How do I improve the contrast on a segment display?


Apr 05, 2016

This is the second in a series of three blogs exploring advances in segment display technology and showing how it remains a real alternative to TFT displays. Previously we explored adding colour to segment and dot matrix displays.

What is the viewing angle like on a segment display?

The typical viewing angle and contrast of today’s segment displays are generally better than those of earlier generations, giving sharper definition and clearer legibility whether viewing from a distance or close-up. New vertical-alignment technology enables segment displays with a conventional black background to deliver still more impressive visual performance, by preventing bleed of even small quantities of light from the lit segment into the dark background. The improvements are particularly noticeable with displays operating in negative mode, and results in crisp, sharp segment edges that give a beautiful, high-quality effect.

improving contrast on segment displays

This is achieved by making the liquid crystals naturally align vertically to the glass substrates. When no voltage is applied, the liquid crystals remain perpendicular to the substrate, greatly reducing light bleed-though between crossed polarisers as observed in TN displays. When voltage is applied, the liquid crystals shift to a tilted position, allowing light to pass through and create a grey-scale display depending on the amount of tilt generated by the electric field.

Traditionally, the way to achieve this kind of improvement in performance has been to use a relatively expensive technology such as DSTN (Double Super Twisted Nematic). Vertical alignment now makes the effect more affordable and more effective, and has a deeper-black background, a higher contrast ratio, a wider viewing angle, and better image quality at extreme temperature.

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