Method of measuring and quantifying the amount of sparkle in display-touch panel stacks

Presented herein is a measurement method that can be used to quantify sparkle with a value that is independent of the display under test, and that does not require any reference state. A jury appraisal was detailed, which was used to assess the level of sparkle in a display stack and grades the sparkle performance as not noticeable, noticeable but acceptable, or unacceptable. The measurement results are presented using the described method for both a 4.2-inch (131.2 dpi) display and an 8.0-inch (116.8 dpi) display with several different anti-glare films giving a range of sparkle performances. The values have been normalized to the perceived luminance to make the measured values independent of the display luminance. Using this method, it was reported that a measured value of less than 0.6 will not be noticeable, a value between 0.6 and 1.4 will be noticeable but acceptable, and any value above 1.4 will be unacceptable.