JP2001305867A - Concentration measuring unit for liquid toner and liquid developing electrophotographic device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means of measuring the solid particle concentration of the recovered toner in order to recycle the liquid toner. SOLUTION: According to the concentration measured by the concentration measuring unit, the concentration of the liquid toner in a toner container 44 is adjusted to the prescribed value by adding carrier solution and/or high concentration liquid toner through a concentration regulator. The adjusted liquid toner is supplied to a photoreceptor drum 10 through an applicator roller 41, 42 and a developing roller 40. The concentration measuring unit consists of a transparent tube, a toner applying roller for applying the liquid toner to the surface of the tube, a light emitting element equipped outside or inside of the tube and photo-accepting element equipped inside or outside of the tube. The amount of the transmitted light from the light emitting element is optically measured at the light receiving element and the solid content concentration of the liquid toner is determined from this.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-volatile, high-viscosity, high-concentration liquid toner concentration measuring apparatus and a liquid developing wet electrophotographic apparatus using the same.

[0002]

2. Description of the Related Art In an electrophotographic apparatus in which an electrostatic latent image is formed on a photosensitive member (photosensitive drum), toner is adhered to the image, and the image is transferred to paper and fixed, a dry type using powder toner is widely used. Used.

However, the powder toner has a problem that the toner is scattered, and the toner particles have a particle size of 7 to 10 μm.
There is a problem that the resolution is poor due to the large value of m.

Therefore, when high resolution is required, a wet type using a liquid toner is used. Liquid toner has toner particles as small as about 1 μm,
Due to the large charge amount, disturbance of the toner image hardly occurs,
This is because high resolution can be realized.

In a liquid developing type electrophotographic apparatus, when a non-volatile high-viscosity, high-concentration liquid toner is used as a developing solution, it is very convenient to provide a function of recycling the liquid toner. Becomes In general,
In a dry type electrophotographic apparatus using a powder toner, there is no idea of recycling the powder toner. This is because the powder toner is not diluted. That is, in a dry-type electrophotographic apparatus, the toner is supplied to the photoconductor by supplying powder toner to the developing roller while frictionally charging using a blade, and the development transferred to the photoconductor is performed. Only the process of supplying powder toner to the roller portion is performed.

On the other hand, in a liquid developing electrophotographic apparatus using a liquid toner, since the liquid toner is diluted, the idea of recycling the liquid toner comes up.

FIG. 9 illustrates a conventional configuration for collecting and reusing a developer (Japanese Patent Laid-Open No. 11-27283). In order to use liquid toner as liquid developer, 1
A thin layer of about 50 μm is applied on the developing roller 40 and sent to the developing gap. The liquid developer remaining on the developing roller 40 after passing through the developing gap portion is scraped off by the blade 45 and stored in the collecting portion 43. The liquid developing solution is diluted by moving the solid particles onto the photosensitive drum 10. , And also diluted by the incorporation of pre-wet oil.

The diluted liquid developer is sent to the toner reservoir 44 using a pump or the like. Here, high-density toner is supplied, mixed with the previous diluted toner,
A liquid toner having a predetermined density is obtained. The liquid toner having the predetermined concentration is supplied to the developing roller 40 while being thinly stretched from the toner reservoir 44 by an applicator constituted by the roller 41 and the roller 42, whereby the developing is performed.

However, the ratio of the solid particles of the liquid toner to be recovered is not constant. Typically, the consumption of solid particles varies based on the image data. In order to reuse the liquid toner, it is necessary to accurately grasp the ratio (concentration) of the solid particles of the liquid toner to be collected.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of a case where a configuration using a non-volatile, high-viscosity, high-concentration liquid toner is employed.
An object of the present invention is to provide a means for measuring a solid particle concentration of a collected liquid toner in order to realize a function of recycling a liquid toner.

It is another object of the present invention to correct the concentration based on the detected solid particle concentration of the liquid toner and supply the corrected toner to a photosensitive drum or a developing roller.

[0012]

According to the present invention, there is provided an apparatus for measuring the concentration of a liquid toner, comprising a transparent tube, a toner application roller for applying liquid toner to the surface of the tube, and an outside or inside of the tube. And a light-receiving element disposed inside or outside the tube. The amount of transmitted light from the light emitting element is optically measured by the light receiving element, whereby the solid content concentration of the liquid toner is measured.

[0013] Further, a light emitting / receiving element disposed in a tube is arranged, and the amount of light emitted from the light emitting / receiving element and reflected by the liquid toner layer is optically measured by the light emitting / receiving element. Can be.

Further, a pair of rollers contacting with a constant pressure, and an optical line sensor for reading a spread width of the liquid toner at a nip exit by supplying a fixed amount of toner between the pair of rollers. The density of the liquid toner can be determined based on the spread width of the liquid toner.

Further, according to the present invention, there is provided an apparatus for measuring the concentration of liquid toner, comprising: a metal roller having a step on both sides such that a concave portion is formed at the center of the tube; and an excessive amount of liquid toner applied to the surface of the metal roller. A blade for scraping things,
An elastic roller that rotates in contact with the metal roller.
By applying a bias voltage between the metal roller and the elastic roller and measuring the current flowing at that time, the concentration of the liquid toner can be determined.

Further, the liquid developing electrophotographic apparatus of the present invention comprises:
A means for providing a heater on the surface of a pipe for transporting liquid toner from the toner tank to the developing unit to maintain a constant temperature, a screw for transporting liquid toner in the pipe, and a motor for driving the screw; Is provided. By monitoring the current value or the number of rotations of the motor load, the concentration of the liquid toner can be determined.

Further, the liquid developing electrophotographic apparatus of the present invention comprises:
Means for forming a pattern for checking toner density on the image support, means for measuring a developing current flowing to the developing roller when the pattern is developed, and a predetermined value for the developing current. When the output of the comparing means and the output of the comparing means indicate a developing current smaller than the set value, a high-density toner is supplied, and the output of the comparing means outputs a developing current larger than the set value. When shown, it comprises a means for supplying a carrier liquid.

Further, the liquid developing electrophotographic apparatus of the present invention comprises:
A developing roller to which a liquid toner is supplied from the toner supply roller while applying a bias voltage to the toner supply roller;
Means for measuring a bias current flowing to the toner supply roller, means for comparing the bias current with a predetermined set value, and when the output of the comparison means indicates a bias current smaller than the set value, the toner The bias voltage applied to the toner supply roller is increased by increasing the bias voltage applied to the supply roller, and when the output of the comparison means indicates a bias current larger than the set value. Means for lowering the voltage to reduce the toner supply amount.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail according to embodiments. The liquid toner is obtained by dispersing toner particles such as a pigment in a liquid carrier (oil).

FIG. 1 is a diagram showing an overall configuration for collecting a liquid toner, measuring the density, adjusting the density, and reusing the toner. Although the liquid toner is illustrated as being collected from the developing roller 40, the liquid toner is not limited to the liquid toner collected from the developing roller 40, but may be a carrier liquid or a pre-wet liquid collected from a photosensitive drum or an intermediate transfer body. Can also be collected in the toner reservoir 44.

The illustrated density measuring apparatus is configured to measure the density after the density adjustment, but may be configured to measure the density of the collected liquid toner itself.
Based on the concentration measured by the concentration measuring device, a carrier liquid or a high-concentration liquid toner,
Alternatively, the density of the liquid toner in the toner reservoir 44 can be adjusted to a predetermined value by replenishing both of them. The liquid toner adjusted to the predetermined density is supplied to the photosensitive drum 10 via the applicator rollers 41 and 42 and the developing roller 40 as usual.

FIG. 2 is a diagram illustrating a first configuration of the concentration measuring device of the present invention. In the figure, liquid toner is thinly applied to the surface of a transparent tube by a toner application roller. A light-emitting element is arranged in a transparent tube, and a light-receiving element is arranged correspondingly outside the tube. Alternatively, the light emitting element and the light receiving element can be reversed. The solid content of the liquid toner is measured by optically measuring the amount of light emitted from the light emitting element through the transparent tube and the liquid toner layer by the light receiving element. Since the toner can be applied thinly, the density can be measured even with a high density toner. The illustrated blade is for scraping residual toner after measurement.

Further, a light receiving / emitting element can be arranged in the tube. After emitting light from the light emitting and receiving element, the amount of light reflected by the liquid toner layer is optically measured by the light emitting and receiving element to measure the solid content concentration of the liquid toner. By applying the toner thinly, it becomes possible to optically measure the density even with a high density toner. Further, it is possible to easily prevent the light emitting / receiving element from being stained by the liquid toner.

FIG. 3 shows an arrangement for making the layer thickness of the liquid toner applied to the surface of the transparent tube used in the first arrangement constant. The illustrated transparent tube has steps on both sides so that a concave portion is formed at the center of the tube. Further, a blade for scraping the liquid toner on the tube surface is provided. For this reason, the layer thickness of the liquid toner applied to the concave portion at the center of the tube is determined by the height of the step set to, for example, several μm and is constant.

FIG. 4 shows a second configuration for measuring the concentration of the liquid toner. As shown in the figure, a pair of rollers contacting with a constant pressure is provided, and a certain amount of liquid toner is injected between the pair of rollers. At this time, the spread width of the liquid toner at the nip outlet expands up to a predetermined number of rotations, but thereafter becomes substantially constant width, and the spread width at this time is substantially proportional to the solid concentration of the liquid toner. I have. Therefore, the density of the liquid toner can be determined by reading the spread width using an optical line sensor.

FIG. 5 shows a third configuration for measuring the concentration of the liquid toner. As shown in the figure, a metal roller having a step on both sides such that a concave portion is formed at the center of the tube is provided. Liquid toner is applied to the surface of the metal roller, but excess liquid toner is scraped off by a blade, so that the liquid toner on the surface of the metal roller can always have a constant layer thickness regardless of viscosity. . A conductive elastic (rubber) roller that rotates in contact with the metal roller is provided, a bias voltage is applied between the two rollers, and the current flowing at that time is measured to determine the concentration of the liquid toner. Can be. In addition, the current flowing from the metal surface other than the concave portion at the center of the tube to the conductive elastic roller without passing the liquid toner is corrected by insulating the metal roller surface to prevent it, or subtracting it from the measured value. can do.

FIG. 6 shows a fourth configuration for measuring the concentration of the liquid toner. As shown in the drawing, a heater is provided on the surface of a tube for transporting liquid toner from the toner tank to the developing unit, and a thermistor for detecting the temperature of the tube surface is provided so that the tube surface is maintained at a constant temperature. Is controlled. A screw for conveying the liquid toner in the tube and a DC motor for driving the screw are provided, and the motor load is monitored by a current value or a rotation speed. The concentration of the liquid toner can be determined based on the monitored motor load. This is a measurement method utilizing the fact that there is a correlation between the viscosity and the concentration of the liquid toner, but is controlled at a constant temperature so that the viscosity of the toner is not affected by the temperature.

FIG. 7 is a diagram illustrating a configuration for detecting the developing current and adjusting the density of the liquid toner. The liquid toner is applied as a thin layer of 1 to 50 μm on the developing roller 40 so as to be used as a liquid developing solution.
It is sent to the developing gap between zero. Developing roller 40
The liquid developer remaining on the top after passing through the development gap,
The solid particles are scraped off by the blade 45 and accumulated in the accumulation section 43. The solid particles are diluted by moving on the photosensitive drum 10 and further diluted by mixing of pre-wet oil.

The diluted liquid developer is sent to the toner reservoir 44 using a pump or the like. Here, a high-concentration liquid toner or a carrier liquid is supplied and mixed with the diluted toner to form a liquid toner having a predetermined concentration. The liquid toner having the predetermined concentration is supplied to the developing roller 40 from an applicator including the rollers 41 and 42.

At this time, whether or not the liquid toner has a predetermined density is detected by a bias current flowing through the developing roller. When the developing roller 40 is the photosensitive drum 10
When supplying the liquid toner by contacting the upper portion, a positive voltage of, for example, 400 V is applied as a bias voltage to the developing roller to adhere toner particles to an exposed portion of the photosensitive drum 10 charged to, for example, about 100 V. Is applied to
The bias current flowing at this time is affected by the amount of toner particles attached to the exposed portion.

In order to avoid the influence and to make the conditions equal, a pattern for checking toner density is selected as an image to be printed, and this pattern is formed on the photosensitive drum 10. The developing current (bias current) flowing to the developing roller when performing this developing is affected by the concentration of the liquid toner when the toner layer thickness is constant.

Therefore, when the developing current is compared with a preset value (Vr) predetermined in the comparator, if it is lower than that, it means that the density of the liquid toner is low. In such a case, it is configured to supply a high-concentration liquid toner.

Conversely, the developing current is compared with a predetermined set value (Vr) in the comparator. If the developing current is higher than the set value (Vr) (in the configuration shown in FIG. ), Which means that the concentration of the liquid toner is high, and in that case, the carrier liquid is supplied.

When the output of the comparator falls within a certain range, a device (not shown) for adjusting the toner layer thickness to the developing roller is provided so that a constant image density can be obtained. Can be For example, the developing roller 40
The thickness of the toner layer on the developing roller 40 is adjusted directly by adjusting the interval between the applicator rollers and the indirect amount by adjusting the interval between the applicator rollers 41 and 42 to adjust the supply amount. be able to.

When the output of the comparator falls within a certain range, a device (not shown) for adjusting the bias voltage V1 applied to the developing roller 40 is provided.
It is also possible to configure so as to obtain a constant image density.

Further, when supplying the liquid toner from the applicator roller 41 to the developing roller 40, the bias voltage (V2) can be applied. It is known that the amount of liquid toner moving from the applicator roller 41 to the developing roller 40 can be controlled by such a bias voltage. By applying a bias voltage, for example, 100 V higher than the bias voltage applied to the developing roller 40, it is possible to move most of the liquid toner toward the developing roller 40 at the contact portion between the developing roller 40 and the applicator roller 41. Will be possible.

Therefore, a voltage control device is provided which detects a bias current flowing through the applicator roller 41 and adjusts a bias voltage based on the bias current. A low bias current means that the liquid toner concentration is low. Therefore, when the bias current is smaller than the predetermined set value, the bias voltage applied to the applicator roller 41 is increased to increase the toner supply amount. Can be. Conversely, when the bias current indicates a value larger than a predetermined set value, the bias voltage applied to the applicator roller 41 can be reduced to reduce the toner supply amount.

The surface of the applicator roller 41 is
A configuration in which concave portions are provided in a mesh shape can be adopted. FIG. 8 is a diagram illustrating a surface configuration of such an applicator roller 41. As described above, in order to estimate the toner concentration from the bias current flowing through the applicator roller 41, it is desirable to keep the toner layer thickness, that is, the toner supply amount constant. As shown in the drawing, the toner supply amount can be kept constant by conveying and supplying the liquid toner while holding it in the concave portion.

Further, in order to estimate the toner concentration from the bias current, the bias current should be made to flow only through the liquid toner in the concave portion and not through the convex portion, or to be negligible even if it flows. Is desirable.
Therefore, it is desirable that the surface of the convex portion of the illustrated roller is coated with a urethane resin or the like to make it insulative.

[0040]

According to the present invention, in a liquid developing electrophotographic apparatus employing a non-volatile, high-viscosity, high-concentration liquid toner, in order to realize a function of recycling the liquid toner, the collected liquid toner is used. Allows the solid particle concentration to be measured.

Further, according to the present invention, based on the detected solid particle concentration of the liquid toner, the concentration can be corrected and supplied to the photosensitive drum or the developing roller.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration for collecting a liquid toner, measuring a density, adjusting a density, and reusing the toner.

FIG. 2 is a diagram illustrating a first configuration of a concentration measuring device of the present invention.

FIG. 3 is a diagram showing a configuration for making a layer thickness of a liquid toner applied to a surface of a transparent tube shown in FIG. 2 constant.

FIG. 4 is a diagram illustrating a second configuration for measuring the concentration of the liquid toner.

FIG. 5 is a diagram illustrating a third configuration for measuring the concentration of the liquid toner.

FIG. 6 is a diagram illustrating a fourth configuration for measuring the concentration of the liquid toner.

FIG. 7 is a diagram exemplifying a configuration for detecting the developing current and adjusting the concentration of the liquid toner.

FIG. 8 is a diagram illustrating a surface configuration of an applicator roller;

FIG. 9 is a diagram showing a conventional configuration for collecting and reusing a developer.

[Explanation of symbols]

 Reference Signs List 10 photosensitive drum 40 developing roller 41, 42 applicator roller 43 reservoir 44 toner reservoir 45 blade

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Uesugi 98 Unoki-nu, Unoki-cho, Hebei-gun, Ishikawa Pref. Address No. 2 PFU Co., Ltd. (72) Inventor Masanori Takahata 98 Uno-ki, Unoki-cho, Hebei-gun, Ishikawa Prefecture 98-2 In PFU Co., Ltd. 98-2 Inside PFU Co., Ltd. (72) Inventor Shigeharu Okano Unoki-ki, Unoki-cho, Hebei-gun, Ishikawa Prefecture 98-2 Inside PFU Co., Ltd. (72) Inventor Yasukazu Takeda Unoki, Unoki-cho, Kawakita-gun, Ishikawa No. 98 No. 2 Inside PFU Co., Ltd. (72) Inventor Tadashi Nishikawa Unoki 98, Unoki-cho, Kawakita-gun, Ishikawa (72) Inventor, Satoshi Miyamoto 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture 2 Inventor Kazushi Terashima 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa No.2 Inside PFU Co., Ltd. (72) Inventor Satoshi Sakai At 98 98 Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa Pref. Inside (72) Inventor Hironaga Motokawa Uno-nu, character at Unoki-cho, Kawakita-gun, Ishikawa 98-2 Inside PFU Co., Ltd. (72) Inventor Masanobu Motoe 98-2 Unoki-nu, Unoki-cho, Hebei-gun, Ishikawa Prefecture F-term within PFU Co., Ltd. F-term (reference) KK04 NN01 2G060 AA06 AE17 AF01 AG07 AG11 HB06 HC07 HC10 2H073 BA01 BA13 BA21 BA27 CA32 2H074 AA03 BB50 BB54 BB60 BB72 CC03 CC13 CC23 CC24 CC26 CC28 CC64

Claims (12)

[Claims] A transparent tube; a toner application roller for applying liquid toner to a surface of the tube; a light emitting element disposed outside or inside the tube; and a light emitting element disposed inside or outside the tube. A liquid toner concentration measuring device, comprising: a light receiving element; and measuring a solid content concentration of the liquid toner by optically measuring a transmitted light amount from the light emitting element with the light receiving element. 2. The transparent tube has a step on both sides so as to form a recess in the center of the tube, and has a blade for scraping liquid toner on the surface of the tube. 2. The liquid toner concentration measuring device according to claim 1, wherein the layer thickness of the liquid toner applied to the concave portion is constant. 3. A transparent tube, a toner application roller for applying liquid toner to a surface of the tube, and a light emitting / receiving element disposed in the tube, wherein the light emitting / receiving element emits light. A liquid toner concentration measuring device for measuring the solid content concentration of a liquid toner by optically measuring the amount of light reflected by the liquid toner layer with a light receiving / emitting element. And a pair of rollers that are in contact with each other under a predetermined pressure, and an optical line sensor that inputs a predetermined amount of toner between the pair of rollers and reads a spread width of the liquid toner at an outlet of the nip. A liquid toner concentration measuring device for determining the concentration of the liquid toner based on the spread width of the liquid toner. 5. A metal roller having steps on both sides such that a concave portion is formed at the center of the tube, a blade for scraping off excess liquid toner applied to the surface of the metal roller, and An elastic roller that rotates in contact with the metal roller, a bias voltage is applied between the metal roller and the elastic roller, and a current flowing at that time is measured to determine a density of the liquid toner. measuring device. 6. A liquid developing electrophotographic apparatus using a non-volatile high-viscosity liquid toner in which toner particles are dispersed at a predetermined concentration in a liquid carrier as a liquid developing solution, wherein the liquid toner is transferred from a toner tank to a developing unit. A means for maintaining a constant temperature by providing a heater on the surface of the pipe for transport, a screw for transporting the liquid toner in the pipe, and a motor for driving the screw; Or a liquid developing electrophotographic apparatus comprising determining the concentration of the liquid toner by monitoring the number of rotations. 7. A liquid developing electrophotographic apparatus using a non-volatile high-viscosity liquid toner in which toner particles are dispersed at a predetermined concentration in a liquid carrier as a liquid developing solution. Means for forming a pattern, means for measuring a developing current flowing through a developing roller when the pattern is developed, means for comparing the developing current with a predetermined set value, and When the output indicates a developing current smaller than the set value, a high-density toner is supplied. When the output of the comparing means indicates a developing current larger than the set value, a carrier liquid is supplied. Liquid developing electrophotographic apparatus comprising: 8. The image forming apparatus according to claim 7, wherein when the output of said comparing means is within a predetermined range, a constant image density can be obtained by adjusting the toner layer thickness to the developing roller. Liquid developing electrophotographic device. 9. A liquid electrophotographic electrophotographic apparatus according to claim 7, wherein when the output of said comparison means falls within a certain range, a developing bias is adjusted to obtain a certain image density. . 10. A liquid developing electrophotographic apparatus using a non-volatile high-viscosity liquid toner in which toner particles are dispersed at a predetermined concentration in a liquid carrier as a liquid developing solution, wherein a bias voltage is applied to a toner supply roller. A developing roller to which liquid toner is supplied from the toner supply roller, a unit for measuring a bias current flowing through the toner supply roller, a unit for comparing the bias current with a predetermined set value, and the comparing unit When the output of (b) indicates a bias current smaller than the set value, the bias voltage applied to the toner supply roller is increased to increase the toner supply amount, and the output of the comparing means is set to the set value. When a larger bias current is shown, the bias voltage applied to the toner supply roller is lowered to reduce the toner supply amount. A liquid developing electrophotographic apparatus comprising: 11. The liquid developing electrophotographic apparatus according to claim 10, wherein a concave portion is provided in a mesh shape on a surface of said toner supply roller. 12. The liquid developing electrophotographic apparatus according to claim 11, wherein the convex surface of the toner supply roller having the mesh-shaped concave portion is made insulative.