Q: Why does a 3CCD camera have 800 TV line resolution?

A:  Due to the transferred speed limitation of a CCD ,when the maximum pixels transferred on 30 frames per second will be no more than 480k pixel or 800X600. Therefore, the maximum of horizontal resolution is limited to 480 TV lines. To break through this barrier, we use 3 CCD device and shift the position of half pixel to have the same outcome as 1600X1200 pixel, 1.92 mega pixels and  maintain a good frame output of 30 frames per second ( or 60 fields per second ). 

Legacy Single CCD Sensor	3 CCD   Sensor

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Digital camera sensors with 2 to 4 mega pixel are useless for CCTV cameras and the camcorder industry because they usually have very low sensitivity ( 5 to 30 lux ) and very slow frame rate ( 3 to 5 frames /sec. ). Therefore, 3 CCD technology is the only known way to make high end, high resolution and high sensitivity CCD cameras.

A prism is split white light into red green and blue, and each light is then diffracted to the respected CCD sensor. The three of the B/W high sensitivity sensors then create a color image by calculating the vector of out put of each CCD sensor.