JP2009139913A - Liquid developer collecting system and image forming apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid developer collecting system that reduces the consumption amount of new carrier and efficiently performs concentration control by effectively using carrier-rich liquid developer collected from a photosensitive body by a cleaner in a simplified structure, and to provide an image forming apparatus including the liquid developer collecting system. <P>SOLUTION: The liquid developer collecting system includes the photosensitive body, a collection section which collects the liquid developer from the photosensitive body, a storage section which stores the liquid developer collected by the collection section, a concentration control section, and a first feed section which feeds the liquid developer from the storage section to the concentration control section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a plurality of developing devices for developing electrostatic latent images formed on each of the plurality of photosensitive members using a liquid developer using a non-volatile solvent as a carrier, and the plurality of developing devices. A transfer body that sequentially transfers and superimposes the developed toner images at transfer sections corresponding to the respective photoreceptors, and a liquid developer collection system that reuses the liquid developer collected from the photoreceptor after transfer. And an image forming apparatus including the same.

  Various wet image forming apparatuses that develop a latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent and visualize the electrostatic latent image have been proposed. The liquid developer used in this wet image forming apparatus is obtained by suspending solids (toner particles) in an electrically insulating organic solvent (carrier) made of silicon oil, mineral oil, edible oil, etc. The toner particles have a very fine particle diameter of about 1 μm. By using such fine toner particles, the wet image forming apparatus can achieve higher image quality than a dry image forming apparatus using powder toner particles having a particle diameter of about 7 μm.

  In such an image forming apparatus using a liquid developer, the electrostatic latent image on the photosensitive member is developed with the liquid developer by the developing device, the toner image on the photosensitive member is transferred to the transfer member, and the photosensitive material after transfer is performed. It has been proposed that a liquid developer having a large amount of carrier is recovered and reused by a cleaner that abuts on the body.

The liquid developer containing a large amount of carrier is sent to the density adjusting means using a pump or the like. The liquid developer recovered by the developing device is also transported to the density adjusting means, supplied with high-concentration liquid toner, mixed with the diluted recovered liquid developer, and adjusted to the target value solid content concentration. The liquid developer adjusted to the target solid content concentration is sent again to the developing device and reused.
JP 2002-6737 A

  However, when reusing the liquid developer recovered by the cleaner from the photoconductor having a large amount of carrier, it is necessary to adjust the target density together with the recovered liquid developer recovered from the developing device by the density adjusting device. In the case of a color image forming apparatus, in order to prevent color mixing, a concentration adjustment device for the collected liquid developer is installed for each color. Due to the demand for miniaturization of the image forming apparatus, the capacity of the density adjusting device must be reduced.

  In order to bring the recovered liquid developer having a large amount of carrier to the target density with a small-capacity density adjusting device, new toner with a high density is supplied from the toner tank to the density adjusting device. If the density of the new toner is about 35% and the target density is 20%, and the total solid concentration of the collected liquid developer is 17%, the density adjustment device can adjust the target density. A new toner having a density of 35% has to be supplied in a predetermined amount, and there is a problem that the density cannot be adjusted efficiently if the density adjusting device does not have a free space.

  The present invention solves the above-mentioned problems and is a liquid that can efficiently adjust the concentration by reducing the consumption of a new carrier by effectively using a liquid developer with a large amount of carrier that is recovered from the photoreceptor by a cleaner with a simple configuration. It is an object of the present invention to provide a developer recovery system and an image forming apparatus including the same.

  In order to solve the above problems, the liquid developer recovery system of the present invention includes a photoconductor, a recovery unit that recovers the liquid developer from the photoconductor, and a storage unit that stores the liquid developer in the recovery unit. A density adjusting unit; and a first conveying unit configured to convey the liquid developer from the storage unit to the density adjusting unit. The storage unit functions as a buffer tank for the carrier liquid for reusing the recovered liquid developer from the photoconductor having a large amount of carrier, and can reduce the consumption of new carrier, and the density adjusting means for reuse. The density adjustment by can be carried out efficiently.

  The liquid developer recovery system of the present invention includes a waste tank and a second transport unit that transports the liquid developer from the storage unit to the waste tank. It is possible to quickly select reuse or disposal in response to changes in the amount of liquid developer to be collected and the solid content concentration.

  Also, the liquid developer recovery system of the present invention includes a plurality of photoconductors, a recovery unit that recovers liquid developer disposed on at least one of the plurality of photoconductors, and a recovery unit that recovers the liquid developer. One or more storage units for storing the liquid developer, a density adjusting unit, and a transport unit for transporting the liquid developer from the storage unit to the density adjusting unit. The storage unit functions as a buffer tank for the carrier liquid for reusing the recovered liquid developer from the photoconductor having a large amount of carrier, and can reduce the consumption of new carrier, and the density adjusting means for reuse. The density adjustment by can be carried out efficiently.

  Further, the liquid developer recovery system of the present invention has a transfer member to which an image formed by the plurality of photoconductors is transferred, and the storage section is a first transfer member of the plurality of photoconductors. And a storage unit for storing the liquid developer recovered by the photoconductor that forms an image to be transferred. Occurrence of color mixing due to reuse of the liquid developer with a large amount of recovered carrier can be avoided.

  In the liquid developer recovery system of the present invention, the storage unit has a storage unit for the liquid developer recovered by each of the plurality of photoconductors. The liquid developer having a large amount of carrier recovered from all the photoreceptors can be reused efficiently, and the consumption of new carriers can be reduced.

  The liquid developer recovery system of the present invention is disposed in the storage unit liquid level sensor disposed in the storage unit, the concentration adjustment unit liquid level sensor disposed in the concentration adjustment unit, and the concentration adjustment unit. A concentration unit, a distribution unit that distributes the first conveyance unit and the second conveyance unit, and the distribution unit is at least one of the storage unit liquid level sensor, the concentration adjustment unit liquid level sensor, and the concentration sensor. And a control unit that performs control based on the data. Efficient reuse can be achieved in response to changes in the amount of liquid developer collected and the solid content concentration.

  In the liquid developer recovery system of the present invention, the distribution unit is a switching valve. It is possible to quickly select reuse or disposal in response to changes in the amount of liquid developer to be collected and the solid content concentration.

In the liquid developer recovery system of the present invention, the distribution unit is a drive pump disposed in the first transport unit and the second transport unit. It is possible to quickly select reuse or disposal in response to changes in the amount of liquid developer to be collected and the solid content concentration.

  The image forming apparatus of the present invention includes a plurality of photosensitive members on which an electrostatic latent image is formed, a developing unit that develops the electrostatic latent image with a liquid developer to form an image, and an image of the photosensitive member. A transfer member to which the liquid developer is transferred, a recovery unit that recovers the liquid developer from the photoconductor, one or more storage units that store the liquid developer recovered by the recovery unit, a density adjustment unit, and the storage And a first conveyance unit that conveys the liquid developer from the unit to the density adjustment unit. An image forming apparatus capable of reusing the liquid developer recovered from the photoreceptor with a simple configuration can be provided.

  The image forming apparatus of the present invention further includes a second transport unit that transports the liquid developer from the storage unit to the waste tank. It is possible to quickly select reuse or disposal in response to changes in the amount of liquid developer to be collected and the solid content concentration.

  In the image forming apparatus according to the aspect of the invention, the storage unit may be a storage unit that stores the liquid developer recovered by the photoconductor that forms an image transferred to the transfer member in the first of the plurality of photoconductors. is there. Occurrence of color mixing due to reuse of the liquid developer with a large amount of recovered carrier can be avoided.

  In the image forming apparatus of the present invention, the storage unit has a storage unit for the liquid developer collected by each of the plurality of photoconductors. The liquid developer having a large amount of carrier recovered from all the photoreceptors can be reused efficiently, and the consumption of new carriers can be reduced.

  Further, the image forming apparatus of the present invention includes a storage unit liquid level sensor disposed in the storage unit, a concentration adjustment unit liquid level sensor disposed in the concentration adjustment unit, and a concentration sensor disposed in the concentration adjustment unit. A distribution unit that distributes the first conveyance unit and the second conveyance unit, and the distribution unit based on at least one data of the storage unit liquid level sensor, the concentration adjustment unit liquid level sensor, and the concentration sensor A control unit for controlling. Efficient reuse can be achieved in response to changes in the amount of liquid developer collected and the solid content concentration.

  In the image forming apparatus of the present invention, the distribution unit is a switching valve. It is possible to quickly select reuse or disposal in response to changes in the amount of liquid developer to be collected and the solid content concentration.

  In the image forming apparatus of the present invention, the distribution unit is a drive pump disposed in the first conveyance unit and the second conveyance unit. It is possible to quickly select reuse or disposal in response to changes in the amount of liquid developer to be collected and the solid content concentration.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating main components constituting an image forming apparatus including a liquid developer recovery system according to the first embodiment of the present invention, and FIG. 2 is an image forming unit according to the first embodiment of the present invention. FIG. 2 is a partially enlarged view showing main components of a developing unit and an intermediate transfer member and a liquid developer recovery system. In FIG. 1, for each color composed of yellow (Y), magenta (M), cyan (C), and black (K), the same component is given Y, M, C, and K representing each color. The same number is used. Among them, FIG. 2 shows a configuration of a yellow (Y) image forming unit, a developing unit, an intermediate transfer member, and a liquid developer collecting system.

  As shown in FIG. 1, an image forming apparatus 1 according to this embodiment includes a photosensitive member that is a latent image carrier of yellow (Y), magenta (M), cyan (C), and black (K) arranged in tandem. 2Y, 2M, 2C, 2K. Here, in each of the photoreceptors 10Y, 10M, 10C, and 10K, 10Y represents a yellow photoreceptor, 10M represents a magenta photoreceptor, 10C represents a cyan photoreceptor, and 10K represents a black photoreceptor. In the embodiment shown in FIG. 1, all of them are constituted by a photosensitive drum. Each of the photoconductors 10Y, 10M, 10C, and 10K can also be configured as an endless belt.

  As shown in FIG. 2, the image forming unit includes a corona charger 11Y, an exposure unit 12Y, a developing roller 20Y, a photoreceptor squeeze roller 13Y, and a photoreceptor cleaning along the rotation direction (movement direction) of the outer periphery of the photoreceptor 10Y. A blade 15Y is arranged. The photoconductor squeeze roller 13Y is disposed between the developing roller 20Y and the primary transfer portion 50Y so as to face the photoconductor 10Y. The photosensitive member squeeze roller 13Y is provided with a squeeze roller cleaning blade 14Y that is in pressure-sliding contact with the surface thereof.

  The developing roller cleaning blade 21Y contacts the outer periphery of the developing roller 20Y on the downstream side of the developing nip, and the developer supply roller 32Y using an anilox roller contacts the upstream side of the developing nip of the developing roller 20Y. A regulating blade 33Y that regulates the developer supply amount abuts on the developer supply roller 32Y. A corona charger 22Y for charging the toner is disposed between the developing nip and the developer supply roller 32Y. A developer supply roller 32Y is disposed in a developer container (toner reservoir) 31Y in which the liquid developer is accommodated. A primary transfer roller (not shown) of the primary transfer portion 50Y is disposed at a position facing the photoreceptor 10Y with the intermediate transfer body 40 interposed therebetween. An intermediate transfer member cleaning blade 55 is disposed on the intermediate transfer member 40.

  In the liquid developer accommodated in the developer container 31Y, as the toner, for example, particles having an average particle diameter of 1 μm in which a colorant such as a known pigment is dispersed in a known thermoplastic resin used for the toner are used. Can be used. On the other hand, as the liquid carrier, in the case of a low-viscosity low-concentration liquid developer, for example, an insulating liquid carrier of Isopar (trademark: Exxon) can be used. In the case of a liquid developer having a high viscosity and high concentration as a liquid carrier, for example, an organic solvent, a silicone oil having a flash point of 210 ° C. or higher, mineral oil, boiling point, such as phenylmethylsiloxane, dimethylpolysiloxane and polydimethylcyclosiloxane Use an insulating liquid carrier such as aliphatic saturated hydrocarbons such as liquid paraffin with a relatively low viscosity having a viscosity of 3 mPa · s at 170 ° C. or higher and normal viscosity, vegetable oil, edible oil, higher fatty acid ester, etc. Can do. The liquid developers 23Y, 23M, 23C, and 23K are obtained by adding toner particles to a liquid carrier together with a dispersant to a toner solid content concentration of about 20%.

  In the image forming unit and the developing unit, the photoconductor 10Y is uniformly charged by the corona charger 11Y, and the input image signal is input by the exposure unit 12Y having an optical system such as a semiconductor laser, a polygon mirror, and an F-θ lens. Then, a modulated laser beam is irradiated to form an electrostatic latent image on the charged photoconductor 10Y.

  Then, the amount of developer supplied is regulated by the regulating blade 33Y from the developer container 31Y storing the liquid developer of each color (here, yellow), and the liquid developer is supplied from the developer supply roller 32Y to the developing roller 20Y. The electrostatic latent image formed on the body 10Y is developed. A photoreceptor squeeze roller 13Y comes into contact with the photoreceptor 10Y on which the electrostatic latent image has been developed by the developing roller 20Y, and excess carriers are copied. A squeeze roller cleaning blade 14Y contacts the photoconductor squeeze roller 13Y, and the liquid developer copied from the photoconductor 10Y is collected. The photoreceptor squeeze roller 13Y is a conductive elastic roller in which an elastic member such as conductive urethane rubber and a fluororesin surface layer are arranged on the surface of a metal core.

  The intermediate transfer member 40 is an endless belt member, is wound around and stretched between the driving roller 41 and the driven roller 42, and the photosensitive members 10Y, 10M, 10C, and 50C are primary transfer units 50Y, 50M, 50C, and 50K. It is rotationally driven by the drive roller 41 while abutting 10K. The primary transfer portions 50Y, 50M, 50C, and 50K are arranged so that a primary transfer roller (not shown) faces the photoconductors 10Y, 10M, 10C, and 10K with the intermediate transfer body 40 interposed therebetween. Using the contact position with 10K as a transfer position, a primary transfer bias is applied to each color toner image on the developed photoconductors 10Y, 10M, 10C, and 10K, and the images are sequentially transferred onto the intermediate transfer body 40 and transferred to full color. The toner image is formed.

  Of the plurality of photoconductors 10Y, 10M, 10C, and 10K, at least the photoconductor 10Y that is first transferred to the intermediate transfer body 40 is in contact with the photoconductor cleaning blade 15Y on the photoconductor 10Y after the primary transfer to perform primary transfer. The liquid developer remaining in the carrier is scraped off and collected, temporarily stored in the yellow buffer tank 70Y, and conveyed from the yellow buffer tank 70Y to the yellow density adjusting tank 82Y. In the first embodiment, a buffer tank is provided only in the photosensitive member 10Y that is first transferred to the transfer member, and the liquid developer collected from the uppermost photosensitive member is transported to the density adjustment tank and reused. This is because color mixing does not occur. The liquid developer recovered from each photoconductor may be reused by providing it on all photoconductors in the buffer tank.

  In the secondary transfer unit 60, the secondary transfer roller 61 is disposed to face the belt driving roller 41 with the intermediate transfer body 40 interposed therebetween. In the secondary transfer unit 60, the full-color toner image or the single-color toner image formed by superimposing colors on the intermediate transfer body 40 reaches the transfer position of the secondary transfer unit 60 in the sheet material conveyance path. Then, a sheet material such as paper, film or cloth is conveyed and supplied, and a secondary transfer bias is applied to secondary transfer a single color toner image or a full color toner image onto the sheet material. A fixing unit (not shown) is disposed in front of the sheet material conveyance path, and a single color toner image or a full color toner image transferred onto the sheet material is fused to a recording medium (sheet material) such as paper and fixed. Image formation on the final sheet material is completed.

  The intermediate transfer member cleaning blade 55 comes into contact with the intermediate transfer member 40 after the secondary transfer, and the remaining liquid developer is collected and conveyed to the waste tank 90.

  The liquid developer collected from the photoreceptor squeeze roller 13Y disposed between the development position of the photoreceptor 10Y by the developing roller 20Y and the primary transfer unit 50Y is collected for each color, conveyed to the collection unit 36Y, and reused.

  The developer container 31Y for storing the liquid developer is partitioned into a storage part 35Y and a recovery part 36Y by a partition wall 34Y. A developer supply roller 32Y that supplies a liquid developer to the developing roller 20Y is disposed in the storage unit 35Y. A developing roller cleaning blade 21Y is in contact with the outer periphery of the developing roller 20Y on the downstream side of the developing nip with the photoreceptor 10Y, and the liquid developer is scraped and collected from the developed developing roller 20Y and conveyed to the collecting unit 36Y.

  The liquid developer with a large amount of carrier collected by the photoconductor cleaning blade 15Y that comes into contact with the photoconductor 10Y after the primary transfer is conveyed to the yellow buffer tank 70Y and is collected in the yellow buffer tank 70Y. The agent is transported to the yellow concentration adjusting tank 82Y via a pump as needed and reused.

  The first embodiment of the recovery system for the liquid developer having a large amount of carriers recovered from the photosensitive member cleaning blade 15Y from above the photosensitive member shown in FIGS. 1 and 2 is the yellow transferred to the intermediate transfer member 40 first. The buffer tank 70Y is disposed only on the photoconductor 10Y. In the present embodiment, only the liquid developer recovered from the yellow photoreceptor 10Y positioned at the most upstream is transported to the buffer tank 70Y and reused because no color mixing occurs. The liquid developer having a large amount of carrier collected from the yellow photoreceptor 10Y by the photoreceptor cleaning blade 15Y is conveyed and stored in the yellow buffer tank 70Y. The liquid developer collected by the photoconductor cleaning blades 15M, 15C, and 15K from the other photoconductors 10M, 10C, and 10K is conveyed to the waste tank 90.

  In order to reuse the yellow liquid developer, a yellow toner tank 81Y, a yellow density adjustment tank 82Y, and a common carrier tank 80 for storing a new carrier are provided. The common carrier tank 80 and density adjustment tanks 82Y, 82M, 82C, and 82K arranged for each color communicate with each other through a conveyance line via a pump.

  In the yellow density adjustment tank 82Y, the collected liquid developer from the collecting section 36Y of the developing section, the collected liquid developer having a large amount of carrier from the yellow buffer tank 70Y, and a new toner having a density of about 35% from the yellow toner tank 81Y. A new carrier is supplied from the common carrier tank 80 through a conveyance line via a pump. Further, the yellow density adjustment tank 82Y communicates with the storage portion 35Y of the developer container 31Y through a transport line via a pump, and uses the recovered liquid developer.

  In the yellow concentration adjustment tank 82Y, a concentration sensor for measuring the concentration, a liquid level sensor for measuring the liquid level, and a stirring means are arranged. The concentration sensor is a light reflection type or light transmission type, and the liquid level sensor is a plurality of binary Hall elements arranged vertically in the concentration adjustment tank, and the buoyancy body is a magnetic force generator. Is fixed. The concentration sensor and liquid level sensor in the concentration adjustment tank 82Y will be described later.

  The liquid developer recovered from the developing roller 20Y after development by the developing roller cleaning blade 21Y and transported to the collecting unit 36Y has a solid content concentration that changes according to the image data. That is, when the image data is solid, many solid particles move to the photoconductor and are consumed, so that the solid content concentration of the recovered liquid developer becomes low. Further, when the image data is halftone, the solid content concentration of the liquid developer collected with a small amount of solid particles moving to the photosensitive member does not change much.

  The liquid developer that is abutted on the photoreceptor 10Y after the development and before the primary transfer and scrapes the remaining liquid developer from the photoreceptor squeeze roller 13Y by the squeeze roller cleaning blade 14Y and transported to the collection unit 36Y is stored in the carrier. The proportion is large and the solid concentration is low.

  The temporarily stored liquid developer collected by the photoconductor cleaning blade 15Y that contacts the photoconductor 10Y after the primary transfer and once transported to the yellow buffer tank 70Y has a high carrier ratio and a low solid content concentration.

  Since the amount of the liquid developer supplied to the storage unit 35Y of the developer container 31Y is set to be slightly larger than the liquid developer consumption accompanying the development, it overflows over the partition wall 34Y to the recovery unit 36Y. . Since the liquid developer overflowing from the storage unit 35Y is adjusted to the target density, there is no density change.

  Of the recovered liquid developer flowing into the recovery portion 36Y of the developer container 31Y, the amount of liquid developer recovered by the developing roller cleaning blade 21Y from the developed roller 20Y after development is the largest, and the solid content concentration The biggest fluctuation is. Therefore, the solid content concentration of the liquid developer recovered from the developing roller 20Y affects the solid content concentration of the entire recovered liquid developer.

  The density adjustment tank 82Y for adjusting the collected liquid developer to the target density and reusing it is provided for each color in order to prevent color mixing, so the capacity must be small. For example, in order to set the solid content concentration of 17% of the collected liquid developer in the concentration adjustment tank 82Y to a target solid content concentration of 20%, new toner having a solid content concentration of 35% in the toner tank 81Y is supplied and stirred. In this case, the density adjustment tank 82Y needs a remaining volume for adding new toner.

  However, when the solid content concentration of the liquid developer conveyed from the recovery unit 36Y of the developer container 31Y is lower than a predetermined value, a large amount of new toner is supplied to the concentration adjustment tank 82Y in order to adjust the target concentration. In the state where the capacity of the concentration adjustment tank 82Y is limited, there arises a problem that it is difficult to efficiently adjust the solid content concentration.

  In such a state, when the recovered liquid developer having a large amount of carrier recovered from the photosensitive member 10Y by the photosensitive member cleaning blade 15Y is directly conveyed to the concentration adjusting tank 82Y, the solid concentration becomes lower and the concentration adjustment becomes difficult. Become. Therefore, in the liquid developer recovery system according to the first embodiment of the present invention, the liquid developer with a large amount of carrier recovered from the most upstream yellow photoconductor 10Y without occurrence of color mixture is temporarily stored in the yellow buffer tank 70Y. When it is necessary to supply the carrier for the concentration adjustment of the collected liquid developer from the collecting unit 36Y in the yellow concentration adjusting tank 82Y, instead of supplying a new carrier from the carrier tank 80, yellow is stored. A liquid developer containing a large amount of carrier is supplied from the buffer tank 70Y for reuse.

  For this reason, a liquid level sensor is disposed in the yellow buffer tank 70Y, and it is determined that the carrier needs to be supplied based on the concentration sensor disposed in the yellow concentration adjustment tank 82Y and the measurement data of the liquid level sensor. Then, the liquid level sensor of the yellow buffer tank 70Y determines the storage amount, and the control means drives the pump to supply a predetermined amount of recovered liquid developer for the carrier to the yellow concentration adjustment tank 82Y instead of the new carrier. To do.

  By temporarily storing the collected liquid developer with a large amount of carrier and reusing it instead of a new carrier, the consumption of the new carrier can be reduced, and density adjustment by the density adjustment means for reuse is possible. Can be implemented efficiently.

  FIG. 3 is a diagram showing main components constituting an image forming apparatus including a liquid developer recovery system according to the second embodiment of the present invention, and FIG. 4 is an image forming unit according to the second embodiment of the present invention. FIG. 2 is a partially enlarged view showing main components of a developing unit and an intermediate transfer member and a liquid developer recovery system. In FIG. 3, for each color composed of yellow (Y), magenta (M), cyan (C), and black (K), Y, M, C, and K representing each color are given to the same component. The same number is used. Among them, FIG. 4 shows a configuration of a yellow (Y) image forming unit, a developing unit, an intermediate transfer member, and a liquid developer collecting system.

  The image forming apparatus provided with the liquid developer recovery system of the second embodiment has a large amount of carrier recovered from the photoreceptors 10Y, 10M, 10C, and 10K by the photoreceptor cleaning blades 15Y, 15M, 15C, and 15K. Buffer tanks 70Y, 70M, 70C, and 70K that temporarily store the liquid developer are provided. Furthermore, the buffer tanks 70Y, 70M, 70C, 70K arranged for each color communicate with the distributing means 84Y, 84M, 84C, 84K. The distribution means 84Y, 84M, 84C, 84K distribute the recovered liquid developer having a large amount of recovered carrier to the concentration adjusting tanks 82Y, 82M, 82C, 82K and the waste tank 90. The distribution means 84Y, 84M, 84C, and 84K in this embodiment include a first position at which the supply of the collected liquid developer from the buffer tanks 70Y, 70M, 70C, and 70K is stopped, and the collected liquid developer in the concentration adjustment tank 82Y. , 82M, 82C, 82K, and a third position where the recovered liquid developer is supplied to the waste tank 90, and an electromagnetic switching valve that can be switched to the first position. Switching to any one of the positions is controlled.

  Liquid level sensors are disposed in the buffer tanks 70Y, 70M, 70C, and 70K, and liquid level sensors and concentration sensors are disposed in the concentration adjustment tanks 82Y, 82M, 82C, and 82K. When it is determined that the carrier needs to be supplied at the time of concentration adjustment when the measured values of the liquid level sensors in the concentration adjustment tanks 82Y, 82M, 82C, and 82K are equal to or less than a predetermined value, the control unit determines that the distribution unit 84Y, 84M, 84C, The pump is driven to switch the 84K electromagnetic switching valve from the first position to the second position, and a predetermined amount of recovered liquid developer corresponding to the carrier is supplied to the concentration adjustment tanks 82Y, 82M, 82C, and 82K.

  When the liquid level sensors arranged in the concentration adjustment tanks 82Y, 82M, 82C, and 82K are equal to or higher than the predetermined liquid level, it is determined that the supply of the carrier is not necessary for concentration adjustment, and the control unit switches the distribution unit to the third position. The recovered liquid developer having a large amount of carrier in the buffer tanks 70Y, 70M, 70C, and 70K is transported to the waste tank 90 by driving the pump.

  Concentration adjustment tank 82Y is provided by means for conveying the recovered liquid developer having a large amount of carrier in buffer tanks 70Y, 70M, 70C, and 70K to concentration adjustment tanks 82Y, 82M, 82C, and 82K and waste tank 90 by distribution means. , 82M, 82C, and 82K, the density can be adjusted efficiently.

  FIG. 5 is a diagram showing main components constituting an image forming apparatus provided with a liquid developer recovery system according to the third embodiment of the present invention, and FIG. 6 is an image forming section of the second embodiment of the present invention. FIG. 2 is a partially enlarged view showing main components of a developing unit and an intermediate transfer member and a liquid developer recovery system. In FIG. 5, for each color composed of yellow (Y), magenta (M), cyan (C), and black (K), the same component is given Y, M, C, and K representing each color. The same number is used. Among them, FIG. 6 shows a configuration of a yellow (Y) image forming unit, a developing unit, an intermediate transfer member, and a liquid developer collecting system.

  The image forming apparatus provided with the liquid developer recovery system of the third embodiment has a large amount of carrier recovered from the photoreceptors 10Y, 10M, 10C, and 10K by the photoreceptor cleaning blades 15Y, 15M, 15C, and 15K. Buffer tanks 70Y, 70M, 70C, and 70K that temporarily store the liquid developer are provided. Further, the buffer tanks 70Y, 70M, 70C, and 70K arranged for the respective colors communicate with the concentration adjusting tanks 82Y, 82M, 82C, and 82K and the waste tank 90 through pumps that are separately driven. In the third embodiment, as a distribution unit, a drive pump that conveys the recovered liquid developer having a large amount of carrier from the buffer tanks 70Y, 70M, 70C, and 70K to the concentration adjustment tanks 82Y, 82M, 82C, and 82K, and the buffer tank 70Y , 70M, 70C, and 70K, the drive pumps transported to the waste tank 90 are controlled by the control means and driven. Since other configurations are the same as those of the second embodiment, the description thereof is omitted.

  The density and liquid level of the liquid developer are measured by the density sensor and the liquid level sensor arranged in the density adjustment tank 82Y. First, the liquid amount measuring device 110Y that is a liquid level sensor will be described. As shown in FIG. 7, the liquid amount measuring device 110Y includes a float support member 111Y, a first Hall element 113Y as an example of a proportional output Hall element, a second Hall element 114Y, a third Hall element 115Y, and an example of a floating member. As a float 116Y, a first magnetic field generator 117Y, and a second magnetic field generator 118Y.

  The float support member 111Y is a member that movably supports the float 116Y from above the liquid level in the yellow concentration adjustment tank 82Y to a substantially bottom part below the liquid level, and includes a first hall element 113Y, a second hall element 114Y, and a third hall element. Hall elements 115Y are provided in order from the bottom at a predetermined distance.

  The first Hall element 113Y, the second Hall element 114Y, and the third Hall element 115Y are proportional output Hall elements whose output voltage changes with respect to the magnetic flux density. In the present embodiment, the distance between the Hall elements is 30 mm.

  The float 116Y floats on the liquid surface and is movable relative to the float support member 111Y depending on the liquid surface position. The float 116Y includes a first magnetic field generator 117Y below and a second magnetic field generator 118Y above a predetermined distance. . The first magnetic field generator 117Y and the second magnetic field generator 118Y are provided so as to move facing the hall elements 113Y, 114Y, 115Y as the float 116Y moves. The first magnetic field generator 117Y and the second magnetic field generator 118Y are arranged so that the N pole and the S pole are reversed. In the present embodiment, magnetic field generators 117Y and 118Y having a diameter of 5 mm, a length of 6 mm, and 4000 gauss are arranged with a distance of 20 mm. In the second and third embodiments, the liquid level sensors arranged in the buffer tanks 70Y, 70M, 70C, and 70K have the same configuration as the liquid level sensors arranged in the concentration adjustment tanks 82Y, 82M, 82C, and 82K. .

  The concentration measuring device 120Y which is a concentration sensor includes a stirring propeller shaft 121Y, a transparent propeller 122Y as an example of a moving member, a stirring propeller 123Y as an example of a stirring member, and a concentration measuring unit 130Y. The stirring propeller shaft 121Y is a member that is provided with a transparent propeller 122Y and a stirring propeller 123Y coaxially and is rotated by a motor.

  A density detection method using the density measurement unit 130Y and the transparent propeller 122Y will be described. As shown in FIG. 8, the transparent propeller 122Y is supported by the stirring propeller shaft 121Y and is made of a flat plate member such as a rotatable rectangle, and the gap 130cY between the first member 130aY and the second member 130bY of the concentration measuring unit 130Y. It has a structure that passes through the inside intermittently. The first member 130aY or the second member 130bY can move, and the distance 130cY can be changed. Further, the distance of the gap 130cY can be varied depending on the color of the liquid developer.

  In the transmission type concentration measuring unit 130Y as shown in FIGS. 9A and 9B, a light emitting LED 131Y as an example of a concentration measuring member and a concentration measuring light receiving element 132Y are arranged to face each other with the gap 130cY interposed therebetween. Yes. Further, a light receiving element 133Y for measuring light emission intensity is arranged on the light emitting LED 131Y side.

  As shown in FIG. 10, the light emitting LED 131Y, the density measuring light receiving element 132Y, and the light emitting intensity measuring light receiving element 133Y are each connected to the CPU 134Y. The light emitting LED 131Y is connected to the CPU 134Y via the amplifier 135Y, the density measuring light receiving element 132Y is connected to the CPU 134Y via the first A / D converter 136Y, and the light emitting intensity measuring light receiving element 133Y is connected to the second A / D converter 137. To the CPU 134Y.

  Further, in the reflection type density measuring unit 130Y as shown in FIG. 11, a light emitting LED 131Y, a density measuring light receiving element 132Y, and a light emitting intensity measuring light receiving element 133Y are arranged on one side with respect to the gap 130cY. A reflective film 140Y is disposed on the other side of the gap 130cY.

  With such a structure, the light emitted from the light emitting LED 131Y passes through the liquid developer on the light emitting LED 131Y side, the transparent propeller 122Y, and the liquid developer on the reflective film 140Y side from the transparent propeller 122Y, and is reflected by the reflective film 140Y. An optical path that passes through the liquid developer on the reflective film 140Y side, the transparent propeller 122Y, and the liquid developer on the density measuring light receiving element 132Y side from the transparent propeller 122Y and is received by the density measuring light receiving element 132Y, and the transparent propeller 122Y And a light path that passes through the liquid developer on the light emitting LED 131Y side and is received by the light receiving element 133Y for light emission intensity measurement.

  The light emitting LED 131Y, the density measuring light receiving element 132Y, and the light emitting intensity measuring light receiving element 133Y are each connected to the CPU 134Y. The light emitting LED 131Y is connected to the CPU 134Y via the amplifier 135Y, the density measuring light receiving element 132Y is connected to the CPU 134Y via the first A / D converter 136Y, and the light emitting intensity measuring light receiving element 133Y is connected to the second A / D converter 137Y. To the CPU 134Y.

  FIG. 12 shows an example of a sequence of a flowchart of the liquid developer recovery system of the present invention. In this free chart sequence, first, in step (1), the concentration and liquid level are measured by the concentration measuring device 120Y and the liquid amount measuring device 110Y arranged in the concentration adjusting tank 82Y. In step (2), it is determined whether or not the carrier needs to be supplied to the concentration adjustment tank 82Y. When it determines with YES at the process of (2), it transfers to the process of (3). In step (3), it is determined whether or not there is a recovered liquid developer having a predetermined amount of carrier based on the data of the liquid level sensor arranged in the buffer tank 70Y. If it is determined YES in step (3), the process proceeds to step (4). If it is determined NO in step (3), the process proceeds to step (5). In the step (4), the recovered liquid developer having a large amount of carrier in the buffer tank 70Y is conveyed to the predetermined concentration adjusting tank 82Y via the distributing means 84Y. In step (5), the pump is driven from the common carrier tank 80, and a predetermined amount of new carrier is conveyed to the concentration adjusting tank 82Y.

  FIG. 13 shows an example of a sequence of a flowchart of the liquid developer recovery system of the third embodiment when the recovered liquid developer in the buffer tank 70Y is transported to the waste tank 90. First, in step (6), it is determined whether or not the liquid level in the concentration adjustment tank 82Y is greater than or equal to a predetermined value (118 mm) by the liquid amount measuring device 110Y disposed in the concentration adjustment tank 82Y. If it is determined YES in step (6), the process proceeds to step (7). In the step (7), the collected liquid developer in the buffer tank 70Y is transported to the waste tank 90 by driving the pump for 30 seconds at a liquid feed speed of 160 ml / min. After 30 seconds, the process returns to step (6), and it is determined whether or not the liquid level in the concentration adjustment tank 82Y is equal to or greater than a predetermined value (118 mm) by the liquid amount measuring device 110Y disposed in the concentration adjustment tank 82Y.

  In the flowchart shown in FIG. 13, in the sequence of the liquid developer recovery system of the second embodiment, first, in the step (6), the liquid amount measuring device 110Y disposed in the concentration adjustment tank 82Y uses the concentration adjustment tank 82Y. It is determined whether or not the liquid level is a predetermined value (115 mm) or more. If it is determined YES in step (6), the process proceeds to step (7). In the step (7), the recovered liquid developer in the buffer tank 70Y is transferred to the waste tank 90 for 1 minute by switching the electromagnetic valve of the distribution means 84Y. After 1 minute, the process returns to step (6), and the liquid level measuring device 110Y disposed in the concentration adjustment tank 82Y determines whether or not the liquid level in the concentration adjustment tank 82Y is equal to or greater than a predetermined value (115 mm).

  In the flowchart shown in FIG. 14, in the sequence of the liquid developer recovery system of the third embodiment, first, in the step (8), the liquid amount measuring device 110Y arranged in the concentration adjustment tank 82Y is used to adjust the concentration adjustment tank 82Y. It is determined whether the liquid level is equal to or higher than a predetermined value. If it is determined YES in step (8), the process proceeds to step (9). In step (9), it is determined whether or not the detection result by the full detection sensor arranged in the buffer tank 70Y is full. If the buffer tank 70Y is full in the process (9) (YES), the process proceeds to the process (10). In step (10), the liquid developer collected in the buffer tank 70Y is fed to the waste tank 90 by driving the pump for 5 seconds. After 5 seconds, the process returns to step (8) to determine whether or not the liquid level in the concentration adjustment tank 82Y is equal to or higher than a predetermined value by the liquid amount measurement device 110Y disposed in the concentration adjustment tank 82Y. When the buffer tank 70Y is not full in the process (9) (NO), the process proceeds to the process (11). In the step (11), the drive of the pump that sends liquid to the waste tank 90 is stopped.

  As described above, the liquid developer collection system of the present invention can reduce the consumption of new carriers, can adjust the concentration of the collected liquid developer efficiently with a simple configuration, and can reduce the arrangement space of the apparatus. Can contribute to downsizing of the image forming apparatus.

It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention. It is a figure which shows embodiment of this invention.

Explanation of symbols

  10Y, M, C, K: Photoconductor, 11Y, M, C, K: Corona charger, 12Y, M, C, K: Exposure unit, 13Y, M, C, K: Photoconductor squeeze roller, 14Y, M , C, K: Squeeze roller cleaning blade, 15Y, M, C, K: Photoconductor cleaning blade, 20Y, M, C, K: Development roller, 21Y, M, C, K: Development roller cleaning blade, 22Y, M C, K: Corona charger for toner charging, 31Y, M, C, K: Developer container, 32Y, M, C, K: Developer supply roller, 33Y, M, C, K: Regulating blade, 34Y, M, C, K: partition walls, 35Y, M, C, K: storage section, 36Y, M, C, K: collection section, 40: intermediate transfer belt, 41: drive roller, 42: driven roller, 55: intermediate transfer Body cleaning blade, 60: 2 Transfer section, 61: secondary transfer roller, 70Y, M, C, K: buffer tank, 80: common carrier tank, 81Y, M, C, K: toner tank, 82Y, M, C, K: density adjustment tank, 84Y, M, C, K: Distributing means, 90: Waste tank, 110Y, M, C, K: Liquid quantity measuring device, 120Y, M, C, K: Concentration measuring device

Claims (15)

A photoreceptor,
A collection unit for collecting a liquid developer from the photoreceptor;
A storage unit for storing the liquid developer in the recovery unit;
A density adjustment unit;
A first transport unit that transports the liquid developer from the storage unit to the density adjustment unit;
A liquid developer recovery system comprising: A waste tank,
A second transport unit that transports the liquid developer from the storage unit to the waste tank;
The liquid developer recovery system according to claim 1, comprising: A plurality of photoreceptors;
A collecting unit for collecting a liquid developer disposed on at least one of the plurality of photoconductors;
One or more storage units for storing the liquid developer recovered by the recovery unit;
A density adjustment unit;
A transport unit for transporting the liquid developer from the storage unit to the density adjusting unit;
A liquid developer recovery system comprising: The image forming apparatus includes a transfer member to which an image formed by the plurality of photoconductors is transferred, and the storage unit is recovered by a photoconductor that forms an image transferred to the transfer member as a first of the plurality of photoconductors. 5. The liquid developer recovery system according to claim 4, wherein the liquid developer is a storage unit for storing the liquid developer. 3. The liquid developer recovery system according to claim 1, wherein the storage unit has a storage unit for the liquid developer recovered by each of the plurality of photoconductors. 4. A storage unit liquid level sensor disposed in the storage unit;
A concentration adjusting unit liquid level sensor arranged in the concentration adjusting unit;
A density sensor arranged in the density adjustment unit;
A distribution unit that distributes the first transfer unit and the second transfer unit;
A control unit that controls the distribution unit based on at least one data of the storage unit liquid level sensor, the concentration adjustment unit liquid level sensor, and the concentration sensor;
The liquid developer recovery system according to claim 2, further comprising: The liquid developer recovery system according to claim 6, wherein the distribution unit is a switching valve. The liquid developer recovery system according to claim 6, wherein the distribution unit is a drive pump disposed in the first conveyance unit and the second conveyance unit. A plurality of photoreceptors on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image with a liquid developer to form an image;
A transfer member to which an image of the photoreceptor is transferred;
A collection unit for collecting a liquid developer from the photoreceptor;
One or more storage units for storing the liquid developer recovered by the recovery unit;
A density adjustment unit;
A first transport unit that transports the liquid developer from the storage unit to the density adjustment unit;
An image forming apparatus comprising: The image forming apparatus according to claim 9, further comprising a second transport unit that transports the liquid developer from the storage unit to a waste tank. 11. The image according to claim 9, wherein the storage unit is a storage unit that stores a liquid developer collected by a photoconductor that forms an image transferred to a transfer member in a first of the plurality of photoconductors. Forming equipment. The image forming apparatus according to claim 9, wherein the storage unit has a storage unit for the liquid developer collected by each of the plurality of photoconductors. A storage unit liquid level sensor disposed in the storage unit;
A concentration adjusting unit liquid level sensor arranged in the concentration adjusting unit;
A density sensor arranged in the density adjustment unit;
A distribution unit that distributes the first transfer unit and the second transfer unit;
A control unit that controls the distribution unit based on at least one data of the storage unit liquid level sensor, the concentration adjustment unit liquid level sensor, and the concentration sensor;
The image forming apparatus according to claim 10, comprising: The image forming apparatus according to claim 13, wherein the distribution unit is a switching valve. The image forming apparatus according to claim 13, wherein the distribution unit is a drive pump disposed in the first conveyance unit and the second conveyance unit.

Images