Patent ID: 8884866

Claim:
A backlight brightness control method for adjusting a backlight brightness for a display of an electronic apparatus, wherein the method comprises: (a) detecting an ambient brightness of the electronic apparatus to output an ambient brightness signal; (b) determining whether to adjust the backlight brightness for the display according to a comparison between a target brightness and a current backlight brightness of the display; (c) selecting an adjustment value if the result of the comparison in step (b) is that the backlight brightness should be adjusted, wherein the adjustment value is selected from a plurality of step sizes in order to decrease the backlight brightness gradually if the comparison result of step (b) indicates that the difference between the current backlight brightness and the ambient brightness is at least as large as a decrement threshold, so that the backlight brightness is reduced gradually towards a target backlight brightness, a first step size being selected as the adjustment value if the current backlight brightness is at least as large as a signal threshold and a second step size being thereafter selected as the adjustment value when the current backlight brightness level is smaller than the signal threshold, the absolute values of the first step size and the second step size being different, and wherein the adjustment value is selected according to a difference between the target backlight brightness and the current backlight brightness if the comparison result of step (b) indicates that the ambient backlight brightness has risen above an increment threshold, and (d) adjusting the backlight brightness of the display according to the current backlight brightness and the adjustment value, wherein the first step size is used to decrease the pulse width of a PWM drive signal for a backlight of the display one or more times until the current backlight brightness is smaller than a signal threshold and the second step size is used to decrease the pulse width of the PWM drive signal one or more times until the current backlight brightness becomes smaller than the decrement threshold.