Liquid-crystal luminaire consisting of an optical shutter and a metal halide lamp.
We made a liquid-crystal (LC) luminaire for the first time to our knowledge by combining a metal halide lamp and an optical shutter composed of a compound of a very high nematic-isotropic point (172 degrees C) LC and a polymer (CLCP). The shutter can modulate high-power light independently of the state of polarization because the CLCP film becomes transparent or opalescent when either sufficiently high or no voltage is applied to it. To solve the problem, which is peculiar to CLCP films, that the color temperature of light modulated by the film changes with the film's transmittance, a pulse-width modulation method that varies the time ratio of the on and off states of the shutter was developed. The performance characteristics of the luminaire were as follows: illuminance range, 192 to 10,400 lx at a distance of 5 m from the luminaire; rise and decay times, 1.4 and 1.5 ms; color temperature, 4060-5600 K; operation room temperature, approximately 150 degrees C; stable operation time, more than 2000 h. Experimental results show the feasibility of applications of this luminaire in various fields, including television, movie, and stage lighting.
Takizawa
K
K
Science and Technical Research Laboratories, Japan Broadcasting Corporation, 1-10-11 Kinuta, Setagaya-ku, Tokyo 157-8510, Japan. takizawa@strl.nhk.or.jp
Fujii
T
T
Fujikake
H
H
Hirabayashi
T
T
Tanaka
Y
Y
Hara
K
K
Takano
S
S
Asakawa
H
H
Kita
H
H