JPH0476566A - color image forming device - Google Patents

Abstract

PURPOSE:To simplify the constitution by providing an attaching / detaching mechanism which attaches/detaches developing device to/from an image carrier, and selecting a developing device by attachment. CONSTITUTION:When a driving motor 14 is driven, this rotational force is transmitted to a photosensitive drum 1, further transmitted to a developing sleeve 5Y through a gear 6, the photosensitive drum 1 and the developing sleeve 5Y are each rotated and driven at specified speed, and the electrostatic latent image formed on the photosensitive drum 1 is first developed by yellow toner and visualized. Next, the driving motor 12 of the attaching mechanism 13 is driven and a cam 11 is rotated in direction of an arrow, if its chamfer D is faced to a bearing 8M, the bearing 8M is moved in an inner direction of a diameter along a U shaped groove 10a by a spring 9M, and is abutted to the bottom of the U shaped groove 10a. Only a sleeve gear 6 bound to the developing sleeve 5M is engaged to a drum gear 2, and the electrostatic latent image formed on the photosensitive drum 1 is developed by magenta toner.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color image forming apparatus such as a color copying machine or a color printer that uses an electrophotographic method.

(Prior art) In an image forming apparatus, a photosensitive drum, which is an image carrier,
A charger, a cleaning device, a developing device, etc. are integrated into a process cartridge (hereinafter referred to as a cartridge), and by replacing the cartridge, each device can be replaced at the end of its service life, dirt can be cleaned, toner can be replenished, and waste toner can be disposed of. Conventionally, efforts have been made to simplify operations such as printing and the like, mainly for monochrome image forming apparatuses.

Recently, cartridges similar to those described above have also been used in full-color image forming apparatuses in which a plurality of developing devices each containing toner of a plurality of different colors are arranged around a photosensitive drum.

(Problem to be Solved by the Invention) However, in a conventional full-color image forming apparatus that uses a cartridge system, during the development of a specific color, that is, while driving a developing device containing toner of a specific color, , it was necessary to stop driving other developing devices. One possible solution to the above problem is to drive each developing device independently from the main body of the image forming apparatus, but this would complicate the connection of the drive between the cartridge and the main body and reduce accuracy. It is difficult to obtain high drive.

Another method would be to provide a driving mechanism for the developing device in each cartridge, but this method would increase the cost of the cartridge.

The present invention has been made in view of the above problems, and its purpose is to provide a color system that does not require a dedicated drive source for driving the developing 'tcM and allows the user to select a developing device with a simple configuration. An object of the present invention is to provide an image forming apparatus.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a process cartridge, which includes a plurality of developing devices having a plurality of different color developers arranged around an image bearing member, relative to the main body. In a color image forming apparatus that is configured to be detachable, an approach mechanism is provided for moving the developing device toward and away from the image carrier, and the developing device is moved toward and away from the image carrier by the approach and detachment mechanism. Its feature is that it is configured so that it can be selected.

(Function) According to the present invention, a desired developing device is selected by moving the developing device toward and away from the image carrier using the approaching and separating mechanism, and a driving force is applied to the selected developing device from the image carrier. The configuration of the driving force transmission device between the process cartridge and the main body of the image forming apparatus can be simplified, and a dedicated drive for independently driving the developing device can be configured. source is no longer needed.

Further, since the positional accuracy of the approaching/separating mechanism is not required to be particularly high, a developing device can be selected with a simple configuration.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a front view of the main parts of a cartridge that is attached to and removed from the main body of a color image forming apparatus according to the present invention, FIG. 2 is a cross-sectional view of the same, and FIG. It is a similar figure.

In the figure, reference numeral 1 denotes a photosensitive drum which is an image carrier, and a drum gear 2 is fixed to the end of the photosensitive drum 1. A drum shaft 3 of the photosensitive drum 1 is rotatably supported by a side plate 4 of the cartridge. There is.

Also, around the photosensitive drum l, there are four developing devices (yellow (Y), magenta (M), cyan (C), black (B)).
A developing device 5 (5Y, 5M, 5C) of each developing device is arranged.
, 58K) are each connected with a sleeve gear 6,
Shaft 7 of each developing sleeve 5 (7Y, 7M, 7C, 78K
) is rotatably supported by bearings 8 (8Y, 8M, 8C, 88K).

On the other hand, a positioning plate 10 is fixed to the side plate 4, and four U grooves 10a are formed on the outer circumference of the positioning plate 10, and the bearings 8 are mounted in each U910a in the radial direction (
It is slidably fitted in the normal direction of the photosensitive tram l.

Each bearing 8 has a spring 9 (9Y, 9M, 9C, 98
K) is biased radially inwardly. In addition, bearing 8
When the sleeve gear 6 comes into contact with the bottom of the U groove 10a,
The distance between the developing sleeve 5 and the photosensitive tram l is adjusted in advance with high precision so that it meshes with the tram gear 2 and the distance between the developing sleeve 5 and the photosensitive tram l is a predetermined value. Therefore, when the cartridge is not installed in the image forming apparatus main body, all the bearings 8 are in contact with the bottom of U910a of the positioning plate 10, and the three bearings 8 are in contact with the bottom of U910a of the positioning plate 10.
All the sleeve gears 6 mesh with the drum gear 2, and
All the developing sleeves 5 are located at a predetermined distance from the photosensitive drum l.

On the other hand, the main body of the image forming apparatus 1 is provided with drive motors 12 and 14, as shown in FIG. These drive motor 12 and cam 11 constitute a contact/separation mechanism 13 of the developing device. Incidentally, a notch is formed in a part of the outer circumference of the cam 11, as shown in FIG.

Further, a drive gear 15 that selectively meshes with the drum gear 2 is coupled to the output shaft 14a of the other drive motor 14.

When the cartridge is attached to the image forming apparatus main body from the direction of arrow A in FIG.
5, and the driving force can be transmitted from the drive motor 14 to the photosensitive tram 1. Further, in the example shown in FIG. 1, bearings 8M, 8C, and 8BK of the developing device, excluding bearing 8Y, which face the notch of the cam 11 are in contact with the outer periphery of the cam 11, and each U@lOa of the positioning plate lO is These bearings 8M, 8C, 88 are moved radially outward along the
The developing sleeves 5M, 5C, and 5BK supported by K are separated from the photosensitive drum 1 by a distance equal to or more than a predetermined value, and
The sleeve gear 6 connected to these is also separated from the tram gear 2.

From photosensitive drum l to developing sleeves 5M and 5C.

58 becomes impossible to transmit power to. Furthermore, cam 1
The outer diameter of sleeve 1 is sufficient as long as it is large enough to keep sleeve 5 sufficiently away from photosensitive tram 1, and its accuracy (photosensitive tram 1
A particularly high degree of accuracy is not required for coaxiality, etc.

On the other hand, the cam 11 does not engage with the bearing 8Y facing the notch of the cam 11, and since the bearing 8Y is farther from the notch, it is brought into contact with the bottom of U@10a by the spring 9Y, The developing sleeve 5Y supported by the bearing 8Y is arranged at a predetermined distance apart from the photosensitive drum 1, and only the sleeve gear 6 connected to the developing sleeve 5Y meshes with the tram gear 2, so that the developing sleeve 5Y is supported by the bearing 8Y. It becomes possible to transmit the driving force to the developing sleeve 5Y.

It should be noted that the depth of the notch of the cam 11 only needs to be such that the notch does not come into contact with the bearing 8Y, and high accuracy is not required.

Therefore, if the smell drive motor 14 is driven in the above state (the state shown in FIG. 1), the rotational power of this is transferred to the output shaft 14a
, is transmitted to the photosensitive drum l via the drive gear 15 and drum gear 2, and further via the sleeve gear 6 to the developing sleeve 5Y.
The photosensitive drum 1 and the developing sleeve 5Y are each rotated at predetermined speeds, and the electrostatic latent image formed on the photosensitive drum 1 is first developed with yellow toner and made into a visible image.

Next, drive the drive motor 12 of the contact/separation mechanism 13 to rotate the cam 11 by a predetermined angle in the direction of the arrow in FIG. The bearing 8M moves radially inward along UIIIOa by the spring 9M and comes into contact with the bottom of UIIIOa+7).

Then, in the same way as described above, only the developing sleeve 5M supported by the bearing 8M is located at a predetermined distance from the photosensitive drum l (a distance that allows development), and the developing sleeve 5M
Only the sleeve gear 6 connected to the drum gear 2 meshes with the drum gear 2, and the electrostatic latent image formed on the photosensitive drum 1 is developed with magenta toner.

Thereafter, in the same manner, the electrostatic latent image on the photosensitive drum 1 is sequentially developed with cyan toner and black toner to form a desired color image.

As described above, in this embodiment, a desired developing device is selected by moving the developing device toward and away from the photosensitive drum 1 using the approaching/separating mechanism 13, and the selected developing device is driven from the photosensitive drum 1. Since the developing device is driven by applying force, the structure of the driving force transmission device between the cartridge and the main body of the image forming apparatus is simplified, and a dedicated drive source for independently driving the developing device is not required. .

Further, since the positional accuracy of the cam 11 constituting the approach/separation mechanism 13 is not required to be particularly high, a developing device can be selected with a simple configuration.

According to the present invention, since the developing device in the drive release state is separated from the photosensitive drum, the present invention is applicable to a color image forming apparatus that employs any developing method including a developing method that brings the developing sleeve into contact with the photosensitive drum. Applicable to

Next, a modified embodiment of the present invention is shown in FIGS. 4 and 5.

In addition, FIG. 4 is a plan sectional view showing the main parts of the cartridge according to the modified example, and FIG. TS5 is a front view of the same, and in these figures, the same elements as shown in FIGS. A symbol is attached.

In this embodiment, the approaching/separating mechanism 13 is provided with an eccentric cam 16 (16Y) facing the developing sleeve 5 (5Y, 5M, 5C, 58K) of each developing device.

16M, 16C, 16BK).
Each eccentric cam 16 is independently driven by a drive motor 17 provided therein.

According to this embodiment, since the developing devices are selected individually, the developing devices may not be selected in the arranged order or there may be a need to shorten the switching time of the developing devices. However, it can be adequately addressed. The eccentric cam 16 is driven by a single drive motor and four clutches.
A method is conceivable in which each eccentric cam 16 is driven individually by F.

(Effects of the Invention) As is clear from the above description, according to the present invention, a process cartridge comprising a plurality of developing devices having a plurality of different color developers arranged around an image bearing member is attached to a main body. In a color image forming apparatus configured to be freely attachable and detachable, a detachable mechanism is provided for moving the developing device toward and away from the image carrier; Since the configuration allows selection, there is no need for a dedicated drive source for driving the developing device, and the advantage is obtained that the developing device can be selected with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a front view of the main parts of a cartridge that is attached to and removed from the main body of a color image forming apparatus according to the present invention, FIG. 2 is a cross-sectional view of the same, and FIG. Similar drawings, FIG. 4 is a plan sectional view showing essential parts of a cartridge according to a modified embodiment, and FIG. 5 is a front view thereof. 1--Photosensitive drum (image carrier), 2--Drum gear, 6--Sleeve gear, 11--Cam, 12゜14
．． 17-... Drive motor, 13... Approach/separation mechanism, 15
-... Drive gear, 16... Eccentric cam. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a color image forming apparatus in which a process cartridge including a plurality of developing devices each having a plurality of different color developers arranged around an image carrier is configured to be removably attached to the main body, the developing device is 1. A color image forming apparatus, comprising: a mechanism for moving the developing device toward and away from the image carrier; and a mechanism for selecting the developing device by moving the developing device toward and away from the image carrier. (2) The color image forming apparatus according to claim 1, wherein the approaching and separating mechanism includes a cam.