A Study of LC Devices with Periodical Structures
Date Issued
2014
Date
2014
Author(s)
Chen, Jyun-Yu
Abstract
Monitor technology has been a popular topic over the recent years, from the earlier CRT stages to the gradually common liquid crystal display (LCD), which has been also expanding in size; manpower and resources have been invested in all of the mentioned technology. In the past few years, portable mobile devices are introduced to the world in large numbers, ranging from smartphones to smartwatches. People’s lives are about to merge with technology products, and monitors are definitely an essential element. Portable devices are usually used in environments with strong ambient light, the light will cause most of the Transmissive LCD to show a washed out effect; the said effect resulted in the production of the Reflective LCD. Although the Reflective LCD is not easily affected by ambient light, problems such as an insufficient contrast ratio or weak brightness occurs often, because the light source of Reflective LCD comes mainly from ambient light. When the device is indoors, the weak ambient light causes the light source to decrease largely for Reflective LCD. Technology researchers then combined the strengths of the two LCD’s and invented the Transflective LCD, which not only possesses the back light module of the Transmissive LCD, but is also able to display images of good quality outdoors and save power like the Reflective LCD. But the Transflective LCD is more difficult to produce than the two other LCD’s, and is divided into two types according to the structures: Single Cell Gap Transflective LCD and Double Cell Gap Transflective LCD. Double Cell Gap Transflective LCD enables the electro-optic curves in the transmissive region and reflective region to match through different cell gaps, but it is complicated to fabricate and will cost more to produce. The Single Cell Gap Transflective LCD is easier to produce, but because the cell gaps are the same, it is more difficult to match the electro-optic curves with each other. This thesis allows the electro-optic curves in the reflective region to gradually adapt and match the transmissive region via the periodical electrode structure, also to achieve a pre-tilt angle by applying voltage to the curing process of the Polymer Stabilized Liquid Crystal (PSLC), this allows the adjustment of the electro-optic curves and is a much simpler and convenient way compared to others. We also discuss another periodical LC device called Holographic Polymer Dispersed Liquid Crystal (HPDLC). We use two-beam interference lithography to fabricate HPDLC; Also, HPDLC can be used to record holography image. Otherwise, we can apply electric field to change the alignment of LC. That is to say the effective refraction index can be changed. This device can be used in Holography, focus-tunable microlens, and wavelength division multiplexing etc. The last chapter discusses the PDLC produced by high concentration polymer monomer, and how Fabry-Perot Cavity is produced by the latter. We want to take advantage of the high transmission, adjustable reflection and the high-speed reaction to change the transmission of specific wavelengths by applying different voltage within the resonator. This will be used to complement the shortcomings and serve as an excellent optical shutter.
Subjects
Transflective display
periodical electrode
Fabry-Perot cavity
polymer stabilized liquid crystal (PSLC)
polymer dispersed liquid crystal (PDLC)
liquid crystal
optical shutter, curing voltage
Type
thesis
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