Batteryless display apparatus

摘要

A display apparatus comprises a cholesteric liquid crystal display device comprising a layer of cholesteric liquid crystal material interposed between electrode layers and a piezolelectric element electrically connected to the electrode layers of the cholesteric liquid crystal display device. The piezolelectric element is capable of being manually activated to generate a drive signal which is sufficient to switch the layer of cholesteric liquid crystal material from the planar state to the focal conic state. The layer of cholesteric liquid crystal material is capable of being sheared to switch the cholesteric liquid crystal display device from the focal conic state to the planar state by manual compression of the cholesteric liquid crystal display device, or by a further piezoelectric element. Thus the display device can be switched without the need for a battery or other power source.