APPARATUS FOR ADAPTIVELY GENERATING VERTICAL BLANK OF VIDEO SIGNALS IN PDP TV

摘要

The present invention provides an adaptation for a PDP television that can effectively generate a vertical blank signal suitable for setting the vertical position of a video screen when displaying on a panel an image mode having at least fewer lines than a display panel. The present invention relates to a vertical blank generating device. To this end, the present invention relates to a vertical blank generating device, and generates a selection pulse by determining a mode for each size of an input image based on horizontal and vertical synchronization signals detected from the input image. A mode discrimination and pulse shaping block for generating a field discrimination signal and matching the polarity of the vertical frequency detected in the input image equally; A shift register generating a new vertical synchronizing signal by shifting the detected vertical synchronizing signal by a predetermined 22H line based on the detected horizontal synchronizing signal; A buffer block for buffering the generated selection pulse, the field separation signal, the detected horizontal synchronization signal and the new vertical synchronization signal for timing synchronization between the signals; On the basis of the detected horizontal synchronizing signal provided in the buffer block and the new vertical synchronizing signal, the generated new vertical synchronizing periods 23H to 449H are divided into 20H and 445H to 15H lines between 25H to 44H lines for each field. First counters each generating a blank pulse; In response to the generated selection pulse provided by the buffer block, the detected horizontal and new vertical sync signals are inputted to count the active sections within the new vertical sync section, and between 45H to 444H lines of each vertical section of 23H to 449H lines. A second counter for detecting an active period of each; Logic means for generating a horizontal sync pulse in the detected active section through a logical product operation between the detected horizontal sync signal and the detected active section provided from the second counter; A frequency multiplier for frequency division of the horizontal sync pulses in the active section provided by the logic means to generate horizontal sync pulses divided by N times to generate a vertical section having an odd field of 200H odd lines in the active section; An inverter for inverting the N-fold divided horizontal synchronizing pulses to generate a vertical section having horizontal synchronizing pulses for an odd field of even lines of 200H in an active period; And a vertical blank signal for an odd field made by combining a vertical section having a blank pulse provided from the first counter and a horizontal sync pulse for an odd field of odd lines in response to the generated selection pulse and the generated field separation signal. And a vertical blank selection block that alternately generates a vertical blank signal for an even field made by combining a blank pulse provided at one counter and a vertical section having horizontal sync pulses for an odd field of even lines.