JP2013246337A - Liquid developing device and wet image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of a developer attributed to friction heat.SOLUTION: A liquid developing device 6 develops with a developer including a carrier liquid and toner, electrostatic latent images included in image part areas P1, P2, successively formed on an image carrier 5 with an image interval area Q1. The liquid developing device 6 comprises: a developing roller 17 which has a surface 17S to which the developer is supplied, and conveys the developer to a developing position DP opposite to the image carrier 5; a supply roller 16 which has a surface 16S, and supplies the developer to the surface 17S; and a driving mechanism 20. The driving mechanism 20 brings the surfaces 17S and 16S into contact to each other when the surface 16s is opposite to first opposite expected parts S1, S2 of the surface 17S opposite to the image part areas P1, P2, and brings the surfaces 17S and 16S into separation from each other at a prescribed timing when the surface 16S is opposite to second opposite expected parts T1, T2 of the surface 17S opposite to the image interval areas Q1, Q2.

Description

  The present invention relates to a liquid developing apparatus and a wet image forming apparatus, and in particular, a liquid developing apparatus that develops an electrostatic latent image formed on an image carrier using a developer containing a carrier liquid and a toner, and its The present invention relates to a wet image forming apparatus including a liquid developing device.

  Japanese Patent Laying-Open No. 2006-011292 (Patent Document 1) discloses an invention relating to a liquid developing device. In this liquid developing device, the temperature of the liquid developer is detected, and the gap between the application roller and the pumping roller is adjusted according to the detection result. This publication states that according to this liquid developing apparatus, an appropriate amount of liquid developer can be transferred to the developing roller through the application roller.

  Japanese Patent Laying-Open No. 2009-186748 (Patent Document 2) discloses an invention related to a developing device. The developing device includes a developer carrier and a developer carrier abutting member. The developer carrier contact member reduces the contact pressure with the developer carrier during non-image formation. This publication states that according to this developing device, the thickness of the thin layer formed by the liquid developer can be properly controlled without being adversely affected by temperature fluctuations.

  Japanese Patent Laid-Open No. 10-268646 (Patent Document 3) discloses an invention relating to a wet developing apparatus. In this wet developing apparatus, the developing roller includes a heat pipe. A cooling fin is fixed to the developing roller shaft. The developer is cooled by a developing roller having a heat pipe structure. The publication states that the photoreceptor can be directly cooled using the cooled developer.

  Japanese Patent Laying-Open No. 2004-012710 (Patent Document 4) discloses an invention relating to a liquid developing electrophotographic apparatus. The developing device used in the liquid developing electrophotographic apparatus includes a temperature adjusting device and a temperature sensor that measures the temperature of the liquid toner on the developing roller. The publication states that the temperature of the liquid toner can be kept constant by feeding back the temperature data of the temperature sensor.

  Japanese Patent Laying-Open No. 2006-208673 (Patent Document 5) discloses an invention related to an image forming apparatus. In this image forming apparatus, a cooling duct is used. This publication states that according to this image forming apparatus, the developing roller and the photoreceptor can be cooled to prevent the deterioration of the image quality.

  Japanese Patent Laying-Open No. 2010-271412 (Patent Document 6) discloses an invention relating to a wet image forming apparatus. This wet image forming apparatus includes a cooling mechanism for cooling the developing member. This publication states that according to the wet image forming apparatus, the developing roller can be efficiently cooled.

JP 2006-011292 A JP 2009-186748 A Japanese Patent Laid-Open No. 10-268646 JP 2004-012710 A JP 2006-208673 A JP 2010-271412 A

  A liquid developing device used in a wet image forming apparatus includes a developing roller and a supply roller. The developer on the supply roller is supplied to the development roller through the contact portion in a state where the supply roller and the development roller are in contact with each other. The developer carried on the developing roller is used to develop the electrostatic latent image on the photoreceptor.

  When the moving speed of the surface of the developing roller and the moving speed of the surface of the supply roller are different from each other, frictional heat is generated at the contact portion between the developing roller and the supply roller. When the frictional heat is generated, the developer is heated to raise the temperature of the developer, and the deterioration of the developer is promoted.

  An object of the present invention is to provide a liquid developing device capable of suppressing the deterioration of the developer and a wet image forming apparatus including the liquid developing device.

  The liquid developing device according to the present invention is a developer containing a carrier liquid and a toner containing an electrostatic latent image contained in a plurality of image area regions continuously formed on an image carrier while leaving a space between images. A liquid developing device that develops using the toner, having a first surface to which the developer is supplied, and transporting the developer to a development position facing the image carrier by movement of the first surface. The developer carrying member has a second surface whose moving speed is different from the moving speed of the first surface, and the developer is applied to the first surface in a state where the second surface is in contact with the first surface. A developer supply body to be supplied; and a drive mechanism for separating and abutting the first surface and the second surface, wherein the drive mechanism is the first of the first surfaces of the developer carrier. The developer is supplied to the first opposed portion facing the image area. When the second surface of the developer is opposed to each other, the first surface and the second surface are brought into contact with each other, and a second facing that faces the inter-image region on the first surface of the developer carrier. The first surface and the second surface are separated from each other at a predetermined timing when the second surface of the developer supply body faces a predetermined portion.

  Preferably, the first surface of the developer carrier and the second surface of the developer supply body move in opposite directions.

  Preferably, the liquid developing apparatus according to the present invention further includes another developer supply body that contacts the developer supply body and supplies the developer to the developer supply body.

  The wet image forming apparatus according to the present invention includes an image carrier, an image forming mechanism for forming an electrostatic latent image on the image carrier, and the electrostatic image formed on the image carrier by the image forming mechanism. The liquid developing device according to the present invention for developing a latent image.

  According to the present invention, it is possible to obtain a liquid developing apparatus capable of suppressing the deterioration of the developer and a wet image forming apparatus including the liquid developing apparatus.

1 is a diagram schematically showing a wet image forming apparatus according to Embodiment 1. FIG. FIG. 1 is an enlarged view of a liquid developing device and the like in Embodiment 1 (a supply roller is in contact with a developing roller). FIG. 6 is a diagram illustrating a state in which a driving mechanism used in the liquid developing device according to Embodiment 1 causes a supply roller to contact the developing roller. FIG. 6 is a diagram illustrating a state where a driving mechanism used in the liquid developing device in Embodiment 1 separates a supply roller from a developing roller. FIG. 2 is an enlarged view of the liquid developing device and the like in Embodiment 1 (the supply roller is separated from the developing roller). FIG. 6 is a first diagram for explaining a control operation for a drive mechanism of a control unit used in the liquid developing device in Embodiment 1 (a supply roller is in contact with the developing roller); FIG. 6 is a second diagram for explaining a control operation for a drive mechanism of a control unit used in the liquid developing device in Embodiment 1 (a supply roller is separated from the development roller). FIG. 3 is a diagram illustrating a control block relating to a drive mechanism and a control unit used in the liquid developing device in the first embodiment. FIG. 6 is a flowchart showing the operation of a control unit and the like used in the liquid developing device in the first embodiment. (A) shows the change with time of the developer amount on the developing roller located immediately downstream of the nip portion formed between the supply roller and the developing roller used in the liquid developing device in the first embodiment. FIG. (B) is a figure which shows a time-dependent change of the distance (distance between axes) between the rotating shaft of the supply roller used for the liquid developing device in Embodiment 1, and the rotating shaft of a developing roller. FIG. 5 is a diagram illustrating a liquid developing device in a second embodiment. FIG. 10 is an enlarged view of a liquid developing device and the like in Embodiment 3 (a supply roller is in contact with a developing roller). FIG. 10 is an enlarged view of the liquid developing device and the like in Embodiment 3 (the supply roller is separated from the developing roller). FIG. 10 is an enlarged view of a liquid developing device and the like in Embodiment 4 (a supply roller is in contact with a developing roller). FIG. 10 is an enlarged view of a liquid developing device and the like in Embodiment 4 (the supply roller is separated from the developing roller).

  Embodiments based on the present invention will be described below with reference to the drawings. In the description of each embodiment, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, the amount, and the like unless otherwise specified. In the description of each embodiment, the same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated.

[Embodiment 1]
(Wet image forming apparatus 100)
FIG. 1 is a diagram schematically showing a wet image forming apparatus 100 in the present embodiment. As shown in FIG. 1, the wet image forming apparatus 100 includes a paper feeding device 1, a paper transport path 2, a transfer roller 3, an intermediate transfer member 4, a photosensitive member 5 (image carrier), a liquid developing device 6, and a cleaning device 7. A latent image erasing device 8, a charging device 9, an exposure device 10, a cleaning device 11, a fixing device 12, and a paper discharge device 13.

  Various types of printing paper including sheet or continuous paper are stored in the paper feeding device 1. The sheet conveyance path 2 is formed between the transfer roller 3 and the intermediate transfer body 4. The printing paper is sent from the paper feeding device 1 to the paper transport path 2 by a paper feeding mechanism (not shown) provided in the paper feeding device 1. Four photoconductors 5 are provided around the intermediate transfer member 4 rotating in the direction of arrow a. One liquid developing device 6 is provided so as to correspond to one photoconductor 5.

  When forming a color image on a printing paper, the photosensitive member 5 and the liquid developing device 6 are required as many as the number of developers prepared to correspond to the color image. In the present embodiment, four color developers are used. The wet image forming apparatus 100 includes four photosensitive members 5 and four liquid developing devices 6. The four colors are, for example, cyan, magenta, yellow, and black. The arrangement order of the photoreceptor 5 and the liquid developing device 6 corresponding to cyan, magenta, yellow, and black is not particularly limited.

  The photoreceptor 5 rotates in the direction of arrow b. Around the photoconductor 5, along the rotation direction of the photoconductor 5, a cleaning device 7, a latent image erasing device 8, a charging device 9, an exposure device 10 (image forming mechanism), a liquid developing device 6, and an intermediate transfer The body 4 is arranged in order. The developer or the like remaining on the photoconductor 5 is removed from the photoconductor 5 by the cleaning device 7. The latent image remaining on the photoreceptor 5 is erased by the latent image erasing device 8.

  The surface of the photoreceptor 5 is uniformly charged by the charging device 9. The exposure apparatus 10 irradiates the surface of the photoconductor 5 with light based on predetermined image information. An electrostatic latent image based on predetermined image information is formed on the surface of the photoreceptor 5. The electrostatic latent image is conveyed toward the developing position (see the developing position DP in FIG. 2) by the rotation of the photosensitive member 5. The liquid developing device 6 conveys a developer (a liquid developer containing a carrier liquid and toner) to a development position that faces the photoreceptor 5. The liquid developing device 6 develops the electrostatic latent image formed on the photoreceptor 5 using a developer. By developing the electrostatic latent image, a toner image is formed on the photoreceptor 5.

  The intermediate transfer member 4 is disposed in contact with the photosensitive member 5. An electric field is formed between the intermediate transfer member 4 and the photosensitive member 5 by a voltage application device (not shown). The toner image on the photoconductor 5 is transferred onto the intermediate transfer body 4 by the action of this electric field. The toner images formed on each of the four photoconductors 5 are sequentially transferred onto the intermediate transfer member 4 and are superimposed on the intermediate transfer member 4. A toner image or the like remaining on the photoconductor 5 after the transfer is removed from the photoconductor 5 by the cleaning device 7.

  The transfer roller 3 is disposed so as to face the intermediate transfer body 4. The printing paper sent out from the paper feeding device 1 to the paper transport path 2 passes between the transfer roller 3 and the intermediate transfer body 4. An electric field is formed between the intermediate transfer body 4 and the transfer roller 3 by a voltage application device (not shown). By the action of this electric field, the toner image on the intermediate transfer body 4 is transferred onto the printing paper. The toner image remaining on the intermediate transfer body 4 after the transfer is removed from the intermediate transfer body 4 by the cleaning device 11.

  The toner image transferred onto the printing paper is heated and pressurized by the fixing device 12 and is fixed on the printing paper as an image. The printing paper on which the image is formed on the front surface is conveyed to the paper discharge device 13 and is discharged from the paper discharge device 13 as an output product. In the present embodiment, the toner images are superimposed on the intermediate transfer member 4, but a configuration in which the toner images are superimposed on the photosensitive member 5 may be employed, or the toner images may be superimposed on the printing paper. A configuration may be employed. When these configurations are employed, the intermediate transfer member 4 may be provided as necessary.

(Liquid developing device 6)
With reference to FIG. 2, the liquid developing device 6 in the present embodiment will be described in detail. The liquid developing device 6 includes a developer tank 14 for storing a developer 14W, a pumping roller 15 (another developer supply body), a supply roller 16 (developer supply body), a development roller 17 (developer carrier), a charge A device 18, a cleaning device 19, and a drive mechanism 20 are included. As described above, the developer 14W includes a carrier liquid and toner.

  For convenience of illustration, the drive mechanism 20 is schematically illustrated in FIG. 2 using dotted lines. Details of the drive mechanism 20 will be described later with reference to FIGS. 3 and 4. The pumping roller 15, the supply roller 16, and the developing roller 17 in the present embodiment are composed of roller-shaped members, but these may be composed of belt-shaped members.

  The developer tank 14 is supplied with a developer 14W from a developer supply device (not shown). The pumping roller 15 is composed of, for example, an anilox roller. The pumping roller 15 may be composed of a metal roller having a smooth surface, or may be composed of a roller having a rubber or resin layer provided on the surface. A part of the pumping roller 15 is immersed in the developer 14W. The developer 14 </ b> W is pumped onto the surface of the pumping roller 15 by the pumping roller 15 rotating in the direction of arrow e.

  The supply roller 16 is arranged so as to rotate in the direction of the arrow d and contact the pumping roller 15. The supply roller 16 is composed of a metal roller having a smooth surface. The supply roller 16 may be composed of a roller having a rubber or resin layer provided on the surface. The developer carried on the drawing roller 15 is transferred from the drawing roller 15 to the surface of the supply roller 16 at a contact portion between the drawing roller 15 and the supply roller 16.

  Although the details will be described later, the supply roller 16 contacts the developing roller 17 or is separated from the developing roller 17. This operation is realized by the drive mechanism 20.

  If the friction between the pumping roller 15 and the supply roller 16 is large, heat is generated by the friction. The frictional heat heats the developer and causes the developer to deteriorate. Therefore, it is desirable that the material of the roller used for the pumping roller 15 and the material of the roller used for the supply roller 16 are combined so that frictional heat is not easily generated between them.

  Furthermore, it is desirable that the ratio between the rotation speed of the pumping roller 15 and the rotation speed of the supply roller 16 is set to a value such that frictional heat is not easily generated between them. For example, the pumping roller 15 and the supply roller 16 may rotate at a rotational speed such that there is no difference in the moving speed of the surfaces of the rollers at the contact portion between the pumping roller 15 and the supply roller 16. The pumping roller 15 may not be provided with a rotation driving mechanism, but may be configured such that only the supply roller 16 is provided with a rotation driving mechanism so that the pumping roller 15 is driven to rotate as the supply roller 16 rotates.

  The developing roller 17 rotates in the direction of arrow c. The moving speed of the surface 17S (first surface) of the developing roller 17 is different from the moving speed of the surface 16S (second surface) of the supply roller 16. The developing roller 17 and the supply roller 16 in the present embodiment are configured such that the surface 17S of the developing roller 17 and the surface 16S of the supply roller 16 move in opposite directions at the contact portion (supply position SP) between them. Rotate (counter rotation).

  As the developing roller 17, a roller having a rubber or resin layer provided on the surface of a metal roller and configured to have an appropriate frictional resistance is used. At the contact portion (supply position SP) between the surface 17S of the developing roller 17 and the surface 16S of the supply roller 16, the developer is supplied from the surface 16S of the supply roller 16 to the surface 17S of the development roller 17.

  More specifically, the developer carried on the surface 16 </ b> S of the supply roller 16 is conveyed toward the supply position SP by the rotation of the supply roller 16. At the supply position SP, the developer is supplied from the surface 16S of the supply roller 16 to the surface 17S of the development roller 17 with the surface 16S of the supply roller 16 in contact with the surface 17S of the development roller 17. The surface 17S of the developing roller 17 carries an appropriate amount of developer as a layer having a uniform thickness.

  The charging device 18 is upstream of the contact portion (development position DP) between the developing roller 17 and the photosensitive member 5 in the rotating direction (arrow c direction) of the developing roller 17, and the developing roller 17 rotates. It arrange | positions in the position downstream from the contact part (supply position SP) of the developing roller 17 and the supply roller 16 in a direction (arrow c direction). The developer (a thin layer of developer) held on the developing roller 17 is charged by the charging device 18. The charged developer is conveyed toward the developing position DP where the developing roller 17 faces the photoconductor 5 by the rotation of the developing roller 17.

  The developing roller 17 is disposed so as to contact the photoreceptor 5. An electric field is formed between the developing roller 17 and the photoreceptor 5 by a voltage application device (not shown). The developer conveyed to the development position DP moves toward the electrostatic latent image on the photoconductor 5 by the action of this electric field, and develops the electrostatic latent image. The developer remaining on the developing roller 17 after development is removed from the surface of the developing roller 17 by the cleaning device 19.

(Drive mechanism 20)
FIG. 3 is a diagram showing a driving mechanism 20 used in the liquid developing device 6 of the present embodiment. As described above, the drive mechanism 20 brings the supply roller 16 into contact with the developing roller 17 and causes the supply roller 16 to be separated from the developing roller 17 (supply position SP). In FIG. 3, a state in which the drive mechanism 20 causes the supply roller 16 to contact the developing roller 17 is illustrated. The surface 16S of the supply roller 16 is located at the supply position SP.

  The drive mechanism 20 according to the present embodiment includes an arm 21, a gear 22, a drive motor 23, a gear 24, a control unit 30, and a spring 40. The gear 22 is fixed to the lower end of the arm 21. The arm 21 rotates integrally with the gear 22 with the lower end of the arm 21 as the center of rotation. The upper end of the arm 21 supports the rotation shaft of the supply roller 16. A gear 24 meshes with the gear 22. The gear 24 is rotated by the drive motor 23. The drive motor 23 is driven and controlled by the control unit 30.

  In the state shown in FIG. 3, the spring 40 provided on the upper portion of the arm 21 brings the supply roller 16 into contact (pressure contact) with the developing roller 17 with a predetermined urging force. Frictional heat is generated at the contact portion (supply position SP) between the supply roller 16 and the developing roller 17. In the state shown in FIG. 3, the developer 14 </ b> W stored in the developer tank 14 is supplied to the developing roller 17 through the scooping roller 15 and the supply roller 16.

  The developer is conveyed toward the developing position DP where the developing roller 17 faces the photoreceptor 5 by the rotation of the developing roller 17. When a predetermined control signal is input to the control unit 30 in this state, the control unit 30 drives the drive motor 23 to rotate the gear 24 in the direction indicated by the arrow DR in FIG.

  Referring to FIG. 4, when gear 24 rotates in the direction of arrow DR, gear 22 rotates integrally with arm 21. The arm 21 rotates against the urging force of the spring 40. The supply roller 16 supported on the upper end of the arm 21 moves in the arrow AR direction. The supply roller 16 is separated from the developing roller 17 (supply position SP).

  As shown in FIG. 5, the developer 14 </ b> W stored in the developer tank 14 is not supplied to the developing roller 17 when the supply roller 16 is separated from the developing roller 17 (supply position SP). The supply roller 16 and the developing roller 17 are separated from each other, and no frictional heat is generated between them. The drive mechanism 20 of the present embodiment uses the operation as described above to bring the supply roller 16 into contact with the developing roller 17 or to separate the supply roller 16 from the developing roller 17.

  With reference to FIG. 6 and FIG. 7, the control operation with respect to the drive mechanism 20 of the control unit 30 will be described. As shown in FIG. 6, when the wet image forming apparatus 100 (see FIG. 1) according to the present embodiment is operated so as to continuously form images on printing paper, the surface of the photoreceptor 5. In 5S, an image part region P1, an inter-image region Q1, an image part region P2, and an inter-image region Q2 are continuously formed. An electrostatic latent image based on a predetermined image signal is formed in the image area P1 and P2. The inter-image areas Q1 and Q2 are areas not used for image formation on the printing paper (in other words, areas other than the image area P1 and P2).

  For example, when the printing paper to be printed is a plurality of sheets, the image area P1 corresponds to an image formed on one printing paper, and the image area P2 is the next one. It corresponds to an image formed on one printing sheet. The inter-image region Q1 is a portion corresponding to between the printing paper and the next printing paper, and is an area where no image is formed. The inter-image area Q2 is a portion corresponding to the area between the next printing paper and the next printing paper, and is an area where no image is formed.

  In the present embodiment, image portion areas P1, P2 and inter-image areas Q1, Q2 are formed so as to correspond to two sheets. When the printing paper to be printed is a large number of sheets, the image area is continuously formed on the surface 5S of the photoconductor 5 by the same number as the number of sheets, and the inter-image area is adjacent to each other. Formed between matching image area.

  When the printing paper to be printed is continuous paper, the image area P1 corresponds to an image formed in a predetermined area located upstream of the continuous paper, and the image area P2 It corresponds to an image formed in another predetermined area located downstream of the continuous paper. The wet image forming apparatus 100 vacates the inter-image region even when an image is continuously formed on each of a plurality of sheets or even when an image is continuously formed on continuous paper. However, an image area is continuously formed on the surface 5S of the photosensitive member 5.

  In FIG. 6, an image area and an inter-image area are formed on a part of the surface 5S of the photoconductor 5, but the circumferential width of the image area corresponds to the width of the image formed on the printing paper. And can be changed arbitrarily. The width in the circumferential direction of the inter-image region can also be arbitrarily changed according to the size of the printing paper or the specifications of the wet image forming apparatus. Accordingly, the positions of the image portion area and the inter-image area may be displaced with time with respect to the upstream side or the downstream side every time the photosensitive member 5 rotates.

  As described above, the developing roller 17 and the photosensitive member 5 rotate so that the surface 17S of the developing roller 17 faces the surface 5S of the photosensitive member 5, respectively. A part of the surface 17S of the developing roller 17 (first counter-scheduled portion S1) faces the image area P1 in the surface 5S of the photoreceptor 5. The circumferential width of the first opposed portion S1 corresponds to the circumferential width of the image area P1. A part of the surface 17S of the developing roller 17 (second opposed portion T1) faces the inter-image region Q1 in the surface 5S of the photoreceptor 5 (scheduled to face). The circumferential width of the second opposing portion T1 corresponds to the circumferential width of the inter-image region Q1.

  Similarly, a part of the surface 17S of the developing roller 17 (first counter-scheduled portion S2) is opposed to the image area P2 in the surface 5S of the photoreceptor 5 (scheduled to be opposed). The circumferential width of the first opposed portion S2 corresponds to the circumferential width of the image area P2. A part of the surface 17S of the developing roller 17 (second opposed portion T2) faces the inter-image region Q2 in the surface 5S of the photoreceptor 5 (scheduled to face). The circumferential width of the second opposing portion T2 corresponds to the circumferential width of the inter-image region Q2.

  The developer carried on the first opposed portion S <b> 1 of the developing roller 17 is used for developing the electrostatic latent image formed in the image area P <b> 1 of the photoreceptor 5. The developer carried on the first opposed portion S <b> 2 of the developing roller 17 is used to develop the electrostatic latent image formed in the image area P <b> 2 of the photoconductor 5.

  On the other hand, even if the developer is carried on the second facing portion T1 of the developing roller 17, the developer carried on the second facing portion T1 is expected to face the inter-image region Q1. Therefore, it is not used for developing the electrostatic latent image in the image area P1, P2. In other words, the developer carried on the second oppositely-scheduled portion T1 is not used for image formation of printing paper on which images are continuously formed.

  Similarly, even if the developer is carried on the second opposed portion T2 of the developing roller 17, the developer carried on the second opposed portion T2 is expected to face the inter-image region Q2. Therefore, it is not used for developing the electrostatic latent image in the image area P1, P2. In other words, the developer carried on the second oppositely-scheduled portion T2 is not used for image formation of printing paper on which images are continuously formed.

  As described above, in wet image forming apparatus 100 (see FIG. 1) of the present embodiment, control unit 30 controls drive mechanism 20. When the surface 16S of the supply roller 16 is opposed to the first opposed portions S1 and S2, the drive mechanism 20 arranges the surface 16S of the supply roller 16 at the supply position SP, and the surface 16S of the supply roller 16 is developed to the developing roller. 17 is brought into contact (pressure contact) with the surface 17S. The developer is supplied from the supply roller 16 to the first opposed portions S1 and S2.

  Referring to FIG. 7, on the other hand, when the surface 16S of the supply roller 16 is opposed to the second opposed scheduled portions T1 and T2 (in other words, the second opposed scheduled portions T1 and T2 are supplied) When positioned at the position SP), the surface 16S of the supply roller 16 is separated from the surface 17S of the developing roller 17 (supply position SP). By this operation, the developer is not supplied from the supply roller 16 to the second oppositely scheduled portions T1 and T2. As described above, the inter-image areas Q1 and Q2 that are scheduled to face the second opposed portions T1 and T2 are not used for image formation. Therefore, even if the developer is not supplied to the second opposed portions T1, T2, the wet image forming apparatus 100 (see FIG. 1) uses the developer supplied to the first opposed portions S1, S2. Necessary images can be continuously formed on the printing paper.

  FIG. 8 is a diagram illustrating control blocks related to the drive mechanism 20 and the control unit 30. Referring to FIG. 8, a rotation position detector 31 is provided on the developing roller 17 (developer carrier). The rotation position detection unit 31 reads the rotation position (rotation angle) of the developing roller 17 and sends the information to the control unit 30. The control unit 30 controls the drive mechanism 20 based on the information received from the rotational position detection unit 31.

  With reference to FIG. 8 and FIG. 9, the operation | movement flowchart of the control part 30 which controls the drive mechanism 20 is demonstrated in detail. First, a signal for starting continuous printing is input from the outside to the control unit 30. The control unit 30 controls the drive mechanism 20, and the drive mechanism 20 brings the supply roller 16 into contact with the developing roller 17 (step ST1).

  The control unit 30 detects the rotation position of the developing roller 17 using the rotation position detection unit 31 (step ST2). Based on the information about the rotational position of the developing roller 17 acquired from the rotational position detecting unit 31, the control unit 30 causes the first opposed portion (S 1, S 2) on the developing roller 17 to be in contact with the supply roller 16 ( The number of passes through the supply position SP) is counted.

  Until the first scheduled portion on the developing roller 17 passes through the contact portion (supply position SP) with the supply roller 16 N times (N is an arbitrary integer equal to or greater than 1) times, the supply roller 16 contacts the developing roller 17. The contact state is maintained (NO in step ST3). N is a value determined in advance by setting. In the meantime, the developer is supplied onto the N first scheduled portions (S1, S2), and the development for the N image area (P1, P2) is performed.

  As described above with reference to FIG. 6 and FIG. 7, the supply roller 16 is brought into contact with the first counter-planned portion S1, the supply roller 16 is separated from the second counter-planned portion T1, and the first counter-planned portion S2 is formed. The value of N is set to 1 for the operation of bringing the supply roller 16 into contact with and separating the supply roller 16 from the second facing portion T2. The value of N can be set to an arbitrary value as necessary. If the value of N is set to 1, the supply roller 16 is separated from the second counter-scheduled part every time the second counter-scheduled part passes, but if the value of N is set to 2, the second counter Each time the scheduled portion passes twice, the supply roller 16 is separated from the second facing scheduled portion at a rate of once. That is, the supply roller 16 only needs to be separated from the second counter-scheduled part at a predetermined timing when the second counter-scheduled part passes so that the deterioration of the developer due to the accumulation of frictional heat can be suppressed.

  After the first counter-scheduled portion (S1, S2) on the developing roller 17 has passed the supply position SP N times (YES in step ST3), the control unit 30 drives the drive mechanism 20 to determine a predetermined value based on the value of N. In this timing, the supply roller 16 is separated from the developing roller 17 (step ST4). The separation state is continued until the second scheduled portion (for example, T2) on the developing roller 17 starts to be located at the supply position SP until the second opposite planned portion almost passes through the supply position SP. During this time, the developer is not supplied from the supply roller 16 to the second opposed portion on the developing roller 17, and no frictional heat is generated between the supply roller 16 and the developing roller 17.

  After the second counter-scheduled part has almost passed the supply position SP, when there is no other first counter-scheduled part downstream of the second counter-scheduled part (YES in step ST5), continuous printing operation Ends (step ST8). On the other hand, after the second counter-scheduled part has almost passed through the supply position SP, when the first counter-scheduled part exists downstream of the second counter-scheduled part (NO in step ST5), the control unit 30 detects the rotational position of the developing roller 17 (step ST6).

  The control unit 30 detects the rotational position of the developing roller 17 until another first opposed portion on the developing roller 17 starts to reach the supply position SP (NO in step ST7). When the controller 30 determines that the first opposed portion on the developing roller 17 has started to reach the supply position SP (determines that the timing at which the contact operation of the supply roller 16 with the developing roller 17 is to be started has been reached). (When YES in step ST7), the drive mechanism 20 is driven and controlled, and the drive mechanism 20 brings the supply roller 16 into contact with the developing roller 17 (step ST1). The control unit 30 repeats the above steps until it can be determined in step ST5 that printing has ended based on the signal input to the control unit 30.

  With reference to FIG. 10 (A) and FIG. 10 (B), the above operation | movement is demonstrated in detail using a timing chart. FIG. 10A is a diagram showing a change with time of the developer amount on the developing roller 17 located immediately downstream of the nip portion formed between the supply roller 16 and the developing roller 17. FIG. 10B is a diagram showing a change with time of the distance (distance between the axes) between the rotation axis of the supply roller 16 and the rotation axis of the developing roller 17. Here, as an example, it is assumed that the value of N is 1.

  During the period from time T0 to time Ta, the first opposed planned portion S1 of the developing roller 17 is located at the supply position SP. The supply roller 16 and the developing roller 17 are in contact with each other (contact state). The developer is supplied from the supply roller 16 to the developing roller 17, and an appropriate amount of developer is carried on the surface 17 </ b> S of the developing roller 17. This developer is used for developing an electrostatic latent image.

  At time Ta, the most downstream portion of the first opposed planned portion S1 of the developing roller 17 is located at the supply position SP. During the period from time Ta to time Tb, the second facing portion T1 of the developing roller 17 is located at the supply position SP. Here, when the supply roller 16 is separated from the developing roller 17, the supply amount of the developer from the supply roller 16 to the developing roller 17 is likely to vary with time, and the supply amount is different for each separation operation. There is.

  The developer supplied onto the developing roller 17 in a state where the supply amount is varied starts from a portion corresponding to the supply position SP on the developing roller 17 and starts upstream of that portion while the developing roller 17 rotates. It may spread to the first counter-scheduled portion S1. Therefore, the separation operation is not simultaneous with the most downstream portion of the first counter-planned portion S1 (the boundary portion between the first counter-planned portion S1 and the second counter-planned portion T1) passing the supply position SP ( In other words, not at the time Ta, but at the time Tb, it is delayed by the time t1 after the most downstream portion of the first opposed portion S1 passes the supply position SP. During this time, the most downstream part of the first counter-scheduled part S1 further moves, for example, about 5 mm from the supply position SP.

  The separation operation started at time Tb is completed at time Tc. Between the time Tb and the time Tc, the distance between the shafts gradually increases, and the amount of developer on the developing roller 17 immediately after the nip portion (supply position SP) (downstream side) gradually decreases.

  During the period from time Tc to time Td, the developer is not supplied from the supply roller 16 to the development roller 17. At time Td, the drive mechanism 20 is driven, and the supply roller 16 starts to approach the developing roller 17. Between the time Td and the time Te, the distance between the shafts gradually decreases, and the amount of the developer on the developing roller 17 immediately after the nip portion (supply position SP) (downstream side) gradually increases.

  Here, at the time Tf, the most downstream portion of the second facing portion T1 of the developing roller 17 is located at the supply position SP. Immediately after the contact operation (pressure contact operation) of the supply roller 16 with respect to the developing roller 17 is completed, the amount of developer supplied from the supply roller 16 to the development roller 17 tends to vary over time, and the contact operation every time. Different supply amounts are likely to occur for each (pressure contact operation).

  Therefore, the abutting operation is completed at the same time as the most downstream part of the second counter-scheduled part T1 (the boundary part between the second counter-scheduled part T1 and the first counter-scheduled part S2) passes through the supply position SP. (In other words, the contact operation is not completed at time Tf), but the time point t2 earlier than the most downstream portion of the second counter-scheduled portion T1 passes the supply position SP (time Te) The contact operation may be started from time Td so that the pressure contact operation is completed. In this case, the contact operation is completed when the most upstream portion of the first opposite-facing portion S2 is located about 5 mm before the supply position SP (at time Te).

  Between the time Tf and the subsequent time Ta, the first opposed scheduled portion S2 of the developing roller 17 is located at the supply position SP. The supply roller 16 and the developing roller 17 are in contact with each other (contact state). The developer is supplied from the supply roller 16 to the developing roller 17, and an appropriate amount of developer is carried on the surface 17 </ b> S of the developing roller 17. The operation as described above is repeated for the second opposing scheduled portion T2 and the first opposing scheduled portion S3.

  As described above, in the wet image forming apparatus 100 according to the present embodiment, when the surface 16S of the supply roller 16 is opposed to the first opposed portions S1 and S2, the surface 16S of the supply roller 16 is in the supply position. The developer is supplied from the supply roller 16 to the first opposed portions S1 and S2 by being arranged on the SP and in contact with or in pressure contact with the developing roller 17.

  On the other hand, when the surface 16S of the supply roller 16 is opposed to the second opposed portions T1 and T2 (in other words, when the second opposed portions T1 and T2 are located at the supply position SP), the supply roller The surface 16S of 16 is separated from the surface 17S (supply position SP) of the developing roller 17. As described above, the inter-image areas Q1 and Q2 on the photoconductor 5 that are scheduled to face the second opposed portions T1 and T2 are not used for image formation. Even if the developer is not supplied to the second oppositely scheduled portions T1 and T2, the wet image forming apparatus 100 uses the developer supplied to the first oppositely scheduled portions S1 and S2 and is necessary for the printing paper. Images can be formed continuously.

  Therefore, the wet image forming apparatus 100 can effectively suppress the generation of frictional heat between the developing roller 17 and the supply roller 16. Since the generation of frictional heat is suppressed, the wet image forming apparatus 100 can also suppress the deterioration of the developer and can stably obtain a good image even during continuous image formation.

[Embodiment 2]
In the first embodiment described above, the developing roller 17 and the supply roller 17 so that the surface 17S of the developing roller 17 and the surface 16S of the supply roller 16 move in the opposite directions at the contact portion (supply position SP) between them. The roller 16 rotates. In the first embodiment described above, frictional heat generated by counter rotation is effectively reduced.

  As in the liquid developing device 6A shown in FIG. 11, the developing roller 17 so that the surface 17S of the developing roller 17 and the surface 16S of the supply roller 16 move in the same direction at the contact portion (supply position SP) between them. 17 and the supply roller 16 may be rotating. If the moving speed of the surface 17S (first surface) of the developing roller 17 is different from the moving speed of the surface 16S (second surface) of the supply roller 16, frictional heat is generated between the supply roller 16 and the developing roller 17. . Even when a configuration such as the liquid developing device 6A is employed, the same effect as in the first embodiment can be obtained by the drive mechanism 20 operating in the same manner as in the first embodiment. it can.

[Embodiment 3]
FIG. 12 is a first view showing the liquid developing device 6B in the present embodiment (the supply roller 16 is in contact with the developing roller 17). FIG. 13 is a second view showing the liquid developing device 6B in the present embodiment (the supply roller 16 is separated from the developing roller 17).

  As shown in FIGS. 12 and 13, the drive mechanism 20 </ b> B of the liquid developing device 6 </ b> B includes a cam 26. The cam 26 has a convex portion 26T. The cam 26 is connected to a motor (not shown) for driving the developing roller 17 through a gear, and is configured to rotate once every time one image is formed. The cam 26 has such a size and shape that the convex portion 26 </ b> T contacts the arm 21 at a timing at which the supply roller 16 should be separated from the developing roller 17.

  By the rotating operation of the cam 26, a state where the supply roller 16 is brought into contact with the developing roller 17 as shown in FIG. 12, and a state where the supply roller 16 is separated from the developing roller 17 as shown in FIG. It can be switched at an appropriate timing. In this structure, the size of the printing paper on which an image is formed by the wet image forming apparatus (in other words, the image area) has the same width in the circumferential direction, and the area between the images in the circumferential direction is the same. It can be used particularly effectively when the widths are all the same.

  A configuration in which the convex portion 26T of the cam 26 and the rotating shaft of the supply roller 16 are brought into contact without providing the arm 21 is also effective. Even when the arm 21 is not provided, even if the supply roller 16 is separated from the developing roller 17 in order to stably form a uniform developer layer on the developing roller 17, the pumping roller 15 and the supply roller 16 are preferably rotated so that the developer amount on the supply roller 16 is always stable.

  Even when a configuration such as the liquid developing device 6B is employed in the wet image forming apparatus, the drive mechanism 20B operates in the same manner as in the first embodiment, so that the same as in the first embodiment described above. An effect can be obtained.

[Embodiment 4]
FIG. 14 is a diagram showing the liquid developing device 6C in the present embodiment (the supply roller 16 is in contact with the developing roller 17). FIG. 15 is also a diagram showing the liquid developing device 6C in the present embodiment (the supply roller 16 is separated from the developing roller 17). Like the liquid developing device 6C, the pumping roller (the pumping roller 15 in the above-described embodiment) may not be provided. In this case, the regulating member 25 is provided so as to contact the supply roller 16. The regulating member 25 adjusts the developer amount on the supply roller 16 to an appropriate amount.

  Even when a configuration such as the liquid developing device 6C is employed in the wet image forming apparatus, the drive mechanism 20 operates in the same manner as in the first embodiment, so that the same as in the first embodiment described above. An effect can be obtained.

  As mentioned above, although each embodiment based on this invention was described, each embodiment disclosed this time is an illustration and restrictive at no points. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Paper feeder, 2 Paper conveyance path, 3 Transfer roller, 4 Intermediate transfer body, 5 Photoreceptor (image carrier), 5S surface, 6, 6A, 6B, 6C Liquid developing device, 7, 11, 19 Cleaning device, 8 Latent Image Eraser, 9, 18 Charging Device, 10 Exposure Device, 12 Fixing Device, 13 Paper Discharge Device, 14 Developer Tank, 14W Developer, 15 Assembly Roller (Other Developer Supply Body), 16 Supply Roller ( Developer supply body), 16S surface (second surface), 17 development roller (developer carrier), 17S surface (first surface), 20, 20B drive mechanism, 21 arm, 22, 24 gear, 23 drive motor, 25 restricting member, 26 cam, 26T convex part, 30 control part, 31 detecting part, 40 spring, 100 wet image forming apparatus, DP developing position, a, b, c, d, e, DR Arrow, P1, P2 image part area, Q1, Q2 inter-image area, S1, S2, S3 first opposing planned part, SP supply position, ST1, ST2, ST3, ST4, ST5, ST6, ST7, ST8 step, T0, Ta, Tb, Tc, Td, Te, Tf, t1, t2 Time, T1, T2 Second opposed portions.

Claims (4)

A liquid developing device that develops an electrostatic latent image contained in a plurality of image area regions continuously formed on an image carrier while leaving a space between images using a developer containing a carrier liquid and toner. There,
A developer carrier having a first surface to which the developer is supplied, and transporting the developer to a development position facing the image carrier by movement of the first surface;
A developer supply body that has a second surface with a moving speed different from the moving speed of the first surface and supplies the developer to the first surface in a state where the second surface is in contact with the first surface. When,
A drive mechanism for separating and abutting the first surface and the second surface;
The drive mechanism is
When the second surface of the developer supply body is opposed to a first opposed portion of the first surface of the developer carrying member that faces the image area, the first surface and the first surface Two surfaces are brought into contact with each other,
The first surface at a predetermined timing when the second surface of the developer supply body is opposed to a second opposed portion of the first surface of the developer carrier that faces the inter-image region. And separating the second surfaces from each other,
Liquid developing device. The first surface of the developer carrier and the second surface of the developer supply body move in opposite directions;
The liquid developing device according to claim 1. Further provided with another developer supply body that contacts the developer supply body and supplies the developer to the developer supply body.
The liquid developing device according to claim 1. An image carrier;
An image forming mechanism for forming an electrostatic latent image on the image carrier;
The liquid developing device according to claim 1, wherein the electrostatic latent image formed on the image carrier by the image forming mechanism is developed.
Wet image forming apparatus.

Images