JPH1076666A - Method and device for boring of ink jet nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the forming of a through hole of a required configuration even when there is slight variability in the spatial distribution of laser energy by a method wherein the through hole is bored by projecting a laser beam from the inflow side of ink under the condition of masking and, subsequently, the laser beam is projected from the discharging side of the ink to spread the diameter of the hole. SOLUTION: A laser beam is projected from the inflow side of ink under the condition of masking through an optical member 3 to bore a convergent through hole. Subsequently, a work W is converted in front-and-rear direction and the laser beam is projected from the discharging side of ink under the condition of masking through the optical member 3 in the same manner to bore the through hole so as to obtain a final discharging side diameter by enlarging the diameter of the discharging hole to a diameter larger than the diameter of discharging side of the already bored through hole. Considering from the working characteristic of the laser beam, when viewed from the working direction of laser beam, the lengthwise directional configuration of the hole becomes a positive tapered shape and the taper angle of the hole is changed in accordance with the strength of laser energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming an ink jet nozzle in an ink jet printer.

[0002]

2. Description of the Related Art An ink jet nozzle employed in an ink jet printer is, for example, arranged in series with a strip-shaped workpiece (generally a resin material), and has through holes having a diameter of 31 μm and a depth of 50 μm at a constant pitch. , Formed in large numbers. In this case, the shape of each through-hole is circular in cross section, and in the longitudinal direction of the hole, the cross-sectional area on the ink inflow side is large, and the shape gradually decreases in the flow direction. ). For machining this hole,
Because of its size and the relationship of forming accuracy, it is difficult to employ mechanical means using a tool.
The method of decomposing and removing the resin material in the part corresponding to the hole,
It is commonly used.

[0003] Several methods have already been known for such a method of making a hole with a laser. That is, as one of the methods, there is a method of condensing the entire amount of the laser beam emitted from the oscillator with a lens, narrowing it down to a processing diameter, and processing the beam. There is a drawback that the removal shape becomes irregular and the through holes are not uniform. There is also a method of rotating and moving a laser beam narrowed down to a diameter smaller than a processing hole along a processing circumference of a through hole to be formed.
According to this, an accurate hole contour can be obtained, but there is a disadvantage that the mechanism for rotating and moving the beam becomes very complicated.

[0004]

Therefore, when an optical mask having a desired removal shape is used and transmitted therethrough,
A method has been proposed in which a cross-sectional shape of a laser beam is adjusted, and the laser beam is projected onto a processing surface of a workpiece using an imaging lens. In this method, since the processing size of the through-hole is determined by the accuracy of the mask dimension and the performance of the projection imaging lens, it is often used for the drilling of an inkjet nozzle requiring high precision.

FIG. 12 illustrates this mask projection system. Here, reference numeral 101 denotes a laser oscillator, 102 denotes an optical element (convex lens) for compressing the laser beam emitted from the oscillator 101 to increase the intensity, Reference numeral 103 denotes an optical member (optical mask) having a transmission window that regulates the cross-sectional shape of the laser beam to a required size and shape;
Reference numeral denotes an imaging lens for projecting a laser beam passing through the optical member 103 onto a processing surface of the workpiece W.

In order to open the through hole H in the workpiece W using the above-described drilling apparatus having an optical system, the resin in the portion of the projected image I is removed by a laser beam. In this case, the inner diameter of the through hole H is determined by the magnification of the imaging lens 104 and the diameter of the window (mask hole) of the optical member 103. The inner surface of the processed through hole H usually has a taper, though slightly, which tends to taper such that the deeper the hole is formed, the smaller the hole diameter becomes. The taper angle at this time varies depending on the energy intensity of the laser beam, and is usually about 5 to 7 °.

Considering the shape of the hole from the function of the ink jet, a positive tapered through hole having a large ink inflow port and a small discharge port increases the pressure with the flow of the ink. A stream is obtained, which is convenient for forming a desired droplet. Therefore, when drilling by the above-described mask projection method, when drilling holes with a laser from the ink discharge side of the workpiece, the cross-sectional area of the holes becomes an inversely tapered shape that gradually increases along the flow of ink, Negative pressure is generated in the direction of ink flow, causing turbulence in the flow, making it difficult to form a single lump of discharged droplets in good condition.

Therefore, in practice, a hole is drilled from the ink inflow side of the workpiece, but if there is a variation in the laser output or if the material thickness is uneven as shown in FIG. 13, the hole is formed based on the taper angle. There is a problem that the discharge port diameters (D ₁ to D _n ) vary according to the change in the length. However, in a so-called multi-nozzle long head in which a large number of through-holes (nozzle holes) are arranged, it is important to make the ejection port diameters uniform. Will be uneven.

The present invention has been made based on the above circumstances, and it is possible to form a through hole in a required shape by masking even if there is some unevenness in the spatial distribution of laser energy. An object of the present invention is to provide a method and an apparatus for forming an ink-jet hole, which have a uniform diameter on the ink ejection side and can obtain required droplets, even if the processing member has a thickness variation.

[0010]

Therefore, in the present invention,
In a method of forming an ink-jet nozzle that forms a positive tapered ink-jet nozzle hole whose diameter decreases from the ink inflow side to the ejection side using a laser, a laser beam is irradiated from the ink inflow side while masking Then, a tapered through-hole is drilled, and then, in a masked state, a laser beam is irradiated from the discharge side, and the diameter of the discharge hole is enlarged with a diameter larger than the diameter of the drilled through-hole on the discharge side. Then, a hole is formed so as to have a final diameter on the discharge side.

Further, according to the present invention, in a method for forming an ink jet nozzle having a positive tapered shape in which a diameter is reduced from an ink inflow side to an ejection side by using a laser, a masked state is formed. Irradiating a laser beam from the ink ejection side to form a slot having a final ejection side aperture, and then, in a masked state, irradiating a laser beam from the ink inflow side to obtain It is also possible to form a tapered through-hole with a large inflow-side diameter and to join the through-hole to the slot so as to intersect the peripheral surface of the slot immediately before the discharge port.

Further, according to the present invention, in a method for forming an ink jet nozzle having a positive tapered shape in which a diameter is reduced from an ink inflow side to an ejection side by using a laser, a masked state is formed. Alternatively, a laser beam may be irradiated from the ink discharge side to form a through hole having a final diameter on the discharge side with a reverse taper.

Further, according to the present invention, in a method of forming a positively tapered ink jet nozzle hole having a diameter decreasing from an ink inflow side to a discharge side by using a laser, a masked state is formed. A laser beam is irradiated from the ink discharge side to form a through hole having a final discharge side diameter, and further, a rotation common to each ink discharge port passing through the center of the laser optical axis on the discharge side surface of the workpiece. At the center, tilt the workpiece, and with the laser beam,
The ink jet nozzle may be perforated by increasing the cross-sectional area of the through hole toward the inflow side.

In this case, in the ink jet nozzle drilling apparatus of the present invention, an optical system used for laser drilling includes an optical element for compressing a laser into parallel light having a required intensity, and a masking mask for restricting transmitted light. And an optical element for slightly and omnidirectionally enlarging the laser transmitted through the optical member so as to have a reverse taper. Here, a means for tilting the workpiece at the center of rotation common to the ink ejection ports passing through the center of the laser optical axis on the ejection side surface of the workpiece may be provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be specifically described below with reference to the drawings. The configuration of the apparatus in the first, second and fourth embodiments (see FIG. 1) is the same as that employed in the above-described conventional mask projection system. That is, here, reference numeral 1 denotes a laser oscillator, 2 denotes an optical element (convex lens) that compresses the laser beam emitted from the oscillator 1 to increase the intensity, and 3 denotes a necessary laser beam by regulating the cross-sectional shape of the laser beam. An optical member (optical mask) 4 having a transmission window whose size and shape are formed is an imaging lens 4 for projecting the laser beam passing through the optical member 3 onto a processing surface of the workpiece W.

Further, the configuration of the device according to the third embodiment of the present invention (see FIG. 2) includes the following optical system. Here, reference numeral 11 denotes a laser oscillator, 12 denotes an optical element (convex cylindrical lens) that compresses the laser beam emitted from the oscillator 11 to increase the intensity, 1
5 is an optical element (collimator lens) that deflects the laser beam focused by the optical element 12 into parallel light, and 13 has a transmission window that regulates the cross-sectional shape of the laser beam and makes the laser beam have a required size and shape. For example, a metal optical member (optical mask) 14 diffuses the laser beam passing through the optical member 13 with a slight reverse taper, and projects an optical element (concave spherical surface) for projecting the laser beam on the processing surface of the workpiece W. Lens).

The configuration of the optical system of the above-described apparatus shows only the basic part, and actually includes additional components such as adding an optical homogenizer lens for making the beam energy distribution uniform. Although each optical element is shown by a single lens, it is needless to say that a composite lens system may be used to reduce optical aberrations. (First Embodiment) Next, a drilling method according to a first embodiment of the present invention will be specifically described with reference to FIGS. Here, the drilling process is divided into two, and the nozzle hole is drilled from both the ink inflow side and the ejection side. That is, as shown in FIG.
In in a state in which the masking, by irradiating a laser beam from the ink inlet side, (see Figure 3) drilling a through-hole H ₁ of the tapered, then reversed back and forth workpiece W (see FIG. 4 ) Similarly, with the optical member 3 masked,
The laser beam irradiated from the discharge side, a large diameter d ₂ than the ejection-side diameter d ₁ of the drilled through-hole H _1, by expanding the diameter of the discharge hole, so that the final discharge side diameter d ,
Drill.

That is, considering the processing characteristics by laser,
When viewed from the processing direction, the shape of the hole in the longitudinal direction becomes a positive taper shape, and the hole taper angle changes according to the intensity of the laser energy (see FIG. 6: here, the laser output and the hole taper angle). And the relationship of the hole opening diameter on the machining side is shown). Further, since the contour of the processing hole on the projection surface of the workpiece W on which the laser is projected is determined by masking the optical member 3, the required shape is properly maintained, and the small.

For this reason, the present invention utilizes the fact that if a hole is formed from the discharge side, the diameter of the discharge side hardly changes. That is, for example, as a reference surface F the surface of the ink inlet side of the workpiece W, as shown in FIG. 3, drill narrows positive taper-shaped through hole H ₁ from the inlet side to the discharge side. At this time, if the energy intensity of the laser fluctuates, the taper angle changes, and the discharge port diameter d _{1 of the} primary processing changes. The diameter of the window of the optical member (mask) 3 is adjusted so that the expected maximum dimension is slightly smaller than the final ejection side diameter d.

Next, as shown in FIG. 4, the workpiece W is turned 180 degrees back and forth and replaced with an optical member (mask) 3 corresponding to the final ejection side diameter d. Is set as a reference plane F ′, a laser is emitted from the discharge side of the workpiece W,
Irradiation is performed again, and the discharge side diameter is enlarged. In this case, even if there is variation in the thickness of the workpiece W, the final discharge side diameter d
It is effective to reduce the amount of removal from the discharge side in the second processing to make the joint point of both processings closer to the discharge side in order to minimize the variation of the processing. Therefore, the discharge side diameter d ₁ (<d) formed in the primary processing
As close as possible to the final discharge side diameter d. In order to reduce the taper angle during the secondary processing as much as possible, it is preferable to increase the laser energy intensity at this time.

If the reference plane F for the primary processing is adopted as the reference plane for the secondary processing, the laser beam projected onto the discharge-side surface with a variation in the thickness of the workpiece W is varied. Although the diameter of the projected image of the beam varies, the position of the joint point of both processes is a fixed distance from the reference plane F, so that the final discharge side diameter d is constant without being affected by the difference in the plate pressure. (See FIG. 5). (Second Embodiment) Next, the second embodiment of the drilling method of the present invention will be described.
The embodiment will be specifically described with reference to FIGS. 7 and 8. FIG. Here, the processing order is reversed, first, with respect to the workpiece W, to form a circular cross section slot (non-through hole) H ₂ from the ink discharge side, then, slot H from the ink inlet side
Connect to _2, it is to drill a through hole H _3.

[0022] That is, as shown in FIG. 1, in a state where the masking an optical member 3, a laser beam is irradiated from the ink discharge side, the final discharge side diameter slot of H ₂ d was formed (FIG. 7 see), then again, in a state where the masking in the optical member of the window holes of diameter to accommodate, by irradiating a laser beam from the ink inlet side, the slots of H ₂ diameter d greater inflow side diameter than d ₃ , a tapered through hole H ₃ is opened, and the through hole H ₃ is intersected with the peripheral surface of the slot H ₂ immediately before the discharge port.
₃ is attached to slots H ₂ (see Figure 8).

[0023] In this case, just like in consideration in the first embodiment, the diameter of the slots H ₂ to drill in primary processing, placed in the final discharge side diameter d, the groove depth is possible shallower And put. The depth of the groove is set by the number of pulsed laser beams, and is 0.05 to 0.2 μm per shot.
Therefore, the hole contour can be formed with higher accuracy than the entire depth when the through hole is formed. Further, in order to reduce the taper angle at that time, it is preferable to increase the laser energy intensity. The first fabrication of slots H ₂ and the secondary processing of the through hole H
₃ binds position, the peripheral surface of the slot H ₂ is desirable. Incidentally, if it binds with the bottom surface of the slot H _2, with respect to the flow of ink, form the cross-sectional area of the holes increases discontinuously (see Figure 9)
Therefore, a sudden change in the ink fluid pressure is caused, and there is an adverse effect such as a division of the liquid and a change in the ejection direction. (Third Embodiment) Using the drilling device shown in FIG.
A third embodiment of the drilling method according to the present invention will be specifically described. Here, in a state where the masking by optical element (mask) 13 is to form the ink discharge side of the laser beam irradiated from the final discharge side diameter d through hole H ₄ of the workpiece W (FIG. 10). The adjustment of the taper angle is performed based on the power of each concave lens, that is, the lens curvature, and the lens curvature is selected according to the desired taper angle of the hole. As a result, the laser light at the processing location has a spread, and the aperture of the processing surface is set by the distance from the final lens.

In this case, if the final spread angle of the laser beam is, for example, 6 °, tan6 ° =
0.105, and the variation of the final discharge side diameter d is 1 μm.
In order to reduce the distance between the optical system and the surface to be processed, an error of 10 m or less may be taken into consideration. The taper angle of the nozzle hole can be set to a considerably small value in the case of a normal ink jet, because a sufficient pressure rise effect of the ink liquid can be set at several degrees. It does not become. (Fourth Embodiment) A fourth embodiment of the drilling method of the present invention will be specifically described using the drilling device shown in FIG. In this case, two or more types of positive tapered through holes having different azimuth angles are formed from the discharge side of the workpiece W. That is, here, the optical member (mask)
In the state where the masking is performed in Step 3, the laser beam is irradiated from the ink discharge side of the workpiece W into, for example, a positive taper (taper).
Irradiating the together form a through hole H ₅ final discharge side diameter d, further, in common rotation center to each of the ink discharge ports through the laser beam axis center C of the discharge side of the workpiece W , by tilting the workpiece W, or the laser beam, by enlarging the sectional area of the through hole H ₅ toward the inflow side, is to carry out the drilling of the jet nozzle (see Figure 11).

In this case, the workpiece W may be reciprocated a plurality of times within a predetermined inclination angle while continuously irradiating the laser beam. As a result, in the obtained hole shape, the cross section in the direction perpendicular to the inclination in the depth direction has a slightly reduced diameter determined by the processing characteristics of the laser beam, but the hole shape on the ink inflow side has an inclination. It is a long hole long in the direction, gradually toward the discharge side,
It has a taper that shrinks and has the smallest elliptical cross section on the discharge side. In other words, the ink has a positive taper shape in which the cross-sectional area of the hole decreases in the direction of flow, so that the action on the ink flow is in the direction of increasing the ink fluid pressure, and normal ink droplets are obtained.

[0026]

【Example】

(Example 1) A specific example of the first embodiment of the present invention is shown below. Here, 50 nozzle holes are formed in series at a pitch of 70 μm with respect to a polysulfone resin plate-like workpiece having a thickness of 50 μm, with an ejection hole diameter of 31 μm.
In this case, a KrF excimer laser (INN of Lumonix) was used.
(DEX200). In the first processing, the condensed laser energy was 250 mJ / pulse, the processing was performed at a repetition frequency of 200 Hz, and the oscillation time was 2 seconds, and a through hole was formed from the ink inflow side. In the second processing, the material to be processed is turned back and forth by 180 degrees, and the laser energy is 400 mJ / pulse from the ink discharge side.
Processing was performed at a repetition frequency of 200 Hz and an oscillation time of 0.1 second.

In the first processing, the opened inlet diameter is 31 μm.
m, and the discharge port diameter was 25 to 27 μm. Work material 1
In the second processing, the optical mask was exchanged, and the resin was removed in a range from the discharge port to a position having a depth of 5 μm in the second processing. As a result, the final discharge side diameter becomes 28
２９29 μm, and the variation is reduced as compared with the prior art. (Example 2) A specific example of the second embodiment of the present invention will be described below. Here, the same optical system, laser, and workpiece as in the secondary processing of the first embodiment, laser energy from the outflow side: 400 mJ / pulse, repetition frequency:
Processing at 200 Hz, oscillation time: 0.2 seconds, discharge diameter: 2
A circular slot having a thickness of 8 to 29 μm and a depth of 5 μm was formed. Next, the workpiece is turned over, a through hole is formed under the same processing conditions as the primary processing of the first embodiment, and connection with the primary processing groove is performed at the peripheral surface of the groove. Is done so that
There was almost no change in the diameter of the final discharge side. (Example 3) A specific example of the third embodiment of the present invention will be described below. Here, 50 nozzle nozzle holes are formed in series at a pitch of 70 μm with respect to a plate-like workpiece of polysulfone resin having a thickness of 50 μm, with a discharge hole diameter of 31 μm.
In this case, a KrF excimer laser (INN of Lumonix) was used.
(DEX200). In addition, in forming 50 nozzles in series at a pitch of 70 μm, a hole diameter of 31 μm, and a plate member thickness of 50 μm with an inkjet nozzle hole, the laser beam after passing through the mask is obtained by the first means using Lumonix INDEX200 as an excimer laser. The beam is expanded by a beam expanding lens, and is radiated on the surface to be processed as a slightly spread beam.

The laser energy condensed so as to transmit through the mask is 250 mJ / pulse, the beam divergence angle at the last stage is 7 degrees, the repetition frequency is 200 Hz, and the oscillation time is 2 Processed in seconds. At this time, unlike the case of the conventional mask reduction projection optical system, the shape of the hole becomes a wide taper shape (a so-called reverse taper) first, and the diameter of the 50 nozzle holes, that is, the creation of the ink ejection side diameter. The error is considerably smaller than the conventional one, 31 ±
It was about 0.5 μm. (Example 4) Next, a specific example of the fourth embodiment of the present invention will be described below. Here, a conventional mask projection method is adopted, and a laser beam is projected onto a processing surface (ink ejection side) so that an optical mask image is projected on a processing surface (ink ejection side) in a state reduced by an optical system. Irradiated. The laser application condition in this case is as follows: laser energy: 125
mJ / pulse, repetition frequency: 100 Hz, oscillation time: 2 seconds, thereby drilling a hole. Next, the workpiece is tilted 6 degrees with respect to the center of the discharge side hole,
A hole was drilled under the same conditions as described above. As a result, the processed hole had an elliptical shape (area: 759.3 μm ² ) with a discharge port diameter: 31 × 31.2 μm, and an inlet diameter: 29 × 3.
A desired nozzle hole having an irregular shape of 2.2 μm (area: 805 μm ² ) and having a larger cross-sectional area on the inflow side than on the discharge side was obtained. (Example 5) Another specific example of the fourth embodiment of the present invention is shown below. Also in this case, the same mask projection system as that of the fourth embodiment is employed.
The laser beam is irradiated while being swung at 3 degrees.
Laser application conditions were: laser energy: 125 mJ / pulse, repetition frequency: 100 Hz, oscillation time: 4 seconds, and the reciprocating swing was repeated twice. As a result, the processed hole had an elliptical shape (area: 759.3 μm ² ) with a discharge port diameter: 31 × 31.2 μm, and an inlet diameter: 29.
A desired nozzle hole having a size of × 32.2 μm (area: 810 μm ² ) and a larger cross-sectional area on the inflow side than on the discharge side was obtained.

[0029]

The present invention has been described above. By using means for determining the diameter of a discharge hole by processing from the discharge side, even if the energy distribution of the laser beam is uneven,
In addition, even if there is an error in the thickness of the plate-shaped workpiece constituting the nozzle, the variation in the diameter of a large number of ink jet ejection holes can be made as small as possible, and the ink ejection amount can be made uniform. be able to. This makes it possible to realize a long multi-nozzle with little production unevenness.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a drilling device when implementing first, second, and fourth embodiments of the present invention.

FIG. 2 is a schematic configuration diagram of a drilling device when implementing a third embodiment of the present invention.

FIG. 3 is a cross-sectional view of a workpiece in a first working for explaining the first embodiment of the present invention.

FIG. 4 is also a cross-sectional view of a workpiece in a second processing for explaining the first embodiment.

FIG. 5 is a sectional view of a workpiece similarly showing another aspect in the secondary processing.

FIG. 6 is a graph showing a relationship between a taper angle for forming a nozzle hole and a diameter in the present invention.

FIG. 7 is a cross-sectional view of a workpiece in a first working for explaining a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a workpiece in a second processing for explaining the second embodiment.

FIG. 9 is a partial cross-sectional view of a workpiece, indicating a problem that needs to be considered when implementing the present invention.

FIG. 10 is a cross-sectional view of a workpiece for explaining a third embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a drilling device when implementing a fourth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a conventional drilling device.

FIG. 13 is a cross-sectional view showing a difference in the diameter of the discharge side of the nozzle hole due to a difference in the thickness of the workpiece due to the conventional drilling.

[Explanation of symbols]

1, 11 Laser oscillator 2, 12 Optical element (convex lens, convex cylindrical lens) 3, 13 Optical member (optical mask) 4 Imaging lens 14 Optical element (concave spherical lens) 5 Optical element (collimator lens) W Workpiece H ₁ , H ₃ , H ₄ , H ₅ Through hole H ₂ slot hole d Final discharge side diameter d ₁ Discharge side diameter d ₂ Port diameter d ₃ Inflow side diameter

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroharu Narumi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (6)

[Claims] 1. A method for forming an ink jet nozzle having a positive tapered shape in which a diameter is reduced from an ink inflow side to an ejection side by using a laser. Irradiates a laser beam from, drilling a tapered through-hole, then, in a masked state, irradiate the laser beam from the discharge side, with a diameter larger than the discharge-side hole diameter of the drilled through-hole, A method for drilling an ink jet nozzle, characterized in that the diameter of the discharge hole is enlarged and the hole is drilled so as to have a final diameter on the discharge side. 2. A method for forming a positively tapered ink jet nozzle hole having a diameter decreasing from an ink inflow side to a discharge side by using a laser. To form a slot with a final ejection side aperture, and then, in a masked state, irradiate a laser beam from the ink inflow side to make the inflow side aperture larger than the aperture of the slot. Wherein the through hole is joined to the slot so as to intersect the peripheral surface of the slot immediately before the discharge port. 3. A method for forming an ink jet nozzle having a positive tapered shape in which a diameter is reduced from an ink inflow side to an ink discharge side by using a laser. Characterized in that a laser beam is emitted from the substrate to form a through hole having a final discharge side diameter with an inverse taper. 4. A method for forming an ink jet nozzle having a positive tapered shape in which a diameter is reduced from an ink inflow side to an ink discharge side by using a laser. A laser beam is irradiated from the surface of the workpiece to form a through hole having a final diameter on the discharge side, and a rotation center common to each ink discharge port passing through the center of the laser optical axis on the discharge side surface of the workpiece. A method for drilling an ink jet nozzle, characterized in that a workpiece is tilted so that a cross-sectional area of a through hole is increased toward an inflow side by the laser beam. 5. An ink jet nozzle punching device for forming a positive tapered ink jet nozzle hole whose diameter is reduced from an ink inflow side toward an ejection side by using a laser, wherein an optical system used for laser drilling includes: An optical element for compressing the laser into parallel light of a required intensity, an optical member for masking that restricts transmitted light, and a slightly omnidirectionally uniform laser so that the laser transmitted through the optical member has a reverse taper. An ink jet nozzle drilling device, comprising: an optical element for enlargement. 6. The apparatus according to claim 5, further comprising means for inclining the workpiece at a center of rotation common to each ink ejection port passing through the center of the laser optical axis on the ejection side surface of the workpiece. Drilling device for inkjet nozzles.