JP5576776B2 - Piezoelectric speaker and alarm device using the piezoelectric speaker - Google Patents

Description

  The present invention relates to a piezoelectric speaker that generates sound using a piezoelectric vibrator and an alarm device using the piezoelectric speaker.

  As a conventional piezoelectric speaker, there is known a structure in which an outer peripheral portion of a piezoelectric vibrator in which a piezoelectric element is fixed to a diaphragm is fixed to a storage case with an adhesive (for example, see Patent Document 1). In the conventional piezoelectric speaker, the storage case is composed of two members, and the outer peripheral portion of the piezoelectric vibrator is fixed to the portion where the two members are fitted with an adhesive. As a result, in the conventional piezoelectric speaker, the central portion of the piezoelectric vibrator vibrates and generates sound while the outer peripheral portion of the piezoelectric vibrator is fixed to the storage case.

Japanese Patent No. 3202169

  However, in the conventional piezoelectric speaker, an adhesive is used to fix the outer peripheral portion of the piezoelectric vibrator to the storage case (support member). Therefore, when the two members are fitted together in the manufacturing process of the piezoelectric speaker, the adhesive is used. It was necessary to add the process of apply | coating and the process of drying an adhesive agent. In the step of applying the adhesive, the position where the adhesive is applied and the amount of adhesive applied must be controlled so that the adhesive is not attached to other parts. Moreover, when an adhesive was used, it took time to dry the adhesive. As described above, the conventional piezoelectric speaker has a problem that the manufacturing process becomes complicated by using the adhesive for fixing the piezoelectric vibrator and the storage case.

  Moreover, in the conventional piezoelectric speaker, since the adhesive on the piezoelectric vibrator is cured, a cured portion is generated on the outer peripheral portion of the piezoelectric vibrator. As a result, in the conventional piezoelectric speaker, the vibration of the outer periphery of the piezoelectric vibrator is constrained by the hardened portion, so that the amplitude of the vibration of the piezoelectric vibrator cannot be increased, and sufficient sound pressure is obtained in a wide frequency band. There was a problem that could not be obtained.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a piezoelectric speaker capable of obtaining a sufficient sound pressure in a wide frequency band by a simple manufacturing process, and an alarm device using the piezoelectric speaker. There is.

A piezoelectric speaker according to the present invention includes a piezoelectric vibrator having a piezoelectric body made of a piezoelectric element and a diaphragm that vibrates by deformation of the piezoelectric body, and a thin thickness provided at least around the piezoelectric vibrator in combination with the diaphragm. And a first support body and a second support body that are fixed in position in a state of being fitted to each other, and the first support body and the second support body are fixed in position when the first support body and the second support body are fixed in position. A support member for supporting the thin member by sandwiching an outer peripheral portion of the thin member at a portion where the first support member and the second support member are fitted, and the first support member and the thin member between And the thin member protrudes in a direction opposite to the sound output direction, and the first support body protrudes in a direction opposite to the sound output direction. And sandwiched between the second supports The first support body and the second support body have a sandwiching surface for sandwiching the outer peripheral portion of the thin member, and the sandwiching surface of the first support body and the second support body The sandwiching surface is inclined and formed in a tapered shape, and the inclination angle of the thin member with respect to a plane perpendicular to the direction in which the first support and the second support are opposed to each other is 2 ° to 10 °. der is, the piezoelectric vibrator and the thin thickness member, the shape as viewed from the thickness direction is circular, the ratio of the outer diameter of the thin thickness member to the diameter of the piezoelectric vibrator, 1.45 1.62 It is characterized by the following.

A piezoelectric speaker according to the present invention includes a piezoelectric vibrator having a piezoelectric body made of a piezoelectric element and a diaphragm that vibrates by deformation of the piezoelectric body, and a thin thickness provided at least around the piezoelectric vibrator in combination with the diaphragm. And a first support body and a second support body that are fixed in position in a state of being fitted to each other, and the first support body and the second support body are fixed in position when the first support body and the second support body are fixed in position. A support member for supporting the thin member by sandwiching an outer peripheral portion of the thin member at a portion where the first support member and the second support member are fitted, and the first support member and the thin member between And the thin member protrudes in a direction opposite to the sound output direction, and the first support body protrudes in a direction opposite to the sound output direction. And sandwiched between the second supports The thin member has a protrusion at a portion sandwiched between the first support body and the second support body, and a front end surface of the protrusion is in contact with an inner surface of the thin member. inclined, the inclination angle of the thin thickness member to the first support and the second support and the plane perpendicular to the direction in which the opposing Ri 2 ° to 10 ° der, the piezoelectric vibrator and the thin thickness The member is circular when viewed from the thickness direction, and the ratio of the outer diameter of the thin member to the diameter of the piezoelectric vibrator is 1.45 or more and 1.62 or less .

A piezoelectric speaker according to the present invention includes a piezoelectric vibrator having a piezoelectric body made of a piezoelectric element and a diaphragm that vibrates by deformation of the piezoelectric body, and a thin thickness provided at least around the piezoelectric vibrator in combination with the diaphragm. And a first support body and a second support body that are fixed in position in a state of being fitted to each other, and the first support body and the second support body are fixed in position when the first support body and the second support body are fixed in position. A support member for supporting the thin member by sandwiching an outer peripheral portion of the thin member at a portion where the first support member and the second support member are fitted, and the first support member and the thin member between And the thin member protrudes in a direction opposite to the sound output direction, and the first support body protrudes in a direction opposite to the sound output direction. And sandwiched between the second supports The first support body and the second support body have a sandwiching surface for sandwiching the outer peripheral portion of the thin member, and the sandwiching surface of the first support body and the second support body The clamping surface is formed with a convex portion at a position that does not overlap each other in the direction connecting the center and the outer peripheral portion of the thin member, and is orthogonal to the direction in which the first support body and the second support body face each other. the inclination angle of the thin thickness member with respect to the plane of, 2 ° to 10 ° der is, the piezoelectric vibrator and the thin thickness member, the shape as viewed from the thickness direction is circular, the relative diameter of the piezoelectric vibrator The ratio of the outer diameter of the thin member is 1.45 or more and 1.62 or less .

In this piezoelectric speaker, the inclination angle is preferably 2 ° to 4 ° .

  In the piezoelectric speaker, the thin member protrudes in a direction opposite to a surface of the diaphragm on which the piezoelectric body is provided, and is sandwiched between the first support body and the second support body. preferable.

  In this piezoelectric speaker, the elastic body is preferably a thermoplastic elastomer.

  In the piezoelectric speaker, the first support is preferably a thermoplastic material, and is formed by simultaneous molding with the elastic body.

  In this piezoelectric speaker, the elastic body is preferably a polyurethane foam.

  In this piezoelectric speaker, the thin member is preferably a plastic film.

  In this piezoelectric speaker, it is preferable that the resonance frequency of the thin member is determined within a predetermined range including a frequency that is 1: 1 with the resonance frequency of the piezoelectric vibrator.

  In this piezoelectric speaker, it is preferable that the thin member has a corrugation formed of at least one of a peak portion and a valley portion formed in an annular shape.

  The alarm device according to the present invention includes the piezoelectric speaker, a sensor that detects a surrounding abnormality, and a signal output unit that outputs an electrical signal that informs the surrounding abnormality to the piezoelectric speaker when the surrounding abnormality is detected by the sensor. And a housing in which the piezoelectric speaker, the sensor, and the signal output unit are housed and the support member is integrally provided.

  According to the present invention, the first support body and the second support body of the support member sandwich the outer peripheral portion of the thin member to support the thin member, so that the step of applying the adhesive and the adhesive are dried. No process is required. As a result, in the present invention, the manufacturing process can be simplified.

  In the present invention, since the first support and the second support support the thin member by sandwiching the outer peripheral portion of the thin member, the thin member is fixed to the support member using an adhesive. In contrast, it is possible to eliminate the hardened portion by the adhesive in the thin member. At the same time, in the present invention, since the elastic body is provided between the first support and the thin member, the outer peripheral portion of the thin member is fixed more than necessary by the first support and the second support. Can be prevented. As a result, the present invention can reduce the factor that restrains the vibration of the thin member as compared with the case where the thin member is fixed to the support member using an adhesive, and therefore the amplitude of the thin member during vibration can be reduced. The acoustic impedance, that is, the sound pressure in a wide frequency band can be increased.

1 is a piezoelectric speaker according to Embodiment 1, wherein (a) is a cross-sectional view of a state in which a front side support and a rear side support are fitted together, and (b) is a front side support and a rear side support. It is sectional drawing before fitting. It is a block diagram of the piezoelectric vibrator which concerns on the same as the above. The piezoelectric vibrator and the thin member according to the above, (a) is an exploded perspective view before fixing, and (b) is a perspective view after fixing. It is a figure which shows the sound pressure level characteristic of the piezoelectric speaker which concerns on the same as the above. It is a figure which shows the acoustic impedance characteristic of the piezoelectric speaker which concerns on the same as the above. It is a disassembled perspective view before fixation of the piezoelectric vibrator and thin member which concern on the modification same as the above. A piezoelectric speaker according to a modification of the above, wherein (a) is a cross-sectional view of a state in which a front side support and a rear side support are fitted together, and (b) is a front side support and a rear side support. It is sectional drawing before and. It is a disassembled perspective view of the smoke detector which concerns on Embodiment 2. FIG. It is a figure which shows the characteristic of the peak sound pressure of the piezoelectric speaker which concerns on Embodiment 3. FIG. It is a figure explaining the diameter ratio of a piezoelectric vibrator and a thin member in the piezoelectric speaker which concerns on the same as the above. It is a figure which shows the principal part of the piezoelectric speaker which concerns on Embodiment 4. FIG. 7 is a main part of a piezoelectric speaker according to a fifth embodiment, where (a) is a cross-sectional view before the front-side support and the rear-side support are fitted together, and (b) is the front-side support and the rear-side support. It is sectional drawing of the state which the body fitted. It is a figure which shows the sound pressure level characteristic of the piezoelectric speaker which concerns on the same as the above. FIG. 10 is a main part of a piezoelectric speaker according to a sixth embodiment, where (a) is a cross-sectional view before the front side support and the rear side support are fitted together, and (b) is the front side support and the rear side support. It is sectional drawing of the state which the body fitted.

(Embodiment 1)
The piezoelectric speaker according to Embodiment 1 is a speaker that generates sound using a piezoelectric vibrator. As shown in FIG. 1, the piezoelectric speaker 1 of the present embodiment includes a piezoelectric vibrator 2, a thin member 3, an elastic body 4, and a support member 5. The piezoelectric speaker 1 outputs an alarm sound and a sound. The alarm sound is a sound in a frequency band near 3 kHz. The sound is a sound wave in a lower frequency band (500 Hz to 1200 Hz) than the alarm sound. Therefore, the piezoelectric speaker 1 is required to increase the sound pressure in a wide frequency band.

  The piezoelectric vibrator 2 has a unimorph structure in which a piezoelectric body 21 and a diaphragm 22 are stacked. As shown in FIG. 2, the piezoelectric body 21 and the diaphragm 22 are both disk-shaped.

The piezoelectric body 21 is composed of a piezoelectric element (piezo element) having an effect of converting an electrical signal into sound (piezoelectric effect). As the piezoelectric element of the present embodiment, lead zirconate titanate (PZT) having a thickness of 0.05 mm or more and 0.15 mm or less is used. Lead zirconate titanate is a mixed crystal of lead titanate and lead zirconate, which are ternary metal oxides. The density of lead zirconate titanate used in the present embodiment is 8.0 × 10 ³ kg / cm ³ .

The diaphragm 22 is brass having a diameter larger than that of the piezoelectric body 21 and a larger area, and a thickness of 0.1 mm or more and 0.25 mm or less. The density of the brass used in this embodiment is in the range of 8.4 × 10 ³ kg / cm ³ or more and 8.5 × 10 ³ kg / cm ³ or less. The thickness of the piezoelectric body 21 and the thickness of the diaphragm 22 are preferably equal. The diaphragm 22 is bonded to the surface of the piezoelectric body 21 concentrically with the piezoelectric body 21 by, for example, an epoxy adhesive.

  Electrodes are provided on the surface of the piezoelectric body 21 with silver having a thickness of about 2 μm. As shown in FIG. 3B, a lead wire 23 is connected to the electrode of the piezoelectric body 21, and a lead wire 24 is connected to the diaphragm 22. Connected to the lead wires 23 and 24 is a connector 25 for electrically connecting to a circuit portion (not shown) for outputting an electrical signal to the piezoelectric speaker 1. For example, lead-free solder is used for the connection between the electrode of the piezoelectric body 21 and the lead wire 23 and the connection between the diaphragm 22 and the lead wire 24, respectively. When a signal voltage is applied to the piezoelectric body 21, the piezoelectric body 21 is distorted and the diaphragm 22 vibrates. That is, the diaphragm 22 vibrates due to the deformation of the piezoelectric body 21.

  As shown in FIG. 3A, the thin member 3 is a resin film (plastic film) formed in a donut shape (annular shape). As the resin film, thermoplastic resins such as PEI (polyetherimide), PC (polycarbonate), and PEN (polyether naphthalate) are used. The thickness of the thin member 3 is preferably in the range of 75 μm or more and 188 μm or less. The thin member 3 is bonded to the piezoelectric vibrator 2 (vibrating plate 22) with, for example, a silicone adhesive or an epoxy adhesive. As a result, the thin member 3 is provided around the piezoelectric vibrator 2 in combination with the diaphragm 22 as shown in FIG. The thin member 3 vibrates together with the diaphragm 22 due to the deformation of the piezoelectric body 21. That is, the thin member 3 has a function as an auxiliary diaphragm.

  The elastic body 4 shown in FIG. 1 is a member formed in an annular shape by a thermoplastic elastomer. The elastic body 4 is provided between a front side support body 51 and a thin member 3 which will be described later.

  The support member 5 includes a front surface side support body 51 and a rear surface side support body 52, and is provided around the thin member 3.

  The front side support body 51 is a member formed in a cylindrical shape from a thermoplastic material. In the present embodiment, a flame retardant ABS resin is used for the front support 51. On the rear surface 511 of the front support 51, a cylindrical protrusion 512 that protrudes in the rear direction (downward in FIG. 1) is provided on the inner peripheral side. The front side support body 51 is formed by simultaneous molding (two-color molding, double molding) with the elastic body 4. Thereby, the elastic body 4 is provided at the front end (lower end in FIG. 1) of the protruding portion 512 of the front side support body 51. The front side support body 51 of this embodiment is corresponded to the 1st support body of this invention.

  The rear side support body 52 is a member formed in a cylindrical shape by a thermoplastic material. In the present embodiment, a flame retardant ABS resin is used for the rear side support body 52. In the front surface 521 of the rear support 52, a recess 522 is formed on the inner peripheral side. The back surface side support body 52 of this embodiment is equivalent to the 2nd support body of this invention.

  The outer peripheral portion of the thin member 3 is placed on the placement surface 523 which is the bottom surface of the recess 522 of the rear support 52 with respect to the front support 51 and the rear support 52 having the above structure. (See FIG. 1 (b)). Thereafter, the front support 51 and the rear support 52 are such that the rear surface 511 of the front support 51 and the front surface 521 of the rear support 52 face each other, and the protrusion 512 of the front support 51 supports the rear support. By entering the recess 522 of the body 52, they are fitted to each other (see FIG. 1A). Thereafter, the front side support body 51 and the rear side support body 52 are fixed in position in a state of being fitted to each other. The front-side support 51 and the rear-side support 52 sandwich the outer peripheral portion of the thin member 3 at a position where the front-side support 51 and the rear-side support 52 are fitted when they are fixed in a fitted state. The thin member 3 is supported. Thereby, since the thin member 3 is reliably attached to the support member 5, the sound pressure and resonance frequency of the sound output from the piezoelectric speaker 1 can be stabilized. The front side support body 51 and the rear side support body 52 can be removed even after the positions are fixed. That is, the front side support 51 and the rear side support 52 are detachable. The user can easily remove the thin member 3 (including the piezoelectric vibrator 2) from the support member 5 by removing the front support 51 from the rear support 52.

  Next, the operation of the piezoelectric speaker 1 of the present embodiment will be described. When a signal voltage is applied to the piezoelectric body 21 by an electric signal from a circuit unit (not shown), the piezoelectric body 21 repeatedly contracts and expands, but the diaphragm 22 neither contracts nor expands. Will bend. When the piezoelectric vibrator 2 repeats the recursion operation, the thin member 3 vibrates together with the piezoelectric vibrator 2. Due to this vibration, the piezoelectric speaker 1 generates sound.

  FIG. 4 shows the sound pressure level characteristics of the sound output from the piezoelectric speaker 1 of the present embodiment. The piezoelectric speaker 1 of the present embodiment has a configuration in which a doughnut-shaped thin member 3 is bonded to a piezoelectric vibrator 2 having a diameter of 35 mm to have a diameter of 50 mm. The sound pressure level characteristic of FIG. 4 is a result when a voltage of 40 Vp-p is applied to the piezoelectric speaker 1 and the sound pressure level at the front position of the piezoelectric speaker 1 is measured. The piezoelectric speaker 1 can increase the sound pressure level in the high frequency band (around 3 kHz), which is the band of the alarm sound, to 100 dB / m or more, and also has the peak sound pressure in the low frequency band (500 Hz to 1200 Hz), which is the voice band. And a sufficient sound pressure level can be obtained.

  FIG. 5 shows acoustic impedance characteristics of the piezoelectric speaker 1 of the present embodiment (solid line in FIG. 5). FIG. 5 also shows an acoustic impedance characteristic of a piezoelectric speaker not provided with a thin member as a comparative example (broken line in FIG. 5). In the piezoelectric speaker of the comparative example, the member that vibrates due to the deformation of the piezoelectric body is a single diaphragm. Since the piezoelectric body 21 exhibits the same characteristics as the capacitor, the acoustic impedance decreases as the frequency increases. The piezoelectric speaker 1 of the present embodiment and the piezoelectric speaker of the comparative example sweep the frequency of sound waves in the range of 400 Hz to 4 kHz when outputting both alarm sound and sound. As described above, the frequency at which the maximum current flows when the frequency of the sound wave is swept is a resonance point near 3 kHz. The acoustic impedance at the resonance point is 600Ω in the present embodiment, and 200Ω in the comparative example. Therefore, the piezoelectric speaker 1 of the present embodiment can be driven with a current amount that is one-third that of the piezoelectric speaker of the comparative example.

  From the above description, according to the piezoelectric speaker 1 of the present embodiment, when the front support 51 and the rear support 52 of the support member 5 are fixed in position, the outer periphery of the thin member 3 is sandwiched and thinned. Since the member 3 is supported, the step of applying an adhesive and the step of drying the adhesive are unnecessary. As a result, in the piezoelectric speaker 1 of this embodiment, the manufacturing process can be simplified.

  Further, in the piezoelectric speaker 1 of the present embodiment, the front side support body 51 and the rear side support body 52 sandwich the outer peripheral portion of the thin member 3 and support the thin member 3. Unlike the case of fixing to the support member, the hardened portion by the adhesive can be eliminated in the thin member 3. At the same time, in the piezoelectric speaker 1 of the present embodiment, the elastic body 4 is provided between the front support 51 and the thin member 3, so that the outer periphery of the thin member 3 is supported by the front support 51 and the rear support. It is possible to prevent the body 52 from being fixed more than necessary. In the thin member 3, the hardened portion by the adhesive and the unnecessary fixing by the front side support body 51 and the rear side support body 52 to the thin member 3 are factors that restrain the vibration of the thin member 3. As a result, the piezoelectric speaker 1 of the present embodiment can reduce the factors that restrain the vibration of the thin member 3 as compared with the case where the thin member is fixed to the support member using an adhesive. 3 can be increased, and the acoustic impedance, that is, the sound pressure in a wide frequency band (low range and resonance point) can be increased.

  Further, in the piezoelectric speaker 1 of the present embodiment, the front support 51 and the rear support 52 of the support member 5 are detachable, and the front support 51 and the rear support 52 are fixed in position. Since the thin member 3 is sometimes supported, the thin member 3 can be easily attached to and detached from the support member 5 as compared with the case where the thin member is fixed to the support member using an adhesive.

  Moreover, the piezoelectric speaker 1 of this embodiment can increase the amplitude at the time of vibration of the thin member 3 because the elastic body 4 is a thermoplastic elastomer, and can be used in a wide frequency band (low range and resonance point). The acoustic impedance, that is, the sound pressure can be reliably increased with a simple configuration.

  Further, the piezoelectric speaker 1 of the present embodiment has a structure in which the front side support 51 and the elastic body 4 are integrated by the front side support 51 and the elastic body 4 being a thermoplastic material and simultaneously molded. Can be realized. Thereby, according to the piezoelectric speaker 1 of this embodiment, the manufacturing process (an assembly process is included) of the support member 5 and the elastic body 4 can be simplified.

  Moreover, the piezoelectric speaker 1 of this embodiment can reduce the cost of the thin member 3 and can improve the reliability (heat resistance) of the thin member 3 because the thin member 3 is a plastic film.

  As a modification of the present embodiment, the elastic body 4 may be provided not between the front support 51 and the thin member 3 but between the rear support 52 and the thin member 3. The piezoelectric speaker 1 of this modified example realizes a structure in which the rear surface side support body 52 and the elastic body 4 are integrated by simultaneously molding the rear surface side support body 52 and the elastic body 4 with a thermoplastic material. can do. Thereby, according to the piezoelectric speaker 1 of this modification, the manufacturing process (including the assembly process) of the support member 5 and the elastic body 4 can be simplified as in the case of the piezoelectric speaker 1 of the present embodiment. . In the case of this modification, the rear surface side support body 52 corresponds to the first support body of the present invention, and the front surface side support body 51 corresponds to the second support body of the present invention.

  Further, the elastic body 4 may be provided between both the front side support body 51 and the thin member 3 and between the rear side support body 52 and the thin member 3. That is, the piezoelectric speaker 1 may be provided with two elastic bodies 4. In the piezoelectric speaker 1 in this case, the front support 51, the rear support 52, and the elastic body 4 are thermoplastic materials, and the front support 51 and the one elastic body 4 are simultaneously molded, The side support body 52 and the other elastic body 4 are simultaneously molded, so that the front side support body 51 and the one elastic body 4 are integrated, and the rear side support body 52 and the other elastic body 4 are combined. An integrated structure can be realized. Thereby, according to the said piezoelectric speaker 1, the manufacturing process (an assembly process is included) of the support member 5 and the elastic body 4 can be simplified like the case of the piezoelectric speaker 1 of this embodiment.

  As another modification of the present embodiment, the elastic body 4 may be a polyurethane foam instead of the elastomer. Also in this modified example, as in the present embodiment, the piezoelectric speaker 1 can further increase the amplitude of the thin member 3 during vibration, and acoustic impedance, that is, sound in a wide frequency band (low range and resonance point). The pressure can be reliably increased with a simple configuration.

  As a modification of the present embodiment, the thin member 3 may be a resin film (circular resin film) formed in a disk shape as shown in FIG. Also in this modified example, as in the present embodiment, the thin member 3 is provided around the piezoelectric vibrator 2 in combination with the diaphragm 22 (see FIG. 3B).

  As another modification of the present embodiment, a corrugation 31 may be provided on the thin member 3 as shown in FIG.

  The thin member 3 may be paper made of wood pulp as a raw material instead of a resin film, or paper made of a non-wood plant such as mulberry, mitsumata or bamboo. The thin member 3 may be a non-woven fabric or a material obtained by impregnating a non-woven fabric with an adhesive to give rigidity. Furthermore, the thin member 3 may be a material obtained by applying a urethane coat to polyester, or may be titanium, aluminum, or the like.

  As a modification of the present embodiment, a configuration in which a recess is formed in the front support 51 and a protrusion is provided in the rear support 52 may be employed. In the case of this modification, the front side support body 51 and the rear side support body 52 are fitted together by the protrusion of the rear side support body 52 entering the recess of the front side support body 51.

  Further, the front support 51 and the rear support 52 do not support the thin member 3 by sandwiching the entire outer peripheral portion of the thin member 3, but are thin by sandwiching a part of the outer peripheral portion of the thin member 3. The member 3 may be supported. For example, the front side support body 51 and the rear side support body 52 may sandwich the outer peripheral portion of the thin member 3 at positions (two points) facing each other across the center of the thin member 3, or the outer periphery of the thin member 3. The outer peripheral portion of the thin member 3 may be sandwiched at positions (three points) separated every 120 ° in the direction, or the thin member 3 may be sandwiched at positions (four points) separated every 90 ° in the outer peripheral direction of the thin member 3. You may clamp the outer peripheral part. In this case, as the elastic body 4, a member corresponding to the size of the clamping position may be used instead of the annular member. In addition, the number of positions where the front side support body 51 and the rear side support body 52 sandwich the thin member 3 is not limited to 2 to 4 points, and may be 5 points or more.

(Embodiment 2)
In the second embodiment, a smoke detector 6 using the piezoelectric speaker 1 of the first embodiment will be described as shown in FIG. The smoke detector 6 of the present embodiment is, for example, a house fire alarm (house fire alarm) attached to a house or the like. When a fire occurs, the smoke detector 6 detects smoke and outputs a sound, and is a fire. The resident can be notified. The smoke detector 6 corresponds to the alarm device of the present invention.

  Since the smoke detector 6 is attached to a room, bedroom, stairs, hallway, etc. in a house, a compact size and a thin size are required so that the installation location is not limited and the interior design is not disturbed. Yes. Therefore, the smoke detector 6 is preferably a device incorporating the piezoelectric speaker 1 that is smaller than the dynamic speaker.

  The smoke detector 6 includes a smoke detector 61, a substrate circuit 62, a housing 63, and a base 64 together with the piezoelectric speaker 1.

  The smoke detection unit 61 optically detects smoke using a light emitting unit and a light receiving unit (not shown). The smoke sensing unit 61 includes an optical base 611 in which the light emitting unit and the light receiving unit are accommodated. The optical base 611 has a plurality of labyrinth walls, each of which is a bent wall, and is covered with an insect net 612. Each labyrinth wall is provided to prevent external light from entering the optical base 611. The insect net 612 is formed in a cylindrical shape that matches the outer shape of the optical base 611. The light emitting unit and the light receiving unit are mounted on the substrate circuit 62. The light emitting unit is provided with an LED as a light source, and the light receiving unit is provided with a photodiode as a light receiving element that receives light from the light emitting unit. The light emitting unit and the light receiving unit are accommodated in the optical base 611 when the substrate circuit 62 is attached to the optical base 611. At this time, the light receiving unit is disposed in the optical base 611 at a position off the optical axis of the light from the light emitting unit. That is, the light receiving part is not arranged on the optical axis of the light from the light emitting part. Moreover, since external light does not penetrate | invade by each labyrinth wall of the optical base 611, a light-receiving part does not receive external light.

  In the smoke detecting unit 61 having the above structure, when no smoke is present inside the optical base 611, light from the light emitting unit is not received by the light receiving unit. On the other hand, when smoke is present inside the optical base 611, in the smoke sensing unit 61, light from the light emitting unit is scattered by the smoke, and the light receiving unit receives the scattered light. That is, the smoke detector 61 detects smoke when light is received by the light receiver.

  The substrate circuit 62 includes a mounting substrate 621. The mounting substrate 621 includes a determination unit (not shown) for determining that a fire has occurred when the amount of light received by the light receiving unit of the smoke sensing unit 61 is equal to or greater than a threshold value, and for vibrating the piezoelectric speaker 1. The signal output unit (not shown) is mounted. When the smoke detector 61 detects smoke, the signal output unit outputs an electrical signal to the piezoelectric speaker 1 so that a sound for notifying that there is a fire is output from the piezoelectric speaker 1. In addition, a button 622 is provided on the mounting substrate 621. The front portion 623 of the button 622 is exposed to the outside from the opening 665 of the cover 66 when the cover 66 is attached to a body 65 (described later) in which the substrate circuit 62 is accommodated. When the front portion 623 of the button 622 exposed to the outside is pressed, the sound from the piezoelectric speaker 1 stops. The determination unit and the smoke detection unit 61 of the substrate circuit 62 correspond to the sensor of the present invention.

  The housing 63 is attached to the body 65 in which the smoke detection unit 61 and the board circuit 62 are accommodated, the cover 66 attached to the front side of the body 65 (upper side in FIG. 8), and the rear side (lower side in FIG. 8) of the body 65. The back cover 67 is provided. The body 65, the cover 66, and the back cover 67 are members formed of flame retardant ABS resin. The housing 63 accommodates the smoke detector 61 and the board circuit 62.

  The body 65 includes a disk-shaped bottom surface portion 651. A cylindrical rib protrudes from the bottom surface portion 651 in the front surface direction (upward in FIG. 8) and is provided as the rear surface side support 52. In the present embodiment, the rear support 52 is provided integrally with the body 65. The bottom surface portion 651 is formed with an opening 653 to which the insect net 612 is attached and an opening 654 into which a battery storage portion 672 described later is inserted. A cylindrical side surface portion 652 protruding in the vertical direction is provided integrally with the bottom surface portion 651 from the outer peripheral portion of the bottom surface portion 651. A plurality of opening windows 655, 655... Are formed on the side surface portion 652. The plurality of open windows 655, 655,... Are partitioned by a plurality of window frames that are framed in a lattice shape in order to allow smoke to flow into the smoke sensing unit 61.

  The cover 66 includes a curved front surface portion 661. The front surface portion 661 is integrally provided with a cylindrical side surface portion 662 that protrudes downward from the outer peripheral portion of the front surface portion 661. Further, the front surface portion 661 has a region 664 in which a plurality of sound holes 663, 663... Are formed. On the back surface of the front surface portion 661, a cylindrical rib protrudes from the periphery of the region 664 in the rear surface direction (downward in FIG. 8) and is provided as the front surface side support 51. In the present embodiment, the front side support body 51 is provided integrally with the body 66. When the cover 66 is attached to the body 65, the front side support body 51 and the rear side support body 52 are fixed in position in a state where the thin member 3 is sandwiched and fitted. In addition, an opening 665 for exposing the front surface portion 623 of the button 622 is formed in the front surface portion 661.

  The back cover 67 includes a disk-shaped bottom surface portion 671. The bottom surface portion 671 is provided with a battery storage portion 672 in which the battery 7 is stored. After the back cover 67 is attached to the body 65, the battery 7 is stored in the battery storage portion 672 from the outside (the lower side in FIG. 8). The battery 7 stored in the battery storage unit 672 is electrically connected to the substrate circuit 62.

  The base 64 is a member used for attachment to a to-be-attached part (not shown). Examples of attached parts include living rooms, bedrooms, stairs, and corridors. The base 64 is engaged with the housing 63 after being attached to the attached portion. Thereby, the smoke detector 6 is installed in a to-be-attached part.

  The piezoelectric speaker 1 of the present embodiment converts an electrical signal output from a signal output unit (not shown) of the board circuit 62 into sound when smoke is detected by the smoke detection unit 61 in the event of a fire, which is called fire. A sound for notifying an abnormal state is output. Sounds output from the piezoelectric speaker 1 for notifying an abnormal state include an alarm sound and an alarm sound. The alarm sound output from the piezoelectric speaker 1 includes, for example, a sound “view, view, view”. The alarm sound output from the piezoelectric speaker 1 includes, for example, a sound “fire”. Residents can be informed of the occurrence of a fire by the above warning sound and warning sound. The piezoelectric speaker 1 outputs a notification sound “battery is exhausted” when the remaining amount of the battery 7 is low.

  As a modification of the present embodiment, instead of the piezoelectric speaker 1 of the first embodiment, the piezoelectric speaker 1 of the modification of the first embodiment may be used for the smoke detector 6.

  Further, the piezoelectric speaker 1 of the first embodiment (including the piezoelectric speaker 1 of the modification of the first embodiment) may be used for other alarm devices other than the smoke detector 6. Other alarm devices include a crime prevention device (intrusion detection siren) that outputs an alarm sound when a suspicious person's intrusion is detected.

  Furthermore, the piezoelectric speaker 1 according to the first embodiment (including the piezoelectric speaker 1 according to the modification of the first embodiment) may be used for other electrical devices other than the alarm device. Examples of other electrical devices include acoustic devices, electronic musical instruments, home appliances, in-vehicle devices, and communication devices (including telephones).

(Embodiment 3)
The piezoelectric speaker 1 according to the third embodiment is that the frequency ratio between the resonance frequency of the piezoelectric vibrator 2 and the resonance frequency of the thin member 3 is within a predetermined range including 1: 1. Is different. Hereinafter, the piezoelectric speaker 1 of this embodiment will be described with reference to FIGS. In addition, about the component similar to the piezoelectric speaker 1 of Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As with the thin member 3 of the first embodiment, the thin member 3 of the present embodiment has a circular shape (annular shape) as viewed from the thickness direction (a shape in plan view). In addition, the thin member 3 of this embodiment may be a disk shape as shown in FIG.

  In FIG. 9, the maximum value of the sound pressure level of the piezoelectric speaker 1 with respect to the diameter ratio (size ratio) (φ2 / φ1) (see FIG. 10) of the diameter φ1 of the piezoelectric vibrator 2 and the diameter φ2 of the thin member 3 (see FIG. 10). "Peak sound pressure"). When the diameter ratio (φ2 / φ1) between the piezoelectric vibrator 2 and the thin member 3 changes, the relationship between the resonance frequency of the piezoelectric vibrator 2 and the resonance frequency of the thin member 3 changes, as shown in FIG. The sound pressure level of the piezoelectric speaker 1 changes. In the characteristics shown in FIG. 9, the diameter ratio of the piezoelectric vibrator 2 to the thin member 3 (φ2 / 1 /) is changed by making the diameter of the piezoelectric vibrator 2 constant at 31 mm and changing the diameter of the thin member 3 from 40 mm to 51.7 mm. φ1) is changed. Further, at each diameter ratio (φ2 / φ1), the mass of the piezoelectric vibrator 2 and the thickness of the thin member 3 are optimized so that the sound pressure level is maximized. As a result of measuring the peak sound pressure of each diameter ratio (φ2 / φ1) as described above, the peak sound pressure is maximized when the diameter of the thin member 3 is 47.3 mm. In addition, description is abbreviate | omitted about the function similar to the piezoelectric vibrator 2 and the thin member 3 (refer FIG. 1) of Embodiment 1. FIG.

  The closer the resonance frequency of the piezoelectric vibrator 2 and the resonance frequency of the thin member 3 are, the higher the peak sound pressure of the piezoelectric speaker 1 is. Therefore, the piezoelectric vibrator 2 has a diameter of 31 mm and the thin member 3 has a diameter of 47. When the diameter ratio is 3 mm, that is, when the diameter ratio (φ2 / φ1) is 1.53, the frequency ratio between the resonance frequency of the piezoelectric vibrator 2 and the resonance frequency of the thin member 3 is approximately 1: 1.

  The resonance frequency of the thin member 3 of this embodiment is determined within a predetermined range including a frequency at which the frequency ratio with the resonance frequency of the piezoelectric vibrator 2 is 1: 1. The predetermined range refers to a range in which a sufficiently large value is obtained as the peak sound pressure of the piezoelectric speaker 1, and specifically refers to a range in which the peak sound pressure is 95% or more with respect to the maximum value. The predetermined range is a range where the diameter ratio (φ2 / φ1) is 1.45 or more and 1.62 or less in relation to the diameter ratio (φ2 / φ1) between the piezoelectric vibrator 2 and the thin member 3. It is preferable. A more preferable range is a diameter ratio (φ2 / φ1) of 1.48 or more and 1.6 or less. A more preferable range is a diameter ratio (φ2 / φ1) of 1.5 or more and 1.55 or less. Note that the piezoelectric speaker 1 can be made smaller by making the actual diameter ratio (φ2 / φ1) smaller than the diameter ratio (φ2 / φ1) that is the maximum value of the peak sound pressure, rather than increasing it.

  As described above, according to the piezoelectric speaker 1 of the present embodiment, the resonance frequency of the thin member 3 is determined within a predetermined range including a frequency in which the frequency ratio with the resonance frequency of the piezoelectric vibrator 2 is 1: 1. Accordingly, the sound pressure level of the piezoelectric speaker 1 can be increased as compared with the case where the frequency ratio between the resonance frequency of the piezoelectric vibrator 2 and the resonance frequency of the thin member 3 is a frequency ratio other than the above.

(Embodiment 4)
As shown in FIG. 11, the piezoelectric speaker 1 according to the fourth embodiment is a piezoelectric speaker according to the third embodiment in that the sandwiching surfaces 513 and 524 of the front support 51 and the rear support 52 are formed in a tapered shape. Different from the speaker 1. Hereinafter, the piezoelectric speaker 1 of the present embodiment will be described with reference to FIG. In addition, about the component similar to the piezoelectric speaker 1 of Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The front side support body 51 and the rear side support body 52 of the present embodiment have clamping surfaces 513 and 524 that clamp the outer peripheral portion of the thin member 3. The clamping surface 513 of the front side support body 51 and the clamping surface 524 of the rear side support body 52 are inclined and formed in a tapered shape. That is, the sandwiching surface 513 that is inclined from the outer peripheral side of the thin member 3 toward the center side at the portion where the front support 51 and the rear support 52 are fitted to the front support 51 and the rear support 52. , 524 are formed. The inclination angle (taper angle) θ1 from the horizontal plane is preferably 2 ° to 10 °. A more preferable range is 2 ° to 4 °.

  The thin member 3 of the present embodiment has a direction opposite to the sound output direction (see FIG. 11) when the direction in which the sound generated by the vibration of the piezoelectric vibrator 2 and the thin member 3 is extracted is the sound output direction (downward in FIG. 11). 11 is projected between the front side support body 51 and the rear side support body 52. That is, since the thin member 3 is clamped together with the elastic body 4 by the tapered clamping surface 513 of the front support 51 and the tapered clamping surface 524 of the rear support 52, the thin member 3 is directed from the outer periphery toward the center. It becomes a so-called cone shape that is inclined. In the present embodiment, the thin member 3 protrudes in the direction opposite to the surface on which the piezoelectric body 21 is provided on the vibration plate 22 (upward in FIG. 11) to the front support 51 and the rear support 52. It is pinched.

  As described above, according to the piezoelectric speaker 1 of the present embodiment, the thin member 3 is formed in a cone shape by forming the tapered sandwiching surfaces 513 and 524 on the front support 51 and the rear support 52. be able to. Thereby, the piezoelectric speaker 1 of this embodiment can raise the sound pressure level of the piezoelectric speaker 1 compared with the case where the thin member 3 is a plane.

  Further, in the piezoelectric speaker 1 of the present embodiment, as described above, tapered sandwiching surfaces 513 and 524 are formed on the front support 51 and the rear support 52, and the thin member 3 is formed in a cone shape. Thus, the distortion of the thin member 3 after continuous driving can be reduced.

  Furthermore, according to the piezoelectric speaker 1 of the present embodiment, the thin member 3 protrudes in the direction opposite to the surface on which the piezoelectric body 21 is provided on the diaphragm 22 (upward direction in FIG. 11), thereby reducing the thickness. The sound pressure level of the piezoelectric speaker 1 can be increased as compared with the case where the member 3 projects in the direction of the surface of the diaphragm 22 where the piezoelectric body 21 is provided (the lower direction in FIG. 11).

(Embodiment 5)
The piezoelectric speaker 1 according to the fifth embodiment is different from the piezoelectric speaker 1 according to the first embodiment in that the thin member 3 includes protrusions 32 and 33 as shown in FIG. Hereinafter, the piezoelectric speaker 1 of the present embodiment will be described with reference to FIG. In addition, about the component similar to the piezoelectric speaker 1 of Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The thin member 3 according to the present embodiment includes protrusions 32 and 33 at a portion sandwiched between the front support 51 and the rear support 52. The protrusion 32 is provided on a surface (the lower surface in FIG. 12) that faces the front support 51, and the protrusion 33 is provided on a surface (the upper surface in FIG. 12) that faces the rear support 52. The protrusions 32 and 33 are made of the same material as other portions of the thin member 3. In addition, description is abbreviate | omitted about the function similar to the thin member 3 of Embodiment 1. FIG.

  The tip surfaces of the protrusions 32 and 33 are inclined with respect to the inner surfaces 34 and 35 of the thin member 3. As a result, the thin member 3 has a so-called cone shape that is inclined from the outer peripheral side toward the center side when sandwiched between the front side support body 51 and the rear side support body 52. The inclination angle θ2 from the horizontal plane is preferably 2 ° to 10 °. A more preferable range is 2 ° to 4 °.

  In the present embodiment, the thin member 3 protrudes in the direction opposite to the surface on which the piezoelectric body 21 is provided on the vibration plate 22 (upward in FIG. 12), and forms the front side support body 51 and the rear side support body 52. It is pinched.

  FIG. 13 shows the sound pressure level characteristic (solid line in FIG. 13) of the sound output from the piezoelectric speaker 1 of the present embodiment. The sound pressure level characteristic of FIG. 13 is a result when a predetermined voltage is applied to the piezoelectric speaker 1 and the sound pressure level at the front position of the piezoelectric speaker 1 is measured. The inclination angle θ2 is 2 ° to 4 °. FIG. 13 also shows, as a comparative example, the sound pressure level characteristic (broken line in FIG. 13) of the sound output from the piezoelectric speaker configured such that the thin member 3 does not tilt (tilt angle θ2 is 0 °). . As shown in FIG. 13, the piezoelectric speaker 1 of this embodiment has a maximum sound pressure level between 2000 and 3000 Hz higher than that of the piezoelectric speaker of the comparative example.

  As described above, the piezoelectric speaker 1 of the present embodiment includes the protrusions 32 and 33 whose tip surfaces are inclined with respect to the inner surfaces 34 and 35 on the thin member 3, and the portion where the protrusions 32 and 33 are provided is on the front side. By sandwiching the support 51 and the rear support 52, the thin member 3 can be formed into a cone shape. Thereby, the piezoelectric speaker 1 of this embodiment can raise the sound pressure level of the piezoelectric speaker 1 compared with the case where the thin member 3 is a plane.

(Embodiment 6)
As shown in FIG. 14, the piezoelectric speaker 1 according to the sixth embodiment is such that the sandwiching surfaces 513 and 524 of the front support 51 and the rear support 52 are formed to be uneven. 1 and different. Hereinafter, the piezoelectric speaker 1 of the present embodiment will be described with reference to FIG. In addition, about the component similar to the piezoelectric speaker 1 of Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The front surface side support body 51 and the rear surface side support body 52 of the present embodiment include sandwiching surfaces 513 and 524 that sandwich the outer peripheral portion of the thin member 3. Convex portions 513 and 525 are formed at positions where the sandwiching surface 513 of the front support 51 and the sandwiching surface 524 of the rear support 52 do not overlap each other. That is, the front-side support 51 and the rear-side support 52 are fitted to each other so that the thin member 3 sandwiched between the front-side support 51 and the rear-side support 52 is inclined from the outer peripheral side toward the center. Are formed in unevenness different from each other in the direction connecting the center and the outer periphery of the thin member 3. The convex portions 514 and 525 are members formed by an elastomer. By forming the convex portion 514 of the front surface side support body 51 on the inner side as compared with the convex portion 525 of the rear surface side support body 52, the thin member 3 can be protruded rearward (upward in FIG. 14B). it can.

  The thin member 3 of the present embodiment has an outer peripheral side when it is sandwiched between the front support 51 and the rear support 52 by the convex 514 of the front support 51 and the convex 525 of the rear support 52. It becomes what is called a cone shape which inclines toward the center side. The inclination angle θ3 from the horizontal plane is preferably 2 ° to 10 °. A more preferable range is 2 ° to 4 °. In the present embodiment, the thin member 3 protrudes in the direction opposite to the surface on which the piezoelectric body 21 is provided on the diaphragm 22 (upward in FIG. 14B), and supports the front side support 51 and the rear side support. It is clamped by the body 52. In addition, description is abbreviate | omitted about the function similar to the thin member 3 of Embodiment 1. FIG.

  As described above, according to the piezoelectric speaker 1 of the present embodiment, the thin member 3 is sandwiched between the sandwiching surface 513 on which the convex portion 514 is formed and the sandwiching surface 524 on which the convex portion 525 is formed. Since the shape of the mold can be facilitated, the sound pressure level of the piezoelectric speaker 1 can be easily increased.

  Note that the thin member 3 may have an elliptical shape as viewed from the thickness direction (for example, the upward direction in FIGS. 11, 12, and 14).

  In the piezoelectric speakers 1 of the fourth to sixth embodiments, similarly to the piezoelectric speaker 1 of the third embodiment, the resonance frequency of the thin member 3 includes a frequency whose frequency ratio with the resonance frequency of the piezoelectric vibrator 2 is 1: 1. It may be within a predetermined range.

  The elastic bodies 4 of Embodiments 4 to 6 may be provided between the front support 51 and the thin member 3 instead of between the rear support 52 and the thin member 3. In this case, the front side support body 51 corresponds to a first support body, and the rear side support body 52 corresponds to a second support body.

  The thin member 3 of Embodiments 3 to 6 may have a corrugation 31 as shown in FIG. The configuration in which the thin member 3 has the corrugation 31 as shown in FIG. 7 can make the sound pressure higher than the configuration in which the thin member 3 does not have the corrugation 31.

  The piezoelectric speakers 1 of the third to sixth embodiments may be used for the smoke detector 6 as in the second embodiment, or may be used for an alarm device other than the smoke detector 6. As another alarm device, there is a crime prevention device that outputs an alarm sound when the intrusion of a suspicious person is detected. Moreover, you may use the piezoelectric speaker 1 of Embodiment 3-6 for electric devices other than an alarm device. Examples of other electrical devices include acoustic devices, electronic musical instruments, home appliances, in-vehicle devices, and communication devices.

DESCRIPTION OF SYMBOLS 1 Piezoelectric speaker 2 Piezoelectric vibrator 21 Piezoelectric body 22 Diaphragm 3 Thin member 4 Elastic body 5 Support member 51 Front side support body (1st support body)
52 Rear side support (second support)
6 Smoke detector (alarm device)
61 Smoke detector (sensor)
62 Substrate circuit (sensor, signal output unit)
63 Housing

Claims (12)

A piezoelectric vibrator having a piezoelectric body made of a piezoelectric element and a diaphragm that vibrates by deformation of the piezoelectric body;
A thin member provided at least around the piezoelectric vibrator in combination with the diaphragm;
A first support and a second support that are fixed in a state of being fitted to each other, and the first support when the first support and the second support are fixed in position; A support member for supporting the thin member by sandwiching the outer peripheral portion of the thin member at a portion where the body and the second support member are fitted to each other;
An elastic body provided between the first support and the thin member;
The thin member has a sound output direction as a direction in which sound generated by the vibration of the piezoelectric vibrator is extracted, protrudes in a direction opposite to the sound output direction, and is sandwiched between the first support body and the second support body. And
The first support body and the second support body have a sandwiching surface for sandwiching an outer peripheral portion of the thin member, and the sandwiching surface of the first support body and the sandwiching of the second support body The surface is inclined and tapered,
Inclination angle of the thin thickness member with respect to the plane of the of the first support and the second support is perpendicular to the direction in which the opposing, Ri 2 ° to 10 ° der,
The piezoelectric vibrator and the thin member are circular when viewed from the thickness direction,
A ratio of an outer diameter of the thin member to a diameter of the piezoelectric vibrator is 1.45 or more and 1.62 or less . A piezoelectric vibrator having a piezoelectric body made of a piezoelectric element and a diaphragm that vibrates by deformation of the piezoelectric body;
A thin member provided at least around the piezoelectric vibrator in combination with the diaphragm;
A first support and a second support that are fixed in a state of being fitted to each other, and the first support when the first support and the second support are fixed in position; A support member for supporting the thin member by sandwiching the outer peripheral portion of the thin member at a portion where the body and the second support member are fitted to each other;
An elastic body provided between the first support and the thin member;
The thin member has a sound output direction as a direction in which sound generated by the vibration of the piezoelectric vibrator is extracted, protrudes in a direction opposite to the sound output direction, and is sandwiched between the first support body and the second support body. And
The thin member has a protrusion at a portion sandwiched between the first support and the second support, and a tip end surface of the protrusion is inclined with respect to an inner surface of the thin member. ,
Inclination angle of the thin thickness member with respect to the plane of the of the first support and the second support is perpendicular to the direction in which the opposing, Ri 2 ° to 10 ° der,
The piezoelectric vibrator and the thin member are circular when viewed from the thickness direction,
A ratio of an outer diameter of the thin member to a diameter of the piezoelectric vibrator is 1.45 or more and 1.62 or less . A piezoelectric vibrator having a piezoelectric body made of a piezoelectric element and a diaphragm that vibrates by deformation of the piezoelectric body;
A thin member provided at least around the piezoelectric vibrator in combination with the diaphragm;
A first support and a second support that are fixed in a state of being fitted to each other, and the first support when the first support and the second support are fixed in position; A support member for supporting the thin member by sandwiching the outer peripheral portion of the thin member at a portion where the body and the second support member are fitted to each other;
An elastic body provided between the first support and the thin member;
The thin member has a sound output direction as a direction in which sound generated by the vibration of the piezoelectric vibrator is extracted, protrudes in a direction opposite to the sound output direction, and is sandwiched between the first support body and the second support body. And
The first support body and the second support body have a sandwiching surface for sandwiching an outer peripheral portion of the thin member, and the sandwiching surface of the first support body and the sandwiching of the second support body The surface is formed with convex portions at positions that do not overlap each other in the direction connecting the center and the outer periphery of the thin member,
Inclination angle of the thin thickness member with respect to the plane of the of the first support and the second support is perpendicular to the direction in which the opposing, Ri 2 ° to 10 ° der,
The piezoelectric vibrator and the thin member are circular when viewed from the thickness direction,
A ratio of an outer diameter of the thin member to a diameter of the piezoelectric vibrator is 1.45 or more and 1.62 or less .   The piezoelectric speaker according to claim 1, wherein the inclination angle is 2 ° to 4 °.   The thin member protrudes in a direction opposite to a surface of the diaphragm on which the piezoelectric body is provided, and is sandwiched between the first support body and the second support body. The piezoelectric speaker according to any one of 1 to 4.   The piezoelectric speaker according to claim 1, wherein the elastic body is a thermoplastic elastomer.   The piezoelectric speaker according to claim 6, wherein the first support is made of a thermoplastic material and is formed simultaneously with the elastic body.   The piezoelectric speaker according to claim 1, wherein the elastic body is a polyurethane foam.   The piezoelectric speaker according to claim 1, wherein the thin member is a plastic film.   The resonance frequency of the thin member is determined within a predetermined range including a frequency at which a ratio with the resonance frequency of the piezoelectric vibrator is 1: 1. The piezoelectric speaker according to item. The piezoelectric speaker according to any one of claims 1 to 10, wherein the thin member has a corrugation formed of at least one of a peak portion and a valley portion formed in an annular shape . The piezoelectric speaker according to any one of claims 1 to 11,
A sensor for detecting surrounding abnormalities;
A signal output unit that outputs an electrical signal to notify the surrounding abnormality when the surrounding abnormality is detected by the sensor;
A housing in which the piezoelectric speaker, the sensor, and the signal output unit are housed and the support member is integrally provided;
Alarm device, characterized in that it comprises a.

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