JPH076844B2 - Temperature measurement method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for measuring temperature of any object for which image information is obtained and for which temperature measurement is required, for example, the flame temperature of a boiler furnace.

[Conventional technology]

The temperature measurement of a perfect black body by a conventional two-color thermometer of the optical temperature measurement method will be described as an example.

FIG. 5 is a theoretical curve of blackbody radiation according to Planck's equation in which the radiant energy from the blackbody is expressed with respect to wavelength with temperature as a parameter.

Since one equation is determined for each temperature, for example, in this figure, the intersection point G ₁ of the wavelength G with the 700 ° C. curve and the wavelength R
The ratio R ₁ / G ₁ with the intersection R ₁ with 700 ° C., the ratio R ₂ / G ₂ on the 750 ° C. curve, and the ratio R ₃ / G ₃ on the 800 ° C. curve are uniquely determined. Therefore, conversely, the temperature of the object can be measured by measuring the radiant energy of the wavelengths G and R of the object.

This curve is for a perfect black body, but even for a gray body whose emission varies with the magnification of the coefficient ε (0 <ε ≦ 1), if the two wavelengths of R and G are used, the effect of the coefficient ε is affected. The temperature can be measured without. The method of measuring the radiant energy at two wavelengths and obtaining the temperature from the ratio is called a two-color thermometer and is widely used industrially.

FIG. 6 shows the structure of a two-color thermometer.

The light from the measurement object 1 is received by a narrow band filter 2 that allows only the wavelength R to pass and a narrow band filter 3 that allows only the wavelength G to pass, and is passed to a calculation circuit 5 through a photoelectric converter 4 placed behind them. The temperature of the measurement object was calculated and calculated from both input ratios, that is, the two-color ratio.

[Problems to be Solved by the Invention]

The above conventional two-color thermometer is suitable for measuring the temperature of a very narrow portion. For example, when the inside of the boiler furnace was measured by a two-color thermometer, the temperature at a desired point was known, but the entire temperature distribution was not known.

[Means for Solving the Problems]

 The present invention takes the following means in order to solve the above problems.

Of a color television camera aimed at the object to be measured,
Decoder for each color output for each video point R (red), G
Separated into (green) and B (blue) signals, the same R (red), G
Γ inverse correction is applied to the outputs of (green) and B (blue), multiple sets of dichroic ratios such as R / G are calculated, and the theoretical curve of black body radiation with temperature as a parameter is used to analyze the spectrum of a color television camera. A plurality of sets of dichroic ratios of theoretical R (red), G (green) and B (blue) signals obtained in advance by a calibration curve obtained by correcting the characteristics are calculated, and the dichroic ratios of these two sets are used. A temperature measuring method, characterized in that the temperature of the measuring object is calculated for each of the image points.

[Action]

By the above method, the R, G is detected by the decoder for each video point from the signal of the color television camera aimed at the measurement object.
And B signals are calculated, and γ is inversely corrected, then the dichroic ratio is calculated, and the theoretical curves of black body radiation are corrected in advance with the theoretical characteristics of the color characteristics of the color television camera R, G.
And the dichroic ratio of the B signal is calculated, and the temperature for each image point is calculated and output from these two sets of dichroic ratios.

In this way, the temperature distribution of the measurement object can be easily obtained.

〔Example〕

An embodiment to which the method of the present invention is applied will be described with reference to FIGS.

FIG. 1 is a configuration diagram of the same embodiment, FIG. 2 is an explanatory diagram of .gamma. Characteristics of the color television camera of FIG. 1, FIG. 3 is a spectral characteristic diagram of the color television camera of FIG. 1, and FIG. It is explanatory drawing of the correction method by the spectral characteristic of the color television camera of the said Example.

In FIG. 1, an output for each image point of a color television camera (hereinafter abbreviated as a camera) 10 is input to a decoder 11. The R (red), G (green) and B (blue) outputs of the decoder 11 are input to the dichroic ratio temperature calculation means 13 via the γ inverse correction circuit 12. Further, the two-color-ratio temperature calculating means 13 receives the output of the corrected theoretical curve means 14 and calculates and outputs the temperature.

In the above configuration, the camera signal is generally processed according to the NTSC system, which is a standard television system in Japan, and sent to the decoder, where R (red), G (green) and B
The signal decomposed into the three colors of (blue) is extracted.

The cathode ray tube of a television receiver has a characteristic that its output, that is, the brightness of the screen, does not change linearly with respect to its input voltage, as shown in the receiver curve of FIG. Therefore, on the camera side, as shown in the camera curve, the camera side has a characteristic that a voltage larger than the actual voltage is output at the time of a low input so as to complement the receiver curve, and the camera and the image The characteristics of both units work complementarily, and the same brightness as the brightness input to the camera is reproduced on the screen of the receiver.Since this curve pair is similar to the Greek letter γ, this correction is γ correction Say.

Further, since the camera is mainly intended to reproduce and show an image to a human, it has a spectral characteristic close to the luminosity of the human eye as shown in FIG. 3 and selectively selects light of a single wavelength. I'm not supposed to take in.

Therefore, when trying to use the output signal of this camera to measure the temperature, it is said that the energy corresponding to the wavelength width expanded with respect to the R, G signals of the dichroic thermometer is output to the camera. Considering this, the spectral output is placed on the theoretical curve, and the output of the camera is considered as the integral of the incident energy for each wavelength.

Now, in the configuration of FIG. 1, the signal returned to R, G, and B by the γ inverse correction becomes a signal that is faithfully proportional to the input only after the γ inverse correction is provided next. Next, a plurality of sets of dichroic ratios are calculated by the dichroic temperature calculation means, and the calculated dichroic ratios of theoretical outputs obtained from the theoretical curve means with correction, which have been calculated in advance, are collated and the temperatures at the respective image points are calculated as follows. It is calculated from two types of two-color ratio and output.

The calculation method of the above theoretical curve means with correction will be described below.

In FIG. 4, on the black body radiation theoretical curve with the parameter T = T ₀ , for example, the red component output of the camera with the center wavelength R is given by the equation (1), where R is the spectral characteristic of the camera. This is the output of one wavelength in the dichroic method.

S ′ _R = W ₀ · y ₀ + W ₁ · y ₁ + W ₂ · y ₂ …… W _n · y _n・ ・ ・
(1) Further, the theoretical output of the R camera at the final temperature T ₀ is expressed by the equation (2) by multiplying the R peak value on the spectral characteristic.

S ′ _R = C _R S ′ _R (2) As described above, since temperature data for each image point can be easily obtained from the camera signal, the temperature distribution of flames and the like can be grasped and combustion It is extremely useful as a monitoring and control means.

[Effects of the Invention] The present invention has the following effects.

Conventionally, from the signal (video) of the TV color camera that was installed for the purpose of monitoring the flame with human eyes,
By being able to measure temperature data with physical quantification, it is possible to quantitatively grasp combustion, including its distribution, and compare it with other flames, and obtain more accurate combustion monitoring or information as a control sensor. Will be available.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is an explanatory view of .gamma. Characteristics of a conventional color television camera, FIG. 3 is a spectral characteristic of a conventional camera, and FIG. 4 is a theoretical curve means with correction of FIG. Fig. 5 shows the conventional black body radiation theoretical curve, and Fig. 6 shows the principle of the conventional two-color thermometer. In the figure, 1 ... Object to be measured, 2 ... R filter, 3 ... G filter, 4 ... Photoelectric converter, 5 ... Operation circuit, 10 ... Color television camera, 11 ... Decoder, 12 …… γ reverse correction circuit, 13 …… two-color ratio temperature calculation means, 14 …… correction theoretical curve means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukiko Takahira 1-1, Atsunoura Town, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries Ltd. Nagasaki Shipyard (72) Inventor Yasuhiko Sato 1-1, Atsunoura Town, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industry Co., Ltd. Nagasaki Research Institute

Claims (1)

[Claims] 1. A decoder outputs each color output of each image point of a color television camera directed to an object to be measured.
(Red), G (green) and B (blue) signals
The outputs of (red), G (green) and B (blue) are inversely corrected by γ, multiple sets of dichroic ratios such as R / G are calculated, and the theoretical curve of blackbody radiation with temperature as a parameter is colored. Plural sets of dichroic ratios of theoretical R (red), G (green) and B (blue) signals obtained in advance by a calibration curve obtained by correcting the spectral characteristics of the television camera are calculated, and two sets of these two sets are calculated. A temperature measuring method, wherein the temperature of the measuring object is calculated for each of the image points by using a color ratio.