JP5287678B2 - Developer density adjusting device, developer density adjusting method, and image forming apparatus - Google Patents

Description

  The present invention relates to a developer concentration adjusting device for adjusting the concentration of a liquid developer used for image formation, a developer concentration adjusting method, and an image forming apparatus using them.

  2. Description of the Related Art An electrophotographic image forming apparatus that forms an electrostatic latent image on a photoconductor (image carrier), adheres toner to the image, and transfers and fixes the image on paper or the like is widely used. In particular, in an image forming apparatus that requires higher image quality and higher resolution, such as an office printer for large-scale printing and an on-demand printing apparatus, a wet process using a liquid developer that has a small toner particle diameter and is less likely to cause toner image disturbance. Development methods are being used.

  In recent years, an image using a high-viscosity and high-concentration liquid developer, which is composed by dispersing toner as a solid content composed of a resin and a pigment in an insulating liquid “carrier liquid” such as silicone oil at a high concentration. Forming devices have been proposed.

  When developing using this liquid developer, a thin layer of developer is formed on a developer carrier such as a developing roller, and the thinned developer is brought into contact with the photoreceptor. It is common to develop. However, even after the latent image on the photoconductor is developed, the liquid developer remains on the developing roller, which adversely affects the next development.

  In order to cope with such a problem, a technique for cleaning and collecting the developer on the developing roller remaining after the development has been developed. In addition, a technique has been proposed in which the developer can be effectively used by reusing the collected developer.

  However, the developer used for development is a high-concentration developer. However, after developing the latent image on the image carrier, a considerable amount of toner is consumed, and the density of the residual developer changes considerably. There are many. If this is poured into the developer tank as it is, the developer itself in the developer tank changes in density, making it difficult to ensure a predetermined density.

  In order to deal with these problems, before pouring the collected developer into the developer tank, a developer for adjusting the concentration (such as a high-concentration developer or a low-concentration developer) is replenished to collect the collected developer. Techniques for making adjustments have been proposed.

  However, in order to obtain a developer having a desired density by adjusting the density as described above, it is necessary to simply measure the density of the developer while making the adjustment.

  As a simple method for measuring the developer concentration, a technique for calculating the developer concentration by utilizing the fact that the light transmittance of the developer changes depending on the concentration has been proposed.

  However, the above-mentioned method has a problem in a high-concentration developer that is exclusively used in recent years. That is, as the developer concentration increases, the light transmittance decreases and becomes saturated, so that the sensitivity decreases and the change in transmittance with respect to the density change decreases.

  A technique using viscosity has been proposed as a method for simply and efficiently measuring the concentration of a high-concentration developer. The viscosity changes relatively large and responds to changes in concentration in the high concentration region. In addition, as a method for measuring the viscosity of such a developer, a characteristic value that can be measured relatively easily, such as rotational torque during stirring of the developer, can be used as a substitute characteristic of viscosity (for example, patents). Reference 1 and 2).

  In Patent Document 1, an opening is provided in the concentration adjustment tank, and a stirring load is measured while overflowing during stirring, thereby maintaining a constant developer amount while supplying a replenisher for concentration adjustment. Techniques for ensuring accuracy are presented.

  Further, in Patent Document 2, a technique of performing agitation without a developer before density adjustment and correcting measurement of the agitation load on the density adjustment developer based on the load current to ensure measurement accuracy. Is presented.

JP 2008-209716 A JP 2009-3346 A

  As described in Patent Documents 1 and 2, as a method for measuring the viscosity of the developer, a characteristic value that can be measured relatively easily, such as the rotational torque during stirring of the developer, should be used as a substitute characteristic of the viscosity. Can do.

  However, the liquid developer naturally adheres to the stirring member used for stirring. In Patent Documents 1 and 2, the liquid developer whose density has been adjusted is discharged after completion of the density adjustment, but there is no particular description regarding the handling of the stirring member to which the developer has adhered.

  In particular, when a highly volatile carrier liquid is used, if the liquid developer is discharged in an empty state, the developer with high viscosity may remain on the surface of the stirring member, and the toner may be fixed. .

  When toner adheres to the stirring member for measuring the stirring load, the frictional resistance between the stirring member and the liquid developer changes, which affects the viscosity measurement of the liquid developer, and as a result, correct density adjustment is performed. There is a possibility that a malfunction that cannot be performed occurs.

  It is possible that the concentration adjusting tank provided with the stirring member for adjusting the concentration, such as during a weekend or a long holiday, can be left for a long time with the liquid developer empty.

  The present invention has been made in view of the above technical problems.

  The object of the present invention is to dry the residual developer on the stirring member while using a characteristic value that can be measured relatively easily, such as the stirring load of the liquid developer by the stirring member, as a substitute characteristic of the viscosity, that is, the developer concentration. It is an object to provide a developer concentration adjusting device, a developer concentration adjusting method, and an image forming apparatus using them, which can prevent the occurrence of a malfunction in toner concentration detection due to sticking or the like and enable accurate density adjustment.

  In order to solve the above problems, the present invention has the following features.

1. In order to adjust the toner concentration of the liquid developer containing the toner and the carrier liquid to a predetermined concentration,
A density adjusting tank for storing a liquid developer for density adjustment;
An agitation member for agitating the liquid developer contained in the concentration adjustment tank;
Load detecting means for detecting a stirring load when the liquid developer is stirred by the stirring member;
Replenishment means for replenishing the density adjustment tank with a replenishment developer for density adjustment;
Control means for controlling replenishment of the replenishment developer by the replenishment means based on the stirring load detected by the load detection means, and adjusting the concentration of the liquid developer,
The control means includes
In order to remove the toner remaining on the stirring member in the density adjusting tank before the liquid developer is contained in the empty density adjusting tank and density adjustment is performed, the stirring member is removed. A developer concentration adjusting apparatus, wherein the developer concentration is controlled to be cleaned by being stirred under a stirring condition different from that when performing the density adjustment while being immersed in a liquid developer for cleaning.

2. The cleaning liquid developer used at the time of cleaning the stirring member by the control means,
2. The developer concentration adjusting apparatus according to item 1, wherein the developer concentration adjusting device is a liquid developer having a concentration lower than that of the carrier liquid or the predetermined concentration and lower than a concentration of the concentration adjusting liquid developer.

3. The replenishing means is
A first supply means for supplying a first supply developer having a concentration higher than the predetermined concentration to the concentration adjustment tank, and a second supply developer having a concentration lower than the predetermined concentration is supplied to the density adjustment tank. A second supply means for
3. The developer concentration adjustment according to item 2, wherein the cleaning liquid developer is a second replenishment developer or a mixed developer of a second replenishment developer and a liquid developer for concentration adjustment. apparatus.

4). When cleaning the stirring member by the control means,
4. The developer concentration adjusting apparatus according to claim 1, wherein the agitation member is driven at a higher speed than when the agitation member is agitated to detect the agitation load.

5. When cleaning the stirring member by the control means,
The developer concentration adjusting apparatus according to any one of 1 to 4, wherein the stirring member is driven while changing a speed.

6). An ultrasonic vibration member in the concentration adjustment tank;
When cleaning the stirring member by the control means,
6. The developer concentration adjusting apparatus according to any one of 1 to 5, wherein vibration by the ultrasonic vibration member is added.

7). The control means includes
Measuring the time after the liquid developer is discharged from the density adjusting tank and becoming empty, and determining whether to clean the stirring member based on the measured time. 7. The developer concentration adjusting apparatus according to any one of 1 to 6.

8). The concentration adjustment tank is a cylindrical container,
An opening that overflows when the contained liquid developer reaches a certain liquid level,
The load detecting means includes
The liquid developer in the concentration adjusting tank is stirred by the stirring member and overflows from the opening, or after the stirring load is detected, and the stirring load is detected. The developer concentration adjusting apparatus according to claim 1.

9. In order to adjust the toner concentration of the liquid developer containing the toner and the carrier liquid to a predetermined concentration,
A developer storage step of storing a liquid developer for concentration adjustment in the concentration adjustment tank;
A load detection step of detecting a stirring load while stirring the liquid developer contained in the concentration adjustment tank by a stirring member;
A replenishment step of replenishing the density adjusting tank with a replenishment developer for density adjustment;
A control step of controlling execution of the replenishment step based on the stirring load detected in the load detection step and adjusting the concentration of the liquid developer,
In the control step,
In order to remove the toner remaining on the stirring member in the density adjusting tank before the liquid developer is contained in the empty density adjusting tank and density adjustment is performed, the stirring member is removed. A developer concentration adjusting method, wherein the developer is controlled to be cleaned by being stirred under a stirring condition different from that when performing the concentration adjustment while immersed in a cleaning liquid developer.

10. The cleaning liquid developer used at the time of cleaning the stirring member in the control step,
10. The developer concentration adjusting method as described in 9 above, wherein the developer concentration is lower than the concentration of the carrier liquid or the predetermined concentration and lower than the concentration of the liquid developer for concentration adjustment.

11. The replenishment step includes
A first replenishment step of replenishing the density adjustment tank with a first replenishment developer having a higher density than the predetermined density; and a second replenishment developer having a density lower than the predetermined density is replenished to the density adjustment tank. And a second replenishment step
11. The developer concentration adjustment according to item 10, wherein the cleaning liquid developer is a second replenishment developer or a mixed developer of a second replenishment developer and a liquid developer for concentration adjustment. Method.

12 When cleaning the stirring member in the control step,
The developer concentration adjusting method according to any one of 9 to 11, wherein the stirring member is driven at a higher speed than when stirring to detect the stirring load.

13. When cleaning the stirring member in the control step,
The developer concentration adjusting method according to any one of 9 to 12, wherein the stirring member is driven while changing a speed.

14 When cleaning the stirring member in the control step,
14. The developer concentration adjusting method according to any one of 9 to 13, wherein vibration by an ultrasonic vibration member is added.

15. When cleaning the stirring member in the control step,
Measuring the time after the liquid developer is discharged from the density adjusting tank and becoming empty, and determining whether to clean the stirring member based on the measured time. 15. The developer concentration adjusting method according to any one of 9 to 14.

16. In the developer containing step,
When the liquid developer accommodated in the concentration adjustment tank having a cylindrical shape is in a cylindrical shape and reaches a certain liquid level, it overflows from the opening,
In the load detection step,
Any of 9 to 15 above, wherein the liquid developer in the concentration adjusting tank is stirred by the stirring member and overflows from the opening or after the stirring load is detected. The developer concentration adjusting method according to claim 1.

17. An image carrier that forms a latent image on the surface;
A liquid developing device that develops a latent image on the surface of the image carrier with a liquid developer and forms a toner image;
The developer concentration adjusting apparatus according to any one of 1 to 8 above,
An image forming apparatus, wherein the liquid developer adjusted to a predetermined developer concentration by the developer concentration adjusting device is supplied to the liquid developing device.

18. 18. The image forming apparatus as described in 17 above, wherein when the power of the image forming apparatus is turned on or when driving is started, the control means of the developer concentration adjusting device controls to clean the stirring member.

  According to the developer concentration adjusting device, the developer concentration adjusting method, and the image forming apparatus using them according to the present invention, the developer for cleaning the stirring member is supplied to the concentration adjusting tank at the start of density adjustment, and the density adjustment is performed. In the tank, the stirring member is immersed in a cleaning developer and a stirring operation is performed to clean the stirring member. As a result, it is possible to prevent the occurrence of abnormal toner density detection due to dry fixing of the residual developer to the stirring member, and to enable accurate density adjustment.

1 is a cross-sectional view illustrating a schematic configuration example of an image forming apparatus 10 according to the present invention. FIG. 2 is a layout diagram illustrating a schematic configuration example of a liquid developing device 4 in FIG. 1. FIG. 3 is a layout diagram illustrating a schematic configuration example of a developer concentration adjusting device 60 in FIG. 2. FIG. 4 is an apparatus configuration diagram for explaining an operation of a developer concentration measuring unit 50 in FIG. 3. It is a graph which shows the relationship ((a) normal rotation, (b) high speed rotation, (c) speed variable rotation) of cleaning time and rotational speed as stirring conditions at the time of cleaning of a stirring member. It is a flowchart which shows the process example of the density adjustment method of a developer density adjustment apparatus. It is a flowchart which shows the example of a process sequence of the cleaning process of the stirring member in FIG.

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

  A liquid developing device using a liquid developer is used in an image forming apparatus such as a copying machine, a simple printing machine, or a printer. In general, an electrophotographic image forming process is commonly used for these. First, the electrophotographic wet image forming apparatus will be described with reference to FIG. 1, and a liquid developing apparatus (see FIG. 2) for reusing the collected developer and the developer concentration adjusting apparatus used there. The configuration and functional operation will be described (see FIG. 3).

(Configuration and functional operation of image forming apparatus)
A configuration example of the image forming apparatus according to the present exemplary embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating a schematic configuration example of a wet image forming apparatus.

  In FIG. 1, reference numeral 1 denotes a photosensitive drum, which functions as an image carrier. The image forming apparatus 10 is centered on the photosensitive drum 1 and has a charging device 2 for uniformly charging the surface of the photosensitive drum 1, and an LED or laser beam on the charged photosensitive drum 1. , An exposure device 3 for forming an electrostatic latent image, a liquid developing device 4 for developing the electrostatic latent image using a liquid developer, and a transfer device 5 for transferring the developed toner image to a transfer material 7. And a cleaning device 6 for removing the liquid developer remaining on the surface of the photosensitive drum after transfer.

  In some cases, before and after the liquid developing device 4, a device for applying or collecting a part of the liquid developer in advance is provided. The transfer material 7 may be a recording material such as recording paper as it is, or may be configured such that the transfer material 7 is transferred again to the recording material using an intermediate transfer belt or the like.

  In general, the liquid developing device 4 bears a thin layer of a liquid developer on its surface and abuts against a developing roller 41 and a developing roller 41 that develop a latent image on the photosensitive drum 1 that is an image carrier. A transport roller 42 for transferring the liquid developer whose liquid amount is adjusted to the surface thereof, and a supply roller 43 that contacts the transport roller 42 and supplies the liquid developer 8 in the developer tank 44 to the surface thereof. .

  In FIG. 1, only one liquid developing device 4 is disposed, but a plurality of liquid developing devices 4 may be disposed for color image formation. The color development method, the presence / absence of intermediate transfer, and the like may be set arbitrarily, and an arbitrary arrangement according to the method can be adopted.

  The photosensitive drum 1 rotates in the direction of arrow A shown in FIG. 1, and the charging device 2 charges the surface of the rotating photosensitive drum 1 to about several hundred volts by corona discharge or the like. On the downstream side of the charging device 2 in the rotation direction of the photosensitive drum, an electrostatic latent image whose surface potential is lowered to about 100 V or less is formed by the laser beam emitted from the exposure device 3.

  A liquid developing device 4 is disposed further downstream of the exposure device 3, and the electrostatic latent image formed on the photosensitive drum 1 is developed using the liquid developer 8.

  In the liquid developing device 4, a liquid developer 8 in which toner is dispersed in an insulating solvent (hereinafter also referred to as carrier liquid) is accommodated in a developer tank 44, and the surface of the conveying roller 42 is supplied by a supply roller 43. Is supplied with a liquid developer 8.

  The conveying roller 42 conveys a thin layer of the liquid developer 8 and transfers it to the developing roller 41. A thin layer of the liquid developer 8 is carried on the developing roller 41. Further, due to the potential difference between the developing roller 41 and the electrostatic latent image on the photosensitive drum 1, the toner particles in the thin layer of the liquid developer 8 carried on the developing roller 41 become an electrostatic latent image on the photosensitive drum 1. Moving, the electrostatic latent image is developed.

  In the transfer device 5, the developed toner image on the photosensitive drum 1 is transferred to the transfer material 7 by charging the transfer material 7 conveyed at the same speed as the peripheral speed of the photosensitive drum 1 or applying a voltage. Transcribed above.

  A cleaning device 6 for removing the liquid developer 8 remaining on the surface of the photosensitive drum 1 is disposed on the downstream side of the transfer device 5. The cleaning device 6 removes the liquid developer 8 remaining on the photosensitive drum 1.

  If the transfer material 7 onto which the toner image has been transferred by the transfer device 5 is a recording material, it is conveyed to a fixing device (not shown), and is discharged after heating and fixing. If the transfer material 7 is an intermediate transfer member such as an intermediate transfer belt, then the toner image is re-transferred to the recording material, and the recording material onto which the toner image has been transferred is also conveyed to the fixing device, where it is heated and fixed. Discharged.

(Developer composition)
The liquid developer 8 used for development will be described. In the liquid developer 8, colored toner particles are dispersed at a high concentration in a carrier liquid as a solvent. In addition, additives such as a dispersant and a charge control agent may be appropriately selected and added to the liquid developer 8.

  As the carrier liquid, an insulating solvent is used. The toner particles are mainly composed of a resin and a pigment or dye for coloring. The resin has a function of uniformly dispersing pigments and dyes in the resin and a function as a binder when being fixed to the recording material.

  The volume average particle diameter of the toner is suitably in the range of 0.1 μm or more and 5 μm or less. When the average particle diameter of the toner is less than 0.1 μm, the developability is greatly lowered. On the other hand, when the average particle diameter exceeds 5 μm, the quality of the image is deteriorated.

  The ratio of the toner particle mass to the liquid developer mass is suitably about 10 to 40%. If it is less than 10%, toner particles are liable to settle, and there is a problem with the stability over time during long-term storage. Further, in order to obtain a required image density, it is necessary to supply a large amount of developer, the carrier liquid adhering to the paper increases, and it must be dried at the time of fixing, and steam is generated, resulting in environmental problems. If it exceeds 40%, the viscosity of the liquid developer becomes too high, making it difficult to manufacture and handle.

(Configuration and operation of developing device)
FIG. 2 shows a schematic configuration example of the liquid developing device 4 in FIG. The configuration and operation of the liquid developing device 4 will be described with reference to FIG.

  The developer tank 44 contains the liquid developer 8 described above.

  The supply roller 43 is disposed so as to be immersed in the liquid developer 8 in the developer tank 44, rotates in the direction of arrow D, and draws the liquid developer 8 from the developer tank 44. The high-viscosity liquid developer 8 is conveyed while adhering to the surface of the supply roller 43 due to its adhesive force.

  As shown in the figure, the regulating member 45 is disposed so as to face the supply roller 43 and abut against the rotation in the counter direction, and regulates the amount of developer that adheres to the surface of the supply roller 43 and is conveyed. Is. As a result, an excessive amount of developer is peeled off, and a thin developer layer is formed on the surface of the supply roller 43 and is conveyed toward the next conveying roller 42.

  As the conveying roller 42, a rubber roller is generally used. The conveying roller 42 is disposed to face the supply roller 43 and rotates in the direction of arrow C while contacting. At this nip portion, the developer thin layer formed on the surface of the supply roller 43 is copied onto the surface of the conveying roller 42 and conveyed toward the developing roller 41.

  As the developing roller 41, a low hardness rubber roller is used. The developing roller 41 is disposed to face the conveying roller 42 and rotates in the direction of arrow B while contacting. The developer thin layer transported to the surface of the transport roller 42 at this nip is scraped off by the developing roller 41, and the developer thin layer is carried and transported to the surface of the developing roller 41. Therefore, the developing roller 41 functions as a developer carrier.

  Here, the transport roller 42 forms a developer thin layer and delivers it to the developer carrier, but the supply roller 43 may have the function. That is, it is possible to adopt a method of transferring the developer directly from the supply roller 43 to the developing roller 41.

  The developing roller 41 also rotates in contact with the photosensitive drum 1 that is an image carrier, and the developer thin layer conveyed to the nip portion with the photosensitive drum 1, that is, the developing region, is on the photosensitive drum 1. The latent image will be developed.

  However, a thin layer of developer remains on the surface of the developing roller 41 even after the latent image on the photosensitive drum 1 is developed. If the remaining developer is transported to the development area again as it is, it adversely affects the next development. The removing member 46 is a blade for cleaning, and removes the remaining developer.

(Configuration for developer recovery and reuse)
FIG. 2 also shows a schematic configuration for collecting and reusing the residual developer removed in the liquid developing device 4 in FIG. A configuration relating to recovery and reuse of the liquid developer in the liquid developing device 4 will be described with reference to FIG.

  As described above, the thin developer layer remaining on the developing roller 41 is removed by the removing member 46. However, since the collected developer accumulates there, a storage container is required even if it is collected and discarded. Therefore, in the present embodiment, the recovered developer is reused so that such a container is not necessary and the developer can be used effectively.

  The developer scraped off from the surface of the developing roller 41 by the removing member 46 is temporarily stored in the collected developer tank 53 as the collected developer.

  The recovered developer once stored in the recovered developer tank 53 is sent to the developer concentration adjusting device 60 to be adjusted to a predetermined concentration and reused.

  The recovered developer adjusted to a predetermined concentration by the developer concentration adjusting device 60 is supplied to the developer tank 44 of the liquid developing device 4 and reused. Alternatively, the toner may be temporarily stored in a supply tank (not shown) and then supplied to the developer tank 44.

<Configuration of developer concentration adjusting device>
The developer concentration adjusting device 60 shown in FIG. 2 is also schematically shown in FIG. A configuration relating to the concentration adjustment of the collected developer in the developer concentration adjusting device 60 will be described with reference to FIGS.

  The developer concentration adjusting device 60 includes a developer concentration measuring unit 50, a first supply developer tank 54 and a first supply developer supplying unit 54a that function as a first supply unit, and a second supply unit. A second replenishment developer tank 55 and a second replenishment developer supply unit 55a functioning are included. These function as supply means.

  The first supply developer tank 54 contains, for example, a liquid developer having a concentration higher than a predetermined concentration as the first supply developer, and the developer concentration is measured by the first supply developer supply unit 54a. Part 50 is replenished.

  The second replenishment developer tank 55 stores, for example, a liquid developer having a concentration lower than a predetermined concentration (including the case of only the carrier liquid) as the second replenishment developer. The developer concentration measuring unit 50 is replenished by the developer supply unit 55a.

  In the developer concentration adjusting device 60, the collected developer sent for density adjustment is sent to the developer concentration measuring unit 50 as a density adjusting developer.

  The developer concentration measuring unit 50 measures the concentration of the developer for adjusting the concentration (actually, the motor current value as a stirring load corresponding to the viscosity). The first replenishment developer or the second replenishment developer is replenished according to a comparison result with a predetermined density (predetermined current value, that is, target current value). That is, when the concentration is lower than the predetermined concentration, a high concentration developer (first supply developer) is supplied, or when the concentration is high, a low concentration developer (second supply developer) is supplied. .

  In the developer concentration adjusting device 60, the concentration measurement by the developer concentration measuring unit 50 and the supply of the replenishment developer are continued until the concentration adjusting developer reaches a predetermined concentration.

  When the density adjusting developer reaches a predetermined density, the density adjustment is finished, and the density adjusted developer whose density has been adjusted is supplied from the developer density adjusting device 60 to the developer tank 44 of the liquid developing device 4. A detailed processing procedure of density adjustment in the developer density adjusting device 60 will be described later.

<Configuration of developer concentration measuring section>
As for the developer concentration measuring unit 50 shown in FIG. 2, a schematic configuration example is also shown in FIG. A configuration relating to the concentration measurement of the collected developer in the developer concentration measuring unit 50 will be described with reference to FIGS.

  The developer concentration measuring unit 50 includes a density adjusting tank 51, a discharged developer tank 52, a control unit 61, a stirring member 62, a driving device 63, and a load detecting device 64.

  The density adjusting tank 51 is a tank for storing a density adjusting developer and adjusting the density. The agitation member 62 is driven by the driving device 63 to agitate the concentration adjusting developer in the concentration adjusting tank 51 and the load is detected by the load detecting device 64 to measure the density. FIG. 4 illustrates their configuration.

  The description will be continued with reference to FIG.

  In the present embodiment, the concentration adjustment tank 51 is a cylindrical container and has an opening 51a. The opening 51a has a function of maintaining a constant amount of the concentration adjusting developer by increasing the amount of the stored density adjusting developer and overflowing when the liquid level exceeds the position of the opening. have.

  The discharged developer tank 52 is a tank that receives and accommodates the density adjusting developer overflowing in this manner. The accumulated developer may be discarded, but it is desirable that the developer be returned to the density adjusting developer again at the next density adjustment and reused efficiently. Further, it may be configured to return directly to the collected developer tank 53 without the discharged developer tank 52.

  The stirring member 62 is, for example, a stirring blade, and is installed in the density adjustment tank 51 and is rotationally driven by the driving device 63 to stir the stored density adjusting developer. The driving device 63 is, for example, a motor, and rotates a stirring blade as the stirring member 62 under a predetermined condition. That is, the stirring member 62 and the driving device 63 function as stirring means.

  The load detection device 64 is a device that detects a load in driving the stirring member 62 by the drive device 63, and obtains a detection value corresponding to the viscosity of the liquid developer. Viscosity depends on concentration. That is, the load detection device 64 functions as load detection means.

  As the load detection device 64, an ammeter that measures a current value required for the rotation of the motor under a predetermined condition is used as a load for the rotation of the rotating blades by the motor. The stirring member 62 is not limited to a rotating stirring blade. The drive device 63 and the load detection device 64 may be set according to the form of the stirring member 62.

  The controller 61 controls the operation of these components to obtain the density of the density adjusting developer or a current value corresponding to the density. Further, based on a comparison with a predetermined concentration (or a corresponding target current value), the replenishment operation of the first replenishing means or the second replenishing means for adjusting the concentration is controlled. That is, the control unit 61 functions as a control unit.

  The control unit 61 as a control unit also controls the overall processing of the liquid developer from the storage of the density adjusting developer in the density adjusting tank 51 to the discharge of the density adjusted developer to the developer tank 44.

(Density measuring mechanism of developer density measuring unit)
The configuration of the developer concentration measuring unit 50 described above is for calculating the density by detecting the motor current value as a load when the developer for density adjustment is stirred using the stirring means. It is a configuration. This is based on the fact that the viscosity varies depending on the concentration of the density adjusting developer, and the load for stirring varies depending on the viscosity of the developer.

  Hereinafter, a conventional developer concentration measuring method different from the present embodiment will be described.

  As described above, in the liquid developer, toner is dispersed in the carrier liquid. The concentration of the liquid developer is represented by the concentration of toner in the developer. As a method for measuring this concentration, conventionally, measurement using light transmittance has been often performed.

  However, as described above, in recent years, a high-concentration liquid developer is exclusively used. For a high-concentration developer, the light transmittance is saturated to a low value, and sufficient measurement sensitivity cannot be obtained.

  Instead, it has been considered to determine the concentration by measuring the viscosity. As the developer concentration changes, the viscosity also changes. In particular, the amount of change in viscosity is large in a high concentration region, and sufficient measurement sensitivity can be obtained.

  Further, when the viscosity of the developer changes, the load required for stirring it also varies. This can be used to measure viscosity and further concentration from the agitation load. This embodiment also employs this method.

  As a stirring load, it is easy to measure the current value of a motor used for driving a stirring blade or the like. What is necessary is just to measure the electric current value required in order to make it rotate with a predetermined | prescribed rotation speed with an ammeter.

<Liquid level control of developer for density adjustment>
However, in order to determine the viscosity from the load of stirring, the conditions during stirring must be constant. If the stirring blades are rotated as well as the conditions of the apparatus, it is necessary to control the rotation conditions and further the amount of developer to be stirred.

  In the present embodiment, in order to make the developer amount to be measured constant, an opening 51a is provided in the density adjustment tank 51 to overflow. In actuality, when agitated, the liquid surface becomes a mortar shape, and depending on the viscosity, it overflows or the amount of liquid in the state after it varies.

  As can be seen with reference to FIG. 4, the developer liquid moves outward due to the centrifugal force due to the rotation of the stirring blades, and the liquid level 81 has a large mortar shape.

  Therefore, if there is the opening 51a, the upper limit of the liquid level height at the outermost part is restricted, so that the liquid amount changes depending on the developer viscosity.

  In the present embodiment (see FIG. 4), the idea that the amount of liquid at the time of stirring is always controlled to be constant regardless of the viscosity is not taken. Instead, it was assumed that the developer of the same viscosity was configured so that the amount of liquid during stirring was constant. In the present embodiment (see FIG. 4), if the developer has the same viscosity, the same mortar-shaped liquid surface state is realized by regulating the liquid surface by the opening 51a, and the same liquid amount is achieved.

  Of course, if the developer has a different viscosity, the amount of liquid will vary, but depending on the respective viscosity, the predetermined liquid level, that is, the predetermined liquid amount is achieved, so the load of stirring according to the liquid amount and viscosity can be handled. Can be made.

  It is not necessary to control the liquid amount each time for measuring the viscosity, and the opening 51a automatically performs the necessary control. Even when developers having different concentrations are replenished during the measurement, the liquid amount control is automatically performed according to the change in the viscosity.

<Measurement of current value as stirring load>
As described above, as the stirring load, the current value of the motor 63 used for driving the stirring blade 62 and the like is measured. What is necessary is just to measure the electric current value at that time with the ammeter 64 by rotating the stirring blade at a predetermined rotational speed.

  A motor current value as an agitation load for a developer having a predetermined density is acquired in advance and set as a target current value. The current value measured during the stirring of the density adjusting developer is compared with the target current value held, and control is performed so that the first supply developer or the second supply developer is supplied from the magnitude relationship. The unit 61 may be controlled.

  Alternatively, an allowable range is added to the target current value to obtain a target range, and if it is within that range, the density adjustment is terminated, or the first supply developer or the second supply developer depending on whether it exceeds or falls below the target range You may control to perform replenishment.

(Prevents drying and sticking of developer on stirring member)
As described above, the developer concentration adjusting apparatus according to the present embodiment calculates the developer viscosity, that is, the concentration by detecting the agitation load when the concentration adjusting developer is agitated using the agitating member. It is the structure to do.

  Therefore, it is necessary that the stirring load accurately corresponds to the viscosity. Therefore, as described above, it is desirable to adopt a configuration in which the developer amount to be measured is constant. It is also desirable to manage other environmental conditions (for example, the temperature of the liquid developer).

  However, when adopting a configuration in which the load and viscosity at the time of stirring using the stirring member are made to correspond, the following points should be considered. That is, of course, the liquid developer adheres to the stirring member 62 used for stirring.

  After completion of the density adjustment, the liquid developer whose density has been adjusted is discharged from the density adjustment tank 51 to the developer tank 44 for use in development. Then, depending on the case, the liquid developer may be left empty for a long time in the concentration adjustment tank 51 provided with the stirring member 62 for concentration adjustment, such as during a weekend or a long holiday.

  In particular, when a highly volatile carrier liquid is used, if the surface of the stirring member 62 is dried in an empty state where the liquid developer is discharged, a highly viscous developer remains on the surface of the stirring member, and the toner is fixed. Etc. may occur. Even if a non-volatile carrier liquid is used, the liquid may drip and a high-viscosity developer may remain on the surface of the agitating member, causing toner sticking and the like.

  When toner adheres to the stirring member for measuring the stirring load, the frictional resistance between the stirring member and the liquid developer changes, which affects the viscosity measurement of the liquid developer, and as a result, correct density adjustment is performed. There is a possibility that a malfunction that cannot be performed occurs.

  In order to prevent the toner from sticking to the stirring member due to such drying, the following control is performed in this embodiment.

<Adhesive developer cleaning mechanism on stirring member>
The main point is that the developer for cleaning the stirring member is supplied to the density adjustment tank 51 at the start of density adjustment under the control of the control unit 61, and the stirring member 62 is immersed in the cleaning developer in the density adjustment tank 51 and stirred. The operation is to clean the stirring member 62.

  That is, the high-viscosity developer or toner remaining on the surface of the stirring member 62 is washed away by stirring in a state where the developer is immersed in a cleaning developer.

  As the cleaning developer, it is preferable to use a liquid developer having a lower concentration than the carrier liquid or the developer adjusted to a predetermined concentration supplied to the developer tank 44. By using a developer having a lower concentration than that at the time of adjusting the concentration, the adhered toner or the like can be efficiently removed.

  When stirring with the stirring member 62 for cleaning, the stirring conditions are changed from those for stirring for concentration adjustment.

  The purpose of adjusting the density is to measure the stirring load, that is, the viscosity of the developer, but the purpose of cleaning is to remove the developer attached to the stirring member 62. Therefore, it is better to increase the driving speed of the stirring member 62 and increase the pressure with which the cleaning developer rubs against the surface of the stirring blade.

  Specifically, the centrifugal force is applied by increasing the rotation speed of the stirring blades from the time of density adjustment, and the attached toner and the like are easily removed. Further, by changing the rotation speed during cleaning, pressure is applied to the stirring blade, and the attached toner and the like are easily removed.

  It is also desirable to install an ultrasonic vibration member in the density adjustment tank 51 and apply ultrasonic vibration via a cleaning developer at the time of cleaning because it is easy to remove attached toner and the like.

<Amount of developer for cleaning>
The amount of the cleaning developer in which the stirring member 62 is immersed is preferably smaller than the amount of the liquid developer for adjusting the density. At the time of concentration adjustment, in order to stabilize the stirring load, the liquid level is sufficiently higher than the position of the stirring member (stirring blade) of the concentration adjusting tank 51 (the amount of liquid in the overflow state). The stirrer blades do not come out of the liquid surface during driving, and the amount of liquid can be removed efficiently.

  Further, the cleaning developer used for cleaning can be used as a developer for density adjustment after being discharged once after cleaning or left in the density adjustment tank 51 as it is. In the case of using a liquid, etc., cleaning with a small amount as much as possible does not become too low in concentration, and concentration adjustment to a predetermined concentration can be performed efficiently.

<Reuse of cleaning developer>
Whether or not the cleaning developer is left as it is in the density adjusting tank 51 and used as a density adjusting developer may be arbitrarily set. The control unit 61 may perform control so that selection is performed in consideration of an efficient one or the like.

  If it is not left in the density adjustment tank 51 as it is, it may be discharged to the discharged developer tank 52 and the like once. In this case as well, it is desirable not to discard and increase the waste liquid, but to reuse it as a replenisher for density adjustment or as a cleaning developer at an appropriate timing.

  When the developer is used as it is as a density adjusting developer, it is possible to omit transport time such as discharging the developer. Also, if the collected developer, etc., whose concentration is to be adjusted is high, the collected developer is directly put into the remaining low-concentration cleaning developer, so that the efficiency of density adjustment can be increased over time. It becomes efficient even from the amount.

  On the other hand, if the collected developer or the like whose density is to be adjusted is low in concentration, if the low-concentration cleaning developer is left as it is, a large amount of high-concentration replenishment developer will be charged, and the efficiency of density adjustment However, this may not be the time or the amount of supplied developer. It is desirable that the cleaning developer is once discharged into the discharged developer tank 52 and reused at an appropriate timing for improving efficiency.

<Processing According to Concentration (Recovery) Developer Concentration>
The density of the collected developer or the like may be estimated from the B / W ratio of the image output so far, or the collected developer tank 53 is provided with a stirring member and stirred. It may be calculated from the load. Of course, the density adjustment operation may be started without estimating the density of the collected developer.

  In addition to the remaining developer on the developing roller, the recovered developer to be reused after adjusting the density may be a remaining surface developer such as an image carrier or may be recovered from any member to which the liquid developer adheres. . However, they all differ in concentration. When these are reused, all of them may be used at once. However, the density adjusting developer, the high-concentration first supply developer, the low-concentration second supply developer, and the like are properly used. Efficient and desirable.

<Cleaning timing of stirring member>
The cleaning may be performed after the concentration adjusting tank 51 is left empty. There is no need to perform cleaning while the concentration is continuously adjusted.

  Specifically, for example, when the power of the image forming apparatus is turned on or when driving is started, the control unit 61 controls the injection of the cleaning developer into the concentration adjustment tank 51 at a predetermined timing, and the stirring member 62 is cleaned. It is driven while being immersed in a developer.

  Further, for example, when the density adjustment is not performed for a certain period of time, that is, when the density adjustment tank is empty, when the density adjustment is started, the cleaning developer is injected into the density adjustment tank 51, The stirring member 62 is driven in the cleaning developer to perform cleaning.

  The fixed time may be set according to the characteristics of the developer. Generally, it is a unit of several hours to several days.

  As a method for detecting that a set fixed time has passed without concentration adjustment, for example, the time counting since the last stop of the stirring load detection operation, the operation of discharging the liquid developer from the concentration adjustment tank It is possible to use a time count from the end of the operation, or any other time count from an appropriate operation timing.

  Since the image forming apparatus is generally set to perform a density adjustment operation at any time during driving, the time counting from when the driving of the image forming apparatus is stopped may be followed.

  An example of a procedure for cleaning the stirring member that determines execution of cleaning based on whether or not a certain amount of time has passed when starting the density adjustment and controls the execution will be described below.

(Density adjustment method processing example)
FIG. 6 is a flowchart showing a processing example of the density adjustment method of the developer density adjustment apparatus. A processing example of the density adjustment method of the developer density adjustment apparatus will be described with reference to FIG.

  When starting the developer concentration adjustment, first, in step S11, the concentration adjusting tank 51 is in a state where the liquid developer is empty. The control unit 61 determines whether to clean the stirring member according to a predetermined processing procedure, and controls the execution of the cleaning.

  FIG. 7 is a flowchart showing a processing procedure example of the stirring member cleaning step (step S11) in FIG. A processing procedure example of the stirring member cleaning step will be described with reference to FIG.

<Example of processing procedure for stirring member cleaning>
In FIG. 7, first, in step S <b> 1, the time after the concentration adjustment tank 51 becomes empty is acquired, and the control unit 61 determines whether or not to clean the stirring member according to a predetermined processing procedure. The determination is based on whether or not the acquired time count result has reached a predetermined time.

  When a certain time has passed in step S1 (step S1: Yes), the process proceeds to step S2, and the execution of cleaning is started. If the predetermined time has not elapsed in step S1 (step S1: No), the cleaning is not performed, and the flow returns to the flow of FIG. 6 to finish the stirring member cleaning step (step S11).

  Next, in step S <b> 2, in order to clean the stirring member 62, the control unit 61 injects a predetermined amount of cleaning developer into the concentration adjustment tank 51 according to a predetermined processing procedure. The cleaning developer is, for example, a carrier liquid prepared as a second supply developer.

  In step S <b> 3, the control unit 61 performs stirring by the stirring member 62 under a predetermined condition, and cleans the stirring member 62. The predetermined condition is, for example, the rotational speed or time of the stirring member (stirring blade), and is set faster than the rotational speed at the time of concentration adjustment.

  In step S <b> 4, the controller 61 discharges the cleaning developer from the density adjustment tank 51. In this case, in order to accommodate the density adjusting developer in the subsequent density adjustment, the toner is once emptied. Of course, as described above, the cleaning developer may be left in the density adjustment tank 51 and used for subsequent density adjustment.

  This completes the cleaning process for the stirring member. Returning to the flowchart showing the processing example of the density adjustment method of FIG.

<Example of processing procedure of density adjustment method>
In FIG. 6, the stirring member cleaning process in step S <b> 11 ends as described above, proceeds to step S <b> 12, and starts the density adjustment process.

  In step S <b> 12, the developer whose density is to be adjusted, for example, the collected developer in the collected developer tank 53 is accommodated in the density adjusting tank 51 as a density adjusting developer. That is, step S12 functions as a developer accommodation step. Of course, as described above, the cleaning developer may be left as it is. At that time, it is input as it is.

  Subsequently, also in step S13, the driving device 63 drives the stirring member 62 according to an instruction from the control unit 61, and starts stirring the density adjusting developer at a predetermined rotational speed. In addition, the load detection device 64 measures the current value as the stirring load. That is, step S13 functions as a load detection process.

  The next step S14 and subsequent steps are control steps.

  The next step S14 compares the measured current value measured by stirring the density adjusting developer with a target range based on a predetermined target value.

  If the measured current value is within the target range (step S14: Yes), the process proceeds to step S18. That is, the density adjustment is finished. If the measured current value is not within the target range (step S14: No), the process proceeds to step S15.

  Step S15 determines whether or not the measured current value outside the target range is below the target range. If it is below the target range (step S15: Yes), step S16 is executed. If it exceeds the target range (step S15: No), step S17 is executed.

  Step S16 is a first replenishment step. Since the measured density adjusting developer is below the target density, the first replenishment developer (high density developer) is replenished. Thereafter, the process returns to step S13, and the processing from the load detection step is repeated.

  Step S17 is a second replenishment step. Since the measured density adjusting developer exceeds the target density, the second replenishment developer (low density developer) is replenished. Thereafter, the process returns to step S13, and the processing from the load detection step is repeated.

  As described above, step S16 and step S17 function as a replenishment process.

  After exiting the iterative process in step S14 and completing the adjustment in step S18, step S19 is further executed to discharge the adjusted developer in the density adjustment tank 51 and supply it to the developer tank 44 for use in development. To do.

  At this time, the concentration adjustment tank 51 becomes empty under the control of the control unit 61. Until the next density adjustment is performed after becoming empty, for example, a time count for determining the next cleaning execution is performed.

  This is the end of the description of the processing procedure example of the density adjustment method of the developer density adjustment apparatus.

  When the concentration was adjusted using the concentration adjusting device in FIG. 3 and the concentration measuring unit in FIG. 4, an experiment was conducted to confirm the effect of cleaning the stirring member. The result of evaluating the effect of concentration on the accuracy of concentration measurement will be described.

<Device conditions>
The apparatus conditions are shown below.

  The concentration adjusting tank has an inner diameter of φ85 mm. The stirring blade was provided with 6 blades having a diameter of 75 mm and a height of 10 mm at a position 10 mm from the bottom.

  As an opening, an opening having a height of 20 mm and a width of 30 mm was provided at a position 80 mm from the bottom.

  The rotation speed of the stirring blade was 200 rpm when adjusting the concentration.

<Developer>
As the liquid developer, a liquid developer in which toner was dispersed in a carrier liquid was used.

  An IP solvent liquid was used as a carrier liquid, and a toner was prepared by wet pulverizing polyester toner having an average particle diameter of 1.9 μm.

  The predetermined density for density adjustment was set at 25% T / C ratio.

<Experiment method>
The procedure as an experimental method is shown below.

  (1) After density adjustment processing to a predetermined density (T / C ratio 25%) using the density adjusting device and developer, the density adjusting tank was emptied and left for one week.

  (2) Then, about the Example, the following factors were changed and the stirring blade was cleaned. The comparative example was not cleaned as it was.

  For the cleaning developer, the following five types of cleaning developers were used.

a. Carrier liquid 100% (mass ratio)
b. Carrier liquid 70% Recovered developer 30% (mass ratio)
c. Carrier liquid 50% Recovered developer 50% (mass ratio)
d. Carrier liquid 70% Recovered developer 30% (mass ratio)
e. Collected developer 100% (mass ratio)
The experiment was conducted with the carrier liquid having a concentration of 0% and the recovered developer having a concentration of 20% and a concentration of 28%. Each cleaning developer was charged immediately before cleaning and discharged immediately after cleaning. The input amount of the cleaning developer was set such that the stirring blade did not squeeze out from the liquid surface. It is about 1/4 of the density adjustment.

  Regarding the stirring blade rotation speed, the stirring blade was rotated in three modes.

a. Normal rotation (same as the density adjustment r = 200 rpm)
b. High-speed rotation (2r = 400rpm double the density adjustment)
c. Variable speed rotation (r = 200rpm, 1.5r, 2r)
The stirring blade rotation time was constant for 5 minutes.

  FIG. 5 shows the relationship between time and rotational speed in each mode. 5A shows normal rotation, FIG. 5B shows high speed rotation, and FIG. 5C shows speed variable rotation.

  In addition, in some examples, an ultrasonic vibration member was provided, and ultrasonic vibration was applied during cleaning.

  (3) A developer having a known density (T / C ratio 25%) was placed in the density adjustment tank, and the stirring load of the stirring blade was measured to determine the toner density. In order to evaluate the effect of cleaning, the concentration measurement results in each example and comparative example were evaluated by the following evaluation methods.

<Evaluation method>
The rank deviation of the measurement result deviation (±%) from the known concentration (25%) as the target value was evaluated as follows.

Rank 5 Deviation from the target value is less than 0.6% Rank 4 Deviation from the target value is 0.6% or more and less than 0.8% Rank 3 Deviation from the target value is 0.8% or more and 1.0% Less than Rank 2 Deviation from target value is 1.0% or more and less than 3.0% Rank 1 Deviation from target value is 3.0% or more Rank 5 has good measurement accuracy and rank 1 is bad. Rank 3 or higher is an OK level.

<Evaluation results>
Table 1 shows cleaning conditions and evaluation results of Examples 1 to 19 and Comparative Examples 1 and 2.

  As shown in the results of Table 1, the following can be understood.

  1. All of the evaluation results of Examples 1 to 19 in which cleaning was performed by stirring operation under a stirring condition different from that at the time of concentration adjustment were the same as in Comparative Example 1 in which cleaning operation was performed under the same condition as that for concentration adjustment. A better rank than the evaluation result of Comparative Example 2 that was not performed is shown. By performing cleaning before entering the density adjustment process, the toner or the like adhering to the stirring blade is removed, and the rotational load measurement, that is, the density measurement accuracy is stable. Thereby, density adjustment processing with stable accuracy can be performed.

  Each cleaning developer that had been used was separately reused for density adjustment, but there was no obstacle to density adjustment and subsequent use in the developing device.

  2. Each of Examples 1 to 19 has a rank of 3 or higher. However, the lower the concentration of the cleaning developer, the higher the cleaning efficiency and the higher the rank evaluation. In order to further improve the cleaning effect, it is desirable to clean using a cleaning developer having as low a concentration as possible.

  As can be seen from the results, the cleaning developer is preferably a liquid developer having a concentration lower than the carrier liquid or a predetermined concentration and lower than the concentration of the liquid developer for adjusting the concentration. As such a developer, a second replenishment developer having a concentration lower than a predetermined concentration or a mixed developer of a second replenishment developer and a liquid developer for adjusting the concentration may be used.

  3. Each of Examples 1 to 19 has a rank of 3 or higher, but the higher the stirring blade rotation speed during cleaning, the easier it is to remove the centrifugal force and the higher the rank evaluation tends to be seen. In order to further improve the cleaning effect, it is desirable to perform cleaning using a stirring blade rotating as fast as possible.

  In addition, it is desirable to change the rotation speed during cleaning because the pressure on the stirring blade is applied to facilitate the removal.

  4). In Examples 10 and 11, ultrasonic vibration is applied during cleaning. By applying an ultrasonic wave, it becomes easy to remove by vibration, and a tendency of good rank evaluation is seen. In order to further improve the cleaning effect, it is desirable to clean by adding ultrasonic vibration if possible.

  As described above, according to the developer concentration adjusting device, the developer concentration adjusting method, and the image forming apparatus using them according to the present embodiment, the developer for cleaning the stirring member into the concentration adjusting tank at the start of the concentration adjustment. In the concentration adjusting tank, the stirring member is immersed in a cleaning developer to perform a stirring operation, and the stirring member is cleaned.

  As a result, it is possible to prevent the occurrence of abnormal toner density detection due to dry fixing of the residual developer to the stirring member, and to enable accurate density adjustment.

  In addition, the above-mentioned embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 2 Charging device 3 Exposure device 4 Liquid developing device 5 Transfer device 6 Cleaning device 7 Transfer material 8 Liquid developer 10 Image forming device 41 Developing roller (developer carrier)
42 Conveying roller 43 Supply roller 44 Developer tank 45 Restricting member 46 Removal member 50 Developer concentration measuring section 51 Concentration adjusting tank 51a Opening 52 Discharged developer tank 53 Recovered developer tank 54 First supply developer tank (high density) Developer tank)
55 Second supply developer tank (low density developer tank)
54a First supply means 55a Second supply means 60 Developer concentration adjusting device 61 Control unit (control means)
62 Stirring member (stirring blade)
63 Drive unit (motor)
64 Load detection device (load detection means)
81 Liquid level during stirring of developer for density adjustment

Claims (18)

In order to adjust the toner concentration of the liquid developer containing the toner and the carrier liquid to a predetermined concentration,
A density adjusting tank for storing a liquid developer for density adjustment;
An agitation member for agitating the liquid developer contained in the concentration adjustment tank;
Load detecting means for detecting a stirring load when the liquid developer is stirred by the stirring member;
Replenishment means for replenishing the density adjustment tank with a replenishment developer for density adjustment;
Control means for controlling replenishment of the replenishment developer by the replenishment means based on the stirring load detected by the load detection means, and adjusting the concentration of the liquid developer,
The control means includes
In order to remove the toner remaining on the stirring member in the density adjusting tank before the liquid developer is contained in the empty density adjusting tank and density adjustment is performed, the stirring member is removed. A developer concentration adjusting apparatus, wherein the developer concentration is controlled to be cleaned by being stirred under a stirring condition different from that when performing the density adjustment while being immersed in a liquid developer for cleaning. The cleaning liquid developer used at the time of cleaning the stirring member by the control means,
The developer concentration adjusting apparatus according to claim 1, wherein the developer concentration adjusting device is a liquid developer having a concentration lower than that of the carrier liquid or the predetermined concentration and lower than a concentration of the concentration adjusting liquid developer. The replenishing means is
A first supply means for supplying a first supply developer having a concentration higher than the predetermined concentration to the concentration adjustment tank, and a second supply developer having a concentration lower than the predetermined concentration is supplied to the density adjustment tank. A second supply means for
The developer concentration according to claim 2, wherein the cleaning liquid developer is a second replenishment developer or a mixed developer of a second replenishment developer and a liquid developer for concentration adjustment. Adjustment device. When cleaning the stirring member by the control means,
4. The developer concentration adjusting apparatus according to claim 1, wherein the agitation member is driven at a higher speed than when the agitation member is agitated to detect the agitation load. 5. When cleaning the stirring member by the control means,
The developer concentration adjusting apparatus according to any one of claims 1 to 4, wherein the stirring member is driven at a different speed. An ultrasonic vibration member in the concentration adjustment tank;
When cleaning the stirring member by the control means,
The developer concentration adjusting apparatus according to claim 1, wherein vibration by the ultrasonic vibration member is added. The control means includes
The time after the liquid developer is discharged from the concentration adjustment tank and becomes empty is measured, and it is determined whether or not the stirring member is to be cleaned based on the measured time. Item 7. The developer concentration adjusting apparatus according to any one of Items 1 to 6. The concentration adjustment tank is a cylindrical container,
An opening that overflows when the contained liquid developer reaches a certain liquid level,
The load detecting means includes
The liquid developer in the concentration adjusting tank is agitated by the agitating member and overflows from the opening, or after the agitation load is detected. The developer concentration adjusting apparatus according to any one of the above. In order to adjust the toner concentration of the liquid developer containing the toner and the carrier liquid to a predetermined concentration,
A developer storage step of storing a liquid developer for concentration adjustment in the concentration adjustment tank;
A load detection step of detecting a stirring load while stirring the liquid developer contained in the concentration adjustment tank by a stirring member;
A replenishment step of replenishing the density adjusting tank with a replenishment developer for density adjustment;
A control step of controlling execution of the replenishment step based on the stirring load detected in the load detection step and adjusting the concentration of the liquid developer,
In the control step,
In order to remove the toner remaining on the stirring member in the density adjusting tank before the liquid developer is contained in the empty density adjusting tank and density adjustment is performed, the stirring member is removed. A developer concentration adjusting method, wherein the developer is controlled to be cleaned by being stirred under a stirring condition different from that when performing the concentration adjustment while immersed in a cleaning liquid developer. The cleaning liquid developer used at the time of cleaning the stirring member in the control step,
The developer concentration adjusting method according to claim 9, wherein the developer concentration is lower than the concentration of the carrier liquid or the predetermined concentration and lower than the concentration of the liquid developer for adjusting the concentration. The replenishment step includes
A first replenishment step of replenishing the density adjustment tank with a first replenishment developer having a higher density than the predetermined density; and a second replenishment developer having a density lower than the predetermined density is replenished to the density adjustment tank. And a second replenishment step
The developer concentration according to claim 10, wherein the cleaning liquid developer is a second replenishment developer or a mixed developer of a second replenishment developer and a liquid developer for concentration adjustment. Adjustment method. When cleaning the stirring member in the control step,
12. The developer concentration adjusting method according to claim 9, wherein the stirring member is driven at a higher speed than when stirring to detect the stirring load. When cleaning the stirring member in the control step,
The developer concentration adjusting method according to any one of claims 9 to 12, wherein the stirring member is driven while changing a speed. When cleaning the stirring member in the control step,
The developer concentration adjusting method according to any one of claims 9 to 13, wherein vibration by an ultrasonic vibration member is added. When cleaning the stirring member in the control step,
The time after the liquid developer is discharged from the concentration adjustment tank and becomes empty is measured, and it is determined whether or not the stirring member is to be cleaned based on the measured time. Item 15. The developer concentration adjusting method according to any one of Items 9 to 14. In the developer containing step,
When the liquid developer accommodated in the concentration adjustment tank having a cylindrical shape is in a cylindrical shape and reaches a certain liquid level, it overflows from the opening,
In the load detection step,
The liquid developer in the concentration adjusting tank is stirred by the stirring member and overflows from the opening or after the stirring load is detected. The developer concentration adjusting method according to any one of the above items. An image carrier that forms a latent image on the surface;
A liquid developing device that develops a latent image on the surface of the image carrier with a liquid developer and forms a toner image;
The developer concentration adjusting device according to any one of claims 1 to 8,
An image forming apparatus, wherein the liquid developer adjusted to a predetermined developer concentration by the developer concentration adjusting device is supplied to the liquid developing device. The image forming apparatus according to claim 17, wherein when the power of the image forming apparatus is turned on or when driving is started, the control unit of the developer concentration adjusting device controls to clean the stirring member.

Images