Flexible Bistable Cholesteric Liquid Crystal Display Unit

With the continuous development and improvement, the liquid crystal display has already become the most important information display technology. LCD can be seen everywhere, from mobile phones, personal digital assistant to big-screen televisions. But LCD has not made fully use of liquid crystal's advantages of portable and low power consumption. Nowadays, the research of information display technology is focus on two aspects, one of which is light, low power consumption, the other is flexible display.Because of special structure of the molecular alignment of cholesteric liquid crystal, it has unique optical properties, such as optical waveguide effect, Bragg reflection and optical rotation effect. Bistable cholesteric liquid crystal reflective displays can be made by polymer stabilized cholesteric liquid crystal or surface stabilized cholesteric liquid crystal. This mode of display can retain image in the power off situation. Not only is it low power consumption, high brightness reflective, high contrast, but also can be manufactured flexible displays by using flexible plastic films. This kind of displays can achieve large capacity of display without active matrix, so it is inexpensive to product.As traditional bistable ChLCD, its disadvantage is that it reflects certain wavelength light with narrow bandwidth based on principle of Bragg reflection, so these displays can't achieve black-and-white display. In order to broaden the Bragg reflection spectra, it needs to introduce polymer network into cholesteric liquid crystal. This dissertation studied display characteristics of polymer stabilized bistable cholesteric liquid crystal display cells as the focus. First of all, the dissertation studied electro-optical property of polymer network liquid crystal and fabrication process of flexible display cell. Then basing on work above, the dissertation studied reflective property of polymer stabilized cholesteric liquid crystal and flexible display cells were fabricated using flexible plastic film.In PNLC research, the threshold voltage and the saturation voltage reduced compared with traditional PNLC by introducing mixed monomer of polymer with low anchoring power. The dissertation studied electro-optical property and network structure of PNLC in different fraction of liquid crystal and monomer of polymer situation. The research showed that the threshold voltage and the saturation voltage reduced along with the ratio decreasing between ethylene glycol dimethacrylate and amyl methacrylate in the case of steady fraction of mixed monomer of polymer and liquid crystal, and viewing angle also increased, but contrast reduced.The dissertation studied fabrication process of flexible display cell, and mainly studied flexible cell thickness controlled process and process of filling cell with liquid crystal.On the basis of work above, the dissertation studied reflective property of polymer stabilized cholesteric liquid crystal, and chiefly studied the influence of the concentration of monomer of polymer to reflective property of display cell, and the influence of adding another monomer polymer to reflective property. It can broaden the reflection spectra of display cell to introduce ethylene glycol dimethacrylate into cholesteric liquid crystal. The reflection spectra of display cell widened along with the concentration of ethylene glycol dimethacrylate increasing, but the saturation voltage increased and contrast reduced. The saturation voltage of display cell can be reduced by adding amyl methacrylate, but the reflection spectra also reduced.On the basis of fabricating flexible PNLC, flexible bistable cholesteric liquid crystal display cell has been fabricated using flexible film. The dissertation studied fabrication process of flexible bistable cholesteric liquid crystal display cell.