Optics: measuring and testing – Range or remote distance finding – With photodetection
Reexamination Certificate
1999-09-20
2001-12-04
Buczinski, Stephen C. (Department: 3662)
Optics: measuring and testing
Range or remote distance finding
With photodetection
C356S141100, C180S169000
Reexamination Certificate
active
06327029
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a range finding device of scanning type used for a system of alerting collisions of a vehicle.
2. Discussion of Background
An example of a conventional range finding device of a scanning type is disclosed in, JP-A-7-84045. In this reference, a range finding device for emitting laser beams in a plurality of directions and receiving reflected light from objects, respectively positioned in emitting directions of the laser beams, in order to respectively measure ranges is disclosed. The device simultaneously scans the plurality of laser beams for measuring the ranges from the objects, respectively positioned in the directions of emitting the laser beams. According to this device, a scanning period is shortened to be one of the number of the plurality of the laser beams and a degree of freedom is increased in designing an optical system.
However, such conventional range finding techniques have problems. For example, a plurality of laser diodes are necessary and thereby the cost is increased.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problem inherent in the conventional technique and to provide a range finding device of scanning type which measures ranges in many directions at a high rate and improves the angular resolution with an uncostly structure.
According to a first aspect of the present invention, there is provided a range finding device of a scanning type comprising a means for emitting a laser beam which emits laser beamn pulses from a single light source and scans by changing a heading angle of the emission, and a range finding means for detecting a range from an object in correspondence with a scanning angle based on a reciprocating time between the emission of the pulses from the means for emitting laser beams and a receipt of the pulses reflected by the object, wherein the means for emitting the laser beam shifts the beam scanning angle of emitting the pulses in each scan.
According to a second aspect of the present invention, there is provided the range finding device of scanning type according to the first aspect of the invention, wherein the amount of beam shift of the scanning angle at a time of emitting the pulses by each scan is a value obtained by dividing the beam intervals of the emitting pulses into equal parts.
According to a third aspect of the present invention, there is provided the range finding device of scanning type according to the first or second aspect of the invention, wherein a direction angle of the object is judged based on detected information in a finished plurality of scans corresponding to the scanning angle obtained by the range finding means.
According to a fourth aspect of the present invention, there is provided the range finding device according to the third aspect of the invention, wherein the direction angle of the object is judged based on most recently detected information being the number equal to that of turning the scanning angle at a time of emitting the pulses in correspondence with the scanning angle.
REFERENCES:
patent: 4632543 (1986-12-01), Endo
patent: 5114226 (1992-05-01), Goodwin et al.
patent: 5682229 (1997-10-01), Wangler
patent: 5760886 (1998-06-01), Miyazaki et al.
patent: 6122040 (2000-09-01), Arita et al.
patent: 7-84045 (1995-03-01), None
Buczinski Stephen C.
Mitsubishi Denki & Kabushiki Kaisha
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