JPH1115282A - Liquid developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the concn. of a liquid developer used for actual development. SOLUTION: When an electrostatic latent image formed on a photoreceptor drum is made visualizable by a developing means, a developer coating means forms a thin liquid developer layer being of the liquid developer and having a uniform thickness, on a revolving developing belt 11. The thin liquid developer layer formed in a transparent region except a developing region on the belt 11 is irradiated with light by the light emitting element 19 of a transmittance measuring means 17. A light receiving element 20 detects the intensity of the light after passing through the thin liquid developer layer and the transparent region of the belt 11, to transmit the intensity to the concentration calculating part of a concentration arithmetic part. The concentration calculating part calculates the concentration of the thin liquid developer layer from the transmitted intensity of the light after passing through and the characteristics of the concn. of the liquid developer and light transmittance which are stored in a characteristic storage part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developing apparatus for visualizing an electrostatic latent image formed by an electrophotographic system, electrostatic recording, an ion flow method or the like by using a liquid developer, and more particularly, to a developing method for developing a latent image. It is about the conversion.

[0002]

2. Description of the Related Art An image forming apparatus for visualizing an electrostatic latent image using a high-viscosity, high-concentration liquid developer is disclosed in, for example, Japanese Patent Application Laid-Open No.
This is disclosed in, for example, Japanese Patent No. 334001 and Japanese Patent Application Laid-Open No. 8-123205. In this image forming apparatus, as shown in FIG. 7, the photosensitive drum 1 is uniformly charged by the charger 2 and then exposed by the writing means 3 to form an electrostatic latent image. After applying a pre-wetting liquid having a releasable property and a chemically inert dielectric property to a uniform thickness on the photosensitive drum 1 on which the electrostatic latent image has been formed by the pre-wetting liquid applying means 4. The electrostatic latent image is visualized by the developing unit 500.

The developing means 500 is a high-viscosity liquid developer in which toner, which is visualized particles, is dispersed at a high concentration in a developer solvent made of an insulating liquid such as dimethylpolysiloxane oil. The liquid developer discharged from the supply pump 501 is applied with a uniform thickness to the developing belt 503 via a plurality of conveying rollers 502 to form a thin layer of the liquid developer. Developing belt 503
When the thin layer of the liquid developer applied to the photosensitive drum 1 passes through the developing area in the vicinity of the photosensitive drum 1, the toner of the thin liquid developer transfers to the image area of the photosensitive drum 1 to form a toner image. . The toner image formed on the photosensitive drum 1 is transferred to a transfer unit 6.
Is transferred to the transfer paper 8, and the residual toner on the photosensitive drum 1 after the transfer step is removed by the cleaning unit 7.

[0004]

In order to form a high-quality image with this image forming apparatus, it is necessary to uniformly apply a liquid developer to a developing belt of a developing means.
It is necessary to keep the concentration of the liquid developer, which is the ratio of the toner that is the visualized particles to the solvent of the developer, appropriate and to keep it constant. For this purpose, it is necessary to accurately detect the concentration of the liquid developer used.

SUMMARY OF THE INVENTION The present invention has been made to meet such a demand, and has as its object to provide a liquid developing apparatus capable of accurately detecting the concentration of a liquid developer used in actual development. It is.

[0006]

A liquid developing apparatus according to the present invention includes an electrostatic latent image formed on an image carrier in a high-concentration liquid developer applied in a thin layer on the developer carrier. A developer carrier that is visualized by visualized particles, at least a portion of which is formed of a transparent material, and a liquid developer that is applied in a thin layer to a portion of the developer carrier that is formed of a transparent material. Transmittance measuring means for measuring the light transmittance of the developer, and calculating the concentration of the liquid developer from the characteristics of the light transmittance measured by the transmittance measuring means and a predetermined liquid developer concentration and light transmittance. And a density calculating means.

Preferably, the transmittance measuring means is provided upstream of a developing position where the developer carrier contacts the image carrier. Further, it is desirable to provide the transmittance measuring means at a plurality of different places.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing means of the present invention comprises a developing belt wound around a plurality of rotating rollers, a developer storage tank, a developer applying means, a cleaning blade, a developer collecting section, a transmittance measuring means, and It has a density calculator. The developing belt is formed of a transparent conductive material on both sides of a developing area for developing an electrostatic latent image on the photosensitive drum, for example, ITO (indium tin oxide) or a transparent conductive plastic used as a transparent electrode. Have been. A potential between the minimum value and the maximum value of the latent image potential on the photosensitive drum is applied to the developing belt. The developer storage tank stores a high-viscosity liquid developer in which toner is dispersed in an insulating liquid. The developer applying unit applies the liquid developer to the developing belt to form a thin liquid developer layer having a uniform thickness on the surface of the developing belt. The cleaning blade removes the liquid developer remaining on the developing belt after the developing process. The developer collecting section collects the removed liquid developer in a developer applying unit. The transmittance measuring means is provided in the middle of the position where the developer applying means and the developing belt are in contact with the photosensitive drum, and has a light emitting element and a light receiving element provided with a transparent region at an end of the developing belt interposed therebetween. The density calculation unit includes a density calculation unit, a characteristic storage unit storing characteristics of the liquid developer and light transmittance measured in advance, and an output unit.

When the developing means develops and visualizes the electrostatic latent image formed on the photosensitive drum, the developer applying means applies a liquid developer of a uniform thickness to the rotating developing belt. A thin agent layer is formed. When the electrostatic latent image formed on the photoreceptor drum is visualized by the liquid developer thin layer having a uniform thickness formed on the developing belt, the light emitting element of the transmittance measuring unit is other than the developing area of the developing belt. The light is applied to the liquid developer thin layer formed in the transparent region of FIG. The light receiving element detects the intensity of light transmitted through the liquid developer thin layer formed in the transparent area other than the development area and the transparent area, and sends the detected light intensity to the density calculator of the density calculator. The density calculation unit calculates the density of the liquid developer thin layer from the transmitted light intensity, the density of the liquid developer stored in the characteristic storage unit, and the light transmittance characteristics. The output unit determines whether or not the concentration of the liquid developer calculated by the concentration calculation unit is within a specified range, and outputs the result.

Since the concentration of the liquid developer is detected from the transmitted light intensity of the liquid developer thin layer formed on the developing belt as described above, the concentration of the liquid developer actually used for development is accurately detected. be able to.

When detecting the concentration of the liquid developer,
The transmitted light intensity of the liquid developer thin layer formed on the developing belt is measured before developing the electrostatic latent image on the photosensitive drum, and is not affected by the developing process such as a pre-wet liquid applied to the photosensitive drum. Measure the concentration of the liquid developer.

When the transmitted light intensity of the liquid developer thin layer formed on the developing belt is measured at a plurality of locations, the concentration of the liquid developer actually used for development is not affected by the surface condition of the developing belt. And can be accurately detected.

[0013]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the figure, a charging unit 2, a pre-wet liquid applying unit 3, and a writing unit 4, which are disposed along a photoreceptor drum 1 rotating clockwise in an image forming / transferring unit of a wet image forming apparatus.
And a developing unit 5, a transfer unit 6, and a cleaning unit 7. After the photosensitive drum 1 is uniformly charged by the charger 2, the pre-wet liquid is applied by the pre-wet liquid applying means 3 with a uniform thickness. The photosensitive drum 1 coated with the pre-wet liquid is exposed by the writing means 4 to form an electrostatic latent image. The electrostatic latent image is visualized by the developing means 5 to form a toner image, and the formed toner image is transferred to the transfer paper 8 by the transfer means 6. The cleaning unit 7 removes residual toner on the photosensitive drum 1.

The developing means 5 includes a plurality of rotating rollers 10a to 10a.
A developing belt 11, a developer storage tank 12, and a developing roller applying means 13 having a coating roller 14; and a cleaning blade. 15, a developer recovery unit 16 and a transmittance measuring unit 17. Developing belt 11
Are areas 112 on both sides of a development area 111 for developing an electrostatic latent image on the photosensitive drum 1 as shown in the partial plan view of FIG.
Is formed of a transparent conductive material, for example, ITO (indium tin oxide) used as a transparent electrode or a transparent conductive plastic. A developing region 111 formed of a non-transparent ordinary belt in which carbon of the developing belt 11 is dispersed and a transparent region 11 made of, for example, ITO.
2 can be easily joined by fusion using ultrasonic waves. A potential between a minimum value and a maximum value of the latent image potential on the photosensitive drum 1 is applied to the developing belt 11 by a bias applying unit (not shown). Developer storage tank 1
2 is 100 to 1000 mP in which toner is dispersed in an insulating liquid.
The liquid developer 18 having a high viscosity of a · s is stored. The developer applying unit 13 applies the liquid developer 18 to the developing belt 11 to form a thin liquid developer layer having a uniform thickness on the surface of the developing belt 11.

The transmittance measuring means 17 includes a developer applying means 13
The developing belt 11 is provided at a position intermediate the position where the developing belt 11 comes into contact with the photosensitive drum 1, and as shown in the sectional view of FIG. It has an element 20. The light emitting element 19 irradiates light to the transparent region 112 of the developing belt 11 in the liquid developer thin layer 18 a having a uniform thickness formed on the surface of the developing belt 11. The light receiving element 20 is a thin liquid developer layer 18a.
And the intensity of the light transmitted through the transparent region 112 of the developing belt 11 is sent to the density calculator 22 of the density calculator 21 shown in the block diagram of FIG. The relationship between the concentration of the liquid developer, which is the ratio of the toner that is the visualized particles to the developer solvent of the liquid developer, and the light transmittance has a one-to-one relationship as shown in the characteristic diagram of FIG. As the weight ratio of the toner to the developer solvent decreases, the light transmittance increases. The density and light transmittance characteristics of the liquid developer are measured in advance and stored in the characteristic storage unit 23 of the density calculation unit 21. Density calculator 2
Reference numeral 2 denotes a liquid used at that time based on the intensity of light transmitted from the light-receiving element 20 and transmitted through the liquid developer thin layer 18a and the characteristics of the concentration and light transmittance of the liquid developer stored in the characteristic storage unit 23. The density of the developer 18, that is, the content of the toner is calculated.

When the developing means 5 configured as described above develops and visualizes the electrostatic latent image formed on the photosensitive drum 1, the developer applying means 13 rotates counterclockwise. A liquid developer thin layer 18 a having a uniform thickness of the liquid developer 18 is formed on the belt 11. The toner contained in the liquid developer thin layer 18 a having a uniform thickness formed on the developing belt 11 visualizes the electrostatic latent image on the photosensitive drum 1. When the electrostatic latent image on the photosensitive drum 1 is visualized, the toner adheres only to the image portion of the electrostatic latent image, and the developer solvent as a carrier adheres to the entire area of the photosensitive drum 1. The liquid developer 18 remaining on the developing belt 11 after this developing step is removed by the cleaning blade 15, and the removed liquid developer 18 is removed by the developer collecting unit 16 by the developer applying unit 13.
Will be collected.

The developer solvent in the liquid developer 18 collected by the developer application means 13 is always consumed in a constant amount in the developing process, while it fluctuates according to the area of the image to be developed by the toner. There is a possibility that the ratio, that is, the concentration, of the toner of the liquid developer 18 collected by the developer applying unit 13 with respect to the developer solvent is changed. For this reason, the ratio of the toner of the liquid developer 18 collected in the developer application unit 13 is adjusted by the liquid developer 18 in the developer storage tank 13. 1
In step 3, it is necessary to constantly check the ratio of the toner of the liquid developer 18 applied to the developing belt 11.

Therefore, when the electrostatic latent image is visualized by the liquid developer thin layer 18a having a uniform thickness formed on the developing belt 11, the light receiving element 20 of the transmittance measuring means 17 is connected to the liquid developer thin layer. 18a and the transparent area 112 other than the development area 111
Is detected and sent to the density calculator 22 of the density calculator 21. The density calculation unit 22 determines the intensity of the transmitted light transmitted from the light receiving element 20 and the density of the liquid developer stored in the characteristic storage unit 23 and the characteristics of the light transmittance.
The concentration of 8a is calculated. The output unit 24 determines whether the density of the liquid developer 16 calculated by the density calculation unit 22 is within a specified range, and outputs the result. Based on this output, the liquid developer 18 in the developer storage tank 13 adjusts the ratio of the toner of the liquid developer 18 to be applied to the developing belt 11 by the developer applying means 13.

As described above, since the concentration of the liquid developer 18 actually used for development is detected from the transmitted light intensity of the liquid developer thin layer 18a formed on the developing belt 11, it is actually used for development. The concentration of the liquid developer 18 can be accurately detected. Therefore, the detected liquid developer 1
8, the density of the liquid developer 18 used for development can be optimally adjusted, and a high-quality image can be stably formed.

When detecting the concentration of the liquid developer 18, the liquid developer thin layer 18 formed on the developing belt 11 is detected.
Since the transmitted light intensity a is measured before developing the electrostatic latent image on the photosensitive drum 1, the concentration of the liquid developer 18 can be reduced without being affected by the developing process such as a pre-wet liquid applied to the photosensitive drum 1. Measurement can be performed with high accuracy.

In the above embodiment, the case where the concentration of the liquid developer thin layer 18a formed on the developing belt 11 is measured at one location has been described. As shown in the sectional view of FIG. The liquid developer thin layer 18 formed on the developing belt 11 at two or more locations in the transparent area 112
The averaging process may be performed by measuring the density of a. By measuring and averaging the concentration of the liquid developer thin layer 18a formed on the developing belt 11 at two or a plurality of positions, the concentration of the liquid developer 18 actually used for development can be reduced. Detection can be performed accurately without being affected by the surface condition of the belt 11.

In the above embodiment, the case where the regions 112 on both sides of the developing region 111 of the developing belt 11 are formed of a transparent conductive material has been described, but the entire developing belt 11 is formed of a transparent conductive material. Is also good.

[0023]

According to the present invention, as described above, the concentration of the liquid developer is detected from the transmitted light intensity of the thin liquid developer layer formed on the developer carrier, so that the present invention is actually used for development. The concentration of the liquid developer can be accurately detected,
High quality images can be formed.

Further, when detecting the concentration of the liquid developer, the transmitted light intensity of the liquid developer thin layer formed on the developer carrier is measured before developing the electrostatic latent image on the photosensitive member.
The concentration of the liquid developer can be measured without being affected by a developing process such as a pre-wet liquid applied to the photoreceptor, and the concentration of the liquid developer can be accurately detected.

Further, the transmitted light intensity of the liquid developer thin layer formed on the developer carrier is measured at a plurality of locations and averaged, so that the concentration of the liquid developer actually used for development can be determined. The detection can be performed accurately without being affected by the surface condition of the agent carrier.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a plan view illustrating a configuration of a developing belt.

FIG. 3 is a sectional view showing an arrangement of transmittance measuring means.

FIG. 4 is a block diagram illustrating a configuration of a density calculation unit.

FIG. 5 is a characteristic diagram of density and light transmittance.

FIG. 6 is a sectional view showing an arrangement of a transmittance measuring means according to a second embodiment.

FIG. 7 is a configuration diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 5 developing means 11 developing belt 12 developer storage tank 13 developer applying means 15 cleaning blade 16 developer collecting unit 17 transmittance measuring means 18 liquid developer 19 light emitting element 20 light receiving element 21 density calculating unit 22 density calculation Unit 23 characteristic storage unit 24 output unit

Claims (3)

[Claims] 1. A liquid developing apparatus for visualizing an electrostatic latent image formed on an image carrier by visualized particles contained in a high-concentration liquid developer applied in a thin layer on a developer carrier. A transmittance for measuring a light transmittance of a developer carrier formed at least in part of a transparent material and a liquid developer applied in a thin layer on a portion of the developer carrier formed of a transparent material; Measuring means, and density calculating means for calculating the concentration of the liquid developer from the characteristics of the light transmittance measured by the transmittance measuring means and the predetermined concentration of the liquid developer and the light transmittance. Liquid developing device. 2. The liquid developing apparatus according to claim 1, wherein said transmittance measuring means is provided upstream of a developing position at which the developer carrier contacts the image carrier. 3. The liquid developing apparatus according to claim 2, wherein said transmittance measuring means is provided at a plurality of different places.