JP4143460B2 - Sheet conveying apparatus and image processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus using a conveying roller that contacts a sheet and conveys the sheet by its frictional force, or a separating pad for separating the sheet, and an image of an electrophotographic copying machine, a printer, a word processor, a facsimile apparatus, and the like. The present invention relates to a processing apparatus.
[0002]
[Prior art]
2. Description of the Related Art In recent years, image forming apparatuses such as printers and copiers that employ an electrophotographic system and other recording systems have become widespread. As the performance of the apparatus increases and the life of the apparatus increases, it is necessary to improve the feeding accuracy and durability of the conveyance roller used in the image forming apparatus. Similarly, separation pads used in image forming apparatuses need to be improved in separation accuracy and durability.
[0003]
Here, as shown in FIG. 9, the conventional conveying roller 100 includes a shaft portion 101 which is a metal or a mold, and a rubber material such as EPDM (ethylene / propylene rubber), CR rubber (chloroprene rubber), silicon rubber, urethane rubber or the like. 9 is formed of a cylindrical rubber portion 102 that contacts the recording sheet and conveys the recording sheet by frictional force. The cylindrical surface 102a of the cylindrical rubber portion 102 has a direction indicated by an arrow C or D in FIG. Polished.
[0004]
10 is also formed of a rubber material such as EPDM, CR rubber, silicon rubber, urethane rubber, and the like, as in the case of the conveyance roller 100 described above, and a rubber portion 104 that contacts the conveyance roller, and a rubber portion 104. It is comprised from the holder 105 which hold | maintains. The rubber surface 104a of the rubber part 104 is polished in the direction of arrow E or F shown in FIG.
[0005]
[Problems to be solved by the invention]
However, the conventional conveying roller and separation pad have the following problems.
[0006]
When a recording sheet is conveyed by a conventional conveying roller, paper dust generated from the surface of the recording sheet adheres to the cylindrical surface of the conveying roller as the number of conveyed recording sheets increases, and the frictional force of the conveying roller decreases. As a result, there is a problem that the recording sheet is slipped and an image defect or a jam occurs. For this reason, in order to extend the product life of the apparatus main body, a configuration in which the user is requested to clean the transport roller or the user can replace the transport roller is employed. As a result, the usability is reduced, and the cost is increased due to the addition of parts with a configuration in which the transport roller can be replaced.
[0007]
Also, when recording sheets are separated and transported with a conventional separation pad, as the number of recording sheets separated and transported increases, paper dust generated from the surface of the recording sheet adheres to the surface of the separation pad, and the frictional force of the separation pad There is a problem that the recording sheet is double fed. Therefore, the same problem as in the case of the transport roller has occurred.
[0008]
The present invention solves the above-mentioned conventional problems, and its purpose is to prevent a decrease in friction force due to paper dust adhesion and a decrease in friction force due to wear, to realize a highly durable roller member, etc., and to achieve a long service life and maintenance. A sheet conveying apparatus and an image forming apparatus using a free and inexpensive conveying roller or a separation pad are provided.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a typical configuration according to the present invention is a sheet conveying apparatus having a conveying roller that contacts a sheet and rotates to convey the sheet , and a plurality of the conveying rollers are provided on a working surface with the sheet. A surface layer having a protrusion and an intermediate layer provided between the surface layer and the support portion, and the protrusion on the surface layer is provided with a spherical portion at the tip of the standing portion rising from the surface of the surface layer. and an elastic deformable structure, characterized in that the hardness of the intermediate layer is set lower than the hardness of the surface layer.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an image forming apparatus that forms an image on a sheet will be described as an example of an image processing apparatus using a sheet action member according to an embodiment of the present invention.
[0011]
[First Embodiment]
The first embodiment will be described with reference to FIGS. 1 to 6 which show an example in which a sheet action member is used as a conveyance roller. 1 is an enlarged explanatory view showing the nip state of the conveying roller, FIG. 2 is an overall schematic explanatory view of the image forming apparatus, and FIG. 3 is a perspective explanatory view showing the entire conveying roller, FIGS. These are explanatory drawings of minute protrusions formed on the roller surface.
[0012]
{Image processing device}
First, the overall configuration of the image forming apparatus will be described with reference to FIG. In FIG. 2, the image forming apparatus A separates and conveys the recording sheets P stacked by the sheet conveying apparatus B one by one, and the recording sheets P are conveyed to the image forming unit by a conveying roller pair 1 including a conveying roller 1a and a conveying roller 1b. The image is recorded by an electrophotographic method. That is, the photosensitive drum 3 accommodated in the process cartridge 2 is rotated in synchronization with the recording sheet conveyance, and the surface of the photosensitive drum 3 is charged by the primary charger 4 and then selectively selected from the laser scanning optical system 5. An electrostatic latent image is formed by irradiating light with light, and the latent image is developed with toner by the developing device 6. The toner image is transferred to the recording sheet P by applying a transfer bias to the transfer roller 7 with respect to the conveyed recording sheet P.
[0013]
Next, the recording sheet P to which the toner image has been transferred is heated and pressed by the fixing device 8 to fix the toner image on the recording sheet P. The recording sheet P after fixing is a pair of discharge rollers comprising a discharge roller 9a and a discharge roller 9b. 9 is configured to discharge to the discharge tray 10.
[0014]
{Sheet conveying device}
The sheet conveying apparatus B includes a feeding tray 11 that supports the recording sheet P, and a pressure plate 13 that is a pressing unit for pressing the leading end side of the recording sheet P supported by the feeding tray 11 against the conveying roller 12. , A pressure spring 14 for urging the pressure plate 13, a separation pad 15 that is a separation means for separating the recording sheets P sent out by the conveyance roller 12 one by one, and a separation pad 15 attached to the conveyance roller 12 And a separating spring 16 to be energized.
[0015]
The cam 17 is fixed to the shaft 18 of the conveying roller 12 and is in contact with the cam portion 13a of the pressure plate 13 so that the recording material P is not in contact with the conveying roller 12 in the apparatus standby state. Is energized.
[0016]
The transport roller 12 feeds the recording sheet P separated into one sheet by the separation pad 15 to the transport path 19 while contacting the uppermost sheet surface of the plurality of recording sheets P stacked and supported on the feeding tray 11. To be sent.
[0017]
{Sheet acting member}
Next, the configuration of the conveying roller 12 used in the sheet conveying apparatus B will be described with reference to FIGS.
[0018]
The conveying roller 12 is a sheet action member that imparts a conveying force to the sheet by a frictional force. As shown in FIG. 3, the shaft portion 20 as a supporting portion whose material is a metal or a mold, and the outermost periphery of the conveying roller 12 A cylindrical surface layer rubber portion 22 which is a surface layer and made of a rubber material such as EPDM, CR rubber, silicon rubber, urethane rubber, etc., contacts the recording sheet P, and conveys the recording sheet P by friction force; An intermediate layer provided between the outer periphery of the shaft portion 20 and the surface rubber portion 22, and the intermediate layer rubber portion 23 made of a rubber material such as EPDM, CR rubber, silicon rubber, urethane rubber, etc. Composed.
[0019]
As shown in FIGS. 4 and 5, minute protrusions 24 are formed on the cylindrical surface 22 a of the cylindrical surface rubber portion 22 of the conveying roller 12 by fine processing.
[0020]
(Micro projections)
As shown in FIG. 4, the minute protrusion 24 has a shape constituted by an upright portion 24a standing up from the cylindrical surface 22a and a spherical spherical portion 24b at the tip of the upright portion 24a. The minute protrusions 24 are arranged so as to be at substantially equal intervals L with the adjacent minute protrusions 24. Further, the height of the minute protrusions 24 is formed in the range of 1 μm to 500 μm in consideration of the size and thickness of the recording sheet P to be conveyed.
[0021]
This is because if it is lower than 1 μm, the effect of preventing paper dust from adhering to the conveying roller 12 is small and the improvement in durability is small. It is desirable that the height of the minute protrusions 24 be in the above range because the influence of the force on the conveying force increases and it becomes difficult to maintain a stable conveying force.
[0022]
In the present embodiment, the upright portion 24a of the minute protrusion 24 has a cylindrical shape. Further, as shown in FIG. 5, the diameter R of the spherical portion 24b is configured to be larger than the cylindrical diameter (thickness) r of the standing portion 24a and smaller than the length h of the standing portion 24a.
[0023]
When the recording sheet P is conveyed by the conveying roller 12 provided with the minute protrusions 24 in the above configuration, the conveying roller 12 rotates in the direction of arrow A as shown in FIG. Conveyed in the direction. At this time, the recording sheet P is conveyed by a frictional force generated in contact with the spherical portion 24b of the conveying roller. Then, as shown in FIG. 6 (a), the ridges 24a of the minute protrusions 24 that are in contact with the recording sheet P are elastically deformed in a direction opposite to the recording sheet P conveyance direction (arrow A direction). It is in a fallen state. In this state, the recording sheet P is transported. While the recording sheet P is being transported, a minute fallen object (hereinafter simply referred to as “paper dust”) from the surface of the recording sheet P at the contact portion between the recording sheet P and the spherical portion 24b. S) occurs and increases near the contact portion.
[0024]
Then, when the conveyance of the recording sheet P is finished, the minute protrusions 24 are released from the elastically deformed state and returned to the molded state as shown in FIG. 6 (b). At this time, the paper dust S generated at the contact portion between the spherical portion 24b and the recording sheet P is deposited on the cylindrical surface 22a without adhering to the spherical portion 24b because the spherical portion 24b is minute.
[0025]
Here, when the recording sheet P is transported by the transport roller 12, as the number of transports of the recording sheet P increases, there is a possibility that the minute protrusions 24 of the transport roller 12 in contact with the recording sheet are worn and deformed or lost. There is a possibility that the frictional force of the conveying roller 12 is lowered and slippage occurs in the conveyance of the recording sheet.
[0026]
For this reason, if the hardness of the rubber material of the transport roller 12 is increased in order to increase the wear resistance of the microprojections 24, the wear resistance can be improved, but the nip width between the separation pad 15 contacting the transport roller 12 is small. As a result, the contact surface with the recording sheet to be conveyed is reduced, and as a result, conveyance failure may occur.
[0027]
On the other hand, if the pressing force of the separation pad 15 is increased in order to increase the nip width between the separation pad 15 and the conveying roller 12, the torque load of the product increases.
[0028]
Therefore, in the present embodiment, the above problem is improved by making the hardness of the roller different between the surface layer and the intermediate layer below it.
[0029]
(Hardness of elastic layer)
Next, the hardness of the conveying roller 12 will be described. The intermediate layer rubber part 23 of the conveying roller 12 shown in FIGS. 1 and 3 is made of foamed sponge rubber (foamed layer) having pores or a rubber material having a low hardness of about 15 ° to 30 °, for example. For example, a rubber material having a high hardness of 40 ° or more and excellent wear resistance is used for the surface rubber portion 22, and the hardness of the intermediate rubber portion 23 is set lower than the hardness of the surface rubber portion 22. .
[0030]
In FIG. 1, N is a nip between the conveying roller 12 and the separation pad 15. In the conveyance roller 12 of the present embodiment, even when a rubber material having high hardness and excellent wear resistance is used for the surface rubber portion 22, the surface hardness of the conveyance roller is reduced by setting the hardness of the intermediate rubber portion 23 low. Therefore, the width of the nip N between the conveying roller 12 and the separation pad 15 can be increased in a state where the pressing force of the separation pad 15 is low.
[0031]
As a result, the conveyance roller 12 having excellent wear resistance can be realized, and the feeding / conveying performance can be improved even when the pressing force of the separation pad 15 is low, and the sheet conveying device B is reduced by reducing the pressing force of the separation pad 15. There is also an effect that the driving torque can be lowered.
[0032]
Of course, even if the conveying roller 12 has a D-shaped cross section, the same effect can be obtained. Further, in the present embodiment, the intermediate rubber portion 23 of the transport roller 12 is a single layer, but even if a plurality of elastic layers are used, a rubber material having a lower hardness than the surface rubber portion 22 is used. Has the same effect.
[0033]
[Second Embodiment]
As a second embodiment of the present invention, an example in which a sheet action member is used for the separation pad 15 will be described with reference to FIGS. FIG. 7 is a schematic perspective explanatory view showing the entire separation pad, and FIG. 8 is an enlarged perspective explanatory view of a portion where a minute protrusion provided on the separation pad is present.
[0034]
As shown in FIG. 7, the separation pad 15 according to the present embodiment is formed of a holder portion 25 as a support portion made of a metal or a mold, and a rubber material such as EPDM, silicon rubber, or urethane rubber. A high friction surface rubber portion 26 that contacts the recording sheet P and separates the recording sheet P by frictional force, and an intermediate layer provided between the holder portion 25 and the high friction surface rubber portion 26, Is formed of an intermediate layer rubber portion 23 formed of a rubber material such as EPDM, CR rubber, silicon rubber, urethane rubber or the like.
[0035]
The high friction surface rubber portion 26, which is the surface layer, is provided with the minute protrusions 24 similar to those in the first embodiment.
[0036]
Further, as in the first embodiment, the intermediate rubber portion 23 of the separation pad 15 is made of foamed sponge rubber having pores or a low hardness rubber material having a hardness of about 15 ° to 30 °, for example. The high friction surface rubber part 26 is made of a rubber material having a hardness of 40 ° or higher and excellent wear resistance. The hardness of the intermediate layer rubber part 23 is set lower than the hardness of the high friction surface rubber part 26. Has been.
[0037]
Therefore, even when a rubber material having high hardness and excellent wear resistance is used for the high friction surface rubber part 26, the separation pad surface hardness can be lowered by setting the hardness of the intermediate layer rubber part 23 low. When the sheet is separated by the separation pad 15, as shown in FIG. 5, the width of the nip N between the separation pad 15 and the conveying roller 12 can be increased while the pressing force of the separation pad 15 is low.
[0038]
As a result, the separation pad 15 having excellent wear resistance can be realized, and the separation performance can be improved even when the pressing force of the separation pad 15 is low, and the sheet conveying apparatus B is driven by reducing the pressing force of the separation pad 15. There is also an effect that torque can be lowered.
[0039]
[Other Embodiments]
In the embodiment described above, an example in which the upright portion 22a of the microprojection 22 is cylindrical is shown, but the shape of the upright portion 22a is not limited to a cylindrical shape, and may be conical, polygonal, or polygonal.
[0040]
In the first embodiment described above, the conveyance roller 12 is described as the sheet action member. However, the conveyance roller 12 is configured in the same manner with respect to the other conveyance rollers 1a, the transfer roller 7, and the discharge roller 9a. A similar effect can be obtained.
[0041]
In the above-described embodiment, an image forming apparatus that conveys a sheet as an image processing apparatus and records an image on the sheet is exemplified. However, a plurality of conveyance rollers, separation pads, or sheet conveyance apparatuses as the above-described sheet action member may be used. Can be suitably used also in an image reading apparatus that separates and conveys the original document one by one and reads it by an image reading means.
[0042]
【The invention's effect】
As described above, according to the present invention, the wear resistance of the plurality of elastically deformable protrusions having a spherical portion at the tip of the standing portion provided on the conveying roller or the separation pad is improved, and at the same time, the pressing against the sheet action member is performed. Since the nip width can be ensured even if the pressure is reduced, a highly durable sheet action member can be realized, and a sheet conveying apparatus having a long life and low torque can be realized.
[Brief description of the drawings]
FIG. 1 is an enlarged explanatory view showing a nip state of a conveying roller.
FIG. 2 is an overall schematic explanatory diagram of an image forming apparatus.
FIG. 3 is an explanatory perspective view illustrating the entire conveyance roller.
FIG. 4 is an explanatory diagram of minute protrusions formed on a roller surface.
FIG. 5 is an explanatory diagram of minute protrusions formed on a roller surface.
FIG. 6 is an explanatory diagram of minute protrusions formed on a roller surface.
FIG. 7 is a schematic perspective view illustrating the entire separation pad.
FIG. 8 is an enlarged perspective explanatory view of a portion where minute protrusions provided on a separation pad are present.
FIG. 9 is a schematic perspective view of a conventional conveying roller.
FIG. 10 is a schematic perspective view of a conventional separation pad.
[Explanation of symbols]
A ... Image forming apparatus B ... Sheet conveying apparatus P ... Recording sheet S ... Paper dust 1 ... Conveying roller pair 1a ... Conveying roller 1b ... Conveying roller 2 ... Process cartridge 3 ... Photoconductor drum 4 ... Primary charger 5 ... Laser scanning optics System 6 ... Developer 7 ... Transfer roller 8 ... Fixer 9 ... Discharge roller pair 9a ... Discharge roller 9b ... Discharge roller
10… discharge tray
11… Feeding tray
12… Conveying roller
13… Pressure plate
13a ... Cam part
14… Pressure spring
15… Separation pad
16… separation spring
17… Cam
18 axis
19… Conveyance path
20 ... Shaft
22… rubber layer on the surface
22a ... cylindrical surface
23… Middle layer rubber part
24… microprotrusions
24a ... Standing part
24b ... Spherical part
25… Holder part
26… High friction surface rubber part

Claims (7)

In a sheet conveying apparatus having a conveying roller that contacts and rotates and conveys a sheet ,
The transport roller is
A surface layer having a plurality of protrusions on the working surface with the sheet;
An intermediate layer provided between the surface layer and the support;
Have
The protrusion on the surface layer is an elastically deformable structure in which a spherical portion is provided at the tip of an upright portion rising from the surface of the surface layer,
The sheet conveying apparatus according to claim 1, wherein the hardness of the intermediate layer is set lower than the hardness of the surface layer. The sheet conveying apparatus according to claim 1, wherein the intermediate layer is a foam layer having pores. The sheet according to claim 1, wherein the intermediate layer has a plurality of elastic layers, and the hardness of at least one elastic layer of the plurality of elastic layers is lower than the hardness of the surface layer. Conveying device . In a sheet conveying apparatus provided with a separation pad for contacting a sheet to be conveyed and separating a plurality of sheets into one sheet ,
The separation pad is
A surface layer having a plurality of protrusions on the working surface with the sheet;
An intermediate layer provided between the surface layer and the support;
Have
The protrusion of the surface layer has a configuration in which a spherical portion is provided at the tip of an upright portion rising from the surface of the surface layer,
The sheet conveying apparatus according to claim 1, wherein the hardness of the intermediate layer is set lower than the hardness of the surface layer . The sheet conveying apparatus according to claim 4, wherein the intermediate layer is a foam layer having pores . The sheet according to claim 4, wherein the intermediate layer has a plurality of elastic layers, and the hardness of at least one of the plurality of elastic layers is lower than the hardness of the surface layer. Conveying device . Image forming means for forming an image on a sheet or image reading means for reading an image of a sheet document;
The image processing apparatus characterized by having a sheet conveying apparatus according to any one of the said image forming means or claims 1 to claim 6 for feeding sheets to the image reading means.

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