JPS63220187A - Image forming device - Google Patents

Abstract

PURPOSE:To improve the accuracy of a gap between a photosensitive drum and a developing roller by fitting loosely a gap holding member to both end parts in the longitudinal direction of a photosensitive drum, and allowing it to abut on the developing roller. CONSTITUTION:To both end parts in the longitudinal direction of a photosensitive drum 1, gap holding members 10a, 10b of a cylindrical shape are fitted loosely so as to be freely turnable, and a developing unit 11 is energized in the direction of the photosensitive drum 1 so that the outside peripheral part of both ends of a developing roller 6 comes into contact lightly with the gap holding members 10a, 10b. Accordingly, the accuracy of the photosensitive drum 1 and the developing roller 6, which is concerned greatly in a toner developing quality can be allowed to depend on the single dimension accuracy of the gap holding members 10a, 10b. In such a way, the accuracy can be secured extremely stably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides an electrophotographic method for obtaining a desired copy from an original.
, and a photoreceptor and developing means included in an optical printer device or the like which extracts and records character image information processed by a computer, warp setter, etc. as a signal.

[Conventional technology]

Conventionally, as means for appropriately positioning the photoreceptor and the developing means, there has been a method in which, for example, a holding member of the IA image means is constructed so as to maintain a desired positional relationship while constantly abutting the photoreceptor. A developing device located close to the photoreceptor drum 101, schematically shown in 3rd yJ! ! Tri-104, which is a fine powder, is conveyed in the direction of the arrow in the figure by the image roller lθ3 in j02, and brought into contact with the photoreceptor drum 101.
Toner 104 is applied and visualized according to the rn image.

The developing roll 103 has a rotation center axis J (with l) at both ends.
A gap holding member 105 is installed, and the developing box 106 is rotatably supported by a rotation fulcrum 107.
The first gap holding member 105 is urged by the urging member 108 so as to come into contact with the photosensitive drum 101 with an M-degree pressure kettle, and the gap between the photosensitive drum 101 and the IA image roll 103 is maintained.

Problems that IJlj from C aims to solve] In the conventional technology described above, since the gap between the photoreceptor drum 101 and the developing roll 103 is greatly involved in the toner adhesion characteristics,
In order to stably obtain high quality images, it is necessary to maintain the gap with high precision.

In a developing device using one-component toner, the gap is 0. 3 to 1.0 ms is considered to be the threshold and the required degree of vI is about plus or minus 10% of the above value. In the method of bringing the gap holding member 105, which shares the rotating shaft of the developing roll 103, into contact with the photoreceptor drum 101, eccentric errors of the developing roll and the gap holding member, and gap keeping
The mounting looseness of the ttts material rotation bearing is accumulated, making the gap unstable. Therefore, in order to ensure the required accuracy, it is necessary to make the developing roll and the gap retaining member extremely precise, making them expensive to manufacture.

Furthermore, from the viewpoint of the durability of the device, some of the tree particles floating in the atmosphere away from the developing roll surface extend to the surface of the gap holding member and are compacted at the contact area with the photosensitive drum. It becomes firmly stuck to the surface. Device medicine! J'! As driving time increases,
The hard layer of the toner grows, and the precision of the gap between the photosensitive drum and the developing roll -L1 becomes a non-negligible amount. In order to solve these problems, methods have been adopted, such as having a service person clean the gap holding member 18 times, or replacing the entire developing device unit at relatively short intervals of operation time. However, the former method goes against the recent strong demand for maintenance-free technology, and the latter method makes the developing device disposable, which has no problems with durability and is expensive, so it is of no use to users. As a result, they are forced to spend money.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, the durability of the developing device such as the developing roll is 100,000 to 100,000 times the number of sheets recorded.
The lifespan of the photoconductor layer on the photoconductor drum is about 10,000 sheets, whereas the lifespan of the photoconductor layer on the photoconductor drum is currently being used for OPC (organic optical semiconductor)
In order to improve the image quality, we focused on the fact that there are about 2,000 to 2,000 square feet and are treated as consumable items that are replaced many times, and we installed a gap retaining member loosely fitted to both ends of the photoreceptor drum in the longitudinal direction. It was configured so as to come into contact with the roll.

(Function) The gap retaining members loosely fitted to both ends of the photoconductor drum are operated while being sandwiched between the photoconductor drum surface and the developing roll surface.The gap maintaining members are loosely fitted so as to be rotatable. Therefore, it rotates at the same circumferential speed as the developing roll and slides on the surface of the photoreceptor drum.(distance between photoreceptor drum and II!IFI holding member) = (thickness of gap holding member), so the above distance 'I
In order to ensure r1FX, it is only necessary to guarantee the accuracy of the thickness of the gap retaining member (this eliminates the accumulation of errors in multiple parts. Therefore, it is possible to easily achieve even extremely strict accuracy requirements. be.

[Embodiment] An embodiment according to the present invention is shown in FIG. 1. Seven flanges 2at2b each having a rotating shaft are fixedly installed at both ends of a photoreceptor drum 1, and bearings 3as3b supporting the rotating shaft are respectively attached to a drum housing 4. is held fixed. One flank 2b
The rotating shaft protrudes outside the drum housing 4, and a gear 5 for power transmission is installed on the protrusion. The gear 5 meshes with a drive gear (not shown) on the apparatus main body side, and rotates the photosensitive drum 1 at a predetermined speed. Placed close to photoreceptor drum 1] 3! The image knoll 6 is supported at both ends by a bearing 8 held in the developer housing and the 1A imager housing, one end of which protrudes outside the housing, and a gear 8 for drive transmission is installed. The gear 9 meshes with a drive gear (not shown) on the main body of the apparatus and rotates the developing roll 6 at a predetermined speed.The tri°-fine powder (not shown) in the housing 7, which is not shown as the IJL image roll 6 rotates, develops j+. , - placed on the outer surface of the photoreceptor drum!
will be transported towards.

Cylindrical gap retaining members toa and tab are rotatably fitted into both ends of the photosensitive drum 1 in the longitudinal direction. The outer peripheral portions of the developing roll G at both ends thereof are gap retaining members 10a.
, lOb, the developing unit is urged toward the photoreceptor drum so as to lightly touch 1.

FIG. 2 shows an enlarged view showing the functions of the II Fi holding members 10a and 1Ob. The gap holding member 10a is the photosensitive drum 1
It can be installed by setting a suitable clearance between the This clearance (C in the figure) is shifted to one side of the loose fitting part on the front surface where the developing roll 0 contacts the gap holding member 10a, and in this area, the photoreceptor drum 1, the developing roll 6, and the gap holding member 10a The gap Fi (G in the figure) required for good toner image formation is equal to the thickness of the gap retaining member (T in the figure). Even when the photosensitive drum and the developing roll rotate relative to each other, the soft bacteria is retained, and G is always equal to T.

Therefore, it is only necessary to keep the value of G highly accurate (for this purpose, it is sufficient to keep T uniform).

The gap retaining member is made of a resin that has a low coefficient of friction, for example,
Boriacenol, polyethylene, nylon, amide-imide engineering plastics, or gold
F! J Temporary surface coated with lubricating material,
It is extremely cheap to manufacture. In addition, the engineering plastic material can be used for injection molding and gold rt.
According to F4FW provisional, the dimensional accuracy of the wall thickness is, for example, the wall thickness (
It is easy to secure a value of plus or minus 30μ for T)=0.31■, and the value of G can be secured extremely stably.

〔Effect of the invention〕

According to the present invention, it is possible to make the accuracy of the gap 11 (G) between the photoreceptor drum and the developing roll, which greatly affects the quality of toner development, depend on the dimensional accuracy of a single gap holding member,
G accuracy can be ensured in an extremely stable manner.

Another effect of the present invention is that since the gap holding member is packed in the photoreceptor drum, the photoreceptor has a relatively short printing life (2,000 to 20,000 sheets) and is a regularly replaced part. Since the drum can be replaced with a new part at the same time, the durability problem is solved. That is, the thickness of the gap holding member gradually changes due to the adhesion of fine toner particles floating in the atmosphere away from the developing roll surface.
This problem will be solved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the device showing how the gap retaining member of the present invention is installed. Figure m2 is an enlarged view for explaining the function of the gap retaining member of the present invention. FIG. 3 is a schematic diagram showing a conventional gap maintaining method. ``2nd m person -+r Iko Epson Co., Ltd. 1st! ! 1 Figure 2 104 Tonano 084 size V Kichip Saio Figure 3

Claims (1)

[Claims] A photoreceptor having a conductive base and a photoconductive layer provided on the base, a developing means for visualizing at least an electrostatic latent image formed on the photoreceptor, and free space at both longitudinal ends of the photoreceptor. An image forming apparatus comprising: a gap holding member that fits into the developing means and is provided so as to come into contact with the developing means.