JP6119310B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus including the sheet conveying apparatus.

  A sheet conveying apparatus for an image forming apparatus, for example, a sheet conveying apparatus using a friction separating type feeding apparatus, includes a sheet stacking plate and a holding member that biases a friction member to a feeding roller. The sheet stacking plate is a rotatable plate disposed so that the uppermost sheet is urged toward the feeding roller by pressing means such as a spring. The holding member urges the friction member toward the feeding roller by a pressing means such as a spring. The sheets fed from the sheet stacking plate by the feeding roller are separated one by one by the friction member.

  At this time, if the pressing force of the sheet stacking plate (hereinafter referred to as sheet feeding pressure) is too high, the sheet supply force increases. Then, the sheet cannot be separated by the friction member, and double feeding occurs. Further, if the sheet feeding pressure is too low, the sheet supply force becomes lower than the conveying load due to the friction member or the like, so that a non-feed that cannot feed the sheet occurs.

  On the other hand, when the pressing force of the support plate of the friction member (hereinafter referred to as separation pressure) is too low, sufficient frictional force for forming the sheet cannot be obtained, and double feeding is likely to occur. If the separation pressure is too high, abnormal noise may occur due to stick slip between the friction member and the sheet, or noise may increase due to excessive frictional force. In order to prevent these problems from occurring, it is necessary to set the sheet feeding pressure and the separation pressure in appropriate regions.

  For example, Patent Document 1 discloses a sheet feeding device including a friction pad including a pad center portion and both sides of a pad that are in contact with each other with a step at a portion of a pressing member that contacts the recording material. In this apparatus, the paper feed roller is disposed opposite to the pad central portion, and the length of the paper feed roller is shorter than the length of the pad central portion.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a paper feeding device in which both ends of the friction pad along the paper conveyance direction are cut out from the vicinity of the nip between the paper feeding roller and the friction pad to the downstream side in the paper conveyance direction. Both ends of the friction pad, which is partially cut away, are formed of a friction member having a lower hardness than the central portion of the friction pad along the sheet conveyance direction. In addition, the conveyance resistance is different between the central portion and both end portions of the friction pad.

  Patent Document 3 discloses a sheet material conveying apparatus including a feeding unit that separates and feeds sheet materials one by one. The sheet feeding means is configured to change the conveying force of the sheet material feeding and the magnitude of the separating friction force in accordance with the size of the friction coefficient of the surface of the sheet material.

  By the way, the appropriate area of the paper feed pressure / separation pressure differs depending on the paper type such as thick paper and thin paper. Usually, thick paper is strong and has a large conveying load, which tends to be disadvantageous against non-feeding. For the opposite reason, thin paper tends to be disadvantageous to double feeding. In order to prevent these problems, it is desirable to set the sheet feeding pressure high to secure the conveying force, and to set the separation pressure high to ensure separation. However, as described above, if the separation pressure is set too high, abnormal noise due to the friction member is likely to be generated. In addition, there is a problem that the sliding noise of the paper increases due to the sliding load.

  In order to make the feeding device compatible with various paper types, it is necessary to set a common aptitude area in which these are combined. However, if the corresponding width of the sheet basis weight of the feeding device is large, there may be a case where the common aptitude region does not exist.

  Accordingly, the present invention provides a stable feeding device that is quiet and does not cause double feeding or non-feeding by reducing abnormal noise and rubbing noise caused by paper vibration and enabling selection of an appropriate pressure setting. With the goal.

The sheet conveying apparatus of the present invention is a sheet feeding apparatus having a feeding unit that feeds a sheet material separated into one sheet from a sheet stacking plate on which a plurality of sheet materials can be stacked. It has a conveyance guide member that guides on the lower side of the feeding means, and a convex member having a convex shape is arranged at a position off the feeding means of the conveyance guide member, and the upper end of the convex shape member is in the pressure contact portion of the sheet material fed and the feeding means, Ri Na sheet material which is fed the feed is is positioned above the tangent to the feeding means, the conveyance guide member, said convex An opening is provided that allows the member to move in the width direction of the sheet material orthogonal to the conveying direction of the sheet material .

  According to the present invention, by applying contact pressure to the paper, it is possible to reduce vibration during paper rubbing with the friction member, to suppress the generation of noise and noise, and to deteriorate during durability. On the other hand, the convex member is replaceable.

Sectional drawing of Embodiment 1 of the sheet feeding apparatus which concerns on this invention Same front view The perspective view of Embodiment 2 of the sheet feeding apparatus concerning the present invention. Same sectional view Sectional drawing of Embodiment 3 of the sheet feeding apparatus which concerns on this invention The perspective view of Embodiment 4 of the sheet feeding apparatus concerning the present invention. Sectional drawing of Embodiment 5 of the sheet feeding apparatus which concerns on this invention Sectional drawing of Embodiment 6 of the sheet feeding apparatus which concerns on this invention Sectional drawing of Embodiment 7 of the sheet feeding apparatus which concerns on this invention Sectional drawing which shows one Embodiment of the image forming apparatus provided with the sheet feeding apparatus which concerns on embodiment of this invention

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
<Embodiment 1>
FIG. 10 is a schematic configuration diagram illustrating an example of an image forming apparatus that can be equipped with a sheet conveying apparatus according to the present invention. Note that the image forming apparatus to be implemented in the present invention is not limited to the one shown in the figure, and the image forming apparatus such as a copying machine, a facsimile apparatus, an apparatus having a function of a multifunction machine having a copying function and a facsimile function, etc. Various devices that perform the above are targeted.

  In FIG. 10, a copying machine 100 as an example of an image forming apparatus includes an automatic document feeder 110, a document reading unit 120, a sheet feeding unit 130, and an image forming unit (image forming unit) 140. The automatic document feeder 110 separates one document (for example, the uppermost document or the lowermost document) from the document bundle placed on the document tray 110a and automatically feeds it to the contact glass on the document reading unit 120. The document reading unit 120 reads the document conveyed on the contact glass by the automatic document conveyance device 110. The image forming unit 140 forms an image read by the document reading unit 120 on the sheet material fed from the paper feeding unit 130. The sheet feeding unit 130 accommodates a sheet bundle S in which a plurality of sheet materials are stacked, and feeds the sheet material S 1 positioned at the top of the sheet bundle S to the image forming unit 140. In this embodiment, the image forming unit 140 and the paper feeding unit 130 can be divided, but a configuration other than that may be used.

  The sheet feeding unit 130 is a sheet feeding cassette 150 serving as a sheet stacking member on which a plurality of sheet materials S1 are stacked, and one sheet material positioned at the top of the plurality of sheet materials S1 on the sheet feeding cassette 150. A sheet separating and feeding apparatus 160 that separates and conveys the sheet is included.

  The sheet material S1 separated and fed by the sheet separating and feeding device 160 is transported on the transport path 170, and the sheet material S1 transported on the transport path 170 is transported by the transport roller pair 180. Then, the toner image formed by the image forming unit 140 is transferred by the transfer roller 190. This toner image is thermally transferred by the fixing device 200 and discharged onto the paper discharge tray 220 by the paper discharge roller pair 210.

  The image forming unit 140 includes four image forming units 230 (230Y (yellow), 230C (cyan), 230M (magenta), 230BK (black)), an intermediate transfer belt 240 that is a transfer belt, and an exposure device 250. It is configured.

  The exposure apparatus 250 converts color-separated image data input from a personal computer, a word processor, or the like, or image data of a document read by the document reading unit 120 into a light source driving signal. Accordingly, the semiconductor laser in each laser light source unit is driven to emit a light beam.

  The image forming units 230Y, 230C, 230M, and 230BK form images of different colors (toner images). The image forming units 230Y, 230C, 230M, and 230BK are a photoconductor 260 (260Y, 260C, 260M, and 260BK) that is an image carrier that is driven to rotate in a clockwise direction, and a charging unit 270 that is disposed around the photoconductor 260. , A developing unit 280, a cleaning unit 290, and the like.

  The photoreceptor 260 is formed in a cylindrical shape and is driven to rotate by a drive source (not shown). A photosensitive layer is provided on the outer peripheral surface portion of the photoconductor 260, and a light beam indicated by a broken line emitted from the exposure apparatus 250 is spot-irradiated on the outer peripheral surface of the photoconductor 260, whereby the outer peripheral surface of the photoconductor 260 is exposed. The electrostatic latent image corresponding to the image information is written.

  The charging unit 270 uniformly charges the outer peripheral surface of the photoconductor 260, and a contact type is used for the photoconductor 260. The developing unit 280 supplies toner to the photoconductor 260, and the supplied toner adheres to the electrostatic latent image written on the outer peripheral surface of the photoconductor 260. As a result, the electrostatic latent image on the photoconductor 260 is visualized as a toner image, and a non-contact type is adopted for the photoconductor 260.

The cleaning unit 290 cleans residual toner adhering to the outer peripheral surface of the photoconductor 260 and employs a brush contact type in which a brush contacts the outer peripheral surface of the photoconductor 260.

  The intermediate transfer belt 240 is composed of an endless belt formed with a resin film or rubber as a base. The toner image formed on the photoreceptor 260 is transferred, and the toner image transferred to the intermediate transfer belt 240 is transferred to the sheet material S1 by the transfer roller 190.

FIG. 1 is a cross-sectional view of an embodiment of a sheet feeding apparatus according to the present invention. FIG. 2 is a front view of the sheet feeding apparatus according to the present embodiment.
A plurality of sheet materials 7 stacked on the sheet stacking plate 2 are biased by a spring 3 with respect to a feeding roller 1 serving as a feeding unit. The sheet stacking plate 2 can be rotated in the vertical direction in the figure, and is always urged against the feeding roller 1 without being limited to the stacking amount of the sheet material 7. Further, when the friction member 4 on the holding member 5 is pressed against the feeding roller 1 by the pressing force of the spring 6 and the sheet material 7 is fed from the sheet stacking plate 2 to the friction member 4, the sheet A constant frictional force can be applied to the material 7. Even when two sheet materials 7 are fed to the press contact portion between the feeding roller 1 and the friction member 4, the one sheet material 7 can be separated by the frictional force.

  The sheet material 7 separated into one sheet is conveyed while being guided by the guide surface 13 of the conveyance guide member 8. At this time, the sheet material 7 is always in sliding contact with the friction member 4, and abnormal noise can be generated by the friction force. The sound may increase and become noise. In order to prevent this, the conveyance guide member 8 is provided with a convex member 9, and the upper end side of the convex member 9 is always brought into contact with the sheet material 7, thereby reducing the vibration of the sheet material 7. The convex member 9 may be separate from the conveyance guide member 8 as shown in the figure, or may be integrated.

  As shown in the drawing, the upper end surface of the convex member 9 is configured with an inclined surface on the upstream side in the conveyance direction, which is the sheet material feeding direction. The angle between the inclined surface and the tangent line where the sheet material and the feeding roller 1 are in contact is, for example, 45 degrees or less. A curved surface portion is formed at the upper end of the convex member 9 following the inclined surface.

  A tangent drawn to the feeding roller 1 from the sheet feeding nip 10 (pressure contact point between the feeding roller 1 and the sheet material 7 loaded on the sheet stacking plate 2) substantially coincides with the conveyance path of the sheet material 7. Therefore, the shape and arrangement of the convex member 9 are determined so that the upper end of the convex member 9 is above the tangent line. Thus, the sheet material 7 always comes into contact with a part of the upper end portion of the convex member 9 during conveyance.

<Embodiment 2>
In the width direction of the sheet material 7 (the direction orthogonal to the conveyance direction of the sheet material 7), the convex member 9 is disposed beside the holding member 5, and the sheet material 7 is stiff as illustrated. Thereby, the vibration generated in the friction member 4 can be suppressed by the convex member 9. The upper end of the convex member 9 always rubs against the sheet material 7 and wears.

  Therefore, as in the embodiment shown in FIGS. 3 and 4, the conveyance guide member 8 is configured as a separate part and can be replaced. Furthermore, the convex-shaped member 9 can be comprised with a material with high slidability by comprising by another member.

  Although a detailed illustration is omitted in the conveyance guide member 8, a through hole is opened, and the convex member 9 is attached through the guide surface 13 using this. On the upper side of the guide surface 13 of the convex member 9, a pair of stopper portions 9 a that protrude to both sides along the guide surface 13 are provided. In addition, protrusions 8b and 9b extending downward are provided on portions of the conveying guide member 8 and the convex member 9 located below the guide surface 13 respectively. The protrusion 9b of the convex member 9 is provided with a pair of claw portions 9c that are hooked to the lower end of the protrusion 8b to determine the position of the convex member 9. The convex member 9 can be attached to and detached from the conveyance guide member 8 by narrowing the claw portions 9c and 9c so as to approach each other.

<Embodiment 3>
Moreover, the structure which attaches the roller 15 which is a rotary body which can rotate to an upper end like embodiment shown in FIG. 5, and can reduce a sliding load can be taken. Also in this configuration, as shown in FIGS. 3 and 4, the convex member 9 may be attached through the guide surface 13.

<Embodiment 4>
FIG. 6 shows a configuration of an embodiment for preventing a conveyance failure of cardboard. In the configuration of the embodiment shown in FIG. 3 and FIG. 4, when the sheet material 7 is stiffened as shown in FIG. 2, there is no problem with plain paper, but with thick paper, bending as shown in FIG. 2 hardly occurs. For this reason, a conveyance failure may occur. A configuration for solving this will be described below.

  If the convex member 9 is fixed to the conveyance guide member 8, the paper cannot be bent between the paper feed nip 10 and the convex member 9 when the thick paper is passed, and the conveyance becomes impossible. Therefore, in the configuration of the embodiment shown in FIG. 6, the convex member 9 is movable. Therefore, the conveyance guide member 8 has a guide groove 8 a that can move in the width direction of the sheet material 7. The position of the convex member 9 can be adjusted by the user. For this reason, when the abnormal sound due to the vibration of the sheet material 7 is taken into consideration, it is possible to reduce the pressing amount of the convex member 9 for the thick paper that is originally difficult to vibrate.

  In consideration of the influence on the conveyance failure, it is desirable to keep away from the paper feed nip 10. Therefore, the configuration is such that the convex member 9 of plain paper and thick paper can be adjusted from the position indicated by reference numeral 9A in the drawing to the position indicated by reference numeral 9B. The position adjustment of the convex member 9 of the present embodiment may be performed not only by manual switching by the user, but also by an automatic switching mechanism using a solenoid or the like corresponding to the print instruction information.

<Embodiment 5>
In the configuration shown in FIG. 7, the convex member 9 is configured to be movable in the vertical direction, and is biased in a direction (feeding roller 1 side) opposite to the sheet conveying direction by using a spring 12 as a biasing unit. ing. As a result, even if the thick paper is transported, the convex member 9 is retracted in the direction of the guide surface 13 of the transport guide member 8, so that it is possible to prevent a transport failure. In addition, as a biasing means for imparting elasticity, not only a spring but also a damper member or a resin member having elasticity may be used.

<Embodiment 6>
The convex member 9 can also be configured to be rotatable as shown in FIG. In the figure, the arrow described above the convex member 9 indicates the rotation direction of the convex member 9. In this embodiment, the lower end of the convex member 9 is provided with a support member 9d that supports the convex member 9 so as to be rotatable in the sheet conveying direction. Then, by projecting and biasing the convex member 9 upward of the transport guide member 8 by the spring 12, the convex member 9 is rotationally biased upstream in the sheet transport direction. As the urging means, not only a spring but also a damper member or an elastic resin member can be used.

<Embodiment 7>
FIG. 9 shows an embodiment in which the position of the convex member 9 can be adjusted by adjustment by the user. By adopting this configuration, it is possible to increase the width corresponding to the paper type.

  That is, the convex member 9 in the embodiment of FIG. 7 is always urged with respect to the conveyance guide member 8, but in the embodiment shown in FIG. 9, the movable moving member 17 is urged by the spring 12. . In addition, a lever member 18 that interlocks with the moving member 17 is provided. The moving member 17 is retained by the claw portion 9c.

  In this embodiment, adjustment can be made so that it is possible to cope with a paper type that cannot cope with a conveyance failure only by retracting (lowering) the convex member 9 by the urging force of the spring 12. In this embodiment as well, the position of the convex member 9 can be adjusted not only by manual switching by the user, but also by an automatic switching mechanism using a solenoid or the like corresponding to the print instruction information.

<Operation common to each embodiment>
As described above, according to each embodiment, it is possible to suppress the vibration of the sheet material generated by the friction member 4 and reduce the generation of abnormal noise and noise. Further, the set value of the separation pressure, which is a pressing force for pressing the friction member 4 against the feeding roller 1, and the sheet feeding pressure, which is the pressing force for pressing the sheet material 7 stacked on the sheet stacking plate 2 against the feeding roller 1 are increased. However, abnormal noise and noise are less likely to occur. For this reason, the set value can be freely set, and the sheet feeding performance can be stabilized. That is, by applying contact pressure to the sheet, it is possible to reduce vibrations when the friction member 4 rubs the sheet, and to suppress generation of noise and noise.

  Further, in the embodiment having a configuration in which the convex member 9 can be replaced, it is possible to reduce the transport load applied to the paper against deterioration during durability. Depending on the type of the sheet material, the position of the convex portion can be switched, and the conveyance load on the paper can be reduced. Furthermore, the convex shape can be retracted during transport of thick paper, and the transport load on the paper can be reduced. If the convex members 9 are arranged symmetrically in the width direction of the sheet material, skewing of thick paper or the like can be prevented.

  The present invention is not limited to the embodiments described above, and many variations are possible by those having ordinary knowledge in the art within the technical idea of the present invention.

1: Feed roller 2: Sheet stacking plate 3: Sheet stacking plate pressurizing spring 4: Friction member 5: Holding member 6: Friction member pressurizing spring 7: Sheet material 8: Conveying guide member 8a: Guide groove 8b: Projection 9: Convex-shaped member 9a: Stopper portion 9b: Protruding portion 9c: Claw portion 9d: Support member 10: Feeding nip 12: Convex-shaped pressurizing member 13: Guide surface 14 of guide member: Feed roller shaft 15: Idling roller 16: Rotating shaft 17 of convex member 17: Moving member 18: Lever member 100 for position adjustment: Copier 110: Automatic document feeder 120: Document reading unit 130: Paper feeding unit 140: Image forming unit 150: Paper feeding Cassette 160: Sheet separating and feeding device 170: Conveying path 190: Transfer roller 200: Fixing device 220: Paper discharge tray 230: Image forming unit 240: Intermediate transfer belt 250: Exposure device 2 60: Photoconductor 270: Charging unit 280: Development unit 290: Cleaning unit

JP 2004-189350 A Japanese Patent No. 3744706 JP-A-9-71336

Claims (5)

In a sheet feeding apparatus having a feeding means for feeding a sheet material separated into one sheet from a sheet stacking plate capable of stacking a plurality of sheet materials,
A conveyance guide member that guides sheet material feeding under the feeding unit;
A convex member having a convex shape is arranged at a position deviated from the feeding means of the conveyance guide member,
The upper end of the convex-shaped member, in the pressure-contact portion between the sheet material and said feeding means being fed, Ri sheet material which is fed the supply the name and is positioned above the tangent to the feeding means,
The conveyance guide member is provided with an opening that allows the convex member to move in the width direction of the sheet material orthogonal to the conveyance direction of the sheet material.
A sheet conveying apparatus. The upper end of the convex member is composed of an inclined surface on the upstream side in the conveyance direction of the sheet material,
An angle formed between the tangent line of the sheet material and the feeding unit and the inclined surface is 45 degrees or less,
The sheet conveying apparatus according to claim 1.   The sheet conveying apparatus according to claim 1, wherein an upper end of the convex member includes a portion formed of a curved surface. The convex member is provided at its upper end with a rotating body that can rotate in the conveying direction of the sheet material.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. An image forming apparatus comprising: the sheet conveying apparatus according to claim 1; and an image forming unit that forms an image according to image information .