JPS5838110B2 - Manufacturing method of inkjet head - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing an inkjet head.

FIG. 1 shows an example of an inkjet head, and is an explanatory diagram of the principle of an ink-on-demand type inkjet head.

The ink liquid supplied from the ink liquid supply pipe 10 fills the passage up to the ink liquid jet port 11, and the piezo element 12
The ink liquid is pressurized by the bending deformation of the pressure plate 13 based on the application of a voltage pulse to the ink liquid, and the ink liquid is ejected from the ink liquid ejection port 11 to obtain a desired record on the recording paper.

Conventionally, manufacturing inkjet heads, especially multi-nozzle ink-on-demand type inkjet heads, has been extremely difficult, and establishing a manufacturing method is one of the important issues in commercializing inkjet heads. It is one.

The difficulty of manufacturing is that the entire structure, including the ink jet nozzle, requires a fine structure and high dimensional accuracy.In terms of materials, there are constraints from ink resistance, strength to withstand ink pressure and disturbances, etc.
This is due to the strong demand for lower costs, etc.

FIG. 2 is for explaining an example of a method of manufacturing an inkjet head that we have tried. First, a recess 15 that will become an ink liquid passage is formed on the surface of a glass plate 14 by etching.

Next, after applying a thin layer of adhesive to the convex portions (unetched portions) 21 so as not to flow into the concave portions 15, another thin glass plate (pressure plate) having a thin or thick conductive layer 17 on its surface is applied.
Glue 16.

By adhering the piezo element 18 onto the conductive layer 11, attaching the ink liquid supply pipe 19, and wiring the piezo element 18, the inkjet head is almost completed.

However, the above-mentioned manufacturing method has the following problems.

In other words, it is extremely difficult to apply or bond an adhesive that has the strength to seal against ink liquid, to withstand pressure and disturbance, and does not flow into the recess 15, and requires sophisticated techniques and long manufacturing time. In a multi-nozzle type inkjet head, it is difficult to always make each ejection port 20 and the passage leading to each ejection port 20 uniform without the adhesive protruding, and also the long-term durability and ink liquid resistance of the adhesive. There are problems with characteristics, etc.

Incidentally, the depth of the recess 15 is approximately 50 μm, the width of the recess at the ink jet port is approximately 50 μm, and the distance between adjacent recesses (width of the convex portion) is approximately 100 to 200 μm at the minimum.

As a method of improving the drawbacks of the above-mentioned manufacturing method, as shown in FIG. 3, it is also possible to use solder instead of the above-mentioned adhesive.

A solder layer 22 is formed on the glass plate 14 and the thin glass plate 16, and the glass plates 14 and 16 are bonded by applying pressure, bringing them into contact, and heating them.

However, in this method, since a metal layer is interposed between the two glass plates 14 and 16, it may break when exposed to temperature changes during bonding or after completion, and the corrosion resistance of the solder layer may deteriorate. However, there are drawbacks such as problems with the quality of the product and an increase in manufacturing costs due to the complexity of the manufacturing process.

The present invention aims to eliminate the drawbacks of the inkjet head manufacturing methods that have been proposed or attempted in the past, and to propose a manufacturing method that is highly reliable and mass-producible.

The present invention will be explained below.

As shown in FIG. 4, first, a recess 15 that will become an ink liquid passage is formed on the surface of the glass plate 140 by etching.

As described above, the depth is about 50 μm, the width of the concave portion of the ink liquid jetting port is about 50 μm, and the jetting pitch is about 300 μm when the number of jetting ports is 12.

Accurate etching makes it possible to create a complex shape with many curves and a fine but highly accurate recess 15.

A thin glass plate (pressure plate) 16 is stacked on the glass plate 14, and moderate pressure is applied from both sides in the direction of the arrow using a jig 23 made of a heat-resistant material such as ceramic.

The glass plate 14 has a thickness of about 0.5 to 1, and the pressure plate 16 has a thickness of about 0.5 to 1.
．． 15-0. It is about 2 mm.

The jig 23 corrects the warpage that tends to occur in the thin pressure plate 16, and makes the two glass plates 14, 160 in perfect contact.

Both glass plates 14 and 16, which have been brought into close contact with each other by the jig 23, are then placed in an electric furnace, and heat fusion is performed on the contact surfaces.

The conditions for heat fusing are that both glass plates do not undergo deformation, or even if deformation does occur, the deformation is kept to the minimum allowable amount, that no breakage occurs when cooled to room temperature, and that the ink liquid is sealed. There should be no defects in the strength against liquid pressure or disturbance.

To meet these conditions, it is essential to manage the thermal conditions of the electric furnace, including heating rate, maximum temperature, maximum temperature holding time,
The cooling rate must be carefully determined taking into account the characteristics of the glass plate.

Of course, it goes without saying that once it is determined, stable heat fusion can be obtained at all times.

The thermal properties of the glass change depending on the heating rate, so once the heating rate is set, the heating rate should always be the same, the maximum temperature should be within the range where no deformation occurs, and the cooling rate should be kept at least slowly cooling above the transition point. However, below this limit, damage due to temporary strain will not occur.

A large difference in the coefficient of thermal expansion between the glass plates 14 and 16 may cause breakage, so both glass plates 14 and 16 are preferably made of the same type of glass.

However, by appropriately selecting the type of glass, it is also possible to thermally fuse different types of glass plates together, and experimental results have been obtained that are better in thermally fusing different types of glass from the viewpoint of deformation during thermal welding.

After heat fusion, a thin or thick conductive layer 17 is formed on the pressure plate 16 as shown in FIG. , wiring to the piezo element 18, and attaching the cover.

FIG. 6 shows an embodiment of an inkjet head to which the manufacturing method according to the present invention is applied.

Recesses to serve as ink liquid passages were formed on both surfaces of the glass plate 14 by etching, and thin glass pressure plates 16 and 24 were heat-sealed to both surfaces. 20, 25 in the figure
is an ink liquid jetting port, and each jetting port is arranged alternately, and for example, three
This is an inkjet head that needs to be equipped with a large number of ink liquid ejection ports, such as two.

In this case, since the three glass plates 14, 16, and 26 can be overlapped and heat-sealed at the same time, there is no difference in manufacturing compared to the previous heat-sealing of two glass plates.

As explained above, the method for manufacturing an inkjet head according to the present invention is simple, and it is possible to obtain a highly reliable inkjet head.More specifically, it has the following effects. There is.

That is, the manufacturing method according to the present invention is very simple,
If a belt furnace is used as the electric furnace, automation is possible, and the cost of the inkjet head can be lowered due to high mass productivity and improved yield.

According to the manufacturing method of the present invention, it is stable over a long period of time because it does not have the problem of ink resistance like adhesives, has high strength, and always provides a uniform and consistent ink liquid path. A highly reliable inkjet head can be obtained.

Furthermore, the glass substrate and pressurizing plate used are of common types, such as white plate glass, blue plate glass, Pyrex, and other inexpensive glass materials that are commonly available on the market, and are very advantageous in terms of price.

Note that the present invention is applicable not only to the production of ink-on-demand type inkjet heads but also to the manufacture of other types of inkjet heads such as charge control type, and the scope of the claims is not limited thereto.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an inkjet head, FIGS. 2 and 3 are explanatory diagrams of an example of a method for manufacturing an inkjet head, and FIGS. 4 and 5 are explanatory diagrams of an example of a manufacturing method according to the present invention. FIG. 6 shows an example of an inkjet head using the manufacturing method according to the present invention. 10... Ink liquid supply pipe, 11... Ink liquid injection port, 12... Piezo element, 13...
...Pressure plate, 14...-Glass plate, 15...
...Recess, 16...Pressure plate, 17...
...Conductive layer, 18... Piezo element, 19...
... Ink liquid supply pipe, 20 ... Ink liquid injection port, 21 ... Convex part (unetched part), 22.
...Solder layer, 23...Jig, 24...
... Pressure plate, 25 ... Ink liquid jet port.

Claims (1)

[Claims] 1. A method for manufacturing an inkjet head, which comprises: heat-sealing a glass plate with a recess formed on its surface and another glass plate to each other on the surface to create a passage for ink liquid in the recess.