JPH0411435Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a video tape recorder capable of recording and reproducing using one delay circuit.

Conventionally, video tape recorders separate the recorded video signal input into a luminance signal and color signal during recording and process them, and during playback, separate the playback signal from the head with a filter and demodulate the resulting luminance signal and color signal, which are then synthesized. In order to form a reproduced video signal, a signal processing circuit shown in FIG. 1 is provided.

During recording, the aforementioned recording video signal is input to the first input terminal (INa), and this video signal is sent to the first mixer (MIXa) and the second mixer (MIXb).
is directly supplied to
The signal is supplied to both mixers (MIXa) and (MIXb) via a first delay line (DLa) for delay (referred to as 1H).

At this time, the recorded video signal at the first input terminal (INa) and the stored video signal delayed by 1H have a relationship in which the luminance signal components are in phase and correlated, and the color signal components are in opposite phase.

Then, a luminance signal is separated and formed by additive mixing in the first mixer (MIXa), and this signal is output from the first output terminal (OUTa).

In addition, the color signal is separated and formed by subtractive mixing in the second mixer (MIXb), and this signal is 3.58MHz
The signal is output from the second output terminal (OUTb) via the bandpass filter circuit (BPF).

Next, during reproduction, the luminance signal (FM signal) included in the reproduction signal of the magnetic tape (not shown) is supplied to the second input terminal (INb), and the magnetic tape is supplied to the first input terminal (INa). A color signal included in the tape playback signal is supplied.

Then, the luminance signal of the second input terminal (INb) is
Trop-out compensation switch circuit (SWa) that compensates for Trop-outs caused by scratches on magnetic tape, etc.
The luminance signal demodulated by this demodulator (DECa) is supplied to the third and fourth mixers MIXc (MIXd).

In addition, the second delay line (DLb) for 1H delay
It is delayed by 1H and supplied to the second demodulator (DECb),
The demodulated luminance signal delayed by 1H from the demodulator (DECb) is supplied to the fourth mixer (MIXd).

Then, the fourth mixer (MIXd) subtracts and synthesizes the luminance signals of the demodulators (DECa) and (DECb),
Through this synthesis, the noise component of the luminance signal is extracted as a noise signal for filter processing.

This noise signal is also input to the third mixer (MIXc) via the limiter (LMt), and this mixer (MIXc) subtracts and synthesizes the output signal of the demodulator (DECa) and the noise signal of the limiter (LMt). Noise removal filter processing is performed, and the luminance signal of the third mixer (MIXc) from which noise has been removed through this processing is supplied to the fifth mixer (MIXe) via the de-emphasis circuit (DES).

On the other hand, the color signal of the first input terminal (INa) is
1st, 2nd mixer (MIXa), (MIXb) and 1st
Supplied to the delay line (DLa).

Then, the color signal of the first input terminal (INa) and the color signal delayed by 1H of the first delay line (DLa) are subtracted and combined in the second mixer (MIXb), and this combination eliminates the crosstalk component of the color signal. removed.

Furthermore, the color signal from the second mixer (MIXb) from which crosstalk components have been removed is supplied to the fifth mixer (MIXe), where the demodulated luminance signal and color signal are combined and reproduced. A video signal is formed and this signal is output from the third output terminal (OUTc) via the skew correction switch circuit (SWb).

By the way, during special playback, etc., the reproduced video signal of the fifth mixer (MIXe) is supplied to the third delay line (DLc) for skew correction via the modulator (MDL), and this delay line (DLc) The playback video signal is modulated and delayed by 0.5H, and
The skew correction switch circuit (SWb) performs switching operation.

Then, the 0.5H delayed signal of the third delay line (DLc) is returned to a video signal by the third demodulator (DECc), and the skew correction switch circuit (SWb)
is output from the third output terminal (OUTc) via
Skew correction is performed using the playback video signal delayed by 0.5H.

Furthermore, during the aforementioned dropout compensation, the dropout compensation switch circuit (SWa) performs a switching operation, and instead of the playback video signal in which the dropout has occurred, the playback video signal from the second delay line (DLb) is sent to the switch circuit (SWa). The signal is output to the first demodulator (DECa) via the signal line, and dropout compensation is performed thereon.

Therefore, Japanese Patent Application Laid-Open No. 55-82583 (HO4N
9/491), one 1H by switching the switch.
A video signal recording and reproducing apparatus is described in which a delay circuit is used for signal separation during recording, crosstalk component removal during reproduction, and dropout compensation.

In addition, Japanese Patent Application Laid-open No. 1983-143021 (HO4N 9/
No. 02) describes a video signal processing circuit in which one 1H delay circuit is used in common for crosstalk component removal, noise component removal, or dropout compensation of a luminance signal during reproduction.

[The problem that the idea aims to solve]

In the case of the conventional video tape recorder shown in FIG. 1, a 1H delay line (DLa) is provided to separate signals during recording and remove sloshtalk components of color signals during playback, and to compensate for dropout of luminance signals during playback. A 1H delay line (DLb) is provided for noise component extraction, and a 0.5H delay line (DLc) is provided for skew correction during special playback.

Further, since three delay lines are provided, there is a problem that the circuit configuration becomes complicated.

Note that each delay line (DLa) to (DLc) has a bandwidth of 2.
It is narrow at ~5 MHz, making it difficult to share it for processing luminance signals and color signals with different bands.

Furthermore, even if one 1H delay circuit described in both of the above publications is used as the delay lines (DLa) and (DLb), in order to perform skew correction during special playback, etc.
A 0.5H delay circuit such as a delay line (DLc) must be prepared separately, which does not simplify the circuit configuration.

The object of the present invention is to provide a video tape recorder that can perform signal separation during recording, crosstalk component removal and dropout compensation during playback, and skew correction during special playback by sharing one delay circuit. .

[Means to solve the problem]

In order to achieve the above object, the video tape recorder of the present invention separates and processes the recorded video signal input during recording to output a luminance signal and a color signal, and demodulates and outputs the input luminance signal during playback. , reproduced video signal by combining color signals,
A first predetermined circuit for separating and synthesizing the recorded video signal and the reproduced video signal, which is also used for signal delay during recording and reproduction, is provided in the separation and synthesis circuit unit that outputs a noise signal for filter processing of the signal. a wideband delay circuit that outputs a delayed video signal delayed by a horizontal period, and outputs from a skew output terminal a skew-corrected video signal in which the reproduced video signal is delayed by a second predetermined horizontal period corresponding to a skew amount during special playback, etc.; During recording, the delayed video signal is added and mixed to the recorded video signal to separate and extract the luminance signal, and during reproduction, the delayed video signal is added and mixed to the difference signal between the luminance signal and the color signal to generate the luminance signal of the reproduced video signal. a mixer for signal separation and noise removal that removes noise components and crosstalk components of color signals; and the noise signal during reproduction is fed back and supplied via a first correction switch circuit, and the input signal of the broadband delay circuit is supplied with the noise signal. a dropout compensation switch circuit comprising a mixer for skew correction that subtracts and mixes a noise signal, and returns the delayed video signal to the input side of the separation/synthesis circuit section during playback to compensate for dropout of the playback video signal; and a second correction switch circuit that outputs the skew-corrected video signal instead of the reproduced video signal during correction.

[Effect]

In the video tape recorder of the present invention configured as described above, the delayed video signal formed by the first horizontal period delay of the wideband delay circuit is supplied to the mixer for signal separation and noise removal, and the delayed video signal is Noise components and crosstalk components of the synthesized reproduced video signal are removed during signal separation and reproduction.

Furthermore, when a dropout occurs during playback, the delayed video signal is fed back to the separation/synthesis circuit section via the dropout correction switch circuit, and the input signal of this circuit section is replaced with the delayed video signal to perform dropout compensation. .

Furthermore, during special playback, etc., the noise signal for the filter formed by the synthesis process is fed back to the input side of the delay circuit via the first correction switch circuit to the mixer for skew correction, The output signal is delayed by a second horizontal period in the delay circuit and skew corrected, and a skew corrected video signal is output from the skew output terminal.

Then, when a skew occurs, the second correction switch circuit outputs a skew correction video signal instead of the reproduced video signal, and skew correction is performed.

Therefore, one wideband delay circuit can perform signal separation during recording, removal of crosstalk components during playback, dropout compensation, and skew correction during special playback.

〔Example〕

One embodiment will be described with reference to FIG.

As shown in FIG. 2, during recording, a demodulated recording video signal is supplied to the input terminal (INA), and this signal is passed through the dropout compensation switch circuit (SWA) to the first and second input terminals of the separation/synthesis circuit section 1. 2
Supplied to mixers (MIXA) and (MIXB).

The recorded video signal of the first mixer (MIXA) is transferred directly to the third and fourth mixers (MIXC).
(MIXD).

In addition, the recorded video signal of the second mixer (MIXB) is passed through a fifth mixer (MIXE) for skew correction as a skew mixer to a 0 to 4 MHz signal of a charge transfer element (CCD element) configuration. The signal is supplied to a wideband delay circuit (DLY) with a sufficiently wide band.

This delay circuit (DLY) delays the recording video signal, that is, the input video signal, by 1H as the first predetermined horizontal period for separation and synthesis, and
The delayed video signal delayed by 1H is supplied to the third and fourth mixers (MIXC) and (MIXD).

Then, the third mixer (MIXC) for signal separation noise removal adds and mixes the recorded video signal of the first mixer (MIXA) and the delayed video signal of the delay circuit (DLY), and at this time, the luminance of the video signal Since the components have a horizontal correlation of 1H, the luminance signal of the recorded video signal is separated and output.

In addition, the fourth mixer (MIXD) adds and mixes the recorded video signal of the first mixer (MIXA) and the delayed video signal of the delay circuit (DLY), and at this time, the color components of the video signal alternate every 1H. The color signals of the recorded video signal are separated and output because they are in an opposite phase relationship.

This color signal includes uncorrelated components and true noise components of the recorded video signal.

Then, the output signal of the fourth mixer (MIXD) is supplied to the low-pass filter (LPF) of the first filter section 2 and the second filter section 3 having a 3.58MHz band-pass filter configuration, and the low-pass filter (LPF)
The uncorrelated component and the noise component are separated and extracted, and the second filter section 3 extracts the color signal.

Furthermore, the output signal of the low-pass filter (LPF) and the luminance signal of the third mixer (MIXC) are supplied to the sixth mixer (MIXF) of the first filter section 2, where they are added and mixed, and the luminance signal is adjusted by uncorrelation compensation. Uncorrelated components are compensated.

Further, the noise component of the output signal of the low-pass filter (LPF) is extracted as a noise signal by the limiter circuit (LMt) of the limiter section 4, and this noise signal is supplied to the seventh mixer (MIXG) of the limiter section 4. The mixer (MIXG) subtracts and mixes the output signal of the sixth mixer (MIXF) and the noise signal to remove the noise component of the luminance signal.

Then, the luminance signal of the seventh mixer (MIXG) is outputted from the output terminal (OUTA) via the second correction switch circuit (SWC), and the color signal of the second filter section 3 is outputted from the output terminal (OUTB). Ru.

Next, during playback, the playback signal from the magnetic tape is filtered and demodulated into a luminance signal (FM signal) and a color signal, and the demodulated luminance signal is supplied to the input terminal (INA) and the input terminal (INB).
A color signal is supplied to the

Then, the luminance signal at the input terminal (INA) is supplied to the first and second mixers (MIXA) and (MIXB) via the switch circuit (SWA), and the color signal at the input terminal (INB) is directly supplied to both mixers. Supplied to (MIXA) and (MIXB).

Furthermore, a difference signal between the luminance signal and the color signal is formed by subtractive mixing in the first mixer (MIXA),
A sum signal of a luminance signal and a color signal corresponding to a reproduced video signal is formed by additive mixing in the second mixer (MIXB).

Then, the difference signal is sent to the third and fourth mixers (MIXC),
(MIXD) to the third and fourth mixers (MIXA),
(MIXB) is supplied as is.

In addition, the sum signal is supplied to the delay circuit (DLY) via the fifth mixer (MIXE), and the delayed video signal obtained by delaying the reproduced video signal by 1H is sent from the delay circuit (DLY) to the third and fifth mixer (MIXC ),
(MIXD).

Then, 2 of the third mixer (MIXC) shifted by 1H.
By adding and mixing the signals, the luminance signal and the color signal are combined with the signal level doubled, and a reproduced video signal with the signal level doubled is formed.

At this time, since the signal level is doubled, uncorrelated noise components and crosstalk are removed from the luminance signal with horizontal correlation and the color signal with interleaving, that is, anti-phase relationship, and the noise component of the luminance signal and the color signal are removed. Crosstalk components of the signal are removed.

Further, by subtractive mixing in the fourth mixer (MIXD), uncorrelated components and uncorrelated noise components of the luminance signal are extracted as noise signals for filter processing.

This noise signal is passed through a low pass filter (LPF)
is supplied to a sixth mixer (MIXF) through which the output signal of the third mixer (MIXC) and the noise signal are additively mixed to perform decorrelation compensation of the reproduced video signal. .

In addition, the uncorrelated noise component included in the output signal of the low-pass filter (LPF), that is, the true noise component caused by the magnetic tape, etc., is extracted by the limit circuit (LMt) and sent to the seventh mixer (MIXG).
The true noise component of the luminance signal in the reproduced video signal is removed by subtractive mixing in this mixer (MIXG).

Note that the level of the true noise component is lower than that of the luminance signal having no horizontal correlation.

Then, the reproduced video signal of the seventh mixer (MIXG) is outputted from the output terminal (OUTA) via the second correction switch circuit (SWC).

By the way, dropouts in the reproduced luminance signal due to scratches on the magnetic tape or the like are detected from the signal before demodulation, and when this detection occurs, the switch circuit (SWA) performs a switching operation.

By this switching operation, the delayed video signal of the delay circuit (DLY) is fed back to the first mixer (MIXA) via the switch circuit (SWA), and dropout compensation is performed using the signal from 1H earlier.

In addition, during special playback in which the tape is played back by running at a speed different from that during recording, the first and second correction switch circuits for skew correction are used to compensate for the time lag between recording and playback, that is, to perform skew correction. (SWB) and (SWC) perform switching operations.

Then, by the switching operation of the switch circuit (SWB), the noise signal of the fourth mixer (MIXD) is fed back to the fifth mixer (MIXE) for skew correction, and this mixer (MIXE) feeds back the noise signal to the second mixer (MIXB). ) and the nozzle signal are subtracted and mixed.

Further, the output signal of the fifth mixer (MIXE) is supplied to the delay circuit (DLY), and at this time, the delay circuit (DLY) connects the switch circuit (SWC) from the skew output terminal (do) provided as a tap output terminal. Then, a skew-corrected video signal is outputted by delaying the input video signal by a second predetermined horizontal period corresponding to the skew amount, that is, 0.5H.

Then, by the switching operation of the switch circuit (SWC), during skew correction, the skew correction video signal is output from the output terminal (OUTA) instead of the playback video signal, and the skew correction of the playback video signal is performed.

[Effect of idea]

Since the present invention is configured as described above, it produces the effects described below.

One broadband delay circuit (DLY) is provided in the separation and synthesis circuit section 1, and the delayed video signal formed by the first horizontal period delay of the delay circuit (DLY) is mixed for signal separation and noise removal during recording and playback. By adding and mixing the mixer (MIXC), the luminance signal is separated and extracted during recording.
During reproduction, the noise component of the luminance signal and the crosstalk component of the color signal are removed.

Further, when a dropout occurs during playback, the delayed video signal is fed back to the input side of the separation/synthesis circuit section 1 by a dropout compensation switch circuit (SWA) to perform dropout compensation.

Furthermore, during special playback, etc., the noise signal for the filter formed by the synthesis process is sent to the skew correction mixer (MIXE) on the input side of the delay circuit (DLY) to the first correction switch circuit (SWB).
The output signal of the mixer (MIXE) for skew correction is fed back through the delay circuit (DLY).
A skew-corrected video signal is formed by being delayed by a horizontal period of , and this signal is output from a second compensation switch circuit (SWC) in place of the reproduced video signal.

Therefore, signal separation during recording, crosstalk component removal during playback, dropout compensation, and skew correction during special playback can be performed by providing one delay circuit, and the circuit configuration is greatly simplified.

[Brief explanation of the drawing]

FIG. 1 is a block wiring diagram of a conventional example, and FIG. 2 is a block wiring diagram of an embodiment of the video tape recorder of this invention. 1...Separation and synthesis circuit section, (DLY)...Wideband delay circuit, (MIXC)...Third mixer for signal separation and noise removal, (MIXE)...Fifth mixer for skew correction, (SWA) ...dropout compensation switch circuit, (SWB), (SWC) ...first and second correction switch circuits, (do) ...skew output terminal.

Claims (1)

[Claims for Utility Model Registration] Separately processing input recording video signals during recording to output luminance signals and color signals, and demodulating and processing the input luminance signals and color signals during playback to synthesize and reproduce video. A first separation/synthesis circuit section that outputs a signal and a noise signal for filter processing of the signal is provided with a first separation/synthesis circuit section which is also used for signal delay during recording and reproduction, and is used for separating and synthesizing each of the recorded video signal and the reproduced video signal. a wideband delay circuit that outputs a delayed video signal delayed by a predetermined horizontal period, and outputs from a skew output terminal a skew-corrected video signal delayed by a second predetermined horizontal period corresponding to the amount of skew of the reproduced video signal during special playback, etc.; , during recording, the delayed video signal is added and mixed to the recorded video signal to separate and extract a luminance signal, and during reproduction, the delayed video signal is added and mixed to the difference signal between the luminance signal and the color signal to obtain the luminance signal of the reproduced video signal. a mixer for signal separation and noise removal that removes noise components of the color signal and crosstalk components of the color signal; and the noise signal during reproduction is fed back and supplied via a first correction switch circuit to the input signal of the wideband delay circuit. a dropout compensation switch circuit comprising a mixer for skew correction that subtracts and mixes the noise signal, and returns the delayed video signal to the input side of the separation/synthesis circuit section during playback to perform dropout compensation of the playback video signal; and a second correction switch circuit that outputs the skew-corrected video signal instead of the reproduced video signal during skew correction.