Patent US3825918A successfully refreshed from Google Patents.
US3825918A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impact sensitive security window system
Assignee: Sierracin Corp
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Filing: 1972-11-16
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Granted: 1974-07-23
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Expires: 1992-11-16
Abstract
Abstract A security window system having a transparent structure having high resistance to penetration is described. A transparent conductive layer is provided over most of the area of the window and the resistance of the layer is monitored for sensing penetration. Preferably the layer is subdivided into a number of conductive regions for substantially increasing the sensitivity of the system to minor interruptions in the layer. Temperature and stress effects can be minimized by connecting different conductive areas of the layers as arms of a resistance bridge. An alarm may be sounded when a small steady state change in resistance is sensed or when a rapid change in resistance is sensed.
Inventors
- 👤 H Laidlaw
- 👤 B Levin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:26
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/02; G08B13/04; B; B32; B32B; B32B17/00; B32B17/06; B32B17/10; B32B17/10005; B32B17/10009; B32B17/10036; B32B17/10082; B32B17/10091; B32B17/10165; B32B17/10174; B32B17/1055; B32B17/10761
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
75 words
An impact sensitive security window system comprising: a transparent electrically conductive layer extending over most of the area of the window; means for monitoring resistance of the conductive layer; and means connected to the means for monitoring for giving an output signal in response to a rapid change in resistance such as to produce, at the output of said means for monitoring, a pulse having a predetermined pulse characteristic in excess of a predetermined threshold.
Claim 2
Dependent Claim
75 words
An impact sensitive security window system comprising: a transparent electrically conductive layer extending over most of the area of the window; means for monitoring resistance of the conductive layer; and means connected to the means for monitoring for giving an output signal in response to a rapid change in resistance such as to produce, at the output of said means for monitoring, a pulse having a predetermined pulse characteristic in excess of a predetermined threshold.
Claim 3
Dependent Claim
27 words
A security window system as defined in claim 1 wherein the means for giving an output signal comprises an AC amplifier connected to the electrically conductive layer.
Claim 4
Dependent Claim
34 words
A security window system as defined in claim 2 wherein said means for giving an output signal comprises a threshold detector connected to the AC amplifier and an alarm responsive to the threshold detector.
Claim 5
Dependent Claim
29 words
A security window system as defined in claim 2 wherein the means for giving an output signal includes means for producing an analog output signal perceptible by a person.
Claim 6
Dependent Claim
48 words
A security window system as defined in claim 2 further comprising means for adjusting the means for giving an output signal for providing an output signal only when the magnitude of the pulse exceeds a predetermined fraction of the pulse that would occur upon penetration of the window.
Claim 7
Dependent Claim
36 words
A security window system as defined in claim 5 further comprising means connected to the conductive layer for giving an output signal in response to an accumulated change in resistance in excess of a predetermined magnitude.
Claim 8
Dependent Claim
70 words
A security window system comprising: an electrically conductive transparent layer extending over most of the area of the window, said layer having an electrical property changeable in response to strain of the window; means connected to the conductive layer for detecting a change in the electrical property; and means connected to the means for detecting for giving an output signal when the strain of the window exceeds a predetermined limit.
Claim 9
Dependent Claim
70 words
A security window system comprising: an electrically conductive transparent layer extending over most of the area of the window, said layer having an electrical property changeable in response to strain of the window; means connected to the conductive layer for detecting a change in the electrical property; and means connected to the means for detecting for giving an output signal when the strain of the window exceeds a predetermined limit.
Claim 10
Dependent Claim
33 words
A security window system as defined in claim 7 wherein the means for detecting comprises means for detecting a transient change in resistance of the conductive layer in excess of a predetermined limit.
Claim 11
Dependent Claim
44 words
A security window system as defined in claim 7 wherein the conductive layer comprises a thin metal film deposited on a transparent carrier film and wherein the carrier film is laminated in the window off of the neutral axis of the window cross section.
Claim 12
Dependent Claim
33 words
A security window system as defined in claim 9 wherein the means for detecting comprises means for detecting a transient change in resistance of the metal film in excess of a predetermined limit.
Claim 13
Dependent Claim
34 words
A security window system as defined in claim 7 further comprising means connected to the electrically conductive layer for giving an output signal when the equilibrium resistance of the layer exceeds a predetermined limit.
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) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |