Digital television receiver

Claim 2

A digital television receiver comprising: digital converter means (102 to 109, 112 to 124) for converting an analog video signal (101) to a digital video signal (110); signal separator means (126 to 129) coupled to said digital converter means (109), for separating a digital chrominance signal (130) and a digital luminance signal (133) from said digital video signal (110); color killer means (135) coupled to said signal separator means (128) and being responsive to burst components of said digital chrominance signal (130), for gating said digital chrominance signal (130) to generate a gated color signal (138) when said burst components are contained in said digital chrominance signal (130); and processor means (139 to 144) coupled to said signal separator means (129) and to said color killer means (135), for digitally composing RGB signals (145) from said digital luminance signal (l33) and said gated color signal (138), said RGB signals (145) being used as tricolor signals for a color picture tube.

Claim 3

A receiver according to claim 1, characterized in that said color killer means (135) includes: multiplier means (1401) for digitally multiplying said digital chrominance signal (130) by an amplitude control signal (1402) and providing a multiplied chrominance signal (1403); comparator means (1511, 1513) for comparing a color control signal (136) and said amplitude control signal (1402), and generating a color killer signal (137) when a result of comparison of said comparator means (1513) indicates that a predetermined relation between said color control signal (136) and said amplitude control signal (1402) is established; gate means (1514) coupled to said multiplier means (1401) and to said comparator means (1513), for passing said multiplied chrominance signal (1403) to provide said gated color signal (138) when said color killer signal (137) is generated; burst detector means (1404) responsive to a color signal (1403) corresponding to said digital chrominance signal (130), for detecting said burst components from said color signal (1403) and generating a burst amplitude signal (1405); and control signal means (1406, 1408) coupled to said burst detector means (1404) and being responsive to said color control signal (136), for generating said amplitude control signal (1402) in accordance with a difference between said burst amplitude signal (1405) and said color control signal (136).

Claim 4

A receiver according to-claim 2, characterized in that said control signal means (1406, 1408) includes: subtractor means (1406) coupled to said burst detector means (1404), for detecting an error signal (1407) corresponding to a difference between said burst amplitude signal (1405) and said color control signal (136); and filter means (1408) coupled to said subtractor means (1406), for digitally filtering said error signal (1407) and generating said amplitude control signal (1402), said burst detector means (1404), subtractor means (1406), filter means (1408) and multiplier means (1401) constituting an automatic chroma control loop, and said filter means (1408) determining a signal delay rate or time constant of said automatic chroma control loop.

Claim 5

A receiver according to claim 3, characterized in that said error signal (1407) is a digital data, and characterized in that said filter means (1408) includes: bit-shift means j1507) for shifting the digital data of said error signal (1407) toward the least significant bit side and generating a bit-shifted signal; and accumulator means (1508 to 1510) coupled to said bit-shift means (1507), for accumulating said bit-shifted signal with a given timing and generating said amplitude control signal (1402).

Claim 6

A receiver according to any one of claims 2 to 4, characterized in that said burst detector means (1404) includes: burst extractor means (1501) for extracting said burst components from said color signal (1403) and generating an extracted signal (E1501) corresponding to said burst components; absolute value means (1502) coupled to said burst extractor means (1501), for detecting the absolute value of said extracted signal (El50l) and generating an absolute signal (1503) corresponding to said absolute value; and burst accumulator means (1504 to 1506) coupled to said absolute value means (1502), for accumulating said absolute signal (1503) with a given timing and generating said burst amplitude signal (1405).

Claim 7

A receiver according to any one of claims l.to 5, characterized in that said signal separator means (126 to 129) includes: delay means (126) for delaying said digital video signal (110) by a given amount (2TH) to provide a delayed video signal (127); Y/C separator means (128) coupled to said delay means (126) for separating said digital chrominance signal (130) and an unprocessed luminance signal (131) from said delayed video signal (127); and Y processor means (129) coupled to said delay means (126) and said Y/C separator means (128), for composing said digital luminance signal (133) from said delayed video signal (127) and said unprocessed luminance signal (131).

Claim 8

A receiver according to claim 6, characterized in that said Y processor means (129) includes: contrast means (703) coupled to said delay means (126), for varying the contrast component of said delayed video signal (127) and generating a varied signal (710) corresponding to said contrast components; and combine means (711, 713) coupled to said contrast means (703) and to said Y/C separator means (128), for combining said varied signal (710) and said unprocessed luminance signal (131) and generating as the result of combining said digital luminance signal (133).

Claim 9

A receiver according to claim 7, characterized in that said contrast means (703) includes: contrast accumulator means (1301) for accumulating said delayed video signal (127 or 404) to generate an accumulated signal (1302); average means (1303) coupled to said contrast accumulator means (1301), for averaging said accumulated signal (1302) for a given period of time (lH) to generate an averaged signal (1304); and contrast filter means (1336) coupled to said average means (1303), for smoothing the potential change of said averaged signal (1304) to generate a filtered signal (1337); means (1305 to 1309) coupled to said delay means (126) and to said contrast filter means (1336) and being responsive to a coefficient signal (706), for generating said varied signal (710) from said delayed video signal (127 or 405) and said filtered signal (1337) so that the difference between said delayed video signal (405) and said filtered signal (1337) corresponds to said varied signal (710), the magnitude of said varied signal (710) depending on said coefficient signal (706).

Claim 10

A receiver according to claim 7 or 8, characterized in that saic Y prccessor means (129) further includes: V contour means (701) coupled to said delay means (126), for generating a vertical contour signal (708) from said delayed video signal (127) and supplying said vertical contour signal (708) to said combine means (711) so that said digital luminance signal (133) contains a signal component of said vertical coutour signal (708) which modifies the vertical contour of pictures displayed at a CRT.

Claim 11

A receiver according to claim 9, characterized in that said V contour means (701) includes: V differential means (802 to 805) for differentiating signal components of said delayed video signal (127) for a prescribed period of time (2H) to generate a V differentiated signal (806); V filter means (807) coupled to said V differential means (805), for digitally low-pass filtering said V differentiated signal (806) to generate a V filtered signal (818); and V coefficient means (819) coupled to said V filter means (807) and being responsive to a V coefficient signal (704), for multiplying said V filtered signal (818) by said V coefficient signal (704) to generate said vertical coutour signal (708).

Claim 12

A receiver according to claim 7 or 8, characterized in that said Y processor means (129) further includes: H contour means (702) coupled to said delay means (126), for generating a horizontal contour signal (709) from said delayed video signal (127) and supplying said horizontal contour signal (709) to said combine means (711) so that said digital luminance signal (133) contains a signal component of said horizontal contour signal (709) which modifies the horizontal contour of pictures displayed at a CRT.

Claim 13

A receiver according to claim 11, characterized in that said H contour means (702) includes: V average means (902 to 905) for averaging signal components of said delayed video signal (127) for a prescribed period of time (2H) to generate an averaged signal (906); H filter means (907) coupled to said V average means (905), for digitally low-pass filtering said averaged signal (906) to generate an H filtered signal (914); and H coefficient means (915) coupled to said H filter means (907) and being responsive to an H coefficient signal (705), for multiplying said H filtered signal (914) by said H coefficient signal (705) to generate said horizontal contour signal (709).

Claim 14

A receiver according to any one of claims 1 to 12, characterized in that said color killer means (135) includes: means (1401, 1404, 1406, 140-8, 1511, 1513) responsive to said digital chrominance.signal (130), for generating a color killer signal (137) when said burst components do not contained in said digital chrominance signal (130); and wherein said signal separator means (128) includes: killer gate means (421) coupled to said color killer means (135) and being responsive to said color killer signal (137), for passing said digital chrominance signal (130) as a gated signal (422) when said color killer signal (137) disappears, and preventing said digital chrominance signal (130) to pass therethrough when said color killer signal (137) appears; and subtractor means (402, 423, 425) coupled to said killer gate means (421), for subtracting said gated signal (422) from a signal (424) corresponding to said digital video signal (110) to provide a signal (131) corresponding to said digital luminance signal (133).

Claim 15

A digital television receiver for digitizing an analog video signal (101) and processing a digital video signal (110), characterized by comprising: separator means (126, 128) for separating a chrominance signal (130) and a luminance signal (131) of the digital video signal (l10); and color killer means (135) for setting the chrominance signal (130) to be substantially zero when an amplitude of a color burst of the chrominance signal (130) from said separator means (128) has lower level than a predetermined level, and for supplying a color killer signal (137) indicating to said separator means (128) whether or not color killer operation is performed, said separator means (128) being arranged to generate the digital video signal (110) as the luminance signal (131) in a color killer mode.

Claim 16

A digital television receiver for digitizing an analog video signal (101) and processing a digital video signal (110), characterized by comprising: separator means (126, 128) for separating a chrominance signal (130) and a luminance signal (131) of the digital video signal (l10); and color killer means (135) for setting the chrominance signal (130) to be substantially zero when an amplitude of a color burst of the chrominance signal (130) from said separator means (128) has lower level than a predetermined level, and for supplying a color killer signal (137) indicating to said separator means (128) whether or not color killer operation is performed, said separator means (128) being arranged to generate the digital video signal (110) as the luminance signal (131) in a color killer mode.

Claim 17

A receiver according to claim 14, characterized in that said separator means (126 to 129) includes: a chrominance signal separator for separating the chrominance signal (130) from the digital video signal (110); a subtractor (425) for subtracting the chrominance signal (130 or 422) from the digital video signal (110 or 424) to obtain the luminance signal (131); and a gate (421) inserted in an input side of said subtractor (425), which sets the chrominance signal (130) supplied to said subtractor (425) to zero when the color killer signal (137) indicates the color killer mode.

Claim 18

A receiver according to any one of claims 1 to 6, characterized in that said signal separator means (126 to 129) includes: comb filter means (401, 423) for filtering said digital video signal (110) with a first frequency characteristic H comb (f) and generating a first signal (410) and a second signal (424); band-pass filter means (412) coupled to said comb filter means (401), for filtering said first signal (410) with a second frequency characteristic H BPF (f) and generating a third signal (419); switch means (420, 421) coupled to said band-pass filter means (412) and being responsive to an NTSC/PAL switch signal (146), for generating from said third signal (419) a fourth signal (422) with an NTSC filtering characteristic H comb (f)·H BPF (f) when said NTSC/PAL switch signal (146) indicates an NTSC mode, and generating from said third signal (419) a fifth signal (422) with a PAL filtering characteristic 2H comb (f)·H BPF (f) when said NTSC/PAL switch signal (146) indicates a PAL mode; and composition means (425, 129) coupled to said comb filter means (423) and to said switch means (421), for composing said fourth signal (422) and said second signal (424) with an NTSC signal separation characteristic HY(f)N: H Y (f) N = 1 - H comb (f)· BPF (f) and composing said fifth signal (422) and said second signal (424) with a PAL signal separation characteristic Hy(f)p: H Y (f) P = 1 - 2·H comb (f)·H BPF (f) that said composition means (425, 129) generates said digital luminance signal (133) according to said NTSC signal separation characteristic H Y (f) N when said NTSC/PAL switch signal (146) indicates said NTSC mode, and generates said digital luminance signal (133) according to said PAL signal separation characteristic H Y (f) P when said NTSC/PAL switch signal (146) indicates said PAL mode, that said first frequency characteristic H comb (f) is defined as: where n denotes a natural number and f H denotes a horizontal frequency of NTSC or PAL system, and that said second frequency characteristic H BPF ( f ) is defined as: where f sc denotes a chrominance subcarrier frequency of NTSC or PAL system.