Scanning rangefinder

• US 7,403,269 B2
• Filed: 02/04/2005
• Issued: 07/22/2008
• Est. Priority Date: 02/04/2004
• Status: Active Grant

• Current Assignee: Hokuyo Automatic Co., Ltd., Nidec Corporation
• Original Assignee: Hokuyo Automatic Co., Ltd., Nidec Corporation
• Inventors: Tsukuda, Shinichi, Yamashita, Makoto, Kizukuri, Hiroshi, Mori, Toshihiro
• Primary Examiner(s): Alsomiri; Isam
• Application Number:
  US10/906,135
• Publication Number:
  US 20050168720A1
• Time in Patent Office: 1,264 Days
• Field of Search: 356 401- 515, 359872-881
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

Scanning rangefinder of simple, compact construction. The rangefinder is furnished with: an outer cover (1) in which a transparent window (2) is formed; a cylindrical rotary unit (3) inside the outer cover (1); a scanning/receiving window (4) provided in the rotary unit (3); a dual scanning/receiving mirror (5) disposed, angled, along the rotational axis of the cylindrical rotary unit (3); a motor (6) for rotationally driving the rotary unit (3); a disk part (13) arranged in the cylindrical rotary unit (3), anchored in an inside region thereof; a beam projector (14) anchored in a location where it is disposed slightly spaced apart from the rotational axis of the rotary unit (3); and a light receiver (16) anchored to, arranged coincident with the rotational axis of, the disk part (13) in the inside region of the rotary unit (3), and connected to a distance computation circuit (19).

Claims

1. A scanning rangefinder comprising:

a beam projector that emits a scanning beam as electromagnetic radiation onto a scanning target;

a ray receiver that receives the scanning beam reflected from the scanning target;

a distance computation circuit connected to the ray receiver that computes a distance between the rangefinder and the scanning target based upon the scanning beam reflected from the scanning target;

a rotary unit that can be driven rotationally about a rotational axis;

a rotor magnet connected to a lower portion of the rotary unit;

a stator opposing the rotor magnet along the stator'"'"'s circumference and arranged to impart a rotational drive force to the rotary unit;

a stationary shaft that is located along the rotational axis in the interior of the rotary unit;

a rotational position detector that detects a rotational position of the rotary unit; and

a dual-use reflector located in an upper portion of the rotary unit and arranged to reflect the scanning beam emitted from the beam projector to outside of the rotary unit toward the scanning target, to reflect the scanning beam reflected from the scanning target toward the ray receiver, and to rotate with the rotary unit;

wherein

the ray receiver is located on an upper end portion of the stationary shaft.

2. A scanning rangefinder according to claim 1, wherein:

the electromagnetic radiation is light;

the beam projector includes a laser, LED, or an optical emission source;

the ray receiver is a light receiver; and

the dual-use reflector is a dual-use mirror.

3. A scanning rangefinder according to claim 2, further comprising a receiving lens arranged in between the dual-use mirror and the light receiver;

wherein

the beam projector is situated on an inner wall of the rotary unit.

4. A scanning rangefinder according to claim 3, further comprising a scanning mirror arranged in between the dual-use mirror and the beam projector;

wherein the scanning mirror is situated above the receiving lens.

5. A scanning rangefinder according to claim 3, further comprising a scanning mirror arranged in between the dual-use mirror and the beam projector;

wherein

the scanning mirror is situated below the receiving lens.

6. A scanning rangefinder according to claim 3, wherein the receiving lens includes a clearance hole through which the scanning beam is transmitted.

7. A scanning rangefinder according to claim 2, wherein the dual-use mirror has a scanning mirror section and a receiving mirror-lens section.

8. A scanning rangefinder according to claim 1, further comprising a waveguide system that guides the scanning beam emitted from the beam projector into the upper portion of the rotary unit;

wherein

the dual-use reflector is inclined at a predetermined angle with respect to the rotational axis of the rotary unit; and

the scanning beam emitted from the beam projector is guided by the waveguide system into the upper portion of the rotary unit toward the dual-use reflector.

9. A scanning rangefinder according to claim 1, further comprising:

a scanning optical system that guides the scanning beam emitted from the beam projector to the dual-use reflector; and

a receiving optical system that focuses the scanning beam reflected from the scanning target along the rotational axis onto the ray receiver;

wherein

the rotary unit includes;

a rotary-unit encompassing wall portion; and

a rotary-unit ceiling portion;

wherein

at least a portion of the ceiling portion includes the dual-use reflector; and

the scanning optical system and the receiving optical system are included within a space defined by the rotary-unit ceiling portion, the rotary-unit encompassing wall portion, and the upper end portion of the stationary shaft.

10. A scanning rangefinder according to claim 1, further comprising:

a scanning optical system that guides the scanning beam emitted from the beam projector to the dual-use reflector; and

a receiving optical system that focuses the scanning beam reflected from the scanning target onto the ray receiver;

wherein

at least one of the scanning optical system and the receiving optical system are included within a space below the dual-use reflector and above the stationary shaft.

11. A scanning rangefinder according to claim 10, wherein:

the scanning optical system is arranged to guide the scanning beam emitted from the beam projector along the rotational axis; and

the receiving optical system is arranged to focus the scanning beam reflected from the scanning target along the rotational axis.

12. A scanning rangefinder according to claim 1, wherein the rotary unit is unidirectionally and continuously rotated.

13. A scanning rangefinder according to claim 1, wherein the rotary unit is swung back and forth through a predetermined angle of sweep.

14. A scanning rangefinder according to claim 1, wherein the distance computation circuit is configured for AM based processing.

15. A scanning rangefinder according to claim 1, wherein the rotational position detector includes:

a motor drive clock located on a circumference of the rotary unit; and

an optical interrupter switch anchored along a course that the motor drive clock travels.

16. A scanning rangefinder according to claim 1, further comprising:

a fixed outer cover having a transparent window and enclosing the rotary unit; and

a scanning/receiving window located in a portion of a circumferential wall of the rotary unit at the same height as the transparent window, through which the scanning beam is transmitted into and out of the rotary unit.

17. A scanning rangefinder according to claim 16, further comprising:

a scanning optical system that guides the scanning beam emitted from the beam projector to the dual-use reflector; and

a receiving optical system that focuses the scanning beam reflected from the scanning target along the rotational axis onto the ray receiver;

wherein

at least one of the scanning optical system and the receiving optical system are included within a space below the dual-use reflector and above the stationary shaft.

18. A scanning rangefinder according to claim 16, further comprising a zero calibrator located inside the fixed outer cover that gauges a standard length inside the rangefinder while in a reverse-detecting mode.

19. A scanning rangefinder according to claim 16, further comprising a photoabsorber-based noise calibrator inside the fixed outer cover.

20. A scanning rangefinder according to claim 1, wherein information obtained from the ray receiver and information outputted by the rotational position detector are transmitted to the distance computation circuit through the interior of the stationary shaft.

21. A scanning rangefinder according to claim 1, wherein the rotational position detector is a rotary-angle-detecting resolver.