IMAGE DISPLAY DEVICE

摘要

A signal identifying and monitoring circuit includes a full black detecting circuit that detects full black of an image signal and outputs a black detection signal indicating the detected result and that outputs the black detection signal with a required pulse width when the image signal is interrupted for a predetermined period of time. The signal identifying and monitoring circuit detects whether or not the resolution of the input image signal is changed by determining whether or not the frequency of a horizontal synchronizing signal included in the image signal of a frame to be input next is changed by more than or equal to a predetermined value set in advance when the black detection signal is output from the full black detecting circuit. When a change in the resolution of the image signal is detected, the signal identifying and monitoring circuit outputs a change detection signal indicating the detected result. A scaling circuit outputs an image display signal of a fixed value when the scaling circuit receives the change detection signal so that the displayed image becomes frozen.