JP6848202B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

The housing is provided with a peripheral surface that abuts on a cylindrical surface above the rotation axis in a cross-sectional view orthogonal to the rotation axis, and is rotationally driven in the same direction as the image carrier at the contact position and adheres to the image carrier. A rotating member that collects the toner, and a tip portion that is arranged in the housing and is above the rotation axis in cross-sectional view and abuts on the cylindrical surface of the image carrier on the upstream side in the rotation direction of the rotating member. A standing wall that is erected between the rotating member and the space above the seat member at a distance from the provided sheet member and the cylindrical surface of the image carrier, and the end of the standing wall that faces the cylindrical surface. , A cleaning device including a vertical wall tip extending toward a cylindrical surface on the downstream side in the rotation direction of the image carrier from the tip of the sheet member is known (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-002344

An object of the present invention is to provide an image forming apparatus capable of suppressing stains on peripheral members of a transfer means due to a non-transfer toner image on an image holder.

In order to solve the above problems, the image forming apparatus according to claim 1 is used.
An image holder that holds a toner image and moves in a circular manner,
A transfer means for transferring the toner image held by the image holder to a recording medium to be conveyed at a transfer position in contact with the image holder.
It is formed on the outer surface of the transfer means and the image holder outside the transfer region of the recording medium in a direction intersecting the transfer direction of the recording medium on the downstream side of the transfer position of the transfer means in the transfer direction of the recording medium. a plate-shaped member than the transfer position so as to close the space projecting to pair toward along the outer surface of the image carrier of the downstream side in the movement direction of the image holding member that, with a,
It is characterized by that.

The invention according to claim 2 is the image forming apparatus according to claim 1.
The plate-shaped member has a facing surface extending in the moving direction of the image holder toward the outer surface of the image holder, and a flow path through which airflow flows is provided between the facing surface and the outer surface of the image holder. Is formed,
It is characterized by that.

The invention according to claim 3 is the image forming apparatus according to claim 2.
The gap between the facing surface and the outer surface of the image holder is 1 mm to 3 mm.
It is characterized by that.

The invention according to claim 4 is the image forming apparatus according to any one of claims 1 to 3.
The moving speed of the outer surface of the image holder is 350 mm / sec or more.
It is characterized by that.

According to the present invention, the periphery of the transfer means due to the non-transfer toner image on the image holder is compared with the configuration having no wall extending toward the outer surface of the image holder outside the transport region of the recording medium. It is possible to suppress the dirt on the member.

It is sectional drawing which shows an example of the schematic structure of the image forming apparatus. It is a perspective view which shows the whole structure of a secondary transfer unit. It is sectional drawing which shows the structure of the transfer apparatus including the paper transport part in an image forming apparatus. It is a plane schematic diagram of the secondary transfer unit including a paper transport area. It is a figure explaining the structure around the secondary transfer part of an image forming apparatus, and the passage of a toner band. (A) is a schematic cross-sectional view showing the flow of air flow around the secondary transfer portion of the image forming apparatus, and (b) is a schematic plan view showing the flow of air flow around the secondary transfer portion and the diffusion of cloud toner. ..

Next, the present invention will be described in more detail with reference to the drawings below with reference to embodiments and specific examples, but the present invention is not limited to these embodiments and specific examples.
In addition, in the explanation using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension is different from the actual one, which is necessary for the explanation for easy understanding. Illustrations other than the members are omitted as appropriate.

(1) Overall configuration and operation of the image forming apparatus (1.1) Overall configuration of the image forming apparatus FIG. 1 is a schematic cross-sectional view showing an example of a schematic configuration of the image forming apparatus 1 according to the present embodiment.
The image forming device 1 is provided at the image forming unit 10, the paper feeding device 20 attached to one end of the image forming unit 10, and the other end of the image forming unit 10, and the printed paper is discharged. It is configured to include a unit 30, an operation information unit 40, and an image processing unit 50 that generates image information from print information transmitted from a higher-level device.

The image forming unit 10 includes a system control device 11, an exposure device 12, a photoconductor unit 13, a developing device 14, a transfer device 15, a paper transport device 16a, 16b, 16c, and a fixing device 17, and is composed of an image processing unit 50. The image data received from is formed as a toner image on the paper P fed from the paper feed device 20.

The paper feed device 20 supplies paper to the image forming unit 10. That is, it is provided with a plurality of paper loading sections for accommodating paper P of different types (for example, material, thickness, paper size, and grain), and the paper P unwound from any one of these plurality of paper loading sections. Is configured to be supplied to the image forming unit 10.

The paper ejection unit 30 ejects the paper P for which the image output is performed by the image forming unit 10. Therefore, the paper ejection unit 30 includes a paper ejection accommodating unit in which the paper P after image output is discharged. The paper ejection unit 30 may have a function of performing post-processing such as cutting and stapling (needle binding) on the paper bundle output from the image forming unit 10.

The operation information unit 40 is used for inputting various settings and instructions and displaying information. That is, it corresponds to a so-called user interface, and specifically, it is configured by combining a liquid crystal display panel, various operation buttons, a touch panel, and the like.

(1.2) Configuration and Operation of Image Forming Unit In the image forming apparatus 1 having such a configuration, the paper loading device 1 designated for each sheet of printing in the printing job among the paper feeding devices 20 according to the timing of image forming. The paper P unwound from the unit is fed to the image forming unit 10.

The photoconductor unit 13 is provided below the exposure device 12 in parallel, and includes a photoconductor drum 131 that is rotationally driven. A charger 132, an exposure device 12, a developing device 14, a primary transfer roller 152, and a cleaning blade 134 are arranged along the rotation direction of the photoconductor drum 131.

The developing apparatus 14 has a developing housing 141 in which a developing agent is housed. A developing roller 142 arranged to face the photoconductor drum 131 is arranged in the developing housing 141, and a layer regulating member (not shown) for regulating the layer thickness of the developing agent is arranged close to the developing roller 142. Has been done.
Each of the developing devices 14 is configured in substantially the same manner except for the developer housed in the developing housing 141, and each forms a yellow (Y), magenta (M), cyan (C), and black (K) toner image. To do. Further, each developing device 14 forms a toner band TB as a strip-shaped toner image in a non-image region located between adjacent toner images on the photoconductor drum 131.

The surface of the rotating photoconductor drum 131 is charged by the charger 132, and an electrostatic latent image is formed by the latent image forming light emitted from the exposure apparatus 12. The electrostatic latent image formed on the photoconductor drum 131 is developed as a toner image by the developing roller 142.

The transfer device 15 includes an intermediate transfer belt 151 as an image holder on which each color toner image formed on the photoconductor drum 131 of each photoconductor unit 13 is multiple-transferred, and each color toner formed on each photoconductor unit 13. The primary transfer roller 152 that sequentially transfers (primary transfer) the images to the intermediate transfer belt 151, and the toner images of each color that are superimposed and transferred on the intermediate transfer belt 151 are collectively transferred (secondary transfer) to the paper that is the recording medium. Cleaning device 155 for removing residual toner, paper dust, etc. adhering to the surfaces of the secondary transfer roller 153 and secondary transfer roller 153, intermediate transfer belt for removing residual toner, paper dust, etc. adhering to the intermediate transfer belt 151. It is configured with a cleaner 158.

Each color toner image formed on the photoconductor drum 131 of each photoconductor unit 13 is a primary transfer unit in which the intermediate transfer belt 151 and each photoconductor drum 131 come into contact with each other, and is predetermined from the power supply device 110 controlled by the system control device 11. The primary transfer roller 152 to which the primary transfer voltage is applied sequentially electrostatically transfers (primary transfer) onto the intermediate transfer belt 151, and a superimposed toner image on which each color toner is superimposed is formed.

The superimposed toner image on the intermediate transfer belt 151 is conveyed to the secondary transfer unit TR in which the secondary transfer roller 153 is pressure-welded to the backup roller 165 via the intermediate transfer belt 151 as the intermediate transfer belt 151 moves. To. When the superimposed toner image is conveyed to the secondary transfer unit TR, the paper P is supplied from the paper feed device 20 to the secondary transfer unit TR at the same timing. Then, a predetermined secondary transfer voltage is applied from the power supply device 110 controlled by the system control device 11 to the backup roller 165 facing the secondary transfer roller 153 via the intermediate transfer belt 151, and the paper P is subjected to a predetermined secondary transfer voltage. The multiple toner images on the intermediate transfer belt 151 are collectively transferred.

The residual toner on the surface of the photoconductor drum 131 is removed by the cleaning blade 134 and collected in a waste toner accommodating portion (not shown), and the surface of the photoconductor drum 131 is recharged by the charger 132.
Further, residual toner, paper dust, etc. on the intermediate transfer belt 151 after the toner image is secondarily transferred are removed and recovered by the intermediate transfer belt cleaner 158, and the surface of the secondary transfer roller 153 is coated with the cleaning device 155. Residual toner, paper dust and the like are removed by the brush 155a and the cleaning blade 155b.

The fixing device 17 has an endless fixing belt 17a that rotates in one direction, a pressure roller 17b that is in contact with the peripheral surface of the fixing belt 17a and rotates in one direction, and pressure contact between the fixing belt 17a and the pressure roller 17b. The nip portion N (fixing region) is formed by the region.
The paper P on which the toner image is transferred in the transfer device 15 is conveyed to the fixing device 17 via the paper conveying device 16a in a state where the toner image is not fixed. The toner image of the paper P conveyed to the fixing device 17 is fixed by the action of crimping and heating by the pair of fixing belts 17a and the pressure roller 17b.

The paper P that has been fixed is fed to the paper ejection unit 30 via the paper transport device 16b.
When the image is output on both sides of the paper P, the front and back sides of the paper P are reversed by the paper transport device 16c and sent to the secondary transfer unit TR in the image forming unit 10 again. Then, after the toner image is transferred and the transferred image is fixed, the toner image is sent to the paper ejection unit 30. The paper P fed to the paper ejection unit 30 is discharged to the paper ejection storage unit after undergoing post-treatment such as cutting and staple (needle binding) as necessary.

(2) Configuration and operation of the transfer device (2.1) Configuration of the transfer device FIG. 2 is a perspective view showing the overall configuration of the secondary transfer unit 154, and FIG. 3 is a transfer device 15 including a paper transfer unit in the image forming device 1. FIG. 4 is a schematic plan view of a secondary transfer unit 154 including a paper transport region.
The transfer device 15 includes a secondary transfer unit 154 including an intermediate transfer belt 151, a primary transfer roller 152, and a secondary transfer roller 153.

The intermediate transfer belt 151, that is contained an appropriate amount of conductive agent such as carbon black in a resin such as polyimide or polyamide is used, is formed so that volume resistivity becomes 10 ⁶ ~10 ¹⁴ Ω · cm The thickness is composed of, for example, a film-like endless belt having a thickness of about 0.1 mm.
The intermediate transfer belt 151 is formed on a drive roller 161 for circulatingly driving the intermediate transfer belt 151, a driven roller 162 for supporting the intermediate transfer belt 151 extending substantially linearly along the arrangement direction of each photoconductor drum 131, and an intermediate transfer belt 151. On the other hand, the tension roller 163 that applies a constant tension and prevents the intermediate transfer belt 151 from meandering, and the support roller 164 and the secondary transfer unit TR that are provided on the upstream side of the secondary transfer unit TR and support the intermediate transfer belt 151. It has a backup roller 165 provided and a cleaning backup roller 166 provided in a cleaning section for scraping residual toner on the intermediate transfer belt 151.

Backup roller 165, a carbon with dispersed EPDM and NBR blend rubber tubing to the surface, the inside is made of EPDM rubber, as its surface resistivity is ¹⁰ 7 ^{~10 10 Ω} / □ roller diameter is 28mm It is formed and the hardness is set to, for example, 70 degrees (Asker C).
The backup roller 165 is arranged on the back surface side of the intermediate transfer belt 151 and forms a counter electrode of the secondary transfer roller 153. A metal feeding roller 165A for applying a bias voltage for forming a secondary transfer electric field at the secondary transfer unit TR is contact-arranged on the backup roller 165.

The primary transfer roller 152 is provided in the primary transfer unit so as to face each photoconductor drum 131 with the intermediate transfer belt 151 interposed therebetween, and a voltage having a polarity opposite to the charging polarity of the toner is applied. As a result, the toner image on each photoconductor drum 131 is sequentially electrostatically attracted to the intermediate transfer belt 151, and the toner image superimposed on the intermediate transfer belt 151 is formed.

The secondary transfer roller 153 as transferring means, the volume resistivity having a surface layer coated with fluorine consists decorated with urethane rubber of the tube is made of a semiconductive rubber of ^{10 6} ~10 10 Ω · cm, the roller diameter It is formed to be 28 mm, and the hardness is set to, for example, 30 degrees (Asker C).
The secondary transfer roller 153 is arranged so as to face the backup roller 165 via the intermediate transfer belt 151, and the toner image held by the intermediate transfer belt 151 together with the backup roller 165 with respect to the paper P conveyed from the paper feed device 20. To form a secondary transfer unit TR for secondary transfer.

A cleaning device 155 that removes residual toner, paper dust, and the like adhering to the surface of the secondary transfer roller 153 is arranged so as to face the secondary transfer roller 153.
The cleaning device 155 includes a coating brush 155a that applies a lubricant 155d to the surface of the secondary transfer roller 153, and a cleaning blade 155b that removes residual toner, paper dust, etc. that have been disturbed in advance by the coating brush 155a. ..
A flicker bar 155c is abutted on the coating brush 155a to remove residual toner, paper dust, etc. adhering to the surface of the coating brush 155a, and at the same time, uniformize the lubricant 155d adhering to the coating brush 155a.

A peeling / reducing device 156 composed of an electrode member 156a and a guide guide 156b is arranged on the downstream side of the secondary transfer unit TR in the paper transport direction, and an outer surface 151a of the intermediate transfer belt 151 is arranged on both outer sides of the guide guide 156b. A wall portion 157 is erected as a plate-shaped member projecting toward.
As shown in FIG. 3, seal members 153a for preventing leakage of waste toner removed by the cleaning blade 155b and collected in the cleaning device 155 are provided at both ends of the secondary transfer roller 153, and the wall portion 157 is provided. Is provided so as to be located outside the paper transport region in the direction intersecting the paper transport direction and inside the seal member 153a.

The wall portion 157 is integrally formed with the guide guide 156b so as to close the space formed by the surface of the secondary transfer roller 153 and the guide guide 156b and the outer surface 151a of the intermediate transfer belt 151 in a cross-sectional view.
One end of the wall portion 157 facing the outer surface 151a of the intermediate transfer belt 151 has an opposing surface 157a extending along the moving direction of the intermediate transfer belt 151.
The facing surface 157a is formed so as to be substantially parallel to the outer surface 151a of the intermediate transfer belt 151 while maintaining a gap G (see FIG. 3) of 1 mm to 3 mm, and a flow path of an air flow generated by the movement of the intermediate transfer belt 151. No (see FIG. 6 (a)).

In the present embodiment, the secondary transfer roller 153, the cleaning device 155, and the peeling / reducing device 156 are arranged interchangeably with respect to the image forming apparatus 1 main body as the secondary transfer unit 154.

The paper P on which the toner image is secondarily transferred is separated and peeled from the intermediate transfer belt 151 while being slowly charged from the back surface of the paper P by the electrode member 156a, and is guided by the guide guide 156b via the paper transport device 16a. Then, it is conveyed to the fixing device 17.

(2.2) Toner band formation and bias application control of the transfer device FIG. 5 is a diagram illustrating the configuration around the secondary transfer unit TR of the image forming apparatus 1 and the passage of the toner band TB, and FIG. 6 (a) is an image formation. A schematic cross-sectional view showing the flow of air flow around the secondary transfer unit TR of the apparatus 1, (b) is a schematic plan view showing the flow of air flow F around the secondary transfer unit TR and the diffusion of cloud toner TN.
As shown in FIG. 5, a power supply device 110 that applies a transfer bias voltage is connected to a power supply roller 165A that applies a transfer bias to the backup roller 165.

The power supply device 110 is a transfer bias power supply 111 that supplies a transfer current for transferring a toner image to the paper P between the secondary transfer roller 153 and the backup roller 165, and a transfer bias power supply 111 formed on the intermediate transfer belt 151, which will be described later. It includes a cleaning bias power supply 112 that supplies a cleaning bias voltage for preventing the transfer of unnecessary toner such as a toner band TB to the secondary transfer roller 153, and a switch 113.

In the image forming apparatus 1 configured as described above, the image forming unit 10 also forms a toner image that is not intended to be transferred to the paper P. Specifically, a toner band TB, which is a strip-shaped toner image, is formed to protect the cleaning blade 134 of the photoconductor drum 131 and discharge the deteriorated toner in the developing apparatus 14.

For example, when low-density images continue continuously, the toner consumption in the developing device 14 is small, so that the toner stays in the developing device 14 for a long time, and the toner is excessively triboelectricly charged and deteriorated. , There was a risk that the graininess of the formed image would deteriorate.
Further, when an image quality adjustment pattern for adjusting the superposition position of the toner images of each color on the intermediate transfer belt 151 is formed, the image quality adjustment pattern has a low image density and the image quality adjustment operation is frequently performed. The toner consumption in the developing device 14 is small, and the toner in the developing device 14 may be excessively triboelectrically charged and deteriorated.

Therefore, in the image forming apparatus 1, a band-shaped toner extending in a direction (width direction) intersecting the rotational movement direction of the photoconductor drum 131 in a non-image region located between adjacent toner images on the photoconductor drum 131. An adjustment operation is performed in which the toner band TB which is an image is formed and the toner retained in the developing apparatus 14 is forcibly consumed.

The toner band TB formed on the photoconductor drum 131 is first transferred onto the intermediate transfer belt 151 at the primary transfer unit, and then a cleaning bias voltage is applied to the backup roller 165 at the secondary transfer unit TR to apply the cleaning bias voltage to the paper P. And it is not transferred to the secondary transfer roller 153, and is finally scraped off and collected by the intermediate transfer belt cleaner 158.
On the other hand, as schematically shown in FIG. 5, the toner in the toner band TB includes a toner charged in a polarity opposite to the original charging polarity of the toner and a toner having a weak charging, and these toners are secondary. It adheres to the transfer roller 153 and is collected in the cleaning device 155.

Due to the demand for high image quality, as the frequency of forming the toner band TB increases, the amount of toner collected in the cleaning device 155 also increases, and in particular, the toner cloud (floating in the air) from the sealing members 153a at both ends of the secondary transfer roller 153. Toner) floats and accumulates in both side regions of the electrode member 156a and the guide guide 156b due to the air flow accompanying the movement of the intermediate transfer belt 151.

In particular, in the central portion where the paper P normally passes in the paper transport region, the floating waste toner adheres to the back surface side of the paper P and is transported together with the paper P, and is unlikely to be accumulated in the electrode member 156a and the guide guide 156b. However, on both sides of the paper transport region, if the paper P is accumulated in the electrode members 156a and the guide guide 156b and the subsequent paper P is a wide paper such as SRA3, there is a possibility that back surface stains may occur on both sides of the paper P. there were.

In the image forming apparatus 1 according to the present embodiment, on both outer surfaces of the guide guide 156b, the outer surface of the intermediate transfer belt 151 is outside the paper transport region in the direction intersecting the paper transport direction and inside the seal member 153a. A wall portion 157 protruding toward 151a is erected.

The wall portion 157 is integrally formed with the guide guide 156b so as to close the space formed by the surface of the secondary transfer roller 153 and the guide guide 156b and the outer surface 151a of the intermediate transfer belt 151 in a cross-sectional view.
Therefore, as schematically shown in FIG. 6B, the cloud toner TN leaking from the sealing member 153a of the secondary transfer roller 153 is blocked by the outer surface 157b of the wall portion 157, and is blocked by the outer surface 157b of the wall portion 157, and is on the upper surface side of the guide guide 156b. Diffusion to is suppressed.

As shown in FIGS. 3 and 6A, one end of the wall portion 157 facing the outer surface 151a of the intermediate transfer belt 151 has an opposing surface 157a extending along the moving direction of the intermediate transfer belt 151, and the facing surface 157a. Is formed so as to be substantially parallel to the outer surface 151a of the intermediate transfer belt 151 while maintaining a gap G of 1 mm to 3 mm.

In the image forming apparatus 1 according to the present embodiment, the process speed Vp is set to 350 mm / sec to 450 mm / sec, and the outer surface 151a of the intermediate transfer belt 151 moves at a moving speed of 350 mm / sec to 450 mm / sec. ..
The gap G formed by the facing surface 157a of the wall portion 157 erected on the guide guide 156b and the outer surface 151a of the intermediate transfer belt 151 becomes a so-called constricted flow path, and is formed by the outer surface 151a of the moving intermediate transfer belt 151. An air flow F is generated toward the downstream side in the moving direction of the intermediate transfer belt 151 (see arrow F in FIG. 6A).

Therefore, as schematically shown in FIG. 6B, the cloud toner TN leaking from the sealing member 153a of the secondary transfer roller 153 is flowed to the downstream side in the moving direction of the intermediate transfer belt 151 by the air flow F. Diffusion to the guide guide 156b side is suppressed. Further, in the gap G in which the narrowed flow path is formed, the air pressure is lower than that in the paper transport region, so that the air flow to the paper transport region, which has a relatively high pressure, does not occur and the cloud toner TN is used. Diffusion is suppressed.
As a result, it is possible to prevent the back surface of the paper from being contaminated by suppressing the accumulation of the cloud toner TN leaked from the sealing members 153a at both ends of the secondary transfer roller 153 in the electrode members 156a and the guide guide 156b in both side regions.

1 ... Image forming device 10 ... Image forming unit 11 ... System control device 110 ... Power supply device 111 ... Transfer bias power supply 112 ... Cleaning bias power supply 113 ... Switching device 120 ...・ Toner band generator 12 ・ ・ ・ Exposure device 13 ・ ・ ・ Photoconductor unit 14 ・ ・ ・ Development device 15 ・ ・ ・ Transfer device 151 ・ ・ ・ Intermediate transfer belt 152 ・ ・ ・ Primary transfer roller 153 ・ ・ ・ Secondary Transfer roller 155 ・ ・ ・ Cleaning device 155a ・ ・ ・ Cleaning brush 155b ・ ・ ・ Cleaning blade 156 ・ ・ ・ Peeling deceleration device 156a ・ ・ ・ Electrode member 156b ・ ・ ・ Guide guide 157 ・ ・ ・ Wall part 157a ・ ・ ・Facing surface 161 ・ ・ ・ Drive roller 162 ・ ・ ・ Support roller 163 ・ ・ ・ Tension roller 164 ・ ・ ・ Support roller 165 ・ ・ ・ Backup roller 166 ・ ・ ・ Cleaning Backup roller 16a, 16b, 16c ・ ・ ・ Paper transfer device 17 ... Fixing device 20 ... Paper feeding device 28 ... Paper guide guide 30 ... Paper ejection unit 40 ... Operation information unit 50 ... Image processing unit

Claims (4)

An image holder that holds a toner image and moves in a circular manner,
A transfer means for transferring the toner image held by the image holder to a recording medium to be conveyed at a transfer position in contact with the image holder.
It is formed on the outer surface of the transfer means and the image holder outside the transfer region of the recording medium in a direction intersecting the transfer direction of the recording medium on the downstream side of the transfer position of the transfer means in the transfer direction of the recording medium. a plate-shaped member than the transfer position so as to close the space projecting to pair toward along the outer surface of the image carrier of the downstream side in the movement direction of the image holding member that, with a,
An image forming apparatus characterized in that. The plate-shaped member has a facing surface extending in the moving direction of the image holder toward the outer surface of the image holder, and a flow path through which airflow flows is provided between the facing surface and the outer surface of the image holder. Is formed,
The image forming apparatus according to claim 1. The gap between the facing surface and the outer surface of the image holder is 1 mm to 3 mm.
The image forming apparatus according to claim 2. The moving speed of the outer surface of the image holder is 350 mm / sec or more.
The image forming apparatus according to any one of claims 1 to 3.

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