Analog circuit producing a nonlinear luminance versus drive voltage characteristic, for use in an LCD

摘要

So as to make a composing unit (R7, 33) produce a composite signal of a drive voltage for use in producing a driving signal for an LCD having a liminance versus drive voltage characteristic curve approximated by a nonlinear curve generated by a concatenation of at least first through third linear function curves, an analog nonlinear operation circuit (15) comprises first through third amplifier circuits (31(1) - 31(3)) for generating first through third function voltages in correspondence to the first through the third linear function curves. The amplifier circuits are typically differential amplifiers particularly when the operation circuit is applied to gamma compensation of television video signal for a CRT into a gamma compensated signal which is for the LCD and is produced as the composite signal. In this event, the amplifier circuits are supplied in common with the video signal and respectively with low, middle, and high reference voltages defined by white, intermediate, and black levels of the video signal.