JP3367217B2 - Electrophotographic photosensitive drum device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a photosensitive drum device used in an electrophotographic copying machine, a printer (including a printer unit incorporated in a facsimile) or the like.

[0002]

2. Description of the Related Art A photosensitive drum in the above-mentioned electrophotographic photosensitive drum device is rotatably supported on a drum shaft fixed to a device frame and has a photoconductive layer on the surface side. Due to its function, the photoconductive layer must be grounded, and conventionally, the photoconductive layer is grounded by the method shown in FIG. That is, in FIG. 3, the drum shaft a is fixed to the device frame (made of metal) b, and the photosensitive drum c is connected to the drum shaft a via the insulating flange members d fitted to both ends thereof.
It is rotatably supported by. A ground terminal e is fixed to the inner surface of the photosensitive drum c in a conductive state with the photoconductive layer, and the tip of the ground terminal e is disposed so as to contact the peripheral surface of the drum shaft a. Earth terminal e as the photosensitive drum rotates
Of the photoconductive layer comes into sliding contact with the drum shaft a, and as a result, the photoconductive layer is grounded via the ground terminal e, the drum shaft a and the device frame b. The photosensitive drum c rotates about the drum shaft a by transmitting the rotational power from a drive mechanism (not shown) provided in the apparatus to the gear portion d1 provided on the flange member d.

[0003]

In the ground connection method as described above, noise is often generated at the sliding contact between the ground terminal e and the drum shaft a, and the user often feels uncomfortable. In order to prevent the generation of abnormal noise, a lubricant such as grease is applied to the sliding contact position. However, when the drum shaft a coated with grease is inserted into the photosensitive drum c for assembly, the grease may protrude to the outside of the flange member d, which may adhere to the surface of the photosensitive drum and hinder image formation. It was It is also expected to accelerate the deterioration of the photoconductive layer. Further, there is a problem that the grease diffuses on the surface of the drum shaft a with the lapse of time, and the effect of preventing abnormal noise decreases.

The present invention has been made in view of the above,
An object of the present invention is to provide a novel electrophotographic photosensitive drum device that suppresses the generation of abnormal noise, does not cause image formation trouble, and has a long-lasting effect of preventing abnormal noise.

[0005]

In order to achieve the above object, the electrophotographic photosensitive drum device of the present invention is electrically connected to the photoconductive layer in the electrophotographic photosensitive drum device as described above. The tip of the ground terminal is provided so as to be in sliding contact with the small diameter portion formed on the drum shaft. Then, in the photosensitive drum device of the present invention, a lubricant such as grease is applied to the small diameter portion before assembly.

[0006]

In the photosensitive drum device having the above structure, the photosensitive drum is rotated around the drum shaft by receiving the power from the driving means in the device. At this time, the ground terminal rotates by sliding on the peripheral surface of the small diameter portion. Therefore, the photoconductive layer of the photosensitive drum is grounded via the ground terminal and the drum shaft. And since a lubricant such as grease is applied to the small diameter portion,
Generation of abnormal noise due to sliding contact is suppressed. The lubricant applied to the small diameter portion does not stick out even when the drum is assembled, does not adhere to the surface of the drum, and there is no fear of image formation failure. Further, even during long-time operation, the lubricant does not overflow from the small diameter portion and does not diffuse on the drum shaft surface, so that the noise preventing effect is maintained for a long time.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic vertical sectional view of an image forming apparatus using a photosensitive drum device of the present invention, and FIG. 2 is a partially cutaway vertical sectional view of the photosensitive drum. In FIG. 1, reference numeral 1 is a photosensitive drum, which is supported by a drum shaft 2 and rotates in the direction of the arrow. Around the photosensitive drum, a charger 10, an optical writing unit 11,
Developing device 12, transfer device 13 and cleaning unit 14
Etc. are arranged. In this embodiment, the positioning portions of the photosensitive drum 1, the drum shaft 2, the charger 13, the cleaning unit 14, and the optical writing unit 11 are integrally unitized as a drum unit, and these are incorporated in the housing case 20. Also,
A paper feed cassette 15 for accumulating and holding recording paper P, a pickup roller 16, a paper guide portion 17, and a registration roller 18 are arranged on the upstream side of the process means including the photosensitive drum 1, and a fixing device 19 and a discharge roller are provided on the downstream side. The roller 20 and the recording paper discharge tray 21 are sequentially arranged.

The operation of the image forming apparatus having the above configuration will be briefly described. The surface of the photosensitive drum 1 rotating in the direction of the arrow is uniformly charged by the charger 10, and image information is written on the uniformly charged surface of the photosensitive drum 1 by the optical writing unit 11 including an LED array or the like. Electrostatic latent image is formed. This electrostatic latent image is visualized by the developing device 12. On the other hand, the recording paper P is fed one by one from the paper feed cassette 15 by the pickup roller 16, and the recording paper P is transferred to the photosensitive drum 1 in synchronization with the rotation of the photosensitive drum 1 by the registration roller 18 via the paper guide portion 17. Is supplied to the container 13. The toner image visualized on the surface of the photosensitive drum 1 reaches the transfer device 13 as the drum 1 rotates, and is transferred onto the recording paper P by the transfer device 13. The toner image transferred onto the recording paper P is fixed by the fixing device 19 to be a permanent image. The fixed recording paper P is discharged onto the recording paper discharge tray 21 by the discharge roller 20 and accumulated.

FIG. 2 shows details of the installed state of the photosensitive drum. The drum shaft 2 made of conductive metal is non-rotatably supported by the housing case 20, and the portion protruding from the housing case 20 is made of conductive metal ( It is supported and positioned by the device frames 3 and 3 made of sheet metal. The photosensitive drum 1 is a conductive metal cylinder 1a such as aluminum.
And a photoconductive layer 1b coated on the outer periphery of the cylindrical body 1a, and an insulating protective layer 1c made of a transparent resin and coated on the outer periphery of the photoconductive layer 1b. Flange members 4 and 4 formed of an insulating resin are fitted and fixed to both ends of the photosensitive drum 1, and one of the flange members 4 is formed with a gear portion 4a which meshes with a rotation driving mechanism (not shown). . On the other flange member, a gear portion 4b for transmitting the rotation of the photosensitive drum 1 to a guide roller 13a (see FIG. 1) for feeding and guiding the recording paper to the transfer device 13 is formed. The flange member 4 also functions as a bearing in which the drum shaft 2 is inserted into the shaft hole 4c and which rotatably supports the photosensitive drum 1 around the drum shaft 2.

A ground terminal 5 made of a conductive metal plate having a spring property is fixed to the inner end surface of one flange member 4. More specifically, the ground terminal 5 is formed by punching a thin copper plate to form a primary-side contact piece 5a that comes into pressure contact with the cylindrical body 1a side of the photosensitive drum 1 and a secondary-side contact piece 5b that comes into sliding contact with the drum shaft 2. It was obtained by bending. And
A small hole 5c is bored in the base of the earth terminal 5, and a small protrusion 4d protruding from the inner end surface of the flange member 4 is inserted into the small hole 5c and heat-bonded (or caulked) to the earth terminal. 5 is fixed to the inner end surface of the flange member 4.

A small-diameter portion 2a is formed by cutting on the sliding contact portion of the contact piece 5b of the drum shaft 2. It is desirable that the thrust direction opening width of the small diameter portion 2a is a width in which the contact piece 5b can be fitted and is shorter than the thrust direction length of the shaft hole 4c of the flange member 4.

An assembling procedure of the photosensitive drum 1 and the drum shaft 2 having the above-mentioned construction will be described. First, a lubricant 2b such as grease is applied to the small diameter portion 2a of the drum shaft 2 so as not to exceed the large diameter portion of the drum shaft 2. The drum shaft 2 is inserted into the shaft holes 4c and 4c of the flange members 4 and 4 and the contact piece 5b.
Is inserted into the small diameter portion 2a so that the drum shaft 2 is fixed to the housing case 20 to form a drum unit. In this state, the contact piece 5b is pressed against the small diameter portion 2a due to its spring property, and the other contact piece 5a is pressed against the inner surface of the cylindrical body 1a of the photosensitive drum 1. Further, the grease 2b applied to the small diameter portion 2a is accommodated in the recess formed by the small diameter portion 2a, and the opening width in the thrust direction of the small diameter portion 2a is the axial hole 4c.
Since the inner wall of the shaft hole 4c does not fall into the small-diameter portion 2a because it is shorter than the length of the shaft, it does not protrude to the outside of the flange members 4 and 4 when the drum shaft 2 is inserted. The drum unit thus assembled is installed in the apparatus by horizontally positioning the drum shaft 2 on the apparatus frames 3 and 3. As a result, the photoconductive layer 1b of the photosensitive drum 1 is grounded to the outside of the device via the cylindrical body 1b, the ground terminal 5, the drum shaft 2 and the device frame 3. Further, in this assembled state, the gear portion 4a formed on the flange member 4 meshes with the rotary drive mechanism installed in the apparatus, and the other gear portion 4b meshes with the transmission gear (not shown) of the guide roller 13a. It is installed in the position.

In the drum unit incorporated as described above, the photosensitive drum 1 is driven by the rotary power of the rotary drive mechanism.
Rotates around the drum shaft 2. At this time, the contact piece 5b of the ground terminal 5 makes sliding contact with the peripheral body of the small diameter portion 2a. The small diameter part 2
Since the grease 2b is applied to a, the sliding contact noise is alleviated and the generation of abnormal noise is suppressed. Further, since the grease 2b is housed in the recess formed by the small diameter portion 2a, the grease 2b does not diffuse on the surface of the drum shaft 2 even if the rotational drive continues for a long time, and the noise suppressing effect is maintained for a long time. If a conductive grease is used as the grease 2b, the conductivity at the contact portion will not be impaired, so it is preferably adopted.

FIG. 1 shows a facsimile machine equipped with the image forming apparatus as a printer section.
Although the description is omitted, in addition to the above, an image reading unit, a document conveying system, a control unit and the like are provided. It goes without saying that the present invention is not limited to such a facsimile machine, but is also applicable to so-called printers, copiers, and the like.

[0015]

As described above, according to the present invention, by applying the lubricant to the small diameter portion of the drum shaft, the suppression of the abnormal noise caused by the rotation of the photosensitive drum can be maintained for a long time, and the image can be formed by the lubricant. There is no concern that formation disorders will occur, and its usefulness is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of an image forming apparatus using a photosensitive drum device of the present invention.

FIG. 2 is a partial cutaway vertical sectional view showing an embodiment of a photosensitive drum device of the present invention.

FIG. 3 is a vertical cross-sectional view of a conventional photosensitive drum device.

[Explanation of symbols]

1 photosensitive drum 1a cylinder 1b Photoconductive layer 1c protective layer 2 drum shaft 2a small diameter part 2b Lubricant 3 device frame 4 Flange member 5 ground terminal

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 21/00 350 G03G 15/00 550 H01R 4/64

Claims (2)

(57) [Claims] 1. An electrophotographic apparatus in which a cylindrical photosensitive drum is rotatably supported on a conductive drum shaft having a small diameter portion, and a photoconductive layer on the surface side of the photosensitive drum is grounded via the drum shaft. A photosensitive drum device, wherein a lubricant applied to a small diameter portion of the drum shaft so as not to exceed a large diameter portion, a ground terminal for electrically connecting the photosensitive drum and the drum shaft, and an end portion of the photosensitive drum. A flange member that is fitted and pivotally supports the drum shaft, wherein the ground terminal has a base portion fixed to an inner end surface of the flange member, a primary-side contact piece that is in pressure contact with the inner surface of the photosensitive drum, and a small diameter portion of the drum shaft. The secondary side contact piece that is elastically slidably contacted with the second side is provided, and the opening width in the thrust direction of the small diameter portion of the drum shaft is shorter than the thrust direction length of the shaft hole through which the drum shaft of the flange member is inserted. Electrophotographic photosensitive drum Location. 2. The electrophotographic photosensitive drum device according to claim 1, wherein the opening width in the thrust direction of the small diameter portion is a width in which the secondary side contact piece can be fitted.