JPS6337882A - Positioning control circuit for magnetic tape device - Google Patents

Abstract

PURPOSE:To facilitate start control and to reduce the access time by applying feedback control to a reel motor so as to set the difference between a target stop distance and a running distance of a magnetic tape after the generation of a stop instruction to zero. CONSTITUTION:A tape radius RF of a supply reel outputted from a computing element 10 is calculated (11), and the running distance LF of the magnetic tape per pulse outputted from a tachometer 3 is obtained. The distance LF and a count value X of a position detector 7 are inputted to a stop distance error detector 12 to obtain a distance error DELTAL from the distance LF. The error DELTAL is given to a current computing element 15 via a filter 13 and a position error current computing element 14. Further, a computing element 18 obtains an outer circumferential velocity VF of the supply reel from the output count value of a speed detector 6, gives the result to a speed error current calculator 20 and sends the error signal of the target value of the speed VF to the computing element 15. The computing element 15 receives the output of the computing elements, 14, 20 and the output of a supply reel radius coefficient table 21 to apply feedback control to the motor 1 as the error DELTAL=0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning control circuit for a magnetic tape device, and more particularly to a positioning control circuit for a magnetic tape device suitable for always keeping the stopping distance of a magnetic tape constant. .

[Conventional technology]

In the prior art, magnetic tape stopping and positioning control was performed as follows. That is, upon generation of a stop command, a constant current corresponding to the reel radius is applied to the motor in a direction opposite to the running direction.

As a result, the running direction of the magnetic tape is rapidly reversed.
Drive in the opposite direction. Next, positioning control is performed with the position where the traveling direction is reversed as the target stop position.

As a prior art related to the above-mentioned prior art, the invention described in Japanese Patent Application Laid-Open No. 53-144307 is known.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, stop and position control is performed regardless of the radius of the tape around which the magnetic tape is wound on the reel. For this reason, due to changes in the tape radius, variations in the loop gain of the control system, etc., a situation has arisen in which the amount of tape required to stop, that is, the stopping position varies.

Therefore, in position control in conventional technology, consideration is not given to always stopping and positioning at a constant distance, and
There are the following problems when starting the magnetic tape after positioning. In other words, when writing data after starting up the magnetic tape, it is necessary to create a gap called IBG between the field where data has already been written and the field where new data is to be written, but it is necessary to create a gap called IBG at the boundary between the field where data has already been written and the field where new data is to be written. Since this is not constant, special consideration must be given to magnetic tape start-up control and gap control.

In other words, after the magnetic tape starts running at a constant speed, G and data are written from the gap, but since the above-mentioned stop position is not constant, the start control and gap need to be controlled.

Such a situation requires a large amount of access time and becomes an obstacle to writing data at high speed.

The present invention was developed in view of the above-mentioned problems of the prior art, and it allows the magnetic tape to always stop at a constant stopping distance, regardless of changes in the tape radius or fluctuations in the loop gain of the control system, so that data can be transferred at high speed. The purpose of the present invention is to provide a positioning control circuit for a magnetic tape device that enables writing to a magnetic tape device.

[Means for solving problems]

The positioning control circuit for the magnetic tape device of the present invention includes a first means for determining the tape radius of the magnetic tape wound on the reel when a stop command is issued, and a second means for determining the rotation angle of the reel after the stop command is issued. And the above 1. A third means determines the running distance of the magnetic tape after the stop command is issued based on the tape radius and rotation angle determined by the second means, and feedback-controls the reel motor so that the difference from the target stopping distance becomes zero. It is characterized by having the means.

[Effect]

According to the present invention, the reel motor is feedback-controlled in accordance with the radius of the tape wound on the reel, and the reel motor is always driven by a target stopping distance to be stopped and positioned. Therefore, it is possible to stop at a constant distance regardless of changes in the reel radius, fluctuations in the loop gain of the control system, etc.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the accompanying drawings.

The accompanying drawings are block diagrams illustrating one embodiment of the present invention.

As shown in the figure, digital tachometers 3 and 4 are installed on the shafts of the supply reel motor 1 and the take-up reel motor 2.
is attached, and the tachometer 4 of the take-up reel motor 2 is 1
One pulse is generated by rotation, and the tachometer 3 of the supply reel motor 1 generates one pulse at a sufficiently smaller angle than that on the winding side.

Here, the pulses output from the tachometer 4 on the winding side are sent to the radius detector 5, and the pulses output from the tachometer 3 on the supply reel side are sent to the radius detector 5.
The pulses output from the radius detector 5 and speed detector 6
and is sent to the position detector 7.

The radius detector 5 counts how many pulses are generated from the tachometer 3 on the supply side within one cycle of pulses output from the tachometer 4 on the winding side, and calculates the count value N.
A digital signal processor with a built-in arithmetic unit (
(hereinafter abbreviated as DSP) 8.

The speed detector 6 counts clock pulses with a period T output from the oscillator 9 during one pulse period output from the tachometer 3 on the supply reel side, and transfers the count value M at that time to the DSP 8.

The position detector 7 is composed of a counter, and a count value is set to a reference value 11011 upon generation of a stop command. Then, depending on the running direction of the magnetic tape, the pulses output from the tachometer 3 on the supply reel side are counted up or down, and the count value
0 for example.

The count is incremented from when the stop command is output until the running direction of the magnetic tape is reversed, and after the running direction is reversed, it is counted down.

DS
It is output to the tension current calculator 28 in the PB.

The DSP 8 controls the supply roll motor 1 and the take-up roll motor 2 as follows in response to the errors in the count values N, M, X and tension 1 described above.

The arithmetic unit 10 in the supply reel motor control DSPa calculates and outputs the tape radius RF of the supply reel according to the following equation (1).

However, RMAX: Maximum reel radius RMIN:
Minimum reel radius NF: Number of pulses output from the tachometer 3 per revolution of the supply reel In equation (1), NFI RMIN is a value unique to the device, and RNA is the number of pulses output from the tachometer 3 for each revolution of the supply reel.
OT (Beginning of The Tape)
) The positioning is sometimes a value determined by the following equation (2).

The tape radius RF of the supply reel thus determined is input into the supply reel radius coefficient table 21 on the one hand;
A coefficient corresponding to the tape radius RF is read out and input to the supply reel motor current calculator 15.

On the other hand, the tape radius RF of the supply reel output from the computing unit 10 is input to the computing unit 11.
Then, the travel distance LF of the magnetic tape per one pulse output from the tachometer 3 is determined according to the following equation (3).

The travel distance LF described above and the count value X output from the position detector 7 are input to the stopping distance error detector 12, where the distance error ΔL from the constant target stopping distance is calculated according to the following equation (4). is required.

A L=L-X-LF -- (4) The above distance error ΔL is input to the supply reel current calculator 15 via the position control filter 13 and the position error current calculator 14.

Further, the calculation unit 18 in the DSPS receives the count value M output from the speed detector 6, and receives the count value M output from the speed detector 6, and receives the outer peripheral speed v of the supply reel.
F is determined and output according to the following equation (5).

2 ・π VF= RF・・・・・・・
...(5)-T-NF The outer peripheral speed LF is transmitted through the speed control filter 19,
A signal is input to the speed error current calculator 20, and a signal corresponding to the error of the outer peripheral speed vF from the target value is input to the flow calculator 15 for the supply reel.

The supply reel current calculator I5 receives the output of the position error current calculator 14, the output of the speed error current calculator 20, the coefficient value from the supply reel radius coefficient table 21, and the output of the tension current calculator 28. , the AD converter 16 and the supply reel drive circuit 17 so that the distance error ΔL=O.
The supply reel motor 1 is controlled via.

Control of the take-up reel motor The take-up reel motor 2 is controlled in the same manner as the supply reel motor 1 described above. That is, the calculation ri22 in the DSPB calculates and outputs the tape radius R'F of the take-up reel. From the take-up reel radius coefficient table 29, the coefficient corresponding to the tape radius R'F is 5. +1 removed, grass removal reel motor, ad Ib: and performance''':1.2I:;
The ratio of human power is 2:3. In addition, the take-up reel motor 'J high current calculator 23, like the supply reel motor current calculator 15, receives the output of the position error current calculator 14, the output of the speed error current calculator 20, and the output of the tension current calculator. 28 outputs are input respectively. Therefore, the supply reel motor current calculator 23 receives the above-mentioned outputs and calculates the AD so that the distance error ΔL, which is the output of the stop error detector 12, becomes 0.
The take-up reel motor 2 is controlled via the converter 24 and the take-up reel drive circuit 25.

In the embodiment described above, the tape running distance after the stop command is generated is determined based on the tape radius RF of the supply reel, and the difference from the target stopping distance is zero. The invention is not limited to this, but may be configured such that the tape running distance is determined based on the tape radius R'F of the take-up reel, and the difference from the target stopping distance 11L is calculated.

〔Effect of the invention〕

According to the present invention, it is possible to always perform stopping and positioning at a constant distance from the position where the stop command is generated, regardless of changes in the tape radius, variations in the loop gain of the control system, etc. As a result, startup control and gap control become easier, access time can be shortened, and data can be written at high speed.

[Brief explanation of drawings]

The accompanying drawings are block diagrams illustrating one embodiment of the present invention. 1... Supply reel motor, 2... Take-up reel motor,
3.4... Tachometer, 5... Radius detector, 6...
Speed detector, 7... Position detector, 8... Digital signal processor (DSP), 9... Oscillator, 10
．． 11゜18, 22...Calculator, 12...Stopping distance error detector, 13゜19...Filter, 14...Position error current calculator, 15...Supply reel current calculator, 16
．． 24...AD converter. 17... Supply reel drive circuit, 20... Speed error current calculator, 21... Supply reel radius coefficient table, Z3...
... Take-up reel current calculator, 25... Take-up reel drive circuit, 26... Tension sensor, 27... Tension error detector, 28... Tension current calculator, 2
9... Take-up reel radius coefficient table.

Claims (1)

[Claims] 1. A first means for determining the tape radius of the magnetic tape wound on the reel when a stop command is issued; a second means for determining the rotation angle of the reel after the stop command is issued;
, based on the tape radius and rotation angle determined by the second means, the traveling distance of the magnetic tape after the stop command is issued is determined, and the reel motor is feedback-controlled so that the difference from the target stopping distance becomes zero. A positioning control circuit for a magnetic tape device, characterized in that it is equipped with the means of item 3.