JPH03500029A - Drive element for recording head of ink printing device - 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] Driving element for a recording head of an ink printing device The present invention is based on the concept of the first aspect of the claim. The present invention relates to a recording head circumferential drive element J of an ink printing device.

A drive element of this type is known from DE-PS 2543.420. these The drive element includes a small cylindrical tube made of piezoelectric ceramic whose inner and outer walls have thin electrode layers; and an ink passage surrounded by a conversion element. Inside the conversion element, a metal Two spiral bodies are placed in the casting resin, and these spiral bodies are closely attached to the inner wall of the small tube as electrodes. are doing. The wall of the ink passage or ink chamber itself is made of cast resin. There is. Some of these drive elements, each with a conversion element assigned to it, are grouped together. A recording head is formed.

In the case of ink printing devices with multiple nozzles, the character quality is This is substantially determined by whether or not the discharge speed is high.

An important prerequisite for uniform ejection speed is the mechanical connection between the conversion element and the ink chamber. The bond must be stable. The transfer characteristics depend on the loads that occur during use of the device, i.e. Under loads such as temperature, frequency, and multiple alternating loads, It is not allowed to change over time.

In order to prevent fluctuations, in DE-PS2543420, the conversion element itself is injected into the wall of the ink chamber.

In addition, in the case of the drive element according to DE-0521, 64614, it is continuously polarized. A piezoelectric ceramic layer (piezoelectric platelets) is placed on a metal plate, and this metal plate , of the ink chamber! When the piezoelectric plate is excited, the inside of the ink chamber (pressure chamber) The recording nozzle ejects ink droplets. In this format, the conversion element is The useful piezoelectric plate is usually glued and fixed onto a metal plate.

However, this type of adhesive bonding also includes bonding to smooth surfaces. Since various material and surface effects occur, this type of joining is not always suitable for Not stable enough.

It is also known from EP-A-0103841 as follows. sand That is, the ink head piezoelectric tube, which serves as a transducer, is installed inside the wall of the ink chamber. The tube is cast so that the tube surrounds one side of the tube. By doing this, the conversion element centering is improved.

Furthermore, EP-A-0150348 describes a block in which a plurality of piezoelectric platelets are juxtaposed. A recording head for an ink printing device is described. Check the degree of nozzle opening. To ensure this, the outer cover of the block has a snout on one side. these One side of the protrusion extends into the piezoelectric plate.

The object of the invention is therefore to provide a drive element for a recording head of the type described in the above. to ensure that its transport characteristics do not change during use, and in particular to The purpose is to ensure that the connection with the wall is sufficiently stable.

This problem is solved in the case of a drive element of the type mentioned at the outset, It was solved by means of having.

Advantageous embodiments of the invention have the features described in the subclaims.

The conversion element and the ink chamber wall are engaged with each other and joined by shape connection. By the ink chamber! The parts and conversion elements are subjected to loads due to temperature, vibration frequency, and multiple alternating loads. forms an unrelated unit, and the transport characteristics of this unit are will not change. Conversion element and ink chamber! It is possible for the parts to gradually dissociate. No.

In an advantageous embodiment of the invention, the ink chamber wall is at least partially hardenable. material and/or adhesive material, and the transducer element is surrounded by this material. There is. The conversion element itself preferably has a cutout with a conical cross section, these The material flows into the cutout, creating a perfect form-locking bond between the ink chamber wall and the conversion element. care is taken to ensure that this occurs. Depending on the configuration of the ink chamber, the material can be used as a converter element. For example, if the ink chamber is configured as a small tube and is to be viewed within the ink chamber wall, then the Resin can be used. Alternatively, the ° conversion element may consist of piezoelectric platelets; If the piezoelectric plates are to be glued to one side of the ink chamber side wall, the material must be hardened Use plastic where possible.

In the case of a particularly advantageous embodiment of the invention in which the transducer element is configured as a piezoelectric tube, the detent A wire electrode, for example a helical wire, in which the material or shaped part contacts the inside of the piezoelectric tube It consists of This helical wire is brazed in a form-fitting manner to the piezoelectric tube, making the connection will be combined. Brazing occurs when material from the ink chamber wall flows into the grooves that occur in the area. This achieves a form-locking connection between the ink chamber wall (casting resin) and the piezoelectric tube. be done.

With such a form-locking interlocking joint, it is possible in all cases to: Become. That is, for example, adhesive force, negative pressure, swelling force, and the relationship between the conversion element and the ink chamber wall. A constant preload is generated by adjusting the balance of the double-edged blades, such as the contractile force that acts on the separation surface. This makes it possible to prevent the element from disassociating or loosening during use. Ru.

By forming holes or slits by ultra-short wave or laser processing, In addition, the filling behavior during casting is improved and the conversion elements introduced during hardening of the casting are improved. The internal stress around the child is reduced.

The economical production of perforated piezoelectric transducers, whether piezoplatelets or piezotubules, Yes, this is possible through ultrasonic or laser processing. In both cases, the piezoelectric sensor The electrical and mechanical properties of ramic are maintained even after processing. When drilling with laser The resulting conical shape can be used for locking fixation by form-locking.

Next, embodiments of the present invention will be explained in detail with reference to the drawings.

Figure 1 shows the drive for the recording head of an ink printing device that has a piezoelectric tube as a conversion element. A suggested cross-sectional view of the element, FIG. 2, shows an ink printing device with piezoelectric platelets as transducer elements. FIG. 3 is an implied cross-sectional view of the recording head drive element of FIG. 3, which is configured as a metal lock; A perspective view of a piezoelectric tube with brazed internal electrodes, t$4 shows a metal lock body and FIG. 4 is a suggested cross-sectional view of a junction point with a conversion element;

Ink printer recording heads, such as D The device described in E-O32543451 has a large number of drive elements 12. child These drive elements are caused to operate according to the symbol, eject ink in a suitable manner, Generate a symbol on the record carrier. The drive element 12 is integrally formed by a casting method. It is cast in a recording head made of cast resin. The recording head has many ink passages. These passages are surrounded by a conversion element 10. Conversion element 1 0 consists in this case of polarized piezoceramic tubules, these tubules has thin metal layers on the inner and outer walls 11 that serve as electrodes. each inn The wall of the ink chamber 14 (ink chamber wall 15) is made of a single layer of head material (casting resin). is formed. When manufacturing the recording head, the inner electrode consisting of the metal lock 16 is It is disposed within the tank chamber wall 15. This inner electrode is part of the conversion element 1.0! connected to ll touch At that time, the metal lock body 16 is coated with a silver layer 32, as can be seen from FIG. Consists of metal helical windings with

Piezoelectric tube (conversion element 10) and ink chamber! ! Achieving a bond by form connection between 15 and Therefore, in the embodiments of FIGS. 1 and 2, the conversion element IO has a conical through hole 1. 7. These conical through holes 17 are converted using a laser drilling machine. Formed before implanting device 10. The conversion element 10 first performs necessary electrical and mechanical Balanced according to mechanical property values. These characteristic values vary due to laser processing. There's nothing to do.

When casting the conversion element 10 during the production of a recording head, the conversion element 10 is first molded with a mandrel or is inserted into a similar molding part and then placed into a corresponding mold. pour into mold The poured resin enters the hole 17. At that time, the holes and holes 17 are particularly made of casting resin. During curing of the transducer, it is inserted to compensate for internal stresses occurring around the transducer element.

In the embodiment of FIGS. 3 and 4, the metal lock 16 serves as the inner electrode and the filter It is combined with the piezoelectric tube by mounting. Brazing is difficult due to grooves 33 created in the area. Form connection between the ink chamber wall 15 made of stomach fat and the conversion element 10 (piezoelectric tube) A combination occurs.

It is also conceivable to use other molded members instead of the metal lock body 16. parable For example, a circular pressure-shaped molded part with an undercut part is provided on the inner wall of the conversion element. You may. The important point is to make sure that the conversion element and the ink chamber wall are engaged with each other. , so that a perfect form-fitting connection occurs between the two.

When manufacturing a recording head by casting, first the inner electrode is covered with a silver layer 32. A metal locking body 16, which serves as a It is additionally soldered. This is possible, for example, by doing . In other words, as a result of the internal stress, the wax that is attached to the inside of the piezoelectric tube is The metal lock body 16 is heated by passing a strong current through it for a short period of time. be. By doing this, the wax melts at the point of contact between the piezoelectric tube and the lock body. It will be done. However, wave soldering or other types of soldering are also possible. It is.

The transducer element brought into contact in this way is then inserted into a mandrel or similar shaped part. and place it in the appropriate mold. The resin injected into the mold is treated as a metal lock body 16. It surrounds 33.

During and after curing of the casting resin, as shown in Figure 1, the conversion element and the ink chamber! A force is generated consisting of a component force acting in one angular direction on the separation plane. Component force 1 shown 8 is the adhesive force between the ink chamber wall and the conversion element, and the component force 19 is the small amount of ink. Component force 20 is the swelling force during manufacturing, and component force 21 is the force generated by static negative pressure. This is the shrinkage force that occurs when the casting resin hardens.

The tensile and compressive stresses occurring during use of the drive element are indicated by the symbol 22.

All forces shown are with respect to the separation plane between the ink chamber wall 15 and the transducer element 10. It is something that occurs.

As can be seen from Figure 1, the main force component is the ink chamber wall that is exposed to the initial stress after curing. This serves to ensure a reliable form-fitting connection between the portion 15 and the conversion element 10.

As a result, the working force (tensile stress and compressive stress 22) that depends on the function is reduced to the ink chamber. Dissociation of the separation plane between wall 15 and conversion element 10 cannot occur. comparatively No loss occurs even during long-term use. The conversion element 10 is connected to the ink chamber 14. directly affects the system. This ensures pulse-true control behavior.

The embodiment of the drive element shown in FIG. This is a driving element used in inch-structure ink print heads. This driving element is circular It has a cylindrical pressure chamber 23 (ink chamber), and this pressure chamber is installed inside the pressure chamber plate 24. I'm being kicked. Ink is supplied to the pressure chamber 23 via an ink supply passage 26. On the other side of the cross section of the pressure chamber 23, on the side opposite to the ink supply passage inlet area, there is a nozzle. The nozzles 28 of the individual drive elements in which the nozzle passages 27 are arranged are connected to a common nozzle plate. 29. The pressure chamber 23 is covered by a thin diaphragm plate 30. The diaphragm plate 30 includes a circular piezoelectric ceramic small transducer element. They are arranged in the form of a plate 31. Similar to the embodiment shown in Figure 1, this piezoelectric ceramic The small plate (conversion element 31) also has a conical hole 17 made by laser or ultrasound. have. These holes 17 are inserted into the piezoceramic platelet 31 before the piezoceramic platelet 31 is installed. Make it to 1. The small plate 31 and the diaphragm plate 30 form an ink chamber, that is, a pressure They form the actual walls of the chamber 23 and are joined together by adhesive. glue in that case penetrates the conical hole 17 and produces a form-fitting bond after hardening.

The force balance that occurs after curing or during operation of the drive element is, in principle, shown in FIG. match something.

I.G.I. IG 2 international search report

Claims (1)

[Claims] 1. Piezoelectric transducer arranged on one wall (15, 30) of the ink chamber (14, 23) (10, 31) in the recording head drive element (12) of the ink printing device Then, the conversion element (10, 31) and the ink chamber wall (15, 30) are in contact with each other. characterized in that they are interconnected in a form-connected manner in which they interlock with each other along the Drive element for recording head of ink printing device 2. The ink chamber wall (15) is both partially made of a curable material (13) and/or an adhesive material (25) and the transducing element (10, 31) receives the material (13, 25). The recording head of an ink printing device according to claim 1, characterized in that it has a hole (17). Drive element for the board. 3. The ink chamber wall (15) has a diaphragm layer (30) and also has a conversion element. (31) is fixed to the diaphragm layer (30) via the material (25) The drive element according to claim 1 or 2, characterized in that: 4. The conversion element (10) is a piezoelectric ceramic formed within the ink chamber wall (15). 3. The driving element according to claim 2, characterized in that it comprises a small tube. 5. It is characterized in that the bore (17) is configured as a through bore with a conical cross section. The driving element according to any one of claims 1 to 4, characterized in that: 6. The through hole is formed in the conversion element (10) by ultrasonic or laser treatment. The drive according to any one of claims 1 to 5, characterized in that the drive is formed by: element. 7. The conversion element (10) is placed on the side facing the ink chamber wall (15). ) to the ink chamber wall (15). 2. The driving element according to claim 1, wherein the driving element has the following characteristics. 8. When configuring the conversion element (10) as a piezoelectric tube, the molded member is a piezoelectric tube (10). The wire electrode (16) is configured as a wire electrode (16) that contacts the inside of the wire electrode (16). 6) are joined by, for example, gluing, brazing, or welding. The driving element according to claim 1 or 7.