Moiré-free fingerprint sensors based on multilayer oxide-metal-oxide electrodes.

The display quality of touchscrcen devices with on-screen fingerprint sensors is reduced by moire patterns, interference phenomena caused by an overlap between the pixel pattern of the display, and the electrode pattern of the fingerprint sensor. A promising strategy for resolving this issue is to reduce the visibility of the moire pattern, by including a filling layer with a transmittance similar to that of the electrodes, between the different patterns. We propose a moire-free fingerprint sensor that uses an oxide-metal-oxide (IZO/Ag/IZO) multilayer as a highly transparent electrode. To verify the moire reduction effect, we conducted a two-dimensional spectral analysis to calculate the spatial frequencies of the superimposed image of the display and the sensor patterns, and demonstrated experimentally that the proposed electrode greatly reduces the undesirable moire phenomenon. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement