Piezoelectric loudspeaker and manufacturing method thereof

Abstract

A piezoelectric speaker includes a diaphragm and a piezoelectric layer disposed over the diaphragm. The thickness of the piezoelectric layer may be in the range of 20 microns to 120 microns. A width of the piezoelectric layer may be 50 mm or more, and a length of the piezoelectric layer may be 100 mm or more. The piezoelectric layer may also include a pair of electrodes in electrical contact with the piezoelectric layer and configured to drive the piezoelectric layer. A method of manufacturing a piezoelectric speaker includes attaching a single piezoelectric layer and a pair of electrodes to a diaphragm using an adhesive.

Description

[0001] This application claims priority to U.S. Provisional Application No. 63 / 535,416, filed August 30, 2023, pursuant to 35 USC § 119, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure relates to a piezoelectric loudspeaker and a method for manufacturing the same, and more specifically, to a piezoelectric loudspeaker comprising a piezoelectric layer having a thickness of 20 micrometers to 120 micrometers and a method for manufacturing the same. Background Technology

[0003] Loudspeakers are used to deliver audio to users of electronic devices, which can enhance the user's aesthetic experience when using the devices. It is known that sound (e.g., audio) is produced using piezoelectric elements, which can be less expensive than conventional loudspeakers. Such piezoelectric devices are often referred to as "buzzers" because their sound is very low, a result of poor low-frequency performance, especially compared to the high-frequency performance of such buzzers. Therefore, there is a need to develop a piezoelectric loudspeaker with improved low-frequency performance. Summary of the Invention

[0004] This disclosure provides a piezoelectric loudspeaker and a method for manufacturing the same. The piezoelectric loudspeaker can achieve a high average low-frequency amplitude (e.g., 60 dB or greater or 64 dB or greater). Furthermore, the piezoelectric loudspeaker can exhibit a low difference between the average high-frequency amplitude and the average low-frequency amplitude (e.g., 24 dB or less, 20 dB or less, or 10 dB or less). As shown in the examples herein, the dimensions of the piezoelectric element (e.g., a thickness of 120 µm or less and / or corresponding to a thickness greater than 5000 mm) are significant. 2 Larger or larger areas can unexpectedly improve the low-frequency performance of piezoelectric loudspeakers. Piezoelectric loudspeakers can have a single sintered ceramic (e.g., a strip) as the piezoelectric element. Without being bound by theory, sintered ceramic strips can exhibit improved mechanical strength and / or dimensional stability compared to other methods of forming layers (e.g., physical vapor deposition, sputtering).

[0005] The following describes some example aspects of this disclosure. It should be understood that any feature of each aspect may be used alone or in combination with each other.

[0006] Aspect 1. A piezoelectric loudspeaker, comprising:

[0007] Diaphragm;

[0008] A piezoelectric layer disposed above the diaphragm, the piezoelectric layer having a thickness in the range of 20 micrometers to 120 micrometers, a width of 50 millimeters or more, and a length of 100 millimeters or more; and

[0009] A pair of electrodes that are in electrical contact with the piezoelectric layer and configured to drive the piezoelectric layer.

[0010] Aspect 2. The piezoelectric loudspeaker according to aspect 1, wherein the width of the piezoelectric layer is 50 mm to 200 mm, and the length is greater than or equal to the width.

[0011] Aspect 3. The piezoelectric loudspeaker according to any one of Aspects 1 to 2, wherein the length of the piezoelectric layer is 100 mm to 200 mm.

[0012] Aspect 4. The piezoelectric loudspeaker according to any one of Aspects 1 to 3, wherein the piezoelectric layer comprises lead zirconate titanate or alkali metal niobate.

[0013] Aspect 5. The piezoelectric loudspeaker according to any one of Aspects 1 to 4, wherein the piezoelectric layer is a single piezoelectric layer.

[0014] Aspect 6. The piezoelectric loudspeaker according to any one of Aspects 1 to 5, wherein the piezoelectric layer is a sintered ceramic ribbon.

[0015] Aspect 7. The piezoelectric loudspeaker according to any one of Aspects 1 to 6, wherein the piezoelectric layer is attached to the diaphragm by an adhesive layer.

[0016] Aspect 8. The piezoelectric loudspeaker according to any one of Aspects 1 to 7, wherein when the piezoelectric loudspeaker is driven with a voltage of 10 volts to 20 volts, the piezoelectric loudspeaker exhibits an average low-frequency amplitude of sound averaged at frequencies from 100 Hz to 1000 Hz, the difference between the average low-frequency amplitude of the sound and the average high-frequency amplitude of the sound averaged at frequencies from 1000 Hz to 20000 Hz is within 25 dB.

[0017] Aspect 9. The piezoelectric loudspeaker according to aspect 8, wherein the difference between the average low-frequency amplitude of the sound and the average high-frequency amplitude of the sound is within 20 dB.

[0018] Aspect 10. The piezoelectric loudspeaker according to any one of Aspects 8 to 9, wherein the difference between the average low-frequency amplitude of the sound and the average high-frequency amplitude of the sound is within 10 dB.

[0019] Aspect 11. The piezoelectric loudspeaker according to any one of Aspects 1 to 7, wherein when the piezoelectric loudspeaker is driven with a voltage of 10 to 20 volts, the piezoelectric loudspeaker exhibits an average low-frequency amplitude of sound averaged at frequencies from 100 Hz to 1000 Hz, the average low-frequency amplitude of the sound being 60 dB or greater.

[0020] Aspect 12. The piezoelectric loudspeaker according to aspect 11, wherein the average low-frequency amplitude of the sound is 64 dB or greater.

[0021] Aspect 13. A consumer electronic device, comprising:

[0022] The housing includes a front surface, a rear surface, and side surfaces; and

[0023] Electrical components, at least partially within the housing, including a controller, a memory, a display, and a piezoelectric loudspeaker according to any one of aspects 1 to 12.

[0024] Aspect 14. A method of manufacturing a piezoelectric loudspeaker, comprising:

[0025] The piezoelectric loudspeaker is formed by attaching a single piezoelectric layer and a pair of electrodes to a diaphragm using an adhesive, wherein the thickness of the single piezoelectric layer is in the range of 20 micrometers to 120 micrometers, the width of the single piezoelectric layer is 50 millimeters or more, and the length of the single piezoelectric layer is 100 millimeters or more.

[0026] Aspect 15. The method according to aspect 14 further includes sintering the green strip to form the single piezoelectric layer.

[0027] Aspect 16. The method according to any one of Aspects 14 to 15, wherein the width of the single piezoelectric layer is 50 mm to 200 mm, and the length is greater than or equal to the width.

[0028] Aspect 17. The method according to any one of Aspects 14 to 16, wherein the length of the single piezoelectric layer is 100 mm to 200 mm.

[0029] Aspect 18. The method according to any one of Aspects 14 to 17, wherein the single piezoelectric layer comprises lead zirconate titanate or alkali metal niobate.

[0030] Aspect 19. The method according to any one of Aspects 14 to 18, wherein when the piezoelectric loudspeaker is driven with a voltage of 10 to 20 volts, the piezoelectric loudspeaker exhibits an average low-frequency amplitude of sound averaged at frequencies from 100 Hz to 1000 Hz, the difference between the average low-frequency amplitude of the sound and the average high-frequency amplitude of the sound averaged at frequencies from 1000 Hz to 20000 Hz is within 20 dB.

[0031] Aspect 20. The method according to any one of Aspects 14 to 18, wherein when the piezoelectric loudspeaker is driven with a voltage of 10 to 20 volts, the piezoelectric loudspeaker exhibits an average low-frequency amplitude of sound averaged at frequencies of 100 Hz to 1000 Hz, the average low-frequency amplitude of the sound being 60 dB or greater.

[0032] Aspect 21. The method according to any one of aspects 14 to 20, wherein the piezoelectric loudspeaker is a piezoelectric loudspeaker according to any one of aspects 1 to 13. Attached Figure Description

[0033] The above and other features and advantages of various aspects of this disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0034] Figure 1 This is a schematic cross-sectional view of a piezoelectric loudspeaker according to various aspects of this disclosure;

[0035] Figure 2 It is along the piezoelectric loudspeaker Figure 1 A schematic cross-sectional view taken from line 2-2;

[0036] Figure 3 It is a schematic plan view based on various examples of consumer electronic devices;

[0037] Figure 4 yes Figure 3 A schematic perspective view of an example consumer electronic device;

[0038] Figure 5 Experimental results of Examples 1-2 according to various aspects of this disclosure are schematically shown; and

[0039] Figure 6 Simulation results of Examples 3-5 according to various aspects of this disclosure are shown schematically. Detailed Implementation

[0040] like Figure 1-2 As shown, the piezoelectric loudspeaker 101 includes a piezoelectric device 102 having a piezoelectric layer 103 attached to a diaphragm 153. Figure 1 As shown, the piezoelectric device 102 may have a pair of electrodes 123 and 133 that are in electrical contact with the piezoelectric layer 103 and configured to drive the piezoelectric layer 103. Furthermore, as... Figure 1As shown, the piezoelectric layer 103 can be attached to the diaphragm 153 via the adhesive layer 143. Unless otherwise indicated, descriptions of features of various aspects of a piezoelectric loudspeaker are equally applicable to corresponding features of any aspect of this disclosure. For example, the same part numbers throughout this disclosure may indicate that features identified in some aspects are identical to each other, and unless otherwise indicated, descriptions of features identified in one aspect are equally applicable to features identified in any other aspect of this disclosure.

[0041] like Figure 1 As shown, the piezoelectric layer 103 of the piezoelectric device 102 includes a first main surface 105 and a second main surface 107 opposite to the first main surface 105, wherein the thickness 109 is defined as the average distance between the two surfaces. In various aspects, the thickness 109 may be about 10 micrometers (µm) or greater, about 15 µm or greater, about 20 µm or greater, about 25 µm or greater, about 30 µm or greater, about 35 µm or greater, about 40 µm or greater, about 200 µm or less, about 160 µm or less, about 120 µm or less, about 100 µm or less, about 80 µm or less, about 60 µm or less, about 50 µm or less, or about 40 µm or less. In various aspects, the thickness 109 can be in the range of about 10 µm to about 200 µm, about 10 µm to about 160 µm, about 15 µm to about 120 µm, about 15 µm to about 100 µm, about 20 µm to about 80 µm, about 20 µm to about 60 µm, about 20 µm to about 50 µm, about 25 µm to about 50 µm, about 30 µm to about 50 µm, or any range or subrange thereof. In other aspects, a preferred range of the thickness 109 can be about 10 µm to about 200 µm, about 20 µm to about 50 µm, or about 30 µm to about 50 µm. The thickness 109 of the piezoelectric layer 103 can be determined based on scanning electron microscopy (SEM) images of the cross-section of the piezoelectric layer 103, for example by... Figure 1 The view shown is used to determine this.

[0042] like Figure 2 As shown, the piezoelectric layer 103 of the piezoelectric device 102 includes a length L and a width W measured in directions orthogonal to each other and orthogonal to the thickness 109. As used herein, "length" refers to the maximum dimension of the piezoelectric layer measured in a direction perpendicular to the thickness, while "width" refers to the maximum value of the dimension perpendicular to both the thickness and the length. Therefore, the length L is greater than or equal to the width W. Although Figure 1A quadrilateral (e.g., rectangular) piezoelectric layer is depicted, but it should be understood that in other respects, the piezoelectric layer may have any shape (e.g., curved, curved, or other polygonal). In all respects, the length L may be about 100 mm or greater, about 120 mm or greater, about 140 mm or greater, about 150 mm or greater, about 160 mm or greater, about 170 mm or greater, about 180 mm or greater, about 190 mm or greater, about 200 mm or greater, about 500 mm or less, about 200 mm or less, about 180 mm or less, about 160 mm or less, about 150 mm or less, or about 140 mm or less. In all respects, the length L may be in the range of 100 mm to 500 mm, about 100 mm to about 200 mm, about 120 mm to about 180 mm, about 140 mm to about 170 mm or greater, about 150 mm to about 160 mm, or any range or subrange thereof. In all respects, the width W can be about 50 mm or greater, about 70 mm or greater, about 80 mm or greater, about 90 mm or greater, about 100 mm or greater, about 110 mm or greater, about 120 mm or greater, about 130 mm or greater, about 150 mm or greater, about 170 mm or greater, about 200 mm or less, about 180 mm or less, about 160 mm or less, about 140 mm or less, about 120 mm or less, about 100 mm or less, about 90 mm or less, or about 80 mm or less. In all respects, the width W can be in the range of about 50 mm to about 200 mm, about 70 mm to about 180 mm, about 70 mm to about 160 mm, about 80 mm to about 140 mm, about 90 mm to about 120 mm, about 100 mm to about 110 mm, or any range or subrange thereof. Example dimensions (length × width) include 100 mm × 50 mm, 150 mm × 75 mm, and 200 mm × 100 mm. Therefore, the area of ​​the first main surface 105 or the second main surface 107 can be 5000 mm². 2 Or larger, 7000 mm 2 Or larger, 10000 mm 2 Or larger, 15000 mm 2 Or larger, 20000 mm 2 Or larger, 25000 mm 2 Or larger, 30,000 mm 2 Or larger, 35000 mm 2 Or larger, or 40,000 mm 2Or larger. As the examples here demonstrate, the dimensions of the piezoelectric element (e.g., a thickness of 120 µm or less and / or corresponding to a thickness greater than 5000 mm) 2 (or larger area size) can unexpectedly improve the low-frequency performance of piezoelectric loudspeakers.

[0043] In all aspects, such as Figure 1 As shown, the piezoelectric device 102 of the piezoelectric loudspeaker 101 may have a single piezoelectric layer as piezoelectric layer 103. In various aspects, such as Figure 1 As shown, the piezoelectric layer 103 may be a single ceramic ribbon. In various respects, the piezoelectric layer 103 may be a sintered ceramic ribbon. As used herein, "sintering" refers to a ceramic matrix material that has been heated to a temperature below its melting point, wherein the material is able to diffuse across the boundary between adjacent particles to form a mechanical bond between them. Without being bound by theory, sintered ceramic ribbons may have improved mechanical strength and / or dimensional stability compared to other methods of forming layers (e.g., physical vapor deposition, sputtering). Furthermore, the piezoelectric device 102 of the piezoelectric speaker 101 may have a single piezoelectric layer as piezoelectric layer 103, which is a single sintered ceramic ribbon.

[0044] Throughout this disclosure, "piezoelectric" refers to a material capable of converting applied electrical energy into mechanical energy (e.g., vibration). For example, see reference... Figure 1Applying electrical energy to the piezoelectric layer 103 via the electrodes 123 and 133 drives the piezoelectric body to vibrate, which, combined with the diaphragm 153, produces sound that can be recognized by the user and / or appreciated aesthetically. In various aspects, the piezoelectric layer 103 may comprise lead zirconate titanate (PZT), lead magnesium niobate-lead titanate (PMN-PT), alkali metal niobates (e.g., sodium niobate and / or potassium niobate (KNN)), zinc oxide (ZnO), aluminum nitride (AlN), quartz, tourmaline, topaz, lanthanum magnesium ore, gallium orthophosphate, lithium niobate, lithium tantalate, beryl ore, barium titanate, bismuth titanate, alkali metal bismuth titanate, potassium niobate, sodium tungstate, alkali metal barium niobate, alkali metal lead niobate, bismuth ferrite, or combinations thereof. In other aspects, the piezoelectric layer includes ceramic materials such as lead zirconate titanate (PZT), lead magnesium niobate-lead titanate (PMN-PT), barium titanate, bismuth titanate, alkali metal bismuth titanate, alkali metal niobates (e.g., sodium niobate and / or potassium niobate (KNN)), potassium niobate, sodium tungstate, alkali metal barium niobate, alkali metal lead niobate, zinc oxide (ZnO), bismuth ferrite, or combinations thereof. In various aspects, the piezoelectric layer 103 may be a transition metal dichalcogenide (TMD), such as a ceramic TMD comprising one or more of the materials mentioned above in the preceding sentence. Exemplary aspects of the piezoelectric layer include lead zirconate titanate (PZT) and alkali metal niobates (e.g., sodium niobate and / or potassium niobate (KNN)). As used herein, "ceramic" has one or more crystalline phases and includes both ceramic and glass ceramic, wherein the glass ceramic has one or more crystalline phases and an amorphous residual glass phase.

[0045] like Figure 1 As shown, the first electrode 123 of the pair of electrodes 123 and 133 is in electrical contact with the piezoelectric layer 103. The first electrode 123 may include a third main surface 125 and a fourth main surface 127 opposite to the third main surface 125. In various respects, as shown, the fourth main surface 127 of the first electrode 123 may be disposed above and / or in physical contact with the first main surface 105 of the piezoelectric layer 103. Furthermore, as... Figure 1 As shown, the second electrode 133 of the pair of electrodes 123 and 133 is in electrical contact with the piezoelectric layer 103. The second electrode 133 may include a fifth main surface 135 and a sixth main surface 137 opposite to the fifth main surface 135. In various aspects, as shown, the fifth main surface 135 of the second electrode 133 may be disposed above and / or in physical contact with the second main surface 107 of the piezoelectric layer 103. In various aspects, such as Figure 1As shown, the pair electrodes 123 and 133 may be positioned on opposite sides of the piezoelectric layer 103 (e.g., with the piezoelectric layer 103 sandwiched in the middle), but other arrangements are possible. In various respects, one or more of the pair electrodes 123 and 133 may be metallic conductors (e.g., copper, aluminum, silver, gold, platinum group materials or alloys thereof) and / or conductive polymers (e.g., poly(p-phenylenevinylene) (PPV), poly(3,4-ethylenedioxythiophene) (PEDOT), polyacetylene, polypyrrole, polyaniline, polythiophene). In all respects, the thickness of the first electrode 123 and / or the thickness of the second electrode 133 may be about 500 nanometers (nm) or greater, about 1 µm or greater, about 2 µm or greater, about 5 µm or greater, about 20 µm or less, about 15 µm or less, about 10 µm or less, about 8 µm or less, or about 5 µm or less, for example, in the range of about 500 nm to about 20 µm, about 1 µm to about 15 µm, about 2 µm to about 10 µm, about 5 µm to about 8 µm, or any range or subrange thereof.

[0046] like Figure 1 As shown, a piezoelectric layer 103 (e.g., piezoelectric device 102) is disposed above a diaphragm 153. In various aspects, as shown, the piezoelectric layer 103 (e.g., piezoelectric device 102) can be attached to the diaphragm 153 via an adhesive layer 143. The adhesive layer 143 includes a first contact surface 145 and a second contact surface 147 opposite to the first contact surface 145. As shown, the first contact surface 145 may face and / or contact the diaphragm 153. In various aspects, as shown, the second contact surface 147 of the adhesive layer 143 may face and / or contact a third main surface 125 of the first electrode 123. Although in Figure 1 Not explicitly shown, but it should be understood, the first electrode 123 may not extend to the entire area of ​​the first main surface 105, such that the second contact surface 147 of the adhesive layer 143 may face and / or contact the first main surface 105 of the piezoelectric layer 103. In various respects, the thickness of the adhesive layer 143 may be about 500 nanometers (nm) or greater, about 1 µm or greater, about 2 µm or greater, about 5 µm or greater, about 20 µm or less, about 15 µm or less, about 10 µm or less, about 8 µm or less, or about 5 µm or less, for example, in the range of about 500 nm to about 20 µm, about 1 µm to about 15 µm, about 2 µm to about 10 µm, about 5 µm to about 8 µm, or any range or subrange thereof.

[0047] In various aspects, adhesive layer 143 may include one or more of the following: polyolefins, polyamides, halogenated polymers (e.g., polyvinyl chloride or fluoropolymers), elastomers, urethanes, phenolic resins, parylene, polyethylene terephthalate (PET), and polyether ether ketone (PEEK). Examples of polyolefins include low molecular weight polyethylene (LDPE), high molecular weight polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), and polypropylene (PP). Examples of fluoropolymers include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), perfluoropolyether (PFPE), perfluorosulfonic acid (PFSA), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP) polymers, and ethylene tetrafluoroethylene (ETFE) polymers. Examples of elastomers include rubbers (e.g., polybutadiene, polyisoprene, chloroprene rubber, butyl rubber, nitrile rubber) and block copolymers (e.g., styrene-butadiene, high-impact polystyrene, poly(dichlorophosphazene)). In other aspects, adhesive layer 143 may include an optically clear adhesive. In yet another aspect, the optically clear adhesive may include one or more optically transparent polymers: acrylics (e.g., polymethyl methacrylate (PMMA)), epoxy resins, silicones, and / or polyurethanes. Examples of epoxy resins include bisphenol epoxy resins, phenolic epoxy resins, alicyclic epoxy resins, and glycidyl amine epoxy resins. In yet another aspect, the optically clear adhesive may include, but is not limited to, acrylic adhesives, such as 3M 8212 adhesive, or optically clear liquid adhesives, such as LOCTITE optically clear liquid adhesive. Exemplary aspects of optically clear adhesives include transparent acrylics, epoxy resins, silicones, and polyurethanes. For example, optically transparent liquid adhesives may include one or more of the following: LOCTITE AD 8650, LOCTITE AA 3922, LOCTITE EA E-05MR, and LOCTITE UK U-09LV, all of which are sourced from Henkel.

[0048] like Figure 1-2 As shown, the diaphragm 151 may include a seventh main surface 157 facing the piezoelectric layer 103 of the piezoelectric device 102. In various aspects, such as Figure 1 As shown, the seventh main surface 157 of the diaphragm 153 may face the first main surface 105 of the piezoelectric layer 103 of the piezoelectric device 102 and / or the third main surface 125 of the first electrode 123. In various aspects, such as Figure 1As shown, the seventh primary surface 157 of the diaphragm 153 may face and / or contact the adhesive layer 143 (e.g., the first contact surface 145). As also shown, the diaphragm 153 may include an eighth primary surface 155 opposite the seventh primary surface 157, wherein the thickness is defined as the average distance between the two surfaces. In various aspects, the thickness of the diaphragm 153 may be approximately 60 µm or greater, approximately 100 µm or greater, approximately 200 µm or greater, approximately 300 µm or greater, approximately 400 µm or greater, approximately 500 µm or greater, approximately 800 µm or greater, approximately 1 mm or greater, approximately 2 mm or greater, approximately 10 mm or less, approximately 5 mm or less, approximately 2 mm or less, approximately 1 mm or less, approximately 800 µm or less, approximately 600 µm or less, approximately 500 µm or less, or approximately 400 µm or less. In all aspects, the thickness of the diaphragm 153 can be in the range of about 60 µm to about 5 mm, about 100 µm to about 2 mm, about 200 µm to about 1 mm, about 300 µm to about 800 µm, about 400 µm to about 600 µm, or any range or subrange thereof. In all aspects, the thickness of the diaphragm 153 can be greater than the thickness 109 of the piezoelectric layer 103. Furthermore, as... Figure 1-2 As shown, the area of ​​the diaphragm 153 (e.g., the seventh main surface 157 or the eighth main surface 155) may be larger than the area of ​​the piezoelectric layer 103 (e.g., the first main surface 105 or the second main surface 107). Although not shown, it should be understood that the diaphragm is attached to and / or supported by a relatively rigid component of a larger device (e.g., a consumer electronic device discussed below) such that the diaphragm 153 can vibrate and produce sound that can be perceived by the user and / or appreciated aesthetically.

[0049] In all respects, the material of the diaphragm 153 is not particularly limited and may include glass-based materials, metallic materials, ceramic-based materials, polymer-based materials, or natural materials (e.g., paper, wood, cotton, bamboo). As used herein, “glass-based” includes both glass and glass-ceramics, wherein the glass-ceramic has one or more crystalline phases and an amorphous residual glass phase. Glass-based materials (e.g., glass substrates) may include amorphous materials (e.g., glass) and optionally one or more crystalline materials (e.g., ceramics). Exemplary glass-based materials may be alkali-free glass and / or include low contents of alkali metals (e.g., R2O of about 10 mol% or less, wherein R2O includes Li2O, Na2O, and K2O). In all respects, polymer-based materials may include one or more of the following: polyolefins, polyamides, halogenated polymers (e.g., polyvinyl chloride or fluoropolymers), elastomers (e.g., rubber or block copolymers), urethanes, phenolic resins, parylene, polyethylene terephthalate (PET), and polyetheretherketone (PEEK). Example examples of polyolefins include low molecular weight polyethylene (LDPE), high molecular weight polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), and polypropylene (PP). Example examples of fluoropolymers include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF), perfluoropolyether (PFPE), perfluorosulfonic acid (PFSA), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP) polymers, and ethylene tetrafluoroethylene (ETFE) polymers. Example examples of elastomers include rubbers (e.g., polybutadiene, polyisoprene, chloroprene rubber, butyl rubber, nitrile rubber) and block copolymers (e.g., styrene-butadiene, high-impact polystyrene, poly(dichlorophosphazene)). In various respects, polymer-based materials may comprise polystyrene, poly(methyl methacrylate), or poly(ethylene terephthalate). Exemplary aspects of the diaphragm include glass-based materials, rubber, polystyrene, poly(methyl methacrylate), and poly(ethylene terephthalate).

[0050] As used herein, the amplitude of sounds at various frequencies is measured using a sound level meter and reported as sound pressure level (SPL) in decibels (dB) at a distance of 50 cm from the diaphragm. Unless otherwise specified and discussed in the examples below, the piezoelectric device 102 is attached to a diaphragm comprising a glass substrate material with a thickness of 500 µm and dimensions of 241 mm × 170 mm. Unless otherwise specified, the piezoelectric loudspeaker is driven by a voltage of 10 to 20 volts (e.g., 10 V or 20 V). As used herein, the average “low-frequency” amplitude refers to the arithmetic mean (i.e., the average) of at least 20 amplitude measurements at equal intervals on a logarithmic scale at frequencies from 100 Hz to 1000 Hz. As used herein, the average “high-frequency” amplitude refers to the arithmetic mean (i.e., the average) of at least 25 amplitude measurements at frequencies ranging from 1000 Hz (1 kHz) to 20000 Hz (20 kHz). In all respects, the average low-frequency amplitude can be the mean of 40 amplitude (SPL) measurements at equal intervals on a logarithmic scale. Similarly, the average high-frequency amplitude can be the mean of 40 amplitude (SPL) measurements at equal intervals on a logarithmic scale.

[0051] In all respects, when driven by a voltage of 10 to 20 volts, the piezoelectric loudspeaker can exhibit an average low-frequency amplitude of approximately 60 dB or greater, approximately 62 dB or greater, approximately 64 dB or greater, approximately 65 dB or greater, approximately 66 dB or greater, approximately 68 dB or greater, approximately 70 dB or greater, approximately 71 dB or greater, approximately 73 dB or greater, approximately 75 dB or greater, approximately 78 dB or greater, or approximately 80 dB or greater. In all respects, when driven by a voltage of 10 to 20 volts, the piezoelectric loudspeaker can exhibit an average low-frequency amplitude within or within the following ranges: 60 dB to 90 dB, 62 dB to 88 dB, 64 dB to 86 dB, 65 dB to 84 dB, 66 dB to 83 dB, 68 dB to 82 dB, 70 dB to 81 dB, 71 dB to 80 dB, 73 dB to 79 dB, and 73 dB to 78 dB. In other respects, the average low-frequency amplitude can be measured with a voltage of 10 volts, which can be within one or more of the ranges discussed above in this paragraph. In yet another respect, when driven with a voltage of 10 volts, the average low-frequency amplitude of the piezoelectric loudspeaker can be in the range of 60 dB to 85 dB, 62 dB to 83 dB, 64 dB to 80 dB, 65 dB to 78 dB, 66 dB to 75 dB, 68 dB to 72 dB, or any range or subrange thereof. In other respects, the average low-frequency amplitude can be measured with a voltage of 20 volts, which can be within one or more of the ranges discussed above in this paragraph. In yet another respect, when driven with a voltage of 20 volts, the average low-frequency amplitude of the piezoelectric loudspeaker can be in the range of 60 dB to 90 dB, 63 dB to 88 dB, 65 dB to 86 dB, 68 dB to 85 dB, 70 dB to 84 dB, 73 dB to 83 dB, 75 dB to 83 dB, or any range or subrange thereof. Therefore, the piezoelectric loudspeaker disclosed herein can unexpectedly improve the frequency response, amplitude, and / or sound quality of low-frequency signals.

[0052] As used herein, "A" compared to "B" means a difference of "X" units, i.e., |A – B| ≤ X, which includes B – A ≤ X. In all respects, when a piezoelectric loudspeaker is driven with a voltage of 10 to 20 volts, it can exhibit an average low-frequency amplitude and an average high-frequency amplitude, where the difference between the average low-frequency amplitude and the average high-frequency amplitude can be within 25 dB or less, 22 dB or less, 21 dB or less, 20 dB or less, 19 dB or less, 18 dB or less, 16 dB or less, 14 dB or less, 12 dB or less, 10 dB or less, or 8 dB or less. In all respects, the difference between the average high-frequency amplitude and the average low-frequency amplitude (i.e., the average high-frequency amplitude minus the average low-frequency amplitude) can be in the range of 0 dB to 25 dB, 1 dB to 22 dB, 2 dB to 21 dB, 3 dB to 20 dB, 4 dB to 19 dB, 5 dB to 18 dB, 6 dB to 16 dB, 7 dB to 14 dB, 8 dB to 12 dB, or any range or subrange thereof. Therefore, the piezoelectric loudspeaker of this disclosure can unexpectedly improve the frequency response, amplitude, and / or sound quality of low-frequency signals compared to the performance of high-frequency signals. In other respects, the average low-frequency amplitude and the average high-frequency amplitude can be measured with a voltage of 10 volts, and the difference between them (i.e., the average high-frequency amplitude minus the average low-frequency amplitude) can be in one or more of the ranges discussed above in this paragraph. In other respects, when the piezoelectric loudspeaker is driven with a voltage of 10 volts, the difference between the average high-frequency amplitude and the average low-frequency amplitude can be in the range of 0 dB to 25 dB, 1 dB to 22 dB, 2 dB to 11 dB, 3 dB to 20 dB, 4 dB to 18 dB, 5 dB to 16 dB, 6 dB to 15 dB, 8 dB to 14 dB, 10 dB to 13 dB, or any range or subrange thereof. In other respects, the average low-frequency amplitude and the average high-frequency amplitude can be measured with a voltage of 20 volts, and the difference between them (i.e., the average high-frequency amplitude minus the average low-frequency amplitude) can be in one or more of the ranges discussed above in this paragraph. In other respects, when the piezoelectric loudspeaker is driven with a voltage of 20 volts, the difference between the average high-frequency amplitude and the average low-frequency amplitude can be in the range of 0 dB to 25 dB, 1 dB to 20 dB, 2 dB to 19 dB, 3 dB to 18 dB, 4 dB to 14 dB, 5 dB to 10 dB, 6 dB to 8 dB, or any range or subrange thereof.

[0053] Various aspects of this disclosure may include consumer electronic products. Consumer electronic products may include a front surface, a rear surface, and side surfaces. Consumer electronic products may also include electrical components at least partially within a housing. The electrical components may include a controller, memory, and a display. The display may be located on or near the front surface of the housing. The display may include a liquid crystal display (LCD), an electrophoretic display (EPD), an organic light-emitting diode (OLED) display, or a plasma display panel (PDP). In various aspects, the consumer electronic product may include a cover substrate disposed above the display. In various aspects, the electrical components may include the piezoelectric speaker 101 of this disclosure. Consumer electronic products may include portable electronic devices such as smartphones, tablets, wearable devices, or laptops. Given the size of the speaker, the consumer electronic product may be incorporated into a laptop, television, monitor, appliance, automobile, train, airplane, or other relatively large device.

[0054] The piezoelectric loudspeaker disclosed herein can be incorporated into another article, such as an article having a display (or display-related articles) (e.g., consumer electronics, including mobile phones, tablets, computers, televisions, monitors, etc.), a building article, a transportation article (e.g., automobiles, trains, airplanes, ships, etc.), or an electrical article. Exemplary articles incorporating the piezoelectric loudspeaker disclosed herein... Figure 3-4 shown in . Specifically, Figure 3-4 A consumer electronic device 300 is shown, comprising a housing 302 having a front surface 304, a rear surface 306, and side surfaces 308. Although not shown, the consumer electronic device may include electrical components at least partially or entirely within the housing. For example, the electrical components include at least a controller, memory, and a display. Figure 3-4 As shown, the display 310 may be located on or near the front surface of the housing 302. Consumer electronic devices may include a cover plate 312 on or above the front surface of the housing 302, such that the cover plate is above the display 310. In various aspects, electrical components may include the piezoelectric speaker of this disclosure. In other aspects, the piezoelectric speaker may include a cover plate as the diaphragm of the piezoelectric speaker.

[0055] Various aspects of a method for manufacturing a piezoelectric loudspeaker 101 will now be discussed. In each aspect, the method may include: forming a green ribbon; sintering the green ribbon to form a sintered piezoelectric layer; and attaching the piezoelectric layer (e.g., the sintered piezoelectric layer) (and a pair of electrodes) to a diaphragm (e.g., using an adhesive layer) to form a piezoelectric loudspeaker. It should be understood that one or more of these actions may be omitted, for example, if the green ribbon of the sintered piezoelectric layer already exists (e.g., acquired by purchase or otherwise manufactured). In each aspect, a single sintered ribbon of ceramic may be used as the piezoelectric layer, and / or a single piezoelectric layer may be used to form the piezoelectric loudspeaker.

[0056] In various aspects, forming a green belt may include forming a slurry by mixing raw materials (e.g., ceramic particles, binder, solvent, dispersant, defoamer, and / or plasticizer), which is then cast to form the green belt. In other aspects, the binder may include one or more polymeric materials. The binder may provide mechanical strength to the green belt before and / or during sintering. In various aspects, the binder may be a solvent-compatible polymer, such as acrylic polymers, methacrylate polymers, carbonate-containing polymers, vinyl acetate resins, maleic acid polymers, vinyl butyral resins, vinyl formal resins, vinyl alcohol resins, cellulose resins, or copolymers or combinations thereof. In various aspects, the solvent may be a polar protic solvent, such as water or an alcohol (e.g., methanol, ethanol, isopropanol, acetic acid), or a polar aprotic solvent, such as a ketone (e.g., methyl ethyl ketone, acetone), N,N-dimethylformamide, dimethyl sulfoxide, dimethyl carbonate, methyl ethyl ketone, toluene, anisole, dioxolane, methoxypropyl acetate, or combinations thereof. As used herein, "dispersant" refers to a material that improves particle separation, improves the uniformity of particle distribution, reduces particle aggregation, and / or reduces particle settling. In various aspects, dispersants may include fish oil or commercial dispersants, such as the Hypermer series of dispersants (available from Croda Energy Technologies). As mentioned above, additional components in the slurry may include defoamers and / or plasticizers. For example, plasticizers may include dibutyl carboxylate. Plasticizers may include dibutyl phthalate, dibutyl adipate, dibutyl maleate, polyethylene glycol, and combinations thereof. In other aspects, viscosity modifiers may include dibutyl phthalate. Casting may include the use of a scraper or other methods known in the art.

[0057] In various aspects, sintering green belts to form a piezoelectric layer may include heating the green belt with one or more heaters to remove organic material from the green belt, and then sintering the particles from the green belt to form the piezoelectric layer. In other aspects, the green belt may be heated in one or more furnaces (e.g., annealing furnaces), for example, conveyed on a firing plate, but long green belts may be conveyed using a roller system with a span greater than one or more furnaces. In yet another aspect, one or more spatial regions within one or more furnaces may be used to control the temperature distribution exposed to the green belt.

[0058] In various aspects, the electrodes can be attached to the piezoelectric layer by melting metal foil or otherwise adhering electrode material to the piezoelectric layer. In various aspects, as discussed above, methods may include using an adhesive layer to attach a single piezoelectric layer (e.g., a single sintered piezoelectric layer) and a pair of electrodes (e.g., already attached to the piezoelectric layer) to a diaphragm to form a piezoelectric loudspeaker (e.g., see [link to relevant documentation]). Figure 1 ).

[0059] Example

[0060] The following examples will further illustrate these aspects. Examples 1-2 were experimentally manufactured and measured, and the results are shown in Table 1 and... Figure 5 The report states that in Example 1, the piezoelectric layer is a sintered PZT ribbon ceramic with a thickness of 60 µm and dimensions of 50 mm × 100 mm, attached to a glass substrate material with a thickness of 500 µm and dimensions of 241 mm × 170 mm. The piezoelectric speaker in Example 1 is driven by a voltage of 10 volts. The piezoelectric speaker in Example 2 is identical to that in Example 1, except that the piezoelectric layer is 100 µm thick and driven by a voltage of 20 volts.

[0061] Table 1: Performance of Examples 1-2

[0062]

[0063] exist Figure 5 In the diagram, the horizontal axis 501 (e.g., the x-axis) represents the frequency in Hertz (Hz), and the vertical axis 503 (e.g., the y-axis) represents the amplitude as a measurement of sound pressure level in decibels (dB). Curve 505 corresponds to Example 1, and curve 507 corresponds to Example 2. See Table 1 and... Figure 5 As shown, Example 1 (curve 505) has an average low-frequency amplitude greater than 60 dB (e.g., greater than 64 dB or about 66 dB). For Example 1, the difference between the average high-frequency amplitude and the average low-frequency amplitude is less than 24 dB (e.g., less than 20 dB, less than 18 dB, less than 15 dB, or about 13 dB). As shown in Table 1 and Figure 5 As shown, Example 2 (curve 507) has an average low-frequency amplitude greater than 60 dB (e.g., about 64 dB). For Example 2, the difference between the average high-frequency amplitude and the average low-frequency amplitude is less than 24 dB (e.g., less than 20 dB or about 18 dB).

[0064] Example 1 performs slightly better than Example 2, but the difference in piezoelectric layer thickness and driving voltage makes it difficult to draw direct conclusions. However, it can be expected that the amplitude will increase with increasing driving voltage. Therefore, compared to the corresponding properties of Example 1 (driving voltage of 10 volts), Example 1 (driving voltage of 20 volts) has a higher (and smaller) low-frequency amplitude, indicating that reducing the thickness of the piezoelectric layer further improves the low-frequency performance of the piezoelectric layer and / or the piezoelectric speaker.

[0065] Example 3-5 simulates a piezoelectric layer PZT with an elastic modulus of 129 gigapascals and dimensions stated in Table 2, attached to a glass-based diaphragm with an elastic modulus of 71 gigapascals, a thickness of 500 µm, and dimensions of 241 mm × 170 mm. Example 3-5 is simulated using a driving voltage of 20 volts, as indicated in Table 2. The results of Example 3-5 are presented in Table 2, and the results of Example 3-5 are plotted on [the relevant table]. Figure 6 The simulation was performed using ALITA FEM.

[0066] Table 2: Performance of Examples 3-5

[0067]

[0068] exist Figure 6 In the diagram, the horizontal axis 601 (e.g., the x-axis) represents the frequency in Hertz (Hz), and the vertical axis 603 (e.g., the y-axis) represents the amplitude as a sound pressure level measured in decibels (dB). Curve 605 corresponds to Example 3, curve 607 to Example 4, and curve 609 to Example 5. See Table 2 and... Figure 6 As shown, Example 3 (curve 605) has an average low-frequency amplitude greater than 60 dB (e.g., greater than 64 dB, greater than 70 dB, or about 73 dB). For Example 3, the difference between the average high-frequency amplitude and the average low-frequency amplitude is less than 24 dB (e.g., less than 20 dB or about 19 dB). As shown in Table 2 and Figure 6 As shown, Example 4 (curve 607) has an average low-frequency amplitude greater than 60 dB (e.g., greater than 64 dB, greater than 70 dB, or about 80 dB). For Example 4, the difference between the average high-frequency amplitude and the average low-frequency amplitude is less than 24 dB (e.g., less than 20 dB or about 14 dB). As shown in Table 2 and Figure 6 As shown, Example 5 (curve 609) has an average low-frequency amplitude greater than 60 dB (e.g., greater than 64 dB, greater than 70 dB, or about 82 dB). For Example 5, the difference between the average high-frequency amplitude and the average low-frequency amplitude is less than 24 dB (e.g., less than 20 dB, less than 10 dB, or about 8 dB).

[0069] like Figure 6 As shown in Table 2, increasing the area of ​​the piezoelectric layer (from Example 3 to Example 5) increased the average low-frequency amplitude. Specifically, increasing the area by a factor of 4 (from Example 3 to Example 5) increased the average low-frequency amplitude by approximately 10 dB. Furthermore, increasing the area of ​​the piezoelectric layer (from Example 3 to Example 5) reduced the difference between the average high-frequency amplitude and the average low-frequency amplitude, from 19.1 dB to 7.7 dB.

[0070] Table 2: Performance of Example 6 and Comparative Example AA-BB

[0071]

[0072] Comparative Examples AA-BB and Example 6 simulate a piezoelectric layer PZT with an elastic modulus of 129 gigapascals and the dimensions stated in Table 3, attached to a glass-based diaphragm with an elastic modulus of 71 gigapascals, a thickness of 500 µm, and dimensions of 241 mm × 170 mm. Comparative Example AA was simulated using a driving voltage of 10 volts, while Comparative Examples BB and Example 6 were simulated using a driving voltage of 16 volts.

[0073] Comparative Example AA has a much larger thickness (1 mm in Comparative Example AA is 10 times larger than 100 µm in Examples 2-3, and approximately 17 times larger than 60 µm in Example 1) and a much smaller area (8 times smaller than Examples 1-3). Comparing the results at 10 V for Example 1 (see Table 1) and Comparative Example AA (Table 3), the difference between the average high-frequency amplitude and the average low-frequency amplitude in the Comparative Example is worse (i.e., larger). This indicates that the piezoelectric loudspeaker of the present invention improves low-frequency performance compared to high-frequency performance.

[0074] Table 3 also presents the dimensions and average low-frequency amplitude of Example 6 and Comparative Example BB. The volume of the single piezoelectric layer in Example 6 (400 mm²) 3 The stack of four piezoelectric elements stacked together in Comparative Example BB (also 400 mm) 3 The driving voltage and volume are the same. Therefore, Example 6 and Comparative Example BB are directly comparable. The average low-frequency amplitude of Example 6 is more than 13 dB higher than that of Comparative Example BB. In addition, although not shown, it was observed that the amplitude difference is 20 dB or greater for frequencies less than 200 Hz. This indicates that the thinner, larger-area piezoelectric layer of the piezoelectric loudspeaker of this disclosure increases the average low-frequency amplitude compared to a thicker, smaller-area piezoelectric material.

[0075] The piezoelectric loudspeaker can achieve high values ​​of average low-frequency amplitude (e.g., 60 dB or greater, or 64 dB or greater). Furthermore, the piezoelectric loudspeaker can exhibit a low difference between the average high-frequency amplitude and the average low-frequency amplitude (e.g., 24 dB or less, 20 dB or less, or 10 dB or less). As shown in the examples here, the dimensions of the piezoelectric element (e.g., a thickness of 120 µm or less and / or corresponding to a thickness greater than 5000 mm) are... 2Larger or larger areas can unexpectedly improve the low-frequency performance of piezoelectric loudspeakers. Piezoelectric loudspeakers can have a single sintered ceramic (e.g., a strip) as the piezoelectric element. Without being bound by theory, sintered ceramic strips can exhibit improved mechanical strength and / or dimensional stability compared to other methods of forming layers (e.g., physical vapor deposition, sputtering).

Claims

1. A piezoelectric speaker comprising: a diaphragm; a piezoelectric layer disposed over the diaphragm, the piezoelectric layer having a thickness in a range of 20 micrometers to 120 micrometers, a width of 50 millimeters or greater, and a length of 100 mm or greater; and a pair of electrodes in electrical contact with the piezoelectric layer and configured to drive the piezoelectric layer.

2. The piezoelectric speaker of claim 1, wherein the width of the piezoelectric layer is 50 millimeters to 200 millimeters and the length is greater than or equal to the width.

3. The piezoelectric speaker of any one of claims 1 to 2, wherein the length of the piezoelectric layer is 100 millimeters to 200 millimeters.

4. The piezoelectric speaker of any one of claims 1 to 3, wherein the piezoelectric layer comprises lead zirconate titanate or alkali niobate.

5. The piezoelectric speaker of any one of claims 1 to 4, wherein the piezoelectric layer is a single piezoelectric layer.

6. The piezoelectric speaker of any one of claims 1 to 5, wherein the piezoelectric layer is a sintered ceramic ribbon.

7. The piezoelectric speaker of any one of claims 1 to 6, wherein the piezoelectric layer is attached to the diaphragm by an adhesive layer.

8. The piezoelectric speaker of any one of claims 1 to 7, wherein the piezoelectric speaker exhibits an average low frequency amplitude of an average sound over a frequency of 100 hertz to 1000 hertz, when the piezoelectric speaker is driven with a voltage of 10 volts to 20 volts, that is within 25 decibels of an average high frequency amplitude of an average sound over a frequency of 1000 hertz to 20000 hertz.

9. The piezoelectric speaker of claim 8, wherein the average low frequency amplitude of the average sound is within 20 decibels of the average high frequency amplitude of the average sound.

10. The piezoelectric speaker of any one of claims 8 to 9, wherein the average low frequency amplitude of the average sound is within 10 decibels of the average high frequency amplitude of the average sound.

11. The piezoelectric speaker of any one of claims 1 to 7, wherein the piezoelectric speaker exhibits an average low frequency amplitude of an average sound over a frequency of 100 hertz to 1000 hertz, when the piezoelectric speaker is driven with a voltage of 10 volts to 20 volts, that is 60 decibels or greater.

12. The piezoelectric speaker of claim 11, wherein the average low frequency amplitude of the average sound is 64 decibels or greater.

13. A consumer electronic device comprising: a housing comprising a front surface, a back surface, and side surfaces; and electrical components at least partially within the housing, the electrical components comprising a controller, a memory, a display, and a piezoelectric speaker according to any one of claims 1 to 12.

14. A method of manufacturing a piezoelectric speaker comprising: attaching a single piezoelectric layer and a pair of electrodes to a diaphragm using an adhesive to form the piezoelectric speaker, wherein the single piezoelectric layer has a thickness in a range of 20 micrometers to 120 micrometers, a width of 50 millimeters or greater, and a length of 100 mm or greater.

15. The method of claim 14, further comprising sintering the green tape to form the single piezoelectric layer.

16. The method of any one of claims 14-15, wherein the width of the single piezoelectric layer is 50 millimeters to 200 millimeters and the length is greater than or equal to the width.

17. The method of any one of claims 14-16, wherein the length of the single piezoelectric layer is 100 millimeters to 200 millimeters.

18. The method of any one of claims 14-17, wherein the single piezoelectric layer comprises lead zirconate titanate or alkali niobate.

19. The method of any one of claims 14-18, wherein the piezoelectric speaker exhibits an average low frequency amplitude of sound averaged over a frequency of 100 hertz to 1000 hertz that is within 20 decibels of an average high frequency amplitude of sound averaged over a frequency of 1000 hertz to 20000 hertz when the piezoelectric speaker is driven with a voltage of 10 volts to 20 volts.

20. The method of any one of claims 14-18, wherein the piezoelectric speaker exhibits an average low frequency amplitude of sound averaged over a frequency of 100 hertz to 1000 hertz that is 60 decibels or greater when the piezoelectric speaker is driven with a voltage of 10 volts to 20 volts.

21. The method of any one of claims 14-20, wherein the piezoelectric speaker is the piezoelectric speaker of any one of claims 1-13.

Images