Patent ID: 6859196

Claim:
An input device comprising: a housing; electronic circuitry for detecting user inputs and transmitting signals corresponding to said inputs to an electronic device; a sleep-mode circuit, coupled to said electronic circuitry, for activating a reduced power operation of said electronic circuitry; a capacitive hand detection circuit for detecting the proximity of a user's hand to said housing and producing a hand detect signal; and said sleep mode circuit being responsive to said hand detect signal to awaken said electronic circuitry from said reduced power operation; wherein said hand detection circuit is mounted inside a ton of said housing, such that a portion of said housing insulates said user's band from said capacitive hand detection circuit; wherein said capacitive detection circuit comprises first and second electrodes on said housing for capacitive connection with a user's hand; a first circuit, coupled to said first electrode, for determining an amount of time for charging of a capacitance connected to said first circuit; and a second circuit, coupled to said second electrode, for determining an amount of time for discharging of a capacitance connected to said second circuit; such that an internal virtual ground is produced between said first and second electrodes; and wherein said first circuit comprises; a comparator; a controller coupled to an output of said comparator; a voltage divider feedback circuit coupled between an output and a reference voltage input of said comparator; a detection capacitor coupled between said first electrode and a signal input of said comparator; and a switching circuit selectively coupling said signal input of said comparator to high and low voltage supplies.