JPS593698A - Photoelectric smoke sensor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric smoke detector which makes it possible to obtain output pressures that are analogously matched to the latitude of the smoke.

FIG. 1 shows an example of a conventional photoelectric smoke detector of this kind. The fc LED, which is provided as a light emitting element, is lit with direct current by the output of the power supply Vcc, and the light from this LED is sent to the light receiving element, followed by the SPD, and smoke is generated.
At the time of c, the scattered light from the LED is received by the SPD. Therefore, this SPD is configured to output a full current signal at a direct current level depending on the amount of the scattered light.

OPl is a first arithmetic amplification circuit, and the first arithmetic amplification circuit OP and the second arithmetic amplification circuit OP2 provide
Output of the above SPD? The width of the 1θ flow is amplified, and fcli! , so that the output voltage can be obtained.

However, in such a conventional example, the LED is set to be lit for one page.
In addition to solving the problem of requiring a full power supply in the Otani region, there is also the problem of heat generation in the LED itself, which cannot be ignored, and the first and second operational amplifier circuits OP, OP2 are configured as DC multipliers. Therefore, although it is not possible to achieve a high increase in width, the output current of the SPD is very small, and it is difficult to obtain a high smoke detection function. Atsuka has a hard time accepting the situation as it is.

The present invention has been provided in view of the above points, and has an output Kameda that corresponds to the smoke shrimp in an analog manner. To obtain a smoke detection function that is stable and highly sensitive without being affected by DC drift, even though it is possible to perform more detailed monitoring and control. The purpose of this invention is to provide a photoelectric smoke detector that can perform

An embodiment of the present invention will be described in detail below with reference to the drawings. +6)d
The constant voltage circuit is composed of transistors Tr, zener diodes ZD, resistors R, etc., and includes all circuits described later - predetermined electronic circuits. give. Reference numeral i+1 is a pulse drive circuit, which is configured to cause the LEDi to intermittently remain open for a predetermined period of time to emit light. (2) is an AC amplifier, and the above LE
Scattered light from light smoke from D? It is configured to alternating current and amplifying the output of the SPD that receives light, and the output of this AC amplifier (2) is input to the switching circuit (3) K, and the output of the pulse drive circuit fi+ outputs the signal during the period when the LED emits light. Only the output of the AC amplifier (2) passes through this switching circuit (3) and is stored in the sensor C11. [Gakuteko] The pressure at the terminal tube of the sensor C9 is impedance-converted and DC-amplified in the DC amplification circuit (4), and a core outflow force corresponding to the detected smoke in an analog manner is output to the output end (5). You will get it. Pulse drive circuit ++) U, transistors Trt to Tr4, resistors 'i
A, R2, R4~R7, R9~R1+, C, /Denser C, , C2 When the n1 transistor Tr is intermittently turned on, the LEDI-j is turned on as shown in FIG. 3(a).
As shown in the figure, the light is emitted intermittently. A.C.
Amplifier (2) includes transistors Tr5 to Tr8 and resistor R1.
2 to R19, capacitors c8, c5 to C7, etc., and the scattered light due to the smoke of the light emitting output of the LED?
This is to amplify the output of the SPD that receives the light, and as mentioned above, since the LED is designed to emit light intermittently, the output of the sPD also occurs intermittently, and this is done in the AC amplifier (2). The AC amplitude is increased as the output voltage increases, and an output waveform as shown in FIG. 3(b) is generated at both ends of the resistor RI9. (3) is a switching circuit, which is composed of a junction F'ETTre and a capacitor C8, and the gate input of this junction FETTrg is inputted from a bias circuit (7). Here, the bias circuit (7) includes resistors Rn, R2
0% Zener diode ZD, diode D1, etc., each circuit downstream of the constant voltage circuit (6) has a negative voltage with respect to the talandry:/? The pulse output of the J) Luz front circuit ill is superimposed on the output voltage ratio of the bias circuit (7) and input to the gate of the junction FET Tre through the entire pulse output sound conditioner C6. It is. Therefore, this Junkshi 3F
Switching episode I consisting of E T Tre! /! Jt
As shown in FIG. 3(c), 31 is turned on synchronously during the bright light interval of the LED, so that the voltage across the resistor R390 is accumulated and memorized across the capacitor C8.
A voltage as shown in FIG. 3(d) is obtained across s.

Therefore, this], 17 Jinsa C, l's both pancreatic army nia: all,
1 Self-current, amplifying circuit (4) junction 3-in FET
Replace impedance f with Trio, and add operational amplifier O
The current is amplified by 1 at P, and the output voltage ratio as shown in Fig. 3(e) is obtained at the output terminal (5). In addition, it is composed of resistors R, 21 to R26.

Figure 4 shows an example in which the entire switching circuit (3) is configured using a general IC-based analog switch ASWi for castor power supply. Since the analog switch ASW does not have sufficient open impedance as a switch, it is necessary to be careful that the charge of the capacitor CI+ is discharged toward the resistor RI9. Another example of the configuration of the impedance conversion circuit section is shown, in which the impedance conversion is performed by a buffer circuit using an operational amplifier OP, and in this case, almost the same operation as in the embodiment described above can be obtained. The problem is whether it is the input current of the amplifier OP or not, and it will completely affect the charging and discharging of the capacitor C8.

Since the "non-explosion" is configured as described above, it is possible to create a high-intensity output system that responds to the amount of smoke in an analog manner, without requiring a high-intensity system. It has a highly sensitive smoke detection function that makes it easy to perform a variety of notification and control operation sounds. It has an effect that can be stably obtained.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional example, Fig. 2 is a circuit diagram of an embodiment of the present invention, Fig. 3 (a) to (e) is a time chart of improvement, and Fig. 4 is an uninvented - 6th embodiment example. switch, ・:, I
(1) is a main part circuit diagram of another example of the configuration of the impedance switching circuit of the present invention; Warm J circuit, (21fdA
C amplifier, (3) is a switching circuit, (4) is a 10 current amplification circuit, (5) is an output end, and a C811-L capacitor. Agent Patent Attorney Ishi Origin: Figure 7, Figure 3, Figure 4

Claims (1)

[Claims] (1) Light emitting element? A pulse opening circuit that stabs intermittently,
An AC amplifier that amplifies the output of the light receiving element, a switching circuit that turns on and off in synchronization with the output of the pulse cutoff circuit, and a switch circuit that switches the output of the AC amplifier. 1) A capacitor that maintains the white voltage and a DC amplification circuit that amplifies the terminal cylinder heavy pressure of this sensor, and the output voltage corresponding to the smoke sensitivity in an analog manner increases the pressure above. A photoelectric smoke detector which is entirely characterized by being obtained at the output end of a DC amplification circuit.