Design of an Energy-Efficient Large LED Screen with Automatic Brightness Control Based on Ambient Light

Large LED screens consume a high amount of power, and running them at full brightness at night wastes energy and causes glare and light pollution. This paper presents the design of an energy-efficient large LED screen with automatic brightness control based on ambient light. A light sensor measures illuminance, a microcontroller maps it to a brightness level with hysteresis, and the brightness is adjusted by pulse-width modulation. Sensor calibration, brightness response and the resulting energy saving are evaluated by simulation. In simulation the automatic brightness control saved 37 % of the daily energy compared with fixed full brightness for an assumed clear-day illuminance profile, with the sensor error after one-point calibration below 3 %.