A method to hide private information (PI) in private information protection liquid crystal displays (PIPLCDs) using periodical waveplates and pixel quaternity is reported in this study. The PIPLCD structure and its operation mechanism are conceptually elucidated. Users employing wide-view broadband circular polarizers (WVBCPs) can see PI hidden in images displayed on the PIPLCDs in PIP mode. However, people who do not use WVBCPs can only see the displayed images but not the PI at almost any viewing angles. The issues of the PIPLCD in PIP mode and possible fabrications of the periodical waveplates are also discussed.