JP2011028287A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve quality of color images by preventing displacement of a developer carrier during development processing to improve development precision, in a configuration for applying a liquid developer to the developer carrier using an application roller having a slanted groove. <P>SOLUTION: Image forming operation (developing processing) is performed after all development rollers are moved to developer carrier locking positions by thrust generated by rotating and driving the development rollers and the application roller, and are fixed by E rings, respectively. Displacement of the development rollers is prevented during the development processing, to improve development precision, thereby improving quality of the color images to be formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

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, the configuration of the above-described conventional apparatus is also applied to an image forming apparatus that forms a color image by superimposing toner images of four colors (yellow, magenta, cyan, and black) on a transfer medium such as an intermediate transfer belt. Can do. That is, it is possible to provide four developing means for each color, each composed of the developer carrier and the application roller. A color image can be formed by superimposing four color toner images formed for each developing unit on a transfer medium. However, in the developing means described above, when the rotation operation of the application roller and the developer carrier is started in order to execute the development process (step), a thrust force is generated on the application roller and the developer carrier. For this reason, the application roller and the developer carrier are relatively moved in the thrust direction, and the positions of the application roller and the developer carrier in the thrust direction may be temporarily unstable. As a result, the developing operation is executed while the positions of the application roller and the developer carrier in the thrust direction are unstable, and the following problems may occur.

  For example, since the position of the developer carrier relative to the latent image carrier and the application roller in the thrust direction is not stable, the contact position of the developer carrier relative to the latent image carrier in the thrust direction may become unstable. In this case, the toner image formed by developing the electrostatic latent image on the latent image carrier may be deteriorated. In addition, the contact position of the developer carrier with respect to the application roller in the thrust direction is also 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, and deteriorates the formed toner image. Further, since the position of the application roller with respect to the developer carrying member in the thrust direction is not stable, the application pattern of the liquid developer applied to the developer carrying member is disturbed, and the development accuracy is deteriorated and formed. The toner image may be deteriorated. A color image formed by superimposing such deteriorated toner images on a transfer medium is liable to cause a difference in color and color shift, which is one of the causes of quality deterioration of the color image. .

  The present invention has been made in view of the above problems, and in a configuration in which a liquid developer is applied to a developer carrier by an application roller having an oblique groove, development accuracy can be prevented by preventing movement of the developer carrier during development processing. The first object is to improve the quality of the color image to be formed.

  Further, according to the present invention, in the configuration in which the liquid developer is applied to the developer carrying member by the application roller having the oblique grooves, the movement of the application roller during the development processing is prevented to improve the development accuracy, and the color image to be formed The second object is to improve quality.

  In order to achieve the first object, the present invention stores a plurality of liquid developers of different colors and executes a developing process using the liquid developers to form a toner image. And an image forming apparatus including: a transfer unit that transfers a toner image formed by each of the plurality of developing units to a transfer medium; and a control unit that controls execution timing of the developing process by each of the plurality of developing units. In the apparatus, each of the plurality of developing units is rotated while carrying the liquid developer stored in the developing unit on the outer peripheral surface thereof, and is conveyed to a developing position for performing the developing process. A developer carrying member that performs rotation in the first direction, and has a plurality of grooves provided obliquely with respect to the first direction on the surface thereof, and is stored in the developing means. An application roller that transports the liquid developer to the developer carrier while carrying the liquid developer in the groove and applies the liquid developer to the developer carrier, and a predetermined development in a thrust direction substantially orthogonal to the first direction. A developer carrier positioning unit that latches the developer carrier at the developer carrier latching position, and the control unit rotates and drives the developer carrier and the application roller to perform all the development. The developing process is performed after the developer carrier is locked by the developer carrier positioning portion at the developer carrier locking position.

  Further, the image forming method according to the present invention includes a plurality of developing units that store liquid developers of different colors and perform a developing process using the liquid developers to form a toner image, A transfer unit that transfers a toner image formed by each of the plurality of developing units to a transfer medium; and a control unit that controls execution timing of a developing process by each of the plurality of developing units. A developer carrying member for carrying out the developing process by rotating the liquid developer stored in the developing means while carrying the liquid developer on the outer peripheral surface thereof and transporting it to the developing position for carrying out the developing process; A plurality of grooves provided obliquely with respect to the first direction are provided on the surface thereof so as to be rotatable in one direction, and the liquid developer stored in the developing means is carried in the grooves. Shina An application roller for transporting the developer carrier to the developer carrier and applying the liquid developer to the developer carrier, and a predetermined developer carrier in a thrust direction substantially perpendicular to the first direction. In the image forming apparatus including the developer carrier positioning portion that is locked at the locking position, the developer carrier and the application roller are driven to rotate in each of the plurality of developing units. A step of moving the body in a thrust direction toward the positioning portion for the developer carrier, and a step of locking the developer carrier at the developer carrier locking position in each of the plurality of developing means, And a step of executing the development processing operation after all the developer carriers are locked at the developer carrier locking position.

  In the invention configured as described above, the application roller is rotatably provided in the first direction, and when it is driven to rotate together with the developer carrier, a thrust force is generated in a thrust direction substantially orthogonal to the first direction. . The developer carrier is moved in the thrust direction by the thrust force. Therefore, in the present invention, a developer carrier positioning portion is provided in each developing means. For this reason, the developer carrier that moves by the thrust force is locked at a predetermined developer carrier locking position in the thrust direction, and the developer carrier is further prevented from moving from the locking position. Can do. That is, the developer carrier is positioned at the developer carrier locking position. In this way, after all the developer carrying members are locked at the developer holding member locking position and positioned at the locking position, development processing is executed by each developing means. Therefore, the developer carrying member can be prevented from moving during the development process, so that the development accuracy can be improved and a highly accurate toner image can be formed. Further, by transferring the toner image with high accuracy to the transfer medium by the transfer means, the accuracy of the toner image transferred onto the transfer medium is improved. For this reason, for example, when a color image is formed by superimposing different color toner images formed by each developing unit on a transfer medium, the accuracy of each toner image transferred onto the transfer medium is improved. Can do. Therefore, since the color image is formed by superimposing the toner images with improved accuracy on the transfer medium, the quality of the color image can be improved.

  Further, according to the present invention, as a first aspect for achieving the second object, each of the plurality of developing units is a coating roller that locks the coating roller at a predetermined coating roller locking position in the thrust direction. And a controller for rotating the developer carrier and the application roller so that all of the application rollers are locked by the application roller positioning portion at the application roller locking position. The development processing is executed later. In the invention configured as described above, when a thrust force is generated in the thrust direction, not only the developer carrying member but also the application roller moves in the thrust direction due to the thrust force. That is, each developing means is provided with a coating roller positioning portion. For this reason, the application roller moving by the thrust force is locked at a predetermined application roller locking position in the thrust direction, and the application roller can be further prevented from moving from the locking position. That is, the application roller is positioned at the application roller locking position. In this way, after all the application rollers are locked at the application roller locking position and positioned at the locking position, development processing is executed by each developing means. Therefore, the effects described below can be achieved at the same time as the effects described above. That is, it is possible to prevent the application roller from moving relative to the developer carrying member during the development process, and to prevent the application pattern of the liquid developer to be applied to the developer carrying member from being disturbed. In this way, it is possible to prevent the development processing from being performed with the liquid developer on the developer carrying member whose coating pattern is disturbed, thereby preventing the development accuracy from deteriorating and improving the development accuracy. Can be achieved. Further, by improving the development accuracy in this way, toner images of different colors improved in accuracy are transferred onto a transfer medium by a transfer means, and a plurality of color toner images are superimposed on the transfer medium to form a color image. Therefore, the quality of the color image can be improved.

  According to a second aspect of the present invention for achieving the second object, liquid developers of different colors are stored and a developing process is performed using the liquid developers to form a toner image. A plurality of developing units, a transfer unit that transfers a toner image formed by each of the plurality of developing units to a transfer medium, and a control unit that controls execution timing of the developing process by each of the plurality of developing units. In the image forming apparatus, each of the plurality of developing units is rotated to a developing position for carrying out the developing process by rotating while carrying the liquid developer stored in the developing unit on the outer peripheral surface thereof. A developer carrier that is transported to perform the development process, and is provided rotatably in the first direction, and has a plurality of grooves provided obliquely with respect to the first direction on the surface thereof, developing A coating roller that transports the liquid developer stored in a stage to the developer carrying body while carrying the liquid developer in the groove and applies the liquid developer to the developer carrying body, and substantially orthogonal to the first direction. A coating roller positioning portion that locks the coating roller at a predetermined coating roller locking position in a thrust direction, and the control unit rotates and drives the developer carrier and the coating roller to perform all of the coating The developing process is performed after the roller is locked by the coating roller positioning portion at the coating roller locking position.

  Further, the image forming method according to the present invention includes a plurality of developing units that store liquid developers of different colors and perform a developing process using the liquid developers to form a toner image, A transfer unit that transfers a toner image formed by each of the plurality of developing units to a transfer medium; and a control unit that controls execution timing of a developing process by each of the plurality of developing units. A developer carrying member for carrying out the developing process by rotating the liquid developer stored in the developing means while carrying the liquid developer on the outer peripheral surface thereof and transporting it to the developing position for carrying out the developing process; A plurality of grooves provided obliquely with respect to the first direction are provided on the surface thereof so as to be rotatable in one direction, and the liquid developer stored in the developing means is carried in the grooves. Shina An application roller that conveys the liquid developer to the developer carrier and applies the liquid developer to the developer carrier, and a predetermined application roller locking position in the thrust direction substantially perpendicular to the first direction. In the image forming apparatus provided with a coating roller positioning portion to be locked, in each of the plurality of developing units, the developer carrying member and the coating roller are driven to rotate to thereby apply the coating roller to the coating roller positioning portion. A step of moving the coating roller in the thrust direction toward each of the plurality of developing units, a step of locking the coating roller at the coating roller locking position in each of the plurality of developing units, and all the coating rollers at the coating roller locking position And the step of executing the development processing after being locked in step (b).

  In the invention configured as described above, the application roller is rotatably provided in the first direction, and when it is driven to rotate together with the developer carrier, a thrust force is generated in a thrust direction substantially orthogonal to the first direction. . The application roller moves in the thrust direction by this thrust force. Therefore, in the present invention, each developing means is provided with a coating roller positioning portion. For this reason, the application roller moving by the thrust force is locked at a predetermined application roller locking position in the thrust direction, and the application roller can be further prevented from moving from the locking position. That is, the application roller is positioned at the application roller locking position. In this way, after all the application rollers are locked at the application roller locking position and positioned at the locking position, development processing is executed by each developing means. Accordingly, the movement of the application roller relative to the developer carrier during development processing can be prevented, and the application pattern of the liquid developer applied to the developer carrier can be prevented from being disturbed, so that the development accuracy is deteriorated. Can be prevented and development accuracy can be improved. In addition, by improving the development accuracy in this way, the quality of the color image to be formed can be improved by superimposing a plurality of color toner images with improved accuracy on a transfer medium to form a color image. Can do.

  In addition, each of the plurality of developing units can form a registration mark for correcting a relative positional shift in the plurality of colors as the toner image. With such a configuration, after the developer carrier or application roller in the thrust direction is moved from an unstable state to a stable state (positioned to a predetermined locking position), the registration mark is moved. Is formed as a toner image, and the toner image is transferred onto a transfer medium, whereby a registration mark is formed on the transfer medium. As described above, since the processing for correcting the positional deviation can be executed while the positions of the developer carrying member and the application roller in the thrust direction are stable, the correction accuracy of the correction processing can be improved.

  By the way, due to problems such as manufacturing accuracy and assembly errors, the value of the magnitude of the thrust force generated when the developer carrier and the application roller are driven to rotate, and when the developer carrier and the application roller are attached to the apparatus. The value of the amount of play usually varies for each developing means. Therefore, by rotating the developer carrier and the application roller, the rotational drive for rotating the developer carrier and the application roller necessary until the developer carrier or the application roller is positioned at a predetermined locking position. In many cases, the time differs depending on each developing means. Therefore, in each of the plurality of developing means, it is necessary from the start of rotation of the developer carrier and the application roller until at least one of the developer carrier and the application roller is positioned at a predetermined locking position. It is preferable that a storage unit for storing the rotation driving time is further provided, and the control unit adjusts the timing for executing the development processing based on the rotation driving time stored in the storage unit. With such a configuration, it is possible to adjust the timing for executing the development processing based on the necessary rotational drive time for each of the plurality of developing units stored in the storage unit. That is, for all the developing means, the developer carrier or the application roller required for moving the developer carrier or the application roller from the unstable position in the thrust direction to the predetermined locking position, and It is possible to know the time during which the application roller must be rotated at a minimum. Then, after the developer carrying member and the application roller are rotationally driven for the necessary time, the developing process can be executed. Therefore, the developer carrier and the application roller are not driven to rotate more than necessary, which is efficient.

  In general, the higher the rotational driving speed of the developer carrier and the application roller, the greater the thrust force generated on the developer carrier and the application roller. For this reason, the control unit is configured such that, for each of the plurality of developing units, the developer carrier and the application roller until at least one of the developer carrier and the application roller is positioned at a predetermined locking position. If the rotational drive speed is set to a speed faster than the rotational drive speed during the development processing, it is efficient. With this configuration, the rotational speed of the developer carrier and the application roller is set to be higher than the rotational speed of the developing process until the developer carrier or the application roller is positioned at a predetermined locking position. Set fast. Therefore, it is possible to reduce the time until the developer carrier or the application roller is positioned at the predetermined locking position, and therefore it is possible to reduce the time until the development processing is executed.

  In each of the plurality of developing units, the application roller and the developer carrier are relatively moved by a thrust force generated by the application roller and the developer carrier being rotated while being in contact with each other. It is good also as a structure further equipped with the urging | biasing member which has the urging | biasing force of the direction which moves the said application roller and the said developer carrier relative to the same direction as the direction to do. With such a configuration, the developer carrier and the application roller are moved to a predetermined locking position in the thrust direction in a short time by the two forces of the thrust force and the urging force of the urging member, and the positioning unit Can be locked. Thus, the developer carrier and the application roller can be brought into the locked state at the predetermined locking position in a short time, so that the time until the development processing is executed can be shortened. Further, the developer carrier and the application roller can be reliably locked at a predetermined locking position by the two forces of the thrust force and the biasing force.

  Each of the plurality of developing means further includes position detecting means for detecting a positioning state of the developer carrier and the application roller in a thrust direction substantially orthogonal to the first direction, and the control means includes the control means, The execution timing of the development processing may be controlled based on position information from the position detection unit. With such a configuration, it is possible to detect the positioning state of the developer carrier and the application roller in the thrust direction in real time, and to control the timing of executing the development process based on the detected position information. That is, it is detected in real time whether the developer carrier and the application roller are positioned at the predetermined locking position, and the development process is executed immediately after the developer carrier or the application roller is positioned at the predetermined locking position. can do. Accordingly, it is possible to prevent the rotation driving operation from being unnecessarily continued until the development processing is executed, and thus the efficiency is high.

  The application roller may be an anilox roller having the groove formed on the surface thereof. With such a configuration, the liquid developer measured in a certain amount can be applied to the developer carrying member by carrying the liquid developer in the groove of the anilox roller. Therefore, it is possible to apply the liquid developer to the developer carrying member accurately and uniformly. As described above, since the developing process can be executed by the developer carrying member uniformly coated with the liquid developer, the developing accuracy can be improved.

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. 6 is a flowchart showing first image forming processing. The schematic diagram of the image development part seen from the direction of the arrow A of FIG. 2 in 2nd Embodiment. 10 is a flowchart showing second image forming processing. The schematic diagram of the image development part seen from the direction of arrow A of FIG. 2 in 3rd Embodiment. 10 is a flowchart showing third image forming processing in the fourth embodiment. 10 is a flowchart showing a fourth image forming process in the fifth embodiment. The figure which shows one example of a position shift correction process. The figure which shows the internal structure of the printer which is 6th Embodiment. FIG. 14 is a block diagram showing an electrical configuration of the printer of FIG. 13. 10 is a flowchart showing fifth image forming processing in the sixth embodiment. 6 is a time chart showing the start timing of an image forming operation.

<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 11Y, 11M, 11C, and 11K of yellow (Y), magenta (M), cyan (C), and black (K) are provided in the apparatus main body. 2 in parallel. 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 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 controls each part of the engine unit 1 in accordance with the control signal from the main control unit 100. By controlling, an image corresponding to the image signal is printed out on a recording medium 4 such as a transfer sheet, a copy sheet, and an OHP sheet conveyed from a sheet feeding cassette 3 disposed in the lower part of the apparatus main body 2.

  In the engine unit 1, four photoconductors 11 </ b> Y, 11 </ b> M, and 11 </ b> C arranged in parallel along the circumferential direction 47 of the intermediate transfer belt 41 (corresponding to the “transfer medium” of the present invention) that is one component of the transfer unit 40. , 11K, a charging unit 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 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 (“ The control means ”) outputs a control signal corresponding to the image signal to the exposure control unit 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. (Latent image forming process). When forming a patch image as necessary, the CPU 113 sends a control signal corresponding to an image signal of a predetermined pattern (for example, a solid image, a fine line image, a white thin line image, a registration mark). A yellow electrostatic latent image corresponding to the pattern is given to the exposure control unit 112 and formed on the photoreceptor 11Y.

  The yellow electrostatic latent image formed in this way is visualized by the yellow toner supplied from the developing roller 31 of the developing unit 30Y (developing process). 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 43e, 44, 45, and is moved in a direction 47 (counterclockwise in FIG. 1) that is driven by the photoconductor 11Y by a drive motor (not shown). It runs around at a peripheral speed equal to that of the photoreceptor 11Y. 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 ( Transcription process). As described above, in this embodiment, the primary transfer rollers 53Y, 53M, 53C, and 53K and the transfer bias generator 115 function as the “transfer means” of the present invention.

  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 “image forming operation” in this specification refers to full-color or monochrome toner on the intermediate transfer belt 41 by executing the “latent image forming process”, “developing process”, and “transfer process”. It represents the operation of forming an 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 receives a print command including the image signal from the external device. Is received via the interface 102, converted to 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 (corresponding to the “developing unit” of the present invention) will be described in detail with reference to FIGS. 2 and 4 to 6. 4 is a conceptual perspective view of an anilox roller having grooves formed on the surface, FIG. 5 is a schematic view of a developing unit viewed from the direction of arrow A in FIG. 2, and FIG. 6 is a flowchart showing a first image forming process. . 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 agitation roller 37 rotates in the same direction as the rotation direction of the application roller 34 (clockwise in FIG. 2). 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. The groove pitch (in the thrust direction, the period between the peaks forming the grooves 34a) is preferably approximately 55 to 250 μm depending on the required film thickness of the developer 32. In this embodiment, the groove pitch is about 170 μm, the peak width is about 45 μm, the width of the groove 34 a is 30 μm, and the depth of the groove 34 a is about 50 μm.

  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 cleans a developing roller made of rubber 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 16 in the rotation direction D1 of the developing roller 31. It has a blade 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 configurations and operations of the developing roller 31 and the application roller 34 will be described in more detail with reference to FIGS. 5 and 6. 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, the developing roller 31 and the application 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, 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. The play in the thrust direction is preferably about 0.7 mm to 1.0 mm. In the present embodiment, the above-described play is configured to be about 0.8 mm. In the present embodiment, the first image forming process shown in FIG. 6 is executed. Hereinafter, the first image forming process will be described in detail.

a) Before Image Forming Operation In this embodiment, the developing roller 31 is not locked by the E-ring 382b at a predetermined locking position, and is more (+ X) than the predetermined locking position in the play in the thrust direction. Stops at a position close to the side. Also, the application roller 34 is not locked by the E ring 382a at a predetermined locking position, and stops at a position closer to the (−X) side than the predetermined locking position in the play in the thrust direction. (See FIG. 5A). In this embodiment, the first image forming process shown in FIG. 6 is executed. Until a print command for requesting the execution of the image forming operation is input from an external device such as a host computer via the interface 102. The CPU 113 (corresponding to the “control unit” of the present invention) enters a standby state (step S1).

b) During rotational drive operation When a print command is input from an external device such as a host computer via the interface 102, the CPU 113 gives a control command to the roller drive unit 118 to rotationally drive the application roller 34 and the developing roller 31 ( Step S2). At this time, the application roller 34 and the developing roller 31 rotate while being in contact with each other, so that thrust forces THar and THdr are generated in the application roller 34 and the developing roller 31, respectively. Therefore, the application roller 34 moves to the side where the thrust force THar is directed until it is locked at a predetermined locking position by the E-ring 382a. Further, the developing roller 31 moves to the side where the thrust force THdr is directed until it is locked at a predetermined locking position by the E-ring 382b.

The CPU 113 rotates the application roller 34 and the developing roller 31 a predetermined number of times (step S3). The predetermined number of times that the coating roller 34 and the developing roller 31 are rotationally driven is the number of times determined by the amount of play in the thrust direction and the groove pitch of the grooves 34a formed in the coating roller 34.
(Thrust play) / (Groove pitch)
That is the number of times. In this embodiment,
(800 μm) / (170 μm) ≈4.7
To at least 5 times. Therefore, by executing the rotation driving operation of the coating roller 34 and the developing roller 31 a predetermined number of times, the coating roller 34 and the developing roller 31 are securely locked by the E-rings 382a and 382b at the respective locking positions. (See FIG. 5 (b)).

c) Image forming operation When the CPU 113 rotates the application roller 34 and the developing roller 31 a predetermined number of times, the image forming operation is executed (step S4). At this time, by the thrust forces THar and THdr generated on the application roller 34 and the developing roller 31, the application roller 34 and the development roller 31 are securely locked by the E-rings 382a and 382b at predetermined locking positions (FIG. 5 (c)).

  As described above, in this embodiment, the application roller 34 is provided so as to be rotatable in the direction of the arrow D2, and when rotated with the developing roller 31, the X direction substantially orthogonal to the rotation direction D2 of the application roller 34. Thrust forces THar and THdr are generated in the (thrust direction). The application roller 34 and the developing roller 31 are moved in the X direction by the thrust forces THar and THdr. Therefore, in this embodiment, E-rings 382a and 382b (coating roller positioning unit, developer carrier positioning unit) are provided in each developing unit. Therefore, the developing roller 31 that is moved by the thrust force THdr is locked at a predetermined developer carrier locking position in the X direction, and the development roller 31 can be further prevented from moving from the locking position. it can. That is, the developing roller 31 is positioned at the developer carrier locking position. Further, the application roller 34 that is moved by the thrust force THar is locked at a predetermined application roller locking position in the X direction, and the application roller 34 can be further prevented from moving from the locking position. That is, the application roller 34 is positioned at the application roller locking position. In this way, after all the developing roller 31 and the application roller 34 are locked at predetermined locking positions and positioned at the locking positions, development processing (image forming operation) is performed by each developing unit. .

  Accordingly, the movement of the developing roller 31 during the developing process can be prevented, so that the developing accuracy can be improved and a highly accurate toner image can be formed. Further, the movement of the application roller 34 with respect to the development roller 31 during the development process can be prevented, and the application pattern of the developer 32 applied to the development roller 31 can be prevented from being disturbed. In this way, it is possible to prevent the developing process from being performed with the developing solution 32 on the developing roller 31 whose coating pattern is disturbed, thereby preventing the development accuracy from deteriorating and improving the development accuracy. Can be planned. In addition, the accuracy of the toner image transferred onto the intermediate transfer belt 41 is improved by transferring the toner image improved in accuracy by improving the development accuracy to the intermediate transfer belt 41 in this way. Therefore, when a color image is formed by superimposing different color toner images formed by the developing units 30Y, 30M, 30C, and 30K on the intermediate transfer belt 41, each of the toner images transferred onto the intermediate transfer belt 41 is transferred. The accuracy of the toner image can be improved. Therefore, since the color image is formed by superimposing the toner images with improved accuracy on the intermediate transfer belt 41, the quality of the color image can be improved.

  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. 7 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, and FIG. 8 is a flowchart showing the second image forming process. The second embodiment is greatly different from the first embodiment in that protrusions 312 and 342 are provided on the (+ X) side of the rotation shafts of the developing roller 31 and the application roller 34, respectively. In other words, position sensors 313 and 343 are provided corresponding to 342. In the second embodiment, the second image forming process is executed instead of the first image forming process. Other configurations are the same as those of the first embodiment, and hereinafter, the second 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.

  The position sensors 313 and 343 (corresponding to the “position detecting means” of the present invention) are composed of, for example, a photo interrupter having a light emitting portion (for example, LED) and a light receiving portion (for example, a photodiode) arranged to face each other. 342 is disposed on the (+ X) side where the protrusion 342 is provided, and detects the presence or absence of the protrusions 312 and 342 and outputs a detection signal. In this embodiment, when the developing roller 31 is locked at a predetermined locking position by the E-ring 382b, the protrusion 312 cannot be detected by the position sensor 313. Further, when the application roller 34 is locked at a predetermined locking position by the E-ring 382a, the protruding portion 342 is detected by the position sensor 343. Thus, the position sensors 313 and 343 can detect the positioning states of the developing roller 31 and the application roller 34 based on whether or not the protrusions 312 and 342 can be detected.

  In the second embodiment, similarly to the first embodiment, the application roller 34 and the developing roller 31 are designed so that play occurs in the thrust direction in consideration of manufacturing errors, assembling properties, and the like. It has become freely movable. Therefore, in the present embodiment, the second preliminary drive process shown in FIG. 8 is executed. Hereinafter, the second preliminary driving process will be described in detail.

a) Before Image Forming Operation In this embodiment, the developing roller 31 is not locked by the E-ring 382b at a predetermined locking position, and is more (+ X) than the predetermined locking position in the play in the thrust direction. Stops at a position close to the side. Also, the application roller 34 is not locked by the E ring 382a at a predetermined locking position, and stops at a position closer to the (−X) side than the predetermined locking position in the play in the thrust direction. (See FIG. 7A). In this state, the projection 312 can be detected by the position sensor 313, and the projection 342 cannot be detected by the position sensor 343. Therefore, based on the detection signals (position information) from these position sensors 313 and 343, the CPU 113 determines that the developing roller 31 and the application roller 34 are not positioned at predetermined locking positions. Can do. In this embodiment, the second image forming process shown in FIG. 8 is executed. Until a print command requesting execution of the developing operation is input from an external device such as a host computer via the interface 102. The CPU 113 enters a standby state (step S10).

b) During rotational drive operation When a print command is input from an external device such as a host computer via the interface 102, the CPU 113 gives a control command to the roller drive unit 118 to rotationally drive the application roller 34 and the developing roller 31 ( Step S20). At this time, the application roller 34 and the developing roller 31 rotate while being in contact with each other, so that thrust forces THar and THdr are generated in the application roller 34 and the developing roller 31, respectively. Therefore, the application roller 34 moves to the side where the thrust force THar is directed until it is locked at a predetermined locking position by the E-ring 382a. Further, the developing roller 31 moves to the side where the thrust force THdr is directed until it is locked at a predetermined locking position by the E-ring 382b.

  At this time, if the developing roller 31 is positioned at a predetermined position, the projection 312 cannot be detected by the position sensor 313, and it can be determined that the developing roller 31 has been positioned at the predetermined position. Further, when the application roller 34 is positioned at a predetermined position, the projection 342 can be detected by the position sensor 343, and it can be determined that the application roller 34 has been positioned at the predetermined position. As described above, the CPU 113 executes the rotation driving operation until it is determined that the application roller 34 and the developing roller 31 are positioned at predetermined positions (step S30). As described above, the position sensors 313 and 343 detect the positioning states of the developing roller 31 and the applying roller 34 to ensure that the applying roller 34 and the developing roller 31 are in their respective locking positions. (See FIG. 7B).

c) Image Forming Operation After it is determined that all the application rollers 34 and the developing rollers 31 have been positioned at predetermined positions, an image forming operation is executed (step S40). At this time, by the thrust forces THar and THdr generated on the application roller 34 and the developing roller 31, the application roller 34 and the development roller 31 are securely locked by the E-rings 382a and 382b at predetermined locking positions (FIG. 7 (c)).

  In this 2nd Embodiment, there can exist the following effects together with the effect in 1st Embodiment mentioned above. That is, it further includes position sensors 313 and 343 for detecting the positioning state of the developing roller 31 and the coating roller 34 in the thrust direction substantially orthogonal to the rotation direction D2, and the CPU 113 and the roller driving unit 118 detect the detection signals of the position sensors 313 and 343. The image forming operation is controlled based on (position information). Therefore, the positioning state of the developing roller 31 and the application roller 34 in the thrust direction can be detected in real time, and the timing for executing the image forming operation (development processing) can be controlled based on the detected position information. That is, it is detected in real time whether or not the developing roller 31 and the coating roller 34 are positioned at the predetermined locking position, and an image forming operation (immediately after the developing roller 31 and the coating roller 34 are positioned at the predetermined locking position ( Development processing) can be executed. Therefore, it is possible to prevent the rotation driving operation from being unnecessarily continued until the image forming operation (development processing) is executed, and the efficiency is high.

<Third Embodiment>
FIG. 9 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 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, as the “biasing member” of the present invention, a bias applying contact 38 b is provided on the developing roller 31, and a bias applying contact 38 a is provided on the application roller 341. 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 341. Further, an E-ring 383b as a “developer-bearing member positioning portion” according to the present invention and an E-ring 383a as a “coating roller positioning portion” according to the present invention are provided inside the tank 33Y. In the present embodiment, the first image forming process is executed. Other configurations are the same as those in the first embodiment. Hereinafter, the third embodiment will be described in detail with a focus 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 coating roller 341, a plurality of grooves 34a provided obliquely with respect to the rotation direction D2 of the coating roller 341 are formed as in 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 application contact 38 a that urges the application roller 341 in the same direction as the side to which the thrust force THar 2 generated in the application roller 341 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 THdr2 generated in the developing roller 31 faces is supported by the contact support member 381 (see FIG. 9).

  The bias applying contacts 38a and 38b are electrically connected to a coating bias generator (not shown) and a developing bias generator 114. Therefore, the application bias generation unit can apply the application bias to the application roller 341 via the bias application contact 38a, and the development bias generation unit 114 applies the development bias to the development roller 31 via the bias application contact 38b. Can do. Further, as shown in FIG. 9, the bias applying contacts 38a and 38b in the present embodiment are configured by leaf springs. Further, the biasing force BFar3 possessed by the bias applying contact 38a in the present embodiment is configured to be larger than the static frictional force acting between the developing roller 31 and the applying roller 341. On the other hand, the biasing force BFdr3 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 341. It is configured to be greater than the sum of power. Further, by applying a coating bias to the coating roller 341, the toner particles contained in the developer 32 carried on the coating roller 341 are moved to the surface layer side of the developer 32, and the coating roller 341 to the developing roller 31 are moved. The application efficiency of the developer 32 can be improved.

  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. 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. The E-ring 383a abuts against the inner wall of the tank 33Y, whereby 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 383a functions as the “coating roller positioning portion” of the present invention.

  By the way, in this embodiment, the application roller 341 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. For this reason, when an external force in the thrust direction is applied to the application roller 341 and the developing roller 31, it moves. In the present embodiment, the first image forming process shown in FIG. 6 is executed, which will be described in detail below.

a) Before Image Forming Operation The biasing force BFar3 applied to the application roller 341 by the bias applying contact 38a is larger than the static friction force acting between the developing roller 31 and the application roller 341. Therefore, the application roller 341 can be moved to the (−X) side by the biasing force BFar3 from the bias applying contact 38a until the E-ring 383a contacts the tank 33Y. The application roller 341 is locked at a predetermined position by the E ring 383a. The biasing force BFdr3 applied to the developing roller 31 by the bias applying contact 38b is a static friction force acting between the developing roller 31 and the photoconductor 11Y and a static force acting between the developing roller 31 and the coating roller 341. Greater than the sum of frictional forces. Therefore, the developing roller 31 can move to the (+ X) side by the biasing force BFdr3 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. 9A).

b) During rotational drive operation and image forming operation In response to a print command, the application roller 341 and the developing roller 31 rotate while being in contact with each other (rotational drive operation), and the thrust force THar2, THdr2 is generated. The side to which the thrust force THar2 generated in the application roller 341 faces is the same as the direction of the urging force BFar3. Therefore, the two forces of the thrust force THar2 and the urging force BFar3 act on the application roller 34, whereby the application roller 341 is more firmly locked by the E ring 383a. The direction to which the thrust force THdr2 generated in the developing roller 31 faces is the same as the direction of the biasing force BFdr3. Therefore, the two forces of the thrust force THdr2 and the urging force BFdr3 act on the developing roller 31, whereby the developing roller 31 is more firmly locked by the E-ring 383b (see FIG. 9B). Then, after the application roller 341 and the developing roller 31 are rotated a predetermined number of times, the image forming operation is executed.

c) Immediately after the end of the image forming operation As the application roller 341 and the developing roller 31 stop rotating, the thrust forces THar2 and THdr2 generated in the respective rollers disappear (FIG. 9C). However, a biasing force BFar3 is applied to the application roller 341 in the (-X) direction by the bias applying contact 38a, and the application roller 341 is locked by the E-ring 383a and does not move. Further, a biasing force BFdr3 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, the same direction as the direction in which the application roller 341 and the development roller 31 move relatively by the thrust forces THar2 and THdr2 generated by the application roller 341 and the development roller 31 rotating while being in contact with each other. In addition, bias applying contacts 38a and 38b (biasing members) having urging forces BFar3 and BFdr3 in a direction in which the application roller 341 and the developing roller 31 are relatively moved are provided. Therefore, during the rotational driving operation, the developing roller 31 and the application roller 341 are moved to a predetermined locking position in the thrust direction in a short time by the two forces of the thrust forces THdr2 and THar2 and the biasing contact biasing forces BFdr3 and BFar3. The E-rings 383b and 383a (positioning portions) can be locked. In this way, the developing roller 31 and the application roller 341 can be brought into a locked state at a predetermined locking position in a short time, so that the time until the image forming operation is executed can be shortened. In particular, in this embodiment, the urging force BFar3 is configured to be larger than the static friction force acting between the developing roller 31 and the application roller 341, and the urging force BFdr3 is equal to the developing roller 31 and the photosensitive member. 11 </ b> Y is configured to be larger than the sum of the static friction force acting between the developing roller 31 and the application roller 341. Therefore, both rollers 31 and 341 can be positioned at a predetermined locking position before the rotational driving operation is executed. In addition, by executing the rotational drive operation before executing the image forming operation, it is possible to more reliably place both rollers in a predetermined locking position.

<Fourth embodiment>
FIG. 10 is a flowchart showing a third image forming process in the fourth embodiment according to the present invention. The fourth embodiment is greatly different from the second embodiment in that the rotational driving speeds of the application roller 34 and the developing roller 31 are changed before and during the image forming operation. Other configurations are the same as those of the second embodiment. Hereinafter, the fourth embodiment will be described in detail focusing on differences from the second embodiment. In addition, about the structure and operation | movement same as 2nd Embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  The third image forming process in this embodiment will be described in detail with reference to FIG. In the third image forming process, the process waits until a print command is input (step S100). Then, after the printing command is input, the rotational driving operation of the coating roller 34 and the developing roller 31 is started at the first speed V1 (step S200). When the positioning of all the rollers 31, 34 is confirmed by the detection signals from the sensors 313, 343 (step S300), the rotational driving speeds of the coating roller 34 and the developing roller 31 are set to the second speed V2 (<V1). And shift. Then, after changing the rotational drive speed of both rollers 34 and 31, an image forming operation (development process) is started (step S500).

  In general, the higher the rotational drive speed of the developing roller 31 and the applying roller 34, the greater the thrust force generated in the developing roller 31 and the applying roller 34. In the fourth embodiment, until the developing roller 31 and the coating roller 34 are positioned at predetermined locking positions, the both rollers 31 are at the first speed V1 that is faster than the second speed V2 that is the optimum speed during the developing process. , 34 are driven to rotate. With such a configuration, the time until the developing roller 31 or the application roller 34 is positioned at a predetermined locking position can be shortened, so the time until the image forming operation (development processing) is performed is reduced. It can be shortened.

<Fifth Embodiment>
FIG. 11 is a flowchart showing a fourth image forming process according to the fifth embodiment of the present invention, and FIG. 12 is a view showing an example of a positional deviation correction process. The fourth embodiment is greatly different from the second embodiment in that a positional deviation correction process is executed instead of the image forming operation. Other configurations are the same as those of the second embodiment. Hereinafter, the fourth embodiment will be described in detail focusing on differences from the second embodiment. In addition, about the structure and operation | movement same as 2nd Embodiment, the description of the structure and operation | movement is abbreviate | omitted.

  Various known positional deviation correction processes can be applied as the positional deviation correction process in the present embodiment, and an example of the positional deviation correction process will be described in detail with reference to FIG. First, as shown in FIG. 12, for example, immediately after the apparatus is turned on, a normal image forming operation is performed on the intermediate transfer belt 41 in the order of yellow, magenta, cyan, and black in the order of registration marks YRM, MRM, CRM, and KRM. As a result, a toner image is formed. At this time, as image formation timing, control is performed so that registration marks YRM, MRM, CRM, and KRM are formed on the reference position S0. However, due to the assembly error of the apparatus, as shown in FIG. 12, in the light beam scanning direction X, errors Sm, Sc, Sk are generated from the reference position S0, and the registration marks MRM, CRM, KRM are changed. Sometimes formed. The errors Sm, Sc, Sk are measured by a sensor such as a CCD camera, and the image formation timing (scanning timing of the light beam 21) is changed so that the image position is shifted by the errors Sm, Sc, Sk. The error can be corrected and eliminated.

  Next, the fourth image forming process will be described in detail with reference to FIG. This fourth image forming process is executed when the apparatus is turned on (step S1000). After the apparatus is turned on, the rotation driving operation of the application roller 34 and the developing roller 31 is started (step S2000). Then, when the positioning of all the rollers 31 and 34 is confirmed by the detection signals from the sensors 313 and 343 (step S3000), for example, the above-described positional deviation correction processing is executed (step S4000).

  In the fifth embodiment, after the position of the developing roller 31 or the application roller 34 in the X direction is changed from an unstable state to a stable state (positioned to a predetermined locking position), the registration mark YRM is changed. , MRM, CRM, and KRM are formed on the intermediate transfer belt 41. As described above, since the process of correcting the positional deviation can be executed while the positions of the developing roller 31 and the application roller 34 in the X direction are stable, the correction accuracy of the correction process can be improved.

<Sixth Embodiment>
13 is a diagram showing an internal configuration of a printer in the sixth embodiment of the image forming apparatus according to the present invention, FIG. 14 is a block diagram showing an electrical configuration of the printer in FIG. 13, and FIG. 15 shows a fifth image forming process. A flowchart and FIG. 16 are time charts showing the start timing of the image forming operation. The sixth embodiment differs greatly from the above embodiment in that the present invention is applied to a so-called four-cycle image forming apparatus. In the present embodiment, the fifth image forming process is executed. Hereinafter, the sixth embodiment will be described in detail focusing on differences from the above embodiment. In addition, about the structure and operation | movement same as the said embodiment, the description of the structure and operation | movement is abbreviate | omitted. In this printer, when a print command 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 controls each part of the engine unit 1 in accordance with the control signal from the main control unit 100. By controlling, an image corresponding to the image signal is printed out on a recording medium such as a transfer sheet, a copy sheet, and an OHP sheet conveyed from a sheet feeding cassette disposed in the lower part of the apparatus main body. Further, in this engine unit 1, four cartridges are: (a) yellow developing cartridge 300Y; (b) magenta developing cartridge 300M; (c) cyan developing cartridge 300C; (d) black developing cartridge 300K. It is removable with respect to.

  The photoreceptor 1100 is rotatably mounted and rotates in the direction of the arrow in FIG. 13 (clockwise in FIG. 13). Further, a charging roller (not shown), a developing unit 300 (developing cartridges 300Y, 300M, 300C, and 300K) and a photosensitive member cleaning unit (not shown) are arranged around the photoconductor 1100 along the rotation direction. The The charging roller is in contact with the photoreceptor 1100 while being rotatably supported, and charges the surface of the photoreceptor 1100. Further, a cleaning blade (not shown) is provided on the upstream side of the charging roller in the rotation direction of the photoconductor 1100, and scrapes off the developer 32 remaining on the outer peripheral surface of the photoconductor 1100 after the primary transfer. In this way, the surface of the photoreceptor 1100 is cleaned.

  In this image forming apparatus, as shown in FIG. 13, laser light 21 is irradiated from the exposure unit 20 to the outer peripheral surface of the photoreceptor 1100 charged by the charging roller. The exposure unit 20 scans and exposes the laser beam 21 onto the photoconductor 1100 in accordance with an image signal from the engine control unit 110 to form an electrostatic latent image corresponding to the image signal on the photoconductor 1100 (latent image formation). processing).

  The electrostatic latent image formed in this way is developed by the liquid developer 32 carried on the developing roller 31 of one of the four developing cartridges, and the electrostatic latent image on the photoreceptor 1100 is made visible. (Development processing). Each developing roller 31 and application roller 34 are incorporated in a developing cartridge corresponding to each color. For example, the yellow developing cartridge 300Y includes a yellow developing roller 31, a yellow coating roller 34, and a yellow developer container 331. When the yellow developing cartridge 300Y is mounted at a predetermined position of the apparatus main body, engine control is performed. The yellow developing roller 31 can be controlled to be separated from and contacted with the photoreceptor 1100 by the unit 110.

  As shown in FIG. 14, each of the developing cartridges 300M to 300K is provided with memories 91 to 94 for storing data relating to the manufacturing lot and usage history of the developing cartridge, the remaining amount of the built-in toner, and the like. Furthermore, wireless communication devices 309Y, 309M, 309C, and 309K are provided in the developing cartridges 300M to 300K, respectively. Then, if necessary, these selectively communicate with the wireless communication device 109 provided on the main body side in a non-contact manner, and data is transmitted between the CPU 113 and the memories 91 to 94 via the interface 105. Various information such as consumable management for the developing cartridge is managed by sending and receiving. In this embodiment, non-contact data transmission / reception is performed using electromagnetic means such as wireless communication. However, a connector is provided on the main body side and each developing cartridge side, and the connector is mechanically fitted. By doing so, you may make it mutually transmit / receive data.

  The toner image developed by the developing unit 300 is primarily transferred onto the intermediate transfer belt 41 of the transfer unit 40 in the primary transfer region R1 located between the black developing roller 31 and the cleaning blade (transfer process), and is also suitable. The intermediate toner image transferred to the intermediate transfer belt 41 at a proper timing is secondarily transferred to the sheet. For example, when a color image is transferred to a sheet, the color toner images formed on the photoreceptor 1100 are superimposed on the intermediate transfer belt 41 to form a color image, and the sheet is taken out from a cassette or the like. It is conveyed to the next transfer area R2. A color image is secondarily transferred to this sheet to obtain a full color image. When transferring a monochrome image to a sheet, only the black toner image on the photoreceptor 1100 is formed on the intermediate transfer belt 41 and conveyed to the secondary transfer region R2 as in the case of a color image. Transfer to a sheet to obtain a monochrome image.

  The sheet on which the toner image has been transferred by the transfer unit 40 is conveyed to a fixing unit 60 mounted on the apparatus main body on the downstream side of the secondary transfer region R2 along a predetermined paper feed path (dashed line 5). Then, the toner image on the conveyed sheet is fixed on the sheet. The sheet is further conveyed along a paper feed path to a post-processing device (not shown) such as a discharge tray (not shown) or a multi-bin unit.

  Next, the fifth image forming process will be described in detail with reference to FIGS. 15 and 16. In the developing unit 300 as described above, due to problems such as manufacturing accuracy and assembly errors, the value of the magnitude of the thrust force generated when the developing roller 31 and the applying roller 34 are driven to rotate, the developing roller 31 and the applying roller The amount of play when 34 is attached to the apparatus usually varies for each developing cartridge 300Y, 300M, 300C, 300K. Therefore, by rotating the developing roller 31 and the coating roller 34, the rotational driving for rotating the developing roller 31 and the coating roller 34 required until the developing roller 31 or the coating roller 34 is positioned at a predetermined locking position. In many cases, the time varies depending on the developing cartridges 300Y to 300K. Therefore, in the present embodiment, the memories 91 to 94 (corresponding to the “storage means” of the present invention) included in each of the developing cartridges 300Y to 300K require the rotational drive time required for each developing cartridge, the amount of play in the X direction, and the like. Is stored in advance. For example, during the initialization operation when the apparatus is powered on, the rotation drive time information is read and stored in the main body memory 117, and used when the fifth image forming process is executed. I can do it.

  The fifth image forming process is executed when the apparatus is in a print standby state, and waits until a print command is input (step S10000). After the printing command is input to the apparatus, the rotation driving operation of all the application rollers 34 and the developing rollers 31 is started (step S20000, see FIG. 16). At this time, the rotation of all the application rollers 34 has an effect of stirring the developer 32 contained in each developer container 331 to bring it into an appropriate state. When the rotational drive operation is executed for a necessary time (step S30000), the image forming operation is executed (step S40000, see FIG. 16). The predetermined time in step S30000 is the longest time among the rotational drive times TY, TM, TC, and TK required for the developing cartridges 300Y to 300K stored in the memories 91 to 94. In this embodiment, the rotational drive time TC is used as a predetermined time. Further, in FIG. 16, only the latent image forming operation corresponding to the yellow (Y) component of the image to be formed is shown for simplicity of explanation, but in practice, magenta, cyan depending on the type of image. A latent image corresponding to the black component is formed.

  In the sixth embodiment, the timing for executing the image forming operation (development processing) is adjusted based on the necessary rotational drive time for each of the developing cartridges 300Y to 300K stored in the memories 91 to 94. That is, for all the developing cartridges 300Y to 300K, it is necessary to move the developing roller 31 or the coating roller 34 from the unstable position in the X direction (thrust direction) to the predetermined locking position. In addition, it is possible to know the time during which the developing roller 31 and the application roller 34 must be rotationally driven at a minimum. Then, after the developing roller 31 and the application roller 34 are rotationally driven for the necessary time, an image forming operation (developing process) is performed. Therefore, since the developing roller 31 and the application roller 34 are not driven to rotate more than necessary, the efficiency is high.

<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, although the present invention is applied to a color image forming apparatus using four color liquid developers, the application target of the present invention is not limited to this. In other words, the present invention is applicable to all image forming apparatuses that form a color image by superimposing a plurality of color toner images on a transfer medium such as a transfer belt, a transfer sheet, or a transfer drum.

  In the first to sixth embodiments, both the application rollers 34 and 341 and the development roller 31 are configured to have play in the thrust direction, and the positioning is performed on both the application rollers 34 and 341 and the development roller 31. Is provided. However, it may be configured such that play in the thrust direction occurs in one of the application rollers 34, 341 or the developing roller 31, and a positioning portion is provided only in the one roller. For example, when play is generated only in the application roller, an application roller positioning unit may be provided in each developing unit. With such a configuration, the application roller moving by the thrust force is locked at a predetermined application roller locking position in the thrust direction, and the application roller can be prevented from further moving from the locking position. it can. That is, the application roller is positioned at the application roller locking position. In this way, after all the application rollers are locked at the application roller locking position and positioned at the locking position, development processing is executed by each developing means. Accordingly, the movement of the application roller relative to the developer carrying member during the development process can be prevented, and the application pattern of the liquid developer applied to the developer carrying member can be prevented from being disturbed, so that the development accuracy is deteriorated. Can be prevented and development accuracy can be improved. In addition, by improving the development accuracy in this way, the quality of the formed color image can be improved by forming a color image by superimposing a plurality of color toner images with improved accuracy on a transfer medium. Can do.

  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. For example, it can be constituted by a coil spring, a rubber push, a leaf spring, or the like. In the third 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 disposed, but the roller drive motor is arranged. Of course, a configuration in which the application roller and the developing roller are urged from the provided one end may be used. In the third embodiment, a sensor may be used to confirm the positioning of the application roller and the development roller. In the fourth and fifth embodiments, the positioning of the application roller and the development roller is performed. The configuration in the first embodiment may be used. In other words, various methods can be used in combination as long as the developing process can be executed after the application roller and the developing roller have been positioned reliably.

  Further, in the above-described embodiment, the roller driving motor is provided for each of the coating roller and the developing roller. However, the rotational force of one roller driving motor is transmitted to two rollers using a gear, and the coating roller and the developing roller are transmitted. Of course, the developing roller may be rotationally driven.

  In addition, the positioning portion in the above embodiment may have any configuration as long as it can reliably lock the developer carrier or the application roller. For example, it can be configured by forming a flange portion on the rotating shaft of the roller, projecting a pin, or providing a disk.

  In the first to fifth embodiments, 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 is provided. A corresponding electrostatic latent image is formed. For example, by arranging one exposure unit and switching the irradiation direction of the laser beam using a mirror or the like, each of the photoreceptors 11Y, 11M, 11C, It is also possible to form an electrostatic latent image corresponding to each of 11K. 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 first to fifth embodiments, the regulation blade 35 performs trail regulation. However, the regulation blade 35 is disposed so that the tip of the regulation blade 35 faces the upstream side in the rotation direction of the application roller 34, so-called counter. Regulations may be made.

  The configuration in the sixth embodiment may be adopted in the first to fifth embodiments. In addition to the information described above, information stored in the storage unit includes necessary rotational drive speed and the like. Further, the rotational drive time required for positioning may change as the apparatus deteriorates with time. Therefore, the changed rotation drive time may be transmitted to the storage unit when the apparatus is turned off, and the information related to the rotation drive time stored in the storage unit may be updated. With such a configuration, the apparatus can be controlled based on the latest rotational drive time according to the state of the apparatus, so that the development process can be executed more efficiently.

  In the above embodiment, the image forming operation (“latent image forming process”, “developing process”, “transfer process”) is performed after the positioning of the developer carrier and the application roller is completed. Of course, “development processing” in the present invention may be executed after the “latent image forming process” is started during execution of the “process” and the “latching step” in the present invention is completed. Even with such a configuration, the same effects as those of the above-described embodiment can be achieved.

  In the above embodiment, a printer that prints an image provided 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, 1100 ... Photosensitive body (latent image carrier), 115 ... Transfer bias generating part (transfer means), 31 ... Developing roller (developer carrier), 32 ... Developer (liquid developer), 34, 341 ... Coating Roller (anilox roller), 313, 343 ... position sensor (position detecting means), 38a, 38b ... bias applying contact (biasing member), 382a, 382b, 383a, 383b ... E-ring (positioning part), 53Y, 53M , 53C, 53K ... primary transfer roller (transfer means), D2 ... first direction, BFar3, BFdr3 ... urging force, THdr, THdr2, THar, THar2 ... thrust force, X ... thrust direction

Claims (11)

A plurality of developing units each storing liquid developers of different colors and performing a developing process using the liquid developers to form a toner image, and a toner formed by each of the plurality of developing units An image forming apparatus comprising: a transfer unit that transfers an image to a transfer medium; and a control unit that controls execution timing of the development processing by each of the plurality of development units.
Each of the plurality of developing means is
A developer carrying member that rotates and carries the liquid developer stored in the developing means to the developing position for carrying out the developing process by carrying it while carrying the developer on its outer peripheral surface;
A plurality of grooves are provided on the surface of the groove so as to be rotatable in the first direction, and the liquid developer stored in the developing means is provided in the groove. An application roller that conveys the liquid developer onto the developer carrier while carrying the developer to the developer carrier;
A developer carrier positioning portion for locking the developer carrier at a predetermined developer carrier locking position in a thrust direction substantially perpendicular to the first direction;
The control means rotationally drives the developer carrier and the application roller, and all the developer carriers are locked by the developer carrier positioning portion at the developer carrier locking position. An image forming apparatus that executes the development processing later. Each of the plurality of developing units further includes a coating roller positioning portion that locks the coating roller at a predetermined coating roller locking position in the thrust direction.
The control means rotates the developer carrier and the application roller, and executes the development process after all the application rollers are locked by the application roller positioning portion at the application roller locking position. The image forming apparatus according to claim 1. A plurality of developing units each storing liquid developers of different colors and performing a developing process using the liquid developers to form a toner image, and a toner formed by each of the plurality of developing units An image forming apparatus comprising: a transfer unit that transfers an image to a transfer medium; and a control unit that controls execution timing of the development processing by each of the plurality of development units.
Each of the plurality of developing means is
A developer carrying member that rotates and carries the liquid developer stored in the developing means to the developing position for carrying out the developing process by carrying it while carrying the developer on its outer peripheral surface;
A plurality of grooves are provided on the surface of the groove so as to be rotatable in the first direction, and the liquid developer stored in the developing means is provided in the groove. An application roller that conveys the liquid developer onto the developer carrier while carrying the developer to the developer carrier;
A coating roller positioning portion for locking the coating roller at a predetermined coating roller locking position in a thrust direction substantially orthogonal to the first direction;
The control means rotates the developer carrier and the application roller, and executes the development process after all the application rollers are locked by the application roller positioning portion at the application roller locking position. An image forming apparatus.   4. The image forming apparatus according to claim 1, wherein each of the plurality of developing units forms a registration mark for correcting a relative positional shift in the plurality of colors as the toner image. 5. In each of the plurality of developing means, rotation required from the start of rotation of the developer carrier and the application roller until at least one of the developer carrier and the application roller is positioned at a predetermined locking position. It further comprises storage means for storing drive time,
5. The image forming apparatus according to claim 1, wherein the control unit adjusts a timing of executing the development processing based on the rotation driving time stored in the storage unit.   The control means rotates the developer carrier and the coating roller until at least one of the developer carrier and the coating roller is positioned at a predetermined locking position for each of the plurality of developing units. The image forming apparatus according to claim 1, wherein a driving speed is set to a speed higher than the rotational driving speed at the time of the developing process.   Each of the plurality of developing units has a direction in which the application roller and the developer carrier are relatively moved by a thrust force generated when the application roller and the developer carrier are rotated while being in contact with each other. 7. The image forming apparatus according to claim 1, further comprising a biasing member having a biasing force in a direction in which the application roller and the developer carrying member are relatively moved in the same direction. Each of the plurality of developing means further comprises position detecting means for detecting a positioning state of the developer carrier and the application roller in a thrust direction substantially orthogonal to the first direction,
The image forming apparatus according to claim 1, wherein the control unit controls execution timing of the development processing based on position information from the position detection unit.   9. The application roller according to claim 1, wherein the coating roller is an anilox roller having the groove formed on the surface thereof, and transports the liquid developer by carrying the liquid developer in the groove. Image forming apparatus. A plurality of developing units each storing liquid developers of different colors and performing a developing process using the liquid developers to form a toner image, and a toner formed by each of the plurality of developing units The image forming apparatus includes a transfer unit that transfers an image to a transfer medium, and a control unit that controls execution timing of development processing by each of the plurality of development units, and each of the plurality of development units is stored in the development unit. A developer carrying member that rotates while carrying a liquid developer on its outer peripheral surface and transports it to the development position for carrying out the development treatment and performs the development treatment, and is provided rotatably in the first direction. The surface has a plurality of grooves provided obliquely with respect to the first direction, and transports the liquid developer stored in the developing means to the developer carrier while supporting the liquid developer in the grooves. The liquid A coating roller for applying the developer onto the developer carrier, and positioning for the developer carrier for locking the developer carrier at a predetermined developer carrier locking position in a thrust direction substantially orthogonal to the first direction. An image forming apparatus comprising:
In each of the plurality of developing means, rotating the developer carrier and the application roller to move the developer carrier in the thrust direction toward the developer carrier positioning portion;
In each of the plurality of developing means, the step of locking the developer carrier at the developer carrier locking position;
And a step of executing the development processing operation after all the developer carriers are locked at the developer carrier locking position. A plurality of developing units each storing liquid developers of different colors and performing a developing process using the liquid developers to form a toner image, and a toner formed by each of the plurality of developing units The image forming apparatus includes a transfer unit that transfers an image to a transfer medium, and a control unit that controls execution timing of development processing by each of the plurality of development units, and each of the plurality of development units is stored in the development unit. A developer carrying member that rotates while carrying a liquid developer on its outer peripheral surface and transports it to the development position for carrying out the development treatment and performs the development treatment, and is provided rotatably in the first direction. The surface has a plurality of grooves provided obliquely with respect to the first direction, and transports the liquid developer stored in the developing means to the developer carrier while supporting the liquid developer in the grooves. The liquid An image is provided with an application roller for applying an agent to the developer carrier, and an application roller positioning portion for locking the application roller at a predetermined application roller locking position in a thrust direction substantially orthogonal to the first direction. In the forming device,
In each of the plurality of developing means, rotationally driving the developer carrier and the application roller to move the application roller toward the application roller positioning portion in a thrust direction;
Locking each of the application rollers at the application roller locking position in each of the plurality of developing units;
And a step of executing the developing process after all the application rollers are locked at the application roller locking position.

Images