JPH03108146A - Tape tension controller for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To apply equal control accuracy regardless of a feed direction by controlling a gain switching means and correcting the gain of a tension control system corresponding to the feed direction of a magnetic tape. CONSTITUTION:A microcomputer for system control as the control means 19 outputs a control signal es of 'L' when an ordinary reproducing operation is commanded with an operating key, and the control signal es of 'H' when a reverse tape feed operation is commanded. Meanwhile, the gain switching means 18 inputs the input signal ei of a tension sensor 7, and is controlled corresponding to the control signal es of the control means 19. When the signal es is set at 'H', an operation is performed so as to heighten the control gain of a motor 9 for reel driving corresponding to the signal ei. Then, when the tape is fed in the reverse direction, the reduction of a loop gain can be corrected by performing the switching control of resistors 35, 36 with the transistor 24 of the switching means 18. In such a way, the equal tension control can be applied regardless of the feed direction of the tape.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tape tension control device for a single-rotation head type magnetic recording/reproducing device, and particularly to a tape tension control device for realizing stable tension control regardless of the running direction of the tape. Regarding a control device.

(Prior Art) In rotary head type magnetic recording and reproducing apparatuses such as VTRs and DATs, it has become common practice to control the tape tension on the tape feeding side in consideration of tape running stability, head life, etc. ing.

FIG. 2 shows a schematic configuration of the tape tension control. In the same figure, 1-a is a cylinder, 1
-b, 1-c are the magnetic heads 2 and 3 on the tape winding side and the reel stand on the tape supply side, respectively; 4 is a tension pin; 5 is a spring; 6 is the intersection of the arms on which the tension pin 4 moves;
7 is a tension sensor composed of a magnet 14 and a magnetic resistance element 15, etc.; 8 is an error amplifier; 9 is a reel drive motor; 10 is a capstan servo circuit; 11 is a capstan motor; 12 is a capstan; 13 is a A pinch roller 16 and a magnetic tape 17 indicate a reference voltage of the error amplifier 8.

The tape tension control device shown in FIG. 2 detects the position of the tension pin 4 with a tension sensor 7, and operates the reel drive motor 9 so that the position of the tension pin 4 is at a predetermined position. For example, when the tension at the tension pin 4 decreases, the tension pin 4 is returned in the direction a in the figure by the action of the spring 5. At this time, the magnetoresistive element 15 of the tension sensor 7 moves in the direction a in the figure in accordance with the rotation of the arm of the tension pin 4, so the area facing the magnet 14 increases and its detection output e increases. As a result, the output of the error amplifier 8 increases, the torque of the reel drive motor 9 increases, the torque BT transmitted to the reel stand 3 increases, and the tension pin 4 is corrected in a direction in which the tension increases. Conversely, when the tension pin 4 moves in the direction b, which increases the tension, eM decreases and the torque of the reel drive motor 9 decreases, so the tension pin 4 is corrected in the direction of decreasing tension. In this way, in the device shown in FIG. 2, the movement of the tension pin 4 is detected by the tension sensor 7, and the torque of the reel drive motor 9 is controlled by negative feedback based on the control signal to adjust the position of the tension pin 4. In other words, control is performed so that the tape tension remains constant. Of course, the setting of this tension value is determined by the setting of the reference voltage 17 of the error amplifier.

By the way, in the control shown in FIG. 2, if an attempt is made to control the tape tension at the position of the tension pin 4 to be the same for the tape traveling in directions A and B in the figure, the tension will be increased due to torque ripple of the reel drive motor 9, etc. The disadvantage is that the control accuracy varies.

This point will be explained below.

FIG. 3 shows a block diagram of the tension control system of FIG. 2. The tension amplification factor in the figure is the second
The winding of the guide pin on the way from the tension F2 to the tension pin 4 at the cassette exit in the figure means the magnification that increases due to etc., but during normal playback (
The tape running direction is the direction B in Figure 2).If this value is β, then the tape running direction is the opposite direction to that during normal playback (B in Figure 2).
direction), it becomes 1/β.

Therefore, the tension variation ΔFG at the tension pin 4 with respect to the torque ripple ΔT of the reel drive motor 9 during normal playback is.

This will increase to β2 compared to the time of reproduction.

Therefore, the tension variation ΔFG' at the tension pin 4 with respect to the motor torque ripple ΔT' when the tape runs in the opposite direction to normal playback is as follows.

On the other hand, if the tape runs in the opposite direction to normal playback, and the tension of the tension pin 4 is controlled to be the same as normal playback, it is natural that the control reference voltage 17 must be changed, and this value will not change during normal playback. On the other hand, it becomes approximately β2. This means increasing the operating torque of the reel drive motor 9 to β81, and correspondingly, the torque ripple of the motor becomes normal.

As is clear from equations (1) and (2), when the tape is run in the opposite direction to normal playback, the control accuracy of the tension pin 4 due to torque clips of the motor increases by β2 times. It will get worse.

Incidentally, related devices of this type include, for example, Japanese Utility Model Publication No. 63-38428 and U.S. Pat. No. 4,789,826.

[Problem to be solved by the invention]

As mentioned above, the conventional technology does not take into consideration the accuracy of tension control in the tape running direction, and when attempting to control the tape tension at the tension pin position to be the same for forward and reverse tape running, it is difficult to There is a problem in that the control accuracy of tape tension deteriorates when traveling in the opposite direction compared to traveling in the opposite direction.

An object of the present invention is to provide tension control that eliminates the above-mentioned drawbacks and that can obtain the same control accuracy in both directions even when the tape tension at the tension pin position is controlled the same for forward and reverse running of the tape. The goal is to provide equipment.

[Means to solve the problem]

In order to achieve the above object, the tension-controlled n@path according to the present invention is characterized in that the loop is provided with a gain switching means so that the gain of the loop is varied depending on the direction of tape running.

In other words, the deterioration of tension control accuracy when the tape is run in the opposite direction to normal playback is due to the system's open-loop gain necessarily decreasing to 1/β2, and the present invention solves this problem. This is corrected by switching the gain.

[The operational gain switching means is controlled by a control means such as a system controller, and is controlled so that its gain is increased during normal playback (the tape is running in the forward direction) when the tape is running in the opposite direction.

By setting the gain increase value for 1 normal playback to β2, the denominator of the above equation (2) becomes β2 of the denominator of the equation (1), so that the tape is positive.

Even when the tape tension at the tension pin position is controlled to be the same for reverse running, the same control accuracy can be obtained in both directions.

〔Example〕

Hereinafter, a specific embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an embodiment of the present invention.

In the figure, 18 is a DC power supply 20. Amplifiers 21 and 222 Phase inverter 23. Transistors 24 to 27. Gain switching means is comprised of resistors 28 to 36, control means 19 is comprised of a system control microprocessor, etc., and the same reference numerals as in FIG. 2 refer to the same parts.

The structure and operation of each part will be explained below.

The system control microprocessor as the control means 19 outputs a control signal eB of ``Lyt'' when a normal playback operation is commanded by an operation key, and ``'H'' when a tape running operation opposite to the normal playback is commanded. At the same time, it also controls the capstan servo circuit 10.

Capstan servo times lf! 110 is a capstan motor 11. That is, the capstan 12 is controlled to rotate at a constant speed, and when normal playback operation is commanded by the operation key in response to a control signal from the control means 19, the capstan is rotated in the direction a in the figure to play the tape 16. The tape 16 is caused to run at a constant speed in the direction of A, and when the tape running command is opposite to the normal reproduction operation, the capstan 12 is rotationally controlled in the direction of C in the figure to cause the tape 16 to run at a constant speed in the direction of B. The constant speed rotation control of the capstan 12 is specifically configured by negative feedback control using a rotation speed detector (FG) of the capstan motor 11, and the forward and reverse rotation control of the capstan 11 is performed by the capstan motor 11. This is done by, for example, reversing the direction of the egg motion current, but the details are well known and are not directly related to the gist of the present invention, so details will be omitted.

The gain switching means 18 inputs the control signal ei of the tension sensor 7, and according to the control signal es of the control means 19,
When e8 is 11 HPl compared to the case where t L 11, it operates to increase the control gain of the reel driving motor 9 with respect to ei. In other words, in FIG. 1, the reel drive motor 9 is controlled by current $ according to ei, and the voltage-current conversion gain is as follows: When es is "L11", R..I R,.° (3) R,, R33R3°.

On the other hand, when eB is "H", the transistor 24 is conductive and the resistor 34 is connected in parallel to the resistor 33.
Its voltage-current conversion gain is R121RJ5
Fung (4n RJI R33
/ R34Rss, and from equations (3) and (4), e is l/ l-l11
The current-voltage conversion gain at the time of reLto compared to the time of reLto increases according to the value of the resistor R33, R, , as shown in the following equation.

Note that the resistors 28 to 3o, the transistor 27, and the phase inverter 23 are used to control the same tape tension at the tension pin 4 position when the tape is run in the direction and the direction B, as described above. In normal reproducing operation when seg, which switches the reference voltage necessary for The voltage value (v8) is obtained by dividing the DC 'Il source by the value of the resistor 28 and the parallel value of the resistors 29 and 30, and 51= is "
In the case of "II", that is, when the tape is running in the reverse direction of normal playback, the transistor 27 is cut off and the reference voltage becomes the divided voltage value (■2) of the resistors 28 and 29, compared to when e is "L". Its value becomes large (V,>V□).

Also, tension pin 4. The tension control operation by the tension sensor 7, reel drive motor 9, etc.
This is the same as the case shown in the figure.

In the above planting, when a normal reproduction operation is commanded by the operation key, the capstan 12 rotates in the direction a and the tape 1G runs in the direction A. At the same time, the control signal e8 is
L'' is output, the reference voltage of the amplifier 21 of the gain switching means 18 is set to vl, and its control gain is set as shown in equation (3). Tape tension control is performed.

Next, when a tape running operation opposite to normal playback is commanded by the operation key, the capstan 12 rotates in the direction b and the tape 16 runs in the direction B.

At the same time, the control signal e is output as 'H', the reference voltage of the amplifier 21 of the gain switching means 18 is set to v2, and its control gain is set higher than normal reproduction as shown in equation (4). Tape tension control operation is performed by negative feedback control via the reel drive motor 9.

Here, regarding the specific constants of the resistors 28 to 3o,
Considering the sensitivity of the reel drive motor 9 and the tension sensor 7, the above reference voltage V is set such that the tape tension at the tension pin 4 is the same even when the tape is run in the direction and the direction B. □ and V are set to the obtained values. Moreover, the resistors 33 and 34 are also specifically set so that the voltage-current conversion gain ratio K by gain switching shown in equation (5) is equal to β2 according to the value of the tension amplification factor β described above. It is something that will be done.

One embodiment of the present invention has been described above. In the embodiment shown in FIG. 1, an example is shown in which the gain switching means 18 is configured with a voltage-current converter, but this is not particularly limited. In such a case, the gain of the drive amplifier can be controlled by switching. Further, in FIG. 1, the voltage-current conversion gain is switched by controlling the transistor 24, but this is not particularly limited. For example, the resistor 31. Alternatively, the gain of the error amplifier 21 may be switched and controlled by switching the value of the resistor 32.

Furthermore, it is also possible to control the current-current gain by switching and controlling the value of the resistor 35 or the resistor 3G, and various modifications can be easily made without changing the gist of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, even when the tape is run in the opposite direction to normal playback, the decrease in loop gain that inevitably occurs is compensated for by the switching control of the gain switching means, so that the tension Even when the tape tension at the pin position is controlled in the same way as during normal playback, the same tension control accuracy can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of a conventional general tension control device, and FIG. 3 is a block diagram showing a block diagram of the tension control system shown in FIG. 16... Tape, 4... Tension pin, 7... Tension sensor, 9... Reel working motor, 18... Gain switching means. 19...Control means. tsu

Claims (1)

[Claims] 1. A magnetic recording and reproducing device that records and reproduces signals on a magnetic tape using a head installed on a rotating cylinder, which includes a tension control mechanism including a magnetic tape tension sensor and a reel drive means. and a tape tension control device comprising a tape tension control system that controls the tension of the magnetic tape by controlling the reel drive means according to the output signal of the tension sensor,
Magnetic recording comprising a gain switching means and a gain control means, the gain switching means being controlled by the gain control means to vary the gain of the tension control system according to the running direction of the magnetic tape. Tape tension control device for playback equipment.