JP2002526004A - Parametric speaker with electro-acoustic diaphragm transducer - Google Patents

Abstract

(57) Abstract: A parametric loud for directly generating a plurality of high frequencies to indirectly generate relatively low frequencies by using a substantially monolithic film transducer substantially larger than the wavelength of the carrier frequency in diameter or cross section. Speaker. The film transducer (33) includes an electrostatic film, an electret film, a PVDF film, an electro-thermo-mechanical film and a flat magnetic configuration. A metal, foam, plastic or wood support structure or stator (31) is used to support the transducer. An alternative configuration includes a movable diaphragm that is pulled along the core member and displaced a short distance within the strong portion of the magnetic field. At least one small mass, flat conducting coil is mounted on the movable diaphragm and aspirates the diaphragm at a desired frequency for generation of a series of compression waves tuned to include the ultrasonic frequency range. Includes two contacts that allow current flow to the coil to create a first magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] Background of the Invention 1. FIELD OF THE INVENTION The present invention relates to transducers for electrostatic loudspeakers. More specifically, the present invention provides
The present invention relates to a parametric speaker converter having a stator element and mounted on a film type diaphragm. This converter involves the electromechanical conversion of a one-stage ultrasonic voltage signal into an ultrasonic compression wave whose value difference corresponds to the compression wave frequency of the new acoustic or subsonic wave. 2. 2. Description of the Related Art Parametric speakers are sound emitting devices that directly emit high frequency ultrasonic waves represented by a carrier frequency and a sideband frequency resulting from modulating the carrier frequency with an audio signal. These various ultrasonic frequencies are demodulated in a non-linear medium such as air to reproduce the modulated audio signal to the actual audio output.
In theory, parametric sound evolves due to the interaction in air (non-linear medium) of two ultrasonic frequencies where the difference between the values is in the audible range. Ideally, the synthetic audible compression wave would emit into the air and sound pure. Regardless of ideal theory, sound generation by acoustic heterodyne for practical applications has not been discovered in the industry for more than 100 years.

Since the generation of audio output extends along the length of the ultrasonic wave propagation, the increase in sound pressure level (SPL) evolves along the ultrasonic beam until the ultrasonic energy is dissipated. Thus, the output of a parametric speaker is similar to the termination firing array of a conventional speaker. Despite some similarities between parametric loudspeakers and conventional loudspeaker systems, audio output comes indirectly from high-energy ultrasonic emissions, rather than cones or diaphragms moving at audio frequencies. Therefore, new and new characteristics have arisen. Some of this unique property is well known, such as the long-range beam effect and the positioning of the sound in the emitting area. Other properties have not been previously recognized and have prevented the realization of commercial parametric loudspeaker systems. The present disclosure, entitled Modulator Processing for Parametric Speaker Systems, simultaneously explores some of these characteristics as part of a fully functional parametric speaker, along with field applications. The parametric loudspeaker of the present invention has a full range of audio output with volume, definition and fidelity comparable to high quality conventional sound systems.

[0003] Prior art efforts in parametric loudspeakers have generally been limited to certain limiting properties and theoretical studies of application of transducer arrays of bimorph piezoelectric transducers that are collectively mounted on a support surface. Was. Each bimorph emitter is individually wired to a signal source. Based on this configuration, there was no commercial development of parametric products in the industry. This was primarily due to the inability to reproduce sound as effectively as other conventional sound systems such as dynamic and electrostatic speaker systems. Even if parametric loudspeakers had other advantages, such as good directivity, they had little commercial success because of their high cost, large amount of power consumption, and poor quality for sound-noisy listeners. Not.

[0004] Parametric loudspeakers rely on the effective coupling of the ambient audio with the unique ultrasonic audio output. As mentioned above, previous theoretical and commercial product research has focused primarily on emitter devices that use bimorph piezoelectric structures, also known as piezoelectric vendors. These devices use two layers of piezoelectric material coupled to each other and driven from the phase. As the length of one layer expands and the other contracts, the output on the plane moves 90 degrees in the direction of expansion / contraction. Although the power of these devices is very high, the actual air movement and connection is rather weak. As such, the superior performance of the bimorph is a secondary feature of the conversion process where local movement of the bimorph is amplified in the surrounding air.
Rely on stages. This is achieved with various air interlocking means consisting of a plate and disk structure corresponding to the wavelength of the frequency whose size is concerned.

To develop meaningful SPLs, many of these devices are spaced along a support plate or other support structure. See, for example, FIG. 6 taken from Tanaka et al., U.S. Pat. No. 4,823,908, which contains a cluster of 500-1400 or more bimorph units. Since each of these devices represents a local emitter, the inventor has discovered that the high drive strength immediately before each device can easily bombard or saturate the air. This phenomenon interrupts the effective demodulation of the audio signal, thereby causing power output losses and severe distortion of the acoustic sound component, as well as other significant adverse effects on the general process of operating a parametric speaker. Also, bimorphs have poor frequency response and have undesirable frequency division.

Prior art efforts to improve SPL in bimorph systems have largely focused on increasing the number of bimorph emitters. It has been found that increasing the number of bimorph emitters results in higher ultrasonic power, but merely exacerbates the problem of air saturation and significant power dissipation. In addition, the inventors have discovered a number of problems with phase matching errors, distortion and bandwidth problems due to device differences, and the associated cost and complexity of using such a large number of individual devices. In fact, the phase relationship of these individual devices is such that the total output of many devices used as a cluster does not simply add up to the expected amount of all devices. For example, it has been experimentally demonstrated that an array of 10 bimorph transducers, each capable of individually generating 120 db of SPL, produces only 125-127 db of total SPL. In particular, this is surprisingly less than 130 db, representing a total of 10 devices, each with a theoretical output of 120 db. As noted above, the inventor believes that this power loss results from phase anomalies and other deficiencies specified in this disclosure.

[0007] Another factor that development researchers have probably relied on bimorph devices for is the recognition that the emitter should be configured with dimensions corresponding to the wavelength of the emitted ultrasonic energy. This follows other types of ultrasound devices, such as electrostatic emitters, which are sized at the wavelength of the lowest frequency involved. Even when using these devices, a large number of devices must be used to achieve a given output. In fact, the necessary S
It has been recognized that the higher the PL, the more emitters must be driven at higher voltage levels. Such logic comes from conventional design perceptions of conventional acoustic systems. However, these conclusions remain parametric.
It does not apply to the relationship with the speaker system.

[0008] In addition to the poor results in parametric systems with bimorph converters, the present invention has recognized other traditional perceptions from conventional audio systems that early researchers in the field of parametric loudspeakers have. It leads to the wrong direction, which is a disappointing result that no parametric speaker was developed. This is reflected in the fact that early researcher efforts were substantially limited to the use of bimorph transducers, which are generally classified as high power devices. The preferential use of bimorph transducers in parametric loudspeakers seems to have been a natural consequence of a similar history in the audio industry. In the audio industry, dynamic speakers (also characterized as high power devices) were significantly preferred over electrostatic speakers.
That is, magnetically driven cones (similar in nature to bimorph drivers and associated air-coupled cones) are popular and generally accepted, as development efforts favor bimorphs and film It seems that it has been aimed within the parametric field away from low power emitter structures such as emitters.

For example, 99% of the sound systems sold worldwide that fall into the dynamic speaker category are represented by magnetic drive units that are mechanically coupled to a cone or similar sound driver. Dynamic speakers operate based on two concepts. The first involves an electromechanical process that converts the voltage signal of the audio signal into mechanical motion. This is done by a magnetic drive, such as a combination of magnets and coils. The second concept pertains to the first concept in which mechanical movement is combined with an acoustic coupling device so as to involve movement of the cone due to compression wave displacement. This is conceptually called a two-stage speaker.

[0010] Such a dynamic speaker is called a high-power device because it can generate a large volume based on the strength of the drive system, especially at low frequencies.
It is also well suited for placement in small rooms, small spaces such as cars. The versatility and simplicity of operation (moving the cone) of the dynamic loudspeaker has been advantageous, and has always been a significant advantage over electrostatic loudspeakers and other audio reproduction systems. Further, the need for expensive and complex audio control systems for mixing, crossover, equalization, and related problems as enumerated in US patent application Ser. No. 08 / 684,311 incorporated herein by reference. Nevertheless, such development took place.

[0011] Despite the robustness of the dynamic speaker market, the electrostatic speaker industry has shown significant commercial potential. However, due to low power output, large size and structural limitations, electrostatic speakers have not gained significant market share. Less than 1%. Despite the clear advantages of electrostatic loudspeakers over dynamic loudspeakers within the audio industry, commercial development research still focuses on high power, magnetically driven dynamic systems.

At present, this trend in the acoustic world seems to have influenced the direction of research within the parametric field of sound reproduction. In particular, virtually all parametric studies before the present inventors have involved the use of bimorph transducers, which are similar in construction to dynamic speakers with high power operation. As mentioned above, bimorph systems have not achieved the results needed to commercialize parametric loudspeaker systems. Due to the lack of volume and quality required for the "high power" type of ultrasonic emitter (bimorph transducer), those skilled in the art will recognize that electrostatic or low power film type emitters cannot be performed in the parametric sound field. It was obviously thought to be. Thus, the use of wide film diaphragms and similar one-stage electrostatic-acoustic conversion systems has not been considered as a suitable transducer for parametric studies.

Acoustic science has long known the use of a movable electrostatic film or film that interlocks with and separates a stator or driver member as a speaker and / or microphone device. A typical configuration of such a device consists of a stretchable mylar (tm) or kapton (tm) film with a metal coating and associated conductors, air gaps or rigid plates separated by an insulating material. An applied voltage, including an acoustic or ultrasonic signal, is transmitted to the capacitive assembly and operates to move the stretchable emitter film to propagate the desired ultrasonic or acoustic compression waves.

The electrostatic speakers are mainly classified into two types. A single end speaker typically consists of a single plate with holes through which sound can pass. The film can be hung in front of or behind the plate and moved away from the plate by spacers. In an ultrasonic emitter, the film is in direct contact with the irregular surface of the plate and is biased so that the film can vibrate in a pocket or cavity. An insulating barrier, either air, plastic film, or similar non-conductive material, is sandwiched between the film and the plate to prevent electrical contact and arcing. Typically, the plate and diaphragm couple to a DC power supply to establish opposite polarity at the metallization and each conductive surface of the plate.

The second main category of electrostatic speakers is represented by a push-pull configuration.
In this case, the loudspeaker has two rigid plates arranged symmetrically on each side of the conductive film. When a voltage is applied, one plate has a negative charge on the film and the opposite plate has a positive charge. When a variable voltage (eg, AC) is transmitted to the converter, the push-pull effect on the film is reinforced, thereby increasing the power output. The theory and structure of a common electrostatic emitter design is Ronald Wa
Gner, Electrostatic Speaker, Audio Armature Press, 1993, discussed in detail.

[0016] Research conducted for many years has resulted in the development of a number of technical improvements to this basic system, but the definition of the components remains substantially the same. Surprisingly, the inventor has found that a one-step conversion process using low power converters such as piezoelectric films, electrostatic films, and other similar film emitters provides significant advantages to parametric speakers. Was found. The following disclosure further refines these concepts and embodiments previously cited in the referenced parent application.

[0017] For that purpose and summary of the invention, the object of the present invention is to apply a film converter parametric field of sound reproduction.

It is another object of the present invention to provide an improved speaker diaphragm that can generate a high amplitude compression wave in response to an electrical stimulus, thereby providing a conventional audio diaphragm.
Eliminates the need for a rigid diaphragm structure for the speaker or ultrasonic transducer.

It is yet another object of the present invention to provide a substantially continuous diaphragm to drive less portions of air for a given system's total output.

Yet another object of the present invention is to provide a transducer that can provide high power while minimizing distortion, phase shift, and harmonic resonance. It is yet another object of the present invention to provide a transducer configured to control the directivity pattern of the primary frequency such that the beam width can expand beyond the diameter of the transducer system.

Yet another object of the present invention is to reduce the weight and rigidity requirements by utilizing a foamed material for the stator elements of the speaker system. Another object of the present invention is to provide a plate or support member that can be operated in a single-end or push-pull configuration.

Another object is to indirectly generate at least one new acoustic or subsonic wave having a commercially acceptable volume by using a magnetically driven thin film emitter. Provides interference between at least two ultrasound signals having different frequencies equal to at least one new sound wave or sub-sonic wave.

It is another object of the present invention to provide a film converter having an array of low power, common emitter sections that operate in phase. A particular object of the present invention is to provide a piezoelectric film having an arcuate emitter portion that is commonly energized through a single contact by a parametric signal source.

Yet another object of the present invention is to drive adjacent areas of ambient air in a controlled manner, typically at levels that do not saturate, but maximize the total system output. It is to provide a substantially continuous diaphragm having an array of arcuate emitter portions.

These and other objects are realized in a method for generating a parametric audio signal based on the correlation of a plurality of ultrasonic frequencies in air as a non-linear medium, said method comprising: Generating an electronic signal consisting of at least two ultrasonic signals having different values within a range; b) an electroacoustic film that couples the electronic signal directly with air as part of a one-stage energy conversion process. C) a step of transmitting the electronic signal of the signal plate directly to mechanical movement as a driver member of a parametric speaker; and d) a vibration as an ultrasonic compression wave. E) mechanically emitting at least two ultrasonic signals from the plate into the air; and e) generating ultrasonic compression waves in the air. Each other by the action, a step for generating a parametric audio output consists.

Another embodiment of the invention is a rigid emitter plate having an outer surface with a plurality of apertures or cavities, and the film can be expanded into the cavities and stretched in response to changes in the electrical input applied at the piezoelectric film. A piezoelectric thin film disposed at the aperture of the emitter plate and producing a compression wave in the surrounding environment by forming an array of arcuate emitter configurations and coupled to the piezoelectric film to provide an applied electrical input A speaker device having electric contact means. The array of arcuate emitter configurations can be preformed or spread to this position by positive or negative pressure.

Another embodiment of the invention is a method for improving parametric audio output, the method comprising: (a) an electronic signal comprising at least two ultrasound signals of different values within an audio frequency range. (B) transmitting the electronic signal to an emitter film transducer diaphragm having an array of arcuate emitter portions formed in the film; and (c) transmitting the electronic signal to the parametric speaker. (D) emitting at least two ultrasonic signals from the diaphragm to the air as ultrasonic compression waves, as a driver member; (E) interacting the ultrasonic compression waves in air to generate a parametric audio output. It is characterized by that.

The present invention also provides a method for improving parametric audio output, the method comprising: (a) generating an electronic signal comprising at least two ultrasonic signals of different values within an audio frequency range. (B) simultaneously transmitting an electronic signal to an array of arcuate emitter portions formed in a common electroacoustic transducer diaphragm; and (c) minimizing ambient air saturation. (D) electromechanically moving the phase of the array of arcuate emitter portions as a driver member of a parametric loudspeaker; e) emitting at least two ultrasonic signals from the diaphragm to the air as ultrasonic compression waves; and (f) converting the ultrasonic compression waves into air. And generating a parametric audio output.

Another embodiment of the present invention provides a method for improving parametric audio output, comprising: (a) an ultrasonic carrier signal and at least one auxiliary ultrasonic signal;
Generating an electronic signal consisting of at least two ultrasonic signals having different values from the carrier signal in the audio frequency; and (b) forming in a common electroacoustic film transducer diaphragm having a primary axis of propagation. Transmitting an electronic signal to an array of arcuate emitter portions to be transmitted; and (c) focusing the ultrasound beam emitted from the outer periphery of the at least one array at a predetermined focusing angle with respect to a primary axis of propagation. Providing an array of emitter portions, generally concave, to provide;
(D) electromechanically moving the phases of the array of arcuate emitter portions as a driver member of a parametric speaker; and (e) transmitting at least two ultrasonic signals from the diaphragm as ultrasonic compression waves. It is described based on the steps of emitting into air and (f) interacting the ultrasonic compression waves in air to produce a parametric audio output.

Another embodiment of the invention is a method and apparatus for an ultrasonic emitter device having a wide frequency range with relatively large diaphragm displacement relative to typical electrostatic diaphragm movement. Is realized by: The device comprises a core member capable of establishing a first magnetic field. Because the movable diaphragm extends along the core member and is offset by a short separation distance from the core member, the diaphragm is displaced diagonally with respect to the core member to an intended range within the strong portion of the magnetic field. be able to. At least one low mass planar conductive coil is disposed on the movable diaphragm and has first and second contacts to allow current to flow through the coil. To draw and move the diaphragm at the desired frequency for the development of a series of compression waves including an ultrasonic frequency range having an audio signal variably interacting with the first magnetic field. , A variable current is applied to the coil.

In another aspect of the invention, the emitter of the parametric loudspeaker comprises a drum consisting of a single emitter film disposed on a common emitter surface having a plurality of apertures, where the apertures are then parallel. Arranged to generate all frequencies that occur along the axis, a nearby vacuum is created in the drum and behind the emitter film, thereby eliminating the generation of spacing waves.

In another aspect of the invention, the emitter is comprised of a drum consisting of a single emitter film disposed on a common emitter surface having a plurality of apertures therein, wherein the drum is pressurized here. Not done.

In still another aspect of the invention, the piezoelectric device has a piezoelectric film as an emitter film,
A drum extending on a sensor surface having an opening can detect a compression wave by detecting an electronic signal generated from the impact of the compression wave on the piezoelectric film.

[0034] Other objects and features of the present invention will be apparent to those of ordinary skill in the art in view of the following detailed description of the preferred embodiments in conjunction with the following drawings. DETAILED DESCRIPTION OF THE INVENTION Reference will now be made to the drawings, which illustrate the present invention, in order to provide that various elements of the invention may be numerically identified and made and used by the skilled artisan. . The following description is merely an example of the present invention, and should not be deemed to limit the following claims.

FIGS. 1 a and 1 b show a prior art parametric speaker 10 using a plurality of piezoelectric bimorph transducers 11. These are between 500 and 150
Used with zero or more bimorph converters. One of the challenges associated with parametric loudspeakers is that when driving air at ultrasonic levels to provide a reasonable conversion efficiency and loudness at the secondary synthesized frequency, the fundamental frequency cannot obtain a louder, Driving air to the shock limit where only the strain component level increases. This impact limit is exacerbated when driving individual small points in the air space. The greater the confined strength, the more likely the impact will occur.

FIG. 1 c is a drawing of a series of bimorph transducers, each driving air at a small point in space 12 and causing an impact. FIG. 1d is a drawing of the film converter 13 of the present invention that drives the air in a uniform manner with distributed drives 14 and reduced shock. FIG. 1e is a diagram showing the waveform of the primary frequency below the shock level 15 and the shock level 16. One embodiment of a large-scale film converter is based on the electrostatic drive principle. Electrostatic type transducers use a conductive backplate having a conductive film proximate to the backplate. Either the film or the backplate is biased, and both the film and the backplate are driven by two polarities of the drive signal. FIG.
It is a top view of the large-scale electrostatic converter which has the back plate 21 with an annular V groove. The design of the backplate may alternatively be concave or convex. FIG.
FIG. 3 is a cross-sectional view of an electrostatic back plate and a diaphragm film.

As compared with the wavelength of the frequency, when a high frequency is emitted from a relatively large diaphragm, the sound wave beam can achieve high directivity such that the high frequency is narrowed down to a tight beam. This produces excessively concentrated directivity and early impact formation of sound waves due to the high intensity constricted in the small air space. By bending the diaphragm, the radiation pattern can be broadened to have a directional window that corresponds to the size of the transducer in width, or to have a sound that expands somewhat wider, to minimize shock-limiting waveforms .

FIG. 2 b shows an electrostatic film converter including a bent back plate 23 and a complementary shaped film diaphragm 22 that solves this problem. Another embodiment of the present invention utilizes a piezoelectric film (PVDF). This film expands and contracts when electrically excited, and therefore must be formed to achieve acoustic output. It should be recognized that these large area transducers include, but are not necessarily limited to, electrostatic films, electret films, and piezoelectric films, such as PVDF, electro-mechanical films and planar magnetic features. An implementation shape of the piezoelectric film 30, such as a modified sine shape, is shown in FIG.
Is shown in FIG. 3a is a modified sinusoidal view of the piezoelectric film 30, which is maintained at a fixed distance from the back plate 31 by 4/1 waves. By separating the backplate from the film by 1/4 of the wavelength, the output of the emitter is increased to 3dB at frequencies where the wavelength is four times the film to backplate spacing. FIG. 3 b shows a shallow modified sinusoidal view of the piezoelectric film 32. FIG. 3 c shows a shallow modified sinusoidal view of the piezoelectric film 32 including the back plate 31.

FIG. 4 shows a diagram of a sine wave shaped piezoelectric film. This shape appears to be efficient in utilizing all of the film. For a sine shape with a height equal to or greater than 1/2 WL, the peaks and valleys can be out of phase with each other. In this case, there is a possibility that a correction means for electrically driving the peak from the valley to the opposite phase is required. FIG. 4a shows a view of a sinusoidal piezoelectric film 33 including a spaced back plate 31. FIG. FIG. 4b shows a diagram of a piezoelectric film in a sinusoidal shape including a back plate and a curvature to increase the directivity angle of the primary frequency. This configuration minimizes impact formation and widens the dispersion window as in the electrostatic example above.

Most ultrasonic emitters and parametric loudspeakers are monopolar in nature in the radiation pattern. Bipolar parametric speaker is PVDF
Can be realized in the present invention by using an open film without a back plate as in FIG. 4, which radiates in a bipolar out-of-phase radiation pattern in the primary frequency range and at the same time for all secondary parametric induction signals. Operates in bipolar common mode. This could be used if one wanted to launch a highly directional in-phase sound in two opposite directions. In this case, implementation with prior art devices is not practical. FIG. 4c shows a diagram of a sinusoidal shaped piezoelectric film used in the bipolar primary frequency / bipolar secondary frequency mode. Another diaphragm shape for a piezoelectric film is either a concave or convex depression structure. This shape can be achieved by thermoforming the film or utilizing a foam support structure to push the film into this shape.
Molding the film into a bent emitter section can be accomplished by pushing or pulling the film into the cavity with positive or negative pressure.
In addition, the film can be pressed into the desired shape by utilizing a foam or plastic support structure.

FIG. 5 shows a diagram of a piezoelectric film 51 including a back plate 52 forming either a concave or a convex shape. FIG. 5a shows a view of a piezoelectric film 51 used for a recessed shape with a concave extension. FIG. 5b shows a diagram of a piezoelectric film 51b used for a concave shape having convex characteristics. It will be apparent to the skilled artisan that many variations can be applied to develop the desired curvature of the piezoelectric film based on the concepts of the present invention. In addition, it is also possible to develop a number of support mechanisms to supply these desired curvatures to the piezoelectric film, such as those applied to the development of parametric output of audio sounds as secondary emissions from primary ultrasonic emissions. is there.

The flexibility of flexible film diaphragms is to provide a number of advantages over conventional rigid bimorph devices. Some of these advantages are described in detail in FIGS. FIG. 6 shows a prior art parametric loudspeaker 60 using a plurality of piezoelectric bimorph transducers 62. As mentioned above, these are between 500 and 1500 to produce an effective parametric output.
Bimorph converters are used. The present disclosure has already identified one deficiency in the use of bimorph emitters due to air saturation in the local emission region directly in front of the transducer surface. FIG. 7 graphically illustrates the cause of this distortion, as well as other defects such as those caused by the prior art parametric array 60 due to phase frequency distortion and mismatch. These inconsistencies, such as the reference phase anomaly, are shown in FIG. 7 at 70, 71 and 72.

It should be noted that these bimorph emitters are stand-alone structures having different physical and electrical properties. In fact, such bimorph transducers may be manufactured from different material batches in different assembly environments. Typically, these bimorph transducers are placed in a common bin and supplied by random selection according to the particular design specifications specified by the customer. As a result, the phase mismatch of the propagating ultrasound 66 causes the disappearance of the phase and other forms of sound and directional distortion indicated by dashed lines 76 and 78. Numeral 78 indicates the bending effect of adjacent ultrasound beams such that the phases of each frequency from each emitter are out of phase. For example, the emitter 70 propagates a wave 66a slightly out of phase with the wave 66b from the emitter 71. Dashed line 78 illustrates the directional shift of the audio output from the parametric loudspeaker resulting from the phase mismatch. The emitter 72 is mounted diagonally as indicated by an acute angle 69 that branches slightly from the vertical axis 77 with respect to the mounting support plate. Repeat again, but not collimated,
Beams propagating from emitters that are not properly phase matched can cause energy loss and distortion. As these factors are augmented by 500 to 1500 emitters combined to form a conventional parametric array, the adverse effects can be significant. In addition, these devices also tend to have many harmonic and anti-resonances that are further distorted in the demodulated audio component of the parametric speaker.

In addition to the phase anomalies identified above, FIG. 7 illustrates the air saturation problem 63 described above. Therefore, one of the problems associated with parametric speakers is:
When driving air at the ultrasonic level to provide reasonable conversion efficiency and loudness, drive the air to an impact limit where the fundamental frequency cannot obtain a louder and only the distortion component level increases. Is mentioned. This shock limit increases when driving small points of air space, such as those generated by the bimorph transducer 73. The greater the confined strength, the more likely the impact will occur. This is especially true for high strength devices such as conventional bimorphs.

The present invention shows that by distributing high levels of energy over a large surface area of the film, the management of bombardment is controlled in contrast to the local emitter elements of a bimorph array transducer. If an array of small bimorph emitters would add 130 dB to the emitters and produce the desired SPL, the desired SPL would be shortened and distortion would be greatly magnified. In accordance with the principles of the present invention, wide emitter films are provided at less than 120 db. However, by distributing the energy over the many small emitter sections of the film, the air is not driven until saturation or impact occurs at a local point in front of the transducer. The conversion efficiency of the parametric output generated by the film emitter is very high and the distortion is substantially reduced. This process differs from prior art techniques that attempt to increase volume by focusing high db output from high intensity emitters such as the bimorph family.

In general, these various concepts describe a method for enhancing parametric audio output based on the interaction of multiple ultrasonic frequencies in air, such as a non-linear medium, where: Are performed through one or more prior art construction types. These steps are as follows: a) Generate an electronic signal comprised of at least two ultrasound signals that fall within the audio frequency range and differ in value.

B) Send an electronic signal to an emitter film transducer diaphragm having an array of arcuate emitter sections formed on the film. c) Electro-mechanical replacement of an array of in-phase arcuate emitter sections as driver elements for parametric loudspeakers.

D) mechanically launching at least two ultrasonic signals from the diaphragm into the air as ultrasonic compression waves interacting in the air to produce a parametric audio output.

While prior art techniques have attempted to increase the SPL output by increasing the db level at the bimorph emitter surface, the present invention extends the energy over a large surface area. This reduces the db level of the compressed wave propagating at points in the space, but increases the SPL due to the large area as an overall effect. In addition, SPL can be increased to a more effective level because distortion is minimized. This represents a conceptual step of limiting the electronic signal with the highest intensity level such that ambient air saturation in the individual arcuate emitter sections is minimized. The following geometries and correlated db levels show a good balance between db emitter levels for film emitters and a wide range of geometries.

Additional steps that are readily implemented in accordance with the concepts of the present invention include providing improved collimation of each beam of ultrasonic energy transmitted from each of the film emitter sections. The direction of the ultrasonic energy can be controlled by the support structure of the back plate. In particular, a single common plate structure provides a high degree of physical positioning of the array of emitter sections. Pre-positioning of the bimorph device requires misalignment of each emitter, leading to misalignment. When all emitter sections are correctly aligned, the ultrasonic emission is collimated. Interference loss due to out-of-phase interactions resulting from non-collimated emissions is significantly reduced. Also, a tighter launch of the ultrasonic energy also provides a more efficient conversion in terms of a virtual vertical array of modulations of the audio signal from the ultrasonic emission. Particularly tighter beam patterns increase the audio SPL along the length of the ultrasound beam to provide a greater concentration for energy modulation.

Another embodiment of the present invention shows a more efficient embodiment of the ultrasonic emitter, FIG.
There is. In the embodiment shown in this orthographic view, the emitter drum transducer 100 is a generally cylindrical object. The sidewall 106 of the emitter drum transducer 100 is desirably a metal or metal alloy. However, the emitter surface 102 that generates the compression waves from the top surface of the emitter drum converter 100 is composed of at least two materials. The outer surface of the emitter surface 102 is
It is composed of a piezoelectric film 104. The piezoelectric film 104 is stimulated by an electronic signal applied to the film, thereby generating a vibration at a desired frequency,
Generate compression waves. A conductive ring 114 is disposed on the piezoelectric film 104 and around the emitter surface 102. The conductive ring 114 is used for the piezoelectric film 1.
14 is used to apply a voltage. Below the piezoelectric film 104, a metal cookie 108 (hereinafter referred to as a disc, see FIG. 8), which will be described later, is preferably arranged.

The emitter drum converter 100 is generally hollow inside and has a back cover 110.
Is closed at the bottom. The emitter drum transducer 100 is generally hermetically sealed to maintain a near vacuum (hereinafter, vacuum) or pressurized state inside the emitter drum transducer 100. Positive pressure in the drum transducer 100, where the diaphragm is separated from the rear plate by 1/4 of the wavelength of the selected frequency, creates a useful backwave. Of course, the rear plate can also be used to absorb the backwave with fiberglass, foam or other sound absorbing material.

To provide a better understanding of the structure of the emitter drum transducer 100, FIG. 9 provides a plan view of the outwardly facing side 126 of the disk 108 located below the piezoelectric film 104 (see FIG. 8). . In an embodiment, the disk 108 is metal,
Generally, a plurality of holes 112 having uniform dimensions are drilled. The hole 112 extends through the thickness of the disk 108 from an inward facing side 128 (see FIG. 10) to an outward facing side 126. If a bidirectional piezoelectric film is used to provide performance prediction and maximum efficiency, the holes 112 are formed in a cylindrical shape. When a unidirectional film is applied, a rectangle as shown in FIG. 16 is preferred.

The hole pattern 112 shown on the disk 108 in FIG. 8 is selected in this case because many holes 112 can be arranged in a certain area. Hole patterns are commonly described as "honeycomb" patterns. The honeycomb pattern is selected because it preferably has a number of holes 112 with parallel axes due to the properties of the acoustic heterodyne. Particularly when generating super-audio frequencies, it is preferable to cause heterodyne interference between the fundamental frequency and the frequency that generates the new sound or subsonic frequency containing the information by carrying the information. Consequently, a large number of fundamental and information-bearing signals that are in close proximity to each other and have the effect of generating a larger amount of new acoustic or subsonic frequencies than if a single pair of fundamental and information-bearing frequencies interfere. In other words, the present invention provides the significant advantage of producing a sufficiently loud volume that is commercially viable. The parallel axis of the frequency emission provides a large prediction when a new sound wave or sub-sound wave is generated.

FIG. 10 provides a useful side and cutaway perspective view of an embodiment of the present invention, including details regarding electrical connections to the emitter drum transducer 100. The sidewall 106 of the emitter drum transducer 100 provides an enclosure for the disk 108 having a plurality of holes 112 therethrough. Piezoelectric film 1
04 is shown in contact with the disk 108. An experiment was performed to determine that it is desirable not to bond the piezoelectric film 104 to the entire exposed surface of the disk 108 with which the piezoelectric film 104 contacts. The various sizes of the fillet of adhesive between the piezoelectric film 104 and the holes 112 will result in the uniform holes 112 producing unequal frequencies. Thus, embodiments only show bonding the outer edge of the piezoelectric film 104 to the disk 108.

The back cover 110 is, in embodiments, provided so that a vacuum or near vacuum can be created within the emitter drum converter 100. Near vacuum is a milliton
is defined as a small pressure suitable for measurement in units of litons. There are several reasons for creating a near vacuum in the emitter drum converter 100. First,
First, the vacuum causes the piezoelectric film 104 to be evenly distributed over the holes 112 on the disk 10.
Attract to 8. The uniformity of the tension of the piezoelectric film 104 disposed on the holes 112 is important to ensure the uniformity of the resonance frequency generated by the piezoelectric film 104 disposed on each hole 112. In effect, each piezoelectric film 104 and hole 1
The twelve combinations form a miniature emitter element or cell 124. By controlling the tension of the piezoelectric film 104 disposed on the disk 108, the cells 124 generally respond uniformly.

A second reason for requiring a vacuum is to eliminate the generation of unexpected “backwave” distortion. In other words, by definition, a compression wave requires the presence of a compression medium in which the compression wave travels. The piezoelectric film 104 is the emitter drum converter 1
If it is possible to generate super-compressive waves in the direction “outward” from 00 in the direction indicated by arrow 130, super-compressive waves will also be generated from piezoelectric film 104, and those super-compressive waves will be as indicated by arrow 132. It is logical to go back into the emitter drum converter 100. As a result, these backwards or backwave distortions interfere with the ability of the piezoelectric film 104 to generate the desired frequency. This interference occurs as the back wave reflects upward from the surface in the emitter drum transducer 100 until the back wave moves upward again through the hole 112 and reflects off the piezoelectric film 104, thus altering its vibration. become. Therefore, by eliminating the medium in which the compression wave moves in the emitter drum converter 100, the vibration of the piezoelectric film 104 is not interfered.

FIG. 10 also shows an electrical element of the frequency electrically connected to the piezoelectric film 104 and transmitted from each cell 124 of the emitter drum converter 100.
It also shows the presence of electrical leads 120 carrying the l presentation. These electrical leads 120 are, of course, electrically coupled to several signal sources 122 as shown.

FIG. 11A is an enlarged side view of the two cells 128 (consisting of the piezoelectric film 104 on the two holes 112) shown in FIG. The piezoelectric film 104 is in a state of being expanded inside the emitter drum converter 100 due to excessive vibration for easy explanation. By comparing with FIG. 11B, the piezoelectric film 104
It can be seen that the piezoelectric film expands out of the emitter drum transducer 100 after inward expansion. Also in this case, the amount of expansion of the piezoelectric film 104 is exaggerated for easy understanding. The actual amount of expansion will be described later.

FIG. 12 is a graph showing the frequency response of the emitter drum transducer 100 generated according to the principles of the embodiment, compared to the amount of movement of the piezoelectric film 104 (as a function of the applied voltage RMS). The emitter drum converter 100 had a near vacuum inside the emitter drum converter 100, provided that the graph of FIG. 11 is an example of a typical result. The membrane (piezoelectric film 104) used in the present embodiment is a vinylidene difluoride resin (PVDF) having a thickness of about 28 mm.
It is. Experimentally, the resonant frequency of this particular emitter drum converter 100 is about 1
With a bandwidth of 1.66% and using a driving voltage of 73.6 V _pp , about 37.
It is shown to be 23 kHz (in this case, the upper and lower 6 dB frequencies are 35.55 kHz and 39.89 kHz, respectively). Piezoelectric film 10
It was also found that the maximum amplitude of the movement of 4 just exceeded about 1 μm. This moving amount corresponds to a sound pressure level (hereinafter, SPL) of 125.4 dB.

This large SPL is an emitter drum converter 100 using PVDF, which in theory is assumed to withstand a drive voltage of 1680 V or 22.8 times the applied voltage.
It is surprising that was generated from. As a result, the theoretical limits of these particular materials used in the emitter drum transducer 100 will result in a surprisingly large SPL of 152.6.

It is important to note that the resonant frequency of the embodiment shown here is a function of various characteristics of the emitter drum converter 100. These properties include, among other things, the thickness of the piezoelectric film 104 stretched over the emitter surface 102 and the diameter of the holes 112 in the emitter disk 108. For example, using a thinner piezoelectric film 104 will result in faster vibration of the piezoelectric film 104 for a particular applied voltage. As a result, the resonance frequency of the emitter drum converter 100 increases.

The advantage of a high resonant frequency is that the desired frequency range can be easily generated if the bandwidth percentage is maintained at about 10% or increased as shown by experimental results. In other words, the human hearing range is about 20 to 20,000.
00 Hz. Therefore, if the bandwidth is wide enough to cover at least 20,000 Hz, acoustic heterodyne can easily generate the entire human hearing range as new sound waves. As a result, a signal having modulated sound information and interfering with the appropriate carrier generates a new sound signal capable of producing an audible sound covering the entire audible spectrum of human hearing.

In addition to using a thin piezoelectric film 104 to increase the resonance frequency, there are other ways that this can be achieved. For example, in an alternative embodiment,
The present invention uses cells 124 having smaller diameter holes 112. Small holes also generate a high resonance frequency for a particular applied drive voltage.

FIG. 13 also illustrates an alternative embodiment for generating frequencies from an emitter drum transducer 116 that has less advantages than embodiments of the present invention, but has substantially the same structure as embodiments of the present invention. The essential difference is that instead of creating a vacuum inside the emitter drum transducer 116, the inside is pressurized.

By changing the pressure generated in the emitter drum converter 116, the resonance frequency can be changed. However, the thickness of the piezoelectric film 104 is an important factor in determining the degree to which pressure can be applied. This is due in part to piezoelectric films made from some copolymers with considerable anisotropy instead of the bidirectional films like PVDF used in the embodiments. An undesired side effect of anisotropic piezoelectric films is that they effectively block vibrations of the film in all directions and can cause asymmetries that cause unwanted distortion of the signals generated therefrom. As a result, PVDF is a preferred material for piezoelectric films because of its significantly lower anisotropy, as well as its much higher yield strength than copolymers.

One drawback of the pressurized emitter drum transducer 116 is unwanted frequency resonances or trajectories. These frequency trajectories are replaced by an emitter drum transducer 1 instead of a vacuum.
The presence of the elastic medium inside 16 may result in the generation of a back wave inside the emitter drum converter 116. However, it was determined that the backwave could be removed by placing a substance that absorbs the backwave inside the emitter drum converter 116. For example, foam rubber 134 or other sound absorbing or attenuating material can remove all frequency trajectories.

Experimental results using a pressurized emitter drum transducer 116 show that at typical selection pressures and drive voltages, the emitter drum transducer 116 operates in a substantially linear region. For example, using PVDF with a thickness of 28 mm, 10 ps
An emitter drum transducer 116 having an internal pressure of i (10 pounds per square inch) is about 43 times less than an emitter drum transducer 116 having an internal pressure of 5 psi.
It was determined that a% higher resonance frequency could be generated. Alternatively, when it was determined that doubling the drive amplitude would also double the amount of PVDF movement, it was confirmed that a general linear operating region was found.

Also, experiments have determined that the pressurized emitter drum converter 116 can achieve a bandwidth of about 20%. Thus, configuring the emitter drum transducer 116 with a resonance frequency dedicated to 100 KHz generates a bandwidth of about 20 KHz sufficient to generate the entire human hearing range. By acoustically attenuating the interior of the emitter drum transducer 116 to prevent backwave distortion or low frequency resonance, the impression of pressurized embodiments also has commercially viable volume levels of embodiments of the present invention. Results can be achieved.

Looking at a specific implementation of an embodiment of the present invention as a practical method, the emitter drum converter 100 can be included, for example, in the system shown in FIG.
This system includes a transmitter or digital ultrasound source 220 to provide a base or carrier wave 221. This carrier 221 is generally called a first ultrasonic wave or a primary wave. The amplitude modulation component 222 is coupled to the output of the ultrasonic generator 220 and is coupled to the fundamental frequency 22 to mix the acoustic or subsonic input signal 223.
1 is received. The acoustic or subsonic signals are provided in analog or digital form and can be music from a conventional signal source 224 or other sound form. If the input signal 223 includes upper and lower sidebands, the filter components are included in the modulator to produce a single sideband output on the modulation carrier frequency.

The emitter drum transducer is shown as a component 225 that emits ultrasonic frequencies f1 and f2 as a new waveform propagated at the surface of transducer 225a. This new waveform interacts in a non-linear medium of air to generate a different frequency 226 as a new sound wave or sub-sonic wave.

The present invention can work as described because the compression waves corresponding to f1 and f2 interfere in air according to the principle of acoustic heterodyne action. It can be said that the acoustic heterodyne effect mechanically causes an electric heterodyne effect generated in a nonlinear circuit. For example, amplitude modulation in electrical circuits is a heterodyne process. The heterodyne process itself is simply creating two new waves, which are the sum and difference of the two fundamental waves.

In acoustic heterodyne action, it has been observed that a new wave equal to the sum and difference of the fundamental waves occurs when at least two ultrasonic compression waves interact or interfere in air. I have. The preferred transmission medium of the present invention is air, since air is a non-linearly responsive, highly compressible medium under different conditions. Presumably, this non-linearity of the air is the reason why no electrical circuit is required to generate the heterodyne process. It goes without saying that any compressible medium can function as a transmission medium if the user is willing to use it.

As described above, two new compression waves corresponding to the sum and difference of the ultrasonic waves f ₁ and f ₂ are generated by the acoustic heterodyne effect. The sum is an inaudible ultrasonic wave and is not shown here because it is not very interesting. On the other hand, the difference can be a sound wave or a sub sound wave and is shown as a compressed wave 226. Is a wave generated in all directions.

In the prior art, difference waves have been successfully generated, but this appears to be limited to nominal volume. In the structure according to the invention, a full volume is generated. A single transducer transmitting a fundamental frequency and a modulated single sideband frequency could project sound at a significant distance and at an impressive volume, but combining multiple co-linear signals would significantly increase the volume . Pointing them at a wall or other reflective surface increased the volume and echoed the wall as if it were the source of the sound itself.

An important feature of the present invention is that the fundamental frequency and the single sideband propagate from the same transducer face, so that the constituent waves are perfectly parallel. Furthermore, the phase alignment is maximized, producing the highest possible level of interference between two different ultrasonic frequencies. Ensuring maximum interference between these waves would allow maximum energy transfer to air molecules and would be the "speaker" radiating element of a parametric speaker. Therefore, the inventor believes that the present invention may have resulted in a surprising volume increase for the audio output signal.

In the embodiment shown in FIG. 14, the emitters are arranged on a single film diaphragm, but this is a preferred embodiment for various reasons. For example, in this system, there is no need to attach a bimorph device to each, and thus the production cost is low.
This single film converter actually produces a plurality of parallel signals. Most importantly, the system is lightweight, compact and has maximum efficiency. The implementation of the present invention, as compared to prior art devices, will always generate a new compression wave with maximum efficiency. It is based on the perfect coaxial relationship obtained when the localization of two different ultrasonic transducers emits a new ultrasonic shape 227 using the same ultrasonic transducer 225 and realizes both ultrasonic compression waves. Because they do not match or exceed it. Propagating coaxially from a single aperture of the emitter drum converter 100 in this manner produces a maximum interference pattern and the most efficient compression wave.

It is an important advantage that a full volume capacity can be obtained with a parametric speaker as compared with a conventional speaker system. Most important is the fact that sound is reproduced from a relatively massless radiating element. There are no direct radiating elements in the interference zone, and therefore no new compression wave generation. This feature of generating sound by acoustic heterodyne effects can substantially eliminate the distortion effects caused by the radiating elements of most conventional loudspeakers. For example, a cone overshoot and a negative overshoot can correct a reproduced signal of a loudspeaker cone that is not pure due to the presence of harmonics or standing waves.

This improvement is very significant compared to the limitations of the conventional speaker diaphragm. For example, elements that radiate physically directly do not have a truly uniform frequency response. The frequency response is correlated with the type of frequency (bass, middle, treble) and is inherently optimal for emission. The shape, shape and dimensions of the speaker are directly
While affecting the inherent characteristics of the loudspeaker, acoustic heterodyne wave generation uses natural air reactions to solve geometric and configuration problems, resulting in a truly uniform frequency response and sound generation be able to. Parametric systems can achieve acceptable amplitude levels of sound, and can compete directly with conventional speakers directly and commercially. This is a result that cannot be realized by the conventional parametric or beat mixing apparatus.

The sound without distortion means that in the embodiment according to the present invention, the phase coherence with the initially recorded sound is maintained. Conventional speaker systems do not have this capability. This is because the frequency spectrum is broken apart by the crossover network due to propagation by the optimum speaker element (woofer, midrange, tweeter). By eliminating this radiating element, the present invention eliminates the need for a conventional crossover network frequency and phase controller and provides a virtual or near point source of sound.

Further, another advantage arises that is directly related to the unique characteristics of the ultrasonic film converter 225. Due to their small size and low mass, such transducers are generally free of many of the limitations and disadvantages of conventional radiating elements used in loudspeakers. Further, since ultrasonic transducers are used at extremely high frequencies, the distortion, harmonics, and other undesirable features found in direct radiating elements that must reproduce sound directly in low, medium, and high frequency ranges. Can be avoided. As a result, many of the acoustically desirable attributes of a relatively distortion-free ultrasonic transducer system can be indirectly converted into sonic and subsonic by-products.

FIGS. 15 and 16 disclose another embodiment of a piezoelectric film diaphragm and support plate that do not require the application of pressure or the use of a drum. Transducer 1 shown
60 includes a base plate 161 and a supported film diaphragm 162 made of a piezoelectric material. The aforementioned voltage can be applied at electrical contacts on the film. The arc-shaped emitter section 165 is formed into a stable structure by molding or thermoforming. Corresponding depressions and openings in the upper surface of the support plate 161 are aligned to receive the face of the film. These indentations are deep enough so that the emitter is free to move and does not interfere with and contact the indentation walls 167. An intermediate surface 168 of the support plate contacts the flat portion 162a of the film to stabilize the film and the emitter and to properly align with the parallel propagation axis 170 as shown. Since the film has a single structure that uniformly responds to the applied voltage and generates a compression wave 172 that is correctly aligned in phase, an in-phase operation occurs.

The material of the support plate 161 can be any rigid material that provides the ability to stabilize the emitter film 162 and operate properly. A conductive plate can be used instead of the contact 163, and a signal voltage can be applied to the piezoelectric film. The illustrated piezoelectric film is a copolymer film and has a unidirectional response across the elongated emitter section, as illustrated by line 174. This is in contrast to interactive films such as PVDF. The unidirectional film has about 80% shape expansion along the transverse direction 174, and therefore has a good response. Increasing the arc emitter 165 increases the surface area and provides a desirable SPL output.

FIG. 17 illustrates another method of implementing the present invention in another method of forming the emitter section 180. In this method, a single flat sheet made of a piezoelectric material is formed by a support plate 183 having a knob 184 having a preferable emitter shape.
Mainly displaces in an arc. As shown, a force F is applied to deform the film in accordance with the bump. This force may be a pulling force applied from the outer periphery of the film to pull the film against the bumps, or another appropriate method may be used. The bumps are preferably made of a foam material so that the piezoelectric film can vibrate according to the applied voltage.

In yet another embodiment of the present invention, an ultrasonic parametric compression wave is created using a foamed stator having an electrostatic diaphragm. FIG. 18 shows a single-ended speaker device 310 that propagates an ultrasonic output 311 in a forward direction 312. The loudspeaker may be coupled to an ultrasonic drive 313 which provides various electronic circuit support elements for providing the desired signal, as described above.

The apparatus includes an electrostatic emitter film 315 responsive to a variable voltage applied to emit an ultrasonic output. This emitter film consists of a plastic sheet and a thin metal coating or other conductive surface. Electrostatic emitter films are well known and have been applied to many capacitive or stratified charging systems, and are hereinafter generally referred to as electrostatic devices. Typically, the plastic sheet is mylar (tm), capron (tm), or other non-conductive composition and serves as an insulator between the metal layer and the stator member 320. A partially conductive surface or coating can be used to uniformly charge the diaphragm surface. The preferred range of resistance is greater than 10K ohms, which reduces charge transfer and prevents build-up of static charge up to arcing. High impedances, such as 100 Mohm, are not uncommon in this application. Obviously, choosing this also affects the capacitance between the two plates.

One of the main features of the embodiment of the present invention is that a foam member is used as the stator 320. The stator acts as a base or rigid component that provides inertia to the lightweight and flexible emitter film 315. This stator is a conductive element that gives the capacitor combination one polarity. The resistance of this component is chosen to help uniform charge transfer to avoid arcing and other adverse effects inherent in electrostatic systems. Preferred compositions exhibiting effective characteristics are conventional static packaging foam materials used as packaging materials for computers and other charge-sensitive contents (commonly known as "conductive foams").
This material acts to discharge static electricity from sensitive components. This material is lightweight and inexpensive, as well as protects components from adverse electrical and electrical exposure. The material is usually molded in conventional foam molding equipment of any shape, density and size.

This material is used in the prior art in a generally limited role (packaging material), whose sole purpose is to protect sensitive components. Like other packaging materials, their use is limited, such as temporary filling to fill the space inside a carton or container, and they are often discarded together with the container as having no independent value. The availability of this material in the electronics market is commonplace, and is evidenced by its massive disposal in landfills worldwide.

These figures show the foaming components of random pockets and cavities. Using available techniques, the voids in the plastic matrix can be made more uniform. Thus, the stator components can be tuned and optimized for specific frequency applications, resonances, and related attributes. The stiffness and rigidity of the foam
The pocket density and wall thickness forming individual voids and pockets are of course correlated with the material properties. Thus, in addition to controlling random versus uniform void sizing,
The control of the stator acoustic response can be governed by a number of physical parameter variables. The importance of rigidity within a stator element is well known,
It may be partially affected by new design factors related to the uniqueness of the foam composition.

Although the foam member shown has an open cell structure, a combination of open cell and closed cell structures can also be used. The advantage of the open cell structure is that sound propagates in both directions. In the embodiment of FIG. 18, this bidirectionality is attenuated by attaching a non-porous film 335 to the rear surface of the foam member. The film can be replaced with a reinforcing member made of plastic or other rigid material. A reinforcing member can be attached according to the desired speaker structure.

For example, a conventional electrostatic loudspeaker usually has a planar structure because the diaphragm is not in contact with the stator, but is suspended before the stator. Therefore, if the diaphragm is bent with a curved surface, the gap between the stator and the film is necessarily distorted. However, in the present invention, since the emitter film is in direct contact with the surface of the foam material, a curved surface structure can be formed as easily as a planar structure. In fact,
A curved surface provides the desired resistance to the film and acts as part of the bias function to enhance contact. The ability to mold virtually any shape with foam means that the same degree of tolerance is possible in forming various shapes to match the speaker surface. For example, the speaker may have a curved surface as shown in FIG. 19 to improve sound dispersion. Also, as shown in FIG.
It is also possible to have a circular shape, such as a cylindrical shape and a sphere (not shown). Each of these embodiments has a unique distribution pattern, making it very difficult to incorporate into an electrostatic loudspeaker system, especially for audio output.

In still another embodiment of the present invention, a push-pull operation can be performed as shown in FIG. It includes one foam member 359 and another foam member 360, the latter comprising a front surface 361, an intermediate core portion 362, and a rear surface 363. The front surface of the second foam member (referred to as the "second front surface") is located on the opposite side of the electrostatic foam film 365 from the first foam member. The second front surface has a composition having sufficient rigidity to support the electrostatic film and a conductive property capable of applying a variable voltage sufficient to give a desired ultrasonic signal to the second front surface. is made of. On the surface of the second front surface, there are small depressions as described above, and each depression is created in the surrounding wall structure,
The surrounding wall structure terminates at a contact edge that is substantially the same as the front surface of the foam member. The film sticking means (not shown) for sticking the electrostatic film to the front surface of the second foam member follows the same format as in the above-described single-ended embodiment. As described above, the biasing device is connected to the second foam member that biases the film in direct contact with the second front contact edge so as to directly support the film on the second front surface. A signal source is also applied to the second front with a variable voltage.

The electrostatic emitter film 365 includes a conductive layer in a non-contacting relationship with the first and second foam members, respectively, such that the film, together with the first and second foam members, in a push-pull relationship, has a variable voltage. It must be able to respond capacitively. An insulating member may be required for the second foamed member.

The emitter film can also have several different structures. For example, FIG. 22 shows the first and second foam members 370 and 371 sandwiching a film member. In this case, the electrostatic emitter film consists of at least two sheets of non-conductive emitter film, each including conductive surfaces 374 and 375. The non-conductive emitter film insulates between the conductive layer and the first and second front surfaces, respectively. The conductive surfaces 374 and 375 are joined to form an integral conductive layer.

FIGS. 23 and 24 illustrate a plurality of emitter films 332 and 342 sandwiched between foamed or general support members 330, 331, 340 and 341. . Each additional emitter film will add about 3 dB of power to the emitted ultrasound signal. Infinite numbers of various structures can be adopted in the plurality of combination patterns.

[0096] Yet another embodiment of the present invention relates to a planar magnetic film diaphragm that uses magnetic force to make a parametric transducer, and FIG. 25 illustrates one structure according to the present invention. In particular, this embodiment, compared to the nominal movement of a typical electrostatic diaphragm,
It consists of an ultrasonic emitter with relatively large diaphragm displacement and wide frequency range capability. In fact, the orthogonal displacement (peak to peak movement from the full extension position to the full contraction position of the diaphragm) is as large as 1 to 2 mm. This fact is favorable when compared to the 0.1 to 3 μm range of motion for the rigid transducer emitter surface.

The advantages of the stretching motion of the magnetic diaphragm according to the invention include that the amplitude of the ultrasound output, as well as the sound output for the parametric array, is significantly increased.
The sound output of the present invention can be enhanced using a magnetic field generated by the magnetic core member 426. The core may be a permanent magnet or a composition adjusted for electromagnetic use. Such materials can be either flexible or rigid, depending on the speaker array structure. For example, a planar plate produces a row of sounds with a stunning projection capacity over long distances. A curved emitter diaphragm is formed and supported by a curved support core made of a flexible magnetic material similar to a removable magnet attached to an electric product or the like. With this curved surface structure, the dispersion pattern of the projection sound becomes large, and it becomes possible to feel the directional movement with respect to the emission sound. This can be accomplished by sequentially transmitting sound along emitter elements (or conductive coils) 430 that are linearly arranged along diaphragm 434. If these elements are radiated outward in a distributed structure, the listener perceives that the sound source has physical motion elements along its direction.

Returning to the basic embodiment of FIG. 25, note that a permanent rigid magnetic core or plate 426 is used as a support for the flexible emitter diaphragm 434. The permanent magnet 426 functions as a main means for establishing one magnetic field adjacent to the core member, like the permanent magnet of the acoustic speaker. However, in this case, there are no telescoping cores or dents to receive the stator element, and the core 426 is a flat body and establishes a uniform magnetic field along its length, whereby the diaphragm 4
The necessary balancing force is applied to the variable magnetic field that can be achieved.

The illustrated movable diaphragm 434 extends along the core member 426, displaces slightly away from the core member 426, and within a strong magnetic field, within the intended range of the diaphragm with respect to the core member. Enables orthogonal displacement. Typically, the diaphragm 434 is made of a thin film of Mylar or other strong, lightweight polymer. Many of these materials are
Already used in the electrostatic speaker and ultrasonic emitter industries.

By disposing at least one low-mass, planar structure, and conductive coil (or emitter element 430) on the movable diaphragm, the displacement of the diaphragm 434 can be enhanced. The thin conductive coil 430 generates a magnetic field when current flows. The present inventor has found that placing a voice coil on a flat film can implement the power of a magnetic field, and has the advantage of increasing the displacement of the diaphragm 434 compared to an electrostatic speaker system according to the prior art. This current is supplied to coil 430 by first and second contacts 438 and 442 that are connected to a power source. The first contact 438 is connected to one end of the coil 430, a side common to the normal coil itself. The second contact 442 is located on the opposite side of the coil 430, and is thereby electrically isolated from the first contact 438. In the illustrated embodiment, a second contact 442 extends through the film (or diaphragm 434) and extends along the opposite surface of the film to the pick-up point to interrupt the current circuit. Other methods of electrically isolating the first and second contacts, respectively, will be apparent to those skilled in the art.

As shown in FIG. 26, yet another embodiment of the core member 426 can be a rigid plate 446 having a non-magnetic composition, and the vibrating plate described above is provided on one surface. It includes at least one opposing conductive coil 450 similar in design to the conductive coil 430. Such a coil has first and second contacts 454.
And 458 so that the current passing through the opposing conductive coil 450 can create the required second magnetic field. The at least one opposing conductive coil 4
Positioning the at least one conductive coil 430 on at least one conductive coil 430 by locating the at least one conductive coil 430 on at least one conductive coil 430 on the vibrating movable diaphragm 434 The coils 450 can interact with respective magnetic fields from each coil to cause the diaphragm to emit compression waves.

Again, the first contact 454 is positioned on one side of the diaphragm and the second contact 458 is positioned on the opposite side of the diaphragm. This may take the form of a single coil shown in FIG. 26, or a plurality of conductive coils arranged at equal intervals along the diaphragm shown in FIG. Ideally, it is desirable to place the conductive coils 430 and 450 side by side in multiple rows to maximize the uniformity of the magnetic field as well as the amount of coils used.

FIG. 27 shows another planar magnetic structure of a parametric loudspeaker. Specifically, the speaker comprises a core member 460 serving as a strong support, at least one conductive coil 462 connected to the core, and a diaphragm 468 including a conductive ring 466 responsive to a magnetic field generated by the conductive coil. The principle of operation of this structure is based on the nature of the conductive ring that generates a current through the magnetic field. In particular, when the conductive ring senses a magnetic field gradient, current flows through the ring in a direction that creates a magnetic moment counter force to the magnetic force generated by the coil. This phenomenon causes a repulsion between the coil and the conductive ring. Many physicists say that in the air, 20-30
In a classroom demonstration that launches an aluminum ring to the feet,
We observe the power of this repulsion. The interaction between the coil 462 and the ring 466 is a physics element commonly known as Faraday's law of induction and Lenz's law.
It is partially explained by two principles. See "Basics of Physics," Second Edition, Chapter 34, by Halliday and Resnick.

The present inventor has applied these principles to create a speaker diaphragm that expands and contracts to generate a desired series of compression waves. The neat sequence with conductive rings, resilient, such as Mylar _TM or Kapton _TM, affixed to a flexible film, by superimposing the film onto a corresponding array of conductive coils, the tension that biases the film By repulsing and modulating the amplitude of the current through the coil, it is possible to control the oscillation of the diaphragm. Due to the elasticity of the film, it retracts to a biased rest position, where the film is slightly stressed,
It will be in a stretched state. This biased rest position is created with an alternating base or carrier signal to maintain the lowest level of repulsion between the coil and the ring.

By continuously inputting a variable AC modulated by intelligence, a frequency and an amplitude representing intelligence can be converted into a physical compression wave representing sound. Therefore,
Using a conventional modulated carrier such as a sine wave to provide the desired audio output signal to the described magnetic film emitter, an effective loudspeaker system can be developed.

This system also has a somewhat larger diaphragm displacement compared to the nominal motion of a typical electrostatic diaphragm, and a unique ability to be used as an ultrasonic emitter with a wider frequency range capacity. give. (Micrometer range for ultrasound) It has long been recognized that limited range motion of an electrostatic diaphragm is a major obstacle to high amplitude output generation. However, the magnetically repelling film of embodiments of the present invention provides orthogonal displacement (peak-to-peak movement of the diaphragm from a fully extended position to a biased rest position), which can reach several millimeters. There is also. Thus, the diaphragm displacement of the present invention is highly favorable compared to the relatively small range of motion of the rigid transducer emitter surface and the flexible diaphragm of conventional electrostatic emitters.

Such an enhanced displacement is possible because the effective range of the magnetic field is wider than the short range forces associated with the electrostatic field. Thus, it should be noted that the effective force of the electrostatic emitter extends only in the micrometer range, whereas the magnetic diaphragm of the present invention extends the range by a factor greater than one-hundredth. . Therefore, if a magnetic force is used, it repels or attracts the emitter diaphragm over a very large road.

The advantages of the stretching motion of the large magnetic diaphragm of the present invention include a significant increase in the amplitude of the sonic output for a parametric or acoustic heterodyne array compared to a comparable bimorph transducer system. . Furthermore, the near-linear response is stronger for film emitters than for rigid transducers. These are important factors in the field of parametric loudspeakers becoming more widely available commercially.
Their use has been limited to date.

Another embodiment of the present invention is illustrated in FIG. 28, which shows an electrostatic emitter 510. In particular, the emitter comprises a rigid substrate 511 capable of carrying a voltage, a thin film dielectric material 512 hanging over the substrate, and a conductive layer 513 over the dielectric film 512. Since the dielectric material 12 (such as Mylar) is usually coated directly on top of it with a conductive film 513, the elementary emitter 510 is
Operable with substrate and metal coated mylar film.

As shown in FIG. 29, the preferred embodiment also has an air chamber 51 located below the substrate.
4 and a small passage 530 for allowing air to flow between the chamber and a small recess 516 formed in the upper surface of the substrate.

Referring to both FIGS. 28 and 29, the rigid substrate 511 may generally be formed of materials used in prior art electrostatic emitters. These materials include molded plastic, wood, silicon wafers coated with a conductive surface on the top, and conductive materials that have been easily treated on the top to create unnecessary depressions. FIG. 29 is a cross-sectional view of this structure. It can be seen that the rigid substrate 511 has small conduits 515 that lead from the air chamber 514 to each of the depressions 516 formed on the upper surface of the substrate. The air chamber 514 functions as a common pressure chamber. Since the pressure of the air chamber and each of the depressions 516 communicating therewith is common, the tension of the entire dielectric film 512 becomes more uniform. The air chamber 514 can also be negatively pressured to mechanically bias the thin film 512 against the recessed cup 520, as shown in FIG. By using the bias pressure in this way,
Known problems associated with the use of bias voltages can be avoided.

This recessed cup 520 is the only vibration capable of propagating an ultrasonic carrier signal having sidebands that, in response to the variable signal input 521, causes a heterodyne effect to generate a row of audio sounds 525. Becomes an emitter element. In the present invention, a uniform concave cup, referred to as an emitter element, is provided to independently and carefully tune and tune a uniform valued resonant frequency with little effect from adjacent emitter elements. The depression 516 formed in the substrate 511 is preferably precision molded into a uniform size and structure. Each hollow 51
This is because the uniformity between 6 becomes more precise, and a more finely tuned resonance frequency can be obtained.

The above embodiments of the present invention produce surprising results for a parametric speaker device. The device is arranged such that the recesses each, indirectly, generate an audio output in the emitted ultrasound column. An ultrasonic heterodyne effect occurs in each of these columns emitted from the tuned emitter element, which actually enhances the sound pressure level (SPL) at some distance from the emitter 510. As shown in FIG. 29, each emitter section 520 propagates a row of sounds 525 with very high directivity. By providing an array of many emitting sectors 520 that are uniformly tuned to a desired resonant frequency, the amplitude of the amplitude is greater than a single film electrostatic diaphragm that works with a single voltage source. Simulate a uniform wavefront. The use of uniform indentations is advantageous over the prior art because it is duplicated and therefore predictable in manufacturing. The prior art required quality control, including careful inspection of each emitter substrate, to ensure that operable surfaces of pit holes and depressions were formed. Since mechanical and chemical etching methods produce various results due to differences in environment, materials used, and process volatility, quality control was indispensable. On the other hand, the embodiment according to the present invention can be implemented by a conventional molding method or machining method.

Another embodiment of the ultrasonic electrostatic transducer is shown in FIG. A cross-sectional view of the hemispherical electrostatic converter 551 is shown as being fixed to the base 552. A hemisphere is created by two cylindrical wavy stators 556, with a non-planar diaphragm 560 disposed between the two opposing stators. In addition, a support structure 553 runs inside the hemisphere or along the long axis of the hemisphere. It should be understood that these stators have holes and apertures, are acoustically permeable, and can pass ultrasonic waves. The diaphragm is biased by a bias voltage 550 and adds an audio signal 554 to generate an ultrasonic compression wave. A buffer or insulating layer 558 is included within the stator to prevent the diaphragm from directly touching the conductive layers of the stator,
In addition, the contact with the stator is prevented from being distorted.

FIG. 31 is a perspective view of a hemispherical electrostatic speaker. Due to the hemispherical nature of the present embodiment, the sound emitted through 556 is radiated 180 degrees in multi-axes. FIG. 32 shows a global embodiment of the present invention. This figure is a partially broken view of the spherical embodiment 580 combining the two hemispheres shown in FIG. With this spherical structure, ultrasonic waves 590 are generated in all possible directions. The electrical assembly 584 (as shown in the destruction view) can be the base of the two hemispheres. The electrical assembly can also be of a small size contained within a hemisphere. Via input 588, the diaphragm contained within the hemisphere is biased, and then through 586, an audio signal is sent.

It is clear that various modifications and combinations may be developed by those skilled in the art based on the above-described embodiments of the present invention. Accordingly, the invention is to be defined by the following claims, and is not limited to the above examples.

[Brief description of the drawings]

FIG. 1a is a diagram illustrating a prior art parametric speaker using a plurality of bimorph piezoelectric transducers. FIG. 1b is a diagram representing another embodiment of a parametric speaker using a plurality of bimorph piezoelectric transducers. FIG. 1c is a diagram of a bimorph transducer that drives air at a small point in space and creates an impact. FIG. 1d is an illustration of a film converter of the present invention driving air in a uniform manner to distribute drives and reduce shock. FIG. 1e is a waveform diagram of the primary frequency below the impact level and the primary frequency of the impact level.

FIG. 2 is a representative example of a back plate with a circular V-groove for a large electrostatic film converter. FIG. 2a is a cross-sectional view of the electrostatic back plate and the diaphragm of FIG. 2 taken along line 2a-2a. FIG. 2b is a diagram of an electrostatic converter with an arc-shaped back plate and a diaphragm.

FIG. 3 is a diagram of a rectified sine waveform of a piezoelectric film. FIG. 3a is a diagram of a rectified sinusoidal waveform of a piezoelectric film spaced by a quarter wavelength. FIG. 3b is a diagram of a shallow rectified sinusoidal waveform of a piezoelectric film. FIG. 3c is a diagram of a shallow rectified sinusoidal waveform of a backed piezoelectric film.

FIG. 4 is a diagram of a piezoelectric film having a sine wave shape. FIG. 4a is a diagram of a sinusoidal piezoelectric film with a back plate. FIG. 4b is a diagram of a sinusoidal piezoelectric film with a back plate and a curved open directional angle of primary frequency. FIG. 4c is a diagram of a sinusoidal piezoelectric film used in a bipolar primary frequency / bipolar secondary frequency mode.

FIG. 5 is a diagram of a backed piezoelectric film used in either a concave or convex hollow shape. FIG. 5a is a diagram of a piezoelectric film used in a concave convex surface. FIG. 5b is a diagram of a piezoelectric film used with a concave concave surface.

FIG. 6 is a diagram illustrating a prior art parametric speaker using a plurality of bimorph piezoelectric transducers as an ultrasonic emission source.

FIG. 7 illustrates another prior art parametric loudspeaker embodiment using multiple bimorph piezoelectric transducers and representing various imperfections in speaker performance.

FIG. 8 is a perspective view of an emitter drum converter made in accordance with the principles of the present invention.

FIG. 9 is a top view showing a plurality of openings in the emitter surface of the emitter drum converter.

FIG. 10 is a cut-away side view of the emitter drum converter and the emitter surface, showing the film disposed over the aperture in the emitter surface.

11A and 11B are enlarged side views of a film that vibrates while extending over a plurality of openings in an emitter surface.

FIG. 12 is a graph showing an example of displacement versus frequency of a film (piezoelectric film) according to a preferred embodiment. This graph shows the resonance frequency and the typical bandwidth generated.

FIG. 13 is a cut-away side view of another embodiment of an emitter drum converter where the emitter drum converter is pressurized.

FIG. 14 is a more specific embodiment of the present invention for transmitting an acoustically heterodyne ultrasound fundamental frequency and an ultrasound information carrier frequency to generate a new acoustic or subsonic frequency.

FIG. 15 is another embodiment showing a cutaway side view of the sensor drum transducer and the sensor surface showing the sensing film disposed over the opening in the sensor surface.

FIG. 16 is a perspective view of a transducer having a preformed concave elliptical diaphragm.

FIG. 17 is a cross-sectional view of FIG. 16 showing a transducer with a preformed film that vibrates to generate ultrasonic waves.

FIG. 18 shows a side sectional view of a single-ended electrostatic speaker.

FIG. 19 shows an arc shape representing a curved surface configuration of the present speaker device.

FIG. 20 shows a cylindrical shape representing a possible configuration of the speaker device.

FIG. 21 is a schematic diagram of a basic form of an embodiment of a foam stator speaker of a speaker device in a push-pull configuration.

FIG. 22 illustrates an embodiment of a speaker device in which a film is sandwiched between opposing foam stators.

FIG. 23 shows an embodiment of a plurality of films of the speaker device.

FIG. 24 shows an embodiment of a plurality of films of the speaker device.

FIG. 25 is a top perspective view showing a thin film diaphragm having a plurality of magnetic coils disposed on an emitter diaphragm and suspended above a magnetic core element.

FIG. 26 is an exploded view of another embodiment showing the emitter diaphragm and the magnetic coil facing above the core.

FIG. 27 is a cut-away perspective view showing a thin film diaphragm having a plurality of rings disposed on an emitter diaphragm and suspended above a core element.

FIG. 28 is a standing perspective view of the electrostatically-tuned electrostatic emitter.

FIG. 29 is a cross-sectional view of the emitter of FIG. 28.

FIG. 30 is a side sectional view of a hemispherical electrostatic speaker.

FIG. 31 is a perspective view of a hemispherical electrostatic speaker.

FIG. 32 is a side perspective view of a spherical electrostatic speaker.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS , JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Norris, Elwood G. California, United States of America 13824 (72) Inventor Croft, James Jay Sard, California United States 92064, Poway, Quiet Hills Drive 13633 F-term (reference) 5D004 BB01 CC07 CC09 CC10 5D016 AA01 BA01 BA05 DA00 EC01 EC21 EC22 5D019 FF01 5D020 AC11 5D021 CC02

Claims (116)

[Claims] 1. A method for generating a parametric audio output based on the interaction of a plurality of ultrasonic frequencies in air as a non-linear medium, the method comprising: a) having a value difference corresponding to an audio frequency range. Generating an electronic signal comprising at least two ultrasonic signals; b) transmitting the electronic signal to an electroacoustic film transducer diaphragm that couples directly to air as part of a one-stage energy conversion process; c). Converting the electronic signal at the diaphragm directly into mechanical displacement as a driving member of a parametric loudspeaker; d) interacting at least two ultrasonic signals from the diaphragm in air to generate parametric audio. Mechanically emitting into the air as an ultrasonic compression wave that produces an output. 2. The method of claim 1, wherein step b) includes the further step of transmitting an electronic signal to an electrostatic film transducer. 3. The method of claim 1, wherein said step b) includes transmitting said electronic signal to a piezoelectric film diaphragm as an electroacoustic transducer diaphragm. 4. The method of claim 1, wherein step b) includes transmitting the electronic signal to an electro-thermo-mechanical film diaphragm as an electro-acoustic transducer diaphragm. 5. The method of claim 1, wherein step b) includes transmitting to a flat magnetic film as an electroacoustic transducer diaphragm. 6. The method of claim 2, wherein said step b) includes transmitting an electronic signal to an electrostatic rear plate having a surface configuration including a circular V-groove operable as a stator member with respect to said diaphragm. The described method. 7. The method of claim 3, wherein step b) includes transmitting an electronic signal to a piezoelectric film diaphragm having a rectified sinusoidal waveform. 8. The method of claim 7, wherein said step b) comprises the further step of transmitting an electronic signal to a piezoelectric film diaphragm supported by a back plate having the form of a rectified sinusoidal waveform. 9. The method of claim 3, wherein step b) includes transmitting an electronic signal to a piezoelectric film diaphragm having a sinusoidal waveform. 10. The method according to claim 9, wherein step b) comprises the further step of transmitting an electronic signal to a piezoelectric film diaphragm supported by a back plate having the form of a sinusoidal waveform. 11. The method of claim 1, further comprising selecting a transducer diaphragm having a magnitude greater than the wavelength of the ultrasonic frequency at the wavelength value of the lowest frequency.
The described method. 12. The method of claim 1, further comprising the step of selecting a transducer diaphragm having a magnitude greater than ten times the wavelength of the ultrasonic frequency at the lowest value. 13. The method of claim 3, further comprising selecting a transducer diaphragm having a convex curvature that produces a diffuse radiation pattern for emission of a parametric output. 14. The method of claim 3, further comprising selecting a transducer having a concave curvature that produces a focused radiation pattern for emission of the parametric output.
The described method. 15. The method of claim 3, further comprising the step of selecting a transducer diaphragm having a dipole propagation mode that produces a diffuse radiation pattern for emission of a parametric output. 16. The method of claim 3, further comprising the step of spacing the transducer diaphragm from the supporting back plate a distance of a quarter wavelength of the selected frequency. 17. The method of claim 16, further comprising compensating means for electronically driving the film peak out of phase using the film grooves. 18. A recess comprising a monolithic sheet with closely spaced recesses in a closely spaced parallel array that produces a substantially uniform and uniform radiation pattern for emission of parametric output across the surface of the diaphragm. 4. The method of claim 3, further comprising the step of providing an attached transducer diaphragm. 19. A loudspeaker device for producing a parametric audio output based on the interaction of a plurality of ultrasonic frequencies in air as a non-linear medium, comprising: a) an ultrasonic signal source; an audio signal source; A modulation coupled to an ultrasound signal source and an audio signal source to mix the ultrasound signal and the audio signal to result in an electronic signal comprising at least two ultrasound signals having a value difference within an audio frequency range. B) an electroacoustic film transducer diaphragm coupled to the parametric signal generation system that couples directly to air as part of a one-stage energy conversion process; c) driving a parametric speaker. A diaphragm is arranged as a member to enable mechanical displacement of the diaphragm. And a supporting structure that stabilizes the speaker. 20. The method of claim 19, wherein said transducer comprises an electrostatic transducer. 21. The method of claim 19, wherein said transducer comprises a piezoelectric film diaphragm as the electroacoustic transducer diaphragm. 22. The method of claim 19, wherein said transducer comprises an electro-thermo-mechanical film diaphragm as the electro-acoustic transducer diaphragm. 23. The method of claim 19, wherein said transducer comprises a magnetic film diaphragm as the electroacoustic transducer diaphragm. 24. A method for enhancing a parametric output based on the interaction of a plurality of ultrasonic frequencies in air as a non-linear medium, the method comprising: a) at least two values having a value difference within an audio frequency range. Generating an electronic signal including two ultrasonic signals; b) transmitting the electronic signal to an emitter film transducer diaphragm having an array of arcuate emitter portions formed in the emitter film; Electromechanically displacing said array of arcuate emitters in phase as a driving member; and d) transmitting at least two ultrasonic signals from said diaphragm into air and into said air to produce said parametric output. Emitting as an interacting ultrasonic compression wave. 25. The method of claim 25, wherein said step c) includes displacing said emitter sections in a controlled manner to minimize saturation of ambient air at each arcuate emitter section as part of a parametric speaker distortion reduction. The method according to claim 24, comprising the step of: 26. The method of claim 24, wherein step d) comprises the further step of emitting an ultrasonic frequency from the emitter section in a collimated form. 27. The method according to claim 24, wherein step b) includes transmitting a further electronic signal to the piezoelectric film diaphragm. 28. The method according to claim 27, wherein step b) includes transmitting an electronic signal to a piezoelectric film diaphragm having an array of circular arcuate emitters. 29. The method of claim 27, wherein step b) includes transmitting an electronic signal to a piezoelectric film diaphragm having an array of elongated arcuate emitters. 30. The step b) further comprising the step of transmitting an electronic signal to a piezoelectric film diaphragm having an array of elongated channel-like depressions arranged in a substantially parallel relationship. The described method. 31. The method of claim 27, wherein step b) includes transmitting an electronic signal to a piezoelectric film diaphragm having a rectified sinusoidal shape.
The described method. 32. The method of claim 27, wherein step b) includes transmitting an electronic signal to a piezoelectric film diaphragm supported by a back plate having a substantially flat configuration. 33. The step b) further comprises the step of transmitting an electronic signal to a piezoelectric film diaphragm having a substantially flat configuration, except for an arcuate emitter portion extending slightly from the flat configuration. 28. The method of claim 27, comprising: 34. The method of claim 24, further comprising selecting a transducer diaphragm having a magnitude greater than a wavelength of the ultrasonic frequency at the lowest value. 35. The method of claim 24, further comprising selecting a transducer diaphragm having a magnitude greater than ten times the wavelength of the ultrasonic frequency at the lowest value. 36. The method of claim 24, further comprising selecting a transducer diaphragm having a generally convex curvature that produces a diffuse radiation pattern for emission of a parametric output. 37. The method of claim 24, further comprising selecting a transducer diaphragm having a generally concave curvature to produce a focused radiation pattern for emission of a parametric output. 38. The method of claim 31, further comprising the step of: associating a rate of attenuation of the ultrasonic emission resulting from absorption of the ultrasonic energy in air based on the value of the frequency with a radius for the concave curvature of the diaphragm, wherein the radius is 4. The method of claim 3, wherein the acoustic emission is selected to focus at least on the focused ultrasonic beam, thereby at least compensating for the ultrasonic energy loss.
7. The method according to 7. 39. The method of claim 24, further comprising the step of spacing the transducer diaphragm from the supporting rear plate by a distance of a quarter wavelength of the selected frequency. 40. The selected frequency is a carrier frequency.
The described method. 41. A recessed transducer comprising a monolithic film sheet having closely spaced recesses in a closely spaced parallel array that produces a substantially uniform and uniform line pattern for emission of parametric output across the surface of the diaphragm. 28. The method of claim 27, further comprising providing a diaphragm. 42. The method according to claim 42, wherein the step b) includes a step including an opening aligned with the arc-shaped emitter section, and having a sufficient depth to allow free oscillation of the arc-shaped emitter section of the diaphragm. 28. The method of claim 27, further comprising the step of transmitting an electronic signal. 43. A method for enhancing a parametric output based on the interaction of a plurality of ultrasonic frequencies in air as a non-linear medium, the method comprising: a) at least two values having a value difference within an audio frequency range. Generating an electronic signal comprising two ultrasonic signals; b) simultaneously transmitting the electronic signal to an array of arcuate emitters formed in a common electroacoustic film transducer diaphragm; c) for a parametric speaker. Displacing the emitters in a controlled manner to minimize saturation of ambient air at each of the arcuate emitters as part of the distortion reduction; and d) displacing the arcuate emitters as a driving member of a parametric speaker. Electromechanically displacing the array in phase; e) reducing the number of ultrasonic compression waves; Method comprising the steps of releasing into the air Kutomo two of said ultrasound signal from the diaphragm, the method comprising interacting the ultrasonic compression wave in the air to yield f) parametric output, a. 44. The step c) limiting the electronic signal based on a weighted relationship between the sound pressure level of the emitter section, the ultrasonic frequency and the magnitude, wherein the maximum electronic signal is limited to each arc. 44. The method of claim 43, further comprising the step of preventing continuous distortion of the audio output by minimizing ambient air saturation at the emitter section. 45. The method of claim 44, wherein step c) includes a more specific step of limiting the sound pressure level for all emitter sections to less than 140 dB. 46. A loudspeaker device for producing a parametric output based on the interaction of a plurality of ultrasonic frequencies in air as a non-linear medium, comprising: a) at least two speakers having a value difference within an audio frequency range. An ultrasonic signal source, an audio signal source, and a modulator coupled to the ultrasonic and audio signal sources for mixing the ultrasonic and audio signals to result in an electronic signal comprising two ultrasonic signals B) an electroacoustic film transducer diaphragm having an array of arcuate emitters coupled to the parametric signal generation system; and c) a drive member for a parametric speaker coupled to the diaphragm. As an arc-shaped emitter to allow mechanical displacement in phase of the arc-shaped emitter section. A speaker device comprising: an arc-shaped emitter array for arranging and stabilizing a mitter unit; and a support structure in which a cavity is aligned. 47. The apparatus of claim 46, wherein the arcuate emitter section array is aligned and supported to propagate a collimated beam of ultrasonic radiation for enhanced generation of a parametric output. 48. The apparatus of claim 46, wherein said transducer comprises a piezoelectric film diaphragm as the electroacoustic transducer diaphragm. 49. The apparatus of claim 46, wherein said arcuate emitter has a circular configuration. 50. The apparatus of claim 49, wherein said piezoelectric film diaphragm includes an isotropic characteristic that produces a uniform electromechanical response across said arcuate emitter. 51. The apparatus of claim 46, wherein said arcuate emitter has an elongated configuration with a long axis. 52. The apparatus of claim 51, wherein the piezoelectric film diaphragm includes an anisotropic characteristic that produces a large electromechanical response perpendicular to the long axis of the arcuate emitter. 53. The apparatus according to claim 51, further comprising a compartment coupled to the emitter section, the compartment maintained at a desired pressure different from an ambient pressure and having sufficient strength to displace the diaphragm to a curvature as the emitter section. The described device. 54. The apparatus of claim 53, wherein the desired pressure is at a negative pressure level relative to ambient pressure to draw the diaphragm into the aligned cavity. 55. The apparatus of claim 53, further comprising means coupled to the compartment to cause permanent scaling of the compartment with the desired pressure. 56. A method for enhancing a parametric output based on the interaction of a plurality of ultrasound frequencies in air as a non-linear medium, comprising: a) combining an ultrasound carrier signal and at least one other ultrasound signal. Generating an electronic signal including at least two ultrasonic signals having a difference in value with respect to a carrier signal falling within an acoustic frequency range; and b) in a common electroacoustic film transducer diaphragm having a main propagation axis. Transmitting an electronic signal to an array of arcuate emitters formed in the array; and c) providing a focus of an ultrasonic beam emitted from at least an outer periphery of the array at a predetermined focus angle with respect to the main propagation axis. Constructing said array of emitter portions in a generally concave configuration for d. Electromechanically displacing said array of emitter portions in phase; e) emitting at least two of said ultrasonic signals from the diaphragm into the air as ultrasonic compression waves; f) producing a parametric output. Interacting an ultrasonic compression wave in air with the method. 57. The method of claim 56, wherein said step of configuring said array comprises selecting a focusing angle based on a need to compensate for energy loss due to ultrasound energy absorbed into the air. 58. The step of configuring the array comprises selecting a focusing angle at which the ultrasonic energy is applied along a primary propagation axis substantially coincident with an energy loss resulting from absorption of the ultrasonic energy by air. 57. The method of claim 56, comprising: 59. The step of constructing the array calculates ultrasound energy loss due to absorption based on selecting a focusing angle to approximately match the calculated energy loss in a selected spatial domain. 59. The method of claim 58, comprising the further step. 60. The method of claim 58, further comprising the step of selecting a convergence angle within a range of 0.1 to 5 degrees with respect to said main propagation axis. 61. The method of claim 58, further comprising the step of selecting a convergence angle of about 3 degrees with respect to said main propagation axis. 62. A transducer and loudspeaker arrangement for emitting parametric or ultrasonic compression waves into ambient air to produce an audio or subsonic output, comprising: a side wall surface and first and second opposed ends. A substantially hollow drum having an end that defines an outer surface facing the first end of the drum and oriented in a direction remote from the drum; and an inner surface disposed toward an interior cavity of the drum. A solid emitter plate having a plurality of openings extending between the outer surface and the inner surface; a thin piezoelectric film disposed across the openings in the emitter plate; and An electrical contact for providing an applied electrical input; an arc coupled to the drum and extensible in response to a change in the applied electrical input at the piezoelectric film. For expanding the film to the emitter forms, causing the biasing pressure with respect to a thin film in the opening, the device comprising a pressure means for producing a compression wave in the surrounding environment. 63. The method of claim 62, further comprising a round opening extending through the emitter plate, wherein the pressure means is operable to expand a thin film in the opening in an arcuate emitter configuration. apparatus. 64. A vacuum means in the internal cavity for creating a negative pressure in the thin film such that the pressure means draws the thin film into an arcuate emitter configuration toward the internal cavity of the drum. Claim 6.
3. The device according to 3. 65. The support means includes a mask plate having an opening aligned with the opening of the emitter plate, the film being sandwiched between the emitter plate and the mask plate. Item 64. The apparatus according to Item 64. 66. The apparatus of claim 62, wherein said pressure means includes means for creating a positive pressure on said thin film to push said thin film away from said emitter plate into said arcuate emitter configuration. 67. A bottom plate coupled to the second end of the drum and sealing the internal cavity of the drum to enable a pressure differential between the interior of the drum and the surrounding environment to occur. 64. The apparatus of claim 63, further comprising scaling means. 68. The electrical contact means includes a conductive peripheral ring disposed above and in electrical contact with the periphery of the thin film, the ring providing a supply for applied electrical input. 63. The device of claim 62, wherein the device is coupled to a source. 69. The apparatus of claim 63, wherein said thin film comprises a vinylidene difluoride resin material. 70. The apparatus of claim 62, wherein the emitter plate comprises a disk having at least ten closely spaced openings in a generally central region. 71. The apparatus of claim 68, wherein said openings are arranged in a honeycomb pattern for maximum density. 72. The apparatus of claim 6, further comprising a sound absorbing material disposed within an interior cavity of the drum to reduce the impact of reverse waves received within the disk.
7. The apparatus according to 6. 73. The apparatus of claim 62, further comprising the step of separating the transducer film from the supporting back plate by a distance of a quarter wavelength of the selected frequency. 74. The selected frequency is a carrier frequency.
The described device. 75. An ultrasonic frequency generator for supplying an ultrasonic signal to the piezoelectric film, an acoustic frequency generator for supplying an audio signal to be modulated into an ultrasonic signal, the ultrasonic frequency generator and the sound wave A modulating means coupled to the frequency generating means to produce an ultrasonic carrier wave with the modulated sound wave; and a modulating means coupled to the modulating means to the piezoelectric film to simulate the generation of a corresponding compression wave at the emitter plate. 63. The apparatus of claim 62, further comprising: transmission means for providing the carrier wave and the modulated acoustic wave. 76. The apparatus according to claim 71, wherein said modulating means comprises an amplitude modulator. 77. A system for indirectly generating at least one new acoustic or subsonic frequency from at least two ultrasonic frequencies of different values, the system comprising a first end, a second end, and a middle end. A substantially hollow drum having a sidewall surface; and an emitter plate coupled to the first end of the drum and having an outer surface and an inner surface, the emitter plate including a plurality of openings extending from the inner surface to the outer surface. A rear cover coupled to the second end of the drum and arranged to seal a second end of the hollow drum; and a rear cover mounted on the emitter plate above the plurality of openings. An electrically responsive diaphragm film disposed on the emitter plate and the diaphragm film, wherein the diaphragm film at the aperture is subjected to compression waves within an ultrasonic frequency range in response to an applied electrical input. Arising Pressure means extending to an arcuate emitter configuration that is capable of being coupled to said barrier film, wherein said plurality of apertures and associated arcuate emitter configuration comprises: (i) a first ultrasonic wave; and (ii) said first ultrasonic wave. The ultrasonic response acting as an ultrasonic frequency emitter so as to simultaneously propagate the ultrasonic frequency of the second and the second ultrasonic frequency that propagates the difference frequency within the acoustic bandwidth by interacting in the compressible transmission medium. And a resulting electrical input means. 78. An electrical input means including a modulating means coupled to said barrier film, such that said input ultrasonic frequency and said modulated ultrasonic wave frequency output produce first and second ultrasonic frequencies. Providing an electronic signal, wherein said first and second
78. The system of claim 77, wherein the ultrasonic frequencies of the plurality have a difference equal to at least one new acoustic or subsonic frequency. 79. An emitter for producing audio output into the air from ultrasonic radiation, the emitter being disposed over a surface of the barrier film, and being ultrasonically responsive to an electronic signal corresponding to an ultrasonic frequency. An emitter having a plurality of arcuate emitter configurations configured to generate waves into the air. 80. The emitter of claim 79, further comprising a support plate coupled to said barrier film for supporting said barrier film in said arcuate emitter configuration and emitting ultrasonic compression waves into air. 81. The support plate allows the arcuate emitter configuration to contract to change the curvature of the barrier film over the aperture in response to an applied voltage.
80. The emitter of claim 79, including an aperture aligned with the emitter configuration. 82. The emitter of claim 80, wherein the support plate and the barrier film are configured to create a uniform wavefront of the ultrasonic compression wave. 83. The emitter of claim 82, wherein the arcuate features of said barrier film are matched to emit compression waves from said barrier film along a parallel axis. 84. The emitter of claim 81, wherein said openings are of a common size that is matched to the emitter configuration of the barrier film supported on the support plate. 85. The piezoelectric diaphragm includes electrical contacts for receiving one signal applied to all of the emitter forms of the diaphragm, thereby reducing harmonic and phase distortion in the ultrasonic emission. 80. The emitter of claim 79, wherein said emitter is minimized. 86. The emitter of claim 79, wherein the emitter configuration of the barrier film is uniform in size, curvature, and composition. 87. The emitter of claim 79, wherein said emitter configuration is disposed over a surface of said barrier film in a honeycomb configuration. 88. The emitter of claim 80, wherein said aperture allows movement of said barrier film. 89. The emitter of claim 79, wherein said piezoelectric barrier film is made from a vinylidene difluoride resin composition having isotropic properties. 90. The emitter of claim 79, wherein said piezoelectric barrier film is made from a composition having anisotropic properties. 91. A parametric loudspeaker comprising a support plate and a piezoelectric thin film having an array of ultrasonic emitters for emitting ultrasonic compression waves to a non-linear air medium. 92. The parametric loudspeaker of claim 91, wherein said ultrasonic emitter array comprises an array of arcuate emitter cells disposed across said piezoelectric film. 93. The parametric speaker according to claim 92, wherein the piezoelectric film includes a vinylidene difluoride resin. 94. A parametric loudspeaker, comprising: an electrostatic emitter film that emits an ultrasonic signal including a desired sound signal that is modulated into an ultrasonic signal in response to an applied variable voltage; A first foam member having a portion and a rear surface, wherein at least the front surface has a hardness sufficient to support the electrostatic film;
And a surface comprising a small cavity having a peripheral wall structure defining each cavity, said surface comprising a composition including conductive properties that allow a variable voltage to be applied to said front surface to provide a desired audio signal. A film application means for applying the electrostatic film to the front surface of the foam member, wherein the film is formed on the front surface of the foam member. Biasing means for biasing the film into direct contact with the contact edge of the front surface so as to be directly supported by the signal source; a signal source for supplying an ultrasonic signal including a sound signal to the emitter film; Coupling means for coupling the signal source to a loudspeaker device to supply a variable voltage comprising: a parametric loudspeaker. 95. A second foam member having a front surface, an intermediate portion, and a rear surface, wherein the front surface (referred to as a second front surface) of the second foam member is separated from the first foam member. The second front surface is located opposite the electrostatic emitter film, the second front surface having sufficient hardness to support the front electrostatic film, and capable of applying a variable voltage to the second front surface; Wherein the second front surface includes a surface including a small cavity having a peripheral wall structure defining each cavity, and the wall structure surrounding the front surface includes the foaming member. Ending at a contact edge substantially coincident with the front surface of the member, comprising film application means for applying an electrostatic film to the front surface of the second foam member, wherein the biasing means is coupled to the second foam member. The film is the second front surface Biasing the film in direct contact with the contact edge of the second front surface so as to be more directly supported, wherein the coupling means directs the signal source to a second voltage having a variable voltage including the acoustic signal; Means for coupling to the front surface of the device, wherein the electrostatic emitter film is capacitively responsive to the first and second front surfaces to a variable voltage in a push-pull relationship. 95. The apparatus of claim 94, further comprising a conductive layer in non-contact with the first and second foam members. 96. The apparatus further comprises a second foam member having a front surface, an intermediate portion, and a rear surface, wherein the front surface (referred to as a second front surface) of the second foam member is separated from the first foam member. Wherein the second foamed member has a hardness sufficient to support the electrostatic film,
And a surface comprising a small cavity having a peripheral wall structure defining each cavity, wherein the second front surface comprises a composition including conductive properties that enable the application of a variable voltage to provide a desired acoustic signal. And a film application means for applying an electrostatic film to the front surface of the second foam member, wherein the peripheral wall structure terminates at a contact edge substantially coincident with the front surface of the foam member. Means are coupled to the second foam member so that the film is
Biasing the film in direct contact with a contact edge of the second front surface so as to be directly supported by the front surface of the second foam member having a variable voltage including a sound signal. 95. The apparatus of claim 94, further comprising means for coupling a signal source thereto. 97. The first and second electrostatic emitter films to allow the film to respond capacitively with the first and second front surfaces to the variable voltage in a push-pull relationship. 97. The apparatus of claim 96, further comprising a conductive layer biased in contact with each of the two foam members. 98. An emitter device for producing a parametric output based on the interaction of a plurality of ultrasonic frequencies to produce an acoustic or subsonic signal in air as a non-linear medium, wherein the emitter device is adjacent to the core member. A core member having means for securing a first magnetic field; extending along the core member and perpendicular to an intended area of the diaphragm within the strong portion of the first magnetic field with respect to the core member; A movable film diaphragm displaced by a short separation distance from a core member to allow displacement, and at least one small mass flat conducting coil mounted on the movable diaphragm, wherein current is applied to both ends of the coil. A conductive coil including first and second contacts to allow the flow of a current, and a variable series of current supplied to at least one said coil to be adjusted to include an ultrasonic frequency range. To produce Chijimiha, the first magnetic field and variably interact with desired and means to produce a second magnetic field for sucking reject the diaphragm at the frequency. 99. The apparatus of claim 98, wherein the permanent magnet comprises a rigid magnetic plate having a size slightly greater than the size of the active emission surface of the emitter device. 100. The core member includes a rigid plate formed of a non-magnetic composition, one side of the plate having first and second contacts to allow current flow to opposing conducting coils. 100. The apparatus of claim 98, comprising at least one opposed conducting coil having 101. The at least one opposing conducting coil is juxtaposed to the at least one conducting coil on the movable diaphragm to produce a compression wave with the at least one conducting coil and at least one of the at least one conducting coil. 110. The apparatus of claim 100, wherein the opposing conducting coils are located at a location of a rigid plate that allows each to generate a respective magnetic field from each. 102. The apparatus of claim 98, wherein said diaphragm comprises a thin film and at least one said coil is mounted on one side of said film. 103. The apparatus of claim 102, wherein said film comprises a polymer having isotropic properties on its surface, resulting in a uniform response to applied tension. 104. The at least one conductive coil includes a plurality of voice coils, each voice coil includes a support periphery in contact with the diaphragm, and substantially displaces the diaphragm in each coil from an adjacent coil. 100. The apparatus of claim 98, wherein the apparatus provides means for isolating the device. 105. The support perimeter isolating the coil includes a grid configuration defining a plurality of open displacement cavities on a surface of a core member adjacent the diaphragm, each cavity aligned with one of the conductive coils. 105. The apparatus of claim 104, wherein 106. The means for providing the first magnetic field has a variable current to at least one coil of the core member in anti-phase relationship with a variable current applied to produce the second magnetic field. 106. The apparatus of claim 105, wherein the apparatus enhances suction rejection of the diaphragm to produce a series of compression waves tuned to include an ultrasonic frequency range. 107. Produce a parametric output based on the interaction of multiple ultrasonic frequencies to produce an acoustic or subsonic signal in air as a non-linear medium, but with a typical electrostatic diaphragm motion. A method having a relatively large diaphragm displacement capability as compared to a relatively small motion, comprising: (a) providing a first magnetic field adjacent a support core; and (b) at least one A conducting coil extends along the core member within a strong portion of the first magnetic field a short separation distance from the core member to allow an intended orthogonal displacement range of the movable diaphragm with respect to the core member. Attaching to a movable diaphragm that is displaced by: (c) to produce a series of compression waves that are adjusted to include an ultrasonic frequency range;
Supplying a variable current to at least one coil to produce a second magnetic field variably interacting with the first magnetic field to attract and reject the diaphragm at a desired frequency. 108. A method for generating a parametric output based on the interaction of a plurality of ultrasonic frequencies to produce an acoustic or subsonic signal in air as a non-linear medium, but comparing to typical electrostatic diaphragm motion. An ultrasonic emitter device having a displacement of a relatively large diaphragm and having a capacitance in a wide frequency range, comprising: a core member having means for securing a variable magnetic field adjacent to the core member; A movable diaphragm disposed in a tensioned position and displaced a short separation distance from the core member to allow for an intended range of orthogonal displacements within the strong portion of the variable magnetic field with respect to the core member; In a direction to produce opposing opposing magnetic forces rejected by the variable magnetic field of the core member at the desired frequency for the generation of a series of compression waves tuned to include the ultrasonic frequency range. At least one conductive ring mounted on the movable diaphragm to allow current flow. 109. The apparatus of claim 108, wherein said core member comprises an electromagnet. 110. The rigid plate includes a flat plate having a uniform variable magnetic field along a plate surface closest to the movable diaphragm.
The described device. 111. The core member includes a rigid plate formed of a non-magnetic material, at least one side of the plate having first and second contacts to allow current flow in the conducting coil. 111. The device of claim 108, comprising one opposed conducting coil. 112. At least one said conducting coil is mounted at a location of said rigid plate juxtaposed with at least one conductive ring on said movable diaphragm, wherein at least one said conducting coil and at least one said 112. The apparatus of claim 111, wherein the apparatus allows for generating an opposing magnetic field that interacts with an opposing conductive ring to generate the compression wave. 113. The apparatus of claim 108, wherein said diaphragm comprises a thin film and at least one said ring rests on one side of said thin film. 114. The apparatus of claim 111, wherein the thin film comprises a polymer having isotropic elastic properties on its surface that produces a uniform response to applied tension. 115. An ultrasonic emitter device for converting an electronic signal into an audio output by an acoustic heterodyne effect of ultrasonic emission, having a top surface including a row of cavities of a predetermined size, and within an ultrasonic frequency range. A stiff core member including means for enhancing at least one resonance frequency operable as a carrier frequency of the core member; a means for generating an electrostatic field on a top surface of the core member; It is arranged in tension over the cavity and has resilience to allow the intended range of the emission sector of the diaphragm, i.e., a right angle displacement, which is arranged in a strong magnetic field above the cavity of the core member. A dielectric diaphragm; a conductive medium applied to one surface of the diaphragm and electrically insulated from the core member; and an electric field of the core member coupled to the conductive medium. Within a desired ultrasonic frequency, which allows a variable interacting electric field to be applied to the diaphragm, propagating a series of said ultrasonic compression waves that are demodulated into a non-linear air medium to produce an audio output. A modulating means for producing a series of ultrasonic compression waves emerging from the emission sector of the diaphragm. 116. The apparatus of claim 115, wherein the core member includes a row of cavities having a uniform concave configuration substantially tuned to a common resonance frequency.