JPH0887177A - Electrophotographic device - Google Patents

Abstract

PURPOSE: To provide an electrophotgraphic device capable of preventing the deterioration of image affected by the paper dust of a recording paper. CONSTITUTION: In the device provided with the photoreceptor 31, the electrifying device 32, the exposure device 33 for forming the electrostatic latent image on the photoreceptor 31, the developing device 34 for forming the toner image by holding the developing roller 37 carrying the toner having the same polarity as the potential by electrification in contact with the photoreceptor 31 and the transfer device 35 for transferring the toner image to the recording medium by holding the transfer roller 40 applied the voltage in contact with the photoreceptor while interposing the recording medium in between the both, the toner remaining on the photoreceptor 31 is recovered to the developing device 34 by the developing roller 37 of the developing device 34; the brush 41 having a brush face held in contact with the surface of photoreceptor 31 as well as the brush face moved together with the move of the surface of photoreceptor 31 is disposed between the transfer device 35 and the electrifying device 32.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic apparatus.

[0002]

2. Description of the Related Art An electrophotographic apparatus used in a facsimile apparatus or a printer apparatus generally has a structure described below. That is, a charging device that charges the surface of the photoconductor around the endless photoconductor, and an electrostatic latent image is formed on the surface of the photoconductor located downstream of the charging device in the rotation direction of the photoconductor. An exposure device and a developing device that applies toner carried by a developing roller, which is located on the downstream side of the exposure device in the rotation direction of the photoconductor, to the surface of the photoconductor to visualize the electrostatic latent image and form a toner image. An apparatus, a transfer device located downstream of the developing device in the rotation direction of the photoconductor and transferring the toner image of the photoconductor to a recording sheet as a recording medium, and a transfer device downstream of the transfer device in the rotation direction of the photoconductor. And a cleaning device which is located on the side and contacts the blade with the surface of the photoconductor to remove the toner remaining on the surface of the photoconductor after the transfer.

In the electrophotographic apparatus having this structure, the photosensitive member is rotated during image formation, the photosensitive member is charged by the charging device in accordance with the rotation, the electrostatic latent image is then formed by the exposure device, and then the developing device is formed. A toner image is formed.
Next, the toner image on the photoconductor is transferred to the recording paper by the transfer device, and the toner remaining on the photoconductor is removed by the cleaning device. The toner removed by the cleaning device is collected and discarded as waste toner.

However, such an electrophotographic apparatus is large in size because it is equipped with a cleaning device, and it is uneconomical to discard the toner collected by the cleaning device, and the cleaning device is required to discard the toner. There is a problem that the maintenance management of is complicated.

Therefore, in order to solve this problem, in recent years,
An electrophotographic apparatus disclosed in JP-A-59-133573 has been proposed. This electrophotographic apparatus is of a type having a function of performing both the developing process and the cleaning process at the same time, and as shown in FIG. 4, a hopper 3 containing toner T and two developing devices around the photoconductor 1 are provided. A two-component reversal developing type developing device 2 having rollers 4 and 5 is provided. In the developing device 2, the toner T is moved from the developing roller 4 to the photoconductor 1 for development, and at the same time, the toner remaining on the surface of the photoconductor 1 is sucked by the developing roller 3 for cleaning. The residual toner is collected by the developing device 2 and used again for development.

This electrophotographic apparatus is economical because the cleaning apparatus is omitted and the apparatus is downsized, and it is not necessary to discard the residual toner. However, since this electrophotographic apparatus adopts the two-component reversal development method, there is a problem that the developing apparatus itself is large and it is difficult to reduce the size and cost.

To solve this problem, an electrophotographic apparatus disclosed in Japanese Patent Laid-Open No. 62-203182 has been proposed. This electrophotographic apparatus adopts a non-contact one-component reversal development method and simultaneously performs both the developing step and the cleaning step. As shown in FIG. A developing device 12 adopting a reversal developing method is provided, and the developing device 12 has a hopper 13 in which the non-magnetic one-component toner T is accommodated and a developing roller 14 provided apart from the photoconductor 11. ing. In this developing device 12, toner is applied to the developing roller 14
Is transferred to the photoconductor 11 for development,
Toner remaining on the surface of the photoconductor 11 is sucked from the photoconductor 11 to the developing roller 14 for cleaning.

This electrophotographic apparatus can reduce the size of the developing device 12 by adopting the non-contact one-component reversal developing method. However, in this electrophotographic apparatus, since the photoconductor 11 and the developing roller 15 are separated from each other in a non-contact manner, the toner remaining on the photoconductor 11 is removed by the developing roller 14.
However, there is a problem that the efficiency of recovery is low.

To solve this problem, an electrophotographic apparatus disclosed in Japanese Patent Laid-Open No. 3-4276 has been proposed. This electrophotographic apparatus adopts a contact type one-component reversal developing method and simultaneously performs both the developing step and the cleaning step. As shown in FIG.
Development device 2 that uses the one-component reversal development method
2 is provided, and the developing device 22 has a hopper 23 that stores the one-component toner T and a developing roller 24 that contacts the photoconductor 21. In this developing device 22,
The toner moves from the developing roller 24 to the photoconductor 21 for developing, and the toner remaining on the surface of the photoconductor 21 is sucked by the developing roller 24 for cleaning.

Further, this electrophotographic apparatus is provided with a transfer roller as a transfer device, which is in contact with the photoconductor 21 and presses the recording paper P from the back side to bring it into contact with the photoconductor.
A contact type transfer device 25 for transferring the toner image formed on the photoconductor 21 to the recording paper P is provided.

In this electrophotographic apparatus, since the photoconductor 21 and the developing roller 24 are in contact with each other, the efficiency with which the developing device 22 collects the toner remaining on the photoconductor 11 is improved. However, in the electrophotographic apparatus of this system, when the negatively charged toner is used for the negatively charged photoreceptor, when the photoreceptor 21 and the recording paper P come into contact with each other in the transfer device 25, the recording paper P The paper dust generated from the toner adheres to the photoconductor 21 together with the residual toner after the transfer process.

Here, the talc contained in the paper powder component is easily negatively charged, that is, the counter material is easily positively charged. When this talc adheres to the photoconductor and is conveyed to the developing device and is collected in the hopper together with the residual toner in the developing device 22, the negative toner stored in the hopper is positively charged. Then, when the development is performed using this positive polarity toner, there arises a problem that the toner adheres to the non-image portion, that is, a stain called "fog" occurs and the image quality of the image is deteriorated.

Further, in the case where the developing device is of a type in which the toner carried on the developing roller is frictionally charged by the blade, paper dust is clogged between the developing roller and the blade, and streaks are generated in the image, resulting in image quality of the image. May decrease.

Particularly in the system in which the transfer device makes the transfer roller contact the photoconductor, the toner image on the photoconductor is transferred to the recording medium while moving the recording paper as the recording medium between them. Since the amount of the paper dust adhered to the photoconductor is large, the above-mentioned problem of image deterioration is remarkable.

[0015]

As described above, in the electrophotographic layer adopting the combination of the one-component contact reversal developing method, the residual toner collecting method by the developing device, and the contact transfer method, the recording paper sheet is used. There is a problem in that the image quality of an image is deteriorated due to stains called “fog” due to the influence of powder.

The present invention has been made in view of the above circumstances, and is one in which a one-component contact reversal development method, a residual toner recovery method by a developing device, and a contact transfer method are adopted in combination, due to the influence of paper dust of recording paper. It is an object of the present invention to provide an electrophotographic apparatus that prevents image deterioration.

[0017]

In order to achieve the above-mentioned object, an electrophotographic apparatus of the present invention comprises a photosensitive member which is formed of a positively charged photoconductive member and which is rotated during image formation, and this photosensitive member. A charging device for charging the surface of the photosensitive member to a positive polarity, an exposure device positioned downstream of the charging device in the rotation direction of the photoconductor to form an electrostatic latent image on the surface of the photoconductor, and the exposure device. On the other hand, a developing roller, which is located on the downstream side in the rotation direction of the photoconductor and carries a toner having the same polarity as the charging potential, is brought into contact with the surface of the photoconductor to adhere the toner to the photoconductor and thereby the electrostatic latent image. And a developing device that forms a toner image by exposing the developing device to the developing device, and is positioned downstream of the developing device in the rotation direction of the photoconductor to apply a voltage to contact the photoconductor and press the recording paper from the back side. Equipped with a transfer roller that contacts the photoconductor A transfer device for transferring a toner image formed on a photoconductor onto a recording sheet, wherein the developing roller of the developing device develops the toner remaining on the surface of the photoconductor after passing through the transfer device. In the electrophotographic apparatus to be collected by the apparatus, a brush whose brush surface comes into contact with the surface of the photoconductor and moves together with the movement of the surface of the photoconductor is provided between the transfer device and the charging device. And Further, the brush has a characteristic ranging from conductive to medium resistance, and a voltage is applied.

[0018]

With the above structure, the brush surface of the brush provided between the transfer device and the charging device is brought into contact with the surface of the photoconductor,
The brush surface of the brush moves along with the movement of the surface of the photoconductor during photo recording, so that the paper dust of the recording paper adhered to the surface of the photoconductor after the transfer process is removed from the photoconductor. Then, by forming a brush having a characteristic ranging from conductive to medium resistance and applying a voltage, the paper dust of the photoconductor can be removed more firmly.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic structure of an electrophotographic apparatus. In the figure, reference numeral 31 denotes an endless, for example, drum-shaped photosensitive member, which is formed of a positively charged photoconductive member such as aluminum. The photoconductor 31 is rotatably supported by a member (not shown) and is rotated by a rotation drive mechanism (not shown). Around the photoconductor 31, a charging device 32, an exposure device 33, a developing device 34, and a transfer device 3 are provided.
5 are arranged respectively, and these respective devices 32 to 34 are supported by members (not shown).

The charging device 32 charges the surface (outer peripheral surface) of the photoconductor 31 to a positive polarity, and is composed of a scorotron charger to which a voltage is applied from the DC power source E1. The exposure device 33 forms an electrostatic latent image on the surface of the photoconductor 31, and is composed of, for example, a light emitting diode (LED) exposure device, and is located downstream of the charging device 32 in the rotation direction of the photoconductor 3. There is.

The developing device 34 employs a one-component contact reversal developing method to visualize the electrostatic latent image on the surface of the photoconductor 31 to form a toner image. It is located on the downstream side in the rotation direction of 31. The developing device 34 includes a toner hopper 36 containing a one-component toner T, a developing roller 37 arranged in parallel with the photoconductor 31 and rotatably provided, the surface of which is in contact with the surface of the photoconductor 31. A toner supply roller 38, which is arranged parallel to the developing roller 37 and is rotatably provided, and a developing roller 3 which is stationary and provided at a fixed position parallel to the developing roller 37.
7 and a blade 39 that contacts the surface. The developing roller 37 and the supply roller 38 are rotated in the direction of the arrow in the drawing by a rotation driving device (not shown), and a voltage is applied by the DC power source E2.

The developing device 34 also has a function of performing a cleaning action of collecting the toner T remaining on the surface of the photoconductor 31 which has been fixed. The transfer device 35 is located on the downstream side in the rotation direction of the photoconductor 31 and has a transfer roller 40 that contacts the surface of the photoconductor 31. This transfer roller 4
0 is rotated in the direction of the arrow in the drawing by a rotation driving device (not shown), and a voltage is applied by the DC power supply E3.

A rotary brush 41 for removing the paper dust adhering to the photoconductor 31 is provided between the transfer device 35 and the charging device 32 at a position close to the photoconductor 31. Is a shaft 42 having the same length as that of the photoconductor 31 and a large number of brush bristles 43 radially arranged in the entire circumferential direction. This brush bristles 4
It is preferable to plant 3 so as to be in contact with the entire surface of the photoconductor 31 in the axial direction, but it may be partially planted with a predetermined width in the axial direction. The brush bristles 43 do not remove the toner T attached to the surface of the photoconductor 31,
It is made of a material that can satisfactorily remove paper dust. For example, it is formed by dispersing carbon in rayon. Brush hair 43
Considering that the density of planting can also remove the paper dust satisfactorily.

The rotating brush 41 is arranged in parallel with the photosensitive member 31, the shaft 42 is rotatably supported by a member (not shown), and the tips of the brush bristles 43 are in contact with the surface of the photosensitive member 31.
The brush surface of the rotating brush 41 comes into contact with the surface of the photoconductor, and moves along with the movement of the surface of the photoconductor.
The basic action is to remove the paper dust adhering to the surface of 1. Therefore, the rotating brush 41 may be rotated by following the rotation of the photoconductor 31. Further, the rotating brush 41 may be rotated in the forward direction or the reverse direction with respect to the rotating direction of the photoconductor 31 by a rotation driving device (not shown). In this case, the shaft 42 is rotated by the rotary drive.
To rotate.

When the rotating brush 41 is rotated in the forward direction with respect to the rotating direction of the photoconductor 31, the peripheral speeds of both the rotating brush 41 and the photoconductor 31 may be the same, and the peripheral speed between them may be the same. You may make a difference. When a difference in peripheral speed is provided between the two, the rotation speed of the rotary brush 41 is set appropriately.
Even when the rotating brush 41 is rotated in the opposite direction with respect to the photoconductor 31, the rotation speed of the rotating brush 41 is appropriately set.
In practice, the rotary drive device rotates the rotary brush 41 in the opposite direction to the rotation direction of the photoconductor 31, or rotates the brush 41 in the forward direction with a peripheral speed difference. Reference numeral 44 denotes a case that receives the paper dust removed by the rotating brush 41.

The operation of the electrophotographic apparatus thus constructed will be described. The photosensitive member 31 is rotated in the direction of the arrow in the figure by the rotation drive mechanism. The following operation is performed by the rotation of the photosensitive drum 31. First, the surface of the photoconductor 31 is positively charged to a predetermined potential, for example, 500 V to 800 V, by corona discharge of the charging device 32 including scorotron charging.
It is charged to a potential of about V. Next, the exposure device 33 forms an electrostatic image on the surface of the photoconductor 31 according to the image information. The exposure device 33 performs exposure by blinking an LED according to image information. The latent image formed by this exposure is a negative latent image in which charges in the image area are removed.

Next, the developing device 34 forms a toner image on the surface of the photoconductor 31 in accordance with the electrostatic image. That is, the one-component toner T contained in the hopper 36 is supplied to the developing roller 37 by the rotating supply roller 38. The toner T is conveyed toward the photoconductor 31 by the rotating developing roller 37, contacts the blade 39 on the way and is charged, and is formed into a thin layer. The positively charged toner T is attached by the Coulomb force to a portion of the surface of the photoconductor 31 where the charge of the electrostatic latent image is removed by the developing roller 37 to form a toner image (reverse development).

In the developing device 34, the toner T remaining on the surface of the photoconductor 31 which has been fixed is sucked and collected by the developing roller 37 to perform a cleaning action. Then
In the transfer device 35, a recording sheet P (not shown) is conveyed while being sandwiched between the transfer roller 41 and the photoconductor 31 which are rotated by being applied with a voltage from the DC power source E3, and the toner image on the photoconductor 31 is transferred to the recording paper P. . In this transfer step, about 10 to 25% of the toner T adhering to the surface of the photoconductor 31 remains on the recording paper P without being transferred. At the same time, the paper dust S generated from the recording paper P adheres to the surface of the photoconductor 31. In particular, since the recording paper P is pressed against the surface of the photoconductor 31 by the transfer roller 40, a large amount of paper powder S adheres to the photoconductor 31. As shown in FIG. 3A, the toner T and the paper powder S existing on the surface of the photoconductor 31.
Is moved to the rotating brush 41 by the rotation of the photoconductor 31.

Next, the paper dust S on the photoconductor 31 is removed by the rotating brush 41 which is forcibly rotated in the direction of the arrow in the figure.
As shown in FIGS. 3B and 3C, in the rotary brush 41, the brush bristles 43 are rotated by the rotation of the shaft 42 and continuously slidably contact the surface of the photoconductor 31 to be attached to the surface of the photoconductor 31. The paper dust S present is peeled off from the surface of the photoconductor 31 and removed. In particular, talc contained in the paper dust S of the recording paper P is peeled off from the surface of the photoconductor 31 and removed. At this time, the toner T remaining and adhering to the surface of the photoconductor 31 is only disturbed by the rotating brush 41, and is not adhered and removed again after the disturbance. This is because the paper powder S is only attached to the photoconductor 31 due to an extremely weak electrostatic force.
This is because is firmly attached by Coulomb force. Also,
This is because the paper powder S, especially talc, has good slipperiness.

After the paper dust S has been removed by the rotating brush 41 in this manner, only the residual toner T moves to the charging step. The residual toner T is further charged to the positive electrode by the charging device 32, and is attracted to the developing roller 37 of the developing device 34 by a mirror image force in the developing process. Even if the paper dust S remains on the surface of the photoconductor 31 without being removed by the rotating brush 41, and the paper dust S enters the hopper 36 from the developing roller 37 and mixes with the toner T, the paper dust S and the toner T remain. In the triboelectric charging, the toner T is positively charged due to the charging series, and stable developing characteristics can be maintained.

As described above, according to the present invention, in the electrophotographic apparatus which employs the combination of the one-component contact reversal developing method, the residual toner collecting method by the developing apparatus and the contact transfer method, the rotating brush adheres to the surface of the photoreceptor after the transferring step. Since the paper dust of the recording paper is removed from the photoconductor, there is no stain called "fogging" where toner adheres to the non-image area, and the paper dust is clogged between the developing roller and the blade, causing streaks in the image. Therefore, the deterioration of the image due to the influence of the paper dust of the recording paper can be prevented, and a high-quality image can be stably secured for a long period of time.

Next, a second embodiment will be described with reference to FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. In this embodiment, the brush bristles 43 of the rotary brush 41 are made of a material having a characteristic ranging from conductive to medium resistance. For example, the brush bristles 43 are formed by dispersing carbon in rayon and have an electric resistance value of 10
It is formed with about ⁶ Ω · cm. A voltage is applied to the brush bristles 43 from the DC power source E4. Therefore, the rotating brush 41
The shaft 42 is formed of a conductive material and electrically connected to the DC power supply E3.

By doing so, the brush bristles 43 exert an electric suction force on the paper dust S adhering to the surface of the photoconductor 31 to strongly remove it from the surface of the photoconductor 31. Can be improved. The talc of the paper powder S is negatively charged due to the charging series, and by applying a positive voltage to the brush bristles 43, the removing effect is further enhanced. In this case, the brush bristles 43 and the photoconductor 31 need to be in contact with each other with a certain width. By applying the voltage of the rotating brush 41 in this manner, the paper dust of the photoconductor can be removed more firmly.

The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways. For example, the photoconductor is not limited to the drum. The recording medium is not limited to recording paper. Further, the brush is not limited to the rotating direction and may be, for example, a belt type.

[0035]

As described above, according to the electrophotographic apparatus of the present invention, the brush surface of the brush provided between the transfer device and the charging device is brought into contact with the surface of the photoconductor, so that the photoconductor can be used during photographic recording. By moving the brush surface of the brush as the surface moves, the paper dust of the recording paper adhering to the surface of the photoconductor after the transfer process can be removed from the photoconductor, and the one-component contact reversal development method and the residual by the developing device can be removed. With a combination of the toner recovery method and the contact transfer method, it is possible to prevent deterioration of the image due to the influence of the paper dust of the recording paper, and to stably secure a high-quality image for a long period of time. Then, by forming a brush having a characteristic ranging from conductive to medium resistance and applying a voltage, it is possible to more firmly remove the paper dust of the photoconductor.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an electrophotographic apparatus of a second embodiment.

FIG. 3 is an explanatory view showing the action of the brush.

FIG. 4 is a schematic configuration diagram showing a first conventional electrophotographic apparatus.

FIG. 5 is a schematic configuration diagram showing a second conventional electrophotographic apparatus.

FIG. 6 is a schematic configuration diagram showing a third conventional electrophotographic apparatus.

[Explanation of symbols]

31 ... Photosensitive member, 32 ... Charging device, 33 ... Exposure device, 34 ... Developing device, 35 ... Transfer device,
36 ... Hopper, 37 ... Developing device, 41 ... Rotating brush.

Claims (2)

[Claims] 1. An endless photosensitive member formed of a positively charged photoconductive member and rotated during image formation, a charging device for positively charging the surface of the photosensitive member, and a charging device for the charging device. An exposure device which is located on the downstream side in the rotation direction of the photoconductor and forms an electrostatic latent image on the surface of the photoconductor; and an exposure device which is located on the downstream side in the rotation direction of the photoconductor with respect to this exposure device and has the same polarity as the charging potential. And a developing device for contacting the surface of the photosensitive member with the developing roller carrying the toner to adhere the toner to the photosensitive member to visualize the electrostatic latent image to form a toner image. The toner image formed on the photoconductor is provided on the downstream side in the rotation direction of the photoconductor and includes a transfer roller that applies a voltage to contact the photoconductor and presses the recording paper from the back side to contact the photoconductor. It is equipped with a transfer device that transfers to recording paper. In the electrophotographic apparatus, in which the developing roller of the developing device collects the toner remaining on the surface of the photoconductor after passing through the transfer device to the developing device, the brush surface contacts the surface of the photoconductor. An electrophotographic apparatus is characterized in that a brush whose surface moves along with the movement of the surface of the photoconductor is provided between the transfer device and the charging device. 2. The electrophotographic apparatus according to claim 1, wherein the brush has a characteristic ranging from conductive to medium resistance, and a voltage is applied.