| 摘要 |
A system for encoding position information includes a grid of evenly spaced, parallel conductive lines fixed with respect to one of two mechanical parts, the grid being disposed along the line of movement of the parts. Two pairs of interdigitated electrodes capacitively sense the conductive lines of the grid, the electrodes being fixedly disposed on the other mechanical part. Decoding circuitry is responsive to the electrodes for providing relative movement information. The fingers of each electrode are disposed substantially parallel to the grid lines, the capacitance of each electrode with respect to the grid being a function of the proximity of the fingers of that electrode to the grid lines. The decoding circuitry includes first and second latches whose outputs are a function of which electrode of its corresponding pair has the greater capacitance to the grid. The second pair of interdigitated electrodes is offset from the first pair such that its output differs from that of the first pair. The decoding circuitry further includes circuitry responsive to the output of the latches for determining the direction of travel of the mechanical parts with respect to each other. |
