JPH05128656A - Motor servo controller - Google Patents

Abstract

PURPOSE:To provide a control method at the time of starting a capstan obtaining a stable reproduced screen in a short time. CONSTITUTION:Respective numbers of revolution and phases are detected by the FG33 of the capstan and the FG37 and the PG38 of a drum, and are supplied to a detection process part 41. Further, a control signal is regenerated from a previously recorded tape in an ACE head 39 and supplied to the detection process part 41. The waveform of the supplied signal is shaped by the detection process part 41 and the signal is supplied to a control part 40. A deviation value corresponding to a phase difference between the control signal and the head on the drum is detected from the supplied signal by the control part 40. A capstan motor 34 and a drum motor 36 are controlled so that the deviation value is eliminated when the starting of the capstan is ended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor servo control device for a helical scan type magnetic recording / reproducing device (hereinafter referred to as VTR), and particularly, when a stop mode is changed to a reproducing mode, a stable reproducing screen is obtained in a short time. The present invention relates to the obtained motor servo control device.

[0002]

2. Description of the Related Art VTR servo mechanisms include a drum servo mechanism, a capstan servo mechanism, and a reel servo mechanism. Of these, control of the drum servo mechanism and the capstan servo mechanism is particularly important when shifting from the stop mode to the reproduction mode.

A conventional servo control method will be described below with reference to the drawings. FIG. 9 is a diagram showing the rotational speed of the capstan under servo control when shifting from the conventional stop mode to the reproduction mode. At first, the AFC servo is performed to raise the rotation speed of the capstan to the speed of the reproduction mode. Next, APC servo is performed to match the rotation phase of the drum and the phase of the control signal of the tape. In this way, two-step servo control was performed. For this reason, it takes a long time from the end of the rise of the capstan rotation speed to the end of the APC servo, and thus it takes a long time to obtain a stable screen after shifting to the reproduction mode.

[0004]

As described above, the conventional servo control at the time of shifting from the stop mode to the reproduction mode is a two-step servo in which the APC servo is performed after the AFC servo is completed. In this case, the time required from the end of the rise of the capstan rotation speed to the end of the APC servo is affected, and it takes a long time to obtain a stable reproduction screen after shifting to the reproduction mode.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a motor servo control device capable of obtaining a stable reproduction screen in a short time.

[0006]

The means according to the present invention comprises a first rotational speed detecting means for detecting the rotational speed of a capstan, a second rotational speed detecting means for detecting the rotational speed of a drum, and Phase detection means for detecting the phase of the head installed on the drum, recording / reproducing means for recording / reproducing a control signal with respect to the magnetic tape, control means for controlling the number of rotations of the capstan and the drum, A control means for detecting a shift amount corresponding to a phase difference between the control signal and the head on the tape, so that the shift amount detected by the detection means disappears at the end of the rising of the capstan. By controlling the number of rotations of the capstan and the drum with, a quick and stable image is provided.

[0007]

When the reproduction mode is designated, the amount of deviation corresponding to the phase difference between the control signal and the head is detected on the magnetic tape. Based on this amount of deviation, the number of revolutions of the capstan, and the number of revolutions of the drum, the amount of displacement disappears at the end of rising of the capstan, that is, the number of revolutions of the capstan or the drum is controlled so that the phase of the control signal and the head are synchronized. ..

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of a tape drive system will be described before describing the signal processing structure of the present invention. FIG. 8 is an explanatory diagram illustrating the configuration of a tape drive system. During reproduction and fast-forwarding, the tape supplied from the supply reel 10 is pressure-bonded to the drum 13 via the tension post 11 and the FE head 12. The tape leaving the drum 13 passes through the ACE head 14, the capstan 15, the pinch roller 16, the tilt guide 17, and the tension post 19 and then the take-up reel 2
It is wound up to 0. Further, at the time of rewinding, it is taken up by the supply reel 10 after going through the reverse process from the take-up reel 20. Of these, the supply reel 10, the take-up reel 20, the capstan 1
5 and the drum 13 detect data such as the tape speed and rotation speed.

Next, the signal processing configuration of the present invention will be described with reference to FIG. In FIG. 1, the video signal is a video signal processing unit 1
Is processed by. The video signal input to the A / D (analog / digital) converter 42 is converted into a digital signal and temporarily stored in the memory 43. The signal output from the memory 43 is a D / A (digital / analog) converter 4
It is supplied to the image processing unit 45 via 4 and is converted into a recording signal. This recording signal is recorded on a tape (not shown) via the recording head 46.

On the other hand, when reproducing a signal from a tape, the signal read by the reproducing head 47 is waveform-shaped by the image processing unit 45 and converted into a digital signal by the A / D converter 48. After being temporarily stored in the memory 43, the D / A
The converter 49 converts the analog video signal and outputs the analog video signal.

In addition to the above-mentioned video signal processing system, drive system signal processing is also performed. When the drive mode is specified for the control unit 40, the control unit 40 supplies the supply reel motor 30, the take-up reel motor 32, the capstan motor 34, the drum motor 36, and the AC.
A control signal for driving and controlling each of the E heads 39 is output. Each motor is driven by this control signal, and the ACE head 39 reads out or records the time code signal and the control signal.

Here, the supply reel motor 30, the take-up reel motor 32, the capstan motor 34, and the drum motor 36 are FGs which are devices for detecting the rotational speed.
Is attached. A PG, which is a device for detecting the phase, is also attached to the drum motor 36. The rotation speed signal and the phase signal of the motor detected by these FG and PF are supplied to the detection processing unit 41. The time code signal and control signal read by the ACE head 39 are also supplied to the detection processing unit 41.

The signal supplied to the detection processing section 41 is waveform-shaped and supplied to the control section 40. The control unit 40 controls the speed and phase of each motor based on the supplied signal, and matches the rotational phase of the drum motor 36, the tape phase and the tape speed with respect to the control signal.

Next, the positional relationship of the rotary head drum of the UNIHI type high-definition VTR will be described with reference to FIG. 2A is a sectional view of the rotary head drum, FIG. 2B is a side view of the rotary head drum, and FIG. 2C is an enlarged view of a portion Z in FIG. 2B. The UNIHI rotary head drum has four recording heads (RP) A1, B1, A2, B2 and 4 recording heads (RP).
Playback heads (PB) A1 ″, B1 ″, A2 ″, B2 ″
It is equipped with other heads. Of these heads, A1 and A2 and B1 and B2 are 180 °
Are placed in inverted positions, and again A1 and B1,
A2 and B2 are arranged so as to be separated by a width X and a height Y at their respective center positions. Such a relationship also applies to the four reproducing heads.

FIG. 3 shows a UNIHI tape pattern. In this figure, the audio signal, control signal and time code signal recorded on the upper and lower parts of the tape are recorded and reproduced by the ACE head. on the other hand,
Segment signals and multi-channel signals are recorded in the central portion of the tape. In the UNIHI system, the rotary head drum has a "six recording tracks / one field screen" in which one field screen is recorded or reproduced in one and a half rotations. Here, the recording tracks are traced by the corresponding reproducing heads. For example, the track recorded by the recording head A1 is traced by the reproducing head A1 ".

Next, with reference to FIGS. 4 and 5, the relationship between the tape pattern and the head trace in the initial stage of the rising of the capstan drive will be described. Of these, FIG. 4 is a diagram showing the relationship between the tape pattern and the head trace at the initial stage of rising of the capstan drive, and FIG. 5 shows the tape position and the RF signal reproduced by the reproducing head at the initial stage of rising of the capstan drive. It is a figure which shows the relationship with a maximum position.

As shown in FIG. 4, since the tape is hardly traveling at the initial stage of the rising of the capstan drive, the reproducing head of the rotary head drum traces the recorded pattern on the tape obliquely. In this case, as shown in FIG. 5, the RF signal of Ho at the end of the head trace is the maximum, and the RF signal of Hi at the start of the head trace is the minimum. Then, for the control signal, 1 /
You can see that it is repeated every 6 frames. That is R
There are 6 positions where the maximum value of the F signal is detected within one frame (three positions within one field). In the UNIHI system, a segment signal corresponding to each track is recorded at the head trace start position in the tape pattern. From this segment signal and the position where the maximum value of the RF signal is detected, the tape position at that time is detected, and at the same time, an accurate deviation amount L of the tape position can be obtained.

As a method of matching the rotational phase of the drum, the tape phase with respect to the control signal, and the tape speed by using the obtained deviation amount L, a method of controlling the rising speed of the capstan and a method of controlling the rising speed of the drum are used. And there is a way to control the rising speed of both the capstan and the drum. Here, a method of controlling the rising speed of the capstan will be described.

FIG. 6 shows a time chart of phase tuning by capstan control. In FIG. 6, (a) is a drum switching signal which is an FG output signal of the drum,
(B) is a control switching signal according to a conventional method among control switching signals obtained by waveform-processing the control signal, (c) is a control signal according to the embodiment, and (d) is a rotation speed of the capstan.

When the phase tuning was performed by the conventional method, the rotational speed of the capstan did not converge as shown by the broken line (d). On the other hand, in the present invention, the rotation speed of the capstan converges without overflowing as shown by the solid line in (d). Such a control method will be described with reference to the drawings.

When the deviation amount L of the current tape position is calculated
When the rotational speed of the capstan at (t1) is Np and the rotational speed of the capstan after convergence is Nl, Np is equal to Nl.
The time ts until it rises is expressed by equation (1).

[0022]

[Equation 1]

Of these, J is the inertia of the capstan, α is the torque constant of the capstan motor, and I
Is the current value applied to the capstan motor, Io
Is the no-load rotation current value.

If the time from the first rise of the drum switching signal after the reproduction mode is designated to the calculation of the shift amount is tp, and the carrying time after the rise of the capstan is tr, the phase of the drum switching signal and the control switching signal will be described. The time tm before synchronization is (2)
It becomes like a formula. tm = tp + ts + tr = nd.times.td (2) where nd is a constant determined by the capstan rising ability, and td is one period of the drum switching signal.

By the way, the tape moving distance S until the number of rotations of the capstan rises from Np to Nl is given by the equation (3). S = k.times.ts (1 + Np / Nl) / 2 (3) where k is the tape speed in the reproduction mode after speed convergence.

On the other hand, as can be seen from FIG. 6, the drum switching signal after phase synchronization and the control switching signal correspond to one cycle of the control switch signal to three cycles of the drum switching signal. From this, after the reproduction mode is designated, the tape movement distance Se from the first rise of the drum switching signal to the end of the phase synchronization is expressed by the equation (4). Se = S + k.times.tr = k (L + nc / 3fc) (4) Of these, nc is a constant determined by the capstan rising ability, and fc is the frequency of the control switching signal. The expression (5) can be obtained by rearranging the expressions (1) to (4) described above.

[0027]

[Equation 2]

By supplying the current as shown in the equation (5) to the capstan motor, the phase synchronization can be performed quickly. In addition, in order to respond to changes in business events and environmental changes,
If a training function is added, reliable control can be performed.

As described above, in addition to the method of controlling the rising speed of the capstan, there is a method of measuring the phase synchronization by controlling the rotation of the drum. This method will be described with reference to FIG. FIG. 7 is an explanatory diagram illustrating a method of controlling the rotation of the drum and measuring the phase synchronization. Of these (a)
Is the drum switching signal of the conventional method, and (b)
Is a drum switching signal of the embodiment, (c) is a control switching signal, (d) is a capstan rotation speed, and (e) is a drum rotation speed.

As shown in FIG. 7, the capstan rotation speed converges to a constant speed by changing the rotation speed of the drum in accordance with the phase shift, and at the same time, the phase between the drum switching signal and the capstan switching signal is changed. You can synchronize. As described above, the drum rotation control and the capstan rotation control may be performed at the same time. Further, in the case of the UNIHI system, it is impossible to specify the deviation amount L of the tape position without segment information.
However, in the case of the 1-track / 1-field recording method, R
Only by detecting the maximum position of the F output, the shift amount L of the tape position can be specified. In addition, paying attention to the signal change of the RF output at a specific position in the initial stage when the capstan drive is started and the tape transportation is started, and the shift amount L of the tape position is reached when the output at the specific position becomes maximum. Can also be calculated.

After the reproduction mode is instructed as described above, the deviation amount L of the current tape position is calculated in the initial stage of the tape transportation. Then, the shift amount L is compared with the capstan rotation speed and the drum rotation phase, and when the capstan rotation speed becomes equal to the rotation speed after the convergence of the reproduction mode, the phase of the control signal and the phase of the drum head are compared. Synchronize. This can provide a stable image quickly.

[0032]

As described above, after the playback mode is instructed, the shift amount of the current tape position is calculated in the initial stage of the tape feeding, and the shift amount, the capstan rotation number, and the drum rotation phase are calculated. In comparison, by synchronizing the phase of the control signal and the phase of the head of the drum when the capstan rotation speed becomes the same as the rotation speed after the convergence of the reproduction mode, it is possible to provide a quick and stable image. ..

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a UNIHI rotary head drum.

FIG. 3 is an explanatory diagram illustrating a UNIHI tape pattern.

FIG. 4 is an explanatory diagram illustrating a relationship between a tape pattern and a head trace.

FIG. 5 is an explanatory diagram illustrating a relationship between a tape position and a maximum position of an RF signal.

FIG. 6 is a time chart showing phase synchronization by capstan control.

FIG. 7 is an explanatory diagram illustrating phase synchronization by drum rotation control.

FIG. 8 is an explanatory diagram illustrating a configuration of a tape drive system.

FIG. 9 is an explanatory diagram illustrating a conventional capstan servo.

[Explanation of symbols]

 1 ... Image signal processing unit 30 ... Supply reel motor 31, 33, 35, 37 ... FG 32 ... Winding reel motor 34 ... Capstan motor 36 ... Drum motor 38 ... PG 39 ... ACE head 40 ... Control unit 41 ... Detection processing unit

Claims (1)

[Claims] 1. A first rotation speed detecting means for detecting a rotation speed of a capstan, a second rotation speed detecting means for detecting a rotation speed of a drum, and a phase of a head installed on the drum. Phase detecting means, recording / reproducing means for recording / reproducing a control signal to / from a magnetic tape, control means for controlling the number of rotations of the capstan and the drum, and the control signal and the head on the tape. A detecting means for detecting a shift amount corresponding to the phase difference, and the control means controls the rotational speed of the capstan or the drum so that the shift amount detected by the detecting means disappears at the end of the rising of the capstan. A motor servo control device characterized by controlling.