JP2539948B2 - Dimming type smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention has a light emitting unit and a light receiving unit separately arranged, and a change of a monitoring beam emitted from the light emitting unit due to invasion of smoke on the light receiving unit side. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimming type separated smoke sensor that detects and warns.

[Prior Art] Conventionally, in this type of dimming separation type smoke sensor, a light emitting unit and a light receiving unit are arranged to face each other across a smoke detection space, and a monitoring beam by smoke flowing into the smoke detection space is provided. The fire is judged from the change in the received light output due to the dimming of the light.

[Problems to be Solved by the Invention] However, in such a conventional dimming-type separated smoke detector, a fire occurs due to a change in received light output when one monitoring beam is dimmed by smoke. Was detected,
For example, dew condensation occurs on the light projection part and the monitoring beam dims,
Even if fog or the like is generated in the outdoor installation and the monitoring beam is dimmed, there is a problem in that it is judged as a fire due to the decrease in the light reception output, and a false alarm is generated.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a dimming-type separated smoke sensor that can detect a fire quickly and surely without causing a false alarm.

[Means for Solving the Problem] The present invention for achieving this object is configured as follows.

First, according to the present invention, a light emitting portion and a light receiving portion are separately arranged, and a dimming separation type in which the light receiving portion detects a change due to invasion of smoke in a monitoring beam emitted from the light emitting portion and issues an alarm. For smoke detectors.

According to the present invention with respect to such a dimming type separated smoke sensor, at least two sets of a light emitting part and a light receiving part are vertically arranged at a predetermined interval and a monitoring beam which can be identified for each set is provided. A calculation unit that calculates the ascending speed of an object that rises from the time difference between when the lower monitoring beam is blocked by the light-receiving unit side until the upper monitoring beam is blocked, and the rising speed calculated by this calculating unit And a judging section for judging whether or not there is a fire.

[Operation] The following operation can be obtained in the dimming separation type smoke sensor of the present invention having such a configuration.

First, the smoke generated during a fire rises with a change in shade, and it can be considered that one smoke ball rises in a portion with a high smoke concentration.

Therefore, in the present invention, at least two monitoring beams are arranged above and below, the time difference is detected from the change in the received light output when the smoke ball crosses the monitoring beam from the bottom to the top, and the smoke ball rises from this time difference. Find the speed. It has been experimentally confirmed that the rising speed of smoke at the time of fire is 0.5 m / s or more, so the detected rising speed is 0.
If it is 5m / s or more, it is judged as a fire.

On the other hand, in the case of dew condensation, fog, etc., the two monitoring beams diminish similarly, and in this case, the rising speed cannot be detected, and thus it is possible to reliably prevent erroneous determination as a fire. .

[Embodiment] FIG. 1 is a configuration diagram of an embodiment showing one embodiment of the present invention.

In FIG. 1, 10 is a light projecting unit, 12 is a light receiving unit, and 14 is a receiver. The light projecting unit 10 and the light receiving unit 12 are separately arranged with a smoke detection space interposed therebetween. In the present invention, the light projecting unit 10 to the light receiving unit are arranged.
Two monitoring beams 16 and 18 arranged above and below 12 are projected.

A light emission drive unit 20 is provided in the light projecting unit 10, and the light emission drive unit 20 is provided.
Light emitting element consisting of laser diode or LED
-1, 22-2 is driven. Light from the light emitting elements 22-1 and 22-2 is returned to the parallel monitoring beams 16 and 18 by the lenses 24-1 and 24-2 and projected onto the light receiving unit 12. Here, the light emission drive unit 20 intermittently performs light emission drive in order to prolong the life of the light emitting elements 22-1 and 22-2 and reduce power consumption.

The light receiving unit 12 includes a light receiving element 26 such as a photodiode.
-1,26-2 are provided. The light receiving outputs of the light receiving elements 26-1 and 26-2 are amplified by the amplifying unit 28 and then given to the calculating unit 30 as the lower light receiving output A1 and the upper light receiving output A2. Arithmetic unit
30 detects the time difference ΔT from the change in the received light output A1 to the change in the received light output A2 due to the dimming when smoke crosses the monitor beams 16 and 18 from the lower side. Since the installation interval L is predetermined, the smoke rising speed V
Is calculated as V = L / ΔT. The rising speed V calculated by the calculation unit 30 is given to the determination unit 32, and the threshold speed set in the determination unit 32 is set.
When the voltage exceeds Vth, it is determined that a fire has occurred, and a fire detection signal is sent to the receiver 14.

FIG. 2 is a flow chart showing the fire detection processing on the side of the light receiving unit 12 in the embodiment of FIG.

When the light emitting unit 10 and the light receiving unit 12 in FIG. 1 are turned on,
The process shown in FIG. 2 is started. First, in step S1 (hereinafter “step” is omitted), the installation interval L above and below the monitoring beams 16 and 18
In addition, initial settings such as the speed threshold Vth for judging fire.

Next, in S2, it is checked whether the received light output A1 is less than or equal to the threshold level L1 set in a portion slightly lower than the steady monitoring level.

In the case of the lower light-receiving output A1 in FIG. 3, the light-receiving output at time T ₀
When A1 becomes equal to or lower than the threshold level L1, the process proceeds to S3, and it is checked whether or not the light receiving output is down by a predetermined level ΔA or more within a fixed time. For lower light output A1 of FIG. 3 (a), the time T ₀
Since the decrease in the received light output at 1 is due to the passage of the smoke ball, the received light output is reduced to a level equal to or higher than the specified level ΔA within a certain time. Therefore, the process proceeds to S4 and the peak value time T1 is stored.

Next, in S5, it is checked whether the light reception output A2 has become equal to or lower than the threshold level L1. If the light reception output A2 has not decreased to the threshold level L1, wait for a predetermined time in S6, and wait until the light reception output A2 decreases to the threshold level L1 or lower. Of course, if the received light output A2 does not drop below the threshold level L1 within the predetermined time, it is determined that the malfunction occurs due to the dimming of only the monitoring beam 16 on the lower side, for example, dimming due to falling leaves or the passage of a person, and from S6 to S2 again. Return to processing.

In the case of FIG. 3, since the light reception output A2 is below the threshold level L1 before the elapse of the predetermined time of S6, the process proceeds to S7, and it is checked whether or not the predetermined level ΔA is decreased within a predetermined time, and the smoke ball If it is due to the passage of No. 2, the received light output A2 of the predetermined level ΔA or more can be reduced within a fixed time, so the process proceeds to S8 and the peak value time T2 is stored.

Then, in S9, the peak value times T1, T stored in S4 and S8 are stored.
2, the time T when the fireball crosses the surveillance beam 16
Based on 1 and the time T2 when the surveillance beam 18 was crossed, the time difference Δ
Find T. Next, in S10, the installation interval L1 above and below the monitoring beams 16 and 18 is determined.
Calculate by T. Here, the installation interval L1 above and below the monitoring beams 16 and 18 is set to, for example, about L1 = 0.1 m.

If the rising speed V is calculated in S10, it is checked in S11 whether the rising speed V is equal to or higher than the threshold Vth for judging the fire. The threshold value Vth of the rising speed to be judged as a fire is, for example, Vth =
If it is 0.5 m / s and is equal to or higher than the threshold speed Vth, the process proceeds to S12 and a fire signal is sent. Of course, if it is less than the threshold speed Vth, the process returns to S2 and the same processing is repeated.

On the other hand, if the ascending speed is too fast, that is, the monitoring beam
If 16 and 18 are blocked at almost the same time, there is a high possibility of people passing through, so in this case it is better to return to S2 again.

In the flowchart of FIG. 2, it is determined whether or not there is a fire by one calculation of the ascending speed V in S10. However, the routine for calculating the ascending speed V is repeated a plurality of times to calculate the average value of the calculation results. May be used to improve the reliability of the fire judgment.

Further, the resolution on the time axis of the lower and upper received light outputs A1 and A2 shown in FIG. 3 depends on the light emission period by the light projecting unit 10 in FIG. It should be short.

FIG. 4 is a block diagram of an embodiment showing another embodiment of the present invention. In the embodiment of FIG. 1, the monitoring beams 16 and 18 are narrowed to parallel beams so that they can be distinguished on the side of the light receiving portion 12. However, this embodiment is characterized in that the monitoring beams 16 and 18 are modulated at different frequencies so that they can be distinguished on the light receiving unit 12 side.

In FIG. 4, modulation units 34-1 and 34-2 are provided for the light emission drive unit 20 of the light projecting unit 10, and the modulation unit 34-1 sends a modulation signal of frequency f1 to the light emitting element 22-1. Output and drive light emission. Further, the modulator 34-2 outputs a modulated signal of frequency f2 to the light emitting element 22-2 to drive light emission. Lens 24-1, 24-2
The monitoring beams 16 and 18 from are not narrowed down to parallel beams, and are incident on the light receiving elements 26-1 and 26-2 on the light receiving unit 12 side in an overlapping manner. Demodulators 36-1 and 36-2 are provided for the light-receiving elements 26-1 and 26-2 of the light-receiving unit 12, and demodulate the modulated light-receiving signal with different local oscillation frequencies f1 and f2. Amplifier 2
The configurations of 8, the arithmetic unit 30, and the determination unit 32 are the same as those in the embodiment of FIG.

FIG. 5 is a block diagram of an embodiment showing another embodiment of the present invention.
An optical bandpass filter is used to distinguish between the two sides.

In FIG. 5, the light emitting elements 22-1, 22 provided in the light projecting section 10 are shown.
-2 and the lenses 24-1 and 24-2 are provided with a bandpass filter 38-1 having a center wavelength λ1 and a bandpass filter 38-2 having a center wavelength λ2, and monitor beams 16 and 18 having different wavelengths are provided.
To project. A bandpass filter 40-1 having a center wavelength λ1 and a bandpass filter 40-2 having a center wavelength λ2 are arranged in front of the light receiving elements 26-1 and 26-2 of the light receiving unit 12. Thus, the bandpass filters 38-1 and 38-2 having different passing wavelength bands provided on the light projecting unit 10 side and the bandpass filters 40-1, 40-2 having different passing wavelength bands provided on the light receiving unit 12 side are also provided. Thus, the monitoring beams 16 and 18 arranged above and below can be distinguished on the light receiving unit 12 side.

In the above embodiment, the case where the two monitoring beams are arranged above and below is taken as an example, but the number of the monitoring beams is two.
It is also possible to arrange a plurality of above-mentioned books and to similarly judge the fire by the rising speed based on the time difference between the smoke ball crossing the lower surveillance beam and the crossing the upper surveillance beam.

[Effects of the Invention] As described above, according to the present invention, a fire can be reliably detected because the fire is determined from the rising speed of smoke that crosses the monitoring beams arranged above and below.

In addition, events such as dew condensation or fog that obstruct the monitoring beam do not move from bottom to top, and it is possible to reliably prevent false alarms without judging it as a fire.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention; FIG. 2 is a flow chart showing the fire determination process of FIG. 1; FIG. 3 is a time chart showing an example of the lower and upper light reception outputs of FIG. FIG. 4 is a block diagram of another embodiment of the present invention using a modulation system; FIG. 5 is a block diagram of another embodiment of the present invention in which the wavelengths are different. [Explanation of symbols] 10: Light emitting unit 12: Light receiving unit 14: Receiver 16: Monitoring beam (lower side) 18: Monitoring beam (upper side) 20: Emission drive unit 22-1, 22-2: Light emitting element 24- 1,24-2: Lens 26-1, 26-2: Light receiving element 28: Amplifying section 30: Computing section 32: Judging section 34-1, 34-2: Modulating section 36-1, 36-2: Demodulating section 38 -1,38-2,40-1,40-2: Bandpass filter

Claims (1)

(57) [Claims] 1. A dimming type separated smoke in which a light projecting portion and a light receiving portion are separately arranged, and a change due to invasion of smoke of a monitoring beam projected from the light projecting portion is detected and alarmed on the light receiving portion side. In the sensor, at least two sets of a light emitting part and a light receiving part are vertically arranged at a predetermined interval, and a distinguishable monitoring beam is projected for each set, and a lower side monitor is provided on the light receiving part side. A calculation unit that calculates the rising speed of the object that rises from the time difference between the beam being blocked and the upper monitoring beam being blocked, and a determination unit that determines whether or not there is a fire based on the rising velocity calculated by the calculation unit. A dimming separation type smoke detector characterized by being provided.