Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1985-07-18
1987-06-09
Groody, James J.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358 11, 358141, H04N 701
Patent
active
046724460
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a television receiver which displays a television picture at, for example, a field frequency twice the normal field frequency.
BACKGROUND ART
In the existing television system, a so-called interlaced scanning system is carried out. That is, one picture (frame) is transmitted by two vertical scannings (fields). This interlaced scanning system is considered in order to increase the number of scanning lines as much as possible in a limited frequency band without a flicker being perceived by a viewer.
However, in the CCIR system employed mainly in European countries, the field frequency is 50 Hz. By this frequency, the flicker can not be removed completely and the flicker becomes conspicuous particularly when the brightness of the television picture is high.
Therefore, in the prior art, such a television receiver is proposed that a television picture is displayed at a field frequency twice the normal field frequency. FIG. 1 shows an example thereof.
In the figure, reference numeral 1 designates an antenna, 2 a tuner, 3 a video intermediate frequency amplifier, and 4 a video detecting circuit. The video detecting circuit 4 produces a video signal Sv of the interlaced system of, for example, 625 lines/50 fields and 2:1.
This video signal Sv is converted to a digital signal by an A/D converter 5 and then fed to a converting circuit 6 so as to be converted to a field twice normal speed video signal with the field frequency twice the normal field frequency.
The converting circuit 6 is formed of field memories (random access memories each having a storage capacity sufficient for the picture elements of one field period (1V)) 6a and 6b and switching circuits 6c and 6d. The switching circuit 6c is changed in position to the sides of the memories 6a and 6b at every field period 1V, while the switching circuit 6d is changed in position reversely. The memory selected by the switching circuit 6c is supplied with a write clock pulse having a timing corresponding to the above-described picture elements, while the memory selected by the switching circuit 6d is supplied with a read clock pulse with the frequency twice the frequency of the write clock pulse.
The video signal Sv converted to the digital signal by the A/D converter 5 is supplied through the switching circuit 6c to the memories 6a and 6b by one field each at every field period 1V in which it is written. The video signal of one field amount, which is written in the memories 6b and 6a during a field period 1V just before the above-mentioned field period, is read out therefrom continuously twice with a cycle of 1/2V. This video signal is derived through the switching circuit 6d. In other words, the switching circuit 6d delivers a field twice normal speed video signal Sv' with the field frequency.
This video signal Sv' is converted to an analog signal by a D/A converter 7 and then fed to a signal processing circuit 8. Then, from the signal processing circuit 8, red, green and blue primary color signals R, G and B are produced and then supplied to an image receiving tube 9, respectively.
The video signal Sv derived from the video detecting circuit 4 is supplied to a vertical synchronizing separating circuit 10. A vertical synchronizing signal Pv derived from the separating circuit 10 is multiplied twice by a frequency multiplyer 11 to be a signal with the frequency twice the ordinary frequency. This signal is supplied through a vertical deflecting circuit 12 to a deflecting coil 13.
The video signal Sv' derived from the D/A converter 7 is supplied to a horizontal synchronizing separating circuit 14. A horizontal synchronizing signal P.sub.H ' (having the frequency twice the normal frequency) derived from the separating circuit 14 is supplied through a horizontal deflecting circuit 15 to the deflecting coil 13.
Since the example of the television receiver shown in FIG. 1 is constructed as described above, the primary color signals R, G and B each of which has the field frequency twice the normal field frequency are s
REFERENCES:
patent: 4364090 (1982-12-01), Wendland
patent: 4451848 (1984-05-01), Okada et al.
Ikeda Yasunari
Nakano Hiroshi
Yuchi Hirofumi
Eslinger Lewis H.
Groody James J.
Parker Michael D.
Sinderbrand Alvin
Sony Corporation
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