JPH02106367A - Color printer - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention belongs to the field of wet color recording technology, and particularly relates to a color printer that records high-resolution color images with rich gradation on plain paper. .

(Prior art) Conventional electrophotographic technology is often practiced using a so-called dry method that uses powder toner, but powder toner consists of toner particles that are about 10 to 100 times larger in diameter than liquid toner, and the density of the image is different. The dither method using multiple dots is used to express the ion flow, so it has poor gradation and low resolution, so it is not suitable for printing images such as photographs.In contrast, controlling the ion flow In the wet development method, in which a latent image is formed using a liquid toner, the density can be specified for each dot to be written, so an image with high resolution and excellent gradation can be obtained.

However, in the conventional wet development method, toner with a negative charge is extremely difficult to manufacture, which is particularly noticeable in the case of color, so toners with a positive charge are generally used. On the other hand, in corona discharge, there is a situation in which positive ions are more stably generated than negative ions in a more uniform amount throughout the generating body. Therefore, there was a problem in that it was difficult to match the polarity of the latent image and the toner. Furthermore, the wet type development method has the problem that excess toner liquid adheres to the latent image carrier during development, and if this is transferred directly to paper, background stains are likely to occur.

A method of controlling ions generated by a charger as an ion stream using an electrode pair will be described below.

FIG. 7 shows an example of an electrode pair 31 for controlling the ion flow, in which 31a and 31b are control electrodes, 31C is an insulating separation layer, and 31d is a small-diameter opening, in which a large number of openings are provided. There is.

FIGS. 8(a) and 8(b) are diagrams illustrating the operation of the write charger 3 using the electrode pair 31 of FIG. 7. Figure 8(a), (
In b), 1 is a latent image carrier, 32 is a shield electrode,
33 is a wire electrode, 34 is a counter electrode, 35 is a power source, 36
is a power source that applies a high voltage between the control type 131b and the counter electrode 34. As shown in FIG. 8(a), when a positive voltage is applied by the power supply 35 to the control electrode 31a near the wire electrode 33, the positive ion flow generated near the wire electrode 33 passes through the opening 31d. Then, the latent image carrier 1 is reached. Conversely, as shown in FIG. 8(b), when a negative voltage is applied, the ion flow is blocked from passing through. Therefore, the amount of passage can be controlled by the value of the applied voltage.

[Problem to be solved by the invention]

With conventional dry methods, it has been impossible to record images with high resolution and high gradation due to the particle size of the toner.

Also, as mentioned above, even in the wet method, since the toner has a positive charge, it is necessary to form a latent image with a negative charge.
There was a problem in that it was difficult to generate uniform negative ions. Furthermore, in the conventional developing method, liquid toner adheres to the latent image carrier 1, which tends to cause deterioration in recording quality.

An object of the present invention is to provide a small and inexpensive color printer that records high-quality color images with high resolution and rich gradation on plain paper using a wet development method using liquid toner.

[Means to solve the problem]

A color printer according to the present invention includes a band-shaped flexible latent image carrier and a grid electrode on the front surface for each color to be recorded, and uniformly charges the latent image carrier with negative ions. A charger, a write charger that has a pair of electrodes for controlling ion flow with a large number of small-diameter openings on the front surface and controls the ion flow, a developer that uses liquid toner after the write charger, and a developer for each color. After all development is completed, the toner image is transferred to a sheet of paper.

Furthermore, a squeeze charger that generates positive or negative ions for each color to be recorded may be provided at a stage further downstream of the developing device subsequent to the write charger.

[Effect]

In this invention, for each color to be recorded, negative ions are uniformly irradiated onto the latent image carrier using a negative line charger, and then image inversion information is written using positive ions using a writing charger. Form a latent image. Next, after development is performed with a positive toner liquid, the developed image (toner) on the latent image carrier is transferred to paper by a transfer charger.

In addition, excess toner liquid that adheres to the latent image carrier during development is
It is pushed back toward the developing device by a squeeze charger installed after the developing device.

(Example) FIG. 1 shows a schematic diagram of the configuration of an ion flow recording type color printer according to the present invention. 1 is a latent image carrier; 2 is a uniform charger that uniformly charges the entire area of the latent image carrier 1 to a predetermined potential; 3 is a writing charger that writes a latent image of an image; 4 5 is a developing device, 5 is a transfer charger, 6 is a cleaning section, 7 is a fixing and drying section, and 8 is the latent image carrier 1.
9 is a guide roller of the latent image carrier 1;
10 is paper, 11 is a paper feed roller, 12 is a paper feed roller, 13 is a paper guide, and 14 and 15 are paper trays.

I, II, III, IV are G, B, R.

Each stage uses toner liquid for each color of BK, and each stage uses a - line charger 2. Writing charger 3. It consists of a developing device 4.

FIG. 2 shows an example of the structure of the latent image carrier 1. As shown in FIG. Reference numeral 1a denotes a dielectric layer, which is made of, for example, PET and has a thickness of 0.1 μm to 3 μm. 1b is grounded with a conductor layer, which is made of a vapor-deposited aluminum film, for example, and has a surface resistance of 100Ω to IOMΩ.
shall be. 1C is a base layer provided to hold the two layers and endure transportation, and is formed of, for example, a PET film of 25 μm to 150 μm. The entire structure is formed into a loop-like flexible band.

Figure 3 shows uniform charger 2. Writing charger 3 and developer 4
, 21 is a shield electrode of the negative line charger 2, 22 is a wire electrode, and 23 is a grid electrode provided so that charging by the charger 2 is uniform. The structure of the write charger 3 is as shown in FIGS. 8(a) and 8(b). 41 is a toner tank of the developing device 4;
2 is a liquid toner, 43 is a developing roller, and 44 is a squeeze roller. These are provided as many times as there are colors for recording multiple colors.

Next, the operation will be explained.

First, the latent image carrier 1 is uniformly charged with negative ions using the negative line charger 2 . Next, writing is performed by controlling the ions generated by the writing charger 3 as an ion flow using the electrode pair 31. That is, as shown in FIG. 8(a) described above, when a positive voltage is applied to the control electrode 31a near the wire electrode 33, the positive ion flow passes through the opening 31d and reaches the latent image carrier 1. reach. Conversely, as shown in FIG. 8(b), when a negative voltage is applied, the ion flow is blocked from passing through. Therefore, the amount of passage can be controlled by voltage. In this way, inverted image information is sequentially written on the latent image carrier 1 (positive ions are not irradiated where toner should be placed, but positive ions are irradiated where toner should not be placed). By doing this, the positive charges that are superimposed on the negative polarity charges on the latent image carrier 1 are neutralized, and negative charges remain where the positive charges are not absorbed, and as a result, the latent image carrier 1 1, image information (not inverted information) is formed as a latent image by negative charges. next,
When the latent image on the latent image carrier 1 is further fed and reaches the developing device 4, the positive polarity liquid toner pulled up from the toner tank 41 by the developing roller 43 adheres to the latent image carrier 1, and the charge is removed. Toner is attracted to a certain portion, and the latent image is developed, that is, made visible. At this time, the excess toner liquid adhering to the latent image carrier 1 is removed by the squeeze roller 44.

Here, the effect of equalizing the charging of the grid electrode 23 of the - line charger 2 will be described. Corona voltage -7 kV, distance t between grid electrode 23 and latent image carrier 1, smm, grid hole diameter 400 μm, opening density per grid 402 pieces/c
When a charging experiment was carried out with a grid electrode 23, the results shown in Fig. 6 were obtained.
Curve (b) is the case without the grid electrode 23, and it can be seen from this figure that the surface potential is made uniform by the grid electrode 23. If a positive toner liquid 42 is applied to the latent image obtained using this negative line charger 2 in the next developing unit 4, the latent image is simply created using negative ions without using this negative line charger 2. An image with better quality can be obtained compared to the case where the image is formed. Further, although the conventional liquid toner 42, particularly in the case of color, has not been commercially available with a negative charge, the above-described structure has the advantage that it can be used.

Referring again to FIG. 1, when development is completed for each color to be recorded, the toner image on the latent image carrier 1 is transferred onto the paper 10 by the transfer charger 5. In this process, paper 10
are sent out one by one to the transportation route of the paper 10 by the paper feed roller 11, and moved along the paper guide 13 by the paper feed roller 12, so that the image on the latent image carrier 1 comes to the charger 5 for transfer. It is sent at the same speed with the same timing. The paper 10 on which the image has been transferred is heated in the fixing/drying section 7. Then, the toner is fixed on the paper 10, the toner solvent liquid evaporates, and the paper 10 is dried and enters the paper tray 15.

FIG. 4 shows an example of the configuration of another embodiment of the color printer according to the present invention. Reference numeral 16 in FIG. 4 is a squeeze charger, which is provided for the purpose of removing excess toner liquid 42 adhering to the latent image carrier 1 during development. This is because when writing the next color information, the latent image carrier 1 is uniformly charged negatively, but it is better to perform this process after charging it positively in the previous step, rather than charging it to the same negative polarity. It is possible to remove uneven charge distribution caused by friction, etc., to obtain a uniformly charged state with good uniformity, and because the toner has positive polarity, it is easy to transfer during transfer.

Since the latent image carrier 1 is tilted by the guide roller 9, excess toner liquid is squeezed into the charger 1.
The excess toner liquid is easily returned to the toner tank 41 due to the repulsion of the ions generated by the toner liquid 6 and the weight of the excess toner liquid. This effect is
The distance from the closest point between the developing roller 43 and the latent image carrier 1 to the wire electrode 16a of the squeeze charger 16 is 50a+
Appears at a diameter of 10 to 15 mm. Further, when the distance is 10 to 15 mm, the inclination angle θ is effective when θ≧0, and the effect is large when θ≧30°. The above distance is 20~5
At 0 mm, the effect is effective when θ≧O, and when θ≧45°, the effect is large. Such a structure is made possible by the flexible belt-shaped latent image carrier 1, and this also makes it possible to This also contributes to miniaturization. In this embodiment, other operations are the same as in the embodiment of FIG.

FIG. 5 shows another example of the configuration of a color printer according to the present invention. The difference from the embodiment shown in FIG. 4 is that a uniform charger 2 is also used instead of the squeeze charger 16, which has the advantage of simplifying the configuration and making the device smaller. Since the ions used for this purpose have negative polarity, the quality of the image is slightly degraded as described above.

〔Effect of the invention〕

As explained above, this invention has a flexible belt-shaped latent image carrier and a uniform charger that has a grid electrode on the front surface and uniformly charges the latent image carrier with negative ions. , a writing charger that has a pair of electrodes for controlling ion flow with a large number of small-diameter openings on the front surface and controls positive ions by an electric field in the openings, and a developing device that uses toner liquid containing positive toner. Since it is equipped with a transfer charger that performs transfer using negative ions, it is possible to create a color printer that can record high-quality color images with high resolution and rich gradation on plain paper using conventional toner liquid. Can be configured.

Furthermore, since a squeeze charger is provided after the developing section, not only can excess toner liquid be easily removed, but also a compact color printer with extremely good images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the configuration of an embodiment of an ion flow recording type color printer according to the present invention, FIG. 2 is a diagram showing an example of the structure of a latent image carrier used in the present invention, and FIG. 3 is a diagram showing a uniform charger,
FIG. 4 is a schematic diagram showing the structure of another embodiment of the present invention; FIG. 5 is a schematic diagram of the structure of still another embodiment of the invention; FIG. 6 is a diagram showing the grid structure. A surface potential distribution diagram showing the effect of the electrodes. Figure 7 is a perspective view of the main part explaining the structure of the electrode pair for controlling ion flow. Figures 8 (a) and (b) are the electrodes in Figure 7. FIG. 3 is an explanatory diagram of the operation of a write charger configured using a pair. In the figure, 1 is a latent image carrier, 2 is a uniform charger, 3 is a writing charger, 4 is a developer, 5 is a transfer charger, 6 is a cleaning section, 7 is a fixing/drying section, 8 is a feed roller, 9 is a guide roller, 10 is paper, 11 is a paper feed roller, 12 is a paper feed roller, 13 is a paper guide, 14.15 is a paper tray 1
6 is a squeeze charger. ] Figure Figure Figure 4 Figure Figure Figure Figure

Claims (2)

[Claims] (1) In a color printer that develops an electrostatic latent image for each color with liquid toner and then transfers and fixes it onto plain paper, a flexible belt-shaped latent image carrier and a front panel for each color to be recorded are used. a uniform charger having a grid electrode and uniformly charging the entire surface of the latent image carrier to a predetermined negative potential with negative ions; and a uniform charger having a pair of electrodes having a large number of small-diameter openings on the front surface to charge positive ions. a writing charger whose current is controlled by an electric field in the opening; a wet type developer which develops the electrostatic latent image with a toner liquid containing positive toner; and a toner image formed in each color on a sheet of paper. A color printer comprising a transfer charger that generates negative ions for transfer. (2) The color printer according to claim 1, further comprising a squeeze charger that generates positive or negative ions after the developing unit for each color to be recorded.