JP2006259577A - Development apparatus and image forming apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development apparatus in which a developer charge amount and a developer amount on a developer carrier are uniformized, the change of the developer charge amount and the developer amount is small even at the time of use over a long period of time and the fluidity of a developer inside the apparatus or the like is stabilized as well further, and an image forming apparatus using it. <P>SOLUTION: The development apparatus comprises: a freely turnable developer carrier 2 opposing an image carrier 1 carrying electrostatic latent images, for carrying a developer on the surface; a developer supply member 3 disposed at a position opposing the developer carrier 2 on the upstream side in a developer carrying direction of the opposing part of the image carrier 1 and the developer carrier 2, for supplying the developer to the developer carrier; and a discharge member 4 disposed at a position opposing the developer carrier 2 on the downstream side in the developer carrying direction of the opposing part of the image carrier 1 and the developer carrier 2 and on the upstream side of the developer supply member 3, for eliminating the static of the residual developer on the developer carrier 2. For the static elimination member 4, at least the surface facing the developer carrier 2 is constituted of a semiconductive resin layer 4a including only an ion conductive material 8 as a conductive agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to a developing device using a one-component developer and an improvement of an image forming apparatus using the developing device.

  As a developing device used in a conventional image forming apparatus such as an electrophotographic method, a one-component developing method using a one-component developer consisting only of toner and a two-component developing method using a two-component developer consisting of toner and a carrier. Is known. Among them, the one-component development type developing device does not require mixing with the carrier, stirring, and toner concentration control, so that the device can be reduced in size and cost, and further, the developer can be replaced. Since it is unnecessary, it is increasingly used mainly in printers that require maintenance-free operation.

In recent years, such a developing device has come to be used particularly in a color image forming apparatus. However, in order to form a color image, each color toner such as yellow, magenta, cyan, and black is completely used. It is necessary to develop a color by melting it. Further, in order to meet the demand for energy saving and speeding up of the color image forming apparatus, a binder resin used for the toner is selected such that it melts at a lower temperature.
Therefore, since the toner easily deteriorates due to the stress applied to the toner in the developing device, how to reduce the stress applied to the toner in the developing device is a developing device that can be used stably over a long period of time. It has become an important requirement.

Japanese Patent Laid-Open No. 6-167871 (Example, FIG. 5) JP 2000-10404 A (Embodiment of the Invention, FIG. 1) JP 2002-72687 A (Embodiment of the Invention, FIG. 2)

  In order to solve such problems, there are disclosed methods for newly providing a scraping member for scraping off the toner on the developing roll, or providing a static eliminating member for removing the toner on the developing roll so that the toner is easily separated from the developing roll. Has been. That is, by reducing the residual toner on the developing roll, ghost prevention (a phenomenon in which a development history due to a difference in toner consumption required for development appears as a shading in an image to be developed next) is performed. The amount of toner peeled off from the developing roll by the toner supply roll can be reduced, and the pressure contact force between the developing roll and the toner supply roll can be reduced. As a result, less stress is applied to the toner.

In the method of providing the scraping member, the stress on the toner by the scraping member cannot be ignored, it is difficult to maintain the scraping performance, the uniformity of the toner layer formed on the developing roll is impaired, There is a possibility that density unevenness on the image may occur or white stripes may be generated.
As a method of providing a charge removal member, for example, as shown in FIG. 12, a method of providing a charge removal brush 67 on the downstream side of the development region of the development roll 64 and scraping off the residual toner on the development roll 64 while removing the charge is known. However, depending on how the static elimination brush 67 is applied, the stress applied to the toner increases. In the figure, reference numeral 61 is a toner hopper for containing toner, reference numeral 62 is an agitator for stirring the toner in the toner hopper 61, reference numeral 63 is a toner supply roll for supplying toner to the developing roll 64, and reference numeral 65 is on the developing roll 64. Reference numeral 66 denotes a photoconductor on which an electrostatic latent image is carried.

  Therefore, a method of improving the image performance by separating the charge removal member from the developing roll 64 during image formation (see, for example, Patent Document 1), or a thin plate member 68 as a charge removal member as shown in FIG. By applying a voltage such that the sign of (Va−Vd) is the same polarity as the charging polarity of the toner as the power supply voltages Va and Vd applied to the developing roll 64 and the thin plate member 68, A method for improving the peeling performance of the residual toner (for example, see Patent Document 2) has been proposed. Furthermore, as shown in FIG. 14, a method is proposed in which a static elimination roll 69 is used as the static elimination member, and the contact pressure with the developing roll 64 is smaller than the contact pressure with the toner supply roll 63 (see, for example, Patent Document 3). Has been. In the figure, reference numeral 65a denotes a charging roll for controlling the charging of the toner whose layer thickness is regulated by the layer regulating member 65.

However, as a result of intensive studies on the method including such a charge removal member, the present inventors have found the following problems.
In the static elimination system as described above, the residual toner on the developing roll is not uniformly neutralized, and the uniformity of the newly supplied toner on the developing roll is insufficient, or the toner is peeled off from the developing roll. Since the toner charge amount remains, a phenomenon such as the tendency of the toner to agglomerate with other toners appears particularly when the toner is returned to the toner hopper.
In such a system in which the charge-removing member such as a rotating member or a thin plate-shaped member is brought into contact with the developing roll to remove the residual toner on the developing roll, the charge-removing member is usually made of metal or carbon black. This is because a static elimination electric field applied between the static elimination member and the developing roll is not uniformly applied to the residual toner. As a result, uniform charge removal is not performed over the entire residual toner, or abnormal discharge occurs between the two depending on the bias condition applied between the charge removal member and the developing roll and the installation conditions of both. As a result, the toner adheres to the developing roll and the charge removal member due to abnormal discharge. Therefore, it is important how to provide a uniform static elimination action at the time of static elimination.

  The present invention has been made in order to solve the above technical problems. The developer charging amount and the developer amount on the developer carrying member are made uniform, and the developer charging is performed even when used for a long time. It is an object of the present invention to provide a developing device in which the change in the amount and the developer amount is small, and further, the flowability of the developer in the apparatus is stable, and an image forming apparatus using the developing device.

  That is, as shown in FIG. 1, the developing device according to the present invention has a developer carrying body 2 that faces the image carrying body 1 on which an electrostatic latent image is carried and is rotatable and carries a developer on the surface. The image carrier 1 and the developer carrier 2 are disposed at a position facing the developer carrier 2 on the upstream side in the developer transport direction from the facing portion of the developer carrier 2 and supply the developer to the developer carrier 2. The developer supply member 3 and the image carrier 1 and the developer carrier 2 are opposed to the developer carrier 2 on the downstream side in the developer conveyance direction and upstream of the developer supply member 3. A neutralizing member 4 disposed at the opposite position and for neutralizing the residual developer on the developer carrier 2, and at least the surface facing the developer carrier 2 is ion-conductive as a conductive agent. Composed of the semiconductive resin layer 4a containing only the conductive material 8 And it features.

Further, as a typical aspect of the present invention, a rotatable cylindrical thin film member facing the image carrier 1 on which an electrostatic latent image is carried is provided, and a developer is carried on the surface of the cylindrical thin film member. A developer carrier 2 to be conveyed, a developer supply member 3 that is disposed opposite to the developer carrier 2 and supplies the developer to the developer carrier 2, and an image carrier 1 and a developer carrier 2 Disposed on the downstream side of the developer conveyance direction from the facing portion and upstream of the developer supply member 3 at a position facing the developer carrier 2 and discharges residual developer on the developer carrier 2. The neutralization member 4 is provided, and the neutralization member 4 includes at least a surface facing the developer carrying member 2 constituted by a semiconductive resin layer 4a containing only an ion conductive material as a conductive agent.
As a typical embodiment, if the surface of the cylindrical thin film member is constituted by the semiconductive resin layer 4a containing only an ion conductive material as a conductive agent, the bias condition at the time of static elimination is further stabilized, and the static elimination is performed. It is preferable because the performance is further improved.

In such technical means, the developing device according to the present invention uses a one-component developer, and the developer may be either magnetic or non-magnetic.
The developer carrier 2 may be in the form of a roll or a belt as long as it can carry the developer. From the viewpoint of effective development, the developer carrier 2 is placed in contact with the image carrier 1. Although the embodiment is preferable, the image carrier 1 may be arranged in a non-contact manner. Further, the developer carrier 2 may be an elastic body or a rigid body.
Furthermore, the developer supply member 3 may be either in contact with or not in contact with the developer carrier 2, and any material can be used as long as it can supply the developer to the developer carrier 2. Absent.

The neutralization member 4 according to the present invention may be in contact with or non-contact with the developer carrier 2 as long as the developer on the developer carrier 2 can be neutralized. The residual developer after development on the developer carrier 2 can be effectively neutralized, the residual developer on the developer carrier 2 can be easily removed, and the occurrence of development history can be suppressed. Can do.
Further, the neutralization member 4 preferably includes a neutralization bias applying means 5 for applying a neutralization bias for neutralizing the residual developer on the developer carrier 2 with the developer carrier 2. As a result, the charge removal action of the residual developer on the developer carrier 2 can be promoted.
Further, it is preferable to supply the static elimination bias by direct current constant current control because a stable and uniform static elimination bias can be applied. Further, it is preferable to superimpose an AC bias on a DC bias as a discharging bias, so that the residual developer attached on the developer carrier 2 can be more effectively discharged.

  As a typical aspect of the static elimination member 4 in this invention, the aspect which laminated | stacked the semiconductive resin layer 4a on the electroconductive plate-shaped base material, the aspect which laminated | stacked the semiconductive resin layer 4a on the electroconductive rotary body surface, electroconductivity The aspect which provided the brush-like member comprised by the fibrous form as the semiconductive resin layer 4a on the surface of a flexible rotator is mentioned.

And as semiconductive resin layer 4a containing the ion conductive substance in this invention, it is comprised by the layer of a volume resistivity of 10 < ⁸ > -10 < ¹² > (omega | ohm) * cm, More preferably, 10 < ⁹ > -10 < ¹¹ > (omega | ohm) * cm. If it is. If the volume resistivity of the semiconductive resin layer 4a is smaller than 10 ⁸ Ω · cm, the discharge current at the time of charge removal is not sufficiently secured, and the charge removal action on the developer becomes insufficient. On the other hand, if the volume resistivity is larger than 10 ¹² Ω · cm, the discharge is not performed and the developer is not discharged.

Here, the difference between the ion conductive material as the conductive agent and the electron conductive material will be described. 2A and 2B are schematic views showing a cross section of the semiconductive resin layer 4a according to the present invention. FIG. 2A shows a state in which the ion conductive material 8 is dispersed in the resin 7. b) shows a state in which an electron conductive substance 9 such as carbon black is dispersed in the resin 7.
Unlike the electron conductive material 9, the ion conductive material 8 is excellent in dispersibility in the resin 7 (basically, it is dispersed at the molecular level), and thus is easily uniformly dispersed in the resin 7. When an electric field is applied to the layer 4a, the current path in the resin 7 is uniform, there is no particularly weak point, and a uniform current flows over the entire semiconductive resin layer 4a.

On the other hand, when the electron conductive substance 9 is dispersed in the resin 7, there is also a particle size of the electron conductive substance 9, and cluster-like lumps are formed at various places. For this reason, when an electric field is applied to the semiconductive resin layer 4a, a portion having weak electric resistance characteristics (for example, a chain-like portion of particles as indicated by an arrow in the figure) is formed, and a concentrated current flows. A uniform current cannot flow through the entire resin layer 4a. Further, when the electron conductive substance 9 is used, for example, when the carbon black is used and when the metal fine particles are used, the environment change direction of the resistance value differs depending on the substance used. That is, for example, since carbon black has semiconducting properties, the temperature coefficient of resistance is negative, whereas metal or the like has a positive temperature coefficient of resistance.
Therefore, when the semiconductive resin layer 4a is used for electric field control (current control), it is possible to maintain stable conditions by dispersing the ion conductive material 8 in the resin 7.
Examples of the ion conductive substance 8 include perchlorates (for example, lithium perchlorate, sodium perchlorate, ammonium perchlorate, etc.) and quaternary ammonium salts. Examples of the resin 7 include urethane and acrylic. And resins such as nylon and polyvinylidene fluoride.

  Furthermore, in the present invention, as shown in FIG. 1, the developer carrier 2 is disposed opposite to the developer carrier 2 on the downstream side of the developer carrier 2 in the developer transport direction and the developer carrier 2. It is preferable to include a charge regulating member 6 that regulates the layer of the developer above, whereby a stable charge amount and a developer amount can be added to the developer on the developer carrier 2, and the developer It becomes possible to make the charge amount of the developer remaining on the carrier 2 uniform. Therefore, the static elimination performance by the static elimination member 4 can be further stabilized.

Further, in the developing device according to the representative aspect of the present invention, it is preferable to include a drive transmission means for transmitting the driving force of the charge regulating member 6 to the developer carrier 2 which is a cylindrical thin film member. In this case, the relationship (rotation direction, rotation state, etc.) between the developer carrier 2 and the developer supply member 3 can be freely set, and the appropriateness of the developer from the developer supply member 3 to the developer carrier 2 can be set. Supply performance can be ensured.
The drive transmission means includes a drive pressing member that is positioned at both ends of the cylindrical thin film member with the rotation shaft of the charge regulating member 6 as a core and is pressed against the cylindrical thin film member, and an inner peripheral surface side of the cylindrical thin film member. And a supporting member that sandwiches the cylindrical thin film member together with the driving pressing member. As a typical aspect, the driving pressing member (roller member or the like) is a developer with the rotation axis of the charging regulating member 6 as an axis. The aspect provided in the both ends of the support body 2 is mentioned.

Furthermore, in the developing device of this representative aspect, it is preferable that the cylindrical thin film member includes a holding member that holds the shape of the cylindrical thin film member. As a result, the developer carrying member 2 can be secured with good development characteristics.
The present invention is also directed to an image forming apparatus including the developing device described above.

  According to the present invention, the neutralization member that neutralizes the residual developer on the developer carrier after development is provided at a position facing the developer carrier, and the neutralization member has at least a surface facing the developer carrier. Is made up of a semiconductive resin layer containing only an ion conductive material as a conductive agent, so that it is possible to perform a uniform static elimination action on the residual developer, prevent development history, and collect the developed The charge amount of the agent can also be reduced. For this reason, the developer charge amount and developer amount on the developer carrying member are made uniform, and the change in developer charge amount and developer amount is small even when used for a long time. A developing device having stable fluidity can be provided.

Further, as a representative aspect of the present invention, a static charge is removed by using a cylindrical thin film member for the developer carrying member, and removing the residual developer on the developer carrying member after development at a position facing the developer carrying member. In addition to the basic effects described above, if the discharging member has at least a surface facing the developer carrying member and is composed of a semiconductive resin layer containing only an ion conductive material as a conductive agent, The driving conditions of the developer carrier and the developer supply member can be freely set, and the developer can be supplied more stably.
Furthermore, by using these developing devices, it is possible to provide an image forming apparatus capable of stable image formation over a long period of time.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 3 schematically shows the image forming apparatus according to the first embodiment to which the present invention is applied.
In the figure, reference numeral 21 denotes a photoconductor carrying an electrostatic latent image made up of an organic photoconductor rotating in the direction of the arrow. The photoconductor 21 is charged by a charging device 22 such as a charging roll, and laser writing is performed. An electrostatic latent image is written by an exposure device 23 having an apparatus and an LED array. The electrostatic latent image is formed as a potential image based on the contrast with the high potential portion not exposed to light because the surface potential of the photosensitive member 21 exposed to light decreases.
Further, the developing device 30 accommodates toner, which is a non-magnetic one-component developer, in a developing housing 31 and carries the toner on a developing roll 32 as a developer carrying member. By applying the developing bias, the developing roll 32 is held at an intermediate potential between the high potential portion and the low potential portion of the electrostatic latent image, and the image portion of the electrostatic latent image is developed with the charged toner. It is a thing. Reference numeral 34 denotes a toner supply roll that supplies toner to the developing roll 32.

Further, the transfer device 26 is constituted by, for example, a transfer roll disposed in contact with the photoconductor 21, and applies a transfer bias in a direction in which a toner image on the photoconductor 21 is attracted by a bias power source 27, thereby causing the photoconductor 21 to be attracted. The upper toner image is transferred to the recording material 28.
The toner remaining on the photoreceptor 21 is removed by, for example, a doctor blade type cleaning device 29.
Further, in the present embodiment, the recording material 28 onto which the toner image on the photosensitive member 21 has been transferred is conveyed to the fixing device 50, and the toner image is fixed on the recording material 28 by the fixing device 50.
The fixing device 50 has, for example, a heat roll method, and includes a heating roll 51 and a pressure roll 52. By passing the recording material 28 between the heating roll 51 and the pressure roll 52, the toner image is recorded. 28 is fixed.

Here, the developing device 30 which is a characteristic point of the present embodiment will be described in detail with reference to FIG. In the drawing, the developing device 30 has a developing housing 31 that opens toward the photosensitive member 21, and a developing roll 32 is provided at a position facing the opening of the developing housing 31 and facing the photosensitive member 21. It is housed in a rotatable manner.
The developing roll 32 in the present embodiment has a configuration in which a cylindrical semiconductive rubber made of a synthetic rubber such as urethane rubber or silicone rubber is coated on the peripheral surface of a metal shaft such as stainless steel, and both ends of the shaft are illustrated. The outer support is rotatably supported. The developing roll 32 is connected to a bias power source 33 at the end of the shaft so that a predetermined developing bias is applied. In the present embodiment, the developing roll 32 has a configuration in which a metal shaft is covered with semiconductive rubber, but a metal roll such as aluminum or stainless steel may be used. Further, although the developing roll 32 and the photosensitive member 21 are in contact with each other, they may be non-contact.

  Behind the developing roll 32, a toner supply roll 34 that contacts the developing roll 32 and supplies toner to the developing roll 32 is disposed. The toner supply roll 34 in the present embodiment has a configuration in which a metal shaft such as stainless steel is covered with semiconductive foamed urethane, and, like the developing roll 32, both ends of the shaft rotate to a support body not shown. It is supported freely. A bias power supply 41 is connected to the end of the shaft so that a supply bias for supplying toner from the toner supply roll 34 to the developing roll 32 side is applied. Then, the toner supply roll 34 is maintained so as to rotate in a predetermined amount (0.5 mm in the present embodiment) with respect to the developing roll 32, and the toner supply from the toner supply roll 34 to the developing roll 32 is maintained. It is designed to be performed stably. It should be noted that this amount of biting is preferably as small as possible within a range where stable toner supply is possible from the viewpoint of extending the life of the developing roll 32 and the toner supply roll 34.

  A toner hopper 35 that contains toner is provided behind the toner supply roll 34, and the toner is agitated by the rotation of the agitator 36. The agitator 36 has a structure in which a blade 36b of a resin film such as a polyester film is supported on a plastic shaft 36a, and the toner in the toner hopper 35 is rotated by the rotation of the shaft 36a during the developing operation. In addition, the toner is supplied to the toner supply roll 34 side.

Further, in the present embodiment, the toner charge amount and the toner amount are regulated with respect to the toner layer on the developing roll 32 on the downstream side in the rotation direction of the developing roll 32 from the facing portion of the developing roll 32 and the toner supply roll 34. A regulating blade 37 is disposed. The regulating blade 37 has a configuration in which a thin plate-like urethane rubber is attached to the side of the thin metal plate facing the developing roll 32, and one end of the thin metal plate is fixed to the developing housing 31.
Therefore, a toner layer in which the toner charge amount and the toner amount are appropriately regulated is formed on the developing roll 32 by the regulating blade 37, and the developing region which is a portion where the photosensitive member 21 and the developing roll 32 are opposed to each other. In this way, stable development is performed.
In the present embodiment, the toner charge amount and the toner amount are regulated by the regulating blade 37. However, the present invention is not limited to this. For example, the thickness of the toner layer on the developing roll 32 on the toner supply roll 34 side in advance. When the regulation is performed, the regulation blade 37 may be formed in a roll shape so that only the toner charge amount is regulated.

In particular, in the present embodiment, a neutralizing member 38 that neutralizes residual toner that is not used for development and remains on the developing roll 32 is located at a position facing the developing roll 32 downstream of the developing region in the toner conveyance direction. Is provided.
As shown in FIG. 5, the static elimination member 38 in the present embodiment is provided with a thin plate-like conductive electrode 38b on a plastic substrate 38a, and further in PVDF (polyvinylidene fluoride) on the conductive electrode 38b. And a semiconductive resin layer 38c in which an ion conductive material is dispersed. The semiconductive resin layer 38c is adjusted so that the volume resistivity is 10 ¹⁰ Ω · cm.
In this embodiment, when negatively charged toner is used, constant current control is performed so that the conductive electrode 38b of the charge removal member 38 is on the positive electrode side with respect to the developing roll 32, and an alternating electric field is superimposed. Further, the charge of the residual toner on the developing roll 32 can be made uncharged by supplying the neutralizing bias by the bias power source 42. The static elimination bias applied at this time is preferably controlled to be equal to or higher than the discharge start voltage between the static elimination member 38 and the developing roll 32. If the static elimination bias is equal to or lower than the discharge start voltage, it is sufficient. In other words, the development history can be eliminated (leading to ghost elimination).

Next, the operation of the developing device 30 according to the present embodiment will be described with reference to FIG.
In the figure, the toner agitated by the agitator 36 in the toner hopper 35 is supplied to the toner supply roll 34 side by the rotation of the blade 36 b of the agitator 36. The toner carried on the toner supply roll 34 is conveyed along with the rotation of the toner supply roll 34 and reaches a portion facing the developing roll 32. At this time, the toner on the toner supply roll 34 is supplied to the developing roll 32 side due to the mechanical rubbing force between the developing roll 32 and the toner supply roll 34 at the opposite portion and the electric field effect of the supply bias by the bias power supply 41. As a result, a toner layer controlled to some extent is formed on the developing roll 32.
The toner supplied to the developing roll 32 is layer-regulated by the regulating blade 37, and a toner thin layer having a predetermined toner charge amount and a predetermined toner amount is formed on the developing roll 32. For this reason, the toner thin layer whose layer is regulated on the developing roll 32 is conveyed to the developing area between the developing roll 32 and the photoreceptor 21.
In the development area, development is performed by the development bias from the bias power source 33, and the electrostatic latent image on the photoconductor 21 is visualized. Further, the residual toner that remains without being developed on the developing roll 32 is conveyed on the developing roll 32 as it is.

In the development area, toner is consumed according to the electrostatic latent image on the photoconductor 21, so that the residual toner on the developing roll 32 is in a state (development history) with a different toner layer thickness according to the electrostatic latent image. It has become. For this reason, if the residual toner is introduced into the facing portion (nip region) between the developing roll 32 and the toner supply roll 34, the non-uniformity of the toner on the developing roll 32 cannot be completely removed. Therefore, not only the toner amount but also the charge amount becomes non-uniform on the developing roll 32 to which toner is newly supplied.
In the present embodiment, in order to prevent such a situation, the charge removal member 38 in which the semiconductive resin layer 38c (see FIG. 5) including the ion conductive material is formed on the residual toner on the developing roll 32 is used. As a result, a uniform charge removal bias is applied to the residual toner, and the charge removal is performed uniformly over the entire axial direction of the developing roll 32. The discharged residual toner is easily scraped off at the nip region between the developing roll 32 and the toner supply roll 34, and the toner newly supplied to the developing roll 32 is made uniform. At this time, since the scraping is easy, the stress on the toner is reduced and the development history can be suppressed. In the present embodiment, a part of the residual toner acts due to the neutralizing member 38 due to the mechanical scraping action. However, even if there is no mechanical scraping action, the developing roller 32 is not affected. Uniformity of the supplied toner is achieved.
Further, since the residual toner on the developing roll 32 is discharged, the toner scraped off from the developing roll 32 is sufficiently discharged, and this is collected in the toner hopper 35. Therefore, unnecessary charging of the toner in the toner hopper 35 is performed. And the agglomeration can be prevented, the fluidity and agglomeration of the toner supplied from the toner hopper 35 to the toner supply roll 34 can be stabilized, and the uniformity of the toner supplied onto the developing roll 32 can be further stabilized. .

  As described above, in this embodiment, an ion conductive material is used. However, if an electron conductive material such as carbon black is used, electric field concentration occurs in some particle chains, and discharge is not generated. It becomes uniform. As a result, the uniform charge eliminating effect on the residual toner does not work, and the development history cannot be eliminated. In addition, there is a secondary influence such as discharge traces due to abnormal discharge.

  Further, in the present embodiment, a plate-like member (see FIG. 6A) is used as the charge removal member 38, but the shape of the charge removal member 38 is not limited to this, and for example, FIGS. 6B and 6C. As shown in FIG. 4, a roll member or a brush-like rotating member may be used. At this time, a semiconductive resin layer containing an ion conductive material is formed on at least the surface of the roll member, and a semiconductive resin containing an ion conductive material is brushed on the brush-like rotating member. What is necessary is just to be formed in the shape.

  Furthermore, in this embodiment, as shown in FIG. 4, a rubber roll is used as the developing roll 32 and a foam roll is used as the toner supply roll 34. However, the present invention is not limited to this, and for example, a metal shaft itself is used as the developing roll 32. A surface having an insulating thin film or a semiconductive thin film formed on the surface may be used. In this case, the photosensitive member 21 may be provided with a predetermined gap. Further, as the toner supply roll 34, it is also possible to use a metal shaft made of stainless steel, aluminum, or the like, a metal rigid roll made of a cylindrical member, or a rigid roll whose surface is coated with a resin. May be spaced apart. Note that the toner supply roll 34 is in the above-described mode, and the developing roll 32 is configured by an elastic body or a flexible member.

Embodiment 2
FIG. 7 shows a main part of a developing device according to Embodiment 2 of the image forming apparatus to which the present invention is applied. In this figure, the present embodiment is configured in substantially the same manner as the developing device 30 in the first embodiment, but the point where the static elimination member 38 is configured by a roll member and the thickness of the toner layer on the developing roll 32 are regulated. The point from which the layer control roll 39 is arrange | positioned instead of a control blade differs from Embodiment 1. FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and the detailed description is abbreviate | omitted.

  The static elimination member 38 in the present embodiment is formed by forming an elastic layer such as conductive urethane rubber on the surface of the metal roll, and further covering the surface with a PVDF flexible tube (seamless tube) containing an ion conductive material. It becomes the composition. Further, in the present embodiment, the static elimination member 38 is disposed in a state of biting into the developing roll 32 with a predetermined biting amount (0.1 mm in the present embodiment), and a predetermined static elimination bias is applied by the bias power source 42. In addition to being applied, the follower rotates as the developing roll 32 rotates.

  Further, the layer regulating roll 39 has a configuration in which a metal shaft peripheral surface such as stainless steel is coated with a semiconductive rubber such as urethane rubber, and rotates in the Against direction with respect to the developing roll 32 (at a portion facing each other). And is maintained in a state where it is bitten into the developing roll 32 by a predetermined amount (0.5 mm in this embodiment). In addition, a bias power source (not shown) is connected to the shaft of the layer regulating roll 39, and a charging bias for applying an effective charge amount to the toner layer on the developing roll 32 at a portion facing the developing roll 32 is provided. It is to be applied. Therefore, a toner layer in which the toner charge amount and the toner amount are appropriately regulated is formed on the developing roll 32 by the layer regulating roll 39, and development that is a portion opposite to the photoreceptor 21 and the developing roll 32 is performed. Stable development is performed in the area.

Furthermore, in this embodiment, a scraping member 40 that scrapes off the toner remaining on the layer regulating roll 39 is provided with one end fixed to the developing housing 31.
The scraping member 40 in the present embodiment is arranged so that a thin plate-like urethane rubber is in a doctor direction with respect to the rotation direction of the layer regulating roll 39 so as to scrape off the toner adhered on the layer regulating roll 39. It has become. The scraping member 40 is not limited to urethane rubber, and may be composed of other plastic materials or metal materials.

Also in this embodiment, the residual toner on the developing roll 32 after the developing area can be discharged efficiently and uniformly, and a uniform toner layer is not affected by the development history when the toner is supplied by the toner supply roll 34. It is formed on the developing roll 32. Further, since it is not necessary to strongly press the toner supply roll 34 against the developing roll 32, the stress on the toner is small, and it is possible to prevent the toner from sticking.
Further, in the present embodiment, since a rotating body is used as the static elimination member 38, the life can be normally extended as compared with the first embodiment using a plate-like member. If the toner adhering to the surface layer of the rotating body is scraped off, the service life can be further extended.

  In the present embodiment, the mode in which the static elimination member 38 is driven and rotated by the developing roll 32 is shown. However, the present invention is not limited to this. Moreover, when providing a speed difference, the rotation direction of the static elimination member 38 does not interfere.

Embodiment 3
FIG. 8 shows an outline of an image forming apparatus provided with the developing device 30 according to the third embodiment to which the present invention is applied. In this figure, the present embodiment is configured in substantially the same manner as the image forming apparatus (see FIG. 3) in the first and second embodiments, but the rotation direction of the photoconductor 21 is different, and the developing device 30 will be described later. Thus, the different points are different from the first and second embodiments. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, 2, and the detailed description is abbreviate | omitted.

The developing device 30 in the present embodiment is configured as shown in FIG. In this figure, the present embodiment is provided with a layer regulating roll 39 and a roll member static eliminating member 38, as in the developing device 30 (see FIG. 7) of the second embodiment, but the rotation direction of the developing roll 32 is implemented. Therefore, the layer regulating roll 39 is disposed below the developing roll 32.
Further, a scraping member 40 that scrapes off the toner adhering to the layer regulation roll 39 is disposed opposite to the layer regulation roll 39, and is further disposed opposite to the layer regulation roll 39. A neutralizing roll 43 is provided for neutralizing the toner adhering to the layer regulating roll 39.

Further, in the present embodiment, the developing roll 32 and the toner supply roll 34 are arranged with a predetermined gap, and are rotated in the same direction (with direction) at the opposed portions thereof. For this reason, the toner supplied from the toner supply roll 34 is jetted downward after passing through this facing portion (nip region) except for the amount supplied to the developing roll 32. In the present embodiment, a second agitator 44 for returning the ejected toner to the toner hopper 35 is disposed below the toner supply roll 34.
The second agitator 44 is provided with, for example, a plurality of (four in this example) semiconductive films around a conductive resin shaft, and the second agitator 44 rotates to lower toner. Is returned to the toner hopper 35 side.

The operation of the developing device 30 in the present embodiment will be described focusing on differences from the developing device 30 (see FIG. 7) of the second embodiment.
In the present embodiment, since the developing roll 32 and the toner supply roll 34 are spaced apart from each other, the properties of the toner supplied from the toner hopper 35 to the toner supply roll 34 have a great influence on the toner layer on the developing roll 32. Become.
That is, in the toner hopper 35, the toner is affected by the fluidity and aggregation state of the toner, and the mixture of the toner charged to the normal polarity (the polarity that the toner originally has by CCA (charge control agent) or the like) and the toner charged to the opposite polarity increases. Come. Further, when the toner supplied from the toner hopper 35 to the toner supply roll 34 is supplied to the development roll 32, due to the potential difference between the development bias 33 by the bias power supply 33 and the supply bias by the bias power supply 41, the toner is supplied to the development roll 32 side. Toner supply is promoted. Therefore, if the charged state and fluidity of the toner supplied from the toner supply roll 34 to the developing roll 32 are non-uniform, the toner supplied onto the developing roll 32 tends to be non-uniform.
In addition, toner particles tend to aggregate due to the presence of reverse polarity toner or toner having a non-uniform charge amount. Therefore, even when the gap between the toner supply roll 34 and the developing roll 32 is adjusted and a uniform electric field is supplied to the developing roll 32 by applying a constant electric field, the formed toner layer becomes non-uniform. End up.

In the present embodiment, the charge of the toner collected from the layer regulating roll 39 is removed by providing the layer regulating roll 39 with the charge removing roll 43, so that the toner collected to the toner hopper 35 is discharged. become. Further, in the present embodiment, if the second agitator 44 is neutralized, the toner ejected from the nip region between the developing roll 32 and the toner supply roll 34 is surely neutralized and transferred to the toner hopper 35. Thus, the toner can be stably supplied to the developing roll 32 even during long-term use.
In the present embodiment, the static eliminating roll 43 is used. However, instead of the static eliminating roll 43, for example, a brush-like rotating member may be used, or a charger such as a corotron may be used.

Embodiment 4
FIG. 10 shows a main part of the developing device 30 according to the fourth embodiment of the image forming apparatus to which the present invention is applied. In this figure, the present embodiment is configured in substantially the same manner as the developing device 30 (see FIG. 9) in the third embodiment, but the configuration of the developing roll 32 and the layer regulating roll 39 are not provided with the charge eliminating roll 43. The point is different. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 3, and the detailed description is abbreviate | omitted.

The developing roll 32 in the present embodiment includes a sliding member 47 that holds the shape of the flexible tube 46 and has conductivity in a flexible tube 46 of PVDF having a thickness of 100 μm. It has a configuration.
Here, the pressure contact state between the developing roll 32 and the layer regulating roll 39 will be described. FIG. 11 shows the pressure contact state between the two. A ring-shaped support member 48 that presses the flexible tube 46 from the inner surface is provided inside both ends of the flexible tube 46. Further, the sliding member 47 is provided with a concave portion (A portion in the figure) at a position where the sliding member 47 faces the layer regulating roll 39, so that the flexible tube 46 of the developing roll 32 and the layer regulating roll 39 are stable. A space in which the flexible tube 46 can be deformed is taken so that sufficient pressure contact is ensured. Therefore, the contact state between the developing roll 32 and the layer regulating roll 39 can be kept more stable.
Further, a pressing member 45 such as a rubber roller member is attached to both ends 39 a of the layer regulating roll 39 at positions facing the support member 48 and the flexible tube 46. In the present embodiment, the flexible member 46 is rotated by the pressing member 45 rotating as the layer regulating roll 39 rotates.

  In the present embodiment, as shown in FIG. 10, the slide member 47 is also provided with a concave portion (B portion in the figure) at a position facing the photoconductor 21, and the flexible tube 46 of the developing roll 32. A space where the flexible tube 46 can be deformed is taken so that a stable contact state between the flexible tube 46 and the photosensitive member 21 is sufficiently secured. Therefore, the contact state between the developing roll 32 and the photoreceptor 21 can be further stabilized.

Next, the operation of the developing device 30 in the present embodiment will be described, particularly regarding the relationship of the developing roll 32.
In this embodiment, since the flexible tube 46 of the developing roll 32 is driven from the driving force of the layer regulating roll 39, the rotation direction, speed, etc. of the developing roll 32 and the toner supply roll 34 are improved in terms of toner supply performance. Conditions can be set so that priority is given, and toner supply to the developing roll 32 can be further stabilized. Further, since the flexible tube 46 of the developing roll 32 is rotated by the pressing members 45 attached to both end portions 39a of the layer regulating roll 39, the rotation of the flexible tube 46 is stabilized and the drive transmission is performed. For example, a gear or the like is not required, and cost increase can be suppressed and downsizing of the apparatus can be promoted.

Furthermore, in the present embodiment, the flexible tube 46 is driven at the position facing the layer regulating roll 39, so that the flexible tube 46 is pushed toward the photoreceptor 21. Therefore, even if the sliding member 47 is not provided with a concave portion (B portion in the figure), the sliding member included in the flexible tube 46 of the developing roll 32 is provided at the portion facing the developing roll 32 and the photosensitive member 21. It is easy to create a gap between the moving member 47 and low contact pressure development with a lower contact pressure between the flexible tube 46 and the photoreceptor 21 can be realized.
Furthermore, since the flexible tube 46 is rotated by the pressing member 45, the flexible tube 46 is pressed against the sliding member 47 between the flexible tube 46 and the toner supply roll 34. The gap between them is stabilized. For this reason, the stress applied to the toner is small and constant, and a stable image quality is maintained over a long period of time.
In the present exemplary embodiment, the developing roll 32 and the toner supply roll 34 are separated from each other. However, the present invention is not limited to this, and the developing roll 32 and the toner supply roll 34 may be in contact with each other.

It is explanatory drawing which shows the outline | summary of the image development apparatus concerning this invention. (A) (b) is explanatory drawing which shows the effect | action of the semiconductive resin layer based on this invention. 1 is an explanatory diagram showing Embodiment 1 of an image forming apparatus to which the present invention is applied. FIG. 2 is an explanatory diagram illustrating a developing device according to the first embodiment. FIG. 3 is an explanatory diagram illustrating a static elimination member according to the first embodiment. (A)-(c) is explanatory drawing which shows the aspect of the static elimination member of Embodiment 1. FIG. FIG. 10 is an explanatory diagram illustrating a developing device according to a second embodiment. 6 is an explanatory diagram illustrating an image forming apparatus according to Embodiment 3. FIG. FIG. 10 is an explanatory diagram illustrating a developing device according to a third embodiment. FIG. 10 is an explanatory diagram illustrating a developing device according to a fourth embodiment. FIG. 10 is an explanatory diagram showing a relationship between a developing roll and a layer regulating roll in Embodiment 4. It is explanatory drawing which shows the developing device as a conventional typical example. It is explanatory drawing which shows the image development apparatus as a 2nd prior art example. It is explanatory drawing which shows the image development apparatus as a 3rd prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Developer carrier, 3 ... Developer supply member, 4 ... Static elimination member, 4a ... Semiconductive resin layer, 5 ... Static elimination bias application means, 6 ... Charge control member, 8 ... Ion conduction Sex substances

Claims (12)

A developer carrying member that is rotatable and opposed to an image carrier on which an electrostatic latent image is carried;
A developer supply member that is disposed at a position facing the developer carrying member on the upstream side in the developer conveying direction from a facing portion between the image carrying member and the developer carrying member and supplies the developer to the developer carrying member. When,
The developer carrying member is disposed at a position facing the developer carrying member on the downstream side in the developer conveying direction from the facing portion between the image carrying member and the developer carrying member and upstream from the developer supplying member. A charge removing member for discharging the residual developer on the top,
This developing device is characterized in that at least the surface facing the developer carrying member is constituted by a semiconductive resin layer containing only an ion conductive material as a conductive agent. A developer carrier having a rotatable cylindrical thin film member facing an image carrier on which an electrostatic latent image is carried, and carrying and transporting the developer to the surface of the cylindrical thin film member;
A developer supply member disposed opposite to the developer carrier and supplying the developer to the developer carrier;
An image carrier and a developer carrier are disposed at a position facing the developer carrier on the downstream side of the developer conveyance direction and upstream of the developer supply member from the facing portion of the developer carrier and on the developer carrier. A static elimination member that neutralizes the residual developer of
This developing device is characterized in that at least the surface facing the developer carrying member is constituted by a semiconductive resin layer containing only an ion conductive material as a conductive agent. The developing device according to claim 2, wherein
Further, the developing device characterized in that the surface of the cylindrical thin film member is constituted by a semiconductive resin layer containing only an ion conductive material as a conductive agent. The developing device according to claim 1 or 2,
The developing device characterized in that the semiconductive resin layer has a volume resistivity of 10 ⁸ Ω · cm to 10 ¹² Ω · cm. The developing device according to claim 1 or 2,
A developing device characterized in that the neutralizing member includes a neutralizing bias applying means for applying a neutralizing bias between the developer carrying member and a residual developer on the developer carrying member. The developing device according to claim 5, wherein
The developing device according to claim 1, wherein the static elimination bias is supplied by direct current constant current control. The developing device according to claim 5, wherein
The developing device according to claim 1, wherein the neutralizing bias is obtained by superimposing an alternating current component on a direct current component. The developing device according to claim 1 or 2,
Furthermore, a charge regulating member is provided opposite to the developer carrying member on the downstream side in the developer transport direction of the developer carrying member from the developer supplying member and controls the layer of the developer on the developer carrying member. A developing device. In the developing device according to claim 8, in a mode in which the developer carrying member is a cylindrical thin film member,
A developing device comprising drive transmission means for transmitting the driving force of the charge regulating member to the developer carrying member. The developing device according to claim 9, wherein
The drive transmission means is located at both ends of the cylindrical thin film member with the rotation shaft of the charge regulating member as a core material and is pressed against the cylindrical thin film member; and
A developing device comprising: a support member provided on an inner peripheral surface side of the cylindrical thin film member and sandwiching the cylindrical thin film member together with the drive pressing member. The developing device according to claim 2, wherein
The cylindrical thin film member includes a holding member that holds the shape of the cylindrical thin film member. An image carrier on which an electrostatic latent image is carried;
An image forming apparatus comprising: the developing device according to claim 1, which develops an electrostatic latent image on the image carrier.

Images