JP2001212960A - Ink-jet head, and method for forming actuator for ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet head with a shape memory alloy capable of easily forming an actuator used. SOLUTION: In an ink-jet head 2 comprising an elastic member 8 as at least a part of a wall providing an ink storage space 20, for pressuring a thin film- like shape memory material 14 memorizing a projecting shape, against the elastic member 8 so as to deform the shape memory material 14, reproducing the shape memorized in the shape memory material 14 so as to deform the elastic member 8 for reducing the capacity in the space 20, and thereby pressuring and ejecting the ink, the projecting-shaped shape memory material 14 is formed such that the surface of the projecting-shaped shape memory material 14 opposite to the side facing the elastic member 8 can be seen from the opposite side of the elastic member 8 at least in the state the memorized shape is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head and a method for forming an actuator used for the ink jet head.

[0002]

2. Description of the Related Art Various ink jet heads using a shape memory alloy as an actuator are known. Such an inkjet head has an ink chamber provided with a nozzle for discharging ink on a part of the outer wall. A part of another outer wall of the ink chamber is made of a shape memory alloy stored in a predetermined shape at high temperature (mother phase). Therefore, by transforming the shape memory alloy from normal temperature (martensitic phase) to high temperature or vice versa, the volume of the ink chamber is reduced or expanded, whereby the ink accommodated in the ink chamber passes through the nozzle. Fly outside.

[0003]

However, in practice, it is difficult to form a shape memory alloy. For example, in Japanese Patent Application Laid-Open No. H10-258508, a shape memory alloy is processed into a complicated shape, and this shape is heated to a high temperature. Need to be memorized. Therefore, the cost of manufacturing an ink jet head using such a shape memory alloy increases.

Accordingly, an object of the present invention is to provide an ink jet head using a shape memory alloy that can be easily formed as an actuator, and a method of forming the actuator.

[0005]

In order to achieve these objects, an ink jet head according to the present invention has a structure in which at least a part of a wall forming a space for accommodating ink is formed of an elastic member. The shape memory material is deformed by pressing a thin-film shape memory material having a convex shape memory onto the elastic member, and the elastic member is deformed by reproducing the shape memorized by the shape memory material. In an ink jet head that reduces the volume in the space and thereby pressurizes and discharges the ink, the convex shape memory material has an elasticity of the convex shape memory material at least in a state where the stored shape is reproduced. The surface opposite to the side facing the member is formed so that all parts can be seen from the opposite side of the elastic member.

In a method of forming an actuator for an ink jet head using a shape memory material, a first aspect of the present invention is as follows: (a) a planar first actuator having a predetermined thickness;
For the substrate, a slot having a slope having a predetermined inclination angle with respect to the thickness direction and forming a slot penetrating the substrate, as a result,
(B) making all of the slopes visible when viewing the slot from the substrate surface side;
Providing a second substrate at least on a back surface of the first substrate in a region where the slot is formed; and (c) a second substrate portion provided on the back surface of the first substrate in the slope and the region where the slot is formed. Forming a thin film of a shape memory material, (d) removing the second substrate from the first substrate, and (e) removing at least a region near the region where the slot is formed by a first process. Removing a predetermined thickness from the back surface of the substrate, thereby exposing a part of the shape memory material to the back side of the first substrate.

It is preferable to use a silicon wafer as the first substrate. In this case, the slope is {1} of silicon.
11} plane.

In a method of forming an actuator for an ink jet head using a shape memory material, a second aspect of the present invention is as follows: (a) forming a slot in a flat substrate having a predetermined thickness; Making the entire boundary surface of the slot visible when viewing the slot from the substrate surface side; (b) forming a thin-film shape memory material on the boundary surface of the slot; and (c). Removing a predetermined thickness from the back surface of the substrate at least in the vicinity of the region where the slot is formed, thereby exposing a part of the shape memory material to the back side of the substrate.

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3,
The inkjet head 2 according to the present invention generally includes a lower structure 11 having a nozzle plate 4, a channel plate 6, a first substrate 8, and a second substrate 10 (FIG. 3).
And third substrate 12, actuator 14, heating element 1
6, and an upper structure 19 having a fourth substrate 18 (FIG. 3)
It is composed of

(Configuration of Lower Structure) Channel Plate 6
Is formed of a plate of photosensitive glass or the like having a predetermined thickness, and elongated slots (ink channels 20) are formed in parallel at predetermined intervals, so that each ink channel 20 corresponds to its corresponding ink channel. A pair of longitudinally extending side walls 22 forming 20 are formed. In the present embodiment, only two ink channels 20 are formed in one channel plate 6, but more (eg, several hundred) ink channels 20 may be formed. These ink channels 2
A common ink chamber 24 is formed in the channel plate 6 at a predetermined distance from one end in the longitudinal direction of O (the upper end in FIG. 1). In order to connect each ink channel 20 to the common ink chamber 24, a groove (ink inlet 26) corresponding to each ink channel 20 is formed on the upper surface of the channel plate 6.

The nozzle plate 4 is provided with a nozzle 28 for connecting the other end (the lower end in FIG. 1) of each ink channel 20 in the longitudinal direction to the atmosphere.

The ink channel 20 is covered with a thin first substrate (partition 8) attached to the upper surface of the channel plate 6, and the common ink chamber 24 and the ink inlet 26 are covered with a third substrate 12. (See Figure 3)
Thereby, the ink channel 20, the common ink chamber 24,
Further, the ink 30 can be stored in the ink inlet 26.

The second substrate 10 includes a channel plate 6
Are provided on the upper surface of each side wall 22.

(Structure of Upper Structure) The third substrate 12 disposed above the second substrate 10 is made of a plate having a predetermined thickness, and has a predetermined inclination angle with respect to the thickness direction as described later. It has a slot 32 formed with a slope 32a and extending in the longitudinal direction (vertical direction in FIG. 2). Slot 32
Is formed in a region facing the ink channel 20 with the third substrate 12 attached to the second substrate 10, and the cross section of the slot 32 is
It is formed so as to become smaller toward the side.

Along the slope 32 of the third substrate 12, Ti
A thin plate (actuator 14) made of a shape memory alloy such as a Ni alloy is provided, and a part thereof is exposed below the slot 32. The length of the exposed actuator portion in the thickness direction is set to be larger than the thickness of the second substrate 10. The actuator 14 is formed in a high-temperature atmosphere by a known thin film forming technique (for example, sputtering). At the time when the formation of the thin film is completed, the bottom portion 14a of the exposed portion of the actuator 14 is flat as shown in FIG. However, the actuator 14 is transformed into a state shown in FIG.

The actuator 14 may be made of any shape memory alloy other than TiNi alloy, for example, Pd or Cd on TiNi.
It may be made of an alloy to which u or the like is added, or a Cu-Zn-Al alloy. Further, the actuator 14 does not need to be formed of metal, and may be made of a material other than metal, for example, a shape memory resin, a shape memory fiber, or a composite material thereof.

The fourth substrate 18 provided on the upper surface of the third substrate 12 (via the actuator 14) has a heating element (heater 16) facing the actuator 14 on the lower surface. The heater 16 is connected to a lead (not shown), and generates heat when a current flows through the lead. In the state where the third substrate 12 and the fourth substrate 18 are joined in the process of manufacturing the ink jet head, the heater 16 does not contact the bottom portion 14a of the heater 16 and the actuator 14 as shown in FIG. In the deformed state shown in FIG. 2A in which the substrate 10 and the third substrate 12 are joined, the heater 16 and the bottom 14a of the actuator 14 are set to be in contact with each other.

Next, an example of a method for manufacturing the ink jet head 2 will be described. The inkjet head 2 is
As best shown in FIG. 3, the lower structure 11 and the upper structure 19 are joined to each other, and a method of manufacturing the lower structure 11 and the upper structure 19 will be described below.

(Method of Manufacturing Lower Structure) Referring to FIG.
In the manufacture of the lower structure 11, grooves and depressions such as the ink channels 20 are formed by etching into the channel plate 6.
Formed. The nozzle plate 4 is attached below the channel plate 6 in which the grooves and the like are formed. At least on the ink channel 20 of the channel plate 6, a partition wall 8 made of an elastic material such as polyimide is adhered, and a second wall made of copper or the like is formed on the opposite side of the side wall 22 of the channel plate 20 across the partition wall 8. The substrate 10 is attached.

(Method of Manufacturing Upper Structure) Next, an example of a manufacturing process of the first portion 38 having the third substrate 12 and the actuator 14, which is a part of the upper structure 19, will be described with reference to FIG. . First, a single plate made of a single-crystal silicon wafer having a predetermined thickness (for example, 20 μm) [surface is (100) plane, orientation flat is (110) plane]
[FIG. (A)] is placed in a thermal oxidation furnace and oxidized to form a SiO ₂ film having a thickness of, for example, 0.2 μm on both surfaces (FIG. (B)).
This plate corresponds to the third substrate 12 as described later.
Next, a thin film of Si ₃ N ₄ (for example, 0.07 μm) is formed on both surfaces by a plasma CVD method (FIG. 3C). Next, after a mask pattern is formed on the upper surface using a photoresist (not shown), Si ₃ N ₄ and SiO ₂ are etched using RIE (reactive ion etching).
A plurality of Si ₃ at predetermined intervals (for example, 100 μm)
N ₄ and SiO ₂ portions are formed [FIG. Subsequently, the inclined surface 32a of the third substrate 12 is obtained by performing wet etching using potassium hydroxide on the upper surface of the plate.
[Figure (e)]. The slope 32a is a (111) plane, and forms an angle of 55 ° with a horizontal direction orthogonal to the thickness direction. Further, the shape memory alloy TiNi (Ti:
A Ni composition ratio of about 1: 1) is formed into a film having a thickness of, for example, 5 μm by sputtering [FIG. Subsequently, the plate is annealed in a vacuum furnace at 500 ° C. for 1 hour. Finally, after a mask pattern is formed on the upper surface using a photoresist (not shown), TiNi is etched using a solution having a hydrofluoric acid: nitric acid: water ratio of 1: 1: 4, thereby forming a predetermined interval. A plurality of opened TiNi portions (this corresponds to the actuator 14) are formed [FIG.

Next, an example of a manufacturing process of the second portion 40 having the heater 16 and the fourth substrate 18, which is the remaining portion of the upper structure 19, will be described with reference to FIG. Next time,
Apart from the silicon wafer, a predetermined thickness (for example, 20
μm) single crystal silicon wafer [surface is (110) plane,
On a single plate [FIG. (A)] having an orientation flat of (100) surface], for example, a 1 μm-thick Au film is formed on one surface (lower surface in the drawing) by sputtering.
[Figure (b)]. This plate corresponds to the fourth substrate 18. Next, after forming a mask pattern using a photoresist (not shown) on the lower surface, an Au etching solution (Wako Pure Chemical Industries, Ltd.)
Au is etched into an electrode pattern using the method shown in FIG. Finally, ruthenium oxide (Ru)
The ₂ O) based paste, by applying a screen having a predetermined shape is provided on the Au layer (i.e. by performing the well-known screen printing), formed, for example, a heater 16 having a thickness of 10μm between Au electrodes [Figure (d)]. In addition,
As shown in FIG. 5E, in the present embodiment, the electrodes are formed in a plurality of lines (for example, a width of 50 μm and an electrode interval of 2 μm).
73 μm), and after a part of each electrode line is removed by etching, a heater (for example, 6 μm)
0 μm × 60 μm).

Finally, a method of finally manufacturing the upper structure 19 will be described with reference to FIG. First, the first part 38 and the second part 40 are connected to the actuator 1 of the first part 38.
After the heater 16 of the second portion 40 is positioned so as to face the concave portion of FIG. 4 [FIG.
[Figure (b)]. At this time, the linear electrodes are arranged to extend in a direction perpendicular to the plane of the paper. The Si ₃ N ₄ and SiO ₂ on the lower surface of the plate thus obtained are simultaneously removed by etching using RIE [FIG. Finally, the silicon on the lower surface is made to have a predetermined thickness (for example, 10
μm), and the actuator 14 T
The upper structure 19 is formed so that a part of the iNi is exposed from the silicon substrate, that is, the third substrate 12 (FIG. 4D).

FIG. 2 (a) shows a state in which the lower structure 11 and the upper structure 19 are bonded together as shown in FIG. Specifically, as described above, the actuator 14
Since the length of the exposed portion in the thickness direction is set to be larger than the thickness of the second substrate 10, in a state where the second substrate 10 is bonded to the third substrate 12 at room temperature (at this time, The shape memory alloy constituting the actuator 14 includes:
A martensitic phase has been induced. 2), the partition wall 8 forming a part of the boundary of the ink channel 20 pushes and deforms the actuator 14 upward, and as a result, the actuator 14 is in contact with the heater 16.

(Operation of Inkjet Head) FIGS.
In the ink jet head 2 manufactured as described above, the ink 30 is filled in each ink channel 20 and the nozzle 28 from a not-shown ink tank via a common ink chamber 24 and an ink inlet 26. . In this state, that is, in the state shown in FIG. 2 (a), when the heater 16 is energized and heated, the temperature of the actuator 14 rises.
Returns to the planar shape as shown in FIG. As a result, FIG.
As shown in (b), the partition (elastic member) 8 is pushed downward, whereby the ink 30 in the corresponding ink channel 20 is pressurized, and the ink 30 from the corresponding nozzle 28 is pressed.
Is discharged. Subsequently, when the energization of the heater 16 ends, the actuator 14 drops below the transformation temperature and enters the normal temperature state. As a result, the actuator 14 transforms from the parent phase to the martensite phase, and the restoring force of the partition 8 causes
The state before the heating is restored (FIG. 2A). At this time, a negative pressure is generated in the ink channel 20, and the ink 30 is replenished from the common ink chamber 24 through the ink inlet 26 by the suction force.

Although the embodiment of the ink jet head according to the present invention has been described above, the present invention is not limited to this and can be variously modified. For example, in the above-described embodiment, the actuators 14 are heated via the heaters 16, but instead, each actuator 14 is connected to a lead unit (not shown) and directly individually applies a voltage corresponding to an image signal. It may be made to be heated by the thing.

The material and configuration of the partition 8 are not limited to those in the above embodiment as long as the partition 8 can urge the actuator 14 upward. However, SUS is preferred from the viewpoint of corrosion resistance to the ink 30.

Further, in the above embodiment, the position of the heater 16 for heating the actuator 14 is opposite to the partition 8 with the actuator 14 interposed therebetween. However, the present invention is not limited to this. 14
It may be arranged between the partition 8 and the like.

The slope 32a of the third substrate 12 can also be obtained by general fine processing such as pressing, for example, and in this case, the slope 32a can be formed at any inclination angle. In addition, it is also possible to use a dent formed on the substrate by isotropic etching, form a thin film of a shape memory material in this dent, and use the film for an actuator. In any case, the obtained actuator is
The surface opposite to the partition (elastic member) which is a part of the wall of the ink channel is formed so that all parts can be seen from the opposite side of the elastic member, and the edge portion is substantially formed in the shape memory material. Must not exist. The reason is that if an edge portion is present in the shape memory material, the deformation is concentrated on the edge portion when the shape memory material is deformed, which causes a problem that fatigue occurs in the shape memory material. This deformation concentration increases as the angle between the bottom surface 14a of the actuator 14 and other portions (125 ° in the above embodiment) decreases.

FIG. 7 shows a part of a printer 100 in which the ink jet head 2 is incorporated. This printer 100
A bottom plate 102, a pair of support walls 104 extending substantially perpendicularly from the bottom plate 102 and facing each other;
And a front wall 106 connecting the Outside the front wall 106, a paper feed tray 108 for storing a sheet (paper) S to be printed by the printer 100 is provided, and the sheet S stored in the paper feed tray 108 is formed on the front wall 106. The printer 1 is connected via a paper feed port (not shown)
00 is supplied inside.

Inside the front wall 106, a pair of support walls 10
4, an upper guide rail 112 parallel to the front wall 106 and a lower guide rail 114 disposed below the upper guide rail 112 are supported. On these guide rails 112 and 114, an ink cartridge 116 is movably supported. Insert the ink cartridge 116 into the guide rails 112 and 114
The scanning mechanism 118 that reciprocates along a pair of the pulleys 120 supports a pair of pulleys 120 supported inside the front wall 106 near the respective support walls 104 and a belt 122 wound around these pulleys 120. And a motor (not shown) for rotating the pulley 120 forward and reverse.
The ink cartridge 116 is connected to a part of the second cartridge 2.

In the present embodiment, the ink cartridge 116 has one or a plurality of the above-described ink jet heads 2 on the lower surface thereof. A sheet guide 124 is provided below the ink cartridge 116 at a distance from the inkjet head 2. This sheet guide 124
The sheet S sent to the inside of the printer 100 through the paper feed port of the front wall 106 is indicated by an arrow 1 on the front wall 106 side.
The paper feed roller 128 that conveys in the 26 direction (conveying direction)
They are arranged in a direction perpendicular to the sheet feeding direction, and are rotatably supported by opposing support walls 104. Further, on the downstream side of the ink cartridge 116 with respect to the sheet feeding direction, a pressing roller 130 for pressing the sheet S against the sheet guide 124 is arranged in a direction orthogonal to the sheet feeding direction.

The paper feed roller 128 has a gear 134 fixed to a shaft 132 and a support wall 10 near the gear 134.
4 is connected to a motor 138 via a gear 136 rotatably supported by the motor 4, and the sheet feed roller 128 rotates based on the rotation of the motor 138 to convey the sheet S in the direction of arrow 126. It is.

At the time of printing by the printer 100 configured as described above, the sheet S sent from the paper feed tray 108 is printed.
Is fed into the printer 100 through the paper feed port of the front wall 106. Next, the sheet S is conveyed in the direction of arrow 126 along the sheet guide 124 by the sheet feeding roller 128 that rotates based on the driving of the motor 138. Further, the sheet S moving on the sheet guide 124 is pressed against the sheet guide 124 by the pressing roller 130,
Thereby, the interval between the sheet S and the inkjet head 2 is kept constant.

In synchronization with the movement of the sheet S, the ink cartridge 116 reciprocates along the guide rails 112 and 114 by the rotation of the belt 122, and
The ink is ejected from the inkjet head 2 to the portion of the sheet S that moves on the print 24 and printing is performed. The printed sheet S is discharged onto a discharge tray (not shown).

[0035]

According to the ink jet head of the present invention, the shape memory material in which the shape is stored in a convex shape has an elastic surface which is opposite to the elastic member which is a part of the wall of the ink channel. Since all parts are formed so as to be visible from the opposite side of the member, there is substantially no edge part in the shape memory material. Therefore, when the shape memory material is deformed, the deformation is concentrated on the edge portion, and the problem that the shape memory material causes fatigue is less likely to occur, and the life of the actuator is extended.

According to the actuator forming method of the present invention, the structure of a convex actuator (shape memory material) can be reduced by utilizing a micropyramid obtained by, for example, crystal anisotropic etching of a silicon single crystal wafer. Can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a top view of a channel plate of an inkjet head according to the present invention.

FIG. 2A is a cross-sectional view of the inkjet head according to the present invention in a normal temperature state. (B) Sectional view of the inkjet head according to the present invention when the actuator is heated.

FIG. 3 is an exploded perspective view of the inkjet head according to the present invention.

FIG. 4 is a process chart showing a method for forming a first portion of the upper structure.

FIG. 5 is a process chart showing a method for forming a second portion of the upper structure.

FIG. 6 is a process chart showing a method for forming an upper structure.

FIG. 7 is a partial perspective view of a printer incorporating the ink jet head according to the present invention.

[Explanation of symbols]

2: inkjet head, 8: first substrate (partition wall, elastic member), 10: second substrate, 12: third substrate, 1
4: actuator, 16: heater, 20: ink channel, 28: nozzle, 32: slot, 32a: slope of slot.

Claims (6)

[Claims] At least a part of a wall forming a space for accommodating ink is constituted by an elastic member, and a thin-film shape memory material having a convex shape memory is pressed against the elastic member. By deforming the shape memory material, by reproducing the shape stored in the shape memory material, the elastic member is deformed to reduce the volume in the space, thereby pressurizing and discharging the ink. In the ink jet head, the convex shape memory material has an elastic member whose surface opposite to the side facing the elastic member of the convex shape memory material at least in a state in which the stored shape is reproduced. An ink jet head characterized in that all parts are formed to be visible from the opposite side of the ink jet head. 2. The method according to claim 1, wherein the convex shape memory material includes at least a substantially planar first portion that is in contact with the elastic member.
A substantially planar second portion extending from one side of the first portion to a side opposite to the elastic member, wherein an angle formed by the first and second portions is 125 °. The inkjet head according to claim 1, wherein 3. An ink jet printer comprising the ink jet head according to claim 1. 4. A method for forming an actuator for an ink jet head using a shape memory material, comprising:
A slot having a slope having a predetermined inclination angle with respect to the thickness direction and penetrating the substrate is formed in the planar first substrate having a predetermined thickness, and as a result, the slot is viewed from the substrate surface side. (B) providing a second substrate on the back surface of the first substrate at least in a region where the slot is formed, with respect to the first substrate; A) forming a thin film-shaped shape memory material on a second substrate portion provided on the back surface of the first substrate in the region where the slope is formed and the slot is formed;
Removing the substrate from the first substrate, and (e) removing a predetermined thickness from the back surface of the first substrate at least in the vicinity of the region where the slot is formed, thereby forming a part of the shape memory material. Exposing to the back side of the first substrate. 5. The method according to claim 4, wherein a silicon wafer is used as said first substrate, and said slope is a {111} plane of silicon. 6. A method for forming an actuator for an ink jet head using a shape memory material, comprising:
Forming a slot in a planar substrate having a predetermined thickness so that all of the interface of the slot is visible when the slot is viewed from the substrate surface side;
(B) a step of depositing a thin film of a shape memory material on the boundary surface of the slot; and (c) removing at least the vicinity of the region where the slot is formed by a predetermined thickness from the back surface of the substrate. Exposing a portion of the shape memory material to the backside of the substrate.