JPH08152832A - Electrophotographic device - Google Patents

Abstract

PURPOSE: To attract all remaining toner on an image carrier after transferring to a cleaning member with a simple constitution by providing a cleaning roller and a voltage impressing means. CONSTITUTION: A latent image is formed on the image carrier such as a photoreceptor 20 by performing charging and writing, toner is applied by a developing device 22, the latent image is visualized, and the visualized image on the image carrier is transferred to a paper P. In this case, the remaining toner on the image carrier after transfer is rubbed between the image carrier 20 and the cleaning roller 68 so as to be charged to the same polarity to be electrostatically attracted to the roller 68, on the other hand, a voltage is simulaneously impressed on the roller 68 by a voltage impressing means 75, and the remaining toner on the image carrier which is charged to the same polarity is attracted by the roller 68. Thus, all the remaining toner is attracted by electrostatic force to the roller 68, so that the surface of the image carrier is finely cleaned, even though both remaining toner having a positive polarity and that having a negative polarity coexist in the remaining toner on the image carrier after transfer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a laser copying machine, a laser printer or a laser facsimile which records on paper by an electrophotographic method. Specifically, a latent image is formed on an image bearing member such as a photoconductor by charging and writing, toner is attached by a developing device to make the latent image visible, and the latent image is visible on the image bearing member. The present invention relates to an electrophotographic apparatus that transfers an image onto paper.

[0002]

2. Description of the Related Art Conventionally, for example, in a laser copying machine,
As shown in FIG. 11, around the photosensitive drum 1, a developing unit 3, a transfer unit 4, a latent image forming unit 2 including a charging unit and an exposing unit, in a rotation direction of the photosensitive drum 1 indicated by an arrow in the drawing. There is one in which the transfer roller 5 is sequentially arranged, and a bias power source 7 is connected to the transfer roller 5 provided in contact with the photosensitive drum 1 through a changeover switch 6 (Japanese Patent Publication No. 61-3).
(See Japanese Patent Publication No. 0274).

At the time of recording, the surface of the photosensitive drum 1 is uniformly charged by the latent image forming section 2 and then a laser beam is irradiated to form an electrostatic latent image. Subsequently, the developing section 3 removes toner. The visible image is transferred onto the paper P that is attached and made visible, and is transferred at a timing in the transfer unit 4.

After the image transfer, for example, a bias voltage of + polarity is applied from the bias power source 7 to the transfer roller 5,
The transfer roller 5 electrostatically adsorbed the residual toner after the transfer on the photosensitive drum 1.

Then, when the collected toner adsorbed by the transfer roller 5 is reused, the changeover switch 6 is changed over to apply a bias voltage of negative polarity to the transfer roller 5, The collected toner adsorbed to the deposition roller 5 is attached to the surface of the photosensitive drum 1 until the next image is formed, and the collected toner attached to the surface of the photosensitive drum 1 is collected by the developing unit 3.

In addition, some conventional laser copying machines are shown in FIG.
As shown in FIG. 2, the charging unit 8 is provided around the photosensitive drum 1.
In the rotational direction of the photosensitive drum 1 shown by the arrow in the figure, the exposure unit 9, the developing unit 10 having four developing units, the intermediate transfer drum 11, and the rotating brush 13 are arranged and transferred to the outer periphery of the intermediate transfer drum 11. Equipped with a container 12 and a rotating brush 1
A bias power supply 15 is provided to the recovery roller 14 provided in contact with
There is also one in which (see Japanese Patent Laid-Open No. 5-61388).

At the time of recording, the surface of the photosensitive drum 1 is uniformly charged by the charging section 8, and the surface is irradiated with laser light from the exposure section 9 to form an electrostatic latent image. Part 10
One of the developing devices is developed to transfer the monochromatic toner image to the intermediate transfer drum 11, and in the case of multiple colors, this process is repeated to develop the toner images of the respective colors using the developing devices of the respective colors. The toner images on the intermediate transfer drum 11 are transferred onto the paper P sent at a timing by the transfer device 12 so as to form a multicolored color image by superposing and transferring them on the intermediate transfer drum 11.

By the way, in this type of copying machine, after the toner image on the photosensitive drum 1 is transferred onto the intermediate transfer drum 11, the residual toner on the photosensitive drum 1 after the transfer is rubbed by the rotary brush 13. , It is charged to the same polarity and adsorbed on the rotating brush 13, and at the same time, it is recovered by the bias power supply 15.
A bias voltage was applied to the roller 14 and the residual toner adsorbed on the rotating brush 13 was recovered by the recovery roller 14.

[0009]

However, most of the residual toner after transfer on the photosensitive member 1 has either + polarity or − polarity, but also has the opposite polarity. Therefore, among the conventional ones described above, FIG.
In the case shown in FIG. 1, the transfer roller 5 to which a voltage of one polarity is applied electrostatically adsorbs the residual toner, so that the residual toner of the other polarity cannot be adsorbed and all the residual toner cannot be adsorbed completely. There was a problem.

On the other hand, in the structure shown in FIG. 12, since the rotating brush 13 rubs the residual toner, the frictional force necessary for charging to the same polarity cannot be secured, and there is a problem that all the residual toner cannot be completely adsorbed. It was Further, since the recovery roller 14 is provided, there is another problem that the number of constituent parts increases and the cost increases.

Therefore, an object of the present invention is to completely adsorb all the residual toner after transfer on the image carrier to the cleaning member with a simple structure in the electrophotographic apparatus as described above.

[0012]

Therefore, according to the invention described in claim 1, a latent image is formed on an image bearing member such as the photoconductor 20 by charging and writing, for example, as shown in the following embodiments. Then, in the electrophotographic apparatus that attaches toner by the developing device 22 to visualize the latent image on the image carrier and transfers the visible image on the image carrier to the paper P, it is placed in contact with the image carrier. , A cleaning roller 68 which rotates to rub the residual toner after transfer on the image bearing member on the image bearing member, charges the toner with the same polarity, and sucks the cleaning roller 68, and the cleaning roller 68.
Voltage applying means 75 for applying a voltage to the cleaning roller 68 and applying a voltage to the cleaning roller 68 to apply a voltage to the cleaning roller 68.

According to the first aspect of the invention, during recording, the cleaning roller 68 is rotated together with the rotation of the image carrier, and the residual toner after transfer on the image carrier is rubbed between them, Are charged to the cleaning roller 68 by being charged to the same polarity, and at the same time, a voltage is applied to the cleaning roller 68 by the voltage applying means 75 to clean the residual toner on the image carrier charged to the same polarity. -La 68
And the surface of the image bearing member is cleaned.

According to a second aspect of the present invention, for example, as in the following illustrated embodiment, in the electrophotographic apparatus according to the first aspect, the recovered toner adsorbed by the cleaning roller 68 and recovered is reused. At this time, the voltage applying means 75
Then, a reverse voltage is applied to the cleaning roller 68, the collected toner adsorbed to the cleaning roller 68 is attached to the surface of the image carrier until the next image is formed, and the developing device 22 The voltage applying means 45 applies a voltage to the developing roller 43 of the developing device 22, and the collected toner adhering to the image carrier is adsorbed to the developing roller 43.

According to the second aspect of the invention, when the collected toner adsorbed by the cleaning roller 68 and reused is reused, the voltage application means 75 applies a reverse voltage to the cleaning roller 68. And cleaning roller 68
The collected toner adsorbed on the developing roller 43 adheres to the surface of the image carrier until the next image is formed, and a voltage is applied to the developing roller 43 to collect the collected toner on the developing roller 43. To the developing device 22.

According to a third aspect of the present invention, for example, as in the following illustrated embodiment, in the electrophotographic apparatus of the first aspect, the recovered toner adsorbed by the cleaning roller 68 and recovered is reused. At this time, the voltage application means 52 of the transfer device 23 applies a voltage to the transfer device 23 to charge the surface of the image carrier, and the cleaning roller 6 is charged.
The collected toner adsorbed on the recording medium 8 adheres to the surface of the image carrier until the next image is formed, and the developing device 22
Of the developing roller 4 of the developing device 22 by the voltage applying means 45 of
3 is applied, and the collected toner adhering to the image carrier is adsorbed to the developing roller 43.

In the third aspect of the invention, when the collected toner adsorbed by the cleaning roller 68 and collected is reused, the transfer device 23 charges the surface of the image carrier,
The collected toner adsorbed on the cleaning roller 68 is adsorbed on the surface of the image carrier until the next image is formed, and a voltage is applied to the developing roller 43 to collect the recovered toner adhered to the image carrier. It is adsorbed by the developing roller 43 and returned to the developing device 22.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, claim 1
1 shows an outline configuration of a main part of the laser copying machine in the embodiment of the invention described in FIG.

Reference numeral 20 in the drawing denotes a drum-shaped photoconductor 20. Around the photoconductor 20, a charging device 21, a developing device 22, a transfer device 23, and a cleaning device 24 are provided in a driving direction indicated by an arrow. The photoconductor 20, the charging device 21, the developing device 22, and the cleaning device 24 are integrated into a process cartridge D. Although not shown, an optical writing device is provided above the photoconductor 20.

First, the charging device 21 is constructed in detail as shown in FIG. Reference numeral 26 in the figure is a solenoid. A link 28 is provided on the actuating rod 27 of the solenoid 26.
One end. The other end of the link 28 is connected to one end of the arm 29. The other end of the arm 29 is bent at a right angle to form an L-shape in the lateral direction, and the other end is fixed to one end of the rotating shaft 30. The rotary shaft 30 is rotatably provided by supporting both ends between the side plates of the copying machine body. On the rotary shaft 30, a pair of frames 31 and 32 are fixed with a space,
They are provided facing each other. Opposed plate portion 31 of frame 31
Bearings 33 are provided slidably in the vertical direction in the figure on the opposing plate portion 32a of the frame a and the frame 32, respectively, and each is biased downward by a coil spring 34 in the figure. Then, the roller shaft 36 is supported by the bearings 33, and a conductive charging roller 35 is provided.

When the solenoid 26 is turned off, the urging member 38 pushes the actuating rod 27 upward in the drawing, and pushes up one end of the arm 29 via the link 28.
Rotate the rotating shaft 30 in the direction of arrow A in the drawing to charge the charging roller 35.
Is separated from the photoconductor 20. On the other hand, when the solenoid 26 is turned on, the actuation rod 27 is pulled downward in the figure against the biasing member 38, one end of the arm 29 is pulled through the link 28, and the rotary shaft 30 is rotated in the direction of arrow B in the figure. The charging roller 35 is pressed against the photoconductor 20 to move the coil spring 34.
And the charging roller 35 is pressed against the photoconductor 20 by the urging force.

As shown in FIG. 1, a voltage applying means 40 is connected to the charging roller 35 via a lead wire 37. The voltage applying means 40 is provided with a bias power supply 41, a changeover switch 42 and the like.

Next, the developing device 22 described above comprises a developing roller 43 provided therein and a voltage applying means 45 connected to the developing roller 43 via a lead wire 44. The voltage applying means 45 has a +
A bias power supply 46 for applying a polarity voltage, a bias power supply 47 for applying a negative voltage, a changeover switch 48, and the like are provided.

Further, the above-mentioned transfer device 23 is configured by connecting a voltage applying means 52 to a transfer roller 49 provided therein via a lead wire 51. The voltage applying means 52 includes a bias power source 53, a changeover switch 54 and the like. The transfer device 23 is also provided with a static elimination needle 50.

Finally, the above-mentioned cleaning device 24
Is configured as shown in FIG. 3 in detail. Reference numeral 5 in the figure
6 is a solenoid. Actuating rod 57 of solenoid 56
Is connected to one end of a link 58. The other end of the link 58 is connected to the base end of the clutch lever 59. The clutch lever 59 is provided so as to be rotatable around a fulcrum 60, and a claw portion 59a at the tip is provided so as to be engageable with a protrusion 61a of a clutch 61. The clutch 61 transmits and cuts off the driving force from the driving source, and includes two protrusions 61a on the outer circumference of the body.
It is attached to the cam shaft 62. The cam shaft 62 is rotatably provided with its both ends supported between the side plates of the laser copying machine body.
On the cam shaft 62, a pair of cams 63,
Fix 64.

A cleaning case 65 is provided in contact with the cams 63 and 64. The cleaning case 65 is
The photoconductor 20 has a horizontally long box shape in the axial direction.
A side wall 65b in the longitudinal direction is provided with a bearing 66 slidably in the left and right directions in the drawing, and a coil spring 67 biases the bearing 66 in the right direction in the drawing. Then, the roller shaft 69 is supported by the bearings 66, and the cleaning roller 68 is provided in the cleaning case 65. The cleaning roller 68 is made of a conductive elastic member such as conductive rubber and faces the window hole 65a. Then, the cleaning case 65 is attached to the spindle 7.
1, and the tension springs 72 are provided on both sides of the cleaning case 65 in the longitudinal direction.
Hang one end of. Each tension spring 72 has its other end hooked at an appropriate position, so that the cleaning case 65 is
Is pressed against the cams 63 and 64.

However, in the normal state in which the solenoid 56 is turned off, as shown in the figure, the urging member 73 urges the claw portion 59a of the clutch lever 59 to the projection 6 of the clutch 61.
It is engaged with 1a. At that time, the cleaning case 65 is pushed by the cams 63 and 64,
Is rotated counterclockwise about the support shaft 62 to press the cleaning roller 68 against the photoconductor 20, the coil spring 67 is bent, and the cleaning roller 68 is pressed with a pressing force of 3 g / cm or more. It is pressed against 20.

On the other hand, when the solenoid 56 is turned on, the operating rod 57 is pulled downward in the figure against the biasing member 73, the link 58 is pulled by the operating rod 57, and the clutch lever 59 is rotated clockwise around the fulcrum 60. It rotates to and the claw 59a is removed from the protrusion 61a. Then, the clutch 61 is engaged, the cam shaft 62 is rotated counterclockwise, and the cams 63 and 64 are rotated in the same direction.
Rotate. Then, following the rotation of the cams 63, 64, the tension spring 72 rotates the cleaning case 65 clockwise about the support shaft 71, and the cleaning roller 68 is rotated.
Is separated from the photoconductor 20.

Then, when the solenoid 56 is turned off,
The actuating rod 57 is pushed outside by the biasing member 74,
The link 58 is pushed up by 7 and the clutch lever 59 is rotated to engage the claw portion 59a with another protrusion (not shown). At that time, the cams 63 and 64 are rotated by approximately 180 degrees from the illustrated state. By such an operation, the cleaning roller 68 of the cleaning device 24 can be brought into contact with and separated from the photoconductor 20.

By the way, as shown in FIG. 1, the lead wire 7 is attached to the cleaning roller 68 of the cleaning device 24.
The voltage applying means 75 is connected via the circuit 4. The voltage applying means 75 includes a bias power supply 76 for applying a + polarity voltage, a bias power supply 77 for applying a −polarity voltage, a changeover switch 78, and the like.

When the print button is pressed when recording is performed using the illustrated laser copying machine, the charging roller 35 is pressed.
The cleaning roller 68 contacts the photoconductor 20. Then, as shown in FIG. 1, the photosensitive member 20 starts to rotate in the direction of the arrow, and at the same time, the charging roller 35, the developing roller 43, the transfer roller 49, and the cleaning roller are driven by a driving means (not shown). The la 68 and the transport roller 80 are rotationally driven in the directions indicated by the arrows. Further, when rotating the photoconductor 20, as shown in FIG. 4, the charging device 21, the developing device 22, the transfer device 2
3. The cleaning device 24 applies a bias voltage to each.

Then, after the surface of the photoconductor 20 is uniformly charged by the charging device 21, the surface of the photoconductor 20 is irradiated with a laser beam from an optical writing device to remove the electric charge in the image area and thereby the electrostatic latent image. Form an image. Subsequently, the developing device 22 attaches toner to the image portion to visualize the electrostatic latent image. Then, as shown in FIG. 5, this visible image is transferred by the transfer device 23 onto the upper surface of the sheet P conveyed to the lower side of the photoconductor 20.

After the transfer of the image, the charge of the sheet P is removed by the charge removal needle 50, and the transfer belt 83 conveys it to a fixing device (not shown) as shown in FIG. To discharge.

On the other hand, after the image transfer, the cleaning device 24 removes the residual toner on the photoconductor 20. That is, the cleaning rollers 68 rotate in the same rotation direction at the contact portion with the photoconductor 20 and at a speed 1.4 times as fast as the photoconductor 20, and between them, the cleaning roller 68 remains after the transfer on the photoconductor 20. Rub toner. At that time, as shown in FIG. 6, all the residual toner having a mixture of + polarity and − polarity is triboelectrically charged to − polarity. Then, the residual toner charged to the same polarity is sucked and collected by the cleaning roller 68 to which the bias voltage is applied.

As shown in FIG. 4, when the charging of the trailing edge of the image is completed, the charging device 21 stops applying the bias voltage. Then, the charging roller 35 separates from the photoconductor 20 by the above-described operation. When the transfer of the trailing edge of the image is completed, the transfer device 23 stops applying the bias voltage.

When the adsorption of the residual toner is completed, the changeover switch 78 is switched in the cleaning device 24 shown in FIG. 1, and the cleaning roller 68 has a voltage of the same polarity as the residual toner, that is, a negative polarity bias. Apply voltage. Then, the collected toner adsorbed on the cleaning roller 68 is applied to the photosensitive member 20 until the next image is formed.
It adheres to the surface and carries it to the developing device 22. At this time, the charge removal lamp 84 is turned on to set the potential of the photoconductor 20 to zero and weaken the adhesive force of the collected toner.

In the developing device 22, when the development of the trailing edge of the image is completed, the changeover switch 47 is switched to apply a voltage having a polarity opposite to that of the residual toner to the developing roller 43, that is, a positive polarity voltage. . Then, the collected toner adhering to the photoconductor 20 is adsorbed by the developing roller 43 and returned to the developing device 22. When the attraction to the developing roller 43 is completed, the voltage application to the developing roller 43 is stopped.

When images are continuously formed, as shown in FIG. 7, the bias voltage is repeatedly applied by the charging device 21, the developing device 22, the transfer device 23, and the cleaning device 24.

By the way, FIG. 8 is a graph showing the relationship between the applied voltage and the toner removal rate, with the vertical axis representing the toner removal rate on the photoconductor 20 and the horizontal axis representing the applied voltage. A in the figure
The line indicates an example of the residual toner charged in the negative polarity by frictional charging with the cleaning roller 68 shown in FIG.
The line shows an example of the residual toner charged to + polarity by frictional charging with the rotating brush shown in FIG.

As indicated by the line a in the figure, when the negative polarity bias voltage applied to the cleaning roller 68 is gradually increased, the toner removal rate sharply decreases and almost no residual toner can be removed. When a bias voltage of + polarity was applied, the toner removal rate immediately increased, and a good state could be maintained. From this, it can be seen that all of the residual toner between the photoconductor 20 and the cleaning roller 68 has a negative polarity.

On the other hand, as shown by the line b in the figure, when the negative polarity bias voltage applied to the collecting roller in FIG. 12 was gradually increased, the toner removal rate immediately increased, but not so much. Therefore, when the residual toner is rubbed by the rotating brush, the frictional force necessary for charging the toner to the same polarity cannot be secured, and the residual toner may not be aligned in the positive polarity between the photoconductor 20 and the cleaning roller 68. Recognize.

As is clear from the above, when the residual toner is rubbed by the cleaning roller 68, a sufficient frictional force required to charge the toner with the same polarity can be secured, and the toner removal rate can be increased as compared with the conventional case.

Next, in FIG. 9, the vertical axis represents the toner removal rate on the photoconductor 20 and the horizontal axis represents the relative speed ratio of the cleaning roller 68 to the photoconductor, and the relationship between the toner removal rate and the speed ratio. It is a graph which shows. In the figure, the horizontal axis 0 indicates that the cleaning roller 68 is stopped and only the photoconductor 20 is rotated. As can be seen from this figure, when the cleaning roller 68 is rotated in the same rotation direction as the photoconductor 20 at the contact portion between the photoconductor 20 and the cleaning roller 68, the rotation speed of the cleaning roller 68 becomes 1.4 times. , The toner removal rate does not increase. That is, unless the speed ratio is increased, the frictional force required to rub the residual toner and charge it to the same polarity cannot be secured. On the other hand, when the cleaning roller 68 is rotated in the opposite rotation direction to the photoconductor 20, the toner removal rate immediately increases. That is, it is possible to secure the frictional force necessary for rubbing the residual toner to be charged to the same polarity by reducing the speed ratio.

Therefore, in the illustrated embodiment, the cleaning roller 68 is rotated in the same rotation direction as the photoconductor 20 at the contact portion between the photoconductor 20 and the cleaning roller 68 to increase the toner removal rate. Although not shown, the cleaning roller 6 is rotated in the direction opposite to the rotation direction of the photoconductor 20 at the contact portion between the photoconductor 20 and the cleaning roller 68.
8 may be rotated to increase the toner removal rate.

By the way, in the illustrated embodiment described above,
When the collected toner adsorbed by the cleaning roller 68 is reused, a voltage in the opposite direction is applied to the cleaning roller 68 by the voltage application means 75, and the collected toner adsorbed on the cleaning roller 68 is removed. The developing device 22 adheres to the surface of the photoconductor 20 until the next image is formed.
Of the developing roller 4 of the developing device 22 by the voltage applying means 45 of
A voltage is applied to No. 3, and the collected toner adhering to the photoconductor 20 is adsorbed to the developing roller 43. However, although not shown in the drawing, when the collected toner adsorbed by the cleaning roller 68 is reused, a voltage is applied to the transfer device 23 by the voltage application means 52 of the transfer device 23 so that the surface of the photoconductor 20 is exposed. Of the collected toner adsorbed on the cleaning roller 68 until the next image is formed.
A structure in which the voltage is applied to the developing roller 43 of the developing device 22 by the voltage applying means 45 of the developing device 22 while adhering to the surface, and the collected toner adhering to the photoconductor 20 is adsorbed to the developing roller 43. May be

The conductive elastic member used for the cleaning roller 68 preferably has a hardness of 20 to 30 degrees in Asuka C. By doing so, the nip width between the photoconductor 20 and the cleaning roller 68 becomes smaller, so that the roller diameter can be made smaller and the size can be reduced.

The conductive elastic member used for the cleaning roller 68 has a volume resistance of 10 ³ Ω · cm to 10 ⁹
Ω · cm is recommended. By doing so, it is possible to prevent the residual toner charged to the negative polarity from being re-inverted to the positive polarity during cleaning.

Furthermore, the cleaning roller 68 made of a conductive elastic member can be made of a foamed molded product, and in this case, the bubble diameter on the surface is 50 μm or less, which is smaller than the bubble diameter inside thereof. Good. In this way, during cleaning, the residual toner can be adsorbed without entering the inside of the foam molding.

Furthermore, in the illustrated embodiment, an example in which the present invention is applied to a laser copying machine using a contact type charging device 21 that contacts the photoconductor 20 is shown. However, as shown in FIG. 10, it can be applied to a laser copying machine using a non-contact type charging device 21 such as a wire or a needle electrode.

Furthermore, in the illustrated embodiment, the photoconductor 20, the charging device 21, the developing device 22 and the cleaning device 24 are integrated to form a process cartridge D, and a laser copying machine equipped with such a process cartridge D. An example applied to However, as shown in FIG. 10, the photoconductor 20, the charging device 21, and the cleaning device 2
4 together to form the process cartridge E,
It can also be applied to a laser copying machine provided with such a process cartridge E.

Furthermore, in the illustrated embodiment, an example in which the invention is applied to a laser copying machine using the drum-shaped photoconductor 20 is shown. However, although not shown, the present invention can also be applied to a laser copying machine using a belt-shaped photoconductor.

Furthermore, in the illustrated embodiment, an example applied to a monochrome laser copying machine is shown. However, it may be applied to a color laser copying machine. In the color laser copying machine, for example, images formed on a photoconductor are sequentially transferred to an intermediate transfer belt to form a full color image on the transfer belt, and the full color image is transferred to paper to form an image. In such a color laser copying machine, an intermediate transfer member such as an intermediate transfer belt can be used as the image carrier.

[0053]

As described above, according to the first aspect of the present invention, the residual toner after transfer on the image carrier is rubbed between the image carrier and the cleaning roller and charged to the same polarity. Then, while electrostatically adsorbing to the cleaning roller, a voltage is simultaneously applied to the cleaning roller by the voltage applying means,
Since the residual toner on the image bearing member charged to the same polarity is adsorbed on the cleaning roller, even if the residual toner after transfer on the image bearing member contains both + and − polarities, it is easy. With the construction, all the residual toner can be completely adsorbed to the cleaning roller by electrostatic force to clean the surface of the image carrier.

According to the second aspect of the present invention, when the recovered toner adsorbed by the cleaning roller and recovered is reused, a voltage is applied in the opposite direction to the cleaning roller by the voltage applying means for cleaning. The collected toner adsorbed on the roller adheres to the surface of the image carrier until the next image is formed, and a voltage is applied to the developing roller to collect the recovered toner on the image carrier. Since the toner is adsorbed to the toner and returned to the developing device, it is possible to reliably reuse the collected toner without adding a complicated structure.

According to the third aspect of the invention, when the collected toner adsorbed and collected on the cleaning roller is reused, the surface of the image carrier is charged by the transfer device and adsorbed on the cleaning roller. The collected toner is adsorbed on the surface of the image carrier until the next image is formed, and a voltage is applied to the developing roller to adsorb the collected toner on the image carrier to the developing roller for development. Since the toner is returned to the apparatus, it is possible to reliably reuse the collected toner without adding a complicated structure.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a laser copying machine according to an embodiment of the invention described in claim 1.

FIG. 2 is a perspective view of a part of the charging device.

FIG. 3 is a perspective view of a part of a cleaning device provided in the laser copying machine.

FIG. 4 is a time chart showing voltage application during recording in the laser copying machine.

FIG. 5 is an explanatory diagram illustrating a charged state of toner during recording.

FIG. 6 is an explanatory diagram illustrating that residual toner after image transfer has the same polarity between the photoconductor and the cleaning roller.

FIG. 7 is a time chart showing voltage application during continuous recording in a laser copying machine.

FIG. 8 is a graph showing the relationship between the applied voltage and the toner removal rate, with the vertical axis representing the toner removal rate on the photoconductor and the horizontal axis representing the applied voltage.

FIG. 9 is a graph showing the relationship between the speed ratio and the toner removal rate, with the vertical axis representing the toner removal rate on the photosensitive body and the horizontal axis representing the relative speed ratio of the cleaning roller to the photoconductor.

FIG. 10 is a schematic configuration diagram of a main part of a laser copying machine including different charging devices.

FIG. 11 is a schematic configuration diagram of a main part of a conventional laser copying machine.

FIG. 12 is a schematic configuration diagram of a main part of another conventional laser copying machine.

[Explanation of symbols]

 20 Photoreceptor 22 Developing Device 23 Transfer Device 43 Developing Roller 45 Voltage Applying Means 52 Voltage Applying Means 68 Cleaning Roller 75 Voltage Applying Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masako Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Company (72) Naofumi Shoji 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor So Kai Kai 3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Osamu Endo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company ( 72) Inventor Yoshiko Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Innovator Nobuto Yokokawa 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Yukiko Iwasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A latent image is formed on an image bearing member by charging and writing, toner is attached by a developing device to visualize the latent image, and the visible image on the image bearing member is printed on a sheet. In the electrophotographic apparatus for transferring to the image carrier, the image carrier is placed in contact with the image carrier, and the toner remaining on the image carrier after transfer is rubbed between the image carrier and charged to the same polarity. And a voltage applying means for applying a voltage to the cleaning roller to attract residual toner on the image bearing member charged to the same polarity to the cleaning roller. An electrophotographic device. 2. When reusing the collected toner adsorbed and collected on the cleaning roller, a voltage in the opposite direction is applied to the cleaning roller by the voltage applying means and the collected toner is adsorbed on the cleaning roller. The collected toner is adhered to the surface of the image carrier until the next image is formed, and the voltage applying means of the developing device causes the developing roller of the developing device to develop.
2. The electrophotographic apparatus according to claim 1, wherein a voltage is applied to the toner, and the collected toner adhering to the image carrier is adsorbed to the developing roller. 3. When the collected toner adsorbed by the cleaning roller and collected is reused, a voltage is applied to the transfer device by the voltage application means of the transfer device to charge the surface of the image carrier. The collected toner adsorbed to the cleaning roller adheres to the surface of the image carrier until the next image is formed, and the developing roller of the developing device is driven by the voltage applying means of the developing device.
2. The electrophotographic apparatus according to claim 1, wherein a voltage is applied to the toner, and the collected toner adhering to the image carrier is adsorbed to the developing roller.