JP3114754B2 - Video signal recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for recording and reproducing a wide screen signal having video information compressed in the horizontal direction on the assumption that the image is expanded in the horizontal direction in a wide aspect ratio television. And a video signal recording and reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, in order to reduce noise, video signals are emphasized to raise the level of a high-frequency band and recorded on a recording medium, and at the time of reproduction, the video signals are de-emphasized with a characteristic opposite to emphasis to obtain a high frequency. Lowering the level of the band has been performed.

[0003]

However, emphasis and de-emphasis degrade the waveform of a video signal.

When the emphasis and de-emphasis have non-linear characteristics, waveform distortion is further increased.

Further, when a video section including the compressed video information of the above-described wide screen signal is expanded in a horizontal direction by a television monitor having an idle aspect ratio (hereinafter, referred to as a "wide screen monitor"), emphasis occurs. Alternatively, waveform distortion due to de-emphasis is enlarged.

A first object of the present invention is to provide a video signal recording device in which even if a wide screen signal is recorded on a recording medium, waveform distortion due to emphasis does not expand.

A second object of the present invention is to provide a video signal reproducing apparatus in which waveform distortion due to de-emphasis does not expand even when a wide screen signal is reproduced.

A third object of the present invention is to provide a video signal recording / reproducing apparatus which does not increase waveform distortion due to emphasis and de-emphasis even when recording and reproducing a wide screen signal.

[0009]

According to a first aspect of the present invention, there is provided a video signal recording apparatus having a wide aspect ratio having a horizontally compressed video information in a wide aspect ratio television on the assumption that the video information is expanded in a horizontal direction. A video signal recording apparatus for recording a screen signal on a recording medium via an emphasis circuit, wherein a time constant control means (for example, an embodiment) for changing a time constant of the emphasis circuit according to a compression ratio of a video signal of a wide screen signal. Is provided with a wide-screen signal detector 48).

A video signal recording apparatus according to a second aspect of the present invention provides a de-emphasis circuit for a wide screen signal having video information compressed in the horizontal direction on the assumption that the video signal is expanded in the horizontal direction in a television having a wide aspect ratio. A time constant control means for changing a time constant of a de-emphasis circuit in accordance with a compression ratio of video information of a wide screen signal (for example, the wide screen signal detector 100 of the embodiment). ).

According to a third aspect of the present invention, there is provided a video signal recording apparatus for emphasizing a wide screen signal having video information compressed in the horizontal direction on the assumption that the image is expanded in the horizontal direction in a television having a wide aspect ratio. A video signal recording and reproducing apparatus for recording on a recording medium via a de-emphasis circuit and for reproducing a wide screen signal through a de-emphasis circuit,
When recording a video signal of a wide screen signal, first time constant control means (for example, the wide screen detector 48 of the embodiment) for shortening the time constant of the emphasis circuit and reproduction of the video signal of the wide screen signal are performed. A second time constant control means (for example, the wide screen detector 100 of the embodiment) for shortening the time constant of the de-emphasis circuit when performing the operation is provided.

[0012]

In the video signal recording apparatus of the first aspect, when the wide screen signal is recorded on the recording medium, the time constant control means controls the emphasis circuit according to the compression ratio of the video signal of the wide screen signal. Since the time constant can be shortened, waveform distortion due to emphasis does not increase.

In the video signal reproducing apparatus according to the second aspect, when the wide screen signal is reproduced, the time constant of the de-emphasis circuit is controlled by the time constant control means in accordance with the compression ratio of the video information of the wide screen signal. Can be shortened, so that waveform distortion due to de-emphasis does not increase.

In the video signal recording / reproducing apparatus of the third aspect, when the wide screen signal is recorded on the recording medium, the first time constant control means controls the compression ratio of the wide screen signal according to the compression ratio of the video signal. The time constant of the emphasis circuit can be shortened, and when the wide screen signal is reproduced, the time constant of the de-emphasis circuit is set by the second time constant control means according to the compression ratio of the video information of the wide screen signal. Since the length can be shortened, waveform distortion due to emphasis and de-emphasis does not increase.

[0015]

FIG. 1 shows the configuration of an embodiment of a video signal recording apparatus according to the present invention. This embodiment is an example in which the present invention is applied to an 8 mm video tape recorder (hereinafter, referred to as a VTR). The input video signal is separated into a luminance signal and a color signal by a comb filter 4, the luminance signal is supplied to a low-pass filter 6, and the color signal is supplied to a band-pass filter 22.

The luminance signal passed through the low-pass filter 6 is subjected to non-linear emphasis by a non-linear emphasis circuit 8, pre-emphasis by a pre-emphasis circuit 10, and white and black levels clipped by a white / black clip circuit 12. You.
The nonlinear emphasis circuit 8, the pre-emphasis circuit 10, and the white / black clip circuit 12 constitute an emphasis circuit block E.

The time constant of the emphasis characteristic of the emphasis circuit block E is configured to be changed according to the compression ratio of the video signal of the wide screen signal. That is, when the wide screen signal detector 48 detects that the signal is a wide screen signal by the wide screen signal identification signal or the wide screen track control signal inserted in the vertical synchronization signal, the time constant of the emphasis circuit block E is short. Be killed.

Here, the wide screen signal will be described with reference to FIG. FIG. 3 shows a wide-screen signal having video information compressed in the horizontal direction on the assumption that it is expanded in the horizontal direction in a television having a 16: 9 wide aspect ratio, and a television having a 4: 3 aspect ratio. And a normal video signal reproduced in the step (b) are shown in relation to a wide-screen TV monitor and a normal TV monitor. Three image sources are shown on the left side of FIG. 3, the image source shown above is a black rectangle of 4: 3 horizontal to vertical with a white circle in the center, The image source shown is a 16: 9 black rectangle with a white circle in the center and the white circles of both image sources are identical.
Since the video information of the above image source can be displayed as it is on a normal TV monitor, it is inserted into a video signal of a normal standard without being compressed in the horizontal direction. The video information of the lower image source is a wide screen T having a 16: 9 wide aspect ratio.
Assuming that the V monitor expands in the horizontal direction, it is compressed in the horizontal direction and inserted into a video signal of a normal standard. The compression ratio of the video information of the lower image source to the video information of the upper image source is 3/4. The expansion ratio of the compressed video information of the lower image source on a wide-screen TV monitor having a 16: 9 wide aspect ratio is 4 /
3.

FIG. 4 shows an example of the configuration of the pre-emphasis circuit 10. In this circuit, a resistor Rb and a capacitor C connected in parallel are connected in series to an input terminal, and a resistor Ra is connected in parallel to two output terminals. The time constant of the emphasis characteristic is determined by the value of the resistor Rb and the capacitor C
Is determined by the product τ with the capacitance value of. FIG. 5 shows waveforms after emphasis when the time constant τ is long and short. As shown in this figure, if the time constant τ is long, so-called whiskers extend, so that waveform distortion occurs due to clipping. Such distortion can be reduced by shortening the time constant τ.
Can be reduced or eliminated. In the embodiment of FIG. 1, at least one of the resistor Rb and the capacitor C is made variable, and at least one of the resistor Rb and the capacitor C is shortened in accordance with the wide screen detection signal from the wide screen detector 48 so that the time constant τ becomes short. Change the value of.

The luminance signal output from the emphasis circuit block E is frequency-shifted by the fH / 2 shift circuit 14, frequency-modulated by the FM modulator 16, and input to one input of the mixer 20 via the trap circuit 18. It is supplied to the terminal.

The color signal that has passed through the band-pass filter 22 is subjected to amplitude adjustment by an ACC (automatic chroma control) circuit 24, and then to a chroma emphasis circuit 2.
6, chroma emphasis is applied. The time constant of the emphasis characteristic of the chroma emphasis circuit 26 is
It is configured to be changed according to the compression ratio of the video signal of the wide screen signal. That is, when the wide screen signal detector 48 detects a wide screen signal, the time constant of the chroma emphasis circuit 26 is shortened. When the chroma emphasis circuit 26 is configured by an analog circuit, for example, the time constant can be shortened by changing the value of the series resistance R of the series resonant LCR circuit and changing the Q of the circuit.

FIG. 6 shows an example in which the chroma emphasis circuit 26 is constituted by a digital circuit. The color signal, that is, the color difference signal, is supplied to the minus terminal of the adder 22, supplied to one input of the adder 133 via the coefficient multiplier 131, and added via the coefficient multiplier 132 and the unit delay 134. Is supplied to the other input of the device 133. The coefficient multipliers 131 and 132, the adder 133, and the unit delay unit 134 constitute the high-pass filter 130. The output of the adder 133 is supplied to one input terminal of the adder 144. The output of the adder 144 is supplied to the non-linear conversion circuit (ROM) 141 and also to the other input terminal of the adder 144 via the non-linear conversion circuit (ROM) 142 and the unit delay 145. The output of the nonlinear conversion circuit 141 is supplied to a plus terminal of the adder 122. Nonlinear conversion circuits 141 and 142,
The adder 144 and the unit delay 145 are connected to the limiter 1
40. FIG. 8 shows the input / output characteristics of the nonlinear conversion circuit 142, that is, the characteristics of the gain GBE, and FIG. 9 shows the input / output characteristics of the nonlinear conversion circuit 141, that is, the characteristics of the gain GAE.

The coefficients C and D of the coefficient multipliers 131 and 132 and the gains GAE and GBE of the non-linear conversion circuits 141 and 142 have the chroma emphasis characteristic when the wide screen detection signal is supplied from the wide screen signal detector 48. The time constant is adjusted to be shorter.

FIG. 10 shows a chroma emphasis characteristic for a conventional video signal (FIG. 10A) and a chroma emphasis characteristic for a wide screen signal in which the time constant τ is 1 / 1.333 (FIG. 10A). b)). In the figure,
f0 indicates a subcarrier frequency.

Returning to FIG. 1, the chroma emphasis circuit 2
6 is converted into a low-frequency conversion color signal by the frequency conversion circuit 44,
0 is supplied to the other input terminal of the mixer 20.
An AFC circuit 40 connected to the frequency conversion circuit 28,
The VCO 42 and the frequency conversion circuit 44 are circuits for accurately producing a recording frequency based on the horizontal synchronizing signal fH and a 3.58 MHz reference signal. A phase inversion circuit 46 provided between the frequency conversion circuits 44 and 28 is a circuit for shifting the color phase by 180 ° for each field.

The luminance signal and the low-frequency conversion color signal mixed by the mixer 20 are amplified by a recording amplifier 32 and then recorded on a magnetic tape 36 by a magnetic head 34.

FIG. 2 is a block diagram showing the configuration of an embodiment of a video signal reproducing apparatus according to the present invention. This embodiment is an example in which the present invention is applied to an 8 mm VTR. Magnetic tape 3
The video signal read from 6 by the magnetic head 52 and amplified by the reproduction amplifier is supplied to trap circuits 56 and 76. The trap circuit 56 extracts a luminance signal from the input video signal,
Extracts a low-frequency conversion color signal from an input video signal.

The luminance signal output from the trap circuit 56 is adjusted in level by an AGC / dropout control circuit 58, compensates for dropout, and is made constant in amplitude by a soft limiter 60. The luminance signal output from the limiter 60 is output to the FM demodulator 62
After the frequency demodulation is performed, the signal is supplied to a de-emphasis circuit 66 via a low-pass filter / equalizer 64, where it is subjected to de-emphasis, and further subjected to non-linear de-emphasis by a non-linear de-emphasis circuit 68. De-emphasis circuit 66
Has a characteristic opposite to the characteristic of the pre-emphasis circuit 8 of FIG. 1, and the nonlinear de-emphasis circuit 68 has an opposite characteristic of the nonlinear emphasis circuit 8 of FIG.

The de-emphasis circuit 66 and the nonlinear de-emphasis circuit 68 constitute a de-emphasis circuit block D. The time constant of the de-emphasis characteristic of the de-emphasis circuit block D is configured to be changed according to the compression ratio of the video signal of the wide screen signal. That is, the wide screen signal detector 100
Detects the wide screen signal by the wide screen signal identification signal or the wide screen track control signal inserted in the vertical synchronization signal, the time constant of the emphasis circuit block D is shortened.

The luminance signal output from the nonlinear de-emphasis circuit 68 has its noise removed by a noise canceller 70 and is supplied to one input terminal of a mixer 72 via a comb filter 72.

The color signal extracted by the trap circuit 76 is subjected to amplitude adjustment by the ACC circuit 78 and then converted to a higher frequency by the frequency conversion circuit 80. AFC circuit 9 connected to frequency conversion circuit 80
0, the VCO 92, the APCDEC circuit 94, and the frequency conversion circuit 96 create a conversion carrier based on the horizontal synchronization signal fH and the 3.58 MHz reference signal,
This is a circuit for applying feedback so as to cancel jitter included in the reproduced color signal. A phase inversion circuit 98 provided between the frequency conversion circuits 96 and 88 is a circuit for shifting the color phase by 180 ° for each field.

The color signal output from the frequency conversion circuit 80 is supplied to a chroma de-emphasis circuit 86 via a band-pass filter 82 and a comb filter 84, where the chroma signal is subjected to chroma de-emphasis.
The chroma de-emphasis 86 has characteristics opposite to those of the chroma emphasis circuit 26 of FIG. The time constant of the de-emphasis characteristic of the chroma de-emphasis circuit 86 is configured to be changed according to the compression ratio of the video signal of the wide screen signal. That is, when the wide screen signal detector 100 detects that the signal is a wide screen signal, the time constant of the chroma de-emphasis circuit 86 is shortened.

FIG. 7 shows a chroma de-emphasis circuit 26.
Is an example in which is constituted by a digital circuit. The color signal, that is, the color difference signal is supplied to the plus terminal of the adder 222. The output of the adder 222 is supplied to one input of an adder 233 via a coefficient multiplier 231, and is also supplied to the adder 2 via a coefficient multiplier 232 and a unit delay unit 234.
33 is supplied to the other input. The coefficient multipliers 231 and 232, the adder 233, and the unit delay unit 234
The high-pass filter 230 is configured. The output of the adder 233 is supplied to one input terminal of the adder 244. The output of the adder 244 is a non-linear conversion circuit (ROM) 241
And a non-linear conversion circuit (ROM) 24
2 and the other input terminal of the adder 244 via the unit delay 245. The output of the nonlinear conversion circuit 241 is supplied to a minus terminal of the adder 222. The non-linear conversion circuits 241 and 242, the adder 244, and the unit delay 245 constitute the limiter 240.

The coefficients C and D of the coefficient multipliers 231 and 232, and the gains GAD and GBD of the non-linear conversion circuits 241 and 242, when the wide screen signal is supplied from the wide screen signal detector 100, the chroma de-emphasis characteristic. Is adjusted so that the time constant of

The color signal output from the chroma de-emphasis circuit 86 is supplied to the other input terminal of the mixer 74, where it is mixed with the luminance signal and supplied as a video signal output to, for example, a wide screen monitor. You.

FIG. 11 (a) shows that the color bar of the wide screen signal is changed to 8 mm VT without changing the time constants of the emphasis and de-emphasis characteristics as in the prior art.
The output of the chroma emphasis circuit, the output of the chroma de-emphasis circuit, and the video signal of the wide aspect ratio television when recorded and reproduced on R are shown in FIG. The output of the chroma emphasis circuit, the output of the chroma de-emphasis circuit, and the video signal of the wide aspect ratio television when the color bar of the wide screen signal is recorded and reproduced on an 8 mm VTR with the constants shortened are shown. As is clear from FIG. 11, if the time constant is not changed as in the prior art, the rise of the video portion of the video signal is slowed down, and the waveform is greatly deteriorated. Of the image portion becomes sharp, and the waveform deterioration is small.

Although the above embodiment relates to an 8 mm VTR, the present invention is not limited to the case where a video signal is recorded and reproduced on a magnetic tape in a VTR or the like, and generally the video signal is recorded on a recording medium. Applicable when playing.

[0038]

According to the video signal recording apparatus of the first aspect,
When the wide screen signal is recorded on the recording medium, the time constant of the emphasis circuit can be shortened by the time constant control means according to the compression ratio of the video signal of the wide screen signal. The distortion does not increase.

According to the second aspect of the present invention, when the wide screen signal is reproduced, the time constant of the de-emphasis circuit is set by the time constant control means in accordance with the compression ratio of the video information of the wide screen signal. Since the length can be shortened, waveform distortion due to de-emphasis does not increase.

According to the video signal recording / reproducing apparatus of the third aspect, when the wide screen signal is recorded on the recording medium, the first time constant control means controls the emphasis according to the compression ratio of the wide screen signal video signal. The time constant of the circuit can be shortened, and when the wide screen signal is reproduced, the second time constant control means controls the de-emphasis circuit according to the compression ratio of the video information of the wide screen signal. Since the constant can be shortened, waveform distortion due to emphasis and de-emphasis does not increase.

Further, by shortening the time constant of the emphasis and de-emphasis characteristics, a higher frequency (for example, (subcarrier frequency + 500 kHz)
z) The emphasis and de-emphasis curves of frequencies above the frequency can be defined and managed, so that fine signal components which are not conventionally managed and are easily visible on a wide-screen TV monitor can be managed, and the Image quality deterioration can be prevented. Further, compatibility of the emphasis format is easily obtained, and waveform distortion due to a deviation from the center of the format becomes less noticeable.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a video signal recording device of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of a video signal reproducing device according to the present invention.

FIG. 3 shows a wide screen signal having video information compressed in the horizontal direction on the assumption that it is expanded in a horizontal direction in a television having an aspect ratio of 16: 9, and a television having a 4: 3 aspect ratio. A normal video signal to be reproduced is compared with a wide screen TV monitor and a normal TV signal.
It is explanatory drawing shown in connection with a monitor.

FIG. 4 is a circuit diagram showing one configuration example of a luminance signal pre-emphasis circuit 10 of FIG. 1;

FIG. 5 is a waveform diagram showing a waveform example of a luminance signal after emphasis has been applied by the pre-emphasis circuit of FIG. 4;

FIG. 6 is a block diagram illustrating an example in which the chroma emphasis circuit is implemented by a digital circuit.

FIG. 7 is a block diagram illustrating an example in which the chroma de-emphasis circuit is implemented by a digital circuit.

8 is a graph showing an example of characteristics of the nonlinear conversion circuit 142 in FIG.

FIG. 9 is a graph showing an example of characteristics of the nonlinear conversion circuit 141 of FIG. 6;

FIG. 10 shows a conventional chroma emphasis characteristic example (a);
FIG. 8 is a characteristic diagram showing an example (b) of a chroma emphasis characteristic for a wide screen signal whose time constant is shortened by the present invention.

FIG. 11 shows a video signal signal output of a conventional chroma emphasis circuit, a video signal output of a chroma de-emphasis circuit, a video signal output of a wide screen monitor, and a video signal signal output of a chroma emphasis circuit having a reduced time constant according to the present invention. FIG. 7 is a waveform diagram showing a comparison between a video signal output of a chroma de-emphasis circuit and a video signal output of a wide screen monitor.

[Explanation of symbols]

 8 Non-linear emphasis circuit 10 Pre-emphasis circuit 26 Chroma emphasis circuit 46 Wide screen signal detector 66 De-emphasis circuit 68 Non-linear de-emphasis circuit 86 Chroma de-emphasis circuit 100 Wide screen signal detector

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/91-5/956 H04N 9/79-9/898 G11B 20/02

Claims (3)

(57) [Claims] 1. A video signal recording device for recording a wide screen signal having video information compressed in a horizontal direction on a recording medium via an emphasis circuit on the assumption that the image is expanded in a horizontal direction in a television having a wide aspect ratio. A video signal recording device, comprising: a time constant control unit that changes a time constant of the emphasis circuit according to a compression ratio of video information of the wide screen signal. 2. A video signal reproducing apparatus for reproducing, via a de-emphasis circuit, a wide screen signal having video information compressed in the horizontal direction on the assumption that the image is expanded in the horizontal direction in a television having a wide aspect ratio. And a time constant control means for changing a time constant of the de-emphasis circuit in accordance with a compression ratio of video information of the wide screen signal. 3. A wide screen signal having video information compressed in the horizontal direction on the assumption that the image is expanded in the horizontal direction in a television having a wide aspect ratio is recorded on a recording medium via an emphasis circuit, and In a video signal recording / reproducing apparatus that reproduces a screen signal via a de-emphasis circuit, when recording a video signal of the wide screen signal, first time constant control means for shortening a time constant of the emphasis circuit; A video signal recording / reproducing apparatus, comprising: second time constant control means for shortening a time constant of the de-emphasis circuit when reproducing a video signal of a wide screen signal.