Television receiver including a circuit for doubling line scanning frequency

Claim 1

A television receiver comprising: an input terminal for receiving first video signals which include character information signals during vertical blanking periods where a character signal of an odd interlaced field is identical with a character signal of a succeeding even field; a character decoder connected to said input terminal for detecting said information signals and converting the same to second video signals, first switching means connected to said input terminal and said character decoder for switchably selecting one of said first and second video signals, a scanning converter connected to said first switching means for doubling the frequency of the selected video signals, a display means, means for supplying said frequency doubled video signals to said display means for a visual display, including field identification means connected to said input terminal for detecting odd fields from even fields, and control means connected to said field identification means and said display means for controlling the scanning of said display means such that the scanning of the lines of said odd fields are substantially delayed by H/2 where H is the normal horizontal scanning period with respect to those of said even fields, and wherein said means for supplying said frequency doubled video signals includes a delay circuit of H/2 connected to said scanning converter and second switching means for switchably supplying one of the input and output signals of said delay circuit to said display means and wherein said control means controls said second switching means and wherein an interlaced signal is converted to a non-interlaced signal and wherein corresponding lines of the even and odd fields beginning with the first line in each field are superimposed and each such superimposed line is scanned twice on said display means.