JP2013083718A - Development apparatus and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize toner amount per unit area to be supplied to a development area by a method with a little stress given to toner.SOLUTION: In a development apparatus, an electric field for causing the toner to hop is formed on an outer peripheral surface of a toner carrier roller 2 by applying voltage different from each other to an inside electrode 3a and an outside electrode 4a provided in a toner carrier, respectively. In the development apparatus, unevenness is distributed in a toner carrier area on the outer peripheral surface of the toner carrier roller 2, a regulation blade 23 is provided to abut on a protrusion 6b on the outer peripheral surface of the toner carrier roller 2 on a toner carrier roller rotating direction upstream side in the development area, and the toner in a recess 6a is passed while preventing passing of the toner on the protrusion 6b, of the toner carried on the outer peripheral surface of the toner carrier roller 2.

Description

  The present invention relates to a developing device that develops a latent image by transporting toner on a toner carrying member to a developing region and depositing the toner on the latent image carrying member, and a copying machine and printer provided with the developing device The present invention relates to an image forming apparatus such as a facsimile.

  Conventionally, this type of developing device does not use toner adsorbed on the surface of a toner carrier or a magnetic carrier for development, but uses a flare development system that uses toner hopped on the outer peripheral surface of the toner carrier for development. What was adopted is known. For example, the developing device described in Patent Document 1 includes a cylindrical toner carrier including a plurality of electrodes arranged at a predetermined pitch in the circumferential direction. These electrodes are formed by repeatedly arranging electrode pairs composed of two adjacent electrodes. An alternating electric field is formed between the two electrodes in each electrode pair. As a result, the toner located on one electrode in the electrode pair floats and landes on the other electrode, or floats on the other electrode and landes on the one electrode. The hopping behavior is shown.

  While repeating such hopping, the toner on the toner carrier is transported to the development region by the surface movement accompanying the rotational driving of the toner carrier. In the developing region, the toner that has floated to the vicinity of the latent image on the latent image carrier is attracted to the electric field by the latent image and does not descend toward the electrode of the toner carrier, and adheres to the latent image. In such a configuration, toner that does not exert an attractive force by hopping is used for development instead of toner that is adsorbed on the surface of the toner carrier or a magnetic carrier. As a result, it is possible to realize low potential development that could not be realized by the conventional one-component development method or two-component development method. For example, toner can be selectively attached to an electrostatic latent image having a potential difference of only a few tens [V] with respect to surrounding non-image portions.

  In the developing device of Patent Document 1, a toner carrier having a smooth outer peripheral surface is used, and a layer thickness defining member is brought into contact with the outer peripheral surface of the toner carrier. The toner on the toner carrying member passes between the outer peripheral surface of the toner carrying member and the layer thickness defining member, so that the toner amount per unit area supplied to the developing region becomes a target amount and the toner layer The thickness of the toner layer on the toner carrier is regulated so that the thickness of the toner becomes uniform without unevenness.

  However, in the configuration in which the toner layer thickness on the toner carrier is regulated by passing the toner between the smooth outer peripheral surface of the toner carrier and the layer thickness defining member (regulation region), before entering the regulation region. If there is uneven thickness in the toner layer (thickness unevenness in the direction of the toner carrier rotation axis), the pressure applied to the toner varies in the direction of the toner carrier rotation axis in the regulation region. As a result, the toner layer thickness on the toner carrier after passing through the regulation region may be uneven in the direction of the rotation axis of the toner carrier, which may cause uneven image density. In addition, when the thickness of the toner layer entering the restriction region varies with time, the pressure applied to the toner within the restriction region changes with time, so the amount of toner on the toner carrier after passing through the restriction region is the target. In some cases, the image density is deviated, causing a decrease in image density or an increase in image density.

  Thus, the toner per unit area supplied to the development area when the toner layer thickness after passing the restriction area is uneven in the direction of the rotation axis of the toner carrier or the toner amount after passing the restriction area deviates from the target amount. As a method of suppressing the situation where the amount becomes unstable, there is a method of increasing the contact pressure of the layer thickness regulating member with respect to the outer peripheral surface of the toner carrier. However, in this method, the stress on the toner passing through the restriction region is increased, the deterioration of the toner is promoted, and the life of the toner is shortened.

  The present invention has been made in view of the above background, and an object of the present invention is to develop a toner that can stabilize the amount of toner per unit area supplied to a developing region by a method that applies less stress to the toner. And an image forming apparatus including the developing device.

  In order to achieve the above object, the present invention has a toner carrier having at least two types of electrode members to which different voltages are applied, and applies different voltages to the at least two types of electrode members. An electric field for hopping the toner is formed on the outer peripheral surface of the toner carrying member, and the toner in a state hopped by rotating the toner carrying member is opposed to the surface of the latent image carrying member. In the developing device that develops the latent image by being transported to and attached to the latent image on the latent image carrier, the toner carrier used is one in which irregularities are distributed in the toner carrying region on the outer peripheral surface thereof, An abutting member is provided on the upstream side of the developing region in the rotation direction of the toner carrier, and abutment members that abut on the convex portion on the outer circumferential surface of the toner carrier are supported on the outer circumferential surface of the toner carrier. Of toner, the toner on the convex portions while preventing the passage, the toner in the recess and wherein the passing.

  In the present invention, the toner carried on the concave and convex portions formed on the outer peripheral surface of the toner carrier is removed by the contact member, and only the toner that has entered the concave portion on the outer peripheral surface of the toner carrier is developed. Can be transported to. Thus, the amount of toner per unit area supplied to the development area can be controlled only by the volume of the recesses formed on the outer peripheral surface of the toner carrier and the pitch between the recesses. That is, even when the toner layer thickness on the toner carrier is uneven before entering the contact area between the outer peripheral surface of the toner carrier and the contact member, or the toner layer thickness entering the contact area is Even when it fluctuates with time, the amount of toner per unit area supplied to the development area can be controlled by the volume of the recesses and the pitch between the recesses. According to the recent processing technique, the unevenness can be formed on the outer peripheral surface of the toner carrier with high accuracy. Therefore, according to the present invention, the amount of toner per unit area supplied to the development region can be stably and highly accurate. The target amount can be controlled.

  In addition, when passing through the contact area between the outer peripheral surface of the toner carrier and the contact member, the pressure applied to the toner entering the concave portion is such that the smooth outer peripheral surface and layer of the toner carrier are the same as in a conventional developing device. It is smaller than the pressure applied to the toner when the toner is sandwiched between the thickness regulating member and passed. Therefore, according to the present invention, as compared with the conventional developing device, the toner hardly deteriorates and the life of the toner can be extended.

  When a toner carrier having irregularities formed on the outer peripheral surface as in the present invention is adopted in a conventional development method in which toner adsorbed on the surface of the toner carrier or a magnetic carrier is used for development, the toner carrier is in contact with the contact member. On the toner carrier after passing through the contact area, the area where the toner is attached (concave part) and the area where the toner is not attached (convex part) are clearly separated. Then, as a result of supplying the toner carried on the toner carrier in such a state to the developing region, image density unevenness corresponding to the unevenness on the outer peripheral surface of the toner carrier occurs. On the other hand, in the present invention, since the flare development method using the toner hopped on the outer peripheral surface of the toner carrier for development is adopted, the toner carrier after passing through the contact area with the contact member Above, the toner that has entered the concave portion hops and moves to the convex portion, and the toner is dispersed. Therefore, image density unevenness according to the unevenness on the outer peripheral surface of the toner carrier is suppressed.

  As described above, according to the present invention, it is possible to obtain an excellent effect that the amount of toner per unit area supplied to the development area can be stabilized by a method with less stress on the toner.

1 is a schematic configuration diagram illustrating a copying machine according to an embodiment. FIG. 2 is a schematic configuration diagram showing a photoreceptor and a developing device in the copier. FIG. 6 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. 4 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller when cut along a plane orthogonal to the rotation axis. 3 is a plane schematically showing irregularities formed on the outer peripheral surface of the toner carrying roller. FIG. 4 is a cross-sectional view schematically showing a cross section of a contact region between an outer peripheral surface of the toner carrying roller and a regulation blade that contacts the outer peripheral surface. FIG. 7 is a cross-sectional view schematically showing a cross section of a contact region in a conventional configuration in which a toner carrying roller outer peripheral surface is a smooth surface. 7 is a plan view schematically showing another example of unevenness formed on the outer peripheral surface of the toner carrying roller. 7 is a plan view schematically showing still another example of unevenness formed on the outer peripheral surface of the toner carrying roller. 7 is a plan view schematically showing still another example of unevenness formed on the outer peripheral surface of the toner carrying roller. 4 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. It is a graph which shows the other example of the inner side voltage applied to an inner side electrode and an outer side electrode, and an outer side voltage. It is a graph which shows the further another example of the inner side voltage applied to an inner side electrode and an outer side electrode, and an outer side voltage. It is a schematic diagram when the electric power feeding structure to an inner side electrode and an outer side electrode is cut | disconnected along a roller axis | shaft. It is a perspective view which shows the same electric power feeding structure typically. It is a schematic diagram when the electric power feeding structure to the inner side electrode and outer side electrode in the modification 1 is cut | disconnected along a roller axis | shaft. FIG. 6 is a schematic diagram when a toner carrying roller having the same power supply configuration is viewed from a direction orthogonal to the axial direction. It is a perspective view which shows the same electric power feeding structure typically. FIG. 10 is a schematic diagram showing a developing device in Modification 2. FIG. 10 is a schematic diagram illustrating a developing device according to Modification 3. FIG. 10 is a schematic configuration diagram illustrating a developing device in Modification 4 together with a photoreceptor. It is a schematic block diagram for showing the other example of the collection | recovery mechanism in the developing device. It is a schematic block diagram for showing the further another example of the collection | recovery mechanism in the developing device. It is a schematic block diagram for showing the further another example of the collection | recovery mechanism in the developing device. FIG. 10 is an enlarged configuration diagram showing a toner carrying roller of a developing device and its surrounding configuration in Modification 5. FIG. 10 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 6 is cut along a plane orthogonal to the rotation axis thereof. FIG. 3 is an explanatory diagram illustrating an outline of electric lines of force in the toner carrying roller. FIG. 10 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 7 is cut along a plane orthogonal to the rotation axis thereof. FIG. 3 is an explanatory diagram illustrating an outline of electric lines of force in the toner carrying roller. FIG. 4 is a schematic diagram when an outer electrode layer in the toner carrying roller is viewed from an outer peripheral surface side of the toner carrying roller. FIG. 10 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 8 is cut along a plane orthogonal to the rotation axis thereof. FIG. 4 is a schematic diagram when an outer electrode layer in the toner carrying roller is viewed from an outer peripheral surface side of the toner carrying roller. (A)-(c) is explanatory drawing which shows the manufacture procedure of a toner carrying roller. FIG. 10 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 9 is cut along a plane orthogonal to the rotation axis thereof. FIG. 4 is a schematic diagram when an outer electrode layer in the toner carrying roller is viewed from an outer peripheral surface side of the toner carrying roller. FIG. 10 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 10 is cut along a plane orthogonal to the rotation axis thereof. FIG. 10 is a schematic diagram for explaining another configuration example of the toner carrying roller. FIG. 10 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 11 is cut along a plane orthogonal to the rotation axis thereof. 14 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller in Modification 12 is cut along a plane orthogonal to the rotation axis thereof. FIG.

Hereinafter, an embodiment in which the present invention is applied to a copying machine which is an electrophotographic image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram showing a copying machine according to the present embodiment.
A drum-shaped photoconductor 49 as a latent image carrier is rotationally driven in the clockwise direction in the drawing. When an operator places a document (not shown) on the contact glass 90 and presses a print start switch (not shown), a first scanning optical system 93 including a document illumination light source 91 and a mirror 92 and a second including mirrors 94 and 95 are provided. The scanning optical system 96 moves to read the original image. The scanned original image is read as an image signal by an image reading element 98 disposed behind the lens 97, and the read image signal is digitized and image-processed. Then, a laser diode (LD) is driven by the signal after image processing, and after the laser light from the laser diode is reflected by the polygon mirror 99, the photoconductor 49 is scanned via the mirror 80. Prior to this scanning, the photosensitive member 49 is uniformly charged by the charging device 50, and an electrostatic latent image is formed on the surface of the photosensitive member 49 by scanning with a laser beam.

  Toner adheres to the electrostatic latent image formed on the surface of the photosensitive member 49 by the developing process of the developing device 1, thereby forming a toner image. The toner image is conveyed to a transfer position that is opposite to the transfer charger 60 as the photoconductor 49 rotates. With respect to this transfer position, the first paper supply unit 70 having the first paper supply roller 70a or the second paper supply having the second paper supply roller 71a is synchronized with the toner image on the photoconductor 49. The recording paper P is fed from the paper section 71. The toner image on the photoreceptor 49 is transferred onto the recording paper P by corona discharge of the transfer charger 60.

  The recording paper P onto which the toner image has been transferred in this manner is separated from the surface of the photoreceptor 49 by corona discharge of the separation charger 61, and then conveyed toward the fixing device 76 by the conveyance belt 75. In the fixing device 76, the fixing roller 76a is sandwiched between fixing rollers 76a including a heat source such as a halogen lamp (not shown) and a pressure roller 76b pressed against the fixing roller 76a. Thereafter, the toner image is fixed on the surface by pressurization or heating in the fixing nip, and then discharged toward a discharge tray 77 outside the apparatus.

  The transfer residual toner adhering to the surface of the photoconductor 49 that has passed the transfer position is removed from the surface of the photoconductor 49 by the cleaning device 45. The surface of the photoreceptor 49 that has been subjected to the cleaning process in this way is discharged by the charge removing lamp 44 and is prepared for the next latent image formation.

FIG. 2 is a schematic configuration diagram showing the photoreceptor 49 and the developing device 1 in the copying machine according to the present embodiment.
The drum-shaped photoconductor 49 is rotationally driven in a clockwise direction in the drawing by a driving unit (not shown). A developing device 1 having a toner carrying roller 2 as a developer carrying member is disposed on the right side of the photoconductor 49 in the drawing. The developing device 1 accommodates a first accommodating portion 13 that accommodates a first conveying screw 12 that is rotated in the clockwise direction in the drawing, and a second accommodating portion that accommodates a second conveying screw 14 that is rotated in the counterclockwise direction in the drawing. The housing portion 15 is separated from each other by a partition wall 16. Each of these accommodating portions accommodates a mixed agent in which a magnetic carrier (not shown) and a negatively chargeable toner are mixed.

  The first conveying screw 12 conveys the mixture in the first storage unit 13 from the front side in the figure to the back side in the figure while rotating and stirring the mixture in the first container 13 by its rotational drive. At this time, the toner concentration of the mixture being conveyed is detected by the toner concentration sensor 17 fixed to the bottom of the first storage unit 13. Then, the mixed agent conveyed to the vicinity of the end on the back side in the drawing enters the second accommodating portion 15 through a first communication port (not shown) provided near the end on the back side of the partition wall 16. The second storage unit 15 communicates with a magnetic brush forming unit 21 that stores a later-described toner supply roll 18 serving as a developer supply member, and the second conveying screw 14 and the toner supply roll 18 pass through a predetermined gap. Are opposed to each other with their axial directions parallel to each other. The 2nd conveyance screw 14 in the 2nd accommodating part 15 conveys the mixing agent in the 2nd accommodating part 15 from the back side in the figure to the near side in the figure, while rotating and stirring it. In this process, a part of the mixture conveyed by the second conveying screw 14 is pumped onto the toner supply sleeve 19 of the toner supply roll 18. Then, as the toner supply sleeve 19 rotates in the counterclockwise direction in the drawing, after passing through a toner supply position, which will be described later, the toner supply sleeve 19 is detached from the surface of the toner supply sleeve 19 and returned to the second storage portion 15 again. It is. Thereafter, the mixture conveyed to the vicinity of the front end in the figure by the second conveying screw 14 is first accommodated through a second communication port (not shown) provided in the vicinity of the front end in the figure of the partition wall 16. Returned to section 13.

  The toner density sensor 17 described above is a magnetic permeability sensor. The detection result of the magnetic permeability of the mixture by the toner concentration sensor 17 is sent to a control unit (not shown) as a voltage signal. Since the magnetic permeability of the mixed agent has a correlation with the K toner concentration of the mixed agent, the toner concentration sensor 17 outputs a voltage having a value corresponding to the toner concentration.

  A control unit (not shown) of the copying machine includes a RAM (Random Access Memory), in which Vtref that is a target value of the output voltage from the toner density sensor 17 is stored. Then, the output voltage value from the toner density sensor 17 is compared with Vtref in the RAM, and a toner replenishing device (not shown) is driven for a time corresponding to the comparison result. By this driving, an appropriate amount of toner is replenished from the toner replenishing port 13a into the first accommodating portion 13 with respect to the mixture whose toner density has been reduced by consumption of toner accompanying development. For this reason, the toner concentration of the mixture in the second container 15 is maintained within a predetermined range.

  The toner supply roll 18 includes a cylindrical toner supply sleeve 19 made of a non-magnetic material that is driven to rotate counterclockwise in the figure, and a magnet roller 20 that is fixedly disposed therein. The cylindrical toner supply sleeve 19 is formed by molding a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin into a cylindrical shape. Further, as shown in the figure, the magnet roller 20 includes a plurality of magnetic poles arranged in the rotational direction (N pole, S pole, N pole, S pole, N pole, S pole in order from the position directly above in the counterclockwise direction). )have. By these magnetic poles, the admixture is adsorbed on the peripheral surface of the toner supply sleeve 19, and a magnetic brush that rises along the lines of magnetic force is formed.

  The mixture pumped up by the surface of the toner supply sleeve 19 rotates in the counterclockwise direction in the drawing as the toner supply sleeve 19 rotates. Then, the toner supply sleeve 19 enters a carrying amount regulating position that is a position facing the regulating member 22 that is arranged to face the surface of the toner supply sleeve 19 with a predetermined gap. At this time, the amount of the mixed agent supported on the sleeve surface is regulated by passing through the gap between the regulating member 22 and the sleeve surface.

  On the left side of the toner supply sleeve 19 in the figure, the toner carrying roller 2 is driven to rotate counterclockwise in the figure by a driving means (not shown) while facing the surface of the toner supply sleeve 19 with a predetermined gap. As the toner supply sleeve 19 rotates, the mixture that has passed through the above-described carrying amount regulating position enters a toner supply position that is a contact position with the toner carrying roller 2. As a result, the tip of the magnetic brush made of the mixture slides on the surface of the toner carrying roller 2. The toner in the magnetic brush is supplied onto the surface of the toner carrying roller 2 due to such effects as the rubbing and the potential difference between the toner supply sleeve 19 and the toner carrying roller 2. A supply bias is applied to the toner supply sleeve 19 by a supply bias power source 24. The supply bias may be a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage as long as an electric field for moving the toner to the toner carrying roller 2 side can be formed.

  The mixture on the toner supply sleeve 19 that has passed through the toner supply position is conveyed to a position facing the second storage unit 15 as the sleeve rotates. In the vicinity of the facing position, the magnetic roller 20 is not provided with a magnetic pole, and no magnetic force attracts the mixture to the sleeve surface, so that the mixture separates from the sleeve surface and is contained in the second container 15. Return to. In this copying machine, the magnet roller 20 has six magnetic poles, but the number of magnetic poles is not limited to this. It may be 8 poles, 12 poles, or the like.

  The toner carrying roller 2 supplied with toner exposes a part of the outer peripheral surface from an opening provided in the casing 11 of the developing device 1. This exposed portion is opposed to the photoreceptor 49 with a gap of several tens to several hundreds [μm]. Thus, the position where the toner carrying roller 2 and the photosensitive member 49 are opposed to each other is the developing position in the copying machine.

  The toner supplied onto the surface of the toner carrying roller 2 passes through the gap between the regulating blade 23 as a contact member and the toner carrying roller, so that the amount of toner carried on the outer peripheral surface of the toner carrying roller 2 is regulated. Is done. The toner carried on the outer peripheral surface of the toner carrying roller 2 after being regulated by the regulating blade 23 is hopped on the surface of the toner carrying roller 2 for the reason described later, while the toner carrying roller 2 rotates. It is conveyed from the supply position toward the development position. The toner transported to the developing area adheres to the electrostatic latent image portion on the surface of the photosensitive member by a developing electric field between the toner carrying roller 2 and the electrostatic latent image on the photosensitive member 49, thereby developing the toner. Is called. The toner that has not contributed to the development is further conveyed by the rotation of the toner carrying roller 2 while hopping, and is repeatedly used.

Next, a specific configuration of the toner carrying roller 2 in the present embodiment will be described.
FIG. 3 is a schematic diagram when the toner carrying roller 2 is viewed from a direction orthogonal to the rotation axis in order to explain the electrode arrangement of the toner carrying roller 2 in the present embodiment. For convenience of explanation, the surface layer 6 and the insulating layer 5 are not shown.
FIG. 4 is a partial cross-sectional view schematically showing a cross section when the toner carrying roller 2 according to the present embodiment is cut along a plane orthogonal to the rotation axis thereof.

  The toner carrying roller 2 according to the present embodiment is configured by a hollow roller member, and an inner electrode 3a as an innermost electrode member or an inner electrode member located on the innermost periphery thereof, and on the outermost periphery side. A comb-shaped outer electrode 4a 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 3a is applied. An insulating layer 5 is provided between the inner electrode 3a and the outer electrode 4a to insulate them. Moreover, the surface layer 6 as a protective layer which covers the outer peripheral surface side of the outer electrode 4a is also provided. That is, the toner carrying roller 2 of the present embodiment has a four-layer structure of the inner electrode 3a, the insulating layer 5, the outer electrode 4a, and the surface layer 6 in order from the inner peripheral side.

  The inner electrode 3a also functions as a base of the toner carrying roller 2, 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 3a, 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 3 a is covered with the insulating layer 5. In this embodiment, the insulating layer 5 is made of polycarbonate, alkyd melamine, or the like. In the present embodiment, the thickness of the insulating layer 5 is preferably in the range of 3 [μm] to 50 [μm]. If it is smaller than 3 [μm], the insulation between the inner electrode 3a and the outer electrode 4a cannot be sufficiently maintained, and there is a high possibility that leakage occurs between the inner electrode 3a and the outer electrode 4a. Become. On the other hand, if it is larger than 50 [μm], the electric field generated between the inner electrode 3a and the outer electrode 4a is less likely to be formed outside the surface layer 6, and a strong flare electric field (external electric field) is formed outside the surface layer 6. It becomes difficult to form. In the present embodiment, the thickness of the insulating layer 5 made of melamine resin is 20 [μm]. The insulating layer 5 can be formed with a uniform film thickness on the inner electrode 3a by spraying, dipping, or the like.

  An outer electrode 4 a is formed on the insulating layer 5. In the present embodiment, the outer electrode 4a 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 4a. For example, there is a method in which a metal film is formed on the insulating layer 5 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 5 by an ink jet method or screen printing is also conceivable.

  The outer electrode 4 a and the outer peripheral surface side of the insulating layer 5 are covered with the surface layer 6. The toner is charged by contact friction with the surface layer 6 when hopping is repeated on the surface layer 6. In this embodiment, silicone, nylon (registered trademark), urethane, alkyd melamine, polycarbonate, or the like is used as a material for the surface layer 6 in order to give the toner a normal charging polarity (negative polarity in this embodiment). In this embodiment, polycarbonate is employed. Further, since the surface layer 6 also has a role of protecting the outer electrode 4a, the film thickness of the surface layer 6 is preferably in the range of 3 [μm] or more and 40 [μm] or less. If it is smaller than 3 [μm], the outer electrode 4a may be exposed due to film scraping or the like due to use over time, and may leak through the toner carried on the toner carrying roller 2 or other members contacting the toner carrying roller 2. There is. On the other hand, if it is larger than 40 [μm], the electric field generated between the inner electrode 3a and the outer electrode 4a is hardly formed outside the surface layer 6, and a strong flare electric field is formed outside the surface layer 6. It becomes difficult. In the present embodiment, the film thickness of the surface layer is 20 [μm]. The surface layer 6 can be formed by a spray method, a dipping method, or the like, similarly to the insulating layer 5.

FIG. 5 is a plan view schematically showing the unevenness formed on the outer peripheral surface of the toner carrying roller 2.
FIG. 6 is a cross-sectional view schematically showing a cross section of a contact region between the outer peripheral surface of the toner carrying roller 2 and the regulating blade 23 that contacts the outer peripheral surface.
In the present embodiment, the surface layer 6 of the toner carrying roller 2 is formed so that unevenness is distributed along the outer peripheral surface of the toner carrying roller 2. In the contact area between the outer peripheral surface of the toner carrying roller 2 having the unevenness and the regulating blade 23, the regulating blade 23 comes into contact with the convex portion 6b of the toner carrying roller 2 as shown in FIG. A gap is formed between the toner carrying roller 2 and the recess 6a. Therefore, when the toner T carried on the toner carrying roller 2 passes through the contact area as the toner carrying roller 2 rotates, the toner T carried on the convex portion 6b is prevented from passing, and the concave portion The toner T carried in 6a can pass through.

  If the outer peripheral surface of the toner carrying roller 2 is a smooth surface as shown in FIG. 7, the toner T carried on the toner carrying roller 2 is composed of the smooth outer peripheral surface of the toner carrying roller 2 and the regulating blade 23. Passing in such a way as to be sandwiched between them in the contact area. In this case, the pressure applied to the toner T when passing through the contact region is large, and the deterioration of the toner T is likely to proceed. In this case, if there is uneven thickness in the toner carrying roller rotation axis direction in the toner layer before entering the contact area, the pressure applied to the toner T in the contact area varies in the toner carrying roller rotation axis direction. As a result, toner layer thickness on the toner carrying roller 2 after passing through the contact area may cause unevenness in the direction of the rotation axis of the toner carrying roller, which may cause uneven image density. In addition, when the thickness of the toner layer entering the contact area varies with time, the pressure applied to the toner T in the contact area changes with time, so that the toner on the toner carrying roller 2 after passing through the contact area. In some cases, the toner amount deviates from the target amount, causing a decrease in image density or an increase in image density.

  In contrast, in the present embodiment, as shown in FIGS. 4 and 6, irregularities are formed in the toner carrying region on the outer peripheral surface of the toner carrying roller 2, and the regulation blade 23 is formed on the convex portion 6 b of the toner carrying roller 2. A gap is formed between the toner bearing roller 2 and the recess 6a. Thereby, when the toner T carried on the toner carrying roller 2 passes through the contact area, the toner T carried on the convex portion 6b is prevented from passing, and the toner carried in the concave portion 6a. Only T passes. The pressure applied to the toner T entering the recess 6a is the same as the pressure applied to the toner T when the toner is sandwiched between the smooth outer peripheral surface of the toner carrying roller 2 and the regulating blade 23 as in the configuration shown in FIG. Small compared. Therefore, according to the present exemplary embodiment, it is difficult for the toner to progress and the life of the toner can be extended.

  In the present embodiment, only the toner T entering the recess 6a passes through the contact area and is supplied to the development area. Accordingly, the amount of toner per unit area supplied to the development area can be controlled only by the volume of the recess 6a formed on the outer peripheral surface of the toner carrier and the pitch between the recesses. That is, even when the toner layer thickness on the toner carrying roller 2 is uneven before entering the contact area, or even when the thickness of the toner layer entering the contact area varies with time, it is supplied to the development area. The amount of toner per unit area can be controlled by the volume of the recesses and the pitch between the recesses. According to the recent processing technique, the unevenness can be formed on the outer peripheral surface of the toner carrying roller 2 with high accuracy. Therefore, in the present embodiment, the amount of toner per unit area (per unit area) supplied to the development area. The toner weight (M / A)) can be controlled to the target amount stably and with high accuracy.

  The unevenness formed on the outer peripheral surface of the toner carrying roller 2 shown in FIG. 5 is an example in which the convex portions 6 b are randomly distributed on the outer peripheral surface of the toner carrying roller 2, but is not limited thereto. For example, as shown in FIG. 8, belt-like convex portions 6 b extending along the rotation direction of the toner carrying roller are provided at predetermined intervals along the rotation axis direction of the toner carrying roller 2, and along the rotation axis direction of the toner carrying roller 2. Thus, the unevenness may be repeated in a stripe shape. If the unevenness is repeated along the rotation axis direction of the toner carrying roller as in this example, the unevenness can be formed by rolling or winding, and the productivity of the toner carrying roller 2 can be improved. Can do.

  Further, for example, as shown in FIG. 9, a belt-like convex portion may extend in a direction inclined with respect to the rotation axis direction of the toner carrying roller 2. In this case, if the convex portion is formed in a spiral shape on the outer peripheral surface of the toner carrying roller 2, the winding process is adopted and the productivity of the toner carrying roller 2 is improved.

  For example, as shown in FIG. 10, a large number of block-shaped convex portions 6 b may be regularly distributed on the outer peripheral surface of the toner carrying roller 2. In this case as well, a method such as rolling can be used, and the productivity of the toner carrying roller 2 can be improved.

  Further, the regulation blade 23 is made of a conductive material, and a voltage equivalent to the average value of the voltages applied to the inner electrode 3a and the outer electrode 4a provided on the toner carrying roller 2 is set to a predetermined power source (voltage applying means). To the regulating blade 23. In this case, the surface potential of the toner carrying roller 2 can be stabilized, the developing electric field in the developing region is stabilized, and stable developing ability can be exhibited. Specifically, the surface potential of the toner carrying roller 2 is determined by friction charging between the outer peripheral surface of the toner carrying roller 2 and the regulating blade 23, friction charging by rubbing between the hopping toner and the outer peripheral surface of the toner carrying roller 2, and the like. The fluctuation can be stabilized to the same potential as the voltage applied to the regulating blade 23, that is, the average value of the voltage applied to the inner electrode 3a and the outer electrode 4a provided on the toner carrying roller 2. .

  In the present embodiment, the electric field created between the inner electrode 3a and the outer electrode 4a, more specifically, the portion of the inner electrode 3a that does not face the outer electrode 4a (the inner side located between the comb teeth of the outer electrode 4a). The electric field created between the electrode 3a part) and the comb-teeth part of the outer electrode 4a is formed outside the surface layer 6, thereby hopping the toner on the toner carrying roller 2, thereby making the toner cloudy Let At this time, the toner on the toner carrying roller 2 reciprocates while flying between the surface layer portion facing the inner electrode 3a through the insulating layer 5 and the surface layer portion facing the outer electrode 4a adjacent thereto. You will be hopping.

  In order to stably form the 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 3a and the outer electrode 4a 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 3a and the outer electrode 4a 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.

  According to the present embodiment, since the insulating layer 5 is provided on the inner electrode 3a and the comb-shaped outer electrode 4a is formed on the insulating layer, it may cause leakage between these electrodes. There is no such interface. In addition, in the manufacturing stage of the toner carrying roller 2, the possibility that a conductive material that may cause a leak is interposed between the electrodes can be extremely reduced. Therefore, according to this embodiment, the inner electrode 3a and the outer electrode 4a can be stably and effectively insulated, 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 4a (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 4b of the outer electrode 4a is low, and it becomes difficult to hop toner stably and effectively at that location. As shown in FIG. 3, the power-supplied portion 4 b of the present embodiment is provided at both axial ends on the outer peripheral surface of the toner carrying roller 2. Therefore, in this embodiment, when the electrode width of the outer electrode 4a is larger than 120 [μm], the flare electric field at the axial center of the toner carrying roller 2 is relatively lower than the flare electric field at both axial ends. 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 of the outer electrode 4a (the distance between the comb tooth portions) is the same as 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 3a converge on the outer electrode 4a before coming out of the outer surface 6, and the flare electric field formed on the outer surface 6 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 the present embodiment, the electrode pitch of the outer electrode 4 a is set to be constant over the circumferential direction of the toner carrying roller 2. By making the electrode pitch constant, the flare electric field created between the inner electrode 3 a and the outer electrode 4 a becomes substantially uniform over the circumferential direction on the toner carrying roller 2. 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 3a and the outer electrode 4a will be described.
As shown in FIG. 3, an inner voltage as a first voltage and an outer voltage as a second voltage are applied to the inner electrode 3a and the outer electrode 4a on the toner carrying roller 2 from pulse power sources 25A and 25B, respectively. . A rectangular wave is most suitable for the inner voltage and the outer voltage applied by the pulse power supplies 25A and 25B. However, not limited to this, for example, a sine wave or a triangular wave may be used. Further, in this embodiment, the electrodes for forming the flare electrode have a two-phase configuration of the inner electrode 3a and the outer electrode 4a, and voltages having a phase difference π are applied to the electrodes 3a and 4a, respectively. The

FIG. 11 is a graph showing an example of the inner voltage and the outer voltage applied to the inner electrode 3a and the outer electrode 4a, respectively.
In this embodiment, each voltage is a rectangular wave, and the inner voltage and the outer voltage applied to the inner electrode 3a and the outer electrode 4a, 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 3a and the outer electrode 4a. An electric field is generated between the electrodes due to the potential difference, and the toner hops on the surface layer 6 by the flare electric field formed outside the surface layer 6 in the electric field. In the present embodiment, Vpp is preferably in the range of 100 [V] to 2000 [V]. If Vpp is less than 100 [V], a sufficient flare electric field cannot be formed on the surface layer 6 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.

  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].

FIG. 12 is a graph showing another example of the inner voltage and the outer voltage applied to the inner electrode 3a and the outer electrode 4a.
In this example, an inner voltage similar to that shown in FIG. 11 is applied to the inner electrode 3a, but a DC voltage is applied to the outer electrode 4a. In this case, the potential difference between the electrodes is Vpp / 2. Therefore, a suitable range of Vpp in this example is 200 [V] or more and 4000 [V] or less. According to this example, it is not necessary to consider the phase difference between the inner electrode 3a and the outer electrode 4a, and the power supply cost is reduced.

FIG. 13 is a graph showing still another example of the inner voltage and the outer voltage applied to the inner electrode 3a and the outer electrode 4a.
In this example, an inner voltage similar to that shown in FIG. 11 is applied to the outer electrode 4a, but a DC voltage is applied to the inner electrode 3a. Also in this case, the potential difference between the electrodes is Vpp / 2. Therefore, a suitable range of Vpp in this example is 200 [V] or more and 4000 [V] or less. Also in this example, it is not necessary to consider the phase difference between the inner electrode 3a and the outer electrode 4a, and the power supply cost is reduced.

FIG. 14 is a schematic diagram when the power supply configuration to the inner electrode 3a and the outer electrode 4a in this embodiment is cut along the roller axis.
FIG. 15 is a perspective view schematically showing the power supply configuration. In the power supply configuration to the inner electrode 3a and the outer electrode 4a in the present embodiment, the inner electrode 3a is integrated with the roller shaft of the toner carrying roller 2, and the end surface of the roller shaft serves as the power supplied portion 3b. A power supply brush 7 serving as a first power supply member connected to the pulse power supply 25A is in contact with the power-supplied portion 3b formed by the end surface of the roller shaft. On the other hand, the surface layer 6 is not provided at both end portions of the outer peripheral surface of the toner carrying roller 2, and both end portions of the outer electrode 4a on the outer peripheral surface of the toner carrying roller 2 are exposed. It becomes. A power feeding roller 8 as a second power feeding member connected to the pulse power supply 25B is in contact with the power-supplied portion 4b configured by the exposed surface. The power supply roller 8 is rotatably supported and rotates along with the rotation of the toner carrying roller 2 while being in contact with the power-supplied portion 4b.

  In the present embodiment, two power supply rollers 8 that are second power supply members for applying an external voltage to the outer electrode 4a are provided, but may be one or three or more. . If there are a plurality of second power supply members for applying an external voltage to the outer electrode 4a, power can be supplied by another second power supply member even if some of the second power supply members have poor power supply due to poor contact. Therefore, stable power feeding can be performed.

  Further, as in the present embodiment, a part of the outer electrode 4a is exposed on the outer peripheral surface of the toner carrying roller 2, and the exposed portion is used as a power-supplied portion 4b to supply power by bringing a second power supply member into contact therewith. Is used, the power-supplied portion 4b is positioned on the outer side in the axial direction with respect to the developing width on the toner carrying roller 2 (region width on which the electrostatic latent image can be formed on the photosensitive member). Is desired. This is because when the power-supplied portion 4b is positioned within the development width, the toner crushed between the power supply roller 8 and the power-supplied portion 4b contributes to development, and development failure occurs in that portion. . More preferably, the power-supplied portion 4b is desired to be positioned on the outer side in the axial direction with respect to the toner supply width on the toner carrying roller 2 (region width to which toner is supplied from the toner supply sleeve 19). This is because when the power-supplied part 4b is positioned within the toner supply width, a large amount of toner is interposed between the power supply roller 8 and the power-supplied part 4b, and power supply failure is likely to occur. In the present embodiment, the power-supplied part 4 b is configured to be positioned on the outer side in the axial direction than the toner supply width on the toner carrying roller 2. Furthermore, in this embodiment, a toner seal (not shown) is provided on the axially central side of each power-supplied portion 4b located at both ends of the roller so that the toner within the toner supply width does not adhere to the power-supplied portion 4b. .

  In the present embodiment, the power feeding roller 8 that rotates along with the power-supplied portion 4b is used as the second power feeding member. However, the present invention is not limited thereto, and for example, a conductive brush or a conductive leaf spring is used. Also good. In addition, when using the 2nd electric power feeding member which slides with respect to the to-be-powered part 4b like a conductive brush, an electroconductive leaf | plate spring, etc., in order to suppress abrasion of the contact part with the to-be-powered part 4b, it is electroconductive. Fill with grease. In the present embodiment, the case where the power-supplied portion of the inner electrode 3a is the end surface of the roller shaft has been described. However, the present invention is not limited thereto, and for example, the peripheral surface of the roller shaft or the end surface of the roller main body may be used. .

[Modification 1]
Next, a modified example of the power feeding configuration to the inner electrode 3a and the outer electrode 4a (hereinafter, this modified example is referred to as “modified example 1”) will be described.
FIG. 16 is a schematic diagram when the power supply configuration to the inner electrode 3a and the outer electrode 4a in the first modification is cut along the roller axis.
FIG. 17 is a schematic diagram of a toner carrying roller having the same power supply configuration as viewed from a direction orthogonal to the axial direction.
FIG. 18 is a perspective view schematically showing the power supply configuration.

  In the first modification, the power supply configuration for the inner electrode 3a is configured such that the end surface of the roller shaft becomes the power-supplied portion 3b, as in the above-described embodiment, and the power supply brush 7 is applied to the power-supplied portion 3b. It touches. On the other hand, in the power supply configuration for the outer electrode 4a, the outer electrode 4a is drawn out to the circumferential surface of the roller shaft, and the drawn portion is used as a power supply portion 4b. The insulating layer 5 is similarly drawn out to the roller shaft peripheral surface, thereby ensuring insulation between the inner electrode 3a and the outer electrode 4a on the roller shaft peripheral surface. A power supply brush 8 'serving as a second power supply member connected to the pulse power supply 25B is in contact with the power supplied portion 4b on the roller shaft peripheral surface.

  In addition to the power supply configuration illustrated in the first modification, for example, the roller shafts of the toner carrying roller 2 are electrically divided from each other, and the inner electrode 3a and the outer electrode 4a are electrically connected to one of the shafts. A configuration in which a voltage is applied to each of the inner electrode 3a and the outer electrode 4a through the shaft is conceivable.

[Modification 2]
Next, a modified example of the configuration for supplying toner to the toner carrying roller 2 (hereinafter, this modified example is referred to as “modified example 2”) will be described.
FIG. 19 is a schematic diagram illustrating a developing device according to the second modification.
In the second modification, toner is supplied to the toner carrying roller 2 without using a magnetic carrier. Specifically, the developing device 1 according to the second modification is driven to rotate in the counterclockwise direction in the drawing by the first storage portion 13 that stores the first conveying screw 12 that is driven to rotate in the clockwise direction in the drawing. And a second accommodating portion 15 that accommodates the second conveying screw 14, and both accommodating portions are partitioned by a partition wall 16. Each of these storage portions stores negatively chargeable toner (not shown). The toner is circulated and conveyed through the first storage unit 13 and the second storage unit 15 by the rotational drive of the first transport screw 12 and the second transport screw 14. During this conveyance, the toner is triboelectrically charged by being rubbed from the first conveyance screw 12 and the second conveyance screw 14. The toner in the second container 15 thus frictionally charged is electrostatically attracted onto the toner supply roll 18 ′ to which the supply bias is applied by the supply bias power supply 24. The supply bias may be a DC voltage or an AC voltage, or may be a bias in which an AC voltage is superimposed on the DC voltage. The toner adsorbed on the toner supply roll 18 ′ is conveyed to the supply position after the carrying amount is regulated by the regulating member 22. Then, the toner conveyed to the supply position is supplied onto the surface of the toner carrying roller 2 under the action of the potential difference between the toner supply roll 18 ′ and the toner carrying roller 2. After that, since it is the same as that of the said embodiment, description is abbreviate | omitted.

[Modification 3]
Next, another modification of the configuration for supplying toner to the toner carrying roller 2 (hereinafter, this modification will be referred to as “Modification 3”) will be described.
FIG. 20 is a schematic diagram illustrating a developing device according to the third modification.
In the third modification, as in the second modification, the toner is supplied to the toner carrying roller 2 without using the magnetic carrier, but the toner is directly supplied to the toner carrying roller 2 without using the toner supply roll 18 ′. To do. Specifically, in the third modification, a sponge roller 18 ′ is provided in the toner storage portion 15 ′, and the surface of the sponge roller 18 ′ is brought into contact with the surface of the toner carrying roller 2. As a result, the toner adhering to the surface of the sponge roller 18 ′ in the toner accommodating portion 15 ′ is rubbed and charged at the contact portion with the surface of the toner carrying roller 2, thereby electrostatically toner. It is supplied onto the carrier roller 2. In the third modification, the sponge roller 18 ′ is driven to rotate in the trailing direction with respect to the toner carrying roller 2, but it may be in the counter direction. In the case of the third modification, the amount of toner supplied to the toner carrying roller 2 can be controlled by the supply bias applied by the supply bias power supply 24 ′ connected to the sponge roller 18 ′. This supply bias may be a DC voltage or an AC voltage, or may be a bias in which an AC voltage is superimposed on the DC voltage.

[Modification 4]
Next, a modified example of the developing device provided with a collecting mechanism 30 as a collecting unit that collects toner that has not contributed to development from the toner carrying roller 2 (hereinafter, this modified example is referred to as “modified example 4”) will be described. To do.
FIG. 21 is a schematic configuration diagram illustrating the developing device according to the fourth modification together with the photoconductor 49.
The basic configuration of the developing device according to the fourth modification is the same as that of the above embodiment, except that the collection mechanism 30 is provided and the inner wall of the casing 11 located below the toner carrying roller 2 and the toner supply roll 18. However, it is the structure which is mainly different from the point which inclines downward toward the 2nd accommodating part 15 which accommodates the 2nd conveying screw 14. FIG. Only this different configuration will be described below.

  In the fourth modification, the recovery mechanism 30 includes a recovery plate 31 disposed so as to face the outer peripheral surface of the toner carrying roller 2, a vibrator 32 disposed so as to contact the recovery plate 31, and the recovery plate 31. And a recovery power source 33 for applying a predetermined voltage to the power source. An electric field is formed between the toner carrying roller 2 and the collecting plate 31 in such a direction that electrostatically moves the negatively charged toner from the toner carrying roller 2 toward the collecting plate 31. As a result, the toner that has not contributed to development in the development area moves from the toner carrying roller 2 toward the collection plate 31 in the collection area where the collection plate 31 and the toner carrying roller 2 face each other. The toner adhering to the recovery plate 31 is shaken off from the recovery plate 31 by vibrating the recovery plate 31 by the vibrator 32. The shaken toner moves on the inner wall surface of the casing 11 and is returned to the second storage unit 15, and is circulated and conveyed through the first storage unit 13 and the second storage unit 15 again.

FIG. 22 is a schematic configuration diagram for illustrating another example of the recovery mechanism 30.
As shown in FIG. 22, a configuration using a collection roller 34 can be employed as the collection mechanism 30. Specifically, the collection mechanism 30 includes a collection roller 34 disposed so as to face the outer peripheral surface of the toner carrying roller 2, a cleaning blade 35 disposed so as to contact the collection roller 34, and the collection roller 34. And a recovery power source 33 for applying a predetermined voltage to the power source. An electric field is formed between the toner carrying roller 2 and the collecting roller 34 in such a direction that electrostatically moves the negatively charged toner from the toner carrying roller 2 toward the collecting roller 34. As a result, toner that has not contributed to development in the development area moves from the toner carrying roller 2 toward the collection roller 34 in the collection area where the collection roller 34 and the toner carrying roller 2 face each other. The toner adhering to the collection roller 34 is scraped off by the cleaning blade 35. The toner that has been scraped off moves on the inner wall surface of the casing 11 and is returned into the second storage unit 15, and is circulated and conveyed through the first storage unit 13 and the second storage unit 15 again.

FIG. 23 is a schematic configuration diagram for illustrating still another example of the recovery mechanism 30.
As shown in FIG. 23, a configuration using a brush roller 36 can be employed as the collection mechanism 30. Specifically, the recovery mechanism 30 includes a brush roller 36 disposed so as to be in contact with the outer peripheral surface of the toner carrying roller 2, a flicker 37 disposed so as to be in contact with the brush roller 36, a brush The recovery power source 33 is configured to apply a predetermined voltage to the roller 36. An electric field is formed between the toner carrying roller 2 and the brush roller 36 in such a direction that electrostatically moves the negatively charged toner from the toner carrying roller 2 toward the brush roller 36. As a result, toner that has not contributed to development in the development area moves from the toner carrying roller 2 toward the brush roller 36 in the collection area where the brush roller 36 and the toner carrying roller 2 face each other. The toner adhering to the brush roller 36 is removed by the flicker 37. The toner that has been wiped off moves on the inner wall surface of the casing 11 and is returned into the second storage unit 15, and is circulated and conveyed through the first storage unit 13 and the second storage unit 15 again.

FIG. 24 is a schematic configuration diagram for illustrating still another example of the recovery mechanism 30.
As shown in FIG. 24, a configuration using a suction pump 40 can be employed as the recovery mechanism 30. Specifically, the recovery mechanism 30 includes a suction nozzle 38 disposed so as to face the outer peripheral surface of the toner carrying roller 2, an inlet end connected to the suction nozzle 38, and an outlet end 41 a at the first conveying screw 12. And a suction pump 40 for sucking and conveying the toner from the suction nozzle 38 to the outlet end 41a of the duct 41. Further, a seal 39 is provided downstream of the suction nozzle 38 in the direction of surface movement of the toner carrying roller 2. The seal 39 is in contact with the surface of the toner carrying roller 2. The toner that has not contributed to the development in the development area is sucked into the suction nozzle 38 by the air flow generated by the suction pump 40 in the collection area where the toner carrying roller 2 and the suction nozzle 38 face each other, and the duct 41 Then, it is returned from the outlet end 41a into the first accommodating portion 13 and is circulated and conveyed through the first accommodating portion 13 and the second accommodating portion 15 again. Note that the toner that has passed through the collection region without getting on the air flow is blocked by the seal and is not conveyed downstream as it is.

[Modification 5]
Next, a modification of the developing device provided with a pre-development toner collecting means for collecting the toner adhering to the non-image part (background part) on the photoconductor 49 in the development area upstream of the development area (hereinafter, this modification) Will be referred to as “Modification 5”.
FIG. 25 is an enlarged configuration diagram showing the toner carrying roller 2 of the developing device and its surrounding configuration in the fifth modification. In addition, in this figure, illustration of the control blade 23 is abbreviate | omitted for description.
In FIG. 25, a region denoted by Ar0 indicates a toner supply region in which the toner carrying roller 2 and a magnetic brush (not shown) formed on the surface of the toner supply sleeve 19 of the toner supply roll 18 rub against each other. . An area denoted by reference symbol Ar2 indicates a development area. An area denoted by Ar1 is a pre-development transport area as an area before passing into the development area Ar2 after passing through the toner supply area Ar0 among all areas in the surface movement direction of the toner carrying roller 2. Show. The contact area with which the restriction blade 23 contacts is present in the pre-development transport area Ar1. An area denoted by Ar3 indicates a post-development conveyance area as an area before passing through the development area Ar2 and before entering the toner supply area Ar0.

  The developing area Ar2 is an area where the photoconductor 49 and the toner carrying roller 2 face each other, and the photoconductor 49 is very close to the toner carrying roller 2 due to its curvature. The length of the toner carrying roller 2 in the developing area Ar2 in the surface movement direction can be measured as follows. That is, the solid image formed on the photoconductor 49 is developed while photographing the behavior of the toner in the developing area Ar2 and the vicinity in the vicinity thereof with a high-magnification high-speed camera. Then, the position where the toner particles adhering to the upstream end of the solid image in the moving direction of the photosensitive member surface hopped on the surface of the toner carrying roller 2 and the toner particles adhering to the downstream end of the solid image in the rotating direction of the photosensitive member are The distance from the last hopped position on the surface of the toner carrying roller 2 is measured. This distance is the length of the developing region Ar2 in the roller rotation direction.

  Each toner that hops in the pre-development transport area Ar1 gradually approaches the development area Ar2 as the toner carrying roller 2 rotates, and includes reversely charged toner. Also included is a reversely charged toner that is larger than the average toner charge amount on the normal polarity side. When these reversely charged toner and high charge amount toner are conveyed to the developing area Ar2, they adhere to the non-image area (background area) of the photoreceptor 49 and cause background staining.

  Therefore, in the fifth modification, a pre-development toner collecting means for collecting the reversely charged toner and the high charge amount toner out of the toner hopping on the surface of the toner carrying roller 2 in the pre-development conveyance area Ar1 is provided. Yes. This pre-development toner collecting means has a pre-development counter electrode 42 that opposes the pre-development transport area Ar <b> 1 through a predetermined gap in the entire rotation area on the surface of the toner carrying roller 2. . Further, it also has a pre-development recovery bias power source 43 as voltage supply means for supplying a pre-development recovery bias to the pre-development counter electrode 42.

  The pre-development counter electrode 42 is at least the surface facing the toner carrying roller 2 so that the gap with the toner carrying roller 2 is substantially uniform from the upstream end to the downstream end in the rotation direction of the toner carrying roller 2. Is curved. This gap is set to the same value as the developing gap, which is the minimum gap between the photoreceptor 49 and the toner carrying roller 2 in the developing area Ar2. The pre-development recovery bias power supply 43 outputs a pre-development counter bias having a DC voltage having the same polarity and the same value as the background portion (uniform charging potential) of the photoreceptor 49. That is, by applying the pre-development counter bias, the potential of the pre-development counter electrode 42 has the same polarity and the same value as the background portion potential on the photoreceptor 49.

  The above-mentioned pre-development toner collecting means has a control unit (not shown) for controlling on / off of the pre-development recovery bias output from this power supply in addition to the pre-development counter electrode 42 and the pre-development recovery bias power supply 43. During the developing operation (a state in which toner that can contribute to the development of the electrostatic latent image is being conveyed in the pre-development conveyance area Ar1 and the development area Ar2), the pre-development recovery bias with respect to the pre-development counter electrode 42. Is applied. In such a configuration, among countless toners that are hopped in the pre-development transport area Ar1, a scumming toner that adheres to the background of the photoreceptor 49 in the developing area Ar2 and causes scumming, that is, a reversely charged toner. The high charge amount toner is selectively attached to the counter electrode 42 before development. Thus, the background toner is selectively separated from the toner conveyed in the pre-development conveyance area Ar1.

  When the developing operation (continuous developing operation at the time of continuous printing) is completed, the controller controls the output voltage from the pre-development recovery bias power supply 43 from the pre-development recovery bias according to the control signal, and charges the toner more than this. Switch to a discharge bias that is large on the polarity side (large on the negative side in this example). As a result, the reversely charged toner or the high charge amount toner adhering to the counter electrode 42 before development separates from the counter electrode 42 before development and is discharged onto the surface of the toner carrying roller 2. Then, after passing through the developing area Ar2 and the post-development transport area Ar3, the toner is collected in the magnetic brush in the toner supply area Ar0.

  Note that it is preferable to apply a large alternating voltage across the plus side and the minus side to the discharge bias for the central value of the voltage applied to the electrode of the toner carrying roller 2. As a result, the force for reciprocating the toner existing between the toner carrying roller 2 and the pre-development recovery bias power supply 43 acts on the toner, and the toner can be easily released from the adhesive force with the predevelopment recovery bias power supply 43. Thus, the toner on the pre-development recovery bias power supply 43 can be restrained by the flare electric field generated between the electrodes of the toner carrying roller 2 and can be efficiently conveyed as the toner carrying roller 2 rotates.

  In the configuration in which a supply bias is applied to the toner supply rolls 18 and 18 ′ and toner is electrostatically supplied to the toner carrying roller 2, a discharge bias is applied to the pre-development counter electrode 42 to apply the pre-development counter electrode 42. When the reversely charged toner or the high charge amount toner adhering to the toner is returned to the toner carrying roller 2, it is preferable to stop applying the supply bias to the toner supply rolls 18 and 18 '. In this case, the reversely charged toner or the high charge amount toner can be returned onto the toner carrying roller 2 having a small toner adhesion amount.

  The method of removing the reversely charged toner and the high charge amount toner adhering to the counter electrode 42 before development from the counter electrode 42 before development is not limited to the method of applying the discharge bias to the counter electrode 42 before development. For example, the reversely charged toner or the high charge amount toner adhering to the pre-development counter electrode 42 is scraped off with a brush brush for removal, or the pre-development counter electrode 42 is scanned in the axial direction by a removal member with a blade. A method for removing adhering reversely charged toner or high charge amount toner can be considered.

  The high charge amount toner conveyed on the pre-development conveyance area Ar1 has a larger charge amount than other toners, and therefore hops higher than the other toners. Then, when the maximum level is reached by hopping, the toner cloud composed of a large amount of toner is positioned below itself, and the repulsive force may be scattered to the extent that the restraining force due to the electric field on the toner carrying roller 2 does not reach. . By providing the pre-development counter electrode 42, it is possible to prevent such scattering of the high charge amount toner.

  As the pre-development counter electrode 42, it is desirable to use a surface of an electrode layer made of a conductive material such as metal (a surface facing the toner carrying roller 2) covered with an insulating layer 5 made of an insulating material. According to this configuration, it is possible to avoid charge injection into the toner and leakage of toner charge to the electrode layer due to direct contact between the toner and the conductive surface of the counter electrode 42 before development.

  Further, as the counter electrode 42 before development, the length in the direction orthogonal to the roller rotation direction on the surface facing the toner carrying roller 2 is the length in the same direction of the surface facing the counter electrode 42 before development in the toner carrying roller 2. More than that is used. In such a configuration, it is possible to separate the reversely charged toner and the high charge amount toner in the entire region in the orthogonal direction with respect to the toner hopped in the pre-development conveyance region Ar1.

  In addition, as the counter electrode 42 before development, an electrode in which the length in the roller rotating direction on the surface facing the toner carrying roller 2 is equal to or longer than the length in the roller rotating direction of the developing area Ar2 is used. In such a configuration, unlike the case where the length of the development area Ar2 is less than the length in the roller rotation direction, the toner is transported immediately below the counter electrode 42 before development for a time longer than the development area passage time, so that the ground in the development area Ar2 can be obtained. It is possible to reliably separate the reversely charged toner and the high charge amount toner that become dirty toner.

  In the pre-development transport area Ar1, the toner hopping condition in the area where the toner carrying roller 2 and the pre-development facing electrode 42 face each other (hereinafter, this area is referred to as a pre-development collection area) Set the same. With such a configuration, it is possible to avoid the deterioration of separation / collection accuracy of the reversely charged toner and the high charge amount toner caused by making the toner hopping condition in the pre-development collection area different from that in the development area Ar2. Here, the toner hopping conditions are a combination of the widths of the electrodes 3a and 4a, the arrangement pitch of the electrodes, the characteristics of the pulse voltage applied to each electrode, and the thicknesses of the insulating layer 5 and the surface layer 6.

[Modification 6]
Next, a modified example of the outer electrode 4a (hereinafter, this modified example is referred to as “modified example 6”) will be described.
Conventionally, most of the toner on each outer electrode 4a is caused by a flare electric field between two outer electrodes adjacent to each outer electrode 4a (the inner electrode 3a not facing the outer electrode 4a faces each other). Part of the inner electrode facing portion), and most of the toner on each inner electrode facing portion is exposed to two inner electrodes facing each other by the flare electric field. The width of the outer electrode 4a (the length in the direction of movement of the toner carrying roller) and the width of the inner electrode facing portion are set in accordance with the strength of the flare electric field so that the outer electrode 4a can be moved to any position.

  Here, the width of the outer electrode 4a and the width of the inner electrode facing portion are equal (strictly, some non-uniformity occurs due to manufacturing errors), and the inner electrode 3a and the outer electrode 4a have equal potentials. If so, a flare electric field with little unevenness can be formed on the toner carrying roller 2. In such a case, as long as no other external force acts on the toner hopping on the toner carrying roller 2, the toner on the toner carrying roller 2 is distributed almost uniformly over the entire outer peripheral surface where the inner electrode 3a and the outer electrode 4a face each other. In this state, you can hop. However, the inner electrode 3a and the outer electrode 4a are not at the same potential, and a potential gradient due to a manufacturing error occurs in the surface movement direction of the toner carrying roller 2 in each of the electrodes 3a and 4a. In some cases, a flare electric field that is biased in the surface movement direction is formed. In this case, the toner hopping on the toner carrying roller 2 moves so as to be biased in the surface movement direction of the toner carrying roller 2 so as to move while hopping the outer electrode 4a and the inner electrode facing portion according to the potential gradient. . As a result, a large amount of toner is unevenly distributed on the toner carrying roller 2, and a large amount of toner unevenness (low frequency unevenness) occurs on the toner carrying roller 2.

In some cases, an airflow generated near the surface of the toner carrying roller 2 acts on the toner, and an external force that moves the toner to the upstream side or the downstream side in the surface movement direction of the toner carrying roller 2 may be generated. For example, when an external force is generated downstream of the toner carrying roller 2 in the surface movement direction, a lot of toner hopping on the toner carrying roller 2 is affected by the flare electric field and the external force. Move downstream. Therefore, a large amount of toner moves so as to deviate in the surface movement direction of the toner carrying roller 2 so as to walk downstream in the toner carrying roller surface movement direction while hopping the outer electrode 4a and the inner electrode facing portion.
As a result, a large amount of toner is unevenly distributed on the toner carrying roller 2, and a large amount of toner unevenness (low frequency unevenness) occurs on the toner carrying roller 2. Such unevenness causes image density unevenness.

FIG. 26 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 according to Modification 6 when cut along a plane orthogonal to the rotation axis.
FIG. 27 is an explanatory diagram illustrating an outline of electric lines of force.
In the sixth modification, the width X of the outer electrode 4a is manufactured to be uniform, but the width of the inner electrode facing portion is alternately short width Y1 and long width Y2 in the surface movement direction of the toner carrying roller 2. Is manufactured to exist. In the width of the inner electrode facing portion, the difference (Y2-Y1) between the short width Y1 and the long width Y2 is a difference that exceeds the range of manufacturing error when attempting to uniformly manufacture the width of the inner electrode facing portion. In such a configuration, even when a force for moving the toner to the upstream side or the downstream side in the movement direction of the surface of the toner carrying roller is generated due to a potential gradient or an air flow, the toner on the toner carrying roller 2 as described below. Thus, it is possible to prevent the toner from being unevenly distributed.

  That is, when the above force is generated, most of the toner hopping on the toner carrying roller 2 tends to move in the direction of the force along the surface of the toner carrying roller. Here, when focusing on one outer electrode 4a, as shown in FIG. 27, each flare electric field (electric field formed on the outer side of the surface layer 6) formed between two adjacent inner electrode facing portions as shown in FIG. ) Varies relatively depending on the width of the inner electrode facing portion. In other words, the flare electric field formed between the long width Y2 and the inner electrode facing portion is stronger than the flare electric field formed between the short width Y1 and the inner electrode facing portion. And the electric field for flare formed between the inner electrode opposing part of long width Y2 made the width | variety of an inner electrode opposing part equal, if the voltage applied to the inner electrode 3a and the outer electrode 4a is the same The electric field is stronger than in the case. Therefore, even when the above-described force is generated, a large amount of toner hopped from the outer electrode 4a to the inner electrode facing portion having the long width Y2 adjacent in the direction of the force is returned to the original outer electrode 4a again. It becomes possible. As a result, the toner that has moved from the outer electrode 4a to the inner electrode facing portion of the long width Y2 adjacent in the direction of the force is less likely to travel to the outer electrode 4a adjacent in the direction of the force.

  As described above, in the sixth modification, the inner electrode facing portion having the long width Y2 serves as a barrier that prevents the movement of the toner that is moved in the direction of the force under the action of the force as described above. Further, it is possible to suppress the toner from being unevenly distributed on the toner carrying roller 2. Therefore, it is possible to suppress the occurrence of a large amount of toner unevenness (low frequency unevenness) on the toner carrying roller 2 and to suppress image density unevenness. In the sixth modification, the inner electrode facing portion having a longer width Y2 is adjacent to the inner electrode facing portion having a shorter width Y1 than the amount of toner existing between the inner electrode facing portion having a shorter width Y1 and the outer electrode 4a adjacent thereto. Since the amount of toner existing near the outer electrode 4a is larger, the toner amount unevenly occurs on the toner carrying roller 2 when viewed microscopically. However, such unevenness is a high-frequency unevenness with a very short period, so that it is difficult to affect the image density, and even if the image density is affected, it does not become an unevenness that can be detected by humans. Does not affect the image quality.

  In the sixth modification, the long width Y2 of the inner electrode facing portion is preferably set to 2 to 5 times the short width Y1 of the inner electrode facing portion. If it is less than 2 times, the flare electric field formed between the long width Y2 and the inner electrode facing part cannot be a sufficiently strong electric field, and cannot sufficiently serve as the barrier. The effect of suppressing uneven image density is low. On the other hand, when it exceeds 5 times, the toner existing in the center of the inner electrode facing portion of the long width Y2 cannot move onto the adjacent outer electrode 4a, and it becomes difficult to efficiently cloud the toner. In addition, it is preferable that the short width Y1 of the inner electrode facing portion is approximately the same as the electrode width of the outer electrode 4a. In the sixth modification, the electrode width of the outer electrode 4a is set to 40 [μm], the short width Y1 of the inner electrode facing portion is set to 40 [μm], and the long width Y2 of the inner electrode facing portion is set to 120 [μm]. Yes.

  In the sixth modification, the case has been described in which the width X of the outer electrode 4a is made uniform and the width of the inner electrode facing portion is made unequal, but conversely, the width X of the outer electrode 4a is made unequal, The same effect can be obtained even when the widths of the inner electrode facing portions are made uniform. Further, in the sixth modification, the width of the inner electrode facing portion is not uniform so that the short width Y1 and the long width Y2 exist alternately in the surface movement direction of the toner carrying roller 2, but the unevenness is not uniform. The method is not limited. For example, it may be unequal such that one long width Y2 exists after two or more short widths Y1 continue. Moreover, you may make it become three or more types of widths.

[Modification 7]
Next, another modified example of the outer electrode 4a (hereinafter, this modified example is referred to as “modified example 7”) will be described.
FIG. 28 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 in Modification 7 when cut along a plane orthogonal to the rotation axis.
FIG. 29 is an explanatory diagram illustrating an outline of electric lines of force.
In this modified example 7, after the insulating layer 5 is provided on the outer peripheral surface side of the inner electrode 3a, the outer electrode layer mainly composed of aluminum, copper, silver or the like is provided on the entire insulating layer 5. This outer electrode layer is obtained by dispersing insulating particles 4c in aluminum, copper, silver or the like, and the metal portion thereof becomes the outer electrode 4a. The average particle diameter of the insulating particles 4c is larger than the layer thickness of the outer electrode layer. As a result, as shown in FIG. 29, the lines of electric force from the inner electrode 3a come out to the outside of the surface layer 6 through the insulating particles 4c, and an electric field for flare can be efficiently formed outside the surface layer 6. Examples of the insulating particles 4c include resins such as polyester and epoxy, and electrical insulators such as glass beads. Further, the method for forming the outer electrode layer on the insulating layer 5 is not particularly limited. For example, there is a method in which a conductive paste in which insulating particles 4c are dispersed is directly formed on the insulating layer 5 by screen printing. Can be mentioned. The layer thickness of the outer electrode layer is preferably several [μm] to several tens [μm]. In this modification 7, it is set to 5 [μm].

FIG. 30 is a schematic diagram when the outer electrode layer is viewed from the outer peripheral surface side of the toner carrying roller 2.
In this modified example 7, the surface area of the formed outer electrode 4a can be controlled by changing the volume ratio of the insulating particles 4c to the entire outer electrode layer, and the strength of the flare electric field can be controlled. is there. In Modification Example 7, if the volume ratio of the insulating particles 4c to the entire outer electrode layer is in the range of 0.2 to 0.8, the toner can be sufficiently clouded. When the volume ratio of the insulating particles 4c to the entire outer electrode layer is larger than 0.8, a large number of float electrodes exist because the insulating particles 4c occupy most of the outer electrode layer. That is, the voltage applied to the outer electrode layer is distributed throughout the outer electrode layer through the outer electrode 4a that is not divided by the insulating particles 4c, but when the insulating particles 4c occupy most of the outer electrode layer, Many portions of the outer electrode 4a are divided by the insulating particles 4c to be in an electrically floating state. Although the float electrode may exist even if the volume ratio of the insulating particles 4c to the entire outer electrode layer is 0.8 or less, the formation of the flare electric field is not greatly affected if the number is small. On the other hand, when the volume ratio of the insulating particles 4c to the entire outer electrode layer is smaller than 0.2, most of the lines of electric force from the inner electrode 3a converge on the outer electrode 4a before coming out of the surface layer 6. Therefore, the flare electric field formed outside the surface layer 6 is weakened. In the seventh modification, the volume ratio of the insulating particles 4c to the entire outer electrode layer is set to 0.4.

  According to the present modified example 7, the width of the outer electrode 4a becomes uneven, and the interparticle distance of the insulating particles 4c (corresponding to the width of the inner electrode facing portion in the modified example 6) also becomes uneven. As a result, as in the above-described modification example 6, locally strong flare electric fields can be dispersedly formed on the toner carrying roller 2. Thereby, even when a force for moving the toner in a specific direction is generated due to a potential gradient or an air flow, it is possible to suppress the toner from being unevenly distributed on the toner carrying roller 2. Moreover, in the above modified example 6, only the force in the direction along the surface movement direction of the toner carrying roller 2 can be dealt with, but according to this modified example 7, the direction along the axial direction of the toner carrying roller 2, etc. This is more advantageous than Modification 6 in that it can cope with forces in other directions.

[Modification 8]
Next, still another modified example of the outer electrode 4a (hereinafter, this modified example is referred to as “modified example 8”) will be described.
FIG. 31 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 in Modification 8 when cut along a plane orthogonal to the rotation axis.
FIG. 32 is a schematic diagram when the outer electrode layer is viewed from the outer peripheral surface side of the toner carrying roller 2.
Also in the present modified example 8, after the insulating layer 5 is provided on the outer peripheral surface side of the inner electrode 3a (FIG. 33A), the outer electrode layer is provided on the entire insulating layer 5 as in the modified example 7. . However, the outer electrode layer in the present modification 8 is a layer made of the conductive urethane resin 4a and the insulating melamine resin 4d. Specifically, the conductive urethane resin foam raw material is prepared, poured into a mold and heat-cured and foamed (FIG. 33 (b)), and then the melamine resin is put into the cell (hole) formed by foaming. Coating is performed using a roller coater (FIG. 33C). Thereby, the outer electrode layer in a state where the conductive urethane resin 4a and the insulating melamine resin 4d are randomly dispersed on the insulating layer 5 is formed. The conductive urethane resin portion 4a serves as an outer electrode. In place of melamine resin, urethane, polyimide, polyamide, bakelite, polycarbonate, PET, POM, PPE and the like can also be used. The layer thickness of the outer electrode layer is preferably in the range of 0.01 [mm] to 0.3 [mm]. If it is less than 0.01 [mm], the accuracy of the mold becomes a problem, and if it is greater than 0.3 [mm], an air layer generated by foaming is confined in the outer electrode layer. In this modification 8, the layer thickness of the outer electrode layer was set to 0.1 [mm]. Note that the cell diameter after foaming needs to be equal to or greater than the thickness of the outer electrode layer, as in the case of the insulating particles 4c in the modified example 7.

  Also in this modified example 8, the width of the conductive urethane resin 4a (outer electrode) becomes uneven, and the width of the melamine resin portion 4d (corresponding to the inner electrode facing portion in the modified example 6) also becomes uneven. As a result, similarly to the sixth modification and the seventh modification, it is possible to form a locally strong flare electric field on the toner carrying roller 2 in a distributed manner. Thereby, even when a force for moving the toner in a specific direction is generated due to a potential gradient or an air flow, it is possible to suppress the toner from being unevenly distributed on the toner carrying roller 2. Moreover, as in the case of the modification example 7, it is advantageous over the modification example 6 in that it can cope with forces in other directions such as the direction along the axial direction of the toner carrying roller 2.

[Modification 9]
Next, still another modified example of the outer electrode 4a (hereinafter, this modified example is referred to as “modified example 9”) will be described.
FIG. 34 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 in Modification 9 when cut along a plane orthogonal to the rotation axis.
FIG. 35 is a schematic diagram when the outer electrode layer is viewed from the outer peripheral surface side of the toner carrying roller 2.
Also in the present modification 9, as in the modification 7 and the modification 8, the insulating layer 5 is provided on the outer peripheral surface side of the inner electrode 3a, and then the outer electrode layer is provided on the entire insulating layer 5. However, the outer electrode layer in Modification 9 is a layer in which the metal filler 4a is dispersed in the resin binder 4e. The metal filler 4a is in a fused state with each other. Specifically, a paste material in which a metal filler is dispersed in a resin binder is applied onto the insulating layer 5 by spraying, so that the metal filler 4a is randomly dispersed in the resin binder 4e on the insulating layer 5. An outer electrode layer is formed. In addition, this metal filler part becomes an outer electrode.

  The paste material to be coated on the insulating layer 5 can be used as long as one or more kinds of metal particles such as gold, silver, platinum, palladium, lead, tungsten, and nickel are dispersed as fillers in an organic resin solution. Is possible. Further, as the metal filler 4a, metal oxides such as lead oxide, zinc oxide, silicon oxide, boron oxide, aluminum oxide, yttrium oxide, and titanium oxide may be used. As the binder resin, an epoxy resin, a phenol resin, or the like is preferable. Moreover, isopropyl alcohol etc. are used as a solvent. As a thickener, cellulose or the like may be contained. The amount of the binder resin 4e in the paste material is preferably 40% to 60%. If the amount is too large, the metal filler will not be fused and the electrical resistance will be too high. If the amount is too small, the area occupied by the binder resin 4e will be too small, and the flare electric field formed outside the surface layer 6 will be weak. End up. In this modification 9, it was set to 50%. The layer thickness of the outer electrode layer is preferably in the range of 0.01 [mm] or more and 0.3 [mm] or less, as in the modification 8. In Modification 9, the outer electrode layer thickness was set to 0.1 [mm].

  Also in the present modified example 9, the width of the metal filler 4a (outer electrode) becomes uneven, and the width of the resin binder 4e (corresponding to the inner electrode facing portion in the modified example 6) also becomes uneven. As a result, similarly to the above-described modified examples 6 to 8, locally strong flare electric fields can be dispersedly formed on the toner carrying roller 2. Thereby, even when a force for moving the toner in a specific direction is generated due to a potential gradient or an air flow, it is possible to suppress the toner from being unevenly distributed on the toner carrying roller 2. In addition, as in Modifications 7 and 8, it is more advantageous than Modification 6 in that it can cope with forces in other directions such as the direction along the axial direction of the toner carrying roller 2.

  In Modifications 7 to 9, the same effect can be obtained even when the insulating material portion and the conductive material portion are reversed.

[Modification 10]
Next, a modified example of the inner electrode 3a (hereinafter, this modified example is referred to as “modified example 10”) will be described.
In general, a plurality of types of electrode members (inner electrode 3a and outer electrode 4a) are arranged at different positions in the normal direction of the outer peripheral surface of the toner carrying roller 2, and an insulating layer is interposed between the electrode members as described above. In the configuration, the electrostatic capacity between the electrode members is larger than in the conventional configuration in which a plurality of types of electrodes are provided on the concentric rollers. This is mainly due to the difference in facing area between the electrode members. Since the alternating current supplied to these electrode members increases in proportion to the capacitance, if the capacitance between these electrode members is large, as a power source for supplying power to these electrode members A power supply with a large output current is required. An AC power supply usually increases in cost as the output current increases. Therefore, it is desirable to reduce the capacitance between the electrode members, that is, the capacitance between the inner electrode 3a and the outer electrode 4a as much as possible.

  Here, as a method for reducing the electrostatic capacitance between the inner electrode 3a and the outer electrode 4a, a method of reducing the facing area between the inner electrode 3a and the outer electrode 4a, and the inner electrode 3a and the outer electrode 4a. A method for increasing the distance to the electrode 4a is conceivable. Among these, when the former method is adopted, the structure becomes complicated and the manufacturing cost increases. On the other hand, when the latter method is adopted, a simple structure such as increasing the thickness of the insulating layer 5 interposed between the inner electrode 3a and the outer electrode 4a can be adopted, so that the manufacturing cost does not increase. In this structure, it is difficult to form a strong flare electric field (external electric field) outside the surface layer 6, which eventually increases the power supply cost. The present modification 10 proposes a configuration in which it is easy to form a strong flare electric field outside the surface layer 6 while reducing the capacitance between the inner electrode 3a and the outer electrode 4a with a simple structure.

FIG. 36 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 in Modification 10 when cut along a plane orthogonal to the rotation axis.
The basic structure of the toner carrying roller 2 of the present modification 10 is a four-layer structure as in the above-described embodiment shown in FIG. 4, but in this modification 10, the inner electrode 3a as the innermost peripheral electrode member is formed. The configuration is different. Specifically, as shown in FIG. 36, at least a part of the inner electrode 3a in the moving direction of the toner carrying roller surface, as shown in FIG. 36, the electrode surface of the inner electrode 3a facing the inter-electrode portion of the outer electrode 4a as the outermost peripheral electrode member ( The outer peripheral surface) is positioned closer to the outer peripheral surface of the toner carrying roller than the electrode surface of the inner electrode 3a facing the outer electrode 4a. Thereby, about the distance of the outer electrode 4a and the electrode part of the inner side electrode 3a facing this, the distance B in this modification 10 can be made longer than the distance B 'in the said embodiment. As a result, according to the tenth modification, the capacitance between the inner electrode 3a and the outer electrode 4a can be made smaller than that of the above embodiment.

  On the other hand, the electrode part of the inner electrode 3a facing the inter-electrode part of the outer electrode 4a remains the same as in the above embodiment. In other words, the thickness A of the insulating layer between the interelectrode portion of the outer electrode 4a and the electrode portion of the inner electrode 3a opposite thereto is the same. The flare electric field formed outside the surface layer 6 is mainly formed by the electrode portion of the inner electrode 3a facing the inter-electrode portion of the outer electrode 4a and the outer electrode 4a. In the present modification 10, the positional relationship between the electrode portion of the inner electrode 3a facing the inter-electrode portion of the outer electrode 4a and the outer electrode 4a remains the same as that of the above embodiment. An electric field for flare as strong as that of the above-described embodiment can be formed with the same power source as that of the apparatus.

  As a method of forming the inner electrode 3a as shown in FIG. 36, for example, as in the inner electrode of the above-described embodiment, the outer electrode 4a has a smooth outer peripheral surface side and the interelectrode portion of the outer electrode 4a A method is conceivable in which a portion to be opposed is removed by a known method such as photoresist / etching. In this modification, the uneven pitch of the inner electrode 3a is set to 160 [μm], the cutting width is set to 80 [μm], and the cutting depth is set to 80 [μm].

  In the present modification 10, the inner electrode 3a is scraped along the outer electrode 4a extending in the axial direction of the toner carrying roller 2, and the inter-electrode portion of the outer electrode 4a is opposed to the entire length of each outer electrode 4a. Although the distance from the electrode portion of the inner electrode 3a is increased, the present invention is not limited to this. That is, the electrostatic capacitance between the inner electrode 3a and the outer electrode 4a can be made smaller than that of the above embodiment by scraping at least a part of the inner electrode 3a facing the inter-electrode portion of the outer electrode 4a. Therefore, for example, as shown by the symbol C in FIG. 37, the inner electrode 3a may be scraped along the rotation direction of the toner carrying roller 2.

  Here, in the configuration of the present modification 10, the result of an experiment for measuring the capacitance when the distance B between the outer electrode 4a and the electrode portion of the inner electrode 3a facing the outer electrode 4a is changed will be described. In this experiment, the distance B is set to 15 [compared to the toner carrying roller of the embodiment shown in FIG. 4, that is, the comparative example in which the inner electrode 3a is not removed (layer thickness of the insulating layer 5 = 10 [μm]). It was measured how small the electrostatic capacity was in the configuration example 1 scraped to be [μm] and the configuration example 2 scraped so that the distance B was 20 [μm]. As a result, the capacitance of Configuration Example 1 was 80% with respect to the capacitance of Comparative Example, and the capacitance of Configuration Example 2 was 70% with respect to the capacitance of Comparative Example.

[Modification 11]
Next, a description will be given of a modified example (hereinafter referred to as “modified example 11”) relating to a method for forming irregularities formed on the outer peripheral surface of the toner carrying roller 2.
FIG. 38 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 according to Modification 11 when cut along a plane orthogonal to the rotation axis.
In the present modification 11, the height difference between the electrode portion of the outer electrode 4a and the non-electrode portion (interelectrode region) on the outer peripheral surface of the smooth insulating layer 5 is used to make the difference on the outer peripheral surface of the toner carrying roller 2. Form irregularities. Specifically, the outer electrode 4a divided into a plurality of electrodes along the outer peripheral surface of the toner carrying roller 2 is formed on the smooth surface on the outer peripheral side of the insulating layer 5, and the surface layer 6 is substantially uniform on the outer peripheral side. Apply to a proper thickness. As a result, a surface layer 6 is formed on the outer peripheral surface side of the toner carrying roller of the outer electrode 4a, in which the electrode portion of the outer electrode 4a becomes the convex portion 6b and the inter-electrode region of the outer electrode 4a becomes the concave portion 6a.

  In the conventional flare development method, the thickness of the outer electrode 4a is normally set to be very thin, ie, 0.6 [μm] or more and 2 [μm] or less. Even if the thickness is 10 [μm] or more and 40 [μm] or less, the toner carrying roller cannot form the necessary unevenness on different surfaces. Therefore, in the present modification 11, the outer electrode 4a is formed thicker than usual. As a method of forming the outer electrode 4a having such a thickness, for example, screen printing may be mentioned, but other methods may be used as long as an electrode having a desired thickness can be formed. The height of the convex portion 6b (depth of the concave portion 6a) with respect to the concave and convex portion 6a on the outer peripheral surface of the toner carrying roller 2 formed according to the modified example 11 is appropriately set according to the particle size of the toner to be used. . In the present modification 11, it is preferably within a range of 3 [μm] to 30 [μm].

[Modification 12]
Next, another modified example (hereinafter, referred to as “modified example 12”) relating to a method for forming irregularities formed on the outer peripheral surface of the toner carrying roller 2 will be described.
FIG. 39 is a partial cross-sectional view schematically showing a cross section of the toner carrying roller 2 in Modification 12 when cut along a plane perpendicular to the rotation axis.
The inner electrode 3a in the present modified example 12 is an integral electrode having irregularities formed on the outer peripheral surface thereof, and a conductive material such as SUS or aluminum is formed in a cylindrical shape so as to function as a base of the toner carrying roller 2. It is a molded metal roller. In this modified example 12, the surface on the outer peripheral side of the inner electrode 3a is processed to be uneven, and the unevenness on the outer peripheral surface of the toner carrying roller 2 is formed using the difference in height of the unevenness.

  Specifically, after the surface on the outer peripheral side of the inner electrode 3a is processed to be uneven, the insulating layer 5 is coated on the outer peripheral side so as to have a substantially uniform thickness. On this, an outer electrode 4a divided into a plurality of electrodes is formed along the outer peripheral surface of the toner carrying roller 2, and the surface layer 6 is coated on the outer peripheral side so as to have a substantially uniform thickness. Thus, the convex electrode region 3c of the inner electrode 3a becomes the convex portion 6b on the outer peripheral surface of the toner carrying roller, and the concave electrode region 3b of the inner electrode 3a becomes the concave portion 6a on the outer peripheral surface of the toner carrying roller.

  Each electrode of the outer electrode 4a in the modified example 12 is preferably formed in a region facing the convex electrode region 3c of the inner electrode 3a or a region facing the concave electrode region 3b. This is because if the electrode of the outer electrode 4a is formed so as to straddle the convex electrode region 3c and the concave electrode region 3b of the inner electrode 3a, an appropriate flare electric field may not be formed.

  The present modification 12 is an example in which the outer peripheral surface is formed as an integral electrode, but the inner electrode 3a, like the outer electrode 4a, includes a plurality of electrodes along the outer peripheral surface of the toner carrier. It may be divided into electrodes. In this case, each electrode of the outer electrode 4a is disposed so as to face the inter-electrode region of the inner electrode 3a. Then, the insulating layer 5 and the surface layer 6 are formed so that the electrode of the inner electrode 3 a becomes the convex portion 6 b of the toner carrying roller 2 and the inter-electrode region of the inner electrode 3 a becomes the concave portion 6 a of the toner carrying roller 2.

  In the above-described embodiment (including all modifications), an example in which two types of electrodes 3a and 4a are provided on the toner carrying roller 2 has been described, but this is a case where three or more types of electrodes are provided. However, the same effect can be obtained by interposing an insulating layer between the electrodes.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A toner carrying member such as a toner carrying roller 2 having at least two types of electrode members such as an inner electrode 3a and an outer electrode 4a to which different voltages are applied, and the at least two types of electrode members are different from each other. An electric field for hopping the toner by applying a voltage is formed on the outer peripheral surface of the toner carrier, and the toner hopped by rotating the toner carrier is used to carry a latent image such as the photoreceptor 49. In a developing device that develops the latent image by transporting it to a developing area facing the surface of the body and attaching it to the latent image on the latent image carrier, the toner carrier is formed on the toner carrying area on the outer peripheral surface thereof. A regulating blade that uses unevenness distribution and contacts the convex portion 6b on the outer peripheral surface of the toner carrier on the upstream side of the developing region in the rotation direction of the toner carrier. A contact member such as 3 is provided, and among the toners carried on the outer peripheral surface of the toner carrier, the toner on the convex part 6b is prevented from passing, while the toner in the concave part 6a is allowed to pass. .
According to this, the toner carried on the uneven convex portion 6b formed on the outer peripheral surface of the toner carrier is removed by the contact member, and only the toner that has entered the concave portion 6a on the outer peripheral surface of the toner carrier is obtained. It can be conveyed to the development area. Thereby, the toner amount (M / A) per unit area supplied to the development area can be controlled only by the volume of the recess 6a formed on the outer peripheral surface of the toner carrier and the pitch between the recesses. That is, even when the toner layer thickness on the toner carrier is uneven before entering the contact area between the outer peripheral surface of the toner carrier and the contact member, or the toner layer thickness entering the contact area is Even when it fluctuates over time, the amount of toner per unit area supplied to the development region can be controlled by the volume of the recess 6a and the pitch between the recesses. According to the recent processing technique, the unevenness can be formed on the outer peripheral surface of the toner carrier with high accuracy. Therefore, according to the present invention, the amount of toner per unit area supplied to the development region can be stably and highly accurate. The target amount can be controlled.
Moreover, when passing through the contact area between the outer peripheral surface of the toner carrier and the contact member, the pressure applied to the toner entering the recess 6a is different from the smooth outer peripheral surface of the toner carrier as in the conventional developing device. It is smaller than the pressure applied to the toner when the toner is sandwiched and passed between the layer thickness regulating member. Therefore, according to the present aspect A, it is difficult for the toner to progress as compared with the conventional developing device, and the life of the toner can be extended.
In addition, a conventional developing method using a toner carrier having irregularities formed on the outer peripheral surface and a toner adsorbed on the surface of the toner carrier or a magnetic carrier for development (a general one-component developing method or a two-component developing method that is not a flare developing method) When used in the component development method, on the toner carrier after passing through the contact area with the contact member, the area where the toner is attached (concave part) and the area where the toner is not attached (convex part) Are clearly separated. Then, as a result of supplying the toner carried on the toner carrier in such a state to the developing region, image density unevenness corresponding to the unevenness on the outer peripheral surface of the toner carrier occurs. On the other hand, in this aspect A, since the flare development method is used in which the toner hopped on the outer peripheral surface of the toner carrier is used for development, the toner carrier after passing through the contact area with the contact member On the body, the toner that has entered the concave portion hops and moves to the convex portion, and the toner is dispersed. Therefore, image density unevenness according to the unevenness on the outer peripheral surface of the toner carrier is suppressed.
Further, if the depth of the concave portion 6a on the outer peripheral surface of the toner carrier is set to a value close to the particle diameter of the toner, the effect of frictionally charging the toner when passing through the contact area is enhanced and supplied to the development area. The toner charge amount can be increased. Conversely, if the depth of the recess 6a is set sufficiently larger than the particle diameter of the toner, the triboelectric charging effect is reduced, and as a result, the charge amount of the toner supplied to the development area can be reduced. Thus, according to this aspect A, not only the toner amount (M / A) per unit area supplied to the development area but also the charge amount (Q / M) of the toner supplied to the development area It can be controlled by unevenness on the outer peripheral surface of the carrier.

(Aspect B)
In the above aspect A, the unevenness on the outer peripheral surface of the toner carrier is periodically distributed along the rotation direction of the toner carrier.
According to this, rolling processing and winding processing are possible, and the manufacturing cost can be suppressed at a low cost.

(Aspect C)
In the above aspect A or B, the outer peripheral surface of the toner carrier is formed of a material that gives a charge of a normal toner charging polarity to the toner by frictional charging caused by rubbing with the toner. To do.
According to this, since the toner can be charged by friction between the outer peripheral surface of the toner carrier and the toner, the toner on the toner carrier can be appropriately hopped by the flare electric field (hopping electric field). it can.

(Aspect D)
In any one of the above aspects A to C, the height of the convex portion 6b (depth of the concave portion 6a) with respect to the concave portion 6a on the outer peripheral surface of the toner carrier is in the range of 5 [μm] to 50 [μm]. It is characterized by being within.
According to this, since the depth of the concave portion 6a is close to the particle size of toner that is generally used, the effect of frictionally charging the toner when passing through the contact area is enhanced, and the toner is carried by the flare electric field (hopping electric field). The toner on the body can be appropriately hopped.

(Aspect E)
In any one of the above aspects A to D, a toner supply member such as a toner supply roll 18 that supplies toner on the outer peripheral surface to the outer peripheral surface of the toner carrier by rotating with the toner attached to the outer peripheral surface. And rotating the toner supply member so that there is a speed difference between the surface movement speed of the toner supply member and the surface movement speed of the toner carrier at a location where the toner supply member and the toner carrier are opposed to each other. Drive means for driving.
According to this, since the effect of triboelectrically charging the toner at the location where the toner supply member and the toner carrier are opposed to each other is high, the toner on the toner carrier can be appropriately hopped by the flare electric field (hopping electric field).

(Aspect F)
In any one of the above aspects A to E, the contact member has conductivity, and a voltage equivalent to an average value of voltages applied to the at least two types of electrode members in the toner carrier. It has a voltage application means to apply to the contact member.
Since the surface potential of the toner carrier affects the developing ability in the development region, it is desirable that the surface potential be stable. However, in actuality, the surface of the toner carrier and the contact member are rubbed with each other. The surface potential of the toner carrier fluctuates due to frictional charging due to friction, frictional charging due to friction between the toner to be hopped and the surface of the toner carrier. In the aspect F, the surface potential of the toner carrier can be stabilized by the voltage applied to the contact member.

(Aspect G)
In any one of the above aspects A to F, the at least two types of electrode members in the toner carrier are arranged at different positions in the normal direction of the outer peripheral surface of the toner carrier, and the at least two types The outermost electrode member such as the outer electrode 4a disposed on the outermost peripheral surface side of the toner carrier among the electrode members is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier. An insulating layer 5 is interposed between the electrode members of the outermost electrode, and the plurality of electrodes of the outermost electrode member serve as the convex portions 6b on the outer peripheral surface of the toner carrying member of the outermost electrode member. The surface layer 6 is formed so that the inter-electrode region of the outermost peripheral electrode member becomes the concave portion 6a.
According to this, it is possible to form irregularities on the outer peripheral surface of the toner carrier by a simple method in which each electrode of the outermost peripheral electrode member is formed at a required height and the surface layer is formed substantially uniformly on the outer peripheral side. Can be manufactured.

(Aspect H)
In any one of the above aspects A to F, the at least two types of electrode members in the toner carrier are arranged at different positions in the normal direction of the outer peripheral surface of the toner carrier, and the at least two types Among the electrode members, an inner peripheral electrode member positioned on the inner peripheral side of the toner carrier relative to the other electrode members is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier, and the at least two types Of the electrode members, the outermost peripheral electrode member arranged on the outermost peripheral surface side of the toner carrier is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier, and each electrode is a part of the inner peripheral electrode member. The insulating layer is interposed between the at least two types of electrode members, and a surface layer is formed on the outer peripheral surface side of the toner carrying member of the outermost electrode member. The On the outer peripheral surface side of the inner peripheral electrode member, the plurality of electrodes of the inner peripheral electrode member become the convex portions, and the inter-electrode region of the inner peripheral electrode member is the concave portion. Thus, the insulating layer and the surface layer are formed.
According to this, each electrode of the inner peripheral side electrode member is formed at a required height, and each layer formed on the outer peripheral side thereof is formed in a substantially uniform manner, so that irregularities are formed on the outer peripheral surface of the toner carrier. Can be produced.

(Aspect I)
In any one of the above aspects A to F, the at least two types of electrode members in the toner carrier are arranged at different positions in the normal direction of the outer peripheral surface of the toner carrier, and the at least two types Among the electrode members, the inner peripheral side electrode member located closer to the toner carrying body than the other electrode members is an integral electrode having irregularities formed on the outer peripheral side surface, and the at least two types of electrode members The outermost electrode member disposed on the outermost peripheral surface side of the toner carrier is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier, and an insulating layer is provided between the at least two types of electrode members. And a surface layer is formed on the outer peripheral surface side of the toner carrying member of the outermost electrode member, and the inner peripheral electrode member is disposed on the outer peripheral surface side of the toner carrying member of the inner peripheral electrode member. Convex electrode area 3c is next the convex portion 6b and, as the recess electrode region 3b of the inner peripheral side electrode member is the recess 6a, characterized in that the insulating layer and the surface layer is formed.
According to this, the toner carrier outer peripheral surface can be formed by a simple method in which the convex electrode region 3c in the inner peripheral electrode member is formed at a required height and each layer formed on the outer peripheral side thereof is formed substantially uniformly. The manufacture which can form an unevenness | corrugation on the top can be performed.

(Aspect J)
In the image forming apparatus for developing the latent image by attaching toner to the latent image of the latent image carrier, and finally transferring the resulting toner image to a recording material to form an image, the latent image As a means for developing a latent image on a carrier, a developing device according to any one of the above aspects A to I is used.
According to this, since the amount of toner per unit area supplied to the development area can be stabilized by a method with less stress on the toner, stable image quality can be maintained over a long period of time.

DESCRIPTION OF SYMBOLS 1 Developing device 2 Toner carrying roller 3a Inner electrode 4a Outer electrode 5 Insulating layer 6 Surface layer 6a Concave part 6b Convex part 11 Casing 13 1st accommodating part 15 2nd accommodating part 16 Partition wall 18 Toner supply roller 23 Regulating blade 25A, 25B Pulse power supply 41 Charging Device 42 Exposure Device 43 Primary Transfer Roller 44 Cleaning Device 45 Secondary Transfer Roller 46 Fixing Device 47 Belt Cleaning Device 48 Intermediate Transfer Belt 49 Photoconductor

JP 2009-036929 A

Claims (10)

A toner carrier having at least two types of electrode members to which different voltages are applied, and an electric field for hopping toner by applying different voltages to the at least two types of electrode members The toner formed on the outer peripheral surface of the toner carrier and hopped by rotating the toner carrier is transported to a developing region facing the surface of the latent image carrier to be latent on the latent image carrier. In a developing device for developing the latent image by attaching it to an image,
As the toner carrying member, a toner carrying region having unevenness distributed in the toner carrying region on the outer peripheral surface thereof,
An abutting member is provided on the upstream side of the developing region in the rotation direction of the toner carrier to contact the convex portion on the outer circumferential surface of the toner carrier, and the toner on the convex portion of the toner carried on the outer circumferential surface of the toner carrier. A developing device characterized in that the toner in a recess is allowed to pass while the toner is prevented from passing. The developing device according to claim 1.
The unevenness on the outer peripheral surface of the toner carrying member is periodically distributed along the rotation direction of the toner carrying member. The developing device according to claim 1 or 2,
The developing device according to claim 1, wherein the outer peripheral surface of the toner carrying member is formed of a material that gives a charge of a normal toner charging polarity to the toner by frictional charging generated by rubbing with the toner. The developing device according to any one of claims 1 to 3,
The height of the convex portion with respect to the concave portion on the outer peripheral surface of the toner carrier is in the range of 5 [μm] to 50 [μm]. The developing device according to any one of claims 1 to 4,
A toner supply member for supplying the toner on the outer peripheral surface to the outer peripheral surface of the toner carrier by rotating with the toner attached to the outer peripheral surface;
The toner supply member is rotationally driven so that a speed difference is generated between the surface movement speed of the toner supply member and the surface movement speed of the toner carrier at a position where the toner supply member and the toner carrier are opposed to each other. And a developing unit. The developing device according to any one of claims 1 to 5,
The contact member has electrical conductivity,
A developing device comprising voltage applying means for applying a voltage equivalent to an average value of voltages applied to the at least two kinds of electrode members in the toner carrier to the contact member. The developing device according to any one of claims 1 to 6,
The at least two types of electrode members in the toner carrier are disposed at different positions in the normal direction of the outer peripheral surface of the toner carrier,
Of the at least two types of electrode members, the outermost peripheral electrode member disposed closest to the outer peripheral surface of the toner carrier is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier,
An insulating layer is interposed between the at least two types of electrode members,
On the outer peripheral surface side of the outermost electrode member of the outermost electrode member, the plurality of electrodes of the outermost electrode member are the convex portions, and the inter-electrode region of the outermost electrode member is the concave portion. A developing device having a surface layer formed thereon. The developing device according to any one of claims 1 to 6,
The at least two types of electrode members in the toner carrier are disposed at different positions in the normal direction of the outer peripheral surface of the toner carrier,
Of the at least two types of electrode members, the inner peripheral electrode member positioned closer to the toner carrier inner circumferential side than the other electrode members is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier.
Of the at least two types of electrode members, the outermost peripheral electrode member disposed closest to the outer peripheral surface of the toner carrier is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier, and It is arranged so as to face the inter-electrode region of the peripheral electrode member,
An insulating layer is interposed between the at least two types of electrode members, and a surface layer is formed on the outer peripheral surface side of the outermost peripheral electrode member,
The plurality of electrodes of the inner peripheral electrode member serve as the convex portions and the inter-electrode region of the inner peripheral electrode member serves as the concave portion on the outer peripheral surface side of the toner carrying member of the inner peripheral electrode member. As described above, the developing device is characterized in that the insulating layer and the surface layer are formed. The developing device according to any one of claims 1 to 6,
The at least two types of electrode members in the toner carrier are disposed at different positions in the normal direction of the outer peripheral surface of the toner carrier,
Of the at least two types of electrode members, the inner peripheral electrode member located closer to the toner carrying body than the other electrode member is an integral electrode having irregularities formed on the outer peripheral surface thereof.
Of the at least two types of electrode members, the outermost peripheral electrode member disposed closest to the outer peripheral surface of the toner carrier is divided into a plurality of electrodes along the outer peripheral surface of the toner carrier,
An insulating layer is interposed between the at least two types of electrode members, and a surface layer is formed on the outer peripheral surface side of the outermost peripheral electrode member,
On the outer peripheral surface side of the inner peripheral electrode member, the convex electrode region of the inner peripheral electrode member becomes the convex portion, and the concave electrode region of the inner peripheral electrode member becomes the concave portion. As described above, the developing device is characterized in that the insulating layer and the surface layer are formed. In the image forming apparatus for developing the latent image by attaching toner to the latent image on the latent image carrier, and finally transferring the resulting toner image to a recording material to form an image.
An image forming apparatus using the developing device according to claim 1 as means for developing a latent image on the latent image carrier.

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