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Normal indoor shooting, the shutter open time is about 1 / 200 1 / 60 seconds,display board, so in order to capture the ideal image, the data requirements of the screen refresh rate must be above 1,000 Hz, but the driving principle and the traditional devices are difficult to accomplish this specification.
And with multiple rows of data memory and the PWM constant current driver IC function coupled with a dedicated display controller, can achieve such specifications, to achieve customer requirements, as shown in Figure 4. Loss of gray-scale outdoor LED screen appears and the gray scale display device is lost, particularly the loss of low gray scale,display boards, the impact to the display is well known, we often encounter the phenomenon of the display of gray-scale loss of two, and now were introduced as follows: (1) when the loss of non-linear gamma correction, most of such losses are reflected in the loss of low gray scale, and as long as the nonlinear correction to increase the number of bits, you can completely solve the problem
. This is not the focus of this paper; (2) LED display for outdoor photography, we often see the phenomenon of loss of gray scale display (see Figure 5), the original image source are uniform gray in transition , out into the effects of only a few elevation. In fact this phenomenon is the camera shutter open time and display the data the relationship between the refresh time.
in order to complete the transition to shoot all the gray grayscale, requiring the display of data refresh rate is far higher than the camera shutter, so that each time the shutter opening time to ensure that there are multiple data refresh. And we often have outdoor photography a shutter speed below 1ms, so the data refresh rate required to ensure that more than 3kHz to have a high-quality video results, which for a static display of outdoor screens is not difficult to achieve in terms of specifications.
Recently,Budweiser sign, the industry suddenly came direct type LED backlight technology will disappear within two years the topic! This is the 2010 Berlin Electronics Show, Panasonic executives from the assertion of a conclusion, he said, side-in LED backlight LED backlight technology such as television and on television it is widely used,light signs, the TV manufacturers are upgrading their own LED-backlit models ship ratio.
The current LED backlight technology is generally divided into direct type (Direct LED) and side-in (Edge LED), on the merits of the two technologies has been debated. Technical marketing manager for Panasonic Wagenseil, said: "We believe that direct type LED-backlit TV will not have any market, mainly because the price is too high. "Wagenseil explained:" and the side-compared to more direct type backlight LED technology and LED now face a major gap in the supply, so I do not think the direct type LED promise much.