JPH0619235A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To provide the electrophotographic device with an economical construction where a photosensitive drum and a developing roll in a processing unit are held in a specified relative position. CONSTITUTION:The device is provided with the electrophotographic device main body 1 and a processing unit 2 which is attachable to the main body, a photosensitive drum 4 disposed to a unit case 3 and a developing device 7 with a developing roll 11 are provided to the processing unit 2 and a leaf spring 8 holding the positions of the photosensitive drum 4 and the developing roll 11 to be fixed in a state where the processing unit 2 is attached to the electrophotographic device main body 1, in the electrophotographic device main body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus used in facsimiles, copying machines and the like.

[0002]

2. Description of the Related Art An electrophotographic apparatus forms an image in a recording process described below.

That is, the photosensitive drum drum is rotated, the surface of the photosensitive drum is charged by the charging device, an electrostatic latent image is formed on the surface of the photosensitive drum by the exposure device, and then the electrostatic latent image is formed by the developing device. Toner is supplied to the surface of the body drum to develop the electrostatic latent image and form a toner image. Then, the transfer device transfers the toner image on the surface of the photosensitive drum onto the recording paper, and the fixing device fixes the toner image on the recording paper.

Recently, in this electrophotographic apparatus, a process unit is constructed by supporting a device that uses a photosensitive drum in a recording process, such as a charging device, a developing device, and a cleaning device, in a common unit case. The method of removably attaching the to the main body of the electrophotographic apparatus is adopted. In this system, the user can easily replace the photosensitive drum by replacing the process unit.

On the other hand, in the electrophotographic apparatus, the developing roller provided in the developing apparatus contacts the surface of the photosensitive drum depending on the type of the developing system, and the developing roller has a gap with respect to the surface of the photosensitive drum. There are cases where they face each other openly.
In any case, it is important to position the developing roller parallel to the photosensitive drum in order to obtain a uniform and high quality image.

Also in the process unit, any one of the above-mentioned methods is adopted for the positional relationship between the photoconductor drum and the developing roller. In order to position the developing roller in parallel with the photoconductor drum, the conventional method is as follows. The method described is used.

One of them is that the developing device is provided in a unit case so as to be displaceable along the direction of approaching and separating from the photosensitive drum, and the developing device is pressed by a biasing member such as a leaf spring provided in the unit case. Then, the developing roller is held at a position where it contacts the photosensitive drum.

In another method, the developing device and the photosensitive drum are positioned relative to each other and fixed to the unit case. For example, the developing device and the photosensitive drum are fixed at a position where the developing roller and the photosensitive drum contact each other.

[0009]

However, in the former method, since the unit case is provided with the biasing member for biasing the developing device, when the process unit is replaced, the biasing member is replaced. There is no need to do it, but it will be forcibly replaced as part of the unit and the economy is poor.

In the case of the latter method, it is not necessary to provide a biasing member on the unit case, but it is necessary to fix the photosensitive drum and the developing device to the unit case with a high degree of accuracy at positions where a predetermined positional relationship can be maintained. Therefore, it takes a lot of time and effort to assemble the photoconductor drum and the developing device, which is very economical.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrophotographic apparatus economically realizing a structure for holding a photosensitive drum and a developing roller in a process unit in a predetermined positional relationship. To do.

[0012]

In order to achieve the above object, an electrophotographic apparatus of the present invention comprises an electrophotographic apparatus main body and a process unit detachably attached to the electrophotographic apparatus main body, This process unit has a unit case, a photoconductor drum, and a developing roller, and includes a developing device provided in the unit case. The process unit is attached to the electrophotographic apparatus main body. In this state, a position holding member that holds the positions of the photosensitive drum and the developing roller constant is provided.

In the electrophotographic apparatus of the present invention, the developing device is provided in the unit case so as to be displaceable toward and away from the photosensitive drum, and the position holding member provided in the main body of the electrophotographic apparatus is , A biasing member that applies a force to the developing device in a direction approaching the photosensitive drum.

[0014]

The photosensitive drum and the developing roller of the developing device are accurately held in a predetermined positional relationship by the position holding member provided in the main body of the electrophotographic apparatus. Therefore, it is not necessary to provide a position holding member in the process unit in order to hold the photosensitive drum and the developing roller in a predetermined positional relationship, and it is necessary to fix the photosensitive drum and the developing roller to the unit case of the process unit. Absent.

If the developing device is provided movably and the urging member for urging the developing device as a position holding member is provided in the unit case, the positional relationship between the photosensitive drum and the developing roller is combined. Can be held accurately with a cheaper structure.

[0016]

EXAMPLES Examples of the present invention will be described. A first embodiment will be described with reference to FIGS. In this embodiment, the photosensitive drum and the developing roller are brought into contact with each other.

FIG. 3 shows the entire electrophotographic apparatus. In the figure, 1 is a main body of an electrophotographic apparatus, and a process unit 2 is provided inside the main body 1 of the apparatus. The process unit 2 will be described with reference to FIGS. 1 and 2. Reference numeral 3 is a unit case, and the unit case 3 is detachably supported by the electrophotographic apparatus main body 1 by appropriate means. A photosensitive drum 4 is arranged inside the unit case 3. The photosensitive drum 4 is supported by a drum shaft 5, and the drum shaft 5 is rotatably supported by a bearing 6 provided in the unit case 3. Inside the unit case 3, a developing device 7 is provided on one side of the photosensitive drum 4 and is supported by the unit case 3.
A cleaner device 8 and a charging device 9 are provided on the other side and are supported by the unit case 3.

The developing device 7 comprises a developing device case 10.
Toner T is stored inside the case 10.
A side portion of the developing device case 10 facing the photosensitive drum 4 is opened, and a developing roller 11 is arranged in parallel with the photosensitive drum 4 in the opened portion. The developing roller 11 is supported by a roller shaft 12, and both ends of the roller shaft 12 are rotatably supported by bearings 13 provided on both sides of the case 8.

At opposite positions on both sides of the developing device case 10, support bars 14 parallel to the developing roller 11 are provided so as to project toward the outside. Both ends of the roller shaft 12 are projected toward the outside of the developing device case 10.

At both sides of the unit case 3 where the developing device 7 is sandwiched, circular holes 15 through which the support rods 14 are inserted are formed. These holes 15 are support rods 14
It has a larger diameter. Also, the unit case 3
Long holes 16 through which both ends of the roller shaft 12 are inserted are formed in the portions on both sides of which the developing device 7 is sandwiched. These elongated holes 16 have a diameter larger than that of the roller shaft 12, and are formed at right angles to the roller shaft 12 and linearly along the direction in which the developing roller 11 approaches and separates from the photosensitive drum 2. Has been done. Only one of the hole 15 and the slot 16 is shown in the drawing.

The support rods 14 provided on both sides of the developing device case 10 are inserted into the holes 15 formed on both sides of the unit case 3, respectively. Support rod 14 has hole 1
It becomes a state with play for 5. Also, the developing roller 1
Rollers 17 are attached to both ends of the first roller shaft 12, and the rollers 17 are inserted into the long holes 16 formed on both sides of the unit case 3, respectively. The roller shaft 12 is movable along the long hole 16. For this reason, the developing device 7, that is, the developing roller 11 is supported by the unit case 3 so as to be linearly movable in a direction toward and away from the photosensitive drum 4. The movable distance of the developing device 7 is the size of the diameter of the hole 15 minus the diameter of the support rod 14. The reason why the hole 15 is circular and the hole 16 is long is as follows.

On the other hand, at the rear of the electrophotographic apparatus main body 1, a biasing member for applying a force to the developing device 7 toward the photoconductor drum 4 in a state where the process unit 2 is mounted on the electrophotographic apparatus main body 1. As an example, two leaf springs 18 are attached. In the figure, only one is shown. These leaf springs 18 are arranged at intervals in the width direction of the electrophotographic apparatus main body 1, and one ends thereof are fixed to the rear portion of the electrophotographic apparatus main body 1. Each leaf spring 18 is formed so as to extend from one end toward the lower front and enter the inside of the unit case 3, and the other end abuts the rear surface of the developing device case 10 to press the developing device case 10. At the rear of the unit case 3, the unit case 3 is attached to the electrophotographic apparatus main body 1,
It is opened so as to escape from the leaf spring 18 so that the leaf spring 18 does not collide when being removed. A recording paper cassette 19 and a transfer device 2 are provided inside the electrophotographic apparatus main body 1.
0, a fixing device 21, and the like.

In the electrophotographic apparatus constructed as described above, when the process unit 2 is detached from the electrophotographic apparatus main body 1, the developing device 7 of the process unit 2 is as shown by solid lines and phantom lines in FIG. It is in a movable state along the direction of the arrow in the diagram.

The process unit 2 is the electrophotographic apparatus main body 1.
In the state in which the developing device 7 is mounted on, the case 10 of the developing device 7 is pushed by a pair of leaf springs 18 provided in the electrophotographic apparatus main body 1 and linearly moved in a direction of approaching the photosensitive drum 4, and is supported by the case 10. The developing roller 11 is brought into contact with the photosensitive drum 4 supported by the electrophotographic apparatus main body 1. And
The developing roller 11 is kept in contact with the photosensitive drum 4. Therefore, the photosensitive drum 4 and the developing roller 11 are held in a predetermined positional relationship with each other.

In this embodiment, a biasing member for holding the photosensitive drum 4 and the developing roller 11 in a predetermined positional relationship is provided in the electrophotographic apparatus main body 1, and the process unit 2 is provided.
Since it is not necessary to provide the urging member to the unit case 3, the urging member is not removed together with the process unit 2 every time the process unit 2 is replaced, which is economical.

Further, in order to hold the photosensitive drum 4 and the developing roller 11 in a predetermined positional relationship, it is necessary to position and fix the photosensitive drum 4 and the developing roller 11 at a predetermined position of the unit case 10 with high accuracy. Therefore, the photosensitive drum 4 and the developing roller 11 can be easily assembled, and the manufacturing cost can be reduced, which is economical.

FIG. 4 shows a second embodiment. 4, the same parts as those in FIG. 2 are designated by the same reference numerals,
In this embodiment, the case 10 of the developing device 7 is pivotally supported by the unit case 3 in a system in which the photosensitive drum 4 and the developing roller 11 are in contact with each other.

That is, standing portions 3a are formed on both sides of the unit case 3, and the unit case 3 serves as the pivot 2
It is supported by the upright portion 3a by 2 so as to rotate along a direction in which the photosensitive drum 4 approaches and separates. Both ends of the roller shaft 12 of the developing roller 11 may be independent of the unit case 3, or may be inserted in the unit case 3 into an elongated hole formed in an arc shape around the pivot 22. 5 and 6 show a third embodiment.
5, the same parts as those in FIG. 2 are designated by the same reference numerals. In this embodiment, the photosensitive drum 4 and the developing roller 11 are opposed to each other with a space therebetween without contacting each other.

Although there are various means for allowing the photosensitive drum 4 and the developing roller 11 to face each other with a space, in this embodiment, as shown in FIG. 6, flanges are provided on both ends of the developing roller 11 which are not directly used for developing. 23 is formed. That is, when the flanges 23 at both ends of the developing roller 11 come into contact with both ends of the photoconductor drum 4, the difference between the radius of the flange 23 and the radius of the developing roller 11 is determined between the photoconductor drum 4 and the developing roller 11. A size interval is formed. In this embodiment, the developing device 7 is installed in the unit case 3
In order to support the above, for example, the configuration shown in the first embodiment is adopted.

The present invention is not limited to the above-mentioned embodiments, but can be implemented with various modifications. For example, a spring may be provided in the unit case that presses the developing device in a direction away from the photoconductor drum when the process unit is removed from the electrophotographic apparatus main body. It is smaller than the force of the biasing member.

[0031]

As described above, according to the electrophotographic apparatus of the present invention, the photosensitive drum in the process unit and the developing roller of the developing device have a predetermined positional relationship by the position holding member provided in the main body of the electrophotographic apparatus. It is not necessary to provide a position holding member in the process unit in order to hold the photosensitive drum and the developing roller in a predetermined positional relationship, and the photosensitive drum and the developing roller are held in the unit case of the process unit. There is no need to fix it to.
Therefore, it is possible to very economically realize a configuration in which the photosensitive drum and the developing roller are held in a predetermined positional relationship.

If the developing device is movably provided and the position holding member is provided in the unit case as an urging member for urging the developing device, the positional relationship between the photosensitive drum and the developing roller is combined. Can be held accurately with a cheaper structure.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a process unit according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a part of a process unit in the embodiment.

FIG. 3 is a cross-sectional view showing a schematic configuration of the entire electrophotographic apparatus in the embodiment.

FIG. 4 is a sectional view showing a schematic configuration of a process unit according to a second embodiment.

FIG. 5 is a sectional view showing a schematic configuration of a process unit according to a third embodiment.

FIG. 6 is a perspective view showing a photosensitive drum and a developing roller in the embodiment.

[Explanation of symbols]

1 ... Electrophotographic apparatus main body, 2 ... Process unit, 3 ... Unit case, 4 ... Photosensitive drum, 7 ... Developing device, 10
... developing device case, 11 ... developing roller, 18 ... leaf spring.

Claims (2)

[Claims] 1. An electrophotographic apparatus main body, and a process unit detachably attached to the electrophotographic apparatus main body, the process unit having a unit case, a photosensitive drum and a developing roller, and the unit case. A position holding unit for holding the position of the photosensitive drum and the developing roller constant in the state where the process unit is mounted on the electrophotographic apparatus body. An electrophotographic apparatus comprising a member. 2. A developing device is provided in a unit case so as to be displaceable toward and away from the photoconductor drum, and a position holding member provided in the main body of the electrophotographic device is exposed to the developing device. The electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus is a biasing member that applies a force toward a direction approaching the body drum.