JPH03167569A - Electrifying mechanism for image forming device - Google Patents

Abstract

PURPOSE:To eliminate such trouble that sticking of dust makes the surface potential of a photosensitive body irregular which results in adverse effect to image formation by laterally reciprocating a planner grid with respect to the direction in which a photosensitive body surface moves. CONSTITUTION:The planar grid 52 is arranged between the photosensitive body 16 and the corona charger 42, and is energized by an extension spring 50. When an elliptic roller 58 rotates, a wire 54 stretches or loosens, and the planar grid 52 laterally reciprocates with respect to the surface of the photosensitive body 16 while being energized by the extension spring 50. Since the adverse effect of the stain of the plate grid 52 is distributed, the part where a surface potential is very high is not created on the surface of the photosensitive body 16. And hindrance in image formation is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a charging mechanism used in an N-Kaikatakai device, etc., and more particularly to a charging mechanism in which the grid portion of the Scorotron method is improved. (Prior Art) In a copying process using a photoconductor or the like in the field of electrophotography, the surface of a photoreceptor is normally charged, information is exposed to the charged portion, and the latent image formed by the exposure is transferred to a developer, etc. This is converted into a visible image, which is then transferred onto transfer paper to make a copy.

In such a process, a charging device is used to form an image on the photoreceptor surface and remove static electricity.Charging devices are broadly classified into scorotron and corotron type. A scorotron charging mechanism usually consists of a flat grid facing the surface of the photoreceptor and a linear corona charger. A voltage is applied to the corona charger to generate corona discharge, which charges the surface of the photoreceptor through a grid to provide a predetermined surface potential.

The grid of a conventional charging mechanism is fixedly arranged at a predetermined distance from the photoreceptor surface and along a direction transverse to the moving direction of the photoreceptor surface. (Issues that the invention aims to solve!) However, if the grid is fixed, dust etc. will adhere to the grid due to long-term operation. The adhesion of such dust causes unevenness in the surface potential of the photoreceptor surface, which has an adverse effect on image formation. In recent years, there has been an increasing demand for devices to be more compact, and it is desirable to place the grid as close to the photoreceptor surface as possible. but,
If the grid is placed too close to the photoconductor surface, there is a problem in that the grid's eyes appear on the surface potential of the photoconductor. Therefore, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a charging mechanism for an image forming apparatus in which dust and the like adhering to the grid do not adversely affect the surface potential of the photoreceptor surface.

Another object of the present invention is to provide a charging mechanism for an image forming apparatus that can bring a grid sufficiently close to the surface of a photoreceptor.

(Means for Solving the Ill Problem) As a result of extensive research, the present invention has found that during discharge, if the grid is moved on the surface of the photoreceptor without being fixed, dust will not unexpectedly adhere to it, and that the grid with dust attached to it will not be exposed to the photoreceptor. By moving the body back and forth by a certain distance in the transverse direction of movement, uneven surface potential on the photoconductor surface can be eliminated surprisingly easily, and even when placed close to the photoconductor surface, the grid's eyes remain sensitive to light. The knowledge that it does not affect the appearance of the body led to the invention of the following configuration.

That is, according to the present invention, the photoreceptor is disposed opposite to the surface of the photoreceptor,
A charging mechanism for a scorotron-type image forming apparatus comprising a corona charger and a grid, wherein the grid is provided so as to be movable back and forth in a direction transverse to the direction of movement of a photoreceptor surface. A mechanism is provided.

The present invention also provides a storage distance of 1 m between the grid and the photoreceptor surface.
It can be characterized in that it is in the range of m to 5 mm. Further, the present invention is characterized in that the distance during the grid reciprocating movement is 1 mm or more. Further, in the present invention, the photoreceptor is of a drum type, and a transmission means for converting the rotational force of the photoreceptor into reciprocating power of the grid can be disposed between the photoreceptor and the grid. (Example) Preferred embodiments of the charging mechanism of the image forming apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a copying machine equipped with a charging mechanism according to the present invention. 1st
As shown in the figure, on the top of the main body of the copying machine 10 is a document placement section 1.
2 is formed, and an optical system exposure section 14 is arranged on the upper part of the main body. A photoconductor 16 is rotatably arranged below the optical system exposure section 14, and a charging mechanism section 1 is arranged around the photoconductor 16.
8. A developing mechanism section 20, a transfer mechanism section 22, and a cleaning section 24 are provided. The surface of the photoreceptor 16 is kept at a constant ffi? by the charging mechanism section 18. ! When the charging section is positioned below the exposure section 14, the document information is exposed. The charged part that has been turned into a latent image by exposure is the developing mechanism 1! FI
When facing the developing sleeve 21 of I20, toner is supplied from the developing sleeve 21, thereby forming a visible latent image on the surface of the photoreceptor 16. On the other hand, paper feed cassettes 26 and 2 are provided on the side of the copying machine main body 10.
6 is attached, and the transfer paper is transferred to the nip rollers 28, 28, 28.
, and the photoreceptor l6 and the transfer mechanism section 22 via the conveyance path 30.
It is supplied between A toner image, which is a visible image on the surface of the photoreceptor 16 described above, is transferred onto the fed transfer paper. The transfer paper is conveyed to the fixing mechanism section 33 via the conveyance belt 32, and the toner is fixed onto the transfer paper by heat or the like. As a result, an image is formed on the surface of the transfer paper, and the image is sent out of the main body 10 via the nim roller 34, completing the copying. Note that the surface of the photoreceptor 16 after copying is cleared by the cleaning section 24 and the static eliminator, and is again charged to a certain level by the charging device.

As shown in FIG. 2, the charging mechanism section 18 includes a pair of machine frames 39,
39, and are also arranged substantially transversely to the rotational movement direction of the photoreceptor 16, and at regular intervals according to the corona discharge capacity. The charging mechanism section 18 consists of a shield case 40 and a corona charger 42. The shield case 40 surrounds the corona charger 42 from three sides, and one side is opened so that the corona charger 42 faces the six sides of the photoreceptor. I have to. Further, the photoreceptor 16 is arranged substantially below the charging mechanism section and is rotatably attached between the machine frames 39 through a rotary shaft 44. A crank-shaped mounting bracket 4 is attached to the left machine frame 39 shown in FIG.
8 is provided, and a tension spring 50 is attached to the mounting bracket 48. A flat grid 52 is attached to the other end of the tension spring 50 as shown in FIG. A tensioning wire 54 is attached to the right end of the flat grid 52, and the wire 54 is wound around a tensioning bin 56 approximately half a circumference. The wire 54 is further wound approximately ⅓ around an oval roller 58, and then its end is fixed to a support pin 60. The tension bin 56 and the support bin 60 are protruded from the shield case 40, the oval roller 58 is attached to a rotatable rotating pin 62, and the rotating pin 62 is also attached to the shield case 40. Therefore, the flat grid 52
6 and the corona charger 42, and is biased in the direction of arrow A in FIG. 3 by a tension spring 50. Further, when the oval roller 58 rotates, the wire 54 is tensed or relaxed, so the flat grid 52 is moved by the tension spring 5.
The grid 52 reciprocates in the transverse direction of the surface of the photoreceptor 6 while receiving a bias of 0, and as a result of this reciprocating movement, the grid 52 is shifted by a width of 1 mm or more.

Further, support members 66 are protruded at predetermined positions of the shield case 40, and the tips of the support members 66 are brought into contact with the flat grid 52. The length of this support member 66 is adjustable, and the distance between the surface of the flat grid 52 and the surface of the photoreceptor 16 can be adjusted within the range of 1 mm to 5 mm. The flat grid 52 has a mesh having a plurality of slits, and serves as a varistor electrode. The flat grid 52 is electrically connected to the varistor 68 via the tension spring 50 and the mounting bracket 48, and the varistor 68 is grounded. Further, a bevel gear 70 is attached to the rotating pin 62 to which the oval roller 58 is attached. The bevel gear 70 includes
The rotational force of the photoreceptor 16 is transmitted through the bevel gear 72, the gear 74, and the gear 78 attached to the photoreceptor 16. According to the charging mechanism configured as described above, when the photoreceptor 16 is driven, a voltage is applied to the corona charger 42 of the charging mechanism 18 to cause corona discharge. As a result, the surface of the photoreceptor 16 is charged with a predetermined charge through the flat grid 52, and a surface potential is applied. If such a charging operation is repeated for a long time, dust may adhere to the flat grid 52. When dust adheres to the flat grid 52, the adhered portion tends to increase the surface potential of the opposing photoreceptor 16 surface. However, in the present invention, as the photoreceptor 16 operates, the elliptical roller 58 rotates via the transmission means, and the wire 54 is tensioned or relaxed. For this reason, the flat grid 5
2 moves back and forth along the transverse direction of the photoreceptor 16 surface. Therefore, the influence of contamination on the flat grid 52 is dispersed, and no part of particularly high surface potential is generated on the surface of the photoreceptor 16, so that there is no problem in copying the image. In such a reciprocating movement, the reciprocating width is important, and the degree of dirt on the flat grid 52 and the distance between the grid and the photoreceptor surface are issues, but at least the reciprocating width should be at least 1 mm. It is desirable to do so. Furthermore, by reciprocating the flat grid 52, even if the flat grid 52 approaches the photoreceptor 16 surface, the influence of the slits will not affect the photoreceptor 16 surface much. The distance between the flat grid 52 and the surface of the photoreceptor 16 is 1 mm to 5 mm.
In particular, a range of 1 mm to 3 mm is desirable, and in such a range, the reciprocating movement will not be affected by the slit.

Incidentally, the charging device of the above embodiment can be provided in the transfer mechanism section or the static eliminating section.

(Effects of the Invention) As explained above, according to the present invention, in the scorotron method, when the flat grid is moved back and forth along the direction transverse to the direction of movement of the photoreceptor surface, dust is less likely to adhere to the flat grid. Also, it eliminates the bias in the surface potential of the photoreceptor surface due to dust attached to the flat grid. Therefore, the charging mechanism is not adversely affected by cliff dust! The i-forming device provides good development. Furthermore, even if the flat grid is brought close to the photoreceptor surface, the grid's mesh does not affect the surface potential of the photoreceptor surface, and the adjustment function on the photoreceptor surface is not lost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a copying machine equipped with a charging mechanism according to the present invention, FIG. 2 is a side view of a mounting portion of the charging mechanism, and FIG. 3 is a plan view of a flat grid. 10: Copy machine 16:
Photoreceptor 18: Charging mechanism 40: Shield case 42: Corona charger 52: Flat grid. Dehajin Mita Kogyo Co., Ltd. Figure 2 Figure 3

Claims (3)

[Claims] (1) In the charging mechanism of a scorotron-type image forming apparatus, which is arranged to face the photoreceptor surface and consists of a corona charger and a grid, the grid can be moved back and forth in a direction transverse to the direction of movement of the photoreceptor surface. A charging mechanism for an image forming apparatus, characterized in that it is provided in a charging mechanism. (2) The distance between the grid and the photoreceptor surface is 1 mm to 5 mm.
2. The charging mechanism according to claim 1, wherein the charging mechanism is in the range of mm. (3) The photoreceptor is a rotating drum photoreceptor, a transmission means is provided between the drum photoreceptor and the grid, and rotation of the drum photoreceptor is converted to reciprocating movement of the grid via the transmission means. The charging mechanism according to claim 1 or 2, characterized in that: