Compact optional rotary encoder having adjustable light admitting and receiving components

Claim 1

An optical rotary encoder comprising: a body including a disc-shaped portion, and a cylindrical portion projecting from said disc-shaped portion and defining a cavity, said cylindrical portion including slit means therethrough communicating with said cavity, an end cap closing an end of said cylindrical portion remote from said disc-shaped portion, a first bearing mounted centrally in said disshaped portion, a second bearing mounted centrally in said end cap and being axially slidable therein, axially adjustable retaining means for retaining said second bearing in said end cap and for eliminating axial play of said second bearing, a detection shaft journaled in said first and second bearings, light emitting means mounted in said body, a rotary slit wheel fixed on said detection shaft within said cavity for rotation therewith, said rotary slit wheel including position signaling slits, and at least one original signaling hole, said slits and hole being arranged to oppose said light emitting means, a stationary slit plate disposed within said cavity and including position signaling slits and at least one origin signaling hole, said slits and hole being arranged to oppose said light emitting means, said stationary slit plate opposes a side of said rotary slit wheel opposite said light emitting means such that said rotary slit wheel is disposed between said light emitting means and said stationary slit plate, a printed circuit board disposed within said cavity and including light receiving means for receiving light from said light emitting means which has passed through said position signaling slits and said original signaling holes of said rotary slit wheel and stationary slit plate, a block disc interposed between said stationary slit plate and said circuit board for interconnecting said stationary slit plate and said circuit board, said block disc including holes for admitting light from said position signaling slits and original signaling hole of said stationary slit plate, said block disc, said stationary slit plate and said circuit board being interconnected as a unit for common rotational adjustment by means of an external force applied through said slit means of said cylindrical portion, to adjust the angular position of said unit relative to said rotary slit wheel, and securing means for securing said unit in its adjusted angular positions.