Absolute position encoder with coding element having absolute and incremental symbol patterns in parallel - has detector with sensors for recording two symbol patterns and discriminates relative phase position of encoder and detector

摘要

A single track absolute symbol pattern (P) on a coder element (A) is monitored by two groups of sensors (E1-E4,F1-F4), and a number sequence 0000101100111101 is formed by two types of minimal read units with a length lambda. The incremental symbol pattern (I) with arranged alternating divisions or read units is arranged parallel to a further symbol pattern (A), the repeated period of which in this case is equal to the length lambda. A detector (B) is provided with a first group of sensors (E1-E4) and a second such group (F1-F4), which are arranged with a grid dimension lambda and are phase-displaced with a phase difference corresp. to lambda/2 in relation to the first group of sensors. A discriminator switch circuit (C) receives the somewhat triangular waveform output signals from the sensors (S1,S2) as sine and cosine waves, compares the two waves, and then discriminates in real time which of the eight phase positions in each grid dimension lambda corresponds to the phase relation between the coder element and the detector. ADVANTAGE - Miniaturised absolute encoder using single track absolute symbol pattern, in which wirings and connections are simplified.