Patent ID: 7042434

Claim:
A method of driving a lamp for an LCD of a portable computer, comprising: setting a default brightness in the LCD that corresponds to a prescribed value stored in the portable computer; checking a surrounding temperature of the LCD; selecting one of a first mode and a second mode for operating the lamp, wherein operating the lamp is the first mode comprises, receiving a user selected one of plurality of brightness control levels to set a first brightness and determining a corresponding first drive current as a drive current for the lamp, maintaining the first brightness within a first temperature range while the drive current varies to reduce lamp power consumption, determining a corresponding drive current at a minimum temperature of the first temperature range as a second drive current for a second temperature range that is below the first temperature range, and maintaining the second drive current while the temperature of the lamp is within the second temperature range to reduce the lamp power consumption, and wherein the operating the lamp in the second mode comprises, determining a third drive current that corresponds to the default brightness, maintaining the third drive current within a third temperature range while the brightness changes, determining a corresponding brightness level at a minimum temperature of the third temperature range to set a fourth brightness for a fourth temperature range that is below the third temperature range, and maintaining the fourth brightness while the temperature of the lamp is within the fourth temperature range while the drive current changes.