Automatic keypad backlight adjustment on a mobile handheld electronic device

摘要

A method is set forth for automatically adjusting keypad brightness on a mobile electronic device having a light sensor, a keypad and a backlight for the keypad, comprising obtaining light level samples from the light sensor, turning the backlight from off to on in the event a current light level sample is less than a threshold value below which backlight illumination becomes necessary in order to read the keypad, and from off to on after a predetermined time period in the event the current light level sample is greater than the threshold value.

主权项

1. A method for automatically adjusting keypad brightness on a mobile electronic device having a light sensor, a keypad and a backlight for the keypad, comprising:
obtaining a light level samples from the light sensor; and turning the backlight:
from off to on when a light level sample is less than a first threshold value below which backlight illumination is used, the first threshold value based on a first contrast ratio between light and dark regions of key indicia, andfrom on to off when the light level sample is greater than the first threshold value but less than a second threshold based on a second contrast ratio between the light and dark regions of key indicia, the second contrast ratio being less than the first contrast ratio the second contrast ratio based on a minimum contrast at which the key indicia is legible.