JPS6123785Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a photoelectric smoke detection and notification device that can avoid false alarms by focusing on a flow pattern different from the original ignition and smoke emission, such as smoking exhaust or fluid containing fine dust. Generally, in the case of photoelectric fire detection devices, which use a photoreceptor to detect when smoke gas is introduced into the chamber at the initial stage of a fire and interrupts the irradiation beam of a light emitter, it is possible to detect gas containing smoke particles. A chamber is used that can be introduced into the dark box through an opening, and is configured to amplify the sensitive output of the photoreceptor and guide it to the alarm circuit. By the way, the sensitivity of the detection circuit can usually be adjusted by adjusting the gain of the amplifier, but if the flow pattern of the fluid flowing into the chamber is due to smoking indoors, or if the fluid contains fine dust, it may be affected by the outbreak of a fire. Even though the situation is different from that of continuous diffusion and spread, and the smoke concentration in the gas gradually increases, if the detection circuit is uniformly set to high sensitivity, it will be possible to detect a fluid flow that is not caused by a fire. This may cause false alarms to be sent out. In addition, one of the causes of the above-mentioned false alarm may be reflected scattered light within the chamber or external scattered light, but this is related to the ease of introducing smoke gas into the chamber and the structure to prevent scattering, as well as the detection circuit. It also concerns the factors of sensitivity and signal-to-noise ratio. Based on the flow pattern of the fire-smoking fluid to be detected, the present invention detects two or more consecutive times in synchronization with pulsed light emission when a detection level exceeding a certain standard is reached, regardless of the structure of the collection chamber. To provide a smoke detection and alarm device capable of issuing an alarm only when a signal is sent out. An embodiment of the present invention will be described in detail below based on the drawings. First of all, Figure 1 is a comprehensive block wiring diagram of this invention.
The light emitter L is connected to a pulse generation source PG to emit a light beam in a pulsed manner at a constant period, and the light receiver R is connected to a pulse generation source PG to emit a light beam in a pulsed manner at a constant period.
Add the sensitive output to the amplifier AMP with gain adjustment function. DEL is the emission period of the above light beam, i.e.

[Table] F is a coincidence counter that has a built-in flip-flop that counts the detection pulses from the gate circuit and a gate that determines the count, and sends out a coincidence output for the first time when the planned number of detection pulses n has been counted. It is something to do. This coincidence counter has a set terminal 1 and a reset terminal 2 as input terminals, and a detection signal is applied from its output terminal E to the notification means AL. receive signals from each. To explain Figure 2 here,
Figure a shows the fluid concentration distribution before it is introduced into the smoke detection chamber, and AF1 to AF3 fluctuate irregularly due to pulsations such as smoking exhaust, and as a detection circuit, there are peak values that exceed a certain reference level E _B. In contrast, the smoke gas that rises as a result of a fire
As time passes, its concentration increases continuously, naturally exhibiting a flow pattern that exceeds the detection level. Figure b is a continuous pulse graph of pulsed light emission that is repeatedly driven at a constant period by the pulse generation source PG, and the photoreceptor gradually sends out a light reception output with a slight delay to this light emission pulse. Figure c is a graph of a detected pulse that is slightly delayed from the pulse sending period of figure b at the time when the fluid flow pattern exceeds the detection level, and K ₁ and K ₃ are graphs where one intermittent detection output is noticeable. In addition, _K7 to _K9 indicate that the detection pulses are sent out three times in succession in this embodiment. Therefore, sending out only one detection pulse does not send a notification signal to the alarm means, and it is not until the detection pulse is sent out at least two times in succession that the signal SG notifying that smoke fluid has been detected is generated. The signal is sent from the output terminal of the coincidence counter as shown in d of the same figure. This alarm sending period, ie, the period during which the logic signal "1" appears at the output terminal E of the coincidence counter, is the number of times the smoke detection pulse is sent out during the clock pulse sending period of the pulse generation source (where m>n, and in this embodiment Then, it continues for m times the period multiplied by n=2). As explained above, the present invention has a configuration in which a certain detection standard level is set when detecting smoking fluid due to a fire, and an alarm command is not issued unless a detection pulse is continuously sent out. Since it can be easily separated from ordinary air and fluids, the chances of being misled by false alarms can be minimized.
In addition, since the chance that true information and false information due to actual smoke overlap during the emission period occurs with an extremely low probability and is rare, it is advantageous to adopt a chamber structure that facilitates gas inflow. . In other words, disturbances that cause false information due to external light or induced surges can be prevented by adding protection to the detection circuit, placing a photoreceptor in the chamber, or using a structure to reduce scattered light. Because you can. Furthermore, there is no need to readjust the sensitivity of the variable gain amplifier one by one, and the influence of scattered light within the chamber is suppressed to a negligible level.
This has the practical benefit of making it possible to centrally set the characteristics of the detection circuit only by classifying smoke fluid and general gas based on their flow patterns.

[Brief explanation of the drawing]

FIG. 1 is a circuit connection diagram in an embodiment of the present invention, and FIG. 2 is a graph showing the state of each part related to the circuit shown in FIG. PG...Pulse source, L...Light emitter, R...
Photoreceptor, DEL...Delay circuit, AMP...Variable gain amplifier, G...Gate circuit with level comparator, F...
...match counter.

Claims (1)

[Scope of utility model registration request] In a smoke detection circuit in which a photoreceptor detects that the irradiation light beam intermittently emitted by a pulse generation source has been scattered by the introduction of fire-smoking fluid into the chamber, the photoreceptor is sensitive to the intermittent emitted light beam with a slight delay. A variable gain amplifier that receives the received light output, and a delayed output in which the pulse output of the amplifier that exceeds a certain level and the clock pulse from the pulse generation source are delayed by a delay circuit by a time corresponding to the delay time until the photoreceptor is sensitive. comprises a gate circuit with a level comparator that outputs one logic output when both are input, and a coincidence counter including a flip-flop that counts the output of the gate circuit, and the output of the gate circuit is at least n consecutive times. 1. A photoelectric smoke detection and notification device, characterized in that an alarm is issued for a period m times the clock pulse period of the pulse generation source only when m times.