Acer DX900 User Guide - Page 105

Light Sensor The unique light sensor within your Pocket PC enhances the accuracy of onscreen view and decreases your eyestrain while saving on more battery life. Based on the ambient light intensity the sensor detected, it will adjust backlight brightness dynamically. The lighter the environment is, the more illumination the device outputs to brighten the screen; in a dusky place like a tunnel, the device dims the screen a bit to reduce power consumption. Tap > Settings > System tab > Backlight > Backlight Level tab. Check "Auto-adjust backlight by light sensor" to activate the light sensor. Tap to set your own backlight profiles. Drag the slider under each of the three light conditions to set your own profile. Tap OK to save your settings. Tap to restore default settings. Customize Your Pocket PC 5-5