JPH0535041A - Color image forming device - Google Patents

Abstract

PURPOSE:To provide the color image forming device capable of miniaturizing a shutter, simplifying an opening and closing operation and reducing a storage space. CONSTITUTION:This color image forming device is made up so that a main cartridge B constituted of at least one photosensitive drum 1 and a sub-cartridge C constituted of a black developing device are loaded in the device main body in freely attachably and detachably. In the device, shutters 14 and 17 capable of opening and closing are respectively provided in a transfer exposure part 13 and developing exposure part 16 of the photosensitive drum 1 of the main cartridge B. Thus, since shutters 14 and 17 independently opening and closing the transfer exposure part 13 and the developing exposure part 16 of the photosensitive drum 1 are respectively provided in the main cartridge B, the shutter 14 and 17 can be miniaturized and the storing space of the shutter 14 and 17 in the device main body can be minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a color copying machine or a color printer adopting an electrophotographic system.

[0002]

2. Description of the Related Art Conventionally, at least a photosensitive drum or a developing unit which is an image carrier is unitized as a cartridge, and the cartridge is detachably attached to a main body of an image forming apparatus. In order to simplify the maintenance and the toner replenishing work, various proposals have been made and put to practical use to prevent contamination of the user's clothes, hands, etc. by the toner.

By the way, in such a cartridge, it is necessary to expose a position where the photosensitive drum faces a recording paper or a transfer belt as a transfer material (that is, a transfer area of the photosensitive drum), but the user replaces the cartridge. In order to prevent the photosensitive layer of the photosensitive drum from being exposed and exposed, or accidentally damaging the photosensitive layer, use a shutter that opens and closes manually or attach / detach the cartridge to / from the image forming apparatus body. It was common to provide a shutter that automatically opens and closes in conjunction with each other.

[0004]

However, in a color image forming apparatus for forming images of a plurality of colors such as yellow, magenta, cyan and black, at least a photosensitive drum and a developing unit are integrally formed (hereinafter,
When it is called a main cartridge), it is expected that the consumption amount of each color developer (hereinafter referred to as color toner) will be different, and in order to reduce the amount of unused toner as much as possible, especially color toner that is frequently used is used. It was necessary to use the developing unit having the above as another cartridge (hereinafter referred to as a sub cartridge). Therefore, the position where the photosensitive drum faces the developing unit of the sub cartridge (that is, the developing area of the photosensitive drum)
Also had to be exposed, so when the main cartridge was pulled out, this area also had to be covered with a shutter.

Therefore, as shown in FIG. 12, when the transfer area and the developing area are covered with a common shutter 46, the shutter 46 becomes very large, and the opening / closing operation of the shutter 46 becomes complicated. There is a problem that the image forming apparatus itself becomes large in size because a space for storing the opened shutter 46 is provided in the apparatus main body. Also, the strength of the shutter 46 needs to be increased more than ever before.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a color image forming apparatus capable of reducing the size of a shutter, simplifying the opening / closing operation, and reducing the storage space. To provide.

[0007]

In order to achieve the above object, the present invention provides a main cartridge including at least an image carrier and at least one sub cartridge including a developing unit with respect to an apparatus main body. In a color image forming apparatus which is detachably mounted, opening and closing of a transfer exposure portion where the image carrier of the main cartridge faces the transfer means and a development exposure portion where the image carrier faces the sub cartridge. The feature is that each possible shutter is provided.

[0008]

According to the present invention, since the main cartridge is provided with the shutters for independently opening and closing the transfer exposure portion and the development exposure portion of the image carrier, it is necessary to provide a complicated mechanism for opening and closing the shutter. Since the shutter itself is miniaturized, the space for storing the shutter in the apparatus body can be minimized.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, a schematic structure of a color image forming apparatus according to the present invention will be described with reference to FIG.

A main cartridge B and a sub cartridge C which are detachable from the image forming apparatus main body A are loaded in the image forming apparatus main body A, and the light source 3 is attached to the image forming apparatus main body A side from above. A fixing device 11, a paper discharge tray 12, a transfer drum 8, an external power source 9, a paper feed roller 7, and a recording paper cassette 6 are provided.

By the way, the main cartridge B includes a photosensitive drum 1 which is an image bearing member, a charger 2 arranged around the photosensitive drum 1, a yellow developing device 4Y, a magenta developing device 4M, a cyan developing device 4C and a cleaning device. Device 10
And the auxiliary cartridge C.
Is composed of a black developing device 4BK.

The photosensitive drum 1 in the main cartridge B is rotationally driven in the direction indicated by the arrow by a drive source (not shown), and the surface of the photosensitive drum 1 is uniformly charged by the charger 2. Next, when the electrostatic latent image corresponding to the yellow image is formed on the photosensitive drum 1 by the light source 3, the electrostatic latent image is developed as a yellow toner image by the yellow developing device 4Y. That is, when this is rotated while applying a bias voltage to the developing roller 5Y of the yellow developing device 4Y, the yellow toner adheres to the portion of the photosensitive drum 1 where the electrostatic latent image is formed, and so-called reversal development causes electrostatic discharge. The latent image is visualized as a yellow toner image.

On the other hand, the recording paper P in the recording cassette 6 is fed by the paper feed roller 7 and wound around the transfer drum 8. As a method of holding the recording paper P on the transfer drum 8, a known technique such as an electrostatic adsorption method or an air suction method can be used. In addition, a gripping mechanism such as grip claws may be provided on the transfer drum 8 as needed in order to hold the leading edge of the recording paper P.

Next, a voltage having a polarity opposite to the charging polarity of the photosensitive drum 1 is applied to the transfer drum 8 from the external power source 9 to transfer the yellow toner image on the photosensitive drum 1 onto the recording paper P, thereby recording paper. A visible yellow image is obtained on P.
The yellow toner that has not been transferred and remains on the photosensitive drum 1 is cleaned and removed by the cleaning device 10 including a blade, a fur brush, a magnetic brush, and the like.

The surface of the photosensitive drum 1 is uniformly charged by the charger 2 again, and magenta toner is attached to the surface of the photosensitive drum 1 by the magenta developing device 4M after the step of forming a magenta latent image. The magenta toner is transferred onto the recording paper P in an overlapping manner by the same action as described above. Similar operations are performed for the cyan developing device 4C and the black developing device 4BK, and the yellow toner, the magenta toner, the cyan toner, and the black toner are superimposed and transferred onto the recording paper P. After that, the recording paper P is peeled off from the transfer drum 8,
The toner on the recording paper P is fixed by the fixing device 11, and the recording paper P is discharged and stacked on the discharge tray 12.

The shutter structure of the main cartridge B will be described below with reference to FIGS.

As shown in FIG. 1, the main cartridge B has a first shutter 14 so as to cover a portion of the photosensitive drum 1 facing the transfer drum 8 (that is, a transfer exposed portion 13).
Is rotatably provided around the support shaft 15, and the second shutter 17 supports the support shaft 18 so as to cover a portion of the photosensitive drum 1 that faces the sub cartridge C (that is, the development exposed portion 16).
It is provided so as to be rotatable around. Then, at the free ends of the first and second shutters 14 and 17, a pin 20,
22 are respectively provided to project, and both shutters 14 and 1
7 is always biased in the closing direction by a spring or the like (not shown).

The main cartridge B and the sub cartridge C are loaded in the image forming apparatus main body A as follows. That is, the pin 2 provided on the shutters 14 and 17
0 and 22 are respectively engaged with the locking members 21 and 23 to open the shutters 14 and 17 as shown by the broken line in FIG. 1, and then the main cartridge B is provided in the image forming apparatus main body A (not shown). In order to place it on the main cartridge guide, the main cartridge B is inserted up to the solid line position in FIG. Then, at this stage, the sub cartridge C is inserted into the apparatus main body A from the direction of the arrow Y in FIG.

After that, the cover 19 of the main body A of the image forming apparatus is used.
When is closed, the main cartridge guide (not shown) moves downward in conjunction with this operation, and the main cartridge B is guided by the main cartridge guide and moves to a predetermined position shown in FIG. 2 and is fixed.

With the above arrangement, the shutter 1
Since it is not necessary to provide a complicated mechanism for opening and closing the shutters 4 and 17, and the shutters 14 and 17 themselves can be made small, the space for storing the shutters 14 and 17 in the apparatus main body A can be minimized.

The image forming apparatus shown in the present embodiment is a color image forming apparatus which adopts a so-called frame sequential system in which each color toner is transferred onto a recording paper, but an endless belt-shaped transfer member is used. A so-called intermediate transfer body method in which each color toner is transferred once and then all color toners are collectively transferred to the recording paper, or each color toner is collectively developed on the photosensitive drum, and then all color toners are collectively transferred to the recording paper. Of course, the present invention can be applied to a color image forming apparatus that employs a so-called batch development method.

Further, although the number of the sub cartridge C is one in this embodiment, a plurality of sub cartridges C and C'are used as shown in FIG. It is also possible to provide the shutters 14, 17, and 24.

Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7.
Shown in.

This embodiment is an example in which the opening / closing operation of the shutters 25 and 28 is automatically performed in association with the attachment / detachment operation of the main cartridge B.

As shown in the figure, the main cartridge B is provided with a first shutter 25 and a second shutter 28 rotatably around support shafts 26 and 29, respectively, and both shutters 25 and 28 are not shown. Is always urged in the closing direction by a spring or the like. The shutters 25 and 28 are provided with the first and second cam guides 3 provided on the apparatus main body A side.
First and second cams 27 and 3 to be engaged with the first and second cams 32 and 3, respectively.
0 is provided for each.

Next, the procedure for loading the main cartridge B and the sub cartridge C into the main body A of the image forming apparatus will be described.

Similar to the first embodiment, first, in order to mount the main cartridge B on the main cartridge guide (not shown), the main cartridge B is inserted up to the solid line position shown in FIG. Then, at this stage, the sub cartridge C is inserted into the apparatus main body A from the direction of the arrow Y in FIG.

Next, the cover 19 of the apparatus main body A shown in FIG.
When is closed, the main cartridge guide moves downward in conjunction with this operation, and the main cartridge B is fixed at the position shown in FIG. At this time, the first cam 27 provided on the first shutter 25 is engaged with the first cam guide 31 provided on the apparatus main assembly A side, and the second cam 30 provided on the second shutter 28 is installed on the apparatus main assembly A. Since the second cam guide 32 provided on the side is engaged, the shutters 25 and 28 are automatically opened.

8 and 9 show the third embodiment of the present invention. In this embodiment, when the second shutter 33 is opened, the shutter 33 is housed between the sub cartridge C and the transfer drum 8. This is an example.

The mounting / dismounting operation of the main cartridge B and the sub cartridge C is the same as that of the above-described embodiment, but the second shutter 33 for covering the portion of the photosensitive drum 1 facing the sub cartridge C (that is, the developing and exposing portion 16) is provided. The support shaft 34 is rotatably pivotally mounted, and is constantly urged in the closing direction by a spring or the like (not shown).

When the main cartridge B is moved and fixed from the position shown in FIG. 8 to the position shown in FIG. 9, the second cam 35 provided on the second shutter 33 is attached to the main assembly A of the apparatus. Since the second shutter 33 is engaged with the provided second cam guide 36, the second shutter 33 is opened, which is housed between the transfer drum 8 and the sub cartridge C as shown in FIG. As a result, it is possible to prevent the transfer drum 8, the recording paper, and the like from being contaminated due to the scattering of toner that occurs during development.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the second shutter 37 is opened by engaging the second cam 44 provided on the shutter 37 and the second cam guide 45 provided on the sub cartridge C. is there.

The mounting / dismounting operation of the main cartridge B and the sub cartridge C is the same as that of the above-mentioned embodiment, but the second shutter 37 for covering the portion of the photosensitive drum 1 facing the sub cartridge C (that is, the developing and exposing portion 16) is provided. , A link member 4 pivotally attached to the main cartridge B by support shafts 42 and 43, respectively.
It is supported by 0, 41, which is always urged in the closing direction by a spring or the like (not shown).

Then, when the main cartridge B is moved from the position shown in FIG. 10 to the position shown in FIG. 11 and fixed, the second cam 44 provided on the second shutter 37.
Engages with the second cam guide 45 provided on the sub cartridge C, and the second shutter 37 is automatically opened as shown in FIG.

Here, when the sub cartridge C is not inserted in the main body of the image forming apparatus, the main cartridge 37
Since the second shutter 37 is not opened, there is no fear of toner spilling from the main cartridge B even when developing with the sub cartridge C not inside the apparatus main body, and the inside of the machine is contaminated with toner. There is no.

[0038]

As is apparent from the above description, according to the present invention, the main cartridge including at least the image carrier and the at least one sub cartridge including the developing unit are provided with respect to the apparatus main body. In a color image forming apparatus which is detachably mounted, opening and closing of a transfer exposure portion where the image carrier of the main cartridge faces the transfer means and a development exposure portion where the image carrier faces the sub cartridge. Since each possible shutter is provided, it is possible to obtain an effect that the shutter can be downsized, the opening / closing operation can be simplified, and the storage space can be reduced.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of a shutter when a cartridge is mounted according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the shutter when the cartridge according to the first embodiment of the present invention is mounted.

FIG. 3 is a vertical sectional view showing a cartridge loading operation in the color image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a vertical sectional view of a color image forming apparatus according to the present invention.

FIG. 5 is a vertical sectional view of a color image forming apparatus showing a modification of the first embodiment of the present invention.

FIG. 6 is an operation explanatory view of a shutter when a cartridge is mounted according to a second embodiment of the present invention.

FIG. 7 is an explanatory view of the operation of the shutter when the cartridge according to the second embodiment of the present invention is mounted.

FIG. 8 is an operation explanatory view of the shutter when the cartridge is mounted according to the third embodiment of the present invention.

FIG. 9 is an explanatory view of the operation of the shutter when the cartridge is mounted showing the third embodiment of the present invention.

FIG. 10 is an explanatory view of the operation of the shutter when the cartridge according to the fourth embodiment of the present invention is mounted.

FIG. 11 is an explanatory view of the operation of the shutter when the cartridge according to the fourth embodiment of the present invention is mounted.

FIG. 12 is a diagram showing a shutter structure of a conventional color image forming apparatus.

[Explanation of symbols]

A Image forming apparatus body B main cartridge C sub cartridge 1 Photosensitive drum (image carrier) 4Y yellow developing device 4M magenta developing device 4C cyan developing device 4BK black developing device 8 Transfer drum (recording paper transfer means) 13 Transfer exposed part 14 First shutter 16 Development exposed part 17 Second shutter 25 First shutter 28 Second shutter 33 Second shutter 37 Second shutter 45 Cam guide (engagement member)

Claims (4)

[Claims] 1. A color image forming apparatus in which a main cartridge including at least an image carrier and at least one sub cartridge including a developing unit are detachably mounted in an apparatus main body. A color image, wherein an openable and closable shutter is provided in each of a transfer exposure portion where the image carrier of the main cartridge faces the transfer means and a development exposure portion where the image carrier faces the sub cartridge. Forming equipment. 2. The color image forming apparatus according to claim 1, wherein at least one of the shutters is automatically opened / closed in association with an attaching / detaching operation of the main cartridge. 3. The color image forming apparatus according to claim 1, wherein at least one of the shutters is housed between the sub cartridge and the transfer unit in the open position. 4. A shutter provided at a developing exposed portion of the image carrier is opened and closed by engaging with an engaging member of the sub cartridge in association with an attaching / detaching operation of the main cartridge. The color image forming apparatus according to claim 1.