KR100396576B1 - Developing apparatus of liquid electrophotographic image forming device - Google Patents

Abstract

A developing apparatus of a wet electrophotographic image forming apparatus is disclosed. The disclosed developing apparatus includes a developing container accommodating a developer; A developing roller installed to rotate to face the photosensitive member while a part of the developer in the developing container is locked; Deposit means for attaching a developer to an outer circumferential surface of the developing roller; A metering blade for regulating the developer attached to the outer circumferential surface of the developing roller by the deposit means to a thickness within a predetermined range; And a squeeze roller which is installed to rotate in contact with the outer circumferential surface of the developing roller and presses the developer layer on the developing roller that has passed through the metering blade to a predetermined pressure. Therefore, the developer layer on the developing roller can be made dense and uniform, and the concentration of the developer layer required for the development can be increased.

Description

Developing apparatus of liquid electrophotographic image forming device

The present invention relates to a wet electrophotographic image forming apparatus, and more particularly, to a developing apparatus of a wet electrophotographic image forming apparatus using a high concentration of liquid developer.

In general, a wet electrophotographic image forming apparatus scans a photosensitive member to form an electrostatic latent image corresponding to a desired image, and then develops the image by using a developer mixed with a powdered toner and a liquid solvent. It is a device to print on.

1 illustrates a developing apparatus of such a wet electrophotographic image forming apparatus, which is disclosed in US Pat. No. 5,255,058.

Referring to the drawings, the developing apparatus of the wet electrophotographic image forming apparatus scans the photosensitive member 10 charged with a predetermined voltage by the charger 14 and the charged photosensitive member 10 to detect a relative voltage difference. And a developer supply unit for developing the electrostatic latent image by supplying a developer to the photosensitive member 10 to form the electrostatic latent image of a desired image by forming the electrostatic latent image of the desired image. And a transfer body 30 which receives the image and prints it on the paper 72.

The developer supply unit usually prepares a developer having a toner concentration of 3% solids or less and supplies it between the photosensitive member 10 and the developing roller 38. To this end, the developer supply unit includes concentrated cartridges 82 and 84 containing a concentrated developer having a toner concentration of about 25% solid, a solvent cartridge 86 containing pure solvent, and a mixture of about 2 to 3% solid. A mixing tank (55, 57, 59, 61) for preparing a developer having a uniform concentration of and a developer (90, 92, 94, 96) prepared in the mixing tank (55, 57, 59, 61). A supply unit 20 pumped in and supplied to the developing roller 38 and a recovery unit for recovering excess developer remaining after developing the electrostatic latent image are provided. In addition, the recovery unit collects the developer flowing down after being supplied to the developing roller 38 and the photoconductor 10 and the collecting container 50 to return to the mixing tank (55, 57, 59, 61) for each color; Then, the squeeze roller 26 compresses the photosensitive member 10 on which the image is developed and squeezes the solvent contained in the developed image, and the squeezed developer is recovered through the collection container 50 to separate the toner. The solvent includes a separator 66 or the like that is sent to the solvent tank 65.

In order to perform the developing operation in the above configuration, first, a developer corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) is mixed in each of the mixing tanks 55, 57, 59,61) at a concentration of 2-3% solids. Of course, if a system develops with only a single color, such as black and white, only one developer needs to be prepared, but here, a system in which all four color developers are prepared to realize a color image is disclosed. In order to prepare the developer for each of these colors, the developer supply unit, the concentrated developer and the pure solvent from the concentrated cartridge 82, 84 and the solvent cartridge 86 into the mixing tank (55, 57, 59, 61), respectively. Supply to produce a developer of the corresponding concentration. To this end, each of the mixing tanks 55, 57, 59, and 61 is typically equipped with a concentration sensor (not shown) to measure the concentration of the developer to be mixed. When the developer is prepared as described above, the developing operation is started. First, the charger 14 charges the photosensitive member 10 to a predetermined potential. In this state, the optical scanning device 16 scans the charged photoconductor 10 with light to lower the potential to form an electrostatic latent image corresponding to a desired image. Subsequently, the pumps 90, 92, 94 and 96 are operated to supply the developer prepared in the mixing tanks 55, 57, 59 and 61 between the developing roller 38 and the photosensitive member 10 through the supply unit 20. While developing the electrostatic latent image. The image developed in this way is once transferred to the transfer roller 30, and if the image is composed only of the color is directly taken on the paper 72 in this state. However, in the case of implementing a color image by superimposing a plurality of colors of developer, the steps of charging, exposing, and developing as described above are carried out in four steps of yellow (Y), magenta (M), cyan (C), and black (K). Repeatedly performed for each color, the image developed for each color is superimposed on the transfer roller 30. Then, the overlapped color image is printed on the paper 72 which is passed between the pressing rollers 71.

By the way, as described above, such a developing device has a considerably complicated structure required from the preparation of the developer to the supply and recovery of the developer. This problem is caused by not using the concentrated developer in the concentrated state directly, but using it as a low concentration developer of 3% solid or less. Of course, when the developer is used in such a low concentration, fluidity is improved. There is an advantage that the density variation of the toner becomes smaller for each part of the developed image. However, as described above, the concentrated developer and the solvent are prepared in each of the cartridges 82, 84 and 86, and then sent to the mixing tanks 55, 57, 59, and 61, and the concentration is less than 3% solid for development. The overall size of the device is such that zero mixing, developing the electrostatic latent image, and then squeezing and recovering the solvent contained in the developed image to obtain a high concentration suitable for printing again. In terms of costs and costs, a lot of burdens are involved. Therefore, there is a need for a developing apparatus of a wet electrophotographic image forming apparatus of a new method that can solve this problem.

SUMMARY OF THE INVENTION The present invention has been devised in view of the above necessity, and an object thereof is to provide a developing apparatus of a high density wet electrophotographic image forming apparatus, in particular, by improving the quality of an image by constantly regulating a developer on a developing roller.

1 is a view showing a developing apparatus of a conventional wet electrophotographic image forming apparatus.

2 illustrates a developing apparatus of a wet electrophotographic image forming apparatus according to the present invention;

3 shows a developer layer on a development roller attached by deposit means.

4 is a view showing a developer layer on a developing roller after passing through the metering blade.

5 is a view showing a developer layer on a developing roller after passing through a squeeze roller;

<Description of the symbols for the main parts of the drawings>

100 ... Developing container 102 ... Concentrated liquid developer

104 ... developing roller 106 ... depository controller

108 ... Metering Blade 110 ... Cleaning Roller

112 ... deposit power supply 114 ... development power supply

115 ... Agitator 120 ... Squeeze Roller

127 ... Daejeon Roller 129 ...

200 ... photosensitive member 300 ... transfer belt

N ... developing nip

In order to achieve the above object, the developing apparatus of the wet electrophotographic image forming apparatus according to the present invention,

A developing container accommodating a developer; A developing roller installed to rotate to face the photosensitive member while a part of the developer in the developing container is locked; Deposit means for attaching a developer to an outer circumferential surface of the developing roller; A metering blade for regulating the developer attached to the outer circumferential surface of the developing roller by the deposit means to a thickness within a predetermined range; And a squeeze roller which is installed to rotate in contact with the outer circumferential surface of the developing roller and presses the developer layer on the developing roller that has passed through the metering blade to a predetermined pressure.

Here, it is preferable that the squeeze roller is made of SUS material or urethane material, and the line pressure applied by the squeeze roller in contact with the outer circumferential surface of the developing roller is preferably 120 kgf / cm to 250 kgf / cm. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 shows a developing apparatus of a wet electrophotographic image forming apparatus according to the present invention. Referring to the drawings, the developing apparatus is provided with a developing container 100 for receiving and receiving a liquid developer from a developer cartridge (not shown). Here, as the developer supplied to the developing container 100, a high concentration liquid developer 102 in a 3 to 40% solid range is used.

In the developing container 100, a developing roller 104 which rotates to face the photosensitive member 200 while a part of the developer 102 is locked, and a developer are attached to an outer circumferential surface of the developing roller 104. And a metering blade 108 for regulating the developer attached to the outer circumferential surface of the developing roller 104 by a deposit means to a thickness within a predetermined range. A squeeze roller 120 for pressurizing the developer layer passing through the blade 108 to a predetermined pressure, and a cleaning roller for cleaning the outer circumferential surface of the developing roller 104 after developing an image formed on the photosensitive member 200 ( 110 is provided.

The developing roller 104 is a conductive elastomer (elastomer), the material is made of polyurethane rubber (polyurethane rubber) or NBR.

The deposit means includes a deposit controller 106 installed to contact the developer roller 104 or maintain a constant gap, and a deposit power supply 112 for applying a voltage to the deposit controller 106. . The deposit controller 106 attaches the developer to the outer circumferential surface of the developing roller 104 by the electrostatic force of the voltage applied from the deposit power supply 112 in a state of being locked in the developer 102, and made of stainless material. It is.

The metering blade 108 is in contact with the outer circumferential surface of the developing roller 104 to regulate the developer on the developing roller 104 attached by the depositing means so as to have a uniform thickness in a predetermined range. It is composed of metal plate.

The squeeze roller 120 is installed to rotate in contact with the outer circumferential surface of the developing roller 104 between the metering blade 108 and the developing nip N, thereby pressing the outer circumferential surface of the developing roller 104 to a predetermined pressure. The developer layer passed through the ring blade 108 is made into a dense and uniform layer. Here, the squeeze roller 120 has a diameter of about 5 mm, preferably made of SUS material or urethane (urethane) material, the line pressure applied to the outer peripheral surface of the developing roller is substantially 120kgf / cm ~ 250 It is preferable that it is kgf / cm. On the other hand, the squeeze roller 120 may be passively rotated by a frictional force with the rotating developing roller 104, but may be rotated independently by other driving means, the rotational speed is depending on the state of the developer layer Can be variable.

After the cleaning roller 110 is in contact with the developing roller 104 and rotated in the same direction, the image formed on the photosensitive member 200 by the optical scanning device 129 is developed through the developing nip N, and then developed. The developer remaining in the undeveloped state on the roller 104 is removed.

In the drawing, reference numeral 114 denotes a developing power supply for applying a developing voltage to the developing roller 104, and reference numeral 115 denotes an agitator for maintaining the developer in the developing container 100 at a uniform concentration. Reference numeral 127 denotes a charging roller that charges the photosensitive member 200, and reference numeral 300 denotes a transfer belt which transfers an image developed on the photosensitive member 200 and prints it on a sheet of paper.

Only one such developing device may be provided in an image forming apparatus using a single color. However, in the case of a color image forming apparatus for printing a plurality of colors, the developing apparatus is provided for each color.

In the above configuration, in order to perform the developing operation, the developer is first supplied from the developer cartridge to the developing container 100 up to a predetermined level. Here, the developer supplied to the developing container 100 is the high concentration liquid developer 102 in the range of 3 to 40% as described above. Next, voltages of 300 to 550 V and 500 to 1500 V are applied to the developing roller 104 and the deposition controller 106, respectively. When the toner particles in the developer have a positive charge, the developer adheres to the surface side of the developing roller 104 due to the voltage difference between the two rollers 104 and 106 when the above voltage is applied. By the way, the developer attached to the developing roller 104, as shown in Figure 3 because the amount is larger than the amount required to develop the electrostatic latent image formed on the photosensitive member 200, as well as the variation in concentration is large. It is difficult to develop an image of uniform density.

Accordingly, the metering blade 108 presses the developer on the developing roller 104 attached by the depositing means to regulate the uniform thickness in a predetermined range. Accordingly, the concentration of the developer layer passing through the metering blade 108 becomes relatively higher than before passing through the metering blade 108. This metering blade 108 serves to equalize the mass per unit area of the developer layer when a high concentration developer in the range of 3-40% solids (preferably 3-14% solids) is used. However, as shown in FIG. 4, the developer layer passing through the metering blade 108 is inflated by the physical repulsive force of the toner particles 150 in the uppermost layer, and also the metering blade 108 and the development. Influence of the surface condition of the roller 104 causes problems such as unevenness of developer layers and generation of streaks. This in turn lowers the quality of the image formed on the photoconductor 200.

In order to solve this problem, the squeeze roller 120 rotating in contact with the developing roller 104 presses the developer layer on the developing roller 104 which has passed through the metering blade 108 to uniform the developer layer. The carrier remaining in the developer layer is removed. At this time, the rotation speed of the squeeze roller 120 may vary depending on the state of the developer layer. Therefore, as shown in FIG. 5, the developer layer after passing through the metering blade 108 can be made more dense and uniform, and the concentration of the developer layer required for development can be increased.

Next, the electrostatic latent image formed on the photosensitive member 200 through the developing nip N is developed by the developer layer on the developing roller 104 passing through the squeegee roller 120.

Then, the developer remaining on the developing roller 104 after development is removed by the cleaning roller 110.

On the other hand, the image transferred to the photosensitive member 200 is transferred to the transfer belt 300, if the image consisting of only the color is taken directly on the paper in this state. However, in the case of realizing a color image, after superimposing the developed image through the developing apparatus for each of the four colors of yellow (Y), cyan (C), magenta (M), and black (K) on the transfer belt, It will be printed on paper.

As described above, the developing apparatus of the wet electrophotographic image forming apparatus according to the present invention includes a squeeze roller which rotates in contact with the developing roller, thereby passing through the metering blade, and then applying the developer layer attached on the developing roller. It can be made more uniform and dense, and can also increase the concentration of the developer layer required for development. Therefore, the quality of the image formed on the photosensitive member can be improved.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary and will be understood by those skilled in the art that various modifications are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (3)

A developing container accommodating a developer; A developing roller installed to rotate to face the photosensitive member while a part of the developer in the developing container is locked; Deposit means for attaching a developer to an outer circumferential surface of the developing roller; A metering blade for regulating the developer attached to the outer circumferential surface of the developing roller by the deposit means to a thickness within a predetermined range; And And a squeeze roller which is installed to rotate in contact with an outer circumferential surface of the developing roller and pressurizes the developer layer on the developing roller passed through the metering blade to a predetermined pressure. Developing device. The method of claim 1, The squeeze roller is a developing device of a wet electrophotographic image forming apparatus, characterized in that made of SUS material or urethane material. The method of claim 1, And a line pressure applied by the squeeze roller in contact with the outer circumferential surface of the developing roller is substantially 120 kgf / cm to 250 kgf / cm.