JPS58166364A - Three color printer - Google Patents

Abstract

PURPOSE:To obtain exposure with high resolution and high accuracy and a three color printer having a small size, high performance, etc. by using laser scanning light for image exposure, and performing the stages including one time of image exposure, two times of development and one time of full surface exposure. CONSTITUTION:Photoreceptors 10, 41 are constituted of a conductive substrate 11, a photoconductive layer 12 and a transparent insulation layer 13. The photoreceptors are subjected to primary electrification with a unit 42 for simultaneous primary electrification and full surface exposure, and to electrification to an opposite polarity with a charger 43 for secondary electrification, so that the latent images of the 1st-4th potential levels corresponding to three colors and a white part are formed by one time of image exposure. The 1st, the 2nd potential levels are developed with the toner of the 1st color in the 1st development 46. Following thereto, the photoreceptors are subjected to full surface exposure, and then the 2nd and the 3rd potential levels are developed with the toner of the 2nd color in the 2nd development 48. The 2nd level is formed with the mixed color of the toner of the 1st color and the toner of the 2nd color.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] Wood climbing If! relates to a three-color printer that is a non-impact printer using a photographic technology and is suitable for computer output, office output terminals, and the like.

[Prior art and its problems]

Conventionally, there is a laser beam printer as a stone device that prints information using electrophotographic technology. In addition to the demand for high-speed, large-volume printing to meet the increasing amount of data processing, this requires
There was a demand for an easy-to-understand output format that made full use of kanji, kana, etc., and it was developed and put into practical use as one of the solutions.

However, this method does not support output formats in which salaries are recorded in the same color and are easy to understand, but in a color-coded format. On the other hand, the appearance of a printer that can print front pages in this way is particularly desirable for document office work where the printers are color-coded in different colors for easy understanding.

Printers using electrophotography create an electrostatic latent image using electrical charges and optical information, develop this static latent image, and then transfer this developed image to transfer paper. To obtain a three-color print, the above method is used. First color information obtained on transfer paper by electrophotography
A developed image of the second color information obtained using the electrophotographic method was superimposed on the iusa, and then a developed image of the third color information was superimposed and transferred in the same way.The same photographic method was applied three times. It was a recurring thing.

Further, an electrostatic image is formed on the photoreceptor by exposure of the 10th color information, and a fill image is formed, an electrostatic IIF image is formed by exposure of the second color information, and a second fill image is formed, and the third color information is exposed. It is also conceivable to form an electrostatic snow image by forming an electrostatic snow image, and to form a three-color visible image on a photoreceptor by a third process, and then transfer the image.

However, these devices generally have drawbacks such as complex structure, large size, and high cost.

[Purpose of the invention]

The present invention was developed in consideration of the above-mentioned circumstances, and its purpose is to provide a three-color printer that is compact, has high performance, and is capable of printing in three colors.

Here, three-color printing is defined as follows. + In other words, three-color printing means printing the first, second, and third colors of three different colors on a white background.
An image printed as information. However, the white color of the background part is not limited to pure white, and may be as strong as white.In the following, among the colors of the image that constitutes the information, the first color is C11, the second color is C2, and the third color is C2. is written as C3.

The present invention uses a three-layer photoreceptor for primary and secondary charging, image exposure,
Visible images of three colors are obtained through five steps: first development, full exposure, and second development.

First, the polarity is opposite to the primary charging/full exposure and the primary charging.
Next, perform charging. Next, one image exposure forms charge potentials of four potential levels including the background part, and in the first current potential level, a first potential level L1 corresponding to color C1 and a color C2 are formed.
A second potential level L2 corresponding to color C1K is developed with toner T1 corresponding to color C1K. The developing conditions at this time are the first and second development conditions.
The developing bias is set to the second and third positions so that only the charge latent potential of the potential levels Ll and L2 is developed.
Set between.

Furthermore, the entire surface is exposed to light to form a potential latent image at a third potential level corresponding to the color C3, a fourth potential level L4 corresponding to the background area, and a second potential level L2 again corresponding to the color C2. Then, in the second display, 1 is used for toner T2 corresponding to color C3.
Second potential level l172 corresponding to color C2 and color C3K
A charge layer image at a corresponding third potential level L3 is developed.

The developing conditions at this time are the 10th potential level L after the entire surface is lightless.
1 and the second potential level L2.

In this series of steps, the first potential level L1 corresponding to color CIK is toner Tl, the second potential level L2 corresponding to one color 02 is toner Tl and toner T2, and the third potential level corresponding to color 03 is L3 is developed with toner T2. In other words, the second potential level L2 corresponding to the color C2 realizes the third color as a mixture of the toner TI and the toner T2.

〔Effect of the invention〕

As described above, according to the present invention, the process can be significantly simplified compared to the conventional method, which requires one image exposure, two development steps, and one full-surface exposure. By using scanning light, high-resolution and high-precision image exposure is possible, and a compact, high-performance, low-cost three-color printer can be realized.

L Examples of the Invention] - The present invention will be described in detail below with reference to the drawings. FIG. 1 shows the structure of a photoreceptor used in the practice of the present invention. Photoreceptor (111 is 8e on a conductive substrate (b) made of aluminum etc.
It has a three-layer structure in which a photoconductive layer (2) such as -Te is provided, and a transparent insulating layer such as Lumirror (trade name of polyethylene terephthalate) is provided on this photoconductive layer (2). The photoconductive layer (2) shall have appropriate spectral sensitivity including the wavelength of the light source used for exposure.

A three-color electrophotographic process according to the present invention is shown in FIG. 2r. First, in the first step, as shown in Figure 2 (1) K, the trap photoreceptor (
1 While exposing the whole duck to light, it is charged with a predetermined polarity K (negative polarity in the example #) using a charger (2).

This charging process is called primary charging. The photoconductive layer (6) becomes conductive due to the irradiated light, and charges with a polarity anisotropic to the polarity of the charger (positive polarity in this example) are transferred to the photoconductive layer (6).
b) and the transparent insulating layer (2).

Next, the surface of the photoconductor (I) that has been primarily charged in this way is subjected to secondary charging in the dark with a polarity opposite to the primary charge.The degree of this charging is determined by The polarity of the surface potential is reversed from negative to positive while leaving a negative charge due to the primary charging.In other words, since the secondary charging is performed in the dark, the photoconductive layer (2) and the transparent insulating layer (
2) The distribution of positive charges distributed at the boundary between the
The positive charge mentioned above has a predominant influence on the surface potential of the photoreceptor.
vinegar.

The above surface potential is inverted.

Next, as shown in FIG. 2 (3), the colors C1 and C2 are
, C3 and four pieces of information corresponding to the background area are applied to the photoreceptor surface while changing the exposure amount, and four different potential levels Ll, L! , L3. Start making L4.

This is called great exposure.

In this state, the current charge value V of the positively charged toner T1 is
DI is between potential levels L2 and L3, and potential levels L3 and L4, which are more positive than VDI, are not developed, but toner T1 adheres to potential levels L1 and L2, which are negative, and are developed. At this time, more toner adheres to potential level L1, which has a larger potential difference, than to L2. This is called the first current salary.

Furthermore, the entire surface of the photoreceptor is made dark with an amount of light such that the potential level L4 corresponding to the background portion becomes near zero potential and the potential level L3 corresponding to the color C3 becomes negative. This is called full exposure and is shown in FIG. 2(5)K.

FIG. 2(6)K shows how development is performed in this state using the positively charged toner T2. The current bias VD at this time is set between potential levels L1 and L2, and potential levels L1 and L4 that are more positive than VD2 are not developed, but toner T2 adheres to potential levels L2 and L3 that are negative. At this time, more toner adheres to the potential level L3, which has a larger potential difference.This is called the second developer.As can be seen from FIG. 2 (6), the color C2 is The corresponding potential level L2 is the color CIK and the corresponding toner T1 and color C3.
The color mixture of toner T2 corresponding to C2 becomes the color C2, and the amount of adhered toner can be made uniform for each color.

Further, regarding the color C2, it is possible to change the color by changing the ratio of the amount of adhered toner during the first development and the second development, which is one of the features of the present invention.

This completes the development of Kureiden**, which supports three colors. FIG. 3 shows potential changes on the surface of the photoreceptor during this series of steps.

One of the major features of the present invention is that it realizes an electrophotographic process in which visible images corresponding to three colors can be obtained using one regression exposure, one grid exposure, two development steps, and two color toners. It is one. The three visible colors thus obtained are transferred onto a recording sheet in the next transfer process and then fixed.

FIG. 4 shows an example of a three-color printer for carrying out the present invention.
This is a series of books that covers the charging, exposure, and development processes shown in the figure, as well as transfer, snow removal, and cleaning.

Around the photosensitive drum I, there is a counterclockwise direction [? From the top, there are q primary charging/simultaneous exposure units, q secondary charging chargers, and my exposure unit (including the scanning optical system).
machine, 1st current unit (4e1 full-scale exposure unit (4η
, a second current transfer unit-1 transfer paper guide (4 transfer charger, static elimination unit 61) and a cleaning brush 5 are arranged, respectively.

The scanning optical system (Incorporated) in the imageless unit (c) uses a laser beam to scan the surface of the photosensitive drum G41) in a line (in the direction perpendicular to the plane of the paper in Fig. 4). I perform my exposure in conjunction with the rotation of . The exposure amount is determined by periodically modulating the intensity of the laser beam according to the color information of the three colors and the background area. Bottle 44-1 is a reflecting mirror.

The developed visible images of the three colors on the photosensitive drum are transferred to transfer paper from a transfer charger (to) k. After the photosensitive drum has been transferred, the remaining toner is removed by the cleaning brush 6'JK after the static electricity is removed by the static eliminating unit 6υ, and the drum is used again.

As described above, according to the present invention, it is possible to provide a three-color printer with a simpler configuration, smaller size, and higher performance than the conventional example.

[Other embodiments of the invention]

It goes without saying that the present invention can be implemented with various modifications other than the above embodiments etc. For example, the polarity of primary charging, secondary charging, and charging polarity of toner are not necessarily limited to the combinations of the above embodiments. The effectiveness is the same even when the polarity is reversed. The trench exposure is not limited to a laser scanning system, and any other light scanning optical system such as an LID array may be used.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the structure of the photoreceptor used in the present invention, Figure 2 is a diagram explaining the principle of the present invention as a model, and Figure 3 is the surface potential in the series of steps shown in Figure 2. 811% representing the change in 4111 is a schematic diagram for explaining the embodiment. 41...Photosensitive drum 42...Primary charging/simultaneous exposure unit 43...
Secondary electrification charger 45...my exposure unit 46
...First developing unit 47...Full surface exposure unit 48...Second developer unit 49...Transfer paper guide 50...Transfer charge-51...Static elimination unit 52 ...Cleaning Brush Representative Patent Attorney Kensuke Chika (and 1 other person),' Figure 1 Figure 2 Light Figure 2 (Government Figure 3 ■

Claims (2)

[Claims] (1) In the electrophotographic process that forms a three-color image,
Using a three-layer photoconductor consisting of a conductive substrate, a photoconductive layer, and a transparent insulating layer, primary charging and full-surface exposure are performed, secondary charging is performed with a polarity opposite to the primary charging, and O is applied once. The first image exposure corresponds to three colors and white 1sK. 2nd% 3rd, 4th
In the 11th AIII, a charge tank with a potential level of 1. The second potential level is developed with the first color toner, then the entire surface is developed, and the second and third potential levels are developed with the second color toner in the second development. A three-color printer having an electrophotographic process in which the second level is formed by a mixture of a first color toner and a second color toner as a 41I image. (2) A three-color printer according to claim 1, characterized in that the secondary exposure uses laser scanning light whose intensity is modulated in accordance with four types of color information.