Automotive radar detecting lane mark and frontal obstacle

• US 6,317,202 B1
• Filed: 11/12/1999
• Issued: 11/13/2001
• Est. Priority Date: 11/12/1998
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Hosokawa, Toshio, Terui, Takekazu
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/438,398
• Time in Patent Office: 732 Days
• Field of Search: 356/4.01, 356/141.1, 356/5-1-, 180/169, 180/167
• US Class Current: 356/141.1
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

A radar apparatus for automotive vehicles is provided which is designed to emit laser beams to scan a forward zone for detecting moving object such as preceding vehicles and a downward zone for detecting lane marks printed on a road surface for defining a traffic lane. The downward zone is wider than the forward zone horizontally. Each zone has a minimum width required for assuring desired accuracy of radar detection of an object, thereby minimizing the number of emissions of the laser beams, resulting in an increase in lifetime of a laser diode and production of unwanted data on roadside objects having a low probability that the vehicle will collide them. The apparatus also includes a light focusing mechanism which focuses the laser beam on a given area in the downward zone to increase the power density of a return of the laser beam.

Claims

1. A radar apparatus for a vehicle comprising:

a beam source mounted in the vehicle, emitting a beam of light;

a first scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a first scanning area extending horizontally over a first angular range;

a second scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a second scanning area extending on a road surface horizontally over a second angular range which is greater than the first angular range; and

a light receiving mechanism receiving a return of the beam of light directed by said first scanning mechanism to detect an object present in the first scanning area and a return of the beam of light directed by said second scanning mechanism to detect a lane mark printed on the road surface to define a traffic lane.

2. A radar apparatus as set forth in claim 1, further comprising a rotary mirror rotated to change a direction of the beam of light from said beam source so as to scan the first and second scanning areas selectively, said rotary mirror having a plurality of mirror surfaces which are arranged around a periphery of the rotary mirror and which are inclined at different angles to an axis of rotation of the rotary mirror, and wherein said second scanning mechanism includes at least one of the mirror surfaces, while said first scanning mechanism includes the other mirror surfaces.

3. A radar apparatus as set forth in claim 1, wherein said light receiving mechanism includes a light sensitive surface and an upper mirror, the light sensitive surface being responsive to input of the return of the beam of light to produce a signal indicative thereof, the upper mirror being designed to direct light traveling from a lower side of a traveling direction of the vehicle to the light sensitive surface.

4. A radar apparatus as set forth in claim 1, wherein said light receiving mechanism includes a light sensitive surface and a side mirror, the light sensitive surface being responsive to input of the return of the beam of light to produce a signal indicative thereof, the side mirror being designed to direct light falling thereon from a lateral direction traversing a traveling direction of the vehicle to the light sensitive surface.

5. A radar apparatus as set forth in claim 4, wherein the side mirror is so arranged that a mirror surface faces downward.

6. A radar apparatus for a vehicle comprising:

a beam source mounted in the vehicle, emitting a beam of light;

a first scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a first scanning area extending horizontally over a first angular range;

a second scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a second scanning area extending on a road surface horizontally over a second angular range;

a light receiving mechanism receiving a return of the beam of light directed by said first scanning mechanism to detect an object present in the first scanning area and a return of the beam of light directed by said second scanning mechanism to detect a lane mark printed on the road surface to define a traffic lane; and

a light focusing mechanism provided in said second scanning mechanism, said light focusing mechanism focusing the beam of light on a given portion in the second scanning area.

7. A radar apparatus for a vehicle comprising:

a beam source mounted in the vehicle, emitting a beam of light;

a first scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a first scanning area extending horizontally over a first angular range;

a second scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a second scanning, area extending on a road surface horizontally over a second angular range;

a light receiving mechanism receiving a return of the beam of light directed by said first scanning mechanism to detect an object present in the first scanning area and a return of the beam of light directed by said second scanning mechanism to detect a lane mark printed on the road surface to define a traffic lane; and

a light focusing mechanism provided in said second scanning mechanism, said light focusing mechanism focusing the beam of light on a given portion in the second scanning area;

wherein said light focusing mechanism includes a concave mirror which directs the beam emitted from said beam source so as to scan the second scanning area.

8. A radar apparatus as set forth in claim 7, wherein the second angular range is greater than the first angular range.

9. A radar apparatus for a vehicle comprising:

a beam source mounted in the vehicle, emitting a beam of light;

a first scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a first scanning area extending horizontally over a first angular range;

a second scanning mechanism directing the beam from said beam source forward of the vehicle so as to scan a second scanning area extending on a road surface horizontally over a second angular range;

a light receiving mechanism receiving a return of the beam of light directed by said first scanning mechanism to detect an object present in the first scanning area and a return of the beam of light directed by said second scanning mechanism to detect a lane mark printed on the road surface to define a traffic lane;

a light focusing mechanism provided in said second scanning mechanism, said light focusing mechanism focusing the beam of light on a given portion in the second scanning area; and

a rotary mirror rotated to change a direction of the beam of light from said beam source so as to scan the first and second scanning areas selectively, said rotary mirror having a plurality of mirror surfaces which are arranged around a periphery of the rotary mirror and which are inclined at different angles to an axis of rotation of the rotary mirror,

wherein said second scanning mechanism includes at least one of the mirror surfaces and said first scanning mechanism includes the other mirror surfaces.

10. A radar apparatus as set forth in claim 9, wherein said light receiving mechanism includes a light sensitive surface and an upper mirror, the light sensitive surface being responsive to input of the return of the beam of light to produce a signal indicative thereof, the upper mirror being designed to direct light traveling from a lower side of a traveling direction of the vehicle to the light sensitive surface.

11. A radar apparatus as set forth in claim 9, wherein said light receiving mechanism includes a light sensitive surface and a side mirror, the light sensitive surface being responsive to input of the return of the beam of light to produce a signal indicative thereof, the side mirror being designed to direct light falling thereon from a lateral direction traversing a traveling direction of the vehicle to the light sensitive surface.

12. A radar apparatus as set forth in claim 11, wherein the side mirror is so arranged that a mirror surface faces downward.