JP2550676B2 - VTR - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a portable VTR, for example, which is capable of performing joint shooting.

[Outline of Invention]

The present invention relates to a VTR, in which a rise time of a capstan motor is measured and a drive start timing of the capstan motor is formed based on the rise time so that a good joint shot is performed.

[Conventional technology]

For example, when performing a joint shot with a portable VTR, the tape is rewound by a predetermined amount before the joint shot is started, and playback is performed, and adjustment is performed so that the phase of the playback CTL signal and the predetermined reference synchronization signal match. Going forward, it is being carried out to realize continuous shots without CTL pitch disturbance.

However, the above-mentioned adjustment may take an extremely large amount depending on the initial phase difference, and if the rewinding amount is determined in consideration of the time, quick joint shooting cannot be performed.

Therefore, it is considered that the rise time of the capstan motor is measured and the drive start timing of the capstan motor is adjusted so that the phase of the reproduction CTL signal after the rise substantially matches the reference synchronization signal.

[Problems to be Solved by the Invention]

However, the rise time of the capstan motor described above largely varies from motor to motor, and adjustment is performed while observing the waveform of the reproduction signal in the adjustment process during manufacturing in the related art, but it requires skill and requires high accuracy. It was also difficult to make adjustments.

Even with such adjustment, the rise time may change due to changes in the surrounding environment, battery voltage drop, and changes over time.Therefore, it is necessary to provide a temperature center and voltage detection circuit to correct these rise times. Occurs,
Further, such a correction could not be performed for the change with time.

The present application has been made in view of such points.

[Means for solving the problem]

The first means for solving the problems in the present invention is
The rise time of the capstan motor is measured, the timing delay amount from a predetermined reference synchronization signal is calculated using this rise time, the calculation result is saved, and the saved delay amount is used to CTL is formed by forming the drive start timing of the capstan motor.
VT that enables continuous shots with stable pitch
R.

A second means constantly measures the rise time of the capstan motor in the VTR of the first means and corrects the drive start timing of the capstan motor at the time of the joint shooting using the measured value. It is a VTR that is supposed to do.

[Action]

According to this, since the rise time of the capstan motor is measured and the drive start timing is formed based on this rise time, it is possible to form highly accurate timing with a simple configuration. You can take continuous shots. Further, by always measuring the rise time, it is possible to easily correct the timing with respect to a change with time or the like.

〔Example〕

FIG. 1 is a block diagram showing the functions of essential parts. In the figure, when the capstan on command signal from the terminal (1) is supplied to the timing forming block (2), the reference frame synchronization signal from the terminal (3) A driving start timing of a predetermined delay time T _D is formed for the above, and this timing is supplied to the block (4) of the capstan servo to drive the capstan motor (5).

Therefore, for example, when the capstan-on command signal as shown in FIG. 2B is supplied to the reference frame sync signal as shown in FIG. 2A, the delay time T starts from the timing of the next sync signal. _D is provided, and the timing to start driving the capstan motor (5) is formed. When this timing is supplied to the block (4) and the capstan motor (5) is driven, a servo error signal due to the rotation of the motor (5) is generated as shown in FIG. Then, at the timing after the rise time of the motor (5) from the timing, the phases of the reproduction CTL signal and the reference frame synchronization signal (A in the same figure) shown in FIG. 13E are substantially matched, and the phases are synchronized by performing servo thereafter. It Further, after a predetermined time when this phase is synchronized, the recording of CTL is started as shown in FIG. 7C, so that the continuous shooting without disturbance of the CTL pitch is realized. The CTL recording may be performed at the same time as the CTL inversion, but more stable recording can be performed by overwriting a part of the CTL slightly before.

And in this time chart, timing →
The time of is a fixed time (for example, 9VD = 150msec.) Which is determined by the reference frame sync signal, but the time of timing → varies depending on the motor, so the delay time
I had to adjust T _D.

However, if the time T of the timing → can be measured in this time chart, it is possible to obtain the required delay time T _D by subtracting this time T from the time of the timing →, for example, 150 msec.

Therefore, in the above device, the timing from the block (2) is supplied to the block (6) of the counter to start counting. On the other hand, by driving the capstan motor (5), the previously recorded CTL is reproduced,
This reproduction signal is supplied from the terminal (7) to the switch (8). Further, the output of the frequency generator (FG) driven by the motor (5) is supplied from the terminal (9) to the speed detection block (10), and the switch is activated when the rotation speed of the motor (5) becomes close to the target. (8) is turned on. Then, the reproduction CTL signal from the switch (8) is supplied to the counter block (6) to stop the counting.

As a result, the count value corresponding to the timing → is obtained. This count value is supplied to the delay amount calculation block (11) to calculate the delay time T _D. Then, this calculation result is passed through the switch (12) to E ² PR.
It is supplied to the backup means (13) composed of OM, volume, etc., and the value corresponding to the delay time T _D is stored.

That is, at the time of adjustment, the switch (12) is turned on, the block (2) is set to an arbitrary delay time, and the capstan on command signal is supplied to the terminal (1).
As a result, the rising time T of the motor (5) at the timing → is measured in the block (6), and the desired delay time T _D is calculated in the block (11). Further, this measurement is repeated eight times, for example, and the average calculation result is stored in the backup means (13).

Therefore, during the normal operation, the stored value is supplied to the block (2) through the adder / subtractor (14) to form the drive start timing based on the delay time T _D.

Further, in the above device, when the rise time of the motor (5) varies due to changes in the surrounding environment, a decrease in battery voltage, changes over time, etc., the measurement by the block (6) of the counter is always performed, This measured value is supplied to the correction value calculation block (15), and the rise time calculation block (16) performs the reverse calculation to the block (11) from the value stored in the backup means (13). The calculation result is supplied to the block (15). Then, the block (15) can calculate the difference between the values, that is, the correction value, and supply the correction value to the adder / subtractor (14) to perform the correction.

Thus, according to the above apparatus, the rise time of the capstan motor is measured, and the drive start timing is formed based on this rise time. Therefore, highly accurate timing can be formed with a simple configuration. Therefore, it is possible to perform good joint shooting. Further, by always measuring the rise time, it is possible to easily correct the timing with respect to a change with time or the like.

In the above-mentioned device, each functional block can be formed, for example, as software of a microcomputer, which allows the above-mentioned device to be realized without providing a new circuit device or the like.

Further, in the above-mentioned device, the blocks of (15) and (16) may not be provided when the influence of aging or the like is small, and the value is supplied to the backup means (13) by another method. In some cases, block (11) becomes unnecessary. However, when these are provided by software as described above, the burden is hardly increased even if they are provided together.

〔The invention's effect〕

According to the present invention, the rise time of the capstan motor is measured, and the drive start timing is formed based on this rise time. Therefore, it is possible to form highly accurate timing with a simple configuration. Good joint photography can be performed. Further, by constantly measuring the rise time, it has become possible to easily correct the timing with respect to changes over time.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, and FIG. 2 is a diagram for explaining the same. (1), (3), (7) and (9) are terminals, (2) is a timing formation block, (4) is a capstan servo block, (5) is a capstan motor, and (6) is a counter block, (8) (12) is a switch, (10) is a speed detection block, (11) is a delay amount calculation block,
(13) is backup means, (14) is adder / subtractor, (15)
Is a correction value calculation block, and (16) is a rise time calculation block.

Claims (2)

(57) [Claims] 1. A rise time of a capstan motor is measured, a timing delay amount from a predetermined reference synchronization signal is calculated by using this rise time, and a result of the calculation is stored, and the stored delay is stored. A VTR that uses the amount to form the timing for starting the drive of the capstan motor to realize a continuous shot with a stable CTL pitch. 2. The VTR according to claim 1, wherein the rise time of the capstan motor is constantly measured, and the measured value is used to start driving of the capstan motor during the joint shooting. Corrected the timing
VTR.