JP2012215752A - Development device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a development device and an image formation device capable of correcting a detection result of an electrostatic capacitance detection section and acquiring accurate liquid level information.SOLUTION: A development device comprises: a storage section 401Y which stores liquid developer containing toner as well as a carrier; a capacitance type liquid level sensor 410Y which detects electrostatic capacitance with a first sensor electrode 421Y provided in the storage section 401Y and a second sensor electrode 422Y arranged opposite to the first sensor electrode 421Y through the liquid developer; a density sensor 460Y which is arranged in the storage section 401Y and detects toner density in the liquid developer; and a liquid level calculation section which calculates a liquid level of the liquid developer stored in the storage section 401Y based on the electrostatic capacitance detected by the capacitance type liquid level sensor 410Y and the toner density detected by the density sensor 460Y.

Description

  In the present invention, a latent image formed on a photoreceptor is developed with a liquid developer composed of toner and carrier, and a developed image composed of toner and carrier by the developer is further transferred to a recording medium and transferred. The present invention relates to an image forming apparatus for fusing and fixing a toner image to form an image.

  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 developer used in this wet image forming apparatus suspends solids (toner particles) in a highly viscous organic solvent (carrier liquid) having electrical insulation properties such as silicone oil, mineral oil, and edible oil. The toner particles are extremely fine with a particle diameter of around 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 the developing unit of the image forming apparatus using the liquid developer as described above, in order to grasp the remaining amount of the liquid developer and the like, the liquid level of the liquid developer in the storage unit that stores the liquid developer is detected. Various techniques have been proposed.

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-194208) discloses a substrate, a first electrode plate supported so as to be spaced apart from the substrate by a predetermined distance, and a height of the first electrode plate from the substrate. A second electrode plate having an opening corresponding to an outer peripheral surface of the first electrode plate, and provided at a predetermined detection position on one side of a container in which a solution to be detected is stored. And a water storage level detection unit for detecting the presence or absence of the solution on the detection position from a change in capacitance measured by the first electrode plate and the second electrode plate. A water storage level detector is disclosed.
JP 2001-194208 A

  When the determination regarding the liquid level of the liquid developer is performed based on the change in capacitance measured by the first electrode plate and the second electrode plate as described in the prior art, the capacitance However, in the conventional technology, the influence of the change in capacitance due to the concentration on the liquid level detection result is taken into consideration. There is a problem that accurate liquid level information cannot be acquired.

  The present invention is for solving the above-described problems, and a developing device according to the present invention includes a storage unit that stores a liquid developer including toner and a carrier, a first electrode provided in the storage unit, and a storage unit in the storage unit. And a second electrode opposed to the first electrode with the liquid developer interposed therebetween, and a capacitance detecting unit for detecting a capacitance, and a toner concentration of the liquid developer disposed in the housing unit A liquid developer stored in the storage unit based on the density detection unit for detecting the density, the capacitance detected by the capacitance detection unit, and the toner concentration detected by the density detection unit And a liquid level calculation unit for calculating the liquid level.

The developing device according to the present invention further includes a temperature detection unit that detects a temperature of the liquid developer stored in the storage unit, and the liquid level calculation unit is configured to adjust the temperature detected by the temperature detection unit. Based on this, the liquid level of the liquid developer stored in the storage unit is calculated.

  Further, in the developing device according to the present invention, the liquid level calculation unit corrects the toner concentration detected by the concentration detection unit based on the temperature detected by the temperature detection unit.

  The image forming apparatus according to the present invention includes a latent image carrier on which a latent image is formed, an exposure unit that exposes the latent image carrier to form the latent image, and a liquid developer that includes toner and a carrier. A first container provided in the container and a second electrode provided in the container and opposed to the first electrode through a liquid developer to detect electrostatic capacitance. A capacity detector, a developer detector that stores a liquid developer, and a liquid developer that is supplied from the developer reservoir, includes a density detector that is disposed in the storage unit and detects a toner concentration of the liquid developer. A developer carrying member for carrying the developer, and a supply member for supplying a liquid developer to the developer carrying member, and developing the latent image formed on the latent image carrying member; The capacitance detected by the capacitance detector and the concentration detector Based on the toner density that is characterized by and a liquid level calculation unit for calculating a liquid level of the liquid developer to be accommodated in the accommodation section.

  The image forming apparatus according to the present invention further includes a temperature detection unit that detects a temperature of the liquid developer stored in the storage unit, and the liquid level calculation unit is detected by the temperature detection unit. Based on the temperature, the liquid level of the liquid developer stored in the storage unit is calculated.

  In the image forming apparatus according to the aspect of the invention, the liquid level calculation unit corrects the toner concentration detected by the concentration detection unit based on the temperature detected by the temperature detection unit.

  The image forming apparatus according to the present invention includes a developer storage tank that stores a liquid developer having a first toner concentration, a carrier liquid storage tank that stores a carrier liquid, and the developer storage tank that stores the carrier liquid. A second toner concentration in which the liquid developer or carrier liquid having the first toner concentration is supplied and the toner concentration of the liquid developer stored in the storage portion of the developer storage portion is lower than the first toner concentration. And a control unit for controlling.

  As described above, according to the developing device and the image forming apparatus of the present invention, the liquid level calculation unit detects the liquid level of the liquid developer stored in the storage unit, and detects the capacitance and concentration detected by the capacitance detection unit. Therefore, accurate liquid level information can be acquired.

1 is a diagram illustrating main components constituting an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating main components of an image forming unit and a developing device. It is sectional drawing which shows the outline of a structure of the tank for density adjustment in a developing device. It is a figure explaining the measurement principle of an electrostatic capacitance type liquid level sensor. It is a figure which shows the relationship between the liquid level calculated | required from the measurement principle of an electrostatic capacitance type liquid level sensor, and an electrostatic capacitance. It is a figure which shows the temperature characteristic of the electrostatic capacitance of the capacitor | condenser C which an electrostatic capacitance type liquid level sensor forms. FIG. 6 is a diagram showing an outline of a relationship between a dielectric constant ε _dev and a concentration of a liquid developer. FIG. 3 is a block diagram for liquid level control in the developing device according to the first embodiment of the present invention. It is a block diagram of a concentration / liquid level control unit in the developing device according to the embodiment of the present invention. It is a figure which shows the flowchart from the density | concentration and liquid level measurement in 1st Embodiment to the replenishment amount determination. It is a figure which shows the flowchart of the subroutine of density | concentration and a liquid level control. It is a figure which shows the switch of control by a density | concentration and a liquid level range. It is a figure which shows the switching of the control based on the state A thru | or D. FIG. It is a block diagram for liquid level control in the developing device according to the second embodiment of the present invention. It is a figure which shows the flowchart from the density | concentration and liquid level measurement in 2nd Embodiment to the replenishment amount determination. It is a block diagram for liquid level control in the developing device concerning a 3rd embodiment of the present invention. It is a figure which shows the flowchart from the density | concentration and liquid level measurement in 3rd Embodiment to the replenishment amount determination. It is a block diagram for liquid level control in the developing device concerning a 4th embodiment of the present invention. It is a figure which shows the flowchart from the density | concentration and liquid level measurement in 4th Embodiment to the replenishment amount determination.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing main components constituting the image forming apparatus according to the embodiment of the present invention. The developing devices 30Y, 30M, 30C, and 30K are arranged at the lower portion of the image forming apparatus, and the transfer belt 40, the secondary transfer section (secondary transfer section) (secondary transfer section) The unit 60 is disposed at the top of the image forming apparatus.

  The image forming unit includes photoreceptors 10Y, 10M, 10C, and 10K, corona chargers 11Y, 11M, 11C, and 11K, and exposure units 12Y, 12M, 12C, and 12K (not shown). The photoconductors 10Y, 10M, 10C, and 10K are uniformly charged by the corona chargers 11Y, 11M, 11C, and 11K, and are mounted on the exposure units 12Y, 12M, 12C, and 12K based on the input image signals. By driving the exposure head, an electrostatic latent image is formed on the charged photoreceptors 10Y, 10M, 10C, and 10K.

  The developing devices 30Y, 30M, 30C, and 30K generally include liquid developers of respective colors including the developing rollers 20Y, 20M, 20C, and 20K, yellow (Y), magenta (M), cyan (C), and black (K). Developer containers (reservoirs) 31Y, 31M, 31C, 31K to be stored, and application rollers for applying liquid developers of these colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K. The anilox rollers 32Y, 32M, 32C, 32K and the like are provided, and the electrostatic latent images formed on the photoreceptors 10Y, 10M, 10C, 10K are developed with the liquid developers of the respective colors.

  The transfer belt 40 is an endless belt, is stretched between the driving roller 41 and the tension roller 42, and is in contact with the photoreceptors 10Y, 10M, 10C, and 10K by the primary transfer units 50Y, 50M, 50C, and 50K. It is rotationally driven by the drive roller 41. In the primary transfer portions 50Y, 50M, 50C, and 50K, the primary transfer rollers 51Y, 51M, 51C, and 51K are arranged to face each other with the transfer belt 40 sandwiched between the photoreceptors 10Y, 10M, 10C, and 10K. The developed toner images of the respective photoreceptors 10Y, 10M, 10C, and 10K are sequentially superimposed and transferred onto the transfer belt 40 using the contact position with 10K as the transfer position to form a full-color toner image.

In the secondary transfer unit 60, a secondary transfer roller 61 is disposed opposite to the belt driving roller 41 with the transfer belt 40 interposed therebetween, and a cleaning device including a secondary transfer roller cleaning blade 62 is disposed. Then, at the transfer position where the secondary transfer roller 61 is disposed, recording of a sheet of paper, film, cloth, etc., on which a single color toner image or a full color toner image formed on the transfer belt 40 is conveyed through the sheet material conveyance path L. Transfer to media.

  Further, a fixing unit 90 is disposed downstream of the path sheet material conveyance path L, and a single-color toner image or a full-color toner image transferred onto a recording medium such as paper is fused and fixed on the recording medium such as paper. Let

  Further, the tension roller 42 stretches the transfer belt 40 together with the belt driving roller 41, and the cleaning device including the transfer belt cleaning blade 46 is brought into contact with the tension roller 42 at a portion stretched on the tension roller 42 of the transfer belt 40.・ It is arranged.

  Next, the image forming unit and the developing device of the image forming apparatus according to the embodiment of the present invention will be described. FIG. 2 is a sectional view showing main components of the image forming unit and the developing device. Since the configurations of the image forming unit and the developing device for each color are the same, the following description is based on the yellow (Y) image forming unit and the developing device.

  The image forming unit includes a photoconductor cleaning blade 18Y, a corona charger 11Y, an exposure unit 12Y, a developing roller 20Y of the developing device 30Y, a photoconductor squeeze roller 13Y, and a photoconductor squeeze roller along the rotation direction of the outer periphery of the photoconductor 10Y. 13Y ′ is arranged. In addition, cleaning devices including photosensitive member squeeze roller cleaning blades 14Y and 14Y 'are disposed as accessory components on the photosensitive member squeeze rollers 13Y and 13Y'.

  A cleaning blade 21Y, an elastic roller 16Y, and a toner compression corona generator 22Y are arranged on the outer periphery of the developing roller 20Y in the developing device 30Y. The elastic roller 16Y is in contact with the anilox roller 32Y, and the anilox roller 32Y is in contact with a regulating blade 33Y for adjusting the amount of liquid developer supplied to the developing roller 20Y.

  An elastic roller cleaning blade 17Y that scrapes off the liquid developer that is not supplied to the developing roller 20Y but remains on the elastic roller 16Y is in contact with the elastic roller 16Y.

  The liquid developer container 31Y is partitioned into two spaces, a supply storage unit 310Y and a recovery storage unit 320Y, by a partition unit 330Y. The supply storage unit 310Y includes an auger 34Y for supplying liquid developer and a recovery storage. The portion 320Y accommodates a recovery auger 321Y for recovering the liquid developer.

  In addition, a primary transfer roller 51Y of the primary transfer portion is disposed along the transfer belt 40 at a position facing the photoconductor 10Y.

  The photoconductor 10Y is a photoconductor drum made of a cylindrical member that is wider than the developing roller 20Y and has a photosensitive layer formed on the outer peripheral surface thereof. For example, the photoconductor 10Y rotates clockwise as shown in FIG. The photosensitive layer of the photoreceptor 10Y is composed of an organic photoreceptor or an amorphous silicon photoreceptor. The corona charger 11Y is disposed upstream of the nip portion between the photoconductor 10Y and the developing roller 20Y in the rotation direction of the photoconductor 10Y, and a voltage is applied from a power supply device (not shown) to corona-charge the photoconductor 10Y. The exposure unit 12Y irradiates light onto the photoconductor 10Y charged by the corona charger 11Y downstream of the corona charger 11Y in the rotation direction of the photoconductor 10Y, thereby forming a latent image on the photoconductor 10Y.

  Note that, from the beginning to the end of the image forming process, the configuration of the rollers and the like arranged in the preceding stage is defined to be upstream from the configuration of the rollers and the like arranged in the subsequent stage.

  In the supply storage unit 310Y of the developing device 30Y, the liquid developer in a state where the toner is dispersed in an approximate weight ratio of about 25% is stored in the carrier. On the other hand, in the collecting and storing unit 320Y of the developing device 30Y, the liquid developer that has not been supplied to the anilox roller 32Y, the liquid developer that has been scraped off by the photoreceptor squeeze roller cleaning blades 14Y and 14Y ′, and the developing by the cleaning blade 21Y. A recovery auger 321Y that recovers the liquid developer scraped off from the roller 20Y, the liquid developer scraped off from the elastic roller 16Y by the elastic roller cleaning blade 17Y, and the like is also provided.

  Further, the developing device 30Y is provided with a toner compression corona generator 22Y that performs a compaction action. The toner compression corona generator 22Y applies a bias voltage to the liquid developer on the developing roller 20Y in order to improve the developing efficiency, thereby compressing the toner in the liquid developer.

  The developing device 30Y includes a developing roller 20Y that carries the liquid developer, an elastic roller 16Y that supplies the liquid developer to the developing roller 20Y, and an anilox roller 32Y that is a roller for applying the liquid developer to the elastic roller 16Y. A regulating blade 33Y that regulates the amount of liquid developer applied to the developing roller 20Y, an auger 34Y that supplies the anilox roller 32Y while stirring and transporting the liquid developer, and a liquid developer carried on the developing roller 20Y in a compacted state. A toner compression corona generator 22Y and a developing roller cleaning blade 21Y for cleaning the developing roller 20Y. Note that the compaction state means that the toner component in the liquid developer is compressed to the surface side of the developing roller 20Y.

  The liquid developer contained in the developer container 31Y is a low-concentration (about 1 to 3 wt%) and low-viscosity volatile at room temperature using a conventionally used Isopar (trademark: exon) as a carrier. Is a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility at room temperature.

That is, in the liquid developer in the present invention, a solid having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin is introduced into a liquid solvent such as an organic solvent, silicone oil, mineral oil, or edible oil. High viscosity (HAAKE) with toner solid content concentration of about 25%.
A liquid developer using RheoStress RS600 and having a viscoelasticity of about 30 to 300 mPa · s when the shear rate at 25 ° C. is 1000 (1 / s).

  More specifically, the liquid developer in the present invention is obtained by dispersing at least a binder resin in a liquid silicone oil having a viscosity of 0.5 to 1,000 mPa · s (25 ° C.). HAAKE RheoStress RS600 The viscoelasticity when the shear rate at 25 ° C. is 1000 (1 / s) is 30 to 300 mPa · s (25 ° C.).

  The liquid silicone oil is a low volatility carrier liquid and is selected from the group consisting of a liquid silicone having a linear structure, a liquid silicone having a cyclic structure, a liquid silicone having a branched structure, or a combination thereof.

  Examples of the liquid silicone oil include DC 200 Fluid (20 cSt), DC 200 Fluid (100 cSt), DC 200 Fluid (50 cSt), and DC 345 Fluid by Dow Corning, USA.

  Examples of pigments include organic colorants such as nigrosine, phthalocyanine blue and quinacridone, and inorganic colorants such as carbon black and iron oxide. Binder resins include epoxy resins, polyacrylates and polyesters. Or a copolymer thereof, alkyd resin, rosin, rosin ester, modified epoxy resin, polyvinyl acetate resin, styrene-butadiene resin, cyclized rubber, ethylene-vinyl acetate copolymer, polyethylene and the like.

  The pigment and the binder resin may be directly dispersed in the liquid silicone oil, but preferably the pigment and the binder resin are melt-kneaded to form a pigment coated with the binder resin.

  Examples of resin-coated pigments include Araldite 6084 (CI Pigment Blue 15: 3 by Ciba-Geigy), Tintcarb 435 (CI Pigment Black 7 by Cabot Corporation), Irgalite Rubine coated with epoxy resin. KB4N (CI Pigment Red 57 by Ciba-Geigy), Monolite Yellow (CI Pigment Yellow 1 by ICI Australia), and the like. These coated pigments may be mixed at an appropriate ratio, and then melt-kneaded and pulverized to form a master batch, which is used for producing a liquid developer described later. Alternatively, a masterbatch in which an alkylated polyvinylpyrrolidone is added and reacted with the epoxy resin at the time of melt-kneading the pigment coated with the epoxy resin, and the coating resin is a modified epoxy resin may be used.

  The dispersant is a polysiloxane having a functional group selected from a vinyl group, a carboxylic acid group, a hydroxyl group, and an amine group, and includes a linear polysiloxane, a cyclic polysiloxane, a branched polysiloxane, and combinations thereof. Selected. For example, Elastsil M4640A (manufactured by Wacker Chemical Co., polysiloxane polymer having a vinyl functional group), Finish WR1101 (manufactured by Wacker Chemical Co., polysiloxane polymer having an amine functional group), and having a viscosity of 90,000 mPa · s or less. Are illustrated. The polysiloxane having a functional group is bonded or adsorbed on the surface of the colored resin particle through the functional group, thereby imparting compatibility with the liquid silicone oil to the colored particle.

  Further, the liquid developer of the present invention can contain a charge control agent such as metal soap, fatty acid, lecithin as needed, and examples include Nuxtra 6% Zirconium (made by Clearnova, zirconium octoate) and the like. The

  The liquid developer of the present invention is prepared by pulverizing and mixing the master batch, the dispersant and the liquid silicone oil obtained above with a ball mill, and has a viscosity of 30 to 300 mPa · s (25 ° C.). Good. The toner solid content concentration is 40% by mass or less, preferably 10 to 25% by mass. In the present embodiment, a liquid developer having a toner solid content concentration of 25% by mass is accommodated in the developer container 31Y.

  As the liquid developer of the present invention, the liquid developer described in JP-T-2003-508826 may be used, and the description is referred to for details. However, in the present invention, the liquid developer is used. The glass transition point (Tg) of the binder resin in is preferably 40 ° C to 70 ° C.

The anilox roller 32Y functions as an application roller that supplies and applies a liquid developer to the elastic roller 16Y. The anilox roller 32Y is a cylindrical member, and is a roller having a concave and convex surface formed by grooves engraved finely and uniformly on the surface so as to easily carry the liquid developer on the surface. The anilox roller 32Y supplies the liquid developer from the developer container 31Y to the developing roller 20Y. During the operation of the apparatus, as shown in FIG. 2, the auger 34Y rotates counterclockwise to supply the liquid developer to the anilox roller 32Y, and the anilox roller 32Y rotates clockwise and rotates counterclockwise. A liquid developer is applied to the elastic roller 16Y. The liquid developer applied to the elastic roller 16Y by the anilox roller 32Y is supplied to the developing roller 20Y that rotates counterclockwise.

  The regulating blade 33Y is a metal blade having a thickness of about 200 μm, abuts against the surface of the anilox roller 32Y, regulates the film thickness and amount of the liquid developer carried and conveyed by the anilox roller 32Y, and is applied to the elastic roller 16Y. Adjust the amount of liquid developer to be supplied.

  The developing roller 20Y is a cylindrical member, and rotates counterclockwise around the rotation axis as shown in FIG. The developing roller 20Y is provided with an elastic layer made of polyurethane rubber, silicon rubber, NBR or the like on the outer peripheral portion of an inner core made of metal such as iron, and further provided with a coating of PFA or urethane coat on the elastic layer. The developing roller cleaning blade 21Y is made of rubber or the like that contacts the surface of the developing roller 20Y. The developing roller 20Y is disposed downstream of the developing nip portion where the developing roller 20Y contacts the photoreceptor 10Y in the rotation direction of the developing roller 20Y. The liquid developer remaining on the roller 20Y is scraped off and removed. Here, the liquid developer that has been scraped off falls into the collection storage section 320Y of the developing device 30Y.

  As for the elastic roller 16Y, an elastic layer such as polyurethane rubber, silicon rubber, NBR or the like is provided on the outer peripheral portion of an inner core made of metal such as iron, and further, this elastic layer is provided with a coating of PFA or urethane coat. The elastic roller cleaning blade 17Y scrapes off and removes the liquid developer remaining on the elastic roller 16Y. Here, the liquid developer that has been scraped off falls into the collection storage section 320Y of the developing device 30Y.

  The toner compression corona generator 22Y is an electric field applying means for increasing the charging bias on the surface of the developing roller 20Y. The liquid developer conveyed by the developing roller 20Y is fed by the toner compression corona generator 22Y as shown in FIG. An electric field is applied from the toner compression corona generator 22Y side toward the developing roller 20Y at the toner compression portion.

  The liquid developer carried on the developing roller 20Y and compressed by toner moves in correspondence with the latent image on the photoconductor 10Y by applying a desired electric field in the developing nip where the developing roller 20Y contacts the photoconductor 10Y. Develop. Then, the developer remaining after development is scraped off and removed by the developing roller cleaning blade 21Y and dropped into the collection storage unit 320Y in the developer container 31Y to be reused.

  The photosensitive member squeeze device disposed upstream of the primary transfer is disposed downstream of the developing roller 20Y so as to face the photosensitive member 10Y, and collects excess developer of the toner image developed on the photosensitive member 10Y. As shown in FIG. 2, the photosensitive member squeeze rollers 13Y and 13Y ′ formed of an elastic roller member that is covered with an elastic member and rotates in sliding contact with the photosensitive member 10Y, and the photosensitive member squeeze rollers 13Y and 13Y ′ are provided. The cleaning blades 14Y and 14Y ′ for cleaning the surface by pressing and sliding contact, recovering excess carrier and originally unnecessary fog toner from the liquid developer developed on the photoreceptor 10Y, and the toner particle ratio in the visible image It has a function to raise. In this embodiment, a plurality of photosensitive member squeeze rollers 13Y and 13Y 'are provided as the photosensitive member squeeze device before the primary transfer. However, a single photosensitive member squeeze roller may be used. Further, one of the plurality of photosensitive member squeeze rollers 13Y and 13Y 'may be configured to come into contact with and come into contact with each other depending on the state of the liquid developer.

In the primary transfer unit 50Y, the developer image developed on the photoreceptor 10Y is transferred to the primary transfer roller 51Y.
To transfer to the transfer belt 40. Here, the photoconductor 10Y and the transfer belt 40 are configured to move at a constant speed, and the driving load of rotation and movement is reduced, and the disturbance effect on the visible toner image of the photoconductor 10Y is suppressed.

  On the downstream side of the primary transfer, the photoconductor cleaning blade 18Y that is in contact with the photoconductor 10Y cleans the liquid developer remaining on the photoconductor 10Y without being transferred. The liquid developer scraped off by the photoreceptor cleaning blade 18Y falls on the developer storage base 280. The developer storage base 280 is provided with a rotating recovery auger 281, and the liquid developer stored in the developer storage base 280 is guided to the recycled developer recovery pipe 285 as the recovery auger 281 rotates. It reaches the buffer tank 530Y through the recycled developer recovery pipe 285.

  The developing device 30Y is provided with a concentration adjusting tank 400Y that supplies a liquid developer in which toner is dispersed to a carrier at an approximate weight ratio of 25% with respect to the supply storage unit 310Y in the developer container 31Y. A liquid developer supply pipe 370Y is provided between the density adjustment tank 400Y and the supply storage section 310Y, and is driven by a liquid developer supply pump 375Y disposed in the middle of the liquid developer supply pipe 370Y. The liquid developer whose concentration in the concentration adjustment tank 400Y is adjusted is supplied to the supply storage unit 310Y.

  Further, a liquid developer recovery pipe 371Y is provided between the density adjustment tank 400Y and the recovery reservoir 320Y in the developer container 31Y, and the liquid developer scraped off by each cleaning blade is stored. When the collection auger 321Y rotates in the collection storage unit 320Y, the liquid developer is guided to the liquid developer collection pipe 371Y and falls into the density adjustment tank 400Y.

  The high-concentration developer tank 510Y is a tank that stores a high-concentration liquid developer having a toner solid content concentration of about 35% or more, and the carrier liquid tank 520Y is a tank that stores a carrier stock solution.

  A high density developer supply pipe 511Y is provided between the high density developer tank 510Y and the density adjustment tank 400Y, and the high density developer supply pump 513Y in the high density developer supply pipe 511Y is driven. Thus, the high-concentration liquid developer can be supplied from the high-concentration developer tank 510Y to the concentration adjustment tank 400Y. When the toner solid concentration of the liquid developer in the density adjustment tank 400Y falls below 25%, the high density developer supply pump 513Y is driven to supply the high density liquid developer to the density adjustment tank 400Y. However, the concentration can be increased.

  A carrier liquid supply pipe 521Y is provided between the carrier liquid tank 520Y and the concentration adjustment tank 400Y. When the carrier liquid supply pump 523Y in the carrier liquid supply pipe 521Y is driven, the carrier liquid tank 520Y The carrier solution stock solution can be supplied to the concentration adjusting tank 400Y. When the toner solid content concentration of the liquid developer in the density adjustment tank 400Y exceeds 25%, the carrier liquid supply pump 523Y is driven to supply the carrier liquid stock solution to the density adjustment tank 400Y. Can be lowered.

  Further, a recycled developer supply pipe 531Y is provided between the buffer tank 530Y storing the liquid developer recovered from the developer storage base 280 and the density adjusting tank 400Y. By driving the recycled developer supply pump 533Y in the tube 531Y, the recycled liquid developer can be supplied from the buffer tank 530Y to the density adjusting tank 400Y.

  Since the liquid developer stored in the buffer tank 530Y is a liquid developer scraped off from the photoreceptor 10Y after the secondary transfer, the toner solid content concentration is extremely low (toner solid content concentration of about About 3%) and carrier-rich. Accordingly, when the toner solid content concentration of the liquid developer in the density adjustment tank 400Y exceeds 25%, the density adjustment is performed from the buffer tank 530Y instead of supplying the carrier liquid from the carrier liquid tank 520Y to the density adjustment tank 400Y. When the liquid developer is supplied to the tank 400Y, the carrier liquid stock solution in the carrier liquid tank 520Y may be saved.

  Next, the configuration of the concentration adjustment tank 400Y will be described in more detail. FIG. 3 is a cross-sectional view schematically showing the configuration of the density adjusting tank in the developing device. The density adjusting tank 400Y is a tank used for preparing a liquid developer used in the developing process in the developing device 30.

  The density adjustment tank 400Y includes a storage portion 401Y that stores the liquid developer, and a cover portion 402Y that covers the storage portion 401Y and through which each pipe, shaft portion 406Y, support member 451Y, and the like are inserted. ing.

  A motor 405Y is attached to the lid portion 402Y. A shaft portion 406Y that is a rotation shaft of the motor 405Y is inserted from the lid portion 402Y into the housing portion 401Y. A stirring blade 407Y is attached to the shaft portion 406Y at a position where it is assumed to be immersed in the liquid developer, and the stirring blade 407Y rotates as the motor 405Y operates to stir the liquid developer in the housing portion 401Y. It has come to be.

  A capacitive liquid level sensor 410Y used to detect the liquid level of the liquid developer in the concentration adjustment tank 400Y is provided on the side surface of the container 401Y of the concentration adjustment tank 400Y. The capacitance type liquid level sensor 410Y forms a capacitor by the first sensor electrode 421Y and the second sensor electrode 422Y facing each other, and detects the liquid level of the liquid developer from the capacitance of the capacitor. The capacitance type liquid level sensor 410Y includes a first spacer 423Y and a second spacer 424Y as distance regulating members for maintaining a constant distance between the first sensor electrode 421Y and the second sensor electrode 422Y. It is arranged between the counter electrodes. The first sensor electrode 421Y is attached to the housing portion 401Y via the attachment base 411Y and the attachment base 412Y.

  The first sensor electrode 421Y and the second sensor electrode 422Y are made of materials such as stainless steel (SUS304, SUS430), iron, aluminum (A5052, A6063). The surfaces of the first sensor electrode 421Y and the second sensor electrode 422Y may be coated with polytetrafluoroethylene (trade name Teflon) or the like.

  In addition, as materials used for the first spacer 423Y and the second spacer 424Y which are members for determining the distance between the electrodes, polyethylene, polyethylene terephthalate, polystyrene, polypropylene, AS resin, ABS resin, polyamide, polycarbonate, polyacetal resin, etc. An insulator can be mentioned.

FIG. 4 is a diagram for explaining the measurement principle of the capacitive liquid level sensor. The first sensor electrode 421Y and the second sensor electrode 422Y have the same shape, the electrode width is w, and the electrode length is l. Further, the first sensor electrode 421Y and the second sensor electrode 422Y are arranged to face each other with a distance d. Further, when the liquid level is L, if the dielectric constant of _air is ε _air and the dielectric constant of the liquid developer is ε _dev , the capacitor C _air using air as a dielectric can be expressed by the following equation (1). it can.

また、液体現像剤を誘電体としたコンデンサＣ_devは、下式（２）によって表すことがで
きる。

The capacitor C _dev using a liquid developer as a dielectric can be expressed by the following equation (2).

したがって、液位Ｌによって、第１センサー電極４２１Ｙと第２センサー電極４２２Ｙとが形成するコンデンサＣの値は、下式（３）によって変化することがわかる。

Therefore, it can be seen that the value of the capacitor C formed by the first sensor electrode 421Y and the second sensor electrode 422Y varies according to the liquid level L according to the following equation (3).

図５は静電容量式液位センサー４１０Ｙの測定原理から求められる液位と静電容量との関係を示す図である。上記の（３）式に示す測定原理から、濃度調整用タンク４００Ｙにおける液位と、第１センサー電極４２１Ｙと第２センサー電極４２２Ｙとが形成するコンデンサＣの静電容量には、図示するように１次式の関係があることがわかる。

FIG. 5 is a diagram showing the relationship between the liquid level and the capacitance obtained from the measurement principle of the capacitive liquid level sensor 410Y. From the measurement principle shown in the above equation (3), the liquid level in the concentration adjustment tank 400Y and the capacitance of the capacitor C formed by the first sensor electrode 421Y and the second sensor electrode 422Y are as shown in the figure. It can be seen that there is a linear relationship.

By the way, it was found that the dielectric constant ε _dev of the liquid developer used in this embodiment has a change in capacitance depending on the temperature. Accordingly, based on such a change, the capacitance of the capacitor C formed by the first sensor electrode 421Y and the second sensor electrode 422Y changes as shown in FIG. 6 according to the change in temperature. The relational expression between temperature and capacitance in FIG. 6 can be approximated by a quadratic expression.

Further, the dielectric constant ε _dev of the liquid developer used in the present embodiment changes according to the toner solid content concentration dispersed in the carrier liquid. FIG. 7 is a diagram schematically showing the relationship between the dielectric constant ε _dev and the concentration of the liquid developer. As shown in FIG. 7, it can be seen that as the concentration of the liquid developer increases, the dielectric constant ε _dev of the liquid developer also tends to increase.

  As described above, in the capacitance type liquid level sensor 410Y, the capacitance of the capacitor C varies depending on the temperature and concentration of the liquid developer, so the liquid level L is calculated based on the capacitance of the capacitor C. In this case, correction according to temperature and density is performed.

    Returning to FIG. 3 again, the lid portion 402Y is provided with a fixing member 450Y. The support member 451Y extending from the fixing member 450Y through the lid portion 402Y includes a concentration sensor 460Y and a temperature sensor 490Y. Is provided.

  As the density sensor 460Y, for example, a sensor that transmits and receives ultrasonic waves using two piezoelectric elements arranged opposite to each other and measures the density from the propagation time can be used. The temperature sensor 490Y is temperature detection means such as a platinum sensor.

The detection signals from the capacitive liquid level sensor 410Y, the concentration sensor 460Y, and the temperature sensor 490Y are all taken out of the concentration adjustment tank 400Y through lead wires (not shown).

  Next, the liquid level of the liquid developer in the concentration adjustment tank 400 of the developing device 30 according to the present embodiment configured as described above is roughly calculated as follows.

  For example, a general-purpose information processing apparatus including a CPU, a ROM that stores a program that operates on the CPU, and a RAM that is a work area of the CPU is used as the liquid level calculation unit. For this liquid level calculation unit, the capacitance data between the electrodes detected by the capacitive liquid level sensor 410Y constituted by the first sensor electrode 421Y and the second sensor electrode 422Y, and the concentration sensor 460Y. The data related to the concentration of the liquid developer detected by the above and the data related to the temperature of the liquid developer detected by the temperature sensor 490Y are input.

  The liquid level calculation unit 650 calculates the liquid level of the liquid developer stored in the storage unit 401Y based on the input data as described above, and the high concentration developer supply pump 513Y and the carrier liquid supply pump 523Y. Then, the liquid level data calculated is transmitted to a host controller that controls the recycled developer supply pump 533Y and the like.

  In the liquid level calculation unit 650, the capacitance data between the electrodes detected by the capacitive liquid level sensor 410Y is the most basic in calculating the liquid level of the liquid developer in the storage unit 401Y. Since it is data, it is possible to calculate liquid level data only from this data.

  Further, if necessary, in addition to the capacitance data acquired by the capacitance type liquid level sensor 410Y, data related to the concentration of the liquid developer detected by the concentration sensor 460Y, detected by the temperature sensor 490Y. It is also possible to calculate liquid level data based on the data relating to the temperature of the liquid developer. In this case, the characteristics shown in FIGS. 6 and 7 are considered.

  In addition to the capacitance data acquired by the capacitance type liquid level sensor 410Y, if necessary, the liquid level is further determined based on the data relating to the temperature of the liquid developer detected by the temperature sensor 490Y. It is also possible to calculate data. In this case, the characteristics shown in FIG. 6 are considered.

  Further, if necessary, in addition to the capacitance data acquired by the capacitance type liquid level sensor 410Y, the liquid level is further determined based on the data relating to the concentration of the liquid developer detected by the concentration sensor 460Y. It is also possible to calculate data. In this case, the characteristics shown in FIG. 7 are considered.

  Next, a method for controlling the high-concentration developer supply pump 513Y and the carrier liquid supply pump 523Y will be described in more detail. FIG. 8 is a block diagram for liquid level control in the developing device according to the first embodiment of the present invention.

  The output value from the density sensor 460Y is temporarily stored in the memory 616Y. The output from the memory 616Y is input to the calculator 626Y. The calculator 626Y calculates the density based on a look-up table (LUT) representing the relationship between the voltage and the density. This density data is input to the calculator 621Y.

The output value from the capacitive liquid level sensor 410Y is temporarily stored in the memory 611Y. The output from the memory 611Y is input to the calculator 621Y. The calculator 621Y calculates the liquid level based on a look-up table (LUT) that represents the relationship between the voltage and concentration data and the liquid level. The liquid level data is input to the concentration / liquid level control unit 640Y.

  The concentration / liquid level control unit 640Y receives data from the calculator 621Y and the calculator 626Y. The concentration / liquid level control unit 640Y refers to the RAM 650Y, and according to these data, the motor control unit 660Y that operates the high concentration developer supply pump 513Y, the motor control unit 670Y that operates the carrier liquid supply pump 523Y, and the image A control command is transmitted to the image forming unit 680 responsible for formation.

  Here, the configuration of the concentration / liquid level control unit 640Y will be described in more detail. FIG. 9 is a block diagram of the concentration / liquid level control unit 640Y in the developing device according to the embodiment of the present invention.

  The concentration / liquid level control unit 640Y receives concentration target data, concentration data, liquid level data, upper limit liquid amount data, and lower limit liquid amount data. The liquid level data is compared with the upper limit liquid volume data and the lower limit liquid volume data by two comparators. The computing unit in the concentration / liquid level control unit 640Y performs processing based on a flow to be described later, and transmits a control command to each component.

  FIG. 10 shows a flowchart from the measurement of the concentration and liquid level to the determination of the replenishment amount in the first embodiment. First, measurement is performed by the density sensor 460Y (step S11), and the density is calculated from the output voltage of the density sensor 460Y based on a look-up table (LUT) representing the relationship between voltage and density (step S12). Subsequently, measurement is performed by the electrostatic capacitance type liquid level sensor 410Y (step S13), and the LUT representing the relationship between voltage, concentration and liquid level is obtained from the concentration value obtained in step S12 and the output voltage obtained in step S13. Based on this, the liquid level is calculated (step S14). Finally, the required replenishment amount is calculated in the concentration / liquid level control unit 640Y from the concentration value obtained in step S12 and the liquid level value obtained in step S14, and the input to the motor control unit is determined (step S15).

Next, the concentration / liquid level control subroutine in step S15 will be described in more detail.

  In the concentration / liquid level control according to the present invention, the carrier liquid and the high-concentration developer having a concentration of 35% are supplied to the concentration adjustment tank 400Y from the carrier liquid tank 520Y and the high-concentration developer tank 510Y, respectively. The purpose is to keep the concentration and the liquid level in the concentration adjusting tank 400Y within a certain range.

  The concentration of the liquid developer is a target value (25%) and an allowable range (± 1%) in order to maintain the image quality, and the liquid level is sufficient and sufficient for development without overflowing from the concentration adjustment tank 400Y. Therefore, a lower limit (70 mm) and an upper limit (130 mm) are determined. Therefore, the target value of the liquid level is set to the middle (100 mm) between the lower limit value and the upper limit value, and control is performed to adjust both the concentration and the liquid level to the target value.

  In the density / liquid level control, the supply amount of the carrier liquid and the high density developer is determined from the current density measured by the density sensor 460Y, the difference between the liquid level and the target value. However, when the liquid level is larger than the target value, the liquid level cannot be adjusted to the target value. Further, since the difference between the density of the high density developer is 35% and the density target value (25%) is small, when the density is higher than the target value, both the density and the liquid level may not be adjusted to the target value. . In this case, determine the supply amount of carrier liquid and high-concentration developer so that the liquid level does not exceed the upper limit value, the density is adjusted to the target value, and the difference between the liquid level and the target value is minimized. To do. If the current liquid level is large and the liquid level exceeds the upper limit when trying to adjust the concentration to the target value, the carrier level should not exceed the upper limit and the difference between the concentration and the target value should be small. The supply amount of the liquid and the high-density developer is determined.

  As described above, control is performed to keep the concentration and liquid level within a certain range, but depending on the printing conditions and image data, the concentration and liquid level may deviate from the target range.

Therefore, printing that does not satisfy the image quality requirement and overflow of the density adjustment tank 400Y are prevented by switching whether density adjustment or printing is possible depending on the values of density and liquid level. As shown in FIG. 12, the state is classified into four states A to B according to the values of the concentration and the liquid level, and the operation is switched as follows in each state.
(A) When both the concentration and the liquid level are within the target range, normal concentration / liquid level control is performed (steps S103 to S106).
(B) When the liquid level falls below the lower limit (step S108), or when the concentration is outside the target range and the liquid level has not reached the upper limit (step S107), the concentration / Only liquid level control is performed, and printing resumes when the concentration and liquid level return to within the target range.
(C) If the density is within the target range but the liquid level exceeds the upper limit value, the density adjustment is stopped and only printing is continued as long as the density is within the target range (steps S110 to S111).
(D) If the concentration deviates from the target range and the liquid level also exceeds the upper limit value, it is impossible to return the concentration in the concentration adjustment tank to the range, so the entire operation including printing and concentration adjustment Is stopped (steps S112 to S115).

  The above is summarized as shown in FIG.

  According to the developing device and the image forming apparatus of the present invention as described above, the liquid level calculation unit detects the liquid level of the liquid developer stored in the storage unit 401Y by the capacitive liquid level sensor 410Y. Since it is performed based on the capacitance and the concentration detected by the concentration sensor 460Y, accurate liquid level information can be acquired.

  Next, a second embodiment of the present invention will be described. FIG. 14 is a block diagram for liquid level control in the developing device according to the second embodiment of the present invention, and FIG. 15 is a diagram showing a flowchart from concentration and liquid level measurement to replenishment amount determination in the second embodiment. is there.

  The output value from the density sensor 460Y is temporarily stored in the memory 616Y. The output from the memory 616Y is input to the calculator 626Y. The calculator 626Y calculates the density based on a look-up table (LUT) representing the relationship between the voltage and the density. The concentration data is input to the concentration / liquid level control unit 640Y.

  The output value from the temperature sensor 490Y is temporarily stored in the memory 619Y. The output from the memory 619Y is input to the calculator 629Y. The computing unit 629Y calculates the temperature based on a look-up table (LUT) representing the relationship between voltage and temperature. This temperature data is input to the calculator 621Y.

  The output value from the capacitive liquid level sensor 410Y is temporarily stored in the memory 611Y. The output from the memory 611Y is input to the calculator 621Y. The calculator 621Y calculates the liquid level based on a look-up table (LUT) that represents the relationship between the voltage and temperature data and the liquid level. The liquid level data is input to the concentration / liquid level control unit 640Y.

The concentration / liquid level control unit 640Y receives data from the calculator 621Y and the calculator 626Y. The concentration / liquid level control unit 640Y refers to the RAM 650Y, and according to these data, the motor control unit 660Y that operates the high concentration developer supply pump 513Y, the motor control unit 670Y that operates the carrier liquid supply pump 523Y, and the image Image forming unit 68 responsible for formation
A control command is transmitted to 0.

  In FIG. 15, measurement is first performed by the density sensor 460Y (step S21), and the developer density is calculated from the sensor output voltage based on the LUT representing the relationship between the voltage and density (step S22). Next, measurement is performed by the temperature sensor 490Y (step S23), and the developer temperature is calculated from the sensor output voltage based on the LUT representing the relationship between the voltage and temperature (step S24).

  Subsequently, measurement is performed by the capacitance type liquid level sensor 410Y (step S25), and based on the temperature obtained in step S24 and the output voltage obtained in step S25, based on the LUT representing the relationship between voltage, temperature and liquid level. The liquid level is calculated (step S26). Finally, the required replenishment amount is calculated in the concentration / liquid level control unit from the concentration value obtained in step S22 and the liquid level value obtained in step S26, and the input to the motor control unit is determined (step S27). The processing in the concentration / liquid level control unit can be the same as in the first embodiment.

  According to the second embodiment as described above, the liquid level calculation unit determines the liquid level of the liquid developer stored in the storage unit 401Y by detecting the electrostatic capacity and temperature detected by the capacitive liquid level sensor 410Y. Since it is based on the temperature detected by the sensor 490Y, it is possible to acquire accurate liquid level information without being affected by the temperature change.

  Next, a third embodiment of the present invention will be described. FIG. 16 is a block diagram for liquid level control in the developing device according to the third embodiment of the present invention, and FIG. 17 is a diagram showing a flowchart from concentration and liquid level measurement to replenishment amount determination in the third embodiment. is there.

  The output value from the density sensor 460Y is temporarily stored in the memory 616Y. The output from the memory 616Y is input to the calculator 626Y. The calculator 626Y calculates the concentration based on a look-up table (LUT) representing the relationship between voltage, temperature and concentration. The concentration data is input to the concentration / liquid level control unit 640Y.

  The output value from the temperature sensor 490Y is temporarily stored in the memory 619Y. The output from the memory 619Y is input to the calculator 629Y. The computing unit 629Y calculates the temperature based on a look-up table (LUT) representing the relationship between voltage and temperature. This temperature data is input to the calculator 626Y.

  The output value from the capacitive liquid level sensor 410Y is temporarily stored in the memory 611Y. The output from the memory 611Y is input to the calculator 621Y. The calculator 621Y calculates the liquid level based on a look-up table (LUT) that represents the relationship between the voltage and the liquid level. The liquid level data is input to the concentration / liquid level control unit 640Y.

  The concentration / liquid level control unit 640Y receives data from the calculator 621Y and the calculator 626Y. The concentration / liquid level control unit 640Y refers to the RAM 650Y, and according to these data, the motor control unit 660Y that operates the high concentration developer supply pump 513Y, the motor control unit 670Y that operates the carrier liquid supply pump 523Y, and the image A control command is transmitted to the image forming unit 680 responsible for formation.

In FIG. 17, measurement is first performed by the temperature sensor 490Y (step S31), and the developer temperature is calculated from the sensor output voltage based on a look-up table (LUT) representing the relationship between voltage and temperature (step S32). Next, measurement is performed by the density sensor 460Y (step S33), and the developer density is determined from the temperature obtained in step S32 and the sensor output voltage obtained in step S33 on the basis of the LUT representing the relationship between voltage, temperature, and density. Calculate (step S34).
Subsequently, measurement is performed by the capacitive liquid level sensor 410Y (step S35), and the liquid level is calculated from the sensor output voltage based on the LUT representing the relationship between the voltage and the liquid level (step S36). Finally, the required replenishment amount is calculated in the concentration / liquid level control unit from the concentration value obtained in step S34 and the liquid level value obtained in step S36, and the input to the motor control unit is determined (step S37). The processing in the concentration / liquid level control unit can be the same as in the first embodiment.

  According to the third embodiment as described above, the concentration calculation unit calculates the concentration of the liquid developer stored in the storage unit 401Y based on the voltage detected by the concentration sensor 460Y and the temperature detected by the temperature sensor 490Y. Therefore, accurate density information can be acquired without being affected by temperature changes.

  Next, a fourth embodiment of the present invention will be described. FIG. 18 is a block diagram for liquid level control in the developing device according to the fourth embodiment of the present invention, and FIG. 19 is a diagram showing a flowchart from concentration and liquid level measurement to replenishment amount determination in the fourth embodiment. is there.

  The output value from the density sensor 460Y is temporarily stored in the memory 616Y. The output from the memory 616Y is input to the calculator 626Y. The calculator 626Y calculates the concentration based on a look-up table (LUT) that represents the relationship between the voltage and temperature data and the concentration. The concentration data is input to the concentration / liquid level control unit 640Y.

  The output value from the temperature sensor 490Y is temporarily stored in the memory 619Y. The output from the memory 619Y is input to the calculator 629Y. The computing unit 629Y calculates the temperature based on a look-up table (LUT) representing the relationship between voltage and temperature. This temperature data is input to the calculator 626Y.

  The output value from the capacitive liquid level sensor 410Y is temporarily stored in the memory 611Y. The output from the memory 611Y is input to the calculator 621Y. The calculator 621Y calculates the liquid level based on the concentration data and a lookup table (LUT) representing the relationship between the voltage and the liquid level. The liquid level data is input to the concentration / liquid level control unit 640Y.

  The concentration / liquid level control unit 640Y receives data from the calculator 621Y and the calculator 626Y. The concentration / liquid level control unit 640Y refers to the RAM 650Y, and according to these data, the motor control unit 660Y that operates the high concentration developer supply pump 513Y, the motor control unit 670Y that operates the carrier liquid supply pump 523Y, and the image A control command is transmitted to the image forming unit 680 responsible for formation.

In FIG. 19, first, measurement is performed by the temperature sensor 490Y (step S41), and the developer temperature is calculated from the sensor output voltage based on a look-up table (LUT) representing the relationship between voltage and temperature (step S42). Next, measurement is performed by the density sensor 460Y (step S43), and the developer density is determined from the temperature obtained in step S42 and the sensor output voltage obtained in step S43 based on the voltage, temperature and density LUT representing the relationship between density. Calculate (step S44).
Subsequently, measurement is performed by the electrostatic capacitance type liquid level sensor 410Y (step S45), and the LUT representing the relationship between voltage, concentration and liquid level is obtained from the concentration value obtained in step S44 and the output voltage obtained in step S45. Based on this, the liquid level is calculated (step S46). Finally, the necessary replenishment amount is calculated in the concentration / liquid level control unit from the concentration value obtained in step S44 and the liquid level value obtained in step S46, and the input to the motor control unit is determined (step S47). The processing in the concentration / liquid level control unit can be the same as in the first embodiment.

  According to the fourth embodiment as described above, the liquid level calculation unit calculates the liquid level of the liquid developer stored in the storage unit 401Y by detecting the voltage detected by the concentration sensor 460Y and the temperature detected by the temperature sensor 490Y. Therefore, accurate liquid level information can be obtained without being affected by changes in the concentration and temperature, since it is performed based on the concentration calculated based on the capacitance and the capacitance detected by the capacitive liquid level sensor 410Y. Is possible.

10Y, 10M, 10C, 10K ... photoreceptor, 11Y, 11M, 11C, 11K ... corona charger, 12Y, 12M, 12C, 12K ... exposure unit, 13Y, 13Y '... photoreceptor squeeze Roller, 14Y, 14Y '... photosensitive squeeze roller cleaning blade, 16Y ... elastic roller, 17Y ... elastic roller cleaning blade, 18Y ... photosensitive member cleaning blade, 20Y, 20M, 20C, 20K ... Developing roller, 21Y ... developing roller cleaning blade, 22Y ... toner compression corona generator, 30Y, 30M, 30C, 30K ... developing device, 31Y, 31M, 31C, 31K ... developer container, 32Y, 32M, 32C, 32K ... Anilox roller, 33Y ... Regulating blade, 34Y ... auger (feed roller), 40 ... transfer belt, 41 ... belt drive roller, 42 ... tension roller, 46 ... transfer belt cleaning blade, 50Y, 50M, 50C, 50K: primary transfer part, 51Y, 51M, 51C, 51K ... primary transfer backup roller, 60 ... secondary transfer unit, 61 ... secondary transfer roller, 62 ... secondary transfer roller cleaning Blade, 90 ... fixing unit, 280 ... developer storage base, 281 ... recovery auger, 285 ... recycled developer recovery tube, 310Y ... supply storage section, 320Y ... recovery storage section , 321Y: Recovery auger, 330Y: Partition, 370Y: Liquid developer supply pipe, 371Y: Liquid developer times Pipe, 375Y ... Liquid developer supply pump, 400Y ... Density adjustment tank, 401Y ... Container, 402Y ... Lid, 405Y ... Motor, 406Y ... Shaft, 407Y ..Agitating blade, 410Y ... Capacitive liquid level sensor, 411Y ... Mounting base, 412Y ... Mounting base, 421Y ... First sensor electrode, 422Y ... Second sensor electrode 423Y ... 1st spacer (regulating member), 424Y ... 2nd spacer (regulating member), 450Y ... fixed member, 451Y ... support member, 460Y ... concentration sensor, 490Y ... Temperature sensor, 510Y: High concentration developer tank, 511Y: High concentration developer supply pipe, 513Y: High concentration developer supply pump, 520Y: Carrier liquid tank, 5 21Y: Carrier liquid supply pipe, 523Y: Carrier liquid supply pump, 530Y: Buffer tank, 531Y: Recycled developer supply pipe, 533Y: Recycled developer supply pump, 611Y, 616Y, 619Y ... Memory, 621Y, 626Y, 629Y ... Arithmetic unit, 631Y, 636Y, 639Y ... LUT (Lookup Table), 640Y ... Concentration / Liquid Level Control Unit, 650Y ... RAM (Random Access) Memory), 660Y ... motor control unit, 670Y ... motor control unit, 680 ... image forming unit,

Claims (7)

An accommodating portion for accommodating a liquid developer including toner and a carrier;
A capacitance detection unit that detects a capacitance by having a first electrode provided in the storage unit, and a second electrode provided in the storage unit and facing the first electrode via a liquid developer. When,
A density detector that is disposed in the container and detects the toner density of the liquid developer;
A liquid level for calculating the liquid level of the liquid developer stored in the storage unit based on the capacitance detected by the capacitance detection unit and the toner concentration detected by the concentration detection unit. A calculation unit;
A developing device comprising: A temperature detection unit for detecting the temperature of the liquid developer stored in the storage unit;
The developing device according to claim 1, wherein the liquid level calculation unit calculates the liquid level of the liquid developer stored in the storage unit based on the temperature detected by the temperature detection unit. The developing device according to claim 2, wherein the liquid level calculation unit corrects the toner concentration detected by the concentration detection unit based on the temperature detected by the temperature detection unit. A latent image carrier on which a latent image is formed;
An exposure unit that exposes the latent image carrier to form the latent image;
A storage container for storing a liquid developer including toner and a carrier; a first electrode provided in the storage portion; and a second electrode provided in the storage portion and opposed to the first electrode via the liquid developer. A capacitance detection unit that detects a capacitance; and a concentration detection unit that is disposed in the housing unit and detects a toner concentration of the liquid developer; a developer storage unit that stores the liquid developer;
A developer carrying member for carrying the liquid developer supplied from the developer reservoir, and a supply member for supplying the liquid developer to the developer carrying member, and the latent image formed on the latent image carrier. A developing section for developing the image;
Liquid level calculation that calculates the liquid level of the liquid developer stored in the storage unit based on the capacitance detected by the capacitance detection unit and the toner concentration detected by the concentration detection unit. And an image forming apparatus. A temperature detection unit that detects a temperature of the liquid developer stored in the storage unit;
The image forming apparatus according to claim 4, wherein the liquid level calculation unit calculates the liquid level of the liquid developer stored in the storage unit based on the temperature detected by the temperature detection unit. The image forming apparatus according to claim 5, wherein the liquid level calculation unit corrects the toner concentration detected by the concentration detection unit based on the temperature detected by the temperature detection unit. A developer storage tank for storing a liquid developer having a first toner concentration;
A carrier liquid storage tank for storing the carrier liquid;
The liquid developer or carrier liquid having the first toner concentration stored in the developer storage tank is supplied, and the toner concentration of the liquid developer stored in the storage portion of the developer storage portion is changed to the first concentration. A control unit that controls the second toner concentration to be lower than the toner concentration;
An image forming apparatus according to any one of claims 4 to 6.

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