JPS6028396A - Video signal transmission system - Google Patents

Abstract

PURPOSE:To attain the video signal transmission of a component system at a narrow band by applying time axis compression to the 1st color difference signal, the 2nd color difference signal and the low frequency component of a luminance signal at a position not overlapped timewise, transmitting them and applying a specific operation. CONSTITUTION:A composite video signal is fed to a separating circuit 2 for separating a luminance signal Y and a chrominance signal C, and the low frequency component YL and color difference signals R-Y, B-Y are fed to a time axis compression circuit 5 comprising a CCD or the like. The low frequency component YL of the luminance signal is shared to CCDs 92, 93 at each horizontal period by a changeover switch 91 and the color difference signals R-Y and B-Y are shared respectively to CCDs 95R, 96R, 95B and 96B by changeover switches 94R, 94B similarly. The signals are selected by a changeover switch 99 in a prescribed timing and a time division signal is formed. A signal Y'H from a delay circuit 12 and a signal from the time axis compressing circuit 5 are synthesized by a synthesis circuit 13. The missing high frequency component due to the time axis compression is transmitted by synthesizing the high frequency components of the luminance signal and transmitting them while synthesizing them with frequency interleaving.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal transmission system suitable for use in so-called component 1 type video tape recorders (VTRs) and the like.

BACKGROUND ART AND PROBLEMS Video signal transmission systems are broadly classified into two types: combo shift system and component system. Of these, combojiso{・
The method modulates the chroma signal and multiplexes it within the band of the luminance signal, and is compatible with NTSC and PAL.

Television systems such as SRCAM correspond to this,
While it is possible to transmit chroma signals and brightness signals in a narrow band,
It is difficult to completely separate the chroma signal and luminance signal during demodulation,
Image quality deterioration such as dot interference and cross color is likely to occur.

On the other hand, the component method transmits the luminance signal and chrominance signal independently, making it difficult to accurately separate the luminance signal and chrominance signal, but it has a slightly wider band than the combo shift method. It has some necessary drawbacks.

OBJECTS OF THE INVENTION In view of these points, the present invention devises a component-based video signal transmission system that is capable of recording and reproducing OJ in a narrow band, especially in a home VTR.

SUMMARY OF THE INVENTION The present invention provides that a first color difference signal, a second color difference signal, and a low frequency component of a luminance signal are compressed in time and transmitted at a position where they do not overlap in time, and that the high frequency component of the luminance signal is A video signal transmission method characterized in that low frequency components of the first and second color difference signals and the luminance signal are frequency interleaved and transmitted without being subjected to time axis compression, According to the method, component-based video signal transmission can be performed in a narrow band.

Embodiment In FIG. 1, a composite video signal as shown in FIG. 2A is supplied to the input terminal (1).

This signal is the luminance signal Y and chroma signal C separation circuit (2)
A luminance signal Y and a chroma signal C as shown in FIG. 2B are separated. Furthermore, this chroma signal C is supplied to a demodulation circuit (3), and two color difference signals RY and 13-Y are taken out as shown in FIG. 2C and D. Further, the luminance signal Y is supplied to a low-pass filter (4), and a low-frequency component YL below the frequency fP shown by the broken line in FIG. 2B is extracted. These low-frequency component YL% color difference signals R-Y and B-Y are supplied to a time axis compressed signal 9 (51) constituted by a CCD or the like.

In addition, the signal from the input terminal (1) is transmitted to the synchronous branch 11 circuit (6
) to separate the synchronization signal, and this synchronization signal is supplied to P
The signal is supplied to L L (71) to form a desired multiplied signal. This signal from P L L (71) drives the time axis compression circuit (5).

The low frequency component YL of the Zunawaji luminance signal is set using the selector switch (91
) for each horizontal period (92).

(93), and the color difference signals R-Y and B-Y are also changed to C0D (951), (961?), (95B) by changeover switches (94R) and (94B), respectively.
, (96B). These CCDs (92
), (93).

(951?) , (96R) , (95B) , (96
B) is driven at a frequency corresponding to each pixel of the video signal during reading, and is driven at a frequency corresponding to each pixel of the video signal during readout.
).

(96R) is n7m times the time of publication (Ishi2n<m
), COD (95B), (96B) are n/
n/m times from the late rnn sluice period, CCD (
92) and (!J3) are driven at a frequency (12n)/m times higher than the time point delayed by 2n/m horizontal period. This results in Figure 3A, respectively.

Writing is performed on B, C, D, E, and F as shown by solid lines, and color difference signals (R-Y)', (B-Y) whose time axis is compressed by ri/m times as shown by broken lines, respectively. ' and (1
The low frequency component Y'L whose time axis has been compressed by a factor of 2n)/m is read out.

The signals from these CCDs (92) and (93) are taken out alternately every horizontal period by a changeover switch (97),
CD (95R), (9611), (95B),
The signal from (96B) is transferred to the selector switch (98R), (9
8B) are taken out alternately every horizontal period, and this signal is selected at a predetermined timing by a changeover switch (99) to form a time-division signal as shown in FIG. 3G.

Here, a luminance signal Y'L and a color difference signal (RY)'.

(B-Y)' are both compressed on the time axis, so that the frequency band is raised higher than that of the ordinary signal. The compression ratio n/m of time axis compression is determined so that the highest frequency of the increased color difference signals (R-Y)' and (B-Y)' becomes equal to the upper limit frequency fc of the transmission system band. The luminance signal Y'L enters the remainder of the time occupied by the luminance signal Y
' A compression ratio (1-2n) of 7m is determined. Also, with the low-pass filter, the cutoff frequency fP in 4) is fp =
fc X (1-2n) is defined as 7m.

Further, the luminance signal Y from the separation circuit (2) is supplied to a bypass filter (8) whose cutoff frequency is fP, and the second
l! of the luminance signal as shown in Figure F! JJ area component YH is extracted. This high-frequency component Y) (is supplied to the impark (9), and the phase-inverted signal and the signal 9 are supplied to the changeover switch 00). A signal Y'H whose phase is inverted every horizontal period from this switch 00 is supplied to the control terminal of this switch (101), which is inverted every horizontal period from PLL (71). 1
1), the horizontal and vertical blanking period signals are removed by the signal from PLL (71), and this signal yl is supplied to the delay circuit (12) for one horizontal period, and the time axis compression circuit The signal from (5) and tense are matched.

The signal Yl from the delay circuit (12) and the signal from the time axis compression circuit (5) are combined by a combining circuit (13).

As a result, the output terminal (14) of the combining circuit (13) receives the highest color difference signals R-Y and B-Y at the first half (n7m) and second half (n7m) of each horizontal period as shown in FIG. 2F and G, respectively. The time axis is compressed so that the frequency is equal to the upper limit frequency 1'C of the transmission system, and a synthesized signal in which the high frequency component Y'H is frequency interleaved is provided.
2n)/m, as shown in Figure 2H, is a signal provided with a composite signal in which the high frequency component Y'+ is frequency interleaved with the low frequency component Y'L whose time axis is compressed by (12n)/m times. is taken out.

This signal is recorded (transmitted) by, for example, a home VTR.

Further, FIG. 4 shows a circuit for demodulating the signals recorded in this manner. In the figure, the input terminal (15)
is supplied with the signal obtained at the above-mentioned terminal (14).

This signal is supplied to a bypass filter (16) and a low-pass filter (30) to separate the band in which the above-mentioned high frequency component Y\1 is synthesized and the bands below it.

The signal (YH) from this bypass filter (16) is 1
The high-frequency component Y' is supplied to a comb filter consisting of a horizontal period delay circuit (17), a subtraction circuit (18), and an addition circuit (19), and whose phase is inverted every horizontal period from the subtraction circuit (]8). At the same time, the addition circuit (19) outputs the time-axis compressed low frequency component Y', and outputs the color difference signal (R-Y
)', (BY)' high frequency components are extracted. This time-axis compressed low frequency component Y'L, color difference signal (R-Y)',
(B-Y)' high frequency component and low pass filter (30)
Similarly, the low-frequency components from the above are supplied to a synthesis circuit (20), the above-mentioned time-base compressed signal is extracted, and this signal is supplied to a time-base expansion circuit (21).

In addition, the signal from the terminal (15) is transmitted to the same Jtl1 separation circuit (2
2) to the PLL (23), and this P L
The multiplied signal from L (23) is supplied to the time axis expansion circuit (21). The time axis expansion circuit (21) performs an operation opposite to that of the time axis compression circuit (5), and extracts the low frequency component YL of the luminance signal and the color difference signals RY and BY.

Further, the signal Y+ from the lIi arithmetic circuit (18) is supplied to the +input node (24), and the phase is inverted (No. 3 and the original signal are switched and supplied to the switch (25) & , this changeover switch (25) is switched every horizontal period of the signal from the PLL (23) to display the original brightness signal Y.
The high-frequency component YH is extracted, and the high-frequency component YH and the low-frequency component Y from the time axis expansion circuit (21) are combined in the synthesis circuit (27) to form a luminance signal Y<( It will be held in summer at 11M.

In this way, the luminance signal Y9 and the color difference signal R-Y.

B-Y is demodulated. And these signal powers < (+
If it is supplied to the matrix circuit (28), R, G,
Three primary color signals of B are formed and these signal powers are fed to a color cathode ray tube (29) to produce a color image power.

This is how video signals are transmitted, right?
According to the above-mentioned device, the luminance signal and the color difference signal are transmitted independently in a component manner, so that these signals can be separated easily and accurately, and they can be compressed in their respective time bases. By transmitting in hours/minutes ml), it can also be applied to narrow band transmission systems such as home VTRs.

In addition, the high frequency component of the luminance signal is placed in the frequency inter 1 node.
By not transmitting ζ-synthesis, it is possible to transmit high-frequency components that are lost due to time-base compression of the luminance signal, and the luminance signal band can be widened, allowing for high-quality image transmission. became possible.

By the way, in the above-mentioned device, when the high frequency component YH is transmitted as it is by frequency interleaving, the liquid crystal frequency of this high frequency component Y) is limited by the highest frequency fC of the transmission system, and the iG+ region is necessarily 4) Not transmitting enough.

Therefore, in FIG. 5, it is possible to transmit even higher frequency components of this luminance signal Y.

In the figure, a band-pass filter (31) is provided in place of the band-pass filter (8) in FIG. This multiplier circuit (32) is supplied with 4 P
A continuous signal of frequency fx is supplied from L L (71) and the high frequency component YH is converted to a low frequency.

Here, the frequency fX may be equal to the frequency fP mentioned above, and further fx=K・□ (however, fH is the half frequency of water)
By doing so, this low frequency converted signal Y becomes a frequency interleaved signal.

And this low frequency converted signal Y negative is sent to the switch (11)
, are supplied to the synthesis circuit (13) through the delay circuit (12). The rest is the same as in FIG.

In other words, the high frequency component Y of the luminance signal Y as shown in FIG. 6A
H (equivalent to FIG. 2E) is low-pass converted as shown in FIG. 6B. This low-frequency converted signal Y¥1 is a frequency interleaved signal, so this signal Y has a time-axis compressed low-frequency component Y'L, color difference signal Jff(RY)', (B-
Y)' are synthesized as shown in Figure 6 C, D, and E.

Furthermore, FIG. 7 shows a demodulator, in which a low frequency conversion signal Y'H is taken out from a subtraction circuit (18), this signal is supplied to a multiplication circuit (33), and a PLL (
23) is supplied with a continuous signal of frequency fX, and the low frequency conversion signal Y is inversely converted.

This inversely converted signal YH is supplied to an adder circuit (27) through a delay circuit (26) to form the original luminance signal Y. The rest is the same as in FIG.

Therefore, according to this configuration G, the luminance signal Y can be transmitted to a higher frequency range, and at this time, the band of the transmitted signal does not become wider.

In Fig. 5, the bandpass filter (31) is used to separate the high-frequency component Y)l because the low-frequency converted signal Y
This is to prevent crosstalk from occurring since the effect of frequency interleaving will be lost if i extends to too low a frequency range.

Effects of the Invention According to the present invention, component-based video signal transmission can now be performed in a narrow band.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of one example of the present invention, Figs. 2 to 4 are for explanation thereof, Fig. 5 is a block diagram of another example, and Figs. 6 and 7 are for explanation thereof. This is a diagram. (1) is the input terminal, (2) is the luminance chroma separation circuit, (3
) is color fit) 1 circuit, (4) is low pass filter, (
5) is a time i1i+11 compression circuit, (6) is a synchronous separation circuit, (7) is a PLL, (8) is a bypass filter, (9
) is an inverter, and (14) is an output terminal.

Claims (1)

[Claims] 1, f! The S1 color difference signal, the second color difference signal, and the low frequency component of the luminance signal are time-axis compressed and transmitted at positions that do not overlap in time, and the surface frequency component of the luminance signal is not time-axis compressed. A video signal transmission system characterized in that low frequency components of the first and second color difference signals and the luminance signal are frequency interleaved and transmitted. 2. The video signal transmission system according to item 1 of the patent, wherein the high frequency component of the luminance signal is frequency shifted to the lower frequency side.