JPH07210941A - Control of tape tension between reels - Google Patents

Abstract

PURPOSE:To prevent a tape from damaging even in the case the tape runs at a high speed by providing a nonlinear element, by which the gain is made variable in accordance with the amount of tension error, in a tension control system and strongly controlling the tension when the tension error is large. CONSTITUTION:The tape tension is controlled mainly at the supply side. The tape tension at the supply side is detected from the output of a potentiometer 23 of the supply side. The detected tension is compared with a target tension, and the error signal is inputted to an amplifier 35 through a compensator 36, then a reel motor at the supply side is driven by a motor driver 34 after the amplification to rotate a supply reel. At the take-up side, the speed control and the tension control are performed, and the tape tension is detected from the output of a potentiometer 28 of the take-up side. The detected value is compared with the target value, and the error signal is inputted to a compensator 40 through the nonlinear element 44. The outputs of a compensator 43 of the speed control system and the compensator 40 are added and inputted to an amplifier 39. The output of the amplifier 39 is inputted to a motor driver 38, then a motor 37 for the take-up reel is driven.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for recording and reproducing a signal on a magnetic tape, and more particularly to a tape tension control method for fast-forwarding and rewinding the tape at a high speed. Regarding

[0002]

2. Description of the Related Art In a commercial VTR, an arbitrary tape speed can be selected in a wide range from low speed to high speed in consideration of editing work. Further, a tension sensor is provided on the supply reel side so that the tape tension can be controlled with high accuracy. Further, in some cases, a tension sensor is also provided on the take-up reel side in order to reduce the tension fluctuation during transition.

FIG. 2 is an explanatory view showing an example of such a VTR tape running system. 1 is a rotary drum, 2 is a cassette, 3 is a supply reel, 4 is a take-up reel, and 5 is a magnetic tape. Magnetic tape 5 is supplied reel 3 as shown
Is wound around the rotary drum 1 and wound on the take-up reel 4. Guide posts 6 to 16 for restricting tape running are provided in the tape running path. A tape drive capstan 17 and a pinch roller 18 are provided on the take-up reel side.

Between the guide posts 6 and 7 on the supply side,
A tension pin 19 for detecting the tension is provided. The tension pin 19 is provided at the tip of a tension arm 20 that rotates about a fulcrum 22, and the tension arm 20 is supported by a spring 19. The tension arm 20 is provided with a potentiometer 23 (not shown) that detects the rotation angle of the arm. Depending on the tape tension, the tension arm 2
Since 0 rotates, the output proportional to the tape tension is obtained from the potentiometer 23.

A tension pin 24 is also provided between the guide posts 15 and 16 on the winding side. Since this is the same as the tension pin 19 on the supply side, its description is omitted, but 25 is a tension arm, 26 is a spring, 27 is a fulcrum, and 28 is a potentiometer (not shown).

There are two methods for driving the tape: a capstan drive for feeding the tape 5 between the capstan 17 and the pinch roller 18 and a reel drive for feeding the tape directly between the supply reel 3 and the take-up reel 4. There are two ways. When the tape is fed at a low speed with high accuracy such as recording / reproducing, a capstan drive in which the pinch roller 18 is turned on (pressed) is used. When feeding the tape at high speed such as fast-forwarding and rewinding, the reel drive with the pinch roller off is used.

When the capstan is driven, the tape speed is controlled by controlling the rotation speed of the capstan motor to be constant. The tape tension is controlled to an arbitrary value regardless of the tape speed by controlling the reel motor by feeding back the rotation angle of the tension arm. In the case of capstan drive, since the supply side and the winding side are separated by the capstan, the tape tension can be controlled independently of the supply side and the winding side.

When the reel is driven, the tape speed and the tape tension are controlled by the supply reel motor and the take-up reel motor. A case of fast-forwarding in which the tape is transferred from the supply reel to the take-up reel will be described. By detecting the tape speed and feeding it back to the take-up reel,
The take-up reel motor is controlled so that the tape speed becomes the target speed. The tape tension is controlled by feeding back the position of each tension pin to each reel motor, as in the case of driving the capstan.

However, when the reel is driven, the tension on the supply side and the tension on the winding side are related to each other by the traveling load therebetween. That is, the tensions on the supply side and the winding side cannot be controlled independently. For this reason, when the target values of the tensions on the supply side and the winding side are not appropriate, there is a problem that the errors in the tape speed and the tape tension are large and the running becomes unstable.

As a conventional method for solving these problems, as disclosed in Japanese Unexamined Patent Publication No. 5-128651, the tape tension control system on the winding side is made inoperative during tape running in the pinch-off state. There is a way.

[0011]

However, in the above-mentioned conventional method, when the tape running friction changes depending on the type of tape, the operating environment, etc., the tension on the winding side changes greatly, and in the worst case, the tape There is a problem of damaging the.

An object of the present invention is to stabilize the tension on the winding side and prevent damage to the tape even when the running friction changes.

[0013]

According to the present invention, since the gain varying means for varying the gain of the tension control system on the winding side according to the error in the tension on the winding side is provided, the tension on the winding side is within a certain range. Can be controlled within.

[0014]

In this structure, the gain varying means causes the tension control system on the winding side to operate more strongly when the tension error is large, so that the tension on the winding side can be controlled within a certain range, and the tape is damaged. Can be prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In FIG. 1, the tape running system of FIG. 2 is simplified and a guide post, a fixed head and the like are omitted. V
It is assumed that a fast forward command is sent from the operation panel 48 of the TR. In accordance with the operation command, the system controller 49 generates a tape speed target value, a supply-side tension target value, and a winding-side tension target value which are predetermined. Each target value is converted into a corresponding voltage by the voltage conversion means 45, 46, 47 and input to each servo circuit.

In the case of fast-forwarding in which the tape is fed from the supply reel to the take-up reel, tape speed control and tape tension control on the take-up side and tape tension control on the supply side are performed on the take-up side.

The tape tension is mainly controlled on the supply side.
The tape tension on the supply side is detected from the output of the potentiometer 23 attached to the shaft of the tension arm 20 on the supply side. The detected tension is compared with the target tension, and the error signal is input to the amplifier 35 via the compensator 36. After being amplified by the amplifier 35, the supply side reel motor is driven by the motor driver 34 to rotate the supply reel 3. as a result,
The rotation angle of the tension arm, that is, the position of the tension pin is controlled to a constant position corresponding to the target tension, and the tape tension on the supply side is controlled. Here, the compensator 36 is for stabilizing the tape tension control system on the supply side and adjusting the control characteristics, and normally a phase delay advance element or the like is used.

In FIG. 1, in order to detect the tape speed, a speed detecting roller 32 that rotates as the tape runs is provided. An encoder attached to the shaft of the roller 32 generates a frequency signal that is an integral multiple of the rotation speed of the roller. By inputting this frequency signal to the F / V conversion (frequency / voltage conversion) means 42, a voltage proportional to the tape speed can be obtained. The detected tape speed is compared with the target speed, and the error signal is input to the winding-side amplifier 39 through the compensator 43. After being amplified by the amplifier 39, it is input to the motor driver 38 and the take-up reel motor 37 is rotated to drive the take-up reel 4. Here, the compensator 43 is for stabilizing the tape speed control system and adjusting the control characteristics, and normally uses a phase delay advance element or the like.

On the winding side, tension control is performed simultaneously with speed control. The tension control on the winding side is similar to that on the supply side, except that the tension error is input to the compensator 40 through the non-linear element 44. The tape tension on the winding side is detected from the output of the potentiometer 28 attached to the shaft of the tension arm 25 on the winding side. The detected tension is compared with the target tension, and the error signal is compared with the nonlinear element 44.
Is input to the compensator 40 via. Compensator 4 for speed control system
The output of No. 3 and the output of the compensator 40 of the tension control system are added and input to the amplifier 39. The output of the amplifier 39 is input to the motor driver, and the take-up reel motor is driven. Here, the gain characteristic of the non-linear element 44 is shown in FIG.
This non-linear element has a gain of 0 when the input is within a predetermined value, and a constant gain (gain 1) when the input exceeds the predetermined value.
Is to have. FIG. 5 shows input / output characteristics of the nonlinear element having the gain characteristics shown in FIG. When the tension error is within a certain range, the error is set to 0, and when the tension error is outside the range, the error is output as it is.

At the time of reel driving such as fast forward and rewind,
The relationship between the winding-side tension and the supply-side tension will change if the running friction between them changes. Therefore, the target tension value on the winding side uses a value obtained by adding the average traveling friction between the tension pins 19 and 24 to the target tension value on the supply side.

A case where a tape having an average running friction is run in the control system of FIG. 1 will be described. In this case, the tape tension on the supply side is controlled to the target value, and the tension on the winding side also becomes almost the target value, so the tension error is small. Since the tension error is smaller than the predetermined value (THL), the gain of the nonlinear element 40 is 0, and the tension control on the winding side does not work. Therefore, the tape tension is controlled by the supply reel, the tape speed is controlled by the take-up reel, and the tape tension and the tape speed both stably travel the tape according to the target values.

When the tape running friction becomes large, the winding-side tension becomes larger than the target tension, and a tension error occurs. When the magnitude of this tension error exceeds a predetermined value (THL), the gain of the nonlinear element 40 becomes 1 and the tension control system operates. In this case, since the reel is braked by the tension control on the winding side, the tape speed becomes lower than the target value. In this state, the tension error and the speed error are balanced, the tape runs stably, and the tape tension does not become excessive. In particular,
Even when the tape is stuck to the drum or the like, when the tension increases to some extent, a tension error occurs and the driving force of the reel motor on the take-up side is limited, so that it is possible to prevent the tape from being cut.

On the contrary, when the tape running resistance becomes small, the tape speed becomes higher than the target value and the winding-side tension becomes lower than the target value.

The case of fast-forwarding has been described above.
In the case of rewinding, the relationship between the supply side and the winding side is simply reversed, and the same operation is performed.

According to this embodiment, if the tape running friction is within a predetermined value, the tape runs at the target tape speed, and if the tape running friction changes significantly, priority is given to the control of the tape tension. It can operate to prevent abnormal tape tension.

FIG. 5 is a gain characteristic diagram of a non-linear element having a characteristic different from that of FIG. In this case, the gain becomes 1 and the tension control system operates only when the tape tension becomes excessive, that is, when the tension error exceeds + THL.
FIG. 6 shows input / output characteristics of the non-linear element having the gain characteristic of FIG.

FIG. 7 and FIG. 8 show the characteristics which make the change of the gain at the threshold level (THL) of FIG. 3 gentle, and show the same effect as that of the characteristics shown in FIG. ing.

In the present embodiment, an example in which the tape speed detecting roller 32 is used has been described. However, the rotation of the supply reel 3 and the take-up reel 4 is detected by an encoder provided on the shaft of each reel motor and calculated. A method of detecting the tape speed may be used.

Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the winding-side tension is controlled by the supply-side reel, and both the supply-side tension and the winding-side tension are fed back to the supply-side reel. The tape speed control is performed by the reel on the tape winding side, as in the above-described embodiment.

On the supply reel, the tension of the tape is controlled. An error signal between the supply-side tension detection value and the supply-side tension target value is input to the non-linear element 44. The gain characteristic of the nonlinear element 44 is similar to that shown in FIG. The output of the non-linear element 44 and the tension error signal on the winding side are added and input to the amplifier of the compensator 36 of the tension control system on the supply side.
The output of the compensator 36 is amplified by the amplifier 35 and input to the motor driver 34 to drive the supply reel motor.

On the take-up reel, only the tape speed is controlled. The drive force of the take-up reel is adjusted according to the tape speed error.

If the tape running friction is within a predetermined range,
The tape speed and the tension on the take-up side are controlled to run the tape. At this time, the supply side tension error is within the predetermined range,
The supply-side tension gain becomes 0, and the supply-side tension control system does not operate. When the tape running friction is large, the tension on the supply side decreases and a tension error on the supply side occurs, and the tension error on the supply side is added. As a result, it is possible to prevent the supply side tension from being lowered more than necessary. In this case, the tension on the winding side becomes higher than the target value accordingly. Conversely, when the tape running friction is small, the tension on the supply side increases,
The supply side tension error increases. This error signal is prevented from being added to the supply side and becoming higher than necessary. In this case, the tension on the winding side becomes lower than the target value.

According to this embodiment, the tape can be run while stabilizing the tape speed and the tension on the winding side.
Further, when the tape running friction changes greatly, the winding-side tension can be adjusted to prevent abnormal tape tension.

[0034]

According to the present invention, since the non-linear element for varying the gain according to the magnitude of the tension error is provided, the tension on the winding side is kept within a certain range even when the tape running friction changes. It can be controlled and damage to the tape can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of a tape running system of a VTR.

FIG. 3 is a gain characteristic diagram of a non-linear element.

FIG. 4 is a characteristic diagram of input / output of a non-linear element.

FIG. 5 is a gain characteristic diagram of a non-linear element.

FIG. 6 is a characteristic diagram of input / output of a non-linear element.

FIG. 7 is a gain characteristic diagram of a non-linear element.

FIG. 8 is a characteristic diagram of a gain of a non-linear element.

FIG. 9 is a block diagram showing the configuration of another embodiment of the present invention.

[Explanation of symbols]

1 ... rotary drum, 2 ... cassette, 3 ... supply reel, 4 ...
Take-up reel, 5 ... Magnetic tape, 17 ... Capstan, 18 ... Pinch roller, 20 ... Supply side tension arm, 25 ... Take up side tension arm, 32 ... Speed detection roller, 44 ... Non-linear element, 49 ... System controller .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinsuke Nakagawa 502 Jinritsucho, Tsuchiura City, Ibaraki Prefecture Hiritsu Seisakusho Co., Ltd.

Claims (3)

[Claims] 1. A tension sensor on each of a supply side and a take-up side is provided between a supply reel and a take-up reel, and the two reels are controlled to maintain the tape tension and the tape speed at predetermined values. In a reel-to-reel tape transfer control method for transferring a tape between a supply reel and the take-up reel, a tension error signal between the tension sensor on the supply side or the take-up side and a tension target value corresponding to the tension sensor is calculated. A reel-to-reel tape tension control method characterized in that a supply reel or a take-up reel is controlled on the basis of an output signal from a non-linear element which makes a gain variable in accordance with. 2. A tension sensor on each of a supply side and a winding side is arranged between a supply reel and a take-up reel, and the two reels are controlled to maintain the tape tension and the tape speed at predetermined values. In a reel-to-reel tape transfer control method for transferring a tape between a supply reel and the winding reel, a tension error signal between a supply-side tension sensor and a supply-side tension target value, a winding-side tension sensor, and a winding-side tension target value And a take-up reel are controlled based on a signal obtained by adding the two take-up tension error signals. 3. The non-linear element according to claim 2, wherein either the supply side tension error signal or the winding side tension error signal is input to a non-linear element whose gain is variable according to the magnitude of the error signal. Then, the reel-to-reel tape tension control method for controlling the supply reel or the take-up reel based on the signal obtained by adding the output signal of the non-linear element and the other error signal.