JPH0826505A - Paper feeder - Google Patents

Abstract

PURPOSE:To provide a paper feeder equipped with a simple paper feed roller position control mechanism. CONSTITUTION:A paper feed mechanism 11, having rotary members 13, paper feed roller 14 provided coaxially with the rotary member 13 to have a circumference of large diameter and rollers 15 of small diameter rotatably provided in a side part in the vicinity of a boundary between a notched part and a circumferential part of the paper feed roller 14, is journalled to a shaft 12 and intermittently rotated by interrupting drive transmission from a drive system by a clutch. The paper feed roller 14 is rotated by the prescribed timing, to bring the circumferential part into press contact with paper P in the uppermost position, so as to feed the paper to a conveying path in the downstream. Here in a friction member 22, only a single sheet of the uppermost positioned paper P is separated. The paper feed mechanism 11 is rotated almost a little less than one turn by paper feed action and released from the drive transmission, to freely rotate in the same direction to at the time of paper feed action by the own weight of the roller 15 of small diameter, and it is brought into contact with the uppermost positioned paper in a paper cassette, to perform positioning an attitude of the paper feed roller 14 in a prescribed stop position.

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 having a sheet feeding roll position control mechanism having a simple structure.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus (hereinafter referred to as a main body apparatus) such as a printer or a copying machine, which stores a large number of fixed sheets in a sheet feeding cassette, the sheets stored in the sheet feeding cassette are In order to feed the sheet to the image forming unit, as shown in FIG. 4A, for example, as shown in FIG. 4A, a sheet feeding roller 2 having a peripheral surface made of an elastic member and a flat surface are provided in the main body apparatus at the front end of the sheet cassette 1 in the sheet feeding direction. There is a sheet feeding device provided with a separating member 3 having a friction surface. In this paper feeding device, the paper feeding roller 2 intermittently rotates in the clockwise direction to take out the paper P from the paper cassette 1, and the paper separating member 3 separates the paper P one by one and guides it.
The image is fed to the image forming unit via. Bottom plate 5 of paper cassette 1
Is pressed upward from below by an urging member (not shown), so that the front end in the feeding direction of the paper P stacked on the bottom plate 5 is pressed against the paper feed roll 2 at a constant pressure. Has become.

However, in the paper feeding device including the cylindrical paper feeding roller and the separating member, the intermittent rotation of the paper feeding roller may be temporally controlled, and there is no problem even if the stop timing is slightly shifted forward or backward. Since the rotation control is relatively easy, the elastic member of the next paper or the paper feed roller is always in pressure contact with the separating member even when the operation is stopped, so that unnecessary distortion is formed on the paper and each member. However, there is a problem that it adversely affects the subsequent printing operation.

As a solution to this problem, FIG.
As shown in FIG. 2, there is a sheet feeding device in which separation claws 6 are provided on both sides of the front end portion of the sheet cassette 1 in the sheet feeding direction, and a sheet feeding roller 7 in the main body device is formed so that the cross section has a half-moon shape. .
In this paper feeding device, the paper feeding roller 7 intermittently rotates clockwise in the same manner as described above to take out the paper P from the paper cassette 1, separate the paper P by the separating claw 6 and feed it to the image forming unit. To do. The paper feeding device including the half-moon-shaped paper feeding roller and the separation claw of the paper cassette does not require the arrangement of the separating member and can reduce the internal space, and the unnecessary distortion of the paper and each member during the operation stop. Although there is an advantage of not forming a habit, on the other hand, there is a tendency that the separation of the paper by the separation claw is often not correctly performed depending on the rotation timing of the paper supply roller. In addition, since the sheet feeding operation of the sheet feeding roller ends during the sheet feeding, there is also a drawback that the sheet is often skewed by the conveyance by the downstream conveying unit (not shown) which succeeds the sheet feeding operation.

From these things, as shown in FIG. 5 (a), a paper feeder of the eclectic type shown in FIGS. 4 (a) and 4 (b) has been considered. Figure (b) is a perspective view of the same, and Figure (c).
Shows a sectional view on the left and a side view on the right. Same figure (a) ~
The sheet feeding roller 8 shown in (c) is separated from both side surfaces of the half-moon shaped elastic member 8-1 similar to the sheet feeding roller shown in FIG. 4 (b) in the same manner as the sheet feeding roller shown in FIG. 4 (a). A rotary member 8-2 that is always in contact with the member 3 is provided, and these are coaxially supported and connected by a shaft 8-3. Also in the sheet feeding device in which the half-moon shaped elastic member and the circular rotating member are provided side by side, the sheet feeding roller 8 intermittently rotates in the clockwise direction to take out the sheet P from the sheet cassette 1 and one sheet is separated by the separating member 3. The sheets are separated and fed to the image forming unit. The above-mentioned half-moon shaped elastic member is released from the pressure contact immediately after feeding, while the rotating member is only in light contact with the paper and the friction member so as to sufficiently prevent double feeding of the paper immediately after feeding. No unnecessary distortion is formed on the paper or the friction member during the suspension of operation.

[0006]

However, even in the case of the sheet feeding device having the half-moon shaped elastic member and the circular rotating member, which are shown in FIGS. In order to correctly feed the paper, it is necessary to accurately control the stop position of the paper feed roller. For example, the half-moon shaped elastic member 8-1
Must be controlled so that the bottom surface portion (notch portion) becomes slanted and stops at a position that correctly faces the surface of the friction member 3 as shown by the solid line 8-1a in the figure. Generally, FIG.
As shown in FIG. 3, drive transmission to the rotary shaft 8-3 of the paper feed roller is performed by the drive system via the drive shaft 9 and the clutch 10.
The stop is controlled. However, with this alone, if it rotates too much in the clockwise direction indicated by the arrow A in the figure,
If the bottom portion may reach the position shown by the one broken line in the figure, the trailing end portion is still feeding from the sheet cassette 1 by the downstream transporting means (not shown) that has succeeded the sheet feeding operation. Unnecessary pressure contact is applied to a certain sheet P, and the sheet skews and induces print disturbance. On the other hand, if the bottom surface portion is at the position shown by the other broken line in the figure by stopping early in the counterclockwise direction indicated by arrow B, the half-moon shaped elasticity will be applied to the sheet conveyed while reversing upward in the guide 4. The ends of the member 8-1 come into irregular contact with each other, which similarly causes skewing of the sheet.

In order to accurately position the stop position of the paper feed roller, it is necessary to electrically perform rotation control by a pulse motor, braking control by an electromagnetic relay, etc., and mechanically. If there is, a deforming cam or the like interlocking with the rotating shaft is used to operate a lever or the like that engages with the deforming cam or the like to lock or unlock the ratchet or the like to the gear connected to the paper feeding roller shaft. I need to do that. In any case, there is a drawback that the drive transmission mechanism becomes complicated.

In view of the above situation, an object of the present invention is to provide a sheet feeding device provided with a simple position control mechanism for a sheet feeding roll.

[0009]

The structure of the sheet feeding device according to the present invention will be described below. The present invention has a rotating member axially rotatably rotatably supported, and a shape in which a part of the circumference that is provided coaxially with the rotating member and has a diameter larger than the diameter of the circumference of the rotating member is cut away. During the non-feeding operation of the paper, the notch is opposed to the topmost paper of the papers stacked on the paper storage member at a predetermined interval, and is rotated at a predetermined timing to press the circumference of the topmost paper into pressure contact. By doing so, it is possible to switch between a paper feed roller for feeding the paper to the downstream conveyance path and a rotational drive force from the drive system to the shaft of the paper feed roller so as to be transmitted or not transmitted. A drive transmission switching means for freely rotating the shaft during a non-paper feeding operation; a separating mechanism for separating the paper fed by the paper feeding roller sheet by sheet;
It is premised on a sheet feeding device provided with a conveying unit that conveys one sheet separated by the separating mechanism to a conveying path further downstream.

The sheet feeding device of the present invention is rotated to the side of the sheet feeding roller near the boundary between the notch and the circumference of the sheet feeding roller that first comes into contact with the sheet during the feeding operation of the sheet feeding roller. It is provided with a small-diameter roller that is freely provided and a positioning mechanism that positions the attitude of the paper-feed roller by bringing the small-diameter roller into contact with the uppermost sheet during non-feeding operation of the paper feed roller.

The small-diameter roller corresponds to the vicinity of the boundary between the cutout portion and the circumferential portion of the sheet feeding roller that first comes into contact with the sheet at the time of the sheet feeding operation of the sheet feeding roller. You may make it provide in the peripheral part of the side surface of the said rotation member. Further, the positioning mechanism is a mechanism in which a weight balance is set so as to move the small-diameter roller below the shaft by its own weight, as described in claim 3, for example.

[0012]

In the paper feeding device of the present invention, the small diameter roller is attached to the paper feeding roller or the rotating member by a mechanism in which a weight balance is set so as to move the roller below the shaft by its own weight. At the time of the non-feeding operation, the posture of the paper feed roller is positioned by contacting with the topmost paper.

[0013]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1A is a perspective view of a sheet feeding mechanism according to one embodiment, and FIG. 1B is a front view thereof. Same figure
As shown in (a) and (b), the sheet feeding mechanism 11 is provided with a rotating member 13 pivotally supported by a rotating shaft 12 which can be intermittently rotated by a drive system (not shown), and coaxially with the rotating member 13. A paper feed roller 14 having a circumference larger than the diameter of the circumference of the rotating member 13 and having a shape in which a part of the circumference is cut out, and a rotation on the side of the paper feed roller 14. It is provided with a small-diameter roller 15 provided freely.

The sheet feeding roller 14 faces the uppermost sheet P of sheets stacked on a sheet cassette, which will be described later, which is a sheet accommodating member, and keeps the above notches at a predetermined interval during the sheet non-feeding operation. The uppermost sheet P is rotated at a predetermined timing to press the circumferential portion of the sheet P into contact with the sheet P.
Is fed to the downstream transport path.

The small-diameter roller 15 is disposed on the side of the paper feed roller 14 in the vicinity of the boundary between the notch and the circumferential portion where the paper feed roller 14 first contacts the paper P during the feeding operation. Has been done.

A drive transmission switching means such as the clutch 10 shown in FIG. 6 is disposed between the rotary shaft 12 of the paper feed roller 14 and the drive system, and the rotary drive force from the drive system is provided. Can be intermittently added to the paper feed roller 14 in the transmission and non-transmission.

FIG. 2 is a sectional view of a printer having the above-mentioned paper feed mechanism 11. The printer 16 shown in FIG. 1 includes a rotating photosensitive drum 17, a charger for applying an electric charge to the photosensitive surface of the photosensitive drum 17, an LED head for exposing the photosensitive surface to which the electric charge is applied, and an exposure unit for this exposure. An image forming unit including a developing device for converting the electrostatic latent image formed on the photosensitive surface into a toner image, a transfer device for transferring the toner image onto a sheet, and a cleaner for removing the residual toner on the photosensitive surface after the transfer. 1
8 is provided downstream thereof, and a fixing section 19 including a heat-generating roll for thermally fixing the transferred toner image onto the sheet and a pressure-bonding roll is provided. A removable paper cassette 20 is attached to the bottom.

The sheet P of the sheet cassette 20 is urged from the bottom to the upper side by the bottom plate 21 of the sheet cassette 20, and is pressed against the circumferential portion of the sheet feeding roller 14 (see FIG. 1) of the sheet feeding mechanism 11 at the time of sheet feeding. The sheet is taken out from the uppermost portion by the sheet feeding roller 14, separated one by one by the friction member 22 which is a separating mechanism, turned upside down while passing through the sheet feeding guide 23, and further conveyed to the conveying path on the downstream side. The sheet is fed to the image forming unit 18 by a pair of conveying rolls 24 that is a conveying unit. The sheet P to which the toner image has been transferred by the image forming section 18 has the toner image thermally fixed by the fixing section 19, is reversed again by the discharge guide 25, and is discharged onto the discharge tray 26.

The paper feed mechanism 11 performs the above-mentioned paper feed operation.
When it rotates a little about once, the rotation drive transmission from the drive system is released by the clutch to be in a free rotation state, and the small diameter roller 15 is further rotated freely in the same direction as the paper feeding operation by the weight of the small diameter roller 15. The paper feed roller 14 is brought into contact with the uppermost paper of the cassette 20 and stopped with respect to the paper, whereby the posture of the paper feed roller 14 is positioned at a predetermined stop position.

At this time, the small-diameter roller 1 is provided at the rear end of the sheet P which is continuously fed by the pair of transport rolls 24 which have succeeded the sheet feeding operation after the sheet feeding operation by the sheet feeding roller 14 is completed.
5 is in contact with the paper feed roller 14, the paper P
Since it is separated from the surface, strong pressure is not applied to the paper P being fed, and therefore the torque on the transport side is reduced. On the other hand, when the rotating member 13 is brought into contact with the friction member 22 with an appropriate force (see FIG. 1 (a)), the next sheet to be fed that has been taken out to the lower surface of the sheet P will be friction member 22. The sheets are pressed against each other, which prevents the sheets from being fed in duplicate.

As described above, according to the present invention, the posture of the paper feed roller can be positioned at the optimum stop position by simply releasing the rotational drive transmission from the drive system to the paper feed roller by the clutch and allowing the paper feed roller to rotate freely. You can

In this embodiment, the case where the paper is separated sheet by sheet by the friction member 22 has been described as an example, but the present invention is not limited to the case where the paper separation mechanism is the friction member. It can also be applied when the separating mechanism is a separating claw.

This will be described below as another embodiment.
FIG. 3A is a front view of a paper feed mechanism according to another embodiment. The sheet feeding mechanism 30 shown in the figure has a rotating member 32 axially supported by a rotating shaft 31 which can be intermittently rotated by a drive system (not shown), and a circle of the rotating member 32 which is provided coaxially with the rotating member 32. A paper feed roller 33 having a circumference having a diameter larger than that of the circumference and having a shape in which a part of the circumference is cut out, and a small-diameter roller 34 provided around the side surface of the paper feed roller 33. It has and. In this embodiment, the rotary member 32 also has a shape in which a part of the circumference of the rotary member 32 is cut out, corresponding to the paper feed roller 33, like the paper feed roller 33. The small-diameter roller 34 is rotatably disposed at a position corresponding to the vicinity of the boundary between the cutout portion and the circumferential portion of the paper feed roller 33 on the peripheral portion of the side surface of the rotating member 32. Although not shown in particular, the paper feed mechanism 30 is also provided in a printer having a structure similar to that of the printer 16 shown in FIG. However, this printer is different in the separating mechanism from the printer 16 of FIG. That is, the friction member 22 shown in FIG. 2 is removed, and instead, separation claws are provided on both sides of the front end portion of the sheet cassette 20 in the sheet feeding direction.

In FIG. 3B, the paper cassette 20 in which the separation claw 35 is arranged, the paper P stacked in the paper cassette 20, and the above-mentioned paper feeding unit arranged facing the paper P surface. It is a perspective view which took out and showed only the paper mechanism 30.

Then, FIG. 6 (c) schematically shows a side view thereof. The drawing also shows the lower portion 36 of the paper feed guide of the printer body. As shown in FIGS. 8A to 8C, the small-diameter roller 34 is located near the boundary between the cutout portion and the circumferential portion that first come into contact with the paper P when the paper feeding roller 33 performs the feeding operation. The rotary member 32 is disposed at a peripheral position of the side surface of the corresponding rotary member 32.

In this case as well, the paper feed roller 33 makes the cutout portion face the uppermost paper sheet P stacked on the paper cassette 20 at a predetermined interval during the non-feeding operation of the paper sheet. The peripheral portion is pressed against the uppermost sheet by rotating at a predetermined timing, and the sheet P is fed to the conveying path on the downstream side. At this time, the separation claws 35, 35 separate only the topmost sheet.

The paper feed mechanism 30 also rotates slightly once in the paper feed operation described above, and then the rotational drive transmission from the drive system is released by a clutch or the like, and due to the weight of the small diameter roller 34, the same as in the paper feed operation. Rotate further in the direction, and the above small diameter roller 3
4 makes contact with the uppermost sheet of the sheet cassette 20, whereby the attitude of the sheet feeding roller 33 with respect to the sheet is positioned at a predetermined stop position without bringing the sheet feeding roller 33 into contact with the sheet P surface.

In this case as well, after the sheet feeding operation by the sheet feeding roller 33 is completed, the pair of transport rolls 24 which have succeeded the sheet feeding operation.
As a result, the small-diameter rollers 34 are separated from the right and left and abut with an appropriate force on the rear end portion of the paper P during continuous feeding, so that the skew of the paper P during feeding is prevented. You can

[0029]

As described above in detail, according to the present invention, the rotational drive transmission from the drive system to the paper feed roller is simply released by the clutch to be freely rotated.
The small-diameter roller contacts the sheet surface by its own weight, and the attitude of the sheet feeding roller can be positioned at a predetermined reference stop position.
As a result, the paper feed roller does not rotate too much or becomes insufficiently rotated from the reference stop position, and therefore, unnecessary press is applied to the paper surface during the paper feed operation, which adversely affects the conveyance. There is no. Further, since the paper feed roller is properly stopped at the reference stop position, the paper feeding operation of the next paper is performed at the correct timing, and therefore the occurrence of printing defects and the like is reduced. Moreover, since the paper feed roller can be positioned at the reference stop position by the paper feed mechanism having an extremely simple structure, complicated connection / disconnection control of the drive system by electric drive control or braking control or mechanical cams, levers, ratchets, etc. Therefore, the complicated connection / disconnection control of the drive system is not required. Therefore, the number of parts is reduced, the product cost is reduced, the installation space is reduced, and the device is downsized. In addition, the simple structure improves the efficiency of assembly work in the factory and reduces the failure rate during use.

[Brief description of drawings]

FIG. 1A is a perspective view of a sheet feeding mechanism according to an embodiment,
(b) is a front view thereof.

FIG. 2 is a cross-sectional view of a printer including the paper feed mechanism of FIG.

FIG. 3A is a front view of a sheet feeding mechanism according to another embodiment,
(b) is a perspective view showing a positional relationship with a paper cassette in which separation claws are arranged, and (c) is a side view thereof.

4A and 4B are perspective views respectively showing an example of a conventional sheet feeding device.

FIG. 5 (a) is a side sectional view of a conventional improved paper feeder, and FIG.
Is a perspective view thereof, and (c) is a sectional view and a side view seen from the front.

FIG. 6 is a diagram illustrating a clutch that connects and disconnects drive transmission.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper cassette 2 Paper feed roller 3 Separation member 4 Guide 5 Bottom plate 6 Separation claw 7, 8 Paper feed roller 8-1 Half moon elastic member 8-2 Rotating member 8-3 Shaft 10 Clutch 11, 30 Paper feed mechanism 12, 31 Rotating shaft 13, 32 Rotating member 14, 33 Paper feeding roller 15, 34 Small diameter roller 16 Printer 17 Photoreceptor drum 18 Image forming unit 19 Fixing unit 20 Paper cassette 21 Bottom plate 22 Friction member 23 Paper feed guide 24 Conveying roll pair 25 Paper ejection Guide 26 Output tray P Paper

Claims (3)

[Claims] 1. A rotating member axially rotatably supported by rotation, and a shape which is provided coaxially with the rotating member and has a part of a circumference having a diameter larger than a diameter of a circumference of the rotating member is cut out. However, during the non-feeding operation of the paper, the cutout portion is made to face the uppermost paper of the sheets stacked on the paper storage member at a predetermined interval and is rotated at a predetermined timing so that the circumferential portion is formed on the uppermost paper. A sheet feeding roller that feeds the sheet to a downstream conveying path by pressing it, and a rotational driving force from a drive system can be switched between transmitted and non-transmitted to the shaft of the sheet feeding roller. Drive transmission switching means for freely rotating the shaft during the non-paper feeding operation, a separating mechanism for separating the paper fed by the paper feeding roller sheet by sheet, and one sheet separated by the separating mechanism. Transporting means for transporting to a further downstream transport path, In the paper feeding device, a small diameter rotatably provided on the side of the paper feeding roller near the boundary between the cutout portion and the circumferential portion of the paper feeding roller that first comes into contact with the paper during the feeding operation of the paper feeding roller. A sheet feeding device comprising: a roller; and a positioning mechanism that positions the orientation of the sheet feeding roller by bringing the small-diameter roller into contact with the uppermost sheet when the sheet feeding roller is not feeding. 2. The small-diameter roller corresponds to a peripheral portion of a side surface of the rotating member corresponding to a vicinity of a boundary between a cutout portion and a circumferential portion of the paper feed roller that first comes into contact with a sheet during a feeding operation of the paper feed roller. The sheet feeding device according to claim 1, wherein the sheet feeding device is provided in the. 3. The sheet feeding device according to claim 1, wherein the positioning mechanism is a mechanism in which a weight balance is set so as to move the small diameter roller below the shaft by its own weight.