JP2003246479A - Paper feeding device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeding device and an image forming device capable of considerably reducing torque of a drive source during paper feeding operation to thereby remarkably lengthen the service life of the drive source. <P>SOLUTION: A separation roller 22 is supported to a separation shaft 22a through a torque limiter 25. The separation shaft 22a is provided with an intermediate shaft 32 drive-connected by gears 37, 36. A separation one-way clutch 34 allowing the rotation of the separation roller 22 only in a paper return direction is connected to the intermediate shaft 32. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device and an image forming apparatus used in copying machines, printers, facsimiles, printing machines and the like.

[0002]

2. Description of the Related Art In a sheet feeding device used in an image forming apparatus, various separating systems for feeding sheets one by one have been proposed, and a typical example thereof is a friction separating system.
A sheet feeding device that adopts this friction separation (hereinafter, referred to as FRR) system includes a feed roller that rotates in the sheet feeding direction and a torque limiter that is pressed against the feed roller and is rotationally driven in the direction opposite to the sheet feeding direction. It has a separation roller between them, and when one sheet is sandwiched between the rollers, the separation roller is rotated by a torque limiter, and when two or more sheets are sandwiched, the separation roller rotates in the opposite direction to the paper feeding direction. 1 sheet of paper
It is a sheet feeding device that can separate and convey sheets one by one.

In the above-mentioned FRR sheet feeding device, the separation roller is constantly subjected to torque in the direction opposite to the sheet feeding direction of the feed roller. Therefore, even when the drive of the feed roller is turned off by the electromagnetic clutch that continuously disconnects the drive to the feed roller, the separation roller is always driven in the reverse direction, so that the sheets are conveyed one by one. Separation performance is very high.

On the other hand, in the above-mentioned paper feeding device, when the drive source is driven, the opposite direction torque is always applied to the separation roller through the torque limiter.
There was a problem that the load on the drive source was large. In particular, in recent years, an increasing number of types have a plurality of sheet feed units used in the image forming apparatus, such as 2 to 5 sheets, and are compatible with various sheet sizes. The load torque led to a larger drive source.

Therefore, Japanese Patent Application Laid-Open No. 6-183600 discloses a paper feeding device in which the size of the driving source is reduced by driving only the separation roller of the paper feeding table to be used.

[0006]

However, in the paper feeding device described in the above publication, a reverse torque is applied to the separation roller during the paper feeding operation, which imposes a drive load and also shortens the life of the drive source. There was a problem that it would be shortened.

The present invention solves the above-mentioned conventional problems,
The torque of the drive source during paper feeding can be greatly reduced,
Therefore, it is an object to provide a sheet feeding device and an image forming apparatus that can dramatically extend the life of a driving source.

[0008]

In order to solve the above-mentioned problems, the present invention provides a paper feed having a feed roller which is rotationally driven in a paper feeding direction, and a roller-shaped separating means which is pressed against the feed roller. In the device, the separating means is supported via a torque limiter,
The separating means is connected to a one-way clutch that allows rotation only in the paper returning direction.

According to the present invention, the separating means is supported by a separating shaft via a torque limiter, and an intermediate shaft connected to the separating shaft via a rotation transmitting means is provided. The separating shaft is provided on the intermediate shaft. A driving force for rotationally driving the means in the paper returning direction is transmitted, a drive for rotating the separating means of the intermediate shaft in the paper returning direction is transmitted, and an electromagnetic clutch for turning on / off the driving is provided. Is effective.

In order to solve the above-mentioned problems, the present invention provides an image forming apparatus including a paper feeding device according to a second aspect of the present invention, further comprising means for selecting ON / OFF of an electromagnetic clutch. It is characterized by being.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view of an image forming apparatus including a paper feeding device according to the present invention.

In FIG. 1, reference numeral 1 is a main body of an image forming apparatus, and a photosensitive drum 3 as an image bearing member is provided in an upper portion of the main body of the apparatus to form an image on the basis of a well-known electrophotographic process. An image forming unit 2 is provided for performing the operation. Below the image forming unit 2, a multi-stage sheet feeding device 10 is provided, and sheets are fed from the sheet feeding device 10 toward the image forming unit. The image forming apparatus main body 1 of this example is provided with a manual sheet feeding device 4 and a double-sided reversing unit 5.

In the above-mentioned image forming apparatus, the paper fed from the paper feeding device 10 or the manual paper feeding device 4 is sent to the registration roller 6, and the registration roller 6 causes the surface of the photosensitive drum 3 in the image forming section 2. The toner image is fed to the transfer portion in time with the toner image formed on the toner image. A transfer belt 7 is provided in the transfer section, and an unfixed toner image is transferred to the sheet sent to the transfer section, and is conveyed by traveling of the transfer belt 7 and is then conveyed to the fixing device 8. The sheet conveyed to the fixing device 8 has the unfixed toner image fixed as a permanent image by the action of, for example, heat and pressure, and after fixing, is selected and conveyed to either the sheet discharge section 9 or the reversing unit 5. .

FIG. 2 is an explanatory view showing the main part of the sheet feeding device 10 according to the present invention. In FIG. 2, reference numeral 21 is a feed roller that is rotationally driven in the paper feeding direction, and 22 is a feed roller.
Is pressed against the feed roller 21 and the torque limiter 2
5 is a separation roller as a separating unit that is rotationally driven in the direction of returning the sheet via 5 (see FIG. 3). In the sheet feeding device 10 of this embodiment, each sheet feeding stage adopts the FRR method. In the paper feeding device 10, when the paper feeding operation is started, the paper is sent out in the direction of arrow A by a pickup roller 23 which is arranged on a bundle of paper and is rotationally driven in the paper conveying direction, and then the feed roller 21 and the separation roller. It is clamped in the nip of 22. At this time, if the number of fed sheets is one, the separation roller 22 is rotated together by the feeding force of the feed roller 21, the sheet is fed as it is, and the feeding roller 24 as a feeding member.
It is conveyed to the registration rollers 7. Further, even if a plurality of sheets are fed, the separation roller 2
Since a predetermined torque is applied to 2 in the return direction,
The separation roller 22 rotates in the return direction to return the sheet in contact therewith, and only the uppermost sheet is separated and fed by the feed roller 21.

FIG. 3 is a perspective view showing a drive portion of the paper feeding device 10 according to the present invention, and FIG. 4 is an exploded explanatory view thereof. 3 and 4, in the sheet feeding device 10 of the present embodiment, a drive gear 31 driven by a motor (not shown) as a drive source for rotationally driving each roller is fixed to one end side of the intermediate shaft 32. It meshes with the gear 33 a of the separated geared electromagnetic clutch 33. The intermediate shaft 32 is rotatably supported by the case 50 via a separation one-way clutch 34 and a bearing 35, and a separation intermediate gear 36 is fixed in the middle thereof. The separation intermediate gear 36 is connected to the separation roller 22 via the torque limiter 25, and meshes with the separation driven gear 37 fixed to the separation roller shaft 22a supported by the case 50 via bearings 38 and 39. The separation one-way clutch 34 is configured such that the separation roller 22 allows rotation in the reverse direction, that is, only in the paper returning direction.

The gear 33a of the separation electromagnetic clutch 33 meshes with the gear 40a of the feed electromagnetic clutch 40 with a gear provided on the feed roller shaft 21a, and the feed roller shaft 21a is attached to the case 50 via the feed one-way clutch 41. It is supported. The pickup roller 23 is attached to the feed roller shaft 22a.
And a gear 42 that meshes with a pickup roller driven gear 44 via an idler 43. The feed one-way clutch 41 is configured so that the feed roller 21 is allowed to rotate only in the forward rotation direction, that is, in the paper conveyance direction.

In the sheet feeding device thus configured, when a sheet feeding command is issued, the drive motor of the sheet feeding unit (not shown) starts driving, the drive gear 31 rotates, and the separation electromagnetic clutch 33 is activated. By turning on both of the feed electromagnetic clutches 40, the feed roller shaft 21a and the intermediate shaft 32 are rotationally driven. By driving the feed roller shaft 21a, the feed roller 21 and the pickup roller 23 rotate in the sheet conveying direction, and by driving the intermediate shaft 32, a rotational force is transmitted to the separation roller 22 in the direction for returning the sheet via the torque limiter 25. . At this time, the feed roller 21 receives a reverse rotational force from the separation roller 22 corresponding to the slip torque value of the torque limiter 25, but the bearing supporting the feed roller shaft 21a allows only rotation in the conveying direction. Since it is the clutch 41, the feed roller 21 does not rotate in the reverse direction.

The feed roller 21 is driven by a signal when a sensor (not shown) detects that the leading edge of the fed sheet is nipped by the next conveying means, that is, the conveying roller 24 in the embodiment shown in FIG. Feed electromagnetic clutch 40
Is turned off, whereby the pickup roller 23 and the pickup roller 23 are stopped. On the other hand, the separation electromagnetic clutch 3
3 is turned on until the sheet is completely fed, and even if the sheet adsorbed by static electricity or the like is fed out with the leading end position deviated to the fed sheet, the separation roller 22 can prevent it.

By the way, in many paper feeding apparatuses having a plurality of paper feeding stages, all the paper feeding stages are driven from one drive source. Since the paper feeding apparatus of the present embodiment is provided with the separation electromagnetic clutch 33 and the feed electromagnetic clutch 40 when the paper feeding command is issued, the drive is transmitted to the non-selected paper feeding stages by the clutch off. Even if the number of paper feed stages is increased, the load on the drive source is small, and it is not necessary to increase the size. Further, it is advantageous that the separation roller 22 of the unselected paper feed stage rotates in the reverse direction and the leading end of the paper is damaged.

Further, since the electromagnetic clutch 33 is turned on in the selected paper feed stage, the drive source is loaded with the load. However, in recent years image forming apparatuses often use ordinary copy paper, and such paper is difficult to double feed because the coefficient of friction between papers is controlled. Therefore, constantly applying a reverse rotation torque to the separation roller 22 at the time of feeding paper wastes energy and shortens the life of the drive source accordingly.

Therefore, in the present embodiment, the bearing supporting the intermediate shaft 32 is provided with the separation one-way clutch 34 which allows only the reverse rotation in the paper feeding direction, and the separation electromagnetic is started even when the paper feeding operation is started. Clutch 3
Hold 3 in the off state. Here, when the feed electromagnetic clutch 40 is turned on, the pickup roller 23 rotates, and when one sheet is conveyed by this, the frictional force between the feed roller 21 and the sheet overcomes the torque value of the torque limiter 25 and the separation roller 22 moves. Followed rotation. Further, when two or more sheets are conveyed between the feed roller 21 and the separation roller 22, the torque value of the torque limiter 25 overcomes the frictional force between the sheets. As a result, torque is applied to the intermediate shaft 32 in the sheet conveying direction, but since the separation one-way clutch 34 is provided, the separation roller 22
Stops without rotating in the transport direction. Therefore, the double-fed sheet is stopped at the nip between the feed roller 21 and the separation roller 22.

Thus, in the present paper feeding device, double feed can be prevented without transmitting reverse rotation drive to the separation roller 22, so that the load on the drive source is reduced and the life is extended.

In the above-mentioned separation system, when a large number of sheets are conveyed to the nip between the feed roller 21 and the separation roller 22 at a time, the sheets cannot be separated and are fed. Since the coefficient of friction between sheets is suppressed to a low level, it is difficult to feed such a large number of sheets. Therefore, it is extremely effective when using a paper whose friction coefficient between papers is controlled to some extent, such as a normal copy paper.

However, various sheets are used in the image forming apparatus, and there are cases in which the sheet whose friction coefficient between sheets is not controlled is used. When feeding such paper,
By turning on the separation electromagnetic clutch 33, the FRR separation method can be selected, and by adopting the separation method, the risk of feeding multiple sheets can be greatly reduced. Therefore, the separation electromagnetic clutch 3 is installed in the image forming apparatus.
There is provided selection means (not shown) for allowing the user to select whether the FRR system is turned on by turning on 3 or the separation system is not turned on by the electromagnetic clutch 33. The selecting means may be arranged on a control panel or the like on which various keys of the image forming apparatus are arranged. However, by providing the tray on which the paper is set, a container of the cassette or the vicinity thereof, selection is made for each set paper. It is more convenient because it can be done.

[0025]

According to the first aspect of the present invention, the separating means is supported via the torque limiter, and the separating means is connected to the one-way clutch that allows rotation only in the paper returning direction. When the torque value of the torque limiter overcomes the separating means due to the double feeding, the separating means stops, so that the double feeding of the sheets can be prevented.

According to the second aspect, the separating means is supported by the separating shaft via the torque limiter, and an intermediate shaft connected to the separating shaft via the rotation transmitting means is provided, and the separating means is provided on the intermediate shaft. A driving force for rotationally driving the sheet in the sheet returning direction is transmitted, a drive for rotating the separating means of the intermediate shaft in the sheet returning direction is transmitted, and an electromagnetic clutch for turning on / off the driving is provided. Therefore, the separation system described in claim 1 and the FRR separation system can be provided.

According to the third aspect of the present invention, the means for selecting ON / OFF of the electromagnetic clutch is provided.
The separation method according to claim 1 and the separation method of FRR,
For example, it can be appropriately selected according to the type of paper.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus including a sheet feeding device according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a configuration of a paper feeding device according to the present invention.

FIG. 3 is a perspective explanatory view showing a configuration of a drive unit of the sheet feeding device.

FIG. 4 is a cross-sectional explanatory diagram of a drive unit in FIG.

[Explanation of symbols]

10 Paper feeder 21 Feed roller 22 Separation roller 32 Intermediate shaft 33 Separation electromagnetic clutch 34 separation one-way clutch 40-feed electromagnetic clutch

Claims (3)

[Claims] 1. A sheet feeding device having a feed roller which is rotationally driven in a paper feeding direction and a roller-shaped separating means which is pressed against the feed roller, wherein the separating means is supported via a torque limiter. Along with
A sheet feeding device, wherein the separating means is connected to a one-way clutch that allows rotation only in a sheet returning direction. 2. The sheet feeding device according to claim 1, wherein the separating means is supported by a separating shaft via a torque limiter, and an intermediate shaft connected to the separating shaft via a rotation transmitting means is provided. A driving force for rotationally driving the separating means in the paper returning direction is transmitted to the intermediate shaft, and a drive for rotating the separating means in the paper returning direction of the intermediate shaft is transmitted, and the drive is turned on. A sheet feeding device, which is provided with an electromagnetic clutch for turning off. 3. An image forming apparatus comprising the sheet feeding device according to claim 2, further comprising means for selecting ON / OFF of the electromagnetic clutch.