JPH0996937A - Electrophotographic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deformation of the surface of a developing roller and separation of the elastic member of the surface which are caused in case where the developing roller is in pressure contact with a photoreceptive drum with an image formation unit unloaded. SOLUTION: A spring 8 is provided for pressing the bearing 6 of the developing roller 3 held on the image formation unit 1, and a plate spring 20 is provided opposite side of the spring 8 in relation to the bearing 6. The plate spring 20 presses the bearing 6 in such a way as to move it apart from the photoreceptive drum 2. The pressing force of the plate spring 20 is stronger than the pressing force of the spring 8. A projecting part 23 is formed on the device main body side, and releases the press of the plate spring 20 when the image formation unit 1 is loaded on it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus in which an image forming unit can be attached to and detached from an apparatus main body.

[0002]

2. Description of the Related Art Heretofore, in some electrophotographic recording apparatuses, an image forming unit including a developing section has been made detachable from the apparatus main body. This facilitates replacement of consumable items such as the photosensitive drum. The image forming unit is provided with a developing roller in addition to the photosensitive drum, and the developing roller formed by molding an elastic material on a metallic cored bar is pressed against the photosensitive drum at a predetermined pressure.

[0003]

However, in the above-mentioned conventional electrophotographic recording apparatus, the developing roller is pressed against the photosensitive drum even when the image forming unit is detached from the main body of the apparatus, and printing is performed after manufacturing. It remains pressed until it is used. Since the surface of the developing roller is made of an elastic material such as rubber, the contact portion with the photosensitive drum is deformed by pressing. If printing is started in this state, the developing function in the deformed portion of the developing roller may be deteriorated, and the rubber component in the deformed portion may be deposited and adhere to the photosensitive drum. In any case, good image quality cannot be obtained, and there is a problem that it takes time from the start of printing until good image quality is obtained.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a roller member having an outer peripheral surface made of an elastic body is pressed against a pressed member by a pressing member to operate the apparatus, and the pressed member is operated. A detachable unit including a detachable unit that is attached to the detachable unit in an electrophotographic recording apparatus that is attachable to and detachable from an apparatus main body that includes an engaging member that engages with the pressed member, and that releases the pressing of the roller member by the pressing member. 1 release means and a second release means which is attached to the apparatus main body and releases the pressure release by the first release means when the detachable unit is mounted.

According to the present invention having the above-mentioned structure, when the detachable unit is not attached to the apparatus main body,
The releasing means releases the pressing of the roller member against the pressed member by the pressing member. Therefore, the surface of the roller member is not deformed. When the detachable unit is attached to the apparatus body, the release by the first release means is released by the second release means. As a result, the roll member presses the pressed member by the pressing member, and the operation of the apparatus can be started. That is, since it takes a relatively short time from the time when the roll member starts pressing the pressed member to the start of the operation of the apparatus, the surface of the roll member is not deformed and a good image is obtained from the beginning of the operation.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are assigned the same reference numerals. 1 is a perspective view showing a first embodiment of the present invention, and FIG. 2 is a schematic side view showing an electrophotographic recording apparatus.

In FIG. 2, the electrophotographic recording apparatus 10 is detachably provided with an image forming unit 1, and the image forming unit 1 is integrally formed with a photosensitive drum 2, a developing roller 3 and the like. The image forming unit 1 is removed upward by opening the paper discharge unit 11 on the apparatus 10 side. The apparatus 10 main body is provided with a pickup roller 12, a conveyance roller 13, a fixing device 14, and the like.

In FIG. 1, an image forming unit 1 is mounted on an electrophotographic recording apparatus and has a photosensitive drum 2 and a developing roller 3 inside. The photosensitive drum 2 and the developing roller 3 are rotatably supported by the housing 1 a of the image forming unit 1. A gear 4 is fixed to an end portion of the photosensitive drum 2, and a drive gear (not shown) is meshed with the gear 4 to rotate the photosensitive drum 2 via the gear 4. The developing roller 3 is a roller formed by cylindrically winding an elastic body such as rubber having conductivity on a metallic core, and forms a thin layer of toner on the surface by a thin layer forming means (not shown). During the printing operation, a bias voltage is applied by the voltage applying means to develop the latent image on the surface of the photosensitive drum 2.

A gear 5 is fixed to the end of the developing roller 3, and the gear 5 can mesh with the gear 4 of the photosensitive drum 2. A bearing 6 is fitted on the shaft 3a of the developing roller 3, and the bearing 6 is slidably inserted into a groove 7 formed in the unit casing 1a so as to be long in the lateral direction. A spring 8 is mounted in the groove 7, and the spring 8 urges the bearing 6 toward the photosensitive drum 2. The developing roller 3 comes into contact with the photosensitive drum 2 with a predetermined pressure by the spring 8, the gear 5 and the gear 4 mesh with each other, and both rollers 2 and 3 rotate at the same time. The peripheral speed on the surface of the photosensitive drum 2 and the peripheral speed on the surface of the developing roller 3 are set by a gear ratio so that the ratio is about 1: 1 to 1: 1.5.

A protrusion 9 is formed on the bearing 6 in a direction projecting from the unit 1. A leaf spring 20 is attached to the unit housing 1a. This leaf spring 20 is a cantilever spring whose one end is fixed by a screw, and an intermediate portion 20a thereof.
Contacts the convex portion 9 and urges the bearing 6 away from the photosensitive drum 2. The other end 20b of the leaf spring 20 has a protrusion 9
Is bent to the side opposite to the above so as to easily engage with a protrusion of the main body of the device 10 described later. The biasing force of the leaf spring 20 is set to be larger than the biasing force of the spring 8. A positioning protrusion 21 is formed on the unit housing 1 a facing the axis of the photosensitive drum 2.

A pedestal portion 22 and a projection portion 23 are formed on the main body side of the apparatus 10, and the groove portion 2 is formed on the pedestal portion 22.
4 are formed. The groove 24 is provided in the image forming unit 1
When the image forming unit 1 is attached to the apparatus 10, the positioning protrusion 21 is fitted thereto, and the protrusion 23 displaces the leaf spring 20 in the direction of separating from the convex portion 9 of the bearing 6 when the image forming unit 1 is attached to the apparatus 10. .

Although only one side of the image forming unit 1 has been described above, the other side of the image forming unit 1 has the same structure.

Next, the operation of the first embodiment will be further described with reference to FIGS. 3 and 4 are side views showing the operation of the first embodiment. FIG. 3 shows a state where the image forming unit is not attached, and FIG. 4 shows a case where the image forming unit is attached.

In FIG. 3, when the image forming unit 1 is not attached to the main body of the apparatus 20, the intermediate portion 20a of the leaf spring 20 is used.
Urges the convex portion 9 of the bearing 6 in a direction away from the photosensitive drum 2. Since the urging force of the leaf spring 20 is larger than the urging force of the spring 8, the bearing 6 moves in the direction away from the photosensitive drum 2 and the developing roller 3 separates from the photosensitive drum 2. That is, the bias of the developing roller 3 to the photosensitive drum 2 by the spring 8 is released. Therefore, the surface of the developing roller 3 is not exposed to the photosensitive drum 2.
Deformation due to pressure contact with does not occur. Further, it is possible to prevent the components of the elastic member on the surface of the developing roller from depositing.

In FIG. 4, when the image forming unit 1 is mounted on the main body of the apparatus 20, the positioning projection 21 formed on the unit housing 1a is fitted into the groove 24 of the main body of the apparatus 20. The forming unit 1 is positioned. After that, the image forming unit 1 is held in the main body of the apparatus 20 by a holding means (not shown). Further, at the time of mounting, the protrusion 23 makes the other end 20 of the leaf spring 20.
Displace b in the direction of the photosensitive drum 2. As a result, the intermediate portion 20 a of the leaf spring 20 separates from the convex portion 9 of the bearing 6. That is, the urging of the leaf spring 20 on the bearing 6 is released.

When the bias by the leaf spring 20 is released, the bearing 8 is biased toward the photosensitive drum 2 by the spring 8, and the developing roller 3 presses the photosensitive drum 2. With the developing roller 3 pressing the photosensitive drum 2, the intermediate portion 20 of the leaf spring 20 is
a does not contact the convex portion 9 of the bearing 6. This enables the image forming operation.

As described above, according to the first embodiment,
When the image forming unit 1 is detached from the main body of the apparatus 20, the developing roller 3 is not in a state of pressing the photosensitive drum 2, so that it is possible to prevent the deformation of the surface of the developing roller and the deposition of the component of the elastic member. Further, the deformation amount of the other end 20b of the leaf spring 20 when the image forming unit 1 is mounted is such that the intermediate portion 20a of the leaf spring 20 is separated from the convex portion 9 with the developing roller 3 pressing the photosensitive drum 3. Therefore, the accuracy is not strictly required. Therefore, the precision of the shape of the leaf spring 20 and the shape of the protrusion 23 is not so important, and these parts can be manufactured at low cost.

Next, a second embodiment of the present invention will be described. FIG. 5 is a perspective view showing the second embodiment. Second
In the second embodiment, in addition to the configuration of the first embodiment, a holding unit that holds the image forming unit when the image forming unit 1 is attached to the apparatus main body is provided.

In FIG. 5, a bearing 6 is attached to the end of the developing roller 3, and the bearing 6 is pressed toward the photosensitive drum 2 by a spring 8. The bearing 6 is formed with a convex portion 9. One end of a leaf spring 30 is attached to the unit housing 1a with a screw, and the other end 30a, which is a free end, can be pressed against the convex portion 9 of the bearing 6. The pressing force of the other end 30a is set to be larger than the pressing force of the spring 8.
Another cantilever spring 31 is fixed to the middle portion 30b of the leaf spring 30. The cantilever spring 31 is formed in a substantially L shape and is arranged so as to straddle the positioning projection 21. A curved portion 32 is formed at the other end (free end) of the cantilever spring 31,
Furthermore, the tip 31a thereof is inclined.

A pedestal portion 33 is provided on the main body of the apparatus 10, and a groove portion 34 is formed on the pedestal portion 33. The groove 34 fits with the positioning protrusion 21 of the unit 1. A curved protrusion 35 is formed on the side of the cradle 33. The protruding portion 35 is locked to the curved portion 32, and is a pedestal portion 33 on the side where the protruding portion 35 is provided.
a is located slightly outside the cantilever spring 31 with respect to the vertical direction.

Next, the operation of the second embodiment will be described with reference to FIGS. 6 and 7. 6 and 7 are side views showing the operation of the second embodiment, FIG. 6 shows a state in which the image forming unit is not attached, and FIG. 7 shows a state in which the image forming unit is not attached.

In FIG. 6, when the image forming unit 1 is not attached to the main body of the apparatus 10, the other end 30a of the leaf spring 30 is used.
Presses the convex portion 9 of the bearing 6 and separates the developing roller 3 from the photosensitive drum 2 against the biasing force of the spring 8. That is, as in the case of the first embodiment, it is possible to prevent the deterioration of the image quality due to the deformation of the elastic member of the developing roller or the deposition of components even during long-term storage.

In FIG. 7, when the image forming unit 1 is mounted on the main body of the apparatus 10, the positioning projection 21 fits into the groove 34 of the pedestal 33. At the same time, the other end 31a of the cantilever spring 31 is displaced in the direction of the arrow A by the side portion 33a of the pedestal part 33, and the other end 30a of the leaf spring 30 is protruded.
Move away from As a result, the bearing 6 is pressed toward the photosensitive drum 2 by the spring 8, and the developing roller 3 presses the photosensitive drum 2. The other end 30a of the leaf spring 30 is not in contact with the convex portion 9 while the developing roller 3 is pressing the photosensitive drum 2 with a predetermined force. As a result, the image forming unit 1 becomes operable.

When the positioning projection 21 is fitted in the groove 34, the curved portion 32 of the cantilever spring 31 locks the projection 35. As a result, the image forming unit 1 becomes the device 1
0 It is in a state of being vertically positioned with respect to the main body.

As described above, in the second embodiment, when the image forming unit 1 is mounted, not only the unit 1 is made operable, but also the unit 1 is held. It is not necessary to provide a dedicated holding member for holding the forming unit 1, the number of parts can be reduced, and an inexpensive device can be provided.

In each of the above embodiments, the present invention has been described with respect to the mounting of the image forming unit including the photosensitive drum and the developing roller, but the pressing of the roller or the like which is easily deformed by the mounting operation of the unit to the apparatus main body is released. It suffices if the fixing unit can be released. For example, the present invention can be applied to such a fixing unit by releasing the pressure between the fixing roller and the pressure roller in the fixing unit when the fixing unit is removed from the electrophotographic recording apparatus main body. Is.

[0027]

As described above in detail, according to the present invention, the pressing releasing means which is attached to the detachable unit and releases the pressing of the roller member by the pressing member, and the detachable unit which is attached to the main body of the apparatus. Since the release releasing means for releasing the release of the pressure by the pressure releasing means when mounted is provided, since the pressing of the roller member is released by the pressure releasing means when the detachable unit is not mounted on the apparatus main body. Further, it is possible to prevent the deformation of the surface of the roller member and the deposition of the components, so that good image quality can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment.

FIG. 2 is a schematic side view showing an electrophotographic recording apparatus.

FIG. 3 is a side view showing the operation of the first embodiment.

FIG. 4 is a side view showing the operation of the first embodiment.

FIG. 5 is a perspective view showing a second embodiment.

FIG. 6 is a side view showing the operation of the second embodiment.

FIG. 7 is a side view showing the operation of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Photosensitive drum 3 Developing roller 8 Spring 20 Leaf spring 23 Projection portion 30 Leaf spring 31 Cantilever spring 32 Curved portion 35 Projection portion

Claims (3)

[Claims] 1. A device is operated by pressing a roller member whose outer peripheral surface is formed of an elastic body against a pressed member by a pressing member,
In an electrophotographic recording device in which an attachable / detachable unit including the pressed member is attachable / detachable to / from an apparatus main body including an engaging member with which the pressed member engages, a pressing of a roller member by the press member is attached to the attachable / detachable unit. And a second releasing means that is attached to the apparatus body and that releases the pressing release by the first releasing means when the detachable unit is attached. Electrophotographic recording device. 2. The electrophotographic recording apparatus according to claim 1, further comprising holding means for holding the detachable unit when the detachable unit is attached to the apparatus main body. 3. The first releasing means is formed of a leaf spring, the second releasing means is formed of a projection portion, and the holding means is formed in a concave portion and the protrusion portion formed in the leaf spring. The electrophotographic recording apparatus according to claim 2, comprising a raised portion.