JPH08220902A - Image forming device - Google Patents

Abstract

PURPOSE: To prevent the occurrence of irregularities in an image due to a change in a transfer current by performing a primary transfer under a prescribed constant current control, storing the voltage generated at this time and deciding a transfer voltage required at a secondary transfer time based on the generated voltage value. CONSTITUTION: The constant current control of a primary transfer bias to be impressed on a primary transfer roller 5 from a power source E1 is executed by a previously decided current value. The voltage generated at this time is detected by a voltage detecting part 31, then, the mean value of the voltage is stored by the memory of a control part (CPU) 32 provided with memory/calculation functions. And also, at the primary transfer time, a secondary transfer roller 6 is separated from the intermediate transfer drum 4 so as to be in contact with a conductive roller 9, at this time, the constant current control is executed by a power source E2 while rotating the secondary transfer roller 6, and the voltage obtained at this time is detected by the voltage detecting part 33, and the mean value is stored in the memory of the CPU 32. And the secondary transfer voltage is calculated and decided by the CPU 32, then, a variable power source 34 is controlled, then, the voltage is impressed on the secondary transfer roller 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses an intermediate transfer member,
The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member is an image formed product in which a plurality of color component images such as color image information and multicolor image information are sequentially layered and transferred to synthesize and reproduce a color image or a multicolor image. It is effective as a color image forming apparatus for outputting or an image forming apparatus provided with a color image forming function and a multicolor image forming function, and an image without misregistration (color misregistration) of each component color image can be obtained. .

Specifically, a transferable image (toner image) is formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric as the first image carrier, which is generally a rotary drum type. An image forming process means such as an electrophotographic process and an electrostatic recording process is formed, and the image formed on the image bearing member is transferred onto an intermediate transfer member, which is generally a rotary drum type, by the first transfer member. Primary transfer is performed.

In the case of color image formation or multicolor image formation,
For each color component image, the process of forming the color component image on the image carrier and the process of primary transfer to the intermediate transfer body are sequentially and repeatedly performed, thereby aligning and transferring the respective color component images on the intermediate transfer body. The target color image or multicolor image is synthesized and reproduced.

Then, the superposed transfer composite image on the intermediate transfer member is collectively printed on a transfer material such as paper as a second image carrier by using a second transfer means opposed to the intermediate transfer member.
Next transfer.

The transfer material is introduced into the fixing means to fix the transferred image on the transfer material and output as an image-formed product.

As the intermediate transfer member, a medium resistance elastic layer formed on the outer peripheral surface of a substrate is often used. The middle resistance layer is made of an elastic material such as rubber or a metal such as carbon or zinc oxide. Oxide is dispersed to have a volume resistivity of 10 ⁵ to
It is adjusted to 10 ¹¹ Ω · cm.

The second transfer means opposed to the intermediate transfer body is generally a contact type transfer means, more specifically, a transfer roller which comes into contact with the intermediate transfer body via a transfer material. This transfer roller also has a core bar on which an elastic layer having a medium resistance is formed similarly to the intermediate transfer member.

[0009]

Such a transfer member has a large resistance value variation due to the environment such as temperature and humidity. Therefore, when there is no transfer material at the transfer site, the transfer means is controlled by a constant current. It has been proposed and put into practical use that the generated potential difference is held or stored, and when the transfer material is present in the transfer portion, the voltage value is multiplied by a coefficient and the constant voltage is controlled by a voltage to which a constant is added. .

This method can be applied to a system using an intermediate transfer member. However, the elastic layer whose resistance value is adjusted has a partial uneven resistance value due to the state of dispersion or foaming in the manufacturing process. When the constant secondary transfer bias is applied, the transfer current may partially change and an image defect may occur if the resistance value is uneven in the circumferential direction.

Accordingly, the present invention is directed to an image forming apparatus using an intermediate transfer member, and it is an object of the present invention to prevent the image from being disturbed due to a change in the transfer current due to the circumferential resistance unevenness of the intermediate transfer member and the secondary transfer means. And

[0012]

The present invention is an image forming apparatus having the following configuration.

(1) A means for forming an image on the image carrier is provided, and after the image formed on the image carrier is primarily transferred onto the intermediate transfer member by the first transfer means, the intermediate In an image forming apparatus for secondarily transferring an image on a transfer member onto a transfer material by using a second transfer unit facing the intermediate transfer member,
An image forming apparatus comprising: a unit for performing the primary transfer under a predetermined constant current control, a unit for storing a voltage generated there, and a unit for determining a transfer voltage at the secondary transfer based on the voltage value. .

(2) The image forming apparatus according to (1), wherein the voltage stored during the primary transfer is an average value of the voltages detected during the constant current control.

(3) The voltage stored during the primary transfer corresponds to the detected voltage during the constant current control in the circumferential position of the intermediate transfer member. Image forming apparatus.

(4) Having means for forming an image on the image bearing member, the image formed on the image bearing member is primarily transferred onto the intermediate transfer member by the first transfer means, and then the intermediate In an image forming apparatus for secondarily transferring an image on a transfer member onto a transfer material by using a second transfer unit facing the intermediate transfer member,
The voltage value when the second transfer means is controlled to a constant current is
2. An image forming apparatus comprising: a means for storing the transfer means in correspondence with the circumferential position of the transfer means; and a means for determining the transfer voltage at the secondary transfer based on the voltage value.

(5) The image forming apparatus described in (4) is characterized in that a part of the intermediate transfer member is made conductive and the second transfer means is brought into contact with the part for constant current control.

(6) The image forming apparatus according to (4), wherein the second transfer means is capable of coming into contact with and separating from the intermediate transfer body, and comes into contact with the conductive member at the time of separation so as to perform constant current control. apparatus.

(7) The image forming apparatus according to any one of (1) to (6), wherein the second transfer means is a transfer roller.

[0020]

In other words, the present invention detects the circumferential resistance value unevenness of the intermediate transfer member or the second transfer means, and calibrates and applies the secondary transfer bias to the second transfer means in accordance with the unevenness. As a result, it was possible to form a good image on the transfer material regardless of the uneven resistance value in the circumferential direction of the intermediate transfer body or the second transfer means.

[0021]

【Example】

<Embodiment 1> (FIGS. 1 and 2) (1) Schematic configuration of an example of an image forming apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus of the present example.
The image forming apparatus of this example is a color printer or a color copying machine using an electrophotographic process and using an intermediate transfer member.

Reference numeral 1 is an electrophotographic photosensitive drum as a first image carrier. For example, an OPC photoconductor layer (organic photoconductor layer) 1a is formed on the outer peripheral surface of the conductive drum substrate 1b, and at a predetermined peripheral speed (in this example, a process speed of 60 mm / sec) in the clockwise direction of the arrow. It is driven to rotate.

The photosensitive drum 1 is rotated by the primary charger 2 during rotation.
Are uniformly charged to a predetermined polarity and potential (charging step).

Then, on the charged surface, a first color component image of a target color image, for example, a first color component image of a target color image is formed by an image information exposure means (not shown) (modulated laser scanning exposure means, original image color separation projection exposure means, etc.). By receiving the exposure 3 of the magenta component image, an electrostatic latent image corresponding to the exposed image is formed on the surface of the rotating photoconductor drum (exposure step).

The latent image is developed with magenta toner by the magenta toner developing device 11M corresponding to the first color component image (developing step). At this time, the other cyan toner developing device 11C, yellow toner developing device 11Y, and black toner developing device 11BK are held at positions where they do not act on the photosensitive drum 1.

Reference numeral 4 denotes an intermediate transfer drum as an intermediate transfer member, which is disposed in contact with or in close proximity to the photoconductor drum 1 and has a counterclockwise direction indicated by an arrow forward in the rotational direction of the photoconductor drum 1. And is driven to rotate at substantially the same circumferential speed as the photosensitive drum 1.

The intermediate transfer drum 4 has a volume resistivity of 10 ⁵ to 1 by dispersing zinc oxide on the peripheral surface of the hollow substrate 4 b.
The medium resistance elastic body layer 4a having a thickness of 5 mm and adjusted to 0 ¹¹ Ω · cm is formed, and the hardness is 20 ° to 40 ° by an Asker C hardness meter. The perimeter is 450 mm, which is slightly longer than the length of the A3 size, and the width is 310 mm. Then, at the position of the first transfer portion T1 which is the contact nip portion (or the proximity portion) with the photosensitive drum 1, the first transfer means is provided on the inner surface side of the intermediate transfer drum opposite to the photosensitive drum 1 side. Is arranged in contact with a metal primary transfer roller 5 having an outer diameter of 10 mm, and the toner image on the photosensitive drum 1 side is intermediately transferred to the primary transfer roller 5 from a power source E1. A bias for transferring to the drum 4 side is applied.

A reference point 7 is provided on the intermediate transfer drum 4 to prevent the toner images of the respective colors from being displaced and to align the transfer material. As the reference point 7, a seam in which the rubber of the surface layer 4a is attached can be used.

Thus, the magenta toner image, which is the first color image formed on the photosensitive drum 1 as described above, is primarily transferred onto the peripheral surface of the intermediate transfer drum 4 at the first transfer portion T1. (Primary transfer process).

After the primary transfer, the surface of the rotating photosensitive drum 1 is cleaned by the cleaning device 8 which removes the transfer residual toner (cleaning step).

Reference numeral 6 denotes a secondary transfer roller as a second transfer means, which is a urethane rubber layer having a volume resistivity of 10 ⁶ to 10 ¹¹ Ω · cm as a medium resistance elastic layer on a core metal 6 b having an outer diameter of 10 mm. 6a is formed, the overall outer diameter is 20 mm, and the intermediate transfer drum 4 is rotationally driven in the clockwise direction of the forward arrow at a substantially constant circumferential speed with the intermediate transfer drum 4. Then, by a swinging means (not shown), a state where the intermediate transfer drum 4 is in contact with the intermediate transfer drum 4 as shown by a solid line and a state where the intermediate transfer drum 4 is separated as shown by a two-dot chain line.

Reference numeral 10 denotes a cleaning device for cleaning the surface of the intermediate transfer drum 4, which is controlled by swinging means (not shown) to switch between a state in which the intermediate transfer drum 4 is actuated and a state in which it is separated.

The primary transfer of the toner image from the photosensitive drum 1 side to the intermediate transfer drum 4 is performed in a state where the secondary transfer roller 6 and the cleaning device 10 are separated from the intermediate transfer drum 4 and the toner image is primary. 1 in the process of passing through the transfer section T1
An electric field formed by the primary transfer bias applied to the secondary transfer roller 5 causes the reference point 7 of the intermediate transfer drum 4 to pass through the primary transfer portion T1 by a predetermined distance with respect to the outer peripheral surface of the intermediate transfer drum 4. It is carried out from the position where it was made.

In the same manner as described above, the steps of charging the photosensitive drum 1, exposing, developing, primary transferring the intermediate transfer drum 4, and cleaning the photosensitive drum 1 are performed in the second color. The outer peripheral surface of the intermediate transfer drum 4 is sequentially executed for the component image (for example, cyan component image), the third color component image (for example, yellow component image), and the fourth color component image (for example, black component image). , The four toner images of a magenta toner image, a cyan toner image, a yellow toner image, and a black toner image are aligned with each other and superposed and transferred, whereby a target color image is synthesized and reproduced. Developing devices 11M, 11C, 11 for the photosensitive drum 1
Y · 11BK is switched to a corresponding one for each formation cycle of each color component image.

At a predetermined timing after the primary transfer of the final toner image of the fourth color component to the intermediate transfer drum 4 is started, a secondary transfer roller 6 as a second transfer means is formed.
Are contacted with the intermediate transfer drum 4 to form the secondary transfer portion T2, and the transfer material P as the second image carrier is supplied from the inside of the paper feed cassette 20 by the paper feed roller 21.
Are fed, and the transfer material P is introduced into the secondary transfer portion T2 at a predetermined timing by a transfer system including the transfer roller 22.
The transfer material P is timing conveyed with its front end aligned with the reference point 7 of the intermediate transfer drum 4, and in the process of passing through the secondary transfer portion T2, the power source E2 is supplied to the secondary transfer roller 6.
A secondary transfer bias applied from the intermediate transfer drum 4 causes the combined color toner images to be collectively transferred (secondary transfer step).

The transfer material P, which has undergone the secondary transfer of the toner image from the side of the intermediate transfer drum 4, is conveyed to the fixing device 12 and is subjected to heat and pressure fixing of the toner image (fixing step) to form a color image formed product. Is output as.

Further, the surface of the intermediate transfer drum 4 after the secondary transfer of the toner image onto the transfer material P is cleaned by receiving the residual toner after transfer removed by the cleaning device 10 which is switched to the position for acting on the drum 4. .

In FIG. 1, the photosensitive drum 1, the intermediate transfer drum 4, the primary transfer roller 5, and the secondary transfer roller 6 are shown.
The relationship of the diameter ratio or the perimeter ratio, etc., is not expressed accurately. The same applies to FIGS. 4 and 5 of Example 3 and Example 4 described later.

The first transfer means 5 need not be a metal roller, but may be a metal blade that contacts the inner surface of the intermediate transfer drum 4. Further, the intermediate transfer body 4 may be formed in a belt shape by using a soft material for the base, instead of the drum shape.

(2) Transfer Bias Control In this embodiment, image defects caused by uneven resistance values in the circumferential direction of the intermediate transfer drum 4 as an intermediate transfer member are prevented.

The primary transfer bias applied from the power source E1 to the primary transfer roller 5 as the first transfer means is constant-current controlled at a predetermined current value of 3 μA. The voltage generated at that time is detected by the voltage detection unit 31, and the average value V _1Ave (kV) of the voltage is stored in the memory of the control unit (CPU) 32 having a memory / arithmetic function.

At the time of primary transfer, the second transfer means 2
The secondary transfer roller 6 is separated from the intermediate transfer drum 4 and is in contact with the conductive roller 9. At this time, while the secondary transfer roller 6 is rotating, a constant current is controlled at 3 μA by the power source E2. The voltage is detected by the voltage detector 33, and the average value V _LoAve (kV) is stored in the memory of the controller 32.

Regarding the secondary transfer bias applied to the secondary transfer roller 6 during the secondary transfer, in the case of the intermediate transfer drum 4 in which the voltage generated when the primary transfer roller 5 is subjected to constant current control is V _o , Good transfer is possible if the secondary transfer voltage is controlled to a constant voltage of V _oHi (kV) = 2.0 V _LoAve +1.0, but the actual resistance value of the intermediate transfer drum 4 differs by V _1Ave / V _o. Therefore, the control unit 32 actually determines the secondary transfer voltage determined by V _Hi (kV) = (2.0V _{LoAve +} 1.0) × (V _1Ave / V _o ). It is controlled and applied to the secondary transfer roller 6. The relationship of each voltage at this time is shown in FIG. V _o as the reference voltage is set from the initial.

By carrying out such a configuration and control as described above,
Even when the resistance value of the intermediate transfer drum 4 as the intermediate transfer member is different in the circumferential direction, the secondary transfer can be performed with an appropriate current value, and a good image can be obtained.

<Second Embodiment> (FIG. 3) The schematic structure of the image forming apparatus is the same as that of the first embodiment shown in FIG.

This embodiment also prevents image defects due to uneven resistance values in the circumferential direction of the intermediate transfer drum 4, and forms a toner image on the photosensitive drum 1 as in the apparatus of the first embodiment. It is primary-transferred onto the intermediate transfer drum 4 under constant current control of 3 μA.

The voltage generated at this time is detected by the voltage detection unit 31, and the voltage for one round of the intermediate transfer drum is sampled every 10 msec from the reference point 7 of the intermediate transfer drum 4 (interval of 0.6 mm in length). The value is stored as V _{1 in} the memory of the control unit 32 in order. This voltage fluctuation corresponds to the uneven resistance value in the circumferential direction of the intermediate transfer drum 4.

At the time of primary transfer, the secondary transfer roller 6 is separated from the intermediate transfer drum 4 and brought into contact with the metal roller 9 in the same manner as in Example 1 to perform constant current control, and the average voltage V _LoAve (at that time) kV) is stored in the memory of the control unit 32.

Here, in the case of the intermediate transfer drum 4 in which the voltage generated when the primary transfer roller 5 is subjected to constant current control is Vo, the secondary transfer voltage is _VoHi (kV) = 2.0V _LoAve. It can be set to +1.0, but if the intermediate transfer drum 4 has a circumferential unevenness of the resistance value, V ₁ / V _o at each point of 0.6 mm.
A better transfer can be obtained by proofreading.

Therefore, at the time of the secondary transfer, the control unit 32 sequentially reads the voltage values stored in the memory, and the variable power source 3
Then, the voltage obtained by V _Hi (kV) = (2.0 V _{LoAve +} 1.0) × (V ₁ / V _o ) is sequentially applied to the secondary transfer roller 6 by 10 msec to perform the secondary transfer. To do. The relationship of each voltage at this time is shown in FIG.

By using the configuration and control as in the present embodiment, it is possible to prevent image defects due to uneven resistance values in the circumferential direction of the intermediate transfer drum 4 as an intermediate transfer member.

<Embodiment 3> (FIG. 4) FIG. 4 is a schematic configuration diagram of an image forming apparatus of the present embodiment. The same components and parts as those of the apparatus shown in FIG. 1 are designated by the same reference numerals, and the repeated description will be omitted.

In this embodiment, an image defect caused by the uneven resistance value in the circumferential direction of the secondary transfer roller 6 as the second transfer means is prevented.

In the apparatus of this embodiment, as in the apparatus of the first embodiment, a toner image is formed on the photosensitive drum 1 and the toner image is primary-transferred onto the intermediate transfer drum 4 under the constant current control of 3 μA.

Between the primary transfer of the toner image of the first color and the primary transfer of the toner image of the second color, the secondary transfer roller 6 which is separated from the intermediate transfer drum 6 and abuts on the metal roller 9. Constant current control in the same manner as in Example 1, at that time,
The voltage V _Lo (kV) for one round of the secondary transfer roller is sequentially supplied to the control unit (C) every 10 msec from the reference point of the secondary transfer roller 6.
PU) 32 memory. This voltage fluctuation corresponds to the uneven resistance value of the secondary transfer roller 6 in the circumferential direction.

At the time of secondary transfer, the control unit 32 sequentially reads the voltage values stored in the memory in consideration of the circumferential unevenness of the secondary transfer roller 6, and controls the variable power source 34 to obtain V _Hi (kV) = The voltage obtained by (2.0V _Lo +1.0) is applied to the secondary transfer roller 6 by 10 msec.
To perform secondary transfer.

By using the configuration and control as in the present embodiment, it is possible to prevent image defects due to the uneven resistance value of the secondary transfer roller 6 in the circumferential direction.

<Embodiment 4> (FIG. 5) FIG. 5 is a schematic configuration diagram of an image forming apparatus of the present embodiment. The same components and parts as those of the apparatus shown in FIG. 1 are designated by the same reference numerals, and the repeated description will be omitted.

Also in this embodiment, the image defect caused by the uneven resistance value of the secondary transfer roller 6 as the second transfer means in the circumferential direction is prevented.

In the present embodiment, the intermediate transfer drum 4 has a conductive portion 13 on a part of its outer circumference over a range longer than the outer circumference length of 62.8 mm of the secondary transfer roller 6. In the drawing of FIG. 5, the peripheral length of the secondary transfer roller and the length of the conductive portion 13 are not shown in correspondence with each other.

The secondary transfer roller 6 has a reference position like the intermediate transfer drum 4.

In the apparatus of this embodiment, as in the apparatus of the first embodiment, a toner image is formed on the photosensitive drum 1, and the toner image is primarily transferred onto the intermediate transfer drum 4 under the constant current control of 3 μA. The average value V _1Ave of the voltage at that time is stored in the memory of the control unit 32. At this time, the end portion 7 of the conductive portion 13 of the intermediate transfer drum 4 is used as a reference point for alignment of the intermediate transfer drum, and the reference point 7 is moved from the primary transfer portion T1 by a predetermined distance from the first color. The toner images of the fourth color are sequentially superposed on the intermediate transfer drum 4 and primarily transferred.

When the secondary transfer roller 6 contacts the conductive portion 13 of the intermediate transfer drum 4 between the primary transfer of the first color toner image and the primary transfer of the second color toner image, 2 The secondary transfer roller 6 is subjected to constant current control, the voltage V _Lo is sampled for one round of the secondary transfer roller every 10 msec from the reference position of the secondary transfer roller, and the value is stored in the memory of the controller 32.

At the time of the secondary transfer, the transfer material P is adjusted so that the leading ends of the intermediate transfer drum 4 and the secondary transfer roller 6 are aligned with each other.
Is conveyed to the secondary transfer portion T2 and the image on the intermediate transfer drum 4 is secondarily transferred onto the transfer material P, in consideration of the resistance value of the intermediate transfer drum 4 and the circumferential unevenness of the secondary transfer roller 6, The control unit 32 reads out the voltage stored in the memory, controls the variable power source 34, and obtains the voltage obtained by V _Hi (kV) = (2.0 V _Lo +1.0) × (V _1Ave / V _o ). Secondary transfer is performed by sequentially applying to the secondary transfer roller 6 every 10 msec.

By using such a configuration and control as described above, it is possible to prevent the image from being disturbed due to the uneven resistance value of the secondary transfer roller 6 in the circumferential direction.

<Fifth Embodiment> (FIG. 6) The schematic structure of the image forming apparatus is the same as that of the first embodiment shown in FIG.

In this embodiment, the intermediate transfer drum 4 as the intermediate transfer member and the secondary transfer roller 6 as the second transfer means.
The image defect caused by the uneven resistance in the circumferential direction is prevented.

In this embodiment, the outer peripheral length of the intermediate transfer drum 4 is an integer multiple of the outer peripheral length of the secondary transfer roller 6. Here, the outer peripheral length of the intermediate transfer drum is 3
The outer diameter of the secondary transfer roller 6 was 14 mm, the outer diameter was 6 mm, and the outer diameter of the secondary transfer roller 6 was 6 mm.

Similar to the apparatus of the second embodiment, the intermediate transfer drum 4 is subjected to constant current control at 3 μA at the time of primary transfer, and the voltage value V ₁ (kV) is equivalent to one cycle of the intermediate transfer drum every 10 msec from the reference point 7. Is detected and stored in the memory of the control unit 32.

Further, as in the third embodiment, the secondary transfer roller 6 separated from the intermediate transfer drum 4 at the time of primary transfer.
Is rotated while being in contact with the conductive roller 9, and constant current control is performed with the same current value as in the primary transfer, and the voltage value V _{Lo for} one round of the secondary transfer roller is set every 10 msec from the reference point of the secondary transfer roller 6. (KV) is stored in the memory of the control unit 32.

At the time of the secondary transfer, the control section 32 reads out the voltage stored in the memory in order to take into consideration the resistance value unevenness of both the intermediate transfer drum 4 and the secondary transfer roller 6 in the circumferential direction, and the variable power source 34. Is controlled to apply a voltage determined by V _Hi (kV) = (1.5V _Lo +1.0) × (V ₁ / V _o ) to the secondary transfer roller 6 to transfer the toner image on the intermediate transfer drum 4. Secondary transfer is performed on the material P. The transfer material P is sent to the fixing device 12 to obtain an output image. The relationship of each voltage at this time is shown in FIG.

By using the configuration and control as in this embodiment, it is possible to obtain a good transferred image without being influenced by the fluctuation of the resistance value of the intermediate transfer drum 4 and the secondary transfer roller 6 in the circumferential direction. became.

[0073]

As described above, according to the present invention, there is provided means for forming an image on the image carrier, and the image formed on the image carrier is first transferred onto the intermediate transfer member. After the primary transfer by the transfer means of, the image on the intermediate transfer member,
Regarding an image forming apparatus for performing secondary transfer on a transfer material by using a second transfer means facing the intermediate transfer body, the image forming apparatus is not affected by the uneven resistance value in the circumferential direction of the intermediate transfer body or the second transfer means. An excellent image can be formed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first exemplary embodiment (second exemplary embodiment / fifth exemplary embodiment).

FIG. 2 is a relationship diagram of each potential in Example 1.

FIG. 3 is a relational diagram of potentials in Example 2.

FIG. 4 is a schematic configuration diagram of an image forming apparatus according to a third embodiment.

FIG. 5 is a schematic configuration diagram of an image forming apparatus according to a fourth embodiment.

FIG. 6 is a relational diagram of potentials in Example 5.

[Explanation of symbols]

 1 Photoreceptor Drum as First Image Carrier 2 Primary Charger 3 Exposure Light 4 Intermediate Transfer Drum as Intermediate Transfer Body 5 Primary Transfer Roller as First Transfer Means 6 Secondary as Second Transfer Means Transfer roller 7 Perimeter reference point of intermediate transfer drum 8 Cleaning device for photosensitive drum 9 Conductive roller 10 Cleaning device for intermediate transfer drum 11 (M, C, Y, BK) Color toner developing device 12 Fixing device P Second image Transfer material as carrier

Claims (7)

[Claims] 1. A means for forming an image on an image carrier, wherein the image formed on the image carrier is primarily transferred onto an intermediate transfer body by a first transfer means, and then the intermediate transfer is carried out. In an image forming apparatus that secondarily transfers an image on a body onto a transfer material by using a second transfer unit facing an intermediate transfer body, the primary transfer is performed by a predetermined constant current control, and a voltage generated there An image forming apparatus comprising: a storage unit for storing the transfer voltage; and a unit for determining a transfer voltage at the time of the secondary transfer based on the voltage value. 2. The image forming apparatus according to claim 1, wherein the voltage stored during the primary transfer is an average value of the voltages detected during the constant current control. 3. The image according to claim 1, wherein the voltage stored during the primary transfer corresponds to the detected voltage during the constant current control with the circumferential position of the intermediate transfer member. Forming equipment. 4. A means for forming an image on an image carrier, the image formed on the image carrier being primarily transferred onto an intermediate transfer body by a first transfer means, and then the intermediate transfer. In an image forming apparatus for secondarily transferring an image on a body onto a transfer material by using a second transfer means facing an intermediate transfer body, a voltage value when the second transfer means is subjected to constant current control is Two
2. An image forming apparatus comprising: a means for storing the transfer means in association with the circumferential position of the transfer means; and a means for determining the transfer voltage at the secondary transfer based on the voltage value. 5. The image forming apparatus according to claim 4, wherein a part of the intermediate transfer member is made conductive, and the second transfer means is brought into contact with the part to perform constant current control. 6. The image forming apparatus according to claim 4, wherein the second transfer unit is capable of coming into contact with and separating from the intermediate transfer member, and comes into contact with the conductive member at the time of separation to perform constant current control. . 7. The image forming apparatus according to claim 1, wherein the second transfer unit is a transfer roller.