Scanning Rangefinder

• US 20050168720A1
• Filed: 02/04/2005
• Published: 08/04/2005
• Est. Priority Date: 02/04/2004
• Status: Active Grant

• Current Assignee: Hokuyo Automatic Co., Ltd., Nidec Corporation
• Original Assignee: Hokuyo Automatic Co., Ltd., Kizukuri Sekkei, Nidec Corporation
• Inventors: Tsukuda, Shinichi, Kizukuri, Hiroshi, Mori, Toshihiro, Yamashita, Makoto
• Granted Patent: US 7,403,269 B2
• Time in Patent Office: Days
• US Class Current: 356/4.10
• 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:

an optical-beam emitting projector having an optical emission source, said projector for emitting a scanning optical beam directed by the rangefinder onto a scanning target at a radial distance from the rangefinder;

a rotary unit driven rotationally about a rotational axis;

a stationary shaft piece positioned along the rotational axis;

a light receiver disposed on an upper end portion of said stationary shaft piece, for receiving, as a received optical signal, light reflected from the scanning target;

a dual-use mirror disposed in an upper part of said rotary unit so that the scanning beam output from said beam projector is incident on said dual-use mirror and so as to rotate unitarily with said rotary unit, said dual-use mirror therein functioning both as a scanning mirror for reflecting the scanning beam from said beam projector radially outward of said rotary unit to direct the beam onto the scanning target, and as a receiving mirror for reflecting, and guiding so as to introduce into said light receiver, light being the reflection of the scanning beam from the scanning target;

a rotor magnet affixed to a lower portion of said rotary unit;

a stator disposed in a position opposing said rotor magnet along its circumference, for imparting rotational drive force to said rotary unit;

a rotational position detector for detecting rotational position of said rotary unit; and

a distance computation circuit connected to said light receiver and to said rotational position detector, for computing distance to the scanning target based on the optical signal received by said light receiver.

2. A scanning rangefinder as set forth in claim 1, further comprising:

a scanning optical system for guiding to said dual-use mirror the scanning beam emitted from said beam projector; and

a receiving optical system for concentrating superficially onto said light receiver, received light reflected by said dual-use mirror;

at least one of said scanning optical system and said receiving optical system being accommodated within a space formed below said dual-use mirror and above said stationary shaft piece.

3. A scanning rangefinder as set forth in claim 1, further comprising:

a scanning optical system for guiding to said dual-use mirror the scanning beam emitted from said beam projector; and

a receiving optical system for concentrating superficially onto said light receiver, along the rotational axis, received light reflected by said dual-use mirror;

wherein

the rotary unit includes a rotary-unit encompassing wall part and a rotary-unit ceiling part, and at least a portion of said ceiling part is formed by said dual-use mirror; and

both said scanning optical system and said receiving optical system are accommodated within a space formed by said rotary-unit ceiling part, said rotary-unit encompassing wall part, and said upper end portion of said stationary shaft piece.

4. A scanning rangefinder as set forth in claim 2, wherein information obtained from said light receiver and information output by said rotational position detector is transmitted to said distance computation circuit through the interior of said stationary shaft piece.

5. A scanning rangefinder as set forth in claim 4, wherein:

said scanning optical system in making the beam-projector emitted beam incident on said dual-use mirror guides the beam the along the rotational axis; and

said receiving optical system in concentrating onto said light receiver light reflected by said dual-use mirror guides the light along the rotational axis.

6. A scanning rangefinder as set forth in claim 5, wherein said rotary unit is unidirectionally, continuously rotated.

7. A scanning rangefinder as set forth in claim 5, wherein said rotary unit is swung back and forth through a predetermined angle of sweep.

8. A scanning rangefinder as set forth in claim 5, wherein said distance computation circuit is configured for AM-based processing.

9. A scanning rangefinder as set forth in claim 5, wherein said rotational position detector is a rotary-angle-detecting resolver.

10. A scanning rangefinder as set forth in claim 5, wherein said rotational position detector includes a motor drive clock fixed circumferentially on said rotary unit, and an optical interrupter switch anchored in the course along which said motor drive clock travels.

11. A scanning rangefinder as set forth in claim 1, wherein said optical emission source for said optical-beam emitting projector is one selected from a laser and an LED.

12. A scanning rangefinder comprising:

an electromagnetic-radiation projector for emitting a scanning electromagnetic-radiation beam directed by the rangefinder onto a scanning target at a radial distance from the rangefinder;

a rotary unit driven rotationally about a rotational axis;

a stationary shaft piece positioned along the rotational axis;

an electromagnetic wave receiver disposed on an upper end portion of said stationary shaft piece, for receiving as a received electromagnetic-wave signal electromagnetic waves reflected from the scanning target;

a dual scanning/receiving reflector anchored to said rotary unit along the rotational axis of said rotary unit, inclined at a predetermined angle;

an electromagnetic-radiation waveguiding system for guiding into the upper portion of said rotary unit the scanning beam output from said electromagnetic-radiation projector so that the beam is incident on said dual scanning/receiving reflector, for reflecting the scanning beam radially outward of said rotary unit to direct the beam onto the scanning target, and for reflecting, and guiding so as to introduce into said electromagnetic wave receiver, electromagnetic waves being the reflection of the scanning beam from the scanning target;

a rotor magnet affixed to a lower portion of said rotary unit;

a stator disposed in a position opposing said rotor magnet along its circumference, for imparting rotational drive force to said rotary unit;

a rotational position detector for detecting rotational position of said rotary unit; and

a distance computation circuit connected to said electromagnetic wave receiver and to said rotational position detector, for computing distance to the scanning target based on the electromagnetic wave signal received by said electromagnetic wave receiver.

13. A scanning rangefinder comprising:

an outer cover in fixed form, a transparent window being formed in a circumferential wall portion of said outer cover;

a cylindrical rotary unit arranged inside said outer cover, said cylindrical rotary unit defining a circumferential wall and driven rotationally about a rotational axis;

an optical-beam emitting projector arranged inside the cylindrical rotary unit and having an optical emission source, said projector for emitting a scanning optical beam directed by the rangefinder onto a scanning target at a radial distance from the rangefinder;

a scanning/receiving window formed in a portion of said circumferential wall of said rotary unit at the same height as said transparent window in said outer cover, for guiding through said transparent window, interiorly into said rotary unit, light reflected from the scanning target;

a stationary shaft piece positioned along the rotational axis;

a light receiver disposed on an upper end portion of said stationary shaft piece, for receiving, as a received optical signal, light reflected from the scanning target;

a dual-use mirror disposed in an upper part of said rotary unit so that the scanning beam output from said beam projector is incident on said dual-use mirror and so as to rotate unitarily with said rotary unit, said dual-use mirror therein functioning both as a scanning mirror for reflecting the scanning beam from said beam projector radially outward of said rotary unit to direct the beam onto the scanning target, and as a receiving mirror for reflecting, and guiding so as to introduce into said light receiver, light being the reflection of the scanning beam from the scanning target;

a rotor magnet affixed to a lower portion of said rotary unit;

a stator disposed in a position opposing said rotor magnet along its circumference, for imparting rotational drive force to said rotary unit;

a rotational position detector for detecting rotational position of said cylindrical rotary unit; and

a distance computation circuit connected to said light receiver and to said rotational position detector, for computing distance to the scanning target based on the optical signal received by said light receiver.

14. A scanning rangefinder as set forth in claim 13, wherein information obtained from said light receiver and information output by said rotational position detector is transmitted to said distance computation circuit through the interior of said stationary shaft piece.

15. A scanning rangefinder as set forth in claim 14, further comprising:

a scanning optical system for guiding the beam-projector emitted beam along the rotational axis to said dual-use mirror; and

a receiving optical system for concentrating superficially onto said light receiver, along the rotational axis, received light reflected by said dual-use mirror;

wherein

at least one of said scanning optical system and said receiving optical system is accommodated within a space formed below said dual-use mirror and above said stationary shaft piece.

16. A scanning rangefinder as set forth in claim 13, wherein said rotational position detector is a rotary-angle-detecting resolver.

17. A scanning rangefinder as set forth in claim 13, further comprising a zero calibrator inside said outer cover, for gauging to a standard length inside the rangefinder while in a reverse-detecting mode.

18. A scanning rangefinder as set forth in claim 13, further comprising a photoabsorber-based noise calibrator inside said outer cover.

19. A scanning rangefinder as set forth in claim 13, wherein said optical emission source for said optical-beam emitting projector is one selected from a laser and an LED.

20. A scanning rangefinder comprising:

a rotary unit driven rotationally about a rotational axis;

a stationary shaft piece positioned along the rotational axis;

an optical-beam emitting projector situated on an inner wall of the rotary unit and having an optical emission source, said projector for emitting a scanning optical beam directed by the rangefinder onto a scanning target at a radial distance from the rangefinder;

a light receiver disposed on an upper end portion of said stationary shaft piece, for receiving, as a received optical signal, light reflected from the scanning target;

an optical system including a scanning mirror, said optical system arranged in said rotary unit for reflecting with said scanning mirror the beam from said beam projector and guiding the beam along the rotational axis of said rotary unit;

a dual-use mirror disposed in an upper part of said rotary unit so that the scanning beam output from said beam projector is incident on said dual-use mirror and so as to rotate unitarily with said rotary unit, said dual-use mirror therein functioning both as a scanning mirror for reflecting the scanning beam from said beam projector radially outward of said rotary unit to direct the beam onto the scanning target, and as a receiving mirror for reflecting, and guiding so as to introduce into said light receiver, light being the reflection of the scanning beam from the scanning target;

a receiving lens arranged in between the dual-use mirror and the light receiver;

a rotor magnet affixed to a lower portion of said rotary unit;

a stator disposed in a position opposing said rotor magnet along its circumference, for imparting rotational drive force to said rotary unit;

a rotational position detector for detecting rotational position of said rotary unit; and

a distance computation circuit connected to said light receiver and to said rotational position detector, for computing distance to the scanning target based on the optical signal received by said light receiver.

21. A scanning rangefinder as set forth in claim 20, wherein said optical-system scanning mirror is situated above said receiving lens.

22. A scanning rangefinder as set forth in claim 20, wherein said optical-system scanning mirror is situated below said receiving lens.

23. A scanning rangefinder as set forth in claim 20, wherein said receiving lens has a clearance hole for passing the scanning beam reflected by said dual-use mirror.

24. A scanning rangefinder as set forth in claim 20, wherein information obtained from said light receiver and information output by said rotational position detector is transmitted to said distance computation circuit through the interior of said stationary shaft piece.

25. A scanning rangefinder as set forth in claim 20, wherein said rotational position detector is a rotary-angle-detecting resolver.

26. A scanning rangefinder as set forth in claim 20, wherein said optical emission source for said optical-beam emitting projector is one selected from a laser and an LED.

27. A scanning rangefinder comprising:

a cylindrical rotary unit driven rotationally about a rotational axis;

a stationary shaft piece positioned along the rotational axis;

an optical-beam emitting projector situated on said stationary shaft piece and having an optical emission source, said projector for emitting a scanning optical beam directed by the rangefinder onto a scanning target at a radial distance from the rangefinder;

a light receiver disposed on an upper end portion of said stationary shaft piece, for receiving, as a received optical signal, light reflected from the scanning target;

a dual scanning/receiving mirror disposed in an upper part of, and rotating unitarily with, said cylindrical rotary unit, said scanning/receiving mirror having a scanning mirror section anchored to the rotary unit at a predetermined angle so that the scanning beam output from said beam projector is incident on said scanning mirror section and said scanning mirror section functions to reflect the scanning beam from said beam projector radially outward of said rotary unit to direct the beam onto the scanning target, and said scanning/receiving mirror having a receiving mirror-lens section configured so that said receiving mirror-lens section functions to reflect and focus, and guide so as to introduce into said light receiver, light being the reflection of the scanning beam from the scanning target;

a rotor magnet affixed to a lower portion of said rotary unit;

a stator disposed in a position opposing said rotor magnet along its circumference, for imparting rotational drive force to said rotary unit;

a rotational position detector for detecting rotational position of said rotary unit; and

a distance computation circuit connected to said light receiver and to said rotational position detector, for computing distance to the scanning target based on the optical signal received by said light receiver.

28. A scanning rangefinder as set forth in claim 27, wherein information obtained from said light receiver and information output by said rotational position detector is transmitted to said distance computation circuit through the interior of said stationary shaft piece.

29. A scanning rangefinder as set forth in claim 27, wherein said rotational position detector is a rotary-angle-detecting resolver.

30. A scanning rangefinder as set forth in claim 27, wherein said optical emission source for said optical-beam emitting projector is one selected from a laser and an LED.