Patent ID: 8242744
Filing Date: 2012-08-14
Classification: H02J

Abstract:
1. A battery charger comprising: a mounting base on which a compact electric apparatus having a built-in secondary battery is mounted; a charging circuit which supplies a charging power; a detection circuit which detects mounting of the compact electric apparatus on the mounting base; a control circuit which controls the charging circuit to charge the built-in secondary battery when the detection circuit detects mounting of the compact electric apparatus on the mounting base; a charge contact member which has a charge contact electrically connected to a positive terminal of the charging circuit and connected to a positive line of the compact electric apparatus when the compact electric apparatus is mounted on the mounting base to charge the built-in secondary battery of the compact electric apparatus; a common contact member which has a common contact electrically connected to a negative terminal of the charging circuit and the detection circuit and connected to a negative power source line of the compact electric apparatus when the compact electric apparatus is mounted on the mounting base; a signal contact member which has a signal contact and a detection contact and is displaced by contacting with the compact electric apparatus when the compact electric apparatus is mounted on the mounting base, the signal contact being electrically connected to the detection circuit and the control circuit and connected to a control signal line of the compact electric apparatus when the compact electric apparatus is mounted on the mounting base, and the detection contact electrically connecting the signal contact member to the common contact member when the compact electric apparatus is not mounted on the mounting base, and electrically disconnecting the signal contact member from the common contact member by displacement thereof when the compact electric apparatus is mounted on the mounting base, wherein the detection circuit detects the mounting of the compact electric apparatus on the mounting base by detecting variations of electric potentials of the common contact member and the signal contact member.