Chapter 6 Conclusion and Future Work
6.2 Future work
The adaptive backlight can be viewed as a natural extension of the consistent color in the sense that the fourth field is modified instead of only white, yellow, or cyan. The adaptive field allows for a higher focusing of image energy in time, while reducing the visual saliency of individual fields. So far, the adaptive color has only been tested in combination with global LED backlights that allow fields to change color only as a whole backlight. Although this global adaptation was verified to satisfactorily reduce CBU, we anticipate that the performance will greatly improve when combined with a local color dimming LED backlight to enable a far superior
adaptation to the incoming video content. Fig. 6-1 shows the original image and individual color fields of global and local adaptive backlights. The two characters are presented by themselves color adaptation as shown in Fig. 6-1(c). Simulated results of non-adaptation (conventional RGB), global and local adaptation methods support the prediction of CBU reduction, as illustrated in Fig. 6-2. Furthermore, three or even two local color dimming fields can be applied for a slower response time with typical LCs instead of fast response ones. The algorithm for the cases of fewer color fields can be expectably reported on a normal twisted nematic (TN) mode LCD in the near future.
In the scope of whole LCD system, we have discussed and concluded that the major consuming devices in LCD embodiment are polarizers and color filters. In this thesis, the sequential driving as a feasible approach provides to leave out the color filters. Nevertheless, the polarizer still absorbs about 50% incident light, thus much lower the output light efficiency. Therefore, liquid crystal capable of having spontaneous polarization can be used for excluding the polarizer in LCD embodiment.
Liquid crystalline conjugated polymers are potential candidates as inexpensive, easy to process polarized back lights for liquid crystal displays [100]. The device efficiency and brightness can be modified by the property of alignment layer. This polarized liquid crystal shall be an appealing topic to explore in the future.
In addition to enhancing the optical efficiency of components, the power consumption of light source is anticipated as low as possible. The highly efficient white LED can be introduced into the backlight besides RGB LEDs as shown in Fig.
6-3. The white LED is proposed to contribute major intensity in the color-mixed field.
The efficiency of RGB mixing white of 40 lm/W is markedly lower than that of single white LED of 100 lm/W [101]. Consequently, the combination of white and RGB LEDs is viewed as a further reduction of power consumption.
Fig. 6-1 The (a) original image and individual color fields of (b)global and (c)local adaptive backlights.
(a) non-adaptation (b) global adaptation (c) local adaptation (a) non-adaptation (b) global adaptation (c) local adaptation
Fig. 6-2 The CBU images with (a) non-, (b) global, and (c) local adaptation.
Fig. 6-3 The schematic of added white LEDs into the backlight module.
In a world that is increasingly aware of its ecological footprint and energy issue, the sequential driving technology has wide-spread acceptance to upgrade the efficiency of LCD applications. As the power-saving, or called green, technique become a common view of human beings, the sequential driving prototypes have been widely demonstrated and greatly capable of regard for both image quality and power consumption. The newly developed algorithms mitigate the effects of color breakup, and allow sequential driving LCDs to be attractive in practical scopes covering research for mobile devices, signage, monitor, and TV. Therefore, consumers can benefit from appealing multi-media; meanwhile, lower the injury that is causing to our planet.
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Appendex A
Implementation of FPGA
We choose XC3S2000 in Xilinx’s Spartan-3 series as our platform because the gate count and I/O number in S2000 meet our requirement. The framework of FPGA controlled circuit is shown in Fig. A-1. This circuit includes clock generation, input buffer, image process, and timing controller modules. The functions of these modules will be described as follows.
Fig. A-1 The framework of controlled circuit.