JP4858642B2 - Liquid developing device and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming technique such as a printer, a copying machine or a facsimile machine, and more particularly to an image forming technique adopting a wet developing method as a developing method.

  2. Description of the Related Art Conventionally, an image forming apparatus adopting a wet development system has a liquid developer applied to the surface of a developing roller (developer carrying member) with a uniform thickness, and an electrostatic latent image formed on a latent image carrying member. There has been known a configuration in which an image without density unevenness is formed by developing the image. As described above, the following techniques have been conventionally proposed as techniques for uniformly applying the liquid developer to the surface of the developing roller. That is, before applying the liquid developer to the surface of the developing roller, the engraving (groove) portion once formed on the surface of the anilox roller (application roller) regularly and obliquely with respect to the rotation direction of the anilox roller. By carrying the liquid developer on the liquid developer, the amount of the liquid developer is accurately measured. Then, the liquid developer accurately measured by the anilox roller is applied to the developing roller, so that the accurately measured liquid developer is transferred to the developing roller, and the developer having a uniform thickness is transferred to the developing roller. A thin layer can be formed (see, for example, Patent Document 1).

JP 2002-72692 A ([0057] to [0059], FIG. 3)

  By the way, in the above-described conventional apparatus, the liquid developer carried in the groove formed on the coating roller is rotated by rotating the surface of the coating roller while contacting the surface of the developer carrier. It is applied to. Therefore, the following thrust force may be generated on the application roller and the developer carrying member. That is, in the apparatus described in Patent Document 1 described above, grooves are formed regularly and obliquely with respect to the rotation direction on the surface of the application roller, and the application roller and the developer carrier rotate while abutting each other. ing. As a result, a thrust force is generated in the coating roller and the developer carrying member, and the following problems may occur.

  In this type of image forming apparatus, the developer carrier is designed so that play is generated in the thrust direction in consideration of manufacturing errors, assemblability, and the like, and may be movable in the thrust direction. Therefore, when a thrust force is generated in the developer carrier as described above, the developer carrier moves, and the position of the developer carrier relative to the latent image carrier and the application roller in the thrust direction may not be stable. there were. As a result, the developing accuracy for developing the electrostatic latent image on the latent image carrier deteriorates due to the unstable contact position of the developer carrier with respect to the latent image carrier in the thrust direction during the developing operation. There was a case. Further, the contact position of the developer carrier with respect to the application roller in the thrust direction becomes unstable, so that the application pattern of the liquid developer applied to the developer carrier may be disturbed. Such disturbance of the coating pattern causes deterioration in development accuracy.

  In the above description, the problem due to the movement of the developer carrying member in the thrust direction has been described. However, a similar problem may occur in the application roller. That is, the application roller may be movable in the thrust direction in consideration of manufacturing errors and the like. Therefore, the thrust force generated as described above is applied to the application roller, and the position of the application roller with respect to the developer carrier may not be stable. As a result, the coating pattern applied to the developer carrying member is disturbed and the development accuracy is deteriorated.

This aspect of the invention, in the composition for applying the liquid developer to the developer carrying member by coating roller having diagonal grooves, to prevent movement of the coating roller against a developer carrying member in the developing operation is to improve the development precision and purpose.

In order to achieve the above object, the liquid developing device according to the present invention has a developer carrying member and a groove provided obliquely with respect to the rotation direction, and development is performed while carrying the liquid developer in the groove. The application roller that conveys the liquid developer to the developer carrying member by transporting it to a position in contact with the agent carrying member, and the application roller engaging position in the thrust direction perpendicular or almost perpendicular to the rotation direction of the application roller. A coating roller positioning portion; and a coating roller biasing member that biases the coating roller in a direction in which the coating roller moves due to a thrust force generated by rotating the coating roller and the developer carrying member in contact with each other. It is characterized by having. In order to achieve the above object, an image forming apparatus according to the present invention comprises a latent image carrier, a developer carrier that contacts the latent image carrier and develops a liquid developer, and rotates in the first direction. In addition, a groove provided obliquely with respect to the first direction is provided, and the liquid developer is transported to a position in contact with the developer carrying body while carrying the liquid developer in the groove, and the developer is carried on the liquid developer. The application roller applied to the body, the application roller positioning portion locked at the application roller locking position in the thrust direction orthogonal or nearly orthogonal to the rotation direction of the application roller, and the application roller and the developer carrier are in contact with each other An application roller urging member that urges the application roller in a direction in which the application roller moves due to a thrust force generated by rotation is provided. With this configuration, for example, even when the application roller is movable in the thrust direction in consideration of manufacturing errors and the like, the thrust of the application roller and the urging force of the urging member for the application roller during the developing operation These two forces can be moved to a predetermined application roller locking position in the thrust direction in a short time, and can be locked by the application roller positioning portion. Therefore, it is possible to prevent the development roller from moving due to the movement of the application roller with respect to the developer carrying member during the development operation, thereby improving the development accuracy.

  Further, it is desirable that the application roller urging member has an urging force larger than a static frictional force acting between the developer carrier and the application roller. With such a configuration, the application roller can be moved to the application roller locking position only by the urging force of the application roller urging member and locked by the application roller positioning portion. Therefore, the application roller is positioned at the application roller locking position when the apparatus is assembled. Therefore, when a thrust force is generated on the application roller during the developing operation, the application roller is already locked by the application roller positioning portion at a predetermined application roller locking position, and by the thrust force generated on the application roller, The application roller does not move further. Also, the application roller is firmly locked by the application roller positioning portion at a predetermined application roller locking position in the thrust direction by the application of the two forces of the urging force and thrust force of the application roller urging member. Has been. Therefore, during the developing operation, for example, even if the apparatus is tilted due to vibration, the application roller can be reliably prevented from moving from a predetermined application roller locking position. Also, since the application roller can be reliably locked at a predetermined application roller locking position immediately after the start of the development operation, the movement of the application roller relative to the developer carrier during the development operation can be prevented more efficiently. The development accuracy can be improved.

  The biasing member may be a bias application contact. With such a configuration, it is possible to use both the contact point for applying a bias to the application roller and the developer carrying member and the urging member, so that the number of parts can be reduced and the device configuration can be simplified. Further, the urging member can be constituted by a spring or the like, for example.

  In addition, the application roller is an anilox roller having a groove formed on the surface thereof, and the liquid developer is conveyed by carrying the liquid developer in the groove, or the application roller is a wire It can be set as the structure which is a bar. With such a configuration, the liquid developer measured in a certain amount can be applied to the developer carrier by carrying the liquid developer in the groove of the anilox roller or the recess between the wires of the wire bar. it can. Therefore, it is possible to apply the liquid developer to the developer carrying member accurately and uniformly. In this way, the developer carrying body uniformly coated with the liquid developer comes into contact with the latent image carrying body and develops the electrostatic latent image on the latent image carrying body. Development accuracy can be improved.

  In addition, when the coating roller is constituted by a wire bar, the surface roughness of the wire bar is relatively small, so that the static frictional force at the contact portion between the wire bar and the developer carrier can be reduced. Accordingly, the wire bar and the developer carrying member can be relatively moved in the thrust direction while being in contact with each other. Therefore, the wire bar and the developer carrier can be reliably moved in the thrust direction while being brought into contact with each other, and can be moved to a predetermined locking position in the thrust direction in a short time.

1 is a diagram illustrating an internal configuration of a printer that is a first embodiment of the present invention. FIG. The principal part enlarged view of FIG. FIG. 2 is a block diagram showing an electrical configuration of the printer. The perspective conceptual diagram which shows an anilox roller. FIG. 3 is a schematic diagram of a developing unit viewed from the direction of arrow A in FIG. 2. The schematic diagram of the image development part seen from the direction of the arrow A of FIG. 2 in 2nd Embodiment. The schematic diagram of the image development part seen from the direction of arrow A of FIG. 2 in 3rd Embodiment. The schematic diagram of the image development part seen from the direction of the arrow A of FIG. 2 in 4th Embodiment. The schematic diagram of the image development part seen from the direction of the arrow A of FIG. 2 in 5th Embodiment. FIG. 10 is a schematic diagram of a developing unit viewed from the direction of arrow A in FIG. 2 in a sixth embodiment. The schematic diagram which shows the wire bar in 7th Embodiment. FIG. 3 is a schematic diagram of a developing unit viewed from the direction of arrow A in FIG. 2.

<First Embodiment>
FIG. 1 is a diagram showing an internal configuration of a printer that is a first embodiment of an image forming apparatus according to the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a block diagram showing an electrical configuration of the printer. is there. This image forming apparatus is a so-called tandem type color printer, and the four-color photoconductors of yellow (Y), magenta (M), cyan (C), and black (K) are used as the “latent image carrier” of the present invention. 11Y, 11M, 11C, and 11K are arranged in the apparatus main body 2 side by side. This printer employs a wet development system to form a full-color image by superimposing the toner images on the photoconductors 11Y, 11M, 11C, and 11K, or a monochrome image using only a black (K) toner image. Is formed. In this printer, when a print command signal including an image signal is given to the main control unit 100 from an external device such as a host computer, the engine control unit 110 causes each part of the engine unit 1 to respond to the control signal from the main control unit 100. The image corresponding to the image signal is printed out on the recording medium 4 such as transfer paper, copy paper, and OHP paper conveyed from the paper feed cassette 3 disposed in the lower part of the apparatus main body 2.

  In the engine unit 1, a charging unit corresponding to each of the four photoconductors 11 </ b> Y, 11 </ b> M, 11 </ b> C, and 11 </ b> K arranged in parallel along the circumferential direction 47 of the intermediate transfer belt 41 that is a component of the transfer unit 40. 12, an exposure unit 20, a developing unit 30 (30Y, 30M, 30C, 30K) and a photoconductor cleaning unit 14 are provided. Each of the developing units 30Y, 30M, 30C, and 30K includes a tank 33 (33Y, 33M, 33C, and 33K) that stores a developer 32 in which each color toner is dispersed. Note that the configurations of the charging unit 12, the exposure unit 20, the developing unit 30, and the photosensitive member cleaning unit 14 are the same for all toner colors. Therefore, here, the configuration relating to yellow will be described, and the other toner colors will be denoted by the same or corresponding symbols, and description thereof will be omitted.

  As shown in FIG. 2, the photoreceptor 11Y is rotatably provided in the direction of the arrow (clockwise direction in the figure), and its diameter is about 40 mm. A charging unit 12, a developing roller 31, a charge eliminating unit (not shown), and a photoconductor cleaning unit 14 are disposed around the photoconductor 11Y along the rotation direction. Further, a surface area between the charging unit 12 and the developing position 16 is an irradiation area of the light beam 21 from the exposure unit 20. The charging unit 12 is applied with a charging bias from the charging bias generator 111 to uniformly charge the outer peripheral surface of the photoconductor 11Y to a predetermined surface potential Vd (for example, Vd = DC + 600 V), and functions as a charging unit. Have.

  A light beam 21 formed by a laser, for example, is irradiated from the exposure unit 20 toward the outer peripheral surface of the photoreceptor 11Y uniformly charged by the charging unit 12. The exposure unit 20 exposes the photoconductor 11Y by the light beam 21 in accordance with a control command given from the exposure control unit 112, and forms a yellow electrostatic latent image corresponding to the image signal on the photoconductor 11Y. Thus, it has a function as an exposure means. For example, when a print command signal including an image signal is given from an external device such as a host computer to the CPU 101 of the main control unit 100 via the interface 102, the CPU 113 controls the exposure control unit in response to a command from the CPU 101 of the main control unit 100. A control signal corresponding to the image signal is output to 112 at a predetermined timing. Then, in response to a control command from the exposure control unit 112, the light beam 21 is irradiated from the exposure unit 20 to the photoconductor 11Y, and an electrostatic latent image for yellow corresponding to the image signal is formed on the photoconductor 11Y. . When a patch image is formed as necessary, a control signal corresponding to a patch image signal of a predetermined pattern (for example, a solid image, a fine line image, a white line image, etc.) set in advance is controlled from the CPU 113. A yellow electrostatic latent image corresponding to the pattern is given to the portion 112 and formed on the photoconductor 11Y.

  The yellow electrostatic latent image formed in this way is visualized by yellow toner supplied from the developing roller 31 of the developing unit 30Y (developing step). The yellow toner image formed on the photoreceptor 11Y is conveyed to the primary transfer position 42Y that faces the primary transfer roller 53Y as the photoreceptor 11Y rotates. The primary transfer roller 53Y is disposed so as to sandwich the intermediate transfer belt 41 with the photoreceptor 11Y. The intermediate transfer belt 41 is stretched around a plurality of rollers 43a to 45. The intermediate transfer belt 41 and the photosensitive member 11Y are moved in a direction 47 (counterclockwise in FIG. 1) that is driven by the driving motor (not shown). Drive around at the same peripheral speed. When a primary transfer bias (for example, DC-400 V) is applied from the transfer bias generator 115, the yellow toner image on the photoreceptor 11Y is primarily transferred to the intermediate transfer belt 41 at the primary transfer position 42Y ( Transfer process).

  On the other hand, the residual charge on the photoconductor 11Y after the primary transfer is removed by a charge eliminating unit such as an LED, and the residual developer is removed by the photoconductor cleaning unit. The photoconductor cleaning unit 14 includes a rubber photoconductor cleaning blade 141 that is in contact with the surface of the photoconductor 11Y. After the toner image is primarily transferred to the intermediate transfer belt 41, the photoconductor cleaning unit 14 is placed on the photoconductor 11Y. The remaining developer 32 can be scraped off and removed by the photoreceptor cleaning blade 141. The configuration and operation of the developing unit 30Y will be described in detail later.

  The other toner colors are configured in the same manner as yellow (Y), and a toner image corresponding to the image signal is formed. The yellow (Y), magenta (M), cyan (C), and black (K) toner images formed on the photoconductors 11Y, 11M, 11C, and 11K are primary transfer rollers 53Y, 53M, and 53C. , 53K and primary transfer positions 42Y, 42M, 42C, and 42K, respectively, are superimposed on the surface of the intermediate transfer belt 41 to form a full-color toner image.

  The toner image formed on the intermediate transfer belt 41 is conveyed to a secondary transfer position 49 sandwiched between rollers 45 and 48 as the intermediate transfer belt 41 rotates. On the other hand, the recording medium 4 accommodated in the paper feed cassette 3 (FIG. 1) is conveyed to the secondary transfer position 49 by a conveyance unit 70 described later in synchronization with the conveyance of the primary transfer toner image. The roller 48 rotates in the direction of following the intermediate transfer belt 41 (clockwise in FIG. 1) at the same peripheral speed as the intermediate transfer belt 41, and a secondary transfer bias is applied from the transfer bias generator 115. Then, the toner image on the intermediate transfer belt 41 is secondarily transferred to the recording medium 4. As the roller 48, for example, a rubber having a rubber hardness of about 50 degrees in JIS-A and having a diameter of about 25 mm can be used. In this embodiment, since roller transfer is adopted, the transfer condition can be set by constant voltage control, or the transfer condition can be set by constant current control. Further, instead of roller transfer, transfer may be performed by corona discharge. In this case, transfer conditions can be set by controlling the output of corona discharge. The residual developer on the intermediate transfer belt 41 after the secondary transfer is removed by the cleaning blade 51.

  The recording medium 4 onto which the toner image has been secondarily transferred as described above is conveyed along a predetermined conveying path 5 (the chain line in FIG. 1), and the toner image is fixed to the recording medium 4 by the fixing unit 60. Then, it is discharged to a discharge tray provided at the upper part of the apparatus main body 2. The fixing unit 60 includes a heating roller 61 incorporating a heater 61 h and a pressure roller 62 that contacts the heating roller 61. The heater controller 116 controls the operation of the heater 61h, so that the fixing temperature in the fixing unit 60 can be adjusted to an arbitrary temperature.

  In the image forming apparatus according to this embodiment, a transport unit 70 for transporting the recording medium 4 along a predetermined transport path 5 is provided. As shown in FIG. 1, the transport unit 70 is provided with a paper feed roller 71 corresponding to the paper feed cassette 3, and the recording medium 4 accommodated in the paper feed cassette 3 is received by the paper feed roller 71. Each sheet is taken out and conveyed to the feed roller 72. The feed roller 72 transports the recording medium 4 to the gate roller 73 and temporarily stands by at the gate roller position. Then, as described above, the gate roller 73 is driven at the timing corresponding to the secondary transfer operation, and the recording medium 4 is sent to the secondary transfer position 49. Further, on the discharge tray side, a pre-discharge roller 74, a discharge roller 75, and a reverse roller 76 are provided, and the secondary transferred recording medium 4 passes through the fixing unit 60, the pre-discharge roller 74, and the discharge roller 75. It is conveyed to the discharge tray side.

  Here, in order to perform double-sided printing, it is necessary to reverse the recording medium 4 and transport it to the gate roller 73 again, so that the discharge roller 75 can rotate forward and backward. That is, when the recording medium 4 is directly discharged to the discharge tray, the recording medium 4 continues to rotate forward and is completely conveyed to the discharge tray. On the other hand, when reversing and refeeding, when the rear end of the recording medium 4 reaches a predetermined position between the pre-discharge roller 74 and the discharge roller 75, the discharge roller 75 rotates reversely to reverse the recording medium 4. Feed into roller 76. As a result, the recording medium 4 is conveyed to the refeed intermediate roller 77 along the reverse path 5a. Then, the re-feed intermediate roller 77 and the pre-re-feed gate roller 78 transport the recording medium 4 to the gate roller 73 and temporarily stand by at the gate roller position. In this way, reverse refeeding of the recording medium 4 is performed. At this time, the surface of the recording medium 4 to which the image is transferred by contacting the intermediate transfer belt 41 at the secondary transfer position 49 is the surface opposite to the surface on which the image has been transferred first. In this way, images can be formed on both sides of the recording medium 4. Further, when the secondary transfer is performed on the opposite surface, the surface on which the image has been transferred first comes into contact with the roller 48. At this time, the toner not completely fixed on the recording medium 4 is applied to the roller 48. May adhere. Thus, the toner adhering to the roller 48 is removed by the cleaning blade 52.

  In FIG. 3, the main control unit 100 includes an image memory 103 for storing an image signal given from an external device via the interface 102, and the CPU 101 prints a print command including the image signal from the external device. When the signal is received via the interface 102, it is converted into job data in a format suitable for the operation instruction of the engine unit 1 and sent to the engine control unit 110.

  The memory 117 of the engine control unit 110 includes a ROM that stores a control program of the CPU 113 including preset fixed data, a RAM that temporarily stores control data of the engine unit 1 and a calculation result by the CPU 113, and the like. Become. The CPU 113 stores data relating to the image signal sent from the external device via the CPU 101 in the memory 117.

  Next, the configuration and operation of the developing unit 30Y will be described in detail with reference to FIGS. FIG. 4 is a conceptual perspective view of an anilox roller having grooves formed on the surface, and FIG. 5 is a schematic view of the developing unit viewed from the direction of arrow A in FIG. The configurations of the developing units 30M, 30C, and 30K are the same as the configuration of the developing unit 30Y, and the same components are denoted by the same or corresponding reference numerals, and the description thereof is omitted.

  The developing unit 30Y includes, in addition to the developing roller 31 (corresponding to the “developer carrier” of the present invention), a tank 33Y that stores a developer 32 in which yellow toner is dispersed, and a developer that is stored in the tank 33Y. A stirring roller 37 that stirs 32, a coating roller 34 that pumps out the developer 32 and applies it to the developing roller 31, a regulation blade 35 that uniformly regulates the thickness of the developer layer on the coating roller 34, and photosensitive And a developing roller cleaning section 36 for removing the developer remaining on the developing roller 31 after supplying the toner to the body 11Y. The developing roller 31 rotates at a peripheral speed substantially equal to that of the photoconductor 11Y in a direction D1 (counterclockwise in FIG. 2) that follows the photoconductor 11Y. The application roller 34 rotates at a peripheral speed substantially equal to that of the developing roller 31 in a direction D2 (clockwise in FIG. 2, corresponding to the “first direction” of the present invention) driven by the developing roller 31.

  In this embodiment, the developer 32 (corresponding to the “liquid developer” of the present invention) is applied to a color pigment having an average particle size of about 0.1 to 5 μm, an adhesive such as an epoxy resin to which the color pigment is adhered, and a toner. A toner composed of a charge control agent that gives a predetermined charge, a dispersant that uniformly disperses the color pigment, and the like is dispersed in a liquid carrier. In this embodiment, for example, a silicone oil such as polydimethylsiloxane oil is used as the liquid carrier, and the toner concentration is 5 to 40% by weight. 2% by weight). The type of the liquid carrier is not limited to silicone oil, and the viscosity of the developer 32 is determined by the liquid carrier to be used, each material constituting the toner, the toner concentration, etc. In this embodiment, For example, the viscosity is 100 to 10,000 mPa · s.

  In this embodiment, the distance between the photoconductor 11Y and the developing roller 31 (development gap = thickness of the developer layer) is set to, for example, 5 to 40 μm, and the development nip distance (the developer layer is the photoconductor 11Y and the developing roller 31). In this embodiment, the distance in the circumferential direction in contact with both is set to 5 mm, for example. In the case of the low-concentration developer described above, a development gap of 100 to 200 μm is required to increase the amount of toner, and in this embodiment using a high-concentration developer, the development gap can be shortened. Accordingly, the moving distance of the toner moving in the developer by electrophoresis is shortened, and a higher electric field is generated even when the same developing bias is applied, so that the developing efficiency can be improved and the developing can be performed at a high speed. It will be possible.

  The agitating roller 37 draws up the developer 32 stored in the tank 33Y and conveys it to the application roller 34. The lower portion of the stirring roller 37 is immersed in the developer 32 stored in the tank 33Y, and is spaced apart from the coating roller 34 with a width of about 1 mm. Further, the stirring roller 37 is rotatable around its central axis, and the central axis is below the rotation central axis of the application roller 34. Further, the stirring roller 37 rotates in the same direction as the rotation direction of the application roller 34 (clockwise in FIG. 5). The stirring roller 37 has a function of pumping up the developer 32 stored in the tank 33Y and transporting it to the application roller 34, and also has a function of stirring the developer 32 in order to maintain it in an appropriate state. ing. As such a stirring roller, for example, a roller made of metal such as iron and having a diameter of about 20 mm can be used.

  The coating roller 34 supplies the developing solution 32 conveyed from the tank 33Y by the stirring roller 37 to the developing roller 31 at the coating position 17. This application roller 34 is called a so-called anilox roller in which grooves 34a are formed in a uniform and spiral shape on the surface of a metallic roller such as iron and nickel plating is applied, as shown in FIG. Its diameter is about 25 mm. In the present embodiment, as shown in FIG. 4, a plurality of grooves 34 a are formed obliquely with respect to the rotation direction D 2 of the application roller 34. The application roller 34 is provided with a roller drive motor 340 electrically connected to the roller drive unit 118 (FIG. 3), and the roller drive motor 340 rotates in accordance with a control signal from the roller drive unit 118. As the roller drive motor 340 rotates, the application roller 34 rotates in the direction of the arrow D2. As described above, the application roller 34 contacts the developing solution 32 while rotating clockwise, thereby supporting the developing solution 32 in the groove 34 a and conveying the supported developing solution 32 to the developing roller 31. Accordingly, the application roller 34 can apply the developer 32 to the developing roller 31 with a width in the X direction in which the groove 34a is formed.

  Further, the surface of the application roller 34 is in pressure contact with a later-described elastic layer of the development roller 31 in order to appropriately apply the developer 32 on the application roller 34 to the development roller 31. Further, the application roller 34 can rotate around its central axis, and the central axis is below the rotation central axis of the developing roller 31. The application roller 34 rotates in a direction (clockwise in FIG. 2) opposite to the rotation direction of the developing roller 31 (counterclockwise in FIG. 2).

  The regulating blade 35 contacts the surface of the application roller 34 along the thrust direction of the application roller 34 on the upstream side of the application position 17 in the rotation direction D2 of the application roller 34, and the developer 32 on the application roller 34. Regulate the amount of That is, the regulation blade 35 plays a role of scraping off the excess developer 32 on the application roller 34 and measuring the amount of developer 32 on the application roller 34 supplied to the development roller 31. The restriction blade 35 is made of urethane rubber as an elastic body, and is supported by a restriction blade support member 351 made of metal such as iron. In this embodiment, the rubber hardness of the regulating blade 35 is approximately 77 degrees according to JIS-A, and the regulating blade 35 is arranged so that the tip thereof faces the downstream side in the rotation direction of the application roller 34. , So-called trail regulation.

The developing roller 31 carries the developer 32 and conveys it to the developing position 16 facing the photoreceptor 11Y in order to develop the electrostatic latent image carried on the photoreceptor 11Y by the developer 32. The developing roller 31 is provided with an elastic body layer as an example of an elastic portion having conductivity on the outer peripheral portion of an inner core made of metal such as iron, and has a diameter of about 20 mm. The elastic body layer has a two-layer structure. As the inner layer, urethane rubber having a rubber hardness of about 30 degrees JIS-A and a thickness of about 5 mm is used, and as the surface layer (outer layer), the rubber hardness is JIS. A urethane rubber having a thickness of about 30 μm at about 85 ° A is provided. The developing roller 31 is in pressure contact with the coating roller 34 and the photoreceptor 11Y in a state of being elastically deformed with the surface layer serving as a pressure contact portion.

  Further, the developing roller 31 can rotate around its central axis, and the central axis is below the rotational central axis of the photoconductor 11Y. The developing roller 31 is provided with a roller driving motor 310 electrically connected to the roller driving unit 118, and the roller driving motor 310 rotates in accordance with a control signal from the roller driving unit 118. As the roller drive motor 310 rotates, the developing roller 31 rotates in a direction D1 (counterclockwise in FIG. 2) opposite to the rotation direction of the photoconductor 11Y. When developing the electrostatic latent image formed on the photoconductor 11Y, an electric field is formed between the developing roller 31 and the photoconductor 11Y.

  The developing roller cleaning unit 36 is a rubber developing roller cleaning blade that is in contact with the surface of the developing roller 31 along the thrust direction of the developing roller 31 on the downstream side of the developing position in the rotation direction D1 of the developing roller 31. 361. Then, after developing at the developing position 16, the developing solution 32 remaining on the developing roller 31 is scraped off by the developing roller cleaning blade 361 to be removed.

  In the developing unit 30 </ b> Y configured as described above, the stirring roller 37 rotates around its central axis, thereby pumping up the developer 32 stored in the tank 33 </ b> Y and transporting it to the application roller 34. The developer 32 conveyed to the application roller 34 reaches the contact position of the regulation blade 35 by the rotation of the application roller 34. Then, when passing through the corresponding contact position, the surplus portion of the developing solution 32 is scraped off by the regulating blade 35 and the amount of the developing solution 32 supplied to the developing roller 31 is measured. That is, as described above, the application roller 34 is provided with the groove 34a. Therefore, the regulating blade 35 that contacts the application roller 34 develops from the application roller 34 while leaving the developer 32 carried in the groove 34a. The liquid 32 is scraped off. In addition, since the dimension of the groove 34 a is determined so that the amount of the developer 32 supplied to the developing roller 31 is an appropriate amount, when the regulating blade 35 scrapes off the developer 32 on the application roller 34. In this case, the developer 32 measured in an appropriate amount by the groove 34a remains in the groove 34a.

  In this manner, the developer 32 stored in the tank 33Y is pumped out by the application roller 34, the amount of the developer 32 on the application roller 34 is uniformly regulated by the regulation blade 35, and the uniform developer 32 is It is applied to the surface of the developing roller 31 at the applying position 17 and is conveyed to the developing position 16 facing the photoreceptor 11Y as the developing roller 31 rotates. For example, the toner in the developer 32 is positively charged by the action of a charge control agent or the like. Then, the developing solution 32 carried on the developing roller 31 at the developing position 16 is supplied from the developing roller 31 and adheres to the photosensitive member 11Y, and the developing bias Vb (applied to the developing roller 31 from the developing bias generator 114). For example, Vb = DC + 400V), the yellow toner moves from the developing roller 31 to the photoreceptor 11Y, and the yellow electrostatic latent image is visualized. Further, the developer remaining on the developing roller 31 without adhering to the photoconductor 11Y is scraped off by the developing roller cleaning blade 361.

  As described above, the yellow toner image formed on the photoreceptor 11Y in this way is primarily transferred to the intermediate transfer belt 41 at the primary transfer position 42Y, and remains on the photoreceptor 11Y after the primary transfer is completed. The developing solution 32 is removed by the photoconductor cleaning unit 14.

  Next, the configuration and operation of the developing roller 31 and the application roller 34 will be described in more detail with reference to FIG. On the surface of the coating roller 34, as described above, a plurality of grooves 34a provided obliquely with respect to the rotation direction D2 of the coating roller 34 are formed. Accordingly, when the application roller 34 and the developing roller 31 rotate while being in contact with each other, thrust forces THar and THdr are generated in the application roller 34 and the developing roller 31, respectively. In this embodiment, a bias applying contact 38b that urges the developing roller 31 in the same direction as the side to which the thrust force THdr generated in the developing roller 31 faces (corresponding to the “urging member for developer carrying member” of the present invention). Is supported by the contact support member 381 (see FIG. 5). The bias applying contact 38b is electrically connected to the developing bias generating unit 114, and the developing bias generating unit 114 can apply a developing bias to the developing roller 31 via the bias applying contact 38b. Further, as shown in FIG. 5, the bias applying contact 38b in the present embodiment is constituted by a leaf spring. Further, the biasing force BFdr of the bias applying contact 38b in the present embodiment is a static friction force acting between the developing roller 31 and the photoconductor 11Y, and a static friction acting between the developing roller 31 and the application roller 34. It is configured to be greater than the sum of power.

  The developing roller 31 and the coating roller 34 are rotatably disposed in the tank 33Y by inserting respective rotation shafts through holes provided in the tank 33Y. An E-ring 382b is attached to a predetermined position of the rotation shaft of the developing roller 31 outside the side wall of the tank 33Y on the (−X) side. The E-ring 382b abuts against the side wall of the tank 33Y, so that the developing roller 31 can be locked at a predetermined position (corresponding to the “developer carrier locking position” in the present invention). Thus, the E-ring 382b functions as the “developer-bearing member positioning portion” of the present invention. On the other hand, an E-ring 382a is attached to a predetermined position of the rotation shaft of the application roller 34 outside the side wall of the tank 33Y on the (+ X) side. The application roller 34 can be locked at a predetermined position (corresponding to the “application roller locking position” in the present invention) by the E ring 382a coming into contact with the side wall of the tank 33Y. Thus, the E-ring 382a functions as the “coating roller positioning portion” of the present invention.

  By the way, in the present embodiment, the developing roller 31 is designed so that play is generated in the thrust direction in consideration of manufacturing errors, assemblability, and the like, and is movable in the thrust direction. Therefore, when an external force in the thrust direction is applied to the developing roller 31, it moves. Accordingly, as the developing roller 31 and the coating roller 34 rotate while contacting each other during the developing process and the thrust force THdr is generated, the developing roller 31 tends to move to the side where the thrust force THdr is directed. Therefore, in this embodiment, the biasing contact BFdr is applied to the developing roller 31 by the bias applying contact 38b to prevent the developing roller 31 from moving. The manner in which the developing roller 31 is prevented from moving by applying the biasing force BFdr to the developing roller 31 will be described in detail below.

a) Before rotation The biasing force BFdr applied to the developing roller 31 by the bias applying contact 38b acts between the developing roller 31 and the applying roller 34 and the static frictional force acting between the developing roller 31 and the photoreceptor 11Y. It is larger than the sum of the static frictional force. Therefore, the developing roller 31 can move to the (+ X) side by the biasing force BFdr from the bias applying contact 38b until the E-ring 382b contacts the tank 33Y. The developing roller 31 is locked at a predetermined position by the E ring 382b. In this embodiment, the application roller 34 is also locked at a predetermined position by the E ring 382a (see FIG. 5A).

b) During rotation As the coating roller 34 and the developing roller 31 rotate while contacting, thrust forces THar and THdr are generated in the coating roller 34 and the developing roller 31, respectively. The side to which the thrust force THdr generated in the developing roller 31 faces is the same as the direction of the biasing force BFdr. Therefore, the two forces of the thrust force THdr and the urging force BFdr act on the developing roller 31, whereby the developing roller 31 is more firmly locked by the E ring 382b. At this time, the application roller 34 is also locked by the E-ring 382a and does not move (see FIG. 5B).

c) Immediately after the rotation stops As the application roller 34 and the developing roller 31 stop rotating, the thrust forces THar and THdr generated on the respective rollers disappear (FIG. 5C). However, a biasing force BFdr is applied to the developing roller 31 in the (+ X) direction by the bias applying contact 38b, and the developing roller 31 is locked by the E ring 382b and does not move.

  As described above, in this embodiment, the E-ring 382b (developer carrier positioning portion) that locks the developing roller 31 at a predetermined position (developer carrier locking position) in the thrust direction is provided and applied. The bias application contact 38b (biasing member for developer carrying member) is applied in the same direction as the direction in which the development roller 31 tries to move by the thrust force THdr generated by rotating the roller 34 and the development roller 31 in contact with each other. The developing roller 31 is urged. The biasing force BFdr of the bias applying contact 38b is the sum of the static friction force acting between the developing roller 31 and the photoconductor 11Y and the static friction force acting between the developing roller 31 and the application roller 34. It is comprised so that it may become larger. Therefore, for example, as in the present embodiment, the developing roller 31 is designed so that play is generated in the thrust direction in consideration of manufacturing errors, assembling properties, etc., and even when it is movable in the thrust direction, The developing roller 31 is moved to a predetermined position (developer carrier engaging position) only by the urging force of the bias applying contact 38b (developer carrier urging member), and the E ring 38b (developer carrier). It can be locked by a positioning part). Therefore, the developing roller 31 is positioned at a predetermined position when the apparatus is assembled. Therefore, when the thrust force THdr is generated on the developing roller 31 during the developing operation, the developing roller 31 is already locked at the predetermined position by the E-ring 382b, and the developing force is generated by the thrust force THdr generated on the developing roller 31. The roller 31 does not move further. Further, the developing roller 31 is firmly locked by the E-ring 382b at a predetermined position in the thrust direction by the application of the two forces of the biasing force BFdr and the thrust force THdr of the bias applying contact 38b. Therefore, during the developing operation, for example, even if the apparatus is tilted due to vibration, it is possible to reliably prevent the developing roller 31 from moving from a predetermined position. Further, since the developing roller 31 can be reliably locked at a predetermined position immediately after the start of the developing operation, the movement of the developing roller 31 relative to the photoreceptor and the application roller 34 during the developing operation can be prevented more efficiently. The development accuracy can be improved.

  Further, the biasing member in the present invention is constituted by a bias applying contact 38b (plate spring). Accordingly, since the contact point for applying a bias to the developing roller 31 and the urging member can be used in common, the number of parts can be reduced, and the apparatus configuration can be simplified.

  The application roller 34 is an anilox roller having a groove formed on the surface thereof, and is configured to convey the developer 32 by carrying the developer 32 in the groove 34a. Therefore, the developer 32 measured in a certain amount can be applied to the developing roller 31 by carrying the developer 32 in the groove 34a of the application roller 34 (anilox roller). Therefore, the developing solution 32 can be applied to the developing roller 31 with high accuracy and uniformity. As described above, the developing roller 31 to which the developing solution 32 is uniformly applied comes into contact with the photosensitive member to develop the electrostatic latent image on the photosensitive member, thereby improving the developing accuracy of the electrostatic latent image. be able to.

<Second Embodiment>
FIG. 6 is a schematic diagram of the developing unit viewed from the direction of arrow A in FIG. 2 in the second embodiment of the image forming apparatus according to the present invention. The second embodiment is greatly different from the first embodiment in that a bias applying contact 38a is provided on the application roller 34 as an application roller urging member of the present invention, and roller drive motors 310 and 340 are provided on the development roller. 31 and the application roller 34 on the (−X) side, and other configurations are the same as those in the first embodiment. Hereinafter, the second embodiment will be described in detail focusing on the differences from the first embodiment. In addition, about the structure and operation | movement same as 1st Embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  On the surface of the coating roller 34, a plurality of grooves 34a provided obliquely with respect to the rotation direction D2 of the coating roller 34 are formed as in the first embodiment. Accordingly, when the application roller 34 and the developing roller 31 rotate while being in contact with each other, thrust forces THar and THdr are generated in the application roller 34 and the developing roller 31, respectively. In this embodiment, a bias application contact 38a that urges the application roller 34 in the same direction as the side to which the thrust force THar generated in the application roller 34 faces is supported by the contact support member 381 (see FIG. 6). The bias application contact 38a is electrically connected to an application bias generator (not shown), and the application bias generator can apply the application bias to the application roller 34 via the bias application contact 38a. it can. Then, by applying a coating bias to the coating roller 34, the toner particles contained in the developer 32 carried on the coating roller 34 are moved to the surface layer side of the developer 32, and the coating roller 34 to the developing roller 31. The application efficiency of the developer 32 can be improved. Further, as shown in FIG. 6, the bias applying contact 38a in the present embodiment is constituted by a leaf spring. Further, the biasing force BFar included in the bias applying contact 38a in the present embodiment is configured to be larger than the static friction force acting between the developing roller 31 and the application roller 34.

  The developing roller 31 and the coating roller 34 are rotatably disposed in the tank 33Y by inserting respective rotation shafts through holes provided in the tank 33Y. An E-ring 382b is attached to a predetermined position of the rotation shaft of the developing roller 31 outside the side wall of the tank 33Y on the (−X) side. The E-ring 382b abuts against the side wall of the tank 33Y, so that the developing roller 31 can be locked at a predetermined position (corresponding to the “developer carrier locking position” in the present invention). Thus, the E-ring 382b functions as the “developer-bearing member positioning portion” of the present invention. On the other hand, an E-ring 382a is attached to a predetermined position of the rotation shaft of the application roller 34 outside the side wall of the tank 33Y on the (+ X) side. The application roller 34 can be locked at a predetermined position (corresponding to the “application roller locking position” in the present invention) by the E ring 382a coming into contact with the side wall of the tank 33Y. Thus, the E-ring 382a functions as the “coating roller positioning portion” of the present invention.

  By the way, in this embodiment, the application roller 34 is designed so that play is generated in the thrust direction in consideration of manufacturing error, assembling property, and the like, and is movable in the thrust direction. Therefore, when an external force in the thrust direction is applied to the application roller 34, it moves. Accordingly, as the developing roller 31 and the applying roller 34 rotate while contacting each other during the developing process and the thrust force THar is generated, the applying roller 34 tends to move to the side where the thrust force THar is directed. Therefore, in this embodiment, the application roller 34 is prevented from moving by applying the biasing force BFar to the application roller 34 by the bias application contact 38a. The manner in which the application roller 34 is prevented from moving by applying the urging force BFar to the application roller 34 will be described in detail below.

a) Before rotation The biasing force BFar applied to the application roller 34 by the bias applying contact 38 a is larger than the static friction force acting between the developing roller 31 and the application roller 34. Therefore, the application roller 34 can move to the (−X) side by the biasing force BFar from the bias applying contact 38a until the E-ring 382a contacts the tank 33Y. The application roller 34 is locked at a predetermined position by the E ring 382a. In this embodiment, the developing roller 31 is also locked at a predetermined position by the E ring 382b (see FIG. 6A).

b) During rotation As the coating roller 34 and the developing roller 31 rotate while contacting, thrust forces THar and THdr are generated in the coating roller 34 and the developing roller 31, respectively. The direction to which the thrust force THar generated in the application roller 34 faces is the same as the direction of the biasing force BFar. Therefore, the two forces of the thrust force THar and the urging force BFar act on the application roller 34, whereby the application roller 34 is more firmly locked by the E ring 382a. At this time, the developing roller 31 is also locked by the E-ring 382b and does not move (see FIG. 6B).

c) Immediately after the rotation stops As the application roller 34 and the developing roller 31 stop rotating, the thrust forces THar and THdr generated on the respective rollers disappear (FIG. 6C). However, a biasing force BFar is applied to the application roller 34 in the (−X) direction by the bias applying contact 38a, and the application roller 34 is locked by the E-ring 382a and does not move.

  In the second embodiment, an E-ring 382a (application roller positioning portion) that locks the application roller 34 at a predetermined position (application roller engagement position) in the thrust direction is provided, and the application roller 34, the developing roller 31, and the like. The application roller 34 is urged by the bias application contact 38a (application roller urging member) in the same direction as the direction in which the application roller 34 is to be moved by the thrust force THar generated by the rotation of the contact roller. . Further, the biasing force BFar of the bias applying contact 38 a is configured to be larger than the static friction force acting between the developing roller 31 and the application roller 34. Therefore, for example, as in the present embodiment, the application roller 34 is designed so that play occurs in the thrust direction in consideration of manufacturing errors, assemblability, etc. The application roller 34 is moved to a predetermined position (application roller locking position) only by the urging force of the bias application contact 38a (application roller urging member) and is engaged by the E ring 38a (application roller positioning portion). Can be stopped. Therefore, the application roller 34 is positioned at a predetermined position when the apparatus is assembled. Accordingly, when the thrust force THar is generated on the application roller 34 during the developing operation, the application roller 34 is already locked at the predetermined position by the E-ring 382a, and the application force is generated by the thrust force THar generated on the application roller 34. The roller 34 does not move further. Further, the application roller 34 is firmly locked by the E-ring 382a at a predetermined position in the thrust direction by the application of two forces of the biasing force BFar and the thrust force THar that the bias applying contact 38a has. Therefore, during the developing operation, for example, even if the apparatus is tilted due to vibration, the application roller 34 can be reliably prevented from moving from a predetermined position. Further, since the application roller 34 can be reliably locked at a predetermined position immediately after the development operation starts, the movement of the application roller 34 relative to the development roller 31 during the development operation can be prevented more efficiently. It is possible to prevent the coating pattern of the developer 32 applied to 31 from being disturbed. In this way, it is possible to prevent development of the electrostatic latent image on the photosensitive member by the developing solution 32 on the developing roller 31 with the disordered coating pattern, thereby preventing deterioration in developing accuracy. The development accuracy can be improved.

<Third Embodiment>
FIG. 7 is a schematic diagram of the developing unit viewed from the direction of arrow A in FIG. 2 in the third embodiment of the image forming apparatus according to the present invention. The third embodiment is greatly different from the first and second embodiments in that a bias applying contact 38b is provided on the developing roller 31 as a developer carrying member urging member of the present invention, and for the coating roller of the present invention. The biasing contact 38a is provided on the application roller 34 as an urging member. The roller drive motor 310 is provided on the (+ X) side of the developing roller 31, and the roller drive motor 340 is provided on the (−X) side of the application roller 34. Further, an E-ring 383b as a developer bearing member positioning portion of the present invention and an E-ring 383a as a coating roller positioning portion of the present invention are provided inside the tank 33Y. Other configurations are the same as those in the first and second embodiments. Hereinafter, the third embodiment will be described in detail focusing on differences from the first and second embodiments. In addition, about the structure and operation | movement same as 1st and 2nd embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  On the surface of the coating roller 34, a plurality of grooves 34a provided obliquely with respect to the rotation direction D2 of the coating roller 34 are formed as in the first and second embodiments. Accordingly, when the application roller 34 and the developing roller 31 rotate while being in contact with each other, thrust forces THar and THdr are generated in the application roller 34 and the developing roller 31, respectively. In this embodiment, a bias application contact 38 a that urges the application roller 34 in the same direction as the side to which the thrust force THar generated in the application roller 34 faces is supported by the contact support member 381. Further, a bias applying contact 38b that urges the developing roller 31 in the same direction as the side to which the thrust force THdr generated in the developing roller 31 faces is supported by the contact support member 381 (see FIG. 7).

  The bias applying contacts 38a and 38b are electrically connected to a coating bias generator (not shown) and a developing bias generator 114, as in the first and second embodiments. Therefore, the application bias generator can apply the application bias to the application roller 34 via the bias application contact 38a, and the development bias generation unit 114 can apply the development bias to the development roller 31 via the bias application contact 38b. Can do. Further, as shown in FIG. 7, as in the first and second embodiments, the bias applying contacts 38a and 38b in the present embodiment are configured by leaf springs. Further, the biasing force BFar included in the bias applying contact 38a in the present embodiment is configured to be larger than the static friction force acting between the developing roller 31 and the application roller 34. On the other hand, the biasing force BFdr of the bias applying contact 38b in the present embodiment is a static friction force acting between the developing roller 31 and the photoconductor 11Y, and a static friction acting between the developing roller 31 and the application roller 34. It is configured to be greater than the sum of power.

  The developing roller 31 and the coating roller 34 are rotatably disposed in the tank 33Y by inserting respective rotation shafts through holes provided in the tank 33Y. An E ring 383b is attached to a predetermined position of the rotation shaft of the developing roller 31 inside the side wall of the tank 33Y on the (+ X) side. The E-ring 383b abuts against the inner wall of the tank 33Y, whereby the developing roller 31 can be locked at a predetermined position (corresponding to the “developer carrying member locking position” in the present invention). Thus, the E-ring 383b functions as the “developer-bearing member positioning portion” of the present invention. On the other hand, an E-ring 383a is attached to a predetermined position of the rotation shaft of the application roller 34 inside the side wall of the tank 33Y on the (−X) side. Then, the E-ring 383a abuts against the inner wall of the tank 33Y, whereby the application roller 34 can be locked at a predetermined position (corresponding to the “application roller lock position” of the present invention). Thus, the E-ring 383a functions as the “coating roller positioning portion” of the present invention.

  By the way, in the present embodiment, the application roller 34 and the developing roller 31 are designed so that play is generated in the thrust direction in consideration of manufacturing errors, assemblability, and the like, and are movable in the thrust direction. Therefore, when an external force in the thrust direction is applied to the application roller 34 and the developing roller 31, it moves. Accordingly, as the developing roller 31 and the application roller 34 rotate in contact with each other during the development process and the thrust forces THar and THdr are generated, the application roller 34 and the development roller 31 try to move toward the side where the thrust forces THar and THdr are directed. To do. Therefore, in this embodiment, the applying roller 34 and the developing roller 31 are prevented from moving by applying biasing forces BFar and BFdr to the applying roller 34 and the developing roller 31 by the bias applying contacts 38a and 38b. The manner in which the urging forces BFar and BFdr are applied to the coating roller 34 and the developing roller 31 to prevent the coating roller 34 and the developing roller 31 from moving will be described in detail below.

a) Before rotation The biasing force BFar applied to the application roller 34 by the bias applying contact 38 a is larger than the static friction force acting between the developing roller 31 and the application roller 34. Therefore, the application roller 34 can move to the (−X) side by the biasing force BFar from the bias applying contact 38a until the E-ring 383a contacts the tank 33Y. The application roller 34 is locked at a predetermined position by the E ring 383a. The biasing force BFdr applied to the developing roller 31 by the bias applying contact 38b is a static frictional force that acts between the developing roller 31 and the photosensitive member 11Y, and a static force that acts between the developing roller 31 and the coating roller 34. Greater than the sum of frictional forces. Therefore, the developing roller 31 can move to the (+ X) side by the biasing force BFdr from the bias applying contact 38b until the E-ring 383b contacts the tank 33Y. The developing roller 31 is locked at a predetermined position by the E-ring 383b (see FIG. 7A).

b) During rotation As the coating roller 34 and the developing roller 31 rotate while contacting, thrust forces THar and THdr are generated in the coating roller 34 and the developing roller 31, respectively. The direction to which the thrust force THar generated in the application roller 34 faces is the same as the direction of the biasing force BFar. Therefore, the two forces of the thrust force THar and the urging force BFar act on the application roller 34, whereby the application roller 34 is more firmly locked by the E ring 383a. Further, the side to which the thrust force THdr generated in the developing roller 31 is directed is the same as the direction of the biasing force BFdr. Therefore, the two forces of the thrust force THdr and the urging force BFdr act on the developing roller 31, so that the developing roller 31 is more firmly locked by the E ring 383b (see FIG. 7B).

c) Immediately after the rotation stops As the application roller 34 and the developing roller 31 stop rotating, the thrust forces THar and THdr generated on the respective rollers disappear (FIG. 6C). However, a biasing force BFar is applied to the application roller 34 in the (−X) direction by the bias applying contact 38a, and the application roller 34 is locked by the E-ring 383a and does not move. Further, a biasing force BFdr is applied to the developing roller 31 in the (+ X) direction by the bias applying contact 38b, and the developing roller 31 is locked by the E ring 383b and does not move.

  In the third embodiment, an E-ring 383a (application roller positioning portion) that locks the application roller 34 at a predetermined position (application roller engagement position) in the thrust direction is provided, and the application roller 34 is moved by the thrust force. The application roller 34 is urged by a bias application contact 38a (application roller urging member) in the same direction as the direction to be applied. On the other hand, an E-ring 383b (developer carrier positioning portion) for locking the developing roller 31 at a predetermined position (developer carrier locking position) in the thrust direction is provided, and the developing roller 31 is moved by the thrust force. The developing roller 31 is urged by a bias applying contact 38b (a developer carrying member urging member) in the same direction as the above. Therefore, the operational effects of the first and second embodiments can be achieved simultaneously.

<Fourth embodiment>
FIG. 8 is a schematic diagram of the developing unit viewed from the direction of arrow A in FIG. 2 in the fourth embodiment of the image forming apparatus according to the present invention. The fourth embodiment differs greatly from the first embodiment in that the side to which the thrust force generated by the application roller 341 and the developing roller 31 rotating while abutting is opposite to the direction of the first embodiment. The groove 34a is formed in the coating roller 341 so as to be in this direction. Further, a pin 384 is provided as the developer bearing member positioning portion of the present invention, and a cover 385 is provided as the coating roller positioning portion of the present invention. The rotor drive motor 340 is provided only on the application roller 341, and the developing roller 31 is provided with a gear 311 that can receive the drive force of the rotor drive motor 340. Other configurations are the same as those of the first embodiment. Hereinafter, the fourth embodiment will be described in detail focusing on differences from the first embodiment. In addition, about the structure and operation | movement same as 1st Embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  On the surface of the application roller 341, a plurality of grooves 34a provided obliquely with respect to the rotation direction D2 of the application roller 341 are formed in the opposite direction to the first embodiment. Accordingly, when the application roller 341 and the developing roller 31 rotate while being in contact with each other, thrust forces THar2 and THdr2 are generated in the application roller 341 and the developing roller 31, respectively. In this embodiment, a bias applying contact 38b for urging the developing roller 31 in the same direction as the side to which the thrust force THdr2 generated in the developing roller 31 faces (corresponding to the “urging member for developer carrying member” of the present invention). Is supported by the contact support member 381 (see FIG. 8). The bias applying contact 38b is electrically connected to the developing bias generating unit 114, and the developing bias generating unit 114 can apply a developing bias to the developing roller 31 via the bias applying contact 38b. Further, as shown in FIG. 8, the bias applying contact 38b in the present embodiment is constituted by a leaf spring. Further, the biasing force BFdr of the bias applying contact 38b in the present embodiment is a static friction force acting between the developing roller 31 and the photoreceptor 11Y, and a static friction acting between the developing roller 31 and the application roller 341. It is configured to be greater than the sum of power.

  The developing roller 31 and the coating roller 341 are rotatably disposed in the tank 33Y by inserting respective rotation shafts through holes provided in the tank 33Y. A pin 384 is inserted into a predetermined position of the rotation shaft of the developing roller 31 inside the side wall of the tank 33Y on the (−X) side. The developing roller 31 can be locked at a predetermined position (corresponding to the “developer carrying member locking position” of the present invention) by the pin 384 coming into contact with the inner wall of the tank 33Y. Thus, the pin 384 functions as the “developer-bearing member positioning portion” of the present invention. On the other hand, a cover 385 is disposed in the tank 33Y so as to cover the end of the rotation shaft of the application roller 341 outside the side wall of the tank 33Y on the (+ X) side. The application roller 341 is locked at a predetermined position (corresponding to the “application roller locking position” in the present invention) by the end of the application roller 341 on the (+ X) side being in contact with the inside of the cover 385. Can do. Thus, the cover 385 functions as the “coating roller positioning portion” of the present invention.

  A gear 311 is pivotally mounted on the (−X) side of the developing roller 31 instead of the roller drive motor. The gear 311 rotates by receiving a driving force from the roller driving motor 340. As the gear 311 rotates, the developing roller 31 rotates.

  By the way, in the present embodiment, the developing roller 31 is designed so that play is generated in the thrust direction in consideration of manufacturing errors, assemblability, and the like, and is movable in the thrust direction. Therefore, when an external force in the thrust direction is applied to the developing roller 31, it moves. Accordingly, as the developing roller 31 and the application roller 341 rotate while in contact with each other during the developing process and the thrust force THdr2 is generated, the developing roller 31 tends to move to the side where the thrust force THdr2 faces. Therefore, in this embodiment, the biasing contact BFdr is applied to the developing roller 31 by the bias applying contact 38b to prevent the developing roller 31 from moving. The manner in which the developing roller 31 is prevented from moving by applying the biasing force BFdr to the developing roller 31 will be described in detail below.

a) Before rotation The biasing force BFdr applied to the developing roller 31 by the bias applying contact 38b acts between the developing roller 31 and the photosensitive roller 11Y and the static friction force acting between the developing roller 31 and the applying roller 341. It is larger than the sum of the static frictional force. Therefore, the developing roller 31 can be moved to the (−X) side by the biasing force BFdr from the bias applying contact 38b until the pin 384 comes into contact with the tank 33Y. The developing roller 31 is locked at a predetermined position by a pin 384. In this embodiment, the application roller 341 is also locked at a predetermined position by the cover 385 (see FIG. 8A).

b) During rotation As the coating roller 341 and the developing roller 31 rotate while being in contact with each other, thrust forces THa2 and THdr2 are generated in the coating roller 341 and the developing roller 31, respectively. The side to which the thrust force THdr2 generated in the developing roller 31 faces is the same as the direction of the biasing force BFdr. Therefore, the two forces of the thrust force THdr2 and the urging force BFdr act on the developing roller 31, so that the developing roller 31 is more firmly locked by the pin 384. At this time, the application roller 341 is also locked by the cover 385 and does not move (see FIG. 8B).

c) Immediately after the rotation stops As the application roller 341 and the developing roller 31 stop rotating, the thrust forces THar2 and THdr2 generated on the respective rollers disappear (FIG. 8C). However, a biasing force BFdr is applied to the developing roller 31 in the (−X) direction by the bias applying contact 38b, and the developing roller 31 is locked by the pin 384 and does not move.

  In the fourth embodiment, a pin 384 (developer carrier positioning portion) for locking the developing roller 31 at a predetermined position (developer carrier locking position) in the thrust direction is provided, and the application roller 341 and the developing roller 341 are developed. The developing roller 31 is biased by a biasing contact 38b (biasing member for developer carrying member) in the same direction as the developing roller 31 tries to move by the thrust force THdr2 generated by rotating while being in contact with the roller 31. Energized. The biasing force BFdr of the bias applying contact 38b is the sum of the static friction force acting between the developing roller 31 and the photoconductor 11Y and the static friction force acting between the developing roller 31 and the application roller 341. It is comprised so that it may become larger. Therefore, for example, when the developing roller 31 is designed so that play is generated in the thrust direction in consideration of manufacturing errors and assemblability as in the present embodiment, and is movable in the thrust direction, The same operational effects as those of the first embodiment can be obtained.

<Fifth Embodiment>
FIG. 9 is a schematic diagram of the developing unit viewed from the direction of arrow A in FIG. 2 in the fifth embodiment of the image forming apparatus according to the present invention. The fifth embodiment is greatly different from the fourth embodiment in that a biasing force BFdr2 is applied to the developing roller 31 by using a coil spring 38c as a biasing member instead of the bias applying contact 38b. In addition, a disk 386 is provided as the developer bearing member positioning portion of the present invention, and an E-ring 382a is provided as the coating roller positioning portion of the present invention. Other configurations are the same as those of the fourth embodiment, and hereinafter, the fifth embodiment will be described in detail focusing on differences from the fourth embodiment. In addition, about the structure and operation | movement same as 4th Embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  The developing roller 31 and the coating roller 34 are rotatably disposed in the tank 33Y by inserting respective rotation shafts through holes provided in the tank 33Y. A disk 386 is attached to a predetermined position of the rotation shaft of the developing roller 31 outside the side wall of the (+ X) side tank 33Y. The disk 386 is brought into contact with the side wall of the tank 33Y, whereby the developing roller 31 can be locked at a predetermined position (corresponding to the “developer carrier locking position” of the present invention). Thus, the disk 386 functions as the “developer-bearing member positioning portion” of the present invention. On the other hand, an E ring 382a is attached to a predetermined position of the rotation shaft of the application roller 341 outside the side wall of the tank 33Y on the (−X) side. The E-ring 382a abuts against the side wall of the tank 33Y, so that the application roller 341 can be locked at a predetermined position (corresponding to the “application roller lock position” in the present invention). Thus, the E-ring 382a functions as the “coating roller positioning portion” of the present invention.

  On the surface of the application roller 341, a plurality of grooves 34a provided obliquely with respect to the rotation direction D2 of the application roller 341 are formed as in the fourth embodiment. Accordingly, when the application roller 341 and the developing roller 31 rotate while being in contact with each other, thrust forces THar2 and THdr2 are generated in the application roller 341 and the developing roller 31, respectively. In this embodiment, the coil spring 38c (corresponding to the “urging member for developer carrier” of the present invention) that biases the developing roller 31 in the same direction as the side to which the thrust force THdr2 generated in the developing roller 31 faces is provided. Is provided. The diameter of the coil portion of the coil spring is configured to be larger than the diameter of the rotating shaft of the developing roller 31, and is configured to be able to apply the urging force BFdr2 to the disk 386 attached to the rotating shaft ( (See FIG. 9). Thus, by energizing the disk 386, the developing roller 31 to which the disk 386 is attached can be energized. The biasing force BFdr2 of the coil spring 38c in this embodiment is a static friction force acting between the developing roller 31 and the photosensitive member 11Y, and a static friction force acting between the developing roller 31 and the application roller 341. It is configured to be larger than the sum of.

  In the fifth embodiment, a disk 386 (developer carrier positioning portion) for locking the developing roller 31 at a predetermined position in the thrust direction (developer carrier locking position) is provided, and the application roller 341 and the developing roller 341 are developed. The developing roller 31 is attached by a coil spring 38c (biasing member for developer carrying member) in the same direction as the developing roller 31 is about to move by the thrust force THdr2 generated by rotating while being in contact with the roller 31. It is fast. Further, the biasing force BFdr2 of the coil spring 38c is based on the sum of the static friction force acting between the developing roller 31 and the photoconductor 11Y and the static friction force acting between the developing roller 31 and the application roller 341. Is configured to be larger. Therefore, for example, as in the fourth embodiment, when the developing roller 31 is designed so that play is generated in the thrust direction in consideration of manufacturing errors, assemblability, etc., and is movable in the thrust direction. The same operational effects as in the fourth embodiment can be obtained.

<Sixth Embodiment>
FIG. 10 is a schematic diagram of the developing unit viewed from the direction of arrow A in FIG. 2 in the sixth embodiment of the image forming apparatus according to the present invention. The sixth embodiment is greatly different from the fourth embodiment in that a biasing force BFdr3 is applied to the developing roller 31 by using a plate spring 38d as a biasing member instead of the bias applying contact 38a. The urging force BFdr3 is larger than the sum of the static friction force acting between the developing roller 31 and the photoconductor 11Y and the static friction force acting between the developing roller 31 and the application roller 341. It is configured as follows. The shape of the leaf spring 38d is L-shaped as shown in FIG. Further, a flange portion 387b is formed on the (−X) side rotating shaft of the developing roller 31 as the developer carrier positioning portion of the present invention. On the other hand, a flange portion 387a is formed on the rotation shaft on the (+ X) side of the application roller 341 as the application roller positioning portion of the present invention. Other configurations are the same as those of the fourth embodiment, and the same effects as those of the fourth embodiment are achieved.

<Seventh embodiment>
FIG. 11 is a schematic view showing a wire bar in the seventh embodiment. The main difference between this embodiment and the first to sixth embodiments is that the wire bar 39 is used instead of the anilox roller as the application roller, and other configurations are the first to sixth embodiments. It is the same. Hereinafter, the seventh embodiment will be described in detail focusing on differences from the first to sixth embodiments. In addition, about the structure and operation | movement same as 1st thru | or 6th embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  The wire bar 39 can be configured by, for example, winding a wire 391 having a wire diameter of 100 μm around a core bar with a pitch feeling of 100 μm. A recess 39a between the wires formed by winding the wire 391 around the core has the same effect as the groove 34a in the anilox roller (coating rollers 34, 341).

  With such a configuration, since the surface roughness of the wire bar 39 is relatively small, the static frictional force at the contact portion between the wire bar 39 and the developing roller 31 can be reduced. Therefore, the wire bar 39 and the developing roller 31 can be relatively moved in the thrust direction while being in contact with each other. Therefore, the wire bar and the developer carrier can be reliably moved in the thrust direction while being brought into contact with each other, and can be moved to a predetermined locking position in the thrust direction in a short time.

<Others>
The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit of the present invention. For example, in each of the above-described embodiments, the magnitudes of the urging forces BFar, BFdr, BFdr2, and BFdr3 are set so that the developing roller 31 or the application roller 34 can be moved in the thrust direction only by the urging force. However, the biasing forces BFar, BFdr, BFdr2, and BFdr3 may be set to such a magnitude that the developing roller 31 or the coating roller 34 cannot be moved in the thrust direction only by the biasing force. For example, as shown in FIG. 12, the bias applying contact 38b2 (biasing member for the developer carrying member) includes a static friction force acting between the developing roller 31 (developer carrying member) and the photosensitive member, and the developing roller. The biasing force BFdr4 may be smaller than the sum SF of the static friction force acting between the application roller 31 and the application roller 34. With such a configuration, during the developing operation, the developing roller 31 is moved to a predetermined locking position in the thrust direction in a short time by the two forces of the thrust force THdr and the biasing force BFdr4 of the bias applying contact 38b2. It can be locked by the E-ring 382b (developer carrier positioning portion). In this way, the developing roller 31 can be locked at a predetermined locking position in a short time. Then, with these two forces THdr and BFdr4, the developing roller 31 can be reliably locked by the E ring 382b at a predetermined locking position. Accordingly, it is possible to prevent the development roller 31 from moving relative to the photosensitive member and the application roller 34 during the development operation, thereby preventing the development accuracy from being deteriorated and improving the development accuracy.

  The biasing contact (plate spring) in the first to fourth embodiments, the coil spring in the fifth embodiment, and the plate spring in the sixth embodiment may be variously combined as the biasing member.

  Moreover, as an urging | biasing member, it can comprise with various members besides the above-mentioned structure. In short, any configuration may be used as long as the application roller or the developer carrying member can be reliably urged. Such an urging member can be constituted by a rubber push, for example.

  In the fourth to sixth embodiments, the roller drive motors 310 and 340 and the gear 311 may be provided on the opposite (+ X) side and the urging member may be provided on the (−X) side of the application roller 341. I do not care. With such a configuration, the same operational effects as those of the second embodiment can be obtained.

  In the fifth and sixth embodiments, similarly to the third embodiment, the roller drive motor 340 is provided on the (+ X) side of the application roller 341, and the roller drive motor 310 is provided on the (−X) side of the developing roller 31. The urging member may be provided on the (−X) side of the application roller 341 and the (+ X) side of the developing roller 31. With such a configuration, the same operational effects as those of the third embodiment can be obtained.

  Also, as a biasing member, the coil spring in the fifth embodiment and the leaf spring in the sixth embodiment may be used in other embodiments.

  Further, the roller driving method in the fourth embodiment may be used in other embodiments.

  In the above embodiment, the application roller and the developing roller are urged by the urging member from the other end opposite to the one end where the roller drive motor is provided, but the roller drive motor is provided. Of course, a configuration in which the application roller and the developing roller are urged from the one end portion of the end may be employed.

  Moreover, you may use the coil spring in 5th Embodiment, and the leaf | plate spring in 6th Embodiment as a bias provision contact.

  Moreover, you may use the positioning part (E ring, a cover, a pin, a disk, a flange) in the said embodiment in any embodiment, respectively. Further, the positioning portion may have any configuration as long as it can reliably lock the developer carrier or the application roller.

  In the above embodiment, the exposure unit 20 is provided in a one-to-one correspondence with each of the photoconductors 11Y, 11M, 11C, and 11K, and each of the photoconductors 11Y, 11M, 11C, and 11K has a corresponding electrostatic latent. Although configured to form an image, for example, one exposure unit is provided, and the irradiation direction of the laser beam is switched using a mirror or the like, thereby corresponding to each of the photoreceptors 11Y, 11M, 11C, and 11K. The electrostatic latent image may be formed. In addition, an exposure unit using an LED array may be used, or a latent image writing unit that performs so-called writing charging may be used. In short, any configuration may be used as long as it can form a one-to-one electrostatic latent image on each of the photoconductors 11Y, 11M, 11C, and 11K.

  In the above-described embodiment, the regulation blade 35 performs the trail regulation. However, the regulation blade 35 may be arranged so that the tip of the regulation blade 35 faces the upstream side in the rotation direction of the application roller 34 to perform so-called counter regulation. I do not care.

  In the above embodiment, the present invention is embodied in a tandem color printer. However, the configuration according to the present invention may be applied to a so-called monochrome printer.

  In the above embodiment, a printer that prints an image supplied from an external device such as a host computer on transfer paper is described. However, the present invention is not limited to this, and includes a copying machine, a facsimile machine, and the like. The present invention can be applied to a general electrophotographic image forming apparatus. In short, a liquid developer in which toner is dispersed in a liquid carrier is once carried by an application roller, and then the carried liquid developer is applied to the developer carrier and the liquid developer applied to the developer carrier. Thus, the present invention can be applied to all image forming apparatuses that develop an electrostatic latent image on a latent image carrier.

  DESCRIPTION OF SYMBOLS 11 ... Photosensitive body (latent image carrier), 31 ... Developing roller (developer carrier), 32 ... Developer (liquid developer), 34, 341 ... Application roller (anilox roller), 38a, 38b, 38b2 Bias applying contact (biasing member), 38c ... coil spring (biasing member), 38d ... leaf spring (biasing member), 382a, 382b, 383a, 383b ... E-ring (positioning portion), 384 ... pin (positioning portion) ), 385 ... Cover (positioning part), 386 ... Disc (positioning part), 387a, 387b ... Flange (positioning part), 39 ... Wire bar, D2 ... First direction, BFar, BFdr, BFdr2, BFdr3, BFdr4 ... Power, THdr, THdr2, THar, THar2 ... Thrust force, SF ... Friction force

Claims (6)

And the current image-carrying member,
A groove provided obliquely with respect to the rotation direction, and the liquid developer is conveyed to a position in contact with the developer carrier while carrying the liquid developer in the groove; An application roller to apply to
A coating roller for positioning portion for engaging with the coating cloth roller locking position that put perpendicular or in a thrust direction substantially perpendicular to the rotational direction of the application roller,
Wherein the application roller and the developer carrying member in the direction towards the applicator roller you move by the thrust force generated by rotating while contacting, and a biasing member for applying roller for biasing the application roller A liquid developing apparatus comprising: The urging member for applying roller, the developer carrying member and the liquid developing device according to claim 1, wherein has a greater biasing force than the static friction force acting between the coating roller. It said biasing member is a liquid developing device according to any one of claims 1 to 2 is a biasing contact. Liquid developing device according to any one of 3 to the biasing member claims 1 a spring. The coating roller is liquid developing device according to any one of claims 1 a wire bar 4.   A latent image carrier;
  A developer carrier for developing a liquid developer in contact with the latent image carrier;
  While rotating in the first direction and having a groove provided obliquely with respect to the first direction, the liquid developer is carried in the groove and conveyed to a position in contact with the developer carrier. An application roller for applying the liquid developer to the developer carrier;
  A coating roller positioning portion that locks at a coating roller locking position in a thrust direction that is orthogonal or substantially orthogonal to the rotation direction of the coating roller;
  A biasing member for a coating roller that biases the coating roller in a direction in which the coating roller moves by a thrust force generated by rotating the coating roller and the developer carrying member in contact with each other;
  An image forming apparatus comprising:

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