KR100243215B1 - Development apparatus for a liquid electrophotographic printer - Google Patents

Abstract

Disclosed is a developing apparatus of a wet electrophotographic printer in which the structure thereof is improved to more effectively remove excess developer attached to the photosensitive belt. The disclosed development apparatus includes: a developing roller for attaching a developer to a photosensitive belt passing through an upper portion thereof, a primary squeeze roller for removing excess developer from a developer attached to the photosensitive belt to form a developer film on the photosensitive belt, and a wrap-around A developing apparatus for a wet electrophotographic printer comprising a secondary squeeze roller for removing excess developer that has returned to both ends of the primary squeeze roller by development; By charging the surface of the secondary squeeze roller to a predetermined polarity, it is characterized in that the charging means for transferring the developer attached to the photosensitive belt to the surface of the secondary squeeze roller by the electric force. Therefore, in the developing apparatus according to the present invention, the removal efficiency of the extra developer attached to the photosensitive belt is increased by the electric force between the surface of the secondary squeeze roller and the extra developer.

Description

Developing apparatus for wet electrophotographic printer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet electrophotographic printer, and more particularly to a developing apparatus for a wet electrophotographic printer with improved means for removing excess developer.

In general, an electrophotographic printer such as a laser printer forms a latent electrostatic image on a photosensitive medium such as a photosensitive drum or a photosensitive belt, develops the electrostatic latent image with a toner having a predetermined color, and transfers the image to a recording sheet. It is a device for obtaining a desired image. Laser printers are largely classified into wet and dry, depending on the toner used. In a wet laser printer, a developer in which a toner is mixed in a volatile liquid carrier is used. The wet laser printer using the developer has better print quality than the dry laser printer using the powder toner, and can prevent damage caused by harmful toner dust, and its use is gradually increasing.

1 is a schematic view showing the main structure of a wet laser printer as one type of a conventional electrophotographic printer.

As shown, a conventional general wet laser printer has a photosensitive belt 110 in an orbit, a primary roller 121, a secondary roller 122, and a tertiary which circulate the photosensitive belt 110 in a given path. Three rollers of the roller 123 are provided. Infinite orbits of the photosensitive belt 110 are maintained by the three rollers 121, 122, and 123. In general, the tertiary roller 123 is driven by a driving motor (not shown) to rotate the photosensitive belt 110. The power transmission body, the secondary roller 122 is a steering roller (Steering roller) to prevent the meandering by adjusting the tensile force of the photosensitive belt (110). In addition, a main charging unit 135 for uniformly charging the photosensitive belt 110 is provided at one side of the photosensitive belt 110, and a photosensitive belt 110 of a portion corresponding to the given data is provided below the photosensitive belt 110. LSU (Laser scanning unit, 130) for irradiating a laser beam to form an electrostatic latent image, and a developer containing a toner having a predetermined color to a region of the photosensitive belt 110, the electrostatic latent image is formed A developing device 140 for developing the device is installed. In particular, in the case of a color printer, a plurality of developing devices 140 are provided to separately contain a plurality of LSUs 130 and a developer having a plurality of colors for color combinations.

In this case, the main charging unit 135 charges the surface of the photosensitive belt 110 to have a positive charge, and the LSU 130 selectively electrostatically discharges the positive charge on the surface of the photosensitive belt 110 to prevent an electrostatic latent image. Since it is formed, a predetermined potential difference is generated between the electrostatic latent image portion and the surface of the photosensitive belt 110 around it. Therefore, when the developer 140, which is generally charged with a positive charge, is supplied to the surface of the photosensitive belt 110, the developer is selectively attached only to an area where an electrostatic latent image is formed due to a potential difference, and finally toner Will form an image.

As such, the toner image formed on the electrostatic latent image of the photosensitive belt 110 by the developing device 140 is recorded by the transfer roller 124 installed in parallel with the primary roller 121 with the photosensitive belt 110 interposed therebetween. Is transferred to 126. The recording paper 126 is supplied between the transfer roller 124 and the pressure roller 125 installed in parallel with a predetermined interval therebetween, and the toner image transferred to the recording paper 126 is separated as described above. It is fixed by a fixing device (not shown) to finally obtain a desired image.

2 is a schematic view showing the internal structure of the conventional developing apparatus shown in FIG.

Referring to FIG. 2, in general, the developing apparatus 140 is installed directly under the photosensitive belt 110. In the developing device 140, a developer 148 made of a toner having a predetermined color and a liquid carrier is contained, and a developing roller 141, a cleaning roller 142, and a squeeze roller 144, 146 are provided thereon. have.

The developer roller 141 serves to attach the developer 148 to a region of the photosensitive belt 110 in which an electrostatic latent image is formed by the LSU 130, wherein the developer 148 is a developer supply device. 143 is supplied to the surface between the developing roller 141 and the photosensitive belt 110. The cleaning roller 142 removes the developer 148 remaining on the surface of the developing roller 141.

The squeegee roller (Squeegee roller, 144, 146) is composed of the first squeeze roller 144 and the second squeeze roller 146, and used in the phenomenon of the electrostatic latent image of the developer 148 attached to the photosensitive belt 110 Remove excess developer 148. Thus, the developer 148 removed from the photosensitive belt 110 is attached to the surfaces of the squeeze rollers 144 and 146, and again the primary blades 145 and the secondary blades 147 provided under the squeeze rollers 144 and 146. Removed and stored in the developing device 140 inside.

As described above, the developer 148 attached to the electrostatic latent image region of the photosensitive belt 110 passes through the squeeze rollers 144 and 146 and is removed while leaving only the amount necessary for developing the electrostatic latent image to form a thin developer film. Since the developer film contains a liquid carrier unnecessary for development, it is necessary to remove it. The removal of the liquid carrier is installed in parallel with the tertiary roller 123 at predetermined intervals and by a dry roller 171 heated by a separately provided heat roller 172. Is done. The heated dry roller 171 as described above absorbs the liquid carrier on the surface of the photosensitive belt 110 to dry the developer film so that only the toner remains in the latent electrostatic image. Herein, the liquid carrier absorbed by the dry roller 171 is heated by the heat roller 172 to be evaporated and removed.

The developing system of the wet electrophotographic printer as described above will be described in more detail with reference to FIGS. 3 and 4. 3 is a schematic view of a developing system of an electrophotographic printer, and FIG. 4 is a plan view of the developing system shown in FIG.

3 and 4 together, the developing roller 141 maintains a predetermined distance from the photosensitive belt 110 and rotates in the same direction as the traveling direction of the photosensitive belt 110, and the developer (supplied therebetween) 148 is attached to the area where the electrostatic latent image of the photosensitive belt 110 is formed. At this time, in order to adhere to the electrostatic latent image, the developer 148 is generally charged to have a positive charge as described above. The developing solution 148 attached to the photosensitive belt 110 as described above forms the developing region 115 equal to the width of the developing roller 141, and the primary squeeze roller 144 is in progress along the photosensitive belt 110. ), Only the amount necessary for development is left, and the extra developer 148 is removed.

The primary squeeze roller 144 rotates in the same direction as the traveling direction of the photosensitive belt 110 during development, and removes the excess developer 148 from the developer 148 to form a thin developer film 149. . At this time, some of the extra developer 148 is not removed, and wrap-around is passed to the secondary squeeze roller 146 around the both ends of the primary squeeze roller 144 without leaving the developing region 115. Develop 150. As described above, the wrap-around developer 151 passed by the wrap-around developer 150 is removed by the secondary squeeze roller 146 rotating in the opposite direction to the traveling direction of the photosensitive belt 110. The removed wrap-around developer 151 is attached to the surface of the secondary squeeze roller 146, and is separated and recovered by the secondary blade 147 installed in contact with the surface of the secondary squeeze roller 146. do.

However, the developing apparatus of the conventional wet laser printer constructed and operated as described above has the following problems. That is, the developer outside of the image region that has been turned over to the secondary squeeze roller 146 by the wrap-around phenomenon is removed by the secondary squeeze roller 146, in which the developer is reversely rotated with the moving direction of the photosensitive belt 110. Since it is removed only by the rotational force of the primary squeeze roller 146, the sufficient removal is not made. As such, when the developer 148 is not sufficiently removed and a large amount remains, the dry roller 171 absorbs a large amount of liquid carrier and is easily saturated in the drying process by the dry roller 171 and the heat roller 172. After that, the developer 148 may not be sufficiently dried. In addition, when the developer 148 that is not dried remains on the photosensitive belt 110, an incomplete transfer is made and colors may overlap. In addition, the inside of the printer is easily contaminated, and the recovery rate of the developer 148 is also reduced.

The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide a developing apparatus of a wet electrophotographic printer having an improved structure so that the excess developer attached to the photosensitive belt can be more sufficiently removed. There is this.

1 is a schematic diagram showing the main structure of a conventional electrophotographic printer;

2 is a schematic view showing an internal structure of the developing apparatus shown in FIG. 1;

3 is a side view showing an outline of a developing system of an electrophotographic printer;

4 is a plan view of the developing system shown in FIG. 3;

5 is a perspective view showing an embodiment of a developing apparatus according to the present invention;

6 is a side view showing an outline of a developing system according to the embodiment shown in FIG. 5;

7 is a perspective view showing another embodiment of the developing apparatus according to the present invention;

8 is a side view showing an outline of a developing system according to the embodiment shown in FIG.

<Explanation of symbols for main parts of drawing>

110 ... photosensitive belt 115 ... development area

121 ... 1st roller 122 ... 2nd roller

123 ... 3rd roller 124 ... Transfer roller

125 ... Pressure Roller 126 ... Record

130 ... LSU 135 ... Jeongdae Electric

140 Developing unit 141 Developing roller

142 ... cleaning roller 143 ... developer

144 ... Primary Squeeze Roller 145 ... Primary Blade

146 ... 2nd squeeze roller 147 ... 2nd blade

148 Developing Solution 149

150 ... wrap-around developer 151 ... wrap-around developer

171 ... Dry Roller 172 ... Hit Roller

560,760 ... 2nd squeeze roller 561,761 ... roller shaft

562 ... Roller outer 563 ... Roller inner

565.Electric circuit 765.Friction member

In order to achieve the above object, a developing apparatus of a wet electrophotographic printer according to the present invention includes: a developing roller containing a developer therein and attaching the developer to a photosensitive belt passing through the upper portion thereof, and attached to the photosensitive belt. A primary squeeze roller to remove excess developer from the developer to form a developer film on the photosensitive belt, and a secondary squeeze roller to remove excess developer returned to both ends of the primary squeeze roller by a wrap-around development. A developing apparatus for a wet electrophotographic printer; Charging means for charging the surface of the secondary squeeze roller to a predetermined polarity, so that the developer attached to the photosensitive belt is transferred to the surface of the secondary squeeze roller by electrical force.

Here, the secondary squeeze roller has a roller shell made of a conductor and a roller shell made of an insulator which electrically insulates the roller sheath and the roller shaft from each other between the roller shell made of the conductor and the power supply means. It is preferable that the charging circuit is connected to the positive electrode or the negative electrode to the roller shell from the negative electrode or the positive electrode opposite to the pole connected to the roller shell to the predetermined charge polarity to the roller shell.

In addition, the charging means is installed in contact with the surface of the secondary squeeze roller, by charging the surface of the secondary squeeze roller to generate a static electricity by friction with the surface of the secondary squeeze roller to charge the surface of the secondary squeeze roller to a predetermined polarity It is preferably a friction member.

Therefore, in the developing apparatus according to the present invention, the removal efficiency of the extra developer attached to the photosensitive belt is increased by the electric force between the surface of the secondary squeeze roller and the extra developer.

Hereinafter, a preferred embodiment of a developing apparatus of a wet electrophotographic printer according to the present invention will be described in detail with reference to the accompanying drawings.

<Example 1>

FIG. 5 is a perspective view showing a structure and a charging circuit of a secondary squeeze roller, showing an embodiment of a developing apparatus according to the present invention.

According to FIG. 5, the secondary squeeze roller 560 in the developing apparatus according to the present invention has a roller endothelial 563 that surrounds the outside of the roller shaft 561 and the outside of the roller endothy 563. It has a double structure of surrounding roller shell 562. In other words, a non-conductive roller inner shell 563 is provided between the roller shaft 561 as a conductor and the roller shell 562. Accordingly, the non-conductive roller inner shell 563 electrically insulates the roller outer shell 562 and the roller shaft 561 from each other.

In addition, a charging circuit 565 is provided to charge the roller envelope 562 with a predetermined polarity (polarity opposite to that of a developer having a generally positive charge). Thus, the charging circuit 565 is configured by connecting the positive electrode of the power supply and the roller shaft 561, and the negative electrode of the power supply and the roller shell 562. However, when the developer has a negative charge, the polarity of the charging circuit 565 is reversed.

The role of the charging circuit 565 configured as described above will be described in detail with reference to FIG. 6. FIG. 6 is a side view showing an outline of a developing system according to the embodiment shown in FIG. 5, wherein the same reference numerals as in the above-described drawing indicate the same components.

The developing apparatus according to the present embodiment is installed directly under the photosensitive belt 110 and includes a primary squeeze roller 144 and a secondary squeeze roller 560. As described above, the developer 148, which is normally charged with a positive charge by a developing roller (not shown), is attached to the surface of the photosensitive belt 110. In the developer 148 attached to the photosensitive belt 110, the excess developer 148 except for the amount necessary for development is removed by the primary squeeze roller 144 to form a thin developer film 149. At this time, the wrap-around developer 151 which has returned both ends of the primary squeeze roller 144 by the wrap-around phenomenon is removed by the secondary squeeze roller 560.

Here, the surface of the secondary squeeze roller 560 is charged with a negative charge. That is, since the roller shaft 561 connected to the positive pole of the power supply by the charging circuit 565 and the roller envelope 562 connected to the negative pole of the power supply are insulated from each other by the non-conductive roller inner shell 563, the roller shaft 561 ) Is positively charged and the roller sheath 562 is negatively charged.

As described above, since the surface of the secondary squeeze roller 560 and the wrap-around developer 151 attached to the photosensitive belt 110 are charged with different charges, mutual electrical attraction is applied to the wrap-around developer 151. Is more easily transferred from the photosensitive belt 110 to the surface of the secondary squeeze roller 560. That is, since the rotational force and the electrical force of the secondary squeeze roller 560 act on the wrap-around developer 151, its removal efficiency is higher than in the related art.

Then, the wrap-around developer 151 transferred from the photosensitive belt 110 to the surface of the secondary squeeze roller 560 is separated from the surface of the secondary squeeze roller 560 by the secondary blade 147 and recovered. .

<Example 2>

FIG. 7 is a perspective view showing another embodiment of the developing apparatus according to the present invention, wherein the friction member is installed in contact with the surface of the secondary squeeze roller.

According to Figure 7, the friction member 765 is installed in contact with the surface of the secondary squeeze roller 760 in the developing apparatus according to the present invention. The friction member 765 generates static electricity by friction with the surface of the secondary squeeze roller 760 that rotates about the roller shaft 761, thereby causing the surface of the secondary squeeze roller 760 to have a predetermined polarity (usually Polarity opposite to the developer having a positive charge).

In general, static electricity is generated between two friction objects. For example, when the fur and glass rub against each other, the fur is charged with positive charge and the glass is charged with negative charge. When the glass and bismuth rub with each other, the glass is charged with positive charge and the bismuth is charged with negative charge. In addition, when bismuth and ebonite rub against each other, bismuth is charged with positive charge and ebonite is charged with negative charge. In this way, the charges charged to each other are determined according to the materials of the two objects rubbing against each other, and the tendency of gradually charging negative charges in the order of fur, glass, bismuth, and ebonite becomes stronger. Therefore, it is preferable that the surface material of the secondary squeeze roller 760 uses ebonite having a strong tendency to be charged with negative charge, and the material of the contact portion with the surface of the secondary squeeze roller 760 of the friction member 765 is Preference is given to using fur, glass or bismuth.

FIG. 8 is a side view illustrating an outline of a developing system using a secondary squeeze roller provided with a friction member shown in FIG. 7.

The developing apparatus according to the present embodiment is installed directly under the photosensitive belt 110 and includes a primary squeeze roller 144 and a secondary squeeze roller 760. As in Example 1 described above, the primary squeeze roller 144 removes the excess developer 148 attached to the surface of the photosensitive belt 110 to form a thin developer film 149. Then, the wrap-around developer 151 that has returned both ends of the primary squeeze roller 144 by the wrap-around phenomenon is removed by the secondary squeeze roller 760.

Here, since the secondary squeeze roller 760 is rotated in a direction opposite to the traveling direction of the photosensitive belt 110, the surface of the secondary squeeze roller 760 is in continuous friction with the friction member 765. At this time, as described above, the surface of the secondary squeeze roller 760 made of ebonite is charged with negative charge, and the friction member is charged with positive charge. Therefore, since the mutual attraction between the surface of the negatively charged secondary squeeze roller 760 and the positively charged wrap-around developer 151 acts, the wrap-around developer 151 is more easily exposed to the photosensitive belt. It is transferred from 110 to the surface of the secondary squeeze roller 760.

Then, the wrap-around developer 151 transferred from the photosensitive belt 110 to the surface of the secondary squeeze roller 760 is separated from the surface of the secondary squeeze roller 760 by the secondary blade 147 and recovered. .

As described above, according to the present invention, since the removal efficiency is increased by the electrical attraction due to the wrap-around phenomenon, the developing solution of the liquid carrier absorbed by the dry roller in the drying process by the dry roller and the heat roller. Since the amount is reduced to be sufficiently evaporated and removed by the heat roller, it is possible to completely dry the developer film attached to the photosensitive belt.

The charging means in the embodiment as described above is merely exemplary, and those skilled in the art will be able to select or modify various charging means in order to fully understand the technical idea of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the claims by the technical spirit described above.

As described above, in the developing apparatus of the wet electrophotographic printer according to the present invention, the surface of the secondary squeeze roller is charged with a polarity opposite to that of the developer, thereby reducing the electrical force between the surface of the secondary squeeze roller and the extra developer. As a result, the removal efficiency of the excess developer attached to the photosensitive belt is increased. In addition, the recovery rate of the developing solution is increased, and the drying of the developing film by the dry roller is also sufficiently performed. Therefore, the transfer can be surely performed, thereby obtaining an image having improved quality.

Claims (4)

A developer roller containing the developer therein, the developer roller attaching the developer to the photosensitive belt passing through the upper portion, and a primary squeeze roller to remove the developer from the developer attached to the photosensitive belt to form the developer film on the photosensitive belt. And a secondary squeeze roller for removing excess developer that has returned to both ends of the primary squeeze roller by a wrap-around development. Wet electrophotographic method characterized in that the charging means for charging the surface of the secondary squeeze roller to a predetermined polarity, so that the developer attached to the photosensitive belt is transferred to the surface of the secondary squeeze roller by electrical force The developing device of the printer. The method of claim 1, The secondary squeeze roller has a roller sheath made of a conductor and a roller sheath made of a non-conductor which electrically insulates the roller sheath and the roller shaft from each other between a roller sheath made of a conductor, and the charging means is connected to the roller from a power source. An electrostatic circuit of a wet electrophotographic printer, characterized in that a charging circuit connects an anode or a cathode to the outer shell and a cathode or an anode opposite to the pole connected to the roller outer shell to the roller shaft. Developing device. The method of claim 1, The charging means is installed in contact with the surface of the secondary squeeze roller, the friction member for charging the surface of the secondary squeeze roller to a predetermined polarity by generating static electricity by friction with the rotating secondary squeeze roller surface A developing device for a wet electrophotographic printer, characterized in that. The method of claim 3, The surface material of the secondary squeeze roller is ebonite, and the contact portion of the friction member with the surface of the secondary squeeze roller is any one of a group consisting of fur, glass, and bismuth. Device.

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