JPH0487588A - Tension servo device - Google Patents

Abstract

PURPOSE:To improve control accuracy and miniaturize it by accessing the data to offset torque ripple and changing over the gain of motor drive controls, and compensating the change of winding diameter by a winding diameter compensating means, and electrically generating a rotational angle to the reference signal of rotation by a rotational angle generator. CONSTITUTION:The torque control data, which are accessed from a torque data control data storage means 8 by a rotational angel detection means 7, changes over the gain of motor driving controls 6. Therefore, the torque ripple of high frequency is suppressed. Moreover, the application voltage Vm, which is proportional to the rotation cycle gotten by a winding diameter compensating means 10, is made in motor driving controls 6, and is supplied to a motor 4, and the tension ripple by the winding change is suppressed without using a tension detector. Furthermore, by a rotational angle generator 9, a rotational angle occurs electrically to the reference signal to the reference signal of rotation. Therefore, the tension servo device can be made simple in structure, and miniaturized.

Description

[Detailed Description of the Invention] [Summary] The present invention comprises a rotation detecting means coupled to the shaft of a supply reel;
Torque control data for canceling torque fluctuations using the rotation angle of the electric motor as a parameter is stored, the torque control data is accessed using the rotation angle with the rotation detection means as an address, and the gain of the electric motor drive control section is adjusted. An output of the rotation angle detection means and a winding diameter correction means that adjusts the motor driving section so as to provide the electric motor with a torque proportional to the rotation period determined by the switching torque control data storage means and the rotation detection means. A tension control device equipped with a rotation angle generating section that divides the time of one cycle of a signal into a plurality of time intervals and generates signals of a plurality of rotation angles, and is capable of improving control accuracy and improving economic efficiency through miniaturization. .

[Industrial application field]

The present invention relates to a tension control device that controls the tension of a magnetic tape at a constant level by applying back torque to a supply reel during signal recording/reproduction in a magnetic tape device.

The present invention refers to torque ripple control of a supply reel motor in the case of correcting tension changes caused by changes in supply reel diameter without using a tension detector.

[Conventional technology]

FIG. 11 is a diagram showing a conventional tension servo device. It should be noted that similar components are represented by the same reference numerals or symbols throughout the plan. The configuration of this figure will be explained. This figure shows a magnetic tape 1 on which electrical symbols are recorded/reproduced in a magnetic tape device, a supply reel 2 that supplies the magnetic tape 1, and a tension post that is pressed against the magnetic tape 1 to express the tension on the magnetic tape as a voltage signal. a tension detector 3 that converts the voltage into a tension detector 3, and a DC motor 4 whose shaft is connected to the same shaft as the supply reel and which applies a back torque to the supply reel 2 in a direction opposite to the direction in which the supply reel 2 rotates.
The output signal of the adder 5 which inverts and adds the voltage signal V from the tension detector 3 to the reference voltage signal Vr is power amplified and sent to the DC motor 4 to generate back torque. A DC motor drive unit 10 that supplies
a reel rotation detection sensor 11 whose shaft is connected to the same shaft as the supply reel 2; a capstan 12 which serves as a feeder for running the magnetic tape 1 at a constant speed;
It includes a known tension servo device consisting of a pinch roller 13 which is a rotating roller that presses the magnetic tape 1 onto the capstan 12 and runs it, and a magnetic head 14 that records/reproduces the magnetic tape 1. The reel rotation detection sensor 1
There are various types of 1. For example, there are those that have multiple holes around the disk and detect the rotation angle using a light emitting/receiving part, those that are reflective, and those that use magnetism, and the tape is not cut. It is also used to detect abnormalities such as whether loading is normal or not, and to control the tape speed by applying servo to the tape counter and FF/R8111.

Next, the operation will be explained. Since the magnetic tape is supplied from the supply reel, the diameter (r) of the magnetic tape wound on the supply reel decreases as the tape is pulled out. Generally, if the tension of magnetic tape 1 is F, back torque T
The relationship T=rXF holds true. Tension F of the magnetic tape 1 is formed by fixing the magnetic tape 1 between a capstan 12 and a pinch roller 13. Therefore, as the diameter r of the magnetic tape decreases, it is necessary to decrease the back torque T in order to keep the tension F constant. This is because when ΔVl=Vr-Vt=00, when only r becomes smaller, the tension F increases. Therefore, the tension voltage V from the tension detector 3 increases and becomes ΔV+=Vr Vt<0, so that the armature current of the DC motor 4 decreases, and this back torque T decreases.

In this manner, the tension servo device performs recording/reproduction on the magnetic head 14 through feedback control to keep the tension of the magnetic tape constant.

[Problem to be solved by the invention]

However, the DC motor 4 of the conventional tension servo device has a plurality of magnetic poles, and if the number of magnetic poles is large, no particular problem will occur, but if the number of magnetic poles is reduced to reduce economic costs, the torque ripple that synchronizes with the rotation speed will occur. arises on its own. This torque ripple has a higher frequency than the conventional change in the winding diameter of the magnetic tape, and the effect of suppressing the detected fluctuation is significantly reduced. Because supply reel 2
This is because the DC motor 4 and the like have a moment of inertia and cannot generate back torque in response to high frequency torque ripple. Therefore, the tension F of the magnetic tape 1 fluctuates in high frequency components, and the magnetic head 14
There is a problem in that recording/reproduction cannot be performed normally, which poses an obstacle to the need to improve economic efficiency by downsizing the tension servo device.

Further, although the tension detector is indispensable for feedback of the tension strength, its presence has been an obstacle to miniaturization of the device. Furthermore, as a step toward solving the above-mentioned problem, when trying to accurately measure this high-frequency torque ripple in response to the rotation angle of the supply reel 2, the reel rotation detection sensor 11 has a large disk diameter. Another problem arises in that the wall thickness also increases.

Therefore, in view of the above problems, it is an object of the present invention to provide a tension servo device capable of feedback controlling high frequency tension fluctuations of a magnetic tape.

[Means to solve the problem]

FIG. 1 is a diagram showing the basic configuration of the present invention. This figure shows that in order to solve the above problem, the tension control device includes a rotation angle detection means 7, a torque control data storage means 8,
It has a winding diameter correction means 10.

The torque control data storage means 8 stores torque control data for canceling torque fluctuations using the rotation angle θ of the electric motor 4 as a parameter. The winding diameter correction means 10 determines the rotation period of the supply reel 2 from the rotation angle θ determined by the rotation means 7, and calculates a torque proportional to the magnitude of the rotation period. Furthermore, the rotation angle detection unit 7 divides the time required for one rotation of the electric motor 4 into a plurality of equal time intervals, and generates signals of a plurality of rotation angles (θ1, θ2, . . . , θNI). 9.

[For production]

In FIG. 1, according to the tension servo device of the present invention, torque control data accessed from the torque control data storage means 8 by the rotation angle detection means 7 switches the gain of the motor drive control section 6. Therefore, high frequency torque ripple is controlled. Further, an applied voltage V proportional to the rotation period obtained by the winding diameter correction means 10,
is formed by the motor drive control section 6 and supplied to the motor 4,
Tension fluctuations due to changes in winding diameter are controlled without using a tension detector as in the past. Further, the rotation angle generating section 9 electrically generates a rotation angle with respect to a rotation reference signal. Therefore, the tension servo device can be made simple in structure and downsized.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a tension servo device according to a first embodiment of the present invention. The configuration of this figure will be explained. This figure shows the rotation angle detection means 7 provided on the shaft of the supply reel 2 that supplies the magnetic tape 1 recorded/reproduced by the magnetic helad 14 via the capstan 12 and the pinch roller 13, and the rotation angle detection means 7 provided on the shaft of the supply reel 2 that supplies the magnetic tape 1 to be recorded/reproduced by the magnetic helad 14, Torque control data for canceling torque fluctuations as a parameter is stored, and the torque control data is accessed using the rotation angle θ of the rotation detecting means 7 as an address to switch the gain of the motor drive control section 6. The rotation period of the supply reel (2) is determined from the control data storage means 8 and the rotation angle (θ) determined by the rotation detection means (7), and a torque proportional to the magnitude of the rotation period is applied to the electric motor 4. a winding diameter correcting means (10) for adjusting the motor drive control section (6) so as to give the motor drive control section (6); D connected
/A (Digital/Analog) converter 25
including.

Next, the rotation angle detection means 7 includes a reel rotation detection sensor 11 and comparators 16 and 17. FIG. 3 is a diagram showing the rotation angle of the reel rotation detection sensor.

Although the reel rotation detection sensor 11 shown in this figure is a transmission type photointerrupter, it may be a reflection type photointerrupter.

The reel rotation detection sensor 11 of the transmission type photointerrupter includes a disk 11-1 attached to the shaft of the supply reel 2, and a plurality of holes 11 provided at equal intervals around the disk 11-1.
−2 (i=1, 2,..., n) and the disk 1
A magnet 11-3 provided on the convex portion of the outer periphery of the magnet 11-1, a light emitting/light receiving section 11-4 that detects the edge of the hole 11-2, and a magnet 11-3 that is rotated by the rotation of the disk 11-1. It has a magnetoresistive element MRII-5 whose resistance value changes depending on the magnetic field when it passes through the most recent value. Since one hole in the light emitting/light receiving section 11-4 has two edges, it detects 2n edges. Since these edges are equally spaced, the rotation angle θ of the k-th edge is expressed as θ=(2π/2n)Xk.

Further, in the rotation angle detecting means 7, a comparator 16 is connected to the light emitting/light receiving section 11-4 and passes a pulse of a predetermined level, and a comparator 17 is connected to the magnetoresistive element MRII.
-5 and passes a pulse of a predetermined level.

Next, the torque control data storage means 8 uses the comparator 1 to count the rotation angle signal of the reel rotation detection sensor 11.
A counter unit 21 is connected to the comparator 17 to clear the count of the address counter unit 21 by inputting a timing signal representing the rotation angle reference of the reel rotation detection sensor 11, and a mono multi-by break 22, A variable resistor Rv connected to the mono multivibrator 22 and delaying the output signal with respect to the human input signal.
23 and pre-measured torque control data for offsetting control of torque fluctuations using the rotation angle θ of the electric motor 4 as a parameter, and calculates the torque using the count representing the rotation angle θ of the address counter section 21 as an address. ROM (Read Only Memory) for accessing control data
y) Contains 24.

FIG. 4 is a diagram showing gain switching of the motor drive control section. The motor drive control section 6 includes a non-inverting amplifying section 41 which inputs the difference signal from the differential amplifying section 5 to a non-inverting terminal, and a feedback section connected to the output of the non-inverting amplifying section 41 and the other connected to its inverting terminal. a resistor 42 (Rf), a gain adjustment section 43 connected to the inverting terminal of the non-inverting amplifying section 41 and the other end being grounded, and a gain adjusting section 43 whose base is connected to the output of the non-inverting amplifying section 41 via a resistor Rt; a transistor 44 whose collector is connected to the power supply and whose emitter is connected to the motor 4; Here, the gain adjustment section 43 includes a plurality of resistors R1□, R12...+RIh connected in parallel, and switch means sw connected in series to each resistor.
, s w2° . . . , SW, and the switching means is opened and closed by the ROM 24. SW+
The gain G of the non-inverting amplifying section 41 when only one is closed and the other is open is c=i+Rf/R++. ROM 24
Since the switch means can be opened and closed in any combination based on the data, the value of the gain G can be controlled arbitrarily. Therefore, the transistor 44 can supply a current to the motor 4 to generate torque based on the value of the gain G.

Next, the operation of the torque control data storage means 8 will be explained. FIG. 5 is a diagram showing torque ripple control according to the present invention. This figure (a) shows a timing signal of the magnetoresistive element MRII-5, which is generated every time the disk 11-1 of the reel rotation detection sensor 11 rotates once. This figure (b) shows the rotation angle signal of the light emitting/light receiving section 11-40. This figure (c) is a diagram showing the torque ripple before the control, which has been measured in advance. The timing signal clears the address counter 21 that counts the rotation angle signal of the light emitting/light receiving section, and determines the reference value of the rotation angle. In this figure, the variable resistance RV of the mono multi-vibration brake 22 is adjusted so that the torque ripple that repeats a plurality of times in one rotation before control becomes a trough when the timing signal is generated. This figure (d) shows the torque control data stored in the ROM 24, specifically, each resistance R++ + R12+ of the gain adjustment section 43 of the motor drive control section 6.
This is switching data of R131...+Rln, and indicates the gain of the motor drive control unit 6 that should cancel torque ripple with respect to the rotation angle θ.

FIG. 4(e) shows the output voltage of the non-inverting amplifier 41 that drives the transistor 44 in FIG. Curve A in this figure is the output voltage according to this embodiment. Curve B is the output voltage of the conventional differential amplifier section 5. This figure (f) shows the output voltage V of the tension detector 3 according to the present invention.

This is a diagram. In this way, fluctuations in the torque ripple of the electric motor 4 can be eliminated and the contact between the magnetic tape 1 and the magnetic head 14 can be optimized.

Next, the winding diameter correcting means performs the following calculation in order to control the tension by changing the radius of the winding on the supply reel 2 using the signal from the rotation detecting means 7.

Further, the torque T has the following relationship with the tension F.

T=FXR (3) where R (Cm) indicates the radius of the tape 1 on the supply reel 2.

From the above equations (2) and (3), here ■: Applied voltage of the electric motor 4 (V) F: Tension of the magnetic tape 1 (g) U: Tape speed (cm/5ec) Z: Per 201 revolutions of the supply reel Number of pulses generated, g: Conductance of the motor 4 (m h o ) KT: Motor torque constant (gem/A) T. : Rotation period (S) of the supply reel 2 In the above equation (1), the applied voltage v of the electric motor 4
,.

is proportional to the rotation period of the supply reel 2.

The process of (1) above is shown below. The torque T(g,) generated by the electric motor 4 has the following relationship with the applied voltage V.

T = g-KrV, (2) On the other hand, the rotation speed N (rps) of the supply reel 2 is 1 of the supply reel 2.
The number of pulses generated per rotation Z and the period Tpc have the following relationship.

Further, the rotation speed N has the following relationship with the radius R and speed U of the magnetic tape 1.

Substituting this equation (7) into the above equation (4) from the above equations (5) and (6) yields the above equation (1).

Transforming equation (1) above, we get In this equation, 2πg-Kt/U2 is constant.

As R becomes smaller, it becomes smaller. Therefore, V is TFG
If the tension F is made to change in proportion to , the tension F becomes constant. The torque control data storage means 8 winding diameter correction means l01 D/A converter 25 in FIG.
It is also possible to configure it by providing it inside the tank.

FIG. 6 is a diagram showing the configuration of the winding diameter correcting means in FIG. 2. This figure shows the rotation period of the supply reel TF from the pulse from the rotation detection means 7 in order to calculate the applied voltage V.
It includes a period calculation unit 51 that calculates G, a constant storage unit 52 that stores a constant a, and an applied voltage calculation unit 53 that calculates the applied voltage V by calculating V, =aT.

FIG. 7 is a diagram showing tension changes when no winding diameter correction is performed. This figure shows that the tension F at the start is 12
The ratio at the end after 0 minutes is approximately double.

When the winding diameter correction means 10 according to this embodiment is used, this ratio becomes almost constant.

Therefore, the back torque that changes depending on the winding diameter can be controlled without using a conventional tension detector, and the tension control device can be made smaller.

Further, by using FIG. 2, the torque control data storage means 8, and the winding diameter correction means 10, it is possible to simultaneously control the torque ripple and the winding diameter change.

FIG. 8 is a diagram showing a tension control device according to a second embodiment of the present invention. The component in this figure that differs from the first embodiment is the rotation angle detection means 7. The rotation angle detection means 7 detects a disc 18-L supplied to the shaft of the supply reel.
A magnet 18-2 provided on a convex portion on the outer periphery of the magnet 1
The reel rotation detection sensor 18 consists of a magnetoresistive element MR18-3 that detects the magnetic field of 8-2, and the magnetoresistive element M
Of the signals from R18-3, only those above a certain level are passed, and the output is stored in the torque control data storage means 8.
A comparator 17 connected to the mono-multivibrator 23 and a rotation angle generating section 9 connected to the comparator 17 and generating a rotation angle to be output to the counter section.

FIG. 9 is a diagram showing a rotation angle generating section according to a second embodiment of the present invention. In this figure, the rotation angle generating section 9 is connected to the comparator 17 of the rotation angle detection means 7, manually counts the reference clock CP obtained by dividing the clock signal of the crystal oscillator, and clears the count using the output signal of the comparator 17. latches the count data of the counter A32 that has been shifted downward by 1/N (=1/2°: n is the shift amount), and this latched data is cleared by the output signal of the comparator 17. a latch unit 3, a counter B35 that inputs a reference clock and counts;
The digital comparator 36 compares the count of the counter B35 with the latch count of the latch unit 34 and outputs a pulse to the timing controller 26 if they match, thereby clearing the count of the counter B35.

FIG. 10 is a diagram showing a time chart of the rotation angle generator in FIG. 9. This figure (a) shows a clock pulse. This figure (b) shows the signal from the comparator 17. This is the signal when the number of holes in the disk shown in Figure 3 is eliminated,
That is, one rotation of the supply reel 2 generates one pulse. This is a pulse signal when the rising edge of the detector 11 is detected.

The figure (C) shows the count value obtained by counting the reference clock by the counter A32, which is cleared by the pulse signal of the comparator 17, and the count value immediately before being cleared is set as α. Since the magnetic tape wound on the supply reel 2 is very thin, there is no problem in accuracy in generating the rotation angle described later even if the immediately preceding count value is used. This figure (d) shows that the set value d of the latch unit 34, for example, the value α/4, is set and held until the next signal from the comparator 17 arrives. In the figure (d), e indicates the count value of the counter B35. In the figure (e), when the count value e of the counter B35 reaches the value α/4, a pulse signal is generated and the count value of the counter B35 is cleared. In this way, the period of the pulse b of the comparator 17 is reduced to 1/
N, that is, the time required for one rotation is divided into a plurality of equal time intervals, and a plurality of rotation angles θ11. θ1□,...,θ
A virtual rotation angle signal of NN can be output. In this way, the reel rotation detector I8 does not require a large number of holes or reflective parts as in the prior art, so it can be made smaller.

〔Effect of the invention〕

As described in detail above, according to the present invention, data for offsetting torque fluctuations is accessed from the torque control data storage means in accordance with the rotation angle of the rotation angle detection unit provided on the shaft of the supply reel, and the electric motor Since the gain of the drive control section is switched, high-frequency torque fluctuations can be controlled, and changes in winding can be corrected by the winding diameter correction means, and furthermore, the rotation angle generator can electrically adjust the rotation angle with respect to the rotation reference signal. Since this is made to occur, it is expected that the control accuracy of the tension control device will be improved and the economical efficiency will be improved due to miniaturization.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle configuration of the present invention, Fig. 2 is a diagram showing a tension servo device according to the first embodiment of the invention, and Fig. 3 is a diagram showing the rotation angle of the reel rotation detection sensor in Fig. 2. FIG. 4 is a diagram showing gain switching of the motor drive control section; FIG. 5 is a diagram showing torque ripple control according to the present invention; FIG. 6 is a diagram showing the configuration of the winding diameter correction means in FIG. 2. , Figure 7 is a diagram showing the tension change when the winding diameter is not corrected, Figure 81! I is a diagram showing a tension servo device according to a second embodiment of the present invention, No. 91! 1 is a diagram showing the rotation angle generating section in FIG. 8, FIG. 10 is a time chart of the rotation angle generating section in FIG. 9, and FIG. 11 is a diagram showing a conventional tension servo device. In the figure, 1...magnetic tape, 2...supply reel, 4...
...Electric motor, 5. Differential amplifier, 6. Motor drive control section, 7. Rotation detection means, 8. Torque control data storage means, 9. Rotation generation section, 10. ... Winding diameter correction means.

Claims (1)

[Claims] 1. A supply reel (2) that supplies the tape (1), an electric motor (4) coaxially connected to the supply reel (2), and adjustment of back torque of the electric motor (4). A tension control device comprising: a motor drive control section (6), and a rotation detection means (7) coupled to the supply reel (2);
and storing torque control data for offsetting control of torque fluctuation using the rotation angle (θ) of the electric motor (4) as a parameter, and detecting the torque using the rotation angle (θ) of the rotation detection means (7) as an address. A torque control data storage means (8) that accesses control data and switches the gain of the motor drive control section (6), and a rotation angle (θ) determined by the rotation detection means (7) when feeding the tape at a constant speed. ) for determining the rotation period of the supply reel (2), and adjusting the motor drive section (6) so as to apply a torque proportional to the rotation period to the motor (4).
) A tension control device comprising: 2. The time for one rotation of the rotation angle detection means (7) is divided into a plurality of equal time intervals to detect a plurality of rotation angles (θ_1, θ_2).
, ..., θ_N).
) The tension control device according to claim 1.