LED背光源整合系統設計之色溫管理

Abstract

整體系統主要是LED的色溫管理，方法由微控制器產生PWM控制LED的驅動電路使LED發各種顏色的可見光，於LED在長時間使用下會隨溫度的變化而影響色溫與亮度的穩定性，所以配合顏色感測模組做光電轉換的類比轉數位的讀取以做為光回授的控制，另一功能溫度顯示以溫度感測元件讀取LED背光板溫度作一監控。整合系統包括軟體發展環境規劃、硬體設計規劃與整體功能驗證事項。軟體部分微控制器採用Motorola之16位元MC9S12控制晶片，嵌入式即時作業系統設計描述如下，包括記憶體管理、周邊資源管理，應用程式介面(API)規劃。硬體部分包括LED陣列模組、LED(RGB)驅動模組、顏色感測模組與溫度感測模組選用，其電路設計有電氣考量與整體實際的Layout製作。在整體功能驗證方面，本文規劃了MC9S12 EVM PWM 0~100%DUTY訊號輸出、顏色感測之光電轉換值輸入、溫度感測準確性皆由訊號檢測器讀取各單一驗證，最後LED背光板亮度與溫度做光回授補償的驗證。

This study aims to verify the function of the integration system designed by the combination of the software and hardware development. The software design includes Micro-controller (Motorola 16 bit MC9S12 control chip) and Embedded Real Time Operation System (memory management, peripheral management and application program interface). The hardware design involves LED array module and LED (RGB) driver module, in which the electrical design concerns its specifications and an integrated layout is designed. The function of the system derived from the PWM signals was produced by MCU to control the driver circuit of the LED and produced visible light with different colors. The stability of chromaticity and brightness of the LED can be affected by its long-term use. Therefore, the Optical Feedback (OFB) is controlled by conducting optical-to-electric change and by reading the analog-to-digital signals. In addition, the thermal monitor is read through the temperature sensor on the LED backlight. In conclusion, Ultimately the 0~100% DUTY signal output of the MC9S12 EVM PWM, the optical-to-electric change output and the accuracy of backlight temperature are all verified correct. Finally the brightness and temperature of the LED backlight also gained the accuracy of the optical feedback.