JPH0473157A - Ink jet printer head - Google Patents

Abstract

PURPOSE:To make it possible to keep a density of a print type constant even if temperature changes by providing at a nozzle a form memory material for indicating a reversible form memory effect so as to store previously transformation temperature and deformation quantity of the form memory material in conformity with changes of temperature of an ink being used. CONSTITUTION:A TiNi memory alloy 1, which is attached to the back face of a nozzle 2 i.e. to the inside of a head, is treated with reversible form memory. Generally, viscosity of ink is high at low temperature and low at high temperature. Accordingly, in order to make a diameter of a nozzle large at low temperature and small at high temperature, respective forms are stored in the memory alloy 1 based on data of the viscosity of the ink. Accordingly, a form memory material attached to the inside of the head contacts with the ink all the time and changes its form in accordance with changes of the temperature of the ink. Thus, the form memory alloy serves as a second nozzle by keeping quantity of ink drips ejected from the nozzle constant, so that the density of a print type can be kept constant.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an inkjet printer head [Prior Art] Conventionally, in on-demand type inkjet printer heads, the nozzle hole diameter is fixed. Since the ink temperature is constant during use, the viscosity and other characteristics of the ink change as the ink temperature increases, causing changes in the density of the print.
It was difficult to print at the same print density all the time.

[Problem to be solved by the invention] However, the structure of the inksheet printer head, which is required to be miniaturized, is precise and complicated, and precision is also required in controlling the head position. Providing a mechanism for changing the nozzle diameter on the head increases the size and complexity of the head, and it is also difficult to keep costs low.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and it is possible to solve the problems described above without making the inkjet printer head larger or more complicated. An object of the present invention is to provide a head capable of keeping the density of printed matter constant.

To achieve this objective, the nozzle of the inkjet printer head of the present invention is provided with a nozzle diameter changing mechanism made of a shape memory material that does not require a complicated mechanism and can change its shape in response to changes in temperature.

[Function] The present invention having the above-mentioned configuration allows the shape memory material to memorize a desired shape in advance based on changes in characteristic values due to the temperature of the ink, and to memorize it based on changes in the temperature of the ink. By changing the shape, the amount of ink droplets ejected from the nozzle can be automatically controlled and the density of the printed material can be kept constant.

[Example 1] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged sectional view of the nozzle portion of the inkjet printer head of the present invention. The T1Ni shape memory alloy 1 is attached to the back side of the nozzle 2, that is, inside the head after its shape is memorized.

Further, the T1Ni shape memory alloy 1 has been subjected to a reversible shape memory treatment as shown in FIG. 2ab.

Ink generally has high viscosity at low temperatures and low viscosity at high temperatures. Therefore, the nozzle diameter is large at low temperatures,
Each shape is memorized based on data on the viscosity of the ink so that the nozzle diameter becomes smaller when the temperature is high. Next, FIG. 3 shows the state of the shape memory alloy during operation.

The shape memory material attached inside the head is constantly in contact with ink and changes its shape as the ink temperature changes. As described above, in this embodiment, the shape memory alloy plays the role of the second nozzle, and the amount of ink droplets ejected from it can be kept constant, so that the density of the printed material can be kept constant. Further, if the shape is as shown in FIG. 4a, it is possible to close the nozzle portion. Furthermore, as shown in Figure 4, the same result can be obtained even if the nozzle itself is made of a shape memory alloy and its shape is directly changed.This method requires fewer parts, but there is a limit to the change in nozzle diameter. (The recoverable change in TiNi shape memory alloy is only a few percent.) Therefore, if the ink exhibits too large a change in characteristics, the shape may not follow. However, if it is possible to control the appropriate amount of ink in this way, different mechanisms can be used, but it is preferable to have a mechanism with fewer parts and a simpler mechanism in terms of cost and miniaturization of the head.

Furthermore, other than T1Ni shape memory alloy, such as C
It is also possible to use a material such as a u-Zn-A1 shape memory alloy or a plastic that exhibits a shape memory effect.

In this example, the shape memory of the shape memory alloy that changes the nozzle diameter is memorized so that the nozzle diameter increases at low temperatures and decreases at high temperatures, based on the characteristics of the ink. By providing a memory, it is possible to have a small nozzle diameter at low temperatures and a large change at high temperatures. In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit thereof.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, the nozzle diameter changing mechanism using a shape memory material enables printing at low cost without increasing the size or complexity of the inkjet printer head. It is possible to provide a head that can always keep the density of fonts constant.

[Brief explanation of the drawing]

1 to 4 show an embodiment embodying the present invention. FIG. 1 is an enlarged sectional view of the nozzle portion of the inkjet printer head, and FIG. 2(a) is a reversible shape. FIG. 2 is an explanatory diagram showing from the front the change in shape of the memory-treated T1Ni shape memory alloy at high temperature and low temperature;
Figure (b) is an explanatory diagram showing from the side the change in shape between high temperature and low temperature of the T1Ni shape memory alloy that has been subjected to reversible shape memory treatment, and Figure 3 shows the state of the shape memory alloy in the nozzle during operation. FIG. 4(a) is an explanatory diagram showing another example of the shape change of the nozzle shape in the shape memory alloy, and FIG. 4(b) is an explanatory diagram showing another example of the shape change of the nozzle shape in the shape memory alloy. It is an explanatory view showing another example. In the figure, 1 is a shape memory alloy, 2 is a nozzle, and 3 is an ejected ink droplet. Fig. 1'in2 Fig. (a) Hole ↓ I6゜5'jL 3I I ←--11--1111-inik) 1〉D Fig. 4 (a) (b)

Claims (1)

[Claims] 1. In an inkjet printer head, the nozzle part or the nozzle itself is equipped with a shape memory material that exhibits a reversible shape memory effect, and the transformation temperature and deformation amount of this shape memory material are adjusted in advance according to the temperature change of the ink during use. An inkjet printer head that is capable of storing information.