JPH05119682A - Photosensitive drum - Google Patents

Abstract

PURPOSE:To surely ground a drum by forming a grounding plate of a shape memory alloy and forming a contact part to be restored to a shape in contact with a bearing or drum shaft at the time of using the drum on this grounding plate. CONSTITUTION:The grounding plate 28 made of the shape memory alloy to ground the drum 16 by electrically conducting the drum 16 to the drum shaft 22 side is provided. The contact part to be restored to the shape in contact with the bearing 20 or the drum shaft 22 at a prescribed temp. is formed on this grounding plate 28. The contact part of the grounding plate 28 is a pawl part 28C to be press fitted to the bearing 20 of a flange 18 and is so formed that this pawl part 28C is restored to the shape in contact with the bearing at the environmental use at the time of using the drum. Pawl parts 28E to be pressed fitted to the outer peripheral surface part of the flange 18 are formed on the grounding plate 28 in such a manner that these pawl parts 28E come into contact with the inside surface of the drum 16 at the time of press fitting the outer peripheral surface part of the flange 18 to the drum end. Then, the pawl parts 28C and 28E are eventually surely electrically conducted to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive drum used in an image forming apparatus such as an electronic copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, for example, a digital color electronic copying machine is constructed as shown in FIG. 6, and a color original placed on a contact glass 1 so as to be pressed by an original pressing member 2 constitutes a color scanner. Scanned by the scanning optical system, the image information is guided from the condenser lens 3 to the light receiving element 4 such as CCD using light as a medium, converted into an electric signal there, and then subjected to signal processing by the image processing circuit 5. After that, the laser beam output from the laser scanner unit 6 based on the respective color image data is drawn as a latent image on the photosensitive drum 7. Prior to this, the photosensitive drum 7
The surface of is charged uniformly by the main charger 8. Here, 9, 10, 11, and 12 have yellow, magenta, cyan, and black toners, respectively, and the photoconductor drum 7 is alternatively selected corresponding to latent image writing by laser beam output based on each color image data. And a developing device 13 for developing each latent image with toner of each color, which is brought to a developing position facing each other, and 13 is each developing device 9, 10, 11, 1
2 is a transfer drum for sequentially transferring each image on the photoconductor drum 7 developed and formed on the sheet to a sheet, and 14 is a sheet for separating the sheet on which the color image is formed from the transfer drum 13 and conveying the sheet to the fixing unit. A transport unit, 15 is each developing device 9, 1
A cleaning unit and a discharging unit (not shown) for wiping off and removing the residual toner on the photosensitive drum 7 each time the development by 0, 11, and 12 and the transfer by the transfer drum 13 are performed.

The photosensitive drum 7 which plays an important role in such image formation is constructed as shown in FIGS. 7 and 8, and 16 is selenium, an organic photo-semiconductor cadmium sulfide or the like on the surface thereof. Cylindrical aluminum drum 18 or 19 on which the photosensitive layer 17 is formed by vapor deposition or coating.
The outer peripheral surface portions 18A of the drum 16 at both open ends,
19A is a disc-shaped resin flange into which each is press-fitted, and a shaft portion 18B of one flange 18 is insert-molded with a bearing 20 of a copper sintered oil-impregnated type, and a shaft portion 19B of the other flange 19 is formed. Has an insertion hole 21 formed in a shape that is combined with one end of a drum shaft (described later) to be inserted and integrally rotates. Reference numeral 22 denotes a metal drum shaft that is inserted into the bearing 20 of the one flange 18 from one end side thereof and is inserted into the insertion hole 21 of the other flange 19, and is integrated with the insertion hole 21 at one end side thereof. A flat surface 22A is formed so as to rotate in the same direction, and a drive pulley (not shown) is fixed to the flat surface 22A.
A knob 23 used for inserting the drum shaft 22 is fixed to the other end side, and is rotatably supported by support plates 24 in the main body of the copying machine at both end sides thereof. There is. Reference numeral 25 denotes a ground plate (for example, a stainless plate) that is press-fitted into one flange 18 to electrically connect the drum 16 and the drum shaft 22 and ground the drum 16 through the drum shaft 22. Is formed with through holes 25A and 25B for inserting the bearing 20 and the retaining rib 18C of the flange 18, and the bearing 20, the retaining rib 18C, and the outer peripheral surface portion 18A at the hole edge portion and the outer peripheral edge portion. Claws 2 that are pressed into
5C, 25D, and 25E are integrally formed, and the claw portion 25E at the outer peripheral edge portion thereof makes contact with the inner surface of the drum 16 while scraping off the oxide film when press-fitting into the end portion of the drum 16 of the flange outer peripheral surface portion 18A. Is becoming

Therefore, the photosensitive drum 7 having such a structure
At the open end of the drum 16 are flanges 18, 19 respectively.
After that, the drum shaft 22 is inserted from one end side thereof into the bearing 26 of the support plate 24 → the bearing 20 of the flange 18 → the through hole 21 of the flange 19 → the bearing of the support plate (not shown), and the one end side thereof is inserted. By fixing the drive pulley to the disk, it can be rotatably incorporated into the main body of the copying machine (see FIG. 9). Then, in this state, when the rotational driving force from the driving source is transmitted to the driving pulley via the belt or the like by the copy operation, the drum 16 is rotationally driven from the drum shaft 22 via the flange 19. Drum 1 at this time
6 is always grounded to the metal frame in the main body of the copying machine through the claw portions 25E and 25C of the grounding plate 25 → the bearing 20 → the drum shaft 22 and the grounding contact piece 27 in contact with the drum shaft 22. There is.

[0005]

However, in the photoconductor drum 7 having such a conventional structure, the flange 18 made of resin is used.
The claw portions 25E and 25C of the ground plate 25, which are press-fitted into the drum 1, are brought into contact with the drum 16 and the bearing 20, respectively.
6 and the drum shaft 22 are electrically connected to each other, therefore, when the drum shaft 22 is inserted into the bearing 20 of the flange 18, an unreasonable force is applied to the bearing 20 so that the flange 1
When 8 is deformed (so-called elastic deformation), the claw portion 25C press-fitted into the bearing 20 is plastically deformed by the bearing 20,
That is, there is a problem that it is pushed out and does not come into contact with the peripheral surface of the bearing 20, resulting in poor conduction between the ground plate 25 and the bearing 20. As a result, the drum 16 may be grounded poorly, for example, an image defect may occur due to insufficient removal of the charged charges of the photosensitive layer during latent image formation by laser beam output, or sudden grounding may occur. A large current flows through the ground path to generate a high voltage, and the high voltage similarly grounds the frame (for example, used for signal processing in the image processing circuit 5 or control of the copying machine main body). There is a possibility that the data may be erased or destroyed by being instantaneously applied to RAM). The present invention has been made in view of the above circumstances, and an object thereof is to provide a photosensitive drum in which the grounding of the drum by the grounding plate is surely performed.

[0006]

According to the present invention for achieving the above object, a metal drum having a photosensitive layer formed on the surface thereof and a resin flange press-fitted to the end of the drum are provided. And a metal drum shaft inserted into the bearing of the flange, a ground plate made of a shape memory alloy for grounding the drum by electrically connecting the drum to the drum shaft side. The ground plate is provided with a contact portion that is restored to a shape in contact with the bearing or the drum shaft at a predetermined temperature. Specifically, the contact portion of the ground plate is the bearing of the flange. The claw portion is press-fitted, and the claw portion is restored to the shape in contact with the bearing at the ambient temperature when the drum is used. Further, the earth plate is provided with a claw portion press-fitted to the outer peripheral surface portion of the flange, and the claw portion comes into contact with the inner surface of the drum when press-fitted to the drum end portion of the flange outer peripheral surface portion. is there.

[0007]

With this structure, when the drum shaft is inserted into the flange bearing, an unreasonable force is applied to the bearing,
Even if the claw part press-fitted into the bearing deforms and comes off the peripheral surface, the deformed claw part will be restored to the original shape in contact with the bearing at the ambient temperature when the drum is used. The electrical conduction between the bearing and the bearing is ensured.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the photosensitive drum of the present invention will be described below with reference to the drawings. The same parts as those of the conventional one are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, a shape memory alloy ground plate is used for electrical conduction between the drum and the drum shaft via the bearing, and the ground plate is restored to a shape in contact with the bearing at a predetermined temperature. The contact part is formed. Specifically, the ground plate 28 made of the shape memory alloy shown in FIG.
Through holes 28A, 28B for inserting the bearing 20 and the retaining rib 18C of the flange 18 are formed, and the bearing 20, the retaining rib 18C, and the outer peripheral surface portion 18A are formed in the hole edge portion and the outer peripheral edge portion. Claws 28 that are press-fitted respectively
C, 28D and 28E are integrally formed in a bent shape as shown by the solid line in FIG. 2, and these claw portions 28C, 28D,
28E is a predetermined temperature even if it is deformed, in this case, the ambient temperature when the drum is used (that is, the temperature generated by the color scanner, the laser scanner unit, the fixing unit, etc.
The original solid line shape is restored at an internal temperature of the copying machine (° to 50 °). Therefore, when these claw portions 28C, 28D, and 28E are pressed into the flange 18 side while being deformed from the solid line shape in FIG. 2 to the dotted line shape, the deformed claw portions 28C, 28D, and 28E are the original at the ambient temperature when the drum is used. In order to return to the solid line shape, the bearing 20, the retaining rib 18C, and the outer peripheral surface portion 18A respectively bite.

Therefore, when the ground plate 28 made of the shape memory alloy having such a structure is used, when the drum shaft 22 is inserted into the bearing 20 of the flange 18 as shown in FIG. The flange 18 is deformed by applying an unreasonable force, and the claw portion 2 is press-fitted into the bearing 20.
Even if 8C (the position indicated by the alternate long and short dash line in FIG. 4) is expanded by the bearing 20 so that it does not come into contact with the circumferential surface of the bearing 20 (even if it is deformed to the position indicated by the solid line in FIG. 4), the ambient temperature during use of the drum after insertion causes Original shape on the claw portion 28C (position indicated by the dotted line in FIG. 4)
The force of returning to the bearing 20 acts to restore the shape (the position indicated by the alternate long and short dash line in FIG. 4) in contact with the circumferential surface of the bearing 20. still,
At the ambient temperature when the drum is used, the other claw portions 28D and 28E also try to return to their original shapes and bite into the retaining ribs 18C and the outer peripheral surface portion 18A, respectively. At this time, the claw portions 28E at the outer peripheral edge portion are flanged. When the outer peripheral surface portion 18A is press-fitted into the end portion of the drum 16, the outer peripheral surface portion 18A is sandwiched between the tapered inner surface of the end portion of the drum 16 and the tapered outer peripheral surface portion 18A of the flange 18 to scrape and contact the inner surface of the drum 16 and its oxide film. Therefore, the electrical conduction between the drum 16 and the ground plate 28 is maintained in a good state with almost no influence thereof. Therefore, stable and good electrical continuity can be always obtained between the bearing 20 and the claw portion 28C and between the drum 16 and the claw portion 28E, and the ground of the drum 16 is the claw portions 28E and 28C of the earth plate 28 → the bearing. 20 →
This is surely done through the drum shaft 22 and the ground contact piece 27.

In this embodiment, the drum 16 and the drum shaft 2 are
2 and the drum shaft 22 are rotated together.
May be fixed and only the drum 16 may be rotated. In that case, a driving shaft portion may be formed on the flange 19 side to drive the drum 16. Further, in this embodiment, the bearing 16 and the claw portion 28C press-fitted thereto are used to electrically connect the drum 16 to the drum shaft 22 side. However, the contact piece that directly contacts the drum shaft 22 is a ground plate. Alternatively, the grounding plate may be press-fitted to the other flange 19 side for grounding. For example, as shown in FIG. 5, the earth plate 28 in which the contact piece 28F is formed instead of the claw portion 28C at the hole edge portion of the through hole 28A is press-fitted to the flange 19 side where the slip-off preventing rib 19C is formed. At that time, in order to facilitate the insertion of the drum shaft 22, the contact piece 28F is previously attached to the drum shaft 2.
It may be deformed outside the insertion passage (solid line position) of No. 2 and restored to a shape (dotted line position) in contact with the drum shaft 22 at the environmental temperature when the drum is used after insertion. And
When the drum shaft 22 is fixed and only the drum 16 is rotated, sliding contact friction with the drum shaft 22 can be reduced by forming the contact portion 28G in an arc shape.

[0011]

As described above, according to the photoconductor drum of the present invention, the ground plate is made of a shape memory alloy, and the ground plate is restored to the shape in contact with the bearing or the drum shaft at the ambient temperature when the drum is used. Since the contact portion is formed, the electrical conductivity of the bearing or the drum shaft portion can be improved and the drum can be reliably grounded.

[Brief description of drawings]

FIG. 1 is a diagram showing a ground plate of the present invention.

FIG. 2 is a diagram showing a process of press-fitting the ground plate.

FIG. 3 is a diagram showing a process of assembling a photosensitive drum using the ground plate.

FIG. 4 is an enlarged view of a main part thereof.

FIG. 5 is a diagram showing another embodiment.

FIG. 6 is a diagram showing a configuration example of a conventional copying machine.

FIG. 7 is an exploded perspective view of the photosensitive drum.

FIG. 8 is a perspective view showing a press-fitting process of the ground plate.

FIG. 9 is a cross-sectional view in the assembled state.

[Explanation of symbols]

 7 Photoreceptor Drum 16 Drum 18, 19 Flange 22 Drum Shaft 28 Ground Plate 28C, 28D, 28E Claw

Claims (3)

[Claims] 1. A metal drum having a photosensitive layer formed on a surface thereof, a resin flange press-fitted into an end portion of the drum, and a metal drum shaft inserted into a bearing of the flange. The photoconductor drum is provided with a grounding plate made of a shape memory alloy that electrically connects the drum to the drum shaft side to ground the drum. The grounding plate has a shape that contacts the bearing or the drum shaft at a predetermined temperature. A photoconductor drum having a contact portion to be restored to. 2. The contact portion of the ground plate is a pawl portion press-fitted into the bearing of the flange, and the pawl portion is restored to a shape in contact with the bearing at an ambient temperature when the drum is used. The photosensitive drum according to claim 1. 3. The earth plate is formed with a claw portion press-fitted to the outer peripheral surface portion of the flange, and the claw portion contacts the inner surface of the drum when press-fitted to the drum end portion of the flange outer peripheral surface portion. The photosensitive drum according to claim 2, which is characterized in that.