JP2001331046A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device by which an image having an excellent quality is formed by preventing the occurrence of insufficient transfer and a print image due to the change of the inner surface resistance value of an intermediate transfer body to whose primary or secondary transfer means a constant electric charge is supplied by a constant current supplying means. SOLUTION: This device is composed of the intermediate transfer body 2 turning while it is opposed to the toner image carrying surface 1a of an image carrier 1, the primary transfer means 3 performing primary transfer to the intermediate transfer body 2, the secondary transfer means 4 performing secondary transfer to a body to be transferred (P), the constant current supplying means 5 to supply the primary transfer means 3 or the secondary transfer means 4 with a constant current, a grounding means 6 to ground both sides of an entrance to go in and out of the transfer bias applying part (T) of a turning intermediate transfer body 2 and a leaked current detecting/replenishing means 7 to replenish a shunt current by detecting a current value meaning a flowing leaked current to the grounding means 6 and feeding back to the constant current supplying means 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a copying machine, a facsimile machine, and the like, which form an image by intermediately transferring a toner image formed on an image carrier.
The present invention relates to an image forming apparatus such as a printer or a multifunction peripheral thereof.

[0002]

2. Description of the Related Art In a conventional image forming apparatus, when a toner image formed on a drum-shaped or endless-shaped photosensitive member as an image carrier is transferred to a transfer paper as an object to be transferred, an image is formed. The electrostatic latent image formed on the photoconductor is converted into a toner image by a developing device. In a color copying machine, a color printer, and the like, black (Black), cyan (Cya)
n), magenta (Magenta), yellow (Yel)
low), the formed color toner image is sequentially primary-transferred to the intermediate transfer belt of the intermediate transfer body by the primary transfer charge applying means, and sequentially primary-transferred to the intermediate transfer belt. The transferred color toner image is secondarily transferred to a transfer receiving body by a secondary transfer charge applying means, and the transfer receiving body on which the color toner image is secondarily transferred is fixed by a fixing means, whereby a series of image forming steps is performed. A conventional example in which the processing is terminated is known (see Japanese Patent Application Laid-Open No. 11-84894). In the primary transfer in a series of image forming steps in such an image forming apparatus, both a solid image and a halftone image are well transferred, but the initial resistance value of the intermediate transfer belt of the intermediate transfer member varies, and environmental fluctuations cause the transfer. Good transfer due to a change in the initial resistance value of the intermediate transfer belt as an intermediate transfer member, a change in the resistance of the intermediate transfer belt with the passage of time, the potential of the drum-shaped or non-terminal shaped photoconductor, and the Q / M of the toner used. Was sometimes impaired. Therefore, a constant current power supply using a constant current method in which a constant charge is supplied to the transfer unit without being influenced by the above-mentioned fluctuation factors is used. However, in the constant current method of the constant current power supply in which a constant charge is supplied to the transfer unit, if the inner surface resistance of the intermediate transfer belt is low, current flows to the drum-shaped or endless-shaped photoconductor at the same time. A large amount of current also flows into the nearby ground roller, and the total current is constant and the resistance value decreases, resulting in an abnormal image such as insufficient transfer, undesired scattering of toner, and unfavorable spots such as a print image. Image quality has deteriorated. Therefore, in these conventional image forming apparatuses, in a series of image forming processes, in a constant current method of a constant current power supply in which a constant charge is supplied to a transfer unit, if the inner surface resistance value of the intermediate transfer belt is low, At the same time as the current flows through the body, a large amount of current also flows into the nearby ground roller, etc., and the total current is constant and the resistance value decreases, resulting in insufficient transfer, undesired scattering of toner, unfavorable spots on print images, etc. There has been a problem that the quality of the formed image is deteriorated due to the occurrence of the abnormal image.

[0003]

An object of the present invention is to solve such a problem. In other words, a constant charge is supplied to the primary or secondary transfer unit by the constant current supply unit. An object of the present invention is to provide an image forming apparatus in which a high-quality image is formed by preventing generation of an image.

[0004]

According to one aspect of the present invention, there is provided an image forming apparatus for forming an image by intermediately transferring a toner image formed on an image carrier. An image carrier that rotates while supporting a toner image, an intermediate transfer member that rotates in opposition to the toner image carrying surface of the image carrier, and an image carrier that carries the toner image on the intermediate transfer member. The toner image formed on the surface is
A primary transfer unit for performing a secondary transfer, a secondary transfer unit for performing a secondary transfer of a toner image primarily transferred to the intermediate transfer body by the primary transfer unit to a transfer target body, the primary transfer unit or the secondary transfer unit Constant current supply means for supplying a constant current to the next transfer means,
The constant current supplied from the constant current supply means applies the transfer bias to the intermediate transfer body on which the primary transfer means or the secondary transfer means rotates. A leakage means for detecting a current value at which a leakage current flows into an entrance-side grounding member on the entrance side of the grounding means or an exit-side grounding member on the exit side, and feeds back the current to the constant current supply means to supplement the divided current. The main feature of the present invention is that the image forming apparatus includes a current detection and supplementing unit. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the intermediate transfer body is rotated by stretching the intermediate endless transfer belt formed of an endless belt and the intermediate endless transfer belt. The main feature of the present invention is that the image forming apparatus includes a driving roller to be driven, and a driven roller that rotates along with the intermediate non-terminal transfer belt by stretching the driving roller. According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the entrance-side grounding member or the exit-side grounding member of the grounding means comprises an entrance-side grounding roller or an outlet-side grounding roller. The main feature is that there is.

[0005] The present invention of claim 4 is the invention of claim 1, 2 or 3
In the image forming apparatus described in the above, the main feature is that the entrance-side ground member or the outlet-side ground member of the grounding means is an image forming apparatus that also serves as a drive roller that stretches and drives the intermediate transfer body. I do. The present invention of claim 5 is based on claim 1,
5. The image forming apparatus according to 2, 3, or 4, wherein the entrance-side grounding member or the exit-side grounding member of the grounding means is an image forming apparatus also serving as a driven roller that stretches and follows the intermediate transfer member. Is the main feature. According to a sixth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, or fifth aspect, the entrance-side grounding member or the outlet-side grounding member of the grounding unit is tensioned by stretching an intermediate transfer member. The main feature is that the image forming apparatus is also used as a tension roller for urging the image. The present invention according to claim 7 is based on claim 1,
7. The image forming apparatus according to 2, 3, 5, or 6, wherein the entrance-side grounding member or the exit-side grounding member of the grounding means is an image forming device including an entrance-side conductive grounding brush or an exit-side conductive grounding brush. Is the main feature. According to an eighth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, or sixth aspect, the entrance-side grounding member or the exit-side grounding member of the grounding means is an entrance-side ground metal plate or an exit-side grounding member. The main feature is that the image forming apparatus is made of a sheet metal. According to a ninth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, sixth, or seventh aspect, the entrance-side grounding member or the exit-side grounding member of the grounding means includes an entrance-side conductive ground. The main feature is that the image forming apparatus is a film or an outlet-side conductive ground film. According to a tenth aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, sixth, seventh, or eighth aspect, the entrance-side grounding member or the outlet-side grounding member of the grounding means has an intermediate endless terminal. The main feature is that the image forming apparatus is in contact with the inner surface side of the transfer belt. The invention according to claim 11 is the invention according to claims 1, 2, 3, 4,
In the image forming apparatus described in 5, 6, 7, 8 or 9,
The main feature of the image forming apparatus is that the resistance value of the grounding means is 10 ⁸ Ω or less.

The present invention according to claim 12 is based on claims 1, 2,
In the image forming apparatus described in 3, 4, 5, 6, 7, 8, 9 or 10, the inner surface resistivity of the inner surface of the intermediate transfer body is determined by a surface resistance measuring device “Yuika Denshi Co., Ltd.” The main feature is that the image forming apparatus has a measurement value of 10 ⁷ Ω / □ to 10 ¹⁰ Ω / □ by “Hirester”. Claim 1
The third aspect of the present invention relates to claims 1, 2, 3, 4, 5, 6, 7,
The image forming apparatus according to 8, 9, 10 or 11,
The distance between the transfer bias applying unit that applies a transfer bias to the intermediate transfer body in the primary transfer unit or the secondary transfer unit and the entrance-side ground member that is disposed on the entrance side and grounds is determined by the primary transfer unit or the above-described primary transfer unit. The main feature is that the image forming apparatus is shorter than the distance between a transfer bias applying unit that applies a transfer bias to the intermediate transfer body in the secondary transfer unit and an outlet-side grounding member that is disposed on the outlet side and grounds. Features. The invention according to claim 14 is the invention according to claims 1, 2, 3,
In the image forming apparatus described in 4, 5, 6, 7, 8, 9, 10, 11, or 12, an entrance is provided from a transfer bias applying unit for applying a transfer bias to an intermediate transfer body in a primary transfer unit or a secondary transfer unit. The resistance value between the first transfer means and the second transfer means is set between the first transfer means and the second transfer means.
The image forming apparatus mainly has a resistance higher than a resistance value between a transfer bias applying unit for applying a transfer bias to the intermediate transfer body in the next transfer unit and an outlet side grounding unit arranged on the outlet side and grounded. Features.

[0007]

According to the first aspect of the present invention, there is provided an image forming apparatus comprising: an intermediate transfer unit configured to support a toner image to be formed; Primary transfer means for primary transfer of the toner image formed on the toner image bearing surface of the image carrier to the body, and secondary transfer of the toner image primary-transferred to the intermediate transfer body by the primary transfer means to the transfer-receiving body A transfer bias applying unit that applies a transfer bias to an intermediate transfer member on which the primary transfer unit or the secondary transfer unit rotates by using a constant current supplied from a constant current supply unit that supplies a constant current to the secondary transfer unit that performs transfer; The leakage current flows into the entrance-side grounding member on the entrance side of the grounding means or the exit-side grounding member on the exit side of the grounding means for grounding both sides of the entrance to and exit from the entrance and exit. To the constant current supply means. And supplemented with partial current and back so as to form an image, constant charge with a constant current supply means 1
It is possible to provide an image forming apparatus that forms a high-quality image by preventing occurrence of insufficient transfer due to a change in an inner surface resistance value of an intermediate transfer member supplied to a secondary transfer unit or a secondary transfer unit. . The toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member that rotates in opposition to the toner image bearing surface of the image carrier that rotates while bearing the toner image to be formed A constant current for supplying a constant current to a primary transfer unit for primary transfer of an image and a secondary transfer unit for secondary transfer of a toner image primarily transferred to an intermediate transfer body by the primary transfer unit to a transfer receiving body. An inlet side of a grounding unit that grounds both sides of an entrance and an exit that enter and exit a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a constant current supplied from a supply unit. The leakage current flowing into the inlet-side grounding member or the outlet-side grounding member of the outlet is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supplying means to supplement the divided current. The intermediate transfer member is An intermediate endless transfer belt consisting of an endless belt, a drive roller that stretches and rotates the intermediate endless transfer belt, and a driven roller that stretches the intermediate endless transfer belt together with the drive roller and is driven to rotate. An image is formed, and with a simple structure, constant charge is supplied by a constant current supply unit to a primary transfer unit or a secondary transfer unit. It is possible to provide an image forming apparatus in which a high-quality image is formed by preventing such an image.

According to a third aspect of the present invention, an intermediate transfer member which rotates while facing the toner image bearing surface of the image bearing member which rotates while bearing the toner image to be formed is formed on the toner image bearing surface of the image bearing member. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill The grounding member on the inlet side or the grounding member on the outlet side of the ground means is used as the grounding roller on the inlet side or the grounding roller on the outlet side so as to form an image. The present invention can provide an image forming apparatus capable of forming a high-quality image by preventing insufficient transfer due to a change in the inner surface resistance of an intermediate transfer member supplied to the image forming apparatus. The toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member that rotates in opposition to the toner image bearing surface of the image carrier that carries the toner image to be formed and rotates. Primary transfer means for primary transfer of the image, and secondary transfer of the toner image primarily transferred to the intermediate transfer body by the primary transfer means to the transfer receiving body.
The primary transfer unit or the secondary transfer unit enters and exits a transfer bias application unit that applies a transfer bias to the rotating intermediate transfer body with a constant current supplied from a constant current supply unit that supplies a constant current to the next transfer unit. The leakage current is detected by the leakage current detecting and supplementing means when the leakage current flows into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side of the grounding means that grounds both sides of the entrance and exit, and the detected current value is a constant current. The supply current is fed back to supplement the current, and the entrance-side grounding member or the exit-side grounding member of the grounding unit is also used as a driving roller that stretches and drives the intermediate transfer member to form an image. A constant charge is supplied to the primary transfer unit or the secondary transfer unit by the current supply unit, thereby preventing the occurrence of insufficient transfer due to a change in the inner surface resistance of the intermediate transfer body, thereby forming a high quality image at low cost. Image forming equipment That there is to be able to provide. The toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member rotating opposite to the toner image bearing surface of the image carrier rotating carrying the toner image to be formed. Primary transfer means for primary transferring an image;
The primary transfer is performed by a constant current supplied from a constant current supply unit that supplies a constant current to a secondary transfer unit that secondary-transfers the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to the transfer target body. Means or a secondary transfer means for applying a transfer bias to the rotating intermediate transfer member. A transfer bias application unit for applying a transfer bias. A leakage current flowing into the member is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to supplement the current, and an inlet-side grounding member or an outlet-side grounding member of the grounding means. Is also used as a driven roller that is stretched and driven by an intermediate transfer member, so that a constant charge is supplied to the primary transfer unit or the secondary transfer unit by a constant current supply unit. Inner resistance of To prevent the occurrence of lack of transcription by changing a higher quality image is formed to be able to provide an image forming apparatus low-cost.

According to a sixth aspect of the present invention, an intermediate transfer member which rotates while facing the toner image bearing surface of the image bearing member which rotates to support the toner image to be formed is formed on the toner image bearing surface of the image bearing member. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill The ground contact member on the inlet side or the ground member on the outlet side of the ground means is also used as a tension roller that stretches the intermediate transfer member and urges the tension, so that an image is formed. Next transfer means or 2
It is possible to provide a lower cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance of an intermediate transfer member supplied to a next transfer unit and forming a high quality image. 8. The toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member that rotates in opposition to the toner image bearing surface of the image carrier that rotates while bearing the toner image to be formed. A constant current for supplying a constant current to a primary transfer unit for primary transfer of an image and a secondary transfer unit for secondary transfer of a toner image primarily transferred to an intermediate transfer body by the primary transfer unit to a transfer receiving body. An inlet side of a grounding unit that grounds both sides of an entrance and an exit that enter and exit a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a constant current supplied from a supply unit. The leakage current flowing into the inlet-side grounding member or the outlet-side grounding member of the outlet is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supplying means to supplement the divided current. Grounding means A constant charge is supplied to the primary transfer means or the secondary transfer means by the constant current supply means such that the side ground member or the outlet ground member is formed as an entrance conductive ground brush or an exit conductive ground brush. It is possible to provide a lower-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance of a supplied intermediate transfer body and forming a high-quality image.

According to another aspect of the present invention, an intermediate transfer member which rotates to face a toner image bearing surface of an image bearing member which rotates while bearing a toner image to be formed is formed on the toner image bearing surface of the image bearing member. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill A constant charge is supplied to the primary transfer unit or the secondary transfer unit by the constant current supply unit so that an image is formed by using the entrance side ground member or the exit side ground member of the ground means as the entrance side ground plate or the exit side ground plate. It is possible to provide a lower-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance of a supplied intermediate transfer body and forming a high-quality image. The toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member rotating opposite to the toner image bearing surface of the image bearing member carrying the toner image to be formed and rotating A constant current for supplying a constant current to a primary transfer unit for primary transfer of an image and a secondary transfer unit for secondary transfer of a toner image primarily transferred to an intermediate transfer body by the primary transfer unit to a transfer receiving body. An inlet side of a grounding unit that grounds both sides of an entrance and an exit that enter and exit a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a constant current supplied from a supply unit. The leakage current flowing into the inlet-side grounding member or the outlet-side grounding member of the outlet is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supplying means to supplement the divided current. Grounding means A constant charge is supplied to the primary transfer means or the secondary transfer means by the constant current supply means so that an image is formed as the side ground member or the outlet ground member as the entrance conductive ground film or the exit conductive ground film. It is possible to provide a lower-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance of a supplied intermediate transfer body and forming a high-quality image.

According to a tenth aspect of the present invention, the toner image forming surface is formed on the intermediate transfer member which rotates while facing the toner image bearing surface of the image bearing member which rotates while carrying the toner image to be formed. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit to and from a transfer bias applying unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the inlet side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. When you refill The inlet-side grounding member or the outlet-side grounding member of the grounding means comes into contact with the inner surface side of the intermediate endless transfer belt to form an image, reliably grounds without adversely affecting the formed image, and supplies a constant current. The present invention provides an image forming apparatus that forms a high-quality image by preventing occurrence of insufficient transfer due to a change in the inner surface resistance of an intermediate transfer body in which a constant charge is supplied to a primary transfer unit or a secondary transfer unit. To be able to 12. The toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member that rotates in opposition to the toner image bearing surface of the image carrier that rotates while carrying the toner image to be formed. A primary transfer means for primary transferring an image, and a primary transfer means
The primary transfer unit or the secondary transfer unit is rotated by a constant current supplied from a constant current supply unit that supplies a constant current to a secondary transfer unit that secondary-transfers the next-transferred toner image to a transfer target body. A resistance value that grounds both sides of an entrance and exit that enters and exits a transfer bias application unit that applies a transfer bias to the intermediate transfer body is 10 ⁸
The leakage current flowing into the inlet-side grounding member on the inlet side of the grounding means or the outlet-side grounding member on the outlet side is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supply means. To form an image by replenishing the divided current to ensure reliable grounding, and a constant current supply means to supply a constant charge to the primary transfer means or the secondary transfer means. It is possible to provide an image forming apparatus that forms a high-quality image by preventing occurrence of insufficient transfer due to a change in resistance value.

According to a twelfth aspect of the present invention, an intermediate transfer member which rotates while facing the toner image bearing surface of the image bearing member which bears and rotates the toner image to be formed is formed on the toner image bearing surface of the image bearing member. Primary transfer means for primary transfer of the transferred toner image, and an inner surface resistivity of the inner surface by the primary transfer means measured by a surface resistance measuring device “Hirester” manufactured by Yuka Electronics Co., Ltd. ^The toner image primarily transferred to the intermediate transfer member having a resistance of ⁷ Ω / □ to 10 ¹⁰ Ω / □ is
Transfer bias application for applying a transfer bias to an intermediate transfer member on which the primary transfer means or the secondary transfer means rotates with a constant current supplied from the constant current supply means for supplying a constant current to the secondary transfer means for performing the next transfer. The leakage current is detected by the leakage current detecting and supplementing means, and the detected current is detected by the leakage current flowing into the entrance-side grounding member on the entrance side of the grounding means or the exit-side grounding member on the exit side of the grounding means that grounds both sides of the entrance to and exit from the section. The value is fed back to the constant current supply means so that the current is replenished to form an image so that the image is formed. Thus, the grounding is reliably performed, and a constant charge is supplied to the primary transfer means or the secondary transfer means by the constant current supply means. It is possible to provide an image forming apparatus that can form a high-quality image by preventing occurrence of insufficient transfer due to a change in an inner surface resistance of a supplied intermediate transfer member. 14. The toner formed on the toner image bearing surface of the image carrier on an intermediate transfer member that rotates to face the toner image bearing surface of the image carrier that rotates to carry the toner image to be formed. A constant current for supplying a constant current to a primary transfer unit for primary transfer of an image and a secondary transfer unit for secondary transfer of a toner image primarily transferred to an intermediate transfer body by the primary transfer unit to a transfer receiving body. An inlet side of a grounding unit that grounds both sides of an entrance and an exit that enter and exit a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a constant current supplied from a supply unit. The leakage current flowing into the inlet-side grounding member or the outlet-side grounding member of the outlet is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supplying means to supplement the divided current. Primary transfer hand Or 2
The distance between the transfer bias applying unit for applying a transfer bias to the intermediate transfer body in the next transfer unit and the entrance side ground member disposed on the entrance side and grounded is the intermediate transfer described in the primary transfer unit or the secondary transfer unit. The transfer bias is applied to the body from the transfer bias applying unit is disposed on the outlet side and is shorter than the distance between the outlet side grounding member that is grounded so that an image is formed. The electric field at the flow inlet side is reduced to prevent undesired pre-transfer due to the movement of the toner before transfer, and the inner surface of the intermediate transfer body in which a constant charge is supplied to the primary transfer means or the secondary transfer means by the constant current supply means. It is possible to provide an image forming apparatus that can form a high-quality image by preventing the occurrence of abnormal images such as insufficient transfer, undesirable scattering of toner, and unfavorable spots on a print image due to a change in resistance value. To.

According to a fourteenth aspect of the present invention, an intermediate transfer member which rotates to face the toner image bearing surface of the image bearing member which rotates while supporting the toner image to be formed is formed on the toner image bearing surface of the image bearing member. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the inlet side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. When you refill The resistance value between the transfer bias applying unit that applies a transfer bias to the intermediate transfer body in the primary transfer unit or the secondary transfer unit and the entrance side grounding unit that is disposed on the entrance side and grounded is the primary transfer unit or the secondary transfer unit. A transfer bias is applied to the intermediate transfer body in the transfer unit from the transfer bias application unit, which is disposed on the outlet side from the transfer bias application unit, and is higher than a resistance value between the transfer unit and the outlet side grounding unit that is grounded to form an image. Leakage current flows to the side to reduce the electric field on the entrance side, preventing undesired pre-transfer due to toner movement before transfer, and a constant charge is supplied to the primary transfer means or the secondary transfer means by the constant current supply means. Image forming apparatus that forms a high-quality image by preventing insufficient transfer due to a change in the inner surface resistance value of the intermediate transfer member, undesired scattering of toner, and occurrence of an abnormal image such as an undesired spot print image Oda to provide is to be able to.

[0014]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall schematic configuration diagram of an example of an image forming apparatus to which the present invention is applied, and FIG. 2 is a configuration diagram of main parts of FIG. The image forming apparatus 0 of the present invention includes an image forming unit 100, a color image reading unit 200, a sheet feeding unit 300,
And a control unit 400 for driving and controlling them. The color image reading unit 200 converts the color image information of the original (O) into, for example, red, green,
It is read for each blue color separation light and converted into an electrical image signal. Then, based on the intensity levels of the red, green, and blue color separation image signals obtained by the color image reading unit 200, a color conversion process is performed by an image processing unit (not shown), and black (Black), cyan (Cyan) ,
Magenta, Yellow
w) image data is obtained. The image forming unit 100 includes a drum-shaped photoconductor as the image carrier 1,
A charging charger as a charging unit 8, a cleaning blade 9a and a fur brush 9b as a cleaning unit 9, a writing optical unit as an exposure unit 10, a revolver developing unit as a developing unit 11, an intermediate transfer body 2, a primary transfer unit 3, The image forming apparatus includes a secondary transfer unit 4 and a pair of fixing rollers as the fixing unit 12. Photoconductor 1
Rotates counterclockwise in the direction of arrow A in the figure, and surrounds the charger 8, the cleaning blade 9a and the fur brush 9b, the revolver developing unit 11, and the intermediate endless transfer belt 2a as the intermediate transfer body 2. And so on. The writing optical unit of the exposure unit 10 includes:
The color image data from the color image reading unit 200 is converted into an optical signal, and the laser light L corresponding to the image of the document is irradiated onto the toner image carrying surface 1 a of the photoconductor 1 uniformly charged by the charging charger 8. To do optical writing,
An electrostatic latent image is formed on the surface of the toner image carrying surface 1a of the photoconductor 1. The writing optical unit of the exposure unit 10 can be constituted by, for example, a semiconductor laser as a light source, a laser emission drive control unit, a polygon mirror and its rotation motor, an f / θ lens, a reflection mirror, and the like. The revolver developing unit of the developing means 11 is a black (Bl
ack) black developing device 11a using toner, cyan (Cyan) using cyan toner
yan) developing machine 11b, magenta (Magenta) developing machine 11 using magenta toner
c, a yellow (Yellow) developing machine using yellow toner, a developing revolver driving unit 11e for rotating the entire unit counterclockwise, and the like.

Each of the black developing unit 11a, cyan developing unit 11b, magenta developing unit 11c, and yellow developing unit 11d installed in the revolver developing unit 11 uses the photoreceptor 1 for developing a developer spike to develop an electrostatic latent image. A developing sleeve (not shown) as a developer carrying member that rotates in contact with the surface of the toner image carrying surface 1a, a developer paddle (not shown) that rotates to pump up and agitate the developer, and a developing sleeve (not shown) It is composed of a developing sleeve drive unit (not shown) that rotates. In this embodiment, the toner in each of the black developing device 11a, the cyan developing device 11b, the magenta developing device 11c, and the yellow developing device 11d is charged to a negative polarity by stirring with the ferrite carrier. A negative DC voltage Vdc (DC component) is converted to an AC voltage Vac (AC component) by a developing bias power source as a developing bias applying unit (not shown).
Are applied, and each developing sleeve (not shown) is biased to a predetermined voltage with respect to the metal base layer of the photoreceptor 1. Image forming apparatus 0 of the present invention
In the standby state of the color copying machine main body, the black developing machine 11a of the revolver developing unit 11 is stopped at the home position located at the developing position, and when the copy start key is pressed, the original (O) image data is read. , And based on the color image data, optical writing by the laser beam L, that is, formation of each black electrostatic latent image, formation of a cyan electrostatic latent image, formation of a magenta electrostatic latent image, and formation of a yellow electrostatic latent image are started. In order to enable development from the front end of the black electrostatic latent image, before the front end of the electrostatic latent image reaches the black development position, rotation of a black developing sleeve (not shown) is started to form the black electrostatic latent image. Develop with black toner. Then, the developing operation of the black electrostatic latent image is continued, but when the rear end of the black electrostatic latent image passes the black developing position, the revolver is immediately moved until the developing machine of the next color comes to the developing position. The developing unit 11 rotates. This is completed at least before the leading end of the electrostatic latent image based on the next image data reaches the developing position. The intermediate endless transfer belt (intermediate transfer belt) 2a is made of a semiconductor or an insulator and has a single-layer or multi-layer structure.
It is stretched around the driven roller 2c, the tension roller 2d, the cleaning opposing roller 2e, and the like. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller as the primary transfer means 3 is grounded.

Around the intermediate endless transfer belt 2a, 2
A secondary transfer conveyor belt 2f that conveys a transfer sheet of a transfer target (P) on which secondary transfer is performed by a secondary transfer bias roller of the next transfer unit 4 in the direction of arrow C shown in FIG. A transfer bias roller, an intermediate transfer member cleaning blade 2g, a lubricant application brush 2h, and the like are disposed so as to face each other. In a primary transfer section (T1) for primary transfer of the toner image on the toner image carrying surface 1a of the photoconductor 1 to the intermediate endless transfer belt 2a, a primary transfer bias roller as the primary transfer means 3, and a ground. By means 6 (the inlet-side ground roller 6a1 as the inlet-side ground member 6a, the primary inlet-side ground roller 6a11, and the outlet-side ground roller 6b1 as the outlet-side ground member 6b, the primary outlet-side ground roller 6b11), The end transfer belt 2a is stretched so as to be pressed against the toner image holding surface 1a, thereby forming a nip portion having a predetermined width between the toner image holding surface 1a and the intermediate endless transfer belt 2a. The lubricant applying brush 2h polishes the plate-shaped lubricant, zinc stearate 2i, and transfers the polished fine particles to the intermediate endless transfer belt 2a.
Is to be applied. The lubricant application brush 2h is also configured to be adjacent to the intermediate endless transfer belt 2a, and is controlled to contact the intermediate endless transfer belt 2a at a predetermined timing. The primary transfer bias roller, which is the primary transfer unit 3, is supplied with a constant current by the primary transfer constant current supply unit 5a of the constant current supply unit 5, and has a predetermined size according to the number of superimposed toner images. When a transfer bias controlled by current or voltage is applied, the transfer roller 2b bears a toner image to be formed and faces the toner image bearing surface 1a which rotates in the direction of arrow A shown in FIG.
Endless transfer belt 2 of intermediate transfer body 2 rotating in the direction
The primary transfer of the toner image formed on the toner image carrying surface 1a of the photoreceptor 1 to a is performed.

The primary transfer leakage current detecting and supplementing means 7a (the entrance primary transfer leakage current detecting and supplementing means 7a1 or the exit primary transfer leakage current detecting and supplementing means 7a2) as the leakage current detecting and supplementing means 7 is a resistor 7a11 or a resistor 7a21. And a primary transfer bias roller, which is a primary transfer unit 3,
A primary entrance-side ground roller 6 that grounds both sides of an entrance and exit that enters and exits a transfer bias application unit (T1) that applies a transfer bias to the intermediate endless transfer belt 2a of the rotating intermediate transfer body 2.
The current value at which the leakage current flows into a11 or the primary exit side ground roller 6b11 is detected, and the current is supplemented by feeding back to the primary transfer constant current supply means 5a. The intermediate endless transfer belt 2a is in contact with the toner image bearing surface 1a between the primary entrance side ground roller 6a11 and the primary exit side ground roller 6b11. The current flowing through the primary transfer bias roller 3 is transferred to the toner image bearing surface 1a through the intermediate endless transfer belt 2a.
Flow into At this time, depending on the value of the back surface resistance of the intermediate endless transfer belt 2a, a large amount of current is distributed to the primary entrance side ground roller 6a11 and the primary exit side ground roller 6b11 on the exit side, causing loss. In the experiment, the value measured by Yuhi Denshi Co., Ltd.'s surface resistance measuring device “Hirester” was 1 × E9Ω.
If it is less than / □, the current flowing to the primary entrance side ground roller 6a11 and the exit side primary exit side ground roller 6b11 is extremely large. In order to compensate for this, the primary entrance side ground roller 6a11 and the primary exit side ground roller 6b11
Is fed back to the primary transfer constant current supply means 5a to supplement the divided current. The current flowing from the secondary transfer bias roller 4 is divided into an inlet-side ground roller 6a1 (second inlet-side ground roller 6a12) as an inlet-side ground member 6a and an outlet-side ground roller 6b1 (2) as an outlet-side outlet ground member 6b. It is distributed to the next outlet side ground roller 6b12).
Therefore, the current flowing from the secondary transfer bias roller 4 is
It does not affect the primary transfer section (T1) of the primary transfer bias roller 3. However, for example, when the secondary exit side ground roller 6b12 is eliminated, the leakage current flowing from the secondary transfer bias roller 4 flows into the primary entrance side ground roller 6a11 and is fed back. As a result, the primary transfer bias roller 3
The value of the current flowing through the printer becomes high, resulting in insufficient transfer and the occurrence of an abnormal image.

In a secondary transfer section (T2) for secondary-transferring the toner image on the intermediate endless transfer belt 2a to a transfer-receiving member (P), a secondary transfer bias roller as the secondary transfer means 4 includes:
Secondary inlet side ground roller 6a12 and secondary outlet side ground roller 6a12
By pressing the transfer target (P) against the intermediate endless transfer belt 2a stretched around b12 via the secondary transfer conveyance belt 2f, the intermediate endless transfer belt 2a and the secondary transfer bias roller 4 A nip portion having a predetermined width is formed therebetween. The secondary transfer / conveyance belt 2f is stretched over support rollers 2f1, 2f2, and 2f3, and the stretched portion between the support rollers 2f1 and 2f2 is connected to the secondary entrance-side ground roller 6a12 and the secondary exit-side ground. It can be pressed against the roller 6b12. That is, the support roller f1 is supported so as to be able to advance and retreat between the retracted position shown by the chain line and the pressed position shown by the solid line. Three support rollers 2f1, 2
One of f2 and 2f3 is a driving roller which is rotationally driven by a driving unit (not shown), and the driving roller conveys the secondary transfer conveying belt 2f in the direction of arrow C shown in the drawing. The secondary transfer bias roller 4 is supplied with a constant current by a secondary transfer constant current supply unit 5b as a constant current supply unit 5, and is controlled to a predetermined magnitude of current or voltage according to the number of superimposed toner images. The transfer bias applied is applied to the surface of the intermediate endless transfer belt 2a which rotates in the direction of arrow B by the drive roller 2b carrying the primary-transferred toner image. The secondary transfer of the toner image primary-transferred onto the surface of the intermediate endless transfer belt 2a onto the transfer-receiving body (P) conveyed in the direction of arrow C by the following operation. Inlet secondary transfer leakage current detecting and supplementing means 7b1 or outlet secondary transfer leakage current detecting and supplementing means 7b2
Are grounded via the resistor 7b11 or 7b21, and the two sides of the entrance and exit of the secondary transfer bias roller 4 entering and exiting a transfer bias applying unit (T2) for applying a transfer bias to the rotating intermediate endless transfer belt 2a. The secondary transfer constant current is detected by detecting a current value at which a leakage current flows into the secondary entrance-side ground roller 6a12 of the entrance-side ground roller 6a1 of the entrance-side ground member 6a or the secondary exit-side ground roller 6b12 of the exit side. The current is supplemented by feeding back to the supply means 5b.
Secondary transfer bias roller 4 and secondary transfer conveyance belt 2f
The supporting roller 2f1 and the secondary transfer bias roller 4 are moved in the direction indicated by arrow D in the drawing so that the supporting roller 2f1 and the secondary transfer bias roller 4 can take a position where they come into pressure contact with the secondary entrance-side ground roller 6a12 and the secondary exit-side ground roller 6b12. Is provided with a separation / contact mechanism (not shown) that is driven. The secondary transfer bias roller 4, the secondary transfer transport belt 2f and the support roller 2f1 at the separated position are indicated by a two-dot chain line.

The registration roller pair 13 is formed of the intermediate endless transfer belt 2a and the secondary transfer conveyance belt 2f sandwiched between the secondary transfer bias roller 4, the secondary entrance side ground roller 6a12, and the secondary exit side ground roller 6b12. In the meantime, the transfer target (P) is fed at a predetermined timing. Secondary transfer conveyor belt 2
f denotes a portion of the fixing means 12 which is stretched around the support roller 2f2, and a charge removing charger 14 for removing charge from the transfer object (P) and a charge removing charger 15 for removing charge from the secondary transfer conveyance belt 2f are opposed to each other. It is arranged. A cleaning blade 16 is in contact with a portion of the secondary transfer / conveying belt 2f which is stretched around a lower supporting roller 2f3 in the drawing. The static elimination charger 14 removes the charge held on the transfer object (P), and thereby transfers the transfer object (P) to the secondary transfer belt 2 with the strength of the transfer object (P) itself.
This makes it possible to separate well from f. The charge removing charger 15 removes charges remaining on the secondary transfer conveyance belt 2f. Cleaning blade 16
Removes and adheres to the surface of the secondary transfer / conveying belt 2f for cleaning. When the image forming cycle is started in the color copying machine of the image forming apparatus 0 configured as described above, the photoconductor 1 is driven to rotate counterclockwise in the direction of arrow A shown in the figure by a drive motor (not shown). The end transfer belt 2a is rotated clockwise by a drive roller 2b in the direction of arrow B shown in the figure. With the rotation of the intermediate endless transfer belt 2a, the formation of the black toner image, the formation of the cyan toner image, the formation of the magenta toner image, and the formation of the yellow toner image are performed by the transfer bias by the voltage applied to the primary transfer bias roller 3. The transfer is performed, and a color toner image is finally formed on the intermediate endless transfer belt 2a in the order of black, cyan, magenta, and yellow.

For example, a black toner image is formed as follows. The charging charger of the charging means 8 uniformly charges the surface of the toner image carrying surface 1a to a predetermined potential with a negative charge by corona discharge. Then, the writing optical unit of the exposure unit 10 performs raster exposure using laser light based on the black color image signal. When this raster image is exposed, the toner image carrying surface 1 which is initially uniformly charged
In the exposed portion of the surface a, charges proportional to the amount of exposure light disappear, and a black electrostatic latent image is formed. When the black electrostatic latent image contacts negatively charged black toner on a black developing roller (not shown) of the black developing device 11a, toner adheres to a portion of the toner image carrying surface 1a where the charge remains. Instead, the toner is attracted to a portion having no charge, that is, an exposed portion, and a black toner image similar to the electrostatic latent image is formed. Toner image carrying surface 1a
The black toner image formed thereon is primarily transferred onto the surface of the intermediate endless transfer belt 2a which is driven at a constant speed in contact with the toner image carrying surface 1a. A small amount of untransferred residual toner remaining on the surface of the toner image carrying surface 1a after the primary transfer is used in preparation for reuse of the toner image carrying surface 1a after the primary transfer.
a and the fur brush 9b. On the toner image carrying surface 1a side after the primary transfer, the process proceeds to the cyan image forming process after the black image forming process, and reading of the cyan image data by the color image reading unit 200 starts at a predetermined timing, and the exposure by the cyan image data is performed. A cyan electrostatic latent image is formed on the surface of the toner image carrying surface 1a after the primary transfer by laser light writing of the writing optical unit of the means 10. Then, after the rear end of the previous black electrostatic latent image has passed and before the front end of the cyan electrostatic latent image has arrived, the rotation operation of the revolver developing unit of the developing means 11 is performed, and the cyan developing operation is performed. The machine 11b is set at the developing position, and the cyan electrostatic latent image is developed with cyan toner. Thereafter, the development of the cyan electrostatic latent image area is continued, but when the rear end of the cyan electrostatic latent image has passed, the rotation operation of the revolver developing unit of the developing means 11 is performed as in the case of the black developing machine 11a. Then, the magenta developing device 11c using the next magenta toner is moved to the developing position. This is also completed before the leading end of the next magenta electrostatic latent image reaches the developing position.

In the magenta and yellow image forming processes, the color image reading unit 200 reads the respective read color image data at a predetermined timing, and the operations of forming the electrostatic latent image and developing the above black and cyan images. The description is omitted because it is the same as the process and overlaps. On the intermediate endless transfer belt 2a, black, cyan, magenta, and yellow toner images sequentially formed on the toner image bearing surface 1a are sequentially aligned and transferred to the same surface. Thereby, the intermediate endless transfer belt 2
On a, a toner image in which a maximum of four colors are superimposed is formed. At the time when the image forming operation is started, the transfer target (P) is fed from the transfer paper cassette or the manual feed tray of the paper feeding unit 300 and stands by at the nip of the registration roller pair 13. The leading end of the toner image on the intermediate endless transfer belt 2a reaches the secondary transfer portion (T2) where the nip is formed by the secondary transfer bias roller 4, the secondary entrance side ground roller 6a12, and the secondary exit side ground roller 6b12. At this time, the registration roller pair 13 is driven such that the leading end of the transfer target (P) coincides with the leading end of the toner image, and registration of the transfer target (P) with the toner image is performed. Then, the transfer target (P) is superimposed on the toner image on the intermediate endless transfer belt 2a and passes through the secondary transfer portion (T2). At this time, the four-color superimposed toner image on the intermediate endless transfer belt 2a is transferred by the transfer bias by the voltage applied to the secondary transfer bias roller 4 by the secondary transfer constant current supply means 5b of the constant current supply means 5. It is secondary-transferred collectively on the body (P). And the secondary transfer conveyance belt 2
When passing through a portion facing the above-described charge removing charger 14 disposed downstream of the secondary transfer portion (T2) in the moving direction of the arrow C in the direction of the arrow C in FIG.
The sheet is separated from the secondary transfer conveyance belt 2f and sent to the fixing unit 12. Fixing roller 12 constituting fixing means 12
The toner image is melted and fixed at the nip between the roller a and the pressure roller 12b, sent out of the apparatus body by the discharge roller pair 17, and stacked face up on the paper discharge tray 18 to obtain a full-color copy.

On the other hand, the toner image carrying surface 1a after the primary transfer
Is cleaned by the cleaning blade 9a and the fur brush 9b of the cleaning means 9, and the discharge lamp 19
And the charge is removed uniformly. Further, the toner remaining on the surface of the intermediate endless transfer belt 2a after transferring the toner image to the transfer target (P) is cleaned by the separation / contact mechanism (not shown) against the intermediate endless transfer belt 2a. It is cleaned by the blade 2g. Here, at the time of the repeat copy, the operation of the color image reading unit 200 and the image formation on the toner image carrying surface 1a are performed on the first sheet.
Subsequent to the color yellow image forming process, the process proceeds to the second color black image forming process at a predetermined timing. Further, the intermediate endless transfer belt 2a is transferred to the area where the surface is cleaned by the intermediate transfer body cleaning blade 2g following the batch transfer process of the first four-color superimposed toner image onto the transfer body (P). The first black toner image is transferred first. After that, the operation is the same as that of the first sheet. The above is the copy mode for obtaining a four-color full-color copy. However, in the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. Further, in the case of the single-color copy mode, the developing means 11
Only the developing device of the predetermined color of the revolver developing unit is set in the developing operation state, and the copying operation is performed with the intermediate transfer body cleaning blade 2g kept pressed against the intermediate endless transfer belt 2a. Therefore, an abnormal image due to insufficient transfer due to a change in the inner surface resistance of the intermediate transfer body 2 in which a constant charge is supplied to the primary transfer bias roller or the secondary transfer bias roller 44 of the primary transfer means 3 by the constant current supply means 5. Image forming apparatus 0 on which a high-quality image is formed by preventing the occurrence of image formation can be provided.

FIG. 3 is an explanatory view of the structure of an image forming section according to another embodiment of the present invention. The primary transfer leakage current detecting and supplementing means 7a (inlet primary transfer leakage current detecting means) serving as the leakage current detecting and supplementing means 7 is shown. The supplementary cut 7a1 or the exit primary transfer leakage current detection supplementary cut 7a2) is the primary transfer bias roller 3
A primary entrance-side ground roller 6a11 that grounds both sides of an entrance and exit that enters and exits a transfer bias application unit (T1) that applies a transfer bias to the rotating intermediate endless transfer belt 2a, or
Primary exit side ground roller 6b also used as drive roller 2b
A current value at which a leakage current flows into the sensor 11 is detected, and the detected current value is fed back to the primary transfer constant current supply means 5a to supplement the current. Other configurations and the like are the same as those in FIGS. That is, when a leakage current flows out to the ground roller, information on the leakage current value is set to 1
By supplying the current to the next transfer constant current supply means 5a, the primary transfer constant current supply means 5a replenishes and supplies the current to the primary transfer means 3 by the leakage current, thereby enabling normal transfer.
Therefore, in this embodiment, the driving roller 2b and the primary outlet side ground roller 6b11 are also used.
A constant charge is supplied to the primary transfer means 3 or the secondary transfer means 4 to prevent the occurrence of an abnormal image due to insufficient transfer due to a change in the inner surface resistance of the intermediate transfer body 2 and to form a high quality image. It has become possible to provide a low-cost image forming apparatus.

FIG. 4 is an explanatory view of the structure of an image forming section according to another embodiment of the present invention, in which a secondary transfer leakage current detecting and supplementing means 7b (an entrance secondary transfer leakage current detecting means) serving as a leakage current detecting and supplementing means 7 is provided. The replenishing means 7b1 or the outlet secondary transfer leakage current detecting replenishing means 7b2) is a secondary transfer bias roller 4
Is a driven roller 2c as a grounding means 6 that grounds both sides of an entrance and exit that enters and exits a transfer bias application unit (T2) that applies a transfer bias to the rotating intermediate endless transfer belt 2a.
The current value at which the leakage current flows into the secondary entrance-side ground roller 6a12 also used as the secondary roller 2c1 (the driven roller 2c1) or the secondary exit-side ground roller 6b12 also used as the driven roller 2c (the driven roller 2c2) is detected. Feedback is made to the secondary transfer constant current supply means 5b of the supply means 5 to replenish the divided current. Other configurations and the like are the same as those in FIGS. That is, when a leakage current flows out to the ground roller, the information about the leakage current value is given to the secondary transfer constant current supply means 5b, so that the secondary transfer constant current supply means 5b has a secondary current corresponding to the leakage current. The transfer means 4 is replenished with a current to enable normal transfer. Therefore, since the driven roller 2c1 and the driven roller 2c2 are also used as the secondary entrance-side ground roller 6a12 and the secondary exit-side ground roller 6b12, a constant charge is supplied by the constant current supply unit 5 to the primary transfer unit 3 or the secondary transfer unit. Intermediate transfer body 2 supplied to transfer means 4
Thus, it is possible to provide an inexpensive image forming apparatus 0 in which a high-quality image is formed by preventing occurrence of an abnormal image due to insufficient transfer due to a change in the inner surface resistance value. FIG.
FIG. 9 is a schematic configuration diagram of an image forming unit according to another embodiment of the present invention, in which a secondary transfer leakage current detecting and supplementing unit 7b (an inlet secondary transfer leakage current detecting and supplementing unit 7b1 or an outlet) serving as a leakage current detecting and supplementing unit 7; Secondary transfer leakage current detecting and supplementing means 7b
2) The tension roller of the grounding means 6 in which the secondary transfer bias roller 4 grounds both sides of an entrance and an exit where the secondary transfer bias roller 4 enters and exits a transfer bias applying section (T2) for applying a transfer bias to the rotating intermediate endless transfer belt 2a. The constant current supply means 5 detects a current value at which a leakage current flows into the secondary entrance side ground roller 6a12 also used as the secondary entrance side ground roller 6a12 or the driven roller 2c2 of the driven roller 2c. The current is supplemented by feeding back to the next transfer constant current supply means 5b. Other configurations and the like are the same as those in FIGS. Accordingly, the driven roller 2c2 of the tension roller 2d and the driven roller 2c is
Secondary entrance side ground roller 6a12 and secondary exit side ground roller 6b
Since the constant current supply means 5 supplies a constant charge to the primary transfer means 3 or the secondary transfer means 4, an abnormal image is generated due to insufficient transfer due to a change in the inner surface resistance of the intermediate transfer body 2. This makes it possible to provide a low-cost image forming apparatus 0 in which a high-quality image is formed by preventing image formation.

FIG. 6 is a schematic view showing another example of the configuration of the image forming section of the present invention, in which a primary transfer leakage current detecting and supplementing means 7a (an inlet primary transfer leakage current detecting and supplementing means) serving as a leakage current detecting and supplementing means 7. 7a1 or exit Primary transfer leakage current detecting and supplementing means 7a2) is an entrance / exit for the primary transfer bias roller 3 to enter / exit a transfer bias applying unit (T1) for applying a transfer bias to the rotating intermediate endless transfer belt 2a. The first conductive grounding brush 6a2 (the primary inlet conductive grounding brush 6a21 or the outlet-side outlet grounding member 6b) serving as the outlet-side conductive grounding brush 6b2 serving as the inlet-side grounding member 6a that grounds both sides of the ground. The current value at which the leakage current flows into the secondary outlet side conductive ground brush 6b21 is detected, and the current is fed back to the primary transfer constant current supply means 5a to supply the partial current to the primary transfer bias roller 3. That. The entrance secondary transfer leakage current detection supplementary cut 7b1 or the exit secondary transfer leakage current detection supplementary cut 7b2 is a transfer bias in which the secondary transfer bias roller 4 applies a transfer bias to the rotating intermediate endless transfer belt 2a. The entrance-side conductive ground brush 6a2 of the entrance-side grounding member 6a that grounds both sides of the entrance and exit that enters and exits the application section (T2).
The current value at which leakage current flows into the secondary outlet side conductive grounding brush 6b22 of the outlet side conductive grounding brush 6b2 of the secondary inlet side conductive grounding brush 6a22 or the outlet side grounding member 6b of the outlet side is detected. The current is supplemented by feeding back to the next transfer constant current supply means 5b. FIG. 7 is a configuration diagram of an image forming unit according to another embodiment, and includes primary transfer leakage current detection and supplementing means 7a (inlet 1) as leakage current detection and supplementing means 7.
The secondary transfer leakage current detecting and supplementing means 7a1 or the exit primary transfer leakage current detecting and supplementing means 7a2) is a transfer bias applying unit (where the primary transfer bias roller 3 applies a transfer bias to the rotating intermediate endless transfer belt 2a). T1) an inlet-side grounded sheet metal 6a3 (primary inlet-side grounded sheet metal 6a31) as an inlet-side grounding member 6a for grounding both sides of the entrance and exit.
Alternatively, a primary transfer constant current supply means 5a is detected by detecting a current value at which a leakage current flows into the outlet side grounding metal plate 6b3 (primary outlet side grounding metal plate 6b31) as the outlet side grounding member 6b on the outlet side.
To feed back the current. Secondary transfer leakage current detecting and supplementing means 7b as leakage current detecting and supplementing means 7
(Inlet secondary transfer leakage current detecting and supplementing means 7b1 or outlet 2
The secondary transfer leakage current detecting and supplementing means 7b2) is configured such that the secondary transfer bias roller 4 grounds both sides of the entrance and exit of the secondary transfer bias roller 4 which enters and exits a transfer bias application section (T2) which applies a transfer bias to the rotating intermediate endless transfer belt 2a. The current value at which leakage current flows into the secondary inlet-side ground metal plate 6a32 of the entrance-side ground metal plate 6a3 of the entrance-side grounding member 6a or the secondary outlet-side ground metal plate 6b32 of the outlet-side ground metal plate 6b3 of the outlet-side outlet ground member 6b. Is detected and fed back to the secondary transfer constant current supply means 5b of the constant current supply means 5 to supplement the divided current.

In FIG. 8, the primary transfer leakage current detecting and supplementing means 7a as the leakage current detecting and supplementing means 7 (the inlet primary transfer leakage current detecting and supplementing means 7a1 or the outlet primary transfer leakage current detecting and supplementing means 7a2) is composed of Next transfer bias roller 3
Is an entrance-side conductive ground film 6a4 (1) serving as an entrance-side grounding member 6a that grounds both sides of an entrance and exit that enters and exits a transfer bias application unit (T1) that applies a transfer bias to the rotating intermediate endless transfer belt 2a. By detecting a current value at which a leakage current flows into the primary outlet side conductive ground film 6b41 of the outlet side conductive ground film 6b4 of the next inlet side conductive ground film 6a41 or the outlet side conductive ground film 6b4 of the outlet side,
The current is supplemented by feeding back to the next transfer constant current supply means 5a. The secondary transfer leakage current detecting and supplementing means 7b as the leakage current detecting and supplementing means 7 (the inlet secondary transfer leakage current detecting and supplementing disconnection 7b1 or the outlet secondary transfer leakage current detecting and supplementing disconnection 7b2) includes a secondary transfer bias roller 4. The entrance side conductive ground film 6 of the entrance side grounding member 6a that grounds both sides of the entrance and exit that enters and exits the transfer bias application section (T2) that applies a transfer bias to the rotating intermediate endless transfer belt 2a.
a4 secondary conductive ground film 6a42 or the outlet conductive ground film 6b of the outlet ground member 6b on the outlet side.
4) The current value at which the leakage current flows into the secondary outlet side conductive ground film 6b42 is fed back to the secondary transfer constant current supply means 5b of the constant current supply means 5 to supplement the divided current. The grounding function can be exhibited only when the resistance value of the grounding means 6 is 10 ⁸ Ω or less. The resistance value of the inner surface I (back surface) of the intermediate endless transfer belt 2a measured by a surface resistance measuring device “Hiresta” manufactured by Yuka Denshi Co., Ltd. is 10 ¹⁰ Ω /.
□ Above, no leakage current occurs, so the configuration of the present invention is not required. The above-mentioned area is a surface resistance measurement device “Hirester” manufactured by Yuka Denshi Co., Ltd. for the back resistance value of the intermediate endless transfer belt 2 a when the current is not directly applied to the opposed object as in the indirect application method. Is 10 ¹⁰ Ω
/ □ or less. Intermediate endless transfer belt 2
The lower limit resistance value normally established as a is also 10 ⁷ Ω measured by a surface resistance measurement device “Hirester” manufactured by Yuka Denshi.
/ □. Therefore, in this case, since a leakage current may occur, the application of the present invention is required.

FIG. 9 is a view showing a main configuration of another embodiment of the present invention. A primary transfer bias roller as the primary transfer means 3 or an intermediate endless transfer belt in the secondary transfer bias roller 4 is shown. The distance L1 between the transfer bias applying unit (T) for applying the transfer bias to the transfer bias 2a and the entrance-side grounding member 6a disposed on the entrance side and grounded is located on the exit side from the transfer bias application unit (T). It is shorter than the distance L2 between the outlet side grounding member 6b and the ground. This allows leakage current to flow further to the outlet side, reduces the electric field at the inlet side, and prevents the occurrence of undesired scattering of toner, movement of toner before transfer, undesired pre-transfer, and occurrence of undesired spots and abnormal images. Primary transfer bias roller 3 or 2
A resistance value between a transfer bias applying unit (T) for applying a transfer bias to the intermediate endless transfer belt 2a of the next transfer bias roller 4 and an entrance-side grounding member 6a disposed on the entrance side and grounded (intermediate endless) Transfer belt resistance)
Is higher than the resistance value between the transfer bias applying section (T) and the outlet-side grounding member 6b disposed on the outlet side and grounded. This allows leakage current to flow further to the outlet side, reduces the electric field at the inlet side, and prevents the occurrence of undesired scattering of toner, movement of toner before transfer, undesired pre-transfer, and occurrence of undesired abnormal images.

[0028]

According to the first aspect of the present invention, the toner image bearing surface of the image bearing member which rotates while bearing the toner image to be formed is provided. A primary transfer means for primary-transferring a toner image formed on a toner image bearing surface of the image carrier to an intermediate transfer body which rotates in opposition, and a toner primarily transferred to the intermediate transfer body by the primary transfer means A constant current supplied from a constant current supply unit that supplies a constant current to a secondary transfer unit that secondary-transfers an image onto a transfer target body is transferred to an intermediate transfer body in which the primary transfer unit or the secondary transfer unit rotates. The leakage current flowing into the entrance-side ground member on the entrance side or the exit-side ground member on the exit side of the grounding means for grounding both sides of the entrance and exit to and from the transfer bias application unit for applying the bias is determined by the leakage current detection supplementing means Detect and set the detected current value Since an image is formed by feeding back the current to the current supply unit and supplying an amount of current, a constant charge is supplied to the primary transfer unit or the secondary transfer unit by the constant current supply unit. It has become possible to provide an image forming apparatus in which a high-quality image is formed by preventing the occurrence of insufficient transfer due to a change in the value. Claim 2
According to the invention, the toner formed on the toner image bearing surface of the image carrier on the intermediate transfer member rotating opposite to the toner image bearing surface of the image carrier rotating carrying the toner image to be formed A constant current for supplying a constant current to a primary transfer unit for primary transfer of an image and a secondary transfer unit for secondary transfer of a toner image primarily transferred to an intermediate transfer body by the primary transfer unit to a transfer receiving body. An inlet side of a grounding unit that grounds both sides of an entrance and an exit that enter and exit a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a constant current supplied from a supply unit. The leakage current flowing into the inlet-side grounding member or the outlet-side grounding member of the outlet is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supplying means to supplement the divided current. Intermediate transfer is endless An intermediate endless transfer belt composed of a belt, an intermediate endless transfer belt is stretched, and a driving roller is driven. The driving roller is driven by the intermediate endless transfer belt. Is formed, the occurrence of insufficient transfer due to a change in the inner surface resistance of the intermediate transfer body in which a constant electric charge is supplied to the primary transfer means or the secondary transfer means by the constant current supply means with a simple structure. It has become possible to provide an image forming apparatus in which a high-quality image can be formed while preventing the image formation.

According to the third aspect of the present invention, the toner image of the image carrier is held on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image carrier which holds and rotates the toner image to be formed. A primary transfer unit for primary transfer of the toner image formed on the surface, and a secondary transfer unit for secondary transfer of the toner image primary-transferred to the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A constant current supplied from a constant current supply unit that supplies a current applies a transfer bias to an intermediate transfer member that rotates a primary transfer unit or a secondary transfer unit. The leakage current flowing into the entrance-side grounding member on the entrance side of the grounding means or the exit-side grounding member on the exit side is detected by the leakage current detection supplementing means, and the detected current value is fed back to the constant current supply means. When replenishing minute current An image is formed by using the inlet-side grounding member or the outlet-side grounding member of the grounding means as an inlet-side grounding roller or an outlet-side grounding roller. It has become possible to provide an image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance value of the intermediate transfer member supplied to the transfer means and forming a high-quality image. According to the fourth aspect of the present invention, the toner image is formed on the intermediate image bearing member on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image bearing member which rotates while supporting the toner image to be formed. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill and grounding means Since the entrance-side grounding member or the outlet-side grounding member is also used as a driving roller that stretches and drives the intermediate transfer body, an image is formed. Therefore, a constant charge is supplied to the primary transfer unit or the secondary transfer unit by the constant current supply unit. It is possible to provide a low-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance of the intermediate transfer member supplied to the next transfer unit and forming a high-quality image.

According to the fifth aspect of the present invention, the toner image of the image carrier is held on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image carrier which holds and rotates the toner image to be formed. A primary transfer unit for primary transfer of the toner image formed on the surface, and a secondary transfer unit for secondary transfer of the toner image primary-transferred to the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A constant current supplied from a constant current supply unit that supplies a current applies a transfer bias to an intermediate transfer member that rotates a primary transfer unit or a secondary transfer unit. The leakage current flowing into the entrance-side grounding member on the entrance side of the grounding means or the exit-side grounding member on the exit side is detected by the leakage current detection supplementing means, and the detected current value is fed back to the constant current supply means. When replenishing minute current The image forming is performed by using the entrance-side grounding member or the outlet-side grounding member of the grounding means as a driven roller which stretches the intermediate transfer member and is driven by the intermediate transfer member. It is possible to provide a lower-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance of the intermediate transfer member supplied to the transfer unit or the secondary transfer unit and forming a high-quality image. It became so. According to the sixth aspect of the present invention, the toner image is formed on the intermediate transfer member which rotates while facing the toner image holding surface of the image bearing member which rotates while holding the toner image to be formed. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill and grounding means Since the entrance-side grounding member or the outlet-side grounding member is also used as a tension roller that stretches the intermediate transfer member to urge the tension, an image is formed. Means or 2
It has become possible to provide a lower-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance value of the intermediate transfer member supplied to the next transfer means and forming a high-quality image. . According to the seventh aspect of the present invention, the toner image is formed on the toner image bearing surface of the image carrier on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image carrier which rotates while bearing the toner image to be formed. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the entrance side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill and grounding means Since so as to form an image inlet-side grounding member or an outlet side grounding member as the inlet side conductive ground brush or outlet side conductive ground brush, a primary transfer means constant charge with a constant current supplying means or 2
It has become possible to provide a lower-cost image forming apparatus capable of preventing insufficient transfer due to a change in the inner surface resistance value of the intermediate transfer member supplied to the next transfer means and forming a high-quality image. .

According to the eighth aspect of the present invention, the intermediate transfer member which rotates while facing the toner image bearing surface of the image bearing member which rotates to hold the toner image to be formed carries the toner image of the image bearing member. A primary transfer unit for primary transfer of the toner image formed on the surface, and a secondary transfer unit for secondary transfer of the toner image primary-transferred to the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A constant current supplied from a constant current supply unit that supplies a current applies a transfer bias to an intermediate transfer body where a primary transfer unit or a secondary transfer unit rotates. The leakage current flowing into the entrance-side grounding member on the entrance side of the grounding means or the exit-side grounding member on the exit side is detected by the leakage current detection supplementing means, and the detected current value is fed back to the constant current supply means. When replenishing minute current Since an image is formed by using the entrance-side grounding member or the exit-side grounding member of the grounding means as the entrance-side grounding sheet or the exit-side grounding sheet, a constant charge is supplied by the constant current supply means to the primary transfer means or the secondary transfer means. Thus, it is possible to provide an image forming apparatus which can prevent insufficient transfer due to a change in the inner surface resistance of the intermediate transfer member supplied to the means and can form a high quality image at a lower cost. According to the ninth aspect of the present invention, the toner image is formed on the toner image bearing surface of the image carrier on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image bearing member which rotates to carry the toner image to be formed. A constant current is supplied to a primary transfer unit for primary-transferring the transferred toner image and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. A grounding means for grounding both sides of an entrance and an exit of a transfer bias application unit for applying a transfer bias to an intermediate transfer body in which a primary transfer means or a secondary transfer means rotates with a constant current supplied from a constant current supply means. The leakage current flowing into the entrance-side grounding member on the inlet side or the exit-side grounding member on the exit side is detected by the leakage current detection and supplementing means, and the detected current value is fed back to the constant current supply means to reduce the divided current. Refill and grounding means Since the entrance-side grounding member or the outlet-side grounding member is used to form an image as the entrance-side conductive grounding film or the exit-side conductive grounding film, a constant charge is supplied by the constant current supply unit to the primary transfer unit or the secondary transfer unit. Thus, it is possible to provide an image forming apparatus which can prevent insufficient transfer due to a change in the inner surface resistance of the intermediate transfer member supplied to the means and can form a high quality image at a lower cost.

According to the tenth aspect of the present invention, the toner image of the image carrier is held on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image carrier which holds and rotates the toner image to be formed. Primary transfer of the toner image formed on the surface 1
A constant current supplied from a constant current supply unit for supplying a constant current to a secondary transfer unit and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. An inlet-side grounding member or outlet on the inlet side of the grounding means that grounds both sides of an entrance and an exit that enters and exits a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a current. Current value at which leakage current flows into the outlet-side grounding member on the side is detected by the leakage current detection supplementing means,
The detected current value is fed back to the constant current supply means to replenish the current, and the entrance-side ground member or the exit-side ground member of the grounding means comes into contact with the inner surface side of the intermediate endless transfer belt to form an image. As a result, the image is reliably grounded without adversely affecting the formed image, and a constant charge is supplied by the constant current supply unit to the primary transfer unit or the secondary transfer unit. It has become possible to provide an image forming apparatus that forms a high-quality image while preventing shortage. According to the eleventh aspect of the present invention, the toner image is formed on the intermediate image bearing member on the intermediate transfer member that rotates while facing the toner image bearing surface of the image bearing member that rotates while supporting the toner image to be formed. Primary transfer means for primary-transferring the transferred toner image;
Transfer bias application for applying a transfer bias to an intermediate transfer member on which the primary transfer means or the secondary transfer means rotates with a constant current supplied from the constant current supply means for supplying a constant current to the secondary transfer means for performing the next transfer. The leakage current flowing into the entrance-side entrance-side grounding member or the exit-side exit-side grounding member of the grounding means having a resistance value of 10 ⁸ Ω or less, which grounds both sides of the entrance and exit of the part, is detected by leakage current detection and supplementation means. , And the detected current value is fed back to the constant current supply means to supply an amount of current to form an image, so that the grounding is reliably performed, and a constant electric charge is generated by the constant current supply means. It is possible to provide an image forming apparatus capable of preventing occurrence of insufficient transfer due to a change in the inner surface resistance of the intermediate transfer member supplied to the secondary transfer unit or the secondary transfer unit and forming a high-quality image. Was. According to the twelfth aspect of the present invention, the toner image is formed on the toner image bearing surface of the image carrier on the intermediate transfer member that rotates while facing the toner image bearing surface of the image bearing member that rotates while bearing the toner image to be formed. Transfer means for primary transfer of the transferred toner image, and a surface resistance measuring device "Hirester" manufactured by Yuka Denshi Co., Ltd. of the inner surface resistivity of the inner surface by the primary transfer means.
Constant current for supplying a constant current to the secondary transfer means for secondary-transferring the toner image primary-transferred onto the intermediate transfer body having a measured value of 10 ⁷ Ω / square to 10 ¹⁰ Ω / sq. An inlet side of a grounding unit that grounds both sides of an entrance and an exit that enter and exit a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a constant current supplied from a supply unit. The leakage current flowing into the inlet-side grounding member or the outlet-side grounding member of the outlet is detected by the leakage current detecting and supplementing means, and the detected current value is fed back to the constant current supplying means to supplement the divided current. Since an image is formed, reliable grounding is performed, and a constant charge is supplied by the constant current supply unit to the primary transfer unit or the secondary transfer unit. Of high quality images There is possible to provide an image forming device formed was able to.

According to the thirteenth aspect of the present invention, the toner image of the image carrier is held on the intermediate transfer member which rotates while being opposed to the toner image bearing surface of the image carrier which rotates while carrying the toner image to be formed. Primary transfer of the toner image formed on the surface 1
A constant current supplied from a constant current supply unit for supplying a constant current to a secondary transfer unit and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. An inlet-side grounding member or outlet on the inlet side of the grounding means that grounds both sides of an entrance and an exit that enters and exits a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a current. Current value at which leakage current flows into the outlet-side grounding member on the side is detected by the leakage current detection supplementing means,
The detected current value is fed back to the constant current supply means to replenish the current, and is arranged on the entrance side from the transfer bias application unit for applying the transfer bias to the intermediate transfer body in the primary transfer means or the secondary transfer means and grounded. The distance between the transfer-side bias member and the transfer-side biasing member that applies a transfer bias to the intermediate transfer member in the primary transfer unit or the secondary transfer unit is determined by a distance between the discharge-side grounding member and the ground. The image is formed with a distance shorter than the distance between the two, so that leakage current flows more to the outlet side to reduce the electric field at the inlet side, preventing undesired pre-transfer due to toner movement before transfer, and Insufficient transfer due to a change in the inner surface resistance value of the intermediate transfer member in which a constant charge is supplied to the primary transfer unit or the secondary transfer unit by the current supply unit, undesired toner scattering, and undesired spots It has become able to provide the image forming apparatus to prevent the occurrence of abnormal images such as images high quality image is formed.

According to the fourteenth aspect of the present invention, the toner image of the image carrier is carried on the intermediate transfer body which rotates while facing the toner image carrying surface of the image carrier which carries and rotates the toner image to be formed. Primary transfer of the toner image formed on the surface 1
A constant current supplied from a constant current supply unit for supplying a constant current to a secondary transfer unit and a secondary transfer unit for secondary-transferring the toner image primary-transferred onto the intermediate transfer body by the primary transfer unit to a transfer-receiving body. An inlet-side grounding member or outlet on the inlet side of the grounding means that grounds both sides of an entrance and an exit that enters and exits a transfer bias application unit that applies a transfer bias to an intermediate transfer body in which a primary transfer unit or a secondary transfer unit rotates with a current. Current value at which leakage current flows into the outlet-side grounding member on the side is detected by the leakage current detection supplementing means,
The detected current value is fed back to the constant current supply means to replenish the current, and is arranged on the entrance side from the transfer bias application unit for applying the transfer bias to the intermediate transfer body in the primary transfer means or the secondary transfer means and grounded. The resistance value between the transfer side and the entrance-side grounding means, which is provided at the exit side from the transfer bias applying unit for applying the transfer bias to the intermediate transfer member in the primary transfer means or the secondary transfer means, is grounded. Since the image is formed with a resistance value higher than the resistance value during the transfer, a leak current flows to the outlet side to reduce the electric field at the inlet side, thereby preventing undesired pre-transfer due to the movement of the toner before the transfer. Insufficient transfer, undesired scattering of toner, and unfavorable spots due to a change in the inner surface resistance of the intermediate transfer body in which a constant charge is supplied to the primary transfer unit or the secondary transfer unit by the current supply unit. Prints to prevent the occurrence of abnormal images such as image to provide an image forming apparatus high quality image is formed became possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view illustrating a main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating another main part of the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

0 Image forming apparatus 1 Image carrier, 1a Toner image carrying surface 2 Intermediate transfer member, 2a Intermediate endless transfer belt, 2b
Drive roller, 2c driven roller, 2c1 driven roller,
2c2 driven roller, 2d tension roller, 2e
Cleaning opposite roller, 2f secondary transfer conveyance belt,
2f1 support roller, 2f2 support roller, 2f3 support roller, 2g intermediate transfer member cleaning blade, 2g
h lubricant applying brush, 2i zinc stearate 3 primary transfer means 4 secondary transfer means 5 constant current supply means, 5a primary transfer constant current supply means,
5b Secondary transfer constant current supply means 6 Grounding means, 6a Inlet side grounding member, 6a1 Inlet side grounding roller, 6a11 Primary inlet side grounding roller, 6a12
Secondary inlet side ground roller, 6a2 Inlet side conductive ground brush, 6a21 Primary inlet side conductive ground brush, 6a22 2
Secondary entrance side conductive grounding brush, 6a3 entrance / exit side grounding sheet metal, 6a31 Primary entrance side grounding sheet metal, 6a32 Secondary entrance side grounding sheet metal, 6a4 Entrance side conductive grounding film, 6a41
Primary inlet conductive ground film, 6a42 Secondary inlet conductive ground film, 6b Outlet ground member, 6b1
Outlet-side ground roller, 6b11 Primary outlet-side ground roller, 6
b12 secondary outlet side ground roller, 6b2 outlet side conductive ground brush, 6b21 primary outlet side conductive ground brush, 6b
22 Secondary outlet side conductive grounding brush, 6b3 Exit side grounding sheet metal, 6b31 Primary outlet side grounding sheet metal, 6b32 Secondary outlet side grounding sheet metal, 6b4 Exit side conductive grounding film, 6b
41 Primary outlet side conductive grounding film, 6b42 Secondary outlet side conductive grounding film 7 Leakage current detection supplementary means, 7a Primary transfer leakage current detection supplementary cutoff, 7a1 Entrance primary transfer leakage current detection supplementary cutoff, 7a11 Resistance, 7a2 outlet primary transfer leakage current detection supplementary disconnection, 7a21 resistance, 7b secondary transfer leakage current detection supplementary means, 7b1 entrance secondary transfer leakage current detection supplementary disconnection, 7b11 resistor, 7b2 exit secondary transfer leakage current detection 7b21 resistance 8 charging means 9 cleaning means 9a cleaning blade
9b fur brush 10 exposing means 11 developing means, 11a black developing machine, 11b cyan (Cyan) developing machine, 11c magenta (Magenta) developing machine, 11d yellow (Yellow) developing machine, 11e developing revolver drive section 12 fixing Means, 12a Fixing roller, 12b Pressure roller 13 Registration roller pair 14 Static elimination charger 15 Static elimination charger 16 Cleaning blade 17 Discharge roller pair 18 Discharge tray 19 Static elimination lamp 100 Image forming unit 200 Color image reading unit 300 Feed unit 400 Control unit

Claims (14)

[Claims] An image bearing member that rotates while carrying a toner image; an intermediate transfer member that rotates in opposition to a toner image bearing surface of the image carrier; and a toner image bearing surface that rotates on the intermediate transfer member. A primary transfer unit for primary-transferring the toner image formed on the intermediate transfer body, a secondary transfer unit for secondary-transferring the toner image primarily transferred to the intermediate transfer body to a transfer-receiving body, Constant current supply means for supplying a constant current to the secondary transfer means, and ground means for grounding both sides of a transfer bias applying unit for applying a transfer bias to the intermediate transfer body by the primary transfer means or the secondary transfer means. Detecting the value of the leakage current flowing into the inlet-side grounding member on the inlet side or the outlet-side grounding member on the outlet side as the grounding means, feeding it back to the constant current supply means, and replenishing the leakage current. Means; An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the intermediate transfer body includes an intermediate endless transfer belt formed of an endless belt, and a drive that stretches and rotates the intermediate endless transfer belt. An image forming apparatus, comprising: a roller; and a driven roller that is rotated and driven by stretching the intermediate endless transfer belt together with the driving roller. 3. The image forming apparatus according to claim 1, wherein the entrance-side grounding member or the outlet-side grounding member comprises an entrance-side grounding roller or an outlet-side grounding roller. 4. The image forming apparatus according to claim 1, wherein the entrance-side grounding member or the outlet-side grounding member is also used as a driving roller that stretches and drives the intermediate transfer member. An image forming apparatus comprising: 5. The image forming apparatus according to claim 1, wherein the entrance-side grounding member or the outlet-side grounding member is also used as a driven roller that stretches and follows the intermediate transfer member. An image forming apparatus comprising: 6. The image forming apparatus according to claim 1, wherein the entrance-side grounding member or the outlet-side grounding member stretches an intermediate transfer member to urge the tension. An image forming apparatus, which also serves as a roller. 7. The image forming apparatus according to claim 1, wherein the entrance-side grounding member or the outlet-side grounding member is formed of an entrance-side conductive grounding brush or an outlet-side conductive grounding brush. An image forming apparatus comprising: 8. The image forming apparatus according to claim 1, wherein the entrance-side ground member or the exit-side ground member is formed of an entrance-side ground plate or an exit-side ground plate. An image forming apparatus comprising: 9. The image forming apparatus according to claim 1, wherein the entrance-side ground member or the exit-side ground member is an entrance-side conductive ground film or an exit-side conductive film. An image forming apparatus comprising a conductive ground film. 10. The image forming apparatus according to claim 1, wherein the entrance-side ground member or the outlet-side ground member is on the inner surface side of the intermediate endless transfer belt. An image forming apparatus comprising: an image forming apparatus; 11. The method of claim 1, 2, 3, 4, 5, 6, 7,
10. The image forming apparatus according to claim ⁸ , wherein a resistance value of the grounding means is 10 ⁸ Ω or less. 12. The method of claim 1, 2, 3, 4, 5, 6, 7,
In the image forming apparatus described in 8, 9, or 10, the inner surface resistivity of the inner surface of the intermediate transfer member is 10 ⁷ Ω / □.
An image forming apparatus characterized by having a resistance of from ¹⁰ to 10 ¹⁰ Ω / □. 13. The method of claim 1, 2, 3, 4, 5, 6, 7,
The image forming apparatus according to 8, 9, 10 or 11,
The distance between the transfer bias applying unit and the entrance-side grounding member arranged on the entrance side and grounded is larger than the distance between the transfer bias applying unit and the exit-side grounding member arranged on the exit side and grounded. An image forming apparatus characterized by being set to be short. 14. The method of claim 1, 2, 3, 4, 5, 6, 7,
The image forming apparatus according to any one of 8, 9, 10, 11 and 12, wherein a resistance value between the transfer bias applying unit and an inlet-side grounding unit disposed on the inlet side and grounded is determined from the transfer bias applying unit to the outlet. An image forming apparatus characterized in that the resistance value is set higher than a resistance value between an outlet-side grounding means arranged and grounded on the side.