JPS6453222A - Input pen for coordinate input device - Google Patents

Abstract

PURPOSE:To obtain the information corresponding accurately to the writing pressure with no use of a cable by changing the coil inductance according to the displacement of the core substance of an input pen and then changing the tuning frequency of a tuning circuit consisting of a coil and a capacitor. CONSTITUTION:When the writing pressure is applied to a pen 11, a core substance 12 is displaced toward the axis of the pen 11. At the same time, a ferrite chip 13 is displayed at the end of a coil 14. The permeability of the coil 14 changes in accordance with the displacement value of the coil 14 and the coil inductance changes thereof. Thus the tuning frequency of a tuning circuit consisting of the coil 14 and a capacitor 17 is slightly changed. As a result, the phase and the frequency of the induced voltage set by the radio wave transmitted from a coordinate input device are changed. This displacement value, i.e., the information corresponding to the writing pressure is taken out of the radio waves transmitted from the coil 14 based on the induced voltage set after its change at the side of the coordinate input device. Thus no cable is required to the coordinate input device. In addition, the change of the tuning frequency depends on only the displacement value of the substance 12. Thus it is possible to obtain the accurate information in response to the writing pressure even at any position of a tablet.