Photosensitive position sensor

Abstract

Abstract A position sensor has a photosensitive element including a pn junction formed between first and second electrodes for providing first and second photocurrents varying in dependence on the position of an illuminated spot between the first and second electrodes, and a processing circuit including an current converting circuits for producing first and second detection currents corresponding to the first and second photocurrents, a first sum current equal to a sum of the first detection current and twice the second detection current and a second sum current equal to a sum of the second detection current and twice the first detection current, a logarithmic converting circuit for producing first, second, third and fourth voltages which are in logarithmic relationships with the first detection current, the first sum current, the second sum current and the second detection current, respectively, differential circuits for producing first and second differential output currents from a difference between the first and second voltages and third and fourth differential output currents from a difference between the third and fourth voltages, and an operating circuit for producing a position signal representing the position of the illuminated spot from the differential output currents.

Inventors

• 👤 Hideo Muro

Bibliographic Details