JP2007251358A - Bone conduction speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight bone conduction speaker having a structure hard to be damaged by an external force in which the leakage of a sound is reduced. <P>SOLUTION: A piezoelectric bimorph is covered with an organic material to serve as a bending oscillator 11 to which a rigid body 12 is arranged through a bonding member 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bone conduction speaker suitable for a bone conduction receiver using a piezoelectric vibrator.

  Conventionally, a bone conduction speaker used in a bone conduction receiver mainly includes an electromagnetic bone that uses the same principle as a dynamic speaker and changes a driving force generated by an interaction between a current flowing through a coil and a magnet to mechanical vibration. Conductive speakers are used. A bone conduction receiver using such an electromagnetic bone conduction speaker is disclosed in Patent Document 1 and Patent Document 2.

  Since bone conduction receivers are usually worn on the body and used, light weight is a basic requirement. However, since the electromagnetic bone conduction speaker is composed of a magnet, a yoke, a winding, a vibrating iron piece and the like, there is a problem that the whole bone conduction speaker becomes heavy.

Accordingly, the inventors have proposed a bone conduction speaker having a new configuration in which a piezoelectric bimorph and a flexible organic material are combined in order to solve the above problems. The bone conduction speaker using this piezoelectric bimorph has only some advantages in terms of acoustic characteristics, and only consists of a piezoelectric bimorph composed of a thin piezoelectric ceramic and an elastic shim layer such as a metal and an organic material. By being configured, the bone conduction speaker is extremely light with a total weight of several grams. Such a piezoelectric bone conduction speaker is disclosed in Patent Document 3.

JP 2001-313989 A JP 2002-199480 A JP 2005-175985 A

  However, the piezoelectric bone conduction speaker described above has a problem that the piezoelectric bimorph is easily damaged when subjected to bending stress by an external force because the piezoelectric bimorph that is a component of the piezoelectric bone conduction speaker has a very thin structure. . In order to avoid this problem, a method of protecting the entire bone conduction speaker by placing it in a housing is also conceivable. However, in this method, acoustic vibration generated by a piezoelectric bimorph propagates to the housing and travels from the housing to the surroundings. The phenomenon of “sound leakage” in which sound is emitted occurs and becomes a new problem.

  Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art. Specifically, it is an object of the present invention to provide a piezoelectric bone conduction speaker that is light in weight and has little sound leakage, which is not easily damaged by an external force.

  The present invention employs the following means in order to solve the above problems. That is, the present invention is a structure in which a piezoelectric bimorph is covered with an organic material to form a bending vibrator, and a rigid body is disposed via a bonding member, and the piezoelectric bimorph is housed in a housing, and the gap between the piezoelectric bimorph and the housing is The gist of the invention is to have a structure in which an organic material is filled, or a structure in which the bending vibrator is supported by an elastic material and accommodated in a housing.

  According to the present invention, the bending vibrator for converting an electroacoustic signal into acoustic vibration is a bone conduction speaker formed by joining a rigid body via a joining member, and the bending vibrator has a plate shape having front and back surfaces. The bone conduction speaker is characterized in that the rigid body has a flat surface and is joined via the joining member so that the flat surface of the rigid body and at least one of the front and back surfaces of the bending vibrator face each other. Is obtained.

  The bone conduction speaker according to the present invention uses a piezoelectric ceramic plate made of a piezoelectric ceramic material, and has a device having an electro-mechanical conversion function in which an acoustic vibration is generated according to an electroacoustic signal, or a composite of the device with an organic substance. The device etc. used as a bending vibrator. The bone conduction speaker according to the present invention includes the bending vibrator and a rigid body. The rigid body has a flat surface, and it is preferable that the flat surface and the surface of the bending vibrator are partially bonded by a bonding member so as to face each other or to be parallel to each other. The joining member may be a flexible material such as hard rubber, urethane resin, or silicone resin.

  The rigid body uses a material having rigidity such as metal or resin, and is connected to the bending vibrator partially by a coupling member made of a flexible material, so that the resonance frequency of the bending vibrator is greatly affected. Without giving, the insufficient mechanical strength of the bending vibrator can be reinforced. The rigid body can also function as a support member that supports the bending vibrator to other members, and can be connected and fixed to a holding mechanism of the headset body, for example.

  According to the present invention, the bending vibrator and the rigid body have a rectangular plate shape, and the longitudinal direction of the rigid body is joined in parallel to the longitudinal direction of the bending vibrator. A speaker is obtained.

  According to the present invention, the bending vibrator has a rectangular plate shape, the rigid body has a columnar body, and the longitudinal direction of the rigid body is joined in parallel to the longitudinal direction of the bending vibrator. Thus, a bone conduction speaker can be obtained.

  In order to reduce the size and weight of the bone conduction speaker according to the present invention and satisfy the acoustic performance, it is preferable that the bending vibrator and the rigid body have a rectangular plate shape, and in order to improve the acoustic performance, the rigid body Is preferably arranged so that each longitudinal direction thereof is parallel to the bending vibrator. The same effect can be obtained if the rigid body is not only a rectangular plate but also a columnar body.

  According to the present invention, it is possible to obtain a bone conduction speaker characterized in that the rigid body is formed of a plate-like member and is joined in a state where the plate-like member is bent.

  It is desirable that the rigid body be as light as possible. A rigid body must be able to withstand the bending action caused by external force and be light. However, if the bending resonance frequency of the rigid body itself is in the acoustic frequency region, the rigid body will resist the vibration in the acoustic region generated by the bending vibrator. Resonance and sound leakage occurs. Therefore, it is desirable to adjust the resonance frequency outside the audible acoustic frequency range while maintaining a lightweight rigid body and having a large flexural modulus. Therefore, according to the present invention, the rigid body is made rigid by bending the plate-like member so that the crease is parallel to the longitudinal direction of the plate-like member, and the strength can be secured even with a thin and light material. . In addition, what is necessary is just to set the position and shape to be bent suitably.

  According to the present invention, there is provided the bone conduction speaker, wherein the rigid body has a cross-sectional shape of any one of an H shape, a T shape, a U shape, a convex shape, or an arc shape. can get.

  In the bone conduction speaker according to the present invention, the rigid body arranged parallel to the bending vibrator is a columnar body, and the cross section thereof is H-shaped, T-shaped, U-shaped, convex, or arc-shaped. It is desirable that In addition, as a means for increasing the flexural modulus without increasing the weight of the rigid body, the shape may be molded with resin or the like.

  According to the present invention, the rigid body forms a casing, the bending vibrator is inserted and arranged with a gap with respect to the inner wall of the casing, and the gap is filled with the joining member. A bone conduction speaker is obtained.

  In the bone conduction speaker according to the present invention, the bending vibrator is housed and disposed in a rigid body constituting a housing. In that case, it arrange | positions in a housing | casing so that a clearance gap may be provided with respect to the inner wall of a housing | casing. Further, the gap is filled with a soft elastic material as a joining member. By filling the bonding member in the gap, the bending vibrator and the rigid casing are bonded. In this structure, the housing protects the internal piezoelectric bimorph from external force. At the same time, since the bending vibrator is supported by a soft elastic material, the vibration is not constrained, the acoustic vibration is transmitted to the surface of the housing, and a part of the bone conduction speaker wearer's face is brought into contact with the surface. Audio signals can be heard through bone conduction.

  According to the present invention, it is possible to obtain a bone conduction speaker in which the housing is formed with one or more holes.

  The bone conduction speaker according to the present invention forms a large number of holes in the housing. A housing having a structure with a large number of holes reduces the effective area of vibration, and the effective area of the acoustic radiation surface is reduced, so that a piezoelectric bone conduction speaker that hardly leaks sound can be obtained. Moreover, the hole opened in the housing has an effect of lightening the housing.

  According to the present invention, it is possible to obtain a bone conduction speaker in which at least a part of the surface of the bending vibrator is exposed.

  In the bone conduction speaker according to the present invention, the vibration radiation surface of the bending vibrator is exposed from the housing. Even if the bone conduction speaker housed in the housing is confined in the housing, the surface of the housing functions as a bone conduction speaker because acoustic vibration propagates to the housing via a soft elastic body such as a sponge. However, in order to extract acoustic vibrations most efficiently, the vibration radiation surface of the bending vibrator is exposed on the surface of the housing, and the exposed portion is in contact with a part of the face of the bone conduction speaker wearer. . In this configuration, the acoustic output can be extracted to the maximum while maintaining the function of the casing protecting the bending vibrator.

  According to the present invention, it is possible to obtain a bone conduction speaker in which the casing is formed of a bottomed frame.

  In the bone conduction speaker according to the present invention, the shape of the housing is a bottomed frame, and after housing the piezoelectric bimorph in the frame, a joining member such as urethane rubber or silicone rubber is poured into the frame and cured. Therefore, a bone conduction speaker that is easy to manufacture can be obtained.

  According to the present invention, a bone conduction speaker is obtained in which the bending vibrator is made of a piezoelectric bimorph and an organic material, and the entire surface of the piezoelectric bimorph is covered with the organic material.

  The bone conduction speaker according to the present invention uses a piezoelectric ceramic plate made of a piezoelectric ceramic material, and particularly has two piezoelectric ceramics among devices having an electro-mechanical conversion function that generates mechanical vibrations in accordance with electroacoustic signals. It is preferable to use a piezoelectric bimorph in which the plates are joined so as to sandwich the metal plate. The piezoelectric bimorph is appropriately wired, and the entire surface is covered with urethane rubber, silicone rubber, or the like to form a bending vibrator, thereby obtaining an acoustic vibration generating element having an electro-mechanical conversion function with good acoustic performance for a bone conduction speaker. It is done.

  According to the present invention, it is possible to obtain a bone conduction speaker in which the bending vibrator is a single piezoelectric bimorph.

  The bone conduction speaker according to the present invention has a configuration in which a piezoelectric bimorph is buried in a flexible elastic body in a case having a certain rigidity made of, for example, a metal material. Piezoelectric bimorph is blocked to some extent by the elastic material around it, but by adjusting the hardness of the elastic material and the depth of burial, the vibration output required for the bone conduction speaker can be reduced to the elastic surface. Obtained from. Therefore, the bone conduction speaker according to the present invention has a structure that can sufficiently protect the internal piezoelectric bimorph from external force.

  According to the present invention, there is obtained a bone conduction speaker characterized in that the joining member is made of an elastic material. By using an elastic material such as hard rubber, urethane resin, or silicone resin for the joining member, the displacement of the flexural vibrator is not constrained so much that it does not have a significant effect on the resonance frequency and is sufficient as a bone conduction speaker Acoustic characteristics can be obtained, and stable bonding with the housing can be obtained.

  As described above, according to the present invention, it is possible to provide a piezoelectric bone conduction speaker that is light and has little sound leakage, which is not easily damaged by an external force.

  A bone conduction speaker according to the present invention includes a piezoelectric bimorph covered with an organic material as a bending vibrator, a structure in which a rigid body is disposed via a bonding member, and the piezoelectric bimorph housed in a housing. The gap is filled with a bonding member, or the bending vibrator is supported by the bonding member and housed in a housing.

  Hereinafter, a specific example is given and the bone conduction speaker by this invention is demonstrated in detail, referring drawings.

Example 1
FIG. 1 is a perspective view of a bone conduction speaker according to an embodiment. In the bone conduction speaker 1 according to this example, a rigid body 12 is disposed and fixed on the upper surface of a rectangular plate-shaped bending vibrator 11 via two joining members 13. The bending vibrator 11 is obtained by covering the entire piezoelectric bimorph with an organic material. After silver paste is printed on the front and back surfaces of a rectangular plate having a size of 25 mm × 8 mm × 0.3 mm using piezoelectric ceramics (N10 material) manufactured by NEC TOKIN Corporation, electrodes are provided by baking in the atmosphere, and then at room temperature. Then, a 600V DC voltage was applied between the electrodes for 10 minutes to perform polarization treatment to produce a piezoelectric ceramic plate. Next, a shim plate having a shape dimension of 30 mm × 8 mm × 0.2 mm using 42 alloy material was used. A piezoelectric bimorph was obtained by adhering the piezoelectric ceramic plates to the front and back surfaces using a thermosetting epoxy adhesive so that the polarization directions were the same, and bonding them at a high temperature while applying pressure. Further, after wiring necessary for the piezoelectric bimorph, the entire surface was covered with urethane rubber, which is an organic material, with a thickness of 1 mm or more to form a bending vibrator 11 having an outer dimension of 35 mm × 10 mm × 3 mm.

  The rigid body 12 was a rectangular plate having an outer shape of 35 mm × 10 mm × 1.5 mm, and the weight was reduced by using an aluminum material. The joining member 13 uses hard rubber, which is an elastic material, has an outer dimension of 10 mm × 5 mm × 1 mm, a front surface and a back surface of 10 mm × 5 mm, and the bending vibrator 11 and the rigid body 12 are made of a rubber adhesive. Joined. It is better that the bending vibrator 11 and the rigid body 12 are mechanically strong, but it is necessary that the rigid body 12 does not suppress the vibration of the bending vibrator 11. In this embodiment, both ends of the bending vibrator 11 are connected. The bending vibrator 11 and the rigid body 12 were joined at two points on the inner side.

  When the bone conduction speaker according to the present embodiment is used, the bending vibrator 11 is used while being pressed against a part of the face of the bone conduction speaker wearer. The rigid body 12 is connected to a support device, a headset or the like for determining the position to be pressed. In the bone conduction speaker according to the present embodiment, the rigid body 12 is disposed. Therefore, even if a bending force is applied to the bending vibrator 11 which is a generation source of the acoustic vibration by some external force, the rigid body 12 receives the force. A bending oscillator with low strength is protected from external force.

(Example 2)
FIG. 2 is a perspective view of the bone conduction speaker according to the embodiment. In this embodiment, the rigid body 14 shown in FIG. 2 is used in place of the rigid body 12 used in the first embodiment. The rigid body 14 is made of an aluminum plate having a shape dimension of 35 mm × 14 mm × 0.7 mm, and as shown in FIG. 2, both ends in the short direction are bent 2 mm, and the cross-sectional shape in the short direction is a U shape. It was processed into a pillar body.

  In the bone conduction speaker according to the present embodiment, the bending elastic modulus with respect to the bending of the rigid body 14 greatly increases due to the presence of the bent portion. Therefore, even if the thickness of the aluminum material used is reduced to less than half, It was confirmed that the function of protecting the vibrator was not lost. At the same time, it was confirmed that the resonance frequency did not decrease and there was no problem of sound leakage.

(Example 3)
FIG. 3 is a perspective view of the bone conduction speaker according to the embodiment. In this embodiment, the rigid body 15 shown in FIG. 3 is used in place of the rigid body 12 used in the first embodiment. As the rigid body 15, an aluminum plate having a thickness of 0.3 mm is used, and as shown in FIG. 3, the aluminum plate is bent and passes through the center of the surface and has a convex portion 16 parallel to the longitudinal direction. The shape was made into a column with a convex cross section. In the present embodiment, the convex elastic member 16 can increase the flexural modulus of elasticity of the rigid body 15 by providing the convex portion 16, and it is possible to protect the bending vibrator from an external force in the same manner as in the second embodiment although it is lightweight. In addition, it was confirmed that the bone conduction speaker had a high bending mode resonance frequency and little sound leakage.

  FIG. 4 is a graph showing the frequency characteristics of the generated vibration force of the bone conduction speaker according to the example. In the graph shown in FIG. 4, the horizontal axis indicates the frequency (Hz), and the vertical axis indicates the generated vibration force of the bone conduction speaker according to Examples 1 to 3 in dB with 0 dB = 1N. The generated vibration force indicates the acoustic performance of the bone conduction speaker. Using an artificial mastoid (model 4930) manufactured by Brüel & Kjær, the vibrating body is pressed against the mastoid (mastoid) on the head with a constant load of 3N. The vibrational force received by the auditory nerve part in the head is captured by a force sensor arranged inside and measured in a model manner. As a comparative example A, the measurement result of a bone conduction speaker having only a bending vibrator without a rigid body is also shown in the graph. From the results shown in FIG. 4, it was confirmed that the generated vibration force of the bone conduction speaker according to Examples 1 to 3 was not affected by the rigid body and could be sufficiently put into practical use.

  FIG. 5 is a graph showing frequency characteristics of sound leakage of the bone conduction speaker according to the example. In the graph of FIG. 5, the horizontal axis represents frequency (Hz), and the vertical axis represents the sound leakage pressure of the bone conduction speaker according to Examples 1 to 3 in dB. The leaked sound pressure is obtained by evaluating the sound leak observed at a position 20 cm away from the bending vibrator when the bone conduction speaker is driven at a frequency from 100 Hz to 10 kHz in an anechoic chamber.

  In addition, the graph also shows the measurement results of the bone conduction speaker having only the bending vibrator without the rigid body as the comparative example A and the bone conduction speaker in which the thickness of the rigid body in the example 1 is reduced to 0.5 mm as the comparative example B. . As can be seen from the graph of FIG. 5, in Comparative Example B, in which the thickness of the rigid body is simply reduced, the rigid body resonates, sound leakage increases, and particularly loud noise in the frequency range of 1 to 5 kHz. A leak was observed. Compared to this, it was confirmed that the leakage sound pressure of the bone conduction speaker according to Examples 1 to 3 was sufficiently suppressed.

  As described above, according to the present invention, since the bending vibrator is protected from external force by providing the bending vibrator with a rigid body, a lightweight bone conduction speaker with improved mechanical strength and less sound leakage can be obtained. It was. In the present invention, the means for increasing the bending elastic modulus of the rigid body without increasing the weight is not limited to the material and shape of Example 2 or Example 3, and the material used for the rigid body is resin. Any light and stiff material can be used, and the same effect can be expected if the shape of the cross-sectional second moment increases.

Example 4
FIG. 6 is a cross-sectional view of a bone conduction speaker according to an embodiment. FIG. 6 illustrates the basic configuration of this embodiment. The bone conduction speaker according to the present embodiment has a structure in which the piezoelectric bimorph 21 is housed in the housing 22 and the gap between the piezoelectric bimorph 21 and the inner wall of the housing 22 is filled with an elastic material 23 as a bonding material. The piezoelectric bimorph 21 was the same as the piezoelectric bimorph manufactured in Example 1, and necessary wiring was applied to the piezoelectric bimorph 21 (wiring is not shown). The casing 22 uses a bottomed frame made of an aluminum material having an outer dimension of 33 mm in length, 12 mm in width, 3 mm in height, and 1 mm in thickness, and has a rectangular bottom, and the piezoelectric bimorph 21 is placed in the center of the casing 22. The urethane rubber was poured into the gap between the piezoelectric bimorph 21 and the inner wall of the housing 22 as an elastic material 23, and was cured to form a bone conduction speaker.

  It was confirmed that the bone conduction speaker according to the present example functions sufficiently as a bone conduction speaker when an electroacoustic signal is applied. FIG. 7 is a graph showing frequency characteristics of vibration force generated by the bone conduction speaker according to the example. In the graph of FIG. 7, the horizontal axis indicates the frequency (Hz), and the vertical axis indicates the generated vibration force of the bone conduction speaker according to the present embodiment in dB with 0 dB = 1N. The generated vibration force indicates the acoustic performance of the bone conduction speaker. Using an artificial mastoid (model 4930) manufactured by Brüel & Kjær, the vibrating body is pressed against the mastoid (mastoid) on the head with a constant load of 3N. The vibrational force received by the auditory nerve part in the head is captured by a force sensor arranged inside and measured in a model manner. As a comparative example A, the graph also shows the measurement result of the bone conduction speaker having only the bending vibrator manufactured in Example 1 having no housing.

  As can be seen from the graph of FIG. 7, it was confirmed that the frequency characteristics of the vibration force generated by the bone conduction speaker according to the present embodiment can obtain a sufficient output for practical use although there are some restrictions due to the housing. The bone conduction speaker according to this example was driven by applying a signal of 20 Vrms as an electroacoustic signal, and the surface on which the urethane rubber was exposed was pressed against the periphery of the outer ear, so that the sound could be heard clearly. Also, the sound leakage was almost the same as in Examples 1 to 3.

(Example 5)
FIG. 8 is a perspective view of the bone conduction speaker according to the embodiment. As shown in FIG. 8, the basic configuration of the bone conduction speaker according to the present embodiment is configured such that the bending vibrator 33 is housed in the housing 35. FIG. 9 is a cross-sectional view of a bone conduction speaker according to an embodiment. As shown in FIG. 9, the longitudinal cross-sectional structure of the bone conduction speaker according to the present embodiment shown in FIG. 8 is obtained by covering a piezoelectric bimorph 31 with an organic material 32 and forming a bending vibrator 33 in a casing 35. In addition, the bending vibrator 33 is fixed in the housing 35 with an elastic material 34 interposed as a joining member in the gap between the bending vibrator 33 and the inner wall of the housing 35.

  The bone conduction speaker according to the present embodiment uses the same bending vibrator as that manufactured in the first embodiment as the bending vibrator 33, and has an inner dimension of a length of 37 mm and a width of an aluminum plate having a thickness of 1 mm. A bending vibrator 33 was housed in a casing 35 having a height of 12 mm and a height of 5 mm, and the periphery of the bending vibrator 33 was supported by urethane foam, which is an elastic material 34, to form a bone conduction speaker. It was confirmed that the bone conduction speaker according to the present example can hear sound clearly. In addition, no sound leakage was observed in the high frequency band.

(Example 6)
FIG. 10 is a perspective view of the bone conduction speaker according to the embodiment. The bone conduction speaker according to the present embodiment uses an aluminum plate having 24 holes 0.8 mm in diameter in the range of 1 cm ² and 1 cm ² in place of the case used in the fifth embodiment. Then, the casing 45 having the same size as that of the manufactured Example 5 was used, and the bending vibrator 33 was accommodated in the casing 45. Since the bone conduction speaker according to the present embodiment uses an aluminum plate having a large number of holes 46 for the housing 45, the weight can be further reduced as compared with the fifth embodiment. It was also confirmed that clear sound could be heard as a bone conduction speaker, and no sound leakage was observed in the high frequency band.

(Example 7)
FIG. 11 is a perspective view of the bone conduction speaker according to the embodiment. The bone conduction speaker according to the present embodiment is the same as the bone conduction speaker according to the sixth embodiment except that the upper surface of the housing is removed and the surface of the bending vibrator 33 is exposed on the upper surface of the housing 55 as shown in FIG. It was. Compared with Example 6, the bone conduction speaker according to this example can be further reduced in weight because the housing 55 has no upper surface. It was also confirmed that clear sound could be heard as a bone conduction speaker, and no sound leakage was observed in the high frequency band.

  In order to evaluate the performance of the bone conduction speaker according to Example 5 to Example 7, each generated vibration force was measured. FIG. 12 is a graph showing frequency characteristics of vibration force generated by the bone conduction speaker according to the example. In the graph shown in FIG. 12, the horizontal axis indicates the frequency (Hz), and the vertical axis indicates the generated vibration force of the bone conduction speaker according to Examples 5 to 7 in dB with 0 dB = 1N. The generated vibration force indicates the acoustic performance of the bone conduction speaker. Using an artificial mastoid (model 4930) manufactured by Brüel & Kjær, the vibrating body is pressed against the mastoid (mastoid) on the head with a constant load of 3N. The vibrational force received by the auditory nerve part in the head is captured by a force sensor arranged inside and measured in a model manner. As a comparative example A, the measurement result of the bone conduction speaker having only the bending vibrator 33 without the housing is also shown in the graph.

  As can be seen from the graph shown in FIG. 12, the frequency characteristics of the vibration force generated by the bone conduction speakers according to the fifth to seventh embodiments can provide a sufficient output for practical use although there are some restrictions due to the housing. I was able to confirm. Each of the bone conduction speakers according to Examples 5 to 7 was driven by applying a 20 Vrms signal as an electroacoustic signal, and the wearer pressed against the periphery of the outer ear, so that the sound could be heard clearly.

  FIG. 13 is a graph showing frequency characteristics of sound leakage of the bone conduction speaker according to the example. In the graph of FIG. 13, the horizontal axis represents frequency (Hz), and the vertical axis represents the sound leakage pressure of the bone conduction speaker according to Example 5 and Example 6 in dB. The leaked sound pressure is obtained by evaluating the sound leakage observed at a position 20 cm away from the bending vibrator when the bone conduction speaker is driven at a frequency of 100 Hz to 10 KHz in an anechoic chamber. As can be seen from the graph of FIG. 13, it was confirmed that the bone conduction speaker according to Example 6 uses an aluminum plate having a large number of holes in the housing, thereby greatly reducing sound leakage.

  In Example 6 and Example 7, an aluminum plate having a large number of holes in the housing was used. However, the same effect can be obtained even if the housing is made of a net-like or lattice-like material. Further, if the material used for the housing can secure a certain strength, metals other than aluminum, resin, wood, etc. can be used.

  As described above, according to the present invention, it is possible to provide a piezoelectric bone conduction speaker that is light and has little sound leakage, which is not easily damaged by an external force.

  The bone conduction speaker according to the present invention can be used not only as a receiver for receiving an audio signal, but also for receiving audio from an audio device, a portable terminal device or the like.

The perspective view of the bone conduction speaker by an Example. The perspective view of the bone conduction speaker by an Example. The perspective view of the bone conduction speaker by an Example. The graph which shows the frequency characteristic of the generated vibration force of the bone conduction speaker by an Example. The graph which shows the frequency characteristic of the sound leakage of the bone conduction speaker by an Example. Sectional drawing of the bone conduction speaker by an Example. The graph which shows the frequency characteristic of the generated vibration force of the bone conduction speaker by an Example. The perspective perspective view of the bone conduction speaker by an Example. Sectional drawing of the bone conduction speaker by an Example. The perspective perspective view of the bone conduction speaker by an Example. The perspective perspective view of the bone conduction speaker by an Example. The graph which shows the frequency characteristic of the generated vibration force of the bone conduction speaker by an Example. The graph which shows the frequency characteristic of the sound leakage of the bone conduction speaker by an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bone conduction speaker 11, 33 Bending vibrator | oscillator 12, 14, 15 Rigid body 13 Joining member 16 Convex part 21, 31 Piezoelectric bimorph 22, 35, 45, 55 Case 23, 34 Elastic material 32 Organic material 46, 56 Hole

Claims (12)

  A bending conduction transducer for converting an electroacoustic signal into acoustic vibration is a bone conduction speaker formed by joining a rigid body via a joining member, wherein the bending vibrator has a plate shape having front and back surfaces, and the rigid body A bone conduction speaker having a flat surface, wherein the rigid flat surface and at least one of the front and back surfaces of the bending vibrator are opposed to each other via the bonding member.   2. The bone conduction according to claim 1, wherein the bending vibrator and the rigid body have a rectangular plate shape, and the longitudinal direction of the rigid body is joined in parallel to the longitudinal direction of the bending vibrator. Speaker.   The bending vibrator is formed in a rectangular plate shape, the rigid body is formed in a columnar body, and the longitudinal direction of the rigid body is joined in parallel to the longitudinal direction of the bending vibrator. 2. The bone conduction speaker according to 1.   The bone conduction speaker according to claim 1, wherein the rigid body is made of a plate-like member, and is joined in a state where the plate-like member is bent.   4. The rigid body has an H-shape, a T-shape, a U-shape, a convex shape, or an arc-shaped cross-section. The bone conduction speaker according to any one of 4.   2. The rigid body comprises a housing, the bending vibrator is inserted and disposed with a gap with respect to an inner wall of the housing, and the joining member is filled in the gap. The bone conduction speaker described.   The bone conduction speaker according to claim 6, wherein the housing is formed with one or more holes.   The bone conduction speaker according to claim 6, wherein at least a part of a surface of the bending vibrator is exposed.   The bone conduction speaker according to any one of claims 6 to 8, wherein the casing is made of a bottomed frame.   The bone according to any one of claims 1 to 9, wherein the bending vibrator is made of a piezoelectric bimorph and an organic material, and the entire surface of the piezoelectric bimorph is covered with the organic material. Conductive speaker.   The bone conduction speaker according to any one of claims 6 to 9, wherein the bending vibrator is a single piezoelectric bimorph.   The bone conduction speaker according to any one of claims 1 to 11, wherein the joining member is made of an elastic material.

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