JP4831031B2 - Developer density adjusting device, developer density adjusting method, and image forming apparatus - Google Patents

Description

  In the present invention, the toner concentration of the liquid developer in which the toner is dispersed in the carrier liquid is represented by the viscosity of the liquid developer, and the change of the viscosity is used as an index to adjust the toner concentration of the liquid developer. The present invention relates to a developer concentration adjusting device, a developer concentration adjusting method, and an image forming apparatus.

  2. Description of the Related Art An electrophotographic image forming apparatus that forms an electrostatic latent image on a photoconductor (photosensitive drum), 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, but after developing the latent image on the image carrier, the density often changes considerably, such as by consuming a considerable amount of toner. . 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, replenish the developer for density adjustment (such as high density developer or low density developer) to adjust the density of the collected developer. Techniques have been proposed to do this.

  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 the developer, a characteristic value that can be measured relatively easily, such as the rotational torque during stirring of the developer, can be used as a substitute characteristic of the viscosity.

  However, these methods also have a problem that when the temperature of the liquid developer (hereinafter, also simply referred to as the liquid temperature) varies, the viscosity, that is, the rotational torque characteristics, etc. vary.

  For this reason, the relationship between the temperature and the viscosity characteristic of the liquid developer is examined in advance, and the viscosity is corrected based on the measured temperature of the liquid developer with reference to the table (or conversion formula). It has been broken.

  However, when the type or lot of the developer changes, the correction method also needs to be changed. Since the relationship between the liquid temperature and the viscosity characteristic is unique to the liquid developer, it is not possible to deal with all the developers with one correction formula.

  For this reason, a technique has been proposed in which a table is held for each type of developer, and a correction table is selectively used according to the developer (see, for example, Patent Document 1).

  In Patent Document 1, when correcting the instrumental difference of a flow meter that measures the flow rate of a liquid, the type of liquid whose flow rate is to be measured is determined, and the temperature of the liquid is corrected using a correction table prepared for each type. A technique has been proposed in which the output value is output and the instrumental error is corrected based on the output value.

  If these techniques are applied to the viscosity measurement of liquid developer, each temperature correction table is prepared in advance and used for developers using different toners. Viscosity characteristics that are appropriately temperature-corrected according to the agent can be obtained.

  However, a recognition mechanism for discriminating complicated developer types is required. In addition, even with the same developer, it is difficult to discriminate against slightly different toners or variations in toner production, and it is troublesome to prepare and hold a large number of correction tables.

  A technique has also been proposed in which necessary quality information is described in a container or the like in advance and processing is changed based on the information instead of determining the developer (for example, see Patent Document 2).

  Japanese Patent Application Laid-Open No. 2004-228620 proposes a technique for describing ink quality information in an ink cartridge and changing image forming conditions in accordance with the quality information.

  If such a technique is applied to a liquid developer, it is possible to select and use a temperature correction table corresponding to the difference between toners and toner fluctuations by acquiring respective information. .

However, it is still necessary to prepare and hold a large number of correction tables. Further, it is necessary to obtain not only a large number of correction tables but also quality information corresponding to the correction tables by measuring them in advance and writing them in the container. A device for reading it is also necessary.
JP 7-174607 A JP 2004-322496 A

  As described above, in order to adjust the density of the liquid developer, a technique for measuring the viscosity characteristic as a substitute characteristic of density has been proposed, but the influence of the liquid temperature during measurement is large, and it is necessary to perform temperature correction. It is. However, it is necessary to prepare a large number of temperature correction tables according to the difference in liquid developer, and a mechanism for discriminating the difference in liquid developer is required to select which table is applied. Become.

  The object of the present invention is to solve the above-mentioned problems and to measure the viscosity characteristics as a substitute characteristic for adjusting the concentration of the liquid developer. In some cases, there is no need for a mechanism for recognizing the difference in developer or for transferring information about the developer, and there is no need to hold a large number of tables. It is another object of the present invention to provide a developer concentration adjusting apparatus and a developer concentration adjusting method that can easily and accurately adjust the concentration of a liquid developer by calculating the viscosity characteristics with appropriate temperature correction. Another object of the present invention is to provide an image forming apparatus in which the concentration of the collected developer can be easily and accurately adjusted using them and can be reused efficiently.

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

  1. A developer concentration adjusting device for adjusting a toner concentration of a liquid developer in which toner is dispersed in a carrier liquid, using a change in viscosity of the liquid developer as an index, and a viscosity characteristic value indicating the viscosity of the liquid developer Correction table storage means for storing a viscosity correction means for measuring the liquid temperature, a liquid temperature measurement means for measuring the liquid temperature of the liquid developer, and a reference correction table indicating a relationship between a predetermined reference viscosity characteristic value and the liquid temperature Then, using the liquid developer for calibration, the reference correction table is corrected based on the viscosity characteristic value and the liquid temperature measured by the viscosity measuring unit and the liquid temperature measuring unit, and the target viscosity characteristic value and the liquid Correction table calibrating means for creating a specific correction table showing the relationship with temperature, viscosity characteristic values and liquid temperature were measured for the liquid developer to be subjected to density adjustment, and measured based on the specific correction table. Developer concentration adjusting device whose serial viscosity characteristic value, characterized in that it comprises a concentration adjusting unit for performing the toner density adjustment of the liquid developer so as to be equal to the target viscosity characteristic value.

  2. The correction table calibration means uses the ratio between the measured viscosity characteristic value and the reference viscosity characteristic value at the liquid temperature at which the liquid developer having the target toner concentration is newly measured as an intrinsic constant, and the reference correction table. 2. The developer concentration adjusting apparatus according to 1, wherein the intrinsic correction table is created by uniformly applying the intrinsic constant to each reference viscosity characteristic value for each liquid temperature.

  3. Replenishment means for replenishing any one of a plurality of density adjustment replenishment developers with different toner concentrations to the liquid developer for density adjustment, the density adjustment means, the measured viscosity characteristic value, The replenishment of the replenishment developer by the replenishing means is controlled so that the target viscosity characteristic value corrected for the liquid temperature is equal, and the toner concentration of the liquid developer is adjusted to the target toner concentration. The developer concentration adjusting apparatus according to 1 or 2, wherein

  4). 4. The viscosity characteristic value indicating the viscosity of the liquid developer measured by the viscosity measuring unit is a motor current value as a load for stirring the liquid developer. The developer concentration adjusting device according to 1.

  5. A developer concentration adjusting method for adjusting a toner concentration of a liquid developer in which toner is dispersed in a carrier liquid, using a change in viscosity of the liquid developer as an index, and a viscosity characteristic value indicating the viscosity of the liquid developer Viscosity characteristics measured in the viscosity measuring step and the liquid temperature measuring step using a liquid temperature measuring step for measuring the liquid developer, a liquid temperature measuring step for measuring the liquid temperature of the liquid developer, and a liquid developer for calibration Based on the value and liquid temperature, the standard correction table that shows the relationship between the predetermined reference viscosity characteristic value and the liquid temperature is corrected, and a unique correction table that shows the relationship between the target viscosity characteristic value and the liquid temperature is created The viscosity characteristic value and the liquid temperature are measured for the liquid developer that is the object of the table calibration step and density adjustment, and based on the inherent correction table, the measured viscosity characteristic value is equal to the target viscosity characteristic value. To the liquid Developer concentration adjusting method characterized by and a concentration adjustment step for toner density adjustment image agent.

  6). In the correction table calibration step, a ratio of the measured viscosity characteristic value to the reference viscosity characteristic value at the liquid temperature at which the liquid developer having the target toner concentration is newly measured is set as an intrinsic constant, and the reference correction table is used. 6. The developer concentration adjusting method according to 5, wherein the inherent correction table is created by uniformly applying the inherent constant to each reference viscosity characteristic value for each liquid temperature.

  7). A replenishment step of replenishing any one of a plurality of density adjustment replenishment developers with different toner concentrations to the liquid developer for density adjustment, the density adjustment step comprising: a measured viscosity characteristic value; The replenishment of the replenishment developer in the replenishment step is controlled so that the target viscosity characteristic value corrected for the liquid temperature is equal, and the toner concentration of the liquid developer is adjusted to become the target toner concentration. 5. The developer concentration adjusting method according to 5 or 6.

  8). The viscosity characteristic value indicating the viscosity of the liquid developer in the viscosity measurement step is a motor current value as a load for stirring the liquid developer, according to any one of 5 to 7, Developer density adjustment method.

  9. An image forming apparatus comprising: an image carrier that forms a latent image on a surface; and a liquid developing device that develops a latent image on the surface of the image carrier with a liquid developer to form a toner image. 5. A developer concentration adjusting device according to any one of claims 4 to 4, wherein a liquid developer adjusted to a desired developer concentration by the developer concentration adjusting device is supplied to the liquid developing device. Image forming apparatus.

  According to the developer concentration adjusting device and the developer concentration adjusting method according to the present invention, in order to adjust the concentration of the liquid developer, the viscosity property is used as the substitute property of the concentration, and the adjustment is made so as to achieve the target viscosity property. It can be done as follows.

  In other words, in order to correct the target viscosity characteristic by the liquid temperature, a reference correction table that is determined and held in advance is calibrated to create a unique correction table. Based on this inherent correction table, the target viscosity characteristic corrected with the measured liquid temperature is compared with the measured viscosity characteristic, and an adjustment is made to make the measured viscosity characteristic larger or smaller.

  As a result, even when the toner of the liquid developer is slightly different or there is a lot fluctuation of the toner, there is no need for a mechanism for recognizing the difference in the developer or transferring information about the developer. It is not necessary to hold a large number of tables, and by simply calculating the viscosity characteristics with appropriate temperature correction according to each liquid developer, the concentration of the liquid developer can be adjusted easily and accurately. be able to.

  Further, by performing the density adjustment in this way, also in the image forming apparatus according to the present invention, the density of the collected developer can be easily and accurately adjusted and reused efficiently.

  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 unit will be described with reference to FIG. 1, and a liquid developing device (see FIG. 2) for reusing the collected developer and a developer concentration adjusting device used there. The configuration and functional operation will be described (see FIG. 3).

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

  In FIG. 1, reference numeral 1 denotes a photosensitive drum, which functions as an image carrier. The image forming unit 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, a transfer device 5 for transferring the developed toner image to a transfer material 7, A cleaning device 6 for removing the liquid developer remaining on the surface of the photosensitive drum after transfer is provided.

  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 it can be taken.

  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 this embodiment, the collected developer is reused, so that such a container is not necessary and the developer can be effectively used.

  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 unit 54, and a second supply unit 55.

  The first supply unit 54 contains, for example, a liquid developer having a concentration higher than a desired concentration as the first supply developer, and supplies the developer concentration measurement unit 50 in response to a supply signal.

  The second replenishment unit 55 stores, 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 agent concentration measuring unit 50 is replenished.

  The first supply unit 54 and the second supply unit 55 function as supply means.

  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 viscosity characteristic value, that is, 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 viscosity characteristic 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.

<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 measurement unit 50 includes a density adjustment tank 51, a discharged developer tank 52, a control unit 61, a stirring member 62, a driving device 63, a load detection device 64, a temperature detection device 65, and a storage unit 66.

  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.

  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 viscosity characteristic value corresponding to the viscosity of the liquid developer. Viscosity depends on concentration. That is, the load detection device 64 functions as a viscosity measuring unit.

  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. Here, the measured current value is a viscosity characteristic value representative of viscosity.

  The temperature detection device 65 is, for example, a temperature sensor, and is a device that is installed in the concentration adjustment tank 51 and detects the liquid temperature of the developer for concentration adjustment. That is, the temperature detection device 65 functions as a liquid temperature detection unit. The acquired liquid temperature of the developer for density adjustment is sent to the control unit 61 and used for temperature correction of the viscosity characteristic value.

  The storage unit 66 holds a reference correction table for correcting the temperature of the viscosity characteristic value. Also, a unique correction table created based on the reference correction table is stored. These are referred to or created and stored by the control unit 61. The storage unit 66 functions as a correction table storage unit.

  The controller 61 controls the operation of these components to obtain the density value of the density adjusting developer or the current value corresponding to the density, that is, the viscosity characteristic value. Further, based on the acquired viscosity characteristic value and liquid temperature, the above-described reference correction table is calibrated to create a unique correction table. That is, it functions as correction table calibration means.

  The control unit 61 controls the replenishment operation of the replenishing means for adjusting the concentration based on the comparison with the desired concentration (or the target viscosity characteristic value corresponding to the desired concentration). That is, the control unit 61 functions as a density adjusting unit.

  In addition, the control unit 61 creates a unique correction table for temperature correction (at the time of calibration), calculates and compares the target viscosity characteristic value (at the time of measurement), and the like. Details of these will be described later.

(Density measuring mechanism of developer density measuring unit)
The configuration of the developer concentration measuring unit 50 described above is such that the load detection device 64 detects the motor current value as a load when the developer for concentration adjustment is stirred using the stirring blade 62 as the viscosity characteristic, and the density is thereby detected. This is a configuration for calculating. 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.

  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.

  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 the amount of liquid at the time of overflow varies depending on the viscosity.

  As can be seen with reference to FIG. 4, the developer liquid is moved outward by centrifugal force by 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 of always controlling the amount of liquid at the time of stirring 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.

<Temperature correction of current value as viscosity characteristics>
As described above, measuring the current value of a motor used for driving a stirring blade or the like as a viscosity characteristic has been described. The stirring blade may be rotated at a predetermined rotational speed, and the current value at that time may be measured with an ammeter.

  A motor current value (viscosity characteristic value) as a load of stirring for a developer having a desired density is acquired in advance and set as a target current value (target viscosity characteristic 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. do it.

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

  However, in practice, the motor current value varies considerably depending on the liquid temperature of the liquid developer to be stirred. This is because the viscosity itself varies depending on the liquid temperature even though the concentration of the liquid developer does not change.

  FIG. 5A shows the relationship between the liquid temperature and the viscosity of the liquid developer. The viscosity changes as the liquid temperature increases.

  FIG. 5B shows the relationship between the liquid temperature and the current value (viscosity characteristics) for a liquid developer having a desired concentration (hereinafter referred to as a reference developer). The current value as the viscosity characteristic is a characteristic value representative of the viscosity, and therefore FIG. 5 (b) shows the same tendency as FIG. 5 (a).

  For this reason, the target current value held for the above density adjustment becomes inappropriate in some cases, or the measured current value is not appropriate if the view is changed. In other words, if the liquid temperature is different between when the target current value is set and when the current is measured, it is necessary to correct any of them to provide consistency.

  In order to correct the change in the liquid temperature of the liquid developer, it is only necessary to quantitatively grasp how the current value changes due to the change. For example, a relationship as shown in FIG. 5B is obtained in advance and a correction table is prepared. In actual measurement, the temperature of the density adjusting liquid developer is measured, and the current value at the liquid temperature is set to the target current value by referring to the correction table.

  However, the relationship between the liquid temperature and the current value (viscosity characteristic value) as shown in FIG. 5B changes as the type of developer changes. Therefore, it is necessary to change the correction table whenever the developer changes.

  FIG. 6A is a graph showing the relationship between liquid temperature and viscosity for various solutions. The types of liquids are different types of carrier liquids in P40, P70, P120, and P500, and the two types of developer are toners mixed in the same P70 carrier liquid.

  As shown in FIG. 6A, correction cannot be performed unless a different correction table is prepared for each liquid.

  FIG. 6B is a graph obtained by standardizing each relationship of FIG. 6A so that the liquid temperature is 25 ° C. In FIG. 6B, graphs with different types of carrier liquids do not overlap, but graphs of only two types of developer and carrier liquid P70 without toner overlap.

  In other words, it cannot be applied when the type of the carrier liquid is changed, but when the same carrier liquid is used, the relationship between the viscosity and the liquid temperature is proportional.

  In other words, the relational expression between the liquid temperature and the viscosity, viscosity = f (liquid temperature), can be approximated by viscosity′≈a × f (liquid temperature) when the developer is different (a is a constant determined by the developer). This relationship can be approximated when the solvent is constant and only the type of toner changes, such as a liquid developer.

  The developer has physical properties that change depending on manufacturing conditions. In particular, the toner varies depending on the resin material, particle size, dispersion state, pigment, and the like, even if the toner is manufactured in the same manner. On the other hand, there is usually little variation with respect to the carrier liquid. For this reason, fluctuations in the production of the developer hardly change in the carrier, and only the toner fluctuates. Therefore, the above proportional relationship can be applied to the variation in the production of the liquid developer.

  Next, let's consider the difference in measurement equipment and conditions.

  FIG. 7A is a graph showing the relationship between the viscosity of the liquid and the motor current value (viscosity characteristic value) during stirring. Measuring instruments 1 and 2 have different measuring devices and conditions. FIG. 7B is a graph in which the current values in FIG. 7A are normalized by current values at the minimum viscosity.

  As shown in FIG. 7A, the current value is substantially proportional to the viscosity. Moreover, when FIG.7 (b) was seen, the graph of the measuring devices 1 and 2 overlapped. That is, even when the apparatus and conditions are different, the relationship between the current value and the viscosity is proportional.

  That is, the relationship between the viscosity and the current value (viscosity characteristic value), the current value = g (viscosity), can be approximated by a current value '≈b × g (viscosity) when the device is different (b is a device-specific constant) .

  Here, the relationship between the liquid temperature and the viscosity and the relationship between the viscosity and the current value described above are summarized as follows.

  The relational expression between the liquid temperature and the current value, the current value = h (liquid temperature) is the current value '≈a × b × h (liquid temperature) = C × h (liquid temperature) when the developer and the apparatus are different. Can be approximated. The constant C is a combination of both the toner correction and the correction coefficient of the measuring device.

  Based on this relationship, temperature correction is performed using a correction table. Details of the temperature correction table will be described below.

(About temperature correction table)
The temperature correction described above is corrected using a correction table.

  As already described, the density adjustment is performed by comparing the viscosity characteristic value with a target viscosity characteristic value corresponding to a liquid developer having a desired density. The target viscosity characteristic value is corrected and set to the target viscosity characteristic value at the same temperature as the liquid temperature measured during the concentration adjustment using the correction table.

  The correction table is created in advance using the reference developer, but is calibrated with the developer and re-created with the developer in consideration of the variation of the developer and the device. However, the calibration can be made by simply converting the developer having a desired density at the temperature at that time point and obtaining a viscosity characteristic value by using the above-described proportional relationship.

  The procedure is as follows.

1. Standard correction table creation For example, when a device is shipped from the factory, using a common device and a common reference developer, a common reference correction table (indicating the relationship between the liquid temperature and the reference current value) is created in advance. Each device holds data. This shows the relational expression between the liquid temperature and the current value for the reference developer described above, and the reference current value = h (liquid temperature). This is the basis for creating the unique reference table by performing the next calibration in each device.

2. Calibration and creation of unique correction table Calibration is performed using the predetermined liquid developer at an appropriate timing in each apparatus, for example, when the developer cartridge is replaced. Calibration involves measuring the liquid temperature and current with a combination of a specific device and a specific developer. By referring to the data in the specific standard table, the specific constants are calculated and specific to the data in the specific standard table. Multiply a constant to create a unique correction table.

  The intrinsic constant is a relational expression in the case where the developer and the apparatus described above are different, and is C in the current value '≈C × h (liquid temperature), where C = current value during calibration' / h (liquid during calibration) Temperature). By applying this to a reference table (indicating current value = h (liquid temperature)), an inherent correction table (target current value = C × h (liquid temperature)) can be obtained.

3. Temperature correction processing for concentration adjustment The current value and liquid temperature are measured during concentration adjustment, the target current value corrected with the liquid temperature is obtained from the inherent correction table, and the measured current value is compared with the corrected target current value. Adjust the density.

  As the target current value, the target current value corrected for each liquid temperature at that time can be obtained using the inherent correction table indicating the above-described target current value = C × h (liquid temperature).

  FIG. 8A shows a graph in which the relational expression between the liquid temperature and the current value is measured for different types of developers. This relationship becomes the reference correction table for the reference developer.

  FIG. 8B is a diagram in which the relationship between the developers in FIG. 8A is normalized according to the reference correction table with the liquid temperature at the time of calibration. Here, each developer was adjusted to the reference developer at a calibration liquid temperature of 25 ° C. That is, the reciprocal number of each intrinsic constant C is multiplied to the relational expression of each developer.

  The relational expression of each developer almost coincides with the relational expression of the reference developer. That is, conversely, by applying an intrinsic constant to the reference correction table and creating the intrinsic correction table, the relationship between the target current value of the developer and the liquid temperature can be obtained appropriately.

  Hereinafter, a detailed procedure for temperature correction using the correction table in the density adjustment processing will be described.

<Create standard correction table>
FIG. 9 is a flowchart showing the procedure of the reference correction table creation process. The flow of the reference correction table creation process will be described with reference to FIG.

  First, in step S11, a reference measuring device and a developer having a desired density as a reference (a toner density of 25% in this embodiment) are prepared. By using this as a combination of the reference device and the reference developer, a reference correction table is created below.

  In step S12, a liquid developer (reference developer) having a desired toner concentration is put into a reference apparatus.

  In step S13, the liquid temperature of the reference developer is measured while changing the liquid temperature. At the same time, the reference developer is stirred, and the motor current value (viscosity characteristic value) corresponding to each measured liquid temperature is measured.

  In step S14, a reference correction table showing the relationship between the measured liquid temperature and the viscosity characteristic value (reference viscosity characteristic value) is created. This shows the relational expression between the liquid temperature and the current value described above, and the current value = h (liquid temperature).

  In step S15, the created reference correction table is stored in the storage unit of each device (developer concentration adjusting device).

  This completes the process of creating the reference correction table.

<Calibration and creation of unique correction table>
FIG. 10 is a flowchart showing a procedure of calibration performed for each apparatus (developer concentration adjusting apparatus), that is, a unique correction table creation process unique to each apparatus. FIG. 11 is a diagram showing a control operation of a specific correction table creation process as calibration. With reference to FIGS. 10 and 11, the flow of the specific correction table creation process as calibration will be described.

  First, in step S21, a measuring device and a developer having a desired density are prepared. A specific correction table is created by using this as a combination of a specific device and a specific developer. Therefore, the prepared measuring device is the developer concentration adjusting device itself used for density adjustment, and the developer having a desired concentration is the developer itself used in the device. By using a new developer to be newly set, a developer having a desired concentration can be secured.

  In step S22, a liquid developer having a desired toner concentration (25%) to be used is placed in an apparatus used for density adjustment (developer density adjusting apparatus 50). In an actual image forming apparatus, a mechanism may be provided in which unused liquid developer is set during calibration.

  In step S23, the temperature of the developer is measured by the temperature detecting device 65 (liquid temperature measuring step). At the same time, the developer is stirred at the liquid temperature, and the motor current value (viscosity characteristic value) is measured by the load detection device 64 (viscosity measurement step). The liquid temperature at this time is referred to as “calibration liquid temperature”, and the current value is referred to as “calibration current value”.

  In step S <b> 24, the calibration liquid temperature and calibration current value acquired by the control unit 61 are stored in the storage unit 66.

  In step S25, the control unit 61 refers to the reference correction table in the storage unit 66 and reads the reference current value corresponding to the liquid temperature during calibration. This is called “calibration reference current value”. The control unit 61 stores the read calibration reference current value in the storage unit 66.

  In step S26, the control unit 61 calculates a unique constant used for creating a unique table. The calculation formula is: intrinsic constant = calibration current value / calibration reference current value.

  In step S27, the control unit 61 reads the reference correction table from the storage unit 66, and multiplies the reference current value at each liquid temperature by a specific constant to obtain a target current value, and the relationship between the liquid temperature and the target current value. A unique correction table indicating the above is created. The unique correction table is stored in the storage unit 66.

  This completes the calibration, that is, the process for creating the unique correction table (correction table calibration process).

<Temperature correction processing for density adjustment>
FIG. 12 is a flowchart showing a procedure of temperature correction processing for density adjustment performed for each developer density adjusting device. FIG. 13 is a diagram showing a control operation of temperature correction processing for density adjustment. A flow of temperature correction processing for density adjustment will be described with reference to FIGS.

  First, in step S31, the collected developer from the developing device is put into the apparatus. As described above, the concentration of the collected developer varies, and this is the liquid developer whose density is to be adjusted.

  In step S32, the liquid temperature of the developer is measured by the temperature detection device 65 (liquid temperature measuring step). At the same time, the developer is stirred at the liquid temperature, and the motor current value (viscosity characteristic value) is measured by the load detection device 64 (viscosity measurement step). This is called a “measurement current value”. The control unit 61 acquires the measured liquid temperature and the measured current value.

  In step S33, the control unit 61 refers to the specific correction table in the storage unit 66, and reads out the target current value corresponding to the liquid temperature, that is, the temperature-corrected target current value. The control unit 61 stores the read target current value in the storage unit 66.

  In step S34, the control unit 61 compares the measured current value with the target current value. If the measured current value is equal to the target current value (or is within a preset target current value allowable range) (step S34: YES), it is not necessary to adjust the density, and the process proceeds to step S38 to end the density adjustment. Perform the process. The collected developer density adjustment process itself ends.

  When the measured current value is different from the target current value (or outside the preset target current value allowable range) (step S34: NO), the next step S35 is executed.

  In step S35, it is determined whether or not the measured current value is larger than the target current value. If the measured current value is larger than the target current value (step S35: YES), step S36 is executed. When the measured current value is smaller than the target current value (step S35: NO), step S37 is executed.

  In step S36, since the measured current value is larger than the target current value, that is, the viscosity is high and the concentration is higher than the target concentration (25%), the control unit 61 sends a supply signal to the second supply unit 55, The replenishment developer (low concentration liquid developer (including carrier liquid only)) is replenished to the collected developer in the apparatus.

  In step S37, since the measured current value is smaller than the target current value, that is, the viscosity is low and the concentration is lower than the target concentration (25%), the control unit 61 sends a replenishment signal to the first replenishment unit 54, The supplied developer (high concentration liquid developer) is supplied to the collected developer in the apparatus.

  When the replenishment process of step S36 or step S37 ends, the process returns to step S32, and in step S34, the measured current value becomes equal to the target current value (or falls within a preset target current value allowable range), and the process proceeds to step S38. Repeat the above steps until

  In step S38, the concentration of the collected developer has already been adjusted, and the density adjustment end process is performed. For example, the adjusted recovered developer is supplied to the developer tank 44. Further, for example, a new recovered developer is supplied from the recovered developer tank 53 to the developer concentration adjusting device 50, and the next density adjustment processing is repeated.

  This is the end of the density adjustment process (density adjustment process) including the temperature correction process.

  As described above, according to the present embodiment, in order to adjust the concentration of the liquid developer, the viscosity characteristic is used as the density substitute characteristic, and the adjustment to the target viscosity characteristic is performed as follows. Can do.

  In other words, in order to correct the target viscosity characteristic by the liquid temperature, a reference correction table that is determined and held in advance is calibrated to create a unique correction table. Based on the inherent correction table, the target viscosity characteristic corrected at the measured temperature is compared with the measured viscosity characteristic, and an adjustment is made to make the measured viscosity characteristic larger or smaller.

  As a result, even when the toner of the liquid developer is slightly different or there is a lot fluctuation of the toner, there is no need for a mechanism for recognizing the difference in the developer or transferring information about the developer. It is not necessary to hold a large number of tables, and by simply calculating the viscosity characteristics with appropriate temperature correction according to each liquid developer, the concentration of the liquid developer can be adjusted easily and accurately. be able to.

  Further, by performing the density adjustment in this way, also in the image forming apparatus according to the present invention, the density of the collected developer can be easily and accurately adjusted and reused efficiently.

  The scope of the present invention is not limited to the above embodiment. Unless it deviates from the meaning of this invention, those changed forms are also included in the range.

1 is a cross-sectional view illustrating a schematic configuration example of an image forming unit 10 of an image forming apparatus 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. (A) It is a graph which shows the relationship between the liquid temperature of a liquid developer, and a viscosity, and the relationship between the liquid temperature about a reference developer, and an electric current value (viscosity characteristic). (A) The graph which shows the relationship between the liquid temperature about various solutions, and a viscosity, (b) It is the graph which normalized them. (A) It is the graph which shows the relationship between the viscosity of a liquid, and the motor electric current value (viscosity characteristic value) at the time of stirring, (b) It is the graph which normalized them with the electric current value at the time of minimum viscosity. (A) For different types of developers, a graph in which the relational expression between the liquid temperature and the current value was measured, and (b) the relationship between these developers was standardized according to the reference correction table with the liquid temperature at the time of calibration. It is a graph. It is a flowchart which shows the procedure of a reference | standard correction table preparation process. It is a flowchart which shows the procedure of the calibration performed for every apparatus, ie, the specific correction table creation process peculiar to each apparatus. It is a figure which shows the control operation | movement of the specific correction table preparation process as calibration. It is a flowchart which shows the procedure of the temperature correction process for density adjustment performed for every apparatus. It is a figure which shows the control operation | movement of the temperature correction process for density adjustment.

Explanation of symbols

1 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 2 Charging apparatus 3 Exposure apparatus 4 Liquid developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Transfer material 8 Liquid developer 10 Image forming part 41 Developing roller (developer carrier)
42 Conveying roller 43 Supply roller 44 Developer tank 45 Regulating 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 section (high concentration developer) Supply means)
55 Second supply section (low density developer supply means)
60 Developer concentration adjusting device 61 Control unit (density adjusting means, correction table calibration means)
62 Stirring member (stirring blade)
63 Drive unit (motor)
64 Load detector (viscosity measuring means)
65 Temperature detection device (liquid temperature detection means)
66 Storage section (correction table storage means)
81 Liquid level during stirring of developer for density adjustment

Claims (9)

A developer concentration adjusting device for adjusting a toner concentration of a liquid developer in which toner is dispersed in a carrier liquid, using a change in viscosity of the liquid developer as an index,
Viscosity measuring means for measuring a viscosity characteristic value indicating the viscosity of the liquid developer;
A liquid temperature measuring means for measuring a liquid temperature of the liquid developer;
A correction table storage means for storing a first reference correction table obtained in advance showing the relationship between the criteria viscosity characteristic value and liquid temperature Metropolitan of liquid developer having a first concentration,
Wherein for the first of the second liquid developer which is the concentration, and the viscosity characteristic value and liquid temperature measured by the liquid temperature measuring means and said viscosity measuring means, said corresponding to a liquid temperature that is the measurement Correction for creating a specific correction table indicating the relationship between the target viscosity characteristic value and the liquid temperature for the second liquid developer by correcting the reference correction table based on the viscosity characteristic value in the reference correction table Table calibration means;
The viscosity characteristic value and the liquid temperature are measured for the liquid developer that is the target of density adjustment, and the measured viscosity characteristic value is based on the target viscosity characteristic value corresponding to the measured liquid temperature in the specific correction table . and a concentration adjusting unit for performing the toner density adjustment of the liquid developer so as to be equal to the target viscosity characteristic value, developer concentration adjusting device. The correction table calibration means includes
The ratio of the measured viscosity characteristic value to the reference viscosity characteristic value at the liquid temperature at which the liquid developer having the target toner concentration is newly measured is defined as an intrinsic constant.
For each reference viscosity characteristic value for each liquid temperature of the reference correction table, respectively Rukoto be manually corrected sieved uniform the unique constant, to create the unique correction table, developer density according to 請 Motomeko 1 Adjustment device. To the liquid developer to perform density adjustment, further comprising a replenishing means for replenishing one of the replenishment developer for a plurality of density adjustment of different toner concentrations,
The density adjusting means includes
The supply of the replenishment developer by the replenishing means is controlled so that the measured viscosity characteristic value is equal to the target viscosity characteristic value corrected for the liquid temperature, and the toner concentration of the liquid developer is equal to the target toner concentration. so as to adjust, developer concentration adjusting device according to 請 Motomeko 1 or 2. Is measured by the viscosity measuring means, the viscosity characteristic value representing the viscosity of the liquid developer is a motor current value as a load for agitating the liquid developer, in any one of 請 Motomeko 1 to 3 The developer concentration adjusting device as described. A developer concentration adjusting method for adjusting a toner concentration of a liquid developer in which toner is dispersed in a carrier liquid, using a change in viscosity of the liquid developer as an index,
A viscosity measuring step of measuring the viscosity characteristic value indicating the viscosity of the liquid body developer,
A liquid temperature measuring step of measuring the liquid temperature of the liquid body developer,
First the first reference correction table obtained in advance showing the relationship between the criteria viscosity characteristic value and liquid temperature Metropolitan of liquid developer having a concentration, said first concentration has been that the second liquid developer a viscosity characteristic value and liquid temperature measured in the previous SL viscosity measurement step and the liquid temperature measurement step for agents, based on the viscosity characteristic values in the reference correction table corresponding to the measured liquid temperature, modifies Thus, a correction table calibration step for creating a specific correction table indicating the relationship between the target viscosity characteristic value and the liquid temperature for the second liquid developer ,
The viscosity characteristic value and the liquid temperature are measured for the liquid developer that is the target of density adjustment, and the measured viscosity characteristic value is based on the target viscosity characteristic value corresponding to the measured liquid temperature in the specific correction table . and a concentration adjustment step for toner density adjustment of the liquid developer so as to be equal to the target viscosity characteristic value, developer density adjustment method. In the correction table calibration step,
The ratio of the measured viscosity characteristic value to the reference viscosity characteristic value at the liquid temperature at which the liquid developer having the target toner concentration is newly measured is defined as an intrinsic constant.
For each reference viscosity characteristic value for each liquid temperature of the reference correction table, respectively Rukoto be manually corrected sieved uniform the unique constant, to create the unique correction table, the developer concentration adjustment according to claim 5 Method. To the liquid developer to perform density adjustment, further comprising a replenishing step for replenishing one of the replenishment developer for a plurality of density adjustment of different toner concentrations,
The concentration adjusting step
The supply of the replenishment developer in the replenishment step is controlled so that the measured viscosity characteristic value is equal to the target viscosity characteristic value corrected for the liquid temperature, and the toner concentration of the liquid developer is equal to the target toner concentration. so as to adjust, developer density adjustment method according to claim 5 or 6. In the viscosity measuring step viscosity characteristic value indicating the viscosity of the liquid developer is a motor current value as a load for agitating the liquid developer, a developing according to any one of 請 Motomeko 5-7 Agent concentration adjustment method. An image carrier that forms a latent image on the surface;
The latent image on the surface of the image bearing member is developed with a liquid developer, an image forming apparatus having a liquid developing device for forming a toner image,
The developer concentration adjusting device according to any one of claims 1 to 4,
The developer desired the liquid developer is adjusted to the developer density by the concentration adjusting device, supplied to the liquid developing device, images forming device.

Images