Patent ID: 7535196

Claim:
A power apparatus comprising: a first battery disposed in a main body of an electronic equipment; a battery unit detachably connected to said main body; a second battery disposed in said battery unit; first detecting means for detecting, before a power supply of said electronic equipment turns off, a detaching-state prior to complete detachment of said battery unit from said main body; and control means for switch-controlling, when said first detecting means detects said detaching-state in said battery unit and said main body, the power supply of said electronic equipment from said second battery to said first battery, said first detecting means comprising: a light emitter disposed on a side of said battery unit that faces said main body when said battery unit is connected to said main body; and a light receiving element disposed on a side of said main body that faces said battery unit when said main body is connected to said battery unit, wherein, said detaching-state is detected when light output from said light emitter that was previously received by said light receiving element is no longer being received by said light receiving unit.