JPH02296185A - Visibility meter calibrator - Google Patents

Abstract

PURPOSE:To calibrate a visibility meter at a low cost and easily by attaching or detaching a plurality of visibility adjusting means arranged in front of an indicator body to reconstruct a specified visible condition. CONSTITUTION:Under a specified visible condition reproduced by attaching or detaching visibility adjusting means 7 arranged in front of an indicator 5 for calibration, brightness of light density detection areas 6a and 6b of an indica tor body 6 is detected with respective spot brightness meters of a light density detection means 8 through the means 7 at a specified distance D and converted 6 into digital from analog to be inputted into a processing means 10. Then, a lightness data of the areas 6a and 6b inputted into the means 10 is read to determine a light contrast of the indicator 5 at the specified distance D and based on the results and a light contrast when the body 6 is viewed closely, visibility under the visible condition is calculated 10 to be printed 11 as visibility Vs for calibration. Then, the indicator 5 is used with a visibility meter 4 to be calibrated at a specified distance to measure visiblity V. The results are compared with a value of the visibility Vs for calibration to calibrate the visibil ity meter 4. This eliminates the need for a large environment testing chamber for calibration.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a visibility meter calibration device for calibrating a visibility meter that measures visibility on a road, etc., based on the brightness contrast of an index detected from a predetermined distance. It is something.

[Conventional technology]

FIG. 3 is an explanatory diagram showing a conventional visibility meter calibration device. In the figure, 1 is an environmental test chamber for reproducing the test environment of the visibility meter. 2 is a visibility situation reproduction device that creates visibility conditions such as rain, snowfall, etc. in this environmental test chamber 1, and 3 is a visibility situation reproduction device that is installed in the environmental test chamber 1, and has a bright area painted white and a dark area painted black. It is an index having the following. 4 is a visibility meter that is calibrated; 4a constitutes this visibility meter 4;
A brightness/darkness detection device 4b using a television camera or the like that detects the brightness/darkness of the index 3 constitutes a visibility meter 4 together with the brightness/darkness detection device 4a. This is an image processing device that calculates visibility.

Next, the operation will be explained. When calibrating visibility meter 4,
First, a test environment with a visibility condition having a predetermined visibility value is created in the environmental test chamber 1 using rain, snowfall, etc. using the visibility condition reproduction device 2.

Next, under such visibility conditions, the index 3 is photographed by the brightness detection device 4a from a position a predetermined distance away, and the image information is sent to the image processing device 4b. FIG. 4 is an explanatory diagram showing an example of image information of the index 3 photographed by the brightness detection device 4a. Image processing device 4
b is from the image information that was taken, cut out the parts surrounded by squares from the black painted dark area 3a and the white painted bright area 3b of the index 3, and obtain the respective brightness data Bt and Bb. Further, the brightness contrast Cd of the index 3 from a position separated by the distance is determined from the brightness data Bt and Bb using the following equation.

Cd = l Bt -nb l/BbNext, based on the brightness contrast (contrast) Cd at this distance and the brightness contrast Co when the index 3 is viewed from the closest distance, the image processing device 4b calculates the visibility V under the visibility condition. Calculated using the following formula.

v = D x [nn(E)/-gn(Cd/Co)
) Here, in the above equation, E is the discrimination threshold.

The calculated visibility V is output to the outside as a visibility output, and is compared with a predetermined visibility value based on the visibility situation created in the environmental test chamber 1 to calibrate the visibility meter 4.

[Problem to be solved by the invention]

Since the conventional visibility meter calibration device is configured as described above, when calibrating the visibility meter 4, it is necessary to reproduce a predetermined visibility situation in the environmental test chamber 1 using rain, snowfall, etc. The environmental test chamber 1 required a full-fledged, large-scale one, and there were problems such as it was not easy to calibrate the visibility meter 4 in a factory, etc., and the cost was high. .

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a visibility meter calibration device that can easily and inexpensively calibrate a visibility meter in a factory or the like.

[Means to solve the problem]

The visibility meter calibration device according to the present invention includes a calibration index in which a plurality of visibility adjusting means are removably arranged on the front surface of an index main body having a bright area and a dark area, and Under a predetermined visibility condition and from a predetermined distance, the brightness detection means detects the brightness of the bright area and the dark area of the index body, and the processing means calculates the brightness contrast and the index body obtained from the detected brightness information. The calibration visibility is calculated based on the brightness and darkness contrast when viewed from the nearest distance.

[For production]

The calibration index according to the present invention reproduces a predetermined visibility situation by attaching and detaching a plurality of visibility adjusting means arranged on the front side of the index body, and under the reproduced visibility condition, bright areas and dark areas of the index body By detecting the brightness of an area from a predetermined distance and calculating the calibration visibility from the brightness contrast determined from the brightness information and the brightness contrast when viewing the indicator body from the closest distance, a large-scale environmental test room is required to calibrate the visibility meter. To make it possible to calibrate a visibility meter without the need, at low cost, and easily.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 4 is a visibility meter to be calibrated, 4a is its brightness detection device, and 4b is its image processing device.Since these are the same or equivalent parts as the conventional ones with the same reference numerals in FIG. 3, detailed explanation will be provided. is omitted.

Reference numeral 5 denotes a calibration index forming the visibility meter calibration device of this embodiment, and FIG. 2 is a plan view, front view, and side view showing details of its structure. In FIG. 2, reference numeral 6 denotes an index body having a dark area 6a painted black and a bright area 6b painted white. Reference numeral 7 denotes a plurality of visibility adjusting means detachably arranged on the front surface of the index body 6. In this embodiment, a fine mesh is used, which is detachably disposed on the front surface of the index body 6.

Furthermore, 8 is a brightness detection means forming the visibility meter calibration device of this embodiment, which detects the brightness of the dark area 6a or the bright area 6b of the calibration index 50 and the index body 6 from a predetermined distance away. Detect and output as brightness information 1
Paired spot luminance meters are used. 9 is an analog-to-digital converter (hereinafter referred to as A) that converts the luminance information output from the brightness detection means 8 from an analog signal to a digital signal.
/D converter). Numeral 10 is a processing means that forms the visibility meter calibration device of this embodiment together with the calibration index 5 and the spot brightness meter 8, and calculates the brightness contrast from the brightness information converted into a digital signal by the A/D converter 9. The calibration visibility is determined based on the obtained brightness and darkness contrast and the brightness and darkness contrast when the calibration index 50 and the index body 6 are viewed from the nearest position. For example, a burner computer is used. Reference numeral 11 denotes a printer for printing the calibration visibility output from the processing means 10.

Next, the operation will be explained. When calibrating visibility meter 4,
First, the visibility adjustment means 7 arranged in front of the calibration index 5
By attaching and detaching the lenses and adjusting their number, a predetermined visibility situation can be reproduced.

Next, under such visibility conditions, the dark area 6a and the bright area 6b of the indicator body 6 are measured through the visibility adjusting means 7 by each spot luminance meter of the brightness/darkness detection means 8 from a position that has been observed by a predetermined distance. Detects brightness and outputs A/A as brightness information
Send to D converter 9.

The A/D converter 9 converts the received luminance information from an analog signal to a digital signal and inputs it to the processing means 10.

The processing means 10 generates brightness data Bt and B of the dark area 6a and bright area 6b of the index body 6 based on the input luminance information.
b is read, and the brightness contrast Cd of the calibration index 5 from a position separated by the distance is determined using the following equation.

Cd = Bt - Bb /Bb Next, based on the brightness contrast (contrast) Cd at this distance and the brightness contrast co when the calibration index 50 and the index body 6 are viewed from the nearest, the processing means 10 calculates the visibility under the visibility condition. V is calculated using the following formula.

v = Dx (-6n (E)/-6n(Cd/C
o)) Here, in the above equation, E is the discrimination threshold.

The calculated visibility V is output as a calibration visibility Vs and printed by the printer 11.

Next, the visibility V is measured using the calibration index 5 from the position of the above-mentioned distance using the visibility meter 4 to be calibrated. The measurement of this visibility V is similar to the explanation in the "Prior art" section.
The calibration index 5 is photographed to obtain data on the brightness of its dark region 6a and bright region 6b, and calculation is made from the brightness contrast based on the brightness data and the brightness contrast when the index main body 6 is viewed from a close distance.

The visibility meter 4 is calibrated by comparing the visibility V thus measured with the value of the calibration visibility VS.

In the above embodiment, a fine mensch was used as the visibility adjusting means I, but a frosted glass or the like may also be used.

Further, in the above embodiment, the case of a visibility meter calibration device has been described, but if the calibration index and the light/dark detection means are equipped with environmental resistance as an outdoor device, it can also be used as a visibility meter.

〔Effect of the invention〕

As described above, according to the present invention, a predetermined visibility situation is reproduced by adjusting the number of visibility adjusting means arranged in front of the indicator body, and under this visibility situation, from a predetermined distance, the indicator body Detect the brightness of the bright and dark areas of the area, and calculate the calibration visibility from the brightness contrast obtained from the brightness information and the brightness contrast when viewing the indicator body from the closest distance. This eliminates the need for a large environmental test chamber, and has the effect of providing a visibility meter calibration device that can easily calibrate a visibility meter at a low cost in a factory or the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a visibility meter calibration device according to an embodiment of the present invention, FIG. 2 is a plan view, front view, and side view showing details of the calibration index, and FIG. 3 is a conventional visibility meter calibration device. FIG. 4 is an explanatory diagram showing an apparatus, and FIG. 4 is an explanatory diagram showing an example of image information of an index photographed by the brightness measuring apparatus. 5 is a calibration indicator, 6 is an indicator body, 6a is a dark area, 6b is a bright area, 7 is a visibility adjustment means, 8 is a brightness detection means, and 10 is a processing means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A calibration index in which a plurality of visibility adjustment means are removably arranged on the front surface of an index body having a bright area and a dark area, and a calibration index in which a predetermined visibility situation is reproduced by the visibility adjustment means. Brightness detection means for detecting the brightness of bright areas and dark areas of the indicator body from a predetermined distance, and brightness information detected by the brightness contrast and the brightness detection means when the indicator body of the calibration indicator is viewed from the closest position. A visibility meter calibration device comprising processing means for determining a calibration visibility based on the determined brightness and darkness contrast.