JP5156369B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus provided with a liquid developing device used for an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system.

  2. Description of the Related Art Conventionally, as a method for forming an image on a sheet, a liquid developing apparatus using a liquid developer in which toner is mixed in a carrier liquid is known. The image forming apparatus applied to the liquid developing device supplies toner to the photosensitive member from the liquid developing device, forms a toner image from the electrostatic latent image on the photosensitive member, and transfers the toner image to a sheet. A fixing unit that fixes an image formed by the image forming unit on a sheet, and a discharge unit that discharges the sheet on which the image is fixed by the fixing unit. In this image forming apparatus, an image is formed on a sheet by an image forming unit, and the image is fixed by a fixing unit. The sheet on which the image is fixed is discharged from the discharge unit.

  In order to form a good image with the liquid developing device, it is necessary to store the liquid amount of the liquid developer and the toner concentration in the developing tank in an appropriate state. In Patent Document 1, the amount of liquid developer in a developing tank is detected by a developing solution amount detecting means, and a mother liquid in which toner particles are dispersed is replenished to the developing tank based on the detection result. The developer concentration is kept constant, and the toner concentration in the liquid developer is detected by the developer concentration detecting means. When the toner concentration falls to a predetermined density lower limit allowable value based on the detection result, the concentration is increased. A constant amount of concentrated toner is replenished into the developing tank by the toner replenishing means.

  Here, in general, in a liquid developing device, in the process of forming a toner image on a photosensitive member, residual developer on a developing roller or a developing tank that has not been used for development is collected and reused or discarded. For example, Patent Document 2 includes a developing unit that forms a toner image using a liquid developer stored in a developing tank, and a transfer unit that transfers the toner image formed by the developing unit to a sheet. The remaining liquid developer is collected and the degree of deterioration of the liquid developer is determined. If it is determined that the degree of deterioration is low according to the result of the determination, the transported liquid developer is used again for development, while if it is determined that the degree of deterioration of the liquid developer is high, the liquid developer has been transported. The liquid developer is disposed outside the liquid developing apparatus.

However, in the above-described prior art, when the image forming apparatus repeats image formation over a long period of time, a developing device such as a developing roller and a developing tank, a transport pipe that supplies the liquid developer to the developing device, and reuse of the liquid developer Toner adheres to the inner wall of the conveyance section such as a conveyance switching valve for disposal. When the toner attached to such a developing device or the transporting portion deteriorates due to secular change, and the deteriorated toner is peeled off from the inner wall or the like and transported to the developing device and used for development, an image in which fogging occurs or the contrast is lowered. There is a risk of becoming. Further, the adhered toner may be solidified and clogged on the inner wall, which may hinder the supply of the liquid developer.
JP-A-8-76604 (paragraphs [0012] to [0020], [0026], FIG. 3) JP 2007-199530 A (paragraphs [0012], [0025], [0026], FIG. 1)

  The present invention has been made to solve the above-described problems, and removes toner adhering to an inner wall of a developing device, a transport pipe for supplying a liquid developer to the developing device, a switching valve, and the like, An object of the present invention is to provide an image forming apparatus in which a liquid developer is favorably conveyed and supplied.

  In order to achieve the above object, the present invention provides a developer for developing an electrostatic latent image by supplying a liquid developer in which toner and a carrier liquid are mixed to an image carrier, and residual development remaining after development of the developer. A developer generation unit that stores the agent and adjusts the toner density; a carrier tank that stores carrier liquid and is connected to the developer generation unit; and a toner tank that stores toner and is connected to the developer generation unit; An image forming apparatus comprising: a collecting and conveying unit that conveys the residual developer from the developing unit to the developer generating unit; and a supply and conveying unit that conveys the liquid developer from the developer generating unit to the developing unit. A switching unit that includes a waste liquid tank that collects the cleaning liquid that has cleaned the developer, and switches between transport of the liquid from the developer to the developer generator and transport of the liquid from the developer to the waste liquid tank. The collection transport It is characterized in that provided in the.

  According to this configuration, at the time of image formation, the switching unit is switched so that the liquid is conveyed from the developing device to the developer generating unit. The liquid developer remaining in the developing unit without being supplied to the image carrier after the image forming operation is transported to the recovery transport unit, and is recovered to the developer generation unit according to switching of the switching unit. Depending on the detection result of the toner concentration in the developer generating unit, when the carrier liquid is supplied from the carrier tank to the developer generating unit or the toner having a high concentration is supplied from the toner tank, and the toner concentration is adjusted. The liquid developer is transported to the supply transport unit and supplied to the developing device. At the time of cleaning, the switching unit is switched so that the liquid is conveyed from the developing device to the waste liquid tank. The cleaning liquid that has cleaned the inside of the developing device is conveyed from the developing device to the collecting and conveying unit, and is collected in the waste liquid tank according to the switching of the switching unit.

  Further, in the invention according to claim 2, the cleaning liquid is stored in the carrier tank when the developing device is cleaned, and the cleaning liquid includes the developer generation unit, the supply transport unit, the developing unit, and the developing unit. It is sequentially conveyed to a collection conveyance unit and collected in the waste liquid tank. According to this configuration, the cleaning liquid stored in the carrier tank is the same as the liquid developer transport path at the time of image formation when the switching unit is switched so that the liquid is transported from the developing device to the waste liquid tank. As described above, the toner is transported from the developer generation unit to the supply transport path, the developing device, and the recovery transport path, and is collected in the waste liquid tank.

  According to a third aspect of the present invention, the cleaning liquid is the carrier liquid. According to this configuration, the carrier liquid stored in the carrier tank is transported from the developer generation unit to the supply transport path, the developing device, and the recovery transport path, and is collected in the waste liquid tank.

  According to a fourth aspect of the present invention, the apparatus includes a cleaning liquid tank that stores the cleaning liquid, and the cleaning liquid tank is connected to the developer generating unit so as to be able to transport the cleaning liquid. According to this configuration, at the time of cleaning, the cleaning liquid stored in the cleaning liquid tank is transported from the developer generation unit to the supply transport path, the developing device, and the recovery transport path, and is collected in the waste liquid tank.

  According to the first aspect of the present invention, at the time of image formation, the switching unit is switched so that the liquid is conveyed from the developing device to the developer generating unit. The liquid developer remaining in the developing unit without being supplied to the image carrier after the image forming operation is transported to the recovery transport unit, and is recovered to the developer generation unit according to switching of the switching unit. Depending on the detection result of the toner concentration in the developer generating unit, when the carrier liquid is supplied from the carrier tank to the developer generating unit or the toner having a high concentration is supplied from the toner tank, and the toner concentration is adjusted. The liquid developer is transported to the supply transport unit and supplied to the developing device. At the time of cleaning, the switching unit is switched so that the liquid is conveyed from the developing device to the waste liquid tank. The cleaning liquid that has cleaned the inside of the developing device is conveyed from the developing device to the collecting and conveying unit, and is collected in the waste liquid tank according to the switching of the switching unit. Therefore, the toner adhering to the liquid developer conveyance path and the storage unit in the developing unit and the collection conveyance unit is removed, and the liquid developer is conveyed and supplied to the inside of the development unit and the liquid developer circulation device in the image formation. Can do.

  According to the second aspect of the present invention, the cleaning liquid stored in the carrier tank is the liquid at the time of image formation at the time of cleaning when the switching unit is switched so that the liquid is conveyed from the developing device to the waste liquid tank. In the same way as the developer transport path, it is transported from the developer generator to the supply transport path, the developer, and the recovery transport path, and collected in the waste liquid tank. Accordingly, the cleaning liquid is collected, the apparatus configuration is not complicated, and the developing device, the developer generating unit, and the supply and collection conveyance path can be cleaned by a simple switching operation of the switching unit.

  According to the third aspect of the present invention, the carrier liquid stored in the carrier tank is transported from the developer generator to the supply transport path, the developing device, and the recovery transport path, and is recovered in the waste liquid tank. Therefore, complicated operations such as refilling the cleaning liquid can be made unnecessary.

  According to the fourth aspect of the present invention, at the time of cleaning, the cleaning liquid stored in the cleaning liquid tank is transported from the developer generation unit to the supply transport path, the developing device, and the recovery transport path, and is collected in the waste liquid tank. Therefore, it is possible to remove the toner adhering to the developing device, the developer generating unit, and the supply and recovery conveyance path.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. The embodiment of the present invention shows the most preferable form of the invention, and the use of the invention and the terms shown here are not limited thereto.

(First embodiment)
A schematic configuration of a color printer 1 as an image forming apparatus according to an embodiment of the present disclosure will be described with reference to FIGS. 1 is a schematic cross-sectional view showing the overall configuration of the color printer 1, FIG. 2 is a schematic cross-sectional view of the color printer 1 excluding the liquid developer circulating device, and FIG. 3 is an enlarged view of one of the image forming units. It is sectional drawing shown.

  As shown in FIG. 1, a color printer 1 is disposed in an upper main body 1A that stores various units and parts for image formation, and a lower portion of the upper main body 1A, and a liquid developer circulation for each color. It is comprised from the lower main-body part 1B in which apparatus LY, LM, LC, LB is accommodated. Here, the piping connecting the upper main body 1A and the lower main body 1B is not shown.

  As shown in FIG. 2, the upper main body 1 </ b> A is formed by a tandem image forming unit 2 that forms a toner image based on image data, a paper storage unit 3 that stores paper, and an image forming unit 2. A secondary transfer unit 4 that transfers the toner image onto the paper, a fixing unit 5 that fixes the transferred toner image on the paper, a discharge unit 6 that discharges the fixed paper, and a paper storage unit 3. And a paper transport unit 7 for transporting paper from the discharge unit 6 to the discharge unit 6.

  The image forming unit 2 includes an intermediate transfer belt 21, a cleaning unit 22 for the intermediate transfer belt 21, and an image forming unit corresponding to each of yellow (Y), magenta (M), cyan (C), and black (Bk). FY, FM, FC, and FB.

  The intermediate transfer belt 21 is a belt-like member having an endless shape, that is, a loop shape, which is wider than a sheet having the maximum length in the direction perpendicular to the usable sheet conveying direction and having conductivity. 2 is driven to circulate clockwise. In the circulation driving of the intermediate transfer belt 21, the surface facing outward is hereinafter referred to as a front surface, and the other surface is referred to as a back surface.

  Four image forming units FY, FM, FC, and FB are arranged near the intermediate transfer belt 21 and arranged between the cleaning unit 22 and the secondary transfer unit 4 of the intermediate transfer belt 21. Note that the order of arrangement of the image forming units FY, FM, FC, and FB is not limited to this, but this arrangement is preferable in consideration of the influence of the color mixture on the completed image.

  The image forming units FY, FM, FC, and FB include a photosensitive drum 10, a charger 11, an LED exposure device 12, a developing device 14, a primary transfer roller 20, a cleaning unit 26, and a charge removal device 13. And a carrier liquid removing roller 30. Further, among the image forming units, the image forming unit FB located closest to the secondary transfer unit 4 is not provided with the carrier liquid removal roller 30, but the other configurations are the same.

  Corresponding to the image forming units FY, FM, FC, FB, liquid developer circulating devices LY, LM, LC, LB are provided, respectively, so that supply and recovery of the liquid developers of the respective colors are performed. Yes. The liquid developer circulating devices LY, LM, LC, and LB will be described in detail later.

  The photosensitive drum 10 is a cylindrical member, and can carry a toner image including toner charged on its surface (charged positively in this embodiment). The photosensitive drum 10 is a member that can rotate counterclockwise in FIGS. 2 and 3.

  The charger 11 can uniformly charge the surface of the photosensitive drum 10. The exposure device 12 has a light source such as an LED and irradiates light onto the surface of the uniformly charged photoreceptor drum 10 in accordance with image data input from an external device. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 10.

  The developing device 14 holds the liquid developer containing the toner and the liquid carrier so as to face the electrostatic latent image on the surface of the photosensitive drum 10, thereby attaching the toner to the electrostatic latent image. Thereby, the electrostatic latent image is developed as a toner image.

  As shown in FIG. 3, the developing device 14 includes a developing container 140, a developing roller 141, a supply roller 142, a support roller 143, a supply roller blade 144, a development cleaning blade 145, a developer recovery unit 146, and a development roller charger 147. Including.

  The developing container 140 is a container that receives a liquid developer including toner particles and a liquid carrier. As will be described later, the liquid developer is supplied from the supply nozzle 278 into the developing container 140 in a state where the density adjustment between the toner and the carrier has been performed in advance. The liquid developer is supplied toward the nip portion between the supply roller 142 and the support roller 143, and the surplus portion falls below the support roller 143 and is stored at the bottom of the developing container 140. The stored liquid developer is collected by the liquid developer circulating device through the pipe 96 (see FIG. 4).

  The support roller 143 is disposed substantially at the center of the developing container 140, and abuts against the supply roller 142 in a manner to be supported from below to form a nip portion. The supply roller 142 is arranged not diagonally above the support roller 143 but obliquely upward in the direction away from the supply nozzle 278, and a groove for holding the liquid developer is provided on the peripheral surface thereof. As indicated by dotted arrows in the figure, the support roller 143 rotates counterclockwise and the supply roller 142 rotates clockwise.

  The liquid developer supplied from the supply nozzle 278 is temporarily retained on the upstream side in the rotation direction of the nip portion, and is moved upward while being held in the groove of the supply roller 142 as both rollers 142 and 143 rotate. Carried to. The supply roller blade 144 is in pressure contact with the peripheral surface of the supply roller 142 and regulates the amount of liquid developer held by the supply roller 142 to be a predetermined amount. Excess liquid developer scraped off by the supply roller blade 144 is received at the bottom of the developing container 140.

  The developing roller 141 is disposed in the upper opening of the developing container 140 so as to be in contact with the supply roller 142. The developing roller 141 is rotated in the same direction as the supply roller 142, whereby the liquid developer held on the peripheral surface of the supply roller 142 is transferred to the peripheral surface of the developing roller 141. Since the layer thickness of the liquid developer on the supply roller 142 is regulated to a predetermined value, the layer thickness of the liquid developer layer formed on the surface of the developing roller 141 is also maintained at a predetermined value.

  The developing roller charger 147 moves the toner in the developer layer carried on the developing roller 141 to the surface side of the developing roller 141 by applying a charging potential having the same polarity as the charging polarity of the toner, thereby improving the developing efficiency. It fulfills the action of The developing roller charger 147 faces the circumferential surface of the developing roller 141 on the downstream side in the rotation direction of the developing roller 141 in contact with the supply roller 142 and on the upstream side in contact with the photosensitive drum 10. It is provided as follows.

  The developing roller 141 is in contact with the photosensitive drum 10, and a toner image corresponding to the image data instructed to form is generated by the potential difference between the electrostatic latent image potential on the surface of the photosensitive drum 10 and the developing bias applied to the developing roller 141. It is formed on the surface of the photosensitive drum 10 (development operation).

  The developing cleaning blade 145 is disposed so as to contact the downstream side in the rotation direction of the contact portion of the developing roller 141 with the photosensitive drum 10, and the liquid development on the surface of the developing roller 141 that has completed the developing operation on the photosensitive drum 10 is performed. Remove the agent.

  The developer recovery unit 146 recovers the liquid developer removed by the developer cleaning blade 145 and sends the liquid developer to the first pipe 81 of the liquid developer circulating device by the screw roller 149. The liquid developer flows down along the surface of the development cleaning blade 145. Since the viscosity of the liquid developer is high, the developer recovery unit 146 is provided with a feed roller 148 that assists in feeding the liquid developer. .

  The primary transfer roller 20 is disposed on the back surface of the intermediate transfer belt 21 so as to face the photosensitive drum 10. A voltage having a polarity opposite to that of the toner in the toner image (minus in this embodiment) is applied to the primary transfer roller 20 from a power source (not shown). That is, the primary transfer roller 20 applies a voltage having a polarity opposite to that of the toner to the intermediate transfer belt 21 at a position in contact with the intermediate transfer belt 21. Since the intermediate transfer belt 21 has conductivity, the applied voltage attracts toner to the surface side of the intermediate transfer belt 21 and its periphery.

  The cleaning unit 26 is for cleaning the liquid developer remaining without being transferred from the photosensitive drum 10 to the paper, and includes a residual developer conveying screw 261 and a cleaning blade 262. The residual developer conveying screw 261 is a member that is scraped off by the cleaning blade 262 and conveys the residual developer stored in the cleaning unit 26 to the outside of the cleaning unit, and is disposed in the cleaning unit 26. Yes.

  The cleaning blade 262 is a member for scraping off the liquid developer remaining on the surface of the photosensitive drum 10 and is a plate-like member extending in the direction of the rotation axis of the photosensitive drum 10. The end of the cleaning blade 262 is in sliding contact with the surface of the photosensitive drum 10, and scrapes off the liquid developer remaining on the photosensitive drum 10 as the photosensitive drum 10 rotates. The static eliminator 13 has a light source for static elimination, and removes the liquid developer by the cleaning blade 262 and removes the surface of the photosensitive drum 10 with light from the light source in preparation for the next round of image formation.

  The carrier liquid removal roller 30 is a substantially cylindrical member that can rotate in the same direction as the photosensitive drum 10 around a rotational axis parallel to the rotational axis of the photosensitive drum 10. The carrier liquid removing roller 30 is disposed on the side where the secondary transfer unit 4 (see FIG. 2) is disposed with respect to the position where the photosensitive drum 10 and the intermediate transfer belt 21 are in contact with each other. A member for removing the carrier liquid from the surface.

  Returning to FIG. 2, the paper storage unit 3 is a part for storing a paper for fixing a toner image, and is disposed at the lower part of the upper main body 1 </ b> A. The paper storage unit 3 has a paper feed cassette that stores paper. The secondary transfer unit 4 is a part that transfers the toner image formed on the intermediate transfer belt 21 to a sheet, and is disposed opposite to the support roller 41 that supports the intermediate transfer belt 21 and the support roller 41. And a secondary transfer roller 42. The fixing unit 5 is a part for fixing the toner image on the sheet, and is disposed on the upper side of the secondary transfer unit 4. The fixing unit 5 includes a heating roller 51 and a pressure roller 52 disposed to face the heating roller 51. The discharge unit 6 is a portion from which the paper on which the toner image has been fixed by the fixing unit 5 is discharged, and is disposed at the top of the color printer 1. The paper transport unit 7 includes a plurality of transport roller pairs, and transports the paper from the paper storage unit 3 to the secondary transfer unit 4, the fixing unit 5, and the discharge unit 6.

  FIG. 4 shows an outline of the entire liquid developer circulating device LY. The other liquid developer circulating devices LM, LC, LB have the same configuration. This liquid developer circulation device LY circulates the residual developer (mixture of toner and carrier liquid) scraped from the surface of the developing roller 141 by the developing cleaning blade 145 after supplying the liquid developer to the photosensitive drum 10. It is a device to let you reuse.

  The liquid developer circulation device LY includes a residual developer tank 271, a developer container 272 as a developer generation unit, a solid content concentration detection unit 273, a carrier tank 274, a toner tank 275, a stirring member 276, and a developer reserve tank 277. , A supply nozzle 278, a carrier separator 279, a plurality of pumps P1 to P10, a plurality of pipes 81 to 88, a three-way valve V1, and a waste liquid tank 281.

  The liquid developer scraped from the surface of the developing roller 141 by the developing cleaning blade 145 after supplying the toner to the photosensitive drum 10 is conveyed to the residual developer tank 271 through the first pipe 81 by driving the first pump P1. Is done. Further, the liquid developer collected in the developing container 140 without being supplied from the supply roller 142 to the developing roller 141 in the developing container 140 is conveyed to the residual developer tank 271 through the pipe 96 by driving the pump P8.

  The residual developer tank 271 is a tank that is connected to the developing device 14 via the first pipe 81 and the pipe 96 and can store the liquid developer recovered from the developing device 14 side. A first pump P1 and a pump P8 are attached in the middle of the first pipe 81 and the pipe 96, respectively.

  The developer container 272 is connected to the residual developer tank 271. The developer container 272 adjusts the toner concentration to an appropriate range by adding a developer having a toner concentration higher than that of the developer used in the developing device 14 or a carrier liquid to the residual developer. The toner density is adjusted to an appropriate range. In addition, the liquid developer amount in the developer container 272 is constantly detected by the liquid amount detector, and the liquid amount of the liquid developer is adjusted to an appropriate range. The adjusted liquid developer is stirred by the stirring member 276 and supplied to the developing device 14. Replenishment to the developing device 14 will be described later.

  In order to collect the residual developer from the residual developer tank 271, the developer container 272 is connected to the residual developer tank 271 via the second pipe 82, and the second pipe 82 is connected to the second pipe 82. A pump P2 is attached. The liquid developer in the residual developer tank 271 is conveyed to the developer storage container 272 through the second pipe 82 by driving the second pump P2. The first pipe 81, the second pipe 82, the pipe 96, the first pump P1, the second pump P2, the pump P8, and the residual developer tank 271 constitute a recovery conveyance unit.

  The solid content concentration detector 273 is for detecting the toner concentration of the liquid developer stored in the developer storage container 272. A solid concentration detector 273 is connected to an annular circulation pipe 85 connected to the developer container 272. A pump P5 is attached to the circulation pipe 85. The liquid developer in the developer container 272 is guided from the inlet end of the circulation pipe 85 to the solid content detector 273 by driving the pump P5, and then returned to the developer container 272 from the outlet end of the circulation pipe 85. It is.

  The toner tank 275 is a tank that stores a liquid developer having a toner concentration higher than that of the developer used in the developing device 14. When the solid concentration detector 273 determines that the toner concentration in the developer container 272 is lower than the appropriate range, a liquid developer having a high toner concentration is transferred from the toner tank 275 into the developer container 272. The toner concentration of the liquid developer in the developer container 272 is increased. The toner tank 275 and the developer container 272 are connected by a toner pipe 86, and the supply of the liquid developer to the developer container 272 is executed by driving a pump P6 provided in the middle of the toner pipe 86. Is done.

  The carrier tank 274 is a tank that stores a carrier liquid. When the solid content detector 273 determines that the toner concentration in the developer container 272 is higher than the appropriate range, carrier liquid is supplied from the carrier tank 274 into the developer container 272, and the developer. The toner concentration of the liquid developer in the container 272 is lowered. The carrier tank 274 and the developer container 272 are connected by a carrier pipe 87, and the supply of the carrier liquid to the developer container 272 is executed by driving a pump P7 provided in the middle of the carrier pipe 87. The

  The developer reserve tank 277 is a tank that stores a liquid developer to be supplied to the developing device 14. The developer reserve tank 277 is connected to the developer container 272 by a third pipe 83, and the liquid developer is removed from the developer container 272 by driving a third pump P 3 provided in the middle of the third pipe 83. Receive the supply.

  The supply nozzle 278 is a member for supplying the liquid developer stored in the developer reserve tank 277 to the developing device 14 (developing container 140). The supply nozzle 278 and the developer reserve tank 277 are connected by a fourth pipe 84, and the supply of the liquid developer from the developer reserve tank 277 to the developing device 14 is performed by a fourth pump attached to the fourth pipe 84. This is executed by driving P4. The third pipe 83, the fourth pipe 84, the third pump P3, the fourth pump P4, and the developer reserve tank 277 described above constitute a supply conveyance unit.

  The carrier separator 279 separates and extracts the carrier liquid from the remaining developer collected by the cleaning unit 26. The cleaning unit 26 and the carrier separator 279 are connected by a pipe 881 to which a pump P9 is attached. The remaining amount of developer in the cleaning unit 26 is sent to the carrier separator 279 by driving the pump P9. A pipe 882 to which a pump P10 is attached is provided between the carrier separator 279 and the carrier tank 274. The carrier liquid extracted by the carrier separator 279 is sent to the carrier tank 274 by driving the pump P10.

  The waste liquid tank 281 is a tank for storing a cleaning liquid used for cleaning the inside of the developing device 14 and the liquid developer circulating device LY. The waste liquid tank 281 and the second pipe 82 are connected by a waste liquid pipe 88 via a three-way valve V1 as a switching unit.

  The three-way valve V1 is provided in the middle of the second pipe 82 connecting the second pump P2 and the developer container 272, and transports the liquid developer in the residual developer tank 271 to the developer container 272, and residual development. The cleaning liquid in the agent tank 271 can be switched to the waste liquid tank 281. For this switching, the liquid transport from the residual developer tank 271 to the developer storage container 272 is hereinafter referred to as the developer storage container side, and the liquid transport from the residual developer tank 271 to the waste liquid tank 281 is described below. This is called the waste liquid tank side. Recovery of the cleaning liquid used for cleaning is performed by switching the three-way valve V1 to the waste liquid tank side and driving the second pump P2.

  The driving of the pumps P1 to P10 and the switching of the three-way valve V1 are controlled by the control unit 90. The control unit 90 includes a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read Only Memory) that stores each control program, and a RAM (Random Access Memory) that temporarily stores data such as arithmetic processing and control processing. Etc.

  FIG. 5 is a block diagram illustrating a functional configuration of the control unit 90. The control unit 90 includes a valve control unit 92, a liquid level determination unit 93, and a pump control unit 94.

  The valve control unit 92 gives a switching signal for switching the valve between the developer container side and the waste liquid tank side to the three-way valve V1, and controls the switching of the valve.

  The pump control unit 94 gives a drive or stop control signal to the pumps P1 to P10 to control its operation. Based on the switching control of the three-way valve V1 by the valve control unit 92, the determination result by the liquid level determination unit 93, and the determination result of the toner concentration by the solid content concentration detector 273, the pump control unit 94 relates to these pumps. To control the operation.

  First, an image forming operation of the wet color printer 1 according to the present embodiment will be described with reference to FIGS. Upon receiving an image formation instruction from a personal computer (not shown) connected to the color printer 1, the color printer 1 converts the toner images of the respective colors corresponding to the image data for which the creation instruction has been received into image forming units FY, FM, FC. , FB. Specifically, an electrostatic latent image based on image data is formed on the photosensitive drum 10, and a liquid developer is supplied to the electrostatic latent image from the developing device 14. The image formed by each image forming unit in this way is transferred to the intermediate transfer belt 21 and is superimposed on the intermediate transfer belt 21 to form a color toner image.

  In synchronization with the formation of the color toner image, the paper stored in the paper storage unit 3 is taken out from the paper storage unit 3 one by one by a paper feeding device (not shown), and is transported along the paper transport unit 7. The Then, the sheet is sent to the secondary transfer unit 4 in synchronization with the primary transfer to the intermediate transfer belt 21, and the color toner image on the intermediate transfer belt 21 is secondarily transferred to the sheet by the secondary transfer unit 4.

  The sheet on which the color toner image is transferred is further conveyed to the fixing unit 5 where heat and pressure are applied, and the color toner image is fixed on the sheet. Further, the sheet is discharged outside the color printer 1 by the discharge unit 6. The toner remaining on the intermediate transfer belt 21 after the secondary transfer is removed from the intermediate transfer belt 21 by the cleaning unit 22 of the intermediate transfer belt 21.

  Next, the operation of supplying the liquid developer to the developing device 14, that is, the operation of circulating the liquid developer will be described with reference to FIGS.

  The liquid developer remaining on the developing roller 141 without being supplied to the photosensitive drum 10 during the image forming operation is scraped off by the developing cleaning blade 145 and collected in the residual developer tank 271 through the first pipe 81. . Further, the liquid developer collected in the developing container 140 without being supplied from the supply roller 142 to the developing roller 141 is also collected in the residual developer tank 271 through the pipe 96. Further, the carrier liquid extracted by the carrier separator 279 from the remaining developer collected by the cleaning unit 26 is collected in the carrier tank 274. The pump controller 94 drives the first pump P1, the pumps P8, P9, and P10 in order to execute such liquid circulation.

  When the amount of liquid developer in the developer container 272 is exhausted, the valve controller 92 holds the three-way valve V1 on the developer container and the pump controller 94 drives the second pump P2. Then, the residual developer is supplied from the residual developer tank 271 to the developer container 272. When the controller 90 rotates the motor (not shown) of the stirring member 276, the liquid developer in the developer container 272 is stirred by the stirring member 276.

  When the liquid level determination unit 93 determines that the liquid level of the liquid developer is a predetermined value, the control unit 90 causes the pump control unit 94 to stop driving the second pump P2, and the developer storage container 272. The supply of residual developer to is stopped.

  When the developer container 272 is filled with the residual developer, the solid concentration detector 273 detects the toner concentration of the liquid developer. When the solid concentration detector 273 detects that the toner concentration of the liquid developer is high, the pump controller 94 drives the pump P7 to convey the carrier liquid from the carrier tank 274 to the carrier pipe 87. The developer is supplied to the developer container 272. On the other hand, when it is detected that the toner concentration is low, the pump control unit 94 drives the pump P6 to convey the liquid developer having a high toner concentration from the toner tank 275 to the toner pipe 86 to store the developer. Supply to container 272.

  Thereafter, the solid concentration detector 273 detects the toner concentration of the liquid developer again. If the toner concentration is within an appropriate range, the pump control unit 94 drives the third pump P3 as necessary to convey the liquid developer from the developer container 272 to the third pipe 83 and to store the developer. Supply to tank 277. Further, the pump control unit 94 appropriately drives the fourth pump P4 to convey the liquid developer stored in the developer reserve tank 277 to the fourth pipe 84 and the supply nozzle 278 to be supplied to the developing device 14.

  Next, the operation of cleaning the inside of the developing device 14 and the liquid developer circulating device LY will be described with reference to FIGS.

  When a predetermined number of prints or a predetermined amount of toner is consumed, the color printer 1 enters a maintenance mode, and the developer 14 and the liquid developer circulating devices LB, LC, LM, Prompt to clean inside LY.

  First, upon receiving an input of the cleaning mode, the control unit 90 rotationally drives the developing roller 141, the supply roller 142, and the support roller 143 together with members such as the photosensitive drum 14, the intermediate transfer belt 21, and the primary transfer roller 20, The image forming unit is controlled to apply the developing bias without exposing the photosensitive drum 10 with the exposure device. When the pump control unit 94 drives the first to fourth pumps P1 to P4 and the pump P8, and the valve control unit 92 switches the three-way valve V1 to the waste tank side, the developer 14, the developer container 272, and the residual developer. The liquid developer liquid staying in the tank 271, the developer reserve tank 277, the first to fourth pipes 81 to 84 and the pipe 96 is conveyed from the second pipe 82 to the waste liquid pipe 88 and collected in the waste liquid tank 281. Is done.

  When the recovery of the liquid developer liquid into the waste liquid pipe 88 is completed, the control unit 90 holds the image forming unit such as the developing roller 141, the supply roller 142, the support roller 143, and the like, and the three-way valve V1. Holding on the waste liquid tank side, the pumps P1 to P10 are driven.

  Next, regardless of the toner concentration of the liquid developer detected by the solid content concentration detector 273, the control unit 90 drives the pump P 7 by the pump control unit 94 to transfer the carrier liquid from the carrier tank 274 to the carrier liquid. It is conveyed to the pipe 87 and supplied to the developer container 272. At the time of cleaning, this carrier liquid is used as a cleaning liquid for cleaning the container and pipe of the liquid developer circulating device.

  Thereafter, the third pump P3 is driven by the pump controller 94, and the carrier liquid in the developer container 272 is conveyed to the developer reserve tank 277 through the third pipe 83. Further, the pump control unit 94 drives the fourth pump P 4, and the carrier liquid in the developer reserve tank 277 is conveyed to the developing device 14 through the fourth pipe 84 and the supply nozzle 278.

  The carrier liquid transported to the developing device 14 is transferred from the supply roller 142 to the developing roller 141 by the rotational driving of the supply roller 142 and the developing roller 141, and from the developing cleaning blade 145 to the developer recovery unit 146 (see FIG. 3). It is conveyed to. The pump control unit 94 drives the first pump P 1, and the carrier liquid in the developer recovery unit 146 passes through the first pipe 81 and is conveyed to the residual developer tank 271.

  Further, the carrier liquid transported to the developing container 140 of the developing device 14 is transported to the residual developer tank 271 through the pipe 96 by driving the pump P8.

  Next, since the pump control unit 94 drives the second pump P2, and the valve control unit 92 holds the three-way valve V1 on the waste liquid tank side, the carrier liquid is discharged from the residual developer tank 271 to the second pipe 82 and the waste liquid. It is collected in the waste liquid tank 281 through the pipe 88.

  As described above, the valve control unit 92 holds the three-way valve V1 on the waste liquid tank side, and the pump control unit 94 performs the pump P7, the third pump P3, the fourth pump P4, the first pump P1, the second pump P2, and the pump. In a state where P8 is driven sequentially or simultaneously, each container of the developer container 272, the developer reserve tank 277, the developing device 14 and the residual developer tank 271, the third pipe 83, the fourth pipe 84, the first pipe The carrier liquid in the carrier tank 274 is transported through the pipe 81, the second pipe 82, and the pipe 96, and collected in the waste liquid tank 281. As a result, the residual developer staying in each container and each pipe is diluted with the carrier liquid, and the toner adhering to each container and each pipe is removed, and the diluted residual developer and toner are discharged into the waste liquid. It is collected in the tank 281.

  According to the first embodiment, the image forming apparatus supplies the liquid developer obtained by mixing the toner and the carrier liquid to the photosensitive drum 10 to develop the electrostatic latent image, and the developer 14 A developer storage container 272 that stores residual developer remaining after development and adjusts the toner density, a carrier tank 274 that stores a carrier liquid and is connected to the developer storage container 272, and a developer storage container that stores toner. And a toner tank 275 connected to the H.272. Further, the image forming apparatus includes first and second pipes 81 and 82, a pipe 96, first and second pumps P1, P2, and a pump P8, and a residual, which transport the residual developer from the developing device 14 to the developer container 272. Developer tank 271 (collection transport unit), third and fourth pipes 83 and 84 for transporting the liquid developer from developer storage container 272 to developing device 14, third and fourth pumps P3 and P4, and developer reserve A tank 277 (supply conveyance unit). A three-way valve V1 is provided that includes a waste liquid tank 281 that collects the carrier liquid (cleaning liquid) that has cleaned the developing device 14, and switches between transport of the liquid from the developing device 14 to the developer container 272 and transport of the liquid to the waste liquid tank 281. Was provided in the collection conveyance section.

  According to this configuration, at the time of image formation, the three-way valve V1 provided in the collection conveyance unit is switched to conveyance of the liquid to the developer storage container 272 side. The liquid developer remaining in the developing device 14 without being supplied to the photosensitive drum 10 after the image forming operation is transported to the recovery transport unit and recovered in the developer storage container 272 according to the switching of the three-way valve V1. Depending on the detection result of the toner concentration in the developer container 272, a carrier liquid is supplied from the carrier tank 274 to the developer container 272, or a liquid developer having a high toner concentration is supplied from the toner tank 275. When the toner density is adjusted, the liquid developer is transported to the supply transport unit and supplied to the developing device 14. At the time of cleaning, the three-way valve V1 is switched to transport the liquid to the waste liquid tank 281 side. The carrier liquid is transported from the carrier tank 274 to the developer container 272, and is sequentially transported to the supply transport unit, the developing device 14, and the recovery transport unit, and the waste liquid is discharged by switching the three-way valve V1 in the recovery transport unit. It is collected in the tank 281. As described above, the carrier liquid as the cleaning liquid is transported to the supply transport path, the developing device 14 and the recovery transport path, and is collected in the waste liquid tank 281, whereby the toner attached to the developing device 14 and the transport and recovery transport path. In the image formation, the liquid developer can be transported and supplied satisfactorily through the developing device and the liquid developer circulating device.

  In the above-described embodiment, the carrier liquid is used as the cleaning liquid for cleaning the container, pipe, and the like of the liquid developer circulating device. However, the present invention is not limited to this, and the volatile alcohol, the isoparaffin-based hydrocarbon solvent, and the like. The highly volatile cleaning agent may be refilled into the carrier tank 274, and transported through the developing device, each container of the liquid developer circulating device, and each pipe, and collected in the waste liquid tank. In this case, the same effect as described above can be obtained.

(Second Embodiment)
FIG. 6 is a configuration diagram of a liquid developer circulating apparatus according to another embodiment of the present invention. The cleaning liquid tank 282, which is different from the first embodiment, will be described, and the description of the same parts as the first embodiment will be omitted hereinafter.

  The cleaning liquid tank 282 is a tank for storing a highly volatile cleaning agent such as a volatile alcohol or an isoparaffin hydrocarbon solvent. In order to supply the cleaning liquid from the cleaning liquid tank 282 to the inside of the developing device 14 and the liquid developer circulating device LY, the cleaning liquid tank 282 and the toner pipe 86 are connected to the cleaning liquid pipe 89 via the three-way valve V2.

  The three-way valve V2 is provided in the middle of the toner pipe 86 that connects the toner tank 275 and the pump P6, conveys the liquid developer in the toner tank 275 to the developer container 272, and developer of the cleaning liquid in the cleaning liquid tank 282. Switching to the container 272 can be performed. Regarding this switching, the conveyance of the liquid from the toner tank 275 to the developer container 272 is hereinafter referred to as the toner tank side, and the conveyance of the liquid from the cleaning liquid tank 282 to the developer container 272 is hereinafter referred to as the cleaning liquid tank side. Called.

  At the time of image formation, the three-way valve V2 is switched to the toner tank side so that the liquid developer in the toner tank 275 can be conveyed to the developer storage container 272. At the time of cleaning, the cleaning liquid in the cleaning liquid tank 282 is transferred to the developer storage container. The three-way valve V <b> 2 is switched to the cleaning liquid tank side so that it can be conveyed to 272.

  At the time of cleaning, first, the liquid developer remaining in the developing device 14 and the liquid developer circulating devices LB, LC, LM, and LY is collected in the waste liquid tank 281. Next, the valve control unit 92 switches the three-way valve V2 to the cleaning liquid tank side, and the pump control unit 94 switches the pump P6, the third pump P3, the fourth pump P4, the first pump P1, the second pump P2, and the pump P8. In the driven state, the developer container 272, the developer reserve tank 277, the developer 14 and the residual developer tank 271, the third pipe 83, the second pipe 82, the first pipe 81, and the second pipe. The cleaning liquid in the cleaning liquid tank 282 is conveyed through the pipes 82 and 96 and collected in the waste liquid tank 281. As a result, the residual developer staying in each container and each pipe is diluted with the carrier liquid, and the toner adhering to each container and each pipe is removed, and the diluted carrier liquid and toner are discharged into the waste liquid tank 281. When the image is formed, the developer can be transported and supplied satisfactorily through the liquid developer circulating apparatus.

  In the first and second embodiments, when the pump P5 is driven to clean the inside of the circulation pipe 85 during cleaning, accurate toner concentration detection can be performed.

  The present invention can be used in an image forming apparatus provided with a liquid developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system.

These are the whole schematic sectional drawings of the color printer which concerns on embodiment of this invention. These are schematic sectional views of the color printer, excluding the part of the liquid developer circulating device according to the embodiment of the present invention. These are sectional drawings which expand and show one of the image forming parts concerning the embodiment of the present invention. These are the block diagrams of the liquid developer circulation apparatus which concerns on embodiment of this invention. These are block diagrams of the control apparatus which concerns on embodiment of this invention. These are the block diagrams of the liquid developer circulation apparatus which concerns on another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 2 Image formation part 10 Photosensitive drum (image carrier)
14 Developing Unit 81 First Pipe (Recovery Transport Unit)
82 2nd pipe (collection transport section)
83 3rd pipe (supply conveyance section)
84 4th pipe (supply conveyance section)
85 Circulating pipe 86 Toner pipe 87 Carrier pipe 88 Waste liquid pipe 89 Cleaning liquid pipe 90 Control unit 93 Valve control unit 94 Pump control unit 140 Developing container 141 Developing roller 142 Supply roller 143 Support roller 145 Developing cleaning blade 146 Developer collecting unit 271 Residual development Agent tank (collection transport section)
272 Developer container 273 Solid content detection unit 274 Carrier tank 275 Toner tank 277 Developer reserve tank (supply conveyance unit)
278 Supply nozzle 281 Waste liquid tank 282 Cleaning liquid tank LB, LC, LM, LY Liquid developer circulating device P1 to P10 Pump V1, V2 Three-way valve

Claims (1)

A developer that supplies a liquid developer, which is a mixture of toner and carrier liquid, to the image carrier and develops the electrostatic latent image, and a developer that adjusts the toner density by storing the residual developer remaining after the development of the developer A developer tank, a carrier tank that contains carrier liquid and is connected to the developer generator, a toner tank that contains toner and is connected to the developer generator, and the developer to the developer generator An image forming apparatus comprising: a recovery conveyance unit that conveys the residual developer; and a supply conveyance unit that conveys the liquid developer from the developer generation unit to the developer.
A cleaning liquid tank that stores a cleaning liquid for cleaning the developing device, and a three-way valve that switches between transport of the liquid from the toner tank to the developer generating section and transport of the liquid from the cleaning liquid tank to the developer generating section. switching to switch the a waste liquid tank for collecting the cleaning liquid to clean the developer unit provided with, and transportation of liquid into the waste liquid tank from the transport and the developing device of the liquid to the developer generator from said developing unit A portion is provided in the collection conveyance unit,
The residual developer on the developing roller in the developing unit is scraped off by a developing cleaning blade and stored in the developer generating unit,
At the time of cleaning the developing device, the three-way valve is switched to the cleaning liquid tank side, the switching unit is switched to the waste liquid tank side, and the cleaning liquid is sequentially supplied from the cleaning liquid tank to the developer generating unit, wherein the supply conveyor section, the developing unit and the image forming apparatus characterized by being recovered in the waste liquid tank is fed transportable to said collecting conveyor unit.

Images