Patent GB-1487406-A (GB)
Title: Video recorders and receivers
IPC: H04N5/775
Filed: 1974-10-04
Abstract: 1487406 Colour television MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 4 Oct 1974 43256/74 Heading H4F A colour television receiver and a magnetic tape recorder/reproducer are combined in one apparatus, certain of the circuits in such apparatus being used in common in the receiver section and recorder/reproducer section. In a first embodiment, Fig. 4, a switch SW 3  closes contact P 1  during reception or recording, the output of video detector 3 being supplied to synchronization signal separator 16, luminance component processing circuits 4, 5, 6, and chrominance component processing circuits 7, 8, 13, the outputs of video amplifier 6 and chrominance demodulator 13 being fed via a matrix circuit 14 to a picture tube 15. Band-pass amplifier 7 is controlled by an automatic chroma control circuit 11 which receives a control signal from an automatic phase control circuit 10 which also controls chrominance demodulator 13 and colour killer 12 connected to bandpass amplifier 8. The luminance component is also supplied from low-pass filter 5, or video amplifier 6, to a frequency modulator 25 via a pre-emphasis circuit 24, and the chrominance component is supplied from band-pass amplifier 8 to a balanced modulator 31 at which it is frequency converted to have a frequency band lower than the frequency-modulated luminance component to which it is added at 34, the added signal being recorded at 36. During playback switch SW 3  closes contact P 2  and connects the output of an adder 53 to circuits 16, 4 and 7. One input of adder 53 is the demodulated luminance component from 39 and the other input is the chrominance component of the original frequency band and free from jitter derived from a balanced modulator 51 receiving a reference signal from a variable frequency oscillator 57 controlled by a horizontal synchronization frequency detector 50 and a phase comparator 56. In an alternative embodiment (Fig. 8, not shown) adder 53 is omitted, the output of video detector 3 being supplied to delay circuit 4 and to one input terminal of a switch (SW 4 ), the other switch input terminal being directly connected to the output of balanced modulator 51 and the output terminal of the switch being connected to the band-pass amplifier 7. A second, ganged, switch (SW 5 ) is included between low-pass filter 5 and video amplifier 6 to supply to the video amplifier 6 either the output of low-pass filter 5 or the output of de-emphasis circuit 40. In an alternative form of either of these embodiments (Figs. 11, 12, not shown) the variable frequency oscillator 57 is omitted and balanced modulator 51 is replaced by a balanced modulator (43) receiving, as reference input, the output of crystal oscillator 32, jitter being removed by circuits 9-13. In a further embodiment (Fig. 10, not shown) switch SW 3  is connected as shown in Fig. 4, the balanced modulator (43) similar to balanced modulator 51 receives as reference input the output of crystal oscillator 32, and there are included separate automatic phase control circuits 10, (70) for operation during recording and reproduction respectively, three additional switches being included to connect the respective automatic phase control circuits to the automatic chroma control circuit 11, the colour killer 12, and the chrominance demodulator 13.