JPH06197374A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the waveform reproducibility of a reinforced signal portion when a television signal of a letter box system with a reinforcement signal multiplexed thereon is recorded/reproduced by a home use VTR or the like. CONSTITUTION:The device is provided with a reinforcement signal period detection circuit 30 identifying a letter box system television signal and detecting a horizontal valid period of the reinforcement signal of the video signal of the letter box system. Then the operation of a YC separator circuit 31 separating YC of a video signal to be recorded is stopped for the reinforcement period and the signal is processed as the luminance signal for this period. Thus, since the reinforcement signal is not subjected to low frequency conversion as a color difference signal, the deterioration in the frequency characteristic is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing apparatus used for recording / reproducing a video signal.

[0002]

2. Description of the Related Art Conventionally, in Japan, the broadcasting system of television signals is based on the NTSC system, and the aspect ratio of the screen is 4: 3, the number of scanning lines is 525, and the image is distributed by the 2: 1 interlace system. Has been done. In recent years, the government and the private sector have been working together on research and development to transmit non-interlaced images with a screen aspect ratio of 16: 9 and 525 scanning lines, while the signal form remains fully compatible with the NTSC system. Has been. Recently, it was decided that this new broadcasting system would be the letterbox system.

In the letterbox system, the conventional about 480
Of the effective scanning lines, 360 in the central portion transmits a 16: 9 landscape screen, and the remaining 120 in the upper and lower portions are used to transmit signals and motion information that reinforces the deterioration of vertical resolution. . When this broadcast is received by a dedicated television set, by decoding the reinforcement signal, it is possible to restore a high quality image with an aspect ratio of 16: 9, which is higher than conventional images.

However, when a new broadcast is received by a conventional television set having an aspect ratio of 4: 3,
Since the enhancement signal is not decoded, the image that can be seen is only about 360 signals in the central portion. Since the upper and lower reinforcement signals are signals different from the conventional NTSC system, this portion will be erroneously demodulated.

In a consumer VTR such as the conventional VHS system, such a new form of signal is not assumed as a recording signal. Therefore, a new signal is sent to the conventional consumer V
In the case of recording / reproducing in TR, the scanning lines in the upper and lower portions of the screen, which is a new signal form, are processed by the same signal processing circuit as before and recorded. ("Video Technology Handbook" published by Denpa Shimbun, p.76, complete diagram of home video signal processing system)

An example of a conventional video signal recording / reproducing apparatus will be described below with reference to the drawings. Conventional VHS
FIG. 5 shows a block diagram of a video signal recording / reproducing apparatus of the SVHS system or the SVHS system. In FIG. 5, a video signal (NTSC signal) is input to the input terminal 1. The video signal input from the input terminal 1 is first separated into a luminance signal and a color difference signal by the YC separation circuit 2. The separated luminance signal Y is limited to a predetermined signal band (about 3 MHz in the VHS system and about 5 MHz in the SVHS system) by the low-pass filter (LPF) 3, and then the high frequency component is emphasized by the emphasis circuit 4. . Then, the clipping circuit 5 clips the white peak and the black peak to a predetermined level,
Obtain a signal whose signal amplitude is within a certain dynamic range. This signal is FM-modulated by the next FM modulation circuit 6, band-limited to a predetermined signal band by a band-pass filter (BPF) 7, and the processing of the luminance signal ends.

On the other hand, the color difference signals separated by the YC separation circuit 2 are sub-carriers 3.
After being limited to the upper and lower bands of about 500 KHz around 58 MHz, the low band conversion circuit 9 performs low band conversion so that the subcarrier becomes 629 KHz.

The low-pass converted color difference signal and the FM-modulated luminance signal are added by the adder 10 to form a frequency-multiplexed recording video signal. Then, it is amplified by the recording amplifier 11 so as to have an optimum level for the tape-head system, and recorded on the magnetic tape 13 by the recording head 12.

The video signal recorded on the magnetic tape 13 is
At the time of reproduction, it is read by the reproduction head 14 and reproduced by the reproduction amplifier 1.
After being amplified to a predetermined level in 5, the high-pass filter (HPF) 16 and the low-pass filter 17 separate the luminance signal and the chrominance signal, and the respective reproduction signal processing is performed.

The amplitude of the separated luminance signal is limited by the limiter circuit 18 for FM demodulation, and is applied to the FM demodulation circuit 19. The signal demodulated by the FM demodulation circuit 19 is accompanied by triangular noise peculiar to FM transmission, and this noise is suppressed by the de-emphasis circuit 20 while suppressing the signal high frequency component. In this way, the distortion component is reduced, the signal-to-noise ratio (SNR) is improved, and the luminance signal is demodulated. Regarding the color difference signal, the sub-carrier wave 62 of the color difference signal is processed by the high frequency conversion circuit 21 contrary to the recording operation.
9 KHz is converted to the original 3.58 MHz. Then, it is added with the luminance signal demodulated by the adder 22 to form a reproduced video signal, which is output from the output terminal 23.

[0011]

In such a conventional consumer video signal magnetic recording / reproducing apparatus, the current video signal as shown in FIG. 6 (a) can be recorded / reproduced. However, in the new letterbox system broadcasting,
Reinforcement signals are sent by 120 scanning lines at the top and bottom of the screen as shown in FIG. 6B. VHS method (S
In a consumer video signal recording / reproducing apparatus such as the VHS system), an input video signal is first separated into a luminance signal and a color difference signal by a YC separation circuit, and different processing is applied to each. The color difference signal originally transmitted by the NTSC system has a band of about 1.5 MHz, but VHS (SVHS)
Frequency of the subcarrier converted to low frequency by the method H629KHz
However, since the magnetic recording / reproducing system cannot transmit a component in the vicinity of direct current, recording / reproducing is performed only in a band of about 400 KHz. A comb filter is usually used for the YC separation circuit, and the low frequency component and the line correlation high frequency component of the video signal are used as the luminance signal, and the line non-correlation high frequency component is used as the color difference signal.

When this processing is performed on the reinforcement signal portion having a signal form different from that of the conventional signal, the line non-correlation high frequency component of the reinforcement signal which is not originally the color difference signal is processed as the color difference signal. . Therefore, the line uncorrelated high frequency component of the reinforcement signal cannot be properly recorded and reproduced. If such a distorted reinforcement signal is transmitted to a dedicated decoder of the letterbox system, the decoder cannot perform its original operation, and the reinforcement signal to be used for improving the image quality causes a deterioration in image quality. There was a problem.

The present invention solves the above-mentioned problems by providing V
It is an object of the present invention to obtain a recording / reproducing apparatus, such as an HS (SVHS) system, which converts a color difference signal into a low frequency band and which can record / reproduce a reinforcing signal in a form that is as faithful to the original signal as possible with a simple configuration.

[0014]

SUMMARY OF THE INVENTION According to the present invention, a video signal to be recorded is input and a letterbox type video signal is discriminated from a normal video signal. A reinforcement signal period detection circuit that detects the effective period and outputs a YC separation control signal, a color difference signal processing circuit unit that converts a color difference signal of a video signal to be recorded into a low frequency range, a luminance signal is FM-modulated, and a color difference signal A luminance signal processing circuit section for adding and outputting to the output of the processing circuit section, a video signal to be recorded is separated into a luminance signal and a color difference signal, the luminance signal is a luminance signal processing circuit section, and the color difference signal is a color difference signal processing circuit. And a YC separation circuit for inputting the video signal to the luminance signal processing circuit section and stopping the signal separation when the YC separation control signal from the reinforcement signal period detection circuit is obtained. By the signal processing circuit unit is characterized in that it has a, a reproducing circuit for reproducing a signal recorded on the recording medium.

[0015]

According to the present invention having such characteristics, whether or not the input video signal is a letterbox type video signal is first discriminated by the reinforcement signal period detection circuit, and in the case of a letterbox type video signal, the reinforcement is performed. The signal of the horizontal effective period of the signal is output. The operation of the YC separation circuit that separates the video signal into the luminance signal and the color difference signal is stopped only during the reinforcement signal period, and during this period, all the input signals are input to the luminance signal processing system and recorded. In this case, the reinforcement signal is converted to the low frequency range and is not recorded, so that the frequency characteristics and the waveform reproducibility of the reinforcement signal are improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of a video signal magnetic recording / reproducing apparatus according to an embodiment of the present invention.
In this figure, the same parts as those of the conventional example described above are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, the reinforcing signal period detection circuit 30 and the YC separation circuit 31 are connected to the input terminal 1. The reinforcement signal period detection circuit 30 is a circuit for detecting the reinforcement period of the video signal transmitted by the letterbox system as shown in FIG. 5B, and its output is supplied to the YC separation circuit 31 as a YC separation control signal. Given. The YC separation circuit 31 performs normal YC separation when the control signal is at the L level, and supplies the luminance signal to the low pass filter 3 and the color difference signal to the band pass filter 8. This YC separation control signal is H
When it is at the level, YC separation is not performed, and the video signal input to the input terminal 1 is given to the low-pass filter 3 as it is,
This is a circuit that prohibits output to the high-pass filter 8. The circuit configurations of the low-pass filter 3 and the band-pass filter 8 and onward are the same as those of the conventional example described above, and thus detailed description thereof will be omitted. Here, the low pass filter 3, the emphasis circuit 4, the clipping circuit 5, the FM modulation circuit 6, the band pass filter 7, the adder circuit 10 and the recording amplifier 11,
Each block up to the recording head 12 constitutes a luminance signal processing circuit unit that FM-modulates the luminance signal and adds the color difference signal to record, and the band pass filter 8 and the low frequency conversion circuit 9 reduce the color difference signal. A color-difference signal processing circuit unit that performs area conversion is configured. Each block from the reproducing head 14 to the adder circuit 22 constitutes a reproducing circuit section for reproducing the signal recorded on the recording medium.

FIG. 2 is a block diagram showing a detailed structure of the reinforcement signal period detection circuit 30. In the figure, a sync signal separation circuit 32 is connected to the input terminal 1. The sync signal separation circuit 32 is composed of a sync separation circuit 32a for separating horizontal and vertical sync signals of an input signal, a vertical sync separation circuit 32b for separating a vertical sync signal from its output, and an equalization pulse removal circuit 32c. . The vertical sync separation circuit 32b outputs a vertical sync signal. The equalization pulse removal circuit 32c outputs a horizontal synchronization signal by removing the equalization pulse portion from the synchronization separation circuit, and its output is given to the counter circuit 33 and the horizontal effective period detection circuit 34. Further, the vertical synchronizing signal is output as a reset signal to the counter circuit 33. The counter circuit 33 detects the horizontal synchronizing signals to detect the 60 reinforcing signal portions above and below each screen. The horizontal effective period detection circuit 34 detects the horizontal effective period of the video signal excluding the synchronizing signal and the burst signal based on the horizontal synchronizing signal, and the outputs thereof are given to the AND circuit 35. The system identification circuit 3 is provided for the input terminal 1.
6 is connected. The system discrimination circuit 36 discriminates between a normal video signal and a letterbox system video signal, and in the case of the letterbox system, an AND circuit 35 outputs an H level discrimination signal.
To give to. The AND circuit 35 uses these logical product outputs as YC separation control signals.
It is given to 1.

Next, the operation of this embodiment will be described with reference to the time charts of FIGS. First, when a letter box type video signal is applied to the input terminal 1 as shown in FIGS. 3 and 4A, the reinforcement signal period detection circuit 30
This signal is identified by the system identification circuit 36 in.
Then, the sync separation circuit 32a in the sync signal separation circuit 32 outputs the horizontal sync signal (b) and the vertical sync signal (c) as shown in FIGS. Since this signal is given to the counter circuit 33 and the horizontal effective period detection circuit 34, the counter circuit 33 outputs a signal indicating the reinforcement period as shown in FIGS. 3 and 4D. Similarly, the horizontal effective period detection circuit 34 outputs a signal indicating the effective period of the video signal as shown in FIGS. 3 and 4E.
Then, in the AND circuit 35, the YC separation control signal shown in FIG. 3 and FIG.
It is given to the separation circuit 31. In this way, YC separation is not performed when the YC separation control signal is at H level, and all video signals are added to the low pass filter 3. YC
Since the recording and reproducing operations after the separation are the same as those of the conventional example, detailed description will be omitted. This prevents the conventional color difference signal low frequency conversion type recording / reproducing apparatus from erroneously converting the horizontal high frequency component and the vertical high frequency component of the reinforcement signal into the color difference signal for low frequency conversion, and processing as a luminance signal. Is made.
Therefore, frequency characteristics and waveform reproducibility are improved.

Although the present embodiment has been described with respect to the magnetic recording / reproducing apparatus, it can be similarly applied to a video signal recording / reproducing apparatus using light.

[0020]

As described in detail above, according to the present invention, when a signal having a reinforcement signal period such as a letterbox system is input to a color difference signal low frequency conversion type recording / reproducing apparatus, a reinforcement signal portion is input. Are all processed as luminance signals. Therefore, the deterioration of the frequency characteristic due to the low-frequency conversion of the color difference signal can be avoided, and the reinforcement signal with good waveform reproducibility can be obtained. In this way, by adding a simple circuit to a normal recording / reproducing apparatus, it is possible to record / reproduce a letterbox type signal as a conventional signal in the same manner.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a reinforcement signal period detection circuit 30 according to the present embodiment.

FIG. 3 is a time chart (No. 1) showing the operation of the reinforcement signal period detection circuit according to the present embodiment.

FIG. 4 is a time chart (No. 2) showing the operation of the reinforcement signal period detection circuit according to the present embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional magnetic recording / reproducing apparatus.

FIG. 6 is a conceptual diagram of a letterbox method and a normal method.

[Explanation of symbols]

 1 Input Terminal 2,31 YC Separation Circuit 3,17 Low Pass Filter 4 Emphasis Circuit 5 Clipping Circuit 6 FM Modulation Circuit 7,8 Band Pass Filter 9 Low Band Conversion Circuit 10,22 Adder 11 Recording Amplifier 12 Recording Head 13 Magnetic Tape 14 Playback head 15 playback amplifier 16 high-pass filter 18 limiter circuit 19 FM demodulation circuit 20 de-emphasis circuit 21 high frequency conversion circuit 23 output terminal 30 reinforcing signal period detection circuit 32 sync signal separation circuit 32a sync separation circuit 32b vertical sync separation circuit 32c equalization Pulse removal circuit 33 Counter circuit 34 Horizontal effective period detection circuit 35 AND circuit 36 Method identification circuit

Claims (1)

[Claims] 1. A video signal to be recorded is input, and a letterbox video signal and a normal video signal are discriminated.
In the case of a letterbox type video signal, the reinforcement signal period detection circuit that detects the horizontal effective period of the reinforcement signal and outputs the YC separation control signal, and the color difference signal processing that converts the color difference signal of the video signal to be recorded into the low frequency range A circuit section, a brightness signal processing circuit section for FM-modulating a brightness signal, adding the result to the output of the color difference signal processing circuit section and recording, and separating a video signal to be recorded into a brightness signal and a color difference signal,
A luminance signal is given to the luminance signal processing circuit section and a color difference signal is given to the color difference signal processing circuit section, and when the YC separation control signal from the reinforcement signal period detection circuit is obtained, the signal separation is stopped and the video signal is displayed. A video signal recording / reproducing apparatus comprising: a YC separation circuit input to a luminance signal processing circuit unit; and a reproducing circuit unit reproducing a signal recorded on a recording medium by the luminance signal processing circuit unit.