US5548654A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Infrared audio transmitter system
Assignee: Individual
•
Filing: 1994-04-07
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Granted: 1996-08-20
•
Expires: 2014-04-07
Abstract
Abstract An infrared assistive listening system capable of enhanced performance in medium-sized locations, such as courtrooms, classrooms, and conference rooms, is realized by a system comprising a pressure zone microphone capable of picking up distant speakers, a high-gain pre-amplifier, an equalization and pre-emphasis circuit, an automatic gain control and limiting circuit, a mute feature capable of remote activation, a FM modulator, a pulse width modulator, and a high-power single front throw infrared emitter. Another embodiment of the invention employs an multi-directional infrared emitter array in conjunction with the single front throw emitter.
Inventors
- 👤 Lawrence R. Fast
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:08
CPC Classifications
H; H04; H04R; H04R3/00
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
141 words
An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising: means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals; oscillator means for generating a base carrier electrical signal; means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle; emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal; and means for adjusting the duty cycle of said modulated electrical signal so as to adjust the current through said emitter means and thereby limit the power dissipation of said emitter means.
Claim 2
Dependent Claim
141 words
An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising: means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals; oscillator means for generating a base carrier electrical signal; means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle; emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal; and means for adjusting the duty cycle of said modulated electrical signal so as to adjust the current through said emitter means and thereby limit the power dissipation of said emitter means.
Claim 3
Dependent Claim
24 words
The assistive listening system of claim 1 wherein said means for modulating frequency modulates said base carrier electrical signal with said audio electrical signal.
Claim 4
Dependent Claim
24 words
The assistive listening system of claim 1 wherein said emitter means draws current in accordance with the duty cycle of said modulated electrical signal.
Claim 5
Dependent Claim
30 words
The assistive listening system of claim 1 further comprising automatic gain control means for adjusting the signal strength of the upper and lower frequency signals of said audio electrical signal.
Claim 6
Dependent Claim
16 words
The assistive listening system of claim 4 wherein said automatic gain control means includes an opto-isolator.
Claim 7
Dependent Claim
15 words
The assistive listening system of claim 1 wherein said means for converting includes a microphone.
Claim 8
Dependent Claim
39 words
The assistive listening system of claim 6 wherein said microphone is a pressure zone microphone capable of converting the audio sound waves to said audio electrical signal by reflecting said audio sound waves off a closely mounted boundary plate.
Claim 9
Dependent Claim
31 words
The assistive listening system of claim 1 further comprising pre-emphasis means for amplifying and reducing the signal strength of the upper and lower frequency signals, respectively, of said audio electrical signal.
Claim 10
Dependent Claim
28 words
The assistive listening system of claim 8 where said pre-emphasis means for amplifying and reducing has an upper frequency boost at a time constant of approximately 50 μsec.
Claim 11
Dependent Claim
26 words
The assistive listening system of claim 1 wherein said means for modulating includes a FM modulator utilizing the voltage-controlled oscillator section of a phase locked loop.
Claim 12
Dependent Claim
15 words
The assistive listening system of claim 1 wherein said emitter means includes MOSFET power transistors.
Claim 13
Dependent Claim
12 words
The assistive listening system of claim 1 wherein said system is battery-powered.
Claim 14
Dependent Claim
153 words
An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising: means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals; oscillator means for generating a base carrier electrical signal; means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle; and emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal, and said emitter means including a single front throw emitter for transmitting said infrared light signal substantially along a single direction, and a multi-directional emitter array for transmitting said infrared light signal at least along the rear and sides of said single direction.
Claim 15
Dependent Claim
153 words
An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising: means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals; oscillator means for generating a base carrier electrical signal; means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle; and emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal, and said emitter means including a single front throw emitter for transmitting said infrared light signal substantially along a single direction, and a multi-directional emitter array for transmitting said infrared light signal at least along the rear and sides of said single direction.
Claim 16
Dependent Claim
31 words
The assistive listening system of claim 13 further comprising means for adjusting the duty cycle of said modulated electrical signal so as to limit the power dissipation of said emitter means.
Claim 17
Dependent Claim
24 words
The assistive listening system of claim 13 wherein said means for modulating frequency modulates said base carrier electrical signal with said audio electrical signal.
Claim 18
Dependent Claim
24 words
The assistive listening system of claim 13 wherein said emitter means draws current in accordance with the duty cycle of said modulated electrical signal.
Claim 19
Dependent Claim
30 words
The assistive listening system of claim 13 further comprising automatic gain control means for adjusting the signal strength of the upper and lower frequency signals of said audio electrical signal.
Claim 20
Dependent Claim
16 words
The assistive listening system of claim 17 wherein said automatic gain control means includes an opto-isolator.
Claim 21
Dependent Claim
15 words
The assistive listening system of claim 13 wherein said means for converting includes a microphone.
Claim 22
Dependent Claim
39 words
The assistive listening system of claim 19 wherein said microphone is a pressure zone microphone capable of converting the audio sound waves to said audio electrical signal by reflecting said audio sound waves off a closely mounted boundary plate.
Claim 23
Dependent Claim
31 words
The assistive listening system of claim 13 further comprising pre-emphasis means for amplifying and reducing the signal strength of the upper and lower frequency signals, respectively, of said audio electrical signal.
Claim 24
Dependent Claim
28 words
The assistive listening system of claim 21 where said pre-emphasis means for amplifying and reducing has an upper frequency boost at a time constant of approximately 50 μsec.
Claim 25
Dependent Claim
26 words
The assistive listening system of claim 13 wherein said means for modulating includes a FM modulator utilizing the voltage-controlled oscillator section of a phase locked loop.
Claim 26
Dependent Claim
15 words
The assistive listening system of claim 13 wherein said emitter means includes MOSFET power transistors.
Claim 27
Dependent Claim
18 words
The assistive listening system of claim 13 wherein said single front throw emitter includes a GaAlAs infrared emitter.
Claim 28
Dependent Claim
19 words
The assistive listening system of claim 13 wherein said multi-directional emitter array includes a circular array of infrared LEDs.
Claim 29
Dependent Claim
12 words
The assistive listening system of claim 13 wherein said system is battery-powered.
Claim 30
Dependent Claim
148 words
An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising: means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals; oscillator means for generating a base carrier electrical signal; means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle; emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal; mute means responsive to a control signal for selectively disabling said means for modulating while allowing the transmission of said base carrier electrical signal so as to cease audio transmission; and remote control means for generating said control signal.
Claim 31
Dependent Claim
148 words
An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising: means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals; oscillator means for generating a base carrier electrical signal; means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle; emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal; mute means responsive to a control signal for selectively disabling said means for modulating while allowing the transmission of said base carrier electrical signal so as to cease audio transmission; and remote control means for generating said control signal.
Claim 32
Dependent Claim
31 words
The assistive listening system of claim 28 further comprising means for adjusting the duty cycle of said modulated electrical signal so as to limit the power dissipation of said emitter means.
Claim 33
Dependent Claim
24 words
The assistive listening system of claim 28 wherein said means for modulating frequency modulates said base carrier electrical signal with said audio electrical signal.
Claim 34
Dependent Claim
24 words
The assistive listening system of claim 28 wherein said emitter means draws current in accordance with the duty cycle of said modulated electrical signal.
Claim 35
Dependent Claim
30 words
The assistive listening system of claim 28 further comprising automatic gain control means for adjusting the signal strength of the upper and lower frequency signals of said audio electrical signal.
Claim 36
Dependent Claim
16 words
The assistive listening system of claim 32 wherein said automatic gain control means includes an opto-isolator.
Claim 37
Dependent Claim
15 words
The assistive listening system of claim 28 wherein said means for converting includes a microphone.
Claim 38
Dependent Claim
39 words
The assistive listening system of claim 28 wherein said microphone is a pressure zone microphone capable of converting the audio sound waves to said audio electrical signal by reflecting said audio sound waves off a closely mounted boundary plate.
Claim 39
Dependent Claim
31 words
The assistive listening system of claim 28 further comprising pre-emphasis means for amplifying and reducing the signal strength of the upper and lower frequency signals, respectively, of said audio electrical signal.
Claim 40
Dependent Claim
28 words
The assistive listening system of claim 36 where said pre-emphasis means for amplifying and reducing has an upper frequency boost at a time constant of approximately 50 μsec.
Claim 41
Dependent Claim
26 words
The assistive listening system of claim 28 wherein said means for modulating includes a FM modulator utilizing the voltage-controlled oscillator section of a phase locked loop.
Claim 42
Dependent Claim
15 words
The assistive listening system of claim 28 wherein said emitter means includes MOSFET power transistors.
Claim 43
Dependent Claim
12 words
The assistive listening system of claim 28 wherein said system is battery-powered.
References Cited (Backward Citations)
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JPH01126028A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-08-20 | 2000-02-19 | 2000-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-08-20 | 2004-02-19 | 2004-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-08-20 | 2008-02-19 | 2008-08-20 | $7700.00 | Window Closed / Lapsed |