This thesis proposes a dimming approach with Double Pulse Width Modulation for equalizing the light output of the back light with light emitted diodes (LEDs) for large scale outdoor liquid crystal displays (LCDs). The approach compensates the difference among the LED light bars by adjusting the power outputs of converters according to the feedback of light strength from light sensors. With the proposed Double Pulse Width Modulation method, local brightness adjustment on the light bars can be made to provide a uniform light output and the dimming function for LCD can be retained. Experiments results made on a 46¡¨ LCD with four LED light bars demonstrate that the double pulse-width- modulation can provide uniformly in the light bar output. The experimental results show the proposed Double Pulse Width Modulation (DPWM) method can alleviate the problem from divergence of the light bars and thus can generate more uniform light output on LCDs.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0825111-130535 |
| Date | 25 August 2011 |
| Creators | Huang, Chao-Hsuan |
| Contributors | Chin-Sien Moo, Chih-Chiang Hua, Yao-Ching Hsieh, Ching-Ran Lee, Jia-You Lee |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0825111-130535 |
| Rights | unrestricted, Copyright information available at source archive |
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