JPH1138786A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the image drift caused by the electrostatic attractive and shearing forces at the time of a transfer and resolve a defective transfer such as a hollow phenomenon by setting the linear velocities of an image carrier and an intermediate transfer body respectively to eliminate the displacement and distortion generated by the electrostatic attractive and shearing forces between the image carrier and the intermediate transfer body at the time of a primary transfer. SOLUTION: A velocity fluctuation is reduced to prevent an image drift, and a photoreceptor drum 9 and an intermediate transfer belt 19 are merely made slippery to realize this state. A lubricant 37 is applied to at least one of the photoreceptor drum 9 and the intermediate transfer belt 19. The lubricant 37, e.g. zinc stearate, arranged to be brought into contact with the brush roller 10-2 of a photoreceptor cleaning unit 10 is applied to the photoreceptor drum 9. The lubricant 37 is applied to the intermediate transfer belt 19 by a coating device 36 constituted of the lubricant 37 cooled and solidified with the zinc stearate and a brush 38.

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 printer, and a facsimile, and more particularly, to an image forming apparatus, an intermediate transfer body, and an electrostatic field between an intermediate transfer body and a final transfer body. The present invention also relates to an image forming apparatus having improved transfer performance in a transfer step of transferring a toner image formed on the image carrier to a final transfer member via an intermediate transfer member.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile, etc., for example, an electrophotographic image forming apparatus, a transfer paper as a recording material is formed by transferring a visible toner image formed on an image carrier, for example, a photoreceptor. The method of transferring the image to a medium is well known. In addition, another transfer step is included in the process of transferring from the photoreceptor to the transfer paper, and the primary transfer from the photoreceptor to the intermediate transfer member is performed. An intermediate transfer system for obtaining a final image by transferring is already known. In particular, the intermediate transfer method is adopted as a superimposed transfer method of a toner image of each color in a full-color image forming apparatus that reproduces a color-separated original using subtractive color mixing using black, cyan, magenta, and yellow toners.

[0003] One of the "abnormal images" generated in the transfer process in the electrophotographic image forming apparatus is a "hollow phenomenon" in which a part of the toner image is not transferred. This phenomenon occurs in a general non-contact transfer method using corona discharge in a full-color image forming apparatus having a large total amount of adhered toner, but tends to easily occur in a contact transfer method using a bias roller or the like.

The cause of the "hollow-out phenomenon" is that in the case of a full-color image, the thickness of the toner layer is increased, and the bias roller uses mechanical pressure, which is a non-Coulomb force between the toner and the surface of the intermediate transfer member due to contact pressure. In the process of repeatedly performing the image forming process, a filming phenomenon in which the toner adheres to the surface of the toner image carrier in a film-like manner occurs in the step of repeatedly performing the image forming process, and a strong adhesion occurs between the surface and the toner. This is considered to be due to the generation of adhesion.

The following two techniques have already been disclosed as means for avoiding such a "hollow-out phenomenon". First technology: US Patent No. 5,053,827 (METHODO
AND APPARATUS FOR ATRANSFER BELT).

In this US patent, a roller (conditioning mean) made of a member made of a fluorine-based material having a surface energy smaller than the surface energy of an intermediate transfer belt as an intermediate transfer member is provided on the surface of the intermediate transfer belt. A technique having a conditioning process for reducing the surface energy on the intermediate transfer belt has been disclosed.

A technique similar to this is disclosed in Japanese Patent Laid-Open No. 2-198.
No. 476 is also disclosed. This publication discloses a technique in which the surface energy of the intermediate transfer body itself is reduced by adding a substance that reduces the wettability (that is, the surface energy is reduced) to the intermediate transfer body.

Second technique: JP-A-63-58387. This publication discloses a technique for reducing the “hollow-out phenomenon” at the time of transfer by making the linear velocity of the toner image support different from that of the transfer paper.

[0009] A similar technique is also disclosed in the following patent publication. JP-A-3-1486
No. 80, JP-A-6-83212, JP-A-6-83212
No. 317992.

This second technique is considered by the present inventor to be due to the "shearing force" acting on the toner.
In order to further obtain the effect, the invention has been completed in which the condition that the surface energy of the toner image carrier is equal to or less than the surface energy of the transfer material is added. However, the range in which the inventor has confirmed the effect is "transfer from an intermediate transfer member, which is a toner image carrier, to transfer paper, which is a transfer material", which is shown in the embodiment.

The inventor of the present invention discloses "transfer from a photosensitive member as a toner image bearing member to an intermediate transfer member as a transfer material" disclosed in Japanese Patent Application Laid-Open No. 6-317992 with the linear velocity of the photosensitive member fixed. Then, evaluation was made by changing the linear velocity of the intermediate transfer member, and the results shown in FIG. 3 were obtained. As is apparent from this figure, even if the linear velocity between the photosensitive member and the intermediate transfer member is set to a speed difference, the hollow rank does not change.
In addition to the effect described in JP-A-92-92, when a linear velocity difference between the photosensitive member and the intermediate transfer member is provided, a periodic deviation occurs in the main scanning direction. When this result was examined in detail, the line segment when the linear speed of the intermediate transfer member was changed based on the length of a certain line segment in the sub-scanning direction when the photosensitive member and the intermediate transfer member were at the same speed. The length ratio was found to show little change. This means that even when there is a linear velocity difference between the photosensitive member and the intermediate transfer member between the image shifts, they move at the same speed.

As a result of further study of this phenomenon, the inventor considered the occurrence of the following effects. This will be described with reference to FIG. 1. When a bias having a polarity opposite to that of the toner is applied to the intermediate transfer belt to transfer the toner from the photoreceptor onto the intermediate transfer belt, an "electrostatic attraction force" is generated between the photoreceptor and the intermediate transfer body by a transfer electrostatic field. (See FIG. 4A). 2. By setting the linear velocity of the intermediate transfer body to be higher than the linear velocity of the photoreceptor in this state, a "shear force" is generated between the two (see FIG. 4B). 3. However, if the "electrostatic attraction force" is larger than the "shearing force", the photoconductor is displaced so as to match the intermediate transfer member (see FIG. 4C). 4. The photoreceptor moves at the same speed as the intermediate transfer member up to the permissible displacement amount in the system, but when the permissible displacement amount is exceeded, the photoreceptor moves to cancel the displacement, causing a rapid linear velocity fluctuation (see FIG. 4 (d)).

[0013]

As described above, in the transfer from the photoconductor to the intermediate transfer member, the linear velocity between the photoconductor and the intermediate transfer member has a difference in order to reduce the "dropout phenomenon". Then, the above operations 1 to 4 are repeated. Then, at the time when the photosensitive member exceeds the permissible displacement amount during the operation of step 4, when the linear velocity fluctuates suddenly, there is a problem that a deviation appears on the image. That is, the displacement shown in FIG.
The image on the transfer material corresponding to the distortion release point is shown in FIG.
Image shift indicated by oblique lines appeared.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is intended to prevent an image shift caused by a shear force between an electrostatic attraction force and a shear force at the time of transfer from an image bearing member to an intermediate transfer member, and to eliminate hollow images It is an object of the present invention to provide an image forming apparatus that can solve the problem of transfer failure such as a phenomenon.

[0015]

In order to achieve the above object, an image carrier, an intermediate transfer body and a final transfer body are provided, and the image carrier, the intermediate transfer body, and the intermediate transfer body and the final transfer body are provided. An image forming apparatus that forms an electrostatic field on the image carrier and transfers the toner image formed on the image carrier to a final transfer body via an intermediate transfer body, wherein the toner image is transferred from the image carrier to the intermediate transfer body. During the primary transfer, the image carrier is removed so as to eliminate displacement and distortion caused by electrostatic attraction between the image carrier and the intermediate transfer body and shearing force between the image carrier and the intermediate transfer body. And the linear velocity of the intermediate transfer member are set.

In the present invention, the displacement and strain generated by the electrostatic attraction force between the image bearing member and the intermediate transfer member and the shear force between the image bearing member and the intermediate transfer member are reduced by the image bearing member. It is effective if the linear transfer speed of the intermediate transfer member is eliminated by making the linear transfer speed constant.

Further, in order to achieve the above object, the present invention comprises an image carrier, an intermediate transfer member, and a final transfer member, wherein the image carrier, the intermediate transfer member, and the intermediate transfer member are provided between the intermediate transfer member and the final transfer member. In an image forming apparatus in which an electrostatic field is formed and the toner image formed on the image carrier is transferred to a final transfer body via an intermediate transfer body, the toner image formed on the image carrier bears the image carrier. Primary transfer to the intermediate transfer body set to a linear velocity equal to the linear velocity of the body, and then secondary transfer to the final transfer body having a difference between the linear velocity of the intermediate transfer body and the linear velocity. Features.

Further, in order to achieve the above object,
A toner having an image carrier, an intermediate transfer body, and a final transfer body, forming an electrostatic field between the image carrier and the intermediate transfer body and between the intermediate transfer body and the final transfer body, and forming the toner on the image carrier. In an image forming apparatus in which an image is transferred to a final transfer member via an intermediate transfer member, the toner image formed on the image carrier is transferred to the intermediate transfer member at a linear speed equal to a linear speed of the image carrier. To the final transfer member provided with a linear speed and a linear speed difference of the intermediate transfer member, and a lubricant is applied to at least one surface of the image carrier and the intermediate transfer member. Is applied.

Further, the present invention is effective when a lubricant applying means is provided on the image bearing member and the intermediate transfer member. Furthermore, the present invention is effective when the lubricant application means provided on the image carrier applies a lubricant to the surface of the image carrier via a cleaning brush for cleaning the surface of the image carrier.

Further, the present invention is effective when the image carrier, the intermediate transfer member, and the final transfer member are driven by independent drive systems.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a color image forming apparatus using an intermediate transfer belt system according to the present invention, and FIG. 2 is an enlarged view around a photoconductor and an intermediate transfer belt of the color image forming apparatus. Hereinafter, the configuration and operation of the color image forming apparatus using the intermediate transfer belt system will be described with reference to FIGS.

A color image reading device (hereinafter, referred to as a color scanner) 1 irradiates an image of an original 3 with an irradiation lamp 4,
An image is formed on the color sensor 7 via the mirror group 5 (-1, 2, 3) and the lens 6, and the color information of the document 3 is converted into, for example, Blue, Green, Red (hereinafter, B, G,
R) (which is abbreviated as R) for each color separation light and converts it into an electrical image signal.

In this example, the color sensor 7 has B, G, R
And a photoelectric conversion element such as a CCD, and performs simultaneous reading of three colors. Then, based on the intensity levels of the B, G, and R color separation image signals obtained by the color scanner 1, a color conversion process is performed by an image processing unit (not shown), and Black, Cyan, Magenta, Y
The color image data of “ellow” (hereinafter abbreviated as Bk, C, M, Y) is obtained. This is performed by a color image forming apparatus (hereinafter, referred to as a color printer) 2 described below.
A visible image is formed on the photoreceptor 9 as a toner image carrier by using toners of respective colors Bk, C, M, and Y, and a final color image is obtained. The operation system of the color scanner 1 for obtaining the image data of Bk, C, M, and Y is a scanner start signal synchronized with the operation of the color printer 2, and the illumination / mirror optical system in FIG. The original is scanned in the direction of the arrow to obtain one color of image data for each scan.

Next, an 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 as an additional carrier. The writing optical unit 8
Are a laser light source (LD) 8-1 and its light emission drive control unit (not shown), a polygon mirror 8-2 and its rotation motor 8-3, an f / θ lens 8-4, and a reflection mirror 8-5.
And so on.

The photosensitive drum 9 rotates counterclockwise as indicated by the arrow in the figure. Around the photosensitive drum cleaning unit (including a pre-cleaning neutralizer) 10, a neutralizing lamp 11, a charger 12, Potential sensor 13, Bk developing device 14, C developing device 15, M developing device 16, Y developing device 1
7, development density pattern detector 18, intermediate transfer belt 19
And so on.

Each of the developing units 14, 15, 16 and 17 has a developing sleeve 14-1 and 15- which rotates by bringing an ear of developer into contact with the surface of the photosensitive drum 9 in order to develop an electrostatic latent image.
1, 16-1, 17-1 and developing paddles 14-2, 15-2, 16- which rotate to pump up and agitate the developer.
2, 17-2, and toner concentration detection sensors 14-3, 15-3, 16-3, and 1 for detecting the toner concentration of the developer.
7-3 and the like.

In the standby state, the four developing units 14, 1
In all of 5, 16, and 17, the agent on the developing sleeve is in a cutting state (development inoperative state), but in the following description, the order of the developing operation (color image forming order) is Bk,
An example of C, M, and Y will be described (however, the image forming order is not limited to this).

When the copying operation is started, reading of the Bk development data is started at a predetermined timing by the color scanner 1, and optical writing / latent image formation by the laser light from the writing optical unit 8 is started based on the image data. Then, an electrostatic latent image based on the Bk image data is formed on the photosensitive drum 9 (hereinafter, the electrostatic latent image based on the Bk image data will be referred to as a Bk latent image. Image, M latent image, and Y latent image).

In order to enable development from the leading end of the Bk latent image, the developing sleeve 14-1 is rotated before the leading end of the latent image reaches the developing position of the Bk developing unit 14 to spike the agent. The Bk latent image is developed with Bk toner. And thereafter
The developing operation of the Bk latent image area is continued, but immediately after the rear end of the latent image has passed the Bk developing position, the Bk developing sleeve 14
-1 is carried out and the development is inoperative. This is completed at least before the leading end of the C latent image based on the next C image data arrives.

The rotation is performed by switching the direction of rotation of the ear-cut developing sleeve 14-1 in a direction opposite to that during the developing operation.
The Bk toner image formed on the photosensitive drum 9 is transferred by electrostatic force to the surface of an intermediate transfer belt 19 which is an intermediate transfer member as a toner image carrier driven in the same direction as the photosensitive drum 9. (Hereinafter, the transfer of the toner image from the photosensitive drum 9 to the intermediate transfer belt 19 is referred to as belt transfer).

This belt transfer is performed by applying a predetermined bias power to the transfer bias roller 20 in a state where the photosensitive drum 9 and the intermediate transfer belt 19 are in contact with each other. The Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 9 are sequentially aligned on the same surface of the intermediate transfer belt 19 to form a four-color superimposed belt transfer image.
Thereafter, batch transfer is performed on transfer paper.

The structure and operation of the transfer belt unit will be described later. By the way, on the photosensitive drum 9 side, the Bk toner image formed in the Bk process is transferred to the intermediate transfer belt 1.
After the transfer to C9, cleaning and static elimination are performed.
Although the process proceeds, reading of the C image data by the color scanner 1 starts at a predetermined timing, and a C latent image is formed on the photosensitive drum 9 by laser light writing of the writing optical unit 9 based on the image data.

The C developing device 15 starts rotating the developing sleeve 15-1 with respect to the developing position after the trailing end of the preceding Bk latent image has passed and before the leading end of the C latent image has arrived. Then, the C latent image is developed with C toner. Thereafter, the development of the C latent image area is continued, but when the rear end of the latent image passes, the C developing sleeve 15-1 is used in the same manner as in the case of the Bk developing device.
Perform the top cutting. This is also completed before the leading end of the next M latent image arrives.

The operations of reading image data, forming a latent image, and developing the M and Y processes are the same as those of Bk and C described above, and a description thereof will be omitted. Next, the intermediate belt unit will be described.

The intermediate transfer belt 19 includes a driving roller 21,
It is stretched around the belt transfer bias roller 20 and the driven roller group, and is driven and controlled by a drive motor (not shown) as described later. Belt cleaning unit 22
Is constituted by an inlet seal 22-1, a rubber blade 11-2, a belt contacting / separating mechanism 22-3, and the like.
While the second, third, and fourth colors after the Bk image of the color are transferred to the belt, the contact and separation mechanism 22-3 separates the Bk image from the belt surface.

A transfer unit 23 for transferring an image on the intermediate transfer belt 19 to transfer paper 24 is disposed at a position facing the drive roller 21 of the intermediate transfer belt 19, and the transfer unit 23 Transfer bias roller 23-1, roller cleaning blade 23-2, and intermediate transfer belt 19, which are contact transfer members as applying means
, And a contact / separation mechanism 23-3. The transfer bias roller 23-1 of the transfer unit 23 is normally separated from the surface of the intermediate transfer belt 19 by the contact / separation mechanism 23-3. 24, the roller 23-1 is pressed by the contact / separation mechanism 23-3 at a certain timing.
Is transferred to the transfer paper 24 by applying a predetermined bias voltage to the transfer paper 24.

The transfer paper 24 is fed from a transfer paper cassette (for example, transfer paper cassette (A) 30) selected from the plurality of transfer paper cassettes 30, 31, 33 by a paper feed roller (25). Then, the sheet is fed to the transfer position by the registration roller 26 at the timing when the leading end of the four-color superimposed image on the surface of the intermediate transfer belt 19 reaches the transfer position.

The following method is used to move the intermediate transfer belt 19 depending on the image forming mode. (1) Constant speed forward system. This operation is performed in the image forming mode of only the uniform color such as Bk toner, and the forward movement continues at a constant speed as it is after the belt transfer of the first toner image.

The transfer bias roller 23-1 is brought into contact with the intermediate transfer belt 19 by the contact / separation mechanism 23-3 in timing with the transfer paper 24 fed in timing with the leading end of the first toner image. Then, the toner image is transferred to the transfer paper 24.

Thereafter, the toner images formed in accordance with the number of repeats and transferred onto the intermediate transfer belt 19 are respectively transferred to transfer paper 24. (2) Reciprocating (quick return) method. This operation is performed in an image forming mode for forming an image with two or more colors of toner. When the belt transfer of the Bk toner image is completed, the intermediate transfer belt 19 is separated from the surface of the photosensitive drum 9 and the forward movement is performed. At the same time, a fast return is made in the reverse direction. Return is intermediate transfer belt 1
After the image leading end positions on the nine surfaces have passed the belt transfer equivalent position in the reverse direction, and further moved by a predetermined distance, they are stopped and brought into a standby state.

Next, when the leading end of the C toner image on the surface of the photosensitive drum 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is started again in the forward movement direction. Further, the intermediate transfer belt 19 is brought into contact with the surface of the photosensitive drum 9 again. Also in this case, the C image is transferred to the intermediate transfer belt 19.
The belt transfer is performed under the condition that the Bk image is accurately overlapped on the surface.

Thereafter, the same operation is performed to proceed to the M and Y image processes, and a belt transfer image of four-color superposition is obtained. And 4
Following the belt transfer process of the Y image of the color, the transfer bias roller 23 moves forward at the same speed without returning to transfer the four-color superimposed toner image on the surface of the intermediate transfer belt 19 onto the transfer paper 24 at a time. Reference numeral 1 designates an intermediate transfer belt 1 by a contact / separation mechanism 23-3 in synchronization with transfer paper 24 fed in synchronization with the leading end of the toner image.
9, the toner image is transferred to the transfer paper 24.

The transfer paper 24 on which the toner image has been transferred from the surface of the intermediate transfer belt 19 is conveyed to a fixing device 28 by a paper conveying unit 27, controlled at a predetermined temperature, and coated with silicone oil as a release agent. Fixing roller 28
-1 and the pressure roller 28-2 fuse and fix the toner image on the transfer paper. Then, the transfer paper after fixing is discharged to the copy tray 29, and a final copy image is obtained.

Each time an image of each color is formed on the photosensitive drum 9, the photosensitive drum 9 after the belt transfer of the toner image is removed from the photosensitive drum cleaning unit 10 (the static eliminator 1 before cleaning).
0-1, brush roller 10-2, rubber blade 10-
The surface is cleaned in 3), and the charge is uniformly removed by the charge removing lamp 11. Further, after the toner image is transferred onto the transfer paper 24, the cleaning unit 2 is attached to the intermediate transfer belt 19.
2 is pressed by the contact / separation mechanism 22-3, and the belt surface is cleaned.

At the time of repeat copying, the operation of the color scanner 1 and the image formation on the photosensitive drum 9 are performed at a predetermined timing following the first Y (fourth color) image process at the second sheet Bk (1). Go to the image process. Further, the intermediate transfer belt 19 is a transfer paper 24 for the first four-color image.
Subsequent to the batch transfer process, the second Bk toner image is belt-transferred to the area whose surface has been cleaned by the cleaning unit 22. After that, the operation is the same as that of the first sheet.

The transfer paper cassettes 30, 31, 32, 3
Transfer papers 3 of various sizes are stored, and are fed and conveyed toward the registration rollers 26 at a timing from a storage cassette of the size paper designated by an operation panel (not shown). Reference numeral 34 denotes a manual paper feed tray used for feeding overhead projector (OHP) paper or thick paper.

The copy mode for obtaining a four-color full-color image has been described above. However, in the case of the three-color copy mode or the two-color copy mode, the same as the above for the designated colors and the number of times. Operation will be performed.

In the case of the single-color copy mode, until the predetermined number of sheets is completed, only the developing device of that color is set in the developing operation (spike), and the intermediate transfer belt 19 is placed on the surface of the photosensitive drum 9. The belt cleaning unit 22 is driven at a constant speed in the forward movement direction while being in contact with the intermediate transfer belt 1.
The copy operation is performed in a state in which the touch panel 9 is kept in contact.

Here, specific examples of the main configuration and image forming conditions of the image forming apparatus in this embodiment will be described below. -Photoconductor drum: OPC. -Intermediate transfer belt: carbon-dispersed fluorine resin ETF
E (ethylene / tetrafluoro / ethylene), volume resistivity 10 ¹⁰ Ωcm, surface resistivity 10 ⁹ Ωcm ² .・ Transfer bias roller: Hydrin rubber roller coated with PFE tube, volume resistivity 10 ⁹ Ωcm.・ Toner: Black (B) with polyol as main resin
k) is carbon, cyan (C), magenta (M), and yellow (Y) are colored with each pigment.

Externally added silica as a fluidity imparting material. -Developer characteristics: toner density; 4 to 6 (wt%) for each color, toner charge amount: each to -15 to -25 (C / g). -Photoconductor potential: Image part (LD data "255" part) -80 to -130
(V), non-image part (LD data "0" part) -500 to -700
(V), process speed: 180 mm / _sec , belt transfer bias voltage: 1C: 1200 (v), 2C: 1300 (v), 3C: 1400 (v), 4C: 1500 (v), transfer bias voltage 1300 (v).

As described above, the structure of the image forming apparatus according to the present invention
The operation has been described. By the way, it is well known that the "hollow phenomenon" in the image forming apparatus occurs in the transfer process as described above. In order to solve this problem, the transfer material is conveyed under such a condition that a shear force is generated between the toner image carrier and the transfer material at the time of transfer. One of the specific methods is to carry the toner image. To provide a speed difference between the body and the transfer material.

However, if a linear velocity difference is provided between the photosensitive drum 9 as a toner image carrier and the intermediate transfer belt 19 as a transfer material, as described above, periodic image shift occurs. Admitted. It was also recognized that this periodic image shift tended to become shorter as the linear velocity ratio between the photosensitive drum 9 and the intermediate transfer belt 19 became larger.

The present inventors have considered the reason as follows. As described above, the mechanism of the occurrence of the periodic image shift is that the electrostatic attraction force between the photosensitive drum 9 and the intermediate transfer belt 19 generated by the electrostatic transfer electric field is applied to the intermediate transfer belt 19 as an electrode. This is due to the fact that the body drum 9 is in direct contact with the body drum and the shear force is larger than the linear velocity. As a result, at least one of the photosensitive drum 9 and the intermediate transfer belt 19 is displaced by the electrostatic attraction force, and moves at the same linear speed until the displacement exceeds the allowable displacement. However, when the displacement exceeds the allowable amount, the displacement is released, so that a sudden speed fluctuation occurs, resulting in an image shift as shown in FIG. The magnitude of the linear speed ratio depends on the photosensitive drum 9 or the intermediate transfer belt 1.
9 determines the amount of displacement per unit time. Therefore, when the linear velocity ratio is small, the amount of displacement per unit time is also small, and the time until the displacement reaches the allowable amount becomes long. On the other hand, when the linear velocity ratio is large, the amount of displacement is large, and the time required for the displacement to reach the allowable amount is shortened.

Further, by providing a linear velocity difference between the intermediate transfer belt 19 and the transfer material, no image displacement occurred and the improvement of the "hollow-out phenomenon" was recognized. This is because, even in the secondary transfer, an electrostatic attraction force due to an electrostatic field is generated between the intermediate transfer belt 19 and the transfer material, but by interposing the transfer material,
From the fact that the electrostatic attraction force itself is smaller than the shearing force and the structural characteristics of the transfer material, it is considered that the state of "always slipping" can be maintained.

As described above, even if the period of the image shift changes depending on the magnitude of the linear velocity ratio, the image shift is a position shift of each color in the full-color image forming apparatus. The displacement due to the difference in linear speed between the body drum 9 and the intermediate transfer belt 19 should not occur, and therefore, the linear speed between the photosensitive drum 9 and the intermediate transfer belt 19 is the same.

With this configuration, since there is no linear velocity difference between the photosensitive drum 9 and the intermediate transfer belt 19, the photosensitive drum 9 or the intermediate transfer belt 19 is not displaced, and the above-described image shift is prevented. can do. Further, by providing a linear velocity difference between the intermediate transfer belt 19 and the transfer material, it is possible to prevent the occurrence of the “hollow-out phenomenon”.

In order to achieve the above configuration, it is necessary to drive each of the photosensitive drum 9 and the intermediate transfer belt 19 with high precision. This can be achieved to some extent by using expensive drive trains or speed control means.
High-end machines that require high precision can be implemented as they are,
Even if an inexpensive device is designed for the same speed, a linear speed ratio will occur due to the tolerance of each component. further,
Even when the photosensitive drum 9 and the intermediate transfer belt 19 are driven by independent driving sources, variations in the driving sources are added as factors, and there is a great risk that driving at the same speed is difficult and a linear speed ratio is generated. These consequently result in long-period image shifts.

This image deviation is released when the displacement / distortion exceeds the allowable value. As a result, the larger the allowable value is, the larger the displacement / distortion amount is, and the larger the speed fluctuation when releasing is. Therefore, by reducing the allowable value, release should occur at a point in time when displacement and distortion are slight, and speed fluctuations should also be reduced. It can be seen that this state can be realized by making the photosensitive drum 9 and the intermediate transfer belt 19 slippery.

Therefore, in the present embodiment, the photosensitive drum 9
A lubricant may be applied to at least one of the intermediate transfer belt 19 and the intermediate transfer belt 19. In this case, the lubricant is applied to the photoconductor drum 9 by applying a lubricant, for example, zinc stearate, which is arranged to be in contact with the brush roller 10-2 of the photoconductor cleaning unit 10, to the photoconductor drum 9. I have to.

For applying lubricant to the intermediate transfer belt 19, a coating device 36 is provided as shown in FIGS.
The coating device 36 is composed of a brush 38 that melts a lubricating oil additive containing zinc stearate as a main component as a lubricant, and cools and solidifies the lubricant 37 to rub the surface of the lubricant 37. I have. Here, the reason why zinc stearate was selected as the lubricant is that it is easy to mold and manufacture, and that it has no adverse effect on the intermediate transfer belt 19 related to image formation. Therefore, zinc stearate is not the only substance according to the present invention,
Other substances may be used as long as they have such characteristics.

When the lubricant is applied to both the photosensitive drum 9 and the intermediate transfer belt 19, a very short-period image shift of a level that hardly appears on the image is generated as shown in FIG. It was proved that the consideration was correct. In addition, it is effective to apply the lubricant to only one of the photosensitive drum 9 and the intermediate transfer belt 19. Further, in the above description, the embodiment in which the transfer unit is a roller has been described. However, it is already known that the transfer unit may be in the form of a belt or a drum in addition to the roller.

In this embodiment, the toner image carrier is an intermediate transfer belt, and the transfer material is transfer paper. However, the relationship is not limited to this combination. For example, the photosensitive drum 9 and the intermediate transfer member may be used. The object of the present invention can be achieved even by a combination with the above.

[0063]

As described above, according to the present invention,
Eliminates displacement and distortion between the image carrier and the intermediate transfer member due to electrostatic attraction, prevents image displacement due to speed fluctuations that occur when displacement and distortion are released, and eliminates problems with poor transfer such as the "hollow-out phenomenon" An image forming apparatus capable of performing the above-described operations can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color image forming apparatus using an intermediate transfer belt system according to the present invention.

FIG. 2 is an enlarged view around a photoconductor and an intermediate transfer belt of the color image forming apparatus shown in FIG. 1;

FIG. 3 is a diagram illustrating a relationship between a linear speed ratio between a photoconductor and an intermediate transfer belt and a hollow rank;

FIG. 4 is an explanatory diagram of a model of occurrence of image shift due to a linear speed difference between a photosensitive member and an intermediate transfer belt.

FIG. 5 is an explanatory diagram showing a relationship between a displacement / distortion amount and an image shift.

FIG. 6 is an explanatory diagram showing a relationship between a displacement / distortion amount at the time of applying a lubricant and an image shift.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Color image reading device (color scanner) 2 Color image recording device (color printer) 3 Original 9 Photoconductor drum 10 Photoconductor cleaning unit 10-2 Brush roller 14 Black (Bk) developing device 15 Cyan (C) developing device 16 Magenta (M) Developing device 17 Yellow (Y) developing device 19 Intermediate transfer belt 20 Belt transfer bias roller 21 Belt drive roller 23 Transfer unit 23-1 Transfer bias roller 24 Transfer paper 36 Coating device 37 Lubricant 38 Brush

Claims (7)

[Claims] 1. An image carrier comprising an image carrier, an intermediate transfer member, and a final transfer member, wherein an electrostatic field is formed between the image carrier, the intermediate transfer member, and the intermediate transfer member and the final transfer member. An image forming apparatus for transferring the toner image formed on the intermediate transfer member to a final transfer member via an intermediate transfer member, wherein the primary transfer is performed to transfer the toner image from the image bearing member to the intermediate transfer member. The linear velocities of the image carrier and the intermediate transfer member were set so as to eliminate the displacement and strain caused by the electrostatic attraction force between the transfer members and the shear force between the image carrier and the intermediate transfer member. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein a displacement generated by an electrostatic attraction force between said image bearing member and said intermediate transfer member and a shear force between said image bearing member and said intermediate transfer member. -An image forming apparatus characterized in that distortion is eliminated by making the linear speed between the image carrier and the intermediate transfer member uniform. 3. An image carrier comprising an image carrier, an intermediate transfer member, and a final transfer member, wherein an electrostatic field is formed between the image carrier, the intermediate transfer member, and the intermediate transfer member and the final transfer member. In an image forming apparatus in which a toner image formed on a body is transferred to a final transfer body via an intermediate transfer body, the toner image formed on the image carrier has a linear velocity equal to the linear velocity of the image carrier. An image forming apparatus, wherein primary transfer is performed on the set intermediate transfer member, and then secondary transfer is performed on the final transfer member having a linear speed and a linear speed difference of the intermediate transfer member. 4. An image carrier comprising an image carrier, an intermediate transfer member, and a final transfer member, wherein an electrostatic field is formed between the image carrier, the intermediate transfer member, and the intermediate transfer member and the final transfer member. In the image forming apparatus, the toner image formed on the image carrier is set to a linear speed equal to the linear speed of the image carrier. Primary transfer to the intermediate transfer body, and then secondary transfer to the final transfer body provided with a linear velocity and a linear velocity difference of the intermediate transfer body, and at least one of the image carrier and the intermediate transfer body An image forming apparatus, characterized in that a lubricant is applied to a surface of the image forming apparatus. 5. The image forming apparatus according to claim 4, wherein a lubricant applying unit is provided on the image carrier and the intermediate transfer body. 6. The image forming apparatus according to claim 4, wherein the lubricant applying means provided on the image carrier applies a lubricant via a cleaning brush for cleaning the surface of the image carrier. An image forming apparatus, which is applied to an image forming apparatus. 7. The image forming apparatus according to claim 4, wherein the image carrier, the intermediate transfer member, and the final transfer member are driven by independent drive systems. Image forming apparatus.