Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1984-08-08
1987-03-17
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
250225, 340347P, G02F 101
Patent
active
046509968
ABSTRACT:
An angle transducer which photo-electrically measures the rotation angle of a shaft by utilizing, a polarizer disc is arranged as follows: the polarizer disc is secured to the shaft to be measured or to the detection shaft of the angle transducer. Two pairs of photo-electric conversion elements are in opposition to light sources across the polarizer disc. The first and second polarizer plates are interposed between the photo-electric conversion elements of each pair. The transmission axes of the first and second polarizer plates differ from each other by 45 degrees. The quantities of light emitted by the light sources or the outputs of the photo-electric conversion elements are modulated by carrier waves of two phases differing 90 degrees from each other. The amplitudes of the outputs correspond to the sine and cosine functions of the double angle of the rotation angle of the shaft to be measured. These outputs form modulated waves of two phases differing 90 degrees from each other. The sum of the modulated waves of two phases, and the difference between the sum and a signal obtained by multiplication of the two phase carrier waves by a predetermined value, are computed by addition and subtraction computers to obtain a phase signal of a sine wave the phase of which is proportional to the rotation angle of the shaft being measured.
REFERENCES:
patent: 2966673 (1960-12-01), Guernsey
patent: 3306159 (1967-02-01), Beall et al.
patent: 3397608 (1968-08-01), Ellis
patent: 3687555 (1972-08-01), Yamamoto et al.
patent: 4271354 (1981-06-01), Shellenberger
Maehara Osamu
Nakajima Yoshitaka
Allen S.
Kabushiki Kaisha Ono Sokki
Nelms David C.
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