JPH0295242A - Fog detector - Google Patents

Abstract

PURPOSE:To accurately detect a fog with a simple constitution and to facilitate adjustment and holding maintenance by providing a detecting circuit, an adding circuit, and a comparator. CONSTITUTION:A signal (a) of white outputted by a white part detecting circuit 7a is amplified 8a to obtain a signal Wa and a signal (b) of black outputted by a black part detecting circuit 7b is inverted and amplified 8b to obtain a signal Bb; and both signals are added 9. Further, the sum signal from a circuit 9 is supplied to and compared by a comparator 10 with a reference value determined by a Zener diode Dz and when the variation of the signal (c) is larger than a reference value, the circuit 10 outputs a contrast signal (d). Then, when a fog is produced in a space between a detected part and the detection part and the visibility decreases, the output difference between the signal (a) of white and the signal (b) of black becomes small and the signal (d) is not outputted by the circuit 10. Consequently, the production of the fog is detected. Further, when there is no fog between the detected part and detection part, on the other hand, the output difference between the signals (a) and (b) increases and the signal (d) is outputted as an output signal (e) from the circuit 10 through a delay circuit 11 to detect the good visibility.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fog detection device, and in particular, detects the contrast ratio of a recognition pattern of a detected part by a detection part, and detects the difference between the detection part and the detected part. This relates to a fog detection device that determines the visibility situation in the space between.

[Background of the invention]

In recent years, road networks such as expressways have been spread across the country due to the large volume of information and transportation and the high speed of movement.

However, in areas where the weather changes rapidly, visibility is greatly reduced due to the occurrence of fog, etc., making it difficult to drive a car. Recently, there has been a strong desire for a detection device that can accurately detect road information such as fog and can greatly contribute to traffic safety.

[Prior art and its problems]

A fog detection device using a photoelectric conversion element in a fog detection section has already been proposed, for example, as shown in Japanese Utility Model Application Publication No. 51-104386.

FIG. 4 is a configuration diagram showing the configuration of the fog detection device.

This fog detection device consists of a light projecting part P and a light receiving part, and a part of the beam projected in a predetermined direction from the light projecting part P is diffusely reflected by fog particles, and the diffused reflection situation is reflected by the light receiving part. detected. Therefore, depending on the amount of fog particles in the space, the strength of the arriving light detected by the light receiving unit changes, and as a result, the amount of fog particles in the atmosphere can be determined from the amount of received light, and based on this, the visibility is The situation (visibility value) was detected.

However, in the above-mentioned frost detection device, the optical axis
1. Optical axis X2 of the light receiving part, beam spread angle α of the emitter P
3. The emitter P and light receiver must be set under predetermined conditions, such as the beam spread angle α2 at the receiver, the beam intensity at the emitter P, and the sensitivity of the receiver. Initial adjustment and maintenance management were extremely difficult.

[Object of the present invention]

The present invention was devised to solve the above-mentioned problems, and its purpose is to simplify the overall configuration, detect fog with high accuracy, and thereby facilitate the installation of the device and facilitate adjustment and maintenance management. An object of the present invention is to provide a frost detection device that is unnecessary.

[Specific Means for Solving the Problems] According to the present invention, a lens system comprising at least one imaging lens and a plurality of photoelectric conversion elements arranged at or near the focal point of the imaging lens It has a detection part and a detected part made of a recognition pattern having different color parts provided at a distance from the detection part, and each color part of the recognition pattern is transmitted to the photoelectric conversion element by the imaging lens. A frost detection device is provided that detects the presence or absence of fog by forming an image on the fog and detecting the difference in shading of each color portion using the photoelectric conversion element.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a schematic diagram showing the structure of the frost detection device of the present invention. The frost detection device of the present invention is comprised of a detected part 1 and a detection part 2. The detected section 1 is installed in front of the detection section 2 in the light receiving direction. The distance between the detected part 1 and the detection part 2 is determined by the focus of the imaging lens, which will be described later. For example, when this device is used in combination with a road warning sign,
They are installed at intervals of about 6 to 7 meters.

The detected part 1 consists of a recognition pattern 6 for the detection part 2 to detect the light transmission state of the space, and the recognition pattern 6 is a rectangular shape of two colors consisting of a white part 6a and a black part 6b. It consists of colored parts.

White and black are suitable colors for the colored part because they can be detected by a general photoelectric conversion element that does not depend on wavelength, but if a color filter is attached to the photoelectric conversion element described later, red, blue, and green can be detected. It is also possible to use a recognition pattern 6 having two or three colors, or more colors. Further, the shape of the colored portion may be arbitrarily selected such as a circle, a triangle, or a quadrangle.

The detection unit 2 includes a main body 3, an imaging lens 4, and two photoelectric conversion elements 5a and 5b.

The main body 3 is made of a corrosion-resistant material such as stainless steel or plastic, and a light-transmitting window 31 is provided in the light-receiving part.
An imaging lens 4 is fixed to the transparent window 31. Also,
Two photoelectric conversion elements 5a and 5b are built into the main body 3 near the focal point of the imaging lens 4.

The imaging lens 4 forms images of the white portion 6a and the black portion 6b of the recognition pattern 6 onto the photoelectric conversion elements 5a and 5b, respectively, and is made of a light-transmitting material such as glass or transparent plastic. In this embodiment, an example is shown in which one imaging lens 4 is used, but in order to more clearly image the white part 6a and the black part 6b, two imaging lenses are used for each photoelectric conversion element 5a. , 5b, respectively. In this case, the photoelectric conversion elements 5a, 5b can be installed.
b is placed at the focal point of the corresponding imaging lens.

The photoelectric conversion elements 5a and 5b detect the intensity of reflected light from the white part 6a and the black part 6b of the recognition pattern 6 imaged by the imaging lens 4, respectively, and generate a predetermined voltage. A photoelectric conversion element such as a planar type or the like is used.

Next, the principle of operation will be explained using a signal processing circuit.

As shown in FIG. 2, the signal processing circuit includes a white part detection circuit 7.
a, a black portion detection circuit 7b, an amplification circuit 8a, an inverting amplification circuit 8b, an addition circuit 9, and a comparison circuit 10.

The white portion detection circuit 7a is configured with the first photoelectric conversion element 5a as a main component, and detects the intensity of reflected light from the white portion 6a.

The black portion detection circuit 7b is configured with the second photoelectric conversion element 5b as a main component, and detects the intensity of reflected light from the black portion 6b.

The amplifier circuit 8a includes an operational amplifier 81, a CdS element 82, etc., and amplifies the signal a from the white portion detection circuit 7a. On the other hand, the inverting amplifier circuit 8b includes an operational amplifier 83, Cd
It consists of an S element 84 and the like, and amplifies the signal from the black area detection circuit 7b. The CdS elements 82 and 84 are photoelectric elements, and when the surrounding illuminance decreases, the resistance increases accordingly, improving the amplification factors of the signals a and signal A, and increasing the output sensitivity.

The comparison circuit IO includes an addition circuit 9 including an operational amplifier 91, a comparator 101, a resistor R1, a Zener diode Dz, and the like.

Note that 11 is a delay circuit, and the delay circuit 11 is connected to the detected part 1.
Comparison circuit 1 detects a sudden change in the space between
The device is designed to output a constant output signal e without malfunctioning even if an abnormal signal is instantaneously output from zero.

In this way, the white signal a output from the white part detection circuit 7a is input to the amplifier circuit 8a, and the amplified signal W is amplified.
A and an inverted amplified signal Bb outputted from the black portion detection circuit 7b, which is input to the inverted amplification circuit 8b and inverted and amplified, are added by the adder circuit 9. Furthermore, the addition signal C from the addition circuit 9 is given to the comparison circuit 1O and compared with a reference value determined by the Zener diode Dz. A contrast signal d is output.

According to the signal processing circuit described above, the detected part l and the detection part 2
If fog or the like occurs in the space between the two and the visibility is reduced, it becomes impossible to clearly detect the white part 6a and the black part 6b, so the output difference between the white signal a and the black signal a becomes smaller. , the contrast signal d is not output from the comparison circuit IO. As a result, the occurrence of fog is detected.

On the other hand, if there is no fog at all in the space between the detected part l (!: detection part 2), the white part 6a and the black part 6
b can be clearly detected, the output difference between the white signal a and the black signal S becomes large, and the contrast signal d from the comparator circuit 10 is outputted via the delay circuit 11 to the output signal e.
is output as

As a result, it is detected that the visibility of the space between the detected part 1 and the detection part 2 is good.

In the present invention, as the recognition pattern 6, a marker 8t, which is generally installed on the shoulder of a road, as shown in FIG.
i20 can also be used. In particular, when the sign 20 equipped with the illumination light 19 is used, the fog detection device can detect the fog all day long, regardless of day or night, with simple installation.

The fog detection device of the present invention is installed on roads and bridges where fog is likely to occur, and when it detects the occurrence of fog, it turns on guide lights, sign lights, warning lights, etc. It can be used to alert people.

〔Effect of the invention〕

As described above, since the fog detection device of the present invention detects fog based on the contrast ratio of the recognition pattern, it can accurately detect fog even if the ambient illuminance changes within the detection range of the photoelectric conversion element, and can Since it has a simple configuration that does not require a light section, it is easy to install the device, and it is also possible to easily perform post-installation adjustments and maintenance management.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of the fog detection device of the present invention. FIG. 2 is an electrical circuit diagram of the fog detection device of the present invention. FIG. 3 is a schematic diagram showing an applied embodiment of the fog detection device of the present invention. FIG. 4 is a configuration diagram of a light projecting section and a light receiving section of a conventional fog detection device. 1 ・ ・ 2 ・ 4 ・ 5a. 6 ・ ・ ・ Detected part ・ Detection part ・ Imaging lens ・ Photoelectric conversion element recognition pattern

Claims (1)

[Claims] A detection section consisting of at least one imaging lens, a plurality of photoelectric conversion elements arranged at or near the focal point of the imaging lens, and a different color section provided at a distance from the detection section. and a detected part consisting of a recognition pattern, each color part of the recognition pattern is imaged on the photoelectric conversion element by the imaging lens, and the photoelectric conversion element detects the difference in shading of each color part. A fog detection device characterized by detecting the presence or absence of fog.