研究者詳細 - 山口　留美子

<p>A reverse mode liquid crystal (LC) characteristic which shows a transparent voltage off-state and a light scattering on-state can be obtained by two light scattering mechanisms. One is using an index mismatching between LC and polymer matrix and another is using a micro-lens array with a short focal length. Here, we combine two reverse mode technologies in one LC cell. We investigate relations between the cell thickness and the lens diameter of a hole array patterned electrode and successfully obtained the stronger light scattering with low driving voltage. Not only an extraordinary ray but an ordinary ray can also be scattered by non-uniform electric field which is caused by using hole pattered electrodes on both side of the substrates.</p>

DOI

Thresholdless electro-optical property in quasi homogeneous and homeotropic liquid crystal cells using weak anchoring surfaces

Rumiko YAMAGUCHI

IEICE TRANS. ELECTRON ( The Institute of Electronics, Information and Communication Engineers ) E102-C ( 11 ) 810 - 812 2019年11月 [査読有り]

研究論文（学術雑誌）単著

Liquid crystal director distributions between strong and weak polar anchoring surfaces in hybrid aligned cells are numerically analyzed. When the anchoring is a critical one, homogeneously or homeotropicly liquid crystal alignment can be obtained. Such cells have no threshold voltage and a driving voltage can be reduced less than 0.5 volt. © 2019 The Institute of Electronics, Information and Communication Engineers.

DOI

Louver function in hybrid aligned reverse mode using dual frequency liquid crystal

Yamaguchi Rumiko, Ushizaki Ryo

Journal of Photopolymer Science and Technology ( Journal of Photopolymer Science and Technology ) 32 ( 4 ) 545 - 548 2019年04月 [査読有り]

研究論文（学術雑誌）国内共著

<p>We have proposed reverse mode liquid crystal (LC) cells with a hybrid alignment nematic (HAN). A dual frequency LC which has positive and negative dielectric anisotropies and a reactive mesogen were used to prepare the cell. The reverse mode HAN cell has a transparent state at any incident angle in the voltage off state. The cell scattered a normal incident light by the voltage application and the transmittance, however, becomes high at a certain oblique incident angle like a louver of a window shutter. Such an incident angle can be switched by the frequency of applied voltage since the reoriented LC director changes from perpendicular to parallel to the substrate. Moreover, the incident angle switching was theoretically analyzed using conditions of refractive index matching and mismatching between the LC and the reactive mesogen.</p>

DOI

Driving Voltage in Reverse Mode Cell Using Reactive Mesogen : Effect of UV Absorption of Liquid Crystal

Rumiko Yamaguchi, Ryosuke Sasaki, and Koichi Inoue

Journal of Photopolymer Science and Technology ( The Society of Photopolymer Science and Technology ) 31 ( 3 ) 301 - 304 2018年06月 [査読有り]

研究論文（学術雑誌）国内共著

We have proposed reverse mode liquid crystal (LC) cells by using a polymer stabilized LC technology. A reactive mesogen was dissolved in the LC and was polymerized by UV light from an Hg lamp (313 nm) and a UV-LED (365 nm) light sources. LC materials with and without UV absorption at each wavelength were prepared and electro-optical properties of the reverse mode cell were measured. It was found that the electro-optical property strongly depended on the UV absorption of the LC. Next we mixed LCs with and without UV absorption to adjust the UV intensity profile in the bulk of the LC cell. We successfully reduced the driving voltage by changing the absorption coefficient of LC mixtures.

DOI

Effect of Liquid Crystal Material on Polymer Network Structure in Polymer Stabilized Liquid Crystal Cell

Rumiko Yamaguchi, Kota Inoue, Ryo Kurosawa

Journal of Photopolymer Science and Technology 29 ( 2 ) 289 - 292 2016年08月 [査読有り]

研究論文（学術雑誌）国内共著

Polymer stabilized liquid crystal (PSLC) cells have been fabricated by using a reactive
mesogen (RM) and various LC materials. It is clarified that a polymer network structure
changes by selecting not only RM but also LC materials. Using the LC with a tolane
substance, a “rice grain like” morphology can be obtained, which results in low threshold and
driving voltages even if a dielectric constant anisotropy of the LC is very small. On the other
hand, a “smooth stranded network” morphology causes the high driving voltage. When two
LC materials which contribute to the smooth stranded network morphology are mixed and
the LC mixture is used to fabricate the PSLC cell, the rice grain like morphology is formed.
The driving voltage is lower than that in cells using two pure LCs. A relationship between
solubility of the RM in the LC and the morphology formation is not observed.

DOI

Driving voltage properties sensitive to microscale liquid crystal orientation pattern in twisted nematic liquid crystal cells

Michinori Honma, Koki Takahashi, Rumiko Yamaguchi, Toshiaki Nose

Japanese Journal of Applied Physics ( 55 ) 041701-1 - 041701-6 2016年03月 [査読有り]

研究論文（学術雑誌）国内共著

We investigated the micropattern-sensitive driving voltage properties of twisted nematic liquid crystal (LC) cells and found that the threshold
voltage for inducing the Fréedericksz transition strongly depends on the micropatterned LC molecular orientation state. We discuss the effects
of various cell parameters such as the period of the micropattern Λ, the LC layer thickness d, and the twist angle Φ on the threshold voltage.
By a computer simulation of the LC molecular orientation, we found that the threshold voltage Vth varies in response to the deformation factor Δ
(= d2/Λ2 + Φ2/π2) of the spatially distributed LC molecular orientation. We confirm that V2
th is proportional to 1 % Δ from both theoretical and
experimental standpoints.

DOI

UV penetration depth in hybrid-aligned reverse mode liquid crystal cell

Yamaguchi R.

Digest of Technical Papers - SID International Symposium ( Digest of Technical Papers - SID International Symposium ) 46 2015年12月 [査読有り]

研究論文（学術雑誌）

DOI

Normal and reverse mode light scattering properties in nematic liquid crystal cell using polymer stabilized effect

Yamaguchi R.

Journal of Photopolymer Science and Technology ( Journal of Photopolymer Science and Technology ) 28 ( 3 ) 319 - 323 2015年10月 [査読有り]

研究論文（学術雑誌）

DOI

Hybrid aligned nematic liquid crystal smart glass with asymmetrical daylight controls