JPH0922141A - Combined photoconductive toner and multicolored image forming method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a toner for forming a clear multicolored image by high- speed printing and to provide an image forming method. SOLUTION: In this multicolored image forming method, a latent image on a photoreceptor is developed by an electrophotographic method using a combined photoconductive toner consisting of two or more kinds of photoconductive toners selected from among yellow, magenta and cyan colors, the quantity of electric charges of the toner of the resultant combined photoconductive toner image is controlled on the basis of image information by exposure with mono-chromatic light in three kinds of specified wavelength regions and the coating weight of the toner to be transferred to paper is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite photoconductive toner used for forming a multicolor image by electrophotography and a multicolor image forming method using the same, and more particularly to a multicolor image by one exposure and one development. And a multi-color image forming method using the same.

[0002]

2. Description of the Related Art The principle of image formation in an electrophotographic apparatus such as a copying machine or a laser printer using an electrophotographic system is that after an electrostatic latent image is formed on an electrophotographic photosensitive member by exposure,
Basically, the electrostatic latent image is developed into a visible image by developing with colored particles called toner constituting a developer, and the toner is transferred and fixed onto a desired sheet. Therefore, various monochromatic images can be obtained by arbitrarily changing the colorant of the toner.

Further, in the case of forming a multicolor image such as a full color image or a multicolor image, four color toners in which black is added to the three primary colors of yellow, magenta, and cyan, if necessary, are sequentially superposed, It develops a desired color. In the case of full color, at least 3 types (4 types if black is included) of toner are required, and basically, a normal single color printing process is performed 3 times (4 if black is included).
It should be repeated).

In the method of forming a full-color image, three (or four) colors, that is, three (or four), of chargers and light sources necessary for the charging and exposing steps for forming an electrostatic latent image which is information of an image are used. ) Or have one set repeated 3 (or 4) times.

The former is called a one-pass method, and high-speed printing is possible, but the apparatus becomes large and the cost becomes high. The latter is 3
It is called a (or 4) pass system, and the device is small and low cost, but low speed printing is performed.

Further, the toner images of three (or four) colors are classified according to whether they are superposed on the photosensitive member or a dedicated transfer member is provided.

The former is called a multi-developing method and is small in size and low in cost, but since the photosensitive member on which a toner image has already been formed must be charged, exposed and developed several times,
In general, accurate color reproduction is difficult and the image quality deteriorates.

The latter is called a transfer body method, and since the transfer body is incorporated, the device becomes large and complicated.

Furthermore, the shapes of the photosensitive member and the transfer member can be divided into drums or belts. Generally, the drum can be rotated with high accuracy and stable image quality can be easily obtained, but the degree of freedom in constructing the device is small and the drum tends to be large. On the other hand, although the image quality of the belt is apt to deteriorate due to meandering or vibration, it has a large degree of freedom in configuring the apparatus and can be made compact.

As described above, each of the methods for forming a multicolor image has advantages and disadvantages, and it is the current situation that methods suitable for the purpose are used in combination.

In recent years, a method of forming an image of two or more colors in one charging-exposure step, which is represented by JP-A-63-123063, has been devised. The basic idea is to capture the surface potential of the electrophotographic photoreceptor at multiple levels and develop with a toner having a charge corresponding to each potential.
It is possible to record independently two positive and negative poles (normal development and reversal development)
Up to. Therefore, in order to form an image of three or more colors by this method, at least two charging-exposure-developing steps are required.

Further, in US Pat. No. 4,125,322, a new multicolor image is developed in which three colors (yellow, magenta and cyan) of photoconductive particles (equivalent to toner) are developed by using an electrophoretic method. Image forming methods have been proposed. According to this document, an apparatus is described in which white light is used and a color filter is installed in an exposure zone, or three types of monochromatic light of blue, green and red are used as a light source. this is,
It is based on the use of photoconductive particles and a light source of three colors and the use of electrophoresis. Therefore, as compared with the conventional electrophotographic apparatus, the electrophotographic photosensitive member is not required, but an electrode structure for the electrophoretic method, a liquid medium supply method, and the like are newly required.

On the other hand, a method of forming a multicolor image using a photoconductive toner is disclosed in JP-A-63-210969 and JP-A-5-224492. According to these, in order to form a multicolor image, each of the photoconductive toners such as yellow, magenta, and cyan is loaded in the developing machine and the electrostatic latent image is developed to develop yellow, magenta and Each cyan toner image is formed. After that, this toner image is arbitrarily exposed to control multiple colors,
It is described to form a multicolor image.

However, in general, Japan Hardc
As described on pages 9 to 12 of the opy '90 paper, the actual charge amount of each toner is different from the initial stage and is influenced by agitation in the developing machine. . Therefore, in this method, it is extremely difficult to uniformly develop the yellow, magenta and cyan toners on the electrophotographic photosensitive member.

[0015]

As described above, when a full-color or multi-color multi-color image is formed in the electrophotographic system, the printing speed of the print is slow because the charging-exposure step is performed twice or more. Since the desired color is realized by overlapping the colors two or more times, the deviation of the color overlap easily occurs. Moreover, the apparatus becomes complicated in the electrophoresis method. further,
When the photoconductive toner is loaded into each developing device and developed, there is a problem that each toner cannot be uniformly developed.

An object of the present invention is to provide a composite photoconductive toner for obtaining a full-color or multi-color multicolor image having a high printing speed and excellent image quality.

Another object of the present invention is to provide a multicolor image forming method using the above composite photoconductive toner.

[0018]

According to the present invention, an electrostatic latent image is formed on an electrophotographic photosensitive member by an electrophotographic method, and the latent image is formed by a composite photoconductive toner having three colors of yellow, magenta and cyan. After development, the toner image is basically irradiated with three types of monochromatic light (red, green and blue) to control color development, and the gist of the present invention is as follows.

First, the toner is a composite photoconductive toner containing a colorant, a binder resin and a photoconductive material, wherein the colorant is at least two colors of photoconductive materials selected from yellow, magenta and cyan. The composite photoconductive toner is characterized in that it is composed of toner.

A latent image formed on the electrophotographic photosensitive member is developed by an electrophotographic method using the above composite photoconductive toner, and the toner image is exposed to monochromatic light of blue, green and red. To form a multicolor image.

The exposure to the above-mentioned toner image is 400 to 49.
0nm blue, 500-560nm green, 600-8
The purpose is to control and expose monochromatic light having different wavelength regions of red to near infrared of 50 nm based on image information.

The monochromatic light exposing means is provided between the developing means and the transferring means in an electrophotographic apparatus having a charging means, an exposing means, a developing means, a transferring means and a cleaner means around the electrophotographic photosensitive member. Achieved by an electrophotographic device.

The photoconductive toner of each color constituting the composite photoconductive toner of the present invention is a constituent material of a conventional electrophotographic toner [colorant, binder resin, auxiliary agent (charge control agent, release agent). Etc.]], a photoconductive material is added, or a part of the constituent materials is replaced with a photoconductive material.

As the photoconductive material, materials known as electrophotographic photoreceptors can be used. For example, polyvinylcarbazole, polyvinylnaphthalene, polyvinylanthracene, polyvinylphenylanthracene, photoconductive polymers such as polyvinylpyrene, monoazo, disazo, trisazo pigments, phthalocyanine pigments, indigo pigments, quinacridone pigments, perylene pigments, isoindoline pigments, pyrylium dyes, Examples thereof include organic pigments and dyes such as benzopyrylium dye, cyanine dye, squaric acid dye, and inorganic semiconductors typified by amorphous Si.

Further, a charge transporting material in a function-separated type electrophotographic photoreceptor composed of a charge generating layer and a charge transporting layer, for example, an oxadiazole compound, an oxazole compound, a pyrazoline compound, a triphenylmethane compound, a hydrazone compound. And the like are used in combination with the organic pigment or dye acting as a charge generating material, the photoconductivity can be remarkably improved, and the charge amount of the photoconductive toner by light irradiation can be easily controlled.

Therefore, by using the charge transporting material, the charge generating material can have both the coloring and charge generating functions of the photoconductive toner, and a photoconductive toner whose charge amount can be easily controlled can be obtained. You can

Specific examples of suitable coloring and charge generating actions include metal or metal-free phthalocyanine pigments as cyan, perylene pigments as magenta, various azo pigments, and isoindoline pigments and various azo pigments as yellow. To be

The photoconductive toner of each color is formed by a pulverization method (preparing toner particles after melt kneading, solution kneading, etc.) or a polymerization method (suspension polymerization, etc.), as in the conventional toner manufacturing method. Simultaneously with the synthesis of the binder resin, each constituent material is uniformly dispersed to prepare the toner).

As the composite photoconductive toner, the photoconductive toners of three colors of yellow, magenta and cyan are prepared, respectively, and then the composite photoconductive toners are melted and put into an apparatus for modifying the surface condition, and the respective colors are melt-bonded. It can be obtained.

On the other hand, regarding the method for forming a multicolor image of the present invention, a conventional electrophotographic apparatus as shown in FIG. 1 can be used, and monochromatic light is controlled and exposed between the developing device 5 and the transfer device 8. The irradiation means (having a light source 6 and a control circuit 7 for controlling the irradiation light amount based on image information) is basically the same as the exposure technique for forming an electrostatic latent image on an electrophotographic photosensitive member. That is, various laser light sources belonging to each wavelength region and a variable wavelength spectroscope are used as the light source 6, and the same control technique as that for forming an electrostatic latent image is used.

When the composite photoconductive toner image is transferred to a recording medium such as paper, the photoconductive toner necessary for the image and
There is a need for a means of separating unwanted photoconductive toner prior to transfer. As an example thereof, a mechanical method, for example, a method of pressing the back surface of the transfer paper 12 with a pressure roll of the transfer device 8 to separate the photoconductive toner particles of the composite photoconductive toner is the most simple and effective. You may perform by methods other than this.

[0032]

The present invention appears to be similar to US Pat. No. 4,125,322, but the fundamental principles of forming a multicolor image are quite different. That is, in the above-mentioned US patent, the electrophoretic method is used as a basic principle, and while applying a voltage between the charge injection electrode and the blocking electrode, the photoconductive particles dispersed in the insulating liquid present between the electrodes are detected. It is exposed to light, and the photoconductive particles are charged according to the amount of exposure to form an image on the electrode.

On the other hand, the present invention has an electrophotographic technique as a basic principle as shown in the schematic view of FIG. That is, a latent image is formed on the electrophotographic photosensitive member 1 by being charged by the charging device 2 on the electrophotographic photosensitive member 1 and exposed by the light source 3 controlled by the control circuit 4 based on an external signal necessary for image formation. It This is developed with the composite photoconductive toner of the present invention filled in the developing device 5 to develop a toner image 11 (for example, a composite photoconductive toner composed of three colors of yellow, magenta, and cyan, at this point Has a black color).

The composite photoconductive toner image 11 has a blue color,
By controlling and exposing three types of monochromatic light of green and red according to image information, the charge amount of the photoconductive toner of each color forming the composite photoconductive toner is controlled, and the transfer paper is used in the transfer process. In this case, the amount of 12 or the like adhered to the recording medium is controlled to provide multicolor.

The transfer image transferred onto the transfer paper 12 by the transfer device 8 is fixed by the fixing device 10. Further, the electrophotographic photosensitive member 1 after the toner image is transferred onto the transfer paper is configured such that the composite photoconductive toner remaining on the surface of the electrophotographic photosensitive member 1 is removed by the cleaner device 9 and the next image formation can be started.

In the multicolor image forming method according to the present invention, the photoconductive toner of each color is individually loaded into the developing machine as disclosed in JP-A-63-210969 and JP-A-5-224492. There is a feature that the image quality is excellent as compared with the case where the image is developed.

In the present invention, the reason that a multicolor image with clear image quality can be obtained at high speed is considered to be as follows.

In the conventional electrophotographic method based on the Carlson method, which essentially requires charging-exposure-development, basically only one color can be expressed by one development. Therefore, in order to obtain a multicolor image, the above-mentioned Carlson method is repeated, and each time the color is adjusted, the surface potential of the electrophotographic photosensitive member is controlled so that the superposition is performed while controlling the amount of each toner deposited. .

On the other hand, according to the present invention, the compound photoconductive toner composed of the photoconductive toner of each color is used to develop in a single step,
Achieved by controlling and exposing monochromatic light to the toner image to control the amount of charge of the photoconductive toner of each color itself and the amount of adhesion of the photoconductive toner of each color to be transferred. Is.

Therefore, in order to obtain a multicolor image by the conventional method, it is necessary to repeat the steps of charging-exposure-developing by the number of toner colors, whereas in the present invention, the above-mentioned steps may be performed once. Since only the exposure for controlling the toner adhesion amount is required, the time required for all steps is short.

Further, according to the present invention, a clear multicolor image having an excellent image quality can be obtained. By combining photoconductive toners of respective colors into a composite photoconductive toner, a latent image is developed. This is because the proportion of each color toner in each dot on the electrophotographic photosensitive member can be made constant.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 140 parts by weight of a resin for toner (FC542, manufactured by Mitsubishi Rayon) and 50 parts by weight of a charge transport material (OX-2, manufactured by Japan Photosensitive Dye Research Institute) were used as tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.). : Special grade reagent) After being dissolved in 806 parts by weight, 4 parts by weight of a yellow colorant (manufactured by Hoechst: Novopalm Yellow 97) was added and stirred to uniformly disperse the colorant.

Next, the above dispersion was dried under reduced pressure and vacuum to completely remove tetrahydrofuran. afterwards,
A photoconductive toner having an average particle size of 8 μm was obtained according to a pulverization method generally used as a method for producing a toner.

In the same manner as above, a magenta colorant (Hoechst Co .: Hostaperm Pink EB) and a cyan colorant (Hoechst Co .: Hostaperm Blue B2G) were used to prepare photoconductive toners of respective colors. .

Next, a surface modification device (manufactured by Nippon Pneumatic Co., Ltd .: device name: fading system) is used to control the supply of the photoconductive toner of each color to thereby control the three colors of yellow, magenta and cyan. A composite photoconductive toner of the present invention composed of photoconductive toner was prepared.

4 parts by weight of the obtained composite photoconductive toner and 96 parts by weight of a carrier (F150 manufactured by Powder Tech Co., Ltd.) were sufficiently mixed to prepare a developer for electrophotography. Further, an electrophotographic photosensitive member was produced according to the method of Example 2 of Japanese Patent Application No. 2-311988.

The produced electrophotographic photosensitive member was tested by the Electrophotographic Society of Japan test chart (1975 edition, N.
o. After forming an electrostatic latent image by the contact exposure of 1-R), it was developed using the above-mentioned developer. Then, after placing the transfer paper on the composite photoconductive toner image, the positive electrode roll charger is pressure-bonded (line pressure: 10 g / cm) to transfer the composite photoconductive toner image to the transfer paper, and the black A composite photoconductive toner image of was obtained.

Next, an electrostatic latent image is again formed on the above electrophotographic photosensitive member, and after development, a spectroscope (manufactured by Nikon: device name: G-250 type) is used for the composite photoconductive toner image. The spectrally red monochromatic light (wavelength: 633 nm) was irradiated, and the composite photoconductive toner image was transferred to the transfer paper by the same method as above. The resulting composite photoconductive toner image was red (consisting of yellow and magenta).

Similarly to the above, after the electrostatic latent image is developed, green monochromatic light (wavelength: 530 nm) and blue monochromatic light (wavelength: 480 nm) are respectively irradiated, and the composite photoconductive toner image is transferred onto the transfer paper. Was done. The resulting composite photoconductive toner image exhibited green (consisting of yellow and cyan) and blue (consisting of magenta and cyan).

Example 2 4.5 parts by weight of the composite photoconductive toner prepared in Example 1 and 95.5 parts by weight of the carrier used in Example 1 were well mixed to obtain a developer.

Next, a laser printer (Hitachi: S
L1000) as a basic device and a spectroscope similar to that of the first embodiment is attached to an external light source so that the composite photoconductive toner image can be irradiated with monochromatic light between the developing process and the transferring process. Was charged with the prepared developer.

Using this apparatus, the wavelength of monochromatic light of the light source 6 for irradiating the composite photoconductive toner image formed on the electrophotographic photosensitive member 1 between the developing step and the transferring step is 633n, respectively.
Changing to m, 530 nm and 480 nm gave red, green and blue images respectively.

[Embodiment 3] Three lasers (helium-neon: 633 nm, neodymium-Yag second harmonic: 532 nm and helium-cadmium) were used after the charging-exposure-developing step of the modified laser printer used in Embodiment 2. : 44
The electrophotographic apparatus was modified so that the composite photoconductive toner image could be irradiated with 2 nm).

By irradiating the composite photoconductive toner image formed on the electrophotographic photosensitive member 1 with each of the above laser beams using this apparatus, a clear multicolor image could be obtained.

Since a multicolor image can be formed by this method only once in comparison with the conventional method which requires three charging-exposure-developing steps, the printing speed can be increased about three times. Further, since there is no step of superimposing the respective colors, it is possible to obtain a clear image without a defect due to an image misalignment.

[0057]

According to the present invention, yellow, magenta,
A latent image formed on an electrophotographic photosensitive member by an electrophotographic method is developed with a composite photoconductive toner composed of three color photoconductive toners of cyan, and the toner image is imaged with three color monochromatic light. By controlling and exposing based on information,
A clear multicolor image can be obtained. Also, high-speed printing,
That is, a multicolor image can be obtained by one charging-exposure-developing.

[Brief description of drawings]

FIG. 1 is a schematic view of an electrophotographic apparatus for realizing a multicolor image forming method according to the present invention.

[Explanation of symbols]

1 ... Electrophotographic photoreceptor, 2 ... Charging device, 3, 6 ... Light source, 4,
Reference numeral 7 ... Control circuit, 5 ... Developing device, 8 ... Transfer device, 9 ... Cleaner device, 10 ... Fixing device, 11 ... Composite photoconductive toner, 12 ... Transfer paper.

Claims (6)

[Claims] 1. A composite photoconductive toner containing a colorant, a binder resin and a photoconductive material, wherein the colorant is at least 2 selected from yellow, magenta and cyan.
A composite photoconductive toner comprising a color photoconductive toner. 2. The composite photoconductive toner according to claim 1, wherein the surface of the photoconductive toner of at least two colors selected from yellow, magenta and cyan is melted and the particles of each color are melt-bonded. 3. A latent image is formed on the electrophotographic photosensitive member by charging the electrophotographic photosensitive member by an electrophotographic method and exposing with a light source controlled based on image information, and the latent image is filled in a developing device. Light of each color constituting the composite photoconductive toner by developing and developing a toner image with the composite photoconductive toner, and controlling and exposing monochromatic light of blue, green and red on the toner image respectively based on image information. What is claimed is: 1. A multicolor image forming method, comprising controlling a charge amount of a conductive toner and controlling an amount of the conductive toner attached to a recording medium in a transfer step, wherein the composite photoconductive toner is a colorant, a binder resin and a photoconductive material. And a colorant composed of at least two colors of photoconductive toner selected from yellow, magenta, and cyan. 4. The monochromatic light has a wavelength of 400 to 490 nm.
(Blue), 500-560 nm (green) and 600-
The multicolor image forming method according to claim 3, wherein the monochromatic light has a wavelength of 850 nm (red to near infrared). 5. A photoconductive toner necessary for image formation and a photoconductive toner unnecessary for image formation are separated by a separating means in a transfer step of transferring the composite photoconductive toner image to a recording medium. Item 4. The multicolor image forming method according to Item 3. 6. The separation means for separating the photoconductive toner necessary for the image formation and the photoconductive toner unnecessary for the image formation by pressing from the back surface of the recording medium. The method for forming a multicolor image according to item 1.