Patent ID: 8124928

Claim:
An optical encoder system for measuring the rotary angle of a shaft rotatable about a rotary axis, comprising: first and second pattern arrays operatively associated with said shaft to rotate therewith about said rotary axis; said first and second pattern arrays being concentric to each other and to said rotary axis of the shaft; each of said pattern arrays including alternating segments of different optical properties; first and second light guides fixed with respect to said shaft concentric to each other and to said rotary axis of the shaft on one side of said first and second pattern arrays; each of said light guides being of bell-shape, having a small diameter end serving as a light entry surface and a light exit surface for its respective light guide, and a large diameter end having transit surfaces aligned with one of said pattern arrays; light emitters for transmitting light into said small diameter ends of said light guides; and light sensors for sensing light exiting from said small diameter ends of said light guides; characterized in that said light emitters and light sensors are carried by an electronic board interposed between said small diameter ends of the first and second light guides, with one face of the electronic board carrying a light emitter and a light sensor for said first light guide, and the opposite face of the electronic board carrying a light emitter and a light sensor for said second light guide.