KR20000057996A - Device and method for wet developing - Google Patents

Abstract

PURPOSE: A liquid developer device and a method thereof are provided to improve the developing capability of the developer device with a simplified structure. CONSTITUTION: A liquid developer device includes an electrostatic latent image forming device, a toner cluster emitter(22), and a carrier solvent reducer device. The electrostatic latent image forming device forms the electrostatic latent images on a latent image-bearing surface. The latent image formed on the latent bearing body is developed into a visual toner by using a liquid toner in which toner particles are dispersed. The toner cluster emitter(22) emits the induced toner cluster into the latent bearing body by using an electrostatic force based on the potential of the latent image. The carrier solvent reducer device reduces the carrier solvent on the visual toner so as to form a dot on the visual toner on the latent bearing body.

Description

DEVICE AND METHOD FOR WET DEVELOPING

The present invention relates to a liquid developing apparatus and method using a liquid toner (with toner particles dispersed in a carrier solvent), wherein the toner particles are subjected to electrostatic forces on a latent image formed on a latent image bearing body (latent image bearing belt, latent image bearing drum, etc.). Is released and thus the latent image is developed into a visible toner image.

A liquid developing method using a liquid developer for color copiers and printers in order to increase printing speed and print quality has recently been proposed.

In the liquid developing method disclosed in Japanese Patent Laid-Open No. Hei 8-015993, for example, a liquid developer made by dispersing toner particles in an insulating liquid is used. The toner particles of the developer are concentrated on the latent electrostatic image formed on the latent image bearing body due to electrophoresis, and thus image development is realized. Toner particles having a diameter of about 1 μm have a positive or negative charge in the liquid developer depending on the resin used for the toner particles or depending on the polarity control agent, so that the toner particles are dispersed and stabilized in the liquid developer. Suspended.

1 is a schematic diagram showing an example of a conventional liquid developing apparatus such as a copier, a printer, or the like using the conventional developing method described above. In Fig. 1, the conventional liquid developing apparatus includes a latent image bearing drum 28, a charging unit 2, an exposure unit 3, a developing unit 4, a squeeze roller 5, an image transfer roller 6 , Pressure roller 10, heating roller 11, cleaning blade 9, and neutralization lamp 8.

The charging unit 2 uniformly charges the surface of the latent image bearing drum 28. The exposure part 3 irradiates light, such as a laser beam, on the latent image bearing drum 28 to form an electrostatic latent image on the surface of the latent image bearing drum 28. The developing section 4 develops an electrostatic latent image, i.e., toner particles (liquid toner) in the liquid developer adhere to the electrostatic latent image on the latent image bearing drum 28, thereby causing the electrostatic latent image to become a visible toner image. The transfer roller 5 removes excess liquid developer from the latent image bearing drum 28 after the development by the developing portion 4. The image transfer roller 6 transfers the visible toner image on the latent image bearing drum 28 onto the media 7 such as paper. The pressure roller 10 and the heating roller 11 fix the visible toner image transferred onto the medium 7. The cleaning blade 9 removes the liquid developer remaining on the latent image bearing drum 28, and the neutralization lamp 8 removes the electrostatic charge remaining on the surface of the latent image bearing drum 28.

In the above-described conventional liquid developing apparatus, printing on the medium 7 such as paper is performed as follows.

First, a part of the surface of the latent image bearing drum 28 which is in contact with the charging unit 2 is uniformly charged by the charging unit 2, and thus the part is exposed by the rotation of the latent image bearing drum 28. 3) is delivered to. In the exposed portion 3, a portion of the surface of the latent image bearing drum 28 (hereinafter referred to as the colored portion) corresponding to the phase is irradiated to remove charges, so that an electrostatic latent image is placed on the surface of the latent image bearing drum 28. Is formed. A part of the latent image bearing drum 28 in which the latent electrostatic image is formed is transferred to the developing portion 4.

In the developing portion 4, the liquid developer containing toner particles 23 (charged with the same polarity as the electrostatic latent image on the latent image bearing drum 28) is developed by the developing roller 24. Is supplied to the surface of the toner particles 23, and thus the toner particles 23 adhere to the colored portions of the electrostatic latent image, whereby the electrostatic latent image is turned into a visible toner image. The remaining liquid developer on the latent image bearing drum 28 is removed by the transfer roller 5.

Thus, the medium 7 such as paper is pressed onto a part of the latent image bearing drum 28 in which the toner image is formed by the image transfer roller 6. The image transfer roller 6 is charged with the opposite polarity to the toner particles, whereby the toner image on the latent image bearing drum 28 is transferred to the surface of the medium 7. The toner image transferred to the medium 7 is then melted and fixed by the heating roller 11 and the pressure roller 10, whereby a permanent image is formed on the medium 7.

Thus, the residual liquid developer on the latent image bearing drum 28 is removed by the cleaning blade 9, and the electrostatic charges on the latent image bearing drum 28 are neutralized by irradiation with the neutralizing lamp 8. The above procedure, which is the charging by the charging unit 2 to the neutralizing furnace by the neutralizing lamp 8, is repeated so that continuous printing is performed on the medium 7.

In another liquid developing method disclosed in Japanese Patent Application Laid-open No. Hei 9-230704, for example, the phenomenon of electrostatic latent images formed on an image bearing body develops a drop of a liquid developer containing toner particles by a concentrated electric field. By electrostatic latent discharge from the electrode. The tip of the developing electrode opposing the electrostatic latent image is very sharply formed, so that the electric field generated between the latent electrostatic image and the developing electrode is concentrated on the tip of the developing electrode, and thus the liquid developer containing toner particles is the tip of the developing electrode. Attracted, forms a drop, and is thus rapidly transferred to the latent electrostatic image, so that the latent electrostatic image is developed into a visible toner image.

The first conventional liquid developing method (Japanese Patent Laid-Open No. 8-015993) has the following problems and disadvantages. First, in the first conventional liquid developing method, excess carrier solvent of the liquid developer is applied by the developing roller 24 together with the toner particles onto the latent image bearing drum 28, and thus transfer for removing excess carrier solvent. The transfer operation of the roller 5 becomes difficult.

Secondly, in a multicolor developing process using a series developing apparatus according to this conventional liquid developing method, the first carrier solvent (of the first liquid developer for the first color) attached to the latent image bearing drum 28 in the first development. The amount is large. Therefore, the toner particles of the first color tend to flow over the toner of the next color. When the toner image is formed on the latent image bearing drum 28, color mixing occurs because the carrier solvent of the liquid developer adheres to the colored portions and other portions of the surface of the latent image bearing drum 28 (hereinafter referred to as non-coloured portions). do.

Third, due to the excessive carrier solvent, carrier solvent evaporation occurs when fixing the toner phase on the medium 7 or the like, and therefore, a risk of releasing flammable gas may occur. In this case, there is a need for a flammable gas recovery system that prevents flammable gas leaks, thus increasing the cost for the liquid developing apparatus. This problem occurs because a large amount of carrier solvent is also attached onto the medium 7 together with the toner particles when the toner image generated on the latent image bearing drum 28 is transferred to the medium 7.

Fourthly, the liquid developing apparatus needs to have a complicated structure to realize the multicolor phenomenon. In the four cycle developing method for four colors, for example, the first color toner image is formed on the latent image bearing drum 28 and thus the second color toner image is formed. In the formation of the second color toner image using the second color liquid developer, toner particles on the first color toner formed on the latent image bearing drum 28 tend to drop into the second color developing region, whereby color mixing occurs. do. Color mixing also occurs on the latent image bearing drum 28 when the second color toner image is formed on top of the first color toner. In order to prevent color mixing, in general, each developed toner image on the latent image bearing drum 28 is transferred to another intermediate image bearing drum. The intermediate image transfer is repeated four times (for yellow, scarlet, cyan and black), and then the four color toner images on the intermediate phase bearing drum are transferred to the medium 7 and fixed. Therefore, the structure of the liquid developing apparatus needs to be complicated to realize the multicolor phenomenon.

Although the intermediate phase transfer is not used and the monochrome image transfer to the medium 7 is repeated four times, the liquid developing apparatus requires high precision position control to avoid toner image placement on the medium 7, and thus the liquid developing apparatus Requires a complicated structure. If four phase bearing drums 28 are provided for four colors, the structure of the liquid developing apparatus also needs to be complicated, so that a single color toner image can be formed on each phase bearing drum 28.

Fifth, in order to realize multicolor phenomenon or multicolor printing, the electrostatic latent image formation on the latent image bearing drum 28 must be repeated for multicolor. In a four cycle developing method using, for example, four colors, the image bearing drum 2 must be rotated four or more times. Therefore, if multicolor printing is required for the liquid developing apparatus, the printing speed inevitably slows down.

The second conventional liquid developing method (Japanese Patent Laid-Open No. 9-230704) can perform the latent electrostatic image development on the phase bearing body by releasing a drop of the liquid developer using an electric field concentrated from the developing electrode to the latent electrostatic image. . However, the conventional liquid developing method has not been applicable to multicolor development. For example, the above-mentioned patent publication does not mention any countermeasure against color mixing in a multicolor phenomenon. Therefore, the application of the conventional liquid developing method is limited to monochrome development.

It is a main object of the present invention to provide a liquid developing method and a liquid developing apparatus in which the developing performance can be improved as a liquid developing apparatus having a simple structure.

It is another object of the present invention to provide a liquid developing method and a liquid developing apparatus in which a high quality multicolor development is realized with a simple structure of a liquid developing apparatus.

According to a first aspect of the present invention, there is provided a liquid developing apparatus for developing an electrostatic latent image formed on a latent image bearing body using a liquid toner in which toner particles are dispersed, into a visible toner image. The liquid developing apparatus includes electrostatic latent image forming means, toner cluster ejecting means, and carrier solvent reducing means. The electrostatic latent image forming means forms an electrostatic latent image on the surface of the latent image bearing body. The toner cluster is a static latent image on the latent image bearing body using an electrostatic force that depends on the potential in the latent electrostatic image to form a cluster of charged liquid toners having a property of forming a film on the latent image bearing body when the carrier solvent is reduced to a certain level. Emit up and thus develop an electrostatic latent image into the visible toner image. The carrier solvent reducing means reduces the carrier solvent on the visible toner so that dots on the visible toner are formed into a film on the latent image bearing body.

According to a second aspect of the present invention, in the first aspect, the liquid developing apparatus further includes a latent image bearing body in which an electrostatic latent image is formed.

According to a third aspect of the invention, in a second aspect, the latent image bearing body is a latent image bearing belt.

According to a fourth aspect of the present invention, in the second aspect, the latent image bearing body is a latent image bearing drum.

According to a fifth aspect of the present invention, in the second aspect, the liquid developing apparatus further includes image transfer means for transferring the toner image just formed on the latent image bearing body to a medium such as paper.

According to a sixth aspect of the present invention, in the first aspect, the electrostatic latent image forming means includes charging means and exposure means. The charging means uniformly charges the surface of the latent image bearing body, and the exposure means irradiates light to form an electrostatic latent image on the surface of the latent image bearing body.

According to a seventh aspect of the present invention, in the sixth aspect, the exposure means forms an electrostatic latent image on the surface of the latent image bearing body by irradiating the colored portion of the surface of the latent image bearing body, thereby removing the charge in the colored portion. The toner cluster discharge means discharges the toner cluster charged with the same polarity as the charge on the surface of the latent image bearing body.

According to an eighth aspect of the present invention, in the sixth aspect, the exposure means forms an electrostatic latent image on the surface of the latent image bearing body by irradiating an uncolored portion of the surface of the latent image bearing body, thereby removing the charge in the non-colored portion. The toner cluster discharge means releases the toner cluster charged with the opposite polarity to the charge on the surface of the latent image bearing body.

According to a ninth aspect of the present invention, in the first aspect, the liquid developing apparatus is a multicolor liquid developing apparatus provided with at least two toner cluster ejecting means corresponding to each color.

According to a tenth aspect of the present invention, in the ninth aspect, a liquid developing apparatus such as a multicolor liquid developing apparatus is provided with four toner cluster ejecting means corresponding to yellow, magenta, cyan and black.

According to an eleventh aspect of the present invention, in the ninth aspect, the liquid developing apparatus is also provided with at least two charging means and at least two exposure means corresponding to each color. The charging means uniformly charges the surface of the latent image bearing body. The exposure means irradiates light to form an electrostatic latent image on the surface of the latent image bearing body.

According to a twelfth aspect of the present invention, in the first aspect, the toner cluster ejecting means is a recording head including a plurality of recording electrodes, a liquid toner chamber and a plurality of liquid toner channel grooves. Each recording electrode has a convex emission point. The developing bias voltage is applied to the write electrode. The liquid toner chamber stores liquid toner. The liquid toner channel grooves guide the liquid toner to the discharge point of the recording electrode.

According to a thirteenth aspect of the present invention, in the twelfth aspect, the recording electrodes of the recording heads are arranged at right angles to the moving direction of the latent image bearing body.

According to a fourteenth aspect of the present invention, in the twelfth aspect, the recording head performs a scan movement on the latent image bearing body. The recording electrodes of the recording heads are arranged at right angles to the moving direction of the latent image bearing body.

According to a fifteenth aspect of the present invention, in the twelfth aspect, the toner cluster uses an electrostatic force due to a potential difference between the potential on the electrostatic latent image and the developing bias voltage applied to the recording head, thereby causing the electrostatic latent image on the latent image bearing body from the recording head. It is emitted to the colored part of.

According to a sixteenth aspect of the present invention, in the twelfth aspect, the recording head further includes a plurality of electrophoretic electrodes provided in the liquid toner channel grooves. An electrophoretic voltage is applied to the electrophoretic electrode so that the toner particles of the liquid toner will be transferred to the emission point by electrophoresis.

According to a seventeenth aspect of the present invention, in a first aspect, the carrier solvent reducing means comprises a transfer roller. The transfer roller removes the carrier solvent from the visible toner image on the latent image bearing body by pressing the visible toner image, thereby forming dots on the visible toner into a film.

According to an eighteenth aspect of the invention, in a first aspect, the carrier solvent reducing means comprises a heater. The heater removes the carrier solvent from the visible toner image on the latent image bearing body by heating the visible toner image, thereby forming a dot on the visible toner into a film.

According to a nineteenth aspect of the present invention, in the first aspect, the carrier solvent reducing means comprises a fan. The fan removes the carrier solvent from the visible toner image on the latent image bearing body by panning the visible toner image, thereby forming a dot on the visible toner film.

According to a twentieth aspect of the invention, in a twelfth aspect, the carrier solvent reducing means comprises a developing bias voltage controller. The development bias voltage controller controls the development bias voltage applied to the recording electrode so that the concentration of the toner particles of the liquid toner around the discharge point is higher than the predetermined concentration, and accordingly, the percentage of the toner particles on the visible toner on the latent image bearing body is predetermined. It is higher than the percentage of.

According to a twenty-first aspect of the present invention, in a sixteenth aspect, the carrier solvent reducing means comprises an electrophoretic voltage controller. The electrophoretic voltage controller controls the electrophoretic voltage applied to the electrophoretic electrode so that the concentration of the particles of the liquid toner around the discharge point is higher than the predetermined concentration, so that the percentage of the toner particles on the visible toner on the latent image bearing body is predetermined. Make it higher than percent.

According to a twenty-second aspect of the present invention, there is provided a liquid developing method in which an electrostatic latent image formed on a latent image bearing body using a liquid toner in which toner particles are dispersed is developed into a visible toner image. The liquid developing method includes an electrostatic latent image forming step, a toner cluster ejecting step, and a carrier solvent reducing step. In the latent electrostatic image forming step, the latent electrostatic image is formed on the surface of the latent image bearing body. In the toner cluster discharge step, the toner cluster of charged toner particles having a property of forming a film on the latent image bearing body when the carrier solvent is reduced to a certain level is formed on the latent image bearing body using an electrostatic force depending on the potential of the electrostatic latent image. Is discharged over the latent electrostatic image, so that the latent electrostatic image is developed into a visible toner image. In the carrier solvent reduction step, the carrier solvent on the visible toner is reduced so that dots on the visible toner may be formed into a film on the latent image bearing body.

According to a twenty third aspect of the present invention, in the twenty second aspect, the liquid developing method further comprises a phase transfer step. In the image transfer step, the toner image just formed on the latent image bearing body is transferred onto a medium such as paper.

According to a twenty-fourth aspect of the present invention, in the twenty-second aspect, the electrostatic latent image forming step includes a charging step and an exposure step. In the charging step, the surface of the latent image bearing body is uniformly charged. In the exposing step, the electrostatic latent image is formed on the surface of the latent image bearing body by irradiating light.

According to a twenty-fifth aspect of the present invention, in the twenty-fourth aspect, the electrostatic latent image is formed on the surface of the latent image bearing body by irradiating the colored portion of the surface of the latent image bearing body in the exposing step, thereby removing the charge in the colored portion. In the toner cluster discharge step, the toner cluster charged with the same polarity as the charge on the surface of the latent image bearing body is released.

According to a twenty sixth aspect of the present invention, in the twenty-fourth aspect, the electrostatic latent image is formed on the surface of the latent image bearing body by irradiating the uncolored portion of the latent image bearing body in the exposing step, thereby removing the charge in the non-colored portion. In the toner cluster discharge step, the toner cluster charged with the polarity opposite to the charge on the surface of the latent image bearing body is released.

According to a twenty-seventh aspect of the present invention, in the twenty-second aspect, in the liquid developing method, the latent electrostatic image forming step, the toner cluster ejecting step, and the carrier solvent reducing step are performed N times (N: 2, 3, 4. .) Repeated multicolor liquid development method.

According to a twenty eighth aspect of the present invention, in the twenty-seventh aspect, the latent electrostatic image forming step, toner cluster ejecting step, and carrier solvent reducing step are repeated four times for yellow, magenta, cyan, and black.

According to a twenty-ninth aspect of the present invention, in the twenty-seventh aspect, the latent electrostatic image forming step, toner cluster ejecting step, and carrier solvent reducing step are repeated N times during one rotation of the latent image bearing body.

According to a thirtieth aspect of the present invention, in the twenty-second aspect, the toner cluster ejecting step is performed by a recording head including a plurality of recording electrodes, a liquid toner chamber and a plurality of toner channel grooves. Each recording electrode has a convex emission point. The developing bias voltage is applied to the write electrode. The liquid toner chamber stores liquid toner. Liquid toner channel grooves guide liquid toner to the discharge point of the recording head.

According to a thirty-first aspect of the present invention, in the thirtieth aspect, the toner cluster colorizes the electrostatic latent image of the latent image bearing body from the recording head using an electrostatic force due to a potential difference between the developing bias voltage applied to the recording electrode and the potential on the electrostatic latent image. Emitted over the site.

According to a thirty second aspect of the present invention, in the thirtieth aspect, the toner cluster discharging step further includes an electrophoretic voltage applying step. In the electrophoretic voltage application step, the electrophoretic voltage is applied to a plurality of electrophoretic electrodes provided in the liquid toner channel grooves of the recording head so that toner particles of the liquid toner are transferred to the discharge point by electrophoresis.

According to a thirty third aspect of the present invention, in the twenty-second aspect, the carrier solvent reducing means comprises a transfer step. In the transfer step, the transfer roller is pressed against the visible toner image on the latent image bearing body to remove the carrier solvent from the visible toner image, whereby dots on the visible toner are formed into a film.

According to a thirty-fourth aspect of the present invention, in the twenty-second aspect, the carrier solvent reducing step comprises a heating step. In the heating step, the visible toner phase on the latent image bearing body is heated to remove the carrier solvent from the visible toner phase, whereby dots on the visible toner are formed into a film.

According to a thirty fifth aspect of the present invention, in the twenty second aspect, the carrier solvent reducing step comprises a panning step. In the panning step, the visible toner image on the latent image bearing body is panned to remove the carrier solvent from the visible toner image, whereby dots on the visible toner are formed into a film.

According to a thirty sixth aspect of the present invention, in the thirtieth aspect, the carrier solvent reducing step comprises a developing bias voltage controlling step. In the development bias voltage control step, the development bias voltage applied to the recording electrode is controlled so that the concentration of the toner particles of the liquid toner around the discharge point is higher than the predetermined concentration, and thus the percentage of the toner particles on the visible toner on the latent image bearing body is increased. It is higher than a predetermined percentage.

According to a thirty seventh aspect of the invention, in the thirty second aspect, the carrier solvent reducing step comprises an electrophoretic voltage control step. In the electrophoretic voltage control step, the electrophoretic voltage applied to the electrophoretic electrode is controlled so that the concentration of the toner particles of the liquid toner around the discharge point is higher than a predetermined concentration, and thus the percentage of the toner particles on the visible toner on the latent image bearing body. Is higher than the predetermined percentage.

1 is a schematic diagram showing an example of a conventional liquid developing apparatus.

2 is a schematic view showing a liquid developing apparatus according to a first embodiment of the present invention.

3 is a perspective view of the recording head of the liquid developing apparatus of FIG. 2;

4 is an enlarged perspective view of a portion A of the recording head of FIG.

FIG. 5A is an enlarged plan view of the recording head of FIGS. 3 and 4 seen in the B direction shown in FIG.

FIG. 5B is an enlarged cross sectional view of the recording head of FIGS. 3 and 4 seen in the C direction shown in FIG.

6 is an enlarged cross sectional view showing a front portion of a recording head;

FIG. 7A is a graph for explaining that a developing bias voltage Veb is applied to a recording electrode of a recording head. FIG.

FIG. 7B is a schematic diagram showing a potential distribution on a latent bearing belt of the liquid developing apparatus of FIG. 2; FIG.

FIG. 7C is a schematic diagram showing the removal of charge on the latent image bearing belt due to light radiation by the exposed portion of the liquid developing apparatus of FIG. 2; FIG.

FIG. 7D is a schematic diagram showing light emission onto a latent image bearing belt; FIG.

Fig. 8 is a schematic diagram showing the principle of discharge of the recording head of the liquid developing apparatus of the present invention in which the relationship between the recording electrode and the counting electrode is shown.

9A is a graph showing the electrophoretic voltage Vep applied to the electrophoretic electrode of the recording head.

Fig. 9B is a graph showing the developing bias voltage Veb applied to the recording electrode of the recording head.

9C is a graph showing the voltage change at the counting electrode.

Fig. 10 is a schematic diagram showing a state of meniscus formed near the discharge point of the recording head.

11 is a schematic view showing a liquid developing apparatus according to a second embodiment of the present invention.

12 is a schematic view showing a liquid developing apparatus according to a third embodiment of the present invention.

Explanation of Signs of Major Parts of Drawings

1 latent bearing belt 2

3 exposed part 4 developed part

5 transfer roller and 6 phase transfer roller

7 medium 8 neutralizing lamp

9 Cleaning blade 10 Pressing roller

11 heating roller 13 recording head

14 Liquid Toner Chamber 15 Ejection Opening

16 Electrophoresis Electrode 17 Recording Electrode

18 Liquid Toner Supply Hole 19 Liquid Toner Outlet Hole

20 channel wall 21 liquid toner

22 Toner Cluster 23 Toner Particles

24 Developing roller 30 ejection point

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A detailed description of a preferred embodiment according to the present invention is given with the drawings.

2 is a schematic diagram showing a liquid developing apparatus according to a first embodiment of the present invention. In FIG. 2, the liquid developing apparatus of the first embodiment includes a latent image bearing belt 1, developing portions 4a-4d, an image transfer roller 6, a heating roller 11, and a neutralizing lamp 8.

The developing portions 4a-4d corresponding to four colors (yellow, scarlet, cyan, black) are provided in the liquid developing apparatus of FIG. 2 in a series configuration. Each developing portion 4a-4d is provided with a charging portion 2, an exposure portion 3, a transfer roller 5 and a recording head 13.

Further, the charging portion 2 of the developing portion 4a with respect to yellow is disposed outside the developing portion 4a (that is, in front of the developing portion 4a), and the angles of the developing portions 4b-4d with respect to the other colors are different. The charging section 2 is disposed in each developing section 4b-4d. The charging section 2 of each developing section 4a-4d uniformly charges the surface of the latent image bearing belt 1.

The exposure part 3 irradiates the latent image bearing belt 1 with light, such as a laser beam, to form an electrostatic latent image on the surface of the latent image bearing belt 1. The recording head 13 discharges the toner cluster onto the electrostatic latent image of the surface of the latent image bearing belt 1, thereby developing the electrostatic latent image into the visible toner image. The transfer roller 5 removes excess carrier solvent from the toner image on the latent image bearing belt 1 after development, whereby toner particles (liquid developer, ink) of the liquid toner on the latent image bearing belt 1 are transferred to the film. Is formed.

A film (or film island) of toner particles is formed on the surface of the latent image bearing belt 1 corresponding to each dot of the toner cluster in contact with the latent image bearing belt 1. Due to the reduction of the carrier solvent, the toner particles of the dot are agglomerated and thus a toner particle film (ie, film islands) is formed quickly.

Suitable materials for liquid toners formed into films are described in detail in US Pat. No. 5,650,253 (columns 10, 8 to 13, 14) and US Pat. No. 5,698,616.

From the recording head 13, the toner cluster 22 (containing mobile toner particles (charged to the same polarity as the electrostatic latent image formed on the surface of the latent image bearing belt 1)) is ejected onto the latent image bearing belt 1 .

The image transfer roller 6 transfers the visible toner image formed on the latent image bearing belt 1 onto a medium such as paper. Further, the image transfer roller 6 is provided between the latent image bearing belt 1 and the medium 7 so that the surface of the latent image bearing belt 1 is not contaminated with dust (paper dust or the like) from the medium 7. The heating roller 11 fixes the visible toner image transferred onto the medium 7. The neutralization lamp 8 neutralizes the residual charge (corresponding to the electrostatic latent image) on the surface of the latent image bearing belt 1.

In addition, the cleaning blade 9 used in the conventional liquid developing apparatus of FIG. 1 is unnecessary in the liquid developing apparatus of FIG. In the experiments performed by the present inventors, in the liquid developing apparatus according to the present invention, the toner image formed on the latent image bearing belt 1 has a surface energy between the latent image bearing belt 1, the image transfer roller 6, and the medium 7. (ε) (thus, surface tension γ) is transmitted to the image transfer roller 6 and the medium 7 by controlling the relationship. However, the cleaning blade 9 may be provided to the latent image bearing belt 1 and the image transfer roller 6 in order to prepare for problems such as printing interference due to paper jam. The following description assumes that the cleaning blade 9 is not installed in the liquid developing apparatus of FIG.

FIG. 3 is a perspective view of the recording head 13 of the liquid developing apparatus of this embodiment, and FIG. 4 is an enlarged perspective view of part A of the recording head of FIG. The recording head 13 includes a liquid toner chamber 14, an electrophoretic electrode 16, a recording electrode 17, a liquid toner channel groove 29, and a channel wall 20.

The liquid toner chamber 14 stores liquid toner supplied from a liquid toner tank (not shown). The liquid toner chamber 14 has a liquid toner supply hole 18 and a liquid toner outlet hole 19 and is connected to a liquid toner tank (not shown) through a tube (not shown). The liquid toner chamber 14 again applies pressure to the liquid toner and forcibly circulates or agitates the liquid toner. The electrophoretic electrode 16 applies an electric field to the toner particles of the liquid toner and thus transfers the toner particles to the tip of the recording head 13 by electrophoresis. In the recording head 13, the plurality of recording electrodes 17 are, for example, latent image bearing belts (when the width of the recording head 13 is approximately equal to the width of the latent image bearing belt 1 or the medium 7). It is arranged perpendicular to the moving direction of (1). It is also possible for the recording head 13 to perform a scan movement (forward and backward direction) under the latent image bearing belt 1. In this case, the recording electrodes 17 of the recording head 13 are arranged in parallel with the moving direction of the latent image bearing belt 1. The end portion of the recording electrode 17 forms a convex discharge point 30 from which toner particles transferred by the electrophoretic electrode 16 are released. Liquid toner channel grooves 29 direct liquid toner to discharge point 30. The channel wall 20 is formed to distinguish the liquid toner channel grooves 29.

FIG. 5A is an enlarged plan view of the recording head 13 of FIGS. 3 and 4 seen in the B direction shown in FIG. 5A shows the relationship between the discharge point of the recording head 13 and the latent image bearing belt 1. FIG. 5B is an enlarged front view of the recording head 13 of FIGS. 3 and 4 seen in the C direction shown in FIG. As shown in FIG. 5A, the discharge opening 15 is formed between the recording electrodes 17 of the recording head 13. A meniscus 27 of liquid toner is formed between the discharge points 30 of the recording electrodes 17. A description of the meniscus 27 formation is given later. A plurality of liquid toner channel grooves 29 are formed between the recording electrodes 17 separated by the channel walls 20. From the convex discharge point 30, the toner cluster 22 is discharged onto the latent image bearing belt 1.

6 is an enlarged cross-sectional view showing the front of the recording head 13. As shown in FIG. 6, the liquid toner 21 supplied from the liquid toner supply hole 18 shown in FIG. 3 flows along the liquid toner channel groove 29 to the discharge point 30. At the bottom of the liquid toner channel groove 29 formed on the substrate 31, the electrophoretic electrode 16 is patterned to keep in contact with the liquid toner 21.

The electrophoretic voltage Vep is applied to each electrophoretic electrode 16. The recording electrode 17 patterned to reach the discharge point 30 is provided with an insulating coating 32, so that the surface of the recording electrode 17 is applied by the insulating coating 32. The developing bias voltage Veb is applied to each electrophoretic electrode 16. Due to the application of the electrophoretic voltage Vep, the toner particles 23 of the liquid toner 21 are moved to the free surface of the liquid toner 21 and concentrated at the discharge point 30.

FIG. 7A is a graph for explaining the developing bias voltage Veb applied to the recording electrode 17. FIG. In FIG. 7A, a constant developing bias voltage Veb is applied to the write electrode 17.

7B is a graph showing the potential distribution on the latent image bearing belt 1. 7C and 7D are schematic diagrams showing the state of charge of the surface of the latent image bearing belt 1. First, the surface of the latent image bearing belt 1 is uniformly charged by the charging unit 2 and has a surface voltage Vo (about 600 to 650 V) as shown in FIG. 7D. When the colored portion of the latent image bearing belt 1 (that is, the portion of the latent image bearing belt 1 to be colored by the toner particles 23) is irradiated by the exposure portion 3, the irradiated portion (that is, colored) Part) is removed as shown in FIG. 7C, whereby the surface potential at the colored portion of the latent image bearing belt 1 is reduced to Vi (50 to 100 V), while the other side of the latent image bearing belt 1 is reduced. The surface potential at the portion becomes Voi (about 550 to 600V) as shown in FIG. 7B.

The ejection principle of the recording head 13 is explained in conjunction with Figs. 8 to 9C.

First, the voltage application of the counting electrode 26 and the recording electrode 17 necessary for toner particle ejection is described. In addition, in the actual liquid developing apparatus, the counting electrode 26 is not provided, and the voltage (potential) on the surface of the latent image bearing belt 1 due to the electric charge corresponds to the voltage applied to the counting electrode 26. 8 is a schematic diagram illustrating a relationship between the recording electrode 17 and the counting electrode 26. In order to discharge the toner particles 23 from the recording electrode 17, a constant voltage difference (potential difference) between the recording electrode 17 and the counting electrode 26 is required. The minimum voltage difference between the recording electrode 17 and the counting electrode 26 through which toner particles can be emitted is referred to as threshold voltage Vth. The toner particles 23 are emitted from the recording electrode 17 when the voltage difference is more than Vth, and the toner particles 23 are not emitted from the recording electrode 17 when the voltage difference is less than Vth.

9A to 9C are graphs showing voltages applied to the electrophoretic electrode 16, the recording electrode 17, and the counting electrode 26. Figs. As shown in FIG. 9A, an electrophoretic voltage Vep is applied to the electrophoretic electrode 16 to transfer the toner particles 23 to the emission point 30 by electrophoresis. The voltage difference Veb-Vd1 between the recording electrode 17 and the counting electrode 26 is equal to or greater than the threshold voltage Vth as shown in Figs. 9B and 9C, and the toner particles 23 are separated from the recording electrode 17. Electrostatic force that can be moved to the tip and released from the discharge point 30 is applied to the toner particles 23. Due to the electrostatic force (i.e. surface tension, viscosity of liquid toner, etc.) larger than the meniscus force, the toner particles 23 escape from the meniscus 27 (formed by the fine toner cluster 22) and the recording electrode ( Is emitted from the release point 30 of 17). Toner particles corresponding to the amount of the toner cluster 22 released are supplied to the discharge point 30 through the liquid toner supply hole 18, the liquid toner chamber 14, and the liquid toner channel groove 29 by electrophoresis. . By repeating this operation, the toner particles 23 from the recording electrode 17 are discharged continuously (repeated).

When the voltage difference (Veb-Vd) between the recording electrode 17 and the counting electrode 26 is smaller than the threshold voltage Vth, the necessary electrostatic force is not applied to the toner particles 23 so that the toner particles 23 do not have the recording electrode. It is released from (17).

FIG. 10 is a schematic diagram showing a meniscus 27 state formed near the discharge point 30. The toner particles 23 in the liquid toner chamber 14 move along the discharge point 30 by the electrostatic force due to the electrophoretic voltage Vep and the developing bias voltage Veb, and thus preparation for discharge is completed. At this time, the voltage difference lower than the threshold voltage Vth, i.e., the discharge of the toner cluster 22 does not occur and the meniscus of the liquid toner 21 is formed in the discharge opening 15 between the recording electrodes 17.

Next, the operation of the liquid developing apparatus of FIG. 2 will be described in detail.

First, the surface of the latent image bearing belt 1 is uniformly charged by the charging portion 2 of the developing portion 4a with respect to yellow color. Subsequently, the above-described colored portion (for yellow) of the latent image bearing belt 1 is irradiated by the exposed portion 3 of the developing portion 4a so that the charges at the colored portion are removed, whereby the charge on the colored portion is A negative electrostatic latent image for the removed yellow color is formed on the latent image bearing belt 1.

The image is irradiated by the exposure portion 3, so that the potential on the latent image bearing belt 1 becomes as shown in Fig. 7B. At this time, the electrophoretic voltage Vep is applied to the electrophoretic electrode 16 of the recording head 13 for yellow color and thus yellow toner particles 23 are transferred to the emission opening 15 of the recording head 13. do.

At the same time, the developing bias voltage Veb (about 1000 V) is applied to the write electrode 17, and thus a meniscus 27 is formed between the tips of the write electrode 17 as shown in FIG. When the coloring portion Vi on the latent image bearing belt 1 (Vi: about 50 to 100V) is transferred to the recording head 13 for yellow color and directed toward the recording head 13, the voltage difference between the recording electrode 17 and the coloring portion (Veb-Vi) is equal to or higher than the threshold voltage Vth (for example, 600 to 800 V), and yellow toner cluster 22 is thus discharged from the discharge point 30 to the colored portion of the latent image bearing belt 1. The yellow toner cluster 22 is moved to and attached to the colored portion, whereby a yellow toner image is generated on the latent image bearing belt 1.

On the other hand, the potential Voi of the non-colored portion described in Figs. 7B and 7C is about 500 to 600 V, so that the voltage difference (Veb-Voi) between the recording electrode 17 and the non-colored portion (for yellow) is critical. Less than the voltage (Vth; 600 ~ 800V). Thus, the toner cluster 22 is not discharged above the non-colored portion of the latent image bearing belt 1.

After the yellow toner image is formed on the latent image bearing belt 1, the transfer roller 5 of the developing portion 4a pressurizes the yellow toner phase, thereby removing the excess carrier solvent on the yellow toner phase. By removing the carrier solvent, each dot on the yellow toner (corresponding to the yellow toner cluster 22) is formed into a film (membrane island, film fragment, etc.), and thus the yellow toner image is formed into a film on the latent image bearing belt 1. do.

According to the experiment conducted by the inventor, when the percentage of the toner particles (amount) 23 on the first color toner is increased by being increased by a certain percentage (for example, 53%) by the transfer roller 5, The first color toner image on the latent image bearing belt 1 does not adversely affect the following color toner. In addition, the inventors have found that if the toner particle percentage of the toner image (or toner cluster 22 in contact with the surface of the latent image bearing belt 1) is higher than a certain percentage (for example, 53%) by experiment (the adverse effect is not affected). It has been found that the transfer operation of the transfer roller 5 can be omitted).

Thereafter, the surface of the latent image bearing belt 1 is uniformly charged by the charging portion 2 of the developing portion 4b against magenta. Thereafter, the colored portion of the latent image bearing belt 1 (for magenta) is irradiated by the exposed portion 3 of the developing portion 4b to remove the charge on the colored portion, thereby removing the charge on the colored portion. A negative electrostatic latent image is formed on the latent image bearing belt 1. The image is irradiated by the exposure portion 3, so that the potential on the latent image bearing belt 1 becomes as shown in Fig. 7B.

At this time, the electrophoretic voltage Vep is applied to the electrophoretic electrode 16 of the recording head 13 for magenta and thus the magenta toner particles 23 are transferred to the emission opening 15 of the recording head 13. do. At the same time, the developing bias voltage Veb is applied to the recording electrode 17, whereby the meniscus 27 of the magenta liquid toner is formed between the tips of the recording electrode 17 as shown in FIG. When the coloring portion Vi on the latent image bearing belt 1 (Vi: about 50 to 100V) is transferred to the recording head 13 for yellow color and directed toward the recording head 13, the voltage difference between the recording electrode 17 and the coloring portion (Veb-Vi) is equal to or higher than the threshold voltage Vth, and thus the magenta toner cluster 22 is discharged from the discharge point 30 to the colored portion of the latent image bearing belt 1. The magenta toner cluster 22 is moved to and attached to the colored portion, whereby a magenta toner image is produced on the latent image bearing belt 1.

On the other hand, the voltage difference (Veb-Voi) between the recording electrode 17 and the uncolored portion (for magenta) is less than the threshold voltage Vth. Thus, the toner cluster is not discharged onto the non-colored portion of the latent image bearing belt 1.

After the magenta toner image is formed on the latent image bearing belt 1, the transfer roller 5 of the developing portion 4b pressurizes the magenta toner phase, thereby removing excess carrier solvent on the magenta toner phase. By removing the carrier solvent, each dot on the magenta toner (corresponding to the magenta toner cluster 22) is formed into a film (membrane island, film fragment, etc.), and thus the magenta toner image is formed into a film on the latent image bearing belt 1. do. When the transfer operation of the transfer roller 5 to magenta is performed, the yellow toner image is already formed as a film on the latent image bearing belt 1, so that the yellow toner particles 23 are latent image bearing belts due to the transfer operation to magenta. It does not fall from (1).

Toner images of each color (yellow, magenta, cyan, black) are formed as a film on the latent image bearing belt 1 in each of the developing portions 4a-4d, so that the particles of the colored toner image develop in different colors in subsequent steps. Does not go into wealth Thus, color mixing is prevented. By the above steps, the film-forming magenta toner image is formed on the latent image bearing belt 1 after the film on the yellow toner is formed.

Thereafter, the same steps are repeated with the respective developing portions 4c and 4d for cyan and black, so that the film forming toner images for yellow, magenta, cyan and black are formed on the latent image bearing belt 1.

Then, the film-forming toner image on the latent image bearing belt 1 is transferred to the image transfer roller 6 and then to the medium 7. At the same time, heat and pressure are applied by the heating roller 11 and the image transfer roller 6 to the medium 7 to which the film-forming toner image has been transferred, whereby the toner phase is melted and fixed onto the medium 7 as a permanent phase. .

Therefore, the residual charge on the latent image bearing belt 1 is irradiated and neutralized by the neutralization lamp 8. From the charging by the charging section 2 of the developing section 4a to the neutralizing furnace sequence by the neutralizing lamp 8 is repeated, thereby performing continuous multicolor printing.

As described above, in the liquid developing apparatus according to the first embodiment of the present invention, the toner cluster 22 is a latent image from the recording electrode 17 of the recording head 13 by an electrostatic force depending on the potential in the electrostatic latent image. The latent electrostatic latent image of the bearing belt 1 is discharged, whereby the toner cluster 22 is selectively discharged only above the colored portion. Therefore, the amount of carrier solvent attached to the latent image bearing belt 1 is greatly reduced, so that the transfer operation of the transfer roller 5 to remove excess carrier solvent on the latent image bearing belt 1 can be performed easily and accurately. have.

By selective toner cluster release, the amount of carrier solvent attached onto the latent image bearing belt 1 in the first color development is greatly reduced. Thus, the flow of the first color toner particles 23 onto the toner image of the second color can be prevented and thus color mixing between the first color toner image and the second color toner image can be prevented.

As described above, the transfer operation of the transfer roller 5 in the tandem color liquid developing apparatus of the first embodiment can also be omitted by increasing the percentage of toner particles 23 on the toner on the latent image bearing belt 1. . Several methods can be used to increase the percentage of toner particles 23 on the toner. That is, a method of increasing the electrophoretic voltage Vep of the electrophoretic electrode 16 and thus increasing the toner particles 23 concentrated at the discharge point 30, increasing the developing bias voltage Veb of the recording electrode 17. A method of increasing the percentage of toner particles 23 of the liquid toner, and the like.

By reducing the amount of carrier solvent adhered to the latent image bearing belt 1, the amount of carrier solvent transferred from the latent image bearing belt 1 to the medium 7 during the image transfer is greatly reduced, thus reducing the toner image in the medium 7. The risk of flammable gas generation during fixation can be avoided. Therefore, the liquid developing apparatus does not need to be equipped with a flammable gas recovery system to prevent flammable gas leakage, and thus an increase in cost can be avoided.

The toner images of each color in the latent image bearing belt 1 are formed into a film by the transfer operation of the transfer roller 5 for each color, and thus the previous image from the latent image bearing belt 1 in the subsequent transfer operation for the color. The fall off of the color toner particles 23 does not occur. Thus, the multicolor phenomenon is accurately realized without the complexity of the liquid developing apparatus.

The multicolor phenomenon in the latent image bearing belt 1 is caused by the electrostatic latent image formation for each color in the latent image bearing belt 1 and the selective release of the toner cluster 22 (of the toner particles 23) of each color. It is carried out continuously by the parts 4a-4d. The multicolor phenomenon can be carried out every cycle of the latent image bearing belt 1, and therefore, a high speed multicolor phenomenon can be realized.

Due to the film formation on each toner phase in the latent image bearing belt 1, the separation of the toner particles 23 on one color toner from the latent image bearing belt 1 to the developing part of another color does not occur in a later step. Thus, color mixing at the developing portion can also be prevented. The intermediate phase transfer described above using an extra intermediate phase bearing drum or the like is unnecessary, and thus the structure of the multicolor liquid developing apparatus can be simplified.

Further, while the above description is given on the assumption that a negative electrostatic latent image (with the charge in the colored portion removed) is formed on the latent image bearing belt 1, a positive electrostatic latent image may also be used. This is made possible by charging the toner cluster 22 (emitted from the recording head 13) which is the polarity opposite to that of the electrostatic latent image in the latent image bearing belt 1.

While the latent image bearing belt 1 is used as the latent image bearing body which exhibits an electrostatic latent image in the above description, other types of latent image bearing bodies such as a latent image bearing drum may be used.

In the above description, the transfer roller 5 is used to remove the carrier solvent from the toner phase and thus the toner cluster 22 discharged is formed into a film on the latent image bearing belt 1, while other mechanisms for film formation are also Can be used. For example, heaters and / or fans provided near the latent image bearing belt 1 may also be used for carrier solvent removal and film formation. In addition, as described above, if the toner particle percentage of the toner cluster 22 in contact with the latent image bearing belt 1 is higher than a certain percentage (for example, 53%), the toner image is momentarily (toner of the following color). In the phase) which does not adversely affect the phase. As described above, the electrophoretic voltage Vep of the electrophoretic electrode 16 is raised and accordingly the toner particles 23 concentrated at the discharge point 30 are increased, and the developing bias voltage Veb of the recording electrode 17 is increased. High toner particles can be obtained by increasing the toner particles 23 percent of the liquid toner.

11 is a schematic diagram showing a liquid developing apparatus according to a second embodiment of the present invention. In Fig. 11, the liquid developing apparatus of the second embodiment includes a latent image bearing belt 1, a charging portion 2, a monochrome developing portion 4e, an image transfer roller 6, a heating roller 11, and a neutralization lamp 8 )

The monochromatic developing portion 4e includes an exposure portion 3, a transfer roller 5, and a recording head 13. As described above, the recording head 13 discharges the toner cluster 22 (charged with the same polarity as the electrostatic latent image formed on the surface of the latent image bearing belt 1) onto the latent image bearing belt 1.

In the following, the operation of the liquid developing apparatus of FIG. 11 is described in detail.

First, the surface of the latent image bearing belt 1 is uniformly charged by the charging unit 2. Subsequently, the colored portion of the latent image bearing belt 1 is irradiated by the exposed portion 3 of the monochrome developing portion 4e to remove the charges on the colored portion, whereby a negative electrostatic latent image (in which the charge on the colored portion is removed) is removed. The latent image bearing belt 1 is formed.

The image is irradiated by the exposure portion 3, so that the potential of the latent image bearing belt 1 becomes as shown in Fig. 7B. At this time, the electrophoretic voltage Vep is applied to the electrophoretic electrode of the recording head 13 of the monochromatic developing portion 4e (see FIGS. 4 and 6) and thus the toner particles 23 are separated from the recording head 13. To the discharge opening 15 (see FIG. 10).

At the same time, the developing bias voltage Veb (about 1000 V) is applied to the write electrode 17, and thus a meniscus 27 is formed between the tips of the write electrode 17 as shown in FIG.

When the colored portion Vi on the latent image bearing belt 1 (Vi: about 50 to 100V) is transferred to the recording head 13 to face the recording head 13, the voltage difference Veb between the recording electrode 17 and the colored portion Vi) is greater than or equal to the threshold voltage Vth (for example, 600 to 800 V), and accordingly, according to the emission principle described in FIGS. 8 to 9C, the toner cluster 22 has a latent image bearing belt ( It is emitted to the colored part of 1). The monochrome toner cluster 22 is moved to the colored portion and fixed, whereby a monochrome toner image is produced on the latent image bearing belt 1.

On the other hand, the potential Voi of the non-colored portion is about 500 to 600 V, and therefore the voltage difference Veb-Voi between the recording electrode 17 and the non-colored portion is smaller than the threshold voltage Vth (600 to 800 V). Thus, the monochrome toner cluster 22 is not discharged onto the non-colored portion of the latent image bearing belt 1.

After the monochromatic toner image is formed on the latent image bearing belt 1, the transfer roller 5 of the monochromatic developing portion 4e pressurizes the monochromatic toner image and thus excess carrier solvent of the monochromatic toner phase is removed. By removing the carrier solvent, each dot on the monochrome toner (corresponding to the monochrome toner cluster 22) is formed into a film (membrane island, film fragment, etc.), whereby the monochrome toner image is transferred to the film on the latent image bearing belt 1. Is formed.

Then, the film-forming monochromatic toner image on the latent image bearing belt 1 is transferred to the image transfer roller 6 and then to the medium 7. At the same time, heat and pressure are applied by the heating roller 11 and the image transfer roller 6 to the medium 7 on which the film-forming monochrome toner image is transferred, whereby the monochrome toner image is melted onto the medium 7 as a permanent phase. It is fixed.

Thereafter, the remaining charge on the latent image bearing belt 1 is irradiated with a neutralizing lamp 8 to be neutralized. This sequence, from charging by the charging unit 2 to neutralization furnace by the neutralizing lamp 8, is repeated and subsequent monochromatic printing is performed.

As described above, in the monochromatic liquid developing apparatus according to the second embodiment of the present invention, the toner cluster 22 is selectively discharged only in the colored portion, so that the amount of carrier solvent attached on the latent image bearing belt 1 is greatly reduced. And the transfer operation of the transfer roller 5 for removing excess carrier solvent on the latent image bearing belt 1 can be easily and accurately performed.

Similarly to the first embodiment, by reducing the amount of carrier solvent attached onto the latent image bearing belt 1, the amount of carrier solvent in the phase transfer from the latent image bearing belt 1 to the medium 7 is greatly reduced, and thus the attachment The generation of flammable gases at the time can be avoided. A flammable gas recovery system is unnecessary and thus the liquid developer apparatus cost can be reduced.

Further, in the above description, the exposure part 3 may be disposed inside the monochrome developing part 4e, while it may be disposed outside the monochrome exposure part 4e (forward).

12 is a schematic diagram showing a liquid developing apparatus according to a third embodiment of the present invention. In Fig. 12, the liquid developing apparatus of the third embodiment includes a latent image bearing belt 1, a charging portion 2, an exposure portion 3, a developing portion 4f to 4i, an image transfer roller 6, a heating roller ( 11), the neutralization lamp 8, and the expansion mechanism 33.

In the liquid developing apparatus of FIG. 12, each of the liquid developing portions 4f to 4i is not provided with a unique exposure portion 3 unlike the first embodiment shown in FIG. 2. Thus, only one charging portion 2 and one exposure portion 3 are provided in the liquid developing apparatus of FIG. 12.

The developing portions 4f to 4i are provided in the liquid developing apparatus of Fig. 12 in a series configuration corresponding to four colors (yellow, magenta, cyan, black). Each developing portion 4f to 4i includes a transfer roller 5 and a recording head 13. The stretching mechanism 33 moves the image transfer roller 6 vertically between the latent image bearing belt 1 and the medium 7.

In the following, the operation of the liquid developing apparatus of FIG. 12 is described in detail.

First, the expansion and contraction mechanism 33 sets the image transfer roller 6 at an upper position so as not to come into contact with the latent image bearing belt 1. In the first rotation of the latent image bearing belt 1, the surface of the latent image bearing belt 1 is uniformly charged by the charging portion 2 and the colored portion (for yellow) of the latent image bearing belt 1 is exposed to the exposure portion 3. ) To remove the charge on the colored portion, whereby a negative electrostatic latent image for the yellow color (with the removed portion of the colored portion removed) is formed on the latent image bearing belt (1). Thus, the film-forming yellow toner image is formed on the latent image bearing belt 1 by the developing portion 4f in the same manner as in the first embodiment.

In the second rotation of the latent image bearing belt 1, the surface of the latent image bearing belt 1 is uniformly charged by the charging portion 2 and the colored portion (for magenta) of the latent image bearing belt 1 is exposed to the exposure portion 3. ), And the charge on the colored portion is removed so that a negative electrostatic latent image for magenta is formed on the latent image bearing belt 1. Then, the film-forming magenta toner image is formed on the latent image bearing belt 1 by the developing portion 4g in the same manner as the developing process for yellow.

The same process is then repeated for cyan and black, whereby the film forming cyan toner image is formed in the third rotation of the latent image bearing belt 1 and the film forming black toner image is formed in the fourth rotation of the latent image bearing belt 1. . In the above process, the film forming toner image for yellow, magenta, cyan and black is formed on the latent image bearing belt 1.

Thereafter, the image transfer roller 6 is lowered by the expansion mechanism 33 to come into contact with the latent image bearing belt 1, whereby the film-forming toner image on the latent image bearing belt 1 is transferred to the image transfer roller 6. do.

Thereafter, the image transfer roller 6 is raised by the stretching mechanism 33 to come into contact with the medium 7, whereby the film-forming toner image on the image transfer roller 6 is transferred to the medium 7. At the same time, heat and pressure are applied by the heating roller 11 and the image transfer roller 6 to the medium 7 on which the film-forming toner image is transferred, whereby the toner image is melted and fixed onto the medium 7 as a permanent phase. .

Thereafter, the remaining charge on the latent image bearing belt 1 is irradiated by the neutralizing lamp 8 to be neutralized. This sequence, from charging by the charging unit 2 to neutralization furnace by the neutralizing lamp 8, is repeated so that continuous multicolor printing is performed.

As described above, in the liquid developing apparatus according to the third embodiment of the present invention, a film-forming toner image of each color is formed on the latent image bearing belt 1 for each rotation of the latent image bearing belt 1. The electrostatic latent image for four colors is produced by only one pair of the charging section 2 and the exposure section 3. Therefore, the configuration of the liquid developing apparatus can be simplified as compared with the first embodiment, and thus the cost can be reduced.

Further, in the above description, while each of the developing portions 4f to 4i is provided with a transfer roller 5 unique to each color, it is also possible to use only one transfer roller 5 in common to the developing portions 4f to 4i. It is possible.

As described above, in the liquid developing method and liquid developing apparatus according to the present invention, the electrostatic latent image formed on the latent image bearing body (such as the latent image bearing belt 1) is developed into a visible toner image by using a liquid toner in which toner particles are dispersed. The charged toner cluster of liquid toner having a property of forming a film on the latent image bearing body when the carrier solvent is reduced to a certain level is discharged onto the latent electrostatic image on the latent image bearing body by an electrostatic force depending on the potential in the latent electrostatic image. Being. The electrostatic latent image is thus developed into a visible toner image. The carrier solvent on the visible toner is reduced by a transfer roller or the like so that dots on the visible toner can be formed into a film on the latent image bearing body.

Therefore, the amount of carrier solvent attached to the latent image bearing body is greatly reduced, and accordingly, the transfer operation for removing excess carrier solvent on the latent image bearing body can be performed easily and accurately. By reducing the amount of carrier solvent on the latent image bearing body, flammable gas generation can be prevented and no additional cost for the flammable gas recovery system is required. By reducing the carrier solvent on the latent image bearing body and forming a toner phase film on the latent image bearing body, color mixing is realized with a simple configuration of the liquid developing apparatus. The multicolor phenomenon can be performed with only one cycle (rotation) of the latent image bearing body, and thus a high speed multicolor phenomenon can be realized.

Although the present invention has been described with respect to the specific embodiments shown, it is not limited thereto but only by the claims. For example, the above description is given on the assumption that a latent image bearing body such as a latent image bearing belt 1 is installed in the liquid developing apparatus of the present invention, but the present invention provides an electrostatic latent image formed on a latent image bearing body (such as a latent image bearing plate). It can also be applied to other types of liquid developing apparatus that do not include a latent image bearing body, such as developing onto this toner and completing the process. Those skilled in the art can understand that the embodiments can be changed or modified without departing from the spirit and scope of the invention.

In the liquid developing apparatus according to the first embodiment of the present invention, the toner cluster 22 is provided with the latent image bearing belt 1 from the recording electrode 17 of the recording head 13 by an electrostatic force depending on the potential in the electrostatic latent image. Is discharged onto the electrostatic latent image of the toner, and thus the toner cluster 22 is selectively discharged only above the colored portion. Therefore, the amount of carrier solvent attached to the latent image bearing belt 1 is greatly reduced, so that the transfer operation of the transfer roller 5 to remove excess carrier solvent on the latent image bearing belt 1 can be performed easily and accurately. have.

By selective toner cluster release, the amount of carrier solvent attached onto the latent image bearing belt 1 in the first color development is greatly reduced. Thus, the flow of the first color toner particles 23 onto the toner image of the second color can be prevented and thus color mixing between the first color toner image and the second color toner image can be prevented.

In the monochrome liquid developing apparatus according to the second embodiment of the present invention, the toner cluster 22 is selectively discharged only to the colored portions, so that the amount of carrier solvent attached on the latent image bearing belt 1 is greatly reduced and the latent image bearing belt ( 1) The transfer operation of the transfer roller 5 to remove the excess carrier solvent can be performed easily and accurately.

Similar to the first embodiment, by reducing the amount of carrier solvent attached onto the latent image bearing belt 1, the amount of carrier solvent transferred to the medium 7 in the phase transfer from the latent image bearing belt 1 to the medium 7 Is greatly reduced, so that flammable gas generation at the time of attachment can be avoided. A flammable gas recovery system is unnecessary and thus the liquid developer apparatus cost can be reduced.

In the liquid developing apparatus according to the third embodiment of the present invention, a film forming toner image of each color is formed on the latent image bearing belt 1 for each rotation of the latent image bearing belt 1. The electrostatic latent image for four colors is produced by only one pair of the charging section 2 and the exposure section 3. Therefore, the configuration of the liquid developing apparatus can be simplified as compared with the first embodiment, and thus the cost can be reduced.

Claims (37)

A liquid developing apparatus for developing an electrostatic latent image formed on a latent image bearing body to a visible toner image by using liquid toner in which toner particles are dispersed, Electrostatic latent image forming means for forming an electrostatic latent image on a surface of the latent image bearing body; When the carrier solvent of the liquid toner is reduced to a certain level, the charged toner cluster of the liquid toner having a property of forming a film on the latent image bearing body is discharged by using an electrostatic force depending on the potential of the electrostatic latent image. Toner cluster ejecting means for emitting a latent image and thereby developing the electrostatic latent image onto the visible toner image; And And a carrier solvent reducing means for reducing the carrier solvent on the visible toner such that dots on the visible toner are formed into a film on the latent image bearing body. The liquid developing apparatus according to claim 1, further comprising the latent image bearing body in which the latent electrostatic image is formed. The liquid developing apparatus according to claim 2, wherein the latent image bearing body is a latent image bearing belt. The liquid developing apparatus according to claim 2, wherein the latent image bearing body is a latent image bearing drum. 3. The liquid developing apparatus according to claim 2, further comprising image transfer means for transferring a toner image formed by a film on the latent image bearing body to a medium such as paper. The electrostatic latent image forming means of claim 1, Charging means for uniformly charging the surface of the latent image bearing body; And And exposure means for forming an electrostatic latent image on the surface of said latent image bearing body using light irradiation. The method according to claim 6, wherein the exposure means forms an electrostatic latent image on the surface of the latent image bearing body by irradiating the colored portion of the surface of the latent image bearing body, thereby removing the charge on the colored portion, And the toner cluster discharge means releases the toner cluster charged with the same polarity as the charge on the surface of the latent image bearing body. 7. The apparatus of claim 6, wherein the exposure means forms the electrostatic latent image on the surface of the latent image bearing body by irradiating an uncolored portion on the surface of the latent image bearing body, thereby removing the charge on the non-colored portion, And the toner cluster discharge means discharges the toner cluster charged at a polarity opposite to the charge on the surface of the latent image bearing body. A liquid developing apparatus according to claim 1, wherein said liquid developing apparatus is a multicolor liquid developing apparatus provided with at least two toner cluster ejecting means corresponding to each color. 10. The liquid developing apparatus according to claim 9, wherein the liquid developing apparatus such as the multicolor liquid developing apparatus is provided with four toner cluster ejecting means corresponding to yellow, magenta, cyan and black. The liquid developing apparatus according to claim 9, wherein Two or more charging means corresponding to each color to uniformly charge the surface of the latent image bearing body; And And at least two exposure means corresponding to each color are further provided to form an electrostatic latent image on the surface of the latent image bearing body using light irradiation. The method of claim 1, wherein the toner cluster discharge means, A plurality of write electrodes having convex emission points to which a development bias voltage is applied; And And a recording head including a plurality of toner liquid channel grooves for directing the liquid toner to an emission point of the recording electrode. 13. The liquid developing apparatus according to claim 12, wherein the recording electrodes of the recording heads are arranged at right angles to the moving direction of the latent image bearing body. 13. The liquid developing apparatus according to claim 12, wherein the recording head performs a scan movement on the latent image bearing body, and the recording electrodes of the recording head are arranged in parallel with the transfer direction of the latent image bearing body. 13. The colored portion of the latent electrostatic image of the latent image bearing body from the recording head by using an electrostatic force due to a potential difference between a developing bias voltage applied to the recording electrode and a potential on the latent electrostatic image. A liquid developing device, characterized in that it is released up. 13. The recording head as claimed in claim 12, wherein the recording head further comprises a plurality of electrophoretic electrodes installed in a liquid toner channel groove to which an electrophoretic voltage is applied such that toner particles of the liquid toner are transferred to an emission point by electrophoresis. Liquid developing apparatus characterized in that. 2. The apparatus of claim 1, wherein the carrier solvent reducing means includes a squeeze roller that presses the visible toner image from the visible toner image on the latent image bearing body to remove the carrier solvent and thereby form a dot on the visible toner into a film. Liquid developing apparatus characterized in that. 2. The apparatus of claim 1, wherein the carrier solvent reducing means comprises a heater that heats the visible toner phase from the visible toner image on the latent image bearing body to remove the carrier solvent and thereby form a dot on the visible toner into a film. Liquid developing apparatus characterized in that. 2. The apparatus of claim 1, wherein the carrier solvent reducing means comprises a fan that removes the carrier solvent from the visible toner image on the latent image bearing body by panning the visible toner image and thereby forming dots on the visible toner into a film. Liquid developing apparatus characterized in that. 13. The carrier solvent reducing means according to claim 12, wherein the carrier solvent reducing means makes the concentration of the particles of the liquid toner around the discharge point higher than a predetermined concentration, so that the percentage of toner particles on the visible toner on the latent image bearing body is predetermined. And a developing bias voltage controller for controlling a developing bias voltage applied to the recording electrode to be higher than a percentage of. 17. The carrier solvent reducing means according to claim 16, wherein the carrier solvent reducing means causes the concentration of the particles of the liquid toner around the discharge point to be higher than a predetermined concentration such that the percentage of toner particles on the visible toner on the latent image bearing body is predetermined. And an electrophoretic voltage controller for controlling the electrophoretic voltage applied to the electrophoretic electrode to be higher than the percent of. A liquid developing method in which an electrostatic latent image formed on a latent image bearing body using a liquid toner in which toner particles are dispersed is developed into a visible toner image, An electrostatic latent image forming step of forming an electrostatic latent image on a surface of the latent image bearing body; An electrostatic force that depends on the potential in the electrostatic latent image on the latent electrostatic latent image of the latent image bearing body is formed by the charged toner cluster of the liquid toner having a property of forming a film on the latent image bearing body when the carrier solvent of the liquid toner is reduced to a constant level. Toner cluster ejecting step by which the latent electrostatic image is developed into a visible toner image accordingly; And And a carrier solvent reducing step in which carrier solvent on the visible toner is reduced such that dots on the visible toner can be formed into a film on the latent image bearing body. 23. The liquid developing method according to claim 22, further comprising an image transfer step of transferring a toner image formed as a film on the latent image bearing body to a medium such as paper. The method of claim 22, wherein the latent electrostatic image forming step, A charging step in which the surface of the latent image bearing body is uniformly charged; And And an exposure step of forming the electrostatic latent image on the surface of the latent image bearing body by light irradiation. 25. The method of claim 24, wherein in the exposing step, the electrostatic latent image is formed on the surface of the latent image bearing body by irradiating a colored portion of the surface of the latent image bearing body, thereby removing the charge in the colored portion, And in the toner cluster discharging step, the toner cluster charged with the same polarity as the electric charge on the surface of the latent image bearing body is discharged. 25. The method of claim 24, wherein in the exposing step, the electrostatic latent image is formed on the surface of the latent image bearing body by irradiating an uncolored portion of the surface of the latent image bearing body, thereby removing the charge in the non-colored portion, And in the toner cluster discharging step, the toner cluster charged with a polarity opposite to the charge on the surface of the latent image bearing body is discharged. 23. The liquid developing method according to claim 22, wherein the electrostatic latent image forming step, the toner cluster ejecting step, and the carrier solvent reducing step are repeated N times (N: 2, 3, 4 ...) for N colors. Liquid developing method characterized in that the multi-color liquid developing method. 28. The liquid developing method according to claim 27, wherein said latent electrostatic image forming step, said toner cluster ejecting step, and said carrier solvent reducing step are repeated four times for yellow, magenta, cyan and black. 28. The liquid developing method according to claim 27, wherein said latent electrostatic image forming step, said toner cluster ejecting step, and said carrier solvent reducing step are repeated N times during one rotation of said latent image bearing body. The method of claim 22, wherein the toner cluster discharge step, A plurality of write electrodes having convex emission points to which a development bias voltage is applied; A liquid toner chamber for storing the liquid toner; And And a recording head including a plurality of liquid toner channel grooves for guiding the liquid toner to an emission point of the recording electrode. 31. The electrostatic latent image on the latent image bearing body from the recording head by an electrostatic force caused by a potential difference between the developing bias voltage applied to the recording electrode and the potential of the latent electrostatic image. Liquid developing method characterized in that it is released. 31. The electrophoretic method of claim 30, wherein the toner cluster ejecting step includes electrophoresis wherein an electrophoretic voltage is applied to the plurality of electrophoretic electrodes provided in the liquid toner channel grooves so that toner particles of the liquid toner are transferred to the discharge point by electrophoresis. And a voltage applying step. 23. The transfer step of claim 22, wherein the carrier solvent reduction step comprises: a transfer step of pressing the transfer roller to press the visible toner image on the latent image bearing body so that the carrier solvent is removed from the visible toner image and thus dots on the visible toner are formed into a film. Liquid developing method comprising a. 23. The method of claim 22, wherein reducing the carrier solvent comprises: heating a visible toner image on the latent image bearing body to remove the carrier solvent from the visible toner phase and thereby cause dots on the visible toner to be formed into a film. Liquid development method comprising a. 23. The method of claim 22, wherein reducing the carrier solvent comprises a panning step in which a visible toner image on the latent image bearing body is panned to remove the carrier solvent from the visible toner image and thereby cause dots on the visible toner to be formed into a film. Liquid development method comprising a. 31. The method of claim 30, wherein the reducing of the carrier solvent is such that the concentration of the toner particles of the liquid toner around the ejection point is higher than a predetermined concentration such that the percentage of toner particles on the visible toner on the latent image bearing body is predetermined. And a developing bias voltage controlling step of controlling a developing bias voltage applied to the recording electrode to be higher than a percentage. 33. The method of claim 32, wherein the reducing of the carrier solvent further comprises: wherein the concentration of the toner particles of the liquid toner around the ejection point is higher than a predetermined concentration such that the percentage of toner particles on the visible toner on the latent image bearing body is predetermined. And an electrophoretic voltage control step of controlling the electrophoretic voltage applied to the electrophoretic electrode to be higher than a percentage.