JP3871628B2 - Electroacoustic transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroacoustic transducer intended to vibrate a skull and generate sound waves.
[0002]
[Prior art]
Bone-conducting electroacoustic transducers that convert audio signals or music signals into vibrations and vibrate the skull to listen to the signals as sound are in practical use for the hearing impaired and the elderly . In addition, there are some examples that are practically used for hearing aids.
Conventional electroacoustic transducers of this type used a lot of electrodynamics consisting of a magnet and an electric coil as the drive system. However, the electrodynamic type has a large number of parts and is large and uses a magnet. At present, electroacoustic transducers using piezoelectric elements are widely used due to the disadvantage of increasing weight.
[0003]
FIG. 7 shows the structure of a bone-conduction type electroacoustic transducer using a conventional piezoelectric element. In the figure, 1 is a cylindrical casing with one end closed, 2 is a piezoelectric diaphragm, 3 is a holding body for mounting the piezoelectric diaphragm 2 inside the casing 1, and 4 is a vibration of the piezoelectric diaphragm 2. The vibration transmission member which conveys to a listener's head is shown.
The housing 1 is constituted by a cylindrical tubular body whose one opening surface is closed with a bottom plate 1A, and a piezoelectric diaphragm 2 is mounted therein. The piezoelectric diaphragm 2 is sandwiched between ring-shaped holding bodies 3 whose outer peripheral edges are formed of hard plastic, and the casing is formed by pressure contact force of the lid 1B (the lid 1B is fixed to the casing 1 with an adhesive or the like). It is fixed in 1 and supported so that the central part can vibrate freely.
[0004]
A vibration transmission member 4 is mounted at the center of the piezoelectric diaphragm 2 and this vibration transmission member 4 projects outside the casing 1 through a circular hole 1B-1 formed in a lid 1B that closes the opening surface of the casing 1. Is done. A large portion 4A having a large diameter is formed at the tip of the vibration transmitting member 4, and the tip side of the large portion 4A is an arc surface 4B, and the arc surface 4B is pressed against the head of the listener.
FIG. 8 shows how the piezoelectric diaphragm 2 vibrates. Conventionally, since the outer peripheral edge of the piezoelectric diaphragm 2 is sandwiched and fixed by a holding body 3 made of hard plastic, the piezoelectric diaphragm 2 vibrates in a form in which the peripheral edge is fixed.
[0005]
[Problems to be solved by the invention]
In the conventional bone-conducting electroacoustic transducer using a piezoelectric diaphragm, the edge of the piezoelectric diaphragm 2 is not moved freely because the edge of the piezoelectric diaphragm 2 is fixed. For this reason, the effective vibration area of the piezoelectric diaphragm 2 is reduced, and there is a first problem that it is difficult to output low-frequency vibrations.
A conventional bone-conduction electroacoustic transducer using a voltage diaphragm has a second problem that only one piezoelectric diaphragm is used, and a sufficient output is not generated to generate vibration.
A first object of the present invention is to provide an electroacoustic transducer capable of sufficiently reproducing low-frequency sound in a bone-conducting electroacoustic transducer using a piezoelectric diaphragm.
The second object of the present invention is to provide a high-power electroacoustic transducer.
[0006]
[Means for Solving the Problems]
In the present invention, a piezoelectric diaphragm having an outer edge sandwiched between a casing and a polymer gel material having a Young's modulus of 10 kPa to 10 ³ kPa, and an electric power having a vibration transmitting member at the center of at least one vibration surface of the piezoelectric diaphragm. An acoustic transducer is proposed.
In the present invention, the second piezoelectric diaphragm is further sandwiched between the first piezoelectric diaphragm and a polymer gel material having a Young's modulus of 10 kPa to 10 ³ kPa in the same manner as the first piezoelectric diaphragm. Electroacoustic conversion in which a connecting member is sandwiched between the center of the other vibration surface and the center of one vibration surface of the second piezoelectric diaphragm, and a common vibration transmission member is excited by the plurality of piezoelectric diaphragms Suggest a vessel.
[0007]
Action According to the electroacoustic transducer of the present invention, since the piezoelectric diaphragm is used as an excitation method, it can be constituted by only the piezoelectric diaphragm and its holding parts. This makes it possible to reduce the size and weight. In particular, according to the present invention, since the outer edge of the piezoelectric diaphragm is sandwiched by a polymer gel material having a Young's modulus of 10 kPa to 10 ³ kPa, the piezoelectric diaphragm is also deformed and vibrates at the portion sandwiched by the polymer gel material. be able to.
As a result, the effective vibration area of the diaphragm is increased, the output of low frequency is increased, and the first problem can be solved.
Furthermore, according to the present invention, since a plurality of piezoelectric diaphragms are connected by a connecting member to excite a common vibration transmitting member, high output is possible. Thereby, the second problem can be solved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a proposed example of an electroacoustic transducer . 1A shows a cross section on the YY line shown in FIG. 1B, and FIG. 1B shows a cross section on the XX line shown in FIG. 1A. The housing 1 can be made of, for example, hard plastic, and is formed in a cylindrical shape having an inner diameter of about 15 to 25 mm. One opening surface of the housing 1 is closed with a bottom plate 1A, and the other opening surface is closed with a lid 1B adhered with an adhesive.
The cylindrical portion of the housing 1 and the bottom plate 1A are integrally formed of a hard plastic such as ABS resin. The cylindrical portion and the bottom plate 1A are selected to have a thickness that does not resonate with a sound wave generated by driving the piezoelectric diaphragm 2 housed therein and driving the piezoelectric diaphragm 2 housed therein, for example, a thickness of about 3 to 5 mm. Is done. Similarly, the lid 1B is selected to have a thickness of about 2 to 3 mm so as not to resonate with the strength of the housing and the sound wave generated by driving the piezoelectric diaphragm 2. Further, the lid 1B is bonded to the opening end surface of the cylindrical portion constituting the casing 1 with an adhesive that generates strength as a casing and an adhesive force that does not resonate with sound waves generated by driving the piezoelectric diaphragm 2. The
[0009]
The piezoelectric diaphragm 2 is composed of a ceramic disk having a diameter of about 15 to 25 mm and a thickness of about 2 to 3 mm. In the present invention, a polymer gel material 5 having a Young's modulus of 10 kPa to 10 ³ kPa is applied to both surfaces of the outer edge of the piezoelectric diaphragm 2, and the outer edge of the piezoelectric diaphragm 2 is sandwiched between the polymer gel materials 5. For example, silicon gel can be used as the polymer gel material 5 and applied to the inner side from the outer edge of the piezoelectric diaphragm 2 with a width of about 2 to 5 mm. The thickness is set to about 2 to 4 mm, and the thickness of the polymer gel material 5 is set so that the total thickness of the piezoelectric diaphragm 2 and the polymer gel material 5 is slightly larger than the dimension H in the depth direction of the housing 1. To do.
[0010]
The vibration transmitting member 4 is mounted at a substantially central position on the surface of the piezoelectric diaphragm 2 facing the lid 1B. The vibration transmitting member 4 can be made of a hard plastic such as ABS resin like the casing 1 and has a full length of about 10 to 20 mm and a diameter of about 5 to 9 mm. An adhesive is applied to one end face of the vibration transmitting member 4, and the vibration transmitting member 4 is bonded to the central portion of the piezoelectric diaphragm 2 with this adhesive. The adhesive used here firmly connects the piezoelectric diaphragm 2 and the vibration transmitting member 4 in a cured state, but the piezoelectric diaphragm 2 can be deformed following the deformation with respect to the deformation of the piezoelectric diaphragm 2. For example, a pressure-sensitive rubber-based adhesive that increases the adhesive force by compressive force is used.
[0011]
A circular hole 1B-1 having a diameter of, for example, about 10 to 15 mm larger than the diameter of the vibration transmission member 4 is formed in the center portion of the lid 1B that closes one end of the housing 1, and the vibration transmission member is formed through the circular hole 1B-1. The tip of 4 protrudes outside the housing 1. An enormous portion 4A having a diameter that is about 2 to 3 times larger than the diameter of the vibration transmission member 4 is formed at the tip of the vibration transmission member 4. An arc surface 4B is formed on the tip side of the enormous portion 4A, and the arc surface 4B is brought into contact with the head of the listener.
[0012]
FIG. 2 shows an example of a state in which the electroacoustic transducer according to the present invention is mounted on the listener's head. A headband 6 made of, for example, a resin having elasticity is worn between the listener's temporal regions. The headband 6 elastically presses both sides of the listener elastically at both ends due to the spring property. The electroacoustic transducer 10 according to the present invention is attached to one end side or both ends of the headband 6. On the side shown in FIG. 2, a support rod 7 having a diameter of about 7 to 10 mm and a length of about 10 to 20 mm is integrally provided on the peripheral surface of the housing 1 with the same material as the housing 1. 7 and the end portion of the headband 6 are connected by a connecting lever 8, and the electroacoustic transducer 10 is attached to the headband 6. The electroacoustic transducer 10 is pressed against the listener's temporal region by the elasticity of the headband 6, and the tip of the vibration transmitting member 4 is pressed against the listener's temporal region by this pressure contact force. When the piezoelectric diaphragm 2 is excited in this state, the vibration is transmitted to the listener's skull through the vibration transmitting member 4, and the listener can listen to the vibration as sound.
[0013]
FIG. 3 shows a first embodiment of the present invention. In the embodiment shown in FIG. 3, for example, a shock-absorbing synthetic rubber having high vibration absorption along a lid 1 </ b> B that closes one opening surface of the housing 1. The sealing elastic material 9 having a thickness of about 1 to 3 mm and having a thickness of 1 to 3 mm is adhered with an adhesive, and the sealing elastic material 9 closes the gap G generated between the lid 1B and the vibration transmission member 4. In addition, four grooves 11 are formed on the inner peripheral surface of the housing 1 in the vertical direction, for example, at intervals of 90 ° in the circumferential direction. Forming the chamber RO1 formed between the front side of the piezoelectric diaphragm 2 and the lid 1B, and the chamber RO2 formed between the back side of the piezoelectric diaphragm 2 and the bottom plate 1B through the groove 11 and the polymer gel. The case where it is set as the structure connected by the space | gap formed in the non-adhering surface 12 of the material 5 is shown. The sealing elastic member 9 contacts the peripheral surface of the vibration transmitting member 4, and the contact portion is displaced following the vibration of the vibration transmitting member 4 by the contact frictional resistance, and the vibration transmitting member 4 and the sealing elastic member 9 are displaced. The structure does not generate friction between the two.
[0014]
By closing the gap G formed between the vibration transmitting member 4 and the edge of the circular hole 1B-1 formed in the lid 1B with the sealing elastic member 9, it is possible to prevent sound from leaking to the outside. Further, in this embodiment, the chambers RO1 and RO2 formed on the front side and the back side of the piezoelectric diaphragm 2 are communicated by the gap formed by the groove 11 and the non-adhered surface 12 of the polymer gel material 5, Since the air can flow between the two chambers RO1 and RO2 formed in the housing 1 when the piezoelectric diaphragm 2 vibrates, the pressure of the air in the two chambers is kept constant, and the piezoelectric diaphragm It is possible to prevent the vibration of 2 from being disturbed.
[0015]
That is, in this embodiment, since the gap G existing between the lid 1B and the vibration transmitting member 4 is closed with the sealing elastic material 9, the inside of the case 1 is sealed. For this reason, when one of the two air pressures formed inside the housing 1 decreases when the piezoelectric diaphragm 2 vibrates, the other repeats a change that rises. Therefore, the piezoelectric diaphragm 2 is vibrated by air resistance. This causes a disadvantage that the output is reduced.
Therefore, as in this embodiment, by connecting the two chambers RO1 and RO2 in the case 1 by the gap formed by the groove 11 and the non-adhered surface of the polymer gel material 5, the air resistance is reduced, It can be vibrated with high output.
[0016]
FIG. 4 shows how the piezoelectric diaphragm 2 used in the electroacoustic transducer according to the present invention vibrates. As shown in FIG. 4, according to the present invention, the piezoelectric diaphragm 2 is sandwiched by the polymer gel material 5 having a Young's modulus of 10 kPa to 10 ³ kPa, so that the piezoelectric diaphragm 2 is sandwiched by the polymer gel material 5. The part can also vibrate. As a result, the effective vibration area increases and vibrations with a low frequency can be output more efficiently.
If the polymer gel material 5 is too hard, the vibration of the piezoelectric diaphragm 2 is hindered. If the polymer gel material 5 is too soft, when the vibration transmitting member 4 is pressed against the human body, it is crushed and the piezoelectric diaphragm 2 is pressed against the bottom plate 1A. There is a risk of vibration being impossible. For this reason, it is desirable that the polymer gel material 5 has a Young's modulus of 10 kPa to 10 ³ kPa.
[0017]
FIG. 5 shows another modification proposal example. In this proposed example, two piezoelectric diaphragms 2 are arranged in the case 1, and the two piezoelectric diaphragms 2 are connected to each other by a connecting member 13 to excite a common vibration transmitting member 4. Show. Similarly to the vibration transmission member 4, the connecting member 13 can be made of hard plastic such as ABS resin. The two piezoelectric diaphragms 2 are held by being held between the polymer gel materials 5 at intervals of about 2 to 4 mm, for example, and stored in the housing 1. The connecting member 13 is cut to the same length as the facing distance between the two piezoelectric diaphragms 2, and both end surfaces thereof are bonded to the other surface and one surface of the piezoelectric diaphragm 2 with an adhesive.
By driving the two piezoelectric diaphragms 2 in phase with this structure, the excitation force of the vibration transmitting member 4 is doubled and a strong excitation force can be obtained.
[0018]
6 shows a structure in which the sealing elastic material 9 is attached to the proposed example shown in FIG. 5, and a polymer gel at the position of the groove 11 on the inner peripheral surface of the housing 1 as shown in FIGS. 6A and 6B. A second embodiment of the present invention in which the three chambers RO1 and RO2 and RO3 partitioned by the piezoelectric diaphragm 2 on which the non-adhered surface 12 of the material 5 is formed communicates with each other will be described.
With these structures, sound leakage can be prevented, and reduction in output caused by air resistance in the housing 1 can be eliminated.
In the example shown in FIGS. 5 and 6, an example in which two piezoelectric diaphragms 2 are provided in the housing 1 has been described. However, the piezoelectric diaphragm 2 is further connected to the first piezoelectric diaphragm of the second piezoelectric diaphragm. A third piezoelectric diaphragm can be provided by sandwiching the connecting member between the opposite surfaces.
[0019]
【The invention's effect】
As described above, according to the present invention, the support portion of the piezoelectric diaphragm 2 can also vibrate, so that low-frequency vibrations can be produced, and a broadband bone-conducting earphone can be realized.
Further, in the present invention, by adopting a structure in which a plurality of piezoelectric diaphragms are connected and driven, higher output vibration can be obtained even when driven at the same input level as compared with the case of one piezoelectric diaphragm. Can do.
[Brief description of the drawings]
[1] One A for the proposed example will be described is an enlarged sectional view of the Y-Y line shown in FIG. B, B is an enlarged sectional view of the X-X line shown in FIG A.
FIG. 2 is a perspective view for explaining a situation where an electroacoustic transducer according to the present invention is attached to a listener.
3A is an enlarged sectional view on the YY line shown in FIG. B for explaining the first embodiment of the present invention, and B is an enlarged sectional view on the XX line shown in FIG. .
FIG. 4 is an enlarged cross-sectional view for explaining the operation of the piezoelectric diaphragm used in the present invention.
FIG. 5 is an enlarged cross-sectional view for explaining another modification proposal example.
6A is an enlarged cross-sectional view along line YY shown in FIG. B, showing A according to a second embodiment of the present invention . B is an enlarged sectional view on the line XX shown in FIG.
FIG. 7 is an enlarged cross-sectional view for explaining a conventional technique.
FIG. 8 is an enlarged cross-sectional view for explaining a conventional electroacoustic transducer.

Claims (2)

A piezoelectric diaphragm having an outer edge sandwiched between first and second polymer gel materials in a housing;
Wherein one end face is mounted on the central portion of one plane of vibration of the piezoelectric vibrating plate, the tip from the piezoelectric vibrating hole formed in the central portion of the lid facing the one plane of vibration of plate of the housing to the outside A projecting vibration transmitting member ;
An elastic material for sealing that is attached to the lid portion, contacts the circumferential surface of the vibration transmission member in the hole portion, and closes a gap portion between the lid portion and the vibration transmission member;
A groove is provided in the longitudinal direction on the inner peripheral surface of the casing, and the first and second polymer gel materials are removed in accordance with the position of the groove, and are partitioned by the piezoelectric diaphragm in the casing. An electroacoustic transducer characterized in that the two rooms communicate with each other . A first piezoelectric diaphragm having an outer edge sandwiched between first and second polymer gel materials in a housing;
A second piezoelectric vibrating plate sandwiched between the outer edge to the housing facing the said first piezoelectric vibrating plate with the second polymer gel material and the third polymer gel material,
A connection sandwiched between a center portion of the vibration surface of the first piezoelectric diaphragm facing the second piezoelectric diaphragm and a center portion of the vibration surface of the second piezoelectric diaphragm facing the first piezoelectric diaphragm. A member,
One end face is attached to the center of the vibration surface of the first piezoelectric diaphragm opposite to the second piezoelectric diaphragm, and is formed at the center of the lid portion facing the first piezoelectric diaphragm of the housing. A vibration transmitting member whose tip protrudes from the hole formed outside,
An elastic material for sealing that is attached to the lid portion, contacts the circumferential surface of the vibration transmission member in the hole portion, and closes a gap portion between the lid portion and the vibration transmission member;
A groove is provided in the longitudinal direction on the inner peripheral surface of the housing, and the first, second, and third polymer gel materials are removed in accordance with the position of the groove, and the first and second in the housing are removed. An electroacoustic transducer having a structure in which three chambers partitioned by a piezoelectric diaphragm communicate with each other .

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