Position detection device and control method for position detection sensor

A control method for a position detection sensor which is used for a position detection device, the position detection device having a main body with a housing including an accommodation portion that accommodates therein an electronic pen having a position indication coil wound in an axial direction of the electronic pen, the housing of the main body of the position detection device enclosing the electronic pen while the electronic pen is accommodated in the accommodation portion, a planar coil having a rectangular cross-sectional area and disposed adjacent to the accommodation portion and disposed at a position at which a direction perpendicular to the rectangular cross-sectional area of the planar coil crosses the axial direction of the electronic pen while the electronic pen is accommodated in the accommodation portion, the planar coil extending substantially in parallel to the axial direction of the electronic pen while the electronic pen is accommodated in the accommodation portion, the planar coil having a rectangular cross-sectional area, the planar coil extending longitudinally in the axial direction of the electronic pen while the electronic pen is accommodated in the accommodation portion, and a first number of magnetic fluxes, from among magnetic fluxes generated by the planar coil, interlinking in a first direction with the position indication coil of the electronic pen is not equal to a second number of magnetic fluxes, from among the magnetic fluxes generated by the planar coil, interlinking in a second direction with the position indication coil of the electronic pen, the first direction being opposite the second direction, and the position detection sensor including a plurality of first loop coils disposed in a first direction and a plurality of second loop coils disposed in a second direction crossing the first direction and configured to detect a position indicated by the electronic pen in an operation region, the planar coil being disposed outside of the operation region in which the position indicated by the electronic pen is detectable by the position detection sensor, the control method comprising:

• performing a first control process that includes alternately supplying a first signal to the planar coil and receiving a second signal through the planar coil by electromagnetic induction;
• detecting a state regarding accommodation of the electronic pen in the accommodation portion in accordance with a presence or an absence of the second signal received through the planar coil extending substantially in parallel to the axis of the electronic pen while the electronic pen is accommodated in the accommodation portion;
• performing a second control process that includes specifying a first loop coil which is to transmit a third signal from among the plurality of first loop coils and the plurality of second loop coils and supplying the third signal to the specified first loop coil, specifying a second loop coil which is to receive a fourth signal from among the plurality of first loop coils and the plurality of second loop coils, and receiving the fourth signal through the specified second loop coil;
• detecting the position indicated by the electronic pen on the position detection sensor based on the fourth signal received through the specified second loop coil;
• and
• controlling, while detecting that the electronic pen is accommodated in the accommodation portion, to not perform the second control process and the detecting of the position indicated by the electronic pen through the position detection sensor.