Department of Information Systems Engineering

Usami Kiyoaki

  (宇佐美 清章)

Profile Information

Affiliation
Professor, Faculty of Design Technology, Department of Information Systems Engineering, Osaka Sangyo University
Degree
博士(工学)(東北大学)

Researcher number
40360507
J-GLOBAL ID
200901040318348219
researchmap Member ID
5000102561

Papers

 16
  • Kenji Sakamoto, Kiyoaki Usami, Shogo Kiyohara, Kazushi Miki
    Proceedings of SPIE, 9940 994008-1-994008-9, Nov 28, 2016  Peer-reviewedInvited
  • Kenji Sakamoto, Kiyoaki Usami, Kazushi Miki
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 611(1) 153-159, Apr, 2015  Peer-reviewed
    Photo-alignment efficiency of polyimide containing azobenzene in the backbone structure (Azo-PI) is significantly enhanced by exposing the precursor (polyamic acid: Azo-PAA) film to alkyl-amine vapor prior to photo-alignment. In this study, we have investigated the relationships between the alkyl-amine vapor treatment time, the swelling ratio of Azo-PAA films, and the photo-induced in-plane anisotropy. We found that: the Azo-PAA film swells on exposure to alkyl-amine vapor, and the swelling finally saturates; and the photo-induced in-plane anisotropy is correlated very closely with the swelling ratio. In addition, we pointed out the importance of the process order of alkyl-amine vapor treatment and photo-alignment.
  • Kenji Sakamoto, ati, Materials Science, Kiyoaki Usami, Kazushi Miki
    Applied Physics Express, 7(8) 081701, Jul, 2014  Peer-reviewed
  • M. Nagaraj, K. Usami, Z. Zhang, V. Görtz, J. W. Goodby, H. F. Gleeson
    Liquid Crystals, 41(6) 800-811, 2014  Peer-reviewed
    Unusual behaviour of the dark conglomerate (DC) phase seen in an oxadiazole-based achiral bent-core liquid crystal, which has not previously been reported for the DC phase of other liquid crystals, is described. Under polarising optical microscopy, we see no domains of opposite handedness in the ground state of the DC phase. However, it shows unusual transformations when an electric field is applied to the system. On increasing the electric field, at first the domains of opposite handedness become visible and then they grow in size and slowly the sample transforms to a monochiral or single-handed form which is followed by a nonchiral state at very high fields. The threshold electric fields required to achieve these changes are temperature dependent and the transformations are seen irrespective of the frequency of the applied electric field (100 Hz to 5 kHz), type of the waveform (sine, square and triangular) and the thickness (1.5 μm to 15 μm) or the geometry (planar and twisted) of the device used. Further, there is no field-induced high birefringence texture observed even though sufficiently large electric field (~22 V/μm) has been applied across the devices. The nature of the behaviour is investigated by various techniques such as optical microscopy, conoscopy, circular dichroic and Raman spectroscopies, electro-optics and dielectric spectroscopy. The possible physical phenomena behind these changes are discussed in detail. © 2014 Taylor &amp Francis.
  • Kiyoaki Usami, Kenji Sakamoto
    JOURNAL OF APPLIED PHYSICS, 110(4) 043522, Aug, 2011  Peer-reviewed
    We have succeeded in controlling the pretilt angle of liquid crystal (LC) molecules over the whole range of 0 to 90 degrees by using photo-aligned blend films of two azobenzene-containing polyimides (Azo-PIs) with and without side-chains. The Azo-PIs were synthesized from pyromellitic dianhydride and a mixture of 4,4'-diaminoazobenzene and 4-(4'-propylbi(cyclohexan)-4-yl)phenyl 3,5-diaminobenzoate (PBCP-DABA). PBCP-DABA is a diamine to introduce a side-chain structure into the polyimide. Defect-free uniform LC alignment was obtained in the pretilt angle (theta(p)) ranges of theta(p) <= 11 degrees and theta(p) >= 78 degrees. Previously, we reported that the pretilt angle can be controlled using pure photo-aligned films of Azo-PIs with different molar fractions of PBCP-DABA. For the pure photo-aligned films, the defect-free pretilt angle ranges were theta(p) < 5 degrees and theta(p) >= 85 degrees. These results suggest that the azimuthal anchoring strength of the blend Azo-PI film is stronger than that of the pure films of Azo-PIs with side-chains, at least for the pretilt angle range from 5 to 11 degrees. We found that the defect-free pretilt angle range can be extended by using the blend Azo-PI films instead of the pure Azo-PI films. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624767]

Books and Other Publications

 1
  • 安達千波矢, 家地洋之, 式会社リコー, 伊東栄次, 岩本光正, 宇佐美清章, 大澤利幸, 株式会社KRI, 小野田光宣, 鎌田俊英, 産業技術総合研究所, 京兼純(奈良工業高等専門学校, 工藤一浩, 久保田徹, 通信研究機構, 島田敏宏, 杉村明彦, 多田和也, 田中祀捷, 藤井彰彦, 間中孝彰, 宮原裕二, 物質, 材料研究機構, 村田義直, 株式会社ジェイ・パワーシステムズ, 森田成紀, 和田恭雄 (Role: Joint author)
    オーム社, Mar, 2007
    本書は柔構造を有機エレクトロニクス研究に関する現状と将来展望をまとめたものである。有機薄膜作製技術と評価方法、液晶分子のダイナミクス、ナノコンポジット技術、有機電子光機能デバイス、有機単一電子トランジスタ素子などが取り上げられている。

Presentations

 71

Professional Memberships

 4

Social Activities

 2

研究テーマ

 1
  • 研究テーマ(英語)
    光配向法による液晶の分子配向制御
    キーワード(英語)
    液晶、配向膜、光配向、ポリイミド
    概要(英語)
    偏光紫外光による異方的な光化学反応を利用した液晶分子の表面配向制御法に関する研究