JPH04350879A - Transfer device for image forming device - Google Patents

Abstract

PURPOSE:To provide the transfer device for the image forming device where power source can be reduced and the constitution is simplified. CONSTITUTION:In the transfer device 1 of the image forming device a toner image is transferred to a transfer paper on a transfer belt 2 by electrifying the transfer belt 2 and the transfer belt 2 is cleaned by impressing voltage to a fur brush 6. The power source, such as a transformer 9 is provided with a first tap 9a to generate high voltage for electrification of the transfer belt 2, and a second tap 9b to generate low voltage for cleaning. A changeover means, such as a changeover part 8, is provided to changeover between the high voltage and the low voltage and impressing to the fur brush 6, formed with an electrically conductive member. A changeover control means, such as a control part 10, is provided to impress high voltage to the fur brush 6, for at least the size of the transfer paper of the transfer belt 2.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an image forming apparatus that charges a transfer belt to transfer a toner image onto a transfer paper on the transfer belt, and also applies voltage to a fur brush to clean the transfer belt. Regarding a transfer device.

0002

[Prior Art] Conventionally, an image forming apparatus is known in which a transfer sheet is electrostatically attracted to a transfer belt, conveyed to a photoreceptor drum, a toner image on the photoreceptor drum is transferred, and then conveyed to a fixing device and separated. It is being That is, a voltage is applied from the back side of the transfer paper by the transfer charger to charge the transfer belt, thereby transferring the toner image on the photoreceptor drum to the transfer paper.

Further, a fur brush is in contact with the transfer belt, and by applying a voltage to the fur brush after the transfer is completed, residual toner on the transfer belt is drawn to the fur brush and cleaned.

0004

However, in the conventional image forming apparatus, it is necessary to provide a transformer for applying voltage to the transfer charger and a transformer for applying voltage to the fur brush, which increases the cost and requires the use of a transformer. You will need space to place it.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a transfer device for an image forming apparatus that can reduce the power supply and simplify the configuration.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention charges a transfer belt to transfer a toner image onto a transfer paper on the transfer belt, and at the same time applies a voltage to a fur brush. In a transfer device of an image forming apparatus that cleans the transfer belt, a power supply having a first tap that generates a high voltage for charging the transfer belt and a second tap that generates a low voltage for cleaning the transfer belt. a switching means for switching between the high voltage and the low voltage and applying the high voltage to the fur brush formed of a conductive member; and applying the high voltage to the fur brush by at least the size of the transfer paper of the transfer belt. It is equipped with a switching control means.

[0007]

[Operation] According to the transfer device of the image forming apparatus configured as described above,
A high voltage from the first tap is applied to the fur brush to charge the transfer belt by at least the size of the transfer paper;
The transfer belt is charged via the fur brush. Then, the toner image is transferred to the transfer paper by high voltage charging of the transfer belt. Furthermore, residual toner on the transfer belt is attracted to the fur brush and cleaned due to the potential difference between the voltage applied to the fur brush and the voltage on the transfer belt.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a schematic diagram showing an example of an image forming apparatus equipped with a transfer device according to the present invention. The image forming apparatus has a document mounting table 21 and a document presser 22 on its upper surface, and is equipped with an optical system L and an image forming means P inside.

The optical system L includes a light source consisting of a halogen lamp 23 and a reflecting plate 24, reflecting mirrors 25, 26, 27,
It is composed of a lens section 28 and a fixed mirror 29. When the copying operation is started, the light from the light source is reflected by the original placed on the original placing table 21, and the reflected light is guided to the lens section 28 via the reflecting mirrors 25 to 27. Thereafter, the following photosensitive drum 30 is exposed through the fixed mirror 29.

The image forming means P includes a photosensitive drum 30, a main charging device 31, a blank lamp 32, a developing device 33, a transfer device 1, a cleaning section 34, a charge eliminating lamp 341, and the like. After the surface of the photosensitive drum 30 is charged by the main charging device 31, it is exposed to the reflected light to form an electrostatic latent image.

The electrostatic latent image is developed with toner by the developing device 33, transferred to a transfer paper by the transfer device 1, and then separated from the photosensitive drum 30. On the other hand, in order from upstream in the feeding direction, the paper feed port 35, paper feed cassettes 36, 37, paper feed rollers 38, 39, conveyance roller pair 40, conveyance roller pair 4
1 and a pair of registration rollers 42 are provided, whereby the transfer paper is fed to the photosensitive drum 30. Further, after the electric charge remaining on the photoreceptor drum 30 is discharged by the discharge lamp 341, the cleaning section 34 cleans the toner remaining on the surface of the photoreceptor drum 30 after transfer.

A fixing device 43, a discharge roller 44, etc. are disposed downstream in the conveyance direction of the transfer paper after transfer. After the transfer, the transfer paper is fixed by a fixing device 43 and then discharged onto a discharge tray 45 by a discharge roller 44.

Next, the detailed structure of the transfer device 1 will be explained. That is, the transfer device 1 includes a transfer belt 2, a drive roller 3, a driven roller 4, and intermediate rollers 5a, 5.
b, a fur brush 6, a cleaning blade 7, etc. The transfer belt 2 is made of urethane rubber or the like, and is stretched between a driving roller 3 and a driven roller 4 and is attached to the photosensitive drum 3.
The toner image on the transfer sheet 0 is transferred to a transfer paper, and the transfer paper is further electrostatically attracted and conveyed to the fixing device 43. The drive roller 3 is disposed upstream and close to the fixing device 43, and is rotationally driven by a drive motor (not shown) or the like to drive the transfer belt 2. The driven roller 4 is arranged downstream and adjacent to the registration roller pair 42. The intermediate rollers 5a and 5b press the transfer belt 2 against the photosensitive drum 30. Further, the drive roller 3 and the intermediate roller 5a are installed on the ground to discharge the electric charge of the transfer belt 2.

The fur brush 6 is made of a material such as conductive rayon having a predetermined resistance value, and charges the transfer belt 2 with a voltage applied from a switching section 8, which will be described later, and also cleans residual toner on the transfer belt 2. It is something. Note that the cleaning blade 7 is used to clean the fur brush 6.

Next, a configuration showing an example of the electrical system of the fur brush 6 will be explained using FIG. 1. Switching section 8
is the power transformer 9 in response to the switching signal from the control unit 10.
The high voltage from the first tap 9a or the low voltage from the second tap 9b is switched, converted to a DC voltage, and applied to the shaft portion of the fur brush 6. That is, the tap 9a outputs, for example, 2.5 KV AC, and the tap 9b of the transformer 9 outputs, for example, 300 V AC. When a high voltage is applied to the fur brush 6, the transfer belt 2 is charged via the fur brush 6. On the other hand, when a low voltage is applied to the fur brush 6, the charge on the transfer belt 2 is discharged through the fur brush 6, and the residual toner on the transfer belt 2 is removed due to the potential difference between the fur brush 6 and the transfer belt 2. It is designed to be attracted to the fur brush 6.

When copying is started by operating an operation key (not shown), the control section 10 drives the drive roller 3 to drive the transfer belt 2 and outputs a switching signal to the switching section 8 to charge the transfer belt 2. This applies a high voltage to the fur brush 6. The control unit 10 also controls the transfer belt 2.
In order to place the transfer paper on the high-voltage charged portion, the drive of the registration roller pair 42 is controlled to control the conveyance timing of the transfer paper. Furthermore, the control section 10 has a built-in timer, for example, and when the transfer belt 2 is charged with a high voltage corresponding to the size of the transfer paper after the high voltage is applied to the fur brush 6, the switching section is activated when the transfer belt 2 is driven for a predetermined period of time. A switching signal is output to the fur brush 8 to apply a low voltage to the fur brush 6.

Next, the operation of the transfer device 1 having the above structure will be explained. When copying starts, the transfer belt 2 is driven, and a high voltage for performing the transfer is applied to the fur brush 6, and the transfer belt 2 is charged with a high voltage via the fur brush 6. Next, in order to place the transfer paper on the high-voltage charged portion of the transfer belt 2, the registration roller pair 42 is driven so that the leading edge of the charged portion and the leading edge of the transfer paper coincide, and the transfer paper is placed on the transfer belt 2. The photoreceptor drum 30 is electrostatically attracted to the photoreceptor drum 30 and transported toward the pressure contact portion with the photoreceptor drum 30 . Then, the toner image on the photoreceptor drum 30 is transferred to the transfer paper due to the potential difference between the transfer belt 2 and the photoreceptor drum 30.

After the transfer, the transfer paper is conveyed while being attracted to the transfer belt 2, and the charge on the transfer belt 2 is discharged by the intermediate roller 5a and the drive roller 3, and the transfer paper is transferred to the transfer belt 2 at the position of the drive roller 3. The fixing device 43
transported to.

On the other hand, when the transfer belt 2 is charged by the size of the transfer paper, the switching section 8 is switched and a low voltage is applied to the fur brush 6.
The residual toner adhering to the transfer belt 2 is drawn to the fur brush 6 and cleaned by the potential difference between the two.

In this way, a high charging voltage is applied to the fur brush 6 so that the transfer belt 2 is charged by the size of the transfer paper, and the transfer belt 2 is charged via the fur brush 6. , a transformer for directly charging the transfer belt 2 is no longer required. Further, after the transfer belt 2 is charged by the size of the transfer paper, a low voltage for cleaning is applied to the fur brush 6, and residual toner on the transfer belt 2 is cleaned. Note that since the voltage of the transfer belt 2 is always lower than the voltage of the fur brush 6, residual toner adhering to the transfer belt 2 is transferred to the fur brush 6 even during transfer.
It is drawn to and cleaned.

Note that the voltage for cleaning the transfer belt 2 is preferably lower than the high voltage for transfer due to the lifespan of the photoreceptor drum 30, but even if the voltage is higher than the above-mentioned high voltage, the transfer belt 2 may remain. It can attract and clean toner. In other words, the size of the transfer paper of the transfer belt 2 or more,
The transfer belt 2 can also be cleaned by applying a high voltage to the fur brush 3.

[0022]

[Effects of the Invention] Since the present invention charges the transfer belt by applying a high voltage to the fur brush, it is only necessary to have a power source for applying voltage to the fur brush. transformer can be omitted. Therefore, the configuration of the image forming apparatus can be simplified and space can be saved. Furthermore, by applying voltage to the fur brush during the period in which the transfer belt is driven by the size of the transfer paper, the transfer belt can be cleaned even during this period.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an electrical system of a transfer device according to the present invention.

FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus including a transfer device according to the present invention.

[Explanation of symbols]

1 Transfer device 2 Transfer belt 3 Drive roller 4 Driven roller 5a, 5b Intermediate roller 6 Fur brush 7 Cleaning blade 8 Switching section 9 Power transformer 9a 1st tap 9b Second tap 10 Control section 30 Photosensitive drum

Claims (1)

[Claims] 1. A transfer device of an image forming apparatus that charges a transfer belt to transfer a toner image onto a transfer paper on the transfer belt, and also applies voltage to a fur brush to clean the transfer belt. a power source having a first tap that generates a high voltage for charging the belt and a second tap that generates a low voltage for cleaning the belt; and a conductive member that switches between the high voltage and the low voltage. and a switching control means for applying the high voltage to the fur brush by at least the size of the transfer paper of the transfer belt. Transfer device.