No abstract

In this paper, we present experimental results obtained for a device incorporating a nano-PDLC inside a Fabry-Perot cavity. Our aim is to produce a fast-response and polarization-independent light shutter with potential applications in e.g. telecommunication systems since nano-PDLC is known for its fast response time. In our chosen example of nano-PDLC with 70 wt% polymer and 30 wt% liquid crystal (E7), we obtained a light shutter with contrast ratio = ∼7.5 under an applied voltage of ∼50 V. Response time is ∼2 to 3ms and transmission is ∼20%. All these device performances, such as operation voltage, transmission and response time can be improved in future by improving the cavity performance and using a faster liquid crystal material. Moreover, comparison in performance is also made for devices with different concentrations of polymer and liquid crystals. Discussion on the residual scattering effect of the nano-PDLC inside the Fabry-Perot cavity is also included. It is interesting to observe that the undesirable effect of the residual scattering of nano-PDLC at low voltages may actually help improve the contrast ratio and/or lower the operation voltage of the device.

A heads-up display (HUD) commonly uses liquid crystal technology to generate images. However, the intensity of the light decreases significantly due to passing through polarizers. Therefore, a polarizer-free display is a superior approach to utilize light more efficiently. We demonstrate the feasibility of using polymer dispersed liquid crystal (PDLC), which consists of polymer and liquid crystal, as an optical shutter to fabricate a simple see-through projected display device. The unique electro-optical characteristics of PDLC make it suitable to define the projected image shape. In our device, we used a 36 watts collimated light emitting diode as a backlight source so that the projected image can also be seen clearly under daylight. Since PDLC does not require/utilize polarizers, it achieved high light efficiency 70% . In this paper, we showed promising results of projected images with various colors (red, green, and blue) that can be applied to see-through projected displays. From our experimental results, the see-through projected display device by PDLC can achieve a contrast ratio of 1000:1 and the response time is approximately 15 ms. The driving voltage is less than 25 V and brightness is over 3000 nit.Index Terms-Heads-up display (HUD), polymer dispersed liquid crystal (PDLC).