WO2015163000A1

WO2015163000A1 - Developing device and image-forming device

Info

Publication number: WO2015163000A1
Application number: PCT/JP2015/055776
Authority: WO
Inventors: 清水　保; 侑佐々木; 栄齋藤; 渡辺　征正
Original assignee: 京セラドキュメントソリューションズ株式会社
Priority date: 2014-04-21
Filing date: 2015-02-27
Publication date: 2015-10-29
Also published as: JP2017106943A

Abstract

　In the present invention there is used a developing device that is characterized by being provided with a toner-supporting body, a bias-applying unit for applying developing bias to the toner-supporting body, a leak-generating unit for generating a leak between the development-supporting body and the toner-supporting body, a leak-detecting unit for detecting the leak, and a bias-controlling unit for configuring the developing bias on the basis of a leak-generated voltage when the leak-detecting unit detects the leak; the toner-supporting body (231) being provided with a base material (35) and a resin layer (36) formed on the base material (35), and the resin layer (36) not peeling from the base material (35) in an adhesive test using cross-cutting.

Description

Developing device and image forming apparatus

The present invention relates to a developing device and an image forming apparatus including the developing device.

A developing device provided in an image forming apparatus using an electrophotographic method, such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these, supplies toner to the surface of an image carrier on which an electrostatic latent image is formed. Thus, there are various developing system developing devices that develop the electrostatic latent image as a toner image.

As such a developing device, for example, a so-called touch-down developing type developing device is preferably used because it can form a high-quality image. The touchdown development type developing device uses a two-component developer containing toner and a carrier as a developer, a developer carrier that carries the two-component developer in the form of a magnetic brush, and an image carrier. And a toner carrying member arranged to face each of the body and the developer carrying member and carrying and transporting the toner of the two-component developer. In this touch-down development type developing device, a two-component developer is first carried on the surface of a developer carrying member and conveyed, and the conveyed two-component developer is brought into contact with a toner carrying member. Next, the developing device causes the toner in the two-component developer to move onto the surface of the toner carrier by the contact, and the transferred toner is carried on the toner carrier to be near the image carrier. Transport to. The developing device develops the toner transported to the vicinity of the image carrier by flying toward the surface of the image carrier.

Further, as the developing device, the toner carried on the surface of the toner carrying member is carried to the vicinity of the image carrying member on which the electrostatic latent image is formed, and the conveyed toner is caused to fly toward the surface of the image carrying member. There is something. The developing device of the touch-down developing system is also an example of a developing device that causes such toner to fly. In such a developing device for flying toner, the toner carrier and the image carrier are separated from each other. In this developing device, when the toner conveyed by the toner carrier is caused to fly to the image carrier, a developing bias is applied to the toner carrier to generate a potential difference between the toner carrier and the image carrier. For this reason, in such a developing device, if the potential difference is made too small, the flying of the toner becomes insufficient. For example, when a halftone image is printed, there is a tendency that shading occurs in the formed image according to the rotation cycle of the toner carrier. On the other hand, if this potential difference is made too large, a so-called discharge (leak) phenomenon occurs in which a leak current flows between the toner carrier and the image carrier that are separated from each other, and a leak mark is generated in the formed image. The image tends to be distorted.

In order to solve such problems, developing devices that perform leak detection are known. As a developing device that performs leak detection, for example, a method of generating a leak in the development region in advance and setting the development bias to a value that is a fixed value lower than the voltage applied to the toner carrier when the leak is detected. Development devices and the like have been proposed.

Further, as the toner carrier provided in the developing device, for example, a developing roller in which a resin layer is coated on a base material may be used for the purpose of reducing toner adhesion. As such a developing roller, the developing roller of patent document 1 is mentioned, for example.

In Patent Document 1, an elastic layer having conductivity is formed on the outer periphery of a highly conductive shaft, and the elastic layer is made of a urethane elastomer containing carbon black having a pH of 5 or more. Describes a developing roller obtained using modified diphenylmethane-4,4′-diisocyanate or crude diphenylmethane-4,4′-diisocyanate.

According to Patent Document 1, it is possible to obtain a high-quality image having low hardness and good adhesion without causing inconveniences that contaminate the photoreceptor and the like, and having no density unevenness or ground fog. It is disclosed that image quality does not deteriorate even when used for a long time.

Japanese Patent Laid-Open No. 10-213965

An object of the present invention is to provide a developing device capable of forming a high-quality image over a long period of time.

A developing device according to an aspect of the present invention includes a toner carrier that is disposed in a noncontact manner on an image carrier on which an electrostatic latent image is formed and supplies toner carried on the surface to the image carrier. A bias applying unit that applies a developing bias to the toner carrier and supplies the toner carried on the surface of the toner carrier to the image carrier; and a leak generation voltage is applied to the toner carrier. In addition, a leak generation unit that generates a leak between the image carrier and the toner carrier, a leak detection unit that detects a leak generated by the leak generation unit, and a leak detection unit that detects the leak A bias control unit for setting the developing bias based on a leakage occurrence voltage at the time, and the toner carrier includes a base material and a resin layer formed on the base material, In the adhesion test, the resin layer is cut to the base material in the thickness direction so that the resin layer is divided into a 5 mm-interval grid, and the adhesive tape is adhered to the grid-cut resin layer. The cut resin layer does not peel from the substrate when it is peeled off.

According to another aspect of the present invention, there is provided a developing device that supplies toner, which is disposed on a surface of an image carrier on which an electrostatic latent image is formed in a non-contact manner and is carried on the surface, to the image carrier. A toner carrier, a developer carrier for supplying toner contained in the two-component developer to the toner carrier from a two-component developer containing toner and carrier carried on the surface, and the toner A first developing bias is applied to the carrier to supply the toner carried on the surface of the toner carrier to the image carrier, and a second developing bias is applied to the developer carrier. And a second bias applying unit that supplies the toner carrier with toner contained in the two-component developer carried on the surface of the developer carrier, and the toner carrier comprises: A resin layer formed on the substrate; In the adhesion test by the cross-cut method, the resin layer is cut to the base material in the thickness direction so that the resin layer is divided into a grid shape with an interval of 5 mm. When the adhesive tape is peeled off after being adhered, the cut resin layer is not peeled off from the substrate.

According to the present invention, it is possible to provide a developing device capable of forming a high-quality image over a long period of time.

FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus including a developing device according to an embodiment of the present invention. FIG. 2 is a schematic sectional view showing the developing device according to the embodiment of the present invention. FIG. 3 is a perspective view showing an example of a developing roller provided in the developing device according to the embodiment of the present invention. 4 is a cross-sectional view of the developing roller shown in FIG. FIG. 5 is a perspective view showing another example of the developing roller provided in the developing device according to the embodiment of the present invention. 6 is a cross-sectional view of the developing roller shown in FIG.

According to the study by the present inventors, a developing roller in which a resin layer made of polyurethane containing carbon black as described in Patent Document 1 is formed as a toner carrier on a substrate, as described above. When the image forming apparatus is provided in a developing device that performs detection or a touch-down developing system, the resin layer formed on the substrate may be peeled off when an image is formed over a long period of time. In such a case, suitable image formation cannot be maintained over a long period of time.

The inventors of the present invention have focused on the following as the cause of the resin layer formed on the base material of the toner carrier peeling off when image formation is performed over a long period of time.

First, since a developing device that performs leak detection intentionally generates a leak, a strong voltage that causes a leak is applied to the toner carrier at that time. In addition, the developing device of the touch-down development system applies a strong voltage that causes a relatively large potential difference between the toner carrier and the developer carrier in order to form a uniform toner layer on the toner carrier. Apply to toner carrier. As described above, any developing device applies a relatively strong voltage to the toner carrier. For this reason, the present inventors paid attention to the fact that the resin layer is easily peeled off in a developing device that applies a relatively strong voltage to the toner carrier.

The inventors have found that when a relatively strong voltage is applied to the toner carrier, a large amount of current flows through the magnetic brush or a leak occurs between the image carrier and the toner carrier. Thus, it was considered that pinholes were formed in the resin layer of the toner carrier. And the present inventors considered that the peripheral resin layer in which the pinhole was formed was slightly separated from the base material. The slight float of the resin layer was not a problem as long as the image was formed in a relatively short time. For this reason, even in order to suitably perform image formation over a long period of time, it has not been conventionally considered to pay attention to the separation between the base material and the resin layer. However, as a result of detailed studies by the present inventors, it has been found that when an image is formed over a long period of time, the resin layer is peeled off. The present inventors considered that this peeling occurs when a plurality of floats are connected to each other.

Therefore, as a result of intensive investigations focusing on the adhesion between the resin layer and the base material in the toner carrier, the present inventors have found that the above object can be achieved by the present invention as follows.

Hereinafter, embodiments according to the present invention will be described, but the present invention is not limited thereto.

Here, as an image forming apparatus including the developing device according to the embodiment of the present invention, a tandem image forming apparatus will be described as an example. However, any image forming apparatus using an electrophotographic method may be used. It is not limited to the image forming apparatus. The type of image forming apparatus will be described by taking a color printer as an example. However, for example, it may be a copying machine, a facsimile machine, a multifunction machine, or the like, and is not limited to a color printer.

An image forming apparatus 10 including a developing device according to an embodiment of the present invention performs image forming processing based on image information transmitted from an external device such as a computer, and is a so-called tandem image forming apparatus (color A printer 10 will be described as an example. FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus including a developing device according to an embodiment of the present invention.

As shown in FIG. 1, the image forming apparatus 10 includes a paper feeding unit 12 that feeds paper P and is fed from the paper feeding unit 12. An image forming unit 13 that forms a toner image based on image information on the paper P, and a fixing unit 14 that performs a fixing process for fixing an unfixed toner image formed on the paper P by the image forming unit 13 to the paper P. Is provided. Further, on the upper part of the apparatus main body 11, a paper discharge unit 15 for discharging the paper P subjected to the fixing process by the fixing unit 14 is formed.

An unillustrated operation panel is provided at an appropriate position on the upper surface of the apparatus main body 11 to input an output condition for the paper P. The operation panel is provided with a power key and various keys for inputting output conditions.

In the apparatus main body 11, the paper P is transported from the paper feed unit 12 to the paper discharge unit 15, and the paper P being transported passes through the transfer unit and the fixing unit 14 of the image forming unit 13. A conveyance path 111 is formed. In the paper transport path 111, a transport roller pair 112 for transporting the paper P is provided at an appropriate place.

The paper feed unit 12 includes a paper feed tray 121, a pickup roller 122, and a paper feed roller pair 123. The paper feed tray 121 is detachably mounted at the entrance of the paper transport path 111, in FIG. 1, at a position below the image forming unit 13 in the apparatus main body 11. Store. The pickup roller 122 is provided at an upper position on the upstream side of the paper feed tray 121 in the conveyance direction of the paper P, specifically, at an upper left position shown in FIG. The top sheet P is taken out one by one. The paper feed roller pair 123 sends the paper P taken out by the pickup roller 122 to the paper transport path 111. Through these operations, the paper feeding unit 12 feeds the paper P toward the image forming unit 13.

The paper feeder 12 further includes a manual feed tray 124, a pickup roller 125, and a paper feed roller pair 126 that are attached to the right side surface of the apparatus main body 11 shown in FIG. The manual feed tray 124 is for supplying the paper P toward the image forming unit 13 by manual feed operation. The manual feed tray 124 can be stored on the side surface of the apparatus main body 11, and when the paper P is manually fed, as shown in FIG. 1, the manual feed tray 124 is pulled out from the side surface of the apparatus main body 11 to be manually fed. The pickup roller 125 takes out the paper P placed on the manual feed tray 124. The paper P taken out by the pickup roller 125 is sent out to the paper transport path 111 by the paper feed roller pair 126. Through these operations, the paper feeding unit 12 feeds the paper P toward the image forming unit 13.

The image forming unit 13 forms an image such as a color image on the paper P fed from the paper feeding unit 12 by predetermined image processing. The image forming unit 13 includes a plurality of image forming units 131, an intermediate transfer belt (intermediate transfer member) 132, a primary transfer roller 133, and a secondary transfer roller 134.

In the present embodiment, the image forming unit 131 is magenta (M) that is sequentially disposed from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 132 (from the right side to the left side in FIG. 1). Magenta unit 131M using a color developer, cyan unit 131C using a cyan (C) developer, yellow unit 131Y using a yellow (Y) developer, and black (K) developer A black unit 131K using the above is provided. Each unit 131 includes a photosensitive drum 135 as an image carrier, and forms a toner image corresponding to each color on the photosensitive drum 135 based on image information, and performs primary transfer onto the intermediate transfer belt 132.

Further, in the image forming unit 131, a photosensitive drum 135 as an image carrier is disposed at a central position so as to be rotatable in the direction of an arrow (indicated by an arrow A in FIG. 2). In addition, when the position (primary transfer) transferred by the primary transfer roller 133 is set to the most upstream side in the rotation direction of the photosensitive drum 135 around the photosensitive drum 135, the position moves from there to the downstream side. In this order, a cleaning device 24, a charging device 21, an exposure device 22, and a developing device 23 are arranged.

The photosensitive drum (image carrier) 135 forms a toner image corresponding to each color based on image information on the peripheral surface thereof by a charging process, an exposure process, a development process, and a charge removal process, which will be described later. Is for. The photoconductor drum 135 is not particularly limited as long as it is a photoconductor drum that can be provided in the image forming apparatus, and examples thereof include an organic photoconductor (OPC) drum and an amorphous silicon (a-Si) photoconductor drum. It is done.

The charging device 21 charges the peripheral surface of the photosensitive drum 135 rotated in the direction of the arrow. The charging device 21 is not particularly limited as long as it is a charging device that can be provided in the image forming apparatus. Specifically, for example, a charging device including a charging roller and applying a predetermined charging bias to the charging roller to charge the peripheral surface of the photosensitive drum, or a non-contact discharge corotron type And a scorotron type charging device.

The exposure device 22 irradiates the peripheral surface of the photosensitive drum 135 whose peripheral surface is charged by the charging device 21 with laser light or LED light based on image information, and converts the image information onto the peripheral surface of the photosensitive drum 135. For forming an electrostatic latent image based thereon. The exposure device 22 is not particularly limited as long as it is an exposure device provided in the image forming apparatus. Specifically, an LED head unit, a laser scanning unit (LSU), etc. are mentioned, for example.

The developing device 23 is for developing the electrostatic latent image formed on the peripheral surface of the photosensitive drum 135 into a toner image. The configuration of the developing device 23 will be described later.

The cleaning device 24 transfers (primary transfer) the toner image on the circumferential surface of the photosensitive drum 135 to the intermediate transfer belt 132 by the primary transfer roller 133, and then remains on the circumferential surface of the photosensitive drum 135. This is for removing the toner. The peripheral surface of the photosensitive drum 135 from which the toner remaining after the primary transfer is removed by the cleaning device 24 is directed to a charging position by the charging device 21 for a new image forming process. The waste toner removed by the cleaning device 24 is collected and stored in a toner collection bottle (not shown) through a predetermined path.

Further, before the toner is removed by the cleaning device 24, the peripheral surface of the photosensitive drum 135 may be neutralized by a neutralization device (not shown). By doing so, the toner remaining on the peripheral surface of the photosensitive drum 135 after the primary transfer is suitably removed by the cleaning device 24.

The intermediate transfer belt 132 is for transferring (primary transfer) a toner image based on image information to the peripheral surface (contact surface) of the plurality of image forming units 131. That is, in this embodiment, the intermediate transfer belt 132 is a transfer target that is sandwiched between the photosensitive drum 135 and the primary transfer roller 133 and has a peripheral surface to which a toner image is transferred from the photosensitive drum 135. .

Further, the intermediate transfer belt 132 is an endless belt-like rotating body, and the driving roller 136, the belt support roller 137, and the tension roller 139 so that the circumferential surface side thereof is in contact with the circumferential surface of each photoconductor 135. It is stretched over. Further, the intermediate transfer belt 132 is pressed against each photoconductor drum 135 by each primary transfer roller 133 disposed at a position facing each photoconductor drum 135 via the intermediate transfer belt 132, and the driving roller 136. It is comprised so that it may rotate endlessly by rotational drive. The driving roller 136 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 132 endlessly. The belt support roller 137 and the tension roller 139 are driven rollers that are rotatably provided and rotate following the endless rotation of the intermediate transfer belt 132 by the driving roller 136. These driven

rollers

137 and 139 are driven to rotate via the intermediate transfer belt 132 according to the main rotation of the driving roller 136 and support the intermediate transfer belt 132. Further, the tension roller 139 applies tension (tension) to the intermediate transfer belt so that the intermediate transfer belt 132 does not loosen. The tension roller 139 is biased by a biasing member such as a spring body, for example, so that the intermediate transfer belt 132 is moved from the back surface (inner peripheral side) to the front surface (outer peripheral side). The tension is generated by applying a pressing force to the belt 132.

The primary transfer roller 133 is for primary transfer of the toner image formed on the photosensitive drum 135 to the intermediate transfer belt 132. That is, in this embodiment, the primary transfer roller 133 holds the intermediate transfer belt 132 between the photosensitive drum 135 and the toner image on the circumferential surface of the photosensitive drum 135 to the intermediate transfer belt 132 for primary transfer. It is a transfer part to be made.

The primary transfer roller 133 is disposed at a position facing each photoconductor drum 135 with the intermediate transfer belt 132 interposed therebetween. The primary transfer roller 133 is provided for each photosensitive drum 135. In addition, the primary transfer roller 133 rotates depending on the endless rotation of the intermediate transfer belt 132 while being in contact with the intermediate transfer belt 132. At that time, by applying a primary transfer bias having a polarity opposite to the charging polarity of the toner to each primary transfer roller 133, a toner image formed on each photoconductor drum 135 becomes a photoconductor drum 135. And the corresponding primary transfer rollers 133 are primarily transferred to the intermediate transfer belt 132. As a result, the toner images formed on the respective photosensitive drums 135 are sequentially primary-transferred sequentially in an overcoated state on the intermediate transfer belt 132 that rotates in the direction of an arrow (clockwise in FIG. 1).

The secondary transfer roller 134 is for transferring (secondary transfer) the toner image on the intermediate transfer belt 132 onto the paper P fed from the paper feeding unit 12. That is, in the present embodiment, the secondary transfer roller 134 contacts the peripheral surface of the intermediate transfer belt 132 to form a nip portion, and the intermediate transfer belt 132 is formed on a sheet P that is a recording medium passing through the nip portion. 2 is a secondary transfer portion for secondary transfer of the toner image on the peripheral surface of the toner.

The secondary transfer roller 134 is disposed at a position facing the driving roller 136 with the intermediate transfer belt 132 interposed therebetween. Further, the secondary transfer roller 134 is rotated in accordance with the endless rotation of the intermediate transfer belt 132 while being in contact with the intermediate transfer belt 132. At that time, the toner on the circumferential surface of the intermediate transfer belt 132 is secondarily transferred between the secondary transfer roller 134 and the driving roller 136 onto the paper P fed from the paper feeding unit 12. As a result, the toner image based on the image information is transferred onto the paper P in an unfixed state.

The image forming unit 13 further includes a belt cleaning device 138 on the intermediate transfer belt 132 at a position downstream of the secondary transfer position in the rotational direction and upstream of the primary transfer position. The belt cleaning device 138 is for cleaning the intermediate transfer belt 132 by removing the toner remaining on the peripheral surface of the intermediate transfer belt 132 after the secondary transfer. The peripheral surface of the intermediate transfer belt 132 cleaned by the belt cleaning device 138 goes to the primary transfer position for a new primary transfer process. The waste toner removed by the belt cleaning device 138 is collected and stored in a toner collection bottle (not shown) through a predetermined path.

The fixing unit 14 performs a fixing process on the toner image on the paper P that has been secondarily transferred by the secondary transfer roller 134. The fixing unit 14 is stretched between a heating roller 141 including an energization heating element serving as a heating source therein, a fixing roller 142 disposed opposite to the heating roller 141, and the fixing roller 142 and the heating roller 141. A fixing belt 143 and a pressure roller 144 disposed to face the fixing roller 142 with the fixing belt 143 interposed therebetween are provided.

The paper P supplied to the fixing unit 14 is heated and pressurized by passing through a fixing nip formed between the fixing belt 143 and the pressure roller 144. As a result, the toner image secondarily transferred to the paper P by the secondary transfer roller 134 is fixed to the paper P. The sheet P that has been subjected to the fixing process is discharged toward the sheet discharge tray 151 of the sheet discharge unit 15 provided at the top of the apparatus main body 11 through the sheet conveyance path 111 extending from the upper part of the fixing unit 14. Paper.

The paper discharge unit 15 is formed by recessing the top of the apparatus main body 11, and a paper discharge tray 151 for receiving the discharged paper P is formed at the bottom of the concave portion.

Next, the developing device according to the embodiment of the present invention will be described.

The developing device according to the embodiment of the present invention is a developing device that performs leak detection or a touch-down developing type developing device, which will be described later.

Specifically, the developing device that performs leak detection is a toner that is disposed in a non-contact manner and opposed to an image carrier on which an electrostatic latent image is formed, and supplies toner carried on the surface to the image carrier. A carrier, a bias applying unit for applying a developing bias to the toner carrier and supplying the toner carried on the surface of the toner carrier to the image carrier, and a leakage generating voltage on the toner carrier. To generate a leak between the image carrier and the toner carrier, a leak detector for detecting a leak generated by the leak generator, and a leak detector by the leak detector And a bias control unit that sets the developing bias based on a leak occurrence voltage at the time of detection. With such a developing device, it is possible to set a developing bias by detecting a leak, and thus it is possible to realize suitable image formation.

Further, the touch-down developing type developing device, specifically, the toner contained in the two-component developer from the toner carrier and the two-component developer carried on the surface including the toner and the carrier. A developer carrier to be supplied to the toner carrier, and a first developing bias applied to the toner carrier to supply the toner carried on the surface of the toner carrier to the image carrier. A second applying bias is applied to the bias applying unit and the developer carrying member to supply the toner contained in the two-component developer carried on the surface of the developer carrying member to the toner carrying member. A bias applying unit. Since such a developing device is a so-called touch-down developing type developing device, suitable image formation can be realized.

The toner carrier provided in each of the developing devices according to the embodiment of the present invention includes a base material and a resin layer formed on the base material. Then, in the adhesion test by the cross-cut method, the toner carrier is cut into the base material in the thickness direction so that the resin layer is divided into a grid shape with an interval of 5 mm. When the adhesive tape is brought into close contact with the cut resin layer and then peeled off, the cut resin layer does not peel from the substrate. That is, the toner carrier has an adhesive property that prevents the resin layer from being peeled off from the substrate in the adhesion test by the cross-cut method as described above.

Since such a toner carrier has a sufficiently high adhesion of the resin layer, it can be provided in a developing device that performs leak detection as described above, or in a developing device of the touch-down developing method as described above. Even when used for long-term image formation, peeling of the resin layer can be sufficiently suppressed. Therefore, each of the developing devices according to the present embodiment is a developing device that performs leak detection as described above or a developing device of the touch-down developing method as described above. A high-quality image can be formed.

In the developing device of the touch-down development method, the AC electric field strength between the toner carrier and the developer carrier is a ratio of the distance between the toner carrier and the developer carrier [( The amplitude of the difference between the second developing bias and the first developing bias: AC bias between MS / (distance between toner carrier and developer carrier: distance between MS)] is 6000 to 12500 V / mm It is preferable. Specifically, the ratio of the AC voltage between the second development bias and the first development bias to the distance between MSs (AC bias between MSs / MS distance) is preferably 6000 to 12500 V / mm, It is more preferably 7000 to 11500 V / mm, and further preferably 8000 to 10500 V / mm. A more uniform toner layer can be formed on the toner carrier by making the potential difference between the toner carrier and the developer carrier the same as the above electric field strength. Image formation can be realized. On the other hand, when a relatively high voltage that causes such a relatively large potential difference is applied to the toner carrier, the resin layer tends to peel off. By using it, since the adhesiveness of the resin layer is sufficiently high, peeling of the resin layer can be sufficiently suppressed. That is, with each of the developing devices according to the present embodiment, since the adhesion of the resin layer in the toner carrier provided is sufficiently high, the peeling of the resin layer can be sufficiently suppressed. For these reasons, it is possible to achieve both the ability to form a higher quality image and the ability to form the higher quality image over a long period of time.

The developing device according to the embodiment of the present invention may be a developing device that performs leak detection or a touch-down developing type developing device as long as it includes the toner carrier as described above. A touch-down developing type developing device that performs detection may be used. Here, a touch-down developing type developing device that performs leak detection will be described as an example. Such a developing device will be described with reference to FIG. FIG. 2 is a schematic sectional view showing the developing device according to the embodiment of the present invention. FIG. 2 also shows the photosensitive drum as well as the developing device.

As described above, the developing device 23 is for developing the electrostatic latent image formed on the circumferential surface of the photosensitive drum 135 into a toner image. As shown in FIG. 2, the developing device 23 includes a developing roller (toner carrier) 231, a magnetic roller (developer carrier) 232, and a stirring and conveying member 237 that are built in the developing container 236. ing. The developing roller 231 is connected to a developing bias applying unit (first bias applying unit) 241, and the magnetic roller 232 is connected to a toner supply bias applying unit (second bias applying unit) 242. In addition, a bias control unit 243 and a leak detection unit 244 are connected to the development bias application unit 241. The leak detection unit 244 is also connected to the bias control unit 243. In addition, a bias control unit 243 is connected to the toner supply bias application unit 242.

The developing container 236 is a developing tank that constitutes the outline of the developing device 23 and contains a two-component developer containing a carrier and toner. The developing container 236 has an opening 236 a that exposes the developing roller 231 toward the photosensitive drum 135. The developing container 236 is formed with a first transport path 236c and a second transport path 236d that are partitioned by a partition portion 236b. Further, the developing container 236 rotatably holds the developing roller 231, the magnetic roller 232, and the stirring and conveying member 237.

The developing roller 231 is opposed to each of the photosensitive drum 135 and the magnetic roller 232 and is spaced apart with the opposed peripheral surfaces in proximity to each other. That is, the developing roller 231 and the photosensitive drum 135 are spaced apart from each other with their peripheral surfaces close to each other, thereby forming a developing region D for supplying toner to the photosensitive drum 135. Further, the developing roller 231 and the magnetic roller 232 are also arranged apart from each other with their peripheral surfaces close to each other.

The magnetic roller 232 conveys to the vicinity of the developing roller 231 by carrying a two-component developer containing toner on the peripheral surface thereof by a magnetic pole member M fixedly disposed inside and rotating in that state. By doing so, the magnetic roller 232 supplies the toner of the two-component developer to the developing roller 231.

Then, the developing roller 231 carries the toner supplied from the magnetic roller 232 on its peripheral surface, and conveys the toner to the vicinity of the photosensitive drum 135 by rotating in this state. By doing so, the electrostatic latent image previously formed on the peripheral surface of the photosensitive drum 135 is visualized (developed) as a toner image.

The stirring and conveying member 237 includes a first stirring and conveying member (stirring mixer) 234 and a second stirring and conveying member (paddle mixer) 233. The first stirring and conveying member 234 is provided in the first conveying path 236c, and the second stirring and conveying member 233 is provided in the second conveying path 236d.

The paddle mixer 233 and the agitation mixer 234 have spiral blades and agitate while conveying the two-component developer in opposite directions to charge the toner contained in the two-component developer. Further, the paddle mixer 233 supplies a two-component developer containing charged toner to the magnetic roller 232.

The ear cutting blade 235 is arranged with its one end facing the peripheral surface of the magnetic roller 232, and regulates the thickness of the two-component developer carried on the magnetic roller 232.

The magnetic roller 232 includes a roller shaft 232a, a magnetic pole member M, and a nonmagnetic sleeve 232b made of a nonmagnetic material. As described above, the magnetic roller 232 carries the developer supplied by the paddle mixer 233 of the stirring and conveying member 237, and supplies toner from the carried developer to the developing roller 231. The magnetic pole member M is a member in which a plurality of magnets having different magnetic poles on the outer peripheral portion formed in a sector shape are alternately arranged and fixed to the roller shaft 232a by adhesion or the like. The roller shaft 232a is supported by the developing container 236 in a non-rotatable manner within the nonmagnetic sleeve 232b with a predetermined gap between the magnetic pole member M and the nonmagnetic sleeve 232b. The nonmagnetic sleeve 232b is rotated in the arrow direction (the same direction as the developing roller 231 and the clockwise direction in FIG. 2) by a driving mechanism including a motor and gears (not shown).

The developing roller 231 includes a fixed shaft 231a, a developing sleeve 231b, and the like. The fixed shaft 231a is supported by the developing container 236 so as not to rotate. The developing sleeve 231b is rotated in the direction of the arrow (in the clockwise direction in FIG. 2) by a driving mechanism including a motor and gears (not shown).

The toner supply bias application unit (second bias application unit) 242 applies a toner supply bias (second bias) to the roller shaft 232a of the magnetic roller 232. By applying the toner supply bias, the magnetic roller 232 carries the toner of the two-component developer carried on the surface thereof and transported to the vicinity of the developing roller 231 to the developing roller 231.

The development bias application unit (first bias application unit) 241 is for applying the development bias (first bias) to the fixed shaft 231a of the development roller 231. By applying a developing bias, the developing roller 231 carries the toner carried on the surface thereof and transported to the vicinity of the photosensitive drum 135 to the photosensitive drum 135.

Further, the developing bias applying unit 241 and the toner supply bias applying unit 242 include an AC power source that applies an AC voltage. In other words, the development bias applied by the development bias application unit 241 and the toner supply bias applied by the toner supply bias application unit 242 include an AC component. Further, the development bias applying unit 241 and the toner supply bias applying unit 242 may further include a DC power source for applying a DC voltage, as shown in FIG. That is, the development bias applied by the development bias application unit 241 and the toner supply bias applied by the toner supply bias application unit 242 may be a superimposed voltage in which an AC component is superimposed on a DC component.

Further, the developing bias applying unit 241 and the toner supply bias applying unit 242 include a bias control unit 243 that controls a DC voltage, an AC voltage, and the like of the developing bias and the toner supply bias applied thereby.

Also, the leak detection unit 244 is connected to the development bias application unit 241 and the bias control unit 243. In addition to the developing operation, the leak detector 244 changes the developing bias to generate a leak between the photosensitive drum 135 and the developing roller 231 and detects a leak generating voltage at which the leak occurs. Specifically, the leak detection unit 244 generates a leak between the photosensitive drum 135 and the developing roller 231 while increasing the peak-to-peak voltage of the AC voltage of the developing bias, and between the peaks where the leak occurs. The voltage is detected as a leak generation voltage. The bias control unit 243 then develops the development bias based on the leak occurrence voltage detected by the leak detection unit 244 so that no leak occurs during the development operation, that is, within a range where the development bias does not reach the leak occurrence voltage. To control.

From the above, the developing device according to the present embodiment intentionally generates a leak during the leak detection operation, and at that time, a strong voltage that causes a leak is applied to the developing roller. In addition, it is desired that a developing device of the touch-down development system applies a strong voltage to the developing roller in order to form a uniform toner layer on the developing roller. The developing device according to the present embodiment sets the development bias based on the leak occurrence voltage detected by the leak detection operation so that no leak occurs during the development operation, that is, within a range where the development bias does not reach the leak occurrence voltage. Control. For these reasons, since the developing device according to the present embodiment employs the touch-down developing method, the developing bias applied to the developing roller is relatively high within the range where the developing bias is less than the leakage occurrence voltage. . In such a developing device, when a developing roller having a resin layer formed on a substrate is used, as described above, the resin layer is easily peeled off. Therefore, in the developing device according to the present embodiment, a developing roller described later is used as a developing roller that is a toner carrier.

Next, the developing roller (toner carrier) provided in the developing device according to the embodiment of the present invention will be described.

As described above, the toner carrier is a developing roller including a base material and a resin layer formed on the base material. This developing roller was cut into a lattice shape by cutting the resin layer to the base material in the thickness direction so that the resin layer was divided into a lattice shape with an interval of 5 mm in an adhesion test by a cross-cut method. When the adhesive tape is adhered to the resin layer and then peeled, the developing roller has adhesiveness that prevents the cut resin layer from peeling from the substrate. Examples of the developing roller include the following developing rollers.

First, the developing roller shown in FIGS. 3 and 4 will be described.

FIG. 3 is a perspective view showing an example of a developing roller provided in the developing device according to the embodiment of the present invention. FIG. 3 shows the developing roller with a part thereof cut. 4 is a cross-sectional view of the developing roller shown in FIG.

As shown in FIGS. 3 and 4, the developing roller 231 includes a cylindrical rotating sleeve 32 and a fixed shaft 33 included in the rotating sleeve 32, and the position of the fixed shaft 33 is fixed. The rotating sleeve 32 rotates around the periphery.

As shown in FIGS. 3 and 4, the rotating sleeve 32 has a resin layer 36 coated on a base material 35. Examples of the substrate 35 include a cylindrical member made of aluminum, stainless steel, or the like. Examples of the fixed shaft 33 include a shaft 37 that is pivotally supported by the developing device and that is connected by a plurality of ribs 38.

The resin layer 36 is not particularly limited as long as it is a resin layer that does not cause peeling as described above, although it varies depending on the substrate 35. This peel test is a method based on JIS K5600-5-6. Specifically, as the peel test, first, the blade was applied to the resin layer of the obtained developing roller at a right angle, and the substrate was cut at intervals of 5 mm to form five cuts. To do. Thereafter, the direction of 90 ° is changed with respect to the cut formed by the cutting, and similarly, the resin layer is cut to the base material to form five cuts. By doing so, the resin layer is divided into a grid of 5 mm intervals, and a total of 16 grid-like grids are formed. A cross-cut cello tape as defined in JIS K5600-5-6, for example, a cello tape having a width of 24 mm (registered trademark, CT-24 manufactured by Nichiban Co., Ltd.) or the like is attached on the formed grid. Then, this cellophane is peeled off. At that time, the number of lattice-like resin layers peeled off simultaneously with the peeling of the cellophane tape is measured. The developing roller in this embodiment is not peeled off. That is, the number of grid-like resin layers to be peeled is zero.

Since the developing roller does not come into contact with the photosensitive drum as the image carrier, even the developing roller having a resin layer on the surface layer has not been required to have adhesiveness of the resin layer. Specifically, the developing roller has an adhesion to the mechanical force as described above, such that the resin layer does not peel off when the cellophane is applied and peeled off as the adhesion of the resin layer to the substrate. Sex was not required. In the present embodiment, since the adhesiveness is such that the resin layer does not peel even in the above-described test, the resin layer does not peel even in a developing device in which the resin layer peels easily. Therefore, whether it is a developing device that performs leak detection, a touch-down developing type developing device, or a touch-down developing type developing device that performs leak detection, a high-quality image over a long period of time. Can be formed.

The resin layer 36 is not particularly limited as long as it is a resin layer as described above. For example, the resin layer 36 includes an alcohol-soluble polyamide resin and a conductive material dispersed in the polyamide resin, and the conductive material is oxidized. It is preferable that it consists of titanium. If the toner carrier has such a resin layer, the adhesion of the resin layer to the base material is higher, and the peeling of the resin layer can be further suppressed. In addition, since the resin layer includes a conductive material made of titanium oxide, charges accumulated on the surface of the resin layer can be suitably removed from the reason described later. For these reasons, the developing device including this toner carrier can form a more suitable image over a long period of time.

The polyamide resin is not particularly limited as long as it is a polyamide resin capable of realizing the resin layer as described above. Specifically, as described above, the polyamide resin is preferably a polyamide resin that is soluble in alcohol such as methanol. With such a polyamide resin, when the resin layer is formed by a so-called dipping method in which the base material is immersed in a liquid containing the polyamide resin and the conductive material, alcohol is used as a solvent for the liquid. By using, the said polyamide resin melt | dissolves suitably and it becomes the liquid in which the polyamide resin melt | dissolved uniformly as said liquid. A suitable resin layer can be formed by using such a liquid and forming a resin layer by a dipping method. That is, a resin layer having higher adhesion to the substrate can be suitably formed. Therefore, it is possible to obtain a developing device that can further suppress the peeling of the resin layer and can form a more suitable image over a long period of time.

Further, specifically, the polyamide resin preferably has a repeating unit having 8 or less carbon atoms per amide bond. By this, the resin layer with higher adhesiveness with respect to a base material can be formed suitably. Examples of such a polyamide resin include polyamide resins containing any of the repeating units represented by the following formulas (1) to (3). Further, such a polyamide resin may have any one of repeating units represented by the following formulas (1) to (3). For example, an amide bond 1 as represented by the following formula (4) may be used. It may have a repeating unit having more than 8 carbon atoms. Such a polyamide resin may be a block copolymer or a random copolymer in the case of a copolymer having a plurality of repeating units represented by the following formulas (1) to (4).

In addition, the polyamide resin preferably has a number average molecular weight of 1000 to 50000.

In the polyamide resin, the average degree of polymerization a, b, c, d of each repeating unit is not particularly limited as long as the degree of polymerization satisfies the number average molecular weight.

As the polyamide resin, Amilan CM8000 manufactured by Toray Industries, Inc., which is a copolymer having all the repeating units represented by the above formulas (1) to (4), can be preferably used.

The conductive material is preferably made of titanium oxide. This titanium oxide has a higher resistance and a higher dielectric constant than, for example, other conductive materials such as carbon black. For this reason, by using titanium oxide as a conductive material, the obtained toner carrier can suitably remove charges accumulated on the surface thereof. Moreover, the titanium oxide as a electrically conductive material can fully suppress the fall of the fall of the adhesiveness of the resin layer to a base material.

Titanium oxide is not particularly limited, but preferably has an average primary particle size of 10 to 50 nm. If the titanium oxide is too small, reaggregation occurs and dispersion in the resin layer tends to be difficult. On the other hand, if the titanium oxide is too large, it becomes difficult to hold it in the resin layer, and the titanium oxide tends to be easily detached.

In addition, the average primary particle diameter of titanium oxide can be understood from the standard value of the product and the measurement using a general particle size meter. Specifically, for example, it can be measured using a vibration viscometer manufactured by CBC Corporation.

The content of titanium oxide is not particularly limited, but for example, it is preferably 50 to 125 parts by mass with respect to 100 parts by mass of the polyamide resin. When the content of titanium oxide is too small, electric charges are likely to be accumulated in the developing roller, and there is a tendency that a rapid density drop is likely to occur during continuous paper feeding. Moreover, when there is too much content of titanium oxide, there exists a tendency for the binding property of a titanium oxide and resin to become weak, or for a resin layer to peel from a base material easily.

The thickness of the resin layer is preferably 2 to 15 μm, more preferably 2 to 11 μm, and further preferably 2 to 9 μm.

The base material is preferably an aluminum base material, more preferably a surface of the aluminum base material subjected to an oxidation treatment such as alumite treatment. That is, the base material preferably includes an aluminum base material and an oxide layer formed on the aluminum base material. By providing such an oxide layer, the substrate has improved adhesion to the resin layer.

The thickness of the oxide layer is not particularly limited, but is preferably 5 to 15 μm, for example.

Next, the developing roller shown in FIGS. 5 and 6 will be described.

FIG. 5 is a perspective view showing another example of the developing roller provided in the developing device according to the embodiment of the present invention. FIG. 6 is a cross-sectional view of the developing roller shown in FIG.

The developing roller 231 includes a roller main body 52 and a resin layer 53 coated on the surface of the roller main body 52, as shown in FIGS. Examples of the roller body 52 include a roller 55 that is connected to a shaft 55 that is pivotally supported by the developing device by a plurality of ribs 58. The resin layer 53 can be the same as the resin layer 36. The roller body 52 corresponds to the base material 35, and the laminate 51 including the roller body 52 and the resin layer 53 corresponds to the rotating sleeve 32.

Further, the production method of the developing roller 231 is not particularly limited as long as the above-described developing roller can be produced. First, in the case of the developing roller shown in FIGS. 3 and 4, for example, the surface layer is first oxidized by subjecting an aluminum cylindrical base material generally used as a rotating sleeve of the developing roller to an alumite treatment. An alumite layer as a layer is formed. The diameter of the cylindrical substrate is not particularly limited, but is preferably 12 to 20 μm, for example. And the rotating sleeve in which this alumite layer was formed is heat-processed. By performing this heat treatment, cracks are formed in advance in the alumite layer in order to prevent new cracks from being formed in the alumite layer in the drying step described later when forming the resin layer. Although it will not specifically limit if this heat processing can form such a crack, For example, it is preferable to perform for a time longer than a drying process. Specifically, this heat treatment is preferably performed at 100 to 140 ° C. for 5 to 15 minutes. Next, the polyamide resin and the titanium oxide are mixed using an alcohol such as methanol as a dispersion medium. In that case, it is preferable that the mixing ratio of the polyamide resin and the titanium oxide is a ratio capable of realizing the content of the titanium oxide. The amount of alcohol used is not particularly limited as long as it can dissolve the polyamide resin. For example, it is preferably 200 to 900 parts by mass with respect to 100 parts by mass of the polyamide resin. The rotating sleeve subjected to the heat treatment is immersed in the liquid containing the polyamide resin and the titanium oxide thus obtained, and then the rotating sleeve is taken out of the liquid and dried. By such an immersion method, a resin layer can be formed on the surface of the rotating sleeve. This drying is not particularly limited as long as a resin layer can be formed on the surface of the rotating sleeve, but is preferably performed at 110 to 150 ° C. for 5 to 20 minutes, for example.

As described above, by using the developing roller 231 as a toner carrier in a developing device that performs leak detection or a touch-down developing type developing device, peeling of the resin layer is sufficiently suppressed, and a high level is maintained over a long period of time. A developing device capable of forming a high-quality image is obtained.

Hereinafter, the present invention will be described more specifically by way of examples. However, the scope of the present invention is not limited to these examples.

The image forming apparatus according to the example and the comparative example is obtained by replacing the developing roller of the developing device of the copying machine (TASKalfa 400ci manufactured by Kyocera Mita Corporation) with the following developing roller. The developing roller to be replaced is a developing roller having a resin layer on the surface as described later.

[Example 1]
First, the manufacturing method of the developing roller according to Example 1 is shown below.

As the developing roller, a developing roller having a resin layer on the surface as shown in FIGS. 3 and 4 was produced.

Specifically, first, an alumite layer having a thickness of 10 μm was formed on the surface layer by subjecting an aluminum sleeve having a diameter of 16 mm to an alumite treatment. And the sleeve in which this alumite layer was formed was heat-processed at 120 degreeC for 10 minute (s), and the crack was generated in the alumite layer.

Next, 100 parts by mass of a polyamide resin (Amilan CM8000 manufactured by Toray Industries, Inc.) having a repeating unit represented by the above formulas (1) to (4) and 100 parts by mass of titanium oxide (ET300W manufactured by Ishihara Sangyo Co., Ltd.) The mixture was added to 800 parts by mass of methanol, and mixed for 48 hours with a ball mill using zirconia beads having a diameter of 1 mm. The sleeve thus heat-treated was immersed in the liquid thus obtained, and then the sleeve was taken out of the liquid and dried at 130 ° C. for 10 minutes. The developing roller according to Example 1 was obtained by such an immersion method. The surface of the obtained developing roller was composed of a resin layer, and the thickness of the resin layer was 10 μm.

The developing roller was stored for 18 days in an environment of a temperature of 40 ° C. and a relative humidity of 90%, and then a peeling test described later was performed. This peel test is a method based on JIS K5600-5-6. Specifically, as the peeling test, first, the blade was applied to the resin layer of the obtained developing roller at a right angle and cut to the alumite layer of the base material at intervals of 5 mm, and five cuts were made. Formed. Thereafter, the direction of 90 ° was changed with respect to the cut formed by the cutting, and the resin layer was cut to the alumite layer of the base material in the same manner to form five cuts. By doing so, the resin layer was divided | segmented into the grid | lattice form of a 5 mm space | interval, and a total of 16 grid | lattice-like grid | lattices were formed. A cross-cut cello tape (24 mm wide cello tape (CT-24 manufactured by Nichiban Co., Ltd.)) defined in JIS K5600-5-6 was pasted on the formed lattice. Then, this cellophane was peeled off. At that time, the number of grid-like resin layers peeled off at the same time as the cellophane was peeled was measured.

As a result of this peel test, the number of peels was zero in the developing roller according to Example 1. That is, in the developing roller according to Example 1, the resin layer did not peel in this peel test.

Further, other configurations of the image forming apparatus, detailed development conditions, and the like are as follows.

As the photosensitive drum, an amorphous silicon photosensitive member (a-Si photosensitive member) was used, rotated at a peripheral speed (drum linear speed) of 150 mm / second, and the surface potential was set to 270 V on the white background and 20 V on the image portion. .

As the developing roller, the developing roller was used, and adjacent peripheral surfaces rotated in the same direction (with rotation) with respect to the rotation of the photosensitive drum, and the peripheral speed ratio was set to 1.5.

As the magnetic roller, a magnetic roller having a fixed magnet inside and an outer cylinder portion made of a rotatable aluminum base material and having an alumite treatment on the surface thereof was used. Further, the magnetic rollers have their peripheral surfaces rotating in the opposite direction (counter rotation) with respect to the rotation of the developing roller, and the peripheral speed ratio is 1.1.

The distance between the photosensitive drum and the developing roller (DS distance) was 120 μm, and the distance between the developing roller and the magnetic roller (MS distance) was 300 μm.

The developing roller has a peak-to-peak value Vpp (slv) of 1500 V, a bias voltage Vdc (slv) of 50 V, a duty ratio Vduty (slv) of 45%, and a frequency f (slv) of 3.7 kHz. A superimposed voltage in which an AC component is superimposed on a DC component was applied.

The magnetic roller has a bias voltage Vdc (mag) such that the potential difference of the DC component between the developing roller and the magnetic roller is 200 to 400 V (variable), and the duty ratio of the AC component between the developing roller and the magnetic roller. Satisfies the duty ratio Vduty (mag) such that the frequency becomes 70% and the frequency f (mag) such that the frequency of the AC component between the developing roller and the magnetic roller is 3.7 kHz. The superimposed voltage was applied.

As the toner and developer, the toner and developer used in the above copying machine (TASKalfa 400ci manufactured by Kyocera Mita Corporation) were used. Specifically, a positively chargeable toner having an average particle size of 6.8 μm was used as the toner.

Also, when leak detection is performed, leak detection is performed when the power is turned on and every 300 printed sheets.

[Comparative Example 1]
As a liquid used when manufacturing the developing roller, 100 parts by mass of urethane resin (Desmophene manufactured by Sumika Bayer Urethane Co., Ltd.), 100 parts by mass of titanium oxide (ET300W manufactured by Ishihara Sangyo Co., Ltd.), and 6 parts by mass of carbon black Was added to 300 parts by mass of methyl ethyl ketone, and a liquid obtained by mixing for 48 hours with a ball mill using zirconia beads having a diameter of 1 mm was used in the spray method, except that a developing roller was produced. It is the same. The resin layer had a thickness of 10 μm.

When the above peeling test was performed on the developing roller according to Comparative Example 1, 13 of 16 peelings were confirmed.

[Comparative Example 2]
As a polyamide resin, it is the same as that of Example 1 except having used the polyamide resin (X1010 by Daicel-Evonik Co., Ltd.) shown to following formula (5). The resin layer had a thickness of 10 μm.

When the above peeling test was carried out on the developing roller according to Comparative Example 2, peeling of 2 pieces out of 16 pieces was confirmed.

[Evaluation]
Under the above development conditions, the peak-to-peak value Vpp (mag) was changed, and the AC voltage (AC bias between MS) between the development roller and the magnetic roller was changed to the temperature shown in Table 1 below. Images were formed in a normal temperature and humidity environment of 20 to 23 ° C. and relative humidity of 50 to 65% RH.

(Peeling)
Under the above conditions, after forming 500,000 images intermittently on 3 sheets, visually check the developing roller, and if the peeling of the resin layer cannot be confirmed, it is evaluated as “O” and the peeling of the resin layer is confirmed. If it was, it was evaluated as “×”.

(ghost)
After printing a specific image, it was printed on a halftone image. It was visually confirmed whether or not a ghost in which a specific image printed previously was thinly generated occurred in the printed halftone image. If a ghost could not be confirmed, it was evaluated as “◯”, and if a ghost was confirmed, it was evaluated as “x”.

The production conditions and development conditions of the developing roller in each Example and Comparative Example are shown in Table 1 together with the results of the peel test on the developing roller according to each Example and Comparative Example and the results of the above evaluation.

As can be seen from Table 1, when using a developing roller in which the resin layer did not peel in the peel test (Example 1), using a developing roller in which peeling occurred in the peel test (Comparative Example 1 and Unlike Comparative Example 2), even when 500,000 sheets were printed intermittently, the resin layer did not peel off.

This is because the touch-down developing device does not cause peeling of the resin layer even if the AC bias between MSs is increased to the extent that no ghost occurs, and even if leak detection is performed, peeling of the resin layer does not occur. .

On the other hand, when the developing roller according to Comparative Example 1 and Comparative Example 2 in which peeling occurred in the above peeling test is used, the AC bias between MSs is such that ghost is generated, and leak detection is performed. Otherwise, peeling of the resin layer did not occur. However, when the AC bias between MSs was increased to such an extent that no ghost was generated, the resin layer was peeled off. Further, even when the MS-to-MS AC bias is such that a ghost is generated, the resin layer is peeled off only by performing leak detection.

From the above, it was found that a suitable image can be formed over a long period of time by using a developing roller in which the resin layer was not peeled off in the peel test as the toner carrier.

Further, the adhesion in the developing roller according to Example 1 is considered to be due to the fact that the base material is first subjected to an alumite treatment. It is thought that the anchor effect by the fine holes of the alumite layer enhances the adhesion with the resin layer formed thereon.

Moreover, since the polyamide resin contained in the resin layer has a repeating unit having 8 or less carbon atoms per amide bond, it is considered that this amide bond suitably forms a hydrogen bond with the metal of the base material. It is done. For this reason, it is thought that the adhesiveness of this resin layer and a base material increases.

From these facts, the developing roller according to Example 1 does not cause peeling in the peeling test, and even when used as a toner carrier provided in a developing device in which peeling of the resin layer easily occurs, It is considered that no peeling occurs.

This application is based on Japanese Patent Application No. 2014-087300 filed on April 21, 2014, the contents of which are included in the present application.

In order to express the present invention, the present invention has been described above and properly through the embodiments. However, those skilled in the art can easily change and / or improve the above-described embodiments. Should be recognized. Accordingly, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not limited to the scope of the claims. To be construed as inclusive.

Claims

A toner carrier for supplying toner to the image carrier, which is disposed on the surface of the image carrier on which an electrostatic latent image is formed in a non-contact manner;
A bias applying unit that applies a developing bias to the toner carrier and supplies the toner carried on the surface of the toner carrier to the image carrier;
Applying a leak generating voltage to the toner carrier to generate a leak between the image carrier and the toner carrier;
A leak detection unit for detecting a leak generated by the leak generation unit;
A bias control unit for setting the development bias based on a leak occurrence voltage when a leak is detected by the leak detection unit;
The toner carrier includes a base material and a resin layer formed on the base material,
In the adhesion test by the cross-cut method, the resin layer is cut to the base material in the thickness direction so that the resin layer is divided into a grid shape with an interval of 5 mm, and an adhesive tape is applied to the resin layer cut into the grid shape. The developing device is characterized in that the cut resin layer does not peel from the base material when peeled after being adhered.
The resin layer includes an alcohol-soluble polyamide resin and a conductive material dispersed in the polyamide resin,
The developing device according to claim 1, wherein the conductive material is made of titanium oxide.
3. The developing device according to claim 2, wherein the polyamide resin has a repeating unit having 8 or less carbon atoms per amide bond.
3. The developing device according to claim 2, wherein the resin layer is a layer formed by immersing the base material in a liquid containing the polyamide resin and the conductive material.
2. The developing device according to claim 1, wherein the substrate comprises an aluminum-based substrate and an oxide layer formed on the aluminum-based substrate.
An image forming apparatus comprising the developing device according to claim 1 and the image carrier.
A toner carrier for supplying toner to the image carrier, which is disposed on the surface of the image carrier on which an electrostatic latent image is formed in a non-contact manner;
A developer carrier for supplying toner contained in the two-component developer to the toner carrier from a two-component developer containing toner and carrier carried on the surface;
A first bias applying unit that applies a first developing bias to the toner carrier and supplies the toner carried on the surface of the toner carrier to the image carrier;
A second bias applying unit that applies a second developing bias to the developer carrying member and supplies the toner contained in the two-component developer carried on the surface of the developer carrying member to the toner carrying member; Prepared,
The toner carrier includes a base material and a resin layer formed on the base material,
In the adhesion test by the cross-cut method, the resin layer is cut to the base material in the thickness direction so that the resin layer is divided into a grid shape with an interval of 5 mm, and an adhesive tape is applied to the resin layer cut into the grid shape. The developing device is characterized in that the cut resin layer does not peel from the base material when peeled after being adhered.
The AC electric field strength between the toner carrier and the developer carrier is 6000 to 12500 V / mm as a ratio to the distance between the toner carrier and the developer carrier. Development device.
The resin layer includes an alcohol-soluble polyamide resin and a conductive material dispersed in the polyamide resin,
The developing device according to claim 7, wherein the conductive material is made of titanium oxide.
10. The developing device according to claim 9, wherein the polyamide resin has a repeating unit having 8 or less carbon atoms for one amide bond.
The developing device according to claim 9, wherein the resin layer is a layer formed by immersing the base material in a liquid containing the polyamide resin and the conductive material.
The developing device according to claim 7, wherein the substrate includes an aluminum-based substrate and an oxide layer formed on the aluminum-based substrate.
An image forming apparatus comprising the developing device according to claim 7 and the image carrier.