Audio devices

Abstract

To provide an acoustic device capable of increasing sound pressure in a low frequency region.SOLUTION: An acoustic device 1 includes a piezoelectric vibrator 2, a cylindrical member 3 having a first end 3a closed by the piezoelectric vibrator 2 and a second end 3b open, and a joining member 4 joining the piezoelectric vibrator 2 and the first end 3a.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an acoustic device.

Background Art

[0002] There is known a speaker called a tweeter configured to drive by attaching a diaphragm such as a cone type to a piezoelectric element (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the acoustic device using the above piezoelectric element, the sound pressure in the low frequency range is not sufficient.

[0005] One aspect of the present disclosure provides an acoustic device capable of increasing the sound pressure in the low frequency range.

Means for Solving the Problems

[0006] An acoustic device according to one aspect of the present disclosure includes a cylindrical member having a piezoelectric vibrator, a first end closed by the piezoelectric vibrator, and an open second end, and a first joining member joining the piezoelectric vibrator and the first end.

[0007] In the above acoustic device, since the piezoelectric vibrator is joined to the first end of the cylindrical member and closes the first end, the sound pressure in the low frequency range can be increased.

[0008] The first joining member may be softer than the cylindrical member. In this case, it becomes difficult for high frequency components to be transmitted from the piezoelectric vibrator to the cylindrical member by the first joining member. Therefore, the sound pressure in the low frequency range is likely to increase.

[0009] A piezoelectric vibrator may include a diaphragm that closes the first end, a piezoelectric element placed on the diaphragm, and a second connecting member that joins the diaphragm and the piezoelectric element. In this case, the diaphragm can increase the sound pressure of the piezoelectric element.

[0010] The second bonding member may be softer than the diaphragm. In this case, the second bonding member makes it more difficult for high-frequency components to be transmitted from the piezoelectric element to the diaphragm. Therefore, the sound pressure in the low-frequency range tends to increase.

[0011] The first joining member may be thicker than the piezoelectric element. In this case, high-frequency components become even less likely to be transmitted from the piezoelectric vibrator to the cylindrical member.

[0012] The second joining member may be thicker than the piezoelectric element. In this case, high-frequency components will be even less likely to be transmitted from the piezoelectric element to the diaphragm.

[0013] The diaphragm has a first surface facing the first end and a second surface opposite to the first surface, and the piezoelectric element may be bonded to the second surface. In this case, since the second surface of the diaphragm on which the piezoelectric element is provided faces outward from the cylindrical member, the piezoelectric element can be easily positioned.

[0014] The diaphragm has a first surface facing the first end and a second surface opposite to the first surface, and the piezoelectric element may be bonded to the first surface. In this case, the first surface of the diaphragm on which the piezoelectric element is provided faces inward towards the cylindrical member, so the piezoelectric element is less susceptible to external shocks.

[0015] The axial length of the cylindrical member may be longer than the maximum length of the second end. In this case, high-frequency components can be suppressed.

[0016] The first and second ends may have the same shape. In this case, it is possible to prevent the sound device from becoming too large. [Effects of the Invention]

[0017] According to one aspect of the present invention, there is provided an acoustic device capable of increasing the sound pressure in the low-frequency range.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a perspective view showing an acoustic device according to the first embodiment. [Figure 2] FIG. 2 is a perspective view showing a partially enlarged view of the acoustic device of FIG. 1. [Figure 3] FIG. 3 is an exploded perspective view of the acoustic device of FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view of the acoustic device of FIG. 1. [Figure 5] FIG. 5 is a perspective view showing an acoustic device according to the second embodiment. [Figure 6] FIG. 6 is a perspective view showing a partially enlarged view of the acoustic device of FIG. 5. [Figure 7] FIG. 7 is a perspective view showing a partially enlarged view of the acoustic device of FIG. 5. [Figure 8] FIG. 8 is an exploded perspective view showing the piezoelectric element of FIG. 5. [Figure 9] FIG. 9 is a cross-sectional view of the acoustic device of FIG. 4.

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0020] [First Embodiment] The acoustic device 1 according to the first embodiment shown in FIGS. 1 to 4 includes a piezoelectric vibrator 2, a cylindrical member 3, and a joining member 4. The acoustic device 1 is a piezoelectric speaker. The piezoelectric vibrator 2 has a diaphragm 10, a piezoelectric element 11, a joining member 12, and a wiring portion 13. These members constituting the piezoelectric vibrator 2 will be described later.

[0021] The cylindrical member 3 is composed of side walls extending in the axial direction D. The cylindrical member 3 has a first end 3a and a second end 3b in the axial direction D. The first end 3a is closed by the diaphragm 10 of the piezoelectric vibrator 2. The first end 3a has a shape that conforms to the outer shape of the diaphragm 10 of the piezoelectric vibrator 2. Viewed from the axial direction D, the outer shape of the first end 3a matches the outer shape of the diaphragm 10. The second end 3b is open. In other words, the cylindrical member 3 has an opening at the second end 3b. The cross-sectional shape of the cylindrical member 3 is the same throughout the axial direction D. The first end 3a and the second end 3b have the same shape as each other. In this embodiment, the cylindrical member 3 has a cylindrical shape. That is, the cross-sectional shape of the cylindrical member 3 has a circular outer shape.

[0022] The axial length L1 of the cylindrical member 3 is longer than the maximum length L2 of the second end 3b. The maximum length L2 is the maximum length of the outer shape of the second end 3b. In this embodiment, since the outer shape of the second end 3b is circular, the maximum length L2 is the diameter of the outer shape of the second end 3b. If the outer shape of the second end 3b is rectangular, the maximum length L2 is the length of the diagonal of the outer shape of the second end 3b. If the outer shape of the second end 3b is elliptical, the maximum length L2 is the length of the major axis of the outer shape of the second end 3b. The length L1 is configured to be adjustable by the length of the resonance point. By adjusting the length L1, the sound pressure in any frequency range can be increased.

[0023] Length L1 is longer than the maximum length of the first end 3a. In this embodiment, the maximum length of the first end 3a is equal to the maximum length L2 of the second end 3b. Length L1 is between 50 mm and 3000 mm, for example, 2000 mm. Maximum length L2 is between 70 mm and 200 mm, for example, 114 mm. The thickness of the cylindrical member 3 is between 0.5 mm and 5 mm, for example, 3.1 mm. The cylindrical member 3 is made of a resin material such as polyvinyl chloride or polycarbonate. The cylindrical member 3 may also be made of a metal material such as aluminum or stainless steel.

[0024] The joining member 4 connects the piezoelectric vibrator 2 to the first end 3a. The joining member 4 has the same width as the first end 3a and is provided along the outer edge of the piezoelectric vibrator 2. The joining member 4 has a frame shape. The joining member 4 is made of a material that is softer than the cylindrical member 3 and has cushioning properties. The softness of each member can be evaluated, for example, by Young's modulus. The joining member 4 functions as a sound-absorbing member that absorbs sound in the high-frequency range in particular. The thickness of the joining member 4 (the length D in the axial direction of the joining member 4) is greater than the thickness of the piezoelectric element 11 (the length D in the axial direction of the piezoelectric element 11). The joining member 4 is, for example, an adhesive tape. The joining member 4 may also be an elastic adhesive (an adhesive that becomes a rubbery elastic body after curing).

[0025] The diaphragm 10 closes the first end 3a of the cylindrical member 3. The diaphragm 10 has a first surface 10a and a second surface 10b. The first surface 10a faces the first end 3a of the cylindrical member 3. The second surface 10b faces the opposite side of the first surface 10a. The first surface 10a and the second surface 10b are perpendicular to the axial direction D. The diaphragm 10 has, for example, a disc shape. The thickness of the diaphragm 10 is 0.1 mm or more and 5 mm or less, for example, 1 mm.

[0026] The diaphragm 10 is made of a resin material such as polycarbonate or acrylic. When the piezoelectric element 11 is of the bimorph type, the diaphragm 10 being made of a resin material prevents the sound from becoming too high-pitched and improves the acoustic characteristics. The diaphragm 10 may also be made of a metal material such as SUS (stainless steel).

[0027] The piezoelectric element 11 is arranged on the diaphragm 10. The piezoelectric element 11 is positioned approximately in the center of the diaphragm 10 when viewed from the axial direction D, and is spaced apart from the cylindrical member 3. In this embodiment, the piezoelectric element 11 is joined to the second surface 10b by a joining member 12. The piezoelectric element 11 has a rectangular plate shape. The piezoelectric element 11 has a main surface 11a facing the second surface 10b, and a main surface 11b opposite to the main surface 11a. The main surfaces 11a and 11b face each other in the thickness direction of the piezoelectric element 11. The main surfaces 11a and 11b are perpendicular to the axial direction D.

[0028] The piezoelectric element 11 is, for example, a bimorph type piezoelectric element. The piezoelectric element 11 may also be a monomorph type piezoelectric element. The piezoelectric element 11 is, for example, a multilayer type piezoelectric element, and includes a plurality of piezoelectric layers stacked in the thickness direction of the piezoelectric element 11. The piezoelectric element 11 vibrates when a voltage is applied.

[0029] The maximum length of the piezoelectric element 11 as viewed from the axial direction D is shorter than the length L1 described above. The maximum length of the piezoelectric element 11 as viewed from the axial direction D is the length of the diagonal of the rectangular main surfaces 11a and 11b. The length of the piezoelectric element 11 (length of the long side of the main surfaces 11a and 11b) is 5 mm or more and 100 mm or less. The width of the piezoelectric element 11 (length of the short side of the main surfaces 11a and 11b) is 5 mm or more and 100 mm or less. The thickness of the piezoelectric element 11 (length of the piezoelectric element 11 in the axial direction D) is 0.5 mm or more and 5 mm or less.

[0030] The joining member 12 joins the second surface 10b of the diaphragm 10 to the main surface 11a of the piezoelectric element 11. The joining member 12 is provided along the outer edge of the main surface 11a. The joining member 12 has a frame shape. The main surface 11a has an outer edge region to which the joining member 12 is joined, and an inner region that faces the second surface 10b through a space. In this embodiment, the vibration of the piezoelectric element 11 is less likely to be inhibited compared to the case where the entire surface of the main surface 11a is joined to the second surface 10b.

[0031] The joining member 12 is made of a material that is softer than the diaphragm 10 and has cushioning properties. The joining member 12 functions as a sound-absorbing member that absorbs sound, especially in the high-frequency range. The thickness of the joining member 12 (the length D in the axial direction of the joining member 12) is greater than the thickness of the piezoelectric element 11 (the length D in the axial direction of the piezoelectric element 11). The joining member 12 is made of a thickness equivalent to that of the joining member 4, but may be made of a different thickness than the joining member 4. The joining member 12 is made of the same material as the joining member 4, but may be made of a different material than the joining member 4. The joining member 12 is, for example, an adhesive tape. The joining member 12 may also be an elastic adhesive (an adhesive that becomes a rubbery elastic body after curing).

[0032] The wiring section 13 electrically connects the external electrodes (not shown) of the piezoelectric element 11 to an external control circuit (not shown) and applies a voltage to the piezoelectric element 11. The wiring section 13 includes a flexible substrate 14, a connector 15, and a pair of lead wires 16. The wiring section 13 is drawn out from the short side to the long side of the main surfaces 11a and 11b, but it may also be drawn out from the long side to the short side of the main surfaces 11a and 11b.

[0033] The flexible substrate 14 is in the form of a plate, sheet, or strip. The flexible substrate 14 is arranged so as to be superimposed on the main surface 11b of the piezoelectric element 11. The flexible substrate 14 is, for example, a flexible printed circuit board (FPC) or a flexible flat cable (FFC). That is, the flexible substrate 14 has a plurality of wirings (not shown). In this embodiment, the flexible substrate 14 has a configuration in which a pair of wirings are provided within a resin sheet made of a resin such as polyimide resin.

[0034] The connector 15 electrically connects a pair of wires on the flexible circuit board 14 to a pair of lead wires 16. The pair of lead wires 16 are electrically connected to an external control circuit.

[0035] As explained above, in the acoustic device 1, the piezoelectric vibrator 2 is joined to the first end 3a of the cylindrical member 3, and the first end 3a is closed, so the sound pressure in the low-frequency range can be increased. The joining member 4 that joins the piezoelectric vibrator 2 to the first end 3a is made of a material softer than the material that makes up the cylindrical member 3. With such a joining member 4, high-frequency components are less likely to be transmitted from the piezoelectric vibrator 2 to the cylindrical member 3. Therefore, in the acoustic device 1, the sound pressure in the low-frequency range is easily increased. The joining member 4 is thicker than the piezoelectric element 11. Therefore, high-frequency components are further less likely to be transmitted from the piezoelectric vibrator 2 to the cylindrical member 3.

[0036] The piezoelectric vibrator 2 has a diaphragm 10 and a piezoelectric element 11 placed on the diaphragm 10. The diaphragm 10 can increase the sound pressure of the piezoelectric element 11. The bonding member 12 that joins the piezoelectric element 11 to the diaphragm 10 is made of a material softer than the material that makes up the diaphragm 10. With such a bonding member 12, high-frequency components are less likely to be transmitted from the piezoelectric element 11 to the diaphragm 10. Therefore, in the acoustic device 1, the sound pressure in the low-frequency range is more likely to increase. The bonding member 12 is thicker than the piezoelectric element 11. Therefore, high-frequency components are further less likely to be transmitted from the piezoelectric element 11 to the diaphragm 10.

[0037] The piezoelectric element 11 is bonded to the second surface 10b of the diaphragm 10. Since the second surface 10b of the diaphragm 10 faces outward from the cylindrical member 3, the piezoelectric element 11 can be easily positioned. In addition, the wiring section 13 can be easily connected to the piezoelectric element 11.

[0038] The axial length D of the cylindrical member 3, L1, is longer than the maximum length L2 of the second end 3b. Therefore, high-frequency components can be suppressed. As a result, the sound pressure in the low-frequency range can be relatively increased.

[0039] The first end 3a and the second end 3b of the cylindrical member 3 have the same shape. Therefore, compared to the case where the cylindrical member 3 has a flared shape and the maximum length L2 of the second end 3b is longer than the maximum length of the first end 3a, it is possible to suppress an increase in the size of the sound device 1.

[0040] [Second Embodiment] The acoustic device 1A according to the second embodiment shown in Figures 5 to 9 will be described, focusing on the differences from acoustic device 1. In acoustic device 1A, the piezoelectric element 11 is joined to the first surface 10a by a joining member 12. The joining member 12 joins the first surface 10a of the diaphragm 10 and the main surface 11a of the piezoelectric element 11. The inner region of the main surface 11a faces the first surface 10a with a space between them. A pair of lead wires 16 are led out onto the second surface 10b of the diaphragm 10 through a pair of insertion holes 10c provided in the diaphragm 10. The flexible substrate 14 and connector 15 are arranged on the first surface 10a.

[0041] In the acoustic device 1A, the piezoelectric vibrator 2 is joined to the first end 3a of the cylindrical member 3, and the first end 3a is closed, so the sound pressure in the low-frequency range can be increased. In the acoustic device 1A, the piezoelectric element 11 is joined to the first surface 10a of the diaphragm 10. Since the first surface 10a of the diaphragm 10 faces inward towards the cylindrical member 3, the piezoelectric element 11 is less susceptible to external shocks.

[0042] While embodiments of the present invention have been described above, the present invention is not necessarily limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0043] In the acoustic device 1,1A, the cylindrical member 3 may have a flared shape, and the maximum length of the cross-sectional shape of the cylindrical member 3 may increase from the first end 3a to the second end 3b. Alternatively, the cylindrical member 3 may have a tapered shape, and the maximum length of the cross-sectional shape of the cylindrical member 3 may decrease from the first end 3a to the second end 3b.

[0044] The cylindrical member 3 is not limited to a cylindrical shape, but may also be a rectangular tube with a polygonal cross-sectional shape. The cylindrical member 3 may have openings other than the second end 3b. That is, openings may be provided in the side walls that make up the cylindrical member 3. This makes it possible to increase the sound pressure of the sound devices 1,1A.

[0045] The above embodiments and modifications may be combined as appropriate. [Explanation of Symbols]

[0046] 1,1A...Acoustic device, 2...Piezoelectric vibrator, 3...Cylindrical member, 3a...First end, 3b...Second end, 4...Jointing member, 10...Diaphragm, 10a...First surface, 10b...Second surface, 11...Piezoelectric element, 12...Jointing member, D...Axial direction.

Claims

1. Piezoelectric vibrator and A cylindrical member having a first end closed by the piezoelectric vibrator and an open second end, The system comprises a first joining member that joins the piezoelectric vibrator and the end face of the first end, The piezoelectric vibrator is, The diaphragm that is blocking the first end, A piezoelectric element arranged on the diaphragm, It has a second joining member that joins the diaphragm and the piezoelectric element, The second joining member is softer than the diaphragm and thicker than the piezoelectric element. The first joining member is thicker than the piezoelectric element. sound equipment.

2. The first joining member is softer than the cylindrical member. The acoustic device according to claim 1.

3. The first joining member is provided with the same width as the end face of the first end, The acoustic device according to claim 1 or 2.

4. The diaphragm has a first surface facing the first end and a second surface opposite to the first surface. The piezoelectric element is bonded to the second surface, The acoustic device according to any one of claims 1 to 3.

5. The diaphragm has a first surface facing the first end and a second surface opposite to the first surface. The piezoelectric element is bonded to the first surface, The acoustic device according to any one of claims 1 to 3.

6. The axial length of the cylindrical member is longer than the maximum length of the second end. The acoustic device according to any one of claims 1 to 5.

7. The first end and the second end have the same shape as each other. The acoustic device according to any one of claims 1 to 6.

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