JPH03110419A - Electrophoretic image device - Google Patents

Abstract

PURPOSE:To select the colors of the toners to be developed and to provide a color printer with simple constitution by switching toner selecting light by a toner selecting light projecting mechanism. CONSTITUTION:LEDs of three colors; red, green and blue, are arrayed as the toner selecting light projecting mechanism 204. A laser beam is scanned while the red LED 209a is lighted as the toner selecting light and only the part desired to be formed with an image is irradiated with the laser beam in the case of formation of the cyan toner image. As a result, the negative image of cyan is formed on an insulator side 201 and the positive image on a photosensitive body 205 side. The green LED is similarly lighted at the time of forming the magenta image and the blue LED is lighted at the time of forming the yellow image and the laser beam 210 is scanned as the toner selecting light.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electrophoretic imaging device.

[Prior art] Special Publication No. 21781 of 1960, Special Publication No. 98 of 1960
According to Xerox Corporation's electrophoretic imaging method or photoelectrophoretic imaging method described in No. 70 and others, a cyan powder sensitive to red light and a magenta powder sensitive to green light are added to an insulating liquid. , a yellow powder sensitive to blue light, is used, and the developer is filled between a transparent electrode whose contact surface is conductive and a blocking electrode whose contact surface is insulating, and the developer is filled between a transparent electrode whose contact surface is conductive and a blocking electrode whose contact surface is insulating. By applying an electric field between the electrodes so that powder of each color is attracted to the electrode side, and exposing from the transparent electrode side, a positive image of color according to the spectral characteristics of the exposed light is created on the transparent electrode, while a negative image is blocked. Obtained on the electrode.

[Problems to be Solved by the Invention] However, in the conventional photoelectrophoretic imaging method, in order to perform color printing, it was necessary to expose the image to light of three primary colors: red, green, and blue. For this reason, rather than directly exposing the reflected light or transmitted light from the color document, a laser emitting diode, etc.
When image exposure is attempted using a device in which the printing level of each pixel can be digitally controlled, there is a problem in that it is necessary to prepare three optical writing devices that emit light in each of the three primary colors. Therefore, an object of the present invention is to realize an electrophoresis device that can easily form a full-color image even when using an optical writing device such as a laser light emitting diode, which is difficult to change the emission wavelength range. There is a particular thing.

[Means for solving the problem] An electrophotosensitive member and an insulator are arranged to face each other, and N or more types of electrophotosensitive toners (N is an integer of 2 or more) having different spectral sensitivity characteristics are placed in an insulating solvent. a developing solution having a composition dispersed in the electrophotosensitive toner is filled between the electrophotoreceptor and the insulator, a voltage applying mechanism for applying a voltage between the electrophotoreceptor and the insulator, and The present invention is characterized in that it includes a toner selective light irradiation mechanism that irradiates toner selective light that selectively exposes at least one type of toner, and a photoconductor exposure mechanism that performs optical writing on the electrophotoconductor.

[Effect] The operation of the present invention will be explained based on FIG.

Electrophotosensitive toner T that is sensitive to light A with a certain spectral distribution and not sensitive to light B that has a different spectral distribution from light A.
It is assumed that a developer 103 is used in which toner l' 103a and an electro-photosensitive toner T2103b which is sensitive to light B but not to light A are dispersed in an insulating solvent. Toner Tl
It is assumed that toner 103a and toner T2 103b are both negatively charged at first.

When this developer 103 is filled between the insulator 102 and the electrophotoreceptor 101 and a voltage is applied by the voltage application mechanism 104 so that the electrophotoreceptor 101 side has a higher potential than the insulator 102 side, it becomes negatively charged. Toner Tl 10
3a and T2 103b undergo electrophoresis due to electrostatic force and are attracted to the electrophotoreceptor 101 side.

The toner selection light irradiation mechanism 105 is capable of selectively irradiating light A and light B, and when the developer 103 is irradiated with only light A as toner selection light, only the toner T1103a is exposed to light and becomes electrically active. .

However, in this state, the electrophotoreceptor 101 is not exposed to light and is in a state close to an insulator, and charge movement through the electrophotoreceptor 101 is difficult to occur, so that the toner Tl 103
The injection of charge into a does not result in the charge sign being reversed.

Therefore, while irradiating the light A as the toner selection light, when the photoreceptor exposure mechanism 106 exposes and exposes the part of the electrophotoreceptor 101 where an image is to be formed, that part becomes electrically active and the toner selection light is applied. Charge exchange easily occurs between the toner T1103a activated by the irradiation, and the polarity of the charge of the toner T1103a is reversed. The toner Tl 103a whose charge has been reversed is electrophoresed and attached to the insulator 102 side as indicated by the arrow in FIG. 1 due to electrostatic force. As a result, toner Tl is deposited on the insulator 102.
A negative image 103a and a positive image are formed on the electrophotoreceptor 101. Thus, charge reversal and electrophoresis of the toner particles occurs only when the toner is exposed by the toner selection light and the electrophotoreceptor 106 is exposed by the photoreceptor exposure light.

Furthermore, when the toner selection light is irradiated with light B instead of light A, an image using toner T2 103b can be formed in the same way.

As described above, by switching the toner selection light in the toner selection light irradiation mechanism, it is possible to select the toner to be imaged by the photoreceptor exposure mechanism.

Furthermore, if a toner sensitive to a wavelength range different from Tl 103a and T2 103b is added, and the toner selective light irradiation mechanism can selectively irradiate the light that sensitizes the toner, the types of toner that can be selected can be increased. Since the number of toners can be increased as much as desired, full-color printing is also possible by using a developer containing toners of three or more colors.

The above explanation deals with the case where the toner is negatively charged in its initial state. However, even if the toner is positively charged in its initial state, the voltage on the insulator side is higher than that on the electrophotoreceptor side. The same applies if the voltage is applied by an application mechanism.

[Example] An example of a color electrophoretic imaging device according to the present invention will be described based on the drawings.

FIG. 2 is a diagram showing one embodiment of the present invention.

The insulator 201 is a transparent insulating film, and uses a polyethylene terephthalate (hereinafter referred to as PET) film. On the upper surface of the insulator 201 is a transparent electrode 202 made of a vapor-deposited film of indium tin oxide (hereinafter referred to as IT○).
is formed.

The electrophotoreceptor has a structure in which an electrode 204 is formed on a support 203, and a photoreceptor 205 is further formed on the electrode 204.
is a PET film, the electrode 204 is a transparent IT○ film, and the photoreceptor 205 is an organic photoreceptor film in which a pigment such as phthalocyanine is dispersed in a resin, and has sensitivity in the near-infrared region.

The developer 206 is a cyan toner 20 that is sensitive to red light.
6a, magenta toner 206b sensitive to green light;
The yellow toner 206c, which is sensitive to blue light, is made by dispersing three types of electrically photosensitive toners in an insulating solvent such as kerosene, and these toners are negatively charged in the initial state.

A voltage is applied between the electrode 202 and the electrode 204 by a power source 207 so that the insulator 201 side is at a low potential and the photoreceptor 205 side is at a high potential, forming a voltage application mechanism. Due to the electric field, the negatively charged toner moves and adheres to the photoreceptor 205 side.

The toner selection light irradiation mechanism 209 is an arrangement of three color light emitting diodes (hereinafter referred to as LEDs) of red, green, and blue.
D209a, blue L when developing yellow toner
E'D, green LE when developing magenta toner
D is turned on and the light is irradiated onto the toner layer from above to form toner selection light 209b. In FIG. 2, red light for cyan toner selection is irradiated.

The photoreceptor exposure mechanism uses a laser beam 210 with a near-infrared wavelength.
is scanned by a rotating polygon mirror 211, and the photoreceptor 2
Expose 05.

With the above configuration, when forming a cyan toner image, the laser beam is scanned while the red LED 209a is turned on as toner selection light, and the laser beam is irradiated only on the portion where image formation is desired.

As a result, a cyan negative image is formed on the insulator 201 side, and the photoreceptor 2
A positive image is formed on the 05 side. Similarly, when forming a magenta image, the green LED is turned on, and when forming a yellow image, the blue LED is turned on as toner selection light.
Scan the laser beam 210. In this way, by switching the toner selection light and exposing the photoreceptor three times, a full-color image using the three primary colors of cyan, magenta, and yellow is formed. The toner selection light may be switched in any order, such as pixel sequential, line sequential, or surface sequential.

Furthermore, either a positive image on the photoreceptor 205 or a negative image on the insulator 201 may be used as the image. The negative image on the insulator 201 can be created by developing toner images of each color multiple times at the same location, or by developing each color separately and transferring each color toner image onto one transfer medium in a subsequent process such as transfer. They may be superimposed on top of each other.

FIG. 3 is a diagram showing another embodiment of the present invention.

A corona discharger 320 is used in place of the power source 207 in FIG.
This embodiment is different from the embodiment shown in FIG. 2 in that the light source 09 is disposed on the photoreceptor 205 side, and the toner selection light is transmitted through the photoreceptor 205 and irradiated onto the toner. In this embodiment, the insulator 3
01 may also be made of an opaque material such as alumina ceramics. In the case of the embodiment shown in FIG. 3, it is necessary to use a photoreceptor that is not sensitive to the toner selection light but has the property of transmitting it. Further, contrary to the embodiment shown in FIG. 3, a configuration in which both the photoreceptor exposure light and the toner selection light are irradiated from the insulator side through the insulator is also possible.

In that case, the electrode 204 and the support 203 do not need to be transparent.

FIG. 4 is a diagram showing still another embodiment of the present invention, in which the distance between the photoreceptor 205 and the insulator 401 is widened near the developing section, so that the toner selection light cannot pass through the electrophotoreceptor or the insulator. The structure is such that it can directly irradiate the developing area. Also,
In this embodiment, an LED array 410 in which a large number of LEDs are arranged one-dimensionally is used as a photoconductor exposure mechanism, and photoconductor exposure light 410a from the LED array 410 is directed onto the photoconductor 205 by an imaging optical system 411. An image is formed and exposed. In this embodiment as well, the insulator 401 and the electrode 402 do not need to be made of transparent materials, and the electrode 402 may be made of a material such as aluminum. Furthermore, in this embodiment, the insulator 401 side is not flat but curved, but a configuration may also be adopted in which curvature can also be provided on the electrophotoreceptor side. The insulator or the electrophotoreceptor may have a cylindrical shape or the like.

In the above embodiments, a developer was used in which three types of electrophotosensitive toners, yellow, magenta, and cyan, which are sensitive to blue, green, and red toner selection lights, were dispersed. may be other than this, and the toner selection light may be light in the infrared or ultraviolet region. Further, the combination of the light to be exposed to and the color to be developed may be different. Further, by using a toner containing a leuco dye, a color different from the initial color may be developed through a coloring step after development. Further, toners of four or more colors may be used, or if full colors are not required, only two appropriate colors may be used. For example,
In some cases, a developer is used that consists of four types of electrophotosensitive toners that are exposed to infrared, red, green, and blue toner selective light and ultimately develop colors of cyan, magenta, and yellow black. can give.

Further, the toner selection light irradiation mechanism may be configured as long as it can irradiate at least toner selection light corresponding to the type of toner desired to be selected. In addition to using a plurality of color LEDs that emit light for each toner selection light as in the embodiments of FIGS. 2 to 4, various light sources such as cold cathode tubes and electroluminescence light sources can be used. Further, if a color cathode ray tube or the like is used, it becomes possible to irradiate many types of toner selection light with one light source. Alternatively, a configuration may be adopted in which a light source having multiple wavelength components, such as a white fluorescent lamp or a halogen bulb, is used, and a filter that extracts only the necessary wavelength range is combined, and the toner selection light is switched by switching the filter.

Further, in the present invention, there is no restriction on the order in which the toner selection light is switched, and the toner selection light may be switched on a screen-by-screen basis, or may be switched on a line-by-line or pixel-by-pixel basis. Furthermore, if full color is not required, only the toner of the desired color may be selected and exposed and developed.

In addition to lasers, there are also L
Various light sources such as ED and cathode ray tubes can be used, and a shutter element such as a liquid crystal shutter may be used in combination with other light sources. In addition to exposing the entire screen by scanning one beam as in the embodiments shown in FIGS. 2 and 3, an exposure mechanism in which a plurality of exposure elements are arranged one-dimensionally or two-dimensionally may be used. . Further, optical scanning may be performed by moving one or both of the light source and the photoreceptor. Further, the exposure wavelength does not need to be near infrared, and light with any spectral distribution may be used as long as it can expose the photoreceptor.

In addition to organic photoreceptors, photoreceptors include amorphous silicon,
Materials with various spectral sensitivity characteristics such as selenium can be used, and the carrier generation part and carrier transport part are functionally separated.
A photoreceptor with a composite structure may also be used. Further, the support body 203 is not necessarily required unless there is a problem in terms of strength.

Further, in the above embodiments, the toner is initially negatively charged and a voltage application mechanism is used that makes the insulator side have a lower potential than the photoreceptor side.
A reverse polarity voltage application mechanism that makes the insulator side have a high potential may be used.

[Effects of the Invention] According to the configuration of the present invention, even if image exposure is performed using a single photoreceptor exposure mechanism, the color of the toner to be developed can be selected by simply switching the toner selection light using the toner selection light irradiation mechanism. . Therefore, there is no need to have a plurality of photoreceptor exposure mechanisms for each color, and there is no need to use a different developer for each color.

Therefore, a color printer can be realized with a very simple configuration. In addition, another effect is that color printers can be realized by using exposure devices, such as laser exposure devices and light emitting diode arrays, that have traditionally been used as exposure devices for monochrome electrophotographic printers as photoconductor exposure mechanisms. have

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail. FIG. 2 is a diagram showing one embodiment of the present invention. FIG. 3 is a diagram showing another embodiment of the present invention. FIG. 4 is a diagram showing still another embodiment of the present invention. that's all

Claims (1)

[Claims] An electrophotoreceptor and an insulator are arranged to face each other, and a developer is prepared in which N or more types of electrophotosensitive toners (N is an integer of 2 or more) having different spectral sensitivity characteristics are dispersed in an insulating solvent. , a voltage applying mechanism that applies a voltage between the electrophotoreceptor and the insulator, and at least one of the electrophotosensitive toners is selectively photosensitive. An electrophoretic imaging apparatus comprising: a toner selective light irradiation mechanism that irradiates a toner selective light such that the toner selective light is applied; and a photoconductor exposure mechanism that performs optical writing on the electrophotoconductor.