Patent ID: 6078317
Filing Date: 2000-06-20
Classification: G06T,G09G,H03L

Abstract:
A display control apparatus for displaying an image on a display screen by receiving a video signal including an image signal and a synchronizing signal, sampling the video signal in synchronism with a clock signal, and converting the video signal into a digit al signal, said apparatus comprising:display mode detection mean s for detecting a current display mode on the basis of the synchronizing signal in the video signal;frequency division means for dividing a frequency of the clock signal by using a frequency division value and for outputting a frequency divided clock signal;comparison means for comparing the frequency divided clock signal with the synchronizing signal and outputting a difference signal indicating a phase difference between the frequency divided clock signal and the synchronizing signal;a plurality of low-pass filter means, each of which having a different low-pass frequency from each other, for filtering an inputted signal and outputting a filtered signal;a plurality of clock generating means, each of which is connected to one of the plurality of low-pass filter means, for generating clock signals having different frequencies from each other;selection means for selecting one of the clock signals generated by the plurality of clock generating means based on the current display mode detected by said display mode detection means, such that the selected clock signal has a higher frequency than that of the clock signal corresponding to the current display mode when the number of pixels in a horizontal direction in the current display mode is less than the number of pixels in a horizontal direction of the display screen;sampling means for sampling the video signal in synchronism with a selected clock signal selected by said selection means, such that a resolution of a sampled video signal by said sampling means corresponds to a resolution of the display screen;converting means for converting the sampled video signal into a digital signal; andoutput means for outputting a video signal sampled by said sampling means and converted by said converting means to the display.