JPH1195573A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a cleaning blade of an intermediate transfer body from being turned up even when many sheets of images are formed by actuating a blade turning up preventing means when the count number with a counting means reaches a fixed sheet number. SOLUTION: When the number of image forming sheets reaches a fixed value by the cumulative counting of the number of the image forming sheets, a control part SC outputs a signal to a toner image forming unit PU, to execute the process of supplying toner to the intermediate transfer body by the toner image forming unit PU. The toner after being supplied to the intermediate transfer body is scraped by the cleaning blade CB and then, acts as a lubricant for reducing the friction between the intermediate transfer body and the cleaning blade CB, so that the cleaning blade can be prevented from being turned up. Thus, when the images are consecutively formed in a surface image forming mode, the toner is supplied to the intermediate transfer body to reduce the friction between the intermediate transfer body and the cleaning blade CB and prevent the turning up of the blade.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus suitable for forming images on both sides of a transfer material by electrophotography. The image forming apparatus according to the present invention can be used for a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art Conventionally, in double-sided image formation, an image on one side formed on an image forming body is transferred and fixed on a transfer material, and is temporarily stored in a reversal feeding device and formed again. A method has been adopted in which a transfer material is fed from the reversing feeding device in synchronization with an image formed on the body, and the image is transferred and fixed to the other surface on the transfer material.

In this double-sided image forming apparatus, as described above, the transfer of the transfer material, such as feeding the fixed transfer material to the reversing feeder and passing the fixing device twice, is performed. Was unreliable, causing jams. In order to improve such a defect, an image is formed by forming a first image on a photoreceptor and then temporarily transferring the image on an intermediate transfer member as disclosed in Japanese Patent Publication No. 49-37538. Is formed on a photoreceptor, the first image on the intermediate transfer member and the second image on the photoreceptor are respectively transferred to both sides of the transfer material, and the first and second images on the transfer material are transferred. At the same time, a double-sided image forming apparatus has been proposed in which an image is formed on both sides of a transfer material by being fixed on the transfer material. The present inventor has conducted research on the practical use of this double-sided image forming method, and has filed Japanese Patent Application No. 8-7031.
He has filed numerous patent applications, including No. 7.

[0004]

A feature of the above-described image forming method using an intermediate transfer member is that a two-sided image is formed using the intermediate transfer member. In this image forming apparatus, both sides of a transfer material are used. In addition to the two-sided image forming mode for forming an image on the transfer material, a mode for forming an image only on the front surface of the transfer material and a mode for forming an image only on the back surface of the transfer material can be adopted.

[0005] In the two-sided image forming mode and the backside image forming mode among the above three image forming modes, the toner image on the transfer material is transferred from the image forming body to the intermediate transferring body and then transferred from the intermediate transferring body. The toner image is formed through a process of transferring to a transfer material, and a toner image is formed on the intermediate transfer body every time an image is formed.
Since the toner image is directly transferred from the image forming body to the transfer material without passing through the intermediate transfer body, the toner image is not formed on the intermediate transfer body in the surface image forming mode. As described above, in the surface image forming mode, there is no step of attaching the toner to the intermediate transfer body in the image forming process.

In the image forming method using the intermediate transfer member, it is essential to clean the intermediate transfer member, and the cleaning means for cleaning the intermediate transfer member is made of an elastic material such as urethane rubber. Cleaning blades are preferred. When an image forming process for forming an image without adhering toner to the intermediate transfer member is continued for a long time as in the surface image formation mode, friction between the cleaning blade and the intermediate transfer member increases, and the blade is turned up. Phenomenon occurs. This phenomenon is an undesired phenomenon that results in poor cleaning and impedes circulation movement of the intermediate transfer member.

Accordingly, the present invention solves the above-mentioned problem in an image forming apparatus having an intermediate transfer member, and forms a large number of images in a mode of forming an image without forming a toner image on the intermediate transfer member. Another object of the present invention is to provide an image forming apparatus which does not cause the turning of the cleaning blade of the intermediate transfer body cleaning apparatus.

[0008]

The object of the present invention is as follows.
A first mode in which a toner image formed on an image forming body is once transferred to an intermediate transfer body and then transferred from the intermediate transfer body to a transfer material to form an image on the transfer material, and a toner image formed on the image forming body A second mode in which an image is transferred from the image forming body to a transfer material without transferring the image to the intermediate transfer body to form an image on the transfer material. Counting means for counting the number of sheets, and blade turning-over preventing means for preventing turning of the cleaning blade of the intermediate transfer body cleaning device for cleaning the intermediate transfer body, when the count number by the counting means reaches a predetermined number The image forming apparatus is characterized in that the blade turning-up preventing means is operated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mechanical configuration of a double-sided image forming apparatus according to an embodiment of the present invention is as shown in FIG.

First, a double-sided image forming mode for forming images on both sides of a transfer material will be described. Photoconductor drum 10 used in the embodiment as a specific example of an image forming body
For example, a conductive layer and amorphous silicon, a photosensitive layer such as an organic photoconductive layer is sequentially formed on the outer periphery of a cylindrical base made of a transparent substance made of optical glass or transparent acrylic resin, and the conductive layer is It is rotated clockwise as indicated by the arrow when it is grounded.

The intermediate transfer member 14a has a thickness of 0.5 to 2.0 m.
m, a 5-50 μm thick fluororesin coating as a toner filming prevention layer on the outside of a semiconductive rubber substrate of silicon rubber or urethane rubber having a resistance of 10 ¹⁰ -10 ¹⁵ Ωcm. The two-layer structure is preferred. The coating layer is also preferably semiconductive. 0.1-thick instead of rubber substrate
0.5 mm semi-conductive polyester, polyethylene,
Resin substrates such as polyethylene terephthalate, polyimide, and ethylene tetrafluoroethylene can be used.

The chargers 11Y, 11M, 11C and 11K are scorotron chargers having discharge electrodes and grids, and the exposure units 12Y, 12M, 12C and 12K are light emitting elements LE.
D and an array of selfoc lenses, which are imaging elements, arranged in the rotation direction of the photosensitive drum. The developing units 13Y, 13M, 13C, and 13K are provided with the sleeve 131.
Is a developing device that performs non-contact reversal development by applying an AC bias in which a DC is superimposed on the DC. As the developer, a two-component developer is used, but a one-component developer can also be used.

Reference characters Y, M, C, and K represent the colors of the toner image formed at each stage. For example, 12Y is an exposure device for forming a yellow toner image, and forms a yellow image. It emits light when driven by an image signal.

When the image formation is started, the photosensitive drum 10 rotates clockwise as indicated by an arrow. First, the photosensitive drum 10 is uniformly charged by a scorotron charger 11Y, and an image of a yellow image is exposed by an exposure unit 12Y. Exposure is performed, and an electrostatic latent image is formed on the photosensitive drum 10. This electrostatic latent image is developed by the developing device 13Y to form a yellow toner image. By the subsequent rotation of the photoconductor drum 10, by the charging by the scorotron charger 11M, the exposure by the exposure unit 12M, and the development by the developing unit 13M,
A magenta toner image is formed, and a scorotron charger 11 is formed.
Charging by C, exposure by a scorotron exposure unit 12C,
A cyan toner image is formed by development by the developing device 13C, and charging by the scorotron charger 11K,
A black toner image is formed by exposure to 2K and development by the developing device 13K. By superimposing these primary color toner images, a back color toner image is formed on the photosensitive drum 10.

With the subsequent rotation of the photosensitive drum 10, the transfer area 1
In 4b, the photosensitive drum 10 comes into contact with the intermediate transfer member 14a, and the color toner image on the back surface of the photosensitive drum 10 is transferred to the intermediate transfer member 14a by the transfer operation of the primary transfer device 14c. The primary transfer device 14c forms a transfer electric field in the transfer area 14b by charging the surface of the intermediate transfer member 14a opposite to the surface facing the photoreceptor drum 10 with a polarity opposite to that of the toner. This increases the transfer rate.

After the transfer, the AC static eliminator 16, the photosensitive drum cleaning device 19, and the uniform exposure device 12e operate.
The surface of the photosensitive drum 10 is cleaned, and the process for forming the next color toner image is started.

After the formation of the back color toner image, the photosensitive drum 10 is further rotated, and the yellow, magenta, cyan and black primary color toner images are superimposed on the photosensitive drum 10 by the same image forming process as described above. The formed surface color toner image is formed. This surface color toner image is formed on the photosensitive drum 10 as an image obtained by performing a mirror image process on the original image, that is, a left-right inversion process. This is because, as will be described later, as a result of forming the back color toner image on the transfer material by performing the transfer twice, the image is horizontally inverted twice, resulting in a relationship between the original image and the normal image. This is because the surface color toner image is formed on the transfer material by one transfer, and thus has a relationship between the original image and a mirror image that is inverted left and right.

In synchronization with the formation of the front surface color toner image, the transfer material P is sent out from the paper feed cassette 15 by the feed roller 15a and is conveyed to the timing roller 15b. The timing roller 15b operates in synchronization with the formation of the front surface color toner image, and conveys the transfer material P to the transfer area 14b. The transfer material P is charged to the same polarity as the toner by the transfer material charger 14f and is attracted to the intermediate transfer body 14a. The reason that the transfer material P is charged to the same polarity as the toner is to prevent the toner from being attracted by the charging and disturbing the image.

The surface color toner image on the photosensitive drum 10 is transferred to the surface (upper surface) of the transfer material P in the transfer area 14b by the transfer operation of the primary transfer device 14c. At the time of transfer, the transfer rate is increased by the transfer simultaneous exposure device 12d.

After the transfer of the surface color toner image to the transfer material P, the transfer material P and the intermediate transfer member 14a are transferred to the secondary transfer device 14a.
g, and the back color toner image on the intermediate transfer member 14a is transferred to the back surface (lower surface) of the transfer material P by the charging of the secondary transfer device 14g having the polarity opposite to that of the toner. The transfer material P having the color toner images formed on both sides in this way is separated by the AC neutralizer 14h as the transfer material separating means and the separating claw 20 as the transfer material separating auxiliary means, and further, the curvature separation by the driving roller 14d. The transfer material P, which is separated from the intermediate transfer body 14a by operation and carries an unfixed toner image on both surfaces, is guided by a spur 21 as transfer material guide means and is conveyed to the fixing device 17. In the fixing device 17, heat and pressure are applied between an upper roller 17a, which is an upper heating member having a heat source therein, and a lower roller 17b, which is a lower heating member, so that the color toner image is fixed. An image is formed.

After fixing the color toner image, the intermediate transfer member 14
a remaining toner on the intermediate transfer member cleaning device 14
The cleaning is performed by bringing the cleaning blade i into contact with the intermediate transfer member 14a. The toner remaining on the photosensitive drum 10 after the transfer is the photosensitive drum AC
After the charge is removed by the charge remover 16, the toner is scraped into the photosensitive drum cleaning device 19 by the cleaning blade 19 a of the photosensitive drum cleaning device 19, and is collected by a screw 19 b in a toner container (not shown).

Next, a process in a surface image forming mode for forming an image only on the surface of the transfer material will be described.

A color toner image is formed on the photosensitive drum 10 through the same image forming process as described above. The timing roller 1 is synchronized with the formation of the color toner image.
5b operates to transfer the transfer material P to the transfer area 14b. After the color toner image on the photosensitive drum 10 is transferred to the surface (upper surface) of the transfer material by the primary transfer device 14c,
The transfer material P is conveyed by the intermediate transfer body 14a and introduced into the fixing device 17, where fixing is performed, and an image is formed only on the surface of the transfer material P. As described above, in the surface image forming mode, the toner image is directly transferred to the transfer material P, and the intermediate transfer body 14a has only a function of transporting the transfer material.

Next, a process in a backside image forming mode for forming an image on only the backside of the transfer material will be described.

A color toner image is formed on the photosensitive drum 10 through a process similar to that described for forming a double-sided image. This color toner image is transferred to the intermediate transfer member 14a by the primary transfer device 14c in the transfer area 14b. After the transfer, the toner image is not formed on the photosensitive drum 10 and the rotation of the photosensitive drum 10 and the circulation of the intermediate transfer member 14a are continued, and the toner image is supplied in synchronization with the color toner image on the intermediate transfer member 14a. The color toner image is transferred from the intermediate transfer member 14a to the back surface (lower surface) of the transfer material P by the secondary transfer device 14g on the transfer material P, and is fixed by the fixing device 17, and the image is formed only on the back surface of the transfer material P. Is formed.

An embodiment according to the main part of the present invention will be described below.

FIG. 2 is a block diagram showing a control system of the double-sided image forming apparatus according to the first embodiment.

MS1, MS2, and MS3 are mode selection buttons. MS1 selects the above-described double-sided image forming mode.
S2 is a button for selecting the above-described front side image forming mode, and MS3 is a button for selecting the above-mentioned back side image forming mode. PC
Is a counter for counting the number of formed images. PU
Is a toner image forming unit composed of the charger 11, the exposure unit 12 and the developing unit 13, and CB is an intermediate transfer member 14a.
SC is a control unit.

In the double-sided image forming mode, the toner image is transferred from the photosensitive drum 10 to the intermediate transfer member 14a and then transferred from the intermediate transfer member 14a to the back surface of the transfer material P to form a back toner image. The toner is directly transferred from the drum 10 to the surface of the transfer material P to form a surface toner image.

In the surface image forming mode, the intermediate transfer member 14 is directly transferred from the photosensitive drum 10 to the transfer material P to form a surface toner image on the surface of the transfer material P.
No toner image is formed with a.

In the backside image forming mode, after the toner image is transferred from the photosensitive drum 10 to the intermediate transfer member 14a, the toner image is transferred from the intermediate transfer member 14a to the back surface of the transfer material.
A toner image is formed on the surface of the transfer material P.

In the control section SC, the toner image formation with the intermediate transfer member 14a interposed by the image formation mode selection button MS2 according to the input from the image formation mode selection buttons MS1, MS2 and MS3 and the number of image formation from the counter PC. The number of image formations in which the surface image formation mode in which the image formation is not performed and the image formation is continuously performed is cumulatively counted. That is, when the image forming mode is changed, the count is initialized in the cumulative number of continuous image forming sheets in the front image forming mode. Further, even if the image forming operation is interrupted in the middle, this cumulative counting is continued. Therefore, for example, when the image formation in the front side image formation mode is performed and the mode is changed to the double-sided image formation after performing 50 sheets, the double-sided image formation is performed.
The count of sheets is initialized to zero. On the other hand, after the image formation of 50 sheets is performed in the front surface image formation mode, even if the image formation is interrupted, the image formation in the front surface image formation mode is performed again without being changed to another mode. , The number of image formed after the interruption of 50 sheets is added to 50 sheets.

By the above-described cumulative counting of the number of image formation sheets, when the number of image formation sheets reaches the predetermined value N1, the control unit SC outputs a signal to the toner image formation unit PU, and the control unit SC outputs the signal to the next. A process of applying toner to the intermediate transfer member 14a as described in (1) is executed.

The predetermined value N1 at which the controller SC outputs a signal to the toner image forming unit PU to execute the toner application process is determined by various performances and characteristics of the image forming apparatus. For example, the predetermined number N1 is determined according to the number of images formed per minute, the surface properties of the intermediate transfer body 14a, the material of the cleaning blade CB, the properties of the toner, and the like. As the predetermined value N1, a value in the range of 100 to 1000 is usually selected,
It is not limited to this value.

The method of applying the toner to the intermediate transfer member 14 a is appropriately selected. For example, after a fixed potential is formed on the surface of the photosensitive drum 10 by the scorotron charger 11, the intermediate device is exposed by the exposure device 12. Is performed, and the developing unit 13 reversely develops the toner image to form a toner image having a width of several millimeters on the photosensitive drum 10 over the entire length of the photosensitive drum 10 in the rotation axis direction. A method of transferring to the intermediate transfer body 14a by the transfer device 14c is adopted.

After the toner supplied to the intermediate transfer member 14a is scraped off by the cleaning blade CB, it acts as a slipping agent to reduce the friction between the intermediate transfer member 14a and the cleaning blade CB. Is done. By supplying toner to the intermediate transfer member when continuous image formation is performed in the surface image formation mode, friction between the intermediate transfer member 14a and the cleaning blade CB is reduced, and blade turning is prevented. Is done.

(Second Embodiment) FIG. 3 is a block diagram of a control system of an image forming apparatus according to a second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals.

Reference numeral SD denotes a solenoid which is a blade driving means for bringing the cleaning blade CB into contact with and separating from the intermediate transfer member 14a. HV1 and HV2 are high-voltage power supplies for the primary transfer device 14c and the secondary transfer device 14g, respectively.

As in the first embodiment, when the cumulative count in the front surface image forming mode reaches a predetermined value N2, the control unit SC
, The solenoid SD operates to move the cleaning blade CB away from the intermediate transfer member 14a. This prevents the cleaning blade from turning up. The predetermined value N2 in this embodiment is set in consideration of various conditions similarly to the above-described predetermined value N1, and 100 to
The value is set to about 1000. As in the first embodiment, the present invention is not limited to this value. If image formation is continued for a long period of time with the cleaning blade CB separated from the intermediate transfer member 14a, dirt such as toner and paper dust adheres to the intermediate transfer member 14a, and the intermediate transfer member 14 gradually becomes dirty. Then, the dirt such as toner adhered to the intermediate transfer member 14a adheres to the back surface of the transfer material P and causes the back surface stain of the transfer material P. The contamination of the intermediate transfer member 14a and the transfer material P
When image formation is performed with the cleaning blade CB separated from the intermediate transfer member 14a in order to prevent contamination of the back surface, the number of images formed after separation is counted, and the number of times reaches a predetermined value N3. Sometimes high voltage power supply HV1 and primary transfer device 1
4c is operated to remove deposits on the intermediate transfer member.
That is, the secondary transfer unit 14g charges the adhered matter on the intermediate transfer member to the opposite polarity to the toner, and then charges the back surface of the intermediate transfer member 14a to the opposite polarity to the toner by the primary transfer unit 14c, thereby charging the toner. The attached matter is moved to the photosensitive drum 10 by electrostatic force. Such a primary transfer device 14
c and the charging of the secondary transfer device 14g, the intermediate transfer member 1
The toner on 4a is transferred to the photosensitive drum 10, and the deposit on the intermediate transfer body 14a is removed. As a result, the surface of the intermediate transfer member 14a is cleaned, and the contamination of the intermediate transfer member 14a and the rear surface of the transfer material P are prevented. Then, the toner transferred to the photosensitive drum 10 is cleaned by the cleaning device 19. The predetermined value N3 is set according to various conditions as in the case of N1 and N2, but is usually set to about 100 to 1000. Note that the intermediate transfer member cleaning process may be executed by the operator pressing the intermediate transfer member cleaning button as appropriate without setting N3 in advance.

[0040]

In an image forming apparatus having an intermediate transfer member and having a double-sided image forming function and a single-sided image forming function, when one-sided image formation without transferring a toner image to the intermediate transfer member is continuously performed. This solves the problem that an undesirable phenomenon of turning up the cleaning blade of the intermediate transfer body cleaning device occurs. As a result, single-sided image formation can be performed without trouble using the image forming apparatus having the intermediate transfer member.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a mechanical configuration of an entire image forming apparatus according to an embodiment;

FIG. 2 is a block diagram of a control system of the image forming apparatus according to the first exemplary embodiment;

FIG. 3 is a block diagram of a control system of the image forming apparatus according to the second exemplary embodiment;

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum (toner image forming body) 14a intermediate transfer body 14c primary transfer unit 14g secondary transfer unit PC counter (counting means) PU toner image forming unit CB cleaning blade MS1, MS2, MS3 image forming mode selection button SC control Part SD solenoid

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Haneda Konica Corporation 2970 Ishikawacho, Hachioji-shi, Tokyo

Claims (6)

[Claims] A first mode in which a toner image formed on an image forming body is once transferred to an intermediate transfer body and then transferred from the intermediate transfer body to a transfer material to form an image on the transfer material; A second mode in which the toner image formed on the transfer member is transferred from the image forming member to a transfer material without transferring the toner image to the intermediate transfer member to form an image on the transfer material. Counting means for counting the number of continuous images formed in the printer, and blade turning-up preventing means for preventing turning of a cleaning blade of the intermediate transfer body cleaning device for cleaning the intermediate transfer body, wherein the count number by the counting means is a predetermined number. An image forming apparatus, wherein the blade turning-up preventing means is actuated when the number of rotations reaches a predetermined value. 2. The image forming apparatus according to claim 1, wherein said blade turn-over preventing means has a toner supply means for supplying toner to a surface of said intermediate transfer member. 3. The image forming apparatus according to claim 2, wherein the toner supply unit includes:
The image forming apparatus according to claim 2, further comprising: a toner image forming unit that forms a toner image on the image forming body; and a transfer unit that transfers the toner image on the image forming body to the intermediate transfer body. . 4. The apparatus according to claim 1, wherein the blade turning-up preventing means has a blade driving means for separating the cleaning blade from the intermediate transfer body, and the blade driving means when the number counted by the counting means reaches a predetermined number.
The image forming apparatus according to claim 1, wherein the cleaning blade is separated from the intermediate transfer body. 5. An image forming apparatus according to claim 1, further comprising: a removing unit configured to remove an adhered substance on the intermediate transfer body. The image forming apparatus according to claim 4, wherein the image forming apparatus is operated. 6. A first charging means for charging a surface of the intermediate transfer body, wherein a second charging means for charging a back surface of the intermediate transfer body at a position where the intermediate transfer body faces the image forming body. The image forming apparatus according to claim 5, further comprising a charging unit.