JP2000019844A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device which inhibits a developing roller from being caused to rotate in the direction reverse to that of normal rotation when a developing unit is moved close to a photoreceptor drum or apart from it, and which prevents toner from being caused to fall accompanying reverse rotation of the developing roller. SOLUTION: The developing unit 13 equipped with the developing roller 14 is disposed so as to be movable to a close position P1 or a separate position P2 in relation to the photoreceptor drum 12. When the developing unit 13 is moved and disposed in the close position P1, the developing roller 14 is actuated and connected to a drive motor 15 via a gear train, 16 and 20. To the output gear 19 of the gear train, 16 and 20, a one-way clutch 25 is interposingly attached for preventing reverse rotation of the developing roller 14 during the movement of the developing unit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing device in an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art As a conventional developing device of this type, for example, a developing device having a structure as shown in FIG. 4 is known. In this conventional configuration, a developing unit 31 having a developing roller 32 is movably disposed between a position P1 close to the photosensitive drum 33 and a position P2 away from the photosensitive drum 33. Then, with the developing unit 31 moved to the separated position P2, the developing unit 31 is detached from the main body.

On the other hand, a drive motor 34 for driving the developing roller 32 of the developing unit 31 is provided on the main body side. Then, in a state where the developing unit 31 is moved and arranged at the close position P1, the developing roller 32 is moved by the drive motor 34 through the main body and the gear train 35 arranged on the developing unit 31 in a direction indicated by an arrow in FIG. It is driven to rotate. When the developing unit 31 is moved to the separated position P2, as shown in FIG. 5, the input gear 35a on the developing unit 31 side in the gear train 35 is separated from the output gear 35b on the main body side.

[0004]

However, in this conventional developing device, as shown in FIG. 5, when the developing unit 31 is moved from the separation position P2 to the close position P1, the drive motor 34 is stopped. The input gear 35a meshes with the output gear 35b, and the developing roller 32 is caused to rotate in a direction opposite to the normal rotation. Further, the developing unit 3
In a configuration in which the number of idle gears 35c arranged on one side is different, when the developing unit 31 is moved from the close position P1 to the separated position P2, the developing roller 32 may be rotated in a direction opposite to the normal direction. is there.

As described above, when the developing roller 32 is rotated in the reverse direction, there is a problem that the toner accumulated in the jaw 31a of the developing unit 31 is scraped out and the toner drops. In addition, as shown in FIG.
When the roller 2 is rotated in the normal rotation direction, toner does not drop due to the polar position.

The present invention has been made by paying attention to such problems existing in the conventional technology. The purpose is to prevent the developing roller from rotating in the opposite direction to the normal rotation when the developing unit is moved toward and away from the photosensitive drum. An object of the present invention is to provide a developing device that can prevent the possibility of toner dropping.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a developing unit having a developing roller is movably arranged at a position close to and away from a photosensitive drum. A developing roller is operatively connected to a drive source via a gear train in a state where the developing unit is moved and arranged in the proximity position. A one-way clutch is provided to prevent the rollers from being reversed.

According to a second aspect of the present invention, in the developing device according to the first aspect, the one-way clutch is interposed in a gear train from a drive source on a main body side to an output gear.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. As shown in FIGS. 1 and 2, a photosensitive drum 12 is provided in a main body 11 of an image forming apparatus such as a copying machine, a printer, and a facsimile. In the main body 11, a developing unit 13 is movably disposed between a position P1 close to the photosensitive drum 12 and a position P2 separated from the photosensitive drum 12, and a developing roller 14 is rotatably supported therein. Then, as shown in FIG. 1, in a state where the developing unit 13 is moved and arranged at the close position P1, the developing roller 14 is opposed to the outer peripheral surface of the photosensitive drum 12 at a predetermined interval. Further, the developing unit 13
Can be attached to and detached from the main body 11 in a state where is moved to the separated position P2.

In the main body 11, a drive motor 15 as a drive source is provided. Transmission gear 1 on main body 11 side
A body-side gear train 16 composed of 7, 18 and an output gear 19 is arranged and operatively connected to a drive motor 15. On the developing unit 13 side, the input gear 21 and the idle gear 2
Unit-side gear train 2 including drive gears 2 and 23 and drive gear 24
0 is arranged.

As shown in FIG. 1, when the developing unit 13 is moved to the close position P1, the input gear 21 of the unit-side gear train 20 meshes with the output gear 19 of the main-body gear train 16, and The roller 14 is a double gear train 20,
The drive motor 15 is operatively connected to the drive motor 15 through the drive motor 16. Also,
As shown in FIG. 3, when the developing unit 13 is moved to the separated position P2, the input gear 21
And the operative connection between the developing roller 14 and the drive motor 15 is released.

In the gear train 16 on the main body side, a one-way clutch 25 is mounted on the output gear 19.
When the developing unit 13 is moved from the separated position P2 to the close position P1, the one-way clutch 25 absorbs the rotational force generated by the engagement between the input gear 21 and the output gear 19. .

Next, the operation of the developing device configured as described above will be described. In the state shown in FIG. 1, the developing unit 13 is arranged at a position P1 close to the photosensitive drum 12, the developing roller 14 is arranged facing the outer peripheral surface of the photosensitive drum 12 at a predetermined interval, and the unit-side gear train is provided. 20 is the output gear 1 of the main body side gear train 16
9 is engaged. In this state, when the drive motor 15 is rotated, the main gear train 16 and the unit gear train 2 are rotated.
The developing roller 14 is rotated in the direction of the arrow in FIG. Thus, the toner in the developing unit 13 is supplied to the electrostatic latent image on the photosensitive drum 12, and the latent image is visualized.

On the other hand, when the maintenance and inspection of the developing unit 13 are performed, the developing unit 13 is moved from the close position P1 shown by the solid line in FIG. 1 to the separated position P2 shown by the two-dot chain line while the drive motor 15 is stopped. Then, the unit side gear train 2
The 0 input gear 21 is disengaged from the output gear 19 of the main body gear train 16. By removing the developing unit 13 from the main body 11 in this state, maintenance and inspection can be performed.

After the maintenance and inspection of the developing unit 13, the developing unit 13 is mounted at the separated position P2 of the main body 11. Thereafter, when the developing unit 13 is moved from the separation position P2 to the close position P1, the input gear 21
9 and the developing roller 14 is in contact with the two gear trains 16 and 20.
Is operatively connected to the drive motor 15 on the main body 11 side.

As described above, when the developing unit 13 is moved from the separation position P2 to the close position P1, the input gear 21 and the output gear 19 mesh with each other, so that the two gears 21,
A rotational force in the opposite direction is generated during the period 19. However,
Since the one-way clutch 25 is incorporated in the output gear 19, the rotational force generated between the two gears 21 and 19 is absorbed by the one-way clutch 25, and only the output gear 19 idles in the direction of the arrow in FIG. .

Therefore, the rotational force generated between the two gears 21 and 19 is transmitted through the unit side gear train 20 to the developing roller 14.
And the developing roller 14 is not rotated in a direction opposite to the normal rotation. Therefore, there is no possibility that the toner accumulated in the jaw 13a of the developing unit 13 is scraped out due to the reverse rotation of the developing roller 14, and the toner drops.

The effects exerted by the above embodiment will be described below. In the developing device of this embodiment, the developing roller 1
The developing unit 13 provided with the developing unit 4 is movably disposed between a position P1 close to the photosensitive drum 12 and a position P2 away from the photosensitive drum 12. The developing roller 14 is operatively connected to a driving motor 15 as a driving source via gear trains 16 and 20 in a state where the developing unit 13 is moved and arranged at the proximity position P1. A one-way clutch 25 is interposed in the gear trains 16 and 20 to prevent the developing roller 14 from rotating backward when the developing unit 13 moves.

Therefore, when the developing unit 13 is moved toward and away from the photosensitive drum 12, it is possible to prevent the developing roller 14 from rotating in a direction opposite to the normal rotation. Accordingly, it is possible to prevent the possibility that the toner accumulated in the jaw 13a of the developing unit 13 is scraped out due to the reverse rotation of the developing roller 14 and the toner drops.

In the developing device of this embodiment,
The one-way clutch 25 is connected to the drive motor 1 on the main body 11 side.
It is interposed in a gear train 16 from 5 to an output gear 19. Therefore, the developing unit 13 can be made smaller and lighter than when the one-way clutch 25 is interposed in the gear train 20 on the developing unit 13 side.

In the developing device of this embodiment,
The one-way clutch 25 is mounted on the output gear 19 in the gear train 16 on the main body 11 side. Therefore, the space and strength for the one-way clutch 25 can be secured, and the developing roller 14 can be more reliably prevented from being reversely rotated when the developing unit 13 moves toward and away from the developing unit 13.

This embodiment can be modified and embodied as follows. The one-way clutch 25 is provided inside other gears such as the transmission gears 17 and 18 in the main body gear train 16.

The one-way clutch 25 is provided in both the main gear train 16 and the unit gear train 20. With this configuration, it is possible to more reliably prevent the developing roller 14 from rotating in the reverse direction when the developing unit 13 moves toward and away from the developing unit 13.

An input gear 21 and idle gears 22 and 2
3 and a drive gear 24,
Be composed of two gear trains or four or more gear trains. Further, a technical idea grasped from the embodiment will be described below.

The developing device according to claim 1, wherein the one-way clutch is interposed in a gear train from the input gear on the developing unit side to the developing roller. With this configuration, it is possible to reliably prevent the developing roller from being reversely rotated when the developing unit is moved toward and away from the developing unit.

The developing device according to claim 2, wherein the one-way clutch is provided inside an output gear in a gear train on the main body side. With this configuration, it is possible to secure a space and strength for the one-way clutch, and it is possible to more reliably prevent the developing roller from being reversely rotated when the developing unit is moved toward and away from the developing unit.

The developing device according to claim 2, wherein the one-way clutch is further provided in a gear train from the input gear on the developing unit side to the developing roller. With this configuration, it is possible to more reliably prevent the developing roller from being reversely rotated when the developing unit is moved toward and away from the developing unit.

[0028]

The present invention is configured as described above, and has the following effects. According to the developing device of the first aspect, when the developing unit is moved toward and away from the photosensitive drum, it is possible to prevent the developing roller from rotating in the opposite direction to the normal rotation. Thus, it is possible to prevent the possibility that toner drops due to the reverse rotation of the developing roller.

According to the developing device of the second aspect, in addition to the effects of the first aspect, a space and strength for the one-way clutch can be ensured.
The developing unit can be small and lightweight.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing an embodiment of a developing device of the present invention.

FIG. 2 is a plan view of a main part of the developing device.

FIG. 3 is a partially broken front view showing a moving state of the developing device.

FIG. 4 is a partially broken front view showing a conventional developing device.

FIG. 5 is a partially broken front view showing a moving state of the developing device.

[Explanation of symbols]

11: body, 12: photosensitive drum, 13: developing unit,
13a: jaw, 14: developing roller, 15: drive motor as a drive source, 16: gear train on the main body side, 19: output gear,
20: gear train on the unit side, 21: input gear, 25: one-way clutch, P1: proximity position, P2: separation position.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiko Kurosu F-term (reference) 2H077 BA03 BA09 GA01 within 1-2-2 Tamazo, Chuo-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. A developing unit having a developing roller is movably disposed at a position close to and away from a photosensitive drum, and the developing unit is moved to a position close to the photosensitive drum.
In the developing device, the developing roller is operatively connected to a drive source via a gear train. In the gear train, a one-way clutch for preventing the developing roller from being reversely rotated when the developing unit moves is provided. Mounted developing device. 2. The developing device according to claim 1, wherein said one-way clutch is interposed in a gear train from a drive source on a main body side to an output gear.