JP3104070B2 - Inkjet recording head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head, and more particularly to an improvement in a supply path connecting an ink supply chamber and a pressure chamber.

[Conventional technology]

In order to meet the high printing quality required for the on-demand type ink jet recording apparatus, it is necessary to further increase the nozzle density. For that purpose, for example,
As disclosed in Japanese Patent Publication No. 172, an ink jet recording head has been proposed in which a plurality of ink chambers are alternately arranged on both sides of a nozzle row formed on a common substrate to increase the density. Further, in order to form this type of recording head at low cost, means for forming a substrate from a polymer resin material has been adopted.

By the way, in order to obtain high print quality with a high-density ink jet recording head, the ink enters a pressure chamber via a supply path from an ink supply chamber, is pressurized in the pressure chamber, and is ejected from a nozzle communicating with one end of the pressure chamber. It is required that the series of ink behavior, that is, the ink flying speed, the flying direction, the amount of ink per dot, and the like have no individual variations. Factors that greatly affect the variation in the ink behavior are variations in the shape and size of the supply path corresponding to the inlet of the pressure chamber and the shape and size of the nozzle corresponding to the outlet. It has been experimentally confirmed that if the variation of the cross-sectional area of the supply path and the nozzle is not more than ± 15%, the print quality can be ensured even if other portions vary.

If this is replaced with the dimensional accuracy of each part, the width and depth of the supply path with a rectangular cross section are ± 2.5 μm for about 40 μm each, and the supply path and nozzle with a circular cross section are ± 2.5 μm for a diameter of about 40 μm.
become. However, in reality, it is difficult to mold such fine dimensions with high precision by an injection molding method of a polymer resin material.

Further, in order to form fine dimensions with high precision, Japanese Patent Application Laid-Open
As shown in Japanese Patent No. 294047, there is a method of processing all the ink supply chambers, pressure chambers, supply paths, and nozzles with a laser beam, but this requires a lot of man-hours and is impractical.

On the other hand, a method of processing only the supply path with a laser is conceivable. FIG. 4 shows a head made by the inventor. The second substrates 8 and 10 are joined to the substrate 1 provided with the pressure chamber 4 so as to form a closed channel system. A nozzle plate 9 on which a nozzle 6 is formed is joined to the ink ejection side. The supply path 3 is formed on the inflow side of the pressure chamber 4 by laser processing. In addition, the second corresponding to the pressure chamber
The piezoelectric element 7 is provided on the substrate 8.

[Problems to be solved by the invention]

However, when the present inventor performed a printing test with the head having this configuration, many ejection failures occurred. The analysis revealed that the supply path 3 was clogged with dust 11.
When a hole is formed with a laser, the cross-sectional area on the incident side of the laser beam is A1 and that on the emitting side is A2, the relationship is A1> A2. In this head, a laser beam is incident from the ink supply chamber 2 side to form the supply path 3, so that the cross-sectional area on the ink supply chamber 2 side is widened, and as shown in FIG. 4, dust is easily clogged and easily fixed. It has a shape.

In addition, since there is a point 13 where the flow stagnates at the junction between the supply path 3 and the pressure chamber 4, there is a problem that the stagnant air bubbles cannot be easily removed there.

Therefore, the present invention solves such a problem, and an object of the present invention is to form a supply path shape by laser processing that is less likely to cause dust clogging and that is less likely to retain bubbles.

[Means for solving the problem]

The present invention relates to an ink jet recording head including a pressure chamber communicating with a nozzle, and an ink supply chamber for supplying ink to the pressure chamber via a hole-shaped supply path, wherein the pressure chamber, the supply path, and the ink supply chamber are high. The hole-shaped supply passage formed of a molecular resin is formed by irradiating a laser beam from the pressure chamber toward the ink supply chamber.

Further, in such an ink jet recording head, the hole-shaped supply path has a tapered shape expanding from the ink supply chamber toward the pressure chamber. Further, in such an ink jet recording head, the supply path length is 20 μm.
It is characterized in that it is not less than 1 μm.

Further, according the ink jet recording head, a supply chamber side cross-sectional area S1 and the pressure chamber side cross-sectional area S2 of the supply path is the S1 <S2, and that satisfy the relationship of ^{100μm 2 <S1 <S2 <50000μm} 2 Features.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an example of a mold structure for forming a head substrate.

The head substrate 1 is integrally formed of a polymer resin material injected and injected between the fixed mold plate 19 and the movable mold plate 20.

The fixed side mold plate 19 used for the molding has a molding convex portion 14 corresponding to the pressure chamber 4 of the head substrate 1 in a cavity portion thereof. Further, a pin 15 for forming a through hole 5 for communicating with the nozzle 6 is provided at one end of the pressure chamber forming projection 14. On the other hand, the movable mold plate 20 is provided with a molding projection 12 corresponding to the ink supply chamber 2 of the head substrate 1 in a cavity portion thereof.
Further, a support hole 21 at the tip of the pin 15 is formed in a portion facing the pin 15 for forming the through hole 5. In the drawing, reference numeral 22 denotes a runner portion, 23 denotes a gate portion, and 24 denotes an ejector pin.

The runner part 22 is provided between the two mold plates 19 and 20 thus configured.
When the above-mentioned polymer resin material is injected and injected through the gate portion 23, the ink supply chamber 2 is provided on one surface, the pressure chamber 4 is provided on the other surface, and the nozzle plate 7 is provided at one end of the pressure chamber 4 on one side. The head substrate 1 having the through holes 5 for communicating with the provided nozzles 6 is formed.

FIG. 2 shows a step of forming a supply path to the head substrate 1 thus formed. The head substrate 1 formed by the above-described process is fixed with the surface on which the ink supply chamber 2 is formed facing up, and is irradiated with a laser beam L from one end of the pressure chamber 4 toward the ink supply chamber 2. The supply path 3 is formed.

The laser beam generator 40 used for this is a high-energy photon in the ultraviolet region required for directly breaking chemical bonds, having an oscillation wavelength of 193 to 351 nm using ArF, KrF, XeCl, XeF, or the like as a laser catalyst. An excimer laser device that can oscillate with high intensity is preferable. The laser beam L output from the device 40 is converted into an image mask 41 and a condenser lens.
The required supply path 3 is formed by using 42 to converge on the connection between the ink supply chamber 2 and the pressure chamber 4 on the head substrate 1.

 FIG. 3 is a sectional view of the formed supply path 3.

The head substrate 1 is actually made of polycarbonate.
Is formed by an injection molding method, and a laser beam having an energy density of 6.0 J / cm ² is irradiated on a connection portion between the ink supply chamber 2 and the pressure chamber 4 using a condenser lens 42 having a reduction ratio of 8. A supply path 3 having a hole diameter of 40 μm, a depth of 120 μm, and a taper angle θ of about 2 degrees could be formed in 3 seconds per supply path at 200 Hz with about 600 shots.

If necessary, the head substrate 1 and the laser beam device 40
Of the supply paths 3 on the head substrate 1 while sequentially moving either one of them in accordance with the arrangement of the supply paths 3.
To form

When the hole serving as the supply path 3 is formed by the above-described method, if the length of the hole is less than 20 μm, the resin cannot be filled in the mold and the substrate cannot be formed. Further, when the length exceeds 1 mm, it is necessary to irradiate 1000 or more laser beams in order to form a hole with a laser, which is a problem from the viewpoint of cost and laser durability. For these reasons, the length of the holes should be between 20 μm and 1 m
The range of m is preferred.

When the sectional area of the supply path 3 on the ink supply chamber 2 side is S1, and the sectional area on the pressure chamber 4 side is S2, the relationship between S1 and S2 is S1 <S2.
Becomes Here, in order to generate pressure in the pressure chamber 4, S
1, S2 was not satisfied with an arbitrary value. According to the experiment of the present inventors, it was confirmed that S1 needs to have a diameter of 10 μm or more in the case of a circular cross section, and that S2 must have a diameter of 250 μm or less to eject droplets. When this is expressed by a mathematical formula, approximately 100 μm ² <S1 <S
2 <5000 μm ² .

〔The invention's effect〕

The present invention relates to an ink jet recording head including a pressure chamber communicating with a nozzle, and an ink supply chamber for supplying ink to the pressure chamber via a hole-shaped supply path, wherein the pressure chamber, the supply path, and the ink supply chamber are high. Factors that have a large effect on variations in ink behavior because the hole-shaped supply path is formed by irradiating laser beam light from the pressure chamber to the ink supply chamber side, which is formed by molecular resin. The variation between the cross-sectional area of the supply path corresponding to the inlet of the pressure chamber and the cross-sectional area of the nozzle corresponding to the outlet can be suppressed within an allowable range, and at the same time, the nozzle expands from the ink supply chamber toward the pressure chamber. It can be easily and quickly formed into a tapered shape that does not easily clog dust in the supply path,
This has the effect that an ink jet head with a smooth flow of ink and no stagnation of bubbles can be provided at low cost and with high accuracy.

In addition, in the ink jet recording head, since the supply path length is not less than 20 μm and not more than 1 mm, the head substrate can be more easily formed by injecting and injecting the polymer resin into the template, and the laser beam This has the effect that the supply path can be formed at high speed by irradiation.

Further, according the ink jet recording head, a supply chamber side cross-sectional area S1 and the pressure chamber side cross-sectional area S2 of the supply path is the S1 <S2, and by satisfy the relationship of ^{100μm 2 <S1 <S2 <50000μm} 2 , Dust is hard to clog in the supply path,
This has the effect of providing an ink jet head with a smooth ink flow, no stagnation of air bubbles, and stable ejection characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a mold structure for forming a flow path substrate used in the present invention. FIG. 2 is a sectional view showing an embodiment of the present invention. FIG. 3 is an enlarged sectional view of a supply path in the embodiment. FIG. 4 is a sectional view showing the structure of a conventional head. DESCRIPTION OF SYMBOLS 1 ... Head substrate 2 ... Ink supply chamber 3 ... Supply path 4 ... Pressure chamber 5 ... Through-hole 6 ... Nozzle 7 ... Piezoelectric element 8, 10 ... Second substrate 9 ... Nozzle plate 11 ... … Dust 19… fixed-side mold plate 20… movable-side mold plate 40… laser beam generator 41… mask 42… condensing lens

Claims (4)

(57) [Claims] 1. An ink jet recording head comprising: a pressure chamber communicating with a nozzle; and an ink supply chamber for supplying ink to the pressure chamber via a hole-shaped supply path, wherein the pressure chamber, the supply path, An ink supply chamber formed of a polymer resin, and the hole-shaped supply path formed by irradiating a laser beam from the pressure chamber toward the ink supply chamber; . 2. The ink jet recording head according to claim 1, wherein said hole-shaped supply path has a tapered shape expanding from said ink supply chamber toward said pressure chamber. 3. The ink jet recording head according to claim 1, wherein said supply path length is not less than 20 μm and not more than 1 μm. 4. A sectional area S1 on the supply chamber side and a sectional area S2 on the pressure chamber side of the supply path are S1 <S2, and 100 μm ² <S1 <S2 <500.
^3. The ink jet recording head according to claim ^{2, wherein} a relationship of 00 μm ² is satisfied.