The present disclosure generally relates to systems and methods for generating an audio signal. In some examples the system and methods of generating an audio signal are applied in a mobile, wearable, or portable device. In other examples the system and methods of generating an audio signal are applied in earphones, headsets, hearables, or hearing aids.
U.S. Pat. No. 8,861,752 describes a picospeaker which is a novel sound generating device and a method for sound generation. The picospeaker creates an audio signal by generating an ultrasound acoustic beam which is then actively modulated. The resulting modulated ultrasound signal has a lower acoustic frequency sideband which corresponds to the frequency difference between the frequency of the ultrasound acoustic beam and the modulation frequency. US 20160360320 and US 20160360321 describe MEMS architectures for realizing the picospeaker. US 20160277838 describes one method of implementation of the picospeaker using MEMS processing. US 20160277845 describes an alternative method of implementation of the picospeaker using MEMS processing. The extract the optimal performance of the MEMS picospeaker, the device needs to be placed in a package and connected electrically, mechanically and acoustically to the audio device. In this disclosure we describe examples of packaging the MEMS device using the unique features of the modulated ultrasound picospeaker.
“acoustic signal”—as used in the current disclosure means a mechanical wave traversing either a gas, liquid or solid medium with any frequency or spectrum portion between 10 Hz and 10,000,000 Hz.
“audio” or “audio spectrum” or “audio signal”—as used in the current disclosure means an acoustic signal or portion of an acoustic signal with a frequency or spectrum portion between 10 Hz and 20,000 Hz.
“speaker” or “pico speaker” or “micro speaker” or “nano speaker”—as used in the current disclosure means a device configured to generate an acoustic signal with at least a portion of the signal in the audio spectrum.
“membrane”—as used in the current disclosure means a flexible structure constrained by at least two points.
“blind”—as used in the current disclosure means a structure with at least one acoustic port through which an acoustic wave traverses with low loss.
“shutter”—as used in the current disclosure means a structure configured to move in reference to the blind and increase the acoustic loss of the acoustic port or ports.
“acoustic medium”—as used in the current disclosure means any of but not limited to; a bounded region in which a material is contained in an enclosed acoustic cavity; an unbounded region where in which a material is characterized by a speed of sound and unbounded in at least one dimension. Examples of acoustic medium include but are not limited to; air; water; ear canal; closed volume around ear; air in free space; air in tube or another acoustic channel.
“active demodulation”—as used in the current disclosure means any of but not limited to frequency shift of an ultrasound acoustic signal by modulation of the acoustic impedance of at least one part of the MEMS speaker.
Some embodiments of the present disclosure may generally relate to a speaker device that includes at least one ultrasound speaker (USS) and one shutter. The USS is positioned in a first plane and configured to oscillate along a first directional path and at a first frequency effective to generate an ultrasonic acoustic signal. The shutter is positioned in a second plane that is substantially separated from the first plane. The shutter is configured to modulate the ultrasonic acoustic signal such that an audio signal is generated. The speaker device is connected to a driver device where the driver device supplies at least two electrical signals to operate the speaker device at least one membrane and shutter respectively. The driver device receives an input audio signal from which it generates a modulated audio signal to operate the USS and generate an ultrasonic modulated signal. The driver further operates the shutter at the modulation frequency to demodulate the ultrasonic modulated signal and generate an acoustic audio signal.
Other embodiments of the present disclosure may generally relate to a speaker device comprising a plurality of USS and/or shutters. The array of USS and/or shutters operate either independently or in unison by the driver device. In one example, the driving device is a semiconductor integrated circuit which includes; a controller; a charge pump configured to generate a high voltage signal; a switching unit configured to modulate the high voltage signal. The driving device receives a digital sound data stream and an operating voltage and outputs driving signals for the membrane, and shutter. In some embodiments the USS and shutter operate asynchronously and or independently of each other at one or more frequencies. In other embodiments the USS and shutter operate synchronously at the same frequency. In the synchronous mode of operation, the amplitude of the audio signal is controlled by any of but not limited to; the relative phase of the USS and shutter operation; the amplitude of the shutter operation; the amplitude of the USS operation; any combination of these.
In a further embodiment the USS and shutter are realized as a thin film layer stack where on layer is configured as a USS and one or two layers are configured as a shutter. The thin film stack is structured on a perforated Silicon wafer, where at least one perforation is aligned with at least one USS.
In a further embodiment the perforated Silicon wafer includes at least two conductive through Silicon vias with at least one through Silicon via electrically connected to the USS and at least one through Silicon via electrically connected to the shutter.
In a further embodiment a second perforated cap is attached above the thin film layer stack where at least one perforation in the cap is aligned to a shutter or USS.
In an alternative further the perforated cap includes conductive vias connecting the thin film layers to the external side of the cap.
In an alternative embodiment of the present disclosure the speaker device is composed of a stack of at least two ultrasound transducer chip (UTC) each UTC comprised of one or more membranes, wherein the UTC are attached to each other, and electrically connected. At least one of the membranes in a UTC is configured as an USS and at least a second membrane of a UTC is configured as a shutter.
In a further embodiment of the present disclosure the speaker device is composed of a stack of at least two ultrasound transducer chip (UTC) and between the chips a perforated sheet. Each UTC is comprised of one or more membranes. A first UTC is attached to one side of the perforated sheet where at least one membrane in the UTC is aligned with at least one hole of the perforated sheet and a second UTC is attached to the second side of the perforated sheet with at least one membrane aligned to at least one hole in the perforated sheet. The first and second UTC are electrically connected, wherein the electrical connection is configured as either part of the perforated sheet or alternatively an electrical connection utilizes at least one dedicated perforation hole. In a further embodiment at least one of the membranes in a UTC is configured as an USS and at least a second membrane of a UTC is configured as a shutter.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other examples may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure. This disclosure is drawn, inter alia, to methods, apparatus, computer programs, and systems of generating an audio signal.
In some examples, a speaker device is described that includes a membrane and a shutter. The membrane is configured to oscillate along a first directional path and at a combination of frequencies with at least one frequency effective to generate an ultrasonic acoustic signal. A shutter and blind are positioned proximate to the membrane. In one non limiting example the membrane, the blind, and the shutter may be positioned in a substantially parallel orientation with respect to each other. In other examples the membrane, the blind, and the shutter may be positioned in the same plane and the acoustic signal is transmitted along acoustic channels leading from the membrane to the shutter. In a further example the modulator and or shutter are composed of more than one section.
In some embodiments, the membrane is driven by an electric signal that oscillates at a frequency and hence moves at b Cos(2π*Ωt), where b is the amplitude of the membrane movement, and t is time. The electric signal is further modulated by a portion that is derived from an audio signal a(t). The acoustic signal generated by the membrane is characterized as:
s(t)=b a(t)Cos(2π*Ωt) (1)
Applying a Fourier transform to Equation (1) results in a frequency domain representation
S(f)=b/2*[A(f-Ω)+A(f+Ω)] (2)
Where A(f) is the spectrum of the audio signal. Equation (2) describes a modulated audio signal with an upper and lower side band around a carrier frequency of (Double Side Band-DSB). Applying to the acoustic signal of Equation (1) an acoustic modulator operating at frequency Ω results in
S(t)=b a(t)Cos(2π*Ωt)(I+m Cos(2π*Ωt)) (3)
Where I is the loss of the modulator and m is the modulation function and due to energy conservation I+m<1. In the frequency domain
S′(f)=b/4*[m A(f)+m A(f+2Ω)+A(f-Ω)+A(f+Ω)] (4)
Where b/4*m A(f) is an audio signal. The remaining terms are ultrasound signals where m A(f+2Ω) is at twice the modulation frequency and A(f-Ω)+A(f+Ω) is the original unmodulated signal. Additional acoustic signals may be present due to any but not limited to the following; ultrasound signal from the shutter movement; intermodulation signals due to nonlinearities of the acoustic medium; intermodulation signals due to other sources of nonlinearities including electronic and mechanical.
In one example we use the term “active demodulation” to describe the above functions where a frequency shift of an ultrasound acoustic signal is facilitated by modulation of the acoustic impedance of at least one part of the MEMS speaker.
In one example a speaker device includes at least three electro static active layers or membrane layers; a membrane layer as described in equation (1) which receives a first voltage signal, a shutter or modulator layer as described in equation (3) which receives a second voltage signal and a ground layer. In an alternative example a speaker may include at least two piezo electric active layers; a membrane layer and shutter layer where each layer receives a voltage signal on one side of a membrane and a ground signal on a second side of the membrane.
Examples of materials for layer 121 include but are not limited to; Silicon, Silicon Oxide or other glass materials, Aluminum Oxide or other ceramic materials, PCB or other organic substrates. Examples of perforations 145 include circular, rectangular, or other shapes, with angled walls at angle between 70° to 120° and preferably between 80° to 100°. A perforation 145 can be defined in the substrate prior to layer deposition, or after layer deposition using any off but not limited to; dry etching, wet etching, EDM, laser drill, mechanical drill or combination of these methods. The perforation 145 provides an acoustic aperture traversing from a bottom side of layer 121 to a top side of layer 121. Layer 133 with its corresponding top view 111 is a first spacer layer providing an anchor for the membrane of layer 131. Layer 131 with its corresponding top view 109, are a first membrane layer. In one example layer 131 is configured to be an ultrasound speaker and designed to have a mechanical resonance frequency higher than the resonance frequency of a membrane configured in layer 123 which will comprise the shutter functionality. In an alternative example layer 131 is configured as a shutter and has a lower resonance frequency than a membrane realized in layer 123. Layer 129 with its corresponding top view 107 is a second spacer layer. Layer 125 with its corresponding top view 103 is a third spacer layer. Layer 127 with its corresponding top view 105 is a second membrane layer configured as part of an acoustic modulator. Layers 131 and 123 functionality can be interchanged depending on the relative resonance frequency. A membrane configured to be a shutter will have a lower resonance frequency than the ultrasound speaker. In a further example, a shutter and layer 127 are configured as an acoustic modulator and referenced as an acoustic modulator. The relative vertical movement of the shutter in reference to layer 127 generates sound by constricting an acoustic channel between layer 127 and the shutter and modulating the ultrasound signal of the ultrasound speaker. The order of the assembly of the layers (131, 127, 123) can be interchanged for example (127, 131, 123) or (131, 123, 127) or any other combination. Shutter and ultrasound speaker can be interchanged in assembly order and location in layer stack. A shutter is defined as the layer with lower mechanical resonance and the ultrasound speaker as the layer with the higher resonance frequency. In one example one or more of the membrane layers (131, 127, 123) is configured for electrostatic actuation and a voltage difference is applied between two membrane pairs (131 and 127, 127 and 123). Examples of voltages include but are not limited to 20 Volt, 30 Volt, 40 Volt, larger than 40 Volt. In an alternative example one or more of the membranes (131, 123) is configured for piezo actuation. The membrane is configured with a bottom electrode, a top electrode and voltage is applied between top and bottom electrode. In the following figures the description is focused on the electrostatic implementation but a piezo electric implementation is applicable by additional parallel electrical connections realized using the techniques and architecture described below. Examples of materials for membranes include but are not limited to; metal layers including Aluminum, Nickel, AlSiCu, AlCu; dielectric layers including SiN, SiO2; polySi, Silicon, piezo electric layers including, PZT, AlN, AlScN, KNN.
To sum, we described in one example an audio transducer comprised of a perforated substrate configured with a first side including at least one ultrasound speaker; and at least one acoustic modulator; wherein the acoustic signal generated from the ultrasound speaker is modulated by the acoustic modulator to generate an audio signal; and wherein the substrate includes at least one electrical via providing an electrical connection from the substrate second side to substrate first side. At least one substrate perforation, at least one ultrasound speaker and at least one acoustic modulator are aligned. In a further example at least one electrical via is configured to provide electrical connection from an acoustic modulator or ultrasound speaker on perforated substrate first side and to an electrical pad located at the perforated substrate second side. In an alternative further example at least one perforation of encapsulation substrate, at least one substrate perforation, at least one ultrasound speaker and at least one acoustic modulator are aligned.
In an alternative example an audio transducer comprised of a perforated substrate configured with a first side including at least one ultrasound speaker; and at least one acoustic modulator; wherein the acoustic signal generated from the ultrasound speaker is modulated by the acoustic modulator to generate an audio signal; a perforated encapsulation substrate in contact with one side of the perforated substrate; and wherein the perforated encapsulation substrate includes at least one electrical via providing an electrical connection from the encapsulation substrate second side to encapsulation substrate first side. A further example where at least one substrate perforation, at least one encapsulation substrate perforation, at least one ultrasound speaker and at least one acoustic modulator are aligned. In a further example at least one encapsulation substrate electrical via is configured to provide electrical connection from an acoustic modulator or ultrasound speaker on perforated encapsulation substrate first side and to an electrical pad located at the perforated encapsulation substrate second side.
In an alternative example and with reference to
There is little distinction left between hardware and software implementations of aspects of systems; the use of hardware or software is generally (but not always, in that in certain contexts the choice between hardware and software can become significant) a design choice representing cost versus efficiency tradeoffs. There are various vehicles by which processes and/or systems and/or other technologies described herein can be effected (e.g., hardware, software, and/or firmware), and that the preferred vehicle will vary with the context in which the processes and/or systems and/or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and/or firmware vehicle; if flexibility is paramount, the implementer may opt for a mainly software implementation; or, yet again alternatively, the implementer may opt for some combination of hardware, software, and/or firmware.
The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Versatile Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.).
Those skilled in the art will recognize that it is common within the art to describe devices and/or processes in the fashion set forth herein, and thereafter use engineering practices to integrate such described devices and/or processes into data processing systems. That is, at least a portion of the devices and/or processes described herein can be integrated into a data processing system via a reasonable amount of experimentation. Those having skill in the art will recognize that a typical data processing system generally includes one or more of a system unit housing, a video display device, a memory such as volatile and non-volatile memory, processors such as microprocessors and digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices, such as a touch pad or screen, and/or control systems including feedback loops and control motors (e.g., feedback for sensing position and/or velocity; control motors for moving and/or adjusting components and/or quantities). A typical data processing system may be implemented utilizing any suitable commercially available components, such as those typically found in data computing/communication and/or network computing/communication systems.
The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable”, to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to disclosures containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”. Speaker and picospeaker are interchangeable and can be used in in place of the other.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Number | Date | Country | |
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63396274 | Aug 2022 | US |