JP2883829B2 - Sheet feeding device and image forming device - Google Patents

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 for feeding sheets one by one from a sheet feeding unit of a sheet feeding cassette or a multi-tray of an image forming apparatus such as a copying machine, a printer, a facsimile or the like. The present invention relates to a sheet feeding device provided with a gear rotation transmitting device for intermittently transmitting a rotating force to a sheet feeding device.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine, a printer, a facsimile or the like is provided with a sheet feeding apparatus for separating stacked sheets one by one and feeding the separated sheets to an image forming unit.

A conventional sheet feeding apparatus will be described with reference to FIGS. 9 is a perspective view showing a rotation drive transmission mechanism for one rotation control of a multi-feed roller using a conventional spring clutch mechanism, FIG. 10 is a front sectional view of FIG. 9, and FIGS. 11 and 12 are side views of FIG. FIG. In the figure, the driving force of the driving gear 17 is applied to the half-moon feeding roller 1 by the spring clutch gear 5.
As a result, the power is transmitted as rotation power of one rotation intermittent drive.

The half-moon feeding roller 1 and the eccentric cam 6 are fixed to the feeding shaft 11, and before the start of feeding, the spring stopper ring 8 causes the half-moon feeding roller 1 to be out of contact with the separation pad 4. With the eccentric cam 6 pushing down the plate 3 during feeding in the lowermost position, the position is adjusted so that the armature 18a of the solenoid 18 is caught by the notch 7a of the control ring 7, and the sheet is fed by the set screw 9. It is fixed to the shaft 11.

At this time, the clutch spring 10 provided between the control ring 7, the spring stopper ring 8 and the spring clutch gear 5 is in a loosened state, and the spring clutch gear 5
It is in a rotation-free state with respect to 11.

The sheet feeding middle plate 3 is fixed to a middle plate arm 19 and is provided so as to be swingable about a rotation shaft 22.
Is pressed against the eccentric cam 6 by a middle plate pressing spring 21.

As shown in FIG. 11, the eccentric cam 6 has a portion 6a having a radius r centered on the sheet feeding shaft 11. When the roller 20 is located at the portion 6a, the sheet feeding plate 3 is pushed down to the lowest position. In this state, the pressing force of the intermediate plate pressing spring 21 acts in the direction of the center of the sheet feeding shaft 11, so that the sheet feeding shaft 11 maintains a balance without rotating.

Now, when the solenoid 18 is energized and the armature 18a is pulled from the paper feed start standby state in FIG. 11, the notch 7a of the control ring 7 is disengaged, and the clutch spring 10 in the control ring 7 is moved by the paper feed shaft 11a. By slightly rotating in the rotation direction, the spring clutch gear 5 and the spring retaining ring 8 are tightened.

Thus, the spring clutch gear 5 eccentric cam 6, control ring 7, clutch spring 10, spring stopper ring 8, paper feed shaft
11. The half-monthly feeding roller 1 rotates once as a unit, and after one rotation, the notch 7a of the control ring 7 is again caught by the armature 18a of the solenoid 18, the rotation of the control ring 7 stops, and the clutch spring 10 is loosened. Therefore, the spring clutch gear 5 becomes free to rotate again.

Here, when the eccentric cam 6 rotates from the paper feed start standby state in FIG. 11 and the roller 20 comes off from the portion 6a of the eccentric cam 6, the feeding plate 3 presses the pressing plate spring 21. The recording sheet P loaded on the plate 3 is fed up by the pressure until the top surface of the recording sheet P hits the side rollers 13, 14 or the circular portion of the half-moon feeding roller 1.

At this time, the eccentric cam 6 which rotates integrally with the half-moon feeding roller 1, the feeding shaft 11, and the spring stopper ring 8 is free to rotate in the drive transmitting direction. The spring 21 is instantaneously rotated to the state shown in FIG. 12 by the pressing force of the spring 21 (the direction of the arrow a in FIG. 11). At this time, the spring clutch gear 5 is free to rotate in the direction opposite to the drive transmission direction.

Thereafter, the recording paper P stacked on the feeding middle plate 3 is pressed against the circular portion of the half-moon feeding roller 1 by a middle plate pressing spring.
21 and is conveyed with the rotation of the paper feed roller 1.

[0013]

In the above-described conventional sheet feeding apparatus, the rotation of the half-moon feeding roller 1 and the swinging of the feeding middle plate 3 by the eccentric cam 6 coaxial with the half-moon feeding roller 1 are intermittently performed. For driving, a spring clutch mechanism including a spring clutch gear 5, a control ring 7, a spring stopper ring 8, a clutch spring 10, and a solenoid 18 has been used.

However, the spring clutch mechanism is free to rotate in the direction opposite to the drive transmission direction, and there is a problem that the half-moon feeding roller 1 and the eccentric cam 6 coaxial with it are rotated in the drive transmission direction by an external force. Was.

That is, when the pressing force of the middle plate pressing spring 21 acts on the eccentric cam 6 via the roller 20, the eccentric cam 6 rotates without controlling the jumping movement of the sheet feeding middle plate 3, and The feeding plate 3 that jumped up vigorously was the side roller 13,
14 or half a month, it rebounds by hitting the paper feed roller 1 and causes a paper feed failure without applying the proper paper feed pressure, or causes image defects such as image pitch unevenness due to blur due to the impact of a collision. There was a problem that noise was generated at the time of paper.

The present invention solves the above problems,
The purpose is to prevent the feeding shaft from rotating freely in the drive transmission direction, thereby controlling the jumping of the sheet mounting plate to prevent the occurrence of blur and noise due to the impact of the collision, This makes it possible to prevent defective feeding.

[0017]

In order to achieve the above object, a typical configuration according to the present invention is such that when the sheet mounting plate is raised, the sheet on the sheet mounting plate is moved relative to the feeding rotating body. In the sheet feeding apparatus configured to apply a feeding pressure to a sheet by being pressed by pressing, a feeding shaft that supports the feeding rotating body and transmits a driving force and moves the sheet mounting plate up and down. An eccentric cam that is fixedly supported on the feed shaft, a spring clutch mechanism that controls the rotation of the feed shaft,
A rotation control means comprising a one-way clutch is provided between the feed shaft and the spring clutch so that the feed shaft does not become free to rotate in the drive transmission direction.

Further, an image forming apparatus according to the present invention includes the sheet feeding device and recording means for forming an image on a sheet fed from the sheet feeding device in accordance with image information. And

[0023]

Since the sheet feeding apparatus according to the present invention is constructed as described above, the sheet feeding device to which the feeding rotary member and the eccentric cam are fixed does not rotate freely in the drive transmitting direction. Since the one-way clutch is provided between the feed shaft and the spring clutch gear, the one-way clutch controls the rotation of the feed shaft.

Further, the image forming apparatus provided with the sheet feeding device according to the present invention exerts the function of the sheet feeding device to control the jumping of the sheet placing plate to reduce the blur due to the impact of the collision. Noise can be prevented, and an image can be recorded on a well-fed sheet.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a laser beam printer provided with a Duplo-type multi-sheet feeding device and a claw-separation type cassette feeding device as an example of a sheet feeding device and an image forming device according to the present invention is shown. 5 shows a rotation drive transmission mechanism for one rotation control of a multi-feed roller using a spring clutch system as a feeding device.

The present invention is characterized in that the paper feed roller and the rotation control means are provided so that the feed shaft to which the eccentric cam is fixed does not rotate freely in the drive transmission direction. As means, first, an example using a toothless gear as a reference example will be described with reference to FIGS. 1 to 6, and then an example using a one-way clutch will be described with reference to FIGS. 7 and 8 as an embodiment of the present invention. Will be explained. FIG. 1 is a cross-sectional explanatory view of a laser beam printer provided with a sheet feeding device according to the present invention. FIG. 2 is a reference example of the sheet feeding device. FIG. 3 is a perspective view showing the transmission mechanism, FIG. 3 is a front sectional view of FIG. 2, and FIG.
6 are operation progress diagrams viewed from the side of FIG. In the following description, the recording paper P is used as a sheet, but it is needless to say that the present invention can be applied to various sheets made of synthetic resin or the like.

In FIG. 1, recording papers P stacked on a multi-tray 400 are picked up and conveyed by a semi-monthly paper feed roller 1 serving as a feeding rotary member, and separated by a separation pad 4 one by one. Then, only the uppermost recording sheet P is conveyed to the registration roller pair 52 along the pre-registration guide 51.

Similarly, the recording papers P stacked in the cassette 500 are separated by a separation claw 12 by the separation pawls 12 and the recording papers P picked up and conveyed by the half-moon feeding roller 2 serving as a feeding rotary member. Only the uppermost recording paper P is conveyed to the registration roller pair 52 along the pre-registration guide 51.

The recording paper P is conveyed by a pair of registration rollers 52 in accordance with the rotation of a photosensitive drum 53 as an electrophotographic photosensitive member disposed in a process cartridge 300 serving as a recording means. The toner image on the photosensitive drum 53 is transferred onto P.

Thereafter, the recording paper P is guided by the separation guide 55, the conveyance guide 56, and the entrance guide 57, and is heated and pressed by the roller pair of the fixing roller 58 and the pressure roller 59, so that the toner image on the recording paper P becomes permanent. Fixes as an image.

At this time, since the recording paper P is wrapped around the fixing roller 58, the recording paper P is forcibly separated by the separating claw 60 and is fixed to the fixing discharge roller.
The sheet is transported by the transport guide ribs 64 and 61. Further, the recording paper P is conveyed along conveyance guides 66 and 67 by a conveyance roller pair 65, and is a discharge device which also serves as a curl removing device.
The paper is discharged and stacked on the face down tray T via 68.

Next, a reference example in which a toothless gear is provided as a rotation control means so that the half-moon feeding roller 1 and the feeding shaft 11 to which the eccentric cam 6 is fixed does not rotate freely in the drive transmission direction. explain. 2 and 3, the driving force of the driving gear 17 is transmitted to the half-moon feeding roller 1 by the spring clutch gear 5 as rotation power of one rotation intermittent driving. The half-moon feeding roller 1, the eccentric cam 6, and the feeding missing gear 16 are fixed to the feeding shaft 11 serving as the feeding shaft.

As shown in FIG. 4, before the sheet feeding is started, the spring stopper ring 8 is in a state where the half-monthly feeding roller 1 is not in contact with the separation pad 4, and the eccentric cam 6 is in contact with the sheet placing plate. When the feeding plate 3 is pushed down to the lowermost position, the position of the armature 18a of the solenoid 18 is adjusted so that the notch 7a of the control ring 7 is hooked.
And is fixed to the paper feed shaft 11.

At this time, the clutch spring 10 provided between the control ring 7, the spring stopper ring 8 and the spring clutch gear 5 is in a loosened state, and the spring clutch gear 5
It is in a rotation-free state with respect to 11. In addition, since the feed missing gear 16 is fixed to the feed shaft 11 at a position where the missing tooth portion 16a faces the drive gear 17, the rotational driving force of the drive gear 17 is not transmitted to the feed shaft 11. .

The sheet feeding middle plate 3 is fixed to a middle plate arm 19 and is provided so as to be swingable about a rotation shaft 22.
Roller 20 provided on the eccentric cam 6
Is pressed against.

As shown in FIG. 4, the eccentric cam 6 is provided with a portion 6a having a radius r centered on the sheet feeding shaft 11, and when the roller 20 is located at the portion 6a, the sheet feeding plate 3 is pushed down to the lowest position. In this state, the pressing force of the middle plate pressing spring 21 acts in the direction of the center of the sheet feeding shaft 11, so that the sheet feeding shaft 11 maintains a balance without rotating.

Further, side rollers 13 and 14 are rotatably provided on both sides of the half-moon feeding roller 1 on the feeding shaft 11.
The separation pad 4 is attached so as to be swingable about a rotation shaft 23, and is pressed against the side rollers 13 and 14 by a separation pad pressing spring 15. Here, the diameter of the side rollers 13 and 14 is slightly smaller than the diameter of the circular portion of the half-moon feeding roller 1.

Now, when the solenoid 18 is energized and the armature 18a is pulled from the paper feed start standby state shown in FIG.
Of the clutch spring in the control ring 7
10 rotates slightly in the paper feed shaft rotation direction and the spring clutch gear 5
And the spring retaining ring 8 is tightened.

Thus, the spring clutch gear 5, the eccentric cam 6, the paper feed missing gear 16, the control ring 7, the clutch spring 10, the spring stopper ring 8, the paper feed shaft 11, and the semicircular paper feed roller 1 are integrated. After one rotation, the notch 7a of the control ring 7 is again caught by the armature 18a of the solenoid 18, the rotation of the control ring 7 stops and the clutch spring 10 is loosened, so that the spring clutch gear 5 becomes free to rotate again. , Feed missing gear
16 returns to the initial state when the missing tooth portion 16a comes to the position facing the drive gear 17 again.

When the eccentric cam 6 rotates from the paper feed start standby state shown in FIG.
As shown in FIG. 5, a rotational force acts on the eccentric cam 6 in the direction of arrow b in FIG.

However, unlike the above-mentioned conventional example, the sheet feeding toothless gear 16 rotates simultaneously with the eccentric cam 6 and the toothed portion 16b of the sheet feeding toothless gear 16 starts to mesh with the driving gear 17, so that the eccentricity is obtained. The cam 6, the paper feed shaft 11, and the semi-circular paper feed roller 1 are not in a rotation-free state in the drive transmission direction, and follow the drive gear 17, so that the roller 20 moves along the outer diameter of the eccentric cam 6.

Accordingly, the sheet 3 during feeding is gradually lifted in accordance with the timing of sheet feeding without being vigorously jumped up by the pressurizing spring 21, and the recording paper P on the sheet 3 during feeding is moved side by side. It is pressed against the circular portion of the paper feed roller 1, 13, or 14.

Thereafter, the recording paper P stacked on the middle feeding plate 3 is pressed against the circular portion of the half moon feeding roller 1 by the middle plate pressing spring 21 and is conveyed with the rotation of the half moon feeding roller 1. Then, the recording paper P conveyed by the half-moon feeding roller 1 is separated one by one by a separation pad 4 as shown in FIG. 6, and only the uppermost recording paper P is transferred to the registration roller pair 52 along the registration front guide 51. Conveyed.

Next, as a sheet feeding device according to the present invention,
An embodiment using a one-way clutch as the rotation control means will be described with reference to FIGS. The same members as those of the reference example are denoted by the same reference numerals, and description thereof is omitted. FIG. 7 is a perspective view showing one rotation intermittent drive transmission mechanism of a Duplo-type multi-feed roller using a spring clutch mechanism in an embodiment of the sheet feeding apparatus according to the present invention, and FIG.
FIG.

In FIG. 7, a one-way clutch 24 is provided between the spring clutch gear 5 and the paper feed shaft 11 so that the paper feed shaft 11 does not become free to rotate in the drive transmission direction. 7, the spring clutch gear 5 is free to rotate with respect to the paper feed shaft 11 only in the drive transmission direction.

In this state, when the solenoid 18 is energized and the armature 18a is pulled, the notch 7a of the control ring 7 is disengaged, and the clutch spring 10 in the control ring 7 is slightly rotated in the direction of rotation of the paper feed shaft 11 so that the spring is rotated. Tighten the clutch gear 5 and the spring stopper ring 8.

Thus, the spring clutch gear 5, the eccentric cam 6, the control ring 7, the clutch spring 10, the spring stopper ring 8, the paper feed shaft
11. The half-monthly feeding roller 1 rotates once as one body, and after one rotation, the notch 7a of the control ring 7 is again caught by the armature 18a of the solenoid 18, the rotation of the control ring 7 stops, and the clutch spring 10 loosens. Therefore, the spring clutch gear 5 becomes free to rotate only in the drive transmission direction again.

The eccentric cam 6 is also locked in the drive transmission direction because the paper feed shaft 11 is locked in the drive transmission direction with respect to the spring clutch gear 5 by the function of the one-way clutch 24. The paper feed shaft 11 and the semi-circular paper feed roller 1 do not rotate freely in the drive transmission direction, and follow the drive gear 17 via the spring clutch gear 5, so that the roller 20 moves along the outer diameter of the eccentric cam 6. Moving.

Therefore, as described above, the sheet feeding plate 3 does not jump up vigorously by the sheet pressing spring 21 and rises gently in synchronization with the sheet feeding timing. The paper P is the side rollers 13, 14 or half-moon feeding roller 1
Is pressed against the circular part of.

In the above embodiment, the case where the sheet feeding apparatus according to the present invention is applied to the multi-feeding apparatus of the Duplo system related to the half-month feeding roller 1 has been described. It is also possible to apply to a cassette sheet feeding device related to the paper roller 2.

[0052]

Since the sheet feeding apparatus according to the present invention has the above-described configuration and operation, the feeding shaft to which the feeding rotating body and the eccentric cam are fixed is not rotated in the drive transmitting direction. As a rotation control means, a one-way clutch is provided between the feed shaft and the spring clutch gear, so that the one-way clutch controls the rotation of the feed shaft, and the eccentric cam rotates according to the rotation of the drive gear to place the sheet. The plate moves upward as the eccentric cam rotates.

The following effects can be obtained by the sheet feeding device provided with the above-described rotation control means.

1. There is no rebound of the sheet placing plate due to collision with the side rollers or the feeding rotating body, and the feeding pressure operates stably, so that feeding failure can be reduced.

2. Since there is no blur due to the collision, image defects such as image pitch unevenness due to a shock at the time of feeding do not occur.

3. Since there is no collision, there is no noise at the time of feeding and quiet.

Further, the image forming apparatus provided with the sheet feeding device can record an image on the fed sheet by exerting the function of the sheet feeding device. Therefore, it is possible to provide an image forming apparatus that generates less noise, has less feeding defects, and has less image defects.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of a laser beam printer having a Duplo sheet feeding device.

FIG. 2 is a perspective view showing a one-rotation intermittent drive transmission mechanism of a Duplo-type multi-sheet feed roller using a spring clutch mechanism in a reference example of the sheet feeding apparatus according to the present invention.

FIG. 3 is a front sectional view of FIG. 2;

FIG. 4 is an operation progress diagram viewed from the side of FIG. 2;

FIG. 5 is an operation progress diagram viewed from the side of FIG. 2;

FIG. 6 is an operation progress diagram viewed from the side of FIG. 2;

FIG. 7 is a perspective view showing a one-rotation intermittent drive transmission mechanism of a Duplo-type multi sheet feed roller using a spring clutch mechanism in the embodiment of the sheet feeding apparatus according to the present invention.

FIG. 8 is a front sectional view of FIG. 7;

FIG. 9 is a diagram illustrating a conventional example.

FIG. 10 is a diagram illustrating a conventional example.

FIG. 11 is a diagram illustrating a conventional example.

FIG. 12 is a diagram illustrating a conventional example.

[Explanation of symbols]

1, 2 ... half-moon feeding roller, 3 ... feeding plate, 4 ... separation pad, 5 ... spring clutch gear, 6 ... eccentric cam, 7 ... control ring, 7a ... notch, 8 ... spring stop ring, 9 ... Set screw,
10 ... clutch spring, 11 ... paper feed shaft, 12 ... separation claw, 13, 14 ...
Side roller, 15: Separation pad pressure spring, 16: Missing gear for feeding paper, 16a: Missing tooth portion, 16b: Geared portion, 17: Drive gear,
18 ... solenoid, 18a ... armature, 19 ... middle plate arm, 20 ... roller, 21 ... middle plate pressing spring, 22, 23 ... rotating shaft, 24
... one-way clutch, 51 ... guide before registration, 52 ... pair of registration rollers, 53 ... photosensitive drum, 54 ... transfer roller, 55 ...
Separation guide, 56: conveyance guide, 57: entrance guide, 58: fixing roller, 59: pressure roller, 60: separation claw, 61, 62: fixing discharge roller, 64: conveyance guide rib, 65: conveyance roller pair,
66, 67: transport guide, 68: discharge device, 300: process cartridge, 400: multi-tray, 500: cassette, T
… Face down tray, P… Recording paper

Claims (2)

(57) [Claims] In a sheet feeding apparatus, when a sheet mounting plate is lifted, a sheet on the sheet mounting plate is pressed against a feeding rotating body to apply a feeding pressure to the sheet. A feed shaft that supports the feed rotator and transmits a driving force; an eccentric cam fixedly supported on the feed shaft for vertically moving the sheet mounting plate; A spring clutch mechanism for controlling the rotation of a shaft, a rotation control means comprising a one-way clutch provided between the feed shaft and the spring clutch so that the feed shaft does not rotate freely in the drive transmission direction, A sheet feeding device comprising: 2. An image, comprising: the sheet feeding device according to claim 1; and recording means for forming an image on a sheet fed from the sheet feeding device in accordance with image information. Forming equipment.