The Study Of Key Technologies Of 2D/3D Switchable Display Based On LC Lens

As the development of the science and technology, people are having more and more requirements on display technologies. People are expecting the display can be virtual reality and can give people 3D experience. After study of many years, 3D display technologies have made many progresses. Nowadays there are two main 3D display technologies: Stereoscopic 3D display and autostereoscopic 3D display. The 3D performance of the stereoscopic 3D display is better, but it requires people to wear additional equipments such as 3D glasses, helmets and so on, so it is used for a few places such as cinema. Autostereoscopic 3D display can give people 3D experience without additional equipments, so it is the main study direction of the 3D display. The 3D performance of autostereoscopic 3D display is worse than the stereoscopic 3D display. So how to develop the 3D performance of the autostereoscpic is the main research subject.Of the autostereoscopic 3D display technologies, the LC lens type can easily realize 2D/3D switchable through the voltage off or on. Except this, it shows many advantages such as simple structure, easy process and flexible driving. Several factors affect the optical characterization of LC lens for 2D/3D switchable display, such as electric field and alignment direction of the LC layer. If the alignment direction of the LC is parallel to the electrodes, there exists horizontal electric field due to the voltage difference between the joint electrodes, making LC molecules rotate in both vertical and horizontal directions. This causes the coexistence of ordinary and extraordinary lights, which degrades the LC lens effect. If the alignment direction is vertical to the bottom electrodes, the coexistence of ordinary and extraordinary lights disappears, but leads to LC texture defect that appears at the joint area between lenses. Another factor is electric field, which can be reflected by the cell gap. If we use large cell gap LC lens, we can reduce the voltage difference between the joint electrodes. However the large cell gap causes other problems such as slow response time, difficult fabrication process and high costs.The 2D/3D switchable display based on LC lens have some disadvantages. Many factors determine the focal length of the lens, including the radius, the birefringence, the cell gap, the pitch of the LC lens and the voltage distribution of the control electrodes. Since the pitch of the multi-view LC lens for large size display is very large and the birefringence of the LC is relatively small and the maximum birefringence of LC is of less than 0.5, the LC lens thus needs a very large cell gap to obtain an appropriate focal length. The large cell gap can produce other problems such as slow switching speed, difficulty in fabrication and high cost. In order to solve the issues, we propose a Fresnel-type LC lens to achieve the same lens effect with a small cell gap and fast 2D/3D switching speed. To get an ideal Fresnel lens profile, we give two ways: the first one is to laminate a polymer wall between the joint electrodes of different sub-lenses. The polymer wall cuts down the horizontal electric field. Another way is reducing the spacing between the electrodes. We use the multilayer electrode structure which can be equivalent to reduce the spacing. Because of the fast response speed, the blue phase LC is used to replace LC in LC lens. But the traditional way is to use the vertical electric field to induce the phase shift of the blue phase LC which can only use the one third of the birefringence of the blue phase LC. We use the horizontal electric field to induce the phase shift which can almost produce the birefringence of the blue phase LC. And then to get a better 3D performance we raise some other structures.