JPH05260433A - Transmission system for copy inhibit signal and copy inhibit system - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a copy prohibition method capable of performing copy prohibition control with a limited number of generations. A combination of a plurality of frequency signals having frequencies different from each other in a frequency interleaved manner with respect to a baseband signal of a video signal is used as a copy prohibition signal in a state where they do not exist at the same time. It is superimposed on the baseband signal and transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copy prohibition signal transmission system and a copy prohibition system in a VTR, for example.

[0002]

2. Description of the Related Art In order to substantially prevent duplication (so-called dubbing) of a recorded tape on which video software such as a movie is recorded, some kind of anti-duplication processing (hereinafter referred to as copy guard) is applied to the video signal. Has been.

In a consumer VTR, as one of the copy guard methods, as described in Japanese Patent Laid-Open No. 61-288582, a pair of a pseudo sync pulse and a positive pulse is provided in a vertical blanking interval. There is a method of inserting a plurality of the above and using an AGC circuit of a recording system having a predetermined characteristic as a copy guard corresponding process, which is often used. The copy guard signal is inserted in the vertical blanking interval because if the copy guard signal is directly inserted into the video signal portion, the contents of the video software may be damaged.

[0004]

However, in the case of the above method, since the copy guard signal is inserted in the vertical blanking interval, the copy can be easily performed by processing such as replacement of the synchronizing signal in the vertical blanking interval. The guard may be released.

Therefore, the applicant prohibits copying the spurious signal to the video signal in the effective screen section (copy protection).
The method of superimposing as a signal was previously proposed. That is,
In this method, for example, in a VTR in which a video signal is baseband-recorded with a luminance signal and component signals of red and blue color difference signals separated from each other, for example, a spurious signal having a frequency interleaved relationship with the luminance signal is duplicated. The prohibition signal is superimposed in the effective screen section. Then, the VTR on the recording side performs a process of inhibiting recording when the spurious signal is detected. In this case, since the copy prohibition signal has a frequency interleaved relationship with the luminance signal, spurious is not noticeable in the reproduced screen when reproduced.

By the way, recently, a generation limited copy method has been proposed in which the first generation from the original can be copied and the copy of the next generation is prohibited, and the copy prohibited method corresponds to this generation limited copy. It is desirable to be able to.

However, in the above-mentioned copy-prohibiting method proposed above, since the spurious signal to be superimposed on the luminance signal has a single frequency, it is difficult to realize so-called generation-limited copying.

In view of the above points, the present invention is a system that uses the spurious signal as a copy prohibition signal as described above, and is a copy prohibition system that can cope with generation-limited copying and a copy prohibition signal transmission system used therefor. The purpose is to provide.

[0009]

In order to solve the above-mentioned problems, the duplication prohibition system according to the present invention has a relationship of frequency interleaving with respect to a baseband signal of a video signal and a plurality of frequency signals having different frequencies. As a duplication inhibition signal, the duplication inhibition signals are superimposed on the baseband signal of the reproduced video signal and transmitted to the recording side in a state where they do not exist at the same time, and the recording side decodes the combination of the duplication inhibition signals, It is characterized in that recording permission or recording prohibition is determined according to the decoded output.

[0010]

The combination prohibition signal is formed by combining a plurality of types of frequency signals, and this signal is superimposed on the video signal and transmitted to the recording side. Therefore, the combination can be made to correspond to the code. Limitations can be specified.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a transmission method of a copy prohibition signal and a copy prohibition method according to the present invention will be described below with reference to a high-definition V
A case of applying to TR will be described with reference to the drawings.

Before describing the present invention, first, a high definition VTR will be described.

In a VTR that records and reproduces a high-definition (high-definition television) signal in a wide band and a high frequency band, in order to lower the frequency of the recording signal and narrow the frequency band,
A method of recording a signal for a unit time, for example, one frame by dividing it into a plurality of segments and a plurality of channels is used.

That is, the high-definition signal is a signal having 1125 horizontal scanning lines per 30 Hz in one frame, and the high-definition signal is a luminance signal Y, a blue color difference signal PB, and a blue color difference signal PB in the recording system of the VTR. It is input as a baseband signal including a component signal of the red color difference signal PR. Then, the input luminance signal and color difference signal are once A / D converted into digital signals and subjected to time-axis processing and color signal line sequential processing.

Then, it is divided into two channels, A and B, and a synchronization signal SYNC, a burst signal SB, etc., a color signal C, and a luminance signal Y are time-divided for each channel as shown in FIG. TDM (TIME D
IVISION MATRIX) signal is converted into a continuous recording signal of unit period H ^* . Then, this recording signal is returned to an analog signal, FM-modulated, and recorded on the magnetic tape by the rotary head.

Here, the unit period 1H ^* is set to have a time length which is almost twice as long as one horizontal period of the original high-definition signal by dividing the two channels, and a luminance signal and a color for one line are included in this 1H ^*. The signal is time-division multiplexed. The TDM waveform in FIG. 8 is a waveform after D / A conversion.

Then, the high-definition signal of each one frame is converted into the TDM signal as described above, and as shown in FIG. 9, A channel tracks TA and B channel tracks TB are alternately formed, for a total of 8 tracks. Is recorded on a magnetic tape as. In addition, A channel track T
One segment is composed of a pair of the A and B channel tracks TB, and the recording data for one frame is recorded as four segments SEG1, SEG2, SEG3, SEG4.

FIG. 10 shows an example of a rotary head device used in the recording / reproducing apparatus of this example. That is, the A-channel head 1A having the first azimuth angle and the B-channel head 1B having the second azimuth angle different from the first azimuth angle are arranged at the same rotation angle position of the rotary drum 3 at their rotation axes. It is attached by being offset by one track width in the direction. Similarly, the A channel head 2A having the first azimuth angle and the B channel head 2B having the second azimuth angle rotate the rotary drum 3 at a rotation angle position different by 180 ° from the heads 1A and 1B. It is attached by being offset by one track width in the axial direction.

The magnetic tape 4 is obliquely wound around the drum 3 over an angular range of 180 ° + α, and the rotary heads 1A, 1B, 2A and 2B are rotated at a rotational speed of 60 Hz. In the case of this example, the diameter of the drum 3 is, for example, 62 mm, the tape speed is 34.97 mm / s, and the track pitch is, for example, 15.11 mm.
It is said to be μm.

With the rotary head device having the above-mentioned structure, the rotary heads 1A and 1B and the rotary heads 2A and 2B are alternately arranged on the magnetic tape 4 at about 180 °.
In the tape contact section corresponding to the rotation angle, as shown in FIG. 9, eight oblique recording tracks are formed per frame and a high-definition signal is recorded.

That is, in one rotation, the rotary head 1A
And 1B contact the tape 4 in the first half of the 180 ° rotation section, the rotary heads 1A and 1B drive the A channel track TA1 and the B channel track TB1.
And the rotary heads 2A and 2B are in contact with the tape 4 in the latter half about 180 ° rotation section.
A channel tracks TA2 and B by A and 2B
The channel tracks TB2 are formed at the same time, and thereafter, this is alternately repeated.

In this case, two rotary heads 1A, 1B,
Alternatively, one segment is composed of two tracks which are simultaneously formed by the rotary heads 2A and 2B, and a video signal for a half field and an audio signal for a half field period related to this video signal are formed in the one segment. To P
The CM-converted signal is recorded in separate recording areas. Further, a copy prohibition code is recorded in a separate recording area. And 4 tracks TA1, TB
1 field for 1, TA2, TB2, 4 segment SE
A video signal and an audio signal of a high-definition signal for one frame are recorded by G1, SEG2, SEG3, and SEG4.

FIG. 7 shows a block diagram of an embodiment of the high definition VTR of this example. That is, as shown in FIG. 7, the luminance signal Y of the video signal input through the input terminal 11Y is A through the low pass filter 12Y.
The signal is supplied to the / D converter 13Y, A / D converted into a digital signal at the sampling frequency f _YCK = 44.55 MHz, and supplied to the TDM encoder 14.

Further, the input terminal 11B and the input terminal 11R
The blue color difference signal PB and the red color difference signal PR, which are respectively input through the above, are supplied to the A / D converters 13B and 13R through the low pass filters 12B and 12R, respectively, and are ¼ of the sampling frequency of the video signal. A / at sampling frequency f _CCK = 11.1375 MHz
The signals are D-converted, converted into digital signals, and supplied to the digital signal processing circuits 14.

In the digital signal processing circuit 14, the digital signal processing such as the time axis processing and the line-sequential processing of the color difference signals is performed by the clock having the clock frequency f _TCK = 30.753 MHz which is phase locked to the sampling clock of the luminance signal. And is encoded into the above-mentioned TDM signal. The circuit 14 also performs so-called shuffling processing for rearranging the TDM signal in a predetermined order from the original signal. Then, the output is divided into two channels A and B.

The data of the respective channels A and B from the digital signal processing circuit 14 are supplied to the adding circuits 15A and 15B, respectively, and a sync signal (different from the sync signal in the video signal) SYNC and a burst signal SB Etc. have been added.

The data of the two channels A and B is D
D / A supplied to the A / A converters 16A and 16B.
From these D / A converters 16A and 16B, the TDM including the synchronization signal SYNC, the burst signal SB, etc., the color signal C, the luminance signal Y, etc., as shown in FIG.
A waveform signal is obtained.

This signal is supplied to the low-pass filter 1 respectively.
An analog recording processing circuit 18A through 7A and 17B,
The signal is supplied to 18B, is subjected to pre-emphasis processing, and is FM-modulated. The FM-modulated A channel data is supplied to the A channel rotary heads 1A and 2A via the recording amplifier 19A, and F
The M-modulated B channel data is recorded by the recording amplifier 19
Is supplied to the rotary heads 1B and 2B via B, and as described above, 4 segments per frame, 8
Recorded as a track.

As described above, the audio signal is recorded on each track in a different recording area from the video signal described above. Further, for example, a 2-bit copy prohibition code is recorded in a recording area different from those of the video signal and the audio signal. This copy prohibition code is recorded in the index area on the tape or the reserve area in the video signal recording area. This copy prohibition code is usually inserted in a so-called original soft tape.

Next, the reproducing system will be described. That is, the reproduction signals from the A channel rotary heads 1A and 2A are supplied to the analog reproduction processing circuit 22A through the reproduction amplifier 21A, and the reproduction signals from the B channel rotary heads 11B and 2B are supplied to the reproduction amplifier 21B. Is supplied to the analog reproduction processing circuit 22B via. Then, in these analog reproduction processing circuits 22A and 22B, after FM demodulation, analog processing such as de-emphasis is performed.

The analog reproduction processing circuits 22A and 22
The output signal of B is supplied to the A / D converters 24A and 24B via the low-pass filters 23A and 23B, respectively, converted into digital signals, and then supplied to the digital signal processing circuit 25. The digital signal processing circuit 25 performs a de-shuffling process for returning the TDM signals rearranged at the time of recording to the original order, a decoding process for converting the TDM signals into luminance signals, and color difference signals of blue and red.

Further, in the digital signal processing circuit 25, the copy prohibition code from the index area in the recording track or the reserve area of the video signal is decoded, and the system controller (not shown) prohibits copying from the decoded output. It is determined whether or not copy protection is applied. And, as described below,
This system controller controls generation stop of the copy prohibition signal from the copy prohibition signal generation circuit.

The luminance signal from the digital signal processing circuit 25 is returned to the original analog signal through the D / A converter 26Y and the low pass filter 27Y and supplied to the output terminal 28Y.

The blue and red color difference signals from the digital signal processing circuit 25 are respectively supplied to the D / A converter 26.
The signal is returned to an analog signal by B and 26R and supplied to output terminals 28B and 28R through low pass filters 27B and 27R.

Next, FIG. 1 shows the entire system of the copy inhibition system according to the present invention. In FIG. 1, reference numeral 100 is a high-definition VTR on the reproducing side, and 200 is a high-definition VTR on the recording side. Hi-vision VTR10 on the playback side
When the video signal is reproduced by the reproduction system 101 of 0, the reproduced video signal, that is, the reproduction luminance signal Y and the reproduction color difference signals PB and PR are supplied to the superposition circuit 102. In the digital signal processing circuit 25 of the reproduction system 101,
The copy prohibition code reproduced from the recording track is decoded, and the decoded output is the system controller 10
3 is supplied. Then, the system controller 103
Then, the generation stop control signal of the copy prohibition signal is formed based on the decoded output, and the copy stop signal generation stop control signal is supplied to the copy prohibition signal generation circuit 104 as described above.

The copy prohibition signal generation circuit 104 forms the copy prohibition signal composed of the spurious signal as described above,
When the generation stop control signal from the system controller 103 indicates "generation", the duplication inhibition signal is supplied to the superposition circuit 102 to reproduce the reproduction luminance signal Y and the reproduction color difference signal P.
It is superimposed on all of B and PB, on one reproduction signal, or on two reproduction signals.
In the case of this example, there are n kinds (n ≧ 2) of copy prohibition signals in a frequency interleaved relationship with the superimposed video signal.
The spurious signals of n kinds of frequencies are superimposed in a predetermined repetition period so that they do not exist at the same time.

The frequencies to be interleaved are, for example, (N + 1/2) fH and (N + 1 / f) in the luminance signal band.
4) fH (where N is a positive integer and fH is the horizontal frequency of the video signal). When using spurious signals of n kinds of frequencies, the value of N is N1, N
2, ..., Nn. The recording band of a high-definition signal is set to 20 MHz at maximum, but a spurious signal having a frequency of 5 to 6 MHz is used as the duplication prohibiting signal to be superimposed. The frequency signal used may not be a sine wave signal.

In this case, as a combination of spurious signals of n kinds of frequencies, a method of extracting and combining spurious signals of arbitrary k kinds (k ≦ n) of frequencies from spurious signals of n kinds of frequencies, and n kinds of spurious signals are combined. There are a method of combining the presence or absence of each spurious signal of a frequency, a method of mixing the both methods, and the like. Here, in the method of combining the presence or absence of each of the spurious signals of n kinds of frequencies, considering the presence or absence of the spurious signals of each frequency as 1 bit, an n-bit code is transmitted at the n kinds of frequencies. equal. The example described below is a method of combining the presence or absence of each of these n types of spurious signals.

As a method of superimposing a combination of these spurious signals of n kinds of frequencies on a video signal, for example, one screen (one field) is divided into n, and spurious signals of each frequency are divided into small screens. A method of assigning and superimposing can be adopted. In this case, the duplication prohibition signal is
It is not necessary to allocate to all fields, and only one field may be superposed for every plural fields. Further, as another superimposing method, for example, for every m fields (m> n), a method of allocating one of n types of spurious signals to each one of n fields in this m field is used. Good.

As described above, using the spurious signals of n kinds of frequencies is equivalent to transmitting an n-bit copy prohibition code. Therefore, it is possible to set the generation limitation as the copy prohibition condition, and further, it is possible to set the copy generation limitation to an arbitrary generation according to the number of bits.

The copy prohibition condition set by superimposing the copy prohibition signal on the reproduced video signal is determined based on the copy prohibition code recorded in the index area on the tape or the reserve area of the video signal.

The video signal thus transmitted from the reproducing VTR 100 is supplied to the recording system 201 in the recording VTR 200. A part of the signal supplied to the recording system 201 is supplied to the copy inhibition signal detection circuit 202, the copy inhibition signal is extracted from the video signal, and the combination is decoded. The decoded output is supplied to the system controller 203. The system controller 203 receives this decoded output and determines whether to record or stop recording. The system controller 203 also uses, as described below in this case,
Since the generation for which copying is prohibited is determined from the decode output, when recording, according to the decode output,
The copy prohibition code to be recorded in the index area or the reserve area of the video signal is determined and recorded together with the recording video signal.

Next, the reproduction prohibition signal generation circuit 10 on the reproducing side.
4 and a specific example of the copy inhibition signal detection circuit 202 on the recording side will be described. In the example described below, a screen (1 field) is vertically divided into two vertically, and spurious signals of two types of frequencies are separated and superimposed on the upper half video signal and the lower half video signal of the screen. This is the case. As the spurious signals of two kinds of frequencies, a spurious signal F1 having a frequency f1 when the value of N is N1 and a spurious signal F2 having a frequency f2 when the value of N is N2 are used. And
The duplication prohibition signal may be superposed on each field, but in this example, it is assumed that one field is superposed on a plurality of fields, for example, five fields.

FIG. 2 is a reproduction inhibit signal generation circuit 1 on the reproducing side.
In the block diagram of an example of 04, 111 is a reproduction signal processing circuit. The horizontal synchronizing signal HD (FIG. 3A) from the reproduction signal processing circuit 111 is supplied to the frequency dividing circuit 112, and the frequency thereof is divided into 1/2. A signal having a frequency of 1/2 · fH from the frequency dividing circuit 112 is supplied to the phase comparing circuit 113. Further, the oscillation center frequency fo is fo = (N +
A variable frequency oscillator 114 of 1/2) fH is provided, and the output signal of the variable frequency oscillator 114 is the variable frequency divider circuit 1.
It is supplied to 15 and divided by 1 / (2N + 1)
The signal is / 2 · fH. And this frequency dividing circuit 11
5 is compared with the output signal of the frequency dividing circuit 112 in the phase comparison circuit 113, and the phase comparison error output is supplied to the variable frequency oscillator 114, and the variable frequency oscillator 11
The output signal 4 is controlled so as to be phase-synchronized with the horizontal synchronizing signal HD.

In this case, if the N value for determining the frequency division ratio of the variable frequency dividing circuit 115 is set to N1, the variable frequency oscillator 1
The frequency of the output signal of 14 is f1 = (N1 + 1/2) f
H, the spurious signal F1 is obtained, and N2 (≠ N
In the case of 1), the frequency of the output signal of the variable frequency oscillator 114 becomes f2 = (N2 + 1/2) fH, and the spurious signal F2 is obtained. That is, two types of spurious signals F1 and F2 that are frequency interleaved with the video signal are obtained.

In this case, the combination of these two types of spurious signals F1 and F2 can be made to correspond to a 2-bit code as shown in FIG. In FIG. 4, "0" means that the spurious signal F1 or F2 is not superimposed on the luminance signal, and "1" means that the spurious signal F1 or F2 is superimposed on the luminance signal. Then, as shown in FIG. 4, when the 2-bit code is "00", that is, when both signals F1 and F2 do not exist, it is possible to freely copy. 2-bit code is "01" or "1"
0 ", that is, spurious signals F1 and F2
When either of the two is superimposed on the luminance signal, the second
It indicates that only generations can be duplicated. And
When the 2-bit code is "11", it indicates that copying is prohibited.

The variable frequency dividing circuit 115 is composed of, for example, a preset counter, and the frequency dividing ratio is changed by setting a preset value of this counter. The preset value for the N value is supplied from the system controller 116. As mentioned above, the system controller 116
Is supplied with the decoding output SD of the copy prohibition code from the reproduction signal processing circuit 111, and a preset value U generated in the signal section in the upper half of the screen according to the decoding output SD.
P and a preset value DW generated in the signal section in the lower half of the screen are determined. The preset values UP and DW are supplied to one and the other input ends of the switch circuit 117.

When it is determined by the system controller 116 that the spurious signal F1 is superimposed on the video signal in the upper half of the screen and the spurious signal F2 is superimposed on the video signal in the lower half of the screen, the preset signal UP corresponds to N1. And the preset signal DW corresponds to N2. When it is determined to superimpose only the spurious signal F1, both the preset signals UP and DW are set to correspond to N1. When it is decided to superimpose only the spurious signal F2, the preset signal UP
Both DW and DW correspond to N2.

The system controller 116 also outputs a superposition control signal GT which determines whether or not the duplication inhibition signal is superposed on the video signal. As described above, when either or both of the spurious signal F1 and the spurious signal F2 are superimposed on the video signal, the system controller 116
Is determined, the superimposition control signal G1 is set to "1". When it is determined that both the spurious signals F1 and F2 are not superimposed on the video signal, the system controller 116 sets the superimposition control signal G1 to “0”,
As will be described later, the copy inhibition signal is prevented from being generated by the copy inhibition signal generation circuit 104. At this time, the preset signal from the system controller 116 may have any value.

The horizontal synchronizing signal HD from the reproduction signal processing circuit 111 is supplied to the counter 118 as a clock, and the vertical synchronizing signal VD (FIG. 5A) is supplied to the reset terminal of the counter 118, and the counter 118 is supplied. In, the number of horizontal lines from the beginning of one screen is counted. The count value output of the counter 118 is supplied to the decoder 119 and decoded. The decoder 119 generates a switching signal SW (FIG. 5B) that inverts the state when it detects the position of the vertical center of the screen from the decoded count value. The switching signal SW switches the switch circuit 117 to the preset signal UP side in the upper half period of the screen and to the preset signal DW side in the lower half period of the screen. Therefore, the output signal of the variable frequency oscillator 114 becomes a frequency signal according to the preset value UP in the upper half period of the screen and becomes a frequency signal according to the preset value DW in the lower half period.

As described above, the system controller 1
16 generates preset signals UP and DW determined according to the reproduced copy inhibition code, and these are switched by the switch circuit 117. Therefore, the output signal of the variable frequency oscillator 114 is as shown in the code correspondence table of FIG. Signal generation state.

The output signal of the variable frequency oscillator 114 is supplied to the gate circuit 120. Also, the reproduction signal processing circuit 1
The horizontal synchronizing signal HD from 11 is supplied to the horizontal blanking signal generation circuit 121, which generates the horizontal blanking signal HBLK (FIG. 3B). The horizontal blanking signal HBLK causes the gate circuit 120 to perform the horizontal blanking period. Is turned off. Therefore, the output signal of the gate circuit 120 is as shown in FIG. 3C, and the copy inhibit signal is not superimposed on the video signal during the horizontal blanking period. This is to prevent the superimposition of the duplication prohibition signal even in the horizontal blanking period, since it adversely affects the separation of the synchronization signal.

The output signal of the gate circuit 120 is for removing unnecessary high frequency components, and is passed through the low pass filter 122 for the spurious signal F1 of the frequency f1 and the low pass filter 123 for the spurious signal F2 of the frequency f2. It is supplied to one and the other input ends of the switch circuit 124. The switch circuit 124 is used in the decoder 11
A signal SW from 9 switches to one and the other input terminal in the upper half section and the lower half section of the screen in synchronization with the switch circuit 117.

The signal from the switch circuit 124 is supplied to the gate circuit. On the other hand, the reproduction signal processing circuit 111
The vertical synchronizing signal VD from is supplied to the counter 126,
Is counted. The count value of the counter 126 is decoded by the decoder 127. Then, the decoder 127 outputs a signal G2 (FIG. 5C) which becomes “1” for one field period every five fields in this example, from the count value of the counter 126.
2 is supplied to the AND gate 128.

The AND gate 128 is also supplied with the superposition control signal G1 from the system controller 116. Therefore, the AND gate 128 is for a period in which both the superposition control signal G1 and the signal G2 are "1", that is, when the duplication inhibition signal is superposed,
It becomes "1" only for the period of 1 field in 5 fields. The output of the AND gate 128 is the gate circuit 125.
The gate circuit 125 is supplied to the AND gate 1
It is opened only when the output of 28 is "1". And
In the case of this example, the gate circuit 125 is opened 1
During the field period, the duplication prohibition signal is generated by the superposition circuit 129.
It is supplied to Y, 129PB and 129PR and is superimposed on all of the luminance signal Y and the color difference signals PB and PR. Figure 5
The superimposed signal shown in D corresponds to the code "11", and the signal F1 is superimposed on the upper half section of the screen and F2 is superimposed on the lower half section. The signals Y, PB, and PR on which the copy inhibition signal is superimposed are output terminals 130Y and 130P.
B and 130PR, respectively, and supplied to the recording-side VTR.

FIG. 6 is a block diagram of an example of the copy prohibition signal detection circuit 202 of the recording side VTR, and this example shows only the case of detecting the copy prohibition signal in the luminance signal Y.
With respect to the color difference signals PB and PR, the duplication inhibition signal can be similarly detected by providing the same circuit.

In FIG. 6, the luminance signal Y input through the input terminal 211 is the delay circuit 212 for one horizontal section.
Is supplied to the comb filter 214 including the subtraction circuit 213. When the duplication inhibition signal is superimposed on the luminance signal Y, the duplication inhibition signal is extracted and obtained from the comb filter 214.

The output signal of the comb filter 214 is supplied to the detection circuit 216 via the bandpass filter 215 for the frequency f1 and level-detected. Then, the detected output is supplied to the level comparison circuit 217, which compares it with the threshold value th to detect the presence or absence of the spurious signal F1 of the frequency f1. The output signal of the comb filter 214 is also supplied to the detection circuit 219 via the bandpass filter 218 for the frequency f2 and level-detected. Then, the detected output is supplied to the level comparison circuit 220, which compares it with the threshold value th to detect the presence or absence of the spurious signal F2 of the frequency f2.

Decoder 22 outputs the presence / absence detection outputs of the spurious signals F1 and F2 of the comparison circuits 217 and 220.
1 is supplied. The outputs of the level comparison circuits 217 and 220 completely correspond to the codes shown in FIG. 4, so the decoder 221 performs the decoding as shown in FIG. Then, the decoder 221 supplies the decoded output to the system controller 222. System controller 2
Reference numeral 22 controls recording execution or recording stop according to the output of the decoder 221.

The system controller 222 also creates a copy prohibition code to be recorded in the index area or the reserve area of the video signal according to the output of the decoder 221 when recording is executed, and supplies this to the recording processing circuit 224. To do. That is, the content of the 2-bit code decoded by the copy prohibition signal is, for example, "1".
If it is 0 ”or“ 01 ”, indicating that only the second generation can be copied, next-generation copying is prohibited. Therefore,“ 11 ”is created as the copy prohibition code to be recorded, and it is recorded on the tape. Record above.

In this example, the recording signal from the input terminal 211 is supplied to the recording processing circuit 224 after the copy inhibition signal is removed by the comb filter 223.
However, since the duplication inhibition signal is frequency-interleaved with the video signal, it is rarely noticeable in the playback screen, and since it is often superimposed on the video signal at a low level, it is recorded as it is superimposed. Also during playback,
For example, it is removed by a noise removal circuit, and the reproduced signal is hardly affected.

In the above example, the screen is divided in the vertical direction and the spurious signals of a plurality of types of frequencies are assigned to the divided screens. However, the screen may be divided in the horizontal direction, and further, in the vertical direction. It may be divided in both horizontal directions. When the screen is divided and the copy prohibition signal is superimposed in this way, if the copy prohibition signal is removed with a comb filter in order to cancel the copy prohibition process and perform so-called piracy, the frequency signal is Piracy cannot be easily performed because the copy prohibition signal component that cannot be removed remains at the boundary of the screen divisions that switch.

It is also possible to allocate spurious signals of one frequency to one field and superimpose spurious signals of n different frequencies over n fields. In this case, for each M field (M ≧ n), n kinds of spurious signals are superposed on the n fields so that the combination of the n kinds of spurious signals corresponds to the intended copy inhibition code. do it.

In the above example, V of the high definition signal is
The present invention is applied to the TR, but the present invention is not limited to this, and is applicable to all cases of the duplication prohibition method in the apparatus for baseband recording the video signal.

[0065]

As described above, according to the present invention, a plurality of types of frequency signals having a frequency interleaving relationship with a video signal are combined to form a copy inhibition signal, and the copy inhibition signal is used as the video signal. Since the above-mentioned combination is transmitted, the combination can be encoded as a code corresponding to the code for copy inhibition, and the copy inhibition control for limiting the generation can be easily performed.

Further, the copy-prohibiting signal transmitted from the reproducing side is decoded, and an appropriate copy-prohibiting code for realizing the generation-limited copy is easily formed in the recording signal on the recording side according to the decoded output. Then, it becomes possible to record this on a recording tape, and it is possible to realize a suitable generation limited copy system.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the overall configuration of a system that implements a copy inhibition method according to the present invention.

FIG. 2 is a block diagram of an embodiment of a copy inhibition signal generation circuit provided on the reproduction side.

FIG. 3 is a timing chart for explaining the operation of the example of FIG.

FIG. 4 is a diagram for explaining a combination of copy prohibition signals and the contents of the copy prohibition control.

5 is a timing chart for explaining the operation of the example of FIG.

FIG. 6 is a block diagram of an embodiment of a copy inhibition signal detection circuit provided on the recording side.

FIG. 7 is a block diagram of a configuration example of a high-definition VTR as an example of a system to which the present invention is applied.

FIG. 8 is a diagram for explaining a recording signal of a high-definition VTR.

FIG. 9 is a diagram for explaining a recording track pattern on a tape in a high definition VTR.

FIG. 10 is a diagram showing an example of a rotary head device used in a high-definition VTR.

[Explanation of symbols]

 100 reproduction side VTR 101 reproduction system 102 spurious signal superposition circuit 104 copy prohibition signal generation circuit 200 recording side VTR 201 recording system 202 copy prohibition signal detection circuit

Claims (3)

[Claims] 1. A video signal in which a plurality of frequency signals having frequencies different from each other are combined in a relationship of frequency interleaving with respect to a baseband signal of a video signal, and the duplication prohibition signals do not exist at the same time. A transmission method of a copy prohibition signal that is transmitted by being superimposed on the baseband signal of the signal. 2. A reproduced video in a relation of frequency interleaving with respect to a baseband signal of a video signal, and combining a plurality of frequency signals having different frequencies, and serving as a copy inhibition signal in a state where they do not exist at the same time. The signal is superimposed on the baseband signal of the signal and transmitted to the recording side. On the recording side, the code signal is decoded from the combination of the copy prohibition signals, and recording permission or recording prohibition is determined according to the decoded output. Copy protection method. 3. The duplication prohibition signal encoded according to the decoding output of the code signal obtained from the combination of the duplication prohibition signals in the reproduction signal, when the recording side determines that the recording is permitted. A duplication prohibition method that records on a recording medium together with a signal.