JPH06288858A - Gas visualizer - Google Patents

Abstract

PURPOSE:To obtain a gas visualizer which can monitor over a wide region by appropriately obtaining image information on a situation of gas leaks including backgrounds with a simple configuration. CONSTITUTION:A gas visualizer, comprising an image sensor 4 which detects infrared rays emitted or reflected from the background of a gas leak monitor target region A, a laser light source 3 which two-dimensionally directs detection infrared rays of wavelengths absorbed by a specimen gas g to the gas leak monitor target region A, and a CRT 6 which displays information related with gas leaks as a two-dimensional visualized image with respect to the monitor target region A, is provided in the light source 3 with a beam expander 7 which condenses.enlarges an irradiating infrared flux and changes the area of the irradiation target region and with transmission band changing means 9, 10 which set the band of an infrared flux incident on the image sensor 4 at a band where the wavelength lambda of detection infrared rays is at about the center position and change the width of a band, thereby obtaining an excellent visualized image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a tank in a factory,
The present invention relates to a gas visualization device for detecting a gas to be detected which leaks from a pipe or the like, a buried conduit or an exposed conduit on a road or the like, and an outdoor or indoor piping in a home.
Further, such a gas visualization device is also used for detecting gas leaks and the like that leak during the airtight trial.

[0002]

2. Description of the Related Art Conventionally, in gas leak detection in a factory, a plurality of detection devices are arranged in a monitoring target area to grasp the situation of gas leak. Therefore, in this method, the detection is limited to the detection of the leak point, and therefore, for example, the leak state in a large area in the factory (the amount of the gas to be detected or the position of the leak specific point such as the specific position of the tank or the pipe) is known. In order to do so, it was necessary to install gas leak detection equipment in many places and grasp the leak gas situation. On the other hand, in order to monitor such gas leakage, it has been proposed to irradiate a specific gas leakage monitoring target area with infrared rays and monitor the gas leakage by utilizing the absorption state of the infrared rays by the gas. ing. However, in this case, since the rays used are parallel rays, it is necessary to scan the irradiation rays.

[0003]

Therefore, the inventors of the present invention have devised a gas visualization device for irradiating infrared rays two-dimensionally by the irradiation means, targeting a relatively wide gas leakage monitoring region. However, in such an apparatus, there are disadvantages such that the power consumption for operating the irradiation means becomes large and an expensive and large-sized large power laser is required. Therefore, it would suffice if the infrared rays radiated from the background of the gas leakage monitoring target area are detected as they are, and the state of gas leakage can be displayed on a display device such as a CRT in the form of a grayscale image in the form of a visualized image. In the apparatus having the configuration, the detection signal, which is the gas absorption information with respect to the background signal, is weak, and there is a drawback that the display on the CRT is not properly performed. That is, due to the effects of sunlight, the image may become excessively bright or dark depending on the day or the season,
The resolution of the intensity with respect to the concentration of the gas to be monitored may deteriorate. Therefore, even if an image of the monitoring target area including the background, which includes infrared absorption information due to gas leakage as a dark image signal, the existence of gas cannot be clearly confirmed. In this situation, when the infrared rays emitted from the background are simply detected as described above, the infrared irradiation means is further operated to emit the infrared rays and the infrared rays emitted or reflected from the background are detected. The same thing happens when the above is displayed. Therefore, an object of the present invention is to obtain a gas visualization device capable of monitoring a wide area by appropriately obtaining image information regarding a gas leak situation including a background with a simple device configuration.

[0004]

In order to achieve this object, a gas visualization device according to the present invention comprises infrared plane detecting means for detecting infrared rays radiated or reflected from the background of a gas leak monitoring area. Infrared planar irradiator that two-dimensionally irradiates infrared rays for detection of the wavelength absorbed by the gas to be detected toward the gas leak monitoring target area, and gas leak related information is two-dimensionally visible corresponding to the monitoring target area. An infrared area irradiation means for collecting and enlarging an irradiation infrared ray bundle, and an irradiation area changing means for changing an irradiation target area area), and an infrared area detecting means, The detection target area changing means for changing the detection target area area is provided, and the band of the infrared ray flux incident on the infrared planar detecting means is set to a band having the wavelength λ of the detection infrared light at the approximate center position, and the width of the band is set. A further transmission band changing means is provided, and only the infrared surface detecting means is operated to detect infrared rays emitted from the background of the gas leakage monitoring target area, and the detection information is displayed on the display means as the gas leakage related information. The passive display mode for displaying and the active display mode for displaying the detection information of the infrared planar detection means by operating the infrared planar irradiation means and the infrared planar detection means on the display means as gas leakage related information are displayed. A mode switching unit for switching the mode is provided, and when active monitoring is performed in the active display mode, the transmission band of the transmission band changing unit is set to be narrower than the transmission band of the transmission band changing unit in the passive display mode. In particular, the action and effect are as follows.

[0005]

In the gas visualization device having the above-described structure, the infrared rays transmitted through the gas leakage monitoring target area by the infrared surface detecting means are irrelevant to the background regardless of whether the infrared rays are irradiated or stopped. Dimensionally detected. This detection information includes gas absorption information in the background information. Here, the absorption information of the gas is included in the wavelength signal of the infrared ray for detection in the band absorbed by the gas to be detected, and the information about the background is included in all the wavelength signals detected. Therefore, in this visualization device, the irradiation area changing means and the transmission band changing means are provided so that the ratio of the gas absorption information and the background information is appropriately adjusted and passed to the display means side. Mode switching means is provided so that an appropriate display can be made depending on whether or not there is a gas leak, and in order to prolong the life of the device. There is. Further, the detection target area changing means is provided so that the monitoring when the gas leakage occurs can be concentrated at a specific portion. The respective functions will be described below.

First, the transmission band changing means will be described. The transmission bandwidth changing means changes the transmission bandwidth of the signal passed to the detecting means. Naturally, the wavelength of the infrared ray for detection is included in this band. Here, if the transmission bandwidth is changed, the amount of information regarding the gas absorption detected on the detection side remains unchanged, and the amount of information regarding the background changes. Generally, on the display means side, normalization processing (the total amount of information processed on the display means side is made constant) is performed, but in the apparatus of the present application, even in the state where this normalization processing is performed, By adjusting the transmission bandwidth, the ratio of the background information to the gas absorption information can be adjusted to an appropriate value, and a good visualized image can be obtained on the display means. Here, a general TV device is equipped with a gain adjusting device (not shown), but changing the transmission bandwidth is more effective than adjusting the gain adjusting device in terms of adjusting the S / N ratio of the visualized image. Thus, the display state can be favorably optimized. 5 and 6 each show the relationship between the detected wavelength and each wavelength component in the spontaneous emission state and the infrared emission state (when the transmission band is not adjusted (a) and when the transmission bandwidth is limited ( The signal state of b) is shown, the broken line shows the state when no gas leakage occurs, and the solid line shows the state where gas leakage occurs and infrared absorption occurs.) The shaded area indicates the gas absorption area. That is, as is clear from the figure, the information amount related to the gas absorption amount (information mainly included in the area below the shaded area in the figure) and the total detected information amount (solid line in the entire wavelength range in the figure By changing the ratio with respect to the information contained in the lower region) in (a) and (b), the S / N ratio is adjusted to a ratio suitable for display.

The above-mentioned transmission band changing means works effectively regardless of the operation / stop of the infrared irradiating means, but the irradiation area changing means works effectively when the infrared irradiating means operates. That is, the irradiation area changing means can change the area area of the infrared ray for detection to be irradiated. Therefore, when the area to be monitored by the detection means is constant, the ratio of the background information to the gas absorption information changes according to the same principle as described above by changing the area area. You can get it. Furthermore, when the detection infrared rays are irradiated with a large viewing angle so as to cover a relatively wide area, a relatively high concentration gas area is displayed on the display means, and the irradiation area changing means converges on a certain area. Then, when the infrared rays for detection are irradiated, the contrast is displayed even in a gas region having a relatively low concentration. FIG. 7 shows the detection limits of gas concentration in the case of wide area irradiation and the case of narrow area irradiation.

Next, the mode switching means will be described. In the passive display mode, infrared rays emitted from the background of the gas leak monitoring target area (for example, gas related facilities such as gas spherical holders and natural objects such as trees) are detected only by the infrared planar detection means, and gas leakage is detected. The situation of is roughly grasped. Then, when there is a danger due to the monitoring condition of the gas leak with rough accuracy, the mode switching means is activated to set the active display mode. In this mode, it is possible to irradiate infrared rays for detection and perform more accurate gas leak determination based on the intensity of infrared rays reflected from the background. Here, in both modes, the ratio of the information on the gas concentration on the detection infrared rays and the information contained in the entire wavelength region detected by the detection means naturally needs to be adjusted before the delivery to the display means. is there. This adjustment is performed by the transmission band setting means in the active display mode,
This is possible by setting the transmission band to be narrower than the transmission band in the passive display mode.

Further, the area-to-be-detected changing means can limit the monitoring in the active display mode, for example, to a problem area by making the area of the detection area by the detecting means variable.

[0010]

In such a gas visualization device, the information including the background information and the gas absorption information can be appropriately displayed on the display means by providing the transmission band changing means and the irradiation area changing means. Since they can be handled simultaneously in a state, the device configuration is simple and the detection system configuration is very simple. Therefore, it is easy to use,
It was possible to provide an inexpensive gas visualization device. Further, when the gas visualization device of the present application is adopted, it is possible to instantly specify the leak location of the gas to be detected that has leaked from a remote location, so that the cause of the leak can be elucidated and maintenance measures can be taken promptly.

[0011]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows a state in which a gas visualization device 1 of the present application is used to monitor gas leakage in the vicinity of a spherical holder 2 (a flange connection portion 2a of a pipe connected to the spherical holder 2) in a gas manufacturing factory. It is shown. That is, the presence or absence of leakage of the flammable gas g as the gas to be detected is monitored in the monitoring area with the spherical holder 2 as an example of the gas leakage monitoring target area A in the background. First, a description will be given of the selection situation and measurement principle of the wavelength λ of the infrared ray for detection in the gas visualization device 1 of the present application. The specific infrared ray propagating in the gas is absorbed by the combustible gas (gas to be detected g). This relationship shows that the intensities of incident light and transmitted light are respectively I
Given by i and Io, it is expressed by the following equation. Io = Ii · exp [−α (λ) × l × c] (Lambert-Beer's formula) where α (λ) is an absorption coefficient determined by the type of gas and the wavelength of infrared rays. l and c represent the length of the interaction between the infrared ray and the gas and the gas concentration. Therefore, the gas to be detected g on the optical path
If there is, this infrared ray is absorbed and its intensity becomes weak. When this is detected two-dimensionally and displayed two-dimensionally on a CRT or the like, it is displayed as a two-dimensional grayscale image, so that it becomes possible to clarify the distribution of the gas g to be detected in the gas leakage monitoring region. . Now, the inventors have investigated the absorption characteristics of methane, propane and butane as the gas to be detected g, and have confirmed that they have a common absorption wavelength in the 3 μm band. That is, a He-Ne laser (oscillation wavelength 3.
Table 1 shows the results of experimentally obtaining the absorption coefficient for each gas when 39 μm) was used as the light source.

[0012]

[Table 1]

From the above, if a He-Ne laser is used as a light source, visualization of methane, propane and butane using infrared absorption can be realized simultaneously with the above-mentioned structure. For example, in LNG terminals, propane, butane, etc. are used for increasing heat in addition to methane, so that it is a major feature in terms of equipment cost that these same leak gases can be monitored. The detailed configuration of the gas visualization device 1 of the present application will be described with reference to FIG. This gas visualization device 1
Is an infrared ray irradiating means for irradiating the gas leakage monitoring target area A two-dimensionally with a detection infrared ray having a wavelength absorbed by a combustible gas g such as methane, propane or butane which is a monitoring target gas. A laser 3 (laser light source is 3a) and an image sensor 4 as infrared plane detecting means for detecting infrared rays transmitted through the monitored area A and radiated or reflected from the background.
It is configured with. Further, a calculation processing means 5 for calculating and processing the detection information from the image sensor 4 is provided, and CR, which is a display means for displaying the information related to the gas leakage after the processing as a two-dimensional visible image.
T6 is provided. That is, by adopting this configuration, the detection information detected by the image sensor 4 is arithmetically processed, and the CRT 6 is provided as the gas leakage related information.
Will be displayed on the screen and will be used for the monitoring work of the monitor. FIG. 3 shows the display status of the CRT 6.

In the gas visualization device 1 of the present application, only the image sensor 4 is operated to detect infrared rays emitted from the background of the gas leak monitoring target area A, and the detection information is used as the gas leak related information. A passive monitor mode displayed on the CRT 6 (display mode in this state is referred to as a passive display mode), the infrared laser 3 and the image sensor 4 are operated, and the detection information thereof is displayed on the CRT 6 as gas leakage related information. The operation mode is selectable between the monitoring mode (the display mode in this state is called the active display mode). The difference between the monitoring target areas in these two modes is shown in FIG.

The problem of the gas visualization device having this structure is to improve the output of the infrared laser 3 and the sensitivity of the image sensor 4. In this device, the beam extractor as the irradiation area changing means described below is used. This is solved by adopting a panda 7, a zoom mechanism 8 as a detection target area changing means, a transmission band changing means including a band pass filter 9 and a switching mechanism 10.

The configuration of each device will be sequentially described below.

The image sensor 4 is emitted from a gas-related facility such as the spherical holder 2 which is the background of the gas leakage monitoring area A or a natural object such as a tree, or is reflected from infrared rays for detection emitted by the infrared laser 3. In addition, the infrared rays for detecting the infrared rays for detection which have passed through the gas leakage monitoring target area A and the infrared rays in the band including the wavelength of the infrared rays for detection are detected. This is used in both the passive monitor mode and the active monitor mode described above. The transmission band width changing means including the plurality of band pass filters 9 and the switching mechanism 10 peculiar to the present application are provided, and the zoom mechanism 8 is provided. An image when the zoom mechanism 8 is operated is shown in FIG. 4b. here,
In the passive monitoring mode, the image sensor 4 can use the infrared radiated light of the background material according to Planck's radiation law as a light source when the infrared absorption spectrum width of the monitored gas is sufficiently wide. Then, the bandpass filter 9 described above is arranged in front of the image sensor 4, and the S / N ratio of the signal (the intensity of the infrared ray for detection which mainly represents the gas concentration is S and the detection which mainly represents the background is performed). A signal having a wavelength other than the wavelength of the infrared light for use is designated as N). Therefore, the bandpass filter 9
The transmission bandwidth (half-value width) of the transmission wavelength that is incident on the image sensor 4 after passing through is selected such that a sufficient amount of light is obtained for the image sensor 4 and the S / N ratio for gas detection is high. Furthermore, the principle of selection and installation of the bandpass filter 9 described above will be described in detail. In the case where a single bandpass filter 9 is used regardless of the passive monitor mode or the active monitor mode, the CRT 6
The display screen in the section becomes excessively bright or dark due to the influence of sunlight. Furthermore, with the same brightness, CRT6
Even in the situation where the image is displayed above, there is a problem that the difference in brightness on the CRT screen with respect to the concentration of the gas to be monitored is low, and even if it is displayed, the presence of gas cannot be clearly visually confirmed. In order to solve such a problem, as the bandpass filter 9, the heat radiation light of the background and the daylight sun reflected light energy are sufficient as compared with the sensitivity of the infrared image sensor, and the gas to be detected is absorbed. The one having a half value width capable of obtaining the S / N ratio of the quantity should be selected, but it is difficult to make the half value width constant because the fluctuation of the solar energy is large. So C
In order to adjust the display on the RT6 to have an appropriate brightness and to provide a good contrast, a bandpass filter 9 is provided by including a transmission band changing means and taking into consideration the fluctuation of the heat radiation of the sunlight and the background. The half-width of the pass filter 9 is variable.

Further, when the detected gas g is visualized,
If the amount of leaked gas is small, the image size of the gas may be small. In such a case, local confirmation by zooming up is necessary, and conversely, if the amount of leakage is large, local monitoring cannot cope. Therefore, the image sensor 4
A zoom mechanism 8 is provided on the light-receiving side of, and the viewing angle of monitoring is variable.

Further, the accumulation time of the image sensor 4 is used for adjusting the sensitivity of the sensor. In particular, when the transmission band of the bandpass filter 9 is narrowed in order to improve the S / N ratio, the amount of light detected by the sensor may be insufficient and sufficient screen brightness may not be obtained. In that case, the brightness of the image is secured by increasing the accumulation time within a range where the screen brightness is not saturated. That is, the image sensor 4 is provided with the storage time control means 4a.

The irradiation side of infrared rays for detection will be described below. This system is equipped with an infrared laser 3 as an infrared plane irradiation means and a beam expander 7 as an irradiation area changing means. The infrared laser 3 is the detected gas g
The one whose wavelength matches the wavelength absorbed by (infrared for detection) is selected, and the laser output is the background reflected energy by the laser when the laser is expanded to the area A to be monitored. It is decided not to be smaller than the sum of energy and background reflected energy from daylight. That is, it is configured such that a sufficient amount of infrared rays for detection can be secured in the daytime as well as at night. Furthermore, in order to avoid the situation where the infrared rays for detection are relatively difficult to detect due to the influence of the background and the sun being too large, it is possible to change the laser expansion range for the purpose of changing the laser reflected light intensity per unit area. A beam expander 7 is provided. The beam expander 7 is usually designed to produce parallel rays, but since diffused light is sufficient in this system, it does not require so much accuracy.
It can be cheap. Since the monitoring range of the image sensor 4 changes depending on the distance, when the infrared laser 3 is parallel light and the distance to the background increases, the monitoring area in the active monitoring state on the monitoring screen becomes narrow and the recognizability deteriorates. Therefore, the enlargement angle is variable within a range smaller than the viewing angle of the image sensor 4. Also, in this system, the laser may be multimode oscillating. That is, the wavelength is 3.39 μm
Lasers have a multimode emission band of 300 MHz
Since it is a narrow band, the laser light included in the absorption band of methane and obtained by multimode oscillation can be used as it is by expanding it with a beam expander. Therefore, it is not necessary to make the laser light containing a large number of wavelengths obtained by multimode oscillation into a single wavelength by a filter as in a normal laser oscillator, and as a result, the laser output can be increased. Further, a pulse laser may be used as long as it can be synchronized with the response speed of the image sensor 4.

The formation of a grayscale image displayed on the CRT 6 will be described below. As I've explained so far, C
The image displayed on the RT 6 is information in which both the image information of the background of the monitoring target area A and the information image of the leak state of the detected gas g are mixed. Then, when the gas to be detected g is present in the gas leakage monitoring target area A, the infrared rays for detection are absorbed in the gas g in the forward path (only in the active monitoring mode) and the backward path, and the gas g concentration is different depending on the location. Due to the difference, a spatial density difference (at different positions in the case of a two-dimensional mapping) is generated in the infrared rays for detection, and this received light information is displayed on the CRT 6 as a grayscale image whose background information is ground in the apparatus of the present application. To be done. Therefore, the operator visually checks the background of the monitored area and the distribution of gas g by CR.
It can be confirmed at T6. Furthermore, since the background is generally stationary and the gas to be detected flows, it is possible to automatically detect a gas leak by comparing image information at different times.

The gas leak determination means 12, the mode switching means 12a, and the infrared irradiation control means 13 provided in the gas visualization device 1 of the present application will be described below. These means 12, 12a and 13 are provided together with the arithmetic processing means 5. The gas leak determination means 12 includes a processing system that compares the detection information at each setting time point to determine the presence or absence of gas leak. That is, in such a place where gas monitoring is required, the background is generally stationary, whereas the leaked detected gas g flows. Therefore, the state of gas leakage is grasped by comparing the image information at different times between the images. This situation (the gas distributions at different times are double displayed) is shown in FIG. 3 above.

The mode switching means 12a, when the above-mentioned gas leak judging means 12 judges that there is a gas leak,
Controls switching from passive monitoring mode to active monitoring mode. That is, the infrared irradiation control means 13
Is operated to operate the infrared laser 3, and the transmission band changing means 9 and 10 are operated to change the transmission band and narrow the irradiation area by the beam expander 7 to centrally monitor a specific gas leak location. Comparing the detection status in passive monitoring mode and active monitoring mode,
In the passive monitoring mode, since the truly necessary infrared intensity signal detected by the image sensor 4 is mainly background information, the bandpass filter 9 having a wider detection wavelength band is selected. It On the other hand, when an infrared ray for detection with a large amount of energy reflected from the background is detected in the active monitoring mode for a processing system that is normalized to express light and shade in the passive monitoring mode, the intensity signal near the detection wavelength is It becomes saturated above a certain value and the shade cannot be discerned. Therefore, when the infrared laser 3 is operated by setting the band-pass filter 9 having a wide band to a state where the S / N ratio is lowered by the control of the mode switching unit 12a described above, the transmission band changing unit 9, The band-pass filter 9 having a narrow band is switched by 10 to increase the S / N ratio in order to detect in detail how much gas leakage is occurring. The change status of the transmission band is shown in FIGS.

The specifications of each element in the gas visualization device 1 described above are listed. Infrared laser 3 Laser type helium-neon laser Nominal output 8 mW Center wavelength λ 3.39 μm, Width of bandpass filter 9 a + b 0.1 to 2 μm where a and b are arbitrarily set. Example of a + b Daylight under sunlight irradiation, active method, target gas; methane a + b 0.1 to 0.2 μm Daylight under sunlight irradiation, passive method, target gas; propane, butane a + b 1 μm nighttime passive method, target gas Propane, butane a + b 2 μm Viewing angle Viewing angle of image sensor Distance to background Several m to several 100 m Image sensor 4 Detection wavelength range 3 μm to 5 μm Maximum detection temperature difference 0.15 ° C. or less (NET
D)

The operation of the gas visualization device 1 of the present application will be described below. (1) Passive monitoring state Infrared rays (radiant heat) radiated from the background of the gas leak monitoring target area A are detected by the image sensor 4, and the presence or absence of gas leak is roughly determined by the gas leak determination means 12.
In this state, in order to improve the S / N ratio, the half-width of the bandpass filter 9 is manipulated so that the background has a light amount that can be confirmed with the minimum brightness necessary for monitoring. At this time, the transmission band of the bandpass filter is selected relatively wide. (2) If there is a gas leak, the gas leak determination means 12 uses the fact that the region where the infrared ray of a specific wavelength is absorbed moves temporally to detect the infrared ray of a specific wavelength. When the absorption region moves two-dimensionally, it is determined that gas leakage has occurred. (3) When the gas leakage determination means 12 determines that the gas leakage occurs with a rough accuracy, the infrared irradiation control means 13
The infrared laser 3 is operated so as to irradiate the infrared ray for detection toward the background and enable more accurate gas leak determination based on the intensity of the infrared ray reflected from the background. At this time, the transmission band is narrowed down by the automatic adjustment of the beam expander 7 and the transmission band changing means 9 and 10, and the CRT is
In the state where the S / N ratio is high, an image signal is sent to S6, and reliable visualization information is obtained and displayed on the CRT 6.

[Other Embodiments] Other embodiments of the present application are listed below. (A) In the above-mentioned embodiment, the infrared ray for detection irradiated by the infrared laser 4 is a single light, and the infrared ray for detection has a wavelength which is absorbed by the flammable gas g. Along with the infrared ray for detecting the wavelength, an irradiation system by a reference infrared ray having a wavelength that is difficult to be absorbed by the gas g (reference numeral 30 is a reference infrared ray irradiation control means indicated by a broken line in FIG. 2 and 3b is a laser light source of the reference infrared ray). These are collectively referred to as the reference infrared surface irradiation means 31) and are provided in addition to the detection system of the above-mentioned embodiment, and the information by the infrared ray of the wavelength not absorbed by the gas is used as the reference information, and the pixel by the absorbed wavelength is used. If the information of is gas leak information,
It is also possible to detect the gas concentration. That is, the reference absorption information is obtained from the logarithm of the ratio of the transmission intensity and the reception intensity of the reference infrared ray according to the Lambert-Beer equation, and the absorption information is similarly obtained from the logarithm of the transmission intensity and the reception intensity of the detection infrared ray. The gas concentration calculation means 50 for deriving the difference between the absorption information and the reference absorption information as the detected gas concentration information may be provided, and the detected gas concentration information may be displayed on the CRT 6 as the gas leakage related information. In this case, it is possible to determine the gas concentration. (B) In addition to the configuration described above, the gas leak determination means 12 may determine the presence or absence of gas leak based on the intensity of the infrared ray for detection of the wavelength absorbed by the gas to be detected g based on the detection information of the image sensor 4. Good. That is, the gas leak determination means 12
Of the absorption information at each detection point on the two-dimensional area corresponding to the monitoring target area A to be detected by the image sensor 4 is a predetermined threshold value (for example, a value representative of the shadow in the normal state is used as the threshold value). If there is a region with a higher gas concentration, it may be determined that gas leakage has occurred. (C) Further, the background of the monitored area may be the ground, concrete wall, painted steel structure, etc., in addition to the spherical holder 2, and a screen may be provided for a specific area.

(D) Further, when the monitored area is wide,
It is also possible to monitor by moving the irradiation area of the laser light with respect to the monitoring target area.

In the above embodiment, the laser oscillator is used as the infrared irradiating means, but the light source is not limited to the laser oscillator.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a usage state of a gas visualization device.

FIG. 2 is a diagram showing a device configuration of a gas visualization device.

FIG. 3 is a diagram showing a display state of leaked gas on a display device with the passage of time.

FIG. 4 is a diagram showing an image of a passive / active monitoring situation and an image when zooming up.

FIG. 5 is a diagram showing a situation of detection information in a spontaneous emission state.

FIG. 6 is a diagram showing a situation of detection information in an infrared irradiation state.

FIG. 7 is an explanatory diagram showing a concentration detection limit due to a change in irradiation area.

[Explanation of symbols]

 3 Infrared surface irradiation means 4 Infrared surface detection means 6 Display means 7 Irradiation area changing means 8 Detection target area changing means 9 Transmission band changing means 10 Transmission band changing means 12 Gas leak determination means 31 Reference infrared surface irradiation means 50 Gas Concentration calculation means A Gas leak monitoring target area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Nishio 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd.

Claims (3)

[Claims] 1. An infrared planar detection means (4) for detecting infrared rays radiated or reflected from the background of the gas leak monitoring target area (A), and an object to be detected toward the gas leak monitoring target area (A). Infrared planar irradiation means (3) for two-dimensionally irradiating infrared rays for detection of wavelengths absorbed by the gas (g) and the gas leakage monitoring target area (A) are used to provide two pieces of gas leakage related information. A display means (6) for displaying as a three-dimensional visible image, and an irradiation area changing means (7) for changing the irradiation target area area by converging and enlarging the irradiation infrared ray bundle on the infrared surface irradiation means (3). In addition, the infrared planar detecting means (4) is provided with a detection target area changing means (8) for changing a detection target area area, and a band of an infrared flux incident on the infrared planar detecting means (4) is , About the infrared wavelength for detection (λ) Transmission band changing means (9) (10) for setting the band to be positioned and changing the width of the band are provided, and only the infrared surface state detecting means (4) is operated to operate the gas leakage monitoring target area. A passive display mode in which infrared rays radiated from the background of (A) are detected and the detection information is displayed on the display means (6) as the gas leakage related information;
By operating the infrared planar irradiation means (3) and the infrared planar detecting means (4), the infrared planar detecting means (4).
When the active monitoring is performed in the active display mode, the detection information of No. 1 is displayed on the display unit (6) as the gas leakage related information, and the mode switching unit (12a) for switching the display mode is provided. A gas visualization device for setting the transmission band of the transmission band changing means (9) (10) to be narrower than the transmission band of the transmission band changing means (9) (10) in the passive display mode. 2. A gas leak judging means (12) for judging the occurrence of a gas leak based on the detection information detected by the infrared surface detecting means (4) is provided, and in the normal monitoring state, The display is performed in a passive display mode, and when the gas leak determination means (12) determines that there is a gas leak, the mode switching means (12a) automatically sets the display mode to the active display mode. The gas visualization device described. 3. A reference infrared planar irradiation means (2) for two-dimensionally irradiating a reference infrared ray having a wavelength that is difficult to be absorbed by the gas to be detected (g) toward the gas leak monitoring target area (A).
1), the reference absorption information is obtained from the relationship between the transmission intensity and the reception intensity of the reference infrared ray, the absorption information is obtained from the relationship between the transmission intensity and the reception intensity of the detection infrared ray, and the absorption information and the reference absorption are obtained. The gas concentration calculation means (50) for deriving a difference from the information as the detected gas concentration information, and the detected gas concentration information as the gas leakage related information is displayed on the display means (6). The gas visualization device described.