JPS6018089A - Video signal recorder - Google Patents

Abstract

PURPOSE:To eliminate a timing shift between the luminance and color signals by setting an equal compression ratio of time axis between a horizontal synchronizing signal and the luminance signal and using clock signals of different frequencies to perform the time compression of both the luminance and color signals. CONSTITUTION:A video signal generating part 10 produces two color difference signals U and V as well as a luminance signal Y for a device which gives the time division multiplexing to both the luminance and chroma signals in a video signal through a multiplexing circuit 1 and then supplies these multiplex signals to recording parts 2-9. These signals U, V and Y are compressed by time compression circuits 20-23 and selected by a switch 30 after undergoing selection by changeover switches 24 and 25 and then addition/subtraction with prescribed signals through a subtractor circuit 28 and an adder circuit 29. In other words, the signals of the circuit 29 are delivered in periods t1-t3 and t8; the signals of the switch 25 are delivered in periods t5 and t6; and the signals of the circuit 28 are delivered in a period t7 respectively. A time compressing clock signal generating circuits 11-15 supply the 1,152-fold reading clock and 384- fold writing clock as much as the horizontal synchronizing frequency fH to compression circuits 20-23 respectively.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device for recording video signals on a magnetic medium, and particularly to a device suitable for time-division multiplexing and recording of luminance signals and chroma signals in a video signal. Regarding.

[Background of the invention]

In the conventional technology of time-division multiplexing the luminance signal and the a-ma signal for recording and reproducing, it is necessary to make the horizontal blanking period extremely short.
This causes deterioration and makes it difficult to restore the time-compressed 'IN''r using the horizontal synchronization signal as a reference.

[Purpose of the invention]

The purpose of the present invention is to reduce the influence of waveform distortion and noise received in the transmission system, and to prevent horizontal fluctuation of the reproduced image and timing deviation between the luminance signal and the chroma signal.
An object of the present invention is to provide a device for recording M numbers by time division multiplexing.

[Summary of the invention]

Alternatively, in the present invention, the time compression ratio of the luminance signal and the horizontal synchronization (ij number) with respect to the original signal are set to be equal, and the time compression ratio of the real time signal is set to be more than twice the compression ratio of the luminance signal, The clock signals for converting the time axes of the chroma signal and the luminance signal are made into signals whose phases are synchronized with each other.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained using FIGS. 1 to 4. FIG. 1 is a diagram showing an embodiment of a time division multiplexed signal waveform according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the magnetic recording device of the present invention including a circuit that generates the signal waveform of FIG. 1A. It is a diagram. All of the embodiments will be described using the present invention in a two-head helical scan video tape recorder.

In Fig. 2, 1 is a time division multiplex signal generation circuit, 2 is a synchronous peak Flang circuit, 3 is a dynamic emphasis 1 envelope in which the emphasis amount becomes thicker as the amplitude of the input signal is smaller, 4 is a Klinip circuit, and 5 is a Klinip circuit. frequency modulation circuit,
6 is Nagi, a built-in amplifier, 7 is a rotary transformer, 8 is a video head, and 9 is a video chip.

10 is a video signal generation circuit, which is designated by Y in FIG.

Outputs U and V component signals. U.

V indicates two color difference signals B-Y, R-Y@11 to 1
Reference numeral 5 designates a time compression clock signal generation circuit, which is composed of a PLL consisting of a synchronous separation circuit 111, a phase comparator 12, a VCO 11-13, a τ frequency divider, and a frequency divider 15.

16, 17, and 18 convert analog signals into digital signals. Le Φ converter, 19 converts the tental signal by approximately 1
H (one horizontal scanning period, 63.556 in NTSC system)
ps, 64μ with CC1,R method? ) The delay circuits 20, 21, 22, and 23 are time compression circuits that compress the time axis rapidly. Time compression circuit 20゜2
The write clock for 1.22.26 is the output of frequency divider 14.
Me number TE N T SC method is 15.754 ulz
, 15,625 KHz) is used in the CCI R system, and 1152jH, which is the output of the VCO 13, is used as the read clock.

24 is a signal changeover switch, and tl in FIG.
During the period of s t2 * tR+ '8, the delay circuit 19
During the period t7, the time pressure n own circuit 2 is output.
Outputs an o signal.

25 is a No. 4g changeover switch, and t in Fig. 1A
, the signal from the time compression circuit 21 is output during the period t
During the period t, the signal from the time compression circuit 23 is output, and
During period 7, the signal from the time compression circuit 22 is output.

26 and 27 are Dy for converting digital signals to analog signals.
It is a converter. 28 is a subtraction circuit that outputs (Yn-1Yn)/2 in Figure 1A. 129 is an addition circuit that outputs (Yn-1 + Y7L in Figure 1A)
)/2 is output.

30 is a signal changeover switch, which outputs the signal from the adder circuit 29 during the '1 m '2 + tRe t80 period in the first LWl, and outputs the signal from the D/A converter 26 during the period 4 * t6. A signal is output from the subtraction circuit 28 during the period t7.

1 at t4 in FIG. 1A is the zero level of the color difference signal. Since ts + t4 during t1, it is possible to determine whether the line is a sum signal line or a difference signal line by looking at the length of the back porch.

If To-41, 2fH, t, = t8 = 207To, t, = 945T0.
tR−=1877′o, t.

= 20T(,, t, -t6 = t, = 5i 5T
No. 11 can be restored by setting the write clock to 1152ji and the read clock to 384j'y during playback. Y.

The starting position of each signal of U's V is determined based on the leading edge or trailing edge of the horizontal synchronizing signal. The leading edge is influenced by the image content immediately before the front porch, so it is desirable to use the trailing edge as a reference.

FIG. 3 is a block diagram showing an embodiment of the magnetic recording apparatus of the present invention including a circuit for generating the signals B and C (IJ) shown in FIG.

In FIG. 3, 31 to 36 are time compression clock signal generation circuits, including a phase comparator 31, V6O13, -! −
Frequency divider 33.1 Frequency divider 34. ” - Frequency divider 65° 3 4
It is composed of a pLL consisting of a 256.1 frequency divider 36.

37 and 38 are 7-time compression circuits, which use 256fH, which is the output signal of the frequency divider 64, as a convolution clock.

1556fK, which is one word output from the frequency divider 36, is read out and set to 0. 59 is a 7-time compression circuit, which converts the output signal of the frequency divider 56, 1024fII, to 1. The input clock is +1556fxy read clock.

40 is a No. 4g changeover switch, and t in Fig. 1B
During the period o, No. 1i is output from the time compression circuit 5B,
The signal from the time compression circuit 67 is output during the '100 period, and the signal from the time compression circuit 39 is output during the tll period. 41 is a D/A converter, 42 is a signal changeover switch, and tI * tl * t in FIG. 1B.
During the period 3 + t8, the signal from the video signal generation circuit 10 is output, and during the period t9 + '10*tll, the signal from the iA converter 41 is output.

Next, the case where 1 in FIG. 3 outputs C in FIG. 1 will be explained. The switch 40 is tl2 s in FIG.
During the period tl6 * '17 + t21 * '22, the signal from the time compression circuit 39 is output, and the signal from the time compression circuit 39 is output during the period tl4 +
During the period tIQ, the signal from the time compression circuit 38 is output, and during the period tl511?00, the signal 1g from the time compression circuit 67 is output.

” = 1536f JF, then in Figure 1B “'Ct, = t, = 276T, .
t2=1260T.

t3=256T, t4=20T1. t, -l,
. = 2101□, tl, ==840T.

In Figure 1C -tIt = tIT = t22
= 184'11t13 "tl8 =tt3 ""
92TI j tl4-tl5 = '10 ""2
0 = 210T, , t, , = t, , =, 84
0T, it's true.

FIG. 4 is a block diagram showing an embodiment of the magnetic recording apparatus of the present invention including a circuit for generating the signals shown in the first diagram. Fourth
In the figure, 31, 32.35, 36, 43, and 44 are time compression clock signal generation circuits, 44 is a one frequency divider, and 44 is a times frequency divider.

Reference numeral 45 denotes an official code changeover switch, which alternately outputs U and V for each line. 46 is an A/D converter, 47 is a 7-hour compression circuit, and the input a is set to 512 fH.
The read clock is set to 1556ftr. 48 is a signal changeover switch, and t1□I in the first ID
'161 t25 S t2□+ t2□ period fl'
At t241, a signal from the time compression circuit 39 is output.
During the period t27, the signal from the time compression circuit 47 is output.

In the first diagram, t1□=t22-18410,1I
3-t23 = 92 stones + t24 "" tl! ? ”'
420Tl tl6 ””2J2840T,.

i2. -246T1. t26=soT□.

〔Effect of the invention〕

According to the present invention, it is possible to completely eliminate the horizontal fluctuation of the image and the timing deviation between the N-degree signal and the chroma (g-degree), which are the drawbacks of the conventional time-division multiplexing method.

[Brief explanation of the drawing]

Figure 1 shows an example of a time division multiplexed signal used in the present invention.
The f signal waveform diagrams, FIGS. 2, 3, and 4 are block diagrams showing one embodiment of the magnetic recording apparatus of the present invention. 1... Time division pot M signal recessive circuit 12, 31... Phase comparator 13, 32... VCO 20, 21, 22, 23, 57, 3B, 39, 4
7...Time compression circuit

Claims (1)

[Claims] In a device that records a signal obtained by time-division multiplexing of a luminance signal and a color signal on a recording medium, the time axis compression ratio of the horizontal synchronization 4W signal and the luminance signal is the same, and the difference between multiple frequencies that are phase-synchronized with each other is a 1. A video signal recording device characterized in that a luminance signal and a chrominance signal are time-compressed by using a chrominance signal.