JPH02137930A - Ink jet head - Google Patents

Abstract

PURPOSE:To effectively prevent change of properties and deterioration of ink by providing a conducting circuit for supplying power to an electric heater mounted in a gas chamber in contact with an ink chamber through an elastic diaphragm, and heating to expand gas isolated through the diaphragm to inject ink droplets. CONSTITUTION:Heaters 5a-5n and feeder pairs (6a, 7a)-(6n, 7n) for supplying powers to the heaters are formed on an insulating board in air chambers 3a-3n. Conducting circuits including the feeder pairs (6a, 7a)-(6n, 7n) selectively and intermittently supply powers to the heaters 5a-5n according to printing information to selectively abruptly heat to expand the airs filled in the corresponding air chamber. For example, if the power is supplied only to the heaters 5b, 5c, 5e to heat the airs only in the chambers 3b, 3c, 3e to be abruptly expanded, volumes of the ink chambers 2b, 2c, 2e are narrowed by elastic diaphragm 4, the inks are injected forward from corresponding ink discharge ports to be adhered to a sheet on a platen.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an inkjet head that constitutes an inkjet printer.

(Conventional technology)
Various jetting methods are used in heads, but
One of them is the bubble jet method.

As shown in the cross-sectional view of FIG. 5, this bubble jet method includes an ink discharge port 21 formed in front of the head, an ink chamber 22 that supplies ink to the ink discharge port 21, and an ink chamber 22 that supplies ink to the ink discharge port 21.
The ink chamber includes an electric heating element 23 installed in the ink chamber and an energizing circuit (not shown) for supplying power to the electric heating element. When a large amount of power is instantaneously supplied to this electric heating element 23 to heat it, bubbles 30 are rapidly generated and expanded in the ink chamber as shown in FIG. An amount of ink droplets approximately equal to
It is injected in front of 1.

(Problems to be Solved by the Invention) In the conventional bubble jet type inkjet head described above, the ink itself is heated by an electric heating element, so the ink may change in quality as the temperature rises or contain impurities. There is a problem that it deteriorates as it occurs. Particularly in continuous-jet inkjet heads, in which ink is continuously ejected and parts unnecessary for printing are collected by a gutter and reused, alteration and deterioration of the ink due to repeated heating becomes a problem.

(Means for Solving the Problems) The inkjet head of the present invention includes an ink ejection port formed at the front of the head, an ink chamber for supplying ink to the ink ejection port, and an ink chamber connected to the ink chamber via an elastic diaphragm. It is equipped with a gas chamber that is in contact with the gas chamber and is filled with gas, an electric heating element installed in the gas chamber, and an energizing circuit that supplies power to the electric heating element, and is capable of heating and heating the gas separated by an elastic diaphragm.
By expanding and ejecting ink droplets, the ink is configured to effectively prevent deterioration and deterioration of the ink.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

(Embodiment) FIGS. 1 and 2 are sectional views showing the structure of an inkjet head according to an embodiment of the present invention, respectively. Figure 2 shows B-B in Figure 1.
'This is a cross-sectional view.

In this inkjet head, there are n ink chambers 2a, 2b, 2 in a direction perpendicular to the direction of ink flow.
c...2n are formed, and ink ejection ports 1a and lb are formed at the tip of each ink chamber.

lc...In is formed. That is, similar to the conventional bubble jet system, ink ejection ports 1a to 1a are emitted through n ink chambers 3a to 3n divided from a common ink chamber (not shown) formed at the rear of the head.
Ink is supplied to each of 1n. Ink chamber'la
, 2b, 'lc...2n, air chambers 3a, 3b, 3c are in contact with each ink chamber through an elastic diaphragm 4.
...3n is formed. The elastic diaphragm 4 is made of a material such as rubber that is stretchable, heat resistant, and airtight, and keeps the corresponding air chamber filled with air at approximately atmospheric pressure.

Inside the air chambers 3a to 3n, heaters 5a to 5n and pairs of power supply lines (
6a, 7a) to (6n, 7n) are insulating substrates 8
formed on top. Pairs of feeder lines (6a, 7a) to (6
Each of the energizing circuits including the heaters 5a to 7n selectively and intermittently supply power to each of the heaters 5a to 5n according to the printed information, thereby selectively discharging the air filled in the corresponding air chamber. Heat rapidly and expand. for example,
If power is supplied only to the heaters 5b, 5c, and 5e, and the air only in the air chambers 3b, 3c, and 3e is heated and expands rapidly, the air will expand rapidly as shown in the cross-sectional views of FIGS. The ink chambers 2b, 2c,
The volume of 2e is narrowed, and the narrowed amount of ink is ejected from the corresponding ink ejection ports lb, lc, and le to the front of the head and adheres to the paper surface on a platen (not shown).

The expanded air in the air chamber is cooled by the ink through the elastic diaphragm and contracts, returning to the state before heating.

As described above, a plurality of sets of ink ejection ports, ink chambers, gas chambers, electric heating elements, and energizing circuits are formed in a direction perpendicular to the flow of ink, and each set of heating elements is selectively and intermittently operated according to printed information. The present invention has been described in the case of an on-demand inkjet head that is energized.

However, the present invention can also be applied to a continuous type inkjet head in which each energizing circuit periodically energizes a corresponding electric heating element, and parts unnecessary for printing are collected via a gutter. You can also do it. In this continuous type, an appropriate type of deflection mechanism for separating ink necessary for printing from ink unnecessary for printing can be applied, such as an electrostatic deflection mechanism using a combination of a charging electrode and a deflection electrode.

Further, the present invention can also be applied to a simple inkjet head that has only one ink ejection port and prints simple symbols such as bar codes by main scanning of recording paper.

(Effects of the Invention) As explained in detail above, the inkjet printer of the present invention
The head heats and expands gas separated by an elastic diaphragm to eject ink droplets, effectively preventing the deterioration and deterioration of ink that is a problem with conventional bubble jet methods that directly heat ink. It is played.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing the structure of an inkjet head according to an embodiment of the present invention, and FIGS. 5 and 6 are cross-sectional views showing the structure of a conventional bubble jet type ink chef head. It is a diagram. 1a to 1n... Ink discharge port, 2a to 2n... Ink chamber, 3a to 3n... Air chamber, 4... Elastic diaphragm, 5
a to 5n...Heating element, (6a. 7a) to (6n to 7n)...Pair of power supply lines included in each energizing circuit, 8...Insulating substrate. Patent applicant: NEC Home Electronics Co., Ltd.

Claims (5)

[Claims] (1) An ink discharge port formed in the front of the head, an ink chamber that supplies ink to the ink discharge port, a gas chamber that is in contact with the ink chamber through an elastic diaphragm and is filled with gas, and this gas chamber An inkjet head characterized by comprising: an electric heating element installed in the inkjet head; and an energizing circuit that supplies power to the electric heating element. (2) The inkjet head according to claim 1, wherein the energizing circuit includes means for periodically energizing the electric heating element. (3) The inkjet head according to claim 1, wherein the energizing circuit includes means for intermittently energizing the electric heating element in accordance with print information. (4) A plurality of sets of the ink ejection ports, ink chambers, gas chambers, electric heating elements, and energizing circuits are formed in a direction perpendicular to the flow of ink, and the heating elements of all sets are periodically energized. An inkjet head according to claim 1, characterized in that: (5) A plurality of sets of the ink ejection ports, ink chambers, gas chambers, electric heating elements, and energizing circuits are formed in a direction perpendicular to the ink flow, and each set of heating elements is selectively and electrically heated according to the printed information. 2. The inkjet head according to claim 1, wherein the inkjet head is energized intermittently.