JPH0545995A - Developing method by color developer - Google Patents

Abstract

PURPOSE:To attain improvement of reliability and high speed development without having color turbidity by supplying a prescribed color developer to plural developing rollers moving in the reverse direction of an electrostatic latent image carrier, and applying a bias voltage. CONSTITUTION:In a developing part 4, an arm 6 is rotated for time till an electrostatic latent image comes, the former developing roller 5 is removed from a photosensitive drum 1, and the next developing roller 5 is made an approach and rotated in the opposite direction of the photosensitive drum 1, so as to apply the bias voltage suitable for the development. When the electrostatic latent image is moved to the developing part 4 having preparations such that, a developer flows out from a developer supplying part 8. The photosensitive drum 1 completing the development, reaches a transfer part 9 via a pretransfer image adjusting roller 12, and performs a transfer on a transfer sheet on a transfer drum 10. These developing rollers 5 are prepared for each color, so that even if the scratching of toner remaining on the surface of a roller is insufficient, or even if a liquid drops from both ends of the roller, an operation is continued without paying attention.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is more reliable and more reliable than conventional liquid multicolor color developing methods in color copying machines or printers and does not cause problems such as color turbidity in continuous use. , A development method aiming at low manufacturing cost by a simple mechanism capable of high-speed development.

[0002]

2. Description of the Related Art As a method for producing a color image by electrophotography, generally, an electrostatic latent image is formed on the surface of a photoconductor by an optical image obtained by color-separating a color original by the additive three-primary color method. The color originals are reproduced by developing with color toners of the three primary colors corresponding to the subtractive color method and superposing them on an image support surface such as paper. In this developing step, the small particle size of the toner used is an important condition for increasing the definition of the image and obtaining a beautiful image. Means for developing an electrostatic latent image can be roughly classified into a dry method and a wet method. In the dry development method, the particle size of the toner is inevitably increased because the powder toner is used, and the resolution of the image is lowered because the toner images of respective colors superposed on the image support are mixed and fixed by heat pressure fixing, Although there is a problem in image quality, at present, in color electrophotographic copying machines and printers, handling is simpler than in the wet method.
The dry development method is adopted because it is easy to maintain.

However, considering the output in electronic publishing and the development of color image creation by electrophotographic technology in the fields of simple printing and photofinishing in the future market, this problem of image quality is important. , Efforts to solve the current problems are considered essential. Efforts to find a solution are problems in the development of a dry development method using fine particle toner and the above-mentioned wet development method. Easy handling, easy maintenance, high-speed correspondence and miniaturization. It is also focused on development that enables low manufacturing costs.

One example is the published patent WO 90/14619, in which a photosensitive drum having an electrostatic latent image is placed in a conventional container containing a developing electrode and containing a developing solution. Unlike the method of dipping and developing, which is a major obstacle when considering color change, whether the mechanism is simple, and ease of maintenance, it is a method that shows considerable improvements and advances. That is, a conductive roller capable of applying a bias voltage is arranged close to the photosensitive drum having an electrostatic latent image, and the developing solution is supplied to the approaching portion while rotating in opposite directions. It is a method of developing. Then, it is considered that a plurality of blades are attached to and separated from each other around the conductive roller so that the toner remaining on the surface of the roller after development is scraped by this and collected in each color developer container. .. In this way, the cleaned roller surface after scraping the remaining toner
Upon approaching the surface of the photoconductor, the developer of the next color is supplied in the vicinity of the gap between them to develop and visualize the electrostatic latent image for the next color on the surface of the photoconductor.

However, even in this method, which is a great improvement over the conventional method, there are the following drawbacks. It is seemingly rational to develop each color with one roller, but each scraping blade for scraping each color developer must be arranged around the roller. The diameter of the roller becomes large, which hinders downsizing and simplification of the machine. or,
Due to the difficulty of completely scraping and developer spillage from the end of the roller, color mixing occurs during continuous use, and the dirty developer that is collected eventually leads to a clean developer for replenishment. Will be polluted.
Further, since each color developing solution has different proper developing conditions, it is necessary to adjust the developing gap for each color or the roller moving speed. Difficult

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the wet development method, particularly the problems in the improved technique described below, and also in continuous development. Another object of the present invention is to provide a liquid developing method characterized in that it is small in size, has a simple structure, and enables high-speed development without causing color turbidity.

[0007]

That is, according to the present invention, a rotating electrostatic latent image carrier can be moved in the developing unit in the opposite direction to the electrostatic latent image carrier and a bias voltage can be applied. It is characterized in that any one of a plurality of developing rollers thus formed is brought close to each other to form the developing section, and a predetermined color developing solution is supplied in the vicinity of the developing section. The present invention relates to a developing method using a color developing solution.

To facilitate understanding, the present invention will be described with reference to specific examples. A developing unit mainly composed of a conductive roller (hereinafter referred to as "developing roller") capable of applying a bias voltage is fixed to a plurality of necessary colors only on a radial armrest that is rotatably supported by a rotary arm. It is mounted so as to be kept at the position, and one of them is brought close to the surface of the photoconductive photosensitive drum as an image carrier and stopped, and is rotated in the direction opposite to the moving direction of the photosensitive drum. The rollers may be rotated and placed in advance.

Then, a liquid developer of a predetermined color is made to flow down through the gap between the two to develop the electrostatic latent image on the photosensitive drum. At this time, the liquid developer does not accumulate a required amount between the photoconductor drum and the developing roller and does not drip from the gap, and the distance between the gap and the circumference of the roller is adjusted so that the developing conditions are optimized. Adjust speed.
At the time of this development, a bias voltage is applied to the roller between the roller and the photosensitive drum to prevent unnecessary toner from adhering to the non-image area, and to make the toner uniform so that the edge effect does not occur. The development density is adjusted so as to promote proper adhesion and maintain the required color balance. When the development of one color is completed in this way, the developing roller is moved away from the photosensitive drum by rotating the arm, and another developing roller is brought to the surface of the photosensitive drum and stopped.

In the meantime, the previously formed color image on the surface of the photoconductor drum is transferred onto the paper surface, and after cleaning the photoconductor surface, it is charged and exposed to a light image of the next color, so that the color image is formed. A matched electrostatic latent image is created. After that, the development is performed in the same manner as before. A color image is thus created on the paper which is the image support by the subtractive three primary color toner and the black toner.

On the other hand, the developing roller, which has completed development, is rotated away from the photosensitive drum, and while being rotated, the toner is scraped off and cleaned by the scraping blade that comes into contact with the surface of the developing roller. The toner scraped off is collected in the toner container for supply.

In this way, since the developing roller is provided for each color, the above-mentioned color mixture does not occur, the initial color can always be maintained, and cleaning of the roller surface is not necessary. Even if it is necessary to change the developing gap and the rotation speed of the developing roller because the characteristics of the developer are different for each color, it is easy to take such means.

It should be noted that the above description has been made in order to facilitate understanding of the main points of the present invention, and these developing rollers need to be attached to a radial arm tree that is rotatably supported. However, the necessary developing rollers may be arranged at predetermined positions by arranging them in a line vertically or horizontally or by disposing a plurality of developing rollers around the photoconductor.

The developing roller does not need to be a cylindrical roller as in the present description, but may be a conductive belt suspended between two rollers, which is closer to the surface of the photoconductor. Since it can take a wide range, it is effective when the development efficiency is improved together with the downsizing. However, the present invention is not limited to such a specific arrangement structure, and various configurations that can achieve the object of the present invention are conceivable.

[0015]

【Example】

First Embodiment Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows the mechanism of a liquid color printer of the A4 size having a printing speed of 10 prints per minute, which employs the technique of the present invention.

Reference numeral 1 is a photosensitive drum, which has a surface speed of about 300.
With rotation in the direction of the arrow in millimeters, its surface is charged to about 600 volts by the corona charger 2.
Next, the laser scanner 3 writes with an optical image expressing an image color-separated by a blue filter to form an electrostatic latent image on the surface of the photoconductor. Reference numeral 4 denotes a developing unit according to the present invention, in which an arm member 6 having four developing rollers 5 attached to its tip is rotated around a central portion 7 so as to rotate any developing roller. It is designed so that it can be stopped by approaching it by 0.5 mm.

In the figure, one developing roller is stopped close to the surface of the photosensitive member, and the developing roller is opposite to the surface of the photosensitive member.
While rotating in the direction indicated by the arrow at a speed about three times the speed of the surface of the photoconductor, the yellow liquid developing solution is caused to flow out from the fixed developing solution supply portion 8 into this gap, and The electrostatic latent image on the surface is developed and visualized. At this time, a bias voltage is applied to the developing roller to prevent toner adhesion to the image background portion as much as possible.

After the development, the photosensitive drum is brought into contact with the transfer drum 10 having a transfer paper held on the surface thereof at the transfer portion 9 to transfer a yellow toner image of the photosensitive member to the transfer corona 11.
Is electrostatically transferred to the paper surface.

The roller 12 is for facilitating the transfer of the toner image on the photosensitive member before the transfer, and removes the toner in the background portion as much as possible and exists together with the toner.
It is for removing the insulating dispersion medium Isopar to the required limit.

After the transfer, the cleaning drum 13 removes the transfer residual toner in the cleaning section 13, and then enters the next cycle. That is, after charging, an electrostatic latent image is created by a light image of the next color that has been color-separated by a green filter from a laser scanner.

In the developing unit 4, the arm 6 is rotated until the electrostatic latent image reaches here, the preceding developing roller is removed from the surface of the photosensitive drum, and the developing roller for magenta is The surface of the photoconductor is stopped by approaching it, and the surface of the photoconductor drum is rotated in the opposite direction so that a bias voltage suitable for the next development can be applied. At this time, each developing roller always maintains its posture even if it rotates together with the arm as shown in the drawing.

When the electrostatic latent image on the photosensitive drum moves to the developing section thus prepared, the magenta developing solution flows out from the developing solution supply section 8 in synchronization therewith. Then, the gap between the photoconductor drum and the developing roller is filled and the development is performed. After the development, the photosensitive drum having the magenta image reaches the transfer portion through the pre-transfer image adjusting roller 12 and is transferred onto the transfer paper having the yellow image on the transfer drum 10 by the transfer corona as before. Transcribed. Continue these operations with cyan and black,
After the color image is created on the transfer paper, the transfer paper is discharged from the machine away from the transfer drum, and the color creation work is completed.

On the other hand, the developing roller scrapes off the developer remaining on the surface thereof by the scraping member 14 to keep the surface always clean, and the scraped developer is supplied to the developing solution supply container. Collect in 15 and reuse.

Since the developing roller is prepared for each color in this manner, even if the residual toner on the roller surface is not sufficiently scraped off or liquid spills from both ends of the roller, it does not matter. There is no concern about color turbidity in the operation, and in collecting the residual developer from the roller surface into the developer container, there is no color turbidity even after continuous printing. A print was obtained.
In addition, since each developing roller does not have a developing solution supply unit, even when the roller moves at high speed, the complexity of the solution supply mechanism and the solution spill measures are not required, and the size of the apparatus can be reduced. Together with the simple mechanism, it is easy to handle and requires no maintenance.

Embodiment 2 FIG. 2 shows another specific example of the developing method according to the present invention in a liquid-type color printer, as in Embodiment 1. The reference numerals used in the figure are the same as those in the first figure.

The photosensitive drum 1 rotates in the direction of the arrow at a peripheral speed of about 400 millimeters, is charged to a surface potential of about 700 V by a corona charger, and then the LED.
The array 16 exposes in a color-separated image to form an electrostatic latent image. Next, it reaches the developing unit 4 composed of four developing rollers arranged around the photosensitive drum, and one selected developing roller is rotated in the direction opposite to the drum surface at a surface speed about three times that of the developing roller. At the same time, they are brought close to the drum surface, and at the same time, a developing solution of a color complementary to the filter at the time of color separation is ejected from the developing solution supply section 8 to develop the latent image. At the time of this development, an appropriate bias voltage is applied to the developing roller to prevent unnecessary adhesion of toner to the background portion.

Along with the rotation of the photosensitive drum, the toner image on the surface is transferred by the roller 12 after removing unnecessary toner in the background portion and removing excess dispersion medium to adjust transfer conditions. The electrostatic charge is transferred by the corona charger 11 onto the intermediate transfer belt 17 made of a Kapton film (polyimide amide resin manufactured by DuPont) having a thickness of about 100 μm and having an LTV type silicone resin layer on the surface. The photosensitive drum that has passed the transfer portion reaches the cleaning portion, and the toner image remaining after the transfer is cleaned, and one cycle is completed. This kind of process, yellow, magenta, cyan,
By repeating the process for the four black colors, the desired color image is reproduced on the transfer belt. Finally, the toner image on the intermediate transfer belt is brought into contact with the transfer paper that moves in synchronization with the rotation of the belt, and is heated and softened by the action of the heater 18 from the back of the belt so that the toner image is formed on the paper surface. It is transferred and fixed on.

In this embodiment, four developing rollers are arranged around the photosensitive drum, so that there is an advantage that development can be switched more quickly than in the first embodiment. Here, the developing roller may have a structure in which a conductive belt is hung on three rollers, and the size of the structure can be reduced and the developing electrode area can be increased to enhance the developing electrode effect. Since the developer flowing on the developing roller is not brought to the further downstream side from the gap with the surface of the photoconductor by the rotation of the developing roller, the developing roller is arranged at an arbitrary position around the photoconductor drum. It is possible to do this, which also contributes to downsizing of the entire device. Further, by providing the developing solution supply section for each developing roller, the developing solution can be supplied more evenly than in the first embodiment,
It has been found to be suitable for high speed development. Furthermore, even though it is rotated at high speed due to the miniaturization,
The liquid did not scatter, and the problem of color turbidity did not occur even in continuous operation. In addition, each developing roller,
Similar to the first embodiment, a scraping member for scraping the residual developer is provided, the surface is cleaned, and the developer is collected in the developer source container.

[0029]

According to the present invention, it is possible to solve the problem of color turbidity when continuously producing prints, which has been a problem in the conventional liquid color printer, and is compact and easy to maintain. It is possible to develop a simple, reliable, high-speed printer, which increases the degree of freedom in design, which in turn leads to cost reduction.

[0030]

[Brief description of drawings]

FIG. 1 is an explanatory view showing a mechanism of an electrophotographic color printer showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing a mechanism of a mechanism of an electrophotographic color printer showing another embodiment of the present invention.

[Explanation of symbols]

 1 Photoreceptor Drum 2 Corona Charger 3 Laser Scanner 4 Developing Section 5 Developing Roller 6 Developing Arm Holding Arm 7 Arm Arm Rotating Shaft Support 8 Developer Supply Section 9 Transfer Section 10 Transfer Drum 11 Transfer Corona Charger 12 Pre-transfer Toner Image adjustment roller 13 Cleaning section 14 Residual toner writing-off member on developing roller 15 Developer supply container 16 LED array exposure section 17 Intermediate transfer belt 18 Heater for softening toner image on intermediate transfer belt

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Shigekazu Kitamura 2-33 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd. (72) Toshio Waku, 2-3-3 Kyobashi, Chuo-ku, Tokyo No. Toyo Inki Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. Any of a plurality of developing rollers adapted to move to a rotating electrostatic latent image carrier in the developing section in a direction opposite to the electrostatic latent image carrier and to apply a bias voltage to the rotating electrostatic latent image carrier. And a predetermined color developing solution is supplied in the vicinity of the developing section, and a predetermined color developing solution is supplied to the developing section.