SYSTEM AND METHOD FOR GENERATING AN AUDIO SIGNAL
20230247357 · 2023-08-03
Inventors
Cpc classification
H04R2217/03
ELECTRICITY
H04R31/00
ELECTRICITY
International classification
Abstract
Techniques described herein generally relate to generating an audio signal with a speaker. In some examples, a speaker device is described that includes a membrane and a shutter and driver device is configured to receive an audio signal, modulate it and generate electric signals to operate the speaker and generate an acoustic audio signal.
Claims
1. A driver device for operating a speaker comprising: power source; two or more voltage drivers; a controller; wherein the controller is configured to receive a digital audio signal and operate the two or more voltage drivers to generate an audio signal for the speaker.
2. The driver device according to claim 1, where the power source is one of: a setup convertor; a charge pump; or a battery voltage.
3. The driver device according to claim 1, where the power source and voltage driver are combined in one functional unit with an output voltage smaller than the target drive voltage.
4. The driver device according to claim 3, where multiple combined power source and voltage driver are configured as a stack so that the summation of voltages in the stack provides the required drive voltage.
5. The driver device according to claim 1, where the controller is configured to operate by: receiving an audio signal; modulation of the audio signal; wherein at least one voltage driver is configured to provide a voltage according to the modulated audio signal and at least a second voltage driver is configured to provide an oscillating voltage at the modulation frequency.
6. The driver device according to claim 1, where the controller is configured to operate by: receiving an audio signal; predistortion of the audio signal; wherein at least one voltage driver is configured to provide an oscillating voltage at a target frequency with a phase defined by the pre-distorted audio signal and at least a second voltage driver is configured to provide an oscillating voltage at the target frequency.
7. The driver device according to claim 6, where the target frequency is in the range between 100 KHz and 1 MHz.
8. A driver device and speaker structure comprising: a speaker comprising: at least one membrane 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; and a shutter positioned in a second plane that is substantially separated from the first plane; and a driver device comprising: a power source; first and second voltage drivers; a controller; wherein the controller is configured to receive an input audio signal and 1) operate the first voltage driver to generate a modulated audio signal to operate the at least one membrane and 2) operate the second voltage driver to generate an ultrasonic modulated signal and operate the shutter at the modulation frequency to demodulate the ultrasonic modulated signal and generate an acoustic audio signal.
9. The structure according to claim 8, where the power source is any of but no limited to; a setup convertor; a charge pump; a battery voltage.
10. The structure according to claim 8, where the power source and voltage driver are combined in one functional unit with an output voltage smaller than the target drive voltage.
11. The structure according to claim 10, where multiple combined power source and voltage driver are configured as a stack so that the summation of voltages in the stack provides the required drive voltage.
12. The structure according to claim 8, where the controller is configured to operate by; receiving an audio signal; modulation of the audio signal; wherein at least one voltage driver is configured to provide a voltage according to the modulated audio signal and at least a second voltage driver is configured to provide an oscillating voltage at the modulation frequency.
13. The structure according to claim 8, where the controller is configured to operate by; receiving an audio signal; predistortion of the audio signal; wherein at least one voltage driver is configured to provide an oscillating voltage at a target frequency with a phase defined by the pre-distorted audio signal and at least a second voltage driver is configured to provide an oscillating voltage at the target frequency.
14. The structure according to claim 13, where the target frequency is in the range between 100 KHz and 1 MHz.
15. A driver device for operating a speaker, comprising: a controller; a charge pump configured to generate a high voltage signal; a switching unit configured to modulate the high voltage signal, wherein the driver device is configured to receive a digital sound data stream and an operating voltage and to output driving signals to a membrane and shutter of the speaker.
16. The driver device of claim 15, wherein the controller, charge pump and switching unit are part of a semiconductor integrated circuit.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] 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.
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DETAILED DESCRIPTION
[0026] 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.
[0027] 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.
[0028] In some embodiments, the membrane is driven by an electric signal that oscillates at a frequency Ω 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:
i. s(t)=b a(t)cos(2π*Ωt) (1)
[0029] Applying a Fourier transform to Equation (1) results in a frequency domain representation
i. S(f)=b/2*[A(f−Ω)+A(f+Ω)] (2)
[0030] 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 Ω (Double Side Band-DSB). Applying to the acoustic signal of Equation (1) an acoustic modulator operating at frequency Ω results in
i. S(t)=b a(t)cos(2π*Ωt)(l+m cos(2π*Ωt)) (3)
[0031] Where l is the loss of the modulator and m is the modulation function and due to energy conservation l+m<1. In the frequency domain
i. S(f)=B/4*[m A(f)+m A(f+2Ω)+A(f−Ω)+A(f+Ω)] (4)
[0032] 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.
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[0037] The CCPD is operated width an oscillating voltage on charge pump input (405) that will generate a local voltage domain Vdd on local supply capacitor (402). By controlling buffer control signal (409) and output enable (410) the output node (411) is charged to the local Vdd (407) or discharged to local ground (408)
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[0043] The system generates the same resulting output voltage waveform (440) as is
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a. s(t)=cos(2π*Ωt+D) (5)
[0046] where D=f(a(t)) is a phase delay determined by f( ) a function of the input signal. In one example f( ) is a trigonometric function, configured to provide a linear acoustic response related to a(t). The acoustic signal is related to
o(t)=cos(2π*Ωt)*cos(2π*Ωt+D) (6)
where cos(2π*Ωt) is the modulator functionality. Using trigonometric relations, we obtain that the low frequency audio portion of o(t)˜cos(D). Hence a suitable function for f( ) in this example is acos( ) It should be noted, that sin( ) and cos( ) are interchangeable and any fixed phase can be added in equation (6) to either the membrane or modulator without any change in performance. In practice since D is a time delay in the membrane drive signal, D is quantized, where the quantization is determined by the system clock. For example, if the system clock T is 20 MHz, the time delay is quantized by T=1/20E6=50 ns. In alternative example if Tis 50 MHz, the time delay is quantized by 20 ns. The quantization introduces quantization noise. In one example, the quantization noise is reduced using sigma delta modulation represented by the COND block. In a further example, the COND block includes a pre distortion unit, where the pre distortion unit is a memoryless nonlinear block implementing the reciprocity of the nonlinear elements of any off but not limited to; the signal driver; and or the speaker device membrane layer. The resulting signal o( ) is used to drive one or more of the switches providing voltage to the membrane and or modulator CMUT. In a further example, D can be split between both membrane and modulator.
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[0049] In a further example, the methods of operating the driver device include methods for extending the number of bits in the input signal. In one example an input audio signal consists of N bits, providing 2.sup.N levels of audio signal. As described in
[0050] 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 affected (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.
[0051] 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.).
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.