JPH06337598A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent toner filming on an intermediate transfer belt. CONSTITUTION:Besides a cleaner 22, the device is provided with a coating device for coating the surface of the intermediate transfer belt 19 with fine particles. The fine particles are lubricating-oil additive comprised of zinc stearate as the main component and, and this is used in the form of a plate-like coating agent which is obtained by melting, cooling and solidifying them. This coating device 36 is composed of: a brush roller 38 which is in contact with the coating agent 37 and slides over the coating surface, and a roller 39 which restricts an amount that the brush roller 38 presses the intermediate transfer belt 19 deeply; it is rotated by a brush-driving means. In this structure, by coating the surface of the intermediate transfer belt 19 with the zinc stearate, filming on the surface of the belt 19 is prevented and releasability from the surface of the belt 19 is improved, therefore a decrease in efficiency in transferring images from the surface of the belt 19 to the surface of recording paper is prevented.

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 such as a copying machine, a facsimile or a printer, and more specifically, a toner image from an image carrier for carrying a toner image which is a latent image visualized. The present invention relates to prevention of toner filming on an intermediate carrier in an image forming apparatus having an intermediate carrier that carries the toner.

[0002]

2. Description of the Related Art Conventionally, this type of intermediate carrier has been used in, for example, a color image forming apparatus. This type of intermediate carrier is similar to the image carrier composed of a photoconductor, even if the toner image is transferred to the image carrier of the next step, such as transfer paper as the final image carrier. Since residual toner remains, cleaning is required to remove the residual toner from the surface by the next imaging cycle.
As a cleaning device for the image bearing member and the intermediate bearing member, for example, a blade cleaning method in which the edge of a cleaning blade made of urethane rubber is pressed to scrape off the residual toner and a fur brush cleaning method using a bristle brush are known. In particular, the blade cleaning method is widely used because it has a simple mechanical structure and can configure a cleaning device at low cost. However, if toner or fine toner that has melted due to heat or pressure adheres to the surface of the intermediate carrier, it cannot be removed by the cleaning blade alone, and a toner filming layer (hereinafter referred to as the filming layer) must be gradually formed. There is. When this filming layer is formed, the transfer performance deteriorates and the image quality deteriorates. In particular, since an intermediate transfer member is used and the toner image is transferred twice or more between the photosensitive member and the final image bearing member, even a slight filming layer may lead to a large decrease in transfer efficiency as a whole. . Further, when the counter blade method is used, when the filming layer is formed, the friction coefficient with the cleaning blade increases, and the cleaning blade may be caught.

Therefore, Japanese Patent Laid-Open No. 214882/1990 proposes that a cleaning roller is provided downstream of the cleaning blade to rub the surface of the intermediate carrier to remove the filming layer. As a further improvement, in JP-A-2-262180, means for supporting the cleaning roller so that it can be brought into contact with and separated from the surface of the intermediate carrier is provided, and the cleaning roller is provided on the surface of the intermediate carrier every predetermined number of times of image formation. It has been proposed to bring them into contact and rub.

Although not related to the intermediate carrier, a small-diameter substance consisting of a lubricating oil additive is applied to the surface of the transfer drum carrying the transfer paper to form a film of this substance, whereby the surface of the transfer drum is formed. It has been proposed in JP-A-3-65973 to reduce the surface energy of the toner to facilitate removal of toner from this surface by a cleaning device.

[0005]

However, in the apparatus disclosed in Japanese Patent Laid-Open No. 214882/1990, there is a possibility that the intermediate carrier may be rubbed too much by the rubbing force of the cleaning roller. Further, even when the number of times of rubbing by the cleaning roller is set as in the apparatus disclosed in Japanese Patent Laid-Open No. 2-262180, the generation state of the filming layer varies depending on the usage conditions of the image forming apparatus. May not be able to respond adequately.

The present invention has been made in view of the above problems, and an object of the present invention is to temporarily carry a toner image from an image carrier for carrying a toner image in which a latent image is visualized. An object of the present invention is to provide an image forming apparatus capable of effectively preventing toner filming on an intermediate carrier.

[0007]

In order to achieve the above-mentioned object, the invention of claim 1 is an image carrier for carrying a toner image in which a latent image is visualized, and an image carrier transferred from the image carrier. An intermediate carrier carrying a toner image, a transfer means for transferring the toner image from the image carrier to the intermediate carrier, and a toner image transferred from the intermediate carrier to a final toner image carrier or another intermediate carrier. An image forming apparatus having a transfer unit for removing the residual toner on the intermediate carrier,
A coating device for coating fine particles having a function of preventing toner filming is provided on the surface of the intermediate carrier. Here, as the fine particles having a toner filming preventing function, for example, the above-mentioned JP-A-3-659 is used.
It is possible to use a material such as a small-diameter substance made of a lubricating oil additive disclosed in Japanese Patent Laid-Open No. 73-73 that lowers the surface energy of an object to be coated to facilitate toner removal by a cleaning device. Further, a substance other than the small-diameter substance made of a lubricating oil additive can be used as long as the toner can be easily removed by the cleaning device regardless of whether the surface energy of the object to be coated is lowered. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the coating device includes a coating agent in which the fine particles are solidified, and a coating means for finely coating the coating agent on the surface of the intermediate carrier. It is characterized by being composed of and. Here, the application means can be configured to apply the fine particles by rubbing the application agent into fine particles by, for example, rotating a brush roller, and bringing the brush roller into contact with the surface of the intermediate carrier. When such a brush roller is used, it is desirable to provide a contacting / separating means for the brush roller so that the contact between the brush roller and the intermediate carrier can be released when the application is not performed. Further, it is desirable to provide a regulating means for regulating the amount of the brush portion of the brush roller biting into the surface of the intermediate carrier. According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, as the cleaning device, the residual toner is removed from the surface of the intermediate carrier, and the fine particles coated on the surface are at least smoothed. A part that can pass through the rubbing part is used for cleaning with a rubbing member for the surface, and a coating operation is performed on the part of the surface cleaned by the cleaning device, and the coating operation is performed. A control means for controlling the coating device and the cleaning device is provided so that the cleaning operation is performed until at least a predetermined portion of the surface coated with the fine particles has passed through the portion facing the cleaning device. It is characterized by that. Here, for example, a cleaning blade can be used as the rubbing member of the cleaning device. Further, the predetermined portion of the surface of the intermediate carrier coated with the fine particles in the coating operation is
It is a portion of the surface of the intermediate carrier on which fine particles are applied for use in carrying a toner image. For example, when fine particles are applied to the entire circumference of the surface of the intermediate carrier in order to carry the toner image, the cleaning operation is performed until the entire circumference after application of the fine particles has passed through the portion facing the cleaning device. Let it be done. According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, when the cumulative number of image formations from the end of the previous application operation reaches a predetermined number or more at the end of a series of image forming operations, application to the application unit is performed. And a control means for causing the coating means to perform the coating operation during each image forming operation even during a series of image forming operations when the cumulative number of image formation times reaches a predetermined number. It is characterized by that. According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the fine particle carrier is driven so that the surface of the coating device moves in the same direction as the surface of the intermediate carrier at a portion facing the intermediate carrier. It is characterized in that the member is configured to apply fine particles to the surface of the intermediate carrier. According to a sixth aspect of the invention, in the image forming apparatus according to the first aspect, as the fine particles, those containing zinc stearate as a main component are used. According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the cumulative number of image formations from the end of the previous coating operation is a predetermined number or more when the device is reset after the jam processing and / or when the power is turned on. In this case, control means for performing the coating operation is provided. here,
It is desirable that the coating operation at the time of resetting the apparatus after the jam processing and / or at the time of turning on the power supply is performed before the image forming apparatus is set to the image forming ready state, for example, before the image forming ready display is made to the operator.

[0008]

According to the first aspect of the present invention, the toner image is formed even when the toner image is transferred to the intermediate carrier by coating the surface of the intermediate carrier with the fine particles having the function of preventing toner filming by the coating device. The toner is prevented from firmly adhering to the surface of the intermediate carrier, or the residual toner is easily removed by a cleaning device to prevent toner filming.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a coating agent in which the fine particles are solidified is used, and the fine particles are finely divided by a coating means and coated on the surface of the intermediate carrier.

According to a third aspect of the invention, in the image forming apparatus according to the first aspect, the controller controls the coating device and the cleaning device to coat the surface of the intermediate carrier cleaned by the cleaning device. The operation is performed, and the cleaning operation is performed until at least a predetermined portion of the surface coated with the particles in the coating operation has passed through the portion facing the cleaning device.
Then, as the cleaning device, the residual toner is removed from the surface of the intermediate carrier, and the fine particles coated on the surface are evened so that at least a part thereof can pass through the rubbing portion. A cleaning member is used to clean the fine particles, and when the surface of the intermediate carrier coated with the fine particles in the coating operation passes through the sliding portion of the sliding member, the fine particles are leveled and the intermediate carrier is carried. Increases adhesion to the body surface.

According to a fourth aspect of the invention, in the image forming apparatus of the first aspect, the control means causes the cumulative number of image formations since the end of the previous coating operation to become a predetermined number or more at the end of the series of image forming operations. When the cumulative number of image formations reaches a predetermined number, the coating means is caused to perform the coating operation during each image forming operation. Let it be done.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the fine particle carrying member is driven so that the surface thereof moves in the same direction as the surface of the intermediate carrier at the portion facing the intermediate carrier. Then, fine particles are applied to the surface of the intermediate carrier.

According to a sixth aspect of the present invention, in the image forming apparatus according to the first aspect, as the fine particles, those containing zinc stearate as a main component are used, whereby even if the toner image is transferred to the intermediate carrier. The toner forming the toner image is prevented from firmly adhering to the surface of the intermediate carrier, or the residual toner is easily removed by the cleaning device to prevent toner filming.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the control means causes the cumulative image formation from the end of the previous coating operation at the time of resetting the apparatus after the jam processing and / or at the time of turning on the power. When the number of times is a predetermined number or more, the coating operation is performed.

[0015]

EXAMPLE An example in which the present invention is applied to a color copying machine using an intermediate transfer belt as an intermediate carrier will be described below. FIG. 1 is an enlarged view around a photoconductor / intermediate transfer belt of a color copying apparatus according to this embodiment, and FIG. 2 is a schematic configuration diagram of the color copying apparatus. First, an outline of the configuration and operation of this device will be described. A color image reading device (hereinafter, referred to as a color scanner) 1 forms an image of a document 3 on a color sensor 7 via an illumination lamp 4, a mirror group 5, and a lens 6 to obtain color image information of the document, for example, Each color separation light of blue (Blue, hereinafter B), green (Green, hereinafter G), and red (Red, hereinafter R) is read and converted into an electrical image signal. And
An image processing unit (not shown) based on the B, G, and R color-separated image signal intensity levels obtained by the color scanner 1.
Color conversion processing is performed with black (hereinafter, referred to as Bk), cyan (Cyan, hereinafter referred to as C), and magenta (Ma).
genta, hereinafter referred to as M), and yellow (Yellow, hereinafter referred to as Y) color image data are obtained. Using this color image data, Bk, C, M, and Y are visualized by a color image recording device (hereinafter, referred to as a color printer) 2 described below, and these visualized images are superposed.
Form a full-color image.

Next, the outline of the color printer 2 will be described. The writing optical unit 8 converts the color image data from the color scanner 1 into an optical signal, performs optical writing corresponding to the original image, and forms an electrostatic latent image on the photosensitive drum 9. The unit 8 includes a laser 8a and its light emission drive control unit (not shown), a polygon mirror 8b and its rotation motor 8c, an f / θ lens 8d and a reflection mirror 8e.
Etc. The photoconductor drum 9 rotates counterclockwise as indicated by an arrow, and around the photoconductor drum 9, a photoconductor cleaning unit (including a pre-cleaning static eliminator) 10, a static eliminator 11, a charger 12, a potential sensor 13, and a Bk developing device. 14, a C developing device 15, an M developing device 16, a Y developing device 17, an optical sensor 18 for detecting a development density pattern, an intermediate transfer belt 19 and the like are arranged.

Each developing unit pumps up the developing sleeve (14a, 15a, 16a, 17a) which rotates by bringing the ear of the developer into contact with the surface of the photoconductor 9 for developing the electrostatic latent image.・ Development paddle (14
b, 15b, 16b, 17b), and a toner concentration sensor (14c, 15c, 16c, 17c) for the developer.

Next, the outline of the copying operation will be described by taking the example of the developing operation order (color image forming order) as Bk, C, M, and Y (however, the image forming order is not limited to this. ). First, in the standby state, all of the four developing devices are in a development inactive state due to, for example, cutting of the developer on the developing sleeve (hereinafter, description will be made assuming that the developer is inactive by cutting the developer. To). When the copy operation is started, the color scanner 1 starts reading Bk image data at a predetermined timing, and optical writing by a laser beam and latent image formation start based on the image data (hereinafter, electrostatic image based on Bk image data). The latent image is referred to as a Bk latent image. C, M, and Y are referred to as a C latent image, an M latent image, and a Y latent image, respectively). Before the latent image front end reaches the developing position of the Bk developing device 14 so that the front end of the Bk latent image can be developed, the developing sleeve 14a is started to rotate and the agent is speared to form the Bk latent image. Develop with Bk toner. After that, the developing operation of the Bk latent image area is continued, and when the trailing edge of the latent image passes the Bk developing position, the Bk latent image area is quickly changed to
The agent on the developing sleeve 14a is cut off to bring the developing sleeve into the inoperative state. This is completed at least before the leading edge of the C latent image by the next C image data arrives. It should be noted that the brush cutting is performed by switching the rotation direction of the developing sleeve 14a to the opposite direction to that during the developing operation. Alternatively, the developing sleeve 14a alone or the entire developing device may be separated from the photoconductor.

The Bk toner image formed on the photosensitive member 9 is transferred onto the surface of the intermediate transfer belt 19 which is driven at the same speed as the photosensitive member (hereinafter, the toner image transfer from the photosensitive member to the intermediate transfer belt is called belt transfer). ). The belt transfer is performed by applying a predetermined bias voltage to the transfer bias roller 20 while the photoconductor 9 and the intermediate transfer belt 19 are in contact with each other. It should be noted that, on the intermediate transfer belt 19, the Bk, C, M, and Y toner images sequentially formed on the photoconductor 9 are sequentially aligned on the same surface to form a belt transfer image of four-color superimposition. , Perform bulk transfer to transfer paper. This intermediate transfer belt unit will be described later.

On the side of the photosensitive member 9, the Bk process is followed by the C process, but the C image data reading by the color scanner 1 is started at a predetermined timing, and the C latent image is formed by writing laser light by the image data. C developing device 1
Reference numeral 5 indicates that the developing sleeve 15a is started to rotate to raise the agent after the trailing edge of the previous Bk latent image has passed and before the leading edge of the C latent image has reached the developing position. Latent image C
Develop with toner. After that, the development of the C latent image area is continued, and when the trailing edge of the latent image passes, the agent cutting on the C developing sleeve 15a is performed as in the case of the Bk developing device. This is also completed before the leading edge of the next M latent image arrives. In each of the M and Y steps, the operations of image data reading, latent image formation and development are the same as those of Bk and C described above.
It is performed in the same manner as the step of.

Now, the intermediate transfer belt unit will be described. The intermediate transfer belt 19 is stretched around a drive roller 21, a belt transfer bias roller 20, and a group of driven rollers (roller 35, roller 42, etc.), and is drive-controlled by a drive motor (not shown). A specific drive control method will be described later. The belt cleaning unit 22 includes an entrance seal 22a and a rubber blade 22.
b, entrance seal from belt and rubber blade 2
It is composed of the contacting / separating mechanism 22c of 2b, etc., and while the belt transfer of the second, third, and fourth colors after the belt transfer of the Bk image of the first color, the entrance / separation mechanism 22c seals the entrance from the belt surface. 22a and the rubber blade 22b are separated from each other.

The paper transfer unit 23 includes a paper transfer bias roller 23a, a roller cleaning blade 23b,
And a belt contact / separation mechanism 23c. The bias roller 23a is normally separated from the surface of the belt 19, but the contact / separation mechanism 23c is arranged at a timing when the superimposed image of four colors formed on the surface of the intermediate transfer belt 19 is collectively transferred to the transfer paper. Pressed by the roller 2
A predetermined bias voltage is applied to 3a to perform transfer to paper. The transfer paper 24 is fed by the paper feed roller 25 and the registration roller 26 at the timing when the leading end of the four-color superimposed image on the intermediate transfer belt surface reaches the paper transfer position.

As a concrete drive control method of the intermediate transfer belt 19 described above, the following three methods are conceivable as the operation method after the belt transfer of the Bk toner image of the first color is completed to the end. The intermediate transfer belt 19 is driven by one of the above methods, or by efficiently combining a plurality of methods according to the copy size in terms of copy speed. (1) First, a constant speed forward movement method will be described as a first method. Even after the Bk toner image is transferred onto the belt, it continues to move at a constant speed. Then, when the front end position of the Bk image on the surface of the belt 19 reaches the belt transfer position of the contact portion with the photosensitive member 9 again, on the photosensitive member 9 side, the front end portion of the next C toner image is exactly at that position. , The image is formed at the right time. As a result, the C image is accurately aligned with the Bk image and is transferred onto the intermediate transfer belt 19 in a superimposed manner. After that, the same operation is followed to the M, Y image process,
A belt transfer image of four colors is obtained. The four-color Y toner image belt transfer process is continued, and the four-color superimposed toner images on the belt surface are collectively transferred onto the transfer paper 24 as described above while moving forward. (2) Next, a skip forward method will be described as a second method. When the belt transfer of the Bk toner image is completed, the belt 19 is separated from the surface of the photoconductor 9, and the belt 19 is skipped at a high speed in the same direction to move the predetermined amount, and the original forward speed is restored. Further, thereafter, the belt 19 is brought into contact with the photosensitive member 9 again. When the front end position of the Bk image on the surface of the belt 19 reaches the belt transfer position again, an image is formed on the photosensitive member 9 side with a timing so that the front end of the C toner image is exactly at that position. There is. As a result, the image of C is transferred onto the belt while being accurately aligned with the image of Bk and superposed. After that, the same operation is performed to proceed to the M and Y image process.
Obtain a belt transfer image with color overlap. Following the Y toner image belt transfer process for the fourth color, the four color superposed toner images on the surface of the belt 19 are collectively transferred onto the transfer paper 24 at the same forward speed. (3) Next, a reciprocating (quick return) system will be described as a third system. When the belt transfer of the Bk toner image is completed, the belt 19 is separated from the surface of the photoconductor 9, and the forward movement is stopped, and at the same time, the belt 19 is returned at a high speed in the opposite direction. In the return, the leading end position of the Bk image on the surface of the belt 19 passes through the position corresponding to the belt transfer in the opposite direction, and after moving a preset distance, it is stopped and put in the standby state. Next, when the front end portion of the C toner image on the side of the photoconductor 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is restarted in the forward direction. Belt 1 again
9 is brought into contact with the surface of the photoreceptor 9 again. Also in this case, the belt C is transferred under the condition that the C image is accurately overlapped with the Bk image on the surface of the belt 19. After that, the same operation is performed to proceed to the Y and M image process.
Obtain a belt transfer image with color overlap. Following the belt transfer process for the 4th Y toner image,
The belt 19 moves forward at the same speed without returning.
The four-color superimposed toner images on the surface are collectively transferred onto the transfer paper 24.

The transfer paper 24 on which the four-color superimposed toner images have been collectively transferred from the surface of the intermediate transfer belt as described above is conveyed to the fixing device 28 by the paper conveying unit 27, and the fixing roller controlled to a predetermined temperature. 28a and pressure roller 28
In b, the toner image is fused and fixed and is carried out to the copy tray 29. This gives a full color copy.

The surface of the photoconductor 9 after the belt transfer is cleaned by the photoconductor cleaning unit 10.
Further, the static elimination lamp 11 uniformly eliminates the static electricity. Further, the intermediate transfer belt 19 after the toner image is transferred onto the transfer paper 24 is
In the cleaning unit 22, the contact / separation mechanism 22c again presses the rubber blade 22b to clean the surface.

At the time of repeat copy, the color scanner 1
The operation and the image formation on the photosensitive member 9 proceed to the second Bk (first color) image process at a predetermined timing after the first Y (fourth color) image process. Further, in the intermediate transfer belt 19, after the batch transfer process of the first four-color superimposed image onto the transfer paper, the surface of the intermediate transfer belt 19 is moved to the area cleaned by the rubber blade 22b of the cleaning unit 22 and the second sheet. The Bk toner image is transferred on the belt. After that, the same operation as the first sheet is performed. The transfer sheet cassettes 30, 31, 32, and 33 store transfer sheets of various sizes, and when the transfer sheet cassettes designated by an operation panel (not shown) store the size sheets, the registration roller 26 is directed toward the registration roller 26 at a certain timing. The paper is fed and transported. 34 is OHP
This is a manual feed tray for paper and thick paper.

The above is the description of the copy mode in which four full colors are obtained, but in the case of the three-color copy mode and the two-color copy mode, the same operation as above is performed for the designated color and the number of times. It will be. In the case of the single-color copy mode, only the developing device for that color is kept in the developing operation state until the predetermined number of sheets are finished, and the intermediate transfer belt 19
Is driven in the forward direction at a constant speed while being in contact with the surface of the photoconductor 9, and the rubber blade 2 of the cleaning unit 22 is driven.
The copying operation is performed while 2b is also in contact with the belt 19.

Next, the application of fine particles to the transfer belt 19 for preventing toner filming will be described.
In this embodiment, a lubricating oil additive containing fine particles of zinc stearate as a main component is melted, cooled and solidified to be used as a coating agent. Coating device 36 in this embodiment
As shown in FIG. 3A, a plate-shaped coating agent 37 in which a lubricating oil additive is solidified, a brush roller 38 that contacts the coating agent and rubs the surface of the coating agent, and this brush roller Three
It is composed of a roller 39 for controlling the amount of biting of the intermediate transfer belt 8 into the intermediate transfer belt 19. FIG. 3B shows a brush roller 3
It is a longitudinal cross-sectional view of 8 parts. Further, the brush roller 38 can be rotated counterclockwise in FIG. 3 by a brush driving means (not shown). Then, the coating device 36 includes the support shaft 4
It is supported by the main body side plate about 0, and the entire coating device 36 can be brought into contact with and separated from the position of the driven roller 35 of the intermediate transfer belt 19 by the contacting / separating means 43 such as a solenoid. When the applicator is not in operation, the spring 41
Thus, the brush roller 38 is held at a position separated from the surface of the intermediate transfer member. During operation, the solenoid causes the entire coating device to rotate about the support shaft 40, and the brush roller 38 contacts the surface of the intermediate transfer belt 19. At this time, the rollers 39 provided at both ends of the brush roller shaft
However, the brush roller 38 bites into the intermediate transfer belt 19 until it comes into contact with the surface of the intermediate transfer belt 19 on the driven roller 35. In the illustrated example, the outer diameter of the brush roller 38 is 18 m.
Since m and the outer diameter of the roller are 15 mm, the biting amount of the brush roller 38 and the intermediate transfer belt 19 is 1.5 mm. The composition of the brush fibers is 300 denier / 48 filaments, the flocking density is 50,000 fibers / inch ² , the bristle length is 5 mm, and the amount of the brush roller 38 and the coating material to be bitten is set to 1.5 mm.

The coating device 36 constructed as described above is
Since the coating agent 37 and the brush roller 38 are always in contact with each other, the surface of the coating agent is rubbed and polished by the brush fibers at the same time as the rotation of the brush roller 38. The fine particles of the coating agent scraped off by the brush fibers uniformly adhere to the surface of the brush roller 38. This brush roller 38 is connected to the intermediate transfer belt 19
By rubbing the surface, the solidified coating agent can be applied to the surface of the intermediate transfer belt 19 as fine particles. Further, at this time, since the amount of biting of the brush and the belt 19 is kept constant by the rollers, it is possible to always apply the coating uniformly. With the above-described structure, by applying zinc stearate onto the intermediate transfer belt 19, filming on the belt 19 is prevented, and the releasability of the surface of the belt 19 is improved. It is possible to prevent a decrease in the transfer rate from the top to the recording paper.

Next, the operation of the coating apparatus will be described with reference to FIGS. 4 and 5. In the final cleaning step of the intermediate transfer belt 19 at the end of the series of copying operations, the rubber blade 22b is brought into contact with the rotating belt 19 (starting the cleaning step). When the position where cleaning has started passes the position of the coating device, the brush roller 3
The rotation of No. 8 is started, and at the same time, the brush roller 38 is brought into contact with the solenoid by turning on (starting the coating process). After a certain application time (about 10 seconds in this embodiment, about 3 rotations of the belt), the brush roller 38 is separated by the solenoid OFF, and the brush rotation is stopped. FIG. 4A is an explanatory view at the moment when the brush roller 38 is separated. Reference numeral A indicates a belt portion facing the brush roller 38 at the moment when the brush roller 38 is separated, and reference numeral B indicates that fine particles are applied. The area, reference numeral C, indicates the area rubbed by the rubber blade 22b. The belt 19 continues to rotate even after the brush roller 38 is separated. As shown in FIG. 4B, when the belt portion A passes through the rubber blade 22b, the rotation of the belt 19 is stopped and the rubber blade 22b is removed. Cancel (end coating process and cleaning process). Such control is performed by the control unit (not shown) by the solenoids 2 described above.
2c, 43 and the belt drive mechanism can be controlled by turning them on and off. As described above, the brush roller 38 is brought into contact only with the cleaned area of the belt 19,
This is to prevent the residual toner on the belt 19 from adhering to the brush roller 38. When the brush roller 38 is soiled with residual toner or the like, the coating agent cannot be effectively applied, and at the same time, the toner is scattered from the brush roller 38 to contaminate the inside of the machine. The reason why the rubber blade 22b again rubs the entire area to which the coating agent has been applied by the brush roller 38 is as follows. That is, as schematically shown in FIG. 4A and FIG. 5, the fine particles of the coating agent after adhering to the surface of the belt 19 from the brush roller 38 adhere in a relatively non-uniform state. Is also considered weak. Therefore, by repeating the copying operation, the coating particles are reduced from the surface of the belt 19 and the filming substance is easily attached, so that it is necessary to frequently perform the coating operation. Therefore, the surface of the belt 19 to which the coating material is attached is rubbed with the rubber blade 22b. Since the backup roller 42 is provided at the contact position of the rubber blade 22b, the contact state of the blade 22b can be stably maintained. Toner particles are accumulated in the blade edge portion, but since the coating agent fine particles are extremely smaller than the toner particles, they pass through the toner reservoir and reach the edge portion. The coating agent fine particles accumulated on the edge portion can pass through a minute gap between the surface of the belt 19 and the edge portion, and are rubbed on the surface of the belt 19 at the time of passage to adhere uniformly and strongly. In FIG. 5, reference symbol T indicates toner and reference symbol B indicates coated fine particles. According to a study made by the present inventors, when the brush roller 38 is only applied, the effect lasts only during the copying operation of about 20 sheets after the application, whereas the brush roller 38 under the same conditions is used. When the rubbing treatment by the blade 22b is performed after the coating operation by
The effect duration could be extended to 00.

Next, the execution timing control (execution interval control) of the coating operation will be described. When the coating amount of the coating agent is excessive, the releasability of the surface of the intermediate transfer belt 19 is improved too much, and the transfer rate from the photoconductor onto the intermediate transfer belt 19 is reduced. Therefore, a predetermined number of sheets is set in advance, and when a series of copying operations is completed when the cumulative number of copies from the end of the previous coating operation is equal to or more than a predetermined number, or when the number of continuous copies reaches a predetermined number of copies. The coating operation is executed between the operations. As a result, the number of interruptions of the copy operation due to the execution of the coating operation can be reduced as much as possible, and the efficiency of the copy operation can be prevented from lowering. For example, the maximum set number of sheets at the time of normal copying is 99 sheets, and the above-mentioned coating operation is executed at the end of a series of copying operations after the cumulative number of copied sheets reaches 50 sheets or more.
Under these setting conditions, the maximum is 148 (49 + 99)
The coating operation is performed once every two seconds. Also, ADF
When an (automatic document feeder) or a sorter is used, the copying operation of 99 sheets or more can be continuously performed, so that the coating amount is insufficient only by the coating operation at the end of the copying operation. Therefore, even in such a case, in order to keep the amount of coating agent adhered within a certain range, during the copying operation of the 150th sheet and the 151st sheet during the continuous copying operation,
Perform the coating operation. The set number of copies, such as 50 sheets or 150 sheets, is appropriately set according to the coating conditions of the coating agent and the like.

FIG. 6 is a flow chart showing an example of the execution timing control. First, when the main switch of the copying machine is turned on (step 1), the content NT of the cumulative copy number counter of the copy executed after the completion of the previous coating operation is called up, and the first set copy number NA (50 copies in the above setting condition example). ) (Step 2,
3). If it is determined that the number of copies is not less than the first set copy number NA, the application operation is executed, the content NT of the cumulative copy number counter is set to 0, the rotation of the belt 19 is stopped, and the process returns to the standby (steps 14, 15, 16). , 4). On the other hand, when it is determined that the cumulative number of copies NT is smaller than the first set number of copies NA, the copying machine is put on standby, the number of copy sets ns is read using the ten-key pad of the operation board (not shown), and the copy start is started. Wait for the button (print SW) to be pressed (steps 4, 5)
6). When the copy start button is pressed, the content n of the copy number counter is set to 0, the copy operation is executed, the content n of the copy number counter and the content NT of the cumulative copy number counter are incremented, and then the content NT of the cumulative copy number counter is And the second set number of copies NB (150 in the above setting condition example) are compared (steps 8, 9, 1).
0, 11). If they are not equal, the content n of the copy number counter is compared with the set number ns to determine whether or not a series of copies of the set number n has been completed (step 12). Until the copying is completed or it is judged at step 11 that the content NT of the cumulative copy number counter is equal to the second set copy number NB, the copying operation is executed while incrementing each counter. If it is determined in step 12 that the series of copies of the set number n has been completed, the contents NT of the cumulative copy number counter for copying are compared with the first set number of copies NA to determine whether the first set number of copies NA or more. If so, the coating operation is executed and the content NT of the cumulative copy number counter is set to 0.
After that, the rotation of the belt 19 is stopped and the operation returns to the standby (steps 13, 14, 15, 16, 4). On the other hand, when it is determined in step 13 that the content NT of the cumulative copy number counter is smaller than the first set copy number NA, the rotation of the belt 19 is stopped and the process returns to the standby (steps 13, 16, 4). On the other hand, during this series of copying, when it is judged in step 11 that the content NT of the cumulative copy number counter is equal to the second set copy number NB, the coating operation is executed at that point (step 18), and the cumulative copy number counter After the content of is set to 0 (step 17), the copy operation is restarted (step 8).

According to this example of the coating operation execution timing control, the cumulative copy number counter is reset when the coating operation is completed, and the cumulative copy number counter is compared with the first set copy number after the main switch is turned on. Since it is determined whether or not the coating operation is necessary, if the recording paper is jammed or the power is forcibly stopped during the coating operation, the coating operation can be executed again when the power is next turned on.

As described above, according to the present embodiment, the amount of the coating material deposited on the belt 19 can be maintained within a certain range for a long period of time. Further, when the rotation direction of the brush roller driving means is set so that the traveling direction of the surface of the belt 19 and the traveling direction of the outer peripheral surface of the brush roller 38 are the same when the intermediate transfer belt 19 and the brush roller 38 are in contact with each other. The load on the brush roller driving means is reduced, and the driving means can be downsized. Various materials can be considered as the coating agent, but when a coating agent containing zinc stearate as a main component is used, it is possible to prevent uneven transfer efficiency caused by uneven coating amount.

[0035]

According to the first aspect of the present invention, the toner filming is prevented on the intermediate carrier so that even if the toner image is transferred to the intermediate carrier, the toner forming the toner image is firmly adhered to the surface of the intermediate carrier. The adhesion is prevented or the residual toner is easily removed by a cleaning device. Therefore, the toner filming is prevented by rubbing with a cleaning roller provided in addition to the cleaning blade. Compared with the invention disclosed in Japanese Unexamined Patent Publication No. 214882, it is possible to avoid a situation in which the transfer performance is changed and the image quality is deteriorated due to excessive rubbing of the intermediate carrier.
Further, as compared with the invention disclosed in JP-A-2-214882, the generation of the filming layer is less likely to be affected by the usage conditions of the image forming apparatus, and the adaptability to the usage environment can be improved.

According to the second aspect of the invention, since the coating agent in which the fine particles are solidified is used, and the fine particles are made into fine particles by the coating means and applied to the surface of the intermediate carrier, for example, the above-mentioned Japanese Patent Laid-Open No. The coating amount can be stabilized by a simple coating agent storage mechanism or fixed amount coating mechanism as compared with the case where the fine particles are stored in the image forming apparatus and used for coating as disclosed in JP-A-65973. . Further, the replenishment work of the coating agent can be performed relatively easily.

According to the third aspect of the present invention, since the coating operation is performed on the portion of the surface of the intermediate carrier that has been cleaned by the cleaning device, the coating operation is performed on the portion of the surface of the intermediate carrier that has not been cleaned. As compared with the case of carrying out, it is possible to reduce the toner stain on the coating device. Further, the predetermined cleaning device is used, and the cleaning operation is performed until at least a predetermined portion of the surface coated with the particles by the coating operation has passed through the portion facing the cleaning device. Can be made uniform and the adhesive force to the surface of the intermediate carrier can be increased. The function of increasing the adhesion force of the fine particles to the application target is a cleaning device including a fur brush roller used together with a lubricating oil additive fine particle supply device in the device disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-65973. That is something that cannot be demonstrated.

According to the fourth aspect of the present invention, when the cumulative number of image formations since the end of the previous application operation exceeds the predetermined number at the end of the series of image formation operations, the application means is made to perform the application operation. In such a case, even in an image forming apparatus in which the image forming operation needs to be interrupted due to the coating operation between the image forming operations, it is possible to perform fine particle formation without interrupting the image forming operation for the coating operation. The toner filming prevention effect by the above can be maintained to some extent over a long period of time. Further, when the above-mentioned coating device is made to perform the coating operation during each image forming operation even during the series of image forming operations when the cumulative number of image forming times reaches a predetermined number, toner filming prevention by fine particles is prevented. The effect can be maintained well over a long period of time. Further, when both of the control means are adopted, the coating operation required during each image forming operation is performed during the series of image forming operations rather than the predetermined number of times for the necessity of the coating operation at the end of the series of image forming operations. For example, by setting the predetermined number of times for the failure to a larger value, for example, the application operation is usually performed only when the number of times is smaller than the smaller number of times at the end of a series of copying, and a considerably large amount is applied. When the larger number of times is reached in the middle of continuous copying, the coating operation is performed between the copies to prevent the formation of a filming layer, so that the copying operation is interrupted for the coating operation. Even in the apparatus, the toner filming prevention effect can be favorably maintained for a long period of time while the interruption of the copying operation for the coating operation is minimized.

According to the invention of claim 5, the fine particles are applied to the surface of the intermediate carrier by the fine particle carrying member driven so that the surface moves at the portion facing the intermediate carrier.
Stable application can be performed with a simple configuration of the application device. Further, since this fine particle carrying member is driven so that the surface moves in the same direction as the surface of the intermediate carrier at the portion facing the intermediate carrier, as compared with the case where it is driven so as to move in the opposite direction. The load on the drive source can be reduced.

According to the sixth aspect of the invention, in the image forming apparatus of the first aspect, since fine particles containing zinc stearate as a main component are used as the fine particles, the coatability is good and uneven coating can be prevented.

According to the invention of claim 7, when the device is reset after the jam processing and / or when the power is turned on, when the cumulative number of image formations from the end of the previous coating operation is a predetermined number or more, the coating is performed. Since the operation is performed, even if the coating operation is interrupted due to a jam detection or the apparatus being stopped by the operator turning off the power, the coating operation can be reliably completed by resetting the apparatus or turning on the power after the jam processing. .

[Brief description of drawings]

FIG. 1 is an enlarged view around a photoconductor / intermediate transfer belt of a color copying apparatus according to an embodiment.

FIG. 2 is a schematic configuration diagram of the color copying apparatus.

FIG. 3A is a schematic configuration diagram of a coating device 36 of the color copying apparatus. (B) is a brush roller 38 of the coating device 36
Sectional drawing of a part.

4A and 4B are explanatory views of the operation of the coating device.

FIG. 5 is an explanatory diagram of a cleaning blade contact portion of the cleaning device 22.

FIG. 6 is a flowchart of execution timing control of a coating operation.

[Explanation of symbols]

 9 Photoreceptor Drum 10 Photoreceptor Cleaning Unit 10a Pre-cleaning Charger 10b Brush Roller 10c Rubber Blade 11 Charger Lamp 12 Charger 13 Potential Sensor 14 Black Developer 15 Cyan Developer 16 Magenta Developer 17 Yellow Developer 19 Intermediate Transfer Belt 20 Belt transfer bias roller 21 Belt drive roller 22 Belt cleaning unit 22a Entrance seal 22b Rubber blade 22c Solenoid 23 Paper transfer unit 23a Paper transfer bias roller 23b Roller cleaning blade 23c Contact / separation mechanism 35 Driven roller 36 Coating device 37 Coating agent 38 Brush roller 39 Roller 40 Spindle 41 Spring 42 Driven roller 43 Solenoid

Claims (7)

[Claims] 1. An image carrier for carrying a toner image in which a latent image is visualized, an intermediate carrier for carrying the toner image transferred from the image carrier, and the image carrier to the intermediate carrier. In an image forming apparatus having a transfer means for transferring a toner image and a transfer means for transferring a toner image from the intermediate carrier to a final toner image carrier or another intermediate carrier, the residual toner on the intermediate carrier is removed. And a coating device for coating the surface of the intermediate carrier with fine particles having a toner filming preventing function. 2. The coating device comprises: a coating agent obtained by solidifying the fine particles; and a coating means for coating the surface of an intermediate carrier with the coating agent as fine particles. 1. The image forming apparatus of 1. 3. As the cleaning device, the residual toner is removed from the surface of the intermediate carrier, and the fine particles applied on the surface are evened so that at least a part thereof can pass through the rubbing portion. A device that performs cleaning with a rubbing member for the surface is used, and a coating operation is performed on a portion of the surface that has been cleaned by the cleaning device, and among the surfaces that have been coated with fine particles by the coating operation. 2. The image forming apparatus according to claim 1, further comprising control means for controlling the coating device and the cleaning device so that the cleaning operation is performed until at least a predetermined portion has passed through a portion facing the cleaning device. apparatus. 4. A control means for causing the coating means to perform the coating operation when the cumulative number of image formations since the end of the previous coating operation reaches or exceeds a predetermined number at the end of the series of image forming operations, and / or The image forming apparatus according to claim 1, further comprising control means for causing the coating means to perform the coating operation between the image forming operations even during a series of image forming operations when the cumulative number of image forming times reaches a predetermined number. Forming equipment. 5. A fine particle carrying member that drives the coating device so that the surface thereof moves in the same direction as the surface of the intermediate carrier at a portion facing the intermediate carrier, and the fine particles are applied to the surface of the intermediate carrier. It is constituted so that it may be applied.
Image forming device. 6. The image forming apparatus according to claim 1, wherein the fine particles are those containing zinc stearate as a main component. 7. A control means for performing a coating operation when the cumulative number of image formations from the end of the previous coating operation is equal to or more than a predetermined number at the time of resetting the apparatus after the jam processing and / or when the power is turned on. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.