JPS6322988B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink-on-demand type inkjet head.

In general, printing devices using ink-on-demand type inkjet heads are non-impact type, and therefore generate less mechanical noise. Furthermore, there is no need to use special thermal paper for the printing object; ink can be easily dotted onto the surface of objects made of not only plain paper but also objects such as metal and plastic, which are not necessarily flat. It has the characteristic that it adheres in the form of dots and prints can be made by combining these dots. In addition, the overall configuration of the printing device is simple and compact, the printing speed is fast,
It is characterized by low printing energy, and by using a nozzle with a fine hole diameter, it is possible to print with extremely high dot density.
Print quality can be improved. It is particularly important that the diameter of the nozzle hole is about 30 to 200 .mu.m to provide good printing characteristics, and that the nozzle hole is precisely formed in a predetermined shape.

However, as mentioned above, the nozzle hole is extremely minute with a diameter of about 30 to 200 μm, so the nozzle itself may be made of a hard material, or it may be made of a relatively soft material. Even in this case, drilling the nozzle hole with high precision is a very difficult task. The nozzle hole is formed by drilling a hole in a metal material with a thin drill, or by etching a metal material, glass material, etc. into a predetermined shape by photoetching to form a groove for the nozzle hole. It is also conceivable to form a nozzle hole by pasting a plate material to serve as a lid.
However, drilling holes with an extremely thin drill makes it difficult to maintain hole diameter accuracy (usually ±2 μ or less) during mass production, and when trenches are dug (formed) by photo etching, the inner wall surface of the trench may have fine irregularities. In addition, the corners should be gently etched and not sharp, and the adhesive used to attach the plate material that becomes the lid may flow into the nozzle hole and change the shape of the nozzle hole. When the amount of inkjet head is small, adjacent grooves often communicate with each other and become useless as an inkjet head. Furthermore, when bonding plate materials with glass, a similar situation occurs when adhesive is used. It cannot be said that a method for easily manufacturing an ink jet head having fine nozzle holes with such precision and good printing quality with a high yield has yet been established. Therefore, the reality is that an ink jet head with ideal print quality has not been obtained.

The present invention was developed in view of the above-mentioned circumstances, and after pressing and molding a press plate having the shape of an ink supply section, a pressurizing chamber, a nozzle hole, etc. onto the surface of an unfired ceramic green sheet, The aim is to produce an inkjet head made of ceramic and having highly accurate nozzle holes by laminating another ceramic green sheet serving as a lid member and firing it.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 shows a plate-shaped ceramic body C which is a semi-finished product of an ink jet head according to the present invention, and has an ink supply section S, a pressurizing chamber P, an ink circulation groove R, and a nozzle hole N, except for those not actually shown in the figure. Ceramic plate-like bodies are stacked on top of each other to form an integrated structure.

FIG. 2 shows the manufacturing process of an inkjet head according to the present invention.

First, a ceramic green sheet 1 before firing is used as a base substrate for forming the nozzle of the present invention. The ceramic green sheet 1 is produced by forming a slurry using, for example, a doctor blade method, or generally by forming a slurry from ceramic raw material powder, a plastic organic material, and a solvent, and forming the slurry into a sheet of a desired thickness. It is made by punching or cutting a sheet obtained by this method into a predetermined shape. Therefore, this ceramic green sheet 1 itself is relatively soft and plastic, and can be freely deformed by hand.

Therefore, in system (A) of the manufacturing system shown in FIG. By pressing against the ceramic green sheet 1 so that at least the upper surfaces of the template 2A and the ceramic green sheet 1 are on the same plane, the pressure is stopped and the template 2A is removed from the ceramic green sheet 1. , a recess is formed. On the top surface of the ceramic green sheet 1 in which the recesses 3 forming the pressurizing chambers, ink circulation grooves, nozzle holes, etc. are formed, the ceramic sheet 4 forming the lid member is further superimposed, and both sheets 1 and 4 are bonded together by thermocompression bonding. By adhering and then firing in an oxidizing atmosphere at 1300 to 1600°C, an ink jet head H having ink flow grooves R etc. in the ceramic body 5 is manufactured.

Next, the manufacturing process of another system is shown in B, in which synthetic resin,
After placing (or adhering to) a template 2B made of an organic material such as wood or paper, or a material that has the property of disappearing such as decomposing or sublimating due to heat, the template 2B is not shown. The pressing means is used to press the ceramic green sheet 1 so that at least the upper surfaces of the template 2B and the ceramic green sheet 1 are flush with each other. That is, a template 2B is embedded in the ceramic green sheet 1, and a ceramic sheet 4 forming a lid member is placed on the top surface of the template 2B.
The template 2B itself, which is made of an organic substance or a material that has the property of disappearing with heat, is made by placing the template B, bonding both sheets 1 and 4B by thermocompression bonding, and then firing it in an oxidizing atmosphere at 1300 to 1600°C. As a result of burning or decomposition and disappearing, an ink jet head H having an ink flow groove R, a pressurizing chamber P, etc. in the ceramic body 5 is manufactured. Note that instead of thermocompression bonding in both steps, it is also possible to apply an adhesive liquid (organic binder) to the lid member 4 and then press-bond it, or it is also possible to apply a adhesive liquid and then perform thermocompression bonding.

By the way, the lid member 4A is made of ceramic body 5 after firing.
The outer surface of the skin 5a is as thin as 0.1 to 0.2μ, and the outer surface of the skin 5a has grooves R, for example.
Means for generating or applying mechanical vibration is provided to pressurize the ink accumulated therein and cause it to be ejected as ink particles from the nozzle hole N provided at the tip. On the other hand, as shown in the manufacturing process of system (B), an electrode (see FIG. By applying a predetermined driving voltage to the electrode, the skin 5a made of piezoelectric ceramic vibrates in proportion to the voltage, thereby instantaneously pressurizing the ink in the groove R, and Ink droplets are ejected from a predetermined nozzle hole N in the part, and characters, marks, etc. are printed on the surface of paper or articles by combining the dots formed by the adhesion of the ink droplets.

Example 1 A metal mold with a thickness of 0.08 mm and shaped like ink grooves and nozzle holes was placed on a ceramic green sheet with a thickness of 1.2 mm, and the mold was heated at a temperature of 85°C.
After forming a concave shape by applying a pressure of 780 kg/cm ² for 3 minutes under Seshime, then 1300-1600
Calcined in an oxidizing atmosphere at ℃.

As a result, the depth of the pressure chamber, ink groove, etc. is collapsed to about 10μ during thermocompression bonding, and the overall size is reduced by 15 to 25% compared to before firing, but the ink groove and nozzle hole are clogged. An inkjet head that can print dots with a predetermined clear shape, with no leakage (circulation) between ink grooves, and almost no deformation of the cross-sectional shape of the ink grooves or nozzle holes. was able to produce.

Example 2 A ceramic green sheet similar to that of Example 1 above was formed with ink grooves, nozzle holes, etc.
A mold made of acrylic sheet, which is a plastic film of 0.08 mm, is placed, and a pressure of 780 kg/cm ² is applied to the mold for 5 minutes at room temperature to at least remove the top surface of the mold and the ceramic green sheet. A press mold is embedded in the ceramic green sheet so that the surfaces are on the same plane, and another ceramic green sheet is placed on the top surface corresponding to each ink groove to serve as a lid member (skin) that applies ink ejection pressure on the same plane. After layering piezoelectric ceramic sheets such as barium titanate and bonding both sheets tightly by thermocompression bonding,
It was fired in an oxidizing atmosphere at 1300-1600℃. Thereafter, drive electrodes are provided on each skin made of piezoelectric ceramic body.

By applying a predetermined voltage to the electrodes of the ink jet head manufactured in this way, the skin vibrates, which applies pressure to the ink in the ink grooves, causing the ink to eject in the form of particles from the corresponding nozzle holes. However, even when manufactured in this way, the overall size is 15 to 25% smaller than before firing, and there is no leakage between the ink grooves, and there is no leakage between the ink grooves. Almost no deformation of the cross-sectional shape of the nozzle hole was observed, and an ink head capable of depositing dots with a predetermined clear shape could be manufactured.

In addition, the plastic mold that was initially embedded in the ceramic green sheet and remained in the green sheet thermally decomposed even at the high temperature during firing, and the disappeared part became the ink groove,
It serves as a pressure chamber, nozzle hole, etc.

The ink jet head according to the present invention as described above is made of a ceramic sheet and is extremely thin, and can be laminated in multiple layers to eject ink of various colors from other nozzle holes to construct a color printer. It is also easily possible to
Furthermore, by printing a predetermined conductive pattern 6 with metallization paste on the back side of the ceramic green sheet 1 before firing, as shown by the broken line in the figure, a printed circuit board can be attached. It is also possible to integrally construct the inkjet head and the electronic circuitry that drives them in a compact manner.

As described above, according to the present invention, a ceramic green sheet is pressure-molded into a predetermined shape and then fired, making it possible to create an inkjet head with highly accurate pressure chambers, ink grooves, nozzle holes, etc. It is easy to manufacture, and stable nozzle characteristics can be maintained over a long period of time due to the abrasion and corrosion resistance of the ceramic body after firing. By utilizing the excellent insulating properties and printing a conductive pattern before firing, the head itself can be used as a printed circuit board, and electronic circuits can be formed using the printed circuit board, making the head and drive circuit compact. It is possible to summarize. Furthermore, since a heating resistor pattern can be embedded in the ceramic body that forms the head, it is possible to easily maintain a constant temperature, which is a major factor that affects the state of ink ejection. It is possible to provide an inkjet head with a

[Brief explanation of the drawing]

FIG. 1 is a broken cross-sectional view showing an example of an ink jet head, and FIG. 2 is a process flow diagram illustrating a method for manufacturing an ink jet head according to the present invention. H: ink jet head, R: ink groove,
1: Ceramic green sheet, 2A, 2B: Press mold, 4A, 4B: Lid member.

Claims (1)

[Claims] 1. A step of placing and pressurizing a press plate in the shape of an ink ejection operating section such as an ink supply section, a pressurizing chamber, an ink circulation groove, and a nozzle hole on a ceramic green sheet, and a process of pressurizing the ceramic green sheet by pressure molding with the press plate. A method for manufacturing an ink jet head, the method comprising the step of firing a sheet.