JPH1172554A - Vehicle-mounted milimeter wave radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and surely detect, for example, an obstacle within a specific height range by applying beams being stopped down by a fixed antenna and performing horizontal scanning by rotating a reflection plate. SOLUTION: The reflection plate 12 is mounted rotatably at a certain angle by a rotary shaft 11 that is provided at its central part and rotates by a drive mechanism between a position being indicated as the reflection plate 12 and a position being indicated as a reflection plate 12'. When the reflection plate 12 is located at the position of the reflection plate 12 due to the rotation, incidence beams B1 from an antenna 10 are emitted in the direction of radiation beams BO. When the reflection plate 12 is located at the position of the reflection plate 12', beams are emitted in the direction of radiation beams BO' and a reflection plate horizontal section is on a straight line, so that the beam width does not change in horizontal direction. A rotary angle at the position of the reflection plate 12' is set to ψ+γ. However, the angle γ of beams can be selected within a range where the radiation beam BO' cannot be applied to the antenna 10. By stopping down the beam width of incidence beams from the antenna 10, a search accuracy in the horizontal direction can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an in-vehicle millimeter-wave radar device, and more particularly to an in-vehicle millimeter-wave radar device suitable for detecting an obstacle or the like.

[0002]

2. Description of the Related Art A radar device using a millimeter wave band for detecting an obstacle or the like mounted on a vehicle has been developed. The purpose of this millimeter wave radar device is to monitor the front of the vehicle in the traveling direction. In this case, it is necessary to perform beam scanning within a range of, for example, ± 30 °. This is the same in the case of detecting a following vehicle in the direction opposite to the traveling direction. In addition, if a vehicle running in parallel on a road having a plurality of lanes on one side is also monitored, monitoring in almost all directions is required.

As a technique for performing beam scanning in a radar apparatus, a rotary joint used particularly in the microwave band is well known (for example, "Radar Technology", IEICE, 1990, 7, 7th printing, p. 169). reference). FIG. 2 is a structural explanatory view of a rotary joint. A portion A connected to a transceiver and a portion E connected to an antenna are a rectangular waveguide (or a coaxial cable), and upper and lower portions B and D of a choke joint C are circular. In the waveguide, mode conversion is performed at the connection between the rectangular waveguide A and the circular waveguide B and at the connection between the circular waveguide D and the rectangular waveguide E, respectively. The choke joint C is a portion where two circular waveguides overlap, and the length of the overlap is 1 /
By using four wavelengths, the portion where the circular tube wall at the tip of the circular waveguide B is cut off is electromagnetically short-circuited even if it is spatially connected to the outside, and the two circular waveguides B,
By providing a gap g (generally 1/10 wavelength or less) between D, the antenna side has a structure capable of non-contact rotation.
In this way, the beam scanning is performed by rotating the waveguide D and the portion connected to the antenna above the waveguide D together with the antenna by a driving system (not shown).

[0004] As another power supply method for performing beam scanning without using a rotary joint, there is a beam power supply method (Kenichi Miya, "Satellite Communication Technology", IEICE Showa)
56.7, 3rd edition, PP.142-143). In this method, a feeder system is configured by using a plurality of beam feeding reflectors, and the beam feeding reflector and the antenna are rotated.

All of the above techniques involve rotation of the antenna, but there is also a technique in which the antenna is fixed and scanning is performed by rotating only the reflector. FIG. 3 is a schematic diagram of a radiometer system mounted on a helicopter and measuring a radiation wave of 98 GHz from the ground surface (WJWILSON et.al, "Mi
llimeter- Wave Imaging Sensor ", IEEE Tran.Microwave
Theory and Techniques, Vol. MTT-34, NO. 10, Oct. 1986). In FIG. 3, radiators from the ground are reflected by a reflector 33 rotatably supported on a helicopter,
The light is reflected again by the offset parabolic antenna 32 fixed to the helicopter, and is received by the millimeter wave radiometer 31 having the receiving feeder at the focal position. In this configuration, by rotating the reflector 33 about an axis 34 (dotted line in FIG. 3) parallel to the flight direction of the helicopter, scanning in a range of ± 22.5 ° in a direction perpendicular to the flight direction on the ground is performed. Is going. This reciprocating cycle is 30 ms (about 33 Hz). In addition, an axis perpendicular to the flight direction at the center of the reflector (point 37 in FIG. 3)
, The scanning is performed in a range of 0.4 ° in the width in the flight direction on the ground by rotating the reflection plate 33 around an axis perpendicular to the plane of the drawing.

Another example of a system using the rotation of a reflector is a microwave radiometer antenna mounted on the Earth Observing Satellite Nimbus 7 ("Antenna Handbook",
See Ohm PP.331-332). This means that 6.6, 10.69, 18.0, 21.0 and 37.
A beam of five frequencies of 0 GHz (each using orthogonal polarization) is radiated by a common primary radiator, and the beam is directed in a direction of 42 ° below the satellite main body by an inclined reflector. The beam scanning is performed by rotating the reflecting mirror around the vertical axis of the satellite body within a range of ± 25 °. Other beam scanning methods in the millimeter-wave band, for beam scanning widths of several degrees, include a method of moving the primary radiator or the secondary reflector of the Cassegrain antenna, and a wedge with a tapered thickness. A method of rotating a dielectric in front of a dielectric lens is known (NCCurie et.al, "P
rinciples and Applications of Millimeter Wave Rada
r ", PP.551-554, Artech House, 1987).

Further, as a technique similar to the rotation of the reflection plate,
There is a scanning mechanism of a copying machine or a facsimile machine using a laser light source. FIG. 4 shows a schematic configuration thereof. In the outer surface of a columnar cylinder 41 having a regular polygonal cross section, mirror surfaces 42, 42... Is rotated at a constant speed about the center axis 43 of the cylinder. The laser light from the laser light source 44 is made to be incident on any one of the mirror surfaces in a spot shape. As the cylinder 41 rotates, the incident angle of light with respect to the mirror surface changes, and the traveling direction of the reflected light from the mirror surface is determined by the arrow 41A shown in the figure.
When it rotates in the direction, it changes in the forward direction. Thus, a horizontal scan on the light receiving surface 45 for receiving the laser light reflected by the mirror surface is performed. This scanning is one horizontal scanning with one mirror surface. Further, by gradually changing the inclination of the central axis 43, the vertical scanning on the light receiving surface 45 is performed.

[0008]

The structure of a vehicle-mounted radar device must be small and lightweight, and its surveying distance is as short as several hundred meters at most for an automobile. Under these conditions, a millimeter wave having a wavelength of 1 cm or less is generally used. In the case of such a short wavelength, a waveguide system such as a waveguide or a coaxial waveguide also has a size of about the wavelength. For this reason, it is not easy to realize a structure such as a rotary joint or a structure such as a beam feeding system with sufficient accuracy.

On the other hand, the method of scanning by simply rotating a reflector used in a helicopter or the Nimbus No. 7 satellite is a method more suitable for a millimeter-wave radar device to be mounted on a vehicle. It was not developed for the purpose of preventing collision of a moving object on the ground such as a car. For this reason, the scanning range (distance, angle), scanning speed, transmission / reception power, processing method after receiving a reflected wave, and the like are different. Also, as a radar device for an automobile, it is not necessary to scan two-dimensionally in the vertical and horizontal directions using a point beam, but only in the horizontal direction, and the vertical direction is, for example, a height of 2 mm from the ground.
In most cases, it is sufficient to be able to detect the presence of obstacles and other vehicles up to the m-th position. Such a point has not been taken into account in the conventional technique of performing scanning by rotating the reflector.

An object of the present invention is to provide a millimeter-wave radar device for a vehicle, whose scanning mechanism is simple, has excellent durability, is lightweight and can be constructed at low cost, and is suitable for detecting obstacles on the road. .

[0011]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a beam emitting / receiving means for emitting a millimeter wave beam fixed to a vehicle and receiving an incident millimeter wave beam. Reflecting the millimeter-wave beam emitted from the means in the scanning direction and reflecting the millimeter-wave beam returned from the scanning direction to the beam emitting / receiving means, and A vehicle-mounted millimeter-wave radar device, comprising: a reflector that is rotatably mounted; and a reflector driving unit that rotationally drives the reflector.

Further, the present invention is characterized in that the reflecting surface of the reflecting plate is formed such that a millimeter wave beam formed in the scanning direction is wide in a vertical direction and narrow in a horizontal direction. A millimeter-wave radar device for use in a vehicle is disclosed.

Further, according to the present invention, a plurality of the beam emitting / receiving means are provided, and the reflector driving means continuously rotates the reflector in the same direction. An apparatus is disclosed.

Further, according to the present invention, a plurality of the reflectors are provided, and the plurality of reflectors are mounted on the same rotating shaft, and the reflector driving means continuously rotates the rotating shaft in the same direction. A vehicle-mounted millimeter-wave radar device characterized by the above features is disclosed.

Further, according to the present invention, the reflector is composed of a plurality of reflectors whose reflection surfaces are not all the same in curvature, and is mounted on the same rotating shaft. A vehicle-mounted millimeter-wave radar device characterized by continuously rotating in the same direction is disclosed.

Further, the present invention discloses an on-vehicle millimeter-wave radar device characterized in that means comprising the above-described scanning mechanism and antenna system are provided separately for a transmission system and a reception system.

[0017]

Embodiments of the present invention will be described below. FIG. 1 shows an example of a scanning mechanism of an in-vehicle millimeter-wave radar device according to the present invention, and FIG.
FIG. 1B is a cross-sectional view of the center of the antenna 10 and the reflector 12 taken along a horizontal plane.
Is a cross-sectional view when a horizontal center portion is cut by a vertical plane, and R is a traveling direction of the vehicle. As the antenna 10,
Although the drawing shows a cross section of the parabolic antenna, this may be an antenna of another shape, for example, a horn reflector antenna. The reflecting plate 12 is made of a metal plate such as iron or aluminum, or a lightweight material such as plastic, and if necessary, is reinforced to prevent mechanical deformation. On the surface where the beam BI is incident and reflected, a layer of a substance having high conductivity is formed so that a sufficient radio wave reflectance can be obtained.
The thickness is determined by, for example, gold plating, spattering, or bonding of a gold foil, taking into account the skin effect on the wavelength of the radio wave to be used. As for the shape of the reflecting plate 12, here, its horizontal section is a straight line as shown in FIG. 1 (a), and its vertical section is usually a straight line. As shown in ()), those having a curved reflecting surface can be used. In this embodiment and the following embodiments, all the reflectors will be described as being curved as shown in FIG. 1B.

In FIG. 1A, a reflecting plate 12 is rotatably mounted within a certain angle range by a rotating shaft 11 (perpendicular to the plane of the drawing) provided at the center thereof.
And the position shown as the reflector 12 'is rotated by a drive mechanism not shown. Due to this rotation, when the antenna 1 is at the position of the reflection plate 12,
The incident beam BI from 0 is emitted in the direction of the radiation beam BO, and in the direction of the radiation beam BO 'when located at the position of the reflector 12'. Since the horizontal cross section of the reflector is straight, the beam width is horizontal. Does not change in direction. However, FIG.
In (a), beams BI, BO, etc. show only the central axis of the beam. The geometric relationship in the horizontal direction is simple. To make the incident angle from the antenna 10 with respect to the vehicle body traveling direction R 90 ° -θ and set the beam scanning range to ± γ around the vehicle body traveling direction R, FIG. The rotation angle ψ of the reflector 12 shown in FIG.

It is easily obtained that ψ = π / 4− (θ + γ) / 2 and the rotation angle at the position of the reflection plate 12 ′ should be ψ + γ. However, the angle γ of the radiation beam can be selected as long as the radiation beam BO ′ does not cover the antenna 10. Then, by narrowing the beam width (half width) of the incident beam from the antenna 10 as much as possible, it is possible to improve the accuracy of the horizontal search within this scanning range. In FIG. 1A, it is assumed that the rotating shaft 11 directly supports the reflector at the central portion in the vertical direction of the reflector, and this corresponds to the central portion of the reflector 12 in the vertical section as viewed in FIG. Corresponds to the fact that the rotating shaft 11 is attached in the vertical direction passing through the position indicated by the point C. However, it is also possible to use the rotation axis 11 as a vertical axis passing through the point C ′ in FIG. 1B and connect this axis and the reflection plate 12 with another support to rotate. In this case, the relationship of (Equation 1) needs to be corrected, but when the distance between the points C and C ′ in FIG. 1B is small, no large difference occurs.

On the other hand, when the reflector has a structure in which the vertical cross section is curved, as shown in FIG.
Of the incident beam has a beam width β (> α) when viewed in the vertical direction.
As a radiation beam. However, in FIG. 1B, each beam is shown by a boundary line of its half width. It goes without saying that the beam width β of the radiation beam is determined by the curvature of the reflector. Assuming that a beam emitted with a vertical beam width β (degrees) travels a distance L (m) from the beam focal point F and becomes a beam having a half-value width of height h (m),

H (m) = L (m) · (π / 180) · β (degrees) Here, L is a distance from the focal point F. However, since the distance between the focal point F and the reflector is usually small, L may be considered as a distance from the reflection plate. FIG. 5 shows a numerical example of (Equation 1). A scan of L = 100 m or more can be covered to a height of about 1.7 m with a radiation beam of β = 1 °. The plate does not have to be curved, but L = 10 m
In the case of such a close position, the height (half width) of the radiation beam of β = 1 ° is about 17 cm, and the height in the vertical direction is in the range of about 2 m, for example, for a vehicle having a high vehicle height. When an antenna is mounted on the upper part, if the purpose is to detect a short-distance, low-height vehicle, vertical scanning is also required. However, as shown in FIG. 1 (b), the beam width is vertically changed by a vertically curved reflector.
For example, if the beam is expanded so that β = 10 °, a beam having a height of 1.7 m is obtained even when L = 10 m, and sufficient scanning can be performed without scanning in the vertical direction.

Next, a description will be given of a drive mechanism for rotating the reflector, which is omitted in FIG. FIG. 6 shows an example of a drive system for rotating and scanning the reflector in a predetermined angle range by reciprocating motion. The reciprocating drive mechanism 61 supports the arm 62 by the supporting portion 63 so as to be movable only in the reciprocating direction. Perform a reciprocating motion. One end of the arm 62 is connected to a rotary joint 65 having one end fixed to the reflector 12, and the other end of the arm 64 is connected to a rotary joint 66. The reciprocating motion causes the reflection plate 12 to reciprocate around the rotation axis 11. In addition, as another example of the drive system, the reflection plate 12 may be continuously rotated in one direction around the rotation shaft 11 in FIG. This can be achieved by rotating the rotating shaft 11 directly by a motor (not shown) or via a transmission mechanism.

Next, the mechanical characteristics of the above-described rotary drive mechanism will be considered. Assuming that the vehicle is an automobile, on a general road, for example, when the vehicle speed is 50 km / hr, the speed per second is about 14 m.
/ Sec, when the vehicle speed becomes 100 km / hr, the speed per second is about 2
8 m / sec. For example, in order to perform at least one scan while the vehicle travels 1 m, a reciprocating motion as shown in FIG.
The movement of the reflector 12 in (a) to the position of the reflector 12 'is at least 1/14 sec at a vehicle speed of 50 km / hr.
If the reflection plate 12 of FIG. 1A reciprocates and one reciprocation is one cycle, at a vehicle speed of 50 km / hr, at least one cycle is reciprocated at 1/7 sec, that is, 7 cycles / sec. There is a need. Vehicle speed 100km /
When it reaches hr, it becomes 14 cycles / sec. To realize such a high-speed reciprocating motion, a large force is required at the time of reversing the rotation direction. In order to cope with this, since the reduction in the area of the reflector is limited by the wavelength itself, the reflector itself is made as light as possible and a means such as providing a cover made of plastic or the like to avoid wind pressure is used. Is desirable. The installation of the cover is also desirable for removing rain, snow and the like. As the reciprocating drive mechanism 61, a motor and a crank mechanism may be used, but a reciprocating motion can be realized by using an electromagnet like a voice coil of a speaker. When the rotating shaft 11 of the reflection plate is continuously rotated in one direction, at least one scan is performed during 1 m of traveling, and at a speed of 50 km / hr, 14 revolutions / sec.
c = 840 rpm, 100 km / h when traveling 2
8 rotations / sec = 1680 rpm, which requires a considerably high speed rotation. This mechanism does not require a large force at the time of reversing the rotation direction as in the case of reciprocating motion, and the driving system is simple. However, in the signal processing system, the radiation beam is
It is necessary to control so as to emit the beam through the gate and receive the reflected radio wave only when the angle is within the 2γ angle range of (a). The time for scanning this 2γ once is the time for one rotation of the reflector. 2γ / 2π.

It should be noted that no matter which drive system is used,
In the signal processing system, it is necessary to always know in which direction the radiation beam is directed, but this can be easily realized by a conventional technique such as mounting a rotary encoder on the rotating shaft 11.

FIG. 7 shows another configuration example of the scanning mechanism of the millimeter-wave radar device mounted on a vehicle according to the present invention. In this configuration example and the configuration examples described below, the structure of the reflection plate itself and its driving mechanism are not particularly described except when necessary, but they are the same as those in FIG. In the case of the configuration example shown in FIG. 1, the incident beam is incident along the horizontal plane, so that the antenna is incident from a direction of 90 ° -θ with respect to the traveling direction so that the antenna does not hinder scanning in the traveling direction R. I have. For this reason, the horizontal scanning range is restricted on the condition that it does not cover the antenna. However, the effective reflection area of the reflector with respect to the incident beam decreases as the normal direction of the reflector is away from the incident beam direction.
The angle θ in (a) cannot be made too small, so that the horizontal scanning range is considerably limited. The configuration example of FIG. 7 is one method for solving this problem, and FIG.
As shown in the figure, the antenna 10 is placed in front of the vehicle traveling direction R,
Further, as shown in FIG. 2B, the incident beam BI is incident on the reflection plate 12 at an angle δ obliquely upward from below the horizontal direction. The normal direction of the reflector 12 at the point C at which the incident beam BI (the central axis thereof) is incident on the reflector 12 is the horizontal direction in FIG. 1B, but here the normal direction CN is higher than the horizontal direction. Angle δ / 2 slightly downward
And the radiation beam BO is substantially horizontal. The beam width of the radiation beam BO is
However, the antenna 10 is prevented from entering the beam width. The rotation axis 11 is
Assuming a vertical axis passing through the point C in (b), the radiation beam BO
(The center axis of) rotates in substantially the same plan view (horizontal plane). In FIG. 7, it is assumed that the beam is incident obliquely upward from below to the reflector. However, it is needless to say that the same applies when the beam is incident obliquely downward from above. .

According to the configuration of FIG. 7, the horizontal scanning range can be made wider than that of FIG. 1. However, when the angle δ of the deviation of the incident beam from the horizontal in FIG. There are restrictions on beam expansion. Therefore, if the angle δ is increased, the beam can be expanded in the vertical direction almost freely. FIG. 8 is a vertical sectional view showing a configuration example when δ = 90 ° in FIG.
If the tangent line at the center position is at an angle of 45 ° with the horizontal direction, the incident beam BI is incident on the reflector 12 vertically upward and is emitted in the horizontal direction. The reflection plate 12 is rotated by a vertical rotation shaft 11 by a motor 81 fixed to the vehicle. In this configuration, the rotating shaft 1
There is an advantage that the effective reflection area is constant over one full rotation angle of 360 °, and a horizontal scanning of 360 ° can be performed by a combination of one reflector and one antenna. If the rotary shaft 11 is reciprocated in a certain angle range, it goes without saying that horizontal scanning is performed only within the range. It goes without saying that the configuration in FIG. 8 may be all upside down.

Next, a modified example of the configuration example shown in FIG. 1 or FIG. 7 will be described. FIG. 9 shows, based on the configuration example shown in FIG. 7, a range of ± γ toward the traveling direction R of the vehicle and a range of ± γ toward the rear opposite to the traveling direction R by one reflector. 12 and its driving mechanism.
In this configuration, two antennas 10A and 10B are attached so that the vertical cross section is as shown in FIG.
The reflection plate 12 is continuously rotated. Each antenna 10A,
Millimeter wave transmitting / receiving units 91A and 91B are attached to 10B, respectively. The control unit 94 captures the rotation angle of the reflection plate 12 indicated by the rotary encoder 92 captured via the interface 93, and when the beam reflected by the reflection surface of the reflection plate 12 is within ± γ with respect to the traveling direction R. The millimeter wave is output from the transmission / reception unit 91A via the switch 95 and is radiated from the antenna 10A. The reflected signal received by the antenna 10A and detected by the transmission / reception unit 91A is processed by the processing unit 96 via the switch 95.
To be sent to When the beam reflected by the reflection surface of the reflection plate 12 is within ± γ with respect to the direction opposite to the traveling direction R, the transmission / reception unit 91B via the switch 95
The millimeter wave is output from the antenna 10B and radiated from the antenna 10B.
The reflected signal detected at 1B is sent to the processing section 96 via the switch 95. As described above, the horizontal scanning in a wider range can be realized by the configuration method of FIG. A similar configuration is also possible with the configuration method shown in FIG. 1. In this case, however, only the direction in which the radiation beam is directed to any of the plurality of antennas should be avoided, or if the radiation beam is directed to the antenna, its position ( Angle) may be used as a reference to detect the direction of the radiation beam.

FIG. 10 shows four antennas 10A to 10D.
And four reflectors 12A fixed to one rotating shaft 11
FIGS. 7A and 7B are vertical cross-sectional views showing a configuration example in the case of having the antennas 10 to 12D. The antenna 10A and the reflector 12A, the antenna 10B and the reflector 12B, the antenna 10C and the reflector 12C, and the antenna 10D and the reflector 12D have the configuration of FIG. In each case, a beam incident from an oblique direction is emitted in a substantially horizontal direction. If the beam width in the vertical direction is increased by using the reflecting surface as a curved surface, the energy returned by reflection when the beam width is expanded beyond the target will be reduced, so that the beam width is almost the same as the height to be detected. Is desirable. Therefore, it is preferable to narrow the beam width as the distance increases, and to widen the beam width when detecting a near object. However, it is impossible with a single reflector. Therefore, as shown in FIG.
By changing the curvature of each 2D so as to emit radiation beams having different beam widths in the vertical direction, it becomes possible to detect an obstacle or the like with high sensitivity regardless of distance. In addition,
In FIG. 10, if the antennas 10C and 10D are eliminated and only the two antennas 10A and 10B are used, scanning is performed only in the traveling direction. In addition, for example, the antennas 10A and 10C and the reflectors 12A and 12C are removed, and R
The scanning may be performed in the direction and the opposite direction. Further, when the target is only the measurement target whose distance is almost constant, scanning with the antennas 10B and 10D and the reflectors 12B and 12D having the same curvature can provide a half rotation speed as compared with the case of FIG. Can achieve the same scanning speed, and 2
One direction can be scanned in parallel. Also, the configuration of FIG. 10 can be realized similarly when the beam is incident on the reflector in the vertical direction as shown in FIG.
It is shown in FIG.

FIG. 12 shows a combination of the two configurations of FIG.
The reflectors 12A and 12B have different curvatures because they rotate on one rotation shaft 11. In this configuration, only two reflectors are mounted, and thus only scanning with two beam widths can be realized, but there is an advantage that scanning can be performed uniformly in all horizontal directions. That is, in the configurations of FIGS. 10 and 11, for example, the incident beam from the antenna 10B of FIG. 10 is not always incident on the reflector 12B or 12D with a sufficient effective area, so that the scanning direction is limited. Since the horizontal beam width is usually very small, multiple reflectors can be mounted around one axis of rotation, but a correspondingly large number of antennas are required, resulting in a complicated system, and in effect, all horizontal directions. Is difficult to scan evenly.

Various examples of the configuration have been described above. In particular, when a distant object is detected, there is a case where the separation of the transmission and the reception becomes difficult in the transmission / reception antenna system. In this case, the above-described scanning mechanisms may be separately set for the transmission system and the reception system so as to synchronize the rotations of the transmission and reception mechanisms. Also, the beam from the antenna is assumed to be sufficiently narrowed to be almost a point beam, but if the beam from this antenna is not sufficiently narrowed, the beam should be narrowed down and in the vertical direction. The curved surface of the reflector is formed so that the beam spreads. For this purpose, the reflecting surface may be concave instead of convex,
Further, not only a one-dimensional curved surface in the vertical direction but also a two-dimensional curved surface including the horizontal direction may occur. further,
If an antenna that emits a beam that spreads to some extent in the vertical direction and is sufficiently narrowed in the horizontal direction is used, the reflector may be planar. The point is that it is only necessary to form a beam that is narrow in the horizontal direction and spread to some extent in the vertical direction and radiate while scanning, based on a combination of the characteristics of the antenna (or the primary radiator) and the shape of the reflecting surface of the reflector. If no special consideration is required for the beam width in the vertical direction, a combination of a pencil beam antenna and a plane reflector may be used.

[0029]

According to the present invention, since the horizontal scanning is performed by radiating the beam narrowed by the fixed antenna and rotating the reflecting plate, the structure is simple and highly reliable, and is economically mounted on a vehicle. A millimeter wave radar device can be realized. Further, by appropriately bending the reflection surface of the reflection plate, there is an effect that an obstacle or the like within a predetermined height range from the ground surface can be efficiently and reliably detected without performing vertical scanning.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a scanning mechanism of a millimeter wave radar device according to the present invention.

FIG. 2 is an explanatory diagram of a conventional rotary joint.

FIG. 3 is a diagram showing a scanning mechanism of the millimeter wave radiometer for helicopter mounting.

FIG. 4 is an explanatory diagram of a laser scanning mechanism such as a copying machine.

FIG. 5 is a diagram illustrating a relationship between a beam width and a reaching distance.

FIG. 6 is a diagram showing an example of a driving mechanism of the reflection plate of FIG. 1;

FIG. 7 is a diagram showing another configuration example of the scanning mechanism of the millimeter wave radar device according to the present invention.

FIG. 8 is a diagram showing another configuration example of the scanning mechanism of the millimeter wave radar device according to the present invention.

FIG. 9 is a diagram showing another configuration example of the scanning mechanism of the millimeter wave radar device according to the present invention.

FIG. 10 is a diagram showing another configuration example of the scanning mechanism of the millimeter wave radar device according to the present invention.

FIG. 11 is a diagram showing another configuration example of the scanning mechanism of the millimeter wave radar device according to the present invention.

FIG. 12 is a diagram showing another configuration example of the scanning mechanism of the millimeter wave radar device according to the present invention.

[Explanation of symbols]

 10, 10A to 10D Antenna 11 Rotation axis 12, 12A to 12D Reflector

Claims (10)

[Claims] 1. A beam emission / reception means for emitting a millimeter wave beam fixed to a vehicle and receiving an incident millimeter wave beam, and reflecting the millimeter wave beam emitted from the means to scan in a scanning direction. And a millimeter-wave beam returned from the scanning direction is reflected and sent to the beam emitting / receiving means, and a reflector mounted rotatably with respect to the vehicle, and the reflector is driven to rotate. And a reflector driving means for the vehicle. 2. The reflector according to claim 1, wherein a reflecting surface of the reflecting plate is formed such that a millimeter wave beam formed in the scanning direction is wide in a vertical direction and narrow in a horizontal direction. 2. The in-vehicle millimeter-wave radar device according to 1. 3. The on-vehicle vehicle according to claim 1, wherein a plurality of said beam radiating / receiving means are provided, and said reflector driving means continuously drives said reflector to rotate in the same direction. Millimeter wave radar equipment. 4. A method according to claim 1, wherein a plurality of said reflectors are provided, said plurality of reflectors are attached to the same rotating shaft, and said reflector driving means continuously rotates said rotating shaft in the same direction. The in-vehicle millimeter-wave radar device according to claim 1 or 2, wherein: 5. The reflecting plate is constituted by a plurality of reflecting plates whose reflecting surfaces are not all the same in curvature and mounted on the same rotating shaft, and the reflecting plate driving means moves the rotating shaft in the same direction. 3. The in-vehicle millimeter-wave radar device according to claim 2, wherein the vehicle is driven to rotate continuously. 6. A beam emitting means fixed to a vehicle for emitting a millimeter-wave beam, and rotatable with respect to the vehicle for reflecting the millimeter-wave beam emitted from the means and emitting the beam in a scanning direction. A first reflector mounted on the vehicle, a second reflector rotatably mounted on the vehicle for reflecting the millimeter wave beam returned from the scanning direction, and a second reflector fixed to the vehicle. Receiving means for receiving the millimeter-wave beam returned from the second reflector, and reflector driving means for synchronously rotating the first and second reflectors. Features Millimeter-wave radar equipment for vehicles. 7. A reflection surface of the first and second reflection plates is formed such that a millimeter wave beam formed in the scanning direction is wide in a vertical direction and narrow in a horizontal direction. The in-vehicle millimeter-wave radar device according to claim 6, wherein: 8. The apparatus according to claim 1, wherein each of said plurality of beam radiating means and said plurality of receiving means is provided in the same number, and said reflector driving means continuously drives said reflector in the same direction. The vehicle-mounted millimeter-wave radar device according to 6 or 7. 9. A method in which a plurality of said first reflectors are provided and attached to a first rotating shaft, and said second reflectors are provided in the same number as said first reflectors and attached to a second rotating shaft. ,
8. The in-vehicle millimeter-wave radar device according to claim 6, wherein the reflector driving unit drives the first and second rotating shafts to rotate continuously in the same direction in synchronization with each other. 9. 10. The first reflector is composed of a plurality of reflectors whose reflection surfaces are not all the same in curvature, and is attached to a first rotation shaft, and the second reflector is attached to the first reflector. A plurality of reflectors having the same number as the reflectors and the curvature of each of the reflection surfaces being equal to each of the first reflectors are attached to the second rotating shaft, and the reflector driving means is 8. The in-vehicle millimeter-wave radar device according to claim 7, wherein said first and second rotating shafts are continuously and rotationally driven in the same direction in synchronization with each other.