JP4237163B2 - Actuator speed control device and storage device - Google Patents

Description

  The present invention relates to an actuator speed control device and a storage device for detecting the speed of an actuator from a back electromotive force of the actuator, and more particularly to a head for reading a storage medium when an access command does not arrive for a predetermined time. The present invention relates to an actuator speed control device and a storage device for performing an unload operation for evacuation outside the storage medium.

  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) Although it is well known to detect the speed from the back electromotive voltage of the motor (actuator), a transient response occurs due to the inductance of the motor. For this reason, it is necessary to wait for detection of the counter electromotive voltage for speed detection until the transient response is settled. For this reason, there was a problem that the detection interval could not be shortened and it was difficult to control the speed with high accuracy.

  An object of the present invention is to provide an actuator speed control device and a storage device for performing high-precision speed control by shortening the detection interval of the back electromotive force voltage of the actuator.

In order to achieve this object, the present invention provides an actuator speed control device that detects the speed of the actuator from the back electromotive voltage of the actuator and controls the speed of the actuator, and detects the back electromotive voltage of the actuator. wherein the electromotive voltage detection circuit detects a moving speed of the actuator from the output of the counter electromotive voltage detection circuit, to update the drive current of the actuator, and a control unit for speed control, the command current value in advance unit step And a memory for storing a transient response model obtained by measuring a voltage value at both ends of the actuator, and the control unit drives the actuator according to the detected moving speed for each sample. updates the current, after updating the drive current, the detected voltage value of the counter electromotive voltage detection circuit And sample, reading, from said transient response model of memory, the search of the transient response voltage value of the sample point of time of the detection voltage of the counter electromotive voltage detection circuit, from the detected voltage value, determined transient response voltage value of the actuator Is subtracted to calculate the back electromotive voltage of the actuator, and the moving speed of the actuator is calculated from the back electromotive voltage.

Further, the storage device of the present invention includes a head for reading at least a storage medium, an actuator for positioning the head at a predetermined position of the storage medium, a lamp member provided at a position outside the storage medium and supporting the head, A back electromotive force detection circuit for detecting a back electromotive voltage of the actuator, and a transient response model of the actuator obtained by supplying an instruction current value of a unit step to the actuator in advance and measuring a voltage value across the actuator. Storage means for storing, and a control unit for driving and controlling the actuator, wherein the control unit unloads the head from the storage medium to the position of the ramp member, and the head is moved to the ramp. with loading into the storage medium from the member, during the unloading or loading, for each sample, the detected shift The actuator drive current is updated according to the speed, and after updating the drive current, the detected voltage value of the back electromotive voltage detection circuit is sampled and read, and the inverse obtained from the transient response model of the storage means The transient response voltage value at the sample time of the detection voltage of the detection voltage detection circuit is obtained, the transient response voltage value of the actuator is subtracted from the detection voltage value, the back electromotive voltage of the actuator is calculated, and the back electromotive voltage is calculated. The moving speed of the actuator is calculated and the speed of the actuator is controlled.

  In the present invention, the transient response voltage value of the actuator is calculated, the output of the back electromotive voltage detection circuit is corrected, the moving speed is calculated, and this is used for calculating the control amount of the speed control. Speed control is possible.

  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 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).

  (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 undergoes a transient response immediately after the current update of the VCM, and the transient response settles after a certain time. 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.

  Thereby, 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 slides 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-described embodiment, the unload control of the head of the magnetic disk drive has been described. However, it can be applied to other storage devices such as the unload control of the head 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 transient response voltage value of the actuator is calculated and subtracted from the detected voltage, an accurate speed can be obtained even if the counter electromotive voltage is detected during the transient response of the actuator. As a result, the current update interval is shortened, and highly accurate speed control is possible.

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)

In the actuator speed control device for detecting the speed of the actuator from the back electromotive voltage of the actuator and controlling the speed of the actuator,
A counter electromotive voltage detection circuit for detecting a counter electromotive voltage of the actuator;
A controller that detects the moving speed of the actuator from the output of the back electromotive voltage detection circuit, updates the driving current of the actuator , and controls the speed ;
A memory for storing a transient response model obtained by supplying an instruction current value of a unit step to the actuator in advance and measuring a voltage value at both ends of the actuator ;
The control unit updates the driving current of the actuator according to the detected moving speed for each sample, and after updating the driving current , samples and reads the detection voltage value of the back electromotive voltage detection circuit. , from the transient response model of said memory, said search of the transient response voltage value of the sample point of time of the detection voltage of the counter electromotive voltage detection circuit, from the detected voltage value, subtracts the transient response voltage values obtained of said actuator, said actuator The actuator speed control device is characterized in that a back electromotive voltage is calculated and a moving speed of the actuator is calculated from the back electromotive voltage. The back electromotive voltage detection circuit includes:
A sense resistor of the actuator coil having resistance and inductance;
A first resistor provided in parallel with the sense resistor for detecting a back electromotive voltage corresponding to the sense resistor;
A second resistor connected in series with the first resistor for detecting a back electromotive voltage corresponding to the resistance of the actuator;
An amplifier that subtracts the potential at the midpoint of the first and second resistors from the potential of the sense resistor;
The actuator speed control device according to claim 1 , further comprising a differential amplifier that takes a difference between a resistance potential of the actuator and an output potential of the amplifier . 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 transient response model of the actuator obtained by supplying an instruction current value of a unit step to the actuator in advance and measuring a voltage value across the actuator ;
A control unit for driving and controlling the actuator,
The controller is
Unloading the head from the storage medium to the position of the ramp member, and loading the head from the ramp member to the storage medium;
At the time of unloading or loading, for each sample, the actuator driving current is updated according to the detected moving speed, and after updating the driving current, the detection voltage value of the back electromotive voltage detection circuit is sampled, Read, obtain the transient response voltage value at the sample time of the detection voltage of the back electromotive voltage detection circuit obtained from the transient response model of the storage means , subtract the transient response voltage value of the actuator from the detection voltage value, A storage device that calculates a back electromotive force of an actuator, calculates a moving speed of the actuator from the back electromotive voltage, and controls the speed of the actuator. The back electromotive voltage detection circuit includes:
A sense resistor of the actuator coil having resistance and inductance;
A first resistor provided in parallel with the sense resistor for detecting a back electromotive voltage corresponding to the sense resistor;
A second resistor connected in series with the first resistor for detecting a back electromotive voltage corresponding to the resistance of the actuator;
An amplifier that subtracts the potential at the midpoint of the first and second resistors from the potential of the sense resistor;
The storage device according to claim 3 , further comprising a differential amplifier that takes a difference between a resistance potential of the actuator and an output potential of the amplifier . The storage means includes
A transient response value at each time obtained by supplying an instruction current value of the unit step to the actuator in advance and measuring a voltage value across the actuator at the measurement time interval is stored as the transient response model. The storage device according to claim 3.

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