JPH11178009A - Video signal recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate ghosts even from video that is already recorded with ghost in it at the time of reproduction by providing a circuit, which sends a luminance signal output of a recording and reproducing system circuit to a GC circuit and an output system circuit, which performs time matching between a luminance signal output from the GC circuit and a color signal output from the recording and reproducing system circuit and outputs them. SOLUTION: Only a luminance signal, among reproduction signals that are outputted from a recording and reproducing circuit 7, is inputted to a GC circuit 4, and ghost canceling is performed to a recorded matter that does not undergo ghost canceling at the time of being recorded. A Y-signal sent from the circuit 4 is outputted to an video output after its noise is reduced by a noise reduction circuit 9. Also, a C signal sent from the circuit 7 is outputted to the video output after time matching is performed between it and the Y-signal by a delay circuit 10. On the other hand, the Y-signal from the circuit 9 and the C-signal from the circuit 10 are mixed by a YC-mixing circuit 11 and are outputted as a composite signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing ghosts and improving frequency characteristics of a television broadcast signal and a video signal recording / reproducing apparatus to which the method is applied.

[0002]

2. Description of the Related Art A conventional example of a method and a circuit for ghost cancellation and frequency characteristic improvement when these methods and circuits are applied to a magnetic recording / reproducing apparatus will be described.

FIG. 12 shows a ghost cancel circuit (GC).
1 shows a system configuration of an image signal recording / reproducing apparatus provided with a circuit). In the recording operation of this system, the switches 4 and 26 are connected to the R side, and the switch 3 is connected to the A side when receiving a television broadcast and to the B side when receiving an external input from a video camera or the like. Is done.

The input signal is converted into a digital signal by an A / D converter, and then sent to a transversal filter 6 where ghost cancellation is performed. , Where it is converted back to an analog signal and output to an output terminal.

The output of the D / A converter 7 is further sent to a YC separation circuit 13, where it is separated into a Y (luminance) signal and a C (color) signal, which are processed by a Y processing circuit and a C processing circuit, respectively. Thereafter, the signals are added by an addition circuit 16, amplified by a recording amplifier, sent to the head 18, and recorded on the recording medium 20.

In this recording operation, the GCR timing signal generation circuit 11 extracts a GCR timing signal from the output of the A / D converter 5 and supplies it to the GCR extraction circuit and the switch 12. This timing signal indicates a period during which a GCR (ghost cancel reference) signal exists in the insertion line of each field. (The GCR signal is inserted at a predetermined position in the vertical blanking period in the video signal of each field with a period of eight fields).

During this period, the GCR extraction circuit 10 extracts the GCR signal from the output of the transversal filter 6 and sends it to the tap coefficient control circuit 8, where the tap coefficient control circuit
The ghost component is detected by comparing the pulse signal with the pulse signal supplied from the reference waveform generation circuit 9, and the tap coefficient of the transversal filter is calculated.

Since the tap coefficient is calculated so that the pulse signal after passing through the transversal filter becomes equal to the ideal reference pulse signal, when the video signal passes through the transversal filter, ghost or transmission system distortion may occur. A high-quality video signal from which is removed is obtained.

Next, a case where an input signal is input from the external input signal terminal 1 will be described. At this time, switch 3
Is connected to the B side. The input video signal is sent to an A / D converter 5 via a switch 3 and a switch 4, where it is converted into a digital signal and sent to a transversal filter. The signal is sent to the D / A converter 7 through the interface, is converted back to an analog signal, and is output to an output terminal.

The output of the D / A converter 7 is supplied to the YC separation circuit 1
3, Y processing circuit 14, C processing circuit 15, addition circuit 16,
The recording medium 2 is sent to the head 18 via the recording amplifier 17 and
0 is recorded.

When recording the external input, a signal supplied from a GCR (ghost cancel reference) signal generating circuit 28 is added to the output of the transversal filter 6 via the switch 12. In addition, a TV broadcast received by an antenna can be replaced with a new GCR signal.

To reproduce the image signal recorded on the recording medium, the signal is read out by the head 19 and amplified by the preamplifier 21. The Y signal is processed by the Y processing circuit and then sent to the P side of the switch 4. At this time, since the device is in the reproduction mode, the switch 4 is connected to the P side, so that the Y signal is sent to the A / D converter 5 and converted into a digital signal.

After that, the Y signal is corrected for waveform deterioration and frequency characteristics by the transversal filter 6, and
2 to the D / A converter 7. On the other hand, the C signal is signal-processed by a C processing circuit 23, delayed by a delay circuit 24 for time adjustment, and sent to an addition circuit 25. The Y signal from the D / A converter 7 and the C signal from the delay circuit 24 are added by the adding circuit 25 and output to the output terminal through the P side of the switch 26.

[0014]

In the above-described conventional magnetic recording / reproducing apparatus, recording is performed by performing ghost cancellation during recording, but ghost cannot be removed during reproduction. Therefore, when an image having a ghost was recorded, the ghost could not be removed later.

Further, for an image recorded without adding a GCR signal at the time of recording, there was no reference signal for adjusting the frequency characteristics of the reproduced image, so that the frequency characteristics could not be optimized.

[0016]

In order to solve the above problems, the present invention provides a video signal recording / reproducing apparatus having the following means. That is, a video signal input system circuit including a TV broadcast receiving system circuit, an external input terminal, and an input switching circuit for switching between them, and a GCR signal included in a video signal sent from the video signal input system circuit are detected. And performs ghost cancellation and / or correction of frequency characteristics, and outputs a result thereof. A GC circuit that divides the output of the GC circuit into a luminance signal and a chrominance signal; A circuit for transmitting the luminance signal output of the recording and reproduction system circuit to the GC circuit;
An image signal recording / reproducing apparatus comprising: an output system circuit for synchronizing a luminance signal output from a C circuit and a color signal output from a recording / reproducing system circuit to a video output terminal.

In the above-mentioned video signal recording / reproducing apparatus, instead of inputting only the luminance signal of the output of the recording / reproducing system circuit to the GC circuit, the composite signal output of the recording / reproducing system circuit is sent to the GC circuit. The output from the GC circuit may be led to a video output terminal.

Further, the GC circuit may not be built in the recording / reproducing apparatus, but may be built in the TV receiver, and the output of the recording / reproducing apparatus may be input to the TV receiver as an external input.

Further, the GC circuit is not provided in the recording / reproducing apparatus or the TV receiver, and the output of the recording / reproducing apparatus and the T
It may be connected as an adapter during the input of the V receiver.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The ghost elimination and frequency characteristic improvement method of the present invention not only eliminates ghosts contained in a TV reception image by using an existing GCR (ghost cancel reference) signal, but also eliminates ghosts already recorded. The ghost cancellation is also performed at the time of reproduction of the reproduced data, and the image quality is improved by controlling the frequency characteristics.

First, the GCR currently used in Japan
The signal is shown in FIG. This signal is a signal containing Sinx / x, and the television broadcast station inserts this signal into the 18th line of the TV signal and broadcasts it.

The television receiving side cancels the ghost by controlling this waveform in the received TV signal so as to match the reference signal in the GC (ghost canceling) circuit.

Next, with reference to FIG. 1, a description will be given of a ghost elimination and frequency characteristic correction method of the present invention and a system configuration in a case where the method is applied to a recording / reproducing apparatus such as a VTR.

The video signal of the channel received by the antenna 1 and selected by the tuner 2 is sent to the GC circuit 4 after passing through the input switching circuit 3.

The ghost is removed by the GC circuit 4, and the resulting ghost-free video signal is sent to the display and viewed as it is, or sent to the recording / reproducing circuit 7 via the YC separation circuit 5. It is recorded on the recording medium 8.

The GC circuit 4 is configured as shown in the block diagram of FIG. The baseband video (video) signal is A
It is digitized by the / D converter 12, and a digital filter 13 forms a filter having a characteristic opposite to that of the ghost based on the GCR (ghost cancel reference signal) to perform the ghost cancellation. This GC circuit can be constituted by an IC circuit.

The digital filter is also used to correct the video frequency characteristics. The output of the digital filter 13 is returned to the baseband signal by the D / A converter 14 and output to the output of the GCR circuit. Up to this point, it is the same as the ghost cancellation at the time of receiving the existing TV broadcast.

The ghost canceling and frequency characteristic improvement method of the present invention performs ghost removal and image quality improvement by passing through a GC circuit even during reproduction.
This will be described with reference to FIG.

Only the luminance signal (Y signal) among the reproduced signals output from the recording / reproducing circuit 7 is input to the GC circuit 4, and ghost cancellation is performed on a recorded material that has not been ghost canceled during recording. Further, the frequency characteristics of the reproduced image are optimized by using the waveform equalization performed in the process.

The Y signal sent from the GC circuit is output to a video output after the noise is reduced by the noise reduction circuit 9. The C signal sent from the recording / reproducing circuit 7 is time-aligned with the Y signal by the delay circuit 10 and then output to the video output. On the other hand, the noise reduction circuit 9
And the C signal from the delay circuit 10 are mixed by the YC mixing circuit 11 and output as a composite signal.

FIG. 4 shows an example of the optimal frequency characteristic for the normal VHS, and FIG. 5 shows an example of the optimal frequency characteristic for the super VHS. As shown in this figure, the optimum characteristics for viewing differ depending on the format and the tape speed. Therefore, the present invention automatically adjusts to these optimum characteristics by equalizing the waveform using a GCR signal. This is one function of the circuit.

As for a plurality of characteristic data serving as a reference, reference waveform data may be stored in the GC circuit chip 4 or data may be downloaded from an external control device.

Further, in actuality, the optimum characteristics differ depending on the signal state (brightness or the like) of the tape to be reproduced.
The characteristics may be adaptively controlled according to these conditions. To change the characteristics depending on the brightness, an image signal level detection device is required. This level detection uses an AD converter in the GC circuit 4 and if the level is detected,
It can be realized relatively inexpensively.

As a specific processing method of the luminance signal, Y
By capturing a GCR signal before a reproduced image signal processing circuit such as an NR (Y signal noise elimination) circuit, the GCR signal is extracted with good quality, and the waveform equalization accuracy is improved.

The chrominance signal is time-aligned with the luminance signal using the delay circuit 10, and then mixed with the luminance signal by the YC mixing circuit 11 and output, or output as it is in a state separate from the luminance signal. . The cost can be reduced by incorporating the delay circuit on the same chip as the digital filter for GC.

FIG. 6 is a system block diagram showing another embodiment of a video signal recording / reproducing apparatus to which the ghost signal removal and frequency characteristic correction method of the present invention is applied. The difference from the system shown in FIG. 1 is that the composite signal output from the recording / reproducing circuit 7 (the Y signal and the C signal are not separated).
Is directly input to the GC circuit.

The correction error of the GC circuit is reduced by the method described later, and in particular, the abnormalities (color spots and the like) of the color signal due to the error are suppressed, so that the reproduced signal can be converted into a composite signal as shown in FIG. To perform signal processing. This method is effective in the case of an external format such as an adapter described later.

According to the method of removing a ghost signal and improving the frequency characteristic of the present invention, the insertion circuit 6 shown in FIG.
A signal or a signal enabling control of a new reproduction frequency characteristic is inserted and recorded in a video signal in which a GCR signal is not inserted, or even if a GCR signal is present,
In order to improve the accuracy, the signal is replaced with another signal, and frequency characteristics control during reproduction is performed based on this signal.

As an example of the signal used in this case, there is a U.S. system GCR signal shown in FIG. This is because the energy of the reference frequency signal component is larger and the S / N ratio is improved as compared with the method of Japan, so that the comparison error of ghost removal and waveform equalization is reduced, and further, highly accurate operation becomes possible. is there.

FIG. 1 shows a recording / playback apparatus (a VTR in this example).
FIG. 8 is an example of a ghost canceling and frequency characteristic adjustment circuit built in a TV receiver. As another example of the present invention, a system block diagram in a case where a GC circuit is mounted on a TV receiver is shown in FIG.
Shown in

The system shown in the figure consists of two parts. That is, the TV (television) receiver 15 and the VTR
(Video tape recorder) 22. This TV receiver 15 differs from a conventional GCR-compatible TV receiver in that it has an input switching circuit 18.

That is, the system configuration of the conventional GCR-compatible TV receiver is such that the video signal of the channel which enters from the antenna 16 and is tuned and received by the tuner 17 is sent to the GC circuit 19 where the ghost cancel is performed, and the encoder 20 and the The display is made using the display 21.

On the other hand, in the TV receiver 15 to which the present invention is applied, the input switching circuit 18 is provided in front of the GC circuit, the GC circuit 19 is changed, and an external VTR (video tape recorder) 22 and the like are provided. Can be switched and input with a signal supplied from the PC.

The VTR 22 records a TV image received using the antenna 23 and the tuner 24 on a recording medium through a recording / reproducing circuit 25, and reproduces and outputs a signal recorded on a recording medium 26 by the recording / reproducing circuit 25. It has become.

The output from the VTR includes an AV control signal in addition to an information signal such as a video signal. AV control signal is VTR
The optimum frequency characteristic parameter is provided in accordance with the conditions such as the reproduction tape speed, recording format, and reproduced video amplitude in the above, and the circuit characteristics of the GC circuit are switched according to this parameter.

The information signal output of the recording / reproducing circuit 25 is supplied as an external input to an external input terminal of the TV receiver 15, and is input from the input switching circuit 18 to the TV receiving system. The AV control signal from the recording / reproducing circuit 25 is input to an input terminal for an AV control signal of the TV receiver, and is supplied to the GC circuit 19 through a bus or the like.

As described above, the signal recorded by the receiving tuner 24 by the antenna 23 and received by the tuner 24 and recorded on the recording medium 26 through the recording / reproducing circuit 25 is also switched from the recording / reproducing circuit 25 to the input of the TV receiver during reproduction. The signal is sent to the circuit 18, the ghost is canceled and the frequency characteristic is corrected by the GC circuit 19, and can be displayed on the display 21.

Next, as another embodiment of the ghost removal and frequency characteristic adjustment method of the present invention, a case where the GC circuit is constituted by an external adapter of a VTR will be described with reference to FIG.

Comparing the system configurations of the present embodiment and the embodiment shown in FIG. 8, the output of the VTR is input to the GCR-compatible TV receiver in the embodiment shown in FIG. Is supplied to a conventional TV receiver or monitor that does not support GCR via an adapter 32 having a GC circuit.

One operation mode of the present system is to operate in the same manner as a normal TV receiver. That is, V
In the TR 27, the video signal received on the path of the antenna 28 and the tuner 29 is sent to the recording / reproducing circuit 30, from which V
It is sent to the external adapter 32 as the output of the TR 27.

The adapter 32 has a built-in GC circuit 33, controls the GC circuit by an AV control signal sent from the recording / reproducing circuit 30, corrects the signal, and outputs the corrected signal to the TV receiver or the monitor 34. Then, it is displayed on the display 35.

Another operation mode of the present system is an operation mode as a VTR. The television broadcast signal received on the path of the antenna 28 and the tuner 29 is recorded on a recording medium 31 through a recording / reproducing circuit 30. The signal recorded on the recording medium is reproduced by the recording / reproducing circuit 30 and sent to the adapter 32. After performing ghost cancellation and frequency characteristic correction, the signal is sent to the TV receiver or monitor and displayed there.

The circuit characteristics of the GC circuit 33 in the adapter 32 are controlled by a signal such as an AV control signal sent from the VTR, so that the type of the input video signal (TV reception video or recording medium playback video, etc.) is controlled. It is changed so that the frequency characteristics are optimal.

In order to improve the accuracy of the frequency characteristic control,
As a method of preventing the deterioration of the GCR signal by the signal processing accompanying the recording and reproduction of the video, in addition to the above-described method of taking in the GCR signal before the reproduced image signal processing circuit such as the YNR circuit 9 in FIG. It is even more effective if YC separation is devised.

As the YC separation method, there are a band separation method, a three-line YC separation method, a three-dimensional YC separation method, and the like.
It is effective to avoid a change in signal phase and an influence from an adjacent scanning line.

FIG. 10 shows a configuration example of a general three-line YC separation circuit. 1H (one horizontal period) delay lines 36 and 37
The signal before 1H, the current signal, and the signal after 1H created by the above are input to the arithmetic unit 38, and the output is input to the color signal band BP.
A color signal is extracted through an F (band-pass filter) 39 and output to C _out .

Further, the current signal is transferred to a delay line 4 for time alignment.
After passing the signal through 0, the signal is input to the arithmetic unit 41, the chrominance signal is removed from the signal, a luminance signal is extracted and output to _Yout .

Here, when the calculation is performed by the calculator 38, the signal components of the preceding and succeeding scanning lines affect the GCR signal.
In the vicinity of the position where the scanning line of the CR signal exists, the operation in the arithmetic unit 41 is stopped to avoid this influence.

FIG. 11 shows an example of a signal for controlling the arithmetic unit 41. As shown in the figure, the period during which the Y signal separation is stopped is the portion of the 18th line of the vertical blanking period in 1 V (one vertical period).

For example, those already recorded on conventional equipment,
During recording, it is affected by adjacent lines due to YC separation,
If any noise has been superimposed on the GCR signal, randomness noise can be obtained by increasing the GCR signal extraction time and taking the average characteristic when referencing the GCR signal shown in FIG. Reduce the effects of

[0061]

According to the present invention, if a GCR signal remains even in a video already recorded with a ghost, the ghost can be removed. -Images recorded in any situation can be adjusted to the optimal frequency characteristics. By providing an absolute reference for the frequency characteristic, it is possible to control the absolute value of the frequency characteristic.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a recording / playback apparatus equipped with a ghost cancellation and frequency characteristic adjustment circuit.

FIG. 2 is a conceptual diagram of a GCR signal used in Japan.

FIG. 3 is a block diagram illustrating a configuration example of a GCR signal processing circuit.

FIG. 4 is a characteristic diagram illustrating an example of reference characteristics of a GC circuit.

FIG. 5 is a characteristic diagram showing another example of the reference characteristic of the GC circuit.

FIG. 6 is a block diagram of another example of a recording / playback apparatus equipped with a ghost cancellation and frequency characteristic adjustment circuit.

FIG. 7 is a conceptual diagram of a GCR signal used in the United States.

FIG. 8 is a system block diagram of an embodiment in which a GC circuit is built in a TV receiver.

FIG. 9 is a system block diagram of an embodiment in which a GC circuit is configured as an external adapter.

FIG. 10 is a circuit block diagram of a configuration example of a three-line YC separation circuit.

FIG. 11 is a waveform diagram of a YC separation operation control signal.

FIG. 12 is a block diagram of an example of a conventional GCR-compatible recording / playback device.

[Explanation of symbols]

1 antenna, 2 TV tuner, 4 GC circuit chip, 5 YC separation circuit, 6 signal insertion circuit, 7
{Recording / playback circuit, 8} Recording medium, 9} Signal processing circuit (YNR, etc.), 10} Delay circuit, 11} YC mixed circuit

Claims (12)

[Claims] 1. A video signal input circuit including a TV broadcast receiving circuit, an external input terminal, and an input switching circuit for switching between them, and a GCR included in a video signal transmitted from the video signal input circuit. Ghost cancellation and / or signal detection
Or a GC that corrects the frequency characteristics and outputs the result
A circuit that separates the output of the GC circuit into a luminance signal and a chrominance signal, attaches a GCR signal to the luminance signal, and sends the luminance signal and the chrominance signal to the recording and reproduction system circuit; A video signal recording / reproducing apparatus comprising: a circuit for sending to a GC circuit; and an output system circuit for adjusting the time of a luminance signal output from the GC circuit and a color signal output from a recording / reproducing system circuit to output to a video output terminal. 2. The video signal recording and reproducing apparatus according to claim 1, wherein a GC circuit and a GCR signal insertion circuit are formed on the same IC chip. 3. The video signal recording / reproducing apparatus according to claim 2, wherein the time alignment of the luminance signal and the chrominance signal is performed by a delay circuit provided in a chrominance signal circuit.
A video signal recording / reproducing device formed by a digital filter in the same chip as the circuit. 4. The video signal recording / reproducing apparatus according to claim 1, wherein a noise reduction circuit is provided in a Y signal transmission path of the output system circuit, and extraction of a GCR signal is performed by a GC circuit before the noise reduction circuit. A video signal recording / reproducing apparatus capable of taking out a GCR signal in a good condition. 5. A video signal input circuit including a TV broadcast receiving circuit, an external input terminal, and an input switching circuit for switching between them, and a GCR included in a video signal sent from the video signal input circuit. Ghost cancellation and / or signal detection
Or a GC that corrects the frequency characteristics and outputs the result
A circuit for dividing the output of the GC circuit into a luminance signal and a chrominance signal, attaching a GCR signal to the luminance signal, and sending the luminance signal and the chrominance signal to the recording / reproducing system circuit, and a composite signal output of the recording / reproducing system circuit A video signal recording / reproducing apparatus, comprising: a circuit for sending a signal to a GC circuit; and a circuit for guiding an output from the GC circuit to a video output terminal. 6. The video signal recording / reproducing apparatus according to claim 5, wherein a GC circuit is used to reduce a correction error of the GC circuit.
A video signal recording / reproducing apparatus in which the reference time of the R signal is extended. 7. The video signal recording / reproducing device according to claim 1, wherein the YC separation function is stopped during a certain period of the GCR signal so that the GCR signal is not damaged by the YC separation circuit at the time of recording. Video signal recording and playback device. 8. The video signal recording / reproducing apparatus according to claim 1, wherein a GCR signal of another system such as the United States or Korea or a signal capable of controlling other frequency characteristics is used to reduce a correction error. A video signal recording / reproducing device to be replaced. 9. A recording / reproducing apparatus including a TV broadcast receiving system circuit, a recording / reproducing system circuit, an external output terminal from the recording / reproducing system circuit and an AV control signal output terminal, a TV broadcast receiving system circuit, an external input terminal, and an input. A TV receiver comprising a pre-stage circuit including a switching circuit, a GC circuit, an AV control signal input terminal, and a post-stage circuit including a display device; and an external output terminal and an AV control signal output terminal of the recording / reproducing apparatus. A video signal recording / reproducing apparatus which is connected to an external input terminal and an AV control signal input terminal of the TV receiver and reproduces and displays an output of the recording / reproducing apparatus through a GC circuit built in the TV receiver. 10. A recording / reproducing apparatus including a TV broadcast receiving system circuit, a recording / reproducing system circuit provided at a subsequent stage, an external output terminal from the recording / reproducing system circuit, and an AV control signal output terminal. A video signal recording / reproducing apparatus comprising: an adapter including a GC circuit to which a video signal and an AV control signal are applied from an external output terminal and an AV control signal output terminal; and a TV receiver or a monitor connected after the adapter. . 11. The video signal recording / reproducing apparatus according to claim 9, wherein a ghost cancel of a reproduced image is performed using a GCR signal included in a reproduced signal output from a recording / reproducing system circuit. Signal recording / reproducing device. 12. The video signal recording / reproducing apparatus according to claim 9 or 10, further comprising, as parameters, optimal frequency characteristics according to a reproduction tape speed, a recording format, a reproduced video amplitude, and the like given by the AV control signal.
A video signal recording / reproducing device which is switched as necessary to obtain optimum characteristics.