JPH0411370A - Viscoelastic constant estimating method and disk device - Google Patents

Abstract

PURPOSE:To estimate an accurate viscoelastic constant by moving and operating a head on trial and estimating a damper constant in accordance with the attenuation ratio of the residual amplitude, the mass of an enclosure and a residual oscillation period, and estimating a spring constant in accordance with the mass of the enclosure and the residual oscillation period. CONSTITUTION:A head 3 which records or reproduces information on an information recording medium 1 like a disk is moved and operated on trial at a prescribed time, and the damper constant and the spring constant as the viscoelastic constants of an enclosure 8 and a viscoelastic member 9 are estimated in accordance with the residual oscillation of a position signal at this time. That is, the damper constant is estimated in accordance with the ratio of the first residual amplitude to the second residual amplitude of the position signal, the mass of the enclosure, and the residual oscillation period, and the spring constant is estimated in accordance with the mass of the enclosure and the residual oscillation period. Thus, the accurate viscoelastic constant is estimated.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a disk device for enriching and reproducing information, and in particular to a method for estimating the viscoelastic constant of a disk device casing, and a method for estimating the viscoelastic constant of the casing based on this method. The present invention relates to a control device for a disk drive equipped with an improved head positioning control device that eliminates the influence.

Conventional technology In order to record and reproduce information on a disk, which is a disk-shaped information recording medium, at high speed, it is necessary to move the head for recording and reproducing information to a desired track at high speed. (The reaction force of this force causes the casing that houses the carriage to vibrate, making it take longer to settle after seeking.)

This type of conventional disk device (Japanese Unexamined Patent Publication No. 6
As described in Publication No. 4-73579, it is equipped with an acceleration detection device that detects the acceleration in the theta direction in order to detect the vibration of the enclosure, and this allows the command signal to follow the residual vibration after the end of the seek. By adding this to the position control signal, the settling time is shortened.

FIG. 8 shows the configuration of a conventional magnetic disk device.

In FIG. 8, 1 is a magnetic disk that is an information storage medium, and 2 is a spindle motor that rotates the magnetic disk. 3 is a magnetic head for recording and reproducing information on the magnetic disk 1; 7 is a head feeding means consisting of a carriage 4 that holds the magnetic head; a coil 5 and a magnet 6 that generates a force for moving the carriage; This is a casing that houses the magnetic disk 1, spindle motor 2, and head feeding means 7. 9 is the case 8
19 is an acceleration detection device that detects the acceleration of the enclosure.
Reference numeral 10 denotes a position pressure detector, which generates a position signal X of the magnetic head 3 based on a servo signal taken out from the magnetic head 3. 11 is a drive controller that controls the entire device, such as generating the target track position Xr*f; 12 is a position control compensator;
The error signal ΔX, which is the difference between f and the position signal X, is subjected to, for example, PID (proportional integral differentiation) processing to generate a position control signal that allows stable position control at the target position.

A speed command generator 13 generates a movement command signal for moving the magnetic head to a target track. 14
is a vibration follow-up controller that generates a vibration follow-up signal from the detection output of the acceleration detection device 19.

15 is a signal synthesizing means for synthesizing the position control signal and the vibration tracking signal; 16 is a switch for switching the output of the signal synthesizing means and the movement command signal between position control and seek; 17 is an output of the switch 16; Depending coil 5
This is a drive circuit that sends current to the

Next, the operation of the conventional example will be explained. In FIG. 8, first, at the time of seek, the drive controller 11 reads the current track position from the position detector, calculates the number of remaining tracks to the target track, and calculates the number of remaining tracks to the target track.
Send this remaining track number to. The speed command generator 13 outputs a bundle movement command signal with an acceleration/deceleration time corresponding to the number of remaining tracks. At this time, the changeover switch 16 (friend) is switched to the b side by the drive controller 11 (switching signal not shown), and the movement command signal is transferred to the drive circuit 17.
A current is applied to the coil 5 to move the carriage 4 in the direction of the target track.

When the magnetic head 3 reaches the target track, the drive controller 11 switches the switch 16 to the a side and shifts from seek to position control.

During position control, a position control compensator performs, for example, +1 PID processing on the error signal △X, which is the difference between the position signal X detected by the position detector 10 and the target track position (r@f) output from the drive controller 11. 12 and sends its output to a drive circuit 17, thereby positioning the magnetic head 3 on the target track.

However, for example, in order to perform a high-speed seek, a large current must be passed through the coil 5 during the seek. When the carriage 4 moves due to this current, a reaction force is applied to the magnet 6, and that force is used to The vibration isolating rubber 9 supporting the housing 8, the magnetic disk, and the spindle motor vibrate at a natural vibration frequency ft determined by the mass of the entire inside of the housing, including the carriage, and the housing 8 and the housing 8 remain as residual vibrations even after the seek is completed.
The magnetic disk 1 fixed to the holder also vibrates. This anti-vibration rubber 9 is for suppressing external vibration, and has a natural vibration frequency f! is set sufficiently low for the frequency region where the compensation characteristics of the position control compensator are weak. Also, the damping ratio of the anti-vibration rubber is 0. A value of about 3 to 0.5 is common.
When a force is applied inside the magnetic disk device in a direction that causes off-track, the casing causes vibration at the natural vibration frequency ft. In addition, at this time, there is no problem with the vibration of the carriage 4 that holds the magnetic head 3. In general, the carriage 4 and the casing 8 are mechanically separated, so
Even if the housing 8 vibrates, the carriage 4 does not vibrate. Therefore, if this residual vibration is large, the magnetic head 3 will go off-track if only the position control is performed. Therefore, the residual vibration after the seek is extracted as acceleration by the acceleration detection device 19 attached to the housing 8, and the vibration tracking controller 14 generates a vibration tracking signal by cutting off the high range of the detected acceleration, and synthesizes this signal with the position control signal. L drive circuit 17
This prevents the magnetic head 3 from going off-track.

In this way, the conventional disk device is configured to be able to prevent off-track due to residual vibrations after high-speed seek by using an acceleration detection device.

Problems to be Solved by the Invention However, the conventional disk devices described above require an expensive acceleration detection device, which complicates the manufacturing process and increases costs.The present invention solves these conventional problems. The purpose of this invention is to provide an excellent disk device with a simple configuration that does not use an acceleration detector.

Means for Solving the Problems The present invention is based on the following method for estimating viscoelastic constants in order to achieve the above objects. - It consists of the following structure. In other words, the viscoelastic constant of the casing and the viscoelastic member is determined from the residual vibration of the position signal at a predetermined time when the head that records or reproduces information on a disk-shaped information recording medium is made a trial movement operation. The damper constant is estimated from the ratio of the first residual amplitude and the second residual amplitude of the position signal, the mass of the enclosure, and the residual vibration period.The spring constant is estimated from the mass of the enclosure and the residual vibration period. A head feeding means for moving a head for recording and reproducing information on a disc-shaped information storage medium to a desired track, and a casing for housing the information storage medium and the head feeding means. a position detection means for detecting the head position; a head movement signal generation means for sending a movement command signal necessary to move the head to a desired track; and a damper constant of the viscoelastic member using the elastic constant estimation method. A viscoelastic constant estimating means for estimating a spring constant; and a vibration tracking generating means for estimating the state of vibration of the casing by calculation from the movement command signal and generating a signal for causing the head to follow the vibration of the casing. It is something.

Due to the above-described configuration, the present invention has the following effects. In other words, the viscoelastic constant of the viscoelastic member is estimated each time it is used by performing a trial movement when the power is turned on.
The mechanical vibration state of the casing due to the reaction force of the force received when the head moves to a desired track is determined based on the electrical signal proportional to the reaction force applied to the casing and the estimated viscoelastic constant. A vibration follow-up signal generating means is provided which generates a vibration follow-up signal that is estimated by calculation and causes the head to follow the vibration of the enclosure.By adding this vibration follow-up signal to the positioning control in a feedforward manner, Stable stabilizing operation without off-track is possible when vibration conditions change.

Embodiment Below, a magnetic disk drive according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, the same parts as those shown in FIG. 8 are indicated by the same symbols. 1 is a magnetic disk that is an information storage medium; 2 is a spindle motor that rotates the magnetic disk; 3 is a magnetic head for recording and reproducing information on the magnetic disk l; 7 is a head feeding means comprising a carriage 4 for holding the magnetic head; a coil 5 and a magnet 6 for generating force for moving the carriage;
A casing 8 houses the magnetic disk 1, the spindle motor 2, and the head feeding means 7. Further, 9 is a vibration isolator L, which is a viscoelastic member that suppresses external vibration with respect to the casing 8, and 10 is a position detector, which receives a position signal X of the magnetic head 3 based on a servo signal taken out from the magnetic head 3. is generated.

Reference numeral 11 denotes a drive controller that controls the entire apparatus, such as generating a target track position Xxj; 12 a position control compensator; the target track position X; For example, for the error signal △X, which is the difference between t and the position signal
(integration, differentiation) processing to generate a position control signal that allows stable position control at the target position. A speed command generator 13 generates a movement command signal for moving the magnetic head to a target track. 18 is a detector for detecting the current flowing through the coil 5. A vibration tracking signal generator is a means for estimating the state of residual vibration of the housing 8 based on the amount of the current and generating a tracking signal for causing the head 3 to follow the residual vibration of the housing 8. 15 is a signal synthesizing means for synthesizing the position control signal and the tracking signal; 20 is a viscoelastic constant estimator for estimating the viscoelastic constant of the anti-vibration rubber, which is a viscoelastic member, from the position information output from the position detector 10; Reference numeral 16 designates a switch that switches between the output of the signal synthesizing means and the movement command signal during position control and seek time, and reference numeral 17 represents a drive circuit that sends a current to the coil 5 in accordance with the output of the switch 16.

Next, regarding the operation of the above embodiment, 1st @ 2nd @ 3rd plate
This will be explained using FIG. In FIG. 1, when searching, the drive controller 11 first takes in the current track position from the position detector 10, calculates the number of remaining tracks up to the target track, and sends this number of remaining tracks to the speed command generator 13. The speed command generator 13 outputs a bundle movement command signal with an acceleration/deceleration time corresponding to the number of remaining tracks.

At this time, since the selector switch 16 has been switched to the b side by the drive controller 11 (the switching signal is not shown), the movement command signal is sent to the drive circuit 17, which causes current to flow through the coil 5 and move the carriage 4 to the target track. move in the direction.

At this time, the switch 21 and the switch 22 are opened by the drive controller 11 (0N-O).
(FF signal not shown).

When the magnetic head 3 reaches the target track, the drive controller 11 (main switch 16 is switched to the a side) and shifts to position control. The magnetic head 3 is positioned on the target track by passing the error signal ΔX, which is the difference between the target position Furthermore, when shifting to position control, the switch 21 is short-circuited, and the outputs of the vibration follow-up signal generating means are combined by the adder 15, which is a signal combining means.

Next, regarding the vibration follow-up signal generator 18, the second plate No. 3 @
This will be explained using FIG.

First, when trying to move the head 3 at high speed, the coil 5
It is necessary to apply a large current to the magnet 6, and when the carriage 4 moves due to this current, a reaction force is applied to the magnet 6.

This force causes the main body 8C to vibrate at a natural vibration frequency ff determined by the mass of the entire inside of the body, including the vibration isolating rubber 9 supporting the body 8, the magnetic disk l, the spindle motor 2, the carriage 4, etc., and remains even after the seek is completed. The casing 8 and the magnetic disk 1 fixed to the casing 8 also vibrate as a result of the vibration.4 FIG. 2 is a vibration block diagram showing the vibration of the casing 8 as a simple model. In FIG. 2, 23 is a head movable R including the head 3, coil 5, and carriage 4, 24 is a mechanical spring component between the head movable part 23 and the casing 8, 2
5 is a mechanical damper component between the head movable part 23 and the casing 8; 26 is the entire inside of the casing fixed to the casing 8, including the magnetic disk 1, spindle motor 2, magnet 6; L-27 is the casing; 28 is a damper component of the vibration isolating rubber. During a seek, when a large current is passed through the coil 5 in order to move the head to a desired track, a force F. is applied to the head movable section 23.

At this time, the magnet 6 also receives a reaction force as a whole, and FT is applied in the opposite direction and the same magnitude as Fo. At this time, the mass of the head movable part 23 is M, and the displacement is X. , velocity is Vo, acceleration is α. , the damper constant between the head movable part 23 and the housing 8 is Do, and the spring constant is K.

The mass of the entire inside of the enclosure is M+, the displacement is Xt, the velocity is vt, the acceleration is αf, the damper constant of the vibration isolating rubber is Dr,
If the spring constant is +, the following equation of motion holds true.

M f conflict α t=Ft Dr 1
Vt −K t 9 XID−(v t −
v −) −K. (x+-x-) ・(1) Mo・α.

=F0-Do(v--vf)KO(xo-xc)-
(2) Here, in general, the mass M0 of the head movable part 23 is small, and it is displaced with a small force or no residual vibration occurs (also, the mass M+ of the entire inside of the casing is large, and the amount of displacement is small. (Vibration-proof rubber tends to cause residual vibration)
, % Therefore, since the interaction between the casing and the head movable portion 23 is small (the above equations (1) and (2) can be approximated as follows.

Mr・crt=Ft-Dr I vr-K
t・xr==(3)Mo”Uo=Fo−De
-Vo-Ko-Xo"" (4) (3) it Displacement Xr when the enclosure vibrates due to reaction force during seek,
Indicates the relationship between velocity vt and acceleration αt, (4)
The equation shows the relationship among the displacement Xo, velocity Ve, and acceleration α0 of the head movable part. For example, when a current as shown in FIG. 3(a) is passed through the coil 5 during L seek, the head movable part receives a force F as shown in FIG. 3(b). The magnetic disk 1 attached to the housing 8 is displaced as shown in Fig. 3(c).The casing also receives a force F as shown in Fig. 3(d). The vibration shown in e) is caused.This vibration becomes a position disturbance in position control, deteriorates the position control characteristics, and causes off-track.

Therefore, after the end of the seek, this off-track can be prevented by providing a signal to cause the head movable portion to follow the residual vibration of the casing. In other words, the force Fo required for the head movable part to follow the displacement xt of the casing
”11 In equation (4), ααfl vO−vfl
It is determined by the following equation (5), which is replaced with Xo-Xf.

Fo'=Mo ・α r+Do −v++Ko
- xr=(5) Therefore, if the vibration follow-up signal that generates the force determined by equation (5) above is applied to the positioning control in a wide forward manner, stable positioning operation without off-track can be performed.

Here, the force F++i that the enclosure receives during seek is approximately proportional to the current output from the drive circuit 17 during seek. 6-Fr” ao・Is (ao
is a proportionality constant, and 18 is a current value). Furthermore, if the current-voltage conversion constant of the drive circuit 17 is b [A/v], then the signal Svc that generates Fo' S, = F, '/(
ao-b). Therefore, the vibration follow-up signal generator 18 that generates a signal to suppress vibration during seek is the fourth
This can be realized with the configuration shown in the figure.

In FIG. 4, 40 is an A that converts the voltage Vl11 proportional to the current flowing through the coil 5 during seek into a digital value.
/D conversion edges 41 to 48 are multiplication edges 49 and 50 are adders 51 and 52 are integrators. Multiply the voltage proportional to ■8, which is the current value during seek, by the multiplier value (-ac>) of the multiplier 41 to find the force F that the casing receives. Add the outputs of the multipliers 43 and 44 to FT. The reciprocal of the mass of the box (
By multiplying by 1/Mr), the acceleration αr of the enclosure can be obtained. This acceleration αf is integrated by an integrator 51 to obtain the velocity vt, and by integrating the velocity Vf by the integrator 52, the displacement Xj of the enclosure can be obtained. Further, the velocity 1/f and the displacement Xt are multiplied by (-Df) and (-Kf), which are the multiplier values of 43.44, and are added to the force Ft by an adder 49. Also, the acceleration αf,
The velocity V+ and the displacement Xt are multiplied by Mo, Do, which are the multiplication values of the multipliers 45, 46, and 47, and are added together by the adder 50, so that the force F that causes the carriage 4 to follow the vibration of the enclosure 8 is obtained.・To seek ′, this power F・
By multiplying ' by the multiplication value (1/ao-b) of the multiplier 48, the signal Sv that generates the vibration following force F6'' can be obtained.

Based on the electric signal proportional to the force applied to the housing, the state of mechanical vibration of the housing due to the reaction force of the force received when the head moves to the desired track is calculated based on the electric signal proportional to the force applied to the housing. As a result, it is possible to generate a vibration follow-up signal that causes the head to follow the vibration of the enclosure, and this vibration follow-up signal 1 can be configured with two integrators, a multiplier, and an adder as shown in Figure 4. Therefore, it can be easily realized by digital calculation using a microcomputer.

However, vibration isolating rubber, which is a moderately damping viscoelastic material, has a problem in that its viscoelastic constants change due to temperature and aging, resulting in changes in the vibration conditions of the casing, such as the residual vibration frequency and damping rate. Therefore, each time the disk device is used, such as when the power is turned on, a trial movement is performed to estimate the change in the viscoelastic constant of the anti-vibration rubber, and the constant Df of the vibration follow-up signal generator is estimated.

It is possible to deal with the above problem by changing K in response to changes in the vibration state of the enclosure. We will explain the constant change of .

During the trial movement operation, the drive controller 11 sends a predetermined number of moving tracks to the speed command generator 13, and the speed command generator 13 generates a movement command signal corresponding to this number of moving tracks. This movement command signal causes the carriage 4 to reach a predetermined track, and then the position control is switched. This removal switch 21 is opened by the drive controller 11 and the vibration follow-up signal is cut off, so the position signal X vibrates as shown in FIG. From the vibration waveform of this position signal X, the viscoelastic constant can be estimated by the method shown below.

The viscoelastic constant estimating method and the operation of the viscoelastic constant estimator, which is the viscoelastic constant estimating means, will be described below with reference to FIG. Figure 5 shows the error signal for r/f (when position control is performed with respect to the vibration of the enclosure (Figure 3 (e)) when the vibration tracking signal is cut off. Therefore, after the position control The position error signal △X is almost proportional to the vibration waveform of the enclosure. Therefore, the time (t+, t2. ts, ta) and magnitude of the peak of the position error signal △X (△XI, △X2゜△ X 3. △X4) is measured and the vibration period Tl (T.

1/f'r), damping rate ζ, damper constant ri, and spring constant can be estimated from the following equations.

First, the mi vibration period Tf is found from TI-=ts-t+. Also, each peak value (△XI, △X2. △
X3, △X4) is △X1=△x@・exp(−ζ・ω,・tl)△X2−
△xa-exp (-ζ0ω1ゝt2) △ys=△X5-
eXp (-ζ・ω1-t3)△X4-△xs゛exp
(-ζ0ωj't4), so △X1/△X3-eXp (ζ・ωn(ta-t+))
exp (ζ・ω.・T,) =1+ζ・ωn' T I+...Approximately 8XI/△x3-1+ζ◆ω.・TI binding Also, from the relationship ζ-Df/(2・Mf・ωn), △XI/△xs= 1 + ((ω.・T'r-Dr)/
(2・Mt・ω1)) 1+ ((Tr−Dr)/ (2・M, )) Therefore, Df−((△x+/△X3)−1) (2・Mf)/Tf Also, even if (′L The first residual amplitude value △XI2, which is the value from the maximum to the minimum of the vibration waveform, and the second residual amplitude value △
Using X34, △x + / △X3 = △X12 / △
1, 2 =: △X1+△x2△) (8J-△X3+△X4 Both can be done, so D?=(△X12/△X34)・(2・M t)/
It is determined by T t. Further, Kf is determined by K t = M t + ωn M, (2·π/Tr) 2 .

In this way, the damper constant, which is the viscoelastic constant of the anti-vibration rubber, is converted into an error signal during position control.For example, the ratio of the first residual amplitude value to the second residual amplitude value, the mass of the enclosure, and the residual amplitude period are The spring constant can be estimated by four arithmetic operations based on the mass of the enclosure and the residual vibration period.The viscoelastic constant estimator can be easily realized using digital calculations using an A/D controller and a microcomputer. be able to.

After the viscoelastic constant is estimated as described above, the switch 22
is short-circuited, and the viscoelastic constant is sent to the vibration follow-up signal generator. By changing the constants of multipliers 43 and 44 in Figure 4, it is possible to compensate for changes in the vibration state of the enclosure due to the temperature of the anti-vibration rubber or changes over time. It is possible to generate a sufficient vibration tracking signal even if the

In this way, according to the above embodiment, for example, when the power is turned on, a trial movement is performed and the viscoelastic constant of the viscoelastic member is estimated each time it is used. The state of mechanical vibration of the enclosure is determined based on an electric signal proportional to the force applied to the enclosure and an estimated viscoelastic constant (2) Estimator from calculation Vibration follow-up signal generation means for causing the throat to follow this vibration equipped with
This generates a vibration tracking signal that causes the head to follow the vibration of the enclosure, and by adding this signal to positioning control in a feedforward manner, stable vibration control without off-tracking can be achieved even when the vibration state of the enclosure changes due to temperature, aging, etc. Positioning operations can be performed, and this also eliminates the need for expensive acceleration detection devices such as those used in conventional magnetic disk drives, which has the advantage of reducing the number of manufacturing steps and lowering costs.

Next, a viscoelastic constant estimating method for improving the accuracy of the viscoelastic constant estimator will be described.

The first method is to include the residual vibration frequency of the casing in the frequency components included in the movement command signal during the trial movement operation. For example (L, the residual vibration period of the enclosure at the time of assembly is stored in the memory in advance and a trial movement operation is performed. From now on, by using this updated residual vibration period T as the acceleration/deceleration time during the trial movement operation, the acceleration/deceleration time can be made almost equal to the residual vibration period of the casing, thereby efficiently performing the trial movement operation. The residual vibration of the enclosure can be increased.

The size of the position error signal during position control (△XI
, △X2. △xa, △X4) also becomes larger, and the accuracy of estimating the viscoelastic constant can be improved.

A second method is to change the control band for position control during normal operation and position control during trial movement operation. For example, as shown in FIG. 6, a first compensator 61 and a second compensator 62 are prepared in the position control compensator 12, and the drive controller 11 short-circuits the switch 63 during the trial movement operation.

Switch 64 is open L - position control is performed using the first compensator 61 ＼ Also, during normal operation, switch 63 is open and switch 64 is shorted L - position control is performed using the second compensator 62 . This second compensator 6
The control band during normal operation using 2 is generally determined from the resonance frequency of mechanical parts such as the head and carriage. In FIG. 7, the displacement suppression rate during normal operation is shown by a solid line. Positional fluctuations are suppressed for displacement disturbances, that is, vibrations of the enclosure, at frequencies below f1 at which the suppression rate is 0 dB.

Letting the residual vibration frequency of the enclosure be ft, the suppression rate is only Δa at the vibration frequency ft of the enclosure. Furthermore, by setting the control band of the first compensator 61 narrower and the control band of the second compensator 62, the position control band during the trial movement operation using the first compensator 61 becomes narrower, as shown in FIG. The displacement suppression rate is shown by the dotted line, and the suppression rate at the residual vibration frequency fr of the enclosure is lower (d). The accuracy of estimating the viscoelastic constant can be improved.

As a third method, by setting the cutoff frequency of the position control band during the trial movement operation to a frequency lower than the residual vibration frequency fr of the enclosure, the suppression rate is kept below zero, that is, the vibration displacement of the enclosure remains unchanged or is increased. It is also possible to estimate more accurate viscoelastic constants.

Effects of the Invention As is clear from the embodiments described above, the present invention allows a head for recording or reproducing information on a disk-shaped information recording medium to perform a trial movement operation at a predetermined time, and detects the residual vibration of the position signal at that time. and the damper constant and spring constant, which are the viscoelastic constants of the viscoelastic member, and the damper constant is the ratio of the first residual amplitude to the second residual amplitude of the position signal, the mass of the enclosure, and the residual vibration period. uses a viscoelastic constant estimation method such as estimating from the mass of the casing and the residual vibration period bX a casing that accommodates an information storage medium and a head feeding means; a viscoelastic member that attaches the casing to an external fixed end; and a casing that corresponds to the head position based on servo information read by the head from the information storage medium. position detection means for generating a position signal to move the head; position control means for positioning the head on a desired track based on the position signal; and head movement signal generation for sending a movement command signal necessary to move the head to the desired track. means, viscoelastic constant estimating means for estimating a damper constant and a spring constant of a viscoelastic member by the elastic constant estimating method, and estimating the state of vibration of the casing from the movement command signal by calculation; On the other hand, by providing vibration tracking generating means for generating a signal for causing the head to follow, and signal synthesizing means for synthesizing the outputs of the position control means and the vibration tracking signal generating means, expensive acceleration detection as in the conventional disk device is possible. This has the effect of reducing costs by not requiring any equipment and shortening the assembly process.

In addition, the acceleration/deceleration time during the trial movement operation is set to be approximately equal to the vibration period of the enclosure, and the position control means has two different control bands (compared to the normal position control band during the trial movement operation). It also has the effect that a more accurate viscoelastic constant can be estimated by lowering the band or by setting the control band during the trial movement lower than the natural frequency generated by the viscoelastic member and the casing.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the configuration of a magnetic disk device according to an embodiment of the present invention. FIG. 2 is a vibration block diagram modeling the vibration of the enclosure. FIG. Vibration explanatory diagram explaining the movement of the enclosure Figure 4 is the constituent block diagram of the vibration follow-up signal generator Figure 5 (Yo) Explanatory text explaining the viscoelastic constant estimation method for estimating the viscoelastic constant of a viscoelastic member The figure shows the internal blocks of the position control compensator. Figure 7 shows the displacement disturbance suppression ratio during position control. Figure 8 shows the schematic configuration of the conventional device. 1... Magnetic disk drive 3... Magnetic Head, 4°・Carriage, 8... Housing 9... Anti-vibration gong 4 10.
...Position detector 18...Vibration follow-up signal generator 20
... Viscoelastic constant estimation

Claims (8)

[Claims] (1) A head that records or reproduces information on a disc-shaped information recording medium is moved on a trial basis at a predetermined time, and from the residual vibration at that time, the damper constant, which is the viscoelastic constant of the casing and the viscoelastic member, is determined. A viscoelastic constant estimation method in which the spring constant is estimated from the damping ratio of the residual amplitude, the mass of the enclosure, and the residual vibration period, and the spring constant is estimated from the mass of the enclosure and the residual vibration period. (2) The viscoelasticity according to claim 1, wherein during a trial movement operation at a predetermined time, the acceleration/deceleration time of the trial operation is set to be approximately equal to the natural vibration period of the casing, and the viscoelastic constant is estimated. Constant estimation method. (3) During trial movement at a predetermined time,
2. The viscoelastic constant estimation method according to claim 1, wherein the position control band is narrowed and the residual vibration amplitude is increased to increase sensitivity and estimate the viscoelastic constant with high detection accuracy. (4) During a trial movement operation at a predetermined time,
The method according to claim 1, wherein the cut-off frequency of the position control band is lowered than the natural frequency generated by the viscoelastic member and the casing to increase the residual vibration amplitude, thereby increasing the sensitivity and estimating the viscoelastic constant with high detection sensitivity. Viscoelastic constant estimation method. (5) The viscoelastic constant estimation method according to claim 1, wherein the predetermined time is when the power is turned on. (6) The viscoelastic constant estimation method according to claim 1, wherein the damping ratio of the residual amplitude is a ratio between the first amplitude value and the second amplitude value of the residual amplitude. (7) Contains a disc-shaped information storage medium, a head for recording or reproducing information on the information storage medium, a head feeding means for moving the head to a desired track, and the information storage medium and the head feeding means. a viscoelastic member for attaching the housing to an external fixed end, and a position detection means for forming a position signal corresponding to the head position based on servo information read by the head from the information recording medium. a position control means for positioning the head on a desired track based on the position signal; a head movement signal generating means for sending out a movement command signal necessary to move the head to the desired track; viscoelastic constant estimating means for performing a trial movement operation in response to a command signal and estimating a damper constant and a spring constant of a viscoelastic member; and a viscoelastic constant estimating means for estimating a vibration state of the casing from the movement command signal by calculation, and calculating a vibration state of the casing from the movement command signal. A disk device comprising: vibration follow-up signal generation means for generating a signal for causing a head to follow; and signal synthesis means for synthesizing the outputs of the position control means and the vibration follow-up signal generation means. (8) The vibration follow-up signal generating means comprises at least two integrators, a multiplier whose multiplication value can be changed, and an adder,
8. The disk device according to claim 7, wherein the multiplication value of the multiplier is changed in accordance with the estimated value of the viscoelastic constant by the viscoelastic constant estimating means.