Pen state detection circuit, system, and method

A pen state detection circuit that detects a state of an electronic pen including a first electrode, on a basis of a signal distribution detected by a capacitance touch sensor including a plurality of sensor electrodes arranged in a plane shape,

• the pen state detection circuit executing:
• an acquisition step of acquiring, from the touch sensor, a first signal distribution indicating a change in capacitance associated with approach of the first electrode, and
• an estimation step of using a machine learning estimator to estimate an instruction position or an inclination angle of the electronic pen from first feature values related to the first signal distribution,
• wherein
• the first feature values include first local feature values related to a first local distribution corresponding to sensor electrodes in a number fewer than the number of arranged sensor electrodes exhibiting the first signal distribution, and
• in the estimation step, the instruction position or the inclination angle is estimated by using the machine learning estimator in which different learning parameter groups are set according to whether the electronic pen is in a contact state or a hover state.