GB2203581A - Fire and/or burglar alarm system - Google Patents

Abstract

The system includes a timer controller IC-7, S2, S3, S4 to enable, in addition to time control of external appliances, temporary disarming of the alarm system at a preset time, eg to warn a user to disarm the alarm after waking up in the morning, and disarming automatically at the end of a period set by the user. The system also includes various time delay circuits to ensure that the alarm sounds for a preset period after initial energization, to provide a high volume alarm for a preset period followed by a lower level alarm and to provide alarm inhibit periods to allow for initial energization, arming and disarming respectively. A thermo-electric infra-red sensor and filter and amplifier circuits are provided to detect intrusion or fire. <IMAGE>

Description

TITLE: Timer Controlled Fire and Burglar Alarm System BACKGROUND OF THE INVENTION: The present invention relates to a timer controlled fire and burglar alarm system, particularly a fire and burglar alarm system incorporated with timers and ordinary battery as power source to function as fire alarm, burglar alarm, visitor detection and timer system by setting of function selector switches and to control alarm system with timers.

Generally burglar alarm system is mostly triggered by (1) direct contact or damage or (2) detector. For the first one, burglar may avoid contact and damage easily, and alarm is triggered after occurrence of damage. As for the second one, a detector usually is either on or off, it is not capable to distinguish identity of invader and thus alarm may be triggered worngly in circumstances, such as entering detection zone without turning off the system.

Furthermore, most burglar systems available in the market apply alternate current as power source, and do not function during power failure or after cutting off of power source. Moreover, since external power source is required, there is limit on place of installation and experienced burglar can evade or damage it easily.

SUMMARY OF THE INVENTION: The main objective of the present invention is to provide a practical and versatile alarm system incorporated with timers and time display for setting and disarming of alert condition at present time to meet individual requirements and to avoid wrong alarming.

Another objective of the present invention is to incorporate burglar alarm with fire alarm system by using sensor which can detect infrared ray from sudden change of room temperature, and to control other externally connected home appliance such as audio-video system, electric fan, electric cooker, electric heater, etc. by means of timer.

Another objective of the present invention is to provide a time priority circuit and time-delay circuit to control singnal detection system by a timer so that generation of music is prior to alarm, and detection function can be discharged temporarily to avoid wrong alarming.

Another objective of the present invention is to provide an alarm system with ordinary battery as power - source so that it can be installed at any place to prevent from evasion or damage.

BRIEF DESCRIPTION OF THE DRAWING: Fig. 1 is a circuit diagram for a preferred embodiment according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT: The clock controlled fire and burglar alarm system according to the present invention has a drive control which mainly composed of a function selector switch S1 to set driving mode, and uses a thermo-electric infrared sensor to give driving singnal. Control sequence and circuit of a preferred embodiment are described below with reference to the attached drawing.

(A) Singnal Sensor and Detection: The present invention uses a thermo-electric infrared sensor to detect invasion of person into, or fire at its scope of detection by infrared ray from human body or infrared ray from sudden rising of room temperature which is converged to the sensor by means of reflector or converging lens. The sensor then transforms change of infrared energy to change of potential energy, which is sent to positive terminal of ICla for amplification and filtering, and to C1 for filtering out noise. ICla, resistors R1, R2 and R3, and capacitors C2, C3 and C4 compose a nonreversible a.c. amplifier to cut off unnecessary frequency but amplify frequency required. The amplified signal is then sent to negative terminal of IClb via C5 and R5 for amplification and filtering. IClb, resistors R5, R6.R7 and R4, and capacitors C5, C7 and C8 compose a reversible a.c. amplifier to cut off unnecessary frequency but amplify frequency required.

R6 is a semi-variable resistor to adjust amplification factor of IClb. Amplified and filtered signal from IClb is sent to an amplitude limited comparator composed of IClc, ICld, and resistors R8, R9, R10 and R11 for comparation to deter mine whether the signal input is within or beyond range of standard potential. If signal input has a potential lower than the standard potential at negative terminal of IClc, output of ICic is low. If signal input has a potential higher than the standard potential at negative terminal of IClc, output of ICic turns to High. Change of potential at output from ICld is contrary to that of IClc.Therefore, if input potential is higher than either that at negative terminal of ICic or positive terminal of ICld, the transistor TR1 is triggered and grounded.

(B) Sound Power Amplification and Driving: Whenever output of the aforesaid amplitude limited comparator is beyond the standard potential and trigger the transistor TR1, and if TR1 is grounded, potential of resistor R16 truns from High to Low, pin "IN" of IC8 turns to Low too. If clearing terminal "C1" of IC-8 is Hight, pin "T2' of IC-8 is Low. Thus, capacitors C10 and Cli discharge through pin "T2", and simultaneously "Output" terminal of IC-8 gives a High output through resistor R19. diode D2 to base of transistor TR3 so that TR3 is turned on and grounded. Then, negative potential via TR3, resistor R53 to base of PNP transistor TR4 to turn on TR4, and thus positive potential goes to voltage regulator IC5 and sound amplifier IC6 via TR4.

(C) Two Driving Modes Function selector switches Sla and Slb are of three step switches. The upper step is for normal function (visitor detection), the middle step is for turning off power, and the lower step is for alert condition.

When the switch is at the upper step, i.e., normal function condition, negative potential is connecting to the base of PNP transistor TR8 via resistor 43 so that TR8 is switched on by a bias. Then, after stablization by voltage regulator IC5, positive current is passing through TR8, and then, after dividing by resistors R42 and P.41, powers a music IC4 which hence gives a music signal output to viriable resistor VR1 via diode D10 and resistor R40. The variable resistor VR1 is for volume adjustment. The music signal is then sent to a sound power amplifier IC6 for amplification to drive a speaker for giving of audiable music.

When the switch is at the lower step, i.e., alert condition, PNP transistor TR8 can't be switched on because there is no bias to its base, and thus the music IC4 will not function because of lack of power. Since the base of NPN transistor TR7 is not grounded, positive current after stabilization at voltage regulator IC5 is connecting to base of TR7 via resistor R44, and TR7 is thus switched on by a bias, and then the positive current is connecting to a alarm generator circuit composed of IC3a, IC3b and IC3d.

(D) Alarm Generation: IC3a and resistors R21, R22, R23 and R24 as well as capacitor C15 compose a square wave generator. Square wave so generated charges capacitor C16 via resistor R25 and after rectification at a diode D8.

IC3b, resistors R26, R27, R28, R29, R30 and R31, and capacitor C17 compose an audiable signal generator, frequency of audiable signal generated by it can be altered by change of potential. Because potential of C16 can be lowered by discharging via resistor R27, audible signal from IC3b can have its frequency changed like alarm given by policy car. The signal is then sent to sound power amplifier IC6 via capacitor Cl9 and resistor R36 for amplification to drive the speaker for giving an alarm.

(E) Multiple Timing Setting and Time Priority Circuit: The present invention is mainly characterized by a multiple timing setting and time priority circuit. The time control circuit comprises timers with including an analog/digital output type IC-7 a time display (LCD) and setting switches S2, S3 and S4 for time setting.

The first timer CH-i is for timing control on externally connected electric appliance, the second timer CH-2 is for setting at any time to disarming alert condition and for setting a time priority function to change alarm signal to music alarm, and the third timer is to disarm alert condition at any time without setting time priority function to prevent from wrong alarm. With the third timer, user can preset a time, such as the scheduled time of returning, to disarm the alert condition.

When the second timer (CH-2) reaches the preset time of disarming alert condition, output terminal of CH-2 gives a High signal to diodes D3, D4 and D6. High signal passing through D4 reaches base of NPN transistor TR2 via resistor R47 to switch on and ground TR2. Thus, clearing terminal "C1" of IC-8 is grounded so that IC-8 is cleared and gives no output, the detection function is hence discharged.

High signal passing through D3 goes to base of NPN transistor TR3 via resistor R52 to switch on and ground TR3.

Then, negative potential is connecting to base of PNP transistor TR4 via TR3 and resistor R53 to switch own TR4, hence positive current is going to IC5 and IC6 via TR4.

High signal passing through D6 goes to base of NPN transistor TR4 via resistor R45 to switch on and ground TR9 so that negative potential is connecting to base of PNP transistor TR8 via TR9 and resistor R43 to switch on TR8.

Then, the aforesaid positive current via TR4 and IC5 reaches resistors R42 and R39 via TR8. Positive current passing through resistor R42 reaches 1C4 and cause IC4 to generate music signal, which is then sent to IC6 for amplification and then to drive the speaker for giving of music. Positive current passing through resistor R39 reaches base of NPN transistor TR5 to switch on and ground TR5, and thus alarm output resistor R36 is grounded to prevent from generation of alarm signal.

With the above design, in spite of position of function selector switches Sla and Slb, generation of music is a pr iority and alert function is disarmed if output signal from CH-2 is high. Therefore, this timer can be used to control signal detection system for disarming alert function temporarily in order to ease user to turn off alarm at any time such as after waking up in morning.

When the third timer reaches the preset time for disarming of alert condition, output terminal of CH-3 gives a High signal to diode D5 and then base of NPN transistor TR2 via resistor R47 to switch on and ground TR2. Hence, clearing terminal "C1" of IC-8 is grounded, IC-8 is thus cleared and will not give any output, the detection function is discharged.

(F) Time-delay Circuit: Time-delay circuit is designed to continue generation of sound/alarm for a certain period of time after leaving of the detected person from the scope of detection even he stays in the scope of detection for only a very short time.

The sensor will not receive infrared after the detected person left the scope of detection, and thus ICla and IClb do not give signal, output from comparators ICic and ICld becomes low, transistor TR1 becomes open because there is no bias to it, positive potential is connecting to input pin "IN" of IC-8 via resistors R14 and R16 so that potential at input pin "IN" turns from Low to High. If clearing terminal "C1" of IC-8 is High, terminal "T2" of IC-8 turns from discharging condition to potential comparison condition.

As capacitors C10 and Cii have been discharged, their poten tial is lower than the standard potential in IC-8 so that output terminal "OUT" of IC-8 remains High to switch on TR3 and TR4, positive current continues to flow to ICS and IC6, generation of audible signal continues.

Because resistor R15 charges C10 and Cull, potential of C10 and Cii becomes higher and higher. When potential of Cl0 and Cii becomes higher than the standard potential in IC-8, output terminal "OUT" of IC-8 truns from High to Low, TR3 and TR4 become open, generation of audible signal stops.

Therefore, change of resistance of resistor R15 or capacitance of capacitors Cl0 and Cii can change the delaytime. The time-delay circuit according to the present in-.

vention is characterized by two different lengths of delay time. Only C10 functions at normal condition and thus delay time is short because it is not necessary to generate audible signal for a long time at normal condition. At alert condition, because the negative terminal of capacitor Cii is grounded by setting the switch Slb at lower step, Cii and Cl0 are of parallel connection, capacitance is enlarged, and thus delay time is extended, alarm can continue for a long period of time.

In order to prevent from wrong alarming, volume of alarm can be divided into two stages. Length of the first stage can be set as 0-30 seconds at discretion, and volume at the first stage can be set by a variable resistor VR2.

When the alarm curcuit is powered via TR7, capacitor Cl8 is charged by positive current via R32. If potential at negative terminal of IC3d is lower than the standard potential at its positive terminal, output of IC3d is High so that potential is connecting to base of NPN transistor TR6 via resistor R38 and after filtering at C20, TR6 is switched on by a bias and grounded, then negative terminal of variable resistor VR2 is grounded, output potential of alarm is lowered and thus volume of alarm is reduced.

Potential of C18 becomes higher and higher by the charging, potential at negative terminal IC3d gets higher and higher too. If potential at negative terminal of IC3d becomes higher than the standard potential at its positive terminal, output of IC3d is low so that TR6 can't be switched on and grounded, volume of alarm is thus not reduced but output is given at full volume. Therefore, period for the first stage is adjustable by adjusting variable resistor VR3 to change standard potential at positive terminal of IC3d.

The circuits and sensor in the present invention might be unstable during the initial period after connecting to power source. Therefore, a delay circuit is designed to delay starting of its function for about 2 minutes after connecting to power source in order to prevent from wrong detection and to permit user to have a sufficient time to leave scope of detection. The said delay circuit is composed of clearing terminal "C1" of IC-8 and capacitor C13.

Whenever the clearing terminal "C1" of IC-8 is High, no clearing will occur. When the clearing terminal "C1" of IC-8 is Low, IC-8 is cleared, no output appears at output terminal "OUT" of IC-8, and such output terminal "OUT is Low. Terminal "T2" charges capacitors C10 and Cii rapidly, IC-8 is cleared and has no output. Before connecting to power source, residual charge in capacitor C13 discharges through diode D1. As soon as the present invention is turned on, capacitor C13 is charged by current via voltage regulator IC2 and resistor R46. Potential in capacitor C13 is low during the initial period of charging, clearing terminal "C1" of IC-8 maintains Low and is still cleared.

After charging for a certain period of time, capacitor C18 is fully charged, clearing terminal "C1" of IC-8 turns to High potential, no clearing is occurred, and present invention is ready.

In addition to the aforesaid features and functions, the present invention has an "EXT" socket for connection of auxiliary device such as automatic dialling system, radio system, lighting system or other security facilities. Furthermore, length of fire and burglar detection period can be set with its timers. It is indeed an economic, convenient and versatile fire and burglar alarm system.

Claims (5)

CLAIMS:

1. A timer controlled fire and burglar alarm system characterized by using of a plurality of time priority circuits, time-delay circuit, timer controlled alarm setting circuits and timers with electronic display for setting and disarming of alarm condition and/or driving or peripheral device by timers.

2. A timer controlled fire and burglar alarm system as claimed in Claim 1 wherein the timer controlled alarm setting circuit can divide volume of alarm into two stages; volume of alarm at the first stage is adjustable by adjustment of a variable resistor VR2 which can lower alarm output potential by grounding of its negative terminal when a transistor TR6 is switched on by a bias and grounded; volume of alarm at the second stage is at maximum as after fully charging of a capacitor C18 can switch off the aforesaid grounded transistor so that potential to sound factor amplified is not lowered; and length of period for the first stage is determined by a variable resistor VR3 which changes standard potential of an IC which in turn change charging efficiency to capacitor C18.

3. A timer controlled fire and burglar alarm system as claimed in Claim 1 wherein the time-delay circuit is characterized by availability of two different lengths of time delay in a manner that only a capacitor C10 functions at normal condition so that period of sound generation is short, and two capacitors C10 and Cli are in parallel connection by grounding of negative terminal of capacitor Cli upon setting a function selector switch to alert condition so that capacitance is increased and period of sound generation is long.

4. A timer controlled fire and burglar alarm system as claimed in Claim 1 wherein the timers include an analog/ digital output type integrated circuit and a time display, the first timer is for controlling externally connected electric appliance, the second timer is for setting a time to disarm alert condition with time priority function to change audible alarm to music, and the third timer is for disarming alert condition at any time.

5. A timer controlled fire and burglar alarm system as claimed in Claim I wherein the time priority circuit is characterized by the following: when the second timer (CH-2) reaches the preset time of disarming alert condition, output terminal of CH-2 gives a High signal to diodes D3, D4 and D6, high signal passing through D4 reaches base of NPN transistor TR2 via resistor R47 to switch on and ground TR2 so that clearing terminal "C1" of IC-8 is grounded, IC-8 is cleared and gives no output, the detection function is hence discharged; high signal passing through D3 goes to base of NPN transistor TR3 via resistor R52 to switch on and ground TR3, so that, negative potential is connecting to base of PNP transistor TR4 via TR3 and resistor R53 to switch on TR4, positive current is going to IC5 and IC6 via TR4; high signal passing through D6 goes to base of NPN transistor TR4 via resistor R45 to switch on and ground TR9 so that negative potential is connecting to base of PNP transistor TR8 via TR9 and resistor R43 to switch on TR8, the aforesaid positive current via TR4 and IC5 reaches resistors R42 and R39 via TR8, positive current passing through resistor R42 reaches IC4 and causes IC4 to generate music signal, which is then sent to IC6 for amplification and then to drive the speaker for giving of music; positive current passing through resistor R39 reaches base of NPN transistor TR5 to switch on and ground TR5 so that alarm output resistor R36 is grounded to prevent from generation of alarm signal; and when the third timer reaches the preset time for disarming of alert condition, output terminal.of CH-3 gives a high signal to diode D5 and then base of NPN transistor TR2 via resistor R47 to switch on and ground TR2 so that clearing terminal "Cl" of IC-8 is grounded, IC-8 is thus cleared and will not give any output, the detection function is discharged.