KR880000403B1 - Piezoelectric ceramic transducer - Google Patents

Abstract

Electroacoustic transducer for a microphone or loudspeaker includes electrodes formed on both main surfaces of a piezoelectric ceramic plate with curved surfaces and held by a frame of organic high- polymer resin, and circuitry for applying an electrical signal to the electrodes. The plate is pref. of transparent ceramic, and the frame is a flat plate with an opening or recess in the centre. The arrangement is suitable for wide frequency band audio signals. The ceramic plate radius of curvature is pref. 150-400 mm.

Description

Piezoelectric Ceramic Transducer

1 and 2 are schematic diagrams for explaining the conventional transducer.

3 is a schematic diagram for explaining the transduder of the present invention.

Figures 4a to 4e is a diagram of various methods of attachment of the piezoelectric ceramic face plate.

5a to 5c are frequency characteristic diagrams of various transducers.

6a to 6b are a plan view and a cross-sectional view of a transducer each showing an embodiment of the present invention.

7 is a cross-sectional view of another embodiment.

8 and 9 are perspective views of another embodiment.

10 is a plan view of a piezoelectric ceramic plate with an electrode attached thereto.

11 to 13 are explanatory diagrams showing a method of forming a curved surface.

14 is an explanatory diagram showing another embodiment of the present invention.

15 is a cross-sectional view for explaining the manufacturing process thereof.

The present invention relates to a plate-shaped transduder using a thin plate of a piezoelectric body. Useful for audio microphones or speakers.

In recent years, technologies for miniaturizing radios, tape recorders, and the like and for a long time by battery driving have been advanced, and molds that can be put in thin pockets have become popular. This trend is largely driven by the technology of circuit integration that has led to the spread of pocket-type electronic desk calculators. In addition, the electronic desk calculator is equipped with a small sounding body developed for the alarm of the watch, so that the input and output of the calculation not only displays to the eye but also audio signal to the ear.

Electronic micro-devices such as battery-powered clocks, calculators, radios, tape recorders, and the like tend to have a speaker and / or a microphone. In this case, the display has progressed in miniaturization, flat panel, and low power consumption due to the appearance of liquid crystal, but the speaker is not completely satisfied with the compact, thin, and low power. Therefore, the demand for the development of flat-panel speakers has risen sharply, becoming a technological task of the times.

As described above, the sounding body required for the electronic micro device should be small, flat, and small power. Piezoelectric buzzers are excellent in terms of small size, flat plate and small power. As a resonator for a signal of a constant frequency and a speaker for an audio signal having a wide frequency band, it could not cover a desired sound band and had a difficult difficulty in making clear speech.

As an example of a piezoelectric buzzer for a watch, Japanese Patent Laid-Open No. 1978-55171 or the like is known, for example.

The present invention provides a piezoelectric ceramic plate having a curved surface, an electrode formed on both main surfaces of the piezoelectric ceramic plate, a frame for holding the piezoelectric ceramic plate, and a transducer having at least a means for applying an electrical signal to the electrode. In this case, the holding frame is formed of an organic polymer resin. Since the piezoelectric ceramic plate has a curved surface and the holding frame is made of an organic polymer resin or the like, it is very suitable for use as a speaker for audio with a wide frequency band.

In a conventional piezoelectric ceramic transducer using a piezoelectric body having electrodes attached to both main surfaces, an AC signal is applied to the flat plate, and vibration occurs in the flat surface of the flat plate due to the piezoelectric effect. This vibration is not preferable as the sound output to vibrate the air because the vibration of the mode that the surface is enlarged or reduced.

In order to obtain a sound output by vibrating the flat plate, the flat plate must excite the vibration of the bending mode in which the plane itself moves in the normal direction of the face.

In general, the bending mode cannot be excited only by applying an AC signal to the flat plate, but the bimorph structure can easily excite the bending mode. However, the bimorph is a structure in which two flat plates are applied together, and as a result, the bending motion occurs as a result of being constrained to the other plate through the surface of the expansion and contraction of one plate. Therefore, during the bending exercise, the stress is always applied to the fit surface, this stress can be said to be the driving force of the bending exercise.

As is apparent from the above-described principle of the bending motion in the bimorph resonator, the piezoelectric plate can no longer be freely deformed, but can only be deformed in terms of fitting. For this reason, the conversion efficiency converted from the electrical input to the mechanical vibration becomes half that of free deformation.

However, in the present invention, since the curved surface is provided by fitting the piezoelectric thin film to the holding plate as described above, it is possible to provide a vibrator capable of converting the in-plane stretching and contraction of the piezoelectric body into a bending motion in a form close to free deformation.

In addition, the above-mentioned fats and oils are formed of synthetic resin, and such a work is a preferable configuration for sound. The curvature of a curvature is made into about 100-1000 mm, and about 150-400 mm is especially preferable.

According to the present invention, the flat plate of the piezoelectric body is bent in advance, and the periphery of the plate is fixed to maintain the curved state stably. Since both main surfaces of the piezoelectric flat plate are in a free state, when a voltage is applied to the electrodes, they stretch freely but are fixed so as not to change the size of the periphery of the plate, so that bending motion occurs. When the plate is stretched, the curvature becomes larger and the radius of curvature of the curve becomes smaller, and when the plate shrinks, the radius of curvature becomes larger. At this time, the difference in curvature radius on both sides becomes larger as the curvature becomes larger, and as the plate thickness becomes thicker. When bending vibration occurs due to the application of an electrical signal, the energy conversion efficiency decreases in response to the difference in the amount of change in the radius of curvature of both sides of the plate. The thinner the platen thickness of the piezoelectric body is, the higher the conversion efficiency is. The smaller the amplitude of vibration is, the higher the conversion efficiency becomes.

The above-described principle is the principle of the operating mechanism as a speaker of the piezoelectric transducer according to the present invention, and it has been found that the higher the electro-mechanical energy-conversion efficiency is in the case of a thin plate. However, in the case of the speaker, the sound output is determined by the vibration area and amplitude since the vibration is applied to the air, and the mechanical impedance such as the rigidity of the diaphragm is not a problem.

On the other hand, due to the necessity of converting the sound pressure generated by the bare air vibration of the microphone into an electric signal, the diaphragm must have a low mechanical impedance so that it can sufficiently respond to the vibration of the air. If the transducer acts as a bend mode, it must be thin and bent to become a diaphragm. The thinner the transduder of the present invention, the higher the conversion efficiency is. Therefore, it is very convenient to use it as a microphone.

In addition, the transducer of the present invention has a feature that can be used with high efficiency in practical use. When using a transduder as a speaker or as a microphone, the oscillator must be maintained in any way.

It is common for the flexor mode to remain at the perimeter of the oscillator. In the conventional bimorph type, it is common to sandwich and reinforce a metal thin plate on a neutral surface, and in a unimorph type, it is common to apply a piezoelectric plate to a metal diaphragm. The bimorph oscillator is held by a so-called "peripheral fixation" holding method (FIG. 1) which fixes the periphery of the metal plate to a frame or the like. Peripheral support method (Figure 2) is more efficient to maintain the guiding force of the curved mode, but it is difficult to maintain the peripheral support method in practice. Therefore, the metal plate is made larger than the piezoelectric plate and the periphery is fixed. The efficiency is even lower than the theoretical value.

On the other hand, since the piezoelectric vibrator is kept curved in a small frame, the transduder of the present invention adopts a peripheral support method, as shown in FIG. 3, and is easy to obtain conversion efficiency close to the theoretical value. It is also one of the great features.

By applying the present invention to a transparent flat panel speaker as described above, it is possible to secure a practically sufficient sound and to make it clear. That is, this transparent flat panel speaker has the following advantages. (1) Since both the vibrating body and the sound generating face plate are provided, it is unnecessary to apply the vibrating body to the generating face plate. For this reason, the fall of the transparency by an adhesive agent can be prevented. In addition, shortening of the life due to deterioration of the adhesive over time does not occur. (2) Generally, the protective cover is removed from the transduder so that it can be installed independently, thereby lowering the mechanical impedance. In addition, the bass characteristics can be improved. (3) As well as a speaker, it can also be used as a microphone.

In this way, the transparent speaker can be a significant advantage. That is, the conventional transparent flat sounding body mainly consists of a transparent ceramic, and the structure is a thing which only widened the conventional bimorph buzzer, but expands the practical range further.

4A to 4E and 5A to 5C respectively show various holding methods of piezoelectric ceramic plates and trends in the frequency characteristics of the voices.

4A shows the piezoelectric vibrator 2 bonded to the face plate 1. The piezoelectric vibrator 2 has electrodes on both main surfaces, but is omitted in the drawing. In this case, together with the piezoelectric vibrator 2, the face plate 1 also vibrates to sound, but the frequency band of the voice volume is narrow as illustrated in FIG. 5A. The voice volume is also small. Such a structure is generally used only in a buzzer, and it is difficult to pronounce a voice such as fostering.

4b attaches the transducer of FIG. 4a to the frame 3 with the opening 8. Since the face plate 1 vibrates with the contact portion between the frame 3 and the face plate 1 being knotted, the voice volume increases, but the frequency band does not change in comparison with the above-described example.

4C shows the curved piezoelectric ceramic face plate 5 fitted at the tip of the metal frame 4. Since the face plate 5 is fixed to an inelastic material such as metal, the face plate 5 vibrates very largely in the direction perpendicular to the face.

However, the frequency band is very narrow as shown in FIG. 5C.

4D is a fitting of the curved piezoceramic face plate 5 to the metal frame 6 which can be microvariably. Since the metal frame 6 is also finely moved together with the face plate 5, the frequency band is slightly larger as shown in FIG. 5E, but is insufficient to pronounce the voice.

Figure 4e shows the configuration of the present invention. The curved piezoelectric ceramic face plate 5 is fitted to the organic polymer resin frame 7. (The face plate may be adhesively bonded to the frame 7 only by the end portion.) At the time of fixing, the face plate 5 is capable of amplitude movement in the vertical direction and flexion movement in the horizontal direction of the face. The organic polymer resin has a stiffness of 0.1 × 10 ⁵ to 0.5 × 10 ⁵ Nm / kg or less (where N is Newton's constant) and generally has a single digit value compared to a general metal. In other words, they testify about mechanical strength and have the organic function of the faceplate, and they are rich in elasticity. 5e shows a frequency band. A flat frequency band was obtained over 0.1-5KHz, which was sufficient for speech pronunciation.

Example 1

6A and 6B are schematic plan views and cross-sectional views, respectively, of a transduder as an embodiment of the present invention.

A piezoelectric power plate having a diameter of 27 mm and a thickness of 0.2 mm made of Pb (ZrTi) O ₃ -based transparent piezoelectric ceramic was prepared. The transparent electrodes 12 are coated on both main surfaces of the transparent piezoelectric ceramic original plate 11, and polarization treatment for applying a DC high voltage is performed by using the electrodes. A 150 mm square, 1.5 mm thick polycarbonate transparent plate 15 is prepared, a hole 14 having a diameter of 26.95 mm is drilled in the center thereof, and a transparent ceramic disc is formed in the hole 14. (11) is inserted and maintained in a curved surface state in which the radius of curvature R becomes 200 to 150 mm.

Transparent films 16 and 17 are coated on both sides of the front and back sides of the polycarbonate square plate instead of the lead wires, and connected to the terminals 18 and 19, respectively. . The silver paste 13 is applied to the ends of the transparent lead wires 16 and 17 to the holes 14 to electrically couple the electrodes 12 of the transparent piezoelectric plate 11 to each other. The transducer produced in this way can radiate abundant volume as a speaker when an audio signal is applied to the terminals 18 and 19.

An advantage of this embodiment is that the transparent flat panel speaker is realized, but another advantage lies in the function of the vibrator of the sounding unit. That is, since the holding plate 15 of the polycarbonate holds the diaphragm 11 in a curved state, the periphery of the hole 14 is deformed with considerable compressive force. For this reason, when the diaphragm 11 vibrates and curves, the holding plate 15 also vibrates as a reaction, and sound also comes out on the surface of the holding plate. This is an advantage of the present embodiment, and the sound of the high frequency component is generated from the diaphragm 11, and the sound of the low frequency component is generated in the holding plate 15 portion. As a function of the speaker, the diaphragm 11 part acts as a high loudness loudspeaker, and the part of the holding plate 15 functions as a low loudness loudspeaker. As a result, it was confirmed that the frequency response of the output was wideband and ranged from 50 Hz to 10 KHz or more. This is a good result that a flatbed speaker could not.

In the above example, although polycarbonate was used as fats and oils 15, it is not limited to this, Other organic polymers and resin can also be used. For example, a wide range of materials can be used, such as foaming resins such as acrylic or foamed polystyrene, hard vinyl crawlide, phenol-protected aldehyde resins. In addition, phosphor bronze, stainless steal, duralumin and the like could also be used.

Although the above embodiment relates to a transducer unit, reference is also made to the characteristic case in relation to the use.

Example 2

7 is a schematic cross-sectional view of a transduder to another embodiment of the present invention.

, 내경 26.95㎜

두께 1.5㎜의 링상의 틀(25)로 되어 있다. 진동자(21)는 링(25)안에 R=200~150㎜의 만곡면을 이루도록 유지되어 있고, 그 투명전극면(22)에는 스프링(26), (27)이 접하고 있다. 링(25)은 손목시계의 금속 케이스(20)에 장치되며, 그 위에 투명보호판(23)을 붙인 스테일레스링(24)을 고정시킨다. 스프링(26)은 스테인레스링(24)을 통해서 케이스(20)에 접지되어 있다. 스프링(27)은 절환스위치를 통해서 증폭기의 입력단자와, 음성합성회로의 출력에 이어져 있다. 음성합성회로의 출력을 작동하면 진동자(21)는 차임의 소리를 내거나 현재의 시각을 "몇시 몇분 입니다"라고 짧은 음성으로 알리거나 한다. 절환스위치를 증폭기로 바꾸면, 트랜스듀우서는 마이크로폰으로 바뀌며, 와이어레스 마이크로서 동작하는 것이 확인되었다. 투명트랜스듀우서는 표시부의 창문을 겸하므로, 점유공간이 적어 소형기기에 편리하다.The vibrator 21 as used in Example 1 is mounted on the same polycarbonate as in Example 1, but in this embodiment, the polycarbonate is not a plate, and as shown in Fig. 7, the outer diameter is 33 mm.

Internal diameter 26.95 mm

A ring-shaped mold 25 having a thickness of 1.5 mm is used. The vibrator 21 is held in the ring 25 to form a curved surface of R = 200 to 150 mm, and springs 26 and 27 are in contact with the transparent electrode surface 22. The ring 25 is mounted on the metal case 20 of the watch and fixes the stainless ring 24 attached with the transparent protective plate 23 thereon. The spring 26 is grounded to the case 20 via the stainless ring 24. The spring 27 is connected to the input terminal of the amplifier and the output of the voice synthesis circuit through a switching switch. When the output of the voice synthesis circuit is activated, the vibrator 21 makes a chime or announces the current time in a short voice, "What time and minute it is." When the changeover switch was changed to an amplifier, the transducer was turned into a microphone and it was confirmed that it was operating as a wireless microphone. The transparent transduder also serves as a window for the display, so it has a small footprint and is convenient for small devices.

Example 3

8 is a schematic perspective view of a transduder as another embodiment of the present invention.

A Pb (ZrTi) O ₃ -based transparent ceramic plate is molded into a spherical plate 31 having a thickness of 20 mm x 40 mm and a thickness of 0.2 mm, coated with a transparent electrode, and polarized to form a piezoelectric plate. This is curved to form a curvature radius of 200 to 150 mm, and is held in place by a polycarbonate plate 35 having a thickness of 100 mm x 70 mm and a thickness of 1.5 mm. The polycarbonate plate 35 described above is fixed to a box 36 of 100 mm × 70 mm × 15 mm size made of polygacarbonate prepared separately. Audio devices such as radios and tape recorders can be accommodated inside the box. When the input is applied to the transparent electrode, the vibrator 31 acts as a speaker, but the box 36 acts as a resonance box. Because it works, a very loud volume was obtained

Example 4

7 is a schematic perspective view of a transduder as another embodiment of the present invention.

, 두께 0.2㎜의 Pb(ZrTi)O₃계 세라믹 원판의 양 주면에 은전극(42)이 부착된 세라믹 압전 진동자(41)를, 실시예 5의 경우와 마찬가지로 외경50㎜, 내경 39.90㎜, 두께 2㎜의 폴리카아보네이트 링(45)에 끼워넣고, 세라믹 압전진동자를 R=200~150㎜의 곡률반경을 갖는 만곡면상으로 유지한다. 두께 0.5㎜이고 외경이 40㎜

의 금속제 0링(43)을 사용하여진동판(41)을 고정시킨다. 0링(43)은 각기 진동자(41)의 전극(42)과 전기적으로 접속시키고 있으므로. 0링(43)에 리이드선을 납땜하여, 타단을 링(5)과 접착한 원통(46)의 밀판에 고정시킨 단자(47) 및 (48)과 접속한다.40mm in diameter

A ceramic piezoelectric vibrator 41 having silver electrodes 42 attached to both main surfaces of a 0.2 mm thick Pb (ZrTi) O ₃ -based ceramic disc, as in Example 5, had an outer diameter of 50 mm, an inner diameter of 39.90 mm, and a thickness of It fits in the polycarbonate ring 45 of 2 mm, and keeps a ceramic piezoelectric vibrator on the curved surface which has a radius of curvature of R = 200-150 mm. 0.5mm thick and 40mm outer diameter

The vibration plate 41 is fixed by using a metal 0 ring 43. Since the 0 ring 43 is electrically connected to the electrode 42 of the vibrator 41, respectively. The lead wire is soldered to the zero ring 43, and the other end is connected to the terminals 47 and 48 fixed to the tight plates of the cylinder 46 adhered to the ring 5.

This is a transducer for open spaces, which is placed in a case such as a headphone or a handset of a telephone, and when the terminals 47 and 48 are connected to a predetermined circuit, a transdue suitable for each purpose is used. It becomes Uther. When used in headphones, earpieces, or the like, the opening of the transducer case is blocked by the ear, so that the vibrator can easily match the acoustic impedance, and both the sensitivity and the sound quality are good. When used as a headphone, when a 1.5 volt signal is applied, enough sound is heard in the ear. When used as a transmitter, it is in a half-open space, which increases sensitivity and protects against external noise. However, the transducer must be sufficiently damped from the case and stored.

Although the transduder of the present invention has been described above based on the examples, it can be used in a transmitter or receiver and can be configured to be ultra-thin, and there are basic advantages such as simple structure and high electric / acoustic conversion efficiency.

Example 5

The requirement of this kind of transduder is to keep the piezoelectric ceramic thin plates on a curved surface. The curved surface is a spherical shape, which is pressed by using a ceramic plate at room temperature or high temperature, and then fixed with an adhesive to leave a curved strain on the ceramic. Can be. At this time, the shape of the ceramic plate may be any shape such as circle, ellipse, square, sphere, polygon. Lead wires are connected to electrodes on both front and back surfaces of the curved piezoelectric ceramic, and an audio electric signal is applied. Since only the curvature of the piezoelectric ceramic plate can be fixed, the periphery of the ceramic plate can be fixed by the adhesive, so that a vibrational movement in the vertical direction occurs on the surface, thereby making it an audio transducer.

It is important to fix the curved deformed piezoelectric ceramic transducer to a mold having a slightly smaller size and having a shape that is roughly similar to its appearance. Since the opening is slightly smaller than the ceramic, the periphery of the ceramic can be placed in the mold with the same hole protruding from it. For this reason, there is an advantage that can easily fix the periphery of the ceramic plate with a mold and an adhesive. Since the ceramic made by this method is fixed to the mold, the curved deformation can be kept stable and permanently at all times. Moreover, when the audio signal is applied, the outer diameter of the ceramic is hardly changed to the pore diameter of the mold, which is great. As a result of the greater bending vibration than the freely curved curved plate, the radiation volume of the transducer increases.

This is not limited to loudspeakers, even if you use a transducer as a microphone to convert sound into an electrical signal. Therefore, hereinafter, the description of the transducer will be described mainly for the speaker for simplicity.

An audio signal is applied to the vertical mixing plate, and the plate expands and contracts, and the outer periphery is also changed, but is fixed to the frame as described above. If the size of the template is selected sufficiently larger than that of the ceramic, the template has a sufficiently good response to low frequency signals. In other words, if the curved piezoelectric ceramic plate is fixed to a mold plate with a sufficiently large area, a transduder having a low sound response can be formed, thereby improving sound quality. In other words, the holding plate may be mechanically sufficiently sufficiently held, while the holding plate may be made large enough to improve sound characteristics.

Here, it is not a simple matter of bending the ceramic plate to make residual strain with high accuracy. That is, it requires a high degree of jig. If the radius of curvature of the deformation is large, no deformation is left. If the radius of curvature is small, the deformation is easy to be broken, but is easily broken. Moreover, rather than being too deformed to break even if the radius of curvature is too small, the transduer side, which maintains a stable shape so that the curvature radius is barely curved, has high electro-acoustic change efficiency. For this reason, it is preferable to deform the ceramic thin plate slightly and surely.

As a specific means for realizing this, for example, a frame plate with a hole slightly smaller than the appearance of ceramics is placed on a spherical steel stand. A heavy ring having a concave concave surface of the iron surface is also placed as a bell from above the frame. The frame is deformed into the steel surface and the size of the hole is enlarged. In this enlarged state, the upper surface around the hole and the lower surface of the ceramic are bonded. When the adhesive is cured, the mold is peeled off from the iron stand quietly, and the flattening is made flat, so that the ceramic sheet is brought into the adhesive surface and the iron sheet deformation is easily obtained. It demonstrates concretely next.

The piezoelectric ceramic transducer on the steel plate uses a piezoelectric ceramic represented by Pb (ZrTi) O ₃ based ceramic or a transparent piezoelectric ceramic 51 represented by Pb _1-x Lax (Zr _1-y Ti _y ) ₁ -T1 O ₃ . As a raw material, a thin and flat ceramic thin plate having a thickness of about 0.1 to 0.5 mm, an area of about 200 to 10,000 mm 2, and an area-to-thickness ratio of about 2,000 to 20.000 mm is produced. The top view is shown in FIG. The shape of the thin plate is arbitrary depending on the purpose, such as circles, rudders, squares, spheres, polygons, and the like. The method of silver thin film is formed on both main surfaces of the thin plate 51 by thermocompression bonding, metal deposition, sputtering, plating, spraying, and coating. The electrode 52 is attached. Depending on the purpose, the electrode can be applied in various ways, such as in a state without shine such as silver hot pressing, in a state in which a metallic light is formed like a plating film, or in a transparent electrode film of In ₂ O ₃ -SnO ₂ . It is preferable that only a thin electrode is firmly attached, and it is more convenient to have the part 55 which can directly solder the lead wires 54 and 54 '.

Next, a polarization treatment is performed by applying a direct current high voltage between the electrodes of the front and back plates. Although the piezoelectricity is generated by this polarization treatment, the processing conditions are unique to each material, and according to the inherent optimum conditions, generally, 20 to 40 KV / in a high-temperature atmosphere (sometimes using insulating oil) of about 80 ° C. Apply a DC high voltage of 30 cm or more. The polarized piezoceramic flat plate is adhesively fixed to a predetermined holding plate to give a curved deformation on a spherical surface to obtain a transducer.

Another method of forming the curved surface will be described next.

As shown in FIG. 11, the polarized piezoceramic thin plate 61 is sandwiched between the concave jig 66 with the same curvature as the spherical jig 65 of the concave surface having a radius of curvature of about 400 mm, Give a variation. 62 is an electrode provided on the piezoelectric ceramic plate, and 67 and 67 'are wirings. If the radius of curvature is large, no deformation is left, and if the radius is small, the ceramic is easily broken. In order to obtain stable deformation, it is effective to press at a high temperature. In this case, the ceramic plate to be used is formed by the above-mentioned method, and the electrode before polarization is used. After polarization, the polarization is eliminated when hot pressed, and repolarization is required.

The spherical jig as mentioned above was made using stainless steel, and the ceramic plate with an electrode was sandwiched and heated above the Curie temperature of a raw material. Hold the material briefly above the Curie temperature and allow it to cool slowly. When the temperature of the material was lower than 100 ° C., when it was gradually cooled while applying a DC electric field having a strength of about 20 to 40 KV / cm between the electrodes, the curvature deformation and polarization treatment could be performed.

Example 6

The same effect can be obtained by using a ceramic having a large warping effect. Next, it demonstrates based on FIG.

의 원판소자(61)를 만들었다. 전왜소자는 분극처리를 할 필요가 없으므로, 실시예 5와 같은 방법으로 50㎜, 두께 1.5㎜, 동심원상으로 직경 25㎜의 구멍이 뚫린 폴린카아보네이트판의 도우너트상 링(63)에 에폭시계 접착제로 단단하게 접착했다. 이때 링은 제12도에 나타낸 철구면(凸球面) 지그(65)와 요구면 변형 링지그(66) 사이에 끼워넣어 내경 25㎜의 구멍이 확대된 상태에서 전왜소자(61)를 접착 고정한 것이다. 따라서, 요구면 지그를 제외하고, 철판 변형하고 있었던 폴리카아보네이트 링(63)이 평판으로 되돌아가는것과 동시에 전왜세라밀(61)은 철면 변형이 발생하여, 음향 트랜스듀우서가 만들어졌다. 제13도는 이 상태를 나타낸 단면도이다. 양주면의 전극(62)에 리이드선(69)(69')를 납땜하여 리이드선(69)을 전원(70)에, (69')를 부하저항(71)에 접속했다.Pb (Mg 1/3 Nb 2/3) O ₃ -PbTiO ₃ -based ceramic was used here, and the formation was the same as that of the device of Example 5, and the electrode 62 was similarly implemented to have a thickness of 0.1 mm and a diameter of 30 mm.

The original element 61 was made. Since the pre-distortion element does not need to be polarized, epoxy is applied to the donut-like ring 63 of a polycarbonate plate having a diameter of 50 mm, a thickness of 1.5 mm, and a concentric circle of 25 mm in the same manner as in Example 5. It adhere | attached firmly with the system adhesive. At this time, the ring is sandwiched between the steel ball surface jig 65 and the required surface deformation ring jig 66 shown in FIG. 12, and the predistortion element 61 is adhesively fixed in the state where the hole having an inner diameter of 25 mm is enlarged. . Therefore, except for the required surface jig, the polycarbonate ring 63, which had been deformed on the iron plate, returned to the flat plate, and at the same time, the warped ceramics 61 had a deformed iron surface, whereby an acoustic transducer was produced. 13 is a cross-sectional view showing this state. Lead wires 69 and 69 'were soldered to electrodes 62 on both circumferential surfaces, and lead wire 69 was connected to power source 70 and 69' to load resistor 71.

When sound is applied to the transducer, the curvature of the iron surface changes in response to the amplitude of the sound, so that the tension bending the transducer is changed, and the capacitance of the transducer is changed accordingly. In other words, in an equivalent circuit, since the power supply changes in response to the negative vibration of the capacitor of the capacitor to which the bias voltage is applied, a current flows through the load resistor 71. By amplifying the power supply difference caused by the voltage drop of the resistor 71, it was proved that an electrical output was obtained in response to an acoustic signal, and was useful as a high-sensitivity, high-quality microphone.

When the power supply was changed from the DC power supply to the constant voltage power supply of the AC signal of 100 KHz or more, a voice modulated output was obtained. When the audio signal component was detected, a high quality output with less distortion was obtained than the DC power supply.

Example 7

A predistorted transducer 61 using Pb (Mg 1/3 Nb 2/3) O ₃ PbTiO ₃ crab ceramic made in the same manner as in Example 6 was also a donut-type poly having a diameter of 50 mm, an inner diameter of 25 mm, and a thickness of 1.5 mm. It adhere | attached to the carbonate ring 68, and deformed to iron surface. The entire surface of the ceramic is mirror polished, aluminum is deposited thereon, and serves as a mirror and an electrode. Lead wires 72 and 73 were bonded to the electrodes to prepare a voltage variable focusing mirror shown in FIG.

When the parallel beam of light 74 of the laser was irradiated inside the transducer, the laser beam focused at a position 75 about 400 mm in front of the transducer. In this state, 100 volts with direct current voltage applied to the lead wires 72 and 73 was shortened to about 150 mm. Although the change in focal length with respect to the magnitude of the voltage is not linear and is second-order curved, it is this advantage that the relationship between the applied voltage value and the focal length is uniquely determined. The configuration of the value measured while boosting the voltage and the configuration measured while stepping down frequently matched, and no hysteresis phenomenon was observed. With sufficient stability of the human voltage, it has been found that the change in focal length can be made very accurately.

According to the present invention, since the external shape of the ceramic transducer can be arbitrarily selected, the desired vibration mode can be selected, and the shape of the frame of the frame to which the transducer is fixed is also similar to the outward process of the transducer. Since it does not have to be shaped, it does not require high-precision machining and has the effect that mass production is possible at low cost. In addition, according to the present invention, since the deformation of the ceramic transducer is not completely constrained by the frame, but the shape is maintained by the balance of the force with the frame, the transducer may vibrate and cause vibration in the frame. Since the range of vibration is enlarged, the volume is also increased effect. In particular, it is effective to improve the range and volume by fixing on the large plate.

Claims (3)

Transducer having a piezoelectric ceramic plate having a curved surface, electrodes formed on both main surfaces of the piezoelectric ceramic plate, a frame holding the piezoelectric ceramic plate, and a means for applying an electrical signal to the electrodes. The piezoelectric ceramic transducer of claim 1, wherein the holding frame is made of an organic polymer resin. The piezoelectric ceramic transducer according to claim 1, wherein the retaining frame has a flat plate shape and has an opening or a recess in the center portion. The piezoelectric ceramic transducer of claim 1, wherein the piezoelectric ceramic plate is made of a transparent ceramic material.

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