JP2009025370A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of achieving stable coating layer regulation and triboelectrification for toner while avoiding deterioration of image quality such as a white stripe. <P>SOLUTION: A regulation member 4 includes a sheet type elastic member 4a abutting on a developing roller 3, and supporting members 4b provided respectively on an upstream side and a downstream side in the rotating direction of the developing roller 3 with reference to an abutting part 9 between the developing roller 3 and the sheet type elastic member 4a, and supporting the sheet type elastic member 4a. In a simplex state of the regulation member 4 where the sheet type elastic member 4a does not abut on the developing roller 3, the sheet type elastic member 4a is supported by the supporting members 4b in such a state that tension acts. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device used in an electrophotographic image forming apparatus.

  As a conventional developing method using a single component toner, a contact developing method and a non-contact developing method are widely used. As the developer carrying member, an elastic roller is generally used in the contact development method, and an elastic roller or a metal sleeve is generally used in the non-contact development method.

  On the developer carrying member, there is provided a developer regulating member that comes into contact with the developer carrying member for the purpose of regulating the coat of the developer and imparting electrification by friction.

  As the developer regulating member, (1) a cantilever type plate-shaped developer regulating member, (2) a developer regulating member using a both-end supported sheet-like elastic member, and the like are proposed.

<(1) Development Method Using a Cantilever-Type Plate-Shaped (Cantilever Blade-Shaped) Developer Restricting Member>
FIG. 11 shows a contact development method using non-magnetic one-component toner, and an elastic roller having a dielectric layer is used as a developer carrying member. The supply of the developer to the developing roller 103 as the developer carrying member is performed by a supply roller 105 that rotates in contact with the developing roller 103. The supply roller 105 transports the developer from within the developing unit and adheres it to the developing roller 103, and also has a function of temporarily removing the developer remaining on the developing roller 103 without moving to the photosensitive member.

  The developer adhering to the developing roller 103 is subjected to coating layer regulation and charge application by frictional charging by a cantilever type plate-like regulating member 104a as a developer regulating member. Here, the developer regulating member is composed of a metal thin plate that contacts the developing roller 103 or a metal thin plate having a resin layer on the surface, and a support metal plate that adheres and supports the metal thin plate.

  On the other hand, FIG. 12 shows a non-contact developing method using a magnetic one-component toner, and a developing sleeve 108 having a resin layer on an aluminum base tube is used as a developer carrier. The developer is supplied to the developing sleeve 108 using a magnetic force by a fixed magnet roller 107 provided inside the developing sleeve.

  Here, a cantilever type plate-shaped regulating member 104a as a developer regulating member that performs charge regulation by the coating layer regulation and frictional charging of the developer adhered to the developing sleeve 108 is a plate-shaped rubber that contacts the developing sleeve 108. And a support sheet metal that adheres and supports this.

  On the developer carrier, the developer that has been subjected to coat regulation and charge application is caused by the difference in potential between the electrostatic latent image formed on the latent image carrier and the bias applied to the developer carrier. The latent image on the carrier is developed.

<(2) Development Method Using Developer Regulating Member Using Both-end-type Sheet-like Elastic Member>
Patent Document 1 proposes a method in which a sheet-like elastic member is supported at both ends instead of the cantilever blade-shaped developer regulating member described above, and a developer carrier is abutted between the support portions. FIG. 13 shows a developing device using a developer regulating member 104 that is a double-supported sheet-like elastic member.
Japanese Patent Laid-Open No. 11-265115

  However, in the blade-shaped regulating member (1), the toner needs to be frictionally charged in a short time by the regulating member and the developer carrying member. Therefore, when the toner coating layer regulation and frictional charging are performed by contacting the regulating member and the developer carrier, the nip width of the abutting portion is narrow, and therefore it is necessary to increase the pressure by the regulating member on the developer carrier. there were. However, when the contact pressure by the regulating member becomes high, the toner is likely to be fused on the regulating member, and there is a concern that the image quality may deteriorate due to the occurrence of white streaks or the like.

  On the other hand, in the regulating member using the two-end supported sheet-like elastic member (2), the nip width of the abutting portion is widened by using a soft elastic body for the sheet portion, and the abutting pressure is excessively high. Can be avoided. However, in the soft elastic body, there is a concern that the contact pressure distribution in the nip is uneven and the toner coating layer regulation and frictional charging become non-uniform.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a developing device capable of stable toner coat layer regulation and triboelectric charging while avoiding image quality degradation such as white streaks. To do.

In order to achieve the above object, the present invention provides:
In a developing device having a developer layer thickness regulating member that is provided so as to contact the surface of a rotatable developer carrier and regulates the layer thickness of the developer carried on the developer carrier.
The developer layer thickness regulating member is
A sheet-like elastic member that comes into contact with the surface of the developer carrier along the rotation axis direction of the developer carrier;
Two support members that are provided on the upstream side and the downstream side, respectively, in the rotation direction of the developer carrier with respect to the contact portion between the developer carrier and the sheet-like elastic member, and support the sheet-like elastic member When,
Have
When the developer layer thickness regulating member is in a state where the sheet-like elastic member is not in contact with the developer carrier, the sheet-like elastic member is supported by the two support members in a state where a tension is applied. It is characterized by being.

  According to the present invention, it is possible to provide a developing device capable of stable toner layer regulation and frictional charging while avoiding image quality degradation such as white streaks.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

[Embodiment 1]
FIG. 2 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus according to the first embodiment.

The image forming apparatus of the present embodiment is a full color laser printer using an electrophotographic process. The image forming apparatus according to the present embodiment includes an image forming apparatus main body A and a process cartridge B that is detachably attached to the image forming apparatus main body A. The process cartridge B includes a charging device, a developing device D, a cleaning device, a photosensitive drum 1 as an image carrier, and the like.

  The process cartridge B (By, Bm, Bc, Bk) is provided for each color of yellow, magenta, cyan, and black. These are arranged in quadruplicate, and a full color image is formed by transferring an image of the developer formed on the photosensitive drum 1 by each color process cartridge onto the intermediate transfer belt 20 of the transfer device. . Thereafter, an image is formed through a transfer process to a recording material and a fixing process.

  Here, in this embodiment, as the developer, non-magnetic one-component toner having an average particle diameter of 6.0 μm is used for each color. Details of the process cartridge will be described later.

  The toner images formed on the photosensitive drums 1 by the process cartridges of the respective colors are transferred to primary transfer rollers 22y, 22m, 22c, which are provided at positions facing the photosensitive drums 1 of the respective colors with the intermediate transfer belt 20 interposed therebetween. The image is transferred onto the intermediate transfer belt 20 by 22k. The toner images transferred onto the intermediate transfer belt 20 are collectively transferred onto the recording material by the secondary transfer roller 23 provided on the downstream side in the moving direction of the intermediate transfer belt 20. The untransferred toner on the intermediate transfer belt is collected by the intermediate transfer belt cleaner 21.

  The recording material P is stacked in a cassette 24 below the image forming apparatus main body A, and is conveyed by a feeding roller 25 together with a request for an image forming operation, and is transferred onto the intermediate transfer belt 20 at a transfer position by a secondary transfer roller 23. The toner image formed on is transferred.

  Thereafter, the toner image on the recording material is heated and fixed on the recording material by the fixing unit 26 and is discharged to the outside of the image forming apparatus main body A through the discharge unit 27.

  In the image forming apparatus according to the present embodiment, the upper unit that stores the process cartridges of the four colors and the lower unit that stores the transfer unit, the recording material, and the like are separable. As a result, when a jam such as a jam of a recording material occurs or when a process cartridge is replaced, the upper and lower units are separated, so that jam processing and cartridge replacement can be easily performed.

  Next, the configuration of the process cartridge B will be described.

  FIG. 3 is a cross-sectional view showing a schematic configuration of one process cartridge B among the four process cartridges By, Bm, Bc, Bk arranged in parallel in one direction. The configuration of the four process cartridges By, Bm, Bc, Bk is essentially the same.

  An organic photoreceptor in which an outer peripheral surface of an aluminum cylinder is coated with an undercoat layer, a carrier generation layer, and a carrier transfer layer, which are functional films, in this order on the photosensitive drum 1 that is the center of an image forming process (image forming operation). A drum is used. In the image forming process, the photosensitive drum 1 is driven in the direction of arrow a in FIG. 3 at a predetermined speed.

  The charging roller 2 as a charging device is driven to rotate in the direction of arrow b in FIG. 3 when a roller portion of conductive rubber is brought into pressure contact with the photosensitive drum 1. Here, a direct current voltage of −1100 V is applied to the cored bar of the charging roller 2 with respect to the photosensitive drum 1 as a charging step, and the surface potential of the photosensitive drum 1 is caused by the electric charge induced thereby. , A uniform dark portion potential (Vd) of −550 V is formed.

  The spot pattern of the laser light emitted by the scanner unit 10 corresponding to the image data on the uniform surface charge distribution surface exposes the photosensitive drum 1 as indicated by an arrow L in FIG. . The exposed portion of the photosensitive drum 1 loses its surface charge due to carriers from the carrier generation layer, and the potential decreases. As a result, an electrostatic latent image is formed on the photosensitive drum 1 with the light portion potential Vl = −100 V at the exposed portion and the dark portion potential Vd = −550 V at the unexposed portion.

  The electrostatic latent image formed on the photosensitive drum 1 is formed on a developing roller 3 as a rotatable developer carrying member, and is developed by the developing device D having a toner coat layer having a predetermined coat amount and a charge amount. Developed by action. The configuration of the developing device D will be described later.

  The developing roller 3 rotates in the forward direction (the direction of arrow c in FIG. 3) with respect to the rotation direction of the photosensitive drum 1 while being in contact with the photosensitive drum 1. A DC bias = −350 V is applied to the developing roller 3 during the image forming process. The toner charged negatively by the frictional charge on the developing roller 3 flies only to the bright portion potential portion due to the potential difference in the developing portion that contacts the photosensitive drum 1, thereby making the electrostatic latent image a real image. Is done.

  The intermediate transfer belt 20 in contact with the photosensitive drum 1 of each process cartridge B is pressed against the photosensitive drum 1 by primary transfer rollers 22y, 22m, 22c, and 22k that face the photosensitive drum 1. Further, a DC voltage is applied to the primary transfer rollers 22 y, 22 m, 22 c, and 22 k, and an electric field is formed between the photosensitive drum 1.

  As a result, the toner image formed on the photosensitive drum 1 is transferred from the photosensitive drum 1 to the intermediate transfer belt 20 under the force of the electric field in the pressure contact area.

  On the other hand, the untransferred toner remaining on the photosensitive drum 1 without being transferred to the intermediate transfer belt 20 is scraped off from the drum surface by the urethane rubber cleaning blade 6 installed in the cleaning device C, and the cleaning device C. Housed in (cleaning container).

  FIG. 4 is a schematic cross-sectional view of the developing device D.

  The developing device D includes a developing roller 3, a supply roller 5, a regulating member 4, a developer t, and a developing container that stores these. The regulating member 4 is a characteristic configuration of the present embodiment, and is configured such that the sheet-like elastic member is in contact with the surface of the developing roller 3 by being supported at both ends by the supporting member. This corresponds to a developer layer thickness regulating member that regulates the layer thickness of the developer carried thereon.

The developing roller 3 is a φ12 mm elastic roller in which a conductive elastic layer 3 mm is formed on a core metal having an outer diameter φ6 mm, and silicone rubber having a volume resistance of 10 ⁶ Ωm is used for the elastic layer. ing. The elastic roller surface layer may be provided with a coat layer having a function of imparting charge to the developer. In the present embodiment, the elastic layer has a hardness of 45 ° in accordance with JIS-A in order to stably and elastically contact the photosensitive drum 1, and the surface roughness Rz is 6 μm in order to obtain a predetermined toner coat amount. The developing roller 3 was used.

The supply roller 5 is an elastic sponge roller having an outer diameter of φ16 mm in which an elastic layer of insulating urethane sponge rubber having a volume resistance value of 10 ¹⁴ Ωcm is formed on a core bar having an outer diameter of φ8 mm.

  The developing roller 3 rotates in the forward direction (the direction indicated by the arrow c in FIG. 4) with respect to the rotation direction of the photosensitive drum 1 while being in contact with the photosensitive drum 1. Further, the supply roller 5 rotates in the direction opposite to the rotation direction of the developing roller 3 (the direction indicated by the arrow d in FIG. 4) while contacting the developing roller 3.

  The supply roller 5 has a function of attaching the developer t, which is a non-magnetic one-component toner in the developing container, transporting the developer t to a contact portion with the developing roller 3 and supplying the developer t to the developing roller 3. Further, the supply roller 5 has a function of removing the toner remaining on the developing roller 3 without being developed at the developing unit from the developing roller 3 and collecting it in the developing container.

  When the non-magnetic one-component toner supplied from the supply roller 5 onto the developing roller 3 passes through the contact surface between the developing roller 3 and the regulating member 4, it is charged by frictional charging, and the coating layer thickness is regulated. Upon receipt, a toner coat layer having a predetermined charge amount and a coat layer thickness is formed.

[Embodiment 2]
FIG. 5 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus according to the second embodiment. In addition, about the component similar to Embodiment 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The image forming apparatus according to the present embodiment is a monochrome laser printer using an electrophotographic process, and includes an image forming apparatus main body A and a process cartridge B that is detachable from the main body. The process cartridge B includes a charging device, a developing device D, a cleaning device, a photosensitive drum 1 as an image carrier, and the like.

  The toner image formed on the photosensitive drum 1 of the process cartridge B is transferred to the recording material and then fixed, thereby forming an image on the recording material. Here, a magnetic monocomponent toner having an average particle diameter of 6.0 μm is used as the developer. Details of the process cartridge will be described later.

  The recording material P is stacked in a cassette 24 below the image forming apparatus main body A, and is conveyed by a feeding roller 25 together with a request for an image forming operation, and a nip portion (transfer area) between the transfer roller 28 and the photosensitive drum 1. ), The toner image formed on the photosensitive drum 1 is transferred.

  Thereafter, the toner image on the recording material is heated and fixed on the recording material by the fixing unit 26, and is discharged to the outside of the image forming apparatus main body A through the discharge unit 27.

  Next, the configuration of the process cartridge B will be described.

  As the photosensitive drum 1 which is the center of the image forming process, an organic photosensitive drum is used in which an undercoat layer which is a functional film, a carrier generation layer, and a carrier transport layer are sequentially coated on the outer peripheral surface of an aluminum cylinder. . In the image forming process, the photosensitive drum 1 is driven in the direction of arrow a in FIG. 5 by the image forming apparatus at a predetermined speed.

  The charging roller 2 as the charging device is driven to rotate in the direction of arrow b in FIG. 5 when the roller portion of the conductive rubber is brought into pressure contact with the photosensitive drum 1. Here, a direct current voltage of −1100 V is applied to the cored bar of the charging roller 2 with respect to the photosensitive drum 1 as a charging step, and the surface potential of the photosensitive drum 1 is caused by the electric charge induced thereby. , A uniform dark portion potential (Vd) of −550 V is formed.

A spot pattern of laser light emitted by the scanner unit 10 corresponding to the image data on the uniform surface charge distribution surface exposes the photosensitive drum 1 as indicated by an arrow L in FIG. . The exposed portion of the photosensitive drum 1 loses its surface charge due to carriers from the carrier generation layer, and the potential decreases. As a result, an electrostatic latent image is formed on the photosensitive drum 1 with the light portion potential Vl = −100 V at the exposed portion and the dark portion potential Vd = −550 V at the unexposed portion.

  The electrostatic latent image formed on the photosensitive drum 1 is formed on the developing sleeve 8 as a rotatable developer carrying member, and is developed by the developing device D having a toner coat layer having a predetermined coat amount and a charge amount. Developed by action. The configuration of the developing device D will be described later.

  The developing sleeve 8 has a gap of 280 μm at the closest part between the developing sleeve 8 and the photosensitive drum 1, and rotates in the forward direction (the direction of arrow c in FIG. 5) with respect to the rotating direction of the photosensitive drum 1. . The developing sleeve 8 is applied with a rectangular wave of DC bias = −350 V and AC bias = 1400 Vpp of frequency f = 2200 Hz in the image forming process.

  The magnetic toner, which is negatively charged by frictional charging on the developing sleeve 8, reciprocates between the photosensitive drum 1 and the developing sleeve 8 at an adjacent developing portion by an AC bias applied to the developing sleeve. Then, the magnetic toner flies only to the bright portion potential portion due to the relationship between the potential of the electrostatic latent image formed on the photosensitive drum 1 and the potential due to the bias applied to the developing sleeve. The latent image is turned into a real image.

  The fixed magnet roller included in the developing sleeve is provided with a magnetic pole in the developing container and in the vicinity of the developing portion. In this embodiment, the magnetic force of the magnetic pole in the vicinity of the developing portion is set to 800 G on the surface of the developing sleeve. I have to. Thus, it is possible to prevent the toner having an inappropriate charge that cannot be controlled by the above-described potential setting from erroneously flying to the Vd portion.

  A DC voltage is applied to the transfer roller 28 that contacts the photosensitive drum 1, and an electric field is formed between the photosensitive drum 1 and the transfer roller 28. As a result, the toner image formed on the photosensitive drum 1 is applied to the recording material from the photosensitive drum 1 under the force of an electric field in the transfer region where the photosensitive drum 1 and the transfer roller 28 are in pressure contact. Transcribed.

  On the other hand, untransferred toner remaining on the photosensitive drum 1 without being transferred to the recording material is scraped off from the drum surface by a urethane rubber cleaning blade installed in the cleaning device C, and the cleaning device C (cleaning container C). ).

  FIG. 6 is a schematic cross-sectional view of the developing device D.

  The developing device D includes a developing sleeve 8 including a fixed magnet roller 7, a regulating member 4, a developer t, and a developing container for storing them. The regulating member 4 is a characteristic configuration of the present embodiment, and is configured so that the sheet-like elastic member is in contact with the surface of the developing sleeve 8 by being supported at both ends by the supporting member. This corresponds to a developer layer thickness regulating member that regulates the layer thickness of the developer carried thereon.

  The developing sleeve 8 is a φ12 mm metal sleeve coated with a conductive resin, and a fixed magnet roller 7 having a predetermined magnetic pole arrangement is provided inside the developing sleeve 8. The magnetic toner in the developing container is attracted to the surface of the developing sleeve 8 by the magnetic force of the magnet roller 7.

The magnetic toner adhering to the surface of the developing sleeve 8 is conveyed by the rotation of the developing sleeve 8 and is charged by frictional charging when passing through the contact surface between the developing sleeve 8 and the regulating member 4. Further, the magnetic toner is regulated by a coat layer thickness, and a toner coat layer having a predetermined charge amount and a coat layer thickness is formed.

  Hereinafter, an example in which the regulating member 4 configured by supporting the both ends of the sheet-like elastic member by the support member, which is a characteristic configuration of the present invention, is applied to the image forming apparatus of the above-described embodiment will be described. . In addition, the same code | symbol is attached | subjected about the component similar to embodiment mentioned above.

[Example 1]
FIG. 1 is a schematic cross-sectional view illustrating a regulating member 4 according to the first embodiment.

  In this example, as shown in FIG. 1, the image forming apparatus of Embodiment 1 uses a regulating member 4 in which a sheet-like elastic member 4a is supported at both ends by a supporting member 4b. Here, the supporting member 4b is provided on the upstream side and the downstream side in the rotation direction of the developing roller 3 with respect to the contact portion 9 between the developing roller 3 and the sheet-like elastic member 4a, and supports the sheet-like elastic member 4a. is doing. Further, the contact portion 9 is configured by the sheet-like elastic member 4 a contacting the surface of the developing roller 3 along the rotation axis direction of the developing roller 3.

  The sheet-like elastic member 4a is preferably made of rubber. In the present embodiment, the sheet-like elastic member 4a is made of sheet-like urethane rubber having a JIS-A hardness of 65 degrees and a thickness of 0.5 mm. Both ends of the sheet-like elastic member 4a along the rotation direction of the developing roller 3 are fixed to the outer wall of the support member 4b having a substantially U-shaped cross section by bonding.

  Then, in a state before the developing device D is assembled and before the regulating member 4 (sheet-like elastic member 4a) comes into contact with the developing roller 3, the sheet-like elastic member 4a has a cross-section in a state where tension is applied. It is supported between the two support portions of the substantially U-shaped support member 4b. The sheet-like elastic member 4a is brought into contact with the developing roller 3 in this state. Hereinafter, the distance between the regulating member 4 and the developing roller 3 at this time is referred to as an “entry (intrusion) amount”. Here, when the regulating member 4 is in a state in which the sheet-like elastic member 4a does not contact the developing roller 3 (a state in which the regulating member 4 alone (developer layer thickness regulating member alone)), the sheet-like elastic member 4a is in tension. Will be supported between the two support parts of the support member 4b in the state which has acted.

  In defining the tension, the tensile strain relative to the natural length is 30% between the support portions that support the sheet-like elastic member 4a (between both support portions of the support member 4b having a substantially U-shaped cross section).

  In this contact state, a drag force accompanying the contact between the sheet-like elastic member 4a and the developing roller 3 is appropriately generated, the pressure in the contact nip is not excessively increased, the nip width is widened, and the contact is made. Since the pressure distribution can be made uniform, stable toner coat layer regulation and triboelectric charging are possible.

  Here, FIG. 7 shows the result calculated by the finite element method for the contact pressure distribution between the present example and the comparative example.

  As a comparative example, a cantilever type plate shape restricting member and a double supported sheet shape restricting member were used. FIG. 10A shows a case where a cantilever type plate-like regulating member 104a is used, and FIG. 10B shows a case where a both-end supported sheet-like regulating member 104b is used.

  As can be seen from FIG. 7, in this embodiment, the nip width can be widened and the contact pressure distribution can be set uniformly. Even when the amount of entry is changed, the nip width is wide and the contact pressure distribution is uniform.

  On the other hand, in the cantilever type plate-shaped regulating member 104a, if the amount of entry is increased in order to maintain the nip width equal to that of the present embodiment, the maximum pressure in the nip becomes excessively large, and the toner fusion is performed. There is a concern that it will cause. Further, if the amount of entry is reduced in order to maintain the maximum pressure in the toner nip equal to that in the present embodiment, there is a concern that the nip width becomes narrow and toner charging failure is caused.

  In the double-sided sheet-like regulating member 104b, if the amount of entry is increased in order to maintain the nip width equal to that of the present embodiment, the contact pressure distribution becomes non-uniform and the toner coat layer becomes non-uniform. End up. If the contact pressure distribution is made uniform, sufficient pressure cannot be obtained, and the nip width becomes narrow.

  Next, in order to determine an appropriate value of the tensile strain with respect to the natural length in this example, the relationship between the tensile strain and the contact state was examined using a finite element method.

  FIG. 8 is a graph showing the contact pressure distribution when the strain of the sheet-like elastic member 4a is defined in the range of 10% to 30% in the configuration of the present embodiment.

  From this graph, there is a concern that the pressure becomes non-uniform when the strain is 15% or less. Therefore, it is desirable that the sheet-like elastic member 4a is in a state in which a tensile strain with respect to the natural length is 20% or more before the contact with the developing roller 3.

  As described above, in this embodiment, the pressure in the contact portion 9 is not excessively increased, the nip width can be widened, and the contact pressure distribution can be set uniformly. By not excessively increasing the pressure at the contact portion 9, it is possible to suppress the occurrence of toner fusion in the regulating member 4 (sheet-like elastic member 4 a), and to avoid deterioration in image quality such as white streaks. It becomes. In addition, since the width of the contact portion 9 is wide and the contact pressure distribution is uniform, it is possible to provide a developing device capable of stable toner layer regulation and frictional charging.

[Example 2]
FIG. 9 is a schematic view showing the regulating member 4 of the second embodiment, where FIG. 9A is a cross-sectional view and FIG. 9B is a perspective view.

  In this embodiment, a cylindrical elastic member 4d formed in a seamless cylindrical shape (endless shape) with respect to the sheet-like elastic member 4a of the first embodiment is used as the sheet-like elastic member.

  Further, in this embodiment, the support member that supports the cylindrical elastic member 4d is two circles that are arranged in parallel with the support member 4b of the first embodiment with a predetermined interval so as to sandwich the contact portion 9 therebetween. It is comprised by the columnar support member 4e. The two columnar support members 4e are disposed on the inner surface (inner peripheral side) of the cylindrical elastic member 4d and are held in a movable state by a holding member (not shown). By moving at least one of the two columnar support members 4e, the circumferential length of the cylindrical elastic member 4d can be changed (adjustable), thereby adjusting the tension acting on the cylindrical elastic member 4d. be able to.

  In a state before the developing device D is assembled and before the regulating member 4 (cylindrical elastic member 4d) comes into contact with the developing roller 3, the tension is applied to the cylindrical elastic member 4d. The interval between the two columnar support members 4e is adjusted and held by the holding member. The cylindrical elastic member 4d is brought into contact with the developing roller 3 in this state. At this time, the cylindrical elastic member 4d need not be bonded to the columnar support member 4e.

  Also in this embodiment, a drag force accompanying the contact between the cylindrical elastic member 4d and the developing roller 3 is appropriately generated, the pressure in the contact nip is not excessively increased, the nip width is widened, and the contact is made. Since the pressure distribution can be made uniform, stable toner coat layer regulation and triboelectric charging are possible.

  Furthermore, since there is no need to bond the cylindrical elastic member 4d to the columnar support member 4e, there is no concern about peeling and the stability against changes with time is also provided.

  In the present embodiment, in a state before the developing device D is assembled and before the regulating member 4 comes into contact with the developing roller 3, two circles are applied so that tension is applied to the cylindrical elastic member 4 d. Although the interval between the columnar support members 4e is adjusted, the present invention is not limited to this. By setting (deriving) an interval at which the tension acts on the cylindrical elastic member 4d in advance, after the regulating member 4 and the developing roller 3 are in contact with each other, two columnar supports are set at an interval set in advance. The member 4e may be disposed (moved). As described above, when the restricting member 4 is in a state in which the sheet-like elastic member 4a is not in contact with the developing roller 3 (state of the restricting member 4 alone), the sheet-like elastic member 4a is a cylinder in a state where tension is applied. What is necessary is just to be supported by the elastic member 4d.

  In this embodiment, two columnar support members 4e are used as support members for supporting the cylindrical elastic member 4d. However, the present invention is not limited to this. That is, a plurality of support members that support the cylindrical elastic member 4d are provided including two support members provided on the upstream side and the downstream side in the rotation direction of the developing roller 3 with respect to the contact portion 9. That's fine. And it is the structure which can adjust the tension | tensile_strength which acts on the cylindrical elastic member 4d by changing the perimeter of the cylindrical elastic member 4d by providing at least 1 among several support members so that a movement is possible. That's fine.

  In Examples 1 and 2 described above, the case where the regulating member 4 is applied to the image forming apparatus of the first embodiment has been described. However, the same can be applied to the image forming apparatus of the second embodiment.

FIG. 3 is a schematic cross-sectional view showing a restricting member of Example 1. FIG. 2 is a schematic cross-sectional view illustrating the image forming apparatus according to the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating the process cartridge according to the first embodiment. FIG. 2 is a schematic cross-sectional view illustrating the developing device according to the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating an image forming apparatus according to a second embodiment. FIG. 4 is a schematic cross-sectional view illustrating a developing device according to a second embodiment. The figure for comparing contact pressure distribution of Example 1 and a comparative example. The figure which shows the contact pressure distribution with respect to the tensile distortion of the sheet-like elastic member in Example 1. FIG. FIG. 6 is a schematic cross-sectional view showing a regulating member of Example 2. The schematic sectional drawing which shows the control member of a comparative example. FIG. 6 is a schematic diagram showing a case where a conventional cantilever blade-shaped developer regulating member is applied to a contact developing device using non-magnetic toner. FIG. 10 is a schematic view showing a case where a conventional cantilever blade-shaped developer regulating member is applied to a non-contact developing device using magnetic toner. Schematic which shows about the developing device using the developer control member by the conventional both-end-supported sheet-like elastic member.

Explanation of symbols

D developing device 3 developing roller 4 regulating member 4a sheet-like elastic member 4b supporting member 4d cylindrical elastic member 4e columnar supporting member 8 developing sleeve 9 contact portion

Claims (8)

In a developing device having a developer layer thickness regulating member that is provided so as to contact the surface of a rotatable developer carrier and regulates the layer thickness of the developer carried on the developer carrier.
The developer layer thickness regulating member is
A sheet-like elastic member that comes into contact with the surface of the developer carrier along the rotation axis direction of the developer carrier;
Two support members that are provided on the upstream side and the downstream side, respectively, in the rotation direction of the developer carrier with respect to the contact portion between the developer carrier and the sheet-like elastic member, and support the sheet-like elastic member When,
Have
When the developer layer thickness regulating member is in a state where the sheet-like elastic member is not in contact with the developer carrier, the sheet-like elastic member is supported by the two support members in a state where a tension is applied. A developing device.   In a state before the assembly of the developing device and before the sheet-like elastic member is brought into contact with the developer carrier, the developer layer thickness regulating member is in a state where tension is applied. The developing device according to claim 1, wherein a sheet-like elastic member is configured to be supported by the two support members. The sheet-like elastic member is provided endlessly,
3. The development according to claim 1, wherein the two support members support the sheet-like elastic member by being provided on an inner circumferential side of the sheet-like elastic member provided endlessly. apparatus. A plurality of support members including the two support members are provided on the inner peripheral side of the sheet-like elastic member provided endlessly,
A holding means for holding at least one of the plurality of support members so as to be movable is provided,
The developing device according to claim 3, wherein the peripheral length of the sheet-like elastic member is configured to be changeable by movement of a support member that is movably held by the holding unit.   The developing device according to claim 1, wherein the sheet-like elastic member is supported in a state where a tensile strain with respect to a natural length is 20% or more.   6. The developing device according to claim 5, wherein the sheet-like elastic member is supported in a state where a tensile strain with respect to a natural length is 30% or less.   The developing device according to claim 1, wherein the sheet-like elastic member is made of rubber.   An image forming apparatus comprising: an image carrier; and the developing device according to claim 1 that performs a developing action on the image carrier.

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