Object detector and sensor

• US 9,817,123 B2
• Filed: 12/07/2016
• Issued: 11/14/2017
• Est. Priority Date: 12/06/2013
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Akatsu, Kazuhiro, Nakamura, Tadashi, Sakai, Kohji
• Primary Examiner(s): Sohn, Seung C
• Application Number:
  US15/371,650
• Publication Number:
  US 20170082747A1
• Time in Patent Office: 342 Days
• Field of Search: 250221, 356 501, 340435
• 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 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4868 Controlling received signal intensity or exposure of sensor
• CPC Class Codes: G01S 7/51 Display arrangements
• CPC Class Codes: H05B 47/115 by determining the presence or movement of objects or living beings
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

An object detector includes a projector including a light source having a two-dimensionally arranged plurality of light emitter groups, ach of the light emitter groups having a plurality of light emitters, a light receiver which receives light emitted from the projector, and reflected by an object, and a light source driver which lights on and lights off each of the light emitter groups of the light source.

Claims

1. An object detector, comprising:

a projector including a light source having a two-dimensionally arranged plurality of light emitter groups, each of the light emitter groups having a plurality of light emitters;

a light receiver which receives light emitted from the projector, and reflected by an object;

a light source driver which lights on and lights off each of the light emitter groups of the light source; and

a processor which independently and sequentially lights on and lights off the plurality of light emitter groups using the light source driver, and obtains distance information to the object based on lighting-on timing of the light emitter group and light-receiving timing of the light receiver when the light receiver receives light reflected by the object, wherein

the processor simultaneously lights on and lights off at least two light emitter groups among the plurality of light emitter groups until the light receiver receives the light reflected by the object.

2. The object detector according to claim 1, wherein the processor adjusts emission light volume of the light emitter group based on the distance information to the object.

3. The object detector according to claim 1, wherein the processor adjusts the number of light emitters to be lighted on in the light emitter group based on the distance information to the object.

4. The object detector according to claim 1, wherein the processor adjusts driving current to the light emitter group based on the distance information to the object.

5. The object detector according to claim 1, wherein the processor sequentially lights on the light emitter group at least one light emitter group away from a previously lighted-on light emitter group.

6. The object detector according to claim 1, wherein:

the projector includes a projection optical system disposed on an optical path of light emitted from the light source, and

a focal length of the projection optical system is variable.

7. The object detector according to claim 6, wherein:

the projection optical system includes a plurality of optical elements each having a different focal length; and

a driving mechanism which locates one of the plurality of optical elements on the optical path of the light emitted from the light source.

8. The object detector according to claim 6, wherein:

the projection optical system includes an optical system having a zooming operation.

9. The object detector according to claim 1, wherein:

the light receiver includes a single light-receiving element, and

a size of a light-receiving area is the same as a size of an emission area when the plurality of light emitter groups in the light source are simultaneously lighted on.

10. The object detector according to claim 1, wherein:

the light receiver includes a member which transmits only the light reflected by the object.

11. The object detector according to claim 10, wherein:

the member includes an opening which transmits only the light reflected by the object.

12. The object detector according to claim 1, wherein:

the light receiver includes a bandpass filter which transmits only the light reflected by the object.

13. The object detector according to claim 1, wherein:

the plurality of light emitter groups is disposed along a first direction and a second direction orthogonal to each other,

the light receiver includes a light-receiving optical system which collects the light reflected by the object, and

the light-receiving optical system has a focal length which differs between the first direction and the second direction.

14. The object detector according to claim 13, wherein:

a size of a sectional shape of light toward tin object in the second direction is larger than a size of a sectional shape of light toward the object m the second direction when the plurality of light emitter groups is simultaneously lighted on, and

a focal distance of the light-receiving optical system in the first direction is shorter than a focal distance of the light-receiving optical system in the second direction.

15. The object detector according to claim 1, wherein:

the light emitter groups arranged in a peripheral part of the plurality of light emitter groups have an emission light volume larger than an emission light volume of the light emitter groups disposed in a central part of the plurality of light emitter groups.

16. The object detector according to claim 15, wherein:

the light emitter groups in the peripheral part of the plurality of light emitter groups have driving current larger than that of the light emitter groups disposed in the central part of the plurality of light emitter groups.

17. The object detector according to claim 15, wherein:

the light emitter groups disposed in the peripheral part of the plurality of light emitter groups have a larger number of light emitters than that of the light emitter groups in the central part of the plurality of light emitter groups.

18. The object detector according to claim 17, wherein;

the processor obtains shape information of the object based on distance information to the object for each of the light emitter groups.

19. A sensor, comprising:

the object detector according to claim 1; and

a monitoring controller which obtains moving information including at least one of existence or non-existence of movement, a moving direction, and a moving speed of the object based on output of the object detector.

20. The sensor according so claim 19 further comprising a display which displays at least one of positional information and moving information of the object.