JP2000309092A - Ink-jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the thermal response property of the shape memory material in an ink-jet recording head using a shape memory material. SOLUTION: An ink-jet recording head comprises a shape memory material layer 25 providing a part of the wall part of an ink channel 39, a heating means 29 for heating the shape memory material layer 25, and a nozzle 51 communicating with the ink channel 39. The ink-jet recording head further comprises a heat blocking layer 31 formed so as to cover the shape memory material layer 25 and the heating means 29, and a radiating layer 35 formed in the heat blocking layer 31 on the opposite side with respect to the shape memory material layer 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for discharging ink droplets to a recording medium by pressing ink in an ink channel by utilizing deformation of a shape memory material.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording head using a shape memory material has been proposed. For example, JP-A-6-91865 describes an ink jet recording head shown in FIGS. 7A and 7B. In this ink jet recording head, the upper opening of each ink channel 1 in the drawing is closed by a bias spring layer 2 having an elastic restoring force which tends to bulge upward. A shape memory alloy layer 3 is formed on 2. In FIG. 7, reference numeral 4 denotes a nozzle, and 5 denotes a drive circuit for generating a resistance heat by energizing the shape memory alloy layer 3.

At room temperature, the shape memory alloy layer 3, which is a martensite phase, is bent in a state of bulging upward in the figure due to the elastic restoring force of the bias spring layer 2. When the temperature of the shape memory alloy layer 3 rises to the transformation temperature or higher due to energization from the drive circuit 5, the shape memory alloy layer 3 which has become the austenitic phase is shown by a dotted line in the drawing against the urging force of the bias spring layer 2. Deforms into a flat plate as shown. As a result, the volume of the ink channel 1 is reduced, the ink is pressurized, and the ink droplet is ejected from the nozzle 4.

[0004]

In an ink jet recording head using a shape memory material as described above, ink droplets are ejected by repeating heating and cooling of the shape memory material. To achieve this, the thermal response is good, that is, the temperature of the shape memory material quickly rises to the transformation temperature during heating, while the temperature of the shape memory material rapidly falls to a temperature below the transformation temperature during cooling. It is necessary.

However, with a structure in which the shape memory material layer 3 is simply provided on the bias spring layer 2 as in the conventional ink jet recording head shown in FIG. 7, good thermal responsiveness cannot be obtained. It can be driven only at a drive frequency of about 10 Hz to several tens of Hz.

Accordingly, it is an object of the present invention to improve the thermal response of a shape memory material in an ink jet recording head using the shape memory material.

[0007]

In order to solve the above-mentioned problems, the present invention provides a shape memory material layer constituting a part of a wall portion of an ink channel, a heating means for heating the shape memory material layer, In an ink jet recording head including a nozzle communicating with an ink channel, a heat blocking layer formed so as to cover the shape memory material layer together with a heating unit, and a heat blocking layer formed on a side of the heat blocking layer opposite to the shape memory material layer. And a heat radiation layer.

In the ink jet recording head of the present invention,
As described above, since the heat blocking layer that covers the shape memory material layer together with the heating means is provided, the loss of heat generated by the heating means is reduced, the shape memory material layer is efficiently heated, and quickly reaches the transformation temperature. Raise the temperature. Further, since the heat radiation layer is provided on the side of the heat insulation layer opposite to the shape memory material layer, when the heating by the heating means is stopped, the temperature of the shape memory material layer quickly drops to below the transformation temperature. Thus, in the ink jet recording head of the present invention, since the thermal response of the shape memory material layer is good, it is possible to perform driving at a high frequency by setting a short driving cycle of heating and cooling.

In the case where the heat radiating layer is formed of a metal plate and the heating means is formed of a heating resistor formed on the shape memory material layer, a deformation absorbing layer is provided between the heat insulating layer and the heat radiating layer. It is preferable to interpose. By providing the deformation absorption layer, even if the heat insulation layer is repeatedly deformed together with the shape memory material layer, the heat insulation layer and the heat sink are always in close contact with the deformation absorption layer. The heat is efficiently transmitted to the heat radiating plate through the heat sink.

The thermal barrier layer is not particularly limited as long as it has a low thermal conductivity.
osition), sputtering, vapor deposition, SiO ₂ was formed by screen printing or the like, polyimide is particularly preferred. The heat radiation layer is not particularly limited as long as it is a material having high thermal conductivity. For example, an Al plate, a SUS plate, a Ni plate, a C
A metal plate such as a u plate or a Ti plate is suitable. The deformation absorbing layer is preferably made of a material having good deformation followability, such as a conductive rubber sheet, a silicone compound, silicone rubber, and silicone oil.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention shown in the drawings will be described in detail.

FIG. 1 shows an ink jet recording apparatus 11 having an ink jet recording head 10 according to an embodiment of the present invention.

The ink jet recording apparatus 11 includes a moving mechanism 13 for moving a carriage 12 in a main scanning direction indicated by arrows X1 and X2, and a feeding mechanism for moving a recording paper 14 as a recording medium in a sub-scanning direction indicated by arrow y. 15 is provided.

In the carriage 12, an ink jet recording head 10 for ejecting ink droplets onto the recording paper 14, and a cartridge type ink tank (not shown) for storing ink to be supplied to the ink jet recording head 10 are housed. ing.

As shown in FIGS. 2 to 4, the ink jet recording head 10 includes a flow path substrate 21 and a bias spring layer 2.
3. Shape memory material layer 25, insulating layer 27, heating resistor 2
9, a heat shielding layer 31, a deformation absorbing layer 33, a heat radiating plate 35, and a nozzle plate 37.

The flow path substrate 21 is made of Si having a thickness of 300 μm.
A plurality of ink channels 39 made of a (silicon) plate body and having upper and lower sides open in the figure are provided in parallel with each other. A supply chamber 41 having upper and lower sides open at one end in the longitudinal direction of the ink channels 39 is provided. Each ink channel 39 and the supply chamber 41 communicate with each other through an inlet 43. The supply chamber 41 communicates with the ink tank (not shown). The thickness of the flow path substrate 21 is set in a range of about 100 μm to 650 μm.

A bias spring layer 23 made of a thermally oxidized SiO ₂ thin film having a thickness of 10 μm is provided on the entire surface of one surface 21 a (the upper surface side in the figure) of the flow path substrate 21. The upper openings of the channel 39 and the supply chamber 41 are closed. The bias spring layer 23 has an elastic restoring force that tends to elastically deform in the direction in which the volume of the ink channel 23 increases, that is, in the direction in which the upper side swells in the drawing. In addition,
The thickness of the bias spring layer 23 is set in a range of about 1 μm to 50 μm.

In the drawing of the bias spring layer 23, a thickness 1 of TiNi (titanium nickel) alloy
A 5 μm shape memory material layer 25 is provided. Also,
On the entire upper surface of the shape memory material layer 25, an insulating layer 27 made of SiO ₂ and having good thermal conductivity is provided.
Further, a heating resistor 29 made of TaN (tantalum nitride) and having a thickness of 5 μm is provided on the insulating layer 27 at a position corresponding to each ink channel 39. One end of each heating resistor 29 is connected to the drive circuit 46 via the individual electrode 45, and the other end is grounded via the common electrode 47. The thickness of the bias spring layer 23 is 1 μm.
The heating resistor 29 is set in the range of about 50 μm.
Is 0.01 μm to 50 μm depending on the material, the manufacturing method and the like.
It is set in a range of about μm.

In order to heat the shape memory material layer 25 by the heat generated by the heat-generating resistor 29, the heat-generating resistor 29 and the insulating layer 27 are coated with SiO ₂ (thermal conductivity 0.5 to 0.5).
1.1 W / m · K) and a heat insulating layer 31 having a good heat insulating property and a thickness of 3 μm are provided. In addition, the thickness of the heat shielding layer 31 is set in a range of about 1 μm to 20 μm.

Further, a 1 mm-thick deformation absorbing layer 33 made of a silicon compound, which is a material that is relatively flexible and has good followability to deformation, is provided on the heat blocking layer 31. On this deformation absorption layer 33, a heat dissipation plate 35 made of an Al plate (constituting a heat dissipation layer in the present invention).
The upper surface of the heat sink 35 is in contact with the outside air in the drawing. The thickness of the deformation absorbing layer 33 is set in a range from several tens of μm to several mm.

On the other hand, a nozzle plate 37 made of a glass plate having a thickness of 50 μm is mounted on the other surface 21 b (the lower surface side in the figure) of the flow path substrate 21, and the ink channel 39 and the supply chamber are formed by the nozzle plate 37. 4
The lower opening 1 is closed. Nozzle plate 37
Are provided with a plurality of nozzles 51 communicating with the corresponding ink channels 39 respectively. In addition, the nozzle plate 37 may be made of Ni, SUS, polyimide, or the like, and the thickness is set in a range of about 10 μm to 100 μm.

A method for manufacturing the above-described ink jet recording head will be described. Note that the vertical directions in FIGS. 5 and 6 are opposite to those in FIGS. 2 to 4. First, FIG.
As shown in FIG. 2A, thin films 53a, 53b of thermally oxidized SiO ₂ are formed on both surfaces 21a, 21b of a flow path substrate 21 made of silicon.
To form One of the thin films 53a forms the insulating layer 23.

Next, as shown in FIG. 5B, a thin film 53a of thermally oxidized SiO ₂ on one side 21a of the flow path substrate 21 is formed.
A thin film of TiNi is formed on the (bias spring layer 23) to form a shape memory material layer 25, and annealing is performed at about 500 ° C. to store the planar shape in the shape memory material layer 25. When cooling after annealing, a compression internal stress is generated in the shape memory material layer 25 and the bias spring layer 23. Then, FIG.
As shown in (C), the entire surface of the shape memory material layer 25 is S
An insulating layer 27 made of iO ₂ is formed.
As shown in (D), the heating resistor 29 made of TaN, the individual electrode 45 made of Al, and the common electrode 47 are formed on the insulating layer 27 by patterning.

Next, as shown in FIG. 5E, while the etching mask is formed by the thin film 53b on the other surface 21b side of the flow path substrate 21, the heating resistor 29 and the insulating layer 27 are polished with wax 55. cover. Then, as shown in FIG. 5F, the channel substrate 21 is etched to form the ink channel 39 and the supply chamber 41. By forming the ink channel 39, the compressive stress of the bias spring layer 23 is released, and as a result, the bias spring layer 23, the shape memory material layer 25, the insulating layer 27, and the heating resistor 29 increase the volume of the ink channel 39. To swell in the direction of the

Next, as shown in FIG. 6A, the thin film 53b and the wax 55 constituting the etching mask are removed, and as shown in FIG. 6B, a nozzle plate 37 is placed on the surface 21b of the flow path substrate 21. Attach. Further, as shown in FIG. 6 (C), an S layer is formed on the heating resistor 29 and the insulating layer 27.
The thermal barrier layer 31 made of iO ₂ is formed.

On the other hand, a silicon compound deformation absorbing layer 33 is formed on the entire surface of one side of the heat radiating plate 35 made of an Al plate by screen printing, and as shown in FIG. Of the heat absorbing layer 3
Attach to 1.

The operation of the ink jet recording head 10 will be described. In a normal temperature state in which the power supply to the heating resistor 29 is stopped, the elastic restoring force of the bias spring layer 23 causes the shape memory material having a martensite phase. The portion constituting the upper wall of the ink channel 39 of the layer 18 has a shape which bulges upward as shown in FIG.

When the heating resistor 29 is energized by the drive circuit 46 to generate heat, the heat is transmitted to the shape memory material layer 25 via the insulating layer 27. Then, the shape memory material layer 2
When the temperature of No. 5 rises to the transformation temperature or higher, the shape memory material layer 25 in the austenite phase has a planar shape against the restoring force of the bias spring layer 23 as shown by a dashed line in FIG. As a result, ink channel 3
9 is reduced, and the pressurized ink is ejected from the nozzle 51.

Since the heating resistor 29 is surrounded by the heat blocking layer 31 and the insulating layer 27, the driving circuit 46
When the heating resistor 29 starts to generate heat due to energization from
Most of the generated heat is not on the side of the heat-blocking layer 31 having a low thermal conductivity, but rather through the insulating layer 27 first.
Is transmitted to That is, since the heat blocking layer 31 is provided, the heat loss generated by the heating resistor 29 at the start of energization is small, and the shape memory material layer 25 is efficiently heated. As a result, when the energization of the heating resistor 29 is started, the shape memory material layer 25 quickly rises to the transformation temperature and shifts from the martensite phase to the austenite phase.

The energization of the heating resistor 29 is stopped,
When the shape memory material layer 25 is cooled to a temperature lower than the transformation temperature and returns to the martensite phase, the portion of the shape memory material layer 25 that forms the upper wall of the ink channel 23 is moved upward by the restoring force of the bias spring layer 23. It returns to the bulged shape. As a result, the volume of the ink channel 39 increases, and ink is supplied from the supply chamber 41 to the ink channel 39 via the inlet 43.

If only the above-mentioned heat-blocking layer 31 is provided, even if the heat generation of the heating resistor 29 is stopped, the heat-blocking layer 31 is not used.
As a result, heat is accumulated in the shape memory material layer 25, and the temperature of the shape memory material layer 25 does not decrease quickly. However, since the heat shielding layer 31 is provided with the heat radiating plate 35 cooled by the outside air via the deformation absorbing layer 33, the heat generating resistor 2
During the energization of 9, the heat transmitted to the heat blocking layer 31 instead of the shape memory material layer 25 side is transmitted to the heat radiating plate 35 via the deformation absorbing layer 33 and is discharged to the outside air. Also, the heating resistor 29
Stops generating heat, the heat of the shape memory material layer 25 is transmitted to the heat radiating plate 35 via the insulating layer 27, the heat blocking layer 31, and the deformation absorbing layer 33, and is released to the outside air. In particular, the thermal barrier layer 3
Since the deformation absorption layer 33 is provided between the heat dissipation plate 35 and the heat radiation plate 35 which is a rigid body,
And the heat shield layer 31 and the heat sink 3
5 is always in close contact with the deformation absorbing layer 33, and at this point, the heat radiation
Good heat conduction to

For the above reasons, when the heat generating resistor 29 stops generating heat, the shape memory material layer 25 quickly drops to a temperature lower than the transformation temperature, and the shape memory material layer 25 quickly changes from the martensite phase to the austenite phase. Transition.

As described above, heating and cooling of the shape memory material layer 25 are repeated and deformed by energizing and de-energizing the heating resistor 29, so that ejection of ink droplets is repeated. By providing the heat blocking layer 31, the temperature of the shape memory material layer 25 quickly rises to the transformation temperature at the time of heating, and the temperature of the shape memory material layer 25 rapidly transforms at the time of cooling by providing the heat sink 35. The temperature drops below the temperature, and the transition between the martensite phase and the austenite phase of the shape memory material layer 25 is performed quickly. As described above, in the ink jet recording head of this embodiment, since the thermal response of the shape memory material layer 25 is good, the heating resistor 29
, The cycle of energization / de-energization with respect to is shortened, and driving at a high frequency of several KHz enables high-speed printing.

The present invention is not limited to the above embodiment, and various modifications are possible. First, in the above embodiment, the radiator plate is air-cooled, but the radiator plate may be configured to be water-cooled, or may be configured to be forcibly cooled using a Peltier element or the like. In these cases, the thermal response of the shape memory material layer is further improved.

Further, the shape memory material layer is made of the TiN
It is not limited to the thin film of the i-alloy, but may be an alloy obtained by adding Pb or Cu to TiNi, or another shape memory alloy such as a Cu-Zn-Al alloy. Further, the shape memory material layer may be made of a shape memory resin and a shape memory fiber. Further, the shape memory material layer may be formed of a composite material including at least one of a shape memory alloy, a shape memory resin, and a shape memory fiber.

Further, if the bias spring layer elastically regulates the shape of the shape memory material layer at normal temperature,
The configuration is not particularly limited. The insulating layer is made of SiO ₂
The material is not limited to this, and may be any insulating material having a high heat transfer coefficient.

Further, the heating resistor is limited to TaN.
Not specified, TaSiO_Two(Tantalum silicon oxide), R
u_TwoO_Five(Ruthenium oxide), NiCr (nichrome), H
fB _Two(Hafnium diboride)_,TaAl (Tantalum A
Other materials such as Rumi) may be used. Also, shape memory material
The means for heating the heating layer should be limited to those that energize the heating resistor.
Not determined, shape memory material layer is divided for each ink channel
Generated by energizing the separated individual shape memory material layers.
The temperature of the shape memory material layer is raised by the applied resistance heat.
May be. In this case, it is necessary to provide an insulating layer
There is no.

The thermal barrier layer is not limited to the above SiO ₂ , but may be a material having low thermal conductivity such as polyimide. The deformation absorbing layer is not limited to the silicone compound, but may be any material having good deformation followability and heat transferability. For example, a conductive rubber sheet, silicone rubber, silicone oil or the like can be used as the deformation absorbing layer. The heat radiating plate may be a metal plate having another high thermal conductivity such as a SUS plate, a Ni plate, a Cu plate, and a Ti plate in addition to the Al plate. The material is not necessarily limited to a metal plate as long as the material has a high thermal conductivity.

In the above embodiment, the shape memory material layer becomes flat when heated, but may be one that protrudes into the ink channel when heated. Further, the shape memory material layer may be flat at normal temperature, and may protrude into the ink channel when heated.

[0040]

As is apparent from the above description, since the ink jet recording head of the present invention is provided with the heat blocking layer covering the shape memory material layer together with the heating means, the loss of heat generated by the heating means is small. As a result, the shape memory material layer is efficiently heated, and quickly rises to the transformation temperature. In addition, since the heat radiation layer is provided on the side opposite to the shape memory material layer with respect to the heat blocking layer, the temperature of the shape memory material layer rapidly drops to below the transformation temperature when the heating by the heating means is stopped. As described above, the ink jet recording head of the present invention can be driven at a high frequency by setting a short cycle of heating and cooling since the shape memory material layer has good thermal responsiveness.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an inkjet recording apparatus including an inkjet recording head according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional perspective view showing an inkjet recording head according to an embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIGS. 5A, 5B, 5C, 5D, 5E, and 5F are cross-sectional views illustrating a method for manufacturing an ink jet recording head.

FIGS. 6A, 6B, 6C, and 6D are cross-sectional views illustrating a method for manufacturing an ink jet recording head.

FIG. 7A is a plan view showing a conventional ink jet recording head, and FIG. 7B is a cross-sectional view taken along line VII-VII of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ink jet recording head 11 Ink jet recording apparatus 21 Flow path substrate 23 Bias spring layer 25 Shape memory material layer 27 Insulating layer 29 Heating resistor 31 Heat blocking layer 33 Deformation absorption layer 35 Heat sink 37 Nozzle plate 39 Ink channel 41 Supply chamber 43 Inlet 45 individual electrode 46 drive circuit 47 common electrode

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Samejima 2-3-1, Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. 2C057 AF03 AF51 AG12 AG43 BA04 BA15

Claims (2)

[Claims] 1. An ink jet recording head comprising: a shape memory material layer constituting a part of a wall portion of an ink channel; heating means for heating the shape memory material layer; and a nozzle communicating with the ink channel. An ink jet recording head, comprising: a heat blocking layer formed so as to cover a storage material layer together with a heating means; and a heat radiation layer formed on a side of the heat blocking layer opposite to the shape memory material layer. 2. The heat radiation layer is made of a metal plate, the heating means is made of a heating resistor formed on the shape memory material layer, and a deformation absorption between the heat insulation layer and the heat radiation layer. 2. The ink jet recording head according to claim 1, wherein a layer is interposed.