Taking the visibility mathematical function into account, various optical configurations may be examined to ascertain the required display luminances. Figure 6 shows that lower display luminances (higher optical system efficiencies) can be achieved with different optical other than the traditional neutral density filter (ND). However, the background reflection level must be considered to pick the best optical configuration based on actual in-vehicle jury evaluations.
Minimizing Fingerprint and Reflections:
Another consideration for front lens aesthetics is the use of antiglare (AG) films to lessen the effect of fingerprints and reduce the clarity of specular reflections. AG films must be used with caution due to unwanted speckle and decreasing the sharpness of the TFT image (Figure 7) as the film is moves further from the TFT.
Figure 7: AG Film Blurring the TFT Image
The blurring performance of AG films may be quantitatively determined by obtaining the line-spread-function and associated modulation transfer function via FFT techniques .
Performance & Conformance
One of the challenges is to ensure vehicle center display visibility under all lighting conditions. Visibility problems occur when engineering principles coupled with human factor studies are not properly applied. The fundamental geometric requirement is that the display must be positioned and tilted so no window can be seen in a mirror placed on the display surface. If a window can be seen, a potentially unsafe specular sunlight condition could result in increased driver recovery time and possible retinal damage from seeing the sun's reflection. No