JP2001187451A - Printing head, production method therefor, orifice plate used in the head, and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the printing resolution without causing deterioration of the printing quality. SOLUTION: This device comprises an orifice plate 6 having a plurality of orifices 7, and a head body 5 provided integrally with the orifice plate, sectioned into a plurality of ink chambers 12 for guiding an ink to each of the orifices, for ejecting the ink from the corresponding orifice by increasing the pressure of each ink chamber, wherein each orifice has a necking for limiting the ink ejecting direction error substantially to ±5 mrad or less with respect to the orifice central axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head for printing a dot image with ink droplets ejected from a plurality of ink ejection holes, a method for manufacturing the same, an orifice plate used for the head, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A print head of a typical ink jet printer has a head body and an orifice plate fixed to an end of the head body. The orifice plate has a plurality of orifices arranged as ink ejection holes. An ink ejection mechanism such as a bubble jet (registered trademark) type or a Kaiser type ejects ink from a plurality of ink chambers defined by partition walls and pressures of the respective ink chambers and corresponding orifices. Having. The bubble jet ink ejection mechanism increases the pressure in the ink chamber due to the generation of bubbles during ink ejection, and the Kaiser ink ejection mechanism increases the pressure in the ink chamber due to deformation of the partition walls during ink ejection.

The orifice plate is formed with a plurality of orifices by a plating method generally called electroforming so that the orifice plate has a forward tapered shape having a gradually decreasing diameter from the ink inflow side toward the ink discharge side. It consists of a fixed metal plate. However, it is difficult for this plate structure to further narrow the orifice pitch in order to print a dot image with high resolution. That is, the adhesive flows from the main surface of the plate into the adjacent orifice in the step of bonding the orifice plate, and is likely to cause clogging which hinders ink flying.

When the orifice pitch is close to the limit for such a reason, for example, a drive system in which the print head is repeatedly driven while shifting the print head at a pitch smaller than the orifice pitch in the arrangement direction of the orifices is used. Higher resolution is achieved. However, this driving method has a problem that it is difficult to obtain a clear dot image because the dot print position varies depending on the precision of the shift mechanism of the print head.

[0005] Japanese Patent Application Laid-Open No. Hei 5-330064 discloses a technique capable of solving the above-mentioned problem. In this publication, an orifice plate is formed of a resin plate previously fixed to an end of a head body, and a plurality of orifices are formed by irradiating a laser beam to the resin plate from an ink discharge side. The laser light is condensed by the imaging optical system so as to have the smallest beam diameter at the focal point set in the space on the ink ejection side, and enters the resin plate while spreading from this focal point. In this resin plate, ablation proceeds at a portion exposed to the laser beam, thereby forming a forward tapered orifice having a gradually decreasing diameter from the ink inflow side toward the ink discharge side. In this case, the adhesive that causes clogging does not flow into the orifice,
The orifice pitch can be set sufficiently small to print a dot image with high resolution.

However, if the relative positional relationship between the focal point of the imaging optical system and the resin plate cannot be kept constant for each orifice, the minimum diameter of these orifices will vary due to the spread of the laser light, and uniformity will occur. It becomes difficult to print dots of a size.

Japanese Patent Application Laid-Open No. 10-76666 discloses an orifice forming technique capable of reducing the variation in the minimum diameter of the orifice. In this publication, a plurality of orifices are formed by irradiating a resin plate with laser light from an ink inflow side and an ink discharge side. The laser light from the ink inflow side is condensed by the imaging optical system so as to have the smallest beam diameter at the focal point set in the space on the ink ejection side, and enters the resin plate on the way to this focal point. At this time, the ablation proceeds at the portion of the resin plate exposed to the laser beam, thereby forming a forward tapered orifice having a gradually decreasing diameter from the ink inflow side toward the ink discharge side.

Further, the laser light from the ink discharge side is condensed by the imaging optical system so as to have the smallest beam diameter at the focal point set in the space on the ink inflow side, and is directed to the resin plate on the way to this focal point. Incident. At this time, the ablation proceeds at the portion of the resin plate exposed to the laser beam, thereby causing the orifice to have an inverted taper near the surface of the resin plate on the ink ejection side. This can compensate for variations in the diameter of the orifice generated on the ink ejection side.

However, this orifice forming technique requires laser light to be applied to the resin plate from the ink inflow side in order to form each orifice. It is difficult to fix to the end of the body. If the resin plate is fixed to the head body with an adhesive after the formation of the orifice, the adhesive may flow from the main surface of the plate into the adjacent orifice and cause clogging of the orifice. Therefore, the orifice pitch cannot be set sufficiently small to print a dot image with high resolution.
In addition, since the laser beam is applied to the resin plate not only from the ink inflow side but also from the ink ejection side, a step is likely to occur at the boundary between the forward tapered portion and the reverse tapered portion at each orifice due to the displacement of the laser light. The step disturbs the flow of the ink ejected from the orifice due to the change in the pressure of the ink chamber, resulting in a variation in the ejection direction of the ink droplet.

[0010]

As described above, the structure disclosed in Japanese Patent Laid-Open Publication No. Hei 5-330064 has a problem that the minimum diameter of the orifice varies and it becomes difficult to print dots of uniform size. Further, in Japanese Unexamined Patent Application Publication No. 10-76666, there is a problem that the orifice pitch cannot be set to be sufficiently small, and that the ejection direction of ink droplets varies.

Accordingly, the inventions according to claims 1 to 5 provide a print head capable of improving print resolution without deteriorating print quality.

Further, the invention according to claims 6 to 13 provides a method of manufacturing a print head which can improve print resolution without deteriorating print quality.

Further, the invention according to claim 14 provides an orifice plate used for a print head capable of improving print resolution without deteriorating print quality.

[0015] The invention according to claim 15 provides a method of manufacturing an orifice plate used in a print head capable of improving print resolution without deteriorating print quality.

[0015]

According to the first aspect of the present invention,
An orifice plate having a plurality of orifices arranged as ink ejection holes and a plurality of ink chambers for guiding ink to the plurality of orifices, respectively, and integrated with the orifice plate to increase the pressure of each ink chamber. And a head body for ejecting ink from the orifice, and each orifice is a print head having a constriction that limits an ink ejection direction error with respect to a center axis of the orifice to substantially ± 5 mrad or less.

According to a second aspect of the present invention, in the print head according to the first aspect, the constriction is gradually reduced to a predetermined opening size from the ink inflow side to the ink discharge side in the thickness direction of the orifice plate. And a non-forward tapered portion connected to the forward tapered portion.

According to a third aspect of the present invention, in the print head according to the second aspect, the non-forward tapered portion has an opening substantially the same as a predetermined opening size from the ink inflow side to the ink discharge side in the thickness direction of the orifice plate. The straight part is the size.

According to a fourth aspect of the present invention, in the print head according to the second aspect, the non-forward tapered portion gradually widens from a predetermined opening size from the ink inflow side to the ink discharge side in the thickness direction of the orifice plate. The reverse tapered portion is formed as follows.

According to a fifth aspect of the present invention, in the print head according to the second aspect, the depth of the non-forward tapered portion is within 30% of the thickness of the orifice plate.

According to a sixth aspect of the present invention, in the print head of the second aspect, the orifice plate includes a water-repellent layer formed as an ink ejection side surface and surrounding the non-forward tapered portion.

According to a seventh aspect of the present invention, there is provided an adhesive step of bonding an orifice plate to a head body divided into a plurality of ink chambers by an adhesive, and a step of arranging ink discharge holes communicating with the plurality of ink chambers. Forming an orifice plate on the orifice plate by irradiating a laser beam with a plurality of orifices for ejecting ink by increasing the pressure of the laser beam.The opening step includes an imaging optical system having a light-collecting surface set inside the orifice plate. A forward taper portion that converges the laser beam and gradually narrows to a predetermined opening size from the ink inflow side toward the ink ejection side in the thickness direction of the orifice plate, and a non-forward taper connected to the forward taper portion Prints that include a shaping step to constrict the orifice by simultaneously forming the In the manufacturing method of de.

According to an eighth aspect of the present invention, in the method of manufacturing a print head according to the seventh aspect, the opening step is performed after the bonding step.

According to a ninth aspect of the present invention, in the method of manufacturing a print head according to the seventh aspect, the laser beam is irradiated on the ink ejection side surface of the orifice plate.

According to a tenth aspect of the present invention, in the method for manufacturing a print head according to the seventh aspect, the orifice plate has a water-repellent film as an ink ejection side surface, and the shaping step includes bonding a protective film to the water-repellent film. And a step of irradiating a laser beam in a state in which the protection film is removed after the irradiation.

According to an eleventh aspect of the present invention, in the method for manufacturing a print head according to the seventh aspect, the depth of the non-forward tapered portion is determined by the position of the condensing surface set by the imaging optical system and the thickness of the orifice plate. In the direction of movement.

According to a twelfth aspect of the present invention, in the method for manufacturing a print head according to the seventh aspect, the non-forward tapered portion comprises:
In the thickness direction of the orifice plate, the straight portion has the same opening size as the predetermined opening size from the ink inflow side to the ink discharge side.

According to a thirteenth aspect of the present invention, in the method for manufacturing a print head according to the seventh aspect, the non-forward tapered portion includes:
An inverse tapered portion that gradually widens from a predetermined opening size from the ink inflow side to the ink discharge side in the thickness direction of the orifice plate is provided.

According to a fourteenth aspect of the present invention, there is provided a laminate of a resin plate and a liquid-repellent film covering the resin plate, and a plurality of orifices arranged as ink discharge holes in the laminate. A forward tapered portion which gradually narrows to a predetermined opening size from the ink inflow side to the ink ejection side in the thickness direction, and a non-forward taper having a depth within 30% of the thickness of the laminate connected to the forward tapered portion The orifice plate has a constriction constituted by a section.

According to a fifteenth aspect of the present invention, a laminating step of forming a laminated body of a resin plate and a liquid-repellent film and an opening step of forming a plurality of orifices arranged as ink discharge holes in the laminated body by irradiating a laser beam. The opening step includes condensing laser light using an imaging optical system having a condensing surface set inside the multilayer body, and performing a predetermined operation from the ink inflow side to the ink ejection side in the thickness direction of the multilayer body. Shaping to constrict the orifice by simultaneously forming a forward taper portion gradually narrowing to the opening size and a non-forward taper portion connected to the forward taper portion and having a depth within 30% of the thickness of the laminated body. A method for manufacturing an orifice plate including steps.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the appearance of an ink jet print unit 1. The ink jet print unit 1 includes a base plate 2 used as a support member, a print head 3 for printing a dot image with ink droplets, and a drive circuit board for driving the print head 3. 4 is provided.

The print head 3 and the drive circuit board 4 are mounted on the base plate 2. The print head 3 includes a head body 5 and an orifice plate 6 integrated with the head body 5. The orifice plate 6 has a plurality of orifices 7 arranged as ink ejection holes at a predetermined pitch of 80 μm or less. The head body 5 is connected to an ink tube 8 for supplying or discharging ink.

FIG. 2 is a view showing a cross-sectional structure of the print head 3 along the row of the orifices 7.
Changes the pressures of the plurality of ink chambers 12 formed as elongated grooves for guiding the ink to the orifices 7 and the ink chambers 12 to eject ink from the corresponding orifices 7 in the ink ejection direction indicated by arrows in FIG. , For example, a Kaiser-type ink ejection mechanism AC.

This ink discharge mechanism AC is composed of an electrostrictive member, and has a plurality of partitions 11 for partitioning the head body 5 into a plurality of ink chambers 12, and a plurality of electrodes 10 added so as to sandwich these partitions. By applying a voltage to these electrodes 10 at the time of ink ejection, these partition walls 11 are deformed to increase the pressure in the ink chamber 12. The drive circuit board 4 is composed of a plurality of IC chips or the like for driving the ink ejection mechanism AC of the print head 3, and is connected to an external controller by a connection cable 9.

The orifice plate 6 includes a resin plate 14
And a liquid-repellent film 13 that covers the resin plate 14 on the ink ejection side to repel ink. The liquid repellent film 13 is made of a polymer resin such as a polymer material such as polyimide, which has a high absorption coefficient for light having a wavelength in the ultraviolet region.

Each of the orifices 7 has a diameter of 30 μm or less and penetrates through the laminated body. Each of the orifices 7 communicates with the ink chamber 12 by fixing the orifice plate 6 to an end of the head body 5. . Each of the orifices 7 has a constriction formed such that a reverse taper portion is disposed on the ink discharge side and a forward taper portion is disposed on the ink inflow side. The reverse tapered portion is provided to increase the straightness of the ejected ink by increasing the pressure of the ink chamber 12 and improve the ejection efficiency of the ink.

FIG. 3 is a view showing a configuration of a hole processing device used for manufacturing the print head shown in FIG. 2. The orifice 7 of the orifice plate 6 is formed by the hole processing device. This hole processing apparatus includes a KrF excimer laser oscillator 30, a variable attenuator 31, an up collimator 32, an image rotator 33, a mirror 34, an array lens illumination system 35, a relay lens 39, a first mask 36A, a second mask 36B, and a projection. It has a lens (imaging lens) 37, an X stage 38a, a Y stage 38b, and a Z stage 38c.

Reference numeral 48 denotes a fine processing controller, which has a function of transmitting a laser control signal (trigger signal) to the excimer laser oscillator 30 and controlling the operation of the excimer laser oscillator 30. . Further, the micromachining controller 48 sends a rotation speed control signal to the image rotator 33, and continuously rotates the image rotator 33 during irradiation of, for example, 200 pulses of laser light necessary for drilling the orifice plate 20. And has the function of rotating.

The micro-machining controller 48 sends a fluence control signal to the variable attenuator 31 to adjust the output intensity of the laser light according to the number of laser light pulses output from the excimer laser oscillator 30. have. Further, the fine processing controller 4
8 sends a focus control signal to the auto-focus unit 49 to convert the mask image into the orifice plate 2.
It has a function of forming an image at 0.

This auto focus unit 49 includes:
A camera 50 is connected, and has a function of calculating a focus shift based on a mask image on the orifice plate 20 captured by the camera 50 and transmitting a drive signal for eliminating the focus shift to the z driver 61. .
This z driver 61 is
Has a function of operating the z stage 38c in accordance with the drive signal from

The micromachining controller 48 has a function of transmitting a position control signal to the xy driver 62 and operating the xy tables 38a and 38b so that the mask image is projected on the orifice plate 20. .

The KrF excimer laser oscillator 30 comprises:
A pulsed laser beam is output in an ultraviolet region having a wavelength of 400 nm or less. The variable attenuator 31, the up collimator 32, the image rotator 33, and the mirror 34
It is arranged on the optical path of the laser light output from the KrF excimer laser oscillator 30. Array lens illumination system 35, relay lens 39, mask 36A, mask 3
6B and the projection lens 37 are arranged on the reflection optical path of the mirror.

The X stage 38a and the Y stage 38
b and the Z stage 38c are provided in the optical axis direction of the projection lens 37, and respectively move the orifice plate 6 of the print head 3 mounted as a workpiece on the Z stage 38c to the X axis, the Y axis, and the It is configured to be movable in the Z-axis direction.

Here, a specific configuration of the optical system of the array lens illumination system 35, the relay lens 39, the masks 36A and 36B, and the projection lens 37 will be described with reference to FIG. As shown in FIG. 4, an array lens illumination system 35, a relay lens 39, a first mask 36A, a second mask 36B, and a projection lens 37 are arranged on the optical path of the laser light.

As shown in FIGS. 4 and 5, the array lens illumination system 35 includes two cylindrical lenses 35.
a and 35b are arranged at an interval L0 in a direction perpendicular to each other. Each of the light condensing surfaces 42 (surfaces including the light condensing points) of these cylindrical lenses 35a and 35b coincides with the same surface at a distance L1 from the cylindrical lens 35b.

Further, these cylindrical lenses 35
The condensing surfaces 42a and 35b are imaged by the relay lens 39 on the surface of the entrance pupil (aperture) 41 of the projection lens 37, whereby the array lens illumination is performed on the projection lens 37 so that the telecentric condition is satisfied. A first mask 36A and a second mask 36B are arranged for the system 35, the relay lens 39, the entrance pupil 41, and the projection lens 37.

By irradiating a laser beam from the ink ejection side through such a telecentric optical system,
Orifice 7 having an axis perpendicular to the plate surface of orifice plate 6 and having a reverse tapered portion and a forward tapered portion.
Is formed.

Next, a specific method for forming the orifice 7 on the orifice plate 6 by the hole processing device will be described. FIG. 6 shows the structure of the orifice plate 6 (plate to be processed) before the orifice 7 is formed by the hole drilling device. Here, the orifice plate 6 is the resin plate 1
4 and a liquid repellent film 13,
Is covered by a liquid repellent film 13.
A protective film 51 for protecting the liquid-repellent film 13 is temporarily fixed to the surface of the liquid-repellent film 13 with an adhesive 52.

Next, as shown in FIG. 7A, a laser beam shaped by using the above-described hole processing apparatus is irradiated from the ink discharge side of the orifice plate 6 as shown in FIG. When this laser beam passes through the telecentric optical system of the above-described hole drilling device, a cross section perpendicular to the traveling direction of the laser beam forms a condensing surface 40.
The beam is shaped so that the diameter gradually becomes narrower and the vertical cross section from the condensing surface 40 becomes a narrow beam shape so that the diameter gradually increases.

In this embodiment, the laser beam condensing surface 40 having such a constricted beam shape is processed while being positioned inside the cross section of the orifice plate, so that the reverse tapered portion 7a and the forward tapered portion 7b are separated from each other. The orifice 7 is formed on the orifice plate 6. here,
The orifice plate 6 protected by the protective film 51 is irradiated with laser light from the ink discharge side to form the orifice 7, and then the protective film 51 is peeled off to complete the orifice plate 6. The orifice thus formed is shown in FIG. The processing is promoted by absorbing the laser beam by the effect of the protective film 51, and the disturbance of the edge shape at the ink discharge port is suppressed.

Here, the entire process of forming such an orifice 7 will be described more specifically. First, (a) of FIG.
As shown in FIG. 7, an adhesive 52 is applied on the liquid-repellent film 13 formed on the surface of the orifice plate 6 to repel ink, and a protective film 51 is attached. Next, FIG.
As shown in (b), the hole processing apparatus is controlled to irradiate a laser beam having a narrow beam shape from the ink ejection side protected by the protection film 51 toward the orifice plate 6.

Subsequently, as shown in FIG. 8C, after the holes are penetrated by the irradiation of the laser beam, the orifice plate 6
Then, the protective film 51 is peeled off together with the adhesive 52. Thus, an orifice 7 having a constriction is formed on the orifice plate 6 as shown in FIG.

In these series of processes, the orifice 7 is formed while the orifice plate 6 is fixed to the head body 5 in advance. Therefore, clogging of the orifice 7 caused by the inflow of the adhesive or the like can be prevented. The orifice 7 having various constrictions can be formed by changing the beam shape of the laser beam under the control of the hole processing apparatus.

For example, by irradiating the orifice plate 6 with a small stop angle θ of the laser beam as shown in FIG. 9A, the vicinity of the condensing surface 40 as shown in FIG. The orifice 7 having the straight portion 7c having almost no taper can be formed.

Also, by controlling the hole processing device, the laser light focusing surface 4 inside the cross section of the orifice plate 6 is controlled.
By moving the zero position closer or farther in the thickness direction of the orifice plate 6, the depth W of the reverse tapered portion 7a defined by the constriction of the laser beam can be changed.

For example, as shown in FIG. 10, when the condensing surface 40 of the laser beam is positioned so as to be deviated toward the ink ejection side in the thickness direction of the orifice plate 6, the depth W of the reverse tapered portion 7a of the orifice 7 becomes shorter. can do. Further, as shown in FIG. 11, when the laser light focusing surface 40 is positioned so as to be biased toward the ink inflow side in the thickness direction of the orifice plate 6, the depth W of the reverse tapered portion 7a of the orifice 7 is reversed. Can be lengthened.

Since the forward tapered portion 7b of the orifice 7 has the effect of increasing the pressure of the ink, the ink can be ejected with a small ejection force when the depth W of the forward tapered portion 7b is long. . For this reason, if the depth W of the reverse taper portion 7a of the orifice 7 is longer than the depth of the forward taper portion 7b, the ink ejection pressure drops significantly when ink is ejected from the reverse taper portion 7a, and the ink ejection speed decreases. It causes inconveniences such as inviting. Also, the reverse tapered portion 7a
Is too long, the straightness in the ink ejection direction is impaired.

Therefore, it is desirable that the depth W of the reverse tapered portion 7a of the orifice 7 is less than half of the entire length of the orifice 7. The straight portion 7c shown in FIG.
The same is true for the orifice 7 having. As described above, by adjusting the position of the laser light focusing surface 40 inside the cross section of the orifice plate 6, the orifice 7 in which the depth of the forward tapered portion 7b is appropriately restricted can be formed.

As described above, in this embodiment, the reverse tapered portion 7a and the forward tapered portion 7b of the orifice 7 are simultaneously formed by a single process of irradiating the laser beam so as to be constricted inside the orifice plate 6. be able to.

Here, the difference in the ink ejection characteristics depending on the orifice shape will be described. FIG. 12A shows an orifice 7 having only a forward tapered portion 7b for discharging ink in an ink discharging direction indicated by an arrow. This forward tapered portion 7
b is formed to have a taper angle of 12 ° and a depth of 30 μm in the orifice plate 6 having a thickness of 30 μm.

FIG. 12B shows an orifice having a reverse tapered portion 7a and a forward tapered portion 7b for discharging ink in the ink discharging direction indicated by the arrow. The reverse taper portion 7a and the forward taper portion 7b are formed so as to have a taper angle of 12 ° and a depth of 5 μm and 25 μm, respectively, in a state of being connected to the orifice plate 6 having a thickness of 30 μm.

In the evaluation of the ink ejection characteristics, as shown in FIG. 13, ink droplets ejected from each orifice 7 of the print head 3 are photographed from above using a high-speed camera, and are taken from the orifice 7 along the central axis X thereof. The amount of misalignment of the ink droplet that reached a plane 1 mm apart was measured as the ejection direction error. Specifically, the measuring device attached to the high-speed camera measures the displacement amount of the ink droplet from a microscope image obtained by photographing.

FIG. 14 shows the ink discharge characteristics of the orifice 7 shown in FIG. 12A, and FIG. 15 shows the ink discharge characteristics of the orifice 7 shown in FIG. here,
The horizontal axis represents the number of the ink chamber, and the vertical axis represents the displacement amount.

When the print head 3 has an orifice plate 6 in which a plurality of orifices 7 having the shape shown in FIG. 12A are arranged, the arrival point of the ink droplet, that is, the dot printing position is changed as shown in FIG. 7 deviates by more than ± 20 μm from the central axis. This is 20 mr
This corresponds to an ejection direction error of “ad”. For example, 300d
When one row of dots is printed at an image density of pi, a dot defect of only about 10 μm causes the dot to be visually recognized as a line defect.

Therefore, since the orifice 7 having the shape shown in FIG. 12A has a large ejection direction error as described above, the orifice plate 6 having this orifice 7 has a large error.
However, even if a dot image is printed using the print head 3 that uses, good image quality cannot be obtained.

When the print head 3 has the orifice plate 6 in which a plurality of orifices 7 having the shape shown in FIG. 12B are arranged, the arrival point of the ink droplet, that is, the dot print position is changed to the orifice as shown in FIG. 7 is within ± 5 μm at the maximum from the central axis. This is ± 5mra
This corresponds to an ejection direction error of d. According to FIG. 15, it can be seen that the dispersion of the flight direction error is small and stable. This is considered to be because the reverse tapered portion 7a more smoothly discharges the ink pushed out from the forward tapered portion 7b as ink droplets.

Incidentally, the ejection voltage E required for the ink ejection mechanism AC to eject ink is changed to the reverse taper portion 7a.
As a result, the results shown in FIG. 16 were obtained. Here, the depth of the reverse tapered portion 7a is equal to the orifice plate 6, that is, the liquid-repellent film 13 and the resin plate 1.
4 is shown as a ratio to the thickness of the laminate. According to this measurement result, it can be seen that the discharge voltage E increases as the depth W of the reverse tapered portion 7a increases. Therefore, it is preferable that the depth W of the reverse tapered portion 7a is short in order not to increase the ejection voltage E.

When the occurrence ratio of the ejection direction error exceeding ± 5 mrad with respect to the depth W of the inverse tapered portion 7a was measured, the result shown in FIG. 17 was obtained. Also here, the depth W of the reverse tapered portion 7a is shown as a ratio to the thickness of the orifice plate 6, that is, the thickness of the laminate of the liquid-repellent film 13 and the resin plate 14.

The occurrence ratio of the ejection direction error is acceptable if it is 2% or less of the whole. In this case, the depth W of the inverted tapered portion 7a is 0 <W <30 of the thickness of the orifice plate 6.
%. Further, in consideration of the increase in the ejection voltage described above, the depth W of the reverse tapered portion 7a is 0 <W
<20% of the thickness of the orifice plate 6 is preferable. In this case, the rate of occurrence of the ejection direction error is 1% or less of the whole, so it can be said that this is optimal.

As described above, the orifice 7 is
As shown in (b), the reverse tapered portion 7a and the forward tapered portion 7b
When there is a constriction constituted by the following formula, there is a tendency that apparently high straightness is obtained in the flight of ink droplets. This tendency was substantially the same even when the orifice 7 had the straight portion 7c shown in FIG. 9B instead of the reverse tapered portion 7b.

As described above, one process of irradiating the orifice plate 6 with a laser beam having a constricted beam shape can be performed by a single process.
Since the reverse taper portion 7a and the forward taper portion 7b are formed at the same time, no alignment error occurs between the reverse taper portion 7a and the forward taper portion 7b. Therefore, the processing operation for forming the orifice 7 on the orifice plate 6 is facilitated, and the processing accuracy can be improved. In addition, the straightness of the ink droplet flying from the orifice 7 is improved, and the ejection accuracy of the ink droplet is improved. Can be done.

Further, the orifice plate 6 is fixed to the head body 5 of the print head 3 with an adhesive, and then the orifice plate 6 is irradiated with a laser beam to form the orifice 7, thereby preventing the orifice 7 from being clogged by the adhesive. it can.

The depth W of the reverse tapered portion 7a of the orifice 7 can be set by moving the position of the laser beam condensing surface along the thickness direction of the orifice plate 6, so that the ink droplets fly. The orifice 7 can be easily formed in an optimum shape for realizing high straightness.

The orifice 7 similar to that of this embodiment is used.
Although laser light can be applied to the orifice plate 6 from the ink inflow side to form the laser beam, irradiating the laser light from the ink discharge side facilitates control of the laser light and can further improve processing accuracy. . In particular, since the orifice 7 requires a fine pore diameter in the order of microns, easy control of laser light is an important advantage. When the ink chamber of the head body 5 is closed at the end opposite to the orifice plate 6, laser light cannot be irradiated from the ink inflow side, so that it is important to irradiate laser light from the ink discharge side. Is a great advantage.

In this embodiment, the case where the liquid repellent film 13 is provided on the surface of the orifice plate 6 has been described. However, even when the liquid repellent film 13 is not provided on the surface of the orifice plate 6, the forward tapered portion 7b In the orifice 7 having not only the inverted tapered portion 7a but also the inverted tapered portion 7a, the result that the straightness in the ink ejection is high was obtained similarly to the result shown in FIG.

While the orifice plate 6 having the liquid-repellent film 13 can achieve continuous ejection for 10 minutes or more,
In the orifice plate 6 where the liquid-repellent film 13 is not formed, water is not repelled.
And the ink was clogged in the orifice 7 by continuous ejection for about 4 minutes.

Therefore, in the case of continuous discharge for a long time, it is preferable to use the orifice plate 6 provided with the liquid-repellent film 13.

Further, in this embodiment, the manufacturing method for forming the orifice 7 by irradiating the laser beam after fixing the orifice plate 6 to the front surface of the head body 5 has been described, but it is not necessarily limited to this. Instead, the orifice plate 6 formed in a predetermined shape is irradiated with a laser beam in the same manner as in the embodiment to form an orifice in a predetermined shape, and then the orifice plate 6 is fixed to the head body 5. May be used to manufacture the print head 3.

[0078]

As described in detail above, according to the first to fifth aspects of the present invention, each orifice has an ink ejection direction error of ± 5 mra with respect to the center axis of the orifice.
Since there is a constriction limited to d or less, it is possible to provide a print head capable of improving print resolution without lowering print quality.

According to the present invention, the forward tapered portion gradually narrows to a predetermined opening size from the ink inflow side to the ink ejection side in the thickness direction of the orifice plate, and the forward tapered portion. By forming a non-forward tapered portion connected to the orifice at the same time, the orifice can be constricted, so that it is possible to provide a method of manufacturing a print head capable of improving print resolution without deteriorating print quality.

According to the fourteenth aspect of the present invention, the forward tapered portion gradually narrows to a predetermined opening size from the ink inflow side toward the ink discharge side in the thickness direction of the laminate, and is connected to the forward tapered portion. An orifice plate used in a print head that can improve print resolution without deteriorating print quality because it has a constriction constituted by a non-forward tapered portion having a depth within 30% of the thickness of the laminate. provide.

According to the fifteenth aspect of the present invention, the forward tapered portion gradually narrows to a predetermined opening size from the ink inflow side to the ink discharge side in the thickness direction of the laminate, and is connected to the forward tapered portion. By simultaneously forming a non-forward tapered portion having a depth of 30% or less of the thickness of the laminate, the orifice can be constricted, so that the print resolution can be improved without deteriorating the print quality. A method of manufacturing an orifice plate used for a print head that can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of an inkjet print unit according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the print head according to the embodiment.

FIG. 3 is a diagram showing a configuration of a hole processing apparatus used for manufacturing a print head according to the embodiment.

FIG. 4 is a diagram showing a configuration of an optical system provided in the hole processing apparatus shown in FIG. 3;

FIG. 5 is a diagram schematically showing a configuration of a cylindrical lens in FIG. 4;

FIG. 6 is a sectional view showing a structure of an orifice plate before an orifice is formed by the hole drilling device in FIG. 3;

7 is a cross-sectional view illustrating an orifice formed by irradiating the orifice plate shown in FIG. 6 with a laser beam.

FIG. 8 is a sectional view for explaining the whole process of forming the orifice in the embodiment.

9 is a cross-sectional view for explaining an orifice formed to have a straight portion by irradiating a laser beam having a narrow beam shape to the orifice plate shown in FIG. 6;

FIG. 10 is a cross-sectional view for explaining an orifice obtained when the light-collecting surface position of the laser beam irradiated on the orifice plate shown in FIG. 6 is shifted toward the ink ejection side.

FIG. 11 is a cross-sectional view for explaining an orifice obtained when the position of the light-converging surface of the laser beam applied to the orifice plate shown in FIG. 6 is shifted toward the ink inflow side.

FIG. 12 is a cross-sectional view showing an orifice having only a forward tapered portion and an orifice having a forward tapered portion and a reverse tapered portion used for evaluating ink ejection characteristics.

FIG. 13 is a diagram for explaining an ink ejection evaluation method.

FIG. 14 is a view showing ink ejection characteristics of an orifice having only a forward tapered portion.

FIG. 15 is a view showing ink ejection characteristics of an orifice having a forward tapered portion and a reverse tapered portion.

FIG. 16 is a diagram showing the relationship between the depth of a reverse taper portion of an orifice having a forward taper portion and a reverse taper portion and discharge voltage.

FIG. 17 is a diagram showing the relationship between the depth of the reverse taper of an orifice having a forward taper and a reverse taper and the rate of occurrence of ink ejection errors.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ink-jet printing unit 3 ... Print head 5 ... Head body 6 ... Orifice plate 7 ... Orifice 12 ... Ink chamber

Continued on the front page (72) Inventor Masashi Shimozato 6-78, Minamicho, Mishima-shi, Shizuoka Toshiba Tec Corp. Mishima Plant (72) Inventor Hiroshi Ito 33 Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref. F-term in Toshiba Production Technology Center (reference) 2C057 AF30 AF33 AG07 AG09 AG44 AP12 AP23 AP25 AP60 BA03 BA14

Claims (15)

[Claims] 1. An orifice plate having a plurality of orifices arranged as ink discharge holes, and a plurality of ink chambers for guiding ink to the plurality of orifices, respectively, and integrated with the orifice plate to reduce the pressure of each ink chamber. A head body for discharging ink from the corresponding orifice by increasing the size of each orifice, wherein each of the orifices has a constriction that limits an error in the ink discharge direction with respect to a center axis of the orifice to substantially ± 5 mrad or less. And print head. 2. The constriction includes a forward tapered portion gradually narrowing to a predetermined opening size from an ink inflow side to an ink ejection side in a thickness direction of the orifice plate, and a non-forward tapered portion connected to the forward tapered portion. The print head according to claim 1, wherein: 3. The non-forward tapered portion is a straight portion having an opening size substantially equal to a predetermined opening size from an ink inflow side to an ink discharge side in a thickness direction of the orifice plate. Printhead as described. 4. The non-forward tapered portion is a reverse tapered portion that gradually widens from a predetermined opening size from an ink inflow side to an ink discharge side in a thickness direction of the orifice plate. Print head. 5. The print head according to claim 2, wherein the depth of the non-forward tapered portion is within 30% of the thickness of the orifice plate. 6. The print head according to claim 2, wherein the orifice plate includes a water-repellent layer formed as an ink ejection side surface and surrounding the non-forward tapered portion. 7. A bonding step of bonding an orifice plate to a head body defined by a plurality of ink chambers with an adhesive, and a step of arranging ink discharge holes communicating with the plurality of ink chambers and increasing the pressure of the ink chambers. An opening step of forming a plurality of orifices for ejecting ink on the orifice plate by irradiating a laser beam, wherein the opening step uses an imaging optical system in which a condensing surface is set inside the orifice plate. A forward taper portion which condenses the laser light and gradually narrows to a predetermined opening size from an ink inflow side toward an ink ejection side in a thickness direction of the orifice plate; and a non-forward taper connected to the forward taper portion Including a shaping step of constricting the orifice by simultaneously forming a portion. A method for manufacturing a print head, comprising: 8. The method according to claim 7, wherein the opening step is performed after the bonding step. 9. The method according to claim 7, wherein the laser beam is applied to a surface of the orifice plate on the ink ejection side. 10. The orifice plate has a water-repellent film as an ink ejection side surface, and the shaping step is a step of irradiating a laser beam with the protective film adhered to the water-repellent film and removing the protective film after the irradiation. The method for manufacturing a print head according to claim 7, comprising: 11. The apparatus according to claim 7, wherein the depth of the non-forward tapered portion is adjusted by moving the position of the light-converging surface set by the imaging optical system in the thickness direction of the orifice plate. Print head manufacturing method. 12. The non-forward tapered portion is a straight portion having an opening size substantially equal to a predetermined opening size from an ink inflow side to an ink discharge side in a thickness direction of the orifice plate. A method for manufacturing the print head described in the above. 13. The tapered portion according to claim 7, wherein the non-forward tapered portion is a reverse tapered portion that gradually widens from a predetermined opening size from an ink inflow side to an ink ejection side in a thickness direction of the orifice plate. Print head manufacturing method. 14. A laminate of a resin plate and a liquid-repellent film covering the resin plate, and a plurality of orifices arranged as ink ejection holes in the laminate, wherein each of the orifices is arranged in a thickness direction of the laminate. A forward tapered portion that gradually narrows to a predetermined opening size from the ink inflow side toward the ink discharge side, and a non-forward tapered portion connected to the forward tapered portion and having a depth of 30% or less of the thickness of the laminate. An orifice plate characterized by having a constricted shape. 15. A laminating step of forming a laminated body of a resin plate and a liquid-repellent film, and an opening step of forming a plurality of orifices arranged as ink discharge holes in the laminated body by irradiating a laser beam. The laser beam is condensed using an imaging optical system in which a light condensing surface is set inside the laminate, and a predetermined opening is formed from the ink inflow side toward the ink discharge side in the thickness direction of the laminate. The orifice is constricted by simultaneously forming a forward taper portion gradually narrowing to a size and a non-forward taper portion connected to the forward taper portion and having a depth of 30% or less of the thickness of the laminate. A method for manufacturing an orifice plate, comprising a shaping step.