as possible to the nip portion N, it is possible to prevent the occurrence of non-feeding during the feeding of the OHP final paper which tends to be short and the conveyance distance tends to be short. Become.

  FIG. 12 is an explanatory diagram of a configuration related to the friction pad in the present embodiment. The separation pad member 33 is formed in a substantially horizontal shape, and a bent portion 33d is formed on the application surface of the friction pad 33a in the separation pad member 33. A bent recess M is formed on the sheet passing surface of the friction pad 33a.

  As a result, the separation sheet member 33 is brought close to the horizontal shape, so that the thick paper can easily escape from the nip portion N. However, when the leading end of the paper P is hooked by the bending recess M of the friction pad 33a, the paper P becomes nip portion N. Can be prevented from penetrating through, and double feeding can be prevented.

  FIG. 13 is an explanatory diagram of another configuration relating to the friction pad in the present embodiment, and the position of the bent recess M of the friction pad 33a is set to the position of the nip N. FIG.

  As a result, when the bent concave portion M exists at a position away from the nip portion N, the leading edge of the paper P easily moves where the leading edge of the paper P moves away from the nip portion N, and the hooking effect of the paper P by the friction pad 33a. However, by setting the bent concave portion M at the position of the nip portion N, the movement of the leading edge of the paper P is restricted, so that the catching effect can be improved.

  It should be noted that the effects of the above embodiments can be made efficient by appropriately selecting and adopting the configuration according to the configuration and specifications of the apparatus.

  The present invention is used in a paper feeding device that feeds recording paper to an image forming unit such as a copying machine, a printer, and the like, and is movable relative to the paper feeding roller for feeding paper. A sheet feeding device having a bottom plate and a separation pad member is effective as a device for preventing double feeding of recording sheets, and is particularly applied 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 a perspective view showing the paper feeding device portion extracted in a state where an openable and closable manual feed tray also serving as a cover in FIG. 1 is opened. 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. Explanatory drawing when a sheet is double-fed to a separation pad member in the sheet feeding device of Embodiment 1. FIG. 5 is a configuration diagram illustrating a main part of a sheet feeding device as a second embodiment of the present invention. The block diagram which shows the principal part of the paper feeder as Embodiment 3 of this invention Sectional drawing which shows the principal part of the paper feeding apparatus for manual paper feeding which is Embodiment 4 of this invention Explanatory drawing of the structure which concerns on the friction pad in this embodiment Explanatory drawing of the other structure which concerns on the friction pad in this embodiment Description of a conventional friction pad separation type paper feeder Explanatory drawing when a sheet is double-fed to a separation pad member in a conventional friction pad separation type paper feeder

Explanation of symbols

30 Paper feeder 31 Paper feed roller 32 Bottom plate 33 Separation pad member 33a Friction pad 33b Support shaft 33c Paper entry guide portion 33d Bending portion 34 Structure 34a Conveyance guide plate 38 Cam 43 Solenoid 47 Compression spring 52 Compression spring 55 Projection guide member 55a End portion 55b Rack 56 Guide plate 57 Conveying roller 58 Pinion gear 59 Operation lever 60 Roller 61 for paper guide Relay conveying roller N Nip part M Bent concave part P Paper

Claims (15)

A paper feed roller for feeding paper, a bottom plate movable to a press-contact position where the loaded paper is brought into pressure contact with the paper feed roller, and a retracted position; and the paper feed roller downstream of the bottom plate in the paper feed direction. In a paper feeding device provided with a separation pad member that can be brought into contact with and separated from a paper roller and separates paper fed one by one in a nip portion with the paper feeding roller,
Protruding guide members that contact the lower surface of the sheet fed to the nip portion and receive the sheet so as to be movable and restrain the drooping of the sheet are provided in the sheet feeding path near the separation pad member. A paper feeder characterized by.   The sheet feeding device according to claim 1, wherein the protruding guide member is a pressure maintaining member that maintains a nip pressure of the nip portion in contact with a lower surface of a sheet fed to the nip portion.   2. The sheet feeding device according to claim 1, wherein the protruding guide member is a blocking member that contacts a lower surface of a sheet fed to the nip portion and prevents displacement of the sheet from the sheet feeding path. .   The sheet feeding device according to claim 1, wherein the protruding guide member is installed upstream of the nip portion in a sheet feeding direction.   The sheet feeding device according to claim 1, wherein the projecting guide member is projected into a sheet feeding path that passes through the nip portion.   The protruding guide member is installed so as to protrude into a paper feeding path from a paper entry side end of the separation pad member when the paper feeding roller and the separation pad member are in contact with each other. Item 6. The sheet feeding device according to any one of Items 1 to 5.   The sheet feeding device according to claim 1, wherein the protruding guide member is disposed at a symmetrical position on both sides of the separation pad member.   The paper feed according to any one of claims 1 to 7, wherein a gap is formed between horizontal imaginary extension lines of a tip of the protruding guide member and a lower portion of the paper feed roller in a paper feed path. apparatus.   The sheet feeding device according to claim 1, wherein the protruding guide member is formed of a low friction material.   The sheet feeding device according to claim 1, wherein the protruding guide member is formed of a wear-resistant material.   The paper feeding device according to claim 1, wherein the height of the protruding guide member is adjustable.   The sheet feeding device according to claim 1, wherein a paper guide roller is provided on the protruding guide member.   The sheet feeding device according to claim 1, wherein an inclination angle of an upper end portion of the protruding guide member is formed to be substantially the same as a sheet entering angle to the nip portion.   The separation pad member extends to the lower surface side of the paper feed roller, is rotatably supported on the side opposite to the paper entering direction, and has a configuration in which a friction pad is provided on the upper surface of the nip portion side with the paper feed roller. The sheet feeding device according to claim 1, wherein the sheet feeding device is provided.   The paper feeding device according to any one of claims 1 to 6, 13, and 14, further comprising a conveyance guide member that conveys and guides the sheet after passing through the nip portion above the nip portion.

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