JP2005257352A - Wrong detection prevention structure for sensor, and sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wrong detection prevention structure for a sensor capable of reducing wrong detections even in a case that it is set outdoors, and the sensor. <P>SOLUTION: In a conventional sensor, reflection of radio wave transmitted from a radio transmission part 11 by a waterdrop dropped from a cover 3 might cause a wrong detection. In this structure, water W which is about to drop from above the radio transmission part 11 is guided out of the transmission part 11 by a water guide means so as not to drop to the front surface side of the transmission part 11. According to this, the degree of the reflection of radio wave can be reduced to prevent wrong detections of the sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an erroneous detection preventing structure for a sensor that is installed outdoors that is affected by rainfall, snowfall, and the like and detects the presence of a vehicle or a pedestrian mainly using radio waves, and a sensor using the same.

  Conventionally, as a sensor for detecting a vehicle or a pedestrian on a road using radio waves, for example, a road surface of a road on a road disclosed in Patent Document 1 is scanned with radio waves, and the object on the road surface is scanned by the scan. By detecting the presence / absence and the position of the object, detection means for obtaining at least one of information related to obstacles and traffic flow existing on the road surface, and information detected by the detection means, Notification means for notifying at least one of a driver of a vehicle traveling on a road and a road manager, and the detection means scans and emits pulsed radio waves toward the road surface, and the road surface from the launch. There is a detection means of a road monitoring system that detects the presence and position of an obstacle on the road surface from the time difference reflected and returned.

JP 2002-367073 A

  However, in a sensor such as that described in Patent Document 1, radio waves transmitted by snow on the radome of the sensor or water drops falling from the cover are reflected, and there is no original detection target by receiving the reflected waves. In some cases, the presence of a vehicle or a pedestrian may be erroneously detected due to the reflected wave. When such a false detection occurs, for example, a system for lighting a road around the road in conjunction with the detection of the vehicle or the presence of a pedestrian is detected, and the presence of the pedestrian is notified to the vehicle driver by light emission or the like. When used in a system, the reliability of the system itself may be impaired due to false detection as well as energy loss related to light emission and the like.

  The present invention has been made in view of the problems as described above, and an object of the present invention is to provide a sensor misdetection prevention structure and sensor that can reduce the occurrence of false detection even when installed outdoors.

  In order to achieve the above object, the present invention is configured as follows. That is, the sensor malfunction prevention structure according to the present invention is characterized in that a photocatalyst-containing layer is formed on the outer surface of the radome in the sensor in which the radome is disposed on the front surface of the radio wave transmitting section.

  In addition, the sensor malfunction prevention structure according to the present invention is characterized in that a super-water-repellent coating layer is formed on the outer surface of the radome in the sensor in which the radome is disposed on the front surface of the radio wave transmission unit. .

  Furthermore, the sensor malfunction prevention structure according to the present invention is characterized in that, in a sensor in which a radome is disposed on the front surface of the radio wave transmission unit, a snow-sliding ice coating layer is formed on the outer surface of the radome. is there.

  Furthermore, the sensor malfunction prevention structure according to the present invention is such that, in a sensor in which a radome is arranged in front of a radio wave transmitter, the angle formed between the outer surface of the radome and a horizontal plane is greater than 55 ° on all outer surfaces of the radome. It is characterized by being made.

  Furthermore, in the sensor malfunction prevention structure according to the present invention, a cover is provided at least above the sensor, and water that is about to drip from above the radio wave transmitter of the sensor to the cover other than the radio wave transmitter. It is characterized in that water guiding means for guiding and dropping in the direction is provided.

  Further, the sensor is characterized by detecting a target object using microwaves or millimeter waves.

  A sensor according to the present invention includes the sensor false detection preventing structure according to any one of claims 1 to 6 of the present invention.

  According to the false detection prevention structure for a sensor according to the first aspect of the present invention, by forming a photocatalyst-containing layer on the radome of the sensor, the surface thereof is activated by irradiation with sunlight and is in contact with water. The contact angle is extremely small and hydrophilic, and the attached water does not become water droplets, but forms a uniform and thin water film, reducing the degree of reflection of radio waves due to the water adhering to the radome and causing false detection of the sensor. Can be prevented.

  In addition, according to the sensor false detection preventing structure of the present invention as set forth in claim 2, by providing a super water-repellent coating layer on the radome of the sensor, adhesion of moisture due to rain or condensation is prevented, Since the snow itself does not occur even during snowfall, the degree of reflection of radio waves due to moisture adhering to the radome is reduced, and the occurrence of erroneous detection of the sensor can be prevented.

  According to the sensor false detection preventing structure of the present invention as set forth in claim 3, the snow struck by the snow-sliding icy coating layer formed on the outer surface of the radome is quickly slid down, and the snow is attached to the radome. The degree of radio wave reflection is reduced, and the occurrence of sensor misdetection can be prevented.

  According to the sensor false detection preventing structure of the present invention as set forth in claim 4, the angle formed by the outer surface of the radome and the horizontal plane is larger than 55 ° which is the angle of repose of snow on the entire outer surface of the radome. Thus, the snow attached to the outer surface of the radome slides down quickly due to gravity, the degree of reflection of radio waves due to the snow attached to the radome is reduced, and the occurrence of erroneous detection of the sensor can be prevented.

  Further, according to the sensor false detection prevention structure of the present invention according to claim 5, there is a possibility that the radio wave transmitted from the radio wave transmission unit is reflected by the water droplets dripping from the cover, which may cause a false detection. By guiding the water that is about to drip from above the radio wave transmission unit to the direction other than the radio wave transmission unit by the water guiding means so that it does not fall on the front side of the radio wave transmission unit, the degree of reflection of the radio wave as described above can be increased. This can reduce the occurrence of sensor misdetection.

  According to the invention of claim 6, microwaves and millimeter waves are not easily affected by rainfall or snowfall, and can be detected smoothly even during rainfall or snowfall by preventing snowfall or water droplets outside the radome. The effect obtained by applying the false detection prevention structure according to the present invention to such a sensor using microwaves or millimeter waves is extremely high, which is preferable.

  Further, according to the sensor of the present invention described in claim 7, the sensor is prevented from being erroneously detected due to snowfall or moisture, and in the system in which the sensor and other devices are combined, energy loss or system reliability due to the erroneous detection is achieved. Can be prevented.

BEST MODE FOR CARRYING OUT THE INVENTION The best embodiment according to the present invention will be specifically described below with reference to the drawings.
FIG. 1 is an explanatory diagram showing an embodiment of a sensor to which a sensor false detection preventing structure according to the present invention is applied. The sensor unit 10 is provided in the vicinity of the road R so as to be attached to the upper end of the upright support column 20 and detects a vehicle traveling on the road R and a pedestrian around the road R by the built-in sensor 1. Is. A radome 2 is provided on the front side of the radio wave transmitter 11 of the sensor 1, and the radome 2 is formed using a synthetic resin such as polycarbonate so that it is substantially transparent in terms of radio waves. . Around the sensor 1, a side trapezoidal and front rectangular cover 3 is attached to cover the periphery of the sensor 1 and the radome 2 including the upper part. The sensor unit 10 is configured such that the radio wave radiating unit 11 faces slightly downward in order to direct the radio wave radiated from the sensor 1 toward the road R plane.

  Since the radio wave radiating unit 11 is made slightly downward, when rain falls on the cover upper surface 31 of the cover 3 or when condensed water slides down, water drops from above the radio wave radiating unit 11 of the cover 3. However, the water shielding plate 41 is provided at the tip of the cover upper surface 31 located above the radio wave radiation unit 11, and the water blocked by the water shielding plate 41 is attached to the cover side surface 32 of the cover 3. The water guiding means 4 is formed by the water shielding plate 41 and the water guiding plate 42 so as to be guided by the water guiding plate 42 and fall below the cover side surface 32, so that the water W is placed on the front surface of the radio wave radiation unit 11 by the water guiding means 4. Can be prevented from dripping, and the degree of reflection of radio waves can be reduced.

  FIG. 2 is a cross-sectional view showing details of the radar unit 10 near the radar 1. The sensor 1 is provided with a radio wave transmission unit 11 and a radio wave reception unit 12 on the back side of the radome 2, and the radio wave reception unit 12 receives a reflected wave reflected by a detection target of the radio wave transmitted from the radio wave transmission unit 11. Thus, detection objects such as vehicles and pedestrians are detected. Transmission and reception of radio waves are performed by being controlled by the control unit 13, and the received reflected waves are calculated by the calculation unit 14 to determine the presence and type of the moving body.

  Here, the radome 2 generally has a semicircular shape so that the radio wave transmission unit 11 needs to radiate radio waves over a wide range to some extent, so that the radio waves are radiated uniformly. The angle θ formed between the upper end of the radome 2 and the horizontal plane is smaller than the horizontal plane, but the angle θ formed between the outer surface near the upper end of the radome 2 and the horizontal plane is set to be greater than the angle of repose of snow 55 °. Therefore, it is possible to prevent snow from attaching stably and to reduce the degree of reflection of radio waves due to snow.

  FIG. 3 is an enlarged cross-sectional view of the outer surface of the radome 2. A coating layer 5 is formed on the outer surface of the radome 2 made of synthetic resin, and the surface characteristics provided by the coating layer 5 prevent snow and water droplets from being attached, and the degree of reflection of radio waves caused by them is reduced. Is done.

  When the coating layer 5 is a photocatalyst-containing layer, the photocatalyst contained in the coating layer 5 is activated by being irradiated with sunlight, and the outer surface becomes hydrophilic with a very low contact angle with water. As a result, the water adhering to the outer surface of the radome 2 does not become water droplets but forms a thin water film, so that reflection of radio waves from the surface due to water droplets and reflection of radio waves due to thick water are prevented. The degree of reflection is reduced.

  When the coating layer 5 is a super water-repellent coating layer, the outer surface of the coating layer 5 has a very large contact angle with water, and most of the water adhering to the outer surface of the coating layer 5 adheres to the outer surface of the coating layer 5. Without falling, and snow does not adhere itself, and the degree of reflection of radio waves due to them is reduced.

  Here, the super water-repellent coating layer is, for example, a petal-like transparent alumina film formed on a substrate as described in JP-A-2001-254030 by the present applicant, and the petal-like transparent alumina film is subjected to corona discharge treatment or Plasma treatment is performed to remove adsorbed moisture and impurities adsorbed on the surface and to activate the surface, and then a water-repellent film is formed on the surface, so that the contact angle with water on the outer surface is increased. It shows a coating layer in a state of 140 degrees or more.

  Furthermore, when the coating layer 5 is a snow-sliding ice-type coating layer, even when it snows, the snow ice attached to the outer surface of the coating layer 5 is quickly slid down due to the snow-sliding property provided on the outer surface of the coating layer 5, This prevents the degree of reflection of radio waves generated by snow.

  Here, the snow-sliding ice coating layer is a water repellency having a surface tension of 35 dyne / cm or less on the base material as described in JP-A-2002-180035 by the present applicant, for example, and the sliding angle of water droplets Has a sliding surface of 40 degrees or less, and has an outer surface on which the ice frozen on the outer surface in a temperature range of -2 to -5 degrees slides on the outer surface of the coating layer in a non-breaking manner under a constant load due to a load from the horizontal direction. It shows things.

It is explanatory drawing which shows one Embodiment of the sensor to which the erroneous detection prevention structure of the sensor concerning this invention was applied. It is sectional drawing which shows the detail of the sensor part of the sensor shown in FIG. It is sectional drawing which shows the detail of radome vicinity of the sensor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor 11 Radio wave transmission part 2 Radome 3 Cover 31 Cover upper surface 4 Water conveyance means 5 Covering layer 10 Sensor unit

Claims (7)

A sensor malfunction-preventing structure, wherein a radome is disposed on the front surface of the radio wave transmission section, and a photocatalyst containing layer is formed on the outer surface of the radome. A sensor in which a radome is disposed on the front surface of a radio wave transmission section, wherein a super-water-repellent coating layer is formed on the outer surface of the radome. A sensor in which a radome is arranged on the front surface of a radio wave transmission section, wherein a snow-sliding ice-covering layer is formed on the outer surface of the radome. A sensor in which a radome is arranged in front of a radio wave transmission section, wherein the angle formed by the outer surface of the radome and a horizontal plane is greater than 55 °. A cover is provided at least above the sensor, and water guide means is provided on the cover for guiding and dropping water that is about to drip from above the radio wave transmitter of the sensor in a direction other than the radio wave transmitter. Sensor malfunction prevention structure characterized by The sensor malfunction detection structure according to claim 1, wherein the sensor detects a target object using microwaves or millimeter waves. A sensor comprising the sensor false detection prevention structure according to claim 1.

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