JP4881587B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus for supplying a document or a recording sheet to a copying machine, a facsimile, a printer, or the like, and an image forming apparatus using the sheet feeding apparatus.

  2. Description of the Related Art In recent years, attention has been paid to the problem of reduction in operation noise as well as stability of sheet feeding performance in a sheet feeding apparatus mounted on an image forming apparatus such as a copying machine or a printer.

  A sheet feeding apparatus used in a copying machine, a printer, or the like separates and feeds stacked sheets one by one. Conventionally, in this sheet feeding apparatus, there is a system in which sheets are separated one by one by a feeding roller that feeds the sheet and a separation pad that is biased against the feeding roller and prevents double feeding of the sheet. In this sheet separation method, stick slip (minute vibration) may occur between the sheet and the separation pad depending on the type of sheet to be fed, and abnormal noise may be generated due to the vibration. Therefore, in order to prevent the generation of this abnormal noise, a method for preventing the generation of abnormal noise by providing a vibration damping member on the separation pad and preventing the vibration of the separation pad has been proposed (for example, Patent Document 1). reference).

JP-A-8-091608

  However, in the above conventional example, although the effect of suppressing the vibration of the separation pad can be obtained, the sheet itself as the vibration source cannot be sufficiently prevented from vibration, and the effect of suppressing the vibration depending on the configuration of the sheet feeding device. Could not be obtained. Further, there is a risk that vibrations are amplified and a larger noise is generated.

  In order to suppress the vibration of the sheet, it is conceivable to adjust the contact pressure between the feeding roller and the separation pad. However, if the contact pressure is set small, sufficient sheet feeding performance can be obtained. Cause non-feeding of the sheet. On the other hand, if the contact pressure is set large, the possibility of stick-slip between the sheet and the separation pad increases, and the possibility of abnormal noise generation increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a sheet feeding apparatus capable of suppressing the generation of abnormal noise during sheet feeding without deteriorating the sheet feeding performance, and an image including the same. A forming apparatus is provided.

The present invention for solving the above-described problems is a feeding device that is fixed to a rotating shaft, has a notch portion on the outer periphery, and the outer periphery slides on the upper surface of the stacked sheets to apply a feeding force to the sheets. A roller, a pad member that is in pressure contact with the feeding roller and separates the sheet from the feeding roller, and is rotatably provided on the rotating shaft, and is smaller than an outer diameter of the feeding roller and the A roller portion that protrudes outward from the notch portion, and that can contact the pad member when the notch portion faces the pad member, and a sheet that is sandwiched between the pad member and the roller portion And a vibration damping member for suppressing vibration of the roller portion that is generated when being fed, and the vibration damping member is formed of a vibration-proof rubber sheet, and the vibration damping member is disposed on a side surface of the roller portion. It is characterized by being attached to.

Further, the present invention provides a feeding roller that is fixed to the rotating shaft, has a notch portion on the outer periphery, and the outer periphery slides on the upper surface of the stacked sheets to apply a feeding force to the sheet, A pad member that is in pressure contact with the feed roller and separates the sheet from the feed roller; and is rotatably provided on the rotating shaft, and is smaller than the outer diameter of the feed roller and smaller than the notch in shape protruding outwardly, wherein the said pad member and capable of abutting roller unit when the notch is opposed to the pad member, the sheet is fed is held between the pad member and the roller unit and vibration damping member for suppressing vibration of the roller unit at occurring that, wherein the damping member is a metal piece for increasing the total weight of the roller portion, the metal strip the roller unit It is attached to the side of

  According to the present invention, when the sheet fed by the feeding roller is conveyed downstream, the roller portion comes into contact with the sheet to suppress stick slip between the sheet and the pad member, thereby suppressing the vibration of the sheet. The occurrence of abnormal noise can be suppressed.

  Next, a sheet feeding apparatus according to an embodiment of the present invention will be described with reference to the drawings together with an image forming apparatus using the sheet feeding apparatus.

[First Embodiment]
A sheet feeding apparatus and an image forming apparatus including the sheet feeding apparatus according to the first embodiment will be described with reference to FIGS. 1 to 6.

{Overall configuration of image forming apparatus}
First, an overall configuration of an image forming apparatus using a sheet feeding apparatus will be schematically described with reference to FIG.

  As shown in FIG. 6, a sheet feeding apparatus A is provided at the lower part of the image forming apparatus main body. The configuration of the sheet feeding apparatus A will be described in detail later. The sheet S fed from the sheet feeding apparatus A is conveyed to the image forming unit by the conveying roller pair 11 and the registration roller pair 12. The image forming unit in the present embodiment forms an image by electrophotography, and a charging unit and a developing unit (not shown) are arranged around the electrophotographic photosensitive drum 13. Then, a toner image is formed on the photosensitive drum 13 in synchronization with the sheet conveyance, and the toner image is transferred to the conveyed sheet S by applying a transfer bias to the transfer roller 14.

  The sheet S on which the toner image has been transferred is conveyed to the fixing device 16 by the conveying belt 15, and after being thermally fixed, is discharged to a discharge portion 19 at the upper part of the apparatus main body by a pair of discharge rollers 17 and 18.

{Sheet feeding device}
Next, the sheet feeding apparatus A will be described. 1 and 2 are schematic configuration explanatory views of an example of a sheet feeding apparatus according to the first embodiment.

  A middle plate 101 is provided in a feeding cassette (not shown) and pushes up the sheets stacked on the upper surface upward. Reference numeral 102 denotes a feeding roller on which the leading edge of the uppermost sheet in the sheet pushed up by the intermediate plate 101 comes into contact. The feeding roller 102 includes a core 102a, a roller portion 102b attached to the core 102a, and a roller holder 102c to which the core 102a fixed to the rotating shaft 108 and attached with the roller portion 102b is attached.

  Rollers 109 are arranged on both sides of the feed roller 102 and are provided so as to be rotatable with respect to the rotating shaft 108 or the roller holder 102c.

  In FIGS. 1 and 2, reference numeral 103 denotes a separation pad holding member provided below the feeding roller 102, and 104 denotes a lower side of the feeding roller 102 provided above the separation pad holding member 103. It is a separation pad as a pad member which contacts. Reference numeral 105 denotes a spring that biases the separation pad holding member 103 toward the feeding roller 102.

  The separation pad holding member 103 is configured to be rotatable within a predetermined range by a hinge member (not shown).

  When the feeding roller 102 rotates, the roller portion 102b of the feeding roller 102 contacts and feeds the uppermost sheet of the stacked sheets. When a plurality of sheets are sent out, the sheets are separated one by one between the separation pad 104 and the feeding roller 102. The separated sheet is conveyed to the image forming unit by the conveyance roller pair 11 while being guided by the conveyance guide 106.

  Here, when the outer peripheral radii of the roller holder 102c, the roller portion 109, and the roller portion 102b are Ra, Rb, and Rc, respectively, the radius Rb of the outer peripheral surface of the roller portion 109 is larger than the outer peripheral radius Ra of the roller holder 102c. The radius Rc of the outer peripheral surface of the roller portion 102b attached to the core 102a is larger than the radius Rb of the outer peripheral surface of the roller portion (Ra <Rb <Rc). Therefore, when the roller unit 109 is attached to the rotary shaft 108 or the roller holder 102c, the outer peripheral surface of the roller unit 109 is positioned on the inner side of the outer peripheral surface of the roller unit 102b and positioned on the outer side of the outer periphery of the roller holder 102c. To do. With this configuration, the feeding roller 102 has a structure in which a cutout portion is formed on the outer periphery (a so-called half-moon shaped roller).

  FIG. 3 is an explanatory diagram showing a standby state before sheet separation and conveyance of the sheet feeding apparatus in the present embodiment. The sheet placed on the intermediate plate 101 is in contact with the two roller portions 109 when the intermediate plate 101 is lifted upward by the biasing spring 301. Further, the separation pad 104 is in contact with the two roller portions 109 by the bias of the spring 105. For this reason, the positions of the feeding roller 102 and the separation pad 104 in the standby state are determined by the roller unit 109.

  Then, by rotating the feeding roller 102, the outer peripheral surface of the feeding roller 102 comes into contact with the uppermost sheet to apply a feeding force, and the uppermost sheet is fed out. The fed sheet passes through the nip portion between the roller 109 and the separation pad 104 and is conveyed to the conveying roller pair 11. The feed roller 102 rotates once by a clutch mechanism (not shown), and stops so that the position where the outer peripheral surface of the feed roller 102 is cut away faces the separation pad 104 as shown in FIG.

  At this time, since the conveying roller pair 11 continues to rotate, the sheet passing between the roller portion 109 and the separation pad 104 is conveyed by the conveying roller pair 11 as it is. Since the roller unit 109 is rotatably attached to the rotating shaft 108 or the roller holder 102c, the roller unit 109 is rotated along with the conveyance of the sheet. In this way, the roller unit 109 rotates and the sheet is conveyed while being in contact with the separation pad 104, thereby preventing double feeding of the sheet with a small back tension against the conveying force.

{Rolling part vibration suppression means}
The sheet feeding apparatus A of the present embodiment is provided with vibration suppressing means for suppressing vibration of the roller unit 109 during sheet conveyance. Next, the configuration of the vibration suppressing means will be described.

  FIG. 4 is an enlarged explanatory view of the sheet feeding unit during sheet conveyance. In the sheet feeding apparatus A described above, the sheet fed by the feeding path roller 102 is conveyed while being sandwiched between the separation pad 104 and the roller unit 109. This clamping force is determined by the elastic force (200 (gf) in this embodiment) of the spring 105 that urges the separation pad holding member.

  While the sheet is conveyed by the conveying roller pair 11, stick slip may occur due to the rubbing between the sheet and the separation pad 104 depending on the type of the sheet. This stick-slip causes an abnormal sound called “pad noise”.

  For the occurrence of stick-slip in the sheet feeding unit, the elastic force of the spring 105 that presses the separation pad 104, the sheet conveyance speed, the sheet type / rigidity, the friction coefficient of the separation pad 104, the rigidity of each component of the feeding unit, etc. Is due. These factors are closely related to the feeding performance of the sheet feeding apparatus, and it has been difficult to achieve both noise countermeasures.

  Therefore, in this embodiment, in order to take measures against abnormal noise without impairing the sheet feeding performance, vibration of the roller unit 109 is suppressed and abnormal noise is prevented.

  That is, in FIG. 4A, when the vibration suppressing means is not provided in the roller portion 109, the roller portion 109 also vibrates in accordance with the vibration transmitted from the sheet, and it is difficult to suppress the vibration of the sheet due to stick slip. .

  On the other hand, in this embodiment, as shown in FIG. 4B, a damping member 201 having damping properties such as a rubber member or a resin member is attached to the side surface of the roller portion 109. In this embodiment, a polyacetal resin (POM) material is used as the roller portion 109, and a vibration-proof rubber sheet is used as the vibration damping member 201. As the damping member 201, a material necessary and sufficient to suppress vibration is selected by a combination of the elastic force 200gf of the spring 105 that urges the separation pad and the conveyance speed 50 (mm / s).

  As described above, by providing the damping member 201 on the side surface of the roller portion 109, the vibration of the sheet is suppressed. Furthermore, the vibration of the roller portion 109 due to the vibration transmitted from the sheet is also suppressed. For this reason, the occurrence of continuous vibration such as stick-slip during sheet feeding is prevented, and the generation of abnormal noise can be suppressed.

  FIG. 5A shows a conventional sheet feeding apparatus that does not include the vibration suppressing means of the roller unit 109. When abnormal noise occurs, the sheet is conveyed on the separation pad 104 and between the two roller units 109. It is a graph which shows the result of having measured the time displacement of the sheet | seat. On the other hand, FIG. 5B is a graph showing a result of measuring the time displacement of the sheet during sheet conveyance in the sheet feeding apparatus in which the damping member 201 in this embodiment is attached to the roller unit 109.

  From FIG. 5A, it can be seen that when abnormal noise is generated, the seat is vibrated by stick-slip. On the other hand, as shown in FIG. 5B, it can be seen that the vibration of the seat is suppressed by attaching the damping member 201 to the roller portion 109.

  In this way, the vibration damping member 201 is bonded to the side surface of the roller portion 109, or the vibration member 201 is sandwiched by the vibration damping member 201 so as to attenuate the vibration generated in the sheet and prevent the generation of abnormal noise. can do.

  Further, by attaching a weight to the roller portion 109, or increasing the diameter or increasing the weight or specific gravity of the roller portion 109, the roller portion 109 is prevented from vibrating and the resonance point is increased to cause the roller portion 109 to vibrate. You may make it difficult.

[ Second Embodiment]
Next, apparatus according to a second embodiment will be described with reference to FIGS. 4 and 7. The basic configuration of the apparatus according to the present embodiment is also the same as that of the first embodiment described above, and a duplicate description thereof will be omitted. Here, a configuration that is a feature of the present embodiment will be described. Moreover, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above.

  This embodiment is different from the above-described embodiment in that the total weight of the roller portion 109 is set so as to suppress the vibration of the seat.

  In the present embodiment, a metal piece is attached as the damping member 201 as a configuration for setting the total weight of the roller portion 109. This is because POM material is used as the roller portion 109, and a metal piece 201 having a thickness of 1 mm is attached thereto, so that the total weight of the roller portion 109 and the damping member (metal piece) 201 is 5 ( g).

  For the metal piece 201, a material that is necessary and sufficient to suppress vibration is selected by a combination of the elastic force 200 (gf) of the spring 105 that urges the separation pad 104 and the sheet conveyance speed 50 (mm / s). In order to enhance the damping effect, the metal piece 201 can be made heavy, that is, the thickness of the metal piece can be increased. However, in order to increase the cost, in this embodiment, a metal piece having a thickness of 1 (mm) is used. A plurality of metal pieces can be attached according to the set weight.

FIG. 7 shows an experiment of the relationship between the total weight of the roller portions 109 to which the damping members 201 are attached, which is necessary for preventing pad noise at the conveyance speed when the conveyance speed in the sheet feeding apparatus of the present embodiment is changed. It is the graph calculated | required. As can be seen from this graph, it is necessary to increase the total weight of the roller portion 109 in order to suppress abnormal noise when the sheet conveyance speed is low than when the sheet conveyance speed is low.

  From the above results, it is assumed that the sheet conveyance speed is X (mm / s), and the total weight Y of the roller portion 109 to which the vibration damping member 201 is attached is (g). At this time, the reference for setting the total weight of the roller portion 109 to which the damping member 201 for suppressing the vibration of the roller portion 109 to suppress the generation of abnormal noise is as follows.

Y ≧ 4.5 × 10 ⁻² X + 2.5
Also, depending on the sheet feeding apparatus, it is conceivable to increase the elastic force of the spring 105 in order to improve the sheet separation performance. In such a case, the vibration of the sheet due to stick-slip becomes a high-frequency vibration. In order to suppress this vibration, it is possible to shift the resonance point and suppress the vibration by increasing the total weight of the roller portion 109.

FIG. 3 is a cross-sectional configuration explanatory diagram of a sheet feeding device according to the first embodiment. FIG. 3 is an explanatory perspective view of a sheet feeding device according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a standby state before sheet separation and conveyance in the sheet feeding device according to the first embodiment. 4A and 4B are enlarged explanatory views of a sheet feeding unit during sheet conveyance, in which FIG. 5A shows an example in which a vibration damping member is not provided, and FIG. It is a graph which shows the result of having measured the time displacement of the sheet between the roller parts during sheet conveyance, (a) shows the case where a damping member is not provided, and (b) shows the case where a damping member is provided. 1 is a schematic cross-sectional explanatory diagram of an image forming apparatus. It is the graph which experimented and calculated | required the relationship between the roller part required in order to prevent pad squealing in the sheet | seat conveyance speed which concerns on 2nd Embodiment, and the damping member.

A ... sheet feeding device S ... sheet 11 ... conveying roller pair 12 ... registration roller pair 13 ... photosensitive drum 14 ... transfer roller 15 ... conveying belt 16 ... fixing device 17, 18 ... discharge roller pair 19 ... discharge unit 101 ... medium Plate 102 ... Feed roller 102a ... Core 102b ... Roller part 102c ... Roller holder 103 ... Separation pad holding member 104 ... Separation pad 105 ... Spring 106 ... Conveyance guide 107 ... Conveyance roller 108 ... Rotating shaft 109 ... Roller part 201 ... Damping Member 301 ... biasing spring

Claims (5)

A feeding roller fixed to the rotating shaft, provided with a notch on the outer periphery, and the outer periphery is in sliding contact with the upper surface of the stacked sheets to apply a feeding force to the sheet;
A pad member that is in pressure contact with the feeding roller and separates the sheet from the feeding roller;
The rotary shaft is rotatably provided, has a shape that is smaller than the outer diameter of the feeding roller and protrudes outward from the notch, and the notch is opposed to the pad member. A roller that can contact the pad member;
A damping member for suppressing vibration of the roller portion that occurs when the sheet is nipped and fed between the pad member and the roller portion,
The vibration damping member is formed of a vibration-proof rubber sheet, and the vibration damping member is attached to a side surface of the roller portion. A feeding roller fixed to the rotating shaft, provided with a notch on the outer periphery, and the outer periphery is in sliding contact with the upper surface of the stacked sheets to apply a feeding force to the sheet;
A pad member that is in pressure contact with the feeding roller and separates the sheet from the feeding roller; and is rotatably provided on the rotating shaft and is smaller than an outer diameter of the feeding roller and the notch A roller portion that protrudes outwardly and is capable of contacting the pad member when the notch portion faces the pad member;
A damping member for suppressing vibration of the roller portion that occurs when the sheet is nipped and fed between the pad member and the roller portion,
The vibration damping member is a metal piece for increasing the total weight of the roller portion, and the metal piece is attached to a side surface of the roller portion. When the sheet feeding speed by the feeding roller is X (mm / s) and the total weight of the roller portion is Y (g), the relationship is Y ≧ 4.5 × 10 ⁻² X + 2.5. The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus.   The sheet feeding apparatus according to claim 2, wherein a plurality of the metal pieces are attached. In an image forming apparatus that feeds a sheet and forms an image on the sheet,
The sheet feeding apparatus according to any one of claims 1 to 4,
Image forming means for forming an image on a sheet fed from the sheet feeding device;
An image forming apparatus comprising:

Images