Patent US3750131A successfully refreshed from Google Patents.
US3750131A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silent emergency alarm system for schools and the like
Assignee: National Aeronautics and Space Administration
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Filing: 1971-08-06
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Granted: 1973-07-31
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Expires: 1991-08-06
Abstract
Abstract In a school each classroom (or other area) is instrumented with a hidden microphone and receiver tuned to a non-audible frequency. The receivers'' outputs are connected to a central display unit in the school''s administrative office. Each instructor is provided with a small concealable transmitter which, when hand activated by the instructor upon the occurrence of any emergency, generates a non-audible signal at the receiver''s tuned frequency.
Inventors
- 👤 J Fletcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:26
CPC Classifications
G; G08; G08B; G08B25/00; G08B25/01; G08B25/016
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
184 words
In a stationary structure defining a plurality of discrete stationary locations and a central stationary location, a method of indicating at said central location the existence of an emergency in any of said discrete locations, the method including the steps of: providing in each of said discrete stationary locations fixedly located detection means for detecting a supersonic signal generated therein; providing in said central location display means, which are directly connected by means of continuous wires to the detection means in the various discrete locations, and which include a plurality of indicators, each associated with a different detection means and energized when the detection means with which it is associated detects a supersonic signal; generating in each discrete stationary location at which an emergency exists a supersonic signal which is detected by the detection means in the discrete location; providing audio means in at least one of said discrete stationary locations, said audio means including a variabe gain audio amplifier; and automatically increasing the gain of said amplifier when the detection means in the stationary location detect a supersonic signal which is generated therein.
Claim 2
Dependent Claim
184 words
In a stationary structure defining a plurality of discrete stationary locations and a central stationary location, a method of indicating at said central location the existence of an emergency in any of said discrete locations, the method including the steps of: providing in each of said discrete stationary locations fixedly located detection means for detecting a supersonic signal generated therein; providing in said central location display means, which are directly connected by means of continuous wires to the detection means in the various discrete locations, and which include a plurality of indicators, each associated with a different detection means and energized when the detection means with which it is associated detects a supersonic signal; generating in each discrete stationary location at which an emergency exists a supersonic signal which is detected by the detection means in the discrete location; providing audio means in at least one of said discrete stationary locations, said audio means including a variabe gain audio amplifier; and automatically increasing the gain of said amplifier when the detection means in the stationary location detect a supersonic signal which is generated therein.
Claim 3
Dependent Claim
179 words
In combination with a stationary structure defining a plurality of discrete stationary chambers each adapted to be occupied by a plurality of individuals and a stationary control location, a system for indicating at said control location the existence of an emergency in any of said chambers, the system comprising: separate detection means installed in each stationary chamber for detecting a non-audible signal generated therein; control means located in said control location, directly coupled to said separate detection means and including a separate energizable indicator for each separate detection means installed in each chamber, said control means further including means for energizing each indicator associated with a detection means which detects a non-audible signal; signal generating means in each discrete stationary location for generating a non-audible signal therein; and audio means associated with at least one of said stationary chambers, said audio means including a variable gain audio amplifier, and means for coupling said amplifier to the detection means in said chamber with the gain of said amplifier increasing when the detection means detect a non-audible signal in said chamber.
Claim 4
Dependent Claim
179 words
In combination with a stationary structure defining a plurality of discrete stationary chambers each adapted to be occupied by a plurality of individuals and a stationary control location, a system for indicating at said control location the existence of an emergency in any of said chambers, the system comprising: separate detection means installed in each stationary chamber for detecting a non-audible signal generated therein; control means located in said control location, directly coupled to said separate detection means and including a separate energizable indicator for each separate detection means installed in each chamber, said control means further including means for energizing each indicator associated with a detection means which detects a non-audible signal; signal generating means in each discrete stationary location for generating a non-audible signal therein; and audio means associated with at least one of said stationary chambers, said audio means including a variable gain audio amplifier, and means for coupling said amplifier to the detection means in said chamber with the gain of said amplifier increasing when the detection means detect a non-audible signal in said chamber.
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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |