JP2011095379A - Image forming apparatus and cartridge for developer replenishment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of performing calibration correctly without requiring labor and time for producing reference developer for calibration even if a cartridge for developer replenishment is changed, that is, the kind or lot of liquid developer is changed when adjusting toner density of the liquid developer by using alternative characteristic, and to provide a cartridge for developer replenishment. <P>SOLUTION: The reference developer and developer for replenishment are stored in the single cartridge for developer replenishment. The calibration for density adjustment is performed by using the reference developer having prescribed toner density, and the density adjustment is performed by using the developer for replenishment having higher density than the reference developer on the basis of a set target value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus provided with a liquid developing device for developing a latent image formed on the surface of an image carrier using a liquid developer containing toner and a carrier liquid to form a toner image, and image formation therefor The present invention relates to a developer replenishing cartridge that is mounted on an apparatus and replenishes the liquid developer.

  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.

  In Patent Document 2, a correction table including temperature correction and the like is held, and temperature correction is performed every time density adjustment is performed. In addition, a technique has been proposed in which the correction table is recalibrated when the developer lot is changed, and the viscosity is varied by the lot to ensure measurement accuracy.

JP 2008-209716 A JP 2009-69586 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.

  In Patent Documents 1 and 2, the rotational torque (motor current value) of the stirring member is measured as the stirring load, and the concentration is adjusted to a predetermined value (target current value). The adjustment is performed using a first supply developer having a density higher than a desired density and a second supply developer having a low density.

  However, if the type or lot of the liquid developer changes, the viscosity of the liquid developer for obtaining a predetermined concentration may change, and the target value may also change. This is because the liquid developer involves a number of parameters such as chargeability, particle size, and viscosity, and it is difficult to manufacture the liquid developer so that their physical properties are all equal.

  Therefore, when the type or lot of the liquid developer changes, the target value for density adjustment, which is a substitute characteristic, must also be changed. That is, it is necessary to perform calibration again using a new liquid developer and reset the target value.

  Normally, a new liquid developer is supplied using a developer replenishing cartridge. Therefore, calibration is required every time a new cartridge is mounted. However, the density adjustment described in Patent Document 1 does not describe the calibration itself every time the cartridge is mounted.

  In addition, in the density adjustment described in Patent Document 2, although there is a description about calibration, a high-concentration first supply developer and a low-concentration second supply developer are mixed to produce a reference development having a predetermined density. Agents must be made each time. This takes time and at the same time, if there is variation in the amount of replenishment developer supplied, the reference developer concentration itself may fluctuate and correct calibration may not be possible.

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

  An object of the present invention is to provide a developer replenishment cartridge, that is, a liquid in an image forming apparatus that replenishes a liquid developer with a developer replenishment cartridge when adjusting the toner concentration of the liquid developer using substitute characteristics. By providing an image forming apparatus and a developer replenishing cartridge that can be calibrated correctly without the need to create a reference developer for calibration even if the type or lot of the developer is changed. is there.

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

1. A liquid developing device that develops a latent image formed on the surface of the image carrier using a liquid developer containing toner and a carrier liquid to form a toner image, is equipped with a developer replenishing cartridge, and the liquid developing An image forming apparatus for replenishing an agent,
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;
A developer concentration adjusting device having control means for controlling the 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. In the image forming apparatus,
The developer concentration adjusting device is
Using a reference developer having a predetermined toner density stored in the mounted developer replenishing cartridge, calibration for density adjustment is performed,
The density adjustment is performed using a replenishment developer having a higher concentration than the reference developer contained in the same cartridge as the replenishment developer for the density adjustment based on the target value set by the calibration. Forming equipment.

2. The replenishing means in the developer concentration adjusting device is:
First replenishing means for replenishing the density adjusting tank with the replenishing developer contained in the developer replenishing cartridge as a first replenishing developer;
2. The image forming apparatus according to claim 1, further comprising: a second replenishing unit that replenishes the density adjustment tank with a second replenishment developer having a lower concentration than the reference developer.

3. In the developer concentration adjusting device,
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. 3 or 3. Image forming apparatus.

4). The developer replenishing cartridge that is mounted on the image forming apparatus according to any one of 1 to 3 and replenishes a liquid developer,
The reference developer and the replenishment developer are individually accommodated in a single cartridge,
The reference developer and the replenishment developer are liquid developers containing toner of the same production lot and the same carrier liquid, and the mass ratio of the carrier liquid in each developer is different. Refill cartridge.

  According to the image forming apparatus and the developer replenishing cartridge of the present invention, the reference developer and the replenishing developer are accommodated in a single developer replenishing cartridge, and the reference developer having a predetermined toner concentration is used. Then, calibration for density adjustment is performed, and density adjustment is performed using a replenishment developer having a higher density than the reference developer based on the set target value.

  As a result, when adjusting the toner concentration of the liquid developer using the substitute characteristics, even if the type or lot of the developer replenishment cartridge, that is, the liquid developer is changed, it takes time and effort to create a reference developer for calibration. It is unnecessary and can be calibrated correctly.

1 is a cross-sectional view illustrating a schematic configuration example of an image forming apparatus 10 according to the present embodiment. 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. FIG. 3 is a configuration diagram illustrating a schematic configuration example of a developer replenishment cartridge 70 according to the present embodiment. 5 is a flowchart illustrating an example of a calibration processing procedure of a developer concentration measuring unit 50 using a reference developer 71. 5 is a flowchart illustrating an example of a processing procedure of density adjustment by the developer density adjusting device 60.

  An embodiment of an image forming apparatus 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, non-volatile solvent at room temperature 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 in order to adjust it to a desired concentration and reuse it.

  The recovered developer adjusted to a desired 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 desired 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 contains, for example, a liquid developer having a concentration lower than a desired 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 supply developer or the second supply developer is supplied in accordance with a comparison result with a desired density (a desired current value, that is, a target current value). That is, when the concentration is lower than the desired 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 desired concentration.

  When the density adjusting developer reaches a desired density, the density adjustment is completed, 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 adjusting 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 driving 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 desired 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 concentration adjustment is stirred using the stirring unit. 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 measurement method 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. The present invention 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, by the rotation of the stirring blade 62, the developer liquid moves outward due to centrifugal force, 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, a predetermined liquid level, that is, a 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 blades 62 and the like is measured. The stirring blade 62 may be rotated at a predetermined rotational speed, and the current value at that time may be measured with an ammeter 64.

  A motor current value as a load of stirring with respect to a developer (reference developer) having a desired 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.

(Calibration when changing cartridge for replenishing developer)
As described above, as a method for measuring the developer concentration, that is, the viscosity, a characteristic value that can be measured relatively easily, such as the rotational torque when the developer is stirred, can be used as a substitute characteristic of the viscosity.

  However, as already described, when the type or lot of the liquid developer changes, the viscosity of the liquid developer for obtaining a predetermined concentration may change, and the target value of the substitute characteristic may also change. This is because a number of parameters such as chargeability, particle size, and viscosity are involved in the liquid developer, and thus it is difficult to manufacture the liquid developer so that all of the physical properties are equal.

  Therefore, when the type or lot of the liquid developer changes, the target value for density adjustment, which is a substitute characteristic, must also be changed. That is, it is necessary to perform calibration again using a new liquid developer and reset the target value.

  The image forming apparatus according to the present invention has a configuration in which a developer replenishing cartridge is mounted and a new liquid developer is supplied. Therefore, it is controlled so that calibration is performed every time a new cartridge is mounted.

  However, the developer replenishment cartridge contains the replenishment developer and is not necessarily filled with the developer having a desired toner concentration. In order to increase the actual usage amount as a liquid developer as much as possible compared to the volume of the cartridge for replenishing the developer, the supplementary charge developer is stored in a so-called conc liquid state having a higher concentration than the desired toner concentration. Yes.

  In actual use, if the developer density adjusting device 60 is used to reduce the density and the toner density is adjusted to a desired toner density, the actual usage amount can be increased.

  However, although there is no problem with the density adjustment work itself, as described above, calibration is performed using a new liquid developer every time a new cartridge for replenishing the developer is installed, that is, every time the type or lot of the liquid developer is changed. There is a problem to start over.

  The replenishment developer, that is, the new liquid developer itself does not have the desired toner concentration, so the high concentration replenishment developer and the low concentration replenishment developer (preferably carrier liquid) are mixed and used for calibration. This is because a developer (reference developer) having a concentration of 1 must be prepared each time.

  This takes time and at the same time, if there is variation in the amount of replenishment developer supplied, the concentration of the prepared reference developer itself may fluctuate and correct calibration may not be possible.

  In the present embodiment, the developer replenishment cartridge is configured as follows, so that the calibration with the developer concentration adjusting device can be performed easily and accurately, and the above problem is solved.

<Configuration of developer replenishment cartridge>
FIG. 5 shows a schematic configuration example of a developer replenishing cartridge that is used by being mounted on the image forming apparatus according to the present embodiment. A schematic configuration example of the developer replenishing cartridge will be described with reference to FIG.

  In FIG. 5, reference numeral 70 denotes a developer replenishment cartridge.

  The developer replenishment cartridge 70 contains two types of liquid developers, that is, a reference developer 71 and a replenishment developer 72, independently in a single cartridge.

  The developer replenishment cartridge 70 is mounted and used in the image forming apparatus. The two types of liquid developers in the cartridge are supplied to the developer concentration adjusting device 60 through respective paths. That is, the reference developer 71 is sent to the density adjustment tank 51 for calibration, and the replenishment developer 72 is sent to the first replenishment developer tank 54 as a replenishment developer.

  The reference developer 71 is a developer having a desired toner concentration and is accommodated for calibration for density adjustment. When the calibration is completed and a new target is set for the developer contained in the cartridge, the liquid developer can be used for development as a liquid developer adjusted to a normal desired density.

  The replenishment developer 72 is a developer having a higher density than the reference developer, and is accommodated as a replenishment developer for adjusting the density. It is used to adjust the density by replenishing the developer for density adjustment. Of course, the developer for replenishment itself is used as a developer for density adjustment. It can also be used for development as a developer.

  The reference developer 71 and the replenishment developer 72 are liquid developers composed of toner of the same production lot and the same carrier liquid, and the mass ratio of the carrier liquid is different. Therefore, the target calibrated and set using the reference developer 71 can be applied as it is to the replenishment developer 72 of the same cartridge, and the developer replenishment cartridge 70 is replaced without the need for creating a reference developer. And every time it is installed, it can be easily calibrated correctly.

<Proofing procedure>
FIG. 6 is a flowchart showing an example of a schematic procedure of the calibration process using the reference developer. An example of a schematic processing procedure of calibration using the reference developer will be described with reference to FIG.

  Each time the developer replenishing cartridge 70 is replaced and mounted, the following calibration process is started first.

  First, in step S1, as a preparation, it is confirmed whether or not the liquid developer remains in the density adjustment tank 51. When there is a residual developer, the control unit 61 discharges the residual developer to the developer tank 44 or the like according to a predetermined processing procedure, and makes the density adjustment tank 51 empty.

  In step S <b> 2, a developer having a desired density for calibration for density adjustment, that is, a reference developer 71 is accommodated in the density adjustment tank 51 from the attached developer replenishing cartridge 70.

  Subsequently, in step S3, the driving device 63 drives the stirring member 62 according to an instruction from the control unit 61, and starts stirring the reference developer 71 at a predetermined rotational speed. In addition, the load detection device 64 measures the current value as the stirring load in a state after overflowing from the opening 51a or after the opening.

  The next step S4 performs calibration processing. That is, a target value or a target range is set based on a measured current value measured by stirring the reference developer 71, and the control unit 61 stores it.

  Calibration is completed in step S4. After that, step S5 is executed, and the calibrated reference developer 71 in the density adjustment tank 51 is discharged and supplied to the developer tank 44 for use in development.

  Step S6 prepares for the next density adjustment. For example, in order to use the replenishment developer 72 in the attached developer replenishment cartridge 70 as a high-concentration replenishment developer, the developer replenishment cartridge 70 is accommodated in the first replenishment developer tank 54.

  Alternatively, since the replenishment developer 72 itself is subjected to density adjustment and used for development, it may be accommodated in the density adjustment tank 51 as a density adjustment developer.

  Thus, the calibration processing procedure is completed, and the process enters the next density adjustment process using a new developer based on the newly set target.

(Density adjustment processing procedure example)
FIG. 7 is a flowchart showing an example of a processing procedure of density adjustment of the developer density adjusting device. With reference to FIG. 7, an example of the density adjustment processing procedure of the developer density adjusting device will be described.

  When developer density adjustment is started, first, in step S11, a liquid developer for density adjustment for density adjustment is set. The control unit 61 sets the collected developer in the collected developer tank 53 as a liquid developer for density adjustment according to a predetermined processing procedure. Alternatively, the replenishment developer 72 in the developer replenishment cartridge 70 is set as a liquid developer for density adjustment.

  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.

  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 in a state after overflowing from the opening 51a or after the opening.

  In the next step S14, the control unit 61 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.

  In step S16, since the measured density adjusting developer is below the target density, the first replenishing means is the first replenishing developer (high concentration developer, here, the replenishing developer 72). Perform replenishment. Thereafter, the process returns to step S13, and the processing from there is repeated.

  In step S17, since the measured density adjusting developer exceeds the target density, the second replenishing means replenishes the second replenishing developer (preferably a low-concentration developer, preferably the carrier liquid itself). . Thereafter, the process returns to step S13, and the processing from there is repeated.

  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.

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

  As described above, according to the image forming apparatus and the developer replenishing cartridge according to the present embodiment, the reference developer and the replenishing developer are accommodated in a single developer replenishing cartridge, and a predetermined toner is contained. Calibration for density adjustment is performed using a density reference developer, and density adjustment is performed using a replenishment developer having a higher density than the reference developer based on the set target value.

  As a result, when adjusting the toner concentration of the liquid developer using the substitute characteristics, even if the type or lot of the developer replenishment cartridge, that is, the liquid developer is changed, it takes time and effort to create a reference developer for calibration. It is unnecessary and can be calibrated correctly.

  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)
70 Developer Replenishment Cartridge 71 Reference Developer 72 Replenishment Developer 81 Liquid Level at Stirring of Concentration Developer

Claims (4)

A liquid developing device that develops a latent image formed on the surface of the image carrier using a liquid developer containing toner and a carrier liquid to form a toner image, is equipped with a developer replenishing cartridge, and the liquid developing An image forming apparatus for replenishing an agent,
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;
A developer concentration adjusting device having control means for controlling the 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. In the image forming apparatus,
The developer concentration adjusting device is
Using a reference developer having a predetermined toner density stored in the mounted developer replenishing cartridge, calibration for density adjustment is performed,
The density adjustment is performed using a replenishment developer having a higher concentration than the reference developer contained in the same cartridge as the replenishment developer for the density adjustment based on the target value set by the calibration. Forming equipment. The replenishing means in the developer concentration adjusting device is:
First replenishing means for replenishing the density adjusting tank with the replenishing developer contained in the developer replenishing cartridge as a first replenishing developer;
The image forming apparatus according to claim 1, further comprising: a second replenishing unit that replenishes the density adjustment tank with a second replenishment developer having a lower concentration than the reference developer. In the developer concentration adjusting device,
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. 3. The image forming apparatus described. A developer replenishing cartridge mounted on the image forming apparatus according to claim 1 for replenishing a liquid developer,
The reference developer and the replenishment developer are individually accommodated in a single cartridge,
The reference developer and the replenishment developer are liquid developers containing toner of the same production lot and the same carrier liquid, and the mass ratio of the carrier liquid in each developer is different. Refill cartridge.

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