JPH07191679A - Piezoelectric buzzer sounding member - Google Patents

Abstract

PURPOSE:To provide a piezoelectric type buzzer sounding member with which buzzer sounds of a high sound pressure are obtainable by suppressing a higher harmonic component exclusive of a resonance frequency. CONSTITUTION:A supporting body 5 of nearly the same width as the width of a metallic diaphragm 6 stuck with the piezoelectric element 1 and is shorter by a prescribed length than the length of a piezoelectric element 1 is formed on the rear surface of this metallic diaphragm 6 in nearly the central part of the metallic diaphragm 6 in a position corresponding to the piezoelectric element 1. As a result, the piezoelectric type buzzer sounding member has a basic mode of a 1/2 wavelength and vibrates at the resonance frequency of the high sound pressure as the unnecessary higher harmonic components are suppressed. Such piezoelectric type buzzer sounding member produces buzzer sounds with high sounds to the outside even if the sound producing member is disposed within the casing of an electronic apparatus such as electronic clinical thermometer with which liquid tightness is required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a buzzer sounding body having a liquid-tight structure for increasing the sound pressure of a piezoelectric buzzer sounding body fixed in a housing of an electronic device such as a timepiece and an electronic thermometer. It is a thing.

[0002]

2. Description of the Related Art A piezoelectric buzzer sounding body has a buzzer diaphragm having a structure in which a piezoelectric element having a piezoelectric function is attached to a metal diaphragm by a polarization operation. Voltage is applied as a signal and the flexural vibration of the bending of the piezoelectric element is converted into air vibration to generate sound. At this time, the air vibration has a phase of 18
Different from 0 degree, vibrations are canceled out and cannot be taken out as a sound.

Therefore, taking an example of an electronic clinical thermometer, a supporting and fixing portion that acoustically separates and blocks the peripheral portion of the piezoelectric element or the node position inside the peripheral portion is formed, and a hole is opened in the central portion of the surface to make the phase of the surface. Only the sound of is taken and the structure is examined.
However, in such a structure, it is necessary to make a hole for taking out sound in the electronic thermometer housing, and for disinfecting the surface of the housing, it can be wiped with a disinfecting solution such as alcohol or Hibiten solution or immersed in a cleaning solution for cleaning. I could not do it, and there was a problem in practical use.

Further, the presence of the acoustic case thickens the structure of the buzzer sounding body, and the thermometer becomes thicker than necessary, thereby enhancing the discomfort of the subject during the axillary temperature measurement.

Moreover, a buzzer plate is directly attached to the inside of the housing,
A method is used in which the housing is vibrated to take out the sound. However, in that case, the one fixed on the entire surface of the metallic diaphragm backed by the piezoelectric body with an adhesive is
Vibration modes supporting the nodes and the center are complicatedly entangled, and mutual interference suppresses vibration of the buzzer sounding body, and vibrations at harmonics other than the resonance frequency occur, resulting in sufficient energy concentration at the resonance frequency. Without doing so, it was undeniable that the sound pressure of the buzzer sounding body decreased due to the sound pressure other than the audible sound being generated and the sound pressure being attenuated.

[0006]

As shown in the above-mentioned conventional example, the piezoelectric buzzer sounding body such as a measuring instrument and a monitoring / alarming device requiring a liquid-tight structure such as an electronic thermometer has a peripheral support structure and a node. In the structure composed of the support structure, acoustic holes for taking out sound from the surface are provided, so that a closed structure cannot be formed, and the acoustic case has a drawback that it requires a thicker space than necessary.

Further, if the back surface of the buzzer diaphragm is directly fixed inside the housing, the vibration modes of the buzzers interfere with each other in a complicated manner, and the sound pressure is reduced by the sounds of different phases emitted from each other. There is a drawback that energy is dispersed in the wave component and the buzzer sound pressure cannot be obtained efficiently.

The present invention has been made in order to overcome the above drawbacks, and has a piezoelectric buzzer sounding body in which energy is dispersed at a resonance frequency and a buzzer sound pressure can be efficiently obtained, and the same. The purpose is to obtain a liquid-tight electronic device.

[0009]

The present invention for achieving the above object is a piezoelectric buzzer sounding body in which a piezoelectric element is provided on a metallic diaphragm, and the piezoelectric element of the metallic diaphragm is provided. Is provided with a support portion of the piezoelectric buzzer sounding body at a position corresponding to approximately the center of the piezoelectric element on the opposite surface, and the width of the metal diaphragm is substantially the same as the width of the support portion. Formed,
The length of the piezoelectric element is substantially longer than the length of the piezoelectric element, the width of the support is substantially the same as the width of the metal diaphragm, and the length of the support is the length of the piezoelectric element. The piezoelectric buzzer sounding body is characterized in that it is formed to be substantially shorter than the above, and the bonding position of the piezoelectric element is projected by a predetermined length from both ends of the corresponding supporting portion in the length direction. .

According to a preferred aspect of the present invention, the length of each end of the piezoelectric element protruding from both ends of the corresponding support is 20% or more of the length of the support, and the length of the support is the same. Is 20% or more of the length.

In a preferred embodiment of the present invention, the integrated structure is formed by integrally forming a metal vibrating plate and a supporting portion from one metal plate by cutting, rolling, laser processing, corrosion processing such as etching. .

According to a preferred embodiment of the present invention, the metal diaphragm and the supporting portion are integrated with each other, and the metal diaphragm and the supporting portion are formed by processing the same kind or different kinds of metals separately, and then by a bonding method or a welding method. Are joined by.

In a preferred embodiment of the present invention, the support is
It is made of ceramic or metal and is integrated with the metallic diaphragm via an adhesive.

An electronic thermometer is characterized in that an electronic circuit such as the piezoelectric buzzer sounding body and a temperature measuring circuit is provided in a housing in a liquid-tight manner.

As a preferred embodiment of the present invention, the supporting portion of the metallic diaphragm is integrally formed with the metallic diaphragm.

In a preferred embodiment of the present invention, the support portion of the metallic diaphragm is fixed inside the housing with an adhesive.

As a preferred embodiment of the present invention, the buzzer oscillator circuit of the piezoelectric buzzer sounding body is mounted on a printed circuit board, and a spring electrode bent at an angle of about 75 degrees projects from the buzzer sound control electrode, and the printed circuit board is The structure is such that the electrode end is connected to the upper electrode of the piezoelectric element during insertion, and the other electrodes are notched or grooved in a part of the buzzer metal plate and bent to form a lead wire. This structure is connected to the electrodes of the buzzer transmission circuit on the printed circuit board.

The present invention is a piezoelectric buzzer sounding body in which a piezoelectric element is provided on a metal vibrating plate, and the metal vibrating plate is provided on a surface of the metal vibrating plate opposite to the piezoelectric element, substantially in the center of the piezoelectric element. The supporting portion of the piezoelectric buzzer sounding body is provided at a corresponding position, and the width of the metal diaphragm is formed to be substantially the same as the width of the supporting portion. The length is formed to be substantially longer than the length of the piezoelectric element, and the supporting portion is formed by cutting, rolling, laser processing, etching or the like so that its width is substantially the same as the width of the metal diaphragm. The length is formed to be substantially shorter than the length of the piezoelectric element.

The metallic diaphragm and the supporting portion have an integrated structure, and the metallic diaphragm and the supporting portion are made of the same kind or different kinds of metal separately, and then bonded or welded (welded).
Joined by the method.

The bonding position of the piezoelectric element is set so that both ends of the supporting portion in the lengthwise direction protrude. A portion of the protruding structure causes a bending signal in the fundamental mode of 1/2 wavelength to vibrate due to the signal voltage.

Since the supporting portion fixed to the metal diaphragm vibrates the casing efficiently, the piezoelectric buzzer sounding body suppresses unnecessary harmonic vibration and efficiently extracts the buzzer sound to the outside of the casing. be able to.

Further, as is well known, the metal vibrating plate has the surface of the lower electrode of the piezoelectric element or the surface of the metal vibrating plate despite the fact that an electrically insulating adhesive is used in the bonding step with the piezoelectric element. Roughness causes partial contact and electrical continuity.

As a result, since the metal diaphragm is shared with the lower electrode of the piezoelectric element, the width of the diaphragm is substantially the same as that of the piezoelectric element.
Make the length longer than the piezoelectric element Solder or cut out a part on the metal end of the metal diaphragm, and use the bent part as one electrode to guide the electric signal electrode, and the other is directly soldered to the upper electrode of the piezoelectric element. Electrodes are formed by attaching or contacting with elastic (spring-like) electrodes from a printed circuit board on which an electronic circuit is mounted.

The piezoelectric buzzer sounding body according to the present invention does not need a booster circuit even if it is installed in a housing requiring liquid tightness such as an electronic device such as an electronic thermometer. Can be issued.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piezoelectric buzzer sounding body according to an embodiment will be described in detail below with reference to the accompanying drawings.

[Embodiment 1] FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a sectional view. 1 and 2, a piezoelectric buzzer sounding body 100 of the present invention has upper and lower electrodes 2 and 3, and an anaerobic ultraviolet curing adhesive is attached to the lower electrode 3 surface of a ceramic piezoelectric element 1 polarized in the thickness direction. Adhesive (main component: modified acrylate), one-component or two-component type epoxy resin adhesive (main component: epoxy resin polyamidoamine), contact-curable acrylic adhesive (modified acrylic amine compound), etc. 4 A support part 5 is provided on the side opposite to the piezoelectric body (on the back side of the piezoelectric body) at a substantially central portion in the piezoelectric body length direction of the vibrating plate by pressure bonding to the metallic diaphragm 6 via is there. Note that FIG.
2Y + X is the length (mm) of the piezoelectric element 1,
Y represents the protruding length (mm) of the piezoelectric element 1 from the supporting portion 5 in the lengthwise direction, and X represents the length of the supporting portion 5.

As the ceramic piezoelectric element 1, PZT is used.
(PbTiO ₃ —PbZrO ₃ ), or PZT as a main component and Pb substituted with Ba, Sr, Ca, or Pb (Sb _1/2 Nb) in which a third component is added to PZT.
_1/2 ) O ₃ , Pb (Mg _1/3 Nb _2/3 ) O ₃ , Pb (Co _1/3
Complex perovskite type compounds such as Nb _2/3 ) O ₃ and Pb (Ni _1/3 Nb _2/3 ) O ₃ are used.

As the metal diaphragm 6, brass (JISH
3100), phosphor bronze (JISH3110), stainless steel (JISG4307) having spring properties, aluminum (JISH4000), aluminum alloy, iron-nickel alloy, and the like.

The supporting portion 5 has a structure in which the width thereof is substantially the same as that of the vibrating plate 6 and the length thereof has a value of about 1/3 of that of the piezoelectric element.

The thickness t of the supporting portion 5 does not affect the vibration mode of the buzzer and is not particularly specified, but it is 0.05 mm to 1.0 mm, preferably 0.1 m.
It is m-0.3 mm. If the thickness is less than 0.05 mm, the vibration plate may tilt and the other surface may come into contact with the housing when the supporting part is bonded and fixed to the housing, which may interfere with sound transmission. May become thick and may occupy an excessively large area in the housing. Further, it is desirable that the thickness t of the supporting portion 5 be within a dimension obtained by adding the thicknesses of the piezoelectric element 1 and the diaphragm 6 to the thickness of the piezoelectric element. Further, the support portion 5 may be formed integrally with the diaphragm 6.

When the supporting portion 5 is a member separate from the vibrating body 6, a sintered body of powder metal such as brass, phosphor bronze, aluminum alloy or the like can also be used.

The piezoelectric buzzer sounding body is adhered to the housing (not shown) by applying the adhesive 4a to the entire bottom surface of the support portion 5, pressurizing and adhering it to a predetermined position of the housing, and leaving it for a predetermined time. Complete. The adhesive 4a used here is not particularly limited as long as it is an adhesive such as a commercially available epoxy-based adhesive, acrylic-based adhesive, rubber-based adhesive instant adhesive or the like that can bond the housing and the support portion 5 together. However, it is preferable to select a material having good adhesiveness as both the support member material and the housing material.
FIG. 3A is a cross-sectional view in the longitudinal direction when the piezoelectric buzzer sounding body of the embodiment shown in FIGS. 1 and 2 is mounted in a housing.

Thickness 0.4 mm, width 8 mm, length 26 mm
0.2mm thick, 8mm wide and 26mm long from the phosphor bronze plate 6
A diaphragm 6 having a size of mm and a thickness of 0.2 mm, a width of 8 mm, and a length of 7 mm is formed in a substantially central portion of the back surface by a cutting process so as to be symmetrical with the substantially central supporting portion 5 of a diaphragm 6. Width 7mm, length 18mm, thickness 0.2m at almost center position
After the gold electrodes were formed on the upper electrode 2 and the lower electrode 3 of m by vapor deposition (that is, the protruding length was set to 5.5 mm), the piezoelectric element (PZT) 1 that was polarized was used as an anaerobic ultraviolet curing type. Adhesive 4e was applied and pressure-bonded.

Thereafter, the adhesive 4e protruding from the end of the piezoelectric element 1 was cured by an ultraviolet curing device to form a piezoelectric buzzer sounding body. The bottom surface 5b of the support portion 5 of the piezoelectric buzzer sounding body was coated with a room temperature curable epoxy adhesive 4f on almost the entire surface thereof, inserted into the housing 13, and allowed to stand at room temperature for about 24 hours to be cured and adhered and fixed. A perspective view of the entire housing 13 is shown in FIG.

The lead wires 9 and 10 are led out from the printed circuit board 11 which is inserted into the housing 13 having no sound emitting hole, and are attached to the vibrating plate 6 and the upper electrode 2 of the piezoelectric element 1 by a soldering iron. Each of them was coupled and enclosed in a housing 13 together with a buzzer oscillation circuit shown in FIG.

In order to prevent the sound from leaking, a temperature sensitive part such as a thermistor is housed, the diameter is reduced and extended, and a stainless steel cap 13a is fitted with an adhesive to the extended end portion, and the rear end portion is exposed to the temperature and the like. After inserting the printed circuit board 11 on which the display unit, the electronic circuit and the like are mounted into the housing 13, a cap 13b made of the same material as the housing 13 was fused by ultrasonic fusion. The display window portion 13c for displaying the temperature and the like is also formed liquid-tight with the housing 13 by multicolor (two-color) molding or the like. Therefore, this electronic thermometer has a liquid-tight structure.

The housing 13 is made of a plastic material used for an electronic thermometer, which has a thickness A of 1.1 mm.
BS (acrylonitrile butadiene styrene) resin was used.

The measurement and analysis of the buzzer sound was performed by setting the standard microphone at a distance of 10 cm with the electronic thermometer in the anechoic box facing the front with the housing side 13 with the piezoelectric buzzer sounding body fixed. .

The value of the buzzer sound measured by the standard microphone was measured by a precision sound level meter, and the frequency of the sound component was analyzed by an FFT analyzer.

An aluminum block having a built-in heater is prepared in advance for the temperature sensing part of the electronic thermometer, the heat sensing part is heated, and the sound pressure from the piezoelectric buzzer sounding body that notifies the end of the measurement by heating operation is measured and evaluated. At the same time, the frequency components were analyzed.

The buzzer sound pressure of the buzzer sounding body driven by the square wave of 3.0 V, 4 KHz output from the LSI provided on the printed board 11 is 64 dB (decibel), and the waveform component is 85% of 4 KHz component. Harmonic component of 1
It was 5%.

In FIG. 3 (c), the metallic vibrating plate 6 is provided with lead wires 7 and 8 for applying an alternating voltage of the piezoelectric buzzer sounding body.
And a signal cable provided on the upper electrode 2 of the piezoelectric element 1 by spot welding, soldering, or the like.

[Embodiment 2] FIG. 4A shows another embodiment of the present invention. As shown in FIG. 4B, a notch or groove 7a is formed in a part of the metal diaphragm 6. The lead wire 9 is provided and bent. FIG. 4C is a longitudinal sectional view showing a mounted state, in which the printed circuit board 11 is provided with the electrode pads 12a and 12b, and the electrode pad 12a and the lead wire 9 and the electrode pad 12b and the lead wire 10 are electrically connected, respectively. It is connected to the. The other structure of the piezoelectric buzzer sounding body 100 is similar to that shown in FIG.

Thickness 0.4 mm, width 8 mm, length 26 mm
0.2mm high, 8mm wide, 26m long from the phosphor bronze plate
7m from the end to the center in the longitudinal direction
Height 0.2 mm, width 8 mm, length 7 from position moved by m
The upper electrode having a width of 7 mm, a length of 20 mm, and a thickness of 0.2 mm from the surface end symmetrical to the end of the vibration plate on the projection side of the metallic diaphragm 6 manufactured by cutting the mm-shaped support 5 2. After the lower electrode 3 was formed by the same method as in Example 1, a piezoelectric element obtained by applying 4 g of an acrylic adhesive to the piezoelectric element 1 that was polarized was pressure-bonded.

After that, 4 g of the adhesive protruding from the end of the piezoelectric element was wiped off and cured at room temperature, and then used as a piezoelectric buzzer sounding body. The bottom surface 5 of the support portion 5 of the piezoelectric buzzer sounding body
Room temperature curable epoxy adhesive 4c was applied to b almost all over the surface, fixedly adhered to the inside of the same housing 13 as in Example 1 and left at room temperature for 24 hours for curing and adhesion.

For the lead wires 9 and 10, one of them is cut at the other end of the metal vibrating plate 6 with a width of about 1 mm and a length of about 5 mm and bent at an angle of about 75 degrees with respect to the piezoelectric body to produce a buzzer. The electrode 9 is brought into contact with the electrode pad 12a of the printed circuit board 11, and the other electrode 10 is provided with a spring electrode at an angle of about 75 degrees with respect to the other electrode pad 12b provided on the printed circuit board 11. The printed circuit board 11 was brought into contact with the housing 13 in an inserted state, and the printed board 11 was sealed in the same housing 13 as in Example 1 together with the buzzer oscillation circuit shown in FIG. 7B. Finally, the electronic thermometer housing is fitted with a stainless steel cap similar to that of the first embodiment together with an adhesive so that sound does not leak, and the rear end is made of the same material as the housing as in the first embodiment. Were fused by ultrasonic fusion. Therefore, this electronic thermometer has a structure having the same liquid tightness as that of the first embodiment.

The buzzer sound was measured and analyzed in the same manner as in Example 1.

The buzzer sounding body driven by a square wave of 3.0 V and 4 KHz output from the LSI provided on the printed circuit board 11 has a buzzer sound pressure of 64 dB (decibels) and a waveform component of 85% of 4 KHz component. Harmonic component of 1
It was 5%.

[Embodiment 3] FIG. 5 shows another embodiment of the present invention. The metal diaphragm 6 has a thickness of 0.1 mm.
A projecting support 5 having a thickness of 0.2 mm, a width of 8 mm and a length of 7 mm is formed in a substantially central portion of a phosphor bronze plate having a width of 8 mm and a length of 26 mm.
(Thickness: 0.2 mm, width: 8 mm, length: 7 mm) were formed by bonding and curing a phosphor bronze plate made of the same material with an epoxy adhesive 4d.

Next, a piezoelectric element having a width of 7 mm, a length of 18 mm, and a thickness of 0.15 mm is provided at a substantially central position on the opposite side of the supporting part 5 at the substantially central part of the phosphor bronze plate which becomes the metallic vibrating body 6, and at a central position. An anaerobic UV-curable adhesive 4e (1) was formed by printing the silver electrodes on the upper and lower surfaces by screen printing, and then forming the upper electrode 2 and the lower electrode 3 by underbaking treatment and polarization treatment. It was applied and pressure-bonded. Then, the adhesive 4e protruding from the end of the piezoelectric element 1 was cured by an ultraviolet curing device to form the piezoelectric buzzer sounding body 100. The bottom surface 5a of the support portion 5 of the piezoelectric buzzer sounding body 100 is coated with a room temperature curing type epoxy adhesive 4f on almost the entire surface thereof, and as shown in FIG.
It was fixed in the same housing as in (b) and left at room temperature for 24 hours for curing and adhesion, and then fixed.

As for the lead wires, the lead wires 9 and 10 are taken out from the printed board 11 inserted in the housing 13, and are connected to the vibration plate and the piezoelectric element by a soldering iron, respectively, and together with the buzzer oscillation circuit shown in FIG. I sealed it.

The housing 13 used as an electronic thermometer,
The same one as in Example 1 was used. In order to prevent sound leakage, a temperature sensitive part such as a thermistor is housed, a diameter is reduced and extended, a stainless steel cap 13a is fitted together with an adhesive at the front end portion, and a rear end portion is a display portion for displaying temperature and the like, After inserting the printed circuit board 11 on which an electronic circuit or the like is mounted into the housing 13, a cap made of the same material as the housing 13 was fused by ultrasonic welding. Therefore, this electronic thermometer has a liquid-tightness structure equivalent to that of the thirteenth embodiment.

The buzzer sound was measured and analyzed in the same manner as in Example 1.

The buzzer sound pressure of the buzzer sounding body driven by the square wave of 3.0 V, 4 KHz output from the LSI provided on the printed circuit board 11 is 59 dB (decibel) or more, and the waveform component is 4 KHz component 70% or more. , Other harmonic components were less than 30%. [Example 4] Example 3 except that the length of the piezoelectric element was 20 mm, the length of the supporting portion was 4 mm, and the protruding length was 8 mm.
A buzzer sounding body similar to that of Example 1 was formed, the buzzer sounding body was driven by the same circuit as in Example 1, and the buzzer sound was analyzed in the same manner as in Example 1. As a result, L provided on the printed circuit board 11 was detected.
The buzzer sound pressure of the buzzer sounding body driven by the square wave of 3.0 V and 4 KHz output from SI was 59 dB (decibel), the waveform component was 70% of the 4 KHz component, and the other harmonic components were 30%. .

[Embodiment 5] A piezoelectric element having a length of 20 mm,
A buzzer sounding body similar to that of Example 3 was formed except that the length of the supporting portion was 7 mm and the protruding length was 6.5 mm, and the buzzer sounding body was driven in the same circuit as that of Example 1, and Example 1 was used. When the buzzer sound was analyzed in the same manner as above, printed circuit board 1
3.0V, 4KH output from the LSI provided in 1.
The buzzer sound pressure of the buzzer sounding body driven by the square wave of z is 6
The waveform component is 2 dB (decibel), and the 4 KHz component is 80.
%, And other harmonic components were 30%.

Example 6 The length of the piezoelectric element is 20 mm,
A buzzer sounding body similar to that of Example 3 was formed except that the length of the supporting portion was 10 mm and the protruding length was 5 mm, and the buzzer sounding body was driven by the same circuit as that of Example 1, and was similar to that of Example 1. When the buzzer sound was analyzed by
3.0V, 4KHz output from the LSI installed in
Sound pressure of the buzzer sounding body driven by the square wave is 64
In terms of dB (decibel), the waveform component is 85% of the 4 KHz component,
The other harmonic components were 15%.

[Embodiment 7] A piezoelectric element having a length of 20 mm,
A buzzer sounding body was formed in the same manner as in Example 3 except that the length of the supporting portion was 13 mm and the protruding length was 3.5 mm. The buzzer sounding body was driven by the same circuit as in Example 1, and Example 1 was used.
When the buzzer sound was analyzed in the same manner as described above, 3.0V, 4K output from the LSI provided on the printed circuit board 11
The buzzer sound pressure of the buzzer sounding body driven by the square wave of Hz is 64 dB (decibel), and the waveform component is 4 KHz component is 85.
%, And other harmonic components were 15%.

[Embodiment 8] The length of the piezoelectric element is 20 mm,
A buzzer sounding body similar to that of Example 3 was formed except that the length of the supporting portion was 16 mm and the protruding length was 2 mm, and the buzzer sounding body was driven by the same circuit as that of Example 1, and was similar to that of Example 1. When the buzzer sound was analyzed by
3.0V, 4KHz output from the LSI installed in
The sound pressure of a buzzer sounding body driven by a square wave is 59
In terms of dB (decibel), the waveform component is 4% at 70%,
Other harmonic components were 30%.

[Embodiment 9] The length of the piezoelectric element is 21 mm,
Example 1 A buzzer sounding body similar to that of Example 3 was formed except that the length of the support portion was 7 mm and the protruding length was 7 mm.
The buzzer sounding body was driven by a circuit similar to that, and the buzzer sound was analyzed in the same manner as in Example 1. As a result, it was driven by a square wave of 3.0 V, 4 KHz output from the LSI provided on the printed board 11. The buzzer sound pressure of the buzzer sounding body is 66d.
In B (decibel), the waveform component was 88% for the 4 KHz component and 12% for the other harmonic components.

[Embodiment 10] The length of the piezoelectric element is 14 m.
m, the length of the supporting portion was 5 mm, and the protruding length was 6 mm. A buzzer sounding body similar to that of Example 3 was formed, and the buzzer sounding body was driven by the same circuit as that of Example 1, and Example 1 was used. When the buzzer sound was analyzed in the same manner as above, printed circuit board 1
3.0V, 4KH output from the LSI provided in 1.
The buzzer sound pressure of the buzzer sounding body driven by the square wave of z is 6
The waveform component is 4 dB (decibel) and the 4 KHz component is 85.
%, And other harmonic components were 15%.

Even if brass, phosphor bronze, stainless steel having a spring property, aluminum, an aluminum alloy, or an iron-nickel alloy is used as the metal diaphragm, almost the same effect as that of the first embodiment can be obtained.

Even if the shape of the metal diaphragm is substantially circular, substantially elliptical, oval or the like, substantially the same effect as that of the first embodiment can be obtained.

As a piezoelectric element, PZT is the main component, and P
b substituting with Ba, Sr, Ca, or PZT
To the Pb (Sb _1/2 Nb _1/2 ) O ₃ ,
Pb (Mg _1/3 Nb _2/3 ) O ₃ , Pb (Co _1/3 Nb _2/3 )
_{O 3, Pb (Ni 1/3 Nb} 2/3) same effect substantially Example 1 also using the composite perovskite compound of the O ₃ and the like can be obtained.

Even if a protrusion having the same shape and size as those of the first embodiment is provided in the housing as the supporting portion, the same effect as that of the first embodiment can be obtained.

Also, as the supporting portion, a ceramic such as aluminum oxide (alumina) or a sintered body of powder metal such as brass, phosphor bronze or aluminum alloy may be used.
The same effect as can be obtained.

Although an example of an electronic thermometer has been shown as a mounting example, it is not limited to the embodiment, and not only an electronic device such as a wristwatch which requires liquid-tightness, but also an infusion solution which does not require liquid-tightness. Medical devices such as pumps, syringe pumps, extracorporeal blood circulation circuits, biological information measuring devices such as electronic sphygmomanometers and electrocardiographs, electric kettles, electronic jars, microwave ovens, alarm devices for household electric appliances such as water heaters, etc. It can also be applied to industrial notification devices. Also, when mounting on an electronic thermometer, if a solar battery or a secondary battery is provided as a power supply battery inside the housing and a switch for turning on and off the electronic circuit is a magnet reed switch, it is not necessary to replace the battery, and Liquid tightness is further improved.

Comparative Example 1 As shown in FIG.
Vibrating body 1 made of phosphor bronze plate having a width of 4 mm, a width of 8 mm and a length of 26 mm
7mm wide, 21mm long, 0.2m thick in the center of
The anaerobic UV-curable adhesive 4e was applied to the piezoelectric element 1 subjected to the polarization treatment of m and pressure-bonded. After that, the adhesive 4e protruding from the end of the piezoelectric element was cured by an ultraviolet curing device to form a piezoelectric buzzer sounding body. A room temperature curable epoxy adhesive was applied to almost the entire bottom surface of the piezoelectric buzzer sounding body, fixedly adhered inside the housing 13 made of the same material as in Example 1, and left standing at room temperature for 24 hours for curing adhesion. As for the lead wires 9 and 10, the lead wires are taken out from the printed circuit board 11 which is inserted into the housing 13 similar to that of the first embodiment, and are connected to the vibrating plate 6 and the piezoelectric element 1 by a soldering iron, respectively, as shown in FIG. It was enclosed in the housing 13 together with the buzzer oscillation circuit shown.

Finally, in order to prevent sound from leaking from the housing 13, a stainless steel cap similar to that of the first embodiment is fitted to the tip end together with an adhesive, and a cap made of the same material as the housing is ultrasonically fused at the rear end. Fused. Therefore, this electronic thermometer has a structure having the same liquid tightness as that of the first embodiment.

The buzzer sound was measured and analyzed in the same manner as in Example 1.

The buzzer sound pressure driven by the square wave of 3.0 V, 4 KHz output from the LSI provided on the printed board 11 is 48 dB (decibel), and the waveform component is 4 KHz.
The component was 40% and the other harmonic components were 60%.

Comparative Example 2 The piezoelectric buzzer sounding body of Comparative Example 1 was mounted in the same manner as in Example 1, and a buzzer oscillator circuit provided with a booster circuit (boost coil) as shown in FIG. 7A was used. The buzzer sound was measured and analyzed in the same manner as in Example 1. However, the buzzer sound pressure driven by the square wave of 3.0 V, 4 KHz output from the LSI provided on the printed circuit board 11 was 58 dB (decibels). ), The waveform component is 4KHz component is 4
0% and other harmonic components were 60%.

[0072]

As described in detail above, in the piezoelectric buzzer sounding body according to the present invention, unnecessary harmonic components can be suppressed even if the booster circuit is not provided even inside the liquid-tight housing. Energy is concentrated on the resonance frequency, and it is possible to efficiently generate excellent buzzer sound pressure to the outside.

The length of the both ends of the piezoelectric element protruding from the both ends of the corresponding supporting portion is set to 20% or more of the length of the supporting portion, and the length of the supporting portion is 20% of the length of the piezoelectric element. With the above, unnecessary harmonic components can be further suppressed.

The integral structure is made by integrally forming the metal vibrating plate and the supporting portion from one metal plate by cutting, rolling, laser processing, corrosion processing such as etching, thereby facilitating the assembly process. Become.

The metal vibrating plate and the supporting portion are integrated with each other. The metal vibrating plate and the supporting portion are formed by separately processing the same kind or different kinds of metals and then joining them by a bonding method or a welding method. By doing so, a component having a simple structure can be easily assembled.

The support portion is made of ceramic or metal,
By being integrated with the metallic diaphragm via an adhesive, parts having a simple structure can be easily assembled.

By providing an electronic circuit such as a piezoelectric buzzer sounding body and a temperature measuring circuit in a liquid-tight manner in the housing, it is possible to electronically perform sterilization by sweeping with alcohol, antiseptic solution or the like, dipping or the like. An electronic device such as an electronic thermometer capable of protecting a circuit can be obtained.

Since the supporting portion of the metallic diaphragm is fixed inside the housing with the adhesive, the shape of the housing can be made simple.

A buzzer oscillator circuit for the piezoelectric buzzer sounding body,
Mounted on a printed circuit board, and from the buzzer sound control electrode approximately 7
The structure is such that the spring electrode bent at an angle of 5 degrees protrudes and the electrode end is connected to the upper electrode of the piezoelectric element when the printed circuit board is inserted. The other electrode is provided with a cutout or groove in a part of the buzzer metal plate. It is a bent lead wire that is connected to the electrode of the buzzer oscillator circuit of the printed circuit board when the printed circuit board is inserted, so it is easy to insert the printed circuit board into the housing and easily make electronic devices such as electronic thermometers. Is assembled.

[Brief description of drawings]

FIG. 1 is a perspective view of a piezoelectric buzzer sounding body according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the piezoelectric buzzer sounding body of FIG.

3A is a mounting cross-sectional view of the piezoelectric buzzer of FIG. 1, and FIG. 3B is a mounting external view of the piezoelectric buzzer.

FIG. 4 (a) shows a second embodiment of the present invention, and FIG. 4 (b) shows a metal diaphragm provided with a notch or groove.

FIG. 5 is a diagram in which the piezoelectric buzzer sounding body of Example 3 is mounted in a housing.

FIG. 6 is a diagram in which a piezoelectric buzzer sounding body of a comparative example is mounted in a housing.

FIG. 7 (b) is a circuit diagram for driving the piezoelectric buzzer sounding body of the embodiment of the present invention, and FIG. 7 (a) is a conventional piezoelectric buzzer sounding body provided with a booster circuit. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body 2,3 ... Electrode 4,4a, 4b, 4c, 4d, 4e ... Adhesive 5 ... Support body 6 ... Vibrating body 7, 8, 9, 10 ... Lead wire 11 ... Printed circuit board 12a, 12b ... Electrode Pad 13 ... Housing

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[Procedure amendment]

[Submission date] April 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a perspective view of a piezoelectric buzzer sounding body according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the piezoelectric buzzer sounding body of FIG.

[3] FIG. 3 (a), mounting cross-sectional view of a piezoelectric buzzer of FIG. 1, FIG. 3 (b) Ri mounting external view der the piezoelectric buzzer, FIG
3 (c) applies the AC voltage of the piezoelectric buzzer sounding body
To the metal vibration plate and the upper electrode of the piezoelectric element.
Signal cable is provided by spot welding or soldering
FIG.

FIG. 4 (a) shows a second embodiment of the present invention, and FIG. 4 (b) shows a metal diaphragm provided with a notch or groove, and FIG. ) Is the mounting state of FIG.
It is a longitudinal cross-sectional view showing a state.

FIG. 5 is a diagram in which the piezoelectric buzzer sounding body of Example 3 is mounted in a housing.

FIG. 6 is a diagram in which a piezoelectric buzzer sounding body of a comparative example is mounted in a housing.

FIG. 7 (b) is a circuit diagram for driving the piezoelectric buzzer sounding body of the embodiment of the present invention, and FIG. 7 (a) is a conventional piezoelectric buzzer sounding body provided with a booster circuit. FIG.

[Description of Reference Signs] 1 ... Piezoelectric body 2, 3 ... Electrodes 4, 4a, 4b, 4c, 4d, 4e ... Adhesive 5 ... Support 6 ... Vibrating body 7, 8, 9, 10 ... Lead wire 11 ... Printed circuit board 12a, 12b ... Electrode pad 13 ... Housing

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Claims (1)

[Claims] 1. A piezoelectric buzzer sounding body in which a piezoelectric element is provided on a metal vibrating plate, wherein the surface of the metal vibrating plate opposite to the piezoelectric element is provided in a substantially central portion of the piezoelectric element. A supporting portion for the piezoelectric buzzer sounding body is provided at a corresponding position, and the metal diaphragm is formed so that its width is substantially the same as the width of the supporting portion, and its length is substantially longer than the length of the piezoelectric element. The supporting portion is formed so that its width is substantially the same as the width of the metal diaphragm, and its length is substantially shorter than the length of the piezoelectric element. The piezoelectric buzzer sounding body is characterized in that the adhering position of each of the two sticks out by a predetermined length from both ends of the corresponding supporting part in the length direction.