JPH10162452A - Magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the tape tension constant by controlling a reel motor of the take-up side by feeding back so as to keep the tape tension constant which is figured out from a current value of the reel motor at the take-up side. SOLUTION: In a control circuit 8, the detected current value I is divided by the tape winding diameter Rt and this value is defined to the feedback amount and compared with a controlling objective value E preliminarily set so that the tape tension Tt becomes the desired value. When the feedback amount <E, a driving voltage of the supply side reel motor 4 in the forward direction is lowered. When the feedback amount >E, a load due to a reel base 4 at the supply side is increased/decreased by controlling to increase the driving voltage of the supply side reel motor 4, and as the result, by the operation to increase/decrease the tension Ts at the position right after the supply side reel base 3, the tension Tt at the position before the take-up side reel base 1 is kept constant independently of the tape winding position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape take-up control technique for a video tape recorder (hereinafter, VTR) and the like. It belongs to the technical field of tape tension control when performing high-speed tape feeding.

[0002]

2. Description of the Related Art As a conventional magnetic recording / reproducing apparatus using a magnetic tape such as a VTR, there is a so-called direct drive system in which a reel motor is provided on each of a take-up reel and a supply reel.

In this direct drive system, a reel base on which a magnetic tape is wound is directly driven by a reel motor,
Since the supply-side reel motor is rotated by an external force, a back electromotive voltage is generated in the coil of the supply-side reel motor, and this acts as a self-braking torque that prevents rotation by the external force.

The self-braking torque increases as the number of rotations of the motor increases. In addition, the self-braking torque further increases due to a change in the winding of the supply-side reel.
The tape tension increases toward the end of the tape as shown in FIG.

As described above, since the tape tension greatly changes depending on the winding position of the tape, the tape may be adversely affected, such as damage to the tape and unstable running of the tape.

Therefore, as a method of controlling the tension of these magnetic tapes, a method of providing a tape tension detecting device such as a tension post in a tape path and controlling a reel motor or the like based on the detection output is generally used.

However, in this case, it is necessary to provide a dedicated means such as a tension post and a detection sensor, which requires an installation space, the number of parts, costs, and also poses a problem in terms of reliability.

Japanese Patent Application Laid-Open No. Sho 6 (1994) discloses a method for controlling the tape tension during high-speed tape feeding without using these sensors.
There is one disclosed in Japanese Patent Application Laid-Open No. 2-239354.
In this technique, the supply reel motor, which is a load during high-speed tape feeding, is subjected to current control according to its own rotation speed, thereby suppressing an increase in the load at the end of the tape and keeping the tape tension substantially constant.

The tape drive control system includes a tape drive control system for controlling the tape speed by the output of an FG detector attached to each reel motor for the purpose of keeping the winding time of the entire tape constant. Is called the average speed constant control. It is called the method of controlling the take-up reel motor so that (1 / Nt) + (1 / Ns) = C, or it is called the two-step constant control (1 / Nt) ² + (1 / Ns) ² = C Here, a method of controlling so that Nt: the rotation speed of the take-up reel motor Ns: the rotation speed of the supply-side reel motor C: a constant is known.

However, in any of the above-described tape drive control systems, the number of revolutions of the supply-side reel motor increases as the winding of the tape ends, so that the load on the entire traveling system due to the braking torque of the supply-side reel motor is increased. Certain tape tensions also increase with this and are not constant.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has been made in consideration of the above circumstances, and has been made in consideration of the above-described circumstances. A technical problem is to eliminate a change in the tension and keep the tape tension constant.

[0012]

According to the present invention, there is provided a tape drive of a magnetic recording / reproducing apparatus for winding a magnetic tape from a supply reel to a take-up reel. A take-up reel motor that drives the supply reel, a supply reel motor that drives the supply-side reel,
A winding diameter detecting means for detecting a winding diameter of the winding-side reel motor; and a current detecting means for detecting a current of the winding-side reel motor, and a value detected by the winding diameter detecting means during high-speed tape running. And a control amount of the supply-side reel motor is calculated based on a value detected by the current detection means.

A value obtained by dividing the value detected by the current detecting means by the value detected by the winding diameter detecting means is compared with a predetermined value. If the predetermined value is larger, the drive voltage of the reel motor is determined. Is increased, and when the predetermined value is small, the drive voltage of the reel motor is reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a magnetic recording / reproducing apparatus according to the present invention will be described with reference to FIG.

FIG. 1 is a configuration diagram of a reel driving device of a magnetic recording / reproducing apparatus according to the present invention.

In the drawing, (1) is a take-up reel base, which is driven directly by a take-up reel motor (2) or via a gear or the like.

Reference numeral (3) denotes a supply-side reel base, which is driven directly by a supply-side reel motor (4) or via a gear or the like.

(5) is a magnetic tape wound around a supply side and a take-up side reel.

(6) and (7) are motor drive circuits,
The take-up reel motor and the supply-side reel motor are driven in accordance with an instruction from the control unit (8).

The motor current of the supply-side reel motor (4) and the take-up-side reel motor (2) is a resistance (9).
The voltage is converted into a voltage by (10) and (10) and is taken into the control unit (8) through the buffer amplifiers (11) and (12).

(13) and (14) are FG detectors,
An FG pulse is generated by rotation of the take-up reel motor (2) and the supply-side reel motor (4), and the FG pulse is input to the control unit (8).

The magnetic tape (5) forms a traveling system by a tape path composed of several tape guides (15) and a rotary cylinder (16).

In this tape path, when the tape is being fed on the take-up reel base (1), the tape tension Tt before the take-up reel base (1) and the tape immediately after the supply-side reel base (3). The relationship with tension Ts is
Assuming that a constant determined by a tape guide (15), a rotary cylinder (16), and the like constituting a tape path is k (k> 1), there is a relationship of Tt = k · Ts.

Here, to keep the tape tension Tt constant means to make the take-up reel base (1) always give a constant force to the tape, and to take up the take-up reel base (1).
Assuming that Lt is the torque at which the tape is generated and Rt is the tape winding diameter of the take-up reel, the relationship is Tt = Lt / Rt.

The torque generated by the take-up reel motor (1) is proportional to the motor current I.
If Kt, Tt = Kt × I / Rt.

Therefore, if I / Rt is controlled to be constant, Tt can be made constant.

The take-up reel motor (1) is driven by a voltage supplied from a motor drive circuit (6), and a motor current flows through a resistor (9).

Therefore, the resistance (9) and the buffer (1)
The current I can be detected by taking the voltage of the motor current detecting means constituted by 1) into the control circuit (8).

Rt can be calculated from the following two relational expressions that hold between the parameters.

Π (Rt ² −R 0 ² ) + π (Rs ² −R 0 ² ) = W × L Rt × Nt = Rs × Ns Rt, Rs: Tape winding diameter R0: Reel hub diameter Nt, Ns: Reel rotation speed W: Tape thickness L: Tape length Rt = {(W × L / π + 2R0 ² ) / (1 + Nt ² / Ns ² )} The tape reel is then operated by the above-described apparatus according to the interrupt control processing routine of FIG. Is driven to keep the tension value given to the tape by the take-up reel constant.

This interrupt control routine is repeatedly executed by the control unit (8) for each interrupt generated at regular time intervals.

First, in step 1, the rotation speed Nt of the take-up reel
And the number of rotations Ns of the supply reel by an FG detector (13),
It is detected using the output of (14) and read as the number of revolutions of each reel.

In step 2, the output value of the buffer amplifier (11) is detected and read as the motor current value I.

Then, in step 3, based on these read values, the tape winding diameter Rt is obtained by the following calculation.

Rt = {(W × L / π + 2R0 ² ) / (1 + Nt ² / Ns ² )} where R0 is a reel hub diameter, Nt and Ns are reel rotation speeds, W is a tape thickness, and L is a tape length. Which is a preset value.

In step 4, the value obtained by dividing the current value I read in step 2 by the value of Rt obtained in step 3 is compared with a predetermined target value E.

As a result of the comparison, if the target value E is larger,
In step 5, control is performed to decrease the motor supply voltage. If the target value E is smaller, control is performed to decrease the motor supply voltage in step 6, and the interrupt processing routine ends.

Further, every time an interrupt signal is input, the processing of this processing routine is repeated.

According to the above control, a value obtained by dividing the detected current value I by Rt is obtained in the control circuit (8), this is used as a feedback amount, and Tt is set in advance so as to have a desired value. When the feedback amount is smaller than E, Tt is lower than a desired value. Therefore, the drive voltage in the feed direction of the supply-side reel motor (4) is reduced. When the feedback amount is larger than E, Tt is reduced. Since the drive voltage of the supply-side reel motor (4) is controlled to be higher than the desired value, the load on the supply-side reel base (4) increases / decreases, and as a result, the supply-side reel base (3) Immediate Ts
A stable feedback loop is formed by the action of increasing / decreasing the value of, and Tt is kept constant regardless of the tape winding position.

[0040]

As described above, according to the magnetic recording / reproducing apparatus of the present invention, the tape tension is calculated from the current value of the take-up reel motor and the take-up reel diameter, and the supply-side reel is kept constant. By performing feedback control of the motor, it is possible to maintain a constant tape tension regardless of the tape winding position even with high speed tape running by reel drive with a simple configuration, reducing damage to the tape and ensuring stable tape running. It can be carried out.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetic recording and reproducing apparatus according to the present invention.

FIG. 2 is a control flowchart of the magnetic recording / reproducing apparatus of the present invention.

FIG. 3 is a view showing a tape tension-tape winding position characteristic by a conventional device.

[Explanation of symbols]

 1. Take-up reel base 2. Take-up reel motor 3. Supply side reel base 4. Supply side reel motor 5. Magnetic tape 6. Motor drive circuit 7. 7. Motor drive circuit Control unit 9. Resistance 10. Resistance 11. Buffer amplifier 12. Buffer amplifier 13. FG detector 14. FG detector 15. Tape guide 16. Rotating cylinder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Yamanaka 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A tape drive for a magnetic recording / reproducing apparatus for winding a magnetic tape from a supply reel to a take-up reel, the take-up reel motor driving the take-up reel, and the supply reel being driven. A supply reel motor; a winding diameter detecting means for detecting a winding diameter of the winding reel motor; and a current detecting means for detecting a current of the winding reel motor. A control amount of the supply-side reel motor is calculated based on a value detected by the means and a value detected by the current detection means. 2. The method according to claim 1, wherein a value obtained by dividing the value detected by said current detecting means by a value detected by said winding diameter detecting means is compared with a predetermined value. 2. The tape drive according to claim 1, wherein when the predetermined value is small, the drive voltage of the reel motor is reduced. 3. A method in which a value obtained by dividing a value detected by the current detecting means by a value detected by the winding diameter detecting means is compared with a predetermined value at predetermined time intervals. 3. The tape drive according to claim 2, wherein the drive voltage of the motor is increased, and when the predetermined value is small, the drive voltage of the reel motor is reduced.