JPS60151062A - Manufacture of converter row - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an impulse inkjet printhead, and more particularly to a method of manufacturing a transducer array for use in an impulse inkjet printhead from a single transducer sheet.

BACKGROUND OF THE INVENTION Inkjet devices, particularly impulse inkjet devices, are well known. Basically, this type of impulse device uses short pressure pulses to eject ink droplets from the ink chamber through a small nozzle onto the print surface, forming an image in a specific pattern. Each drop is created by pressure waves within the liquid. Pressure waves are generated by applying voltage pulses to a transducer, such as a piezoceramic material. The term impulse or required drop is used in the known literature and herein to refer to an ink jet device in which there is no limit to the rate or frequency of ink drop ejection other than nozzle refill sump recovery time. That is, droplets can be ejected at any desired rate with or without pattern, sequence, or rhythm.

The principle of an impulse ink jet is the compression of ink and subsequent ejection of ink droplets from the ink chamber through a nozzle; the drive mechanism for this consists of a transducer material, such as a piezoelectric ceramic, bonded to a thin diaphragm. When a voltage is applied to the piezoelectric ceramic material, the piezoelectric ceramic tends to change its planar dimensions, but since it is firmly and rigidly bonded to the diaphragm, bending occurs. In impulse jets, dimensional changes based on electrical impulses of a transducer diaphragm structure or drive mechanism are used to provide pressure to the ink. For example, in a rectangular piezoceramic transducer, the transducer material is bonded to a flexible diaphragm material that has a strength close to that of the transducer material.

The diaphragm and transducer must flex when the transducer is expanded or contracted by the applied voltage. Thickness: 5 mils (approx.
For example, the standard drive voltage for extruding ink droplets from the nozzle in an impulse manner in a 13 mm transducer is 100 mm.
It is. The impulse lasts, for example, 20-40 milliseconds and expels a 4 microinch drop at 1 atmosphere. Refilling of the ink after a drop has exited the nozzle is accomplished by capillary action at the nozzle. Refill typically takes about 100 microseconds and varies depending on ink viscosity, surface tension, and fluid path impedance. The hydrostatic pressure of the approximately 1 in (approximately 25 mm) layer balances the capillary action.

A bank of ink jets or ink jet heads requires a bank of transducers. Typically, each transducer is individually adhesively mounted adjacent to the ink chamber of each jet.

The problem that arises in this case is that when the number of transducers in a row is, for example, 12 or more, handling becomes complicated, resulting in handling problems such as breakage. Furthermore, the time and component cost of gluing individual transducers to the diaphragm increases proportionally with the number of transducers. Furthermore, the possibility of breakage and performance variations in solution volume and velocity are increased.

Applicant's same-day application adheres a single sheet of transducer material to a diaphragm using an adhesive. If the adhesive can be omitted, energy transfer is improved because the adhesive layer does not absorb mechanical energy. Another problem is that
Without the adhesive layer, there is electrical contact between the transducer material and the diaphragm, so there is no need for electricity to pass through the adhesive layer. The adhesive layer forms a capacitive layer to reduce the electric field in the piezoelectric ceramic and reduce bending effects.

The present invention obviates the drawbacks of the known methods of manufacturing transducer arrays for impulse inkjet printheads as described above.

The present invention provides a method of manufacturing a transducer array using a single sheet of transducer material, eliminating the need to bond each individual transducer to form a transducer array. A method of manufacturing transducer arrays by coating transducer material is provided, eliminating the need for adhesives.

A method of manufacturing a transducer array for use in an Impulse Ink Ziera l-printhead according to the present invention includes coating a layer of diaphragm material on one sheet of transducer material and removing a sufficient amount of the transducer material. leaving multiple independent sections of transducer material extending from the diaphragm.

Operation The method of manufacturing a transducer array according to the invention is less expensive than known methods, the method of the invention involves fewer assembly steps, and the time required to manufacture the transducer array is significantly less.

In the method of manufacturing a transducer array according to the present invention, the transducers themselves are more uniform in size and composition than known methods, and there is less variation in the voltage required to drive each transducer.

The method of manufacturing a transducer array according to the present invention is such that the position of each transducer is
It can be on the order of a few millionths of an inch, or on the order of ±0.5 mil if the transducers are placed individually using known methods.

The method of manufacturing a transducer array according to the invention eliminates the problem of breakage of extremely brittle transducers. When handling small converter parts rather than single sheets, damage can easily occur even if handled with care (9).

The method of manufacturing a transducer array according to the invention can produce any transducer shape that can be cut from a flat sheet, and can produce transducers for different ink jet head outputs and ink path lengths.

Reference will now be made to illustrative embodiments and drawings intended to clarify objects and advantages of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transducer assembly manufactured by the method of the invention includes a piezoelectric member, preferably made of piezoceramic material. There are a variety of shapes used for impulse ink jets of piezoelectric ceramic transducers. Standard shapes include disk and tube cube. The disc is approximately 0.5Z7+, (approximately 12.7m
m) The diameter shall be as follows. The rectangle is 1 inch long and 0.1” wide.
(25.4 x 2.5 mm).

The length of the tube is approximately 0.4i''□ (approximately 10mm) and the outer diameter is approximately 0.1
Z7L (2.5mm). The transducer according to the invention has the desired shape, such as a disc or a rectangle, and has at least one plane,
That is, a receptacle surface is required to cover the diaphragm to the transducer surface. The upper surface of the piezoelectric ceramic member is coated with a conductive material, such as gold, using a spruce (10) or the like. A voltage pulse generator is connected to the conductive upper and lower surfaces via electrical leads. The gold layer makes the piezoceramic surface a conductor and allows the diaphragm material to be electroplated as described below.

To manufacture a transducer array for use in an impulse inkjet printhead according to the invention, one starts from a transducer material in the form of a sheet of piezoceramic material 1 shown in FIG. A sheet of piezoceramic material is first coated with diaphragm material 2 . This is brought into direct contact with the ink 4 portion of each ink chamber 5 of the inkjet print head 3 and fixed. The diaphragm is made of metal or an alloy, for example, and has a thickness of about 0.001 inch (about 0.025 mm).

The material forming the diaphragm has a strength comparable to that of the piezoelectric material, allowing the diaphragm and the piezoelectric ceramic to bend together when the transducer expands and contracts by applying a voltage. The coating process is preferably electroplating and coats one side of the piezoelectric ceramic sheet with the diaphragm material.

Piezoceramic (11) The surface to be plated of the sheet is coated with the required material, such as gold, to enable efficient electroplating of metals, such as nickel, onto the piezoceramic material surface.

According to the invention, permanent polarization of the piezoceramic material is performed prior to coating with the diaphragm material.

The polarization process involves subjecting the piezoelectric material to a DC voltage exceeding the coercive field of this material, e.g. 65-100"/m, 1.

After the condition of FIG. 1 is achieved, the required amount of piezoceramic material is removed to form a plurality of independent sections of piezoceramic material extending from the diaphragm.

In impulse inkjet printheads, the independent part is usually above the ink chamber 5.

With the present invention, the amount and location of the piezoceramic material removed is variable, resulting in different shapes of the transducer array. For example, as shown in FIG. 2, by removing the piezoelectric ceramic material,
Immediately above the ink chamber 5 are formed respective independent islands 6 of piezoceramic material coated in a layer of diaphragm material 2 .

During operation of the impulse inkjet printhead, the required piezoelectric (12) drive voltage applied to the ceramic island 6 causes the transducer material and the diaphragm to bend. This bending is caused by differential expansion or contraction of the transducer and diaphragm materials, creating pressure in the ink chamber directly below and ejecting the ink droplets.

It is important not to cause any damage to the extremely thin, e.g. 0.001" thick, diaphragm during the removal process of the piezoceramic material. To avoid complete removal of the piezoceramic material during the ceramic removal operation, it is necessary to remove the piezoceramic material in such a way that a plurality of independent sections 7 of piezoceramic material can be formed, as shown in FIG. However, the entire thickness of the material is not completely removed.This separate section 7 is directly above the ink chamber 5.

The thickness of the remaining piezoceramic material is significantly smaller than the thickness of the diaphragm 3, for example approximately 10 times the thickness of the diaphragm.
96 or less, the increase in the stiffness of the diaphragm above the ink chamber 5 has no significant effect on the bending of the transducer and diaphragm material during ink jetting, and the ink 4 is transferred from the ink chamber 5 to the inkjet. The pressure driving through the nozzles of head 3 is not significantly affected.

In many instances, it is desirable to mechanically strengthen the islands or isolated portions of piezoelectric ceramic material that remain after the transducer material removal process to reduce the chance that the transducer section will fail due to cracking or fatigue. To this end, according to the invention, a smooth mechanical transition 8 is formed at the interface between the piezoceramic material 9 and the diaphragm 2, as shown in FIG.

The converter structure shown in FIG. 5 is preferably used when it is desired to reduce the value of the voltage acting on the converter.

For this purpose, according to the invention two
The sheets of piezoelectric ceramic material are bonded together using an epoxy adhesive or the like.

The surface of the bonded layer is coated with diaphragm material 2 by electrodeposition or the like. In the process shown in the figure, the required piezoceramic material is removed to form a plurality of independent sections of piezoceramic material, each section being a layer 10.1 of piezoceramic material of opposite polarity.
Consists of 1. The diaph (14) ram is fixed to the inkjet print head 3 and is in direct contact on the ink 4 in each ink chamber 5.

As a transducer material removal technique, it is effective and inexpensive to remove only a portion of the transducer material, typically a thin strip, according to the present invention. FIG. 6 shows the result of the removal, with the remaining portion of transducer material 12 located not over a portion of the ink chamber 5.
There is.

Various techniques can be used to remove the transducer material to form the separate sections of transducer material shown in FIGS. 2-6 above. For example, chemical etching is a method that can be used. Most piezoelectric ceramic materials (IJ lux) are dissolved using various acid solutions, such as those containing hydrofluoric acid, phosphoric acid, fluoroboric acid, sulfuric acid, nitric acid, and hydrochloric acid. Residues can be removed by washing or mechanically. To obtain a specific corrosion pattern, the piezoceramic material is uniformly coated with a photosensitive polymer and portions of the polymer are selectively removed after exposure to ultraviolet light through a photographic mask. The remaining polymer does not react with the etchant used to dissolve the piezoceramic material. After removing the unnecessary piezoelectric ceramic (15), the remaining photosensitive polymer is removed.

The immersion time of the liquid to obtain a certain depth of chemical corrosion,
Determined by temperature, concentration, and mechanical stirring.

For example, the composition of the piezoelectric ceramic material is pbo.

7. When formed with a mixture of r02 + TiO2 + added impurities, the acid solution carrying out the chemical attack to form the independent parts of the piezoelectric ceramic material according to the invention is 10
fnl HCI (specific gravity 1.19), 3-HF (40
% solution) for about 3 hours at room temperature.

Another method for removing piezoelectric ceramic material is laser scribing, in which a continuous or pulsed laser is used to vaporize unwanted portions of the piezoelectric ceramic.

The piezoceramic transducer or laser is under the control of a mechanically preprogrammed microprocessor. Factors that influence the removal rate include laser power, atmosphere, laser focus concentration, exposure time, auxiliary gas, heat dissipation mechanism, fire resistance of the piezoelectric ceramic, effective dissipation of the piezoelectric ceramic, light absorption, etc. Care must be taken not to cause thermal stress to the piezoelectric ceramic near the removal part. As an example of using (16) laser scribing techniques in transducer arrays manufactured according to the present invention, (α
) Nd:YAG laser was used, (b) continuous wave mode and high frequency pulse (e.g. 5-10 KHz), (c) scanning speed 3 i7L/, . This technique was tested with and without an opening. (d) Single pass and multiple passes were used. Another technique for removing piezoceramic material is computer-controlled sand blasting. In this method, a stream of small particles, such as alumina, is ejected through a narrow nozzle together with high-pressure gas to grind the piezoelectric ceramic in a controlled manner. As with lasers, the cutting position is determined mechanically. As control parameters, exposure time, speed, particle density,
There is a collection of methods for particle types, separation distances, and particle flows.

Other techniques for removing transducer material include saw cutting,
Another technique in which a narrow silicon wafer cutting disk cuts out a portion of the piezoelectric ceramic is ultrasonic machining.

Saw cutting methods are usually limited to straight cuts. Ultrasonic machining uses a fine abrasive, such as a 600 grit boron carbide slurry. The tools used have the required pattern, for example, a circle, (17) rectangle, etc. The cutting tool uses a small amplitude and high frequency e.g.
It vibrates at 0000KHz. Cutting movement is precisely controlled,
The forces exerted on the workpiece are significantly smaller.

In this way, even extremely thin sheets of transducer material can be processed with gentle processing and close tolerances.

ADVANTAGEOUS EFFECTS OF THE INVENTION The method of manufacturing a transducer according to the present invention involves directly coating a sheet of transducer material with a diaphragm material and chemically or mechanically removing a portion of the transducer material to form a plurality of independent transducers. Form. This eliminates the known complicated manual work and allows uniform and accurate transducer arrays to be manufactured at low cost and in a short time.

[Brief explanation of the drawing]

1 is a cross-sectional view of a single sheet of transducer material adhered to an ink jet array; FIG. 2 is a cross-sectional view of a transducer array formed in accordance with the present invention; and FIG. 3 is a cross-sectional view of a transducer array formed in accordance with the invention. FIG. 4 is a cross-sectional view of a transducer array according to an embodiment of the present invention, FIG. 5 is a cross-sectional view showing an example of two layers of transducer material, and FIG. 6 is a transducer array. (18) 0 1: Transducer material 2: Diaphragm material 3: Transducer row
4: Ink 5: Ink chamber 6, 7, 9: Independent part 8: Transition part 10.11: Layer of opposite polarity 12: Remaining part (19)

Claims (1)

[Claims] 1. A method of manufacturing a transducer array for use in an impulse inkjet printhead from a single sheet of transducer material, comprising: a) coating the surface of the transducer material with 1i layers of diaphragm material; and b) removing a portion of the transducer material to leave a plurality of independent sections of transducer material extending from the diaphragm material. 2. The method of claim 1, wherein the diaphragm material is coated by an electrodeposition technique. 3. The method of claim 1, wherein the diaphragm is made of a material having a strength similar to that of the transducer material, and the diaphragm and transducer flex together upon expansion or contraction of the transducer. 4. The method of claim 1, wherein a sufficient amount of the transducer material is removed to form a plurality of discrete islands of transducer material. 5. The method of claim 1, wherein a sufficient amount of the transducer material is removed to form a plurality of independent sections without removing the entire thickness of the transducer material. 6. The method of claim 1, wherein said one sheet of transducer material is formed by bonding two sheets of transducer material of opposite polarity. 7. Said one sheet of transducer material has two transducer materials of opposite polarity.
3. The method of claim 2, wherein two sheets of transducer material are bonded together. 8. The method according to claim 1, wherein the removal step (b) is carried out by a chemical etching method. 9. The method according to claim 1, wherein the removing step (b) is performed by a laser scribing step. 10. The method according to claim 1, wherein the removal step (b) is carried out by sandblasting. 11. The method according to claim 1, wherein the removing step (b) is performed by ultrasonic processing. 12. 2. A method according to claim 1, wherein said removing step (b) is carried out by sawing. '13, claim 1, wherein the transducer material is polarized before the process (,).
The method described in section. 14. The method of claim 1, wherein the transducer material is a piezoceramic material. 15. The method of claim 1, wherein the diaphragm material is nickel. 16. The method of claim 2, wherein the diaphragm material is nickel. 17. The method of claim 15, wherein the transducer material is first coated with a layer of gold and nickel is electrodeposited onto the layer of gold. 18. A method of manufacturing an impulse ink jet printhead, comprising: a) coating a layer of diaphragm material on the face of a sheet of transducer material; and b) removing a required amount of said transducer material to form a diaphragm. A method of manufacturing an impulse inkjet printhead comprising: leaving a plurality of independent portions of transducer material extending from to form a transducer array, and C) securing said array to an inkjet array. 19. The method of claim 18, wherein the sheet of transducer material is sized to cover a majority of the ink chamber of an inkjet printhead. 20. Claim 18, wherein a sufficient amount of the transducer material is removed to form a plurality of independent islands of transducer material.
The method described in section. 21. The method of claim 18, wherein the diaphragm material is coated by electrodeposition. 22. The method of claim 18, wherein a sufficient amount of the transducer material is removed to form a plurality of independent sections of transducer material without removing the entire thickness of the material. 23. The method of claim 18, wherein the transducer material is a piezoceramic material. 24. The method of claim 18, wherein the transducer material is polarized before the step (,Z). 25. The method according to claim 18, wherein the step (b) is carried out by sandblasting. 26. The method according to claim 18, wherein the step (b) is performed by ultrasonic processing.