US3668335A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic loudspeaker
Assignee: ALEXANDER MICHAEL T
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Filing: 1969-06-17
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Granted: 1972-06-06
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Expires: 1989-06-17
Abstract
Abstract An electrostatic loud speaker system is shown which combines a balanced transducer, an amplifier and an enclosure each of unique construction which together permit the reproduction of frequencies over the full audio range. The electrostatic transducer is shown surrounded by an enclosure that has an outlet passage preferably significantly smaller than the transducer and an acoustic lens preferably guides the sound through the narrow outlet into a wave form of circular cross-section. By these provisions a low resonant frequency for the speaker and wide dispersal of the directional high frequencies are achieved in an enclosure of limited size. The fixed electrodes of the transducer are of substantial thickness and are formed of high dielectric constant material, achieved preferably by molding a lower K matrix with additives raising K and lowering volumetric resistivity. The amplifier is formed of series-connected active devices, one controlled by the other. A third active device amplifies the audio signal. Its output is connected to control the first of the series-connected devices and the output terminal of the amplifier is connected through a resistive feedback path to the output of the third device. A further feedback system employs a carrier wave applied to the diaphragm of the transducer. The resulting signal on the electrodes is differentiated and negatively fed back to damp speaker response at low frequency resonance.
Inventors
- 👤 Harold N Beveridge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:29
CPC Classifications
H; H04; H04R; H04R3/00; H04R3/002; H03; H03F; H03F1/00; H03F1/34; H03F1/36; H03F3/00; H03F3/181; H03F3/183; H04R19/00; H04R19/02
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
174 words
An electrostatic loudspeaker comprising an electrostatic transducer having diaphragm surface portions which produce backward and forward moving sound radiation, an enclosure surrounding said transducer and adapted to contain the backward moving sound, an outlet passage for forward moving sound, said outlet passage having a throat that is substantially less in cross-sectional area than the collective area of said diaphragm surface portions, said outlet passage constructed and arranged with respect to said diaphragm surface portions to cause forward moving sound from each of said portions to pass through substantially equal length paths terminating beyond said throat at a projected common circle centered on said passage, the path for adjacent diaphragm surface portions terminating at adjacent segments of the arc of said projected circle, and wherein said passage is provided by a set of channels defined by walls, each channel associated with a predetermined diaphragm surface portion, channels associated with neighboring surface portions having their outlets in neighboring relation, the channels having constricted throat portions of cross-sectional area less than the area of their respective inlets.
Claim 2
Dependent Claim
174 words
An electrostatic loudspeaker comprising an electrostatic transducer having diaphragm surface portions which produce backward and forward moving sound radiation, an enclosure surrounding said transducer and adapted to contain the backward moving sound, an outlet passage for forward moving sound, said outlet passage having a throat that is substantially less in cross-sectional area than the collective area of said diaphragm surface portions, said outlet passage constructed and arranged with respect to said diaphragm surface portions to cause forward moving sound from each of said portions to pass through substantially equal length paths terminating beyond said throat at a projected common circle centered on said passage, the path for adjacent diaphragm surface portions terminating at adjacent segments of the arc of said projected circle, and wherein said passage is provided by a set of channels defined by walls, each channel associated with a predetermined diaphragm surface portion, channels associated with neighboring surface portions having their outlets in neighboring relation, the channels having constricted throat portions of cross-sectional area less than the area of their respective inlets.
Claim 3
Dependent Claim
25 words
The loudspeaker of claim 1 in which said channels extend outwardly from said throat portions to outlets that are larger than the respective throat portions.
Claim 4
Dependent Claim
213 words
An electrostatic loudspeaker comprising an electrostatic transducer having diaphragm surface portions which produce backward and forward moving sound radiation, an enclosure surrounding said transducer and adapted to contain the backward moving sound, an outlet passage for forward moving sound, said outlet passage having a throat that is substantially less in cross-sectional area than the collective area of said diaphragm surface portions, said outlet passage constructed and arranged with respect to said diaphragm surface portions to cause forward moving sound from each of said portions to pass through substantially equal length paths terminating beyond said throat at a projected common circle centered on said passage, the path for adjacent diaphragm surface portions terminating at adjacent segments of the arc of said projected circle, and wherein said diaphragm surface portions are arrayed within said enclosure to form substantially a segment of a circle, the inside surface of said circular array aligned with a spaced apart outlet aperture of said enclosure, said aperture being substantially smaller in width than the chord of said segment, and walls connecting the sides of said circular array to the corresponding sides of said aperture, whereby the paths normal to adjacent surface portions cross each other substantially at a common point and emanate radially therefrom to provide a circular wave front.
Claim 5
Dependent Claim
213 words
An electrostatic loudspeaker comprising an electrostatic transducer having diaphragm surface portions which produce backward and forward moving sound radiation, an enclosure surrounding said transducer and adapted to contain the backward moving sound, an outlet passage for forward moving sound, said outlet passage having a throat that is substantially less in cross-sectional area than the collective area of said diaphragm surface portions, said outlet passage constructed and arranged with respect to said diaphragm surface portions to cause forward moving sound from each of said portions to pass through substantially equal length paths terminating beyond said throat at a projected common circle centered on said passage, the path for adjacent diaphragm surface portions terminating at adjacent segments of the arc of said projected circle, and wherein said diaphragm surface portions are arrayed within said enclosure to form substantially a segment of a circle, the inside surface of said circular array aligned with a spaced apart outlet aperture of said enclosure, said aperture being substantially smaller in width than the chord of said segment, and walls connecting the sides of said circular array to the corresponding sides of said aperture, whereby the paths normal to adjacent surface portions cross each other substantially at a common point and emanate radially therefrom to provide a circular wave front.
Claim 6
Dependent Claim
111 words
An electrostatic loudspeaker comprising an electrostatic transducer having diaphragm surface portions which produce backward and forward moving sound radiation, an enclosure surrounding said transducer and adapted to contain the backward moving sound, an outlet passage for forward moving sound, said outlet passage having a throat that is substantially less in cross-sectional area than the collective area of said diaphragm surface portions, said passage is provided by a set of channels defined by walls, each channel associated with a predetermined diaphragm surface portion, channels associated with neighboring surface portions having their outlets in like relation, the channels having constricted throat portions of cross-sectional area less than the area of their respective inlets.
Claim 7
Dependent Claim
111 words
An electrostatic loudspeaker comprising an electrostatic transducer having diaphragm surface portions which produce backward and forward moving sound radiation, an enclosure surrounding said transducer and adapted to contain the backward moving sound, an outlet passage for forward moving sound, said outlet passage having a throat that is substantially less in cross-sectional area than the collective area of said diaphragm surface portions, said passage is provided by a set of channels defined by walls, each channel associated with a predetermined diaphragm surface portion, channels associated with neighboring surface portions having their outlets in like relation, the channels having constricted throat portions of cross-sectional area less than the area of their respective inlets.
Claim 8
Dependent Claim
39 words
The loudspeaker of claim 4 wherein said diaphragm portions and the cooperating outlet passage are each of elongated form in the direction perpendicular to said circle thereby adapted to generate substantially a cylindrical waveform dispersion of high frequency sound.
Claim 9
Dependent Claim
22 words
The loudspeaker of claim 4 wherein sAid diaphragm is at least about twice as wide as the minimum width of said throat.
Claim 10
Dependent Claim
86 words
The loudspeaker of claim 4 wherein said diaphragm surface portions are defined by an integral planar diaphragm, and said channels comprise middle channels extending substantially straight from middle portions of said planar diaphragm to their respective outlets and outer channels extending along curved paths from outer portions of the diaphragm, said outer channels having first portions gradually reducing in cross-sectional area and curving toward said middle channels and second portions gradually increasing in cross-sectional area and curving away from said middle channels toward their respective outlets.
Claim 11
Dependent Claim
22 words
The loudspeaker of claim 4 wherein the portions of said channels immediately adjacent said outlets have centerlines substantially intersecting at a point.
Claim 12
Dependent Claim
31 words
The loudspeaker of claim 8 wherein said point of intersection lies substantially in the plane of the front of said enclosure and said outlets are arranged substantially through a semicircular arc.
Claim 13
Dependent Claim
158 words
An electrostatic loudspeaker capable of emitting high frequencies comprising a diaphragm mounted adjacent at least a first electrode to form an electrostatic transducer in combination with a lens system adapted to convert the directional high frequency sound from said diaphragm into a substantially curved wave, said lens system comprising walls defining a set of channels, each channel associated with a predetermined portion of said diaphragm, channels associated with neighboring portions having their outlets in like relation, said channels comprising middle channels extending substantially straight from middle portions of said planar diaphragm to their respective outlets and outer channels extending along curved paths from outer portions of the diaphragm, first portions of said outer channels near said diaphragm having gradually reducing cross-sectional area and curving toward said middle channels and second portions of said channels having gradually increasing cross-sectional area and curving away from said middle channels toward the outlets of said channels for dispersing said high frequency sound.
Claim 14
Dependent Claim
158 words
An electrostatic loudspeaker capable of emitting high frequencies comprising a diaphragm mounted adjacent at least a first electrode to form an electrostatic transducer in combination with a lens system adapted to convert the directional high frequency sound from said diaphragm into a substantially curved wave, said lens system comprising walls defining a set of channels, each channel associated with a predetermined portion of said diaphragm, channels associated with neighboring portions having their outlets in like relation, said channels comprising middle channels extending substantially straight from middle portions of said planar diaphragm to their respective outlets and outer channels extending along curved paths from outer portions of the diaphragm, first portions of said outer channels near said diaphragm having gradually reducing cross-sectional area and curving toward said middle channels and second portions of said channels having gradually increasing cross-sectional area and curving away from said middle channels toward the outlets of said channels for dispersing said high frequency sound.
Claim 15
Dependent Claim
33 words
The loudspeaker of claim 10 wherein the minimum cross-sections of said channels occur at varying distances from said diaphragm thereby tending to reduce detrimental effects from reflections of sound passing through said channels.
Claim 16
Dependent Claim
46 words
The loudspeaker of claim 10 wherein said parts of said diaphragm surface and the entrances to the corresponding outer channels have widths corresponding generally to the length of the shortest wave length desired to be dispersed without distortion, said width being less than 1 1/2 inches.
Claim 17
Dependent Claim
56 words
The loudspeaker of claim 10 wherein said channels are constructed and arranged to cause forward moving sound from each of said parts of said diaphragm surface to pass through substantially equal length paths terminating at a common circle, the outer portions of said channels lying substantially on axes that intersect, defining the center of said circle.
Claim 18
Dependent Claim
40 words
The loudspeaker of claim 10 wherein said diaphragm and the channels defined by walls are each of elongated form in the direction perpendicular to said circle, thereby adapted to generate substantially a cylindrical wave for dispersion of high frequency sound.
Claim 19
Dependent Claim
199 words
An electrostatic loudspeaker capable of emitting low frequencies down to around 50 Hz comprising a wide diaphragm mounted adjacent to at least a first electrode to form an electrostatic transducer, an enclosure surrounding said transducer and adapted to contain the backward moving sound radiation, an extended air column defining outlet passage from said transducer adapted to conduct forward moving sound radiation out of said enclosure, said outlet passage having an entrance sized and positioned to conduct sound from a wide effective area of said diaphragm, said passage tapering gradually down to a throat of cross-sectional area substantially less than saId area of said diaphragm, said passage provided by a set of channels defined by walls, each channel associated with a predetermined diaphragm surface portion, channels associated with neighboring surface portions having their outlets in neighboring relation, the channels having constricted throat portions of cross-sectional area less than the area of their respective inlets, said enclosure sized to define an air volume exposed to the back of the diaphragm which is a plurality of times greater than the air volume confined by said outlet passage, said enclosure and throat adapted to establish a low frequency of resonance for said loudspeaker.
Claim 20
Dependent Claim
199 words
An electrostatic loudspeaker capable of emitting low frequencies down to around 50 Hz comprising a wide diaphragm mounted adjacent to at least a first electrode to form an electrostatic transducer, an enclosure surrounding said transducer and adapted to contain the backward moving sound radiation, an extended air column defining outlet passage from said transducer adapted to conduct forward moving sound radiation out of said enclosure, said outlet passage having an entrance sized and positioned to conduct sound from a wide effective area of said diaphragm, said passage tapering gradually down to a throat of cross-sectional area substantially less than saId area of said diaphragm, said passage provided by a set of channels defined by walls, each channel associated with a predetermined diaphragm surface portion, channels associated with neighboring surface portions having their outlets in neighboring relation, the channels having constricted throat portions of cross-sectional area less than the area of their respective inlets, said enclosure sized to define an air volume exposed to the back of the diaphragm which is a plurality of times greater than the air volume confined by said outlet passage, said enclosure and throat adapted to establish a low frequency of resonance for said loudspeaker.
Claim 21
Dependent Claim
48 words
The loudspeaker of claim 15 wherein the portion of the volume of said enclosure that is exposed to the back surface of said diaphragm is at least about four times greater than the portion of the volume of said enclosure exposed to the front surface of said diaphragm.
Claim 22
Dependent Claim
162 words
An electrostatic loudspeaker wherein two electrodes are provided, one on each side of a diaphragm mounted under self-restoring tension in a balanced transducer construction, each of said electrodes being comprised of a dielectric portion directed toward said diaphragm and a conductive layer disposed on the outer side of said dielectric portion, each electrode comprising a matrix of dielectric material and a dispersion through said matrix of a substance having a dielectric constant greater than about 500, each electrode having molded therein a plurality of apertures through which sound can escape from said diaphragm, each of said dielectric portions having a thickness greater than about 3 times the thickness of the air gap between the respective electrode and the diaphragm in mid-position, the dielectric portions having a dielectric constant greater than about 30, and means for applying a polarizing voltage between said conductive layers of said electrodes, and an audio amplifier connected to apply amplified audio signals between said diaphragm and the electrodes.
Claim 23
Dependent Claim
162 words
An electrostatic loudspeaker wherein two electrodes are provided, one on each side of a diaphragm mounted under self-restoring tension in a balanced transducer construction, each of said electrodes being comprised of a dielectric portion directed toward said diaphragm and a conductive layer disposed on the outer side of said dielectric portion, each electrode comprising a matrix of dielectric material and a dispersion through said matrix of a substance having a dielectric constant greater than about 500, each electrode having molded therein a plurality of apertures through which sound can escape from said diaphragm, each of said dielectric portions having a thickness greater than about 3 times the thickness of the air gap between the respective electrode and the diaphragm in mid-position, the dielectric portions having a dielectric constant greater than about 30, and means for applying a polarizing voltage between said conductive layers of said electrodes, and an audio amplifier connected to apply amplified audio signals between said diaphragm and the electrodes.
Claim 24
Dependent Claim
21 words
The loudspeaker of claim 17 wherein said electrode has a volumetric resistivity in the range of 108 to 1011 ohm centimeters.
Claim 25
Dependent Claim
103 words
An electrostatic loudspeaker transducer comprising a flexible diaphragm mounted under self-restoring tension, at least one rigid electrode facing the diaphragm and having a conductive surface on its opposite side, energization means for applying a polarizing voltage and an audio signal to cause corresponding vibration of the diaphragm to produce sound, the electrode comprising a matrix of dielectric material and a dispersion through said matrix of a substance having a dielectric constant greater than about 500, said electrode having molded therein a plurality of apertures through which sound can escape from said diaphragm, said electrode having an overall dielectric constant greater than about 30.
Claim 26
Dependent Claim
103 words
An electrostatic loudspeaker transducer comprising a flexible diaphragm mounted under self-restoring tension, at least one rigid electrode facing the diaphragm and having a conductive surface on its opposite side, energization means for applying a polarizing voltage and an audio signal to cause corresponding vibration of the diaphragm to produce sound, the electrode comprising a matrix of dielectric material and a dispersion through said matrix of a substance having a dielectric constant greater than about 500, said electrode having molded therein a plurality of apertures through which sound can escape from said diaphragm, said electrode having an overall dielectric constant greater than about 30.
Claim 27
Dependent Claim
38 words
The electrostatic loudspeaker of claim 19 wherein said electrode contains a dispersion of another substance having a lower volume resistivity than said matrix material, thereby reducing the volume resistivity of said electrode below that of said matrix material.
Claim 28
Dependent Claim
81 words
The loudspeaker transducer of claim 19 including a second electrode of like construction assembled with said first electrode and said diaphragm to provide a balanced construction with the diaphragm disposed between said electrodes, an enclosure surrounding said transducer constructed to contain backward moving radiation from said diaphragm, an outlet throat from said enclosure for sound from said diaphragm, said throat being substantially narrower than said diaphragm, said energization means adapted to apply a voltage greater than 2,000 volts across said electrodes.
Claim 29
Dependent Claim
76 words
The electrostatic loudspeaker of claim 15 wherein, with respect to adjacent surface portions of said diaphragm, said outlet passage is constructed and arranged to cause forward moving sound from each of said adjacent surface portions of said diaphragm to pass Through substantially equal length paths terminating beyond said throat at a projected common circle centered on said passage, the paths for adjacent diaphragm surface portions terminating at adjacent segments of the arc of said projected circle.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |