Radar apparatus
In a radar apparatus, a laser light generating device generates a laser light. An optical device reflects the laser light to output it in a predetermined direction. The optical device has at least two reflective surfaces with different reflectance to the laser light. A reflected light detecting device detects a reflected light when the laser light is reflected by an object. An object detecting device detects the object based on the reflected light. An intensity changing device changes an intensity of the outputted laser light by switching the reflective surfaces. Thus, it can be prevented that an intensity of the reflected light becomes too large and an accuracy of detection of the object can be improved.
1. A radar apparatus, comprising:
a laser light generating means for generating a laser light;
an optical means for reflecting the laser light generated by the laser light generating means to output the laser light in a predetermined direction, the optical means having at least two reflective surfaces with different reflectance to the laser light;
a reflected light detecting means for detecting a reflected light when the laser light outputted from the optical means is reflected by an object;
an object detecting means for detecting the object based on the reflected light detected by the reflected light detecting means; and
an intensity changing means for changing an intensity of the laser light outputted from the optical means by switching the reflective surfaces.
2. The radar apparatus according to claim 1 , wherein:
the optical means includes a rotatable object which rotates around a rotation axis;
the reflective surfaces are formed on a side wall of the rotatable object; and
the rotatable object rotates so that the reflective surfaces reflect the laser light generated by the laser light generating means to output the laser light in a predetermined range of angle in a rotation direction of the rotatable object.
3. The radar apparatus according to claim 2 , wherein:
the reflective surfaces have different tilt angles with reference to the rotation axis of the rotatable object to change a direction of the laser light.
4. The radar apparatus according to claim 1 , wherein:
the laser light generating means, the optical means, the reflected light detecting means, the object detecting means and the intensity changing means are mounted in a vehicle; and
the intensity changing means changes the intensity of the laser light outputted from the optical means based on a speed of the vehicle.
5. The radar apparatus according to claim 4 , wherein the intensity changing means increases the intensity of the laser light outputted from the optical means as the speed of the vehicle becomes higher.
6. The radar apparatus according to claim 1 , wherein:
the object detecting means detects at least a distance to the object based on a time period between a time when the laser light is outputted from the optical means and a time when the reflected light is detected by the reflected light detecting means; and
the intensity changing means changes the intensity of the laser light outputted from the optical means based on the distance to the object.
7. The radar apparatus according to claim 6 , wherein the intensity changing means increases the intensity of the laser light outputted from the optical means as the distance to the object becomes larger.
8. The radar apparatus according to claim 1 , wherein:
the reflected light detecting means outputs a reception signal according to an intensity of the reflected light; and
the intensity changing means changes the intensity of the laser light outputted from the optical means based on a time period when the reception signal is larger than a predetermined value.
9. The radar apparatus according to claim 8 , wherein the intensity changing means decreases the intensity of the laser light outputted from the optical means when the time period becomes longer than a predetermined time period.