JPH10160837A - Radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar apparatus which can maintain an electric characteristic with reference to a secular change and a change in an operating environment while a rise in production costs is being suppressed. SOLUTION: In a scanning radar apparatus, the irradiation direction of a beam is changed by a mechanical scanning operation or an electric scanning operation. The scanning range of the beam is composed of a detection range required to detect an object and a calibration range required to calibrate the inside of the apparatus. A radio-wave absorber 12 which is used to detect a noise level and to change a bias voltage and a control signal so as to make the noise level minimum and a reflector 13 or a delay reflector which is used to calibrate an amplification gain, a transmission output and a transmission frequency are installed in the calibration range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device used for a collision warning system using a millimeter wave band radio wave or a laser beam.

[0002]

2. Description of the Related Art In-vehicle radar systems using radio waves in the millimeter wave band or laser beams have been developed with the aim of applying them to warning devices for rear-end collision and collision prevention. In this on-vehicle radar system, radio waves and light beams are used to detect not only the distance to a reflective object such as a preceding vehicle (hereinafter referred to as a “target”) but also the direction of the target viewed from the vehicle (hereinafter referred to as an “azimuth”). Of the beam is performed. Such beam scanning is a technique required not only for the purpose of detecting the direction of the target and for expanding the detection range, but also for changing the detection range of the target according to the turning state of the vehicle.

The beam scanning method is roughly classified into a mechanical type and an electronic type. As the mechanical scanning, there is one that rotates a reflector or the like that is arranged to face the entire radar device or the primary radiator. Electronic scanning involves arranging multiple antenna elements and primary radiators and radiating radio wave beams from each other in the order of arrangement, or phased by changing the phase of the radio wave to be supplied and changing the direction of the radiated beam Arrays and the like are known.

[0004] The above-mentioned radar apparatus, particularly an on-vehicle radar apparatus using radio waves, is so large that it is difficult to install it in a vehicle interior, and it is often arranged outside a vehicle such as behind a bumper in front of the vehicle. The outside of the vehicle where this radar device is installed is completely different from the air-conditioned cabin, and it is placed in a bad environment such as the ambient temperature that fluctuates greatly depending on the season and region, and the vibration and shock accompanying the running of the vehicle, Various characteristics such as a decrease in the transmission level of the device, a decrease in the reception sensitivity, and an increase in internal noise are likely to occur.

[0005]

In the above-mentioned conventional radar device, the temperature characteristics of the parts used are improved, and the inside of the housing by adding a heater and a cooling device is maintained so that the characteristics at the time of shipment can be maintained even in a bad environment outside the vehicle. Measures such as constant temperature and earthquake resistance have been planned. However, there is a problem that the manufacturing cost of the apparatus increases only with such measures. Accordingly, it is an object of the present invention to provide a radar device capable of maintaining electrical characteristics while suppressing an increase in manufacturing cost.

[0006]

According to one embodiment of the present invention, there is provided a radar apparatus for detecting an object whose scanning range of a beam whose irradiation direction is changed by mechanical or electronic scanning is necessary for detecting an object. A scanning range for calibration and a scanning range for calibration necessary for calibrating the inside of the apparatus are provided. In the scanning range for calibration, a radio wave absorber, a reflector or a delay reflector is installed.

In another radar apparatus of the present invention, a radio wave absorber, a reflector or a delay reflector that appears intermittently is set in a scanning range of a beam whose irradiation direction is changed by mechanical or electronic scanning. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a preferred embodiment of the present invention, a radio wave absorber, a reflector or a delay reflector intermittently appearing in a scanning range of a beam whose irradiation direction is changed by mechanical or electronic scanning. Is constituted by a rotating plate of a radio wave absorber, a reflector or a delay reflector in which slits for passing each beam changed by electronic scanning are shifted in a radial direction and a circumferential direction.

[0009]

FIG. 1 is a block diagram showing the configuration of a radar apparatus according to a first embodiment of the present invention. Reference numeral 11 denotes a radar transceiver, 12 denotes a radio wave absorber, and 13 denotes a reflector. The radar transceiver 11 emits a millimeter wave band radio wave beam whose irradiation direction is changed by mechanical scanning or electronic scanning of the transmitting / receiving antenna 11a. A detection range necessary for detecting an object is set at the center of the scanning range of the beam, and first and second calibration ranges required for calibration inside the apparatus are set on both sides of the detection range. I have.

A radio wave absorber 12 is arranged in a first calibration range, and a reflector 13 is arranged in a predetermined position in a second calibration range. The reflector 13 is made of a plate made of a material having a large reflectivity such as a metal, and is arranged at a position at a shortest distance from the radar transmitter / receiver 11 that the radar device can detect.

The first calibration range in which the radio wave absorber 12 is installed is first scanned by mechanical scanning or electronic scanning of the transmitting / receiving antenna 11a, then the detection range in the center is scanned, and finally the reflector is scanned. A second calibration area where 13 is located is scanned. Subsequently, each range is scanned in the reverse order, that is, in the order of the second calibration range, the detection range, and the first calibration range. The reciprocating scanning to the left and right as described above is repeated at an appropriate cycle.

When scanning the first calibration range, the radio wave radiated from the transmitting / receiving antenna 11a is transmitted to the radio wave absorber 1
2, the reflected wave is not generated. For this reason,
No reflected wave is received by the radar transceiver 11, and its output is nothing but noise. Generally, the noise includes an external noise component such as an interference wave from the radar device of another vehicle arriving from the outside and an internal noise component such as thermal noise and 1 / f noise generated inside the receiver.

However, in this embodiment, since external noise is shielded by the radio wave absorber 12, only internal noise is detected. The bias voltage of elements such as a frequency mixer (mixer) and an amplifier or a circuit is adjusted so that the detected internal noise is minimized. In the detection range, a reflected wave generated by another vehicle to be detected or the like is received by the receiver of the transmitter / receiver 11 through the antenna 11a for both transmission and reception.

In the second calibration range, since the reflector 13 placed on the second calibration range is made of a reflector having a large reflectance such as a metal plate, a large-level reflected wave generated here passes through the transmitting / receiving antenna 11a for radar transmission / reception. Is received by the receiver of the device 11. The output of the receiver is the maximum level of the signal that can be processed by the radar device, and the gain of the amplifier, the amount of attenuation of the attenuator,
Control of input / output impedance and bias voltage of each unit, control of the frequency of a transmission signal, and the like are performed.

As described above, according to the first embodiment, detection of noise and adjustment of the maximum level of the received reflected wave are performed on both sides of the detection range. A second embodiment, which is a modification of the first embodiment, removes the reflector 13 from the second calibration range in FIG. 1 and does not transmit or receive radio waves in the second calibration range. It is only configured to do.

What is received at this time is noise in which external noise is mixed with the above-mentioned internal noise, and the average level and frequency spectrum of this external noise are referred to the internal noise already detected in the first calibration range. Are detected and stored in memory. The external noise stored in the memory is then subtracted from the reflected wave prior to processing of the reflected wave received from the detection range, thereby removing the external noise mixed in the received signal.

FIG. 2 is a block diagram showing the configuration of a radar apparatus according to a third embodiment of the present invention. Reference numeral 21 denotes a radar transceiver, 22 denotes a radio wave absorber having slits formed therein, and 23 denotes a motor. is there.

The radar transmitter / receiver 21 includes five transmitting / receiving aperture antennas 21a to 21e arranged so that the radiation direction of the radio wave is slightly shifted in the width direction of the radiation beam. A disk-shaped radio wave absorber 22 with a slit is disposed in front of the radar transceiver 21 with its center fixed to the rotating shaft of a motor 23. Referring also to the plan view of FIG. 3, the slit-equipped radio wave absorber 22 has a circular shape in order to allow the beams radiated from each of the antennas 21 a to 21 e for both transmission and reception to pass selectively and with a time difference due to rotation. Five slits 22a to 22e are formed while being displaced in the radial direction and the circumferential direction of the plate.

With the rotation of the radio wave absorber 22 having the slit, the radio wave radiated from the antenna 21a for both transmission and reception is radiated through the slit 22a, and the reflected wave reflected by the detection target such as another vehicle is transmitted to the same slit. The signal is received by the antenna 21a, which is used for both transmission and reception, through the antenna 22a. That is,
In the transmission / reception channel including the transmission / reception shared antenna 21a, an object such as another vehicle is detected. At this time, the remaining 4
The radio wave beams emitted from the antennas 21b to 21e are absorbed by the radio wave reflector, and no reflected beam is generated. Therefore, the remaining four transmission / reception channels including the transmission / reception antennas 21b to 21e enter a noise detection state.

With the rotation of the radio wave absorber 22 with the slit, the slit 22a moves away from the antenna 21a, and instead of the slit, the slit 22b moves forward of the antenna 21b. Along with this, the transmission / reception channel including the antenna 21b enters a state of detecting an object, and the transmission / reception channel including the other four antennas enters a noise detection state. As described above, one of the five shared transmission / reception channels including the five shared transmission / reception antennas 21a to 21e is in the object detection state in the order of arrangement, and the remaining four transmission / reception channels are in the noise detection state. .

Each transmission / reception channel has its frequency spectrum or average to control the bias voltage so as to minimize the detected noise or to subtract the detected noise from the reflected wave detected under the detection state. Or store the level in memory.

Although the third embodiment has been described above taking the case of electronic scanning as an example, this embodiment can also be applied to the case of mechanical scanning.

FIG. 4 is a plan view showing the configuration of a radio wave absorber 22 'with slits constituting a radar apparatus according to a fourth embodiment of the present invention. The fourth embodiment is different from the above-described third embodiment in that a disc-shaped electromagnetic wave absorber 2 having a slit is provided.
A part of 2 ′ is not a radio wave absorber but a reflector 22 made of metal or the like.
f, and the other points are shown in FIG.
Is the same as the configuration of the third embodiment shown in FIG.

Therefore, during the period in which the reflector 22f is located in front of the antennas 21a to 21e of the radar transceiver 21, the corresponding transmission / reception channels including each antenna have the second transmission / reception channel in the first embodiment of FIG. The adjustment of the maximum level of the received reflected wave is performed in the same manner as in the scanning period of the calibration range of. During the period in which the radio wave absorber is located in front of the antennas 21a to 21e, detection and storage of noise, adjustment of bias voltage, and the like are performed as in the first to third embodiments.

FIG. 5 is a block diagram showing the configuration of a fifth embodiment of the present invention, in which 31 is a radar transceiver, 31a is a shared antenna for transmission and reception, 32 is a reflector, 33 is a motor, 34
Is a radio wave absorber. The central portion of the reflection plate 32 is fixed to a rotation axis of a motor 33 extending in a direction perpendicular to the plane of the paper,
Rotate.

As shown in FIG. 5 (A), a radio wave beam radiated from a transmitting / receiving antenna 31a of the radar transceiver 31 is reflected by a reflector 32 made of metal or the like and radiated to the outside. The reflected beam reflected by the target object such as the vehicle is received by the receiver of the radar transceiver 31 following the reverse path to the radiation beam. The mechanical scanning of the radiation beam is performed by changing the angle of the reflector.

When the rotation angle of the reflection plate 32 is out of the scanning range with the rotation of the reflection plate 32, the emission of the radio wave beam is interrupted. As shown in FIG. 5B, when the reflection plate 32 further rotates to be in a state where the reflection plate 32 faces the antenna 31a for both transmission and reception, radiation of the radio wave beam is started again. The radiated radio beam is reflected by the reflector 32 and received by the receiver of the transmitter / receiver 31 via the antenna 31a used for both transmission and reception. In this state, the gain of the amplifier, adjustment of the automatic gain control mechanism, and the like are performed so that the reception level becomes the maximum and always matches a predetermined constant value.

As shown in FIG. 5C, the reflection plate 32 is further rotated, and the radio wave absorber 34 is connected to the transmitting / receiving antenna 31 a
, The emission of the radio wave beam is started again. In this state, detection and storage of noise, adjustment of bias voltage to minimize the noise, and the like are performed.

FIG. 6 is a block diagram showing the configuration of a sixth embodiment of the present invention. Reference numeral 41 denotes a transceiver, 42 denotes a polygon mirror, and 43 denotes a radio wave absorber 43. As shown in FIG. 6, a radio wave beam radiated from the transmitting / receiving antenna 41a of the radar transmitter / receiver 41 is reflected by a reflection surface of a polygon mirror 42 made of metal or the like and radiated to the outside.
The reflected beam reflected by an object such as another vehicle is received by the receiver of the radar transmitter / receiver 41 following the reverse path of the radiation beam. Mechanical scanning of the radiation beam is performed by changing the angle of the reflecting surface with the rotation of the polygon mirror.

When the rotation angle of the polygon mirror 42 is out of the scanning range due to the rotation of the polygon mirror 42, the emission of the radio wave beam from the antenna 41a is interrupted. When the reflection surface is further rotated to be in a state of facing the antenna 41a, the emission of the radio wave beam is started again. The radiated radio wave beam is reflected by the reflection surface, and is received by the receiver of the transmitter / receiver 41 via the antenna 41a for transmission and reception. In this state,
The gain of the amplifier, the adjustment of the automatic gain control mechanism, and the like are performed so that the reception level is maximized and always coincides with a predetermined constant value.

When the polygon mirror 42 is further rotated and the radio wave absorber 44 fixed on one of its reflection surfaces faces the antenna 31a for both transmission and reception, radiation of the radio wave beam is started again. In this state, detection and storage of noise, adjustment of bias voltage to minimize the noise, and the like are performed.

FIG. 7 is a sectional view showing the configuration of a delay reflection plate 52 which is a component of the seventh embodiment of the present invention. The delay reflection plate 52 includes a reflection plate 52a such as a metal having a good reflection surface and a dielectric plate 52b such as ethylene tetrafluoride adhered to the reflection surface side. Dielectric plate 52b
The propagation time of the reflected beam increases as the permittivity of the reflected beam increases compared to air.

As a result, the installation position of the reflector 52a can be made substantially closer to the antenna, and the radar apparatus as a whole can be reduced in size. By using this reflector in place of the reflectors 13 and 22f in the radar apparatus of FIGS. 1 and 4, it is possible to reduce the size of the entire radar apparatus.

FIG. 8 is a block diagram showing the configuration of a radar apparatus according to an eighth embodiment of the present invention. Reference numeral 61 denotes a radar transceiver, 61a denotes a mechanical scanning or electronic scanning type common antenna for transmission and reception, and 62 denotes a transmission / reception antenna. The calibration signal oscillator 62a is a calibration signal transmitting antenna. According to this embodiment, a transmitting antenna 62a for transmitting a calibration signal of a constant level and a constant frequency generated by the oscillator 62 is provided outside the detection range of the antenna 61a.

When the detection operation for the detection range by the beam scanning is completed, a predetermined level from the transmission antenna 61a is set.
A calibration signal having a constant frequency is transmitted and received by the antenna 61a that is used for both transmission and reception. The calibration signal is used for detecting a change in the gain or frequency band of the receiver in the radar transceiver 61, and for automatically adjusting the gain or the bias voltage.

FIG. 9 is a block diagram showing the configuration of a radar apparatus according to a ninth embodiment of the present invention. Reference numeral 71 denotes a radar transceiver, 71a denotes a mechanical scanning type or electronic scanning type transmitting / receiving antenna, and 72a denotes a transmitting / receiving antenna. The search signal transmission antenna 72b is a search signal branch line. According to this embodiment, a transmission antenna 72a for transmitting a search signal supplied through the branch line 72b is provided outside the detection range of the antenna 61a.

When the detection operation for the detection range by the beam scanning is completed, a search signal is transmitted from the transmission antenna 72a and received by the antenna 71a for both transmission and reception. This search signal is used for inspection of transmission / reception return characteristics in the radar transceiver 71, detection of fluctuations in the gain and frequency band of the transceiver, automatic adjustment of gain and bias voltage, and the like.

Although the radar apparatus for transmitting and receiving a radio wave beam has been described above, the present invention can be applied to a radar apparatus for transmitting and receiving a light beam such as a laser beam or a sound wave such as an ultrasonic wave.

Further, although the configuration using a flat reflector as the reflector or the delay reflector has been exemplified, a reflector having a concave or convex curved surface may be used. Further, the material of the reflector is not limited to metal, but may be resin or the like.

Further, if a predetermined characteristic cannot be obtained even if the bias voltage or the control signal is changed in the calibration operation, a failure is diagnosed, and the driver is notified by a display or the like to notify the driver of the failure. Appropriate functions such as a function of stopping the operation are added as needed.

[0041]

As described above in detail, the radar apparatus according to the present invention performs the calibration operation between the detection operations, so that the fluctuation of the electric characteristics due to the external environment such as the temperature and the change of the diameter of the element with the aging. Is compensated by changing the bias voltage or the like. For this reason, as in the case of conventional equipment, the use of expensive parts with small temperature changes, expensive temperature compensation circuits, etc., and the use of air conditioners to maintain the temperature to minimize temperature fluctuations are minimized. Unlike the above method, an inexpensive element or circuit having a strict standard can be used, and constant temperature or the like is not required, so that the manufacturing cost of the entire radar apparatus is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a radar apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a radar device according to a third embodiment of the present invention.

FIG. 3 is a plan view of a radio wave absorber with a slit of the radar apparatus according to the third embodiment.

FIG. 4 is a plan view of a radio wave absorber with a slit of a radar apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of a radar apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a radar apparatus according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view showing a configuration of a delay reflector used in a radar device according to a seventh embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a radar apparatus according to an eighth embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of a radar apparatus according to a ninth embodiment of the present invention.

[Explanation of Signs] 11,21,31,41,61,71 Radar transceiver 12,22,34,44 Radio wave absorber 13,22f, 32 Reflector 44 Polygon mirror 52 Delay reflector 62 Calibration signal oscillator 62a, 72a Calibration signal transmission antenna 6

Claims (13)

[Claims] 1. A scanning radar device in which the irradiation direction of a beam is changed by mechanical scanning or electronic scanning. A radar range, wherein a radio wave absorber, a reflector, or a delayed reflector is installed in the calibration range. 2. The apparatus according to claim 1, wherein as a calibration inside the apparatus when a radio wave absorber is installed in the calibration range, a noise level is detected, and a bias voltage or a control signal for minimizing the noise level is changed. A calibration of the operating characteristics of the radar device. 3. The apparatus according to claim 1, wherein a calibration of an amplification gain, a transmission output, a transmission frequency, and other operating characteristics is performed as calibration inside the apparatus when a reflector is installed in the calibration range. Radar equipment. 4. An electronic scanning type radar apparatus in which a beam irradiation direction is changed by mechanical scanning or electronic scanning, wherein an intermittently appearing radio wave absorber, reflector or delay reflector is located in the beam scanning range. A radar device to be installed. 5. The radio wave absorber according to claim 3, wherein the intermittently appearing radio wave absorber, reflector or delay reflector is formed by shifting a slit for passing the scanning beam in a radial direction and a circumferential direction. A radar device comprising a rotating plate of an absorber, a reflector or a delay reflector. 6. The calibration according to claim 4 or 5, wherein when the rotating plate is made of a radio wave absorber, a noise level is detected and a bias voltage or a control signal is changed to minimize the noise level. A radar device wherein calibration of other operating characteristics is performed. 7. The apparatus according to claim 4, wherein the calibration of the amplification gain, the transmission output, the transmission frequency, and other operating characteristics is performed as calibration inside the apparatus when the rotating plate is formed of a reflector or a delay reflector. A radar device characterized by the following. 8. A radar apparatus which scans a beam radiated from a common antenna for transmission and reception by one-way or reciprocating rotation of a reflection plate, wherein a radio wave absorber is fixed to a back surface of the reflection plate. A radar apparatus wherein beam transmission / reception is performed in a state facing a common antenna, and internal noise is detected. 9. A radar apparatus for scanning a beam radiated from a common antenna for transmission and reception by one-way or reciprocating rotation of a reflection plate, wherein transmission and reception of beams are performed in a state where the reflection plate faces the common antenna for transmission and reception. A radar apparatus wherein calibration of amplification gain, transmission output, transmission frequency and other operating characteristics is performed. 10. A radar apparatus for scanning a beam radiated from a common antenna for transmission and reception by rotating a polygon mirror, wherein a radio wave absorber is fixed to at least one surface of the polygon mirror, and the radio wave absorption is used for the common transmission and reception. A radar apparatus wherein transmission and reception of a beam are performed in a state facing an antenna, and internal noise is detected. 11. A radar device for scanning a beam radiated from a transmitting / receiving antenna by rotating a polygon mirror, wherein the beam transmission / reception is performed with at least one surface of the polygon mirror facing the transmitting / receiving antenna. A radar apparatus wherein calibration of amplification gain, transmission output, transmission frequency and other operating characteristics is performed. 12. A scanning radar apparatus in which a beam irradiation direction is changed by mechanical scanning or electronic scanning, wherein the beam scanning range includes a detection range necessary for detecting an object and a calibration range necessary for calibration inside the device. A radar apparatus comprising: a calibration area; and means for transmitting a radio wave for calibration to the radar apparatus in the calibration area. 13. The radar apparatus according to claim 12, wherein the radio wave for calibration is transmitted through a line branched from the radar apparatus.