JPS6247895A - Video signal reproducer - Google Patents

Abstract

PURPOSE:To obtain surely a time code signal without using any mechanical constitution by obtaining a pulse signal for each field based on the reproduced video signal of a video track in case it is impossible to read the time code signal in a low-speed reproduction mode. CONSTITUTION:The time count signal TC is read out 10 of a signal PUTC that is picked up out of a time code track by a magnetic head and applied to a counter 12 via a gate 11. At the same time, a control pulse TCP and a tape driving direction signal FORE which are supplied for each filed are applied to the counter 12 via a gate 13. A tape speed signal SPD opens the gate 11 when the speed is set at such a level that can read completely the time code signal TCOUT and then opens the gate 13 when it may possibly unable to read the signal TCOUT. At a video signal reproduction part, a memory switching control circuit sends the control signal TCP to the gate 11 by the address code ADR of the termination of the final track TRV within a field. Thus it is possible to obtain the signal TCOUT without fail regardless of the mechanical constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a video signal reproducing device, and is particularly suitable for application to a digital video tape recorder (digital VTR).

B. Summary of the Invention The present invention provides a video signal reproducing device for reproducing a magnetic tape in which a time code track is formed in the longitudinal direction.
When the slow playback mode is selected and the time code signal cannot be read, a pulse signal is obtained for each field based on the playback video signal played from the video track.
By updating the time code signal obtained before selecting the low-speed playback mode, the time code signal can be reliably obtained in the low-speed playback mode without using a mechanical structure.

C. Conventional technology When editing a magnetic tape on which a video signal is recorded, it is important to know the position on the magnetic tape. I try to record it.

Conventionally, as a method for recording time code signals, as shown in FIG.
and one end VI on the video track TRV formed obliquely with respect to the longitudinal direction of the magnetic tape 1.
There is a way to record on TC.

In order to record on one end VIIC on the video track TRV, it is necessary to process the video signal so that it can record the time code signal at the same time, which avoids a complicated and large configuration. Therefore, there is a digital VTR that records a time code signal only in the tape longitudinal direction LTC.

D Problem to be Solved by the Invention However, when the low speed playback mode is selected and the tape runs at low speed, the time code signal is obtained from the pickup signal picked up by the magnetic head from the time code track LTC provided in the longitudinal direction of the tape. There is a risk that it will disappear. In practice, the tape speed is 115 times to 1/1 of the normal speed (tape speed in recording mode).
When the speed becomes 0x or lower, a time code signal cannot be obtained.

Conventionally, when a time code signal cannot be obtained, a detection signal is obtained every predetermined time (for example, field) recorded according to the distance traveled by the tape, and the last time code obtained from the pickup signal is A time code signal is output by updating the signal according to this detection signal. There is a method of using a control signal CTL picked up from a control track TRC provided in the longitudinal direction of the tape 1 as the detection signal at predetermined time intervals.

However, with this method, there is a risk that the control signal CTL itself may not be picked up accurately in low-speed playback mode, and the time code signal may not be updated even if the tape has traveled a distance corresponding to a predetermined recording time. be.

Furthermore, conventionally, the tape 1 is tilted at a predetermined angle (for example, 180 [
There is a method of obtaining a time code signal in a low-speed playback mode using a signal sent every predetermined travel distance of the tape 1 by a rotatable cylindrical timer roller that is wound by an angle of 100 degrees or more. However, this method has the disadvantage that the provision of the timer roller occupies space, which is a constraint on downsizing.
Further, there is a problem that the tape is damaged due to friction between the timer roller and the tape.

In order to solve these problems, in a digital VTR, it is possible to write a time code signal in the user's bit assigned to the user and record it on the video track, but in this way, the remaining user's bit that can be used publicly is There is a risk that the user's bits may decrease and become unusable for other purposes.

The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a video signal playback device that can reliably obtain a time code signal in low-speed playback mode without using any mechanical configuration. .

E Means for Solving Problem E To solve this problem, in the present invention, the time code track L provided in the longitudinal direction of the magnetic tape 1 is
Playback signal PUT from TC when the magnetic head jumps up
A time code reader 10 receives a time code signal TC and reads a time code signal TC, and opens when receiving a running speed signal SPD indicating that the tape speed is slower than a predetermined speed;
A first gate circuit 11 that passes the time code signal TC read by the time code reader 10, and a running speed signal SP that indicates that the tape speed is faster than a predetermined speed.
A second gate circuit 1 that opens when receiving a time code control pulse [TCP] that opens for each field formed based on the reproduction signal Via picked up from the video track on the magnetic tape 1.
3, and a time code control pulse signal T which receives the time code signal TC which has passed through the first gate circuit 11 at the load terminal and which has passed through the second gate circuit 13.
Receives CP to clock terminal and outputs time code signal TC
and a time code counter 12 that sends out ouy.

When a playback mode at a tape speed in which the time code signal TC can be read accurately is selected, the running speed signal S
Based on PD, the first gate circuit 11 opens and the second gate circuit 13 closes. At this time, the time code signal TC read from the pickup signal PUTC in the time code reader lO is sent out as the output time code signal TCouy via the time code counter 12.

On the other hand, if a low-speed playback mode is selected at a tape speed where the time code signal TC cannot be read, the running speed is 1.
The first gate circuit 11 operates to close based on No. 8 SPD,
The second gate circuit operates to open. As a result, the time code counter 12 updates the count value every time the time code control pulse signal TCP for each field arrives, and outputs the count value as the time code signal TC.
Send as ouy.

As a result, a time code signal can be reliably obtained even in low-speed playback mode.

Embodiment G An embodiment of the present invention will be described in detail below with reference to the drawings. 1st
In the figure, reference numeral 5 generally indicates a time code signal output section, and the output section 5 receives a pickup signal PUTC picked up by a magnetic head from a time code track LTC provided in the longitudinal direction of the tape 1 at a time code read tick 0.

The time code reader 10 extracts a clock signal from the pickup signal PUTC, reproduces the time code signal TC based on this clock signal, and supplies it to the load terminal of the time code counter 12 via the gate circuit 11. The time code counter 12 also receives a time code control pulse signal TCP that arrives for each field via a gate circuit 13 at its clock terminal, and receives a forward reverse signal FORE representing the forward and reverse directions of the tape running direction at its up and down terminals. It is designed to be given to

The gate circuits 11 and 13 receive a tape running speed signal SP.
D is given, and the opening operation is performed alternatively. The tape running speed signal SPD is, for example, a 1-bit signal, and the gate circuit 11 is opened when the tape speed is equal to or higher than the minimum tape speed at which the time code signal can be reliably read. When the tape speed is lower than that, that is, when the tape speed is such that there is a possibility that the time code signal cannot be read, the gate circuit 13 is opened.

The time code control pulse signal TCP is applied to the gate circuit 13 from the memory switching control circuit 31 shown in FIG. In FIG. 2, reference numeral 20 indicates a re-outgoing part of the video signal as a whole, and a reproduced video signal V given to the reproduction unit 20.
1 is converted into a parallel data signal in a serial-parallel conversion circuit 21, and then connected via a latch circuit 22 to first, second, and third field memories 2, each of which constitutes an image memory.
3.24.25 is input to the video signal memory 26. The first to third field memories 23 to 25 are controlled to write video data to a memory area having an address designated by a write address signal Sl generated by a write address counter 27. Here, the write address counter 27 sequentially performs a counting operation at the timing of the reproduction lock signal S3 from the address loaded by the address load signal S2 given from the memory switching control circuit 31.

Further, the first to third field memories 23 to 25 are adapted to read out the video data recorded in the memory area having the address specified by the successive address signal S4 of the successive address counter 28 at a predetermined timing. The successive address counter 28 is configured to start counting sequentially from the address loaded by the address load signal S5 given from the memory switching control circuit 31, thereby selecting the field to be read out of the first to third field memories 23 to 25. It is designed to specify memory.

The video data thus read out from the video signal memory 26 is sent out via the latch circuit 29 and further via the parallel-to-serial conversion circuit 30 as a reproduced output video signal VOtlA.

The reason why the video signal memory 26 is composed of three field memories 23 to 25 is because, as shown in FIG. The field MF has two scanning trajectories, (M+1
) may straddle the F track. That is, it is necessary to write the reproduced video signal picked up in one scan into two field memories separately, and
Another field memory is required to read data during the write operation, thus requiring a total of three field memories 23-25.

The memory switching control circuit 31 selects the field memories 23 to 25 to be used based on reproduction information S6 reproduced from the magnetic tape, such as an address code, and reproduction mode selection information S7 separately provided from an operation panel. that time,
The memory switching control circuit 31 controls the reading of data from the field memory in which data for one field has been written.

For example, as shown in Fig. 3, scanning is performed on the last track in one field (in a digital VTR, the video signal of one field is divided into multiple (10 or 12) tracks, and the last track). Address code area ADR (digital VT
In R, data is recorded through distributed processing in consideration of data dropouts, etc., so address codes are inserted in each unit block to restore the predetermined order during playback). After data is written in the memory area corresponding to the address, the memory switching control circuit 31 operates to read out the field memory immediately.

Therefore, since such an address code area ADR is provided for each field, the memory switching control circuit 3
1 performs switching control to read operation every time one field ends, and at the same time, memory switching control circuit 3
1 is the time code control pulse signal TC mentioned above.
P is sent to the gate circuit 13.

In the above configuration, when a playback mode in which the tape runs at a speed that allows the time code signal TC to be read more accurately than the playback signal picked up from the time code track LTC is selected, the gate circuit 11 is opened based on the running speed signal SPD. The gate circuit 13 operates to close.

At this time, in the time code reader 10, the playback signal P
The time code signal TC read from UTC is applied to the load terminal of the time code counter 12, and the applied time code signal TC is sent out as is as the output time code signal TCOLIT from the time code counter 12.

On the other hand, when a low-speed playback mode is selected in which the tape runs at such a speed that the timecode signal cannot be accurately read from the playback signal from the timecode track LTC, the gate circuit 11 closes based on the running speed signal SPD. On the other hand, the gate circuit 13 operates to open. At this time, a time code control pulse signal TCP is applied to the time code counter 12 from the memory switching control circuit 31 via the gate circuit 13 for each field.

The time code counter 12 updates the count value every time the time code control pulse P TCP is given based on the last time code signal given from the time code reader 10, and outputs the updated value as a time code signal TOOLIT. Send as.

Therefore, according to this embodiment, the time code track LT
Even in a low-speed playback mode in which time code cannot be obtained from C, a time code signal can be reliably obtained based on the address code, and editing points can be easily found when editing a videotape. In this way, since the time code signal is obtained without using any mechanical structure, it is possible to avoid increasing the size and complexity of the device.

Alternatively, it may be possible to form the time code control pulse signal TCP for updating the time code counter 12 based on the reproduced track code (inserted for each track), but in this case, the address is Compared to the case where a code is picked up, the track code area is narrower and the probability of picking it up is lower, and there is a possibility that the time code counter 12 cannot be updated reliably.

In the above description, a circuit that detects each field is combined with a memory switching control circuit 31 that controls the write address signal and successive address signal of the image information memory 16. Address code area ADR located at the end of scanning
A detection circuit that outputs a time code control pulse signal TCP when an address code is picked up from the address code may be provided separately, and the same effect as described above can also be obtained in this case.

H Effects of the Invention As described above, according to the present invention, in the low-speed playback mode in which the time code signal cannot be obtained from the pickup signal that picked up the signal recorded on the time code track, the field is Obtain a pulse signal for each pulse, and based on this pulse signal,
Since the output time code signal is obtained by updating the time code signal obtained based on the pickup signal from the time code track, the time code signal can be reliably obtained without using any mechanical configuration even in low-speed playback mode. Therefore, it is possible to obtain a video signal reproducing device with a simple configuration that can perform the following functions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a time code signal output section in an embodiment of the video signal reproducing device according to the present invention, and FIG.
The figure is a block diagram showing the video signal reproducing section, Figure 3 is a route map showing the relationship between the scanning locus of the magnetic head and the tape pattern, and Figure 4 is a route map for explaining the time code recording track. . 5... Time code output section, 1o...
・Time code reader, 11.13... Gate circuit, 12... Time code counter, Tc.
...Time code signal, SPD...Travel speed signal, TCP...Time code control pulse signal.

Claims (1)

[Scope of Claim] A time code reader that reads a time code signal by receiving a playback signal picked up by a magnetic head from a time code track provided in the longitudinal direction of a magnetic tape; a first gate circuit that opens when receiving a running speed signal to allow the time code signal read by the time code reader to pass; and the running speed, the tape speed being faster than the predetermined speed. a second gate circuit that opens when receiving a signal and passes a time code control pulse signal that appears for each field formed based on a playback signal picked up from a video track on the magnetic tape; a time code counter that receives the time code signal that has passed through the gate circuit at a load terminal, receives the time code control pulse signal that has passed through the second gate circuit at a clock terminal, and sends out an output time code signal. 1. A video signal reproducing device characterized by: