JP2007079119A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, wherein a successful image is stably obtained over a long period by detecting retention of developer and clogging of a foaming cell of a developer supply member around the developer supply member to return the developing device to a normal state even when the retention and the clogging are about to happen or happen. <P>SOLUTION: The developing device 100 comprised of a developer carrier 106, a regulation member 102 and the supply member 105 and which performs development by impressing bias to the developer carrier 106, is constituted so that a means for measuring minute current flowing to a nip part where the developer carrier 106 contacts with the developer supply member 105 is included, and predetermined bias is impressed between the developer carrier 106 and the developer supply member 105 when drive is stopped, and when a value of the minute current to be measured when reaching a certain threshold or more, the developer supply member 105 is driven so as to be rotated at least one rotation or more at normal rotation speed or faster for a fixed time before the next image formation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a one-component developing device employed in an image forming apparatus such as a copying machine, a facsimile machine, or a printer.

  Conventionally, a one-component developing device has been widely used as one of developing devices used in electrophotographic image forming apparatuses. In a one-component developing device, normally, a one-component toner is frictionally charged by a regulating member such as a blade and a developing roller, a charged toner layer is formed on the developing roller, and development is performed. This is possible and does not require toner concentration control or an agitation process, and is small and excellent in cost. Furthermore, in recent years, in order to improve the image quality, the chances of using a developer having low fluidity as the toner particle size is increasing. For this reason, there are problems such as the retention of the developer around the developer supply member and the clogging of the foam cells of the developer supply member, and the like, causing the rotation unevenness and the damage of the member due to the increase of the shaft torque.

For example, because of this problem, in Patent Documents 1 and 2, in a developing device that supplies toner from a fur brush that rotates in contact with the developing roller with respect to the developing roller, a predetermined voltage is applied to the fur brush, A developing device or the like is disclosed in which a current flowing from the fur brush to the developing roller is detected and toner is supplied to the fur brush until the current value reaches a predetermined value. However, the developer supply amount to the developer carrier is only made constant, and does not serve as means for solving the above problems.
In Patent Document 3, the current flowing between the conductive developer supply roller 9 in contact with the developing sleeve 3 and the developing sleeve is detected to detect the presence or absence of the cartridge. Further, there is disclosed a process cartridge that detects deterioration of the developer supply roller by comparing current values before and after the endurance and notifies a user of a warning before an image defect occurs. However, only a current detection device is provided as means for detecting the presence or absence of the cartridge or the deterioration state of the developer carrying member, and does not solve the problem.
Further, in Patent Document 4, an electric field that attracts the toner on the collecting roller in the direction of the conveying roller is formed, and an electric field that attracts the toner on the conveying roller in the direction of the supplying roller is formed at the opposite portion between the conveying roller and the supplying roller. A developing device having a low-frequency alternating voltage power supply device that applies a low-frequency alternating voltage set so as to the conveying roller is disclosed. However, only a means for recovering the developer from the developer carrying member is provided to prevent the ghost image, and it does not serve as a means for solving the above problems.

Japanese Patent Laid-Open No. 06-051624 Japanese Patent Laid-Open No. 06-149029 JP 09-197943 A Japanese Patent Laid-Open No. 08-278690

  Therefore, the present invention has been made in view of the above problems, and the problem is that the developer stays around the developer supply member or the foam supply cell of the developer supply member is clogged. Alternatively, it is possible to provide a developing device that can detect a situation that has occurred and restore it to a normal state, and can stably obtain a good image over a long period of time.

The features of the present invention, which is a means for solving the above problems, are listed below.
The developing device of the present invention comprises a developer carrying member rotatably provided opposite to an image carrying member, and a non-magnetic one-component developer that is in contact with the developer carrying member and adheres to the developer carrying member. And a regulating member that regulates to a predetermined amount, and a developer supplying member that supplies the developer carrying member with a nonmagnetic one-component developer that is rotatably provided in contact with the developer carrying member. In a developing device for developing an electrostatic latent image on an image carrier by applying a bias to the carrier, means for measuring a minute current flowing in a nip portion where the developer carrier and the developer supply member are in contact with each other In addition, when a predetermined bias is applied between the developer carrying member and the developer supply member when driving is stopped, and the minute current value measured at that time exceeds a certain threshold value, it is constant before the next image formation. Time, usually the developer supply member Characterized in that to be driven to rotate at least one rotation or more at a rotation speed higher.
In addition, the developing device of the present invention includes a developer carrier that is rotatably provided facing the image carrier, and a non-magnetic one-component development that is in contact with the developer carrier and adheres to the developer carrier. A regulating member for regulating the amount of the developer to a predetermined amount, a developer supplying member that supplies the developer carrying member with a nonmagnetic one-component developer that is rotatably provided in contact with the developer carrying member, and the developer supply A developer collecting member provided in contact with the member and spaced apart from the developer carrier, and developing a latent electrostatic image on the image carrier by applying a bias to the developer carrier; In the apparatus, there is provided means for measuring a minute current flowing in a nip portion where the developer carrier and the developer supply member are in contact with each other and a predetermined gap is provided between the developer carrier and the developer supply member when driving is stopped. Bias applied and measured at that time When the minute current value exceeds a threshold value, the developer supply member is driven to rotate at least once or more for a certain time before the next image formation, and the developer recovery member is normally charged nonmagnetic A bias in a direction in which the one-component developer moves from the developer supply member to the developer recovery member is applied.
In addition, the developing device of the present invention includes a developer carrier that is rotatably provided facing the image carrier, and a non-magnetic one-component development that is in contact with the developer carrier and adheres to the developer carrier. A regulating member that regulates a predetermined amount of the developer, a developer supply member that supplies the developer carrier with a nonmagnetic one-component developer that is rotatably provided in contact with the developer carrier, and the developer supply member A developing device that develops an electrostatic latent image on the image carrier by applying a bias to the developer carrier, the developer collecting member being provided at a position that is in contact with the developer carrier and spaced apart from the developer carrier And a means for measuring a minute current flowing in a nip portion where the developer carrier and the developer supply member are in contact with each other, and a predetermined bias between the developer carrier and the developer supply member when driving is stopped. Applied and measured at that time When the small current value exceeds a certain threshold value, the developer supply member is driven to rotate at least one rotation at a normal rotation speed for a certain time before the next image formation, and the developer recovery member is charged normally. A bias in a direction in which the nonmagnetic one-component developer moves from the developer supply member to the developer recovery member is applied.
In the developing device of the present invention, the developer carrying member, the developer supplying member, and the developer collecting member are all composed of a conductive or semiconductive member.
The developing device of the present invention is characterized in that the developer supply member has a rotatable roller shape, and the surface thereof is constituted by a foam member or a brush member having pores.
In the developing device of the present invention, the developer recovery member is a rotatable roller shape, and the surface thereof is constituted by a foam member or a brush member having pores.
A process cartridge according to the present invention includes at least the developing device described above, and is detachable from the image forming apparatus.
The image forming apparatus of the present invention includes at least the developing device described above.

As described above, according to the present invention, it is possible to detect the stagnation of the developer in the vicinity of the developer supply member and the clogging of the developer to the developer supply member, and sequentially return to the normal state. Thus, a good image can be obtained over a long period of time.
In addition, since the developer carrier, the developer supply member, and the developer recovery member are composed of conductive or semiconductive members, it is possible to apply a bias between the constituent members. It is possible to move the developer. Further, the developer supplying member and the developer collecting member are made of foam members and brushes, and the contact pressure at the contact portion is reduced, so that it is possible to reduce damage to the developer. Degradation can be suppressed, and a good image can be stably obtained over a long period of time.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 shows an electrophotographic copying apparatus as an image forming apparatus used in an embodiment of the present invention. In FIG. 1, an electrophotographic copying apparatus 1 includes an exposure unit 2 and a process cartridge 3.
Y, 3C, 3M, 3Bk, transfer device 4 and the like.

The exposure unit 2 includes a polygon mirror, a plurality of reflection mirrors, a lens, and the like therein, and emits light emitted from a laser beam scanner using a laser diode or a light emitting unit such as an LED to each process cartridge 3Y, 3C, 3M. , 3Bk.

  Below the exposure means 2, each process cartridge 3Y, 3C, 3M, 3Bk is arranged. Each process cartridge 3Y, 3C, 3M, 3Bk has the color of non-magnetic one-component developer (hereinafter referred to as toner) stored inside (yellow for 3Y, blue for 3C, red for 3M, black for 3Bk). Except for the above, each is configured in the same manner, and is provided detachably with respect to the main body of the image forming apparatus 1 by a stopper (not shown).

Hereinafter, the process cartridge 3Y will be described with reference to FIG. In the other process cartridges 3C, 3M, 3Bk, the last symbol Y of each component constituting the process cartridge 3Y is replaced with the same symbols C, M, Bk as the process cartridges 3C, 3M, 3Bk. .
The process cartridge 3Y has a photosensitive drum 5Y as an image bearing member in a substantially central portion of the cartridge main body 9Y, and a charging roller 6Y, a cleaning means 7Y, and a characteristic portion of the present invention. A developing device 8Y is provided. The photosensitive drum 5Y is
The drum is driven in a clockwise direction in FIG. 2 by a drum driving means (not shown).

The charging roller 6Y is rotatably supported by the cartridge main body 9Y, and its peripheral surface is pressed against the surface of the photosensitive drum 5Y by a biasing force of a biasing means (not shown), and the photosensitive drum is driven by a drum driving means (not shown). When 5Y is rotationally driven, it rotates following this. A predetermined bias voltage is applied to the charging roller 6Y from a high voltage power source (not shown), whereby the surface of the photosensitive drum 5Y is charged to -500V.

A cleaning unit 7Y is disposed below the charging roller 6Y. The cleaning means 7Y has a cleaning blade 10Y made of an elastic body that contacts the surface of the photosensitive drum 5Y with a predetermined contact pressure, and a cleaning brush 11Y that slides on the surface of the photosensitive drum 5Y. The residual toner that has not been transferred from the surface of 5Y is removed. The cleaning brush 11Y is composed of a conductive elastic body, and is connected to the ground to clean the surface of the photosensitive drum 5Y and to remove static electricity. Below the cleaning brush 11Y, a developer transport roller 12Y ′ that transports the toner removed from the surface of the photoreceptor drum 5Y is disposed.

A developing device 8Y is disposed above the photosensitive drum 5Y. The developing device 8Y supplies toner to the photosensitive drum 5Y and develops an electrostatic latent image formed on the surface of the photosensitive drum 5Y so as to visualize the electrostatic latent image on the surface of the developing roller 12Y and the developing roller 12Y. A blade-like developer regulating member 13Y that performs main charging of the toner while regulating the layer thickness of the adhered toner, a supply roller 14Y as a developer feeding member that feeds the toner to the developing roller 12Y, and residual toner that has not been used for development Are provided in contact with the peripheral surface of the developing roller 12Y, a toner hopper 17Y for storing yellow toner, an agitator 18Y for conveying toner from the toner hopper 17Y to the supply roller 14Y, and the like. Have.

The developing roller 12Y to which a predetermined bias voltage is applied from a high voltage power source (not shown) is rotatably supported by the casing 15Y, and is counterclockwise in FIG. 2 which is opposite to the photosensitive drum 5Y by a developing roller driving means (not shown). In the rotating direction, the photosensitive drum 5Y is rotationally driven at a linear velocity that is 1.0 to 2.0 times the linear velocity of the photosensitive drum 5Y. The agitator 18Y is rotationally driven in a counterclockwise direction in FIG. 2 by driving means (not shown), and sends the toner to the supply roller 14Y.

The supply roller 14Y is rotatably supported on the casing 15Y via a bearing (not shown), and is press-contacted with a predetermined pressure contact force so as to form a predetermined nip width with respect to the developing roller 12Y. Along with the developing roller 12Y by the frictional force received from the contact portion with 12Y, it is driven to rotate clockwise in FIG.

The base of the developer regulating member 13Y is attached to the casing 15Y, and the free end thereof is pressed against the surface of the developing roller 12Y with a predetermined pressing force. When the toner supplied to the surface of the developing roller 12Y passes through the developer regulating member 13Y, the toner passing amount is adjusted to be constant, and a uniform toner thin layer is formed on the surface of the developing roller 12Y. As the developer regulating member 13Y, a conductive thin plate (thickness of about 60 to 100 μm) such as SUS or phosphor bronze or a conductive resin coat applied thereto is used, and toner is applied to the developer regulating member 13Y. By applying a bias voltage in the direction to adhere to 12Y, the toner that has passed through the developer regulating member 13Y is triboelectrically charged by the surfaces of both the developer regulating member 13Y and the developing roller 12Y, and at the same time, charge injection is performed. Therefore, a stable charge amount can be given to the toner used for development on the photosensitive drum 5Y.

1 and 2 show an example in which the surface of the developing roller 12Y is in contact with the surface of the photosensitive drum 5Y, but the surface of the photosensitive drum 5Y and the surface of the developing roller 12Y may be in a non-contact state. Good. In addition, an example in which the drum-shaped photosensitive drum 5Y is used as the image carrier has been described, but a belt-like one may be used as the image carrier.

With the above-described configuration, the developing roller 12Y having an appropriate amount of toner thin layer formed on the surface thereof is opposed to the photosensitive drum 5Y in a contact state or a non-contact state, and a predetermined bias voltage is applied to the development roller 12Y. Then, toner is supplied from the developing roller 12Y to the electrostatic latent image formed on the surface of the photosensitive drum 5Y to perform a developing operation. The toner on the developing roller 12Y that has not been supplied to the photosensitive drum 5Y passes through the inlet seal 16Y without being scraped off by the inlet seal 16Y, and the newly supplied toner is added to the nip portion with the supply roller 14Y. Then, the process proceeds to the next toner thin layer forming step.

A transfer device 4 is disposed below each process cartridge 3Y, 3C, 3M, 3Bk. The transfer device 4 includes an intermediate transfer belt 19 and primary transfer rollers 20Y, 20C, 20M, 2
0Bk, secondary transfer roller 21, belt cleaning device 22 and the like.

The intermediate transfer belt 19 is stretched around a driving roller 23 and driven rollers 24, 25, and 26, and is moved in the direction indicated by the arrow in FIG. Is done. The surface of the intermediate transfer belt 19 is the photosensitive drum 5.
It arrange | positions in the aspect which contacts the surface of Y, 5C, 5M, and 5Bk, respectively.

Primary transfer rollers 20Y, 20C, 20M, and 20Bk are disposed at positions facing the respective photosensitive drums 5Y, 5C, 5M, and 5Bk via the intermediate transfer belt 19. The primary transfer rollers 20Y, 20C, 20M, and 20Bk are respectively connected to the photosensitive drums 5Y, 5C, 5M, and 5Bk.
The photosensitive drums 5Y, 5C are each supported by a predetermined primary transfer bias voltage applied to each primary transfer roller 20Y, 20C, 20M, 20Bk from a high voltage power source (not shown). , 5M, and 5Bk are sequentially transferred onto the surface of the intermediate transfer belt 19.

A secondary transfer roller 21 is disposed at a position facing the drive roller 23 via the intermediate transfer belt 19. The secondary transfer roller 21 rotatably supported by the image forming apparatus main body is disposed in pressure contact with the driving roller 23, and a predetermined secondary transfer bias voltage is applied to the secondary transfer roller 21 from a high voltage power source (not shown). As a result, the full-color image formed on the intermediate transfer belt 19 is transferred to the paper 27 as a transfer material fed toward the pressure contact portion between the secondary transfer roller 21 and the drive roller 23. The paper 27 to which the image has been transferred is fixed on the image transferred by a fixing device (not shown) and then discharged onto a predetermined paper discharge tray (not shown). Also,
The toner remaining on the intermediate transfer belt 19 without being transferred onto the paper 27 by the secondary transfer roller 21 is collected by the belt cleaning device 22.

FIG. 3 is a schematic diagram for explaining the configuration of the developing device of the present invention.
As shown in FIG. 3, in the developing device 100, the developer loosening member 103 provided in the developer accommodating portion 101 rotates clockwise or counterclockwise to loosen the accommodated developer. At the same time as the developer in the container 101 is loosened, it moves to the vicinity of the developer supply member 105 by its own weight. The developer supply member 105 provided in the developer accommodating portion 101 is a roller-shaped rotating body covered with a foam material having a structure having pores (cells) on the surface or a roller shape covered with a brush. It is disposed in contact with the developer carrier 106.
Particularly desirable as the developer supply member 105 is a roller shape coated with a foam material having a structure having pores (cells) on the surface, and is disposed in contact with the developer carrier 106.

The surface of the roller-shaped developer supply member 105 covered with the foam material is coated with a foam material having a structure having pores (cells), and the developer adhesion amount on the developer supply member 105 is secured. Further, the deterioration of the developer due to the pressure concentration at the contact portion with the developer carrier 106 is prevented. In addition, a conductive material containing carbon fine particles or an ionic conductive material is used as the foam material, and the electric resistance value of the developer supply member 105 is set to 10 ³ to 10 ¹² Ω. At the time of image formation, AC is applied to the developer supply member 105 with a DC bias offset in the direction opposite to the developer charging polarity with respect to the developing bias or a DC bias offset in the direction opposite to the developer charging polarity with respect to the developing bias. A bias superimposed bias is often applied, but the DC bias offset in the same direction as the developer charging polarity with respect to the developing bias or offset in the same direction as the developer charging polarity with respect to the developing bias. Even when a bias obtained by superimposing an AC bias on the DC bias is applied, the same bias as the developing bias may be applied.
In FIG. 3, the developer supply member 105 rotates counterclockwise and supplies the developer placed on the surface onto the developer carrier 106.

For the developer carrying member 106, a roller coated with an elastic rubber layer is used, and a surface coat layer made of a material that is easily charged to a polarity opposite to that of the developer is provided on the surface.
The elastic rubber layer is set to a hardness of 60 degrees or less according to JIS-A in order to prevent developer deterioration due to pressure concentration at the contact portion with the regulating member 102. The surface roughness is set to 0.3 to 2.0 μm as Ra, and a necessary amount of developer is held on the surface. Further, since a developing bias is applied to the developer carrying member 106 to form an electric field with the image carrying member 200, the elastic rubber layer is set to a resistance value of 10 ³ to 10 ¹⁰ Ω. The developer carrier 106 rotates counterclockwise, and conveys the developer held on the surface to a position facing the regulating member 102 and the image carrier 200.

  The regulating member 102 may be provided at a position lower or higher than the contact position between the developer supply member 105 and the developer carrier 106, but from the contact position between the developer supply member 105 and the developer carrier 106. It is desirable to be provided at a higher position. The regulating member 102 is made of a metal leaf spring material such as SUS or phosphor bronze, and the free end is brought into contact with the surface of the developer carrier 106 with a pressing force of 10 to 40 N / m, and passes under the pressure. The developed developer is thinned and charged by triboelectric charging. Further, in order to assist frictional charging, the regulating member 102 is offset in the same direction as the developer charging polarity with respect to the DC bias or the developing bias offset with respect to the developing bias in the same direction as the developer charging polarity. A bias obtained by superimposing an AC bias on a DC bias is applied. The image carrier 200 rotates in the clockwise direction in FIG. 3, and therefore the surface of the developer carrier 106 moves in the same direction as the traveling direction of the image carrier 200 at a position facing the image carrier 200. The thinned developer is conveyed to a position facing the image carrier 200 by the rotation of the developer carrier 106, and the developing bias applied to the developer carrier 106 and the electrostatic latent on the image carrier 200. In accordance with the latent image electric field formed by the image, it moves to the surface of the image carrier 200 and is developed. An inlet seal is provided in contact with the developer carrier 106 at a portion where the developer left on the developer carrier 106 without being developed on the image carrier 200 returns to the developer accommodating portion 101 again. The developer is sealed so as not to leak out of the developing device 100. In FIG. 3, the developer carrier 106 and the image carrier 200 are shown in contact with each other, but they may be arranged in a non-contact manner. Further, although the image carrier 200 is described as a drum shape, it may be a belt shape.

  A microammeter 300 and a variable voltage power source 301 are provided between the semiconductive developer carrier 106 and the semiconductive developer supply member 105, and a signal can be sent from the microammeter to the control circuit 302. In the developing device 100 shown in FIG. 3 configured as described above, a DC bias of 100 V to 200 V is applied between the developer carrier 106 and the developer supply member 105 when the driving of the developing device 100 is stopped other than during image formation. Apply. If the minute current value at that time is about 0 μA to 1 μA, it is determined that the state of the developer around the developer supply member 105 is normal, and the next image formation starts in that state. If it is about 3 μA to 10 μA, it is determined that the state of the developer around the developer supply member 105 is abnormal (the developer stays or the foamed cells of the developer supply member 105 are clogged), and the developer supply member After 105 is driven about 5 to 10 times at a speed 30% to 50% higher than the normal rotation speed, image formation is started.

FIG. 4 is a schematic view for explaining the configuration of the developing device of the present invention that also includes a developer recovery member. The developer recovery member 104 is provided at a position that contacts the developer supply member 105 and is separated from the developer carrier 106.
A microammeter 300 and a variable voltage power source 301 are provided between the semiconductive developer carrier 106 and the semiconductive developer supply member 105, and a signal can be sent from the microammeter to the control circuit 302. In the developing device 100 shown in FIG. 4 having the configuration, a DC bias of 100 V to 200 V is applied between the developer carrier 106 and the developer supply member 105 when the driving of the developing device 100 is stopped except during image formation. Apply. If the minute current value at that time is about 0 μA to 1 μA, it is determined that the state of the developer around the developer supply member 105 is normal, and the next image formation starts in that state. If it is about 3 μA to 10 μA, it is determined that the state of the developer around the developer supply member 105 is abnormal (the developer stays or the foamed cells of the developer supply member 105 are clogged), and the developer supply member At the same time as rotating 105 at a normal rotation speed, the developer collecting member 104 is supplied with a DC bias or developer that is offset in the direction opposite to the charging polarity of the developer with respect to the bias applied to the developer supplying member 105. A bias obtained by superimposing an AC bias on a DC bias offset in a direction opposite to the charging polarity of the developer with respect to the bias applied to the member 105 is applied. This bias acts in the direction in which the developer adsorbed on the developer supply member 105 is attracted to the developer recovery member 104.

  A microammeter 300 and a variable voltage power source 301 are provided between the semiconductive developer carrier 106 and the semiconductive developer supply member 105, and a signal can be sent from the microammeter to the control circuit 302. In the developing device 100 shown in FIG. 4 having the configuration, a DC bias of 100 V to 200 V is applied between the developer carrier 106 and the developer supply member 105 when the driving of the developing device 100 is stopped except during image formation. Apply. If the minute current value at that time is about 0 μA to 1 μA, it is determined that the state of the developer around the developer supply member 105 is normal, and the next image formation starts in that state. If it is about 3 μA to 10 μA, it is determined that the state of the developer around the developer supply member 105 is abnormal (the developer stays or the foamed cells of the developer supply member 105 are clogged), and the developer supply member 105 is driven about 5 to 10 times at a speed 30% to 50% higher than the normal rotation speed, and at the same time, the developer recovery member 104 is developed with respect to the bias applied to the developer supply member 105. A bias obtained by superimposing an AC bias on a DC bias offset in a direction opposite to the charging polarity of the developer or a DC bias offset in a direction opposite to the charging polarity of the developer with respect to a bias applied to the developer supply member 105 Apply, then enter image formation.

The developer carrying member 106 provided in the developing device 100 shown in FIG. 4 uses a roller coated with an elastic rubber layer, and further has a surface coat layer made of a material that is easily charged with a polarity opposite to that of the developer. Is provided. The elastic rubber layer is set to a hardness of 60 degrees or less according to JIS-A in order to prevent developer deterioration due to pressure concentration at the contact portion with the regulating member 102. The surface roughness is set to 0.3 to 2.0 μm as Ra, and a necessary amount of developer is held on the surface. Further, since a developing bias is applied to the developer carrying member 106 to form an electric field with the image carrying member 200, the elastic rubber layer is set to a resistance value of 10 ³ to 10 ¹⁰ Ω. The developer supply member 105 provided in the developing device 100 uses a roller-shaped rotating body covered with a foam material having a structure having pores (cells) on its surface or a roller-shaped rotating body covered with a brush. It is disposed in contact with the agent carrier 106. What is particularly desirable as the developer supply member 105 is a roller-shaped developer supply member coated with a foam material having a structure having pores (cells) on the surface thereof, and is coated with the foam material. The surface of 105 is covered with a foam material having a structure having pores (cells), and the foam material is made of a conductive material containing carbon fine particles or an ionic conductive material. The value is set to 10 ³ to 10 ¹² Ω. Specific materials include those obtained by adding carbon to an ethylene propylene copolymer foam, and those obtained by adding carbon to a polyurethane foam, and the average number of cells is 30/25 mm to 70 mm. A piece / 25 mm is desirable.

The developer collecting member 104 provided in the developing device 100 is a metal roller, a roller covered with a foam material having a structure having a hole (cell) on the surface, or a roller covered with a brush of an electronically conductive material. In the case of a metal roller as a developer collecting member, the material itself is conductive and there is no problem. However, when a roller covered with a foam material having a structure with pores (cells) on the surface is used, the roller The surface is covered with a foam material having a structure having pores (cells), and the foam material is made of a conductive material containing carbon fine particles or an ionic conductive material. 10 ³ to 10 ¹² Ω is set.

  The developing device 100 is provided in an integrated cartridge together with the image carrier 200, the cleaning device, and the charging device to constitute a process cartridge, and the process cartridge is detachably attached to the apparatus main body.

  The image forming apparatus includes a developing device 100 as described in the first to eighth aspects.

1 is a schematic front view of an electrophotographic copying apparatus as an image forming apparatus employing an embodiment of the present invention. It is the schematic which showed the process cartridge used for one Embodiment of this invention. It is the schematic for demonstrating the structure of the image development apparatus of this invention. It is the schematic for demonstrating the structure of the image development apparatus of this invention provided also with the developer collection | recovery member.

Explanation of symbols

1 Image forming device (electrophotographic copying machine)
2 Exposure means 3Y, 3C, 3M, 3Bk Process cartridge 4 Transfer device 5Y, 5C, 5M, 5Bk Image carrier (photosensitive drum)
6Y, 6C, 6M, 6Bk Charging rollers 7Y, 7C, 7M, 7Bk Cleaning means 8Y, 8C, 8M, 8Bk Developing device 9Y Cartridge body 10Y Cleaning blade 11Y Cleaning brushes 12Y, 12C, 12M, 12Bk Developer carrier (developing roller) )
12Y 'developer transport roller 13Y developer regulating members 14Y, 14C, 14M, 14Bk developer supply member (supply roller)
15Y Casing 16Y Entrance seal 17Y Toner hopper 18Y Agitator 19 Intermediate transfer belts 20Y, 20C, 20M, 20Bk Primary transfer roller 21 Secondary transfer roller 22 Belt cleaning device 23 Drive rollers 24, 25, 26 Drive roller 27 Paper 100 Developing device 101 Developer Inner part 102 Control member 103 Developer loosening member 104 Developer recovery member 105 Developer supply member 106 Developer carrier 200 Image carrier 300 Microammeter 301 Power supply 302 Control circuit

Claims (8)

A developer carrier that is rotatably provided opposite the image carrier;
A regulating member that abuts the developer carrier and regulates the non-magnetic one-component developer adhered to the developer carrier to a predetermined amount;
A developer supply member that supplies the developer carrier with a nonmagnetic one-component developer that is rotatably provided in contact with the developer carrier;
In a developing device for developing an electrostatic latent image on an image carrier by applying a bias to the developer carrier,
While providing a means for measuring a minute current flowing in the nip portion where the developer carrier and the developer supply member are in contact,
When a predetermined bias is applied between the developer carrying member and the developer supply member when the driving is stopped, and the minute current value measured at that time exceeds a certain threshold value, the predetermined time before the next image formation, A developing device, wherein the developer supply member is driven to rotate at least one rotation at a normal rotation speed or more. A developer carrier that is rotatably provided opposite the image carrier;
A regulating member that abuts the developer carrier and regulates the non-magnetic one-component developer adhered to the developer carrier to a predetermined amount;
A developer supply member that supplies the developer carrier with a non-magnetic one-component developer that is rotatably provided in contact with the developer carrier;
A developer recovery member provided in contact with the developer supply member and spaced from the developer carrier;
In a developing device for developing an electrostatic latent image on an image carrier by applying a bias to the developer carrier,
Means is provided for measuring a minute current flowing in a nip portion where the developer carrier and the developer supply member are in contact, and a predetermined bias is applied between the developer carrier and the developer supply member when driving is stopped. When the minute current value measured at that time exceeds a threshold value, the developer supply member is driven to rotate at least once or more for a predetermined time before the next image formation, and the developer recovery member is A developing device characterized by applying a bias in a direction in which a normally charged non-magnetic one-component developer moves from the developer supply member to the developer recovery member. A developer carrier that is rotatably provided opposite the image carrier;
A regulating member that abuts the developer carrier and regulates the non-magnetic one-component developer adhered to the developer carrier to a predetermined amount;
A developer supply member that supplies the developer carrier with a non-magnetic one-component developer that is rotatably provided in contact with the developer carrier;
It is composed of a developer recovery member provided at a position in contact with the developer supply member and spaced from the developer carrier,
In a developing device for developing an electrostatic latent image on an image carrier by applying a bias to the developer carrier,
Means is provided for measuring a minute current flowing in a nip portion where the developer carrier and the developer supply member are in contact, and a predetermined bias is applied between the developer carrier and the developer supply member when driving is stopped. When the minute current value measured at that time exceeds a certain threshold value, the developer supply member is driven to rotate at least one rotation at a normal rotation speed for a certain period of time before the next image formation and the development. A developing device characterized in that a bias is applied in such a direction that the non-magnetic one-component developer that is normally charged on the developer recovery member moves from the developer supply member to the developer recovery member. The developer according to any one of claims 1 to 3, wherein the developer carrying member, the developer supply member, and the developer collecting member are all composed of a conductive or semiconductive member. apparatus. 5. The developing device according to claim 1, wherein the developer supply member has a rotatable roller shape, and a surface thereof is formed of a foam member or a brush member having pores. . 6. The development according to claim 2, wherein the developer collecting member has a rotatable roller shape, and a surface thereof is constituted by a foam member or a brush member having pores. apparatus. A process cartridge comprising at least the developing device according to any one of claims 1 to 6 and detachable from an image forming apparatus. An image forming apparatus comprising at least the developing device according to claim 1.

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