JPH03215885A - Cleaning device for image forming device - Google Patents

Abstract

PURPOSE:To offer the cleaning device which displays stable cleaning performance without being affected by temperature and humidity environment by arranging an electrode in contact with tips of brush hairs constituting a brush roller and applying a voltage between this electrode and brush roller so as to heat up the brush hairs. CONSTITUTION:This cleaning device is used for a copying machine and equipped with the brush roller 1 with the conductive brush hairs 11, a recovery roller 2 being in contact with the roller, and the electrode 6 which is arranged in contact with the tips of the brush hairs of the brush roller 1. In warming-up operation, the high voltage V3 for heating the brush hairs is applied to the electrode 6 by feeding electricity to a relay R1 and the brush roller 1 and toner recovery roller 2 are held at the earth potential. The voltage V3 causes a current to flow the brush hairs and Joule's heat is generated to heat up the brush hairs. Consequently, the brush hairs are heated up sufficiently before image forming operation and thus dehumidified, and the desired cleaning performance can be displayed in the image forming operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cleaning device for an image forming apparatus such as a copying machine or a printer.

[Conventional technology]

In electrophotographic image forming apparatuses such as copying machines and printers, an image carrier having a photoconductive photosensitive layer on the surface is used, and image information is exposed onto the surface of the image carrier to form an electrostatic latent image. This latent image is developed by a developing device to form a toner image, and this toner image is transferred to a transfer material and fixed. However, when a toner image is transferred from an image carrier to a transfer material, some toner remains on the image carrier. Therefore, in order to clean this residual toner from the image bearing member in preparation for the next image formation, a cleaning device for cleaning the residual toner is provided.

There are several types of this cleaning device.
Among them, there is a cleaning device using a brush roller.

For example, as shown in FIG. 7, this device applies a bias voltage to a brush roller 1 that rubs an image carrier (in the illustrated example, a photosensitive drum) 5 and a collection roller 2 that is in contact with the roller 1. The residual toner on the photoreceptor 5 is removed onto the brush roller 1, and the toner is collected from the brush roller onto the collection roller 2.

For example, when the residual toner T is charged with positive polarity, the brush bristles 11 constituting the brush roller 1 are charged with negative polarity, and the residual toner from the image carrier 5 is removed by the brush roller 1. As the surface of the image carrier 5 is rubbed, the toner T is scraped off by the brush bristles 11 and is removed by being electrically attracted.

The toner captured by the collection roller 2 is scraped off by the scraper 3, falls into the toner collection conveyance path below the collection roller, and is collected into a toner collection bottle (not shown) by a rotary conveyance means such as a coil or screw provided there. be done.

[Problem to be solved by the invention]

However, in a cleaning device using a brush roller, there is a problem in that the electrical resistance of the brush bristles changes depending on the ambient temperature and humidity, which changes the cleaning performance. As a means of solving such problems,
JP-A-63-249182 discloses the following cleaning device.

That is, a humidity sensor is disposed near the contact area between the brush roller and the image carrier, the sensor detects the ambient humidity, and the bias voltage value applied to the brush roller is switched in accordance with a preset humidity value. This is a cleaning device that allows you to

However, this cleaning device requires a humidity sensor and also requires a control device for switching the bias voltage value applied to the brush roller in accordance with information from the humidity sensor.

Therefore, the present invention eliminates the need for a humidity sensor and a device that controls the voltage applied to the brush roller based on information from the sensor, and has a relatively simple structure that is stable and not easily affected by the temperature and humidity environment. An object of the present invention is to provide a cleaning device that can exhibit cleaning performance.

[Means to solve the problem]

In accordance with the above object, the present invention removes residual toner on the image carrier onto the brush roller by applying a bias voltage to a brush roller that rubs the image carrier and a collection roller that is in contact with the brush roller, respectively. In a cleaning device for an image forming apparatus that collects toner from a brush roller onto the collection roller, an electrode is disposed in contact with the tips of brush bristles constituting the brush roller, and the brush bristles are placed between the electrode and the brush roller. The present invention provides a cleaning device characterized in that it is configured to be able to apply a voltage to generate heat.

The heat generation temperature of the brush bristles may be, for example, a temperature slightly higher than room temperature, for example, 35 to 50°C.

It is desirable that the brush bristles be heated to a desired state in advance during warm-up before the image forming operation starts in the image forming apparatus.Furthermore, in order to heat the brush bristles to the desired temperature state sufficiently efficiently, the brush roller should be heated during cleaning. It is desirable to generate heat while rotating at a rotation speed lower than the rotation speed.

[For production]

According to the cleaning device of the present invention, a high voltage is applied between the brush roller and an electrode placed in contact with the tips of the brush bristles constituting the brush roller to heat the brush bristles, thereby drying the bristles. I can do it.

When voltage is applied to the electrodes during warming up, the brush roller is rotated at a lower rotational speed than during cleaning to sufficiently generate heat and dry the brush roller.

〔Example〕 Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show one embodiment of the present invention.

This cleaning device is used in a copying machine, and includes a brush roller 1 having conductive brush bristles 11, a collection roller 2 in contact with the roller, and a brush roller 1 disposed so as to be in contact with the tip of the brush bristles. An electrode 6 is provided.

The brush roller 1 and collection roller 2 are rotated by a brush roller rotation motor (not shown) via a transmission device (not shown) in the same direction as the rotation direction of the photosensitive drum 5, which is an image carrier. The brush roller 1 is connected to a cleaning power source (voltage Vl) or grounded by a switching relay R1. The collection roller 2 is connected to a cleaning power source (voltage V2) by a relay R1 or grounded.

The electrode 6 is connected to the cleaning power supply (voltage V
4) or connected to the brush bristle heating power supply (voltage V3). This relay R1 is an electromagnetic relay, and when not energized, the contacts are placed on the sides of the cleaning power supplies v1, V2, and (4).

At the time of cleaning, the electromagnetic relay R1 is de-energized, and therefore a high-ass voltage (1) is applied to the brush roller 1 for capturing the residual toner T on the photoreceptor 5 onto the brush bristles 11, and the collection roller A bias voltage (2) for collecting toner from the brush roller 1 is applied to the brush roller 2.

Note that the electrode 6 may normally be in a floating state, but in consideration of preventing toner adhesion, a voltage V4 having the same polarity as the ground or l.toner may be applied. In this example, voltage 4 is applied.

This cleaning device, like the conventional cleaning device shown in FIG. 7, is equipped with a scraper 3 that comes into contact with a collection roller 2, and a toner collection and conveyance path (not shown) that collects the toner scraped off by the scraper.

The values of voltages (1) to (v4) vary depending on the material of the brush bristles used, and further vary depending on the length of the brush bristles, the type of toner, and the type of photoreceptor.

An example of cleaning positively charged toner is as follows.

■ When using RecJR (manufactured by Unitika) for brush bristles V1-+200 (V) V2-Vl-600 (V) V3--800 (V) ■4-Floating toner is positively charged, but ■1 is positively charged. The reason for the voltage is as follows.

In other words, although the brush bristles are conductive, they have a considerably high electrical resistance, and the collection roller 2 to which -400 (V) is applied
The effective voltage V at the tip of the brush bristles becomes 100 (V) in the upper part A of FIG. 1. This voltage (■) can be measured by installing a non-contact electrometer probe near the tip of the brush bristles.

The relationship V=V1+(V2-Vl)/2 is recognized between the bias voltages (1 and V2) and the effective voltage (2) at the tip of the brush bristles.

When using this brush bristles, if the toner is positively charged, each voltage can be in the following range, depending on the length of the bristles and the type of toner, photoreceptor, etc.

Vl--100 ~ +400 (V) 9 ■ V2-V1 = -50 ~ -1000 (V) V3 = -
600 ~ -1000 (V) ■4-0 ~ +300 (
V) or when using SA-7 (manufactured by Toray) for floating brush bristles, V1=-100 (V) Vl-V1=-200 (V) V3=-300 (V) V4-Floating is given as an example. be able to.

Since the brush bristles have a relatively low electrical resistance, the voltage value that can be applied is small. Further, unlike the brush bristles described above, they are not charged by the voltage of the collecting roller.

When using this brush bristles, if the toner is positively charged, each voltage can be in the following range, depending on the length of the bristles and the type of toner, photoreceptor, etc.

V1-0 to -250 (V) Vl-V1--50 to -250 (V) 10 V3--250 to -350 (V) ■4 = 0 to +50 (V) or floating Note that negatively charged toner When used, the polarity is reversed.

Now, after the toner image on the photoreceptor 5 is transferred to the transfer material, the toner T remaining on the photoreceptor 5 (in the illustrated example, positive polarity)
is scraped off by the bristles 11 of the rotating brush roller 1 and is electrically captured by the bristles 11. The toner on the brush roller 1 is collected by a collection roller 2, and the toner on the roller 2 is scraped off from the roller by a scraper 3, falls, and is collected into a collection bottle by a toner collection and conveyance path (not shown).

During this cleaning operation, voltage 4 is applied to the electrode 6 as described above, thereby preventing toner from adhering to the electrode 6.

On the other hand, during warming up, the brush roller 1 is rotated at a lower rotational speed than during cleaning, and the relay R1 is energized to apply a high voltage (3) to the electrode 6 for heating the brush bristles.
is applied, and the brush roller 1 and toner collection roller 2 are brought to the ground potential. Voltage (3) causes current to flow through the brush bristles, generating Joule heat and causing the brush bristles to generate heat.

The heating temperature of the brush bristles is approximately 35°C, which is slightly higher than room temperature.
The temperature should be ~50'C. By operating in this manner, the brush bristles can be sufficiently heated and dehumidified before the image forming operation, and the desired cleaning performance can be more reliably exhibited during the image forming operation.

FIG. 2 shows that when warming up the image forming apparatus, a high voltage is applied to the electrode 6 while rotating the brush roller 1 at a lower rotational speed than during cleaning, and after warming up, the brush roller 1 is rotated at a rotational speed that is sufficient for predetermined cleaning. A control means for switching and stopping the application of voltage 3 to the electrode 6 is schematically shown.

FIG. 3 shows the operation timing of each part of the cleaning device and the parts related thereto.

According to this control means, the brush roller rotation motor is connected to the brush roller 1 via the brush roller rotation switching clutch and (low speed l1 rotation gear or high speed rotation gear).
is connected to.

The brush roller rotation switching clutch is an electric clutch,
When not energized, it is in the high-speed rotating gear, and when energized it switches to the low-speed rotating gear.

In addition, the cleaning power supplies (Vl, V2, V4) and the brush bristle heating power supply (■3) are connected to the brush roller 1, toner collection roller 2 (omitted in Fig. 2), and electrode 6 via the power switching relay R1. has been done.

As described above, the power supply switching relay R1 has a contact on the cleaning power source side when not energized, and switches to the brush bristle heating power source side when energized.

Further, when the temperature control circuit of the fixing device and the fixing device for melting and fixing the toner image on the transfer material reach a temperature TF or more necessary for fixing the toner image, warming up ends and copying becomes possible. A copy-enabled indicator lamp is provided to indicate that the copy is possible.

As can be seen from FIGS. 2 and 3, when the main body power supply 13 is turned on, the main body power is turned on, and power is supplied to the brush roller rotation motor via a control circuit (not shown), and the brush roller rotation switching clutch and power supply switching are also performed. power supply relay, brush bristle heating power supply, and fuser temperature control circuit.

As a result, the brush roller rotation switching clutch enters the low speed rotation gear side, and the brush roller 1 and collection roller 2 begin to rotate at a lower speed than during cleaning. In addition, the contact point of the power supply switching relay is on the side of the power supply for heating the brush hair, and
A voltage V3 is applied to. Meanwhile, the fuser temperature control circuit also begins to operate.

Thus, the brush bristles 11 of the brush roller 1 generate heat and dry prior to the image forming operation. At this time, since the brush roller rotates at a low speed, effects such as abrasion of the photoreceptor and generation of frictional heat can be ignored. Note that the photoreceptors may be rotated at the same time for the purpose of dehumidifying the surface of the photoreceptor.

When the temperature of the fixing device reaches or exceeds TF, warming up ends, and at the same time, the copy ready indicator lamp lights up.

At the same time, the brush roller rotation motor 14 is stopped, the brush roller rotation switching clutch is switched to the high speed rotation gear side, the brush bristle heating power source (3) is turned off, the power source switching relay R1 is turned off, and its contacts are This is the power supply side for cleaning.

When the copy start switch is turned on after the copy ready indicator lamp lights up, the brush roller rotation motor starts rotating again, and at the same time the brush roller 1 rotates at the number of rotations required for cleaning, the cleaning power is turned on, and the brush roller 1 and A voltage V1 is applied to the collection roller 2 and the electrode 6,
■2 and ■4 are applied. The copy ready indicator lamp goes out at the same time as the copy start switch is turned on.

Further, in the embodiment described above, the electrode 6 is used as the bristle heating power source, but the image carrier 5 or the collecting roller 2 itself may be used as the bristle heating electrode. The fourth example is
This will be explained with reference to FIGS.

In the apparatus shown in FIG. 4, the image carrier 5 also serves as a brush bristle heating electrode. When brush bristles are heated, high voltage is applied to brush roller 1.
3 is applied, and the toner collection roller 1 5 2 is floated. Note that (1) and (2) are cleaning power supplies, and R2 is a power supply switching relay.

In the apparatus shown in FIG. 5, the image carrier 5 and the toner collection roller 2
also serves as an electrode. When heating brush bristles, brush roller 1
A high voltage (3) is applied to the toner collecting roller 2, and the toner collecting roller 2 is grounded. In addition, V1, ■2 are cleaning power supplies, R3
For example, it is a power supply switching relay.

In the apparatus shown in FIG. 6, the toner collection roller 2 also serves as an electrode. When the brush bristles are heated, high voltage is applied to the toner collection roller 2.
3 is applied. Note that V1 and (2) are cleaning power supplies, and R4 is a power supply switching relay.

Other aspects of these devices are constructed similarly to the cleaning device shown in FIG.

〔Effect of the invention〕

According to the present invention, there is no need for a humidity sensor or a device for controlling the voltage applied to the brush roller based on information from the sensor, and the structure is relatively simple and is not easily affected by the temperature and humidity environment. A cleaning device that can exhibit stable cleaning performance can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a schematic block diagram of a control means for generating heat in the brush bristles in advance during warm-up of the image forming apparatus, and FIG.
4 to 6 are schematic diagrams showing other embodiments of the present invention, and FIG. 7 is an explanatory diagram of a conventional example. 1... Brush roller 11... Brush bristles 2... Collection roller 5... Photoreceptor 6... Electrode Applicant Minolta Camera Co., Ltd. 1 7 Fig. 4 Fig. 6 Fig. 5

Claims (2)

[Claims] (1) A bias voltage is applied to each of the brush roller that rubs the image carrier and the recovery roller that is in contact with the brush roller to remove the residual toner on the image carrier onto the brush roller, and remove the toner from the brush roller. In a cleaning device for an image forming apparatus, an electrode is disposed in contact with a tip of a brush bristle constituting the brush roller, and the brush bristle generates heat between the electrode and the brush roller. A cleaning device characterized in that it is configured to be able to apply a voltage. (2) When warming up the image forming apparatus, the brush roller is rotated at a lower rotation speed than during cleaning, and a voltage is applied between the electrode and the brush roller to generate heat in the brush bristles. cleaning equipment.