Appendix
Bac
Backlighting Brightne
r Panasonic’s line of LCD TVs is accomplished through the
use of Cold Cathode Fluorescent tubes (CCFT), which is currently the light source of
choice, by a number of leading manufacturers.
Inverter Power Supply
Pulse width modulation is a very straightforward m
f
the CCF tube(s). The inverter is turned on and off (using the input or an enable/disable
line) from the Microprocessor Unit (MPU) to contr
cycle
is lengthened to increase the brightness and reduced to decrease the brightness. One
of the major advantages of pulse width modulation is the
“off” and full starting voltage is always applied to the tube(s) (assuming nominal input
voltage). Figure 5 is a simplified diagram of a pul
DC to AC inverter.
klighting
ss fo
ethod for controlling the brightness o
ol the brightness. The “on” duty
tube is always fully “on” or fully
se width modulated
Figure 32
46
