JPH0473084B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disaster prevention detection device that detects physical quantities such as smoke and temperature that occur or rise due to a fire.

Traditionally, fire alarm equipment uses ionization smoke detectors, photoelectric smoke detectors, or temperature detectors.
Furthermore, a large number of detection devices are used in various disaster prevention equipment, such as gas leak detectors in gas leak alarm equipment and photoelectric intruder detectors in burglar alarm equipment.
False alarms due to changes in these disaster prevention detection devices over time have become a major problem. Taking photoelectric smoke detectors for fire alarm equipment as an example, most of the causes of this change over time are due to contamination of the detection part. However, the extent to which false alarms occur due to contamination of the detection section is greatly influenced by the structure of the detection section. In the case of a scattered light smoke detector in which the detection chamber DH into which smoke enters is located below, dust J is more likely to accumulate on the wall W of the detection chamber DH than on the optical system. , as shown in the temporal characteristics of the detection signal S in Fig. 2, the increase in scattered light due to this dust J is the cause of false alarms, whereas in the detection chamber as shown in Fig. 3,
In the case of a transmitted light type smoke detector in which a light source LD and a light receiving element PD are arranged facing each other in the DH, the fourth
As shown in the temporal characteristics of the detection signal S in the figure, the light is attenuated by the dust J deposited on the optical system,
This causes false alarms. As described above, even if a single photoelectric smoke detector is used, its characteristics change over time in various ways.

Therefore, as a conventional countermeasure, the standby area consisting of the band in which the detection signal before an alarm can fluctuate is divided into two, a normal standby area and an abnormal standby area, and this abnormal standby area is provided on the alarm side. A system has been proposed in which an advance warning signal is obtained when the detection signal output reaches this range. When this advance warning signal is generated, measures such as removing accumulated dust are taken.

However, even if the above-mentioned measures are taken, the user still suffers from the frequent occurrence of advance warning signals.
This is because, in order to obtain an accurate advance signal before the detection signal enters the alarm range, the abnormal standby range must have a sufficient width, which is easily affected by fluctuations in the normal detection signal. Because it will be. This situation is explained in FIG. 5, which is a part of FIG. 2 enlarged on the time axis. In other words, the detection signal output of a scattered light smoke detector of the type shown in Figure 1 installed in a certain office in one day is around 10 o'clock when the most office workers gather and the smoke from smoking is full. The peak is between 2:00 PM and 4:00 PM, and the lowest is around 2:00 PM. In this way, the value of the detection signal output fluctuates greatly even over a short period of one day, and as mentioned above, it is difficult to issue an advance warning just because the detection signal has entered the abnormal standby area. If they had issued a warning, they would now be troubled by the frequent occurrence of this warning.

As a way to further solve this problem, it is possible to determine whether the detection signal output is in the abnormal standby region at the time when the smoke or dust in the office is at its lowest, for example around 2 a.m. in the case of Figure 5. It is also conceivable to set the time at which the judgment is to be made. However, this pattern of change in the detection signal output is not constant, and there is no guarantee that it will always reach the minimum at a fixed time.

Therefore, in the disaster prevention detection device according to the present invention,
Comparison means for generating an abnormality occurrence signal indicating that an abnormality has occurred in the detection section when the input signal is located in an abnormality standby area set between the alarm area and the normal standby area, The signal holding means is provided with a signal holding means that always replaces the current holding signal with a new holding signal only when the signal is closer to the normal standby range, and an initialization means that initializes this signal holding means. After outputting the holding signal to the comparison means, the initialization means is activated, so that no matter what change pattern the detection signal takes, the true normal value of the detection signal can be surely captured. This will be described in detail below based on the drawings.

Hereinafter, as the disaster prevention equipment to which the present invention is applied, we have selected disaster prevention equipment using a polling method using computer processing, which has been attracting attention in recent years, but of course the scope of application of this occurrence is not limited by this.

Now, what is shown in FIG. 6 is a schematic configuration diagram of a disaster prevention monitoring and control device to which the disaster prevention detection device of the present invention is applied.
, a plurality of detection units D1 _{to N} are connected in parallel via respective transmission units DN. The central unit CT has
Centered around the central processing unit CPU, an input operation section K, a display section DP, and a transmission section DNC are provided via a storage device M and interfaces I ₁ and I ₂ , and this transmission section DNC is connected to the line I. It is connected. In the storage device M, various processing procedures of the entire device are registered, and a buffer is prepared in which at least the detection signals of each detection section are registered. For convenience of explanation, the detection section D is assumed to be a scattered light type smoke detection section as shown in Fig. 1, and includes at least a circuit that converts an analog signal obtained from the detection section into a digital signal, and a circuit that converts an analog signal obtained from the detection section into a digital signal, and a circuit that converts an analog signal obtained from the detection section into a digital signal. It is assumed that the device has an address detection circuit that compares an incoming address signal with its own address and detects its own address.

In the disaster prevention monitoring and control device configured as described above, the central processing unit CPU sequentially transmits each detected data to the transmission unit DNC via the interface _I2 according to the processing means registered in advance in the storage device M. Department
Set the addresses of D _{1 to N} and send out address signals to call each detection unit D _{1 to N.} On the detection section D side, this address signal sent via the line 1 is taken into the address detection circuit via the transmission section DN, and if it matches the own address, a detection output is generated. This detection output activates a circuit that converts the analog signal obtained from the detection section into a digital signal, and sends the detection signal converted to a digital signal to the central device CT.

Now, the central processing unit performs many processes, including fire monitoring processing, which is its original purpose, based on the detection signals of each detection unit D _{1 to} D N obtained as described above. Only the processing part for determining whether or not the detection signal is in the abnormality standby area, which is the object of the invention, will be explained with reference to the flowcharts of FIGS. 7 and 8.

FIG. 7 is an extraction of only the part related to the present invention in the main routine that performs normal processing, and the latest detection signal obtained as described above in step 71 is detected by the polling in the previous figure. It is determined whether the detected signal is smaller than the detected signal obtained at the time. If it is smaller, the detection signal is closer to the normal standby area, so in step 72, this signal is sent to the holding signal buffer in which the detection signal closest to the normal standby area corresponding to the detection section number currently being processed is registered. Update registration and keep the signal. In this way, the processing in steps 71 and 72 forms a signal holding means that uses the detection signal closest to the normal standby area as the holding signal at any time. Note that the determination in step 71 was a process of selecting signals smaller than the previous detection signal, but this naturally applies to signals whose characteristics tend to attenuate over time as shown in FIG. Select and process signals that are larger than the previous detection signal. Further, this signal holding means can also be realized by a simple circuit configuration as shown in FIG. In other words, a capacitor C, a forward diode DI, and resistors R ₁ and R ₂ are connected between the positive and negative power supply terminals.
A normally open contact SW as initialization means, which will be described later, is provided in parallel with the capacitor C. Then, a detection signal is input to the connection point between the resistors R ₁ and R ₂ , and a holding signal is obtained as an output from the connection point between the capacitor C and the diode DI. With this configuration, the capacitor C is charged by the potential difference corresponding to the difference voltage between the power supply voltage and the input voltage of the detection signal, and when the input voltage decreases, it is further charged by that amount, and when the input voltage increases, In this case, charging is blocked by the diode DI, resulting in a structure in which the charged charge is retained. As a result, the detection signal closest to the normal standby range can be obtained from the output terminal as the holding signal at any time.
Note that by closing the normally open contact SW, the charge in the capacitor C is discharged and initialization is performed.

Now, the process shown in FIG. 7 is performed for all the detection sections, and the detection signal closest to the normal standby range of the detection signals from each detection section is registered as a holding signal. The process shown in FIG. 8 is a process for determining whether or not each detection unit has been in a normal standby state from the previous process to the present time based on this holding signal. This may be done automatically using a timer that can be set for a long period of time, such as one week, which is not affected by short-term fluctuations such as smoke caused by smoking. This may be done manually on a regular basis.
When the process starts, first in step 81, the number K of the detecting section D to be processed is set to 1. Next, in step 82, the detection unit with the set number K=1 registered in the holding signal buffer is
The holding signal of _D1 is compared with a preset boundary signal between the normal standby area and the abnormal standby area, and it is determined whether or not it is still smaller than the boundary signal without inverting from the normal standby area. If the result is small, step 83
Then, the holding signal of the detection unit _D1 with the set number K=1 is initialized for the next monitoring period.
However, if the result is large, proceed to step 84 and store the number of this detection unit, its maintenance signal value, processing time, etc. as data during maintenance work, and display it on the display unit DP as necessary. Proceed to step 83. When the initialization is completed in step 83, the number K=2 of the detection section D to be processed next is set in step 85. and,
It is determined in step 86 whether or not this set number K is greater than the final number N of the detection section D. If the result is not large, return to step 82,
Thereafter, the same process is repeated until the final number N is reached. However, if the result is large, it means that the processing has been completed for all the signals held by the detection section D, and therefore the processing is ended. Then, based on the records or displays obtained in this way, measures such as cleaning the corresponding detection section are taken.

As described above, according to the detection device according to the present invention, only the detection signal closest to the normal standby area within the period can be detected, so no matter what pattern the detection signal changes within the period, the state of the detection unit can be reliably detected. It is possible to understand the situation and take appropriate measures such as cleaning. Further, the present invention can be implemented regardless of the temporal characteristics of the detection signal, and is therefore extremely useful for disaster prevention equipment.

[Brief explanation of the drawing]

Figures 1 and 3 are schematic vertical cross-sectional views of different structures of photoelectric smoke detectors, Figures 2 and 4 are time-dependent characteristic curves of the respective detection signals, and Figure 5 is a diagram of the respective detection signal characteristics over time. 2 is a partial characteristic curve enlarged on the time axis, FIG. 6 is a schematic configuration diagram of a disaster prevention monitoring and control device to which the disaster prevention detection device according to the present invention is applied, and FIG. 7 and FIG. FIG. 9, a flowchart used to explain the operation of the detection device, is a circuit diagram in which the signal holding means and initialization means of the disaster prevention detection device according to the present invention are realized by a circuit configuration. D _1~N ...Detection unit, CPU...Central processing unit, M
...Storage device, DP...Display section.

Claims (1)

[Claims] 1. In a disaster prevention detection device that generates an alarm signal when a detection signal of smoke, temperature, etc. is located in an alarm region, an abnormal standby state in which the input signal is set between the alarm region and the normal standby region. a comparison means that generates an abnormality occurrence signal as an abnormality occurrence in the detection section when the detection section is located in the normal standby range; and an initialization means for initializing the signal holding means, and after periodically outputting the holding signal of the signal holding means to the comparison means, the initialization is performed. A disaster prevention detection device characterized by activating a means.