Rotatable input knob configured to operate on electrostatic capacitive touch panel

A sensor device comprising:

• an electrostatic capacitive touch panel;
• a knob disposed rotatably about a rotation axis;
• a conductor held by the knob and opposed to the touch panel on a part of a circumference about the rotation axis;
• and
• a sensor controller configured to control the touch panel, wherein
• the sensor controller holds a reference signal corresponding to an electrostatic capacitance in a state where the conductor is not opposed to the touch panel,
• the sensor controller is configured to receive a first sensor signal from the touch panel in a state where the conductor is opposed to a first position of the touch panel and to detect first coordinates of the conductor based on the first sensor signal and the reference signal in a first sensing period,
• the sensor controller is configured to:
• receive a second sensor signal from the touch panel in a state where the conductor is opposed to a second position of the touch panel and detect second coordinates of the conductor based on the second sensor signal and the reference signal in a second sensing period,
• calculate a movement distance of the conductor based on the first coordinates and the second coordinates, and
• detect a rotation angle of the conductor based on the movement distance, and
• when the conductor is rotated at a minimum rotation angle θ min to be detected and a reference direct distance between two points between which the conductor is moved is La, if the calculated movement distance is greater than or equal to (La/2) but less than (3*La/2), the sensor controller is configured to detect that the rotation angle is θ min.