JPH0568017B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to magnetic tape drives.

(Prior Art) In a conventional magnetic tape drive device, when the magnetic tape connected to the supply reel motor 1 and the take-up reel motor 8 is run at a constant speed, the cap The stan motor 16 is rotated, and the pinch roller 15 is pressed against the rotating shaft of the capstan motor 16.
The magnetic tape 2 is driven using friction between the magnetic tape 2 and the rotating shaft of the capstan motor 16.

(Problems to be Solved by the Invention) By the way, the following problems have occurred in the case of driving in a conventional magnetic tape drive device.

As mentioned above, since friction is used, the magnetic tape slips and the running speed of the tape changes.

The pressure between the pinch roller and the rotating shaft of the capstan motor (static and impulsive pressure) can damage the tape.

The life of bearings, etc. will be shortened due to the rotation of the capstan motor.

The magnetic tape drive itself is expensive because it requires a mechanism and control circuit for driving the pinch roller.

On the other hand, in order to solve the above problems,
A method of driving the magnetic tape directly by the take-up reel motor 8 shown in FIG. 4 without using a pinch roller or a capstan motor has been considered, but this method lacks accuracy in response speed and tape speed. However, it has not yet been put into practical use.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic tape drive device that does not require pinch rollers and capstan motors and can ensure high and precise drive speeds.

(Means for Solving the Problems) According to the present invention, a magnetic tape drive device includes a supply reel motor for supplying a magnetic tape and a take-up reel motor for winding the magnetic tape. , a speed detection means for detecting the running speed of the magnetic tape, a running phase detection means for detecting the running phase of the magnetic tape, and a magnetic tape speed detection means defined between the supply side reel motor and the take-up side reel motor. A travel path length detection means for detecting the travel path length, a travel path length variable means for changing the travel path length, a speed signal from the speed detection means and a travel path from the travel path length detection means. a first servo control means for receiving the length signal and controlling the take-up reel motor; and a second servo control means for receiving the phase detection signal from the travel phase detection means and controlling the travel path length variable means. and a first servo control means to keep the running speed and running path length of the magnetic tape constant, and a second servo control means to keep the running phase of the magnetic tape constant. A magnetic tape drive device is obtained.

(Example) The present invention will be described below based on Examples.

FIG. 1 is a diagram showing a magnetic tape drive device for a video tape recorder using a rotating head. 1st
Referring to the figure, 1 is a supply side reel motor;
A magnetic tape 2 supplied from a supply reel motor 1 is in contact with rotating rollers 12 and 13 and a tension arm 3. Tension arm 3 is pressed against magnetic tape 2 by the force of a spring (not shown), and usually tension arm 3 is located at a point where the tension of the magnetic tape and the spring force are balanced. A tension servo control section 9 is connected to the tension arm 3. The tension servo control unit 9 controls the magnetic tape 2 by detecting the position of the tension arm 3.
The strength of the tension is detected and the torque of the supply reel motor 1 is controlled to maintain a predetermined tension.

The magnetic tape 2 is wound around a rotating head cylinder of a rotating head 4, and further includes a control track head 5 for detecting the running phase of the magnetic tape 2, a rotating roller 14, and a movable post of a tape running path length variable mechanism 6 to be described later. 61, it is sent to the take-up side reel motor 8 via a rotating roller 7 equipped with a rotation detection plate. A tape running path is defined between the supply reel motor 1 and the take-up reel motor 8.

Here, with reference to FIG. 2, the configuration of the tape running path length variable mechanism 6 will be described. motor 63
An arm 62 is attached to the shaft shaft 63a and extends in a direction perpendicular to the shaft shaft 63a (to the left in the figure). Furthermore, as shown in the diagram, arm 6
A movable post 61 extending upward perpendicularly to the arm 62 is fixed near the upper end of the arm 62 . On the other hand, a potentiometer 64 is connected to the shaft shaft 63b of the motor 63.

Referring to FIG. 3, the magnetic tape 2 is regulated by the rotating roller 14, the movable post 61, and the rotating roller 7, and is moving in the direction of the solid arrow. Now, if the movable post 61 does not move, that is, if the magnetic tape 2 that has passed the position indicated by arrow A at a certain time remains in the same position, it will move to the position indicated by arrow B, for example, after a time ΔT has elapsed. By the way, if the movable post 61 has moved to the position shown by the broken line after the time ΔT has elapsed, the magnetic tape 2 located downstream (on the right side) of the rotating roller 7 will pass the position shown by the arrow B, but on the other hand, the rotating roller 14 The magnetic tape 2 located upstream (left side) will pass through the position indicated by arrow B'. That is, while the magnetic tape 2 downstream of the rotating roller 7 is running at a constant speed, the rotating roller 14
This means that the speed of the magnetic tape 2 upstream of the magnetic tape 2 is accelerated.

Referring again to FIG. 1, control track head 5 detects the running phase of magnetic tape 2 and sends a control track signal to phase servo control section 10. The rotating roller 7 rotates in synchronization with the movement of the magnetic tape 2, and transmits rotation pulses at speed and speed.
It is sent to the travel path length servo control section 11.
The phase servo control section 10 compares the phase of the control track signal with a phase reference signal that specifies the running phase of the magnetic tape given from the outside, and if the phase of the control track signal is delayed, the tape running path length is changed. The tape running path length variable mechanism 6 is controlled as described below to lengthen the running path length, and when the phase of the control track signal is advanced, the tape running path length variable mechanism 6 is controlled to shorten the running path length. , synchronize the control track signal and the phase reference signal.

On the other hand, speed/traveling path length servo control section 1
1 detects the frequency of the rotation pulse, and thereby detects the running speed of the magnetic tape 2. When the running speed of the magnetic tape 2 is slower than a predetermined running speed, the rotational speed of the take-up reel motor 8 is increased.
When the running speed is faster than a predetermined running speed, the take-up reel motor 8 is controlled to lower the rotational speed of the take-up reel motor 8, thereby always keeping the running speed of the magnetic tape 2 constant.

Incidentally, even when the phase servo control section 10 and the speed/path length servo control section 11 are locked, a slight speed deviation may occur in the magnetic tape 2. Therefore, when the magnetic tape is driven for a long time, this speed deviation is integrated, that is, integrating the speed becomes a phase, so the phase of the arm 62 of the variable traveling path length mechanism 6 changes, and the arm 62 changes its phase. Stroke (arm 6
2), and the running path length of the magnetic tape changes.
Therefore, as shown in FIG. 2, the position of the arm 62 is detected by the potentiometer 64, and this result is input to the speed/running path length variable mechanism to increase the running path length of the magnetic tape. At times, the rotation of the take-up reel motor 8 is controlled to be faster, and when the running path length of the magnetic tape becomes shorter, the rotation of the take-up reel motor 8 is controlled to be slowed down, thereby increasing the running path length of the magnetic tape. It is always kept constant.

In this way, by moving the movable post 61 and changing the running path length of the magnetic tape,
The speed of the magnetic tape 2 can be changed.
Furthermore, the running phase of the magnetic tape can be controlled by detecting the running phase of the magnetic tape and servo-controlling the position of the movable post 61 using the phase signal obtained as a result.

By the way, the running path length of the magnetic tape is limited due to the physically limited space. Therefore,
The speed of the magnetic tape 2 cannot be increased or decreased forever by moving the movable post 61. Therefore, it is optimal for the movable post 61 to be located at the center of a predetermined movable range (hereinafter referred to as a stroke). Therefore, it is necessary to control the position of the movable post 61, that is, the length of the tape running path, by controlling the speed of the magnetic tape downstream of the rotating roll 7 so that the movable post 61 is positioned on average near the center of the stroke. It is.

The control (feedback loop) for keeping the length of the magnetic tape running path constant can be performed by simply keeping up with the loose arm that is generated by accumulating slight speed deviations of the magnetic tape.
Needless to say, it is possible to control even a take-up reel motor, which has a large inertia due to the mass of the video tape or turntable and has relatively poor response. Furthermore, since only the arm of the magnetic tape running path length variable mechanism has inertia, it goes without saying that it is possible to respond at high speed.

(Effects of the Invention) As explained above, according to the present invention, the running speed and running path length of the magnetic tape are detected to control the take-up reel motor, and the running phase of the magnetic tape is detected to control the running path length. It controls the variable travel path length mechanism to change the travel path length, so it can always guarantee a high and precise driving speed. Also, pinch rollers and capstan motors are not required.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a magnetic tape drive device according to the present invention, FIG. 2 is a diagram showing a magnetic tape running path length variable mechanism used in the magnetic tape drive device according to the present invention, and FIG. 4 is a diagram for explaining the control of the running path length and speed of the magnetic tape.
The figure shows an example of a conventional magnetic tape drive device. 1... Supply side reel motor, 2... Magnetic tape, 3
...Tension arm, 4... Rotating head, 5... Control track head, 6... Magnetic tape running path length variable mechanism, 7... Rotating roller, 8... Winding side reel motor, 9... Tension servo control section, 10... Phase Servo control section, 11... Speed/traveling path length servo control section, 61... Movable post, 62... Arm, 63... Motor, 64... Potentiometer.

Claims (1)

[Claims] 1. In a magnetic tape drive device comprising a supply reel motor for supplying a magnetic tape and a take-up reel motor for winding the magnetic tape, a speed detection means for detecting the running speed of the magnetic tape; , a running phase detecting means for detecting a running phase of the magnetic tape; and a running path length detecting means for detecting a running path length of the magnetic tape defined between the supply side reel motor and the take-up side reel motor. a traveling path length variable means for changing the traveling path length; and receiving a speed signal from the speed detecting means and a traveling path length signal from the traveling path length detecting means to control the take-up reel motor. and a second servo control means that receives a phase detection signal from the traveling phase detecting means and controls the traveling path length variable means.
The servo control means keeps the running speed and running path length of the magnetic tape constant, and the second servo control means keeps the running phase of the magnetic tape constant. magnetic tape drive.