JPH0358073A - Cleaner for image forming device - Google Patents

Abstract

PURPOSE:To accurately detect an amount of residual toner and to apply a suitable bias voltage by detecting information on an amount of residual toner in plurally divided areas of a photosensitive drum and calculating the minimum bias voltage of each area from the information. CONSTITUTION:A potential sensor SV is composed of (n) potential sensors SV1-SVn, the potential sensors SV1-SVn detect a potential in corresponding areas D1-Dn obtained by dividing the photosensitive drum into (n). The detected signals are inputted to an A/D convertor 27. A CPU 28 detects a copying start signal from a switch 29 to output a sampling pulse to the A/D converter 27; after converting each potential signal into digital data, the CPU 28 fetches it, and calculates a minimum bias value required to remove the residual toner T. The CPU 28 outputs the bias value to a bias control circuit 32 via a D/A converter 31, and applies a voltage of the opposite polarity to the photosensitive drum 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cleaning device for removing residual toner after image transfer in an image forming apparatus such as a copying machine.

[Conventional technology]

Conventionally, in a cleaning device for an image forming apparatus using a cleaning member such as a magnetic brush or a fur brush, the amount of residual toner on the photoreceptor surface after transfer is detected by a photoelectric conversion element, and the minimum amount that can be cleaned is determined according to the detected output. A cleaning device has been proposed that applies a limited bias voltage to the cleaning member (
Special Publication No. 57-176085). This cleaning device actually measures the amount of toner remaining on the photoreceptor surface using a photoelectric conversion element, and determines the bias value from this actual value to avoid applying more bias voltage than necessary to the cleaning member. This prevents deterioration of the photosensitive characteristics of the body drum.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional technology, a photoelectric conversion element is provided between the transfer section and the cleaning section to directly detect the amount of residual toner on the photoreceptor drum. There is a problem in that toner and paper dust scatter and adhere to the light receiving portion of the photoelectric conversion element, making it impossible to accurately detect the amount of remaining toner. Further, since a constant image is not always formed on the entire photosensitive drum, the detected amount of residual toner varies depending on the position where the photoelectric conversion element is installed, and the bias value changes. Therefore, if a bias value calculated from the amount of residual toner detected in a certain area of the photoconductor drum is applied to the entire photoconductor drum, the bias value will be inappropriate in areas other than the toner amount detection area, and the photoconductor The photoreceptor characteristics of the drum may deteriorate. Further, even when the paper size is small, if a bias voltage is applied to the entire photoreceptor drum, areas that do not fit into the paper portion will be adversely affected by the applied bias voltage.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cleaning device for an image forming apparatus that stably detects the amount of residual toner with high accuracy and applies a suitable bias voltage. do.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a cleaning device for an image forming apparatus that removes residual toner from a photoreceptor drum, which is disposed facing a plurality of divided regions in the axial direction of the photoreceptor drum, and is provided in a cleaning device for removing residual toner from a photoreceptor drum. a plurality of detection means each detecting information regarding the amount of residual toner in each of the divided areas; a plurality of cleaning members that remove residual toner in each of the divided areas;
A device comprising a calculation means for calculating a minimum bias value necessary for cleaning each of the divided regions from the output of each of the detection means, and a bias means for applying a predetermined bias voltage to each of the cleaning members from the calculation result. It is. Further, in the cleaning device for the image forming apparatus, the plurality of detection means are potential sensors that detect the potential on the surface of the photoreceptor drum, and the bias voltage applied to each of the cleaning members is controlled by the photoreceptor drum ε. It is polarized.

[Effect]

In the cleaning device according to claim 1 constructed as described above, the photosensitive drum is divided into a plurality of regions in the axial direction, and information regarding the amount of residual toner is detected for each divided region, and information regarding the amount of residual toner is detected from each of the detection results. The minimum bias voltage value necessary for cleaning each divided area is calculated. Then, the bias voltage is applied to each cleaning member corresponding to each divided region.

Further, in the cleaning device for an image forming apparatus according to claim 2, the potential of the surface of the photoreceptor drum on which the electrostatic latent image is formed after exposure is detected for each divided area, and from each detected potential, each of the divided areas The minimum bias voltage value required for cleaning is calculated.

In the cleaning device for an image forming apparatus according to claim 3, a bias voltage having a polarity opposite to that of the photoreceptor drum is applied to each cleaning member to neutralize the electric field of the photoreceptor drum. Facilitates detachment from the drum.

〔Example〕

An overall configuration diagram of a copying machine using the cleaning device of the present invention will be explained with reference to FIG.

In the figure, a contact glass 2 on which a document is placed is provided at the top of a copying machine main body 1, and a document presser 3 is provided above the contact glass 2. Further, an optical system consisting of a document irradiation lamp 4, a reflector 5, mirrors 61, 62, 63, 64, and a lens assembly 7 is configured below the contact glass 2 in the copying machine body 1, and the Light is guided to an exposure area A of a rotatable photosensitive drum 8. Around this photoreceptor drum 8, in the order of its rotational direction, there is a main charging body 9 consisting of a corona discharger, etc., a blank lamp 10, a developing section 11, and a transfer charging section 1.
2, a separation charging section 13, a cleaning section 14, a static elimination lamp 15, etc. are provided.

Here, the blank lamp 10 erases unnecessary charges from the photosensitive drum 8 charged by the main charging section 9, that is, charges other than the area where the electrostatic latent image is formed (hereinafter referred to as the image forming area). It is something. Further, the developing section 11 has a developing roller 111, which supplies toner T onto the photoreceptor drum 8 and develops the electrostatic latent image formed by the exposure into a toner image. . Further, the transfer charging section 12 electrostatically transfers the toner image formed on the photoreceptor drum 8 onto the conveyed transfer paper, and the separation charging section 13 consists of a corona discharger or the like.
This is for electrostatically separating the transfer paper from the photoreceptor drum 8 after transfer. Further, the cleaning section 14 removes residual toner, paper dust, and the like on the surface of the photoreceptor drum 8 after the transferred transfer paper is separated from the photoreceptor drum 8.

As shown in FIG. 1, the cleaning section 14 includes a cleaning blade 141 and a fur brush FB for removing toner T remaining on the photoreceptor drum 8, and a spiral 148 for discharging the removed toner T. ing. The cleaning blade 141 is made of a flexible flat plate made of rubber, sponge, etc., and is attached to a blade attachment plate 143. Furthermore, the blade attachment plate 143 has a weight 145 at one end, and is attached to the other end of a blade support member 144 rotatably attached to a shaft 146 by a blade attachment pin 142.

With this configuration, the blade support member 144 is attached to the weight 1.
45 in a counterclockwise direction around an axis 146;
The rotational force brings the tip of the cleaning blade 141 into pressure contact with the photoreceptor drum 8 at a predetermined pressure. Then, as the photosensitive drum 8 rotates clockwise, the toner T remaining on the surface of the photosensitive drum 8 is scraped off and removed by the cleaning blade 141. Further, below the cleaning blade 141, as shown in FIG. 2, there is provided a fur brush FB consisting of an appropriate number of fur brushes FBI, FB2 to FBn arranged in parallel to the rotation axis of the photoreceptor drum 8. The tip of the brush is arranged so as to rub the surface of the photoreceptor drum 8.

As shown in FIG. 1, each of the fur brushes FBi, FB2 to FBn is arranged in a forward direction relative to the photoreceptor drum 8 (the speed of the tip of the brush is different from the surface speed of the photoreceptor drum 8 (relative speed is provided)). ), and a predetermined bias voltage is applied from the bias control 32 as described later. This noise voltage weakens the electrostatic attraction force of the photoreceptor drum 8 to the residual toner T, and the residual toner T is transferred from the surface of the photoreceptor drum 8 to the fur brush FB.
easily swept away and removed. Note that the toner T adhering to the fur brush FB is scraped off by a screener (147). The residual toner T removed by the cleaning blade 141 and the fur brush FB is discharged from the spiral 148 to a toner collection box (not shown).

Returning to FIG. 3, an exposure area A from the optical system is provided on the photosensitive drum 8 between the main charging section 9 and the blank lamp 10, and further between the exposure area A and the developing section 11. A potential sensor Sv is provided to detect the potential of the photosensitive drum 8 on which an electrostatic latent image has been formed by exposure. The potential sensor Sv is connected to the fur brush FBIF as shown in FIG.
Multiple potential sensors Sv1 corresponding to B2 to FBn
, SV2 to SVn, and are disposed facing the photoreceptor drum 8 and parallel to the rotation axis of the photoreceptor drum 8.

That is, a divided area D obtained by dividing the circumferential surface of the photoreceptor drum 8
The potentials of I, D2 to Dn are detected respectively. Further, at the bottom of the developing section 11, there are 17 pairs of conveyance rollers, several guide plates 16 and 18, and a plurality of loading ports.
A paper feed conveyance mechanism 20 consisting of 19 pairs of rollers is provided, and the paper feed conveyance mechanism 20 feeds the transfer paper through transfer paper force settings 1, 21, 2.
2 to the photosensitive drum 8 side. Separation charging section 13
On the downstream side in the transfer paper conveyance direction, there is a conveyor belt assembly 23,
A fixing section 24, an exit port 25, and a tray 26 are provided, and the transfer paper transferred by the transfer charging section 12 is transferred to the fixing section 24.
After being fixed by a heat roller 241 and a pressure roller 242 in the fixing section 24, the toner is discharged onto a receiving tray 26 through an output port 25.

Next, the operation of the cleaning device according to the present invention will be explained using FIG. 2. As mentioned above, the potential sensor S
v is Svl. It is composed of n sensors Sv2 to svn, each potential sensor SV1. SV2 to Svn are regions D1 and D2 to which the photoreceptor drum 8 is divided into n parts, respectively.
The potential of Dn is detected. Then, the potential sensor Sv+. The detection signals Sv2 to Svn are input to the A/D converter 27 as parallel signals.

When the control circuit 28 consisting of a microcomputer detects the copy start signal from the switch 29, it outputs a predetermined sampling pulse to the A/D converter 27, and converts each potential signal detected by the potential sensors SVISV2 to Svn into El. , E2-En into digital data and import the potential data E1, E2-En to the minimum bias value B1 necessary to remove residual toner T in each divided area DI, D2-Dn, 82- Bn? eL
Calculate. Further, the control circuit 28 receives a drive pulse from the motor 3o for driving the photoreceptor drum 8, and from the drive pulse, the position at which potential detection is started by the potential sensor Sv rotates to a position where it comes into contact with the fur brush FB. Measure the timing of movement. Then, when the potential detection start position rotates to a position where it comes into contact with the fur brush FB, the control circuit 28 changes the bias values Bl, B
2 to sn are sent to the bias control circuit 32 via the D/A converter 31. The bias control circuit 32 applies bias voltages of the bias values B IB2 to Bn to the fur brushes FBjFB2 to FBn, respectively, based on the analog signal D/A converted by the D/A converter 31 to the photosensitive drum 8.
The voltage is applied so that the polarity is opposite to that of the voltage. As a result, the potential of each divided area of the photoreceptor drum 8 is suitably neutralized, and the electrostatic attraction force of each divided area to the residual toner T is weakened, and the residual toner T is transferred to the far plan FB1, FB2 to FBn.
It is easily removed from the surface of the photoreceptor drum 8.

In the above embodiment, information regarding the residual toner T is obtained by detecting the potential of the surface of the photoreceptor drum after exposure, but the present invention is not limited to this. Other detection methods such as direct exposure may also be used. Further, the potential sensor SV1. S
Although the acquisition of detection signals by V2 to sv n and the output of the bias values 81B2 to Bn are performed in parallel, the detection signals and bias data may be output in serial.

〔Effect of the invention〕

As explained above, according to the present invention, the circumferential surface of the photoreceptor drum is divided into a plurality of regions in the axial direction, information regarding the amount of residual toner is detected for each divided region, and each division is Since the minimum bias voltage value necessary for cleaning is calculated for each area and applied to the cleaning member of each divided area, a suitable bias 7 pressure is applied to the entire photoreceptor drum, and the bias voltage value is applied to the entire photoreceptor drum. Stable cleaning performance can be obtained without any negative influence on the photoreceptor drum. In addition, since the potential of the photoreceptor drum on which the electrostatic latent image is formed after exposure is detected and the bias value is calculated from the potential data, residual toner does not scatter and adhere to the sensor. Information regarding the amount of residual toner can be detected accurately and stably, and as a result, accurate bias values can be set.

Furthermore, since the bias voltage is applied with the opposite polarity to that of the photoreceptor drum, residual toner is easily removed from the photoreceptor drum, making cleaning easy.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of a cleaning device for an image forming apparatus according to the present invention, and FIG. FIG. 3 is a diagram showing the overall configuration of an image forming apparatus equipped with a cleaning device according to the present invention. 8... Photosensitive drum, 14... Cleaning device,
27... A/D converter, 28... Control circuit, two
...Switch, 30...Motor, 31...D/A converter, 32...Bias control circuit, s■...Potential sensor FB...Fur brush, T...Toner

Claims (1)

[Scope of Claims] 1. In a cleaning device for an image forming apparatus that removes residual toner from a photoreceptor drum, the cleaning device is disposed facing a plurality of divided regions in the axial direction of the photoreceptor drum and removes residual toner from each divided region. A plurality of detection means each detecting information regarding the amount of toner, a plurality of cleaning members that remove residual toner in each of the divided regions, and a minimum bias value necessary for cleaning each of the divided regions from the output of each of the detection means. 1. A cleaning device for an image forming apparatus, comprising a calculation means for calculating the calculation result, and a bias means for applying a predetermined bias voltage to each of the cleaning members based on the calculation result. 2. The cleaning device for an image forming apparatus according to claim 1, wherein the plurality of detection means are potential sensors that detect the potential on the surface of the photoreceptor drum. 3. The cleaning device for an image forming apparatus according to claim 1 or 2, wherein the bias voltage applied to each of the cleaning members has a polarity opposite to that of the photosensitive drum.