JP2794803B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus provided with an image carrier or a transfer support such as a photoconductor or an intermediate transfer body composed of an endless belt, and The present invention relates to an image forming apparatus having a cleaning member for contacting and cleaning the endless belt.

(Prior Art) Conventionally, an image forming apparatus in which an image formed on a photoreceptor is primary-transferred to an intermediate transfer body and then secondary-transferred to transfer paper is disclosed in, for example, Japanese Patent Application Laid-Open No. 50-155232 and JP 56
No. 147166 is known, and an intermediate transfer member including a flexible endless belt is also known.

Further, an image forming apparatus having a photoconductor composed of an endless belt is also known.

Further, Japanese Utility Model Application Laid-Open No. 62-84072 discloses that a transfer paper is supported on a transfer paper support consisting of an endless belt, transferred to a transfer section, and the toner image on the photoreceptor is transferred to the transfer paper. An image forming apparatus is disclosed.

In these image forming apparatuses, toner, paper powder, and the like remaining on the endless belt are usually removed by bringing a cleaning member into contact with the endless belt.

(Problems 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 and paper dust on the endless belt, a load acting on the endless belt is increased. The endless belt fluctuates greatly, causing fluctuations in the rotation speed of the roller that drives the endless belt, slippage with this roller, etc., resulting in uneven feeding of the endless belt or expansion and contraction of the endless belt. And there is a problem that a synchronization shift occurs between the photoconductor, the intermediate transfer belt, the transfer paper, and the like.

On the other hand, in Japanese Utility Model Application Laid-Open No. 62-84072, in order to avoid such a problem, cleaning is performed at times other than the time of image formation. There is a problem that the number of formed images is reduced and inconvenience is felt during use.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention can clean an image carrier or a transfer material support made of an endless belt without causing a shift or a synchronization shift in a transferred image and without an image formation prohibition time. An image forming apparatus is provided.

(Means for Solving the Problems) As a specific means for achieving the above object, the present invention relates to an image carrier or a transfer paper support comprising an endless belt which is driven to rotate, and which is in contact with the endless belt. An image forming apparatus comprising: a cleaning member movable between a cleaning position and a separated retreat position; wherein the endless belt is moved to a position downstream of a contact position of the cleaning member with respect to the endless belt in a moving direction of the endless belt. A drive roller rotatable at a peripheral speed equal to the speed is disposed so as to be switchable between a position pressed against the endless belt and a position separated therefrom, and the cleaning member is moved from the retracted position to the cleaning position. Before the endless belt is brought into contact with the endless belt, the drive roller is rotated at a peripheral speed equal to the moving speed of the endless belt, And press-contact.

According to the above configuration of the present invention, when the cleaning member is brought into contact with the endless belt, before that, by driving the drive roller to the endless belt at a position downstream of the contact position at a speed equal to the moving speed thereof, the driving roller is brought into pressure contact with the endless belt. The load fluctuation of the endless belt due to the contact and separation of the cleaning member can be eliminated, and even during the image formation, the transfer image does not shift or the synchronization shift does not occur. The endless belt as a transfer material support can be cleaned.

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

In FIG. 1, reference numeral 1 denotes a platen glass on which a document is placed. Below the platen glass 1, an exposure lamp 2,
An optical system including first to fifth mirrors 3a to 3e, a lens 4, and a color separation filter 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 red filter plate.
5R are supported by the frame 51 in a parallel state, and the filter plates 5B, 5B are driven by the drive motor 52 and the position sensors 53a, 53b.
It is configured so that one of G and 5R can be selectively positioned in the exposure light path.

Reference numeral 6 denotes a photosensitive drum, around which an erase lamp 7, a charging charger 8, a developing unit 9, and an intermediate transfer belt 1 are provided.
0, a drum cleaner 11 is provided. The developing unit 9
Is provided with a yellow developing unit 9Y, a magenta developing unit 9M, and a cyan developing unit 9C. Each developing unit is provided with a developing sleeve, a cutting shutter, a toner concentration detector, a toner replenishing device, and the like.

The intermediate transfer belt 10 is a semiconductor having good environmental resistance and flexibility, for example, having a volume resistance of 1 × 10 ¹⁰ to 1 × 10 ¹² Ω _- cm.
It is composed of an endless belt of about 0.6 mm made of polyurethane rubber or the like.

Around the intermediate transfer belt 10, a primary transfer charger for transferring an image from the photosensitive drum to the intermediate transfer belt 10 is provided.
12, a secondary transfer charger 13 for transferring an image from the intermediate transfer belt 10 to a transfer material 13, a static elimination charger 14, a belt cleaner
15 mag are provided.

As shown in detail in FIG. 2, the intermediate transfer belt 10 has pressing rollers 16 and 17 on both sides of the primary transfer charger 12.
, The secondary transfer roller 18 and the belt cleaner roller 19
It is stretched by a straight roller.

At a position on the downstream side in the moving direction of the intermediate transfer belt 10 from a contact position of the belt cleaner 15 with the intermediate transfer belt 10, the intermediate transfer belt 10 can be rotated by pressing the intermediate transfer belt 10 between the belt cleaner roller 19 and a driving motor. At 21, there is provided a drive roller 20 whose peripheral speed is rotationally driven at a speed equal to the moving speed of the intermediate transfer belt 10. The drive roller 20 is made of a material that can be reliably driven without slippage with respect to the intermediate transfer belt 10 made of polyurethane, for example, chloroprene rubber having a hardness of about 60 °. or,
The drive roller 20 is mounted on the distal end of the swing arm 21 so as to be switchable between a position pressed against the intermediate transfer belt 10 and a position separated from the intermediate transfer belt 10, and is urged toward the pressed position by a tension spring 23. And separated by a solenoid 24.

A sensor 25 for detecting the rotational position of the intermediate transfer belt 10 is provided at a shaft end on one end side of the pressing roller 16. The sensor 25 includes a pulse blade 25a for interrupting an optical path provided at a shaft end and an optical sensor 25b.

26 is a support arm that movably supports the belt cleaner 15 between a cleaning position in contact with the intermediate transfer belt 10 and a retracted position separated from the intermediate transfer belt 10, 27 is a tension spring that urges the retracted position, and 28 is a biasing force. A solenoid that switches to the cleaning position in opposition.

A drive motor 21 for the drive roller 20, a solenoid 24 for switching the position of the drive roller 20 and a solenoid 28 for switching the position of the belt cleaner 15 are provided to a CPU 30 for controlling the entire copying apparatus as shown in FIG. Drive circuits 31, 3
Drive control is performed via 2 and 33. Therefore, the CPU 30
A detection signal from a sensor 25 for detecting the rotational position of the intermediate transfer belt 10, that is, the image position, is input.

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

Next, the operation will be described. The original placed on the platen glass 1 is sequentially scanned in the horizontal direction, and the reflected light is reflected by first to third mirrors 3a to 3c, a color separation filter unit 5, a lens 4, and fourth and fifth mirrors 3d. An image is formed on the photosensitive surface of the photosensitive drum 6 via 3e. After the photoreceptor drum 6 has been subjected to exposure and elimination by the erase lamp 7, the photoreceptor drum 6 is charged to, for example, a negative constant potential by the charging charger 8, and is rotated and exposed in synchronization with the scan. When the photosensitive surface receives the reflected light from the document, the surface potential changes according to the intensity of the light, and an electrostatic latent image is formed.

This electrostatic latent image is stored in a yellow developing unit 9Y of the developing unit 9;
Each of the magenta developing device 9M and the cyan developing device 9C develops with each color toner. For example, in the color separation filter unit 5, if the blue filter plate 5B is located in the optical path, the yellow developing device 9Y which is a complementary color of blue
Is selected, and in the other developing units 9M and 9C, after the developer on the developing sleeve is scraped off by the cutting edge shutters behind the respective developing sleeves, the yellow developing unit 9Y is driven, and the electrostatic latent image is formed by the yellow toner. The image is developed and visualized. Note that the toner is charged to, for example, a positive potential opposite to the photosensitive drum 6.

The intermediate transfer belt 10 is driven at the same speed as the photosensitive drum 6 in synchronization with the photosensitive drum 6, and a positive potential toner image on the photosensitive drum 6 is formed by the primary transfer charger 12 to which a negative potential is applied. The image is transferred to the intermediate transfer belt 10. Thereafter, the photosensitive surface of the photosensitive drum 6 is cleaned by the drum cleaner 11, and the exposure-development-primary transfer process is completed.

In the case of full-color copying, when the first exposure-development-primary transfer process for yellow is completed, a green filter plate is
5G is selected and positioned on the optical path, the photosensitive surface of the photosensitive drum 6 is exposed by the reflected light of the original passing therethrough to form an electrostatic latent image, and a magenta developing device having a complementary color of green.
The magenta toner image is visualized at 9M and is superimposed on the yellow toner image on the intermediate transfer belt 10.

When the second exposure-development-primary transfer step is completed, a red filter plate 5R is selected in the third color separation filter unit 5 and positioned on the optical path, and the photosensitive drum is reflected by the original reflected light passing therethrough. The photosensitive surface of No. 6 is exposed to form an electrostatic latent image, visualized by a cyan developing device 9C which is a complementary color of red, and superimposed on the yellow and magenta toner images on the intermediate transfer belt 10 to form a cyan toner image. Is transferred to form a full-color toner image of yellow, magenta, and cyan.

During this primary transfer step, the belt cleaner 15 of the intermediate transfer belt 10 is turned off by the solenoid 28 being turned off.
Away from The drive roller 20 is also separated from the intermediate transfer belt 10 by turning on the solenoid 24.

On the other hand, the position of the intermediate transfer belt 10 is detected by the sensor 25, and at a predetermined timing according to the detection signal, the transfer paper is fed from the paper feed cassette 40 by the paper feed roller 40a and sent out to the registration roller 41. The transfer paper is sent out to the secondary transfer charger 13 at a predetermined timing by the registration roller 41, and a positive potential full-color toner image on the intermediate transfer belt 10 is statically transferred by the secondary transfer charger 13 to which the negative potential is applied. It is electrically attracted and secondarily transferred to transfer paper.

The transfer paper on which the toner image has been transferred is discharged by applying an AC potential by the charge removing charger 14, separated from the intermediate transfer belt 10, sucked and transferred by the transfer paper transfer belt 42, and sent to the heated fixing device 43. Then, the paper is discharged onto the paper discharge tray 44.

On the other hand, the intermediate transfer belt 10 after the secondary transfer is cleaned by the belt cleaner 15, and subsequently, 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 described in detail with reference to FIG. When the image leading end position passes through the secondary transfer position, before reaching the belt cleaner 15, the drive motor 21 is first driven to rotate the drive roller 20 at the same peripheral speed as the intermediate transfer belt 10, and then the solenoid 24
By turning off the intermediate transfer belt 10, 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 to press the belt cleaner 15 against the intermediate transfer belt 10. The upper residual toner is removed. At this time, a load acts on the intermediate transfer belt 10, but since the intermediate transfer belt 10 is securely driven between the belt cleaner roller 19 and the drive roller 20, the feeding unevenness due to slip of the intermediate transfer belt 10 or the like is caused. There is no occurrence of expansion or contraction of the intermediate transfer belt 10 or the like, and image shift and synchronization shift can be reliably prevented.

Next, after an appropriate time after the image rear end position has passed through the belt cleaner 15, the belt cleaner 15 is retracted in the reverse order to the above, the drive roller 20 is retracted, and then the drive motor 21 is stopped. Accordingly, the running of the intermediate transfer belt 10 is not affected even when the belt cleaner 15 is separated.

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

In the above embodiment, the example of the belt cleaner using the blade method is shown, but other cleaning methods such as a fur brush cleaner can be similarly configured. Further, the present invention can be applied not only to the cleaning of the intermediate transfer belt, but also to the cleaning of a photoconductor, a transfer paper support, and the like formed of an endless belt.

(Effect of the Invention) According to the image forming apparatus of the present invention, as is apparent from the above description, when the cleaning member is brought into contact with the endless belt, the driving roller is located at a position downstream of the contact position of the cleaning member before the contact. By driving the endless belt with the endless belt at a speed equal to the moving speed thereof and pressing the endless belt, it is possible to eliminate the influence of the load fluctuation of the endless belt due to the contact and separation of the cleaning member. An endless belt as an image carrier or a transfer material support can be cleaned without causing the occurrence of the synchronization or the synchronization shift.

[Brief description of the drawings]

1 to 5 show an embodiment in which the present invention is applied to a full-color copying machine. FIG. 1 is an overall schematic diagram, FIG. 2 is a perspective view around an intermediate transfer belt, and FIG. FIG. 4 is a perspective view of a filter unit, FIG. 4 is a block diagram showing a schematic configuration of a main part of a control unit, and FIG. 5 is a timing chart of an operation. 6 photoreceptor drum 10 intermediate transfer belt 15 belt cleaner 20 drive roller 21 drive motor 22 swing arm 23 tension spring 24 solenoid

Claims (1)

(57) [Claims] 1. An image comprising an image carrier or transfer paper support comprising an endless belt driven in rotation, and a cleaning member movable between a cleaning position in contact with the endless belt and a retracted position separated therefrom. In the forming apparatus, a position where a drive roller rotatable at a peripheral speed equal to the moving speed of the endless belt is pressed against the endless belt at a position downstream of the contact position of the cleaning member with the endless belt in the moving direction of the endless belt. Before the cleaning member is moved from the retracted position to the cleaning position and brought into contact with the endless belt, the precursor driving roller is moved at a speed equal to the moving speed of the endless belt. An image forming apparatus configured to be pressed against an endless belt while rotating at a peripheral speed.