WO2007099597A1

WO2007099597A1 - Image forming method and image forming device

Info

Publication number: WO2007099597A1
Application number: PCT/JP2006/303737
Authority: WO
Inventors: Hisanobu Matsuzoe
Original assignee: Fukuoka Technoken Kogyo, Co., Ltd.
Priority date: 2006-02-28
Filing date: 2006-02-28
Publication date: 2007-09-07
Also published as: JPWO2007099597A1; JP4181624B2

Abstract

An image forming method is provided to achieve features in which an image formed on a recording medium is fixed and displayed for a long time, the occurrence of a color shift is surely prevented under simple control, a high quality image is formed without a fine adjustments between a heating and electric discharge type printing head or an image forming device and a recording medium, and a productivity is good. The image forming method forms an image on the recording medium provided with a surface layer made from an electrophoresis system image display material in which colored particles are dispersed in carrier fluid softened by heating energy applied to the heating and electric discharge type printing head. The image forming method is comprised of a softening step for heating the recording medium to soften the carrier fluid, an electric potential difference setting step for setting an electronic potential difference corresponding to an electro discharge control voltage between the recording surface of the recording medium and counter electrodes provided on a surface opposite to the recording surface, and an electric discharge electrode heating step for selectively heating the electric discharge electrodes in accordance with image information.

Description

Image forming method and image forming apparatus

Technical field

In the present invention, an image is formed by selectively applying a charge to an electrostatic development type recording medium by a heat-discharge type print head, and the image is fixed and displayed for a long period of time. The present invention relates to an image forming method and an image forming apparatus.

Background art

In recent years, as shown in (Patent Document 1), an ion irradiation method, which is an electrostatic latent image forming method different from the electrophotographic method, has been developed.

The electrophotographic method uses two processes, uniform charging and exposure, to release the exposed portion of the charge on the uniformly charged photoconductor, thereby forming an electrostatic latent image on the photoconductor as the electrostatic latent image carrier. On the other hand, in the ion irradiation method, in an atmosphere where ions can be generated (such as in the air), selective charging by irradiation of ions generated by the discharge of electrons from the discharge electrode (electrostatic latent image formation charging) Since the formation of the electrostatic latent image can be completed on the electrostatic latent image carrier (there is no need to be a photosensitive member as long as it is an insulator), an image can be formed more easily. it can.

Further, (Patent Document 2) discloses a specific shape of an ion irradiation type print head compatible with a horizontal printer and an image forming apparatus including the shape.

In particular, as shown in (Patent Document 1) and (Patent Document 2), a state in which discharge is not generated just by being applied to the discharge electrode but a voltage that generates a discharge by heating (discharge control voltage) is applied. Therefore, the heating / discharging method in which discharge is performed by selective heating of the discharge electrode is the best from the viewpoint of controlling discharge because a driver IC that supports low withstand voltage such as 5V drive can be used to control heating. Control method. For this reason, it is an optimal print head that can be conceived at present for writing in a non-contact manner on a recording medium of an electrostatic development system generally called a digital paper.

Incidentally, as a digital paper at the present time, a minute ball is color-coded into two colors (for example, black and white), and the ball is rotated according to the electrical characteristics of each color to display any one color. Twisted ball method, electrophoretic method in which fine powder of two colors (for example, black and white) is mixed in a minute ball, and only one color is floated and displayed due to the difference in electrical characteristics of the fine powder of each color, liquid crystal plate or There is a liquid crystal system that opens and closes the liquid crystal shutter of a small liquid crystal block and displays the background color of the part where the shutter is opened.

Since these electrostatic development type recording media form an image by an electric field, when a charged person touches the image, the image is rewritten over time due to the effect of the charge, and the image is displayed continuously. The image quality was unreliable, and the application was limited to those that rewrite the image in a short period of time.

In order to solve this problem, for example, (Patent Document 3) describes a microcapsule in which charged particles that can migrate in the electric field direction and a dispersion medium that disperses the charged particles are enclosed. The microcapsule is characterized in that the medium has a curable material that is cured by energy applied from the outside. "

Further, (Patent Document 4) states that “a rela- tor in which a large number of microcapsules containing dispersed particles having different colors and electrification and wax that softens and thickens at a high temperature are dispersedly arranged. "Itable sheet" is disclosed.

Patent Document 1: Japanese Patent Laid-Open No. 2003-326756

Patent Document 2: Japanese Patent Application 2004-069350

Patent Document 3: Japanese Patent Laid-Open No. 2003-215642

Patent Document 4: Japanese Patent Laid-Open No. 11-161205

Disclosure of the invention

Problems to be solved by the invention

However, the conventional technology described above has had the following problems.

(1) Since the image forming apparatuses of (Patent Document 1) and (Patent Document 2) perform writing while relatively moving the heat-discharge type print head and the recording medium, in order to improve image quality and color. Is required to control the positioning of the heat-discharge-type print head and the recording medium and the timing of ion irradiation, etc., and it is difficult to achieve high image quality and color. It became a challenge.

(2) The microcapsules of (Patent Document 3) give external light or thermal energy. The rewritable sheet of (Patent Document 4) forms an image by reducing the viscosity of the wax by heating means when forming an image, and after cooling, the image is formed after cooling. Can be maintained stably. However, in order to form a desired image on these recording media and rewritable sheets, one of the pair of electrode portions must be formed as a matrix pixel electrode corresponding to each pixel of the recording medium. However, in order to drive these, it is necessary to arrange a thin film transistor corresponding to each pixel electrode, which has a problem of lack of productivity and low cost as a recording medium.

[0004] The present invention solves the above-described problems, and an image can be formed in units of colors by a heat-discharge type print head on a recording medium using an electrophoretic thermal recording material as an image display material. The formed image can be fixed and displayed over a long period of time, and it is possible to reliably prevent the occurrence of color misregistration by forming an image on the recording medium with simple control. Providing a highly productive image forming method capable of forming a high-quality image without finely aligning the heating discharge type print head or image forming apparatus with the recording medium, and improving the image quality. An object of the present invention is to provide an image forming apparatus which is excellent in reliability, can be simplified in structure with only a recording medium as consumables necessary for forming a color image, is easy to maintain and has excellent resource saving.

Means for solving the problem

In order to solve the above problems, an image forming method and an image forming apparatus of the present invention have the following configurations.

The image forming method according to claim 1 of the present invention uses a heat discharge type print head comprising a discharge electrode having an electron emission site and a heating means for selectively heating the discharge electrode.

V. An image forming method for forming an image on a recording medium having a display layer using an electrophoretic image display material in which colored particles are dispersed in a dispersion medium that is softened by thermal energy. A softening step of softening the dispersion medium by heating the medium; and a recording medium disposed on a surface opposite to the recording surface of the recording medium disposed opposite to the discharge electrode and the heat-discharge type print head. A potential difference setting process for forming an electric field by setting a potential difference corresponding to the discharge control voltage between the counter electrode and the opposite electrode, and based on image information! A discharge electrode heating step of selectively heating the discharge electrode. This configuration has the following effects.

(1) In the potential difference setting step, a potential difference corresponding to the discharge control voltage is set between the discharge electrode and the counter electrode to form an electric field. Since the discharge can be generated simply by selectively heating the discharge electrode, it is not necessary to control the high voltage, and it is possible to easily control the generation of the discharge and charge the recording medium to display an image. .

(2) The voltage value applied to each of the discharge electrode and the counter electrode can be arbitrarily set so that the potential difference between the discharge electrode and the counter electrode becomes equal to the discharge control voltage in the potential difference setting step. The voltage applied to the counter electrode can be optimally adjusted according to the type and characteristics of the recording medium, and the versatility is excellent.

(3) In the softening process, the recording medium is heated to soften the dispersion medium, and then an image is formed by the potential difference setting process and the discharge electrode heating process. Therefore, when the recording medium cools, the dispersion medium hardens. The image formed on the recording medium can be fixed, and it is possible to easily form an image with excellent image quality stability that is not affected by environmental changes and static electricity and does not change over time. it can.

[0006] Here, the discharge control voltage means that no discharge occurs between the discharge electrode of the heat-discharge type print head and the counter electrode of the recording medium only by the potential difference, but the discharge electrode is heated. The voltage range where discharge occurs. The discharge here means that discharge electrode force electrons are emitted. The emitted electrons ionize oxygen and nitrogen in the atmosphere and make them reach the recording surface of the recording medium.

A potential difference corresponding to the discharge control voltage is set between the discharge electrode and the counter electrode to form an electric field, and the discharge electrode can be controlled by heating the discharge electrode with the heating means. By selecting the location, electrons can be easily emitted selectively from the vicinity of any heating position (electron emission site) of the discharge electrode to generate a discharge.

[0007] For example, the discharge electrode is formed in a comb shape by connecting one end of a plurality of electron emission sites with a common electrode, or formed in a ladder shape or the like by connecting both ends of a plurality of electron emission sites with a common electrode In addition, it can be formed into a single flat plate shape such as a rectangular shape or a square shape (see, for example, JP-A-2003-326756, WO2005Z056297).

By providing a common electrode in the vicinity of the electron emission site, such as a comb-type or ladder-type, the cooling area of the discharge electrode and the responsiveness to heating stop are improved by increasing the heat radiation area of the discharge electrode and increasing the heat capacity. In addition, since a stable voltage can always be applied by reducing the resistance value, the stability of discharge can be further improved. Note that the discharge electrode formed in a flat plate shape is a common electrode except for the electron emission site.

In particular, when the width of the common electrode is wider than the width of the electron emission site, the cooling effect of the discharge electrode, which is temporarily heated to 100 to 300 ° C, is improved, and heat can be prevented from being burned. In addition, the discharge can be stopped in response to the heating off quickly, the discharge time interval can be shortened and the presence / absence of the discharge can be switched in a short time, and the recording speed can be increased. In addition, the resistance value of the common electrode can be reduced, and the potential difference generated between the electron emission sites connected by the common electrode can be suppressed as much as possible. The discharge stability is excellent.

[0008] The discharge electrode is formed by depositing a metal such as gold, silver, copper, or aluminum on a substrate by vapor deposition, sputtering, printing, plating, etc., and then etching to form a pattern as necessary. Stainless steel, copper In addition, a material in which at least a part of a metal such as aluminum is thinned by etching, cutting, or the like, and then patterned by etching, laser caching, or the like is suitably used. In addition, the discharge electrode may be formed using a conductive material such as carbon.

When the discharge electrode is formed on the substrate, the material of the substrate may be any material as long as the discharge electrode can be formed on the surface and has heat resistance to withstand the heating by the heating means. Further, when heating is performed from the back side of the substrate by the heating means, those having a heat transfer property capable of transferring heat generated by the heating means to the discharge electrode are preferably used. Specifically, synthetic resins such as glass, polyimide, aramid, and polyetherimide are preferably used.

When the discharge electrodes are formed in a comb shape, the shape of each electron emission site can be formed in a substantially rectangular shape, a trapezoidal shape, a semicircular shape, a bullet shape, or a combination thereof. In addition, a part of the electron emission site can be further divided by slits, etc. To increase the circumference around the edge of the electron emission site (for example, WO

2005Z056297). Since the discharge electrode emits a large amount of electrons from the periphery of the edge, it is possible to increase the amount of emitted electrons and the intensity of emitted light by increasing the amount of electron emission of the discharge electrode force by increasing the circumference around the edge. In addition, the discharge control voltage and heating temperature can be set low, and the energy saving and discharge generation efficiency are excellent. In addition, since the discharge control voltage can be set low, the discharge electrode has excellent long life.

Instead of dividing the end portion of the discharge electrode or forming the uneven portion on the peripheral edge portion, a discharge hole portion may be formed in the vicinity of the electron emission site (heating position). As a result, electrons can be emitted from the peripheral edge of the discharge hole, and the same effect as dividing the end of the discharge electrode can be obtained. The shape of the discharge hole portion can be formed in various shapes such as a substantially circular shape, a substantially elliptical shape, a polygonal shape such as a quadrangle and a hexagon, and a star shape. Further, the number and size of the discharge hole portions per one electron emission site (near the heating position) can be appropriately selected and combined. Note that the concave and convex portions and the discharge holes of the discharge electrode can be formed by the above-described etching or laser processing.

[0010] Further, a conductive material layer may be formed on at least the surface of the common electrode among the discharge electrodes.

As a result, the resistance value of the common electrode can be further reduced, the potential difference generated between each electron emission site can be reliably reduced, and the discharge stability is excellent. The conductive material layer only needs to have conductivity superior to that of the discharge electrode, and can be easily formed by silver paste screen printing or silver plating. By increasing the thickness of the conductive material layer, the resistance value of the common electrode can be reduced, and the discharge stability can be improved.

The thickness of the discharge electrode is preferably 0.1 μm to 100 m when it is formed with a force plate depending on the material. The discharge electrode tends to be affected by wear as the thickness of the discharge electrode becomes thinner than 0. m, and the life of the discharge electrode tends to be shortened. As the thickness exceeds 100 m, the heat capacity increases, and the response to heating on and off is increased. There is a tendency to be easily lowered, and deviation is not preferable. By reducing the thickness of the discharge electrode to 100 m or less, it is possible to quickly recover from the heated state and to increase the printing speed.

[0011] The display layer of the recording medium is filled with an electrophoretic image display material! RU There are two types of electrophoretic image display materials colored in different colors such as white and black. Color display in combination with a color filter with the three primary colors (R, G, B) in the additive color mixing method and a reflective layer with the three primary colors (Y, M, C) in the subtractive color mixing method. It can be performed. Instead of combining with color filters and reflective layers, color display is performed by coloring display primary colors (Y, M, C), etc., in the subtractive color mixture method except for colored particles that display a background color such as white. You can also. For example, select two or more display primaries by combining two types of colored particles colored in one of white and multiple display primaries in a space partitioned by microcapsules or partition walls together with a dispersion medium. Can be displayed automatically. White and black or display primary colors if at least one of the two types of colored particles encapsulated together in a space separated by one microcapsule or partition wall is positive or negatively charged Can be selectively displayed. When only one of the two types of colored particles is a charged electrophoretic particle, the other is dispersed as fine particles having a smaller particle size than the electrophoretic particle, thereby preventing movement of the electrophoretic particle. It is possible to selectively display white and black or display primary colors. When one of the two kinds of colored particles is a positively charged electrophoretic particle and the other is a negatively charged electrophoretic particle, each colored particle can be reliably moved by the charge, and the operation stability is excellent.

As the dispersion medium, a dispersion medium that softens and decreases in viscosity when heated is used. It is preferable to use a combination of dispersion media having different softening temperatures for colored particles having different display primary colors. Examples of such a dispersion medium include aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, various esters, alcohol solvents, other oils, and mixtures thereof, polyalkylene or natural hydrocarbons. A mixture of waxes can be used. As such wax, polyethylene, polypropylene, carnauba wax, candelilla wax, rice wax, amide wax, ketone wax and the like can be used. In particular, it is preferable to use one having a relatively uniform molecular weight in which the viscosity curve with respect to temperature in the range of 20 to 40 cps changes sharply. This is to increase temperature sensitivity.

If there are two or more display primaries for color display, it is possible to select an appropriate combination of colors. Note that the display primary color of the color display is at least the three primary colors (Υ, M , C), full color display can be performed. It is also possible to divide the display layer of one recording medium into multiple areas and display different colors for each area.

In this recording medium, as described above, a potential difference corresponding to the discharge control voltage is set between the discharge electrode and the counter electrode, and a discharge is generated by selectively heating the discharge electrode. Can be formed. Therefore, all the voltages corresponding to the discharge control voltage may be applied to the discharge electrode side and the counter electrode may be grounded, or the voltage corresponding to the discharge control voltage may be distributed to the discharge electrode and the counter electrode side. It may be applied.

The grounding and voltage application to the counter electrode may be selectively performed. If the counter electrode is formed in a strip shape corresponding to each row or column of the display pixels of the recording medium instead of forming a common counter electrode over the entire surface of the recording medium, the selection control of the counter electrode is easy. Selective grounding and voltage application can be easily performed.

When this counter electrode and Z or discharge electrode are divided and formed corresponding to the arrangement of the display primary colors of the recording medium, the counter electrode and z or discharge electrode are selected according to the color units of the display primary colors of the recording medium and grounded. Therefore, it is possible to form an image by dividing the image information into color units, and in particular for a color image, it is possible to reliably prevent color misregistration and obtain a high-quality image.

[0014] In the softening step, the recording medium may be heated to soften the dispersion medium before forming all the images, or the region force for forming the images may be sequentially performed. It's okay.

In addition, when the image formation is performed in units of colors, the recording medium may be heated every time an image of each color is formed. In this case, it is preferable to use a recording medium having a display layer using an image display material in which a dispersion medium having a different soft temperature corresponding to the display primary color of the colored particles is enclosed. This is because, by changing the heating temperature according to the type of the dispersion medium, an image can be written in color units, and color misregistration can be reliably prevented.

[0015] The heating discharge type print head sets a potential difference corresponding to a discharge control voltage between the discharge electrode and the counter electrode in the potential difference setting step, and selectively heats the discharge electrode in the discharge electrode heating step. Therefore, the discharge electrode heating process can be performed after the potential difference setting process, and the potential difference setting process and the discharge electrode can be controlled. You may perform a heating process simultaneously.

When the image display material of the recording medium is arranged in a striped pattern for each display primary color, the counter electrode should be formed in a strip shape corresponding to the image display material arranged in the striped pattern. Is preferred. Accordingly, the counter electrode can be easily selected in color units, and electrons are selectively emitted from the electron emission site of the discharge electrode corresponding to the selected counter electrode, and the electrons and ions are recorded on the recording surface of the recording medium. The desired position can be irradiated to obtain a high-quality color image without color shift. Since an image can be arbitrarily formed by selecting a counter electrode for each color unit of the image display material, color misregistration does not occur in the image formation process, so heating of the recording medium by the softening process forms all images. It can be done together before. For this reason, only one type of dispersion medium is used for the recording medium and only one heating operation is required, so that the number of man-hours required for image formation can be reduced.

The image forming method according to claim 2 of the present invention uses a heat discharge type print head provided with a discharge electrode having an electron emission portion and a heating means for selectively heating the discharge electrode, by thermal energy. An image forming method for forming an image on a recording medium having a display layer using an electrophoretic image display material in which colored particles are dispersed in a curing dispersion medium, wherein the discharge electrode and the heat discharge type printing are used. A potential difference in which an electric field is formed by setting a potential difference corresponding to a discharge control voltage between a counter electrode formed on a surface opposite to the recording surface of the recording medium, the recording surface being disposed facing the head. A setting step; a discharge electrode heating step for selectively heating the discharge electrode based on image information; and a curing step for curing the dispersion medium by heating the recording medium. Talk! With this configuration, the following effects can be obtained.

(1) In the potential difference setting step, a potential difference corresponding to the discharge control voltage is set between the discharge electrode and the counter electrode to form an electric field. Since the discharge can be generated simply by selectively heating the discharge electrode, it is not necessary to control the high voltage, and it is possible to easily control the generation of the discharge and charge the recording medium to form an image. .

(2) The voltage value applied to each of the discharge electrode and the counter electrode is arbitrarily set so that the potential difference between the discharge electrode and the counter electrode becomes equal to the discharge control voltage in the potential difference setting step. Therefore, the voltage value applied to the counter electrode can be optimally adjusted according to the type and characteristics of the recording medium, and the versatility is excellent.

(3) During the curing process, the recording medium can be heated to cure the dispersion medium to fix the image formed on the recording medium, making it less susceptible to environmental changes and static electricity. It is possible to easily form an image with excellent image quality stability that does not change over time.

Here, since the discharge control voltage, the discharge electrode, the electrophoretic image display material, and the potential difference setting process are the same as those described in claim 1, the description thereof is omitted.

[0018] A dispersion medium that cures when heated is used. For the colored particles having different display primary colors, it is preferable to use a combination of dispersion media having different softening temperatures. A thermosetting resin can be used as such a dispersion medium. As thermosetting resin, polyisocyanate, epoxy, acrylic, silicone, polyurethane, urea, phenol, formaldehyde, epoxy polyamide, melamine, alkyd resin, etc. should be used. Can do. In particular, a thermosetting resin having a glass transition temperature of 60 to 150 ° C. is preferably used. When the temperature is lower than 60 ° C, the weather resistance of the image is deteriorated and the image disappears with time. When the temperature is higher than 150 ° C, the handling property is reduced.

[0019] In the curing step, the recording medium is heated to cure the dispersion medium, after all the images are formed, or the region force after the image formation is completed may be sequentially performed. Good.

Further, when image formation is performed in units of colors, the recording medium may be heated each time recording for each color is completed. In this case, it is preferable to use a recording medium having a display layer using an image display material in which a dispersion medium having a different curing temperature corresponding to the display primary color of the colored particles is enclosed. This is because by changing the heating temperature according to the type of the dispersion medium, it is possible to reliably prevent the occurrence of color shift by fixing the image in units of colors.

[0020] The invention according to claim 3 is the image forming method according to claim 1 or 2, wherein the potential difference setting step is performed by a head-side voltage application unit electrically connected to the discharge electrode. The head side voltage applying step for applying a voltage to the discharge electrode and the medium side voltage control unit electrically connected to the counter electrode performs grounding or voltage application to the medium electrode. A medium-side voltage control step.

With this configuration, in addition to the operation of the first or second aspect, the following operation is provided.

(1) The potential difference setting step includes a head side voltage application step in which a voltage is applied to the discharge electrode by a head side voltage application unit electrically connected to the discharge electrode, and a medium side voltage electrically connected to the counter electrode. Medium-side voltage control process in which the control unit performs grounding or voltage application to the counter electrode, so that voltage is applied to the entire discharge electrode in the head-side voltage application process, and grounding of the counter electrode is performed in the medium-side voltage control process. Alternatively, by applying a voltage, a potential difference corresponding to a discharge control voltage can be selectively generated between the discharge electrode and the counter electrode to prepare for the discharge.

Here, if the voltage applied to the discharge electrode side by the head-side voltage application unit is set to be equal to or slightly lower than the discharge control voltage, the medium-side voltage control unit sets the counter electrode to A potential difference corresponding to the discharge control voltage can be set selectively by simply grounding or controlling and applying a relatively low voltage that only compensates for the shortage of the discharge control voltage. By controlling the heating, the recording surface of the recording medium can be reliably irradiated with electrons and ions to impart electric charges. In addition, since the head-side voltage application unit controls the voltage application to the entire discharge electrode, the presence / absence of voltage application can be easily controlled even when the voltage applied to the discharge electrode side is a high voltage.

In the heat-discharge type print head, discharge is not generated only by setting a potential difference corresponding to the discharge control voltage between the discharge electrode and the counter electrode! Therefore, the discharge electrode is used as a subsequent process of the medium side voltage control process. A heating step may be performed, and the medium-side voltage control step and the discharge electrode heating step may be performed simultaneously.

[0022] The invention according to claim 4 is the image forming method according to any one of claims 1 to 3, wherein the potential difference setting step, the discharge electrode heating step, the softening step, or the The curing process is repeated for each color of the display primary color of the recording medium, and the temperature at which the recording medium is heated in the softening process or the curing process has a configuration that differs for each color of the display primary color. And then.

With this configuration, the following actions are taken in addition to the actions of the fifth or sixth aspect.

(1) The potential of the recording medium is determined by the potential difference setting process, the discharge electrode heating process, the softening process or the curing process By repeating the display for each primary color of the color display, it is possible to divide the image information into color units to form an image, prevent occurrence of color misregistration, and fix the formed image. Thus, it is possible to obtain a high-quality and reliable color image that does not change with time.

(2) Since the recording medium can be heated at a temperature equal to or higher than the softening temperature or curing temperature of the dispersion medium corresponding to the color of the display primary color by the softening process or the curing process, the color can be changed over the discharge electrode heating process. By heating the recording medium each time an image of a unit is formed, rewriting or fixing of an image formed in units of colors can be sequentially performed, and the occurrence of color misregistration can be effectively prevented.

Here, the potential difference setting process, the discharge electrode heating process, the softening process, or the curing process is repeated for the number of display primaries for color display. Only the image display material that displays the desired display primary color can be selectively fixed during the curing process, and only the image display material that displays the desired display primary color can be selectively written during the soft process. As a result, at the stage of forming an image in the discharge electrode heating process, there is no need for high accuracy with respect to the irradiation position of electrons and ions, so there is no need to divide the counter electrode into color units. The medium side voltage control process can be simplified. Since the counter electrode can be formed as a single flat plate such as a common rectangular shape or square shape over the entire surface of the display medium, fine alignment between the display layer of the recording medium and the counter electrode is also unnecessary. In this case, the counter electrode can be provided on the apparatus side without being provided on the recording medium side. For example, by forming the counter electrode on the surface of the flat recording medium mounting portion on which the recording medium is mounted, the back surface of the recording medium and the counter electrode can be reliably brought into contact with each other. An image can be formed while moving the recording medium placement portion horizontally.

[0024] The invention according to claim 5 is the image forming method according to any one of claims 1 to 4, wherein the medium side voltage control step is selectively performed based on image information. It has a structure.

With this configuration, in addition to the operation of any one of claims 1 to 4, the following operation is provided.

(1) Since the medium side voltage control process can be performed in synchronization with the discharge electrode heating process, It is possible to prevent the occurrence of discharge due to operation, and it is excellent in control reliability and high image quality.

Here, when a part of the discharge control voltage is applied to the counter electrode by the medium side voltage control unit, an unnecessary voltage is applied by selectively performing the medium side voltage control step based on the image information. Excellent energy saving.

[0025] The invention according to claim 6 is the image forming method according to claim 5, wherein the medium electrode selection unit in the medium-side voltage control step is a display primary color of a color display of the recording medium. It has a structure that is a color unit.

With this configuration, in addition to the operation of the fifth aspect, the following operation is provided.

(1) Since the selection unit of the counter electrode in the medium side voltage control process is the color unit of the display primary color of the color display of the recording medium, the image information can be divided into color units and an image can be formed. It is possible to reliably prevent color misregistration and obtain a high-quality color image.

[0026] Here, by forming the counter electrode in a strip shape corresponding to each display primary color arranged in a striped pattern, the counter electrode can be easily selected in color units. Since the counter electrode can form an image in the color unit of the display primary color of the color display, the mounting density of the discharge electrode of the heat discharge type print head is coarser than the resolution of the subpixels of the recording medium! High-quality color images can be formed.

[0027] The invention described in claim 7 is the image forming method according to any one of claims 1 to 6, wherein the recording medium is initialized as a pre-process of the potential difference setting process. It has a structure equipped with a crystallization process.

With this configuration, in addition to the operation of any one of claims 1 to 6, the following operation is provided.

(1) By having an initialization step of initializing the recording medium as a pre-step of the potential difference setting step, an image can be formed after the display layer of the recording medium is reliably initialized before image formation. Excellent image quality reliability.

(2) When the potential difference setting process, discharge electrode heating process, softening process or curing process is repeated for each color of the display primary color of the recording medium, an initialization process is performed as a pre-process of the potential difference setting process. Can erase unnecessary display images and prevent color misregistration. It can be reliably prevented and the image quality is highly reliable.

Here, when the recording medium uses an image display material containing a dispersion medium that is softened by thermal energy, the initialization process is a pre-process of the potential difference setting process and a post-process of the softening process. This is because the image on the display layer of the recording medium cannot be erased after the dispersion medium has been softened.

In addition, when the recording medium uses an image display material in which a dispersion medium that is cured by thermal energy is used, the initialization process is a pre-process of the potential difference setting process. This is because the image on the display layer of the recording medium can be erased before the dispersion medium is cured.

[0029] An image forming apparatus according to claim 8 of the present invention is a display layer using an electrophoretic image display material in which colored particles are dispersed in a dispersion medium that is softened or hardened by thermal energy. An image forming apparatus for forming an image on a recording medium having a heating discharge type print head comprising a discharge electrode having an electron emission site and a heating means for selectively heating the discharge electrode, and the discharge electrode And a counter electrode formed on the surface opposite to the recording surface of the recording medium, the recording surface of which is arranged to face the heating and discharge type print head, and set a potential difference corresponding to a discharge control voltage. It has a configuration including a potential difference setting unit that forms an electric field and a recording medium heating unit that heats the recording medium to soften or harden the dispersion medium.

This configuration has the following effects.

(1) The potential difference setting unit sets a potential difference corresponding to the discharge control voltage between the discharge electrode and the counter electrode to prepare for the discharge in a state where an electric field is formed, and the discharge control voltage becomes a high voltage. By selectively heating the discharge electrode with a heating means that does not require direct control of the discharge, a discharge can be generated between the discharge electrode and the counter electrode, and the electrons and ions emitted by the discharge electrode as much as possible by the electric field can be generated. The image can be displayed by moving to the recording medium side and applying a charge to the recording surface.

(2) By having a potential difference setting part that forms an electric field by setting a potential difference corresponding to the discharge control voltage between the discharge electrode and the counter electrode, a part of the discharge control voltage is provided on the counter electrode side in the potential difference setting part. Can be applied selectively, reducing the voltage directly applied to the discharge electrode of the heat-discharge-type print head, and can efficiently generate discharge to save energy. Excellent ruggedness.

(3) Since the potential difference setting unit can arbitrarily set the voltage value applied to each of the discharge electrode and the counter electrode so that the potential difference between the discharge electrode and the counter electrode becomes equal to the discharge control voltage. The voltage applied to the counter electrode can be optimally adjusted according to the type and characteristics of the recording medium, and the versatility is excellent.

(4) By heating the recording medium in the recording medium heating section, the dispersion medium contained in the image display material of the display layer can be softened or cured, and the dispersion medium is softened to form an image and cooling. By curing the dispersion medium or forming an image and then heating to disperse the dispersion medium, the image formed on the recording medium is fixed and an image with excellent durability without change over time is obtained. Can be formed.

[0030] Here, the discharge control voltage, the discharge electrode, and the electrophoretic image display material are the same as those described in claim 1 or 2, and thus the description thereof is omitted.

In this image forming apparatus, an electric field is formed by setting a potential difference corresponding to the discharge control voltage between the discharge electrode and the counter electrode in the potential difference setting unit, and heating the discharge electrode by the heating unit. Since the generation of electric discharge can be controlled, it is possible to easily generate an electric discharge by selectively discharging an electron from the vicinity of an arbitrary heating position (electron emission site) of the discharge electrode by selecting a heating position by the heating means. .

[0032] As a heating means for heating the discharge electrode, a laser beam irradiation unit, an infrared irradiation unit, or the like, a method of irradiating laser light, infrared rays, or the like is preferably used. As a method for irradiating laser light, the same laser scanner unit as in the conventional electrophotographic method can be used, and the laser irradiation unit is combined with a polygon mirror or a galvanometer mirror to scan only the laser light with respect to the discharge electrode. For example, a laser irradiation unit that scans the laser irradiation portion with respect to the discharge electrode is preferably used. In addition, laser light or infrared light may be condensed with an optical fiber or a condensing lens and irradiated to the discharge electrode. In particular, when an optical fiber array in which a large number of optical fibers are arranged with high density and high accuracy is used, a plurality of electron emission sites can be simultaneously irradiated with laser light and infrared rays at high speed. Recording is possible and productivity is excellent.

In addition, a thermal print head used in a conventional thermal facsimile as a heating means. A structure similar to that of the discharge electrode can be used in close contact with the discharge electrode protective layer. Specifically, the heat generation of the heating resistor is controlled by a driver IC that is electrically connected to the heating resistor.

[0033] As the recording medium heating section, a heater that is heated in a surface contact with the recording medium with a heater formed in a surface shape or a roll shape is preferably used. It should be noted that a heater may be incorporated in a restoring device such as a charging roller or the like that initializes the recording medium, or a conveyance roller, and used as a recording medium heating unit.

Note that the recording medium heating section preferably includes a temperature adjusting means so that the recording medium heating section can be heated at different temperatures corresponding to the display primary colors. This is because the mounting density of the discharge electrodes of the heat-discharge type print head is coarser than the resolution of the subpixels of the recording medium, or the counter electrode is one of a common rectangular shape or square shape over the entire surface of the display medium. If the image is formed by dividing the image information into color units at the time of image formation, the electrons and ions emitted from the electron emission site force of the discharge electrode Irradiates a wider area than the pixel. As a result, an image in a state where color misregistration occurs due to charging up to an area displaying different display primary colors adjacent to each other is formed. Therefore, by using a recording medium heating unit equipped with a temperature adjusting means, heating the dispersion medium at a temperature higher than the softening temperature or curing temperature corresponding to the display primary color to be displayed, the dispersion of the image display material corresponding to that color is achieved. Only a medium can be selectively softened or cured to rewrite or fix a monochrome image. This is because the other portions can be re-initialized, so that the image information can be reliably divided into color units to form an image, and a high-quality color image can be obtained. In addition, even when a plurality of image display materials that display different display primary colors are arranged in one pixel, the dispersion medium contained in the image display material can be selectively softened in units of display primary colors. Since the image can be rewritten and fixed after being cured, the image information can be reliably divided into color units to form an image, and a high-quality color image can be obtained without causing color misregistration. Because it can.

[0034] The invention according to claim 9 is the image forming apparatus according to claim 8, wherein the image forming apparatus includes a restorer that initializes the recording medium.

With this configuration, in addition to the operation of the eighth aspect, the following operation is provided. (1) Even if an unnecessary image is formed on the display layer in the storage state or in the operation of attaching / detaching the recording medium, the image is formed after the display layer of the recording medium is initialized by the decompressor. The image quality is highly reliable.

Here, the restorer can be appropriately selected according to the type of the recording medium. If the recording medium is capable of erasing an image by charging, initialization can be performed by uniformly charging the display layer with a charging roller or a charging brush. For example, if the white colored particles are electrophoretic particles having a negative charge, the white colored particles are moved to the display surface side of the recording medium by charging the display surface side of the recording medium with a positive charge. The display layer can be made blank. If the colored particles colored in the display primary color are electrophoretic particles having a positive charge, the colored particles of the display primary color are displayed by charging the surface opposite to the display surface of the recording medium with a negative charge. The display layer can be blanked by moving it to the opposite side.

If the recording medium is initialized by heat or magnetism, a heat roller or a magnet roller can be suitably used as the restoring device.

[0035] The invention according to claim 10 is the image forming apparatus according to claim 8 or 9, wherein the potential difference setting unit includes a head side voltage applying unit that applies a voltage to the discharge electrode, and an image information. And a medium side voltage control unit for selectively grounding or applying a voltage to the counter electrode based on the information.

With this configuration, the following actions are taken in addition to the actions of the eighth or ninth aspect.

(1) The potential difference setting unit includes a head-side voltage application unit that applies a voltage to the discharge electrode and a medium-side voltage control unit that selectively performs grounding or voltage application to the counter electrode based on image information. Since the discharge control voltage can be distributed and applied to the discharge electrode and the counter electrode, the voltage value applied to the counter electrode can be adjusted according to the type and characteristics of the recording medium. Can reduce the burden and efficiently generate discharge

Here, the head-side voltage application unit only needs to apply a preset voltage to the entire discharge electrode, and does not need to control the high voltage. The medium side voltage control unit selectively grounds or applies voltage to the counter electrode formed on the surface opposite to the recording surface of the recording medium. Even when applying voltage, by setting the applied voltage low, it is possible to obtain a high-quality image by arranging the counter electrodes at high density, and to use a driver IC that supports low withstand voltage, Easy to control and easy to handle.

The invention's effect

[0037] As described above, according to the image forming method and the image forming apparatus of the present invention, the following advantageous effects can be obtained.

According to the invention described in claim 1, the following effects are obtained.

(1) When the recording medium is heated by the softening process, the image can be rewritten. In the potential setting process, an electric field is formed by setting a potential difference corresponding to the discharge control voltage between the discharge electrode and the counter electrode. In the discharge electrode heating process, it is possible to form an image by generating a discharge simply by selectively heating the discharge electrode based on the image information. The image formed on the recording medium is cooled by the recording medium. It can be fixed, and it is difficult to be affected by changes in the environment and static electricity. An excellent image forming method can be provided.

[0038] According to the invention of claim 2, the following effects are obtained.

(1) In the potential difference setting process, a potential difference corresponding to the discharge control voltage is set between the discharge electrode and the counter electrode to form an electric field, and in the discharge electrode heating process, the discharge electrode is selected based on image information! It is possible to form an image by generating electric discharge only by heating it, and fixing the image formed on the recording medium by heating the recording medium by the curing process. Thus, it is possible to provide an image forming method excellent in productivity and reliability, capable of easily forming an image excellent in stability of image quality that does not easily change over time and is not easily affected by the above.

[0039] According to the invention of claim 3, in addition to the effect of claim 1 or 2, the following effect is obtained.

(1) During the potential difference setting process, the voltage is applied to the entire discharge electrode in the head-side voltage application process, and the discharge is performed by grounding or applying a voltage to the counter electrode in the medium-side voltage control process. A potential difference corresponding to the discharge control voltage is selectively generated between the electrode and the counter electrode. Thus, it is possible to provide an image forming method that can easily control the voltage that can be prepared for the discharge and is excellent in productivity.

[0040] According to the invention of claim 4, in addition to the effect of any one of claims 1 to 3, it has the following effects.

(1) The potential difference setting process, discharge electrode heating process, softening process or curing process is repeated for each color of the display primary color of the recording medium to form an image by dividing the image information into color units. It is possible to prevent the occurrence of color misregistration and to fix the formed image to obtain a high-quality and reliable color image that does not change with time. An excellent image forming method can be provided.

(2) Each time an image in color units is formed in the discharge electrode heating process, it is formed in color units by heating the recording medium at a different temperature corresponding to the display primary color as a subsequent process or a previous process. It is possible to provide an image forming method that can perform image rewriting and fixing in sequence, can easily prevent color misregistration, and can be easily controlled and has excellent reliability.

[0041] According to the invention of claim 5, in addition to the effect of any one of claims 1 to 3, it has the following effects.

(1) By performing the medium-side voltage control process in synchronization with the discharge electrode heating process, an image forming method with excellent control reliability and high image quality that can prevent discharge due to malfunction. Can be provided.

[0042] According to the invention described in claim 6, in addition to the effect of claim 5, the following effect is obtained.

(1) In the medium-side voltage control process, image information is divided into color units and images are formed by selecting the presence or absence of grounding or voltage application to the counter electrode in units of color for the display primary color of the recording medium. Therefore, it is possible to provide an image forming method that can easily prevent color misregistration and obtain a high-quality color image and that is easy to control and excellent in image quality.

[0043] According to the invention described in claim 7, in addition to the effect of any one of claims 1 to 6, the following effects are obtained. (1) When the potential difference setting process, discharge electrode heating process, softening process or curing process is repeated for each color of the display primary color of the recording medium, an initialization process is performed as a pre-process of the potential difference setting process. Accordingly, it is possible to provide an image forming method excellent in image quality reliability in which an unnecessary display image can be blanked and color misregistration can be reliably prevented.

[0044] According to the invention of claim 8, the following effects are obtained.

(1) By simply heating the recording medium with the recording medium heating section, the image can be easily rewritten and fixed, and an image having excellent durability without change over time is formed on the recording medium. Therefore, it is possible to provide an image forming apparatus with excellent image quality reliability.

[0045] According to the invention described in claim 9, in addition to the effect of claim 8, the following effect is obtained.

(1) Even if an unnecessary display image is formed on the display layer in the process of storage and handling of the recording medium, it can be erased reliably by the decompressor, and a high-quality image can be formed. An image forming apparatus with excellent reliability that can be provided can be provided.

[0046] According to the invention of claim 10, in addition to the effect of claim 8 or 9, it has the following effect.

(1) Since the discharge control voltage can be distributed and applied to the discharge electrode and the counter electrode by the head side voltage application unit and the medium side voltage control unit of the potential difference setting unit, depending on the type of recording medium, etc. Thus, it is possible to provide a versatile image forming apparatus capable of adjusting the voltage value applied to the counter electrode, reducing the burden on the discharge electrode side, and efficiently generating discharge.

Brief Description of Drawings

[0047] [FIG. 1] A schematic diagram of a main part showing a configuration of an image forming apparatus according to the first embodiment.

[FIG. 2] (a) Schematic cross-sectional view of the main part showing the heat-discharge type print head and the recording medium of the image forming apparatus in Embodiment 1. (C) Enlarged schematic view of part A in Fig. 2 (a)

FIG. 3 is a schematic fragmentary view showing an image forming method using the image forming apparatus in Embodiment 1. Area

FIG. 4 is a schematic cross-sectional view of an essential part showing an initialization process of an image forming method using the image forming apparatus in Embodiment 1.

FIG. 5 is a schematic diagram showing a main part of a configuration of an image forming apparatus according to Embodiment 2.

FIG. 6 is a schematic cross-sectional view of a main part showing a heat-discharge type print head and a recording medium of the image forming apparatus in Embodiment 2.

[Fig.7] Enlarged schematic diagram of part B in Fig.5

FIG. 8 is a schematic cross-sectional view of an essential part showing a curing step of an image forming method according to a modification of the second embodiment.

1, la Image forming device

2 Heating discharge type print head

3 Restorer

3a, 4a, 4c, 5c Recording medium heating section

4 Cooling unit

5a, 5b Transport roller

10 Board

11 Heating means

11a Heating resistor

l ib driver IC

12 Insulating film

13 Discharge electrode

13a Electron emission site

14 Potential difference setting section

15 Head side voltage application section

16, 16a Medium side voltage controller

20, 30 Recording medium

20a, 30a Recording surface 22, 32 Counter electrode

23 Display layer

23a Surface substrate

24 Micro Capsenore

24a Colored particles

24b, 24c, 24d colored particles

24e, 24f Dispersion medium

32a color separation electrode

32b color selection electrode

BEST MODE FOR CARRYING OUT THE INVENTION

[0049] (Embodiment 1)

An image forming apparatus and an image forming method using the same according to Embodiment 1 of the present invention will be described below with reference to the drawings.

FIG. 1 is a main part schematic diagram showing the configuration of the image forming apparatus according to the first embodiment. In FIG. 1, 1 is an image forming apparatus according to Embodiment 1 of the present invention, 2 is a heat-discharge type print head of the image forming apparatus 1, 3 is a restoring device using a charging roller for initializing the recording medium 20, and 3a is A recording medium heating unit that is built in the restorer 3 and also has a heater power for heating the outer peripheral surface of the restorer 3 to a predetermined temperature, 4 is a cooling unit such as a cooling nozzle that jets cold air that cools the heated recording medium 20, 5a and 5b are respectively opposed to the heat-discharge type print head 2 and the restoring unit 3 and are transport rollers for transporting the recording medium 20, and 5c is built in the transport roller 5a to heat the outer peripheral surface of the transport roller 5a to a predetermined temperature. It is a recording medium heating unit that also has a heater force.

Next, details of the heat-discharge type print head and the recording medium of the image forming apparatus according to Embodiment 1 will be described.

FIG. 2 (a) is a schematic cross-sectional view of the main part showing the heat discharge type print head and the recording medium of the image forming apparatus in Embodiment 1, and FIG. 2 (b) is an AA of the heat discharge type print head of (a). — A cross-sectional view of the main part taken along line AA, and FIG. 2 (c) is an enlarged schematic view of part A of FIG. 2 (a) and 2 (b), 10 is a substrate on which heating means 11 and discharge electrodes 13 which will be described later are laminated, and 11 is a heat discharge type print which selectively heats the discharge electrodes 13 which will be described later. Heating means for head 2, 11a is a heating resistor of heating means 11 arranged in a matrix on substrate 10 at a predetermined pitch, 1 lb is electrically connected to each heating resistor 1 la and controls its heat generation Driver IC of the heating means 11 to be operated, 12 is an insulating film which is covered with the heating resistor 1 la and insulates the heating means 11 and the discharge electrode 13 which will be described later, 13 is a heating discharge type formed in a substantially rectangular flat plate shape The discharge electrode of the print head 2, 13 a is an electron emission site of the discharge electrode 13 from which electrons are emitted by being heated by the heating resistor 11 a, 14 is the recording surface 20 a on the discharge electrode 13 and the heat discharge type print head 2 A potential difference setting unit 15 that sets an electric potential difference corresponding to a discharge control voltage between the recording surface 20a of the recording medium 20 disposed opposite to the opposing electrode 22 formed on the opposite surface, and forms an electric field. Applying head side voltage to potential difference setting unit 14 that applies voltage to discharge electrode 13 , 16 is a medium-side voltage control unit of the potential difference setting unit 14 that selectively applies a voltage to the counter electrode 22 based on image information, and 20 is charged by being charged by the heat-discharge type print head 2. 20a is a recording surface of the recording medium 20 to which an electric charge is applied, 21 is a substrate of the recording medium 20, and 22 is formed in a substantially rectangular shape over almost the entire surface of the substrate 21. The flat counter electrode 23 of the recording medium 20 is a display layer of the recording medium 20 having an electrophoretic image display material.

In the present embodiment, the counter electrode 22 is made of a metal having a high thermal conductivity such as aluminum or copper. This is to increase temperature sensitivity.

In FIGS. 2 (a) and 2 (b), for convenience of explanation, the electrode for energizing the heating resistor 11a is omitted.

Next, details of the display layer of the recording medium will be described.

In FIG. 2 (c), 23a is a surface substrate covered on the upper surface of the display layer 23, 24 is a microcapsule of image display material sealed in the display layer 23, 24a is negatively charged and microcapsule 24 White colored particles encapsulated in, 24b positively charged and Y colored particles encapsulated in microcapsule 24, 24c positively charged and M colored particles encapsulated in microcapsule 24, 24d is a positively charged C colored particle encapsulated in the microcapsule 24, and 24e is a dispersion medium that is encapsulated in the microcapsule 24 and softens when heated.

In Fig. 2 (c), the area separated by the dotted line in the display layer 23 of the recording medium 20 It corresponds to the element. Each pixel is composed of three sub-pixels, and each sub-pixel has white colored particles 24a and colored particles of any one of the three primary colors (Y, M, C) in the subtractive color mixing method that is the display primary color for color display. Microcapsules 24 in which 24b, 24c, and 24d are enclosed are arranged for each color.

The microcapsules 24 with different display primary colors in which the colored particles 24b, 24c, and 24d are encapsulated are mixed with waxes having different melting points and have different softening temperatures (temperatures at which the colored particles can be electrophoresed). 24e is used. For the convenience of explanation, in the present embodiment, the softening temperature of the dispersion medium 24e in which the colored particles 24b are dispersed is α, the softening temperature of the dispersion medium 24e in which the colored particles 24c are dispersed is j8, and the colored particles. The softening temperature of the dispersion medium 24e in which 24d is dispersed is γ (γ (| 8 く α).

An image forming method will be described based on the operation of the image forming apparatus configured as described above.

FIG. 3 is a schematic cross-sectional view showing the main part of the image forming method using the image forming apparatus in the first embodiment, and FIG. 4 shows the initialization process of the image forming method using the image forming apparatus in the first embodiment. It is a principal part schematic sectional drawing shown.

First, when the recording medium 20 is not blank, the outer surface of the restorer 3 is heated to a temperature higher than oc by the recording medium heating unit 3a, and then the outer surface of the restorer 3 is brought into close contact with the recording medium 20 Thus, the temperature of the dispersion medium 24e of the recording medium 20 is higher than oc and is heated to a temperature to soften the dispersion medium 24e (softening process). Almost simultaneously with this, in the initialization process, the recording medium 20 is uniformly charged to a positive polarity opposite to that during image formation (see FIG. 1). Since the dispersion medium 24e is the highest and is heated to a temperature higher than the softening temperature α, the white colored particles 24a having a negative charge in all the microcapsules 24 move to the recording surface 20a side, and the recording medium 2 Erase the image on display layer 23 of 0 and display a blank page.

Next, as shown in FIG. 2 (a), the potential difference setting step is performed while the recording medium 20 is being conveyed by the conveyance port roller 5a heated by the recording medium heating unit 5c so that the outer surface has a temperature higher than α. During the head side voltage application step, a voltage lower than the discharge control voltage is applied to the discharge electrode 13 of the heating / discharge type print head 2 by the head side voltage application unit 15 of the potential difference setting unit 14. In the medium side voltage control step of the potential difference setting step, the medium of the potential difference setting unit 14 The side voltage control unit 16 applies the remaining voltage to the counter electrode 22 of the recording medium 20 so that the potential difference between the discharge electrode 13 and the counter electrode 22 becomes equal to the discharge control voltage.

Subsequently, in the discharge electrode heating step, for example, when recording in Y color on the leftmost pixel of the three pixels in FIG. 2A, the heating resistor located at the position corresponding to the leftmost pixel 11a generates heat and the discharge electrode 13 is selectively heated. As a result, electrons are emitted from the electron emission site 13a of the discharge electrode 13 heated by the heating resistor 11a, and a discharge is generated. The entire leftmost pixel selected in the recording surface 20a of the recording medium 20 is irradiated with electrons and ions generated by the discharge.

At this stage, as shown in Fig. 2 (c), positively charged colored particles 24b, 24c, and 24d are formed on the recording surface 20a by the three microcapsules 24 in the pixel irradiated with electrons and ions. The display primary colors (Y, M, C) forces S are displayed. Of the discharge electrode 13, when heated by the heating resistor 1 la, no electrons are emitted from the portion of the electron emission portion 13 a and no discharge is generated, so that other pixels remain in white display. .

Next, the recording medium 20 is moved to the cooling unit 4 (see FIG. 1) side, and as shown in FIG. 3, the dispersion medium 24e of the recording medium 20 is cooled to a temperature lower than γ by blowing cold air. Thereby, all the dispersion medium 24e enclosed in the microphone mouth capsule 24 is thickened or hardened.

Next, after the outer surfaces of the restorer 3 and the transport roller 5a are heated to a temperature of ~ β by the recording medium heating units 3a and 5a, the recording medium 20 is moved to the restorer 3, and the restorer 3 and the transport roller 5a When the outer surface is brought into close contact with the recording medium 20, the temperature of the dispersion medium 24e of the recording medium 20 is heated by α to β to disperse the microcapsule 24 having the amber and C colored particles 24c and 24d. The medium 24e is softened (softening process). The Y colored particles 24b cannot move in the microcapsules 24 because the softening temperature a of the dispersion medium 24e is higher than the heating temperature j8 and does not soften, and the Y color image is fixed.

Next, returning to the initialization step, as shown in FIG. 4, the restorer 3 uniformly charges the recording medium 20 with a positive polarity opposite to that at the time of image formation. As a result, in the microcapsule 24 including the M and C colored particles 24c and 24d in the pixel, the white colored particles 24a having a negative charge move to the recording surface 20a side, and recording by the Y color is performed. Only the image is displayed and can be prepared for a subsequent M or C color record. In the case of forming an M-color image, similarly, the recording medium 20 is charged with the heating and discharging type print head 2, and then the outer surfaces of the restoring device 3 and the conveying roller 5a are set to β˜ with the recording medium heating units 3a and 5a. Then, the recording medium 20 is moved to the restorer 3 and the outer surfaces of the restorer 3 and the transfer port roller 5a are brought into close contact with the recording medium 20, thereby dispersing the dispersion medium 24e of the recording medium 20e. Is heated to γ to soften the dispersion medium 24e of the microcapsule 24 having the C colored particles 24d (softening step). The colored particles 24b and 24c of Y color and M color cannot move in the microcapsule 24 because the softening temperatures α and β of the dispersion medium 24e are higher than the heating temperature γ and cannot move inside the microcapsule 24. The color image is fixed.

When forming a C-color image, the process returns to the initialization step, and the restorer 3 uniformly charges the recording medium 20 with a positive polarity opposite to that at the time of image formation. As a result, in the microcapsule 24 including the C colored particles 24d in the pixel on the left end, the white colored particles 24a having a negative charge move to the recording surface 20a side to be initialized, and similarly, heat discharge is performed. An image can be formed by charging the recording medium 20 with the mold printing head 2.

As described above, a color image without color misregistration can be formed by repeating the softening step, the initialization step, the potential difference setting step, and the discharge electrode heating step in units of display primary colors (Y, M, C). it can.

In the present embodiment, in the head side voltage application step, a voltage corresponding to the discharge control voltage is distributed and applied to the discharge electrode 13 and the counter electrode 22 of the recording medium 20. In the head side voltage application step, the discharge control voltage is applied. It is also possible to apply all of the voltage corresponding to to only the discharge electrode 13 and ground the counter electrode 22 of the recording medium 20 in the medium-side voltage control step. Note that either the head side voltage application step or the medium side voltage control step in the potential difference setting step may be performed first.

Further, instead of using the recording medium 20 in which the counter electrode 22 is formed on the surface opposite to the recording surface 20a, a similar counter electrode 22 is provided on the image forming apparatus 1 side, and the recording medium 20 on the side opposite to the recording surface 20a is provided. You may make it contact or adjoin to a surface. In this case, it is preferable to place the recording medium 20 on the flat plate-like recording medium placing portion instead of the transport rollers 5a and 5b and horizontally move the recording medium placing portion. By forming the charge control electrode on the surface of the recording medium mounting portion, the back surface of the recording medium 20 and the charge control electrode can be reliably brought into contact with each other. It is.

In addition, although the case of the cooling nozzle that injects cold air as the cooling unit 4 has been described, the cooling unit 4 may be cooled by being brought into close contact with a roller made of copper or the like having a high thermal conductivity. Further, the cooling unit 4 may be allowed to cool naturally without being forced to cool.

Further, although the case where a charging roller is used as the restoring device 3 has been described, a charging brush or the like may be used instead of the charging roller. In this case, a recording medium heating unit such as a roller is provided upstream of the restorer 3.

[0056] In the present embodiment, the force using the recording medium 20 having the display layer 23 in which the colored particles 24a to 24d and the dispersion medium 24e are enclosed in the microcapsule 24 is not limited to this. 23 may be any material that uses an electrophoretic image display material. For example, the colored particles 24 a to 24 d and the dispersion medium 24 e may be enclosed in a space partitioned by a partition wall or the like instead of the microcapsule 24.

In the present embodiment, as shown in FIGS. 2 to 4, the microcapsules 24 in which the colored particles 24b, 24c, and 24d colored in the three primary colors (Y, M, and C) are encapsulated are repeated. However, the arrangement of the colors for each pixel may be random. In the image forming method of the present embodiment, the image display material in the pixel can be selectively electrophoresed by the softening process, and then the image is formed by the discharge electrode heating process in units of pixels. This is because there is no difference in the displayed image regardless of which display primary color is arranged at which position in the pixel.

Since the image forming apparatus according to Embodiment 1 is configured as described above, it has the following operations.

(1) The potential difference setting unit 14 can set up a potential difference corresponding to the discharge control voltage between the discharge electrode 13 and the counter electrode 22 to prepare for the discharge in a state where an electric field is formed. By selectively heating the discharge electrode 13 with the heating means 11 that does not require direct control of the control voltage, a discharge can be generated between the discharge electrode 13 and the counter electrode 22, and it is emitted from the discharge electrode 13 by an electric field. An image can be formed by transferring the charged electrons and ions to the recording medium 20 side, applying a charge to the recording surface 20a, and charging the recording surface 20a.

(2) A potential difference corresponding to the discharge control voltage is set between the discharge electrode 13 and the counter electrode 22. By having the potential difference setting unit 14 that forms an electric field, the potential difference setting unit 14 can selectively apply a part of the discharge control voltage to the counter electrode 22 side, so that the discharge electrode of the heat discharge type print head 2 can be applied. The voltage directly applied to 13 can be reduced, and discharge can be generated efficiently, resulting in excellent energy savings.

(3) The potential difference setting unit 14 arbitrarily sets the voltage value applied to each of the discharge electrode 13 and the counter electrode 22 so that the potential difference between the discharge electrode 13 and the counter electrode 22 becomes equal to the discharge control voltage. Therefore, the voltage value applied to the counter electrode 22 can be optimally adjusted according to the type and characteristics of the recording medium 20, and the versatility is excellent.

(4) The recording medium 20 is heated to a temperature higher than the softening temperature of the dispersion medium 24e by the recording medium heating units 3a and 5c, thereby softening the dispersion medium 24e contained in the microcapsules 24 of the display layer 23. Therefore, after the recording medium 20 has been cooled, the image formed on the recording medium 20 can be fixed as long as it is not heated above its soft temperature.

Thus, an image having excellent durability can be formed without change over time.

(5) By charging the recording medium 20 with the electric charge having the opposite polarity to that at the time of image formation by the restorer 3, the white colored particles 24a can be moved to the display surface 20a side of the recording medium 20, and the recording The display layer 23 of the medium 20 can be initialized with a blank page.

(6) By adjusting the heating temperature of the recording medium 20 by the recording medium heating units 3a and 5c for each softening temperature of the dispersion medium 24e, a plurality of micro power cells 24 that display different display primaries in one pixel can be obtained. Even if it is placed, the dispersion medium 24e enclosed in the microcapsule 24 is selectively softened in units of display primary colors so that it can be partially rewritten, and the image is selectively fixed. Therefore, it is possible to reliably divide the image information into color units and form an image, and it is possible to obtain a high-quality color image without causing color misregistration.

(7) By heating the recording medium 20 to a higher temperature (γ to j8, β to α) than the softening temperature (γ, β) of the dispersion medium 24e by the recording medium heating units 3a and 5c, the color of the display primary color of the color display Since the image can be rewritten and fixed in units (sub-pixel units), even if the mounting density of the discharge electrodes 13 of the heat-discharge type print head 2 is coarser than the resolution of the sub-pixels of the recording medium 20, high-quality color An image can be formed. Since the image forming method of Embodiment 1 is configured as described above, it has the following operations.

(1) In the potential difference setting process, a potential difference corresponding to the discharge control voltage is set between the discharge electrode 13 and the counter electrode 22 to form an electric field. Since the discharge can be generated only by selectively heating the discharge electrode 13 based on the information, it is not necessary to control the high voltage, and the recording medium 20 can be easily charged by charging the recording medium 20 to control the generation of the discharge. Can be formed.

(2) The potential difference setting step is electrically connected to the counter electrode 22 and the head side voltage applying step of applying a voltage to the discharge electrode 13 by the head side voltage applying unit 15 electrically connected to the discharge electrode 13. Medium-side voltage control step of applying a voltage to the counter electrode 22 by the medium-side voltage control unit 16, so that a voltage is applied to the entire discharge electrode 14 in the head-side voltage application step, and the medium-side voltage control step To! Then, by applying a voltage to the counter electrode 22, a potential difference corresponding to the discharge control voltage can be selectively generated between the discharge electrode 13 and the counter electrode 22 to prepare for the discharge.

(3) By repeating the potential difference setting process, the discharge electrode heating process, and the softening process for each color of the display primary color of the recording medium 20, the image information can be divided into color units to form an image. In addition to preventing the occurrence of color misregistration, the formed image can be fixed to obtain a high-quality and reliable color image that does not change with time.

(4) Since the recording medium 20 can be heated at a different temperature corresponding to the primary color of the display by the softening process, every time an image in color units is formed in the discharge electrode heating process, the softening process is performed as a preceding process. By performing the color step, it is possible to partially and partially rewrite images formed in units of colors, and to effectively prevent color misregistration.

(5) Since the medium-side voltage control step can be performed in synchronization with the discharge electrode heating step, it is possible to prevent the occurrence of discharge due to a malfunction, and it is excellent in control reliability and image quality.

(6) By having an initialization step of applying a charge of the opposite polarity to the charge used for recording on the recording surface 20a of the recording medium 20 as a previous step of the potential difference setting step, the display of the recording medium 20 can be reliably performed before image formation. Layer 23 can be initialized with a blank sheet, which provides excellent image quality reliability. It is.

(7) When the potential difference setting process, discharge electrode heating process, and softening process are repeated for each color of the display primary color of the recording medium 20, initialization is performed as a subsequent process of the softening process and a previous process of the potential difference setting process. By performing the process, unnecessary display images can be made blank, and color misregistration can be reliably prevented, and the image quality is highly reliable.

(Embodiment 2)

An image forming apparatus and an image forming method using the same according to Embodiment 2 of the present invention will be described below with reference to the drawings.

FIG. 5 is a main part schematic diagram showing the configuration of the image forming apparatus in the second embodiment, and FIG. 6 is a main part schematic sectional view showing the heat-discharge type print head and the recording medium of the image forming apparatus in the second embodiment. FIG. 7 is an enlarged schematic view of the B part of FIG. In addition, the same code | symbol is attached | subjected to the thing similar to Embodiment 1, and description is abbreviate | omitted.

In FIG. 5, la is an image forming apparatus according to Embodiment 2 of the present invention, and 4a is a recording medium heating unit that heats the recording medium 30 in close contact with the substrate 21 and the display layer 23a of the recording medium 30.

In FIG. 6, the image forming apparatus la in the second embodiment is different from the first embodiment in that all voltages corresponding to the discharge control voltage are heated and discharged by the head side voltage applying unit 15 of the potential difference setting unit 14. This is applied only to the discharge electrode 13 of the head 2 and selectively grounded to the counter electrode 32 of the recording medium 30 by the medium side voltage control unit 16a of the potential difference setting unit 14.

In addition, the recording medium 30 used in the image forming apparatus la in the second embodiment is different from the recording medium 20 used in the first embodiment in that the counter electrode 32 is a display primary color (Y, The color-dividing electrode 32a is divided into colors corresponding to the arrangement of the respective colors (M, C) and formed in a striped pattern, and the color-selecting electrode 32b that connects the color-dividing electrodes 32a of the same color is provided. It is. In addition, the dispersion medium 24f encapsulated in the microcapsule 24 has a low viscosity at normal temperature, so that the colored particles can be electrophoresed. Dispersion medium such as thermosetting resin such as polyisocyanate type and epoxy type that hardens when heated. It is a point using. For convenience of explanation, in this embodiment, the curing temperature of the dispersion medium 24f in which the colored particles 24b are dispersed (coloring L is the temperature at which particle electrophoresis is impossible), m is the curing temperature of dispersion medium 24f in which colored particles 24c are dispersed, and n is the curing temperature of dispersion medium 24f in which colored particles 24d are dispersed (L <m < n).

First, when the recording medium 30 is not blank, in the initialization process, the restoring medium 3 uniformly charges the recording medium 30 with a positive polarity opposite to that at the time of image formation, as in the first embodiment (see FIG. 1). As a result, in all the microcapsules 24, the white colored particles 24a having a negative charge move to the recording surface 30a side, and the display layer 23 of the recording medium 30 is blanked to erase the image.

Next, as shown in FIG. 6, in the head side voltage application step of the potential difference setting step, the head side voltage application unit 15 of the potential difference setting unit 14 corresponds to the discharge control voltage to the discharge electrode 13 of the heat discharge type print head 2. Apply the voltage.

Further, in the medium side voltage control step of the potential difference setting step, the same color separation electrode 32a connected by the color selection electrode 32b of the counter electrode 32 is grounded simultaneously by the medium side voltage control unit 16a of the potential difference setting unit 14 (FIG. 6). Then select Y).

[0061] Subsequently, in the discharge electrode heating process, for example, when recording in Y color on the leftmost pixel of the three pixels in FIG. 6, the heating resistor 1 la located at the position corresponding to the leftmost pixel is performed. And the left end of the discharge electrode 13 is selectively heated. At this time, only the color-dividing electrode 32a corresponding to the selected Y color is grounded, so that it corresponds to the electron emission site 13a at the left end of the discharge electrode 13 heated by the heating resistor 1 la and the Y color. Discharge occurs only between the leftmost color segmentation electrode 32a, and no discharge occurs between the color segmentation electrode 32a and discharge electrode 13 corresponding to M and C colors that are not grounded. As a result, the position of the sub-pixel on the leftmost Y color is charged by the action of charges of electrons and ions generated by the discharge, but it is not charged on the M and C colors. In addition, no discharge occurs between a portion of the discharge electrode 13 that is not heated by the heating resistor 11a and the color division electrode 32a facing the portion. Since the counter electrode 32 is formed so as to be selectable in units of colors, color misregistration does not occur at the stage of forming an image in the discharge electrode heating process. Next, in the curing process, the recording medium 30 is heated by the recording medium heating unit 4a in which the temperature of the outer surface is set to L to m, and the dispersion medium 24f in which the colored particles 24b are dispersed is cured so that the colored particles 24b are obtained. Fix it.

Next, the potential difference setting step and the discharge electrode heating step are performed for the M color, and the recording medium 30 is heated at a temperature of m to n throughout the curing step, and the dispersion medium 24f in which the colored particles 24c are dispersed is cured to form the colored particles. Fix 24c. Finally, in the same way for the C color, as shown in FIG. 7, it is possible to cure all the dispersion media 24f and fix the colored particles 24a, 24b, 24c, 24d to form a color image.

FIG. 8 is a schematic cross-sectional view of the relevant part showing the curing step of the image forming method of the modification of the second embodiment.

In the second embodiment, the case where the potential difference setting step, the discharge electrode heating step, and the curing step are repeatedly performed has been described. However, the potential difference setting step and the discharge electrode heating step are repeatedly performed to form an arbitrary color image. After that, as shown in FIG. 8, in the curing process, the recording medium 30 is heated by the recording medium heating unit 4c such as an infrared lamp to a temperature higher than the highest curing temperature (in this case, n) of the dispersion medium 24f. The dispersion medium 24f encapsulated in all the microcapsules 24 in the display layer 23 of the recording medium 30 can be thickened or cured to fix the image. Since the dispersion medium 24f of the microcapsule 24 corresponding to all display primary colors is simultaneously thickened or hardened, only one kind of temperature can be set for the recording medium heating unit 4c and one kind of the dispersion medium 24e. As a result, it is possible to easily form an image excellent in stability of image quality that does not change with time and is not easily affected by environmental changes or static electricity.

Note that, for the present embodiment, the force medium side voltage control step and the discharge electrode heating step in which the discharge electrode calorie heating step is performed as a subsequent step of the medium side voltage control step may be performed simultaneously. .

In the head-side voltage application step, the head-side voltage application unit 15 applies all the voltage corresponding to the discharge control voltage only to the discharge electrode 13, and in the medium-side voltage control step, the medium-side voltage control unit 16a uses the recording medium 30. Instead of selectively grounding the counter electrode 32, a part of the voltage corresponding to the discharge control voltage is applied to the discharge electrode 13 in the head-side voltage applying step, and the remaining voltage is applied to the counter electrode of the recording medium 30. Even if it is selectively applied to 32 Good.

In addition, although the recording medium 30 that performs color display using the white colored particles 24a and the colored particles 24b, 24c, 24d colored in the three primary colors (Y, Μ, C) was used, the colored particles 24b, 2 Instead of 4c and 24d, a recording medium that displays colors in combination with a color filter with the three primary colors (R, G, B) in the additive color mixing method and a reflective layer with the three primary colors (Y, M, C) in the subtractive color mixing method is used. It can also be used. Since the image forming method in this case is the same as that of the second embodiment, the description thereof is omitted.

[0064] Since the image forming apparatus of the second embodiment is configured as described above, in addition to the actions obtained in the first embodiment, the following actions are provided.

(1) Since the charge control electrode 32 is formed by being divided into color units of display primary colors of the color display of the recording medium 30, it is possible to form an image by dividing the image information into color units, and color misregistration. Can be reliably prevented and a high-quality color image can be obtained.

Since the image forming method of the second embodiment is configured as described above, in addition to the actions obtained in the first embodiment, the following actions are provided.

(1) In the potential difference setting step, a head side voltage applying step for applying a voltage to the discharge electrode 13 by the head side voltage applying unit 15 electrically connected to the discharge electrode 13 and a counter electrode 32 are electrically connected. Medium-side voltage control step of grounding the counter electrode 22 by the medium-side voltage control unit 16a, so that a voltage is applied to the entire discharge electrode 13 in the head-side voltage application step, and the medium-side voltage control step is performed. By selectively grounding the counter electrode 22, a potential difference corresponding to the discharge control voltage can be selectively generated between the discharge electrode 13 and the counter electrode 22 to prepare for the discharge.

(2) Since the selection unit of the counter electrode 22 in the medium-side voltage control process is the color unit of the display primary color of the color display of the recording medium 30, the image information is divided into color units to reliably prevent color misregistration. Therefore, it is possible to reduce the man-hours required to form a color image without having to fix the image by a curing process or an initialization process each time an image is formed in color units. By repeating the potential difference setting step, the discharge electrode heating step, and the curing step, color misregistration can be further prevented and a higher quality color image can be obtained. Industrial applicability The present invention forms an image in a color unit of color display of a recording medium with simple control over a recording medium using an electrophoretic image display material in which a dispersion medium is cured or softened by thermal energy. It is possible to reliably prevent the occurrence of misalignment, and the productivity that enables high quality images to be formed without fine alignment between the image forming apparatus and the recording medium. It is possible to provide an excellent image forming method and to form an image in units of colors by a heating and discharging type print head. The formed image can be fixed and displayed over a long period of time, and the image quality can be improved. We provide an image forming apparatus that has excellent reliability, can simplify the structure with only the consumables necessary for color image formation, is easy to maintain, and saves resources. Development type recording medium Passport, driver's license, to realize that to be used for a wide range of applications of the identification card or the like.

Claims

The scope of the claims

[1] Colored particles are dispersed in a dispersion medium that is softened by heat energy by using a heat discharge type print head that includes a discharge electrode having an electron emission portion and a heating unit that selectively heats the discharge electrode. An image forming method for forming an image on a recording medium having a display layer using an electrophoretic image display material,

A softening step of softening the dispersion medium by heating the recording medium, and a surface opposite to the recording surface of the recording medium, wherein the recording surface is disposed opposite to the discharge electrode and the heat-discharge type print head. Based on the image information and the potential difference setting process in which a potential difference corresponding to the discharge control voltage is set between the counter electrode formed on the electrode and the counter electrode, and an electric field is formed! A discharge electrode heating step of selectively heating the discharge electrode.

[2] Disperse the colored particles in a dispersion medium that is cured by thermal energy using a heat-discharge type print head that includes a discharge electrode having an electron-emitting portion and a heating means that selectively heats the discharge electrode. An image forming method for forming an image on a recording medium having a display layer using an electrophoretic image display material,

A potential difference corresponding to a discharge control voltage between the discharge electrode and a counter electrode formed on a surface opposite to the recording surface of the recording medium, the recording surface of which is disposed to face the heating / discharge type print head. A potential difference setting step for forming an electric field by setting the discharge electrode, a discharge electrode heating step for selectively heating the discharge electrode based on image information, and a curing step for curing the dispersion medium by heating the recording medium And an image forming method.

[3] The potential difference setting step is electrically connected to the counter electrode and a head side voltage applying step of applying a voltage to the discharge electrode by a head side voltage applying unit electrically connected to the discharge electrode. The image forming method according to claim 1, further comprising: a medium side voltage control step of grounding or applying a voltage to the medium electrode by a medium side voltage control unit.

[4] The potential difference setting step, the discharge electrode heating step, the softening step, or the curing step are repeatedly performed for each color of the display primary color of the color display of the recording medium, and the softening step or the curing step. The image forming method according to any one of claims 1 to 3, wherein the temperature at which the recording medium is heated differs for each color of the display primary color.

5. The image forming method according to claim 1, wherein the medium side voltage control step is selectively performed based on image information.

6. The image forming method according to claim 5, wherein a selection unit of the medium electrode in the medium-side voltage control step is a color unit of a display primary color for color display of the recording medium.

7. The image forming method according to claim 1, further comprising an initialization step of initializing the recording medium as a pre-step of the potential difference setting step.

[8] An image forming apparatus for forming an image on a recording medium having a display layer using an electrophoretic image display material in which colored particles are dispersed in a dispersion medium that is softened or cured by thermal energy. ,

A heat discharge type print head comprising a discharge electrode having an electron emission portion and a heating means for selectively heating the discharge electrode, and a recording surface is disposed opposite to the discharge electrode and the heat discharge type print head. A potential difference setting unit configured to set an electric potential difference corresponding to a discharge control voltage between a counter electrode formed on a surface opposite to the recording surface of the recording medium to form an electric field; and heating the recording medium. An image forming apparatus comprising: a recording medium calorie heating section for softening or curing the dispersion medium.

9. The image forming apparatus according to claim 8, further comprising a restorer that initializes the recording medium.

[10] The potential difference setting unit includes a head-side voltage application unit that applies a voltage to the discharge electrode, a medium-side voltage control unit that selectively performs grounding or voltage application to the counter electrode based on image information, The image forming apparatus according to claim 8, wherein the image forming apparatus comprises: