Patent ID: 9182872
Filing Date: 2015-11-10
Classification: G06F

Abstract:
1. An indicator position detecting device comprising: a sensor substrate that detects a position indicated by an indicator, the sensor substrate having a plurality of first loop coils disposed in a first direction and a plurality of second loop coils disposed in a second direction intersecting the first direction; a transmission signal generating circuit that generates a transmission signal to be supplied to at least one loop coil of the first loop coils and the second loop coils to effect electromagnetic coupling with the indicator; a received signal processing circuit that receives a signal induced in at least one loop coil of the first loop coils and the second loop coils based on electromagnetic coupling with the indicator, and that detects the position indicated by the indicator; a loop coil selecting circuit that selectively supplies the transmission signal generated by the transmission signal generating circuit to at least one loop coil of the first loop coils and the second loop coils; a control circuit that controls loop coil selection by the loop coil selecting circuit; and a magnetic path plate that forms a magnetic path for a magnetic flux generated by the transmission signal supplied to at least one loop coil of the first loop coils and the second loop coils, the magnetic path plate being disposed so as to be superposed on the sensor substrate; wherein when the transmission signal is supplied to loop coil(s) disposed in at least one direction among the first loop coils disposed in the first direction and the second loop coils disposed in the second direction, the control circuit controls the loop coil selecting circuit so as not to supply the transmission signal to a determined number of loop coil(s) that are disposed in said at least one direction and that are in at least one peripheral region of the sensor substrate along said at least one direction, and the indicator position detecting device further comprises at least one capacitor connected to the determined number of loop coil(s) not supplied with the transmission signal, the at least one capacitor being operable to produce tuned resonance with the transmission signal supplied to the loop coils other than the determined number of loop coil(s).