JP5455022B2 - Developing device, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention includes a plurality of types of electrode members to which different voltages are applied, and conveys the developer to the image area by a developer carrier that causes the developer carried on the outer peripheral surface to fly by the action of an electric field. The present invention relates to a developing device that performs development, an image forming apparatus including the same, and a process cartridge.

2. Description of the Related Art Conventionally, a developing device having a developer carrying member provided with a plurality of electrode members to which different voltages are applied is known.
As such a developing device, for example, the developer on the developer carrying member is not brought into direct contact with the latent image carrier such as a photosensitive member, but the developer is supplied to the latent image on the latent image carrying member for development. There is a developing device to perform. As an example of this developing device, there is one that employs a system in which toner is supplied onto a latent image carrier by making a one-component developer (toner) on the developer carrier into a cloud (Patent Document 1). -Patent Document 6). In the developer carrier used in this method, a plurality of types of electrode members are arranged at a predetermined pitch along the outer peripheral surface, and the outer peripheral surface side of the plurality of types of electrode members is covered with a protective layer. When different voltages that change with time are applied to the plurality of types of electrode members, and a time-changing electric field is formed between the plurality of types of electrode members that are close to each other, the developer carrier is generated by the electric field. The upper toner can be caused to fly between a plurality of types of electrode members that are close to each other (this phenomenon of toner flying is hereinafter referred to as “flare”). As a result, the toner is clouded in a space near the outer peripheral surface of the developer carrier.

In the developing device using the above method, if the electric field formed between the electrode members is too weak, there are the following problems. That is, the force that causes the toner to fly by the electric field cannot overcome the adhesion force between the toner and the outer peripheral surface of the developer carrier, and the toner does not fly from the developer carrier and cannot move onto the photoconductor. A decrease in concentration occurs. On the other hand, when the electric field formed between the electrode members is too strong, there are the following problems. That is, a leak occurs between electrode members that form an electric field to destroy the electrode member, or a leak occurs between the electrode member and a member that is in contact with the outer peripheral surface of the developer carrier, and the outer peripheral surface is more than the electrode member. Damaged surface layer provided on the side.
For this reason, the voltage applied with respect to multiple types of electrode member is set so that the electric field formed between electrode members may become appropriate intensity | strength.

However, even when the voltage applied to the plurality of types of electrode members is the same, the electric field formed between the electrode members depends on the thickness of the surface layer that forms the outermost protective layer of the developer carrier. The intensity is different. For this reason, even if the voltage applied to a plurality of types of electrode members is set so that the electric field has an appropriate strength when the surface layer thickness is a predetermined value, the surface layer thickness is the predetermined value. If the values are different, the electric field formed between the electrode members cannot be set to an appropriate electric field strength.
Since the thickness of the surface layer varies at the time of manufacture, if the setting of the voltage applied to the electrode member is the same in all devices, an appropriate electric field is applied to devices having a surface layer thickness different from the predetermined value. A strong electric field cannot be formed. Even if the voltage applied to multiple types of electrode members is set to form an electric field with an appropriate electric field strength at the initial surface layer thickness for each device, the surface layer will be worn away by long-term use. Therefore, when the applied voltage is constant, an electric field having an appropriate electric field strength cannot be formed during long-term use.
Also, the surface layer characteristics other than the layer thickness have characteristics that make it impossible to form an electric field having an appropriate electric field strength because the values are different. For example, if the volume resistivity value of the material constituting the surface layer, which is a characteristic of the surface layer, is different, even if the thickness of the surface layer and the setting of the voltage applied to the electrode member are the same, it is formed between the electrode members. The electric field strength varies.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device having a developer carrier having a plurality of types of electrode members to which different voltages are applied, and having a surface layer characteristic value. To provide a developing device capable of performing stable development without causing a decrease in image density or damage even if it is not constant, and an image forming apparatus and a process unit including the developing device.

In order to achieve the above object, the invention according to claim 1 is provided with a developer carrier for transporting a developer carried on the outer peripheral surface to a development region, comprising a plurality of types of electrode members to which different voltages are applied. By applying different voltages to the plurality of types of electrode members, an electric field is formed between the different types of electrode members, and the developer flies over the outer peripheral surface of the developer carrier by the electric field. An electric field forming means for forming a latent image on the latent image carrier using a developer flying on an outer peripheral surface of the developer carrier at a facing portion between the developer carrier and the latent image carrier. In the developing device for developing, the developer carrying member is provided with a surface layer characteristic measuring unit provided on the outer peripheral surface side of the plurality of types of electrode members to measure the surface layer characteristic, and the surface layer characteristic measuring unit includes an impedance of the surface layer Surface impedance detection to detect A surface member for detecting the surface impedance of the developer carrying member, the regulating member for regulating the amount of the developer on the outer circumferential surface of the developer carrying member that contacts the outer circumferential surface of the developer carrying member and passes through the contact position; are those wherein that you measure the impedance between said plurality several electrode member and the regulating member.
According to a second aspect of the present invention, in the developing device according to the first aspect, the surface layer characteristic measuring means measures a layer thickness of the surface layer as the characteristic of the surface layer .
Also, the invention of claim 3, in the developing apparatus according to claim 1 or 2, based on the detection result of the surface layer impedance detecting means, so that the electric field formed between the different electrode member becomes constant The above-mentioned electric field forming means is controlled.
According to a fourth aspect of the present invention, in the developing device according to the third aspect , the electric field forming means controls the voltage applied to the plurality of types of electrode members based on the detection result of the surface impedance detecting means. It is characterized by.
The invention according to claim 5 is the developing device according to claim 3 or 4 , further comprising an inter-electrode member impedance measuring means for measuring impedance between different types of electrode members, and a measurement result of the inter-electrode member impedance measuring means. Based on the above, the control of the electric field forming means is corrected.
According to a sixth aspect of the present invention, in the developing device according to any one of the first to fifth aspects, the plurality of types of electrode members are arranged at positions different from each other in the normal direction of the outer peripheral surface, and different types of electrodes are provided. An insulating layer is interposed between the members.
According to a seventh aspect of the present invention, in the developing device of the sixth aspect , the apparatus further comprises an insulating layer impedance detecting means for detecting the impedance of the insulating layer by measuring the impedance between different types of electrode members. It is what.
The invention according to claim 8 provides an image obtained by developing a latent image formed on the latent image carrier by developing the latent image by supplying a developer with a developing device. An image forming apparatus that forms an image on a recording material by transferring the image onto the recording material, wherein the developing device according to any one of claims 1 to 7 is used as the developing device. is there.
According to a ninth aspect of the present invention, a latent image carrier and a developing device for developing a latent image formed on the latent image carrier with a developer are held as a single unit on a common holder. A process cartridge configured to be detachable integrally with an image forming apparatus main body, wherein the developing device according to any one of claims 1 to 7 is used as the developing device. .

  According to the present invention, since the surface layer characteristic measuring means is provided, it is possible to adjust the setting so that the electric field formed between the electrode members has an appropriate intensity according to the measurement result. By performing the above, an excellent effect can be obtained that stable development can be performed without causing a decrease in image density or damage due to leakage.

FIG. 2 is a schematic cross-sectional view illustrating a main part of the printer according to the embodiment. FIG. 4 is an enlarged cross-sectional view of one of four process cartridges provided in the printer. FIG. 3 is a cross-sectional view along the axial direction of a developing device provided in the process cartridge. FIG. 4 is a schematic diagram when the toner carrying roller is viewed from a direction orthogonal to the rotation axis in order to explain the electrode arrangement of the toner carrying roller of the developing device. FIG. 3 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller is cut along a plane orthogonal to a rotation axis thereof. 6 is a graph showing an example of an inner voltage and an outer voltage applied to an inner electrode and an outer electrode of the toner carrying roller, respectively. The graph which shows the outline of the relationship between layer thickness and electric field strength when the layer thickness of a surface layer reduces in the state which does not control an electric field. The graph which shows the outline of the relationship between layer thickness when surface layer thickness changes, and surface layer impedance. The graph which shows the outline of the relationship between the layer thickness of a surface layer, and peak-to-peak voltage in order to obtain desired electric field strength. The graph which shows the outline of the relationship between humidity and an insulating-layer impedance when an alternating current is applied between an outer side electrode and an inner side electrode, the applied electric current is constant, and humidity changes. The graph which shows the outline of the relationship between the appropriate electric field strength and peak-to-peak voltage in each environment in the state where the layer thickness of a surface layer is a constant value. The flowchart of control which sets an electric field strength to an appropriate value based on the value of the layer thickness of a surface layer, and environmental conditions.

Hereinafter, an embodiment in which the present invention is applied to a printer (hereinafter simply referred to as a printer 100) which is an electrophotographic image forming apparatus will be described.
FIG. 1 is a schematic cross-sectional view of a main part of the printer 100. As shown in FIG. 1, the printer 100 includes four process cartridges 1, an intermediate transfer belt 7 that is stretched by a plurality of stretching rollers and moves in the direction of arrow A in FIG. 1, an exposure device 6 that is an exposure unit, and A fixing device 12 and the like.
FIG. 2 is an enlarged cross-sectional view of one of the four process cartridges 1.

Each process cartridge 1 has a configuration in which a drum-shaped photosensitive member 2, a charging member 3, a developing device 4, and a photosensitive member cleaning member 5 are integrally supported. Each process cartridge 1 can be attached to and detached from the printer 100 main body by releasing a stopper (not shown).
The photoconductor 2 rotates in the clockwise direction in the figure as indicated by the arrow in the figure. The charging member 3 is a roller-shaped charging roller, is in pressure contact with the surface of the photoconductor 2, and is rotated by the rotation of the photoconductor 2. At the time of image formation, a predetermined bias is applied to the charging member 3 by a high voltage power source (not shown) to charge the surface of the photoreceptor 2.
The process cartridge 1 uses a roller-shaped member that contacts the surface of the photoreceptor 2 as the charging member 3 that is a charging unit. However, the charging unit is not limited to this, and non-contact charging such as corona charging is possible. A method may be used.

The exposure device 6 exposes the surface of the photoreceptor 2 based on image information, and forms an electrostatic latent image on the surface of the photoreceptor 2. The exposure device 6 provided in the printer 100 uses a laser beam scanner system using a laser diode, but may have other configurations such as an exposure unit using an LED array.
The photoconductor cleaning member 5 cleans residual toner remaining on the surface of the photoconductor 2 that has passed through a position facing the intermediate transfer belt 7.

The four process cartridges 1 form toner images for the respective colors of yellow, cyan, magenta, and black on the photoreceptor 2. The four process cartridges 1 are arranged in parallel in the surface movement direction of the intermediate transfer belt 7, and transfer the toner images formed on the respective photoreceptors 2 in order to be superimposed on the intermediate transfer belt 7 in order. A visible image is formed on the belt 7.
A primary transfer roller 8 is disposed at a position facing each photoconductor 2 across the intermediate transfer belt 7. A primary transfer bias is applied to the primary transfer roller 8 by a high voltage power source (not shown), and the photoconductor. 2 forms a primary transfer electric field. By forming a primary transfer electric field between the photosensitive member 2 and the primary transfer roller 8, the toner image formed on the surface of the photosensitive member 2 is transferred to the surface of the intermediate transfer belt 7. One of a plurality of stretching rollers that stretch the intermediate transfer belt 7 is rotated by a drive motor (not shown), so that the intermediate transfer belt 7 moves in the direction of the arrow in the figure. A full color image is formed on the surface of the intermediate transfer belt 7 by sequentially transferring the toner images of the respective colors on the surface of the intermediate transfer belt 7 moving on the surface.

With respect to the position where the four process cartridges 1 are opposed to the intermediate transfer belt 7, the intermediate transfer belt 7 is located on the downstream side of the surface movement direction with respect to the secondary transfer counter roller 9a which is one of the stretching rollers. A secondary transfer roller 9 is disposed at a position opposed to the belt 7 and forms a secondary transfer nip with the intermediate transfer belt 7. A transfer sheet which is a transfer material conveyed in the direction of arrow B in FIG. 1 by applying a predetermined voltage between the secondary transfer roller 9 and the secondary transfer counter roller 9a to form a secondary transfer electric field. When P passes through the secondary transfer nip, the full-color image formed on the surface of the intermediate transfer belt 7 is transferred onto the transfer paper P.
A fixing device 12 is disposed downstream of the secondary transfer nip in the conveyance direction of the transfer paper P. The transfer paper P that has passed through the secondary transfer nip reaches the fixing device 12, the full color image transferred onto the transfer paper P is fixed by heating and pressurization in the fixing device 12, and the transfer paper P on which the image is fixed is The data is output outside the printer 100.
On the other hand, the toner remaining on the surface of the intermediate transfer belt 7 without being transferred to the transfer paper P at the secondary transfer nip is collected by the transfer belt cleaning device 11.

Next, the developing device 4 included in the process cartridge 1 will be described with reference to FIGS. 2 and 3.
FIG. 3 is a cross-sectional explanatory view in the vicinity of the rotation shafts of the toner conveying member 106, the toner agitating member 108, and the toner supply roller 105 that are arranged substantially linearly in the vertical direction in the developing device 4.
The developing device 4 includes a toner storage chamber 101 that stores toner as a developer and a toner supply chamber 102 provided below the toner storage chamber 101, and partitions the toner storage chamber 101 and the toner supply chamber 102. Thus, a partition member 110 is provided.
As shown in FIG. 3, the partition member 110 is provided with a plurality of openings. The plurality of openings of the partition member 110 are provided with a supply port 111 for supplying the toner in the toner storage chamber 101 to the toner supply chamber 102 and a return port 107 for returning the toner in the toner supply chamber 102 to the toner storage chamber 101. It has been.

Below the toner supply chamber 102, a toner carrying roller 103, which is a developer carrying member, is provided. In the toner supply chamber 102, a toner supply roller 105 that is a developer supply member that supplies toner to the surface of the toner carrying roller 103 is provided in contact with the surface of the toner carrying roller 103. Further, a toner layer regulating member that regulates the layer thickness of the toner that is supplied to the toner supply chamber 102 on the surface of the toner carrying roller 103 by the toner supply roller 105 and goes to the opposite portion between the photoreceptor 2 and the toner carrying roller 103. 104 is provided in contact with the surface of the toner carrying roller 103.
The toner carrying roller 103 is disposed in a non-contact manner with respect to the photoreceptor 2 and is applied with a predetermined bias from a high voltage power source (not shown).

A toner conveying member 106 is provided in the toner accommodating chamber 101 for conveying the toner in the toner accommodating chamber 101 in a direction parallel to the rotation axis of the photoreceptor 2 (a direction perpendicular to the paper surface in FIG. 2).
The toner stored in the toner storage chamber 101 is a toner prepared by a polymerization method, has an average particle diameter of 6.5 [μm], a circularity of 0.98, an angle of repose of 33 [°], and an external additive. The toner contains strontium titanate as a toner. The toner used in the printer 100 to which the present invention is applied is not limited to this.

As shown in FIG. 3, the toner conveying member 106 provided in the toner storage chamber 101 is a member having a rotating shaft that combines a conveying screw shape 106a and a conveying plate shape 106b. The toner conveying member 106 is configured to convey the toner in the toner storage chamber 101 in a substantially horizontal direction (in the direction of arrow C in FIG. 3) parallel to the rotation axis of the toner conveying member 106 by the rotation operation of the conveying screw shape 106a. ing. The developing device 4 is configured to include a conveying screw shape 106a that conveys toner in a direction parallel to the rotation axis of the toner conveying member 106, but the developer conveying member is not limited to this, and a conveying belt, What has a conveyance function, such as a coil-shaped rotary body, can be used. Furthermore, what has these conveyance functions and what has a loosening function, such as a paddle formed by bending a plate member such as a blade or a wire, may be combined.
Further, in the developing device 4 of the present embodiment, the toner is transported from the toner storage chamber 101 toward the toner supply roller 105 in a direction substantially perpendicular to the rotation axis of the toner transport member 106 and substantially vertically downward. ing. The toner may be transported in a substantially horizontal direction perpendicular to the rotation axis of the toner transport member 106 as the toner transport direction.

A toner stirring member 108 is disposed in the toner supply chamber 102 vertically below the partition member 110.
As shown in FIG. 3, the toner stirring member 108 is a member having a rotating shaft in which a stirring screw shape 108 a and a stirring plate shape 108 b are combined. The toner stirring member 108 can convey the toner in the toner supply chamber 102 in a substantially horizontal direction (in the direction of arrow D or E in FIG. 3) parallel to the rotation axis of the toner stirring member 108 by rotating the stirring screw shape 108 a. It has become.

As shown in FIG. 3, the stirring screw shape 108a of the toner stirring member 108 has a helical shape so as to convey the toner in the direction toward the outside (in the direction of arrow D in FIG. 3) across the supply port 111 in the axial direction. Feathers are provided. Further, in the stirring screw shape 108a of the toner stirring member 108, spiral wings are reversely wound on the outer side and the inner side of the two return ports 107 in the axial direction. Therefore, the toner supplied from the supply port 111 to the toner supply chamber 102 is conveyed outward in the axial direction (in the direction of arrow D) by the rotation of the stirring screw shape 108a of the toner stirring member 108, and reaches the outer side than the return port 107. The toner is conveyed toward the return port 107 by the stirring screw shape 108a whose wing portion is wound in reverse.
The toner conveying direction by the stirring screw shape 108 a is opposite between the outer side and the inner side in the axial direction across the return port 107, and a conveying force is applied to the toner toward the return port 107. Then, the toner is collected from both sides in the axial direction and pushed up in a mountain shape. Accordingly, when the toner supplied from the toner storage chamber 101 to the toner supply chamber 102 through the supply port 111 or the return port 107 is excessive, the toner pushed up in the mountain shape by the return port 107 is transferred to the toner supply chamber. 102 is returned to the toner storage chamber 101 through the return port 107.
The toner stirring member 108 has a role of stirring the toner in the toner supply chamber 102 and further supplying the toner to the toner carrying roller 103 and the toner supply roller 105 in the lower part.

The surface of the toner supply roller 105 is covered with a foam material having a structure having pores (cells), and the toner supplied into the toner supply chamber 102 is efficiently attached and taken in, and the toner carrying roller 103 and The toner is prevented from deteriorating due to pressure concentration at the contact portion.
In addition, this foaming material is set to an electrical resistance value of 10 ³ to 10 ¹⁴ [Ω].
A supply bias is applied to the toner supply roller 105, and assists the operation of pressing the toner preliminarily charged at the contact portion with the toner carrying roller 103 against the toner carrying roller 103. The toner supply roller 105 rotates in the counterclockwise direction in FIG. 2 as indicated by an arrow in FIG. 2 and supplies the toner adhered to the surface so as to be applied to the surface of the toner carrying roller 103.

A toner layer regulating member 104, which is a developer regulating member, is disposed so as to come into contact with the surface of the toner carrying roller 103 on the downstream side in the surface movement direction of the toner carrying roller 103 from the position where the toner supply roller 105 abuts. The toner supplied from the toner supply roller 105 to the surface of the toner carrying roller 103 is conveyed to a position where the toner layer regulating member 104 comes into contact with the rotation of the toner carrying roller 103.
As the toner layer regulating member 104, a metal leaf spring material such as SUS304CSP, SUS301CSP, or phosphor bronze can be used, and the free end thereof is applied to the surface of the toner carrying roller 103 with a pressing force of 10 to 100 [N / m]. By contacting the toner on the toner carrying roller 103 under the pressing force, the toner layer is thinned and charges are applied to the toner by frictional charging.
In addition, a bias is applied to the toner layer regulating member 104 in order to assist the frictional charging of the toner.

The photoreceptor 2 is not in contact with the toner carrying roller 103 and rotates in the clockwise direction in FIG. For this reason, in the developing region where the toner carrying roller 103 and the photosensitive member 2 face each other, the surface moving direction of the toner carrying roller 103 and the surface moving direction of the photosensitive member 2 are the same direction.
The thinned toner layer on the toner carrying roller 103 is conveyed to the development region by the rotation of the toner carrying roller 103 and is formed by the bias applied to the toner carrying roller 103 and the electrostatic latent image on the photoreceptor 2. The electrostatic latent image on the surface of the photoreceptor 2 is developed by moving to the surface of the photoreceptor 2 in accordance with the latent image electric field.

  A neutralization seal 109, which is a developer neutralizing member, abuts the toner carrying roller 103 at a location where the toner that is not used for development in the development region and remains on the toner carrying roller 103 returns to the toner supply chamber 102 again. And is sealed so that the toner does not leak out of the developing device 4. A bias is applied to the static elimination seal 109 to assist the static elimination capability.

Next, a method for developing the toner on the toner carrying roller 103 on the photoreceptor 2 in this embodiment will be described in detail.
The toner supplied on the surface of the toner carrying roller 103 at the toner supply position is developed from the toner supply position as the toner carrying roller 103 rotates while hopping on the surface of the toner carrying roller 103 for the reason described later. It is transported towards the area. The toner transported to the developing area adheres to the electrostatic latent image portion on the surface of the photosensitive member 2 by a developing electric field between the toner carrying roller 103 and the electrostatic latent image on the photosensitive member 2, thereby developing the toner. Is done. The toner that has not contributed to the development is further conveyed by the rotation of the toner carrying roller 103 while hopping, and is repeatedly used.

Next, a specific configuration of the toner carrying roller 103 in the present embodiment will be described.
FIG. 4 is a schematic diagram when the toner carrying roller 103 is viewed from a direction orthogonal to the rotation axis in order to explain the electrode arrangement of the toner carrying roller 103 in the present embodiment. For convenience of explanation, the surface layer 36 and the insulating layer 35 are not shown.
FIG. 5 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller 103 according to the present embodiment is cut along a plane orthogonal to the rotation axis thereof.
The toner carrying roller 103 according to the present embodiment is configured by a hollow roller member, and an inner electrode 33a serving as an innermost electrode member or an inner electrode member located on the innermost periphery thereof, and an outermost electrode side thereof. A comb-like outer electrode 34a is provided as an outermost peripheral electrode member that is positioned and to which a voltage (outer voltage) different from a voltage (inner voltage) applied to the inner electrode 33a is applied. An insulating layer 35 is provided between the inner electrode 33a and the outer electrode 34a to insulate them. A surface layer 36 is also provided as a protective layer covering the outer peripheral surface side of the outer electrode 34a. That is, the toner carrying roller 103 according to the present embodiment has a four-layer structure of the inner electrode 33a, the insulating layer 35, the outer electrode 34a, and the surface layer 36 in order from the inner peripheral side.

  The inner electrode 33a also functions as a base of the toner carrying roller 103, and is a metal roller obtained by molding a conductive material such as SUS or aluminum into a cylindrical shape. In addition, as a configuration of the inner electrode 33a, a structure in which a conductive layer made of a metal layer such as aluminum or copper is formed on the surface of a resin roller made of polyacetal (POM), polycarbonate (PC), or the like. As a method of forming this conductive layer, a method of forming by metal plating, vapor deposition, or the like, a method of adhering a metal film to the roller surface, or the like can be considered.

  The outer peripheral surface side of the inner electrode 33 a is covered with an insulating layer 35. In this embodiment, the insulating layer 35 is formed of polycarbonate, alkyd melamine, or the like. In the present embodiment, the thickness of the insulating layer 35 is preferably in the range of 3 [μm] to 50 [μm]. If it is smaller than 3 [μm], the insulation between the inner electrode 33a and the outer electrode 34a cannot be sufficiently maintained, and there is a high possibility that leakage occurs between the inner electrode 33a and the outer electrode 34a. Become. On the other hand, if it is larger than 50 [μm], the electric field created between the inner electrode 33a and the outer electrode 34a is less likely to be formed outside the surface layer 36, and a strong flare electric field (external electric field) is formed outside the surface layer 36. It becomes difficult to form. In this embodiment, the layer thickness of the insulating layer 35 made of melamine resin is 20 [μm]. The insulating layer 35 can be formed with a uniform film thickness on the inner electrode 33a by a spray method, a dip method or the like.

  An outer electrode 34 a is formed on the insulating layer 35. In the present embodiment, the outer electrode 34a is formed of a metal such as aluminum, copper, or silver. Various methods are conceivable as a method for forming the comb-shaped outer electrode 34a. For example, there is a method in which a metal film is formed on the insulating layer 35 by plating or vapor deposition, and a comb-like electrode is formed by photoresist etching. A method of forming a comb-like electrode by attaching a conductive paste on the insulating layer 35 by an ink jet method or screen printing is also conceivable.

  The outer peripheral surfaces of the outer electrode 34 a and the insulating layer 35 are covered with a surface layer 36. The toner is charged by contact friction with the surface layer 36 when hopping is repeated on the surface layer 36. In this embodiment, silicone, nylon (registered trademark), urethane, alkyd melamine, polycarbonate, or the like is used as a material for the surface layer 36 in order to give the toner a normal charging polarity (negative polarity in this embodiment). In this embodiment, polycarbonate is employed. In addition, since the surface layer 36 also has a role of protecting the outer electrode 34a, the layer thickness of the surface layer 36 is preferably in the range of 3 [μm] to 40 [μm]. If it is smaller than 3 [μm], the outer electrode 34a may be exposed due to film scraping due to use over time. On the other hand, if it is larger than 40 [μm], the electric field generated between the inner electrode 33a and the outer electrode 34a is hardly formed outside the surface layer 36, and a strong flare electric field is formed outside the surface layer 36. It becomes difficult. In the present embodiment, the surface layer has a thickness of 20 [μm]. The surface layer 36 can be formed by a spray method, a dipping method, or the like, similarly to the insulating layer 35.

  In the present embodiment, the electric field created between the inner electrode 33a and the outer electrode 34a, more specifically, the portion of the inner electrode 33a that does not face the outer electrode 34a (the inner side located between the comb teeth of the outer electrode 34a). The electric field generated between the electrode 33a portion and the comb-teeth portion of the outer electrode 34a is formed outside the surface layer 36, so that the toner on the toner carrying roller 103 is hopped, whereby the toner is clouded. Let At this time, the toner on the toner carrying roller 103 reciprocates while flying between a surface layer portion facing the inner electrode 33a via the insulating layer 35 and a surface layer portion facing the outer electrode 34a adjacent thereto. You will be hopping.

  In order to stably form a toner in the cloud, it is important to form a flare electric field having a corresponding magnitude. To form such a large flare electric field, the inner electrode 33a and the outer electrode 34a are formed. It is necessary to form a large potential difference between However, in order to stably form such a large potential difference, it is important to stably and effectively insulate between the inner electrode 33a and the outer electrode 34a to prevent leakage. When the two types of electrodes for forming the electric field for flare are each formed in a comb-like shape and arranged concentrically as in the conventional case, and each comb-tooth portion enters between the other comb-tooth. When the formation quality of the comb-like electrode is poor, the insulation between the two types of electrodes is remarkably lowered, and leakage is likely to occur. Specifically, for example, when an electrode is formed by etching, a part of the metal film to be removed remains, or when an electrode is formed by an ink jet method or a screen printing method, a conductive paste adheres between the electrodes. Can happen. When such a situation occurs, leakage easily occurs between the two types of electrodes, and an appropriate flare electric field cannot be formed. In the conventional configuration, even if the comb-like electrodes are formed with high quality on the resin surface of the roller, the outer peripheral surface side is covered with an insulating material after forming the two types of comb-like electrodes. In order to obtain insulation between the electrodes by filling the insulating material, the interface between the resin surface of the roller and the insulating material is formed between the electrodes, and leakage through this interface is likely to occur, and a relatively large voltage is applied. The insulation between the electrodes is significantly reduced.

  The toner carrying roller 103 of the present embodiment has a configuration in which the insulating layer 35 is provided on the inner electrode 33a and the comb-shaped outer electrode 34a is formed on the insulating layer. There is no such interface. Further, in the manufacturing stage of the toner carrying roller 103, the possibility that a conductive material that may cause a leak is interposed between the electrodes can be extremely reduced. Therefore, according to the present embodiment, the inner electrode 33a and the outer electrode 34a can be insulated stably and effectively, and leakage can be effectively prevented even when a relatively large voltage is applied.

  In the present embodiment, the electrode width of the outer electrode 34a (the width of each comb tooth portion) is preferably 10 [μm] or more and 120 [μm] or less. If it is smaller than 10 [μm], the electrode may be too thin and the electrode may be disconnected in the middle. On the other hand, if it is larger than 120 [μm], the voltage at a location where the distance from the power-supplied portion 34b of the outer electrode 34a is low, and it becomes difficult to hop toner stably and effectively at that location. As shown in FIG. 4, the power-supplied portions 34 b of this embodiment are provided at both ends in the axial direction on the outer peripheral surface of the toner carrying roller 103. Therefore, in this embodiment, when the electrode width of the outer electrode 34a is larger than 120 [μm], the flare electric field at the central portion in the axial direction of the toner carrying roller 103 is relatively lower than the flare electric fields at both ends in the axial direction. Thus, it becomes difficult to hop the toner carried in the central portion in the axial direction stably and effectively.

In the present embodiment, it is preferable that the electrode pitch (distance between the comb teeth portions) of the outer electrode 34a is equal to or wider than the electrode width. If it is smaller than the electrode width, most of the lines of electric force from the inner electrode 33a converge on the outer electrode 34a before coming out of the outer surface 36, and the flare electric field formed outside the outer layer 36 becomes weaker. Because it ends up. On the other hand, if the electrode pitch is large, the flare electric field at the center between the electrodes becomes weak. In the present embodiment, the electrode pitch is preferably within the range of not less than the electrode width and not more than 5 times the electrode width.
In this embodiment, both the electrode width and the electrode pitch are set to 80 [μm].

  In this embodiment, the electrode pitch of the outer electrode 34 a is set to be constant over the circumferential direction of the toner carrying roller 103. By making the electrode pitch constant, the flare electric field created between the inner electrode 33 a and the outer electrode 34 a becomes substantially uniform over the circumferential direction on the toner carrying roller 103. Therefore, it is possible to achieve uniform toner hopping in the circumferential direction at the development position, and uniform development is possible.

Next, the voltage applied to the inner electrode 33a and the outer electrode 34a will be described.
An inner voltage that is a first voltage and an outer voltage that is a second voltage are applied to the inner electrode 33a and the outer electrode 34a on the toner carrying roller 103 from the first pulse power source 25A and the second pulse power source 25B, respectively. A rectangular wave is most suitable for the inner voltage and the outer voltage applied by the first pulse power supply 25A and the second pulse power supply 25B. However, not limited to this, for example, a sine wave or a triangular wave may be used. In this embodiment, the electrode for forming the flare electrode has a two-phase configuration of the inner electrode 33a and the outer electrode 34a, and each electrode (33a, 34a) has a voltage having a phase difference π from each other. Applied.

FIG. 6 is a graph showing an example of the inner voltage and the outer voltage applied to the inner electrode 33a and the outer electrode 34a, respectively.
In this embodiment, each voltage is a rectangular wave, and the inner voltage and the outer voltage applied to the inner electrode 33a and the outer electrode 34a, respectively, have the same magnitude (peak-to-peak voltage Vpp) with the phase shifted by π. Voltage. Therefore, there is always a potential difference of Vpp between the inner electrode 33a and the outer electrode 34a. Due to this potential difference, an electric field is generated between the electrodes, and the toner hops on the surface layer 36 by the flare electric field formed outside the surface layer 36 of the electric field. In the present embodiment, Vpp is preferably in the range of 100 [V] to 2000 [V]. When Vpp is smaller than 100 [V], a sufficient flare electric field cannot be formed on the surface layer 36, and it becomes difficult to stably hop the toner. On the other hand, if Vpp is larger than 2000 [V], there is a high possibility that leakage occurs between the electrodes due to use over time. In this embodiment, Vpp is set to 500 [V].
In the present embodiment, the center value V0 of the inner voltage and the outer voltage is set between the image portion potential (the potential of the electrostatic latent image portion) and the non-image portion potential (the potential of the background portion), and the development condition Depending on the situation. The same effect can be obtained even if the value of the center value V0 is fixed and the duty is changed.

  In the present embodiment, the frequency f of the inner voltage and the outer voltage is preferably 0.1 [kHz] or more and 10 [kHz] or less. If it is less than 0.1 [kHz], toner hopping may not be able to keep up with the development speed. On the other hand, if it is larger than 10 [kHz], the movement of the toner cannot follow the switching of the electric field, and it becomes difficult to stably hop the toner. In the present embodiment, the frequency f is set to 500 [Hz].

  As shown in FIG. 4, the developing device 4 is configured such that the first pulse power supply 25 </ b> A applies a voltage to the carrying roller rotation shaft 33 b of the toner carrying roller 103. The carrying roller rotating shaft 33b functions as a power feeding unit for the inner electrode 33a. The second pulse power supply 25B is connected to a conductive roller (not shown), and this conductive roller contacts the power-supplied portions 34b provided at both ends in the axial direction on the outer peripheral surface of the toner carrying roller 103. A voltage is applied to the outer electrode 34a.

  If the electric field formed between the inner electrode 33a and the outer electrode 34a is too strong, a leak occurs between the outer electrode 34a and the inner electrode 33a, and the electrode may be destroyed or the toner layer Leakage may occur between the regulating member 104 and the outer electrode 34a, and the surface layer 36 of the toner carrying roller 103 may be damaged. For this reason, in the developing device 4, the potential difference (peak-to-peak voltage Vpp) between the inner electrode 33a and the outer electrode 34a is such that the electric field formed between the inner electrode 33a and the outer electrode 34a has an appropriate strength. Is set.

Next, the characteristic part of the developing device 4 of the present embodiment will be described.
Even if the setting of the voltage applied to the inner electrode 33a and the outer electrode 34a is the same, the strength of the electric field formed between the inner electrode 33a and the outer electrode 34a differs when the layer thickness of the surface layer 36 is different. . Further, the layer thickness of the surface layer 36 is not constant because the thickness of the surface layer 36 varies due to manufacturing or decreases due to wear due to long-term use. Therefore, if the setting of the voltage applied to the inner electrode 33a and the outer electrode 34a is always constant and the value of the peak-to-peak voltage Vpp is constant, the electric field strength varies depending on the layer thickness of the surface layer 36, and the image Problems such as a decrease in density or leakage between the inner electrode 33a and the outer electrode 34a or between the outer electrode 34a and the toner layer regulating member 104 occur.
In order to prevent such a problem, the developing device 4 always detects the state of the surface layer 36 that is the outermost layer of the toner carrying roller 103 and feeds back to the bias control applied to the inner electrode 33a and the outer electrode 34a. . As a result, the flare state can always be made constant, and the occurrence of defects such as image defects can be prevented.

As shown in FIG. 2, the developing device 4 includes a surface layer impedance measuring device 130 and an insulating layer impedance measuring device 140. The surface layer impedance measuring device 130 measures the impedance of the surface layer 36 by applying an alternating current between the toner layer regulating member 104 in contact with the surface of the toner carrying roller 103 and the outer electrode 34a. The insulating layer impedance measuring device 140 measures the impedance of the insulating layer 35 by applying an alternating current between the outer electrode 34a and the inner electrode 33a.
Then, according to the measurement results of the surface layer impedance measuring device 130 and the insulating layer impedance measuring device 140, the first pulse power supply 25A is set so that the electric field formed between the outer electrode 34a and the inner electrode 33a has an appropriate strength. And the setting of the voltage which the 2nd pulse power supply 25B applies is adjusted.

Hereinafter, the case where the layer thickness of the surface layer 36 decreases due to wear by continuing to use the developing device 4 will be described.
Since the toner carrying roller 103 moves on the surface with the toner layer regulating member 104, the toner supply roller 105, the static elimination seal 109, etc. in contact with the surface, the surface layer 36 is scraped over time. For this reason, by continuing to use the developing device 4, the layer thickness of the surface layer 36 becomes thinner than in the initial state.

FIG. 7 shows the relationship between the layer thickness of the surface layer 36 and the electric field strength when the layer thickness of the surface layer 36 of the toner supply roller 105 decreases in a state where the electric field is not controlled (the value of the peak-to-peak voltage Vpp is constant). It is a graph which shows an outline.
As shown in FIG. 7, when the electric field is not controlled, in the initial state of the developing device 4, when the layer thickness of the surface layer 36 is x1 [μm], the electric field strength is E1 [V / m]. When the layer thickness of the surface layer 36 becomes x3 [μm], the electric field strength increases to E3 [V / m]. When the electric field strength whose proper value is E1 [V / m] is increased to E3 [V / m], a leak occurs between the toner layer regulating member 104 and the outer electrode 34a, and the surface layer 36 may be damaged. .

Next, in the developing device 4, in order to confirm the relationship between the thickness of the surface layer 36 and the impedance, an alternating current is applied between the toner layer regulating member 104 in contact with the surface of the toner carrying roller 103 and the outer electrode 34 a. Each impedance value was measured under the condition that the thickness of the surface layer 36 was different.
A graph showing an outline of the relationship between the layer thickness of the surface layer 36 and the impedance (hereinafter referred to as surface layer impedance H) at this time is shown in FIG. As shown in FIG. 8, when the surface layer 36 is thin and the layer thickness tx is small, the surface layer impedance H is low, and when the surface layer 36 is thick and the layer thickness tx is large, the surface layer impedance H is high, depending on the size of the layer thickness tx. It can be seen that the surface impedance H is different.

FIG. 9 is a graph showing an outline of the relationship between the layer thickness tx of the surface layer 36 of the toner carrying roller 103 and the peak-to-peak voltage Vpp in order to obtain a desired electric field strength E.
In the configuration shown in the graph of FIG. 9, the peak-to-peak voltage Vpp is adjusted to be y1 [V] when the layer thickness tx of the surface layer 36 is x1 [μm], and the peak when the layer thickness tx is x2 [μm]. By adjusting the to-peak voltage Vpp to be y2 [V], the electric field strength E can be made constant at a desired value.
For this reason, for example, when the initial layer thickness tx of the surface layer 36 is x1 [μm] and the peak-to-peak voltage Vpp at which a desired electric field intensity E is obtained is y1 [V], the layer of the surface layer 36 due to wear over time. Even when the thickness tx is reduced to x3 [μm], the electric field intensity E is kept constant at a desired value by adjusting the applied voltage so that the peak-to-peak voltage Vpp becomes y3 [V]. I can do it.

The relationship between the peak-to-peak voltage Vpp, the electric field strength E, and the layer thickness tx of the surface layer 36 at this time can be expressed as the following formula (1).
Vpp = f _E (tx) (1)
Therefore, not only when the layer thickness tx of the surface layer 36 decreases due to wear over time, but also when the layer thickness tx of the surface layer 36 varies due to manufacturing variations or the like, the layer thickness tx of the surface layer 36 is measured in advance. Then, according to the measured value, the peak-to-peak voltage Vpp at which the electric field intensity E of the electric field forming the flare takes a desired value can be calculated from the relational expression shown in Expression 1. Therefore, even if the initial layer thickness tx of the surface layer 36 is x1 [μm] and the layer thickness tx of the surface layer 36 is x2 [μm] larger than the initial setting due to manufacturing variations, the peak-to-peak The electric field strength E can be kept constant at a desired value by adjusting the applied voltage so that the voltage Vpp becomes y2 [V].
By performing the control as described above, the problem occurs when the electric field strength becomes too small due to the decrease or variation in the layer thickness tx of the surface layer 36, or the electric field becomes too strong. Can be prevented. An inconvenience caused by the electric field strength being too small is a decrease in image density. In addition, problems that occur when the electric field becomes too strong include electrode destruction due to leakage between the outer electrode 34a and the inner electrode 33a, and the relationship between the outer electrode 34a, the toner layer regulating member 104, and the outer electrode 34a. In the developing device 4, when the surface layer 36 in the initial state where the layer thickness tx was x1 [μm] becomes x3 [μm] due to wear over time, the above equation (1) is satisfied. Based on this, by adjusting the peak-to-peak voltage Vpp to y3 [μm], the electric field strength E of the electric field forming the flare is set to a desired constant value, and the surface layer is leaked by the toner layer regulating member 104 and the outer electrode 34a. 36 can be prevented from being destroyed. Even if the layer thickness tx of the surface layer 36 is larger than x1 due to manufacturing variations, the flare can be obtained by adjusting the peak-to-peak voltage Vpp to y2 [μm] based on the above formula (1). The electric field strength E of the electric field forming the toner can be set to a desired constant value, and density fluctuation due to insufficient toner flight can be prevented.

When the conditions of the installation environment of the developing device 4 change, the characteristic value (water content etc.) of the insulating material changes and the material temperature changes, and the impedance characteristic changes.
FIG. 10 is a graph showing an outline of the relationship between humidity and impedance when an alternating current is applied between the outer electrode 34a and the inner electrode 33a, the applied current is constant, and the humidity changes. An insulating layer 35 is interposed between the outer electrode 34a and the inner electrode 33a. As shown in FIG. 10, the impedance of the insulating material changes when the humidity changes, and when the humidity is low, the impedance is higher than when the humidity is high. Is high.
Since the outer peripheral surface side of the insulating layer 35 is covered with the outer electrode 34a and the surface layer 36, wear with time due to contact with other members does not occur, and the layer thickness is constant. Therefore, since there is no change in impedance due to a decrease in the layer thickness over time, only the change in impedance due to environmental change can be detected by measuring the impedance of the insulating layer 35 (insulating layer impedance J).

  The above-described change in the surface layer impedance H includes not only a change in impedance due to a decrease in layer thickness due to wear over time, but also a change in impedance due to environmental changes. Therefore, by correcting the change in the surface layer impedance H with the change in the insulating layer impedance J, it is possible to accurately calculate the layer thickness tx of the surface layer 36.

  Further, when the environment such as temperature and humidity changes, the charge amount of the toner also changes. For example, the charge amount is high in a low temperature and low humidity environment, and the charge amount is low in a high temperature and high humidity environment. Such a change in the toner charge amount changes the electrostatic adhesion force between the toner and the toner carrying roller 103. For this reason, when the electric field for flying the toner is set to an appropriate electric field strength E in a low temperature and low humidity environment, the toner will fly too much in the high temperature and high humidity environment, and the toner will not return to the toner carrying roller 103. There is a problem that scattering occurs and the inside of the apparatus is soiled.

  For this reason, the developing device 4 calculates the optimum electric field strength E in consideration of the influence of the environmental change from the measurement result of the insulating layer impedance J, and based on the optimum electric field strength E, the surface layer impedance H, and the insulating layer impedance J. Based on the calculated layer thickness tx of the surface layer 36, the voltage applied to the outer electrode 34a and the inner electrode 33a is determined.

FIG. 11 is a graph showing an outline of the relationship between the appropriate electric field intensity E and the peak-to-peak voltage Vpp in each environment with the layer thickness tx of the surface layer 36 being a certain value.
In FIG. 11, the high temperature and high humidity environment indicates an appropriate electric field intensity E by a dashed line, the normal environment by a solid line, and the low temperature and low humidity environment by a broken line.
For example, the peak-to-peak voltage Vpp when the layer thickness tx at the time of control is determined to be x1 [μm] is yh [V] in a high temperature and high humidity environment, ym [V] in a normal environment, and low temperature and low humidity. Under the environment, each is adjusted to be yl [V].
Therefore, the right side “f _E (tx)” of the equation (1) represented by “Vpp = f _E (tx)” is an equation determined by the environmental conditions.

FIG. 12 shows a flowchart of control for setting the electric field strength E to an appropriate value based on the value of the layer thickness tx of the surface layer 36 and the environmental conditions.
In the flowchart shown in FIG. 12, the surface layer impedance H and the insulation layer impedance J are measured (S1 and S2), and the environmental coefficient is determined based on the measurement result of the insulation layer impedance J (S3). Based on the determined environmental coefficient, an appropriate electric field strength E under the current environmental conditions is determined (S4). Further, the layer thickness tx of the surface layer 36 is calculated based on the measurement result of the insulating layer impedance J and the measurement result of the surface layer impedance H (S5). Based on the layer thickness tx and the electric field strength E, a peak-to-peak voltage Vpp at which an appropriate electric field strength E is obtained is determined (S6).
The voltage applied to the inner electrode 33a and the outer electrode 34a is set so as to be the value of the peak-to-peak voltage Vpp determined by the control of S1 to S6, and printing is performed (S7).
By performing such control, even if the environmental conditions change or the layer thickness tx of the surface layer 36 decreases due to long-term use, the image density decreases due to insufficient toner flight, the toner layer regulating member 104 and the outer electrode Generation | occurrence | production of malfunctions, such as damage of the surface layer 36 by the leak between 34a, can be prevented.

  As described above, the developing device 4 of the present embodiment includes the inner electrode 33a and the outer electrode 34a that are a plurality of types of electrode members to which different voltages are applied, and the toner that is the developer carried on the outer peripheral surface is supplied to the developing region. An electric field is formed between the inner electrode 33a and the outer electrode 34a by applying different voltages to the toner carrying roller 103, which is a developer carrying member for conveyance, and the inner electrode 33a and the outer electrode 34a. And a first pulse power source 25A and a second pulse power source 25B constituting electric field forming means for causing the toner to fly on the outer peripheral surface of the toner carrying roller 103 by this electric field, and on the outer peripheral surface of the toner carrying roller 103 in the developing region. The developing device develops an electrostatic latent image on the photosensitive member 2 using flying toner. A surface layer impedance measuring device 130 is provided as a surface layer characteristic measuring unit that is provided on the outer peripheral surface side of the inner electrode 33a and the outer electrode 34a, which are two types of electrode members, and measures the characteristics of the surface layer 36. By providing a surface layer impedance measuring device 130 as a means for measuring the characteristics of the surface layer 36 that is a layer on the outer peripheral surface side of the electrode member of the toner carrying roller 103, an optimum value of the electric field for causing the toner as the developer to fly is calculated. be able to.

  Further, the surface layer impedance measuring device 130 which is a surface layer characteristic measuring unit of the developing device 4 measures the layer thickness of the surface layer 36 based on the measured impedance as the surface layer 36 characteristic. Thereby, it is possible to measure the layer thickness which is a characteristic of the surface layer 36 which is reduced by wear over time.

  Further, the surface layer impedance measuring device 130 that is a surface layer characteristic measuring unit included in the developing device 4 is a surface layer impedance detecting unit that detects the impedance of the surface layer 36. By measuring the impedance of the surface layer 36, the layer thickness of the surface layer 36 can be measured.

  Further, the developing device 4 includes a toner layer regulating member 104 that is a regulating member that regulates the amount of toner on the outer circumferential surface of the toner carrying roller 103 that contacts the outer circumferential surface of the toner carrying roller 103 and passes through the contact position. The surface impedance measuring apparatus 130 measures the impedance between the outer electrode 34a of the two types of electrode members and the toner layer regulating member 104. As a result, the impedance of the surface layer 36 between the outer electrode 34 a and the toner layer regulating member 104 can be measured.

  Further, the developing device 4 uses an electric field forming unit so that the electric field formed between the inner electrode 33a and the outer electrode 34a, which are different types of electrode members, is constant based on the detection result of the surface impedance measuring device 130. To control. Thereby, even if the layer thickness of the surface layer 36 decreases with time, an appropriate electric field can be formed on the surface of the surface layer 36, and a decrease in image density and leakage between electrode members can be prevented.

  In addition, the developing device 4 is a voltage applied to the inner electrode 33a and the outer electrode 34a by the first pulse power source 25A and the second pulse power source 25B constituting the electric field forming unit based on the detection result of the surface impedance measuring device 130. To control. Thereby, based on the detection result of the surface impedance measuring apparatus 130, control can be performed so that the electric field becomes constant.

  Further, the developing device 4 includes an insulating layer impedance measuring device 140 as an inter-electrode member impedance measuring unit that measures impedance between the inner electrode 33a and the outer electrode 34a which are different types of electrode members, and measures the insulating layer impedance. Based on the measurement result of the device 140, an environmental coefficient that is an electric field control coefficient is determined, and the control of the electric field forming unit based on the detection result of the surface impedance measurement device 130 is corrected. As a result, even if the installation environment of the developing device 4 changes, an appropriate electric field can be formed between the inner electrode 33a and the outer electrode 34a in accordance with the environment. Leakage can be prevented.

  Further, as shown in FIG. 5, the developing device 4 arranges the inner electrode 33a and the outer electrode 34a, which are two kinds of electrode members, at positions different from each other in the normal direction of the outer peripheral surface, and the inner electrode 33a and the outer electrode 34a. An insulating layer 35 is interposed therebetween. Thereby, the inner electrode 33a and the outer electrode 34a can be stably and effectively insulated, and leakage can be effectively prevented even when a relatively large voltage is applied.

  Further, the insulating layer impedance measuring device 140 as the inter-electrode member impedance measuring means detects the impedance of the insulating layer 35 by measuring the impedance between the inner electrode 33a and the outer electrode 34a. Since the outer peripheral surface side of the insulating layer 35 is covered with the outer electrode 34a and the surface layer 36, there is no change in impedance due to a decrease in the layer thickness over time, so the impedance of the insulating layer 35 (insulating layer impedance J ) Can be used to detect only changes in impedance due to environmental changes.

  Further, the printer 100 according to the present embodiment develops the electrostatic latent image by supplying toner as a developer to the latent image formed on the photoreceptor 2 as a latent image carrier by a developing unit. The image forming apparatus forms an image on the transfer paper P by finally transferring the obtained image onto the transfer paper P as a recording material. The printer 100 can prevent the image density from being lowered and the leakage between the electrode members by using the developing device 4 described above as the developing unit, so that good image formation can be performed.

DESCRIPTION OF SYMBOLS 1 Process cartridge 2 Photoconductor 3 Charging member 4 Developing device 5 Photoconductor cleaning member 6 Exposure device 7 Intermediate transfer belt 8 Primary transfer roller 9 Secondary transfer roller 9a Secondary transfer counter roller 11 Transfer belt cleaning device 12 Fixing device 25A First Pulse power source 25B Second pulse power source 33a Inner electrode 33b Carrying roller rotating shaft 34a Outer electrode 34b Powered part 35 Insulating layer 36 Surface layer 100 Printer 101 Toner storage chamber 102 Toner supply chamber 103 Toner support roller 104 Toner layer regulating member 105 Toner supply roller 106 Toner conveying member 106a Conveying screw shape 106b Conveying plate shape 107 Return port 108 Toner stirring member 108a Stirring screw shape 108b Stirring plate shape 109 Static elimination seal 110 Partition member 111 Supply port 130 Surface impedance measurement Device 140 Insulating layer impedance measuring device H Surface layer impedance J Insulating layer impedance P Transfer paper tx Layer thickness Vpp Peak-to-peak voltage

JP-A-3-21967 JP 2002-341656 A JP 2004-286837 A JP 2003-15419 A JP-A-9-269661 JP 2003-84560 A

Claims (9)

A plurality of types of electrode members to which different voltages are applied; a developer carrier for transporting a developer carried on the outer peripheral surface to the development region;
By applying different voltages to the plurality of types of electrode members, an electric field is formed between the different types of electrode members, and the electric field causes the developer to fly on the outer peripheral surface of the developer carrier by this electric field. Forming means,
In a developing device for developing a latent image on the latent image carrier using a developer that flies on the outer peripheral surface of the developer carrier at an opposing portion of the developer carrier and the latent image carrier.
Provided with a surface layer characteristic measuring means for measuring the surface layer characteristics provided on the outer peripheral surface side of the plurality of types of electrode members of the developer carrier ,
The surface layer characteristic measuring means includes surface layer impedance detecting means for detecting the impedance of the surface layer,
A regulating member that regulates the amount of the developer on the outer circumferential surface of the developer carrying body that contacts the outer circumferential surface of the developer carrying body and passes through the contact position;
Surface layer impedance detecting means, a developing device according to claim that you measure the impedance between said plurality several electrode member and the regulating member. The developing device according to claim 1.
The developing device according to claim 1, wherein the surface layer characteristic measuring means measures a layer thickness of the surface layer as the surface layer characteristic . The developing device 請 Motomeko 1 or 2,
2. A developing apparatus according to claim 1, wherein said electric field forming means is controlled based on a detection result of said surface layer impedance detecting means so that said electric field formed between different types of electrode members is constant. The developing device according to claim 3 .
The developing device according to claim 1, wherein the electric field forming means controls voltages applied to the plurality of types of electrode members based on a detection result of the surface impedance detection means. The developing device according to claim 3 or 4 ,
Comprising an electrode member impedance measuring means for measuring impedance between different types of electrode members;
2. A developing apparatus according to claim 1, wherein the control of the electric field forming unit is corrected based on a measurement result of the inter-electrode member impedance measuring unit. The developing device according to any one of claims 1 to 5 ,
A developing apparatus comprising the plurality of types of electrode members arranged at different positions in the normal direction of the outer peripheral surface, and an insulating layer interposed between the different types of electrode members. The developing device according to claim 6 .
A developing device comprising: an insulating layer impedance detecting means for detecting the impedance of the insulating layer by measuring impedance between different types of electrode members. An image obtained by developing the latent image by supplying a developer to the latent image formed on the latent image carrier is finally transferred onto the recording material. In an image forming apparatus that forms an image on top,
As the developing device, an image forming apparatus characterized by using the developing apparatus according to any one of claims 1 to 7. The latent image carrier and the developing device that develops the latent image formed on the latent image carrier with a developer are held as a single unit on a common holder and integrated with the image forming apparatus main body. In the process cartridge configured to be detachable,
As the developing apparatus, process cartridge characterized by using a developing apparatus according to any one of claims 1 to 7.

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