JPH0524574B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a continuous automatic playback device for a plurality of video tape recorders, which switches the plurality of video tape recorders alternately or sequentially and automatically and continuously plays back only the necessary recorded portions on a common receiver. In particular, a non-recording section of a videotape is used to detect whether or not the tape section being played is a non-recording section in order to stop, rewind, cue the tape, and give playback commands to other video tape recorders. Regarding the detection method.

Conventional continuous automatic playback devices for multiple video tape recorders that switch between multiple video tape recorders alternately or sequentially to automatically and continuously reproduce only the necessary recorded portions on a common receiver are capable of automatically and continuously reproducing only the necessary recorded portions on a common receiver. A special cue signal is recorded at the end, and this cue signal is detected during playback and recorded by a video tape recorder (hereinafter referred to as VTR).
to stop and rewind the other VCR.
The method is to give regeneration commands to the This method requires two or more audio tracks, and cannot be applied to VTRs with monaural audio. Additionally, special processing was required to record cue signals on tape. Furthermore, with this method, it was not possible to cue the recording section after rewinding.

The present invention was proposed in view of the above problems, and it does not require special processing such as recording cue signals, can be used for VTRs that record monaural audio, and can also be used to cue the recording section. The purpose of the present invention is to provide a recording unit detection method.

Recorded video tapes include those that are recorded immediately from the beginning of the tape, those that appear a few minutes after playback begins, and those that lose the video signal and synchronization signal immediately after the recorded portion ends, or Even after the recording part ends, there is no change in the level of the single video signal, that is, the brightness signal.
For example, there are various types of video signals, such as those that record video signals of images without pictures, such as a white screen or a blue screen.

The present invention reliably detects whether the tape being played back is a recording section or a non-recording section, regardless of the various recording states of the recorded tape, and stops or stops the VTR.
It is used to rewind, cue, and issue playback commands to other VCRs. That is, the present invention detects whether there is a change in the level of the brightness signal or the presence of a synchronization signal in the reproduced video signal output from the VTR, detects that there is no synchronization signal, and then detects that the state continues for a predetermined period of time. The device determines that the playback of the recorded portion of the tape has ended when the recording section of the tape is present, and detects a change in the level of those brightness signals or the appearance of a synchronization signal, stops playback, and searches the beginning of the tape. It is.

The present invention will be described below with reference to drawings of embodiments. FIG. 1 is a block diagram of a continuous automatic playback device for a plurality of video tape recorders to which a method for detecting non-recorded portions of video tapes is applied, according to an embodiment of the present invention. 1 is a continuous automatic playback device for multiple video tape recorders, 2 is VTR A, 3 is VTR B, 4
5 is a television receiver that is connected to VTR A or VTR B and plays the recorded tape, and 5 is output from the video output terminal T _VO and audio output terminal T _SO of the continuous automatic playback device 1 of a plurality of video tape recorders, respectively. This is an amplifier that modulates and amplifies the video and audio signals of VTR A or VTR B. The video signal of VTR A output from the video signal output terminal T _VA is output from the video signal input terminal T _V1 , and the audio signal of VTR A output from the audio signal output terminal T _SA is output from the audio signal input terminal T _S1 . The data is input to the continuous automatic playback device 1 of the video tape recorder. VTR output from video signal output terminal T _VB
The video signal of VTR B is output from the video signal input terminal T _V2 and the audio signal output terminal _TSB . The audio signal of VTR B is output from the audio signal input terminal T _S2 to the continuous automatic playback device 1 of each video tape recorder. input. 10 connects the video signal output terminal _TVO and the audio signal output terminal _TSO0 to the video signal input terminal _TV1 ,
Audio signal input terminal T _S1 side or video signal input terminal
T _V2 , VTR switched to the audio signal input terminal T _S2 side
This is an output selector switch. 30 is a VTR output switching circuit that switches the VTR output switching switch 10 when the non-recorded section detection circuits 15 and 25 detect that playback of the recorded section has finished. T _c1 and T _c2 are remote control signal output terminals to VTR A and VTR B, respectively. T _cA and T _cB are respectively
This is the remote control signal input terminal for VTR A and VTR B. 12, 13, and 14 are the remote control signal output terminals _{Tc1 and} VTR A respectively.
A stop command signal output circuit that outputs a stop command signal to put the device in stop mode, a rewind command signal output circuit that outputs a rewind command signal to put it in rewind mode, and a play command signal output circuit to output a play command signal to put it in play mode. It is a circuit. 22, 23, and 24 are connected to the remote control signal output terminal T _c2 of the VTR.
A stop command signal output circuit that outputs a stop command signal to put B in stop mode, a rewind command signal output circuit that outputs a rewind command signal to put B in rewind mode, and a play command signal to output a play command signal to put B in play mode. This is an output circuit. Reference numeral 20 denotes a 24-hour timer for automatically reproducing the plural video tape recorder continuous automatic reproducing apparatus 1. When the set time is reached, a reproduction start signal is output to the reproduction command signal output circuit 14, and reproduction starts from VTR A. When the rewind command signal is output from the rewind command signal output circuits 13 and 23 and VTR A or VTR B starts rewinding, time starts, and when the set time is reached, the rewind command signal output circuits 17 and 27 respectively output the rewind command signal. 14,2
This is a timer that outputs a signal to 4 to start playback, that is, to locate the beginning of the tape. 15, 25
are non-recording section detection circuits which determine whether the tape section being played back in VTR A and VTR B is a recording section or a non-recording section, and outputs a "high" signal if it is a non-recording section. Details of the non-recording portion detection circuits 15 and 25 will be described later. 16 and 26 are respectively
When the non-recording section detection circuits 15 and 25 detect that the VTRs A and VTR B have entered the recording section during the beginning of the tape, that is, that they are at the beginning of the recording section, the stop command signal output circuits 12 and 22 are activated, respectively. outputs a signal to VTR A or VTR to stop playback.
This is a gate circuit that puts B into a standby state. 18,2
8 is a stop command signal output circuit 12, when the non-recording section detection circuits 15, 25 detect that the recording sections of VTR A and VTR B have finished playing back, respectively.
22 and reproduction command signal output circuits 14, 24,
This is a gate circuit that outputs a signal to the VTR output switching circuit 30 to stop the VTR being played, and also switches the VTR output switching switch 10 to put the other VTR into the playing state.

Next, as shown in FIG. 2, for example, tapes T _A and T _B recording programs P _A and P _B are respectively
Set the case where VTR A and VTR B alternately perform continuous automatic playback on the television receiver 4, and
The operation of the continuous automatic playback device 1 for a plurality of video tape recorders shown in the figure will be explained with reference to the timing chart in FIG. 3. First, both tapes T _A and T _B are set to the beginning position. Then, when the set time _tp for starting reproduction arrives, a signal for starting reproduction is output from the 24-hour timer 20 to the reproduction command signal output circuit 14. This causes a playback command signal to be output to the VTR.
A starts playing and displays the program on television receiver 4.
P _A is played. At time _t2 , when a predetermined period of time has elapsed after the end of this playback, the non-recording portion detection circuit 15
It is detected that the non-recorded part of T _A is being played back, that is, the playback of program P _A has ended, and the stop command signal output circuit 12, VTR output switching circuit 30, and playback command signal output circuit 24 are set to "high". The program P _B is output on the television receiver 4 by outputting a signal, stopping the VTR A, and switching the VTR output changeover switch 30 to start playing back the VTR B. On the other hand, at approximately the same time that the stop command signal is output from the stop command signal output circuit 12, a signal is also output to the rewind command signal output circuit 13 to output a rewind command signal, and the tape T _A of VTR A is output. rewinding starts and ends at time _t3 . Then, at time t4, when the set time set by the timer ₁₇ (this set time is determined to be a little long considering the maximum length of the tape) has elapsed from the rewinding end time _t3 , the playback command signal output circuit 14 A signal is output to VTR A, a reproduction command signal is output, and VTR A starts cueing. Timer 17 after starting this cue
Since a "high" signal is output from the gate circuit 16 to the gate circuit 16, the output of the gate circuit 16 becomes "high" at time _t5 when the non-recording portion detection circuit 15 detects the "beginning" of the program P _A , and the program stops. The command signal output circuit 12 outputs a stop command signal and the VTR A stops. That is, VTR A completes cueing and enters a standby state. Then, at time _t6 , the reproduction of the program _PB recorded on the tape _TB is completed. Thereafter, at time _t7 , when a predetermined period of time has elapsed, the non-recorded portion detection circuit 25 detects that the non-recorded portion of the tape T _B is being played back, that is, that the playback of the program P _B has ended, and sends a stop command signal. output circuit 22, VTR output switching circuit 30,
A "high" signal is output to the reproduction command signal output circuit 14. After that, perform the same operation as described above, and
A is played and program P _A is displayed on the television receiver 4.
At the same time, tape T _B of VTR B is rewound, cueing is completed, and VTR B enters the standby state. In this way, VTR → VTR B → VTR A
→..., VTR A and VTR B alternately enter playback mode, and the program P _A → program is displayed on the television receiver 4.
P _B →program P _A . . . P _A and P _B are alternately and continuously played.

Next, the non-recording portion detection circuits 15 and 25 will be explained. Figure 4 shows this tape non-recording section detection circuit 1.
5.25 is a block diagram. 100 is the playback video signal input from the video signal input terminal _TV1 or _TV2
This is a low-pass filter that removes color signal components from _S1 . 101 is a synchronization signal separation circuit that extracts only a synchronization signal from the reproduced video signal _S2 from which color signal components have been removed. A clamp circuit 102 shifts the signal level of the reproduced video signal _S2 from which the color signal component has been removed to a DC level. Reference numeral 103 denotes a synchronization signal part sampling circuit which extracts the synchronization signal part of the signal _S3 from which only the synchronization signal is extracted as one pulse signal. 1
Reference numeral 04 denotes a sync signal portion filling circuit that eliminates changes in the DC level of the sync signal portion by matching the signal level of the sync signal portion of the output signal S ₄ of the clamp circuit 102 to the luminance signal level. FIG. 5 is a circuit diagram showing one example of a specific circuit of this synchronization signal filling circuit 104, and FIG. 6 is a waveform diagram showing the operation of this circuit. Switch SW is synchronization signal extraction circuit 1
When the potential of the output signal _S5 is zero, the intercept is on the terminal _T3 side, and when the potential of the output signal _S5 becomes positive, it switches to the terminal _T4 side. Therefore,
When the output signal _S5 of the synchronization signal extraction circuit 103 is at zero potential, the voltage of the luminance signal portion of the output signal _S4 of the clamp circuit 102 is charged to the capacitor C, and the output signal
When _S5 becomes a positive potential, that is, the synchronization signal part, the switch is activated.
The intercept of SW switches to terminal T ₄ , the potential of the synchronizing signal part of the output signal S ₄ is filled with the charging potential of the capacitor C, and the output signal S ₆ is almost smooth except for the part where the level of the luminance signal changes. It becomes a converted DC signal. Reference numeral 105 denotes a video change detection circuit that extracts only the alternating current component, which is the change in the video signal, from the output signal S ₆ of the synchronization signal portion filling circuit 104 . That is, the output signal _S7 becomes a signal that emphasizes the change regardless of the brightness level. 106 connects the output signal S ₇ of the image change detection circuit 105 to the voltage V _CC resistor R ₂ ,
This is a comparator that shapes the waveform by comparing it with the reference voltage divided by _R3 . 107 is a comparator 106
This is a noise removal circuit that removes small noise components such as dropout noise that remain in the output signal _S8 . 108 is an image change no detection circuit composed of a retriggerable monostable multivibrator that uses, for example, the pulse of the signal S ₉ from which noise components have been removed as a trigger pulse, and the pulse width of the output signal S ₁₀ is set to 10 (seconds). When set, if there is no change in the video signal for more than 10 seconds, there will be no pulse in the signal _S9 during that time, so
The output signal _S10 falls to "low".

109 is the output signal S ₃ of the synchronization signal separation circuit 101
This is a synchronization signal non-detection circuit that changes the output signal S ₁₁ from "high" to "low" when it detects that there is no synchronization signal in the output signal S ₃ for 2 (seconds), for example, when no video signal is detected. Like the circuit 108, it is constructed of, for example, a retriggerable monostable multivibrator.

110 is a NOR circuit, which is a video change non-detection circuit 10
8 output signal S ₁₀ or synchronous signal non-detection circuit 109
When the output signal S ₁₁ is “low”, that is, when the program ends and there is no video change or synchronization signal, the output signal S ₁₂ becomes “high” and the above-mentioned
The VTR is stopped, played, and the VTR output is switched.

FIG. 7 is a waveform diagram of signals at various parts of the non-recording portion detection circuit of FIG. 4. In the figure, it is assumed that the program ends at time _t11 , and thereafter the screen has a single brightness, with noise mixed in at two points along the way. The VTR video signal _S1 up to the end of the program, that is, time _t11 , has a change in the level of the brightness signal, and a color signal is superimposed on this brightness signal. There is no change in the level of the brightness signal in the VTR video signal _S1 after the program ends, and of course there is no color signal superimposed thereon. Before these VTR video signals S ₁ pass through the video change detection circuit 105 , only the level change portion of the luminance signal and noise components are extracted, waveform-shaped by the comparator 106 , and then sent to the noise removal circuit 107 .
Only the pulse signal corresponding to the level change portion of the luminance signal remains in the signal _S10 from which the noise component has been removed.
This pulse signal causes the image change no detection circuit 108
The monostable multiviprator is triggered and the signal _S10 becomes “high”, but from the final pulse
It falls to “low” at time t ₁₂ , after 10 seconds. As a result, the output signal _S12 of the NOR circuit 110 is inverted and becomes "high", and this "high" signal _S12 is sent to the terminal.
The signal is outputted from _T6 to each circuit shown in FIG. 1, and the above-described operation is performed.

FIG. 8 is a waveform diagram of each signal when the VTR reproduced video signal contains only continuous noise without the video signal itself. In this case, these noises are not removed by the noise removal circuit 107, and the output signal _S9 is made up of a series of individual noises and becomes one pulse signal, which is the same as the image change detection signal. By the way, since this noise signal does not have a synchronization signal, in this case, the above-mentioned synchronization signal non-detection circuit 109
When, for example, two seconds have elapsed since the synchronization signal disappeared, the output signal _S11 is set to "low" to detect that the playback of the recording section has ended.

The present invention determines whether the part of the tape being played back is a recording section or a non-recording section by checking the level change of the brightness signal of the reproduced video signal output from the VTR or the presence or absence of a synchronization signal. It is possible to easily and reliably detect the end of playback in the recording section without performing any special processing such as recording a cue signal, and it is also possible to locate the beginning of the tape. Therefore, the continuous automatic playback device for multiple video tape recorders according to the present invention is capable of extremely efficient continuous automatic playback of VCRs regardless of the various recording states of the tapes, and is capable of continuously automatic playback of VTRs with high efficiency even when the audio is recorded in monaural. It can also be used for VTR.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a continuous automatic playback device for a plurality of video tape recorders, which performs continuous automatic playback of two VTRs alternately by using a method for detecting unrecorded portions of video tapes according to an embodiment of the present invention, and FIG. is the first
3 is a timing chart showing the operation of the continuous automatic playback device of the multiple video tape recorders shown in FIG. 1, and FIG. 4 is a non-recording section shown in FIG. 1. Detection circuit 1
A circuit diagram showing one embodiment of No. 5, 25, FIG.
6 is a waveform diagram of input and output signals of the sync signal section filling circuit 104, and FIGS. 7 and 8 are non-recording section detection circuits 15 and 2.
5 is a waveform diagram of signals at each part of FIG. 15, 25...Non-recording section detection circuit.

Claims (1)

[Claims] 1. When a video tape recorder is playing back, it is detected that the playback of the recording section has ended, the playback of the video tape recorder is stopped, and rewinding is performed, and after a predetermined period of time has elapsed from the start of rewinding. When playback is started and it is detected that the playback of the non-recording portion has ended, playback is stopped and the video tape recorder is placed in a standby state, and the video tape recorder that is in the standby state and scheduled to be played next In a continuous automatic playback device for multiple video tape recorders, which switches the multiple video tape recorders alternately or sequentially and plays back only the necessary recorded portions on a common receiver by putting the video tape recorders in playback mode. The non-recorded portion of the tape is being played back by detecting that at least one of the level change of the brightness signal based on the playback video signal of the tape recorder and the synchronization signal based on the playback video signal continues for a predetermined period of time. A method for detecting a non-recorded portion of a videotape, the method comprising detecting a non-recorded portion of a videotape.