JPH0240044Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an image forming apparatus such as a copying machine, and particularly relates to an improvement of a paper feeding device.

[Prior art and its problems]

Conventionally, as a method of feeding paper one sheet at a time in a paper feeding device such as a copying machine, the topmost sheet of paper is once retracted and evacuated from the leading end presser member, and then the paper is fed in the direction in which it should be fed. is widely known.

A conventional paper feeding device will be described below with reference to the accompanying drawings.

FIGS. 2a to 2c are configuration diagrams showing a conventional paper feeding device. The paper feeding device is composed of a paper feeding roller 1, a timing roller 6, and a paper feeding cassette 7, and the paper feeding cassette 7 is composed of a paper 2, a push-up plate 3, a leading edge pressing member 4, and a trailing edge regulating plate 5. ing.

Here, the paper push-up plate 3 is pivotally supported with its rear end as a fulcrum, and is biased clockwise by biasing means (not shown). In addition, a large number of sheets of paper 2
is pressed against the paper feed roller 1, which can be rotated in forward and reverse directions, with an appropriate pressure by the biasing force. In order to prevent two sheets of paper 2 from being fed and to accurately feed one sheet at a time, a leading edge pressing member 4 is provided which abuts the leading edge of the stacked sheets of paper 2 with its own weight.

First, the paper feed roller 1 is moved as shown in FIG. 2b.
When the stacked sheets 2 are rotated counterclockwise, the rear ends of the stacked sheets 2 are regulated by the rear end regulating plate 5, so that the uppermost sheet is bent and separated from the other sheets.
When the top sheet of paper is sufficiently retreated from the leading end presser member 4, the paper feed roller 1 starts rotating clockwise as shown in FIG. send out.

The leading edge of the fed sheet comes into contact with the stopped timing roller 6, and after forming an appropriate bend in the sheet 2, the sheet feeding roller 1 stops.

Next, the timing roller 6 starts rotating at an appropriate timing to nip and convey the paper 2.

In the paper feeding device having the above structure, the timing roller 6 must be configured so that when the timing roller 6 rotates to nip and transport the paper, the paper feeding roller 1 does not apply an excessive load to the paper being transported.

For this purpose, the paper feed roller 1 is driven by a motor capable of forward and reverse rotation, and an electromagnetic clutch is interposed between the motor and the paper feed roller 1.
The electromagnetic clutch is turned on only when the rotation is reversed, and turned off at other times. Further, the paper feed roller 1 is provided to be movable up and down, and after the paper is clamped by the timing roller 6, a measure is taken to move the paper feed roller 1 upward to break contact with the topmost paper. was.

However, a disadvantage of such conventional sheet feeding devices is that they are expensive because they use two electrical components, a drive motor and an electromagnetic clutch. Furthermore, since two electrical components are controlled, the circuit configuration is complicated.

Furthermore, the vertical movement mechanism for raising and lowering the paper feed roller 1 is complicated and requires a large number of mechanical parts, which increases the number of parts and increases costs.

[Purpose of invention]

In view of the above-mentioned drawbacks of the conventional art, the present invention provides a paper feeding device that controls forward and reverse rotation using a drive source capable of forward and reverse rotation and a simple mechanism, and that does not place an excessive load on the paper feeding roller. With the goal.

[Key points of the idea]

In order to achieve the above object, the present invention includes a paper feeding means that contacts the uppermost sheet of the stacked papers, and a presser member that contacts the leading edge of the uppermost sheet, and the present invention includes Paper feeding in which the uppermost sheet is moved backward by a conveying force to retract the leading edge of the uppermost sheet from the presser member, and then the sheet is advanced and fed by a forward conveying force of the sheet feeding means. In the apparatus, the drive source of the paper feeding means is a drive source capable of forward and reverse rotation, and the means for transmitting forward conveying force from the drive source to the paper feeding means transmits only the forward rotation drive of the drive source. The apparatus is characterized in that the means for transmitting the backward conveying force from the drive source to the sheet feeding means is a drive transmitter for transmitting only the reverse drive of the drive source.

[Example of idea]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIGS. 1 and 3 are a perspective view and a sectional view of a driving section of a paper feeder according to the present invention.

The driving section of the paper feeding device is composed of a motor, a gear, a paper feeding shaft, a ratchet plate, ratchet teeth, a cylindrical member, and a paper feeding roller.

A cylindrical member 11 is supported by a one-way bearing 21 on the paper feed shaft 17 so as to be rotatable in only one direction. Further, a paper feed roller 12 is fixed to the outer circumferential surface of the cylindrical member 11, which presses against the uppermost sheet of the stacked sheets and retracts and feeds the sheet.

On the other hand, the one-way bearing 21 that supports the cylindrical member 11 transmits the rotational force of the paper feed shaft 17 only when the paper feed shaft rotates in the paper feeding direction, and transmits the rotational force when the paper feed shaft rotates in the backward direction of the paper. Don't communicate.

A ratchet plate 13 is fixed to the other end of the cylindrical member 11, facing the gear B14, and ratchet teeth 13a are provided upright on the ratchet plate 13. The gears include a gear A18 and a gear B14, and the gear B14 is provided on the paper feed shaft 17 so as to be rotatable and slidable with respect to the paper feed shaft 17. However, the gear B14 is provided with a groove 15 that is inclined with respect to the axial direction, and the pin 1 passes through the groove 15.
6 is installed upright on the paper feed shaft 17, so the paper feed shaft 17
The amount of rotation and sliding relative to each other is limited. The gear B14 also has ratchet teeth 14a.
The ratchet teeth 14a are provided so as to be able to mesh with the ratchet teeth 13a of the ratchet plate 13.

The hatched portion 22 in FIG.
3a and 14a are shown in mesh with each other.

In addition, the gear B14 is a motor 20 that can be rotated in forward and reverse directions.
It is provided so as to mesh with the gear A18 fixed to the output shaft 19 of.

Next, the operation of the paper feeding device of the present invention will be explained. however,
The same parts as the conventional one will be explained using FIG. 2. When starting paper feeding, first, the motor 20 is rotationally controlled, and the output shaft 19 is rotated clockwise.

Since gear A18 is fixed to output shaft 19, it rotates clockwise, and gear B14, which meshes with gear A18, rotates counterclockwise. Gear B14
At the start of rotation, the ratchet teeth 13a and 14a are separated from each other as shown in FIG. , gear B
14 slides in the direction of the ratchet plate 13, the ratchet teeth 13a and 14a mesh with each other, and the gear B14, the ratchet plate 13, the cylindrical member 11, and the paper feed roller 12 rotate counterclockwise as one, and the paper feed roller The top paper in the stacked cassette that comes into contact with the cassette is moved back.

Note that the frictional force between the inner peripheral surface of the gear B14 and the paper feed shaft 17 and the frictional force between the pin 16 and the groove 15 are
rotational load (for example, paper feed shaft 17 and paper feed shaft 1)
7), the gear B14 will not slide, the ratchet teeth 13a and 14a will not mesh, and the gear B14 will not slide.
This may cause a problem in which only the paper feed shaft 17 rotates and the cylindrical member 11 does not rotate. At this time,
Since the feed shaft 17 rotates counterclockwise, the one-way clutch 21 does not transmit rotational force. In order to prevent this inconvenience, a weak rotational load may be applied to the paper feed shaft 17 by some kind of braking means.

When the paper retreats to a position where the leading edge of the paper is disengaged from the leading edge pressing member 4, the output shaft 19
Start rotating counterclockwise. At the same time gear B14
starts rotating clockwise, and using the groove 15 as a guide, the gear B14 slides away from the ratchet plate 13.

A pin 16 is provided upright at the end of the groove 15 and the paper feed shaft 17
When the ratchet teeth 13a and 1 come into contact, the ratchet teeth 13a and 1 are already in contact with each other.
4a is a separated state (see FIG. 4b), and the paper feed shaft 17 and gear B14 begin to rotate clockwise as one unit.

Since the rotation direction of the paper feed shaft 17 is clockwise, the one-way bearing 21 transmits the rotational force, and the cylindrical member 11 and the paper feed roller 12 also rotate clockwise.

By rotating the paper feed roller 12 in the clockwise direction, the paper is fed to the front of the cassette, and the leading edge of the uppermost paper contacts the timing roller 6 pair, and the motor 20 stops when the paper is bent.

The timing roller 6 starts rotating at a predetermined timing of the copying machine, and pinches and conveys the paper whose leading edge is in contact with the timing roller 6.

As the paper advances, the cylindrical member 11 rotates clockwise due to friction between the paper and the paper feed roller 12, but this rotation is in a direction that does not transmit the rotational force of the one-way bearing 21. The paper feed shaft 17 does not rotate. In addition, the ratchet tooth 13 has already been
Since a and 14b are separated, the ratchet portion also does not apply a load to the rotation of the cylinder member 11.

In the above embodiment, the thrust in the axial direction of the gear B14 was obtained by the relationship between the groove 15 provided at an angle with respect to the paper feed shaft 17 and the pin 16, but other embodiments of the present invention may be used. As shown in FIG. 5, the system shown in FIG.

In the drive section, gear A23 and gear B24 are
This is a helical gear, and the thrust in the axial direction of the gear B24 is obtained by meshing the helical gears. Therefore, the groove 25 formed in the gear B24 may be parallel to the shaft 17, and as in the first embodiment, the groove 25 may be parallel to the shaft 17.
It may also be in an inclined direction.

Further, if a brake member that applies a weak rotational load to the gear B24 is provided, the sliding of the gear B24 becomes even more reliable. In the above embodiment, the drive in the backward direction of the paper was transmitted by the ratchet, but it goes without saying that the ratchet can be replaced with a friction plate as long as it has sufficient drive transmission. do not have.

[Effect of idea]

As explained in detail above, the paper feeding device of the present invention enables the forward and reverse rotation of the paper feeding roller to be controlled with a simple structure without the need for a complicated control circuit, thereby ensuring reliable conveyance of paper from the cassette. In addition, it is possible to provide a configuration in which an excessive load is not applied to the timing roller.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the drive unit of the paper feeder of the present invention, FIGS. 2a, b, and c are operating state diagrams of the conventional paper feeder, and FIG. 3 is the paper feeder of the present invention. 4a and 4b are sectional views showing the meshing and disengaging states of the ratchet plate and the ratchet teeth, and FIG. 5 is a cross-sectional view showing the second embodiment of the present invention. It is a side view of a gear. DESCRIPTION OF SYMBOLS 1...Paper feed roller, 2...Paper, 3...Push-up plate, 4...Tip pressing member, 5...Rear end regulating plate,
6... Timing roller, 11... Cylindrical member, 12
...Paper feed roller, 13...Ratchet plate, 13a
...Ratchet tooth, 14...Gear B, 14a...
Ratchet teeth, 15...Groove, 16...Pin, 17
... Paper feed shaft, 18 ... Gear A, 19 ... Output shaft,
20...Motor, 21...One-way bearing, 22...Shaded area, 23...Gear A, 24...
Gear B, 25...groove.

Claims (1)

[Claims for Utility Model Registration] (1) A paper feeder that abuts the uppermost sheet of the stacked sheets, and a presser member that abuts the leading edge of the uppermost sheet, the rear side of the sheet feeder. Paper feeding in which the uppermost sheet is moved backward by a conveying force to retract the leading edge of the uppermost sheet from the presser member, and then the sheet is advanced and fed by a forward conveying force of the sheet feeding means. In the apparatus, the drive source of the paper feeding means is a drive source capable of forward and reverse rotation, and the means for transmitting forward conveying force from the drive source to the paper feeding means transmits only the forward rotation drive of the drive source. a unidirectional rotation transmission means for transmitting a backward conveying force from the drive source to the paper feeding means, the means for transmitting backward conveying force from the drive source to the paper feeding means is a drive transmission means for transmitting only reverse driving of the drive source. . (2) The drive transmission means is provided on the rotation shaft of the paper feeding means, and includes a pair of contact/separation plates, at least one of which is movable in the axial direction of the rotation shaft depending on the rotation direction of the drive source. A paper feeding device according to claim 1 of the utility model registration claim, characterized in that: (3) The paper feeding device according to claim 2, wherein the movable contact/separation plate is moved by a guide means provided in a direction inclined with respect to the axial direction. (4) The movable contact/separation plate is moved by a thrust force in the axial direction generated by a combination of a driven helical gear provided on the contact/separation plate and a driving helical gear rotated by the drive source. A paper feeding device according to claim 2 of the utility model registration claim.