JP2010103731A - Planar antenna and radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change the angle of a planar antenna with respect to a radar device housing without using a tilting mechanism. <P>SOLUTION: Disclosed is the planar antenna which has a planar base plate and an antenna element provided on a substrate, wherein the base plate is fixed to the housing of the radar device. The base plate has a first area where the antenna element is not arranged, and a second area where the antenna element is arranged. When the second area is driven by a driving means provided in the housing while the first area is fixed to the housing, since the second area is bent between the first and second areas so as to be a predetermined angle with respect to the housing, a mounting angle of the planar antenna can be changed with respect to the housing of the radar device even without using the tilting mechanism for tilting the planar antenna, and a beam axis can be adjusted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a planar antenna including an antenna element, and more particularly to a planar antenna having a variable angle with respect to a casing of a radar apparatus.

  The on-vehicle radar device scans the periphery of the vehicle with a radar signal, receives a reflection signal from the target object, and detects the target object. In the case of an on-vehicle radar device, target objects to be detected are other vehicles, roadside installations, and the like, and these are likely to be on the same road surface as the vehicle on which the radar device is mounted. Therefore, in order to reliably obtain the reflected signal, the on-vehicle radar device is attached to the vehicle body so that the beam axis of the radar signal faces a direction parallel to the road surface.

  Here, when a planar antenna having a plurality of antenna elements arranged on a plane and having a beam axis formed in a direction perpendicular to the planar antenna is used, when the radar apparatus is mounted on a vehicle, By adjusting the mounting angle of the housing so that the vertical ground axis is parallel to the planar antenna, the beam axis is adjusted to face in the direction parallel to the road surface. Patent Document 1 describes the adjustment of the beam axis in the on-vehicle radar device.

Conventionally, the adjustment of the beam axis has been specifically performed in the following procedure. Here, for convenience, a beam axis adjustment method on a horizontal road surface is shown. First, the angle of the beam axis with respect to the casing is detected for each radar device, and the inclination of the casing with respect to the ground axis when the beam axis is in the horizontal direction is detected. Then, when the casing of the radar device is attached to the vehicle body during the assembly process of the vehicle body, in the subsequent inspection process of the vehicle body, the operator can visually confirm the inclination of the housing using the level pipe, and the inclination of the housing is Adjust the mounting angle of the chassis manually so that the inclination is correct.
JP 2000-56009 A

  By the way, in-vehicle radar devices are mounted in low-profile areas such as in the front or rear bumper of the vehicle or in the fog lamp unit below the bumper in order to reduce the influence on the design of the vehicle body. Then, when adjusting the beam axis as described above, the operator is forced to take a work posture with a heavy burden. Further, since the beam axis adjustment is performed after the radar apparatus is attached to the vehicle body together with vehicle parts such as a bumper and a fog lamp unit, other vehicle parts interfere with manual work. For these reasons, there has been a problem that work efficiency is deteriorated.

  Therefore, in order to improve the work efficiency of beam axis adjustment, the present inventor has attached an antenna that can be tilted with respect to the housing by a tilting mechanism such as a hinge, and an antenna mounting angle with respect to the housing by tilting the antenna. Invented a radar apparatus having a motor for changing the frequency. This radar device drives the motor in response to an external signal input after the housing is fixed to the vehicle body, and changes the antenna mounting angle, so that the beam axis can be adjusted without requiring difficult manual work. can do.

  However, today, in-vehicle radar devices are strongly demanded to reduce costs. Accordingly, the present inventor has come up with the idea of omitting the antenna tilting mechanism in order to reduce the number of parts and assembly man-hours in the radar apparatus and to realize cost reduction.

  Accordingly, an object of the present invention made in view of such a point is to provide a planar antenna having a variable mounting angle with respect to a radar apparatus housing without using a tilting mechanism, and a radar apparatus having the same.

  In order to achieve the above object, a planar antenna according to the first aspect of the present invention includes an antenna element and a planar base plate on which the antenna element is disposed and fixed to a casing of a radar apparatus. In the planar antenna, the base plate is provided with a second region in which the antenna element is disposed in the housing in a state where the first region in which the antenna element is not disposed is fixed to the housing. When driven by the driving means, the second region is bent between the first and second regions so that the second region is at a predetermined angle with respect to the housing.

  According to the above aspect, when the second region is driven by the driving means provided in the housing while the first region is fixed to the housing, the second region is moved to the housing. Since it is bent between the first and second regions so as to be at a predetermined angle with respect to the body, the mounting angle of the planar antenna to the housing of the radar apparatus can be changed without using a tilting mechanism that tilts the planar antenna. The beam axis can be adjusted. Therefore, the cost of the radar apparatus can be reduced by omitting the tilting mechanism.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

  FIG. 1 is a diagram for explaining a usage state of a radar apparatus according to the present embodiment. A radar device 10 that scans the front of the vehicle 1 is mounted in a front bumper of the vehicle 1, and transmits a millimeter-wave radar signal (electromagnetic wave) from a planar antenna to the front of the vehicle 1 through the exterior plate on the front surface of the bumper. To do. The radar apparatus receives a reflection signal from a target object such as a preceding vehicle, an oncoming vehicle, or a roadside object, and detects these target objects.

  Since these target objects are likely to be located on the same road surface as the vehicle 1, it is desirable that the beam axis of the radar signal be directed in a direction parallel to the road surface in order to obtain a reflected signal with certainty. Here, the beam axis refers to the direction in which the gain of the radar signal is maximized.

  In this embodiment, in a state where the casing of the radar apparatus 10 is fixed to the vehicle body of the vehicle 1 on a horizontal road surface, the planar antenna with respect to the casing is arranged so that the ground axis perpendicular to the horizontal plane is parallel to the planar antenna. By changing the mounting angle, adjustment is made so that the beam axis faces the horizontal direction, that is, the direction parallel to the road surface.

  FIG. 2 is a diagram for explaining the configuration of the radar apparatus 10. 2A is a schematic view (perspective view) of the radar apparatus 10, and FIG. 2B is a cross-sectional view of the radar apparatus 10 taken along a broken line L in FIG.

  As shown in FIG. 2A, the casing 12 of the radar device 10 has a radome 14 a that is provided on the front surface portion thereof and accommodates a planar antenna facing the front of the vehicle 1, and is fixed to the vehicle 1 by the fixing bolt 13. Fixed to the car body. As shown in FIG. 2 (B), the radar apparatus 10 includes a planar antenna 14 that is fixed to the housing 12 and whose mounting angle with respect to the housing 12 can be changed as will be described in detail later. Here, for the sake of convenience, the mounting angle of the antenna 14 refers to the angle with respect to the radome 14a, and FIG. 2B shows a state where the mounting angle is 0 degrees.

  In addition, the radar apparatus 10 reduces the rotational speed of the motor 18a configured by a brushed DC motor as an example, and the motor 18a at a constant ratio, and converts the rotational motion into a linear motion (arrow D1) of the sliding shaft 18c. It has a reduction mechanism 18b for conversion and a sliding shaft 18c. The end of the sliding shaft is pivotally connected to the end of the planar antenna 14 by a pin 20.

  The radar apparatus 10 also has a tilt sensor 26 that detects the inclination of the planar antenna 14 with respect to the ground axis on the back surface of the planar antenna 14, and a transmission / reception circuit 24 and a control unit are provided in the chassis inside the casing 12 behind the planar antenna 14. 16. The transmission / reception circuit 24 has a VCO (voltage controlled oscillator) that generates a millimeter-wavelength transmission signal, and supplies the generated radar signal to the planar antenna 14 via the waveguide 25. The control unit 16 includes a microcomputer and a motor driver, and receives a signal indicating the inclination of the planar antenna detected by the tilt sensor 26, and via various vehicle control devices mounted on the vehicle 1 and an in-vehicle LAN. Configured to communicate. When a signal instructing beam axis adjustment is input from a personal computer or the like connected to the vehicle control device of the vehicle 1, the control unit 16 responds to this by detecting the inclination of the planar antenna 14 and moving the motor 18 a. Driving is performed, and the mounting angle of the planar antenna 14 with respect to the housing 12 is changed so that the inclination of the planar antenna 14 with respect to the ground axis becomes 0 degrees (that is, parallel to the ground axis). Here, the motor 18a, the speed reduction mechanism 18b, and the sliding shaft 18c correspond to “driving means”. In the above description, signal lines between the control unit 16, the tilt sensor 26, and the motor 18a are not shown.

  FIG. 3 is a diagram for explaining a first configuration example of the planar antenna 14. 3A is a front view of the planar antenna 14, FIG. 3B is a cross-sectional view taken along the broken line L1 in FIG. 3A, and FIG. 3C shows a change in the mounting angle of the planar antenna 14. .

  As shown in FIGS. 3 (A) and 3 (B), the planar antenna 14 has a metal base plate 14b molded into a flat shape, and is laminated and pasted on the base plate 14b, and has an antenna element on the surface. And an antenna substrate 14c formed thereon. The base plate 14b is made of a material such as aluminum having a certain degree of rigidity. The antenna substrate 14c has a flexible film formed of a dielectric material such as Teflon (registered trademark) or liquid crystal polymer, for example, and a conductor (for example, copper) foil ground plane is provided on the back surface thereof. On the surface thereof, the transmission line 14d of the microstrip line and the antenna element 14f for transmitting the radar signal transmitted by the transmission line 14d to the space are configured by the conductive foil. The transmission line 14d is connected to the waveguide 25 at the connection terminal 14e, and receives a radar signal from the waveguide 25.

  In the configuration as described above, the base plate 14b includes a region A2 (corresponding to the “first region”) fixed to the housing 12 and a region A1 (“second region”) in which the antenna element 14f is disposed. And the opening 14s is provided between the two regions A1 and A2, thereby relatively reducing the rigidity of the portion. Or you may provide the notch part 14t, as shown in FIG. By doing so, the base plate 14b is configured to be bendable between the regions A1 and A2 when the region A1 is driven by the sliding shaft 18c. The arrangement and number of openings 14s or notches 14t are not limited to the patterns shown in FIGS. 3 and 4, and the base plate 14b can be formed by relatively reducing the rigidity of the portion between the two regions A1 and A2. The configuration that enables bending is included in this embodiment.

  In the planar antenna 14 configured as described above, as shown in FIG. 3C, when the area A1 is driven by the linear motion (arrow D1) of the sliding shaft 18c (arrow D2), the area A1, The base plate 14b is bent between A2. Along with this, the antenna substrate 14c is also bent. Therefore, since the angle of the area A1 with respect to the housing 12 changes, the attachment angle of the planar antenna 14 changes.

  At this time, since the plane is maintained by the rigidity of the base plate 14b in the region A1 in which the antenna element 14f is disposed, the antenna element 14f is disposed on the beam axis even if the base plate 14b is bent between the regions A1 and A2. It is formed in a direction perpendicular to the region A2. Therefore, the direction of the beam axis bm changes as the angle of the region A2 with respect to the housing 12, that is, the attachment angle, as shown in the drawing, so the attachment angle is adjusted so that the region A2 is parallel to the ground axis. As a result, the beam axis can be adjusted in the horizontal direction.

  FIG. 5 is a diagram illustrating a second configuration example of the planar antenna 14. 5A is a front view of the planar antenna 14, FIG. 5B is a cross-sectional view taken along the broken line L <b> 2 in FIG. 5A, and FIG. 5C illustrates the tilting operation of the planar antenna 14.

  In this example, as shown in FIGS. 5A and 5B, the thickness of the portion between the two regions A1 and A2 of the base plate 14b is relatively thin (for example, one or both sides of the part). To provide a groove 14u), the rigidity is relatively lowered. By doing so, when the region A1 is driven by the sliding shaft 18c, it is configured to be bendable between the two regions A1 and A2.

  By doing so, as shown in FIG. 5C, when the region A1 is driven by the linear motion (arrow D1) of the sliding shaft 18c (arrow D2), the base plate 14b is interposed between the regions A1 and A2. Is bent, and accordingly, the antenna substrate 14c is also bent. Therefore, the angle of the region A1 with respect to the housing 12, that is, the mounting angle of the planar antenna 14 changes, and the direction of the beam axis bm changes accordingly. Therefore, the beam axis can be adjusted by adjusting the mounting angle of the planar antenna 14.

  By providing the planar antenna 14 in the radar apparatus 10, the mounting angle of the antenna 14 can be made variable without using a tilting mechanism such as a hinge. Therefore, by omitting the tilting mechanism, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced.

  Further, when the tilt mechanism is used, the transmission / reception circuit 24 needs to be attached to the planar antenna 14 and tilted together with the planar antenna 14. However, by omitting the tilt mechanism, the transmission / reception circuit 24 is separated from the planar antenna 14. Can be provided. This will be described with reference to FIG.

  6A and 6B are diagrams showing the arrangement of the planar antenna 14 and the transmission / reception circuit 24 when the tilt mechanism 22 is used. As shown in FIG. 6A, in order to provide the transmission / reception circuit 24 apart from the planar antenna 14, the millimeter-wave radar signal generated by the transmission / reception circuit 24 is supplied to the transmission line 14d of the planar antenna 14. Although it is necessary to use the waveguide 25, when the planar antenna 14 is tilted by the tilting mechanism 22, the waveguide 25 is bent (arrow P). Then, since the inner diameter of the waveguide 25 changes, the transmitted signal is lost. In order to avoid this, as shown in FIG. 6B, a transmission / reception circuit 24 is attached to the back surface of the planar antenna 14, and a radar signal is supplied to the transmission line 14d of the planar antenna 14. 14 and the transmission / reception circuit 24 need to be tilted.

  In this regard, in the present embodiment, as shown in FIG. 6C, the planar antenna 14 is connected to the waveguide 25 in a region fixed to the housing 12 and has a millimeter wavelength supplied from the waveguide 25. The radar signal is configured to be transmitted to the antenna element 14f through the transmission line 14d. Therefore, since the mounting angle of the planar antenna 14 can be changed without bending the waveguide 25, the transmission / reception circuit 24 can be provided separately. At this time, the transmission line 14d is bent as the antenna substrate 14c is bent. However, since the radar signal is transmitted on the surface of the transmission line 14d, the loss of the radar signal is reduced as compared with the waveguide 25 whose inner diameter changes by bending. It can be suppressed.

  For example, when the transmission loss per mm of the transmission line 14d is about 0.03 dB, the transmission loss when the length from the connection terminal 14e to the waveguide 25 to the first element of the antenna element 14f is about 20 mm. Is about 0.4 dB. In this case, it has been confirmed by the inventors' experiment that the increase in transmission loss due to the bending of the planar antenna 14 is about 0.04 dB when the bending angle is 45 degrees. Then, since the angle at which the planar antenna 14 is bent for beam axis adjustment is predicted to be about ± 5 degrees, the transmission loss of the radar signal that is increased by bending the planar antenna 14 is so small that it does not cause a problem in practice.

  By separating the transmission / reception circuit 24 from the planar antenna 14 in this way, the following effects can be obtained.

  As a first effect, the load on the motor 18a can be reduced by removing the weight of the transmission / reception circuit 24. That is, when the tilting mechanism 22 is used, in addition to the weight of the transmission / reception circuit 24, the pressure applied by the spring for suppressing gear backlash in the tilting mechanism 22 is a load on the motor 18a. When the base plate 14b is bent, the stress of the base plate 14b becomes a load on the motor 18a. Here, since the load due to the pressurization by the spring mechanism and the load due to the stress of the base plate 14b are substantially equal, the load on the motor 18a is reduced as much as the weight of the transmission / reception circuit 24 is reduced. Therefore, a motor with a small torque can be used, and further cost reduction can be achieved.

  As a second effect, the heat radiation efficiency of the transmission / reception circuit 24 can be improved. The circuit element of the transmission / reception circuit 24 generates heat by generating a millimeter wavelength signal. However, when the transmission / reception circuit 24 is attached to the planar antenna 14, heat is conducted to the housing 12 via the tilt mechanism 22, The body 12 was radiating heat. On the other hand, by providing the transmission / reception circuit 24 away from the planar antenna 14 in the casing 12, heat can be directly conducted to the casing 12 and radiated from the casing 12.

  Here, the operation of the radar apparatus 10 configured to include the planar antenna 14 as described above will be described with reference to FIGS.

  FIG. 7 is a control block diagram of the radar apparatus 10. When a signal instructing beam axis adjustment is input from an inspection terminal such as a personal computer connected to the vehicle control device of the vehicle 1, the control unit 16 acquires a signal indicating the tilt of the planar antenna 14 from the tilt sensor 26. Based on this, the motor 18a is driven to change the mounting angle of the antenna 14.

  FIG. 8 is a diagram for explaining changes in the inclination and attachment angle of the planar antenna 14 for each state of the casing 12 of the radar apparatus 10. First, with reference to FIG. 8A, an operation in the case where the housing 12 is attached to be tilted forward will be described. When the tilt sensor 26 detects the inclination θ of the planar antenna 14, the control unit 16 calculates the driving amount of the motor 18a for pushing the lower end portion of the planar antenna 14 forward and changing the mounting angle by θ. The motor 18a is driven by the amount. As a result, the mounting angle of the antenna 14 changes by θ degrees.

  Next, with reference to FIG. 8B, an operation when the casing 12 is attached to be inclined rearward will be described. Similarly, in this case, when the tilt sensor 26 detects the inclination θ of the planar antenna 14, the control unit 16 pulls back the lower end portion of the planar antenna 14 backward to change the mounting angle by θ by the driving amount of the motor 18 a. And the motor 18a is driven by the drive amount.

  By changing the mounting angle of the antenna 14 in this manner, the inclination of the planar antenna 14 with respect to the ground axis is adjusted to 0 degrees even when the housing 12 is tilted and fixed to the vehicle body. It is adjusted so that the axis is oriented horizontally.

  FIG. 9 is a flowchart for explaining the operation procedure of the radar apparatus 10. This is executed when an instruction signal for instructing beam axis adjustment is input in the vehicle inspection process.

  When the instruction signal is input (S2), the control unit 16 acquires the tilt of the planar antenna 14 from the tilt sensor 26 (S4). Then, when the inclination of the planar antenna 14 is within an adjustable angle range (for example, within 0 ° ± 5 °) (YES in S6), it is confirmed whether the inclination of the planar antenna 14 is a predetermined value “0” degree. (S7). Here, for example, ± 0.5 degrees is set as the allowable error range with respect to the predetermined value.

  If the inclination is not a predetermined value (NO in S7), the driving amount of the motor 18a corresponding to the change amount of the predetermined unit is instructed, and if the inclination of the planar antenna 14 is forward, the sliding shaft 18c is pushed out. Thus, the motor 18a is rotated in the forward direction (S10, S12). On the contrary, when the planar antenna 14 is tilted backward, the motor 18a is rotated in the reverse direction so as to pull back the sliding shaft 18c (S10, S14). Then, the inclination of the planar antenna 14 is acquired again in step S4, and it is confirmed that the inclination of the planar antenna 14 has reached a predetermined value (YES in S7), and the process is terminated.

  In step S6, when the inclination of the planar antenna 14 is not within the adjustable angle range (NO in S6), an error is output (S16) and transmitted to the inspection terminal via the in-vehicle LAN.

  The control unit 16 repeatedly executes the above-described procedure to drive the motor 18a until the tilt becomes “0” degrees while detecting the tilt of the planar antenna 14 by the tilt sensor 26.

  As described above, the radar apparatus 10 is fixed to the vehicle body in the assembly process of the vehicle body, and in the inspection process after the vehicle body is assembled, a signal instructing adjustment of the beam axis is input from the outside of the radar apparatus 10. The beam axis can be adjusted without the user being forced to take a heavy working posture or restricting the manual operation. Therefore, work efficiency is improved.

  In the above description, the case where the beam axis is adjusted to be parallel to the horizontal direction has been described. However, the angle of the beam axis may be set to an arbitrary angle such as 0.5 degrees downward with respect to the horizontal direction. it can. In that case, the antenna mounting angle can be adjusted so that the antenna tilt corresponding to the angle of the beam axis can be obtained.

  In the above description, the beam axis adjustment on the horizontal road surface has been described. However, when the slope of the road surface is known, the antenna tilt for obtaining a beam axis having a desired angle with respect to the road surface (that is, the tilt with respect to the ground axis perpendicular to the horizontal plane) is detected in advance and the antenna is applied. It is also possible to adjust the beam axis by adjusting the angle at which the antenna is attached to the housing so as to be inclined.

  Note that the size, shape, thickness, number and arrangement of openings or notches, and variation in thickness of the base plate in the planar antenna are not limited to the above example, and the surface of the area where the antenna element is arranged A configuration in which the accuracy is maintained at a certain level or higher (preferably a flat surface or a substantially flat surface) while being bent between the region and the region fixed to the housing is included in the present embodiment.

  As described above, according to the present embodiment, it is possible to change the mounting angle of the planar antenna with respect to the casing of the radar apparatus without using a tilting mechanism that tilts the planar antenna, and the beam axis can be adjusted. Therefore, the cost of the radar apparatus can be reduced by omitting the tilting mechanism.

It is a figure explaining the use condition of the radar apparatus in this embodiment. 1 is a diagram illustrating a configuration of a radar apparatus 10. FIG. 3 is a diagram for explaining a first configuration example of a planar antenna 14. FIG. It is a figure explaining the modification of the 1st structural example of the planar antenna. 3 is a diagram illustrating a second configuration example of the planar antenna 14. FIG. It is a figure which shows arrangement | positioning of the planar antenna 14 and the transmission / reception circuit 24. FIG. 3 is a control block diagram of the radar apparatus 10. FIG. It is a figure explaining the inclination of the planar antenna 14, and the change of an attachment angle. FIG. 3 is a flowchart for explaining an operation procedure of the radar apparatus 10.

Explanation of symbols

10: Radar device, 14: Planar antenna, 14b: Base plate, 14f: Antenna element

Claims (6)

A planar antenna having an antenna element and a planar base plate on which the antenna element is disposed and fixed to a housing of a radar device;
The base plate is driven by a driving means provided in the casing in a second area in which the antenna element is disposed in a state where the first area in which the antenna element is not disposed is fixed to the casing. Sometimes, the planar antenna is bent between the first and second regions so that the second region is at a predetermined angle with respect to the housing. In claim 1,
The planar antenna, wherein the base plate has a thickness between the first and second regions that is smaller than a thickness at the first and second regions. In claim 1,
The planar antenna, wherein the base plate has an opening or a notch between the first and second regions. In claim 1,
The planar antenna, wherein the base plate is connected to a waveguide for supplying a transmission signal having a predetermined frequency to the antenna element in the first region.   A planar antenna according to any one of claims 1 to 3, a casing to which the planar antenna is fixed, and driving means for driving the second region of the planar antenna, and bending the planar antenna. Thus, the radar device adjusts the angle of the second region with respect to the casing to the predetermined angle. In claim 5,
A circuit for generating a transmission signal of a predetermined frequency;
A waveguide connected to the first region of the base plate and supplying the transmission signal to the antenna element;
The radar apparatus according to claim 1, wherein the circuit is provided apart from the planar antenna.

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