JPH05296934A - Gaseous substance detector - Google Patents

Abstract

PURPOSE:To obtain a gaseous substance detector having excellent response characteristics and high detection sensitivity. CONSTITUTION:The title detector is provided with a tubular substrate 1, reflecting film 2 formed on the internal surface of the substrate 1, functional pigment film 3 formed on the film 2 and composed of a color former film which changes in absorbancy upon absorbing or desorbing a gaseous substance 4 to be detected, and light emitting means 5 which is provided on the outside of one side face of the substrate 1 and generates the incident light of the film 3. In addition, the detector is also provided with a light receiving means 6 which receives the light emitted from the means 5 and reflected by the film 3 and detecting means 13 which detects the absorbancy variation of the film 3 based on the output of the means 6 and detects the substance 4 based on the varying value f the absorbancy. The incident light from the means 5 is multiply reflected in the substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas substance detecting device capable of detecting a gas substance, particularly a gas substance such as an odor substance, by utilizing light.

[0002]

_2. Description of the Related Art Heretofore, as a gas substance detecting device of this type, an oxide semiconductor such as SnO ₂ or ZnO has been used, which is detected from changes in conductivity of the oxide semiconductor due to adsorption / desorption of gas. There is a method in which a thin film such as a polymer is formed on the surface of a crystal oscillator, and the thin film is detected from changes in the oscillation frequency of the crystal oscillator due to adsorption and desorption of gas. However, since these detection devices use electric signals, electric sparks may occur during detection, and it has been difficult to detect those containing flammable gas.

Therefore, recently, a detection method using a functional dye film whose absorption wavelength or absorbance changes due to adsorption and desorption of a gas to be detected has been proposed, which makes it possible to detect a substance containing a flammable gas. Came.

However, this functional dye film has a characteristic that the detection sensitivity depends on the film thickness of the dye film, and as the film thickness increases, the detection sensitivity increases, but the response speed decreases. In time, sensitive gas detection could not be performed.

On the other hand, in Japanese Unexamined Patent Publication No. 2-167449, as shown in FIG. 3, a functional dye film 23 whose absorbance is changed by adsorption and desorption of a gas to be detected 22 is formed on both surfaces of a glass substrate 21, and its formation. The detected gas 22 is brought into contact with both of the functional dye film 23 thus formed, and the light emitting element 2
The light emitted in 4 is incident from one side of the base 21 obliquely, and the change in absorbance of reflected light at this time is detected by the light receiving element 25 to detect and quantify the gas 22 to be detected, and
A detection device has been proposed in which light emitted from the light emitting element 24 is multiply reflected on the functional dye film 23 to amplify the light reflectance and improve the detection sensitivity.

[0006]

However, in this newly proposed detection device, in the case of multiple reflection, a part of the reflected light is refracted in the functional dye film 23, so that the reflected light is attenuated and is sufficiently attenuated. The light reflectance was not amplified and the detection sensitivity could not be improved. Further, in the above-mentioned conventional device, since the light from the light emitting element 24 is multiply reflected on the side surface opposite to the side surface of the functional dye film 23 that comes into contact with the gas to be detected 22, the light is reflected to prevent attenuation of the reflected light. It was not possible to provide a film on the functional dye film 23 due to the constitution.

The present invention has been made in view of the above problems, and provides a gas substance detection device having excellent response characteristics and high detection sensitivity.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a tubular substrate,
One of the tubular substrate, a reflective film formed on the inner surface of the tubular substrate, a functional dye film formed on the reflective film and comprising a color former film whose absorbance changes by adsorption and desorption of a gas substance to be detected. The light emitting means is provided on the outside of the side surface and emits the light incident on the functional dye film, and the other side surface of the tubular substrate is provided on the outside of the side surface, emitted from the light emitting means, and reflected by the functional dye film. A light receiving means for receiving the reflected light thus reflected,
A gas substance detection device comprising: a detection unit that detects a change in absorbance of the functional dye film based on an output of the light receiving unit and detects a gas substance to be detected based on the change value. In the tubular substrate, incident light from the light emitting means is multiply reflected.

[0009]

According to the present invention, since the reflecting film is provided between the tubular substrate and the functional dye film provided on the inner surface thereof, when the incident light is multiply reflected in the functional dye film, The reflected light is not refracted and attenuated in the functional dye film.

Therefore, by multiply reflecting the incident light in the functional dye film, the light reflectance is amplified and the sensitivity of gas substance detection is improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments. FIG. 1 is a schematic cross-sectional view of a main part of a gas substance detection device showing an embodiment of the present invention.

In the figure, 1 is a tubular substrate made of glass, plastic, etc. (tube length 90 mm, inner diameter 20 m)
m) and 2 are reflection films formed on the inner surface of the tubular substrate 1 by vapor deposition or sputtering. The reflective film 2
A thin film of chromium or aluminum having a high reflectance for light in the visible light region (300 nm to 800 nm) is used as the thin film, and the film thickness is set to 1000 Å. Reference numeral 3 is a functional dye film formed on the reflective film 2, and is composed of a color former film whose absorbance changes by adsorption and desorption of the gas substance 4 to be detected.

In this embodiment, as the functional dye film 3,
A crystal violet lactone (hereinafter abbreviated as CV) having a chemical structure shown in [Chemical Formula 1] and a bisphenol A (hereinafter abbreviated as BF) having a chemical structure shown in [Chemical Formula 2] were used as CV: BF = 1. : 2 by weight,
Cellulose acetate is used as a matrix material in a weight ratio of 5 times that of CV, and tetrahydrofuran is used as a solvent.
A color former film made of a triphenylmethanephthalide dye produced by adding 125 times by weight to V was formed on the reflective film 2 by a casting method. The chemical structure of this triphenylmethanephthalide dye is shown in [Chemical Formula 3].

[0014]

[Chemical 1]

[0015]

[Chemical 2]

[0016]

[Chemical 3]

At this time, before the functional dye film 3 is formed on the reflective film 2 by the casting method, the surface of the reflective film 2 is first ultrasonically cleaned with acetone or the like, and then acid cleaning (hydrogen peroxide solution) is performed. Dipped in a mixture of 1: 1 and sulfuric acid),
By removing the organic substance and the inorganic substance on the reflective film 2, the functional dye film 3 is uniformly formed on the reflective film 2. The film thickness of the functional dye film 3 was 1000Å.

Reference numeral 5 denotes a halogen lamp or LED which generates light incident at an incident angle of 75 degrees from one side of the tubular substrate 1.
Reference numeral 6 denotes a light receiving element including a photodiode, a phototransistor and the like for detecting reflected light after the incident light from the light emitting element 5 is multiply reflected in the tubular substrate 1. In this example, the multiple reflections were set to reflect 15 times in the tubular substrate 1.

Next, the detection operation when the gas substance detection device of the present invention is used will be described with reference to FIG. FIG. 2 shows a schematic configuration diagram of the gas substance detection device of the present invention. The same reference numerals as those in FIG. 1 indicate the same components.

In FIG. 2, 11 is a gas inlet for introducing the gas substance 4 to be detected into the tubular substrate 1, 12 is a gas outlet for discharging the gas 4 to be detected from the tubular substrate 1 to the outside of the apparatus,
Reference numeral 13 is a control circuit for controlling on / off of the light emitting element 5 and detecting and quantifying the gas to be detected 4 based on the output of the light receiving element 6, and 14 is a CRT for displaying the output from the control circuit 13.

First, the gas to be detected 4 is introduced into the tubular substrate 1 through the gas introduction port 11 so that the inside of the tubular substrate 1 is in an atmosphere of the gas to be detected 4. Thereafter, the light emitting element 5 is turned on, light is made incident into the tubular substrate 1, and the output of the reflected light after multiple reflection is detected by the light receiving element 6. Next, in the control circuit 13, the change in the absorbance of the functional dye film 3 is detected based on the output value of the light receiving element 6, and the detected gas 4 is detected and quantified based on the change value. It should be noted that the control circuit 13 stores in advance the absorbance characteristic data of five kinds of odorous substances such as ethanol, acetone, ammonia, hydrogen sulfide, and methanol, and the detection target gas 4 is detected and quantified based on the data. ing. Then, the result is displayed on the CRT 14.

As described above, since the reflecting film 2 is provided between the tubular substrate 1 and the functional dye film 3 provided on the inner surface thereof, the incident light is allowed to pass through the functional dye film 3 many times. As a result, the light reflectance is amplified, and the gas to be detected 4 can be detected and quantified with high sensitivity.

Next, multiple reflections (15 times) were performed on the ethanol gas, which is the odorous substance of sake, in the apparatus of FIG. 1 embodiment.
In the dry air, the concentration of ethanol was 0.1%, the concentration of ethanol was 0.01, and the concentration was 0.01.
The results obtained by measuring the absorbance under three kinds of conditions are shown in Table 1. The response time of the measurement was all 2 to 3 seconds.

Here, the absorbance values shown in Table 1 are calculated based on the following equation. Therefore, when the light reflectance is 100%, the absorbance value is 0, and when the light reflectance is 10%, the absorbance value is 1.

The functional dye film 3 changes its physical properties by contact with ethanol gas, and the wavelength at which the light absorption property changes most is 609.1 nm.
The emitted light at 9.1 nm was measured.

[0026]

[Table 1]

[0027]

[Equation 1]

From Table 1, in the case of only single reflection, the absorbance is 0.0901 in dry air and the ethanol concentration is 0.1%.
0.0887, 0.01% ethanol concentration 0.09
00, there is almost no difference in absorbance with respect to dry air under the condition that the ethanol concentration is 0.01%, whereas in the case of multiple reflection, 1.3501 in dry air and 0.1% etal concentration. %, 1.3290, ethanol concentration 0.01
% Is 1.3487, and the ethanol concentration is 0.0
Even under the condition of 1%, the difference in absorbance with respect to that in dry air is 0.0014, which shows that the detection sensitivity is improved.

Further, in the apparatus of FIG. 1 embodiment, the reflection film 2
In the case of multiple reflection (15 times) without providing, the absorbance was measured under the same conditions as above, but the reflected light was refracted into the functional dye film 3 and the emitted light became a minute output,
Absorbance could not be measured.

In the above embodiment, the case where the film thickness of the functional dye film 3 is 1000Å has been described, but other values may be used. However, since the response characteristic of detection depends on the film thickness of the functional dye film 3, the film thickness is 500 to 100.
It is preferable to set it to 0Å. In addition, the number of multiple reflections is 15
Although the case of the number of times is described, the number of times may be other than this, and the number of times may be set appropriately according to the substance 4 to be detected.

Further, in the above embodiment, the case where the functional dye film 3 is composed of the color former film made of triphenylmethanephthalide dye has been described, but other color former films, for example, indolylphthalide dye. The same effect can be obtained even if the color former film is composed of.

[0032]

As described above, according to the present invention, since the reflecting film is provided between the tubular substrate and the functional dye film provided on the inner surface thereof, incident light is multiplexed within the functional dye film. When reflected, the reflected light is not refracted and attenuated in the functional dye film, and as a result, the light reflectance is amplified.

Therefore, it is possible to provide a gas substance detection device in which the sensitivity of gas substance detection is improved without increasing the film thickness of the functional dye film.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a gas substance detection device showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a gas substance detection device showing an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a conventional gas substance detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tubular substrate 2 Reflective film 3 Functional dye film 4 Gas substance to be detected 5 Light emitting element (light emitting means) 6 Light receiving element (light receiving means) 11 Gas introduction port 12 Gas exhaust port 13 Control circuit (detection means) 14 CRT

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Kenichi Shibata 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A functionality comprising a tubular substrate, a reflective film formed on the inner surface of the tubular substrate, and a color former film formed on the reflective film and having an absorbance changing by adsorption and desorption of a gas substance to be detected. A dye film, a light emitting means provided on the outer side of one side surface of the tubular substrate, and emitting light incident on the functional dye film, and a light emitting means provided on the outer side of the other side surface of the tubular substrate, emitted from the light emitting means. A light receiving means for receiving the reflected light reflected by the functional dye film, and a change in absorbance of the functional dye film based on the output of the light receiving means, and a gas to be detected based on the change value. A gas substance detection device comprising: a detection unit that detects a substance, wherein the incident light from the light emission unit is multiply reflected in the tubular substrate. 2. The gas substance detection device according to claim 1, wherein the gas substance to be detected is an odor substance.