Use of Light Sensors to Enable Smart Features in Energy Efficient Electronics

Use of Light Sensors to Enable Smart Features in Energy Efficient Electronics
Brightness Control for LCD Screens

Adjusting the intensity of LCD screens – based on the amount of ambient light – can conserve energy and
deliver an appropriate amount of screen brightness for users.  Energy can be saved for applications
powered from the mains, such as LCD TVs, monitors, and street lighting; and for battery powered
applications, such as smart phones, portable medical devices, video and still cameras, personal navigation
systems, portable gaming, and educational toys.

Screen brightness intensity could be adjusted based on
changes in ambient sunlight, room lighting, or other light
sources.  Such adjustments can be made automatically
through the use of ambient light sensors, which therefore serve
as natural companions to LED drivers that control screen
brightness.  Ambient light sensors that precisely match human
eye light response characteristics enable higher levels of
energy efficiency, while maintaining screen brightness levels
that are pleasing to the eye.

Features of interest when selecting ambient light sensors:
*  Photopic light response for consistent readings across different light sources
*  Dynamic dark current compensation, enabling accurate low light level measurement ranges from 0.01
lux to full sunlight
*  Linear response over the full operating range
2
*  Analog outputs to provide current or PWM outputs; digital outputs to communicate over an I C bus
*  Direct lux measurement output with 16-bit resolution for maximum accuracy

ON Semiconductor provides a variety of ambient light sensors with analog and digital outputs.  These
integrated ambient light sensors typically require no external components.

TND408-D.pdf (381.55 KB, 下载次数: 6 )