Patent ID: 6930674

Claim:
A position detector comprising: a position indicator comprising a resonant circuit comprising at least a coil and a capacitor; and a tablet for transmitting/receiving electromagnetic waves to/from the position indicator, whereby coordinate values of a position indicated by the position indicator are detected; wherein electromagnetic waves which include predetermined timing information are generated by the tablet; the predetermined timing information is extracted from a dielectric voltage generated at the resonant circuit in the position indicator which has received the electromagnetic waves; a resonance characteristic of the resonant circuit in the position indicator is controlled in accordance with operations at specific times based on the predetermined timing information; and the phase or strength of electromagnetic waves which are generated at the specific times by the resonant circuit in the position indicator is detected; the position indicator further comprises: first resonance characteristic control means for causing the resonance characteristic of the resonant circuit at a first specific time based on the predetermined timing information to be a value within a predetermined variable range of the resonance characteristic in accordance with a continuous operation quantity; second resonance characteristic control means for causing the resonance characteristic of the resonant circuit at a second specific time based on the predetermined timing information to be a maximum within the predetermined variable range of the resonance characteristic; and third resonance characteristic control means for causing the resonance characteristic of the resonant circuit at a third specific time based on the predetermined timing information to be a minimum within the predetermined variable range of the resonance characteristic; and the tablet comprises: detection value obtaining means for obtaining the phase or strength of the electromagnetic waves generated by the resonant circuit in the position indicator at the first, second, and third specific times as first, second, and third detection values, respectively; and processing means for detecting a continuous operation quantity by relating the first detection value to a range from an upper limit to a lower limit, the upper limit being one of the second and third detection values and the lower limit being the other detection value.