本論文主要是運用CPLD (Complex Programmable Logic Device)設計一模糊控制器,來達到自動調控系統的顯示器背光亮度，使系統可在不同的環境照度下，提供適當的背光源，如此可達到節能省電，並可提升系統的電池使用長效性，並且讓使用者得到最佳的視覺感受。我們所研製的系統透過光電二極體，可以隨時偵測系統使用環境的照度變化情形。經由模糊控制晶片上的模糊化電路、規則庫電路、推論引擎電路以及解模糊化電路等主要電路模組執行模糊運算，並產生所需的脈波寬度調變(Pulse Width Modulation,PWM)訊號來調整背光亮度，以使系統在不同的環境照度下，提供最適當的發光二極體(Light Emitting Diode,LED)背光源。 本文與現存類似系統最大不同，是我們運用模糊控制可達到更多區段且線性、連續式的穩定自動控制，且能藉由程式的修改，輕易的達成更有彈性的設計與運用，而這也是使用傳統硬體控制方法所不足的地方。 This thesis, based on the use of complex programmable logic device (CPLD), mainly concerns with the design and implementation of a fuzzy logic controller (FLC) so as to automatically adjust the backlight brightness of a display-system.It provides sufficient backlight brightness under different environment,saves energy, extends the lifetime of batteries and makes the user comfortable. The proposed system detects the environmental illuminance by a photodiode. After A/D conversion, the signal is injected into the FLC chip which consists of the fuzzifier circuit, rule based circuit, inference engine circuit,and defuzzifier circuit.In response to the variation of environmental illuminance, the FLC carries out the designated fuzzy operations. This in turn produces an appropriate pulse width modulation (PWM) signal for adjusting the light emitting diode (LED) backlight brightness. The major difference between the system proposed in this thesis and the similar ones is the use of fuzzy control, which makes the change of illuminance automatic and smooth. All of these can be done via the proposed FLC,which will not be achieved by traditional hardware control.
