JPS61240273A - 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 an elastic modulus of a cleaning member different partially, and making an abutting pressure of direction of an aubtting surface on an image carrier different in position. CONSTITUTION:The elastic modulus 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 smaller successively toward both sides from a boundary part of a developed image corresponding area (b). Toner is formed already by a copy cycle of until the previous time in a developed image area (x) of 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 elastic modulus of the non-developed image corresponding area (a), (a) parts of the cleaning blade 66 is smaller than that of the area (b), therefore, the contact pressure is low, and the frictional resistance to the photosensitive drum 20 also becomes low. In this way, rolling-up of the blade, 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 Problems Therewith] Generally, in an image forming apparatus such as an electronic copying machine, untransferred toner (developer) remaining on a photoreceptor drum serving as an image bearing member is removed by a cleaning blade (W4 cleaning member). ) so that it can be scraped off.

By the way, if a large MS 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 the study, it was found that due to curling and the electrostatic influence caused by friction, for example, a uniform surface potential could not be obtained during the charging process, resulting in image unevenness and fogging. . Further, in order to reduce the frictional force, the pressure of the cleaning blade may be reduced, but in this case, the original function of cleaning cannot be achieved, resulting in poor cleaning and 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.

It has also been known to apply a lubricant such as wax to the surface of the photoreceptor, but the thickness of the lubricant on the photoreceptor must be set to a level that does not impede the electrostatic properties of the photoreceptor. There was no way to keep the thickness below several hundred angstroms for a long period of time. Attempts have also been made to improve the blades by using materials with a lower coefficient of friction, but the problem still remains that additives reduce other properties, especially mechanical strength. In addition, conventionally, in blade cleaning type copying machines, the hardness of the photoreceptor is much smaller than that of Fe, At, etc. (e.g. Se-based photoreceptor, Vickers hardness 50 kg/
(around n+m2), when a blade or the like comes into contact with a stationary drum, a situation often arises in which the photoreceptor is deformed by pressure over time, significantly reducing 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 such movement of the blade, there is a problem that the accuracy of contact with the photoreceptor tends to be disturbed.

Additionally, during the initial installation of the photoreceptor drum, there are cases in which operators or service personnel generally scatter lubricating powder such as polynylidene fluoride with a thickness of about 5 μm on the drum to reduce the friction between the drum and the blade. but,
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, the frictional resistance is still large, and there is a problem in that the blade turns over and damages 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 1 To achieve the above object, the present invention provides a method for cleaning an image carrier by bringing the tip of the cleaning member into contact with the image carrier. 2 In an image forming apparatus equipped with a leaning device, the elastic modulus of the cleaning member is This is characterized in that the abutting pressure in the direction of the abutting surface against the image carrier is varied depending on the position by partially varying the abutment pressure.

[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. A paper feed cassette 3 is a paper discharge tray mounted on the left side of the main body 1 of the copying machine. In addition, a document table 4 is provided on the construction surface of the copying machine main body 1, which is capable of reciprocating in the left and right direction (arrow a). Numeric keypad 6..., exposure setting key 7a
, 7b, a print key 8, and other input keys are arranged thereon.

The document table 4 has a structure including a document placing plate (glass plate) 12 on which an original 111 is placed and a document cover 13 covering the upper surface thereof.

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
is the power 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. The photoreceptor drum 20 is synchronized with the document table 4 in the direction of the arrow by a drive mechanism (not shown). 1 is driven. First, a document image uniformly charged by a charger 21 and uniformly irradiated by an exposure lamp 22 is transferred to a photoreceptor drum 20 by a focusing light transmitter (trade name: Self-Oak Lens Array) 23.
An electrostatic latent image is formed by forming an image on the object.

The formed electrostatic latent image is transferred to a developing device including the developing roller 24A.
24, the toner image is sent to the transfer charger 25 side.

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 a peeling charger 27 using AC corona discharge, passes through a conveyance path 28, and is melted and fixed onto the paper P (P') by a fixing device 29, and is then moved to a tray that can be attached or removed by an ejection roller 30. It is discharged at 3. On the other hand, for
'After the toner image is transferred onto the paper P (P-), the residual toner remaining on the photosensitive drum 20 is cleaned by a cleaning device (cleaning device) 31, and bypass slit light is produced by branching the light from the exposure lamp 22. 32, the photoreceptor drum 2
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 20. Each device such as a cleaning device 31 and a static elimination lamp 32 is attached by appropriate means, and a fan 33 as a cooling device, a paper feed roller 38 of a paper feed device [26], and a document table 4 are also attached to the above frame and mounted on the upper part. It constitutes unit 1A. In addition, each mechanism such as the paper feed cassette 2, the transfer charger 25, the peeling charger 27, the conveyance path 28, the forming guide plate 39, the fixing device 29, the ejection roller pair 301 and the tray 3 is attached by appropriate means to form the lower unit 1B. It consists of After the front cover 1a of the copying machine main body 1 is rotated and removed, it can be opened and closed approximately along the transport path 28 of the paper P (P') via a housing opening/closing device (not shown). Therefore, even if the 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 the automatically fed paper P or the 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 paper to the transfer charger 25, and 51 is a paper detection switch disposed immediately before the pair of registration rollers 50 and 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 upper cover of the developer, which prevents the document table 4 from being touched if it is not 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. This is an area (non-image area) that does not contribute to image formation. The y area of the developing roller 24A is an area where the developer is conveyed, and the length of the cleaning blade 66 is usually longer than the length of the developing area X. Here, a portion of the blade holder 67 and the cleaning blade 66 held therein in the longitudinal direction corresponding to the image development region X is defined as a development region, and the remaining both side portions a and a are defined as non-development region. Define.

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.

The elastic modulus of the non-image corresponding area a, a portion 66", 66- of the plate-shaped cleaning blade 66 held in the clamping part between the bent and hanging parts of 67B) is shown in FIG. 7(b).
It is changed as follows. In other words, the elastic modulus is configured to decrease sequentially as the distance from the boundary of the image corresponding area to both sides increases. Specifically, for example, when polyurethane is used as the cleaning blade 66, it is composed of polyester as a main component, contains isocyanate, and also contains a crosslinking agent. It can be constructed by sequentially increasing the ratios.

FIG. 8<a) shows another embodiment in which the cleaning blade 66 is made of a material block 66A having a large elastic modulus (for example, polyurethane) and a material block 668, 66B having a small elastic modulus (for example, a silicone blade). are prepared and combined together using means such as adhesion. In this case, as shown in FIG. 6(b), a distribution is obtained in which the non-image corresponding areas a and a portions on both sides are smaller with respect to the elastic coefficient distribution of the image corresponding area 1 through a step. In such a case, the elastic modulus does not change sequentially according to the distance in region a, but if the region a is further divided into a plurality of blocks and configured so that the modulus changes little by little, as shown in FIG. The characteristics shown in (b) can be obtained.

As described above, in the leaning blade 66, the contact pressure is large in the b region made of a material with a large elastic modulus, but
The contact pressure in region a, where the elastic modulus is small, is small.

Next, the operation of the device will be explained.

The photosensitive drum 20 is moved in the direction of arrow b' by a drive mechanism (not shown).
direction 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 transferred to the developing roller 24A.
The toner image is sent to the transfer charger 25 side as a toner image by the developing device [24 including the toner image].

A sheet P or P' that is automatically or manually fed is fed by a sheet feeding device 26, and a toner image previously formed on the photosensitive drum 20 is transferred onto the sheet P 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, and is melted and fixed onto the paper P (Pl) by a fixing device [29. is discharged.

On the other hand, residual toner remaining on the photoconductor 20 after the toner image is transferred onto the paper P (P-) is cleaned by a cleaning device (cleaning device) 31, and bypass slit light obtained by branching the light from the exposure lamp 22 is removed. 32, the photoreceptor drum 2
The potential above 0 is partially lowered to below the level to make the next copy operation 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 on the photosensitive drum 20 by the previous copy cycle, this acts as a lubricant, and the frictional resistance of the contact surface between this area and the cleaning blade 66 is low. and the non-image corresponding area a of the cleaning blade 66;
Portion a has a smaller elastic modulus than region A.

Therefore, the contact pressure is low and the photosensitive drum 20
The frictional resistance at the contact surface is also reduced. As a result, the blade 66 curls up, the surface of the photoreceptor drum 20 is damaged, drum filming occurs, and the friction between the blade and the photoreceptor drum 20 occurs due to the large frictional stress between the blade 66 and the photoreceptor drum 20 as in the conventional case. Image defects are caused by frictional charging that exists between the blade and the drum, and cleaning defects are caused by reducing the blade pressure as much as possible in order to reduce the frictional stress between the blade and the drum.

All drawbacks such as drum filming 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 setting 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)
FIG. 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 among the photosensitive drum, cleaning blade, and developing roller, and FIG. The figure shows a time chart of the initial setting method, and FIGS. 7 and 8 both show an embodiment of the cleaning device of the present invention. Each figure (a) is a perspective view,
(b) is a characteristic diagram showing the relationship between the elastic modulus and the contact position. 20... Image carrier, 24A... Developing roller, 31...
. . . Cleaning device, 66 . . . Cleaning member, Figure 6 No. ■ roller 1. −． ．． ．． B Figure 7(b) Figure 8(b)

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 elastic modulus of the cleaning member is partially varied to improve the contact surface to the image carrier. An image forming apparatus characterized in that the contact pressure in the direction is varied depending on the position. (2) The cleaning member is characterized in that, of the contact portion with the image carrier, the elastic modulus of the range corresponding to the area other than the portion contributing to image formation on the image carrier is different from that of other portions. An image forming apparatus according to claim 1. (3) The image forming layer according to claim 1 or 2, wherein the elastic modulus changes sequentially in areas having different hardness in accordance with 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 elastic modulus.