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The operation of the digital camera system of a camera cellular phone consists of the following steps. First, the image is captured by the image sensor. Then the digital signal processor is used to compress and resize the image. Finally, the compressed data is stored into RAM and output to the display for the user to preview. Currently, most of the main output display screens of the camera cellular phones on the market are TFT-LCD’s. Compared with CSTN-LCD’s, this kind of display provides a better contrast ratio, color gamut, view angle, and response time. If this kind of display is adopted, better display effects will be obtained. However, it also costs more on the mold and the production. In this thesis, a display module is designed for the camera cellular phone which uses a passive CSTN_LCD. The goal of this research is to improve its contract ratio, color gamut, view angle, and response time during the production process of the module so that a better display effect can be obtained and the cost of production can be decreased. The hardware circuit in our display module for the camera cellular phone includes a digital sensor module, a digital signal processor, a passive CSTN_LCD driver IC, and other supporting circuits. In the experiment, the TI MSP430F149 single chip microcomputer with its 16-bit RISC assembly is adopted to test the display module. It is shown that the requirements of the optical and electrical characteristics on the preview, capture, compression, and display of the images can be satisfied in our design.
Keywords: Image Capture System, Image Sensor, TFT-LCD, CSTN-LCD
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