JP2637609B2 - Tracking control system for magnetic reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to, for example, a video tape recorder (hereinafter, referred to as a video tape recorder).
The present invention relates to a tracking control system in a magnetic reproducing device, such as a magnetic head driving device capable of head position adjustment control used for automatic tracking or the like in a “VTR”.

[Conventional technology]

FIG. 14 is a block diagram of a conventional magnetic head driving device using a bimorph disclosed in Japanese Patent Application Laid-Open No. 52-117107. In the figure, reference numeral 101 denotes a piezoelectric bimorph that bends in accordance with an applied potential, and reference numeral 102 denotes a sensor, which includes a piezoelectric electric generator formed by cutting a part of the bimorph 101. 103 is a high impedance amplifier that hardly applies a load to the sensor 102, 104 is an adder, and adds the output from the high impedance amplifier 103 and the output from a potentiometer 111 described later. 1
05 is a differentiator for differentiating the output from the adder 104, 106 is a low-pass filter, and the output from the differentiator 105 is bimorph 101
Has a cut-off frequency selected to attenuate the signals that contribute to the second and higher order resonance characteristics. 107 is a phase lead circuit that compensates for the phase delay of the output from the low-pass filter 106, 108 is a variable gain amplifier that variably inverts and amplifies the output from the phase lead circuit 107, and 109 is an output from a frequency compensator 115 and a gain variable An adder for adding the output from the amplifier 108, 110 is a drive amplifier for amplifying the output from the adder 109, 111 is a potentiometer to which the output from the adder 109 is supplied, 112 is a magnetic head, and cantilevered. It is supported on the free end of the bimorph 101. 113 is a video processing circuit that performs video processing on the output from the magnetic head 112, and 1
Reference numeral 14 denotes a head position control circuit, which forms a wobbling servo system and outputs a tracking correction signal from an output from the magnetic head 112.

A frequency compensator 115 receives an output from the head position control circuit 114 and an output from a converter reset signal generator 116 to be described later, and performs frequency compensation. Reference numeral 116 denotes a transducer reset signal generator which generates a reset signal to be provided to the deflectable support arm, that is, the bimorph 101, for selectively resetting the magnetic head 112 at the beginning of a track as necessary.

FIG. 15 is an external view of the bimorph 101 in FIG. 14, in which a magnetic head 112 is mounted. FIG. 16 is an improved example of FIG. 15, and the effective length of the bimorph 101 can be longer than that of FIG. FIG. 17 is also an improved example of FIG.
Is longer than that of Fig. 15.

FIG. 18 is a sectional view when the bimorph 101 is driven. FIG. 19 shows a geometrical calculation of the amount of tilt of the magnetic head (θdeg in FIG. 18) when the bimorph 101 is driven in relation to the effective bimorph length. 20th
The figure shows an example of the frequency characteristics of the bimorph 101.

FIG. 21 is an example of an electromagnetically driven actuator in which the magnetic head 112 does not tilt and the magnetic head 112 can move in parallel. In FIG. 21, reference numeral 201 denotes a magnet for generating an electromagnetic force;
02 is a yoke for forming a magnetic path, and 203a is a magnetic head 11.
2 is a gimbal spring for moving only one direction of freedom, 203b is a leaf spring for holding the magnetic head 112, 204
Is a bobbin for holding the actuator coil 205. FIG. 22 shows a frequency characteristic of the electromagnetically driven actuator in FIG.

FIG. 23 is an example of a control system configuration in the case where wobbling control is performed on the electromagnetically driven actuator shown in FIG. 21, for example, so that the amplitude of the reproduction signal from the magnetic head 112 is always maximized. In the figure, reference numeral 206 denotes an electromagnetic drive actuator, 207 denotes a head amplifier for amplifying a reproduced small signal from the magnetic head 112, 208 denotes a wobbling servo circuit, and 209 denotes a driver for driving the actuator 206.

Next, the operation will be described. In FIG. 14, the bimorph 101 includes an integrally formed sensor 102, which generates a signal indicating the instantaneous deflection position of the magnetic head 112. This output signal has a 90 ° phase delay with respect to the signal for driving the bimorph 101. This output is supplied to a high input impedance amplifier 103. Sensor 102
Since is equivalent to a voltage source in series with one capacitor, the electrical load on sensor 102 must be small to effectively couple the low frequency signal from sensor 102.

The output of amplifier 103 is provided to adder 104. Adder 10
The other input of 4 will be described later. The output of adder 104 is differentiator 10
Given to 5. This differentiator 105 differentiates the head position signal from the sensor 102 and converts it into a signal representing the instantaneous head speed. Since the differentiator 105 has frequency characteristics similar to those of the high-pass filter, a phase advance occurs in the passing signal. The head speed signal generated by the differentiator 105 is supplied to a low-pass filter 106, whose cut-off frequency is selected to substantially attenuate the signals that contribute to the second and higher order resonance characteristics of the bimorph 101. ing. Low pass filter 106 imparts a certain phase delay to the signal passing through it. The phase advance circuit 107 includes a bimorph 10 to compensate for any phase lag experienced by signals near the resonance position.
The signal component of the frequency near the resonance point of 1
Phase shift so as to have a net phase shift of 0 °. The output signal of this phase lead circuit 107 is the inverted gain variable amplifier 1
08, the output signal of the amplifier 108 is added to the output of the frequency compensator 115 described later in the adder 109, and the driving amplifier 11
The signal is amplified by 0 and given to the bimorph 101 as a deflection signal to attenuate its resonance vibration. The gain of the variable gain amplifier 108 is adjusted so as to cope with the variation in the characteristics of the bimorph 101.

On the other hand, the signal component near the anti-resonance point is effectively zero-tuned by combining a part of the drive signal supplied to the bimorph 101. The deflection signal of the adder 109 is a potentiometer 111
The output of the potentiometer 111 is supplied to the other input terminal of the adder 104, and is added to the deflection position signal detected by the sensor 102 input from the amplifier 103. Since the phase of this deflection signal undergoes a 180 ° phase shift when detected by the sensor 102 via the bimorph 101, the frequency components of the deflection signal near the anti-resonance point are adjusted to zero by the adder 104. Thus, the loop is stabilized for frequencies near the anti-resonance point.

The dimorphing operation of the bimorph 101 should be performed as described above, and stable tracking control should be possible.

However, since the bimorph 101 in FIG. 14 is arranged on the rotating drum as shown in FIG. 15, during a large amplitude operation such as during special reproduction of a VTR, the bimorph 101 is displaced as shown in FIG. At the time of ξ displacement, the magnetic head 112 has a tilt θ. It goes without saying that this deteriorates the contact state between the magnetic head and the magnetic tape, and particularly deteriorates the high frequency characteristics of the recording / reproducing signal. In order to improve this, a shape of the bimorph 101 has been proposed in which the effective length of the bimorph actuator can be increased as shown in FIGS. 16 and 17, but if the effective length is increased, the head tilt in FIG. Although the amount (deg) becomes smaller, the resonance point frequency and the anti-resonance point frequency in FIG. 20 shift to lower ones. In a general bimorph actuator, the phase is 18 after the primary resonance frequency.
Since it has a characteristic of turning around 0 °, in a tracking control system using a movable head, the control band is set to a frequency sufficiently lower than the resonance frequency (however, the primary resonance frequency and the secondary or anti-resonance frequency are set). Is sufficiently distant, it is possible to take a control band between the primary and secondary or anti-resonance frequencies by phase lead compensation). Therefore, a bimorph actuator with an extremely large effective length
With 101, it is difficult to configure a control system that does not have a sufficient control band and can sufficiently follow the track bending of the magnetic tape. Of course, it is possible to reduce the resonance peak gain of the bimorph actuator to some extent by using the above-described differentiating circuit.However, since the differential operation is performed, the noise included in the deflection position signal is amplified, and diping is performed for mechanical resonance. The gain of the die pin group which applies is not large. As described above, in the bimorph type actuator, when the actuator operates, the magnetic head
There is a trade-off between making good contact between the magnetic tape 112 and the magnetic tape, that is, reducing the head tilt of the magnetic head 112 and shifting the actuator mechanical resonance to a higher frequency or reducing the resonance peak gain. In addition, the damping control using the differentiating circuit has a limit in amplifying a noise component of the position sensor.

However, as a configuration for keeping the contact between the magnetic head 112 and the tape good even during a large amplitude operation, a configuration of an electromagnetically driven actuator as shown in FIG. 21 can be considered. 21st
In the figure, the magnetic flux generated by the magnet 201 is
Since the coil 205 is generated in a certain gap portion through the magnetic path constituted by the magnetic path 02, an electromagnetic repulsive force is generated by applying a current to the coil 205, thereby deforming the gimbal spring 203a, and Translate 112. Since the magnetic head 112 moves in parallel to the last, the contact between the magnetic head 112 and the tape is always kept good even during the large amplitude operation. However, even in the above-described electromagnetically driven actuator, the phase rotation occurs due to the mechanical resonance of the gimbal spring 203a and the leaf spring 203b, and the phase is rotated 180 ° after the primary resonance frequency as shown in FIG. In addition, the tracking control band can only be set to a frequency sufficiently lower than the primary resonance frequency. If the control band is forcibly increased, the tracking system will oscillate due to problems such as the phase margin of the control system deteriorating around the mechanical resonance phase and the gain margin deteriorating due to the mechanical resonance peak gain. There was a fear. As a method of the tracking control system, a pilot signal for tracking servo is recorded on a recording track, recording data or a different frequency is multiplexed for each track in a gap on the recording signal frequency allocation, and a crosstalk signal from both sides is obtained during reproduction. By comparing the level of the pilot signal, a pilot method for detecting the direction and amount of the track deviation, and as shown in FIG. 23, the movable magnetic head is slightly vibrated, and the vibration frequency component in the reproduced signal envelope at this time is calculated. And synchronous detection based on magnetic head vibration command information. There are two general wobbling systems in which tracking is performed using signals indicating the direction and amount of track deviation. In either of these methods, as described above, keeping the mechanical resonance peak gain of the electromagnetically driven actuator or bimorph actuator low improves the performance of the tracking control system. In particular, even when using an electromagnetically driven actuator with good head contact even during large-amplitude operation, if the thickness of the gimbal spring is increased to increase the mechanical resonance frequency for the above-described reason, the force constant of the actuator must be increased. Since the predetermined amplitude cannot be obtained, the size of the actuator becomes large, and it was impossible to simply increase the mechanical resonance frequency. Since the actuator for moving the magnetic head as described above is configured in the rotating drum of the VTR, it has a mechanical configuration that separates the drive unit from the magnetic head 112, and is inevitably configured by a leaf spring (including a gimbal spring). (203a, 203 in FIG. 21)
b, FIG. 15, FIG. 16, and FIG. 17). Therefore, mechanical resonance is likely to occur and the peak gain is large, so that the controllability is not very good.

[Problems to be solved by the invention]

Since the conventional magnetic head driving device is configured as described above, a large mechanical resonance occurs, and the servo band cannot be widened due to the influence of the phase rotation and the deterioration of the gain margin due to the resonance peak gain. It has been difficult for the magnetic head to follow the track bend while minimizing the control deviation.

The present invention has been made in order to solve the above-described problems, and even if the actuator has a large mechanical resonance, the servo band can be stably widened and the actuator can be damped without using a differentiating circuit. The purpose is to be able to call.

[Means for solving the problem]

A tracking control system in a magnetic reproducing apparatus according to claim 1 of the present invention includes: an actuator for displacing a magnetic head mounted on a rotating drum in a tracking direction; a position detecting means of the actuator built in the actuator; A feedback unit that performs feedback of position information or feedback of speed information to the actuator based on a detection output from the position detection unit, and feedback of the speed information, a position detection unit from the position detection unit of the actuator, The operation is performed using speed information estimated by speed estimation means having an equivalent circuit simulating the mechanical characteristics of the actuator, with the drive signal of the actuator being input, and the speed estimation means is fixed in the rotating drum. Circuit base Those composed configured above.

In claim 2, the position detecting means is an optical position detecting means constituted by a light emitting means provided on a movable part and a fixed part of the actuator and a light receiving means divided into two.

According to a third aspect of the present invention, the detected position information from the optical position detecting means is converted into an AC signal by blinking the light emitting means, and the position converted into AC by a rotary transformer mounted on the rotating drum. A detection signal is transmitted.

According to a fourth aspect of the present invention, the actuator includes: a cylindrical electromagnetic driving portion including a coil and a permanent magnet; a plate-shaped magnetic head fixed portion fixed to the cylindrical movable member; And an optical position detecting means having a light receiving element.

According to a fifth aspect, the optical position detecting means is constituted by a reflecting mirror attached to a movable portion of the actuator, and a light emitting portion and a light receiving portion attached to a fixed side.

[Action]

In the present invention, by feeding back the obtained estimated speed of the actuator to the actuator drive signal, the actuator can be electrically damped, mechanical resonance of the actuator can be suppressed, and controllability can be improved.

In addition, since the accurate speed can be estimated by using the position detecting means and the speed estimating means, a large speed feedback gain can be obtained and a large damping can be applied.

In the present application, the speed estimating means is configured on a circuit board fixed in a rotating drum. That is, since the speed estimating means itself is configured to be mounted inside the rotating drum, when transmitting the output signal from the speed estimating means to the outside of the rotating drum, an output signal is generated based on a minute signal such as a sensor signal. Even when the signal is transmitted, it can be transmitted to the outside as a large-level signal with little influence of noise. Thereby, the influence of noise due to transmission to the outside of the rotating drum can be reduced.

Furthermore, considering only the ability to follow the special playback waveform,
This is effective when a small amount of electrical damping is sufficient and cost reduction is required.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a transfer function block diagram of an observer (state observer). In the figure, reference numeral 301 denotes a transfer function expression of an actuator mechanism for moving the movable magnetic head 112, 302 denotes a coil resistance of an actuator, and 303 denotes a gain of a drive amplifier. is there. Reference numerals 304 to 310 denote transfer function expressions of the observer 402 corresponding to the speed estimating means of the present application. Reference numeral 304 denotes a portion equivalent to a spring constant in the actuator model, and reference numeral 305 denotes an actuator coil resistance, an actuator torque constant, and a drive amplifier gain. Equivalent part, 306 is the part that equalizes the viscosity constant of the actuator and the mass of the movable part, 307 is the transfer function expression of the integral characteristic, 308 is the above 304 to 3
Observer gain inserted to stabilize the loop in which the error between the state model up to 07 and the actual measurement converges, 309
Is an observer loop gain for converging an error similar to the observer gain 308, and 310 is a speed feedback gain for feeding back the estimated speed.

FIG. 2 is a comparison diagram of actuator transfer characteristics (gain characteristics and phase characteristics) when damping groups are applied by the observer of FIG. 1 and when they are not applied.

FIG. 3 shows an example of the configuration of a tracking control system composed of the observer shown in FIG. 1. In FIG. 3, reference numeral 401 denotes an actuator driver built in the drum, and 402 denotes a state observation represented by a transfer function as shown in FIG. 403 is a drum rotation control circuit for rotating the rotary drum, 404 is a pilot signal generation circuit for generating a pilot signal for performing tracking control during reproduction in synchronization with the rotation of the drum, 405 Is a modulation circuit that performs modulation so that a pilot signal is multiplexed with recording data when recording digital information, for example. A current flows through the magnetic head 112 during recording, and a small reproduction signal is amplified during reproduction. A head amplifier 407 generates a signal indicating the direction and amount of track deviation from a pilot signal included in the reproduction signal. Over generation circuit, 40
Reference numeral 8 denotes a tracking control compensating circuit for operating the tracking control loop stably and reliably. Reference numeral 409 denotes a capstan control circuit that controls a capstan motor based on a low-frequency track shift component among track errors. Reference numeral 410 denotes a rotating drum, 411 denotes a slip ring for supplying an electric signal (including a power source) to the rotating drum from the outside, 412 a rotary transformer for transferring signals between the rotating drum and the outside, and 413 an actuator It is a position sensor attached to 206 to detect the displacement of the actuator movable part, and corresponds to the position detecting means of the present application.

FIG. 4 (a) shows an example of a configuration for detecting the position of an actuator movable portion by a Hall sensor. In the figure, reference numeral 501 denotes a magnet holder for reducing magnetic flux leakage to the magnetic head 112; 502, a magnet for generating magnetic flux; Is a Hall sensor for detecting the magnitude of the magnetic flux of the magnet 502, and 504 is a differential amplifier for amplifying a small signal from the Hall sensor 503 to obtain a position signal. FIG. 4 (b) is a modification of FIG. 4 (a).
Is a Hall sensor, and 507 is a substrate for fixing the Hall sensor 506. FIG. 5 shows an example in which a control system using the observer is configured by position detection by the Hall sensor. In FIG. 5, reference numeral 508 denotes a substrate built in the drum. That is, the speed estimation observer 402 itself is formed on the circuit board 508 fixed in the rotating drum 410.

FIG. 6 (a) shows an example in which a position detecting means using an optical sensor is attached to an actuator. In the figure, reference numeral 601 denotes a light emitting unit for emitting parallel light, and 602 denotes a two-part detector (light receiving unit) constituted by a photodiode or the like. Part). FIG. 6 (b)
6A is a modified example of FIG. 6A. In the figure, 603 is a lens for converting light from the light emitting element 605 made of an LED or the like into parallel light, 604 is an exit window (squeezing), and 606 is a lens 603. This is a mirror for reflecting parallel light from the camera. FIG. 6 (c)
FIG. 6B is a diagram showing the principle of detecting the displacement of the movable part of the optical sensor in FIG. 6B. Reference numeral 607 denotes a differential amplifier for detecting and amplifying the photocurrent in the two-divided detector 602.

FIG. 7 shows an example of a configuration in which the above-described observer circuit and driver circuit are not built in the rotating drum by using the position detection of the actuator by the optical sensor. In the drawing, reference numeral 608 denotes a detection circuit.

FIGS. 8 (a), (b) and (c) show the tracking control system and actuator characteristics of the movable head and the open loop characteristics (gain characteristics) of the control system of the capstan motor control system when an observer is formed. Things.

FIG. 9 is an example of actual open-loop characteristics when a tracking control system is configured after an observer is configured in the electromagnetically driven actuator.

FIG. 10 (a) shows the above-described observer configured in a wobbling system in which tracking is performed only from a change in a reproduction signal envelope by recording a pilot signal for tracking control at the time of recording and by slightly vibrating a movable magnetic head. It is a principle block diagram in the case. In the figure, 701 is a band-pass filter for extracting only the wobbling frequency from the reproduced signal, 702 is a synchronous detection circuit for extracting the direction and amount of track shift from the signal from the band-pass filter 701, and 703 is an actuator for the wobbling frequency. 704 is an inverting amplifier, 705 is an oscillator that generates a reference signal for performing a wobbling operation, and 706 is an addition that adds a wobbling signal for slightly oscillating a control signal. 707 is a subtractor for feeding back the estimated speed of the observer, and 708 is a low-pass filter (compensation circuit) for keeping the stability of the control loop. FIG. 10 (b) is an example in which the principle configuration of FIG. 10 (a) is described more specifically. In the figure, 709 is a fixed head, and 710 is a phase for removing jitter contained in a drum rotation angle detection signal. Locked loop (PLL) circuit, 711 is magnetic head 11
A head amplifier 712 for amplifying a small signal from 2 is an auto gain control (AG) which is configured so that the amplitude of the reproduction envelope from the head amplifier 711 is constant regardless of the variation of the magnetic head or the variation of the tape.
C) Circuit, 713 moves the required band of the control signal.
112 is a low-pass filter for supplying the actuator 206, 714 is a low-pass filter for supplying the low-frequency component of the control signal to the capstan motor 718, and 715 is the CTL that converts the phase information from the CTL pulse written in the linear track.
A capstan phase control circuit for reading with the head 719 and performing phase control by this, a 716 adds a phase control loop by CTL and a control loop by wobbling, and an addition for controlling the capstan motor 718 via a driver 717. It is a vessel. FIG. 10 (c) is a diagram showing a state where the heads 112 and 709 are tracing the recording track pattern.

FIG. 11 is an example of a circuit configuration of the above-described observer.
In the figure, 801 is a capacitor for extracting only the AC component of the actuator drive voltage, 802 is an amplifier for adding and amplifying the feedback signal and the drive voltage in the observer, and 803 is a loop simulating the spring constant in the observer. An amplifier for feedback, 804 is a filter for realizing transfer characteristics simulating the viscosity and mass of the actuator in the observer, 805 is a filter constituting an integrator in the observer, 806 is positional information and estimated positional information of the observer A comparison circuit for extracting the difference between
807 is a capacitor for extracting only the AC component included in the position information, and 808 is a capacitor for outputting only the AC component included in the estimated speed information.

FIG. 13 shows a pole arrangement of an actuator, a tracking control system, and an observer.

FIG. 12 (a) is a principle diagram of a simple diping control circuit using a back electromotive force. In the figure, 901 is an equivalent coil having the same electric characteristics as the actuator coil, 902 and 903 are current detection resistors, and 904 is a back electromotive This is a differential amplifier for power detection.

FIG. 12B shows an example of a damping circuit configuration based on actual back electromotive force feedback. In the figure, reference numeral 905 denotes a resistor simulating the resistance component of the actuator coil; 906, a coil simulating the inductance of the actuator coil;
7,908 is a differential amplifier for extracting the voltage between both ends of the current detection resistors 902 and 903, 909 is a differential amplifier for extracting the back electromotive force, 910 is a filter for limiting the band of the current feedback loop, and 912 is a back electromotive force feedback Filters 911 and 913 for limiting the band of the loop are capacitors for removing the DC component of each loop.

 Next, the operation of the embodiment will be described.

In order to achieve high-density recording and high-speed noiseless special reproduction, an actuator with a large movable range and good head contact follows the recording track bend, and performs large amplitude operation during special reproduction. It needs to be realized.

In order to move the magnetic head in the drum, it is necessary to move the magnetic head only in one axis direction, that is, in a direction parallel to the rotation axis of the drum, and the cantilever can be seen in the bimorph type and the electromagnetic drive type shown in the conventional examples. Make the structure like a member or a leaf spring shape, separate the drive unit and the magnetic head, or
It is necessary to attach the head to the plate-like tip.

For this reason, the transfer characteristics (displacement-drive voltage or current characteristics) of the actuator in the case of the conventional bimorph type actuator or the case of the electromagnetic drive type actuator
As can be seen from FIG. 2, there was a large mechanical resonance characteristic of the leaf spring configuration (FIGS. 20 and 22).

Since this large mechanical resonance rotates the phase by 180 ° near the resonance frequency, for example, when a tracking control system with phase lag compensation is configured, the frequency is sufficiently lower than the primary resonance frequency, generally, the primary resonance frequency. 1/10 ~
Only about 1 / several tens of control bands could be obtained. This is because, first, the phase margin of the control system cannot be sufficiently secured due to the influence of the phase around the resonance, and second, if the resonance peak gain is large, the gain margin after the control band frequency (generally, Specifically, the control system open-loop gain at a frequency where the phase in the frequency region higher than the control band frequency is -180 ° needs to be -10 to -20 dB) becomes smaller due to the resonance peak gain, and This is because the system becomes unstable. Also, when a control band is provided between the primary resonance and the secondary by performing phase lead compensation, the primary mechanical resonance frequency and the secondary resonance or antiresonance frequency need to be sufficiently separated from each other. In a system having a leaf spring-shaped movable portion such as that found in a tracking actuator of a movable magnetic head of a VTR,
Since the frequency difference between the secondary resonance and the second and subsequent resonances cannot be obtained, the lead compensation is not often used. Therefore, it is necessary to electrically dampen a large mechanical resonance characteristic peculiar to the movable magnetic head actuator of the VTR to change the actuator into a highly controllable actuator. However, when a differential circuit is used as in the conventional example, the noise of the position sensor is amplified, and the tracking control performance is rather deteriorated. Therefore, as shown in FIG. 1, if the actuator speed is estimated by a state estimator (hereinafter abbreviated as an observer) using an integrating circuit, noise is not amplified, and for the reasons described later, higher order The effect of mechanical resonance can be eliminated. The observer represented by the transfer function in FIG. 1 is an example of the configuration of the same-dimensional observer in the modern control theory. In the observer circuit, an equivalent circuit 305 simulating the characteristics from the drive amplifier 303 to the actuator mechanism 301 is provided.
307 are inserted. In the figure, the actual drive voltage input to the drive amplifier 303 is also input to the equivalent circuit in the observer, and a signal obtained by estimating the position of the actuator from the equivalent circuit input at point a in the figure is output as an equivalent circuit output. . On the other hand, the actual displacement of the actuator is
A signal actually measured by a sensor or the like to be described later is output to point b in the figure, and the difference, that is, ba, is extracted as an estimation error. In this case, the transfer characteristic of the circuit forming the equivalent circuit in the observer has a quadratic integral characteristic, and does not simulate the integral characteristic of the actual actuator even in the initial state. Because the disturbance cannot be simulated in the equivalent circuit even though the disturbance is input before the integral characteristic, the dynamic characteristics (equivalent circuit) Are not the same for each time lapse in the output value of (1). Therefore, feedback is applied by the gains 308 and 309 of F1 and F2 so that the estimation error converges to zero. Therefore, after a certain time has elapsed, the estimation error converges to zero due to the effect of the feedback gain in the observer, so that the estimated position a, which is the equivalent circuit output, and the actually measured position b become equal. At this time, the position before the integrator 307, ie, 1 The portion corresponding to the actuator speed which is the output of the block 306 of / c + Ms (corresponding to the speed because it is a position component on the circuit) is equal to the actual actuator speed.

The actuator speed estimated based on the above principle is
When the feedback is made to the original control loop with the gain 310 of F3, the speed feedback loop is newly constructed (the same as the configuration of the regulator in the modern control theory), and the mechanical resonance characteristics of the actuator are damped. FIG. 2 is an actual measurement diagram of the actuator frequency characteristics that proves the above, and the characteristics when an observer is configured and speed feedback is applied are damped.
The resonance peak gain decreases. Although the speed estimation observer described above has been described as being constituted by the same-dimensional observer of modern control theory, it goes without saying that the same effect can be obtained even if it is constituted by the minimum-dimensional observer. In this case, there is no equivalent circuit as described above,
A result obtained by solving an expression expressing the actuator characteristics by a state equation by a general minimum dimension observer construction algorithm (for example, Gopinas minimum dimension observer) is realized by a circuit as it is. Here, F1 gain 308 and F2 gain 309 in the same dimension observer are set as follows: M: Actuator movable part k: Actuator mass C: Actuator viscosity u: Input C _e : Estimation error: Observer output Assuming that the observer poles are −α ₁ and −α _{2 according} to the definition of an arbitrary pole arrangement in modern control theory, the values of F1 and F2 are It is only necessary to find F1 and F2 that satisfy the conditions.

However, the convergence of the loop including the loop and F2 gain 309 including the F1 gain 308 in the observer, because of the fast enough required than the convergence of the overall tracking control system, the value of alpha ₁ and alpha ₂ in equation 2, the In the pole arrangement shown in Fig. 13 (a diagram representing the response of the system in control theory), set to the left side (the side with larger negative real values = faster convergence side) than the pole of the regulator system (the pole of the tracking control system). There is a need to. Also, in FIG.
Although the characteristics of the actuator mechanism have been simplified as a secondary system, there are actually many higher-order resonances and antiresonances in a leaf spring-shaped actuator, and these degrade the gain margin of the control system. May have adverse effects. However, also in this case, if the band of the feedback loop (the loop including the F2 gain 309) in the observer (frequency at which the open loop gain becomes 0 dB) is set as follows, the above-described high frequency can be obtained by using such an observer. It is also possible to suppress the influence of the next resonance.

 Hereinafter, the above reasons will be proved.

First, assuming that the characteristics of the actuator mechanism are Kt: actuator torque constant Gm: higher-order resonance characteristics, Kt · Gm / (MS ² + CS + k): Equation 3 (Equation 3) = B (s) · Gm Equation 4 In summary, in FIG. 1, for simplicity, R
= 1, Kd = 1, F2 = 0, the transfer function from the drive voltage to the estimated speed is: u (t) · B (s) · S · ｛(1+ (F1) · B (s) · Gm) / (1+ (F1) · B (s))｝ Equation 5 The transfer function from the drive voltage to the true actuator speed is V = u (t) · B (s) · S · Gm Equation 6 Therefore, comparing Equations 5 and 6, Gm expressed by
It is understood that the coefficient of (F1)） B (s) / (1+ (F1) ・ B (s)) is applied to Gm represented by V.

F1 · B (s) is equal to the open-loop characteristic of the observer, and Equation 7 is a closed characteristic. Therefore, if the above-mentioned band is set so that the tracking control band <observer band <high-band mechanical resonance frequency = fm, the closed characteristic can be obtained. Gain is 0dB in the frequency range higher than the control band at
Since (F1) · | B (fm) | / (1+ (F1) · | B (fm) |) <1 (8), the coefficient of Gm in Equation 5 is the coefficient of Gm in Equation 6. In the frequency range where the velocity feedback is applied by the observer in FIG. 1, the influence of high-frequency mechanical resonance can be reduced.

A movable head tracking control system using an observer as described above can be configured, for example, as shown in FIG. When the position of the movable head 112 is detected by the position sensor 413, the position detection signal indicates the number of channels of the rotary transformer 412,
In some cases, the slip ring 411 cannot be taken out of the drum in consideration of the influence of sliding noise. In this case, as shown in FIG. 3, the driver 401 for the actuator and the speed estimation observer 402
And the actuator including the electric damping can be realized from the outside of the drum via the slip ring 411. FIG. 3 shows an example in which an observer is configured in a tracking control system of a digital recording VTR for which high density is required by narrow track recording, and a generation circuit 404 generates a pilot signal necessary for detecting a tracking error. The DC component (CDS value) of each block of digital data is varied based on the pilot signal, and the output of the modulation circuit 405 for multiplexing the pilot signal with the digital data is recorded, thereby generating a track error during reproduction. It is generated by the circuit 407 and performs a tracking operation. At this time, the digital data CD
Even if the pilot signal is added in an analog manner instead of the method of changing the S value, there is no problem if the pilot level is sufficiently lower than the recording information signal level. In the case of analog recording (FM recording VTR), the pilot signal may be multiplexed in a gap on frequency allocation. The tracking error obtained as described above is phase-compensated and gain-compensated by the compensating circuit 408, and a relatively high-frequency component such as a track bend is fed back to the movable head, and a relatively low-frequency component such as a track deviation is obtained. Is fed back to the capstan motor, so that the movable head side does not exceed the dynamic range.

In order to configure the observer as described above, a position sensor for detecting the position of the movable head is indispensable. FIG. 4 (a) shows an example of the movable head.
To detect the movement of 112, move the magnet 502
The Hall sensor 503 detects the value of the magnetic flux density caused by the magnet 502 approaching or moving away from the movable part 203b, and takes out the value as the output of the amplifier 504, thereby detecting the position of the movable part. it can. At this time, the magnet 502 is surrounded by a magnet holder 501 made of a member having a high magnetic permeability so that the leakage magnetic flux does not affect the magnetic head 112. FIG. 4B is a modification of FIG. 4A, in which a magnet 505 is fixed to a gimbal spring 203a on the side of the movable part 203 of the actuator that does not have a magnetic head. Magnet leaking to the outside
The configuration is such that the magnetic flux of 505 is detected by the Hall sensor 506 fixed on the substrate 507. Here, the intensity of the magnetic flux from the magnet 505 indicates the position of the movable portion, which is the same as in the case of FIG. 4 (a). In this modification, the influence of the leakage magnetic flux of the magnet 505 on the magnetic head 112 need not be considered.

In addition to the magnetic position detecting means described above, there is a method using an optical position detecting means. For example, FIG. 6 (a) shows an example in which light from a light emitting unit 601 attached to the fixed side of an actuator (in this case, parallel light by a lens) is attached to a movable unit.
The light is detected by the light receiving unit 602 such as a split photodiode. When the moving part moves, the photodiode 60
Because the amount of light that strikes one side of 2 is greater than the other,
The position of the movable part can be detected by taking the difference between the photocurrents of the respective photodiodes 602. FIG. 6B is a modification of FIG. 6A, in which only a mirror 606 for reflecting light is attached to the movable part, and a light emitting part 601 and a light receiving part 6 such as a photodiode are provided.
02 is on the fixed side. Also in this case, light from the light emitting element 605 constituted by an LED or a semiconductor laser is converted into parallel light by the lens 603. At this time, in order to obtain parallel light, the light emitting element 605 needs to be disposed at the rear focal position of the lens 603. The position of the optical sensor shown in FIG. 6B is detected based on the principle shown in FIG. 6C.

In FIG. 6C, when the mirror 606 integrated with the movable portion moves in parallel (in this case, the gimbal spring or the like restricts the mirror to move only in one axial direction), the emitted parallel light is emitted. 6A moves in parallel with the movement of the movable unit on the light receiving unit 602, and therefore, for example, a difference occurs between the photoelectric flow rates of the two-division photodiodes 602 as in FIG. A signal is obtained. It goes without saying that the same effect can be obtained by attaching the light emitting section to the movable section and setting the light receiving side to the fixed section, in addition to the above-described method.

In addition to the above-described magnetic or optical position detecting means, an element generally called a strain gauge whose magnetic resistance changes when distorted is attached to a leaf spring or a gimbal spring of a movable head actuator. By
The deformation of the leaf spring or gimbal spring is detected as a change in resistance value. For example, the change in voltage when a constant current is applied to the above-described strain gauge is read, or the current inserted in series with the strain gauge when a constant voltage is applied. A method of detecting the position of the movable portion by reading the voltage between both ends of the detection resistor is also possible.
In addition, a sensor for detecting a capacitance near the movable portion is provided, and the distance between the capacitance sensor and the movable portion is arranged so as to change as the movable portion moves, and the capacitance of the capacitance sensor is electrically detected. Thus, it is possible to detect the position of the movable part. When a conventional bimorph actuator is used, it is needless to say that an amount other than the DC component in the bimorph displacement can be extracted by cutting off a part of the bimorph as shown in the conventional example. In this case, a DC component is not included in the displacement output, but the observer in FIG. 1 does not necessarily require a DC component, and thus can be input as a position detection signal used for the observer. However, at this time, it is needless to say that if the DC component is not cut in the input of the driving voltage of the observer as well, a DC prediction error occurs in the estimation error and the observer does not operate.

Here, when the position detection signal cannot be taken out of the rotary drum, the driver 401 or the actuator 401 of the actuator is provided in the substrate 508 by the ring-shaped substrate 508 mounted in the drum as shown in FIG. A sensor amplifier 504, an observer 402, and the like are configured and can be operated based on an actuator drive command voltage from the slip ring 411.
This can be directly applied to all the position detection methods described above.

On the other hand, it is also possible to take out the position detection signal outside the rotary drum and configure the observer circuit and the driver outside the drum. For example, FIG. 7 shows an example in which an LED or a laser as the light emitting element 605 of the optical sensor is driven to blink by a drive signal in the figure. At this time, the blinking frequency is sufficiently higher than the observer band, and is set to a frequency range in which the rotary transformer 412 can pass. In the figure, the slip ring 41
Although the drive signal of the light emitting element 605 is transmitted by 1, the drive signal is transmitted by a rotary transformer having a large capacity,
Similarly, a method in which only the power is supplied by another means (a rotary transformer or a slip ring having a large capacity) and only the command signal is transmitted can be used to perform the blinking drive.

The light that has been turned on and off in this manner is converted into an AC photocurrent by the light receiving element 602 via the mirror 606. Since this photocurrent is a photocurrent signal in a frequency region that can pass through the rotary transformer, the
After passing through 412, the light receiving element is detected by the detection circuit 608 outside the rotating drum.
It is converted into the amount of light received by 602 and can be extracted by the differential amplifier 607 as the amount of displacement of the actuator movable part.

In addition, even in the case of the above-described capacitive sensor, even if it is not the case of the optical sensor as shown in FIG. After taking out the AC signal from outside the rotary transformer, frequency-voltage conversion (F / V conversion) may be performed to take out the movable part position signal. Besides this method, a voltage-frequency conversion (FM modulation) circuit, a voltage-pulse width conversion (PWM modulation) circuit, or a voltage-AC amplitude conversion (AM modulation) circuit prepared in the drum may be used. Needless to say, the same effect can be obtained by taking out the drum through the rotary transformer 412.

The electric damping of the magnetic head actuator constituted by these position detecting means and the observer circuit is as follows.
The resonance peak gain is suppressed as shown in FIG. 8 (b), and as a result, the tracking control system of the actuator can be configured as shown in the control system open loop characteristic B in FIG. 8 (a). When there is no electrical damping due to the above, since the peak gain at the resonance frequency d 'has risen, the control band must be lowered to g' in order to maintain stability in consideration of the gain margin at point d '(at this time, , Frequency d ', the phase in the control system open loop characteristic is as large as -180 °, so that the open loop gain of this frequency d' is 0d
The control system oscillates when approaching B). Also, when the tracking error reducing component is returned to the capstan motor,
Since the capstan motor has an open loop characteristic as shown in FIGS. 8 (a) and 8 (b), an integrated control characteristic when both the capstan loop and the tracking loop are closed simultaneously is shown in FIG. 8 (a). ) Is obtained at each frequency. That is, the capstan loop becomes dominant on the low frequency side, and the actuator loop becomes dominant on the high frequency side. For example, FIG. 9 shows an example of an open loop characteristic of the actuator tracking control system.

FIG. 3 shows an example in which the observer is applied to the case where the pilot signal from the recording track is reproduced and the direction and amount of the track deviation are detected. However, the pilot signal is not stored, and the magnetic head 112 is slightly vibrated. Even in the wobbling method that performs tracking based on the change in the output amplitude of the reproduced signal at this time, unnecessary mechanical resonance of the actuator can be suppressed, control band can be improved, stability can be improved, and unnecessary vibration can be prevented. It is.

FIG. 10 (a) shows an example in which only the wobbling frequency component included in the extracted reproduced signal amplitude is extracted by the band-pass filter 701.
The phase shifter converts the command signal that causes the actuator to vibrate minutely.
In 703, the direction and amount of the track shift can be detected by synchronous detection or multiplication using a signal whose phase has been shifted by the mechanical phase delay amount at the minute vibration frequency of the actuator. The track error signal obtained in this way is phase-compensated by a low-pass filter 708, added to a wobbling signal for micro-vibrating the actuator, and the observer output is fed back by a subtractor 707. , The tracking can be performed.

FIG. 10 (b) shows a specific example in which the low frequency component of the track error is fed back to the capstan motor in the wobbling method in FIG. 10 (a). A low-frequency component whose phase is compensated from a track error due to wobbling is fed back to a phase control loop based on a CTL (phase detection) signal from a linear track.
In FIG. 10 (b), there is a fixed head 709 in addition to the movable head 112 by the actuator 206, but since the low frequency component of the track error is always fed back to the capstan motor 718, the movable head is always movable with respect to the fixed head 709. The head height of the head 112 is automatically adjusted, and the movable head 112 follows only the track bend. In general, in the case of a head configuration as shown in FIG. 10 (b), the head width of the fixed head 709 is set wider than the track width as shown in FIG. 10 (c), and the signal is sufficiently spread even if the track is bent. It is general that it is constituted as follows.

When the actual observer circuit is constituted by, for example, an analog circuit, it is realized as shown in FIG. In analog differential amplifiers and the like, offsets are likely to occur due to temperature drift, etc., so when using an analog circuit, the capacitors 801 and 807 that remove the DC component in the actuator drive voltage input to the observer circuit and the position information input from the position sensor are used. It is desirable to insert. The reason is that the frequency range in which the damping is mainly required in the tracking control system is near the frequency at which the mechanical resonance exists, so that the DC component is not required. The circuit of FIG. 11 simulates the observer transfer characteristic of FIG. 1 as it is, and R, Kd, Kt, k, F1, and F2 in FIG. 1 are used as the amplification gain of the operational amplifier in FIG. Exists, Block 306 is constituted by an active filter of an operational amplifier 804, and the integrator 307 is constituted by an integrator of the operational amplifier 805. The subtraction part of a-b in FIG. 1 is constituted by an operational amplifier 806. The output of the operational amplifier 806 has gains corresponding to F1 and F2 in FIG. 1, respectively, and the operational amplifiers 802 to 805 of the observer equivalent circuit. Feedback. Further, in the configuration of FIG. 11, it is possible to configure the operational amplifiers 803 and 804 as one active filter and omit one operational amplifier.

Although the above configuration is an example in which the observer is configured by an analog circuit, the same effect can be obtained by describing the transfer function expression of FIG. 1 by software in a microcontroller or the like.

Although the above-described method has been described with respect to an example configured in a VTR, it is needless to say that the same method can be applied to a tracking control system for a magnetic disk device or an optical disk device.

As described above, the method of configuring the movable head actuator with the observer and performing the electrical damping has been described.
There is a case where the movable head is used only for special reproduction without performing the tracking operation by the movable head as seen in all commercially available VTRs and the like. Also in this case, it is necessary to accurately perform the movement of the actuator with respect to the special reproduction waveform and suppress mechanical resonance in order to suppress unnecessary vibration. At this time, it is needless to say that mechanical resonance and unnecessary vibration can be suppressed by applying electric damping with the system using the observer circuit and the position sensor as described above, but only considering the followability to the special reproduction waveform, When a small amount of electric damping is sufficient and it is necessary to reduce the cost, a simple damping method using back electromotive force feedback as shown in FIG.
This is done by connecting an equivalent coil 901 having the same electrical characteristics as the actuator coil to the driver 401 in parallel, comparing the current flowing in each current path with the current detection resistors 902 and 903, and comparing the back electromotive force to the output of the differential amplifier 904. (In this case, since the equivalent coil 901 does not move and no back electromotive force is generated, the voltage between the resistors 903 and 902 is equal to the potential difference due to the back electromotive force of the actuator coil. And this is detected). However, since a difference occurs between the equivalent coil 901 and the coil in the actuator 206 due to a temperature drift or the like, the detected back electromotive force is not accurate. So, the twelfth
Simple damping is configured by a circuit configuration as shown in FIG. The voltage between both ends of the current detection resistors 902 and 903 is detected by the differential amplifiers 907 and 908. Since the output of the differential amplifier 907 corresponds to the drive current of the actuator 206, this is limited to a necessary band by a filter 910, and then fed back to the original control system via a capacitor 911 for removing a DC component. The actuator drive method can be set to voltage drive (in the frequency range where current feedback is not performed) or current drive (in the frequency range where current feedback is performed) depending on the cutoff frequency range of the filter 910. It is possible. Further, two current detection resistors 902 and 903 are provided by a differential amplifier 909.
By detecting the voltage difference between both ends of the actuator,
By taking out the back electromotive force of 6 and limiting the band by the filter 912 and feeding it back via the capacitor 913 that removes the DC component, the feedback loop of the back electromotive force can be electrically configured and damped. It is possible. The amount of feedback can be varied by varying the gain of the differential amplifier 909, and the amount of damping can be varied. Further, the filter 912 is a band-pass filter that passes only the mechanical resonance frequency component of the actuator,
It goes without saying that the effect of mechanical resonance can be reduced.

Since the back electromotive force detected here is generated in proportion to the speed of the actuator, it is the same as the estimated speed estimated from the speed observer described above. it is obvious. However, the estimation of the observer and the detection of the back electromotive force, if the accuracy of the position sensor used for the observer is good, considering the suppression effect of the higher-order mechanical resonance of the observer and including only the integrator in the circuit, etc. Since the observer can estimate the speed more accurately than the detection of the back electromotive force, a large speed feedback gain can be obtained and large damping can be applied.

〔The invention's effect〕

According to the system according to the first aspect, when estimating the speed from the detected position of the actuator, speed information can be obtained without using a differentiator, so that the influence of sensor noise can be reduced. This has the effect of improving the resolution. As a result, when damping is applied to the actuator, damping can be performed to a higher frequency. In addition, since the speed estimating means itself is configured to be mounted in the rotating drum, even when an output signal is generated and transmitted based on a small signal such as a sensor signal, the influence of noise is small and large. The signal can be transmitted to the outside as a level signal, whereby the influence of noise due to the transmission to the outside of the rotating drum can be reduced.

According to the second aspect of the present invention, by mounting the optical position detecting means, it is possible to detect the position without contact and with high accuracy, so that the absolute position of the actuator can be fixed or the position detected by the actuator can be converted into speed. It is possible to apply damping to the actuator by performing feedback. Also, by damping,
The tracking ability of the movable head when the track density is increased is improved.

According to the third aspect, by blinking the light emitting means, the position detection information from the light emitting means mounted on the actuator can be transmitted to the outside of the drum via the rotary transformer. This allows transmission without being affected by noise or the like, as compared with the case where a slip ring is used.

According to the fourth aspect, by using the electric drive actuator, the posture of the head does not change even if the head is displaced with a large amplitude as compared with a bimorph or the like, and the light-receiving element is attached to the movable part, thereby increasing the weight of the movable part. This makes it possible to perform highly accurate position detection without contact.

According to the fifth aspect, by using the electric drive actuator, the posture of the head does not change even if the head is displaced with a large amplitude as compared with a bimorph or the like, and by mounting a mirror on the movable part, an increase in the weight of the movable part is suppressed. Thus, non-contact and highly accurate position detection can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transfer function of an observer according to one embodiment of the present invention, FIG. 2 is a diagram showing frequency characteristics of an actuator according to one embodiment of the present invention, and FIG. 3 is tracking control according to one embodiment of the present invention. FIG. 4 is a configuration diagram of a magnetic sensor according to an embodiment of the present invention, FIG. 5 is a schematic diagram of a drum built-in substrate according to an embodiment of the present invention, and FIG. 6 is an embodiment of the present invention. 7, a signal transmission configuration diagram of the optical sensor according to an embodiment of the present invention, FIGS. 8 and 9 are open-loop characteristic diagrams of a tracking control system according to an embodiment of the present invention, FIG. 10 is a block diagram of a tracking control system using wobbling in one embodiment of the present invention, FIG. 11 is an observer circuit diagram in one embodiment of the present invention, and FIG. FIG. 13 is a configuration diagram of damping control of an actuator by a back electromotive force in one embodiment of the present invention, FIG. 13 is a pole arrangement diagram of a tracking control system in one embodiment of the present invention, FIG. FIGS. 16, 16 and 17 are external views showing an example of a bimorph, FIG. 18 is an operation diagram of the bimorph, FIG. 19 is a diagram showing a head tilt amount in a bimorph actuator, and FIG.
The figure shows the frequency characteristics of the bimorph actuator,
FIG. 21 is a configuration diagram of an electromagnetically driven actuator, FIG. 22 is a diagram showing frequency characteristics of the electromagnetically driven actuator, FIG.
FIG. 1 is a configuration diagram of tracking control by conventional wobbling. 101: Bimorph, 102: Sensor, 103: High impedance amplifier, 104, 109, 706, 716: Adder, 105:
Differentiator, 106: Low-pass filter, 107: Phase lead circuit, 108: Variable gain amplifier, 110: Drive amplifier, 11
1 …… Potentiometer, 112 …… Magnetic head, 113 ……
Video signal processing circuit 114 Head position control circuit 115
... frequency compensator, 116 ... converter reset signal generator, 201 ... magnet, 202 ... yoke, 203a ... gimbal spring, 203b ... leaf spring, 204 ... coil pobin, 205
…… Actuator coil, 206 …… Actuator, 2
07,406 Head amplifier, 208 Wobbling servo circuit, 209, 401, 717 Driver, 301 Actuator mechanism, 302 Actuator coil resistance, 303
Drive amplifier gain, 304, 305, 306, 307: actuator equivalent circuit, 308, 309: observer feedback gain, 310: velocity feedback gain, 402:
Observer (speed estimation means), 403: drum rotation control circuit, 404: pilot signal generation circuit, 405: modulation circuit, 407: tracking error generation circuit, 408: tracking control compensation circuit, 409: capstan Control circuit, 410: rotating drum, 411: slip ring, 412
…… Rotary transformer, 413… Position sensor (position detecting means), 501… Magnet holder, 502,5
05 …… Magnet, 503,506 …… Hall sensor, 504,607
…… Differential amplifier (sensor amplifier), 507 …… Substrate, 508…
… Drum mounting board, 601… Light emitting section, 602 …… Light receiving section, 60
3 ... Lens, 604 ... Outgoing lamp (squeezing), 605 ... Light emitting element, 606 ... Reflection mirror, 608 ... Detector circuit, 701 ...
… Band pass filter, 702… Synchronous detection circuit, 703 ……
Phase shifter, 704 …… Inverting amplifier, 705 …… Oscillator, 707 ……
Subtractor, 708, 713, 714 Low-pass filter, 709 Fixed head, 710 Phase locked loop (PLL) circuit, 711 Head amplifier, 712 Auto gain control (AGC) circuit, 715 Capstan phase control Circuit, 718 ... Capstan motor, 719 ... Linear track head, 720 ... Magnetic tape, 801,807,808,911,913 ...
… Condenser, 802,803,804,805,806,904,907,908,909
…… Differential amplifier, 901 …… Equivalent coil, 902,903 …… Current detection resistor, 910,912 …… Filter. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ────────────────────────────────────────────────── (5) Continuation of the front page (56) References JP-A-2-154315 (JP, A) JP-A-61-267919 (JP, A) JP-A-1-303631 (JP, A) JP-A 64-64 84482 (JP, A) JP-A-64-28563 (JP, A) JP-A-63-271728 (JP, A) JP-A-63-186574 (JP, A) JP-A-62-178186 (JP, A) Hirakai 1-1111306 (JP, U)

Claims (5)

(57) [Claims] 1. A tracking control system in a magnetic reproducing apparatus having a magnetic head and a magnetic tape for reproducing information, and a rotating drum for scanning the magnetic head on the magnetic tape, wherein the tracking control system is mounted on the rotating drum. An actuator for displacing the moved magnetic head in the tracking direction, position detection means of the actuator built in the actuator, and feedback of position information or speed information to the actuator based on a detection output from the position detection means. With feedback means for performing feedback, the feedback of the speed information, a position detection signal from the position detection means of the actuator, and a drive signal of the actuator as an input, an equivalent circuit simulating the mechanical characteristics of the actuator Speed estimating means is performed by using the speed information estimated by the tracking control system in a magnetic reproducing apparatus in which the speed estimating means is characterized by comprising configured on a circuit board that is fixed in the rotary drum. 2. The apparatus according to claim 1, wherein said position detecting means comprises an optical position detecting means comprising a light emitting means provided on a movable part and a fixed part of said actuator and a light receiving means divided into two. A tracking control system in the magnetic reproducing device according to claim 1. 3. The detected position information from the optical position detecting means is converted into an AC signal by blinking the light emitting means, and the position converted by the rotary transformer mounted on the rotary drum is converted into an AC signal. The tracking control system according to claim 2, wherein the detection signal is transmitted. 4. An actuator according to claim 1, wherein said actuator comprises a cylindrical electromagnetic drive portion comprising a coil and a permanent magnet; a plate-shaped magnetic head fixed portion fixed to said cylindrical movable member; 3. The tracking control system in a magnetic reproducing apparatus according to claim 2, wherein the tracking control system is constituted by an optical position detecting means having a light receiving element in a part. 5. The optical position detecting means according to claim 2, wherein said optical position detecting means comprises a reflecting mirror attached to a movable portion of said actuator, and a light emitting portion and a light receiving portion attached to a fixed side. Tracking control system in the magnetic reproducing device of the first embodiment.