JPH0273268A - image forming device - Google Patents

Abstract

PURPOSE:To facilitate the switching of a developing position and a non- developing position without using a private motor by providing the developing devices for respective colors so that they can be moved in a horizontal direction and using a developing roller driving motor also for moving them between the developing position and the non-developing position. CONSTITUTION:The developing devices for respective colors 3-6 are provided on a guide rail 12 in a frame body 11 so that they can be moved in the horizontal direction by allowing a guide roller 13 to be rotated. On the other hand, the developing roller driving motor 21 is fixed to a plate 15 on the back side and the power thereof is propagated to developing rollers 9 through gears 22-25. In the case that the motor 21 of the developing device 4 is rotated anticlockwise under this constitution, for example, though the roller 9 is rotated, the propagating power makes the developing device 4 abut on a photosensitive body 1 because the load of the motor 21 is large. Then, the roller 9 is rotated after that. When the motor 21 is rotated clockwise, the developing device 4 returns to the non-developing position and the other developing devices also do the same.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus in which a developing device is switched between a developing state and a non-developing state.

[Conventional technology]

Image forming apparatus 1 of a type in which a plurality of developing devices are placed opposite to a latent image carrier 1 For example, in an electronic copying machine, printer, facsimile, etc., for any selected developing device that is performing development, other developing devices are The developer roller in the developing device is separated from the latent image carrier.

This prevents the toner image developed by the upstream developing device from being disturbed by the developer carried on the developing roller of the downstream developing device, and T! 1. This is to prevent developers of different colors from mixing between image devices.

As a known example of operating the developing device itself,
Techniques such as those disclosed in Japanese Patent Application No. 07 and Japanese Patent Application Laid-open No. 18332/1983 have been proposed.

Also, as a known example of moving the developing roller, there is
A technique such as that disclosed in Japanese Patent No. 18332 has been proposed.

[Problem to be solved by the invention]

In the former example, the structure itself is complicated because a spring is required to separate the developing device, and a separate specialized movement means is required to move the developing device toward and away. Furthermore, in the latter example, since the developing roller itself moves, it is difficult to determine how to transmit the driving force to the developing roller.

It is an object of the present invention to provide fl[! To provide an image forming apparatus that can reliably switch between a developing state and a non-developing state with a simple configuration.

[Means to solve the problem]

In order to achieve the above object, the present invention relates to an image forming apparatus according to the present invention, including a latent image carrier that forms an electrostatic latent image;
A plurality of developing devices arranged opposite to the latent image carrier, a developing roller provided in each developing device for developing the electrostatic latent image, and a developing position where each of the plurality of developing devices performs the development. and a non-developing position where no development is performed, and a developing roller rotation that performs both the moving operation of the developing device to both positions and the rotational beating of the developing roller. The device is characterized by comprising a drive mechanism.

[Effect]

When the developing roller rotation and sleep mechanism operates, the five developing devices are switched to the developing position when developing, and to the non-developing position when not developing.

〔Example〕

Examples will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a belt-shaped photoreceptor, which is an example of a latent image carrier. An image is formed.

The photoreceptor 1 includes a plurality of developing devices 3, four in the illustrated example.
4, 5, and 6 are arranged facing each other, each of which develops an electrostatic latent image as a toner image using a developer of a different color every time an electrostatic latent image is formed. A transfer belt 7 is disposed at the lower end of the photoreceptor 1 so as to be perpendicular thereto, and a transfer paper S is supported and conveyed on this belt.

A transfer paper S is sent to the transfer belt 7, and as the transfer belt 7 rotates forward and backward, the transfer paper reciprocates on the belt. For example, when moving forward in the direction of arrow a in the figure, the toner image on the photoreceptor is The image is transferred onto a transfer paper S by a transfer charger 8. Then, toner images of different colors are sequentially transferred onto a transfer paper in an overlapping manner, and a predetermined color image is obtained on the transfer paper.

Each developing device is configured in exactly the same way, and each of them includes:
A developing roller 9 is provided for developing the electrostatic latent image mentioned above. Each developing device equipped with such a developing roller is provided within the frame 11.

The frame 11 is movable between a development position where development is performed and a non-development position where development is not performed.

1, 2, and 3, a guide rail 12 is fixed to the frame 11, and each developing device is provided with guided rollers 13, 14, which are rolled along the guide rail 12. The developing device can be moved to both of the above positions by rolling the guided rollers 13 and 14 that sandwich the developing device 4. 13.14 and guide rail 1
Although only 2 is shown, these are similarly provided in other developing devices 3, 5, and 6, and the same applies to each element described later. Further, each developing device can be inserted into and removed from the frame 11 in a direction perpendicular to the photoreceptor 1 (lateral direction). Incidentally, guided rollers 13 and 14 are also provided on the opposite side of each developing device shown in FIG. 3, and similarly roll on guide rails.

Here, the development position is a position where development with a developer is possible, and in one example, the development roller 9 is located on the photoreceptor 1.
This is the position indicated by 9' that is slightly in contact with the surface, and in this state, the above-mentioned development is performed. On the other hand, the non-development position is a solid line position away from the photoreceptor 1 where no development is performed, and the developer on the developing roller 9 does not come into contact with the photoreceptor 1 at this position.

While each developing device is movable laterally relative to the frame 11, the frame 11 also has guide rails 16 fixed to a back side plate 15 and a front side plate (not shown) of the device main body, respectively. On the other hand, guided rollers 17, 18, and 19 mounted on each outer wall surface of the frame 11 are able to move freely in the vertical direction by rolling, and can be inserted and removed in this direction. There is. That is, the frame body 11, together with the developing device, can be inserted into and removed from the main body of the device.

A motor 21 is fixed to the back side plate 15, and this rotation is
Motor gear 22. A gear 23 provided on the side of the frame 11.
24 and a developing roller gear 25 provided on the developing device side, the image is transmitted to the developing roller 9 (see FIG. 4). In this example, the motor 21 is also used for each developing device i! 3
, 4, 5, and 6, one motor 21 is provided, and a clutch is interposed between this motor and the developing roller 9 of each developing device to connect and release the motor 21. As described later, it is also possible to rotate the developing roller 9 or move the developing device.2 Now, if the developing device 4 is selected as necessary, the motor 21 is rotated counterclockwise (the first The gear 23 and the gear 24 integrated therewith are rotated clockwise (in the direction of the arrow) via the motor gear 22.

This gear 24 transmits rotation to a developing roller gear 25 that is integrated with the developing roller 9, and tries to rotate the developing roller 9. However, when the developing device 4 is not performing development, the developing roller 9 is connected to the photoreceptor 1. When the rotational force is transmitted from the gear 24 to the gear 25, the load for rotating the developing roller 9 is greater than the load for moving the developing device itself, for example. , has become extremely large due to the influence of the rotational load of the agent stirring member (not shown) in the developing device, which is another driven body, so at the initial stage, this force causes the developing device 4 to move linearly. An angle 26 that acts as a force and is provided integrally with the developing device
The developing device itself is rotated δ until it abuts the left end of the notch 27a of the stopper member 27 provided on the side of the frame 11.
move only.

Here, a rotational force is generated on the developing roller 9, and the developing roller 9 rotates in contact with the photoreceptor 1 at a position 9', thereby visualizing the electrostatic latent image on the photoreceptor.

Here, when the development of the desired area is completed, the motor 21 is now reversed clockwise (opposite to the solid line direction), and the developing device is moved in the same manner.

It is moved back to the home position, which is a non-developing position.

Even when the developing device moves to either the developing position or the non-developing position, gear 25 and gear 24 remain in mesh with each other, but since the amount of linear movement δ of the developing device is small, gear 25
The amount of change in the distance between the shafts and the gear 24 is minute and does not interfere with power transmission.

For example, the number of teeth of gears 25 and 24 is 20. Module 1. When δ is 3.5 m, the amount of change in the center distance is 0.
The length is 3m, which poses no practical problem.

As a result, it is possible to smoothly switch between the developing position 9 and the non-developing position of the developing device, and at the same time, the developing roller can be driven without any trouble.

In this way, the developing roller rotation drive mechanism is as follows.

Since the moving operation for changing the position of the developing device and the rotational driving of the developing roller are performed, there is no need for a dedicated drive means for changing the position.
Since there is no need for a spring or the like to separate the developing devices, this helps to further simplify the configuration.

By the way, although this differs depending on various conditions, for example, when the speed of the photoreceptor 1 is about L 2 OffI/sec, the peripheral speed of the developing roller 9 is 300 m.
/see is necessary. In this case, when the motor 21 starts rotating, the developing device moves by δ=3.51, but 0
．． This means that only a little less than 0.02 seconds is required, and this value causes considerable instantaneous load fluctuations on the photoreceptor 1.

If such a load fluctuation rate is large, the speed of the photoreceptor 1 will fluctuate, resulting in image shift of the image on the transfer paper. In order to prevent this, it is necessary to increase the moving time of the developing device by at least 10 times.

In view of this, a variable speed motor is used for the motor 21, and the speed is adjusted such that the developing device rotates at a low speed while moving to the developing position, rotates at a high speed during development, and rotates at a low speed in reverse during the return process. If you switch the lamp load (
(applying the load gradually), it is possible to effectively prevent the occurrence of image shift.

In FIG. 1, a stopper member 27 is also provided for each developing device to position each developing device, and
It also achieves the function of locking each developing device to the frame 11, and when taking out the developing device from the frame 11,
By simply removing the stopper member 27, each developing device can be pulled out laterally very easily. That is, it is possible to improve the assemblability and maintainability of this type of developing device. Furthermore, each developing device has the same configuration, and cost reduction of the device can be expected due to such commonization.

Also, by rotating the eccentric pin 28 that supports the stopper member 27, the stopper member 27 can be rotated.

Adjust the horizontal position in FIG.
The amount of contact with the photoreceptor 1 can be adjusted.

Further, when it is desired to widen the right side of the photoreceptor 1 in the figure during maintenance and inspection, it is sufficient to remove the frame 11 itself. That is, it is possible to save the effort of taking out the developing devices one by one from the main body of the apparatus.

Note that, as shown in FIG. 4, the frame 11 is connected to the developing device 23.
(4, 5, 6) When taking everything out upwards.

The gear 23 separates from the motor gear 22 and the meshing state is released. When the developing device is taken out laterally from the removed frame 11, the gear 25 on the developing device side separates from the gear 24 on the frame 11 side. Then, the engaged state is released.

FIG. 5 shows another embodiment of the present invention, in which a frame body designated by reference numeral 31 is provided with a guide rail 32, and with respect to this guide rail 32, a guided roller 33 is provided on the developing device side.
By rolling 34, the developing device can be moved laterally as in the previous embodiment (see FIG. 6).

This embodiment is characterized in that the spur gear (including helical gear and screw gear) coupling of the previous embodiments is replaced with a worm gear coupling.

As shown in FIGS. 6 and 7, the motor gear 35 is driven by a motor (not shown), and this rotation is caused by the rotation of the frame 31.
Idle gear 36, gear 37. It is transmitted to the developing roller 9 via a worm 38 and a worm gear 39 that are integrated with this. In addition, the gear 37 and the worm 38
is directly connected to a shaft 40, and this shaft 40 is rotatably supported by a shaft support member 41 fixed to the frame 31.

This embodiment utilizes the thrust force in the axial direction of the worm as the force for moving the developing device toward and away from the developing device.1 It is functionally similar to the above-mentioned embodiment, but the rotation of the motor can be easily decelerated. Therefore, 1 it is possible to eliminate the need for a speed reduction device such as that used in a normal developing device 6. Note that when removing the frame 31 shown in FIG. When the idle gear 36 shown in FIG. 7 is separated from the motor gear 35 and the meshing state thereof is released, and the developing device is taken out laterally from the frame 31 that has been taken out, the worm gear 39 on the developing device side shown in FIG. When it separates from the worm 38, the meshing state is released.

〔Effect of the invention〕

According to the present invention, the development position of the development device,
It is possible to provide an image forming apparatus that can reliably and easily switch to a non-developing position.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of an embodiment of the present invention, FIG. 2 is a partial plan view of the embodiment, FIG. 3 is a partial side view of the embodiment, and FIG. 4 is a developing roller rotation drive mechanism of the embodiment. A perspective view of
FIG. 5 is a partially cutaway front view of an embodiment of the present invention, FIG. 6 is a partial side view of another embodiment of the invention, and FIG. 7 is a perspective view of a developing roller rotation drive mechanism of another embodiment of the invention. 1... Belt-shaped photoreceptor as a latent image carrier 3.4, 5
．． 6...Developing device 9...Developing port-ra surprise 4 Haze shape 7 Haze

Claims (1)

[Claims] a latent image carrier that forms an electrostatic latent image; a plurality of developing devices disposed opposite to the latent image carrier; a developing roller provided in each developing device for developing the electrostatic latent image; a frame body that supports each of the developing devices movably between a developing position where the development is performed and a non-development position where the development is not performed;
An image forming apparatus comprising: a developing roller rotation drive mechanism that moves the developing device to both positions and rotates the developing roller.