JP2005293839A - Storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute loading/unloading control by detecting an accurate speed from the counter electromotive force of a motor regarding a storage device for head loading/unloading control to retreat a head for reading from a storage medium to the outside of the storage medium. <P>SOLUTION: The storage device is provided with a storage medium (6), a head (4), an actuator (3), a control circuit (19), and a lamp member (11). In this case, a speed is controlled by using a speed detected by the counter electromotive voltage of an actuator (3) for unloading/loading control for retreating the head (4) to the outside of the storage medium (6). A speed correction coefficient for converting a counter electromotive voltage into a speed is corrected by a moving speed obtained from a demodulation position read from the storage medium by the head. Thus, an accurate speed is obtained even when the counter electromotive voltage is detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a storage device for detecting the speed of an actuator from the back electromotive force of the actuator, and in particular, when a head for reading the storage medium is unnecessary (when an access command does not arrive for a predetermined time), the storage medium The present invention relates to a storage device for performing an unload operation for saving outside.

  Storage devices having a head for reading a storage medium are widely used. For example, a magnetic disk drive used as a computer storage device includes a magnetic disk, a head for reading / writing the magnetic disk, and a VCM (voice coil motor) for positioning the head on a track of the magnetic disk. Yes. The recording density of this disk drive has increased dramatically. Small disk drives for this purpose have been developed. A small disk drive is portable by itself and is also used as an external storage device of a portable handheld computer.

  The hard disk device includes a magnetic disk, a magnetic head, a VCM actuator, and a flexure (suspension). In this hard disk device, with the recent increase in the density of magnetic disks, the flying height of the magnetic head with respect to the magnetic disk has decreased. For this reason, even with slight vibrations, the magnetic head and the magnetic disk come into contact with each other and are damaged.

  In order to prevent this, a hard disk device has been proposed in which a ramp member is provided at a position outside the magnetic disk, and when the head is not in operation, the head is retracted to the position of the ramp member (this is called an unload operation). (For example, JP-A-6-60578).

  Recent hard disk devices and electronic devices (computers, etc.) incorporating the hard disk devices are being carried around. For this reason, the hard disk device is used in an environment that is susceptible to vibration from the outside. In addition, since the electronic device is driven by a battery, the power supply capacity is limited. For this reason, it is desired to reduce power consumption.

  For this reason, in such a conventional storage device, the continuous time when the access (input / output command) does not arrive continuously is counted, and when the continuous time reaches a predetermined time, the aforementioned unloading operation is performed, and the head is connected to the magnetic disk. Evacuation was done from. In this method, the head is retracted from the magnetic disk when there is no access for a predetermined time, so that damage can be prevented even if vibration is applied from the outside. Further, since it is mechanically supported by the lamp member, it is not necessary to pass a driving current through the VCM, so that power consumption can be reduced. Further, when access is reached, the head can be loaded only during use by returning the head from the ramp member to the magnetic disk (this is called loading).

  However, the prior art has the following problems.

  (1) In the prior art, speed control was not performed during loading / unloading. In such a storage device, the head reads the servo information (position information) recorded on the disk and detects the speed and position, but the head moves away from the disk at the time of loading / unloading. Cannot read and cannot detect speed. For this reason, the head or the like collides with the ramp member during unloading, and the head collides with the disk during loading. In order to alleviate this collision, if the moving speed during loading / unloading is made low, there is a problem that high-speed loading / unloading operations cannot be performed.

  (2) Furthermore, in order to convert the back electromotive force of the motor (actuator) into a speed, it is necessary to set a correction coefficient appropriately. However, since this correction coefficient changes depending on the apparatus and temperature, there is a problem that it is difficult to set an appropriate correction coefficient.

  An object of the present invention is to provide an actuator control method and a storage device for controlling the speed of an actuator even when the head at the time of loading / unloading cannot read the storage medium.

  Another object of the present invention is to provide an actuator control method and a storage device for obtaining an appropriate correction coefficient for converting a back electromotive voltage of a motor (actuator) into a speed.

  To achieve this object, a storage device according to the present invention is provided with a head for reading at least a storage medium, an actuator for positioning the head at a predetermined position of the storage medium, and a position outside the storage medium, and supporting the head. A ramp member, a counter electromotive voltage detection circuit for detecting a counter electromotive voltage of the actuator, storage means for storing a correction coefficient for converting the counter electromotive voltage into the moving speed, and the head from the storage medium. The load is unloaded at the position of the ramp member, and the head is loaded from the ramp member onto the storage medium. At the time of unloading or loading, the correction coefficient of the storage means is calculated from the output of the back electromotive voltage detection circuit. And a control means for detecting the moving speed of the actuator and controlling the speed of the actuator. The moving speed of the actuator which is calculated from the position information of the storage medium in which de is read, and a moving speed of the actuator which is calculated from the counter electromotive voltage, to calibrate the correction factor.

  In the present invention, it is preferable that the control means moves the head over the storage medium at the start of unloading, and determines the moving speed of the actuator from the positional information of the storage medium read by the head. The moving speed of the actuator is calculated from the back electromotive force, and the correction coefficient is calibrated from the calculated moving speed.

  In the present invention, it is preferable that the control means performs speed control during the unloading using the calibrated correction coefficient.

  In the present invention, it is preferable that the control unit moves the head from the first position to the second position of the storage medium, and the position of the storage medium read by the head for each sample. The moving speed of the actuator is calculated from information, the moving speed of the actuator is calculated from the back electromotive force, the correction coefficient is calculated from the calculated moving speeds, and the calculated correction coefficient of a plurality of samples is calculated. The correction coefficient is calibrated by the average value of.

  In the present invention, it is preferable that the control means is a ratio of a movement speed of the actuator calculated from position information of the storage medium read by the head and a movement speed of the actuator calculated from the counter electromotive voltage. From the above, the correction coefficient is calibrated.

  In the present invention, in order to calibrate the correction coefficient so that the moving speed detected from the back electromotive voltage matches the moving speed of the actuator calculated from the position information of the storage medium, the back electromotive voltage is converted into an accurate moving speed. be able to. Furthermore, when the correction coefficient is calibrated during unloading, measurement can be performed without requiring a special measurement operation. For this reason, the waiting time of the storage device can be reduced.

  Hereinafter, the present invention will be described by dividing it into a storage device, a load / unload process, a speed control method thereof, and a load / unload process including calibration.

··Storage device··
FIG. 1 is a top view of a storage device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the storage device, FIGS. 3 and 4 are configuration diagrams of the lamp member, and FIG. It is a block diagram. In this example, a hard disk device is taken as an example of the storage device.

  As shown in FIGS. 1 and 2, the magnetic disk 6 is configured by providing a magnetic recording layer on a 2.5-inch substrate (disc). Three magnetic disks 6 are provided in the drive. The spindle motor 5 supports the magnetic disk 6 and rotates. The magnetic head 4 is provided in the actuator. The actuator includes a rotary VCM (voice coil motor) 3, an arm 8, and a flexure (suspension) 9. A magnetic head 4 is attached to the tip of the flexure 9.

  The magnetic head 4 reads data from the magnetic disk 6 and writes data. The actuator 3 positions the magnetic head 4 on a desired track of the magnetic disk 6. The actuator 3 and the spindle motor 5 are provided on the drive base 2. The cover 1 covers the drive base 2 and isolates the inside of the drive from the outside. The printed board 7 is provided under the drive base 2 and mounts a drive control circuit. The connector 10 is provided under the drive base 2 and connects the control circuit and the outside.

  This drive is small and has a width of 90 mm, a length of 63 mm, a width of about 10 mm. Therefore, it is used as a built-in disk of a notebook personal computer.

  As shown in FIG. 1, a ramp member 11 is provided outside the magnetic disk 6 in the drive base 2. The ramp member 11 is formed of a synthetic resin and supports the head when the head is unloaded. As shown in FIG. 4, a lift tab 12 is provided at the tip of the suspension 9 that supports the magnetic head 4. The lift tab 12 contacts the ramp member 11. As shown in FIG. 3, the ramp member 11 has a slope 11-1 and a recess 11-2. The slope 11-1 is provided to smoothly move the head 4 from the magnetic disk 6 to the ramp member 11. The recess 11-2 is provided to mechanically hold the lift tab 12 during unloading.

  FIG. 5 is a block diagram of a control circuit provided in the printed board 7 and the drive. An HDC (Hard Disk Controller) 18 generates a control signal inside the magnetic disk device for controlling interface with the host CPU such as exchange of various commands of the host CPU, exchange of data, etc., and recording / reproducing format on the magnetic disk medium. Etc. The buffer 17 is used for temporary storage of write data from the host CPU and temporary storage of read data from the magnetic disk medium.

  The MCU (microcontroller) 19 is configured by a microprocessor (MPU) or the like. The MCU (hereinafter referred to as MPU) 19 performs servo control for positioning the magnetic head. The MPU 19 executes a program stored in the memory, recognizes the position signal from the servo demodulation circuit 16, controls the VCM control current of the VCM drive circuit 13, and controls the drive current of the SPM drive circuit 14.

  The VCM drive circuit 13 is configured by a power amplifier or the like for causing a drive current to flow through a VCM (voice coil motor) 3. The SPM drive circuit 14 is composed of a power amplifier for supplying a drive current to a spindle motor (SPM) 5 that rotates a magnetic disk.

  The read channel 15 is a circuit for performing recording and reproduction. The read channel 15 has a modulation circuit for recording write data from the host CPU on the magnetic disk medium 6, a parallel-serial conversion circuit, a demodulation circuit for reproducing data from the magnetic disk medium 6, a serial-parallel conversion circuit, and the like. . The servo demodulation circuit 16 is a circuit that demodulates the servo pattern recorded on the magnetic disk medium 6, and includes a peak hold circuit, an integration circuit, and the like.

  Although not shown, the drive HDA is provided with a head IC that includes a write amplifier that supplies a recording current to the magnetic head 4 and a preamplifier that amplifies the reproduction voltage from the magnetic head 4.

Here, a magnetic disk device is described as an example of a storage device, but an optical disk device such as a DVD or MO, a magnetic card device, an optical card device, or the like may be used, and is shown as a readable / writable device. However, a read-only device (reproducing device) may be used.
・ ・ Load / Unload processing ・ ・
FIG. 6 is a circuit diagram of a VCM back electromotive voltage detection circuit provided in the VCM drive circuit of FIG.

  As shown in FIG. 6, the coil of the VCM 3 has a resistance Rv and an inductance L. A current sense resistor Rs is connected to the inductance L. In parallel with this, a resistor R1 for detecting a back electromotive voltage corresponding to the resistor Rs and a resistor R2 for detecting a back electromotive voltage corresponding to the resistor Rv are provided. The amplifier AMP subtracts the midpoint potential of the resistors R1 and R2 from the potential of the resistor Rs. The differential amplifier D-AMP takes the difference between the potential of the VCM resistor Rv and the output potential of the amplifier AMP. Here, when the gain of the differential amplifier D-AMP is “G”, the voltage across the VCM is “A”, and the VCM current is Iv, the detection voltage Va is expressed by the following equation.

Va = G (Iv.Rs.R2 / R1-A) (1)
Here, when the back electromotive voltage of VCM is Vb, the both-end voltage A is expressed by the following equation.

A = Iv · Rv + Vb (2)
Substituting this into equation (1) yields the following equation (3).

Va = G [Iv.Rs.R2 / R1- (Iv.Rv + Vb)]
Va = G [(Rs · R2 / R1−Rv) Iv−Vb] (3)
From the equation (3), the VCM current Iv is a drive instruction current value and is known, so that the counter electromotive voltage can be detected from the detection voltage Va. Since the VCM back electromotive voltage is obtained by the product of the force constant and the speed, the speed can be detected from the detected VCM back electromotive voltage.

  That is, the actual speed vr of the motor is obtained by the following equation (4).

vr = Ke / Vb = Ke / (K / Iv−Va) (4)
Here, Ke is a correction coefficient obtained from the force constant, and K is (Rs · R2 / R1−Rv) in the equation (3). However, the gain G is “1”.

  Processing for detecting the speed from the back electromotive voltage of the VCM and loading / unloading it will be described with reference to FIGS.

  FIG. 7 is an unload processing flowchart.

  (S1) Upon receiving the unload command, the MPU 19 (see FIG. 5) seeks the VCM 3 to a specific cylinder (near the ramp member 11 in FIG. 3) of the magnetic disk 6. At this time, the MPU 19 detects the current position and current speed based on the servo information of the magnetic disk 6 read by the head 4 and controls the position.

  (S2) Next, the MPU 19 drives the VCM 3 to the outer stopper position. At this time, the MPU 19 detects the detection voltage value Va of the VCM back electromotive voltage detection circuit 13-1 at a predetermined sample time, and calculates the actual speed by the above-described equation (4). Then, the VCM drive current Iv is calculated based on the difference between the target speed and the actual speed, and the speed of the VCM 3 is controlled via the VCM drive circuit 13.

  As a result, as shown by an arrow F in FIG. 3, the lift tab 12 is guided by the slope 11-1 of the ramp member 11, and is moved toward the recess 11-2, and the recess 11-2 (lamp parking area). Is housed in. Therefore, the head 4 is held at a position outside the magnetic disk 6 as indicated by a position P0 in FIG.

  At this position, since the head 4 does not face the magnetic disk 6, the magnetic head 4 and the magnetic disk 6 do not collide even when an impact is applied. Further, since the magnetic head 4 is mechanically held, the magnetic head 4 is not vibrated by an impact. Thereby, impact durability can be improved. Further, since it is mechanically held, it is not necessary to pass a current through the VCM 3. Thereby, power consumption can be reduced.

  Furthermore, in the ultra-small memory device, since the components are arranged with high density, it is difficult to dissipate heat. At this position, no current flows through the VCM 3, so that the temperature rise of the apparatus can be prevented.

  Here, the meaning of speed control will be described. At the time of ramp unloading, the magnetic head 4 is separated from the magnetic disk 6, so that the magnetic head 4 cannot read the servo information of the magnetic disk 6. For this reason, the speed cannot be obtained from the magnetic head 4.

  On the other hand, the magnetic head 4 floats from the magnetic disk 6. However, since the flying height is small, an attractive force is generated between the magnetic head 4 and the magnetic disk 6. Therefore, in order to move the magnetic head 4 away from the magnetic disk 6 and climb the slope 11-1 of the ramp member 11, it is necessary to drive the VCM 3 at a predetermined speed or higher. On the other hand, if the speed is increased too much, the impact when the VCM 3 collides with the outer stopper is increased, and the life of the mechanical parts is shortened. For this reason, the magnetic head 4 uses the counter electromotive voltage of the VCM to control the speed even during ramp unloading when the servo information of the magnetic disk 6 cannot be read.

  Next, the loading process will be described with reference to FIG.

  (S3) Upon receiving the ramp load command, the MPU 19 drives the head 4 in the direction of the magnetic disk 6 by the VCM 3. First, the MPU 19 passes a certain launch current through the VCM 3 in order to get over the recess 11-2 of the ramp member 11. Thereby, the lift tab 12 gets over the dent 11-2 of the ramp member 11.

  (S4) Next, the MPU 19 detects the detection voltage value Va of the VCM back electromotive voltage detection circuit 13-1 at a predetermined sample time, and calculates the actual speed by the above-described equation (4). Then, the VCM drive current Iv is calculated based on the difference between the target speed and the actual speed, and the speed of the VCM 3 is controlled via the VCM drive circuit 13. As a result, the lift tab 12 moves in the direction of the magnetic disk 6 (the R direction in FIG. 3) by swinging the slope 11-1 from the recess 11-2 of the ramp member 11.

  (S5) The MPU 19 stops the speed control when a predetermined time has elapsed from the start of the speed control, shifts to the position control based on the servo information of the magnetic disk 6 and ends. That is, since the distance from the ramp member 11 to the return position of the magnetic disk 6 is known and the target speed is also known, the head has reached the return position of the magnetic disk 6 from the ramp member 11. Can be detected by time.

  As a result, the magnetic head 4 returns to the magnetic disk 6. For this reason, the magnetic head 6 can be read / written by the magnetic head 4. Note that the position P1 in FIG. 1 is the position of the actuator when the drive is assembled.

  Here, since the speed is controlled during ramp loading, the head 4 can be prevented from colliding with the magnetic disk 6. Further, the magnetic head 4 can control the speed by using the back electromotive force of the VCM even during ramp loading when the servo information of the magnetic disk 6 cannot be read.

・ ・ Speed control method ・ ・
Next, a method capable of executing speed detection based on the back electromotive voltage of the VCM in a short sample period will be described. FIG. 9 is an explanatory diagram of the voltage across the VCM coil, FIG. 10 is an explanatory diagram of a conventional VCM current update timing, FIG. 11 is a speed detection processing flow diagram according to the present invention, and FIG. 12 is a VCM transient for FIG. FIG. 13 is an explanatory diagram of the response model, FIG. 13 is an explanatory diagram of the sample interval of FIG. 11, and FIG. 14 is an explanatory diagram of the VCM current update timing according to the present invention.

  Since the VCM has an inductance, a transient response occurs when a step input (update of the current instruction value) is given. Therefore, as shown in FIG. 9, the above-described voltage A across the coil has the voltage value B (= Iv · Rv) by the VCM command current Iv, the VCM back electromotive voltage C (Vb), and the transient response component of the VCM inductance. It is expressed as the sum of D. That is, as shown in FIG. 10, the voltage A across the coil has a transient response immediately after the current update of the VCM, and after a certain time, the transient response has settled. The detection voltage Va of the VCM counter electromotive voltage detection circuit 13-1 in FIG. 6 also shows a similar transient response.

  That is, if the speed is detected (back electromotive voltage is detected) during the transient response of the VCM due to the inductance, the error is large. In order to eliminate this error, it was necessary to wait until the transient response of the inductance had settled down to some extent. Therefore, conventionally, as shown in FIG. 10, after the VCM current is updated, the error is large within a period T0 until the transient response of the inductance falls to some extent, so that the back electromotive voltage of the VCM cannot be detected. . Therefore, the VCM current update timing interval cannot be shortened from T0. As a result, since high-speed speed detection and current update cannot be performed, even if speed control is performed, the speed error is large and control to the target speed is not possible.

  In this embodiment, in order to shorten the interval of the VCM current update timing, an accurate VCM back electromotive voltage can be detected even during the transient response of the VCM. For this reason, the transient response of the VCM is modeled in advance, the transient response voltage value of the VCM is calculated, and thereby the detection voltage is corrected.

  FIG. 12A is a block diagram of the VCM driving circuit. As shown in FIG. 12A, the VCM 3 is expressed by a resistance R (Rv) and an inductance L. Rs is the aforementioned sense resistor. The first differential amplifier DA detects the VCM current Id from the voltage across the resistor Rs. The second differential amplifier DM controls the output voltage of the power amplifier PA based on the difference between the command current value Iv and the detected current value Id.

  To obtain a model of the VCM transient response, a unit step input is given to this drive circuit. As shown in FIG. 12B, the command current value Iv of the unit step (“1”) is given to the drive circuit. At each time t, the voltage value A across the VCM coil is sampled, and the sample value Sn (n = 1, 2˜) is stored in the memory. Thereby, the transient response model can be developed in the memory.

  Next, speed detection processing using this transient response model will be described with reference to FIG.

  (S10) When updating the VCM current, the MPU 19 waits for a time T.

  (S11) After the lapse of time T, the MPU 19 samples the detection voltage Va of the VCM back electromotive voltage detection circuit 13-1.

  (S12) The MPU 19 calculates the transient response voltage value D after the time T from the transient response model of the memory. That is, the sample value after the time T is extracted from the sample value in the memory, and the transient response voltage value D after the time T is calculated by multiplying the indicated current value.

  (S13) The MPU 19 subtracts the transient response voltage value D from the detected voltage value Va to calculate the corrected detected voltage value Va.

  (S14) The MPU 19 calculates the actual speed vr by substituting the corrected detection voltage value Va into the above-described equation (4).

  The MPU 19 calculates a control amount (VCM current instruction value) from the speed error between the target speed and the actual speed, and updates the VCM current.

  In this way, the transient response voltage value D with respect to the current command value is calculated and subtracted from the detected voltage. Therefore, as shown in FIG. 13, after the VCM current is updated, the VCM back electromotive voltage is detected during the VCM transient response. However, accurate speed can be detected.

  Therefore, as shown in FIG. 14, the detection interval of the VCM back electromotive voltage and the VCM current update timing interval can be shortened as T1. As a result, high-speed speed detection and current update are possible, and even if speed control is performed, the speed error is small and control can be performed to the target speed. In this example, the update cycle T1 is 1/3 of the cycle T0 in FIG. 10, and triple speed control can be performed.

  In the above example, the VCM transient response voltage included in the output voltage Va of the back electromotive voltage detection circuit is corrected. However, as shown in FIG. 9, it can also be used to correct the voltage value across the VCM. In other words, in the case of a circuit configuration in which the back-EMF voltage detection circuit is not provided, the voltage value at both ends of the VCM is detected from the VCM drive circuit and the actual speed is calculated, the VCM transient response voltage is subtracted from the voltage value at both ends of the VCM. After correcting the value, an accurate VCM back electromotive force voltage can be detected by subtracting the voltage value B corresponding to the VCM command current value.

Furthermore, this speed detection method can be executed even when not loading / unloading or without a load / unload mechanism. Furthermore, the present invention can also be applied to speed detection of motors other than the hard disk VCM for speed control.
・ ・ Load / unload processing including calibration ・ ・
Next, in the aforementioned equation (4), the speed offset coefficient K is defined by a resistance value, that is, (Rs · R2 / R1−Rv). Ideally, the speed offset coefficient K is preferably “0”, but the speed offset coefficient K is determined by the resistance value of each VCM back electromotive voltage detection circuit 13-1 and the VCM back electromotive voltage detection circuit 13-1 depending on the temperature change. It varies depending on the resistance value of VCM. For this reason, it is necessary to calibrate the speed offset coefficient K.

  FIG. 15 is a flowchart of the load process including the calibration according to the present invention, and FIG. 16 is an explanatory diagram of the calibration operation.

  (S20) Upon receiving the ramp load command, the MPU 19 supplies the first pressing current I1 in the outer direction to the VCM 3. As described above, at the unload (parking area) position, the VCM 3 is positioned at the outer stopper thereof, so that even if a pressing current is supplied, the VCM 3 does not move in the outer direction. Then, the MPU 19 reads the detection voltage V1 of the VCM back electromotive voltage detection circuit 13-1 at this time.

  (S21) Next, the MPU 19 supplies the second pressing current I2 in the outer direction to the VCM 3. The second pressing current value I2 is different from the first pressing current value I1. As described above, at the unload (parking area) position, the VCM 3 is positioned at the outer stopper thereof, so that even if a pressing current is supplied, the VCM 3 does not move in the outer direction. Then, the MPU 19 reads the detection voltage V2 of the VCM back electromotive voltage detection circuit 13-1 at this time.

  (S22) Thus, as shown in FIG. 16, when the drive current Iv is supplied to the VCM 3 while the VCM 3 is fixed, the speed offset coefficient K is not zero although the speed is zero. It will not be zero. Therefore, the speed offset coefficient is obtained from the detection voltages V1 and V2 and the current values I1 and I2.

  From the above equation (3), V1 = K · I1−Vb and V2 = K · I2−Vb. Therefore, the speed offset coefficient K is obtained by calculating the following equation (6).

K = (V2-V1) / (I2-I1) (6)
(S23) Thus, after the speed offset coefficient K is calibrated, the MPU 19 drives the head 4 in the direction of the magnetic disk 6 by the VCM 3. First, the MPU 19 passes a constant driving current in the inner direction to the VCM 3 in order to get over the recess 11-2 of the ramp member 11. Thereby, the lift tab 12 gets over the dent 11-2 of the ramp member 11.

  (S24) Next, the MPU 19 detects the detection voltage value Va of the VCM back electromotive voltage detection circuit 13-1 at a predetermined sample time, and uses the calibrated speed offset coefficient K and the above equation (4). Calculate the actual speed. Then, the VCM drive current Iv is calculated based on the difference between the target speed and the actual speed, and the speed of the VCM 3 is controlled via the VCM drive circuit 13. As a result, the lift tab 12 slides on the slope 11-1 from the recess 11-2 of the ramp member 11 and moves in the direction of the magnetic disk 6 (R direction in FIG. 3).

  (S25) When a predetermined time has elapsed from the start of speed control, the MPU 19 stops speed control, shifts to the position control based on the servo information of the magnetic disk 6 and ends. That is, since the distance from the ramp member 11 to the return position of the magnetic disk 6 is known and the target speed is also known, the head has reached the return position of the magnetic disk 6 from the ramp member 11. Can be detected by time.

  As a result, the magnetic head 4 returns to the magnetic disk 6. For this reason, the magnetic head 6 can be read / written by the magnetic head 4.

  As described above, in a state where the VCM 3 is fixed, the velocity offset coefficient K can be calibrated by supplying a current to the VCM 3 and obtaining the detection voltage. Further, in this embodiment, since it is performed at the start of loading, speed detection for speed control during loading becomes accurate. That is, even if the resistance value changes due to temperature or the like and the speed offset coefficient changes, calibration can be performed before the load operation. Further, since the VCM is executed in the unload area while being fixed to the outer stopper, no special fixing operation is required. For this reason, calibration processing can be performed in a short time.

  This calibration method can be performed even when not loading or without a load / unload mechanism. For example, a calibration process can be provided separately from the load process, and the above-described calibration process can be executed by fixing the VCM 3 to the outer stopper or the inner stopper.

  Similarly, the present invention can be applied to speed detection of motors for speed control other than hard disk VCM. Further, the following modification is possible as a method for obtaining the above-described speed offset coefficient. First, the current value I1 may be “0”. Second, when the back electromotive voltage Vb when the VCM is fixed is constant (0), the speed offset value K can be calculated by detecting the voltage once. Third, the above-described calibration process can be performed a plurality of times, and the average value can be adopted as the speed offset value K.

  Next, in the aforementioned equation (4), the speed correction coefficient Ke is determined by the force constant Bl of the VCM 3. However, the force constant Bl of the VCM 3 changes with temperature changes. For this reason, it is necessary to calibrate the speed correction coefficient Ke.

FIG. 17 is an unload processing flowchart including such calibration according to the present invention, and FIG. 18 is an explanatory diagram of the calibration operation.
(S30) Upon receiving the unload command, the MPU 19 first executes calibration. That is, the magnetic head 4 is moved to the first cylinder position of the magnetic disk 6 by the VCM 3. Next, the movement of the magnetic head 4 to the second cylinder position of the magnetic disk 6 is started by the VCM 3.

  (S31) The MPU 19 detects the position of the VCM 3 from the servo information read by the magnetic head 4 for each sample, and calculates the movement amount L at one sampling interval. That is, the movement amount L can be obtained by subtracting the detection position at the previous sample from the detection position at the current sample. Then, the moving speed vs obtained from the servo information is calculated from “L / S”. Note that S is a sampling interval.

  (S32) The MPU 19 detects the detection voltage Va of the VCM back electromotive voltage detection circuit 13-1, and calculates the moving speed vr obtained from the VCM back electromotive voltage according to the above-described equation (4).

  (S33) Next, the MPU 19 calculates the gain error Er from the speed ratio (vs / vr). As shown in FIG. 18, the speed vs calculated from the position information is from the servo information and does not change with temperature. Based on this, the speed correction coefficient Ke is corrected. That is, the speed correction coefficient Ke is obtained by “Ke + Er”. This speed correction coefficient is stored.

  (S34) Next, the MPU 19 determines whether or not the second cylinder position described above has been reached. If not, the process returns to step S31.

  (S35) When the MPU 19 determines that the second cylinder position has been reached, first, the speed correction coefficient Ke obtained for each sample is added and divided by the number of samples n to obtain an average value. As shown in FIG. 18, since the detection speeds vs and vr change, average values are adopted. This average value is stored as a speed correction coefficient Ke.

  (S36) Next, the MPU 19 drives the VCM 3 to the outer stopper position. The MPU 19 detects the detection voltage value Va of the VCM back electromotive voltage detection circuit 13-1 at a predetermined sample time, and calculates the actual speed based on the stored speed correction coefficient Ke and the above-described equation (4). Then, the VCM drive current Iv is calculated based on the difference between the target speed and the actual speed, and the speed of the VCM 3 is controlled via the VCM drive circuit 13.

  As a result, as shown by the arrow F in FIG. 3, the lift tab 12 is guided by the slope 11-1 of the ramp member 11, and is moved toward the recess 11-2.

  (S37) When the arrival time elapses from the speed control start time, the MPU 19 stops the speed control. That is, since the distance from the second cylinder position of the magnetic disk 6 to the recess 11-2 is known and the target speed is also known, the head has reached the recess 11-2 of the ramp member 11. This can be detected by time. Thereby, the lift tab 12 is accommodated in the dent 11-2 (lamp parking area). Therefore, the head 4 is held at a position outside the magnetic disk 6 as indicated by a position P0 in FIG.

  Thus, the speed correction coefficient Ke can be calibrated to measure the moving speed obtained from the position information of the magnetic disk 6 and the moving speed obtained from the back electromotive voltage of the VCM 3. Further, in this embodiment, since the unloading is started, speed detection for speed control at the time of unloading becomes accurate. In other words, even if the VCM force constant changes due to temperature or the like and the speed correction coefficient changes, it can be calibrated before the unload operation. Furthermore, since it is performed during on-track, no special operation is required. For this reason, calibration processing can be performed in a short time.

  This calibration method can be executed even when unloading or without a load / unload mechanism. For example, a calibration process can be provided separately from the unload process, and the above-described calibration process can be executed by moving the VCM 3 by a cylinder. Similarly, the present invention can be applied to speed detection of motors for speed control other than hard disk VCM.

  In addition to the above-described embodiments, the present invention can be modified as follows.

  (1) In the above embodiment, the head unload control of the magnetic disk drive has been described. However, the present invention can be applied to other storage devices such as the head unload control of the optical disk drive.

  (2) Similarly, lamp members having other shapes can be used.

  As mentioned above, although this invention was demonstrated by embodiment, a various deformation | transformation is possible within the range of the main point of this invention, and these are not excluded from the scope of the present invention.

  As described above, since the head detects the speed from the back electromotive voltage of the actuator at the time of loading / unloading where the position information of the storage medium cannot be read, the speed can be controlled even at the time of loading / unloading. Therefore, the load / unload operation can be executed smoothly and at high speed. Since the speed correction coefficient for converting the back electromotive force into the speed is calibrated, it can be calibrated to an appropriate speed correction coefficient according to the apparatus and temperature, and an accurate speed can be obtained even if the back electromotive voltage is detected.

It is a top view of the memory | storage device of one embodiment of this invention. It is sectional drawing of the memory | storage device of FIG. It is sectional drawing of the lamp member of FIG. It is a front view of the lamp member of FIG. FIG. 2 is a block diagram of the storage device in FIG. 1. FIG. 6 is a block diagram of the counter electromotive voltage detection circuit of FIG. 5. It is an unload processing flow figure of one embodiment of the invention. It is a load processing flow figure of one embodiment of the invention. It is explanatory drawing of the coil both-ends voltage for the speed detection of this invention. It is explanatory drawing of the VCM current update timing of a comparative example. It is a speed detection process flow figure of one embodiment of the present invention. It is explanatory drawing of the transient response model of the process of FIG. It is explanatory drawing of the speed detection sample interval of one embodiment of this invention. It is explanatory drawing of the VCM current update timing of one embodiment of this invention. It is another load processing flowchart of this invention. It is operation | movement explanatory drawing of the other load process of this invention. It is another unload processing flowchart of the present invention. It is operation | movement explanatory drawing of the other unload process of this invention.

Explanation of symbols

3 Actuator 4 Magnetic head 5 Spindle motor 6 Magnetic disk 11 Lamp member 13 VCM drive circuit 13-1 Back electromotive voltage detection circuit 19 MPU

Claims (5)

A head for reading at least a storage medium;
An actuator for positioning the head at a predetermined position of the storage medium;
A ramp member provided at a position outside the storage medium and supporting the head;
A counter electromotive voltage detection circuit for detecting a counter electromotive voltage of the actuator;
Storage means for storing a correction coefficient for converting the back electromotive voltage into the moving speed;
The head is unloaded from the storage medium to the position of the ramp member, and the head is loaded from the ramp member to the storage medium, and at the time of unloading or loading, the output of the back electromotive voltage detection circuit And, using a correction coefficient of the storage means, detecting a moving speed of the actuator, and a control means for controlling the speed of the actuator,
The control means calibrates the correction coefficient from a moving speed of the actuator calculated from position information of the storage medium read by the head and a moving speed of the actuator calculated from the back electromotive voltage. A storage device. The storage device of claim 1.
The control means moves the head over the storage medium at the start of the unloading, calculates the moving speed of the actuator from the position information of the storage medium read by the head, and uses the back electromotive voltage. A storage device that calculates a moving speed of the actuator and calibrates the correction coefficient from the calculated moving speeds. The storage device of claim 2.
The storage device, wherein the control means performs speed control at the time of unloading using the calibrated correction coefficient. The storage device of claim 1.
The control means moves the head from the first position to the second position of the storage medium and calculates the moving speed of the actuator from the position information of the storage medium read by the head for each sample. And calculating the moving speed of the actuator from the back electromotive force, calculating the correction coefficient from the calculated moving speed, and calculating the correction coefficient by an average value of the calculated correction coefficients of a plurality of samples. A storage device characterized by calibrating. The storage device of claim 1.
The control means calibrates the correction coefficient based on a ratio between a moving speed of the actuator calculated from position information of the storage medium read by the head and a moving speed of the actuator calculated from the back electromotive voltage. A storage device.

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