Patent US3725892A successfully refreshed from Google Patents.
US3725892A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Door knob burglar alarm
Assignee: Allied Trading Co
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Filing: 1971-04-26
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Granted: 1973-04-03
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Expires: 1991-04-26
Abstract
Abstract An alarm device designed for temporary placement over a conventional doorknob in frictional engagement therewith. A pair of normally open mercury switches are operatively connected through batteries to an annunciating buzzer, and unauthorized rotation of the doorknob in either direction closes one of the switches to actuate the buzzer.
Inventors
- 👤 F Faltico
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:31
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/02; G08B13/06; Y; Y10; Y10S; Y10S70/00; Y10S70/58
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
204 words
An alarm device for placement on a door knob or the like, comprising: a. an alarm housing having a receptacle formed therein, the receptacle being sized to fit over a door knob and lined at least in part with a predetermined thickness of resilient, material disposed for frictional engagement with the door knob to permit movement of the alarm housing with rotational motion of the door knob; b. electric circuit means disposed within the alarm housing and comprising 1. battery means; 2. annunciator means; 3. first and second mercury switch means for closing the circuit between the battery means and the annunciator means, each of said mercury switch means occupying a normally open position with the alarm housing in a no-alarm position; 4. the first mercury switch means being disposed for closing movement in response to rotation of the housing in a first direction; 5. the second means being disposed for closing movement in response to rotation of the housing in an opposite direction; 6. each of said mercury switch means being angularly adjustable to determine the rotational position at which it closes; 7. and an on-off switch disposed to override the first and second mercury switch means and render said annunciator means inoperable.
Claim 2
Dependent Claim
204 words
An alarm device for placement on a door knob or the like, comprising: a. an alarm housing having a receptacle formed therein, the receptacle being sized to fit over a door knob and lined at least in part with a predetermined thickness of resilient, material disposed for frictional engagement with the door knob to permit movement of the alarm housing with rotational motion of the door knob; b. electric circuit means disposed within the alarm housing and comprising 1. battery means; 2. annunciator means; 3. first and second mercury switch means for closing the circuit between the battery means and the annunciator means, each of said mercury switch means occupying a normally open position with the alarm housing in a no-alarm position; 4. the first mercury switch means being disposed for closing movement in response to rotation of the housing in a first direction; 5. the second means being disposed for closing movement in response to rotation of the housing in an opposite direction; 6. each of said mercury switch means being angularly adjustable to determine the rotational position at which it closes; 7. and an on-off switch disposed to override the first and second mercury switch means and render said annunciator means inoperable.
Claim 3
Dependent Claim
14 words
The alarm device defined by claim 1, wherein the annunciator means comprises a buzzer.
Claim 4
Dependent Claim
2 words
annunciator means;
Claim 5
Dependent Claim
2 words
annunciator means;
Claim 6
Dependent Claim
37 words
first and second mercury switch means for closing the circuit between the battery means and the annunciator means, each of said mercury switch means occupying a normally open position with the alarm housing in a no-alarm position;
Claim 7
Dependent Claim
37 words
first and second mercury switch means for closing the circuit between the battery means and the annunciator means, each of said mercury switch means occupying a normally open position with the alarm housing in a no-alarm position;
Claim 8
Dependent Claim
14 words
The alarm device defined by claim 1, wherein the resilient, material comprises foam rubber.
Claim 9
Dependent Claim
21 words
the first mercury switch means being disposed for closing movement in response to rotation of the housing in a first direction;
Claim 10
Dependent Claim
21 words
the first mercury switch means being disposed for closing movement in response to rotation of the housing in a first direction;
Claim 11
Dependent Claim
35 words
The alarm device defined by claim 1, wherein each of said first and second mercury switch means is carried by a supporting clip which is rotatably mounted on a backing plate secured to the housing.
Claim 12
Dependent Claim
19 words
the second means being disposed for closing movement in response to rotation of the housing in an opposite direction;
Claim 13
Dependent Claim
19 words
the second means being disposed for closing movement in response to rotation of the housing in an opposite direction;
Claim 14
Dependent Claim
18 words
each of said mercury switch means being angularly adjustable to determine the rotational position at which it closes;
Claim 15
Dependent Claim
18 words
each of said mercury switch means being angularly adjustable to determine the rotational position at which it closes;
Claim 16
Dependent Claim
20 words
and an on-off switch disposed to override the first and second mercury switch means and render said annunciator means inoperable.
Claim 17
Dependent Claim
20 words
and an on-off switch disposed to override the first and second mercury switch means and render said annunciator means inoperable.
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) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |