JPH0822086B2 - Video recorder - Google Patents

Description

The present invention relates to a video recording apparatus having a time axis error correction function, and more specifically, even if a luminance signal component has a time axis error, The present invention relates to a video recording device in which the time axis error is not reflected in a recording signal.

[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, when considering the image display, it is not necessary to forcibly correct the time axis error for the luminance signal, but for the color signal, the time axis error causes color unevenness and the like, so it is essential to correct the time axis error. Specifically, the time axis error is corrected at the same time as the frequency conversion for restoring the color signal that has been low-pass converted for recording.

A video signal reproduced and output from such a reproducing apparatus is
Although the chrominance signal component does not include a time axis error, the luminance signal component does include a time axis error. Therefore, for example, when performing dubbing, the luminance signal originally including the time axis error is recorded on the 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, which causes a remarkable deterioration in image quality. Further, when the time base error of the luminance signal is accumulated in this way, finally, the time base error correction of the color signal at the time of frequency conversion becomes impossible.

Therefore, an object of the present invention is to provide a video recording device that overcomes this problem.

[Means for solving problems]

The video recording apparatus according to the present invention includes a first time axis correction means for correcting the time axis of the composite signal so as to cancel the time axis error of the brightness signal in the composite state of the brightness signal and the color signal, and the first time axis correction means. Second time axis correction means for correcting the color signal after separating the output of the time axis correction means into the luminance signal and the color signal based on the reference signal after the time axis correction. To do.

[Operation] The first time-axis correction means corrects the time-axis error of the luminance signal and gives the time-axis error of the same magnitude and in the opposite direction to the color signal. Then, the second time-axis error correction means corrects the time-axis error added to the color signal by the first time-axis correction means. As a result, the signal recorded on the recording medium contains substantially no time base error. Therefore, even if the signal recorded on this recording medium is reproduced, only the time axis error at the time of reproduction is added,
Accumulation of time axis error does not occur.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. still,
Y is a luminance signal, C is a chrominance signal, f _SC is a carrier chrominance signal or its frequency, f _LSC is a low frequency carrier chrominance signal or its frequency, and f _H is a horizontal synchronizing signal or its frequency. Those marked with "*" indicate that a time axis error is included.

In FIG. 1, an input terminal 10 is provided with a video signal output from a conventional reproducing apparatus, that is, a luminance signal including a time axis error.
It is assumed that a composite video signal including Y ^* and a carrier color signal f _SC that does not include a time axis error is input. Reference numeral 40 is a time axis correction circuit, the details of which will be described later, but CC as a variable delay element.
Correct the Y ^* time base error by D42. As a result, the same time axis error is added to the carrier color signal C in the opposite direction.

The output of the time axis correction circuit 40 is separated into a luminance signal Y and a carrier color signal C ^* (or _fSC ^* ) by the Y / C separation circuit 12, and the Y signal is FM.
It is FM-modulated by the modulation circuit 14 and applied to the adder 16. The carrier color signal f _SC ^* is applied to the multiplier 18, and the carrier (f _SC ^* + f _LSC ) that reflects the time axis error of the input Y ^* signal is applied to the multiplier 18, as described below. Therefore, the multiplier 18
Outputs a low-frequency carrier color signal f _LSC that does not include a 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, and the phase comparison circuit 26 includes a horizontal synchronization signal f that does not include a time axis error extracted from the luminance signal separated by the Y / C separation circuit 12. _H is applied. The phase comparison circuit 26 compares the phase of the horizontal synchronizing signal f _H with the output of the frequency divider 30, and outputs the phase difference signal as VC.
Apply to O28. VCO28 has a frequency depending on the phase difference signal.
It oscillates at 378f _H , and the frequency divider 30 divides the output of the VCO 28 into 1/378 and feeds it back to the phase comparison circuit 26. After all, VCO2
The output of 8 does not include a time base error, and is divided by 1/8 by the frequency divider 32 to form a carrier of frequency f _LSC .

The phase comparison circuit 34 and the VXO 36 also form a PLL circuit, and the phase comparison circuit 34 supplies the carrier color signals f _SC ^* and VXO from the Y / C separation circuit 12.
Phase compare with 36 outputs. The VXO 36 outputs a signal (referred to as f _SC ^* for convenience of explanation) in synchronization with the carrier color signal f _SC ^* .
The multiplier 38 multiplies the carrier f _SC ^* from the VXO 36 and the carrier f _LSC from the frequency divider 32 to output a carrier (f _SC ^* + f _LSC ), which is applied to the multiplier 18. As a result, as described above,
The multiplier 18 outputs the low-frequency carrier color signal f _LSC that does not include the time axis error.

Next, the operation of the time axis correction circuit 40 will be described. PLL circuit 41
Is a circuit similar to the PLL circuit including the phase comparison circuit 26, the VCO 28, and the frequency divider 30, and extracts the horizontal synchronization signal f _H ^* from the luminance signal including the time axis error of the input terminal 10 and has a frequency of 378.
The carrier including the time base error is output at f _H. Divider 44
The output of the PLL 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
Under the control of the clock, 2 acts to cancel the Y ^* time axis error with respect to the input multiplex signal (Y ^* + _fSC ). That is, the time axis correction circuit 40 corrects the time axis error in the luminance signal, while the carrier color signal includes the time axis error in the opposite direction.

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

〔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.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 12 ... Y / C separation circuit, 14 ... FM modulation circuit, 26,34,46 ... Phase comparison circuit, 28,50,56 ... VCO, 40 ... Time axis correction circuit, 42 ... CCD
(Variable delay line)

Claims (1)

[Claims] 1. A device for recording a video signal on a recording medium, wherein the time axis of the composite signal is corrected so as to cancel the time axis error of the brightness signal in the composite state of the brightness signal and the color signal. Second time axis correction means for correcting the time axis correction means and the color signal after separating the output of the first time axis correction means into the luminance signal and the color signal based on the reference signal after the time axis correction. A video recording apparatus comprising: