JPH09211999A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in material and transferability by releasing an intermediate transfer member in press contact with an image forming body and a transfer member from them, when the device is not in use. SOLUTION: The device is constituted as follows; rollers 14A and 14B which stretch an intermediate transfer belt 14 are supported by supporting frames 114A and 114B energized toward the periphery of a photoreceptor drum 10 respectively, while a transfer roller 15 is supported by a supporting frame 115 energized toward the periphery of the intermediate transfer belt 14 and the rotational phases of respective eccentric cams 200 and 300 brought into contact with or separated from the supporting frames 114A and 114B and 115, in accordance with the use or unuse of the device are switched, so that the belt 14 is brought into press-contact with or separated from the photoreceptor drum 10 and the transfer roller 15 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly arranges a plurality of charging means, image exposing means and developing means on the peripheral surface of a drum-shaped image forming body to form a toner image during one rotation of the image forming body. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic color image forming apparatus that is formed by superimposing on a body.

[0002]

2. Description of the Related Art As a method of forming a multi-color image, image exposure and development of an image corresponding to each color are sequentially repeated during one rotation of an image forming body to superimpose toner images of each color on the image forming body. There is known a color image forming apparatus for forming a color image.

However, in such an apparatus, a plurality of charging means, image exposing means, and developing means are arranged on the peripheral surface of the image forming body, and furthermore, a space is also required in a transfer material conveying area and a cleaning means. Insufficient peripheral space,
Therefore, there are drawbacks that layout is difficult, a large-sized image forming body having a long peripheral surface is required, and the balance is poor.

As one method for solving this shortage of space, the base of the image forming body is made transparent, each image exposing means is housed inside the image forming body, and the image is exposed from the inside of the image forming body. An apparatus that sets the transport surface of the transfer material transported from the tangential direction to the transfer area by using the intermediate transfer material at a position away from the peripheral surface of the image forming body. Proposed.

[0005]

However, since the above-mentioned intermediate transfer material is directly pressed against the photosensitive surface of the image forming body in the transfer area of the image, the photosensitive characteristics of the image forming body during long-term use. When a belt is used as an intermediate transfer material, tension is constantly applied to the belt itself, so that the belt loses elasticity and the transfer efficiency is lowered.

Further, in the case of the above-mentioned intermediate transfer material, when an unexpected trouble such as a conveyance failure (jam) of the transfer material occurs, even if the image forming process is stopped, the toner image formation and the toner image transfer which have already been performed are continued. Then, there is a problem that unnecessary toner is scattered or adheres to a transfer roller which is used as a transfer unit to a transfer material and is in a pressed state.

On the other hand, however, the use of the intermediate transfer material
Since the degree of freedom in the layout of the transfer material transport path is increased, it is desired to realize a more multifunctional device that takes advantage of its advantages and has few troubles and easy processing.

As a result of solving these problems and improving the present invention, the transfer efficiency of a toner image is good, and there is no fear of toner adhesion or scattering due to toner scattering even when image formation is interrupted.
It is an object of the present invention to provide a color image forming apparatus using an intermediate transfer member that is compact and easy to maintain.

[0009]

The above object is to repeat charging, image exposure and development on an image forming body to form a toner image on the image forming body in a superimposed manner, and then form the toner image as an intermediate transfer member. In a color image forming apparatus that collectively transfers to a transfer material by a transfer unit including a transfer member, the intermediate transfer member is retracted away from the image forming body or the transfer member when the color image forming apparatus is not used. A color image forming apparatus (invention according to claim 1), which is placed at a position, and a toner image is formed on the image forming body by repeating charging, image exposure and development on the image forming body. Then, in a color image forming apparatus for collectively transferring the toner image onto a transfer material by a transfer unit including an intermediate transfer member and a transfer member, the operation of the color image forming apparatus is performed. At the time of stop, the intermediate transfer member is placed at a retracted position apart from the image forming body or the transfer member, and the image forming body is charged. , Image exposure and development are repeated to form a toner image on the image forming body in an overlapping manner, and then the toner image is transferred to an intermediate transfer member at a first transfer position and then transferred to a transfer member at a second transfer position. In a color image forming apparatus for transferring onto a transfer material, the image forming body is a drum-shaped image forming body,
A developing unit is arranged on the left and right of the drum-shaped image forming body, a cleaning unit is arranged below, and the intermediate transfer member is arranged on the upstream side of the rotation of the cleaning unit, and the second transfer position is located further upstream of the first transfer position. The transfer image storage unit, the sheet feeding unit, the second transfer position, and the fixing unit are arranged at substantially the same horizontal position by being located at the position (1). Invention).

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of each embodiment of the present invention, the configuration of a color image forming apparatus common to each invention will be described with reference to FIGS. 1 and 2.

Reference numeral 10 denotes a drum-shaped image forming body, that is, a photosensitive drum, which is coated with a transparent conductive layer and an organic photosensitive layer (OPC) on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. It was done.

A flange 10A at one end of the photosensitive drum 10 has a guide pin 30 provided in the cartridge 30.
The bearing 10 is supported by P, and the flange 10B at the other end
Is a plurality of guide rollers 40 provided on the substrate 40 of the apparatus body.
The outer peripheral gear 10G is fitted on the outer peripheral gear 10G to mesh with the drive gear 40G, and the power thereof is rotated clockwise while the transparent conductive layer is grounded.

Reference numeral 11 denotes a scorotron charger, which performs a charging operation on the above-mentioned organic photosensitive layer of the photosensitive drum 10 by a grid held at a predetermined potential and a corona discharge by a discharge wire, so that the photosensitive drum 10 is electrically charged. Such a potential is applied.

Reference numeral 12 is an exposure optical system composed of LEDs and SELFOC lenses arranged in the axial direction of the photosensitive drum 10, and image signals of respective colors read by a separate image reading device are sequentially taken out from the memory. And is input as an electric signal to each of the exposure optical systems 12 described above.

Each of the exposure optical systems 12 is mounted on a columnar support member 20 which is fixed to the substrate 40 of the apparatus main body using guide pins 40P1 as guides, and is housed inside the base of the photosensitive drum 10. .

Reference numerals 13Y to 13K denote developing units for accommodating yellow (Y), magenta (M), cyan (C) and K (black) developers, respectively, each having a predetermined gap with respect to the peripheral surface of the photosensitive drum 10. The developing sleeve 130 rotates in the same direction while maintaining the above.

Each of the developing units is brought into a non-contact state by applying a developing bias voltage to the electrostatic latent image formed on the photosensitive drum 10 by the charging by the charger 11 and the image exposure by the exposure optical system 12. To reverse development.

Next, the process of the color image forming apparatus in the present apparatus will be described.

The original image is temporarily stored in an image reading device, which is separate from the present device, as an image read by an image pickup device or an image edited by a computer as an image signal for each color of Y, M, C and K. Are stored and stored in.

When the image recording is started, the drive gear 40G is rotated by the start of the photoconductor drive motor to rotate the photoconductor drum 10 in the clockwise direction, and at the same time, the charger 11 is driven.
The application of the potential to the photosensitive drum 10 is started by the charging action of (Y).

After a potential is applied to the photosensitive drum 10, exposure by an electric signal corresponding to a first color signal, that is, an image signal of yellow (Y) is started in the exposure optical system 12 (Y), and the drum is exposed. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface by rotational scanning.

The latent image is reversely developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Exposure is performed by an electric signal corresponding to the magenta (M) image signal, and non-contact reversal development by the developing device 13 (M) causes a magenta (M) toner image on the yellow (Y) toner image. Will be sequentially stacked.

By the same process, the charger 11 (C),
The exposure optical system 12 (C) and the developing unit 13 (C) further form a cyan (C) toner image corresponding to the third color signal, and the charging unit 11 (K), the exposure optical system 12 (K) and the developing unit 13 (C). A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the unit 13 (K), and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10. You.

Photosensitive drum 1 using each of these exposure optical systems
The exposure of the organic photosensitive layer of No. 0 is performed from the inside of the drum through the above-mentioned transparent substrate. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image. In order to stabilize the temperature inside the photoconductor drum 10 and prevent the temperature rise due to the heat generation of each exposure optical system 12, a material having good thermal conductivity is used for the supporting member 20,
When the temperature is low, the heater 201 is used, and when the temperature is high, the heat is radiated to the outside through the heat pipe 202. Further, at the time of the developing action by each developing device, a developing bias to which a direct current or a further alternating current is applied is applied to the developing sleeve 130, and a jumping development is performed by a one-component or two-component developer contained in the developing device, so that the developing sleeve 130 is transparent. Non-contact reversal development is performed on the photosensitive drum 10 that grounds the conductive layer.

The color toner image thus formed on the peripheral surface of the photosensitive drum 10 is once transferred to the peripheral surface of the intermediate transfer belt 14 which is an intermediate transfer member.

The intermediate transfer belt 14 has a thickness of 100
～500Myuemu, electrical resistance is made of urethane rubber of 10 ⁸ ~10 ¹¹ Ω · cm, are those further provided with a teflon layer of 5~50μm having similar resistance to toner filming prevention on the surface layer, the roller 14A , 14B, 14C
And 14D, and is circulated counterclockwise in synchronization with the peripheral speed of the photoconductor drum 10 by the power transmitted to the roller 14D and conveyed.

Intermediate transfer belt 1 which is the above-mentioned intermediate transfer member.
Reference numeral 4 indicates that the belt surface between the rollers 14A and 14B is in contact with the peripheral surface of the photosensitive drum 10, while the outer peripheral belt surface of the roller 14C is in contact with the transfer roller 15 which is a transfer member, and the toner image is transferred at each contact. Forming a zone.

The color toner image adhered to the peripheral surface of the photosensitive drum 10 is first subjected to intermediate transfer sequentially by applying a bias voltage having a polarity opposite to that of the toner to the roller 14B at the contact point with the intermediate transfer belt 14. The image is transferred to the peripheral surface of the belt 14. That is, the color toner image on the drum is conveyed to the transfer area without scattering the toner by the guide of the roller 14A which is grounded, and is transferred to the roller 14B by 1
The transfer is efficiently performed on the intermediate transfer belt 14 side by applying a bias voltage of about 2 kV.

On the other hand, the paper feed roller 1 of the paper feed cassette 16
The transfer paper P is unloaded by the operation of 7 and fed to the timing roller 18, and is fed to the transfer area of the transfer roller 15 in synchronization with the conveyance of the color toner image on the intermediate transfer belt 14.

The transfer roller 15 is connected to the intermediate transfer belt 14.
The transfer sheet P, which is rotated clockwise in synchronism with the peripheral speed of the intermediate transfer belt P, is fed to the intermediate transfer belt in the transfer area formed by the nip portion between the transfer roller 15 and the roller 14C in the grounded state. The color toner images are sequentially transferred onto the transfer paper P by applying a bias voltage of 1 to 2 kV to the transfer roller 15 which is in close contact with the color toner images on the transfer roller 14 and has the opposite polarity to the toner.

The transfer paper P having the color toner image transferred thereto is discharged by the discharging needle 19A, is conveyed to the fixing device 21 via the conveying belt 19, and is sandwiched and conveyed between the heat roller 21A and the pressure roller 21B. Then, the toner is fused and fixed, and then discharged to the outside of the apparatus through the paper discharge roller 22.

Cleaning devices 100, 140 and 150 are installed on the photoconductor drum 10, the intermediate transfer belt 14 and the transfer roller 15, respectively, and the blades of the cleaning devices 100, 140 and 150 are constantly in pressure contact with each other to remove the residual adhered toner. The surface is always kept clean.

(Embodiment 1) Embodiments of the inventions according to claims 1 to 3 and claims 4 to 6 will be described with reference to FIGS. 3 and 4.

The rollers 14A and 14B acting to press the photosensitive drum 10 from the inside of the intermediate transfer belt 14 have their both axial ends in a direction substantially perpendicular to the peripheral surface of the photosensitive drum 10, as shown in the drawing. Is rotatably supported by support frames 114A and 114B that are guided and urged by the support frames 114A and 114B, and at the time of image formation, the eccentric cam 200 is separated by the support frames 114A and 114B as shown in FIG. 3A. The rollers 14A and 14B which are rotating are pressed against the peripheral surface of the photoconductor drum 10 in a state where tension is applied to the transfer belt 14 by the action of the spring member in the compressed state.

On the other hand, both ends of the transfer roller 15 are rotatably supported by a support frame 115 which is guided and biased from below with respect to the peripheral surface of the roller 14C as shown in the drawing, and is eccentric at the time of image formation. As shown in FIG. 3 (a), the cam 300 is rotated at an angle away from the support frame 115, and the transfer roller 15 sandwiches the transfer belt 14. It is pressed by the action of the compression spring.

The eccentric cams 200 and 300 have a shaft 200A, a shaft 30 and a rotary solenoid (not shown).
When the color image forming apparatus is not used, that is, when the image forming process is not performed or when the power of the apparatus is not input, the operation is stopped, that is, the power is input. However, when the image recording process is stopped due to a jam of the transfer sheet P, the solenoid is actuated and both are rotated halfway as shown in FIG. 3B.

Therefore, the support frames 114A and 114 described above are used.
B moves downward together to retract the rollers 14A and 14B away from the peripheral surface of the photosensitive drum 10, and at the same time, the support frame 115 also moves downward to move the transfer roller 15
Is separated from the peripheral surface of the intermediate transfer belt 14 and retracted.

As a result, the photosensitive drum 10, the intermediate transfer belt 14 and the transfer roller 15 are all released from the pressure contact with each other, so that the characteristics of transfer and photosensitivity are not changed, and the elasticity of the belt is prevented from being lowered, so that the belt is maintained for a long time. Can withstand the use of.

The intermediate transfer belt is integrated into the cartridge 400 together with the attached cleaning device 140,
If the apparatus is configured so as to be movable in the depth direction of the apparatus via the pair of left and right guide rails 400A, the apparatus is separated by separating the intermediate transfer belt 14 from the photosensitive drum and retracting the transfer roller 15 from the intermediate transfer belt 14. It becomes possible to easily attach / detach to / from the apparatus main body when not in use.

When a trouble such as a jam occurs or the operation of the apparatus is stopped such as a sudden image stop command, the cleaning units 100, 140 and 150 are operated for a predetermined time, respectively, and the photosensitive drum 10, the intermediate transfer belt 14 and The toner image on the transfer roller 15 or the adhered toner is cleaned and removed. Also at this time, the intermediate transfer belt can be easily attached to and detached from the apparatus main body.

FIG. 4 shows the intermediate transfer belt 14 with the transfer roller 1
5 shows another structural example in which the intermediate transfer belt 14 is separated from and retracted from the cartridge 5. The intermediate transfer belt 14 is housed in the cartridge 500 together with the cleaning device 140, and a cartridge is rotated by a rotary solenoid (not shown) via an integral rotary shaft 500A. The side surface of 500 is rotated within the range of the angle at which it comes into contact with the stop pins P1 and P2.

When the image forming apparatus is not used or when the operation is stopped, the rollers 14A and 14B have the eccentric cam 200 as in the previous example.
Is rotated to separate from the peripheral surface of the photosensitive drum 10 to reduce the tension of the intermediate transfer belt 14, and
00A is rotated in the clockwise direction to the position shown by the alternate long and short dash line in FIG.
4C is moved to separate the intermediate transfer belt 14 from the peripheral surface of the transfer roller 15 and retract it.

Therefore, the transfer roller 15 itself does not need to move, which simplifies the structure, and the cartridge 500 can be constructed so that it can be attached to and detached from the apparatus like the cartridge 400 in the previous example.

Also in this example, each cleaning device is operated when the device is stopped, as in the case of the previous example.

(Second Embodiment) An embodiment of the present invention according to claims 7 to 10 will be described with reference to FIGS.

The developing units are the developing units 13Y and 13M on the left-hand side peripheral surface of the photosensitive drum 10, and the developing unit 13 on the right-hand side peripheral surface.
C and 13K are sequentially arranged in the downstream direction of rotation of the drum so that they occupy substantially symmetrical positions.

Since each of the above-mentioned developing devices can be positioned so as to face the upper peripheral surface of the photosensitive drum 10, the lower peripheral surface of the drum is widely opened, so that the cleaning device 100 is located almost directly below. Further, the intermediate transfer belt 14 can be installed on the upstream side of the rotation.

Further, the toner image on the intermediate transfer belt 14 is transferred onto the transfer paper P at the first transfer position where the toner image on the photosensitive drum 10 is transferred to the intermediate transfer belt 14, that is, the pressure contact position with the drum surface of the roller 14B. As shown in FIG. 5, the second transfer position for transfer onto the transfer roller, that is, the position where the roller 14C is pressed against the transfer roller 15 is further upstream in the rotation direction of the drum.
A timing roller 18 for feeding paper synchronously,
The above-mentioned second transfer position, and the fixing device 2 as a fixing means.
1 and 1 can be arranged at substantially the same horizontal position, and as a result, the transfer distance of the transfer paper P is short and simple, the printing speed is increased, the transfer trouble is reduced, and the processing is facilitated.

It is also possible to stack a plurality of paper feed cassettes 16 vertically and feed the transfer paper P from any of the paper feed cassettes 16 from the above-mentioned horizontal position. The double-sided intermediate unit 600 is installed in the space below the transfer roller 15 and the fixing device 21 on the right side of the paper cassette group, and the transfer paper P on which one side of the image has been fixed is once inserted into the double-sided intermediate unit 600, and the reverse feeding is performed. It is also possible to configure so that images can be recorded on both front and back surfaces of the transfer paper P by performing the above.

Further, by arranging the transfer surface of the transfer paper P at the same horizontal position, the fixing device 21 is moved away from the photoconductor drum 10 and the developing device group, and the deterioration of the performance of the photoconductor due to heat generation is avoided, and the development performance is stabilized. To be done.

The transfer roller 15 and the fixing device 21 include a cleaning device 150, a charge eliminating needle 19A, a guide plate 19B, and a container 2 for releasing oil supplied to the fixing roller.
1C and a cartridge 700 as shown in FIG.
It can also be configured to be attached and detached via 00A.

In each of the embodiments, a color image forming apparatus is described in which the image exposure means is housed inside a transparent photosensitive drum, and image exposure is performed on the photosensitive drum on the outer periphery from the inside of the drum. However, according to the present invention, as shown in FIG. 7, exposure scanning for performing image exposure by dividing the optical path of the laser optical system by rotating the four light sources (not shown) and the polygon mirror PM into left and right in the figure, or an LED as shown in FIG. The present invention can also be applied to a color image forming apparatus in which image exposure is performed from the outside of the photoconductor drum 10 by exposure scanning of a line head optical system using a selfoc lens and the like. You can get it.

Further, the present invention can be applied to a color image forming apparatus using a roller-shaped intermediate transfer member as shown in FIG. 9 instead of the belt-shaped intermediate transfer member except for a part thereof. I can.

[0055]

According to the present invention, the intermediate transfer member is released from the pressure contact with the image forming body and the transfer member when the apparatus is not used or when the operation is stopped, so that the intermediate transfer member is kept in a free state. Deterioration of the photosensitive characteristics of the image forming body is prevented, and it is also possible to attach and detach the image forming body
It has become possible to provide a color image forming apparatus capable of always recording a high quality image by a stable image forming and transferring function.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus.

FIG. 2 is a sectional configuration diagram of a photosensitive drum.

FIG. 3 is a main part diagram of an apparatus showing a retracting type (I) of an intermediate transfer belt.

FIG. 4 is a main part diagram of an apparatus showing a retracting type (II) of an intermediate transfer belt.

FIG. 5 is a sectional view showing a layout example of an apparatus using an intermediate transfer belt.

FIG. 6 is a main part diagram of an apparatus using an intermediate transfer belt.

FIG. 7 is a main part diagram of a color image forming apparatus that performs image exposure with a laser optical system.

FIG. 8 is a sectional view of a color image forming apparatus that performs image exposure with a line head optical system.

FIG. 9 is a configuration diagram of a color image forming apparatus using an intermediate transfer roller.

[Explanation of symbols]

 10 Photoreceptor Drum 11 Charging Device 12 Exposure Optical System 13 Developing Device 14 Intermediate Transfer Belt 14 'Intermediate Transfer Roller 15 Transfer Roller 16 Paper Feed Cassette 20 Supporting Member 21 Fixing Device 100, 140, 150 Cleaning Device 200, 300 Eccentric Cam 114A, 114B, 115 Support frame 400, 500, 700 Cartridge 400A, 700A Guide rail 500A Rotating shaft 600 Double-sided intermediate unit 600A Guide plate 600B Forward / reverse roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayasu Onodera, 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor ▲ Hama ▼ Tata Ta, 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company ( 72) Inventor Toshihide Miura 5-14-14-14 Midoricho, Koganei-shi, Tokyo

Claims (10)

[Claims] 1. A toner image is transferred from an intermediate transfer member and a transfer member after the toner image is formed on the image forming body by repeating charging, image exposure and development on the image forming body. In a color image forming apparatus for collectively transferring to a transfer material by means, when the color image forming apparatus is not in use, the intermediate transfer member is placed at a retracted position apart from the image forming body or the transfer member. Color image forming apparatus. 2. An image forming body is repeatedly charged, image exposed and developed to form a toner image on the image forming body in a superimposed manner, and then the toner image is transferred from an intermediate transfer member and a transfer member. In a color image forming apparatus for collectively transferring to a transfer material by means, the intermediate transfer member is placed at a retracted position apart from the image forming body or the transfer member when the operation of the color image forming apparatus is stopped. Color image forming apparatus. 3. The color image forming apparatus according to claim 1, wherein the intermediate transfer member is cleaned at the retracted position. 4. The intermediate transfer member is placed in the retracted position when a jam of the transfer material occurs.
Or the color image forming apparatus described in 2. 5. The color image forming apparatus according to claim 1, wherein the intermediate transfer member is attachable to and detachable from the apparatus main body at the retracted position. 6. The color image forming apparatus according to claim 1, wherein the intermediate transfer member is composed of a belt member, and the tension is reduced at the retracted position. 7. An image forming body is repeatedly charged, image exposed and developed to form a toner image on the image forming body in a superimposed manner, and then the toner image is transferred to an intermediate transfer member at a first transfer position. In a color image forming apparatus that transfers to a transfer material by a transfer member at a second transfer position, the image forming body is a drum-shaped image forming body, a developing unit is provided on the left and right sides of the drum-shaped image forming body, and cleaning is performed below. means,
By disposing the intermediate transfer member on the upstream side of rotation of the cleaning means and by arranging the second transfer position further upstream of the first transfer position, the transfer material storage portion, the paper feeding means, and the transfer means are provided. A color image forming apparatus characterized in that a second transfer position and a fixing unit are arranged at substantially the same horizontal position. 8. The transfer member and the fixing unit can be integrally attached to and detached from the apparatus main body.
The color image forming apparatus as described in the above. 9. The color image forming apparatus according to claim 7, wherein the transfer material storage portion can be installed below the horizontal position. 10. The color image forming apparatus according to claim 7, wherein the transfer member and the fixing unit allow a duplex unit of a transfer material to be disposed below.