Patent ID: 7576803
Filing Date: 2009-08-18
Classification: G09G,H04N

Abstract:
1. A processing circuit, used to simplify a plurality of types of input signal to a single type of signal, the processing circuit comprising: a first polarity converter for receiving a first synchronization signal, reversing polarity of the first synchronization signal, and outputting a second synchronization signal, wherein the first synchronization signal is selected from the group consisting of a horizontal synchronization signal without vertical synchronization signal composition, and a horizontal synchronization signal with vertical synchronization signal composition combined therein; a second polarity converter, wherein when a first vertical synchronization signal exists, the second polarity converter reverses polarity of the first vertical synchronization signal, and outputs a second vertical synchronization signal; an extraction circuit for extracting the vertical synchronization signal composition from the second synchronization signal; a removal circuit for removing the vertical synchronization signal composition from the second synchronization signal; a detection circuit for detecting whether there is the second vertical synchronization signal outputted from the second polarity converter; and a selection circuit, responsive to the detection circuit, wherein when the second vertical synchronization signal exists, the selection circuit outputs the second vertical synchronization signal, and when the second vertical synchronization signal doesn't exist, the selection circuit outputs the vertical synchronization signal composition.