JP2768987B2 - Tape tension control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape recording / reproducing device using a magnetic tape as a recording medium, and relates to a tape tension control device for controlling a tension applied to the magnetic tape. It is.

[Conventional technology]

In a conventional magnetic tape recording / reproducing apparatus using a magnetic tape as a recording medium, the tape tension is controlled to be constant in order to stabilize the running of the magnetic tape during recording and reproduction on the magnetic tape. Conventional tape tension control devices that perform such control include those using mechanical servos and those using electric servos that electrically control actuators such as motors.

In the tape tension control device using the above mechanical servo, the winding diameter of the magnetic tape changes with the winding operation of the magnetic tape on the reel, so that the tape tension changes accordingly, and stable tape tension control can be performed. It cannot be done. In contrast, a tape tension controller using an electric servo constantly monitors the tape tension with a tape tension sensor, so that the tape tension can be kept constant, making it suitable for tape tension control of magnetic tape. Has become.

That is, as shown in FIG. 2, a tape tension control device using an electric servo drives a reel motor 4 based on a tape tension sensor 1, which detects the tension of a magnetic tape, an amplifier 2, and an output voltage of the amplifier 2. And a three-phase reel motor 4 for rotating a tape reel for winding the magnetic tape.

As shown in FIG. 3, the tape tension sensor 1 takes the value of the detected tape tension on the horizontal axis,
The graph has a characteristic indicated by a curve P on a graph in which the value of the output voltage is plotted on the vertical axis. Amplifier 2, the output voltage of the tape tension sensor 1 is input to the non-inverting input terminal 2a, for example, V _1, reference voltage input to the inverting input terminal 2b
The difference is amplified from V ₀ and amplified, and the amplified output voltage is output to the motor driver 3. The motor driver 3 drives the reel motor 4 according to the voltage input from the amplifier 2. As a result, a pulling force acts on the magnetic tape in a direction opposite to the running direction. When such force is applied, the tension is increased according to the magnetic tape, for example, a T _2. Thus, the output voltage from the tape tension sensor 1 is smaller than V _2, and the previous output voltage V _1. Therefore, the driving force of the reel motor 4 is reduced, and the tape tension is reduced.

As described above, in the tape tension control apparatus according to electric servo, the output voltage will like becomes equal to the reference voltage V ₀ operation of the tape tension sensor 1 is performed, so that, for the magnetic tape always constant Tension is added.

[Problems to be solved by the invention]

However, in the above-described conventional tape tension control device, the magnetic tape becomes slack for some reason,
When the servo is applied from that point on, a force is applied to the magnetic tape in a direction to increase the tension. That is, at this time, the reel actually rotates in the reverse direction. As a result, a very large tension is applied to the magnetic tape, although transiently, and there is a problem that the magnetic tape and the magnetic tape traveling system may be damaged.

[Means for solving the problem]

The tape tension control device of the present invention, in order to solve the above-described problems, by controlling the voltage of a reel motor that rotates a reel around which a magnetic tape is wound,
In a tape tension control device that performs a tension control operation of controlling the tension of the magnetic tape to be constant, a slack detection unit that detects a slack state of the magnetic tape, and when the slack state of the magnetic tape is detected by the slack detection unit, Control release means for releasing the tension control operation.

(Operation)

According to the above configuration, when the slack detecting means does not detect the slack state of the magnetic tape, the tension control operation for controlling the tension of the magnetic tape to be constant is performed. On the other hand, when the slack detecting means detects the slack state of the magnetic tape, the control canceling means cancels the tension control operation. Thus, it is possible to prevent a large tension from being applied by the tension control operation when the magnetic tape is slackened.

〔Example〕

One embodiment of the present invention will be described below with reference to FIGS. 1 and 3.

As shown in FIG. 1, a tape tension control device according to the present invention includes a tape tension sensor 10 for detecting the tension of a magnetic tape, an amplifier 11, a slack detector 12 as a slack detecting unit, and a control releasing unit as a slack detecting unit. , A three-phase motor driver 14, and a three-phase reel motor 15.

The tape tension sensor 10 has the characteristics shown in FIG.

Amplifier 11 is an operational amplifier, a reference voltage V ₀ from the power supply 18 is applied to the inverting input terminal 11b, the non-inverting input terminal 11a
Output voltage V _s of the tape tension sensor 10 is applied to.

The sag detector 12 includes a voltage comparator 16 and an inverting input terminal 16.
The comparison voltage V _ref consist power supply 17 which supplies to b, the output voltage V _s of the tape tension sensor 10 to the non-inverting input terminal 16a
Is applied, and the output voltage is changed to the control terminal 13 of the changeover switch 13.
Output to c. Comparison voltage V _ref of the is set to the critical value of the output voltage V _s of the tape tension sensor 10 can be regarded as a state that does not loose the magnetic tape, comparing the output voltage V _s of the tape tension sensor 10 a voltage V _ref Is exceeded, it is assumed that the slack of the magnetic tape has occurred. Then, the sag detector 12 detects the voltage V _s
If There lower than the comparison voltage V _ref, i.e. when no loose magnetic tape, while the output voltage and Low, if the voltage V _s is higher than the comparison voltage V _ref, i.e., when there is a loose magnetic tape, the output voltage It is set to High.
The relationship between the comparison voltage V _ref and the reference voltage V ₀ has a V ₀ <V _ref.

The changeover switch 13 has selection input terminals 13a and 13b, a control terminal 13c, and an output terminal 13d.
The output voltage of the amplifier 11 is applied to a, and the selection input terminal 13
The voltage E supplied from the power supply 19 is applied to the
The output voltage of the slack detector 12 is applied to 13c.
The output terminal 13d is connected to the input of the motor driver 14. When the reel motor 15 is driven by the motor driver 14 based on the voltage E,
The voltage is set so that the reel motor 15 rotates slowly with a small driving force so as not to apply a large tension to the magnetic tape in a direction opposite to the tape running direction. And
The changeover switch 13 is configured such that when a high voltage is applied to the control terminal 13c, the output terminal 13d is switched to the selection input terminal 13b, and when a low voltage is applied to the control terminal 13c,
The output terminal 13d is switched to the selection input terminal 13a.

The motor driver 14 is connected to the output terminal 13 of the changeover switch 13.
The read motor 15 is rotated in the direction opposite to the running direction of the magnetic tape in accordance with the voltage input from
Numeral 15 is driven by the motor driver 14 to rotate the reel of the magnetic tape.

Then, the tape tension sensor 10, the amplifier 11, the changeover switch 13, the motor driver 14, and the reel motor 15
The path of the output terminal V _s of the tape tension sensor 10
Is set to be equal to the reference voltage V ₀ , that is, a tension servo system for controlling the tape tension to be constant.

In the above configuration, when the magnetic tape does not sag, tension is generated in the magnetic tape,
Output voltage V _s of the tape tension sensor 10, the voltage at the inverting input terminal 16b of the voltage comparator 16 in the slack detector 12 V
_It becomes lower than _{ref, and} the output voltage of the slack detector 12 becomes Low. Therefore, the output terminal 13d of the changeover switch 13 is switched to the selection input terminal 13a side, and the tension servo for the magnetic tape is performed.

If the output voltage V _s of the tape tension sensor 10 is input to the non-inverting input terminal 11a of the case for example with V _1, the amplifier 11 and the reference voltage V ₀ which is input to the inverting input terminal 11b and the voltages V ₁ And amplifies the difference, and outputs the amplified output voltage to the motor driver 14 via the changeover switch 13.
The motor driver 14 drives the reel motor 15 according to the voltage input from the amplifier 11. As a result, a pulling force acts on the magnetic tape in a direction opposite to the running direction, and the tension applied to the magnetic tape increases. Then, when the tape tension is, for example, T _2, the output voltage from the tape tension sensor 10 becomes smaller voltage V ₂ than the previous output voltage V _1. Therefore, the driving force of the reel motor 4 is reduced, and the tape tension is reduced. In this way, the magnetic tape is controlled so that a constant tension is always applied.

On the other hand, when the slack is generated on the magnetic tape, the output voltage V _s of the tape tension sensor 10, compares the voltage V _ref
And the output voltage of the slack detector 12 becomes High. Accordingly, the output terminal 13d of the changeover switch 13 is switched to the selection input terminal 13b, and the tension servo for the magnetic tape is released. As a result, the constant voltage E is input to the motor driver 14, and the motor driver 14 slowly rotates the reel motor 15 in the reverse direction based on the constant voltage E. By slowly rotating the reel motor 15 reversed, go and eliminates the slack of the magnetic tape, the tape tension increases gradually in response to this, the output voltage V _s of the tape tension sensor 10 is gradually decreased Become. In this process, since the driving force of the reel motor 15 is small, a large tension is not applied to the magnetic tape,
Damage to the magnetic tape and the magnetic tape traveling system can be avoided.

Thereafter, when the output voltage V _s of the tape tension sensor 10 is lower than the voltage V _ref, the output voltage of the slack detector 12
Invert from High to Low. At this time, the output terminal 13d of the changeover switch 13 is switched to the selection input terminal 13a side, and the tension servo for the magnetic tape is restored.
As a result, the reel motor 15 is driven by the motor driver 14 according to the output voltage of the amplifier 11.

In this embodiment, the voltage E of the power supply 19 is set to a predetermined value, but the voltage E may be 0V.

〔The invention's effect〕

As described above, the tape tension control device of the present invention controls the tension of the magnetic tape by controlling the voltage of the reel motor that rotates the reel around which the magnetic tape is wound. In the control device, a slack detection unit that detects a slack state of the magnetic tape, and when the slack state of the magnetic tape is detected by the slack detection unit,
And a control release means for releasing the tension control operation.

Therefore, even if the magnetic tape becomes slack, no abnormal force is applied to the magnetic tape, and damage to the magnetic tape and the running system of the magnetic tape can be prevented, and the reliability of the magnetic tape running system can be improved. The effect that it can improve is produced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a block diagram showing a tape tension control device. FIG. 2 shows a conventional example and is a block diagram showing a tape tension control device. FIG. 3 is a characteristic diagram of the tape tension sensor shown in FIG. 1 and FIG. 10 is a tape tension sensor, 11 is an amplifier, 12 is a slack detector (slack detecting means), 13 is a changeover switch (control releasing means), 14 is a motor driver, and 15 is a reel motor.

Claims (1)

(57) [Claims] 1. A tape tension control device which performs a tension control operation for controlling a tension of a magnetic tape to be constant by controlling a voltage of a reel motor for rotating a reel around which the magnetic tape is wound. Slack detection means for detecting
A tape tension control device comprising: a control canceling unit that cancels a tension control operation when a slack state of the magnetic tape is detected by the slack detecting unit.