Shaft position transducer

A shaft position transducer adapted to be mounted on a shaft comprising

• a bushing carrying a rotary scale means in the form of a gear having a plurality of equally spaced gear teeth and with the top surface of the gear teeth having light characteristics of one kind and the areas between the teeth having light characteristics of another kind,
• a housing constructed of two pieces adapted to be secured together for enclosing the bushing and the rotary scale means, one housing piece having an internally constructed circular opening for permitting the rotary scale to rotate in one housing piece and to be completely enclosed within the internal circular opening of said one housing piece, said housing pieces having a central aperture for mounting the bushing therein,
• a pair of cavities for mounting a light sensing package in each of the cavities defined on the inside surface of the housing in said one housing piece at a location spaced radially outwardly of the circular opening for the rotary scale, each cavity having a small opening communicating with the circular opening of said one housing piece,
• a light sensing package having a light source and a light sensor arranged in a side-by-side relationship in the package and adapted to be snugly mounted in and retained in the circuit package cavity in a preselected nonmovable position, one of said packages being mounted in each of the cavities and being retained therein without possibility of movement when in use, the light sensing packages being further defined to permit the light rays emitted from each of said light sources to impinge on the rotary scale by being conveyed thorugh the individual small opening and be reflected therefrom and being reconveyed through said small opening to impinge on the light sensor for providing electrical analog signals representative of the successive gear teeth when the top surfaces of the rotary scale means rotates past each of said small openings.