JP2019003018A - Image forming device - Google Patents

Abstract

To provide an image forming device provided with a drive transmission mechanism having a stable drive transmission performance.SOLUTION: An image forming device includes: a driving force transmission mechanism for transmitting a driving force from a power source inside a device main body to a rotation body; a first coupling member rotated by a driving force from a power source; a second coupling member connected to the rotation body; a dielectric sandwiched between the first coupling member and the second coupling member; a voltage application part for applying a voltage between each coupling member and the dielectric; the driving force transmission mechanism for generating an electrostatic adsorption force for regulating the relative movement of the first coupling member and the second coupling member via the dielectric body by the voltage application; a control part for controlling the driving force transmission mechanism; a state determination part for determining whether a transmission state of the driving force of the driving force transmission mechanism is a first state or a second state, and when determined to be in the second state, the control part is allowed to execute an avoidance operation for avoiding that the drive transmission mechanism continues to be in the second state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cartridge having a driving force transmission mechanism and an image forming apparatus using the same.

In a so-called process cartridge type electrophotographic image forming apparatus, a power transmission member connected to a drive source provided in the apparatus body and a photosensitive drum for supplying a rotational driving force to a rotating body such as a photosensitive drum provided in the process cartridge Etc. are coupled so that the driving force can be transmitted.
In Patent Document 1, a twisted concave portion is provided in a coupling provided in the apparatus main body, a convex portion twisted in a coupling provided in the photosensitive drum is provided, and the concave portion and the convex portion are fitted to drive the photosensitive drum. A possible configuration is disclosed. In Patent Document 2, a ground provided at the rotating portion of the end portion of the photosensitive drum is provided by providing a coupling provided in the main body of the image forming apparatus and a ground contact to be connected when the coupling of the photosensitive drum is fitted. A configuration to take is disclosed.

Japanese Patent No. 3,408,082 Japanese Patent No. 3839932

  Here, in the coupling configuration in which the above-described twisted concave / convex shape is fitted and driven and transmitted, it is necessary to provide a gap in the concave / convex fitting portion from the viewpoint of manufacturing errors. This clearance becomes a backlash component in the rotational direction, and the drive transmission performance of a driven part such as a drum may deteriorate.

  An object of the present invention is to provide a cartridge having a drive transmission mechanism and an image forming apparatus having stable drive transmission performance.

In order to achieve the above object, an image forming apparatus according to the present invention includes:
A device body with a power source;
A cartridge that is detachable from the apparatus main body, and includes a rotating body that rotates by a driving force transmitted from the power source;
A driving force transmission mechanism for transmitting a driving force from the power source to the rotating body,
A first coupling member that rotates with a driving force transmitted from the power source;
A second coupling member coupled to the rotating body;
A dielectric sandwiched between the first coupling member and the second coupling member;
A voltage applying unit for applying a voltage between the first coupling member, the dielectric, and the second coupling member;
With
By applying a voltage from the voltage application unit, an electrostatic attraction force that attracts the first coupling member and the second coupling member to each other via the dielectric is generated, and the rotation direction of the first coupling member A driving force transmission mechanism for restricting relative movement between the first coupling member and the second coupling member in
A control unit for controlling the driving force transmission mechanism;
The transmission state of the driving force of the driving force transmission mechanism is the first state where the electrostatic attraction force that restricts the relative movement is generated, or the electrostatic attraction force that restricts the relative movement occurs. A state determination unit for determining whether the second state is not,
An image forming apparatus comprising:
When the state determination unit determines that the state is the second state, the control unit causes the driving force transmission mechanism to perform an avoidance operation to avoid the second state from continuing.

  As described above, according to the present invention, by rotating and adsorbing the planes to each other, it is possible to achieve a rotational drive backlash without being affected by the resistance change of the drive transmission member due to energization deterioration or environmental change, It is possible to provide a cartridge including a drive transmission mechanism and an image forming apparatus having stable drive transmission performance.

Cross-sectional view of coupling, photosensitive drum, and driving device in this embodiment Sectional view of the main body and cartridge of the image forming apparatus in this embodiment Cross-sectional view of the cartridge in this embodiment The perspective view of the cleaner unit in a present Example In the present embodiment, a perspective view of the apparatus main body and the cartridge with the open / close door opened. Sectional view of coupling and drive device before engagement in the device body Sectional view of coupling and drive device before engagement in the device body Sectional view of coupled coupling, photosensitive drum, and drive unit Cross-sectional view of coupling and drive device before engagement in the device body Sectional view of coupled coupling, photosensitive drum, and drive unit The figure explaining the relationship between electrostatic attraction force and transmittable torque Equivalent circuit diagram of coupling configuration using electrostatic attraction force Diagram explaining the relationship between electrostatic attraction force, current, and voltage A diagram explaining the relationship between electrostatic attraction force, current, and volume resistivity Block diagram showing the configuration of control to which this configuration is applicable Control flowchart to which the present invention is applicable Relationship diagram of time and drive torque related to detection means to which this configuration can be applied Block diagram showing a configuration according to the second embodiment. Relationship diagram between measurement time and measurement pulse when drive transmission is normal according to embodiment 2 Relationship diagram between measurement time and measurement pulse when drive transmission is indefinite according to the second embodiment FIG. 7 is a diagram illustrating the relationship between the amplitude spectrum and the frequency after Fourier transform according to the second embodiment. FIG. 7 is a diagram illustrating the relationship between the amplitude of the rotation frequency of the member 43 and the applied bias according to the second embodiment. Control flowchart according to embodiment 3 Control flowchart according to embodiment 4

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail 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. That is, it is not intended to limit the scope of the present invention to the following embodiments.

Example 1
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the direction of the axis of rotation of the photosensitive drum is the longitudinal direction. In the longitudinal direction, the side on which the photosensitive drum receives driving force from the main body of the image forming apparatus is the driving side (the driven coupling 63 side in FIG. 1), and the opposite side is the non-driving side.
The overall configuration and the image forming process will be described with reference to FIGS.
FIG. 2 is a cross-sectional view of an image forming apparatus main body (hereinafter referred to as apparatus main body A) and a process cartridge (hereinafter referred to as cartridge B) of an electrophotographic image forming apparatus according to an embodiment of the present invention. .
FIG. 3 is a cross-sectional view of the cartridge B.
Here, the apparatus main body A of the electrophotographic image forming apparatus is an electrophotographic image forming apparatus portion excluding the cartridge B.

<Overall configuration of image forming apparatus>
In FIG. 2, an electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus) is a laser beam printer using an electrophotographic technique in which a cartridge B is detachable from an apparatus main body A. When the cartridge B is mounted on the apparatus main body A, the exposure device 3 (laser scanner unit) is disposed above the cartridge B. Further, a sheet tray 4 that accommodates a recording medium (hereinafter referred to as a sheet material P) that is an image forming target is disposed below the cartridge B. Further, the apparatus main body A includes a pickup roller 5a, a feeding roller pair 5b, a conveyance roller pair 5c, a transfer guide 6, a transfer roller 7, a conveyance guide 8, a fixing device 9, along the conveyance direction D of the sheet material P. A pair of discharge rollers 10, a discharge tray 11, and the like are sequentially arranged. The fixing device 9 includes a heating roller 9a and a pressure roller 9b.

<Configuration of the entire cartridge>
Next, the overall configuration of the cartridge B will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating the configuration of the cartridge B. The cartridge B is configured by combining the cleaning unit 60 and the developing device unit 20. The cleaning unit 60 includes a cleaning frame 71, a photosensitive drum 62, a charging roller 66, a cleaning blade 77, and the like.
On the other hand, the developing device unit 20 includes a bottom member 22, a developing container 23, a developing blade 42, a developing roller 32, a magnet roller 34, a conveying member 43, toner T, and the like. The cleaning unit 60 and the developing device unit 20 are coupled to each other so as to be rotatable.

<Configuration of cleaning unit>
Next, the configuration of the cleaning unit 60 will be described with reference to FIGS. 1 and 3 to 5. FIG. 1 is a cross-sectional view including the apparatus main body A in the vicinity of the drum unit 61. FIG. 4 is a perspective view illustrating the configuration of the cleaning unit 60. The cleaning blade 77 includes a support member 77a made of sheet metal and an elastic member 77b made of an elastic material such as urethane rubber. The cleaning blade 77 is fixed to the cleaning frame 71 by fixing both ends of the support member 77a with screws (not shown). It is arranged at a predetermined position. The elastic member 77 b comes into contact with the photosensitive drum 62 and removes residual toner from the outer peripheral surface of the photosensitive drum 62. The removed toner is stored in a waste toner chamber 71b (FIG. 3) of the cleaning unit 60.

As shown in FIG. 4, the urging member 74 and the charging roller bearing 66 c are attached to the cleaning frame 71. The shaft portion of the charging roller 66 is fitted into the charging roller bearing 66c. The charging roller 66 is urged against the photosensitive drum 62 by the urging member 74 and is rotatably supported by the charging roller bearing 66c. Then, driven rotation is performed as the photosensitive drum 62 rotates. Then, power is supplied to the charging roller 66 using an electrode plate (not shown) as a power supply path. As shown in FIG. 1, the photosensitive drum 62 is integrally coupled with a drum flange function part 63f and a flange 64, which are integrally formed with the driven coupling, respectively, and an electrophotographic photosensitive drum unit (hereinafter referred to as a drum unit 61). To be described). This bonding method uses caulking, adhesion, welding, or the like. The flange function portion 63f and the flange 64 have conductivity, and the drum shaft 78, which is also the first electrode having conductivity, is electrically connected to the ground electrode of the apparatus main body A. Further, the flange function portion 63f has a driving force receiving portion 63a that receives a driving force from the apparatus main body A. The drum unit 61 is rotatably supported by the cleaning frame 71.

  As shown in FIG. 5, when the cleaning unit is attached to the apparatus main body A, the positioning unit 80 is formed of a concentric circle with the drum shaft in order to accurately position the apparatus on the apparatus main body. Are formed at both longitudinal ends. With this configuration, the process cartridge B including the developing unit coupled to the cleaning unit is accurately positioned on the apparatus main body A.

<Removal of cartridge>
Next, attachment / detachment of the cartridge B with respect to the apparatus main body A will be described with reference to FIG.
FIG. 5 is a perspective view of the apparatus main body A and the cartridge B with the open / close door 13 opened in order to attach and detach the cartridge B. FIG.

An opening / closing door 13 is rotatably attached to the apparatus main body A. When the open / close door 13 is opened, the drive coupling provided in the apparatus main body A is moved in the longitudinal retracting direction of the process cartridge B by a mechanism (not shown). The apparatus body A is provided with a guide rail 12, and the cartridge B is mounted in the apparatus body A along the guide rail 12.
At this time, the cartridge B is positioned on the apparatus main body A by the positioning portion 80 and the rotation stopper 81 provided in the cleaning unit engaging with a positioning portion (not shown) of the apparatus main body A.

When the door 13 is closed, the drive coupling 90 moves in a direction approaching the driven coupling 63 provided in the process cartridge B, and the drive transmission surfaces of the coupling are joined. .
As shown in FIG. 1, the drive coupling 90 driven by the motor 95 of the apparatus main body A is a driven coupling 63 (shown in FIG. 1) provided in the cartridge B by the controller (control unit) of the apparatus main body as necessary. 6) and the electrostatic force described later. As a result, the photosensitive drum 62 coupled to the driven coupling 63a is rotated by receiving a driving force from the apparatus main body A.

<Image formation process>
Next, an outline of the image forming process will be described with reference to FIG. Based on the print start signal, the photosensitive drum 62, which is one of the rotating members and carries the developer image transferred to the recording material, is driven to rotate in the direction of arrow R at a predetermined peripheral speed (process speed). Is done. The charging roller 66 to which the bias voltage is applied contacts the outer peripheral surface of the photosensitive drum 62 and uniformly charges the outer peripheral surface of the photosensitive drum 62. The exposure device 3 outputs a laser beam L corresponding to the image information. The laser beam L passes through the exposure window 74 on the upper surface of the cartridge B and scans and exposes the outer peripheral surface of the photosensitive drum 62. As a result, an electrostatic latent image corresponding to the image information is formed on the outer peripheral surface of the drum 62.

  On the other hand, as shown in FIG. 3, in the developing device unit 20 as a developing device, the toner T in the toner chamber (toner storage chamber) 29 is agitated and conveyed by the rotation of the conveying member 43 and sent to the toner supply chamber 28. It is. The toner T is carried on the surface of the developing roller 32 by the magnetic force of the magnet roller 34 (fixed magnet). The layer thickness of the circumferential surface of the developing roller 32 is regulated while the toner T is frictionally charged by the developing blade 42. The toner T is transferred to the photosensitive drum 62 in accordance with the electrostatic latent image, and is visualized as a toner image.

Further, as shown in FIG. 2, the sheet material P stored in the lower part of the apparatus main body A is moved to the sheet tray by the pickup roller 5a, the feeding roller pair 5b, and the conveying roller pair 5c in accordance with the output timing of the laser beam L. 4 is fed. Then, the sheet material P is supplied to the transfer position between the photosensitive drum 62 and the transfer roller 7 via the transfer guide 6. At this transfer position, the toner image is sequentially transferred from the photosensitive drum 62 to the sheet material P. The sheet material P to which the toner image has been transferred is separated from the photosensitive drum 62 and is conveyed along the conveyance guide 8 to the fixing device 9.

  The sheet material P passes through the nip portion between the heating roller 9a and the pressure roller 9b constituting the fixing device 9. A pressure / heat fixing process is performed in the nip portion, and the toner image is fixed on the sheet material P. The sheet material P that has undergone the toner image fixing process is conveyed to the discharge roller pair 10 and discharged to the discharge tray 11.

  On the other hand, as shown in FIG. 3, the transferred photosensitive drum 62 is used again in the image forming process after the residual toner on the outer peripheral surface is removed by the cleaning blade 77. The toner removed from the photosensitive drum 62 is stored in a waste toner chamber 71 b of the cleaning unit 60. In the above, the charging roller 66, the developing roller 32, and the cleaning blade 77 are process means that act on the photosensitive drum 62.

<Drive transmission coupling>
Next, the configuration of the drive transmission coupling that forms the basis of the present invention will be described in detail with reference to FIGS. 1 and 6. The drive transmission coupling according to the present invention includes a drive coupling 90 provided in the apparatus main body A and a driven coupling 63 provided in the cartridge B. By making the coupling surfaces of the drive coupling 90 and the driven coupling 63 flat with each other, a backlash component of drive transmission due to the conventional uneven shape is not generated.
Hereinafter, the configuration of the driven coupling 63 provided in the cartridge B will be described.

  As shown in FIGS. 1 and 6, a driven coupling 63 as a coupling means is provided at one end in the longitudinal direction of the photosensitive drum 62 attached to the cartridge B. The driven coupling 63 has a coupling substrate 63a. The drum coupling base 63a is integrally provided with a drive transmission function part 63b having a diameter of 16 mm and a drum flange function part 63f. The distal end surface of the drive transmission function part 63b is a drive transmission surface 63c, which is a second electrode as a drive transmission function part that comes into contact with the drive-side coupling 90 provided in the apparatus main body A in a surface configuration. Are provided in a direction perpendicular to the rotational axis of the photosensitive drum 62. Here, the surface roughness (centerline average roughness) of the drive transmission surface 63c was set to Ra = 0.2 μm. Note that the surface roughness Ra of the coupling member and the dielectric described later is, for example, based on JIS surface roughness “JIS B 0601 (2001)”, and the center line average roughness measured using a surface roughness measuring instrument. Can be defined by Here, the surface roughness can be appropriately selected as long as Ra = 0.2 μm or less.

  When the surface roughness exceeds 0.2, the electrostatic attraction force decreases. A circular boss 63d having a diameter of 4 mm that defines the rotation center is formed by fitting one end of the drive transmission surface 63c on the rotational axis of the photosensitive drum 62 with the drive coupling 90. Here, the circular boss 63 d is a separate member from the driven coupling 63, and the other end is fitted in the hole 63 h of the driven coupling 63. The hole 63h is provided with a hole having a diameter of 4 mm on the rotational axis of the photosensitive drum 62 of the drive transmission surface 63c (electrostatic attracting portion 63g) and the driven coupling base 63a. Further, a 2 mm C chamfer is provided around the entrance, and a circular boss 62d, which is a separate member, is engaged with the hole. The engagement portion between the hole and the circular boss 63d is firmly fixed with an epoxy adhesive. Here, the method for fixing the circular boss 63d to the coupling base 63a is not limited to an adhesive such as epoxy, and can be selected as appropriate, such as screw-in type or press fitting by knurling.

  The drum flange function part 63 f is provided with a fitting part 63 f 1 in the direction opposite to the drive transmission function part 63 b in the axial direction of the photosensitive drum 62. When the drum flange function unit 63f is attached to the photosensitive drum 62, the fitting unit 63f1 fits the inner surface of the photosensitive drum 62 and caulks to fix the drum flange function unit 63f and the photosensitive drum 62. Here, the fixing method of the drum flange function part 63f is not limited to caulking, and can be appropriately selected such as adhesion.

Next, the material of each component will be described. The coupling base 63a is made of conductive aluminum. However, the material of the coupling base 63a is not limited to aluminum. In other words, metals such as iron and copper, conductive ceramics, and conductive resins commonly used in process cartridges, specifically polyacetal, polyester, epoxy resins, etc. with the aforementioned conductive agent added. The molded product used may be used. As a standard, the volume resistance is 1 × 10 ¹⁰ Ωcm or less.
By selecting the above configuration and materials, the driven coupling 63 is electrically connected to the photosensitive drum 62.
Further, as described in the description of the configuration of the cleaning unit 60, the drum 62 is electrically connected to the ground electrode 99 of the apparatus main body A via the leaf spring 64 and the drum shaft 78. Therefore, the driven coupling 63 is electrically connected to the ground of the apparatus main body A when the cartridge B is attached to the apparatus main body A, and is located on the ground side with respect to the drive coupling 90.

Further, the flange 64 described in the description of the configuration of the cleaning unit described above is conductive, and the drum shaft 78 having the same conductivity is electrically connected to the ground of the apparatus main body A. With the above configuration, the driven coupling 63 is electrically connected to the ground of the apparatus main body A via the drum shaft 78 when the cartridge B is mounted on the apparatus main body A.
The material of the circular boss 63d is made of polyacetal, which is an insulating member, in an electrically insulating relationship with the drive side coupling, and is separated from the conductive coupling base 63a in an electrically insulated state. It is configured. Here, the material of the circular boss may be appropriately selected as long as it can maintain an electrical insulating relationship with the coupling base 63a, and ceramic, polyester, epoxy resin, or the like can be selected as appropriate. As a standard of insulation, the volume resistance is 1 × 10 ¹⁵ Ωcm or more.

Next, the configuration of the drive coupling 90 provided in the apparatus main body A will be described.
The drive coupling 90 shown in FIG. 1 has a coupling base material 90a and is composed of an electrostatic adsorption function unit 90g.
The configuration of the drive transmission function unit 90b is a cylindrical shape with a diameter of 16 mm. When the cartridge B is mounted on the apparatus main body A, the driving transmission function unit 90b has a relative surface 90f that is opposed to the driven coupling 63 provided in the cartridge B in a surface configuration. It is provided in a direction orthogonal to 90 rotation axes. Furthermore, the rotation center portion of the relative surface of the coupling substrate 90 is fitted with a circular boss of the driven coupling 63, and has a depth of Φ4 at which the electrostatic adsorption function portion 90g and the drive transmission surface 63b come into contact with each other. The fitting hole 90d is provided. Further, a chamfer 90e of 2 mm is given around the entrance of the Φ4 hole.

The configuration of the electrostatic adsorption function part 90g as the third electrode is composed of a circular sheet member having a surface roughness Ra = 0.2 μm, a thickness of 120 μm, and a hole of Φ4 in the center and an outer diameter of Φ20 mm. ing. Here, the thickness of the electrostatic attraction function unit 90g is not particularly limited, and may be appropriately selected according to an electrostatic attraction force and required power described later. The surface roughness can be appropriately selected as long as Ra = 0.2 μm or less. Here, the reason why the surface roughness is set to R = a0.2 or less is that when the surface roughness exceeds Ra = 0.2, the electrostatic attraction force decreases. And this electrostatic adsorption function part 90g uses the conductive double-sided tape opened centering on the hole of diameter 8mm same as the diameter of C chamfering provided in the circumference | surroundings of the above-mentioned fitting hole 63d, and each provided Φ4 The holes are aligned and fixed to the coupling substrate in a penetrating state. Here, the hole provided in the conductive double-sided tape only needs to have a size equal to or larger than the diameter of the C chamfer provided around the fitting hole, and can be appropriately selected according to the required adhesive strength. Thus, the electrostatic attraction function unit 90g functions as the drive transmission surface 90c of the drive transmission function unit 63b that contacts the drive transmission surface 63c that is the drive transmission function unit of the driven coupling 63.

Next, the material of each component will be described.
As the material of the coupling substrate, aluminum having conductivity was used. The material of the coupling substrate is not limited to aluminum. In other words, metals such as iron and copper, conductive ceramics, and conductive resins commonly used in process cartridges, specifically polyacetal, polyester, epoxy resins, etc. with the aforementioned conductive agent added. The molded product used may be used. As a standard, the volume resistance is 1 × 10 ¹⁰ Ωcm or less.

Next, as the material of the electrostatic adsorption function unit 90g, a modified polyimide having a volume resistance of 1 × 10 ¹² Ωcm that functions as a dielectric was used. Here, the electrostatic attraction function unit 90g may be appropriately selected according to the electrostatic attraction force that will be described later, with a volume resistance in the range of 1 × 10 ¹⁰ Ωcm to 1 × 10 ¹⁴ Ωcm. The material is not particularly limited, such as polyacetal, polyvinylidene fluoride, urethane rubber, and the conductive agent for adjusting the volume resistance can be appropriately selected from an electronic conductive agent, an ionic conductive agent, and the like. . Examples of the electronic conductive agent include carbon black and graphite exhibiting electronic conductivity, oxides such as tin oxide, metals such as copper and silver, and conductive particles provided with conductivity by coating the surface of the particles with oxides or metals. Can be mentioned.

  Examples of the ionic conductive agent include ionic conductive agents having ion exchange properties such as quaternary ammonium salts and sulfonates exhibiting ionic conductivity. The dielectric as defined in the present invention is a substance that hardly conducts current and generates dielectric polarization when an electric field is applied, and has a resistance component and a dielectric component in a conductive mechanism such as an insulator containing conductive particles. This also includes substances with Here, the volume resistance of the electrostatic adsorption function unit 90g (sheet member) was measured at an applied voltage of 1000 V using Mitsubishi Chemical Analyc Hiresta UP MCP-HT450 type and a ring probe: UR.

Next, the conductive double-sided tape No. 5805 manufactured by Hitachi Maxell Co., Ltd. was used as the conductive double-sided tape used for fixing the coupling substrate 90a and the electrostatic adsorption function unit 90g. Here, the coupling method of the coupling substrate and the dielectric is not limited to the conductive double-sided tape, but can be appropriately selected from the configuration using the conductive adhesive.

  On the other hand, the drive coupling 90 is coupled to the large gear 97 that transmits the driving force of the motor 95 to the photoconductor ram 62 with the same rotating shaft. The large gear 97 is a helical gear, and this helical gear meshes with a small helical gear 96 fixed to or integrally with the shaft of the motor 95. Here, the helical direction of the helical gear of the gear is set to a direction in which the large gear 97 exerts a thrust force on the cartridge B side when the small gear 96 drives the large gear 97.

As the material of the large gear 97, a sliding grade polyacetal used in an image forming apparatus was used. Here, the material of the large gear needs to be electrically insulated from the drive coupling 90 described above. Accordingly, the material of the large gear is not limited to the sliding grade polyacetal, and can be appropriately selected as long as the material has a volume resistance of 1 × 10 ¹⁵ Ωcm or more. The material of the small gear 96 is also a sliding grade polyacetal used in the image forming apparatus. About this material, it can select suitably based on performance, such as a required life, without the restriction | limiting of volume resistance.

Alternatively, a material having the same conductivity as that of the drive coupling 90 may be selected as the material of the large gear 97, and the large gear 97 and the drive coupling 90 may be integrally formed. In this case, a material of 1 × 10 ¹⁵ Ωcm or more is selected using the small gear 96 as a measure of volume resistance, and the upstream side of the drive is insulated from the small gear 96. That is, any component interposed between the drive coupling 90 and the drive motor 95 may be insulated by selecting a material having a volume resistance of 1 × 10 ¹⁵ Ωcm or more.

Next, the coupling configuration of the drive coupling 90 and the large gear 97 will be described.
The coupling between the drive coupling 90 and the large gear 97 has a press-fitting configuration in which a knurl is cut at a fitting portion of the drive coupling 90. Here, the coupling configuration of the drive coupling 90 and the large gear 97 is not limited to the above-described press-fit configuration, and can be appropriately selected such as a configuration by bonding or insert molding while satisfying a necessary drive transmission torque. is there.
The drive coupling 90 abuts a power supply contact 98 provided on the apparatus main body at the end of the drive coupling 90 in the rotation axis direction opposite to the cartridge B. The power supply contact 98 is electrically connected to a high voltage power source (not shown) provided in the apparatus main body A. With this configuration, the high-voltage power supply and the drive coupling 90 are electrically connected. Then, power supply on / off to the drive coupling 90 is controlled by the controller 100 as a control unit provided in the apparatus main body A.

Next, the coupling action of the drive transmission coupling accompanying the mounting of the cartridge B to the apparatus main body A will be described.
With the configuration described above, when the opening / closing door of the apparatus main body A is opened, the drive coupling 90 provided in the apparatus main body A moves in a direction away from the cartridge B in the rotation axis direction.
Next, the cartridge B is mounted on the apparatus main body A. Then, by closing the open / close door, the drive coupling 90 that has been moved to the retracted position is moved to the cartridge B side. By this movement, the circular boss provided in the driven coupling 63 and the hole provided in the drive coupling 90 are engaged, and the rotation center of the drive coupling 90 is determined. Furthermore, the drive transmission surface as a drive transmission function part of the drive coupling 90 and the driven coupling 63 contacts. That is, the driving coupling 90 and the driven coupling 63 are joined in conjunction with opening and closing of the door.

Next, the operation of driving the photosensitive drum by the drive transmission coupling will be described.
First, the drive transmission mechanism on the drive transmission surface will be described with reference to FIGS. In the present invention, the electrostatic adsorption action by the Johnsen-Rahbek force is used as means for obtaining the friction on the drive transmission surface. The Johnsen-Rahbek force means that the volume resistivity of the dielectric (electrostatic adsorption function part 90b) is reduced to facilitate the movement of charges in the dielectric, and the outermost surface of the dielectric layer (drive transmission surface) that is the adsorption interface. 90c) is a force generated when a large amount of charge is induced. Generally, a large force is generated as compared with a case where the dielectric (electrostatic adsorption function part 90g) is an insulator having a very large resistance component (= coulomb force). That is, the electric charge applied to the electrode (power supply contact 98) moves to the outermost surface of the dielectric layer (drive transmission surface 90c) through the dielectric layer (electrostatic adsorption function part 90g). A part of the charge that has moved to the outermost surface of the dielectric layer (drive transmission surface 90c) flows to the substrate to be attracted (drive transmission surface 63c). It is charged by electric induction or dielectric polarization and generates an electrostatic attraction force.

Here, it can be seen from the above that the electrostatic attraction force is proportional to the width of the region in which current flows between the electrodes and the applied voltage.
Therefore, the first electrode (drum shaft 78) serving as a ground path has a function as a ground as long as a region to be energized is secured even at one point. On the other hand, it can be seen that the second electrode (drive transmission surface 63c) and the third electrode (electrostatic adsorption function part 90g) are different in that the attractive force is exerted according to the energized area. Therefore, the second electrode and the third electrode need a contact area corresponding to the required electrostatic attraction force, and as one of means for ensuring the contact area more effectively, the surface roughness of the electrode There is. For this reason, in the present invention, the surface roughness of the electrode surface that generates the electrostatic adsorption force is set to Ra = 0.2 or less. As a result, the contact area for energizing the second and third electrodes can be made smaller than when the surface roughness is larger than Ra = 0.2.

Next, the drive transmission action of the coupling accompanying the printing operation will be described.
As described above in connection with the mounting and dismounting of the cartridge (CRG), the drive transmission surface of the coupling is in a joined state as the cartridge is mounted on the image forming apparatus main body. Then, in accordance with the print signal, a voltage of −1 kV is applied via the power supply contact 98 by the controller provided in the apparatus main body A.

Thus, the coupling substrate 90a⇒the electrostatic adsorption function portion 90g as a dielectric layer⇒the drive transmission surface 9c⇒the drive transmission surface 63c⇒the coupling substrate 63a⇒the conductive portion on the inner surface of the photosensitive drum 62⇒the flange 64⇒the drum shaft 78 ⇒ Current flows to ground via ground contact 98.
At this time, when compared with the generation mechanism of the above-mentioned Johnsen-Rahbek force, the charge applied to the coupling base 63c as the electrode passes through the electrostatic adsorption function part 90g as the dielectric layer. And it moves to the drive transmission surface 90c which is the surface of the electrostatic adsorption function part 90g as a dielectric layer outermost surface. In response to this charge, the drive transmission surface 90c of the drive coupling as the object to be attracted is charged by electrostatic induction or dielectric polarization. As a result, an electrostatic attraction force is generated between the drive transmission surface 90c and the drive transmission surface 63c. Then, the motor 95 provided in the apparatus main body A is driven, and the large gear 97 is driven via the small gear 96. Along with this operation, the electrostatic attraction force is converted into a friction force between the drive transmission surface 90c and the drive transmission surface 63c, thereby driving the photosensitive drum 62.

  More specifically, the configuration of the present embodiment can be described as the configuration for generating an electrostatic attraction force between a pair of opposing electrodes facing each other with a dielectric interposed therebetween. That is, in the drive coupling 90 as the first coupling member, the joint portion (the relative surface 90f and the vicinity thereof) with the electrostatic attraction function portion 90g as the dielectric is connected to one of the counter electrodes. Correspond. Further, in the driven coupling 63 as the second coupling member, the joint portion (the drive transmission surface 63c and the vicinity region thereof) with the electrostatic attraction function portion 90g corresponds to the other electrode of the counter electrodes. . When a voltage is applied between the drive coupling 90, the electrostatic adsorption function unit 90g, and the driven coupling 63 by the high-voltage power supply 94, a negative charge is induced on the drive transmission surface 90c of the electrostatic adsorption function unit 90g. The Accordingly, a positive charge is induced in the drive transmission portion 63c of the opposite driven coupling 63. By forming such a charge arrangement, an electrostatic adsorption force is generated between the drive coupling 90 and the electrostatic adsorption function unit 90g, and between the electrostatic adsorption function unit 90g and the driven coupling 63. Then, they are in a state of being adsorbed to each other. The electrostatic attraction force is strong enough to transmit the rotational driving force transmitted from the motor 95 as the power source to the driving coupling 90 to the driven coupling 63 through the electrostatic attraction function unit 90g without loss. Thus, the voltage applied by the high voltage power supply 94 is adjusted. In the present embodiment, the configuration relating to the voltage application for generating the electrostatic attraction force such as the high voltage power supply 94, the controller (control unit) 100, the power supply contact 98, the ground contact 99, etc. is the voltage application unit in the present invention. Correspond.

<Transmissible torque and electrostatic attraction force>
Here, based on the coupling configuration shown in FIG. 11A, the relationship between the transmittable torque and the electrostatic attraction force in the driving force transmission mechanism using the electrostatic attraction force will be described. FIG. 11 (a)
The coupling configuration shown in FIG. 6 is a simplified configuration in which the centering mechanism using the circular boss is eliminated from the coupling configuration of the present embodiment. Specifically, the end surface of the drive transmission function portion 90b of the drive coupling 90 and the end surface of the drive transmission function portion 63b of the driven coupling 63 opposed thereto are respectively circular end surfaces from which fitting holes are removed. It has become. Further, the electrostatic attraction function part 63g has a through-hole for inserting the circular boss of this embodiment removed, and is adhered and fixed to the driven coupling 63 and is the same as the drive transmission function parts 90b and 63b. It is formed in the diameter. That is, the front end surface of the drive transmission function unit 90b of the drive coupling 90 is a drive transmission surface, and the driving force is transmitted by electrostatically adsorbing the drive transmission surface and the electrostatic adsorption function unit 63g. It has a configuration.

FIG. 11B is a graph showing the relationship between the electrostatic attraction force and the transmittable torque. The electrostatic attraction force and the transmittable torque are expressed by the following equations.

In the formula (1), T: transmittable torque [N · m], μ: coefficient of friction between the electrostatic adsorption function part 63g and the drive coupling 90, D: outer diameter [m] of the electrostatic adsorption function part 63g, p (R): electrostatic attraction force [Pa], r: radial position [m] from the center of rotation.
When the electrostatic attraction force is constant in the drive transmission surface, the expression (1) is expressed as follows.

Expression (2) is shown in the figure as shown in FIG. FIG. 11B shows the calculation result when the outer diameter D is 16 mm and the friction coefficient μ is 0.3. From this figure, it can be seen that the transmittable torque increases in proportion to the electrostatic attraction force. For example, when it is desired to set the transmittable torque to 0.1 Nm, it is sufficient that approximately 300 kPa is obtained as the electrostatic attractive force.

The electrostatic attraction force will be described with reference to FIGS.
FIG. 12 is an equivalent circuit showing the micro contact state of the drive transmission function unit 90b of the drive coupling 90 and the electrostatic adsorption function unit 63g and the electrical properties in the coupling configuration shown in FIG. FIG. In this figure, the electrostatic attraction force after a sufficient time has elapsed after voltage application is expressed by the following equation.

In Expression (3), ε0: dielectric constant in the atmosphere, Rg: contact resistance [Ω] between the electrostatic adsorption function unit 63g and the drive transmission function unit 90b, Rb: volume resistance [Ω] of the electrostatic adsorption function unit 63g is there. Further, V is an applied voltage, and d is an average gap distance [m] between the drive transmission function unit 90b and the electrostatic adsorption function unit 63g. Expression (3) indicates that the electrostatic adsorption force changes due to the volume resistance Rb of the electrostatic adsorption function unit 63g. To increase the electrostatic adsorption force, the volume resistivity of the electrostatic adsorption function unit 63g It can be seen that it is only necessary to reduce.

<Volume resistivity and electrostatic attraction force>
FIG. 13 shows the results of measuring the electrostatic attraction force and the current flowing at that time. The electrostatic adsorption force is measured by taking out the cartridge B equipped with the electrostatic adsorption function part 63g from the apparatus main body A and bringing the electrostatic adsorption function part 63g into close contact with the aluminum plate as if the drive coupling 90 was used. This was done by measuring the force to peel off the functional part 63g from the aluminum plate. In this preliminary test, the volume resistivity of the electrostatic adsorption function part 63g was 1 × 10 ¹¹ Ωcm and 1 × 10 ¹³ Ωcm, and the thickness was 75 μm. Here, the volume resistivity is obtained from the current value when the applied voltage is 100 V, and in general for medium resistance materials, the volume resistivity depends on the applied voltage depending on the temperature characteristics of the material and the non-ohmic conduction mechanism. Will change.

From the measurement result of the electrostatic adsorption force in FIG. 13A, it can be seen that the smaller the volume resistivity, the larger the electrostatic adsorption force. This is as described in the equation (3). Thus, the electrostatic adsorption force obtained in a so-called medium resistance region having a volume resistivity of about 1 × 10 ⁹ Ωcm to 1 × 10 ¹⁴ Ωcm is called a Johnsen-Rahbek force. While the Johnsen-Rahbek force can provide a large force, a leak current is generated, so it is necessary to pay attention to power consumption. Actually, when the current measurement result of FIG. 13B is seen, when the applied voltage is 400 V when the volume resistivity is 1 × 10 ¹¹ Ωcm, a current of about 400 μA is generated, and the power consumption is 400 V × 400 μA = 0.16 W. It becomes.

  On the other hand, it was found from the test results that if the volume resistivity is too small, the electrostatic attractive force is decreased. FIG. 14 shows the relationship between the volume resistivity and the measurement result of the electrostatic attraction force and the current flowing at that time, and the same test as the preliminary test described with reference to FIG. 13 was applied. This is a result obtained by setting the voltage to 200V. Referring to FIG. 12, if the volume resistivity is large, current does not flow, so the amount of charge accumulated in the gap is small. Therefore, the electrostatic attraction force that depends on the charge is reduced. That is, the Johnsen Rabeck force does not work. On the other hand, when the volume resistivity is small, more conductive carbon is deposited on the surface and the contact resistance Rg is small. As can be seen from the equation (3), when Rg becomes smaller than the volume resistance Rb, the voltage Vg applied to the gap becomes smaller. As a result, the electrostatic attraction force decreases. In other words, if the volume resistivity of the electrostatic adsorption function unit 63g is reduced, the electrostatic adsorption force necessarily increases, but this is not necessarily the case, and there is a volume resistivity that maximizes the electrostatic adsorption force. I understand.

In the present embodiment, a centering configuration (alignment function part that defines the rotation center) for aligning the respective rotation center axes of the drive coupling 90 and the driven coupling 63 using the circular boss 63d is provided near the rotation center axis. It arrange | positions in the area | region, ie, the center part in a circular adsorption | suction joint surface. The transmission of the rotational driving force without loss on the circular joint surface perpendicular to the rotation axis means that the joint surfaces do not deviate from each other in the circumferential direction, that is, the driving coupling 90 and the driven coupling 63 in the rotational direction. Relative movement between the two is restricted. What is important in suppressing the circumferential displacement of the joint surface is the adsorption force in the outer peripheral region away from the rotational axis center where the joint area is relatively wide. As shown in Expression (1), the transmittable torque T is determined by the integration of the product of the radial position r and the electrostatic attraction force P (r) at that position. That is, the electrostatic attraction force on the outer side in the radial direction (r is larger) contributes more to the transmittable torque than the inner side in the radial direction (r is smaller) of the electrostatic attraction function unit. Therefore, if a sufficient attracting force can be ensured in the outer peripheral region, the rotational driving force can be transmitted without loss even if the attracting force is not applied in the region near the center of the rotation axis. In the present embodiment, the electrostatic adsorption bonding surface of the driving coupling 90, the driven coupling 63, and the electrostatic adsorption function unit 90g is an annular surface having an inner diameter and an outer diameter, and the rotation center portion inside the bonding surface The centering configuration is arranged in Furthermore, the circular boss 63d, which is a centering member, is formed of an insulating member, and chamfering is applied to the opening of the fitting hole of each coupling. Furthermore, the inner diameter and the outer diameter of the electrostatic adsorption function unit 90g are expanded to the inner diameter side and the outer diameter side with respect to the bonding area (bonding surface) with each coupling. That is, in the electrostatic attraction function unit 90g, the outer diameter of the surface facing each coupling is larger than the outer diameter of the joining region (joining surface) with each coupling, and the inner diameter of the facing surface with each coupling is The inner diameter of the joining region (joining surface) with each coupling is smaller. Further, in the electrostatic attraction function portion 90g, the inner diameter of the through hole is set to be substantially the same as the outer diameter of the circular boss 63 so as to come into contact with the circular boss 63 on the inner diameter side of the annular joint surface. As a result, it is possible to reliably align the drive coupling 90 and the driven coupling 63 and to generate a stable electrostatic attracting force without leakage, thereby realizing a driving force transmission without loss.

  Actually, by applying a voltage of −1 kV, a current of about 170 μA flowed, and a drive transmission torque of about 1 kgfcm was obtained. Here, in the driving coupling base material 90a and the driven coupling base material 63a, an electrostatic attraction function portion 90g having a 2 mm C chamfering and an inner diameter of the same size as the circular boss 63d is formed around the fitting of the circular boss. about. The outer shape of the electrostatic adsorption function unit 90g is 4 mm larger than the outer shape of the coupling substrate. As a result, the creepage distance between the drive coupling substrate 90a and the coupling substrate 63a via the electrostatic adsorption function unit 90g is substantially 4 mm. Thus, leakage is prevented by keeping the creepage distance between the coupling base material 90a and the coupling base material 63a through the electrostatic attraction surface at such a distance that no leakage occurs between the members. Further, if a bias is applied beyond a voltage at which the member can maintain insulation, dielectric breakdown occurs, and adsorption force cannot be obtained. Therefore, the voltage for obtaining the electrostatic attraction force is set to be equal to or lower than the withstand voltage of the electrostatic attraction function unit 90g.

(Modification)
A modification of this embodiment will be described with reference to FIGS. In the present embodiment, the electrostatic attraction function portion 63g as a dielectric layer is arranged in the driven coupling 63, but the configuration is not limited thereto.

FIG. 7 is a schematic cross-sectional view of the driving force transmission mechanism according to the first modification of the present embodiment, and shows a state before the driving coupling 90 and the driven coupling 63 are connected. . FIG. 8 is a schematic cross-sectional view of the driving force transmission mechanism according to the first modification of the present embodiment, and shows a state where the driving coupling 90 and the driven coupling 63 are connected.
As shown in FIGS. 7 and 8, the electrostatic attraction function unit as a dielectric layer is divided into an electrostatic attraction function unit 63g (second dielectric) on the driven side coupling 63 side and electrostatic on the driving coupling 90 side. It is good also as a structure divided | segmented and arrange | positioned at the adsorption | suction function part 90g (1st dielectric material). The electrostatic attraction function part 63g has a through hole of Φ4, and aligns the through hole and the fitting hole 63h of Φ4 with the relative surface 63i of the coupling base 63a so that the above-mentioned conductive double-sided tape or the like It is fixed by. Similarly, the electrostatic adsorption function part 90g also has a Φ4 through-hole, and aligns the through-hole and the Φ4 fitting hole 90d with the relative surface 90f of the coupling base material 90a, so It is fixed with double-sided tape. When a voltage is applied, dielectric polarization occurs in each of the electrostatic adsorption function units 63g and 90g, and the drive transmission surface 63c of the electrostatic adsorption function unit 63g and the drive transmission surface 90c of the electrostatic adsorption function unit 90g are electrostatically connected to each other. Adsorbed. As a result, the drive coupling 90 and the driven coupling 63 are connected.

FIG. 9 is a schematic cross-sectional view of the driving force transmission mechanism according to the second modification of the present embodiment, and shows a state before the driving coupling 90 and the driven coupling 63 are connected. . FIG. 10 is a schematic cross-sectional view of the driving force transmission mechanism according to the first modification of the present embodiment, and shows a state where the driving coupling 90 and the driven coupling 63 are connected.
As shown in FIGS. 9 and 10, the electrostatic attraction function unit may be disposed not on the drive coupling 90 but on the driven coupling 63. The electrostatic attraction function part 63g has a through hole of Φ4, and aligns the through hole and the fitting hole 63h of Φ4 with the relative surface 63i of the coupling base 63a so that the above-mentioned conductive double-sided tape or the like It is fixed by. As described above, when a voltage is applied, dielectric polarization is generated in the electrostatic adsorption function unit 63g, and the drive transmission surface 63c of the electrostatic adsorption function unit 63g and the drive transmission surface 90c of the drive coupling 90 are electrostatically adsorbed to each other. Is done. As a result, the drive coupling 90 and the driven coupling 63 are connected.

  Next, means for detecting whether or not the drive from the drive transmission surface 90c of the apparatus main body A is transmitted to the driven transmission surface 63c of the cartridge B and determining the drive transmission state will be described. As described above, in the image forming apparatus of the coupling unit of the present embodiment, the suction surface is flat to eliminate the drive transmission backlash. In the present embodiment, in the drive coupling having the above-described configuration, the suction force is reduced and the suction surfaces are prevented from slipping to each other to prevent idling and suppress the wear of the drive transmission surface of the drive coupling. Is for.

  FIG. 15 is a block diagram of this embodiment. The image forming apparatus includes a recording unit 100, a power supply unit 103, a control unit 106, and a drive transmission detection unit 102, and the apparatus body A and the cartridge B are coupled by the suction unit 105. It is concluded through. FIG. 16 is a flow chart for explaining a series of flows for suppressing the wear of the drive surface transmission surface due to idling due to slipping of the suction surface. When the start of the printing operation is instructed, the determination unit 101 as the drive transmission state determination unit refers to a threshold value for determining the drive state of the drive force transmission mechanism from the recording unit 100 (S1). Here, the determination of the driving state of the driving force transmission mechanism means that the driving force transmission state by the driving force transmission mechanism is a state in which an electrostatic adsorption force that restricts relative movement between the couplings is generated, or the above It is determined whether or not an electrostatic attraction force that restricts relative movement has occurred. When the electrostatic attraction force that restricts the relative movement is generated, it is determined as a normal drive transmission state (first state), and when it does not occur, the abnormal drive transmission state (second state) is determined. Status). When it is determined that the driving force transmission state is abnormal, the control unit 106 causes the driving force transmission mechanism to perform an avoiding operation to avoid the abnormal transmission state from continuing.

  Next, the power supply unit 103 applies the applied bias value designated by the recording unit 100 from the control unit 106 to the suction unit 105 (S2). Next, the drive unit 104 starts driving by applying a voltage from the power supply unit to the drive unit by the control unit 106 (S3). Then, the drive transmission detection unit 102 in FIG. 15 detects the drive state (S4), and sends the detection result to the determination unit 101. The determination unit 101 in FIG. 15 compares the detection result in the drive transmission detection unit 102 with the threshold value referenced from the recording unit 100, and determines the drive transmission state (S5).

  FIG. 17 is a conceptual diagram in the case where a torque sensor is used as the torque detection unit in the detection unit, and the driving state is determined based on the torque detection result. The driving torque can be measured, for example, by attaching a rotational torque meter (such as UTMII manufactured by Unipulse Corporation) between the motor 95 and the small gear 96 in FIG. Alternatively, the torque may be measured by providing a two-point measurement point on the drum unit 61 and measuring the phase difference caused by the twist between the two points. When the process cartridge and the image forming apparatus are fastened and transmitted, the load for driving the drum and the developing roller is detected as torque. On the other hand, when the fastening is insufficient and normal drive transmission is not performed, the load from the cartridge B is not received by the suction portion on the apparatus main body A side, so the torque value detected by the torque sensor is the same as that of the process cartridge and image formation. It is smaller than when the device is fastened and transmitted. As a result of the determination, if it can be determined that the drive transmission is being performed (normal transmission state), the drive is continued (S6). If it is determined that drive transmission is not performed (abnormal transmission state), a voltage is applied between the drive coupling 90, the electrostatic adsorption function unit 90g, and the driven coupling 63 as an avoidance operation. Is stopped, the driving of the driving force transmission mechanism is stopped (S7). The driving may be stopped by stopping the motor 95 that is a driving source.

In the present embodiment, when the detected torque is smaller than a predetermined threshold value, it is determined that the drive transmission state is not established, and the idling portion is prevented from idling by stopping the drive. The magnitude of the torque described above is a value unique to the image forming apparatus and the process cartridge. (1) The torque value when the drive transmission state is not changed from the drive transmission state is set to a desired threshold value with respect to the torque value. You just have to decide. In this embodiment, the torque in the stop state is 0 Ncm, and the average torque in the drive transmission state is about 1.0 Ncm, so the threshold is set to 0.8 Ncm, which is lower than the torque in the drive transmission state.
Moreover, although the state of (1) described above changes depending on the environmental conditions and the usage history of the suction unit, a threshold value may be appropriately set according to each characteristic.

With the configuration and operation described above, it is possible to achieve a drive coupling with no rattling. Further, idling due to insufficient fastening force at the coupling portion is prevented, and wear of the coupling portion and the suction surface is suppressed. As a result, stable drive transmission can be achieved for a long time.
Here, it is needless to say that a desired drive transmission force can be obtained by appropriately selecting the area of the dielectric as the electrostatic adsorption function unit 90g and the voltage applied to the dielectric. Absent.

In this embodiment, the process cartridge in which the cleaner unit and the developing unit are integrally formed is described. However, it goes without saying that the present invention can also be applied to a configuration in which the cleaner unit and the developing unit can be independently attached to and detached from the apparatus main body as a cleaner cartridge or a developing cartridge.
Further, this configuration is more effective in a cleanerless process in which the cleaner blade is eliminated. Further, it can be suitably applied to drive coupling of the developing unit. The present invention can also be suitably applied to a multicolor image forming process.
In addition, the present invention can also be suitably applied as an electric clutch by utilizing the ON / OFF action of the electrostatic adsorption action by ON / OFF of the voltage applied to the coupling.
The functions, materials, shapes, and relative arrangements of the components described in the present embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

(Example 2)
As shown in FIG. 18, the present embodiment is characterized in that the drive detection unit 202 is provided not in the apparatus main body A but in the cartridge B. The control in the present embodiment is for preventing the idling by sliding when the attracting force is insufficient because the attracting surface is flat, and suppressing the wear of the drive transmission surface of the drive coupling.

  In this embodiment, an example in which the drive transmission means is determined by reading the rotation period of the conveying member 43 in FIG. That is, it is determined whether the drive transmission state of the drive force transmission mechanism is normal or abnormal by detecting the rotation state of the stirring member 43 as the second rotating body that rotates by the drive force transmitted by the drive force transmission mechanism. . As a means (rotation detection unit) for reading the rotation period of the conveying member 43, there is toner remaining amount detection using an optical sensor (Japanese Patent No. 2820695). In the residual toner detection technique using an optical sensor, a light transmissive transparent member is provided at a portion where a conveying member (toner stirring member) inside a toner container rotates. In this technique, the remaining amount of toner is detected by detecting the detection light transmitted from the light emitting unit through the transparent member by the light receiving unit (from the detection light receiving period of the light receiving unit). Strictly speaking, the optical residual detection is a technique for detecting the remaining amount of toner by measuring the amount of time that the toner blocks the optical path from the light emitting unit to the light receiving unit according to the rotation period of the conveying member. By reading the period when the toner shields light, the rotation period of the conveying member can be estimated, and this embodiment uses this technique for grasping the driving state.

When the applied voltage is sufficient and drive transmission is normally performed, in the toner remaining amount detection using the optical path, a pulse as shown in FIG. 19 can be obtained according to the rotation period T of the transport member 43. When the drive transmission to the conveying member 43 is not normal, the periodic pulse shown in FIG. 19 cannot be obtained. Also, immediately before the drive transmission is transmitted normally (hereinafter referred to as an indeterminate form), a pulse that does not follow the rotation period T is measured as shown in FIG. 20 (that is, the optical residual detection is performed as shown in FIGS. In this embodiment, an example in which Fourier transform is performed to determine the pulse period of the optical residual detection is shown in Fig. 21. The solid line indicates the case where the rotation period T of the conveying member is followed. The dotted line is a plot of an indefinite shape.

  When the waveform according to the rotation period T is analyzed as shown in FIG. 19, it has a peak at a frequency according to the stirring period T. On the other hand, in the case of the irregular shape shown in FIG. 20, a frequency according to the rotation period T cannot be obtained. That is, it is possible in principle to determine the drive state by paying attention to the frequency according to the rotation period T when Fourier transform is performed and observing the amplitude. Although the amplitude height is measured in FIG. 21, an equivalent analysis means such as calculating the integrated intensity of the amplitude may be used.

  As described in the first embodiment, the fastening force in the coupling portion is proportional to the width of the region where current flows between the electrodes and the applied voltage. FIG. 22 shows the relationship between the observed applied voltage and amplitude, with the area width being constant. What is necessary is just to judge that the drive transmission is normal when the amplitude of the frequency of the rotation period of the conveyance member 43 assumed is larger than the threshold value from the threshold value shown in FIG. Here, the setting of the threshold value depends on the number of pulses to be extracted by detection and the shape of the pulse, and therefore may be set appropriately for each system. In this embodiment, the pulse output from the toner remaining amount detection using light is used as the detection means. However, the present invention is not limited to this, and any light can be used as long as it is a means for grasping the driving state from within the process cartridge. The toner remaining amount detecting means used is not limited.

  As a result of the present embodiment, even if the drive detection unit 202 is provided in the cartridge B, the same effect as in the first embodiment can be obtained. Further, instead of expensive detection means like the torque sensor shown in the first embodiment, it is possible to reduce the cost by substituting other signals output from the process cartridge with reading drive transmission detection means.

Example 3
The third embodiment is characterized by determining an applied bias that achieves a fastening force necessary to prevent idling as well as preventing and detecting idling compared to the first embodiment. Although the present embodiment is the same as the first embodiment in terms of configuration, the control for determining the applied bias is different.

  The control flow of this embodiment will be described with reference to FIG. The flow from (S8 to 11) up to (S12) is compared with (S1 to S4) in the first embodiment until the observation result is compared with the threshold value to determine whether it is in the drive transmission state (S12). Here, when the determination unit 101 determines that the drive transmission state is not set (S12), the control unit 106 adjusts the applied voltage. As described in the first embodiment, since the fastening force in the coupling portion is proportional to the width of the region where current flows between the electrodes and the applied voltage, in this embodiment, the control unit increases the applied voltage by ΔV [V]. Then, the fastening force in the coupling part is increased (S13). In this embodiment, ΔV is 40V. After ΔV [V] increases, drive detection and determination are performed again (S11, S12). The same operation is repeated until the determination unit 101 determines that it is in the drive transmission state, and the applied voltage of the coupling unit is determined (S14).

  Although the applied voltage is controlled in the present embodiment, the above-described control can be similarly applied to a configuration in which the current value is controlled. By performing the control of this embodiment, even when the energization characteristics of the dielectric layer of the adsorption part change depending on the usage environment and usage conditions, the adsorption force decreases and the adsorption surface slips and the idle rotation occurs. Can be prevented. In addition to suppressing wear on the drive transmission surface of the drive coupling, it is possible to form a stable image by determining an applied bias that maintains a drive transmission state during image formation. With respect to the ΔV, since the current-carrying characteristic with respect to the applied voltage changes depending on the volume resistance of the member of the suction portion and the use environment, an appropriate ΔV may be set by performing an experiment in advance. Further, if the ΔV amount is large, the total control time can be reduced, and if the ΔV amount is small, the accuracy can be improved, and the step amount may be appropriately determined according to the purpose.

(Example 4)
The present embodiment is characterized in that an applied bias that can prevent an applied bias from being excessively high and suppress energization deterioration is determined with respect to the third embodiment. In this embodiment, the configuration is the same as that of the first embodiment, but the control method is different.

  The control flow of the present embodiment will be described with reference to FIG. Deterioration of energization is the change of electrical characteristics such as electrical resistance as a result of continuous direct current flowing through a conductive resin such as rubber.If excessive bias is continuously applied, the deterioration of energization is promoted and sufficient. It is difficult to obtain an adsorption force, which is undesirable. Therefore, it is necessary to avoid applying an excessive bias while applying a bias capable of obtaining an attractive force necessary for driving.

  The control flow of the present embodiment will be described with reference to FIG. The flow is the same as (S1 to S4) in the first embodiment (S15 to S4) up to (S19) until the observation result is compared with the threshold value and it is determined whether the state is the drive transmission state (S19). Here, when the determination unit 101 determines that the drive transmission state is set (S19), the control unit 106 decreases the applied voltage by ΔV [V] (S20). In this embodiment, ΔV is 40V. After the applied voltage is decreased by ΔV [V], drive detection and determination are performed again (S18, S19). Until the determination unit 101 determines that the drive transmission state is not established, the control unit 106 repeatedly performs the same operation, whereby the maximum applied voltage Vmax that is not in the drive transmission state is determined by the width of the error ΔV [V]. In this example, Vmax was 850V. The control unit determines the applied bias by a value obtained by increasing ΔV [V] with respect to Vmax so that the drive transmission state is obtained and the minimum applied bias is obtained (S21). That is, the magnitude of the applied voltage is set as small as possible within a range in which the normal transmission state of the driving force transmission mechanism can be maintained. That is, in this embodiment, 890 [V] (850 [V] +40 [V]) is determined as the applied bias. As a result of the present embodiment, in addition to the effects of the first embodiment, it is possible to suppress energization deterioration by suppressing application of an excessive bias to the attracting portion.

  With respect to ΔV, the current sensitivity to the applied voltage varies depending on the volume resistance of the member of the suction portion and the use environment, so an appropriate ΔV may be set by conducting an experiment in advance. Further, if the ΔV amount is large, the total control time can be reduced, and if the ΔV amount is small, the accuracy can be improved, and the step amount may be appropriately determined according to the purpose. Although the applied voltage is controlled in the present embodiment, the above-described control can be similarly applied to a configuration for controlling current. Further, the algorithm of the present embodiment is not limited to the drive detection method described in the first and second embodiments.

  62 ... drum (photosensitive drum), 63 ... driven coupling, 90 ... driving coupling, 90g ... electrostatic adsorption function unit, 95 ... motor, 101 ... judgment unit, 106 ... control unit, 201 ... judgment unit, 206 ... Control unit, A ... device body, B ... cartridge

Claims (17)

A device body with a power source;
A cartridge that is detachable from the apparatus main body, and includes a rotating body that rotates by a driving force transmitted from the power source;
A driving force transmission mechanism for transmitting a driving force from the power source to the rotating body,
A first coupling member that rotates with a driving force transmitted from the power source;
A second coupling member coupled to the rotating body;
A dielectric sandwiched between the first coupling member and the second coupling member;
A voltage applying unit for applying a voltage between the first coupling member, the dielectric, and the second coupling member;
With
By applying a voltage from the voltage application unit, an electrostatic attraction force that attracts the first coupling member and the second coupling member to each other via the dielectric is generated, and the rotation direction of the first coupling member A driving force transmission mechanism for restricting relative movement between the first coupling member and the second coupling member in
A control unit for controlling the driving force transmission mechanism;
The transmission state of the driving force of the driving force transmission mechanism is the first state where the electrostatic attraction force that restricts the relative movement is generated, or the electrostatic attraction force that restricts the relative movement occurs. A state determination unit for determining whether the second state is not,
An image forming apparatus comprising:
When the state determination unit determines that the state is the second state, the control unit causes the driving force transmission mechanism to perform an avoidance operation that prevents the second state from continuing.   The image forming apparatus according to claim 1, wherein the avoidance operation is an operation in which the driving force transmission mechanism stops driving.   The image forming apparatus according to claim 1, wherein the avoiding operation is an operation of changing a voltage applied by the voltage application unit to a larger voltage.   The state determination unit includes a torque detection unit that detects torque generated in the driving force transmission mechanism by the voltage application of the voltage application unit, and the torque detected by the torque detection unit does not reach a predetermined value. The image forming apparatus according to claim 1, wherein the image forming apparatus determines that the second state is present. The cartridge further includes a second rotating body that rotates by a driving force transmitted from the second coupling,
The state determination unit includes a rotation detection unit that detects a rotation state of the second rotating body, and determines that the rotation state detected by the rotation detection unit is the second state when the rotation state is abnormal. The image forming apparatus according to any one of claims 1 to 3. The cartridge includes a storage chamber that stores toner, and a toner stirring member that rotates inside the storage chamber as the second rotating body,
The rotation detection unit is an optical sensor that detects a rotation state of the toner stirring member,
6. The image according to claim 5, wherein the state determination unit determines whether or not the rotation state is abnormal based on a period in which the light receiving unit of the optical sensor receives detection light from the light emitting unit. Forming equipment. The said control part changes the voltage which the said voltage application part applies the said voltage to a smaller voltage when the said state determination part judges as the said 1st state, The any one of Claims 1-6 characterized by the above-mentioned. The image forming apparatus according to claim 1. The voltage application unit has a power source connected to the first coupling member,
The second coupling member is on the ground side with respect to the first coupling member;
The junction of the first coupling member with the dielectric is one electrode, and the junction of the second coupling member with the dielectric is the other electrode,
When the voltage is applied from the voltage application unit, electrostatic induction occurs in the one electrode, dielectric polarization occurs in the dielectric, and electrostatic induction occurs in the other electrode, thereby generating the electrostatic attraction force. The image forming apparatus according to claim 1.   The said 1st coupling member, the said dielectric material, and the said 2nd coupling member are mutually joined by the surface perpendicular | vertical to the rotating shaft of the said 1st coupling member, respectively. The image forming apparatus according to claim 1. The dielectric is fixed to the first coupling member;
The dielectric and the second coupling member are caused by the dielectric polarization generated in the dielectric by the voltage application of the voltage application unit and the electrostatic induction generated in the junction of the dielectric of the second coupling member. The image forming apparatus according to claim 1, wherein the image forming apparatuses are electrostatically attracted to each other. The dielectric is fixed to the second coupling member;
The dielectric and the first coupling member are caused by electrostatic induction generated at a joint portion of the first coupling member with the dielectric and a dielectric polarization generated in the dielectric due to voltage application of the voltage applying unit. The image forming apparatus according to claim 1, wherein the image forming apparatuses are electrostatically attracted to each other. The dielectric includes a first dielectric fixed to the first coupling member, and a second dielectric fixed to the second coupling member,
The first dielectric and the second dielectric are joined to each other on a plane perpendicular to the rotation axis of the first coupling member;
The first dielectric and the second dielectric are electrostatically attracted to each other by dielectric polarization generated in the first dielectric and the second dielectric, respectively, by applying a voltage from the voltage application unit. The image forming apparatus according to claim 1.   It is inserted into a through-hole provided in the dielectric, and one end is fitted into a recess provided in the first coupling member and the other end is fitted into a recess provided in the second coupling member. The image forming apparatus according to claim 1, further comprising a centering member.   The image forming apparatus according to claim 13, wherein the centering member is an insulating member. The through hole is substantially the same diameter as the outer diameter of the centering member,
The image forming apparatus according to claim 13, wherein the recess is chamfered so that the opening is larger than the through hole. The joint surface between the first coupling member and the dielectric, and the joint surface between the dielectric and the second coupling member are perpendicular to the rotation axis of the first coupling member and have an inner diameter and an outer diameter. The image forming apparatus according to claim 1, wherein the image forming apparatus has an annular surface.   The image forming apparatus according to claim 1, wherein the rotating body is an image carrier for carrying a developer image transferred to a recording material.