1. Field of the Invention
The invention generally relates to a liquid crystal display (LCD) panel, and more particularly, to an LCD panel having stacked protruding electrodes.
2. Description of Related Art
In the year of 1888, Friedrich Reinitzer placed cholesteric benzoate in a polarizing microscope and observed that the cholesteric benzoate in an isotropic phase and in a cholesteric phase appears to have different colors (blue violet and blue), and the color change in the cholesteric benzoate occurs within a rather small temperature range (approximately 1° C.) between the isotropic phase and the cholesteric phase. In 1970, by conducting the volume analysis and applying a high-resolution differential scanning calorimeter (DSC), various scientists proved that said phenomenon is a thermodynamically stable phase and is referred to as “blue-phase”.
The “phases” within the blue phase are referred to as BP I, BP II, and BP III (in increasing order of temperature), and BP III mentioned in the literature on the subject refers to a “fog phase”. In comparison with the cubic structure of BP I and BP II, the structure of BP III is amorphous. The structure of BP III under the polarizing microscope appears to be unclear (i.e., BP III seems to have no specific structure) and can be barely observed with use of the polarizing microscope.
The basic unit of the structure of BP I and BP II has been confirmed to be shaped as double twist cylinders (DTC), and the orientation of the DTC ensures the lowest free energy. Besides, the double twist cylinders are perpendicular to each other. This orientation results in lattice defects and is deemed as a pre-transitional phenomenon from a liquid crystal phase to the cholesteric phase. Hence, blue phases are categorized as frustrated phases. Based on Bragg reflection, Kossel diffraction patterns, optical structures, crystal growth, and other experimental researches, it is found that BP II has a simple cubic (SC) structure (Mol. Cryst. Liq. Cryst., Vol. 465, pp. 283-288, 2007), and BP I has a body-centered cubic (BCC) structure. Different from other liquid crystal phases (e.g., nematic phases, smectic phases, and isotropic phases), BP I and BP II frequently exhibit color patterns (J.A.C.S, 2008, 130, 6326, Kikuchi et. al.) with the platelet texture when observed under the polarizing microscope. This is because the lattice period gives rise to the Bragg reflection within the wavelength range of visible light.
Normal liquid crystal phases are optically anisotropic, while the blue phases are optical isotropic. That is to say, the blue phases have low or zero birefringence.
The lattice periods of the blue phases are functions of the wavelength of visible light, thus resulting in the selective Bragg reflection. Accordingly, the blue-phase liquid crystal can be applied to fast light modulators. However, in spite of theoretically prediction or experimental observation, it is found that the blue-phase liquid crystal merely exists in the molecular material with high purity and high chirality, and therefore the blue-phase liquid crystal exists within a small temperature range (less than 2° C.). This is the reason why the blue-phase liquid crystal is often discussed in the academia rather than in real field of applications.
In the last decade, the blue phases characterized by fast response speed draw the attention of the academia and the industry for the purpose of improving the display quality of LCD panels to surpass the display quality of cathode ray tube (CRT) displays. In consideration of actual applications, the blue-phase liquid crystal needs to be applied within a wide temperature range, and thus various technical developments in this regard have been proposed. For instance, the blue-phase liquid crystal that can exist within a wide range of temperature is generated due to stability of polymers (i.e., formation of polymer meshed structure) (Nature materials, 2002, 1, 64). Additionally, in 2002, Kikuchi et al. placed a small amount of monomers and photoresist into the blue-phase liquid crystal which was then irradiated by light within the blue-phase temperature range, and thereby the stable blue-phase liquid crystal that has a gel-like structure and can exist within a temperature range of approximately 60° C. is successfully generated.
Although the blue-phase liquid crystal is characterized by fast response speed and optical isotropy, the operating voltage of the blue-phase liquid crystal is relatively high and can reach up to 55 V. In terms of mass production, the high operating voltage of the blue-phase liquid crystal is one of the issues to be resolved.