JPS61240272A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent blade rolling-up, cleaning failures, filming, etc., and to form an image of good quality by making the hardness of a cleaning member different partially, and making an abutting pressure of direction of an abutting surface on an image carrier body different in position. CONSTITUTION:The hardness of non-developed image corresponding area (a), (a) parts 66', 66' of a plate-shaped cleaning blade 66 which is held by an inserting and holding part between bent suspending parts of two pieces of plate- shaped blade holders 67 (67A, 67B) is made lower successively toward both sides from a boundary part of a developed image corresponding area (b). A toner is formed already by a copy cycle until the previous time in a developed image area (x) in a photosensitive drum 20, it serves as a lubricant, and the frictional resistance of an abutting surface of the cleaning blade 66 is low. Also, the hardness of the non-developed image corresponding areas (a), (a) of the cleaning blade 66 is lower than that of the area (b), therefore, the contact pressure is low, and the frictional resistance of the abutting surface to the photosensitive drum also becomes low. In this way, rolling-up of the blade 66, cleaning failures, drum filming, etc. can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus equipped with a cleaning device.

[Technical background of the invention and its problems] Generally, in an image forming apparatus such as an electronic copying machine, a cleaning blade (cleaning member) is used to remove untransferred toner (developer) remaining on a photoreceptor drum serving as an image bearing member. It is designed to be scraped off.

By the way, if a large frictional force exists between the photoreceptor drum and the cleaning blade, the photoreceptor drum surface may be damaged, toner may be filmed on the drum, and the blade may not be able to maintain its original contact form due to stress. As a result of investigation, it has been found that due to curling and the electrostatic influence caused by friction, for example, a uniform surface potential cannot be obtained during the charging process, resulting in image unevenness and fogging. Also, in order to reduce the vibration force, it is possible to reduce the cleaning blade pressure.
In this case, cleaning, which is the original function, cannot be performed, resulting in poor cleaning or filming.

Therefore, in the past, attempts have been made to add a lubricant such as wax to the developer as a measure to reduce the frictional force between the blade and the photoreceptor. However, in this case, there are disadvantages in that the lubricant such as wax in the toner deteriorates the toner's fixing properties and causes so-called filming, which is the formation of a thin toner film on the photoreceptor. This makes the image quality highly unstable and prevents its practical use.

In addition, it has been known to apply a lubricant such as wax to the surface of the photoreceptor, but the film thickness of the lubricant on the photoreceptor must be set to a level that does not impede the RA electric current characteristics of the photoreceptor, that is, several There was no way to maintain the thickness below about 100 angstroms over a period of time. Also, the blades are low ffl
Attempts have been made to improve the friction coefficient of the material, but the problem still remains that additives cause a decline in other properties, especially mechanical strength. In addition, in conventional copying machines using the blade cleaning method, the hardness of the photoreceptor is much smaller than that of Fe, Al, etc. (e.g. SC photoreceptor, Vickers hardness of around 50 kg/mi2), When a blade or the like comes into contact with the photoreceptor, the photoreceptor often deforms due to pressure over time, which significantly reduces image quality and reliability.

For this reason, conventional means have been practically used to release the contact between the blade and the drum when the drum is stationary.

However, the method in which the blades are brought into contact and released has a drawback in that the blades themselves become stained with toner, resulting in poor images.

Further, when the cleaning blade is located above the photoreceptor, there is a drawback that when the blade is released, the toner that cannot be cleaned often stains the inside of the machine. Furthermore, as a result of imparting such movement to the blade, there is a problem in that the accuracy of contact with the photoreceptor is likely to be disturbed.

Furthermore, during the initial installation of a photoreceptor drum, there are cases in which an operator or service person generally scatters a lubricating powder such as polyvinylidene fluoride of about δμI on the drum to reduce the friction between the drum and the blade. ,
The work is done manually, which is cumbersome, and there are problems with reliability as the drum is touched during the work.

Other attempts have been made to form a single layer of toner on the photoreceptor during initial setting. As shown in FIG. 6, first the drum is rotated, and at the same time the developing bias is reversed to form a single layer of toner on the photoreceptor during period A, and then during period B during the second rotation of the drum. By bringing the blade into contact with the blade, the toner layer is used as a lubricant. However, in the contact area between the photoreceptor and the blade, where a single layer of toner is not formed, there is still a problem of rIl friction resistance, which causes the blade to turn over and damage the photoreceptor.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its object is to provide an image cleaning device that has a relatively simple configuration and is capable of solving the above-mentioned problems. An object of the present invention is to provide a forming device.

[Summary of the Invention] In order to achieve the above object, the present invention provides an image forming apparatus including a cleaning device that performs cleaning by bringing the tip of the cleaning member into contact with an image bearing member. This is characterized in that the contact pressure in the direction of the contact surface to the image carrier is varied depending on the position.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show the external appearance of an electronic copying machine to which the image forming apparatus of the present invention is applied. In the figures, 1 is a copying machine body with a built-in copying mechanism, and 2 is attached to the right side of the copying machine body 1. The paper feed cassette 3 is a paper discharge tray attached to the left side of the copying iron main body 1. A document table 4 is provided on the top surface of the copying machine main body 1 and is capable of reciprocating in the left-right direction (in the direction of arrow a - force). 6..., exposure setting key 7a
, 7b, and an operation panel 10 on which input keys such as a print key 8 and the like are arranged.

The document table 4 includes a document placement plate (glass plate) 12 on which a document 11 is placed, and a document cover 13 that covers the top surface of the document placement plate (glass plate) 12 .

Further, the cassette cover 14 of the paper feed cassette 2 has a third
As shown in the figure, there is provided a manual paper feed tray 15 for manually feeding paper P' as appropriate. In addition, 16 shown in Figure 3
I! 1III switch.

Next, the internal mechanism of the electronic copying machine will be explained with reference to FIG. In the figure, reference numeral 20 denotes a drum-shaped photoreceptor (photoreceptor drum) disposed approximately in the center of the copying machine main body 1, and the photoreceptor drum 20 is opened to the document table 4 in the direction of the arrow by a drive mechanism (not shown). It is driven by First, a document image uniformly charged by a charger 21 and uniformly irradiated by an exposure lamp 22 is transferred to a focusing light transmitter (product name: Self-Oak Lens Array).
23 to form an electrostatic latent image on the photosensitive drum 20.

The formed electrostatic latent image is turned into a toner image and sent to the transfer charger 25 side by a developing device 24 including a developing roller 24A.

The automatically or manually fed paper P or P- is fed by the paper feeder W126,
The toner image formed thereon is transferred onto MP or P' by a transfer charger 25. Furthermore, the toner image is peeled off from the photoreceptor drum 20 by a peeling charger 27 using AC corona discharge, passes through a conveyance path 28, is fused and fixed onto a paper P (Pl) by a fixing device 29, and is transferred to a tray 3 that can freely move WIF12 by an ejection roller 30. On the other hand, the contact photo drum 2 that has transferred the toner image onto the paper P (P')
The residual toner remaining on the surface of the cleaning device H (cleaning device f
t>31, and the photosensitive drum 2 is cleaned by the bypass slit light 32 which branches the light from the exposure lamp 22.
The potential above 0 is partially lowered to below the level to make the next copy operation possible.

A fan 33 serves as a cooling device, and exhausts heat generated from the heat-generating exposure lamp 22 and the fixing device 29 inside the machine.

Inside the copying machine main body 1, an upper frame and a lower frame (not shown) are pivotally supported at one end via a support shaft 37, and the other ends of both frames are configured to be opened at a desired angle, for example, 25 degrees. ing. The upper frame is provided with a charger 21, a focusing light transmitter 23, an exposure lamp 22, a developing device 24, etc. around the photoreceptor drum 2o. Each device such as a cleaning device M31 and a static elimination lamp 32 is attached by appropriate means, and a cooling device 133, a paper feed roller 38 of a paper feed device 26, and a document table 4 are also attached to the frame. It constitutes an upper unit 1A. Further, various mechanisms such as a paper feed cassette 2, a transfer charger 25, a peeling charger 27, a conveying path 28, a forming guide plate 39, a fixing device 29, a pair of ejection rollers 30, a tray 3, etc. are attached by appropriate means to form the lower unit 1B. It consists of After rotating and removing the front cover 1a of the copying machine main body 1, the structure is such that it can be opened and closed almost along the transport path 28 of the paper P (PM) via a housing opening/closing device (not shown). Even when paper P (P') becomes jammed on the conveyance path 28, it can be easily taken out.

In addition, 50.50 in FIG. 3 corrects the inclination of the leading edge of automatically fed paper P or manually fed paper P- in the paper feed cassette 2, and forms a toner image on the photoreceptor drum 20. Paper P or P according to the timing of the movement.
- is a pair of registration rollers that supplies the transfer charger 25, and 51 is a paper detection switch disposed immediately before the pair of registration rollers 50.50.

52 is a paper feed switch, 53 is a total counter, 54 is a paper empty switch that detects when the paper P in the paper feed cassette 2 is empty, and 55 is a developing device 24.
56 is a toner cartridge, 58 is a toner concentration detector, and 59 is an imager upper cover, which prevents the document table 4 from moving unless these are closed. Further, through this opening, the toner cartridge 56 can be replaced and the developing device 24 can be replaced and removed.

Further, 60 is a high voltage transformer, and a shield case for the transfer charger 25 and the peeling charger 27 is formed integrally with the casing of the high voltage transformer. Reference numeral 61 designates a static elimination brush 62 as a handle formed for opening and closing the upper unit 1A, 63 a reflector surrounding the back of the exposure lamp 22, and 64 an auxiliary reflector.

Further, 65 is a weight for bringing a cleaning blade 66, which is a cleaning member of the cleaning device, into contact with the photoreceptor drum 20 at a constant pressure, and a solenoid (not shown) causes the blade to move toward and away from the photosensitive drum 20.

Note that 67 is a blade holder (holding means) that holds the cleaning blade.

Note that the reflector 63, the auxiliary reflector 64, and the convergent light transmission body 23 are assembled as one unit.

Next, the relationship between the cleaning device 31, the photosensitive drum 20, the developing roller 24A, and their surroundings will be explained with reference to FIGS. 4 and 5.

In FIG. 4, a cleaning device 31 is arranged on the left side of the photosensitive drum, a developing roller 24A is arranged on the right side of the photosensitive drum, and an exposure lamp 22. An optical system including a convergent light transmission body 23 and the like is arranged. In addition, 21
25 is a transfer charger, and 27 is a peeling charger.

The cleaning device 31 mainly includes a cleaning blade 66 held by a blade holder 67 and a weight 65 attached to one end of the blade holder 67.

The photosensitive drum 20. The relationship between the cleaning blade 66 and the developing roller 24A is as shown in FIG. 5, which is a plan view thereof. Both side portions are areas (non-image areas) that do not contribute to image formation. The y area of the developing roller 24A is an area where the developer is conveyed, and the length l of the cleaning blade 66 is usually longer than the length of the developing area X than the areas X and y. Here, a portion corresponding to the development area x in the longitudinal direction of the blade holder 67 and the cleaning blade 66 held therein is defined as a development corresponding area,
The remaining side portions a, a are defined as non-image corresponding areas.

Next, details of the cleaning device will be explained with reference to FIGS. 7 and 8.

In the present invention, as shown in FIG. 7(a), a blade holder 67 (67A) is a two-plate holding means.

67B) The non-image corresponding area a in the plate-shaped cleaning blade 66 held in the sandwiching part between the bent and hanging parts
, a part 66-. The hardness of 66= is changed as shown in FIG. 7(b). That is, the hardness is configured such that the hardness gradually decreases as it moves away from the boundary of the visualization corresponding area on both sides. Specifically, for example, the cleaning blade 6
When polyurethane is used as 6, it is composed of polyester as the main component, contains isocyanate, and also contains a crosslinking agent, so the mixing ratio of isocyanate, which is a curing agent, and crosslinking agent is successively equalized. It can be configured by

FIG. 8(a) shows another embodiment in which the cleaning blade 66 is made of a hard material block 6.
6A (for example, polyurethane) and material blocks 66B and 66B (for example, silicone blades) having low hardness are prepared and combined together using means such as adhesion. In this case, as shown in FIG. 5B, a hardness distribution is obtained in which the non-image corresponding areas a and a portions on both sides are lower than the hardness distribution of the image corresponding area 1 through a step. In such a case, the hardness in area a does not change sequentially depending on the distance, but if area a is further divided into a plurality of blocks and the hardness changes little by little,
Characteristics as shown in FIG. 7(b) can be obtained.

As described above, in the leaning blade 66, the contact pressure is large in the region b, which is made of a material with high hardness, but the contact pressure in the region a, which is low in hardness, is small.

Next, the operation of the device will be explained.

The photosensitive drum 20 is driven by a drive mechanism (not shown) in the direction of the arrow in synchronization with the document table 4.

Then, the original image, which is uniformly charged by the charger 21 and uniformly irradiated by the exposure lamp 22, is imaged on the photoreceptor drum 20 by the focusing light transmitter 23 to form an electrostatic latent image. . The formed electrostatic latent image is developed by the developer a-ra 24A.
The developing device 24 including the toner image is sent to the transfer charger 25 side as a toner image.

Automatically or manually fed paper P or P= is fed by a paper feeding device 26, and a toner image previously formed on the photosensitive drum 20 is transferred onto the paper P or P- by a transfer charger 25. Furthermore, the toner image is peeled off from the photoreceptor drum 20 by the peeling charger 27 using AC corona discharge, passes through the conveyance path 28, is fused and fixed onto the paper P (P') by the fixing device 29, and is removed by the ejection roller 30. It is discharged to tray 3.

On the other hand, the residual toner remaining on the photoreceptor 20 after the toner image is transferred onto the paper P (P') is removed by a cleaning device (cleaning 1).
lif) 31, and by bypass slit light 32 which branches the light from the exposure lamp 22, the potential on the photosensitive drum 20 is lowered to a partial level or below, and the next copying operation is made possible.

Here, the operation of the cleaning device will be described.

As mentioned above, this cleaning device
(P"), which is used to clean untransferred toner remaining on the photoreceptor drum 20 without being transferred to the photoreceptor drum 20. The above function is achieved by protruding in the direction opposite to direction b' and making contact.

Based on the above, the operation of the cleaning device will be explained. Since toner has been formed in the developing area X of the photosensitive drum 20 by the previous copy cycle, this acts as a lubricant, and the frictional resistance between this area and the contact surface of the cleaning blade 66 is low. Then, the non-image corresponding area iii of the cleaning blade 66
! a, The part a has a lower hardness than the area A. Therefore, the contact pressure is low, and the frictional resistance at the contact surface with the photosensitive drum 20 is also low. As a result,
Conventional problems such as curling of the blade 66 caused by large frictional stress between the blade 66 and the photoreceptor drum 20, damage to the surface of the photoreceptor drum 20, drum filming,
Image defects occur due to frictional electrification existing between the blade and the photosensitive drum 20, and furthermore, I! ! All the drawbacks such as poor cleaning and drum filming caused by lowering the blade pressure as much as possible in order to reduce the friction stress can be solved, and the original function of the cleaning device can be fully demonstrated.

Next, a case will be described in which the above-mentioned initial hitting method is used.

For example, when using the photoreceptor drum for the first time or replacing the photoreceptor drum, there is a problem that the frictional resistance increases because no lubricant is formed on the developing area. During the first rotation, toner is formed in the developing area, but no toner is formed in the non-developing area.

However, according to the present invention, since the contact pressure of the blade in the non-image corresponding area a is made different from that in the image corresponding area, the frictional stress can be reduced and the problem can be solved.

[Effects of the Invention] According to the present invention described in detail above, it is possible to provide an apparatus that has a simple configuration, can solve problems such as blade curling, poor cleaning, and filming, and can form high-quality images. .

[Brief explanation of drawings]

Fig. 1 is an external view of an apparatus according to an embodiment of the present invention, and Fig. 2 (a
) is a diagram of one mode of the operation part, and the same figure (b) is the same figure (a>
3 is a schematic sectional view of the device, FIG. 4 is a sectional view of the cleaning device and its surroundings, FIG. 5 is a plan view showing the relationship between the photosensitive drum, cleaning blade, and developing roller, and FIG. Figure 6 is a time chart of the initial setting method. Figures 7 and 8 both show an embodiment of the cleaning device of the present invention, and each figure (a > is a perspective view;
(b) is a characteristic diagram showing the relationship between hardness and contact position. 20... Image carrier, 24A... Developing roller, 67...
...Cleaning member holding means. Agent: Masayoshi Misawa, patent attorney. Figure 6 #go-=7 W, -,, B Figure 7 Figure 8 CG) (b) Figure 8 CG) (b) length

Claims (4)

[Claims] (1) In an image forming apparatus equipped with a cleaning device that performs cleaning by bringing the tip of the cleaning member into contact with the image carrier, the hardness of the cleaning member is partially varied so that the hardness of the cleaning member is adjusted in the direction of the surface in contact with the image carrier. An image forming apparatus characterized in that the contact pressure of the parts is varied depending on the position. (2) The cleaning member is characterized in that the hardness of the area corresponding to the area other than the area that contributes to image formation on the image carrier among the portions in contact with the image carrier is different from other parts. An image forming apparatus according to claim 1. (3) The image forming layer according to claim 1 or 2, characterized in that within the regions having different hardness, the hardness changes sequentially in accordance with the distance. (4) The image forming apparatus according to any one of claims 1 to 3, wherein the cleaning member is constructed by combining a plurality of blocks having different hardnesses.