JP2540866B2 - Rotational phase controller - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rotary phase control device for a rotary system, and more particularly to a VT.
It is suitable for use in helical scan recording / playback machines such as R.

[Outline of Invention]

For each phase reference signal, measure the phase difference from the signal that represents the rotation phase, and output the error as valid only when the phase difference is within a predetermined value, even if the cycle between the reference and rotation is a non-integer multiple. , A phase control device with improved servo response performance by causing lock-in for each cycle of the phase reference signal.

[Conventional technology]

In VTR, when recording NTSC signal, the rotary head drum uses 30Hz frame pulse (1/2 of vertical sync signal).
Phase servo is applied with the divided signal).

On the other hand, in a VTR called a 4-head small diameter drum system in which the head drum diameter is reduced to 2/3 times and the tape winding angle is 270 ° without changing the recording format, the drum is 4
Since it is 5 rotations, the servo lock is applied at 15Hz which is the greatest common divisor with the reference signal of 30Hz.

[Problems to be solved by the invention]

In the 4-head small-diameter drum system, the pull-in speed of the phase servo diameter is half of the normal speed, and there is a problem in that the response to rising and disturbance is slow.

In view of this problem, an object of the present invention is to measure the phase error substantially in the cycle of the reference signal and synchronize the rotation system even if the rotation frequency is a non-integer multiple of the frequency of the phase reference signal. To do.

[Means for solving problems]

This is a device for controlling the rotation phase of the rotating part in which the cycle T _{1 of the} phase reference signal (V / 2, 30 Hz) and the rotation cycle T ₂ do not have an integral multiple relation in accordance with the phase of the phase reference signal.

A measuring means (time measuring circuit 12) is provided for measuring the phase difference φ between the phase reference signal (V / 2) and the signal representative of the rotation phase (PG pulse, 45 Hz) for each cycle T ₁ . Furthermore, When T ₁ = nT ₂ (0.5 <n <2), when | φ | <T ₀ , the phase difference φ is enabled and output to the phase servo loop, and when | φ |> T ₀ , the phase difference φ is invalid. The determination means (CPU 14) is provided.

[Action]

The rotation phase is locked (phase synchronized) only with the closest reference phase that satisfies | φ | <T ₀ . It is not necessary to measure the phase error at the cycle of the least common multiple of the cycle of the reference signal and the rotation cycle.
Since it is stochastically locked to any phase indicated by the pulse train of the phase reference signal, the response delay of the servo at the time of rising is improved.

〔Example〕

FIG. 1 is a schematic block diagram of a drum servo system of a 4-head small diameter drum VTR to which the present invention is applied. As shown in FIG. 3, this VTR has heads 1a, 2a, 1b and 2b for every 90 ° on the rotary head drum 3, and 180 ° facing pairs 1a and 1b have positive azimuth angles (+) and 2a. 2b has a negative azimuth angle (-). The magnetic tape 4 is wound around 270 °, and the drum 3 rotates at 45 times / second. 3/4 rotation (270 °)
Heads 1a (+), 2a (-), 1b (+), 2b for each
Switch to (-) in sequence and, as shown in Fig. 4, track T1
A, T2a, T1b ………… are recorded in azimuth.

In FIG. 1, the rotation phase of the drum motor 5 directly connected to the rotary drum 3 is the recording vertical synchronization signal (V
-SYNC, 60 Hz) is controlled to be synchronized with a reference signal (V / 2, 30 Hz in FIG. 2B) obtained by dividing the frequency by 1/2 by the 1/2 divider 10. The reason why the V-SYNC of 60 Hz is not used as the reference signal is that the vertical cycle of the output of the VTR, the video memory (VRAM), or the video game machine may differ from field to field.

A magnet piece M _PG for detecting a rotational phase is attached to the peripheral edge of the rotary drum 3, and a PG pulse (45 Hz, FIG. 2E) representative of the rotational phase is obtained from the fixed PG head 6. In addition, 6 magnet pieces for detecting rotation speed M _PG
Are attached to the peripheral edge of the drum at equal intervals, and an FG pulse (6 pulses / revolution) is obtained from the FG head 7 on the fixed side.

The output of the 1/2 frequency divider 10 and the outputs of the PG head 6 and the FG head 7 (V / 2, PG pulse, FG pulse) are supplied to the time measuring circuit 12 and the interrupt controller 13 in the servo circuit 11. The interrupt controller 13 sends the interrupt request signal IRQ and the corresponding interrupt vector IVC to the CP for each input of each output pulse.
Send to U14. Each time an interrupt occurs, the CPU 14 sends RA measurement data of the absolute time of each V / 2 pulse, PG pulse, and FG pulse.
Captured in M15, phase deviation based on the program in ROM16,
The speed deviation is calculated and an error signal (motor control signal) is output via the D / A converter 17. Error signal is drive amplifier
It is amplified at 18 and applied to the drum motor 5.

As shown in FIGS. 2E, F, and G, the phase relationship between the servo reference signal V / 2 of 30 Hz (FIG. 2B) and the PG pulse of 45 Hz is 3
Kind occurs. In E (state I), the V / 2 pulse in FIG. 2B and the PG pulse in FIG.
That is, the servo phase of the 15 Hz pulse V / 4 obtained by dividing the V-SYNC shown in FIG. 2D by 1/4 is matched. G (No. I
In the II state), the V / 2 pulse and the PG pulse match. That is, the servo phase is aligned with the V / 4 pulse shown in FIG. 2D.

The state II shown in FIG. 2F is an intermediate state between the states I and III, and the PG pulse and are in phase synchronization with the reference signal V / 2, or the PG pulse and V / 2 are in phase. It is divided into phase synchronization. And (or and) phase difference,
The absolute value of the phase difference from 2 is equal to T ₀ , and the polarities are opposite.

The first servo circuit 11 is used for the I and II of FIGS.
Operates so that any of the I states occur. Therefore, at the start-up, the servo system is effectively pulled to the phase reference point for each V / 20 (30 Hz). After locking,
V / 4 pulse period, that is, V / 2 (30Hz) and PG pulse (45H
z) Since the phases of the two only match at the maximum common divisor of 15Hz, feedback control of the servo loop is performed based on sampling every 15Hz.

In the intermediate state (II) of FIG. 2F, when the phase difference between and (or and) is smaller than T ₀ , the phase difference between and becomes larger than T _0. Phase control is performed so that they match. On the contrary, the second
When the phase difference between and of Fig. F is smaller than T ₀ , the phase difference between and becomes larger than T ₀ , and thus the phase control is performed so as to match with.

In either case, the phase difference is smaller than T ₀ at 15Hz
However, the lock point is calculated for all of the pulse train of the reference signal V / 2 of 30Hz, ... It becomes the servo operation like this.

Generally, the phase difference T ₀ in the above-mentioned intermediate state is given by assuming that the cycle of the reference signal is T ₁ and the rotation cycle of the rotating section that is the control target is T ₂ . T ₁ = nT ₂ (0.5 <n <2). In the embodiment, T ₁ = 1/30 sec, T ₂ = 1/45 sec, and T ₀ ≈
It is 5.6 msec. In this example, T ₁ > T ₂ , but T ₂ > T
The relationship of ₁ may be used, and when n is 2 or more or 0.5 or less, the pulse with the higher frequency may be divided to satisfy the relationship of 0.5 <n <2.

FIG. 5 shows a phase servo algorithm (interrupt routine) executed by the CPU 14 of FIG. In steps S1 and S3, the arrival of the reference signal V / 2 and the PG pulse is awaited. V / 2
Comes in, take in the absolute time T _V at that time in step S2,
When the PG pulse comes, set the absolute time T _{PG at} that time to step S4
Take in. Next, in step S5, the phase difference φ is calculated by the formula T _PG −T _V.

The calculated phase difference φ is between φ in FIG.
_It is correct when ₁ is measured, but the next time φ ₂ between is measured, it must be converted into φ ₂ ′ between. When this order phi in step S6 determines that greater than 1/60 (sec) (case of phi _2), in step S7 phi
-1/30 (sec), that is, φ ₂ ′ conversion. By the processes of steps S5 and S6, the measurement of the phase difference φ (the dynamic range of the data) is performed for each pulse of FIG. 2B, ...
Range of ± 1/60 (sec) centered on ……, D _a , D _b , D _c ……
Limited to ...

Next, in step S8, it is determined that | φ | is smaller than T _{0. When} this condition is satisfied, φ is output as a phase error to the D / A converter 17 in FIG. 1 in step S9. Also | φ
When | is larger than T ₀ , φ is not recognized as an error and ignored. Therefore, when the PG pulse having the phase as shown in FIG.
The phase differences φ ₁ and φ _{4 of} are output to the servo loop as valid error data, and the phase differences φ ₂ and φ _{3 of}
Is disabled. For this reason, a servo operation is performed so as to pull in or into the phase of or.

When the PG pulse as shown in FIG. 2I is generated, only the phase difference φ ₂ is valid, and φ ₁ , φ ₃ , and φ ₄ are invalid.

In this way, the servo pull-in at start-up is based on the reference signal V /
The lock-in speed is twice as high as that of the conventional sampling every 15 Hz because it occurs equally for any phase of 2 (30 Hz) pulse, .... Measurement of phase error
Every 30Hz in the CPU, 15Hz in the whole servo loop
Every sampling interval is set.

〔The invention's effect〕

As described above, the present invention measures the phase difference from the signal representative of the rotational phase for each phase reference signal and validates it as a servo error only when the phase difference is within a predetermined value. It is possible to significantly improve the response performance of the phase servo with a simple configuration, as compared with the conventional technology in which the phase error is generated in the cycle of the phase reference signal and the phase error is measured in the cycle of the least common multiple of the reference cycle and the rotation cycle. .

[Brief description of drawings]

FIG. 1 is a drum servo circuit diagram of a 4-head VTR to which the present invention is applied, FIG. 2 is a phase servo time chart, FIG. 3 is a schematic diagram of a 4-head drum, and FIG. 4 is a recording pattern diagram on a tape. FIG. 5 is a flowchart showing the algorithm of the phase servo. In the reference numerals used in the drawings, 1a, 1b, 2a, 2b ... rotary head 3 ... rotary head drum 4 ... magnetic tape 5 ... drum motor 6 ... PG head 7 ... FG head 11 ... servo circuit 12 …… Time measuring circuit 14 …… CPU 15 …… RAM 16 …… ROM 17 …… D / A converter.

Claims (1)

(57) [Claims] 1. A device for controlling a rotation phase of a rotating part, which is not an integral multiple relation between a cycle T ₁ of the phase reference signal and a rotation cycle T _2, according to the phase of the phase reference signal, wherein the phase reference signal and the rotation phase Measuring means for measuring the phase difference φ with a signal representative of every period T ₁ , When T ₁ = nT ₂ (0.5 <n <2), when | φ | <T ₀ , the phase difference φ is enabled and output to the phase servo loop, and when | φ |> T ₀ , the phase difference φ is invalid. And a rotation phase control device.