JPH01166069A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce the scratch and the electric fatigue of a photosensitive body and an intermediate transfer body by making the intermediate transfer body press against the photosensitive body and making the intermediate transfer body separate from a cleaning device so that it is in a non-action state in case of primary transfer, and making the intermediate transfer body separate from the photosensitive body on the contrary in case of secondary transfer. CONSTITUTION:The intermediate transfer belt 10 is stretched by pressing rolls 17 and 18 on both sides of a primary transfer charger 12, a secondary transfer roll 19 and a cleaner pressing roll 20. One pressing roll 18 and the cleaner pressing roll 20 are supported on both end parts of rocking lever 22 supported freely rockingly with a pivoting shaft 21. And in case of the primary transfer, the intermediate transfer body is pressed against the photosensitive body and separated from the cleaning device to be in the non-action state. In case of the secondary transfer, the intermediate transfer body is separated from the photosensitive body on the contrary. Thus, the scratch and the electric fatigue of the photosensitive body and the intermediate transfer body can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that transfers images of each color from a photoreceptor onto an intermediate transfer member to form a multicolor image, which is then transferred at once. The present invention relates to an image forming apparatus that performs image transfer onto a transfer material.

(Prior Art) For example, Japanese Patent Application Laid-Open No. 56-147166 discloses 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 material. A device has been disclosed in which a cleaning device for the intermediate transfer member is rendered inoperative when multiple transfer is performed on the intermediate transfer member. However, the intermediate transfer member and the photoreceptor are always in pressure contact with each other and cannot be separated from each other.

(Problem to be Solved by the Invention) However, in the image forming apparatus described above, the photoreceptor and the intermediate transfer member are in constant pressure contact, so even when only one needs to be driven, if one is stopped, scratches may occur. Therefore, it is necessary to drive both, and even if both are driven, physical damage will occur due to contact, and frictional electrification and peeling discharge will occur repeatedly due to repeated contact and separation at the contact area between the two. , there are problems such as causing electrical fatigue, and furthermore, a separate drive means is required to move the intermediate transfer member into contact with and away from the photoreceptor, which causes problems in terms of space and cost. There is.

In view of the above-mentioned conventional problems, the present invention provides an image processing system in which the pressing and separating operations between the photoreceptor and the intermediate transfer member and the pressing and separating operations between the intermediate transfer member and the cleaning device can be performed in conjunction with each other by a single driving means. The purpose is to provide a forming device.

(Means for Solving the Problems) In order to achieve the above object, the present invention electrostatically transfers a developed image obtained by developing an electrostatic latent image formed on a photoreceptor to an intermediate transfer member. This step is performed for each color to electrostatically retransfer the multiple color images formed on the intermediate transfer body onto the transfer material at once, and then the residual toner on the intermediate transfer body is removed by a cleaning device. In the image forming apparatus, the intermediate transfer member is moved between a first position where the intermediate transfer body is in pressure contact with the photoconductor and separated from the cleaning device, and a second position where it is separated from the photoconductor and in pressure contact with the cleaning device. It is characterized in that it is provided with a position switching means for moving.

In a preferred embodiment, the intermediate transfer member includes a pressure roller that presses the intermediate transfer member against the photoreceptor, and an intermediate transfer belt wound around a cleaner pressure roller that presses the intermediate transfer member against a cleaning device. The position switching means consists of:
It consists of a swing lever with the pressure roller and the cleaner pressure roller attached to both ends.

(Function) Since the present invention has the above-mentioned configuration, - during the next transfer, the intermediate transfer body is brought into pressure contact with the photoreceptor, and the intermediate transfer body is separated from the cleaning device to be in an inoperable state; By separating the transfer body from the photoconductor, damage to the photoconductor and intermediate transfer body and electrical fatigue can be reduced, and residual toner on the intermediate transfer body can be removed by pressing the intermediate transfer body against a cleaning device. I can do it,
Furthermore, by linking both operations, only a single driving means is required, which is advantageous in terms of space and cost.

In addition, by using an intermediate transfer belt as the intermediate transfer body and switching the position of the intermediate transfer body by swinging a swing lever, the position of the intermediate transfer body can be changed by moving the intermediate transfer belt to the secondary transfer section. Not only does this have no effect, but the tension of the intermediate transfer belt can be kept constant during both operations, making it possible to obtain stable images without expansion or contraction.

(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 3.

In FIG. 1, reference numeral 1 denotes an original platen glass on which an original is placed. Below the original platen glass 1, an exposure lamp 2,
An optical system consisting of first to fifth mirrors 3a to 3e, a lens 4, and a color separation filter unit 5 is provided. As shown in FIG. 2, in the color separation filter unit 5, a blue filter plate 5B, a green filter plate 5G, and a mixed filter plate 5R are supported by a frame 51 in parallel, and a drive motor 52, 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 90 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 dielectric material having good environmental resistance and dimensional stability, for example, an unfinished belt such as a polyimide film having a thickness of 50 to 100 μm and 8 degrees.

Around the intermediate transfer belt 10, a primary transfer charger 12 for transferring an image from the photosensitive drum 6 to the intermediate transfer belt 10, a secondary transfer pretreatment charger 13a113b,
A secondary transfer charger 14 for transferring an image from the intermediate transfer belt 10 to a transfer material, a static elimination charger 15, a belt cleaner 16, and the like are provided.

Further, as shown in detail in FIG.
．． 18, the secondary transfer row 219, and the cleaner pressure contact roller 2
It is stretched by four straight rollers. The one pressure roller 18 and the cleaner pressure roller 20 are
It is attached to both ends of a swing blue 22 whose intermediate portion is swingably supported by a pivot shaft 21. By swinging the swinging lever 22 with the slide/id 23, the intermediate transfer belt 10 is pressed against the photosensitive drum 6 by the pressure rollers 17 and 18, and the cleaner pressure roller 20 is moved to clean the belt cleaner 16. The intermediate transfer belt 10 is moved to a first position where it is separated from the blade 16a, and the intermediate transfer belt 10 is moved away from the photoreceptor drum 6 by the movement of the pressure roller 218, and the intermediate transfer belt 10 is pressed against the cleaning blade 16a by the cleaner pressure roller 20. The intermediate transfer belt 10 is configured to switch the position between the intermediate transfer belt 10 and the second position.

24 is a paper feed cassette, 25 is a registration roller, 26 is a transfer paper conveyance belt, and 27 is a fixing device including a fixing roller with a built-in heater.

Next, to explain the operation, a document placed on the document table lath 1 is sequentially scanned in the horizontal direction, and the reflected light is transmitted to the first to third mirrors 3a to 3c and the 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. After the photosensitive drum 6 is 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, the blue filter plate 5B
is located in the optical path, the yellow developing device 9Y, which is a complementary color to blue, is selected, and the developer on the developing sleeve is scraped off by the ear-cutting shutter at the rear of each developing sleeve in the other developing devices 9M and 9C. After that, 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 bell) 10 is driven in synchronization with the photoreceptor drum 6 at the same speed as 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 . Thereafter, 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 5G is selected in the color separation filter unit 5 and positioned on the optical path. The photosensitive surface of the photosensitive drum 6 is exposed to the reflected light of the original that has passed through, and an electrostatic latent image is formed.
The magenta toner image is transferred onto the yellow toner image on the intermediate transfer belt 10 in a superimposed manner.

When the second exposure-development and primary transfer process is completed,
For the third time, the color separation filter unit 5) red filter plate 5R is selected and placed 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 solenoid 23 is turned on and the swing lever 22 moves as shown by the solid line in FIGS. 1 and 3.
By swinging clockwise, the intermediate transfer belt 10
is pressed against the photosensitive drum 6 by the pressure roller 18, and the cleaner pressure roller 20 is separated from the cleaning blade 16a of the belt cleaner 16, so that the toner image transferred onto the intermediate transfer belt 10 is not erased. .

Next, when the -next transfer step is completed, the solenoid 23 is turned off and the swinging lever 22 is swung counterclockwise by a biasing means (not shown), as shown by broken lines in FIGS. 1 and 3. As a result, the pressure roller 18 moves to separate the intermediate transfer belt 10 from the photosensitive drum 6, and the cleaner pressure roller 20 comes into pressure contact with the cleaning blade 16a of the belt cleaner 16 via the intermediate transfer belt 10.

In this way, by bringing the intermediate transfer belt 10 into pressure contact with the photoreceptor drum 6 only in the -next transfer process and separating it at other times, the photoreceptor 6 can be stopped when the -next transfer is completed. In addition, the photoreceptor 6 and the intermediate transfer belt 10
During this time, there will be no scratches or electrical fatigue caused by repeated frictional charging and peeling discharge.

Next, the full-color toner image on the intermediate transfer belt 10 is pre-charged by secondary transfer pre-treatment chargers 13a and 13b. That is, the same positive potential as that of the toner image is applied to the pretreatment charger 13a on the front side of the intermediate transfer belt 10, and the opposite negative potential is applied to the pretreatment charger 13b on the back side, so that the charged state of the toner image is changed. The toner image is intensified prior to the next transfer, and then moved to the secondary transfer charger 14.

On the other hand, at a predetermined timing based on a signal from a position detection device (not shown) of the intermediate transfer belt 10, the transfer paper is fed out from the paper feed cassette 24 by the paper feed roller 24a and sent to the reno roller 25, and the transfer paper is fed by the registration roller 25. The transfer paper is sent to the secondary transfer charger 14 at a predetermined timing, and the full-color toner image with a positive potential on the intermediate transfer belt 10 is electrostatically attracted by the secondary transfer charger 14 to which a negative potential is applied, and transferred. transferred to paper.

An alternating current potential is applied to the transfer paper on which the toner image has been transferred, and the electricity is removed by the electricity removal charter 15.
The paper is separated, transported by suction by the transfer paper transport belt 26, and sent to a heated fixing device 27, where it is fixed and polished.

On the other hand, residual toner on the intermediate transfer belt 10 after the secondary transfer is cleaned because the intermediate transfer belt 10 is pressed against the cleaning blade 16a by the cleaner pressure roller 20 as described above.

Photosensitive drum 6 and intermediate transfer belt 1 in the above steps
0 and the operating states of the solenoid 23 are shown in FIG.

As described above, by strengthening the charging state of the first toner image prior to the secondary transfer using the pre-treatment chargers 13a and 131, the charge of the toner image transferred in the first and second primary transfer steps is reduced. Even if it is subtracted during the second or third primary transfer, it is especially a single color that is a toner image formed during the first primary transfer and no toner image is formed on top of it during the second or third primary transfer. Even in portions where the charge is likely to decrease due to the second and subsequent primary transfers, sufficient charge is retained by being charged again, and the toner image is efficiently and stably transferred.

In the above description, the photoreceptor drum 6, the next transfer charger 12, the back side pretreatment charge 13b, and the next transfer charger 14 are negatively charged, and the toner and the front side pretreatment charger 3a are positively charged. Although an example has been described, charging may be performed in the opposite manner.

In addition, in the above description, three primary transfers are performed on the intermediate transfer belt 10.
Although an example has been shown in which a full-color toner image is formed by rotating the toner image and transferred to a transfer paper, it goes without saying that a mode in which a monochromatic color image is formed and transferred may also be provided. In that case, the pretreatment chamber may or may not be activated.

Further, although the intermediate transfer belt 10 is used as an example of the intermediate transfer member in the above embodiment, an intermediate transfer drum may also be used.

(Effects of the Invention) According to the image forming apparatus of the present invention, as described above, the intermediate transfer member is brought into pressure contact with the photoreceptor during the primary transfer, and the intermediate transfer member is separated from the cleaning device to be in an inoperable state. During the next transfer, conversely, by separating the intermediate transfer body from the photoconductor, damage to the photoconductor and intermediate transfer body and electrical fatigue are reduced, and at the same time, the intermediate transfer body is brought into pressure contact with a cleaning device to clean the surface of the intermediate transfer body. It is possible to remove residual toner, and by linking both operations, it is possible to remove residual toner.
ll- driving means is sufficient, and it is possible to save space and reduce costs.

In addition, if an intermediate transfer belt is used as the intermediate transfer body and the position of the intermediate transfer body is changed by swinging a swing lever, the secondary transfer section will not be affected due to the position switching of the intermediate transfer body. Not only is the tension of the intermediate transfer belt constant during both operations, it is possible to obtain a stable image without expansion or contraction, which is a great effect.

[Brief explanation of the drawing]

1 to 4 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 a color selection filter unit, and FIG. 3 is an intermediate transfer FIG. 4, a perspective view of the belt and its surroundings, is a diagram showing the operation timing of each part.

Claims (2)

[Claims] (1) The process of electrostatically transferring the developed image obtained by developing the electrostatic latent image formed on the photoreceptor to the intermediate transfer member is performed for each of multiple colors, and the image is formed on the intermediate transfer member. In an image forming apparatus that electrostatically retransfers multiple color images onto a transfer material at once, and then uses a cleaning device to remove residual toner on the intermediate transfer member, the intermediate transfer member is transferred to a photoreceptor. An image forming apparatus comprising a position switching means for moving the image forming apparatus between a first position in which the photoreceptor is in pressure contact and is separated from the cleaning device, and a second position in which the photoconductor is in pressure contact and is in pressure contact with the cleaning device. (2) The intermediate transfer body consists of a pressure roller that presses the intermediate transfer body against the photoreceptor, and an intermediate transfer belt that is wound around a cleaner pressure roller that presses the intermediate transfer body against a cleaning device. 2. The image forming apparatus according to claim 1, wherein the means comprises a swing lever having the pressure roller and the cleaner pressure roller attached to both ends thereof.