WO2015073204A1 - Transducteur paramétrique amélioré et procédés correspondants - Google Patents

Transducteur paramétrique amélioré et procédés correspondants Download PDF

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Publication number
WO2015073204A1
WO2015073204A1 PCT/US2014/062736 US2014062736W WO2015073204A1 WO 2015073204 A1 WO2015073204 A1 WO 2015073204A1 US 2014062736 W US2014062736 W US 2014062736W WO 2015073204 A1 WO2015073204 A1 WO 2015073204A1
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WO
WIPO (PCT)
Prior art keywords
backing plate
ultrasonic
adjacent
ridges
emitter
Prior art date
Application number
PCT/US2014/062736
Other languages
English (en)
Inventor
Elwood Grant NORRIS
Original Assignee
Turtle Beach Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US14/079,399 external-priority patent/US9002043B2/en
Application filed by Turtle Beach Corporation filed Critical Turtle Beach Corporation
Priority to JP2016530192A priority Critical patent/JP2017501616A/ja
Priority to CN201480073022.9A priority patent/CN105917667B/zh
Priority to EP14796971.1A priority patent/EP3069529B1/fr
Priority to ES14796971T priority patent/ES2713191T3/es
Publication of WO2015073204A1 publication Critical patent/WO2015073204A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2217/00—Details of magnetostrictive, piezoelectric, or electrostrictive transducers covered by H04R15/00 or H04R17/00 but not provided for in any of their subgroups
    • H04R2217/03—Parametric transducers where sound is generated or captured by the acoustic demodulation of amplitude modulated ultrasonic waves

Definitions

  • the present disclosure relates generally to parametric speakers. More particularly, some embodiments relate to an ultrasonic emitter.
  • Non-linear transduction results from the introduction of sufficiently intense, audio- modulated ultrasonic signals into an air column.
  • Self-demodulation, or down-conversion occurs along the air column resulting in the production of an audible acoustic signal.
  • This process occurs because of the know n physical principle that when two sound waves with different frequencies are radiated simultaneously in the same medium, a modulated waveform including the sum and difference of the two frequencies is produced by the non-linear (parametric) interaction of the two sound waves.
  • the two original sound waves are ultrasonic waves and the difference between them is selected to be an audio frequency, an audible sound can be generated by the parametric interaction.
  • Parametric audio reproduction systems produce sound through the heterodyning of two acoustic signals in a non-linear process that occurs in a medium such as air.
  • the acoustic signals are typically in the ultrasound frequency range.
  • the non-linearity of the medium results in acoustic signals produced by the medium that are the sum and difference of the acoustic signals.
  • two ultrasound signals that are separated in frequency can result in a difference tone that is within the 60 Hz to 20,000 Hz range of human hearing.
  • an ultrasonic audio speaker includes: a backing plate comprising a first major surface and a conductive region, the backing plate further comprising a plurality of textural elements disposed on the first major surface; a flexible layer disposed adjacent the first major surface of the backing plate, the flexible layer comprising a conductive region and an insulative region, wherein the flexible layer is disposed adjacent the backing plate such that the insulative region is positioned between the backing plate and the conductive region of the flexible layer, and such that there is a volume of air between the flexible layer and surfaces of the textural elements; wherein the backing plate and the flexible layer are each configured to be electrically coupled to a respective one of a pair of signal lines carrying an audio modulated ultrasonic carrier, and further wherein, upon application of the audio modulated ultrasonic carrier the flexible layer is configured to launch a pressure-wave representation of the audio modulated ultrasonic carrier signal into the air.
  • FIG. 1 is a diagram illustrating an ultrasonic sound system suitable for use with the emitter technology described herein.
  • FIG. 2 is a diagram illustrating another example of a signal processing system that is suitable for use with the emitter technology described herein.
  • FIG. 3 is a blow-up diagram illustrating an example emitter in accordance with one embodiment of the technology described herein.
  • FIG, 4 is a diagram illustrating a cross sectional view of an assembled emitter in accordance with the example illustrated in FIG, 3 ,
  • FIG, 5 is a diagram illustrating another example configuration of an ultrasonic emitter in accordance with one embodiment of the technology described herein
  • FIG. 6 ⁇ is a diagram illustrating an example of a simple driver circuit that can be used to drive the emitters disclosed herein.
  • FIG. 6B is a diagram illustrating an example of a simple circuit to generate a bias voltage at the emitter drawing the necessary voltage from the signal itself.
  • the circuit is designed to bias at 300V but other voltages are possible by changing diode ZD 1 .
  • FIG. 6C is a diagram illustrating a cutaway view of an example of a pot core that can be used to form a pot-core inductor.
  • FIG. 7 is a diagram illustrating another example emitter configuration in accordance with one embodiment of the technology described herein.
  • FIG. 8 is a diagram illustrating another example emitter configuration in accordance with one embodiment of the technology described herein.
  • FIG. 9A is a diagram illustrating a cross sectional view of a portion of an irregular surface comprising ridges in accordance with one embodiment of the technology described herein.
  • FIG. 9B is a diagram illustrating a perspective view of a plurality of rows of the surface of one embodiment of the backing plate 104 shown in FIG. 9A.
  • FIG. 9C is a diagram illustrating a perspective view of irregularities formed in the shape of peaks (rather than elongated ridges) used to form an irregular surface.
  • FIG. 10 is a diagram illustrating a cross sectional view of a portion of another embodiment having irregular surface comprising ridges.
  • FIG. 1 1 A illustrates an example dimension for a textured surface in accordance with embodiments described above with reference to FIGS. 9 and 10.
  • FIG, 1 1 B illustrates another example dimension for a textured surface in accordance with embodiments described above with reference to FIGS. 9 and 10.
  • FIG. 12A illustrates a cross sectional view of a lextural element in accordance with one embodiment of the technology described hereim
  • FIG. 12B illustrates a perspective view of the textural element depicted in FIG. 1 2 ⁇ .
  • FIG. 13 is a diagram illustrating an example of a contour having a plurality of textural elements such as those illustrated in FIG. 12.
  • FIG. 14 is a diagram illustrating an example of a contour in which a radiused surface is provided between each of the adjacent ridges.
  • FIG. 15 is a diagram illustrating exemplary dimensions for a textured surface in accordance with embodiments described above with reference to FIGS. 1 2 - 14.
  • FIG. 16A illustrates a cross sectional view of an example textured surface in accordance with embodiments described herein.
  • FIG. 16B illustrates a perspective view of an example textured surface in accordance with embodiments described herein.
  • FIG. 17A is a diagram illustrating a top down view of an example emitter formed in an arcuate configuration.
  • FIG. 17B illustrates a top down view of an example emitter formed in a cylindrical configuration.
  • FIG. 1 8A illustrates a perspective view of an example emitter in an arcuate configuration.
  • FIG. 18B illustrates a perspective view of an example emitter in a cylindrical
  • Embodiments of the systems and methods described herein provide a J-IyperSonic Sound (HSS) audio system or other ultrasonic audio system for a variety of different applications.
  • HSS J-IyperSonic Sound
  • Certain embodiments provide a thin lilm ultrasonic emitter for ultrasonic carrier audio applications
  • FIG. 1 is a diagram illustrating an ultrasonic sound system suitable for use with the systems and methods described herein.
  • audio content from an audio source 2 such as, for example, a microphone, memory, a data storage device, streaming media source, CD, DVD or other audio source is received.
  • the audio content may be decoded and converted from digital to analog form, depending on the source.
  • the audio content received by the audio system 1 is modulated onto an ultrasonic carrier of frequency/!, using a modulator.
  • the modulator typically includes a local oscillator 3 to generate the ultrasonic carrier signal, and multiplier 4 to modulate the audio signal on the carrier signal.
  • the resultant signal is a double- or single-sideband signal with a carrier at frequency fl.
  • signal is a parametric ultrasonic wave or an HSS signal.
  • the modulation scheme used is amplitude modulation, or AM.
  • AM can be achieved by multiplying the ultrasonic carrier by the information-carrying signal, which in this case is the audio signal.
  • the spectrum of the modulated signal has two sidebands, an upper and a lower side band, which are symmetric with respect to the carrier frequency, and the carrier itself.
  • the modulated ultrasonic signal is provided to the transducer 6, which launches the ultrasonic wave into the air creating ultrasonic wave 7.
  • the carrier in the signal mixes with the sideband(s) to demodulate the signal and reproduce the audio content. This is sometimes referred to as self- demodulation.
  • the carrier is included with the launched signal so that self-demodulation can take place.
  • FIG. 2 One example of a signal processing system 10 that is suitable for use with the technology described herein is illustrated schematically in FIG. 2.
  • various processing circuits or components are i llustrated in the order ( relative to the processing path of the signal ) in which they are arranged according to one implementation. It is to be understood that the components of the processing circuit can vary, as can the order in which the input signal is processed by each circuit or component. Also, depending upon the embodiment, the processing system 10 can include more or fewer components or circuits than those shown.
  • n in FIG. 1 is optimized for use in processing two input and output channels (e.g.. a " stereo" signal), w ith various components or circui ts including substantially matching components for each channel of the signal.
  • two input and output channels e.g.. a " stereo" signal
  • w ith various components or circui ts including substantially matching components for each channel of the signal.
  • a single channel e.g., a "monaural” or “mono” signal
  • two channels as illustrated in FIG. 2
  • a greater number of channels e.g., a "monaural" or “mono” signal
  • the example signal processing system 10 can include audio inputs that can correspond to left 12a and right 12b channels of an audio input signal.
  • Equalizing networks 14a, 14b can be included to provide equalization of the signal.
  • the equalization networks can, for example, boost or suppress predetermined frequencies or frequency ranges to increase the benefit provided naturally by the emitter/inductor combination of the parametric emitter assembly.
  • Compressor circuits 16a. 16b can be included to compress the dynamic range of the incoming signal, effectively raising the amplitude of certain portions of the incoming signals and lowering the amplitude of certain other portions of the incoming signals. More particularly, compressor circuits 16a, 16b can be included to narrow the range of audio amplitudes. In one aspect, the compressors lessen the peak-to-peak amplitude of the input signals by a ratio of not less than about 2: 1 . Adjusting the input signals to a narrower range of amplitude can be done to minimize distortion, which is characteristic of the limited dynamic range of this class of modulation systems. In other embodiments, the equalizing networks 14a, 14b can be provided before compressors 16a, 16b, to equalize the signals after compression. In alternative embodiments, the compression can take place before equalization.
  • Low pass filter circuits 18a, 1 8b can be included to provide a cutoff of high portions of the signal, and high pass filter circuits 20a, 20b providing a cutoff of low portions of the audio signals.
  • low pass filters 1 8a, 18b are used to cut signals higher than about 15-20 kHz
  • high pass filters 20a, 20b are used to cut signals lower than about 20- 200 Hz.
  • the high pass filters 20a, 20b can be configured to eliminate low frequencies that, after modulation, would result in deviation of carrier frequency (e.g., those portions of the modulated signal of FIG. 6 that are closest to the carrier frequency). Also, some low frequencies are difficult for the system to reproduce efficiently and as a result, much energy can be wasted trying to reproduce these frequencies. Therefore, high pass filters 20a, 20b can be configured to cut out these frequencies.
  • the low pass filters 18a, 18b can be configured to eliminate higher frequencies that, after modulation, could result in the creation of an audible beat signal with the carrier.
  • a low pass filter cuts frequencies above 15 kHz, and the carrier frequency is approximately 44 kHz, the difference signal will not be lower than around 29 kHz, which is still outside of the audible range for humans.
  • frequencies as high as 25 kHz were allowed to pass the filter circuit, the difference signal generated could be in the range of 19 kHz, which is within the range of human hearing.
  • the audio signals after passing through the low pass and high pass filters, the audio signals are modulated by modulators 22a, 22b.
  • Modulators 22a, 22b mix or combine the audio signals with a carrier signal generated by oscillator 23. For example, in some
  • a single oscillator (which in one embodiment is driven at a selected frequency of 40 kHz to 50 kHz, which range corresponds to readily available crystals that can be used in the oscillator) is used to drive both modulators 22a, 22b.
  • an identical carrier frequency is provided to multiple channels being output at 24a, 24b from the modulators.
  • Using the same carrier frequency for each channel lessens the risk that any audible beat frequencies may occur.
  • Fligh-pass filters 27a, 27b can also be included after the modulation stage.
  • High-pass filters 27a, 27b can be used to pass the modulated ultrasonic carrier signal and ensure that no audio frequencies enter the amplifier via outputs 24a, 24b. Accordingly, in some embodiments, high-pass filters 27a, 27b can be configured to filter out signals below about 25 kHz.
  • FIG. 3 is a blow-up diagram illustrating an example emitter in accordance with one embodiment of the technology described herein.
  • the example emitter shown in FIG. 3 includes one conductive surface 45, another conductive surface 46, an insulating layer 47 and a grating 48.
  • conductive layer 45 is disposed on a backing plate 49.
  • backing plate 49 is a non-conductive backing plate and serves to insulate conductive surface 45 on the back side.
  • conductive surface 45 and backing plate 49 can be implemented as a metalized layer deposited on a non-conductive, or relatively low conductivity, substrate.
  • conductive surface 45 and backing plate 49 can be implemented as a printed circuit board (or other like material) with a metalized layer deposited thereon.
  • conductive surface 45 can be laminated or sputtered onto backing plate 49, or applied to backing plate 49 using various deposition techniques, including vapor or evaporative deposition, and thermal spray, to name a few.
  • conductive layer 45 can be a metalized film.
  • Conductive surface 45 can be a continuous surface or it can have slots, holes, cut-outs of various shapes, or other non-conductive areas. Additionally, conductive surface 45 can be a smooth or substantially smooth surface, or it can be rough or pitted. For example, conductive surface 45 can be embossed, stamped, sanded, sand blasted, formed with pits or irregularities in the surface, deposited with a desired degree of Orange peek or otherwise provided with texture.
  • Conductive surface 45 need not be disposed on a dedicated backing plate 49. Instead, in some embodiments, conductive surface 45 can be deposited onto a member that provides another function, such as a member that is part of a speaker housing. Conductive surface 45 can also be deposited directly onto a wall or other location where the emitter is to be mounted, and so on.
  • Conductive surface 46 provides another pole of the emitter.
  • Conductive surface can be implemented as a metalized film, wherein a metalized layer is deposited onto a film substrate (not separately illustrated).
  • the substrate can be, for example, polypropylene, polyimide, polyethylene terephthalate (PET), biaxially-oriented polyethylene terephthalate (e.g., Mylar, Melinex or Hostaphan), Kapton, or other substrate.
  • the substrate has low conductivity and, when positioned so that the substrate is between the conductive surfaces of layers 45 and 46, acts as an insulator between conductive surface 45 and conductive surface 46.
  • conductive surface 46 (and its insulating substrate where included) is separated from conductive surface 45 by an insulating layer 47.
  • Insulating layer 47 can be made, for example, using PET, axially or biaxially-oriented polyethylene terephthalate, polypropylene, polyimide, or other insulative film or material. To drive the emitter with enough power to get sufficient ultrasonic pressure level, arcing can occur where the spacing between conductive surface 46 and conductive surface 45 is too thin. However, where the spacing is too thick, the emitter won't achieve resonance.
  • insulating layer 47 is a layer of about 0,92 mil in thickness. In some embodiments, insulating layer 47 is a layer from about .90 to about 1 mil in thickness.
  • insulating layer 47 is a layer from about .75 to about 1 .2 mil in thickness. In still further embodiments, insulating layer 47 is as thin as about 0.33 or 0.25 mil in thickness. Other thicknesses can be used, and in some embodiments a separate insulating layer 47 is not provided, for example, some embodiments rely on an insulating substrate of conductive layer 46 (e.g., as in the case of a meta!ized film) to provide insulation between conductive surfaces 45 and 46.
  • an insulating layer 47 is that it can allow a greater level of bias voltage to be applied across the first and second conductive surfaces 45, 46 without arcing. When considering the insulative properties of the materials between the two conductive surfaces 45, 46, one should consider the insulative value of layer 47, if included, and the insulative value of the substrate, if any, on which conductive layer 46 is deposited.
  • a grating 48 can be included on top of the stack.
  • Grating 48 can be made of a conductive or non-conductive material.
  • grating 48 can be the grating that forms the external speaker grating for the speaker. Because grating 48 is in contact in some embodiments with the conductive surface 46, grating 48 can be made using a non-conductive material to shield users from the bias voltage present on conductive surface 46.
  • Grating 48 can include holes 51 , slots or other openings. These openings can be uniform, or they can vary across the area, and they can be thru-openings extending from one surface of grating 48 to the other.
  • Grating 48 can be of various thicknesses. For example, grating 48 can be approximately 60 mils, although other thicknesses can be used. Electrical contacts 52a, 52b are used to couple the modulated carrier signal into the emitter. An example of a driver circuit for the emitter is described below.
  • FIG. 4 is a diagram illustrating a cross sectional view of an assembled emitter in accordance with the example illustrated in FIG. 3.
  • this embodiment includes backing plate 49, conductive surface 45, conductive surface 46 (comprising a conductive surface 46a deposited on a substrate 46b), insulating layer 47 between conductive surface 45 and conductive surface 46a, and grating 48.
  • the dimensions in these and other figures, and particularly the thicknesses of the layers, are not drawn to scale.
  • the emitter can be made to just about any dimension. In one application the emitter is of length, I, 10 inches and its width, ⁇ , is 5 inches although other dimensions, both larger and smaller are possible. Practical ranges of length and width can be similar lengths and widths of conventional bookshelf speakers. Greater emitter area can lead to a greater sound output, but may also require higher bias voltages.
  • Table 1 describes examples of metalized films that can be used to provide conductive surface 46.
  • Low sheet resistance or low ohms/square is preferred for conductive surface 46. Accordingly, films on table I having ⁇ 5 and ⁇ 1 Ohms/Square exhibited better performance than films with higher Ohms/Square resistance. Films exhibiting 2k or greater Ohms/Square did not provide high output levels in development testing.
  • Kapton can be a desirable material because it is relatively temperature insensitive in temperature ranges expected for operation of the emitter.
  • Polypropylene may be less desirable due to its relatively low capacitance.
  • a lower capacitance in the emitter means a larger inductance (and hence a physically larger inductor) is needed to form a resonant circuit .
  • films used to provide conductive surface 46 can range from about 0.25 mil to 3 mils, inclusive of the substrate.
  • conductive surface 46 is the DE 320 Aluminum/Folyimide film available from the Dunmore Corporation. This film is a polyimide-based product, aluminized on two sides. It is approximately 1 mil in thickness and provides ⁇ 1 Ohms/Square. As these examples illustrate, any of a number of different metalized films can be provided as conductive surfaces 45, 46. Metalization is typically performed using sputtering or a physical vapor deposition process. Aluminum, nickel, chromium, copper or other conductive materials can be used as the metallic layer, keeping in mind the preference for low Ohms/Square material. Metalized films together with the backing plate typically have a natural resonant frequency at which they will resonate.
  • their natural resonant frequency can be in the range of approxi mately 30 - 150 kHz.
  • some .33 mil apton films resonate at approximately 54 kHz
  • some 1 .0 mil Kapton films resonate at about 34 kHz.
  • the film and the carrier frequency of the ultrasonic carrier can be chosen such that the carrier frequency matches the resonant frequency of the film/backplate combination. Selecting a carrier frequency at the resonant frequency of the film/backplate combination can increase the output of the emitter.
  • FIG. 5 is a diagram illustrating another example configuration of an ultrasonic emitter in accordance with one embodiment of the technology described herein.
  • the example in FIG. 5 includes conductive surfaces 45 and 46 and grating 48.
  • the difference between the embodiment shown in FIG. 5, and that shown in FIGS. 3 and 4 is that the embodiment shown in FIG. 5 does not include separate insulating layer 47.
  • Layers 45, 46 and 48 can be implemented using the same materials as described above with reference to FIGS. 3 and 4.
  • conductive surface 46 is deposited on a substrate with insulative properties.
  • metalized Mylar or Kapton films like the films shown in Table 1 can be used to implement conductive surface 46, with the film oriented such that the insulating substrate is positioned between conductive surfaces 45, 46.
  • FIG. 6A is a diagram illustrating an example of a simple driver circuit that can be used to drive the emitters disclosed herein.
  • a driver circuit 50 can be provided for each emitter.
  • the driver circuit 50 is provided in the same housing or assembly as the emitter.
  • the driver circuit 50 is provided in a separate housing.
  • This driver circuit is only an example, and one of ordinary skill in the art will appreciate that other driver circuits can be used with the emitter technology described herein.
  • the modulated signal from the signal processing system 10 is electronically coupled to an amplifier (not shown). The amplifier can be part of, and in the same housing or enclosure as driver circuit 50.
  • the amplifier can be separately housed. After amplification, the signal is delivered to inputs Al , A2 of driver circuit 50.
  • the emitter assembly includes an emitter that can be operable at ultrasonic frequencies.
  • the emitter (not shown in FIG. 6) is connected to driver circuit 50 at contacts I > I . D2.
  • An inductor 54 forms a parallel resonant circuit with the emitter.
  • the capacitance of the emitter becomes important, because lower capacitance values of the emitter require a larger inductance to achieve resonance at a desired frequency. Accordingly, capacitance values of the layers, and of the emitter as a whole can be an important consideration in emitter design.
  • a bias voltage is applied across terminals B l , B2 to provide bias to the emitter.
  • Full wave rectifier 57 and filter capacitor 58 provide a DC bias to the circuit across the emitter inputs Dl , D2.
  • the bias voltage used is approximately twice (or greater) the reverse bias that the emitter is expected to take on. This is to ensure that bias voltage is sufficient to pull the emitter out of a reverse bias state.
  • the bias voltage is on the order of 300 - 450 Volts, although voltages in other ranges can be used. For example, 350 Volts can be used.
  • bias voltages are typically in the range of a few hundred to several hundred volts.
  • inductor 54 in parallel with the emitter can provide advantages over series arrangement. For example, in this configuration, resonance can be achieved in the inductor-emitter circuit without the direct presence of the amplifier in the current path. This can result in more stable and predictable performance of the emitter, and less power being wasted as compared to series configuration. Obtaining resonance at optimal system performance can improve the efficiency of the system (that is, reduce the power consumed by the system) and reduce the heat produced by the system.
  • FIG. 6B is a diagram illustrating an example of a simple bias circuit that can be used with the emitters disclosed herein. As would be appreciated by one of ordinary skill in the art, where multiple emitters are used (e.g., for stereo applications), a bias circuit 53 can be provided for each emitter.
  • the bias circuit 53 is provided in the same housing or assembly as the emitter. In other embodiments, the bias circuit 53 is provided in a separate housing.
  • This driver circuit is only an example, and one of ordinary skill in the art will appreciate that other driver circuits can be used with the emitter technology described herein.
  • the modulated signal from the signal processing system 10 is electronically coupled to an amplifier (not shown).
  • the amplifier can be part of, and in the same housing or enclosure as driver circuit 53. Alternatively, the amplifier can be separately housed. After amplification, the signal is delivered to inputs A l , A2 of circuit 53.
  • the emitter assembly includes an emitter that can be operable at ultrasonic frequencies. The emitter is connected to driver circuit 53 at contacts E l , E2.
  • An advantage of the circuit shown in FIG. 5B is that the bias can be generated from the ultrasonic carrier signal, and a separate bias supply is not required.
  • diodes 1 ) 1 -1 ) 4 in combination with capacitors C 1 -C4 are configured to operate as rectifier and voltage multiplier.
  • diodes D1 -D4 and capacitors C 1 -C4 are configured as a rectifier and voltage quadrupler resulting in a DC bias voltage of up to approximately four times the carrier voltage amplitude across nodes El , E2.
  • Other levels of voltage multiplication can be provided using similar, known voltage multiplication techniques.
  • Capacitor C5 is chosen large enough to hold the bias and present an open circuit to the
  • Resistors R l , R2 form a voltage divider, and in combination with Zener diode ZD I , limit the bias voltage to the desired level, which in the illustrated example is 300 Volts.
  • Inductor 54 can be of a variety of types known to those of ordinary skill in the art.
  • inductors generate a magnetic field that can 'leak" beyond the confines of the inductor. This field can interfere with the operation and/or response of the emitter.
  • many inductor/emitter pairs used in ultrasonic sound applications operate at voltages that generate large amounts of thermal energy. Heat can also negatively affect the performance of a parametric emitter.
  • the inductor is physically located a considerable distance from the emitter. While this solution addresses the issues outlined above, it adds another complication.
  • the signal carried from the inductor to the emitter is can be a relatively high voltage (on the order of 160 V peak-to-peak or higher). As such, the wiring connecting the inductor to the emitter must be rated for high voltage
  • the inductor 54 (including as a component as shown in the configurations of FIGS. 6A and 6B) can be implemented using a pot core inductor.
  • a pot core inductor is housed within a pot core that is typically formed of a ferrite material. This confines the inductor windings and the magnetic field generated by the inductor.
  • the pot core includes two ferrite halves 59a, 59b that define a cavity 60 within which the windings of the inductor can be disposed. See FIG. 6C.
  • An air gap G can be included to increase the permeability of the pot core without affecting the shielding capability of the core. Thus, by increasing the size of the air gap G, the permeability of the pot core is increased.
  • an air gap can increase permeability and at the same time reduce heat generated by the pot core inductor, without compromising the shielding properties of the core.
  • a dual-winding step-up transformer is used.
  • the primary 55 and secondary 56 windings can be combined in what is commonly referred to as an autotransformer configuration, Either or both the primary and secondary windings can be contained within the pot core.
  • the air gap of the pot core is selected such that the number of turns in the primary winding 55 present the impedance load expected by the amplifier. In this way, each loop of the circuit can be tuned to operate at an increased efficiency level.
  • Increasing the air gap in the pot core provides the ability to increase the number of turns in inductor element 55 without changing the desired inductance of inductor element 56 (which would otherwise affect the resonance in the emitter loop). This, in turn, provides the ability to adjust the number of turns in inductor element 55 to match the impedance load expected by the amplifier.
  • An additional benefit of increasing the size of the air gap is that the physical size of the pot core can be reduced. Accordingly, a smaller pot core transformer can be used while still providing the same inductance to create resonance with the emitter.
  • step-up transformer provides additional advantages to the present system. Because the transformer "steps-up" from the direction of the amplifier to the emitter, it necessarily “steps-down” from the direction of the emitter to the amplifier. Thus, any negative feedback that might otherwise travel from the inductor/emitter pair to the amplifier is reduced by the step-down process, thus minimizing the effect of any such event on the amplifier and the system in general (in particular, changes in the inductor/emitter pair that might affect the impedance load experienced by the amplifier are reduced).
  • 30/46 enameled Litz wire is used for the primary and secondary windings. Litz wire comprises many thin wire strands, individually Insulated and twisted or woven together.
  • Litz wire uses a plurality of thin, individually insulated conductors in parallel.
  • the diameter of the individual conductors is chosen to be less than a skin-depth at the operating frequency, so that the strands do not suffer an appreciable skin effect loss. Accordingly, Litz wire can allow better performance at higher frequencies.
  • ⁇ bias voltage is applied across terminals B l , B2 to provide bias to the emitter.
  • Full wave rectifier 57 and filter capacitor 58 provide a DC bias to the circuit across the emitter inputs D l , D2.
  • the bias voltage used is approximately twice (or greater) the reverse bias that the emitter is expected to take on. This is to ensure that bias voltage is sufficient to pull the emitter out of a reverse bias state.
  • the bias voltage is on the order of 350- 420 Volts. In other embodiments, other bias voltages can be used.
  • bias voltages are typically in the range of a few hundred to several hundred volts.
  • arcing can occur between conductive layers 45, 46. This arcing can occur through the intermediate insulating layers as well as at the edges of the emitter (around the outer edges of the insulating layers. Accordingly, the insulating layer 47 can be made larger in length and width than conductive surfaces 45, 46, to prevent edge arcing. Likewise, where conductive layer 46 is a metalized film on an insulating substrate, conductive layer 46 can be made larger in length and width than conductive layer 45, to increase the distance from the edges of conductive layer 46 to the edges of conductive layer 45.
  • Resistor III can be included to lower or flatten the Q factor of the resonant circuit.
  • Resistor Rl is not needed in all cases and air as a load will naturally lower the Q. Likewise, thinner Litz wire in inductor 54 can also lower the Q so the peak isn't overly sharp.
  • FIG. 7 is a diagram illustrating another example emitter configuration in accordance with one embodiment of the technology described herein.
  • the emitter in this configuration includes a conductive grating 65 as the bottom layer, an insulating middle layer 47 and an upper conductive layer 46.
  • Layers 46 and 47 can be implemented using the examples for layers 46 and 47 described above with reference to FIGS. 3 and 4.
  • Conductive grating 65 can be made using a conductive material, or a material with a conductive surface or coating. Because conductive grating 65 forms one of the emitter electrodes, an input lead 52b is connected to conductive grating 65.
  • Conductive grating 65 can have a pattern of holes, slots or other openings. In some embodiments, the openings make up approximately 50% of the area of conductive grating 65. In other embodiments, the openings can make up a greater or lesser percentage of the area of conductive grating 65. Conductive grating 65 can be approximately 60 mils in thickness. In other embodiments, conductive grating 65 can be of different thickness.
  • FIG, 8 is a diagram il l ustrating another example emitter con figuration in accordance with one embodiment of the technology described herein. The emitter in this configuration includes a conductive grating 65 as the bottom layer, an insulating middle layer 47 and an upper conductive layer 46 and an upper grating 48. The emitter il lustrated in FIG. 8 is similar to the example illustrated in FIG. 7, with the addition of grating 48.
  • the layers that make up the emitters described herein can be joined together using a number of different techniques. For example, frames, clamps, clips, adhesives or other attachment mechanisms can be used to join the layers together.
  • the layers can be joined together at the edges to avoid interfering with resonance of the emitter films.
  • the conductive surface 45 is provided with an irregular surface.
  • the surface can be embossed, stamped, sanded, sand blasted, formed with pits or irregularities in the surface, deposited with a desired degree of Orange peel " or otherwise provided with texture.
  • conductive surface 45 can comprise a conductive plate or other member that is formed or provided with ridges or other like textural elements to present an irregular surface to the conductive emitter f lm 46.
  • FIG. 9 ⁇ is a diagram illustrating a cross sectional view of a portion of an irregular surface comprising ridges in accordance with one embodiment of the technology described herein.
  • a conductive backing plate 104 is provided with a ridged surface 105.
  • the peaks of ridged surface 105 support conductive layer 46.
  • conductive layer 46 is shown as spaced apart from the peaks of ridged surface 105, conductive layer 46 can rest on or come into contact with the peaks of ridged surface 105.
  • conductive layer 46 comprises a conducting layer 46a and an insulating layer 46b separating conducting layer 46a from the peaks.
  • Fig. 9B is a diagram illustrating a perspective view of a plurality of rows of the surface of one embodiment of the backing plate 104 shown in FIG. 9A.
  • the peaks of ridged surface 1 05 extend in length across all or a portion of the backing plate 1 04.
  • Sections of backing plate 1 04 can be fabricated with elongated textural elements 107 (in this example, substantially uniform ridges) extending roughly in parallel across all or sections of the backing plate 104.
  • the irregularities 1 7 in surface 105 are of shorter lengths.
  • FIG. 9C is a diagram illustrating a perspective view of irregularities formed in the shape of peaks (rather than elongated ridges) used to form an irregular surface.
  • the surface irregularit ies are in the form of square pyram ids ( with a truncated, flattened peak), although rectangular pyramids could also be used.
  • the edges of the surface irregularities e.g., ridges 1 07 of FIG. 9B and pyramids 108 of FIG. 9C
  • FIG. 10 is a diagram illustrating a cross sectional view of a portion of another embodiment having irregular surface comprising ridges.
  • the peaks of the ridged surface 1 1 1 are of different heights.
  • peaks 1 12 are loaded peaks in that they support the emitter layer 46.
  • Shorter peaks 1 14 are unloaded peaks and can be provided at a height chosen to provide a desired air volume between emitter layer 46 and backing plate 104.
  • surface 1 1 1 1 can comprise a plurality of elongated ridges extending across all or sections of backing plate 104.
  • surface 1 1 I can comprise a plurality of square or rectangular pyramids disposed on or forming the surface of backing plate 104.
  • the loaded pyramids can be arranged in rows such that there are rows of loaded pyramids adjacent multiple rows of unloaded pyramids.
  • the loaded pyramids can be arranged such that they are surrounded by unloaded pyramids.
  • FIGS. 1 1 A and 1 I B are diagrams illustrating exemplary dimensions for a textured surface in accordance with embodiments described above with reference to FIGS. 9 and 10.
  • the ridges or pyramids are 8 thousandths in height and arranged at a pitch of 19 thousandths.
  • the width of the flattened mesa at the top of the pyramids is 3 thousandths.
  • the angle at the intersection formed between the sidewal ls of adjacent pyramids is preferably a right angle, although other angles can be used.
  • FIG. 1 A and 1 I B are diagrams illustrating exemplary dimensions for a textured surface in accordance with embodiments described above with reference to FIGS. 9 and 10.
  • the ridges or pyramids are 8 thousandths in height and arranged at a pitch of 19 thousandths.
  • the width of the flattened mesa at the top of the pyramids is 3 thousandths.
  • the angle at the intersection formed between the sidewal ls of adjacent pyramids is preferably a right angle, although other angles
  • the pyramids or ridges can be provided with similar dimensions having a pitch of 1 thousandths, a loaded pyramids height of 8 thousandths, and a peak width of 3 thousandths.
  • the difference in height between loaded pyramids and unloaded pyramids can be relatively small, on the order of 0.25 - 4 thousandths.
  • These dimensions are exemplar) ' and can be varied from application to application however, these examples illustrate that the texture provided by the textural elements can be a fine texture.
  • the height of the ridges were pyramids can range from 5 thousandths to 1 5 thousandths
  • the pitch can range from 1 2 thousandths to 100 thousandths, although in both cases, smaller or larger dimensions can be used.
  • FIG. 1 2 which comprises FIGS. 1 2 ⁇ and 1 2 B, provides yet another alternative embodiment for the textural elements of the backing plate.
  • FIG. 12 A is a cross sectional view of a textural element in accordance with one embodiment of the technology described herein, while FIG. 12 B presents a perspective view.
  • a ridge 120 is provided with a modi fied scalloped top surface 121 .
  • Surface 121 includes a plurality of high points 125 and depressions 127 which provide a contour to the top of the textural element (e.g., ridge 120).
  • a conductive layer 46 positioned above backing plate 104. Although conductive layer 46 is shown as spaced apart from the peaks of ridges 120, conductive layer 46 can rest on or come into contact with the peaks of ridged surface 120 provided that conductive layer 46 comprises an insulating layer 46b between conducting layer 46a and backing plate 104. Although not illustrated, when a bias voltage is applied across the emitter, conductive layer 46 will be drawn into more stable contact with scalloped top surface 121 , causing layer 46 to contact the high points 125 and, with sufficient bias, be drawn down at least partially into the depressions 127 and valleys between the ridges.
  • FIG. 13 is a diagram illustrating an example of a contour having a plurality of textural elements such as those illustrated in FIG. 12.
  • the textural elements are arranged in the form of ridges positioned parallel to one another running across all or part of the backing plate 104.
  • the textural elements meet in a V at the base of each text ral ridge.
  • the angle of the V at the intersection formed between the sidewalls of adjacent pyramids is preferably a right angle, although other angles can be used.
  • the textural elements do not meet in a V-shaped
  • the surface between adjacent ridges 120 is a radius surface (e.g. a U-shaped configuration).
  • a radiused surface 122 is provided between each of the adjacent ridges 120.
  • the surface between adjacent ridges 121 has a flat bottom or floor 123.
  • FIG. 15 An example of this is shown in FIG. 15, in which the ridges 121 slope downward from their respective peaks (a constant slope in this example, although a curved surface can also be used) and meet at a substantially flat valley floor 123. The transition from ridge slope to valley floor can be sharp, or it can be radiused.
  • FIG. 16 is a diagram illustrating exemplary dimensions for a textured surface in accordance with embodiments described above with reference to FIGS. 12 - 15.
  • FIG. 16A presents a cross sectional view looking down along the rows of ridges 120
  • FIG. 16B presents a perspective view looking at a single ridge 120 with a plurality of high points 125 and depressions 127.
  • the ridges 120 are 8 thousandths in height, and are spaced at a pitch of 35 thousandths.
  • each ridge is arranged at a pitch of 35 thousandths; the length and width of the flattened mesa at the top of high points 125 are 3 thousandths and 30 thousandths, respectively; and the depth of the depressions 127 is .0008".
  • the texture provided by the textural elements can be a fine texture.
  • the height of the ridges or pyramids can range from 5 thousandths to 15 thousandths, and the pitch can range from 12 thousandths to 100 thousandths, although in both cases, smaller or larger dimensions can be used.
  • the depth of the channel between ridges or pyramids can be an important factor in determining the resonance of the film/backplate emitter system.
  • the carrier frequency of the modulated ultrasonic signal is chosen to be at or near the resonant frequency of the emitter system for efficient operation.
  • the resonant frequency is preferably greater than 35 kHz.
  • the resonant frequency is preferably greater than 50 kHz.
  • emitter layer 46 can have a natural resonant frequency of anywhere in the range from 30 to 1 50 kHz, although alternatives are possible above and below this range.
  • a ftlm/backplate emitter with a resonant frequency of 80 kHz is used.
  • the air volume between film 46 and backing plate 104 can be adjusted to form a resonant system in the range from 30 to 150 kHz, although other frequencies above and below this range are possible.
  • a carrier frequency of 80 kHz is used and the air volume is configured to give the system resonant frequency of 80 kHz.
  • the air volume will be the dominant factor in determining the resonant frequency.
  • the stiffness of the film will dominate and the air volume can be chosen arbitrarily. In other configurations, they both contribute in near equal amounts. Accordingly, design trade-offs can be considered and less than ideal frequency matches utilized.
  • backing plate 104 can be made from Aluminum or other conductive material.
  • Aluminum is desirable due to its light weight and resistance to corrosion.
  • the Aluminum or other conductive material can be machined (e.g., milled), cast, stamped, or otherwise fabricated to form the desired surface pattern for backing plate 104.
  • the backing plate can be made from plastic or other non-conductive material and then coated in a conductive material such as nickel or aluminum. This non-conductive backing plate can be injection molded, cast, stamped or otherwise fabricated to form the desired surface pattern.
  • the emitter can be manufactured using a number of different manufacturing techniques to join layer 46 to backing plate 104.
  • layer 46 is tensioned along its length and width and fixedly attached to backing plate 104 using adhesives, mechanical fasteners, or other fastening techniques.
  • a relatively flat area around the periphery of backing plate 104 can be provided to present a flat area to which film 46 can he glued or otherwise affixed to backing plate 104.
  • Film 46 can be glued or otherwise secured to backing plate 104 along the entire periphery of backing plate 104 or at selected locations.
  • film 46 can be glued or otherwise secured to backing plate 104 at selected points or locations within the periphery.
  • the tension applied to the film during manufacturing is preferably sufficient tension to smooth the film to avoid wrinkles or unnecessarily excess material. Sufficient tension to allow the film to be drawn to the plate upon the application of the bias voltage uniformly across the area of the backing plate is desired. In some applications the amount of tension can be on the order of 10 PSI, although other tensions can be used.
  • one or more air holes can be provided on the back of backing plate 104 to allow air to escape. This can avoid the buildup of unwanted pressure in the air cavity and avoid “ballooning" of the film upon assembly.
  • the textured conductive surface of the backing plate can be anodized or otherwise provided with a thin coating of insulating material on the top surface.
  • film 46 can be a metallized mylar or kapton film with a conducting surface applied to a polymer or other like insulating film.
  • a bi-layer film e.g. layers 46a, 46b
  • a conducting film without an insulating layer
  • the conductive and non-conductive layers that make up the various emitters disclosed herein can be made using flexible materials.
  • embodiments described herein use flexible metallized films to form conductive layers, and non-metalized films to form resistive layers. Because of the flexible nature of these materials, they can be molded to form desired configurations and shapes. In other embodiments, the layers that make up the emitters can be formed using molded or shaped materials to arrive at the desired configuration or shape.
  • FIG. 17A the layers can be applied to a substrate 74 in an arcuate configuration.
  • FIG. 18A provides a perspective view of an emitter formed in an arcuate configuration.
  • a backing material 71 is molded or formed into an arcuate shape and the emitter layers 72 affixed thereto.
  • Other examples include cylindrical (FIGS. 17b and 18b) and spherical.
  • FIGS. 17b and 18b other shapes of backing materials or substrates can be used on which to form ultrasonic emitters in accordance with the technology disclosed herein.
  • Mylar, kapton and other metalized films can be tensioned or stretched to some extent. Stretching the film, and using the film in a stretched configuration can lend a higher degree of directionality to the emitter. Ultrasonic signals by their nature tend to be directional in nature. However, stretching the films yields a higher level of directionality.
  • Conductive layers can be made using any of a number of conductive materials. Common conductive materials that can be used include aluminum, nickel, chromium, gold, germanium, copper, silver, titanium, tungsten, platinum, and tantalum, Conductive metal alloys may also be used, As noted above, conductive layers 45, 46 can be made using metalized films. These include, Mylar, apton and other like films.
  • emitters disclosed herein can be made of transparent materials resulting in a transparent emitter.
  • Such an emitter can be configured to be placed on various objects to form an ultrasonic speaker.
  • one or a pair (or more) of transparent emitters can be placed as a transparent film over a television screen. This can be advantageous because as televisions become thinner and thinner, there is less room available for large speakers. Layering the emitter(s) onto the television screen allows placement of speakers without requiring additional cabinet space.
  • an emitter can be placed on a picture frame, converting a picture into an ultrasonic emitter.
  • metalized films can also be highly reflective, the ultrasonic emitter can be made into a mirror.
  • module does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, can be combined in a single package or separately maintained and can further be distributed in multiple groupings or packages or across multiple locations.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)

Abstract

L'invention concerne un haut-parleur audio ultrasonore qui comprend une plaque d'appui comprenant une première surface majeure et une région conductrice, la plaque d'appui comprenant en outre une pluralité d'éléments texturaux disposés sur la première surface majeure. Une couche souple disposée de manière adjacente à la première surface majeure de la plaque d'appui comprend une région conductrice et une région isolante, la couche souple étant disposée de manière adjacente à la plaque d'appui de telle sorte que la région isolante est positionnée entre la plaque d'appui et la région conductrice de la couche souple, et de telle sorte qu'il existe un volume d'air entre la couche souple et des surfaces des éléments texturaux.
PCT/US2014/062736 2013-11-13 2014-10-28 Transducteur paramétrique amélioré et procédés correspondants WO2015073204A1 (fr)

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JP2016530192A JP2017501616A (ja) 2013-11-13 2014-10-28 改善されたパラメトリックトランスデューサおよび関連の方法
CN201480073022.9A CN105917667B (zh) 2013-11-13 2014-10-28 超声波音频扬声器和发射器
EP14796971.1A EP3069529B1 (fr) 2013-11-13 2014-10-28 Transducteur paramétrique amélioré ainsi que procédés associés
ES14796971T ES2713191T3 (es) 2013-11-13 2014-10-28 Transductor paramétrico mejorado y métodos relacionados

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US14/079,399 US9002043B2 (en) 2013-02-20 2013-11-13 Parametric transducer and related methods
US14/079,399 2013-11-13

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JP (1) JP2017501616A (fr)
CN (1) CN105917667B (fr)
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EP3878566B1 (fr) * 2018-08-03 2023-07-12 UAB "Neurotechnology" Transducteur électrostatique

Citations (3)

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US4246449A (en) * 1979-04-24 1981-01-20 Polaroid Corporation Electrostatic transducer having optimum sensitivity and damping
US20050244016A1 (en) * 1997-03-17 2005-11-03 American Technology Corporation Parametric loudspeaker with electro-acoustical diaphragm transducer
US20060233404A1 (en) * 2000-03-28 2006-10-19 American Technology Corporation. Horn array emitter

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
CA1277415C (fr) * 1986-04-11 1990-12-04 Lorne A. Whitehead Transducteur electrostatique amelioree au moyen d'une membrane d'elastomere
CN103004234B (zh) * 2010-07-22 2017-01-18 皇家飞利浦电子股份有限公司 参量扬声器的驱动

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4246449A (en) * 1979-04-24 1981-01-20 Polaroid Corporation Electrostatic transducer having optimum sensitivity and damping
US20050244016A1 (en) * 1997-03-17 2005-11-03 American Technology Corporation Parametric loudspeaker with electro-acoustical diaphragm transducer
US20060233404A1 (en) * 2000-03-28 2006-10-19 American Technology Corporation. Horn array emitter

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EP3069529A1 (fr) 2016-09-21
CN105917667B (zh) 2019-06-07
ES2713191T3 (es) 2019-05-20
JP2017501616A (ja) 2017-01-12
CN105917667A (zh) 2016-08-31
EP3069529B1 (fr) 2019-01-02

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