JPS6031150A - Formation of color image - Google Patents

Abstract

PURPOSE:To obtain image elements with high sensitivity through exposure in only once by scattering magenta, yellow, and cyan photoconductive toners sensitive to red, green, and bule lights, respectively, on a substrate, electrostatically charging these toners, exposing them to erase the charge, and finally removing the remaining charge-erased toner particles. CONSTITUTION:Colored photoconductive toners each having a high sensitivity wavelength region and a colored absorption wavelength region not overlapping with each other are used, and they are exposed to converted lights corresponding to electric color image signals to form an image. Magenta, yellow, and cyan colored photoconductive toners sensitive to red, green, and bule lights, respectively, are uniformly scattered on a substrate, these 3 kinds of toners are charged and exposed to erase said charge selectively, and the charge-erased toner particles are removed from the substrate. Said photoconductive toners are formed by adding a photosensitizer and a colorant to a photoconductor, such as S, Se, or Zn compd, and further adding a binder resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image forming method using photoconductive toner, and particularly to a color image forming method capable of obtaining a color image with high sensitivity in one exposure.

Conventionally, various methods have been proposed for storing electrical color image signals and obtaining so-called hard copies so that they can be handled.

For example, inkjet printing and thermal dyeing methods are known, in which the coordinates corresponding to signals on recording paper are colored in accordance with image signals (for example, by spraying ink of a predetermined color or coloring thermal recording paper by heat). In this type of method, images are sequentially formed by mechanically scanning the coloring means along the coordinates on the recording paper, so it takes a lot of scanning time to obtain a precise image, and the coloring means There is also a limit to the resolution due to the performance of

Therefore, conventionally, electrophotography has been known in order to shorten image forming time and improve resolution. However, in the conventional color electrophotographic method, colored particle toner of three colors is sequentially exposed three times and developed and fixed. Color filters and the like for separation are required, which makes the device complicated, and there is also a risk of color shift.

Furthermore, as a method of obtaining a color image with one exposure, there is a method in which particles containing a colorless sublimable dye are charged and adhered to a photosensitive plate and exposed to light, and the dye is colored on a transfer paper. There is also a known method of attaching charged photosensitive particles to a conductive plate and exposing the dye to color the dye on the transfer paper. However, in these methods, organic acids or Images can only be formed on transfer paper on which an inorganic acid is fixed and a coloring layer is formed, which results in high costs and the possibility of fading due to the poor durability of the dye.

Therefore, the present invention was proposed in order to eliminate the drawbacks of the above-mentioned conventional methods, and provides a color image forming method that can easily form a good color image with one exposure. Another object of the present invention is to provide a color image forming method that can perform coloring with extremely high sensitivity in response to color image signals.

In order to achieve the above-mentioned object, the inventors of the present invention conducted intensive research and found that using a colored photoconductive toner in which the photosensitivity wavelength range and the colored absorption wavelength range do not overlap, signal conversion of these toners corresponds to electric color image signals. The present invention was completed by discovering that a color image can be formed with high sensitivity in a single exposure by exposing the toner to red light. A step of uniformly distributing a yellow photoconductive toner that is sensitive to light and a cyan photoconductive toner that is sensitive to blue light on a substrate, a step of charging the above three types of photoconductive toner, and a step of charging the dispersion on the substrate. The method consists of a step of exposing the photoconductive toner to selectively remove the electrical charge, and a step of removing the toner particles from which the charge has been removed from the substrate.

The photoconductive toner used in the present invention is formed by adding a photosensitizer and a coloring material to a photoconductor, and further adding a resin binder for the purpose of fixing on a copying screen.

The above photoconductors include sulfur, selenium, zinc, cadmium, mercury, antimony, and titanium.

Oxides, sulfides, and selenides of bismuth, lead, etc.

Alternatively, anthracene, anthraquinone, polyvinylcarbazole, polyvinylanthracene, polyacetylene and the like can be mentioned. A predetermined sensitizer is added to these photoconductors so that they have a photosensitivity wavelength range in a predetermined visible light region by sensitization using, for example, a dye.

Further, a coloring material having a predetermined colored absorption wavelength range corresponding to the photosensitivity wavelength range of the photoconductor is added, and this coloring material includes various pigments such as organic pigments and inorganic pigments,
Examples include various dyes such as acid dyes, oil-soluble dyes, and direct dyes. These coloring materials can be used alone or in combination depending on the color tone, etc. The above-mentioned resin resultant may include silicone resin,
Examples include thermoplastic resins such as acrylic resin, styrene resin, styrene-butadiene copolymer, polyvinyl alcohol, and polyvinyl acetate, thermosetting resins such as urethane resin, epoxy resin, and melamine resin, and these may be used alone or in combination. used.

Then, each of the above-mentioned materials is formed into particles having a uniformly dispersed structure or a concentric spherical structure by a spray drying method, a microcapsule method, an interfacial polymerization method, or the like to form a photoconductive toner.

By the way, in order to form a color image using the photoconductive toner, it is necessary to make the photoconductive toner into colored particles of three colors that are sensitive to light in the red, green, and blue wavelength ranges. In this case, it is necessary to consider the relationship between the photosensitivity wavelength range and the colored absorption wavelength range.

For example, if each photoconductive toner is colored with the three additive primary colors, red, green, and blue, a color image consisting of the three colors red, green, and blue is obtained as a negative image. However, in this case, the brightness is reversed, and for example, a white part of the image signal becomes black, and a black part becomes white.

On the other hand, when the photoconductive toner is colored in the three primary colors of subtractive color, ie, cyan, magenta, and yellow, a color image consisting of the three colors of red, green, and blue is obtained as a positive image. In this case, the brightness will not be reversed.

When the photoconductive toner is colored with the three primary colors using the subtractive color method, three additional combinations with photosensitizers are possible.

The first is a combination of a cyan photoconductive toner that is sensitive to red light, a magenta photoconductive toner that is sensitive to green light, and a yellow photoconductive toner that is sensitive to blue light. In this case, for example, when exposed to red light, the cyan photoconductive toner is selectively removed and the remaining magenta photoconductive toner and yellow photoconductive toner develop a red color. A positive image of the same color can be obtained. However, in each of these toners, as schematically shown in FIGS. 1(A) to 1(C), the photosensitivity wavelength range a and the colored absorption wavelength range 1 overlap. That is, in the cyan photoconductive toner that is sensitive to red light, as shown in FIG. The wavelength range is 600 to 7 QOnm. Similarly, in the wavelength range of 500 to 600 nm for the magenta photoconductive toner and in the wavelength range of 400 to 500 nm for the yellow photoconductive toner, the sensitivity wavelength range a and the colored absorption wavelength range A overlap each other. .

If the photosensitivity wavelength range and the colored absorption wavelength range overlap in this way, the light of the wavelength to which each toner should be exposed will be absorbed by the coloring material that colors each toner itself, and the photosensitivity will decrease. It will drop significantly.

Therefore, the second combination is a magenta photoconductive toner that is sensitive to red light, a yellow photoconductive toner that is sensitive to green light, a cyan photoconductive toner that is sensitive to blue light, and a third combination that is sensitive to red light. Yellow photoconductive toner, cyan photoconductive toner sensitive to green light.

Examples include magenta light-conducting toners that are sensitive to blue light. The photosensitivity wavelength range a and colored absorption wavelength range of each toner in the second combination above are shown in Figure 2 (A) to Figure 2 (C).
), and the photosensitivity wavelength range a and colored absorption wavelength range of each toner in the third combination are schematically shown in FIGS. 3(A) to 3(C), respectively. It is clear that in any of these combinations, the photosensitivity wavelength range and the colored absorption wavelength range of each toner do not overlap.

Furthermore, according to experiments conducted by the present inventors, the absorbance of a photosensitizer, that is, the spectral characteristics of photosensitivity, shows that the sensitivity decreases sharply at wavelengths longer than the wavelength at which the sensitivity is maximum; It has been found that this sensitivity decreases slowly on the short wavelength side, resulting in a so-called streak, and that there is some sensitivity to short wavelength light in the desired photosensitivity wavelength range. Therefore, if the coloring absorption wavelength range of the coloring material is set to be adjacent to the short wavelength side of the photosensitivity wavelength range, this coloring material will suppress the sensitivity to short wavelength light due to the streaking and act as a filter. This makes it possible to improve the spectral characteristics by limiting the photosensitivity wavelength range to a narrow range.

As a result, it is most preferred to use the second combination, a magenta photoconductive toner sensitive to red light, a yellow photoconductive toner sensitive to green light, and a cyan photoconductive toner sensitive to blue light. That is, as shown in FIG. 2(A), the magenta color photoconductive toner is 60%
It has a photosensitivity wavelength range a from 0 to 700 nm and a colored absorption wavelength range from 500 to 600 nm adjacent to the short wavelength side. Even if it has sensitivity to light, the above-mentioned colored absorption wavelength range overlaps with each other is suppressed. The same applies to the yellow photoconductive toner. Further, since the cyan photoconductive toner has a photosensitive wavelength range af on the shortest wavelength side of 400 to 500 nm as shown in FIG. 2(C), the streaking does not pose a problem.

By the way, the magenta color photoconductive toner (hereinafter referred to as magenta color toner) is sensitive to the red light.

When using a yellow photoconductive toner that is sensitive to green light (hereinafter referred to as yellow toner) or a cyan photoconductive toner that is sensitive to blue light (hereinafter referred to as cyan toner), red light is The irradiated area appears green, the area irradiated with green light appears blue, and the area irradiated with blue light appears red.

Therefore, in order to obtain the correspondence between the colors of the color image signal and the copy image, it is necessary to convert the red signal to blue light, the green signal to red light, and the blue signal to green light. Examples of means for converting electrical color image signals into light for predetermined exposure include a color cathode ray tube two-light emitting diode array having a signal conversion means, a laser beam scanner, and the like.

Next, the process of forming a color image according to the present invention will be explained with reference to the drawings.

First, as shown in FIG. 4, magenta toner (indicated by M in the figure), yellow toner (indicated by Y in the figure), and cyan toner (indicated by C in the figure) are deposited on the conductive substrate 1. ) and then charge the entire surface using a corona charger 2 or the like. At this time, each toner is attracted to the substrate 1 by electrostatic attraction force.

Next, as shown in FIG. 5, light obtained by converting an electric color image signal, for example, blue light obtained by converting a red signal (indicated by B in the figure), and red light obtained by converting a green signal (indicated by R in the figure). ),
A green light (indicated by G in the figure) obtained by converting a blue signal is irradiated. Then, due to the light irradiation, the toner sensitive to each light selectively becomes conductive, loses its charge, and loses its electrostatic attraction to the substrate 1. For example, in a portion irradiated with blue light B, cyan toner C absorbs this light and loses its charge. Similarly, the magenta toner M loses its charge in the area irradiated with the red light R, and the yellow toner Y loses its charge in the area irradiated with the green light G.

Then, as shown in FIG. 6, the toner particles, which have lost their charge and lost their electrostatic attraction, are removed by electrical or mechanical means. In this way, a color image is formed on the substrate 1 in response to the electric color image signal. That is, in the area irradiated with the blue light B obtained by converting the red signal, the cyan toner C is removed and the magenta toner M is removed.
The yellow toner Y remains and appears red. Similarly, in the area irradiated with red light R, cyan toner C
The yellow toner Y remains and exhibits a green color, and the magenta toner M and cyan toner C remain in the area irradiated with the green light G and exhibits a blue color.

The color image thus obtained is fixed using a fixing roller 3, as shown in FIG.

Incidentally, each of the above-mentioned steps can be carried out continuously using a color copying apparatus as shown in FIG.

That is, the recording paper 12 is continuously supplied from the supply roll 11, and the three-color mixed toner M,
Spread Y and C over the entire surface. And these toners M, Y
, C are charged using a corona charger 13, and then the object 14 is irradiated with light from a light source 15, and the obtained electric color image signal is converted into light of a predetermined color by a converter 16 for exposure.

Furthermore, toner particles that have lost their charge due to the exposure are suctioned away using a nozzle 17 and fixed by a fixing roller 18.

As described above, in the present invention, a color image is formed using the above-mentioned magenta toner, yellow toner, and cyan toner by the photoconductive toner charge removal method. It has become possible to form color images easily and with high sensitivity through exposure, and it has become possible to obtain extremely clear color images.

Next, specific preparation examples of the three color toners used in the present invention will be described. It goes without saying that the present invention is not limited to these toners.

[Example of preparation of magenta photoconductive toner sensitive to red light]

Zinc oxide particles SAZEX 2000 (manufactured by Sakai Chemical Industry Co., Ltd.) 4
0 parts by weight, 0.05 parts by weight of tetrabromophenol blue (manufactured by Hanka Kagaku Co., Ltd.), and 80 parts by weight of ethyl alcohol were uniformly dispersed, the ethyl alcohol as a solvent was dried, and the above zinc oxide particles were treated with a photosensitizer. Some of the above tetrabromophenol blue was adsorbed.

Next, add resin binder acrylic resin BR to this dried material.

102 (manufactured by Mitsubishi Rayon Co., Ltd.), 10 parts by weight of Lionol Red (manufactured by Toyo Ink Co., Ltd.), and 7180 parts by weight of acetate were added and mixed using a ball mill to obtain a uniform dispersion. This dispersion was spray-dried using a mini-spray to obtain particulate magenta photoconductive toner.

Figure 9 shows the absorbance characteristics of tetrabromophenol blue, Figure 10 shows the photoconductive properties of zinc oxide sensitized with tetrabromophenol, and Figure 11 shows the photoconductive properties of the resulting magenta color photoconductive toner. show.

From FIG. 11, it can be seen that the magenta color photoconductive toner is
It is clear that it has a sharp photosensitivity around 600 to 700 nm.

[Example of preparation of yellow photoconductive toner sensitive to green light]

Oxidized 11ffl lead particles Zazex 2000 (manufactured by Sakai Chemical Industry Co., Ltd.) 40 parts by weight, Eosin (manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.) 0.2
parts by weight, 80 parts by weight of ethyl alcohol are uniformly dispersed,
Ethyl alcohol, which is a solvent, was dried, and the eosin, which is a photosensitizer, was adsorbed onto the zinc oxide particles.

Next, add resin binder acrylic resin BR10 to this dried material.
2 (manufactured by Mitsubishi Rayon Co., Ltd.), 10 parts by weight of Lionol Yellow (manufactured by Toyo Ink Co., Ltd.), and 180 parts by weight of acetone were added and mixed using a ball mill to obtain a uniform dispersion. This dispersion was spray-dried using a mini-spray to obtain a particulate yellow photoconductive toner.

The absorbance characteristics of eosin are shown in FIG. 12, the photoconductive characteristics of zinc oxide sensitized with eosin are shown in FIG. 13, and the photoconductive characteristics of the yellow photoconductive toner obtained are shown in FIG. 14.

From this FIG. 14, it can be seen that the yellow photoconductive toner is
It is clear that it has extremely high photosensitivity in the vicinity of 500 to 580 nm.

[Example of preparation of cyan photoconductive toner sensitive to blue light]

Zinc oxide particles SAZEX 2000 (manufactured by Sakai Chemical Industry Co., Ltd.)
40 parts by weight, 02 parts by weight of cyanine NK1870 (manufactured by Nippon Kanko Shokuryo Co., Ltd.), and 80 parts by weight of ethyl alcohol are uniformly dispersed, and the ethyl alcohol as a solvent is dried to coat the zinc oxide particles with the cyanine as a photosensitizer. NK1870
was adsorbed.

Next, add resin binder acrylic resin BR10 to this dried material.
2 (manufactured by Mitsubishi Rayon Co., Ltd.) 4 parts by weight, Lionor Blue (
10 parts by weight (manufactured by Toyo Ink Co., Ltd.) and 180 parts by weight of acetone were added and mixed using a ball mill to obtain a uniform dispersion.

This dispersion was spray-dried using a mini-spray to obtain particulate cyan photoconductive toner.

The absorbance characteristics of cyanine NK 1870 are shown in FIG. 15, the photoconductive characteristics of zinc oxide sensitized with cyanine NK 1870 are shown in FIG. 16, and the photoconductive characteristics of the obtained cyan photoconductive toner are shown in FIG. 17. .

From FIG. 17, it can be seen that the cyan photoconductive toner has 4
It is clear that the sensitivity is extremely sensitive in the vicinity of 00 to 480 nm.

The three types of photoconductive toners prepared as described above were charged and coated on plain paper, and irradiated with three colors of light: red, green, and blue. After irradiation, the toner particles that have lost their charge are removed, and the adhering toner particles are fixed, and the red light irradiation area turns green, the green light irradiation area turns blue, and the blue light irradiation area turns red. Colored.

[Brief explanation of the drawing]

Figures 1 to 3 are schematic diagrams for explaining the relationship between the photosensitivity wavelength range and the colored absorption wavelength range of photoconductive toner.
Figure (A) shows a cyan photoconductive toner that is sensitive to red light;
Figure 1 (B) shows a magenta photoconductive toner that is sensitive to green light, Figure 1 (C) shows a yellow photoconductive toner that is sensitive to blue light, and Figure 2 (A) shows a magenta photoconductive toner that is sensitive to red light. Conductive toner, Figure 2 (B) is a yellow photoconductive toner that is sensitive to green light, Figure 2 (C) is a cyan photoconductive toner that is sensitive to blue light, and Figure 3 (A) is a yellow photoconductive toner that is sensitive to blue light. A yellow photoconductive toner sensitive to light, FIG. 3(B), and a cyan photoconductive toner sensitive to green light, FIG. 3(C).
represent magenta photoconductive toners that are sensitive to blue light, respectively. 4 to 7 are schematic diagrams showing the process of forming a color image according to the present invention, in which FIG. 4 shows the photoconductive toner charging step, FIG. 5 shows the exposure step, and FIG. 6 shows the process of removing the charged charge. FIG. 7 shows the toner removal step, and FIG. 7 shows the fixing step. 8th
The figure is a schematic diagram showing an example of a color copying apparatus that can continuously form color images. Figure 9 is a graph showing the absorbance characteristics of tetrabromophenol blue, Figure 10 is a graph showing the photoconductive properties of zinc oxide sensitized with tetrabromophenol blue, and Figure 11 is a graph showing the photoconductive characteristics of zinc oxide sensitized with tetrabromophenol blue.
The figure is a graph showing the photoconductive properties of a magenta photoconductive toner sensitive to red light. Figure 12 is a graph showing the absorbance characteristics of eosin, Figure 13 is a graph showing the absorbance characteristics of eosin.
FIG. 14 is a graph showing the photoconductive properties of zinc oxide sensitized with eosin, and FIG. 14 is a graph showing the photoconductive properties of a yellow photoconductive toner sensitive to green light. Fig. 15 is a graph showing the absorbance characteristics of cyanine NK1870, Fig. 16 is a graph showing the photoconductive properties of zinc oxide sensitized with cyanine NK1870, and Fig. 17 is a graph showing the photoconductive properties of cyan photoconductive toner sensitive to blue light. It is a graph showing characteristics. 1... Conductive substrate 12... Recording paper M... Magenta color photoconductive toner Y that is sensitive to red light.
...Yellow photoconductive toner C sensitive to green light...
Cyan photoconductive toner sensitive to blue light Patent applicant
Sony Corporation Representative Patent Attorney Koike Mimi 1) Sakae Mura - Kan II Figure 11-rJ- and S entry 13th and l Figure 12〉Physician's 1->-11I%J-=- No. 14 Figure 3 Growth lnm1-Jichi Figure 15 □ Missing clause (nm) □

Claims (1)

[Claims] A step of uniformly distributing a magenta photoconductive toner sensitive to red light, a yellow photoconductive toner sensitive to green light, and a cyan photoconductive toner sensitive to blue light on a substrate, and the above three types of photoconductive toners. a step of exposing the charged photoconductive toner spread on the substrate to selectively remove the charge; and a step of removing the toner particles from which the charge has been removed from the substrate. A color image forming method consisting of: