Position sensing apparatus

摘要

Position sensing apparatus comprising two coil arrangements movable relative to each other, the first arrangement being a side-by-side array of elongate coil loops defining a writing area and the second coil arrangement being a single or multiple coil loose coupled with the coil loops in the array. The coil loops in the side-by-side array have phase-shifting units between them so that they give an output which is unambiguously and progressively phase-characterized dependent upon the position of the second coil arrangement on the writing area in the direction of the array. Two layers of the elongate coil loops can be provided so that the coil loops in one layer are at right angles to those in the other to give "x" or "y" co-ordinate positioning. The phase shift over the writing area may be less than 360 DEG , or greater than 360 DEG with the use of an ambiguity eliminating circuit. The second coil arrangement may comprise two coils carried on a pen and spaced from the pen tip and connected so that indefiniteness does not arise as the pen is tilted. Apparatus according to the invention may have its output processed for line transmission for stock ordering and accounting purposes or for signature verification.