JPH09251682A - Device and method for controlling tape traveling speed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the traveling speed control covering the range from low speed to high speed when the high speed traveling of FF(fast-feeding)/REW (rewinding), etc., is executed, and also to execute the stable low speed traveling. SOLUTION: In the case the device is provided with a reel motor FG control part 2 and a tape speed control part 3, when the FF/REW is performed, the low speed traveling control is executed at first by the control of the reel motor FG control part 2 so that the reel motor 1 is rotated at a prescribed rotating period. Next, the acceleration is started and the high speed running control is executed by the control of the tape speed control part 3 so that the tape speed becomes a prescribed speed. When the tape comes close to the tape end, the speed reduction is started, and by control of the reel motor FG control part 2, the low speed traveling control is executed again, and the tape is stopped after that.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video tape recorder (hereinafter referred to as VTR) and a digital audio tape recorder (hereinafter referred to as DAT).
, Etc., and more specifically, to high-speed running control of a magnetic tape.

[0002]

2. Description of the Related Art A digital VTR for recording / reproducing a compression-encoded video signal on a magnetic tape together with an encoded audio signal is known (for example, Yukio Kubota's book "Illustrated Digital Video Reader", Ohmsha Co., Ltd.). Heisei 7
Issued on August 25, 2013). In this digital VTR,
A sub-code is recorded together with a video signal and an audio signal. The sub-code has a specified format so that the content can be read even when the magnetic tape is run at a speed about 200 times the recording speed. (P.95-9 of “Illustrated Digital Video Reader” above)
6).

[0003]

Conventionally, as a mode in which a magnetic tape is run at a high speed of several hundred times the recording speed in a VTR, FF (Fast Forward) is used.
There is / REW (Rewind), and in that mode, the magnetic tape is run at high speed by rotating the reel motor at high speed. However, in this case, since the video signal is not reproduced, the control for keeping the speed of the magnetic tape constant is not performed.

In addition, as a mode for running the magnetic tape at a high speed of several tens of times of the recording speed in the VTR, there is a queue /
There is a review, and the capstan motor is rotating in this mode. In this case, since the video signal is reproduced, control is performed so that the speed of the magnetic tape becomes constant. Speed control by capstan servo is 50
The limit is about twice.

Therefore, when the subcode of the digital VTR described above is read at high speed, the same control by the reel motor as in FF / REW is required. There are two possible control methods for controlling the running speed of the magnetic tape by driving the reel motor. The first method is to detect the running speed of the magnetic tape from the rotation cycle of the reel stand and control it so as to reach a target value. The second method is reel motor FG (Frequency).
The frequency of the generator is controlled so as to reach the target value.

When the magnetic tape is run at a speed of about 200 times, if it is run to the top or the end of the magnetic tape at a high speed, a so-called gut-stop state occurs, which damages the tape and causes the tape to break. It is necessary to drive at low speed near the top or end. That is, it is necessary to control the speed of the magnetic tape over a wide operating range from low speed to high speed.

However, in the first method, when the speed becomes low, the rotation cycle of the reel stand becomes long and the measurement time becomes long, so that the control becomes difficult. In the second method, the reel motor FG has several hundreds of reels (for example, 40 reels).
Since it has a frequency of 0), it is easy to control even at low speeds, but if you keep the number of rotations of the reel motor constant,
The running speed of the magnetic tape changes depending on the winding diameter of the reel. Therefore, in order to keep the running speed of the magnetic tape constant, complicated processing such as gradually changing the target value of the number of rotations of the reel motor according to the winding diameter is required.

The present invention has been made in view of the above problems, and provides a magnetic tape running speed control apparatus and method for easily controlling the running speed of a magnetic tape from low speed to high speed. With the goal.

[0009]

In order to solve the above problems, a magnetic tape running speed control apparatus according to the present invention is a running speed of a magnetic tape in an apparatus for reproducing data recorded on an oblique track of a magnetic tape. A device for controlling the magnetic tape, a means for detecting the running speed of the magnetic tape, a means for detecting the number of revolutions of the motor, and a means for generating a reference signal for controlling the motor. And a means for generating a reference signal for controlling the motor has a first mode in which the traveling speed of the magnetic tape is constant and a second mode in which the rotation speed of the motor is constant. It is what

A magnetic tape running speed control method according to the present invention is a method for controlling a running speed of a magnetic tape in an apparatus for reproducing data recorded on an oblique track of the magnetic tape. When the speed is less than a predetermined value, the rotation speed of the motor that drives the magnetic tape is controlled to be constant, and when the speed of the magnetic tape exceeds a predetermined value, the speed of the magnetic tape is controlled to be constant. It is characterized by doing.

According to the present invention, when the running speed of the magnetic tape is below a predetermined value, the rotation speed of the motor for running the magnetic tape is controlled to be constant, and when the running speed of the magnetic tape exceeds the predetermined value. The magnetic tape is controlled so that the traveling speed is constant.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a tape traveling speed control device to which the present invention is applied. In this device, the running speed of the magnetic tape is changed from about 40 times to 200 times that at the time of recording by controlling the speed of the reel motor.

This tape running speed control device includes a reel motor 1, a reel motor FG control unit 2, a tape speed control unit 3, a tape speed detection unit 4, a control reference value generation unit 5, and a reel motor FG control. A switch SW for selecting the output of the section 2 and the output of the tape speed control section 3 and inputting them to the reel motor 1 is provided. In addition, this tape running speed control device detects the rotation cycle of the reel table of the S reel by using the S reel FG generated in response to the rotation of the reel table of the supply reel (hereinafter referred to as the S reel). A cycle measuring unit 6T that detects the rotation cycle of the reel unit of the T reel by using the measuring unit 6S and the T reel FG generated in response to the rotation of the take-up reel reel unit (hereinafter referred to as T reel). It has and. Here, parts other than the reel motor 1 are configured by software of a microcomputer (hereinafter referred to as a microcomputer).

The reel motor 1 drives the T reel.
Further, the reel motor FG corresponding to the rotation of the reel motor 1 is output. The reel motor FG is input to the reel motor FG control unit 2. The final target speed (for example, 200 times) is input to the control reference value generation unit 5 at the time of startup.

The reel motor FG control unit 2 divides the reel motor FG by a frequency dividing unit 21, a period measuring unit 22 that measures the period of an output signal of the frequency dividing unit 21, and a period measuring unit 2
A subtraction unit 23 that subtracts the reference period output from the control reference value generation unit 5 from the output of 2 and an error calculation unit 24 that calculates an error signal for driving the reel motor 1 based on the output of the subtraction unit 23. ing. The reel motor FG control unit 2 controls the reel motor 1 to rotate at a predetermined cycle (details will be described later).

The tape speed control unit 3 uses the tape speed detected by the tape speed detection unit 4 to generate a control reference value generation unit 5.
Subtractor 31 for subtracting the reference tape speed output from
And an error calculation section 32 that calculates an error signal for driving the reel motor 1 based on the output of the subtraction section 31. The tape speed control unit 3 controls the magnetic tape to be wound by the T reel at a predetermined speed (details will be described later).

FIG. 2 shows the basic operation of the tape running speed control device shown in FIG. First, when the reel motor 1 is started from the stopped state, the reel motor FG control unit 2 controls the reel motor 1 to rotate at a predetermined rotation cycle. This rotation cycle is a value which becomes 40 times faster when the winding diameter of the S reel is almost zero. The range described as "low speed" in FIG. 2 shows this rotation cycle control. That is, the tape speed in this range is not strictly constant, and the tape speed increases as the winding diameter of the S reel decreases.

After a lapse of a certain time, acceleration is then started toward 200x speed, and when 200x speed is reached, control is performed so that the speed becomes constant. This speed control is performed using the output of the tape speed control unit 3. However, it does not accelerate when the T reel is already wound near the tape end. Whether it is close to the tape end is determined by detecting the winding diameter of the S reel or the T reel (details will be described later).

When the tape is wound up near the tape end and controlled at 200 times speed, deceleration is started so that the speed becomes as low as 40 times speed. When the speed reaches about 40 times, the reel motor FG is controlled so that the rotation cycle becomes constant. This rotation cycle is a value which becomes 40 times faster when the winding diameter of the S reel is almost zero. At this time, the speed control during deceleration is performed using the output of the tape speed control unit 3, and the rotation cycle control of about 40 times speed is performed using the output of the reel motor FG control unit 2.

Finally, when the tape end is detected, the running of the magnetic tape is stopped. Here, instead of starting up at 40 times speed from startup, it may be started up at 10 times, 20 times, 40 times. The same applies to the low speed before the stop. The operation of REW has been described above, but the same applies to the case of FF. However, in the case of FF, the top of the tape is detected and stopped.

Returning to FIG. 1, description will be made. The tape speed detection unit 4 includes a tape length detection unit 41 that detects the reference value of the tape length by using the output of the cycle measurement unit 6S and the cycle measurement unit 6T at the time of 1 × speed, a cycle measurement unit 6S, and a cycle measurement unit 6T. Present (= n
Tape speed detecting unit 42 for detecting the current tape length using the output of (double speed), and tape speed for calculating the current tape speed using the output of the tape length detecting unit 41 and the output of the tape length detecting unit 42. And a calculation unit 43.

The principle of tape speed detection will be described with reference to FIG. In this figure, 7S is a magnetic tape wound on an S reel, 7T is a magnetic tape wound on a T reel, 8S is an S reel shaft, 8T is a T reel shaft, and Rs is an S reel winding diameter. Rt is the winding diameter of the T reel, and Rh is the shaft diameter of the S reel and the T reel.

In FIG. 3, when the total length of the magnetic tape is L and the thickness of the tape is μ, π (Rs ² −Rh ² ) + π (Rt ² −Rh ² ) = Lμ ...

When both sides of the equation are multiplied by π and transposed, π (Lμ + 2πRh ² ) = π ² (Rs ² + Rt ² ) ...

The value of the equation is the axis 8S, the magnetic tape 7S, the axis 8
T is the sum of the areas of the magnetic tape 7T and is a constant value depending on the tape cassette.

Assuming that the rotation cycle of the S reel is Ts, the rotation cycle of the T reel is Tt, and the tape speed is V, then V = 2π (1 / Ts) Rs = 2π (1 / Tt) Rt.

When Rs and Rt are obtained from the equations and substituted into the right side of the equations, V ² (Ts ² + Tt ² ) = K (= constant) ...

Therefore, assuming that the tape speeds at 1 × speed and n × speed, the S reel base cycle, and the T reel base cycle are V1, Vn, Rs1, Rsn, Rt1, and Rtn, respectively, V1 (Ts1 ² + Tt1 ² ) ^{1 / 2} = Vn (Tsn ² + Ttn ² ) ^1/2 = K ^1/2

From the equation, Vn / V1 = (Ts1 ² + Tt1 ² ) ^1/2 / (Tsn ² + Ttn ² ) ^1/2 = X1 / Xn.

Therefore, when the square root X1 (= reference tape length) of the sum of squares of the rotation period of the reel stand at the time of 1 × speed is set,
The tape speed can be detected from the ratio between this and the square root Xn of the sum of squares of the rotation period of the reel stage at the n-fold speed.

Returning to FIG. 1, description will be made. The control reference value generation unit 5 includes a winding diameter detection unit 51 that detects the winding diameter Rs of the S reel from the output of the period measurement unit 6S, the output of the period measurement unit 6T, and the output of the tape speed calculation unit 43. Diameter detector 5
A mode selection for selecting a mode using the output of the reel motor FG control unit 2 (hereinafter referred to as reel motor FG control mode) or a mode using the output of the tape speed control unit 3 (hereinafter referred to as tape speed control mode) based on the output of 1 In the reel motor control unit 2, the unit 52, the target speed generation unit 53 that generates a target speed according to the mode of the mode selection unit 52, and the final target speed set at the time of start-up, and the output of the target speed generation unit. A frequency division ratio generation unit 54 that generates the frequency division ratio of the frequency division unit 21 and a reference value generation unit 55 that generates the reference period of the reel motor FG using the output of the target speed generation unit.

Next, the operation of the tape traveling speed control device shown in FIG. 1 will be described. First, when the FF or REW mode is set by the user's operation while the magnetic tape is stopped, the apparatus of FIG. 1 is started. At the time of startup, 200 times the final target speed is set and the reel motor FG control mode is set. At this time, the target speed generator 53 generates a target speed corresponding to 40 times speed. Further, the frequency division ratio generation unit 54 sets the frequency division ratio of the frequency divider 21 to “4”.
Set to. Then, the reference value generation unit 55 generates a target rotation cycle that makes the speed 10 times faster when the winding diameter of the S reel is almost zero, and supplies the target rotation cycle to the subtraction unit 23. As a result, the reel motor 1 rotates at a rotation cycle of 40 times speed when the S reel has a winding diameter with almost no remaining amount.

While running in the reel motor FG control mode described above for a while, the tape speed detecting section 4 calculates the tape speed using the above-mentioned formula. Further, the winding diameter detecting unit 51 in the control reference value generating unit 5 calculates the winding diameter Rs of the S reel by using the above-described formula. And
If the winding diameter Rs is a predetermined value or more, acceleration is started. In addition,
The square root X1 of the sum of squares of the rotation cycle of the reel stage at 1 × speed is measured in advance and stored in the memory in the microcomputer.

When acceleration is started, the mode selection unit 52 selects the tape speed control mode. Then, the target speed generation section 53 gives the subtraction section 31 of the tape speed control section 3 a gradually increasing reference tape speed such as 40 → 41 → 42 →. Since the final target speed is set to 200 at startup, the reference tape speed becomes constant when it reaches 200.

The winding diameter detecting section 51 always detects the winding diameter. Then, when this value becomes equal to or less than the predetermined value, deceleration is started, and the tape speed control unit 3 decelerates as it is. At this time, the target speed generator 53 instructs the subtractor 31 of the tape speed controller 3 to enter 200 → 199 → 19.
It gives a gradually decreasing reference tape speed such as 8 → ... Then, when this value reaches 40, the mode selection unit 52 selects the reel motor FG control mode.
Then, by the control of the reel motor FG controller 2,
When the tape end is detected by the low speed control of about 0x speed, the running of the magnetic tape is stopped.

The processing of the tape speed control unit 3 in FIG. 1 is shown in FIG. Here, the "detected tape speed" is
The tape speed given by the tape speed detection unit 4,
The “target tape speed” is the tape speed given by the control reference value generation unit 5. First, the "target tape speed" is subtracted from the "detected tape speed" to detect the speed error.
This is the process of the subtraction unit 31. The subsequent process is the process of the error calculation unit 32. First, the speed error is limited, then the proportional error, the derivative error, and the integral error are calculated, and the integral value is limited. Then, the error values are summed, the result is limited, and converted into a PWM value and output.

FIG. 5 is a block diagram when the processing of FIG. 4 is configured by hardware. In this figure, "D" is a delay circuit for one sample.

Reel motor FG control unit 2 in FIG.
The process of is shown in FIG. In this figure, the “calculation of period” is measured by the period measuring unit 22 counting the intervals of the output of the frequency dividing unit 21. The “target FG cycle” is the reference FG cycle generated by the reference value generation unit 55. First,
The target tape speed is subtracted from the cycle measured by the cycle measuring unit 22 to detect the cycle error. This is the process of the subtraction unit 23. The subsequent process is the process of the error calculation unit 24.
First, a limiter is applied to the cyclic error, then a proportional error and an integral error are calculated, and a limiter is applied to the integrated value. Then, the error values are summed, the results are limited, and the errors are averaged, converted into a PWM value, and output. The reason why the errors are averaged here is to eliminate the variation in the measured period.

Although the magnetic tape is run at high speed by driving the reel motor in the above-mentioned embodiment, the present invention can be applied to the case where the magnetic tape is run at high speed by driving the capstan motor. You can In that case, a capstan motor may be used instead of the reel motor 1 of FIG. 1, and a capstan motor FG control unit may be provided instead of the reel motor FG control unit 2. Further, although the above embodiment relates to the digital VTR, the present invention can be applied to DAT.

[0040]

As described in detail above, according to the present invention, speed control of a magnetic tape from low speed to high speed can be easily performed. In addition, stable low speed running can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a tape traveling speed control device to which the present invention is applied.

FIG. 2 is a diagram showing a basic operation of a tape traveling speed control device to which the present invention is applied.

FIG. 3 is a diagram illustrating the principle of tape speed detection.

FIG. 4 is a flowchart showing processing of a tape speed control unit.

FIG. 5 is a block diagram when an error calculation unit of a tape speed control unit is realized by hardware.

FIG. 6 is a flow chart showing processing of a reel motor control unit and a block diagram when the error calculation unit is realized by hardware.

[Explanation of symbols]

1 ... Reel motor, 2 ... Reel motor FG control unit,
3 ... Tape speed control unit, 4 ... Tape speed detection unit, 5
... Control reference value generator

Claims (5)

[Claims] 1. A device for controlling a running speed of the magnetic tape in a device for reproducing data recorded on an oblique track of the magnetic tape, comprising a motor for running the magnetic tape, and a running speed of the magnetic tape. Means for detecting the number of rotations of the motor, and means for generating a reference signal for controlling the motor, the means for generating the reference signal, the running speed of the magnetic tape A tape running speed control device having a first mode for keeping constant and a second mode for keeping the number of rotations of the motor constant. 2. The tape running speed control device according to claim 1, wherein the motor for running the magnetic tape is a reel motor. 3. The tape running speed control device according to claim 1, wherein the means for detecting the running speed of the magnetic tape is based on the rotation cycle of the reel stand. 4. The means for generating a reference signal is in a second mode when the running speed of the magnetic tape is below a predetermined value,
When the traveling speed of the magnetic tape exceeds a predetermined value, the first
The tape running speed control device according to claim 1, wherein the tape running speed control device is set to the mode. 5. A method for controlling a running speed of the magnetic tape in an apparatus for reproducing data recorded on an oblique track of the magnetic tape, wherein the magnetic tape is set to a predetermined value when the running speed of the magnetic tape is equal to or less than a predetermined value. A tape is characterized in that the number of revolutions of a motor for traveling the tape is controlled to be constant, and when the traveling speed of the magnetic tape exceeds a predetermined value, the traveling speed of the magnetic tape is controlled to be constant. Driving speed control method.