JPH0962099A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an electrostatic latent image carrier and a developing roller into a non-pressure state when a process unit is not used for a long period, and to unnecessitate the control of a member such as a spacer for separating both. SOLUTION: In a state that the process unit provided with a photoreceptor drum 21 and a developing device for making toner stuck on the photoreceptor drum with use of a developing roller 23 is detached from the device main body, the photoreceptor drum and the developing roller are kept in the non-pressure state. Moreover, after a positioning member 29 is disposed on the device main body, a rotary shaft 21a of the photoreceptor drum is inserted in a first guide opening 27 of the positioning member, and the rotary shaft 23a of the developing roller is inserted in the second guide opening 28, and when the process unit is attached to the device main body, the developing roller is held in press contact with the photoreceptor drum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image by electrophotography.

[0002]

2. Description of the Related Art In an image forming apparatus of this type, as shown in FIG. 6, a photosensitive drum 2 which is an electrostatic latent image holding member and a developing roller 3 of a developing device are rotatably attached to a frame 1 as a process unit. It is known that the developing roller 3 is integrated and the developing roller 3 is constantly in pressure contact with the photosensitive drum 2. That is, the distance between the center of the photosensitive drum 2 and the center of the developing roller 3 is A1, the diameter of the photosensitive drum 2 is d, and the developing roller 3 is
The photosensitive drum 2 and the developing roller 3 are arranged so that the relationship of A1≤ (d + D) / 2 is satisfied, where D is the diameter of the photosensitive drum. Reference numeral 4 in the drawing is a toner cartridge.

Further, as shown in FIG. 7, the photosensitive drum 2
And the developing roller 3 are rotatably attached to the respective frames 5 and 6, and the frames 5 and 6 are rotatably supported by the shaft 7, so that the photosensitive drum 2 and the developing roller 3 are disposed between the frames 5 and 6. It is known that a spring 8 is hung on and pressed against.

However, since the photosensitive drum 2 and the developing roller 3 are always in pressure contact with each other, they are exposed to light when they are stored without being used for a long period of time or when they are used by the user after shipment from the factory for a long time. Since a specific position between the body drum 2 and the developing roller 3 is left in a pressure contact state for a long period of time, there arises a problem that the position is distorted and deformed.

From the above, Japanese Patent Laid-Open No. 5-2327
In Japanese Patent Laid-Open No. 52-52, as shown in FIG. 8, a photosensitive unit 9 having a photosensitive drum 2 and a developing unit 10 having a developing roller 3 are pivotally attached to each other, and the photosensitive drum 2 and the developing roller 3 are in pressure contact with each other. As described above, in which each unit 9 and 10 is biased by the spring 11, the spacer 12 is sandwiched between the contact surfaces of the units 9 and 10 and the photosensitive drum 2 and the developing roller 3 are pressed against each other when the spacer 12 is not used for a long time. I try to release the state.

[0006]

However, in the case where the spacer is simply sandwiched as described above, the spacer is again sandwiched when the process unit is again stored for a long period of time after the spacer is removed and used. It is troublesome to separately manage the spacer during the period of use, and there is a problem that the spacer is lost on the way.

Therefore, according to the present invention, the pressure contact state between the electrostatic latent image holding member and the developing roller can be released when the process unit is not used for a long period of time, and even when the process unit is not used for a long time, it is used. (EN) Provided is an image forming apparatus which does not have the trouble of separately managing a member such as a spacer that separates an electrostatic latent image holder from a developing roller.

[0008]

According to the first aspect of the present invention,
A process unit including an electrostatic latent image holder that holds an electrostatic latent image formed by exposure and a developing device that attaches toner to the electrostatic latent image held by the electrostatic latent image holder using a developing roller. In the image forming apparatus in which the process unit is detachably attached to the apparatus main body, the contact pressure between the electrostatic latent image holding member and the developing roller is made no pressure when the process unit is separated from the apparatus main body, and the process unit is attached to the apparatus main body. A positioning member for pressing the developing roller to the electrostatic latent image holding member when mounted is provided.

As a result, when the process unit is stored without being used for a long period of time, the contact pressure between the electrostatic latent image holder and the developing roller becomes a non-pressurized state simply by removing the process unit from the apparatus main body. When the process unit is attached to the apparatus main body during reuse, the developing roller comes into pressure contact with the electrostatic latent image holding member by the positioning member.

According to a second aspect of the present invention, an electrostatic latent image holding member holding an electrostatic latent image formed by exposure and a developing roller are used for the electrostatic latent image held by the electrostatic latent image holding member. In an image forming apparatus in which a process unit including a developing device for adhering toner is detachably provided in a main body of the apparatus, the process unit includes a spring member for press-contacting an electrostatic latent image holding member and a developing roller, and a spring of the spring member. A holding member for holding the electrostatic latent image holding member and the developing roller in a separated state is provided against the force, and the apparatus main body is provided with a holding release member for releasing the separated holding state of the holding member when the process unit is mounted. It is a thing. As a result, when the process unit is stored without being used for a long period of time, the process unit is detached from the apparatus main body and the holding member holds the electrostatic latent image holding member and the developing roller in a separated state. When the process unit is attached to the apparatus main body during reuse, the holding release member releases the holding state of the holding member, and the developing roller comes into pressure contact with the electrostatic latent image holding member.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) As shown in FIG. 1, a photosensitive drum 21 which is an electrostatic latent image holder is rotatably attached to a lower portion of a frame 22 by a rotary shaft 21a, and a developing roller 23 of a developing device is attached to the frame. It is rotatably attached to the lower part of 24 by a rotary shaft 23a. A developing device is incorporated in the frame 24, and a toner cartridge 25 for supplying new toner is provided on the frame 24.

The upper ends of the frames 22 and 24 are rotatably attached to a shaft 26 and integrated as a process unit. This process unit is provided in each frame 2 when it is in a single state without being attached to the main body of the image forming apparatus.
2, 24 are free about the shaft 26.

As shown in FIG. 2, the main body of the image forming apparatus is provided with a first guide cutout hole 27 for guiding the rotary shaft 21a of the photosensitive drum 21 and positioning it at a predetermined position. Positioning members 29 provided with second guide cutout holes 28 for guiding the rotary shaft 23a of the developing roller 23 and positioning it at a predetermined position are provided on both sides, and the positioning member 29 allows the photosensitive drum 21 and the developing roller 23 to be positioned. Are respectively positioned and supported. The second guide cutout hole 28 is bent so that the distance from the first guide cutout hole 27 is narrowed at the lowermost portion supporting the developing roller 23, and the rotation shaft 23a of the developing roller 23 is fixed. When positioned at the lowermost part of the second guide cutout hole 28, the developing roller 23 causes the photosensitive drum 21 to move.
It is designed to be pressed against.

In such a structure, the process unit is detached from the image forming apparatus main body and stored when it is not used for a long period of time. In this state, as shown in FIG. 1, the frames 22 and 24 are in a free state around the shaft 26, so that the contact pressure between the photosensitive drum 21 and the developing roller 23 is in a non-pressure state. Therefore, the state where the photosensitive drum 21 and the developing roller 23 are kept in pressure contact with each other for a long period of time does not occur. Thereby, the photosensitive drum 2
The problem that 1 or the developing roller 23 is deformed does not occur.

When used, the process unit is attached to the positioning member 29 of the image forming apparatus main body. That is, the rotary shaft 21a of the photosensitive drum 21 is set to the first position.
In the guide notch hole 27, the rotary shaft 23a of the developing roller 23 is inserted in the second guide notch hole 28, and is set at a predetermined positioning portion. As a result, the developing roller 23 is supported in pressure contact with the photosensitive drum 21, and the developing roller 23 can supply toner to the photosensitive drum 21.

Further, the photosensitive drum 21 and the developing roller 23
Since it is not necessary to use extra parts such as spacers for separating the process units, the structure of the process unit is simple and the process unit can be easily managed. Further, a spring member for pressing the developing roller 23 into pressure contact with the photosensitive drum 21 can be eliminated, and the structure of the process unit can be further simplified.

(Second Embodiment) As shown in FIG.
The photosensitive drum 31, which is an electrostatic latent image holder, is attached to the frame 32.
Is rotatably attached to the lower part of the frame by a rotary shaft 31a, and the developing roller 33 of the developing device is mounted on the lower part of the frame 34 by the rotary shaft 3a.
It is attached rotatably by 3a. Frame 3
A developing device is incorporated in the frame 4, and a toner cartridge 35 for replenishing new toner is provided on the frame 34.

The upper ends of the frames 32 and 34 are rotatably attached to a shaft 36 and integrated as a process unit. Then, a spring 37, which is a spring member, is installed between the rotary shaft 31a of the photosensitive drum 31 and the rotary shaft 33a of the developing roller 33, and the photosensitive drum 3
The developing roller 33 is brought into pressure contact with 1.

The rotary shaft 31 of the photosensitive drum 31
A holding member 38 is rotatably attached to a as shown in FIG. One end of the holding member 38 is rotatably attached to the rotary shaft 31a of the photosensitive drum 31, and the other end of the holding member 38 engages with the rotary shaft 33a of the developing roller 33.
And a locking projection 38b is attached to the other end side surface. The length of the holding member 38 is determined by the locking recess 38a.
Is locked to the rotary shaft 33a of the developing roller 33, the length is such that the photosensitive drum 31 and the developing roller 33 are separated from each other.

As shown in FIG. 4, the main body of the image forming apparatus is provided with a first guide cutout hole 39 for guiding the rotary shaft 31a of the photosensitive drum 31 and positioning it at a predetermined position. Positioning and holding release members 41 provided with projection guide cutout holes 40 for guiding the locking projection 38b of the holding member 38 to rotate the holding member 38b counterclockwise in the drawing are provided on both sides. The holding release member 41 positions and supports the photosensitive drum 21, and releases the locked state of the rotary shaft 33a of the developing roller 33 by the locking recess 38a of the holding member 38. That is, the protrusion guide notch 4
The lowermost part of 0 is located above the rotary shaft 33a of the developing roller 33, and when the locking projection 38b of the holding member 38 is locked to the lowermost part of the projection guide cutout hole 40, the holding member 38 is held. Rotates counterclockwise in the drawing around the rotation shaft 31a of the photoconductor drum 31, whereby the locking recess 38a of the holding member 38 comes off the rotation shaft 33a of the developing roller 33.

In such a structure, when the process unit is detached from the main body of the image forming apparatus and is stored for a long period of time, the holding member 38 is rotated clockwise as shown in FIG. Rotating shaft 33 of developing roller 33
a. As a result, the frames 32 and 34 are spread apart against the compressive force of the spring 37, and the photosensitive drum 31 and the developing roller 33 are separated from each other. Therefore, the state where the photosensitive drum 31 and the developing roller 33 are in pressure contact with each other at a specific position for a long period of time does not occur. That is, the problem that the photosensitive drum 31 and the developing roller 33 are deformed due to long-term storage of the process unit does not occur.

When using the process unit, the positioning and holding release member 41 of the image forming apparatus main body is used.
Attach to That is, the rotary shaft 3 of the photosensitive drum 31
1a is inserted into the first guide cutout hole 39, and the locking projection 38b of the holding member 38 is inserted into the projection guide cutout hole 4.
0, and the process unit is pushed down until the rotary shaft 31a of the photosensitive drum 31 is positioned at the bottom of the first guide cutout hole 39.

While the process unit is descending, the engaging projection 38b of the holding member 38 reaches the lowermost portion of the projection guide notch hole 40, and thereafter, the descending is stopped. This allows
The locking projection 38b of the holding member 38 is locked in the projection guide notch hole 40, and when the process unit further descends, the holding member 38 rotates counterclockwise in the figure around the rotation shaft 31a of the photosensitive drum 31. Move. By this rotation, the locked state of the locking recess 38a of the holding member 38 with respect to the rotation shaft 33a of the developing roller 33 is released. In this way, the rotary shaft 31a of the photoconductor drum 31 is aligned with the first guide notch hole 3
When it is positioned at the bottom of 9, the photosensitive drum 3
1 is supported in a state where the developing roller 33 is in pressure contact with
Toner can be supplied to the photosensitive drum 31 by the developing roller 33.

Since the holding member 38 is always attached to the rotary shaft 31a of the photosensitive drum 31, it does not separate when the process unit is used like a mere spacer, so that the management is surely performed. Therefore, even if the process unit is repeatedly stored and reused for a long period of time, the problem of losing the holding member 38 does not occur at all.

[0025]

As described above, according to the first aspect of the invention, when the process unit is not used for a long period of time, the contact pressure between the electrostatic latent image holding member and the developing roller can be kept in a non-pressurized state. Deformation does not occur in the electrostatic latent image carrier and the developing roller. Further, a member such as a spacer for separating the electrostatic latent image holding member and the developing roller can be eliminated, and a spring member for pressing the electrostatic latent image holding member and the developing roller into contact can be eliminated. Is easy and also
There is no need to manage members such as spacers.

According to the second aspect of the invention, when the process unit is not used for a long period of time, the electrostatic latent image holding member and the developing roller can be held in a separated state, and the electrostatic latent image holding member and the developing roller can be held. There is no deformation. Further, since the holding member for separating the electrostatic latent image holding member and the developing roller is not separated from the process unit, there is no trouble of separately managing this holding member.

[Brief description of drawings]

FIG. 1 is a side view of a single process unit showing a first embodiment of the present invention.

FIG. 2 is a partially cutaway side view when the process unit according to the embodiment is set on the positioning member of the apparatus main body.

FIG. 3 is a side view of a single process unit showing a second embodiment of the present invention.

FIG. 4 is a partially cutaway side view when the process unit according to the embodiment is set on the positioning and holding release member of the apparatus main body.

FIG. 5 is a partially enlarged perspective view showing a configuration of a main part of the same embodiment.

FIG. 6 is a side view showing a conventional example.

FIG. 7 is a side view showing another conventional example.

FIG. 8 is a side view showing another conventional example.

[Explanation of symbols]

 21 ... Photosensitive drum (electrostatic latent image holder) 23 ... Developing roller 22, 24 ... Frame 27 ... First guide cutout hole 28 ... Second guide cutout hole 29 ... Positioning member

Claims (2)

[Claims] 1. An electrostatic latent image holder that holds an electrostatic latent image formed by exposure, and a developing device that attaches toner to the electrostatic latent image held by the electrostatic latent image holder using a developing roller. In an image forming apparatus in which a process unit including a process unit is detachably provided in an apparatus main body, a contact pressure between the electrostatic latent image holding member and a developing roller is set to a non-pressure state when the process unit is separated from the apparatus main body. An image forming apparatus, wherein the apparatus body is provided with a positioning member that presses the developing roller against the electrostatic latent image holder when the process unit is mounted. 2. An electrostatic latent image holding member that holds an electrostatic latent image formed by exposure, and a developing device that attaches toner to the electrostatic latent image held by the electrostatic latent image holding member by using a developing roller. In the image forming apparatus in which the process unit including the process unit is detachably provided in the apparatus main body, the process unit includes a spring member for pressing the electrostatic latent image holding member and the developing roller into contact with each other, and a spring force against the spring member. And a holding member for holding the electrostatic latent image holding member and the developing roller in a separated state, and the apparatus main body is provided with a holding release member for releasing the held state of the holding member when the process unit is mounted. An image forming apparatus characterized by the above.