CN1026531C

CN1026531C - Method and circuit for recording and reproducing analog signals and anti-copy of tape

Info

Publication number: CN1026531C
Application number: CN 93109242
Authority: CN
Inventors: 林正豹; 刘学达
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-08-09
Filing date: 1993-08-09
Publication date: 1994-11-09
Anticipated expiration: 2013-08-09
Also published as: CN1083961A

Abstract

The present invention relates to a method for recording analog signals on tapes and anti-copying of the recording signals. In the present invention, various pulse signals are added during the process of the synchronous blanking of lines and fields, particularly, partial information signals in front of the field synchronization are converted to fixed levels (black levels) to cause synchronous impulse levels to rise gradually, and the synchronous impulse levels combine with the automatic gain compensation of a disturbed video recorder to damage the synchronous clamping during the process of copying or piracy of video tapes, so that the illegal copying of program tapes can be prevented to protect the copyright of video tapes.

Description

Method and circuit for recording and reproducing analog signals and anti-copy of tape

The present invention relates to the record of simulating signal and the Method and circuits of playback, particularly record simulating signal and anti-technical matters of duplicating thereof on tape or disk.

Development along with the video recording cause; the raising of people's level of cultural life; the phonotape and videotape cause is also improving constantly and is developing; therefore; in the making and distribution of audiovisual tape, particularly video-tape; bootlegging and piracy to video-tape are also more and more serious, and this will have influence on the development of making, protection and the audio-video cause of video-tape, and brings adverse influence.

In present existing technology, all do not solve video-tape well anti-ly duplicate, the problem of anti-piracy aspect.

The present invention is exactly the patent of having applied in the past: further raising, improved on the basis of 88107670.8 " upsetting the magnetic tape enciphering method of video recorder automatic gain compensation function " makes it reach more satisfied effect.

The objective of the invention is to be to overcome the shortcoming and defect part of above-mentioned prior art, and the Method and circuits of a kind of analog signal record and playback is provided,, reach the purpose of video-tape copyright protection to prevent the bootlegging of video-tape.

The objective of the invention is to realize by following proposal: the present invention is the row at video signal, the field synchronization black-out intervals adds various pulse signals, do not influencing under TV signal clamp and the synchronous situation, destroy the automatic gain compensation function of video recorder, specifically, be exactly when making the video-tape program, with the vision signals of preceding 14 row of field sync signal or 20 row parts convert to fixed level (being called the secret note level) and periodically or four alternately allow preceding 6 or 7 horizontal synchronizing pulse level rise to the secret note level one by one, the row of each during the secret note level increases by one and approaches the wide dyke of black level 6-10 μ s and dash simultaneously.This method is for the not influence of reproduction quality of program band; yet it cooperates with the encryption method that upsets the video recorder automatic gain compensation; can destroy video-tape is duplicating or the clamp of synchronous head during pirate pirate recordings; video-tape is duplicated or pirate pirate recordings image quality variation afterwards; make the image after duplicating bob occur, rock; even phenomenon such as image rolling etc., lose commercial value fully, thereby reach the copyright protection of video-tape.

Further specify the present invention below in conjunction with accompanying drawing:

Fig. 1 is the waveform synoptic diagram of the A mode of prior art.

Fig. 2 is the waveform synoptic diagram of the B mode of prior art.

Fig. 3 is the waveform synoptic diagram of the C mode of prior art.

Fig. 4 is a waveform synoptic diagram of the present invention.

Fig. 5 is a circuit block diagram of the present invention.

Fig. 6 is a main oscillogram in the circuit of the present invention.

In Fig. 1 of A mode;

The A mode is to add black pulse and white pulse after the field sync signal between six to eight departures date continuously, and black pulse width is 3 to 4 μ s, and the white pulse width is that 3 to 7 μ s change continuously or discontinuously.The white pulse amplitude slowly changes a little more than white level or at black level and between a little more than white level, for reducing the influence of this signal to the televisor clamp, also increases by 4 to 6 horizontal synchronizing pulses after eight row in addition.

In Fig. 2 of B mode;

The B mode is that the adding width is 0.7 to 1 μ s before and after each circumstances in which people get things ready for a trip synchronizing signal, and amplitude is a little more than the pulse of half white level, and the colour synchronisation positions adding width of 24 row are 2.5 μ s before field synchronization, and amplitude is a little more than the pulse of white level.

In Fig. 3 of C mode,

The C mode is to add the black pulse of 0.6 to 0.8 μ s and the white pulse of 1.5 μ s after colour burst signal, and the white pulse amplitude is a little more than white level.

In Fig. 4, be that vision signals with preceding 14 or 20 row of field sync signal change that to be higher than synchronous top 0.64～0.9V(black level be 0.6V into) fixedly secret note level, and four or eight alternately allow

front

6 or 7 horizontal synchronizing pulse level secret note level that rises one by one (i.e. two kinds of field over-over modes).One of during the secret note level each row increase simultaneously approaches the wide dyke of black level 6～10 μ s and dashes.

The partial information signal of record is meant 14 row or 20 row before field sync signal, the whole signals except that synchronous, equilibrium, colour synchronisation.

Owing to do not change, therefore, the televisor of video recorder all not have to influence in the row of preceding four field signals, field synchronization.And in Hou Sichang, there are six or seven synchronous level of row to rise to the secret note level one by one, when common record and replay, so can not all isolate this six or seven horizontal synchronizing pulses because the time constant of the synchronizing separator circuit of video recorder and televisor is bigger, therefore inoperative to the synchronous clamp circuit of video recorder.Televisor there is not influence yet, but piracy, when illegally recording video-tape, owing to upset the automatic gain compensation of video recorder, make luminance signal decay to 6 to 8d β, the level difference of secret note level and synchronous head is greatly reduced, the synchronous level difference of these six or seven row also is decreased to 6 to 8d β simultaneously, therefore the synchronizing separator circuit of video recorder just can be isolated this six or seven synchronizing pulses, and carry out the synchronous head clamp, to the synchronous head level, it is mistaken as is field sync signal with secret note level drop-down (decline) (effect that dyke dashes is exactly to improve drop-down possibility).Like this, playback time not only, beating appears in picture, and drum servo also is damaged, picture is shaken, and some televisors also can not separate this field sync signal of four because of drop-down (decline) of secret note level, make it can't make image (picture) occur rolling synchronously.Therefore, through the tape of this method encryption, after recording, playback time is to watch again, thereby reaches the copyright protection to video-tape.

In the circuit block diagram of Fig. 5:

Composite video signal is from D end input, after the video amplifier 1 amplifies, deliver to delay circuit 2 through 600 nanoseconds of time-delays after, enter clamp circuit 3, in clamp circuit 3, carry out synchronously and twice clamp of blanking, fix the level of its blanking signal.Signal is delivered to commutation circuit 4, in commutation circuit 4 incision secret note level, the white pulse of A, C mode and black pulse, composite synchronizing signal.Input B mode pulse in adding circuit 5, the secret note dyke dashes, and at secret note level section start six or seven row sync levels is risen one by one periodically (four are alternately), and the last signal of addition amplifies and output through video amplifier circuit 6.

In circuit diagram, the effect of synchronizing separator circuit 7 is to separate synchronous, the field sync signal of trip (compound) from the composite video signal of input.And isolated signal is delivered to

circuit

13,15,16,8,9,10,11,12, clamp pulse generating circuit 8 respectively produce synchronously and deliver to clamp circuit 3 with the blanking clamp pulse, do synchronous and the use of blanking clamp for it.The output signal of the synchronous counting circuit 13 of row is delivered to secret note level generation circuit 14 and the B mode produces circuit 11, the reference position of the synchronous counting circuit 13 decision secret note level of row and the reference position of B mode pulse.The secret note level produces circuit 14 and produces the secret note level signal, delivers to commutation circuit 4, and field synchronization counting circuit 15 produces four alternating signals, and delivers to tiltedly synchronous and tooth pulse-generating circuit 12.Tiltedly synchronously with in the tooth pulse-generating circuit 12 forming the dyke that width of every row is 6 to 10 μ s in the synchronous and secret note of row that six or seven level rise gradually and dashing.And the signal that forms delivered to adding circuit 5, white pulse and black pulse (as shown in Figure 1) that A mode circuit 9 forms the A mode are delivered to impulse summation circuit 10 with signal, B mode circuit 11 forms the pulse (as shown in Figure 2) of B mode and signal is delivered to adding circuit 5, C mode circuit 16 forms the white pulse of C modes and black pulse (as shown in Figure 3) and signal is delivered to impulse summation circuit 10, impulse summation circuit 10 is with the white pulse addition in white pulse in the A mode and the C mode, again commutation circuit 4 is delivered in white pulse and the black pulse (comprising synchronizing pulse) after with addition of the black pulse in the black pulse C mode in the A mode and composite synchronizing pulse phase adduction, made commutation circuit 4 produce switching signals.

The oblique sample circuit that produces circuit synchronously is to utilize row synchronously slope (by six to seven row slopes of secret note position signalling generation) to be taken a sample, and forms four or eight six to seven line synchronizing signals that impulse level rises gradually (being called oblique synchronizing signal) that replace in secret note level previous section;

Dyke is pulse delay and formation circuit towards circuit; Utilize the row synchronizing relay and during the secret note level, form pulse.

A, B, C, mode and secret note level be strong, in, weak selection circuit 17, cipher mode and secret note level high and low carried out manual switchover, the confession user freely selects.

But video amplifier circuit 6 two-way outputting video signals can be selected wherein one tunnel output arbitrarily for use.

Fig. 6 represents oscillogram main in the circuit of the present invention, it wherein 1. is the white pulse signal in the A mode that produces of A mode circuit 9, pulse width changes between 3～7 microseconds, recurrent interval changes between 2.5～4 microseconds, being total up to 6～7 row, 2. is black pulse signal wherein, just in time opposite with white pulse, pulse width was 2.5～4 μ s seconds, was spaced apart 3～7 microseconds sum than 1. Duoing four.

3. be the pulse signal that B mode circuit produces, pulsewidth is 0.7～1 μ s, and pulse of each row, and reference position is row edge, back synchronously, is expert at perhaps synchronously that the back produces along 1 μ s after, and pulse width is that 2.5 microseconds only 24 are gone this pulse is arranged before field synchronization.

4., 5. be white pulse and the black pulse signal that C mode circuit produces, the white pulse width is 1.5 μ s, and black pulse width is that 0.6～0.8 μ s white pulse is expert at synchronous back along 3.6 μ s～4 μ s places, and black pulse is located along about 3 μ s after being expert at synchronously.

6. be 6 line synchronizing signals that level rises gradually that tiltedly synchronously produce with tooth pulse-generating circuit 12,14 row before the field synchronization, impulse level rises gradually, and pulse width is that 4.7 μ s and four have this pulse of four nothings.

In instructions, the present invention only enumerates a kind of embodiment, and the technician in this professional skill field is appreciated that and various changes can be made all is possible, but the present invention is not limited.The present invention determines its protection domain by claim.

Claims

1, a kind of method of analog signal record is characterized in that: on recording medium, the partial information conversion of signals that writes down is become fixed level (being called the secret note level);

The level of the part synchronizing signal of record is risen gradually, and each row increases a pulse signal during the secret note level.

2, according to the analog signal record method of claim 1, it is characterized in that: the media of record is tape or disk.

3, according to the analog signal record method of claim 1, it is characterized in that: be recorded in the fixed level that the recording information signal on the recording medium converts to and be meant the fixed level that is higher than synchronous top.

4, according to the analog signal record method of claim 1, it is characterized in that: said recording section information signal was meant before field sync signal, the whole signals except that synchronous, equilibrium, colour synchronisation.

5, according to the analog signal record method of claim 1, it is characterized in that: be two kinds of field over-over modes, allow several horizontal synchronizing pulse level of fixed level front little by little rise to the secret note level, each one of row increase during the secret note level simultaneously approaches picture black, the pulse that width is determined.

6, a kind of device of analog signal record, deliver to delay circuit by the composite video signal of video input through video amplifier amplifying signal and be connected to clamp circuit, signal behind the clamp is delivered to commutation circuit, and the signal after the switching is after the adding circuit addition, by video amplifier outputting video signal:

The signal of input video is through synchronizing separator circuit, isolated composite sync and field synchronization, composite sync and field sync signal are delivered to the synchronous counting circuit of row, the field synchronization counting circuit, the clamp pulse generating circuit, A, B, C mode circuit, tiltedly synchronous tooth pulse-generating circuit, it is characterized in that: the output secret note position signalling of the synchronous counting circuit of row is sent into commutation circuit after the secret note level circuit forms the secret note level, A, the pulse signal of C mode circuit output is delivered to commutation circuit through the pulse adder circuit, the synchronous count signal of row is delivered to adding circuit after tiltedly producing circuit synchronously.

7, according to the pen recorder of claim 6, it is characterized in that: the pulse signal that A, C mode circuit produce is black and white pulse signal.

8, according to the pen recorder of claim 6, it is characterized in that: strong by A, B, C mode and secret note level, in, weak selection circuit, control the selection of A, B, C mode and the height of secret note level.

9, according to the pen recorder of claim 6, it is characterized in that: the sample circuit that tiltedly synchronously produces circuit is to utilize row to be taken a sample in the slope synchronously, forms the line synchronizing signal (being called oblique synchronizing signal) that a plurality of impulse levels of two kinds of field over-over modes rise gradually in secret note level previous section;

Dyke is pulse delay and formation circuit towards circuit; Utilize the row synchronizing relay and during the secret note level, form dyke and dash.