Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1997-01-08
1998-09-22
Hannaher, Constantine
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
25033902, 25033904, 250351, G01J 562
Patent
active
058118110
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an environment monitoring technology according to an infrared sensing system and more particularly to a technology useful for a chopping mechanism of an environment monitor, separating an incident infrared radiation into a plurality of wavelength bands, sensing the intensity of an infrared radiation of each separated wavelength band by a sensor, and enabling detection of the temperature and determining whether a disastrous fire occurs or not, in a monitored area, on the basis of the outputs of the sensors.
BACKGROUND ART
As a fire sensing method or an apparatus, for automatically sensing the occurrence of a disastrous fire, for example, an infrared sensing system for sensing infrared radiation from a flame has been known up to this time. In a fire sensing apparatus of such an infrared sensing system, a chopper for periodically chopping an incident infrared radiation is provided in front of an infrared sensor. However, a conventional general chopper entails a drawback in that when there are some temperature differences between the chopper and the background thereof, the sensor produces an output in response to the differences even if there is no heating source in the visual field of the sensor. The present applicant has filed an application (Japanese Patent Application Publication (Laid-Open) No. Tokukai-hei 4-299797) for an invention relating to a chopper in that when there are some temperature differences between the chopper and the background thereof, the sensor does not sense and provides no output.
Although the fire sensing apparatus using a chopper which is described in the above prior application by the present applicant can detect the presence or absence of a disastrous fire when monitoring a relatively wide visual field, it cannot recognize where the disastrous fire occurs in the visual field. When a plurality of disastrous fires occur, it may not to recognize the presence or absence of the disastrous fires due to the mutually interfering inputs to the sensor. For example, when there are two heating sources A and B, and infrared radiation from the heating source A and infrared radiation from the heating source B enter the sensor, and if the directions of these infrared radiations from the heating sources are different from each other, there is a possibility that the timing of the infrared radiation interrupted by the chopper will be different from each other, in particular, there is a possibility that when the infrared radiation from the heating source A is interrupted by the chopper, the infrared radiation from the heating source B reaches to the sensor through a slit (an opening) of the chopper. In this case, the infrared radiation which reaches to the sensor leads to the same result as the infrared radiation not being interrupted by the chopper. Consequently, there is a possibility that the sensor concludes that there is no heating source, although there are two heating sources.
The present invention was developed in view of the above-described problems. An object of the present invention is to provide a technology for sensing a disastrous fire which not only can recognize where the disastrous fire occurs in a wide visual field monitored, but also the separate the visual field.
Another object of the present invention is to be able to detect the presence or absence of a disastrous fire and the occurrence position thereof by changing only a chopper while using a signal processor and a judgment circuit, in a conventional fire sensing apparatus.
DISCLOSURE OF THE INVENTION
In order to achieve the above-described objects, in the present invention, a disc having a plurality of radial slits each of which have approximately the same width as a diameter of a photoreceptor of the sensor, and a rotary chopper, are arranged to coaxially rotate. When one of the slits faces a sensor, the disc and the chopper are rotated at a rotational speed so that the incident infrared radiation into the sensor is chopped 2-16 times, preferably 2-8 times, by the choppe
REFERENCES:
patent: 3641345 (1972-02-01), Coackley et al.
patent: 3926527 (1975-12-01), Pembrook et al.
patent: 4043742 (1977-08-01), Egan et al.
patent: 4693615 (1987-09-01), Kyriakis
patent: 5153563 (1992-10-01), Goto et al.
Hannaher Constantine
Japan Energy Corporation
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