JPH02179189A - Video recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a correct reproducing picture being free from hue irregularities in a TV, etc., by detecting a pilot burst signal component added into a chrominance signal outputted from a chrominance signal reproducing circuit, and erasing a pilot burst signal from the chrominance signal, based on this detection. CONSTITUTION:A horizontal synchronizing signal is taken out by a horizontal synchronizing separator circuit 2, and by allowing a chrominance signal outputted from a chrominance signal reproducing circuit 3 to pass through only a horizontal synchronizing signal period, a pilot burst signal is fetched. Subsequently, a level detection of the pilot burst signal is executed by a detecting circuit 5, it is outputted as a pulse signal, and thereafter, based on the pulse signal, the pilot burst signal is erased by an erasing circuit 6. In such a way, the erasion can be executed surely, a correct reproducing picture being free from hue irregularities is obtained in a TV, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video recording and reproducing apparatus that uses a recording color signal to which a pilot burst signal is added.

BACKGROUND OF THE INVENTION In recent years, video recording and playback devices, especially video tape recorders (
There has been a remarkable improvement in the image quality of VTRs (hereinafter referred to as VTRs).

In order to improve image quality, the method of shifting the frequency of the FM carrier wave of the luminance signal to a higher frequency range is not limited to the NTSC method, but also the PAL method.
This method is also becoming popular.

This high-frequency shifted PAL system adds a pilot burst signal to the recorded special color signal in its format. As shown in Figure 3, the position of the pilot burst signal is 0 from the leading edge of the horizontal synchronous signal to the start of the burst.
, 8±0.3 μs, and the burst length is 2.26
The phase is different from the color burst signal by ±0.23 μs. During playback, necessary information is detected from this pilot burst signal and the subsequent signal processing circuit is switched, but when outputting as a video signal, it is necessary to erase the pilot burst signal added to the horizontal synchronization signal. be. For this reason, conventionally, at the time of necking, a horizontal synchronizing signal was used to generate a pulse signal corresponding to the pilot burst signal period based on this signal, and the pilot burst signal was erased by this pulse signal.

An example of the conventional video recording and reproducing apparatus described above will be described below with reference to the drawings. FIG. 4 is a block diagram of a conventional video recording and reproducing device. In the figure, 11 is a luminance signal reproducing circuit, 12 is a horizontal synchronization separation circuit, and 13.14 is a monostable multivibrator (hereinafter referred to as MM).p, M1vi1
3 has a time constant of 0.8-0.3 μs, for example, and M
MI4 is, for example, 2.26 + 0.23 μs. 16 is a color signal reproducing circuit, 16 is an erasing circuit, 1
7 is a mixing circuit.

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

FIG. 6 shows the signal waveform at nine points from a in FIG. 4. From FIG. 4, first, the luminance signal processing of the reproduction system is performed by the luminance signal reproducing circuit 11 and outputted (FIG. 5a). Next, a horizontal synchronization signal of the luminance signal a is outputted by the horizontal synchronization separation circuit 12 (FIG. 6b), and the MMI 3 operates at the rising edge of this signal based on the horizontal synchronization signal
．． The MMI4 outputs a signal C (Fig. 5) with a pulse period of 8-0.3 μs, and the falling edge of this signal C is 9, which is 2.26.
A pulse signal d (FIG. 5) corresponding to the pilot burst signal period is output with a pulse of +0.23 μs. After the color signal reproduction circuit 15 performs reproduction-related color signal processing,
The signal is output (FIG. 6e), and the erasing circuit 16 performs erasing only during this period using the pulse signal d to remove the pilot burst signal (FIG. 6f). Next, mixing circuit 1
7, the luminance signal a and the color signal f after erasing the pilot burst signal are mixed and output as a video signal (FIG. 6q).

Problem to be Solved by the Invention However, in the above configuration, the pulse signal d corresponding to the pilot burst signal period is
Since the pilot burst signal added to the color signal e is erased based on this pulse signal d, as shown in Fig. 6, the pulse signal d is added to the color signal e. If the period (timing) of the pilot burst signal is the same, the pilot burst signal can be effectively erased (FIG. 6f), but the position at which the pilot burst signal is added varies depending on the recording device. Moreover, the timing of the pulse signal d is also MMla,
In addition to variations in the time constant of MMI 4, the time difference between the luminance signal a and the color signal e also varies depending on the reproduction device.

For this reason, if the period (timing) of the pilot burst signal added to the pulse signal d and color signal e deviates as shown in Fig. 7, there will be a portion where the pilot burst signal cannot be completely erased (Fig. 7 f). ).

Since the pilot burst signal has a different phase from the color burst signal, the color signal f is different from the luminance signal a.
(Fig. 7q), and output as a video signal. Since the TV with a wide burst gate width takes in the pilot burst signal as a color burst signal, the T
At V, a circuit (hereinafter referred to as an APC circuit) that extracts the reference phase of a color signal using a color burst signal malfunctions, and the hue becomes disordered. In addition, even when recording the playback signal of a VTR on another VTR, the AP of the recording VTR is
There was a problem in that the C circuit malfunctioned and the hue was disturbed.

In view of the above problems, the present invention detects the pilot burst signal component added to the color signal output from the color signal reproducing circuit, and eliminates the pilot burst signal from the color signal based on this detection. An object of the present invention is to provide a video recording and reproducing device that eliminates erased portions and allows proper reproduced images without hue disturbance on a TV or the like.

Means for Solving the Problems In order to solve the above problems, the video recording and reproducing device of the present invention includes a horizontal synchronization separation circuit for extracting a horizontal synchronization signal from the output of a luminance signal reproduction circuit, and a color signal processing for the reproduction system. A color signal regeneration circuit, a gate circuit that passes the output of the color signal regeneration circuit only during the horizontal synchronization signal period and outputs a pilot burst signal added during the horizontal synchronization signal period, and detects the level of the pilot burst signal from the output of the gate circuit. The chrominance signal reproducing circuit is equipped with a detection circuit that performs the following, and an erasure circuit that erases the pilot burst signal in the chrominance signal reproduction circuit using the output of the detection circuit.

According to the above-described configuration, the pilot burst signal added to the chrominance signal is positioned during the horizontal sync signal period, so that the horizontal sync signal is extracted from the luminance signal, and the gate circuit extracts the horizontal sync signal from the chrominance signal. Only the signal period is allowed to pass, the pilot burst signal is taken out, and the level is detected. Based on this output signal, the actual pilot burst signal can be reliably deleted from the color signal. Therefore, malfunctions of PC circuits in TVs and the like can be eliminated, and proper reproduced images without hue disturbance can be obtained.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a video recording and reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a luminance signal reproducing circuit, 2 is a horizontal sync separation circuit that extracts a horizontal sync signal from the reproduced luminance signal, 3 is a color signal reproducing circuit that performs color signal processing in the reproduction system, and 4 is a period of the horizontal sync signal. 5 is a detection circuit that detects the level of the pilot burst signal; 6 is a gate circuit that allows the output from the chrominance signal reproduction circuit 3 to pass through and outputs a pilot burst signal; The erasing circuit 7 is a mixing circuit that mixes the reproduced luminance signal and the output of the erasing circuit 6.

The operation of the video recording and reproducing apparatus of this embodiment configured as described above will be described below with reference to FIGS. 1 and 2. FIG. 2 shows waveforms at points 9 from point a in FIG. 1. In FIG. 1, a luminance signal reproducing circuit 1 performs reproduction system luminance signal processing and outputs it (FIG. 2a). Next, the horizontal synchronization signal of the luminance signal a is taken out from the horizontal synchronization separation circuit 2 (FIG. 2b). After the color signal reproduction circuit 3 performs reproduction-related color signal processing, it is output (C in Figure 2), and the gate circuit 4 allows the color signal C to pass only during this period due to the horizontal synchronization signal. Extracts only the pilot burst signal located during the horizontal synchronization signal period (second
Figure d). Next, in the detection circuit 6, the pilot burst signal d
Detects the level of and outputs it as a pulse signal e (
Figure 2). The erasing circuit 6 removes the pilot burst signal from the color signal C output from the color signal reproduction circuit 3 based on the pulse signal e (FIG. 2f). Next, the mixing circuit 7 mixes the luminance signal a and the color signal f after erasing the pilot burst and outputs it as a video signal (Fig. 2, q).
).

As described above, according to this embodiment, the horizontal synchronization signal is extracted by the horizontal synchronization separation circuit 2, and the gate circuit 4 allows only the horizontal synchronization signal period to pass from the color signal output from the color signal reproduction circuit 3. This allows the pilot burst signal to be extracted.

Then, the detection circuit 5 detects the level of the pilot burst signal and outputs it as a pulse signal, and then the erasing circuit 6 erases the seven pilot burst signals based on the pulse signal, so that the actual pilot burst signal is The position of the image can be detected, and erasing can be performed reliably. Therefore, malfunctions of APC circuits in TVs and the like can be eliminated, and proper reproduced images without hue disturbance can be obtained.

Effects of the Invention As described above, according to the present invention, a pulse signal is generated from a horizontal synchronizing signal so as to sufficiently include the pilot burst signal period, the position of the actual pilot burst signal is detected, and the detected period is Because the configuration eliminates the pilot burst signal in the color signal, variations in the pilot burst signal insertion position, variations in the pulse signal position,
Despite variations in the time lag between the luminance signal and the chrominance signal, the pilot burst signal can be reliably erased. Therefore, it is possible to obtain excellent effects such as eliminating malfunctions of APC circuits in TVs and the like and obtaining proper reproduced images without hue disturbance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram of main parts of the video recording and reproducing apparatus, and FIG. 3 is a signal waveform showing the position of a pilot burst signal. 4 is a block diagram of a conventional video recording and reproducing device, FIG. 5 is a signal waveform diagram of main parts of the same video recording and reproducing device, and FIG. 6 is a pilot burst signal position or pulse in the same video recording and reproducing device. FIG. 7 is a signal waveform diagram of the main part when there is no change in the signal position, and FIG. 7 is a signal waveform diagram of the main part when there is a change in the pilot burst signal position or pulse signal position in the same video recording and reproducing apparatus. 2...Horizontal synchronization separation circuit, 3...Color signal regeneration circuit, 4...Gate circuit, 5...
・Detection circuit, 6...Elimination circuit. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1st
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Claims (1)

[Claims] a horizontal synchronization separation circuit that extracts a horizontal synchronization signal from the output of the luminance signal reproduction circuit; a color signal regeneration circuit that performs color signal processing in the reproduction system; a gate circuit for extracting a pilot burst signal added during the synchronization signal period; a detection circuit for detecting the level of the pilot burst signal from the output of the gate circuit; and a detection circuit for detecting the level of the pilot burst signal from the output of the detection circuit; A video recording and reproducing device comprising: an erasing circuit that erases a burst signal.