JP3819179B2 - Magnetic disk drive and its impact detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic disk device and its impact detection method.
[0002]
[Prior art]
In recent years, high-density recording, large capacity, and miniaturization of the disk surface of magnetic disk devices have progressed, and it is expected that recording and reproduction of information will be impossible even if the disk surface is slightly scratched. There is an urgent need to develop technology to protect the disk surface.
[0003]
A contact start / stop (CSS) method has been widely adopted as a carriage drive method of a conventional magnetic disk device.
[0004]
This CSS method is used when the magnetic disk medium is stopped (during standby, when the power is turned off, etc.) on the surface of the magnetic disk medium where no information is recorded, for example, on the surface of the landing shopping zone provided on the inner periphery of the disk. In this method, the magnetic head is retracted while being in contact, and the magnetic head is floated as the rotation of the magnetic disk medium increases during read / write, and a seek operation is performed from this zone.
[0005]
In the case of this CSS system, although there is an advantage that the operation at the time of reading / writing is speedy, even in the area where information is not recorded, the magnetic head is always placed on the surface of the magnetic disk medium. Is not strong.
[0006]
In the case of this CSS system, it is based on the premise that there is an area where information is not recorded on the disk surface. In the future, information may be recorded with a larger capacity and higher density in this area. Conceivable.
[0007]
Therefore, in recent years, a technique called a head load / unload system has been devised.
[0008]
This head load / unload method is used to save a magnetic head on an island-shaped head retraction part (hereinafter referred to as a ramp) provided independently on the outside of the magnetic disk when the magnetic disk device is not in operation or in a standby mode. In this method, the magnetic head is loaded from the ramp to the disk surface side during read / write, and the magnetic head is unloaded from the disk surface to the ramp side at the end of read / write.
[0009]
By the way, when this head load / unload method is adopted, the magnetic head must always be floated with respect to the disk surface, and the distance between them must be kept as small as possible. While moving (loading), it is necessary to detect the impact more precisely. On the other hand, since the magnetic head is strong against the impact while waiting on the lamp, the sensitivity to the impact is dull, in other words, it is necessary to increase the detection level.
[0010]
[Problems to be solved by the invention]
However, in the conventional CSS system, since only one impact sensor is provided in relation to the disk surface and the magnetic head, only one detection output can be obtained, and there is no idea of changing the detection level for impact. For this purpose, a plurality of sensors having different detection levels are used, and there is a problem that the cost cannot be avoided.
[0011]
Also, in order to detect all levels of impact with a single impact sensor, if an intermediate value is set, unnecessary impact detection occurs, and retry operations occur frequently during load operations, making the load operations smooth. There is also a problem that it cannot be done.
[0012]
The present invention has been made to solve such a problem. The disk apparatus is adapted to a plurality of operating states of the magnetic head and uses a smaller number of sensors than the number of the operating states to remove the disk device from an impact. It is an object of the present invention to provide a magnetic disk device that can be protected and an impact detection method thereof.
[0013]
It is another object of the present invention to provide a magnetic disk device and an impact detection method thereof that can reduce a retry operation from unnecessary impact detection and perform a load operation smoothly.
[0017]
In order to achieve the above object, the present inventionThe magnetic disk device receives a read or write command from a host, and instructs a real operation of load / unload / seek / on-track in response to the received command, and rotates and drives the magnetic disk. Driving means for moving a magnetic head for writing and reading information on the disk, and impact detecting means for detecting an impact applied to the magnetic disk and the driving means including the magnetic head and outputting a detection signal corresponding to the amount When the impact is detected, the drive means is operated to protect the magnetic disk and the magnetic head, and load / unload / seek / on-track operation instructions from the hard disk controller. The gain of the detection signal is switched according to A CPU that outputs a control signal, a gain setting value that is switched by the control signal, a gain switch that variably outputs a detection signal input from the impact detection means based on the gain setting value, and the gain And a means for notifying the CPU of the impact detection when the detection signal output from the switch exceeds a predetermined threshold value.
[0020]
In the present invention,When the CPU outputs a control signal for switching the gain of the detection signal in response to load / unload / seek / on-track operation instructions from the hard disk controller, the gain setting value of the gain switch is switched by the control signal.
  The gain switch variably outputs the detection signal input from the impact detection means based on the gain setting value switched according to the operation instruction. When this detection signal exceeds a predetermined threshold, the CPU is notified that an impact has been detected.Using fewer sensors than the number of operating states of the magnetic headMagneticThe disk can be protected.
[0021]
Also, by invalidating the impact detection by the detection means for a predetermined period during which the magnetic head is operated or stopped, the retry operation from unnecessary impact detection can be reduced, and the load operation can be performed smoothly.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention will be described with reference to the drawings.
[0023]
FIG. 1 is a perspective view showing a configuration of a magnetic disk apparatus according to an embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a functional block diagram thereof. The magnetic disk apparatus of this embodiment employs a head load / unload system.
[0024]
As shown in these drawings, the head load / unload type magnetic disk apparatus includes a magnetic disk 1 as a recording medium, a spindle motor 2 (hereinafter referred to as SPM 2) for rotating the magnetic disk 1, and A head actuator 3 in which a plurality of arms 8 mounted with a magnetic head 18 are fixed in multiple stages, a voice coil motor 4 (hereinafter referred to as VCM 4) for driving the head actuator 3, and a magnetic disk device when not operating and in a standby mode , A ramp 5 serving as an island-shaped head evacuation section for positioning (standby) the magnetic head 18 at a fixed position outside the magnetic disk 1 is provided.
[0025]
The ramp 5 includes a step portion 5a for guiding the tab 6 protruding from the tip portion of the arm 8, and a restraint portion 5b for restraining the tab 6 guided and moved by the step portion 5a to a fixed position. The magnetic head portion is protected from jumping out to the disk surface due to an impact on the disk drive even when the disk is being rotated or stopped.
[0026]
As shown in FIG. 3, the magnetic disk device includes a CPU 11 that controls the entire device, and a hard disk controller that controls input / output of various commands and read / write data between the host and the inside of the device. HDC) 12, voice coil motor driver IC (VCM driver IC) 13 for driving and controlling VCM 4, spindle motor driver IC (SPM driver IC) 14 for driving and controlling SPM 2, and read / write for processing read / write data An impact sensor for detecting an impact on the circuit 16 and the buffer memory 17, which is a primary storage area of the read / write data, the magnetic head 18, and the magnetic disk device main body, and converting the detected amount into an analog waveform (analog signal) and outputting it 21. Amplifies the analog signal output from the impact sensor 21 Amplifier 22, a low-pass filter 23 (hereinafter referred to as LPF 23) that cuts a high-frequency component of the analog signal amplified by the amplifier 22, and the gain (gain) of the detection signal input from the LPF 23 is set to a set level set by the CPU 11. A variable gain output device 24 that outputs a variable signal, and determines whether or not the detection signal input from the gain control device 24 is within a certain range, and outputs an impact detection signal, for example, a pulse signal, when it falls outside the certain range. And a latch circuit 26 for latching an impact detection signal (pulse signal) output from the comparator 25 and outputting it to the CPU 11 to notify the occurrence of the impact.
[0027]
The CPU 11 has a flash memory (FROM) 15 in which firmware is stored, and executes overall control and various data processing operations in accordance with the firmware stored in the FROM 15.
[0028]
For example, when the HDC 12 receives a read / write command transferred from the host, the CPU 11 is caused to execute a specific operation for the received read / write command, that is, a load operation, a seek operation, an on-track operation, or an unload operation. Since the instruction is given, the CPU 11 controls the VCM driver IC 13 and the SPM driver IC 14 so that the VCM 3 and the SPM 2 operate in response to each command from the HDC 12.
[0029]
Further, the CPU 11 outputs a control signal to the gain switch according to the operation state of the drive to switch the gain (sensitivity).
[0030]
Further, the CPU 11 enters a standby mode for power saving when the read / write command is not sent for a certain period of time. The standby mode is a mode in which the magnetic head portion is made to stand by at a standby position provided by the ramp 5 and the spindle motor 2 is driven at a predetermined rotational speed lower than the rated rotational speed. Here, the rated rotational speed is a disk rotational speed for reading / writing data from / to the magnetic disk 1. The disk rotation speed in the standby mode is the time required for the magnetic head waiting on the ramp 5 to start moving toward the inside of the magnetic disk 1 until it reaches the data recording area on the magnetic disk 1, that is, It is determined in consideration of the load time. That is, the disk rotational speed in the standby mode is determined so that the time required for the SPM 2 to reach the rated rotational speed from the constant rotational speed during standby is substantially equal to the load time.
[0031]
Next, the basic operation of this magnetic disk device will be described.
In the standby mode, the SPM 2 is driven at a predetermined rotational speed that is determined in consideration of the load time and is lower than the rated rotational speed. When a read / write command from the host is generated, the hard disk controller (HDC) 12 receives it and sends it to the CPU 11 as each operation command (instruction command such as load / unload / seek / on-track). When the CPU 11 receives a command for each operation, the CPU 11 immediately cancels the standby mode and executes a procedure for executing each operation.
[0032]
First, the CPU 11 sends control signals b, c, d to the SPM driver IC 14, the VCM driver IC 13, and the gain switch 24 at the same timing.
[0033]
That is, the CPU 11 sends to the SPM driver IC 14 a control signal b instructing to supply the SPM 2 with a drive current necessary for driving the magnetic disk 1 at the rated rotational speed, and at the same time to the VCM driver IC 13. Sends a control signal c for instructing the VCM 4 to supply a drive current for moving the magnetic head 18 toward the inside of the magnetic disk 1, and further detects to the gain switch 24 according to each operation command. A control signal d for level setting is sent.
[0034]
The operation from the impact detection of the magnetic disk device will be described below.
If the magnetic head 18 is completely unloaded when an impact is applied to the magnetic disk device, the magnetic head 18 is localized in the back of the step portion of the ramp 5, and even if the impact is quite high. There is no worry that the data recorded on the disk will be destroyed.
[0035]
However, while the ramp is being loaded, the magnetic head 18 is levitated with respect to the disk surface, but when an impact of a certain level or more is applied, the magnetic head 18 falls from the ramp 5 onto the magnetic disk 1, Data recorded on the magnetic disk 1 and the magnetic head 18 are destroyed.
[0036]
If the track is on track and the write operation is being performed, the data is erroneously written to another area on the disk surface due to the shake of the magnetic head 18 and is already recorded in that area. The original data that should have been erased.
[0037]
Therefore, the shock detection level can be changed in advance, and if it is during ramp loading, even if it is a little impact, the loading is stopped in advance and changed to an unload operation, or if it is on track, writing is prohibited. Can be processed.
[0038]
By the way, the level of impact to be detected is not the same between ramp loading and on-tracking.
[0039]
In other words, when the ramp is loaded, the magnetic head 18 moves while rubbing the stepped portion of the ramp 5, so that the resistance is large, and the current for surpassing this resistance changes greatly and the carriage starts to move. There is no need to do.
[0040]
On the other hand, during on-track, there is no large change in current or movement of the carriage, and there is a possibility of writing, so it is desirable to detect an impact exceeding 2G, for example.
[0041]
In this way, when two impacts with detection levels as far apart as 10G and 2G are to be detected, two impact sensors for detecting each level are generally required. If this is to be covered by a single impact sensor, it is conceivable to set the detection level to an intermediate value, for example, about 5G. However, in this case, on-track impact detection that requires particularly sensitive detection is possible. May not be performed correctly.
[0042]
Therefore, in this embodiment, the detection level can be varied by switching the gain of the detection signal obtained from one impact sensor 21 in a plurality of stages according to the operation state, and the impact level can be detected in different operation states. I have to.
[0043]
That is, in the case of this magnetic disk device, when an impact is applied to the disk drive body, the impact sensor 21 detects the impact and outputs this as an analog signal. Since this output signal is very small, it is amplified by the amplifier 22, the high frequency is cut by the LPF 23, and input to the comparator 25 through the gain switch 24 as a detection signal.
[0044]
On the other hand, the CPU 11 operates at that time, for example, when the magnetic head 18 is retracted to the ramp 5 (hereinafter referred to as unloading), or when the magnetic head 18 floats from the ramp 5 onto the disk surface (hereinafter referred to as ramp loading). When the magnetic head 18 moved to the disk surface is moved to the target cylinder (hereinafter referred to as seek time), when the target cylinder is captured and the magnetic head follows (hereinafter referred to as on-track time). ), The respective control signals are sent to the gain switch 24, and the detection level of the gain switch 24 is switched to any one of 2G, 5G, and 10G, so that it is input from the LPF 23 to the gain switch 24. The detection signal is changed to a gain (sensitivity) in each operation state and is output to the comparator 25.
[0045]
The gain ratio at this time is set to, for example, twice or more.
For example, when unloading while the magnetic head 18 is retracted to the ramp 5, the gain is set low, the reach to the threshold is wide, for example, up to about 10G, the shock detection sensitivity is insensitive, and the movement of the magnetic head 18 is large. When ramp loading or seeking, the gain is set to an intermediate setting, the reach to the threshold is set to the middle, for example, up to about 5G, the impact detection sensitivity is set to a medium level, and the gain at the time of on-track where the movement of the magnetic head 18 is small. Is set high, the reach to the threshold is the narrowest, for example, about 2G, and the impact detection sensitivity is made most sensitive.
[0046]
When the gain-converted detection signal from the gain switch 24 is input to the comparator 25, the comparator 25 compares the level of the input detection signal with a preset constant voltage (threshold voltage). When the detection signal exceeds the threshold value or exceeds a certain range, an impact detection signal, for example, a pulse such as HI is output to the latch circuit 26, and the latch circuit 26 latches the impact detection signal. An input is made to the CPU 11 to notify that an impact exceeding the level has been applied.
[0047]
Thereby, the CPU 11 can control the VCM 4 and the SPM 2 and perform data processing according to the operation state.
[0048]
For example, control can be performed such as changing to unload operation during ramp loading, or prohibiting write operation during write operation during on-track.
[0049]
FIG. 4 shows a flowchart of an operation for setting the impact gain according to the operation state. Upon receiving a command from the HDC 12, a load operation or a seek operation is performed according to the type of the command.
[0050]
Here, when the CPU 11 controls the VCM 3 or SPM 2, it sends a control signal d to the gain switch 24 to set a gain for impact detection.
[0051]
In this case, as shown in FIG. 4, the CPU 11 first determines whether or not the received command is a load instruction (S101). If the command is a load instruction (Yes in S101), the detection level is set to 10G. The control signal d is sent to the gain switch 24 so that the gain of the detection signal is changed (S102).
[0052]
If the command is not a load instruction (No in S101), the CPU 11 determines whether the received command is a seek instruction (S103). If the command is a seek (Yes in S103), the detection level is set to 5G. Thus, the control signal d is sent to the gain switch 24 so that the gain switch 24 is set to change the gain of the detection signal (S104).
[0053]
If the command is not a seek command (No in S103), the remaining command is an on-track command. At this time, the CPU 11 sends a control signal d to the gain switch 24 so that the detection level becomes 2G. Then, a setting for changing the gain of the detection signal is performed on the gain switch 24 (S105).
[0054]
Next, the operation of the entire magnetic disk device will be described.
When the impact sensor 21 detects an impact on the magnetic disk device main body, the CPU 11 first determines whether or not the loading is in progress (S201).
[0055]
As a result of the determination, if the load is being loaded and the impact detection is not masked (NO in S202), the CPU 11 determines whether or not the impact magnitude is 10G (already set in the process of S102 in FIG. 42) or more. Judgment is made (S203).
[0056]
If the determination result is 10G or more, the CPU 11 stops the loading operation (S204) and executes the unloading operation (S205).
[0057]
On the other hand, if the result of the determination is that the load is not in progress (NO in S201), the CPU 11 determines whether or not the seek is in progress (S206), the seek is in progress (YES in S206), and the impact detection is masked. If not (NO in S207), it is determined whether or not the magnitude of impact is 5G (already set in the process of S104 in FIG. 4) or more (S208), and if 5G or more (YES in S208), seek is performed. The operation is stopped (S209), and the unload operation is executed (S205).
[0058]
On the other hand, when the seek is not in progress (NO in S206), the on-track operation is in progress. Therefore, if the impact detection is not masked during the on-track operation (NO in S210), the CPU 11 determines that the impact magnitude is 2G (NO in S210). 4 is determined (S211). If 2G or more (YES in S211), the write operation is prohibited (S212) and the unload operation is executed (S211). S205). In this way, by using one impact sensor 21, different impact levels (10G, 5G in this example) are selected according to respective operation states such as unload operation, load operation, seek operation, and on-track operation. , 2G) can be detected.
[0059]
If an impact is detected at each set level, an unload operation is performed, and then the process is repeated again from the load operation.
[0060]
Each in-mask determination process of S202, S207, and S210 is used when the CPU 11 sets a period during which the impact sensor 21 detects it even if it is detected.
[0061]
Hereinafter, the case of masking impact detection will be described in detail.
When a current is passed at the beginning of loading and the lamp 5 is moved, or when a current is passed in a calibration operation performed before loading, it is often detected as an impact even though the operation is normal.
[0062]
The calibration operation is to measure the back electromotive voltage when the magnetic head 18 is at speed 0 (when stopped) in order to correct the variation of the back electromotive force detection circuit of the VCM 4 before loading.
[0063]
Since the magnetic head 18 is pressed against the end of the ramp 5 by passing an electric current in the direction in which the magnetic head 18 is moved in the outer circumferential direction, the carriage does not move, and the counter electromotive voltage at zero speed can be measured. Normally, this measurement is performed three times by changing the flowing current.
[0064]
In this way, the load operation cannot be executed if the load is unloaded each time the predicted impact detection is not caused by an actual impact.
[0065]
Therefore, even if the impact detection signal from the latch circuit 26 is input to the CPU 11 for a certain period until the measurement is finished, the impact notification is masked on the CPU 11 side, and the mask is released after the certain period has elapsed. Only the impact that is originally required is reliably detected.
[0066]
Hereinafter, specific events that may occur during operation of the magnetic disk device will be described with reference to FIGS.
[0067]
6-8, (a) is the impact detection signal output from the comparator 25, (b) is the impact detection signal after latch output from the latch circuit, (c) is the VCM current, (a) (C) All horizontal axes represent time. The vertical axis of (c) indicates the current, the intersection with the horizontal axis (dotted line) indicates the current 0, the direction of the current flowing so that the positive direction (upward in the figure) moves the magnetic head toward the disk outer circumference, and the negative The direction (the downward direction in the figure) indicates the direction of the current that flows so that the magnetic head moves in the inner circumferential direction of the disk. The VCM current is not shown in the block diagram of FIG. 1, but is a current that flows in the VCM 4 that drives the carriage of a general magnetic disk device. The carriage refers to a movable part including the head actuator 3, the arm 8, and the magnetic head 18.
[0068]
6 shows a case where the loading operation of the magnetic head 18 is normally performed without detecting an impact, and FIG. 7 shows a case where an impact is detected while the magnetic head 18 is moving on the step portion 5a of the ramp 5. FIG. 8 is a diagram showing each operation as a change in the VCM current during calibration, that is, when an impact is detected before the magnetic head 18 retracted from the lamp 5 and stopped is moved.
[0069]
First, a normal loading operation will be described with reference to FIG.
Before moving the magnetic head 18 retracted from the ramp 5 from the ramp 5, as shown in FIG. 5C, first, the VCM current is passed through the first period 61, about 300 mA (medium), In the next second period 62, a calibration operation is performed in which the VCM current is raised to 400 mA, and in the final third period 63, the VCM current is lowered to about 210 mA. That is, the operation of pressing the magnetic head 18 to the outer peripheral side, that is, the end of the ramp 5 is performed by changing the current amount in three stages.
[0070]
After performing the three-stage calibration operation, the VCM current is applied in the direction opposite to that in the past, that is, the direction in which the magnetic head 18 moves toward the inner peripheral side of the magnetic disk (hereinafter referred to as the inner peripheral side). During the fourth period 64, the magnetic head 18 is pushed to the inner peripheral side. In a subsequent fifth period 65, as a loading operation, the carriage (magnetic head) is moved toward the inner peripheral side while rubbing the tab 6 on the stage of the lip 5 while controlling the speed of the carriage.
[0071]
FIG. 7 is a diagram showing an operation when an impact is detected while the tab 6 is moving on the lamp 5, for example, during execution of the load operation shown in FIG.
[0072]
In this case, similarly to the operation of FIG. 6, after performing the calibration operation from the first period 61 to the third period 63, the VCM current is applied only in the fourth period 64 in the opposite direction. In this fourth period 64, for example, at the timing 71 in FIG. 7, for example, the impact detection signal (pulse) 72 in FIG. 7A is output from the comparator 25, and this is shown in the latch circuit 26. When latched as HI73 as shown in 7 (b), the CPU 11 determines an impact, and after that, as the unload operation, after stopping the flow of the VCM current in the sixth period 74, the load operation is stopped. In the seventh period 75, the VCM current is passed in the positive direction, and in the subsequent period 76, the carriage (magnetic head) is directed toward the outer peripheral side while rubbing the tab 6 on the step portion 5a of the lip 5 while controlling the carriage speed. It moves me. Although not shown, after the unload operation, the calibration operation is retried again.
[0073]
FIG. 8 is a diagram showing an operation when an impact is detected during the calibration period, for example, during the execution of the loading operation shown in FIG.
[0074]
In this case, the operation is the same as that in FIG. 6 until the first period 61 shifts to the second period 62.
[0075]
Then, within the second period 62, for example, at the timing 81 in FIG. 8C, the impact detection signal (pulse) 82 in FIG. 8A is output from the comparator 25, and this is output by the latch circuit 26 in FIG. When latched in the HI 83 as shown in b), the CPU 11 determines that the shock has occurred and stops the calibration operation. Thereafter, the flow of the VCM current is stopped during the period 84 in FIG. 8C, and again in FIG. In the same manner as shown, the calibration operation is retried in the order of the first period 61 and the second period 62.
[0076]
As described above, when the CPU 11 detects an impact at the timings of FIGS. 7 and 8, the retry is repeated, and the load operation is often impossible. Therefore, for example, if masking is made so as not to detect the impact in the second period 62 and the fourth period 64 in FIG. 6 and it is disabled, unnecessary impact detection is not required and the load operation can be performed smoothly. become.
[0077]
As described above, according to the magnetic disk apparatus of this embodiment, when the head loading / unloading method is adopted, the CPU 11 controls the gain switch 24 according to the operation state of the carriage including the magnetic head 18 to detect the impact sensor. 21. Since the gain of the detection signal obtained from 21 is changed and then input to the comparator 25, for example, when the gain of the detection signal is set low with respect to the gain switch 24, the comparator 25 has a constant threshold value. If the detection signal gain is increased and the gain of the detection signal is set high, the range up to the threshold value is narrowed and the impact detection sensitivity is increased. Impact can be detected at the detection level.
[0078]
That is, only one impact sensor 18 can cope with different operating states of the carriage portion including the magnetic head 18 between the magnetic disk 1 and the ramp 5 in the head load / unload system, and the magnetic disk 1 and the magnetic head 18 are protected from the impact. Can be protected.
[0079]
Further, the CPU 11 invalidates the impact detection signal notified through the comparator 25 and the latch circuit 26 during a predetermined period in which the magnetic head 18 is operated or stopped, for example, in the second period 62 and the fourth period 64 shown in FIG. By doing so, it is possible to reduce the retry operation for unnecessary detection.
[0080]
In addition, this invention is not limited only to the said embodiment.
[0081]
In the above embodiment, one impact sensor 18 is used, and impacts are made at three levels of 2G, 5G, and 10G among the four operation states of the magnetic disk device such as unload, ramp load, seek, and on-track. However, if the impact level difference is larger than this, two impact sensors may be used and a plurality of operation states may be assigned to each.
[0082]
That is, the present invention is effective when the number of operating states or detection levels is greater than the number of sensors.
[0083]
【The invention's effect】
As described above, according to the present invention, when adopting the head load / unload method, the gain of the detection signal obtained from the impact detection means is varied corresponding to each of the plurality of operating states of the magnetic head, Therefore, it is possible to protect the disk device from the impact by using a smaller number of sensors corresponding to a plurality of operating states of the magnetic head.
[0084]
Also, by invalidating the impact detection by the detection means for a predetermined period during which the magnetic head is operated or stopped, the retry operation from unnecessary impact detection can be reduced, and the load operation can be performed smoothly.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a magnetic disk device according to an embodiment of the present invention.
FIG. 2 is a plan view of the magnetic disk device of FIG.
3 is a functional block diagram of the magnetic disk device of FIG.
FIG. 4 is a flowchart when the CPU sets an impact gain according to an operation state.
FIG. 5 is a flowchart showing an impact detection operation of the magnetic disk device.
FIG. 6 is a diagram showing a change in the VCM current when the magnetic head load operation is normally performed without detecting an impact.
FIG. 7 is a diagram showing a change in the VCM current when the CPU detects an impact when the magnetic head is moving along the ramp step.
FIG. 8 is a diagram illustrating a CPU operation when an impact is detected during a calibration operation, by a change in VCM current.
[Explanation of symbols]
1 ... Magnetic disk
2 ... Spindle motor (SPM)
3. Head actuator
4. Voice coil motor (VCM)
5 ... Lamp
6 ... Tab
11 ... CPU
12 ... Hard disk controller (HDC)
13. Voice coil motor driver IC (VCM driver IC)
14 ... Spindle motor driver IC (SPM driver IC)
18 ... Magnetic head
21 ... Sensor
22 ... Amplifier
23 ... Low-pass filter (LPF)
24 ... Gain switch
25 ... Comparator
26 ... Latch circuit

Claims (1)

A hard disk controller that accepts a read or write command from the host and instructs the received command to perform actual load / unload / seek / on-track operations;
Drive means for rotating a magnetic disk and moving a magnetic head for writing and reading information on the magnetic disk;
An impact detection means for detecting an impact applied to the drive means including the magnetic disk and the magnetic head and outputting a detection signal corresponding to the amount;
When it is notified that an impact has been detected, the drive means is operated to protect the magnetic disk and the magnetic head, and in response to load / unload / seek / on-track operation instructions from the hard disk controller. A CPU that outputs a control signal for switching the gain of the detection signal;
A gain switching value that is switched by the control signal, and that variably outputs a detection signal input from the impact detection means based on the gain setting value; and
And a means for notifying the CPU of shock detection when the detection signal output from the gain switch exceeds a predetermined threshold value.

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