Touch panel input apparatus performing a sampling operation intermittently

摘要

A touch panel input apparatus has a touch panel which consists of X- and Y-direction electrode panels. When the apparatus is in a power-off state, one end of the X electrode panel is intermittently connected to a power source and one end of the Y electrode panel is intermittently grounded via an output resistor, in response to control signals outputted from a sampling circuit. In this state, synchronously with a clock signal, the sampling circuit performs sampling of a voltage developed across the output resistor when the two electrode panels are brought into contact. The sampling circuit outputs a power-on instruction signal to make the CPU perform the power-on operation. The sampling circuit stops its sampling operation once power is turned on.