JPH08129074A - Apparatus for detecting presence/absence of accumulation of snow on road surface - Google Patents

Abstract

PURPOSE: To reduce manufacturing costs and improve the detecting accuracy, by providing a memory circuit for storing the time when a reference pulse is generated without an accumulation of snow, etc., a circuit for filtering out noises, a bootstrap circuit and the like. CONSTITUTION: Zebra patterns on the road surface are photographed by a video camera 1. Plus components of image signals are taken by a slicer circuit 4, and one pulse of the plus components is generated by a one-shot multivibrator 5. An AND gate of a noise-filtering circuit 7 is opened simultaneously with the time when a reference pulse is generated based on the plus components of image signals stored in a memory circuit, 6 which does not include noises and is obtained when the zebra patterns are photographed without an accumulation of snow. Voltages of image signals generated from the circuit 7 based on the generation time of pulses in one cycle of vertical synchronous pulses are accumulated in a bootstrap circuit 8. The level of voltages accumulated in one cycle is compared and decided, based on which the presence/absence of the accumulated snow is judged by a judging circuit 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road area snow presence / absence detecting device which is expected to be applied to the fields of road surface snow melting and traffic information systems.

[0002]

2. Description of the Related Art Conventionally, as a road area snow presence / absence detecting device of this type, as shown in, for example, Japanese Utility Model Laid-Open No. 4-55557, various recognition marks of a predetermined shape drawn on a road surface for detecting a road surface condition are provided with a polarizing filter. Illuminate with the attached recognition light source,
It is known that the structure is such that a television camera equipped with a polarizing filter having the same characteristics as the polarizing filter is used to determine the condition of the road surface such as dryness, wetness, snowfall, etc., based on the captured image condition of the recognition mark. There is.

[0003]

However, in the above-mentioned conventional structure, the image of the imaged recognition mark is analyzed by using the image analysis device, and the result of this analysis is discriminated to detect the road surface condition. However, the manufacturing cost of the image analysis device becomes very expensive, and the circuit configuration may become complicated, resulting in lack of convenience in handling, and the degree of popularization may be unavoidable. Have inconvenience.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve such inconvenience, and the gist thereof is a video camera for photographing a zebra pattern provided on a road surface and a plus component of the video signal. Slicer circuit, one-shot multi-vibrator that generates the positive component pulse, and the generation time of the reference pulse based on the positive component of the video signal when shooting the zebra pattern without noise and in the condition of no snow Storage circuit, a noise removal circuit that opens an AND gate according to the generation time of the reference pulse, and a voltage that is based on the generation time of the pulse generated in one cycle of the vertical synchronizing pulse of the video signal from the noise removal circuit A bootstrap circuit for determining the presence or absence of snow according to the voltage level accumulated in the one cycle. The road surface snow presence detection device comprising Te there.

At this time, it is desirable to provide a low pass filter for removing high frequency components of the video signal of the video camera.

[0006]

[Function] The zebra pattern provided on the road surface is photographed by the video camera, the plus component of this video signal is taken out by the slicer circuit, the pulse of this plus component is generated by the one-shot multivibrator, and stored in the memory circuit. The AND gate of the noise removal circuit is opened according to the generation time of the reference pulse based on the positive component of the video signal when the zebra pattern is photographed without snow and without snow, and the video signal from this noise removal circuit The voltage based on the generation time of the pulse generated in one cycle of the vertical synchronizing pulse is accumulated in the bootstrap circuit, and the discrimination circuit determines the presence or absence of snow according to the voltage level accumulated in the one cycle.

[0007]

1 to 13 show an embodiment of the present invention.
Is a video camera, which is installed, for example, from the upper side of the road surface R diagonally downward, and in this case, photographs a zebra pattern 2 consisting of a black and white strip displaying a pedestrian crossing, and FIG. The image projected by D. This video signal is an image in which five white belts and four black belts are alternately arranged as a part of the zebra pattern 2 in a diagonal direction in a state where no noise is introduced. Therefore, the waveform shown in FIG. 4 is exhibited. Here, T is one cycle of the vertical synchronizing pulse, that is, the field cycle, and in this case, it is 1/60 second.

Reference numeral 3 is a low-pass filter, which is shown in FIG.
This is because the high frequency component of the video signal shown in (3) is removed to facilitate the next signal processing. The video signal passed through this low pass filter has the waveform shown in FIG.

Reference numeral 4 is a slicer circuit. In this case, a plus component of 0 V or more of the video signal shown in FIG.
As shown in FIG. 7, it is a circuit for taking out as shown in FIG.

Reference numeral 5 denotes a one-shot multivibrator, which in this case includes a Schmitt circuit, and as shown in FIG. 8, is a circuit for generating a pulse from the waveform of the plus component shown in FIG.

Reference numeral 6 denotes a memory circuit, which is a zebra pattern 2
The reference pulse shown in FIG. 8 based on the plus component of the video signal when the zebra pattern 2 is photographed in a state in which there is no noise of a vehicle, a pedestrian, or the like passing above and there is no snow on the zebra pattern 2. Is a circuit for storing the occurrence times t _{1 to} t ₅ .

Reference numeral 7 is a noise removing circuit, which is composed of an AND circuit, and is a circuit which opens the AND gate in accordance with the generation times t _{1 to} t ₅ of the reference pulse.

A bootstrap circuit 8 is a circuit for accumulating a voltage based on the pulse generation times t _{1 to} t ₅ generated in one cycle T of the vertical synchronizing pulse of the video signal from the noise removing circuit 7. In this case, the pulse of t ₀ shown in FIG. 7 in which the component of −5 V or less is extracted is used as the start pulse and the reset pulse. This circuit generates a staircase waveform of the voltage level L shown in FIG. 9 in the case of the video signal of FIG. 4 in the case of no snow, for example, and the video signal of FIG. 10 in the whole-area snow state. Therefore, the bootstrap circuit 8 generates the waveform of the voltage level L ₁ shown in FIG.

[0014] 9 is a discrimination circuit, shown in FIG. 9, as compared with the voltage level L accumulated in the non-snow conditions, such as 50% as a criterion L _S, this stored voltage level 50 If it is more than%, it is judged that there is no snowfall, and if it is less than this, it is judged that there is snowfall, and it outputs a presence signal.

Since this embodiment has the above configuration, when there is no snow on the zebra pattern 2, the bootstrap circuit 8 outputs a staircase waveform of the voltage level L as shown in FIG. When there is snow on the entire upper surface, the waveform of the voltage level L ₁ is output from the bootstrap circuit 8 as shown in FIG. 11, and when there is snow on a part of the zebra pattern 2 as shown in FIG. 13 and the staircase waveform of the voltage level L _n as shown in FIG.
Compares with these voltage levels L _n and the voltage level L, the voltage level L _n is compared with a predetermined proportion or more in voltage level L,
In this case, if there is more than 50%, it is determined that there is no snow, and if it is less than that, it is determined that there is snow, and because in the case of FIG. 13, there is more than 50%, a signal indicating no snow will be output. It is possible to detect the presence or absence of snow, and especially since the circuit configuration is composed of a simple circuit,
Since an image analysis device such as that of the conventional structure is not used, the manufacturing cost can be reduced, and the noise removal circuit 7 can detect the noise that does not include noise of a vehicle, a pedestrian, or the like passing over the zebra pattern 2. Therefore, the detection accuracy can be improved accordingly.

The low-pass filter 3 removes high-frequency components from the video signal from the video camera 1 and then sends the signal to the slicer circuit 4, so that the next signal processing can be facilitated and detected. The accuracy can be improved.

The present invention is not limited to the above-mentioned embodiment. For example, in the above-mentioned embodiment, a pattern showing a pedestrian crossing is used as the zebra pattern 2, but a separately manufactured zebra pattern is laid on the road surface. However, the zebra pattern can be illuminated by an illuminating light source at night, and in particular, the structure of each circuit described above is appropriately modified and designed.

[0018]

As described above, according to the present invention, the zebra pattern provided on the road surface is photographed by the video camera, the plus component of this video signal is taken out by the slicer circuit, and the pulse of this plus component is generated by the one-shot multivibrator. Then, open the AND gate of the noise removal circuit according to the generation time of the reference pulse based on the plus component of the video signal when the zebra pattern is stored in the storage circuit without noise and without snow. , The voltage based on the generation time of the pulse generated in one cycle of the vertical synchronizing pulse of the video signal from the noise removal circuit is stored in the bootstrap circuit, and the presence or absence of snow accumulation is determined by the determination circuit based on the voltage level accumulated in this one cycle. It is possible to determine that the conventional structure is used. It does not use an image analyzer,
The manufacturing cost can be reduced, and moreover, the noise removal circuit can perform detection without noise such as a vehicle or a pedestrian passing on the zebra pattern, thereby improving the detection accuracy.

Further, by providing the low-pass filter, the high-frequency component of the video signal from the video camera is removed and then the video signal is sent to the slicer circuit, so that the next signal processing can be facilitated. The detection accuracy can be improved.

As described above, the intended purpose can be sufficiently achieved.

[Brief description of drawings]

FIG. 1 is a circuit configuration system diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a detection state according to the embodiment of this invention.

FIG. 3 is a video state diagram of the image monitor according to the embodiment of the present invention.

FIG. 4 is a video signal waveform diagram according to an embodiment of the present invention.

FIG. 5 is a waveform diagram of an example of the present invention.

FIG. 6 is a waveform diagram of an example of the present invention.

FIG. 7 is a waveform diagram of an example of the present invention.

FIG. 8 is a waveform diagram of an example of the present invention.

FIG. 9 is a waveform diagram of an example of the present invention.

FIG. 10 is a waveform diagram of an example of the present invention.

FIG. 11 is a waveform diagram of an example of the present invention.

FIG. 12 is a waveform diagram of an example of the present invention.

FIG. 13 is a waveform diagram of an example of the present invention.

[Explanation of symbols]

 1 Video Camera 2 Zebra Pattern 3 Low Pass Filter 4 Slicer Circuit 5 One-shot Multivibrator 6 Memory Circuit 7 Noise Removal Circuit 8 Bootstrap Circuit 9 Discrimination Circuit L Voltage Level T Cycle

Claims (2)

[Claims] 1. A video camera for shooting a zebra pattern provided on a road surface, a slicer circuit for extracting a plus component of the video signal, a one-shot multivibrator for generating a pulse of the plus component, and a noise-free one. Moreover, a storage circuit that stores the generation time of the reference pulse based on the plus component of the video signal when the zebra pattern is photographed in the snowless state, and a noise removal circuit that opens the AND gate in accordance with the generation time of the reference pulse, A bootstrap circuit for accumulating a voltage based on the generation time of a pulse generated in one cycle of the vertical synchronizing pulse of the video signal from the noise removal circuit, and a discrimination for determining the presence or absence of snow on the basis of the voltage level accumulated in the one cycle A road area snow presence / absence detection device comprising a circuit. 2. The road area snow presence / absence detection device according to claim 1, further comprising a low-pass filter for removing high-frequency components of the video signal of the video camera.