JPS6238551A - Tape reel driving control system - Google Patents

Abstract

PURPOSE:To wind tightly and effectively a tape by decelerating a supply and take-up reel being rotated at the maximum appliable acceleration and repeating accelerating and decelerating operations by prescribed number of times at intervals of a prescribed time. CONSTITUTION:A reel motor control circuit 9 obtains quantities of the magnetic tape, namely, tape radiuses of a supply reel 1 and a take-up reel 6 in accordance with reel tachometers attached coaxially to reel motors 7 and 8 and a ratio of the output pulse number of a tape speed detector 5 and drives reel motors 7 and 8 by currents corresponding to said quantities of the magnetic tape. That is, the control circuit 9 flows the current corresponding to the tape radius of each reel to control the reel so that the peripheral speed for the tape radius of each reel is equal to the speed of the running tape. The accelerating operation at a relatively low acceleration and the decelerating operation at a relatively high acceleration are repeated in order automatically a prescribed number of times at intervals of a proper time during the loading operation before the normal read/write operation. Thus, the interlayer slack of the tape is eliminated to wind tight the tape effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a tape reel drive control system, particularly in a reel-to-reel direct drive magnetic tape device.
This invention relates to a magnetic tape winding control system for stabilizing tape running and protecting magnetic tape.

[Background of the invention]

In oven-reel magnetic tape devices that have a vacuum buffer between a supply reel and a take-up reel, a capstan motor drives a short length of tape separated from a reel with high inertia by the vacuum buffer for writing and reading. Since the tape speed was obtained, precision was not required for reel drive control, but the vacuum column, vacuum pump, etc. took up a large space, making it difficult to downsize. In contrast, reel-to-reel direct drive magnetic tape devices run the magnetic tape without using a capstan.
Since the tape speed for writing and reading is directly controlled by the reel on the take-up side and the supply side, there is no need for tension arms, vacuum columns, etc., and miniaturization is possible. Requires extreme precision. In this case, a particular problem is that if the tape wound on the reel is loose, the tapes will slip due to the inertia of the tape itself. If the tape slips significantly, shinching occurs, in which the magnetic tape bends in a wave-like manner in the gap between layers. moreover,
In a reel-to-reel type device, tape running control necessary for writing and reading is performed by controlling the rotation of the reels on the supply side and take-up side, so even a slight slippage of the tape can cause an abnormality in tape tension or There is a risk of speed abnormality resulting in an emergency stop of the device or a data error.

Loosening of magnetic tape winding occurs due to changes over time or temperature changes during storage of the tape. This method cannot be used to increase the tape winding tension above a certain level in order to prevent the tape from slipping because the tension resistance of ISO standard magnetic tapes varies depending on the type of magnetic tape.

Therefore, as an earlier application, the present applicant proposed a magnetic tape B.
We have proposed a tape tightening method that is performed during the loading operation until positioning at OT (Beginning of Tape) (see Japanese Patent Application No. 58-236115 Mei II). In the method of the above-mentioned prior application, if the tape of the supply reel slips in the acceleration stage m at the start of the loading operation, the amount of tape fed out decreases, but the 5-take-up reel rotates at a predetermined speed. .

The winding speed is relatively faster than the feeding speed.

This is triggered for two reasons: the tape tension becomes abnormally high between both reels, which may damage the tape, and if tape slips during acceleration, this slip will further cause the tape to loosen. I thought of a way to avoid tape slipping as much as possible.

6 and 7 are flowcharts of the structure of the tape tension detector and the winding operation in the magnetic tape winding method of the prior application.

As shown in FIG. 6, the maximum allowable tape tension value is stored in the comparator 15, and the minimum allowable tape tension value is stored in the comparator 16, respectively. If the tension value of the magnetic tape is between the high tension value and the low tension value, it is assumed that there is no loose winding on the supply reel. To detect the tape tension, when one core 12 made of ferrite or the like moves in the direction of the arrow according to the tape tension, the output of the coil 13 changes, and the output is sent to the demodulation circuit 14.
The tape tension signals Ts demodulated by i;* are compared with high tension and low tension by comparators 15 and 16, respectively. If the signal Ts is within the high tension value, no output is output, but if the signal Ts is greater than the high tension value, a tension NG (TNG) signal is output to the reel motor control circuit. The reel motor control circuit, as shown in Figure 7,
First, wrap the tip of the magnetic tape around the take-up reel,
After starting the loading operation, the speed is gradually increased at a torque that is sufficiently lower than the normal starting torque for each tape amount on the supply side and the winding side (step 301).
If the speed is OK, then brake torque is applied to decelerate for a certain period of time (steps 302 and 303).At this time, it is determined whether or not a tension NG signal is output (step 304); if it is, the Apply low acceleration torque again (step 30). If the TNG signal is not output, the above operation is repeated a specified number of times (step 305), and then the tape is rewound, the BOT mark is positioned on the magnetic head, and the loading operation is completed (step 30).
6.307).

In this way, the method of the previous application is a basic method of repeatedly starting and stopping the tape to reduce slack in tape winding. There is no mention of a method for practically maximizing the effect of tightening loose winding.

[Purpose of the invention]

An object of the present invention is to resolve such conventional problems and provide a reel-to-reel direct drive magnetic tape device.
An object of the present invention is to provide a tape reel drive control system capable of effectively tightening loose winding between tape layers.

[Summary of the Invention] In order to achieve the above object, the tape reel drive control system of the present invention provides a reel-to-reel direct drive magnetic tape device that directly drives a magnetic tape between a supply reel and a take-up reel. After loading the reel, the supply and take-up reels are accelerated at an acceleration that is sufficiently lower than the normal acceleration during the winding operation until the beginning of the tape is positioned, and then the supply and take-up reels are rotated at the highest acceleration that can be applied. The feature is that the reel is decelerated and the above acceleration/deceleration operation is repeated a predetermined number of times at predetermined time intervals.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 2 and 3 are diagrams comparing the present invention and the conventional tape winding method.

In FIG. 2(a), the tape speed (rotational speed of the reel) is shown at the top, and the tightness and looseness of the tape are shown at the bottom. Further, FIG. 2(b) shows the tape speed during normal operation. As shown in FIG. 2(b), reel-to-reel direct drive magnetic tape devices often have two types of read/write speeds: high speed drive and low speed drive. In low-speed driving, reading and writing operations are performed at a normal speed a by repeating rising and falling at regular intervals. In this case, an inter-data block gap (IBG) is created at the falling edge.

In high-speed operation, once started, the tape continues running at a speed approximately twice the normal speed a, creating gaps between blocks without stopping the tape. In the conventional winding tightening method, as shown in Figure 2 (a), when the reel is accelerated, a force that tries to return to its original position acts on the tape, which acts in the direction of increasing the looseness of the tape, and when the reel is decelerated, , a force acts on the tape on the supply reel to move it continuously, and acts in the direction of tightening the tape. However, as shown in (a), the magnitude of the acceleration during conventional acceleration is not sufficiently lower than the acceleration a, so the sliding plate in the direction of loosening at the first acceleration part b', that is, the amount of loosening of the winding. becomes larger (bl'),
The amount of slippage in the tightening direction (ex'
) is small. Furthermore, slippage in the tightening direction (cr'
) is reduced by the next slip in the direction of loosening (b2'), so the effect of tightening does not appear. This is because the tightening effect does not appear because it accelerates immediately after decelerating, so there is no time for tightening to take effect sufficiently. This is because there is a shortage of

On the other hand, in Fig. 3, after winding the tape several times around the take-up reel, the acceleration is a fraction of the normal acceleration a.
Accelerate the supply reel to speed ■ by an acceleration value of . In this case, since the acceleration S is a sufficiently small value compared to a, the amount of slippage (bl) in the loosening direction is extremely small. After reaching the speed V, it is then decelerated to the speed O by an acceleration C that is equal to or the maximum possible acceleration fta. If the acceleration is small, the maximum static frictional force between the tape layers that prevents the tape from slipping will be greater than the inertial force that causes the tape to slip, so there will be no increase in loosening of the tape. Furthermore, when decelerating at the maximum acceleration C, the inertia force can easily exceed the maximum static friction force between tape layers with loose winding.

The tape slips. At this time, the tape slips in the direction of tightening the tape on the supply reel, so the tape can be wound tightly. In FIG. 3, after this, the vehicle is not accelerated immediately, but is stopped for a time T, and then the acceleration and deceleration operations using accelerations (i) and (c) are repeated a constant value N times.

During this time T.

Since the slip (ax) in the winding direction is sufficient,
The effect of tightening the winding is extremely large. This predetermined time T is
A certain length or more is required, and in reality, the value of T is set larger than the interval shown in FIG. In the present invention, this cycle of acceleration and deceleration is repeated an appropriate number of times N.

Position the BOT after sufficiently eliminating looseness in the winding. The most important point of the present invention is to provide an appropriate length of stop time T before moving on to the first cycle.

FIG. 1 is a flowchart of a tape winding operation showing an embodiment of the present invention.

First, after starting loading and winding the tape around the first take-up reel, the tape is accelerated to a value that is already a fraction of the normal acceleration a (step 101). Next, the speed V
If it is detected that the acceleration has reached y1. a
or the maximum acceleration C (steps 102, 103). And the speed is 0. That is, after detecting that the tape has stopped (step 104), the tape is stopped for a time T (step 105). After time T has elapsed, the next cycle operation (returning to step 101 to accelerate and then decelerate) is started. This operation is repeated until a prescribed number of times N is reached (step 106). N
After performing acceleration and deceleration operations, position B○T (
Step 107). with this.

Finish loading and move on to read/write operations.

FIG. 4 is an explanatory diagram of the sliding effect between tape layers.

As shown in FIG. 4, it is assumed that there is a loose interlayer between the outer tape layer and the inner tape layer. Jo
Then, the torque Tr that should be transmitted between this layer without the tape slipping is expressed as Tr=Jo-dc,+/dt''-(1), where the applied acceleration is dω/dt.On the other hand, between this layer The torque that can be transmitted is 1 between 1 layer.
The surface pressure per circumference is expressed as the friction coefficient between the POr layers as μ0. When the radius of the layer with loose winding is r, the following relationship exists.

T r =μ. Po-r・・・・・・・・・・・・
-(2) Therefore, from the above equations (1) and (2), the following equation holds true.

lLa Po' r:Jo −dω/d t --
--- (3) As is clear from the above equation (3), since the left side is the torque that can be transmitted without slipping, slipping will occur if the left side is smaller than the right side. That is, the weaker the winding between the layers, the smaller the surface pressure po, or the larger the acceleration Jidω/dt, the following equation holds true and the slippage becomes easier.

μOPO'rkuJOod (J/dt ・=14
) As shown in FIG. 3, in the operation of the present invention, the supply reel is accelerated at a fraction of the normal acceleration and then decelerated at the maximum acceleration C. Therefore, at the time of deceleration, the above equation (
The value of the acceleration dω/dt in 4) becomes an extremely large value, causing slippage. However, at first little acceleration is applied to the inner reel, but then deceleration acceleration is applied to the inner reel, so the outer tape layer is stretched in the direction that maintains the previous speed, that is, the tape near the glabella. , it will slip in the direction of tightening.

FIG. 5 is a schematic diagram of a reel-to-reel direct drive magnetic tape device to which the present invention is applied.

1 is a supply reel, 6 is a take-up reel, 2 is a magnetic tape,
3 is a tape tension detector, 4 is a magnetic head, 5 is a tape speed detector, 7 and 8 are reel motors, and 9 is a reel motor control circuit. The magnetic tape 2 is sent out from the supply reel 1.

Tape tension detector 3. Magnetic head 4. The tape passes through a tape speed detector 5 and is wound onto a take-up reel 6.

The reel motor control circuit 9 includes a reel tachometer mounted coaxially with the reel motor 7.8.

From the ratio of the number of output pulses of the tape speed detector 5, the amount of magnetic tape on the supply reel 1 and the take-up reel 6, that is, the tape radius, is determined, and both reel motors 7.8 are driven with a current corresponding to each amount of magnetic tape. . Thereby, the magnetic tape 2 can be run at a predetermined tape running speed. That is, the control circuit 9 controls the peripheral speed of each reel at the tape radius to be equal to the running tape speed by passing a current according to the tape radius of each reel. In the present invention, during a loading operation before performing such a normal read/write operation, an operation of accelerating at a relatively low acceleration and then decelerating at a relatively high acceleration is performed a predetermined number of times at appropriate time intervals. By automatically repeating the following steps, the slack in the winding between the tapes m can be effectively avoided. The tape wound on a reel tends to loosen the winding between the inner layers due to the passage of time during storage or due to large temperature changes, etc., and tension abnormalities are likely to occur due to the edges between the tape layers. In the present invention, by effectively tightening the tape to prevent it from becoming loose between the eyebrows, which tends to occur under such storage conditions,
It is possible to prevent problems such as tension abnormalities due to tape layering.

〔Effect of the invention〕

As explained above, according to the present invention, the cycle of accelerating the reel at an appropriate acceleration and then decelerating it at predetermined intervals is repeated during the time when the tape is positioned at the tape start mark BOT. Since it is possible to effectively tighten the slack between the tape layers, it is possible to prevent problems such as abnormal tension due to slippage between the tape layers.

[Brief explanation of the drawing]

Fig. 1 is an operational flowchart of a tape reel drive control system showing an embodiment of the present invention, Figs. 2 and 3 are operation comparison diagrams of the present invention and a conventional system, and Fig. 4 is an explanation of the sliding effect between tape layers. 5 is a schematic layout diagram of a tape-to-tape direct drive magnetic tape device to which the present invention is applied, and FIG.
FIG. 7 is an explanatory diagram of a conventional tape winding method. l: supply reel, 2: magnetic tape, 3: tension sensor, 4
: Mi head, 5: Speed sensor, 6: Take-up reel,
7: Supply reel motor, 8: Take-up reel motor, 9:
Control drive circuit.

Claims (1)

[Claims] (1) In a reel-to-reel direct drive magnetic tape device that drives the magnetic tape directly between the supply reel and the take-up reel, the acceleration during normal operation after loading the supply reel and during the loading operation up to positioning the beginning of the tape. After accelerating the supply and take-up reels at a lower acceleration, decelerating the rotating supply and take-up reels at the highest applicable acceleration, and then at a predetermined time interval, repeating the acceleration/deceleration operation at a predetermined rate. A tape reel drive control method that is characterized by repeating the number of times.