JPH0580676A - Cleaner for image forming device - Google Patents

Abstract

PURPOSE:To provide a cleaner for an image forming device which uses only a cleaning brush in a monochromatic image formation mode so that the lifespan of a cleaning blade is lengthened and enhances the plural-color toner removal performance in superimposed plural-color image formation. CONSTITUTION:The cleaning brush 4 to which a bias voltage is impressed for clearing up residual toner T is provided in such a manner that it rotates while sliding against a photosensitive body 1. The device is provided with the cleaning blade 6 which removes the toner T in co-operation with the cleaning brush 4 at the time of forming a color image and is separated from the photosensitive body 1 to carry out cleaning by the use of only the cleaning brush 4 at the time of forming a monochromatic image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for an image forming apparatus using a cleaning brush or a cleaning blade.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile or a printer, an electrostatic latent image is formed on a latent image carrier, and the electrostatic latent image is visualized as a toner image. After the transfer of the image, the toner that has not contributed to the transfer remains on the surface of the latent image carrier, so that the toner is removed from the latent image carrier and collected. As a cleaning device which achieves such a function, a cleaning device using a cleaning brush and a cleaning blade is widely used in this type of image forming apparatus.

In this type of cleaning device, generally, a predetermined cleaning bias voltage is applied to the cleaning brush to electrostatically adsorb the residual toner on the latent image carrier to the brush side. The residual toner that has not been broken is scraped off with a cleaning blade.

By the way, an image forming apparatus of this type can execute both a mode for forming an image of a single color (for example, a black image) and a mode for forming an overlapping image of a plurality of colors (color image). There is something.

When executing the mode for forming a superposed image of a plurality of colors, a plurality of developing devices arranged around the latent image carrier are operated to directly form toner images of different colors on the surface of the latent image carrier. Overlapping images are formed to form multiple-color overlaid images on the surface of the latent image carrier.However, since the toner of each color used in each developing device has different characteristics such as the dielectric constant, the cleaning brush is used. If the bias voltage to be applied is set to, for example, a bias voltage adapted to remove black toner, it may not be possible to remove toner of other colors by the cleaning brush. If both the cleaning brush and the cleaning blade are made to work when executing the mode for forming a superimposed image of a plurality of colors, the cleaning blade can remove the toner that could not be removed by the cleaning brush.

On the other hand, when the monochromatic image forming mode is executed, if a bias voltage capable of electrostatically attracting the monochromatic residual toner is applied to the cleaning brush, the toner can be removed by the cleaning brush. This may be separated from the latent image carrier so that the cleaning blade does not work. In this case, the contact time of the cleaning blade is shortened and the life of the cleaning blade can be extended.

Conventionally, such a cleaning blade is
Regardless of which of the two modes is selected, the cleaning blade remains in contact with the latent image carrier and the life of the cleaning blade is shortened.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to use only a cleaning brush when executing a monochromatic image forming mode, or to weaken the contact force of a cleaning blade with respect to a latent image carrier, It is an object of the present invention to provide a cleaning device for an image forming apparatus, which is capable of extending the life of the cleaning blade and enhancing the removability of the toners of a plurality of colors when executing the overlapping image forming mode of a plurality of colors.

[0009]

In order to achieve the above object, the present invention is rotated so as to rub against the surface of a latent image bearing member, and remains on the surface of the latent image bearing member after the toner image transfer step. A cleaning brush that electrostatically adsorbs the remaining toner,
A cleaning blade is provided downstream of the cleaning brush in the moving direction of the surface of the latent image carrier to scrape off and remove residual toner on the surface of the latent image carrier, and a monochrome image is formed on the latent image carrier. When executing the mode, the cleaning blade is separated from the latent image carrier to remove the monochromatic toner only with the cleaning brush.
A cleaning blade that brings the cleaning blade into contact with the latent image carrier in order to remove the toners of the multiple colors in cooperation with the cleaning brush when executing a mode of forming a superimposed image of a plurality of colors on the latent image carrier. The present invention proposes a cleaning device for an image forming apparatus, which is provided with a separation / contact driving means.

Similarly, a cleaning brush that rotates so as to rub against the surface of the latent image carrier and electrostatically adsorbs the toner remaining on the surface of the latent image carrier after the toner image transfer step, A cleaning blade which is provided on the downstream side in the moving direction of the latent image carrier surface with respect to the cleaning brush and scrapes off and removes the residual toner on the latent image carrier surface.
When executing the mode for forming a superposed image of a plurality of colors on the latent image carrier, the cleaning blade is brought into contact with the latent image carrier to remove the toner of a plurality of colors in cooperation with the cleaning brush, and the latent image carrier is When the mode for forming a single-color image on the image carrier is executed, the cleaning blade contact that weakens the contact force of the cleaning blade on the latent image carrier is executed more than when the mode for forming a superimposed image of a plurality of colors is executed. A cleaning device for an image forming apparatus including a contact force adjusting unit is proposed.

When the mode for forming a superposed image of a plurality of colors is executed, it is assumed that the cleaning brush is applied with a bias voltage that enables electrostatic attraction of the toner charged by the cleaning brush. It is effective.

Further, when the image forming mode of the cleaning blade is switched from the superposed image forming mode of a plurality of colors to the monochromatic image forming mode, a plurality of images of different colors are formed on the latent image carrier. It is effective that the surface area of the latent image carrier facing the developing device is separated from the latent image carrier after passing through the cleaning blade.

Further, when the image forming mode of the cleaning blade is switched from the superposed image forming mode of a plurality of colors to the single color image forming mode, a plurality of images for forming different colors on the latent image carrier are formed. It is effective that the surface area of the latent image carrier facing the developing device can weaken the contact force with respect to the latent image carrier after passing through the cleaning blade.

[0014]

The present invention will be described in detail below with reference to the illustrated embodiments.

In FIG. 1, reference numeral 1 denotes a drum-shaped photosensitive member which is an example of a latent image carrier, and the photosensitive member 1 is rotationally driven in the direction of the arrow by a driving device (not shown). A plurality of, in the illustrated example, four developing devices 2Y, 2M, 2C and 2Bk are arranged around the photoconductor 1 so as to be adjacent to each other.

As is well known, the surface of the photoconductor 1 is charged,
Exposure or the like is performed to form an electrostatic latent image. When executing the monochromatic image forming mode, one of the developing units,
For example, the black developing device 2Bk operates to visualize the electrostatic latent image with black toner. This visible image is transferred to a transfer paper (not shown), and the transfer image on the transfer paper is fixed, whereby a copy paper with a black image is obtained when the image forming apparatus is a copying machine.

On the other hand, when executing the superimposed image forming mode of a plurality of colors, the yellow developing device 2Y, the magenta developing device 2M,
The cyan developing device 2C and the black developing device 2Bk work respectively to form toner images of different colors on the surface of the photoconductor in a superimposed manner, and a superposed image of a plurality of colors is directly formed on the surface of the photoconductor 1. By transferring such a color image on the transfer paper and fixing the transferred image,
A copy paper of a color image can be obtained. In this mode, there is also an image forming apparatus configured such that the black developing device 2Bk does not work.

As described above, the illustrated image forming apparatus directly forms toner images of different colors on the photoconductor 1, sequentially forms monochromatic toner images on the photoconductor, and the respective toner images are formed. The method of forming a toner image on a photoconductor is different from that of an image forming apparatus that sequentially transfers the toner images onto the same transfer paper to obtain a color image.

In the monochromatic image forming mode, monochromatic toner, for example, black toner remains on the surface of the photoconductor 1 after the toner image transfer step. Further, in the case of a multi-color superimposing image forming mode, four color toners remain on the surface after the toner image transfer process. Some of such residual toner may be charged to the opposite polarity during the transfer process or the like. Therefore, in order to facilitate removal of such toner, the pre-cleaning charger 3 removes the toner. It is charged to its original polarity, and its charge amount is also uniform. In addition, in FIG. 1, the residual toner on the photoconductor 1 is schematically shown in an enlarged manner, and the symbol T is attached to this.

A cleaning brush 4 is provided on the downstream side of the pre-cleaning charger 3 in the moving direction of the surface of the photosensitive member 1. The cleaning brush 4 is arranged in the direction of the arrow shown in the drawing so as to slide on the surface of the photosensitive member 1. It is designed to be driven to rotate. The cleaning brush 4 includes, for example, a conductive brush (fiber) and a conductive shaft center that fixedly supports the base end side of the brush. A voltage is applied. By this application, while the cleaning brush 4 slides on the surface of the photoconductor 1, the residual toner T on the photoconductor 1 is scraped off and electrostatically adsorbed on the brush side.

For the cleaning brush 4, the photosensitive member 1
A cleaning blade 6 made of an elastic material such as rubber is provided on the downstream side of the surface in the moving direction. The cleaning blade 6 extends in the axial direction of the photoconductor 1 and is fixed to the blade support member 7. The blade support member 7 is swingably supported around the center of the support shaft 8.

A solenoid 9 is connected to the blade supporting member 7, and when the solenoid 9 is excited, the blade supporting member 7 rotates around the support shaft 8 in the clockwise direction in the drawing, so that the cleaning blade 6 moves. As shown in FIG. 2, it is separated from the photoconductor 1. When the solenoid 9 is not excited, the force of the tension spring 10 causes the cleaning blade 6 to come into contact with the photoconductor 1 at a predetermined pressure to scrape and remove the toner on the photoconductor. Blade support member 7, support shaft 8, solenoid 9, and tension spring 10
Is a cleaning blade separation / contact driving means for bringing the cleaning blade 6 into contact with the photosensitive member 1 or separating the cleaning blade 6 from the photosensitive member. ,
The cleaning brush 4 and the cleaning blade 6 are provided.

Here, when executing the mode for forming a monochrome image on the photoconductor, the solenoid 9 is excited to rotate the blade support member 7 clockwise in the drawing, and the force of the spring 10 causes the photoconductor 1 to rotate. As shown in FIG. 2, the cleaning blade 6 that has been pressed against is separated from the surface of the photoconductor 1. That is, the residual toner on the photoconductor 1 is removed only by the cleaning brush 4.

First, the pre-cleaning charger 3 sets an amount of electric charge that makes it easy for the cleaning brush 4 to remove a monochromatic residual toner, for example, black toner. That is, the mass ratio of the residual toner to the charge is kept within a certain range. If a bias voltage is applied to the cleaning brush 4 so that the residual toner having such a charge amount can be electrostatically favorably adsorbed, the cleaning brush 4 is assisted without the assistance of the cleaning blade 6. Only, the residual toner of a single color can be removed. That is, when the user of the image forming apparatus selects the monochromatic image forming mode, the bias applied to the cleaning brush 4 is set to a value capable of removing the residual toner whose charge-to-charge mass ratio is controlled by the pre-cleaning charger 3. However, the residual toner is removed only by the cleaning brush 4.

However, when the mode for forming a superposed image of a plurality of colors is executed, it is not as simple as this. For example, assuming that the monochrome toner is black toner, the cleaning brush 4 is conventionally used for this removal.
For example, a cleaning bias voltage of about -300V to + 300V is applied. On the other hand, for example, to remove the magenta toner, which is the color toner, for example, +500
A cleaning bias voltage of about V to +1000 V has been applied to the cleaning brush. This is because the dielectric constant of the toner varies depending on the type of toner. In the case of multi-color overlay image formation mode,
If the cleaning is performed under the latter cleaning bias voltage condition, the former black toner may not be removed by the cleaning brush 4. Thus, when the multi-color superimposing image forming mode is executed, it is not possible to remove all the multi-color residual toner with the cleaning brush 4 alone.

Therefore, in the superimposed image mode of a plurality of colors,
The excitation of the solenoid 9 is turned off, and the cleaning blade 6 is pressed against the surface of the photoconductor 1 with a predetermined pressure by the force of the tension spring 10. Both the cleaning blade 6 and the cleaning brush 4 remove the residual toner on the photoconductor. Remove.

At this time, a group of toners having similar characteristics is applied to the cleaning brush 4 as a bias voltage for relatively evenly removing the toners of this group, and the cleaning brushes 4 which are characteristically separated from each other. If the cleaning blade 6 removes the residual toner of another group that is difficult to remove, both residual toners can be removed in general. That is, on the cleaning brush 4 side, the condition of the bias voltage applied to the cleaning brush 4 may be matched to the toner to be removed. The cleaning brush 4 and the cleaning blade 6 remove the residual toners of a plurality of colors, respectively, and at this time, a bias voltage is applied to the cleaning brush 4 to enable electrostatic attraction of the toner in charge thereof. To be done. By doing so, the cleaning brush 4 and the cleaning blade 6 complement each other, and it is possible to satisfactorily remove residual toner having different characteristics. Further, at this time, by selecting the bias voltage to the cleaning brush 4 so that the most frequently used toner is removed by the cleaning brush 4, it is possible to further improve the cleaning property of the residual toner.

By the way, this kind of toner may have different particle diameters depending on the kind. In particular, it is currently difficult to remove the toner having a small particle diameter by the cleaning blade 6. In such a case, a bias voltage suitable for removing the residual toner having a small particle size is applied to the cleaning brush 4, such a toner is removed by the cleaning brush 4, and the residual toner having a relatively large particle size is cleaned. It may be removed by the blade 6.
It is also possible to select the particle size of the toner in advance and remove the easily removable toner by the cleaning brush 4 and the cleaning blade 6, respectively. Even in such a case, as in the above-described example, the cleaning brush 4 is applied with a bias voltage that matches the residual toner to be removed. Since the DC bias voltage power source 5 is a variable voltage power source, it is extremely easy to match the applied bias voltage to the toner to be removed.

In any case, when the multi-color overlapping image forming mode is executed, the cleaning brush 4 and the cleaning blade 6 cooperate with each other to remove the residual toners of multiple colors.

In a cleaning device using this type of cleaning blade, if the cleaning blade is in contact with the photosensitive member, the edge of the cleaning blade may become worn or chipped over time. , Its life tends to be shortened. In this example, since the cleaning blade 6 is separated from the photoconductor 1 when the monochromatic image forming mode is executed, the life of the cleaning blade can be extended.

When the single-color image forming mode is executed, the contact force of the cleaning blade 6 with respect to the photosensitive member 1 is set to be larger than that when the multi-color image forming mode is executed without completely separating the cleaning blade 6 from the photosensitive member 1. You may also weaken. The cleaning brush 4 has a large amount of toner coming into the cleaning brush 4, or the like.
If the toner is not completely removed by the above method, the cleaning blade 6 is brought into contact with the surface of the photoconductor 1 with a light force, and a relatively small amount of the toner which cannot be completely removed is removed by the cleaning blade. It can be removed in 6.

In the state shown in FIG. 1, the cleaning blade 6 is strongly pressed against the surface of the photoconductor 1 by the force of the spring 10,
It is in a bent state. When executing the single-color image forming mode, the blade support member 7 is rotated clockwise around the center of the support shaft 8 by the excitation of the solenoid 9.
At this time, the above-described operation can be obtained by restricting the rotation amount of the blade support member 7 to such an extent that the cleaning blade 6 comes into light contact with the photoconductor 1. Figure 3
In the above, reference numeral 12 is a stopper for regulating the rotation amount thereof. In this case, the pressure contact force of the cleaning blade 6 is significantly reduced, so that the load applied to the edge portion can be reduced and the life of the cleaning blade 6 can be extended.

As described above, in this embodiment, the solenoid 9, the tension spring 10, the blade supporting member 7, the support shaft 8 and the stopper 1 are provided.
2 makes the cleaning blade 6 contact the photoconductor 1 in the multi-color overlapping image forming mode, and in the single-color image forming mode, the contact force of the cleaning blade 6 with respect to the photo conductor 1 is larger than that in the multi-color overlapping image forming mode. It constitutes a cleaning blade contact force adjusting means for weakening.

By the way, as shown in FIG. 1, four developing devices 2Y, 2MM, 2C and 2Bk are arranged around the photoconductor 1, but these developing devices are not shown. Although not provided, a developer carrying member such as a developing sleeve facing the photoconductor 1 is provided, and the toner of each color conveyed on the peripheral surface thereof is electrostatically attached to the surface of the photoconductor 1 during development. To move to.

When the image forming mode is switched from the multi-color superimposing image forming mode to the single color image forming mode, the regions of the surface of the photoreceptor on which the developer carrying members of the four developing devices face each other, After passing through the cleaning blade 6, the cleaning blade 6 is separated from the photoconductor 1 (FIG. 2), or the contact force of the cleaning blade 6 with respect to the photoconductor 1 is weakened (FIG. 3). In this removal state, it is possible to proceed to the step of removing the single-color toner with only the cleaning brush 4. On the other hand, if the cleaning blade 6 is separated from the photoconductor or the contact force of the cleaning blade 6 with respect to the photoconductor 1 is weakened before the region passes, the region from the photoconductor surface position at this point to Between the end of
Since the toners of a plurality of colors remain, such a residual toner may not be able to be removed independently at the cleaning brush 4 in the single-color image forming mode.

[0036]

According to the cleaning device of the first aspect of the present invention, it is possible to enhance the removability of toners of a plurality of colors and extend the life of the cleaning blade.

According to the cleaning device of the second aspect, in addition to the above-mentioned effects, in the single-color image forming mode, the residual toner which cannot be completely removed by the cleaning brush is lightly brought into contact with the latent image carrier. It can be removed by the above method, and its cleaning property can be further enhanced.

According to the cleaning device of the third aspect, the bias applied to the cleaning brush is adjusted to the condition of the residual toner to be removed by the cleaning brush in the mode for forming the superposed images of a plurality of colors. It is possible to satisfactorily remove a plurality of color toners having different characteristics such as a rate.

According to the cleaning device of the fourth and fifth aspects, the plural color toners remaining on the latent image carrier can be generally removed in the plural color superimposing image forming mode. It is possible to enter the monochromatic image forming mode without leaving any toner.

[Brief description of drawings]

FIG. 1 is a configuration diagram around a photosensitive member of an image forming apparatus including a cleaning device according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a cleaning blade included in the cleaning device according to the exemplary embodiment of the present invention is separated from the photoconductor.

FIG. 3 is a diagram showing a state in which the pressure contact force of the cleaning blade included in the cleaning device according to the exemplary embodiment of the present invention with respect to the photoconductor is weakened.

[Explanation of symbols]

 1 Drum-Shaped Photoreceptor as Latent Image Carrier 2Y Developing Device 2M Developing Device 2C Developing Device 2Bk Developing Device 4 Cleaning Brush 6 Cleaning Blade T Toner

Claims (5)

[Claims] 1. A cleaning brush, which rotates so as to rub against the surface of the latent image carrier and electrostatically adsorbs toner remaining on the surface of the latent image carrier after the toner image transfer step, A cleaning blade provided downstream of the cleaning brush in the moving direction of the surface of the latent image carrier to scrape off and remove residual toner on the surface of the latent image carrier, and a monochromatic image is formed on the latent image carrier. When the mode is executed, the cleaning blade is separated from the latent image carrier in order to remove the monochromatic toner only with the cleaning brush, and when the mode for forming a superimposed image of a plurality of colors on the latent image carrier is executed, In order to remove the toners of a plurality of colors in cooperation with the cleaning brush, the cleaning blade is provided with a cleaning blade contact / separation drive unit that contacts the latent image carrier. A cleaning device for the image forming apparatus. 2. A cleaning brush that rotates so as to rub against the surface of the latent image carrier and electrostatically adsorbs the toner remaining on the surface of the latent image carrier after the toner image transfer step. A cleaning blade is provided downstream of the cleaning brush in the moving direction of the surface of the latent image carrier to scrape off and remove residual toner on the surface of the latent image carrier, and a superimposed image of multiple colors is formed on the latent image carrier. When executing the formation mode, a mode in which a cleaning blade is brought into contact with the latent image carrier to remove toners of a plurality of colors in cooperation with the cleaning brush, and a monochrome image is formed on the latent image carrier. The cleaning blade contact force adjusting means for weakening the contact force of the cleaning blade with respect to the latent image carrier is used when performing A cleaning device for an image forming apparatus, comprising: 3. A cleaning brush is applied with a bias voltage that enables electrostatic attraction of toner charged by the cleaning brush when executing a mode for forming a superimposed image of a plurality of colors. The cleaning device for an image forming apparatus according to claim 1. 4. The cleaning blade comprises a plurality of cleaning blades for forming images of different colors on the latent image carrier when the image forming mode is switched from the overlapping image forming mode of a plurality of colors to the single color image forming mode. 4. The cleaning device for an image forming apparatus according to claim 1, wherein the surface area of the latent image carrier opposite to the developing device is separated from the latent image carrier after passing through the cleaning blade. 5. The cleaning blade comprises a plurality of cleaning blades for forming images of different colors on the latent image carrier when the image forming mode is switched from the overlapping image forming mode of a plurality of colors to the single color image forming mode. 3. The cleaning device for an image forming apparatus according to claim 2, wherein the surface area of the latent image carrier on which the developing device is opposed can weaken the contact force with respect to the latent image carrier after passing through the cleaning blade.