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EETE DECEMBER 2012

straight visibility line on a log-log plot. Figure 6 shows how vari- ous film configurations may be studied to determine the best solution to stay above the visibility line. This solution can then be used for a cost-driven optimized system. The conflict between the aesthetics of a dead-front curved touch lens, display visibility need, and the functional aspects of the display interface create a dynamic new area of development for the automotive supplier. To be productive in this space will require the ability to assess optical performance and develop the best system solution. Fig. 5: Small signal reflection measurement method. It is not uncommon to calculate very high required display luminances on the order of 3000cd/m2 out of the TFT for dead-front touch-lens systems. This value is much larger than typical automotive TFT luminances of 500-850cd/m2 that do not have a “dead front” neutral density lens in front of the TFT. The luminance reduction of the display at center stack view- ing angles also needs to be considered for different backlight brightness enhancement film configurations. By considering thermal maintenance from a system level, high luminance 3000 cd/m2 displays can be achieved, which dissipate approximately 20 Watts of backlight power for an 8” TFT. Predictive display visibility analysis Once the total reflected background luminance is determined, the required display luminance can be estimated using histori- Fig. 6: Display luminance determination cal human factor studies. The required display luminance is a When 4 channels are not enough… A unique 8 channel Mixed Signal Oscilloscope which provides comprehensive measurement and analysis capabilities for embedded, automotive, power and mechatronics applications NEW NEW DLM4000 Series 8 analogue channels Up to 24 digital inputs Up to 500 MHz bandwidth Up to 125M points long memory Solve your complex measurement requirements faster and easier than ever before Watch the video at: http://bit.ly/T1gLUn and contact us to see how the DLM4000 can help you. YOKOGAWA EUROPE B.V. Tel.: + 3188 464 1429 tmi@nl.yokogawa.com http://tmi.yokogawa.com www.electronics-eetimes.com Electronic Engineering Times Europe December 2012 19


EETE DECEMBER 2012
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