T. Shiga et al., IMPROVING THE LUMINANCE AND LUMINOUS EFFICACY OF MINIATURE FLUORESCENT LAMPS FOR LIQUID-CRYSTAL DISPLAY BACKLIGHTING BY USING A DOUBLE FREQUENCY DRIVE, Review of scientific instruments, 69(9), 1998, pp. 3426-3432
A new method of driving miniature fluorescent tubes for liquid crystal
display backlighting, with diameters as small as 2 mm, has been devis
ed with the objective of improving the luminance and luminous efficaci
es of such lamps. The driver voltage wave form consists of high freque
ncy oscillations at the leading and trailing edges of conventional squ
are-wave form voltage pulses of relatively low frequency. The wave for
m is produced simply by inserting coils between low frequency square-w
ave pulse generators and the lamp electrodes. A lamp driven in this wa
y operates in a different discharge mode from the conventional glow di
scharge obtained in the absence of the coils. The twofold intensity in
crease of visible emission from the positive column region indicates t
hat the vacuum ultraviolet emission increases: enhancing the excitatio
n of the phosphor in the lamp, There is evidence that the luminous eff
icacy is also increased by a factor of 2 as a result of more efficient
use of the input energy. The minimum voltage needed to maintain a dis
charge is reduced. (C) 1998 American Institute of Physics. [S0034-6748
(98)04409-8]