JPS61240275A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent blade rolling-up, cleaning failures, a filming, etc. by controlling a moving speed of an image carrier by a movement control means of the image carrying body. 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 after a prescribed time has elapsed, a drum motor MT is rotated. The rotation of the motor is controlled so that a rotating speed increases (or decreases) gradually in a prescribed period of a start time and a stop time, and accordingly, even if the blade 66 is pressed against the photosensitive drum 20, a shock of the start time can be softened. Also, toner is supplied as soon as the photosensitive drum is rotated, therefore, the toner is formed on the surface of the photosensitive body, it serves as a lubricant between the photosensitive body and the cleaning blade, and the start and stop are executed smoothly. 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, untransferred toner (developer) remaining on a photoreceptor dome serving as an image bearing member is removed using a cleaning blade (cleaning blade). material) so that it can 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 is not created during the charging process, resulting in uneven images 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.

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.
When a blade or the like comes into contact with a stationary drum, the photoreceptor often deforms due to 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 tram zone 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 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.

[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 includes a movable image carrier, a control means for controlling the movement of the image carrier, and a cleaning member that is brought into contact with the image carrier to perform cleaning. In the image forming apparatus equipped with a cleaning device, the control means controls the moving speed of the image carrier.

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 C 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 and right direction (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 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
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, an original 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.

The automatically or manually fed paper P or P' is fed by a paper feeder [26], and the toner image previously formed on the photosensitive drum 20 is transferred onto the paper P or P' by the 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 the paper P (PM) by a fixing device 29, and is transferred to a removable tray 3 by an ejection roller 30. On the other hand, paper P (P
After the toner image is transferred onto the photoreceptor drum 20, the residual toner remaining on the photoreceptor drum 20 is cleaned by a cleaning device (cleaning device) 31, and the photoreceptor drum 20 is cleaned by bypass slit light 32, which is a branched light from the exposure lamp 22. The upper potential is lowered to a partial level or lower to make the next copy operation possible.

Further, a fan 33 serves as a cooling unit and exhausts heat generated from the heat generating unit 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 W131 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, 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 Then, the front cover 1a of the copying machine main body 1
After rotation and removal, the paper P (P') can be opened and closed almost along the transport path 28 of the paper P (Pl) via a housing opening/closing device (not shown). Even if paper gets jammed, it can be easily retrieved.

In addition, 50.50 in FIG. 3 corrects 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 also 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 vapor 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 a developer 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. 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
Reference numeral 1 designates a charging charger 25 as a transfer charger, and 27 as 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 X 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 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 2o
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 PLI 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 MD and SD is controlled by a control means C0NT.

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

First, a copying operation (copy cycle) starts at time t1, and then at a slightly delayed time [2, the control means C0
The solenoid driving means is operated by the control signal @S 1 from the NT to drive the blade solenoid BSL and bring the tip of the cleaning blade 66 into contact with the photosensitive drum 20 . At time t3, which is slightly delayed thereafter, the control means C0N
The motor driving means MD is operated by the control signal $2 from T, and rotationally drives the motor MT. Note that when the motor MT is rotating, toner is already formed on the photoreceptor due to the operation of the developing device. The motor driving means MD gradually increases the rotational speed of the motor MT from the time of starting the motor [3 until time t4 when a predetermined period of time has elapsed, and after time t4, the motor MT is driven to rotate at a constant speed. There is. This is, for example, a rotation control method such as PLL (phased,
If the locked, loop) system is used, the number of rotations can be determined according to the fundamental frequency, so the drive control described above can be performed by gradually increasing the fundamental frequency.

Although the drum is rotated after the blade is pressed in FIG. 7, the blade may be pressed while the photosensitive drum starts to slowly rotate.

With the above-described apparatus, when the cleaning blade 66 is pressed against the photoreceptor drum 20, a sudden sudden frictional resistance is generated, or when the cleaning blade 66 is already pressed against the photoreceptor drum 20, the photoreceptor drum 20 is pressed. Even if a sudden frictional resistance is generated when the 20 starts rotating, the rotation at the time of startup becomes gentle, which prevents the blade from turning over and damaging the photoreceptor surface and blade. .

Next, the operation of the device will be explained.

The photosensitive drum 20 is moved in the direction of arrow b' by a drive structure (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 developing device 24 including the toner image is sent to the transfer charger 25 side as a 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, is fused and fixed onto the paper P (PM) by a fixing device @29, and is transferred to an escape hole tray 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 the drum is rotated rapidly while the drum is in pressure contact with the drum, or if the blade is suddenly brought into pressure contact while the drum is rotating, the frictional resistance between the two will suddenly increase, which may cause the blade to roll over or damage the photoreceptor surface. Become.

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 BSL 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 speed of the drum motor is controlled to gradually increase (or decrease) during a predetermined period when starting and a predetermined period when stopping. Therefore, even if the cleaning blade 66 is pressed against the photosensitive drum 2o, the impact at the time of startup can be alleviated. In addition, since toner is supplied simultaneously with the rotation of the photoreceptor drum, toner is formed on the surface of the photoreceptor.
This acts as a lubricant between the cleaning blade and smooth startup and shutdown.

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 the drum, the blade pressure is reduced as much as possible, which can solve all the drawbacks of 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, 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, 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, and FIG. 4 is a partially enlarged view of the cleaning l! ! 5 is a plan view showing the relationship among the photosensitive drum, cleaning blade, and developing roller; FIG. 16 is a schematic diagram showing the drive system of the image carrier and the cleaning device; FIG. This is a time chart i for explaining the operation. 2019. Image carrier, 24 A-...Development o-7, 31
...Cleaning device, 6609. Cleaning parts, 67・
...Cleaning member holding means, MD...Motor drive means, SD...Solenoid drive means, 0 pieces

Claims (2)

[Claims] (1) In an image forming apparatus comprising a movable image carrier, a control means for controlling movement of the image carrier, and a cleaning device for cleaning the image carrier by bringing a cleaning member into contact with the image carrier, An image forming apparatus characterized in that the means controls the moving speed of the image carrier. (2) The image forming apparatus according to claim 1, wherein the control means sets the speed of the image carrier at a low speed when it is activated, and sets the speed to a constant speed after a predetermined period of time has elapsed.