JPH07114002B2 - Video tape rack end search device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a video tape REC end search device, and a video tape recorder (hereinafter referred to as a VTR) is used to take out a video cassette once and then re-load it to take a continuous shot. It was devised so that

<Prior Art> Images recorded on a cassette-type video tape (video cassette) cannot be edited with scissors and adhesive as when recorded on an 8 mm film, but they can be edited one after another using a pause operation. It is possible to record while recording. However, since the next recording will start regardless of the already recorded track with a simple pause operation,
At this part, the track arrangement becomes irregular, and the control signal becomes discontinuous, so that the tracking servo is lost at this part during reproduction and the image is disturbed. In order to prevent this image distortion, it is necessary that the control 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 the switching. Various methods have been proposed to realize this, but such a method of recording without any image distortion or noise at the joint is called joint photographing. As one of the methods of this joint photographing, there is a method called the "Faze matching method". In this method, when the pause button is operated, the capstan motor is rotated in the reverse direction while the pinch roller is pressed, and the video tape is rewound by a certain amount and the next recording is started. If the pause mode is released in this state, the video tape will be driven, but the playback mode will be entered first and the recording state will not start immediately. During this time, the phase of the control signal of the next recording signal and the phase of the playback control signal will match. The drive adjustment of the capstan is performed, and then the recording mode is entered.

<Means for Solving Problems> Although the VTR according to the related art has the above-described joint photographing function, once the video cassette is taken out from the VTR, joint photographing cannot be performed. This is because the video tape in the video cassette moves due to the unloading when the video cassette is taken out and the loading when the video cassette is reloaded.

Taking this as an example of the U loading method,
A more detailed description will be given with reference to FIGS.
FIG. 4 (a) shows an unloaded state, FIG. 4 (c) shows a loading state, and FIG. 4 (b) shows an intermediate state between the two. In addition, in FIGS. 4 (a) to 4 (c), 1
Is a video cassette, 1a is a video tape, 1b is a supply reel, 1c is a take-up reel, 2 is a video head, 3 is a cues head, 4 is a full-width erasing head, 5 is a guide pin, and 6 is a U loading ring. . As shown in FIGS. 4 (a) to 4 (c), for example, during loading, the winding reel 1c is fixed and the supply reel 1b is freed so that the U loading ring 6 is rotated counterclockwise in the drawings. The video tape 1a is pulled out and wound around the video head 2 by the guide pin 5 which is rotated integrally with the guide pin 5 when the video tape 1a is rotated. On the other hand, during unloading, the supply-side reel 1b is fixed and the winding-side reel 1c is rotated to wind the reel. In this way, for example, in one method, the video tape 1a is gradually sent to the winding side by loading and unloading. Therefore, as shown in FIG. 5, when 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 passes through unloading and loading, that is, the video cassette 1 is once ejected, At the time when loading is completed and loading is completed, the vehicle moves from point a to point b. The arrow C in the figure indicates the running direction of the video tape 1a during recording.

As another loading method, both the supply side and take-up side reels are free during loading, so the torque changes depending on the amount of video tape wound on both reels and how the video tape moves. However, the relative position of the video tape with respect to the center position of the drum of the video head at the end of the previous recording moves as before at the completion of loading before the next recording after the ejecting of the video cassette. Will end up.

Thus, in the conventional technique, it is impossible to perform joint shooting after the video cassette is once ejected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object thereof is to provide a tape end search mounting of a video tape which enables the continuous shooting after the video cassette is once ejected.

<Means for Solving Problems> The present invention that achieves the above object is based on the following facts. FIG. 6 (a) is an explanatory diagram showing the state of the video tape 1a when recorded on the unused video tape 1a, and FIG. 6 (b) shows the video tape 1a when recorded on the recorded video tape 1a. It is explanatory drawing which shows a state. As shown in FIG. 6 (a), in the unused video tape 1a, nothing is recorded on the supply reel side (left side in the figure) from the end of recording. Further, as shown in FIG. 6 (b), in the recorded video tape 1a, the newest recording part d, the blank (erasing) part e, and the old recording part f are arranged in this order from the take-up reel side to the supply reel side. Has been formed. This is due to the mechanical positional relationship between the full-width erase head 4 and the video head 2. That is, as apparent from FIGS. 4 (a) to 4 (c), the full-width erasing head 4 is located closer to the supply reel 1b than the video head 2. Therefore, the recorded videotape 1a must have a blank area e.
Occur. For this reason, if a signal representing a portion where a signal is recorded and a portion where a signal is not recorded are made to correspond to two states, respectively, and signals are formed respectively, the time when the state changes is detected and the time when the previous recording is completed (hereinafter Is referred to as the "record end"), and therefore, if the video tape 1a is rewound by a predetermined amount from this point, the joint shot becomes possible.

The configuration of the present invention based on the above points is such that a magnetic head for reproducing a signal of the video tape which is run in the rewinding direction after the loading of the video tape is completed, and a signal in the video tape based on the output signal of the magnetic head. Circuit means for forming signals representing the recorded portion and the non-recorded portion respectively corresponding to two states, and detection for detecting the recording end at the time of the previous recording by the state change of the output signal of this circuit means. Means and circuit means for sending a stop signal for stopping the rewinding of the video tape after a lapse of a predetermined time from the detection time point, and a reel for supplying the video cassette at the time of loading the video tape. And two detecting means for respectively detecting the amount of the video tape fed out from the take-up reel, and both detecting means. The result of comparison between the comparison means for comparing the detected video tape amounts and the size of the detected video tape and the comparison means at the time when the loading of the video tape is completed is (amount of the video tape fed from the supply side reel)> (winding In the case of the amount of video tape unwound from the side reel), the magnetic head that reproduces the signal of the video tape running in the rewinding direction, and the portion where the signal is recorded on the video tape based on the output signal of this magnetic head. Circuit means for forming signals representing the two states corresponding to the two states and the other portions, a detecting means for detecting the recording end at the time of the previous recording by the state change of the output signal of this circuit means, and this detecting means. Circuit means for sending a stop signal for stopping the rewinding of the video tape after a predetermined time has elapsed from the time point.

<Examples> Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the first embodiment of the present invention. The present embodiment is applied to the case where the video tape 1a is sent to the winding side by the above-mentioned loading method, that is, loading and unloading. That is, in this case, after recording, the video cassette 1 is ejected,
Then, when reloading and loading are performed, as shown in FIGS. 6 (a) and 6 (b), the relative position of the video tape 1a to the drum center position of the video head 2 is from point a. Move to point b.

As shown in FIG. 1, the output signal of the magnetic head 11, which is a queue head in this embodiment, is rectified by an rectifier circuit via an amplifier 12.
Supplied to 13. The rectifier circuit 13 rectifies the output signal of the magnetic head 11 and sends out a pulse signal S ₄ corresponding to two states, that is, a portion where the queue signal is recorded and a portion where the queue signal is not recorded. The one-shot multivibrator 15 is triggered by the rising edge of the pulse signal S ₄ provided that the pulse signal S ₃ supplied to one input terminal of the AND circuit 14 is at the H level, and the pulse signal S lasts for a certain time t ₂ Send ₅ . One-shot multivibrator 16 has pulse signal S ₅
A stop signal S ₆ is sent via the system control circuit 17 of the VTR main body (not shown) to set the VTR to the suspend mode. When the video cassette 1 is loaded, the system control circuit 17 causes the loading by the loading signal S ₁ representing the loading to perform loading.
The one-shot multivibrator 18 sends out a pulse signal S ₃ which is triggered by the rising of the loading completion signal S ₂ which indicates the end of loading and which lasts for a certain time t ₁ . However, the pulse signal S ₃ in this case serves as the output of the one-shot multivibrator 18, and is supplied to one input terminal of the AND circuit 14. The loading completion signal S ₂
Is supplied to the system control circuit 17. The system control circuit 17 rewinds the VTR to the reproduction mode at the trailing edge of the loading completion signal S ₂ .

In this embodiment, when the video cassette 1 is loaded, the loading signal S ₁ as shown in FIG. 2 (a) is supplied to the system control circuit 17, and as a result, the VTR starts loading. When loading is complete, Fig. 2 (b)
A loading completion signal S ₂ as shown in (1) is supplied to the system control circuit 17 and the one-shot multivibrator 18. At the rising of the loading completion signal S ₂ , the output S ₃ of the one-shot multivibrator 18 becomes L level, and this state is maintained for a certain time t ₁ , and at the falling of the loading completion signal S ₂ , the system control circuit 17 outputs VTR. Enter rewind playback mode. By entering the rewind reproduction mode, the queue head 11 is moved to the queue track 1d (see FIGS. 6 (a) and 6 (b); the same applies hereinafter).
Play the queuing signal recorded in. Now, assuming that the recording end of the previous track 1d is a ₁ , and the relative position of the video tape 1a to the key head 11 at the completion of loading accompanying reloading of the video cassette 1 is b ₁ , the key head 11 is a point. b Rewind playback starts from ₁ . Therefore, the waveform of the pulse signal S ₄ which is the output signal of the rectifying circuit 13 is shown in FIG. 2 (d) or 2 (e).
As shown in. That is, FIG. 2 (d) is shown in FIG. 6 (a).
When recorded on an unused video tape 1a as shown in Fig. 2, Fig. 2 (e) corresponds to the recorded video tape 1a as shown in Fig. 6 (b). ing.

When the unused video tape 1a is used, the rewind playback mode is set as described above, so that the queue head 11 b ₁
Rewind reproduction is started from the point, but the queue signal is not recorded up to the point a _1, so the pulse signal S ₄ rises at the point a _{1 as} shown in FIG. 2 (d). Becomes The rising of the pulse signal S ₄ triggers the one-shot multivibrator 15 for a certain period of time as shown in FIG. 2 (f).
A pulse signal S ₅ that lasts t ₂ is transmitted. As a result, the one-shot multivibrator 16 is triggered by the trailing edge of the pulse signal S ₅ , and the stop signal S ₆ is sent out. The system control circuit 17 stops the rewinding reproduction at the falling edge of the stop signal S ₆ . Thus, the video head 2 can be brought into contact with the position slightly rewound from the end of the previous recording. After that, if the same operation as the conventional one is performed, the joint photographing can be performed. At this time, the fixed time t ₂ is set in consideration of the amount of rewinding of the video tape 1a necessary for performing the continuous shooting.

When the recorded video tape 1a is used, the rewind playback mode is set as described above, and the queue head 11 b ₁
As a result of starting the rewinding reproduction from the point, the pulse signal S ₄ is
As shown in FIG. 2 (e), and once again standing rise signal at the falling a ₁ point at point g is the end of the erased portion by full-width erasing head 4 when the rising last recorded in b ₁ point Become. When the pulse signal S ₄ rises at point b ₁ , the pulse signal
Since S ₃ is at the L level, the AND condition of the pulse signals S ₃ and S ₄ is not satisfied, and the output of the AND circuit 14 remains at the L level. That is, the rising edge of the pulse signal S ₄ at point b ₁ is ignored. Therefore, the subsequent operation is unrecorded video tape.
Similar to the case of 1a, also in this case, the video head 2 can be brought into contact with the position slightly rewound from the end of the previous recording. At this time, the fixed time t ₁ is the pulse signal
The rising edge of S _{4 at} the b ₁ point is in the L level period of the pulse signal S ₃ , and the rising edge of the pulse signal S _{4 at} the b ₁ point is set in consideration.

In the above-mentioned first embodiment, the video tape 1a is always moved to the winding side due to the ejecting of the video cassette 1. However, as in the case of adopting the M loading system, the video tape 1a is supplied to the winding side and the winding side. FIG. 3 shows a block diagram of a second embodiment, which is an embodiment applied when it cannot be predicted which one of the two sides will move. As shown in the figure, in this embodiment, the blocks shown in FIG.
22, a comparator 23, and switches 24 and 25 are added. The detector 19 is a video tape for loading.
The detector 20 detects the unwinding of 1a from the winding side to the feeding side, and detects the unwinding of the video tape 1a from the feeding side to the winding side during loading. The counters 21 and 22 count the feeding amount of the video tape 1a in each direction according to the output signals of the detectors 19 and 20, and the results are respectively compared by a comparator.
Supply to 23. The comparator 23 compares the count values of the counters 21 and 22 and is (amount of the video tape 1a fed from the supply reel 1b)> (amount of the video tape 1a fed from the take-up reel 1c). If necessary, the switches 24 and 25 are closed. At this time, the counters 21 and 22 are set by the loading signal S ₁ and reset at an appropriate time after the loading is completed. Therefore, videotape 1a and Queue Head 3
When the relative positional relationship of (1) is similar to that shown in FIG. 6 (a) or 6 (b), the video tape 1a is rewound by the same operation as in the first embodiment. on the other hand,
If (amount of video tape 1a delivered from supply reel 1b) <(amount of video tape 1a delivered from take-up reel 1c), the end portion of the previous recording portion of video tape 1a is video Since it is opposed to the head 2, it is sufficient to start the joint shooting from this position. In the above description, the queue head is used as the head for detecting the ledge, 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 described in detail with reference to the above embodiments, according to the present invention, it is possible to take a continuous shot when the video cassette is once taken out and then reloaded.

[Brief description of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, and FIG.
2 (a) to 2 (g) are waveform diagrams showing the waveforms of the respective parts, FIG. 3 is a block diagram showing the second embodiment of the present invention,
4 (a) to 4 (c) are explanatory views conceptually showing the aspect of U loading, FIG. 5 and FIGS. 6 (a) and (b).
FIG. 4 is an explanatory diagram for explaining the positional relationship between the video tape and the head. In the drawings, 1 is a video cassette, 1a is a video tape, 1b is a supply side reel, 1c is a take-up side reel, 2 is a video head, 11 is a magnetic (queue) head, 13 is a rectifier circuit, 14 is an AND circuit,
Reference numerals 15, 16 and 18 are one-shot multivibrators, 19 and 20 are detectors, 21 and 22 are counters, and 23 is a comparator.

Claims (2)

[Claims] 1. A magnetic head for reproducing a signal of the video tape which is run in the rewinding direction after the loading of the video tape is completed, and a portion where the signal is recorded on the video tape based on the output signal of the magnetic head and the other portion. Circuit means for forming signals respectively representing the part and the two states, and detecting means for detecting the recording end at the time of the previous recording by the state change of the output signal of the circuit means,
And a circuit means for sending a stop signal for sending a stop signal for stopping the rewinding of the video tape after a lapse of a predetermined time from the detection time point. 2. A comparison between two detection means for detecting the amount of each video tape fed from the supply reel and the take-up reel of the video cassette during the loading of the video tape, and the amount of the video tape detected by both detection means. The result of comparison between the comparison means for comparing the size and the comparison means at the time when the loading of the video tape is completed is (the amount of the video tape fed from the supply side reel)> (the video fed from the winding side reel). In the case of the amount of tape), the magnetic head for reproducing the signal of the video tape traveling in the rewinding direction, and the portion where the signal is recorded and the portion where the signal is not recorded on the video tape based on the output signal of this magnetic head are two Circuit means for forming respective signals corresponding to the two states, and a change in the state of the output signal of this circuit means A video tape rack characterized by having a detection means for detecting the end of recording at the time of recording and a circuit means for transmitting a stop signal for stopping the rewinding of the video tape after a lapse of a predetermined time from the detection time point. End search device.