JP6127780B2 - Developing device, process unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device mounted on an image forming apparatus, a process unit including the developing device, and an image forming apparatus.

  In an image forming apparatus such as a copying machine or a printer, in order to prevent the occurrence of abnormal images such as unevenness in image density or defects, toner as a developer is uniformly transferred from the developing roller to the surface of the photosensitive member without unevenness. It is necessary. For this purpose, the photosensitive member and the developing roller must be in contact with each other at a target position with a uniform contact pressure in the axial direction.

  In order to stably bring the developing roller into contact with the photosensitive member, for example, a developing unit (developing device) having a developing roller and a photosensitive member unit having a photosensitive member are arranged on both end sides in the axial direction of the developing roller. There has been proposed a structure in which the developing unit is pivotably connected, and the developing unit is urged toward the photoconductor unit by an urging member such as a spring at both ends in the axial direction (see Patent Document 1 below).

  Incidentally, the developing device is generally provided with an electrode member that forms a power feeding path for applying a developing bias to the developing roller. The electrode member provided in the developing device is brought into conduction by being in contact with the electrode member on the power supply side, and power can be supplied from the power source to the power-supplied member such as the developing roller.

  However, when the electrode member as described above is provided on one side of the developing device (one end side in the axial direction of the developing roller), the frictional resistance caused by the contact between the electrode member and the electrode member on the power source side causes the developing device to There is a possibility that the balance of the urging forces of the urging members provided on both sides may be lost. As a result, if the developing roller cannot be brought into contact with the photosensitive member at a target position or a target contact pressure, an abnormal image may be generated. Further, since the frictional force between the electrode members varies depending on the surface state of the electrode members, the initial position, and the temperature and humidity environment, it is difficult to determine the biasing force of the biasing member in consideration of the frictional force.

  SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a developing device and a process unit capable of urging a developer carrying member with respect to a photosensitive member with a target position and urging force even in a configuration in which an electrode member is provided on one side. And an image forming apparatus.

  In order to solve the above problems, the present invention provides a developer carrier for supplying a developer to the surface of a photoreceptor, a biasing member for biasing the developer carrier to the photoreceptor, and the developer carrier. A developing-side electrode member that contacts a power-supply-side electrode member on one end side in the axial direction and feeds power to the developing-side power-supplied member, on the side where the developing-side electrode member is provided Two urging members are provided, and when viewed from the axial direction of the developer carrying member, a contact portion of the developing-side electrode member with respect to the power-side electrode member is positioned between the two urging members. It is characterized by comprising.

  According to the present invention, even in the configuration in which the development side electrode member is provided on one side of the development device, the influence of the frictional force at the contact portion between the development side electrode member and the power supply side electrode member can be reduced. The device can be held in the correct posture. As a result, the developer carrying member can be arranged at a target position with respect to the photosensitive member and can be biased with a target biasing force, so that the occurrence of an abnormal image can be prevented.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus to which the present invention is applied. It is a figure which shows the state which opened the upper cover. It is a figure which shows the state which opened the upper cover and the intermediate | middle cover. It is a schematic sectional drawing of a process unit. FIG. 3 is a diagram illustrating a driving system for a photoconductor unit and a developing unit. FIG. 3 is a diagram illustrating a driving system of a photosensitive unit, a developing unit, and an apparatus main body. It is the perspective view which looked at the process unit from the drive side. It is the perspective view which looked at the process unit from the non-driving side. FIG. 4 is a diagram illustrating a configuration in which a developing unit does not slide with respect to a photoconductor unit and is simply rotatable on the non-driving side. FIG. 4 is a diagram illustrating a configuration in which a developing unit is slidable with respect to a photosensitive unit on the non-driving side. It is a perspective view which shows the structure of the non-driving side of a process unit. 2A and 2B are diagrams showing the opposite driving sides of the photosensitive unit and the developing unit, in which FIG. 1A shows a state before the photosensitive unit and the developing unit are assembled, and FIG. 2B shows the photosensitive unit and the developing unit. It is a figure which shows the state which assembled | attached. It is a figure which shows the example which comprised the image development side electrode member with the leaf | plate spring. It is a figure which shows the example which comprised the photosensitive side electrode member with the electrode member which provided the conductor in the front-end | tip of a coil spring. FIG. 6 is a side view of the developing unit on the non-driving side. It is a simplified diagram showing the relationship between the position of the contact portion between the electrode members and the biasing force of the coil spring. It is a simplified diagram showing an example of change of the position of the contact portion. It is a figure which shows the structure which apply | coated the electroconductive lubricant to the said contact part. It is a figure which shows the structure which interposed the conductive carbon terminal in the said contact part. It is a simplified diagram showing a configuration of a comparative example. It is a simplification figure showing the composition of another comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings for explaining the embodiments of the present invention, constituent elements such as members and components having the same function or shape are described once by giving the same reference numerals as much as possible. Then, the explanation is omitted.

  First, an overall configuration and operation of a color laser printer according to an embodiment of the present invention will be described with reference to FIG. However, the present invention is not limited to this. The configuration of the present invention can also be applied to an image forming apparatus such as a monochrome printer, other printers, a copier, a facsimile, or a complex machine thereof.

  As shown in FIG. 1, four process units 1Y, 1M, 1C, and 1Bk as image forming units are detachably mounted on an apparatus main body (image forming apparatus main body) 100 of the color laser printer. Each process unit 1Y, 1M, 1C, 1Bk contains toners of different colors of yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to the color separation components of the color image. Other than that, the configuration is the same.

  Specifically, each of the process units 1Y, 1M, 1C, and 1Bk converts the photoreceptor 2, the charging roller 3 as a charging unit that charges the surface of the photoreceptor 2, and the latent image on the photoreceptor 2 into a visible image. The developing device 4 is a developing unit that performs cleaning, and the cleaning blade 5 is a cleaning unit that cleans the surface of the photoreceptor 2. An exposure device 6 for exposing the surface of the photoconductor 2 is provided at a position facing each photoconductor 2. In the present embodiment, an LED unit is used as the exposure device 6.

  A toner cartridge 30 as a developer container that contains toner as a developer is detachably mounted above each developing device 4. Each toner cartridge 30 contains toner of the same color as the toner in the corresponding developing device 4. When the toner in the developing device 4 falls below a predetermined amount, the toner is supplied from the toner cartridge 30. ing.

  A transfer device 7 is disposed below each photoconductor 2. The transfer device 7 has an intermediate transfer belt 8 formed of an endless belt as an intermediate transfer member. The intermediate transfer belt 8 is stretched around a driving roller 9 and a driven roller 10 as support members, and when the driving roller 9 rotates counterclockwise in the drawing, the intermediate transfer belt 8 travels (rotates) in a circle. It is configured as follows.

  A primary transfer roller 11 as a primary transfer unit is disposed at a position facing each photoconductor 2. Each primary transfer roller 11 presses the inner peripheral surface of the intermediate transfer belt 8 at each position, and a primary transfer nip is formed at a place where the pressed portion of the intermediate transfer belt 8 and each photoconductor 2 are in contact with each other. Has been. Each primary transfer roller 11 is connected to a power source (not shown), and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the primary transfer roller 11.

  A secondary transfer roller 12 as a secondary transfer unit is disposed at a position facing the drive roller 9. The secondary transfer roller 12 presses the outer peripheral surface of the intermediate transfer belt 8, and a secondary transfer nip is formed at a location where the secondary transfer roller 12 and the intermediate transfer belt 8 are in contact with each other. Similarly to the primary transfer roller 11, the secondary transfer roller 12 is connected to a power source (not shown), and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to the secondary transfer roller 12. It has become so.

  A belt cleaning device 13 for cleaning the surface of the intermediate transfer belt 8 is disposed on the outer peripheral surface on the right end side of the intermediate transfer belt 8 in the drawing. A waste toner transfer hose (not shown) extending from the belt cleaning device 13 is connected to an entrance of a waste toner container 14 disposed below the transfer device 7.

  A lower part of the apparatus main body 100 is provided with a paper feed tray 15 that stores paper P as a recording medium, a paper feed roller 16 that feeds the paper P from the paper feed tray 15, and the like. Here, the paper P includes thick paper, postcard, envelope, plain paper, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, and the like. Further, an OHP sheet, an OHP film, or the like can be used as a recording medium.

  A pair of paper discharge rollers 17 for discharging the paper to the outside and a paper discharge tray 18 for stocking the paper discharged by the paper discharge roller 17 are provided on the upper portion of the apparatus main body 100.

  In the apparatus main body 100, a transport path R for transporting the paper P from the paper feed tray 15 through the secondary transfer nip to the paper discharge tray 18 is disposed. In the transport path R, a pair of registration rollers 19 are provided on the upstream side in the paper transport direction from the position of the secondary transfer roller 12 as a timing roller for transporting the paper to the secondary transfer nip by measuring the transport timing. Yes. In addition, a fixing device 20 that fixes an image on a sheet is provided downstream of the position of the secondary transfer roller 12 in the sheet conveyance direction.

Next, a basic operation of the printer according to the present embodiment will be described with reference to FIG.
When the image forming operation is started, the photosensitive members 2 of the process units 1Y, 1M, 1C, and 1Bk are rotated in the clockwise direction in FIG. 1, and the surface of each photosensitive member 2 is made to have a predetermined polarity by the charging roller 3. It is charged like this. Based on image information from a reading device or a computer (not shown), the exposure device 6 irradiates the charged surface of each photoconductor 2 with laser light, and an electrostatic latent image is formed on the surface of each photoconductor 2. At this time, the image information to be exposed on each photoconductor 2 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. As the electrostatic latent image formed on the photosensitive member 2 is supplied with toner by each developing device 4, the electrostatic latent image is visualized (visualized) as a toner image.

  When the image forming operation is started, the intermediate transfer belt 8 is driven to rotate by the drive roller 9 that stretches the intermediate transfer belt 8 being rotated. Also, a primary transfer nip between each primary transfer roller 11 and each photoreceptor 2 is applied to each primary transfer roller 11 by applying a constant voltage or a voltage controlled by a constant current opposite to the charging polarity of the toner. A transfer electric field is formed.

  Thereafter, when each color toner image on the photoconductor 2 reaches the primary transfer nip as the photoconductor 2 rotates, the toner image on each photoconductor 2 is formed by the transfer electric field formed in the primary transfer nip. Are sequentially superimposed and transferred onto the intermediate transfer belt 8. Thus, a full-color toner image is carried on the surface of the intermediate transfer belt 8. Further, the toner on each photoreceptor 2 that could not be transferred to the intermediate transfer belt 8 is removed by the cleaning blade 5.

  In the lower part of the apparatus main body 100, the paper feed roller 16 starts to rotate, and the paper P is sent out from the paper feed tray 15 to the transport path R. The paper P sent to the transport path R is temporarily stopped by the registration roller 19.

  Thereafter, rotation of the registration roller 19 is started at a predetermined timing, and the paper P is conveyed to the secondary transfer nip in accordance with the timing when the toner image on the intermediate transfer belt 8 reaches the secondary transfer nip. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 8 is applied to the secondary transfer roller 12, thereby forming a transfer electric field in the secondary transfer nip. . Then, the toner images on the intermediate transfer belt 8 are collectively transferred onto the paper P by this transfer electric field. The residual toner on the intermediate transfer belt 8 that could not be transferred onto the paper P is removed by the belt cleaning device 13, and the removed toner is transported to the waste toner container 14 and collected.

  Thereafter, the paper P on which the toner image is transferred is conveyed to the fixing device 20, and the toner image on the paper P is fixed on the paper P in the fixing device 20. Then, the paper P is discharged out of the apparatus by the pair of paper discharge rollers 17 and stocked on the paper discharge tray 18.

  The above description is an image forming operation when a full-color image is formed on a sheet. A single-color image is formed using any one of the four process units 1Y, 1M, 1C, and 1Bk, or two Alternatively, it is possible to form two-color or three-color images using three process units.

  As shown in FIG. 1, the printer according to the present embodiment includes an upper cover 101 as a first cover provided on the upper portion of the apparatus main body 100 and a first cover provided on the inner side (lower side) of the upper cover 101. And an intermediate cover 102 as two covers. The upper cover 101 and the intermediate cover 102 are configured to be openable and closable by rotating around support shafts 103 and 104 provided in the apparatus main body 100, respectively. 2 shows a state in which the upper cover 101 is opened, and FIG. 3 further shows a state in which the intermediate cover 102 is opened.

  The intermediate cover 102 is formed with a container mounting portion 120 to which a plurality of toner cartridges 30 can be mounted. The unit mounting portion 130 formed on the inner side (lower side) of the intermediate cover 102 can accommodate the process units 1Y, 1M, 1C, and 1Bk for each color.

  As shown in FIG. 2, when the upper cover 101 is opened, each toner cartridge 30 can be attached to and detached from the intermediate cover 102 from above.

  Further, as shown in FIG. 3, when the intermediate cover 102 is opened, the toner cartridges 30 can be integrally retracted from above the process units 1Y, 1M, 1C, and 1Bk. At this time, since each exposure device 6 is retracted from above each photoconductor 2 together with the intermediate cover 102, each process unit 1Y, 1M, 1C, 1Bk can be attached and detached from above. As described above, in the present embodiment, the process units 1Y, 1M, 1C, and 1Bk can be attached and detached without removing the toner cartridge 30 from the intermediate cover 102, and exchanging workability is excellent.

FIG. 4 is a schematic sectional view of the process unit.
In the present embodiment, the process unit 1 (the alphabets Y, M, C, and Bk indicating the respective colors are omitted) is mainly composed of two modules. One is a photoreceptor unit (first unit) U1 having the photoreceptor 2, the charging roller 3, the cleaning blade 5, and the like. The other is a developing unit (second unit) U2 having the developing device 4.

  The developing unit U2 (developing device 4) includes a housing 40 that contains toner and the like, a developing roller 41 as a developer carrying member that carries the toner, and a developer supply member that supplies toner to the developing roller 41. A supply roller 42; a regulating blade 43 as a regulating member that regulates the thickness of toner carried on the developing roller 41; a conveying screw 44 as a conveying member that conveys toner; and an agitating member that agitates toner An agitator 45 is provided.

  An opening 40c is formed in the lower portion of the housing 40 facing the photoreceptor 2, and a developing roller 41 is rotatably provided in the opening 40c. The developing roller 41 is made of a metal core, an elastic layer made of an elastic member or a foamed elastic member disposed on the outer periphery of the core, an acrylic resin, a silicone resin, or the like disposed on the outer periphery of the elastic layer. And a surface layer (resin coat layer). The developing roller 41 may not have a surface layer.

  The supply roller 42 is constituted by a sponge roller in which an elastic layer made of a foamed elastic member is disposed on the outer periphery of a metal cored bar. Examples of the material for the foamed elastic member include flexible urethane foam, silicone, and foamed polymer. Moreover, you may use what adjusted the resistance value by adding a electrically conductive material to these materials. The supply roller 42 is in contact with the developing roller 41, and a nip (hereinafter referred to as “supply nip”) is formed between the rollers 41 and 42.

  The regulating blade 43 is made of, for example, a metal plate such as SUS having a thickness of about 0.1 mm. The front end of the regulating blade 43 is in contact with the surface of the developing roller 41 to form a nip (hereinafter referred to as “regulating nip”).

  When an instruction to start an image forming operation is given, the toner in the housing 40 is stirred by the agitator 45 and supplied to the supply roller 42 by the conveying screw 44. The toner supplied to the supply roller 42 is frictionally charged by the friction between the supply roller 42 and the developing roller 41 at the supply nip and is supplied to the surface of the developing roller 41.

  The toner carried on the developing roller 41 passes through the regulation nip of the regulation blade 43, thereby being triboelectrically charged at the same time as the thickness of the toner layer is regulated. When the toner on the developing roller 41 is conveyed to a position (development region) facing the photoconductor 2, the toner is applied on the photoconductor 2 by the force of the electric field generated between the photoconductor 2 and the developing roller 41. A toner image is formed by transferring to an electrostatic latent image.

Next, a drive system for the photosensitive unit and the developing unit will be described with reference to FIGS.
As shown in FIG. 5, the axial ends of the developing roller 41 and the supply roller 42 are rotatably supported by a pair of side wall portions 40a and 40b included in the housing 40 of the developing unit U2. Further, both ends in the axial direction of the photoreceptor 2 are rotatably supported by a pair of support walls 50a and 50b included in the housing 50 of the photoreceptor unit U1.

  A photoreceptor gear G1 is coaxially provided at one end of the photoreceptor 2. A developing gear G2 is coaxially provided at one end of the developing roller 41 on the same side, and the developing gear G2 meshes with the photoconductor gear G1 so that power can be transmitted between them.

  In FIG. 6, G3 is a drive gear of a drive motor M provided in the apparatus main body, and G4 to G6 are a plurality of transmission gears provided in the apparatus main body. When the process unit 1 is mounted on the apparatus main body, as shown in FIG. 6, the photoconductor gear G1 is connected to the drive gear G3 via a plurality of transmission gears G4 to G6. When the driving motor M is driven in this state, the driving force is transmitted from the driving gear G3 to the photosensitive member gear G1 via the transmission gears G4 to G6, and further to the developing gear G2. Yes.

  As shown in FIG. 5, a supply gear G7 that meshes with the developing gear G2 is also provided coaxially at one end of the supply roller 42, and the supply roller 42 is connected to the developing roller 41 via the supply gear G7. The driving force is transmitted from. A transmission gear G8 for transmitting a driving force to the conveying screw 44 and the agitator 45 is provided at the end of the supply roller 42 opposite to the end where the supply gear G7 is provided. The transmission gear G8 is provided outside the right side wall portion 40b of the developing unit U2 in FIG. 5 and is covered with a gear cover 46.

FIG. 7 is a perspective view of the process unit as viewed from the side on which the photoconductor gear and the development gear are provided (hereinafter referred to as “drive side”).
As shown in FIG. 7, a pin-shaped rotating shaft 40d having a circular cross section is provided at the lower part of the side wall 40a on the driving side of the developing unit U2. On the other hand, a circular hole 50c into which the rotating shaft 40d of the developing unit U2 can be inserted is provided in the lower part of the driving side support wall 50a of the photosensitive unit U1. By inserting the rotating shaft 40d into the hole 50c, the driving side wall portion 40a of the developing unit U2 is illustrated with respect to the driving side support wall 50a of the photosensitive unit U1 through the rotating shaft 40d and the hole 50c. 7 is assembled so as to be rotatable in the directions of arrows A and B.

  Further, a drive side coil spring 51 as an urging member is provided on the drive side side wall portion 40a of the developing unit U2. Of the both ends of the drive side coil spring 51, one is locked to a locking portion 40e provided on the upper portion of the side wall portion 40a of the developing unit U2, and the other is provided on the upper portion of the support wall 50a of the photosensitive unit U1. The locking portion 50d is locked. The driving side coil spring 51 is stretched between the engaging portions 40e and 50d, and the developing roller 41 is biased toward the photosensitive member 2 by the tensile force of the driving side coil spring 51. .

FIG. 8 is a perspective view of the process unit as viewed from the side opposite to the driving side (hereinafter referred to as “non-driving side”).
As shown in FIG. 8, a pin-shaped rotational movement shaft 40f having a circular cross section is provided below the side wall portion 40b on the side opposite to the driving side of the developing unit U2 and opposite to the driving side rotational shaft 40d. ing. On the other hand, a linear groove 50e into which the rotational movement shaft 40f of the developing unit U2 can be inserted is provided below the support wall 50b on the counter drive side of the photoconductor unit U1 so as to approach and separate from the photoconductor 2. ing. By inserting the rotational movement shaft 40f into the groove 50e, the side wall portion 40b on the counter drive side of the developing unit U2 is supported on the counter drive side support wall 50b of the photoreceptor unit U1 via the rotational movement shaft 40f and the groove 50e. On the other hand, it can be moved in the direction of arrows C and D in the figure, and can be rotated in the directions of arrows S and T in the figure. Here, the groove 50e is a through-hole penetrating the support wall 50b on the non-driving side, but may have a groove shape having a bottom.

  Further, a first counter driving side coil spring 52 and a second counter driving side coil spring 53 are provided as biasing members on the counter driving side of the developing unit U2. The first counter driving side coil spring 52 is provided on the upper side of the developing unit U2 on the counter driving side, and the second counter driving side coil spring 53 is provided on the lower side of the developing unit U2 on the counter driving side.

  Specifically, one end of the first counter driving side coil spring 52 is locked to a locking portion 46a provided on the upper portion of the gear cover 46 of the developing unit U2, and the other end is counter driven of the photosensitive unit U1. It is latched by the latching | locking part 50f provided in the upper part of the cover member 56 (refer FIG. 7) attached to the outer side of the side support wall 50b. In FIG. 8, the cover member 56 is not shown. As described above, the first counter driving side coil spring 52 is stretched between the two locking portions 46a and 50f, and the developing roller is pulled by the tensile force of the first counter driving side coil spring 52. 41 is urged toward the photosensitive member 2 side.

  One end portion of the second counter driving side coil spring 53 is engaged with the rotational movement shaft 40f provided at the lower portion of the side wall portion 40b on the counter driving side of the developing unit U2, and the other end portion of the photosensitive unit U1. It is latched by the latching | locking part 50g provided in the lower part of the support wall 50b by the side of a counter drive. The second counter driving side coil spring 53 is stretched between the rotary moving shaft 40f and the locking portion 50g, and the tensile force of the second counter driving side coil spring 53 is also developed by the developing roller 41. Acts as an urging force for urging the photosensitive member 2 toward the photosensitive member 2. Here, the rotational movement shaft 40f also functions as a locking portion that locks one end of the second counter-driving side coil spring 53, but a separate locking portion may be provided.

  As described above, in the present embodiment, the developing unit U2 is urged against the photosensitive unit U1 on both the driving side and the counter driving side by the driving side coil spring 51 and the counter driving side coil springs 52 and 53. As a result, the developing roller 41 is urged toward the photoconductor 2 at both axial end portions thereof, and comes into contact with the photoconductor 2 with a predetermined contact pressure. The biasing forces of the driving side coil spring 51 and the counter driving side coil springs 52 and 53 are adjusted so that the contact pressure of the developing roller 41 with respect to the photosensitive member 2 is uniform in the axial direction.

  In particular, in the present embodiment, on the opposite drive side, the developing unit U2 is slidable with respect to the photoreceptor unit U1 via the rotational movement shaft 40f and the groove 50e. Even if twist occurs between the left and right side plates, the influence of the twist on the contact state of the developing roller 41 can be reduced.

  On the other hand, as in the configuration shown in FIG. 9, on the counter-driving side, the developing unit U2 does not slide relative to the photosensitive unit U1, but can simply rotate via the rotating shaft 40u inserted into the hole 50u. If a relative twist occurs between both sides of each of the units U1 and U2, the contact position of the developing roller 41 with respect to the photoreceptor 2 is shifted from the normal contact position. Specifically, in FIG. 9, (a) shows a state in which each unit U1, U2 is not twisted, but as shown in FIGS. 9 (b), (c), both sides of each unit U1, U2 are shown. When a relative twist occurs in the direction indicated by the arrows in the figure (the rotation direction about the rotation axis of the photosensitive member 2), the respective contact positions V1 on the opposite ends of the developing roller 41 with respect to the photosensitive member 2 , V2 varies in the circumferential direction of the photosensitive member 2. This is because, in the configuration shown in FIG. 9, the developing unit U2 follows the twist of the photosensitive unit U1 because the developing unit U2 cannot slide relative to the photosensitive unit U1 on the non-driving side.

  On the other hand, in the present embodiment shown in FIG. 10, as shown in FIGS. 10B and 10C, even if the photoconductor unit U1 is twisted, the rotational movement shaft 40f is in the groove 50e on the non-driving side. By sliding, it is possible to avoid the development unit U2 following the twist of the photosensitive unit U1. As a result, the contact positions V1 and V2 of the developing roller 41 with respect to the photoreceptor 2 can be maintained at the same position on the driving side and the non-driving side.

  In this embodiment, the developing unit U2 is provided with the rotation shaft 40d and the rotational movement shaft 40f, and the photosensitive unit U1 is provided with the hole 50c and the groove 50e. On the contrary, the hole and groove are provided in the developing unit U2. In addition, the photosensitive unit U1 may be provided with a rotational shaft and a rotational movement shaft inserted into these.

  Further, as shown in FIG. 8, on the non-driving side, two electrode members 54 constituting a conduction path for supplying power from a power source (high voltage base) (not shown) on the apparatus main body side to the developing roller 41 are provided. , 55 are provided. One electrode member 54 is attached to the support wall 50b on the counter drive side of the photoreceptor unit U1, and the other electrode member 55 is attached to the gear cover 46 of the developing unit U2. As described above, the conductive path is divided into the electrode member 54 on the photosensitive unit U1 side and the electrode member 55 on the development unit U2 side, so that the assemblability, operability, and exchange of each unit U1, U2 are made. Improves. In the following description, the electrode member 54 on the photoreceptor unit U1 side is referred to as a photosensitive side electrode member 54, and the electrode member 55 on the development unit U2 side is referred to as a development side electrode member 55.

FIG. 11 is a perspective view showing the configuration of the process unit on the non-driving side.
In FIG. 11, the support wall 50b on the counter-drive side of the photoconductor unit U1 shown in FIG. 8 is not shown.
The photosensitive side electrode member 54 and the development side electrode member 55 are each formed by bending a thin metal plate. The photosensitive-side electrode member 54 includes an inner portion 54a disposed on the inner side of the support wall 50b on the counter driving side of the photoconductor unit U1, an outer portion 54b disposed on the outer side of the supporting wall 50b on the counter driving side, It has a bent part 54c that connects the inner part 54a and the outer part 54b. Similarly, the development-side electrode member 55 includes an inner portion 55a disposed inside the gear cover 46 of the development unit U2, an outer portion 55b disposed outside the gear cover 46, an inner portion 55a, and an outer portion. And a bent portion 55c for connecting to 54b.

  The development-side electrode member 55 is in contact with the shaft end portion (end portion of metal cored bar) 41a of the developing roller 41 at the inner side portion 55a. The development side electrode member 55 is in contact with the inner side portion 54a of the photosensitive side electrode member 54 at the outer side portion 55b. The outer portion 54b of the photosensitive electrode member 54 comes into contact with an electrode member (not shown) provided on the apparatus main body side when the process unit 1 is mounted on the apparatus main body.

12A is a diagram illustrating a state before the photosensitive unit and the developing unit are assembled, and FIG. 12B is a diagram illustrating a state in which the photosensitive unit and the developing unit are assembled.
As shown in FIG. 12A, the inner side 54a of the photosensitive side electrode member 54 includes a parallel part 54a1 parallel to the inner surface of the support wall 50b on the counter driving side of the photosensitive unit U1, and the inner surface of the support wall 50b on the counter driving side. And an inclined portion 54a2 inclined with respect to the angle. The inclined portion 54a2 is a leaf spring that is inclined so as to be separated from the inner surface of the support wall 50b on the counter drive side toward the assembly direction H of the developing unit U2 with respect to the photoreceptor unit U1. For this reason, the inclined portion 54a2 can be elastically deformed in the direction of approaching and separating from the support wall 50b on the counter driving side. The tip of the inclined portion 54a2 is disposed on the inner side of the surface J on which the outer portion 55b of the developing-side electrode member 55 is disposed when the developing unit U2 is assembled to the photoreceptor unit U1. Thus, when the developing unit U2 is assembled, the inclined portion 54a2 comes into contact with the outer side portion 55b of the developing side electrode member 55.

  As shown in FIG. 12B, when the developing unit U2 is assembled, when the outer portion 55b of the developing side electrode member 55 contacts the inclined portion 54a2 of the photosensitive side electrode member 54, the inclined portion 54a2 is pushed outward. Elastically deforms. In the state where the assembly of the developing unit U2 is completed, the inclined portion 54a2 is brought into contact with the outer side portion 55b of the developing-side electrode member 55 with a predetermined contact pressure by the restoring force, thereby ensuring electrical conductivity. When the photosensitive side electrode member 54 and the development side electrode member 55 are made of SUS material, the contact pressure is preferably 0.5 N or more in order to reduce the conduction resistance at the contact portion K of each other. Further, since the inclined portion 54a2 can be elastically displaced in the axial direction of the developing roller 41 at the contact portion K with the outer side portion 55b of the developing side electrode member 55, it is assumed that the developing unit U2 with respect to the photosensitive unit U1 is temporarily moved. Even if the assembly position is displaced in the axial direction of the developing roller 41, the inclined portion 54a2 can be displaced following the displacement, and the contact state can be maintained satisfactorily.

  As described above, in the present embodiment, the photosensitive side electrode member 54 is configured by a plate spring that can be elastically deformed. On the contrary, as shown in FIG. 13, the development side electrode member 55 is configured by a plate spring. May be. In this case, since the developing-side electrode member 55 can be elastically deformed in the axial direction of the developing roller 41, even if the assembly position of the developing unit U2 with respect to the photosensitive unit U1 is shifted in the axial direction of the developing roller 41, the shift On the other hand, the development side electrode member 55 can follow and be displaced, and it is possible to maintain a good contact state. Further, both the developing side electrode member 55 and the photosensitive side electrode member 54 may be configured to be elastically deformable in the axial direction of the developing roller 41. When at least one of the photosensitive-side electrode member 54 and the development-side electrode member 55 is configured by a leaf spring, the contact surface of the leaf spring is formed in a curved surface so as to avoid the influence of edge burrs and the like, and the frictional force due to contact is reduced Can be reduced.

  Further, as shown in FIG. 14, the photosensitive-side electrode member 54 may be constituted by an electrode member in which a conductor 54e made of metal or the like is provided at the tip of a coil spring 54d instead of the leaf spring. In this case, when the developing unit U2 is assembled, the developing-side electrode member 55 comes into contact with the conductor 54e and moves outward to compress the coil spring 54d. Due to the restoring force of the compressed coil spring 54d, the conductor 54e contacts the developing-side electrode member 55 with a predetermined contact pressure. Further, in this case, by making the contact surface of the conductor 54e curved, the frictional force due to the contact can be reduced as described above. Although not shown, contrary to the example shown in FIG. 14, the development-side electrode member 55 may be composed of an electrode member made up of a coil spring and a conductor provided at the tip thereof.

  As described above, in the configuration of the present embodiment, since the electrode members 54 and 55 are in contact with each other when the photoreceptor unit U1 and the developing unit U2 are assembled, the frictional resistance due to this contact is the longitudinal length of each unit U1 and U2. Occurs on one side of the direction. If the balance of the urging force for urging the developing unit U2 with respect to the photosensitive unit U1 is lost due to the influence of the frictional resistance, the developing roller 41 is aimed at the target position or the target contact pressure with respect to the photosensitive member 2. There is a possibility that the contact cannot be made.

20 and 21 are diagrams showing a comparative example having a configuration different from that of the present embodiment.
In the comparative example shown in FIG. 20, the contact portion K between the electrode members 54 and 55 is located further below the lower coil spring 53. When the contact portion K is disposed at such a position, the moments generated by the urging forces F2 and F3 of the coil springs 52 and 53 are generated counterclockwise in the drawing with the contact portion K as the center. As a result, on the counter driving side, the developing unit U2 is held in a posture rotated counterclockwise with respect to the correct posture indicated by a two-dot chain line in the figure, and the developing roller 41 is displaced or inclined with respect to the target contact position. Or

  On the other hand, as shown in FIG. 21, when the contact portion K is located further above the upper coil spring 52, the moment due to the urging forces F2, F3 of the coil springs 52, 53 around the contact portion K is Both occur clockwise in the figure. Accordingly, in this case, the developing unit U2 is held in a clockwise rotation position on the counter-driving side, and the developing roller 41 is displaced or inclined with respect to the target contact position.

  When the developing roller 41 is displaced or tilted with respect to the target contact position as in the examples shown in FIGS. 20 and 21, a horizontal band-like abnormal image may be output for each rotation period of the developing roller 41. is there. Further, when the developing unit U2 itself is twisted due to the influence of the frictional force due to the contact portion K, the end of the developing roller 41 cannot contact the photoreceptor 2, and a white-out image is generated or the developing roller 41 is In some cases, uneven wear causes vertical band-like density unevenness.

  Therefore, in the present embodiment, the following configuration is provided so that the balance of the urging force that urges the developing unit U2 by the frictional resistance between the electrode members 54 and 55 is not lost.

  Specifically, in the present embodiment, as shown in FIG. 15, when viewed from the axial direction of the developing roller 41, the contact portion K between the developing side electrode member 55 and the photosensitive side electrode member 54 is provided at the top. It is configured to be positioned between one counter driving side coil spring 52 and a second counter driving side coil spring 53 provided below.

  In this way, by positioning the contact portion K between the upper coil spring 52 and the lower coil spring 53, the attachment of the two coil springs 52, 53 centering on the contact portion K as shown in FIG. Moments by the forces F2 and F3 act in opposite directions. In this case, the moment due to the biasing force F2 of the upper coil spring 52 is generated counterclockwise, and the moment due to the biasing force F3 of the lower coil spring 53 is generated clockwise. As described above, in this embodiment, the moments generated by the urging forces F2 and F3 of the two coil springs 52 and 53 are opposite to each other, so that the rotational forces due to the two moments cancel each other and are reduced. As a result, the developing unit U2 can be held in a correct posture, and the developing roller 41 can be brought into contact with the photoreceptor 2 with a target contact position and contact pressure.

  More preferably, the photosensitive-side electrode member 54 and the developing-side electrode member 55 are arranged so that moments due to the urging forces F2 and F3 of the coil springs 52 and 53 when the contact portion K is the center are balanced with each other. Is good. As a result, the rotational force due to both moments is completely cancelled, so that the rotational force acting on the developing unit U2 is eliminated, the posture of the developing unit U2 is further stabilized, and the developing roller 41 is more reliably set to the target contact position and It is possible to make contact with the contact pressure.

  In particular, in this embodiment, in order to stabilize the posture of the developing unit U2, as shown in FIG. 16, the two coil springs 52 and 53 on the non-driving side are respectively connected to the photosensitive member 2 and the developing roller 41 that are in contact with each other. They are arranged on opposite sides of a straight line L passing through the rotation centers O1 and O2. In this embodiment, in order to reduce the influence of the frictional resistance at the contact portion K, the photosensitive side electrode member 54 and the development side electrode member 55 are disposed so that the contact portion K exists on the straight line L. doing.

  More preferably, as shown in FIG. 17, the contact portion K is on a straight line L passing through the rotation centers O1 and O2 of the photosensitive member 2 and the developing roller 41 in contact with each other, and The photosensitive side electrode member 54 and the developing side electrode member 55 are preferably disposed so as to exist on or near the axial extension line. In this case, the influence of the frictional resistance in the contact portion K can be further reduced, and the developing unit U2 can be brought into contact with the correct posture.

  Further, in order to reduce the frictional force at the contact portion K, a conductive lubricant may be applied to the contact portion K as shown in FIG. Further, as shown in FIG. 19, it is also effective to interpose a conductive carbon terminal in the contact portion K. When the conductive carbon terminal is interposed, the contact pressure between the photosensitive side electrode member 54 and the development side electrode member 55 can be set low, and as a result, the frictional force at the contact portion K can be reduced. it can.

  As described above, according to the present invention, even in the configuration in which the electrode member (development side electrode member 55) is provided on one side of the development unit, the electrode member and the power source side electrode member (photosensitive side electrode member 54) Since the influence of the frictional force at the contact portion can be reduced, the developing unit can be held in the correct posture. As a result, the developing roller can be brought into contact with the photosensitive member at a target position and contact pressure, so that an abnormal image can be prevented from being generated.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. In the above-described embodiment, the case where the present invention is applied to the configuration in which the developing roller is brought into contact with the photosensitive member, that is, the developing device using the one-component developer has been described. However, the present invention is not limited to this. . The present invention can also be applied to a configuration in which the developing roller is opposed to the photosensitive member via a predetermined gap, that is, a developing device using a two-component developer. In this case, by applying the present invention, the influence of the frictional force at the contact portion between the electrode members can be reduced as described above, so the developing roller is held at the target gap with respect to the photoreceptor. It is possible to prevent the occurrence of abnormal images.

  In the above-described embodiment, the developing-side power-supplied member that is fed by the developing-side electrode member is the developing roller. However, the configuration of the present invention is similarly applied to a conduction path that feeds power to other members such as a regulation blade. Is applicable.

1 (1Y, 1M, 1C, 1Bk) Process unit 2 Photoconductor 4 Developing device 40a Side wall 40b Side wall 40d Rotating shaft 40f Rotating moving shaft 41 Developing roller (developer carrier)
50a Support wall 50b Support wall 50c Hole 50e Groove 51 Drive side coil spring (biasing member)
52 1st counter drive side coil spring (urging member)
53 Second counter driving side coil spring (urging member)
54 Photosensitive side electrode member (Power source side electrode member)
55 Development side electrode member F2 Biasing force of first counter driving side coil spring F3 Biasing force of second counter driving side coil spring K contact portion L Straight line passing through each rotation center of photosensitive member and developing roller O1 Rotation center of photosensitive member O2 Development roller rotation center

JP 2013-20233 A

Claims (10)

A developer carrier for supplying a developer to the surface of the photoreceptor;
A biasing member that biases the developer carrying member toward the photosensitive member;
In a developing device comprising a developing-side electrode member that contacts a power-supply-side electrode member on one end side in the axial direction of the developer carrier and feeds power to the developing-side power-supplied member
Two urging members are provided on the side where the development-side electrode member is provided,
A development characterized in that a contact portion of the developing-side electrode member with respect to the power-supply-side electrode member is positioned between the two urging members when viewed from the axial direction of the developer carrier. apparatus.   The development-side electrode member is disposed so that moments due to the urging forces of the two urging members when the contact portion of the development-side electrode member with the electrode member on the power source side is centered are balanced with each other. 2. The developing device according to 1.   The development-side electrode member so that the contact portion of the development-side electrode member with the electrode member on the power-supply side exists on a straight line passing through the respective rotation centers of the photosensitive member and the developer-carrying member in contact with each other. The developing device according to claim 1, wherein a developing device is provided.   The development according to claim 3, wherein the development-side electrode member is disposed so that a contact portion of the development-side electrode member with respect to the power-source-side electrode member is present on or near the axial extension line of the developer carrier. apparatus. A pair of side wall portions that support both axial ends of the developer carrying member are configured to be assembled to a pair of support walls that support both axial ends of the photosensitive member,
The development side electrode member is provided on one of the side wall portions,
5. The developing device according to claim 1, wherein an electrode member on the power supply side is provided on the support wall on the same side as the one side wall portion. 6. The one side wall portion is configured to be assembled with respect to one of the support walls via a groove and a rotational movement shaft that is movable and rotatable in the groove,
The developing device according to claim 5, wherein the other side wall is configured to be assembled to the other of the support walls via a hole and a rotation shaft that is rotatably inserted into the hole.   7. The apparatus according to claim 1, wherein the two urging members are disposed on opposite sides of a straight line passing through the rotation centers of the photosensitive member and the developer carrying member in contact with each other. The developing device according to item.   8. The device according to claim 1, wherein at least one of the developing-side electrode member and the power-supply-side electrode member is configured to be elastically displaced in the axial direction of the developer carrier at the contact portion. Development device.   9. A process unit configured to be detachable from an image forming apparatus main body and comprising at least a photosensitive member and the developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1.

Images