US3934237A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alarm device
Assignee: Bevaknings AB Securitas
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Filing: 1974-03-06
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Granted: 1976-01-20
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Expires: 1994-03-06
Abstract
Abstract An alarm device comprising a first program mechanism at a monitored station and a second program mechanism at a central monitoring station. The program mechanisms have identical shift registers and identical feedback networks and generate binary signals according to a predetermined arbitrary law. A sensing device is connected to the first program mechanism to cause a departure of the binary signals from the predetermined arbitrary law in the presence of a disturbance. The binary signals from the first program mechanism are compared with the output of the second program mechanism, and an alarm is produced if the outputs are different.
Inventors
- 👤 Bjorn Gysell
- 👤 Matz Pehrsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:06
CPC Classifications
G; G08; G08B; G08B25/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
227 words
An alarm device comprising a first program mechanism at a monitored station and a second program mechanism at a central monitoring station, which program mechanisms are arranged to transmit control signals in accordance with a predetermined signal pattern to a signal comparison circuit arranged to generate an alarm signal when the received control signals differ from one another, the first and the second program mechamisms being provided with identical electric shift registers with a plurality of binary denominational steps and identically connected feed-back networks, each program mechanism being arranged to generate a binary one or zero signal in dependence on the content of the respective shift register, said binary signals constituting discrete control signals, the control signal from the first program mechanism being coupled to a transmitter at said monitored station arranged to transmit an analogous signal to a receiver at the central monitoring station, which receiver converts the analogous signal to an output signal identical with the original binary control signal, which output signal is coupled to the second program mechanism to step the shift register thereof to generate a control signal, which together with the output signal of the receiver, is coupled to the signal comparison circuit, and wherein a timing mechanism is arranged to generate an alarm signal in the absence of an output signal from the receiver after a predetermined period of time.
Claim 2
Dependent Claim
227 words
An alarm device comprising a first program mechanism at a monitored station and a second program mechanism at a central monitoring station, which program mechanisms are arranged to transmit control signals in accordance with a predetermined signal pattern to a signal comparison circuit arranged to generate an alarm signal when the received control signals differ from one another, the first and the second program mechamisms being provided with identical electric shift registers with a plurality of binary denominational steps and identically connected feed-back networks, each program mechanism being arranged to generate a binary one or zero signal in dependence on the content of the respective shift register, said binary signals constituting discrete control signals, the control signal from the first program mechanism being coupled to a transmitter at said monitored station arranged to transmit an analogous signal to a receiver at the central monitoring station, which receiver converts the analogous signal to an output signal identical with the original binary control signal, which output signal is coupled to the second program mechanism to step the shift register thereof to generate a control signal, which together with the output signal of the receiver, is coupled to the signal comparison circuit, and wherein a timing mechanism is arranged to generate an alarm signal in the absence of an output signal from the receiver after a predetermined period of time.
Claim 3
Dependent Claim
176 words
An alarm system, comprising: first program means at a monitored station adapted to generate binary signals in accordance with a predetermined arbitrary law; sensing means connected to said first program means to cause a departure of said binary signals from said predetermined arbitrary law in the presence of a disturbance; transmitter means at said monitored station for transmitting said binary signals to a monitoring station; receiver means at said monitoring station for receiving said binary signals; second program means connected to said receiver means and clocked by said received binary signals to generate the same binary signals as those generated by said first program means in accordance with said predetermined arbitrary law, said first and second program means being of identical construction comprising a shift register and a feedback network connected thereto; comparator means for comparing said received binary signals with the output of said second program means; and alarm means controlled by said comparator means for actuation upon detection of a difference between said received binary signals and the output of said second program means.
Claim 4
Dependent Claim
176 words
An alarm system, comprising: first program means at a monitored station adapted to generate binary signals in accordance with a predetermined arbitrary law; sensing means connected to said first program means to cause a departure of said binary signals from said predetermined arbitrary law in the presence of a disturbance; transmitter means at said monitored station for transmitting said binary signals to a monitoring station; receiver means at said monitoring station for receiving said binary signals; second program means connected to said receiver means and clocked by said received binary signals to generate the same binary signals as those generated by said first program means in accordance with said predetermined arbitrary law, said first and second program means being of identical construction comprising a shift register and a feedback network connected thereto; comparator means for comparing said received binary signals with the output of said second program means; and alarm means controlled by said comparator means for actuation upon detection of a difference between said received binary signals and the output of said second program means.
Claim 5
Dependent Claim
32 words
The system of claim 2 further comprising another alarm means connected to said receiver means to generate an alarm signal in the absence of said received signals for a predetermined time period.
Claim 6
Dependent Claim
27 words
The system of claim 2 wherein each feedback network comprises an exclusive-OR circuit having two inputs connected to the first and last stages of said shift register.
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) | 1979-01-19 | 1979-07-21 | 1980-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-19 | 1983-07-21 | 1984-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-19 | 1987-07-21 | 1988-01-20 | $7700.00 | Window Closed / Lapsed |