JPH0834021B2 - VTR splicing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a joint photographing system of a VTR (magnetic recording device).

[Outline of Invention]

In a VTR in which a video signal is recorded on a magnetic tape and played back, the tape running is stopped and the recording or playback is temporarily interrupted, and then the tape is run again to continue to the previous recording track and a new recording is performed. There is a so-called joint shooting function that records signals. In this case, if the interval between the recording traces of the CTL signal, which is a control signal on the tape, is not constant at the joint between the previous recording trace and the subsequent recording on the tape, the tracking servo of this joint is continuously reproduced at this joint. Disturbance occurs and the playback screen becomes unstable. The present invention
A means for detecting the operation time of the pinch roller and a means for detecting the winding amount of the tape are provided, and the start timing of the recording operation is corrected by the detection outputs of the both means to reduce the mechanical delay time of the tape drive system. This is to reduce the error in the interval of the recording traces of the CTL signal caused by variations in the tape tension, which varies depending on the variation and the tape winding amount, so that a stable playback screen without tracking disturbance can be obtained.

[Conventional technology]

As a conventional technique, for example, there is a joint photographing method as shown in the system diagram of FIG.

This operation will be described below with reference to FIG. 4 and its operation timing chart of FIG. When the STOP button is pressed to stop the VRT from the one-cut recording state, the stop command signal 9 is supplied to the system control circuit 10 (point a in FIG. 5). At this time, pinch solenoid drive command signal 19
Is kept in the ON command state (Fig. 5- (3)), and the capstan rotation direction command signal 18 is a reverse rotation command (fifth command).
Figure- (2)). Therefore, while the pinch roller is pressed against the capstan, the capstan motor reverses and the tape is rewound by a certain amount. During this tape rewinding period, the mode command signal 17 is in the reproduction mode (Fig. 5-
(4)), the CTL signal reproduced by the CTL head 1 is amplified by the CTL reproduction amplifier 3 via the signal selection circuit 2, waveform-shaped and supplied to the counter 4. In the present embodiment, for example, the counter 4 sends a count end signal to the system control circuit 10 when it counts the CTL signal 6 times (FIG. 5-b).
point).

Pinch solenoid drive command signal 19 at point b shown in FIG.
As a result, a pinch OFF command is issued, and an OFF pulse is generated at the output of the solenoid ON / OFF pulse generation circuit 14 to turn off the crimping of the pinch solenoid 16 to the capstan via the solenoid drive circuit 15. Therefore, the pinch roller separates from the capstan and the tape running stops. That is, the tape rewind amount is always rewound by 6 frames, and the tape stop position is fixed at a fixed timing with respect to the position of the recorded CTL pulse and waits until the next cut is recorded. The capstan motor switches to the normal rotation at the same time as the pinch roller separates from the capstan at the point b as shown in FIG. 5 (2).

Next, when the start button is pressed to record a new cut, the start command signal 8 is supplied to the system control circuit 10. When the start command signal 8 is supplied, the system control circuit 10 outputs an ON command signal 19 in synchronization with the reference frame pulse 6, and an ON pulse is generated at the output of the solenoid ON / OFF pulse generation circuit 14 The pinch solenoid 16 is turned on via the drive circuit 15. That is, when the start button is pressed, the pinch roller is pressed against the capstan at the timing synchronized with the reference frame pulse to start the tape running. (FIG. 5- (3)). The counter 7 starts counting the reference frame pulse 6 from the time when the pinch solenoid is turned on.
When counting for the number of frames, a count end command is supplied to the system control circuit 10. (Fig. 5-point c). At the point c shown in FIG. 5, the mode command signal 17 is switched to the recording mode, the output signal of the CTL recording amplifier 5 is supplied to the CTL head 1 through the signal selection circuit 2, and the CTL signal for the next cut is recorded on the tape. . At the same time, the video and audio signals are supplied from the recording amplifier 11 to the video head 12 and the audio head 13 and recorded on the tape. Therefore, the CTL recording pattern is shown in Figure 5.
As shown in (5), a constant interval is maintained between cut A and cut B. Here, since the operation time of the pinch solenoid 16 is deviated from the track at the timing of switching to the recording mode at point c in FIG. 5 above, the timing is actually adjusted according to the operation time of the pinch solenoid.

[Problems to be solved by the invention]

In the above-mentioned conventional technology, when the VTR is driven by using the battery, the battery voltage naturally changes according to the operating time, but the operating time of the pinch solenoid changes with this voltage change, and as a result, the CTL signal is recorded. There is a drawback that the timing is off. Further, since the tape tension varies with the change in the tape winding amount, the position with respect to the reference timing signal is displaced when the tape is stopped or run. Therefore, also in this case, there is a drawback that the recording timing of the CTL signal is deviated. An object of the present invention is to eliminate these drawbacks, that is, the deviation of the recording timing of the CTL signal caused by the fluctuation of the battery voltage and the change of the tape winding amount.

[Means for solving problems]

In order to achieve the above object, the present invention comprises a voltage detection circuit for detecting a battery voltage and an arithmetic circuit for detecting a tape winding amount, and automatically detects a CTL according to a value of the battery voltage and a tape winding amount. By changing the recording timing of the signal, the interval of the recording traces of the CTL signal is kept constant. FIG. 1 is a block diagram showing the overall configuration of the present invention.

In the VTR of the present embodiment, when the tape is stopped by operating the stop button and the recording is put in the standby state, the pinch roller is not released from the capstan and the crimping state is maintained, and the tape is rotated by reversing the capstan motor. After returning to a predetermined length, the pinch roller is separated from the capstan to stop the tape running. At this time, the capstan motor always performs speed control and phase control in the recording mode. To detect the tape winding amount, a frequency generator (FG) that detects the rotation speed is provided on the supply reel motor and the take-up reel motor, and calculation is performed using these two FG signals.

[Action]

As a result, CT depending on battery voltage and tape winding amount
The correction data of the recording timing of the L signal is obtained, this data is supplied to the system circuit, and the recording mode is switched to by the corrected recording timing signal.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The embodiment of the present invention is the same as the embodiment 1-19 of the prior art shown in FIG.
20 to 26 are added. Reference numeral 26 denotes a switch (hereinafter referred to as SW) for detecting the ON state of the pinch solenoid 16, which turns ON when the pinch solenoid is turned ON, that is, when the pinch roller is pressed against the capstan. One of the terminals of SW 26 is connected to the solenoid operation time detection circuit 24, and this circuit 24 detects the operation time of the pinch solenoid. Output 25 of circuit 24
As shown in FIG. 2, the time T from when the start command signal 8 is supplied by pressing the start button of the VTR to when the SW 26 is turned on is detected. The pinch solenoid drive circuit 15 is generally a portable VTR because of the drive current of the solenoid.
In this case, since it is difficult to provide a large-capacity stabilized power source in terms of miniaturization and weight reduction, it is usual to directly supply the battery power source. In this case, since the battery voltage naturally changes depending on the usage time and the charging state, the driving voltage supplied to the solenoid 16 also changes. As a result, the operating time of the solenoid changes, so that the value of the time T shown in FIG. 2 changes. Assuming that the change in T is ΔT, the timing at the point c in FIG. 5 described above is shifted by ΔT, and as a result, the interval with the recording trace of the CTL signal is shifted at the joint. Therefore, the shift of ΔT is canceled by the recording timing correction calculation circuit 23. On the other hand, the take-up reel FG signal 20 and the supply reel FG signal 21 are supplied to the tape winding amount calculation circuit 22 to detect the tape winding amount. This winding amount is detected during recording of one cut. Since the tape running speed during recording is constant, the tape winding amount can be detected by calculating the ratio between the frequency of the supply reel FG signal and the frequency of the take-up reel FG signal. The tape winding amount information obtained by the tape winding amount calculating circuit 22 is supplied to the recording timing correction calculating circuit 23.

When the tape winding amount changes, the tape tension in the recording mode and the stop mode changes, so
As a result of the tape position shift at point b in FIG. 5, the timing at point c in FIG. 5 shifts as shown in FIG.
The intervals of signal traces are shifted at the joints. Therefore, the timing correction data corresponding to the tape winding amount is stored in advance in memory and the recording timing correction calculation circuit 23 compensates for the timing deviation. The circuits 22 and 23 are composed of a microcomputer and a ROM IC in this embodiment.

〔The invention's effect〕

According to the present invention, the capstan motor for running the tape is reversely rotated at the stop time to rewind the tape for a predetermined length, and then the pinch roller pressure release to the capstan is released to stop the tape running and wait for the next cut. At the start of recording, the pinch roller was pressed to start the recording operation on the tape at the position where it was run for a predetermined length in the forward direction.
In a VTR (magnetic recording device), it is designed to compensate for the gap at the joint between the recording traces of the CTL signal caused by the change in the battery voltage and the change in the tape tension with respect to the tape winding amount. According to the present invention, a stable reproduced image can be obtained without causing tracking disturbance when the joint is reproduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall structure of the present invention, FIG.
FIG. 3 is an explanatory diagram of the present invention, FIG. 4 is a block diagram showing a conventional example, and FIG. 5 is an operation explanatory diagram of the conventional example. 20: Take-up reel FG signal, 21: Supply reel FG signal, 22: Tape amount detection calculation circuit, 23: Recording timing correction calculation circuit, 24: Solenoid operation time detection circuit.

Claims (1)

[Claims] 1. A capstan motor for running a tape is reversely rotated at a stop to rewind the tape for a predetermined length, and then a pinch roller is separated from the capstan to stop the tape running and put into a standby state, and a pinch at the next start. In a VTR in which the roller is pressed onto the capstan and the recording operation is started at the position where the tape has run in the forward direction for a predetermined length,
A first means for detecting the operation time of the pinch roller and a second means for detecting the winding amount of the tape are provided, and the start timing of the recording operation is corrected by the detection outputs of the first means and the second means. This is a VTR connection method.