초록 ▼

A rotor disk or color wheel received on a shaft to be sensed has an annular band of dual color (red/green) filter material having opposite circumferential gradient. A printed circuit board on one axial side of the rotor disk has the dual color LED, emitting light to a reflector on the opposite axial

A rotor disk or color wheel received on a shaft to be sensed has an annular band of dual color (red/green) filter material having opposite circumferential gradient. A printed circuit board on one axial side of the rotor disk has the dual color LED, emitting light to a reflector on the opposite axial side of the rotor disk. Some reflected light from the LED passes through the filter which transmits, according to the amount of single color filter material present at the particular rotor station to a photodetector on the circuit board. Other rays of the emitted light are reflected directly to a second detector for ambient compensation. The amount of light transmitted by the filter causes the detector current to vary the charge rate of a capacitor charged to a reference level, and when reached the LED is switched to the other of the dual color emission. The time required to charge the capacitor to the reference level determines the fraction of the duty cycle of the output signal which may be correlated with known data on the color gradient to determine the rotor angular position. A second color wheel is indexed or geared up or down as an integrator for counting the number of full revolutions of the shaft color wheel.

대표청구항 ▼

[What is claimed is:] [1.](a) a rotor disposed for rotation on a housing structure, said rotor having at least a portion thereof formed of color filtering material having transmittances of two discrete chromaticities disposed in a color gradient in a circumferential direction, said rotor having an a

[What is claimed is:] [1.](a) a rotor disposed for rotation on a housing structure, said rotor having at least a portion thereof formed of color filtering material having transmittances of two discrete chromaticities disposed in a color gradient in a circumferential direction, said rotor having an annular configuration and adapted to have said shaft received therethrough;(b) a circuit board means disposed adjacent one axial side of said rotor, said circuit board means including a source of light of said two discrete chromaticities, and a photodetector spaced from said source;(c) said housing structure defining a reflective surface disposed adjacent an axial side of said rotor opposite said one side;(d) said source and said detector disposed such that said reflective surface reflects light from said source through said color gradient filter and filtered light is transmitted therefrom directly to said detector; and,(e) said circuit board means including circuit means operative to provide a signal indicative of the proportion of transmitted light of one chromaticity.