Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1993-10-08
1995-01-31
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
318444, H01J 516
Patent
active
053861116
ABSTRACT:
An optical detection system for detecting rain or other water droplets on the outer surface of a window and fog on the inner surface with a single photo-detector. The invention measures the accumulation of water droplets on the window by light refraction of a first light beam with droplets to redirect a first light beam to the photo-detector. A masking device prevents light from reaching the photo-detector directly without refraction. As a result the rain measurement output signal of the photo-detector increases with an increasing accumulation of water droplets on the window. The fog accumulation is measured by a second light beam reflected off the inner surface of the window to the photo-detector so that the output signal of the photo-detector decreases with increasing amounts of fog since fog scatters the light to reduce the amount of light reflected to the photo-detector. A third light source is focused directly on the photo-detector to bias it into an operating point of high sensitivity to infrared light and is connected in a negative feedback circuit from the output of the photo-detector amplifier. The photo-detector output is connected to a narrowband amplifier that is tuned to the frequency of an oscillator which pulses the first and second light sources at different times. As a result of this negative feedback, changes in the output signal due to external factors are cancelled so they do not produce errors.
REFERENCES:
patent: 3487492 (1970-01-01), Bischoff
patent: 3649898 (1972-03-01), Inoue
patent: 3826979 (1974-07-01), Steinmann
patent: 3864659 (1975-02-01), Furuuchi et al.
patent: 4010383 (1977-03-01), Grassmann
patent: 4127763 (1978-11-01), Roselli
patent: 4131834 (1978-12-01), Blaszkowaski
patent: 4317073 (1982-02-01), Blaszkowski
patent: 4355271 (1982-10-01), Noack
patent: 4463294 (1984-07-01), Gibson
patent: 4481450 (1984-11-01), Watanabe et al.
patent: 4499410 (1985-02-01), Iacoponi et al.
patent: 4554493 (1985-11-01), Armstrong
patent: 4589771 (1986-05-01), Watanabe et al.
patent: 4595866 (1986-06-01), Fukatsu et al.
patent: 4620141 (1986-10-01), McCumber et al.
patent: 4636698 (1987-01-01), Leclercq
patent: 4665351 (1987-05-01), Nyberg
patent: 4676638 (1987-06-01), Yasuda
patent: 4810022 (1989-03-01), Takagi et al.
patent: 4859867 (1989-08-01), Larson et al.
patent: 4867561 (1989-09-01), Fujii et al.
patent: 4916374 (1990-04-01), Schierbeek et al.
patent: 4956591 (1990-09-01), Schierbeek et al.
patent: 4960996 (1990-10-01), Hochstein
patent: 4970122 (1990-11-01), Palanisamy
patent: 5015931 (1991-05-01), Muller
patent: 5059877 (1991-10-01), Teder
patent: 5306992 (1994-04-01), Droge
"Tech Briefs", Automotive Engineering, Aug. 1991, p. 44.
Nelms David C.
Nichols Steven L.
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