JP2000272121A - Ink jet head and ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a great volume change by deforming a second wall part on the basis of the deformation of a first wall part having a part formed of a shape memory material. SOLUTION: A shape memory substrate 20 is formed of a plate having a thickness of approximately 1-several μm of an optional shape alloy, e.g. TiNi alloy. The substrate 20 is bonded to another face of a channel plate 8 at a martensite phase (ordinary temperature) not higher than a transformation point. At this time, the substrate is extended to apply an initial distortion in a direction orthogonal to a longitudinal direction of ink channels 10. A predetermined voltage (pulse voltage) is impressed to an electrode corresponding to the selected ink channel 10, whereby a corresponding deformation wall 32 heats. When the deformation wall 32 reaches the transformation point, the substrate is transformed from the martensite phase to a mother phase (high temperature) and is deformed to a state before the initial distortion is applied. As a result of this, walls 12 at the side of ink channels are bent inside and the ink of the corresponding ink channel 10 is pressured and discharged from a nozzle.

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 more particularly to an ink jet head used for an ink jet printer for forming an image by flying ink.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 6-91865 discloses an ink jet head using a shape memory alloy. In this inkjet head, as shown in FIGS. 7 and 8, a plurality of grooves (that is, ink chambers 51) are formed by processing the surface of the substrate. The ink chamber 51 is located in the first
The first regulating layer 53 is covered with a regulating plate 54 composed of a regulating layer 53 and a second regulating layer 52 fixed on the first regulating layer 53. Here, the second restriction layer 52 is formed of a shape memory alloy. Also, the second regulating layer 5 made of a shape memory alloy
2 is curved toward the outside of the ink chamber 51 in a normal temperature state (martensite phase).

In an ink-jet head employing such a configuration, when a voltage is applied to the regulating plate 54 and heated, the second regulating layer 52 made of a shape memory alloy is transformed from a martensite phase to a parent phase, As shown by a dotted line in FIG. 5, the state changes from a curved state to a flat state. As a result, the ink contained in the ink chamber 51 flies through the nozzle 57 formed on the substrate.

[0004]

However, this ink jet head has the following problems. As described above, the second restriction layer 52 made of a shape memory alloy takes a curved shape at normal temperature (martensite phase) and has a flat shape at high temperature (mother phase). However, in practice, it is not easy to memorize such a transformation in a shape memory alloy. The shape memory alloy can obtain a larger deformation amount than the piezoelectric element. For example, the deformation amount of the piezoelectric element is about 0.1 to
In contrast to 0.2%, the deformation amount of the shape memory alloy reaches a maximum of about 5%. However, the second made of shape memory alloy
In the regulation layer #, the periphery thereof is fixed to the substrate and the deformation thereof is regulated, so that the potential deformability of the shape memory alloy cannot be effectively utilized. The change in volume due to the deformation of the shape memory alloy is limited to the deformation volume of the shape memory alloy, and the change in volume required for ink ejection may not be obtained in some cases.

Therefore, the present invention relates to an ink jet head using a shape memory alloy, in which the shape memory of the shape memory alloy is easy, the deformability of the shape memory alloy can be sufficiently exhibited, and a large volume change is caused by the deformation of the shape memory alloy. It is an object of the present invention to provide an ink jet head capable of obtaining the following.

[0006]

In order to achieve these objects, in an ink jet head according to the present invention, at least a part of a space for containing ink has a first wall portion and the first wall portion.
And a second wall portion adjacent to the second wall portion.
Here, the first wall portion has a portion made of a shape memory material. The second wall portion is deformed based on the deformation of the portion made of the shape memory alloy, thereby reducing the volume in the space.

An ink jet head according to another embodiment of the present invention and an ink jet recording apparatus provided with the ink jet head have a nozzle for connecting the space with the atmosphere. Accordingly, the ink is pressurized due to the decrease in the volume in the space, and the ink is discharged to the atmosphere through the nozzle.

[0008]

According to the ink jet head and the ink jet recording apparatus configured as described above, when the first wall portion having the portion made of the shape memory alloy is deformed,
With the deformation, the second wall portion is deformed. Therefore,
It provides more volume change to the space than if the first wall portion were simply deformed, thereby allowing the ink to be more strongly pressurized. In addition, a configuration of an ink jet head that can sufficiently exhibit the deformability of the first wall made of the shape memory material is possible. Therefore, the ink can be strongly pressurized by the deformation of the shape memory material and can be reliably ejected.

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 4,
The inkjet head 2 according to the present invention generally includes three members—a channel plate 8, a nozzle plate 4, and a shape memory substrate 20—. The channel plate 8 is formed of a plate having a predetermined thickness, and has elongated separation slots 14 formed in parallel at predetermined intervals.
In the channel plate 8, another slot (ink channel 10) is formed between the separation slot 14 and the adjacent separation slot 14 in parallel with and along the separation slot 14. Thereby, a pair of longitudinally extending thin side walls 12 forming the ink channel 10 are formed corresponding to each ink channel 10. In this embodiment, three ink channels 1 are provided in one channel plate.
Although only 0 is formed, more (for example, several hundred) ink channels 10 may be formed. At a predetermined interval from one end in the longitudinal direction of these ink channels 10, a common ink chamber 18 is provided in the channel plate 8.
Is formed. In order to connect each ink channel 10 to the common ink chamber 18, a groove (ink inlet 16) corresponding to each ink channel 10 is formed on one surface of the channel plate 8.

The ink jet head 2 is preferably made of a material having high rigidity. For example, a plate made of metal such as stainless steel, silicon, glass, ceramics or the like can be used. The separation slot 14, the ink channel 10, and the ink inlet 16 are preferably formed such that the ink inlet 16 is formed first, and then the separation slot 14, the ink channel 10 is formed by etching or the like. In order to form a high-density (high-resolution) inkjet head 2 by narrowing the interval between adjacent ink channels 10 and to form a side wall having a high aspect ratio (width / height), for example, a silicon substrate is used. It is preferable to form a separation slot or the like by anisotropic etching. In this case, the etching is performed in two stages, one of which forms the separation slot 14 and the ink channel 10 and the other of which forms the ink inlet 1.
6 is formed. However, the processing of the inkjet head 2 is not limited to etching, and for example, sand blasting, dicing, RIE (reactive ion etching), or the like may be used. Inkjet head 2
When forming with a photosensitive glass, besides these methods,
Photolithography can also be used.

The nozzle plate 4 is provided with the ink inlet 1
A first plate portion 26 having a size and shape covering one surface of the channel plate 10 in which the channel plate 6 is formed, and a second plate portion 28 extending downward from one edge of the first plate portion 26. First plate part 2
6, each ink channel 10 is spaced at the same interval as the ink channels 10 formed on the channel plate 8, and on one or a plurality of lines in a direction substantially orthogonal to the longitudinal direction of the ink channels 10. The nozzles 6 are formed one by one correspondingly. The nozzle plate 4 has a first plate portion 26 on one surface of the channel plate 8 with each nozzle 6 facing the corresponding ink channel 10, as best shown in FIGS. With the second plate portion 28 placed on one end side of the channel plate 8 (see FIG. 2), the second plate portion 28 is adhered to the channel plate 8 by, for example, an adhesive.

The nozzle plate 4 may be made of any of metals such as stainless steel, silicon, glass, and ceramics, similarly to the channel plate 8 described above.
The nozzle 6 is formed by an appropriate method such as etching, sandblasting, or photolithography depending on the material.

The shape memory substrate 20 is an extremely thin plate having a thickness of about 1 to several micrometers, and is made of any shape memory alloy, for example,
TiNi alloy, alloy obtained by adding Pd or Cu to TiNi,
It is made of Cu-Zn-Al alloy. The SMA substrate 20 does not need to be formed of metal, and may be formed of a material other than metal, such as a shape memory resin, a shape memory fiber, or a composite material thereof. Note that TiNi alloys have different characteristics (especially transformation temperature) depending on the composition.
A composition ratio of 50% to 50% and a transformation temperature of 70 ° C. can be suitably used. In the case of the TiNi alloy having this composition, the maximum strain is about 5% and the generated stress is about 600 MPa.

As shown in FIGS. 2, 3 and 4, the shape memory substrate 20 has a martensite phase (normal temperature) lower than the transformation temperature.
Then, it is bonded to the other surface of the channel plate 8 by an appropriate means (for example, an adhesive). At this time, as shown in FIG. 5A, the shape memory substrate 20 is
Are stretched in a direction orthogonal to the longitudinal direction of the first direction, thereby giving an initial strain. Next, a plurality of slots are formed in the shape memory substrate 20 along the separation slots 14 by dicing (FIG. 5B), and walls (deformed walls 32) corresponding to the respective ink channels 10 are formed (FIG. 5 (B)). C)). Also,
As shown in FIG. 3, electrodes 30 are provided at both ends of a deformed wall 32 corresponding to both ends of the ink channel 10, and these electrodes 30 are connected to a drive circuit 34.

In the ink jet head 2 configured as described above, the ink 36 is supplied to the common ink chamber 18.
The ink 36 is further supplied to and filled in the corresponding ink channel 10 via each ink inlet 16. From this state, the selected ink channel 1
When a predetermined voltage (pulse voltage) is applied from the drive circuit 34 to the pair of electrodes 30 corresponding to 0, the corresponding deformed wall 3
2 acts as a resistor and generates heat. And the deformed wall 32
When the temperature reaches the transformation temperature, the deformed wall 32 transforms from the martensite phase to the parent phase, and as shown in FIG. 5D, deforms to a state before the initial strain is applied. As a result, the ink channel side wall 12 fixed to the longitudinal end of the deformed wall 32 bends inward, and the ink 36 of the corresponding ink channel 10 is pressurized, whereby the ink 36 is discharged from the corresponding nozzle 6. Discharge. Next, when the voltage application by the drive circuit 34 ends, the heat generation of the deformed wall 32 ends, and the deformed wall 32 is brought to a normal temperature state. as a result,
The deformed wall 32 transforms from the parent phase to the martensite phase, and returns to the initial state with the initial strain (the state shown in FIG. 5C). At this time, a negative pressure is generated in the ink channel 10, and the ink 36 is replenished from the common ink chamber 18 through the ink inlet 16 by the suction force.

As described above, according to the ink jet head 2 of the present invention, not only the deformed wall 32 forming the ink channel 10 is deformed but also the side walls 12 disposed on both sides thereof. Moreover, since the entire side wall 12 is deformed toward the inside of the ink channel 10, the volume change of the ink channel 10 is very large. That is, the deformation of the deformable wall 32 made of the shape memory alloy can be sufficiently utilized for the change in the volume of the ink channel 10, so that the ink 36 in an amount necessary for image formation can be reliably discharged.

In the above embodiment, a voltage is applied to the deformed wall 32 and the transformation from the martensite phase to the parent phase is caused by the Joule heat generated by the deformed wall 32 itself.
A configuration in which heat is directly applied to the transformation wall 32 by a heater may be used. In order to return the heated deformed wall 32 to the initial state as quickly as possible, a mechanism for cooling the deformed wall 32 (either an air cooling mechanism or a water cooling mechanism may be provided). When the temperature of the deformed wall 32 is increased, the deformed wall 3
2, if a current-carrying wiring or a heater is appropriately provided on the deformed wall 32 so that the temperature of the portion other than the joint portion with the ink channel side wall 12 mainly rises, the joint portion between the deformed wall 32 and the ink channel side wall 12 is formed. And a change in stress applied to the ink jet head 2 can be reduced, and as a result, physical deterioration of the entire inkjet head 2 can be delayed.

FIG. 6 shows the ink channel section 10 of the present invention.
3 shows another embodiment of the present invention. Each is a cross-sectional view near the center of the ink channel 10 in the longitudinal direction and perpendicular to the longitudinal direction. 6 (A), 6 (B) and 6 (C), the column 38 on the right side of the channel 10 does not move and does not bend even if the shape of the deformed wall 32 changes. That is, if a sufficient change in volume can be obtained in the ink channel 10, only one ink channel side wall 12 may be bent. Also, as shown in FIG.
2. The support 38 may have a curved surface.

There are many methods for setting the initial strain of the shape memory substrate 20 in the martensite phase. For example, when the shape memory substrate 20 and the ink channel side wall 12 are joined together by applying heat to the entirety, and the temperature is lowered to about the temperature in an environment where the inkjet head 2 normally operates, the initial strain is set. State. This utilizes the difference in the coefficient of thermal expansion between the material of the shape memory substrate 20 and the material of the ink channel side wall 12. Further, the entire channel plate 8 is compressed in a direction perpendicular to the plurality of ink channel side walls 12 arranged in a row, and the shape memory substrate 20 is compressed.
The initial strain is also set by the procedure of joining the shape memory substrates 20 or the procedure of joining the shape memory substrate 20 after bending the ink channel side wall 12 by some external force in advance.

FIG. 9 shows a part of a printer 100 incorporating the ink jet head 2. 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.
An ink cartridge 11116 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 10 on its lower surface. Ink cartridge 116
A sheet guide 124 is provided below and at a distance from the inkjet head 10. This seat guide 1
24, a sheet feeding roller 128 for conveying the sheet S fed into the printer 100 through the sheet feeding port of the front wall 106 in the direction of arrow 126 (conveying direction).
Are arranged in a direction perpendicular to the paper feeding direction, and are rotatably supported by the opposing support wall 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 ink head 10 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 ink jet head 10 to the portion of the sheet S that moves on the top 24 and printing is performed. The printed sheet S is discharged onto a discharge tray (not shown).

(Demonstration by FEM analysis) An ink jet head was provided with the following conditions, and it was determined whether or not the ink jet head could withstand practical use by FEM (Finite E).
element method (finite element method) analysis. (1) Experimental conditions-Composition ratio of TiNi alloy: 50% -50% (transformation temperature, maximum strain, generated stress of TiNi alloy: 70 ° C, 5%, 60%
0 MPa)-Ink channel width: 50 µm-Ink channel length: 200 µm-Ink channel side wall width: 10 µm-Ink channel side wall height: 100 µm-Deformed wall thickness: 1 µm (2) Items to be checked For ordinary inkjet heads For example, using a general water-based ink, a diameter of several tens μ
When forming a dot of m, the deformation volume of the ink channel portion of about 20 picoliters (20 × 10 ⁻¹⁵ m ³ ) is required. is there. These values are calculated from techniques known to those skilled in the art. (3) Analysis result The deformation volume of the ink channel portion was 20 picoliters,
It was confirmed that the pressure for pressing the ink was 1.8 MPa. Therefore, it can be understood that the ink jet head is effective.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view (and a partial perspective view) of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a side view of the inkjet head of FIG.

FIG. 3 is a perspective view showing a cross section of the inkjet head of FIG. 1;

FIG. 4 is a sectional view of the inkjet head of FIG. 1;

FIG. 5 shows the formation and operation of an ink channel, FIG.
FIG. 3 is a schematic view of a part of the inkjet head of FIG.

FIG. 6 is a cross-sectional view of an ink channel portion in an inkjet head according to some preferred embodiments of the present invention.

FIG. 7 is a sectional view of a conventional inkjet head.

FIG. 8 is a plan view of a conventional inkjet head.

FIG. 9 is a partial perspective view of a printer incorporating the ink jet head according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 4 ... Nozzle plate 6 ... Nozzle 8 ... Channel plate 10 ... Ink channel 14 ... Separation slot 16 ... Ink inlet 18 ... Common ink chamber 20 ... Shape memory substrate 32 ... Deformed wall 36 ... Ink

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhisa Ishida 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. (reference) 2C057 AF51 AG12 AG43 BA04 BA15

Claims (3)

[Claims] At least a part of a space for accommodating ink is formed by a first wall portion and a second wall portion adjacent to the first wall portion, wherein the first wall portion is a shape memory. An ink jet head having a portion made of a material, wherein the second wall portion is deformed based on the deformation of the portion made of the shape memory material, thereby reducing the volume in the space. . 2. The ink jet printer according to claim 1, further comprising a nozzle for connecting the space to the atmosphere, wherein the ink is pressurized by reducing the volume in the space, thereby discharging the ink to the atmosphere via the nozzle. The ink jet head according to claim 1, wherein 3. An ink jet recording apparatus comprising the ink jet head according to claim 2.