Color television signal generating apparatus having circuit for reducing noise in output primary color signals of camera tube having color-resolving striped filter

Claim 1

A color television signal generating apparatus comprising: a color-resolving striped filter comprising a plurality of groups of filter stripes, said groups being disposed in parallel and consecutively in a sequentially repeated arrangement, each of said groups comprising first, second and third filter stripes, said first filter stripe having a light transmission characteristic for transmitting the light of one of three additive primary colors, said second filter stripe having a light transmission characteristic for transmitting the light of a mixed color which includes said one of the three additive primary colors and another of the remaining two additive primary colors, and said third filter stripe being transparent and transmitting white light, said first, second and third filter stripes being arranged in parallel and consecutively in a predetermined sequence; a camera tube having said color-resolving striped filter disposed on the front surface thereof, said camera tube having a scanning electron beam of predetermined scanning speed; first separating means for separating and deriving, from an output signal of the camera tube, a fundamental component in which a carrier having a frequency equal to a space frequency being determined by the pitch of said groups of filter stripes in said color-resolving striped filter is amplitude-modulated; second separating means for separating and deriving, from the output signal of the camera tube, a second order harmonic component in which a carrier having a frequency twice the space frequency is amplitude-modulated; multiplying means for multiplying an output signal of said first separating means by an output signal of said second separating means; obtaining means for separating and obtaining two primary color signals corresponding to said remaining two additive primary colors from an output signal of said multiplying means and the output signal of said first separating means; a noise reduction circuit for reducing noise in said two primary color signals which are obtained from said obtaining means and for producing two primary color signals in which the noise has been reduced; third separating means for separating and deriving, from the output signal of the camera tube, a DC component signal containing signals corresponding to all of said three additive primary colors; and matrix means, responsive to the primary color signals from said noise reduction circuit and to the separated DC component signal from said third separating means, for producing three primary color signals, said noise reduction circuit comprising a first subtracting circuit supplied with the two primary color signals from said obtaining means for performing a subtracting operation between the signals supplied thereto, an amplitude limiter for amplitude-limiting an output signal of said first subtracting circuit to a level of a noise component which is included within the output signal of said first subtracting circuit, a second subtracting circuit supplied with a first primary color signal which is one of the primary color signals from said obtaining means and an output signal of said amplitude limiter for performing a subtracting operation between the signals supplied thereto, and a first adder supplied with a second primary color signal which is the other of the two primary color signals from said obtaining means and the output signal of said amplitude limiter for performing an adding operation between the signals supplied thereto, said second subtracting circuit and said first adder respectively producing the two primary color signals in which the noise has been reduced.