System for converting number of lines of television signal

A system for converting the number of lines of an input television signal having frames each formed by two adjacent interlaced fields comprising:

• input terminal means for receiving said input television signal:
• memory means connected to said input terminal means for successively storing said input television signal;
• first synchronizing terminal means for receiving horizontal synchronizing pulses and vertical synchronizing pulses of said input television signal;
• second synchronizing terminal means for receiving horizontal synchronizing pulses and vertical synchronizing pulses of an output television signal to be obtained;
• address circuit means connected to said memory means, said first synchronizing terminal means and said second synchronizing terminal means for performing the write-in operation to the memory means in response to said horizontal synchronizing pulses and said vertical synchronizing pulses of the first synchronizing terminal means and for performing the read-out operation from the memory means in response to said horizontal synchronizing pulses and said vertical synchronizing pulses of said second synchronizing terminal means;
• detection means connected to said memory means for detecting from the contents of said memory means, moving picture areas of said frames each formed by a block of successive moving picture elements, each of which has a level difference more than a predetermined threshold level from the level of a corresponding picture element in an immediately preceding frame of said input television signal, and for generating a moving area detection signal in response to each detection of said moving picture areas;
• line combiner means connecting said memory means, said detection means and said second synchronizing terminal means for forming each interlaced frame of said output television signal by signals of two adjacent fields of said input television signal read-out from said memory means in response to said moving area detection signal, said horizontal synchronizing pulses of said second synchronizing terminal means under a condition where signals of each field of said each frame of said output television signal are formed by sequentially weighting and combining line signals of the former and the latter of the two fields of said input television signal, so that the order of lines is not reversed in said output frame while the lines are not repeated in the same field, and under a condition where the weight factor of said weighting and combining is constant for said moving picture area but variable for each stational picture area other than said moving picture area in accordance with a distance between an instant line signal of said output frame and a line signal of the same field to be combined with said instant line signal;
• and
• output terminal means connected to said line combiner means for obtaining said output television signal.