JP2002196651A - Processing unit and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately position a photoreceptor drum to a developing unit or the like provided in a unit cover. SOLUTION: The processing unit has the photoreceptor drum in which holding holes are formed on a pair of end surface parts, a photoreceptor case which has a pair of end wall parts, in which fitting holes are formed at a location of the end wall parts on a straight line connecting the end wall parts, and a photoreceptor drum is arranged on the straight line on which each fitting hole is located, a pair of holding members in which a first shaft part to be fitted into the fitting holes of the pair of end wall parts of the photoreceptor case, and a second shaft part inserted into the holding holes of the photoreceptor drum are integrally formed on a straight line, and a engagement part is formed in the first shaft part, and the unit cover in which positioning parts are formed at locations of a pair of end plate parts on a straight line connecting the end plate parts, the photoreceptor case is arranged on the straight line where each positioning part is located between a pair of the end plate parts, and the positioning parts engages with the engagement parts of the holding member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a process unit and an image forming apparatus provided with the process unit.

[0002]

2. Description of the Related Art Recently, in an image forming apparatus used for a facsimile, a printer, or the like, a vertical conveyance system is being adopted in order to reduce an installation area of an apparatus main body. The image forming apparatus of the vertical transport type includes a photosensitive drum and a developing device that develops an electrostatic latent image formed on the photosensitive drum and forms a toner image on one side of a vertical recording paper transport path. A transfer device is provided on the other side for transferring the toner image on the photosensitive drum to recording paper conveyed on the conveyance path, and an image is formed while the recording paper is conveyed from the lower side to the upper side.

In some image forming apparatuses of this type, a photosensitive drum and a developing unit are combined to form a process unit. The process unit is provided between a pair of end plates provided on a unit cover. The unit and the developing device are arranged and held in parallel. The photoreceptor unit is configured by disposing and holding a photoreceptor drum and a charger between a pair of end walls provided in a photoreceptor case. Also,
The process unit is removably mounted inside the main body of the image forming apparatus for maintenance and inspection or replacement.

[0004] In a vertical conveyance type image forming apparatus,
Since the transfer unit makes it difficult to put the process unit in and out from the upper side of the apparatus main body, the process unit is moved in and out of the apparatus main body in the unit axial direction, that is, in the lateral direction.

[0005]

Conventionally, in a process unit provided in an image forming apparatus of the above-described vertical conveyance type, when a photosensitive member unit (a photosensitive drum and a developing device) is held on a unit cover, the unit cover is not used. A reference position is set at a position independent of the photosensitive drum and the developing device on the pair of end plates provided, and the holding positions of the photosensitive drum and the developing device are respectively set based on this position, and the photosensitive unit and the developing device are set. The container is placed and held.

However, in the setting of the holding position of the photoconductor unit and the developing unit, a good position in the positional relationship between the reference position on the unit cover and the center axis of the photoconductor drum, and the reference position and the developing device is good. The settings are made,
Since the position is not directly set between the center axis of the photosensitive drum and the developing device, the required level of position setting accuracy may not be ensured. This may adversely affect the developing action of the developing device on the electrostatic latent image on the photosensitive drum.

When the process unit is mounted on the apparatus main body, a portion of the unit cover that is independent of the center axis of the photosensitive drum is combined with a position setting member provided on the apparatus main body, and the combined position is used as a reference. The positional relationship between the center axis of the process unit, that is, the photosensitive drum and a mechanism such as a transfer unit provided in the apparatus main body is set.

However, the position between the central axis of the photosensitive drum and the mechanism provided in the apparatus main body is set directly by setting the positional relationship between the central axis of the photosensitive drum and other mechanisms. Is not performed, it may not be possible to perform position setting with a required level of accuracy. This may adversely affect the operation of forming an image by the photosensitive drum and the mechanism provided in the apparatus main body.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process unit capable of accurately setting the position of a photosensitive drum with respect to a mechanism such as a developing device provided on a unit cover.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus having a process unit capable of accurately setting the position of the process unit with respect to a mechanism provided in the apparatus main body.

[0011]

According to a first aspect of the present invention, there is provided a process unit, comprising: a pair of photoconductor drums having a pair of end faces formed with a holding hole positioned on a center axis; The pair of end walls have end walls, and a pair of end walls are formed with fitting holes located on the same straight line connecting them, and on the straight line where the fitting holes are located between the pair of end walls. A photoreceptor case in which the photoreceptor drum is disposed, a first shaft portion fitted into the fitting hole of a pair of end walls of the photoreceptor case, and the pair of first shaft portions with respect to the first shaft portion; A second shaft portion, which is located inside the end wall portion of the photosensitive drum and inserted into the holding hole in the end surface portion of the photosensitive drum, is integrally formed on the same straight line, and the second shaft portion is formed on the first shaft portion. A pair of holding members, each having an engaging portion formed on the opposite side to the shaft portion, Positioning portions are formed on the same straight line connecting them to the pair of end plate portions, and the positioning portions are formed on the straight line where the positioning portions are located between the pair of end plate portions. And a unit cover in which the photosensitive member case is disposed, wherein the positioning portion is engaged with an engaging portion of the holding member fitted in the fitting hole of the photosensitive member case.

According to the structure of the present invention, by positioning the unit cover on the center axis of the photosensitive drum via the holding member, a mechanism such as a developing device which holds the center axis of the photosensitive drum and the unit cover is provided. Can be set based on the center axis of the photosensitive drum,
The position can be set with a required level of accuracy between the center axis of the photosensitive drum and a mechanism such as a developing unit.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a process unit according to the first aspect; a transfer unit provided in the process unit for transferring a toner image of the photosensitive drum onto recording paper; And an apparatus main body having a transfer unit mounted therein and having an access port for moving the process unit along the axial direction thereof and taking the process unit in and out, wherein the positioning unit is located on the unit cover provided in the process unit. When the process unit is loaded into the apparatus main body from the access port on the inner surface of a wall portion of the apparatus main body which is formed on a straight line to be formed, and is opposed to the access port. A main body-side positioning member that engages with the main body positioning portion of the unit cover provided in the process unit is provided; And wherein the Rukoto.

According to the structure of the present invention, the apparatus main body is positioned on the center axis of the photosensitive drum via the unit cover of the process unit and the holding member, whereby
The positional relationship between the center axis of the photoconductor drum and the mechanism provided in the apparatus main body can be set with reference to the center axis of the photoconductor drum, which is necessary between the center axis of the photoconductor drum and the mechanism provided in the apparatus main body. The position can be set with a level of accuracy.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

This embodiment is directed to a vertical conveyance type image forming apparatus and a process unit provided in the image forming apparatus. FIG. 1 is a perspective view showing an appearance of the image forming apparatus, FIG. 2 is a cross-sectional view schematically showing the image forming apparatus,
FIG. 3 is a cross-sectional view schematically showing a process unit, and FIG.
(A) is a front view showing the appearance of the process unit, (b)
FIG. 5 is a side view, and FIG. 5 is an enlarged sectional view showing a photosensitive drum holding portion in the process unit.

The image forming apparatus will be described with reference to FIGS. In this image forming apparatus, a recording paper P stacked on a paper feed cassette 2 provided at an inner bottom portion of the apparatus main body 1 is vertically conveyed upward, and a paper discharge receiver provided at a middle portion of the apparatus main body 1 is provided. It is discharged to the unit 3. Device body 1
Is provided with a mechanism for forming an image on the conveyed recording paper P by electrophotography. In the figure, reference numeral 4 denotes a horizontally disposed process unit, and 5 denotes an exposure device for exposing the photosensitive drum 21 provided in the process unit 4. These process units 4 and the exposure device 5 are located on one side of a recording paper P conveyance path. Is provided. Reference numeral 6 denotes a transfer unit for transferring the toner image formed on the photosensitive drum 21 onto the recording paper P, and 7 denotes a transfer unit 6
The static eliminator removes the electric charges charged on the recording paper P. These static eliminators are provided on the other side of the recording paper conveyance path so as to face the photosensitive drum 21. Reference numeral 8 denotes a thermal fixing unit provided on the upper side of the process unit 4, which fixes the toner image through the recording paper P on which the toner image has been transferred. Further, a feeding roller 9, a transport roller 10, and a registration roller 11 (shown in FIG. 3) for transporting the recording paper P from the paper feed cassette 2 to the process unit 4 are provided below the process unit 4, and are thermally fixed. A discharge roller 12 for discharging the recording paper P on which image formation has been completed to the discharge receiving portion 3 is provided above the container 8.

As shown in FIG. 1, an access port 13 is formed in a vertical front surface of the apparatus main body 1, and the access port 13 is opened and closed by a rotatable door 14. The access port 13 is used to move the process unit 4 in the horizontal direction, that is, the axial direction, and to put the process unit 4 in and out of the apparatus main body 1.

Next, the process unit 4 will be described with reference to FIGS. In this embodiment, the process unit 4 includes a developing device.

The process unit 4 is provided with a unit cover 52 described later as a member for integrating the whole, and each mechanism described later is arranged inside the unit cover 52. A photosensitive member case 43 for holding the photosensitive drum 21 by a holding member 46 is arranged and held inside the unit cover 52.

The process unit 4 has the following mechanism. Reference numeral 21 denotes a horizontally arranged photosensitive drum that forms an image to be transferred onto the recording paper P on the outer peripheral surface, and 22 denotes a charger that is arranged alongside the photosensitive drum 21 and charges the photosensitive drum 21. Reference numeral 23 denotes a developing device disposed below the photosensitive drum 21. The developing device 23 includes a tank 24 for storing toner.
And a developing roller 25 that supplies toner to the photosensitive drum 21 to form a toner image. Further, on the upper side of the photosensitive drum 21, a peeling claw 26 for peeling the recording paper P after the transfer from the photosensitive drum 21, a recovery sheet for preventing the residual toner removed from the photosensitive drum 21 after the transfer from flowing back. 27, a cleaning blade 28 for removing the residual toner from the photosensitive drum 21 after the transfer and a static eliminator 29 for removing the charge remaining on the photosensitive drum 21 after the transfer are arranged.

A photosensitive drum 21, a photosensitive case 43, a holding member 46, and a unit cover 52 are held in combination at both axial ends of the process unit 4. Further, a configuration for positioning the process unit 4 with respect to the apparatus main body 1 is added to an end on the back side when the process unit 4 is loaded into the apparatus main body 1.

A configuration in which the photosensitive drum 21, the photosensitive case 43, the pair of holding members 46, and the unit cover 52 are held in combination at both ends of the process unit 4 will be described with reference to FIGS.

The photosensitive drum 21 is a cylindrical body having both ends opened, and end plates 41 each having a circular shape as an end surface are fitted and fixed to the openings at both ends. Each of the end face plates 41 is formed with a holding hole 42 located on the central axis of the photosensitive drum 21.

The photoconductor case 43 connects a pair of vertical end walls 44 facing each other at an interval longer than the entire length of the photoconductor drum 21 and an upper edge of the pair of end walls 44. It has a horizontal connecting beam 43a. Fitting holes 45 are formed in the pair of end wall portions 44 on the same horizontal line (straight line) connecting them. The fitting hole 45 has a larger diameter than the holding hole 42 of the photosensitive drum 21. Then, the pair of end wall portions 4 in the photoconductor case 43
4, the photosensitive drum 21 is disposed horizontally with its central axis aligned with the horizontal line where each fitting hole 45 is located.

The pair of holding members 46 hold the photosensitive drum 21 in the photosensitive case 43. Here, a cylindrical body fitted in the fitting hole 45 of the pair of end walls 44 in the photosensitive case 43 is used. A first shaft portion 47 to be formed and a cylindrical body located inside the pair of end wall portions 44 with respect to the first shaft portion 47 and inserted into the holding hole 42 of the end face plate 41 of the photoconductor drum 21. The second shaft portion 48 to be formed is integrally formed on the same straight line, and the tip portion of the second shaft portion 48 is sharpened so as to be easily inserted. Further, the second shaft portion 48 is attached to the first shaft portion 47.
An engaging portion 49 is formed on the opposite side from the first shaft portion. Here, the engaging portion 49 is formed by using an internal space in which the base end of the first shaft portion 47 forming a cylindrical body is open. ing. First
A flange portion 50 is formed at the end of the shaft portion 47 on the opposite side to the second shaft portion 48 so as to expand toward the outer peripheral side.

The first shaft portion 47 of the pair of holding members 46 is fitted into the fitting hole 45 from outside the pair of end wall portions 44 of the photosensitive body case 43, and the second shaft portion 48 is formed of a pair of holding members 46. It is inserted from outside into the holding holes 42 of the pair of end face plates 41 of the photosensitive drum 21 disposed inside the end wall portion 44. The flange portions 50 of the pair of holding members 46 are in contact with the outer surfaces of the pair of end wall portions 44, and screws 51 are screwed into holes formed in the flange portions 50 and the end wall portions 44. Thereby, the holding member 46 is fixed to the end wall portion 44. Thus, the photosensitive drum 21 is rotatably supported by the holding member 46, and the holding hole 42 of the photosensitive drum 21 and the fitting hole 45 of the photosensitive case 43 are arranged in a state where they are located on the same horizontal line.

The pair of end walls 4 of the photosensitive body case 43
In addition to the photoconductor drum 21, the charger 22, the peeling claw 26, the recovery sheet 27, the cleaning blade 28, and the static eliminator 29 are arranged between the photoconductor drums 21 and are held by a pair of end walls 43. Each of these mechanisms has a fitting hole 4
5 are set at predetermined positions with reference to the central axis.
For this reason, by holding the photoconductor drum 21 on the same horizontal line as the fitting hole 45 of the photoconductor case 43 by the holding member 46, each of the above-described mechanisms moves the center axis of the photoconductor drum 21 with respect to this center axis. They are arranged with a predetermined positional relationship with respect to them.

The unit cover 52 includes a photosensitive member case 43.
A pair of end plate portions 53 facing each other on a vertical plane with an interval longer than the interval between the pair of end wall portions 44;
It has a horizontal connecting beam portion 52a connecting the upper edges.
The same horizontal line (straight line) connecting these end plates 44
Positioning portions 54 that are located above and protrude inward are formed inward, respectively. The positioning portion 54 engages with the engaging portion 49 of the holding member 46, and is formed in a cylindrical shape here.

When the process unit 4 is inserted into the apparatus main body 1, an end plate 53 (the right end plate in FIG. 4) positioned on the back side (the inner side of the apparatus main body 1) is provided with a positioning section 5
4, a main body positioning portion 55 is formed on the same horizontal line (straight line) as that of FIG. Here, the main body positioning portion 55
Are formed using a circular inner hole of the cylindrical positioning portion 54. Further, the main body positioning portion 55 has a large diameter so that the process unit 4 can be stably positioned with respect to the apparatus main body 1. Therefore, an end plate portion located on the back side (inside of the apparatus main body 1). The positioning portion 54 formed on the end plate portion 53 is located on the outside.
Is formed to have a larger diameter than the positioning portion 54 formed at the bottom.

The photosensitive drum 21 and the photosensitive case 43 are horizontally arranged between the pair of end plates 53 of the unit cover 52 such that the central axes of the photosensitive drum 21 and the photosensitive case 43 coincide with the horizontal line on which the positioning portion 54 is located. You. Positioning portions 54 formed on the pair of end plate portions 53 of the unit cover 52 are engaged with engaging portions 49 of the holding member 46 fitted into the fitting holes 45 of the pair of end wall portions 44 of the photoconductor case 43 from outside. Engage. As a result, the photosensitive member case 43 is moved to the positioning portion 5.
4 and the holding member 46 hold the unit cover 52 so that the fitting hole 45 is located on the same horizontal line as the positioning portion 54.

The developing unit 23 is disposed between the pair of end plates 53 of the unit cover 52 and is held by the pair of end plates 53.

As described above, in the process unit 4, the photosensitive body case 43 and the unit cover 52 are combined with each other with respect to the center axis O of the photosensitive drum 21. Developing device 2
Reference numeral 3 is set at a predetermined position based on the center axis of the positioning portion 54 of the unit cover 52. For this reason, the photosensitive member case 43 and the photosensitive drum 21 are
Is held on the same horizontal line by the
Can be arranged with high precision at a position having a predetermined positional relationship required for the photosensitive drum 21. That is, the central axis of the photosensitive drum 21 and the developing unit 23 can be directly set in a positional relationship with each other, and can be set in a positional relationship with required level accuracy. Further, a main body positioning portion 55 formed integrally with the positioning portion 54 of the unit cover 52 is also positioned on the center axis of the photosensitive drum 21.

In the process unit 4, the unit cover 52 is attached to the photosensitive drum 2 via the holding member 46.
1, the charger 22 held by the unit cover and the center axis of the photosensitive drum,
The positional relationship between the peeling claw 26, the recovery sheet 27, the cleaning blade 28, and the mechanism of the static eliminator 29 can be set with reference to the center axis of the photosensitive drum 21, and the center axis of the photosensitive drum 21 and these mechanisms can be set. And the accuracy of the required level setting can be secured.

On the other hand, in the apparatus main body 1, a unit cover serving as a rear end of the process unit 4 loaded inside the apparatus main body 1 is provided on an inner surface of a rear surface portion facing the front surface portion where the access port 13 is formed. A main body positioning member 56 is provided at the same horizontal line where the main body positioning portion 55 formed on the end face 53 of the main body 52 is located. The main body positioning member 56 has a cylindrical pin shape to be inserted into the main body positioning portion 55 formed of an inner hole of the positioning portion 54 of the end plate portion 53. That is, the main body side positioning member 5
Reference numeral 6 is provided at a position where the process unit 4 is inserted into the main body positioning portion 55 when the process unit 4 is loaded at a predetermined loading position inside the apparatus main body 1.

Then, the process unit 4 is connected to the apparatus main body 1.
In order to load the inside of the apparatus main body 1, the end where the main body positioning portion 55 is located is located at the back side and is moved in the horizontal direction (axial direction). It is inserted into the main body 1 and loaded in a predetermined manner. Here, the main body positioning member 55 provided on the inner surface of the rear surface portion of the apparatus body 1 which is provided on the main body positioning portion 55 formed on the end surface portion 53 of the unit cover 52 located on the rear end of the process unit 4. 56 is inserted.

As a result, the process unit 4 is positioned at a predetermined loading position inside the apparatus main body 1. In this case, the process unit 4 is mounted on the apparatus main body 1 with the center axis of the photosensitive drum 21 as a reference because the main body positioning portion 55 is located on the center axis of the photosensitive drum 21. In the apparatus main body 1, the transfer unit 6 and the heat fixing unit 8 are provided with their positions set with reference to the main body side positioning member 56. For this reason, the process unit 4
The photosensitive drum 21 can be arranged at an accurate position having a predetermined positional relationship with respect to each of the mechanisms such as the transfer device 6 and the fixing device 8 provided in the apparatus main body 1 by mounting the image forming apparatus.

By positioning the apparatus main body 1 on the center axis of the photosensitive drum 21 via the unit cover 52 of the process unit 4 and the holding member 46 in this way, the center axis of the photosensitive drum 21 and the apparatus main body 1 are aligned. The positional relationship with the mechanism to be provided can be set with reference to the center axis of the photosensitive drum 21, and the level setting required between the center axis of the photosensitive drum 21 and the mechanism provided in the apparatus main body 1 can be set. Accuracy can be ensured.

The present invention is not limited to the above-described embodiment, but can be implemented in various modifications.

[0040]

According to the process unit of the present invention, the unit cover is disposed on the center axis of the photosensitive drum via the holding member, so that the unit cover is held by the center axis of the photosensitive drum and the unit cover. The positional relationship with the mechanism such as the developing unit can be set based on the center axis of the photosensitive drum, and the position between the center axis of the photosensitive drum and the mechanism such as the developing unit can be set with the required level of accuracy. Setting can be performed to perform good image formation.

According to the second aspect of the present invention, the apparatus main body is positioned on the central axis of the photosensitive drum via the unit cover and the holding member of the process unit.
The positional relationship between the center axis of the photoconductor drum and the mechanism provided in the apparatus main body can be set with reference to the center axis of the photoconductor drum, which is necessary between the center axis of the photoconductor drum and the mechanism provided in the apparatus main body. The position can be set with the level accuracy described above, and good image formation can be performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing the image forming apparatus according to the embodiment.

FIG. 3 is a sectional view schematically showing a process unit in the embodiment.

FIG. 4 is a front view showing the appearance of the process unit in the embodiment.

FIG. 5 is an enlarged sectional view showing a photosensitive drum holding portion in the process unit according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Device main body 4 ... Process unit 8 ... Thermal fixing device 12 ... Access port 21 ... Photoconductor drum 23 ... Developing device 30 ... Transfer device 41 ... End surface part 42 ... Holding hole 43 ... Photoconductor case 44 ... End wall part 45 ... Fitting hole 46 ... Holding member 47 ... First shaft part 48 ... Second shaft part 49 ... Engagement part 52 ... Unit cover 53 ... End plate part 54 ... Positioning part 55 ... Body positioning part 56 ... Body side positioning Element

Claims (2)

[Claims] 1. A photosensitive drum having a pair of end surfaces formed with a holding hole positioned on a central axis, and a pair of end wall portions facing each other at an interval. A photoreceptor case in which a fitting hole located on the same straight line is formed, and the photosensitive drum is arranged on the straight line where the fitting holes are located between the pair of end walls; A first shaft fitted into the fitting hole of the pair of end walls in the photosensitive body case, and the photosensitive drum positioned inside the pair of end walls with respect to the first shaft; A second shaft portion inserted into the holding hole of the end surface portion is integrally formed on the same straight line, and the first shaft portion is located on the opposite side to the second shaft portion, and an engaging portion is formed. A pair of holding members formed, and a pair of end plate portions facing each other at an interval, and a straight line connecting these to the pair of end plate portions. The photosensitive body case is disposed on the straight line on which the positioning part is formed and the respective positioning parts are located between the pair of end plate parts, and the positioning part is a fitting hole of the photosensitive body case. A unit cover engaged with an engaging portion of the holding member fitted to the process unit. 2. The process unit according to claim 1, wherein:
A transfer unit provided in the process unit for transferring the toner image of the photosensitive drum onto recording paper; and a transfer unit which is internally provided with the process unit and the transfer unit, and moves the process unit in and out along the axial direction thereof. A device main body having a mouth, wherein the main body positioning portion is formed on the unit cover provided in the process unit on a straight line where the positioning portion is located, and the device is opposed to the access port. On the inner surface of the wall of the main body, a main body side positioning member that engages with the main body positioning portion of the unit cover provided on the process unit when the process unit is loaded into the inside of the apparatus main body from the access port. An image forming apparatus, which is provided.