Electronic devices with touch screen and optical wave plate assembly thereof

A user input system, comprising:

• an optical wave plate assembly, comprising a phase wave plate and a phase retardation layer, wherein the phase retardation layer is disposed on at least one surface of the phase wave plate, the phase retardation layer comprises a code pattern, the code pattern comprises encoded information and coordinate information, the optical wave plate assembly converts an incident light into at least one of a first polarized light having a first polarization state and a second polarized light having a second polarization state through the phase retardation layer, wherein the first polarization state and the second polarization state are different;
• and
• a reading device, for acting on the optical wave plate assembly, sensing presence or absence of the first polarized light having the first polarization state, analyzing a distribution of a change in brightness of the code pattern, and performing a decoding to obtain the encoded information and coordinate information.