JPH11155184A - Piezoelectric receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure sufficient sound pressure at a major frequency band by decreasing part of a piezoelectric diaphragm that is in contact with a piezoelectric diaphragm support and fixed mechanically thereto, so as to decrease a fundamental resonance frequency of a piezoelectric receiver. SOLUTION: This piezoelectric receiver 30 consists of a case 32, a rear plate closing an opening of the case 32, and a piezoelectric diaphragm 31 contained in the case 32. The case 32 is made of resin, its inner circumferential wall 42 consists of an inner wall part 42a at an opening side, a large diameter wall 42b and a tapered piezoelectric diaphragm support 42c the diameter of which is made smaller toward a bottom face 43 continuously to the wall 42b. A piezoelectric diaphragm 31 is formed to be a disk and formed by adhering a piezoelectric element 31a to a metal plate 31b. An outer circumferential bottom 31c of the metal plate 31b is fitted and pressed into contact with the tapered piezoelectric diaphragm support 42c, an adhesive 44 having elasticity such as a silicon is coated between an outer circumferential part of the metal plate 31b and the tapered piezoelectric diaphragm support 42c, and the piezoelectric diaphragm 31 is fixed to the case 32 at a prescribed interval S from the bottom 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric receiver used as a receiver of a small information terminal for voice communication such as a portable telephone.

[0002]

2. Description of the Related Art Receivers used in small information terminals for voice communication can be broadly classified into conductive receivers and piezoelectric receivers.

[0003] A conductive receiver requires a voice coil and a magnet due to the principle of operation like a normal electrodynamic speaker, but a piezoelectric receiver does not require a voice coil or a magnet.
Since it has a very simple structure and is suitable for reduction in size and weight, it is widely used as a receiver of a voice communication terminal such as a mobile phone (Japanese Patent Application Laid-Open No. 8-33098).

FIG. 9 is an exploded perspective view showing an example of a typical structure of a conventional piezoelectric receiver, and FIG. 10 is a partial longitudinal sectional view of a housing containing a piezoelectric vibration plate. According to FIGS. 9 and 10, reference numeral 11 denotes a disk-shaped piezoelectric vibrating plate constituted by bonding a piezoelectric element 11a having electrodes formed on both surfaces of a piezoelectric ceramic to a metal plate 11b, and 12 denotes a piezoelectric vibrating plate 11. A resin housing that holds a predetermined gap at the bottom thereof. The housing 12 has a bottom surface, not shown, for emitting sound waves generated by the vibration of the piezoelectric vibration plate 11 to the outside of the housing 12. A sound emission hole is provided. A back plate 13 is press-fitted into the housing 12 to close the opening of the housing 12. A small hole 14 for resonance damping is formed at a substantially central portion of the back plate 13. A cotton cloth (not shown) is attached as an acoustic resistance material. Instead of attaching a cotton cloth to the small holes 14, a plurality of thin tubes may be provided on the back plate 13. Reference numerals 15 and 15 denote metal terminals respectively connected to the piezoelectric element 11a and the metal plate 11b by soldering in order to apply an external AC voltage to the piezoelectric vibration plate 11.

As shown in FIG. 10 and a partially broken plan view of FIG. 11 showing the piezoelectric vibrating plate 11 housed in the housing 12 in an enlarged scale, a stepped step is formed on the inner peripheral side wall 22 of the housing 12. The piezoelectric vibrating plate holding portion 23 is formed over the entire circumference, and the piezoelectric vibrating plate holding portion 23 has a metal plate 11 of the piezoelectric vibrating plate 11.
The entire outer periphery of “b” is placed and fixed by using an adhesive such as silicon.

As a result, in the conventional piezoelectric receiver, the outer peripheral portion of the metal plate 11b of the circular piezoelectric vibrating plate 11 is held by the piezoelectric vibrating plate holding portion 23 of the housing 12 with a predetermined width and per surface over the entire circumference. It will be fixed.

FIG. 12 shows an acoustic equivalent circuit of the piezoelectric receiver configured as described above. FIG.
According to this, 16 is an input signal source, 11 is a piezoelectric diaphragm, and is represented by an acoustic mass Md and an acoustic stiffness Cd. 17
The back is represented by an acoustic capacitance Cd presented by a small air chamber formed between the piezoelectric vibrating plate 11 and the back plate 13, an acoustic mass Md presented by the small holes 14 for resonance damping, and an acoustic resistance Rc of the cotton cloth. The acoustic circuit on the side of the face plate 13, the acoustic capacitance Cf of the small air chamber formed between the piezoelectric diaphragm 11 and the housing 12 and the housing 12
An acoustic circuit on the housing 12 side represented by an acoustic mass Mf and an acoustic resistance Rf presented by a sound emission hole formed on the bottom surface of the piezoelectric device, 19 is between the piezoelectric receiver and a terminal device housing (not shown) in which the piezoelectric receiver is built. The acoustic circuit Ce on the terminal device housing side represented by the acoustic capacity Ce exhibited by the small air chamber formed by the acoustic masses Me and the acoustic resistance Re presented by the sound emission holes provided in the terminal device housing,
Reference numeral 0 denotes an acoustic circuit of sound leakage represented by an acoustic mass Ma and an acoustic resistance Ra represented by a gap formed between the terminal device housing and a human pinna or head during a call using the terminal device. This is the sound circuit of the human ear.

In the acoustic equivalent circuit thus configured, the characteristics of the piezoelectric receiver are usually evaluated as the pressure generated at the end of the ear canal when an electric unit input signal is applied to the piezoelectric receiver. That is, on the equivalent circuit shown in FIG. 12, the voltage Vp applied to the terminal of the ear acoustic circuit 21 determines the characteristics of the piezoelectric receiver.

FIG. 13 shows an example of frequency characteristics of the piezoelectric receiver when there is no acoustic resistance for resonance damping of the piezoelectric diaphragm 11. However, the frequency characteristics in FIG. 13 are shown as a case where there is no sound leakage between the terminal device housing and the human head. In FIG. 13, reference numeral 24 indicates a peak due to the fundamental resonance of the piezoelectric diaphragm 11, and reference numeral 25 indicates the acoustic circuits 18 and 19 in FIG.
And a peak due to resonance between the housing 12 and the terminal device housing.

FIG. 14 shows a frequency characteristic when the resonance peak of the piezoelectric diaphragm 11 is suppressed by using an acoustic resistance material.
Reference numeral 26 denotes a frequency characteristic when there is no sound leakage between the terminal device housing and the human head, and a substantially flat frequency in a band from 0.3 kHz to 3.4 kHz generally required for a mobile phone or the like. The characteristics are realized. Reference numeral 27 denotes a frequency characteristic when there is sound leakage between the terminal device housing and the head of the person. Compared with the frequency characteristic 26, the sound pressure greatly decreases in a frequency band of about 700 Hz or less. ing.

[0011]

The basic resonance frequency of the piezoelectric vibrating plate 11 is as follows if the quality of the piezoelectric vibrating plate 11 is constant.
The acoustic stiffness Cd of the piezoelectric vibrating plate 11 shown in FIG. 12, that is, the hardness of the material constituting the piezoelectric vibrating plate 11 itself and the fixed state of the piezoelectric vibrating plate 11 to the housing 12 are determined. FIG. 15 shows frequency characteristics when the acoustic stiffness of the piezoelectric diaphragm 11 is changed based on the frequency characteristics shown in FIG. According to FIG. 15, when the stiffness value of the piezoelectric diaphragm 11 is increased, the basic resonance frequency is increased, and the output sound pressure is reduced in a frequency band equal to or lower than IkHZ, that is, a main frequency band for voice communication. I understand. Conversely, when the stiffness value of the piezoelectric braking plate 11 is reduced, the basic resonance frequency is reduced, and the output sound pressure in the main frequency band is increased.

Therefore, in consideration of a decrease in sound pressure due to sound leakage between the terminal device housing and the head of the person, the resonance frequency of the piezoelectric diaphragm 11 is reduced, and the output sound in the main frequency band is reduced. It is desirable to design so that the pressure is high.

The diaphragm in the conductive receiver is formed by using a material on a very thin and soft film.
The resonance frequency of the diaphragm can be easily designed to be 1 kHz or less.
1 uses a harder material compared to the diaphragm of the electrodynamic receiver, and furthermore, as shown in FIG. 10, the outer peripheral portion of the metal plate 11b is formed on the stepped piezoelectric diaphragm holding portion 23 over the entire circumference. At the end, it is held and fixed. For this reason, the stiffness value of the piezoelectric diaphragm 11 becomes larger than that of the conductive receiver.

Accordingly, the fundamental resonance frequency of the piezoelectric receiver is higher than that of the electrodynamic receiver. In particular, when there is sound leakage between the terminal device housing and the head of the person, the sound pressure in the main frequency band is reduced. It will not be secured enough.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piezoelectric receiver having a high output sound pressure in a main frequency band of voice communication by lowering a basic resonance frequency by reducing an acoustic stiffness of a piezoelectric braking plate.

[0016]

SUMMARY OF THE INVENTION In view of the above-mentioned object, the present invention provides a piezoelectric vibrating plate in which only an outer peripheral portion of a metal plate is in contact with a piezoelectric vibrating plate holding portion of a housing, or The piezoelectric vibrating plate is fixed to the housing such that the vibrating plate comes into contact with the piezoelectric vibrating plate holding portion via an adhesive such as silicon.

According to the present invention, it is possible to reduce the number of portions where the piezoelectric vibration plate is fixed and mechanically fixed by contacting the piezoelectric vibration plate holding portion, and the stiffness value of the piezoelectric vibration plate can be reduced as compared with the related art. Can also be reduced. As a result,
By lowering the basic resonance frequency of the piezoelectric receiver, it is possible to sufficiently secure sound pressure in a main frequency band even when sound leakage occurs.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a disk-shaped piezoelectric vibration plate constituted by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibration plate holding the piezoelectric vibration plate. A piezoelectric receiver comprising: a housing having a holding portion and accommodating the piezoelectric vibration plate, wherein the piezoelectric vibration plate holding portion is formed on an inner peripheral side wall of the housing, and a metal plate of the piezoelectric vibration plate is provided. The outer peripheral portion of the piezoelectric vibrating plate is supported by supporting the piezoelectric vibrating plate with a gap between the bottom surface of the housing and the piezoelectric vibrating plate. Only the peripheral portion comes into contact with the piezoelectric vibration plate holding portion, so that the acoustic stiffness value of the piezoelectric vibration plate can be reduced, and the basic resonance frequency of the piezoelectric receiver can be lowered.

According to a second aspect of the present invention, there is provided the piezoelectric receiver according to the first aspect, wherein the piezoelectric vibration holding portion is formed in a tapered shape having a smaller diameter toward the bottom of the housing. Since the outer peripheral portion of the metal plate of the braking plate comes into line contact with the piezoelectric vibration plate holding portion, the acoustic stiffness value of the piezoelectric vibration plate can be reduced, and the basic resonance frequency of the piezoelectric receiver can be lowered.

According to the third aspect of the present invention, the contact portion between the inner peripheral portion of the bottom surface of the metal plate of the piezoelectric vibration plate and the piezoelectric vibration holding portion is fixed by inserting an elastic adhesive such as silicon. The piezoelectric vibrating plate is elastically fixed to the housing, so that the acoustic stiffness value of the piezoelectric vibrating plate can be further reduced, and the basic resonance frequency of the piezoelectric receiver is reduced. Can be lowered.

According to a fourth aspect of the present invention, there is provided a disk-shaped piezoelectric vibration plate formed by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibration plate holding portion for holding the piezoelectric vibration plate. And a housing for housing the piezoelectric vibration plate, wherein the piezoelectric vibration plate holding portion is configured by forming an inner peripheral side wall of the housing in a stepped shape, and the stepped portion has Forming a plurality of protrusions in the circumferential direction, placing the outer peripheral portion of the metal plate of the piezoelectric vibration plate on the protrusions, leaving a gap between the bottom surface of the housing and the piezoelectric vibration plate, It is configured to support the piezoelectric vibration plate, and the presence of the protrusion reduces the contact area of the piezoelectric vibration plate with the housing. The present invention according to claim 5, which can prevent inclination with respect to the object, according to claim 4. The projection in the above-mentioned invention is formed so that the height of the piezoelectric vibration plate from the bottom surface of the housing is equal over the entire area, and the piezoelectric vibration plate is fixed at a certain height from the bottom surface of the housing. Will be held horizontally.

The invention described in claim 6 is the invention according to claim 4 or 5.
In the invention described in the above, an elastic adhesive such as silicon is inserted between the outer peripheral portion of the metal plate and the protrusion, and the piezoelectric vibration plate is fixed to the housing, and the piezoelectric vibration plate is attached to the housing. The elastic stiffness of the piezoelectric vibrating plate can be reduced,
The basic resonance frequency of the piezoelectric receiver can be reduced.

According to a seventh aspect of the present invention, there is provided a disk-shaped piezoelectric vibration plate formed by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibration plate holding portion for holding the piezoelectric vibration plate. Wherein the inner diameter of the piezoelectric vibrating plate holding portion is formed to be equal to or slightly larger than the outer diameter of the piezoelectric vibrating plate. An elastic adhesive such as silicon is inserted between the edge of the plate holder and the piezoelectric vibrating plate, and a gap is provided between the bottom surface of the housing and the piezoelectric vibrating plate. The plate is fixedly attached, and the piezoelectric diaphragm is elastically fixed to the housing, so that the acoustic stiffness value of the piezoelectric diaphragm can be further reduced,
The basic resonance frequency of the piezoelectric receiver can be reduced.

According to an eighth aspect of the present invention, the gap between the bottom surface of the housing and the piezoelectric vibrating plate according to the seventh aspect of the present invention is made equal over the entire area. Is held horizontally at a certain height from the bottom surface of the housing.

According to a ninth aspect of the present invention, there is provided a disk-shaped piezoelectric vibration plate formed by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibration plate holding portion for holding the piezoelectric vibration plate. A housing for accommodating the piezoelectric vibrating plate, wherein the piezoelectric vibrating plate holding portion is formed by forming an inner peripheral side wall of the housing in a stepped shape, and A plurality of protrusions are formed on the outer peripheral portion of the metal plate, and the protrusions are mounted on the stepped portion, and the piezoelectric vibration plate is supported with a gap between the bottom surface of the housing and the support. With this configuration, the contact area between the metal plate of the piezoelectric braking plate and the piezoelectric vibration plate holding part can be reduced, the acoustic stiffness value of the piezoelectric vibration plate can be reduced, and the basic resonance frequency of the piezoelectric receiver can be reduced. it can.

According to a tenth aspect of the present invention, there is provided an adhesive material having elasticity such as silicon between the projection formed on the outer peripheral portion of the metal plate and the stepped portion of the piezoelectric vibration holding portion in the ninth aspect of the present invention. Is inserted, and the piezoelectric diaphragm is fixed to the casing. The piezoelectric diaphragm is elastically fixed to the casing, and the acoustic stiffness value of the piezoelectric diaphragm is further increased. Can be reduced, and the basic resonance frequency of the piezoelectric receiver can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is an exploded perspective view showing an example of the structure of a piezoelectric receiver according to Embodiment 1 of the present invention, and FIG. 2 is a part of a housing accommodating the piezoelectric diaphragm in FIG. It is a longitudinal cross-sectional view. According to FIG. 1 and FIG.
Is a piezoelectric receiver, which includes a housing 32, a back plate 33 which is press-fitted into the housing 32 and closes an opening of the housing 32, and a piezoelectric vibration plate 31 housed in the housing 32. .

The casing 32 is made of a resin, and its inner peripheral side wall 42 is temporarily separated from the opening side inner wall 42a by the large diameter wall 42b.
After that, the piezoelectric vibrating plate holding portion 42 having a tapered shape which is continuous with this and has a smaller diameter toward the bottom surface 43 side.
c.

The piezoelectric vibrating plate 31 has a disk shape, and is formed by forming electrodes on both surfaces of a piezoelectric ceramic.
a is bonded to the metal plate 31b. A bottom portion (lower corner in the figure) 31c of the outer peripheral portion of the metal plate 31b fits and abuts on the piezoelectric vibrating plate support portion 42c, and silicon is provided between the outer peripheral portion of the metal plate 31b and the piezoelectric vibrating plate supporting portion 42c. The piezoelectric vibrating plate 31 is fixedly held on the bottom portion 43 of the housing 32 with a predetermined gap S therebetween by applying an adhesive 44 having elasticity such as.

As in the conventional case, a sound emission hole for emitting sound waves generated by the vibration of the piezoelectric vibrating plate 11 to the outside of the housing 32 is provided in the bottom surface 43 of the housing 32.
3, a small hole 34 for resonance damping is formed at a substantially central portion, and a cotton cloth (not shown) is affixed to the small hole 34 as an acoustic resistance material. Also, instead of attaching a cotton cloth to the small holes 34,
A plurality of thin tubes may be provided on the back plate 13.

Metal ends 35, 35 are connected to the piezoelectric element 31a side and the metal plate 31b side by soldering, respectively, so that an external AC voltage is applied to the piezoelectric vibration plate 31.

As a result of this configuration, the piezoelectric receiver 3
Reference numeral 0 indicates that the mechanical contact area of the piezoelectric vibration plate 31 with the metal plate 31b with respect to the housing 32 can be significantly reduced as compared with the conventional one, and the metal plate 31b is elastically bonded by the adhesive 44. Therefore, the acoustic stiffness value of the piezoelectric diaphragm 31 can be reduced, and the basic resonance frequency of the piezoelectric diaphragm 31 is
As shown in FIG. FIG. 4 shows the frequency characteristics of the piezoelectric receiver 30 according to the present embodiment loaded with an acoustic resistance for resonance damping.
36 is a characteristic when there is no sound leakage between the terminal device housing (not shown) and the human head, and 37 is a characteristic when there is sound leakage between the terminal device housing and the human head. Each one,
In the piezoelectric receiver according to the present embodiment, the basic resonance frequency of piezoelectric vibrating plate 31 can be reduced, so that the output sound pressure in a main frequency band can be higher than that of a conventional piezoelectric receiver. Compared to the case of FIG. 13 showing the frequency characteristic of the conventional piezoelectric receiver, FIG. 4 showing the frequency characteristic of the present embodiment shows that even if the sound pressure decreases on the lower frequency side due to sound leakage, a sufficient output can be obtained. And secure voice communication with excellent sound quality.

(Embodiment 2) FIGS. 5 and 6 show Embodiment 2 of the present invention, which differs from Embodiment 1 in that a piezoelectric vibration formed on the inner peripheral side wall 42 of the housing 32 is different from that of Embodiment 1. A plate holding portion 38 is formed in a step shape, and a plurality of (preferably three or four) holding projections 39 are formed on the piezoelectric vibration plate holding portion 38 so as to protrude. The metal plate 31b of the piezoelectric vibration plate 31 is placed, and the piezoelectric vibration plate 31 is fixed to the housing 32 by interposing an elastic adhesive such as silicon between the metal plate 31b and the holding projection 39. Are different.

The holding projections 39 have a flat upper surface, and are all formed at the same height from the bottom surface 43 of the housing 32. The distance S is made uniform.

With this configuration, the positioning of the piezoelectric vibration plate 31 on the housing 32 in the assembly process of the piezoelectric receiver 30 is facilitated, and the parallelism between the piezoelectric vibration plate 31 and the bottom surface 43 of the housing 32 is improved. Is maintained, and the piezoelectric receiver exhibits characteristics similar to those of the first embodiment.

(Embodiment 3) FIG. 7 shows Embodiment 3 of the present invention, which is different from Embodiment 2 in that a piezoelectric vibrating plate holding portion formed on the inner peripheral side wall 42 of the housing 32 is provided. 38 is the same in that it is formed in a step shape, but the piezoelectric vibrating plate holding portion 38 is not provided with holding projections, and instead, the shape of the piezoelectric vibrating plate holding portion 38 is different. That is, the inner diameter of the piezoelectric vibration plate holding portion 38 is equal to the outer diameter of the metal plate 32b of the piezoelectric vibration plate 31, or is formed slightly larger than the outer diameter of the metal plate 32b.

The position of the piezoelectric vibration plate 31 is determined so as to be parallel to the bottom surface 43 of the housing 32 at an appropriate distance and in parallel. And at the determined position,
An elastic adhesive such as silicon is applied between the edge of the metal plate 31 b of the piezoelectric vibration plate 31 and the piezoelectric vibration plate holding portion 38 to fix the piezoelectric vibration plate 31 to the housing 32.

With this configuration, in the piezoelectric receiver 30, the piezoelectric vibrating plate 31 hardly comes into direct contact with the relatively rigid piezoelectric plate holding portion 38. Thus, the acoustic stiffness value of the piezoelectric diaphragm 31 can be reduced, and the same characteristics as in the first embodiment can be exhibited.

(Embodiment 4) FIG. 8 shows Embodiment 4 of the present invention, and is different from Embodiment 3 in that a piezoelectric vibrating plate holding portion formed on the inner peripheral side wall 42 of the housing 32 is provided. 38 is formed in a step shape, but a plurality of gear-shaped projections 40 are formed on the outer peripheral portion of the metal plate 31b of the piezoelectric vibration plate 31,
Only the protrusion 40 is placed on the piezoelectric vibration plate holding portion 38,
The piezoelectric vibration plate 31 is fixed to the housing 32 with an elastic adhesive such as silicon interposed therebetween.

With this configuration, in the piezoelectric receiver 30, in the piezoelectric receiver 30, only the protrusion 40 comes into contact with the piezoelectric plate holding portion 38, which has relatively high rigidity, via the adhesive. As compared with the conventional piezoelectric receiver, the acoustic stiffness value of the piezoelectric diaphragm 31 can be reduced, and the same characteristics as in the first embodiment can be exhibited.

The inner diameter of the piezoelectric vibrating plate holder 38 according to the fourth embodiment is made equal to the outer diameter of the metal plate 32b of the piezoelectric vibrating plate 31, similarly to the piezoelectric vibrating plate holder 38 in the third embodiment. Alternatively, if the outer diameter of the metal plate 32b is slightly larger than the outer diameter of the metal plate 32b, the positioning of the piezoelectric vibration plate 31 in the assembly process of the piezoelectric receiver 30 becomes easy, and the parallelism between the piezoelectric vibration plate 31 and the bottom surface 43 of the housing 32 is maintained. It becomes possible.

[0043]

According to the piezoelectric receiver of the present invention, the portion where the piezoelectric vibration plate comes into contact with the piezoelectric vibration plate holding portion and is mechanically fixed can be reduced, so that the stiffness value of the piezoelectric vibration plate can be reduced by the conventional piezoelectric receiver. Can be smaller. Therefore, lower the basic resonance frequency of the piezoelectric receiver and ensure sufficient sound pressure in the main frequency band even when sound leakage occurs between the terminal device housing such as a mobile phone and the human head. Can be.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of a structure of a piezoelectric receiver according to a first embodiment of the present invention.

FIG. 2 is a partial longitudinal sectional view of a housing accommodating the piezoelectric diaphragm in FIG. 1;

FIG. 3 is a diagram showing frequency characteristics (without a braking resistor) according to the first embodiment of the present invention;

FIG. 4 is a diagram showing frequency characteristics (in the case where a braking resistor is provided) according to the first embodiment of the present invention;

FIG. 5 is a perspective view of a housing containing a piezoelectric diaphragm of a piezoelectric receiver according to a second embodiment of the present invention.

FIG. 6 is a partial longitudinal sectional view of a housing in FIG. 6;

FIG. 7 is a partial longitudinal sectional view of a housing accommodating a piezoelectric diaphragm of a piezoelectric receiver according to a third embodiment of the present invention.

FIG. 8 is a partial plan view of a housing accommodating a piezoelectric diaphragm of a piezoelectric receiver according to a fourth embodiment of the present invention.

FIG. 9 is an exploded perspective view showing an example of the structure of a conventional piezoelectric receiver.

FIG. 10 is a partial longitudinal sectional view of a housing accommodating the piezoelectric diaphragm in FIG. 9;

11 is a partial plan view of a housing accommodating the piezoelectric diaphragm in FIG. 9;

FIG. 12 is a diagram showing an acoustic equivalent circuit of a piezoelectric receiver.

FIG. 13 is a diagram showing frequency characteristics of a conventional piezoelectric receiver (without a braking resistor).

FIG. 14 is a diagram showing the frequency characteristics of a conventional piezoelectric receiver (with a braking resistor).

FIG. 15 is a diagram showing a relationship between an acoustic stiffness value of a piezoelectric diaphragm and frequency characteristics.

[Explanation of symbols]

 Reference Signs List 30 piezoelectric receiver 31 piezoelectric vibration plate 31a piezoelectric element 31b metal plate 32 housing 33 back plate 38 piezoelectric vibration plate holding portion 39 holding protrusion 40 gear-shaped protrusion 42 inner peripheral side wall 42c piezoelectric vibration plate holding portion 43 bottom surface 44 adhesive

Claims (10)

[Claims] 1. A disk-shaped piezoelectric vibrating plate formed by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibrating plate holding portion for holding the piezoelectric vibrating plate, wherein the piezoelectric vibrating plate is housed. The piezoelectric vibrating plate holding portion is formed on an inner peripheral side wall of the housing, and the outer peripheral portion of a metal plate of the piezoelectric vibrating plate is brought into contact with the piezoelectric vibrating plate holding portion. A piezoelectric receiver, wherein the piezoelectric vibrating plate is supported with a gap between a bottom surface of the body and the piezoelectric vibrating plate. 2. The piezoelectric receiver according to claim 1, wherein the piezoelectric vibration holding section is formed in a tapered shape having a smaller diameter toward a bottom of the housing. 3. The piezoelectric vibrating plate according to claim 1, wherein a contact portion between the outer peripheral portion of the metal plate and the piezoelectric vibration holding portion is fixed by inserting an elastic adhesive such as silicon. The piezoelectric receiver as described. 4. A disk-shaped piezoelectric vibrating plate constituted by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibrating plate holding portion for holding the piezoelectric vibrating plate to accommodate the piezoelectric vibrating plate. A piezoelectric receiver, comprising: a piezoelectric vibrating plate holding portion, wherein an inner peripheral side wall of the housing is formed in a stepped shape, and a plurality of protrusions are formed on the stepped portion in a circumferential direction. Form a part,
The outer peripheral portion of the metal plate of the piezoelectric vibration plate is placed on the projection, and a gap is provided between the bottom surface of the housing and the piezoelectric vibration plate to support the piezoelectric vibration plate. And a piezoelectric receiver. 5. The piezoelectric receiver according to claim 4, wherein the protrusion is formed so that the height of the piezoelectric vibration plate from the bottom surface of the housing is equal over the entire area. 6. The piezoelectric vibrating plate according to claim 4, wherein an elastic adhesive such as silicon is inserted between the outer peripheral portion of the metal plate and the projection to fix the piezoelectric vibrating plate to the housing. Piezo receiver. 7. A disk-shaped piezoelectric vibrating plate formed by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibrating plate holding portion for holding the piezoelectric vibrating plate to house the piezoelectric vibrating plate. Wherein the inner diameter of the piezoelectric vibrating plate holding portion is formed equal to or slightly larger than the outer diameter of the piezoelectric vibrating plate, and the edge of the piezoelectric vibrating plate holding portion is An elastic adhesive such as silicon is inserted between the diaphragm and the diaphragm, and a gap is provided between the bottom surface of the housing and the piezoelectric diaphragm to fix the piezoelectric diaphragm to the housing. A piezoelectric receiver. 8. The piezoelectric receiver according to claim 7, wherein the gap between the bottom surface of the housing and the piezoelectric diaphragm is made equal over the entire area. 9. A disk-shaped piezoelectric vibrating plate constituted by bonding a piezoelectric element to a metal plate, and a ring-shaped piezoelectric vibrating plate holding portion for holding the piezoelectric vibrating plate, and accommodating the piezoelectric vibrating plate. A piezoelectric receiver comprising: Forming a plurality of protrusions, placing the protrusions on the stepped portion, placing the piezoelectric vibration plate with a gap between the bottom surface of the housing,
A piezoelectric receiver characterized by being configured to support it. 10. An elastic adhesive such as silicon is inserted between a projection formed on an outer peripheral portion of a metal plate and a step portion of a piezoelectric vibration holding portion, and the piezoelectric vibration plate is fixed to the housing. The piezoelectric receiver according to claim 9, wherein: