JPH02103198A - Ink jet head - Google Patents

Abstract

PURPOSE:To form an ink jet head excellent in reliability and life and capable of expressing gradation by arranging a pair of heating elements to the upper and under surfaces of an ink emitting flow passage to drive the same respectively independently. CONSTITUTION:Heating elements 6 imparting heat energy are formed to an upper substrate 1 and a lower substrate 2 on the side of fluid grooves formed by an interval 3 and emitting orifices are formed on the side of common electrodes 7. By this structure, ink is usually emitted by the heating element 6 of one substrate and, when nozzle impossible to drive is generated by the deterioration of the heating element 6, this emission can be changed over to the emission due to the heating element row of the other substrate. Or, by alternately driving the upper and lower substrates, the life of the substrates can be extended by several times as compared with a case continuously using one substrate. Further, by simultaneously driving the upper and lower heating elements and changing the pulse widths of the respective elements, an emitting amount can be adjusted and controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet head for an inkjet printer.

[Conventional technology]

In the conventional inkjet head of an inkjet printer that ejects and ejects ink using thermal energy, one heating element, which is a thermal energy generating means, is provided for each ejection opening.

(Problems to be Solved by the Invention) However, conventional inkjet heads have the following problems.

■Inkjet heads that eject ink using thermal energy often have a failure mode due to deterioration of the heating element.If even one of the heating elements corresponding to the total number of nozzles deteriorates, a dot will drop out and the head must be replaced. It won't happen.

■The amount of ink ejected is determined mostly by the thermal energy generated when the heating element is heated. Therefore, in a head where the diameter (cross-sectional area) of the nozzle and the distance from the ejection surface to the heating element are fixed, the ejection amount cannot be changed arbitrarily.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art, and its purpose is to provide an inkjet head that has excellent reliability and longevity, and is capable of expressing gradations.

[Means to solve problems]

In the inkjet head of the present invention, one heating element per ejection port was conventionally arranged on one side of the upper or lower surface of the ejection port, but the substrate forming the heating element is placed on the upper and lower surfaces of the ink ejection port. It is characterized in that it is arranged symmetrically and a pair of upper and lower heating elements are provided for one ink ejection port.

Furthermore, the heating element array on the upper surface and the heating element array on the lower surface can be driven independently.

(Embodiment) Fig. 1 shows an embodiment of an inkjet head according to the present invention, in which 1 is an upper substrate and 2 is a lower substrate.A heating element that applies thermal energy to this substrate is a fluid It is formed toward the groove side. 3 is a partition wall for forming a fluid groove.
4 is an ink ejection port. Reference numeral 5 denotes a channel tube for supplying ink, which can also be placed on the upper substrate or lower substrate side. FIG. 2 is a plan view of the substrate 1 or 2 viewed from the flow path side, in which 6 is a heating element that supplies thermal energy, 7 is a common electrode, and 8 is an individual electrode. The flow path is formed in the direction of the dashed line in the figure, and the common electrode side becomes the discharge port. In addition, the electrodes are pulled out using a flexible printed connector (FPC), etc. using the outside of the broken line.
Therefore, in this example, the FPC is attached to the side of the head.

Further, inside the broken line in the figure, a heat-resistant insulating film such as 8102 covers the heating element and electrodes. - The numerical thickness is less than or equal to 2 μm. These substrates are arranged symmetrically with the partition walls in between. Various methods can be considered for joining to the partition wall, depending on the material, such as thermocompression bonding, adhesives, and welding. By bonding an FPC to this head and connecting an ink flow pipe, it becomes possible to drive the head. Further, in order to improve the thermal balance, a heat sink made of A1 or the like may be placed on the substrates 1 and 2. Needless to say, the substrate Mi1
．． Reference numeral 2 denotes an insulating substrate, and the electrode shape, heating element shape, etc. are not particularly limited, and the material is also the same. FIG. 3 shows a cross-sectional view of the flow path, and numeral 9 is a protective film.

This head is connected to an electric circuit via an FPC, and the heating element on the upper substrate and the heating element on the lower substrate can be driven independently on the circuit.

By doing this, ink is normally ejected using the heating element on one side of the board, but if a nozzle that cannot be driven occurs due to deterioration of the heating element, etc., it is possible to switch to ejection using the row of heating elements on the other side of the board. .

Basically, the position of the heating element is simply changed from the top surface to the bottom surface, and there is no effect on the discharge characteristics.Alternatively, by driving the top surface and bottom surface alternately, the heat generation is increased compared to when one side is used continuously. It is also possible to extend the body's lifespan several times.

Furthermore, by driving the upper and lower heating elements simultaneously and changing the pulse width of each upper and lower heating element, the discharge amount can be adjusted and controlled. In this case, area gradation is possible with one nozzle, and in experiments it was possible to produce up to 16 gradations.

〔Effect of the invention〕

As explained above, by arranging a pair of heating elements on the upper and lower surfaces of the ink ejection channel and allowing each to be driven independently, it has become possible to more than double the life of the head. Furthermore, it becomes possible to adjust the ejection amount, which was difficult in the past, which is very advantageous when configuring a full-color printer.

As described above, the effects of the present invention are extremely large, such as greatly improving the reliability of the inkjet head and facilitating color printing.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an inkjet head according to the present invention, FIG. 2 is a block diagram of the substrate shown in FIG. 1, and FIG. 3 is a sectional view of an ink flow path. 1... Upper substrate 2... Lower substrate 3... Channel partition wall 4... Discharge port (ink channel) 5... Ink supply tube 6... Heating element 7... Common electrode 8 ...Individual electrode 9...Protective film or more

Claims (2)

[Claims] (1) An inkjet head comprising at least a plurality of liquid ejection ports for ejecting ink using thermal energy to form dots, and a plurality of thermal energy generating means corresponding to the ejection ports. , characterized in that the substrates forming the thermal energy generating means array are arranged symmetrically on the upper and lower surfaces of the liquid discharge port, and a pair of upper and lower thermal energy generating means is provided to one liquid discharge port. inkjet head. (2) The inkjet head according to claim 1, wherein the energy generating means array on the upper surface and the energy generating means array on the lower surface can be driven independently.