JPH0315555A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To achieve miniaturization and making high density of an ink jetting nozzle by a method wherein an ink nozzle plate having a plurality of the jetting nozzles, a cavity plate having an ink pressurizing chamber, a diaphragm part, and a vibration plate having a projection part are bonded by lamination. CONSTITUTION:An ink nozzle 2 is formed to an ink nozzle plate 1 composed of glass, metal, etc. An ink pressurizing chamber 4, an ink passage 5, and an ink well 6 interconnected to both abovementioned are formed to a cavity plate prepared by organic photosensitive resin. A vibration plate 7 is composed of a SiO2 film part 8 as a diaphragm, a Si part 9, and a Si projection part 10. In such a structure, a piezoelectric actuator 11, when a pulse state voltage is applied thereto, is displaced to push the Si protection part 10. The SiO2 film part 8 is also displaced following that to make a volume of the ink pressurizing chamber 4 formed inside the cavity plate 3 vary. Therefore, ink corresponding to this variation content in volume is discharged outside from the ink nozzle 2.

Description

[Detailed description of the invention] [Industrial application field]

The present invention particularly relates to an inkjet recording head that is designed to be smaller and have a higher density of ink ejecting nozzles.

[Conventional technology]

2. Description of the Related Art Inkjet recording is conventionally known in which recording is performed by ejecting ink from fine nozzle holes and depositing it on a recording medium such as paper. One of the principles behind this is the on-demand type inkjet recording head. Usually, in this type of recording head, as shown in the exploded perspective view of FIG. 13, a substrate 3l made of stainless steel or glass, etc.
Ink nozzle 32, ink passage 33, ink pressurization chamber 34
, a groove such as an ink supply path 35 is formed by means such as etching or machining, and a diaphragm (cover plate) 36 is formed thereon.
The ink flow path is constructed by stacking and bonding or diffusion bonding. Furthermore, a piezoelectric element 37 serving as an electromechanical transducer is bonded to an external position of the diaphragm 36 corresponding to the ink pressurizing chamber 34, and an ink supply hole 38 is provided in a part of the diaphragm 36. There is. Electrodes are formed on the upper and lower surfaces of the piezoelectric element 37, and when an electric signal is applied to the electrodes, distortion occurs in the piezoelectric element 37 and the diaphragm 36 is displaced. As a result, the ink pressurizing chamber 3
4 decreases, and as a result, ink droplets are ejected from the ink nozzle 32 to perform recording. This type of on-demand inkjet recording head has a simple structure, so it can be manufactured compactly and at low cost.
It has the advantage of low noise. However, in the above-mentioned recording head, it is difficult to arrange a large number of ink nozzles in a line at high density due to limitations in the head structure and manufacturing technology, and the number of nozzles is usually 12 or 24. On the other hand, FIG. 14 is a sectional view of one ink nozzle of an on-demand type ink jet recording head previously proposed by one of the inventors (Japanese Patent Application No. 63-33470). In this other conventional recording head, an ink pressurizing chamber 42 and an ink passage 43 are formed by etching or the like on a cavity plate 41 made of metal or forceps.
, an ink supply path 44 is formed, and a diaphragm 45 is provided on both sides of the ink supply path 44.
, the nozzle plate 46 is joined by means such as adhesive or diffusion bonding. The nozzle plate 46 is provided with an ink nozzle 47 having a hole diameter of approximately 30 to 80 μm. A piezoelectric element 37 as an electromechanical transducer is fixed on the vibration plate 45 corresponding to the ink pressurizing chamber 42 by adhesive or other method. The ink ejection principle of this recording head is the same as described above.

[Problem to be solved by the invention]

As explained above, in the conventional technology, the ink nozzles 32 of the recording head shown in FIG.
It is possible to arrange the ink nozzles 32 at a distance of about 5 mm, and if the ink nozzles 32 are arranged in a staggered manner on the front and back surfaces of the head, eight nozzles can be formed per 1 mm. However, in the structure shown in FIG. 13, the maximum number of ink nozzles 32 that can be arranged is approximately 24, and if multi-nozzle configuration is required from the viewpoint of increasing printing speed, it is difficult to meet this requirement. On the other hand, in the recording head having the structure shown in FIG. 14, the ink pressurizing chamber 42 and the ink nozzles 47 are vertically connected, so that an extremely large number of ink nozzles 47 can be arranged on a plane. . However, there is a limit to the miniaturization of the piezoelectric element 37 as an electromechanical transducer, and the spacing between the ink nozzles 47 is limited to approximately 11.
It has the disadvantage that high density is difficult. Currently, inkjet recording heads are required to have multiple nozzles, high density, and durability. There is a strong desire to improve the manufacturing yield rate. A first object of the present invention is to provide an inkjet recording head which solves the problems of the conventional technology and which is made smaller and has a higher density of ink ejecting nozzles. It is an object of the second and third inventions to provide an inkjet recording head that solves the above-mentioned problems of the conventional technology and is designed to be smaller in size, more durable, and to have an improved manufacturing yield rate. The purpose of the fourth invention is to solve the problems more than those of the conventional technology, to achieve miniaturization, improve durability, and manufacturing yield rate, as well as to improve assemblability and positioning accuracy of parts. An object of the present invention is to provide an inkjet recording head that achieves the following.

[Means to solve the problem]

An inkjet recording head according to a first aspect of the present invention includes: an ink nozzle plate having a plurality of ink ejection nozzles; a cavity plate having an ink pressurizing chamber coaxially with each nozzle; a diaphragm portion; and an integral part of the diaphragm portion. a diaphragm having a protrusion arranged coaxially with each ink pressurizing chamber, and are laminated and joined in the above order with each protrusion on the outside,
The end face of each protrusion is configured to be pressed by a piezoelectric actuator. In the inkjet recording head according to the second invention, the diaphragm is made of a metal material. In the inkjet recording head according to the third invention, the diaphragm is made of a thin film-like member made of an organic material having elasticity and ink resistance. The inkjet recording head according to the fourth invention includes a vibration transmitting member as a protrusion fixed to the bottom surface of a recess formed in a position where the vibration plate is coaxial with the ink pressurizing chamber.

[For use]

In the inkjet recording head according to the first invention, the diaphragm portion of the diaphragm can be made thin, so it can be sufficiently displaced with a small pressing force, and the cavity plate can also be made thin, so the volume of the ink pressurizing chamber can be reduced. Since the nozzle is directly connected to this, ink is ejected from the nozzle by pressing the end face of the protrusion with a piezoelectric actuator. In the inkjet recording head according to the second invention, the diaphragm made of a metal material has excellent mechanical strength and good durability against repeated displacement. Moreover, the electroforming method allows the diaphragm to have a fine protrusion shape. In the inkjet recording head according to the third invention, the diaphragm made of an organic material having elasticity and ink resistance has excellent mechanical strength and durability against repeated displacement, similar to the above-mentioned second invention. is also good. In the inkjet recording head according to the fourth aspect of the invention, the vibration transmitting member is easily fixed because its fixed location is the bottom surface of the recess formed in the diaphragm, and there is also a dimensional adjustment margin for alignment with the piezoelectric actuator. This improves alignment accuracy.

【Example】

Embodiments of the present invention will be described below based on the drawings. 1 to 6 are diagrams showing an embodiment according to the first invention. Figures 1 to 3 are a plan view (each figure (a)) and a sectional view (each figure (a)) of the structural member of the embodiment according to the first invention.
b)). FIG. 1 shows an ink nozzle plate 1 made of glass, metal, etc., on which ink nozzles 2 are formed. Figure 2 shows a cavity plate 3 made of organic photosensitive resin. The cavity plate 3 has an ink pressurizing chamber 4.
, an ink passage 5, and an ink reservoir 6 communicating with the former two. By using an organic photosensitive resin, microfabrication by etching becomes possible. FIG. 3 shows a diaphragm 7, and the diaphragm 7 is a SiO film portion 8 as a diaphragm.
, the St part 9 and the Si protrusion part 10. This diaphragm 7 can be manufactured by a similar method according to semiconductor device manufacturing technology. FIG. 4 is a cross-sectional view of a complete recording head made by laminating and integrating the structural members shown in FIGS. 1 to 3 using a well-known method, and FIG. 5 is a longitudinal cross-sectional view thereof. 11 in FIGS. 4 and 5 is a piezoelectric actuator. This piezoelectric actuator 11 is of a conventionally known bimorph type. Either unimorph type may be used, and the former is more advantageous when generating force at low voltage is required. In this structure, when a pulse voltage is applied to the piezoelectric actuator 11, the piezoelectric actuator 11 is displaced and presses the Si protrusion 10. Along with this, the Si02 film portion 8 is also displaced, changing the volume of the ink pressurizing chamber 4 formed inside the cavity plate 3, so that ink corresponding to this volume change is directed from the ink nozzle 2 to the outside. is discharged. FIG. 6 is an enlarged sectional view of the main part of the embodiment according to the first invention. An example of the dimensions of each part is as follows. Diameter (DI) of ink nozzle 2: 40 μm Ink pressure chamber 4
Diameter (D2): 140 μm Thickness of ink nozzle plate 1 (AI): 50 μm Thickness of cavity plate 3 (A2)
: 20μmSin. Thickness of membrane portion 8 (A3): 1.
8μm Thickness of Si part 9 (A4): 50)tm
Height (A5) of Si protrusion 10: 100 pm In the embodiment according to the first invention, the above dimensions are sufficient, so the interval between the ink nozzles 2 is 170 pm.
If the ink nozzles are arranged in two rows in a staggered manner with this spacing, the spacing will be 85 μm.
m, and it is possible to form 12 lines per 1 mm. Furthermore, since the ink pressurizing chamber and the 9 10 ink nozzle are directly connected, it is easy to use multiple nozzles according to the intended purpose. In addition, the ink nozzle diameter of the embodiment according to the first invention is approximately 40 μm, and the ink pressurizing chamber has a depth of 10 to 50 μm, which is extremely finely processed, and the volume of the bubbles is generally larger than this. It is difficult for air bubbles to enter from outside the ink nozzle, and it is highly reliable as a recording head. The form of the piezoelectric actuator used in the embodiment according to the first invention varies depending on the shape of the Sin2 film part and the Si projection part, but if the recording head has the above dimensions, it is of the following bimorph type. Sufficient ink ejection can be guaranteed. Length of bimorph: 4 tnm Thickness of bimorph: 0.53 mm Width of bimorph: 0.12 mm Drive voltage of bimorph: IOOV As is clear from the above description, in the embodiment according to the first invention, compared to the conventional device The distance between the nozzle ink pressurizing chamber and the protrusion can be narrowed, so the nozzle density can be increased, and the entire device can be made smaller. Next, an embodiment according to the second invention will be described. 7th
11 through 11 are diagrams showing an embodiment according to the second invention. The difference from the first invention described above is that the diaphragm is made of a metal material to improve durability and manufacturing yield. That is, the first invention is superior to the conventional device in terms of multi-nozzle design and high resolution, but the Sing film portion 8
has almost no plastic deformability and its thickness is 1 to 3
mm, it is easy to break during the assembly process and there is a risk that the manufacturing yield will be poor. Additionally, changes in finish such as etching can easily cause variations in durability (continuous displacement characteristics). Therefore, in the embodiment according to the second invention, an apparatus configuration as described below is adopted. FIG. 7 is a perspective view of an ink nozzle plate 1, on which ink nozzles 2 having a diameter of 30 to 80 μm are formed at predetermined intervals. The material of the ink nozzle plate 1 is metal. Either glass or plastic may be used. 1l 12 FIG. 8 is a perspective view of a cavity plate 3 made of an organic photosensitive resin film that can be microfabricated by etching, and includes an ink pressure chamber 4, an ink passage 5. ink pond 6
etc. are formed. FIG. 9 is a perspective view of a diaphragm 7 made of metal foil with a thickness of 1.
2, a protrusion 14 and a reinforcing portion 13 formed by electroforming, corresponding to the pitch of the ink nozzle 2 and the ink pressurizing chamber 4.
is provided. The two holes provided in the diaphragm 7 are
This is an ink supply hole 7A for supplying ink to the cavity plate 3 from an external ink tank (not shown). FIG. 1O shows the configuration of the bimorph piezoelectric actuator l1, and this bimorph piezoelectric actuator 11 is
It has a structure in which piezoelectric elements 11A and IIB are adhered to both sides of a metal plate 11C. The piezoelectric actuator 11 is machined with slits corresponding to the spacing between the projections l4 of the diaphragm 7. FIG. 11 is a sectional view of an embodiment according to the second invention in which lamination and integration have been completed. That is, the ink nozzle plate 1, the cavity plate 3. The diaphragms 7 are stacked in this order, and the piezoelectric actuator 1l is placed on the protrusion l4 of the diaphragm 7. Note that the right side portion of the piezoelectric actuator 11 is fixed by a member not shown. With this structure, when a voltage is applied to the piezoelectric actuator 1l, the piezoelectric actuator 11 is displaced in the direction of pressing the protrusion 14, reducing the volume of the ink pressurizing chamber 4, thereby causing ink to be ejected from the ink nozzle 2. . The approximate dimensions of each member of this recording head are as follows. Thickness of ink nozzle plate 1: O. OS~0. 1 mm Thickness of cavity plate 3: O. O3 - 0.08mm Thickness of diaphragm 7: 0.001 - 0.01mm Height of protrusion 14: Approx. 1 mm Various metal foils can be selected as the material for the diaphragm 7, but considering the combination with electroforming, nickel, stainless steel,
Iron, copper. Silver, gold, tantalum, titanium, etc. are preferable, and nickel is the most suitable material for the protrusion 10. 13 14 Since the thickness of the diaphragm 7 of the embodiment according to the second invention is 1 to 10 μm as described above, it can be displaced even with a very small force, and the width, thickness, etc. of the piezoelectric actuator can be extremely miniaturized. Therefore, in the configuration of this recording head, the pitch between the ink nozzles 2 can be narrowed to around 0.2 mm, and if the ink nozzles 2 are arranged in a staggered manner, the pitch can be reduced to about 0.8 mm. It is possible to achieve both high resolution and multi-nozzle design. Furthermore, since metal foil has plastic deformability, it has been experimentally confirmed that it does not break during assembly and has excellent ink ejection durability. As is clear from the above description, in the embodiment according to the second invention, it is possible to reduce the size and increase the density of the nozzle, and also to improve the durability, particularly the continuous displacement characteristics, and the manufacturing yield rate. Furthermore, an embodiment according to the third invention will be described. The difference between the third invention and the first invention is that, like the second invention described above, the diaphragm is made of an organic material that has appropriate elasticity and ink resistance. The aim is to improve manufacturing yield. Note that the embodiment according to the third invention will also be explained using FIGS. 7 to 11 used to explain the embodiment according to the second invention. 7 to 10 are perspective views of main structural members of an embodiment according to the third invention. Figure 7 shows ink nozzle plate 1.
2 is a perspective view of the ink nozzle 2, in which ink nozzles 2 having a diameter of 30 to 80 μm are formed at predetermined intervals. The material of the ink nozzle plate 1 may be metal, glass, or plastic. FIG. 8 is a perspective view of a cavity plate 3 made of an organic photosensitive resin film that can be microfabricated by etching, in which an ink pressure chamber 4, an ink passage 5, an ink reservoir 6, etc. are formed. . FIG. 9 is a perspective view of a diaphragm 7 made of a film of an organic material with a thickness of about 50 μm, and this diaphragm 7 is connected to the substrate portion 12.
corresponds to the pitch of the ink nozzle 2 and the ink pressurizing chamber 4,
A projection 14 serving as a vibration transmission rod and a reinforcing portion 13 serving as a support are fixed. The two holes provided in the diaphragm 7 are ink supply holes 7A for supplying ink to the cavity plate 3 from an outside ink tank (not shown). Although various organic films can be used as the diaphragm 7, an example will be described below in which a polyamide film with a thickness of 50 μm and whose surface is coated with Teflon of about 10 μm is used. First, an ink nozzle plate 1 and a cavity plate 3 having a predetermined shape are prepared.
are manufactured by a conventional method and joined by a known method. After sufficiently heating this to about 250°C, the diaphragm 7 made of the Teflon-coated polyimide film was heated.
is placed on the cavity plate 3, and the diaphragm 7 is attached to the cavity plate 3 while being rubbed with a separately heated metal flathead. After the pasting is completed, these are sandwiched between metal plates and bonded under heat and pressure. Through this series of steps, the cavity plate 3 and the diaphragm 7 can be bonded together without any air bubbles entering between them and without filling the ink supply path or the like. Furthermore, a vinyl chloride film with a thickness of about 50 to 100 ptn can be used as the diaphragm, and in this case, if the thermocompression bonding temperature is set to about 100 to 150°C, the polyvinyl chloride film can be A good diaphragm can be obtained as well. FIG. 10 shows the structure of the high-morph piezoelectric actuator 1. This bimorph type piezoelectric actuator 11 has piezoelectric elements 11A and II on both sides of a metal plate 11c.
It has a structure in which B is attached. Further, the piezoelectric actuator 1l is processed with slits corresponding to the spacing between the protrusions 14 of the diaphragm 7. FIG. 1l is a cross-sectional view of an embodiment according to the third invention in which lamination and integration have been completed. That is, the ink nozzle plate 1, the cavity plate 3. The diaphragms 7 are stacked in this order, and the piezoelectric actuator 11 is placed on the reinforcing portion 13 and the protrusion l4 of the diaphragm 7. Note that the right side portion of the piezoelectric actuator 1l is fixed by a member not shown. With this structure, when a voltage is applied to the piezoelectric actuator l1, the piezoelectric actuator 11 is displaced in the direction of pressing the protrusion 10, reducing the volume of the ink pressurizing chamber 4, thereby causing ink to be ejected from the ink nozzle 2. . 17 18 The diaphragm 7 made of the solid iron film according to the embodiment of the third invention has a thickness of about 50 μm as described above, and a Young's modulus of 300 kg/mm, so it can be easily pierced by even the slightest force. displacement, and the width and thickness of the piezoelectric actuator can be made extremely small.Of course, it also has excellent ink resistance.For this reason, in the embodiment according to the third invention, the pitch between the ink nozzles 2 is set to 0. It can be narrowed to around 2mm, and the ink nozzle 2
It has been experimentally confirmed that if the nozzles are arranged in a staggered manner, the pitch can be set to about 0.8 mm, and both high resolution and multi-nozzle design can be satisfied. As is clear from the above description, in the third invention as well, it is possible to reduce the size and increase the density of the nozzle, and also to improve the durability, especially the continuous displacement characteristics, and the manufacturing yield rate. Next, an embodiment of an inkjet recording head according to the fourth invention will be described with reference to FIG. 12. 1st
Figure 2 is a sectional view of the main parts of this embodiment, and this embodiment is the first
The difference from the embodiments according to the second and third inventions shown in FIG. 1 is the structure of the diaphragm. Note that the same members as in the embodiments according to the second and third inventions are given the same reference numerals. In FIG. 12, the material of the diaphragm 21 can be selected from metal, glass, Ceragox, plastic, etc., but here, metal with a thickness of several microns to several hundred or more microns is used. A recess 22 is formed in the diaphragm 21 by half etching. Note that the recess 22 can also be formed by joining a flat plate and a plate having through holes. 23 is a vibration transmission rod, which is made by precision cutting metal or quartz fiber. To assemble each member, first, ink nozzle plate 1, cavity plate 3, and diaphragm 2l are attached to ink nozzle 2. The ink pressurizing chamber 4 and the concave portion 22 of the diaphragm 21 are laminated with their positions adjusted so that they are coaxial, and are integrated by, for example, diffusion welding. After that, insert the vibration transmission rod 23 into the recess 22, and
Fix to the bottom of 2 with organic adhesive. At this time, the recess 2
2 and the vibration transmission rod 23 in the direction perpendicular to the axis, alignment is easy and the accuracy of alignment is improved by 19 to 20 degrees. The piezoelectric actuator 11 is mounted on the diaphragm 2 such that its tip is located on the upper end surface of the vibration transmission rod 23.
1 through a support plate 24.

【Effect of the invention】

According to the first invention, compared to the conventional technology, the nozzle, the ink pressurizing chamber. The intervals between the protrusions can be narrowed, so the density of the nozzles can be increased, and the inkjet recording head can be made smaller. In addition, if the diaphragm is made of a metal material or an organic material as in the second and third inventions, it is possible to reduce the size and increase the density of the nozzle, and improve durability, especially continuous displacement characteristics, and manufacturing yield rate. can be improved. In particular, by using a very thin organic film with a small Young's modulus as the diaphragm as in the third invention, this organic film diaphragm can be displaced with a very small force, so the shape of the piezoelectric actuator as a driving source is This has the advantage that it is possible to make the inkjet recording head extremely compact, and the ink pressurizing chamber can also be made small. Furthermore, since the organic film diaphragm used in the present invention has superior plastic deformability compared to St, etc., it has the effect that it hardly suffers from breakage during the assembly process and is excellent in repeated durability. Furthermore, according to the fourth invention, since the diaphragm is not easily damaged, the yield rate during manufacturing is improved, and since the diaphragm is provided with a recess, the vibration transmission member can be easily fixed.
In addition, since there is dimensional adjustment margin for alignment with the piezoelectric actuator, alignment accuracy is improved.

[Brief explanation of the drawing]

1 to 6 are views showing an embodiment according to the first invention, FIG. 1 shows an ink nozzle plate of the embodiment, FIG. 1A is a plan view thereof, and FIG. Its sectional view, FIG. 2, also shows its cavity plate, its plan view, FIG. a) is a plan view thereof, FIG. 7 is a cross-sectional view for explaining the dimensions of the main part of the embodiment, FIGS. 7 to 11 are diagrams showing embodiments according to the second and third inventions, and FIG. FIG. 8 is a perspective view of a cavity plate thereof, FIG. 9 is a perspective view of a diaphragm thereof, and FIG. 10 is a perspective view of an actuator thereof. Evening perspective view, No. 11
12 is a sectional view of the essential parts of the embodiment according to the fourth invention, FIG. 13 is an exploded perspective view of one conventional example, and FIG. I4 is another conventional example. FIG. Symbol explanation 1: Ink nozzle plate, 2: Ink nozzle, 3: Cavity plate, 4: Ink pressurizing chamber, 7: Vibration plate, 8: Sioz film part, 9: Si part, 10: Si protrusion, 1l: Piezoelectric Actuator, 12: Substrate part, 13: Reinforcement part, 2l: Vibration plate, 22: Recessed part, 23: Vibration transmission rod, 24:
Support plate.

Claims (1)

[Scope of Claims] 1) an ink nozzle plate having a plurality of ink ejection nozzles; a cavity plate having an ink pressurizing chamber coaxially with each of the nozzles; a diaphragm portion; a diaphragm having a protrusion disposed coaxially with each ink pressurizing chamber; is laminated and joined in the above order with each protrusion on the outside, and the end face of each protrusion is pressed by a piezoelectric actuator. An inkjet recording head characterized by: 2) The inkjet recording head according to claim 1, wherein the diaphragm is made of a metal material. 3) The inkjet recording head according to claim 1, wherein the diaphragm is a thin film-like member made of an organic material having elasticity and ink resistance. 4) The inkjet recording head according to claim 1, wherein the diaphragm includes a vibration transmitting member as a protrusion fixed to a bottom surface of a recess formed coaxially with the ink pressurizing chamber.