JPH0374389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to an image forming method using a photoconductive toner, and more particularly to an electrophotographic copying method.

2. Prior Art Conventionally, there has been a desire to obtain copies of, for example, a multicolor original (original) in two or more colors. For example, in a document to be copied, characters, lines, etc. are usually expressed in black, and it is common practice to express parts particularly in red or underline them in red.
However, even if this is copied using a normal electrophotographic copying device, the red portion will be expressed almost identically to the black portion, and the distinction by color coding cannot be reproduced. Conventionally, the following electrophotographic method has been known as a copying method that meets these demands (see, for example, Japanese Patent Application Laid-Open No. 51-94935). In other words, a photoreceptor with panchromatic photosensitivity is image-exposed through a cyan filter, the areas corresponding to red and black are developed with red toner and transferred, and then image-exposed through a red filter to produce black. In this method, only the corresponding portions are developed with black toner, aligned, transferred, and fixed. This method can be implemented mainly using conventional black-and-white copying machine technology, but in order to perform color separation of the color image on the original, the photoreceptor is exposed at least twice to the color-separated original light image. , development must be repeated, and therefore, there are problems in that the time required to obtain one copy is long, the operation is troublesome, the structure is complicated and large, and the cost is also high.

Also, for example, JP-A-52-143834, 53-39750
In each publication, a method is disclosed in which three types of photoconductive toners, yellow, magenta, and cyan, are used to obtain full color by one exposure and development. However, this method requires three types of toners, and it is difficult to obtain them with uniform photosensitive characteristics, and variations in characteristics are likely to occur among the toners themselves or among the toners.

Moreover, in this conventional method of using three-color toner, a mixture of yellow, magenta, and cyan toner particles is used to produce black, but although this produces black, it gradually fades. Due to the lack of strength, it is necessary to reapply the toner mixture to the same area. In addition, since the black area is formed using three types of toner, the area of the black image area is expanded, which tends to lower the resolution.

3. OBJECT OF THE INVENTION An object of the present invention is to provide an image forming method that can form a clear color image quickly, accurately, and with a simple process.

4. Structure of the Invention That is, the present invention provides an image forming method using a photoconductive toner, including a first chromatic colored photoconductive toner that absorbs light in a specific wavelength range and becomes conductive; An image forming method that simultaneously uses a second black colored photoconductive toner that absorbs almost all of the light and becomes conductive, the first chromatic colored photoconductive toner and the second black colored photoconductive toner. a step of distributing a mixture with a photoconductive toner on a base electrode; a step of imagewise exposing the base electrode with a bias voltage applied between the base electrode and a counter electrode opposite thereto; The present invention relates to an image forming method characterized by including a step of causing toner particles that have absorbed light due to imagewise exposure to fly toward the counter electrode.

5 Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a case will be described in which an image is formed in two colors, red and black, on a white background as an example.

The photoconductive toner used in carrying out the copying method of this embodiment is a first chromatic colored photoconductive toner having absorbance in wavelength range 1 (approximately 400 to 600 nm) as shown in FIG. 1a. Particles (hereinafter referred to as A particles),
As shown in FIG. 2a, second black colored photoconductive particles (hereinafter referred to as B
They are called particles. ). Therefore, as shown in Figure 1b, the A particle has a wavelength of approximately 400 to 600 nm.
Absorbs chromatic light of approximately 600 to 700 nm wavelength 3
In addition, as shown in FIG. 2b, the B particles have the property of absorbing chromatic light in the entire visible range and becoming conductive. The image area made up of only A particles is red, the image area made up of only B particles is black, and the image area made up of A and B particles is almost black due to the covering effect of B particles. You will get it.

Next, the electrophotographic copying method of this embodiment will be explained with reference to FIG.

First, as shown in FIG. 3a, A particles 1 and B particles 2 are uniformly placed on the base electrode 5 (as a mixture).
Distribute it. This may be carried out under the influence of an air stream or an electric field.

Next, as shown in FIG. 3b, a document 6 consisting of a black image area 8, a red image area 9, and a colorless background area 11 is prepared.
A white light 12 is irradiated onto the substrate, and the transmitted light (or reflected light may also be used) 3 and 4 is sent to the opposite electrode 7 of the base electrode 5.
The substrate electrode 5 is irradiated through the beam. At this time, a DC voltage V is applied between the base electrode 5 and the counter electrode 7, the negative electrode side of which is connected to the counter electrode 7, and the base electrode 5
Apply voltage so that it becomes the positive electrode. The transmitted light (or reflected light) corresponds to each image part of the original 6, of which the A color light 3 corresponds to the red image part 9,
Both A-color and B-color lights 3 and 4 are obtained from the colorless background portion 11. A color light 3 is not absorbed by A particles 1 but is absorbed by B particles 2, while B color light 4 is absorbed by both A particles 1 and B particles 2. By this light irradiation, each particle on the base electrode 5 receives the incident light 3 or 3 and 4 and becomes selectively conductive, and is charged to the same polarity as the base electrode 5 (positive in this example). .

Then, these positively charged A particles 1 and B
As shown in FIG. 3c, the particles 2 fly while being electrostatically attracted to the opposite electrode 7 and are adsorbed onto the opposite electrode 7. This suction pattern exactly matches the image exposure pattern in Figure 3b, so
On the counter electrode 7, a red image consisting of A particles 1,
Black images are obtained from the A particles 1 and the B particles 2 as negative images on the original 6, respectively. On the other hand, a positive image with a pattern opposite to the negative image is left on the base electrode 5.

Next, as shown in FIG. 3d, the positive image on the base electrode 5 is subjected to full-surface exposure 12' while applying a DC voltage V' between the recording material 14 and the base electrode 5, and is exposed in the same manner as described above. The base electrode 5 is based on the principle of
The upper particles 1 and 2 are positively charged, flown toward the recording material 14, and adsorbed or transferred thereto. This transfer pattern is a positive pattern that accurately corresponds to the original image.

Next, as shown in FIG. 3e, the recording material 14 is passed through the fixing roll 15 to fix the image, and as shown schematically in FIG. 3f, a black image area 8', a red image area 9', and a white background area are formed. Final copy 1 consisting of 11'
Get 4. This fixing may be performed by a method using a solvent, pressure, etc., in addition to using the above-mentioned rolls.

As explained above, according to this embodiment, since the A particles of the photoconductive toner have the selectivity of absorbed light, there is no need to use a filter for color separation as in the past. A two-color image can be obtained with a single exposure, and the equipment used is also smaller.
Can be simplified. Moreover, since only two types of toner are used, it is possible to make copies that are of sufficient practical value, and also to eliminate variations in the photosensitive characteristics of the toners, making it possible to make copies with good reproducibility.

In addition, in the conventional method using three-color toner, a mixture of yellow, magenta, and cyan toner particles is used to produce black, but although this produces black, the degree of blackening is Because of the lack of toner mixture, it is necessary to reapply the toner mixture to the same area. In addition, since the black area is formed using three types of toner, the area of the black image area is expanded, which tends to lower the resolution. In contrast, in this embodiment, black can be produced using only two types of toner, and since one of them is black toner, the process of forming a black image area is easy, and the resolution and degree of blackening are large. improves. It has been confirmed that the degree of blackening is considerably improved compared to conventional methods.

In the above example, for example, in the step of FIG. 3b, light is irradiated through the counter electrode 7, so the counter electrode 7 needs to be transparent,
As shown in the figure, the base electrode 5 may be made transparent and light may be irradiated through this electrode. Furthermore, in order to prevent charges having the opposite polarity from the particles flying toward the counter electrode 7 from being injected from the counter electrode 7, an insulating layer 13 is provided on the counter electrode 7 as shown in FIG. is desirable. Furthermore, of the two types of photoconductive toner particles A and B used in the above example, it is only necessary that only one particle A has wavelength selectivity, so it is possible to use types of colored particles other than those mentioned above. . The charging polarity of the photoconductive toner described above may also be negative, which is opposite to that described above.

Next, an example of an apparatus for carrying out the above-described copying process will be described with reference to FIG.

In this device, a toner particle spreader 17, a moving film-shaped counter electrode 7, an exposure light source 16, a fixing roll 15 for a recording material 14, and a cleaning device 18 are arranged around a drum-shaped base electrode 5, respectively. . The original 6 is inserted between the exposure light source 16 and the electrodes 7 and 5 as shown. The counter electrode 7 is spanned between each roller 20 and is successively cleaned by a cleaning member 21. Recording material 1
4 is guided to the base electrode 5 side by the roller 22 and fixed by the roll 15 after being transferred. The exposure light source 23 during transfer is arranged at the position shown in the figure, but it may also be arranged at other positions (especially between the image exposure area and the transfer area) or inside the base electrode 5 as shown by the imaginary line. .

If you use a copying machine configured in this way,
It will be understood that each step shown in FIG. 3 can be performed with good reproducibility. In addition, in FIG. 6, the toner thickness regulating plate 2 is installed immediately after the toner particle sprayer 17.
4, it is possible to uniformly spread toner particles on the base electrode 5 in a state close to a single layer. Furthermore, if the toner particles on the counter electrode 7 after image exposure are transferred onto another recording material (not shown) without being removed by cleaning as described above, a negative pattern image can be obtained.

6 Effects of the Invention As described above, the present invention uses, as toner particles, a first toner that absorbs light in a specific wavelength range and a second toner that absorbs light in almost the entire visible range. A toner mixture is distributed on a base electrode, image exposure is performed on the base electrode while a bias voltage is applied between the base electrode and a counter electrode facing the base electrode, and the toner absorbs light from this image exposure. Since development is performed through the step of causing the particles to fly toward the counter electrode, an image consisting of a specific color and black can be easily obtained with one exposure. Moreover, since the covering effect of the second toner is sufficient, the degree of blackening and resolution of the black image area are greatly improved, and variations in the photosensitivity characteristics of the toner itself are sufficiently suppressed, resulting in good image quality. Obtainable.

[Brief explanation of drawings]

The drawings show examples of the present invention, and FIGS. 1a and 2a are diagrams showing the absorbance of two types of toner, and FIGS. 1b and 2b are diagrams showing the absorbance after absorption by the same toner. A diagram showing the light intensity of the light, Figure 3 a, b, c,
d, e, f are schematic flow diagrams showing the steps of each copying process, Figure 4 is a schematic diagram of other image exposure process stages, Figure 5 is a schematic diagram of other development process stages, and Figure 6 is an electronic FIG. 1 is a schematic cross-sectional view of main parts of a photocopying apparatus. In addition, in the symbols shown in the drawings, 1...A particle, 2...B particle, 3...A color light, 4...B color light, 5...substrate electrode, 6...original, 7...counter electrode, 8, 8'... Black image area, 9, 9'... Red image area, 11, 11'... White background area, 12, 1
2'...Light, 14...Recording material, 15...Fixing roll, 16, 23...Light source, 17...Toner particle sprayer, V, V'...Bias voltage.

Claims (1)

[Claims] 1 In an image forming method using a photoconductive toner, a first chromatic colored photoconductive toner that absorbs light in a specific wavelength range and becomes conductive; A method for forming an image in which a mixture of the first chromatic colored photoconductive toner and the second black colored photoconductive toner is used as a substrate. a step of distributing the toner particles on the electrode; a step of imagewise exposing the base electrode with a bias voltage applied between the base electrode and a counter electrode facing thereto; and toner particles that have absorbed the light resulting from the imagewise exposure. An image forming method characterized by comprising the step of causing the ink to fly toward the counter electrode.