Optically multiplexed encoder system

Claim 1

In a digital encoder having an encoding member bearing a first group of tracks, at least one track having light transmissive coded segments therein of relatively high spacial frequency and a second group of coarser binary code tracks relative to the tracks in said first group having segments therein of relatively low spatial frequency, the improvement comprising: first track illumination means for continuously directing light at said first group of tracks; first light detector means for detecting light modulated by said first group of tracks and for continuously producing an output signal for each track within said first group of tracks; second track illumination means for sequentially directing light at each track within said second group of tracks in sequence; coarse track data storage latching means having an input circuit; coarse track second light detector means coupled to said input circuit of said coarse track data storage latching for sequentially transmitting coded data associated with said second group of tracks to said data storage latching means; and means for reading said coded data stored within said data storage latching means along with said output signals produced by said first light detector means to establish the position of said encoding member relative to said first and second light detector means.