JP2003127352A - Ink jet printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printing device which realizes a high density and high speed printing so as to obtain a photo-like image quality without using a long line head. SOLUTION: The ink jet printing device is provided with a plurality of head units 1 to 4 constituted of a plurality of YMCK line heads in which a plurality of discharge nozzles discharging ink is arranged at predetermined spaces in a width direction H of a recording medium S. Overlapping of the head units in the width direction of the recording medium is adjusted by moving the head units in the width direction of the recording medium, and a feeding speed in feeding the recording medium in the feeding direction F orthogonal to the width direction is adjusted depending upon a state of the respective head units being overlapped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing apparatus having a line head, and more particularly, to an ink jet printing apparatus capable of obtaining photo-like image quality and capable of high speed printing.

[0002]

2. Description of the Related Art Conventionally, an ink jet printer using a line head which extends in the main scanning direction and is fixed is known. In this case, a long line head may be necessary in order to correspond to the width of the paper on which the image is recorded, but with a long line head, it is difficult to increase the density of the nozzles due to manufacturing processing problems. In addition, it is difficult to improve the image quality due to the occurrence of deflection.

Further, since the line head does not scan, the dot density in the width direction of the recording medium such as paper cannot be made higher than the density of the ejection nozzles. Therefore, in such an inkjet printer, at least 600 dp
It is difficult to obtain a photo-like image quality that requires a recording density of about i. Further, increasing the density of the discharge nozzles in the width direction of the recording medium is apt to cause clogging, which is a serious problem particularly in a usage environment in a vendor lab or the like which is exposed to dust from the outside air.

[0004]

SUMMARY OF THE INVENTION The present invention provides an ink jet printing apparatus capable of achieving high density and high speed printing capable of obtaining photo-like image quality without using a long line head. The purpose is to do.

[0005]

In order to achieve the above object, an ink jet printing apparatus according to the present invention comprises a plurality of YMCKs in which a plurality of ejection nozzles for ejecting ink are arranged at predetermined intervals in the width direction of a recording medium. Head moving means for adjusting the overlap in the width direction of the plurality of head units by moving the plurality of head units in the width direction of the recording medium, comprising a plurality of head units configured of line heads, And a transport speed adjusting unit for adjusting a transport speed when transporting the recording medium in a transport direction orthogonal to the width direction, based on an overlapping state of the head units.

According to this ink jet printing apparatus, the plurality of head units can be moved in the width direction of the recording medium to change the arrangement of the plurality of head units. In addition to being compatible with a recording medium, the transport speed of the recording medium in the sub-scanning direction is adjusted based on the overlapping state of the head units, and for example, when recording is performed on a relatively narrow recording medium with at least two overlapping head units, It can be printed at a high conveyance speed or can be printed at a high density so as to obtain a photo-like image quality.

By adjusting the overlap of the plurality of head units based on the width of the recording medium, it becomes possible to print according to recording media of various sizes having different width dimensions.

In this case, the plurality of head units are
At the time of movement by the head moving means, the recording medium having a relatively wide width is arranged to have a step in the width direction, and the recording medium having a relatively narrow width is substantially overlapped in the width direction. Will be placed.

Further, high-speed printing is possible by configuring the carrying speed so that it can be set faster in inverse proportion to the degree of overlap of the plurality of head units.

In this case, the overlapping state of at least two head units is adjusted so that the respective discharge nozzles are at the same position in the width direction, so that high-speed printing is possible.

Further, the overlapping state of at least two head units is adjusted so that the ejection nozzle of the other head unit is positioned within the nozzle interval of one head unit in the width direction, thereby Since ink can be ejected from the ejection nozzles of the other head unit within the nozzle interval of the head unit, it is possible to perform printing with a higher density than the writing density (dot density) corresponding to the nozzle interval.

Further, when at least two of the head units are overlapped with each other, high-density printing or high-speed printing can be selected so that they can be appropriately selected and switched as needed. It is very convenient.

The recording medium has a thickness of 170 μm.
Since the paper is laminated with resin on at least the image recording surface side as described above, it is possible to realize a photo-like glossy image quality. Further, by using a pigment ink as the ink, it is possible to realize a more photo-like glossy image quality.

In the ink jet recording medium of the present invention, it is preferable to use a paper support in which both sides of the base paper support are laminated with polyethylene, because the recorded image is close to the photographic quality and a high quality image can be obtained at low cost. Particularly preferred. A paper support laminated with such polyethylene will be described below.

The base paper used for the paper support is mainly made of wood pulp, and if necessary, synthetic paper such as polypropylene or synthetic fiber such as nylon or polyester is used in addition to wood pulp. As wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP and NUKP can be used, but LBKP, NB with a large amount of short fibers
It is preferable to use more SP, LBSP, NDP, and LDP.
However, the ratio of LBSP and / or LDP is 10 mass% or more, 70
It is preferably not more than mass%.

Chemical pulp (sulfate pulp or sulfite pulp) having few impurities is preferably used as the above-mentioned pulp, and a pulp having a whiteness improved by bleaching is also useful.

In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strengthening agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, A water retention agent such as polyethylene glycol, a dispersant, a softening agent such as quaternary ammonium, and the like can be added as appropriate.

The freeness of the pulp used for papermaking is preferably 200 to 500 ml according to the CSF standard, and the fiber length after beating is the mass% of the 24 mesh residue defined in JIS-P-8207. 42
The sum with the mass% of the mesh residue is preferably 30 to 70%.
The mass% of the 4-mesh residue is preferably 20 mass% or less.

The thickness of the base paper is preferably 140 μm to 350 μm, more preferably 160 μm to 250 μm.

The base paper can be given a high smoothness by calendering at the papermaking stage or after papermaking. Base paper density is 0.
7 to 1.2 g / m2 (JIS-P-8118) is common. Further, the stiffness of the base paper is preferably 20 to 200 g under the conditions specified in JIS-P-8143.

A surface sizing agent may be applied to the surface of the base paper, and as the surface sizing agent, the same sizing agent as that which can be added to the base paper can be used.

The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS-P-8113.

The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or
Or high density polyethylene (HDPE) but other LLDP
Some E and polypropylene can also be used.

In particular, the polyethylene layer on the side of the void layer is preferably one in which rutile or anatase type titanium oxide is added to polyethylene so as to improve opacity and whiteness, as is widely used in photographic printing paper. The content of titanium oxide is usually 3 to 20% by mass, preferably 4 to 13% by mass, based on polyethylene.

The polyethylene-coated paper may be used as a glossy paper, or may be subjected to so-called patterning treatment when polyethylene is melt-extruded on the surface of the base paper for coating, and a matte surface or a silk surface obtained by ordinary photographic printing paper. Surface-formed articles can also be used in the present invention.

The amount of polyethylene used on the front and back of the base paper is selected so as to optimize curling under low and high humidity after providing the void layer and the back layer, but the polyethylene layer on the void layer side is usually 20. -40 μm, and the back layer side is 10-30 μm.

Further, the polyethylene-coated paper support preferably has the following characteristics. 1. Tensile strength: The strength specified by JIS-P-8113 is preferably 2 to 30 kg in the longitudinal direction and 1 to 20 kg in the lateral direction. 2. Tear strength is defined by JIS-P-8116. 10 to 200 g in the longitudinal direction and 20 to 200 g in the lateral direction are preferred. 3. Compressive modulus ≥ 98.1 MPa 4. Surface Beck smoothness: 2 under the conditions specified in JIS-P-8119.
0 seconds or more is preferable as a glossy surface, but it may be less than this for so-called molded products. 5. Surface roughness: The surface roughness specified in JIS-B-0601 is the maximum height per standard length 2.5 mm. The thickness is preferably 10 μm or less. 6. Opacity: 80% or more, particularly 85 to 98% is preferable when measured by the method specified in JIS-P-8138 7. Whiteness: JIS-Z-8729 L *, a *, b * specified by L * = 80
~ 95, a * = -3 to +5, b * = -6 to +2 8. Surface gloss: 60-degree specular gloss of 10-95% specified in JIS-Z-8741 9. Clark rigidity: A support having a Clark rigidity of 50 to 300 cm2 / 100 in the recording paper transport direction is preferable. 10. Water content of inner paper: usually 2 to 100 relative to inner paper. mass%,
Preferably 2 to 6% by mass

The method of coating various hydrophilic layers, such as a void layer and an undercoat layer of the recording medium, which are appropriately provided as necessary, on the support in the present invention can be appropriately selected from known methods. A preferred method is obtained by applying a coating solution forming each layer on a support and drying. In this case, two or more layers can be coated at the same time, and in particular, simultaneous coating in which all hydrophilic binder layers need to be coated once is preferable.

As a coating method, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

The ink solvent that can be used in the present invention is preferably a water-soluble organic solvent. Specifically, alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pen) are used. Tanol, hexanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, Glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (eg ethylene glycol mono) Chill ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate , Triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol dimethyl ether Etc.),
Amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyl Diethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc., sulfoxides (eg, dimethyl sulfoxide), sulfones (eg,
Sulfolane etc.), sulfonates (eg 1-butanesulfonic acid sodium salt etc.), urea, acetonitrile, acetone and the like. These ink solvents may be used alone or in combination.

In the present invention, the ink must contain a surfactant in order to improve the dispersion stability of the pigment. Surfactants preferably used in the ink of the present invention include dialkyl sulfosuccinates, alkylnaphthalene sulfonates, anionic surfactants such as fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers. , Acetylene glycols, nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments,
Polycyclic pigments such as dioxane pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, dye lakes such as basic dye type lakes and acid dye type lakes, nitro pigments, nitroso pigments, aniline black, daylight fluorescence Examples include organic pigments such as pigments and inorganic pigments such as carbon black. Specific organic pigments are exemplified below.

As the pigment for magenta or red,
C. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16,
C. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57:
1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139,
C. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I.
I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12,
C. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I.
I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I.
Pigment Yellow 138 and the like.

As a pigment for green or cyan,
C. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3,
C. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

In the present invention, a pigment dispersant may be used if necessary, and examples of the pigment dispersant that can be used include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, and sulfosuccinates. , Naphthalene sulfonate, alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide,
Activator such as amine oxide, or two kinds selected from styrene, styrene derivative, vinylnaphthalene derivative, acrylic acid, acrylic acid derivative, maleic acid, maleic acid derivative, itaconic acid, itaconic acid derivative, fumaric acid, fumaric acid derivative Examples thereof include block copolymers, random copolymers and salts of the above monomers.

Various methods such as ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill and paint shaker can be used for dispersing the pigment. Using a centrifugal separator for the purpose of removing coarse particles of the pigment dispersion of the present invention,
It is also preferable to use a filter.

The average particle size of the pigment dispersion used in the ink according to the present invention is preferably 10 nm or more and 200 nm or less, more preferably 10 nm or more and 100 nm or less, and 10 nm or more and 50 n or less.
It is more preferably m or less. The average particle size of the pigment dispersion is 100 n
If it exceeds m, the glossiness of the image recorded on the glossy media deteriorates, and the transparency of the image recorded on the transparency medium deteriorates significantly. If the average particle size of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.

The particle size of the pigment dispersion can be measured by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain it by performing particle image photography with a transmission electron microscope on at least 100 particles and performing statistical processing on this image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). It is possible.

The ink according to the present invention may contain a latex. The latex in the present invention refers to polymer particles in a dispersed state in a medium. Examples of the type of polymer include styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, acrylic ester copolymer, polyurethane, silicone-acrylic copolymer, acrylic modified fluororesin, and the like. Acrylate esters, polyurethanes and silicone-acrylic copolymers are preferred.

A low molecular weight surfactant is generally used as an emulsifier used in the production of latex, but in this case, a high molecular weight surfactant (for example, a solubilizing group is graft-bonded to a polymer). Type or a block polymer type in which a part having a solubilizing group and an insoluble part are linked) is used as an emulsifier, or the emulsifier is not used by directly bonding the solubilizing group to the central polymer of the latex. Some latex is dispersed. The latex in which a high molecular weight surfactant is used as the emulsifier and the latex in which the emulsifier is not used are called soap-free latex. The latex used in the present invention may be any type or form of emulsifier,
It is more preferable to use a soap-free latex that is excellent in ink storage stability.

Recently, in addition to the latex in which the central polymer is uniform, there is also a core / shell type latex in which the composition is different between the central portion and the outer edge portion of the polymer particles, and this type of latex is also preferably used. it can.

In the present invention, the average particle size of the latex is 150 nm.
The following is preferable, and 50 nm or less is more preferable. The average particle size of the latex can be easily measured by using a commercially available measuring device using a light scattering method or a laser Doppler method.

In the present invention, the solid content of the latex is 0.1% by weight or more and 10% by weight or less, particularly 0.3% by weight or more and 5% by weight or less, based on the total weight of the ink. If the addition amount is less than 0.1% by weight, it is difficult to exert a sufficient effect on water resistance, and if the addition amount exceeds 10% by weight, ink viscosity and pigment dispersion particle size tend to increase over time, and ink storage stability is increased. Problems often arise.

In the ink according to the present invention, an electric conductivity adjusting agent may be used. For example, inorganic salts such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate and sodium chloride, and aqueous amines such as triethanolamine may be used. Can be mentioned.

In addition to the above, the ink according to the present invention contains a preservative,
A fungicide, a viscosity modifier, etc. may be contained as necessary.

The inkjet head used in the inkjet printing apparatus of the present invention may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electric-heat conversion method (for example, a thermal type Inkjet type,
Bubble jet (registered trademark) type, etc., electrostatic attraction method (for example, electric field control type, slit jet type, etc.), discharge method (for example, spark jet type, etc.) and the like can be mentioned as specific examples. Either ejection method may be used.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view schematically showing a main part of an inkjet printer according to an embodiment of the present invention, and FIG. 2 is a plan view showing a drive system for adjusting the position of each head unit of the inkjet printer of FIG. FIG. 3 is a block diagram showing the control system of the inkjet printer of FIG.

As shown in FIG. 1, the ink jet printer according to the present embodiment has the first to fourth head units 1, 1.
2, 3 and 4 and head movement drive units 11a, 12a, 13a, 14 including motors for adjusting the positions of the first to fourth head units 1 to 4 in the horizontal direction H in the drawing, respectively.
a, rotary shafts 11, 12, 13, and 14 that are rotationally driven by the head movement drive units 11a to 14a to move the head units 1 to 4 in the horizontal direction H, respectively. The conveyance roller 5 for conveying the recording medium S in the lower conveyance direction F in FIG. 1 and the disc-shaped scale 8a connected to rotate together with the rotation shaft 5a of the conveyance roller 5 conveys the recording medium S. A transport detection encoder module 8 for detecting the position.

The first head unit 1 has a large number of ejection nozzles (for example, 1e, 1f, 1g, 1 in FIG. 5) so as to extend in the width direction of the sheet-shaped recording medium S (horizontal direction H in FIG. 1).
(h, ...) Are arranged in a line at a predetermined interval p, and the line heads 1a, 1b, 1c, 1d of YMCK are integrated. Similarly, the second head unit 2
YMC in which a large number of discharge nozzles are arranged in a line at a predetermined interval p
The K line heads 2a, 2b, 2c, and 2d are integrally formed, and the third head unit 3 includes YMCK line heads 3a, 3b, and 3c in which a large number of ejection nozzles are arranged in a line at a predetermined interval p. 3d is integrally formed, and the fourth
The head unit 4 of the YMCK line heads 4a, 4b has a large number of ejection nozzles arranged in a line at a predetermined interval p.
4c and 4d are integrated.

In each of the head units 1 to 4 shown in FIG. 1, each line head extends orthogonal to the transport direction F of the recording medium S and extends in the lateral direction H in parallel with the recording medium S. They are separated by a fixed amount. Each line head 1a-1
Each of the discharge nozzles d, 2a to 2d, 3a to 3d, and 4a to 4d is composed of a piezo element that is sheared and deformed by the application of a voltage, and is sheared and deformed in accordance with the voltage level of the input drive signal. By ejecting color inks to form dots, an image is written on the recording medium S to form a color image.

As shown in FIGS. 1 and 2, each head unit 1
On each of the upper surfaces of 4 to 4, fixing portions 11b to 14b having screw holes formed therein are fixed so that the rotating shafts 11 to 14 screwed in a spiral shape on the outer peripheral surface are screwed. . By rotating the rotating shafts 11 to 14 by the head movement driving units 11a to 14a, the fixed units 11
Each of the head units 1 to 4 is in the horizontal direction H via b to 14b.
Move to. Further, the number of rotations of the rotary shafts 11 to 14 is proportional to the amount of movement of each head unit 1 to 4. In this way, the head units 1 to 4 move in the lateral direction H independently of each other, and the respective positions can be adjusted based on the rotation speeds of the rotary shafts 11 to 14, respectively.
The arrangements of 4 can be changed to various patterns.

Further, as shown in FIG. 1, the recording medium S is sandwiched between the conveying roller 5 longer than the width of the recording medium S and the plurality of pressure contact rollers 7, and is urged by a spring (not shown) or the like. The recording medium S is pressed against the transport roller 5 by urging the pressure roller 7 toward the transport roller 5 by the plurality of biasing members 7 a. When the rotation shaft 5a is rotated by the rotation of the transport motor 6 and the transport roller 5 is rotated, the recording medium S is transported in the transport direction F by the frictional force between the transport roller 5 and the recording medium S.

As shown in FIG. 3, the ink jet printer of FIG. 1 serves as a control system, and includes a control unit 20 for controlling the entire apparatus and an image memory 21 for storing image data signals input from an external apparatus such as a personal computer. Based on an image data signal from the operation panel 22, which enables the user to select and input various information such as the size of the recording medium, the conveyance speed, and the writing density, and the head units 1 to 1 based on the image data signal from the image memory 21. 4 head drive circuit 23 for generating a drive signal for driving each line head so that ink is ejected from each line head.

The controller 20 stores the origin position and the number of revolutions of each head unit 1 to 4 in its memory, and the head movement drive units 11a to 14a based on the stored information.
It is possible to adjust the respective positions of the head units 1 to 4 by controlling the rotation speed of the recording medium S, and to adjust the transport speed of the recording medium S in the transport direction F by controlling the rotation speed of the transport motor 6. Has become.

Next, the operation of the ink jet printer shown in FIGS. 1 to 3 will be described with reference to FIGS. Figure 4
5A, 5B, and 5C are plan views showing the arrangement of each head unit that is changed in three ways according to the width size of the recording medium, and FIGS. 5A, 5B, and 5C. 10] is a plan view when the relative position of each discharge nozzle is changed in three ways.

Each recording medium has a thickness of at least 1.
The paper is 70 μm and at least the image recording surface side is laminated with resin, and pigment ink is used as the ink ejected from the ejection nozzles.

(1) Wide recording medium

As shown in FIG. 4A, when the image is recorded on the wide recording medium S1, the user designates the size of the recording medium from the operation panel 22, and the control unit 20 causes the head movement drive unit. 11a to 14a are respectively driven, first to fourth head units 1 to 4 are moved, and respective positions are adjusted so that an image can be formed on the entire width direction of the wide recording medium S1 as shown in FIG. 4A. To do. In this way, the head units 1 to 4 are arranged so as to have a step difference in the width direction H and are arranged so as not to overlap each other.

Next, the head drive circuit 23 sends a drive signal based on the image data signal to the head units 1 to 4 under the control of the control section 20 while timing the head units 1 to 4, and the respective line heads 1a to 1d, 2a to 2d and 3a. ~ 3d, 4
By ejecting YMCK ink from each of the ejection nozzles a to 4d, dots are formed and writing is performed in each row. The recording medium S is conveyed in the conveyance direction (sub-scanning direction) F by the conveyance roller 5 by the conveyance motor 6 at the timing of the end of this writing, and the conveyance position is detected by the conveyance detection encoder module 8, and the next writing position is detected. Then, the next line is written in the same manner to form a predetermined image on the recording medium S1. In this case, the writing (dot) density is determined by the arrangement density according to the interval p (FIG. 5) between the ejection nozzles of each line head.

(2) Medium width recording medium

As shown in FIG. 4B, in the case of recording an image on the medium width recording medium S2, similarly, the size of the recording medium is designated, and the control unit 20 causes the head movement drive unit 11a.
14a to move the first to fourth head units 1 to 4 so that the head units 1 and 2 overlap and the head units 3 and 4 overlap as shown in FIG. 4B, and the medium width recording medium S2 Each position is adjusted so that an image can be formed on the entire surface in the width direction. In this way, the head units 1 to 4 are arranged stepwise in the width direction H so that the two head units overlap each other, and the two head units are arranged to perform image formation in the same region.

The discharge nozzles of each line head are the discharge nozzles 1e of the line head 1a of the head unit 1.
1f, 1g, 1h, ..., And the discharge nozzles 2e, 2f, 2g, 2h, ... Of the line head 2a of the head unit 2.
.. and are in the same position in the width direction H (FIG. 5 (a))
(See the relative positions of the discharge nozzles of the line heads 1a and 2a). Similarly, the discharge nozzles 3e, 3f, 3g, 3h, ... Of the line head 3a of the head unit 3 and the discharge nozzles 4e, 4 of the line head 4a of the head unit 4.
f, 4g, 4h, ... Are at the same position in the width direction H (see the relative positions of the respective discharge nozzles of the line heads 3a and 4a in FIG. 5A). Further, other line heads 1b to 1d, 2b to 2d, 3b to 3 of the other head units.
The relative positions of d, 4b to 4d are also the same.

Next, the head drive circuit 23 sends a drive signal based on the image data signal to the head units 1 to 4 under the control of the control section 20 while timing the head units 1 to 4, and each line head 1a to 1d, 2a to 2d, 3a. ~ 3d, 4
By ejecting YMCK ink from each of the ejection nozzles a to 4d, dots are formed and writing is performed in each row. The recording medium S is conveyed in the conveyance direction (sub-scanning direction) F by the conveyance roller 5 by the conveyance motor 6 at the timing of the end of this writing, and the conveyance position is detected by the conveyance detection encoder module 8, and the next writing position is detected. Then, the next line is written in the same manner to form a predetermined image on the recording medium S1. When images are formed by the head units 1 to 4 in this manner, the head units 1 and 2
4A are located at the same position in the width direction H and the ejection nozzles of the head units 3 and 4 are located at the same position in the width direction H (see FIG. 5A), the writing speed is as shown in FIG. 2) compared with the case where the head units do not overlap each other as shown in FIG. Therefore, the control unit 20 doubles the conveyance speed of the recording medium S2 in the conveyance direction F to perform printing, and thus high-speed printing can be realized. The writing density is the same as that in FIG.

Next, the case where the relative position of each discharge nozzle is changed to improve the writing density in FIG. 4B will be described. That is, the discharge nozzle 2e of the line head 2a of the head unit 2 is located at a position approximately half the nozzle interval p between the discharge nozzles 1e and 1f of the line head 1a of the head unit 1 in the width direction H. The discharge nozzles 2f, 2g, 2h, ... Have the same relative position (see the relative positions of the discharge nozzles of the line heads 1a and 2a in FIG. 5B). Similarly, the discharge nozzles 3e, 3f, 3g, 3h of the line head 3a of the head unit 3 are ...
.., and the relative positions of the discharge nozzles 4e, 4f, 4g, 4h, ... Of the line head 4a of the head unit 4 are also approximately half the nozzle interval p in the width direction H (FIG. (Refer to the relative position of each discharge nozzle of the line heads 3a and 4a of b). Further, other line heads 1b to 1d, 2b to 2d, 3b to 3d, 4b to 4 of the other head units.
d is also in the same relative position.

When the image is formed by the head units 1 to 4 in which the relative positions of the discharge nozzles are adjusted as described above,
The ejection nozzles of the head units 1 and 2 are displaced from each other in the width direction H by approximately half the nozzle spacing p, and the ejection nozzles of the head units 3 and 4 are displaced from each other in the width direction H by approximately half the nozzle spacing p (FIG. 5). (See (b)), so the writing density is as shown in FIG.
This is twice as large as that in the case where there is no overlapping of the head units as in (a) (writing density determined by the interval p of the ejection nozzles). This enables high-density printing. Further, since the writing speed is the same as that in FIG. 4A, the conveying speed of the recording medium S2 is also the same.

In the arrangement of the head units 1 to 4 as shown in FIG. 4B, the selection of the high speed printing and the high density printing can be performed by the user designating on the operation panel 22 of FIG. By this control, the control unit 20 controls the head movement drive units 11a to 14a to adjust the positions of the head units 1 to 4 such that the relative positions of the ejection nozzles are as shown in FIG. 5A or 5B.

Further, in FIG. 4B, the head units 1 and 3 may be arranged to overlap each other and the head units 2 and 4 may be arranged to overlap each other. Alternatively, the head units 1 and 4 may overlap and the head units 2 and 3 may be arranged to overlap each other. You may arrange so that they may overlap. In the former case, when performing high-density printing, when the dots are formed close to the dots of the head units 1 and 3 and 2 and 4 at the interval p, the arrangement of FIG. Since there is a time lag and the ink easily dries, a higher quality image can be formed, which is preferable.

(3) Narrow recording medium

As shown in FIG. 4C, in the case of recording an image on the narrow recording medium S3, similarly, the size of the recording medium is designated, and the control unit 20 causes the head movement drive unit 11a.
14a to move the first to fourth head units 1 to 4, and as shown in FIG. 4C, the head units 1, 2, 3,
Adjust each position in the width direction H so that 4 overlaps,
An image can be formed on the entire width direction of the narrow recording medium S3.

As shown in FIG. 5A, the discharge nozzles of the line heads 1 to 4 are the discharge nozzles 1e, 1f, 1g, 1h, ... Of the line head 1a.
Discharge nozzles 2e, 2f, 2g, 2h, ..., Discharge nozzles 3e, 3f, 3g, 3h of the line head 3a.
., And the discharge nozzles 4e, 4f, 4 of the line head 4a
, g, 4h, ... Are at the same position in the width direction H.
Further, other line heads 1b to 1 of other head units
d, 2b to 2d, 3b to 3d, and 4b to 4d have the same relative position.

Next, the head drive circuit 23 sends a drive signal based on the image data signal to the head units 1 to 4 under the control of the control section 20 and the respective line heads 1a to 1d, 2a to 2d and 3a. ~ 3d, 4
By ejecting YMCK ink from each of the ejection nozzles a to 4d, dots are formed and writing is performed in each row. The recording medium S is conveyed in the conveyance direction (sub-scanning direction) F by the conveyance roller 5 by the conveyance motor 6 at the timing of the end of this writing, and the conveyance position is detected by the conveyance detection encoder module 8, and the next writing position is detected. Then, the next line is written in the same manner to form a predetermined image on the recording medium S1. When images are formed by the head units 1 to 4 in this manner, the head units 1 to 4
Since the respective ejection nozzles are located at the same position in the width direction H, the writing speed is four times that in the case where there is no overlapping of the head units as shown in FIG. Therefore, the control unit 20
Since printing is performed by adjusting the transport speed of the recording medium S2 in the transport direction F to four times, high-speed printing can be realized. The writing density is the same as in FIG. 4 (a).

Further, as shown in FIG. 5B, the respective ejection nozzles in the line heads 1a and 2a are displaced in the width direction H by approximately half of the nozzle interval p and the line heads 3a and 4a.
The respective ejection nozzles are arranged so as to be displaced in the width direction H by approximately half of the nozzle interval p, the line heads 1a and 3a are at the same position in the width direction H, and the line heads 2a and 4a are at the same position in the width direction H. By adjusting the positions of the head units 1 to 4 as shown in FIG. 4, the writing speed can be doubled and the transport speed can be doubled as compared with the case where there is no overlap of the head units in FIG. At the same time, the writing density is doubled. In this way, both high speed printing and high density printing can be realized.

Further, as shown in FIG. 5 (c), the discharge nozzles 2e, 3e, 4e of the line heads 2a, 3a, 4a are placed within a space p between the discharge nozzles 1e, 1f of the line head 1a.
4 are adjusted by adjusting the positions of the head units 1 to 4 so that they are located at substantially equal intervals in the width direction H, respectively.
The writing density is four times as high as that in the case of (a) where the head units do not overlap each other, and higher density printing can be realized. The conveyance speed of the recording medium S3 is the same as that in the case of FIG.

As described above, by changing the arrangement of the plurality of head units 1 to 4 according to the width dimension of the recording media S1 to S3 and adjusting the overlapping of the head units, it is possible to print on recording media of different sizes. The wide-width recording medium S1 can be printed by a relatively short line head, the medium-width recording medium S2 can be printed at high speed or high density, and the narrow-width recording medium S3 can be printed.
Can be printed at high speed and high density, or can be printed at higher speed or higher density. By such high-density image formation, a photo-like high-quality image can be realized, and image formation can be performed at high speed.

Further, the line heads 1 to 4 are not long so as to cover the width dimensions of the wide or medium width recording media S1 and S2, but short enough to cover the width dimensions of the narrow recording medium S3. Since the nozzles can be configured, it is possible to increase the density of nozzles, which was difficult to achieve with a long line head, and it is possible to suppress the occurrence of bending and achieve high image quality. Further, for narrow-width / medium-width recording media, the writing (dot) density can be improved without increasing the density of the nozzles of the line head, so that a photo-like high recording density of about 600 dpi or more is required. The image quality can be realized, the discharge nozzle is less likely to be clogged, and it can be used even in an environment such as a vendor lab that is exposed to dust from the outside air.

Further, since the pigment ink is printed on the resin-coated paper as the recording medium, it is possible to easily obtain a high-quality image which is glossy and photo-like.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to these.
Various modifications are possible within the scope of the technical idea of the present invention. For example, the number of head units may be 5 or more so that printing can be performed by adjusting the transport speed and the writing density in another stage, or 2 or 3 can be used to further simplify the structure. is there. Also, the size of the recording medium can be dealt with even if the size is further increased.

[0079]

According to the present invention, it is possible to provide an ink jet printing apparatus in which high density and high speed printing capable of obtaining photo-like high image quality can be realized without using a long line head. .

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a main part of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a plan view showing a drive system for adjusting the position of each head unit of the inkjet printer of FIG.

3 is a block diagram showing a control system of the inkjet printer of FIG. 1. FIG.

4A and 4B are plan views showing the arrangement of head units when printing on a wide recording medium in the inkjet printer of FIG. 1, and FIG. 4 is a plan view showing arrangement of head units when printing on a medium recording medium. FIG. 3B is a plan view showing the arrangement of the head units when printing on a narrow recording medium.

FIG. 5 is a plan view (a), (b) showing the case where the relative position of each discharge nozzle is changed in three ways in the inkjet printer of FIG. 1 by taking the line heads 1a to 4a as an example.
It is (c).

[Explanation of symbols]

1-4 head units 1a to 1d line heads 2a to 2d of head unit 1 line heads 3a to 3d of head unit 2 line heads 4a to 4d of head unit 3 line heads 1e to 1h line heads of head unit 4 1a Discharge nozzles 2e to 2h Discharge nozzles 3e to 3h of the line head 2a Discharge nozzles 4e to 4h of the line head 3a Discharge nozzles 5 of the line head 4a Conveying rollers 6 Conveying motors 11 to 14 Rotating shafts 11a to 14a Head movement driving unit 11b -14b Fixed part 20 Control part S Recording medium S1 Wide recording medium S2 Medium recording medium S3 Narrow recording medium p Nozzle spacing H Recording medium width direction, Lateral direction F Recording medium conveyance direction, Sub-scanning direction

Claims (9)

[Claims] 1. A head unit comprising a plurality of line heads in which a plurality of ejection nozzles for ejecting ink are arranged at predetermined intervals in the width direction of the recording medium, and the plurality of head units are provided in the recording medium. Head moving means for adjusting the overlap of the plurality of head units in the width direction by moving in the width direction, and a conveyance speed when the recording medium is conveyed in a conveyance direction orthogonal to the width direction. An inkjet printing apparatus further comprising: a conveyance speed adjusting unit for adjusting the head unit based on an overlapping state of the head units. 2. The inkjet printing apparatus according to claim 1, wherein the overlapping of the plurality of head units is adjusted based on the width of the recording medium. 3. The recording medium having a relatively narrow width and a plurality of head units arranged so as to have a step in the width direction with respect to a recording medium having a relatively wide width when moved by the head moving unit. The two are arranged so as to substantially overlap with each other in the width direction.
Alternatively, the inkjet printing apparatus described in 2. 4. The inkjet printing apparatus according to claim 1, wherein the conveyance speed can be set to be high in inverse proportion to the degree of overlap of the plurality of head units. 5. The overlapping state of at least two head units is adjusted so that the respective ejection nozzles are at the same position in the width direction. Inkjet printing device. 6. The overlapping state of at least two head units is adjusted such that the ejection nozzles of the other head unit are positioned within the nozzle spacing of one head unit in the width direction. The inkjet printing apparatus according to any one of claims 1 to 4. 7. The high density print or the high speed print can be selected when at least two of the head units are overlapped with each other, according to any one of claims 1 to 6. Inkjet printing device. 8. The inkjet printing apparatus according to claim 1, wherein the recording medium is a paper having a thickness of 170 μm or more and at least an image recording surface side thereof is laminated with a resin. . 9. The inkjet printing apparatus according to claim 8, wherein a pigment ink is used as the ink.