JPH11258958A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of easily removing/ recovering residual toner efficiently by charging the residual toner on an electrostatic latent image carrying rotary body such as a photoreceptor while suppressing generation of ozone, as for the image forming device of electrostatic photographic system. SOLUTION: This image forming device is provided with a static charge charger 411, an exposing device 42, a developing device 43, a transfer charger 44, a separation charger 45, a cleaning device 46, and an optical eraser 47 are arranged on respective position opposite to a photoreceptor 8. Then, the device is allowed to arrange an electric charge imparting device D1 provided with a power source PS1 capable of impressing a voltage on a charging sheet and an electrode layer of a charging sheet S1 held in contact with the photoreceptor 8, downstream the transfer charger 44 and the separation charger 45 in the rotary direction of the photoreceptor 8, and upstream the cleaning device 46. The device is allowed to eliminate the static charge from the toner before cleaning by impressing the voltage of the electrode layer on the charging sheet S1, and letting the discharge to be performed from the electrode layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus for forming a toner image on a recording sheet by an electrophotographic image forming process.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a toner image is formed on a recording sheet in the following manner, for example. First, an electrostatic latent image is formed on a photoconductor.
Thereafter, the electrostatic latent image is visualized by a developing device using toner charged to either positive or negative polarity. As a result, a toner image is formed on the photoconductor. The toner image on the photoreceptor is directly transferred to a recording sheet such as paper, or a color image capable of forming a toner image of a plurality of colors (for example, four colors of yellow, magenta, cyan, and black) on the recording sheet. In a forming apparatus or the like, the toner image may be once transferred to an intermediate transfer body such as an intermediate transfer belt and then transferred to a recording sheet. The toner image transferred to the recording sheet is fixed thereafter.

Most of the toner image on the photosensitive member is transferred to a transfer target such as a recording sheet or an intermediate transfer member, but may not be transferred and may partially remain on the photosensitive member. Usually, the residual toner is removed by a cleaning device so that the residual toner does not adversely affect the next image formation.
Collected. The cleaning device removes the toner from the photoconductor by, for example, scraping off the toner on the photoconductor by a cleaning blade that contacts the photoconductor.

When a part or all of the toner image formed on the photosensitive member is not transferred to the recording sheet or the intermediate transfer member due to an abnormality such as a paper jam (jam), the toner image is not transferred onto the photosensitive member. Toner remains. Such toner is also removed by the cleaning device. Also, in order to determine development conditions such as a development bias voltage,
When forming an AIDC toner pattern on a photoreceptor,
Since the IDC toner pattern is not normally transferred to the recording sheet, all of the IDC toner pattern remains on the photoconductor. A toner image that is not transferred to a recording sheet or the like like the AIDC toner pattern is also removed by the cleaning device.

In any case, in order to facilitate the removal of the toner by the cleaning device, it has been proposed to remove the charge from the toner using a corona charger before removing the toner. When the charge is removed from the toner, the electrostatic attraction of the toner to the photoconductor is weakened, and the toner can be easily and efficiently removed from the photoconductor.

[0006]

However, when electricity is removed from the toner on the photoreceptor by the corona charger, ozone is generated to cause deterioration of the photoreceptor and devices disposed near the photoreceptor. Accordingly, the present invention provides an electrophotographic image forming apparatus in which toner remaining on a rotating body carrying an electrostatic latent image such as a photoreceptor is charged with less generation of ozone, and the remaining toner is easily and efficiently removed. It is an object to provide an image forming apparatus that can be collected.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an image forming apparatus for forming an image by an electrophotographic image forming process, comprising: a rotating member carrying an electrostatic latent image; A charging device capable of charging the peripheral surface of the rotating body carrying the electrostatic latent image, and an electrostatic device capable of forming an electrostatic latent image on the peripheral surface of the rotating body carrying the electrostatic latent image charged by the charging device A latent image forming apparatus, a developing apparatus capable of developing an electrostatic latent image formed by the electrostatic latent image forming apparatus on the peripheral surface of the rotating body carrying the electrostatic latent image using toner, and the developing apparatus A transfer device capable of transferring a toner image formed on the rotating body of the electrostatic latent image carrying member to a transfer receiving body, and charging the toner on the peripheral surface of the rotating body of the electrostatic latent image carrying body, The transfer device moves the electrostatic latent image bearing rotating body in the rotation direction. A charging sheet for partially contacting the peripheral surface of the rotating body with the electrostatic latent image on the downstream side and upstream of the charging device, comprising: an electrode layer; Including an insulating layer provided at the upstream end in the rotation direction of the electrostatic latent image bearing rotating body,
An image forming apparatus comprising: a charged sheet for bringing at least a part of the downstream side of the upstream end into contact with the rotating body for carrying an electrostatic latent image; and a power supply capable of applying a voltage to the electrode layer. I will provide a.

The image forming apparatus of the present invention is for forming a toner image on a recording sheet such as paper, an OHP sheet, cloth, or the like by an electrophotographic image forming process. The image forming apparatus of the present invention can be used, for example, as a copier, a printer, a facsimile machine, a multifunction machine thereof, and the like. The image forming apparatus includes an electrostatic latent image bearing rotating body, a charging device, an electrostatic latent image forming device, a developing device, and a transfer device in order to form a toner image on a recording sheet in an electrophotographic image forming process. Have. The charging device, the developing device, and the transfer device are arranged in this order at positions facing the peripheral surface of the rotating body carrying the electrostatic latent image. The electrostatic latent image forming device is arranged so that an electrostatic latent image can be formed between the charging device and the developing device. Examples of the shape of the rotating body carrying the electrostatic latent image include a drum shape, a roller shape, and an endless belt shape. As the electrostatic latent image bearing rotating body, for example, a photoconductor can be mentioned. In the case of a photoconductor, the electrostatic latent image forming device is an image exposing device.

The image forming apparatus forms a toner image on a recording sheet as follows. First, the peripheral surface of the rotating body carrying the electrostatic latent image is charged by the charging device. An electrostatic latent image corresponding to a toner image finally formed by the electrostatic latent image forming apparatus is formed on the charged electrostatic latent image bearing rotating body peripheral surface. The electrostatic latent image is developed by a developing device using a toner charged to either positive or negative polarity and visualized. As a result, a toner image is formed on the peripheral surface of the rotating body carrying the electrostatic latent image, and the toner image is transferred to the transfer target by the transfer device. Furthermore,
The toner image is directly transferred to a recording sheet by a transfer device to form a toner image on the recording sheet. Alternatively, the toner image is temporarily transferred to an intermediate transfer member by a transfer device, and then the toner image on the intermediate transfer member is secondarily transferred to a recording sheet to form a toner image on the recording sheet.

The image forming apparatus can apply a voltage to a charged sheet and an electrode layer of the charged sheet to be brought into contact with the electrostatic latent image bearing rotating body in order to charge the toner on the electrostatic latent image bearing rotating body. It has a power supply. By applying a voltage to the electrode layer of the charging sheet, discharge can be performed from the electrode layer, thereby charging the toner on the rotating body carrying the electrostatic latent image. Therefore, it is possible to remove the charge from the charged toner on the rotating body carrying the electrostatic latent image, or to charge the toner to a desired polarity.

The charged sheet is brought into contact with the peripheral surface of the rotating body carrying the electrostatic latent image on the downstream side in the rotation direction of the rotating body carrying the electrostatic latent image from the transfer device and upstream of the charging device. This makes it possible to remove the charge from the toner remaining on the rotation of the electrostatic latent image carrying member without being transferred to the recording sheet or the intermediate transfer member by the charged sheet or to charge the toner to a desired polarity. Further, the toner remaining on the electrostatic latent image bearing rotating body without being transferred to the recording sheet or the intermediate transfer body for some reason such as a trouble can be charged for static elimination or the like. Furthermore, even when formed on a rotating body carrying an electrostatic latent image, such as an AIDC toner pattern formed for determining development conditions, toner that is not transferred to a recording sheet or the like can be charged for charge elimination and the like. Since the charged sheet charges the toner on the rotating body carrying the electrostatic latent image, the discharge distance can be shortened as compared with a conventional corona charger, as described later, and the generation of ozone can be suppressed accordingly. Thereby, the rotating body carrying the electrostatic latent image,
It is possible to suppress deterioration of the charged sheet, devices and components disposed near the charged sheet, deterioration of the members, and diffusion and release of ozone outside the image forming apparatus.

The toner remaining on the rotating member carrying the electrostatic latent image may be removed and collected so as not to adversely affect the next image formation. The toner on the rotating body carrying the electrostatic latent image may be collected by a developing device. When the toner is collected by the developing device, for example, the toner is charged so that the toner does not easily adhere to the charging device that passes on the way to the developing device, and can be smoothly removed and collected in the developing device. be able to.

Alternatively, a cleaning device is disposed downstream of the transfer device in the rotational direction of the electrostatic latent image bearing rotary member and facing the electrostatic latent image bearing rotary member upstream of the charging device. The toner may be collected by the device. By providing the cleaning device with, for example, a cleaning blade or a cleaning brush that comes into contact with the electrostatic latent image bearing rotating body, toner can be collected. In the case where the cleaning device is provided at the above-described position, the charged sheet is brought into contact with the peripheral surface of the electrostatic latent image bearing rotator downstream of the transfer device in the rotation direction of the electrostatic latent image bearing rotator and upstream of the cleaning device. I just need. When such a cleaning device is employed, it is preferable to remove the charge from the toner using a charged sheet, for example. As a result, the electrostatic attraction force of the toner on the rotating member carrying the electrostatic latent image can be reduced, and the toner can be easily and efficiently removed and collected.

The charging of the toner on the rotating member carrying the electrostatic latent image is performed by applying a voltage to the electrode layer of the charged sheet and discharging the electrode layer as described above. The electrode layer of the charging sheet is connected to a power supply. Examples of the power supply include a power supply to which a DC voltage can be applied, a power supply to which an alternating voltage (oscillation voltage) can be applied, and a power supply to which an alternating voltage can be superimposed and applied to the DC voltage. . Examples of the alternating voltage include a pulse voltage, a sine wave voltage, and a triangular wave voltage. In any case, the power supply may be a variable output voltage power supply.

The voltage applied to the electrode layer of the charged sheet may be changed in accordance with, for example, the following conditions or in accordance with the change in the conditions. The applied voltage may be changed in proportion to the change in the condition. The applied voltage is
It may be changed stepwise (stepwise) with respect to the change of the condition. In any case, if the absolute value of the applied voltage is increased, the amount of charge on the toner on the rotating member carrying the electrostatic latent image can be increased. A voltage according to the environmental temperature may be applied to the electrode layer.

When the toner is removed by the cleaning blade as described above, when the temperature is low, the resilience of the cleaning blade is reduced and the cleaning performance is reduced. May be increased. Thereby, for example, the charge removal amount may be increased. A voltage according to the environmental humidity may be applied to the electrode layer.

When the environmental humidity is high, the transfer efficiency of the toner image to a recording sheet or the like is reduced, and the amount of toner remaining on the rotating member carrying the electrostatic latent image is increased. May be increased. A voltage corresponding to the number of times of image formation may be applied to the electrode layer. When the toner is removed by the cleaning blade as described above, when the number of image formations increases, the cleaning blade wears and the cleaning performance deteriorates. May be increased. Thereby, for example, the charge removal amount may be increased. The voltage applied to the electrode layer may be changed depending on whether or not the toner image formed on the rotating body carrying the electrostatic latent image has been transferred to the body to be transferred.

During the image forming process, a part or all of the toner image formed on the rotating member carrying the electrostatic latent image is transferred to the recording sheet or the intermediate transfer member due to an abnormality such as a jam of the recording sheet. If not, the amount of toner remaining on the rotating body carrying the electrostatic latent image becomes larger than when a normal image is formed and the toner image is transferred to a recording sheet or the like. Therefore, when the transfer of the toner image is not performed, the absolute value of the voltage applied to the electrode layer may be larger than when the transfer is performed.

Further, the AID is placed on the rotating body carrying the electrostatic latent image.
When the C toner pattern is formed, the AIDC toner pattern is not transferred onto a recording sheet or the like, so that the amount of toner on the rotating body carrying the electrostatic latent image increases. So AIDC
When a toner image that is not transferred to a recording sheet or the like like a toner pattern is formed on a rotating body carrying an electrostatic latent image, the absolute value of the voltage applied to the electrode layer may be increased.

The voltage applied to the electrode layer may be changed by combining two or more of the conditions described above.
As described above, when changing the voltage applied to the electrode layer of the charging sheet according to the change in the condition, the power supply connected to the electrode layer is set to a variable output voltage power supply, and the output voltage of the power supply is changed according to the change in the condition. What is necessary is just to provide the control part etc. which can be changed. Condition information is input to the control unit. In order to input the condition information, a sensor or the like for detecting condition information such as humidity may be provided in the image forming apparatus as needed.

Hereinafter, the charged sheet will be further described. In the following description, the "rotation direction of the electrostatic latent image bearing rotator" may be simply referred to as the "rotation direction".
“Upstream in the rotation direction of the electrostatic latent image bearing rotating body” may be simply referred to as “upstream”. The “downstream side in the rotation direction of the electrostatic latent image bearing rotating body” may be simply referred to as “downstream side”.

The charged sheet is a sheet having a larger area than the thickness. The charged sheet may be a flexible sheet having self-retention and elasticity, or a thin sheet (film) having less self-retention and less elasticity. A part (typically, a part of the surface) of the charged sheet is brought into contact with the rotating body carrying the electrostatic latent image. The upstream end of the charged sheet is supported. The upstream end of the charged sheet is supported at a predetermined distance from the electrostatic latent image bearing rotating body. A part (typically, part of the surface) downstream of the supported upstream end of the charged sheet is brought into contact with the rotating member carrying the electrostatic latent image.

The thickness of the charged sheet is several tens μm to several tens.
It is preferably about 0 μm. If the thickness of the charged sheet is too large, the adhesion to the electrostatic latent image bearing rotating body is deteriorated, and the charged sheet cannot be brought into contact with the shape of the electrostatic latent image bearing rotating body. If the thickness of the charged sheet is too small, the strength becomes weak. The charged sheet is a sheet having a laminated structure of two or more layers including an electrode layer and an insulating layer provided on the side of the electrode layer on which the latent electrostatic image bearing member is rotated. At least one layer of an insulating layer is arranged between the electrode layer and the rotating body carrying the electrostatic latent image. The charged sheet may have a laminated structure of three or more layers by further providing another layer on the side of the electrostatic latent image bearing rotating body of the insulating layer. The charged sheet may have a laminated structure of three or more layers by providing another layer on the opposite side of the electrode layer from the rotating body carrying the electrostatic latent image.

The electrode layer may be made of a conductive material, or may be made of an electric resistance material (semi-conductive material). Such conductive materials include, for example, chromium, copper,
Examples include metals such as gold, platinum, tungsten, indium, and titanium, ITO, and carbon. As such a resistance material, for example, tetrafluoroethylene resin, ethylene-tetrafluoroethylene copolymer (PETF)
E), a conductive material such as carbon dispersed in a fluororesin such as polyvinylidene fluoride (PVdF), or a conductive material dispersed in a synthetic resin such as polyimide, polyester, polyether, polyamide, polyolefin, or polycarbonate. And conductive rubber dispersed in synthetic rubber such as urethane rubber.
When the electrode layer is made of, for example, a resistance material, its volume resistance is 10 Ω · cm or more (preferably 1 Ω · cm).
0 ³ Ω · cm or more), it is possible to stably discharge from the electrode layer even in a high-humidity environment and to suppress abnormal dot discharge from the electrode layer. in this case,
The volume resistance of the resistive material should be 10 ⁸ so that the voltage applied to the electrode layer for discharging from the electrode layer does not increase significantly.
It is preferably set to Ω · cm or less (preferably, 10 ⁷ Ω · cm or less). In the electrode layer, only the portion including the discharge point may be formed of a resistive material, and the other portions may be formed of a conductive material. Also in this case, it is possible to stably discharge from the electrode layer in a high humidity environment and to suppress abnormal dot discharge from the electrode layer.

Since a part of the charged sheet is brought into contact with the rotating member carrying the electrostatic latent image, the downstream end of the electrode layer can be arranged close to the rotating member carrying the electrostatic latent image without coming into contact with the rotating member. The electrode layer can be separated from the electrostatic latent image bearing rotating body by at least the thickness of the insulating layer. Therefore, the discharge distance can be shortened accordingly, and generation of ozone can be suppressed. When the shortest distance between the electrode layer and the rotating body carrying the electrostatic latent image is set to 11 μm or more according to the Paschen's rule, good discharge can be performed from the electrode layer. Thus, abnormal discharge and uneven charging of the toner on the rotating body carrying the electrostatic latent image due to the abnormal discharge can be suppressed. The shortest distance between the electrode layer and the rotating body carrying the electrostatic latent image is preferably 100 μm or less in order to shorten the discharge distance and suppress the generation of ozone. Therefore, the shortest distance between the electrostatic latent image bearing rotating body and the electrode layer is 11
It is preferable that it is from μm to 100 μm. The shortest distance can be adjusted by the thickness of an insulating layer provided on the side of the electrostatic latent image bearing rotating body with respect to the electrode layer.

In order to suppress discharge from the electrode layer to devices and members other than the electrostatic latent image bearing rotating body disposed near the charged sheet, the electrode layer is located on the side opposite to the electrostatic latent image bearing rotating body. May be covered with a second insulating layer. Further, in order to prevent discharge from a side end of the electrode layer in a direction crossing the rotation direction of the electrostatic latent image holding rotator (a rotation axis direction of the electrostatic latent image holding rotator), a side end of the charged sheet is prevented. May not be provided with an electrode layer.

When a voltage is applied to the electrode layer of the charged sheet,
The portion of the charged sheet downstream from the supported upstream end is electrostatically attracted in the direction of the electrostatic latent image bearing rotating body. Further, the downstream portion of the charged sheet is pulled to the downstream side by the rotation of the rotating member carrying the electrostatic latent image. As a result, the downstream portion of the charged sheet comes into contact with the electrostatic latent image bearing rotator while being bent or deformed according to the shape of the electrostatic latent image bearing rotator. Therefore, even if the rotating surface of the rotating electrostatic latent image bearing member undulates or vibrates, the downstream portion of the charged sheet is statically bent or deformed in accordance with the undulation or the like. The contact state with the rotating body carrying the latent image can be maintained. Thereby, the distance between the electrode layer of the charged sheet and the rotating body carrying the electrostatic latent image is stabilized, and the discharge from the electrode layer can be performed stably.

The charged sheet may be described in the following (A), (B) and (C). (A) The downstream end of the electrode layer may have a shape in which irregularities are arranged in a direction transverse to the rotation direction of the rotating body for carrying the electrostatic latent image (the direction of the rotation axis of the rotating body carrying the electrostatic latent image). The unevenness is formed by the length of each part of the electrode layer in the rotation direction.

In this case, the projection at the downstream end of the electrode layer of the charged sheet is the discharge point. When the downstream end has such a shape in which the unevenness is lined up, compared to the case where the downstream end of the electrode layer is linear, adhesion of foreign matter such as paper dust and toner, unevenness of the electrode layer surface state, and environmental change The discharge point is also stabilized by such factors, so that uniform and stable discharge can be performed from the electrode layer. If the pitch of the protrusions in the direction of the rotation axis of the electrostatic latent image bearing rotating body is too large, uneven charging (uneven potential) of the toner on the electrostatic latent image bearing rotating body occurs. At the downstream end face is linear. Therefore, it is preferable that the pitch of the projections is about several tens μm to several hundreds μm. Examples of the concavo-convex shape include a comb shape and a saw-tooth shape. (B) The downstream end of the electrode layer may be made to protrude more downstream than another layer provided on the side of the electrostatic latent image bearing rotating body from the electrode layer of the charged sheet. The other layer includes the insulating layer. When another layer is provided on the side of the electrostatic latent image bearing rotating body relative to the insulating layer, the electrode layer is made to protrude further downstream than the downstream end of the insulating layer and the other layer.

In this case, the discharge is mainly performed from the surface of the protruding end of the electrode layer protruding downstream of the insulating layer, facing the rotating body carrying the electrostatic latent image. In this case, discharge from the electrode layer is facilitated, and uniform and stable discharge can be performed accordingly. In order to cause stable discharge from the electrode layer, the amount of protrusion L [mm] of the electrode layer to the downstream side is set so that the proximity discharge time T becomes 0.002 to 0.3 [sec]. Preferably, 0.005 to 0.1 [s
ec] is more preferably set. The proximity discharge time T [sec] is a value obtained by dividing the amount of protrusion L by the peripheral surface moving speed V (= L / V), where V is the peripheral surface moving speed of the electrostatic latent image bearing rotating body. ).

The end of the electrode layer protruding downstream from the insulating layer may be warped so that the distance between the end and the rotating body carrying the electrostatic latent image increases as it goes downstream. By doing so, abnormal discharge from the downstream end (the downstream end surface or the edge portion at the downstream end) of the protruding end of the electrode layer can be suppressed, and the surface discharge from the protruding end can be stabilized accordingly. Can be done.

The downstream end face of the protruding end of the electrode layer may be covered with an insulator. Also in this case, the abnormal discharge from the downstream end of the protruding end of the electrode layer can be suppressed, and the surface discharge from the protruding end can be stably performed accordingly. Examples of such an insulator material include a fluorine resin such as tetrafluoroethylene resin, a synthetic resin such as polyimide, polyester, and polyether, and a synthetic rubber such as urethane rubber.

In order to prevent the protruding end of the electrode layer from bending and deforming in the direction of the electrostatic latent image bearing rotating body, the electrode layer is reinforced on the side opposite to the surface facing the electrostatic latent image bearing rotating body. A layer may be provided. When the protruding end of the electrode layer is prevented from bending and deforming in the direction of the electrostatic latent image bearing rotating body, the distance between the projecting end having a discharge surface and the electrostatic latent image bearing rotating body can be kept constant. In other words, in other words, the discharge distance can be kept constant, and accordingly, a stable discharge can be performed from the electrode layer. Instead of or along with providing such a reinforcing layer, the thickness of the electrode layer itself may be increased. Also,
The second insulating layer provided on the surface of the electrode layer on the opposite side to the rotating member carrying the electrostatic latent image may have the function of the reinforcing layer. (C) The electrode layer may be divided into two or more in a direction transverse to the rotation direction of the rotating body for carrying the electrostatic latent image (the direction of the rotation axis of the rotating body carrying the electrostatic latent image). In this case, a voltage may be independently applied to each of the divided electrode layer portions. When the electrode layer is divided into three or more in the direction of the rotation axis, the divided electrode layer portions may be divided into two or more groups so that a voltage can be independently applied to each group.

When a plurality of types of toner images having different widths in the direction of the rotation axis are formed on the rotating body carrying the electrostatic latent image, the electrode layer is divided into two or more in accordance with the width of each toner image in the direction of the rotation axis. May be. This way,
It is possible to discharge only from the electrode layer portion facing only the peripheral surface region where the toner image is formed, in other words, the peripheral surface region where the toner may remain, in the peripheral surface region of the electrostatic latent image bearing rotating body. it can. When the AIDC toner pattern described above is formed on a rotating body carrying an electrostatic latent image, the AID
The electrode layer may be divided into two or more in the rotation axis direction so that only the toner of the C toner pattern can be charged.

The above description in (A), (B) and (C) may be a combination of two or more. Specific structural examples of the charged sheet are shown in the following (1) to (3). (1) The charging sheet is a sheet having a laminated structure of two or more layers including the electrode layer and the insulating layer provided on the side of the electrode layer on which the electrostatic latent image is held by the rotating body. It may be brought into contact with the image bearing rotating body. For example, the charged sheet may be a sheet having a two-layer structure in which an electrode layer and an insulating layer provided on the side of the electrode layer on which the electrostatic latent image is held are rotated.

In this case, the discharge distance can be adjusted by adjusting the thickness of the insulating layer. The charged sheet may be formed by separately forming the electrode layer and the insulating layer and then overlapping them. When the electrode layer is made of a resistance material as described above,
These electrode layer and insulating layer may be integrally formed of a resistance gradient composite material. When the electrode layer is made of a resistive material, the resistive material may be applied on the insulating layer to form the electrode layer. When the electrode layer is made of a conductive material such as a metal as described above, the electrode layer may be formed on the insulating layer by using a film forming technique such as sputtering. Further, an electrode layer having a predetermined pattern may be formed on the insulating layer by using both a film forming technique such as sputtering and an etching technique such as photoetching. The charged sheet described in (2) and (3) described later can be formed in the same manner as described above.

By providing an insulating layer on the side of the charged sheet that comes into contact with the rotating member carrying the electrostatic latent image, it is possible to prevent the electrode layer from being damaged and to perform stable discharge from the electrode layer for a long period of time. Can be. It is preferable that the insulating layer of the charged sheet that comes into sliding contact with the rotating body carrying the electrostatic latent image is made of a material having excellent slidability and wear resistance. Examples of such an insulating layer material include fluorine resin such as tetrafluoroethylene resin, synthetic resin such as polyimide, polyester, and polyether, and synthetic rubber such as urethane rubber and silicon rubber. The insulating layer may be formed of a material having good releasability from the toner.

As described above, the downstream end of the electrode layer may have a shape in which irregularities are arranged in the direction of the rotation axis of the rotating body carrying the electrostatic latent image. As described above, the electrode layer may protrude downstream from the insulating layer of the charged sheet. As described above, the electrode layer may be divided into two or more in the direction transverse to the rotation direction of the rotating body carrying the electrostatic latent image. (2) The charging sheet includes the electrode layer (hereinafter, referred to as “first electrode layer”), the insulating layer provided on the electrostatic latent image bearing rotating body side of the first electrode layer, and an electrostatic latent image of the insulating layer. As a sheet having a laminated structure of three or more layers including the second electrode layer provided on the supporting rotating body side, a part of the second electrode layer may be brought into contact with the electrostatic latent image carrying rotating body. For example, the charged sheet is the first
The sheet may have a three-layer structure in which an electrode layer, an insulating layer provided on the electrostatic latent image bearing rotator side of the first electrode layer, and a second electrode layer provided on the insulating layer on the electrostatic latent image bearing rotator side are laminated. .

In this case, the discharge distance of the first electrode layer can be adjusted by adjusting the thickness of the insulating layer and the second electrode layer. The second electrode layer is also connected to a power supply capable of applying a voltage to the second electrode layer, like the first electrode layer. The second electrode layer is also similar to the first electrode layer,
It may be made of a conductive material or may be made of an electric resistance material. As a power supply capable of applying a voltage to the second electrode layer, similarly to a power supply capable of applying a voltage to the first electrode layer, for example, a power supply capable of applying a DC voltage and an alternating voltage (oscillation voltage), and an alternating voltage superimposed on the DC voltage And a power source that can be applied. The power supply may be a variable output voltage power supply. Similarly to the voltage applied to the first electrode layer, the voltage applied to the second electrode layer may be changed according to conditions such as environmental temperature and environmental humidity.

As described above, when the charged sheet has a laminated structure of three or more layers including the first electrode layer, the insulating layer, and the second electrode layer that is brought into contact with the rotating member carrying the electrostatic latent image, the charged sheet is formed by the above-described electrode. Distance between the second electrode layer generating electrostatic attraction and the electrostatic latent image bearing rotator as compared with the case of a two or more layered structure including a layer and an insulating layer contacting the electrostatic latent image bearing rotator , The electrostatic attraction of the charged sheet to the rotating member carrying the electrostatic latent image can be increased.

As described above, when the charged sheet has a laminated structure of three or more layers including the first electrode layer, the insulating layer and the second electrode layer which is brought into contact with the rotating body carrying the electrostatic latent image, the first and second electrodes are used. Discharge may be performed from any of the layers. Alternatively, the charged sheet is discharged only from the first electrode layer that is not brought into contact with the rotating member carrying the electrostatic latent image, and is discharged from the second electrode layer that is brought into contact with the rotating member carrying the electrostatic latent image. It may be used only for electrostatic attraction in the direction of the electrostatic latent image bearing rotating body.

The discharge from the first electrode layer is mainly generated from the downstream end of the first electrode layer. Further, the discharge from the second electrode layer mainly occurs at a position slightly upstream from a portion where the second electrode layer and the rotating member carrying the electrostatic latent image are in contact with each other, in other words, the second electrode layer and the electrostatic latent image This is performed at a position where the supporting rotating body is close. Therefore, the discharge position of the second electrode layer is on the upstream side of the discharge position of the first electrode layer.

In the case where the charged sheet has a laminated structure of three or more layers including the first electrode layer, the insulating layer, and the second electrode layer which is brought into contact with the rotating body carrying the electrostatic latent image, the following static state is required. The toner on the rotating body carrying the latent image can be charged. For example, after the toner on the rotating member carrying the electrostatic latent image is pre-charged by the discharge from the second electrode layer for preliminary static elimination and the like, the toner on the rotating member carrying the electrostatic latent image is discharged by the discharging from the first electrode layer. Can be charged to further remove static electricity.
In this case, the toner on the rotating body carrying the electrostatic latent image can be uniformly charged.

As described above, the downstream end of the first electrode layer may have a shape in which irregularities are arranged in the rotation axis direction of the rotating body carrying the electrostatic latent image. As described above, the first electrode layer may protrude further downstream than the insulating layer and the second electrode layer. As described above, the first electrode layer may be divided into two or more in a direction crossing the rotation direction of the rotating body that carries the electrostatic latent image. Similarly to the first electrode layer, the second electrode layer may be divided into two or more in a direction crossing the rotation direction of the electrostatic latent image bearing rotating body (the rotation axis direction of the electrostatic latent image bearing rotating body). .

When the power supply connected to the first electrode layer of the charging sheet is a DC power supply and the power supply connected to the second electrode layer is also a DC power supply, these DC power supplies may be a common power supply. When the power supply connected to the first electrode layer and the second electrode layer is a common DC power supply, the same voltage may be applied to the first electrode layer and the second electrode layer,
Alternatively, different voltages may be applied by, for example, dividing the voltage with a resistor.

When a DC voltage having the same polarity is applied to each of the first and second electrode layers of the charged sheet to discharge from both the first and second electrode layers, an electrostatic latent image carrying Before the toner on the rotating body reaches the contact portion between the charged sheet and the rotating body carrying the electrostatic latent image, the toner is charged to the same polarity as the first and second electrode layers by discharging from the second electrode layer. Or static electricity can be removed from the toner, and electrostatic attraction of the toner to the first electrode layer and the second electrode layer can be suppressed.

When a voltage obtained by superimposing an alternating voltage (oscillation voltage) on a DC voltage is applied to the second electrode layer of the charged sheet, the toner is rotated by the rotation of the electrostatic latent image bearing rotating member, and the charged sheet and the electrostatic latent image bearing rotation are rotated. When the toner arrives at a contact portion of the body, it is possible to suppress aggregation of the toner at the contact portion. Therefore,
Such agglomerates penetrate between the charged sheet and the electrostatic latent image bearing rotating body, and the distance between the first electrode layer and the peripheral surface of the electrostatic latent image bearing rotating body and the distance between the second electrode layer and the electrostatic latent image bearing rotating body. Variation in the distance between the peripheral surfaces of the rotating body can be suppressed, and a stable discharge can be performed from the first electrode layer and the second electrode layer accordingly. (3) The charged sheet has at least three layers including the electrode layer, the insulating layer provided on the electrostatic latent image bearing rotating body side of the electrode layer, and the electret layer provided on the electrostatic latent image bearing rotating body side of the insulating layer. A part of the electret layer may be brought into contact with a rotating member carrying an electrostatic latent image. For example, the charged sheet is a sheet having a three-layer structure in which an electrode layer, an insulating layer provided on the electrostatic latent image holding rotator side of the electrode layer, and an electret layer provided on the electrostatic latent image holding rotator side of the insulating layer are stacked. Is also good.

In this case, the discharge distance can be adjusted by the thickness of the insulating layer and the electret layer. The electret layer is made of an electret material and has a semi-permanent charge, so that the charged sheet can be electrostatically adsorbed in the direction of the electrostatic latent image bearing rotating body without applying a voltage. Therefore, as compared with the image forming apparatus having the three or more-layered charged sheet including the first electrode layer, the insulating layer, and the second electrode layer to be brought into contact with the rotating member carrying the electrostatic latent image described in (2) above. , Just because there is no need for a power supply to connect to the second electrode layer,
The image forming apparatus can be made compact.

As described above, the downstream end of the electrode layer may have a shape in which irregularities are arranged in the direction of the rotation axis of the rotating body carrying the electrostatic latent image. As described above, the electrode layer may protrude downstream from the insulating layer and the electret layer. As described above, the electrode layer may be divided into two or more in a direction crossing the rotation direction of the electrostatic latent image bearing rotating body (the direction of the electrostatic latent image bearing rotating body rotation axis).

[0050]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 shows a schematic configuration diagram of an example of an image forming apparatus according to the present invention. The image forming apparatus A1 shown in FIG. 1 can form a toner image on the recording sheet R by an electrophotographic image forming process.

In this embodiment, the image forming apparatus A1 includes a photosensitive member 8 as an electrostatic latent image carrying rotary member on which an electrostatic latent image is formed and then the electrostatic latent image is developed to form a toner image. ing.
In this embodiment, the photoconductor 8 has a photoconductive layer 81 formed on a drum-shaped conductive support 82. The conductive support 82 is grounded. In this example, the photoconductor layer 81 is formed by stacking a charge transport layer and a charge generation layer. The charge transport layer is made of a hydrazone derivative in this example. The charge generation layer is made of a bisazo pigment in this example. The charge generation layer may be a phthalocyanine pigment instead of the bisazo pigment. The photoconductor 8 is driven to rotate counterclockwise in the figure by a driving device (not shown).

At the position facing the peripheral surface 83 of the photoconductor 8, the charging charger 411, the laser exposure device 42, the developing device 4
3, a transfer charger 44, a separation charger 45, a charging device D1, a cleaning device 46, and an optical eraser 47 are arranged in this order. The charging charger 411 can apply a voltage from a power supply (not shown) to uniformly charge the peripheral surface 83 of the photoconductor.

The laser exposure device 42 can form an electrostatic latent image on the peripheral surface 83 by irradiating the charged peripheral surface 83 of the photosensitive member with a laser beam and exposing the same. The developing device 43 faces the photoreceptor peripheral surface 83 and is connected to the developing roller 4 connected to the power source PS6.
31. Developing roller 4 for holding charged toner
By applying a developing bias voltage to the power supply 31 from the power supply PS6, the electrostatic latent image on the photosensitive member peripheral surface 83 is developed and visualized,
A toner image can be formed. In this example, reversal development is performed using a negatively charged toner.

The transfer charger 44 can electrostatically transfer the toner image formed on the photoconductor 8 onto the recording sheet R conveyed between the photoconductor 8 and the transfer charger 44. The separation charger 45 removes the charge from the recording sheet R electrostatically adsorbed on the photoconductor 8 and removes the recording sheet R from the photoconductor 8.
Can be easily separated from

The charging device D1 includes a charging sheet S1 partially contacting the photosensitive member peripheral surface 83 and an electrode layer 1 of the charging sheet S1.
01 is provided with a power supply PS1 that can apply a voltage to the power supply. The cleaning device 46 includes a cleaning blade 461 that comes into contact with the peripheral surface 83 of the photoconductor. The cleaning blade 461 can scrape and collect toner on the peripheral surface 83 of the photoconductor.

The light eraser 47 can remove electricity from the peripheral surface 83 of the photoreceptor by irradiating light. The image forming apparatus A1 includes a fixing device 48 for fixing the toner image transferred onto the recording sheet R. Fixing device 48
Has two fixing rollers 481 and 482 opposed to each other. A heat source (not shown) is provided for the fixing roller 481, and the fixing roller 481 is heated to a predetermined fixing temperature during fixing. Further, the fixing roller 482 is pressed toward the fixing roller 481. By passing the recording sheet R between both rollers and applying heat and pressure to the unfixed toner image, the toner image is transferred to the recording sheet R.
Can be established.

Here, the above-described charged sheet S1 and power supply P
The charging device D1 having S1 will be further described. FIG. 2 shows a schematic perspective view of the charging sheet S1. Note that FIG. 2 shows only a part of the photoconductor 8. FIG.
The rotation direction of the photoconductor 8 is indicated by “α”. In the following description, the rotation direction of the photoconductor 8 is simply referred to as “rotation direction”.
May be described. “Upstream in the rotation direction of the photoconductor 8” may be simply referred to as “upstream”. “Downstream in the rotation direction of the photoconductor 8” may be simply referred to as “downstream”.

The charged sheet S1 is a sheet whose area is sufficiently larger than its thickness. The charging sheet S1 is a substantially rectangular flexible sheet in this example. Charge sheet S1
The upstream end is supported by support members 71 and 72 with a predetermined distance from the photoconductor 8. The upstream end of the charging sheet S <b> 1 does not contact the photoconductor 8. Charge sheet S
1 is bent, and a part of the surface on the downstream side is in contact with the photoconductor 8.

The charged sheet S 1 is a sheet composed of two layers, the electrode layer 101 and the insulating layer 31. The insulating layer 31 is disposed on the side facing the photoconductor 8, and a part of the surface of the insulating layer 31 is in contact with the photoconductor 8. The electrode layer 101 is made of an electric resistance material in this example. In this embodiment, the electric resistance material is obtained by dispersing carbon black in polyimide. The volume resistance of the electrode layer 101 is 10 ³ to 10 ⁷ Ω · cm.

The power supply PS 1 is connected to the electrode layer 101. The power supply PS1 can apply a positive or negative DC voltage to the electrode layer 101 by switching an internal switch. Both positive and negative output voltages are variable. Electrode layer 1
To 01, a voltage having the same polarity (in this example, negative polarity) as the normal charging polarity of the toner used during normal development is applied.

In this embodiment, the insulating layer 31 is made of polyimide having excellent abrasion resistance and slidability. The thickness of the insulating layer 31 is set to 80 μm in this example. From the power source PS1 to the electrode layer 101 of the charging sheet S1 and the conductive support 8 of the photoconductor 8
When a voltage is applied during the period 2, the electrode layer 101 can be discharged, and the toner on the photoconductor 8 can be charged. Therefore, it is possible to eliminate the charge from the toner on the photoconductor 8. The charge amount of the toner on the photoconductor 8 can be easily adjusted by adjusting the voltage applied to the electrode layer 101. When the absolute value of the applied voltage is increased,
The charge amount can be increased. The discharge from the electrode layer 101 is mainly generated from the downstream end face of the electrode layer 101.

The image forming apparatus A1 can form a toner image on the recording sheet R as follows. First, the peripheral surface 83 of the photoconductor is sequentially charged by the charging charger 411. An electrostatic latent image is sequentially formed on the charged photoreceptor peripheral surface 83 by laser light from the exposure device 42, and the electrostatic latent image is developed by the developing device 43 using negatively charged toner. As a result, a toner image in which the electrostatic latent image is visualized is formed on the peripheral surface 83 of the photoconductor. The toner image is
The sheet is conveyed by a sheet conveying mechanism (not shown), and is sequentially transferred by the transfer charger 44 onto a recording sheet R sent between the photoconductor 8 and the transfer charger 44. At this time, a positive voltage is applied to the transfer charger from a power supply (not shown).

The recording sheet R to which the toner image has been transferred is neutralized by the separation charger 44, and is easily separated from the photosensitive member 8. The recording sheet R is separated from the photoconductor 8 by its own elasticity while being fed toward the fixing device 48. Thereafter, the recording sheet R is transported to the fixing device 48, and the toner image is fixed on the recording sheet R. On the other hand, the toner remaining on the photosensitive member peripheral surface 83 without being transferred to the recording sheet R is scraped off from the photosensitive member peripheral surface 83 by the cleaning blade 461 of the cleaning device 46 and collected. Further, the residual charges on the photoconductor 8 are optically erased by the optical eraser 47.

The toner remaining on the peripheral surface 83 of the photoreceptor without being transferred onto the recording sheet R is transferred to the transfer charger 4.
In many cases, the charging device D is charged to a polarity opposite to the normal charging polarity (positive in this example) due to the influence of the application of the positive voltage from the cleaning device 46.
1 and a uniform charge can be removed by applying a negative voltage to the electrode 101 of the charged sheet S1 in contact with the surface of the photoreceptor. Can be weakened. This makes it easy to remove the toner by the cleaning blade 461, and
It can be done efficiently. As a result, the cleaning blade 461 can scrape the toner and remove the toner. Therefore, at the time of the next image formation, a better image can be formed. Since the charge is removed from the residual toner using the charging sheet S1, the discharge distance can be shortened as described later, and the generation of ozone can be suppressed accordingly, as compared with the case where the charge is removed by a conventional corona charger.
Therefore, it is possible to suppress the deterioration of the photoconductor 8, the charged sheet S1, and the devices and members arranged near the photoconductor 8, the charged sheet S1.

Even when a part or all of the toner image formed on the photosensitive member 8 is not transferred to the recording sheet R due to a jam or the like in the process of transporting the recording sheet R, the charging device D1 is used. The charge can be removed from the toner before cleaning. Therefore, even when a large amount of toner remains on the photoreceptor 8 due to some abnormality such as a jam in the image forming process, the cleaning device 4
6, the toner can be removed with little unsweeping. When a jam or the like occurs, usually, the transfer charger 4
4 remains in the ON state, the toner on the photoreceptor is almost positively charged by passing through the transfer charger 44. Therefore, in such a case, a negative voltage may be applied to the electrode layer 101 of the charged sheet S1 to remove the charge from the toner. Also, when the transfer charger 44 is stopped to form the AIDC toner pattern on the photoconductor 8 in order to determine the developing bias voltage or the like of the developing device 43, the charging device D1 applies a positive charge to the negatively charged toner pattern. , It is possible to remove the charge from the toner before cleaning. Therefore, when a toner image such as an AIDC toner pattern which is not normally transferred to the recording sheet R is formed on the photoconductor 8 and a large amount of toner remains on the photoconductor 8, the cleaning device 46 removes a small amount of the toner and removes the toner. Can be removed.

In the image forming apparatus A1, the charging device D1 including the charging sheet S1 removes the charge from the toner on the photosensitive member 8.
Therefore, there are the following advantages. To bring a part of the surface of the charged sheet S1 into contact with the photoconductor 8, the electrode layer 1
01 can be easily arranged close to the photoconductor 8. Therefore, the discharge distance can be shortened and the generation of ozone can be suppressed accordingly, as compared with the conventional case where the charge is removed by a corona charger. Further, the arrangement space of the charged sheet S1 can be made smaller than that of the corona charger. Therefore, the entire image forming apparatus can be made compact accordingly.

The electrode layer 101 of the charging sheet S1 is
Therefore, the electrode layer 101 is not damaged, and a stable discharge can be performed for a long period of time. Further, since the electrode layer 101 does not contact the photoconductor 8,
Foreign matter such as toner and paper powder can be prevented from adhering to the electrode layer, and stable discharge can be performed over a long period of time. Since the insulating layer 31 that slides on the photoreceptor 8 is made of a material having excellent wear resistance and slidability, the insulating layer 31 is hardly worn. Therefore, the charge from the toner on the photoconductor 8 can be removed for a longer time by the charging device D1.

When a voltage is applied to the electrode layer 101, an electrostatic attraction force is applied to the electrode layer 101 in the direction of the photoconductor 8, and the downstream side surface of the charged sheet S 1 adheres to the photoconductor 8. Note that the electrostatic attraction force of the charged sheet S1 in the direction of the photoconductor 8 is the same as that of the electrode layer 1.
It can be easily adjusted by adjusting the voltage applied to the voltage V.01. Increasing the absolute value of the applied voltage can increase the electrostatic attraction force. The downstream side surface of the charged sheet S1 is pulled to the downstream side by the rotation of the photoconductor 8 in a state of being electrostatically attracted to the photoconductor 8, so that the charged sheet S1 is
It comes into contact with the photoconductor 8 without sagging or wrinkling.
Further, the charged sheet S1 is changed according to the surface shape of the photosensitive member peripheral surface 83.
Contacts the photoconductor 8. As a result, even if the photosensitive member peripheral surface 83 undulates as the photosensitive member 8 rotates, the distance between the downstream end surface, which is the main discharge point of the electrode layer 101, and the photosensitive member peripheral surface 83 is kept constant. be able to. Thus, the discharge distance can be kept constant, and the electrode layer 101 can discharge more stably. Further, as described above, since the insulating layer 31 is hardly worn, the discharge distance can be kept constant for a long period of time. Therefore, stable charging can be performed by the charging sheet S1 for a long time. Furthermore, since the thickness of the insulating layer 31 is set in the range of 11 to 100 μm as described above, good discharge can be performed from the electrode layer 101 and generation of ozone can be reduced. In the charging sheet S1, the discharge distance can be easily adjusted by the thickness of the insulating layer 31.

Since the electrode layer 101 is made of a resistive material having a volume resistance of 10 ³ to 10 ⁷ Ω · cm as described above, abnormal dot discharge can be prevented, and the photosensitive member 8 due to dot discharge can be prevented.
In addition, it is possible to suppress dielectric breakdown of devices and members disposed around the device. In the image forming apparatus A1, the toner is removed by the cleaning blade 461 that comes into contact with the photoreceptor 8. However, as in the image forming apparatus A2 shown in FIG. The toner may be removed by the cleaning brush 462 that is performed. In this case, the toner is
The toner may be uniformly charged by the charging device D1 so that the toner is easily adsorbed on the toner. The image forming apparatus A
2, devices and parts having substantially the same functions and functions as those of the image forming apparatus A1 are denoted by the same reference numerals. The same applies to the image forming apparatus described below. Further, the image forming apparatus A shown in FIG.
The toner may be removed by using both the cleaning brush 462 and the cleaning blade 461 as shown in FIG.
Cleaning brush 462 and cleaning blade 46
If 1 is used in combination, good cleaning can be performed. In any case, the toner can be charged by the charging device D1 so that the cleaning is facilitated before the cleaning, and the good cleaning can be performed. (2) FIG. 5 shows a schematic configuration diagram of another example of the image forming apparatus according to the present invention.

In the image forming apparatus A4 shown in FIG.
At a position facing the photoconductor 8, a charging brush 412, a laser exposure device 42, a developing device 43, a transfer charger 44, a separation charger 45, and a charging device D1 are arranged in this order.
A voltage is applied from the power supply PS5 to the charging brush 412, and the charging brush 412 is rotationally driven by a driving device (not shown), whereby the photosensitive member peripheral surface 83 can be uniformly charged. The image forming apparatus A4 does not include a dedicated cleaning device for removing the toner on the photoconductor 8.

In the image forming apparatus A4, a toner image is formed on the recording sheet R in the same manner as in the image forming apparatus A1. In the image forming apparatus A4, the toner remaining on the photoconductor 8 is collected as follows. First, the toner remaining on the photoreceptor 8 is charged by the charging device D1 so as to be charged to the normal charging polarity. After that, the rotating charging brush 412 transfers the toner to the peripheral surface 83 of the photoconductor.
The photoreceptor is charged on the surface of the photoreceptor while being dispersed on the surface of the photoreceptor. Thereafter, the toner in the non-exposed area on the photoreceptor is collected by the developing device 43 simultaneously with the development due to the difference between the surface potential of the area on the photoreceptor and the developing bias potential. (3) FIG. 6 shows a schematic configuration diagram of still another example of the image forming apparatus according to the present invention.

The image forming apparatus A5 shown in FIG. 6 is a color image forming apparatus capable of forming a full-color toner image composed of four colors of yellow, magenta, cyan and black on a recording sheet. In the image forming apparatus A5, the photoconductor 8
The charging brush 412 and the laser exposure device 4
2. A developing device 43C capable of developing an electrostatic latent image on the photosensitive member peripheral surface 83 using cyan toner, a developing device 43M capable of developing using magenta toner, and using a yellow toner A developing device 43Y capable of developing, a developing device 43Bk capable of developing using black toner, an intermediate transfer belt 51, a charging device D1, and a cleaning device 46 are sequentially arranged.

The intermediate transfer belt 51 has rollers r1 and r2.
And an endless belt wound around r3. The intermediate transfer belt 51 is in contact with the photoconductor 8. A transfer charger 52 for transferring the toner image formed on the photoconductor 8 to the intermediate transfer belt 51 is disposed at a position on the inner peripheral surface side of the intermediate transfer belt 51 facing the photoconductor 8. A transfer charger 53 for transferring the toner image on the intermediate transfer belt 51 to the recording sheet R is disposed on the outer peripheral surface side of the intermediate transfer belt 51 and facing the roller r3. Roller r on the outer peripheral surface side of intermediate transfer belt 51
At a position facing 1, a cleaning device 54 is further disposed.

The cleaning device 54 has a cleaning blade 541 provided so as to be able to be pressed against and separated from the intermediate transfer belt 51. Cleaning blade 54
By pressing the intermediate transfer belt 1 against the intermediate transfer belt 51, the toner on the intermediate transfer belt 51 can be removed and collected. The image forming apparatus A5 can form a color image on the recording sheet R as follows.

A toner image corresponding to each color of cyan, magenta, yellow, and black is formed on the photoreceptor 8 for each color. Then, each time a toner image of one color is formed, the toner image is electrostatically transferred onto the intermediate transfer belt 51 by the transfer charger 52. The toner images of the respective colors are formed on the photoconductor 8 at a proper timing so that the positions of the toner images of the respective colors on the intermediate transfer belt 51 do not shift. During this time, the cleaning blade 541 of the cleaning device 54 is separated from the transfer belt 51 so as not to disturb the toner image transferred onto the intermediate transfer belt 51.

After all the toner images of each color are transferred onto the intermediate transfer belt 51 and multiple toner images are formed on the intermediate transfer belt 51, the multiple toner images are put together on the recording sheet R and are transferred by the transfer charger 53. Transcribe. After this,
The recording sheet R is sent to the fixing device 48 to fix a multiple toner image. The toner remaining on the photoconductor 8 without being transferred from the photoconductor 8 to the intermediate transfer belt 51 is removed by the cleaning device 4.
6 to remove and collect. Also in the image forming apparatus A5, since the residual toner is removed from the residual toner by the charging device D1 before cleaning and the electrostatic attraction of the toner to the photoconductor 8 can be weakened, good cleaning can be performed. The toner remaining on the intermediate transfer belt 51 without being transferred to the recording sheet R is removed and collected by pressing the cleaning blade 541 against the transfer belt 51. (4) In any of the above-described image forming apparatuses A1 to A5, a voltage applied to the electrode layer of the charged sheet in order to remove electricity from the toner on the photoconductor or to charge the toner to a desired polarity. May be changed in accordance with the following conditions or in accordance with changes in the conditions. The voltage applied to the electrode layer may be changed in proportion to the change in the condition. The voltage applied to the electrode layer may be changed stepwise with respect to the change in the condition.
In any case, if the absolute value of the applied voltage is increased, the amount of charge to the toner can be increased. A voltage according to the environmental temperature may be applied to the electrode layer.

As in the image forming apparatuses A1, A3 and A5,
When the toner is removed by the cleaning blade 461, when the temperature is low, the resilience of the cleaning blade 461 is reduced and the cleaning performance is deteriorated. Good. A voltage according to the environmental humidity may be applied to the electrode layer.

When the environmental humidity is high, the transfer efficiency of the toner image to the recording sheet R or the intermediate transfer belt 51 decreases, and the amount of the toner remaining on the photosensitive member 8 increases. The absolute value of the applied voltage may be increased. A voltage corresponding to the number of times of image formation may be applied to the electrode layer. In the case where toner is removed by the cleaning blade 461 as in the image forming apparatuses A1, A3, and A5, when the number of times of image formation increases, the cleaning blade 461 wears and cleaning performance deteriorates. Therefore, when the number of times of image formation increases, the absolute value of the applied voltage may be larger than when the number is small. The voltage applied to the electrode layer may be changed depending on whether or not the toner image formed on the rotating body carrying the electrostatic latent image has been transferred.

In the image forming process, part or all of the toner image formed on the photosensitive member 8 is not transferred to the recording sheet R or the intermediate transfer belt 51 due to an abnormality such as a jam of the recording sheet R. In this case, the amount of toner remaining on the photoreceptor 8 is larger than when normal image formation is performed. Therefore, when the transfer of the toner image is not performed, the absolute value of the voltage applied to the electrode layer may be larger than when the transfer is performed. When only a part of the toner image is transferred, when the area of the peripheral surface 83 of the photoreceptor holding a large amount of untransferred toner comes to a position facing the electrode layer, the electrodes are adjusted in timing. The absolute value of the voltage applied to the layer may be increased.

When a toner image such as an AIDC toner pattern which is not transferred to a recording sheet R or the like is formed on the photoreceptor 8, the amount of toner to be neutralized by the charging device increases. Therefore, when a toner image that is not transferred to a recording sheet or the like is formed on the photoconductor 8, the polarity of the voltage applied to the electrode layer may be made appropriate and the absolute value may be increased.

The voltage applied to the electrode layer may be changed by combining two or more of the above conditions.
As described above, when changing the voltage applied to the electrode layer of the charging sheet according to the change in the condition, the power supply connected to the electrode layer is set to a variable output voltage power supply, and the output voltage of the power supply is changed according to the change in the condition. What is necessary is just to provide the control part etc. which can be changed. Condition information is input to the control unit. In order to input the condition information, a sensor or the like for detecting condition information such as humidity may be provided in the image forming apparatus as needed. For example, when a voltage corresponding to the environmental temperature and the environmental humidity is applied to the electrode layer, an image forming apparatus A6 shown in FIG. 7 may be used.

The image forming apparatus A6 is an image forming apparatus based on the image forming apparatus A1 shown in FIG. The power supply PS1 that can apply a voltage to the electrode layer 101 of the charging sheet S1 is a variable output voltage power supply. The output voltage of the power supply PS1 is
It can be controlled by the control unit 55. The controller 55 includes the environmental temperature information from the temperature sensor SE1 and the humidity sensor SE2.
Environmental humidity information is input. The control unit 55 controls the voltage applied to the electrode layer 101 based on the environmental temperature information and the environmental humidity information as described above. Thus, even when the environmental temperature and the environmental humidity change, the toner on the photoconductor 8 can be satisfactorily removed by the cleaning device 46.
Note that other condition information is also input to the control unit 55, and the control unit 55 uses the power supply PS1 based on the information.
May be configured to control the output voltage. (5) The structure and configuration of the charging device including the charging sheet for charging the toner on the rotating member carrying the electrostatic latent image are not limited to the structure and configuration of the charging device D1 including the charging sheet S1 described above. Absent. Hereinafter, another example of the charging device will be described.

The charging device described below will be described as a charging device for charging the toner on the photoconductor 8 instead of the charging device D1 in the image forming apparatus A1 shown in FIGS. The charging device described below is an image forming apparatus A2
To A6. The charging sheet included in the charging device described below is supported and arranged similarly to the charging sheet S1 in the charging device D1. In the drawings showing the charging device described below, the rotation direction of the photoconductor is indicated by “α”.

In order to suppress the discharge from the electrode layer of the charged sheet to devices and members other than the rotating member holding the electrostatic latent image, for example, as shown in FIG. The surface opposite to the surface facing the rotating member carrying the latent image may be covered with a second insulating layer. Charge sheet S
Reference numeral 2 denotes a three-layer sheet in which the insulating layer 33, the electrode layer 102, and the insulating layer 31 are sequentially stacked. The insulating layer 31 is disposed on the side facing the photoconductor 8, and a part of the surface of the insulating layer 31 is in contact with the photoconductor 8. The insulating layer 33 is provided on the surface of the electrode layer 102 opposite to the surface facing the photoconductor 8 and covers the surface. Accordingly, it is possible to suppress discharge from the electrode layer 102 to devices and members arranged near the surface of the charged sheet S2 opposite to the surface facing the photoconductor 8, and damage to the devices and members can be suppressed.

When the charged sheet has a laminated structure of two or more layers including an electrode layer and an insulating layer to be brought into contact with the rotating member carrying the electrostatic latent image, the following (5-A) and (5-
B) and (5-C).
What is described in (5-A), (5-B) and (5-C) may be a combination of two or more. (5-A) In order to further stabilize the discharge from the electrode layer, the length of the rotating end (α direction) of the rotating member carrying the electrostatic latent image at the downstream end of the electrode layer is changed, The end portion may have a shape in which irregularities are arranged in the rotation axis direction (direction orthogonal to the α direction) of the rotating body carrying the electrostatic latent image. For example, a charging sheet S3 of the charging device D3 shown in FIG. 9 may be used.

The downstream end of the electrode layer 103 of the charging sheet S3 is formed in a comb shape. The protrusion 103p at the downstream end of the electrode layer 103 does not protrude downstream from the insulating layer 31. When a voltage is applied to the electrode layer 103, the electric field density of the protrusion 103p of the electrode layer 103 increases, so that the protrusion 103p becomes a discharge point. Even when environmental conditions such as temperature and humidity change, and even when used for a long period of time, the discharge point is stable, so that a more stable discharge can be performed. When the pitch of the protrusion 103p of the electrode layer 103 in the rotation axis direction of the photoconductor 8 is set to several tens μm to several hundreds μm,
The toner on the photoconductor 8 can be uniformly charged.

In the charging sheet S 3, the electrode layer 103 is deeper than the insulating layer 31 in the rotation axis direction of the photoconductor 8. In other words, the electrode layer 103 is not formed on the side end of the insulating layer 31 in the rotation axis direction. Accordingly, discharge from the end on the electrode layer 103 side in the rotation axis direction can be suppressed.

The shape of the downstream end portion of the electrode layer may be a saw-tooth shape like the electrode layer 104 of the charging sheet S4 of the charging device D4 shown in FIG. (5-B) The electrode layer may be divided into two or more in the rotation axis direction of the rotating body carrying the electrostatic latent image. For example, a charging sheet S5 of a charging device D5 shown in FIG. 11 may be used.

The electrode layer 105 of the charged sheet S5 is divided into three in the direction of the rotation axis of the photosensitive member 8. Electrode layer 10
5 is three electrode layer parts 105a, 105b, 105c
Consists of Each electrode layer portion 105a, 105b, 105c
The width of the photoconductor 8 in the rotation axis direction is set as follows in accordance with the width and position of the toner image formed on the photoconductor 8 in the rotation axis direction. In this example, the width of the electrode layer portion 105b corresponds to the short side length of the A4 size, and the width of the A4
A vertical size toner image is formed. The A4 vertical size toner image is an A4 size toner image, and the long side direction is the photoconductor rotation direction, and the short side direction is the photoconductor rotation axis direction. Also, three electrode layer portions 105a, 1
The combined width of 05b and 105c corresponds to the long side length of the A4 size, and a toner image of A4 horizontal size is formed on the photoconductor 8 at a position facing these three electrode layer portions.
The A4 size toner image is an A4 size toner image, with the short side direction being the photoconductor rotation direction and the long side direction being the photoconductor rotation axis direction.

The electrode layer portions 105a and 105c are connected to a power supply PS11 to which a positive or negative DC voltage can be applied by switching an internal switch. Electrode layer portion 105
b is connected to a power supply PS12 having the same configuration as the power supply PS11. When a toner image of A4 vertical size is formed on the photoreceptor 8, discharge is performed only from the electrode layer portion 105b. Electrode layer portion 105b facing the peripheral surface 83 region where toner may possibly remain in the photosensitive member peripheral surface 83 region
Since only the discharge is performed, the efficiency is higher and the energy can be saved. When a toner image of A4 horizontal size is formed on the photoreceptor 8, all the electrode layer portions 105a, 105b and 105c are discharged.

The electrode layer portion 105a and the electrode layer portion 1
05b and between the electrode layer portion 105b and the electrode layer portion 105
Between c, an insulator may be inserted to prevent leakage between them. When the AIDC toner pattern is formed on the photoconductor 8, the electrode layer may be divided in the rotation axis direction in accordance with the width and the position of the AIDC toner pattern in the rotation axis direction of the photoconductor in the same manner as described above.
By doing so, it is possible to discharge only from the electrode layer portion facing the AIDC toner pattern, or to increase the applied voltage to the electrode layer portion facing the AIDC toner pattern as described above.

The size and direction of the toner image formed on the photoconductor 8 and the division size and the number of divisions of the corresponding electrode layer are not limited to those described above. For example, the photosensitive member may be finely divided in the rotation axis direction, such as an electrode layer of the charging sheet S6 of the charging device D6 shown in FIG. The electrode layer 106 of the charging sheet S6 is divided into a number of equal widths in the rotation axis direction of the photoconductor 8. In FIG. 12, each of the divided electrode layer portions of the electrode layer 106 is illustrated in a large size for easy understanding. The electrode layer 106 may be divided into, for example, 10 mm in width in the rotation axis direction of the photoconductor. Making the electrode layer 106 into such a finely divided shape can be performed, for example, by forming the electrode layer 106 on the insulating layer 31 by using both a sputtering method and an etching method.

Each divided electrode layer portion of the electrode layer 106 is connected to a power supply. As described above, if the electrode layer is finely divided, toner images (AID
When the C layer (including the C pattern) is formed on the photoreceptor 8, discharge is performed only from the electrode layer portion located at the position facing the toner image of each size, or the electrode layer portion located at the position facing the toner image of each size. Voltage applied to the other electrode layer portion can be changed.

As described above, even when the electrode layer is divided into two or more in the direction of the rotation axis of the rotating body carrying the electrostatic latent image, the downstream end of each of the divided electrode layer portions may be formed as shown in FIGS. And a comb-like shape or a saw-tooth shape as shown in FIG. (5-C) The electrode layer may protrude downstream from the insulating layer. For example, the charging sheet S of the charging device D7 shown in FIG.
7 may be used.

The electrode layer 107 of the charging sheet S7 projects a length L downstream of the insulating layer 31. Such protrusion length L
[Mm] means that the proximity discharge time T is 0.002 to 0.3 [s
ec] (preferably 0.005 to 0.1 [sec])
It is set to be. Proximity discharge time T [se
c] is a value (= L / V) obtained by dividing the protrusion length L by the moving speed V of the photosensitive member peripheral surface 83.

The electric discharge from the electrode layer 107 is
This is mainly performed from the surface 107 s of the protruding end protruding downstream of the insulating layer 31 facing the photoconductor 8. As described above, when the electrode layer 107 is made to protrude downstream from the insulating layer 31, discharge from the electrode layer 107 is facilitated, and uniform and stable discharge can be performed accordingly. Therefore, the toner on the photoconductor 8 can be uniformly charged.

In the case where the charged sheet has a laminated structure of two or more layers including an electrode layer and an insulating layer that is in contact with the rotating member carrying the electrostatic latent image, when the electrode layer protrudes downstream from the insulating layer, The following (5-C1), (5-C2) and (5-C3) may be used. (5-C1) To prevent the protruding end of the electrode layer protruding downstream from the insulating layer from bending or deforming in the direction of the electrostatic latent image bearing rotating body due to electrostatic attraction force, for example, Like the charging sheet S8 of the charging device D8 shown in FIG.
A reinforcing layer may be provided.

In the charging sheet S8, the electrode layer 108 projecting downstream from the insulating layer 31 is
A reinforcing layer 61 is provided on the surface of the photoconductor 8 opposite to the photoconductor 8. The reinforcing layer 61 is made of polyester in this example. Since the bending and deformation of the protruding end portion 108p of the electrode layer 108 in the direction of the photoconductor 8 can be prevented, the discharge distance is stabilized, and a stable discharge can be performed from the electrode layer 108.

It is to be noted that, by increasing the thickness of the electrode layer itself or increasing the thickness of the electrode layer and providing a reinforcing layer, bending and deformation of the protruding end of the electrode layer may be prevented. Also,
The above-mentioned second insulating layer provided on the side opposite to the surface of the electrode layer facing the rotating member carrying the electrostatic latent image may have the function of the reinforcing layer. (5-C2) In order to suppress abnormal discharge from the downstream end face and the edge portion of the downstream protruding end of the electrode layer, for example, the charging sheet S9 of the charging device D9 shown in FIGS. 15A and 15B is used. As described above, the downstream end surface, side end surface, and / or edge portion of the protruding end portion of the electrode layer may be covered with an insulator.

In the charging sheet S9, the electrode layer 109
The downstream end surface 109e, both side end surfaces 109s, and the edge portion of the protruding end portion 109p are covered with the insulator 62. As a result, abnormal discharge from the downstream end surface 109e, both side end surfaces 109s, and the edge portion can be prevented, and the toner on the photoconductor 8 can be uniformly charged accordingly. (5-C3) In order to suppress abnormal discharge from the downstream end surface or the edge of the downstream protruding end of the electrode layer, for example, as in a charging sheet S10 of a charging device D10 shown in FIG. The protruding end may be deflected so that the distance between the protruding end and the rotating member carrying the electrostatic latent image increases as going downstream.

In the charging sheet S10, the insulating layer 31
Protruding end portion 110p of electrode layer 110 protruding further downstream
Are warped so that the distance from the photoconductor 8 increases as going downstream. As a result, the distance between the downstream end surface 110e and the downstream edge portion of the protruding end portion 110p from the photoconductor 8 is larger than that of the other portions, and thus the abnormalities from the downstream end surface 110e and the downstream edge portion are increased. Discharge can be suppressed, and the toner on the photoconductor 8 can be uniformly charged accordingly.

The above (5-C1), (5-C2) and (5
-C3) may be a combination of two or more. The charging sheet of the charging device is not limited to a laminated structure of two or more layers including an electrode layer and an insulating layer that is brought into contact with the rotating member carrying the electrostatic latent image. The charge sheet may have a laminated structure of three or more layers including an electrode layer, as described in the following (6) and (7). Hereinafter, a charging device having such a charged sheet having a laminated structure of three or more layers will be described. In (6), a charging device having a charging sheet having a laminated structure of three or more layers including an electrode layer, an insulating layer, and a second electrode layer to be brought into contact with a rotating member carrying an electrostatic latent image will be described. In (7), a charging device having a charging sheet having a laminated structure of three or more layers including an electrode layer, an insulating layer, and an electret layer to be brought into contact with a rotating body carrying an electrostatic latent image is described. (6) FIG. 17 shows a schematic cross-sectional view of an example of a charging device including a charging sheet having a laminated structure of three or more layers.

The charging device D11 shown in FIG. 17 includes a charging sheet S11 and two power supplies PS1 and PS2.
The charging sheet S11 is formed on the first electrode layer 1 made of a resistance material.
11, a three-layer sheet in which the insulating layer 32 and the second electrode layer 21 are laminated in this order. The second electrode layer 21 is disposed on the side closer to the photoconductor 8, and the downstream surface of the second electrode layer 21 is in contact with the photoconductor 8. The second electrode layer 21 is made of the same resistance material as the first electrode layer in this example.

The first electrode layer 111 is connected to a power supply PS1 capable of outputting a positive or negative DC voltage by switching an internal switch. The power supply P is also applied to the second electrode layer 21.
A power supply PS2 having the same configuration as that of S1 is connected. In this example, a voltage of the same polarity is applied to the first electrode layer 111 and the second electrode layer 21. The insulating layer 32 includes the first electrode layer 1
It is provided between the first electrode layer 11 and the second electrode layer 21 in order to maintain an electrical insulation state therebetween.

The sum of the thickness of the insulating layer 32 and the thickness of the second electrode layer 21 is set so that a good discharge is generated from the downstream end face 111 e of the first electrode layer 111 and the generation of ozone is suppressed. Is set in the range of 11 to 100 μm. In the charging device D11, both the first electrode layer 111 and the second electrode layer 21 of the charging sheet S11 are discharged, and each of the electrode layers 111 and 21 is used for charging the toner on the photoconductor 8. You may. Also, the first electrode layer 1
11 and without discharging from the second electrode layer 21, the second electrode layer 21
It may be used only for electrostatic attraction in the direction. Second
Whether to discharge from the electrode layer 21 can be adjusted by the voltage applied to the second electrode layer 21 from the power supply PS2.

The discharge from the first electrode layer 111 is mainly performed from the downstream end face 111e. The discharge from the second electrode layer 21 is mainly performed at a position slightly upstream of a contact position with the photoconductor 8 where the second electrode layer 21 is close to the photoconductor 8. According to the charging device D11, the toner on the photoconductor 8 can be precharged by the discharge from the second electrode layer 21, and then the toner on the photoconductor 8 can be further charged by the discharge from the first electrode layer 111. . As a result, the toner on the photoconductor 8 can be uniformly charged.

According to the charging device D11, when the toner arrives at a position facing the charged sheet S11 with the rotation of the photosensitive member 8, the second position is set before the toner reaches the contact portion between the charged sheet S11 and the photosensitive member 8. The discharge from the electrode layer 21 removes the charge from the toner, or charges the toner to the same polarity as the electrode layers 21 and 111, so that the toner has the first electrode layer 111 and the second electrode layer 21.
Electrostatic attraction can be suppressed. That is, the first electrode layer 11
Stable discharge can be respectively performed from the first and second electrode layers 21.

As described above, even when the charged sheet has a laminated structure including the first electrode layer, the insulating layer, and the second electrode layer which is brought into contact with the rotating member carrying the electrostatic latent image, the first sheet of the charged sheet can be moved from the first electrode layer. In order to suppress discharge to other than the rotating body carrying the latent image,
The surface of the first electrode layer opposite to the surface facing the rotating member carrying the electrostatic latent image may be covered with a second insulating layer. In the case where the charged sheet has a laminated structure of three or more layers including the first electrode layer, the insulating layer, and the second electrode layer that is brought into contact with the rotating member carrying the electrostatic latent image, the first electrode layer and the second When a voltage of the same polarity is applied to the electrode layers, a single power supply can be connected to these electrode layers, for example, as in a charging device D12 shown in FIG.

The charging device D12 includes only the power source PS3 for applying a voltage to the first electrode layer 111 and the second electrode layer 21. The voltage from the power supply PS3 is divided by the resistors R1 and R2 and applied to the first electrode layer 111 and the second electrode layer 21. Since the number of power supplies is one less than when two power supplies are provided, the entire charging device and thus the entire image forming apparatus can be made compact and low in cost.

When the charged sheet has a laminated structure of three or more layers including the first electrode layer, the insulating layer, and the second electrode layer which is brought into contact with the rotating member carrying the electrostatic latent image, for example, the charging device shown in FIG. As in D13, the alternating voltage may be superimposed on the DC voltage and applied to the second electrode layer. Charging device D1
In 3, the power supply PS2 'is connected to the second electrode layer 21 of the charging sheet S11. The power supply PS2 '
This is a power supply in which a DC power supply PS21 and an alternating power supply PS22 are connected in series. The alternating power supply PS22 is an AC power supply in this example.

In the charging device D13, the second electrode layer 2
1 is applied with a DC voltage superimposed on a DC voltage and discharged from the second electrode layer 21, so that the toner arrives at the contact portion between the charged sheet S 11 and the photoconductor 8 with the rotation of the photoconductor 8. Thus, aggregation of the toner at the contact site can be suppressed. Therefore, such agglomerates form the charged sheet S
11 and the photoconductor 8, the distance between the first electrode layer 111 and the photoconductor peripheral surface 83 and the distance between the second electrode layer 21 and the photoconductor 8.
Of the first electrode layer 111 and the second electrode layer 21 can be stably discharged. The alternating power supply may be configured to be capable of applying a pulse-like or triangular-wave-like alternating voltage instead of a sine-wave AC voltage.

In the charging device D13, the alternating voltage is superimposed on the DC voltage and applied to the second electrode layer to suppress the aggregation of the toner. However, the aggregation of the toner is controlled by, for example, the charging device D14 shown in FIG. It can be suppressed even if only the alternating voltage is applied to the second electrode layer. In the charging device D14, an alternating power supply PS22 is connected to the second electrode layer 21 of the charging sheet S11. The alternating power supply PS22 is an AC power supply in this example.

In the above-described charging apparatus having a charging sheet having a laminated structure of two or more layers including an electrode layer and an insulating layer to be brought into contact with the rotating member carrying an electrostatic latent image, an alternating voltage is superimposed on a DC voltage on the electrode layer. May be applied. The same effect can be obtained. As described above, when the charged sheet has a laminated structure of three or more layers including the first electrode layer, the insulating layer, and the second electrode layer that is brought into contact with the rotating body carrying the electrostatic latent image, the above-mentioned (5-
A), (5-B) and (5-C) in the same manner as described in the following (6-A), (6-B) and (6-C).
As described in C). The same effect can be obtained. What is described in (6-A), (6-B) and (6-C) may be a combination of two or more. (6-A) By changing the length of the downstream end of the first electrode layer in the rotation direction of the electrostatic latent image holding rotator, the downstream end is made uneven in the rotation axis direction of the electrostatic latent image holding rotator. May be arranged. (6-B) The first electrode layer may be divided into two or more in the rotation axis direction of the rotating body carrying the electrostatic latent image. The second electrode layer may also be divided into two or more in the rotation axis direction. Only one of the first electrode layer and the second electrode layer may be divided into two or more in the direction, or both may be divided into two or more in the direction. (6-C) The first electrode layer may be made to protrude downstream from the insulating layer and the second electrode layer. The first electrode layer is formed of an insulating layer and a second
When projecting to the downstream side from the electrode layer, the above-mentioned (5-C
As described in (1), (5-C2) and (5-C3), the following (6-C1), (6-C2) and (6-C3) may be further described. The same effect can be obtained. (6-C1) A reinforcing layer for preventing a protruding end protruding downstream of the first electrode layer from bending or deforming in the direction of the electrostatic latent image bearing rotating body due to electrostatic attraction force. May be provided on the charging sheet. (6-C2) The downstream end face and / or the edge of the downstream protruding end of the first electrode layer may be covered with an insulator. (6-C3) The first electrode layer may be deflected so that the distance between the downstream protruding end of the first electrode layer and the rotating body that carries the electrostatic latent image increases as going downstream.

The above (6-C1), (6-C2) and (6
-C3) may be a combination of two or more. (7) FIG. 21 is a schematic cross-sectional view of another example of a charging device including a charging sheet having a laminated structure of three or more layers. The charging device D15 illustrated in FIG. 21 includes a charging sheet S12 and a power supply PS1.
It has.

The charging sheet S12 is a three-layer sheet in which the electrode layer 112, the insulating layer 32, and the electret layer 22 are laminated in this order. The electret layer 22 is disposed on the side closer to the photoconductor 8, and a part of the surface of the electret layer 22 is in contact with the photoconductor 8. Electret layer 2
2 is made of an electret material.

The electrode layer 112 is connected to a DC power supply PS1 whose output voltage is variable. The sum of the thickness of the insulating layer 32 and the thickness of the electret layer 22 is set so that good discharge is performed from the downstream end face 112 e of the electrode layer 112.
In order to suppress the generation of ozone, it is set in a range of 11 to 100 μm. According to the charging device D15, the toner on the photoconductor 8 can be charged similarly to the charging device D1.

Since the electret layer 22 of the charged sheet S12 that contacts the photoconductor 8 holds electric charge semipermanently, the charged sheet S12 is electrostatically attracted in the direction of the photoconductor 8 without applying a voltage. Therefore, compared to a charging device having a three or more-layered charging sheet including the first electrode layer, the insulating layer, and the second electrode layer that is brought into contact with the electrostatic latent image bearing rotating body, the second electrode layer can be moved to the second electrode layer. Since the power supply for applying voltage is not required, the entire apparatus can be made compact. In addition,
By changing the voltage applied to the first electrode layer 112, the electrostatic attraction force of the charged sheet S12 toward the photoconductor 8 can be changed.

When the charged sheet has a laminated structure including an electrode layer, an insulating layer, and an electret layer that is brought into contact with the rotating body for carrying an electrostatic latent image, the charged sheet can be moved from the electrode layer of the charged sheet to the rotating body for carrying an electrostatic latent image. In order to suppress discharge to other than the surface, the surface of the electrode layer opposite to the surface facing the rotating member for carrying the electrostatic latent image may be covered with a second insulating layer. Further, when the charged sheet has a laminated structure of three or more layers including an electrode layer, an insulating layer, and an electret layer that is brought into contact with the rotating member carrying the electrostatic latent image, the above-mentioned (5-A) and (5- As described in (B) and (5-C), the following (7)
-A), (7-B) and (7-C). The same effect can be obtained. (7-
What is described in A), (7-B) and (7-C) may be a combination of two or more. (7-A) By changing the length of the downstream end of the electrode layer in the rotation direction of the electrostatic latent image holding rotator, the unevenness of the downstream end is aligned in the rotation axis direction of the electrostatic latent image holding rotator. It may be shaped. (7-B) The electrode layer may be divided into two or more in the rotation axis direction of the rotating body carrying the electrostatic latent image. (7-C) The electrode layer may protrude downstream from the insulating layer and the electret layer. When projecting the electrode layer downstream from the insulating layer and the electret layer, the above-mentioned (5)
-C1), (5-C2) and (5-C3), as described in (7-C1) and (7-C2).
And (7-C3). The same effect can be obtained. (7-C1) The protruding end protruding downstream of the electrode layer is
A reinforcing layer may be provided on the charged sheet for preventing the electrostatic latent image from being bent or deformed in the direction of the electrostatic latent image bearing rotating body due to the electrostatic attraction force. (7-C2) The downstream end face and / or the edge of the downstream protruding end of the electrode layer may be covered with an insulator. (7-C3) The electrode layer may be deflected so that the distance between the downstream protruding end of the electrode layer and the rotating member carrying the electrostatic latent image increases as it goes downstream.

(7-C1), (7-C2) and (7-C2)
-C3) may be a combination of two or more.

[0120]

According to the present invention, there is provided an electrophotographic image forming apparatus in which toner remaining on a rotating body carrying an electrostatic latent image such as a photoreceptor is charged with less generation of ozone and the residual toner is easily removed. It is possible to provide an image forming apparatus that can be efficiently removed and collected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present invention.

FIG. 2 is a schematic perspective view of a charged sheet included in the image forming apparatus shown in FIG.

FIG. 3 is a schematic configuration diagram illustrating another example of the image forming apparatus according to the present invention.

FIG. 4 is a schematic configuration diagram showing still another example of the image forming apparatus according to the present invention.

FIG. 5 is a schematic configuration diagram showing still another example of the image forming apparatus according to the present invention.

FIG. 6 is a schematic configuration diagram showing still another example of the image forming apparatus according to the present invention.

FIG. 7 is a schematic configuration diagram showing still another example of the image forming apparatus according to the present invention.

FIG. 8 is a schematic sectional view showing another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 9 is a schematic perspective view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 10 is a schematic perspective view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 11 is a schematic perspective view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 12 is a schematic perspective view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 13 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 14 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 15A is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention, and FIG. 15B is a schematic perspective view of the charging device. .

FIG. 16 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 17 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 18 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 19 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 20 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

FIG. 21 is a schematic sectional view showing still another example of the charging device provided in the image forming apparatus according to the present invention.

[Explanation of symbols]

A1 to A6 Image forming apparatus D1 to D15 Charging device S1 to S12 Charging sheet 101 to 112 Electrode layer 21 Second electrode layer 22 Electret layer 31, 32, 33 Insulating layer 61 Reinforcement layer 62 Insulator 411 Charger (charging device) 412 Charging brush (charging device) 42 Exposure device 43, 43C, 43M, 43Y, 43Bk Developing device 44 Transfer charger (transfer device) 45 Separation charger 46 Cleaning device 461 Cleaning blade 462 Cleaning brush 47 Optical eraser 48 Fixing device 51 Intermediate transfer belt ( Intermediate transfer member) 52 Transfer charger (transfer device) 53 Transfer charger 8 Photoreceptor (Rotating member carrying electrostatic latent image) 83 Photoreceptor peripheral surface α Photoreceptor rotation direction PS1, PS11, PS12, PS2, PS2 ', PS
3, PS4 power supply R record sheet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Shinya Matsuura 2-13-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Naoki Toyoyoshi Azuchicho, Chuo-ku, Osaka-shi 2-3-13 Osaka International Building Minolta Co., Ltd.

Claims (25)

[Claims] 1. An image forming apparatus for forming an image by an electrophotographic image forming process, comprising: an electrostatic latent image bearing rotating body; and a charging member capable of charging a peripheral surface of the electrostatic latent image bearing rotating body. An electrostatic latent image forming apparatus capable of forming an electrostatic latent image on a peripheral surface of the electrostatic latent image bearing rotating body charged by the charging device; and an electrostatic latent image forming apparatus. A developing device capable of developing an electrostatic latent image on the peripheral surface of the rotating body with electrostatic latent image using toner, and toner on the rotating body with electrostatic latent image formed by the developing device A transfer device capable of transferring an image to a transfer-receiving member; and a transfer device for charging the toner on the peripheral surface of the electrostatic latent image-bearing rotating body in a rotational direction of the electrostatic latent image-bearing rotating body. On the downstream side and upstream of the charging device, the static A charged sheet for partially contacting a peripheral surface of a latent image bearing rotating body, comprising an electrode layer and an insulating layer provided on the electrostatic latent image bearing rotating body side of the electrode layer, wherein the electrostatic latent image bearing rotating body A charging sheet that is supported at an upstream end in the rotation direction, and that contacts at least a part of the downstream side of the upstream end with the rotating body that carries the electrostatic latent image, and a power supply that can apply a voltage to the electrode layer An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein said developing device is capable of collecting toner on said rotating body carrying said electrostatic latent image. 3. The electrostatic latent image bearing rotating body is disposed downstream of the transfer device in the rotation direction of the electrostatic latent image bearing rotating body and upstream of the charging device and facing the electrostatic latent image bearing rotating body. A cleaning device capable of removing and collecting the toner on the rotating member carrying the electrostatic latent image, wherein the charged sheet is located downstream of the transfer device in the rotation direction of the rotating member carrying the electrostatic latent image and is provided by the cleaning device; The image forming apparatus according to claim 1, wherein an upstream side of the image forming apparatus is in contact with the peripheral surface of the electrostatic latent image bearing rotating body. 4. The image forming apparatus according to claim 1, wherein said power supply is a power supply to which a DC voltage can be applied. 5. The image forming apparatus according to claim 1, wherein the power supply is a power supply that can apply an alternating voltage to a DC voltage in a superimposed manner. 6. The image forming apparatus according to claim 1, wherein said power supply is a power supply having a variable output voltage. 7. The image forming apparatus according to claim 1, wherein a shortest distance between said electrostatic latent image bearing rotating body and said electrode layer of said charged sheet is set to 11 μm to 100 μm. 8. The battery according to claim 1, wherein the volume resistance of the electrode layer of the charged sheet is 10 ³ Ω · cm to 10 ⁷ Ω · cm.
The image forming apparatus according to any one of the above. 9. A downstream end of the electrode layer of the charged sheet in the rotating direction of the electrostatic latent image bearing rotator, the other end being provided on the electrostatic latent image bearing rotator side with respect to the electrode layer. 9. The image forming apparatus according to claim 1, wherein the image forming apparatus protrudes further downstream in the rotation direction than a downstream end in the rotation direction. 10. 10. An end portion of the charged sheet protruding downstream of the electrode layer in the rotation direction of the rotating body carrying the electrostatic latent image,
The image forming apparatus according to claim 9, wherein a distance between the end portion and the rotating body that carries the electrostatic latent image is warped so as to increase as it goes downstream in the rotation direction. 11. The image forming apparatus according to claim 9, wherein an end surface of the electrode layer of the charged sheet on a downstream side in a rotation direction of the rotating body with the electrostatic latent image is covered with an insulator. 12. The charged sheet according to claim 1, wherein an end of the electrode layer protruding downstream in the rotation direction of the electrostatic latent image bearing rotating body is prevented from bending toward the electrostatic latent image bearing rotating body. The image forming apparatus according to any one of claims 9 to 11, wherein the reinforcing layer is provided on a surface of the electrode layer opposite to a surface facing the rotating member for carrying the electrostatic latent image. 13. The end of the electrode layer of the charged sheet on the downstream side in the rotating direction of the electrostatic latent image bearing rotator has a shape in which irregularities are arranged in a direction crossing the rotating direction of the electrostatic latent image bearing rotator. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed. 14. The image forming apparatus according to claim 1, wherein said electrode layer of said charged sheet is divided into two or more in a direction crossing a rotation direction of said electrostatic latent image bearing rotating body. 15. The charged sheet is a sheet having a laminated structure of two or more layers including the electrode layer and the insulating layer provided on the side of the electrostatic latent image bearing rotator of the electrode layer. 2. An image forming apparatus according to claim 1, further comprising:
15. The image forming apparatus according to any one of items 1 to 14. 16. The charged sheet according to claim 1, wherein the charged sheet is an electrode layer.
The first electrode layer), the insulating layer provided on the electrostatic latent image bearing rotator side of the first electrode layer, and the second electrode layer provided on the electrostatic latent image bearing rotator side of the insulating layer And a power supply capable of applying a voltage to the second electrode layer by bringing a part of the second electrode layer into contact with the rotating member carrying the electrostatic latent image. The image forming apparatus according to claim 1, wherein: 17. The image forming apparatus according to claim 16, wherein said power supply capable of applying a voltage to said second electrode layer is a power supply capable of applying a DC voltage. 18. The image forming apparatus according to claim 16, wherein said power supply capable of applying a voltage to said second electrode layer is a power supply capable of applying an alternating voltage superimposed on a DC voltage. 19. An image forming apparatus according to claim 16, wherein said power supply capable of applying a voltage to said second electrode layer is a power supply having a variable output voltage. 20. The second electrode layer of the charged sheet is two-layered in a direction transverse to a rotation direction of the rotating body for carrying an electrostatic latent image.
20. The image forming apparatus according to claim 16, wherein the image forming apparatus is divided. 21. The charged sheet includes: the electrode layer; the insulating layer provided on the electrode layer on the side of the electrostatic latent image bearing rotating body; and the electret layer provided on the insulating layer on the side of the electrostatic latent image bearing rotating body. The image forming apparatus according to claim 1, wherein the image forming apparatus is a sheet having a laminated configuration of three or more layers including: a part of the electret layer is brought into contact with the rotating member carrying the electrostatic latent image. 22. A voltage according to an environmental temperature can be applied to the electrode layer of the charged sheet.
The image forming apparatus according to any one of the above. 23. The apparatus according to claim 1, wherein a voltage corresponding to environmental humidity can be applied to said electrode layer of said charged sheet.
The image forming apparatus according to any one of the above. 24. The image forming apparatus according to claim 1, wherein a voltage corresponding to the number of times of forming an image can be applied to the electrode layer of the charged sheet. 25. A voltage according to whether or not a toner image formed on the electrostatic latent image bearing rotating body has been transferred to the transfer body can be applied to the electrode layer of the charged sheet. Item 25. The image forming apparatus according to any one of Items 1 to 24.