| 摘要 |
<p>PURPOSE:To identify the state of a position pointing device without carrying out a self-proofreading operation by using the 1st and 2nd phase detection means which detect the phases of voltage induced in the first and second halves of a reception period and a state identification means to form a processor. CONSTITUTION:A position detecting part 1 contains the loop coils 11-1 - 11-48, and the loop coils selected by a selection circuit 2 are connected alternately to a transmission circuit 5 and a reception circuit 6 respectively via a transmission/reception part switch circuit 3. The circuit 6 detects the induced voltage having a frequency approximately equal to the prescribed frequency produced by the loop coil for a reception period. A processor 7 detects the phase of the induced voltage and identifies the state of a position pointing device 4 based on the detected phase. The processor 7 consists of the 1st and 2nd phase detection means which detect the phases of the induced voltage in the first and second halves of a reception period and a state identification means which identifies the state of the device 4 based on the phase detection results of both phase detection means. Thus it is possible to identify the state of the device 4 without carrying out a self-proofreading operation even if an error is produced between the phases of the induced voltage.</p> |
