Title:
【発明の名称】長距離測距センサ
Document Type and Number:
Japanese Patent JP2685922
Kind Code:
B2
Abstract:
PURPOSE:To obtain high distance measuring accuracy by providing a second mixing circuit and a filter part, and forming a phase-difference detecting signal based on the output of a PLL circuit. CONSTITUTION:An optical beam from a light emitting element 3 is reflected from a mirror 4. The reflected light is received with a photodetector 4. The output signal from a phase-difference detecting part 11 is stored as a phase difference data. Then, the reflected light of the optical beam from a body to be detected X is received 4. The phase difference signal from the detecting part 11 at this time is compared with the phase difference data which have been stored before. The phase difference signal where in the phase change caused by the circuit system is offset is sent into a distance decision part 12 as a distance signal. Thus the distance to the body X is decided. At this time, the output frequency of a frequency converting part comprising a second mixer circuit 7 and a filter part 9 becomes always equal to the frequency of a filter part 10. The output of a PLL circuit 6 is not integrated in the detecting part 11. Therefore, the error of the distance signal outputted from the detecting part 11 is only the error caused by the fluctuation of the oscillated frequency of the circuit 6 when the internal noises in the circuit are removed. Thus the high distance measuring accuracy is obtained.
Inventors:
Hiroshi Matsuda
Yuji Takada
Yuji Takada
Application Number:
JP25010489A
Publication Date:
December 08, 1997
Filing Date:
September 26, 1989
Export Citation:
Assignee:
MATSUSHITA ELECTRIC WORKS,LTD.
International Classes:
G01C3/06; G01C1/02; G01R25/00; G01S17/08; G01S17/36; H03D13/00; (IPC1-7): G01S17/36; G01R25/00; H03D13/00
Domestic Patent References:
| JP6287874A | ||||
| JP6066167A | ||||
| JP46101486A | ||||
| JP2184787A |
Attorney, Agent or Firm:
Ishida Chochichi (2 outside)