JP2886393B2 - Rotating electrode for photosensitive drum in electrophotographic process - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating electrode for a photosensitive drum in an electrophotographic process, and more particularly to an improvement in a rotating electrode for a photosensitive drum used in an image forming process in electrophotography.

[0002]

2. Description of the Related Art As is well known, there have already been many proposals for copying machines, and in particular, in recent years, electrophotographic copying machines have become the mainstream. The basic configuration of such an apparatus is as follows: a photosensitive drum / charger / exposure device / developer / transfer device /
A series of electrophotographic processes are performed with a static eliminator / cleaner disposed around the photosensitive drum, and the copy paper is discharged via a paper cassette / transfer unit / separator / fixer as a path for the copy paper.

FIG. 7 is an explanatory view of a main portion showing an example of the configuration of such an electrophotographic process. FIG. 7 particularly shows an example of a typical laser printer. In FIG. 1, reference numeral 31 denotes a photosensitive drum, which is usually an organic photoconductor.
Because of the use of OPC drums, many are called OPC drums. A charging device 32, an exposing device 33 using a semiconductor laser or the like, a developing device 34 having a magnetic roller 34b and a toner tank 34a, a transfer device 35, and a peeling device are rotated clockwise from about 12:00 around the photosensitive drum 31. The vessel 36 and the cleaner 37 are arranged. On the other hand, a fixing unit 38 for fixing the sheet on which the toner image has been transferred by the transfer unit 35 and the peeling unit 36 via a switch 37 for detecting the sheet from the sheet cassette 40 includes an upper heat roller 38a and a lower heat roller 38b. And heater lamp 3
8c, and is configured to be discharged to the paper discharge side 41.

The means for forming an image by the apparatus having the structure shown in FIG. 7 as described above can be carried out by a conventional method, and therefore the description thereof is omitted. As shown in FIG. 8, the structure of the drum is usually composed of a three-layer structure. In the figure, reference numeral 53 denotes a metal cylinder (drum) having a wall thickness capable of maintaining a certain strength and rigidity, and usually aluminum is often used. Next, a reference numeral 52 denotes a thickness of 0.2 to 0.1 mm provided on the surface of the metal drum 53.
The pigment layer is about 3 μm. Finally, an OPC layer is provided on the outermost layer surface as a photoreceptor layer 51 with a thickness of about 20 μm.

[0005]

By the way, in the laser printer as exemplified above in FIG. 7, during the printing process, the charger 32 is applied to the photosensitive layer 51 on the surface of the OPC photosensitive drum 31. It is charged to about -560 V by corona discharge of about -6.2 KV. FIG.
Fig. 2 shows the electric circuit diagram. As seen in FIG.
The corona discharge 102 caused by the current C flowing in the direction of the arrow from the 2 KV high-voltage power supply unit 101 is stabilized by a scorotron charger 103 so that the photoconductor (OP)
C) To stabilize the potential of the surface of the drum 31 at -560V. However, due to its structure, the OPC drum 31 needs to rotate in the rotation direction R in synchronization with the travel of the printing paper, so that the portion A in FIG.
2 has to be used, and such a configuration has been conventionally employed.

FIG. 10 shows a conventional photosensitive drum 31.
3 is a cross-sectional view showing a configuration example near the contact point of FIG.
Is a rotating shaft of the photosensitive drum 31 and the other end is fixed to the copying machine main body, but one end is sharpened, and the tip is supported by a bearing 63 as a frictional contact 62 and is in contact with a contact fitting 64. doing. The contact fitting 64 has one end contact portion 65 connected to the inner wall of the photosensitive drum 31, and the frictional contact 62 of the rotating shaft 61 makes point contact with the contact fitting 64, thereby electrically connecting the photosensitive drum 31. Conduction is taking place. Since the friction contact is a point contact, the contact area is small and the contact resistance is high. In addition, there is a possibility that a contact failure may occur as the contact portion wears.

In such a case, if the friction contact 62 at the point A in FIG. 9 causes a contact failure, the current C becomes non-uniform, and the charging voltage on the surface of the photosensitive drum 31 becomes non-uniform. As a result, print quality is adversely affected. On the other hand, the high-voltage power supply unit 101 operates abnormally, and noise, that is, a noise radio wave is generated from the high-voltage power supply unit 101 and the frictional contact 62, and as a result, it causes radio interference (EMI) and thus may be subject to radio regulation. May occur. Accordingly, an object of the present invention is to increase the contact area of the rotating electrode, thereby reducing the change over time due to friction, thereby suppressing the deterioration in print quality and the occurrence of radio interference due to noise radio waves as described above. To provide a rotating electrode for a photosensitive drum in an electrophotographic process.

[0008]

Means for Solving the Problems The present invention has been made to solve the above problems, and its gist is a rotating electrode used for a photosensitive drum of an electrophotographic process, The electrode body is basically formed in a substantially disk shape using a metal material having a spring property, and substantially curved ball-shaped contact fittings having a width in a radial direction substantially symmetrically with a rotation shaft hole interposed therebetween are each connected to one end of the circular shape. The contact portion is formed by cutting off the periphery while being connected to the plate and bending the tip portion, while forming a contact portion in contact with the inner wall of the photosensitive drum at a substantially symmetrical position around the circumference of the disk-shaped electrode body. In the use of the rotating electrode, a conductive grease is applied between the contact fitting contact portion and the fixed base contact surface of the rotating shaft. is there.

[0009]

In the present invention, in order to obtain electrical continuity between the photosensitive drum and the main body of the copying machine, substantially point contact is made by a rotating electrode formed of a metal material having a spring property instead of the conventional point contact. In addition, since conductive grease is applied near the contact portion, the effect of preventing a change in contact resistance due to wear of the contact portion can be maintained for a long time.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. First, FIGS. 1 to 3 show one embodiment of a rotating electrode for a photosensitive drum according to the present invention.
2 is a plan view, FIG. 2 is a front view, and FIG. 3 is a side view. In these figures, reference numeral 1 denotes a disk which is basically made of a substantially disk-shaped metal material and constitutes an electrode body, and it is effective to integrally mold the disk shown in the figure. In this case, it is necessary that the metal material has a spring property. For example, phosphor bronze or the like is desirable, but a material having the same spring property and electrical properties as the metal material is appropriately selected and used. It is possible.

Next, in these figures, reference numeral 2 denotes a rotary shaft hole 3
A contact metal fitting having a width in the radial direction, which is substantially symmetrical with respect to each other, has a substantially curved shape as shown in FIG. 1, and cuts the periphery while being connected to the disk 1 at one end 4. By pushing it downward, it becomes leg-like as shown in the front view of FIG. 2 or the side view of FIG. 3, and by further bending the tip of each contact fitting 2 at the position of the bending line 5,
The fold line 5 will form the contact. On the other hand, a protruding piece 6 integrally formed with the disc 1 is provided at a tip thereof with a contact portion 6a formed at a position substantially symmetrical with respect to the disc 1, that is, the rotary shaft hole 3 of the electrode body. Are arranged so as to contact the inner wall of the photosensitive drum 11.

Next, the operation of the rotary electrode of the present invention shown in the embodiment of FIGS. 1 to 3 will be described. An example of the case where the rotating electrode of the above embodiment of the present invention is used for a photosensitive drum is shown in an explanatory view of FIG. In FIG. 1, reference numeral 11 denotes a photosensitive drum, and a rotating shaft 14 erected on a fixed base 13 fixed to the photosensitive drum unit frame 12;
1 is supported by a drum cap 15 attached to one end and a bearing 16 into which the rotary shaft 14 is inserted, and is rotated in a rotation direction R by a drive source (not shown). The configuration of the rotating shaft 14 and its fixed base 13 is as shown in the front view of FIG. 5, and in the figure, reference numeral 17 denotes a contact surface with an electrode described later.

In the configuration of FIG. 4 as described above, the rotating electrode according to the present invention is the drum cap 1 of the photosensitive drum 11.
The upper surface of the disk 1 is pressed by the bearing 5 and the bearing 16, and a pair of contact fittings 2 is provided on the contact surface 17 of the rotating shaft fixed base 13 on which the rotating shaft 14 piercing through the rotating shaft hole 3 is erected. The surface contact is performed by using the vicinity of the bending line 5 as a contact portion. In this case, the contact surface 17 is fixed, while the contact fitting 2 has the disc 1
Is transmitted by the drum cap 15 and the bearing 16 to rotate in the rotation direction R, and frictional contact is made in the vicinity of the bending line 5. In the figure, reference numeral 18 denotes a conductive grease, and the conductive grease 18 is connected to the contact fitting 2. Is applied to the gap between each lower side of the bending line 5 and the contact surface 17 of the rotating shaft fixing base 13, thereby preventing a change in contact resistance due to wear of the contact portion.

In this case, the application of the conductive grease 18 in the above arrangement is particularly advantageous in that the effect of the conductive grease can be maintained for a long period of time. That is, FIG. 6 is a plan view schematically showing the flow state of the conductive grease in the rotating electrode according to the present invention. In FIG. 6, 14
Is a rotating shaft, 1 is a disk of a rotating electrode, and a folding line 5 formed at the tip of the contact fitting 2 provided symmetrically with the rotating shaft 14 interposed therebetween and a contact surface 17 parallel to the paper surface (FIG. between 4 reference), when applying a conductive grease 18 to position a from the axis of rotation 14 a distance D _1, the conductive grease 18 in the position of b from the position of a with the rotation of the rotating direction R of the disk 1 moves along the folding lines 5 (flow), the distance D ₂ next to the rotary shaft 14, which is smaller than the original distance D ₁ but rather will be conductive grease 18 as a result are drawn to the center of rotation, this The effect prevents the conductive grease 18 from flowing out, so that the effect of the grease can be maintained for a long time, and high reliability can be realized.

FIG. 4 shows a portion of the pair of protruding pieces 6 shown in FIGS. 1 to 3 and a contact portion 6a formed at the tip thereof, the portion facing the bearing 16. It is. As described above, the contact portion 6a is formed integrally with the disk 1 by a metal material having a spring property, and is pressed against the inner wall of the photoconductor drum 11 by a spring force. ,
It rotates together with the rotating electrode disk 1 to ensure electrical conduction of the photosensitive drum.

[0016]

As is clear from the above embodiments, according to the present invention, the contact portion between the rotating electrode and the fixed electrode becomes almost surface contact instead of conventional point contact, so that a change with time due to wear hardly occurs. This makes it possible to suppress the deterioration of print quality and the occurrence of radio interference due to noise radio waves, and furthermore, by applying conductive grease between the contact fitting contact portion and the fixed base contact surface of the rotating shaft, the contact fitting is provided. The grease moves in the direction of the rotation axis along the bending line of the contact portion to enable the effect to be maintained for a long period of time, and the practical effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 is a plan view of one embodiment of a rotating electrode for a photosensitive drum according to the present invention.

FIG. 2 is a front view of an embodiment of a rotating electrode for a photosensitive drum according to the present invention.

FIG. 3 is a side view of an embodiment of a rotating electrode for a photosensitive drum according to the present invention.

FIG. 4 is an explanatory diagram showing an example of a case where a photosensitive drum rotating electrode according to the present invention is used for a photosensitive drum.

FIG. 5 is a front view showing a configuration of a rotating shaft.

FIG. 6 is a plan view schematically showing a flow state of conductive grease in the rotating electrode for a photosensitive drum according to the present invention.

FIG. 7 is an explanatory diagram of a main part showing an example of a configuration of a conventional electrophotographic process.

FIG. 8 is an explanatory diagram illustrating a configuration of a photosensitive drum.

FIG. 9 is an electric circuit diagram illustrating an example of a charging circuit of the photosensitive drum.

FIG. 10 is a cross-sectional view illustrating a configuration example near a contact point of a conventional photosensitive drum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc 2, 64 Contact fitting 3 Rotation shaft hole 5 Bending line 6a, 65 Contact part 11, 31 Photoreceptor drum 14, 61 Rotation shaft 16, 63 Bearing 17 Contact surface 18 Conductive grease 32 Charger 33 Exposure device 34 Developing device Reference Signs List 35 transfer unit 36 peeler 38 fixing unit 40 paper cassette 51 OPC layer 52 pigment layer 53 metal drum 62 frictional contact 101 high-voltage power supply unit 102 corona discharge 103 scorotron charger

Claims (1)

(57) [Claims] 1. A rotating electrode used for a photosensitive drum in an electrophotographic process, wherein an electrode body is basically formed in a substantially disc shape using a metal material having a spring property and has a rotating shaft hole. A substantially curved ball-shaped contact fitting having a width in the radial direction substantially symmetrically is cut off with its one end connected to the disc, and a contact portion is formed by bending a tip end, while the disc-shaped electrode body is formed. A protrusion that forms a contact portion that contacts the inner wall of the photoreceptor drum is provided integrally at a substantially symmetrical position on the circumference of the photoreceptor drum. A rotating electrode for a photosensitive drum in an electrophotographic process, wherein conductive grease is applied between the surface and the surface.