Recently, many kinds of peeping prevention technologies for LCDs have been proposed. Most of them can be categorized into two groups, the methods attaching additional LCDs and the special LCD structures. We propose a new kind of peeping prevention technology in which new optical films are used instead of polarizers for conventional LCDs. The optical film possesses the HAN (Hybrid Aligned Nematic) LC structure containing dichroic dye. The incident light parallel to the molecular axis of the dichroic dye is not polarized. So, the light strength cannot be controlled by the LCDs. This method can be applied to all kinds of conventional LCDs.