JPH01232367A - Power feed mechanism for image forming device - Google Patents

Abstract

PURPOSE:To stably maintain printing quality over a long period of time by fixing respective electrode elements to a frame of the device and forming a pressing part so as to press the terminal of a precharger so that the precharger comes into contact with a photosensitive body to maintain the specified distance between a wire and the photosensitive body. CONSTITUTION:The electrode element 27 for power feed is formed by connecting the pressing part 29 which elastically presses the terminal 10 and a power feed part 30 by a conductor 31 and covering the same by an insulating material 32. The power feed part 30 is fitted into a hole 34 of a projecting part 33 provided to a case and is fixed by a screw 35. The electrode element 28 for grounding is formed by connecting the pressing part 36 which elastically presses the terminal 11 and a grounding part 37 by a conductor 38. The precharger 2 is, therefore, pressed via a roller 9 to the photosensitive body by the pressing forces of the electrode elements 27, 28 on the terminals 10, 11. The specified distance between the corona wire and the photosensitive body is thereby maintained, by which the surface potential is stabilized and the printing quality is stably maintained over a long period of time.

Description

[Detailed Description of the Invention] [Summary] Regarding a power supply mechanism for supplying power to a front charger of an electrophotographic image forming apparatus, the present invention relates to a power supply mechanism for supplying power to a front charger of an electrophotographic image forming apparatus, and a distance-travel between a corona wire of the front charger and a photoreceptor. The purpose of this printer is to easily maintain high print quality over a long period of time by easily converting the image. In an image forming apparatus having a front charger having a terminal and a grounding terminal on the upper surface, a pressing part that elastically presses the power supply terminal and a power supply part connected to a power source are integrally connected by a conductor. and a grounding electrode formed by integrally connecting a pressing part that elastically presses the grounding terminal and a grounding part to be grounded by a conductor, and each of these electrodes. The children are each fixed to a fixed part of the device.

[Industrial application field]

The present invention relates to a power supply mechanism for supplying power to a pre-charger of an electrophotographic image forming apparatus.

Recently, a laser printer using a laser as an exposure means (
Image forming devices) have become widely used, but
In this case, there is a strong demand from users to maintain stable high print quality over a long period of time. In order to satisfy this demand, it is effective to stabilize the potential placed on the drum-shaped photoreceptor by the pre-charger.

[Conventional technology]

For this reason, attempts have been made in the past to have each insulator block provided at both ends of the pre-charger support a pair of rollers, and to bring these rollers into contact with a portion of the photoreceptor outside the printing area. ing. Due to this roller contact, the distance between the corona wire stretched between each block and the photoreceptor can be kept constant, and the potential of the photoreceptor can be stabilized.

[Problem to be solved by the invention]

In the case of this type of roller, in order to ensure that the roller comes into contact with the photoreceptor, a biasing means for biasing the pre-charger toward the photoreceptor is required. Further, a power supply mechanism is required to supply power to the pre-charger, but conventionally, an energizing means has been provided separately from the power supply mechanism, resulting in a complicated structure.

The present invention provides power supply to an image forming apparatus that can easily maintain the long-term stable maintenance of high print quality by easily performing power supply to the pre-charger and the distance between the corona wire of the pre-charger and the photoreceptor. The purpose is to provide a mechanism.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention includes a front charger that is provided with a positioning roller on the lower part that contacts the surface of the photoreceptor outside the image forming area, and that is provided with a power supply terminal and a grounding terminal on the upper surface. In the image forming apparatus, the power feeding electrode element is formed by integrally connecting a pressing part that elastically presses the power feeding terminal and a power feeding part connected to a power source with a conductor, and a power feeding electrode that elastically presses the grounding terminal. A grounding electrode element is provided, which is formed by integrally connecting a pressing part that presses the object and a grounding part that is grounded by a conductor, and each of these electrode elements is fixed to a fixed part of the device.

[Function] Each electrode element is fixed to a fixed part such as the frame of the device, and each pressing part presses each terminal provided on the top surface of the front charger. The roller is energized to ensure that the roller comes into contact with the photoreceptor. Therefore, the distance between the wire and the photoreceptor is always kept constant, the potential on the surface of the photoreceptor is stabilized, and stable print quality can be maintained over a long period of time.

Moreover, power supply and grounding can be performed using these electrodes, and the structure becomes simple.

〔Example〕

The invention will now be described in detail in conjunction with the drawings.

FIG. 3 is a side view showing an outline of the main parts of the image forming apparatus according to the present invention, in which l is a drum-shaped photoreceptor, 2 is a front charger,
3 is a cleaner, which is assembled into a common unit 4 (the shaded portion corresponds to the side plate 4a). 5 is a rigid blocking plate.

The pre-charger 2 has a structure shown in detail in FIG. 4, and 6 is a molded case. Blocks 7.8 are integrally connected to both ends of the molded case 6. The block 7 includes a pair of rollers 9 facing perpendicularly to the paper surface of FIG.
A terminal 10 for power supply is provided, and the block 8 is provided with a pair of rollers 9 and a terminal 11 for grounding. One part of the corona wire 12 is fixed to the terminal 10, and the other end is fixed to the spring 13. It is locked to the locking part 14 of the block 8 via. The corona wire 12 is positioned by a positioning portion 15 of the block 7 and a positioning portion 16 of the block 8, and is applied with tension by a spring 13.

Further, 17 is a mesh grid, and the mesh grid 17 is positioned at the positioning portion 18.19 of each block 7.8 and attached to the lower part of the front charger 2.

Reference numeral 20 denotes a protrusion provided on the inner wall of the molded case 6, and a square hole 21 provided in the chassis side plate that is provided oppositely and connected to the mesh grid 17 in a U-shape is engaged with the protrusion 20. . The position of each positioning part 15°16,18,19 is set based on the center of the roller 9 supported at the bottom of each block 7.8, so the corona wire 12
The distance between the mesh grid 17 and the mesh grid 17 is always kept constant.

As shown in FIG. 3, when the photoreceptor 1 rotates with the roller 9 in contact with a portion of the photoreceptor 1 outside the image forming area and the pre-charger 2 attached, the corona wire 12 and The mesh grid 17 follows the surface of the photoreceptor 1 via the rollers 9. Although not shown in the drawings, an exposure device, a developing device, a transfer device, and a static eliminator, which together with the pre-charger 2 constitute an image forming means, are arranged around the photoreceptor 1. It is close to the container 2 on the opposite side from the cleaner 3.

The cleaner 3 includes a fur brush 22 and a fur brush 2.
blades 23 and 24 that scrape off toner adhering to photoreceptor 1; and scraper 25 that scrapes off residual toner on photoreceptor 1.
and a screw 26 for discharging toner removed by the blades 23, 24 and the scraper 25 to the outside.

The blocking plate 5 has approximately the same length as the photoreceptor 1,
It is removably attached to each side plate 4a of the case 4 so as to be close to the photoreceptor 1 over almost the entire length thereof. This blocking plate 5 is
This is to prevent toner flying up from the developing device from staining the corona wire and the surface of the photoreceptor, and because it is a rigid body, it can maintain its blocking effect for a long period of time. This shielding plate 5 is removed when cleaning the front charger 2 or the like.

Power supply and grounding to the pre-charger 2 configured as described above are performed as follows.

In FIG. 1 showing the power feeding mechanism of the image forming apparatus, 27 is a power feeding electrode, and 28 is a grounding electrode.

As shown in detail in FIG. 2, the electrode element 27 integrally connects a pressing part 29 for elastically pressing the terminal 10 and a power feeding part 30 connected to a power source through a conductor 31. The pressing portion 29 and the portions of the power feeding portion 30 other than the end surface 30a are covered with an insulating material 32. This electrode element 27 is configured by fitting the vicinity of the power supply part 30 into the hole 34 of the protrusion (fixing part) 33 provided on the side plate 4a of the case 4, and feeding the power supply screw 35 inserted into the protrusion 33. It is screwed into the screw hole 30b of the section 30 and fixed to the side plate 4a. In this state, the pressing portion 29 is pressed into contact with the terminal 10 of the front charger 2. The power supply connection to the electrode element 27 is performed by fitting a plug (not shown) on the power supply side into the tip 33a of the protrusion 33; , and power can be supplied.

In addition, in the case of a type in which a pre-charger etc. are not incorporated into the unit as in this example, the electrode element 27 may be attached to the frame (fixed part) of the apparatus.

The electrode element 28 is configured by integrally connecting a pressing part 36 for elastically pressing the terminal 11 and a grounding part 37 to be grounded by a conductor 38.

The grounding portion 37 is attached to a metal plate (fixed portion) (not shown) attached to the outside of the side plate of the case 4, and is grounded via the metal plate and the varistor. In this state, the pressing part 3
6 is pressed into contact with the terminal 11.

Power is supplied using the electrodes 27 and 28 provided in this way,
Although grounding can be ensured, these electrodes 27
．． The pre-charger 2 is urged toward the photoreceptor 1 by the pressing force of the terminal 10.11 of the roller 9, and the roller 9 reliably contacts the photoreceptor 1. Therefore, the distance between the photoreceptor 1 and the corona wire 12 can always be kept constant, the surface potential of the photoreceptor 1 can be stabilized, and printing quality can be stably maintained over a long period of time.

This effect becomes more noticeable when the shielding plate 5 is provided and the distance between the mesh grid 17 and the corona wire 12 is kept constant as in this example.

FIG. 5 shows the structure of a printer (image forming apparatus) to which the present invention is applied. In the figure, 101 is a casing, 102 is a case foot attached to the lower part of the casing, and the illustrated components are housed in the casing 101. The operation of this printer is as follows.

During printing, the photoreceptor 1 is rotated counterclockwise as shown by the arrow, and the bin roller 103 is rotated once at a predetermined timing with this rotation. The surface of the rotating photoreceptor 1 is first uniformly charged by the pre-charger 2, and then a latent image is formed thereon by an exposure means 113 using a laser.

This latent image is developed by a developing device 106 to become a toner image. On the other hand, the topmost sheet of paper stacked in the cassette 102 is fed out by a rotating pick roller 103, conveyed by feed rollers 104 and 105, and sent to the transfer position (A), where it is transferred. The toner image is transferred onto the paper by the device 107. Thereafter, the paper is sent to a fixing position (b), where the toner image is fixed by a fixing device 108. The paper that has been fixed is transferred to the feed roller 10.
9 and 110, and is discharged to the stack section 112 by a discharge roller 111.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to achieve the following various excellent effects.

(J) Since the pre-charger is biased toward the photoreceptor by two electrodes and the roller is brought into contact with the photoreceptor, the distance between the corona wire and the photoreceptor can always be kept constant. . Therefore, it becomes possible to stabilize the photoreceptor surface potential and stably maintain high print quality over a long period of time. Further, since the above-mentioned biasing is performed elastically, high component precision is not required.

(2) Since these electrodes are designed to serve both as power supply and grounding, the structure is simplified.

(3) By stabilizing the power supply, charging failures and leakage discharge can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a power supply mechanism of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a plan view showing the structure of a power supply electrode according to an embodiment of the present invention, and FIG. 3 is an implementation of the present invention. FIG. 4 is a front view showing the structure of a pre-charger according to an embodiment of the present invention; FIG. 5 is a schematic explanatory diagram of the structure of a printer to which the present invention is applied. In the figure, 1 is a photoreceptor, 2 is a front charger, 9 is a roller, 10 is a power supply terminal, 1] is a grounding terminal, 12 is a corona wire, 27 is a power supply electrode, 28 is a grounding electrode , 29.36 is a pressing part, 30 is a power supply part, 31.38 is a conductor, 33 is a protruding part (fixed part), and 37 is a grounding part.

Claims (1)

[Claims] A front charger comprising a positioning margin (9) at the bottom that contacts the surface of the photoreceptor outside the image forming area, and a power supply terminal (10) and a grounding terminal (11) at the top. (2) The image forming apparatus includes a pressing portion (2) that elastically presses the power supply terminal (10).
9) and the power supply part (30) connected to the power supply by connecting the conductor (31
) and a pressing portion (
36) and a grounding part (37) to be grounded are integrally connected by a conductor (38), and each of these electrodes (28), (28) is connected to the device. A power supply mechanism for an image forming apparatus, characterized in that the power supply mechanism is fixed to a fixed portion of the image forming apparatus.