JPH03202351A - Ink jet printer head - Google Patents

Abstract

PURPOSE:To realize an simply constituted ink jet printer head which can heat/ cool shape memory alloys in a short time and quickly make a printing by providing a pressure mechanism having shape memory alloys and a Peltier element. CONSTITUTION:A fluid passageway 1a has an ink inlet member 1b, a common passageway 1c, a narrow passageway 1d and branched passageways each of which comprises an operation concavity 1e to operate shape memory alloys, a leading passageway 1f and a nozzle 1g. Reversible shape memory alloys 3 are adhered to an upper surface of a cap plate 2 facing to the operation concavity 1e, and a Peltier element 4 is adhered to he upper surface of the shape memory alloys 3. A Peltier element is an element having an effect of causing heat evolution differently from the joule heat at a contact portion of different conductors or semiconductors when electric current flows through the portion, namely, Peltier effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet printer head that ejects fluid by driving a pressing mechanism attached to a fluid flow path.

[Prior Art] Conventionally, many inkjet printer heads that eject fluid by driving a pressing mechanism attached to a fluid flow path use piezoelectric elements in the pressing mechanism.

However, since the piezoelectric element has a small amount of displacement and a small amount of ink ejected, the printing becomes thin, and since the piezoelectric element is made of ceramic, it is easily damaged and has a short lifespan.

Therefore, Japanese Patent Laid-Open No. 63-57251 discloses an invention using a drive plate made of a shape memory alloy and heating means such as a heater. That is, a drive plate made of a shape memory alloy is subjected to shape memory treatment such that, for example, at room temperature it is deformed into a downwardly bent shape, and when heated to a temperature above room temperature, the bending deformation disappears and it returns to a flat state. . Then, the driving plate is heated by the heating means in accordance with the printing signal, and then the heating is interrupted and the process is repeatedly cooled by the surrounding environmental temperature and contact with the ink, thereby vibrating the driving plate and causing the ink to be ejected. It is used for printing.

Note that as a cooling means for the drive plate, means for blowing air, low-temperature air, or the like is also disclosed.

[Problem to be Solved] However, since cooling is performed by contact with the surrounding environment temperature and ink or by spraying air or low-temperature air, there is a problem that instantaneous cooling is not possible. Therefore, it was not possible to rapidly perform the operation of ejecting ink by sequentially heating and cooling in response to print signals and vibrating the drive plate up and down.

Further, when using means for blowing air or low-temperature air, heating means and cooling means must be provided separately, resulting in a problem that the apparatus configuration becomes complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an inkjet printer head that can instantaneously heat and cool a shape memory alloy, can print quickly, and has a simple device configuration. It is in.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an inkjet printer head that drives a pressing mechanism attached to a fluid flow path to eject fluid, in which the pressing mechanism is reversible. It is composed of a shape memory alloy and a Vertier element that heats and cools the shape memory alloy.

[Function] By switching the direction of current flowing through the Beltier element between forward and reverse, both heating and cooling can be performed instantaneously.

This changes the shape of the shape memory alloy, drives the pressing mechanism, and discharges fluid to perform printing.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

As shown in FIG. 1, the substrate 1 has a fluid flow path 1a formed therein. The fluid flow path 1a is provided with an ink inlet portion 1b and a common flow path 1c, from which the flow path is divided into multiple flow paths (not shown), and each branched flow path passes through a narrow path portion 1d, and the shape memory alloy is activated. It is composed of an actuation recess 1e, a guide path 1f, and a nozzle 1g.

A cover plate 2 is fixed to the upper surface of the substrate 1. A reversible shape memory alloy 3 is fixed to the upper surface of the cover plate 2 facing the operating recess 1e. In this example, the shape memory alloy 3 is a mixture of nickel and titanium in a ratio of 1:1, and is heat treated to an austenite transformation temperature of 50°C and a martensitic transformation temperature of 40°C, so that the shape memory alloy 3 becomes arched downward during austenite transformation. The curved shape (as shown in the third diagram) is memorized so that it becomes a flat plate shape through martensitic transformation.

A Vertier element 4 is adhered to the upper surface of the shape memory alloy 3. Here, the Pertsch element is an element that causes the so-called Beltier effect, which is an effect in which heat is generated or absorbed in addition to Joule heat at the contact when a current is passed through the contact between different types of conductors or semiconductors.

In this embodiment, as the Bertier element 4, Bi
N-type semiconductor 2 consisting of (TeSe)
2.85 0.15 layer and P type 1 consisting of (Bi Sb ) Te3
．． 4 0.8 Semiconductor layers are alternately stacked with insulating layers interposed in between, and the end faces of adjacent semiconductor layers are electrically connected by a conductor, so that the end face of the semiconductor located at one end is connected to the end face of the semiconductor located at the other end. We used semiconductors connected in series up to the end faces.

Therefore, in the illustrated state, both end surfaces of each semiconductor layer are aligned and positioned on both the upper and lower surfaces of the Beltier element 4, and the lower surface of the Beltier element 4 (the lower end surface of each semiconductor layer) is bonded to the shape memory alloy 3. has been done. Heat generation and heat absorption at the lower end surface of the semiconductor layer are transmitted to the shape memory alloy 3.

Lead lines 6a and 6b are connected to the end faces of each semiconductor layer located at both ends of the Beltier element 4, respectively, and a drive signal is supplied from a drive circuit 7. Heat generation in the Bertier element 4 occurs at the junction where current flows from the P-type semiconductor layer to the N-type semiconductor layer, and heat absorption occurs at the junction where the current flows from the N-type semiconductor layer to the P-type semiconductor layer. Therefore, whether the lower surface of the Beltier element 4 is heated or cooled can be determined by reversing the directions of the drive signals supplied to the lead lines 6a and 6b. In this embodiment, when the lead wires 6a are + and 6b are - and a current is applied, the lower surface of the Beltier element 4 generates heat and the shape memory alloy 3 is heated to about 70°C, and the lead wires 6b are + and 6a. -
The applied voltage, current value, energization time, etc. are set so that when a current is applied, the lower surface of the Bertier element 4 absorbs heat and the shape memory alloy 3 is cooled to 20 to 10°C.

The ink flow path 1a is filled with ink 5.

Next, the operation of this inkjet printer head will be explained.

As shown in FIG. 1, when no current is flowing through the lead wires 6a and 6b, the shape memory alloy 3 is at room temperature (assumed to be 20°C), and the martensitic transformation temperature is 40°C, so the shape The memory alloy 3 is in a martensite state and is in a flat plate state as shown in the figure, and therefore the cover plate 2 is also in a flat plate state.

Next, as shown in the second diagram, when the drive circuit 7 (first diagram) applies a positive potential to the lead line 6a and a negative potential to the lead line 6b, a P-type semiconductor layer is applied on the bottom surface of the Bertier element 4. A current flows from the N-type semiconductor layer toward the N-type semiconductor layer and generates heat, which heats the shape memory alloy 3 to 70° C. and causes the austenite transformation salinity to exceed 50° C., so that the shape memory alloy 3 curves downward in an arched manner.

Therefore, the lid plate 2 to which the shape memory alloy 3 is fixed also curves downward in the vicinity of the actuation recess 1e. Then ink 5
is pressed and is not pushed back backward by the narrow passage portion 1d, so the ink is pushed forward and ejected from the nozzle 1g.

Next, as shown in FIG. 3, when the drive circuit 7 applies a negative potential to the lead line 6a and a positive potential to the lead line 6b, the N-type semiconductor layer changes from the P-type semiconductor layer to the bottom surface of the Bertier element 4. A current flows toward the shape memory alloy 3, which absorbs heat, and thus the shape memory alloy 3 is cooled to 20 to 10°C, and the martensitic transformation temperature becomes 40°C or less, so that it returns to a flat plate state.

Next, when the current is stopped, the shape memory alloy 3 becomes a base state, and the cover plate 2 maintains a flat state as shown in the first diagram.

By repeating the above operations according to the drive signal, recording with ink is performed on the recording paper.

[Effects] Since the inkjet printer head of the present invention has a pressing mechanism made of a shape memory alloy and a Beltier element, heating and cooling can be performed instantaneously to improve response characteristics, and printing can be performed quickly.

In addition, the current applied to the Beltier element is switched between forward and reverse to switch between heat generation and heat absorption, and this is transmitted to the shape memory alloy.
It is possible to heat and cool a shape memory alloy with an extremely simple configuration.

[Brief explanation of drawings]

Figure 1 is a sectional view showing one embodiment of the present invention, Figures 2 and 3 are
The figure is a sectional view explaining the operation. 1a... Fluid flow path, 3. - Shape memory alloy, 4. - Vertier element, 5. - Fluid. Above Figure 1 0 Figure 2 3s

Claims (1)

[Claims] In an inkjet printer head that drives a pressing mechanism attached to a fluid flow path to eject fluid, the pressing mechanism includes a reversible shape memory alloy and a Peltier that heats and cools the shape memory alloy. An inkjet printer head comprising an element.