JPS61269206A - Wreck end searching device for video tape - Google Patents

Abstract

PURPOSE:To execute consecutive recording even after a video cassette is ejected once, by forming a signal for making a part in which a signal has been recorded and a part in which it is not recorded correspond to two states and showing them, and detecting its state variation time point. CONSTITUTION:In case an unused video tape 1a is used, the device goes to a rewinding reproducing mode, therefore, a cue head 11 starts a rewinding reproduction from a point b1, but since a cue signal is not recorded before reaching a point a1, a pulse signal S4 goes to a signal which rises at the point a1. By a rise of this pulse signal S4, a one shot multivibrator 15 is triggered and a pulse signal S5 which is maintained for a prescribed time t2 is sent out. As a result, by a fall of the pulse signal S5, a one shot multivibrator 16 is triggered and a stop signal S6 is sent out. In such a way, a video head 2 can be abutted on a position where the tape is rewound a little from the end of recording of the previous time.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to a videotape recend search device, and the present invention relates to a videotape recend search device, which allows the connection to be made even when a videocassette is once removed from a videotape recorder (hereinafter referred to as VTR) and then reloaded. It was devised so that it could be manipulated.

<Prior art> Images recorded on a cassette-type videotape (video cassette) cannot be edited with scissors and glue like images recorded on 8mm film, but they can be edited one after another using pose operations. It is possible to continue recording while However, with a simple pause operation, the next recording will start regardless of the track that has already been recorded, so
In this part, the tracks may become irregularly arranged, or the control signal may become discontinuous, causing the tracking servo to be off in this part during playback, resulting in a distorted image. To prevent this image distortion, it is necessary to make sure that the 0-0 signal is completely continuous on the video tape, or even if it is not continuous, the phase of the control signal does not change before and after switching. There is.

Various methods have been proposed to achieve this, but this method of recording so that there is no image disturbance or noise at the seams is called splicing. There is a method called a phase matching method as one method of this joint operation. In this system, when the pause button is operated, the capstan motor rotates in reverse with the pinch roller pressed, rewinding the videotape by a certain amount and waiting for the start of the next recording. If you cancel Bose mode in this state, the videotape will be driven, but it will first go into playback mode and will not immediately go into recording mode. During this time, the phase of the next recording signal's mount roll signal and playback control signal will match. Adjust the capstan drive as shown below, and then shift to recording mode.

<Means for Solving the Problems> Although the VTR according to the prior art has the above-described continuous shooting function, continuous shooting is no longer possible once the video cassette is removed from the VTR. This is because the video tape inside the video cassette moves during unloading when taking out the video cassette and loading when reloading the video cassette.

Taking this as an example of the U loading method, the fourth
This will be explained in more detail based on Figures 1) to 4(C). FIG. 4(&) shows the state during unloading, FIG. 4(C) shows the state during loading, and FIG. 4(b) shows the state in between. In FIGS. 4(a) to 4(c), 1 is a video cassette, 1a is a video tape, 1b is a supply reel, IC is a take-up reel, 2 is a video head, 3 is a cue head, 4 is a full width erase head, 5 is a guide pin,
6 is a U loading ring. These Figure 4(a)
~As shown in FIG. 4(C), for example, during loading, the take-up reel IC is fixed and the supply side IJ-/I
By freeing /ib and rotating the U loading ring 6 counterclockwise in the figure, the video chip 7'la is pulled out and wrapped around the video head 2 by the guide pin 5 that rotates together with this. On the other hand, during unloading, the supply reel 1b is fixed and the take-up reel IC is rotated to take up the winding. In this manner, for example, in one method, the video tape 1a is continuously fed to the winding side by loading and unloading. Therefore, as shown in FIG. 5, the relative position of the video tape 1a with respect to the drum center position of the video head 2 at the end of the previous recording is the point at which the video cassette 1 is ejected and then When it is loaded again and loading is finished, it will move from point a to point b. In addition, arrow C in the figure indicates videotape 1 at the time of recording.
This is the running direction of a.

In other loading methods, both the supply and take-up reels are free during loading, so the torque changes depending on the amount of videotape wound on both reels, and how the videotape moves. cannot be predicted, but the relative position of the video tape to the drum center of the video head at the end of the previous recording will move in the same way as in the case described above at the time of completion of loading prior to the next recording after ejecting the video cassette. Resulting in.

Thus, in the prior art, it is impossible to perform the splicing operation after the video cassette is -H ejected. An object of the present invention is to provide a videotape recend search loading method that enables splicing even when recording video tapes.

<Means to Solve the Problem> The present invention for achieving the above object is based on the following facts. Figure 6(a) shows the videotape 1a recorded on an unused videotape 1a. FIG. 6(b) is an explanatory diagram showing the state of the video tape 1& when it is recorded on the recorded video tape fla. As shown in FIG. 6(a), in the unused videotape 1a, nothing is recorded on the supply reel side (left side in the figure) from the recording end. In addition, as shown in FIG. 6(b), in the videotape 1a that has already been recorded, the newest recorded portion d1 blank (disappeared) portion e1 and oldest recorded portion molecules are formed in order from the take-up reel side to the supply reel side. ing. This is due to the mechanical positional relationship between the full width erase head 4 and the video head 2. That is, as is clear from FIGS. 4(a) to 4(C), the full-width erasing head 4 is located closer to the supply reel ib than the video head 2. Therefore, a blank portion e always occurs on the recorded video tape la.

For this reason, if a signal is formed that represents the two states of the part where the signal is recorded and the part where it is not recorded, the time when the previous recording ended (hereinafter referred to as this) can be detected by detecting the time when this state changes. (referred to as Wreck End)
From this point on, we can know the video
By rewinding la by a predetermined length, continuous shooting becomes possible.

The configuration of the present invention based on the above points includes a magnetic head for reproducing signals of a video tape that is run in the rewinding direction after completion of loading of the video tape, and a magnetic head for reproducing signals on the video tape based on output signals of this magnetic head. Circuit means for forming signals representing two states of a recorded portion and a non-recorded portion, and detection for detecting the end of recording in the previous recording based on a change in the state of an output signal of the circuit means. circuit means for sending out a stop signal for stopping rewinding of the videotape after a predetermined period of time has elapsed from the time of this detection; and two detecting means for respectively detecting the amount of videotape fed out from the take-up reel, a comparing means for comparing the amounts of videotape detected by both the detecting means and comparing the magnitude thereof, and a time point at which loading of the videotape is completed. If the result of the comparison by the comparison means is (amount of videotape fed out from the supply reel) > (amount of videotape fed out from the take-up reel), then the videotape being run in the rewinding direction a magnetic head for reproducing a signal; and circuit means for forming signals representing two states of a portion of a videotape where a signal is recorded and a portion where a signal is not recorded, respectively, based on the output signal of the magnetic head; Detection means for detecting the end of recording during the previous recording based on a change in the state of the output signal of this circuit means, and circuit means for sending out a stop signal for stopping rewinding of the videotape after a predetermined period of time has elapsed from this detection point. It is characterized by having the following.

<Example> Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. This embodiment is applied to the case where the video chip 761& is sent to the winding side by the above-mentioned loading method, that is, loading and unloading. That is,
com, if you eject the video cassette after recording and then reload it,
As shown in FIGS. 6(a) and 6(b), the relative position of the video tape 1a with respect to the drum center position of the video head 2 moves from point a to point b.

As shown in FIG. 1, an output signal from a magnetic head 11, which is a cue head in this embodiment, is supplied to a rectifier circuit 13 via an amplifier 12. The rectifier circuit 13 is a magnetic herad 11
It rectifies the output signal of and sends out pulse signals S4 corresponding to two states, a portion where a cue signal is recorded and a portion where it is not. The one-shot multivibrator 15 is triggered by the rise of the pulse signal S4 on the condition that the Nockles signal S3 supplied to one input terminal of the AND circuit 14 is at H level, and generates a Nockles signal S that lasts for a certain period of time t. , is sent. The one-shot multivibrator 16 is triggered by the falling edge of the pulse signal Ss and sends a stop signal S to put the VTR in a pause mode via the system control circuit 17 of the VTR main body (not shown).
Send 6. This system control circuit 17 is
When the video cassette 1 is loaded, loading is performed by supplying a loading signal S1 representing this. The one-shot multivibrator 18 is triggered by the rising edge of the loading completion signal S, which indicates the end of loading, and sends out a pulse signal S, which lasts for a certain period of time t1. However, the pulse signal S in this case is the Q output of the one-shot multivibrator 18, and is supplied to one input terminal of the AND circuit 14. The loading completion signal S is supplied to the system control circuit 17. At the falling edge of the system control circuit M17)! loading completion signal S, the VTR is put into rewind playback mode.

In this embodiment, when the video cassette 1 is loaded, a loading signal S as shown in FIG. 2(a) is supplied to the system control circuit 17, and as a result, the VTR starts loading. When the loading is completed, a loading completion signal St as shown in Fig. 2) is sent to the system A.
:2:/) is supplied to the roll circuit 17 and the one-shot multivibrator 18. At the rising edge of this p-ding completion signal S, the one-shot multivibrator 18
Q output S8 becomes L level, and this state remains for a certain period of time t.
1, and at the falling edge of the loading completion signal S2, the system control circuit 17 puts the VTR into the rewind playback mode. By entering the rewind play mode, the cue track 11 moves to the cue track ld (Fig. 6(a)
) and FIG. 6); the same applies hereafter). Now, the recording end of the cue track 1d in the previous recording is a %.
Then, the cue driver 11 starts rewinding and playing from point b1. Therefore, the waveform of the pulse signal S4, which is the output signal of the rectifier circuit 13, is as shown in FIG. 2(d) or FIG. 2(e).
). That is, FIG. 2(d) is similar to FIG. 6(a).
) When recording on an unused videotape la as shown in K, Fig. 2(e) shows the case when recording on an already recorded videotape fla as shown in Fig. 6(b). Compatible.

If you use an unused videotape 1a, the rewind playback mode will be activated as described above.
starts rewinding playback from point b1, but the cue signal is not recorded up to point a1, so the /4 pulse signal S4 is played back at point 87, as shown in Figure 2(d). It becomes a rising signal. The one-shot multivibrator 15 is triggered by the rise of this pulse signal S4, as shown in FIG. 2(f).
A pulse signal S, which lasts for a certain period of time t, as shown in FIG. As a result, the one-shot multivibrator 16 is triggered by the falling edge of the pulse signal S, and sends out a stop signal S6.

The system control circuit 17 receives a stop signal s.

Stops rewinding playback at the falling edge of . Thus, the video head 2 is rewinded slightly from the end of the previous recording.
can be brought into contact. After that, you can perform continuous shooting by performing the same operations as before. At this time, the predetermined time t is set to 1- in consideration of the amount of rewinding of the video chain fla necessary to perform continuous shooting.

If you use a recorded videotape 1&, it will go into rewind playback mode as described above.
As a result of starting rewind playback from the lotus point, the /4' pulse signal S4 rises at point b1 and was erased by the full-width erase head 4 during the previous recording, as shown in FIG. 2(e). The signal becomes a signal that once falls at one point, which is the end of the section, and then rises again at the 88th point. Since the pulse signal S is at the L level when the pulse signal S4 rises at the first point, the AND condition of the base pulse signals sm and S+ is not satisfied, and the output of the AND circuit 14 is at the L level. It will remain as it is. That is, the rising edge of the pulse signal S4 at A is ignored. Therefore, the subsequent operation is the same as in the case of the unrecorded videotape 1a, and in this case as well, the tape is rewound slightly from the end of the previous recording. The video head 2 can be brought into contact with the position. At this time, the predetermined time t1 is equal to b of the base pulse signal S4.
The setting is made so that the rise at one point is during the L level period of the pulse signal S3, and the rise at point b1 of the pulse signal S4 can be ignored.

In the first embodiment described above, the video tape 1a always moves to the winding side as the video tape 1a is ejected, but as in the case of adopting the M loading method, the video tape 1a moves to the supply side and FIG. 3 shows a block diagram of a second embodiment, which is an embodiment applied when it is not possible to predict which direction the winding side will move. As shown in the figure, in this embodiment, detectors 19 and 20, counters 21 and 22, a comparator 23, and switches 24 and 25 are added to the block shown in FIG. The detector 19 detects the feeding of the videotape 1a from the winding side to the supply side during loading, and the detector 20 detects the feeding of the videotape 1a from the supplying side to the winding side during loading. Counters 21 and 22 count the amount of feed of videotape 1a in each direction based on the output signals of detectors 19 and 20, and supply the results to comparator 23, respectively.

The comparator 23 compares the count values of the counters 21 and 22 and finds that (amount of videotape 1a fed out from the supply reel 1b)>(amount of videotape 1a fed out from the take-up reel 1c) Switch in case 24.25
Close. At this time, the counters 21 and 22 output the loading signal S.
1 and is reset at an appropriate time after completion of fourding. Therefore, when the relative positional relationship between the video tape 1a and the cue head 3 is the same as that shown in FIG. 6(a) or FIG. 6(b), the video tape 1a is Rewinding is performed.

On the other hand, if (t of the videotape la fed out from the supply reel 1b) < (amount of the videotape la fed out from the take-up reel IC), then the end portion of the previous recording section of the videotape 1a Since the camera is facing the video head 2, it is only necessary to start continuous shooting from this position. In the above description, a cue head is used as the head for detecting the record end, but the present invention is not limited to this, and it goes without saying that a video head or an audio head may be used.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, it is possible to perform continuous shooting even when the video cassette is once removed and then loaded again.

[Brief explanation of the drawing]

#! Figure 1 is a block diagram showing the first embodiment of the present invention, Figures 2 (a) to 2) are waveform diagrams showing the waveforms of each part, and Figure 3 is the second embodiment of the present invention. 4(a) to 4(c) are explanatory diagrams conceptually showing aspects of U loading, and FIGS. 5 and 6(a), (b).
) is an explanatory diagram for explaining the positional relationship between the video tape and the head. In the drawing, 1 is a video cassette, LA is a video tape, LB is a supply reel, LC is a take-up reel, 2 is a video head, 11 is a magnetic (cue) head, 13 is a rectifier circuit, and 14 is an AND circuit. , 15, 16.18 is one-shot multivibrator
, 1.9.20 is a detector, 21.22 is a counter, and 23 is a comparator.

Claims (2)

[Claims] (1) A magnetic head that plays back the signals of the videotape that is run in the rewinding direction after the loading of the videotape is completed, and based on the output signals of this magnetic head, it is possible to determine which parts of the videotape are recorded with signals and which parts are not. circuit means for forming signals respectively representing two states, a detection means for detecting the end of recording during the previous recording based on a change in the state of the output signal of the circuit means, and a detection means for detecting the end of recording in the previous recording, 1. A videotape recend search device comprising circuit means for transmitting a stop signal for later halting rewinding of a video arc. (2) two detection means that respectively detect the amount of videotape that is fed out from the supply side reel and take-up side reel of the video cassette when loading the videotape;
A comparing means compares the amounts of video tape detected by both detecting means and compares the magnitude thereof, and the result of comparison by the comparing means at the time of completion of loading of the video tape is (the amount of video tape fed out from the supply side reel). > (amount of videotape fed out from the take-up reel), a magnetic head plays back the signal of the videotape running in the rewinding direction, and a signal is recorded on the videotape based on the output signal of this magnetic head. circuit means for forming signals representing two states of a portion where the data is recorded and a portion where the portion is not; and a detection device that detects the end of recording during the previous recording based on a change in the state of the output signal of the circuit means. and,
1. A videotape recend search device comprising circuit means for sending out a stop signal for stopping rewinding of the videotape after a predetermined period of time has elapsed from the time of detection.