JP2003263069A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of forming an image excellent in density, sharpness, etc. <P>SOLUTION: A lubricant is applied to an image forming body and an addition agent comprising the lubricant is added to toner. A patch image is formed on the image forming body or an image forming body. An amount that the lubricant is applied is controlled based upon a detected amount that the toner is attached to the patch image after transfer. <P>COPYRIGHT: (C)2003,JPO

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 for forming an image by an electrophotographic method, and more particularly to a transfer technique using a transfer roller.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image by an electrophotographic method, a charger using a corona discharge is used as a transfer technique for transferring a toner image from an image forming member such as a photosensitive member to a transfer material or the like. In addition, a transfer technique using a transfer roller is widely used.

[0003]

A transfer technique using a transfer roller has advantages such as a high transfer rate and little image disturbance in a transfer portion, and forms a high quality image such as a color image. It is used when required.

While the transfer using the transfer roller has such advantages, it has the following problems. (1) The transfer roller may not be transferred as a lump due to the pressure of the toner image, which may cause a phenomenon called transfer omission. In particular, in a solid image having a large amount of toner, a transfer omission may occur, and a phenomenon referred to as a hollow image may occur in which a non-transferred portion occurs in the central portion of the solid image.

A lubricant such as a fatty acid metal salt has been applied as a means for preventing hollow defects. However, depending on the application of the lubricant, the hollow defect can be prevented to some extent, but there is a problem that toner filming occurs and the background stain and the density decrease easily occur. (2) In an image forming apparatus using an intermediate transfer body, there is a means for providing an elastic layer on the intermediate transfer body as a means for preventing a hollow portion. Such preventive means has an effect of preventing a hollow image at the initial stage, but the elastic layer becomes fatigued due to long-term use and the effect of preventing the hollow image is lowered, and the positional accuracy of the image is lowered, so that a color image forming operation is performed. There is a problem such as causing color shift in. As another means for preventing inner voids, there is a means to set the pressure of the transfer roller low. However, when this means is adopted, the stability of the nip in the transfer part is reduced, and image scattering and insufficient transfer occur. There is a problem of doing.

[0006] Still another means for preventing the hollow portion is to apply a lubricant. Although the application of the lubricant is effective in preventing the hollow portion, there is a problem that the uneven coating of the lubricant occurs to cause the hollow portion. (3) The hollow void phenomenon can be prevented to some extent by appropriately selecting the resistance value of the intermediate transfer member. However, due to the thickness of the intermediate transfer member, in addition to the electric field in the thickness direction of the intermediate transfer member, There is a problem that the electric field affects the transfer. It can be said that the voids are caused by the influence of the toner image on the transfer electric field, but the voids are more likely to occur due to the increase in the thickness of the intermediate transfer member. Particularly, in color image formation, the above-mentioned (2) In addition to the problem, there is a transfer problem when a toner image of each color is transferred to an intermediate transfer member and a toner image of each color is overlaid to form a full-color toner image.

That is, in the transfer step of transferring and superimposing the toner image of the second color on the intermediate transfer member on which the toner image of the first color is formed, the transfer rate and the first transfer rate at the portion where the toner image of the first color exists. The problem is that there is a difference in the transfer rate in the portion where the color toner image does not exist. In particular, when the toner image of the first color is a solid image, the transfer electric field is lowered and the hollow image is likely to occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can solve the above problems in transferring a toner image using a transfer roller and can form an image excellent in terms of density, sharpness and the like. And

[0009]

The above-mentioned object of the present invention is achieved by the following invention.

(1) An image forming body, a latent image forming means, a developing means, a transfer means for transferring a toner image from the image forming body to a transfer material by a transfer roller, and a lubricant application for applying a lubricant to the image forming body. In the image forming apparatus having a means, the developing means performs development using a toner containing 0.01 to 2 mass% of an external additive made of a lubricant.

(2) An image forming body, a latent image forming means, a developing means, an intermediate transfer body, and a primary transfer means for transferring a toner image from the image forming body to the intermediate transfer body by a primary transfer roller,
An image forming apparatus having a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material and a lubricant applying means for applying a lubricant to at least one of the image forming body and the intermediate transfer body. Is an image forming apparatus in which development is performed using a toner containing 0.01 to 2% by mass of an external additive made of a lubricant.

(3) Image forming body, latent image forming means, developing means, transfer means for transferring a toner image from the image forming body to a transfer material by a transfer roller, and lubricant application for applying a lubricant to the image forming body. An image forming apparatus having means, which has a detection means for detecting the toner adhesion amount on the image forming body and a control means for controlling the lubricant application means based on the output of the detection means. Forming equipment.

(4) Image forming body, latent image forming means, developing means, intermediate transfer body, primary transfer roller, primary transfer means for transferring the toner image from the image forming body to a transfer material, and secondary transfer roller. An image forming apparatus comprising: a secondary transfer unit that transfers a toner image from the intermediate transfer member to a transfer material; and a lubricant applying unit that applies a lubricant to at least one of the image forming member and the intermediate transfer member. A first detection unit that detects the amount of toner adhered to the formed body, and a first control unit that controls the lubricant application unit based on the output of the first detection unit.
An image forming apparatus having a control unit.

(5) Image forming body, latent image forming means, developing means, intermediate transfer body, primary transfer roller, primary transfer means for transferring the toner image from the image forming body to a transfer material, and secondary transfer roller. In the image forming apparatus, a secondary transfer unit that transfers a toner image from the intermediate transfer member to a transfer material and a lubricant applying unit that applies a lubricant to at least one of the image forming member and the intermediate transfer member are provided. An image forming apparatus comprising: a second detection unit that detects the amount of toner adhering to the transfer member; and a second control unit that controls the lubricant application unit based on the output of the second detection unit.

(6) Image forming body, latent image forming means, developing means, intermediate transfer body, primary transfer means for transferring a toner image from the image forming body to the intermediate transfer body by the primary transfer roller, the intermediate transfer body In an image forming apparatus having secondary transfer means for transferring a toner image from a transfer material to a transfer material and lubricant applying means for applying a lubricant to the image forming body, the intermediate transfer body is an endless belt having a thickness of 70 μm or less. An image forming apparatus comprising:

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <Image Forming Apparatus> FIG. 1 shows an example of a monochrome image forming apparatus which is an image forming apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a photoconductor as an image forming body.

The photoreceptor 1 as an image forming body includes an organic photoreceptor having a photosensitive layer in which an organic photoconductor is dispersed in a resin, a-
A Si photoconductor or the like is used.

Reference numeral 2 is a charging means for charging the photoconductor 1 and forming a uniform potential on the photoconductor 1. As charging means,
A contact charging type charging means using a scorotron charger having a control grid and a discharge electrode or a roller to which a voltage is applied is used.

Reference numeral 3 is an exposing means for exposing the photosensitive member 1 according to image data. As the exposing means, a scanning exposing means having a laser diode as a light source and a scanning optical system including a polygon mirror, a lens and a mirror, and a scanning optical means having a light emitting diode array and an image forming optical fiber are used. The exposure unit 3 performs dot exposure on the photoconductor 1 according to the image data. The charging unit 2 and the exposing unit 3 form a latent image forming unit.

Reference numeral 4 denotes a developing means, which is a developing means for developing with a one-component developer or a two-component developer. In the examples described below, a two-component developer is used. The developer is conveyed to the developing area by the developing sleeve 41 as the developer conveying means to develop the electrostatic latent image on the photoconductor 1 to form a toner image on the photoconductor 1. To the developing sleeve 41, a DC developing bias having the same polarity as the charging polarity of the charging unit 2 or a developing bias in which a DC voltage having the same polarity as the charging polarity of the charging unit 2 is superimposed on an AC voltage is applied, and exposure by the exposing unit 3 is performed. Reversal development is performed in which toner is attached to the portions. The toner consumed by the development is replenished from the toner replenishing means 42.

Reference numeral 5 is a transfer means including a transfer roller 51 and a transfer power source 52. The transfer unit 5 applies a transfer voltage having a polarity opposite to that of the toner on the photoconductor 1 to the back surface of the transfer material P to transfer the toner image to the transfer material P. Transfer roller 51
Is a roller having a conductive elastic layer formed on a metal shaft. As a material forming the elastic layer, rubber, sponge-like rubber or the like is used.

Reference numeral 6 denotes a separating means composed of a corona charger, which performs AC corona charging on the transfer material P to remove the charge from the transfer material P and separate it from the photoreceptor 1.

A fixing unit 7 fixes the toner image on the transfer material P by a heating roller 71 containing a heat source such as a halogen lamp and a pressure roller 72 in pressure contact with the heating roller 71.

Reference numeral 8 is a cleaning means. Untransferred toner and untransferred toner are attached to the photoconductor 1 after the transfer, and the photoconductor 1 needs to be cleaned in order to perform the next image formation. In the cleaning unit 8, the cleaning blade 81 made of an elastic blade such as urethane rubber removes the adhering substances on the photoconductor.

Reference numeral 9 denotes a lubricant applying means, which is a lubricant supplying body 91 and a lubricant supplying body 9 made of a molded lump of lubricant.
It consists of a brush 92 that contacts 1. By the rotation of the brush 92, the lubricant is scraped off little by little from the lubricant supply body 91 and applied to the photoconductor 1.

An electrostatic latent image is formed on the photosensitive member by the charging by the charging unit 2 and the image exposure by the exposing unit 3 in accordance with the rotation of the photosensitive member 1 indicated by the arrow. The formed electrostatic latent image is developed by the developing unit 4 to form a toner image on the photoconductor 1, and the formed toner image is transferred to the transfer material P by the transfer unit 5. The transfer material P on which the toner image is formed is fixed by the fixing means 7. The photoconductor 1 after the transfer material is separated is cleaned by the cleaning unit 8 and can be used for the next image formation. The toner consumed by the image formation is replenished from the toner replenishing means 42.

PS is a sensor as a detecting means for detecting the amount of toner forming the toner image on the photosensitive member 1.

FIG. 2 shows a color image forming apparatus according to an embodiment of the present invention. A semi-conductive endless belt-shaped intermediate transfer member that is rotatably and rotatably supported by a plurality of rollers 7 and 7A facing a plurality of sets of image forming units 10Y, 10M, 10C, and 10K arranged in tandem. 20 are arranged. Image forming unit 10Y that forms a yellow image
Has a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, a primary transfer unit 5Y, and a cleaning unit 6Y, which are arranged around a photoconductor 1Y as an image forming body. The image forming unit 10M that forms a magenta image has a photoreceptor 1M as an image forming body, a charging unit 2M, an exposing unit 3M, a developing unit 4M, a primary transfer unit 5M, and a cleaning unit 6M. The image forming unit 10C that forms a cyan image,
It has a photoreceptor 1C as an image forming body, a charging means 2C, an exposing means 3C, a developing means 4C, a primary transfer means 5C and a cleaning means 6C. Further, the image forming unit 10K that forms a black image includes a photoconductor 1K as an image forming body, a charging unit 2K, an exposing unit 3K, a developing unit 4K, and a primary transfer unit 5.
K and cleaning means 6K. The charging means 2Y and the exposing means 3Y, the charging means 2M and the exposing means 3M, the charging means 2C and the exposing means 3C, and the charging means 2K and the exposing means 3K respectively constitute latent image forming means.

Image forming units 10Y, 10M, 10C, 10
K is a lubricant applying means 9Y, 9M, 9C, 9K, respectively.
Is provided. Lubricant applying means 9Y, 9M, 9C, 9K
As shown in FIG. 3A, each of the
And a brush 92 that contacts the lubricant supply body 91,
By the rotation of the brush 92, the lubricant is scraped off little by little from the lubricant supply body 91 and applied to the photoconductor 1 and the intermediate transfer body 20. In FIG. 3, the lubricant applying means 9Y,
9M, 9C and 9K are indicated by reference numeral 9.

The paper feed cassette 30 stores the transfer material P.
The paper feeding unit including the paper feeding unit 21, the transportation rollers 22 </ b> A to 22 </ b> D, and the registration rollers 23 transports the transfer material P from the paper feeding cassette 20 to a position where an image is formed and transports it. Further, the fixing unit 24 is a device that thermally fixes to the transfer material P having a toner image, and the transfer material P that has been subjected to the fixing processing is ejected to the paper ejection tray 26 by the paper ejection roller 25.

In the image forming process, the image forming section 10
In Y, 10M, 10C, and 10K, the single-color toner images formed on the photoconductors 1Y, 1M, 1C, and 1K by charging, exposing, and developing are transferred to the primary transfer units 5Y, 5M, and 5K.
By C and 5K, they are sequentially transferred onto the intermediate transfer member 20 that moves in a circulating manner, and are combined to form a full-color toner image.

The transfer material P contained in the paper feed cassette 30.
Is fed by the paper feeding unit 21, is conveyed to the secondary transfer means 5A via the plurality of conveying roller rollers 22A, 22B, 22C, 22D and the registration roller 23, and the full color toner image is collectively transferred onto the transfer material P. To be done.

Transfer material P on which a full-color toner image has been transferred
Is subjected to a fixing process by the fixing unit 8, is sandwiched by the paper discharge rollers 24, and is discharged to the paper discharge tray 26 outside the machine.

On the other hand, after the color image is transferred onto the transfer material P by the secondary transfer means 5A, the intermediate transfer body 20 from which the transfer material P has been separated is cleaned by the cleaning means 6A.

<Embodiment 1 (Embodiment of the First Invention)> The first invention is implemented in the image forming apparatus of FIG.

The first embodiment will be described below with reference to the example of the image forming apparatus shown in FIG. 1, but the present invention is not limited to the illustrated example.

The first aspect of the present invention is to apply a lubricant to the image forming body, the latent image forming means, the developing means, the transfer means for transferring the toner image from the image forming body to the transfer material by the transfer roller, and the image forming body. In the image forming apparatus having the lubricant applying means, a toner containing 0.01 to 2 mass% of an external additive made of a lubricant is used in the developing means.

In the transfer process using the transfer roller,
There is a case where a toner image is pressed by the transfer roller into a lump and is not transferred, and a phenomenon referred to as transfer omission occurs.
In particular, in a solid image having a large amount of toner, a transfer omission may occur, and a phenomenon referred to as a hollow image may occur in which a non-transferred portion occurs in the central portion of the solid image.

A lubricant such as a fatty acid metal salt is applied as a means for preventing hollowing. However, depending on the application of the lubricant, the hollow defect can be prevented to some extent, but there is a problem that toner filming occurs and the background stain and the density decrease easily occur. The first aspect of the present invention solves such a problem. The first aspect of the present invention can prevent a hollow image from being satisfactorily achieved, and can prevent a background stain and a decrease in density due to toner filming, and can provide a clear and high density. An image is obtained.

The lubricant comprises a fatty acid metal salt, and specific examples of the lubricant include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, and other stearic acid metal salts, zinc oleate, manganese oleate, and the like. Metal oleate such as iron oleate, copper oleate, magnesium oleate, zinc palmitate,
Examples thereof include metal palmitate salts such as copper palmitate and magnesium palmitate, metal linoleate salts such as zinc linoleate and zinc linoleate, and metal ricinoleate salts such as zinc ricinoleate and lithium ricinoleate. Zinc stearate is particularly preferred.

The external additive is a property improving agent added to the toner after the toner particles are formed in the toner manufacturing process, and a lubricant is used in the present invention.

Lubricant is 0.0 based on toner mass.
By adding 1 to 2% by mass, hollow defects and toner filming are prevented, but when the lubricant is contained in an amount of less than 0.01% by mass or when no lubricant is added, toner filming is performed. Is likely to occur.

The preferred conditions in the present invention are as follows. (1) It is preferable that the lubricant applying unit 9 includes a lubricant supply body 91 and a brush 92 that contacts the lubricant supply body 91 and applies the lubricant to the photoconductor 1.

The lubricant supply body 91 is composed of a block of lubricant formed in a block shape. Further, the brush 92 comes into contact with the lubricant supply body 91 and the photoconductor 1 and rotates to apply the lubricant to the photoconductor 1 little by little.

FIG. 3A shows details of the lubricant applying means 9. In FIG. 3A, 1 is a photoreceptor as an image forming body, 92 is a brush composed of a shaft BSX and brush fibers flocked on the shaft BSX, and 91 is a lubricant supply composed of a mass of lubricant. It is the body. The lubricant supply body 91 is held by the holder 93, and the brush 95 is held at a predetermined pressure by the spring 95.
Pressed to 2.

The motor M1 makes contact with the brush 92, which rotates as shown by arrow W2, with respect to the photosensitive member 1 moving as shown by arrow W1, whereby the lubricant is uniformly applied to the photosensitive member 1 little by little. . The mounting position of the brush 92 is set so that the biting amount Q2 of the brush 92 with respect to the photoconductor 1 becomes a predetermined value, and the biasing force of the spring 95 is the biting amount Q of the brush 92 with respect to the lubricant supply body 91.
1 and the pressing force of the brush 92 against the lubricant supply body 91 are set to be a predetermined value.

The bite amount Q1 is expressed by the following equation (1). Q1 = L0-L1 (1) where L0 is the radius of the non-contact portion of the brush 92, and L1 is the brush 92, the shaft center BSX, and the lubricant supply body 91.
Is the distance between the closest points on the surface of.

The bite amount Q2 is expressed by the following equation (1). Q2 = L0-L2 (2) However, L2 is the distance between the closest points of contact between the brush 92, the shaft center BSX, and the surface of the photoconductor 1.

The predetermined values of the biting amounts Q1 and Q2 and the pressing force are preferably variable. That is, it is preferable to perform control so that the predetermined value changes depending on factors such as the amount of toner formed on the photoconductor 1.

The amount of lubricant applied to the photoconductor 1 is controlled by displacing the support member 96 that supports the brush by the motor M2 and changing the biting amount Q2 of the brush 92 with respect to the photoconductor 1. Also, the coating amount is 95
The control is performed by displacing the support member 94 by the motor M2 and changing the pressing force of the spring 95 to change the biting amount Q1 of the brush 92 with respect to the lubricant supply body 91. That is, by changing the biting amount of the brush 92 with respect to the lubricant supplying body 91, the pressing force of the brush 92 with respect to the lubricant supplying body 91 changes substantially in proportion to the change of the biting amount, so that the lubrication stripped by the brush 92 is changed. The amount of agent changes.

By applying the lubricant to the photoconductor 1 using the lubricant applying means 9 described above, the lubricant is evenly applied over a long period of time, and in combination with the external additive, the transfer roller is formed. It is possible to effectively prevent hollow defects in the transfer using 51, and to effectively prevent image stains, fog, and density reduction due to toner filming. As a result, the replacement period of the image forming body and the cleaning unit is extended, and an image forming apparatus having a long maintenance cycle is realized. (2) The developing means 4 preferably uses a two-component developer containing a carrier and a toner as main components.

The toner has a number average particle diameter of 3 to 8 μm.
Those having m are preferred. To calculate the particle size distribution of the toner and measure the number average particle size, Coulter Counter TA-II,
It can be measured by using a Coulter Multisizer, SLAD1000 (laser diffraction particle size measuring device manufactured by Shimadzu Corporation), or the like.

In the present invention, a Coulter Multisizer was used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting the particle size distribution and a personal computer were connected and used.

By using a small particle size toner having a number average particle size of 3 to 8 μm, an image having high resolution and excellent sharpness is formed.

Fogging occurs with toner having a particle size smaller than 3 μm.
Toner scattering is likely to occur. If the toner exceeds 8 μm, the resolution and the sharpness are deteriorated. (3) A toner having a variation coefficient of the shape coefficient of 16% or less and a variation coefficient of the number distribution of 27% or less is preferable. Particularly, it is preferable to use a polymerized toner.

When the coefficient of variation of the shape factor of the toner exceeds 16%, the distribution of the charge amount of the toner becomes broad, and the surface of the photoreceptor is deteriorated due to abrasion, resulting in poor cleaning, and fogging and black spots are likely to occur during image formation. Become. Further, when the coefficient of variation of the number of toners exceeds 27%, the charge amount distribution of the toners is broadened, cleaning failure occurs, the image density is insufficient during image formation, and fogging and black spots are likely to occur.

The toner of the present invention preferably has a variation coefficient of toner shape coefficient of 14% to 2% and a variation coefficient of toner number of 25% to 5%. When the content is within the range, the deterioration of the photoreceptor surface due to abrasion is small, the cleaning property is excellent, the amount of film thickness loss is small, and fog and black spots are not generated during image formation, and a high density and clear image can be obtained. Particularly, there is little variation in performance between toners and photoconductors in a plurality of image forming units, which are peculiar to a tandem type color image forming apparatus, and a uniform color image without color misregistration can be obtained.

The toner shape coefficient, the variation coefficient of the toner shape coefficient, and the toner number variation coefficient will be described below.

(Shape Factor of Toner) The shape factor of the toner of the present invention is represented by the following calculation formula and represents the roundness of toner particles.

Toner shape factor = [(maximum diameter / 2) 2 ×
[pi]] / projected area Here, the maximum diameter refers to the width of the particle in which the distance between the parallel lines is maximum when the projected image of the toner particles on the plane is sandwiched by two parallel lines. The projected area means the area of the projected image of the toner particles on the plane.

For the shape factor of the toner of the present invention, the toner particles are photographed by magnifying the toner particles by a scanning electron microscope at a magnification of 2000, and the obtained photograph is "SCANNING IMA".
It is obtained by performing image analysis using "GEANALYZER" (manufactured by JEOL Ltd.). The present invention is
The shape factor of 00 toner particles is measured, and the average value thereof is used as the shape factor of the toner of the present invention.

(Variation Coefficient of Shape Factor of Toner) The variation coefficient of the shape coefficient of the toner of the present invention is calculated from the following formula.

Coefficient of variation of shape factor of toner = (S1 /
K) × 100 (%) In the formula, S1 represents the standard deviation of the shape factor of 100 toner particles, and K represents the average value of the shape factor.

The coefficient of variation of the shape factor of the toner is 16%.
In order to obtain a uniform toner by reducing the variation of the shape factor between the toner lots, preferably in the range of 14% to 2%, preferably, the resin particles constituting the toner are preferably produced by polymerization. In the step of fusing and molding (shape control) the resin particles thus formed, an appropriate process end time may be determined while monitoring the characteristics of the toner particles (colored particles) being formed. Here, to monitor means to incorporate a measuring device in-line and control process conditions based on the measurement result. That is, by incorporating the measurement of the shape and the like in-line, for example, in a polymerized toner formed by associating or fusing resin particles in an aqueous medium, the shape and particle size can be determined while performing sequential sampling in the steps such as fusing. It is measured, and the reaction is stopped when the desired shape is obtained. The monitoring method is not particularly limited,
A flow type particle image analyzer FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd.) can be used. This device is suitable because the shape can be monitored by performing image processing in real time while passing the sample liquid. That is, a pump or the like is used from the reaction field to constantly monitor and measure the shape and the like, and the reaction is stopped when the desired shape or the like is obtained.

(Toner Number Variation Coefficient) The number particle size distribution, number average particle diameter and number variation coefficient of the toner of the present invention are measured with a Coulter Counter TA or Coulter Multisizer (manufactured by Coulter Co.). In the present invention, a Coulter Multisizer was used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting the number particle size distribution and a personal computer were connected and used. The aperture used in the Coulter Multisizer was 100 μm, and the volume and number of toner particles of 2 μm or more were measured to calculate the number particle size distribution and number average particle size of the toner. The number average particle diameter represents the median diameter in the number particle size distribution. The number variation coefficient in the toner number particle size distribution (hereinafter referred to as the toner number variation coefficient) is calculated from the following formula.

Toner number variation coefficient = [S2 / Dn] ×
100 (%) In the formula, S2 represents the standard deviation in the number particle size distribution, and D2
n indicates a number average particle diameter (μm).

The method of controlling the number variation coefficient in the toner of the present invention is not particularly limited. For example, a method of classifying toner particles by wind force can be used, but classification in a liquid is effective for reducing the number variation coefficient. As a method of classifying in this liquid, there is a method of controlling the rotation speed and separately collecting and preparing toner particles according to the difference in sedimentation speed caused by the difference in toner particle diameter.

Particularly when the toner is produced by the suspension polymerization method, the classification operation is indispensable in order to keep the number variation coefficient of the toner to 27% or less. In the suspension polymerization method, it is necessary to disperse the polymerizable monomer into oil droplets having a desired size as a toner in an aqueous medium before the polymerization. That is, the large oil droplets of the polymerizable monomer are repeatedly mechanically sheared by a homomixer or a homogenizer to reduce the oil droplets to the size of toner particles. With such a method of shearing, the number particle size distribution of the obtained oil droplets becomes broad, and therefore the particle size distribution of the toner obtained by polymerizing the oil droplets also becomes broad. For this reason, classification operation is essential. (4) As the transfer means 5, it is preferable to use a transfer roller 51 having a metal shaft provided with a sponge-like rubber layer.

By using such transfer means,
Transfer is performed uniformly and with a high transfer rate, and further, voids and the like are effectively prevented.

<Embodiment 2 (Embodiment of the Second Invention)> The second invention is implemented in the image forming apparatus of FIG.

The second embodiment will be described below using the example of the image forming apparatus shown in FIG. 2, but the present invention is not limited to the example shown.

A second aspect of the present invention is a primary transfer means for transferring a toner image from the image forming body to the intermediate transfer body by an image forming body, a latent image forming means, a developing means, an intermediate transfer body, and a primary transfer roller. An image forming apparatus having a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material and a lubricant applying means for applying a lubricant to at least one of the image forming body and the intermediate transfer body, An image forming apparatus is characterized in that development is performed using a toner containing 0.01 to 2% by mass of an external additive.

In the transfer process using the transfer roller,
There is a case where a toner image is pressed by the transfer roller into a lump and is not transferred, and a phenomenon referred to as transfer omission occurs.
In particular, in a solid image having a large amount of toner, a transfer omission may occur, and a phenomenon referred to as a hollow image may occur in which a non-transferred portion occurs in the central portion of the solid image.

A lubricant such as a fatty acid metal salt is applied as a means for preventing hollowing. However, depending on the application of the lubricant, the hollow defect can be prevented to some extent, but there is a problem that toner filming occurs and the background stain and the density decrease easily occur. The second aspect of the present invention solves such a problem, and the second aspect of the present invention satisfactorily prevents hollow defects, and does not cause background stains or a decrease in concentration due to toner filming. An image is obtained.

The lubricant comprises a fatty acid metal salt, and specific examples of the lubricant include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, and other stearic acid metal salts, zinc oleate, manganese oleate, and the like. Metal oleate such as iron oleate, copper oleate, magnesium oleate, zinc palmitate,
Examples thereof include metal palmitate salts such as copper palmitate and magnesium palmitate, metal linoleate salts such as zinc linoleate and zinc linoleate, and metal ricinoleate salts such as zinc ricinoleate and lithium ricinoleate. Zinc stearate is particularly preferred.

The external additive is a property improving agent added to the toner after the toner particles are formed in the toner manufacturing process, and a lubricant is used in the present invention.

Lubricant was added to 0.0 based on the toner mass.
Addition of 1 to 2% by mass offsets voids and toner filming, but if less than 0.01% by mass of lubricant is added or no lubricant is added, toner filming is performed. Is likely to occur.

The preferred conditions in this embodiment are as follows. (1) The lubricant applying means preferably comprises a lubricant supplying body and a brush which is in contact with the lubricant supplying body and is in contact with at least one of the image forming body and the intermediate transfer body to apply the lubricant. .

The structures and functions of the lubricant supply body and the brush are the lubricant supply body 91 and the brush 92 shown in FIG. 3, and are as described above. FIG. 3B shows a lubricant applying means for applying a lubricant to the intermediate transfer body 20.

The biting amount Q1 of the brush 92 into the lubricant supply body 91, the pressing force of the brush 92 against the lubricant supply body 91 or the photoconductor 1 or the intermediate transfer body 2 of the brush 92.
As described above, the biting amount Q1 with respect to 0 can be made variable, but the biting amount Q2 of the brush 92 with respect to the intermediate transfer member 20 is intermediate with the rotation center BSX of the brush as shown in FIG. 3B. It is defined by the distance L2 between the closest points to the surface of the transfer body 20.

As shown in FIG. 4, the lubricant applying means 9 is
A lubricant is applied to the photoconductor 1 between the next transfer unit 5 and the cleaning unit 6. The lubricant applying means 9 shown in FIG.
Is provided in each of the image forming units 10Y, 10M, 10C and 10K.

FIG. 5 shows an example in which a lubricant applying means 9 for applying a lubricant is provided on the intermediate transfer member 20, and the lubricant applying means 9 is provided upstream of the cleaning means 6A.

As shown in FIG. 4, the lubricant applying means 9 is provided in the image forming portions 10Y, 10M, 10C and 10K to apply the lubricant to the photoconductors 1Y, 1M, 1C and 1K, and as shown in FIG. Alternatively, the lubricant may be applied to the intermediate transfer body 20 by providing it upstream of the cleaning means 6A. (2) The developing means 4 preferably uses a two-component developer containing a carrier and a toner as main components.

The toner has a number average particle size of 3 to 8 μm.
Those having m are preferred. The preferable conditions regarding the number average particle diameter of the toner are as described above. (3) A toner having a variation coefficient of the shape coefficient of 16% or less and a variation coefficient of the number distribution of 27% or less is preferable. Particularly, it is preferable to use a polymerized toner.

The preferable conditions regarding the variation coefficient of the shape factor and the number variation coefficient of the number distribution of the toner are as described above. (4) For the primary transfer means 5Y, 5M, 5C and 5K, it is preferable to use a transfer roller 51 having a metal shaft provided with a sponge-like rubber layer.

By using such transfer means,
Transfer is performed uniformly and with a high transfer rate, and further, voids and the like are effectively prevented. (5) The intermediate transfer member 20 has a volume resistivity of 1 × 10 ⁴
A belt-shaped intermediate transfer member having a density of 1 × 10 ¹³ Ωcm is preferable.

When the volume resistivity is lower than 1 × ⁴ Ωcm, the charge holding power of the intermediate transfer member is lowered, the toner holding power is lowered, toner scattering easily occurs, and the current in the transfer portion flows to the surroundings. Transfer failure may occur.
If the volume resistivity exceeds 1 × 10 ¹³ Ωcm, charges may remain on the intermediate transfer body 20 even after the transfer, which may affect the next transfer or cause a lightning strike.

The intermediate transfer member 20 contains carbon black,
A polyimide resin, a PET resin, or the like to which the above-described conductivity is imparted by dispersing a conductive powder such as a metal or a metal participant is preferably used. (6) With the intermediate transfer member 20 described in (5) above,
It is preferable to use a semiconductive roller having a resistance value of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω as the backup roller 7A as a backup member and the secondary transfer roller 51A constituting the secondary transfer means 5A.

For such a semi-conductive roller, the rubber or sponge rubber to which the above-mentioned conductivity is imparted by dispersing powder of carbon black, metal or metal oxide is preferably used.

If the resistance values of the backup roller 7A and the secondary transfer roller 51A are lower than 1 × 10 ⁵ Ω, a current may flow to a portion other than the transfer material, resulting in defective transfer. Further, if the resistance value exceeds 1 × 10 ¹⁰ Ω, the transfer current may be insufficient to cause transfer failure, and the voltage may increase to cause leakage. (7) FIG. 6 shows a preferred example of the primary transfer means 5X. The primary transfer means 5X in FIG. 6 is a general term for the primary transfer means 5Y, 5M, 5C and 5K in FIG.

The primary transfer roller 51X, which constitutes the primary transfer means 5X, comes into pressure contact with the photoconductor 1 (collectively the photoconductors 1Y, 1M, 1C and 1K) urged by the spring 53. Figure 6
In the example of (a), the nip roller 5 as a nip forming member is provided upstream of the primary transfer roller 51X in the moving direction of the intermediate transfer member.
4 are provided. The intersection P1 of the intermediate transfer body 20 and the straight line connecting the rotation center PCX of the photoconductor 1 and the rotation center TRX of the primary transfer roller 51X is located at the position P1 of the primary transfer roller 51X.
Then, the intermediate transfer body 20 starts contacting the photosensitive body 1 from the intersection of the intermediate transfer body 20 and the straight line connecting the rotation center of the nip roller 54 and the rotation center PCX of the photosensitive body 1.
The contact area of the intermediate transfer body 20 with respect to the photoconductor 1 is a distance PI-P2 from the contact start position P2 to the position P1 of the primary transfer roller 51X.

As a result of the experiment, it is desirable that the position P1 of the primary transfer roller 51X is not on the contact start position P2 but on the downstream side. Furthermore, the position P1 of the primary transfer roller is the contact area P1. -Intermediate transfer member 2 from the center point of P2
It is preferable that the positions are set within the range of 10 mm on the upstream side and the downstream side in the moving direction. When it exceeds 10 mm, the position where the transfer electric field is formed and the contact position of the transfer material are separated from each other, and the transfer may not be sufficiently performed.

FIG. 6B shows another example. FIG. 6B shows an example in which nip rollers 54 and 55 as nip forming members are provided on the upstream side and the downstream side of the position P1 of the primary transfer roller 51X in the moving direction of the intermediate transfer body. Figure 6 (b)
In the configuration, the intermediate transfer member 20 contacts the photoconductor 1 between the contact start position P2 formed by the nip roller 54 and the separation position P3 formed by the nip roller 55. Even with such a configuration, the position P1 of the primary transfer roller 51X is within the range of 10 mm from the center point of the contact region P1-P3 from the contact start position P2 to the separation position P3 in the upstream and downstream sides of the moving direction of the intermediate transfer member. It is preferable to set to the position. (8) FIG. 7 is an enlarged view of the secondary transfer portion.

In the secondary transfer portion, as shown in FIG. 7, the transfer material P is a driving roller and passes between the intermediate transfer body 20 and the secondary transfer roller 51A backed up by a backup roller 7A as a backup member. At the transfer position, the full-color toner image is transferred onto the transfer material P all at once.

At the transfer position, the transfer material P starts contact with the intermediate transfer member 20 at the contact start position P2. The radius of the backup roller 7A is set so that the separating force due to the linearity of the transfer material P used is larger than the adhesive force of the transfer material P to the intermediate transfer body 20. Therefore, the transfer material P after the transfer is subjected to the contact force of the toner or the like, and the intermediate transfer member 20.
However, the intermediate transfer body 20 bends and moves along the circumferential surface of the backup roller 7A while the transfer material P is in contact with the transfer material P.
Is separated from the intermediate transfer member 20. That is, the transfer material P is separated from the intermediate transfer body 20 at the separation position P3.

The position of the secondary transfer roller 51A, that is, the straight line connecting the rotation center 7AX of the backup roller 7A and the rotation center 7AX of the secondary transfer roller 51A is the intermediate transfer member 20.
The point P1 that intersects with the contact point P2-P3 is located at the upstream side and the downstream side 20 respectively in the moving direction of the intermediate transfer member 20.
It is preferable to set it within the range of mm. (9) The nip rollers 54 and 55 shown in FIG. 6 are displaceable, and the intermediate transfer member 20 is moved to the photosensitive member 1 during the transfer process.
It is preferable to displace the intermediate transfer body 20 away from the photoconductor 1 or reduce the contact pressure of the intermediate transfer body 20 by displacing the intermediate transfer body 20 to the retracted position shown by the dotted line when not in operation.

If the nip rollers 54 and 55 are held in the operating position even when the nip rollers 54 and 55 are at rest and are brought into contact with the photoconductor 1 by the strong pressure of the intermediate transfer body 20, the characteristics of the photoconductor 1 may be affected. (10) Secondary transfer roller 5 constituting secondary transfer means 5A
It is preferable to separate 1A from the intermediate transfer member 20 except during operation.

FIG. 8 shows the operation of the secondary transfer roller 51A for the transfer material P in the present embodiment.

As shown in the figure, the secondary transfer roller 51A has a predetermined length V3 at the leading and trailing ends of the length of the transfer material P.
The intermediate transfer body 20 is contacted in the range V1 (the range indicated by diagonal lines) to which is added, and it is separated from the intermediate transfer body 20 in the other range W2.

With such a structure, fatigue and dirt of the intermediate transfer member can be prevented. The predetermined length V3 is 100
About mm is preferable.

<Third Embodiment (Embodiment of the Third Present Invention)> The third present invention is implemented in the image forming apparatus of FIG.

The third embodiment will be described below using the example of the image forming apparatus shown in FIG. 1, but the present invention is not limited to the example shown.

In a third aspect of the present invention, a lubricant is applied to the image forming body, the latent image forming means, the developing means, the transfer means for transferring the toner image from the image forming body to the transfer material by the transfer roller, and the image forming body. In the image forming apparatus having the lubricant applying means, the detecting means for detecting the toner adhesion amount on the image forming body and the control means for controlling the lubricant applying means based on the output of the detecting means are provided. The gist is a characteristic image forming apparatus.

There is a means of applying a lubricant as a means for preventing the hollow portion. Although the application of the lubricant is effective in preventing the hollow portion, there is a problem that the uneven coating of the lubricant occurs to cause the hollow portion. The third aspect of the present invention corrects the uneven application of the lubricant by controlling the amount of application of the lubricant to prevent hollow defects. According to the third aspect of the present invention, a clear and high-density image can be obtained.

FIG. 9 shows the main part of this embodiment. Figure 9
9A shows a main part of the present embodiment, FIG. 9B shows a patch PT formed on the image carrier PC, and FIG.
9C and 9D show a control system. In this embodiment, the image carrier PC is the photoconductor 1 in FIG. 1, and the transfer means 5W is the transfer means 5 in FIG.
Therefore, in the following description, the image carrier PC will be described as the photoconductor 1 and the transfer unit 5W will be described as the transfer unit 5.

In the present embodiment, in the image forming apparatus of FIG. 1, based on the output of the sensor PS as the detection means for detecting the toner adhesion amount on the patch PT as the reference toner image formed on the photoconductor 1. Controlled. That is, the control means CR is the brush 9 of the lubricant applying means 9.
The motor M1 for rotating the motor 2 or the motor M2 for changing the position of the brush 92 or the pressing force of the spring 95 is controlled.

In the present embodiment, when the May switch of the image forming apparatus is turned on to start the apparatus, when the image forming process is started, when a predetermined number of images are formed, etc.
The image characteristics of the apparatus are monitored by exposing and developing the toner image on the photoconductor 1 based on the density data of the reference value to form a toner image, and detecting the toner adhesion amount in the formed toner image by the sensor PS. Control is performed.

In controlling the lubricant application amount, the photoconductor 1
A reference toner image is formed on the surface by latent image formation and development,
The image is transferred to the transfer material by the transfer means 5. Then, the toner adhesion amount of the patch PT on the photoconductor 1 after the transfer is detected by the sensor PS. When the detected toner adhesion amount is large, non-transfer such as void is occurring. Therefore, the control means CR controls to increase the amount of lubricant applied.

In the example shown in FIG. 9C, the motor M
1 and the rotation speed of the brush 92 is controlled to control the amount of lubricant applied.

Further, in the example shown in FIG. 9D, the supporting member 94 or 96 in FIG. 3 is controlled by controlling the motor M2.
Is applied to control the application amount by controlling the amount of bite Q1 of the brush 92 with respect to the lubricant supplier 91, the pressing force of the brush 92 with respect to the lubricant supplier 91 or the amount of bite Q2 of the brush 92 with respect to the object PC to be coated. It is also possible.

The preferred conditions in this embodiment are as follows. (1) The developing means 4 preferably uses a two-component developer containing a carrier and a toner as main components.

The toner has a number average particle size of 3 to 8 μm.
Those having m are preferred. The preferable conditions regarding the number average particle diameter of the toner are as described above. (2) It is preferable that the variation coefficient of the shape coefficient is 16% or less and the variation coefficient of the number distribution is 27% or less. Particularly, it is preferable to use a polymerized toner.

The conditions concerning the variation coefficient of the shape coefficient and the number variation coefficient in the number distribution are as described above. (3) As the transfer means 5, it is preferable to use a transfer roller 51 in which a sponge-like rubber layer is provided on a metal shaft.

By using such transfer means,
Transfer is performed uniformly and with a high transfer rate, and further, voids and the like are effectively prevented.

<Fourth Embodiment (Embodiment of the Fourth Present Invention)> The fourth present invention is implemented in the image forming apparatus of FIG.

The fourth embodiment will be described below with reference to the example of the image forming apparatus shown in FIG. 2, but the present invention is not limited to the example shown.

In the fourth aspect of the present invention, an image forming body, a latent image forming means, a developing means, an intermediate transfer body, a primary transfer means for transferring a toner image from the image forming body to a transfer material by a primary transfer roller, and 2 An image forming apparatus having a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material by a secondary transfer roller and a lubricant applying means for applying a lubricant to at least one of the image forming body and the intermediate transfer body. In the image described above, the image forming apparatus further comprises: first detecting means for detecting the toner adhesion amount on the image forming body, and first controlling means for controlling the lubricant applying means based on the output of the first detecting means. The forming device is a gist.

There is a means for applying a lubricant as a means for preventing the hollow portion. Although the application of the lubricant is effective in preventing the hollow portion, there is a problem that the uneven coating of the lubricant occurs to cause the hollow portion. The fourth aspect of the present invention corrects the uneven application of the lubricant by controlling the amount of application of the lubricant to prevent hollow spots. The fourth aspect of the present invention provides a clear and high-density image.

FIG. 9 shows the main part of this embodiment. Figure 9
9A shows a main part of the present embodiment, FIG. 9B shows a patch formed on the image carrier PC, and FIGS. 9C and 9D show a control system. In this embodiment, the image carrier PC is the photoconductors 1Y, 1M, 1 in FIG.
C and 1K, and the transfer means 5W is the primary transfer means 5Y, 5M, 5C and 5K in FIG. Therefore, in the following description, the image carrier PC and the photoconductors 1Y, 1M, 1C,
1K is a photoreceptor 1 generically, transfer means 5W is a transfer means 5Y, 5M, 5C and 5K.
This will be described as W. Further, in the present embodiment, the sensor PS is the first detection unit that detects the toner adhesion amount on the patch PT on the photoconductor PC, and the control unit CR is the first detection unit.
It is a first control means for performing control based on the output of the detection means.

The control of the toner adhesion amount by the first control means is the same as the control in the third embodiment. That is, when the untransferred portion such as a void occurs in the transfer by the primary transfer means 5X, the sensor PS detects the increase in the toner adhesion amount.

When the sensor PS detects an increase in the toner adhesion amount, the control means CR controls the motor M1 or M2 to increase the amount of lubricant applied to the photosensitive member 1.

<Fifth Embodiment (Embodiment of the Fifth Present Invention)> The fifth present invention is implemented in the image forming apparatus of FIG.

The fifth embodiment will be described below using the example of the image forming apparatus shown in FIG. 2, but the present invention is not limited to the example shown.

The fifth aspect of the present invention comprises an image forming body, a latent image forming means, a developing means, an intermediate transfer body, and a primary transfer means for transferring a toner image from the image forming body to a transfer material by means of a primary transfer roller. An image forming apparatus having a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material by a secondary transfer roller and a lubricant applying means for applying a lubricant to at least one of the image forming body and the intermediate transfer body. In the above image, an image having a second detection means for detecting the toner adhesion amount on the intermediate transfer member and a second control means for controlling the lubricant application means based on the output of the second detection means. The forming device is a gist.

There is a means for applying a lubricant as a means for preventing the hollow portion. Although the application of the lubricant is effective in preventing the hollow portion, there is a problem that the uneven coating of the lubricant occurs to cause the hollow portion. The fifth aspect of the present invention corrects the uneven application of the lubricant by controlling the application amount of the lubricant to prevent hollow defects. According to the fifth aspect of the present invention, a clear and high-density image can be obtained.

FIG. 9 shows a main part of this embodiment. Figure 9
9A shows a main part of the present embodiment, FIG. 9B shows a patch formed on the image carrier PC, and FIGS. 9C and 9D show a control system. In this embodiment, the image carrier PC is the intermediate transfer member 20 in FIG. 2, and the transfer means 5W is the secondary transfer means 5A in FIG. Therefore, in the following description, the image carrier PC and the intermediate transfer member 20 and the transfer unit 5W will be described as the secondary transfer unit 5A. Further, in the present embodiment, the sensor PS is the second detection unit that detects the toner adhesion amount on the patch PT on the photoconductor 1, and the control unit CR is the second detection unit.
It is the 2nd control means which controls based on the output of a detection means.

The control of the toner adhesion amount by the second control means is the same as the control in the third embodiment. That is, when the non-transferring such as the void occurs in the transfer by the secondary transfer unit 5W, the sensor PS detects the increase of the toner adhesion amount.

When the sensor PS detects an increase in the toner adhesion amount, the control means CR controls the motor M1 or M2 to increase the amount of lubricant applied to the intermediate transfer member 20.

In this embodiment, the control means CR uses the lubricant based on the output of the sensor PS as the detection means for detecting the toner adhesion amount on the patch PT as the reference toner image formed on the image carrier PC. The motor M1 or M2 of the coating means 9 is controlled.

In the fifth embodiment, the image carrier PC is the intermediate transfer body 20, the sensor PS is the second detection means for detecting the toner adhesion amount on the patch PT on the intermediate transfer body 20, and the control means CR. Is a second control means for controlling based on the output of the second detection means.

The control of the toner adhesion amount by the control means CR is the same as the control in the third embodiment. That is, when untransferred such as a void occurs in the transfer by the transfer unit 5 in FIG. 9 as the secondary transfer unit, the sensor PS detects the increase of the toner adhesion amount.

When the sensor PS detects an increase in the toner adhesion amount, the control means CR controls the motor M1 or M2 to increase the amount of lubricant applied to the intermediate transfer member 20.

The first detecting means is used to detect the toner adhesion amount on the patch PT on the photosensitive member 1, and the second detecting means is used to detect the toner adhesion amount on the patch PT on the intermediate transfer member 20, Photoconductor 1 and intermediate transfer body 20
An embodiment is also possible in which the amount of lubricant applied to the is controlled, and in such an embodiment, control according to the algorithm shown in Table 1 is performed.

[0134]

[Table 1]

Preferable conditions in the fourth and fifth embodiments are as follows. (1) The lubricant applying means preferably comprises a lubricant supplying body and a brush which is in contact with the lubricant supplying body and is in contact with at least one of the image forming body and the intermediate transfer body to apply the lubricant. .

The structures and functions of the lubricant supply body and the brush are the same as the lubricant supply body 91 and the brush 92 shown in FIG. 3, and are as described above.

The biting amount Q1 of the brush 92 with respect to the lubricant supply body 91, the pressing force of the brush 91 with respect to the lubricant supply body 91, or the photoconductor 1 or the intermediate transfer body 2 of the brush 91.
It is preferable to make the biting amount Q2 with respect to 0 variable, and the mechanism thereof is as shown in FIG. 3 and explained above.

As shown in FIG. 4, the lubricant applying means 9 is 1
A lubricant is applied to the photoconductor 1 between the next transfer unit 5 and the cleaning unit 6. The lubricant applying means 9 shown in FIG.
Is provided in each of the image forming units 10Y, 10M, 10C and 10K.

FIG. 5 shows an example in which a lubricant applying means 9 for applying a lubricant is provided on the intermediate transfer member 20, and the lubricant applying means 9 is provided upstream of the cleaning means 6A.

As shown in FIG. 4, the lubricant applying means 9 is provided in the image forming portions 10Y, 10M, 10C and 10K to apply the lubricant to the photoconductors 1Y, 1M, 1C and 1K, and as shown in FIG. Alternatively, the lubricant may be applied to the intermediate transfer body 20 by providing it upstream of the cleaning means 6A. (2) The developing means 4 preferably uses a two-component developer containing a carrier and a toner as main components.

The toner has a number average particle size of 3 to 8 μm.
Those having m are preferred. The preferable conditions regarding the number average particle diameter of the toner are as described above. (3) A toner having a variation coefficient of the shape coefficient of 16% or less and a variation coefficient of the number distribution of 27% or less is preferable. Particularly, it is preferable to use a polymerized toner.

The preferable conditions regarding the variation coefficient of the shape factor and the number variation coefficient of the number distribution of the toner are as described above. (4) For the primary transfer means 5Y, 5M, 5C and 5K, it is preferable to use a transfer roller 51 having a metal shaft provided with a sponge-like rubber layer.

By using such transfer means,
Transfer is performed uniformly and with a high transfer rate, and further, voids and the like are effectively prevented. (5) The intermediate transfer member 20 has a volume resistivity of 1 × 10 ⁴
A belt-shaped intermediate transfer member having a density of 1 × 10 ¹³ Ωcm is preferable.

The preferable conditions regarding the volume resistance of the intermediate transfer member are as described above. (6) With the intermediate transfer member 20 described in (5) above,
It is preferable to use a semiconductive roller having a resistance value of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω as the backup roller 7A as a backup member and the secondary transfer roller 51A constituting the secondary transfer means 5A.

The preferable conditions for the intermediate transfer member 20 and the backup member are as described above. (7) The primary transfer roller 51X is connected to the photosensitive member 1 and the intermediate transfer member 2.
It is preferable to provide it on the downstream side in the moving direction of the intermediate transfer member from the contact start point with 0, and the position of the primary transfer roller is upstream and downstream from the center point of the contact area of the intermediate transfer member 20 of the photosensitive member 1. It is as shown in FIG. 6 and explained above that it is preferable to set each within the range of 10 mm. (8) It is desirable to set the secondary transfer roller 51A within the range of 20 mm upstream and downstream of the center of the contact area between the intermediate transfer body 20 and the transfer material P in the moving direction of the intermediate transfer body. This is as shown in FIG. 7 and explained above. (9) The nip rollers 54 and 55 shown in FIG. 6 are displaceable, and the intermediate transfer member 20 is moved to the photosensitive member 1 during the transfer process.
The intermediate transfer member 20 is moved to the retracted position when it is not operated to separate the intermediate transfer member 20 from the photosensitive member 1 or the intermediate transfer member 20.
It is preferred to reduce the contact pressure of.

If the nip rollers 54 and 55 are held in the operating position even when the nip rollers 54 and 55 are at rest and are brought into contact with the photoconductor 1 by the strong pressure of the intermediate transfer body 20, the characteristics of the photoconductor 1 may be affected. (10) Secondary transfer roller 5 constituting secondary transfer means 5A
It is preferable to separate 1A from the intermediate transfer member 20 except when it is in operation, and to retract the secondary transfer roller to the non-operation position outside the range in which a predetermined distance, for example, 100 mm is added to the front end and the rear end of the transfer material P. Is preferable in FIG.
Is as described above.

<Sixth Embodiment (Embodiment of the Sixth Present Invention)> The sixth present invention is implemented in the image forming apparatus of FIG.

The sixth embodiment will be described below with reference to the example of the image forming apparatus shown in FIG. 2, but the present invention is not limited to the example shown.

A sixth aspect of the present invention relates to an image forming body, a latent image forming means, a developing means, an intermediate transfer body, and a primary transfer means for transferring a toner image from the image forming body to the intermediate transfer body by a primary transfer roller. In an image forming apparatus having a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material and a lubricant applying means for applying a lubricant to the image forming body, the intermediate transfer body has a thickness of 70 μm or less. The gist of the image forming apparatus is an endless belt.

The hollow defect can be prevented to some extent by appropriately selecting the resistance value of the intermediate transfer member. However, due to the thickness of the intermediate transfer member, an electric field in the thickness direction of the intermediate transfer member as well as a surface direction of the intermediate transfer member is generated. There is a problem that the electric field affects the transfer. It can be said that the voids are caused by the influence of the toner image on the transfer electric field, but the voids are more likely to occur due to the increase in the thickness of the intermediate transfer member. However, there is a transfer problem in the case of transferring the toner images of No. 2 and superimposing the toner images of the respective colors to form a full-color toner image.

That is, in the transfer step of transferring and superimposing the toner image of the second color on the intermediate transfer member on which the toner image of the first color is formed, the transfer rate and the first transfer rate at the portion where the toner image of the first color exists. The problem is that there is a difference in the transfer rate in the portion where the color toner image does not exist. In particular, when the toner image of the first color is a solid image, the transfer electric field is lowered and the hollow image is likely to occur.

According to the sixth aspect of the present invention, the hollow image phenomenon is satisfactorily prevented, and a clear and high-density image can be obtained.

The preferred conditions in this embodiment are as follows. (1) The lubricant applying means preferably comprises a lubricant supplying body and a brush which is in contact with the lubricant supplying body and is in contact with at least one of the image forming body and the intermediate transfer body to apply the lubricant. .

The structure and operation of the lubricant supply body and the brush are the same as the lubricant supply body 91 and the brush 92 shown in FIG. 3, and are as described above.

The biting amount Q1 of the brush 92 with respect to the lubricant supply body 91, the pressing force of the brush 91 with respect to the lubricant supply body 91, or the photoconductor 1 or the intermediate transfer body 2 of the brush 91.
It is preferable to make the biting amount Q2 with respect to 0 variable, and the mechanism thereof is as shown in FIG. 3 and explained above.

As shown in FIG. 4, the lubricant applying means 9 is 1
A lubricant is applied to the photoconductor 1 between the next transfer unit 5 and the cleaning unit 6. The lubricant applying means 9 shown in FIG.
Is provided in each of the image forming units 10Y, 10M, 10C and 10K.

FIG. 5 shows an example in which a lubricant applying means 9 for applying a lubricant is provided on the intermediate transfer member 20, and the lubricant applying means 9 is provided upstream of the cleaning means 6A.

As shown in FIG. 4, the lubricant applying means 9 is provided in the image forming sections 10Y, 10M, 10C and 10K to apply the lubricant to the photoconductors 1Y, 1M, 1C and 1K, and as shown in FIG. Alternatively, the lubricant may be applied to the intermediate transfer body 20 by providing it upstream of the cleaning means 6A. (2) The developing means 4 preferably uses a two-component developer containing a carrier and a toner as main components.

The toner has a number average particle diameter of 3 to 8 μm.
Those having m are preferred. The preferable conditions regarding the number average particle diameter of the toner are as described above. (3) A toner having a variation coefficient of the shape coefficient of 16% or less and a variation coefficient of the number distribution of 27% or less is preferable. Particularly, it is preferable to use a polymerized toner.

The preferable conditions regarding the variation coefficient of the shape coefficient and the number variation coefficient of the number distribution of the toner are as described above. (4) For the primary transfer means 5Y, 5M, 5C and 5K, it is preferable to use a transfer roller 51 having a metal shaft provided with a sponge-like rubber layer.

By using such transfer means,
Transfer is performed uniformly and with a high transfer rate, and further, voids and the like are effectively prevented. (5) The intermediate transfer member 20 has a volume resistivity of 1 × 10 ⁴
A belt-shaped intermediate transfer member having a density of 1 × 10 ¹³ Ωcm is preferable.

The intermediate transfer member 20 contains carbon black,
A polyimide resin, a PET resin or the like to which the above-mentioned conductivity is imparted by dispersing a conductive powder such as a metal or a metal oxide is preferably used. (6) With the intermediate transfer member 20 described in (5) above,
It is preferable to use a semiconductive roller having a resistance value of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω as the backup roller 7A as a backup member and the secondary transfer roller 51A constituting the secondary transfer means 5A.

The preferable conditions for the secondary transfer roller 51A and the backup member are as described above. (7) The primary transfer roller 51X is connected to the photosensitive member 1 and the intermediate transfer member 2.
It is preferable to provide it on the downstream side in the moving direction of the intermediate transfer body from the contact start point with 0, and the position of the primary transfer roller is upstream and downstream from the center point of the contact area between the photoconductor 1 and the intermediate transfer body 20. It is as shown in FIG. 6 and explained above that it is preferable to set each within the range of 10 mm. (8) It is desirable to set the secondary transfer roller 51A within the range of 20 mm upstream and downstream of the center of the contact area between the intermediate transfer body 20 and the transfer material P in the moving direction of the intermediate transfer body. This is as shown in FIG. 7 and explained above. (9) The nip rollers 54 and 55 shown in FIG. 6 are displaceable, and the intermediate transfer member 20 is moved to the photosensitive member 1 during the transfer process.
The intermediate transfer member 20 is moved to the retracted position when it is not operated to separate the intermediate transfer member 20 from the photosensitive member 1 or the intermediate transfer member 20.
It is preferred to reduce the contact pressure of.

If the nip rollers 54 and 55 are held in the operating position even when the nip rollers 54 and 55 are at rest and kept in contact with the photosensitive member 1 by the strong pressure of the intermediate transfer member 20, the characteristics of the photosensitive member 1 may be affected. (10) Secondary transfer roller 5 constituting secondary transfer means 5A
It is preferable to separate 1A from the intermediate transfer member 20 except when it is in operation, and to retract the secondary transfer roller to the non-operation position outside the range in which a predetermined distance, for example, 100 mm is added to the front end and the rear end of the transfer material P. Is preferable in FIG.
Is as described above.

[0165]

EXAMPLES Example 1 An image was formed using the image forming apparatus shown in FIG. 1 under the following conditions. Photoreceptor: A phthalocyanine pigment was used as a charge generating substance, and polycarbonate was used as a layer forming substance, and an organic photoreceptor layer having a charge generating layer and a charge transporting layer was formed on a drum-shaped aluminum substrate. The film thickness of the photosensitive layer was 25 μm, and the drum diameter was φ60 mm. -Linear velocity of movement of photoconductor: 180 mm / sec-Charging potential (charge potential of photoconductor in non-exposed portion): The surface potential of the photoconductor is detected by a potential sensor, and feedback control is performed based on the detection result. Controllable range: -50
0 to -900V, maximum exposure potential: 0 to -50V-Exposure: Scanning exposure using a semiconductor laser (LD) of 300 μW-Development: Reversal development using a two-component developer-Transfer: Transfer roller made of sponge rubber To use. Roller diameter: 20 mm, sponge rubber resistance: 1 x 1
0 ⁶ Ω, pressure on photoreceptor: 20 N, transfer voltage: 80 μA
Constant current control / Fixing: Heat roller fixing using a heating roller and pressure roller with a heater inside ・ Toner concentration of developer: 4 mass% ・ Lubricant: Solid block of 100% zinc stearate,
Block size: 8 x 10 x 335 mm-Brush: diameter φ18 mm, length 335 mm, 50 k / 2 of Toray acrylic fiber SA-7, 6.25 d
50 minutes per minute using a brush with a density of 5.4 mm ^2.
~ 600 times rotation speed range, initial rotation speed: 250 per minute
Rotate at one rotation speed. -Brush bite amount with respect to the lubricant supply body: 1 mm-Brush bite amount with respect to the photoconductor: 1 mm-Amount of lubricant agent in the toner supplied from the toner replenishing means:
An image was formed under the condition of 0.1% by mass or more to make 200,000 copies. As a result, all copies have high densities, fog,
The copy was a clear image with no background stains and no transfer omissions.

Incidentally, in the comparative example in which the image formation was carried out under the above-mentioned conditions in addition to the case where the lubricant was not applied and the case where the external additive was not added, the fog caused by the hollow image and the toner filming occurred. Furthermore, in the comparative example in which the lubricant was applied and the external additive (lubricant) was not added, no void was observed,
Fogging occurred due to toner filming.

Example 2 An image was formed under the following conditions using the image forming apparatus shown in FIG. Photoreceptor: A phthalocyanine pigment was used as a charge generating substance, and polycarbonate was used as a layer forming substance, and an organic photoreceptor layer having a charge generating layer and a charge transporting layer was formed on a drum-shaped aluminum substrate. The film thickness of the photosensitive layer was 25 μm, and the drum diameter was φ60 mm. -Linear velocity of movement of photoconductor: 180 mm / sec-Charging potential (charge potential of photoconductor in non-exposed portion): The surface potential of the photoconductor is detected by a potential sensor, and feedback control is performed based on the detection result. Controllable range: -50
0 to -900V, maximum exposure potential: 0 to -50V-Exposure: Scanning exposure using a semiconductor laser (LD) of 300 μW-Development: Reversal development using a two-component developer-Intermediate transfer member: From endless polyimide Belt, volume resistivity: 1 × 10 ⁸ Ωcm, tension of intermediate transfer member: 50
N. Primary transfer: A transfer roller made of sponge rubber is used. Roller diameter: 20 mm, sponge rubber resistance:
1 × 10 ⁶ Ω, pressure on photoconductor: 5N, transfer voltage: 20
Constant current control / secondary transfer for μA: A secondary transfer roller made of sponge rubber and a backup roller made of a rigid body were used, and those having a diameter of 31.6 mm were used. Resistance value of secondary transfer roller and backup roller: 1 × 10 ⁶ Ω ・ Fixing: Heating roller fixing using a heating roller and pressure roller with a heater inside ・ Toner concentration of developer: 4 mass% ・ Lubricant : Solid block of 100% zinc stearate,
Block size: 8 x 10 x 335 mm-Brush: diameter φ18 mm, length 335 mm, 50 k / 2 of Toray acrylic fiber SA-7, 6.25 d
50 minutes per minute using a brush with a density of 5.4 mm ^2.
~ 600 times rotation speed range, initial rotation speed: 250 per minute
Rotate at one rotation speed.・ Amount of brush digging into the lubricant supplier: 1 mm ・ Amount of brush digging into the photoreceptor: 1 mm ・ Amount of brush digging into the intermediate transfer member: 1 mm ・ Amount of lubricant in the toner supplied from the toner replenishing means:
An image was formed under the condition of 0.01% by mass or more to prepare 200,000 copies. As a result, all copies have high densities, fog,
The copy was a clear image with no background stains and no transfer omissions.

Incidentally, in the comparative example in which the image formation was performed under the above-mentioned conditions in addition to the case where the lubricant was not applied and the case where the external additive was not added, the fog caused by the hollow image and the toner filming occurred. Furthermore, in the comparative example in which the lubricant was applied and the external additive (lubricant) was not added, no void was observed,
Fogging occurred due to toner filming.

Example 3 An image was formed using the image forming apparatus shown in FIG. 1 under the following conditions. Photoreceptor: A phthalocyanine pigment was used as a charge generating substance, and polycarbonate was used as a layer forming substance, and an organic photoreceptor layer having a charge generating layer and a charge transporting layer was formed on a drum-shaped aluminum substrate. The film thickness of the photosensitive layer was 25 μm, and the drum diameter was φ60 mm. -Linear velocity of movement of photoconductor: 180 mm / sec-Charging potential (charge potential of photoconductor in non-exposed portion): The surface potential of the photoconductor is detected by a potential sensor, and feedback control is performed based on the detection result. Controllable range: -50
0 to -900V, maximum exposure potential: 0 to -50V-Exposure: Scanning exposure using a semiconductor laser (LD) of 300 μW-Development: Reversal development using a two-component developer-Transfer: Transfer roller made of sponge rubber To use. Roller diameter: 20 mm, sponge rubber resistance: 1 x 1
0 ⁶ Ω, pressure on photoreceptor: 20 N, transfer voltage: 80 μA
Constant current control / Fixing: Heat roller fixing using a heating roller and pressure roller with a heater inside ・ Toner concentration of developer: 4 mass% ・ Lubricant: Solid block of 100% zinc stearate,
Block size: 8 x 10 x 335 mm-Brush: diameter φ18 mm, length 335 mm, 50 k / 2 of Toray acrylic fiber SA-7, 6.25 d
50 minutes per minute using a brush with a density of 5.4 mm ^2.
~ 600 times rotation speed range, initial rotation speed: 250 per minute
Rotate at one rotation speed. -Brush biting into the lubricant supply body: 1 mm-Brush biting into the photoconductor: 1 mm-Reference patch, that is, a pattern of reference density, is formed on the photoconductor, and control is performed to maintain the density of the reference patch constant. The image is formed based on A 30 mm × 30 mm patch having dots of φ0.5 mm formed at 2 mm intervals was formed. -As a result of the experiment, it was confirmed that there is the following relationship between the toner adhesion amount in the reference patch, the void and the output of the sensor.

The sensor output in the non-image portion is 12 V, and the toner drop amount of 0.60 mg / cm ² or less does not cause the hollow phenomenon. The output of the sensor at this time is 6 ~
It was 8V. When the toner adhesion amount is 0.80 mg / cm ² or more, the hollow phenomenon occurs without fail. The output of the sensor at this time was 3 to 5V.

From the above experimental results, a patch is formed every 500 sheets of image formation, and a sensor is applied in the lubricant application control for controlling the rotation speed of the brush based on the output of the sensor which detects the toner amount of the patch. If the output is 6V or more, the control is terminated and the brush rotation speed set when the power is turned on is not changed. If the sensor output is less than 6V, the brush rotation speed is increased by 50 times per minute. Take control. The initial value of the brush rotation speed is returned to 250 times per minute 8 hours after the power is turned off.

By controlling the lubricant application under the above conditions,
A good image was obtained when the image formation of 0,000 sheets was performed. In the experiment in which an image was formed by rotating the brush at a constant rotation speed of 250 times per minute without performing the above control, a hollow defect occurred.

Example 4 An image was formed using the image forming apparatus shown in FIG. 2 under the following conditions. Photoreceptor: A phthalocyanine pigment was used as a charge generating substance, and polycarbonate was used as a layer forming substance, and an organic photoreceptor layer having a charge generating layer and a charge transporting layer was formed on a drum-shaped aluminum substrate. The film thickness of the photosensitive layer was 25 μm, and the drum diameter was φ60 mm. -Linear velocity of movement of photoconductor: 180 mm / sec-Charging potential (charge potential of photoconductor in non-exposed portion): The surface potential of the photoconductor is detected by a potential sensor, and feedback control is performed based on the detection result. Controllable range: -50
0 to -900V, maximum exposure potential: 0 to -50V-Exposure: Scanning exposure using a semiconductor laser (LD) of 300 μW-Development: Reversal development using a two-component developer-Intermediate transfer member: From endless polyimide Belt, volume resistivity: 1 × 10 ⁸ Ωcm ・ Primary transfer: A transfer roller made of sponge rubber is used. Roller diameter: 20 mm, sponge rubber resistance:
1 × 10 ⁶ Ω, pressure on photoconductor: 5N, transfer voltage: 20
Constant current control to μA, distance between primary transfer means for each color: 95
mm ・ Secondary transfer: Transfer using a semi-conductive transfer roller, transfer voltage is formed with a constant current of 80 μA ・ Fixing: Heating roller fixing with a heater inside and heating roller fixing using a pressure roller ・ Intermediate transfer Body tension: 50N-Brush: diameter φ18mm, length 335mm, 50k / 2 of Toray acrylic fiber SA-7, 6.25d
50 minutes per minute using a brush with a density of 5.4 mm ^2.
~ 600 times rotation speed range, initial rotation speed: 250 per minute
Rotate at one rotation speed.・ Amount of bite of brush into photoreceptor and intermediate transfer body: 1m
m. A reference patch, that is, a pattern of reference density is formed on the photoconductor, and image formation is performed under the control of maintaining the density of the reference patch constant. A 30 mm × 30 mm patch having dots of φ0.5 mm formed at 2 mm intervals was formed. As a result of the experiment, a patch was formed on the photoconductor and the toner adhesion amount on the patch on the photoconductor was detected by the sensor, and the relationship between the toner adhesion amount and the void was examined.

It was confirmed that the sensor output in the non-image area was 12 V, and the following relationship was found between the toner adhesion amount in the reference patch, the void and the sensor output.

The output of the sensor which does not cause a void is 8 to 10
V, and the sensor output was 3.5 to 7.9 V, in which a void was generated. Brush drive control: From the above experimental results, in the lubricant application control for controlling the rotation speed of the brush based on the output of the sensor that forms a patch for each image formation of 500 sheets and detects the toner amount of the patch, If the sensor output is 8V or higher, control is terminated and the brush rotation speed set at power-on is not changed. If the sensor output is less than 8V, the brush rotation speed is 50 times per minute. Control to raise. The initial value of the brush rotation speed is returned to 250 times per minute 8 hours after the power is turned off.

By controlling the lubricant application under the above conditions, 2
A good image was obtained when the image formation of 0,000 sheets was performed. In the experiment in which an image was formed by rotating the brush at a constant rotation speed of 250 times per minute without performing the above control, a hollow defect occurred.

Example 5 An image was formed using the image forming apparatus shown in FIG. 2 under the following conditions. Photoreceptor: A phthalocyanine pigment was used as a charge generating substance, and polycarbonate was used as a layer forming substance, and an organic photoreceptor layer having a charge generating layer and a charge transporting layer was formed on a drum-shaped aluminum substrate. The film thickness of the photosensitive layer was 25 μm, and the drum diameter was φ60 mm. -Linear velocity of movement of photoconductor: 180 mm / sec-Charging potential (charge potential of photoconductor in non-exposed portion): The surface potential of the photoconductor is detected by a potential sensor, and feedback control is performed based on the detection result. Controllable range: -50
0 to -900V, maximum exposure potential: 0 to -50V-Exposure: Scanning exposure using a semiconductor laser (LD) of 300 μW-Development: Reversal development using a two-component developer-Intermediate transfer member: From endless polyimide Belt, volume resistivity: 1 × 10 ⁸ Ωcm ・ Primary transfer: A transfer roller made of sponge rubber is used. Roller diameter: 20 mm, sponge rubber resistance:
1 × 10 ⁶ Ω, pressure on photoconductor: 5N, transfer voltage: 20
Constant current control to μA, distance between primary transfer means for each color: 95
mm ・ Secondary transfer: Transfer using a semi-conductive transfer roller, transfer voltage is formed with a constant current of 80 μA ・ Fixing: Heating roller fixing with a heater inside and heating roller fixing using a pressure roller ・ Intermediate transfer Body tension: 50N-Brush: diameter φ18mm, length 335mm, 50k / 2 of Toray acrylic fiber SA-7, 6.25d
50 minutes per minute using a brush with a density of 5.4 mm ^2.
~ 600 times rotation speed range, initial rotation speed: 250 per minute
Rotate at one rotation speed.・ Amount of bite of brush into photoreceptor and intermediate transfer body: 1m
m. A reference patch, that is, a pattern of reference density is formed on the photoconductor, and image formation is performed under the control of maintaining the density of the reference patch constant. A 30 mm × 30 mm patch having dots of φ0.5 mm formed at 2 mm intervals was formed. As a result of the experiment, a patch was formed on the intermediate transfer member, the toner adhesion amount on the patch on the intermediate transfer member was detected by a sensor, and the relationship between the toner adhesion amount and the void was examined.

It was confirmed that the sensor output in the non-image portion was 10 V, and the following relationship was found between the toner adhesion amount in the reference patch, the void and the sensor output.

The sensor output is 3 to 3 when no void occurs.
The sensor output was 5V, and the output of the sensor in which the hollow portion occurred was 4 to 9V. -Brush drive control: From the above experimental results, a rotation speed of a brush that forms a patch for each image formation of 500 sheets and applies a lubricant to the intermediate transfer member based on the output of the sensor that detects the toner amount of the patch. When the sensor output is 3.5V or less in the lubricant application control for controlling the control, the control is terminated and the brush rotation speed set when the brush is turned on is not changed, and the sensor output exceeds 3,5V. In addition, control is performed to increase the brush rotation speed by 50 times per minute.
The initial value of the brush rotation speed is returned to 250 times per minute 8 hours after the power is turned off.

By controlling the lubricant application under the above conditions,
A good image was obtained when the image formation of 0,000 sheets was performed. In the experiment in which an image was formed by rotating the brush at a constant rotation speed of 250 times per minute without performing the above control, a hollow defect occurred.

Example 6 An image was formed using the image forming apparatus shown in FIG. 2 under the following conditions. Photoreceptor: A phthalocyanine pigment was used as a charge generating substance, and polycarbonate was used as a layer forming substance, and an organic photoreceptor layer having a charge generating layer and a charge transporting layer was formed on a drum-shaped aluminum substrate. The film thickness of the photosensitive layer was 25 μm, and the drum diameter was φ60 mm. -Linear velocity of movement of photoconductor: 180 mm / sec-Charging potential (charge potential of photoconductor in non-exposed portion): The surface potential of the photoconductor is detected by a potential sensor, and feedback control is performed based on the detection result. Controllable range: -50
0 to -900V, maximum exposed area potential: 0 to -50V-Exposure: Scanning exposure using a semiconductor laser (LD) of 300 μW-Development: Reversal development using a two-component developer-Intermediate transfer member: Endless polyimide Belt, volume resistivity: 1 × 10 ⁸ Ωcm, tension of intermediate transfer member: 50
N. Primary transfer: A transfer roller made of sponge rubber is used. Roller diameter: 20 mm, sponge rubber resistance:
1 × 10 ⁶ Ω, pressure on photoconductor: 5N, transfer voltage: 20
Constant current control / secondary transfer to μA: A secondary transfer roller made of sponge rubber and a backup roller made of a rigid body were used, and those having a diameter of 31.6 mm were used. Resistance value of secondary transfer roller and backup roller: 1 × 10 ⁶ Ω ・ Fixing: Heating roller fixing using a heating roller and pressure roller with a heater inside ・ Toner concentration of developer: 4 mass% ・ Lubricant : Solid block of 100% zinc stearate,
Block size: 8 x 10 x 335 mm-Brush: diameter φ18 mm, length 335 mm, 50 k / 2 of Toray acrylic fiber SA-7, 6.25 d
50 minutes per minute using a brush with a density of 5.4 mm ^2.
~ 600 times rotation speed range, initial rotation speed: 250 per minute
Rotate at one rotation speed.・ Amount of brush digging into the lubricant supplier: 1 mm ・ Amount of brush digging into the photoreceptor: 1 mm ・ Amount of brush digging into the intermediate transfer member: 1 mm ・ Amount of lubricant in the toner supplied from the toner replenishing means:
An image forming step of forming an image in which 0.01% by mass hollow image easily occurs, that is, a solid image of high density was carried out by using an intermediate transfer member having various thicknesses.

The experimental results are shown in FIG. In the figure, C
V1 is the dropout occurrence rate when a lubricant is applied, CV2
Indicates the dropout occurrence rate when no lubricant is applied. As is clear from FIG. 10, the application rate of the lubricant reduces the incidence of voids, and the incidence of voids was 30% or less when the thickness of the intermediate transfer member was 70 μm or less. This occurrence rate indicates a level at which the hollow image does not occur in all images in the actual image formation, and shows that the hollow image is sufficiently prevented by using the intermediate transfer member having a thickness of 70 μm. .

[0183]

The effects of the present invention are set forth in claims 1-4, 7, 13-15, and 18,
According to the invention of 19 or 20, a hollow image phenomenon in which the central portion of a solid image is untransferred is favorably prevented, and background stains, fog, density reduction due to toner filming are favorably prevented, and a clear and high density is obtained. An image forming apparatus for forming the image of is realized.

According to the invention of claim 5, 16, 37, 51 or 78, an image forming apparatus for forming an image of high image quality having high resolution and excellent sharpness is realized.

According to the invention of claim 6, 17, 38, 52 or 79, an image forming apparatus is realized which prevents fog and black spots, prevents wear and deterioration of the photoconductor, and forms an image of high image density. .

Claims 8-10, 21-24, 81 or 8
According to the second aspect of the present invention, since the amount of lubricant applied can be adjusted, even when various image forming conditions such as environmental changes fluctuate, there is a problem such as occurrence of hollowing due to fluctuations. To be prevented.

According to the eleventh, thirty-seventh, seventy-seventh, sixty-fifth, or ninety-third aspect of the invention, since the secondary transfer for transferring the toner image from the intermediate transfer to the transfer material is stably carried out, a high quality image is stably formed. The image forming apparatus is realized.

According to the invention of claim 12, 35, 48, 74 or 93, an image forming apparatus for forming a clear and high-density color image is realized.

Claims 25, 26, 27, 69, 70, 7
According to the invention of 1, 84 or 85, an image forming apparatus is realized in which image scattering and the like during transfer are prevented, transfer is performed at a high transfer rate, and an image of high image quality is formed.

Claims 28, 29, 63, 64, 68, 8
According to the invention of 6 or 87, since the transfer for forming the toner image from the image forming body to the intermediate transfer body is stably carried out, an image forming apparatus for stably forming a high quality image is realized.

According to the thirty-third, thirty-one, sixty-sixth, sixty-seventh, eighty-eighth or eighty-ninth aspect of the invention, the intermediate transfer member is separated from the image forming body or comes into contact with the image forming body at a low pressure when it is not operated. The deterioration of the image forming body such as the body is prevented, and the life of the image forming body is extended.

According to the invention of claim 33, 34, 72, 73, 91 or 92, the contact between the intermediate transfer member and the secondary transfer roller is released when the intermediate transfer member is not in operation, so that the deterioration of the intermediate transfer member and the secondary transfer roller. Are prevented and their life is extended.

Claims 36, 39 to 46, 49, 50, 5
According to the inventions of 3 to 62, 75, 76, 77, 80 or 83, an image forming apparatus that stably prevents a hollow image and forms an image of high image quality is realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a monochrome image forming apparatus which is an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a color image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing details of a lubricant applying unit.

FIG. 4 is a diagram showing an example in which a lubricant applying unit for applying a lubricant is provided on a photoconductor.

FIG. 5 is a diagram showing an example in which a lubricant applying unit for applying a lubricant is provided on the intermediate transfer member.

FIG. 6 is a diagram showing an example of primary transfer means.

FIG. 7 is an enlarged view of a secondary transfer portion.

FIG. 8 is a diagram showing an operation of a secondary transfer roller.

FIG. 9 is a diagram showing a main part of a third embodiment of the present invention.

FIG. 10 is a graph showing experimental results in Example 6 of the present invention.

[Explanation of symbols]

1, 1Y, 1M, 1C, 1K photoconductor 2, 2Y, 2M, 2C, 2K charging means 3, 3Y, 3M, 3C, 3K exposure means 4, 4Y, 4M, 4C, 4K developing means 41 Development sleeve 42 Toner supply means 5,5W transfer means 5Y, 5M, 5C, 5K, 5X Primary transfer means 5A secondary transfer means 6A, 6Y, 6M, 6C, 6K, 8 cleaning means 9 Lubricant application means 51 transfer roller 51X primary transfer roller 51A secondary transfer roller 91 Lubricant supplier 92 brush

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 9/10 G03G 15/08 115 15/08 115 15/16 507 103 15/16 15/08 507L 103 9 / 08 361 (72) Inventor Hiroshi Morimoto 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Masashi Saito 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock F term (reference) 2H005 AA08 AA15 AA21 CA25 EA05 EA07 FA01 2H027 DA09 DA10 EA18 2H077 DA03 DA31 DA47 DA63 EA03 2H134 KG04 KG07 KH01 LA01 LA02 2H200 GA44 GA45 GB12 HB12 JA28 JC03 JC07 JC09 JC16 JC18 KA12 LA06 LA14 LA08 MA18 MA01 MA04 MA12 MA04 MA12 MA04 MA12 MA04 MA12 MA04 MA04 MA12 MA04 MA12 MA04 MA12 MA04 MA12 MA04 MA12 MA04 MA12 MA04 MA12

Claims (93)

[Claims] 1. An image forming body, a latent image forming means, a developing means, a transfer means for transferring a toner image from the image forming body to a transfer material by a transfer roller, and a lubricant applying means for applying a lubricant to the image forming body. In the image forming apparatus having the above, the developing unit may add an external additive made of a lubricant in an amount of 0.01 to 2
An image forming apparatus, characterized in that development is performed using a toner containing mass%. 2. The image forming apparatus according to claim 1, wherein the lubricant is a fatty acid metal salt. 3. The image forming apparatus according to claim 1, wherein the lubricant applied to the image forming body is made of zinc stearate or calcium stearate. 4. The image forming apparatus according to claim 1, wherein the developing unit develops using a two-component developer containing toner and carrier as main components. 5. The toner used in the developing means is 3 to.
The image forming apparatus according to claim 1, having a number average particle diameter of 8 μm. 6. The toner according to claim 1, wherein a variation coefficient of the shape factor of the toner used in the developing unit is 16% or less, and a number variation coefficient of the number distribution is 27% or less. The image forming apparatus according to any one of items. 7. The lubricant applying means is composed of a lubricant supplier and a brush in contact with the lubricant supplier, and the brush is in contact with the image forming body to perform the application. The image forming apparatus according to any one of 1 to 6. 8. The image forming apparatus according to claim 7, wherein the amount of bite of the brush into the lubricant supply body is variable. 9. The method according to claim 7, wherein the amount of bite of the brush into the image forming body is variable.
The image forming apparatus according to item 1. 10. The image forming apparatus according to claim 7, wherein the pressing force of the lubricant supply body against the brush is variable. 11. The transfer roller is arranged within a range of 20 mm in each of the upstream side and the downstream side in the moving direction of the image forming body with respect to the center point of the contact area between the image forming body and the transfer material. The image forming apparatus according to any one of claims 1 to 10. 12. A lubricant is applied to the image forming body, the latent image forming means, the developing means, the transfer means for transferring a toner image from the image forming body to a transfer material by the transfer roller, and the image forming body. The image forming apparatus according to any one of claims 1 to 11, wherein a plurality of image forming units having the lubricant applying unit are provided to form a color image. 13. An image forming body, a latent image forming means, a developing means,
Intermediate transfer body, primary transfer means for transferring a toner image from the image forming body to the intermediate transfer body by a primary transfer roller, secondary transfer means for transferring the toner image from the intermediate transfer body to a transfer material, and the image forming In an image forming apparatus having a lubricant applying means for applying a lubricant to at least one of a body and the intermediate transfer body, the developing means comprises 0.01 to 2 external additives made of a lubricant.
An image forming apparatus, characterized in that development is performed using a toner containing mass%. 14. The image forming apparatus according to claim 13, wherein the lubricant comprises a fatty acid metal salt. 15. The image forming apparatus according to claim 13, wherein the lubricant applied to the image forming body contains zinc stearate or calcium stearate. 16. The image forming apparatus according to claim 13, wherein the toner used in the developing unit has a number average particle diameter of 3 to 8 μm. 17. The variation coefficient of the shape factor of the toner used in the developing unit is 16% or less, and the number variation coefficient of the number distribution is 27% or less. The image forming apparatus according to any one of items. 18. The image forming apparatus according to claim 13, wherein the developing unit performs development using a two-component developer containing toner and carrier as main components. 19. The lubricant applying means comprises a lubricant supplying body and a brush that contacts the lubricant supplying body, and the brush contacts the image forming body to perform the coating. The image forming apparatus according to any one of 13 to 18. 20. The lubricant applying means comprises a lubricant supplier and a brush that contacts the lubricant supplier, and the brush contacts the intermediate transfer member to apply the lubricant. The image forming apparatus according to any one of 13 to 19. 21. The image forming apparatus according to claim 19, wherein the amount of bite of the brush into the lubricant supply body is variable. 22. The image forming apparatus according to claim 19, wherein the amount of bite of the brush into the image forming body is variable. 23. The image forming apparatus according to claim 20, wherein the amount of bite of the brush into the intermediate transfer member is variable. 24. The image forming apparatus according to claim 20, wherein the pressing force of the lubricant supply member against the brush is variable. 25. The intermediate transfer member has a volume resistivity of 1 ×.
The image forming apparatus according to any one of claims 13 to 24, comprising an endless belt of 10 ⁴ to 1 × 10 ¹³ Ωcm. 26. The secondary transfer means has a secondary transfer roller, and the intermediate transfer member has a volume resistivity of 1 × 10 ⁴ to 10.
It consists of an endless belt of 1 × 10 ¹³ Ωcm,
The image forming apparatus according to claim 13, wherein the secondary transfer roller has a resistance value of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω. 27. A backup member for pressing the intermediate transfer member against the secondary transfer roller is provided, and the secondary transfer roller and the backup member are each 1 × 10.
The image forming apparatus according to claim 13, having a resistance value of ⁵ to 1 × 10 ¹⁰ Ω. 28. The primary transfer roller is disposed downstream of a contact start position of the image forming body and the intermediate transfer body in a moving direction of the intermediate transfer body.
28. The image forming apparatus according to any one of items 27 to 27. 29. The primary transfer roller is arranged within a range of 10 mm upstream and downstream in the moving direction of the intermediate transfer member from the center point of the contact area between the image forming member and the intermediate transfer member. The image forming apparatus according to any one of claims 13 to 28, wherein: 30. A nip forming member arranged upstream of the primary transfer means in the moving direction of the intermediate transfer body to bring the intermediate transfer body into contact with the image forming body, the nip forming member comprising:
The image forming apparatus according to any one of claims 13 to 29, wherein the image forming apparatus is displaceable so as to be set at a position where it does not come into contact with the image forming body except at least during execution of the transfer step. 31. The image forming apparatus according to claim 30, wherein the nip forming member includes a driven roller made of metal. 32. The secondary transfer roller is arranged within a range of 20 mm each on the upstream side and the downstream side in the moving direction of the image forming body with respect to the center point of the contact area between the image forming body and the transfer material. The image forming apparatus according to any one of claims 13 to 31, characterized in that. 33. The secondary transfer means has a secondary transfer roller which can be brought into contact with and separated from the intermediate transfer member, and the secondary transfer roller is located at a position a predetermined distance forward from the leading edge of the transfer material and is transferred. 14. The apparatus is apart from the intermediate transfer body except for contacting the intermediate transfer body and pressing the transfer material against the intermediate transfer body between positions rearward of a rear edge of the material by a predetermined distance. The image forming apparatus according to any one of 32. 34. The image forming apparatus according to claim 33, wherein the predetermined distance from the leading edge and the predetermined distance from the trailing edge are each set to 100 mm. 35. A color image is formed by having a plurality of image forming portions each having the image forming body, the latent image forming means, the developing means and the primary transfer means. The image forming apparatus according to any one of items. 36. An image forming body, a latent image forming means, a developing means,
In an image forming apparatus having a transfer unit that transfers a toner image from the image forming body to a transfer material by a transfer roller and a lubricant applying unit that applies a lubricant to the image forming body, An image forming apparatus comprising: a detection unit for detecting and a control unit for controlling the lubricant application unit based on an output of the detection unit. 37. The image forming apparatus according to claim 36, wherein the developing unit develops using a toner having a number average particle diameter of 3 to 8 μm. 38. The variation coefficient of the shape factor of the toner used in the developing unit is 16% or less, and the number variation coefficient in the number distribution is 27% or less. Item 37. The image forming apparatus according to Item 37. 39. The image forming apparatus according to claim 36, wherein the developing means performs development using a two-component developer containing toner and carrier as main components. 40. The lubricant applying means comprises a lubricant supplier and a brush that contacts the lubricant supplier, and the brush contacts the image forming body. The image forming apparatus according to any one of items. 41. The latent image forming unit and the developing unit form a reference toner image on the image forming body, and the detection unit detects a toner adhesion amount in the reference toner image. The image forming apparatus according to claim 36. 42. The image forming apparatus according to claim 36, wherein the lubricant applying unit includes a lubricant supply body and a brush that is in contact with the lubricant supply body. 43. The image forming apparatus according to claim 42, wherein the control unit controls the lubricant applying unit by controlling a rotation speed of the brush. 44. The image forming apparatus according to claim 42, wherein the control unit controls the lubricant applying unit by controlling a pressing force of the brush with respect to the lubricant supply body. 45. The control means controls the lubricant applying means by controlling a biting amount of the brush with respect to the lubricant supplying body.
2. The image forming apparatus according to item 2. 46. The image forming apparatus according to claim 42, wherein the control unit controls the lubricant applying unit by controlling a biting amount of the brush into the image forming body. 47. The transfer roller is arranged within a range of 20 mm in each of an upstream side and a downstream side in a moving direction of the image forming body with respect to a center point of a contact area between the image forming body and the transfer material. The image forming apparatus according to any one of claims 36 to 46. 48. A color image having a plurality of image forming portions having the image forming body, the latent image forming means, the developing means, the transfer means and the lubricant applying means for applying a lubricant to the image forming body. 37 is formed.
48. The image forming apparatus according to any one of 47 to 47. 49. An image forming body, a latent image forming means, a developing means,
An intermediate transfer body, a primary transfer means for transferring a toner image from the image forming body to a transfer material by a primary transfer roller, a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material by a secondary transfer roller, and In an image forming apparatus having a lubricant applying means for applying a lubricant to at least one of the image forming body and the intermediate transfer body, a first detecting means and a first detecting means for detecting a toner adhesion amount on the image forming body. An image forming apparatus comprising: first control means for controlling the lubricant applying means based on the output of the detecting means. 50. An image forming body, a latent image forming means, a developing means,
An intermediate transfer body, a primary transfer means for transferring a toner image from the image forming body to a transfer material by a primary transfer roller, a secondary transfer means for transferring a toner image from the intermediate transfer body to a transfer material by a secondary transfer roller, and An image forming apparatus having a lubricant applying means for applying a lubricant to at least one of the image forming body and the intermediate transfer body, the second detecting means and the second detecting means for detecting a toner adhesion amount on the intermediate transfer body. An image forming apparatus comprising: a second control unit that controls the lubricant applying unit based on an output of the detecting unit. 51. The image forming apparatus according to claim 49 or 50, wherein the developing unit develops using a toner having a number average particle diameter of 3 to 8 μm. 52. The variation coefficient of the shape factor of the toner used in the developing unit is 16% or less, and the number variation coefficient of the number distribution is 27% or less. The image forming apparatus according to any one of items. 53. The lubricant applying means comprises a lubricant supplier and a brush that contacts the lubricant supplier, and the brush contacts the image forming body. The image forming apparatus according to any one of items. 54. The image forming apparatus according to claim 49, wherein the lubricant applying unit includes a lubricant supplier and a brush that is in contact with the lubricant supplier. 55. The image forming apparatus according to claim 54, wherein the first control unit controls the lubricant applying unit by controlling a rotation speed of the brush. 56. The first control means controls the lubricant application means by controlling the pressing force of the brush against the lubricant supply body.
The image forming apparatus according to item 4. 57. The image forming apparatus according to claim 54, wherein the first control unit controls the lubricant applying unit by controlling a biting amount of the brush with respect to the lubricant supply body. . 58. The image forming apparatus according to claim 54, wherein the first control unit controls the lubricant applying unit by controlling an amount of bite of the brush into the image forming body. . 59. The image forming apparatus according to claim 54, wherein the second control unit controls the lubricant applying unit by controlling a rotation speed of the brush. 60. The second control means controls the lubricant application means by controlling the pressing force of the brush against the lubricant supply body.
The image forming apparatus according to item 4. 61. The image forming apparatus according to claim 54, wherein the second control unit controls the lubricant applying unit by controlling a biting amount of the brush with respect to the lubricant supplying body. . 62. The image forming apparatus according to claim 54, wherein the second control unit controls the lubricant applying unit by controlling a biting amount of the brush into the image forming body. . 63. The primary transfer roller is arranged downstream of a contact start position between the image forming body and the intermediate transfer body in a moving direction of the intermediate transfer body.
The image forming apparatus according to any one of to 62. 64. The primary transfer roller is arranged within a range of 10 mm upstream from the center of the contact area between the image forming body and the transfer material, and 10 mm downstream from the center in the moving direction of the image forming body. The image forming apparatus according to any one of claims 49 to 63, wherein: 65. The secondary transfer roller is arranged within a range of 20 mm each on the upstream side in the moving direction of the image forming body and the downstream side in the moving direction with respect to the center point of the contact area between the image forming body and the transfer material. The image forming apparatus according to any one of claims 49 to 64, wherein: 66. A nip forming member arranged upstream of the primary transfer means in the moving direction of the intermediate transfer member to bring the intermediate transfer member into contact with the image forming member, the nip forming member comprising:
66. The image forming apparatus according to claim 49, wherein the image forming apparatus is displaceable so as to be set at a position where it does not come into contact with the image forming body except at least during execution of a transfer process. 67. The image forming apparatus according to claim 66, wherein the nip forming member is a driven roller made of metal. 68. The image forming apparatus according to claim 49, wherein the primary transfer roller is a roller having a sponge-like rubber layer formed on a shaft made of metal. 69. The intermediate transfer member has a volume resistivity of 1 ×.
69. The image forming apparatus according to claim 49, comprising an endless belt of 10 < ⁴ > to 1 * 10 < ¹³ > [Omega] cm. 70. The secondary transfer means has a secondary transfer roller, and the intermediate transfer member has a volume resistivity of 1 × 10 ⁴ to.
It consists of an endless belt of 1 × 10 ¹³ Ωcm,
70. The image forming apparatus according to claim 49, wherein the secondary transfer roller has a resistance value of 1 × 10 ⁵ to 1 × 10 ¹⁰ Ω. 71. A backup member for pressing the intermediate transfer member against the secondary transfer roller is provided, and each of the secondary transfer roller and the backup member is 1 × 10.
The image forming apparatus according to any one of claims 49 to 70, which has a resistance value of ⁵ to 1 × 10 ¹⁰ Ω. 72. The secondary transfer means has a secondary transfer roller which can be brought into contact with and separated from the intermediate transfer member, and the secondary transfer roller is located at a position a predetermined distance forward from the leading edge of the transfer material and is transferred. 50. Apart from the intermediate transfer body except for contacting the intermediate transfer body and pressing the transfer material against the intermediate transfer body between a position rearward of a rear end edge of the material by a predetermined distance. 72. The image forming apparatus according to any one of 71. 73. The image forming apparatus according to claim 72, wherein the predetermined distance from the leading edge and the predetermined distance from the trailing edge are each set to 100 mm. 74. A color image is formed by having a plurality of image forming portions each having the image forming body, the latent image forming means, the developing means and the primary transfer means. The image forming apparatus according to any one of items. 75. An image forming body, a latent image forming means, a developing means,
Intermediate transfer body, primary transfer means for transferring a toner image from the image forming body to the intermediate transfer body by a primary transfer roller, secondary transfer means for transferring the toner image from the intermediate transfer body to a transfer material, and the image forming body An image forming apparatus having a lubricant applying unit for applying a lubricant to the intermediate transfer member, which comprises an endless belt having a thickness of 70 μm or less. 76. The lubricant applying device applies the lubricant to the image forming body at a position downstream of a transfer position of the primary transfer device and upstream of a charging position of the charging device. Item 75. The image forming apparatus according to Item 75. 77. The lubricant applying means has a lubricant supply body and a brush that contacts the lubricant supply body and the image forming body, and the brush is provided on the conductive support member and the conductive support member. 8. A semi-conductive fiber having a resistance value of 1 × 10 ² to 1 × 10 ¹³ Ω, which is transplanted.
The image forming apparatus according to claim 5 or claim 76. 78. The toner used by the developing means is 3-8.
8. It has a number average particle diameter of μm.
The image forming apparatus according to any one of 5 to 77. 79. The variation coefficient of the shape factor of the toner used in the developing unit is 16% or less, and the number variation coefficient of the number distribution is 27% or less. The image forming apparatus according to any one of items. 80. The image forming apparatus according to claim 75, wherein the developing unit performs development using a two-component developer containing toner and carrier as main components. 81. The amount of bite of the brush into the lubricant supply member is variable.
The image forming apparatus according to any one of 0. 82. The image forming apparatus according to claim 75, wherein the amount of biting of the brush into the image forming body is variable. 83. A lubricant applying means for applying a lubricant to the intermediate transfer member is provided.
The image forming apparatus according to any one of 1 to 82. 84. The intermediate transfer member has a volume resistivity of 1 ×.
The image forming apparatus according to any one of claims 75 to 83, which comprises an endless belt of 10 ⁴ to 1 × 10 ¹³ Ωcm. 85. A backup member for pressing the intermediate transfer member against the secondary transfer roller is provided, and each of the secondary transfer roller and the backup member is 1 × 10.
⁵ to 1 × 10 image forming apparatus according to any one of claims 75 to 84, characterized in that it comprises a resistance of ¹⁰ Omega. 86. The primary transfer roller is arranged downstream of a contact start position of the image forming body and the intermediate transfer body in a moving direction of the intermediate transfer body.
The image forming apparatus according to any one of 85 to 85. 87. The primary transfer roller is arranged within a range of 10 mm upstream and downstream in a moving direction of the intermediate transfer member from a center point of a contact area between the image forming member and the intermediate transfer member. The image forming apparatus according to any one of claims 75 to 86, wherein: 88. A nip forming member is disposed upstream of the primary transfer means in the moving direction of the intermediate transfer member to bring the intermediate transfer member into contact with the image forming member, and the nip forming member comprises:
88. The image forming apparatus according to claim 75, wherein the image forming apparatus is displaceable so as to be set at a position where it does not come into contact with the image forming body except at least during execution of the transfer step. 89. The image forming apparatus according to claim 88, wherein the nip forming member is a driven roller made of metal. 90. The secondary transfer roller is arranged within a range of 20 mm each on the upstream side in the moving direction of the image forming body and the downstream side in the moving direction with respect to the center point of the contact area between the image forming body and the transfer material. 90. The image forming apparatus according to claim 75. 91. The secondary transfer means has a secondary transfer roller that can be brought into contact with and separated from the intermediate transfer member, and the secondary transfer roller is located at a position a predetermined distance forward from the leading edge of the transfer material and transferred. 76. Apart from the intermediate transfer body, except for contacting the intermediate transfer body and pressing the transfer material against the intermediate transfer body between a position rearward of a rear edge of the material by a predetermined distance, 75. 90. The image forming apparatus according to any one of 90. 92. The image forming apparatus according to claim 91, wherein the predetermined distance from the leading edge and the predetermined distance from the rear edge are each set to 100 mm. 93. A color image is formed according to claim 75, wherein a plurality of image forming portions having the image forming body, the latent image forming means, the developing means and the primary transfer means are provided to form a color image. The image forming apparatus according to any one of items.