JP2986169B2 - Video signal recording and playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing apparatus provided with a residual color signal removing means for removing a residual color signal from a reproduced video luminance signal.

2. Description of the Related Art In recent years, video signal recording / reproducing apparatuses, for example, in an S-VHS video cassette recorder, if the separation of a luminance signal and a color signal of a composite video signal is incomplete, a color signal remains in the luminance signal. It is recorded in the state where it was done. When this video signal is reproduced, a beat is generated due to interference between the color signal remaining in the reproduction luminance signal and the color signal reproduced from the color signal reproduction system, thereby deteriorating the image quality.

In order to prevent this, some luminance signal reproducing circuits have a color signal trap circuit for removing a residual color signal.

Hereinafter, the above-described conventional video signal recording / reproducing apparatus will be described with reference to the drawings.

FIG. 3 shows a block diagram of a conventional video signal recording / reproducing apparatus. In FIG. 3, 1 is a porcelain head, and 2 is a head amplifier for amplifying a signal induced by the porcelain head 1. Reference numeral 3 denotes a color signal reproduction circuit for reproducing the recorded color signal, 4 denotes a luminance signal reproduction circuit for reproducing the recorded luminance signal, and 5 denotes a color signal remaining in the reproduced luminance signal. Is a color signal trap circuit composed of traps resonating at the color width carrier frequency. Reference numeral 6 denotes a switch which is manually operated, and switches between the output of the color signal trapping circuit 5 and the output of the luminance signal reproducing circuit 4. Reference numeral 7 denotes an adder, which adds the output of the color signal reproducing circuit 3 and the output of the switch 6 to output a reproduced video signal.

The operation of the conventional video signal recording / reproducing apparatus configured as described above will be described below.

In a normal use state, the switch 6 is connected to the Y side,
The color signal output from the color signal reproduction circuit 3 and the luminance signal output from the luminance signal reproduction circuit 4 are added by an adder 7 to output a reproduced video signal.

Next, when the color signal remains in the luminance signal output from the luminance signal reproducing circuit 4, the switch 6 is connected to the Y side in the normal state, so that the color signal and the color signal remaining in the luminance signal remain. Signals interfere to generate beats. At this time, the luminance signal passes through the color signal trap circuit 5 by manually switching the switch 6 and connecting to the X side, whereby the luminance signal from which the residual color signal has been removed is added to the color signal by the adder 7. Thus, a reproduced video signal without a beat is obtained.

However, in the above-described conventional configuration, when a beat occurs in the reproduced video signal output, the switch 6 must be manually operated. In addition, the switch 6 is used for manual operation.
Remains connected to the X side, the reproduced luminance signal always passes through the color signal trapping circuit 5, so that even when the luminance signal output from the luminance signal reproducing circuit 4 does not include the residual color signal, There has been a problem that the frequency characteristics of the signal are reduced and the overall image quality is deteriorated as a result.

SUMMARY OF THE INVENTION An object of the present invention is to provide a video signal recording / reproducing apparatus which solves the above-mentioned conventional problems and automatically removes a beat component without manual operation and does not deteriorate the overall image quality of a reproduced video signal. Things.

Means for Solving the Problems In order to solve the above problems, a video signal recording / reproducing apparatus according to the present invention is provided with a video signal recording / reproducing apparatus which receives a reproduced luminance signal and removes a color signal component remaining in the reproduced luminance signal. Means, a color burst detecting means for detecting a color burst signal remaining in the reproduced luminance signal, and a control signal output from the color burst detecting means for switching between the reproduced luminance signal and the output signal for the residual color signal removing means. Switching means to be controlled.

According to the above arrangement, the color burst detecting means detects the color burst component remaining in the reproduced luminance signal, and the switching means controlled by the control signal output from the color burst detecting means controls the reproduction luminance signal and the residual color signal removing means. Since the output signal is switched according to the presence or absence of the color burst component, the beat component is automatically removed, and the switching means remains operated even when the luminance signal does not include the residual color signal, as in the related art. In addition, the problem that the output signal of the residual color signal removing means is selected and the overall image quality is deteriorated can be solved.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a video signal recording and reproducing apparatus according to an embodiment of the present invention. 11 is a color burst detection circuit. 12 is a horizontal sync separation circuit for separating the horizontal sync signal from the reproduced video signal, 13 is a burst separation pulse generation circuit that outputs a pulse at the timing of the burst position of the composite signal, and 14 is a band pass that passes the color width carrier frequency Filter (hereinafter referred to as BPF), 15 is an amplification circuit, 16 is a detection circuit, 17 is an integration circuit, 18
Is a voltage comparator that compares the output of the reference power supply 19 with the output of the integrator 17;
Reference numeral 20 denotes a switch which closes when the control signal becomes H level.
A switch 21 selects the X side when the control signal becomes H level.

 The operation of the above configuration will be described below.

FIG. 2 is a waveform diagram showing an output waveform in each main part of FIG.

The reproduced luminance signal A output from the luminance signal reproducing circuit 4 is input to the horizontal synchronizing separation circuit 12, and the horizontal synchronizing signal a shown in FIG. 2A is separated, and the output signal B shown in FIG.
Output. Further, the output signal B from the horizontal synchronization separation circuit 12 is input to the burst separation pulse generation circuit 13, and the burst separation pulse C is output. During the burst separation pulse C, the switch 20 is closed.

First, as shown in the second part (a), when the reproduced luminance signal A1 output from the luminance signal reproducing circuit 4 includes the residual color signals b1 and b2, the switching unit 20 controls the residual color burst. The component b1 is extracted, and a signal D shown in FIG. 2D, which is the output of the BPF 14, is obtained. This signal D is amplified by the amplifier circuit 15 to become the signal E in FIG. 2 (e), which is input to the detection circuit 16 and becomes the detection circuit output signal F shown in FIG. 2 (f). This output signal F is input to the integration circuit 17, and the DC component G1 of FIG. 2 (g) corresponding to the level of the residual color burst component b1 is input to the + terminal of the voltage comparator 28. Here, the reference voltage _VA of the reference power supply 19 is indicated by a dotted line _VA in FIG. 2 (g), and is set to a voltage which is a threshold value at which it can be determined that the residual color burst component is included. In this case, the control output from the voltage comparator 18 becomes high level as shown by a signal H1 in FIG. 2 (h), and the switch 21 is switched to the X side to select the output of the color signal trap circuit 5. . The luminance signal I1 as shown in FIG. 2 (i) from which the residual color signal has been removed is input to the adder 7.

Next, as shown in FIG. 2 (a), when the reproduced luminance signal A2 output from the luminance signal reproducing circuit 4 does not include the residual color signal, as shown in FIG. 2 (g), The DC component G2 output from the integration circuit 17 is the reference voltage of the reference power supply 19.
Since it is smaller than V _A, the control output from the voltage comparator 18 becomes low level as shown by the signal H2 in FIG.
The switch 21 is switched to the Y side to select the output of the luminance signal reproducing circuit 4. The adder 7 has a luminance signal reproducing circuit 4
The luminance signal A2 (I2), which is the output of, is input. here,
It is necessary to determine an appropriate value for the reference voltage _{VA according} to the performance of the device.

As described above, by providing the color burst detection circuit 11 as a control signal generation circuit of the switch 21 for selecting and outputting either the output of the luminance signal reproduction circuit 4 or the output of the color signal trap circuit 5, the reproduction luminance signal , The residual color signal can be automatically removed.

In this embodiment, the color signal trapping circuit 5 is used as a circuit for removing the residual color signal, but a comb filter may be used.

Advantageous Effects of the Invention As described above, according to the present invention, it is possible to realize an excellent video signal recording / reproducing apparatus capable of automatically obtaining a high-quality video without a beat component.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video signal recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each main part of FIG. 1, and FIG. 3 is a block diagram of a conventional video signal recording / reproducing apparatus. is there. 5 ... color signal trap circuit, 11 ... color burst detection circuit, 12 ... horizontal sync separation circuit, 13 ... burst separation pulse generation circuit, 14 ... bandpass filter, 15 ...
Amplification circuit, 16 Detector circuit, 17 Integration circuit, 18 Voltage comparator, 19 Reference power supply, 20, 21 Switcher, A, A1, A2
…… Reproduction luminance signal, b ₁ , b ₂ … Residual color signal, b1…
The residual color burst components of the residual color signal, H, H1, H2 ...
... Control output.

Claims (1)

(57) [Claims] 1. A residual color signal removing means for receiving a reproduced luminance signal and removing a color signal component remaining in the reproduced luminance signal, and a color detecting means for detecting a color burst signal remaining in the reproduced luminance signal. Burst detection means;
A video signal recording / reproducing apparatus comprising: switching means for switching between the reproduced luminance signal and the output signal of the residual color signal removing means by a control signal output from the color burst detecting means.