JPH0611997Y2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a sheet feeding device that uses a spring clutch to transmit drive to a roller, which is a so-called registration roller, that temporarily stops a conveyed sheet.

(Prior Art) The configuration of a conventional registration roller will be described by taking an automatic document feeder as an example. A registration roller used in an automatic document feeder that conveys a document onto the upper surface of the contact glass of the image forming apparatus, that is, a registration roller that temporarily stops the document by bringing the document conveyed from the paper feeding unit into contact with the nip point. The rotary shaft is supported by a pair of side plates inside the automatic document feeder via bearings.

Further, a spring clutch is rotatably supported at one end of the above-mentioned bearing for transmitting and disconnecting the drive to the registration roller, and a part of the spring clutch is locked by a locking mechanism provided in the vicinity thereof. Alternatively, the drive transmission to the registration rollers is switched by releasing or releasing the drive.

The structure of the spring clutch will be described with reference to FIG. 3. In the spring clutch, the fixing member 21 has a boss portion 21c, and one end 25b is locked in the locking hole 21a of the fixing member 21 and the fixing member 21 is fixed. A coil spring 25 that fits into the boss portion 21c, a ratchet wheel 23 that contains the coil spring 25 and has a groove 23a when the other end 25a of the coil spring 25 is locked, and a boss portion 24a that fits inside the coil spring 25. And a transmission gear 24 having.

Next, the function of the spring clutch 20 will be described with reference to FIGS. 1 and 3 which are sectional views showing an embodiment of the present invention. The fixing member 21 is fixed to the rotary shaft 1 by a screw 22, The rotation of the transmission gear 24 is always transmitted through the gear 13, and the locking mechanism is provided near the spring clutch 20.
A coil spring wound between the boss portion 24a of the transmission gear 24 and the boss portion 21c of the fixed member 21 when the locking arm 9 of the gear 30 is at the position indicated by the alternate long and short dash line, that is, at the position where it does not engage with the ratchet wheel 23. 2
5 contracts, both boss portions 21c and 24a are integrated, and the friction of the coil spring 25 causes the transmission gear 24 to be driven by a fixed member.
It is transmitted to the rotary shaft 1 via 21. On the other hand, when the locking arm 9 is at the position shown by the solid line, that is, at the position where it engages with the ratchet wheel 23, the ratchet wheel 23 is stopped by the locking arm 9 and therefore the ratchet wheel.
The other end 25a of the coil spring 25 locked to 23 is also stopped,
A force is applied in the direction in which the inner diameter of the coil spring 25 expands, the coil spring 25 and the boss portion 24a of the transmission gear 24 are in a loosely fitted state, and the rotational drive of the transmission gear 24 is not transmitted to the rotary shaft 1.

Next, the operation of the paper feed section of the automatic document feeder will be described with reference to the partial schematic sectional view of the automatic document feeder shown in FIG.

The original document s placed on the stack bypass 51 is fed to the main body of the automatic document feeder by the paper feed roller 52 and the paper feed rollers 42 and 43.
And is sent to the registration rollers 2 and 3. The registration rollers 2 and 3 are stopped until the original s comes into contact with the nip point, and the conveyance of the original s is started after the leading edge of the original s surely comes into contact with the registration rollers 2 and 3. This is to prevent oblique feeding to the main body of the automatic document feeder by temporarily controlling the leading edge of the original s.

Further, when the document s is conveyed by the registration rollers 2 and 3, the notch of the paper feed roller 42 is formed as shown in FIG.
The original s is in a state of facing 43, and the original s is in a state of being released from the paper feed rollers 42, 43.

Further, the original s sent out from the registration rollers 2 and 3 is carried to a predetermined position on the contact glass surface by the conveyor belt 53, and is discharged to the outside of the main body of the automatic document feeder after the copying process is completed. After that, the above operation is repeated until the original s is exhausted.

(Problems to be Solved by the Invention) As described above, one end of the rotary shaft of the registration roller for temporarily restricting the original is provided with a spring clutch for transmitting or disconnecting the drive to the roller, When a thick original such as a postcard that has been fed comes into contact with the registration roller, the registration roller rotates a predetermined angle in the original conveyance direction against the return force of the coil spring inside the spring clutch, and a constant return force is applied to the coil spring. Occur.

In this state, when the paper feed roller that was transporting the document to the registration roller comes into non-contact with the document as shown in FIG. 4, the restoring force of the coil spring causes the registration roller to move in the direction opposite to the transport direction. However, there is a problem in that the original that has rotated in the direction and is in contact with the registration roller is pushed back toward the paper feed roller, and the original is not conveyed from the registration roller, so-called a paper feed failure occurs.

The present invention is intended to provide a paper feeding device that solves the above problems.

(Means for Solving the Problem) The present invention is directed to a sheet feeding device that conveys the sheet further downstream after the leading edge of the sheet fed from the sheet feeding unit is brought into contact with a registration roller in order to achieve the above object. The registration roller is fixed to a rotating shaft, and the rotating shaft is supported by a pair of bearings, and one end of the rotating shaft is provided with a spring clutch that transmits or cuts off drive to the rotating shaft. The one-way clutch that prevents the rotating shaft from rotating in the direction opposite to the rotation for conveying the document by the restoring force of the coil spring built in the spring clutch is provided between at least one bearing and the rotating shaft. Alternatively, it is provided at least at one place between the transmission shaft and the rotary shaft that form a part of the spring clutch.

(Operation) According to the sheet feeding device configured as described above, when the leading end of the sheet is brought into contact with the nip point of the roller in order to temporarily regulate the sheet sent from the sheet feeding unit, the sheet rotates the roller. The restoring force of the coil spring of the spring clutch, which is generated by doing so, tends to rotate the roller in the opposite direction.

However, since the one-way clutch is provided at least at one place between at least one of the bearings and the rotary shaft, or between at least one of the transmission gear that forms a part of the spring clutch and the rotary shaft, the reverse of the roller is reversed. The rotation in the direction is restricted and the sheet is not pushed back.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of an automatic document feeder as an example of a sheet feeding device adopting the present invention, FIG. 2 is a sectional view of a one-way clutch, FIG. 3 is an exploded perspective view of a spring clutch, and FIG.
The figure is a partial schematic sectional view of the automatic document feeder.

The paper feeding operation of the automatic document feeder has been described above, and will be omitted.

FIG. 1 is a sectional view taken along the line AA of the registration roller portion shown in FIG. 4, in which the rotary shaft 1 is rotatably supported by the side plates 12 via bearings 4 and 7. A spring clutch 20 is provided at one end of the rotary shaft 1 which is fixed to one of the rollers 3 and which projects from the side plate 12. Further, the drive gear 13 is disposed at a position where it meshes with the transmission gear 24 that constitutes a part of the spring clutch 20, and drives the rotary shaft 1.

Further, in the vicinity of the spring clutch 20, there is provided a locking mechanism 30 for locking and unlocking a ratchet wheel 23 forming a part of the spring clutch 20, and the locking mechanism 30 is shown in FIG. As shown by the solid line in the figure, the transmission gear
The drive from 24 is not transmitted to the rotary shaft 1, and when the locking mechanism 30 is unlocked as shown by the chain line, the transmission gear 24
Rotates integrally with the rotary shaft 1.

Next, FIG. 2 is a sectional view taken along the line BB shown in FIG. 1, in which a one-way clutch 5 is press-fitted inside the bearing 4 as shown, and the rotary shaft 1 is oriented in the direction in which the original s is conveyed. Is configured to rotate, but not to rotate in the opposite direction.

Although the one-way clutch is press-fitted into the bearing as an embodiment of the present invention, the one-way clutch may be press-fitted into the boss portion of the transmission gear that forms a part of the spring clutch.

In this embodiment, the automatic document feeder is described as an example, but the present invention is also applicable to a sheet feeding device such as a copy sheet on the image forming apparatus main body side.

(Effect of the Invention) According to the present invention as described above, since the registration roller is fixed to the rotating shaft, it rotates in perfect synchronization with the shaft,
In this configuration, the one-way clutch is provided between at least one of the bearings and the rotary shaft or a transmission gear and the rotary shaft forming a part of the spring clutch without impairing the function as a registration roller that requires accurate conveyance timing. Since it is provided in at least one of the positions between and, when the leading edge of the sheet sent out from the sheet feeding unit contacts the registration roller, the restoring force of the coil spring built in the spring clutch is generated. Even if a rotational force in the direction opposite to the rotation for conveying the sheet is applied to the rotation shaft of the registration roller, the rotation is blocked, and the sheet contacting the registration roller is not pushed back to the paper feeding roller side.
Feeding failure is prevented.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an automatic document feeder adopting the present invention, FIG. 2 is a sectional view of a one-way clutch, FIG. 3 is an exploded perspective view of a spring clutch, and FIG. 4 is a partial schematic diagram of the automatic document feeder. FIG. Rotating shaft …… 1, bearing …… 4,7 Registration roller …… 2,3 Spring clutch …… 20 One way clutch …… 5

Claims (1)

[Scope of utility model registration request] 1. A sheet feeding apparatus for transporting a sheet fed from a sheet feeding section to a downstream side after abutting the leading edge of the sheet against the register roller, wherein the register roller is fixed to a rotary shaft, The shaft is supported by a pair of bearings, and a spring clutch is provided at one end of the rotary shaft to transmit or cut off the drive to the rotary shaft, and the return force of a coil spring built in the spring clutch is used. A one-way clutch that prevents the rotary shaft from rotating in the direction opposite to the rotation for carrying the sheet is provided between at least one bearing and the rotary shaft, or between the transmission gear and the rotary shaft forming a part of the spring clutch. A sheet feeding device, characterized in that it is provided at at least one of the positions.