JPS5831278Y2 - Dual wavelength radiation sensor - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a two-wavelength radiation sensor that detects a fire by detecting the flickering of two different spectral components of radiant light.

The light radiated from the sun, illumination lights, etc. and the light radiated from flames during a fire have short wavelength spectral components of 06 to 09 microns and long wavelength spectral components of 08 to 1.1 microns.
Regarding the magnitude of flicker at ~20 Hz, radiant light from the sun or lighting lamps has a large flicker in short wavelength spectral components, and radiant light from fire flames has a large flicker in long wavelength spectral components.

Dual-wavelength radiation detectors detect fires by using the difference in the flickering size between environmental light such as sunlight or illumination light and flame radiant light, which detects light in the short and long wavelength spectra. A pair of light receiving sections each detecting separately, one or more stages of low frequency amplifiers amplifying the alternating current output of each of the pair of light receiving sections, and an output ratio of the outputs of each stage of the low frequency amplifiers. It is comprised of one or more comparators that are activated when the value reaches a predetermined value, and a signal sending circuit that is controlled by the output of the comparators and sends out a fire signal.

This invention provides a two-wavelength radiation sensor in which the comparator can stably detect the output of the low-frequency amplifier.

An embodiment of this invention will be described below with reference to the drawings.

In Fig. 1, SB1 is a solar cell equipped with an optical filter F1 in front of the light-receiving surface that transmits light of a short wavelength spectrum, e.g., 06 to 09 microns (hereinafter referred to as blue light), and a resistor R1 in parallel.SB2 is a solar cell in front of the light-receiving surface. The solar cell is equipped with an optical filter F2 that transmits light with a long wavelength spectrum, for example, 08 to 1.1 microns (hereinafter referred to as red light) on one side, and a resistor R2 is connected in parallel.

One ends of the solar cells SB1 and SB2 are connected to the input terminals of low frequency amplifiers Am and Am, respectively, which amplify an AC signal of 3~20H2 through a resistor R3 and a capacitor C1 or a resistor R4 and a capacitor C2 connected in series. ,
The other ends are both connected to (→terminal 2).

Through the output capacitor C8 of the amplifier ArrL1 (1)
A smoothing circuit S1 connected in series between terminals 1 and 2 is connected to a junction point between resistors R3 and R6, and this junction point is connected to terminal 2 through a diode D1, a resistor R7, and a capacitor c4 having a parallel resistor R6. The connection point between the resistor R7 and the capacitor C4 of this smoothing circuit S is connected to the non-inverting input terminal of a comparator CM, which is made up of, for example, an arithmetic divider.

The output of the amplifier A''m2 is connected through the capacitor C1 to the connection point r between the resistors R9 and R10 of the smoothing circuit S connected in series between terminals 1 and 2, and this connection point r is connected to the diode D2 and the resistor R11 in parallel. This smoothing circuit S is connected to terminal 2 through a capacitor C6 having a resistor R12.
The connection point between the resistor R, i of 2 and the capacitor C6 is the comparator CM.
is connected to the inverting input terminal of

The output of this comparator CM is connected to terminal 2 through resistor R13 and capacitor C7.
The connection point 7 is connected to the anode of a programmable unijunction transistor (hereinafter referred to as P[J, T), PUT, whose gate is connected to the connection point between resistors RH and R15, which are connected in series between terminals 1 and 2. The cathode of this PUT is connected to terminal 2 through resistors R16 and R17.

The connection point between these resistors R16 and R1□ has a collector with a resistance ft.
The terminal 1 is connected to the base of a transistor Tr whose emitter is connected to the terminal 2 through 1a.

In order to prohibit the comparator CM from operating when the solar cells SB1 and SB2 are not receiving flame radiant light, resistors R5 and R6 are set so that the potential of the connection point S is higher than the potential of the connection point R.

Values for RQ and Rlo are chosen.

Next, the operation will be explained.

When the solar cells SB1 and SB2 detect light and produce an output, the alternating current component of this output due to flickering light is amplified by low frequency amplifiers Afil and Am2, respectively.

The AC output of the amplifier Am enters the smoothing circuit S1, where it is rectified and smoothed by the diode D1 and the capacitor C4, and the smoothed output of the smoothing circuit S is input to the non-inverting input terminal of the comparator CM. b) Lu.

Also, amplifier A? The AC output of 712 is input to a smoothing circuit S2, where it is rectified and smoothed by a diode D2 and a capacitor C6, and the smoothed output of this smoothing circuit S2 is sent to a comparator CM.
is input to the inverting input terminal of

This comparator CM does not operate if the output of the smoothing circuit S1 is greater than the output of 82, but if the output of the smoothing circuit S2 is greater than the output of 81
When the output becomes larger than the output of , it operates and produces an output, and this output causes the capacitor C7 to undergo a light shock, and the potential at the anode 7 of the PLTT rises.

When this anode potential becomes higher than the gonide potential, P'U
When T becomes conductive, the transistor Tr becomes conductive, and due to the conduction of the transistor Tr, the receiver (,
(not shown).

By the way, the environmental light is shown in part A of Fig. 2a, t', ,b,
The flicker of the blue light BA is larger than the flicker of the red □ light R'l.

Solar cells SB absorb this kind of environmental light. When SB2 detects this, the amplifier Ail produces an AC output at point b, shown as vb in FIG. 2, and the amplifier Am2 produces an AC output at point r, shown as Vr.

With the AC outputs vb and yr of these amplifiers Am and Am2,
Smoothing circuit S1 produces an output shown as vS in FIG. 2C, and smoothing circuit S2 produces an output lower than vS1, shown as vS2.

Therefore, comparator CM does not operate, and PUT and transistor Tr are not conducted.

However, when the solar cells S, B, . . . and SB2 detect the radiant light of the flame, the flicker of the red light 1 is larger than the flicker of the blue light Bl in the radiant light of the flame, as shown in the sub-portion of FIG. 2a. Amplifier A, AC output vb at point b of ml and amplifier Am
The AC output Vr at point r in 2 is output' as shown in Figure 2.
The amplitude of Vr becomes larger than the amplitude of output vb.

For this reason, smoothing output of smoothing circuit S1 ■ S1 and smoothing circuit S
The smoothed output ■S of 2 is the output ■S, as shown in Figure 2C.
■1. S, grows by 1,000.

When this output S2 becomes larger than vS1, the comparator CM operates and produces the output shown in FIG.

When the anode potential of PUT becomes higher than the gate potential due to charging of capacitor C7, P[JT becomes conductive and this PUT
Due to the conduction of the transistor Tr, the transistor Tr is made conductive as shown in FIG. 2e, and a fire signal is sent to the receiver (not shown).

In addition, as shown in FIG.
Multi-stage amplification is performed using m2g, and the ratio of the amplified output of each stage is calculated using comparator C.
When making a judgment using M1 to CM3, use the amplification and width devices Am11 to
Am, 3 t A'', and multiple outputs of 21 to Q23 may be input to comparators CM1 to CM through smoothing circuits 81□ to S1. and S2□ to S23, respectively.

According to this invention, the flickering components of blue light and red light are rectified and smoothed by each output of the AC amplifier, each output of the device, and each smoothing circuit, and then input to the comparator. A two-wavelength radiation sensor capable of stably detecting the flicker ratio of light and red light using a comparator is obtained.

1 Also, the output of each AC amplifier is that -e4-L circuit special,
However, the comparator can reliably detect its output ratio due to the effect of the smoothing circuit.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of one embodiment of a two-wavelength radiation sensor according to this invention, Fig. 2 is a diagram explaining the operation of the embodiment of Fig. 1, and Fig. 3 is a diagram of another embodiment of this invention. It is a block diagram. SB1, 5B2=-・Light receiving element, Am, , Am2
++・AC amplifier, Sl, B2...Smoothing circuit, CM・
...Comparator.

Claims (1)

[Claims for Utility Model Registration] ■ A pair of light receiving sections that separately detect two different spectral components of radiated light, and one or more stages that separately amplify the non-AC output of the pair of light receiving sections. In a two-wavelength radiation sensor comprising an AC amplifier and one or more comparators that detect the output of each stage of the AC amplifier and determine the output ratio, there is a A two-wavelength radiation sensor characterized in that each wavelength is provided with a smoothing circuit. 2. The two-wavelength radiation sensor according to claim 1, wherein the smoothing circuit includes a circuit for half-wave rectifying the output of the AC amplifier and a circuit for smoothing the output of this circuit.