GB2051445A - A surveillance system - Google Patents

Abstract

A surveillance system comprises a main station and a number of substations 1 which are cyclically interrogated by an address signal emitted by the main station and which respond thereto by emitting a code modulated high frequency signal, each substation 1 being provided with a resettable timer device 9 which after being started delivers after a predetermined first period a control signal to activate an acoustical or optical signalling device 19, 20 and delivers subsequently after a second period a control signal to activate the alarm circuit 3 of the substation 1. In this way the user at a substation can vary the time lapse before further action must be taken and in the event that such action is not taken the alarm circuit 3 is automatically activated. <IMAGE>

Description

SPECIFICATION Surveillance system This invention relates to a surveillance system comprising a main station and a number of substations, each substation having a transceiver coupled to an alarm circuit by means of which the state of the substations can be reported to the main station when the substations are cyclically interrogated by means of an address signal emitted by the emitter of the main station, the selected substation emitting a high frequency signal modulated with a code characterising the state of the substation to the main station.

Such a surveillance system is known in itself e.g. from the Dutch Patent Specification 156,258.

In such a surveillance system the substations are located in the rooms or houses of older people who live normally among other people but of which the state of health and/or their age is such that the chance of sudden illness or accidents is considerably greater than for younger people. Each such substation is provided with an alarm circuit connected to detectors or devices which can supply an alarm signal in case of fire or e.g. burglary and which are also provided with an alarm switch which can be operated by the user in case of accidents or sudden illness. By means of these devices the station can be brought in the so-called alarm state which is reported to the main station whereafter suitable measures can be taken.

However, it regularly occurs that people become ill and incapacitated so suddenly that they cannot reach the alarm switch or are unable to operate this switch and it is, of course, most desirable that in such a case provision should be made for informing the main station that a state of alarm exists at the corresponding substation.

According to the present invention, there is provided a surveillance system comprising a main station having an emitter and a number of substations, each substation having a transceiver coupled to an alarm circuit by means of which the state of the substations can be reported to the main station when the substations are cyclically interrogated by means of an address signal emitted by the emitter of the main station, and a resettable timer device, the interrogated substation emitting a high frequency signal modulated with a code characterising the state of the substation to the main station, and the resettable timer device after being started being operative to deliver after a predetermined first period a control signal to activate a signalling device and to deliver subsequently after a second period a control signal operative to activate the alarm circuit of the substation.

The fact that a new period can be started at will by resetting the timer ensures the user substantial freedom; the moment at which the predetermined action is performed can be adapted totally to his wishes and habits.

In a preferred embodiment the timer device comprises an output terminal on which after the first and the second period respectively the respective control signal is delivered, said output terminal being connected to the first setting input of a bistable circuit of which the second resetting input in connected through a reset switch to a reset voltage source, the output of said bistable circuit being coupled to the signal device and with the first input of an AND gate of which the output is connected with one of the alarm inputs of the alarm circuit of the station, the second input of the gate being connected to the output of the timer device.

Preferably a delay circuit is connected between the output of the bistable circuit and the first input of the gate. The time device comprises preferably a reset- and start-input which can be energised through the reset switch.

Furthermore the time device preferably comprises a digital display to display the lapse and/or resting part of the first and/or second period.

The timer device can also be provided with a mechanical clock which operates one or more switch contacts; when there are two such contacts which are successively operated by the clock the first is connected to an optic and/or acoustic signalling device and the second connected to the alarm input of the alarm circuit of the station.

In order that the invention may be more clearly understood, two embodiments thereof will now be described, by way of example, with reference to the accompanying drawing, in which, Figure 1 is a schematic diagram of a first embodiment according to the invention, and, Figure 2 is a schematic diagram of a second embodiment.

In Fig. 1 the reference numeral 1 denotes a surveillance station which is known in itself with a transceiver 2 and an alarm circuit 3 having a number of inputs 4a. . .4d.

The inputs 4b, 4c and 4d are connected to alarm devices which are known in themselves, for example, an alarm switch 5 to be operated by the user, a smoke detector 6 and a burglar alarm device 7.

The input 4a is connected to an output 83 of an AND-gate 8 having inputs 8r and 82.

The input 82 is connected to an output 93 of an electronic timer device 9 which is fed with current through input 9, and which has a reset- and start-input 92. The input 9, is connected with the output of a voltage source 10 which is also connected to terminal 113 of a throw-over switch 11. Terminal 11, of switch 11 is connected through a reset switch 12, which is a spring-loaded pushbutton switch, to the start- and reset-input 93 and with current supply terminal 131 of an amplifier 1 3 and with current supply terminal 14 of a bistable circuit (flip-flop) 14.The startand reset-input 92 is connected with reset input 143 of the bistable circuit 14 of which set-input 143 is connected to the output 93 of the timer circuit 9 which output is also connected with the second input 82 of the AND gate 8. Output 144 of the bistable circuit 14 is connected through a delay network comprising a resistor 1 5 and a capacitor 1 6 with the first input 8i of the AND gate 8. The terminal 112 of the switch 11 is connected to an indicator lamp 17.

The timer circuit 9 is constructed in such a way that after a predetermined period, for example 132 hours, after supplying the resetand start- signal to the input 92 a short, first, output signal occurs at the output 93 of the timer 9 while a short period, for example half an hour later, a second short output signal occurs on this same output terminal; the time which has to lapse before the occurrence of the second output signal is continuously displayed digitally on a display 18.

The output 144 of the bistable circuit 14 is connected to input 1 32 of the amplifier 1 3 of which output 1 33 is connected to the acoustical signal generator 1 9 and the optical signal generator 20.

The device operates as follows: The device is operative when the switch 11 is in the indicated position, when the bistable circuit 1 4 and the amplifier 1 3 are fed with current and voltage is supplied to the switch 1 2. When the switch 11 is in the other position the device is inoperative and the warning light 1 7 will indicate this state.

By temporarily closing the springloaded push-button switch 1 2 voltage is supplied to the start and reset input 92 of the timer 9 so that this is reset to zero and starts to operate.

After a predetermined period, for example 1 3i hours, a short output signal occurs at the output 93. The time required to elapse before the occurrence of this output signal is continuously displayed on the display 1 8. When, after a certain time period, for example after 4 hours, the switch 1 2 is closed anew, the timer 9 is reset and starts anew so that said period of 1 3 2 hours is re-started.

Closing the switch 1 2 results in voltage being supplied to the reset input 142 of the bistable circuit 14 which is thereby brought into a first stable state. In this first stable state no voltage is present at the output 144 so that there is no control voltage at the input 1 32 of the amplifier 1 3 and the acoustic signal generator 1 9 and the optical signal generator 20 are not energised.

After-the first period of 13 < hours a first output signal occurs at the output 93 which is supplied to the setting input 143 of the bistable circuit 14 which is thereby brought into a second stable state in which there is an output voltage at the output 144. The amplifier 1 3 is controlled by this voltage and the acoustical and optical signal generators 1 9 and 20 are energised indicating this state to the user at the substation.

This voltage is supplied through the delay circuit 15, 16 to the first input 8, of the AND gate 8 but, as the voltage on the output 93 has only a short duration, there is no voltage at the second input 82 at the moment at which the voltage occurs at the first input 81 so that the AND gate is not conducting; there is no output voltage at the output 83 of the AND gate 8 and the alarm circuit 3 is not energised.

When now the user closes the reset switch 1 2 for a short moment the timer device 9 as well as the bistable circuit 1 4 are reset and the whole process starts anew.

However, if during the period of a half hour after the 13Q hour periods has elapsed the reset switch 1 3 is not operated then at the end of this period a voltage again occurs at the output 93. This voltage has no influence on the bistable circuit 14 as this has already been brought in the second stable state which places a voltage on input 8, of gate 8 but as it is also supplied to the input 82 of the AND gate 8 this gate 8 begins to conduct so that an output voltage occurs at the output 83 which energises the alarm circuit 3 so that the emitter-receiver of the station is brought into the alarm state.

Fig. 2 shows the schematic diagram of an embodiment which uses a mechanical timer device which operates switches. Corresponding elements are indicated with the same reference numerals as in Fig. 1.

The embodiment according to Fig. 2 comprises a mechanical timer clock 22 with a start and reset knob 23. The timer clock 22 drives an arm 24 which cooperates with contacts 25 and 26. The arm 24 is connected with the output 111 of the switch 11, the contact 25 is connected to the input 1 33 of the amplifier 1 3 and the contact 1 6 with the alarm input 4a.

When the timer clock 22 of the timing and switching device 21 is started and the switch 11 is in the illustrated position, after a predetermined period voltage will be supplied through the switch 11,, the arm 24 and the contact 25 to the input 1 32 of the amplifier 1 3 so that the acoustical signal generator 1 9 and the optical signal generator 20 are energised. When then the reset- and start-knob 23 is pressed the timer mechanism 22 is reset and the arm 24 is brought back to its initial position after which a complete new cycle starts. When, however, the device is not reset than after a second period of, for example, a half hour voltage is supplied through the switch 111, the arm 24 and the contact 26 to the input 4a of the alarm circuit 3 which brings the emitter-receiver 2 in the alarm state.

It is clear that the combination of the arm 24 with the contacts 25 and 26 can be replaced by a suitable combination of separate switches with control elements while here, too, a continuous indication can be given of the time lapse of the first and the second period respectively, for example when the arm 24 moves along a suitable scale.

With the switch 11 in the second position the device is inoperative and this state is indicated by the lighting of the lamp 1 7.

Claims (11)

1. A surveillance system comprising a main station having an emitter and a number of substations, each substation having a transceiver coupled to an alarm circuit by means of which the state of the substations can be reported to the main station when the substations are cyclically interrogated by means of an address signal emitted by the emitter of the main station, and a resettable timer device, the interrogated substation emitting a high frequency signal modulated with a code characterising the state of the substation to the main station, and the resettable timer device after being started being operative to deliver after a predetermined first period a control signal to activate a signalling device and deliver subsequently after a second period a control signal operative to activate the alarm circuit of the substation.

2. A surveillance system as claimed in Claim 1, in which each timer device comprises an output terminal on which after the first and the second period respectively the respective control signal is delivered, the said output terminal being connected to the first setting input of a bistable circuit of which the second resetting input adapted to be connected through a reset switch to a reset voltage source, the output of said bistable circuit being coupled to the signalling device and with the first input of an AND gate of which the output is connected with one of the alarm inputs of the alarm circuit of the station, the second input of the gate being connected to the output of the timer device.

3. A surveillance system as claimed in Claim 2, comprising a delay circuit in the connection between the output of the bistable circuit and the first input of the gate.

4. A surveillance system as claimed in Claim 2 or 3, in which each timer device is provided with a reset- and start-input which can be energised through the reset switch.

5. A surveillance system as claimed in any preceding Claim in which each timer device comprises a digital display to display the lapsed and/or resting part of the first and/or the second period.

6. A surveillance system as claimed in Claim 1, in which each timer device has a mechanical clock which is adapted to operate one or more switch contacts.

7. A surveillance system as claimed in Claim 6, in which each clock operates successively two switch-contacts of which the first is connected to a signalling device and the second is connected to the alarm input of the alarm circuit of the substation.

8. A surveillance system as claimed in any preceding Claim, in which the signalling device is optical.

9. A surveillance system as claimed in any of Claims 1 to 7, in which the signalling device is acoustic.

1 0. A surveillance system as claimed in any of Claims 1 to 7, in which the signalling device is acoustic and optical.

11. A surveillance system substantially as hereinbefore described with reference to Fig.

1 or Fig. 2 of the accompanying drawing.