RU2168767C1 - Smoke signaling device - Google Patents

Abstract

FIELD: automatic fire signaling systems. SUBSTANCE: in first variant of invention smoke signaling device includes receiving chamber with additional reflecting member; modulator with additional output and additional circuit having connected in series analog-to-digital converter, parallel register, digital-to-analog converter and adder. In second variant of invention smoke signaling device includes receiving chamber with additional reflecting member; modulator with additional output and two additional circuits. One of said circuits includes connected in series: analog-to-digital converter, first parallel register, first digital-to-analog converter, divider with limiting unit, multiplier and adder. Second circuit includes controlled switch, second parallel register and second digital-to-analog converter. Device prevents false operations caused by increased reflection from inner surface of receiving chamber when there is no smoke and eliminates conditions of non-operations when there is limit concentration of smoke in receiving chamber caused by deteriorated properties of optical system. EFFECT: enhanced reliability of smoke signaling device. 2 cl, 5 dwg

Description

 The invention relates to an automatic fire alarm.

 Smoke detectors are known that contain a receiving air intake chamber with an emitter and a photodetector located in it, as well as a modulator connected to the emitter input, an amplifier connected to the photodetector, and an input relay (see F. Sharovar, Fire Alarm Devices and Systems.- M .: Stroyizdat, 1979, p. 28-34).

 The disadvantages of these detectors include the presence of false alarms due to an increase in reflection from the inner surface of the chamber when, for example, dust, dew or corrosion appears on it, which in turn leads to false alarms of the detector.

 Also known is the "Smoke detector" (see description to a.c. N 955143, class G 08 B 17/10, publ. In 1982), which is selected as a prototype.

 Known smoke detector contains a receiving chamber, in which a radiator and a photodetector are located, the output of which is connected to an amplifier, a modulator, the output of which is connected to an emitter and a synchronizing input of the amplifier, an integrator, an amplitude detector, a separation element, an amplifier-detector, an element And, two threshold elements , optional integrator and output relay.

 The disadvantage of this detector is the absence of triggering when there is a maximum concentration of smoke in the receiving chamber due to the deterioration of the properties of the optical system.

 The objective of the invention is to create a smoke detector with high reliability by eliminating false alarms when increasing reflections from the inner surface of the receiving chamber in the absence of smoke and eliminating cases of the absence of the detector in the presence of a limiting concentration of smoke in the receiving chamber due to deterioration of the properties of the optical system.

 The problem is achieved in that in a smoke detector containing a receiving chamber with a transmitter and a photodetector located at an angle to each other, a modulator, amplifier, threshold element and output relay, while the input of the emitter is connected to the output of the modulator, and the output of the photodetector is connected to the input of the amplifier, the receiving chamber is additionally equipped with a reflective element that causes the signal to appear on the photodetector in the absence of smoke, and the modulator has an additional output, the signal from which is fed to the synchronizing the analog-to-digital converter stroke and the parallel register clock input at the moment the detector starts operating, the analog-digital converter data input is connected to the amplifier output, which is also connected to one of the inputs of the threshold element, the analog-digital converter output is connected to the clock register parallel input, in series connected to a digital-to-analog converter and a summing element, the output of which is connected to another input of the threshold element, the second input of the summing element is an input for supplying an initial threshold voltage of the threshold element is connected to the output of the output relay, the output of which is an output device.

 The task is also achieved by the fact that in a smoke detector containing a receiving chamber with an emitter and a photodetector located at an angle to each other, a modulator, amplifier, threshold element and output relay, while the emitter input is connected to the modulator output, and the photodetector output is connected to the input of the amplifier, the receiving chamber is additionally equipped with a reflecting element that causes the signal to appear on the photodetector in the absence of smoke, and the modulator has an additional output, the signal from which is fed to the synchronizer the input input of the analog-to-digital converter, the clock input of the first parallel register and to the input of the controlled key at the moment the detector starts working, while the analog-to-digital converter is connected in series with the first parallel register, the first digital-to-analog converter, the divider with restriction, the multiplier and the summing element, the output which is connected to one of the inputs of the threshold element, the other input of which is combined with another input of the analog-to-digital converter and connected to the output of the amplifier, the output of the controlled key through the second parallel register, the second digital-to-analog converter is connected to the second input of the divider with restriction, the second input of the second parallel register is connected to the output of the analog-to-digital converter, the other input of the summing element is connected to the output of the first digital-to-analog converter, the output of the threshold element is connected to the output relay the output of which is the output of the device, the second input of the multiplier is the input of the initial threshold voltage.

New in the invention is:
- the presence in the receiving chamber of a reflective element, causing the appearance of a signal on the photodetector in the absence of smoke;
- the presence of an additional output from the modulator, the signal on which appears at the time the emitter starts operation;
- the introduction in the first embodiment of a chain of series-connected analog-to-digital converter (ADC), a parallel register, a digital-to-analog converter (DAC) and a summing element, while the signal from the additional input of the modulator is fed to the synchronizing input of the ADC and the clock input of the parallel register, and the second input The ADC is connected to the amplifier output.

 - the introduction in the second embodiment of one chain of series-connected ADCs, the first parallel register, the first DAC, the divider with restriction, the multiplier and the summing element and another chain of the managed key, the second parallel register and the second DAC, while the signal from the additional output of the modulator is applied to the ADC synchronizing input, the clock input of the first parallel register and the input of the controlled key, the second ADC input is connected to the output of the amplifier.

In the proposed detector, in comparison with the prototype, the state of the receiving chamber is constantly monitored and this state is evaluated by:
- a constantly present signal from a reflecting element in the absence of smoke that is specially emitted at the output of the photodetector;
- determining and storing the magnitude of the signal at the output of the photodetector at the time the detector starts operation using the signal generated at the output of the modulator;
- comparing the signal at the output of the photodetector with the signal measured at the time the detector started working.

 Thus, constant monitoring, evaluation of the detector's receiving chamber and auto-tuning significantly increase the reliability of its operation.

The invention is illustrated by drawings, where:
in FIG. 1 is a structural diagram of a smoke detector (option I);
in FIG. 2 is a structural diagram of a smoke detector (option II);
in FIG. 3 - amplitude-time diagrams explaining the operation of the detector;
in FIG. 4 shows a top view of the receiving chamber with the cover removed;
in FIG. 5 is an example implementation of a modulator.

 The smoke detector (Fig. 1) contains an emitter 1 and a photodetector 2 located at an angle to each other in the receiving chamber 3, a modulator 4, an amplifier 5, a threshold element 6, an output relay 7, an ADC 8, a parallel register 9, a DAC 10, summing up element 11.

 The smoke detector (Fig. 2) contains an emitter 1 and a photodetector 2 located at an angle to each other in the receiving chamber 3, a modulator 4, an amplifier 5, a threshold element 6, an output relay 7, ADC 8, the first parallel register 9, DAC 10, a summing element 11, a controlled key 12, a second parallel register 13, a second DAC 14, a divider with a limit of 15, a multiplier 16.

The diagrams in FIG. 3 characterize:
a - pulses at the main output of the modulator 4;
b - pulses at the additional output of the modulator 4;
in - pulses at the output of the amplifier 5;
g is the signal at the output of the threshold element 6.

The symbols on the diagrams indicate:
t ₀ is the moment of switching on of the modulator 4;
t ₁ - the moment of the end of the pulses at the additional output of the modulator 4;
t ₂ - the moment of appearance in the receiving chamber 3 of smoke with a concentration below the threshold;
t ₃ - the moment of appearance in the receiving chamber 3 of smoke with a concentration above the threshold.

 The receiving chamber 3 (Fig. 4) contains a reflecting element 17, made, for example, in the form of a cylinder of the same material as the receiving chamber itself.

The emitter 1 and the photodetector 2 (Fig. 1) are placed at an angle to each other in the receiving chamber 3. The input of the emitter 1 is connected to the output of the modulator 4, and the output of the photodetector 2 is connected to an amplifier 5 connected in series with the threshold element 6 and the output relay 7, the output of which is the output of the detector. An additional output of the modulator 4 is connected to the clock input of the ADC 8 and the clock input of the parallel register 9 connected in series with the summing element 11, the second input of which is the input of the initial threshold voltage U _on , and the output of the summing element 11 is connected to the second input of the threshold element 6. Second input ADC 8 is connected to the output of amplifier 5.

The emitter 1 and the photodetector 2 (Fig. 2) are placed at an angle to each other in the receiving chamber 3. The input of the emitter 1 is connected to the output of the modulator 4. The output of the photodetector 2 is connected to the input of the amplifier 5, connected in series with the threshold element 6 and the output relay 7, the output of which is the output of the detector. An additional output of the modulator 4 is connected to the synchronizing input of the ADC 8, the clock input of the first parallel register 9 and the output of the managed key 12, connected in series with the second parallel register 13 and the second DAC 14. The second input of the second parallel register 13 is connected with the output of the ADC 8, connected in series with the first parallel register 9, the first DAC 10, the divider with a restriction of 15, the multiplier 16 and the summing element 11, the output of which is connected to another input of the threshold element 6. The second input of the ADC 8 is connected with the output of amplifier 5. The second input of the summing element 11 is connected to the output of the first DAC 10, and the output of the second DAC 14 is connected to the second input of the divider with a limit of 15. The second input of the multiplier 16 is an input for supplying an initial threshold voltage U _on .

 Modulator 4 with an additional output can be performed (see Fig. 5), for example, on a chip type K561TL1 - valves D1-D4, a chip K561LE5 - valves D5, D6 and a chip K561IE11 - binary counter D7.

The valve D1, the resistor R1 and the capacitor C1, when the supply voltage E _{p is} turned on, form a single pulse, which sets the outputs of the binary counter D7 to zero. The gate D3, the resistor R2 and the capacitor C2 form a square-wave generator with a duty cycle of 2, used as a clock for the binary counter D7. The binary counter D7 counts the pulses at the output of the valve D3. After the fourth pulse arrives at its clock input, a logic unit signal appears at the output of Q2, which stops the counter through the PI input. Valve D4, resistor R3, and capacitor C3 convert the pulses of the generator into rectangular pulses with a duty cycle of about 10,000; valve D5 inverts these pulses and creates a pulse sequence with a duty cycle of about 10,000 shown in FIG. 3a and used to control the current of LED 1 (emitter 1) using transistors of the KT3107I and KT816G type.

 At the same time, valve D6 also inverts the pulses from output D4. When a logical unit signal of pulses passing through gate D6 appears at the output Q2, it stops as a result of which, after turning on the power, a sequence of pulses of limited duration (see Fig. 3b) is formed, which is used to control the gated ADC 8, parallel to register 9 and through the managed key 12 parallel register 13.

 Amplifier 5 can be implemented, for example, based on operational amplifiers K1407YD2.

 The gated analog-to-digital converter 8 can be performed, for example, on microchips of the K1401CA1 comparator of controlled keys of the type K561KT3, a binary counter K561IE11 and a resistive matrix of the type R-2R.

 As a controlled key 12 and parallel registers 9 and 13, for example, microcircuits of the type K561KT3 and K561TK3, respectively, can be used.

 Digital-to-analog converters 10 and 14 can be implemented, for example, on resistive matrices of type R - 2R.

 The threshold device 6 can be performed, for example, on biopolar transistors of the type KT3102BM and KT3107I.

 The output relay 7 can be implemented, for example, on biopolar transistors of the type KT3102BM.

 The summation of the signals in the summing element 11 can be carried out, for example, on resistors.

 A divider with a limit of 15 and a multiplier 16 can be performed, for example, on type K561 microcircuits.

 The smoke detector (Fig. 1) works as follows.

 The modulator 4, operating in a self-oscillating mode, for example, with a frequency f = 1 Hz and a duty cycle of the output pulses S = 10000 (Fig. 3a), controls the operation of the emitter 1 installed with the photodetector 2 in the receiving chamber 3 at an angle to each other. Therefore, direct radiation from the emitter 1 does not get to the photodetector 2, and at its output in the absence of smoke, a signal reflected from the reflecting element 17 will appear.

After the modulator 4 is turned on, at its additional output for a certain time, for example 0.5 s, a signal is generated (Fig. 3b), which is fed to the ADC 8 clock input and the parallel register 9 input. The output from the ADC 8 is output amplifier 5 (Fig. 3B). This signal in the ADC 8 is converted into a digital code, then recorded in a parallel register 9, converted into a DAC 10 into a voltage that in the summing element 11 is summed with the initial threshold voltage U _on applied to the second input of the element 11. After that, the summing voltage is applied to threshold control input of the threshold element 6.

 After the end of the pulses at the additional output of the modulator 4 (Fig. 3b), the conversion of the signal at the output of the amplifier 5 into a digital code and its recording in the parallel register 9 is stopped. As a result, at the first input of the summing element 11 there will be a voltage that occurred at the output of the amplifier 5 at the time the last pulse appeared on the additional output of the modulator 4.

 In the absence of smoke in the receiving chamber 3, the signal at the output of amplifier 5 (Fig. 3c) is always less than the threshold threshold element 6, determined by the sum of the voltages at the output of the DAC 10 and at the second input of the summing element 11. The signal from the output of the amplifier 5 does not reach the output relay 7 , and the alarm will not appear.

 When smoke appears in the receiving chamber 3, the pulsed radiation from the emitter 1, reflected from the smoke particles and from the reflecting element 17, enters the photodetector 2 already amplified, and after amplification in the amplifier 5 is fed to the input of the threshold element 6. At a certain smoke concentration, the output signal amplifier 5 will exceed the threshold of the threshold element 6, as a result of which the output relay 7 is activated and the alarm signal appears on its output.

 The smoke detector (Fig. 2) works as follows.

When you turn on the modulator 4 for the first time, the managed key 12 is closed. The pulses from the additional output of the modulator 4 (Fig. 3b) are fed to the clock input of the ADC 8, the clock input of the first parallel register 9 and through a closed controlled key 12 to the clock input of the second parallel register 13. After the pulses have finished, the voltage that had the additional output of the modulator 4 the place at the output of the amplifier 5 (Fig. 3c) during the last pulse at the additional output of the modulator 4, is recorded in digital code in registers 9 and 13 and is present at the outputs of the DAC 10 and 14. In this case, the signal at the output of Ithel restriction 15 is equal to one, the voltage at the output of multiplier 16 equal to the initial threshold voltage U _on, and operation of the detector to the next power of the modulator 4 is similar to the detector in the first embodiment (FIG. 1).

 With any subsequent switching on of the modulator 4, the key 12 is open, as a result of which the voltage at the output of the additional DAC 14 is maintained, and the voltage at the output of the DAC 10 changes to the voltage that was at the output of the amplifier 5 during the last pulse at the additional output of the modulator 4.

 If the voltage at the output of the DAC 10 is greater than the voltage at the output of the additional DAC 14, then the signal at the output of the divider with a limit of 15 is 1, and the detector's operation until the next turn on of the modulator 4 is similar to the detector in the first embodiment (Fig. 1).

 If the voltage at the output of the DAC 10 is less than the voltage at the output of the DAC 14, then the signal at the output of the divider with a restriction of 15 is equal to the ratio of the voltage at the output of the DAC 10 to the voltage at the output of the DAC 14, and the voltage at the output of the multiplier 16, and therefore the control output the threshold of the threshold element 11 decreases, and the operation of the output relay 7 will occur at a lower voltage at the output of the amplifier 5 than in the detector according to the first embodiment (Fig. 1).

 Thus, the proposed technical solution in both cases (option I and option II) allows for high reliability of the smoke detector, eliminating false alarms when increasing reflections from the inner surface of the receiving chamber in the absence of smoke, and eliminating the cases of the detector not triggering if there is a receiver the chamber of the maximum concentration of smoke, with the deterioration of the properties of the optical system.

Claims (2)

 1. A smoke detector comprising a receiving chamber with an emitter and a photodetector located therein, a modulator, an amplifier, a threshold element and an output relay, the input of the emitter connected to the output of the modulator, and the output of the photodetector connected to the input of the amplifier, the emitter and photodetector installed in the receiving chamber so that direct radiation from the emitter does not fall on the photodetector, characterized in that the receiving chamber is equipped with a reflective element designed to cause the appearance of the reflected signal from it on in the absence of smoke, the modulator has an additional output, the signal from which is fed to the synchronizing input of the analog-to-digital converter and the clock input of the parallel register at the time the smoke detector starts working, the data input of the analog-to-digital converter is connected to the amplifier output connected to one of the threshold inputs element, the output of the analog-to-digital converter is connected to the input of the parallel register connected in series with the digital-to-analog converter and the summing element the volume whose output is connected to another input of the threshold element, the second input of the summing element is an input for supplying the initial threshold voltage, the output of the threshold element is connected to the output relay, the output of which is the output of the device.  2. A smoke detector containing a receiving chamber with an emitter and a photodetector located in it, a modulator, an amplifier, a threshold element and an output relay, the input of the emitter connected to the output of the modulator, and the output of the photodetector connected to the input of the amplifier, the emitter and photodetector installed in the receiving chamber so that direct radiation from the emitter does not fall on the photodetector, characterized in that the receiving chamber is equipped with a reflective element designed to cause the appearance of the reflected signal from it on the photodetector in the absence of smoke, and the modulator has an additional output, the signal from which is fed to the synchronizing input of the analog-to-digital converter, the clock input of the first parallel register and to the input of the controlled key at the time the smoke detector starts working, while the analog-to-digital converter is connected in series with the first parallel register, the first digital-to-analog converter, divider, multiplier and summing element, the output of which is connected to one of the inputs of the threshold element, each the first input of which is combined with another input of the analog-to-digital converter and connected to the amplifier output, the output of the controlled key through a chain of the second parallel register and the second digital-to-analog converter is connected to the second input of the divider, the second input of the second parallel register is connected to the output of the analog-to-digital converter, another the input of the summing element is connected to the output of the first digital-to-analog converter, the output of the threshold element is connected to the output relay, the output of which is the output m of the device, the second input of the multiplier is the input of the initial threshold voltage.

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