JP2008209661A - Developing device and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the quality of a developing device and electrophotographic apparatus by uniformizing the film thickness of a layer of liquid toner moved from a developing roller to a photoreceptor drum. <P>SOLUTION: The developing device includes: a tank 21 for storing liquid toner of a prescribed concentration; a supply roller 22, the part of which is soaked in the liquid toner in the tank 21 and which is capable of scooping the liquid toner; a smoothing roller 23; a developing roller 24 to/from which the liquid toner is transferred; a power source device 25 which applies a bias voltage to the developing roller 24; and a charging device 51 which adheres the liquid toner supplied to the circumferential face of the developing roller 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device that forms a toner image by supplying charged liquid toner to a photosensitive drum, and an electrophotographic device that transfers and fixes a toner image formed by the developing device onto a sheet.

  A conventional electrophotographic apparatus includes a photosensitive drum, a charging device that charges the photosensitive drum, an exposure device that exposes an image on the photosensitive drum, and a toner charged on a portion of the photosensitive drum where an electrostatic latent image is formed. A developing device that supplies an electrostatic latent image to the image, a transfer drum that transfers the toner image formed on the photosensitive drum to the paper, and a fixing device that fixes the toner image transferred to the paper. ing.

  Accordingly, the surface of the photosensitive drum is charged with a polarity corresponding to the toner characteristics by the charging device, and the image is exposed on the photosensitive drum charged by the exposure device. On the other hand, the liquid toner stored in the tank is transferred to the developing roller by the supply roller, and a thin liquid toner layer is formed on the developing roller. Then, the liquid toner layer on the developing roller is brought close to the electrostatic latent image formed on the surface of the photosensitive drum, the toner layer charged by electrostatic force is moved onto the photosensitive drum, and a toner image is formed on the photosensitive drum. Then, the toner image formed on the photosensitive drum is transferred to a sheet, and the toner image transferred onto the sheet by a fixing device is thermally melted and fixed.

  In the developing device of the conventional electrophotographic apparatus configured as described above, the liquid toner contains toner particles having charging characteristics. The liquid toner is pumped up by the supply roller and transferred to the developing roller. A thin liquid toner layer is formed on the roller, and the liquid toner layer on the developing roller is moved onto the photosensitive drum by electrostatic force to form a toner image.

  Note that the above-described conventional electrophotographic apparatus is described in Patent Document 1 below.

Japanese Patent No. 3650431

  In the above-described conventional electrophotographic apparatus, the surface of the photosensitive drum is charged in advance by a charging device, an image is exposed on the photosensitive drum charged by the exposure device, and an electrostatic latent image is formed. By bringing the supplied liquid toner layer close to the electrostatic latent image on the photosensitive drum, the toner layer charged by the electrostatic force is moved onto the photosensitive drum to form a toner image. However, the liquid toner layer formed on the developing roller is in a state where toner particles having charging characteristics are floating in the solvent, and when the liquid toner layer is moved on the photosensitive drum by electrostatic force, the toner particles adhere to each other. If the force is insufficient, the film thickness of the toner image tends to be non-uniform, and the quality may be degraded.

  The present invention solves the above-described problems, and provides a developing apparatus and an electrophotographic apparatus that improve the quality by uniformizing the thickness of the liquid toner layer that is moved from the developing roller to the photosensitive drum. Objective.

  In order to achieve the above object, a developing device according to the first aspect of the present invention includes a tank storing liquid toner of a predetermined concentration, and a supply capable of pumping up the liquid toner by being partially immersed in the liquid toner in the tank. A roller, a developing roller that delivers liquid toner from the supply roller, a voltage applying device that applies a bias voltage to the developing roller, and a charging device that charges the liquid toner supplied to the outer peripheral surface of the developing roller. It is characterized by comprising.

  According to a second aspect of the present invention, the charging device includes a discharge electrode and a housing that surrounds the discharge electrode and has an opening on one side thereof, and the opening of the housing is formed on the outer peripheral surface of the developing roller. It is characterized by being arranged facing each other.

  According to a third aspect of the present invention, a leveling roller is disposed between the supply roller and the development roller, and a roller moving direction at a contact portion between the supply roller and the leveling roller is set to the same direction. In addition, the moving direction of the roller at the contact portion between the leveling roller and the developing roller is set in a reverse direction.

  According to a fourth aspect of the present invention, there is provided a developing device including a cleaning member for removing the liquid toner remaining on the developing roller, and a voltage applying device for applying a bias voltage to the cleaning member.

  In a developing device according to a fifth aspect of the present invention, the cleaning member is a cleaning roller or a cleaning blade in contact with the developing roller.

  The developing device according to claim 6 is characterized in that a collecting electrode is provided to face the outer peripheral surface of the cleaning member.

  In a developing device according to a seventh aspect of the present invention, a part of the cleaning member is immersed in liquid toner.

  In the developing device according to an eighth aspect of the present invention, a loosening roller that contacts the developing roller is provided upstream of the cleaning member in the developing roller in the rotational direction.

  In a developing device according to a ninth aspect of the present invention, the loosening roller is supported by a swinging device so as to be swingable in the axial direction.

  According to a tenth aspect of the present invention, there is provided an electrophotographic apparatus comprising: a tank in which liquid toner having a predetermined concentration is stored; a supply roller that is partially immersed in the liquid toner in the tank; A developing roller to which liquid toner is delivered, a voltage applying device that applies a bias voltage to the developing roller, a toner charging device that charges the liquid toner supplied to the outer peripheral surface of the developing roller, and a contact with the developing roller A photosensitive drum that delivers liquid toner, a photosensitive drum charging device that charges the outer peripheral surface of the photosensitive drum, an exposure device that exposes an image on the charged photosensitive drum, and a toner image that is in contact with the photosensitive drum. A transfer drum that is primarily transferred, a secondary transfer roll that secondarily transfers a toner image onto the paper by sandwiching the paper between the transfer drum, and a secondary transfer onto the paper. It is characterized in that comprises a fixing device which fixes the toner image.

  According to the developing device of the first aspect of the present invention, a tank that stores liquid toner of a predetermined concentration, a supply roller that is partly immersed in the liquid toner in the tank and pumps up the liquid toner, and a liquid from the supply roller A developing roller to which the toner is delivered, a voltage applying device that applies a bias voltage to the developing roller, and a charging device that charges the liquid toner supplied to the outer peripheral surface of the developing roller are provided.

  Therefore, the supply roller pumps up the liquid toner in the tank and delivers it to the developing roller. At this time, the bias voltage is applied to the developing roller by the voltage applying device, and the liquid toner supplied to the outer peripheral surface of the developing roller by the charging device. Therefore, the adhesion between the toner particles in the liquid toner on the developing roller is increased, the thickness of the liquid toner moving from the developing roller to the photosensitive drum can be made uniform, and the quality can be improved. .

  According to the developing device of the second aspect of the present invention, the charging device is provided with the discharge electrode and a housing that surrounds the discharge electrode and has an opening on one side so that the opening of the housing faces the outer peripheral surface of the developing roller. Therefore, the corona discharge generated from the discharge electrode can be irradiated only toward the surface of the developing roller by the housing, and the discharge efficiency can be improved.

  According to the developing device of the third aspect of the invention, the leveling roller is disposed between the supply roller and the development roller, and the roller moving direction at the contact portion between the supply roller and the leveling roller is set in the same direction. Since the roller moving direction at the contact portion between the leveling roller and the developing roller is set in the reverse direction, the supply roller pumps up the liquid toner in the tank and supplies it to the leveling roller, and the leveling roller develops this liquid toner. At this time, since the roller moving direction is the same in the contact portion between the supply roller and the leveling roller, when the supply roller supplies the leveling roller, the liquid toner layer has a film thickness unevenness. However, since the roller moving direction is reverse at the contact portion between the leveling roller and the developing roller, the film thickness unevenness of the liquid toner layer is eliminated, and the liquid toner supplied to the developing roller is removed. film It can be equalized.

  According to the developing device of the fourth aspect of the present invention, the cleaning member for removing the liquid toner remaining on the developing roller is provided, and the voltage applying device for applying the bias voltage is connected to the cleaning member. The liquid toner to be removed can be easily removed and recovered, and the toner recovery efficiency can be improved.

  According to the developing device of the fifth aspect of the invention, since the cleaning member is a cleaning roller or a cleaning blade that contacts the developing roller, the liquid toner remaining on the developing roller can be easily removed and collected easily with a simple configuration. can do.

  According to the developing device of the sixth aspect of the invention, since the collecting electrode is provided so as to face the outer peripheral surface of the cleaning member, the liquid toner remaining on the developing roller is easily removed by the cleaning member and cleaned by the collecting electrode. The toner on the roller can be collected, and the toner collection efficiency can be improved.

  According to the developing device of the seventh aspect of the invention, since a part of the cleaning member is immersed in the liquid toner, the toner on the cleaning roller can be properly recovered and the toner recovery efficiency can be improved. In addition, since the residual toner after cleaning passes through an electric field, the toner is agglomerated and has a high viscosity and poor fluidity. However, when a part of the cleaning member is immersed in the toner, Bad recovered toner can be brought into contact with solvent-rich toner to improve fluidity and be recovered directly in the tank.

  According to the developing device of the eighth aspect of the present invention, since the loosening roller that contacts the developing roller is provided upstream of the cleaning member in the developing roller in the rotation direction, the liquid toner remaining on the developing roller is removed beforehand by the loosening roller. By peeling off from the surface, the cleaning member can easily remove and collect the liquid toner remaining on the developing roller, and the toner recovery efficiency can be improved.

  According to the developing device of the ninth aspect, since the loosening roller is supported by the swinging device so as to be swingable in the axial direction, the liquid toner remaining on the developing roller is removed by swinging the loosening roller in the axial direction. Can be solved properly.

  According to the electrophotographic apparatus of the tenth aspect of the present invention, there is provided a tank in which liquid toner of a predetermined concentration is stored, a supply roller that is partially immersed in the liquid toner in the tank and pumped up, and the supply roller. A developing roller to which liquid toner is delivered, a voltage applying device for applying a bias voltage to the developing roller, a toner charging device for charging the liquid toner supplied to the outer peripheral surface of the developing roller, and a liquid toner in contact with the developing roller Drum, a photosensitive drum charging device for charging the outer peripheral surface of the photosensitive drum, an exposure device for exposing an image on the charged photosensitive drum, and a transfer drum on which the toner image is primarily transferred in contact with the photosensitive drum And a secondary transfer roll that secondarily transfers the toner image onto the paper by sandwiching the paper between the transfer drum and the toner image that has been secondarily transferred onto the paper. And a fixing device is provided that.

  Therefore, the photosensitive drum charging device charges the outer peripheral surface of the photosensitive drum, and the exposure device exposes the image to the charged photosensitive drum, while the supply roller pumps up the liquid toner in the tank and transfers it to the developing roller, and develops it by the voltage applying device. In addition to applying a bias voltage to the roller, the toner charging device charges the liquid toner on the developing roller, transfers the charged liquid toner from the developing roller to the photosensitive drum, and primarily transfers the toner image on the photosensitive drum to the transfer drum. The toner image is secondarily transferred to the paper by sandwiching the paper between the transfer drum and the secondary transfer roll, and the fixing device fixes the toner image secondarily transferred to the paper. Since the liquid toner is charged by the voltage application device and the toner charging device, the adhesion between the toner particles in the liquid toner on the developing roller is high. Becomes, the thickness of the liquid toner to move from the developing roller to the photosensitive drum can be made uniform, thereby improving the quality.

  Exemplary embodiments of a developing device and an electrophotographic apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example.

  1 is a schematic configuration diagram of an electrophotographic apparatus to which a developing device according to Embodiment 1 of the present invention is applied. FIG. 2 is a front view of an anilox roller in the developing device of Embodiment 1. FIG. FIG. 4A to FIG. 4C are schematic views illustrating the movement state of the toner particles by the developing device according to the first embodiment.

  As shown in FIG. 1, an electrophotographic apparatus to which the developing device of Example 1 is applied includes a photosensitive drum 11, a charging device (photosensitive drum charging device) 12 that charges the photosensitive drum 11, and an image on the photosensitive drum 11. Formed on the photosensitive drum 11, an exposure device 13 that exposes the toner, a developing device 14 that visualizes the electrostatic latent image by supplying charged toner to a portion of the photosensitive drum 11 where the electrostatic latent image is formed. A transfer device 15 for transferring the toner image onto a predetermined paper, and a fixing device 16 for fixing the toner image transferred onto the paper. In the description of the present embodiment, one photosensitive drum 11 is provided for the transfer device 15, and the charging device 12, the exposure device 13, and the developing device 14 are provided for the photosensitive drum 11. In this case, a plurality of, for example, four photosensitive drums are provided for the transfer device 15, and a charging device, an exposure device, and a developing device are provided for the photosensitive drum.

  The photosensitive drum 11 has a configuration in which an organic or amorphous silicon photosensitive layer is provided on a conductive substrate such as aluminum, and is supported on a frame (not shown) so as to be rotatable counterclockwise in FIG. By exposing the photosensitive layer to light, an electrostatic latent image can be formed on the surface. A charging device 12 and an exposure device 13 are arranged around the photosensitive drum 11 along the rotation direction. The charging device 12 can uniformly apply an electrostatic potential to the surface of the photosensitive drum 11 by corona discharge or the like. The exposure device 13 can form an electrostatic latent image by irradiating the photosensitive layer of the photosensitive drum 11 with a light image. Further, around the photosensitive drum 11, a cleaning device 17 is disposed upstream of the charging device 12 and the exposure device 13 in the rotational direction. The cleaning device 17 includes a cleaning roller or a cleaning blade, and is photosensitive. The liquid toner remaining on the surface of the drum 11 can be removed and collected in the tank 21.

  The developing device 14 includes a tank 21 in which liquid toner of a predetermined concentration is stored, a supply roller (anilox roller) 22 that is partly immersed in the liquid toner in the tank 21 and can pump up the liquid toner, and the supply roller. The leveling roller 23 is in contact with the leveling roller 22 and the developing roller 24 is in contact with the leveling roller 23 and receives liquid toner. The developing roller 24 is in contact with the photosensitive drum 11.

  The supply roller 22 is composed of a metal anilox roller having a large number of recesses, and the recesses are helical grooves 22a inclined at a predetermined angle θ with respect to the axial direction of the supply roller 22, as shown in detail in FIG. The helical groove 22 a is formed in parallel over the entire circumference of the supply roller 22. The leveling roller 23 is made of NBR (nitrile / butylene / rubber), and the surface is formed of a conductive member that does not swell in the liquid toner. The developing roller 24 is also made of NBR (nitrile / butylene / rubber), and its surface is formed of a conductive member that does not swell in the liquid toner. The leveling roller 23 and the developing roller 24 are not limited to NBR, and may be a foamed material such as polystyrene, polyethylene, polyurethane, and polyvinyl chloride, or a low-hardness rubber member such as silicon rubber or urethane rubber.

  The supply roller 22, the leveling roller 23, and the developing roller 24 are arranged in a substantially linear shape in a contact state, and are rotatably supported by a frame (not shown). In this case, in FIG. 1, the supply roller 22 rotates counterclockwise, the leveling roller 23 rotates clockwise, the developing roller 24 rotates clockwise, and the photosensitive drum 11 rotates counterclockwise. Rotate in the direction. Therefore, by rotating the supply roller 22, the liquid toner stored in the tank 21 can be pumped up, and this liquid toner can be supplied to the leveling roller 23 whose contact portion moves in the same direction. By rotating the leveling roller 23, the liquid toner can be transferred to the developing roller 24 whose contact portion moves in the opposite direction, and is further supplied to the photosensitive drum 11 whose contact portion moves in the same direction. can do.

  A power supply device (voltage application device) 25 is connected to the leveling roller 23 and the developing roller 24. Accordingly, by applying a bias voltage to the leveling roller 23 and the developing roller 24 by the power supply device 25, the supply amount of the liquid toner can be adjusted by the electric field generated in the leveling roller 23 and the developing roller 24. In addition, a toner stirring device 26 that stirs the liquid toner in the tank 21 is provided. Therefore, by driving the toner stirring device 26, the concentration of the liquid toner stored in the tank can be maintained uniformly.

  As described above, in the developing device 14, as shown in FIG. 3, the roller moving directions 22a and 23a at the contact portion A between the supply roller 22 and the leveling roller 23 are set in the same direction, and the leveling roller 23 is set. The roller moving directions 23b and 24a at the contact portion B between the developing roller 24 and the developing roller 24 are set in the reverse direction. As described above, the supply roller 22 is a metal anilox roller, and the helical groove 22a is formed as a recess. Further, since the leveling roller 23 and the developing roller 24 are formed by NBR, at least the outer peripheral surface has an elastic layer, and the liquid toner passes through the contact portion between the leveling roller 23 and the developing roller 24. A possible minute gap is provided, and the solvent of the liquid toner has a lubricating performance.

  Accordingly, the liquid toner stored in the tank 21 can be supplied from the supply roller 22 to the developing roller 24 via the leveling roller 23. At this time, the contact portion between the supply roller 22 and the leveling roller 23 In A, since the roller moving directions 23b and 24a are the same direction, film thickness unevenness occurs in the liquid toner layer supplied from the supply roller 22 to the leveling roller 23, but the leveling roller 23 and the developing roller 24 Since the roller moving directions 23b and 24a are opposite in the contact portion B, the film thickness unevenness of the liquid toner layer is eliminated and the film thickness of the liquid toner supplied to the developing roller 24 is made uniform.

  That is, the liquid toner that has entered the helical groove 22a of the supply roller 22 moves to the leveling roller 23 when it contacts the leveling roller 23, but this liquid toner layer has an anilox pattern (helical shape). When the liquid toner on the surface of the leveling roller 23 comes into contact with the developing roller 24, the liquid toner layer of this anilox pattern is crushed by the surface of the developing roller 24, thereby uniformizing the film thickness. In this case, since the anilox pattern has a helical shape, the liquid toner is crushed along the longitudinal direction of the helical shape, and moves to the developing roller 24 while the film thickness remains uniform. Then, the liquid toner solvent enters a minute gap provided between the leveling roller 23 and the developing roller 24, so that the contact portion between the leveling roller 23 and the developing roller 24 is lubricated.

  As shown in FIGS. 1 and 3, the developing device 14 of the present embodiment is connected to a power supply device 25 with respect to the developing roller 24, and uses liquid toner supplied to the outer peripheral surface of the developing roller 24. A charging device (toner charging device) 51 for charging is provided. The charging device 51 includes a tungsten wire 52 serving as a discharge electrode, a box-shaped housing 53 that surrounds the tungsten wire 52 and has an opening 53 a on one side, and a power supply device 54. The opening 53 a is disposed so as to face the outer peripheral surface of the developing roller 24.

  Therefore, as shown in FIG. 3, the liquid toner supplied from the supply roller 22 to the developing roller 24 through the leveling roller 23 is applied through the developing roller 24 by the bias voltage of the power supply device 25, and is shown in FIG. As shown, the liquid toner layer adheres to the surface of the developing roller 24, and the toner particles are suspended in the solvent. Here, when the tungsten wire 52 is energized by the power supply device 54 in the charging device 51, a corona discharge occurs and is collected by the housing 53 and irradiated to the liquid toner on the developing roller, as shown in FIG. In the liquid toner layer, the toner particles move to the surface side thereof, are aligned, and are in close contact with each other. Then, when the developing roller 24 rotates and the liquid toner layer in which the toner particles are aligned approaches the electrostatic latent image formed on the surface of the photosensitive drum 11, it is charged by electrostatic force as shown in FIG. The toner particles in the liquid toner layer move onto the photosensitive drum 11 while being in close contact with the aligned state.

  Further, as shown in FIG. 1, the developing device 14 measures the concentration of the liquid toner pumped up by the supply roller 22 and the toner concentration adjusting device 27 that adjusts the toner concentration by supplying the toner and the solvent to the tank 21. The toner density measuring device 28 and a control device 29 for controlling the toner density adjusting device 27 based on the measurement result of the toner density measuring device 28 are provided.

  That is, in the toner concentration adjusting device 27, the first and second replenishing tanks 32 and 33 are connected to the tank 21 via the first and second supply lines 30 and 31. The first replenishment tank 32 stores concentrated toner, the second replenishment tank 33 stores solvent, and the first replenishment tank is opened and closed by opening and closing the on-off valves 34 and 35 provided in the supply lines 30 and 31. The concentrated toner stored in 32 can be supplied to the tank 21 through the first supply line 30, and the solvent stored in the second replenishing tank 33 can be supplied to the tank 21 through the second supply line 31. In this case, the liquid toner is obtained by dispersing a resin containing a pigment in a solvent, and the toner particles are resin particles having charging characteristics.

  The toner concentration measuring device 28 is an optical sensor disposed opposite to the outer peripheral surface of the supply roller 22 and includes a light emitting portion 28a and a light receiving portion 28b, and measures the concentration of the liquid toner based on the light transmittance. be able to. In this case, the supply roller 22 is an anilox roller, and is rotated while immersed in the liquid toner stored in the tank 21, so that the liquid toner is pumped up by entering into the numerous helical grooves 22 a. The toner concentration measuring device 28 can appropriately measure the concentration of the liquid toner entering the helical groove 22a by irradiating and receiving a predetermined area on the outer peripheral surface of the supply roller 22.

  The control device 29 is connected to the toner concentration adjusting device 27 and the toner concentration measuring device 28. The toner concentration measured by the toner concentration measuring device 28 is inputted, and the measured toner concentration is set to a predetermined toner set in advance. The toner density adjusting device 27 is controlled so as to obtain the density. That is, when the toner concentration measured by the toner concentration measuring device 28 is lower than the predetermined toner concentration, the control device 29 opens the on-off valve 34 and supplies the concentrated toner stored in the first replenishing tank 32 to the first supply. When the toner concentration supplied from the line 30 to the tank 21 and measured by the toner concentration measuring device 28 is higher than the predetermined toner concentration, the on-off valve 35 is opened, and the solvent stored in the second replenishing tank 33 is stored in the second replenishing tank 33. Supply from the supply line 31 to the tank 21.

  The transfer device 15 includes a transfer drum 41 and a secondary transfer roller 42. The transfer drum 41 is disposed so as to be in contact with the photosensitive drum 11, and the toner image on the photosensitive drum 11 can be primarily transferred onto the transfer drum 41 by electrostatic force. The transfer drum 41 is formed of, for example, NBR (nitrile / butylene / rubber), and rotates in a clockwise direction in FIG. 1 on a frame (not shown). The secondary transfer roller 42 rotates in a counterclockwise direction in FIG. 1 on a frame (not shown), and can sandwich and press a sheet with the transfer drum 41. A cleaning device 43 is disposed around the transfer drum 41 on the downstream side in the rotational direction from the position of contact with the secondary transfer roller 42. The cleaning device 43 is provided by a cleaning roller, a cleaning blade, or the like. The liquid toner remaining on the surface of the transfer drum 41 can be removed and collected in the tank 21.

  The fixing device 16 includes a fixing roller 44 and a pressure roller 45. The fixing roller 44 is formed of a silicon sponge roller, is overheated to a high temperature by a built-in heater, and rotates clockwise in FIG. 1 to a frame (not shown). The pressure roller 45 is made of NBR (nitrile / butylene / rubber) and rotates in a counterclockwise direction in FIG. 1 on a frame (not shown). Accordingly, the sheet S sandwiched between the fixing roller 44 and the pressure roller 45 is heated by the fixing roller 44, and the toner particles in the transferred toner image are melted to be fixed on the sheet S.

  In the electrophotographic apparatus of this embodiment, the photosensitive drum 11, the supply roller 22, the leveling roller 23, the developing roller 24, the transfer drum 41, the secondary transfer roller 42, the fixing roller 44, and the pressure roller 45 include: The driving force of one drive motor (not shown) is transmitted through a plurality of gears, chains, and the like, so that synchronous rotation is possible. The driving method is not limited to this method, and the photosensitive drum 11, the supply roller 22, the leveling roller 23, the developing roller 24, the transfer drum 41, the secondary transfer roller 42, the fixing roller 44, and the pressure roller 45 are individually driven. You may make it rotate with a motor.

  Here, the operation of the above-described electrophotographic apparatus of this embodiment will be described.

  In the electrophotographic apparatus of this embodiment, first, the charging device 12 performs corona discharge on the photosensitive drum 11 to charge the surface of the photosensitive drum 11 with a polarity corresponding to the toner characteristics. Next, the image is exposed on the photosensitive drum 11 charged by the exposure device 13. In this case, the image is exposed by a scanner to form an electrostatic latent image on the surface of the photosensitive drum 11. That is, the portion exposed to the light from the scanner becomes conductive, so that the charge disappears, and the portion not exposed to the light remains as an electrostatic latent image that is an image of the charge.

  On the other hand, the electrostatic latent image on the photosensitive drum 11 is visualized by the developing device 14. That is, when the supply roller 22 is rotated, the liquid toner stored in the tank 21 is pumped up by the supply roller 22, and the liquid toner of the supply roller 22 is supplied to the leveling roller 23 and supplied to the leveling roller 23. The liquid toner is transferred to the developing roller 24, and a thin liquid toner layer is formed on the developing roller 24. At this time, by adjusting the bias voltage applied to the leveling roller 23 and the developing roller 24 by the power supply device 25, the film thickness of the liquid toner layer is adjusted by the electric field generated in the leveling roller 23 and the developing roller 24. Further, the charging device 51 performs corona discharge on the liquid toner on the developing roller 24 to bring the toner particles floating in the solvent into an aligned state in close contact with each other.

  At this time, the toner density measuring device 28 irradiates the surface of the supply roller 22 with light from the light emitting unit 28a, and receives the reflected light with the light receiving unit 28b. The concentration of the liquid toner adhering to the surface is measured. Then, the control device 29 controls the toner concentration adjusting device 27 based on the toner concentration measured by the toner concentration measuring device 28. That is, when the toner concentration measured by the toner concentration measuring device 28 is lower than the predetermined toner concentration, the control device 29 opens the on-off valve 34 and supplies the concentrated toner in the first replenishing tank 32 from the first supply line 30 to the tank. By supplying to 21, the concentration of the liquid toner in the tank 21 is increased. On the other hand, when the toner concentration measured by the toner concentration measuring device 28 is higher than the predetermined toner concentration, the control device 29 opens the on-off valve 35 to remove the solvent in the second replenishing tank 33 from the second supply line 31. By supplying to 21, the concentration of the liquid toner in the tank 21 is reduced.

  Then, by bringing the liquid toner layer on the developing roller 24 close to the electrostatic latent image formed on the surface of the photosensitive drum 11, the liquid toner charged by electrostatic force is moved onto the photosensitive drum 11, A toner image is formed on the surface. At this time, since the liquid toner layer on the developing roller 24 is in an aligned state in which the toner particles are in close contact with each other, the liquid toner layer is charged when approaching the electrostatic latent image formed on the surface of the photosensitive drum 11. The liquid toner layer is moved onto the photosensitive drum 11 while the toner particles are in close contact with each other, and a toner image having a uniform thickness is formed on the photosensitive drum 11.

  Subsequently, the toner image formed on the photosensitive drum 11 is transferred onto the paper S by the transfer device 15. That is, the toner image formed on the photosensitive drum 11 is primarily transferred onto the transfer drum 41 by electrostatic force generated between the photosensitive drum 11 and the toner image primarily transferred onto the transfer drum 41. Due to the pressing force applied to the transfer drum 41 by the secondary transfer roller 42, secondary transfer is performed on the sheet S fed between the transfer drum 41 and the secondary transfer roller 42. On the other hand, the liquid toner remaining on the photosensitive drum 11 and the transfer drum 41 is removed by the cleaning devices 17 and 43 and collected in the tank 21.

  Finally, the toner image secondarily transferred onto the sheet is fixed by the fixing device 16. That is, as the sheet S passes between the high-temperature fixing roller 44 and the pressure roller 45, the sheet S is heated by the high-temperature fixing roller 44, and the toner particles in the transferred toner image are melted. Fix to paper S.

  As described above, in the developing device 14 applied to the electrophotographic apparatus according to the first exemplary embodiment, the tank 21 that stores liquid toner of a predetermined concentration and the liquid toner in the tank 21 are partially immersed in the liquid toner. Is supplied to the outer peripheral surface of the developing roller 24, the leveling roller 23, the developing roller 24 to which the liquid toner is transferred, the power supply device 25 for applying a bias voltage to the developing roller 24, and the developing roller 24. A charging device 51 for charging the liquid toner is provided.

  Accordingly, the supply roller 22 pumps up the liquid toner in the tank 21 and delivers it to the developing roller 24 via the leveling roller 23. At this time, the power supply device 25 applies a bias voltage to the developing roller 24 and also the charging device 51. As a result, the liquid toner supplied to the outer peripheral surface of the developing roller 24 is charged, that is, the solid content of the liquid toner is compressed, so that the adhesion between the toner particles in the liquid toner on the developing roller 24 is increased. The film thickness of the liquid toner moving to the photosensitive drum 11 can be made uniform, the edges of the toner image can be formed sharply, and the resolution of electrophotography can be increased to improve the quality.

  As the charging device 51, a tungsten wire 52, a housing 53 that surrounds the tungsten wire 52 and has an opening 53 a on one side, and a power supply device 54 are provided, and the opening 53 a of the housing 53 is formed on the outer peripheral surface of the developing roller 24. It arrange | positions so that it may oppose. Therefore, corona discharge generated from the tungsten wire 52 can be irradiated toward the surface of the developing roller 24 by the housing 53, and charging efficiency can be improved.

  Further, in the developing device 14 of this embodiment, the supply roller 22 is a metal anilox roller having a large number of recesses on the surface, and a liquid toner layer having a predetermined thickness can be easily formed on the surface of the developing roller 24. Can improve quality. Further, the concave portion of the supply roller 22 is formed as a helical groove 22a inclined by a predetermined angle θ with respect to the axial direction, so that a liquid toner layer having a predetermined film thickness can be uniformly formed on the surface of the developing roller 24, thereby improving quality. can do.

  Further, in the developing device 14 of the present embodiment, the leveling roller 23 and the developing roller 24 are formed of NBR, thereby providing an elastic layer on the outer peripheral surface and providing a lubricating performance to the liquid toner solvent. Therefore, even if the roller moving direction is the reverse direction at the contact portion B between the leveling roller 23 and the developing roller 23, liquid toner having a lubricating performance enters between the elastic layers. Damage to the surface of the developing roller 24 can be suppressed. In this case, a gap through which the liquid toner can pass is provided at the contact portion B between the leveling roller 23 and the developing roller 24, and the liquid toner having lubricating performance passes through the gap. Damage to the surface of the developing roller 24 can be appropriately suppressed.

  In addition, the electrophotographic apparatus of the present embodiment includes a photosensitive drum 11, a charging device 12, an exposure device 13, a developing device 14, a transfer device 15, and a fixing device 16, and the developing device 14 is provided. The tank 21, the supply roller 22, the leveling roller 23, the developing roller 24, the power supply device 25, and the charging device 51.

  Therefore, the film thickness of the liquid toner supplied from the developing device 14 to the photosensitive drum 11 can be made uniform, and the print quality can be improved.

  FIG. 5 is a schematic configuration diagram illustrating a developing device according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the second embodiment, the developing device 61 includes a tank 21 in which liquid toner of a predetermined concentration is stored, a supply roller 22 that is partly immersed in the liquid toner in the tank 21 and can pump up the liquid toner, and this supply The leveling roller 23 is in contact with the roller 22, and the developing roller 24 is in contact with the leveling roller 23 and receives liquid toner. The developing roller 24 is in contact with the photosensitive drum 11.

  In the developing device 61 of this embodiment, a cleaning roller 62 is provided in contact with the developing roller 24. A part of the cleaning roller 62 is immersed in a reserve tank 63 in which fluid toner is stored, and is disposed in contact with the downstream side in the rotational direction of the developing roller 24 from the contact position with the photosensitive drum 11. Then, by rotating clockwise in FIG. 5, the moving direction is opposite to the contact position with the developing roller 24. A power supply device (voltage application device) 64 is connected to the cleaning roller 62. Further, a collecting electrode 65 is disposed to face the outer peripheral surface of the cleaning roller 62.

  Therefore, by applying a bias voltage to the cleaning roller 62 by the power supply device 64, the liquid toner remaining on the developing roller 24 can be removed by the cleaning roller 62 due to the electric field generated in the cleaning roller 62. Then, the toner removed by the cleaning roller 62 can be collected in the auxiliary tank 63 by the collecting electrode 65 and returned to the tank 21 through a return line (not shown). In this case, since the residual toner after cleaning passes through the electric field, the toner is aggregated to increase the viscosity and the fluidity is poor. Therefore, in order to collect and transport the liquid toner after cleaning, it is necessary to place a transport roller such as a spiral roller in the vicinity of the cleaning. However, in this embodiment, a part of the cleaning roller 62 is immersed in the reserve tank 63 in which the fluid toner is stored, and the fluidity is recovered by bringing the poorly fluid recovery and the toner into contact with the solvent-rich liquid toner. And can be directly collected in the reserve tank 63.

  In the developing device 61 of the present embodiment configured as described above, first, the supply roller 22 is rotated, the liquid toner stored in the tank 21 is pumped up by the supply roller 22, and the developing roller is passed through the leveling roller 23. 24, and a thin liquid toner layer is formed on the developing roller 24. At this time, by adjusting the bias voltage applied to the leveling roller 23 and the developing roller 24 by the power supply device 25, the film thickness of the liquid toner layer is adjusted by the electric field generated in the leveling roller 23 and the developing roller 24. Further, the charging device 51 performs corona discharge on the liquid toner on the developing roller 24 to bring the toner particles floating in the solvent into an aligned state in close contact with each other.

  Then, by bringing the liquid toner layer on the developing roller 24 close to the electrostatic latent image formed on the surface of the photosensitive drum 11, the liquid toner charged by electrostatic force is moved onto the photosensitive drum 11, A toner image is formed on the surface. At this time, since the liquid toner layer on the developing roller 24 is in an aligned state in which the toner particles are in close contact with each other, the liquid toner layer moves onto the photosensitive drum 11 while the toner particles are in close contact with the aligned state. A toner image having a uniform film thickness is formed on the drum 11.

  After the liquid toner layer is moved from the developing roller 24 to the photosensitive drum 11, unused liquid toner remains on the surface of the developing roller 24. Here, by applying a bias voltage to the cleaning roller 62 by the power supply device 64, the liquid toner remaining on the developing roller 24 is removed by the cleaning roller 62 due to an electric field generated in the cleaning roller 62. Then, the toner removed by the cleaning roller 62 is collected in the auxiliary tank 63 by the collecting electrode 65.

  As described above, in the developing device 61 according to the second exemplary embodiment, the tank 21 that stores liquid toner of a predetermined concentration, and the supply roller 22 that is partially immersed in the liquid toner in the tank 21 and can pump up the liquid toner. And a leveling roller 23 and a developing roller 24 to which liquid toner is delivered, and a cleaning roller 62 that is partially immersed in the liquid toner in the reserve tank 63 is provided in contact with the developing roller 24, A power supply device 64 is connected to the cleaning roller 62.

  Accordingly, the supply roller 22 draws up the liquid toner in the tank 21 and delivers it to the developing roller 24 via the leveling roller 23. At this time, a bias voltage is applied to the cleaning roller 62 by the power supply device 64, whereby the cleaning roller The liquid toner remaining on the developing roller 24 can be removed by the cleaning roller 62 due to the electric field generated at 62, and the toner recovery efficiency can be improved. Further, a collecting electrode 65 is disposed opposite to the outer peripheral surface of the cleaning roller 6, and the toner removed by the cleaning roller 62 can be collected in the spare tank 63 by the collecting electrode 65.

  In this case, the toner particles in the liquid toner on the developing roller 24 are applied by applying a bias voltage to the developing roller 24 by the power supply device 25 and charging the liquid toner supplied to the outer peripheral surface of the developing roller 24 by the charging device 51. Since the adhesion between them is high, the liquid toner on the developing roller 24 can be reliably removed by the electric field generated in the cleaning roller 62.

  FIG. 6 is a schematic configuration diagram illustrating a developing device according to Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the third embodiment, the developing device 71 includes a tank 21 in which liquid toner of a predetermined concentration is stored, a supply roller 22 that is partly immersed in the liquid toner in the tank 21 and can pump up the liquid toner, and this supply The leveling roller 23 is in contact with the roller 22, and the developing roller 24 is in contact with the leveling roller 23 and receives liquid toner. The developing roller 24 is in contact with the photosensitive drum 11.

  In the developing device 71 of this embodiment, a cleaning roller (cleaning member) 62 is provided in contact with the developing roller 24. A part of the cleaning roller 62 is immersed in a reserve tank 63 in which fluid toner is stored, and is disposed in contact with the downstream side in the rotation direction from the contact position of the developing roller 24 with the photosensitive drum 11. Then, by rotating clockwise in FIG. 5, the moving direction is opposite to the contact position with the developing roller 24. A power supply device (voltage application device) 64 is connected to the cleaning roller 62. Further, a collecting electrode 65 is disposed to face the outer peripheral surface of the cleaning roller 62.

  Further, a loosening roller 72 is provided in contact with the developing roller 24 on the upstream side in the rotational direction from the contact position of the cleaning roller 62. The unwinding roller 72 rotates in the clockwise direction in FIG. 6, so that the moving direction of the unwinding roller 72 is opposite to the contact position with the developing roller 24. A power supply device 64 is connected to the cleaning roller 62 and the loosening roller 72. The loosening roller 72 can be swung in the axial direction by a swinging device (not shown).

  Therefore, by applying a bias voltage to the loosening roller 72 and the cleaning roller 62 by the power supply device 64, the loosening roller 72 releases the liquid toner remaining on the developing roller 24, and the liquid toner is peeled off by the electric field generated in the loosening roller 72. The liquid toner on the developing roller 24 can be removed by the cleaning roller 62 by the electric field generated in the cleaning roller 62. Then, the toner removed by the cleaning roller 62 can be collected in the auxiliary tank 63 by the collecting electrode 65 and returned to the tank 21 through a return line (not shown).

  In the developing device 71 of the present embodiment configured as described above, first, the supply roller 22 is rotated, the liquid toner stored in the tank 21 is pumped up by the supply roller 22, and the developing roller is passed through the leveling roller 23. 24, and a thin liquid toner layer is formed on the developing roller 24. At this time, by adjusting the bias voltage applied to the leveling roller 23 and the developing roller 24 by the power supply device 25, the film thickness of the liquid toner layer is adjusted by the electric field generated in the leveling roller 23 and the developing roller 24. Further, the charging device 51 performs corona discharge on the liquid toner on the developing roller 24 to bring the toner particles floating in the solvent into an aligned state in close contact with each other.

  Then, by bringing the liquid toner layer on the developing roller 24 close to the electrostatic latent image formed on the surface of the photosensitive drum 11, the liquid toner charged by electrostatic force is moved onto the photosensitive drum 11, A toner image is formed on the surface. At this time, since the liquid toner layer on the developing roller 24 is in an aligned state in which the toner particles are in close contact with each other, the liquid toner layer moves onto the photosensitive drum 11 while the toner particles are in close contact with the aligned state. A toner image having a uniform film thickness is formed on the drum 11.

  After the liquid toner layer is moved from the developing roller 24 to the photosensitive drum 11, unused liquid toner remains on the surface of the developing roller 24. Here, by applying a bias voltage to the loosening roller 72 and the cleaning roller 62 by the power supply device 64, the loosening roller 72 releases the liquid toner remaining on the developing roller 24, and the liquid toner is removed by the electric field generated in the loosening roller 72. The liquid toner on the developing roller 24 is removed by the cleaning roller 62 by the electric field generated in the cleaning roller 62 to facilitate the peeling. Then, the toner removed by the cleaning roller 62 is collected in the auxiliary tank 63 by the collecting electrode 65. Further, the liquid toner remaining on the developing roller 24 can be properly removed by swinging the loosening roller 72 in the axial direction.

  As described above, in the developing device 71 according to the third embodiment, the tank 21 that stores liquid toner of a predetermined concentration, and the supply roller 22 that can partially pump the liquid toner by being immersed in the liquid toner in the tank 21. And a leveling roller 23 and a developing roller 24 to which liquid toner is delivered, and a cleaning roller 62 partially immersed in the liquid toner in the reserve tank 63 is provided in contact with the developing roller 24. A loosening roller 72 is provided upstream of the cleaning roller 62, and a power supply device 64 is connected to the cleaning roller 62 and the loosening roller 72.

  Accordingly, the supply roller 22 draws up the liquid toner in the tank 21 and delivers it to the developing roller 24 via the leveling roller 23. At this time, a bias voltage is applied to the loosening roller 72 and the cleaning roller 62 by the power supply device 64. Thus, after the liquid toner remaining on the developing roller 24 is loosened by the loosening roller 72, the liquid toner can be removed by the electric field generated in the cleaning roller 62, and the toner recovery efficiency can be improved.

  In this case, the toner particles in the liquid toner on the developing roller 24 are applied by applying a bias voltage to the developing roller 24 by the power supply device 25 and charging the liquid toner supplied to the outer peripheral surface of the developing roller 24 by the charging device 51. Since the adhesion force between them is high, the liquid toner on the developing roller 24 can be reliably removed by the loosening roller 82 and the cleaning roller 62.

  FIG. 7 is a schematic configuration diagram illustrating a developing device according to Embodiment 4 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the fourth embodiment, the developing device 81 includes a tank 21 in which liquid toner of a predetermined concentration is stored, a supply roller 22 that is partly immersed in the liquid toner in the tank 21 and can pump up the liquid toner, and this supply The leveling roller 23 is in contact with the roller 22, and the developing roller 24 is in contact with the leveling roller 23 and receives liquid toner. The developing roller 24 is in contact with the photosensitive drum 11.

  In the developing device 81 of this embodiment, a cleaning blade (cleaning member) 82 is provided for the developing roller 24. The cleaning blade 82 is made of urethane, has a tip portion that contacts the developing roller 24, and a base end portion that is immersed in a reserve tank 83 that stores fluid toner, and is opposed to the photosensitive drum 11 in the developing roller 24. It arrange | positions facing the downstream of the rotation direction rather than the contact position. Further, a loosening roller 72 is provided in contact with the developing roller 24 on the upstream side in the rotational direction from the contact position of the cleaning blade 82. The unwinding roller 72 rotates in the clockwise direction in FIG. 7, so that the moving direction is opposite to the contact position with the developing roller 24. A power supply device 64 is connected to the cleaning blade 82 and the loosening roller 72.

  Accordingly, by applying a bias voltage to the loosening roller 72 and the cleaning blade 82 by the power supply device 64, the loosening roller 72 releases the liquid toner remaining on the developing roller 24, and the liquid toner is peeled off by the electric field generated in the loosening roller 72. The liquid toner on the developing roller 24 can be removed by the cleaning blade 82 by the electric field generated in the cleaning blade 82, collected in the spare tank 63, and returned to the tank 21 through a return line (not shown).

  In the developing device 81 of the present embodiment configured as described above, first, the supply roller 22 is rotated, the liquid toner stored in the tank 21 is pumped up by the supply roller 22, and the developing roller is passed through the leveling roller 23. 24, and a thin liquid toner layer is formed on the developing roller 24. At this time, by adjusting the bias voltage applied to the leveling roller 23 and the developing roller 24 by the power supply device 25, the film thickness of the liquid toner layer is adjusted by the electric field generated in the leveling roller 23 and the developing roller 24. Further, the charging device 51 performs corona discharge on the liquid toner on the developing roller 24, thereby bringing the toner particles floating in the solvent into an intimately aligned state.

  Then, by bringing the liquid toner layer on the developing roller 24 close to the electrostatic latent image formed on the surface of the photosensitive drum 11, the liquid toner charged by electrostatic force is moved onto the photosensitive drum 11, A toner image is formed on the surface. At this time, since the liquid toner layer on the developing roller 24 is in an aligned state in which the toner particles are in close contact with each other, the liquid toner layer moves onto the photosensitive drum 11 while the toner particles are in close contact with the aligned state. A toner image having a uniform film thickness is formed on the drum 11.

  After the liquid toner layer is moved from the developing roller 24 to the photosensitive drum 11, unused liquid toner remains on the surface of the developing roller 24. Here, by applying a bias voltage to the loosening roller 72 and the cleaning blade 82 by the power supply device 64, the loosening roller 72 releases the liquid toner remaining on the developing roller 24, and the liquid toner is removed by the electric field generated in the loosening roller 72. The liquid toner on the developing roller 24 is removed by the cleaning blade 82 by the electric field generated in the cleaning blade 82 to facilitate peeling, and the removed toner is collected in the reserve tank 63.

  As described above, in the developing device 81 according to the fourth embodiment, the tank 21 that stores liquid toner of a predetermined concentration, and the supply roller 22 that can partially pump the liquid toner by being immersed in the liquid toner in the tank 21. And a leveling roller 23 and a developing roller 24 to which the liquid toner is transferred. A cleaning blade 82 whose base end is immersed in the liquid toner in the reserve tank 63 is provided on the developing roller 24. A loosening roller 72 is provided upstream of the cleaning blade 82, and a power supply device 64 is connected to the cleaning blade 82 and the loosening roller 72.

  Accordingly, the supply roller 22 draws up the liquid toner in the tank 21 and delivers it to the developing roller 24 via the leveling roller 23. At this time, a bias voltage is applied to the loosening roller 72 and the cleaning blade 82 by the power supply device 64. Thus, after the liquid toner remaining on the developing roller 24 is loosened by the loosening roller 72, the liquid toner can be removed by the electric field generated in the cleaning blade 82, and the toner recovery efficiency can be improved.

  In the second to fourth embodiments described above, the preliminary tanks 63 and 83 in which a part of the cleaning roller 62 and the cleaning blade 82 are immersed in the liquid toner are provided. However, a part of the cleaning roller 62 and the cleaning blade 82 is a tank. It may be soaked in 21 liquid toner. In the second embodiment, only the cleaning roller 62 is provided. However, only the cleaning blade 82 described in the fourth embodiment may be provided.

  In each of the above-described embodiments, the developing device 14 includes the tank 21, the supply roller 22, the leveling roller 23, and the developing roller 24. However, the developing device 14 includes at least the tank 21, the supply roller 22, and the developing roller 24. On the other hand, a plurality of rollers may be provided between the supply roller 22 and the developing roller 24, and a plurality of leveling rollers 23 may be further provided. The power supply device 64 is connected to the loosening roller 72. However, for example, a rubber roller such as a sponge roller may be used, and the toner fixed on the surface of the developing roller 24 may be physically released from the surface. As long as it can be performed, it has a function to assist in order to make the removal function by the cleaning operation in the next process more complete.

  In each of the above-described embodiments, the electrophotographic apparatus includes the photosensitive drum 11, the charging device 12, the exposure device 13, the developing device 14, the transfer device 15, and the fixing device 16. However, the same applies to four-color printing. It is possible by repeating this process and 4 times.

  The developing device and the electrophotographic apparatus according to the present invention aim to improve the quality by uniformizing the film thickness of the liquid toner layer moved from the developing roller to the photosensitive drum. Can also be applied.

1 is a schematic configuration diagram of an electrophotographic apparatus to which a developing device according to Embodiment 1 of the present invention is applied. 3 is a front view of an anilox roller in the developing device of Embodiment 1. FIG. 6 is a schematic diagram illustrating an operation in the developing device of Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating a movement state of toner particles by the developing device of Example 1. FIG. 3 is a schematic diagram illustrating a movement state of toner particles by the developing device of Example 1. FIG. 3 is a schematic diagram illustrating a movement state of toner particles by the developing device of Example 1. It is a schematic block diagram showing the developing device which concerns on Example 2 of this invention. It is a schematic block diagram showing the developing device concerning Example 3 of this invention. It is a schematic block diagram showing the developing device which concerns on Example 4 of this invention.

Explanation of symbols

11 Photosensitive drum 12 Charging device (photosensitive drum charging device)
DESCRIPTION OF SYMBOLS 13 Exposure apparatus 14, 61, 71, 81 Developing apparatus 15 Transfer apparatus 16 Fixing apparatus 21 Tank 22 Supply roller 23 Leveling roller 24 Developing roller 25, 53, 64 Power supply apparatus (voltage application apparatus)
27 toner density adjusting device 28 toner density measuring device 29 control device 41 transfer drum 42 secondary transfer roller 51 charging device (toner charging device)
52 Tungsten wire (discharge electrode)
53 Housing 62 Cleaning roller (cleaning member)
63,83 Spare tank 65 Collection electrode 82 Cleaning blade (cleaning member)

Claims (10)

  A tank in which liquid toner of a predetermined concentration is stored, a supply roller that is partly immersed in the liquid toner in the tank to pump up the liquid toner, a developing roller to which the liquid toner is transferred from the supply roller, A developing device comprising: a voltage applying device that applies a bias voltage to the developing roller; and a charging device that charges liquid toner supplied to the outer peripheral surface of the developing roller.   The developing device according to claim 1, wherein the charging device includes a discharge electrode and a housing that surrounds the discharge electrode and has an opening on one side thereof, and the opening of the housing is formed on an outer peripheral surface of the developing roller. A developing device arranged to face each other.   3. The developing device according to claim 1, wherein a leveling roller is disposed between the supply roller and the development roller, and a roller moving direction at a contact portion between the supply roller and the leveling roller is the same direction. And a roller moving direction at a contact portion between the leveling roller and the developing roller is set in a reverse direction.   4. The developing device according to claim 1, wherein a cleaning member for removing liquid toner remaining on the developing roller is provided, and a voltage applying device for applying a bias voltage is connected to the cleaning member. A developing device.   5. The developing device according to claim 4, wherein the cleaning member is a cleaning roller or a cleaning blade that is in contact with the developing roller.   6. The developing device according to claim 4, wherein a collecting electrode is provided to face the outer peripheral surface of the cleaning member.   7. The developing device according to claim 4, wherein a part of the cleaning member is immersed in a liquid toner. 8.   8. The developing device according to claim 4, wherein a loosening roller that is in contact with the developing roller is provided upstream of the cleaning member in the rotating direction of the developing roller. apparatus.   9. The developing device according to claim 8, wherein the loosening roller is supported by an oscillating device so as to be swingable in an axial direction.   A tank in which liquid toner of a predetermined concentration is stored, a supply roller that is partly immersed in the liquid toner in the tank to pump up the liquid toner, a developing roller to which the liquid toner is transferred from the supply roller, A voltage applying device that applies a bias voltage to the developing roller, a toner charging device that charges the liquid toner supplied to the outer peripheral surface of the developing roller, a photosensitive drum that contacts the developing roller and receives the liquid toner, A photosensitive drum charging device that charges the outer peripheral surface of the photosensitive drum; an exposure device that exposes an image on the charged photosensitive drum; a transfer drum on which a toner image is primarily transferred in contact with the photosensitive drum; and the transfer drum A secondary transfer roll for secondary transfer of the toner image onto the paper by sandwiching the paper between the toner and a fixing for fixing the toner image secondary transferred onto the paper Electrophotographic apparatus being characterized in that comprises a location.

Images