A ring electrode to determine the orientation of the stylus relative to the surface. The stylus can include a ring electrode configuration which can improve capacitive coupling between the ring electrode and the touch panel. The ring electrode configuration can include a ring electrode and ground ring, and ground plate. By varying the lengths of ring electrode, ground ring, ground plate, and the distance between these elements, the electric field emanating from the ring electrode can be tuned to optimize the capacitive coupling between the ring electrode and surface. In some examples, the ring electrode can include multiple sub-rings. In some examples, the ring electrode can comprise a crown shape including projections, each having a width that tapers to a minimum width along the length of the ring electrode.

A variable capacitor, including: two movable plates, two poles, and one rotary shaft. The two movable plates are conductor belts, and the conductor belts are sheathed in insulators. The two poles are conductors, and each is capable of rotating around an axis thereof. First ends of the two movable plates are connected via the insulators and fixed on the rotary shaft, and second ends of the two movable plates are connected to the two poles, respectively. A conductor member of the two movable plates directly contacts the two poles. The lengths of the two movable plates are identical, and are greater than the distance from one pole to the rotary shaft.

A variable capacitor, including: two movable plates, two poles, and one rotary shaft. The two movable plates are conductor belts, and the conductor belts are sheathed in insulators. The two poles are conductors, and each is capable of rotating around an axis thereof. First ends of the two movable plates are connected via the insulators and fixed on the rotary shaft, and second ends of the two movable plates are connected to the two poles, respectively. A conductor member of the two movable plates directly contacts the two poles. The lengths of the two movable plates are identical, and are greater than the distance from one pole to the rotary shaft.

A ring electrode to determine the orientation of the stylus relative to the surface. The stylus can include a ring electrode configuration which can improve capacitive coupling between the ring electrode and the touch panel. The ring electrode configuration can include a ring electrode and ground ring, and ground plate. By varying the lengths of ring electrode, ground ring, ground plate, and the distance between these elements, the electric field emanating from the ring electrode can be tuned to optimize the capacitive coupling between the ring electrode and surface. In some examples, the ring electrode can include multiple sub-rings. In some examples, the ring electrode can comprise a crown shape including projections, each having a width that tapers to a minimum width along the length of the ring electrode.