JP2008197130A - Wet developing apparatus and wet image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet developing apparatus with amount of liquid developer corresponding to a type of transfer paper uniformly formed on a developer carrier, and to provide a wet image forming apparatus capable of forming a high quality image by using the wet developing apparatus. <P>SOLUTION: A rotational speed control means controlling the rotational speed of a supplying roller is provided with: a first pulley which is provided at a driving shaft of the developer carrier, on the outer periphery of which a V-shaped groove is formed, and which is divided into two so that at least one of them is movable in an axial direction; a second pulley which is provided at a driving shaft of a supplying roller, on the outer periphery of which a V-shaped groove is formed, and which is divided into two so that at least one of them is movable in an axial direction; a V-belt wound around the V-shaped grooves in the first and the second pulleys; and a control mechanism varying spacing of inclined surfaces in the first and the second pulleys. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wet developing apparatus and a wet image forming apparatus having a wet developing apparatus.

  Conventionally, an electrostatic latent image on the surface of an image carrier is developed with a liquid developer in which toner particles are dispersed in an insulating carrier liquid, and the toner image formed by the development is transferred to a transfer material to obtain a final image. An image forming apparatus is known. In addition, the toner image formed by the development with the liquid developer is primarily transferred to an intermediate transfer member, a plurality of toner images are superimposed on the surface of the intermediate transfer member, and then the superimposed toner images are collectively transferred to a transfer material. An image forming apparatus that obtains a final image is also known.

  A wet image forming apparatus using such a wet developing apparatus has an advantage that cannot be realized by a dry image forming apparatus, and its value is being reviewed in recent years. The main advantages of wet-type image forming devices are that submicron-size extremely fine toner can be used, so that high-quality images can be obtained and the quality of printing can be obtained, and the toner can be fixed to a transfer material at a relatively low temperature. It is possible to realize energy saving. Particularly, in recent years, with the increase in the speed of image forming apparatuses, a liquid developer in which toner particles are dispersed at a high concentration in a highly viscous carrier liquid tends to be used.

  Incidentally, an electrostatic transfer method using an electrostatic force is generally used for transferring a toner image onto a transfer material in a wet image forming apparatus. The toner particles are charged in advance, and the toner particles move to the transfer material due to the electrostatic force generated by applying a voltage of the opposite polarity to the toner particles to the transfer roller provided on the back side of the transfer material. Complete.

  However, when a transfer material having a large surface roughness (also referred to as transfer paper) such as non-coated paper is used, a larger amount of toner is required to obtain the same image density as that of the coated paper. This is because non-coated paper has a larger surface area than coated paper, and therefore requires a larger amount of toner to cover the surface.

  When a liquid developer having a high concentration of 10% to 50% and a high viscosity liquid developer is used, the photosensitive member and the developer carrying member move at a constant speed, and the image on the photosensitive member is transferred. Generally, a method of moving almost 100% of the toner on the developer carrying member corresponding to the region is taken. For this reason, when the required toner amount changes depending on the type of transfer paper, the toner amount on the developer carrying member is constant, causing a problem that the density of the transferred image changes.

  In view of such problems, the amount of toner on the photosensitive member is controlled by controlling the amount of developer on the developer carrying member according to the properties of the transfer paper to be transferred. Has proposed a method for optimizing the image density by increasing the amount of developer on the photoreceptor.

  For example, Patent Document 1 proposes a method for controlling the rotation speed of a supply roller that applies toner to a developer carrier and a method for controlling the pressing force of the supply roller to the developer carrier.

Patent Document 2 proposes a method of controlling the developer amount of the developer carrying member by the rotation speed of the supply roller and controlling the charge amount of the toner according to the developer amount.
JP-A-11-212368 JP 2005-234430 A

  However, in general, as a driving method of the supply roller, a method of directly connecting a motor to the supply roller or driving from a developer carrier having a driving source through a gear train has been adopted. When a motor that directly drives the supply roller is attached, there is a problem that the developing device becomes large and heavy and difficult to handle. Further, when driving from a developer carrier through a gear train, the gear pitch becomes uneven in the supply, and the developer layer is uneven in thickness on the developer carrier, causing image noise. .

  Therefore, the technical problem to be solved by the present invention is to provide a wet developing apparatus and a wet image forming apparatus that suppress the occurrence of image noise without increasing the size of the apparatus even when the rotational speed of the supply roller is controlled. Is to provide.

  This invention can achieve the said subject with the following structures.

1.
In a wet developing apparatus for developing an electrostatic latent image using a liquid developer in which toner particles are dispersed in a carrier liquid,
A developer carrier for carrying and transporting a liquid developer on the surface;
A supply roller for supplying a liquid developer to the developer carrier;
A rotation speed control means for controlling the rotation speed of the supply roller,
The rotational speed control means includes
A first pulley provided on the drive shaft of the developer carrying member, forming a V-shaped groove on the outer periphery thereof, and at least one of which is divided into two so as to be movable in the axial direction;
A second pulley provided on the drive shaft of the supply roller, forming a V-shaped groove on the outer periphery thereof, and at least one of which is divided into two so as to be movable in the axial direction;
A V belt wound around a V-shaped groove of the first pulley and the second pulley;
And a control mechanism that changes a slope interval of the V-shaped grooves of the first pulley and the second pulley.

2.
2. The wet developing apparatus according to 1, wherein the control mechanism includes a cam mechanism coupled to the first pulley and the second pulley.

3.
3. The wet developing apparatus according to 2, wherein the control mechanism includes a clutch that selectively transmits a driving force of the developer carrying member to the cam mechanism.

4).
2 or 3, wherein the cam mechanism is a cylindrical cam in which a groove is formed in a cylindrical surface so that the slope interval of the V-shaped groove can be continuously increased or decreased by rotation in the same direction. The wet developing apparatus as described.

5.
An image carrier that carries an electrostatic latent image on its surface;
The wet developing apparatus according to any one of 1 to 4,
Transfer means for transferring a toner image obtained by developing an electrostatic latent image to the transfer material by the wet developing device;
A discriminating means for discriminating the type of the transfer material,
The wet image forming apparatus, wherein the rotation speed control means controls the rotation speed of the supply roller in accordance with the type of the transfer material.

  According to the present invention, the rotation speed control means for controlling the rotation speed of the supply roller is provided. The rotation speed control means is provided on the drive shaft of the developer carrier, and has a V-shaped groove formed on the outer periphery thereof. , At least one of which is provided on the drive pulley of the supply pulley divided into two so as to be movable in the axial direction, and a V-shaped groove is formed on the outer periphery thereof, and at least one of them is moved in the axial direction A second pulley that is divided into two, a V belt wound around a V-shaped groove of the first pulley and the second pulley, and a slope interval of the V-shaped groove of the first pulley and the second pulley The wet developing apparatus and the wet image forming apparatus that suppress the generation of image noise without increasing the size of the apparatus even when the rotation speed of the supply roller is controlled. Can be provided.

  Embodiments of the present invention will now be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a wet image forming apparatus according to an embodiment of the present invention. Around the photoconductor 5 as an image carrier, a charging device 12, an exposure device 13, a wet developing device 100, an intermediate transfer body 7, a photoconductor cleaning device 8, and a static elimination lamp 11 are arranged in the order indicated by the arrows. Has been placed. A transfer roller 9 and an intermediate transfer body cleaning device 10 are arranged around the intermediate transfer body 7.

  The toner image developed by the wet developing device 100 and formed on the photoconductor 5 is transferred to the intermediate transfer body 7 and then transferred to the transfer paper 15 as a transfer material by the transfer roller 9. Thereafter, the toner image on the transfer paper 15 is fixed by the fixing device 90 to form an image.

  The wet developing device 100 includes a developing tank 1 that stores a liquid developer 2 in which toner particles are dispersed in an insulating carrier liquid, a supply roller 14 that pumps the liquid developer 2 from the developing tank 1, and a liquid that is supplied from the supply roller 14. The developing roller 4 is a developer carrying member that receives the developer and develops the photosensitive member 5.

  Since the developing roller 4 is developed in contact with the photoreceptor 5, the surface is made of an elastic body. Further, since the supply roller 14 contacts the developing roller 4 and supplies the liquid developer, the surface may be an elastic body or a metal roller.

  Further, this wet developing apparatus is provided with a rotational speed control means for controlling the rotational speed of the supply roller 14 so that the amount of liquid developer applied to the surface of the developing roller 4 can be adjusted according to the type of transfer paper. The rotation speed control means and control method will be described later in detail.

  Next, the operation of the image forming apparatus in FIG. 1 will be described.

  The photoreceptor 1 rotates in the direction of arrow c. First, the charging device 12 uniformly charges the surface of the photoconductor 5 to a predetermined potential. Thereafter, image exposure is performed by the exposure device 13 to form a latent image on the surface of the photoreceptor 5. The latent image on the photosensitive member 5 is developed by the developing roller 4 of the developing device 100. The developing roller 4 connected to the drive source rotates in the direction a in the figure, and the peripheral speed of the developing roller 4 and the peripheral speed of the photosensitive member 5 are the same speed. At this time, an amount of liquid developer 2 corresponding to the type of transfer paper 15 to be used is supplied from the supply roller 14 on the surface of the developing roller 4 and is uniformly formed as a coating film. The liquid developer 2 used in the developing device 100 is obtained by dispersing toner particles in an insulating carrier liquid, and may further contain a function-imparting agent such as a charge control agent or a dispersant. After development, the liquid developer on the developing roller 4 is cleaned by the developing roller cleaning blade 6.

  The concentration and viscosity of the liquid developer 2 are not particularly limited, but a solid component such as toner particles is dispersed at a rate of 10 to 50% by mass, and the viscosity at 25 ° C. is in the range of 1 mPa · s to 10000 mPa · s. This is particularly suitable when a liquid developer having a high concentration and a high viscosity is used. The toner particles are previously charged positively.

  An operation for forming a coating film of the liquid developer on the surface of the developing roller 4 will be described.

  First, the liquid developer 2 stored in the developing tank 1 is pumped up by the supply roller 14. The liquid developer on the surface of the supply roller 14 drawn up is regulated to a certain film thickness by the regulating blade 3 to form a thin layer. The thin layer is transported to a facing portion (supply portion) between the supply roller 14 and the developing roller 4 by the rotation of the supply roller 14, and a certain amount is supplied to the developing roller 4. The moving direction of the surface of the supply roller 14 in the supply unit and the moving direction of the surface of the developing roller 4 are opposite to each other, and a uniform thin layer can be formed on the surface of the developing roller 4. The developing roller 4 develops the latent image on the surface of the photoreceptor 5.

  When the photoconductor 5 further rotates, the toner image on the photoconductor 5 developed by the liquid developer 2 moves to a primary transfer region where the photoconductor 5 and the intermediate transfer body 7 are in contact with each other. A negative voltage is applied to the intermediate transfer member 7 by a power source (not shown), and the toner moves by the electric field generated by the applied voltage, whereby the toner image on the surface of the photosensitive member 5 is transferred to the surface of the intermediate transfer member 7. Primary transcription.

  After the primary transfer, the liquid developer remaining on the photoconductor 5 is removed by the cleaning device 8, and then the surface of the photoconductor 5 is neutralized by the static elimination lamp 11, and the surface of the photoconductor 5 is uniformly charged again by the charging device 12. Repeat the image forming operation. The intermediate transfer member 7 may be in the form of a drum but may be in the form of a belt.

  The toner image formed on the surface of the intermediate transfer member 7 moves to a secondary transfer region where the intermediate transfer member 7 and the transfer paper 15 contact each other as the intermediate transfer member 7 rotates in the direction of the arrow.

  In the secondary transfer region, a linear pressure is applied between the intermediate transfer body 7 and the transfer paper 15 by the transfer roller 9 on the back side of the transfer paper 15, while a negative voltage is applied to the transfer roller 9 by a power source (not shown). Applied. Due to this applied voltage, the surface of the transfer paper 15 facing the intermediate transfer member 7 also has a negative potential, and the toner image is transferred to the transfer paper 15 by the potential difference between the surface potential of the transfer paper 15 and the surface potential of the intermediate transfer member 7. To be attracted to the surface. In this state, when the transfer paper 15 is conveyed in the direction of the arrow and leaves the secondary transfer area, the secondary transfer of the toner image onto the transfer paper 15 is completed.

  After the secondary transfer, the liquid developer remaining on the intermediate transfer member 7 is removed by the intermediate transfer member cleaning device 10.

  The transfer paper 15 onto which the toner image has been transferred is subjected to fixing processing by the fixing device 90, and image output is completed.

  By the way, in this embodiment, the application amount of the liquid developer on the developing roller 4 can be controlled by the type of the transfer paper 15.

  As the control means, the type of the transfer paper 15 is selected by the selection means, and the rotational speed of the supply roller 14 for supplying the liquid developer to the developing roller 4 is controlled by the rotational speed control means based on the selection result. ing.

  The configuration and control method of the rotation speed control means 20 for controlling the rotation speed of the supply roller 14 will be described in detail with reference to FIG.

  The rotational speed control means 20 is provided on the drive shaft of the developing roller 4 connected to the drive source 40, has a V-shaped groove on the outer periphery thereof, and at least one of the two is divided into two so as to be movable in the axial direction. The pulley A (21a, 21b), which is the first pulley, is provided on the shaft of the supply roller 14, and a V-shaped groove is formed on the outer periphery thereof, and at least one of them is divided into two so as to be movable in the axial direction. The pulley B (22a, 22b) which is the second pulley, the V belt 30 wound around the V-shaped grooves of the pulleys A and B, and the slope intervals of the V-shaped grooves of the first pulley and the second pulley. And a control mechanism to be changed.

  The first pulley, the second pulley and the control mechanism of this rotational speed control means will be described in detail. The control mechanism includes a cylindrical cam 50, an electromagnetic clutch gear 52, and a gear 57.

  When the pulley A rotates due to the rotation of the drive source 40, the pulley B rotates and the supply roller 14 rotates. The pulleys 21a, 21b, 22a, and 22b constituting the pulleys A and B form the slopes of the V-shaped grooves of the pulleys A and B, respectively, and the distances between the slopes of the slopes 21a and 21b and 22a and 22b (slope spacing) Is narrower toward the center of the pulley and wider toward the outer periphery. That is, the V-belt 30 is driven on the center side of the pulley when the slope interval of the pulley is widened, and is driven on the outer peripheral side of the pulley when the slope interval of the pulley is narrowed.

  In FIG. 2, the developing roller shaft 41 and the supply roller shaft 42, which are spline shafts, include pulleys 21a, 21b, 22a, and 22b that are integrally formed with bearings 23 to 26, so that each shaft The top is movable.

  Moreover, the outer peripheral part of the bearings 23-26 is engaging with the groove | channel of the cylindrical cam 50 which cut the groove | channel on the cylindrical surface. FIG. 3 schematically shows an engaged state between the outer peripheral portions of the bearings 23 to 26 and the groove portion 51 of the cylindrical cam 50. 4a and 4b schematically show the displacement d in the axial direction of the bearings 23 to 26 when the cylindrical cam 50 makes one rotation. When the cylindrical cam 50 is rotated, the outer peripheral portions of the bearings 23 to 26 engaged with the groove portions 51 of the cylindrical cam 50 are moved. As shown in FIGS. A groove is formed in the cylindrical surface so as to return to the position. By using this mechanism, the slope interval between the V-shaped grooves of pulleys 21a and 21b, which are integrally formed with the bearing, is narrowed, the slope interval between the V-shaped grooves of pulleys 22a and 22b is increased, and On the contrary, it is possible to perform control to increase the slope interval of the V-shaped grooves of the pulleys 21a and 21b and narrow the slope interval of the V-shaped grooves of the pulleys B 22a and 22b.

  By using such a control mechanism, by controlling the rotation angle in one direction of the cylindrical cam 50 as shown in FIG. 2, the interval between the V-shaped grooves of the pulley A is widened while the V-shaped groove of the pulley B is expanded. You can narrow the interval and vice versa.

  That is, the slope interval of the V-shaped groove formed by the pulleys 21a and 21b and the slope interval of the V-shaped groove formed by the pulleys 22a and 22b are changed in conjunction with each other, and the development roller 4 and the supply roller 14 are changed. The rotational speed of the supply roller 14 can be controlled without changing the distance between the axes. FIG. 5 shows a cross-sectional view when the rotation speed of the supply roller 14 is maximized with respect to the developing roller 4. By narrowing the slope interval of the V-shaped groove formed by the pulleys 21a and 21b and widening the slope distance of the V-shaped groove formed by the pulleys 22a and 22b, the position where the V belt 30 is applied is shown in the figure. Thus, the pulley A is on the outer peripheral side, and the pulley B is on the inner peripheral side. FIG. 6 shows a cross section taken along the line AA in FIG. In this way, the winding position of the V-belt 30 is a position away from the shaft center in the pulley A because the slope interval of the V-shaped grooves is narrow, and in the pulley B, the slope interval of the V-shaped grooves is widened. The position is close to the axis center. As a result, the rotation speed of the supply roller 14 with respect to the developing roller 4 can be increased, and the rotation speed ratio of the supply roller 14 with respect to the developing roller 4 becomes R1 / R2. FIG. 7 is a cross-sectional view when the rotation speed of the supply roller 14 is minimized with respect to the developing roller 4. The position where the V belt 30 is applied is increased by increasing the slope interval of the V-shaped groove formed by the pulleys 21a and 21b and narrowing the slope distance of the V-shaped groove formed by the pulleys 22a and 22b. Thus, the pulley A is on the inner peripheral side, and the pulley B is on the outer peripheral side. FIG. 8 shows a BB cross section in FIG. 7 at this time. In such a state, the rotation speed of the supply roller 14 relative to the developing roller 4 can be reduced.

  Returning to FIG. 2, the driving of the cylindrical cam 50 will be described. The cylindrical cam 50 is connected to a gear 57, and the gear 57 is driven by an electromagnetic clutch gear 52. The electric clutch gear 52 is integrated with the developing roller shaft 41 by operating the electric clutch, and rotates the gear 57 by the rotation of the developing roller 41. At this time, the rotation angle of the cylindrical cam 50 is determined by controlling the operation time of the electric clutch. The amount of displacement d of the bearings 23 to 26 is determined by the rotation angle as shown in FIGS. 4a and 4b. With this displacement d, the rotational speed of the supply roller 14 can be controlled as schematically shown in FIG. That is, the rotation speed of the supply roller 14 can be controlled by the operation time of the electromagnetic clutch.

  FIG. 10 shows an example of an electromagnetic clutch gear 52 having an electromagnetic clutch. By passing an electric current through the electromagnetic clutch, the clutch portion 521 is operated to rotate integrally with the developing roller 4. The clutch mechanism is not limited to the electromagnetic clutch, and other methods may be used. However, since the electromagnetic clutch is simple and can be manufactured in a space-saving manner, and the time control can be accurately performed, the rotation speed of the supply roller 14 can be increased. Can be changed smoothly. Further, although a gear train for transmitting driving force from the electromagnetic clutch gear 52 to the gear 57 is used, the electromagnetic clutch gear 52 is changed from a spur gear to an electromagnetic clutch gear 53 of a bevel gear as shown in FIG. The worm gear 55 may be rotated via the worm gear 55 and the cylindrical rack 56 may be rotated by the worm gear 55 to rotate the cylindrical cam 50 connected to the cylindrical rack 56.

  In addition, the pulleys A and B 21a and 21b, and 22a and 22b can be stably maintained by urging them in directions away from each other. FIG. 12 shows a state in which the pulley A is biased by the compression spring 27. Also in the pulley B, the stable space | interval can be maintained by urging | biasing 22a, 22b mutually outward using the compression spring 28. FIG. By doing so, the rotation speed of the supply roller 14 can be driven more stably.

  Further, if the rotation speed control means of the supply roller 14 can be connected to the developing roller 4 and the supply roller 14 by the coupling members 61 and 62 shown in FIG. 2, it can be easily separated from the developing device main body. This makes it easier to maintain and manage the rotation speed control means.

  In such a configuration, a method for controlling the rotation speed of the supply roller 14 so that the amount of the liquid developer varies depending on the type of the transfer paper 15 on the surface of the developing roller 4 will be described.

  First, the reason why the amount of toner to be transferred onto the transfer paper 15 varies depending on the type of the transfer paper 15 will be described. In order to keep the image density on the transfer paper 15 constant, a large amount of toner is required to cover the uneven surface of the transfer paper 15 having a large surface unevenness, such as uncoated paper. Further, in the case of coated paper with small irregularities, the surface can be covered with a smaller amount compared to non-coated paper. For this purpose, it is necessary to change the amount of toner on the photoreceptor 5 in accordance with the transfer paper 15.

  In general, in the wet developing apparatus 100 in which a thin layer of high-concentration liquid developer is formed, the toner corresponding to the image portion on the developing roller 4 is transferred almost 100%. This is because, by controlling the surface potential of the photoconductor 5, it is difficult to control the amount of the toner thin layer having a high density and high viscosity on the developing roller 4 in the middle, and the vertical stripe shape is formed on the image. This is because it becomes easier to generate noise. Therefore, in order to control the toner amount of the image portion on the photoconductor 5, it is necessary to control the toner amount on the developing roller 4. The toner amount on the developing roller 4 can be controlled by changing the rotation speed of the supply roller 14 that supplies the liquid developer to the developing roller 4.

  The operation of controlling the amount of liquid developer applied on the developing roller 4 according to the type of transfer paper 15 will be described with reference to FIG.

  First, the operator selects the type of transfer paper 15 at the operation unit. Based on the selected type of transfer paper 15, the control board retrieves the operation time of the electromagnetic clutch of the electromagnetic clutch gear 52 from the storage device, and transmits a signal corresponding to the operation time to the controller and driver of the electromagnetic clutch. The rotational speed of the supply roller 14 is controlled.

  Instead of the operation of selecting the type of transfer paper 15 by the operator as described above, a detection device that automatically detects the type of transfer paper on the paper feed tray is used, and the transfer paper 15 is based on the detection result. It is also possible to determine and control the type. As the detection device, for example, a sensor for measuring the surface roughness of the transfer paper can be provided.

  The surface hardness of the developing roller 4 according to the present invention is preferably 20 to 60 degrees (JIS A). If the surface hardness exceeds 60 degrees, the contact width at the contact developing portion with the photoreceptor 5 is reduced, and stable development cannot be performed. Further, if the surface hardness is less than 20 degrees, there is a problem that the cleaning blade that cleans the developer remaining on the surface of the developing roller 4 after developing the latent image on the photoreceptor 5 causes scratches.

  The surface hardness of the supply roller 14 according to the present invention is preferably 50 degrees (JIS A) or more. If the surface hardness is less than 50 degrees, the amount of liquid developer cannot be stably regulated. This restricts the regulating blade 3 by pressing it against the surface of the supply roller 14, so that the contact pressure of the regulating blade 3 changes due to the eccentricity of the supply roller 14. Due to the pressure change of the regulating blade 3, the amount of elastic deformation at the contact portion of the surface of the supply roller 14 with the regulating blade 3 changes greatly. For this reason, the regulated amount of liquid developer on the supply roller 14 changes and the amount of liquid developer on the developing roller 4 changes, so that a density change easily occurs. Further, the surface of the supply roller 14 is scraped by the regulating blade 3 to be cheap, and the surface is shaved as the number of prints increases, the vertical stripe-shaped regulation unevenness and the liquid developer amount after regulation are reduced, and the density on the image is reduced. Decrease and vertical stripe density unevenness occur and become a problem.

  As a material of the rubber roller on the surface of the developing roller 4 and the supply roller 14, NBR, polyurethane, or those obtained by coating urethane resin or fluororesin on them can be used.

  Next, the liquid developer configuration will be described.

  The liquid developer mainly contains an insulating liquid as a carrier liquid, a toner for developing an electrostatic latent image, and a dispersant for dispersing the toner.

  The carrier liquid can be used without particular limitation as long as it is generally used for an electrophotographic developer, but a non-volatile liquid is particularly preferable. Examples of the non-volatile liquid include mineral oils such as silicon oil, mineral oil, and paraffin oil.

  Any toner can be used without particular limitation as long as it is generally used for an electrophotographic developer. As the binder resin for toner, for example, thermoplastic resins such as polystyrene resin, styrene-acrylic resin, acrylic resin, polyester resin, epoxy resin, polyamide resin, polyimide resin, and polyurethane resin can be used. A plurality of these resins may be mixed and used. Also, commercially available pigments and dyes used for coloring the toner can be used. For example, as the pigment, carbon black, bengara, titanium oxide, silica, phthalocyanine blue, phthalocyanine green, sky blue, benzidine yellow, lake red D, and the like can be used. Solvent red 27, acid blue 9, or the like can be used as the dye.

  The developer can be prepared based on a commonly used technique. For example, the binder resin and the pigment are melt-kneaded using a pressure kneader, a roll mill or the like at a predetermined blending ratio and uniformly dispersed, and the obtained dispersion is finely pulverized by, for example, a jet mill. By classifying the obtained fine powder with, for example, an air classifier, a colored toner having a desired particle diameter can be obtained.

  Subsequently, the obtained toner is mixed with an insulating liquid as a carrier liquid at a predetermined blending ratio.

  This mixture can be uniformly dispersed by a dispersing means such as a ball mill to obtain a developer.

  The viscosity of the liquid developer used in the wet developing apparatus according to the present invention is preferably 1 mPa · s to 10000 mPa · s, and the toner concentration is preferably 10 to 50% by mass. In addition, the viscosity of the developer was measured with a viscosity measuring device ares (product number: FR-100) manufactured by TA Instruments.

  In this embodiment, the rotation speed of the supply roller is controlled according to the type of transfer paper, but it may be controlled according to the environmental conditions in which the image forming apparatus is installed, for example, temperature and humidity. Furthermore, the rotation speed of the supply roller may be changed to set a desired density.

  Next, examples of the present invention will be described.

  The wet image forming apparatus shown in FIG. 1 was used. The photoreceptor 5 is an aluminum drum having a diameter of 210 mm formed with an organic photoreceptor film (film thickness: 35 μm), and the rotational peripheral speed was set to 350 mm / sec. As the charging device 12, a scorotron charger was used so that the surface potential of the photosensitive member 5 was -450V. The exposure device 13 was set so that the surface potential of the photoreceptor 5 was −100 V when the image portion was exposed with a semiconductor laser.

  As the liquid developer, black toner in a color copier C350 manufactured by Konica Minolta Business Technologies, Ltd. was pulverized into a carrier liquid (Moresca P120 manufactured by Matsumura Oil Co., Ltd.), and an average particle diameter of 3 μm was added. A dispersant (Solsperse 13940, manufactured by Avicia) was added at 10% by mass based on the toner amount. The charge amount of the toner of the obtained liquid developer was −100 μC / g.

  The conditions of the developing roller 4 of the wet developing apparatus 100 are as follows.

Diameter: 40mm
Material: NBR + carbon black Volume resistivity: 1.0 × 10 ⁶ Ω · cm
Rubber hardness: 40 °
Rotational peripheral speed: 420 mm / sec
Bias voltage: -300V
The conditions of the supply roller 14 are as follows.

Diameter: 40mm
Material: NBR + carbon black Volume resistivity: 1.0 × 10 ⁶ Ω · cm
Rubber hardness: 60 °
Peripheral speed ratio (θ): 0.6 to 2.2
Peripheral speed ratio control method: Motor rotation speed control directly connected to the supply roller shaft Push amount (d): 0.1 mm, 0.3 mm
Push-in amount control method: Position control by eccentric cam (configuration of FIGS. 5 and 6)
Bias voltage: -300V
As the regulating blade 3 of the supply roller 14, a SUS 0.3 mm blade was used.

  As the photoconductor cleaning blade, a silicon rubber blade having a diameter of 3 mm is used, and is in contact with the tangent line of the photoconductor 201 at an angle of 20 degrees during the cleaning operation. The pressure contact force is 0.341 N / cm.

  The intermediate transfer member 7 has a diameter of 100 mm and a urethane coating of 0.03 mm on the surface of a 5 mm urethane rubber substrate.

  As the intermediate transfer member cleaning blade 10, urethane rubber having a diameter of 3 mm is used, and is in contact with the counter at an angle of 20 degrees from the tangent to the intermediate transfer member 7 during the cleaning operation. The pressure contact force is 30 N / m.

Under this condition, the rotation speed control of the supply roller 14 according to the type of transfer paper was performed using the control means shown in FIG. By controlling the operation time of the electromagnetic clutch, the rotation speed of the supply roller 14 is changed. When coated paper A (surface roughness Ra: 0.5 μm) is applied, the liquid developer is 5 mg / ml on the surface of the developing roller 4. It was controlled so as to be m ² and adjusted so as to obtain an optimum image density on the transfer paper. At this time, the speed ratio of the supply roller 14 to the developing roller 4 was 0.8. For the transfer paper of non-coated paper B (surface roughness Ra: 3 μm), the amount of liquid developer on the surface of the developing roller 4 is controlled to 10 mg / m ² so that the optimum image density is obtained on the transfer paper. It was adjusted. At this time, the speed ratio of the supply roller 14 to the developing roller 4 was 1.5.

  Under these conditions, 5 sheets of A4 size chart with a black-and-white ratio (B / W) of 20% were continuously printed on coated paper A, then 5 sheets were continuously printed on uncoated paper B, and this operation was repeated 20 times for a total of 2000. Image evaluation was performed on the coated paper A and the non-coated paper B after the sheets were printed. Both coated paper A and non-coated paper B had no image unevenness and were good images.

1 is a diagram illustrating a schematic configuration of a wet image forming apparatus according to an embodiment of the present invention. It is a figure which shows schematic structure of the rotational speed control means of the supply roller of the developing device which is one Embodiment of this invention. It is a figure which shows typically the engagement state of the bearing and cylindrical cam of the rotation speed control means which concern on this invention. It is a figure which shows typically the displacement amount d of the axial direction of a bearing when the cylindrical cam which concerns on this invention makes one rotation. It is a schematic diagram of a cross section of a pulley and a V belt when the rotation speed of a supply roller is maximized with respect to the developing roller according to the present invention. It is a schematic diagram of the side surface of the pulley and the V belt when the rotation speed of the supply roller is maximized with respect to the developing roller according to the present invention. It is a schematic diagram of the side surface of the pulley and the V belt when the rotation speed of the supply roller is minimized with respect to the developing roller according to the present invention. It is a schematic diagram of the side surface of the pulley and the V-belt when the rotation speed of the supply roller is minimized with respect to the developing roller according to the present invention. It is a figure which shows typically the operating time of the clutch which concerns on this invention, and the rotation speed of a supply roller. It is a figure which shows an example of the electromagnetic clutch gear 52 which has an electromagnetic clutch. It is a figure which shows the example of the gear train using a spur gear and a worm gear. It is explanatory drawing which incorporated the compression spring in the pulley. FIG. 6 is a block diagram for controlling the number of rotations of a supply roller according to the type of transfer paper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing tank 2 Liquid developer 3 Regulating blade 4 Developing roller 5 Photoconductor 6 Developing roller cleaning blade 7 Intermediate transfer body 8 Photoconductor cleaning device 9 Transfer roller 10 Intermediate transfer body cleaning device 100 Wet developing device 11 Static elimination lamp 12 Charging device 13 Exposure device 14 Supply roller 15 Transfer paper 90 Fixing device 20 Rotational speed control means 40 Drive source 21a, 21b Pulley A
22a, 22b Pulley B
30 V belt 41 Developing roller shaft 42 Supply roller shaft 23, 24, 25, 26 Bearing 50 Cylindrical cam 51 Groove portion 52, 53 Electromagnetic clutch gear 521 Clutch portion 57 Gear 54 Bevel gear 55 Warm gear 56 Cylindrical rack 28 Compression springs 61, 62 Coupling member

Claims (5)

In a wet developing apparatus for developing an electrostatic latent image using a liquid developer in which toner particles are dispersed in a carrier liquid,
A developer carrier for carrying and transporting a liquid developer on the surface;
A supply roller for supplying a liquid developer to the developer carrier;
A rotation speed control means for controlling the rotation speed of the supply roller,
The rotational speed control means includes
A first pulley provided on the drive shaft of the developer carrying member, forming a V-shaped groove on the outer periphery thereof, and at least one of which is divided into two so as to be movable in the axial direction;
A second pulley provided on the drive shaft of the supply roller, forming a V-shaped groove on the outer periphery thereof, and at least one of which is divided into two so as to be movable in the axial direction;
A V belt wound around a V-shaped groove of the first pulley and the second pulley;
And a control mechanism that changes a slope interval of the V-shaped grooves of the first pulley and the second pulley. The wet developing apparatus according to claim 1, wherein the control mechanism includes a cam mechanism coupled to the first pulley and the second pulley. The wet developing apparatus according to claim 2, wherein the control mechanism includes a clutch that selectively transmits a driving force of the developer carrying member to the cam mechanism. 3. The cam mechanism according to claim 2, wherein the cam mechanism is a cylindrical cam in which a groove is formed in a cylindrical surface so that the slope interval of the V-shaped groove can be continuously widened or narrowed by rotation in the same direction. 4. The wet developing apparatus according to 3. An image carrier that carries an electrostatic latent image on its surface;
A wet developing apparatus according to any one of claims 1 to 4,
Transfer means for transferring a toner image obtained by developing an electrostatic latent image to the transfer material by the wet developing device;
A discriminating means for discriminating the type of the transfer material,
The wet image forming apparatus, wherein the rotation speed control means controls the rotation speed of the supply roller in accordance with the type of the transfer material.

Images