Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Optical excitation
Patent
1997-04-23
2000-02-29
Sikes, William L.
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Optical excitation
349 13, 348341, 348207, 351 44, 345 7, G02F 1135
Patent
active
060315881
ABSTRACT:
A device featuring liquid crystals for local reduction of the intensity of incident light is described. This device protects the eyes or the video camera against blinding, or the light-sensitive medium against local damage by automatically reducing the intensity of the incident light emitted by brightly illuminated objects, while the brightness of poorly illuminated objects is not suppressed. The device uses optically addressed spatial light modulators (OASLM) on the basis of a semitransparent photoconducting film in contact with ferroelectric liquid crystals (FLC). The DHF effect (deformation of the helix structure) in ferroelectric liquid crystals (FLC) with helix-shaped structure is used here. The drive voltage has a frequency of 10.sup.2 to 10.sup.3 Hz at an amplitude of .+-.20 V, which is 10-50 times higher than that of devices operating with nematic liquid crystals. The device allows moving objects to be observed against the background of a bright light source (sun, lamp, etc.). A switchable shutter on the basis of ferroelectric liquid crystals (FLC) is used at a molecular inclination of .theta..sub.o .noteq.45.degree.. To increase the average transmission of the device, a second FLC layer with chiral smectic A or C phase with a switchable molecular inclination of .theta..sub.c =45.degree.-.theta..sub.o or .theta..sub.c =.theta..sub.o is used.
REFERENCES:
patent: 4462661 (1984-07-01), Witt
patent: 4842400 (1989-06-01), Klein
patent: 4848890 (1989-07-01), Horn
patent: 4968127 (1990-11-01), Russell et al.
patent: 5015086 (1991-05-01), Okaue et al.
patent: 5056897 (1991-10-01), Akiyama et al.
patent: 5073010 (1991-12-01), Johnson et al.
patent: 5081542 (1992-01-01), Efron et al.
patent: 5085498 (1992-02-01), Yamamoto et al.
patent: 5298732 (1994-03-01), Chen
patent: 5353080 (1994-10-01), Christman
patent: 5420709 (1995-05-01), Kato et al.
patent: 5608567 (1997-03-01), Grupp
Tomilin, M. et al., "Safety Goggles With Local-Space Modulation," Mol. Cryst. Liq. Cryst., 1992, vol. 222, pp. 119-124.
Beresnev, L. et al., "Deformed helix ferroelectric liquid crysta display: a new electrooptic mode in ferroelectric chiral smectic C liquid crystals," Liquid Crystals, 1989, vol. 5, No. 4, pp. 1171-1177.
Beresnev, L. et al., "X-Ray And Optical Investigations Of The Dislocation Domains In Ferroelectric Liquid Crystals," pp. 1-13, Figs. 1-14.
Patent Abstracts of Japan 6-148598 (A), P-1791, Aug. 24, 1994, vol. 18, No. 454.
Patent Abstracts of Japan 4-141626 (A), P-1413, Sep. 3, 1992, vol. 16, No. 418.
Patent Abstracts of Japan 1-302226 (A), P-1010, Feb. 21, 1990, vol. 14, No. 94.
Patent Abstracts of Japan 60-230121 (A), P-446, Apr. 15, 1986, vol. 10, No. 97.
Patent Abstracts of Japan 60-254120 (A), P-456, May 16, 1986, vol. 10, No. 132.
Patent Abstracts of Japan 07306421(A) Nov. 21, 1995.
Beresnev Leonid
Dultz Wolfgang
Haase Wolfgang
Onokhov Arkadii
Deutsche Telekom AG
Hollingshead Robert J.
Sikes William L.
LandOfFree
Ferroelectric liquid crystal device for local reduction of light does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ferroelectric liquid crystal device for local reduction of light, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ferroelectric liquid crystal device for local reduction of light will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-687812