JPH0337693A - Image forming device - Google Patents

Abstract

PURPOSE:To clean an endless belt without developing the dislocation of transfer images and synchronizing drift by bringing a driving roller into press-contact with the endless belt downstream of a position in which a cleaning member comes into contact with the endless belt, before the member is brought into contact with the endless belt, and thereby driving the endless belt at a speed the same as its moving speed. CONSTITUTION:The driving roller 20 can rotate at a velocity the same as the moving speed of the endless belt 10. The roller 20 is disposed in the moving direction of the endless belt 10, downstream of the position in which the cleaning member 15 comes into contact with the endless belt 10, so that the roller can be position-switched between the position in which the roller is in press-contact with the endless belt 10 and the position in which the roller is separated from the endless belt 10. Before the cleaning member 15 is brought into contact with the endless belt 10, the driving roller 20 is brought into press-contact with the endless belt 10 downstream of the contact position, and the endless belt 10 is driven at the speed the same as its moving speed. Consequently, the influence of the load fluctuation of the endless belt 10, which is caused by the contact and separation of the cleaning member 15, is eliminated. Thus, the endless belt can be cleaned without developing the dislocation of transfer images and synchronizing drift.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus, and particularly to an image forming apparatus that is equipped with an image bearing member such as a photoreceptor or an intermediate transfer member consisting of an endless belt, or a transfer paper support, and that is equipped with an endless belt. The present invention relates to an image forming apparatus having a cleaning device that removes residual toner by bringing a cleaning member into contact with a belt.

(Prior Art) Conventionally, an image forming apparatus that primarily transfers an image formed on a photoreceptor to an intermediate transfer member and then secondarily transfers it to a transfer paper has been disclosed, for example, in Japanese Patent Application Laid-open No. 155232/1983. It is known from Japanese Unexamined Patent Publication No. 56-147166, etc., and has flexibility as an intermediate transfer body! It is also known to consist of a belt.

Further, an image forming apparatus having a photoreceptor made of an endless belt is also known.

Furthermore, Japanese Utility Model Application Publication No. 62-84072 discloses a method in which a transfer paper is supported on a transfer paper support made of an endless belt and transferred to a transfer section, and the toner image on a photoreceptor is transferred to the transfer paper. An image forming apparatus is disclosed.

In these image forming apparatuses, the toner remaining on the endless belt is usually removed by bringing a cleaning member into contact with the endless belt.

(Problem to be Solved by the Invention) However, when the cleaning member is brought into contact with or separated from the endless belt in order to remove the residual toner on the endless belt, the load acting on the endless belt fluctuates greatly. Fluctuations in the rotational speed of the rollers that drive the endless belt, slips between the rollers, etc. may cause uneven feeding on the endless belt or cause the endless belt to expand or contract.
As a result, there are problems in that a transferred image is misaligned, and a synchronization difference occurs between a photoreceptor, an intermediate transfer belt, a transfer paper, and the like.

On the other hand, in the above-mentioned Japanese Utility Model Publication No. 62-84072, in order to avoid such problems, cleaning is performed at times other than when forming an image, but this results in an image formation prohibition time and reduces the cost per unit time. There is a problem that the number of images formed on the paper decreases and it becomes inconvenient when used.

In view of the above-mentioned conventional problems, the present invention cleans an image carrier or a transfer material support made of an endless belt without causing misalignment or synchronization of transferred images, and without any image formation inhibition time. The purpose is to provide an image forming apparatus that can perform

(Means for Solving the Problems) In order to achieve the above object, the image forming apparatus of the present invention includes an image carrier or a transfer paper support made of an endless belt, and a residual toner on the endless belt. In an image forming apparatus equipped with a cleaning member that contacts and removes, the cleaning member is rotatable at a circumferential speed equal to the moving speed of the endless belt at a position downstream in the moving direction of the endless belt from the contact position of the cleaning member with respect to the endless belt. The present invention is characterized in that the driving roller is arranged so as to be switchable between a position in which it is in pressure contact with the endless belt and a position in which it is separated from the endless belt.

(Function) According to the above configuration of the present invention, when the cleaning member is brought into contact with the endless belt, before that, the driving roller is brought into pressure contact with the endless belt at a position downstream of the contact position, and the endless belt is moved at a speed equal to the moving speed of the endless belt. By driving at high speed, it is possible to eliminate the influence of load fluctuations on the endless belt due to contact and separation of the cleaning members, and even during image formation, there is no possibility of misalignment or synchronization of transferred images. An endless belt used as an image carrier or a transfer material support can be cleaned without any cleaning.

(Embodiment) An embodiment in which the present invention is applied to a color copying apparatus will be described below with reference to FIGS. 1 to 5.

In FIG. 1, reference numeral 1 denotes a document table glass on which a document is placed. Below the document table glass 1, there are a commercial light lamp 2, first to fifth lenses 3a to 3e, a lens 4, and a color separation filter. An optical system consisting of unit 5 is provided. As shown in FIG. 3, the color separation filter unit 5 includes a blue filter plate 5B, a green filter plate 5G, and a green filter plate 5R, which are supported by a frame 51 in parallel, and are connected to a drive motor 52 and a position sensor. 53a, 53b
The structure is such that one of the filter plates 5B, 5G, and 5R can be selectively positioned in the exposure optical path.

6 is a photosensitive drum, around which are an erase lamp 7, a charger 8, a developing section 9, and an intermediate transfer belt 10.
, a drum cleaner 11 are provided. The developing section 9
A yellow developer 9Y, a magenta developer 9M, and a cyan developer 9C are installed. Further, each developing device is equipped with a developing sleeve, a grain cutting shutter, a toner concentration detector, a toner replenishing device, and the like.

The intermediate transfer belt 10 is made of a flexible semiconductor with good environmental resistance, for example, a volume resistivity of lXl0'' to lXl0''Ω.
The thickness is 0.6 cm and is made of polyurethane rubber, etc.
It is made up of an endless belt with a diameter of about mm.

Around this intermediate transfer belt 10, there is a primary transfer charger 12 that transfers an image from a photoreceptor drum to the intermediate transfer belt 10, a secondary transfer charger 13 that transfers an image from the intermediate transfer belt 10 to a transfer material, and a static elimination charger 14. , belt cleaner 15, etc. are provided.

Further, as shown in detail in FIG.
．． 17, a secondary transfer roller 18, and a heald cleaner roller 19.

The intermediate transfer belt (10) can be rotated by being pinched between the belt cleaner roller (19) and the intermediate transfer belt (10) at a position downstream in the moving direction of the intermediate transfer belt (10) from the contact position of the belt cleaner (15) with respect to the intermediate transfer belt (10), and Drive motor 21
A drive roller 20 is provided which is rotated at a circumferential speed equal to the moving speed of the intermediate transfer heald 10 . The drive roller 20 is made of a material that can reliably drive the intermediate transfer roller 10 made of polyurethane without slippage, such as chloroprene rubber having a hardness of about 60°. Further, the drive roller 20 is attached to the tip of the swing arm 21 so as to be switchable between a position in which it is in pressure contact with the intermediate transfer belt 10 and a position in which it is separated from the intermediate transfer belt 10, and is moved toward the pressure contact position by a tension spring 23. It is configured to be energized and to be separated by a solenoid 24.

Further, a sensor 25 for detecting the rotational position of the intermediate transfer belt 10 is disposed at one end of the shaft of the pressure roller 16 . This sensor 25 is composed of a pulse blade JTi 25a provided at the end of the shaft for cutting off the optical path, and an optical sensor 25b.

26 is a support arm that supports the belt cleaner 15 in a movable manner between a cleaning position where it is in contact with the intermediate transfer belt 10 and a retracted position where it is separated; 27 is a tension spring that biases the belt cleaner 15 toward the retracted position; and 28 is a tension spring that is biased toward the retracted position; This is a solenoid that switches to the cleaning position.

Drive motor 21 for the drive roller 20, drive roller 2
0 position switching solenoid 24 and belt cleaner 1
As shown in FIG. 4, the No. 5 position switching solenoids 28 are driven and controlled by the CPU 30, which controls the entire copying apparatus, via respective drive circuits 31, 32, and 33.

Therefore, the CPU 30 is manually supplied with a detection signal from the sensor 25 that detects the rotational position of the intermediate transfer bell 10, that is, the image position.

In FIG. 1, 40 is a paper feed cassette, 41 is a register 1
42 is a transfer paper conveyance belt, 43 is a fixing device equipped with a fixing roller with a built-in heater, and 44 is a paper discharge tray.

Next, the operation will be explained. The original placed on the original table glass 1 is sequentially scanned in the horizontal direction, and the reflected light is
~Third mirrors 3a to 3c, color separation filter unit 5,
An image is formed on the photosensitive surface of the photosensitive drum 6 via the lens 4 and the fourth and fifth mirrors 3d and 3e. Photosensitive drum 6
After being exposed and neutralized by the erase lamp 7, it is charged to, for example, a constant negative potential by the charger 8, and is rotated and exposed in synchronization with the scanning.

When the photosensitive surface is irradiated with reflected light from the original, the surface potential changes depending on the intensity of the light, and an electrostatic latent image is formed.

This electrostatic latent image is formed by the yellow developing device 9Y of the developing section 9,
The image is developed with toner of each color in either the magenta developer 9M or the cyan developer 9C. for example,
In the color separation filter unit 5, when the blue filter plate 5B is located in the optical path, the yellow developer 9Y, which is a complementary color to blue, is selected, and in the other developers 9M and 9C, the ear cutter shutter at the rear of each developer sleeve is selected. After the developer on the developing sleeve is scraped off, the yellow developing device 9Y is driven, and the electrostatic latent image is developed with yellow toner and made visible. Note that the toner is stored on the photoreceptor drum 6.
It is charged to the opposite potential, for example, to a positive potential.

The intermediate transfer belt IO is driven at the same speed as the photoreceptor drum 6 in synchronization with the photoreceptor drum 6, and the photoreceptor drum 6 is driven by the primary transfer charger 12 to which a negative potential is applied.
The upper positive potential toner image is transferred onto this intermediate transfer belt 10 . (After that, the photosensitive surface of the photosensitive drum 6 is cleaned by a drum cleaner 11, and the exposure-development and primary transfer steps are completed.

In the case of full-color copying, when the first exposure, development and primary transfer steps for yellow are completed, the green filter plate 5 is placed in the color separation filter unit 5.
G is selected and positioned on the optical path, and the photosensitive surface of the photosensitive drum 6 is exposed by the reflected light of the original that passes through it, forming an electrostatic latent image, which is visualized by the magenta developer 9M, which is a complementary color to green. Then, a magenta toner image is transferred to be superimposed on the yellow toner image on the intermediate transfer heald 10.

When the second exposure-development and primary transfer process is completed,
For the third time, the second filter plate 5R in the color separation filter unit 5 is selected and positioned on the optical path, and the light reflected from the original that passes through it exposes the photosensitive surface of the photosensitive drum 6, forming an electrostatic latent image. The cyan toner image is formed and visualized by the cyan developer 9C, which is a complementary color of red, and the cyan toner image is transferred onto the intermediate transfer belt 10, overlapping the yellow and magenta toner images, and these full-color toners of yellow, magenta, and cyan are formed. An image is formed.

During this next transfer process, the heald cleaner 15 of the intermediate transfer belt 10 is separated from the intermediate transfer belt 10 because the solenoid is turned off on the second day. Further, the drive roller 20 is also separated from the intermediate transfer belt 10 due to the solenoid 24 being turned on.

On the other hand, the position of the intermediate transfer belt 10 is detected by the sensor 25, and at a predetermined timing based on the detection signal, the transfer paper is fed out from the paper feed cassette 40 by the paper feed roller 40a and sent to the registration roller 4I. Secondary transfer charger 1 at predetermined timing with registration roller 4I
The transfer paper is sent out toward the intermediate transfer belt 10 at the secondary transfer charge roller 3 to which a negative potential is applied.
The upper positive potential full-color toner image is electrostatically attracted and secondarily transferred to the transfer paper.

The transfer paper on which the toner image has been transferred is charged with an alternating current potential by the charger I4, and the intermediate transfer bell) 10
The paper is separated, transported by suction by a transfer paper conveyance belt 42, sent to a heated fixing device 43 to be fixed, and then discharged onto a paper discharge tray 44.

On the other hand, the intermediate transfer belt 10 that has completed the secondary transfer is cleaned by the belt cleaner 15, and then the primary transfer process for the first color of the next image is started.

Here, the cleaning process of the intermediate transfer belt 10 will be explained in detail based on FIG. 5. When the leading edge position of the image passes the secondary transfer position, before reaching the belt cleaner 15, the drive motor 21 is first driven to transfer the drive roller 20.
is rotated at the same circumferential speed as the intermediate transfer belt 10, and then the solenoid 24 is turned off so that the drive roller 20 is pressed against the intermediate transfer belt 10 by the urging force of the tension spring 23, and then the solenoid 28 is turned on and the belt is rotated. Cleaner 1
5 is brought into pressure contact with the intermediate transfer belt 10, residual toner on the intermediate transfer belt 10 is removed. At this time,
A load acts on the intermediate transfer belt 10, and this intermediate transfer belt 10 has a belt cleaner roller 19 and a drive roller 2.
Since the intermediary transfer belt 10 is sandwiched between the intermediate transfer belt 10 and the intermediary transfer belt 10 and is reliably driven, uneven feeding due to slipping of the intermediary transfer belt 10, etc.
No expansion or contraction of 0 occurs, and image shift and synchronization shift can be reliably prevented.

Next, after an appropriate period of time after the trailing edge position of the image has passed the belt cleaner 15, the belt cleaner 15 is retracted in the reverse order to the above, the drive roller 20 is retracted, and the drive motor 21 is then stopped. Belt cleaner 15
The running of the intermediate transfer bell (10) is not affected even when the intermediate transfer bell (10) is detached.

As described above, cleaning can be performed by the belt cleaner 15 without affecting the exposure, development, and transfer processes.

In the above embodiment, an example of a belt cleaner using a blade method is shown, but other cleaning methods such as a fur brush cleaner can be similarly configured. Furthermore, the present invention is not limited to cleaning intermediate transfer belts, but can also be applied to cleaning photoreceptors made of endless belts, transfer paper supports, and the like.

(Effects of the Invention) According to the image forming apparatus of the present invention, as is clear from the above description, when the cleaning member is brought into contact with the endless belt, before that, the driving roller is placed at a position downstream of the contact position of the cleaning member. By pressing the endless belt against the endless belt and driving the endless heald at a speed equal to the moving speed of the endless belt, it is possible to eliminate the influence of load fluctuations on the endless heald due to contact and separation of the cleaning member, and therefore, even during image formation, the transferred image This provides the effect that the endless belt, which serves as an image carrier and a transfer material support, can be cleaned without causing any deviation or synchronization.

[Brief explanation of drawings]

FIGS. 1 to 5 show an embodiment in which the present invention is applied to a full-color copying apparatus, in which FIG. 1 is a general schematic diagram, FIG. 2 is a perspective view of the intermediate transfer belt, and FIG. 3 is a color separation diagram. FIG. 4 is a perspective view of the filter unit, FIG. 4 is a block diagram showing a schematic configuration of the main parts of the control section, and FIG. 5 is a timing diagram of the operation. 6.-1--
Intermediate transfer belt 5 0 1 2 3 4 Belt cleaner drive roller --- Drive motor swing arm tension spring solenoid

Claims (1)

[Claims] (1) Cleaning of the endless belt in an image forming apparatus comprising an image carrier or a transfer paper support made of an endless belt, and a cleaning member that contacts the endless belt to remove residual toner on the endless belt. At a position downstream in the direction of movement of the endless belt from the contact position of the members,
An image forming apparatus characterized in that a drive roller rotatable at a circumferential speed equal to the moving speed of the endless belt is disposed so as to be switchable between a position in pressure contact with the endless belt and a position away from the endless belt.