JP2611280B2 - Recording and playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus having a time axis error correction function, and more specifically, to prevent a time axis error of a luminance signal from being accumulated even during dubbing. And a recording / reproducing apparatus.

[Conventional technology and its problems]

In a magnetic recording / reproducing device, the output of the magnetic head includes a time axis error due to uneven rotation of the magnetic head and fluctuations of the tape running speed. Therefore, there is provided a time axis error correction circuit for correcting a video signal with a correct time axis. However, since it is not necessary to correct the time axis error for the luminance signal, a reproducing apparatus that corrects the time axis error only for the color signal is generally commercially available.

A video signal reproduced and output from such a reproducing apparatus is
Although the color signal component does not include a time-axis error, the luminance signal component includes a time-axis error. For example, when dubbing is performed, a luminance signal that originally includes a time-axis error is recorded on a copy destination magnetic tape. become. When the dubbed magnetic tape is reproduced, a time axis error occurs again, so that the time axis error is accumulated, and this causes a significant deterioration in image quality.

Therefore, an object of the present invention is to provide a recording / reproducing apparatus which overcomes this problem.

[Means for solving the problem]

The recording / reproducing apparatus according to the present invention includes a correction unit that corrects a time axis of a composite video signal obtained by multiplexing a luminance signal and a chrominance signal, and a composite video signal obtained by multiplexing a luminance signal and a chrominance signal. Recording processing means for converting into a suitable format color video signal, recording means for recording the color video signal from the recording processing means on a recording medium,
Reproducing means for reproducing a color video signal from the recording medium; and reproducing processing means for converting the reproduced color video signal into a composite video signal of an original format. During recording, the correction means inputs the composite video signal. Is corrected, the composite video signal from the correction means is output to the recording processing means, and at the time of reproduction, the time axis of the reproduced color video signal is corrected by the correction means. A color video signal is output to the reproduction processing means.

[Action]

By the above means, at the time of recording, the time axis error of the input composite video signal is corrected before recording on the recording medium, and at the time of reproduction, the time axis error of the reproduced signal is corrected before the reproduction processing. Therefore, even if the input composite video signal includes a time axis error, a video signal from which the time axis error has been removed is recorded on the recording medium. Also, at the time of reproduction, since the time axis error is corrected before the reproduction processing, the characteristics of the reproduction signal processing are improved, and even if dubbing is repeated, the image quality does not significantly deteriorate.

Since the time axis correction means is used for both recording and reproduction, recording performance and reproduction performance can be improved at low cost.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a recording system according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of a reproducing system.
Note that Y is a luminance signal, C is a chrominance signal, f _SC is a carrier color signal or its frequency, f _LSC is a low-band carrier color signal or its frequency, f _H
Indicates a horizontal synchronizing signal or its frequency, and those suffixed with “ ^* ” after these signals indicate that a time axis error is included.

The recording system of FIG. 1 will be described. A video signal output from a conventional reproducing apparatus, that is, a luminance signal Y ^* including a time axis error and a carrier chrominance signal f including no time axis error are input to an input terminal 10.
It is assumed that a video signal composed of _SC is input. Numeral 40 denotes a time axis correction circuit, which will be described in detail later. The CCD 42 as a variable delay element corrects the time axis error of Y ^* , and the carrier chrominance signal C has the same magnitude with the opposite direction in which the error occurs. Is added and output.

The output of the time axis correction circuit 40 is separated into a luminance signal Y and a carrier chrominance signal C ^* (or f _SC ^* ) by the Y / C separation circuit 12, and the Y signal is FM-modulated by the FM modulation circuit 14 and applied to the adder 16. Is done. The carrier chrominance signal f _SC ^* is applied to the multiplier 18, to which a carrier (f _SC ^* + f _LSC ) reflecting the time axis error of the input Y ^* is applied, as described below. Therefore, the multiplier 18 outputs the low-frequency carrier chrominance signal f _LSC that does not include the time axis error. The adder 16 adds and superimposes the FM-modulated luminance signal Y from the FM modulation circuit 14 and the low-frequency carrier chrominance signal f _LSC from the multiplier 18, and outputs the output of the adder 16 via the recording amplifier 20. The voltage is applied to the recording head 22 and recorded on the magnetic tape 24.
That is, the magnetic tape 24 is recorded with the time axis error of the input video signal corrected.

The phase comparator 26, the VCO 28, and the frequency divider 30 form a PLL circuit. That is, the phase comparator circuit 26, a horizontal synchronization signal f _H without the time base error extracted from the luminance signal separated by the Y / C separation circuit 12, and an output of the frequency divider 30 to the phase comparator, the phase difference Apply signal to VCO 28. VCO 28 oscillates at a frequency 378F _H in accordance with the phase difference signal, the frequency divider 30 is the output of the VCO 28 1/37
The frequency is divided by 8 and fed back to the phase comparison circuit 26. After all, the output of VCO28 does not include the time axis error,
The frequency is _divided by 1/8 to form a carrier of frequency f _LSC . The phase comparison circuit 34 and the VXO 36 also constitute a PLL circuit, and the phase comparison circuit
34 compares the phase of the carrier chrominance signal f _SC ^* from the Y / C separation circuit 12 with the output of the VXO 36. VXO36 outputs the synchronization signal (for convenience of explanation, it referred to as f _SC ^*) in the carrier chrominance signal f _SC ^*.
The multiplier 38 multiplies the carrier f _SC ^* from the VXO 36 by the carrier f _LSC from the frequency divider 32, outputs a carrier (f _SC ^* + f _LSC ), and applies the carrier (f _SC ^* + f _LSC ) to the multiplier 18. As a result, the multiplier 18 outputs the low-frequency carrier chrominance signal f _LSC that does not include a time-axis error as described above.

Next, the operation of the time axis correction circuit 40 will be described. PLL circuit 4
1 is a PLL comprising a phase comparison circuit 26, a VCO 28 and a frequency divider 30
This is a circuit similar to the circuit, and extracts the horizontal synchronization signal from the luminance signal including the time axis error of the input terminal 10 and has a frequency of 378f.
Output carrier including time axis error by _H. Divider 44 is P
The output of the LL circuit 43 is divided by 1 / N. Phase comparison circuit 46, LPF4
8, the VCO 50 and the 1 / N frequency divider 52 constitute a PLL circuit. That is, the phase comparison circuit 46 compares the phase of the carrier (including the time axis error) output from the frequency divider 44 with the carrier from the frequency divider 52, and controls the VCO 50 via the LPF 48 based on the phase error signal. Apply to input. VCO50 oscillates at a frequency 378f _H, and applies the output to the frequency divider 52. The output of the phase comparator 46 includes the time axis error of the input luminance signal, and the VCO
Applied to 56 control inputs. Therefore, the frequency of the clock output from the VCO 56 also includes a time axis error. CCD4
2 acts on the input multiplexed signal (Y ^* + f _SC ) in a direction to cancel the time axis error of Y ^* under the control by the clock. That is, the time axis error is corrected for the luminance signal by the time axis correction circuit 40, while the carrier chrominance signal includes a time axis error in which the error occurs in the opposite direction.

A brief description will be given of a case where a video signal containing no time axis error is input to the input terminal 10.In this case, the PLL circuit 4
The output of No. 3 does not include a time axis error, and therefore, the time axis correction circuit 40 merely provides a fixed time delay to the luminance signal and the carrier chrominance signal of the input video signal. Therefore, the time axis error of the luminance signal and the carrier chrominance signal output from the Y / C separation circuit 12 is not included, and the signals input to the phase comparison circuits 26 and 34 do not include the time axis error. Therefore, the signal recorded on the magnetic tape 24 does not include the time axis error.

Next, the reproduction system shown in FIG. 2 will be described. 60 is magnetic tape, 62
Is a reproducing head, and 64 is a reproducing amplifier. The output of the reproduction amplifier 64 is a video signal (Y ^* + f _LSC ^* ) including a time axis error. The time axis correction circuit 66 is the time axis correction circuit 40 shown in FIG.
It has exactly the same configuration as. However, a clock including a time axis error is input from an AFC / APC circuit described later. The time axis fluctuation is removed from the output signal of the reproduction amplifier 64 by the CCD 42 of the time axis correction circuit 66. That is, the output of the time axis correction circuit 66 is (Y + f _LSC ). The Y / C separation circuit 70 outputs the luminance signal Y
And separated into a low-band carrier chrominance signal f _LSC, the luminance signal Y is demodulated by the FM demodulation circuit 72, are applied to the adder 74. Multiplier 76
Multiplies the separated low-frequency carrier chrominance signal f _LSC by a frequency (f _LSC + f _S ) formed based on the horizontal synchronization signal f _H extracted from the FM-demodulated luminance signal. The output of the multiplier 76 becomes the carrier chrominance signal f _SC , and the adder 74 multiplexes this with the FM-demodulated luminance signal and outputs it. The output of the adder 74 becomes a reproduced video signal.

AFC composed of phase comparison circuit 78, VCO 80 and frequency divider 82
The phase comparison circuit 78 of the circuit, a horizontal synchronization signal f _H extracted from the luminance signal demodulated by the FM demodulation circuit 72 (including. A time base error which can not be removed by the time base corrector 66) it is applied , A phase comparison circuit 84, a crystal oscillator 86 and
A color burst signal including a phase error is input to a phase comparison circuit 84 of an APC circuit composed of a VCO 80, and the VCO 80 outputs a clock including a time axis error to a frequency divider 82, a frequency divider 88, and a time axis correction circuit. The 66 divider 44 is supplied. The frequency division ratios of the frequency dividers 82 and 88 are 1/378 and 1/8, respectively. The multiplier 90 multiplies the carrier of the frequency f _SC from the crystal oscillator 90 by the output of the frequency divider 88, and outputs the carrier of the frequency (f _LSC + f _S ).

FIG. 3 is a basic block diagram of a recording / reproducing system in which the recording system of FIG. 1 and the reproducing system of FIG. 2 are combined. The same components as those in FIGS. 1 and 2 are denoted by the same reference numerals.
The switches 101, 102, 103, and 104 are connected to the R terminal side during recording, and are connected to the P terminal side during reproduction. As can be seen from the figure, the time axis correction circuits 40 and 66 and the magnetic heads 22 and 62 can be used for both recording and reproduction.

〔The invention's effect〕

As can be easily understood from the above description, according to the present invention, even when a video signal whose luminance signal includes a time axis error is input, the time axis error is corrected and recorded on a recording medium. Even if dubbing is repeated, time axis errors are not accumulated. Further, at the time of reproduction, since the time axis error is corrected before the reproduction signal processing, the characteristics of the reproduction signal processing are improved, and a high-quality reproduced video signal is obtained.
In addition, since the time axis correction means is also used at the time of recording and at the time of reproduction, recording performance and reproduction performance can be improved at low cost.

[Brief description of the drawings]

1 is a block diagram of a recording system according to an embodiment of the present invention, FIG. 2 is a block diagram of a reproducing system, and FIG. 3 is a combination of the recording system of FIG. 1 and the reproducing system of FIG. It is a basic block diagram of a recording / reproducing system. 12: Y / C separation circuit, 14: FM modulation circuit, 26, 34, 46, 78, 8
4 ... Phase comparison circuit, 28,50,56,80 ... VCO, 40,66 ... Time axis correction circuit, 42 ... CCD (variable delay line), 86 ... Crystal oscillator

Claims (1)

(57) [Claims] A correcting means for correcting a time axis of a composite video signal obtained by multiplexing a luminance signal and a chrominance signal; and a format suitable for recording a composite video signal obtained by multiplexing a luminance signal and a chrominance signal. Recording processing means for converting the color video signal from the recording processing means to a recording medium; reproducing means for reproducing the color video signal from the recording medium; and Playback processing means for converting the composite video signal into the original format composite video signal. At the time of recording, the correction means corrects the time axis of the input composite video signal, and converts the composite video signal from the correction means into the recording processing means. And at the time of reproduction, the correction means corrects the time axis of the reproduced color video signal, and A recording / reproducing apparatus for outputting a color video signal from a stage to the reproduction processing means.