AU702175B2 - A monitoring system - Google Patents

Description

THIS INVENTION relates to a trigger circuit and camera for causing multiple operation of the camera. In particular, the invention concerns a trigger circuit for operation of a camera to cause the camera to take multiple pictures. The invention will be described by way of example with reference to the camera being employed for security monitoring purposes. It should be appreciated that the apparatus of the invention may also be used for other purposes.

United States patent specification 5155474 discloses an intrusion detection apparatus for detecting the presence of an intruder. The apparatus 10 includes a motion sensor, a still camera and a control circuit for triggering the camera so that a single still picture is taken. The apparatus employs an infrared sensor and includes lights which automatically illuminate the intruder so that a good quality picture may be produced. The camera is concealed within *the apparatus and shutter noise is disguised so that the intruder is convinced that the apparatus is a conventional light and sound signal intrusion detector.

The picture produced by such an apparatus is often inadequate.

Also, when the intruder is illuminated and the alarm sounds, he may quickly exit the scene without the camera being able to secure a good picture for subsequent use in identifying the intruder.

S 20 It is an object of the present invention to provide a trigger circuit •and camera which at least minimises the disadvantage referred to above.

According to one aspect, the invention provides a trigger circuit and still camera, the trigger circuit including a sensor module for detecting li movement, a trigger module receiving an output from the sensor module for Ollll= providing a control signal for the camera for controlling the camera so that the camera takes multiple pictures in response to a single said sensor module output.

It is preferred that the control signal controls the camera so that it takes three pictures although a greater number is an included option.

The trigger circuit may include an indication circuit which provides an indication that the trigger circuit has operated to cause the camera to take pictures. The indication circuit may provide a visual indication of such operation and may include a latch which together with an enabling circuit activated by a disarming facility enables the indication of photographs being taken. The latch is reset by a power switch.

The trigger circuit may be constructed to allow it to be remotely actuated and to remotely arm or disarm the indicator circuit mentioned above.

Preferably, a transmitter and a receiver are included with the trigger circuit for this purpose. A two channel transmitter and receiver are preferred. Both channels need not be used.

The sensor may sense or detect motion. The sensor may consist of an infrared motion detector. Alternatively, the sensor includes a sensor module having an infrared sensor and a microwave motion sensor and the response from both of these may be used such that if both sensors provide an S• :output of a sufficient magnitude, then the trigger circuit functions to operate the camera.

The trigger circuit may include a monostable for providing a timing *.*.*pulse and for controlling an oscillator which provides multiple output pulses for S: controlling the camera. A driver may be interposed between the oscillator and the camera.

*If desired infrared film may be used in the camera although if ambient light conditions permit standard photographic film with a suitable speed rating may be used.

The camera preferably uses either high speed or infra red film. In this way, there is no need for illuminating the intruder to allow acceptable quality pictures to be produced.

A particular preferred embodiment of the invention will now be described by way of example with reference to the drawings in which: Figure 1 is a block diagram of a trigger circuit and camera according to an embodiment of the invention; Figure 2 is a block diagram of a camera and a trigger module which forms part of the circuit of the invention; Figure 3 is a block diagram like that of Figure 2 but showing further detail; Figure 4 is a detailed circuit diagram of a trigger module according to an embodiment of the invention.

The figures do not illustrate detail of a two channel transmitter and receiver which may be used with the trigger circuit of the invention. A UHF transmitter/ receiver of known design may be used. The transmitter/receiver function provides two outputs. The state of one of these two outputs determines whether the power is applied to the trigger circuit thereby arming the system.

This output state also enables the photo taken latch and the arm/disarm indicator. The second of the two outputs is unused.

Figure 1 of the drawings shows a block diagram of a trigger circuit and camera. A hand held two channel transmitter 20 is used to operate the circuit and activate a solid state switching circuit for initiating the supply of power to the circuits and for enabling/disabling the indication circuit. The transmitter has two control buttons, one for each channel for transmitting encoded signals when pressed. these signals are received in receiver 21 and decoded and selectively toggle an arm/disarm latch in the UHF received (which includes LED1 :shown in Figure 3) for activation to provide an indication that an intruder has been detected.

*The user operates the transmitter to ensure power is supplied to the circuit and then arms the indication circuit when he is sufficiently far away 'from the sensor module 23. Power is supplied by power supply 24. The module 22 functions to provide a plurality of trigger pulses to the camera 25. The camera is a still camera and is operated to produce a plurality of still pictures once an intruder is detected. Where the camera is intended to operate in low light conditions, film of a suitable speed for those conditions is employed.

Alternatively, infra red film may be used in the camera.

The pulses from module 22 may directly trigger an electronic shutter mechanism in the camera or may be employed to operate a solenoid to depress the shutter button. Since the camera is unattended it should have autowinding capabilities. LED2 provides an arm/disarm display. LED1 indicates the detection of an intruder. Switch 27 is representative of a power switch.

The sensor module preferably contains both an infrared motion sensor and a microwave motion detector combined into a single unit which detects a doppler shift in reflecting a microwave signal and adds this response to the output from the infrared sensor. If the response from both sensors is of a sufficient magnitude to indicate movement and a sizeable warm body a contact is opened to indicate an alarm condition. This triggers the trigger module.

Figure 2 shows greater detail of the camera and trigger module.

The trigger module 22 of Figure 1 includes a buffer 30 which receives the signal from the sensor. The buffer 30 is coupled to a monostable 31 which produces a pulse of a predetermined duration. In one example, this pulse has a duration of 3 seconds and controls the operation of astable 32 to cause the a stable to :provide a plurality of output pulses. A biasing network 33 extends between monostable 31 and astable 32.

The output from astable 32 is coupled to the camera 25 via a driver o 34 to control multiple operation of the shutter in the camera so that multiple pictures are taken.

S* Figure 3 shows further detail of the block diagram shown in Figure 2. The output from astable 32 is applied to a latch 40 to set the latch. This allows the indicator LED1 to indicate that an intruder has been detected and is only illuminated when a remote disarm signal is received from the UHF receiver 21.

The receiver also controls switch Q4 when a disarming signal is received from the receiver 21 switch Q4 closes to indicate that the system has been disarmed and LED2 is then illuminated.

Figure 4 shows a detailed circuit diagram of a trigger module and sensor circuit of the invention. When an intruder is detected, the contact SENS moves to the position shown from a position where it is closed to connect earth potential to the base of transistor Q2 (in that position with earth coupled to the base, the transistor is in its off or non-conducting state). Transistor Q2 then provides a negative going step which is differentiated by resistor R1 and capacitor C1, thus providing a negative going trigger pulse for the monostable IC. The monostable is controlled by its associate circuit components to provide a 3 second output pulse. This pulse is coupled via diode D2 to astable IC2 to enable the astable. The circuit components associated with astable IC2 ensure that the output pulses produced by the astable have a period of 0.7s and thus three output pulses are produced before the output of monostable IC1 goes low.

If the output of IC1 should go low before the negative going transition of the output from IC2 then this output is coupled back to pin 4 of IC2 via diode D3 to ensure that IC2 remains enabled until completion of the mark period of 0.7s.

The biasing network, consisting of resistors R9, R10 and R 1, maintains a bias voltage of 4 volts, on capacitors C2 and C4 via diodes D7 and D6 respectively. This ensures the same initial voltage is maintained on the timing capacitors for IC2 regardless of whether the astable has produced the first or subsequent pulses.

The output from IC2 at pin 3 is applied to transistor Q1 which is an inverting output driver for enabling the output from IC2 to drive a camera shutter "solenoid.

o Silicon controlled rectifier SCR1 and its associated circuitry form an indication circuit which provides a latch and, when triggered by IC2 and "°.enabled by disarming the unit, latches light emitting diode LED1 on until reset by removal of power. LED1 indicates that the circuit has been activated by the presence of an intruder.

Three (optional) consecutive activations of the camera for each time that the sensor is activated ensures that three (optional) photographs will be taken. Should the intruder continue to activate the sensor by moving in its field of detection, consecutive groups of three photographs will continue to be taken until the intruder leaves or the film in the camera is exhausted.

Thus with the invention, by multiple triggering of the camera the chance of securing a useful photograph of the intruder is enhanced.

Power is supplied to connector S7. Switch S3 supplies the input power via a reverse polarity protection diode D9 to the emitter of transistor the emitter of transistor Q4 and to the cathode of zener diode Z1 via resistor R23.

Connector S8 supplies input power to the UHF receiver 21.

The receiver 21 provides a high level and a low level output.

When this output at connector S5 is low transistor Q4 is on. With Q4 on 12VDC is applied to the voltage regulator Q3 and 3VDC is applied to the batteries in the camera via connector S1 only if the battery voltage is less than 3VDC. When Q4 is on transistor Q5 is off and LED2 (the arm/disarm indicator) is off to indicate that the circuit is armed. The collector of Q5 is connected to resistor R14 via connector S6.

Zener diode Z1 is off when Q4 is conducting. The emitter of Q4 is connected to the anode of SCR1 via resistor R24.

If an intruder is detected the output from IC2 not only switches Q1 to operate the camera but also provides a gate signal to SCR1 to cause SCR1 to conduct. SCR1 is held conducting by the positive voltage at connector S9.

Diode LED1 remains off since Q5 is off.

:When the receiver is disarmed (the power enable signal at connector S5 goes high), the power to IC1 and IC2 is discontinued since the 12VDC is no longer available at the collector of Q4 when a high signal at the base of Q4 turns that transistor off. Q5 is then conducting and the LED5 is illuminated to indicate that the system has been disarmed. When the collector of goes high, LED1 is forward biased and if the SCR1 is still latched because an intruder was detected, LED1 is then illuminated.

If the receiver receives an "arm" command a low signal to the base of Q4 arms the system for a further operation.

8 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A trigger circuit and still camera for a monitoring system, the circuit including a sensor module for detecting movement, a trigger module receiving an output from the sensor module for providing a control signal for the camera for controlling the camera so that the camera takes multiple pictures in response to a single said sensor module output.

2. The trigger circuit and camera of claim 1, wherein the camera takes three pictures in response to a single said sensor module 10 output.

3. The trigger circuit and camera of claim 1 or 2 including a latch, :0soan enabling circuit for arming and disarming the trigger module and an indicator for indicating that a photograph has been taken, whereby the photograph indicator is operative to indicate that a photograph has been taken when the enabling circuit is operated to disarm the trigger module.

4. The trigger circuit and camera of claim 3 wherein the latch includes a silicon controlled rectifier (SCR) and the photograph indicator is in series with the SCR.

S 20 5. The trigger circuit and camera of claim 4 wherein the SCR is latched and unlatched by the enabling circuit.

6. The trigger circuit and camera of claim 3, 4 or 5 including an arm/disarm indicator coupled to the enabling circuit for Il. indicating whether the trigger circuit is armed or disarmed.

7. The trigger circuit and camera of claim 6 wherein the indicators are light emitting diodes.

8. The trigger circuit and camera of any one of claims 1 to 7 wherein the trigger module includes a buffer for receiving the output from the sensor module, a monostable coupled to the buffer, an astable oscillator driven by the monostable and a driver coupled to the astable oscillator for providing an output for controlling the camera.

Claims (4)

1. 9. The trigger circuit and camera of any one of claims 1 to 8 wherein infra red film is employed in the camera. The trigger circuit and camera of claim 3 including a transmitter providing for arming and disarming control signals, a receiver responsive to the transmitter for controlling the enabling circuit for arming and disarming the trigger module.
2. 11. The trigger circuit and camera of claim 10 wherein the transmitter and receiver operate in the UHF band.
3. 12. The trigger circuit and camera of any one of claims 1 to 11 wherein the sensor module includes an infrared motion detector and a microwave motion sensor.
4. 13. A trigger circuit and camera substantially as herein described with reference to the drawings. DATED this 3 day of February 1998 WALTER MEYER By his Patent Attorneys CULLEN CO. ABSTRACT A trigger circuit and camera is disclosed for a monitoring system. A UHF transmitter is included for arming and disarming the trigger circuit. A UHF receiver provides arming and disarming signals for a trigger module and a sensor module allows the trigger module to provide an output for operating a camera for producing multiple pictures in response to one activation of the trigger module by the sensor module. *S* e* S. ft f f