JP2003080712A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recorder exhibiting high drying speed, high image quality and high productivity in which blur is suppressed, good gradation reproducibility is realized and ejecting direction is stabilized. SOLUTION: The ink jet recorder uses a writing head 1 comprising an ink chamber 2 having openings, heat generating means 4 disposed in the ink chamber 2 and being applied with an electric signal based on an image data signal, bias electrodes 3 for applying an electrostatic field to ink in the ink chamber 2, a bias voltage control section for applying a voltage to the bias electrode 3, and means 7 for irradiating the ink 6 with light wherein the ink 6 is produced by dispersing particles into a solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for ejecting ink by a heating element. More specifically, an ink in which particles are dispersed in a solvent is used and the concentration of particles in ejected ink droplets The present invention relates to an inkjet recording device controlled by irradiation.

[0002]

2. Description of the Related Art The ink jet recording system has been widely put into practical use because it does not require a developing process or the like and the size of a recording head is small so that a recording device can be easily miniaturized. As a conventional inkjet recording system,
There are a piezo element that deforms according to an electric signal and a flexible plate, a heating resistor that generates heat according to an electric signal, and an electrostatic force using an electric signal. In particular, Japanese Patent Publication No. 56-9492 and Japanese Patent Publication No. 61-5991.
A method using a heating resistor that generates heat in response to an electric signal disclosed in Japanese Patent Publication No. 1 and a method using a piezo element and a flexible plate that deforms in response to an electrical signal disclosed in Japanese Patent Publication No. 53-12138. It is known as a technical technology. A serial scanning head, which is mounted on a carriage as a recording head used in an inkjet printer and performs recording while moving in a direction orthogonal to a conveyance direction of recording paper, has been widely put into practical use. With this serial scanning head, it is difficult to increase the recording speed because recording is performed while moving mechanically. Therefore, a line scanning type head that can increase the recording speed by reducing the mechanical moving part by making the recording head the same size as the width of the recording paper is also considered. Realization is not easy for the following reasons. In other words, the ink jet recording method is essentially a drawing failure caused by clogging of individual thin nozzles corresponding to the resolution due to an increase in the ink viscosity caused by the evaporation or volatilization of the ink solvent from the ink ejection portion and the solidification of the ink. Has a problem that occurs. For this reason, in the method using the heating resistor that generates heat in response to an electric signal, the attachment of an unwanted substance due to a thermal or chemical reaction with ink causes a piezo element and a flexible plate that are deformed according to an electric signal. In the method used, the complicated structure in the ink flow path or the like makes it easier to induce clogging. With a serial scanning type head that uses several tens to hundreds of nozzles,
Although the frequency of clogging can be suppressed to a low level, with a line scanning head that requires thousands of nozzles, clogging occurs at a fairly high frequency with probability, which is a major problem in terms of reliability. is there.

Further, there is a problem that the ink jet recording system is not suitable for improving the resolution. In the method using a heating resistor that generates heat in response to an electric signal, the ejected ink droplet has a diameter of 20 μm (when landed on a recording paper,
It is difficult to generate an ink droplet having a particle diameter equal to or smaller than the particle diameter of an ink droplet that forms a dot having a diameter of about 50 μm.
Further, in the method using a piezo element that deforms according to an electric signal and a flexible plate, it is difficult to manufacture a head with high resolution because of a processing problem because the recording head has a complicated structure.

In order to overcome these problems, a method of ejecting ink from the ink surface using the pressure of ultrasonic waves generated by an ultrasonic wave generating element array formed of a thin film piezoelectric material is disclosed in Japanese Patent Publication No. 6-45233. , Patent No. 27
No. 42077 and Japanese Patent Application Laid-Open No. 8-99408. These methods are so-called nozzleless methods that do not require nozzles for individual dots or partition walls of ink flow paths, so they are effective for preventing and recovering from clogging, which was a major problem for making line heads. Is.
Further, since it is possible to stably generate and eject ink droplets having a very small diameter, it is said that it is also suitable for high resolution.

On the other hand, the ink used in the ink jet recording system uses an ink containing a large amount of a water-based or organic solvent containing a dye or a pigment as a coloring material and having a low ink viscosity and a low particle concentration due to the above problems. . Therefore, in such an ink jet recording method, image bleeding occurs and it is difficult to form a high-quality / high-resolution image, and it takes time to dry the image forming section, which improves productivity. Is difficult.

In order to overcome the above problems, Japanese Patent Laid-Open No. 9-
Japanese Patent No. 76493 discloses an ink jet method in which ink is ejected from the liquid surface of an ink by an ultrasonic wave generating element, in which ink in which particles are dispersed in a solvent is used, and a particle concentration near the liquid surface is increased by electrostatic force. . According to this method, the concentration of particles in the ejected ink droplets is high, and it is possible to form a high-quality and high-resolution image without blurring of the image.

Further, as a method for drawing an image of high gradation reproducibility and high image quality, a method of controlling the particle concentration in ejected ink droplets can be considered. However, in the inkjet method using the electrostatic force by an electric signal, the Institute of Electronics and Communication Engineers journal paper '83 / 1 Vol. J66-CN
o. As described in 1p51, there is a problem that the displacement amount of the recording pixel position becomes large when the recording electrode interval is narrow due to the electric field interference between the adjacent channels. Therefore, in the above method, since the particle concentration near the liquid surface is controlled by electrostatic force, it is extremely difficult to perform ejection in a stable direction due to electric field interference with an adjacent channel.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is an ink jet recording apparatus which ejects ink by a heating element, with less blurring and gradation reproducibility. It is an object of the present invention to provide an ink jet recording apparatus having good image quality, stable ejection direction, fast drying speed, high image quality and high productivity.

[0009]

In order to achieve the above object, an ink jet recording method according to a first aspect of the present invention ejects ink by applying an electric signal to a heating element that generates heat based on an image data signal, thereby forming an image. In the ink jet recording method for forming the ink, an ink in which particles are dispersed in a solvent is used, and the particle concentration in the vicinity of the ejection portion is controlled by light irradiation and an electrostatic field. The ink jet drawing head according to claim 2, further comprising: an ink chamber having an opening portion; and a heat generating unit configured by a heat generating element to which an electric signal is applied based on an image data signal. The ink is generated by the operation of the heat generating unit. In a drawing head that ejects ink in a chamber from the opening, a bias electrode that applies an electrostatic field to the ink in the ink chamber, a bias voltage control unit that controls a voltage to the bias electrode, and the ink is irradiated with light. And a light irradiation means. According to a third aspect of the present invention, in the inkjet drawing head according to the second aspect, a light irradiation control unit that controls the light intensity of the light irradiation unit is provided. According to a fourth aspect of the present invention, in the inkjet drawing head according to the second or third aspect, the light irradiation means emits light having an absorption wavelength of particles dispersed in the ink. According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus using the ink jet drawing head according to any one of the second to fourth aspects, the ink chamber is filled with ink, and the heat generating means is electrically driven based on an image data signal. In an inkjet recording apparatus that forms an image by ejecting the ink by applying a signal, an ink in which particles are dispersed in a solvent is used as the ink.

According to a sixth aspect of the invention, in the ink jet recording apparatus according to the fifth aspect, the first flying electrode is provided in the vicinity of the opening, and the first flying electrode is provided on the back side of the image receiving surface of the image receiving sheet for receiving the ejected ink droplet. Two flying electrodes are provided. According to a seventh aspect of the present invention, in the inkjet recording apparatus according to the fifth or sixth aspect, an ink circulation unit that circulates the ink between the ink tank containing the ink and the inkjet drawing head is provided. Characterize. The invention according to claim 8 is the invention according to claims 5 to 7.
2. The ink jet recording apparatus according to any one of the above items, further comprising an ink replenishing means for replenishing the ink tank with ink having a high particle concentration in accordance with the particle concentration in the ink. According to a ninth aspect of the present invention, in the ink jet recording apparatus according to any one of the fifth to eighth aspects, temperature detecting means for detecting a temperature of ink in the ink tank, and the inside of the ink tank according to the detected temperature are detected. It is characterized by comprising a temperature control means for heating or cooling the ink. According to a tenth aspect of the present invention, in the inkjet recording apparatus according to any one of the fifth to ninth aspects, a temperature detection unit that detects the temperature of the drawing head is provided in the drawing head, and the inkjet drawing is performed according to the detected temperature. It is characterized in that it is provided with a temperature adjusting means for heating or cooling the head. With the above configuration, the ink in which the particles are dispersed in the solvent is used, an electrostatic force is applied to the ink in the drawing head, and the ink in the drawing head is irradiated with light to move the particles to the ejection liquid surface, Since the particle concentration on the discharge liquid surface is controlled by the irradiation intensity of the light source, there is little bleeding, good gradation reproducibility, stable discharge direction, fast drying speed, high image quality and high productivity inkjet recording device. Can be provided.

The embodiments of the present invention will be described in detail below. The first embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this embodiment. FIG. 1 is a sectional view of a heating element type ink jet recording head according to the present invention. In FIG. 1, 1 is a heating element type inkjet recording head, 2 is an ink chamber, and 3 (3
a, 3b) is a bias electrode, 4 is heat generating means, 6 is ink, 7 is light irradiation means, and 8 is a substrate. Reference numeral 204 is a grooved plate, and 205 is an orifice. The ink chamber 2 is provided with a predetermined number of orifices 205 in a horizontal row to form ejection ports (ejection ports 205-1, 205-2, 205-3 in the figure). Ink enters the ink chamber 2 from one side (the left side in the drawing) and flows out to the other (the right side in the drawing) and is constantly circulated. The discharge port 205 is a part of the heat generating means 4 described in detail in FIG. A discharge control unit (not shown) is connected to the heat generation unit 4, and when an electric signal based on image data is applied to the heat generation unit 4 from the discharge control unit, the heat generation unit 4 rapidly generates heat to generate heat. The ink 6 in the means 4 is heated to generate bubbles, which causes the ink to be ejected as ink droplets from the meniscus liquid surface of the opening and fly to perform drawing.

FIG. 2 is a partial sectional view of FIG. 1 and is shown in FIG.
2B is a partial sectional view of a section taken along the dashed-dotted line XY in FIG. 1, a front partial view from the orifice side of the head, and FIG. 2B is a sectional view taken along the dashed-dotted line XY in FIG. 2A. The partial view of the cut surface in the case of doing is shown. The heat generating means 4 shown in the figure is a groove in which a predetermined number of grooves having a predetermined width and depth are provided at a predetermined linear density on the surface of a substrate 203 on which the electrothermal converter 202 is provided. It has a structure in which the orifice 205 and the liquid discharge part 206 are formed by joining them so as to cover with the attachment plate 204. In the case of the recording head shown in the figure, it is shown as having a plurality of orifices 205, but of course the present invention is not limited to this, and the application to the recording head in the case of a single orifice also applies to the present invention. It falls into the category. The liquid ejecting unit 206 has an orifice 205 for ejecting liquid droplets at its end, and thermal energy generated by the electrothermal converter 202 acts on the liquid to generate bubbles, and the volume thereof rapidly expands and contracts. A heat acting portion 207, which is a place where various state changes are caused.

The heat-acting portion 207 is located above the heat-generating portion 208 of the electrothermal converter 202, and has a heat-acting surface 209 that comes into contact with the liquid of the heat-generating portion 208 as its bottom surface. The heat generating unit 208 is a lower layer 210 provided on the substrate 203.
And a heating resistance layer 211 provided on the lower layer 210.
And electrodes 213 and 214 provided on the surface of the heat generating resistance layer 211 for energizing the heat generating resistance layer 211 to generate heat. The electrode 213 is an electrode common to the heat generating parts of the respective liquid ejecting parts, and the electrode 214
Is a selection electrode for selecting the heat generating portion of each liquid ejecting portion to generate heat. The upper layer 212 isolates the heat generating resistance layer 211 from the liquid in the liquid ejecting unit 206 in order to chemically and physically protect the heat generating resistance layer 211 from the liquid used, and also separates the electrodes 213 and 214 from each other through the liquid. It has a protective function of the heat generating resistance layer 211 for preventing a short circuit. The upper layer 212 has the above-mentioned function, but when the heating resistance layer 211 is liquid resistant and there is no fear of electrical short circuit between the electrodes 213 and 214 through the liquid. However, it is not necessarily provided, and may be designed as an electrothermal converter having a structure in which the liquid directly contacts the surface of the heating resistance layer 211.

The lower layer 210 mainly has a heat flow rate control function. That is, when the droplets are discharged, the heat generated in the heat generating resistance layer 211 is conducted to the heat acting portion 207 side rather than to the substrate 203 side.
After the liquid droplets are discharged, that is, the power supply to the heating resistance layer 211 is turned off.
After being heated, the heat in the heat acting portion 207 and the heat generating portion 208 is rapidly released to the substrate 203 side, and the heat acting portion 2
It is provided for the liquid at 07 and bubbles generated to be drastically reduced. As described above, when the droplets are ejected, the heat acting portion 2
The heat flow rate to the 07 side is as large as possible, and when the heating resistor layer 211 is turned off, the heat flow rate to the substrate 203 side is set to be as large as possible.
High efficiency of droplet discharge energy, improvement of thermal response and continuous repeated droplet discharge performance, improvement of droplet discharge frequency, uniform discharge droplet volume, stabilization of droplet discharge direction, droplet discharge speed In order to realize the uniformity of the above, and the improvement of the fidelity and certainty of the response to the recording signal, it is only necessary to execute the recording so that the above relationship is established in the bubble volume change curve.

This point will be described more specifically. FIG. 3 shows a temporal change in the bubble volume generated in the heat acting portion 207 when an electric signal having a pulse waveform indicated by the symbol P is input to the electrothermal converter 202 provided in the recording head. Now, when the pulsed electric signal P0 is input to the electrothermal converter 202 at time t0 and time tf, a bubble is generated in the heat acting portion 207 at time ti, and the volume Vv of this bubble is Start to increase from time ti,
The maximum volume Vvp is reached at time tp. Time tf
When the electric signal p is turned off at, the volume Vv of the bubble starts to decrease after the time tp. The rate of decrease of the bubble volume Vv when the electric signal P0 is turned off depends on the temporal change rate of the bubble volume Vv at time τ1.

In the present invention, the concentration of particles in the vicinity of the liquid surface is further controlled. An ink in which particles to be charged by light irradiation are dispersed in a solvent is used, the particles are charged by using light irradiation means, and the bias electrode is used. Is used to control the particle concentration near the liquid surface by generating an electrostatic field in the ink. Returning to FIG. 1, the bias electrode 3a is disposed in the opening of the ink chamber 2, and the circular bias electrode 3b is disposed inside the substrate 8 in the ink chamber 2. The bias electrodes 3a and 3b are connected to a bias voltage control unit (not shown), and a voltage is applied between the bias electrodes 3a and 3b. By applying a voltage between the bias electrodes 3a-3b, an electrostatic force is applied to the ink 6 in which particles are dispersed in the ink chamber 2. The bias voltage applied at the time of drawing is constant. 7 is a light irradiating means, and the ink chamber 2
The substrate 8 is placed inside and the ink in the ink chamber 2 is irradiated. The irradiation of the light irradiation means 7 charges the ink particles. Therefore, the ink particles charged by the light irradiation of the light irradiation unit 7 move to the vicinity of the opening due to the electrostatic field formed by the bias electrodes 3a and 3b, and the density of the charged particles near the opening increases. Here, when the light intensity of the light irradiating means 7 is increased, the number of particles moving to the vicinity of the liquid surface of the opening of the bias electrode 3a is increased. Therefore, by controlling the light intensity of the light irradiating means 7, the bias electrode 3a is controlled. The particle concentration in the vicinity of the opening will be controlled. The particle concentration in the ink droplets ejected from the liquid surface by the heat generation means 4 is controlled by controlling the particle concentration in the vicinity of the opening. It is considered that the particles are charged by the light irradiation because carriers are injected by the light energy when the particles are irradiated with the light. Therefore, when the charged particles are placed in the electrostatic field between the bias electrodes, they repel the same polarity as the charged polarity and move to the opposite polarity. Therefore, when the particles are positively charged, the bias electrode 3a at the opening of the ink chamber 2 may be negative and the other bias electrode 3b may be positive. Although the light irradiating means 7 is arranged on the substrate 8 inside the ink chamber 2, the light irradiating means 7 is not limited to this, and the ejection opening portion 1 may be irradiated with the ink liquid near the ejection opening portion 11.
If a part of the vicinity of 1 is composed of a transparent substrate and is arranged there, the particle concentration of the ink in the vicinity of the ejection opening 11 can be efficiently controlled. Furthermore, the discharge opening 1
It may be located anywhere such as the upper surface and the side surface inside the ink chamber as long as it is a position to irradiate ink in the vicinity of 1. It may be arranged not only inside the ink chamber 2 but also at a position where the liquid surface is irradiated from outside.

Further, the ejected ink droplets land on a recording medium conveyed by a recording medium conveying means (not shown),
Drawing is done. Since ink is circulated between the ink tanks (not shown) to the recording head 1 by an ink circulation means (not shown), ink is sufficiently supplied into the ink chamber even when drawing is performed. Further, sufficient particles are supplied to the ink 6 in the ink chamber 2 by having a replenishing means for replenishing the ink in accordance with the consumption of the particles in the ink. Further, since the temperature of the ink in the ink tank and the temperature of the drawing head are stably controlled, the liquid properties of the ink are also stable, and stable ejection can be performed.

The ink used in the present invention will be described below. The ink used in the present invention is obtained by dispersing particles containing at least a photoconductive compound in a solvent, and the dispersed particles may be organic particles or inorganic particles. The solvent used in the ink of the present invention is not particularly limited, but the specific electric resistance is 10 ⁴ Ωcm to 1
It is preferably 0 ¹⁵ Ωcm and a relative dielectric constant of 2.0 to 80. This is because when the resistivity value is extremely low, it becomes difficult to maintain the particle concentration gradient due to the disappearance of electrolysis induced by light, and when the dielectric constant is extremely high, the electric field is generated by the polarization of the solvent. This is because it is alleviated and it becomes difficult to control the particle charge. Viscosity of solvent is 1.0cP-10c
P and the surface tension is preferably 19 to 74 dyne / cm (mN / m). The particles dispersed in the solvent may be colored particles or non-colored particles. When using colored particles, the colored photoconductive compound itself may be dispersed in a solvent as dispersed particles, other dispersed particles,
For example, it may be contained in the resin particles. When it is contained, a pigment or the like is generally coated with a resin material of dispersed resin particles to obtain resin-coated particles, and a dye or the like is generally pigmented by dispersing resin particles into colored particles. is there.

As the photoconductive compound used in the present invention, any photoconductive compound conventionally known as an electrophotographic photosensitive member can be used and is not particularly limited. For example, RMSchaffert. “Electrophotography” Fo
cal Press, London (1980), SWIng, MDTabak, WEHa
as “Electrophotography Fourth International Confer
ence "SPSE (1983), Isao Shinohara, Hidetoshi Tsuchida, Hideaki Kusagawa," Recording Materials and Photosensitive Resins, "published by the Japan Society for Publishing Center (1979), Hiroshi Komon," Chemistry and Industry, "39 (3) 161. (1986
,), Comprehensive Technical Data "Recent Development and Practical Use of Photoconductive Materials and Photoconductors", Japan Science Information Co., Ltd. (1986), The Electrophotographic Society, "Basics and Applications of Electrophotographic Technology," Corona Publishing Co., Ltd. Co., Ltd. (1986), edited by the Institute of Electrophotography, "Presentation Symposium on Organic Photoreceptors for Electrophotography" Proceedings (1985), etc.
The various compounds described in the review are mentioned.

The photoconductive compound used in the present invention may be either an inorganic compound or an organic compound. Examples of the inorganic compound used as the photoconductive compound of the present invention include conventionally known inorganic photoconductive compounds such as zinc oxide, titanium oxide, zinc sulfide, amorphous silicon and lead sulfide. Examples of the organic photoconductive compound used in the present invention include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, azurenium salt derivatives, amino. Substituted chalcone derivative, N, N-
Bicarbazyl derivative, oxazole derivative, styrylanthracene derivative, fluorenone derivative, hydrazone derivative, benzidine derivative, stilbene derivative, polyvinylcarbazole and its derivatives, polyvinylpyrene, polyvinylanthracene, poly-2-vinyl-4- (4 '
-Dimethylaminophenyl) -5-phenyl-oxazole, vinyl polymers such as poly-3-vinyl-N-ethylcarbazole, polymers such as polyacenaphthylene, polyindene, copolymers of acenaphthylene and styrene, triphenylmethane Examples thereof include polymers, condensation resins such as pyrene-formaldehyde resin, bromopyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, and the like. The organic photoconductive compound is not limited to these compounds, and all known organic photoconductive compounds can be used. Two or more kinds of these organic photoconductive compounds can be used in combination depending on the case.

A sensitizing dye may be contained together with the photoconductive compound. Specifically, conventionally known sensitizing dyes used for electrophotographic photoreceptors can be used. These are "Electrophotography" 12, 9 (1973), "Organic Synthetic Chemistry" 23 (11), 10
10 (1966). For example, U.S. Pat.
770, 4,283,475, JP-A-48-25658, JP-A-62.
-71965 and other pyrylium dyes, Applied Optics
Supplement 350 (1969), triazole methane type dyes described in JP-A-50-39548 and the like, and cyanine dyes described in US Pat. No. 3,597,196 and the like, JP-A-60-163047 and 59-59.
The styryl dyes and the like described in -164588 and 60-252517 are advantageously used. Further, particles having photoconductivity using an organic compound may be used. Specific examples thereof include photoconductive particles mainly composed of a charge generating agent, a charge transporting agent, and a binder resin.

As the charge generating agent contained in the photoconductive particles, various organic and inorganic charge generating agents known in the prior art for electrophotographic photoreceptors can be used. For example, cadmium sulfide, zinc oxide, titanium oxide and the organic pigments shown below can be used, and these can be arbitrarily selected as the charge generating agent in which the hue of the colored particles of the color image is appropriate.

Examples of organic pigments include azo pigments such as monoazo, bisazo, and trisazo pigments, phthalocyanine pigments such as metal-free or metal phthalocyanine, perylene pigments, indigo, thioindigo derivatives, quinacridone pigments, polycyclic quinone pigments, Examples thereof include bisbenzimidazole-based pigments, squalium salt-based pigments, and azurenium salt-based pigments, and these may be used alone or in combination of two or more. Further, in the photoconductive particles used in combination with the charge transporting agent, those having good compatibility with the charge generating agent used in combination are selected, and specifically, known as the organic photoconductive compound described above. The compound group can be mentioned.

Regarding the mixing ratio of the organic photoconductive compound and the binder resin, the upper limit of the content of the organic photoconductive compound is determined by the compatibility between the organic photoconductive compound and the binder resin. Crystallization of the organic photoconductive compound occurs, which is not preferable. Since the photoconductivity decreases as the content of the organic photoconductive compound decreases, it is preferable to include as many organic photoconductive compounds as possible within a range in which crystallization of the organic photoconductive compound does not occur. The content of the organic photoconductive compound is 5 to 120 parts by mass, preferably 10 to 100 parts by mass of the binder resin.
It is 100 parts by mass.

The binder resin that can be used in the photoconductive particles of the present invention may be any of the resins used in conventionally known electrophotographic photoreceptors, and the weight average molecular weight is preferably 5
× 10 ³ to 1 × 10 ⁶ , more preferably 2 × 10 ^{4 to} 5
× 10 ⁵ . The glass transition point of the binder resin is preferably -40 ° C to 200 ° C, more preferably -1.
It is 0 ° C to 100 ° C. For example, Ryuji Shibata and Jiro Ishiwata,
Macromolecules, Volume 17, Page 278 (1968), Harumi Miyamoto,
Hidehiko Takei, Imaging, 1973 (No.8), Koichi Nakamura, "Practical Technology of Binders for Recording Materials," Chapter 10, CHC Publishing (1
985), "The Recent Development and Practical Use of Photoconductive Materials and Photoconductors," edited by The Institute of Electrophotography, Japan Science Information Co., Ltd. (1986), edited by The Institute of Electrophotography, "Basics and Applications of Electrophotographic Technology," Chapter 5 Corona Co., Ltd. (1988), D.Tatt, SCHeidecker, Tappi,
49 (No.10), 439 (1966), ESBaltazzi, RGBlanclot
te et al., Phot. Sci. Eng. 16 (No. 5), 354 (1972),
Nguyen Chan Kay, Isamu Shimizu, Eiichi Inoue, The Electrophotographic Society of Japan 18 (No. 2), 22 (1980) and the like are mentioned in the literature and review compounds.

Specifically, olefin polymers and copolymers, vinyl chloride copolymers, vinylidene chloride copolymers, vinyl alkanoate polymers and copolymers, allyl alkanoate polymers and copolymers, styrene and Polymers and copolymers of the derivatives, butadiene-styrene copolymers, isoprene-styrene copolymers, butadiene-unsaturated carboxylic acid ester copolymers, acrylonitrile copolymers, methacrylonitrile copolymers, alkyl vinyl ether copolymers. Polymers, acrylic acid ester polymers and copolymers, methacrylic acid ester polymers and copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, itaconic acid diester polymers and copolymers , Maleic anhydride copolymer, acrylamide copolymer, methacrylamide Polymer, hydroxyl-modified silicone resin, polycarbonate resin, ketone resin, polyester resin, silicone resin, amide resin, hydroxyl- and carboxyl-modified polyester resin, butyral resin, polyvinyl acetal resin, cyclized rubber-methacrylic acid ester copolymer , A cyclized rubber-acrylic ester copolymer, a copolymer containing a nitrogen atom-free heterocycle (as a heterocycle, for example, a furan ring, a tetrahydrofuran ring, a thiophene ring, a dioxane ring, a dioxofuran ring, a lactone ring, a benzofuran Ring, benzothiophene ring, 1,3-dioxetane ring, etc.), epoxy resin and the like.

Furthermore, if necessary, various conventionally known additives for electrophotographic photoreceptors can be used.
These additives include chemical sensitizers for improving photoconductivity, various plasticizers for improving dispersibility of particles with the binder resin, surfactants and the like.

Examples of the chemical sensitizer include halogen, benzoquinone, chloranil, fluoranyl, bromanil,
Dinitrobenzene, anthraquinone, 2,5-dichlorobenzoquinone, nitrophenol, tetrachlorophthalic anhydride, phthalic anhydride, maleic anhydride, N-hydroxymaleinimide, N-hydroxyphthalimide, 2,
Electron-withdrawing compounds such as 3-dichloro-5,6-dicyanobenzoquinone, dinitrofluorenone, trinitrofluorenone, tetracyanoethylene, nitrobenzoic acid and dinitrobenzoic acid, Hiroshi Komon et al. "Recent photoconductive materials and photoconductors Development / Practical use ”Chapters 4-6, Japan Science Information Co., Ltd.
A polyarylalkane compound, a hindered phenol compound, a p-phenylenediamine compound, and the like, which are cited as references in the Publishing Department (1986), are mentioned. Also, JP-A-58-65
No. 439, No. 58-102239, No. 58-1294.
The compounds described in No. 39, No. 62-71965 and the like can also be mentioned.

Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, diphenyl phthalate, triphenyl phosphate, dimethyl adipate, methyl octoate, methyl phthalyl glycolate and dimethyl glycol phthalate. It is preferable that these plasticizers are contained in a range that does not deteriorate the photoconductivity of the photoconductive particles. The addition amount of these various additives is not particularly limited, but is usually 0 with respect to 100 parts by mass of the photoconductor. 0.001 to 2.0 parts by mass.

The dispersed resin particles containing these photoconductive compounds can be produced by a conventionally known mechanical pulverization method or polymerization granulation method. As the mechanical pulverization method, if necessary, a binder resin and a photoconductive compound are mixed,
Method of directly pulverizing with a conventionally known pulverizer through melting and kneading to form fine particles, using a dispersion polymer together, and further dispersing with a wet disperser (for example, ball mill, paint shaker, Keddy mill, dyno mill, etc.), photoconductive property Examples thereof include a method of dispersing particles in the presence of a dispersing polymer.
Specifically, a method for producing a paint or a liquid developer for electrostatic photography can be used. For these, for example,
Translated by Kenji Ueki "Paint Flow and Pigment Dispersion" Kyoritsu Publishing (1971
), "Solomon, Science of Paint", "Paint and Surfac
e Coating Theory and Practice ", Yuji Harazaki" Coating Engineering "Asakura Shoten (1971), Yuji Harazaki" Basic Science of Coating "Maki Shoten (1977) and other publications.

The dispersed resin particles and colored particles (or particles) in the ink of the present invention may be positively or negatively charged electroscopic particles. It is possible to impart an electroscopic property to these particles by appropriately utilizing the technique of a developer for wet electrostatic photography. Specifically, the above-mentioned "Recent Electrophotographic Development System and Development and Practical Use of Toner Materials" 139-
Pp. 148, "Basics and Applications of Electrophotography" edited by The Institute of Electrophotography, pp. 497-505 (Corona Publishing Co., Ltd., 1988), Yuji Harasaki, "Electrophotography" 16 (No.2), 44 (1977), etc. This is done by using the electro-photographic material and other additives.
Examples of preferable electrophoretic materials include metal soaps, organic phosphoric acid or salts thereof, organic sulfonic acids or salts thereof, amphoteric surfactants and the like.

For example, the metallic soaps have 6 to 6 carbon atoms.
24 fatty acids (for example, 2-ethylhexynoic acid, 2-ethylcaproic acid, lauric acid, paramitic acid, elaidic acid, linoleic acid, ricinoleic acid, oleic acid, stearic acid, enanthic acid, naphthenic acid, ethylenediaminetetraacetic acid, etc.), Metal salts of resin acids, dialkyl succinic acid, alkyl phthalic acid, alkyl salicylic acid, etc. (as metal of metal ions, Na, K, Li, B, Al, Ti, Ca,
Pb, Mn, Co, Zn, Mg, Ce, Ag, Cd, Z
r, Cu, Fe, Ba, etc.) (eg US Pat.
No. 11,936, No. 3,900,412, Japanese Patent Publication No. 49-
27707, JP-A-51-37651 and JP-A-52-3.
No. 8937, No. 52-107837, No. 53-123.
No. 138, etc.).

Examples of the organic phosphoric acid or salts thereof include mono-, di- or trialkyl phosphoric acid composed of an alkyl group having 3 to 18 carbon atoms, dialkyldithiophosphoric acid and the like (for example, British Patent Nos. 1,411,739 and 1). , 276,36
No. 3, etc.). Examples of the organic sulfonic acids or salts thereof include long-chain aliphatic sulfonic acids, long-chain alkylbenzene sulfonic acids, dialkyl sulfosuccinic acids and the like or metal salts thereof (for example, Japanese Patent Publication No. 47-3712).
No. 8, JP-A Nos. 53-123138 and 51-4743.
No. 7, No. 50-79640, No. 53-30340, etc.).

As the amphoteric surfactant, phospholipids such as lecithin and kephalin (for example, Japanese Patent Publication No. 51-47046).
No., etc.), .beta.-alanines containing an alkyl group having 8 or more carbon atoms (see, for example, JP-A Nos. 50-17642 and 49;
No. 17741), metal complexes of β-diketones (for example, Japanese Patent Publication No. 49-27707, etc.), and copolymers having a maleic acid half amide component (for example, Japanese Patent Publication No. 6-19596, Japanese Patent Publication No. 6-19596). 6-19595, etc.) and the like. These electrophoretic materials can be used alone or in combination of two or more.

The electrophoretic material is a dispersion solvent 10 which is a carrier liquid.
It is preferable to use about 0.001 to 1.0 parts by mass with respect to 00 parts by mass. Further, various additives may be added if desired. The upper limit of the total amount of additives is limited by the specific electric resistance, viscosity, or surface tension of the ink. That is,
The specific electric resistance of the ink is about 10 ⁴ Ωcm to 10 ¹⁵ Ωcm,
Dielectric constant of about 2.0-80, viscosity of 1.0 cP-30
cP, surface tension 19-74 dyne / cm (mN /
It is desirable to adjust so that it is about m).

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment of the present invention, the flying electrodes 9a and 9b are provided in the vicinity of the outlet of the ejection port 205 and on the back side of the image receiving surface of the image receiving sheet that receives the ejected ink droplets, respectively.
It is characterized by having. And the flying electrodes 9a, 9
A voltage is applied to b by the flight control means (not shown) in the direction in which the ink droplets are accelerated. In addition, the discharge port 20
5 is substantially the same as that of the first embodiment except that the flying electrodes 9a and 9b are provided on the back side of the image receiving surface of the image receiving sheet that receives the discharged ink droplets and the vicinity of the outlet of the ink. The steps up to the ejection of the droplets are the same as in the first embodiment. That is, in FIG.
Reference numerals a and 3b are bias electrodes for generating an electrostatic field in the ink, and 7 is a light irradiation means. Bias electrodes 3a and 3b for generating an electrostatic field in this ink, and light irradiation means 7
The particle concentration near the liquid surface is controlled by.
That is, by applying a voltage between the bias electrodes 3a-3b, an electrostatic field is formed in the ink 6 in which particles are dispersed in the ink chamber 2. Further, by irradiating the ink 6 in the ink chamber 2 with light by the light irradiation means 7, the particles in the ink 6 are charged and move to the vicinity of the liquid surface of the opening of the bias electrode 3a. Here, when the light intensity of the light irradiating means 7 is increased, the number of particles moving to the vicinity of the liquid surface of the opening of the bias electrode 3a is increased. Therefore, by controlling the light intensity of the light irradiating means 7, the bias electrode 3a is controlled. Control the particle concentration near the opening of. By controlling the particle concentration in the vicinity of the opening of the bias electrode 3a, the particle concentration in the ink droplets ejected from the liquid surface by the heat generation means 4 is controlled. Therefore, according to the second embodiment of the present invention, when the particles are positively charged, the ejection port 205
By applying a potential of 9a> 9b between the flying electrode 9a near the exit of the sheet and the flying electrode 9b on the back side of the image receiving surface of the image receiving sheet, the ink droplets ejected from the ejection port 205 are ejected to the flying electrode 9a, Acceleration is performed by the electric field generated by 9b, so that even if the distance between the recording head and the recording medium becomes wide, it is possible to accurately land at the landing target position on the recording medium. At this time, the relation between the potential applied to the bias electrode and the potential applied to the flying electrode is 3b> 3a ≧ 9a> 9b. Further, when the particles are negatively charged, the direction of the inequality sign is opposite.

<Example 1> Drawing was performed using the ink jet recording head shown in FIG. By increasing the particle concentration in the ink droplet, the drawn image was less likely to bleed and a high-definition image could be drawn. Also, there was almost no waviness of the paper due to the large amount of ink placed on the plain paper. Furthermore, by controlling the particle concentration in the ink droplets by the intensity of the irradiation light, it is possible to draw a more accurate image in which the gradation reproducibility is better and the landing position is stable without electric field interference between recording channels. I was able to do it.

Example 2 Drawing was performed using the ink jet recording head shown in FIG. The image drawn in the same manner as in Example 1 was less likely to bleed, and a high-definition image could be drawn. Also, there was almost no waviness of the paper due to the large amount of ink placed on the plain paper. Furthermore, by controlling the particle concentration in the ink droplets by the irradiation light intensity,
It was possible to draw an image with higher gradation reproducibility and more stable and stable landing position without electric field interference between recording channels. Furthermore, by accelerating the ink droplets ejected by the flying electrodes by the electric field, good landing accuracy could be obtained even if the distance between the recording head and the recording medium was widened.

[0039]

According to the present invention, an ink in which particles are dispersed in a solvent is used as the ink, and a constant bias voltage is applied to the ink to control the light intensity applied to the ink, whereby particles near the liquid surface are controlled. By controlling the density and further ejecting ink droplets by the heat generating means,
It is possible to provide an ink jet recording apparatus with less blurring, good gradation reproducibility, stable ejection direction, fast drying speed, high image quality and high productivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heating element type ink jet recording head according to the present invention.

2 is a partial cross-sectional view of FIG. 1, in which (a) is a partial cross-sectional view of the cross section taken along the dashed line XY in FIG. 1;
(B) is a partial sectional view of a section taken along the dashed line XY in (a).

FIG. 3 is a diagram showing a change over time in the volume of bubbles generated in the heat acting portion of FIG.

FIG. 4 is a sectional view of an ink jet recording head according to a second embodiment of the invention.

[Explanation of symbols] 1. Inkjet recording head according to the present invention 2 ink chamber 205 Orifice 3, 3a, 3b Bias electrodes 4 Heat generation means 6 ink 7 Light irradiation means 8 substrates 9 Flying electrode

Claims (10)

[Claims] 1. An ink is ejected by applying an electric signal to a heating element that generates heat based on an image data signal,
In an inkjet recording method for forming an image, an ink in which particles are dispersed in a solvent is used, and the particle concentration in the vicinity of an ejection portion is controlled by light irradiation and an electrostatic field, which is an inkjet recording method. 2. An ink chamber having an opening, and a heat generating means composed of a heat generating element to which an electric signal is applied based on an image data signal, the ink in the ink chamber being moved by the operation of the heat generating means. In a drawing head that ejects from an opening, a bias electrode that applies an electrostatic field to the ink in the ink chamber, a bias voltage control unit that controls the voltage to the bias electrode, and a light irradiation unit that irradiates the ink with light. An inkjet drawing head characterized by having. 3. The ink jet drawing head according to claim 2, further comprising a light irradiation control unit that controls the light intensity of the light irradiation unit. 4. The ink jet drawing head according to claim 2, wherein the light irradiation means emits light having an absorption wavelength of particles dispersed in the ink. 5. The inkjet drawing head according to claim 2, wherein the ink chamber is filled with ink, and an electric signal is applied to the heat generating means based on an image data signal. An inkjet recording apparatus for ejecting ink to form an image, wherein an ink in which particles are dispersed in a solvent is used as the ink. 6. The first flight electrode is provided near the opening, and the second flight electrode is provided on the back side of the image receiving surface of the image receiving sheet for receiving the ejected ink droplets. 5. Inkjet recording device 5. 7. An ink tank containing the ink,
7. The ink jet recording apparatus according to claim 5, further comprising an ink circulation unit that circulates the ink with the ink jet drawing head. 8. The ink jet recording apparatus according to claim 5, further comprising an ink replenishing device that replenishes the ink tank with ink having a high particle concentration in accordance with the particle concentration in the ink. Recording device. 9. The ink tank is provided with temperature detecting means for detecting the temperature of the ink, and temperature adjusting means for heating or cooling the ink in the ink tank according to the detected temperature. Any one of items 5-8
Inkjet recording apparatus according to the item. 10. The drawing head comprises temperature detecting means for detecting the temperature of the drawing head, and temperature adjusting means for heating or cooling the inkjet drawing head according to the detected temperature. The ink jet recording apparatus according to any one of 5 to 9.