JPS5821036Y2 - Radiant fire detector - Google Patents

Description

[Detailed description of the invention] This invention is a two-wavelength radiation fire detection system that detects two different spectral components of radiant light generated by a fire, and issues a fire signal when the ratio of the magnitudes of these components exceeds a predetermined value. Concerning the improvement of utensils.

Used for detecting fires in conventional road tunnels, etc.2
The wavelength-based radiation fire detector is as shown in Figure 1.
A pair of light receiving sections B and R having different spectral sensitivities capture the radiant light generated by the flames of a fire, and low frequency amplifiers Ab and A capture the low frequency region of flickering caused by the flames.
When the output ratio of these amplifiers reaches a predetermined value, the comparator K operates and the switching circuit S is operated.

However, in order to detect weak radiant light generated by distant or small-scale fires in such a sensor, the amplification of the amplifier is increased to make it highly sensitive. quickly reaches saturation,
It had the drawback of not being able to function despite a fire.

Therefore, in order to eliminate such drawbacks, as shown in FIG. 2, multiple stages of amplifiers Ab1. Ab2.
Ab3 and Ar1. Ar2. Ar3 is provided, and each stage of amplifiers Abl "Ar1.Ab2" Ar2 and Ab3.
A predetermined ratio of the output of the amplifier in the amplification stage where the intensity of the internal radiation light of Ar3 is appropriate and does not reach the saturation state is set to 1. A radiation type fire detector (see Japanese Utility Model Application No. 51-85853) was proposed in which the fire is detected by K2 or K3, the operation thereof is detected by an OR circuit G, and a switching circuit S is operated.

However, increasing the number of amplifier stages without limit and adapting the range from weak radiation light to powerful radiation light would make the detector expensive and uneconomical, so it is still not suitable for large-scale or very close fires. We had no choice but to create a design that left inactive parts.

In view of the above points, this invention was designed to eliminate the above drawbacks by adding a simple circuit, and will be explained below with reference to an embodiment circuit shown in FIG.

In the figure, Vc and Vo are the positive and zero potential terminals of the power supply, and a Zener diode ZD is connected to both ends via a resistor R1, so that the midpoint thereof becomes the intermediate potential terminal V/.

b is an optical filter with a spectral sensitivity of 0.6 to 0.
．． A solar cell for a so-called blue light receiving section that is installed to receive radiant light with a short wavelength of 75 microns, r is an optical filter similar to b, and the spectral sensitivity is 0.8 ~
This is a solar cell for a so-called red light receiving section that is installed to receive radiant light with a long wavelength between 1.1 microns, and resistors R2 and R3 are connected in parallel to both solar cells S and R, respectively. Resistor R4 and capacitor C1 or resistor R6
and an inverting input terminal of a 3-20 Hz low frequency AC amplifier Ab1 or Ar1, which is formed of, for example, an OP amplifier, and is connected between terminals Vc and Vo via a capacitor C2.

Further, the non-inverting input terminal is connected to the cathode of the solar cell S, r and to the connection point V/ between the resistor R1 and the Zener diode ZD.

Furthermore, amplifier Ab1. The output terminal of Ar1 is connected to resistor R6 and capacitor C3 or resistor R? and capacitor C4 to the first stage amplifier Ab1. Similarly to Ar 1, the terminal Vc
, Vo and V' are connected to the second stage 3-OHz low frequency AC amplifier Ab2 or Ar2 consisting of an OP amplifier.
is connected to the inverting input terminal of

Moreover, these AC amplifiers Ab, , Ar 1. Ab
2 and Ar2 are resistors R8 and Ro connected in series between the terminals Vc and Vo, and a parallel circuit consisting of a diode D1 resistor R1o and a resistor R11 connected in series between the midpoint thereof and the terminal Vo, and a capacitor C5. The amplifier Ab1. In the smoothing circuit provided in Ar1, the comparator provided between the terminals Vc and Vo is connected to the inverting and non-inverting input terminals of 1, and the smoothing circuit provided in the amplifier Ab2yAx2 is connected to the comparator provided between the terminals Vc and Vo. Similarly, it is connected to two inverting and non-inverting inputs of a comparator provided between terminals Vc and Vo.

Furthermore, / is a comparator connected between terminals Vc and Vo,
Its inverting input terminal is connected to the connection point of resistors R1□ and R13 connected between the terminals Vc and V', and its non-inverting input terminal is connected to the anode of the solar cell r for the red light receiving section, and a low-sensitivity amplifier is connected. The circuit is configured to operate at the output voltage of the solar cell r immediately before Ab 1 t Ar 1 is saturated, and detects the DC component of the radiant light.

And these comparators have 1. The outputs of 2 and 2' are connected to the terminal vO through a diode d' and a resistor R', respectively, and an output terminal OUT is provided at the connection point between the resistor R' and the diode d'.

Next, to explain the operation of the above-mentioned radiation fire detector, in normal environmental light, blue light is stronger than red light, so even if those lights are
Amplifier Ab1゜Ab 2 , Ar
The AC output is amplified through 1. to 2
Even if input to the input terminal of , the relationship of blue light > red light is maintained, so the comparator inputs 1. 2 does not operate, and comparator 1 does not operate because the red light is weak and does not exceed a predetermined value, and no output is produced at the output terminal OUT, and the switching circuit (not shown) is not operated.

However, a fire broke out and the flickering frequency increased from 3 to 2.
When radiant light in the relationship between red light and blue light having a frequency of 0 Hz enters the solar cells S and R, amplifiers Ab1 and Ab2 or amplifier Ar1 are activated in the case of a fire occurring far away.
The signal is amplified in two stages by Ar2 and Ar2, and then input to the comparator 2 via a smoothing circuit.

In this case, the spectral distribution of the light caused by the fire is red light > blue light, so the comparator 2 reverses its input state and operates to generate an output at the output terminal OUT and issue an alarm via a switching circuit (not shown). Also, if the fire is relatively close to the detector, the radiated light will be relatively thick, so the amplifier Ab2. A2 becomes saturated and becomes inoperable, but the first-stage amplifiers Ab and yAr are amplified normally without becoming saturated, and the input of 1 is inverted to the comparator via the smoothing circuit. , 1 operates in the comparator and produces an output at the output terminal OUT to notify that there is a fire.

In addition, if a large-scale fire occurs near the detector or if a large-scale fire occurs, all amplified giAb1+Ab2. Ar
1. Ar2 becomes saturated when its input signal becomes excessive and becomes inoperable, but in the case of a comparator that simply compares signals using DC, its input exceeds a predetermined value and is inverted and operates, so the output terminal OUT An output is generated to notify the fire.

In this case, it is a hot theory that by installing ′ in the comparator, it is now possible to reliably detect even large-scale fires, as well as fires that occur near the detector.
Since the comparator receives the input '' from the solar cell r that receives red light, that is, long wavelength light that is less likely to be included in ambient light and noise light, it operates stably with fewer malfunctions.

Since the radiation type fire detector of this invention is configured and set as described above, it is a radiation type fire detector that detects and operates from weak radiant light to strong radiant light generated by fire, and is less likely to malfunction or miss alarms. There is an effect that can be obtained.

[Brief explanation of the drawing]

1 and 2 are block diagrams of conventional radiation type fire detectors, and FIG. 3 is a circuit diagram of an embodiment of the radiation type fire detector of the present invention. b, r...Solar cell, Abl, Ab2
, Ar1jAr2”...Low frequency AC amplifier, Kl
t K2 + K'...Comparator.

Claims (1)

[Scope of utility model registration request] A sensor for detecting the characteristic flicker of flame caused by a fire, comprising a pair of light receiving sections each having a different sensitive spectral range, and a separate one or multiple stages of low frequency AC amplifiers for amplifying the respective outputs. and one or more comparators for comparing the outputs of the amplifiers for each amplification stage. A radiation type fire detector equipped with a comparator that detects DC output, and an alarm is issued by the operation of this comparator or the above-mentioned comparator.