US3794967A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intruder alarm for automobiles
Assignee: Individual
•
Filing: 1972-08-03
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Granted: 1974-02-26
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Expires: 1992-08-03
Abstract
Abstract An intruder alarm particularly suited for installation in an automobile. The alarm includes a transistor connected to the Aline of an automobile electrical system in an inverse manner, i.e., emitter-base reverse biased, to detect A-line transients. The sensor can be made sensitive to body contact by wiring to insulated portions of the automobile or to a pressure sensitive capacitor. A latching circuit, controlled by the sensor, actuates the automobile horn whenever the sensor detects an A-line transient or is otherwise disturbed by an intruder. Timing circuits modify the horn action so that an alarm signal is distinguishable from a fault in the horn circuit.
Inventors
- 👤 L Fischer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:10
CPC Classifications
B; B60; B60R; B60R25/00; B60R25/10; B60R25/1004; B60R2025/1013; B60R25/1001; B60R25/1003
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
212 words
In a theft alarm which includes means for detecting a sudden change in an electrical characteristic of a bipolar direct current circuit associated with the alarm for triggering the alarm into operation, improved detecting means comprising a transistor having an emitter electrode composed of one conductivity type of semiconductor material, a base electrode composed of the opposite conductivity type of semiconductor material and a collector electrode composed of said one conductivity type of semiconductor material, said emitter electrode being connected to the pole of said direct current circuit having a polarity opposite the conductivity type of semiconductor of which said emitter is composed, said collector electrode being connected to the other pole of said direct current circuit, said other pole being of the same polarity as the type of semiconductor of which said collector is composed, and means including a high impedance connecting said base electrode to said other pole of said direct current circuit to which said collector electrode is connected, a capacitor connected between said emitter and said collector electrodes of said transistor and a latching circuit having an input connected to said transistor to receive an impulse therefrom wheneveR the electrical equilibrium of said transistor is disturbed, said impulse rendering said latching circuit continuously conductive to operate said alarm.
Claim 2
Dependent Claim
212 words
In a theft alarm which includes means for detecting a sudden change in an electrical characteristic of a bipolar direct current circuit associated with the alarm for triggering the alarm into operation, improved detecting means comprising a transistor having an emitter electrode composed of one conductivity type of semiconductor material, a base electrode composed of the opposite conductivity type of semiconductor material and a collector electrode composed of said one conductivity type of semiconductor material, said emitter electrode being connected to the pole of said direct current circuit having a polarity opposite the conductivity type of semiconductor of which said emitter is composed, said collector electrode being connected to the other pole of said direct current circuit, said other pole being of the same polarity as the type of semiconductor of which said collector is composed, and means including a high impedance connecting said base electrode to said other pole of said direct current circuit to which said collector electrode is connected, a capacitor connected between said emitter and said collector electrodes of said transistor and a latching circuit having an input connected to said transistor to receive an impulse therefrom wheneveR the electrical equilibrium of said transistor is disturbed, said impulse rendering said latching circuit continuously conductive to operate said alarm.
Claim 3
Dependent Claim
38 words
The improvement claimed in claim 1 wherein said collector of said transistor is connected to said other pole of said direct current circuit through a high resistance and said high impedance connecting said base electrode comprises a capacitor.
Claim 4
Dependent Claim
55 words
The improvement claimed in claim 2 with additionally a conductor connected to said base of said transistor and insulated from said direct current circuit said conductor being so disposed as to be liable to be touched by a person unadvised of its existence, thereby disturbing the electrical equilibrium of said transistor and triggering said alarm.
Claim 5
Dependent Claim
19 words
The improvement of claim 1 wherein said direct current circuit is a battery powered electrical system for a vehicle.
Claim 6
Dependent Claim
30 words
The improvement of claim 1 with additionally means operable upon operation of said latching circuit for periodically interrupting operation of said latching circuit to provide an alarm of intermittent character.
Claim 7
Dependent Claim
36 words
The improved alarm of claim 5 with additionally, means operable upon operation of said latching circuit for terminating operation of said latching circuit and said alarm after a fixed period of intermittent operation of said alarm.
References Cited (Backward Citations)
US3706966A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |