JPS61240276A - 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 moving an image carrier in the backward direction at a start time by a driving means, and moving it in the forward direction after a prescribed time has elapsed. CONSTITUTION:After a prescribed time has elapsed from a copy cycle start time point, a cleaning blade 66 is pressed against a photosensitive drum 20 by operating a blade solenoid BSL, and thereafter, after another prescribed time has elapsed, a drum motor MT is rotated. Also, the motor is rotated backward (for instance, within a range in which the photosensitive drum makes one rotation) in the first stage. As a result, as soon as the rotation is executed, toner is formed in a developed image area, therefore, this toner adheres to the tip of the cleaning blade, as well, and serves as a lubricant. 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. 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, mWI such as wax in the toner used
This method has drawbacks such as poor toner fixability due to the agent and so-called filming, in which a thin toner film is formed on the photoreceptor, making the image quality highly unstable and hindering its practical use.

In addition, it has 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 maintain the thickness below about 100 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, A1, etc. (e.g., Se-based photoreceptor, Vickers hardness 5.
0 kg/111 m2), and 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 imparting such movement to the blade, there is a problem in that the accuracy of contact with the photoreceptor is likely 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 polyvinylidene fluoride (approximately 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.

[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] To achieve the above object, the present invention provides a movable image bearing member, a driving means for driving the image bearing member, and a cleaning device that performs cleaning by bringing a cleaning member into contact with the image bearing member. The image forming apparatus is characterized in that the driving means moves the image carrier in a reverse direction at startup, and moves it in a forward direction after a predetermined period of time has elapsed.

[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. Further, on the top surface of the copying machine main body 1, there is provided a document table 4 that can freely reciprocate in the left-right direction (in the direction of arrow a'). ..., exposure setting key 7a,
7b, an operation panel 10 on which input keys including a print key 8 and the like are arranged is provided.

The document table 4 has a structure including a document placing plate (glass plate) 12 on which an original [11 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). It is driven by First, a document image uniformly charged by a charger 21 and uniformly irradiated by an exposure lamp 22 is imaged on a photoreceptor drum 20 by a focusing light transmitter (trade name: Self-Oak Lens Array) 23 and static It is designed to form an electric latent image.

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.

Automatically or manually fed paper P or P' is in the paper feeder! ! The paper is fed by the photosensitive drum 20 in advance.
The toner image formed thereon is transferred onto paper P or P' by a transfer charger 25. Furthermore, it 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 then peeled off from the fixing device W! 29, the toner image is melted and fixed onto the paper P (P'), and the discharge roller 3
0, the paper is discharged onto a removable tray 3. On the other hand, after the toner image is transferred onto the paper P (P'), the photosensitive drum 20
The residual toner left on the top is removed by a cleaning device (cleaning device).
The photosensitive drum 20 is cleaned by a bypass slit light 32 obtained by branching the light from the exposure lamp 22, and the potential on the photosensitive drum 20 is lowered to a level below a certain level, making it ready for the next copying operation.

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 can 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 frame and the upper unit. It constitutes 1A. Further, each mechanism such as the paper feed cassette 2, transfer charger 25, peeling charger 27, conveyance path 28, forming guide plate 39, fixing device 29, and ejection roller pair 3o1 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 almost 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.

Note that 50.50 of the third factor is correcting the inclination of the leading edge of the paper P that is automatically fed into the paper feed cassette 2 or the paper P- that is manually fed, and the formation of 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 vapor empty switch that detects when the paper P in the paper feed cassette 2 is empty, and 55 is a developer! 24
56 is a toner cartridge, 58 is a toner concentration detector, and 59 is a developer upper cover, which prevents the document table 4 from moving unless these are closed. Further, through this opening, it is possible to replace the toner cartridge 56, replace the developing device 24, and remove the W.

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. 61 is a static elimination brush, 62 is a handle formed for opening and closing the upper unit 1A, 63 is a reflector surrounding the back of the exposure lamp 22, and 64 is 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, and a developing roller 24A is arranged on the right side of the photosensitive drum.
is arranged, and an exposure lamp 22. An optical system including a convergent light transmission body 23 and the like is arranged. Furthermore, 2
1 is a charging charger, 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 dust pan 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 developing agent 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 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, referring to FIGS. 6 and 7, the photosensitive drum 20
An embodiment of the drive unit and the blade drive unit of the cleaning device will be described.

The photosensitive drum 20 is rotationally driven by a motor MT serving as a driving source. In other words, the pulley PL1 provided on the photoreceptor drum 20 side and the pulley PL2 provided on the motor MT side.
It is driven via a belt BL installed between the two. This motor MT is constituted by, for example, a C brushless motor capable of forward and reverse rotation, and is driven by motor drive means MD. The cleaning device 31 also includes a leaning blade 66 held by a blade holder 67 that can be brought into and out of contact with the photoreceptor drum 20 , a weight 65 for adjusting the blade contact pressure, and a tip of the cleaning blade 66 that can be moved into and out of contact with the photoreceptor drum 20 . The blade solenoid BSL is driven by a solenoid drive means SD. Each of the driving means MO and SD is controlled by a control means C0NT.

The operation of the device will be explained with reference to FIG.

First, the copying operation (copy cycle) starts at time t1, and then at time t2, which is slightly delayed, the control means C0 starts.
The solenoid drive means is operated by the control signal S1 from the NT, drives the blade solenoid BSL, and brings the tip of the cleaning blade 66 into contact with the photoreceptor drum 20. At time t3, which is slightly delayed thereafter, the control means C0NT
The motor driving means MD is operated by the control signal S2 from the motor MT to rotationally drive the motor MT. Incidentally, when the motor MT rotates, the developing device operates and toner is formed on the photoreceptor. At this time, the motor driving means MD drives the motor MT in reverse rotation from the start time t3 until a time t4 after a predetermined period of time has elapsed, and thereafter drives the motor MT in forward rotation. Therefore, when the photoreceptor drum 20 is rotated in the opposite direction with the cleaning blade 66 in contact with the photoreceptor drum 20, a layer of toner is formed on the surface of the photoreceptor, and when the toner layer reaches the contact surface of the blade 66, Toner will also adhere to the tip of the blade. Therefore, during subsequent forward rotation, the single layer of toner formed on both the photoreceptor and the blade acts as a lubricant, reducing the frictional resistance between them. As a result, curling of the blade and damage to the surface of the photoreceptor and the tip of the blade can be prevented.

In the embodiment shown in FIG. 7, the cleaning blade 66 is brought into pressure contact before the photoreceptor drum 20 rotates in the reverse direction. Good too. In short, it is sufficient as long as it is before the photoreceptor drum 20 rotates in the forward direction.

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 transferred to the developing row 524A.
The toner image is sent to the transfer charger 25111 as a toner image by the developing device 24 including the 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 2o 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, the residual toner remaining on the photoreceptor 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.

Next, the operation of the cleaning device 31 and the photosensitive drum 20 will be explained.

For example, at the time of initial setting, such as when installing and using a photoreceptor drum for the first time or when replacing it with a new photoreceptor drum, toner is not formed in the developing area X of the photoreceptor drum 20. So Cleanige Blade 6
If 6 is used in pressure contact with each other, the rfJ friction resistance between the two will increase, resulting in blade curling and damage to the photoreceptor surface.

Therefore, in the present invention, as shown in FIG. 7, after a predetermined time has elapsed from the start of the first copy cycle, the blade solenoid 88L is operated to bring the cleaning blade 66 into pressure contact with the photoreceptor drum 20, and then after a predetermined time has elapsed. The drum motor MT is rotated, and the rotation of the drum motor is initially reversed (for example, within the range of one rotation of the photoreceptor drum), so that toner is formed in the developing area at the same time as the drum motor rotates. This toner also adheres to the tip of the cleaning blade 66, and the toner thus formed acts as a lubricant.

As a result, the blade 66 and the photoreceptor drum 2 are
curling of the blade 66 due to large frictional stress between the blade and the photoreceptor drum 20, damage to the surface of the photoreceptor drum 20, drum filming, image defects caused by frictional charging existing between the blade and the photoreceptor drum 20, and In order to reduce the frictional stress between the blade and drum, the blade pressure is reduced as much as possible, which can solve all the problems such as poor cleaning and drum filming, and improve the original function of the cleaning device. Can fully demonstrate.

[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, but can solve problems such as blade curling, poor cleaning, and filming, and can form high-quality images. .

[Brief explanation of the drawing]

Fig. 1 is an external view of an apparatus according to an embodiment of the present invention, Fig. 2(a)
Figure (b) is a diagram of one aspect of the operation part, and figure (a) is
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 is a schematic diagram showing the drive system of the image carrier and the cleaning device, and FIG. 7 is a time chart for explaining the operation thereof. 20... Image carrier, 24A... Developing roller, 31...
・・Cleaning device, 66・・Qing (hanging member, 67・
・・Clearing part holding means, MD・・Motor drive means, SD・・Solenoid drive means,

Claims (2)

[Claims] (1) In an image forming apparatus comprising a movable image bearing member, a driving means for driving the image bearing member, and a cleaning device for cleaning the image bearing member by bringing a cleaning member into contact with the image bearing member, the driving means is An image forming apparatus characterized in that an image bearing member is moved in a reverse direction upon startup, and moved in a forward direction after a predetermined period of time has elapsed. (2) The cleaning device has a cleaning member that can come into contact with and separate from the image carrier, and a drive means for driving the cleaning member, and the drive means moves the cleaning member to the image carrier before the image carrier starts moving in the forward direction. The image forming apparatus according to claim 1, wherein the image forming apparatus is brought into contact with a body.