| 摘要 |
<p>PURPOSE:To contrive the high speed of coordinate read in a tablet type input device by detecting a sense coil, which has generated an inductive voltage over a reference voltage value fixed beforehand, A/D-converting the inductive voltage of the sense coil, and reading a coordinate position designated by means of an input pen. CONSTITUTION:A ladder type D/A converting circuit 7, in which the network of a resistor is formed to a ladder shape, and a comparator 8, which compares the inductive voltage of sense coils 2a and 2b from a rectifying circuit 6 with the output voltage from the ladder type D/A converting circuit 7, are provided. Further a comparative type A/D converting circuit 11 attached with an MPU 9, which outputs digital data to the ladder type D/A converting circuit 7 and to which the output of the comparator 8 is applied, and a memory 10 is provided. The sense coils 2a and 2b, which have generated the inductive voltage larger than the reference voltage fixed beforehand, are detected, the inductive voltages of the detected sense coils 2a and 2b are A/D-converted, and the coordinate position designated by an input pen 1 is calculated. Thus the coordinate can be read faster compared with the read by the conventional device which A/D-converts the inductive voltages of the all sense coils 2a and 2b.</p> |
