Optical rotary encoder

An optical rotary encoder comprising:

• an enclosure having a front wall provided with a central opening therethrough, and a printed circuit board on a rear wall thereof facing opposite the front wall;
• an inner shaft and an outer shaft, said shafts being arranged concentrically with respective operating ends disposed outwardly of the front wall and respective inward ends disposed within the enclosure, said operating ends of the two shafts each being individually rotatably about a common rotation axis;
• a first code plate fixed to an inward end of the inner shaft, and a second code plate fixed to an inward end of the outer shaft parallel to and axially spaced from the first code plate, said second code plate having a larger diameter than the first code plate such that a peripheral portion thereof is disposed radially outwardly of the first code plate;
• a control pulse generator of an optical reflecting rotary encoder type composed of the first code plate having reflecting and non-reflecting indicia formed alternately and circumferentially on one side thereof facing the printed circuit board;
• a reflection type optical detecting element having a light emitting and a light receiving element integrally arranged on the printed circuit board facing opposite said the side of the first code plate;
• a selector switch of an optical transmitting rotary encoder type composed of the second code plate having a plurality of light transmitting apertures formed circumferentially through the peripheral portion of the second code plate;
• a transmitting type optical detecting element having a light emitting element disposed on one side axially of the peripheral portion of the second code plate and a light receiving element disposed on the other side axially of the peripheral portion facing opposite the light emitting element with the peripheral portion of the second code plate disposed therebetween, one of said light emitting and detecting elements for the selector switch being also arranged on the same printed circuit board with the reflection type optical detecting element of the control pulse generator.