JPH11296037A - Cleaning means and image forming apparatus - Google Patents

Abstract

(57) [Object] To provide a cleaning means and an image forming apparatus which can prevent toner leakage due to chipping of a cleaning blade. The cleaning device includes a cleaning blade for scraping off residual toner on a photosensitive drum (image carrier) and a squeeze sheet for guiding the scraped residual toner to a cleaning container. The sheets 53 and 54 that partially contact in the longitudinal direction of the sheet are provided at an exposed portion between the portion where the cleaning blade 51 contacts the photosensitive drum 1 and the portion where the squeeze sheet 55 contacts the photosensitive drum 1.
According to the present invention, it is possible to reduce the amount of the residual toner once collected in the cleaning container 52 to adhere to the surface of the photosensitive drum 1 in the exposed portion, and even if the edge of the cleaning blade 51 is chipped, the residual toner is removed. Leakage can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus employing an electrophotographic system and a cleaning means used in the image forming apparatus.

[0002]

2. Description of the Related Art FIG. 6 shows an example of an image forming apparatus adopting an electrophotographic system using a contact charging device.

FIG. 6 is a cross-sectional view of a main part of a conventional image forming apparatus. In FIG. 6, reference numeral 1 denotes a photosensitive drum serving as an image carrier.
A contact portion (nip portion) n is formed between the charging roller 2 and the photosensitive drum 1 on the outer surface thereof.

After the photosensitive drum 1 is charged by applying a bias voltage from a power supply 19 to the charging roller 2, the photosensitive drum 1 is exposed to light 14 by performing an exposure 14 on the photosensitive drum 1. A latent image is formed. The electrostatic latent image on the photosensitive drum 1 is developed by a developing device 15 to be visualized as a toner image, and the toner image is transferred to a transfer paper 16 as a transfer material by a transfer roller 17. The transfer material 16 onto which the toner image has been transferred is conveyed to a fixing device (not shown), and is heated by the fixing device to receive the toner image. The toner remaining on the photosensitive drum 1 after the transfer of the toner image to the transfer paper 16 is removed by the cleaning device 18, and the photosensitive drum 1 whose outer surface has been cleaned is again used for image formation.

In recent years, the performance required for an image forming apparatus such as a laser beam printer has been remarkably improved, and in particular, it is essential that a process cartridge has a higher speed, a higher durability, and a longer life due to the higher speed. At the same time, an increase in resolution and a reproducibility of high resolution of about 2400 dpi are also required.

As an example of prolonging the life, if printing is performed at an A4 size and a printing rate of 4%, a process cartridge having a life of 15,000 sheets is printed at a low printing rate of 2%.
As many as 00 sheets can be passed. Since high-speed, high-durability, and long-life image forming apparatuses are used in various ways in the market, the number of sheets passed through the process cartridge varies greatly. For this reason, particularly when the toner is used at a low printing rate, the photosensitive drum reaches the end of its life and fog may occur even though the toner has not run out.

Immediately before the end of the life of the photosensitive drum,
Since a print job or copying of 00 sheets was performed, the photosensitive drum reached its end of life during printing, and an extremely large amount of toner was sometimes scattered on the main body.

On the other hand, the image forming apparatus is required to further reduce the printing cost. As described above, the photosensitive drum, which is an image carrier used in a high-speed, high-durability, and long-life image forming apparatus, is required to have a very long life.

In order to extend the life of the photosensitive drum, there are methods such as hardening the photosensitive layer, increasing the film thickness, and reducing the number of idle rotations of the photosensitive drum. Is the direction of image quality degradation.

Therefore, as a method of hardening the surface layer of the photosensitive layer, there is a method of dispersing fluororesin particles to increase the slipperiness of the surface layer. However, this method also tends to scatter the exposure and degrade the image quality. As a method of hardening the photosensitive layer without deteriorating the image quality, there is a method of forming the surface layer of a high molecular weight resin.
Conventionally, a commonly used ordinary resin is a polycarbonate resin having a molecular weight of about 20,000, but recently a high molecular weight resin having a molecular weight of 40,000 or more can be constituted by polycarbonate, polyarylate, or the like.

Various cleaning means have been conventionally proposed for removing residual toner on the photosensitive drum as an image carrier. However, a cleaning blade made of an elastic member such as rubber is used to attach the edge of the photosensitive drum. Is widely used because it has a simple configuration and can be realized at low cost, and has a superior toner removing function.

[0012]

However, when the above-mentioned highly durable photosensitive drum is used, there are the following problems.

That is, in a high-temperature and high-humidity environment (for example, at a temperature of 30
(80 ° C., 80% humidity) or a decrease in the elasticity of the cleaning blade due to an increase in the temperature of the image forming apparatus due to continuous printing, and an increase in the friction coefficient of the surface of the photosensitive drum. It may be lost. In particular, in the case of the contact AC charging system, the friction on the photosensitive drum surface becomes large in the charging area in the longitudinal direction, and the fogged toner and transfer residual toner do not reach the cleaning blade outside the developing area. In some cases, the cleaning blade was turned up.

Conventionally, in order to solve the above problem, a slipperiness is improved by mixing particles of a fluororesin in the charge transfer layer, or a low molecular weight resin having a molecular weight of about 20,000, which is very easy to scrape, is thickened. However, it is difficult to achieve both long life and high image quality by using these methods. Another method is to increase the elasticity of the cleaning blade in a high-temperature environment by selecting a cross-sectional shape and material properties to prevent the cleaning blade from being turned up.

However, even if the above measures are taken,
Since the friction inside the charged area was large, the friction caused the friction to cause the phenomenon that the edge of the cleaning blade was chipped. Then, the toner collected in the cleaning container leaks from the place where the cleaning blade is chipped, and the leaked toner adheres to the photosensitive drum to disturb the latent image, or the leaked toner floats in the image forming apparatus. Problems such as soiling of the device occur.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a cleaning unit and an image forming apparatus capable of preventing toner leakage due to chipping of an edge of a cleaning blade.

[0017]

According to a first aspect of the present invention, there is provided a cleaning blade for scraping off residual toner on an image carrier, and guiding the scraped residual toner to a cleaning container. In a cleaning unit including a squeeze sheet, a sheet that partially abuts in the longitudinal direction of the image carrier is sandwiched between a portion where the cleaning blade and the image carrier abut and a portion where the squeeze sheet and the image carrier abut. Characterized in that it is provided on the exposed portion.

According to a second aspect of the present invention, there is provided a cleaning means comprising a cleaning blade for scraping off residual toner on the image carrier and a squeeze sheet for guiding the scraped residual toner to a cleaning container. A sponge member partially abutting in the longitudinal direction is provided on an exposed portion sandwiched between a portion where the cleaning blade contacts the image carrier and a portion where the squeeze sheet contacts the image carrier.

According to a third aspect of the present invention, there is provided a cleaning means comprising a cleaning blade for scraping off residual toner on the image carrier and a squeeze sheet for guiding the scraped residual toner to a cleaning container. A magnetic member which is partially adjacent in the longitudinal direction of the cleaning blade is provided at an exposed portion sandwiched between a portion where the cleaning blade contacts the image carrier and a portion where the squeeze sheet contacts the image carrier. Item 4 is an image carrier, charging means for charging the image carrier to a predetermined potential, and exposure means for forming an electrostatic latent image on the image carrier by exposing the image carrier. Developing means for developing the electrostatic latent image using toner to form a toner image;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the image carrier to a transfer material; a cleaning unit that cleans residual toner on the image carrier; and a fixing unit that fixes a toner image on the transfer material. The cleaning means is constituted by the cleaning means according to claim 1 or 2.

According to a fifth aspect of the present invention, there is provided an image carrier, charging means for charging the image carrier to a predetermined potential, and forming an electrostatic latent image on the image carrier by exposing the image carrier. Exposure means for developing the electrostatic latent image using toner to form a toner image; transfer means for transferring the toner image from an image carrier to a transfer material; 3. An image forming apparatus comprising: a cleaning unit for cleaning a toner; and a fixing unit for fixing a toner image on a transfer material, wherein the toner is made of a magnetic toner including a magnetic material, and the cleaning unit is the cleaning unit. Alternatively, the cleaning means is constituted by the cleaning means described in 3.

Therefore, according to the present invention, the cleaning blade and the image carrier are provided with a sheet or sponge member which partially abuts in the longitudinal direction of the image carrier or a magnetic member which is partially close in the longitudinal direction of the image carrier. Is provided at an exposed portion sandwiched between a contact portion of the cleaning sheet and a portion of the squeeze sheet and the image carrier, thereby reducing the amount of residual toner once collected by the cleaning means to adhere to the surface of the image carrier at the exposed portion. Therefore, even if the edge of the cleaning blade is chipped, leakage of the residual toner from the cleaning unit can be prevented.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 1 is a longitudinal sectional view of a main part of an image forming apparatus according to the present invention. The image forming apparatus has a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image carrier. The photosensitive drum 1 is driven to rotate at a peripheral speed of 110 mm / sec in a direction indicated by an arrow in the figure.

A charging roller 2 as a contact charging member is in contact with the surface of the photosensitive drum 1, and the charging roller 2 is formed by coating a core metal with a roll base. The roll base is formed of a conductive rubber layer in which carbon is dispersed in rubber such as EPDM, and an oscillating voltage bias in which a DC voltage and an AC voltage are superimposed by a bias power supply 6 is applied to a cored bar.

The charging roller 2 is in contact with the surface of the photosensitive drum 1 and rotates following the rotation of the photosensitive drum 1 in the direction indicated by the arrow. The charging roller 2 uniformly charges the surface of the photosensitive drum 1 to a predetermined potential of about -700 V by the driven rotation and the application of the bias voltage.

The photosensitive drum 1 uniformly charged by the charging roller 2 forms an electrostatic latent image on its surface by light irradiation from the exposure device 3. Note that the exposure device 3
It has an optical system unit that scans light emitted from a light source such as a semiconductor laser with a known polygon mirror or the like, and reflects the laser light from the mirror with a turn-back mirror.
4 irradiates the photosensitive drum 1.

The electrostatic latent image formed on the photosensitive drum 1 is
The developing device 4 develops the toner image by attaching the negatively frictionally charged toner to the toner. Then, the toner image on the photosensitive drum 1 is transferred onto the transfer material 11 supplied to the transfer unit in synchronization with the toner image.
That is, a transfer roller (transfer device) 10 is provided on the back surface of the transfer material 11.
As a result, the toner image on the photosensitive drum 1 is transferred to the surface of the transfer material 11. Then, the transfer material 11 carrying the unfixed toner image on the surface by the transfer is sent to a fixing unit (not shown), where the toner image is fixed, and then discharged outside the apparatus main body.

The residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed by the cleaning blade 51 of the cleaning device 5 and collected in the cleaning container 52. Provided for image formation.

In the above-described image forming process, the photosensitive layer of the photosensitive drum 1 includes the charging roller 2, the transfer roller 10,
It is rubbed by the transfer material 11, the cleaning blade 51, and the like, and gradually wears with long-term use.

Here, the cleaning device 5 will be described with reference to FIG. FIG. 2 is a perspective view of the cleaning device 5.

In the cleaning device 5 shown in FIG. 2, a region L indicates a region charged by the charging roller 2, and a region L2 indicates a developing region of the developing device 4. Normally, the charged area L is set wider than the developing area L2, so that L <L2, and the areas L1 and L3 are
And the area outside the development area L2. Also, 53
And 54 are sheets having a thickness of about 0.2 to 0.5 mm,
These are arranged so as to cover the regions L1 and L3, respectively.

Next, based on FIG.
4 will be described.

In the present embodiment, the sheets 53, 5
4 is disposed such that an edge is located at an opening between the cleaning blade 51 and the squeeze sheet 55, and an exposed portion S of the cleaning device 5 on the surface of the photosensitive drum 1 from the inside of the cleaning container 52 is suppressed to be small. I do. In the present embodiment, the width of the exposed portion S is set to about 0.
It was 5 to 1.0 mm.

Here, the result of confirming the cleaning effect of the image forming apparatus according to the present embodiment will be described.

The evaluation was carried out by setting the image forming apparatus in a thermo-hygrostat controlled at a temperature of 30 ° C. and a humidity of 80%, and using a double-sided mechanism (not shown) using letter-size (11 × 8.5 inch) plain paper. This was done by printing 40000 pages on both sides. The printed image pattern has a printing ratio of about 1%
It was made to become. When double-sided printing is performed, the transfer material 11 that has passed through a fixing device (not shown) passes through the transfer portion again, so that the temperature around the photosensitive drum 1 particularly rises, and in this evaluation, the temperature may exceed 50 ° C. Was.

However, although the cleaning blade was chipped at the end, the leakage of the toner was extremely small until the end, and good cleaning performance was maintained. Therefore, high image quality could be maintained without causing contamination of the main body due to toner leakage and accompanying deterioration of image quality.

Further, the life of the photosensitive drum was evaluated in all environments of low temperature, normal temperature and high temperature. The charge transfer layer on the surface of the photosensitive drum 1 was formed with a thickness of 25 μm. The evaluation was performed by intermittent printing in which the image forming apparatus was stopped every time two single-sided prints were printed on letter-size plain paper. As a result, even after printing over 30,000 pages in all environments, image defects such as charging failure and cleaning failure do not occur. Was realized. In this evaluation, there was no edge chipping in the areas L1 and L3 of the cleaning blade 51 shown in FIG.

In this embodiment, the thickness of the charge transfer layer of the photosensitive layer of the photosensitive drum 1 is reduced to about 25 μm, and the photosensitive layer in which the particles of the fluororesin are not dispersed is used.
Gray scale reproducibility by isolated dot, PWM control, etc., reproducibility of image edges, etc. have been greatly improved.
It was confirmed that high image quality was also satisfied.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view of the photosensitive drum and the cleaning device of the image forming apparatus according to the present embodiment.

In this embodiment, the members 53 ′ and 54 ′ are formed by the sheets 53 a ′ and 54 a ′ and the sponge 53.
b 'and 54b' constitute members 53 'and 54', respectively, and these members 53 'and 54' are respectively arranged in regions L1 and L3 shown in FIG. Also, the exposed portion S
Is about 0.5 to 1.0 mm as in the first embodiment.

In the present embodiment, the opening S is narrowed to reduce the exposed portion S, and the sponges 53b 'and 54b'
Is brought into contact with the photosensitive drum 1 so that the photosensitive drum 1
Is improved in cleaning performance. Also in this embodiment, it was confirmed that the same effects as those of Embodiment 1 could be obtained, and high image quality could be satisfied.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a sectional view of the photosensitive drum and the cleaning device of the image forming apparatus according to the present embodiment.

The present embodiment is effective for an image forming apparatus using a toner containing a magnetic material. That is, in the present embodiment, the sheets 53a ", 54a"
b "and 54b" constituted members 53 "and 54", respectively, which were arranged in regions L1 and L3 shown in FIG. The width of the exposed portion S is set to 0.5 as in the first embodiment.
It was about 1.0 mm.

In the present embodiment, the opening is narrowed to reduce the exposed portion S, and the magnetic members 53b "and 54b"
In the vicinity of the region L1 and the region L3 to prevent the toner collected in the cleaning container 52 from attracting the magnetic toner flowing backward to the magnetic members 53b ″ and 54b ″ to return to the photosensitive drum 1. The cleaning property can be improved. And also in the present embodiment, the same effect as in the first embodiment can be obtained,
It was confirmed that high image quality was also satisfactory.

[0045]

As is apparent from the above description, according to the present invention, a sheet or a sponge member partially abutting in the longitudinal direction of the image carrier or partially approaching in the longitudinal direction of the image carrier. Since the magnetic member is provided in an exposed portion between the portion where the cleaning blade and the image carrier abut and the portion where the squeeze sheet and the image carrier abut, the residual toner once collected by the cleaning means is exposed in the image carrier. The amount of redeposition on the surface can be reduced, and even if the cleaning blade has chipped edges,
The effect is obtained that leakage of the residual toner from the cleaning means can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an image forming apparatus according to the present invention.

FIG. 2 is a perspective view of the cleaning device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a photosensitive drum and a cleaning device of the image forming apparatus according to Embodiment 1 of the present invention;

FIG. 4 is a sectional view of a photosensitive drum and a cleaning device of an image forming apparatus according to Embodiment 2 of the present invention;

FIG. 5 is a sectional view of a photosensitive drum and a cleaning device of an image forming apparatus according to Embodiment 3 of the present invention;

FIG. 6 is a longitudinal sectional view of a main part of a conventional image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image carrier) 2 Charging roller (charging means) 3 Exposure device (exposure means) 4 Developing device (developing means) 5 Cleaning device (cleaning means) 10 Transfer roller (transfer means) 11 Transfer material 51 Cleaning blade 52 Cleaning container 53, 54 Sheet 53a ', 54a' Sheet 53b ', 54b' Sponge (sponge member) 53a ", 54a" Sheet 53b ", 54b" Magnetic member 55 Squeeze sheet S Exposed portion

Claims (5)

[Claims] 1. A cleaning device comprising: a cleaning blade for scraping off residual toner on an image carrier; and a squeeze sheet for guiding the scraped residual toner to a cleaning container; Cleaning means provided on an exposed portion sandwiched between a portion where the cleaning blade contacts the image carrier and a portion where the squeeze sheet contacts the image carrier. 2. A cleaning device comprising: a cleaning blade for scraping residual toner on an image carrier; and a squeeze sheet for guiding the scraped residual toner to a cleaning container; A sponge member contacting the cleaning blade and an image carrier at an exposed portion sandwiched between a portion at which the cleaning blade contacts the image carrier and a portion at which the squeeze sheet contacts the image carrier. 3. A cleaning device comprising: a cleaning blade for scraping off residual toner on an image carrier; and a squeeze sheet for guiding the scraped residual toner to a cleaning container; A cleaning member provided with a magnetic member adjacent to the cleaning blade at an exposed portion sandwiched between a portion where the cleaning blade contacts the image carrier and a portion where the squeeze sheet contacts the image carrier. 4. An image carrier, charging means for charging the image carrier to a predetermined potential, exposure means for forming an electrostatic latent image on the image carrier by exposing the image carrier, and Developing means for developing the electrostatic latent image using toner to form a toner image; transfer means for transferring the toner image from the image carrier to a transfer material; and cleaning means for cleaning residual toner on the image carrier 3. An image forming apparatus comprising: a fixing unit for fixing a toner image on a transfer material, wherein the cleaning unit comprises the cleaning unit according to claim 1 or 2. 5. An image bearing member, charging means for charging the image bearing member to a predetermined potential, exposure means for forming an electrostatic latent image on the image bearing member by exposing the image bearing member, and Developing means for developing the electrostatic latent image using toner to form a toner image; transfer means for transferring the toner image from the image carrier to a transfer material; and cleaning means for cleaning residual toner on the image carrier 4. An image forming apparatus comprising: a fixing unit for fixing a toner image on a transfer material, wherein the toner is a magnetic toner containing a magnetic material, and the cleaning unit is the cleaning unit according to claim 1, 2, or 3. An image forming apparatus comprising: