JP5162140B2 - Developing device in image forming apparatus - Google Patents

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, and more particularly, it can be detached from the main body of the image forming apparatus and has a simple structure. The present invention relates to a developing device in an image forming apparatus having a bias power supply member.

  In an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine using an electrophotographic system, a developing device is used to develop a latent image formed on a photoreceptor. This developing device includes a developing roller that carries a developer and faces the photoreceptor, a magnetic roller having a fixed magnet inside, a layer thickness regulating member that regulates the developer layer thickness, and a developer accumulated in a developing tank. In order to move the developer, the biasing power is supplied to the developing roller, the magnetic roller, the layer thickness regulating member, and the like.

  Many of these developing devices are cartridge type and can be attached to and detached from the main body of the image forming apparatus. When such a developing device is attachable and detachable, the image forming apparatus main body and the cartridge type developing device are contacted to supply bias power. When a member is prepared and the developing device is mounted on the image forming apparatus main body, a bias power can be supplied from the image forming apparatus main body side.

  When power is supplied to the developing roller, magnetic roller (supply roller), blade, etc. from the contact point provided in the developing device, a bias electrode made of stainless steel wire for piano wire spring material, phosphor bronze wire, etc. There is a method of making one end into a coil spring shape, but this method is difficult to attach to the developing device. In addition, in the method of pressing the electrode plate or feeding the bias power source using the coil springs at both ends in the longitudinal direction of the developer carrier, a structure where the coil springs are inserted is necessary, and the usable places are limited. The electrode structure using a leaf spring requires a sheet metal processing, which increases the cost accordingly.

  For this reason, for example, in Patent Document 1, a single contact from the apparatus main body side supplies different voltages to the developing roller and the toner layer thickness regulating member, and therefore contacts the contact provided on the image forming apparatus main body side. A coil spring is provided, the coil spring and the developing roller are connected by a wire, a power source is directly applied to the developing roller, and the toner layer thickness regulating member is coupled to the coil spring and the toner layer thickness regulating member via a Zener diode in the middle. And an image forming apparatus in which a power supply voltage is lowered by a Zener diode so that a voltage suitable for the toner layer thickness regulating member can be applied.

  Patent Document 2 discloses a first contact member electrically connected to a rotating shaft of a developing roller, a second contact member electrically connected to a rotating shaft of a supply roller, a cover member attached to a side surface of the developing device. A developing device is disclosed in which a third contact member electrically connected to a support plate of a blade is formed and fixed with a wire, and each wire is bent to form a contact portion with respect to an image forming apparatus main body.

JP-8-248767 discloses JP 2005-70402 A

  However, the image forming apparatus disclosed in Patent Document 1 is for supplying different voltages to the developing roller and the toner layer thickness regulating member with a single contact formed by a coil spring. Wires connected to the toner layer thickness regulating member need to be connected separately, and accordingly, man-hours for wiring and connection are required.

  Further, in the developing device disclosed in Patent Document 2, a contact made of a wire is simply brought into contact with each of the developing roller, the supply roller, and the blade, and each wire is bent to provide a contact portion for the image forming apparatus main body. By simply forming, the number of parts increases accordingly, the number of man-hours for processing each wire increases, and the incidence of contact failure increases accordingly.

  On the other hand, as described in Patent Document 2, the method of making one end of a bias electrode made of a stainless steel wire for a piano wire spring material, a phosphor bronze wire, etc. in a coil spring shape is difficult to mount, and the electrode plate In the method in which a bias power source is fed using a coil spring at both ends in the longitudinal direction of the developer carrier, a structure in which the coil spring is inserted is necessary, and the usable place is limited. The structure requires a mold or sheet metal processing, which increases costs.

  Therefore, in the present invention, the image forming apparatus main body is reliably brought into contact with the contact point, and power is supplied to the developing roller, the magnetic roller (supply roller), the developer layer thickness regulating member, and the like. Even when supplying the same voltage to a thickness regulating member or the like, it is an object to provide a developing device in an image forming apparatus that can supply power reliably with a simple configuration without increasing the number of parts.

In order to solve the above problems, the developing device in the image forming apparatus according to the present invention is:
A developing device configured to be detachable from the image forming apparatus main body,
The developing device has a developing roller that faces a photoconductor on which a latent image is formed by an electrophotographic method, carries a developer, and a rotating sleeve that faces the developing roller and includes a fixed magnet. A magnetic roller for supplying developer to the roller, and a developer layer thickness regulation extending in the axial direction at a predetermined interval from the magnetic roller on the upstream side of the rotation position of the magnetic roller facing the developing roller A developing device in an image forming apparatus in which a bias power is supplied from the image forming apparatus main body to the magnetic roller, the developer layer thickness regulating member, and the developing roller.
On one side of the conductive elastic member, a planar contact portion that contacts the contact of the image forming apparatus main body, and a pressing portion that presses the planar contact portion in the contact direction provided in the image forming apparatus main body, A coil-like portion to be fitted on the shaft of the developing roller or the magnetic roller is formed on the other side, and bias power is supplied from the image forming apparatus main body through the planar contact portion.

  Thus, in order to supply bias power from the image forming apparatus main body to the developing device, for example, a planar contact portion formed like a mosquito coil, a pressing portion that presses the planar contact portion, and a shaft of the developing roller or magnetic roller By forming the coiled portion to be fitted and supplying power, the contact on the image forming apparatus main body side can be reliably brought into contact with the contact because the planar contact portion is pressed by the pressing portion. Since the coiled portion is fitted to the shaft for the developing roller and the magnetic roller, it is possible to reliably supply power to the shaft. If the conductive elastic member is a linear spring member, there is no need for a metal mold or sheet metal processing unlike a plate spring, and it can be easily processed to form a coiled portion or a planar contact portion. In the case of a configuration, the sheet metal width is generally required to be 3 mm or more, but in the case of a linear spring member, it may be about 0.3 mm to 0.5 mm, and the degree of freedom can be increased in terms of space. The contact point can be surely fitted to the shaft.

  In addition, the conductive elastic member is formed with a coiled portion that is fitted into a terminal portion provided on the developer layer thickness regulating member and has an inner diameter smaller than the terminal portion diameter, for example, a magnetic roller and a developer layer. When power is supplied while keeping the thickness regulating member at the same potential, it is not necessary to provide a special contact for the developer layer thickness regulating member, and the assembly of the developing device can be simplified, and the cost increase can be suppressed accordingly.

  Further, the pressing portion that presses the planar contact portion is formed in a coil shape, and the pressing portion is provided in the developing device and is held by a holding portion that surrounds and fits the pressing portion, The coiled portion to be fitted to the shaft of the developing roller or magnetic roller has an inner diameter smaller than the shaft diameter, and a protective cover for covering the coiled portion is provided, so that the pressing portion is securely attached to the developing device. It is also possible to prevent accidents such as accidental touching the coiled portion and electric shock.

  As described above, according to the present invention, the planar contact portion formed on one side of the conductive elastic member is pressed against the image forming apparatus main body side contact by the pressing portion, and is formed on the other side of the shaft of the developing roller or magnetic roller. Since the coiled portion is firmly fitted, power supply from the image forming apparatus main body can be reliably performed to the developing roller or the magnetic roller.

  Further, for example, even when power is supplied while the magnetic roller and the developer layer thickness regulating member are at the same potential, the developer layer thickness regulating member is formed on the conductive elastic member formed with the planar contact portion and the coil-like portion. By forming a coil-like part that fits into the terminal part, it is possible to supply power without the need to provide a special contact for the developer layer thickness regulating member, and assembling of the developing device is also simplified. Cost increase can be suppressed.

  In addition, by providing a holding part and protective cover for the pressing part and coiled part, it is possible to prevent accidents such as mounting the contact part to the developing device reliably or touching it accidentally. it can.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  First briefly described an overview of the present invention to. The developing device according to the present invention includes a developing roller, a magnetic roller (supply roller), a developer layer thickness regulating member, a stirring member for stirring the developer, and the like. Bias power is supplied from the apparatus main body to the developing roller, the magnetic roller, and the developer layer thickness regulating member.

  In order to reliably supply a bias to the developing roller, magnetic roller, and developer layer thickness regulating member of the detachable developing device, a linear conductive spring member (conductive elastic member) is used, and one end of the mosquito coil is used. A planar contact portion formed in a shape and a coil-shaped pressing portion that presses the planar contact portion in the contact direction of the image forming apparatus main body are formed. In addition, a coiled portion having an inner diameter slightly smaller than the shaft diameter of the developing roller or the magnetic roller is formed at the other end portion or in the middle thereof, thereby contacting the contact of the image forming apparatus main body with the developing roller or the magnetic roller. It was to perform the power supply to.

  In addition, when a bias having the same potential is supplied to the magnetic roller and the developer layer thickness regulating member, the developer layer thickness regulating member is provided on the conductive spring member (conductive elastic member) for feeding the magnetic roller. A coil-shaped portion having a diameter slightly smaller than the terminal diameter was formed, so that power can be supplied to the developer layer thickness regulating member.

  Further, the developing device is provided with a holding portion that surrounds and fits the pressing portion with respect to the coiled pressing portion, and the coiled portion with respect to the coiled portion that is fitted to the shaft of the developing roller or the magnetic roller. A protective cover is provided to cover and cover the part, so that the pressing part can be securely attached to the developing device, and accidents such as accidental touching the coiled part can be prevented. .

  In this way, by forming a contact with a linear conductive spring member, for example, in the case of a sheet metal configuration, generally 3 mm or more is required as the width of the sheet metal, but in the case of a linear conductive spring member, It may be about 0.3 mm to 0.5 mm, and there is an advantage that the degree of freedom can be increased in terms of space.

  The above is the outline of the developing device in the image forming apparatus according to the present invention. The present invention will be described below in more detail with reference to the drawings. In the following description, the present invention is described using a two-component developer having a magnetic carrier and a toner, a developing roller facing a photoconductor on which a latent image is formed by an electrophotographic method, and a developer on the developing roller. An example of a developing device in which a magnetic roller to be supplied and a stirring member are rotatably arranged in a casing and a developer layer thickness regulating member is provided will be described. However, the present invention is not limited to the above-described type of developing device. is clear that the possible application of the developing device of the embodiment.

  First, with reference to FIG. 6, an outline of the photosensitive member and the developing device constituting the image forming apparatus will be described. The developing device shown in FIG. 6 is a diagram schematically showing an example of a developing device that develops an electrostatic latent image formed on the photosensitive drum 17 using a two-component developer having a magnetic carrier and toner. is there. The illustrated image forming apparatus includes, for example, a photosensitive drum 17 using an amorphous silicon (a-Si) -based material, and around the photosensitive drum 17, a charger 16, a developing device 10, a transfer device ( transfer roller) 19 and a cleaning device 21, etc. are arranged.

  After the surface of the photoconductive drum 17 is uniformly charged by the charger 16, the surface of the photoconductive drum 17 is exposed according to the image data by the exposure device 18, thereby forming an electrostatic latent image on the photoconductive drum 17. Is done. The electrostatic latent image is developed by the developing device 10 to become a toner image, and is transferred onto the paper 22 conveyed to the nip portion between the transfer roller 19 and the photosensitive drum 17. Then, the paper 22 is conveyed to a fixing device (not shown), where the toner image is fixed on the paper 22 and then discharged onto a paper discharge tray, for example. The toner remaining on the photosensitive drum 17 is removed by the cleaning device 21.

  The developing device 10 includes a developing device housing 20, and a two-component developer is stored in the developing device housing 20. Further, in the developing device casing 20, stirring rollers (mixers) 11 and 12 are arranged in parallel near the bottom of the casing with the longitudinal direction as an axial direction, and the two-component developer is charged while being stirred and conveyed. A partition wall 201 erected from the bottom of the housing is provided in the axial direction between the stirring rollers 11 and 12, and a magnetic roller 14 is disposed above the stirring roller 11 in the figure. A developing roller (developing roller) 15 is arranged facing the magnetic roller 14, and the developing roller 15 faces the photosensitive drum 17 facing the opening side of the developing device housing 20.

  The magnetic roller 14 has a non-magnetic rotating sleeve 14b containing a fixed magnet roller body 14a having a plurality of magnetic poles. For example, the rotating sleeve 14b is driven to rotate in the direction indicated by the solid line arrow in the figure. The developing roller 15 has a rotating sleeve 15a, and the rotating sleeve 15a is opposite to the rotating sleeve 14b at the position facing the magnetic roller 14 (opposed position) (the rotating sleeve 15a). the direction of rotation is indicated by solid arrows in the drawing).

  In the developing device casing 20, the layer developer layer thickness regulating member 13 is disposed on the upstream side of the magnetic roller 14 with respect to the position facing the developing roller 15. is mounted along the direction) extending back from. A slight gap (gap) is formed between the tip of the developer layer thickness regulating member 13 and the surface of the rotating sleeve 14b.

  In the developing device 10 shown in FIG. 6, the two-component developer is circulated through the developing device housing 20 while being stirred by the stirring rollers 11 and 12, and the toner is charged and the two-component developer on the stirring roller 11 is charged. Is attracted and conveyed by the magnetic roller 14 located on the upper side. The sucked two-component developer forms a magnetic brush (not shown) on the magnetic roller 14, and the magnetic brush is regulated in layer thickness by the developer layer thickness regulating member 13, so that the magnetic roller 14 and the developing roller 15 in the potential difference between forming a toner layer on the developing roller 15. Then, the electrostatic latent image on the photosensitive drum 17 is developed by the toner layer on the developing roller 15.

  After the development is performed in this way, the remaining toner layer that is not used for the development on the developing roller 15 is closest to the magnetic roller 14 at the position facing the magnetic roller 14, and the two-component development is performed at this facing position. The toner is scraped off by the mechanical force of the magnetic brush by the agent, and the toner is developed from the developer layer on the magnetic roller 14 according to the potential difference (that is, the electric field) formed between the magnetic roller 14 and the developing roller 15. It is supplied to the roller 15 side.

  FIG. 5 is an external perspective view of the developing device 10 in the image forming apparatus according to the present invention, in which 15 is the developing roller described above, and 141 is a cover for protecting a contact for applying a voltage to the shaft of the magnetic roller 14. 131 and 112 are provided at the end of the developer layer thickness regulating member 13 and are hook-like terminals for applying a voltage to make the same potential as the magnetic roller 14, and 111 and 112 rotate the stirring rollers (mixers) 11 and 12. A gear mechanism 23 is a developer supply port to the developing device casing 20, but the other members described in FIG. 6 are covered and hidden by the developing device casing 20.

  FIG. 1 shows a connection state of a contact member constituted by a linear conductive spring member for supplying bias power to a doctor blade 13 and a magnetic roller 14 constituting a developing device in an image forming apparatus according to the present invention. It is a perspective view.

  As described above, the bias power supply member in the developing device according to the present invention is composed of the conductive linear conductive spring member (conductive elastic member) 30, and is in contact with the contact point of the image forming apparatus main body. A planar contact portion 301 formed in the shape of a mosquito coil and a coil-shaped pressing portion 302 that presses the planar contact portion 301 in the contact direction provided in the image forming apparatus main body are formed. In addition, a coiled portion 304 having an inner diameter slightly smaller than the shaft diameter of the magnetic roller 14 (or the developing roller 15) is formed at the other end portion of the linear conductive spring member 30 or in the middle thereof. The coiled portion 304 is fitted into the shaft so as to supply power to the magnetic roller 14 (or the developing roller 15).

  In addition, when a bias having the same potential is supplied to the magnetic roller 14 and the developer layer thickness regulating member 13, the developer layer thickness regulating member 13 is provided on the linear conductive spring member 30 that feeds the magnetic roller 14. A close-fitting coil-shaped portion having an inner diameter slightly smaller than the maximum width of the terminal 131 is formed so as to be fitted to the hook-shaped terminal 131, so that the developer layer thickness regulating member 13 can be fed by being fitted into the terminal 131. did.

  By doing so, the planar contact portion 301 is pressed in the contact direction of the image forming apparatus main body by the coiled portion (pressing portion) 302, and the planar contact portion 301 is reliably brought into contact with the contact of the image forming apparatus main body. be able to. Further, since the coiled portion 304 is fitted to the shaft of the roller with respect to the developing roller 15 and the magnetic roller 14, the shaft can be tightened by the coiled portion 304 to provide a reliable contact. Further, when a bias having the same potential is supplied to the magnetic roller 14 and the developer layer thickness regulating member 13, the coil-shaped portion 303 is fitted to the hook-shaped terminal 131 of the developer layer thickness regulating member 13. Power can be reliably supplied to the thickness regulating member 13, and power can be reliably fed to the developing roller 15, the magnetic roller 14, and the developer layer thickness regulating member 13 from the contact point of the image forming apparatus main body.

  FIG. 2 is a perspective view showing a state in which a developing device side member for positioning a coil-shaped portion of the contact member constituted by the linear conductive spring member described above is added.

  As is apparent from FIG. 1, the planar contact portion 301 and the coil-shaped pressing portion 302 cannot be reliably brought into contact with the image forming apparatus main body side contact unless there is a structure for holding them in the periphery. Further, when the coiled portion 304 is also exposed, there is a possibility of electric shock if a person touches it by mistake.

  FIG. 2 shows a structure for preventing this, and the planar contact portion 301 and the coiled pressing portion 302 are provided on the casing 20 of the developing device 10 and are coiled pressing portions 302. Is held by the holding portion 40 to be fitted and fitted. That is, the holding portion 40 is formed so that the entrance into which the coiled pressing portion 302 is fitted is slightly smaller than the outer diameter of the coiled pressing portion 302, and the portion that holds the inner coiled pressing portion 302 is coiled. It is formed to have the same diameter as the outer diameter of the pressing portion 302 or slightly smaller.

  Therefore, when the coil-shaped pressing portion 302 is pushed into the holding portion 40, the coil-like pressing portion 302 is not easily detached but is held, and the planar contact portion 301 can be pressed against the contact of the image forming apparatus main body (not shown). A holding unit 41 provided next to the holding unit 40 is a holding unit that holds a coil-shaped pressing unit (not shown) that supplies bias power to the developing roller 15.

  FIG. 3 is a perspective view of the state in which the coil-shaped pressing portion 302 is fixed to the holding portion 40 as viewed from the lower part of the developing device 10. As can be seen from FIG. 3, the planar winding portion 301 protrudes below the holding portion 40, and when the developing device 10 is attached to the image forming apparatus main body, it can be reliably brought into contact with the image forming apparatus main body side contact. And since the contact pressure can also be adjusted by the coil-shaped press part 302, it can be set as a suitable contact.

  Returning again to FIG. 2, the coiled portion 304 to be fitted to the shaft of the magnetic roller 14 is spaced from the coiled portion 304 and is moved up and down by the protective portion 42 formed in a “U” shape of Katakana. It is surrounded.

  In addition, as shown in FIG. 4 in which a member covering the coiled portion 304 is attached, the coiled portion 304 is covered with a protective cover 141 made of an insulating material having an inner diameter slightly smaller than the outer diameter of the coiled portion 304. This prevents electric shock when a person touches it by mistake.

  In the above description, the coil-shaped portion 303 that is a power feeding portion to the developer layer thickness regulating member 13 is interposed between the coil-shaped portion (pressing portion) 302 and the coil-shaped portion 304 following the planar winding portion 301. Of course, this order may be reversed as long as it can be tied in the shortest time.

  Although the image forming apparatus main body side contact is not mentioned, the main body side contact may be formed by a cutting pin or a leaf spring, or may be a linear conductive spring member. However, in the case of a linear conductive spring member, it is necessary to devise such as making the main body side contact into a flat winding so as not to get entangled with the flat winding portion 301.

  As described above, according to the present invention, the planar contact portion formed on one side of the conductive elastic member is pressed against the image forming apparatus main body side contact by the pressing portion, and the shaft of the developing roller or magnetic roller is Since the coiled portion formed on the other side is firmly fitted, power supply from the image forming apparatus main body can be reliably performed to the developing roller or the magnetic roller.

  Further, for example, even when power is supplied while the magnetic roller and the developer layer thickness regulating member are at the same potential, the developer layer thickness regulating member is formed on the conductive elastic member formed with the planar contact portion and the coil-like portion. By forming a coil-like part that fits into the terminal part, it is possible to supply power without the need to provide a special contact for the developer layer thickness regulating member, and assembling of the developing device is also simplified. Cost increase can be suppressed.

  In addition, by providing a holding part and protective cover for the pressing part and coiled part, it is possible to prevent accidents such as mounting the contact part to the developing device reliably or touching it accidentally. it can.

  According to the present invention, the bias power supply in the developing device that can be attached to and detached from the image forming apparatus main body can be reliably performed with a simple configuration without increasing the number of components, and the image forming apparatus can be provided at low cost. be able to.

The connection state of the contact member comprised with the linear electroconductive spring member is shown for the bias power supply to the developer layer thickness control member 13 and the magnetic roller 14 which comprise the developing device in the image forming apparatus which becomes this invention. It is a perspective view. It is the perspective view which showed the state which added the developing device side member which positions the site | part comprised by the coil shape of the contact member formed with the linear electroconductive spring member in the developing device which becomes this invention. FIG. 5 is a perspective view of a connecting portion of a contact member formed of a linear conductive spring member with an image forming apparatus main body side contact in the developing device according to the present invention as viewed from the lower part of the developing device. FIG. 3 is a perspective view of an end portion of the developing device equipped with a member covering a contact member constituted by a linear conductive spring member in the developing device according to the present invention. 1 is an external perspective view of a developing device in an image forming apparatus according to the present invention. FIG. 2 is a diagram for explaining an outline of a photoconductor and a developing device constituting an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developing apparatus 13 Developer layer thickness control member 131 Hook-shaped terminal 14 Magnetic roller 141 Protective cover 15 Developing roller 23 Developer supply port 30 Linear conductive spring member 301 Flat wound portion 302 Coiled portion (pressing portion)
303 Coiled part 304 Coiled part 40, 41 Holding part 42 of the coiled pressing part 302 constituting the first contact part Protection part of the coiled part 304 constituting the second contact part

Claims (3)

A developing device configured to be detachable from the image forming apparatus main body,
The developing device has a developing roller that faces a photoconductor on which a latent image is formed by an electrophotographic method, carries a developer, and a rotating sleeve that faces the developing roller and includes a fixed magnet. A magnetic roller for supplying developer to the roller, and a developer layer thickness regulation extending in the axial direction at a predetermined interval from the magnetic roller on the upstream side of the rotation position of the magnetic roller facing the developing roller A developing device in an image forming apparatus in which a bias power is supplied from the image forming apparatus main body to the magnetic roller, the developer layer thickness regulating member, and the developing roller.
On one side of the conductive elastic member, a planar contact portion that contacts the contact of the image forming apparatus main body, and a pressing portion that presses the planar contact portion in the contact direction provided in the image forming apparatus main body, Forming a coil-like portion to be fitted to the shaft of the developing roller or magnetic roller on the other side, supplying a bias power from the image forming apparatus main body via the planar contact portion ,
A developing device in an image forming apparatus , wherein a coil-like portion having an inner diameter smaller than the diameter of the terminal portion is formed in the conductive elastic member by being fitted into a terminal portion provided on the developer layer thickness regulating member . A developing device configured to be detachable from the image forming apparatus main body,
The developing device has a developing roller that faces a photoconductor on which a latent image is formed by an electrophotographic method, carries a developer, and a rotating sleeve that faces the developing roller and includes a fixed magnet. A magnetic roller for supplying developer to the roller, and a developer layer thickness regulation extending in the axial direction at a predetermined interval from the magnetic roller on the upstream side of the rotation position of the magnetic roller facing the developing roller A developing device in an image forming apparatus in which a bias power is supplied from the image forming apparatus main body to the magnetic roller, the developer layer thickness regulating member, and the developing roller.
On one side of the conductive elastic member, a planar contact portion that contacts the contact of the image forming apparatus main body, and a pressing portion that presses the planar contact portion in the contact direction provided in the image forming apparatus main body, Forming a coil-like portion to be fitted to the shaft of the developing roller or magnetic roller on the other side, supplying a bias power from the image forming apparatus main body via the planar contact portion,


The pressing portion that presses the planar contact portion is formed in a coil shape, and the pressing portion is held by a holding portion that is provided in the developing device and surrounds and fits the pressing portion. developing apparatus in images forming apparatus you. A developing device configured to be detachable from the image forming apparatus main body,
The developing device has a developing roller that faces a photoconductor on which a latent image is formed by an electrophotographic method, carries a developer, and a rotating sleeve that faces the developing roller and includes a fixed magnet. A magnetic roller for supplying developer to the roller, and a developer layer thickness regulation extending in the axial direction at a predetermined interval from the magnetic roller on the upstream side of the rotation position of the magnetic roller facing the developing roller A developing device in an image forming apparatus in which a bias power is supplied from the image forming apparatus main body to the magnetic roller, the developer layer thickness regulating member, and the developing roller.
On one side of the conductive elastic member, a planar contact portion that contacts the contact of the image forming apparatus main body, and a pressing portion that presses the planar contact portion in the contact direction provided in the image forming apparatus main body, Forming a coil-like portion to be fitted to the shaft of the developing roller or magnetic roller on the other side, supplying a bias power from the image forming apparatus main body via the planar contact portion,
The developing roller or coiled portion fitted on the shaft of the magnetic roller is smaller inner diameter than the shaft diameter, the developing device in the images forming apparatus it wherein a protective cover covering the coil-shaped portion is provided .

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