Patent ID: 7283179

Claim:
A liquid crystal television apparatus comprising: a liquid crystal panel whose display surface is formed of a plurality of pixels; a tuner for receiving a television signal of a desired frequency corresponding to a television broadcast band via an antenna, for selecting only a required signal from the received television signal and applying high frequency amplification to the selected signal, and for outputting an analog video signal converted to an intermediate frequency signal; an analog-to-digital conversion circuit for inputting the analog video signal from the tuner and for converting a predetermined signal level range of the analog video signal to a digital signal having gradation corresponding to the signal levels; a signal process circuit for generating a digital video signal by applying a predetermined digital signal process to the converted digital signal to generate a digital video signal; a flame memory circuit for storing a digital video signal forming an image for one screen displayed on the liquid crystal panel while inputting the generated digital video signal; a liquid crystal driver circuit for displaying the image on the liquid crystal panel while applying a predetermined signal process to the digital video signal stored in the flame memory circuit; a microcomputer for controlling the circuits, wherein the analog-to-digital conversion circuit changes the signal level range; and wherein the apparatus further comprises: an image luminance detection circuit for detecting a luminance of a predetermined area of the image or an average luminance of a plurality of areas of the image in accordance with the digital video signal stored in the flame memory; a determination circuit for determining whether the detected luminance of the predetermined area or the average luminance of a plurality of the areas is equal to or over a threshold showing that the image is bright; and a conversion control circuit for outputting a predetermined control signal to the analog-to-digital conversion circuit and expanding an upper limit of a signal level range of the analog video signal to be converted to the digital signal to change the signal level range when the detected luminance of the predetermined area or the average luminance of a plurality of the areas is determined to be equal to or over the threshold.