JP2005074884A - Recording head, head cartridge using the same, and recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform high quality recording superior in gradation by a method wherein large ink droplets and small ink droplets are discriminately ejected, a drying property to a recording medium is made uniform, and then a phenomena influence to the image quality is suppressed in a dot diameter control system inkjet recording head displaying medium gradation by controlling the size of recording dots. <P>SOLUTION: This recording head 1 comprises a first ejection nozzle array 24Bk for a black color having an ejection hole with a large diameter and second ejection nozzle arrays 25Y, 26M, 27C for colors (yellow, magenta, cyan) each having an ejection hole with a small diameter. A viscosity of an ink ejected from a first ejection hole 4-1 is greater than that of an ink ejected from each of second ejection holes 4-2, and an energy generated by a heating resistor element 2-1 for ejecting the ink corresponding to the first ejection hole 4-1 is greater than an energy generated by a heating resistor element 2-2 corresponding to each second ejection hole 4-2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording head for ejecting liquid, a head cartridge using the recording head, and a recording apparatus. More specifically, the present invention relates to a halftone by controlling the size of recording dots formed by liquid ejected from an ejection port. The present invention relates to a dot diameter control type ink jet recording head, head cartridge, and recording apparatus.

  In addition, the present invention includes a printer, a copying machine, a facsimile having a communication system, and a printer that perform recording on a recording medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramics. The present invention relates to a recording head applicable to an apparatus such as a word processor and an industrial recording apparatus combined with various processing apparatuses, and an application apparatus thereof. Note that “recording” in the present invention not only applies an image having a meaning such as a character or a figure to a recording medium, but also applies an image having no meaning such as a pattern to the recording medium. Is also meant.

  Today, various recording systems have been developed as recording apparatuses. Among them, the inkjet recording system is capable of high-density recording, easy to color, low in price, and downsized. It is widely used because it is possible. For example, it is used in a recording unit such as a printer, a facsimile, or a copying machine.

  As an ink jet recording method, a thermal method using a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, a piezoelectric actuator using a piezoelectric element, a shape memory using a metal phase change caused by a temperature change A system using an electromechanical transducer element using an alloy actuator and an electrostatic actuator using an electrostatic force has been developed.

  As a halftone expression method using this type of ejection method, a dot density control method that records ink dots of a certain size and controls the number of dots per unit area to express a halftone, or A dot diameter control method for expressing a halftone by controlling the size of a recording dot is generally known.

  When an ink ejection method using the electrothermal conversion element is used, the recording head according to this method is relatively easy to manufacture, and can be printed at a high resolution because the density can be increased. However, since it is relatively difficult to control the amount of change in pressure, the diameter of the recording dot cannot be modulated, and it is difficult to use the dot diameter control method. Therefore, Patent Document 1 and Patent Document 2 disclose a configuration in which dot diameter control is performed using two types of discharge port arrays having different discharge port diameters. Further, Patent Document 3 discloses a configuration in which dot diameter control is performed with a discharge port array having one discharge port diameter using a piezoelectric element. In addition, in Patent Document 4 relating to the application of the present applicant, in a recording head provided with a thermal energy action portion for the recording liquid, the thermal energy action portion is equidistant from the recording liquid discharge port that can be driven independently. There is disclosed a configuration in which the gradation width is widened by forming two heat generating elements arranged so that the heat generating capacity of one heat generating element is 1 to 2 times the heat generating capacity of the other heat generating element.

  According to the ink jet recording head configured as in Patent Document 1 and Patent Document 2, recording is performed with higher gradation as compared with an ink jet recording apparatus that ejects only a large volume ink droplet (hereinafter referred to as a large ink droplet). Therefore, recording can be performed at a higher speed than an ink jet recording apparatus that discharges only ink droplets having a small volume (hereinafter referred to as small ink droplets). By combining these large ink droplets and small ink droplets as appropriate, a wide range of gradation is provided.

  Further, according to the ink jet recording head having the configuration as disclosed in Patent Document 3, since the piezoelectric element that can obtain a large displacement by controlling the applied voltage is used, the physical properties (for example, viscosity, surface tension) of the ink can be changed. By adjusting the ink pressure, the amount of ink that can be stably ejected from the same nozzle and the variable range of the size of the dots formed by the ejected ink can be widened, and higher gradation can be obtained. it can.

Next, dye ink and pigment ink will be described.
Dye ink is a “coloring material” in which a component that produces color is dissolved in liquid with a molecular size. When ink is landed on a recording medium, the liquid containing the coloring material is contained in the recording medium. Soaked in and recorded. “Aqueous dye ink” is most commonly used, has good image quality stability and good color development. However, due to the nature of the ink, the light resistance is somewhat lacking, so it is not suitable for display printing or long-term storage.

Pigment ink, on the other hand, is like pigment particles dissolved in water. Water is not colored, and color particles are drifting in the water. The pigment particles are held in a solid state on the recording medium in a stable state and do not penetrate into the recording medium. Therefore, the pigment particles are slightly inferior in terms of color development compared to dyes, but have superior properties in terms of light resistance. is there.
JP 2003-127439 A JP 2002-321354 A Japanese Patent Laid-Open No. 10-034914 JP 2000-043269 A

  However, although the recording heads disclosed in Patent Document 1 and Patent Document 2 can perform gradation recording by changing the size of ink droplets ejected from the ejection openings according to the opening area of the ejection openings, the opening areas are different. Since the ejection ports share the same ink supply unit and supply the same type of ink, the speed of permeation onto the recording medium differs depending on the size of the ink droplets, causing a cockling phenomenon.

  In addition, the invention disclosed in Patent Document 3 is a water-soluble organic solvent having a penetrating rate and a penetrating range on a recording medium because an ink whose viscosity is adjusted by changing the mixing ratio of the water-soluble organic solvent is a dye ink. It is considered that the dot diameter on the recording medium changes depending on the type and ratio thereof. In an actuator of an electromechanical transducer using a piezoelectric body or electrostatic force, ink droplets are ejected in proportion to the displacement of the actuator. This experimental data does not show the relationship between the dot diameter and the ink droplet, and it cannot be easily determined whether the ink droplet diameter has changed due to the ink physical properties.

  When a water-soluble dye as in this example is used, since the ink penetrates and is recorded on the recording medium, the dot diameter changes even if the type of the recording medium changes. Therefore, it is necessary to control the characteristics of the recording medium, or to control the recording medium information and feed it back, and it is difficult to control the dot diameter only by the ink jet recording head and the ink physical properties. is there.

  Therefore, the object of the present invention is to separate large ink droplets and small ink droplets, and to make the drying property to the recording medium more uniform, thereby suppressing the phenomenon that affects the image quality such as cockling and is excellent in gradation. Another object of the present invention is to provide a recording apparatus capable of recording with higher quality.

  The invention according to claim 1 is a configuration in which dot diameter control is performed by having at least two types of discharge port arrays having discharge ports having different discharge port diameters, and a plurality of first discharge ports that discharge a predetermined volume of recording liquid. A plurality of second discharge ports for discharging a recording liquid having a volume smaller than the predetermined volume, a discharge energy generating means for discharging a recording liquid corresponding to each of the first and second discharge ports, and a recording liquid In the recording head including the liquid supply path for supplying the first and second discharge ports, the first discharge port has a viscosity higher than that of the recording liquid discharged from the second discharge port. It is a discharge port for discharging a liquid.

  According to a second aspect of the present invention, in the recording head of the first aspect, the diameter of the first discharge port and the generated energy of the discharge energy generating means for discharging the recording liquid from the first discharge port are the first It is characterized by being larger than the diameter of the two ejection ports and the energy generated by the ejection energy generating means for ejecting the recording liquid from the second ejection port.

  According to a third aspect of the invention, in the recording head according to the first or second aspect of the invention, a recording liquid of 4 mPa · s or more is discharged from at least the first discharge port.

  According to a fourth aspect of the invention, in the recording head according to the first to third aspects of the invention, a recording liquid containing a pigment as a component is discharged from the first and second discharge ports.

  According to a fifth aspect of the present invention, in the recording head according to any one of the first to fourth aspects, the discharge energy generating means comprises an electrothermal conversion element that utilizes a phase change caused by liquid film boiling using a heating resistor. Features.

  According to a sixth aspect of the present invention, there is provided a head cartridge in which a liquid discharge head for discharging a liquid and a recording liquid tank for supplying a recording liquid to the liquid discharge head are integrated. It is a recording head.

  According to a seventh aspect of the present invention, there is provided a recording apparatus including a liquid discharge head for discharging a liquid, wherein the liquid discharge head is the recording head of the first to fifth aspects of the invention or the head cartridge of the sixth aspect of the invention. Features.

The recording head, head cartridge, and recording apparatus of the present invention have the following effects.
The recording head according to claim 1 has a configuration in which at least two types of ejection port arrays having ejection ports with different ejection port diameters are used to perform recording dot diameter control, and ink ejected from ejection ports that eject a large volume of ink is Because it has a higher viscosity than the ink ejected from the ejection port that ejects a small volume of ink, it separates large ink droplets from small ink droplets, and makes the drying property to the recording medium more uniform, thereby improving the image quality such as cockling. This suppresses the phenomenon that affects the image quality and enables recording with higher quality with excellent gradation.

  In the recording head according to the second aspect, the diameter of the first discharge port and the generated energy of the discharge energy generating means for discharging the ink from the first discharge port are larger than those of the second discharge port, so that the viscosity of the ink is increased. However, higher quality recording with excellent gradation can be achieved without adversely affecting the ejection characteristics.

  The recording head according to claim 3 ejects ink of 4 mPa · s or more from the first ejection port that ejects at least a large volume of ink, so that a high-quality image can be obtained at high speed even when printing on plain paper. be able to.

  In the recording head according to the fourth aspect, since the ink having the pigment as a component is discharged from the first and second discharge ports, the colorant pigment is held on the surface of the recording medium. The size of the ejected ink droplet becomes the dot diameter relatively, and the dot diameter can be substantially controlled by the size of the ink droplet without depending on the properties of the recording medium.

  In the recording head according to the fifth aspect, since the discharge energy generating means is composed of an electrothermal conversion element that uses a phase change caused by film boiling of a liquid using a heating resistor, the diameter of the discharge port is maintained while maintaining discharge characteristics. Accordingly, ink droplets having a size corresponding to the size of the ink can be discharged, a phenomenon affecting the image quality such as cockling can be suppressed, and higher quality recording with excellent gradation can be performed.

  According to the sixth aspect of the present invention, since the recording head according to the first to fifth aspects is mounted on the head cartridge in which the recording liquid tank is integrated, it is possible to provide a head cartridge that has excellent gradation and can perform higher quality recording.

  According to the seventh aspect of the present invention, since the recording head according to the first to fifth aspects or the head cartridge according to the sixth aspect is mounted on the recording apparatus, it is possible to provide a higher-quality recording apparatus having excellent gradation.

  The present invention has a configuration in which dot diameter control is performed by having at least two types of ejection port arrays having different ejection port diameters, and includes a plurality of first ejection ports that eject a predetermined volume of recording liquid, and the predetermined volume. A plurality of second ejection ports for ejecting a small volume of recording liquid, ejection energy generating means for ejecting the recording liquid corresponding to each of the first and second ejection ports, and the first and second recording liquids. In the recording head including a liquid supply path that supplies liquid to the discharge port, the first discharge port is a discharge port that discharges a recording liquid having a viscosity higher than that of the recording liquid discharged from the second discharge port. It is characterized by being. According to the recording head of the present invention, the recording dot diameter control is performed with at least two types of ejection port arrays having different ejection port diameters, and the ink ejected from the ejection ports ejecting a large volume of ink has a small volume. Viscosity is higher than the ink ejected from the ejection port that ejects this ink, so large ink droplets and small ink droplets are separated and the drying property to the recording medium is made more uniform, which affects the image quality such as cockling It is possible to suppress the phenomenon and perform higher quality recording with excellent gradation.

Hereinafter, embodiments of the present invention will be described based on examples shown in FIGS.
FIG. 1 is a diagram schematically illustrating a main part of a recording head according to a first embodiment of the present invention. FIG. 1A is a diagram of a surface on which a discharge port of the recording head is formed as viewed from outside the discharge port. FIG. 2B is a cross-sectional view in the main scanning direction of FIG.
As shown in FIG. 1B, the recording head 1 of Example 1 includes a substrate 3 including a heating resistance element 2 (2-1, 2-2) as an energy conversion element, and an ejection port 4 (4-1). , 4-2) and an orifice plate 5. FIG. 1A schematically shows a state in which the substantially transparent orifice plate 5 is placed on the substrate 3, and the ink supply port formed on the substrate 3 is omitted.

  In this embodiment, the substrate 3 is formed of a silicon single crystal having a plane orientation <100>, and the upper surface (connection surface with the orifice plate 5) has a heating resistor element 2 (2) as shown in FIG. −1, 2-2) is formed, and is connected to a driving circuit 6 including a driving transistor for driving the heating resistance element 2 (2-1, 2-2) and a wiring board (not shown). The contact pad 7, the wiring 8 for connecting the drive circuit 6 and the contact pad 7 and the like are formed using a semiconductor process. Further, the substrate 3 has four through holes formed by anisotropic etching in a region excluding the drive circuit 6, the heating resistor 2 (2-1, 2-2), the wiring 8, and the contact pad 7. Ink for supplying black (Bk), yellow (Y), magenta (M), and cyan (C) inks to the respective ejection port arrays 24Bk, 25Y, 26M, and 27C of the respective colors described later. A supply port 9 is formed.

  In this embodiment, the orifice plate 5 provided on the substrate 3 is formed of a photosensitive epoxy resin, and corresponds to the heating resistance elements 2 (2-1, 2-2), and the discharge ports 4 (4-1, 4). -2), a common liquid chamber 11 communicating with the ink flow path 10 and the ink supply port 9 is formed. Here, after the anisotropic etching described above is performed, a silicon oxide film or a silicon nitride film is formed on a silicon substrate, and then an orifice plate having a through-hole, a discharge port, and an ink flow path is formed, and an ink supply port portion It is desirable to remove the silicon oxide film or silicon nitride film because an inexpensive and precise ink jet head can be manufactured.

  In the recording head 1, a plurality of ink flow paths 10 are formed to communicate with the respective ejection ports 4. Each ink flow path 10 is provided with a plurality of heating resistance elements 2. Further, the plurality of heating resistance elements 2 have at least two types of heat generation capabilities. Ink supplied from an ink tank (not shown) is temporarily held in the common liquid chamber 11, and further enters each ink flow path 10 by capillary action to form a meniscus at the discharge port 4. Thereby, the ink flow path 10 is maintained in a state filled with ink. In this state, a drive pulse is applied to the heating resistor element 2 to generate heat, and thermal energy is applied to the ink, thereby causing a state change accompanied by an abrupt volume change (generation of bubbles) in the ink, and an action force based on this state change. Thus, ink is ejected from the ejection port. In addition, each of the plurality of heating resistance elements 2 can be driven independently.

  The recording head 1 having such a substrate 3 and an orifice plate 5 ejects a liquid such as ink from the ejection port 4 using the pressure of bubbles generated by film boiling due to thermal energy applied by the electrothermal transducer. Recording.

  In order to eject a large ink droplet, the ejection port 4-1 and the heating resistor element 2-1 are formed relatively larger than the ejection port 4-2 and the heating resistor element 2-2 that eject a small ink droplet. Has been.

  In the present embodiment, the ejection port array 24Bk for large ink droplet ink (Bk) and the ejection port array 25Y, 26M, 27C for small ink droplet ink (Y, M, C) are arranged on the same substrate 3. It is arranged in the direction (sub-scanning direction). There are 256 discharge ports per color at a pitch of about 42 μm (1/600 inch) for each color row. Each discharge port array is arranged in a line, but it may be a two-row staggered array. When two rows are arranged in a staggered pattern, recording can be performed at a pitch of about 21 μm (1/1200 inch), so that a higher-definition image can be formed.

  Since the black ink (Bk) is used only in the high density portion of the image, the dot granularity is not so noticeable. For this reason, for black (Bk), there is no need to reduce the size of ink droplets by using a relatively large discharge port compared to the color ink discharge ports of yellow (Y), magenta (M), and cyan (C). The print quality does not change much. However, if the ink droplet size of the black ink and the color ink is changed, the ratio of the surface area to the ink per unit volume becomes smaller, so the drying speed of the ink on the recording medium changes, and the recording medium has a cock. It is known that a ring will occur. Here, the amount of components of the black pigment is relatively increased to reduce the difference in the amount of water-soluble organic solvent, pure water, surfactant, etc. occupied by the small ink droplets of color ink and the large ink droplets of black ink. The viscosity is adjusted.

  When the viscosity of the dye ink is changed, the permeability to the recording medium changes and the dot diameter changes (see Patent Document 3). If the type of recording medium is changed, the rate of change is further increased, which makes control difficult. In the pigment ink, since the pigment of the color material is held on the surface of the recording medium, the size of the ink droplet ejected from the ejection port of the inkjet recording head is relatively the dot diameter. Therefore, it is possible to control the dot diameter almost by the size of the ink droplets without being influenced by the properties of the recording medium. Therefore, it is desirable to use pigment ink also in this embodiment. However, dye ink can also be used by collecting information on the recording medium in advance and adjusting the size of ink droplets ejected from the inkjet ejection head.

Here, the ink that is a liquid used in the ink jet recording head will be described. The ink liquid used in the ink jet recording head of the present invention is preferably a printing ink having the following configurations (1) to (10), but is not limited thereto.
(1) Pigment 6 wt% or more (2) Wetting agent 1
(3) Wetting agent 2
(4) Water-soluble organic solvent (5) Anion or nonionic surfactant (6) Polyol or glycol ether having 8 or more carbon atoms (7) Emulsion (8) Preservative (9) pH adjuster (10) Pure water

  That is, a pigment is used as a colorant for printing, a solvent for decomposing and dispersing it is an essential component, and a wetting agent, a surfactant, an emulsion, a preservative, and a pH adjusting agent are added as additives. Contains. By using such inks, even when printing on plain paper, feathering and color bleed phenomenon in images with good color tone (sufficient color development and color reproducibility), high image density, and characters Fully satisfied with these image characteristics, such as clear images without ink, images with little ink see-through phenomenon that can withstand double-sided printing, and images with ink drying, light resistance, water resistance, etc. suitable for high-speed printing A high-quality image that can be formed can be formed.

  Further, the ink viscosity is preferably adjusted and adjusted with a water-soluble organic solvent, a surfactant, pure water or the like without changing the component amount of the pigment. If the amount of the pigment component is changed, the ink density changes and the image quality changes. However, the viscosity of the color ink is constant, and this is not the case when the viscosity of the black ink is changed. Even if the viscosity is adjusted by changing the component amount of the pigment, there is little influence on the image quality and there is no practical problem.

  It is desirable that the ink described above has a high viscosity when a high-quality image is obtained at high speed in printing on plain paper. In particular, when an ink having a viscosity of 4 mPa · s or more, more preferably 8 mPa · s or more is used, a high-quality image can be obtained at high speed even when printing on plain paper. Furthermore, since the viscosity is prepared and adjusted with a water-soluble organic solvent, a surfactant, pure water or the like without changing the amount of pigment components as in color inks, it is more effective for large ink droplets with a slow drying speed.

The method for producing the recording liquid is not limited to the above, and various materials as described below may be added.
The following water-soluble organic solvents can be used for the purpose of preventing the recording liquid from drying and improving the dissolution stability and dispersibility of the compound of the present invention.
Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,5-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1 Polyhydric alcohols such as 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol mono Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monophenyl ether, ether Including polyhydric alcohol aryl ethers such as lenglycol monobenzyl ether, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, etc. Nitrogen heterocyclic compounds, amides such as formamide, N-methylformamide, N, N-dimethylformamide, amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, dimethyl sulfoxide, sulfolane, thio Sulfur-containing compounds such as diethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Of these, diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, petriol, 1,5 are particularly preferable. -Pentanediol, N-methyl-2-pyrrolidone, N-hydroxyethylpyrrolidone, 2-pyrrolidone, and 1,3-dimethylimidazolidinone. By using these, prevention of poor jetting properties due to water evaporation and high solubility In addition, an excellent effect on dispersibility can be obtained.

  Specific examples of the pigment that can be used in the present invention include the following. These pigments may be used in combination of a plurality of types, or may be used in combination with other pigments such as dyes. These colorants are added in amounts that do not exclude the effects of the present invention. Examples of organic pigments include azo, phthalocyanine, anthraquinone, dioxazine, indico, thioindico, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black.

  Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

FIG. 2 is a diagram schematically showing the main part of the recording head of Example 2 of the present invention, and FIG. FIG. 2B is a cross-sectional view across the discharge port with a large opening diameter in FIG. 2A, and FIG. 2C is a cross-sectional view across the discharge port with a small opening diameter in FIG.
As shown in FIGS. 2B and 2C, the recording head 1 of this embodiment includes a substrate 3 including a heating resistance element 2 (2-1, 2-2) as an energy conversion element, and a discharge head. And an orifice plate 5 forming an outlet 4 (4-1, 4-2).

  In the present invention, there are two discharge ports 4 (4-1, 4-2) and two types of heating resistance elements 2 (2-1, 2-2) for black ink, and these two types of heating resistance. The elements 2 (2-1, 2-2) have different heat generation capabilities. Of the two ejection port arrays 24Bk and 34Bk of the black ink (Bk), the ejection ports 4-1 of the ejection port array 34Bk are black (Bk), yellow (Y), magenta (M), cyan (C ) The opening diameter is larger than each of the ejection openings 4-2 of the ink ejection opening arrays 24Bk, 25Y, 26M, and 27C. The heating resistor elements 2-1 corresponding to the black ink (Bk) discharge port arrays 34Bk are black (Bk), yellow (Y), magenta (M), and cyan (C) ink discharge port arrays 24Bk, 25Y,. It has a heat generation capacity larger than that of the heat generation resistive element 2-2 corresponding to 26M and 27C.

  The reason why the two types of heating resistance elements 2-1 and 2-2 have different heat generation capabilities is to increase the gradation width. If the two heating resistance elements 2-1 and 2-2 have the same heat generation capability, there are three gradation levels that can be set. That is, assuming that the heat generation capability of one heat generation resistive element 2 is J, the heat generation state can be set in three stages of 0, J, and 2J (three values).

  On the other hand, when the heat generating capacities of the two types of heat generating resistive elements 2-1 and 2-2 are different as in the present invention, the heat generating state can be taken in four stages. That is, if the heat generation capability of the first heat generation resistive element 2-2 is J1 and the heat generation capability of the second heat generation resistive element 2-1 is J2, in the present invention, 0, J1, J2, A heat generation state can be taken at the stage of J1 + J2 (four values).

FIG. 3 is a diagram schematically illustrating the main part of the recording head according to the third embodiment of the present invention. FIG. 3A is a diagram of the surface of the recording head on which the ejection port is formed as viewed from the outside of the ejection port. FIG. 3B is a cross-sectional view across the discharge port having a large opening diameter in FIG. 3A, and FIG. 3C is a cross-sectional view crossing the discharge port having a small opening diameter in FIG.
As shown in FIGS. 3B and 3C, the recording head 1 of Example 3 includes a substrate 3 including a heating resistance element 2 (2-1, 2-2) as an energy conversion element, and a discharge. And an orifice plate 5 forming an outlet 4 (4-1, 4-2).

In the present invention, the black ink and the color ink (yellow, magenta, cyan) have two types of discharge ports 4-1, 4-2 and two heating resistance elements 2-1, 2-2, The two types of heating resistance elements 2-1 and 2-2 have different heat generation capabilities. Then, the two heating resistance elements 2-1 and 2-2 are driven individually or simultaneously, and in each case, bubbles of different sizes are generated in the flow path, and thereby discharged from the discharge port. Tone recording is performed by changing the amount of ink droplets.
The first discharge ports 4-1 of the first discharge port arrays 24Bk, 25Y, 26M, and 27C for black ink and color ink (yellow, magenta, and cyan) are the second discharge port arrays 34Bk, 35Y, 36M, and 37C. The opening diameter is larger than that of the second discharge port 4-2. The heating resistance element 2-1 corresponding to the first discharge port 4-1 has a larger heating capability than the heating resistance element 2-2 corresponding to the second discharge port 4-2.

  Regarding the black ink Bk, the ink viscosity of the first discharge port 4-1 having a large opening diameter is higher than the ink viscosity of the second discharge port 4-2 having a small opening diameter. The ink viscosity mainly increases the amount of pigment, and the amount of pure water, water-soluble organic solvent, surfactant, etc. is made as much as possible with the ink of the second ejection port 4-2 as much as possible. However, it has been experimentally found that the amount of pure water, water-soluble organic solvent, surfactant, etc. other than the pigment component may be adjusted as long as it does not affect the image quality such as cockling.

  For color inks (yellow, magenta, cyan), the ink viscosity of the first discharge port 4-1 having a large opening diameter is substantially the same as the ink viscosity of the second discharge port having a small opening diameter. When the ink viscosity is low, the ratio of pure water and water-soluble organic solvent increases, so the drying speed of the ink becomes slow, and drying is not able to catch up in today's demand for higher speed recording, cockling and feathering As a result, the image quality deteriorates. Therefore, the ink viscosity is increased within a practically acceptable range in order to relatively increase the drying speed.

  As long as the color ink does not affect the image, the ink viscosity of the first discharge port 4-1 having a large opening diameter and the ink viscosity of the second discharge port 4-2 having a small opening diameter are changed. You can also. At that time, in order to change the ink viscosity, the pigment component is made constant, and the amount of ink discharged from the first discharge port 4-1 and the first concentration are changed by changing the preparation amount of pure water, water-soluble organic solvent, surfactant and the like. The ink density discharged from the second discharge port 4-2 can be made constant, and the image quality is stable.

  It is desirable that the ink described above has a high viscosity when high-quality images are obtained at high speed in printing on plain paper. In particular, when an ink having a viscosity of 4 mPa · s or more, more preferably 8 mPa · s or more is used, a high-quality image can be obtained at high speed even when printing on plain paper. In addition, if the viscosity is prepared and adjusted with a water-soluble organic solvent, a surfactant, pure water or the like without changing the component amount of the pigment as in the color ink, it is more effective for large ink droplets with a slow drying speed.

  The recording head which is the droplet discharge head of the first to third embodiments described above exemplifies a case where four color inks of black Bk, cyan C, magenta M, and yellow Y are used. The present invention can be similarly applied even when there are more colors such as including magenta LM.

FIG. 4 is a perspective view showing a head cartridge according to Embodiment 4 of the present invention.
The head cartridge 41 according to the fourth embodiment is a head cartridge in which the recording head 42 according to any one of the first to third embodiments and a liquid container that holds the liquid supplied to the recording head 42 are integrated. Higher quality recording with excellent gradation is possible.

Next, an example of an ink jet recording apparatus equipped with the recording head of the present invention will be described.
FIG. 5 is a main part perspective view showing an ink jet recording apparatus according to a fifth embodiment of the present invention, and FIG. 6 is a side view of a mechanism part of the recording apparatus.
In the ink jet recording apparatus of the fifth embodiment, a carriage 63 that can move in the main scanning direction inside the recording apparatus main body 51, a recording head 64 that is an ink jet head that implements the present invention mounted on the carriage, and supplies ink to the recording head. A paper feed cassette (or a paper feed tray) that accommodates a printing mechanism portion 52 composed of an ink cartridge 65 and the like and can stack a large number of sheets 53 from the front side in the lower portion of the recording apparatus main body 51 may be used. 54 can be removably mounted, the manual feed tray 55 for manually feeding the paper 53 can be opened, and the paper 53 fed from the paper feed cassette 54 or the manual feed tray 55 can be removed. After taking in and recording a required image by the printing mechanism 52, the image is discharged to a discharge tray 56 mounted on the rear side.

  The printing mechanism 52 holds the carriage 63 slidably in the main scanning direction (the direction perpendicular to the paper in FIG. 6) with a main guide rod 61 and a sub guide rod 62 which are guide members horizontally mounted on left and right side plates (not shown). According to the present invention, yellow (Y), cyan (C), light cyan (LC), magenta (M), light magenta (LM), and black (Bk) ink droplets are ejected onto the carriage 63. A recording head 64 composed of an ink jet head is mounted with a plurality of ink ejection openings (nozzles) arranged in a direction intersecting the main scanning direction and the ink droplet ejection direction facing downward. In addition, each ink cartridge 65 for supplying ink of each color to the recording head 64 is replaceably mounted on the carriage 63.

  The ink cartridge 65 has an air opening communicating with the atmosphere upward, a supply opening supplying ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body. Thus, the ink supplied to the inkjet head is maintained at a slight negative pressure. Further, although the recording head 64 of each color is used here as the recording head, a single head having nozzles for ejecting ink droplets of each color may be used.

  Here, the carriage 63 is slidably fitted to the main guide rod 61 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 62 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 63 in the main scanning direction, a timing belt 70 is stretched between a driving pulley 68 and a driven pulley 69 that are rotationally driven by a main scanning motor 67, and the timing belt 70 is moved to the carriage 63. The carriage 63 is reciprocally driven by forward and reverse rotations of the main scanning motor 67.

  On the other hand, in order to convey the paper 53 set in the paper feeding cassette 54 to the lower side of the recording head 64, the paper feeding roller 71 and the friction pad 72 for separating and feeding the paper 53 from the paper feeding cassette 54 and the paper 53 are guided. A guide member 73 for conveying, a conveyance roller 74 for reversing and conveying the fed paper 53, a conveyance roller 75 pressed against the peripheral surface of the conveyance roller 74, and a feeding angle of the paper 53 from the conveyance roller 74 are defined. A tip roller 76 is provided. The transport roller 74 is rotationally driven by a sub-scanning motor 77 through a gear train.

  A printing receiving member 79 is provided as a paper guide member for guiding the paper 53 fed from the transport roller 74 below the recording head 64 corresponding to the range of movement of the carriage 63 in the main scanning direction. A conveyance roller 81 and a spur 82 that are rotationally driven to send the paper 53 in the paper discharge direction are provided downstream of the printing receiving member 79 in the paper conveyance direction. A roller 83 and a spur 84, and guide members 85 and 86 that form a paper discharge path are disposed.

  At the time of recording, the recording head 64 is driven according to the image signal while moving the carriage 63, thereby ejecting ink onto the stopped paper 53 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 53 reaches the recording area, the recording operation is terminated and the paper 53 is discharged.

  In addition, a recovery device 87 for recovering defective ejection of the recording head 64 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 63. The recovery device 87 includes a cap unit, a suction unit, and a cleaning unit. The carriage 63 is moved to the recovery device 87 side during printing standby, and the recording head 64 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  When a discharge failure occurs, the discharge port (nozzle) of the recording head 64 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with a suction unit through the tube. Etc. are removed by the cleaning means, and the ejection failure is recovered. The sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, since this inkjet recording apparatus is equipped with the inkjet head embodying the present invention, an image having a good gradation with little graininess can be obtained, the printing speed is high, and the inkjet recording apparatus is small. It is feasible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically illustrating a main part of a recording head according to a first embodiment of the present invention. FIG. 1A is a view of a surface on which a discharge port of a recording head is formed, and FIG. It is sectional drawing of the main scanning direction of 1 (A). FIGS. 2A and 2B are diagrams schematically illustrating a main part of a recording head according to a second embodiment of the present invention, in which FIG. 2 (A) is a cross-sectional view across a discharge port with a large opening diameter, and FIG. 2 (C) is a cross-sectional view across a discharge port with a small opening diameter in FIG. 2 (A). FIGS. 3A and 3B are diagrams schematically illustrating a main part of a recording head according to a third embodiment of the present invention, in which FIG. 3A is a view of the surface of the recording head on which the discharge port is formed, and FIG. 3 (A) is a cross-sectional view across a discharge port with a large opening diameter, and FIG. 3 (C) is a cross-sectional view across a discharge port with a small opening diameter in FIG. 3 (A). It is a perspective view which shows the head cartridge of Example 4 of this invention. It is a principal part perspective view which shows the inkjet recording device of Example 5 of this invention. It is a side view of the mechanism part of the inkjet recording device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording head, 2 (2-1, 2-2) ... Heating resistance element (energy conversion element), 3 ... Substrate, 4 (4-1, 4-2) ... Discharge port, 5 ... Orifice plate, 6 ... Drive circuit, 7 ... contact pad, 8 ... wiring, 9 ... ink supply port, 10 ... ink flow path, 11 ... common liquid chamber, 24Bk, 25Y, 26M, 27C, 34Bk, 35Y, 36M, 37C ... discharge port array, DESCRIPTION OF SYMBOLS 41 ... Head cartridge, 42 ... Recording head, 51 ... Recording apparatus main body, 52 ... Printing mechanism part, 53 ... Paper, 54 ... Paper feed cassette, 55 ... Manual feed tray, 56 ... Discharge tray, 61 ... Main guide lock 62 ... Subordinate Guide rod, 63 ... carriage, 64 ... recording head, 65 ... ink cartridge, 67 ... main scanning motor, 68 ... drive pulley, 69 ... driven pulley, 70 ... timing belt, 71 ... feed roller, DESCRIPTION OF SYMBOLS 2 ... Friction pad, 73 ... Guide member, 74 ... Conveyance roller, 75 ... Conveyance roller, 76 ... End roller, 77 ... Sub-scanning motor, 79 ... Printing receiving member, 81 ... Conveyance roller, 82 ... Spur, 83 ... Exhaust Paper roller, 84 ... spur, 85, 86 ... guide member, 87 ... recovery device.

Claims (7)

A configuration in which at least two types of ejection port arrays having ejection ports with different ejection port diameters are used to perform dot diameter control, a plurality of first ejection ports that eject a predetermined volume of recording liquid, and the predetermined volume A plurality of second ejection ports for ejecting a small volume of recording liquid, ejection energy generating means for ejecting the recording liquid corresponding to each of the first and second ejection ports, and the first and second recording liquids. In a recording head having a liquid supply path for supplying to a discharge port,
The recording head, wherein the first discharge port is a discharge port for discharging a recording liquid having a viscosity higher than that of the recording liquid discharged from the second discharge port.   The diameter of the first ejection port and the energy generated by the ejection energy generating means for ejecting the recording liquid from the first ejection port are the same as the diameter of the second ejection port and the recording liquid from the second ejection port. The recording head according to claim 1, wherein each of the recording heads is larger than energy generated by the discharge energy generating means for discharging.   The recording head according to claim 1, wherein a recording liquid of 4 mPa · s or more is discharged from at least the first discharge port.   The recording head according to claim 1, wherein a recording liquid containing a pigment as a component is discharged from the first and second discharge ports.   The recording head according to claim 1, wherein the discharge energy generating unit includes an electrothermal conversion element that utilizes a phase change caused by film boiling of a liquid using a heating resistor.   6. A head cartridge in which a liquid discharge head for discharging a liquid and a recording liquid tank for supplying a recording liquid to the liquid discharge head are integrated, wherein the liquid discharge head is the recording head according to claim 1. A head cartridge characterized by that.   A recording apparatus including a liquid discharge head for discharging a liquid, wherein the liquid discharge head is the recording head according to claim 1 or the head cartridge according to claim 6. apparatus.

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