JP2000048430A - Magnetic tape unit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When a tape is running, a soft timer in a control unit checks an interrupt interval, and when a current is continuously supplied to a reel motor, the tape is not interrupted for a certain time. To prevent tape runaway. SOLUTION: Two reel motors 21 and 22 for feeding and winding the tape, a control unit 1a for controlling the two reel motors 21 and 22, and two reel motors 21 and 2 are provided.
The control unit 1a includes rotation pulse generating means 42a and 92a for generating a pulse for detecting the rotation speed of each of the two axes, and a soft timer 100 determined by a time for performing a specified process in the control unit. The rotation pulse generating means 4 is provided within the predetermined time of the soft timer 100.
When the pulses from 2a and 92a are not detected, the two reel motors 21 and 22 are stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape device for performing recording and reproduction using a cartridge tape as a recording medium. In particular, the present invention relates to a magnetic tape device that performs drive control using a digital signal processor (hereinafter, referred to as "DSP") when performing PWM (pulse width modulation) control of a reel motor or the like for running a magnetic tape. About.

[0002]

2. Description of the Related Art A conventional magnetic tape device will be described below. FIG. 11 is an explanatory view of a conventional example, FIG. 11A is a block diagram of a servo control system, and FIG. 11B is an internal circuit of a PWM control unit.

Conventionally, a magnetic tape device using a cartridge tape (for example, a "3590" cartridge tape) as a recording medium has been known. In such a magnetic tape device, the reel motor drives the take-up reel and the supply (feed) reel to drive the magnetic tape to travel.

As shown in FIG. 11A, a servo control system for driving and controlling the reel motor (hereinafter, also simply referred to as “motor”) includes a DSP 1 for controlling the entire servo control system, A digital / analog converter (hereinafter referred to as "DAC") 2 for converting a digital signal of an indicated value set by the DSP 1 into an analog signal;
A PWM control unit 3 for generating a PWM (pulse width modulation) pulse based on the indicated value converted by the DAC 2;
A power amplifier unit 4 that drives the motor 5 by controlling the driving of the driving element by the PWM pulse output from the control unit 3 is provided. The motor 5 is provided with a tachometer 42 having 500 slits on the tape supply reel side, and one photosensor (index) on one turn on the take-up reel side.

In this case, the current flowing through the motor 5 (reel motor current) is detected via the power amplifier unit 4 and the detected current value (actually measured current value) is fed back to the PWM control unit 3. Then, the PWM control unit 3 performs PWM based on the current detection value and a current instruction value from the DSP 1.
A pulse is generated and supplied to the power amplifier unit 4. The PWM controller 3 and the power amplifier 4 constitute an analog constant current servo amplifier.

A PWM for generating a PWM pulse as described above
The M control unit 3 is provided with an analog circuit as shown in FIG. 11B, and generates a PWM pulse by this analog circuit. That is, in the PWM control unit 3,
Summing amplifier (AMP) 61 and sawtooth wave generating circuit 63
And an analog circuit composed of a comparator (comparator: CMP) 62.

The summing amplifier 61 inputs the current instruction value sent from the DSP 1 and the current detection value of the motor 5 detected via the power amplifier section 4 and adds them, thereby indicating a current error between the two. The comparator 6 generates an error voltage.
Output to 2. The sawtooth wave generation circuit 63 generates a sawtooth wave signal (sawtooth signal) having a constant period in accordance with the ON timing of the PWM pulse, and outputs the signal to the comparator 62.

The comparator 62 receives and compares the error voltage of the summing amplifier 61 and the sawtooth wave signal output from the sawtooth wave generating circuit 63, and turns off the PWM pulse when the two match. Signal to low level L). Thus, the on / off of the PWM pulse is controlled, and the PWM pulse is output.

In a conventional magnetic tape device, the reel tape drives the reel on the winding side and the reel on the supply side to drive the magnetic tape to travel. In the conventional magnetic tape device, the DSP is interrupted at the rising edge of the precise tach pulse of 500 slits, and the reel rotation speed is determined by measuring the interrupt interval with a counter.

[0010] Further, the tape running reel motor of the magnetic tape device using the conventional cartridge tape has a precision tachometer with 500 slits on the tape supply reel side.
A single photo diode-type photosensor was mounted on the take-up reel side.

Further, the tape speed of a conventional magnetic tape device is detected only by a tachometer of a reel motor.

[0012]

The above-mentioned prior art has the following problems. (1): At the rising edge of the precision tach pulse of 500 slits, the DSP was interrupted and the rotation speed of the reel was determined by measuring the interruption interval with a counter, resulting in a hardware error such as no tach pulse output. In this case, the DSP was not interrupted, the rotational speed could not be recognized, and it was erroneously recognized as stopped, and the reel motor was continuously supplied with current, causing tape runaway.

(2): A tape running reel motor of a magnetic tape device using a cartridge tape has a precision tachometer with 500 slits on the tape supply reel side and a one-shot diode-type photo on the winding reel side. Since the sensor was mounted, the fluctuation could not be detected before the tape slip or the tension alarm was detected on the tape path, unless the interval of the precision tachometer of the 500 slit on the supply reel side fluctuated greatly.

(3): The tape speed of the tape device is
There was no alternative for speed detection, since detection was performed only by the tachometer of the reel motor. The present invention has a function of checking the interrupt interval even by a soft timer inside the DSP during tape running, and stopping the tape if the DSP is not interrupted for a certain period of time even though the current continues to flow to the reel motor. It is an object of the present invention to provide a magnetic tape device having:

Another object of the present invention is to provide a magnetic tape device having a function of calculating an accurate rotation speed, a tape winding diameter, and the like by measuring a precision tacho pulse and a pulse interval of an encoder with a precision clock. I do.

Further, according to the present invention, when the tape runs out of control, the reel motor continues to rotate at a high speed with almost no load, so that the on-time of the PWM pulse cycle becomes longer and the on-time remains limited. It is another object of the present invention to provide a magnetic tape device having a function of stopping a tape when the limit state continues for several tens of cycles during tape constant speed running control.

[0017]

FIG. 1 is a diagram illustrating the principle of the present invention. In FIG. 1, 1a is a control unit, 21 and 22 are reel motors, 41a and 91a are index pulse generators, 42a and 92a are rotation pulse generators, and 100 is a soft timer.

The present invention is configured as follows in order to solve the above-mentioned conventional problems. (1): Two reel motors 21 and 22 for feeding and winding the tape, a control unit 1a for controlling the two reel motors 21 and 22, and the two reel motors 2
Rotation pulse generating means 42a and 92a for generating a pulse for detecting the rotation speed of each of the first and second axes, and a soft timer 1 determined by the time for performing the prescribed processing in the control unit
The control unit 1a is configured to, when a pulse from the rotation pulse generating means 42a, 92a is not detected within a predetermined time of the soft timer 100 during the constant speed running of the tape, the control unit 1a The reel motors 21 and 22 are stopped.

(2) Two reel motors 21 and 22 for feeding / rewinding the tape, a controller 1a for controlling the two reel motors 21 and 22, and two reel motors 21 and 22 The control unit 1a includes rotation pulse generation means 42a and 92a for generating pulses for detecting the respective rotation speeds. The control unit 1a determines whether or not a pulse from the rotation pulse generation means 42a of one of the reel motors has been detected. When the pulse from the rotation pulse generating means 92a of the other reel motor is not detected, the two reel motors 21 and 22 are stopped.

(3): Two reel motors 21 and 22 for feeding / rewinding the tape, a controller 1a for controlling the two reel motors 21 and 22, and a control unit for the two reel motors 21 and 22. Rotation pulse generating means 42a, 9 for generating pulses for detecting the respective rotation directions and speeds
2a and index pulse generating means 41a and 91a for generating an index pulse by rotation of the reel motors 21 and 22. The control unit 1a is capable of moving the tape in the same direction. When the number of pulses of the rotation pulse generating means 42a, 92a is smaller than a specified value, or when a pulse of reverse rotation is detected from the rotation pulse generating means 42a, 92a, at the interval of generation of the index pulse, the two reel motors 21, 2
Stop 2

(4) Two reel motors 21 and 22 for feeding / rewinding the tape, sensors for detecting the positions of the rotating magnetic poles of the two reel motors 21 and 22, and the reel motors 21 and 22. Encoder pulse generating means for generating an encoder pulse from the output of the sensor by the rotation of the sensor, and the two reel motors 21 and 22
Control unit 1a for controlling the two reel motors 2
The control unit 1a includes rotation pulse generation units 42a and 92a that generate pulses for detecting the rotation speeds of the first and second axes. The control unit 1a outputs pulses from the encoder pulse generation unit of one of the reel motors 21. Nevertheless, when no pulse is output from the encoder pulse generating means of the other reel motor 22, or the number of pulses of the rotation pulse generating means 42a, 92a in one cycle of the encoder pulse generating means is equal to the expected value. If the numbers differ, the two reel motors 21 and 22 are stopped.

(5): Two reel motors 21 and 22 for feeding and winding the tape, a controller 1a for controlling the two reel motors 21 and 22 by PWM pulses, and the two reel motors 21 and 22. Rotation pulse generating means 42 for generating a pulse for detecting the rotation speed of each shaft
a, 92a, and the controller 1a stops the two reel motors 21 and 22 when the on-time close to the PWM pulse limit state continues for a specified cycle during the tape constant-speed running control. .

(Operation) The operation based on the above configuration will be described. Two reel motors 2 for tape feeding / winding
When a pulse from the rotation pulse generating means 42a, 92a is not detected within 100 hours of a predetermined soft timer while the tape is running at a constant speed, the control unit 1a controls the two reel motors. 21 and 22 are stopped.
Therefore, even when a pulse from the rotation pulse generating means 42a, 92a cannot be detected due to a hardware abnormality or the like, the abnormality can be checked by the soft timer 100 and tape runaway can be prevented.

The control unit 1a for controlling the two reel motors 21 and 22 for feeding / rewinding the tape may detect a pulse from the rotation pulse generating means 42a of one of the reel motors 21. If no pulse from the rotation pulse generating means 92a of the other reel motor 22 is detected, the two reel motors 21, 2
Stop 2 Therefore, it is possible to protect the tape from running away due to an abnormality of the rotation pulse generating means or the like, and protect the tape from being cut.

Further, a control unit 1a for controlling two reel motors 21 and 22 for feeding and winding the tape is provided.
Although the tape is running in the same direction, the rotation pulse generating means 4
2a, when the pulse of 92a is less than the specified value, or
When a reverse rotation pulse is detected from the rotation pulse generating means 42a, 92a, the two reel motors 21, 22 are stopped. For this reason, it is possible to protect the tape from running out of control due to the abnormality of the rotation pulse generating means or the reverse rotation of the reel, and the tape cutting.

In the control unit 1a for controlling the two reel motors 21 and 22 for feeding and winding the tape, the pulse is output from the encoder pulse generating means of one of the reel motors 21. If no pulse is output from the encoder pulse generating means of the other reel motor 22, or if the number of pulses of the rotation pulse generating means 42a, 92a for one cycle of the encoder pulse generating means differs from the expected value by a specified number, The two reel motors 21 and 22 are stopped. For this reason, the rotation of the reel motor can be checked by the rotation pulse generators 42a and 92a and the encoder pulse generator, and tape runaway and tape cutting protection can be performed.

Further, a control unit 1a for controlling the two reel motors 21 and 22 for feeding / rewinding the tape by a PWM pulse, and during a tape constant speed running control, an on-time close to a limit state of the PWM pulse for a specified cycle. , The two reel motors 21 and 22 are stopped. Therefore, it is possible to prevent a tape runaway in which a limit state in which the on-duty of the PWM pulse exceeds 90% continues during the tape constant-speed running control.

[0028]

2 to 9 show an embodiment of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the drawings. (1): Description of the magnetic tape device FIG. 2 is an explanatory diagram of the magnetic tape device. As shown in FIG. 2, the magnetic tape device is provided with a mechanism including a motor (machine motor) 21 for driving a machine reel, a motor (file motor) 22 for driving a file reel, and a head 23. The recording / reproducing of data to / from the magnetic tape is performed by using the mechanism (1).

When a cartridge tape (a magnetic tape containing a cartridge) is inserted into the magnetic tape device, the cartridge tape is automatically set at a predetermined position.
Then, the leader block provided at the leading end of the magnetic tape is pulled out of the cartridge tape by the internal mechanism, and is conveyed to the position of the machine reel. Then, the leader block is mounted on the machine reel.

In this state, the magnetic tape follows the locus 24 of the magnetic tape and is wound up from a file reel to a machine reel. Next, when rewinding the magnetic tape, the rotation of the reel motor follows a trajectory opposite to that described above, and the magnetic tape wound around the machine reel is rewound to the file reel side. Finally, the leader block is inserted into the cartridge, and the winding is completed.

The traveling drive of the magnetic tape is performed as described above. However, the rotation direction of the reel motor is reversed between when the magnetic tape is wound and when the magnetic tape is rewound. This control is performed based on an instruction from a higher-level control unit.

(2) Description of Magnetic Tape Control Unit FIG. 3 is an explanatory diagram (part 1) of the magnetic tape control unit, and FIG. 4 is an explanatory diagram (part 2) of the magnetic tape control unit.

In FIG. 3, a DSP 1 and an index counter 1 are connected to a data bus 10 connected to a higher-level control unit.
2. The tach counter 13, the tach timer 14, the encoder counter 16, the encoder timer 17, and the on-time precise clock (E) from the PWM circuit 30 are connected. D
SP1 is provided with an internal soft timer 100, to which an oscillator 18, an interrupt circuit 19, and a data bus 20 are connected. The index counter 12, the tach counter 13, and the tach timer 14 are connected to a receiving circuit (file / machine index / tachometer) 11. Encoder counter 16, encoder timer 17
Is a receiving circuit (file and machine, encoder) 15
Is connected to The output of the index 41, the tachometer 42, the index 91, and the tachometer 92 is input to the receiving circuit 11. In the receiving circuit 15,
Outputs of the encoder 43 and the encoder 93 are input. The outputs of the encoder 43 and the encoder 93 are input to the interrupt circuit 19.

In FIG. 4, the data bus 20 has a DS
EPROM for P (erasable programmable read only)
memory) 26, a write register 27 for turning on / off the switch SW, an SRAM (static r) for DSP calculation processing.
and an access memory 28, a file DAC (digital / analog converter) 2, and a machine DAC 7.

The output of the file DAC 2 is given to the PWM control unit 3, and the output of the PWM control unit 3 is given to the file motor 22. The file motor 22 drives a file reel 34. Further, the rotation of the file motor 22 is calculated by using an index 41, a tachometer 42, and an encoder 43.
Detected by. The output of the index 41 is given to the receiving circuit 11, the output of the tachometer 42 is given to the receiving circuit 11 and the interrupt circuit 19,
Is supplied to the receiving circuit 15. Further, the file motor 22 has a drive circuit, and the file motor 22
Is detected by terminals C and D at both ends of the resistor R _S1 and terminals A and B at both ends of the resistor R _S2 , and are fed back to the PWM control unit 3.

The output of the machine DAC 7 is output from the PWM controller 3
Is provided to the PWM control unit 8 having the same configuration as
The output of the control unit 8 is provided to the machine motor 21. The machine motor 21 drives a machine reel 35. Also,
The rotation of the machine motor 21 is detected by an index 91, a tachometer 92, and an encoder 93. The output of the index 91 is provided to the receiving circuit 11, the output of the tachometer 92 is provided to the receiving circuit 11 and the interrupt circuit 19, and the output of the encoder 93 is provided to the receiving circuit 15. Further, the machine motor 21 has a drive circuit like the file motor 22, detects a current for driving the machine motor 21, and feeds it back to the PWM control unit 8.

A) Description of PWM Control Unit The PWM control unit 3 includes a PWM circuit 30 and an addition amplifier 3
1, an amplifier 32, an amplifier 33, and a switch SW are provided. The PWM circuit 30 generates a PWM (pulse width modulation) pulse based on the instruction value from the addition amplifier 31. The summing amplifier 31 includes a file DAC 2 and a switch S
The output of W and the output of the amplifier 33 are added. The amplifier 32 amplifies the outputs of the terminals C and D. The amplifier 33 amplifies the outputs of the terminals A and B. The switch SW is controlled to open and close by the value of the write register 27, and when the file motor 22
It is closed when the WM signal (pulse) is off, and is open when the PWM signal in the drive mode and in the regenerative mode is on.

B) Description of PWM circuit FIG. 5 is an explanatory diagram of the PWM circuit. In FIG. 5, PW
The M circuit 30 includes a comparator 51, an AND circuit 52,
Flip-flop circuits (FF) 53, a driver 54, the transistor T _r for switching, resistors R _11, R _12, Zener diode ZD, a capacitor C is provided. Incidentally, + 12V power supply voltage, I _c is the current flowing through the capacitor C, V _Z is Zener voltage of the Zener diode ZD, V _BE
The base-emitter voltage of the transistor T _r, V _c indicates the terminal voltage of the capacitor C (output voltage).

The operation of the PWM circuit 30 is as follows. A periodic pulse of PWM from DSP1 or the like (4 in this example)
0 μs) is applied to the terminal * PR of the FF 53, the driver 54 is driven by the output of the terminal * Q, and the voltage of the capacitor C is discharged. Thereafter, a current flows through a path of +12 V → ZD → resistance R ₁₁ → GND by a power supply voltage of +12 V, and a constant Zener voltage V _Z is generated. Since the predetermined voltage V _BE is applied between the base and emitter of the transistor T _r The Zener voltage _{V Z, + 12V → R 12} → T r
Current flows through the path of the emitter-collector → C → GND, and the capacitor C is charged according to a predetermined time constant.

The charging voltage of the capacitor C is the next 40 μs.
It is discharged by a PWM periodic pulse applied to the terminal * PR. After that, the capacitor C is charged again,
The above operation is repeated.

[0041] By this operation, the sawtooth wave signal is obtained as a change in the terminal voltage V _c of the capacitor C. In this case, the charging current I _c of the capacitor C, the terminal voltage V _c of the capacitor C is represented by the following formula.

That is, I _c = (V _Z -V _BE ) / R ₁₂ ,
By Q = CV _c,

[0043]

(Equation 1)

[0044] Thus the terminal voltage V _c of the capacitor C has been integrated over time, becomes sawtooth wave. The sawtooth signal is supplied to a summing amplifier 31 by a comparator 51.
When the sawtooth signal is lower than the output of the addition amplifier 31, “high” is output from the comparator 51, applied to the terminal D of the FF 53, and a PWM on pulse is output from the terminal Q. The sawtooth signal is added to the summing amplifier 31.
, The comparator 51 outputs “low” and is supplied to the terminal D of the FF 53, and the terminal Q outputs a PWM off pulse.

The AND circuit 52 receives a 12 MHz clock and a PWM pulse from the oscillator 18 and the like. Therefore, the AND circuit 52 outputs a 12 MHz clock during the period of the PWM on-pulse (E). The PWM ON period is calculated by counting this clock with the DSP 1 or the like.

C) Description of motor drive unit FIG. 6 is an explanatory diagram of a switching constant current amplifier.
A illustrates the drive mode, and FIG. 6B illustrates the regenerative mode. The said switching constant current amplifier, and four transistors of the transistor T _r1 through T _r4, diodes D ₁ ~
D ₄ , d ₁ and d ₂ are provided, and the motor M is driven by these elements.

The switching constant current amplifier is supplied with a power supply voltage + V for driving, and also detects resistors R _S1 and R _S2 (sense resistors) in order to detect a current (motor current) flowing through the motor M. Is provided. The motor current is detected as a voltage value proportional to the motor current by the resistors R _S1 and R _S2 , and is fed back by the addition amplifier 31 through the resistor R ₃ .

The operation of the switching constant current amplifier is as follows. The switching constant current amplifier forms a constant current in two modes: the drive mode in FIG. 6A and the regenerative mode in FIG. 6B.

That is, the output of the file DAC and the machine DAC, which are the control current instruction values of the tape supply reel (file reel) and the take-up reel (machine reel), is connected in series to the windings of a three-phase brushless motor. The current flowing through the resistors R _S1 and R _S2 is detected and fed back by the addition amplifier 31 through the resistor R ₃ (see FIG. 4).

The operation state of each mode is shown in the lower part of FIG.
It is. Shown is the transistor T _r1Applied to the base of
Voltage is the transistor T_r4Applied to the base of the
The pressure indicates a current flowing through the motor M (motor current).

Description of Driving Mode In FIG. 6A, in the driving mode, the transistor T_r4To
With the sensor output (Hall element output) turned on,
Lanista T_r1On / off by PWM pulse
And the motor current I becomes a substantially constant high value as shown in FIG.
At this time, the transistor T_r1Is turned on, the solid line
As shown, + V → T_r1→ Motor M → T _r4→ d_Two→ R
_S2→ The current I of the motor M flows through the GND path.

[0052] In addition, when the transistor T _r1 is turned off,
As shown by a broken line in the drawing, the voltage induced in the motor M, D3 → motor _{M → T r4 → d 2 →} R S2 → GND path current I flows. At this time, the current I is converted into a voltage value from the terminals A and B of the resistor R _S1 and detected, and is fed back to the PWM control unit 3 as a current detection value. In this case, the transistors _Tr2 and _Tr3 remain off.

[0053] - In the illustration 6B regenerative mode, the tape supply side reel motor driven in regenerative mode, by simultaneously supplying the PWM pulses to the base of transistor T _r1, T _r4, transistor T _r1, T _r4 At the same time. Then, when the transistor T _r1, T _r4 is off, by a flow a regenerative current that occurs to the diode D _3, D ₂ from the induced voltage of the motor M, reduces the motor torque. This enables back tension control of the tape supply side reel motor of the magnetic tape device.

On the other hand, the drive of the reel motor on the tape winding side is performed in the drive mode shown in FIG. 6A. In this driving mode, the transistor T _r1 is turned on / off driven by the PWM pulse, the transistor T _r4, the motor M
It is turned on / off based on an output signal from a sensor (Hall element) that detects the rotation of the motor.

[0055] In a regenerative braking mode shown in Figure 6B, when the transistor T _r1 and T _r4 are turned on simultaneously, as it is shown in the illustrated solid line, + V → T _r1 → motor M → T _r4 → d2 → R
The drive current I of the motor M flows through the path of _S2 → GND. At this time, the current I is converted into a voltage value from the terminals A and B of the resistor R _S2 and detected, and the PWM control unit 3
Is fed back to

[0056] Further, when the transistor T _r1 and T _r4 is off, the voltage induced in the motor M, as indicated by a broken line in the _{drawing, GND → R S1 → D 3} → motor M → D ₂ → + V
The regenerative current I (current returned to the power supply) flows through the path.
At this time, the current is detected from the terminals C and D of the resistor R _S1 and is fed back to the PWM control unit 3 as a current detection value. In this case, the transistors _Tr2 and _Tr3 remain off. The transistors in this amplifier section are not limited to bipolar transistors, but may be MOS-type FETs or the like.
It can be realized by other similar transistors.

(3) Description of Drive Sequence of Brushless Motor FIG. 7 is an explanatory diagram of the drive sequence of the brushless motor. FIG. 7 shows, from the top, waveforms of the mechanical angle, the outputs P1, P2, and P3 of the pole sensors, the encoder pulse outputs, the winding currents of the coils rotating clockwise, and the winding currents of the coils counterclockwise.

In the brushless motor, outputs P1, P2, and P3 of three pole sensors constituted by Hall elements and the like for detecting the magnetic pole position are shifted by a mechanical angle of 12 °. When the brushless motor rotates, outputs P1, P2, and P3 shifted by 12 ° are obtained. The encoder pulse output becomes “high” when two of the outputs P1, P2, and P3 of the pole sensor are “high”.

When the coil driving current is rotated clockwise,
For example, the coil A is driven in the order of (1) to (6). That is, in the case of the mechanical angle of 0 ° to 12 ° (1), the motor is driven by a negative current, and in the case of the mechanical angle of 12 ° to 24 ° (2), the driving current is zero, and in the case of the mechanical angle of 24 ° to 48 ° (3). , (4) are driven by a positive current and have a mechanical angle of 48 ° to 60 ° (5).
, The driving current becomes zero, and the motor is driven by a negative current in (6) of the mechanical angle of 60 ° to 72 °.

(4): Description of the connection state of the brushless motor FIG. 8 is an explanatory diagram of the connection of the brushless motor and the tachometer, and FIG. 8A is a description of the connection state of the brushless motor. In FIG. 8A, the brushless motor is provided with coils A, B, C, and pole sensors PS1, PS2, PS3. Drive currents IA, IB, and IC of each coil are supplied from one terminal of each of the coils A, B, and C, and the other terminals are connected to each other. The drive current to each of the coils A, B, and C is driven in the order of (1) to (6) in the case of clockwise rotation as in the drive sequence of FIG. 7 and in the order of to in the case of counterclockwise rotation. Driven.

The pole sensors PS1, PS2, PS3 output respective outputs P1, P2, P3. (5): Description of rotation speed and tape winding diameter FIG. 8B is a description of a tachometer. In FIG. 8B, a slit i for generating one index pulse per rotation is formed on a rotating disk p directly connected to the reel motor shaft.
And a slit t for generating a precision tach pulse of 1024 pulses is provided in one round. The pulse is generated, for example, by detecting light passing through the slit with a phototransistor or the like.

In a magnetic tape device using a brushless motor for rotating both (file and machine) reels, a counter value for counting 1024 slits out of the number of tachometer pulses (tach pulses) of a tachometer directly connected to both reel motor shafts. And a counter value for counting encoder pulses (Hall element output pulses) of both reels.

Therefore, the rotation speed and the tape winding diameter can be accurately calculated by measuring the pulse interval of the 1024 slit precision tach pulse and the encoder pulse with the precision clock.

[0064] When the tape winding diameter of the file reel and the take-up reel is the same, tachometer pulses R _F of the tachometer pulse R _M and the file reel side of the machine reel side between the index pulse of one of the reel comes out one shot is the same (R _M = R _F
= 1024).

The file reel is a machine reel tape winding.
If the diameter is larger than the diameter of one (file) reel
Tacho pal on the machine reel side during one pulse
R _MIs the tacho pulse R on the file reel side_FLess
Become (R_M<R_FR_MIs less than 1024). This
For the tape running speed and tacho pulse R_MAnd R_Fcomparison
, The tape winding diameter can be calculated.

(6): Description of Tape Runaway Prevention Conventionally, at the rising edge of a precision tach pulse of 500 slits, the DSP is interrupted, and the interval between interruptions is measured by a counter to determine the rotation speed of the reel. However, when a hardware error such as no tach pulse output occurs, the DSP is not interrupted, the rotational speed cannot be recognized, and the reel motor is erroneously recognized as stopped and continues to flow current to the reel motor. This caused tape runaway.

A) Description of Check by Soft Timer When the tape is running at a constant speed, the interrupt interval is also checked by the soft timer (see reference numeral 100 in FIG. 3) inside the DSP, and the current is continuously supplied to the reel motor. Nevertheless, a function to stop the tape when the DSP is not interrupted for a certain time is provided.

FIG. 9 is a flow chart of the tape constant speed running process. Hereinafter, description will be made in accordance with the processes S1 to S7 of FIG. S1: When the DSP 1 receives the “Forward Read Command start” which is a general command of the constant speed running, the DSP 1 accelerates the tape feed (FWD), and proceeds to the processing S2.

S2: The DSP 1 determines whether the tape speed has reached 75% or more of the target. If it is determined that the value exceeds 75% of the target, the process proceeds to step S3.
If not, the process returns to step S1.

S3: The DSP 1 performs a constant speed running process of the tape feed, and proceeds to the process S4. S4: The DSP 1 determines whether the interrupt time interval due to the rise of the tacho pulse is within twice the expected value. In this determination, if the interrupt time interval is within twice the expected value, the process proceeds to step S5, and if not, the tape stop process is performed.

S5: The DSP 1 determines whether the value of the soft timer is at least 75% of the tape speed. If it is determined that the speed is 75% or more of the tape speed, the process proceeds to step S6. If the speed is not 75% or more, the tape stop process is performed.
Note that the soft timer counts how many times the process S3 to the process S6 are looped (also referred to as a loop counter). For example, the tape speed is determined based on whether or not an interruption of a tacho pulse occurs when the loop is performed ten times.

S6: The DSP 1 determines whether a stop command has been issued. If it is determined that a stop command has been issued, the process proceeds to step S7, and if not, the process returns to step S3.

S7: The DSP 1 performs tape feed deceleration processing and ends this processing (RTS: Return To Subr).
outine). b) Description of the Tape Feed Constant Speed Subroutine FIG. 10 is an explanatory diagram of the tape feed constant speed subroutine.
Hereinafter, the process S11 in FIG. 10 which is the content of the process S3 in FIG.
This will be described according to S15.

S11: When the constant speed of the tape feed starts, the DSP 1 determines whether or not the number of its own tacho pulses during the index pulse period is 500 or less. In this determination, if the number of tacho pulses is less than 500, a tape stop process is performed. If the number is not less than 500, the process proceeds to step S12.

S12: The DSP 1 determines whether the phase of the tacho pulse has been inverted. In this determination, if the phase is reversed (the motor rotates in the reverse direction), a tape stop process is performed, and if not, the process proceeds to step S13. The detection of phase inversion can be performed by providing two sensors whose positions are shifted and detecting the output phase thereof.

S13: The DSP 1 sets the limit state of the on-time of the PWM pulse to the specified number of times (for example, 9 times of 40 μs).
It is determined whether or not 0% or more has continued for 10 times or more. In this determination, if the limit state has continued for the specified number of times or more, the tape stop processing is performed, and if not, the processing S
Move to 14.

S14: The DSP 1 calculates the constant speed running current, and proceeds to the processing S15. S15: The DSP 1 sets the currents of the file motor and the machine motor, and ends this processing.

As described above, despite the fact that the tape is running in the same direction, when the tachometer output is considerably smaller than 1024 pulses while the index pulse is generated once, the tape always runs in the same direction. In spite of this, when the pulse phase of the tacho pulse is reversed, a function to stop both reel motors is provided.

In this magnetic tape device, a voltage value proportional to a reel motor control current value is converted into a PWM pulse, that is, voltage-frequency conversion is performed. For this reason,
The on-time of the PWM pulse period is set to a precision clock (12 MHz).
z clock, see FIG. 5), and when the tape runs out of control, the reel motor continues to rotate at high speed with almost no load, so that the PWM pulse (several tens μm) is used.
s) Since the ON time becomes long and the ON time is almost in the limit state (on duty = 90% or more), the tape stops when this limit state continues for several tens of cycles during the tape constant speed running control. It has a function to make it work.

Further, when the tach pulse of the other reel is output in spite of the output of the tach pulse of one reel, the tape is stopped and the tape runs out of control.
For cutting protection, a function of stopping both reel motors may be provided.

In the case where the encoder pulse of one reel is output but the encoder pulse of the other reel is not output, the tape has a function of stopping the tape, and the tach pulse of one cycle of the encoder pulse is provided. If the count value for counting the numbers is significantly different from the expected value, a function of stopping both reel motors may be provided for tape runaway / cut protection. In this example, the encoder pulse is (15 pulses) / (rotation), and the tachometer pulse number is (1024 pulses) /
(Rotation).

[0082]

As described above, the present invention has the following effects. (1): A control unit for controlling two reel motors for feeding / winding the tape. During the constant speed running of the tape, no pulse was detected from the rotation pulse generating means within a predetermined soft timer time. At this time, since the two reel motors are stopped, even if a pulse from the rotation pulse generating means cannot be detected due to a hardware abnormality or the like, the abnormality can be checked by the soft timer and the tape runaway can be prevented.

(2): A control unit for controlling two reel motors for feeding / rewinding the tape. In spite of detecting a pulse from the rotation pulse generating means of one of the reel motors, the other is controlled. When the pulse from the rotation pulse generating means of the reel motor is not detected, the two reel motors are stopped, so that runaway of the tape due to abnormality of the rotation pulse generating means or the like and protection of the tape cutting can be performed.

(3): A control section for controlling two reel motors for feeding / winding the tape. The rotation pulse is generated at the interval of the generation of the index pulse even though the tape is running in the same direction. When the pulse of the means is smaller than a specified value or when a reverse rotation pulse is detected from the rotation pulse generation means, the two reel motors are stopped. The tape can be protected from cutting.

(4): A control section for controlling two reel motors for feeding / rewinding the tape. The pulse is output from the encoder pulse generating means of one of the reel motors. If no pulse is output from the encoder pulse generating means of the motor, or if the number of pulses of the rotation pulse generating means for one cycle of the encoder pulse generating means is different from the expected value by a specified number, the two reel motors are stopped. Therefore, the rotation of the reel motor can be checked by the rotation pulse generating means and the encoder pulse generating means, so that the tape runaway and the tape cutting protection can be reliably performed.

(5): A control section for controlling the two reel motors for feeding and winding the tape by PWM pulses. During the constant speed running control of the tape, the on-time close to the PWM pulse limit state is set for a specified cycle. When continued, said 2
Since the two reel motors are stopped, it is possible to prevent the tape runaway in which the limit state where the on-duty of the PWM pulse exceeds 90% continues during the tape constant speed running control.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of a magnetic tape device according to the embodiment.

FIG. 3 is an explanatory diagram (part 1) of a magnetic tape control unit according to the embodiment;

FIG. 4 is an explanatory diagram (part 2) of the magnetic tape control unit according to the embodiment.

FIG. 5 is an explanatory diagram of a PWM circuit according to the embodiment.

FIG. 6 is an explanatory diagram of a switching constant current amplifier according to the embodiment.

FIG. 7 is an explanatory diagram of a drive sequence of the brushless motor in the embodiment.

FIG. 8 is an explanatory diagram of a connection of a brushless motor and a tachometer in the embodiment.

FIG. 9 is a flowchart of a tape constant speed running process in the embodiment.

FIG. 10 is an explanatory diagram of a tape feed constant speed subroutine in the embodiment.

FIG. 11 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1a Control unit 21, 22 Reel motor 41a, 91a Index pulse generating means 42a, 92a Rotating pulse generating means 100 Soft timer

Claims (5)

[Claims] 1. A reel unit for feeding / rewinding a tape, a control unit for controlling the two reel motors, and a rotation for generating a pulse for detecting a rotation speed of each of the two reel motor shafts. A pulse generator, and a soft timer determined by a time for performing a prescribed process in the controller, wherein the controller is configured to output the signal from the rotation pulse generator within a predetermined time of the soft timer during the constant speed running of the tape. When no pulse is detected, the two reel motors are stopped. 2. A reel unit for feeding / rewinding a tape, a control unit for controlling the two reel motors, and a rotation for generating a pulse for detecting a rotation speed of each of the two reel motor shafts. A pulse generator, wherein the controller is configured to detect a pulse from the rotation pulse generator of the one reel motor but not detect a pulse from the rotation pulse generator of the other reel motor. A magnetic tape device, wherein the two reel motors are stopped. 3. Two reel motors for feeding / rewinding a tape; a control unit for controlling the two reel motors; and a pulse for detecting a rotation direction and a speed of each of the two reel motor shafts. Rotation pulse generating means, and an index pulse generating means for generating an index pulse by the rotation of the reel motor shaft, the control unit, despite running the tape in the same direction, the index pulse A magnetic tape device for stopping the two reel motors when a pulse of the rotation pulse generating means is smaller than a specified value at a generation interval, or when a reverse rotation pulse is detected from the rotation pulse generating means; . 4. A reel motor for feeding / rewinding a tape, a sensor for detecting the position of each rotating magnetic pole of the two reel motors, and an encoder pulse from an output of the sensor by rotation of the reel motor. An encoder pulse generating means for generating, a control unit for controlling the two reel motors, and a rotation pulse generating means for generating a pulse for detecting a rotation speed of each of the two reel motor shafts, Is a case where a pulse is output from the encoder pulse generating means of the other reel even though a pulse is output from the encoder pulse generating means of one reel, or If the number of pulses of the rotation pulse generating means is different from the expected value by a specified number, the two reels Magnetic tape apparatus, characterized in that stop over data. 5. Two reel motors for feeding / rewinding a tape, a control unit for controlling the two reel motors with PWM pulses, and a pulse for detecting a rotation speed of each of the two reel motor shafts. The control unit is configured to stop the two reel motors when the on-time close to the PWM pulse limit state continues for a prescribed cycle during the tape constant-speed running control. Characterized magnetic tape unit.