TECH ARTICLE
Figure 1: Pixel settling time after writing data The secret to all of this lies in the timing of the illumination, delivering the light to the screen at precisely the right time, in synchronism with the displayed image and allowing for the characteristics of the LCD itself and any losses in the optical components. The solution is broadly referred to as a ‘scrolling backlight system’ but employs a number of techniques to realize a superior picture all of which are made possible by sophisticated LED driver technology, such as that embodied in Atmel’s MSL2164 series devices. This article will reveal how this works in principle with the help of some timing diagrams and a description of the different modes of operation. Let’s start with a commonly used method for overcoming one of the fundamental issues with LCDs; namely the slow response time of the liquid crystal material, which gives rise to the problem of motion blur where on-screen movement is faster than the time it takes for the pixel to settle to a new value. This can be greatly improved by blinking or interrupting the backlight during the period while the pixel is changing. Commonly referred to as ‘black
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