JPH0520741A - Magnetic recording / reproducing device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The tape tension on the recording or reproducing head is detected by detecting the load current of the capstan motor driving the magnetic tape in the magnetic recording / reproducing apparatus and controlling based on this. Is controlled to be constant. [Structure] FIG. 1 shows an embodiment of the present invention. The magnetic recording tape 2 is loaded via the posts between the supply and take-up reels 1 and 22, the tension detector, the rotating drum 9, the longitudinal track recording / reproducing heads, and the timer roller 19, and the capstan motor 19 is installed. Driven by. In order to keep the tape tension on the rotating drum 9 constant, the load current of the capstan motor 19 is detected by the current detector 28, and the tension set value is varied based on the detected value to perform tension control. [Effect] The effects of differences in tape friction coefficient, running friction, etc. can be corrected, and the tape tension on the rotating drum can be controlled to be constant.

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, and more particularly to a magnetic recording / reproducing apparatus suitable for tape tension of a magnetic tape.

[0002]

2. Description of the Related Art In conventional tape tension control in a magnetic recording / reproducing apparatus, a potentiometer attached to a tension arm between a supply reel and a rotating drum controls the output voltage to a command value. It was Also, in simple machines such as consumer machines, a control system using a brake belt is adopted.

However, in any case, the tension control is not performed on the rotating drum that should be controlled, so that the difference in the tape friction coefficient, the change with time of each post, and the brake belt method are used. Cannot detect and control changes in tape tension due to changes over time in the brake belt and brake drum. Therefore, JP-A-2-23
As shown in No. 2844, a method of controlling the tape tension by the load current of the drum has been proposed.

[0004]

However, even in such a method, it is difficult to consider the influence of the air film generated between the magnetic tape and the rotation of the drum. According to the experiments by the applicant, it is very difficult to correlate the tape tension change on the drum and the rotary drum motor load current change except for the extremely slow tape speed, and it is difficult to accurately perform the correlation.

The present invention correlates the magnetic tape friction coefficient and the friction change of the posts of the tape running system by changing the load current of the capstan motor that directly drives the magnetic tape, and changes the tape tension set value. However, the purpose is to maintain a constant tape tension on the rotating drum.

[0006]

In order to achieve the above object, means for detecting a load current of a capstan motor for driving a magnetic tape is provided, and the load current detection value is input to a tape tension setting means, By changing the tape tension set value, the tension of the magnetic tape wound around the rotary cylinder is controlled.

[0007]

[Operation] The tape tension change from the supply reel to the capstan motor due to the change over time of the tape friction coefficient, the post of the tape running system, the guide, etc. is detected by the change of the load current of the capstan motor driving the magnetic tape. By comparing this detected value with the optimum setting value and varying the tape tension target value with this difference value,
The tape tension on the rotating drum can be kept constant.

[0008]

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 schematic view showing a tape running system of an open reel type VTR as one embodiment of the present invention. The magnetic tape 2 wound around the supply-side reel 1 is a roller post 3,
Supply side tension arm 4, fixed posts 5, 7, full width erasing head 6, movable guide posts 8, 10, rotating drum 9, fixed heads 11, 16, longitudinal track recording / reproducing heads 12, 13, 14, 15, capstan 17 , The pinch roller 18, the timer roller 19, the take-up side tension arm 20, and the roller post 21 and are loaded on the take-up side reel 22.

A recording / reproducing mode in which a change in tape tension is a particular problem will be described. In the recording / playback mode, the magnetic tape loaded as described above
It is sandwiched between the capstan 17 and the pinch roller 18 and driven by the rotation of the capstan 17.

At this time, in order to perform recording on the magnetic tape 2 or reproduction from the magnetic tape 2 stably, it is necessary that the tension on the rotary drum 9 is constant. Therefore, the tape tension is controlled by keeping the output value of the potentiometer 24 attached to the rotary shaft of the tension arm 4 constant. The tension set value at this time is set as follows in order to eliminate the influence of the tape friction coefficient and the like.

The load current of the capstan motor 19 is detected by the current detector 28, and the tension set value generator 2
9 is input. In the tension set value generator 29, the load current I _R of the capstan motor 19 when a desired tape tension is obtained on the rotary drum 9 is preset, and this value and the detected value I from the current detector 28 are set. comparing _B, and varying the tension setting value by the difference value I _E = I _R -I _B, the tape tension error detector 30
It is input as the standard setting value of. The tape tension error detector 30 compares the tension set value with the output value of the supply-side potentiometer 24, sends the error to the supply-side reel motor drive amplifier 31, and controls the supply-side reel motor 27. To do.

Next, each detected value and its control method will be described. First, FIG. 2 shows the relationship between the tape tension at the tension arm 4 and the tape tension at the output side of the rotary drum 9. (Here, the relationship with the tape tension on the output side, not the tape tension on the rotary drum 9, is shown because the tension on the output side of the rotary drum 9 can be easily measured and confirmed with a commercially available tension measuring instrument. Since there is a correlation with the tension on the rotating drum 9, controlling the tape tension on the output side to be constant is equivalent to controlling the tape tension on the drum to be constant. Then, the tension control on the drum is treated as the tension control on the drum output side.)

It is shown that, depending on the type of tape, even if the tape tension at the tension arm portion is the same, the tape tension at the drum output side is different. In other words, even if the tension of the tension arm portion is controlled to be constant and the tension there is set to Ti1,
The tension on the drum output side is different like To3, To1, To2, and it can be seen that it is an unstable element for the recording / reproducing characteristics.

Since the original purpose of tension control is to make the tape tension on the drum output side constant, it is necessary to keep the value on the vertical axis constant in FIG. In other words, in order to obtain the desired tension To1, the tension at the tension arm is set to Ti for TAPE A.
2, it can be seen that it is necessary to switch Ti1 for TAPE B and Ti3 for TAPE C.

Next, FIG. 3 shows that a change in tension on the drum output side is correlated with a change in load current of the capstan motor. Therefore, if the tension is controlled so that the load current of the capstan motor becomes IC1 (I _R above) regardless of the type of tape, the tension on the drum output side becomes To1 and stable recording and reproduction can be performed. it can.

Further, it is considered that the tape friction coefficient is almost constant irrespective of the position if the tape is the same, and the change with time of the friction coefficient of the running system is negligible in a short time when the same tape is loaded. To be Therefore, if a memory circuit is provided in the tension set value generator 29, for example, if the tension set value correction value is stored in memory by the capstan motor load current in the first recording / reproducing mode after tape loading, It is also possible to complete the detection mode once by controlling the value until the tape is replaced.

Further, when the capstan current is detected and taken into the CPU 33 by the A / D converter 32, when the detected current value becomes the normal tape running system, the load current and the set value which cannot be obtained by the magnetic tape. Protects the tape from damage by generating an alarm or shutting down the system by the system controller 34. If the capstan motor load current does not decrease even if the tape tension setting value is lowered, it is judged that sticking has occurred in a part of the running system and an alarm is generated or the system is shut down as described above. Prevents tape damage.

[0018]

According to the present invention, the load current of the capstan motor for driving the magnetic tape is detected, and the tape tension set value is changed according to the load current. Since the tape tension change above can be corrected and made constant, stable recording and reproduction can be performed.

[Brief description of drawings]

FIG. 1 is an open reel type VTR according to an embodiment of the present invention.
It is a schematic block diagram of a traveling system.

FIG. 2 is a characteristic diagram showing a relationship between a tension arm tension and a drum exit side tension.

FIG. 3 is a characteristic diagram showing a relationship between a drum output side tension and a capstan motor current.

[Explanation of symbols]

4 Supply side tension arm 9 rotating drum 17 Capstan 18 pinch rollers 24 Supply side potentiometer 28 Current detector 29 Tension set value generator 30 Tape tension error detector 31 Supply side reel motor drive amplifier 27 Supply side Lee motor

Claims (4)

[Claims] 1. A reel for winding one magnetic tape, a tension control loop for detecting a tape tension, and controlling a reel motor so that the detected value becomes a preset value, and the magnetic tape. A magnetic recording / reproducing apparatus having a capstan motor for running, detecting a load current of the capstan motor, feeding back an output corresponding to the detected value to the tape tension control means, and varying a set value. A magnetic recording / reproducing apparatus characterized in that the tape tension on the drum is controlled to be constant according to. 2. The coefficient of friction of the loaded magnetic tape,
In order to correct the difference in the tape tension on the drum due to the difference in the friction coefficient of the running system of the magnetic recording / reproducing apparatus, the load current of the capstan motor in the first recording / reproducing mode after loading the tape causes the difference in the friction coefficient. The feature is that the tape tension on the drum is controlled to be constant by calculating the tension correction value, storing the tension correction value in memory until the tape is replaced, and varying the tension setting value based on that value. And a magnetic recording and reproducing device. 3. The load current of the capstan motor is detected, and the tape tension set value is changed based on the detected load current,
In the control method to control the tape tension on the drum at a constant level, a normal tape running system, a load current not possible with magnetic tape, and an alarm generated when the set value is reached or the system is down and high tension due to sticking etc. A magnetic recording / reproducing apparatus having a function of preventing tape damage due to tape slack when an abnormality or an abnormality in the tension control system occurs. 4. The load current of the capstan motor is detected, and the tape tension set value is changed based on the detected load current,
When it is detected that the load current of the capstan motor is higher than the reference value in the control method of controlling the tape tension on the drum to be constant, the tape tension setting value is lowered based on this result, but the load current of the capstan motor is decreased. The magnetic recording / reproducing device is characterized by having a function to prevent tape damage when an alarm is generated or the system goes down when it is determined that sticking has occurred in a part of the running system when the temperature does not fall.