Glass diaphragm and glass module

Abstract

[Problem] To facilitate the exhibition of desired acoustic characteristics in a glass plate when a piezo actuator vibrates. [Solution] This glass diaphragm 10 has a glass plate 11 and a piezo actuator module 2 fixed to the glass plate, wherein: the piezo actuator module has a first housing, a first vibration control layer 35, a piezo actuator 38, a second vibration control layer 40, and a second housing 42; and the first housing is fixed to the glass plate.

Description

Glass diaphragm and glass module

[0001] The present disclosure relates to a glass diaphragm and a glass module.

[0002] In recent years, technology has been studied for vibrating a glass plate to function as a speaker. Japanese Patent Application Laid-Open Nos. 2009-100223 and 2023-7454 disclose glass diaphragms that include a glass plate, a vibrating body, and a fixing member for fixing the vibrating body to the glass plate.

[0003] For example, a piezoelectric actuator (piezoelectric element) can be used as the vibrating body. In this case, when the piezoelectric actuator vibrates, the vibration is transmitted from the fixing member to the glass plate, causing the glass plate to generate various sounds.

[0004] The fixing member affects the acoustic characteristics of the glass plate. Japanese Patent Application Publication No. 2009-100223 and Japanese Patent Application Publication No. 2023-7454 leave room for improvement in terms of the fixing member. Specifically, Japanese Patent Application Publication No. 2009-100223 discloses that a conductor for attaching a vibration actuator to an organic EL panel is attached to the organic EL panel with an adhesive. The vibration actuator is configured by attaching annular piezoelectric elements to both the front and back sides of a metal substrate, and the metal substrate is fixed to the conductors with screws. However, in the configuration of Japanese Patent Application Publication No. 2009-100223, the metal substrate to which the piezoelectric elements are attached is fixed to the conductors with screws, which poses a problem: the screws loosen due to vibration of the piezoelectric elements, making it impossible to achieve the desired acoustic characteristics. Japanese Patent Application Publication No. 2023-7454 discloses a vibration device in which a vibration element is attached to a diaphragm with an adhesive. However, in JP 2023-7454 A, the vibration element is adhered to the diaphragm with an adhesive material such as double-sided adhesive tape. Therefore, JP 2023-7454 A has a problem in that the vibration of the vibration element is absorbed by the adhesive, which deteriorates the frequency response characteristics and phase characteristics, making it impossible to exhibit the desired acoustic characteristics.

[0005] In consideration of the above, the present disclosure aims to provide a glass diaphragm and a glass module that can easily cause the glass plate to exhibit desired acoustic characteristics when a piezoelectric actuator vibrates.

[0006] The glass diaphragm according to the present disclosure is a glass diaphragm having a glass plate and a piezoelectric actuator module fixed to the glass plate, wherein the piezoelectric actuator module has a first housing, a first vibration-damping layer, a piezoelectric actuator, a second vibration-damping layer, and a second housing, and the first housing is fixed to the glass plate.

[0007] The glass module according to the present disclosure is a glass module to which a glass diaphragm is attached, and is equipped with a control device that causes the piezoelectric actuator to function as an active noise canceling device that attenuates noise in any frequency band between 100 Hz and 40,000 Hz, inclusive, or as an acoustic device that generates sound in any frequency band between 100 Hz and 40,000 Hz, inclusive.

[0008] The glass diaphragm and glass module according to the present disclosure make it easy to cause the glass plate to exhibit desired acoustic characteristics when the piezoelectric actuator vibrates.

[0009] 1 is a perspective view of a glass diaphragm according to an embodiment of the present disclosure; FIG. 2 is a cross-sectional view of a piezoelectric actuator module according to an embodiment in a separated state; FIG. 3 is an exploded perspective view of a piezoelectric actuator module according to an embodiment; FIG. 4 is a schematic cross-sectional view taken along the arrow 4-4 of FIG. 3; FIG. 5 is a cross-sectional view of a piezoelectric actuator module according to an embodiment in an assembled state; FIG. 6 is a schematic view of a glass module including a glass diaphragm; FIG. 7 is a schematic side view of a glass diaphragm and an FFT analyzer according to an example; FIG. 8 is a schematic side view of a glass diaphragm and an FFT analyzer according to comparative example 1; FIG. 9 is a schematic side view of a glass diaphragm and an FFT analyzer according to comparative example 2; FIG. 10 is a table showing the constituent materials and vibration performance of an example and comparative examples 1 to 3; FIG. 11 is a Bode plot showing the relationship between the frequency and phase of vibration of a piezoelectric actuator module according to an example; FIG. 12 is a Bode plot showing the relationship between the frequency and phase of vibration of a piezoelectric actuator module according to comparative example 1; FIG. 13 is a Bode plot showing the relationship between the frequency and phase of vibration of a piezoelectric actuator module according to comparative example 2; FIG. 14 is a side view of a piezo actuator module and a glass plate according to a first modified example. FIG. 10 is a side view of a piezoelectric actuator module and a glass plate according to a second modified example.

[0010] A glass diaphragm and a glass module according to an embodiment will be described with reference to the drawings. In each drawing, an arrow FR indicates the front, an arrow UP indicates the upper side, and an arrow LH indicates the left side.

[0011] As shown in FIGS. 1 to 5, the glass diaphragm 10 of this embodiment includes a glass plate 11, an adhesive layer 14, and a piezoelectric actuator module 20.

[0012] (Glass Plate 11) The glass plate 11 may be composed of a single glass plate (single-pane glass), or may be composed of laminated glass in order to improve the acoustic effect of the glass plate 11. For example, the glass plate 11 may be composed of laminated glass in which a first glass plate, an intermediate layer, and a second glass plate are laminated together. The glass plate 11 may also be window glass installed in a vehicle, airplane, train, ship, or helicopter. For example, the glass plate 11 is used for vehicle windshields, side windows, rear windows, rear quarter windows, front bench glass, roof glass, and wind reflectors, but can also be used for applications other than vehicles, such as architectural window glass. For example, when the glass plate 11 is used as window glass for a vehicle, the vehicle has an interior space surrounded by the glass plate 11.

[0013] The glass plate 11 may be formed of transparent or translucent inorganic glass or organic glass. Examples of inorganic glass include soda-lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, and quartz glass. Examples of organic glass include PMMA (polymethyl methacrylate)-based resin, PC (polycarbonate)-based resin, PS (polystyrene)-based resin, PET (polyethylene terephthalate)-based resin, PVC (polyvinyl chloride)-based resin, and cellulose-based resin. Furthermore, when the glass plate 11 is formed of laminated glass, the glass plate on the piezo actuator module 20 side may be formed of a plate-like body made of a material other than glass. For example, a resin plate made of a transparent resin material such as an acrylic plate may be used, or a fiber-reinforced plastic containing glass fiber or carbon fiber may be used.

[0014] The thickness of the glass plate 11 is preferably 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. This allows the glass plate 11 to have sufficient strength. When the glass plate 11 is constructed as laminated glass, the thickness of each glass plate is preferably 5.0 mm or less, more preferably 3.0 mm or less, and even more preferably 2.0 mm or less. Furthermore, the thickness of each glass plate is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 1.0 mm or more.

[0015] The interlayer of laminated glass is formed from a resin film containing a thermoplastic or thermosetting adhesive material, such as a transparent polyvinyl butyral (PVB)-based or ethylene-vinyl acetate copolymer (EVA)-based resin film, silicone (PDMS), polyurethane, fluorine-based, polyethylene terephthalate, or polycarbonate. The interlayer is not limited to a resin film; it may also be composed of a fluid layer containing a liquid or a gel-like substance, which can achieve a high loss factor. The term "fluid" encompasses all fluid materials, including liquids, semisolids, mixtures of solid powder and liquid, and solid gels (jelly-like substances) impregnated with liquid. Furthermore, the interlayer may contain materials that enhance sound insulation, absorb ultraviolet or infrared rays, or be a multi-layer interlayer with a functional layer. The thickness of the intermediate layer may be set to, for example, 1.0 nm or more and 1.0 mm or less, 0.1 μm or more and 0.9 mm or less, or 0.2 μm or more and 0.8 mm or less. The intermediate layer may be a light control film.

[0016] Note that when the glass plate 11 is constructed as laminated glass, it is not limited to laminated glass in which one interlayer is sandwiched between two glass plates. For example, two or more interlayers may be sandwiched between two glass plates, and a light-control film that electrically changes the visible light transmittance may be sandwiched between the two or more interlayers. Examples of light-control films that can be used include twisted nematic (TN) liquid crystal films, vertical alignment (VA) liquid crystal films, polymer dispersed liquid crystal (PDLC) films, suspended particle device (SPD) films, polymer network liquid crystal (PNLC) films, guest-host liquid crystal films, electrochromic materials, and photochromic materials. Furthermore, the glass plate 11 may be constructed of three or more glass plates, each sandwiching an interlayer between adjacent glass plates.

[0017] The glass sheet 11 may have a curved shape such that the vehicle exterior side is convex when installed in a vehicle. When the glass sheet 11 is a laminated glass, both the first glass sheet and the second glass sheet may have a curved shape such that the vehicle exterior side is convex. The glass sheet 11 may have a single-curve shape curved in only one direction, either the left-right direction or the up-down direction, or a compound-curve shape curved in both the left-right direction and the up-down direction. The radius of curvature of the glass sheet 11 may be 2000 to 11000 mm. The radius of curvature of the glass sheet 11 in the left-right direction and the up-down direction may be the same or different. Gravity forming, press forming, roller forming, or the like is used to bend the glass sheet 11.

[0018] The glass plate 11 may have, on at least a portion of its surface, a coating having functions such as water repellency, low reflectivity, low emissivity, ultraviolet shielding, infrared shielding, and coloring. When the glass plate 11 is laminated glass, at least a portion of the interior of the laminated glass may have a film having functions such as low reflectivity, low emissivity, ultraviolet shielding, infrared shielding, and coloring. Furthermore, at least a portion of the interlayer film of the laminated glass may have functions such as ultraviolet shielding, infrared shielding, and coloring.

[0019] (Piezoelectric Actuator Module) The glass plate 11 has one main surface 12A and the other main surface 12B, and the piezoelectric actuator module 20 is fixed to the one main surface 12A via an adhesive layer 14. The adhesive layer 14 may be made of an adhesive, a pressure-sensitive adhesive, or the like. The pressure-sensitive adhesive may be a sheet-shaped adhesive tape. Alternatively, the adhesive may be a sheet-shaped thermosetting resin material or the like.

[0020] The thinner the adhesive layer 14, the more effectively it transmits vibrations from the piezoelectric actuator module 20 to the glass plate 11. Therefore, a thickness of 5.0 mm or less is sufficient, preferably 3.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less. On the other hand, if the adhesive layer 14 is too thin, the adhesive layer 14 may not exhibit the required adhesive strength, or the adhesive process may be difficult, resulting in poor adhesion. Therefore, a thickness of at least 0.001 mm or more is preferable, preferably 0.005 mm or more, and even more preferably 0.01 mm or more is preferable. Although the adhesive layer 14 of this embodiment is formed to a constant thickness, the thickness may vary.

[0021] As shown in FIGS. 2 to 5, the piezoelectric actuator module 20 includes a first housing 22, a terminal 31, a first vibration-damping layer 35, a piezoelectric actuator 38, a second vibration-damping layer 40, and a second housing 42.

[0022] The first housing 22, made of metal, resin, or ceramic, is a plate-like member having a rectangular front shape. A fixing surface 23, which is one surface of the first housing 22 in the thickness direction, is fixed to the main surface 12A via an adhesive layer 14. A recess 25 is formed in an abutment surface 24, which is one surface of the first housing 22 in the thickness direction. As shown in FIGS. 3 and 4 , a pair of connection holes 27 are formed in the first housing 22. Each connection hole 27 has a first portion 28 extending from one side surface (bottom surface) 26 of the first housing 22 along the longitudinal direction of the first housing 22 and a second portion 29 extending from the tip of the first portion 28 to the bottom surface of the recess 25. Furthermore, as shown in FIG. 3 , a plurality of female threaded holes 30 are formed in the abutment surface 24.

[0023] 3 and 4, a terminal 31 having an L-shaped cross section is inserted into each connection hole 27. The terminal 31 has a first component portion 32 parallel to the first portion 28 and a second component portion 33 parallel to the second portion 29. The tip of the first component portion 32 is located in the middle of the first portion 28, and the tip of the second component portion 33 protrudes into the recess 25 from the bottom surface of the recess 25.

[0024] The first damping layer 35 is a plate-like member having a rectangular front shape. The resin first damping layer 35 can be made of, for example, rubber, film, foam, grease, sol, gel, oil, or liquid, and can have adhesive properties. For example, silicone grease or double-sided tape can be used as the first damping layer 35. The front shape of the first damping layer 35 is substantially the same as that of the recess 25, and the thickness of the first damping layer 35 is smaller than that of the recess 25. A pair of through holes 36 are formed in the first damping layer 35. The first damping layer 35 is housed in the recess 25 in contact with the bottom surface of the recess 25. Furthermore, the second components 33 of the terminal 31 are inserted into each through hole 36. The tip end surface (front end surface) of each second component 33 is continuous with the front surface of the first damping layer 35.

[0025] The piezoelectric actuator 38 is a plate-like member having a rectangular front shape. The front shape of the piezoelectric actuator 38 is substantially the same as that of the recess 25, and the thickness of the piezoelectric actuator 38 is smaller than that of the recess 25. A pair of metal terminals 39 (see FIG. 3) is provided on the surface of the piezoelectric actuator 38 facing the first vibration damping layer 35. The piezoelectric actuator 38 is housed in the recess 25 in a state of contact with the front surface of the first vibration damping layer 35. Furthermore, the front end surface of the second component portion 33 of the corresponding terminal 31 contacts each terminal 39.

[0026] The second vibration-damping layer 40 made of resin is a plate-like member having the same specifications as the first vibration-damping layer 35. The second vibration-damping layer 40 is housed in the recess 25 in a state of contact with the front surface of the piezo actuator 38. The front surface of the second vibration-damping layer 40 is located substantially flush with the abutment surface 24 of the first housing 22.

[0027] The second housing 42, made of metal, resin, or ceramic, is a plate-like member having a rectangular front shape. The second housing 42 has the same number of through holes 43 as the number of female screw holes 30. As shown in FIG. 5 , the first housing 22, the first vibration-damping layer 35, the piezoelectric actuator 38, the second vibration-damping layer 40, and the second housing 42 are stacked in this order from the glass plate 11 side. The rear surface of the second housing 42 is in contact with the abutment surface 24 of the first housing 22 and the front surface of the second vibration-damping layer 40, and the female screw holes 30 and the through holes 43 face each other. Note that, for example, a spring, rubber, a washer, an O-ring, a film, foam, gel, grease, or the like may be interposed between the bottom surface of the recess 25 of the first housing 22 and the first vibration-damping layer 35, or between the rear surface of the second housing 42 and the second vibration-damping layer 40.

[0028] A screw 45 is inserted into each through hole 43 of the second housing 42, and each screw 45 is threaded into the corresponding female threaded hole 30. As a result, as shown in Fig. 5, the rear surface of the second housing 42 comes into contact with the abutment surface 24 of the first housing 22, and the first damping layer 35, the piezo actuator 38, and the second damping layer 40 are sandwiched between the bottom surface of the recess 25 and the rear surface of the second housing 42. Furthermore, the front shapes of the first damping layer 35, the piezo actuator 38, and the second damping layer 40 are substantially the same as the front shape of the recess 25. Therefore, movement of the first damping layer 35, the piezo actuator 38, and the second damping layer 40 within the recess 25 is substantially restricted.

[0029] Furthermore, one end of each of the two cables 47 shown in FIGS. 1, 3 and 4 is inserted into the first portion 28 of each connection hole 27 and connected to the corresponding terminal 31 .

[0030] The Young's modulus of at least one of the first housing 22 and the second housing 42 is 10 ８ Pa or more and 10 １２ Regardless of the Young's modulus of the first housing 22 and the second housing 42, it is preferable that the first housing 22 and the second housing 42 have higher rigidity than the first damping layer 35 and the second damping layer 40.

[0031] The Young's modulus of at least one of the first and second damping layers 35 and 40 is 10 ２ Pa or more 10 ７ It is preferable that the viscosity is 0.05 Pa or less.

[0032] At least one of the first damping layer 35 and the second damping layer 40 has a thickness of 0.001 mm or more and 3 mm or less.

[0033] When the first vibration-damping layer 35 and the second vibration-damping layer 40 have adhesive properties such as silicone grease or double-sided tape, it is preferable that at least one of the adhesive strength between the first vibration-damping layer 35 and the piezoelectric actuator 38 and the adhesive strength between the piezoelectric actuator 38 and the second vibration-damping layer 40 be 1 MPa or less.

[0034] The front shapes of the first housing 22 and the second housing 42 may be shapes other than rectangular. The front shapes of the recess 25, the first vibration-damping layer 35, the piezo actuator 38, and the second vibration-damping layer 40 may also be shapes other than rectangular.

[0035] The fastening means for mechanically fastening the first housing 22 and the second housing 42 may be something other than the female threaded hole 30 and the screw 45. However, the fastening means applied to the piezoelectric actuator module 20 is preferably a means that allows an operator to easily remove the second housing 42 from the first housing 22. For example, the fastening means may be an elastically deformable locking claw provided on one of the first housing 22 and the second housing 42 and an engaging portion that is engageable with the locking claw provided on the other of the first housing 22 and the second housing 42. The fastening means may also be a slide mechanism that slides the first housing 22 and the second housing 42 relative to each other to attach and detach the first housing 22 and the second housing 42 from each other. The fastening means may also be a plunger provided on one of the first housing 22 and the second housing 42 and a locking hole that allows the plunger to be inserted and removed from the other of the first housing 22 and the second housing 42. The fixing means may also be a leaf spring or the like.

[0036] Furthermore, the joining means for fixing the main surface 12A and the piezoelectric actuator module 20 may be different from the adhesive layer 14. For example, the joining means may be a means for mechanically fastening the main surface 12A and the first housing 22. Examples of such a means include a female threaded hole formed in the main surface 12A, a protruding piece provided on the first housing 22 and having a through hole, and a screw that is inserted into the through hole with the protruding piece in contact with the main surface 12A and that is screwed into the female threaded hole.

[0037] As shown in FIG. 6 , the piezoelectric actuator 38 is connected to a power supply (not shown) via cables 47 and the control device 15. In this specification, a configuration including the glass diaphragm 10, the control device 15, and the cable 47 is referred to as a glass module 13. The piezoelectric actuator 38 vibrates in response to an electrical signal input to the piezoelectric actuator 38 from the control device 15 via the cable 47. The vibration direction of the piezoelectric actuator 38 is the thickness direction of the piezoelectric actuator 38 (glass plate 11). The vibration generated by the piezoelectric actuator 38 is transmitted to the glass plate 11 via the first vibration damping layer 35, the second vibration damping layer 40, the first housing 22, and the second housing 42, causing the glass plate 11 to vibrate.

[0038] When the glass sheet 11 is a vehicle window glass, the control device 15 is, for example, an ECU (Electronic Control Unit) having a CPU, ROM, RAM, storage, a communication I / F, and an input / output I / F. For example, the control device 15 can vibrate the piezo actuator 38 to attenuate noise in any frequency band between 100 Hz and 40,000 Hz. That is, the control device 15 can cause the piezo actuator 38 to function as an active noise canceling device. The control device 15 can also cause the piezo actuator 38 to function as an acoustic device that generates sound in any frequency band between 100 Hz and 40,000 Hz.

[0039] In the piezo actuator module 20 of this embodiment described above, the piezo actuator 38 is sandwiched between the first vibration-damping layer 35 and the second vibration-damping layer 40. Furthermore, a material having a certain degree of hardness and harder than the first vibration-damping layer 35 and the second vibration-damping layer 40 (for example, a material having a Young's modulus of 10 ８ Pa or more and 10 １２The first and second vibration-damping layers 35 and 40 are sandwiched between the first and second housings 22 and 42, each made of a hardness of 100 Hz or less. Therefore, the first and second housings 22 and 42, which are harder than the first and second vibration-damping layers 35 and 40, suppress vibration disturbances of the piezo actuator 38, while the first and second vibration-damping layers 35 and 40, which are softer than the first and second housings 22 and 42 and have a damping function, suppress resonance of the piezo actuator module 20 itself. Therefore, the piezo actuator module 20 of this embodiment is unlikely to experience a phase shift of ±180° or more when vibrating at a frequency of 100 Hz or higher. Therefore, the glass diaphragm 10 of this embodiment easily allows the glass plate 11 to exhibit desired acoustic characteristics when the piezo actuator 38 vibrates.

[0040] By setting the adhesive strength between the first vibration-damping layer 35 and the piezoelectric actuator 38, and the adhesive strength between the piezoelectric actuator 38 and the second vibration-damping layer 40 to 1 MPa or less, the piezoelectric actuator 38 can be easily separated from the first vibration-damping layer 35 and the second vibration-damping layer 40. Therefore, for example, if the piezoelectric actuator 38 breaks down, the screws 45 can be removed from the female threaded holes 30 and the second housing 42 can be separated from the first housing 22 and the second housing 42, after which the piezoelectric actuator 38 can be easily separated from the first housing 22 and the second housing 42. Therefore, it is easy to replace the piezo actuator 38 with a new piezo actuator 38.

[0041] Furthermore, the piezoelectric actuator 38 is covered by the hard first housing 22 and second housing 42. Therefore, when an external impact occurs, i.e., when some object collides with the piezoelectric actuator module 20, the piezoelectric actuator 38 is less likely to be damaged.

[0042] Next, Examples 1 to 5 and Comparative Examples 1 to 3 to which the present disclosure is applied will be described with reference to FIGS.

[0043] Example 1 The specifications of the adhesive layer 14, first housing 22, first vibration-damping layer 35, second vibration-damping layer 40, and second housing 42 of Example 1 are as shown in FIG. 10 . As shown in FIG. 7 , the piezo actuator module 20 of Example 1 is fixed to the center of the main surface 12A of a glass plate 11 via the adhesive layer 14. The adhesive layer 14 is a 0.25 mm thick adhesive tape (3M, 9473PC). The front shape of the glass plate 11 is square, and the lengths of the four sides of the glass plate 11 are 600 mm. The thickness of the glass plate 11 is 3.2 mm. The main surface 12B of the glass plate 11 is fixed to a metal frame 16 via an adhesive 17. The adhesive 17 is "Sika-TackGO" manufactured by Sika Corporation. An acceleration sensor 18 is fixed to the center of the main surface 12B. A sweep signal of 100 to 2000 Hz was output from the FFT analyzer 19 (DS3200 manufactured by Ono Sokki Co., Ltd.) to the piezo actuator 38 via the cable 47, and the output result of the acceleration sensor 18 was used to measure the vibration phase of the piezo actuator module 20.

[0044] FIG. 11 is a Bode plot showing the results of measuring the vibration phase of the piezoelectric actuator module 20 of Example 1. As is clear from this Bode plot, the absolute value of the phase difference at frequencies of 100 Hz or higher for the piezoelectric actuator module 20 of Example 1 is less than 180°. Therefore, it is easy to correct the vibration phase of the piezoelectric actuator module 20 (piezo actuator 38) to a desired value by signal processing. As a result, the phase characteristics of the piezoelectric actuator module 20 (glass diaphragm 10) of Example 1 are excellent (see FIG. 10). Therefore, the glass diaphragm 10 equipped with the piezoelectric actuator module 20 of Example 1 easily causes the glass plate 11 to exhibit desired acoustic characteristics when the piezo actuator 38 vibrates.

[0045] Furthermore, in the piezoelectric actuator module 20 of Example 1, at least one of the adhesive strength between the first vibration-damping layer 35 and the piezoelectric actuator 38 and the adhesive strength between the piezoelectric actuator 38 and the second vibration-damping layer 40 is 1 MPa or less. Therefore, the piezoelectric actuator 38 can be easily replaced (see FIG. 10).

[0046] Furthermore, the piezoelectric actuator module 20 of Example 1 has the first housing 22 and the second housing 42 which are hard and cover the entire piezoelectric actuator 38. Therefore, the physical strength of the piezoelectric actuator module 20 of Example 1 is good (see FIG. 10).

[0047] As described above, the piezoelectric actuator module 20 of Example 1 has good phase characteristics, good interchangeability of the piezoelectric actuator 38, and good physical strength, and therefore the overall evaluation of the piezoelectric actuator module 20 of Example 1 is good (see FIG. 10).

[0048] Comparative Examples 1 to 3: Fig. 8A shows an embodiment of Comparative Example 1, and Fig. 8B shows an embodiment of Comparative Example 2. As shown in Figs. 8A and 8B, in Comparative Examples 1 and 2, a piezo actuator 38 is fixed to the center of the main surface 12A of a glass plate 11 via an adhesive layer 14. As shown in Fig. 9, in Comparative Example 3, a piezo actuator 38 is fixed to a metal body 50 made of SUS304 via an adhesive layer 14, and the metal body 50 is fixed to the center of the main surface 12A of the glass plate 11 via an adhesive layer 14. The specifications of the glass plate 11 in Comparative Examples 1 to 3 are the same as those of the glass plate 11 in Fig. 7. In Comparative Examples 1 to 3, an acceleration sensor 18 is fixed to the center of the main surface 12B, and a sweep signal of 100 to 2000 Hz is output from an FFT analyzer 19 via a cable 47 to the piezo actuator 38. The output of the acceleration sensor 18 is used to measure the vibration phase of the piezo actuator 38. The specifications of the acceleration sensor 18 and FFT analyzer 19 in Comparative Examples 1 to 3 are the same as those in Example 1. The specifications of the adhesive layer 14 in Comparative Examples 1 to 3 are as shown in FIG. 10 . In Comparative Example 1, the adhesive layer 14 is a 0.25 mm thick adhesive tape (3M, 9473PC), and in Comparative Example 2, the adhesive layer 14 is a 3.0 mm thick adhesive tape (3M, 7130). In Comparative Example 3, both adhesive layers 14, 14 are 0.25 mm thick adhesive tape (3M, 9473PC), and the metal body 50 has a thickness of 1.0 mm.

[0049] FIG. 12 is a Bode plot showing the results of vibration phase measurement of the piezo actuator 38 of Comparative Example 1. As is clear from this Bode plot, the absolute value of the phase difference of the piezo actuator 38 of Comparative Example 1 is greater than 180° at frequencies of 100 Hz or higher. FIG. 13 is a Bode plot showing the results of vibration phase measurement of the piezo actuator 38 of Comparative Example 2. As is clear from this Bode plot, the absolute value of the phase of the piezo actuator 38 of Comparative Example 2 is greater than 180° at frequencies of 100 Hz or higher. Although a Bode plot is omitted, the absolute value of the phase of the piezo actuator 38 of Comparative Example 3 is also greater than 180° at frequencies of 100 Hz or higher. Therefore, it is difficult to correct the vibration phase of the piezo actuator 38 to a desired value by signal processing. Therefore, the phase characteristics of the piezo actuators 38 (glass diaphragms 10) of Comparative Examples 1 to 3 are poor (see FIG. 10 ). Therefore, the glass diaphragm 10 equipped with the piezoelectric actuator modules 20 of Comparative Examples 1 to 3 makes it difficult for the glass plate 11 to exhibit the desired acoustic characteristics when the piezoelectric actuators 38 vibrate.

[0050] Furthermore, the piezo actuators 38 of Comparative Examples 1 and 2 are fixed to the glass plate 11 via an adhesive layer 14. Furthermore, the piezo actuator 38 of Comparative Example 3 is fixed to the metal body 50 via an adhesive layer 14, and the metal body 50 is fixed to the glass plate 11 via the adhesive layer 14. Therefore, when a malfunction occurs in the piezo actuators 38 of Comparative Examples 1 to 3, it is not easy to remove these piezo actuators 38 from the glass plate 11. Therefore, it is not easy to replace the piezo actuators 38 of Comparative Examples 1 to 3 (see FIG. 10 ).

[0051] Furthermore, the piezo actuators 38 of Comparative Examples 1 to 3 are not covered with members corresponding to the first housing 22 and the second housing 42. Therefore, the physical strength of the piezo actuators 38 of Comparative Examples 1 to 3 is poor (see FIG. 10).

[0052] As described above, the piezoelectric actuators 38 (glass diaphragms 10) of Comparative Examples 1 to 3 have poor phase characteristics, are not able to be replaced non-destructively in the event of a malfunction, and have poor physical strength, so the overall evaluation of the piezoelectric actuators 38 of Comparative Examples 1 to 3 is not good (see FIG. 10).

[0053] <Examples 2 and 3> The specifications of the adhesive layer 14, first housing 22, first damping layer 35, second damping layer 40, and second housing 42 in Examples 2 and 3 are as shown in FIG. 10 . The method of fixing the piezoelectric actuator module 20 to the glass plate 11, as well as the specifications of the glass plate 11, adhesive 17, acceleration sensor 18, and FFT analyzer 19 in Examples 2 and 3, are the same as in Example 1. Although Bode plots are not shown, the absolute values ​​of the phase differences of the piezoelectric actuator modules 20 in Examples 2 and 3 at frequencies of 100 Hz or higher are less than 180°. Therefore, the glass diaphragm 10 equipped with the piezoelectric actuator modules 20 in Examples 2 and 3 easily exerts desired acoustic characteristics on the glass plate 11 when the piezoelectric actuator 38 vibrates. Furthermore, the piezoelectric actuator modules 20 (glass diaphragms 10) of Examples 2 and 3, like Example 1, have good replaceability of the piezoelectric actuators 38 and good physical strength of the piezoelectric actuator modules 20 (see FIG. 10). Therefore, the overall evaluation of the piezoelectric actuator modules 20 of Examples 2 and 3 is good (see FIG. 10).

[0054] <Examples 4 and 5> The specifications of the adhesive layer 14, first housing 22, first vibration-damping layer 35, second vibration-damping layer 40, and second housing 42 of the piezoelectric actuator module of Example 4 are as shown in Fig. 10. As is clear from Fig. 10, the piezoelectric actuator module of Example 5 includes the adhesive layer 14, first housing 22, and second housing 42, but does not include the first vibration-damping layer 35 and the second vibration-damping layer 40. The method of fixing the piezoelectric actuator modules of Examples 4 and 5 to the glass plate 11, and the specifications of the glass plate 11, adhesive 17, acceleration sensor 18, and FFT analyzer 19 are the same as those of Example 1.

[0055] Like Example 1, the piezo actuator modules (glass diaphragm 10) of Examples 4 and 5 have good replaceability of the piezo actuator 38 and good physical strength of the piezo actuator module (see FIG. 10 ). Although a Bode plot is not shown, the phase characteristics of the piezo actuator module of Example 4 are inferior to those of Examples 1 to 3. However, the absolute value of the phase of the piezo actuator module of Example 4 is less than 180° at frequencies of 100 Hz or higher. Therefore, the glass diaphragm 10 equipped with the piezo actuator module 20 of Example 4 is likely to exhibit the desired acoustic characteristics in the glass plate 11 when the piezo actuator 38 vibrates. Therefore, the overall evaluation of the piezo actuator module of Example 4 is good (see FIG. 10 ). On the other hand, although a Bode plot is not shown, the absolute value of the phase of the piezo actuator module of Example 5 is greater than 180° at frequencies of 100 Hz or higher. In other words, the phase characteristics of the piezo actuator module of Example 5 are poor (see FIG. 10 ). Therefore, the overall evaluation of the piezoelectric actuator module of Example 5 is not good (see FIG. 10).

[0056] The above-described embodiments and the configurations of Examples 1 to 3 show examples of the contents of the present disclosure, and may be combined with other known technologies, or some of the configurations may be omitted or modified within the scope of the gist of the present disclosure.

[0057] For example, the present disclosure may be implemented in the form of a first modified example shown in Fig. 14. In the first modified example, the main surface 12A of the glass plate 11A is configured as a curved surface. Furthermore, the fixing surface 23 of the first housing 22 of the piezoelectric actuator module 20A in the first modified example is configured as a curved surface having a shape corresponding to the curved surface of the main surface 12A. According to the first modified example, the fixing surface 23 can be firmly fixed to the curved main surface 12A by using an adhesive layer 14 (not shown in Fig. 14).

[0058] The present disclosure may also be implemented in the form of a second modified example shown in FIG. 15 . In the second modified example, the outer peripheral surface 22A1 of the first housing 22A of the piezoelectric actuator module 20B is configured as a portion of a spherical surface. Furthermore, the outer peripheral surface 42A1 of the second housing 42A is configured as a portion of the spherical surface. Therefore, when the second housing 42A is fixed to the first housing 22A, the outer peripheral surfaces 22A1 and 42A1 are continuous, as shown in FIG. 15 , and the outer peripheral surfaces 22A1 and 42A1 form a portion of a spherical surface. For example, when the glass plate 11 is used as a vehicle windshield and the main surface 12A is exposed to the outside of the vehicle, liquid (e.g., rain) may flow from the top to the bottom of the main surface 12A of the glass plate 11 along the arrow DR. In this case, the liquid is more likely to flow downward over the surface of the piezoelectric actuator module 20B. In other words, in this case, the risk of liquid accumulating in the upper part of the piezoelectric actuator module 20B is reduced.

[0059] In addition to the piezoelectric actuator modules 20, 20A, and 20B, voice coil type actuators may be attached to the glass plates 11 and 11A.

[0060] The recesses 25 may be formed in the second housings 42, 42A instead of the first housings 22, 22A. Alternatively, the recesses 25 may be formed in the first housings 22, 22A and the second housings 42, 42A. Alternatively, the recesses 25 may not be formed in the first housings 22, 22A and the second housings 42, 42A.

[0061] The first and second damping layers 35 and 40 may have different specifications. For example, the first and second damping layers 35 and 40 may be made of different materials.

[0062] The materials constituting the first housing 22, 22A and the second housing 42, 42A may be different from each other.

[0063] The piezoelectric actuator modules of the embodiment and each modified example do not necessarily have to include a second vibration-damping layer. In this case, the front surface of the piezo actuator 38 may contact the rear surface of the second housing 42, or a spring, rubber, washer, O-ring, film, foam, gel, grease, or the like may be interposed between the rear surface of the second housing 42 and the front surface of the piezo actuator 38. Although a Bode diagram is not shown, if the specifications of the first housing 22, first vibration-damping layer 35, piezo actuator 38, and second housing 42 of the piezoelectric actuator module of this modified example are the same as those of any of Examples 1 to 3, the absolute value of the phase difference of the piezo actuator module of this modified example at frequencies of 100 Hz or higher is less than 180°. Therefore, the glass diaphragm 10 equipped with the piezo actuator module of this modified example easily exerts the desired acoustic characteristics on the glass plates 11 and 11A when the piezo actuator 38 vibrates. Furthermore, the piezo actuator of this modified example has good replaceability and physical strength, so the overall evaluation of the piezo actuator module of this modified example is good.

[0064] As shown in Fig. 14, the main surface 12B opposite to the main surface 12A of the glass plate 11A is also formed as a curved surface. The fixing surface 23 of the first housing 22 of the piezoelectric actuator module 20B, shown by imaginary lines in Fig. 14, is formed as a curved surface having a shape corresponding to the curved surface of the main surface 12B. This fixing surface 23 may be fixed to the main surface 12B using an adhesive layer 14 (not shown in Fig. 14).

[0065] The disclosure of Japanese Patent Application No. 2023-146518, filed on September 8, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0066] REFERENCE SIGNS LIST 10 Glass vibration plate 11 11A Glass plate 13 Glass module 14 Adhesive layer 20 20A 20B Piezoelectric actuator module 22 22A First housing 25 Recess 31 Terminal 35 First vibration damping layer 38 Piezoelectric actuator 40 Second vibration damping layer 42 42A Second housing

Claims

1. A glass diaphragm having a glass plate and a piezoelectric actuator module fixed to the glass plate, the piezoelectric actuator module having a first housing, a first vibration-damping layer, a piezoelectric actuator, a second vibration-damping layer, and a second housing, the first housing being fixed to the glass plate.

2. The glass diaphragm according to claim 1, wherein the first housing, the first vibration-damping layer, the piezoelectric actuator, the second vibration-damping layer and the second housing are laminated in this order from the glass plate side.

3. The glass diaphragm according to claim 1 or 2, wherein the rigidity of the first housing and the second housing is higher than the rigidity of the first vibration-damping layer, the piezoelectric actuator and the second vibration-damping layer.

4. The Young's modulus of at least one of the first housing and the second housing is 10 ８ Pa or more and 10 １２ The glass diaphragm according to claim 1 or 2, wherein the modulus of elasticity is 0.01 Pa or less.

5. The Young's modulus of at least one of the first vibration-damping layer and the second vibration-damping layer is 10 ２ Pa or more 10 ７ The glass diaphragm according to claim 1 or 2, wherein the modulus of elasticity is 0.01 Pa or less.

6. The glass diaphragm according to claim 1 or 2, wherein the thickness of at least one of the first and second vibration-damping layers is 0.001 mm or more and 3 mm or less.

7. The glass diaphragm according to claim 1 or 2, wherein the first housing and the second housing are mechanically fastened to each other.

8. A glass diaphragm according to claim 1 or 2, wherein at least one of the adhesive strength between the first housing and the first vibration-damping layer and the adhesive strength between the second housing and the second vibration-damping layer is 1 MPa or less.

9. The glass diaphragm according to claim 1 or 2, wherein the first housing is fixed to the glass plate via an adhesive layer.

10. The glass diaphragm according to claim 1 or 2, wherein the first housing and the glass plate are mechanically fastened together.

11. A glass diaphragm as described in claim 1 or 2, wherein at least one of the first housing and the second housing has a recess, and the first vibration-damping layer, the piezoelectric actuator and the second vibration-damping layer are housed in the recess.

12. The glass diaphragm according to claim 1 or 2, wherein the piezoelectric actuator module is provided with a terminal capable of being electrically connected to the piezoelectric actuator.

13. The glass diaphragm according to claim 1 or 2, wherein the glass plate is made of a single piece of glass.

14. The glass diaphragm according to claim 1 or 2, wherein the glass plate is a laminated glass in which at least two sheets of glass are bonded together with an intermediate layer.

15. A glass diaphragm according to claim 1 or 2, wherein the first housing is fixed to a curved surface of the glass plate.

16. The glass diaphragm according to claim 1 or 2, wherein a voice coil type actuator is attached to the glass plate.

17. A glass module to which the glass diaphragm according to claim 1 or 2 is attached, comprising a control device that causes the piezoelectric actuator to function as an active noise canceling device that attenuates noise in any frequency band between 100 Hz and 40,000 Hz, inclusive, or as an acoustic device that generates sound in any frequency band between 100 Hz and 40,000 Hz, inclusive.

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