JP3401403B2 - Video signal processing circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device which is surely sensitive to a macrovision type copy guard signal in a recording system but not sensitive to a reproducing system.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 3 is a block diagram of a conventional VTR signal processing circuit. Figure 4 is a waveform of the AGC pulse signals Macrovision scheme, FIG. 5 is a waveform of the Macrovision color stripe signal. FIG. 6 is a screen view of a 21-line interval 4-line version of Macrovision color stripe, and FIG. 7 is a screen view of a 17-line interval 2-line version.

First, a conventional video tape radar (VT
The signal processing system of R) will be described. As shown in FIG. 3, the video signal is input to the AGC circuit 11. AGC circuit 1
In 1, the detection result of the AGC detection circuit 16 is fed back and the brightness level is controlled. The output of the AGC circuit 11 is input to the Y / C separation circuit 12. Although there are various configurations of the Y / C separation circuit 12, in the figure, a low-pass filter (Y.LPF) 13 for separating a luminance signal and a high-pass / band-pass filter (CH for separating a chroma signal) are used.
(PF / BPF) 14 is shown.

The output of the Y / C separation circuit 12 is input to the clamp circuit 15 for AGC detection and synchronous separation.
The output is input to the AGC detection circuit 16 and the sync separation circuit 18. The AGC detection circuit 16 outputs to the luminance recording system, and the sync separation circuit 18 outputs a composite sync signal. The output of the sync separation circuit 18 is input to a burst gate pulse generation circuit 19 to generate a burst gate pulse and is input to the recording APC circuit 20, and is also supplied to another chroma processing circuit.

The detection of the macrovision type copy guard signal and the operation of the copy guard in the VTR having the above circuit configuration will be described. FIG. 4 is a waveform of an AGC pulse signal for macrovision type copy guard. In the AGC pulse signal, a large pulse having a signal level of 117 IRE and a pulse width of 3.0 μsec is provided after the horizontal synchronization signal with a period of 8.9 μsec following the pseudo synchronization pulse having a signal level of 40 IRE. The scanning lines inserted are 12 to 19 lines of odd fields and 275 to 282 lines of even fields.

This AGC pulse signal is the AGC detection circuit 1
When detected at 6, the keyed AGC operates and a detection current flows, and the AGC circuit 11 converts the level. If the detection current exceeds the predetermined value here, the Macrovision scheme AG
It is determined that the signal is a C pulse signal, and the detection current is further increased to compress the recording level of the video signal to 40% or less. If the VTR is recorded in this state, the sync signal is also compressed and recorded at the same time, so that the sync separation cannot be performed at the time of the reproduction, the reproduction screen flows, and the burst gate pulse cannot be generated and the color is changed. No longer used, so VTR
You can restrict the copy by.

Next, the macrovision type color stripe signal will be described. As shown in FIG. 5, the phase of the color burst signal is opposite to the normal phase for the first half of the signal. The color burst signal of the opposite phase is the Advanced Split Burst.
(Hereinafter referred to as “ASB”), and is used as a copy guard of the color signal section. Both the normal phase and the anti-phase are composed of about 5.5 cycles.

There are two types of the method. As shown in FIG. 6, four lines of ASB are arranged in 21 line cycle, and as shown in FIG. 7, two lines of ASB are arranged in 17 line cycle. Is. The line containing ASB has 11 stripes on the screen because the color disappears.
It is called a color stripe because it consists of 13 pieces.

In the operation of the VTR, C. HPF / BPF14
Then, the chroma signal is separated, and signal processing for recording is performed. The ASB is extracted from the signal including the ASB by the burst gate pulse generated by the burst gate pulse generation circuit 19, and the phase is compared by the recording APC circuit 20.
Half of the phases of the extracted ASB are opposite phases,
Since the data cannot be drawn in by the recording APC circuit 20 and is recorded, the line having ASB is not colored during reproduction, and a striped screen is formed so that copying by the VTR cannot be performed.

[0010]

However, when this color stripe signal is used, in the conventional VTR recording system, most of the normal phase portion is gated due to variations in the timing of the burst gate pulse and the pulse width. There was something that happened. For this reason, the recording is performed without affecting the recording system so much, and at the time of reproduction, color is added as in the case without the copy guard, and the copy cannot be restricted in some cases. Further, when a signal having this copy guard is input to a reproduction system such as a monitor, it may react with an opposite phase portion and may not show a correct hue. Therefore, in the conventional device, the copy protection by the color stripe signal is not reliable.

According to the present invention, a color stripe signal, which is a copy control signal of the macrovision system, is surely sensitive in the recording system to prevent copy, and is not sensitive in the reproducing system to display an image normally. It is an object to provide a video signal processing circuit.

[0012]

SUMMARY OF THE INVENTION The present invention is Macrovision scheme AGC pulse signals and the color stripe signal Macrovision scheme that part of the state of color at the time of reproduction in reverse phase does not attach the phase of the color burst signal In a video signal processing circuit for performing copy protection in response to a copy guard signal consisting of, an AGC pulse detection circuit for detecting the presence or absence of the AGC pulse signal, and a color having no reverse phase unless the AGC pulse signal is detected. A normal burst gate pulse for extracting a burst signal, and a burst gate pulse generating circuit for generating a burst gate pulse for extracting an opposite phase portion of the color stripe signal when the AGC pulse signal is detected, A feature is that a burst gate pulse is output to the recording system.

According to the present invention, an AGC pulse detection circuit for detecting the presence or absence of the AGC pulse signal, and a normal burst gate pulse for extracting a color burst signal having no opposite phase if the AGC pulse signal is not detected, A burst gate pulse generation circuit for generating a burst gate pulse for extracting a normal phase portion of the color stripe signal when the AGC pulse signal is detected, and outputting the burst gate pulse to a reproducing system. To do.

[0014] With the configuration according to the present invention, when detecting an AGC pulse signal Macrovision method from the input video signal, it recognizes that copying inhibition state, for extracting antiphase portion of the color burst signal , The recording system is surely sensitive to the copy guard signal.

According to a configuration described in the present invention, when detecting an AGC pulse signal Macrovision method from the input video signal, it recognizes that copying inhibition state, for extracting normal phase of the color burst signal The reproduction system such as the monitor device is not sensitive to the copy guard signal.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments shown in FIGS.
Will be described with reference to. FIG. 1 is a block diagram of a circuit according to an embodiment of the present invention, and FIG. 2 is a timing diagram of generation of a burst gate pulse according to the embodiment.

First, a copy guard signal sensitive system for a macrovision type curler burst in a VTR will be described with reference to an embodiment of the present invention.

As shown in FIG. 1, the video signal is an AGC circuit 1
Entered in. In the AGC circuit 1, the detection result of the AGC detection circuit 6 is fed back to control the brightness level. The output of the AGC circuit 1 is input to the Y / C separation circuit 2. Although there are various configurations of the Y / C separation circuit 2, a low-pass filter (Y.LPF) 3 for separating the luminance signal and a high-pass / band-pass filter (C.HPF / BPF) for separating the chroma signal are shown in FIG. 4 is shown.

The output of the Y / C separation circuit 2 is input to the clamp circuit 5 for synchronous separation from AGC detection, and the front ends of the synchronization signals before detection are aligned. The output of the clamp circuit 5 is input to the AGC detection circuit 6 and the sync separation circuit 8,
The AGC detection circuit 6 outputs the luminance recording system and the AGC pulse detection circuit 7. When the video signal AGC pulse signal is superimposed Macrovision scheme is input to the AGC detection circuit 6 works is keyed AGC, the current flowing at this time A
The comparator of the GC pulse detection circuit 7 determines the presence / absence of the AGC pulse signal.

When the copy guard signal is detected by the AGC pulse detection circuit 7, the burst gate pulse generation circuit 9 is instructed to change the pulse operation. This is because the AGC pulse signal of the macrovision method is not always added to the video signal, so it is equipped with a reset circuit and when the sync signal is interrupted, such as when the signal is switched, or during recording, the recording mode is changed. This is because the operation is ended by resetting by switching to the stop mode.

The video signal that has passed through the clamp circuit 5 is taken out by the sync separation circuit 8, and the composite sync signal output is a servo system control system and other circuits (both not shown).
Is supplied to. Further, this synchronizing signal is input to the burst gate pulse generation circuit 9 to generate a burst gate pulse.

FIG. 2 shows the generation timing of the burst gate pulse of the macrovision method . The same figure (a) is the color burst signal, the gate pulse when there is no copy guard is shown in the same figure (b). On the contrary,
When the AGC pulse is detected by the AGC pulse detection circuit 7, a burst gate pulse is generated in which a burst gate pulse for extracting the front portion (reverse phase portion) of the color burst signal is entered as shown in FIG. It is generated in the circuit 9 and supplied to the chroma signal processing unit.

On the other hand, the chroma signal separated by the Y / C separation circuit 2 enters the recording APC circuit 10. Since the phase of the color burst signal extracted by the burst gate pulse generated by the burst gate pulse generation circuit 9 is the opposite phase, it is recorded by the recording APC circuit 10 without being pulled in.
Therefore, at the time of reproduction, the portion is not colored and the copy guard is activated.

Next, a description will be given of a copy guard signal sensitive system for a macrovision type curler burst in a monitor according to an embodiment of the present invention.

When displayed on a monitor, if a video signal reproduced by a VTR or a signal broadcast on air has a copy guard signal which causes a color stripe, it is not sensitive to the copy guard signal and is normally displayed. Must be displayed. Therefore, it is necessary to use a burst gate pulse for extracting the color burst signal whose generation timing is different from that of the VTR.

The burst gate pulse at this time is AG
When there is an AGC pulse in the C pulse detection circuit 7, the copy guard mode is entered, and as shown in FIG. 2D, the burst gate pulse generation circuit 9 is arranged to extract the portion (normal phase portion) after the color burst signal. Is generated by.
The chroma signal separated by the Y / C separation circuit 2 is recorded by APC.
The burst gate pulse generation circuit 9 is input to the circuit 10.
The phase comparison is performed with the color burst signal extracted by the burst gate pulse created in. Since the phase of the extracted color burst signal is a normal phase, the chroma signal is normally processed. In this way, even a video signal having a macrovision type copy guard can be normally displayed on the monitor.

Next, the timing of the burst gate pulse generation will be described. As shown in FIG. 2A, since the burst signal is superimposed on the back porch T for 8 to 10 cycles (11 cycles in ASB), the burst gate pulse is horizontally synchronized as shown in FIG. 2B. The signal is delayed by the time of the horizontal sync chip width t from the falling edge of the signal, and is generated with substantially the same width as the pulse width of the back porch T.

FIG. 2 (c) shows a burst gate pulse corresponding to the copy guard sensitive mode of the VTR. Since the opposite phase is extracted, the rising edge rises at the same timing as usual, and is 1 / 2T which is half the period of the back porch T. It is a pulse that falls with the pulse width of. The timing of this fall should actually be shorter than the pulse width of 1 / 2T in consideration of the deviation. With this pulse, the color burst of only the antiphase part is extracted.

On the other hand, FIG. 2D shows a burst gate pulse corresponding to the copy guard insensitive mode of the monitor. The rising edge is 1 / th of the period of the back porch T from the normal timing so as not to extract the antiphase portion. It is a pulse that rises with a delay of 2T and then falls with a pulse width of 1 / 2T. In consideration of the deviation and the like, it is preferable that the rising timing be later than 1 / 2T. With this pulse, the color burst only in the normal phase portion is extracted. A burst gate pulse generating circuit can be generally used by a known technique.

[0030]

As described in detail above, according to the present invention, an A- type image of the macrovision system is obtained from the input video signal.
When the GC pulse signal is detected, it is recognized that the copy is prohibited and the opposite phase portion of the color burst signal is extracted. Therefore, the video recording device is surely sensitive to the copy guard signal and can perform normal video recording. Can not. Also, AG
If there is no C pulse signal, the color burst signal is extracted as usual, so that normal signal processing without a copy guard signal is possible.

According to the present invention, if the input video signal has been detected AGC pulse signals Macrovision scheme recognizes that copy inhibited state, for extracting normal phase of the color burst signal, the monitor device Can display a normal image without being sensitive to the copy prohibition signal. Further, if there is no AGC pulse signal, the color burst signal is extracted as usual, so that normal signal processing without a copy guard signal is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a timing of generating a burst gate pulse according to the embodiment of the present invention.

FIG. 3 is a block diagram of a conventional VTR signal processing circuit.

4 is a waveform diagram of the AGC pulse signals Macrovision scheme.

FIG. 5 is a waveform diagram of a macrovision color stripe signal.

FIG. 6 is a screen view of a 4-line version with 21-line intervals of Macrovision color stripes.

FIG. 7 is a screen view of a two-line version of a macrovision color stripe with 17-line intervals.

[Explanation of symbols]

1 AGC circuit 2 Y / C separation circuit 3 LPF for brightness 4 HPF / BPF for chroma 5 Clamp circuit 6 AGC detection circuit 7 AGC pulse detection circuit 8 Sync separation circuit 9 Burst gate pulse generator 10 Recording APC circuit 11 AGC circuit 12 Y / C separation circuit 13 Luminance LPF 14 Chroma HPF / BPF 15 Clamp circuit 16 AGC detection circuit 18 Sync separation circuit 19 Burst gate pulse generator 20 Recording APC circuit

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 9/79 H04N 9/455

Claims (2)

(57) [Claims] And AGC pulse signals according to claim 1] Macrovision system, sensitive to a part of Macrovision scheme copy guard signal consisting of the color stripe signal to state that lacks color and during playback in reverse phase the phase of the color burst signal In a video signal processing circuit for copy protection, an AGC pulse detection circuit for detecting the presence or absence of the AGC pulse signal, and a normal burst gate for extracting a color burst signal having no antiphase if the AGC pulse signal is not detected A burst gate pulse generating circuit for generating a pulse and generating a burst gate pulse for extracting an opposite phase portion of the color stripe signal when the AGC pulse signal is detected, and outputting the burst gate pulse to a recording system. A video signal processing circuit characterized by: And AGC pulse signals wherein Macrovision system, sensitive to a part of Macrovision scheme copy guard signal consisting of the color stripe signal to state that lacks color and during playback in reverse phase the phase of the color burst signal In a video signal processing circuit for copy protection, an AGC pulse detection circuit for detecting the presence or absence of the AGC pulse signal, and a normal burst gate for extracting a color burst signal having no antiphase if the AGC pulse signal is not detected A burst gate pulse generating circuit for generating a pulse and generating a burst gate pulse for extracting a normal phase portion of the color stripe signal when the AGC pulse signal is detected, and outputting the burst gate pulse to a reproducing system. A video signal processing circuit characterized by: