Distance measurement apparatus

• US 9,316,495 B2
• Filed: 08/08/2013
• Issued: 04/19/2016
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Suzuki, Shuichi, Yoshimura, Kenichi, Nakajima, Mitsuru, Hayashi, Yusuke
• Primary Examiner(s): Ratcliffe, Luke
• Application Number:
  US13/962,196
• Publication Number:
  US 20140071428A1
• Time in Patent Office: 985 Days
• Field of Search: 356 301- 515
• US Class Current: 1/1
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/00 Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates

Abstract

A distance measurement apparatus that measures distance to a target by irradiating the target with laser beams and detecting light reflected by the target includes a light projection unit. The distance measurement apparatus also includes a plurality of light emission units to emit a plurality of laser beams onto the target while setting optical paths of the plurality of laser beams radially along a given virtual plane; and a light receiving unit including a plurality of light receivers to receive the plurality of laser beams projected from the light projection unit and reflected by the target.

Claims

1. A distance measurement apparatus to measure distance to a target by irradiating laser beams to the target and receiving a reflection light reflected from the target, the distance measurement apparatus comprising:

a light projection unit including a plurality of light emission units to project a plurality of laser beams onto the target while setting optical paths of the plurality of laser beams radially along a given virtual plane, each of the light emission units including a light source and a projection optical system disposed on an optical path of the laser beam emitted from the light source; and

a light receiving unit including a plurality of light receivers to receive the plurality of laser beams, projected from the light projection unit and reflected by the target, each one of the plurality of light receivers provided for a corresponding one of the plurality of light emission units,

wherein the plurality of light receivers is disposed separately in a direction perpendicular to the virtual plane with respect to the corresponding plurality of light emission units,

wherein each of the plurality of light receivers includes a light receiving element provided for the light source of the corresponding light emission unit, and a light condensing system to condense laser beams, projected from the corresponding light source and reflected by the target, onto the light receiving element,

wherein each of the light receiving elements includes a plurality of light receiving portions arranged along one axis direction parallel to the virtual plane,

wherein the light condensing system includes a first cylindrical lens and a second cylindrical lens,

wherein the first cylindrical lens condenses laser beams to a direction perpendicular to the one axis direction, and

the second cylindrical lens, disposed separately with respect to the first cylindrical lens in a direction parallel to an exit direction of the corresponding light source, condenses the laser beams to the one axis direction.

2. The distance measurement apparatus of claim 1, wherein each of the plurality of laser beams projected from the light projection unit has a given divergence angle along the virtual plane.

3. The distance measurement apparatus of claim 2, wherein the divergence angle ranges from 20 degrees to 40 degrees.

4. The distance measurement apparatus of claim 1, wherein the exit directions of the light sources of the plurality of light emission units are not parallel to each other.

5. The distance measurement apparatus of claim 1, wherein the light projection unit further includes a deflector disposed on optical paths of laser beams emitted from the plurality of light emission units via the projection optical system, and the deflector deflects the laser beams along the virtual plane.

6. The distance measurement apparatus of claim 5, wherein the deflector is a deflection element formed with a blazed grating on at least one of an incidence face and an exit face of the deflection element.

7. The distance measurement apparatus of claim 5, further comprising a casing and a light-permeable window member,

wherein the casing encases the light projection unit and the light receiving unit,

wherein the light-permeable window member is provided to the casing while positioned on optical paths of a plurality of laser beams emitted from the plurality of light emission units,

wherein the deflector is a blazed grating formed on the light-permeable window member.

8. The distance measurement apparatus of claim 1, wherein the plurality of light emission units and the corresponding plurality of light receivers are integrated into a single unit.

9. The distance measurement apparatus of claim 1, wherein the second cylindrical lens is disposed closer to the light receiving element than is the first cylindrical lens.

14. The distance measurement apparatus of claim 1, further comprising a distance computing circuit that computes distance to a plurality of portions of the target in the one axis direction based on emission timing of the light source and light receiving timing at each of a plurality of light receiving portions of the corresponding light receiving element.

15. The distance measurement apparatus of claim 1, wherein the projection optical system includes a cylindrical lens, disposed on optical paths of laser beams emitted from the light source, to diffuse light in a direction along the virtual plane.

16. The distance measurement apparatus of claim 15, wherein the projection optical system includes a coupling lens, disposed on optical paths of laser beams between the light source and the cylindrical lens, to set the laser beams to substantially parallel.

10. A distance measurement apparatus to measure distance to a target by irradiating laser beams to the target and receiving a reflection light reflected from the target, the distance measurement apparatus comprising:

a light projection unit including a plurality of light emission units to project a plurality of laser beams onto the target while setting optical paths of the plurality of laser beams radially along a given virtual plane, each of the light emission units including a light source and a projection optical system disposed on an optical path of the laser beam emitted from the light source; and

a light receiving unit including a plurality of light receivers to receive the plurality of laser beams, projected from the light projection unit and reflected by the target, each one of the plurality of light receivers provided for a corresponding one of the plurality of light emission units,

wherein the plurality of light receivers is disposed separately in a direction perpendicular to the virtual plane with respect to the corresponding plurality of light emission units

wherein each of the plurality of light receivers includes a light receiving element provided for the light source of the corresponding light emission unit, and a light condensing system to condense laser beams, projected from the corresponding light source and reflected by the target, onto the light receiving element,

wherein each of the light receiving elements includes a plurality of light receiving portions arranged along one axis direction parallel to the virtual plane,

wherein the light condensing system has a condensing element having an incidence face and an exit face,

wherein the first cylindrical face is formed on one of the incidence face and the exit face to condense laser beams in a direction perpendicular to the one axis direction, and

wherein the second cylindrical face is formed on the other one of the incidence face and the exit face to condense the laser beams in the one axis direction.

11. The distance measurement apparatus of claim 10, wherein the first cylindrical face is formed on the incidence face, and the second cylindrical face is formed on the exit face in the light condensing system.

12. A distance measurement apparatus to measure distance to a target by irradiating laser beams to the target and receiving a reflection light reflected from the target, the distance measurement apparatus comprising:

a light projection unit including a plurality of light emission units to project a plurality of laser beams onto the target while setting optical paths of the plurality of laser beams radially along a given virtual plane, each of the light emission units including a light source and a projection optical system disposed on an optical path of the laser beam emitted from the light source; and

a light receiving unit including a plurality of light receivers to receive the plurality of laser beams, projected from the light projection unit and reflected by the target, each one of the plurality of light receivers provided for a corresponding one of the plurality of light emission units,

wherein the plurality of light receivers is disposed separately in a direction perpendicular to the virtual plane with respect to the corresponding plurality of light emission units,

wherein each of the plurality of light receivers includes a light receiving element provided for the light source of the corresponding light emission unit, and a light condensing system to condense laser beams, projected from the corresponding light source and reflected by the target, onto the light receiving element,

wherein each of the light receiving elements includes a plurality of light receiving portions arranged along one axis direction parallel to the virtual plane,

wherein the light condensing system has a condensing element formed with a blazed grating on an exit face of the condensing element to condense laser beams in a direction perpendicular to the one axis direction.

13. The distance measurement apparatus of claim 12, wherein the condensing element is formed with a cylindrical face on the incidence face of the condensing element to condense laser beams in the one axis direction.