JPH02211484A - Image forming device - Google Patents

Abstract

PURPOSE:To stabilize image quality and to prolong the life of a photosensitive body by providing a cleaning means made of conductive resin, which has a specific electric resistance value, in plural stages and eliminating the influence of residual toner on the photosensitive body at the time of exposure. CONSTITUTION:A cleaning member 109 consists of a couple of brushes 135a and 135b formed of the conductive resin whose electric resistance value is 10<3> - 10<7>OMEGA. Further, the brush 135a is applied with a positive voltage and the brush 135b is applied with a negative voltage respectively. Then lump toner remaining on the photosensitive body 101 is attracted to the brush 135a or 135b according to the electrostatic charging state of the toner, pushed out backward, and stuck dispersedly on the photosensitive body 101. The brushes 135a and 135b are formed of soft members, so the photosensitive body is not flawed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus such as an electrophotographic laser printer or a copying machine, and in particular remains on an image carrier after transfer. The present invention relates to an improvement in a cleaning means for cleaning toner.

(Prior Art) Image forming apparatuses such as electrophotographic laser printers are equipped with a developing device that supplies toner to an electrostatic latent image formed on a cylindrical photoreceptor, which is an image carrier, to make it visible. A transfer device is provided for transferring an image formed on the photoreceptor using toner onto a sheet of paper. Although most of the toner on the photoreceptor is transferred onto the paper by this transfer device, some toner remains on the photoreceptor.

The remaining state of the toner on the photoreceptor after this transfer is as shown in FIG. 11, in which there are various remaining toner states, and in FIG. 8, A is the case where normal transfer has been performed.

B is a case where the transfer is close to normal, but the transfer is slightly excessive, and the toner becomes positively charged with the opposite polarity by the transfer charger, which tends to occur when transferring solid black etc.
In addition, C is a case where toner remains in a lump due to insufficient transfer, which tends to occur when the paper is lifted off the transfer body during transfer due to carrier adhesion or paper wrinkles.Additionally, toner remaining after transfer in unexposed areas is left on the surface of the photoreceptor. Since the potential Vo is lower than the developing bias vb applied to the developing device, ff51 is electrically attracted to the developing device. On the other hand, since the surface potential of the photoreceptor has increased due to exposure, the toner remaining after transfer in the exposed area does not return to the developing device and remains on the photoreceptor.

If the untransferred toner remaining on the photoconductor is uniformly scattered on the photoconductor as in cases A and B, the amount of laser light in the exposure process is sufficiently large;
Since the exposed area is sufficiently large compared to the size of the toner, even if toner adheres to the photoreceptor, it will not create a shadow from the exposure, and the negative potential on the surface of the photoreceptor will attenuate and a latent image will be formed. Ru. Moreover, as the unexposed area is reliably cleaned by the developing device as described above, there is no problem in forming a latent image. However, if toner remains in the form of a lump as in case C, This makes it difficult to clean everything, and positive memory is formed on the white background. Also, if this area corresponds to the next exposed area, the toner layer is thick and the diameter of the lump is large, so no light passes through, and the black background becomes Negative memory occurs.

In order to remove the above-described residual toner after transfer, a cleaner has conventionally been provided between the transfer device and the pre-exposure device on the outer periphery of the photoreceptor. Conventionally, this cleaner has been comprised of a blade that comes into contact with the surface of the photoreceptor to scrape off toner, and a collection box that collects the scraped off toner.

(Problems to be Solved by the Invention) However, according to the conventional cleaners as described above,
Since the toner remaining on the photoconductor is scraped off into the collection box with a blade, it usually takes 2,000 yen.
After making 3,000 to 3,000 copies, the toner in the collection box becomes full and becomes unusable. For this reason, a complicated collection mechanism and collection box must be installed and the collection box must be replaced each time to collect the toner, which not only complicates the structure but also makes the user's hands and hands dirty, resulting in poor work efficiency. There was a problem. Furthermore, depending on the type of equipment, the cleaner may have to be discarded each time. Furthermore, since the toner on the photoreceptor is scraped off by the blade, there is also the drawback that the surface of the photoreceptor is scratched.

The present invention was developed in view of the above circumstances, and has a simple structure that eliminates the influence of residual toner on the photoreceptor during exposure, stabilizes image quality, extends the life of the photoreceptor, and improves work efficiency. An object of the present invention is to provide an image forming apparatus that can improve performance.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention includes an image bearing member and a developing device configured integrally, and a cleaning means for cleaning toner remaining on the image bearing member after transfer. In the image forming apparatus, the cleaning means is configured in multiple stages, these cleaning means are made of conductive resin, and the electrical resistance value of the conductive resin is set to 103Ω to 107Ω. .

(Function) According to the means described in L, the lump-like toner remaining on @4 [i special holiday after transfer is temporarily electrostatically removed by applying a voltage of opposite polarity to the toner to multiple stages of cleaning means. It can be sucked and later dispersed to the rear, and it is possible to prevent memory generation due to residual toner during exposure. Therefore, a toner collection box is not required, and by integrally attaching the cleaning means to the developing device, it is possible to make the cartridge compact. Moreover, since the cleaning means is made of a soft material, the surface of the image carrier is not damaged, and the life of the image carrier can be extended.

(Embodiment) Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 to 3.

In FIGS. 1 and 2, one mag roller 131 and two stirring rollers 132a, 132b are provided in the casing 133 of the developing device 104, with their axial directions parallel to each other. arrows a and b respectively
, and are driven to rotate in the c direction. Further, the casing 133 is filled with toner 134 which is a developing device. A drum-shaped photoreceptor 101 is provided in this casing 133 in parallel to each of the rollers 131 and 132, and is rotated lN! in the direction of arrow R by a drive source (not shown). be moved.

Furthermore, a cleaning means 109 is provided in the casing 133 in parallel to the photoreceptor 101, and this cleaning means 109 is made of conductive rayon or the like as shown in FIG.
A pair of brushes 135a and 135b made of a soft material with a resistance of 4Ω to 106Ω are attached in parallel. The lower ends of these brushes 135a and 135b are in contact with the outer periphery of the photoreceptor 101 in the width direction along the generatrix direction, and the width is wider than the maximum paper width to be used and the image loading. One brush 135b is connected to a charger 10 which will be described later.
The other brush 135a is electrically connected to the second grid case and supplied with negative charge, and the other brush 135a is connected to the positive side of the power supply terminal of the device main body and supplied with positive charge. This connection may be reversed, and an insulating material such as a Mylar sheet (not shown) is provided between the brushes 135a and 135b to provide electrical insulation.

Note that the reference numeral 141 shown in FIG.
at super a form vLgto3 to a light body t.

1, the reference numeral 136 shown in FIG. 2 is a handle provided on the casing 133 of the developing device 104. will be explained with reference to FIG.

FIG. 4 shows a schematic configuration of an electrophotographic monochrome laser printer.

This laser printer is electrically connected to a computer or a host system (external device) such as a word processor via a transmission device (not shown), receives dot image data from the external device, and emits a laser beam. Writing is performed on the photoreceptor by writing, and the written dot/gamma image data is developed and transferred onto the paper 1.

That is, 100 is an apparatus main body, and a drum-shaped photoreceptor #101 is disposed within this main body 100, and this photoreceptor 101 is rotated in the direction of arrow R by a drive source (not shown).

Around the photoreceptor 101, a developing device 104, which is provided with a charge control type charging GT device 102, an NT latent image forming section 103, and the cleaning means 109, is provided along the rotation direction of the photoreceptor 101.
A transfer charger 05 and a pre-exposure device 112 are arranged next to each other, and a photosensitive member #101 is integrated with a developing device 104.

The main body 100 is provided with a paper feed cassette 106, and a paper feed roller 10 is provided from the paper feed cassette 106.
The paper as the recording body taken out in step 7 is transferred to the photoreceptor 10.
1 and the transfer charger 105, and the image transfer unit 1
After passing through 08 and a fixing device 118, the sheet is guided to a sheet discharge roller 113 and is discharged to a sheet discharge section 114.

The electrostatic latent image forming unit 103 includes a semiconductor laser oscillator (not shown) (such as a laser diode) that generates a laser beam modulated according to dot image data from an external device (not shown), and a laser output from this laser oscillator. A lens system (not shown) such as a collimator lens that focuses the beam light, a four-sided rotating mirror (polygon mirror) 116 that scans the laser beam focused by this lens system, and a high-speed rotating mirror 116. A rotating mirror motor 117, a lens 121 that correctly guides the laser beam scanned by the rotating mirror to the photoconductor, a reflecting mirror 119 that reflects the laser beam toward the photoconductor 101,
120, a beam photodetector (not shown) for detecting the laser beam scanned by the rotating mirror 116, and the like.

In such a configuration, when a print start signal is received from an external device, the photoreceptor 101 rotates and the photoreceptor 10
1 is uniformly IF charged by the charging IF'f4 device 102 so that the surface potential becomes e 600 V, for example.

Next, when receiving dot image data from an external device,
The nt latent image forming unit 103 outputs a laser beam modulated according to the dot image data, and the surface of the photoreceptor 101 which has been electrically charged is scanned and exposed by the laser beam light, whereby the surface of the photoreceptor 101 is exposed. Forms an electrostatic latent image on the surface. The electrostatic latent image formed on the photoreceptor 101 is reversely developed by a developing device 104 having a magnetic roller 131 and stirring rollers 132a and 132b, thereby becoming a toner image. The toner image on the photoreceptor 101 is then transferred onto a sheet of paper conveyed from the paper feed cassette 106 in an image transfer section 108 .

The paper onto which the toner image has been transferred is conveyed to a fixing device 118 where the toner image is fixed, and then ejected to a paper ejection section 114 by a paper ejection roller 113. Also, the transfer charger 105
After the toner image is transferred from the photoreceptor 101 to a sheet of paper (not shown), the toner remaining on the photoreceptor 101 is cleaned by the cleaning means 109 by the action described later, and then the light source of the pre-exposure device 112 such as a red LED is removed. The surface of the photoreceptor 101 is uniformly neutralized by the light emitted from the photoreceptor 101 .

Next, the action of the cleaning means 109 is explained in FIGS. 5 to 10.
This will be explained with reference to the figures.

5 to 7 show the case of insufficiently transferred toner, and FIGS. 8 to 10 show the case of excessively transferred toner, and when positive and negative voltages are applied to the two brushes 135a and 135b, respectively. do.

If there is a toner mass 150 on the surface of the photoreceptor 101 moving in the direction of arrow X as shown in FIG.
50 sweeps 3131% under the brush 135a, the toner mass 150 having a negative charge due to insufficient transfer is attracted to the brush 135a to which a positive voltage is applied.

As the photoreceptor 101 further moves in the direction of the arrow X, the toner mass 150 sucked by the brush 135a
Since the toner a does not have the ability to hold toner, it naturally comes out behind the brush 135a as shown in FIG. That is, the brush 135a attracts n of the insufficiently transferred toner mass 150 with force, but since the amount of toner that can adhere to the brush 135a is small, and because the brush 135a is in contact with the photoreceptor 101 in the width direction, - anti-suction Toner 150
gradually adheres to other parts of the surface of the photoreceptor 101. At this time, since a negative voltage is applied to the other brush 135b, the toner mass 150 having a negative charge
is not attracted by the brush 135b, but is agitated by the brush 135b'''C' and dispersed on the surface of the photoreceptor 101, as shown in FIG.

On the other hand, in the case of excessively transferred toner, 1. As shown in FIG. 8, the toner 151 is uniformly scattered on the transfer body 101 and has reversed polarity, and has the same positive polarity as the brush 135a. Therefore, even if the photoreceptor 101 moves in the direction of arrow X and passes under the brush 135a as shown in FIG. 9, it will not be attracted and will continue to be attracted to the photoreceptor 101.
When it reaches the bottom of the other brush 135b, a negative voltage is applied to this brush 135b, so
The toner 151 having a positive charge is temporarily attracted by the brush 135b and is dispersed and attached to the photosensitive member #101 as shown in FIG. 10, as in the case described above. At this time, since the brush 135 is made of a soft material and is in contact with the photoreceptor 101 in the quiz direction, that is, in a state of belly contact, and the contact pressure is extremely weak, the toner 151 is not moved. 151 is uniformly scattered, which is the initial state.

According to this embodiment, the transfer residual toner 1 on the photoreceptor 101
50 and 151 are uniformly scattered after passing under the brush 135, and it is possible to prevent the occurrence of memory due to residual toner during exposure. Therefore, there is no need for a conventional toner collection box, and the transfer body 101,
The developing device 104 and the memory removing means 109 can be integrated into a cartridge, making it possible to reduce the size and weight of the device. Further, since the brush 135 is made of a soft material and is in contact with the photoreceptor 101 in the quiz direction, the brush 135 is
It can extend its lifespan and improve image quality without damaging it.

In the above embodiment, the cleaning means 109 is provided with two brushes 135. However, the number of brushes 135 may be three or more, and the material and shape of the brushes 135 may be Any resin is sufficient,
It is not limited to what is shown in this example.

〔Effect of the invention〕

As described above, according to the present invention, the lump-like toner remaining on the image bearing member after transfer is removed by conductive v
Since the toner is temporarily electrostatically attracted by the cleaning means made of A fat and then dispersed onto the image carrier, it is possible to prevent the occurrence of memory caused by lumps of residual toner remaining on the image carrier. This eliminates the need for a toner collection box, makes it possible to make the apparatus smaller and lighter by using a cartridge, and also extends the life of the image carrier and improves the quality of images.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing essential parts of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view of FIG. 1, and FIG.
FIG. 4 is a longitudinal sectional view showing a laser printer to which the cleaning device according to the present embodiment is applied, and FIGS. 5 to 10 are explanatory diagrams showing the operation of the present embodiment. , FIG. 11 is an explanatory diagram showing toner remaining on the image carrier. 101...photoreceptor (image carrier). 104...Developer. 109...Cleaning means. 150.151...Toner

Claims (1)

[Claims] An image forming apparatus in which an image bearing member and a developing device are integrally constituted, and a cleaning means is provided for cleaning toner remaining on the image bearing member after transfer, the cleaning means being configured in a plurality of stages, An image forming apparatus characterized in that these cleaning means are made of a conductive resin, and the electrical resistance value of the conductive resin is set to 10^3Ω to 10^7Ω.