Patent ID: 7884575

Claim:
A wireless optical pointing apparatus comprising: a battery for applying a battery voltage; a light source for receiving the battery voltage to generate light; a battery voltage detector for receiving the battery voltage, detecting the battery voltage in response to a low-power signal which indicates a first power mode in which the light source is turned on to generate a first signal, and detecting the battery voltage in response to the low-power signal which indicates a second power mode in which the light source is turned off to generate a second signal; and a controller for generating the low-power signal for distinguishing the first power mode from the second power mode, and generating a detection signal for indicating a time to change/recharge the battery by comparing a value obtained using a difference between the first and second signals with a set value, wherein the set value is a digital voltage signal corresponding to a difference between a first reference battery voltage and a second reference battery voltage, the first reference battery voltage is obtained by subtracting a product of an internal resistance of the battery and a current consumed in the optical pointing apparatus during the first power mode from EMF of the battery, and the second reference battery voltage is obtained by subtracting a product of the internal resistance of the battery and a current consumed in the optical pointing apparatus during the second power mode from the EMF of the battery.