Absolute position encoding system - has scales on encoder for coarse capacitive and fine optical measurements, and digitises results for processing by counter and comparator circuit

摘要

The encoding system has a linear scale with a coarse resolution capacitive pattern and a high resolution optical pattern. The capacitive and optical scales are sensed (20,50) by corresponding detectors, and relative switching stages provide digital signals. The absolute capacitive values are entered into a register (40) and combined with the optical values in a bi-directional counter unit (90). A reset pulse generator (140) provides an output to a latch (110) coupled to a shift register (120). A comparator (100) identifies any error condition. ADVANTAGE - Improved reset process.