JP2003151257A - Static electricity sensor mounted disk storage device and static electricity application detecting method of the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of a disk storage device by predicting head destruction caused by static electricity in order to avoid the loss of important data. SOLUTION: A static electricity sensor 40 which is constituted of a thin film resistor body that is weaker than heads 35-0 to 35-3 for electrostatic destruction and broken by the application of static electricity exceeding a reference level and is put into a non-conductive state, is arranged in the vicinity of the heads 35-0 to 35-3. A CPU 57 monitors the electrically conductive state of the sensor 40 through a sensor amplifier circuit 56 and a gate array 54 and detects the fact that static electricity exceeding the reference level is applied to the heads 35-0 to 35-3 in accordance with the monitoring result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk storage device in which at least information is read by a head, and more particularly to a disk storage device equipped with an electrostatic sensor for detecting the application of static electricity and a static electricity application detection method in the same. .

[0002]

2. Description of the Related Art Recently, in a disk storage device in which information is read / written by a head, for example, a magnetic disk device, a magnetoresistive effect called an MR head, which has a large reproduction output and is suitable for high recording density, in a read head It has become common to use a mold (Magneto Resistive) head.

However, since the MR head has a thin film structure, it has a problem that it is easily destroyed by the application of static electricity. In addition, MR heads are becoming finer year by year in order to cope with narrow track pitches and higher sensitivities aimed at higher recording densities, and are becoming more and more vulnerable to static electricity.

[0004]

The destruction of the head due to the application of static electricity in the magnetic disk device is fatal in the magnetic disk device because the data recorded on the magnetic disk cannot be read, that is, the data is lost. Target. However, avoiding head destruction due to the application of static electricity is also a difficult problem. In particular, when a part of the head is destroyed, the symptoms gradually progress to complete destruction, so that the destruction may not be detected in the inspection during manufacturing. Further, when used in an environment where static electricity is frequently applied, head destruction due to discharge or induction from the metal part of the housing may occur.

In such a case, in order to avoid the worst situation of head destruction in the end user, whether static electricity exceeding the head destruction level has been applied in the past,
Alternatively, it is an important issue to detect whether static electricity is frequently applied in the usage environment.

However, in the disk storage device equipped with the MR head, at present, no countermeasure is taken against such a problem.

The present invention has been made in view of the above circumstances, and an object thereof is to predict head damage due to static electricity, which is one of the most serious problems in recent disk storage devices, and is therefore important. It is an object of the present invention to provide a disk storage device capable of avoiding data loss and improving reliability, and a method of detecting static electricity application in the device.

[0008]

DISCLOSURE OF THE INVENTION A disk storage device according to a first aspect of the present invention is a disk storage device in which at least information is read by a head, which is weaker than the head with respect to electrostatic breakdown and has a reference level. An electrostatic sensor consisting of a thin-film resistor that becomes non-conductive when it is destroyed by the application of static electricity that exceeds it, that is, a destructive electrostatic sensor, and the conductive state of this electrostatic sensor is monitored, and the head is referenced according to the monitoring result. Means for detecting that static electricity exceeding a level is applied.

In the disk storage device having such a structure, the presence or absence of the damage of the electrostatic sensor composed of the thin film resistor, which is more susceptible to the electrostatic damage than the head, is monitored by the conductive state of the sensor, so that the head can be used as a reference. The application of static electricity exceeding the level can be easily detected without destroying the head. In addition, when the electrostatic sensor is destroyed by the application of static electricity exceeding the reference level in the non-operating state of the disk storage device, the destroyed state is maintained. It is possible to detect that static electricity exceeding the level is applied. That is, it is possible to detect the application of static electricity exceeding the reference level when the disk storage device is not operating.

A disk storage device according to a second aspect of the present invention monitors the potential of a capacitor type electrostatic sensor and the electrostatic sensor reflecting the amount of electric charge accumulated in the electrostatic sensor by application of static electricity, A means for detecting that static electricity exceeding a reference level is applied to the head according to the monitoring result is provided.

In the disk storage device having such a configuration, the electric potential of the capacitor type electrostatic sensor, that is, the nondestructive electrostatic sensor changes depending on the amount of electric charge accumulated in the sensor, and the electric charge amount changes. It changes depending on the amount of static electricity applied to the. Therefore, during operation of the disk storage device, by monitoring the potential of the static electricity sensor, it is possible to easily detect from the monitoring result that static electricity exceeding the reference level has been applied to the head. Further, since the capacitor type electrostatic sensor applied to the disk storage device according to the second aspect is a nondestructive type electrostatic sensor, unlike the destructive type electrostatic sensor, it is possible to detect static electricity applied to the head as many times as possible.

In the disk storage device according to the second aspect, a means for forcibly discharging the electric charge accumulated in the capacitor type electrostatic sensor, for example, a switch for short-circuiting the terminals of the electrostatic sensor is provided to store the electric charge. It is advisable to perform a detection operation that static electricity exceeding the reference level is applied to the head after the discharge is forcibly performed.

Further, in the disk storage device according to the second aspect, means for comparing the potential of the electrostatic sensor with a predetermined reference potential, for example, a comparator is provided, and the reference level is applied to the head according to the comparison result (output of the comparator). If the configuration is such that it is determined whether or not static electricity exceeding 10 is applied, the sensitivity of the sensor can be easily changed by changing the reference potential.

Further, in the disk storage device according to the second aspect, the comparison result of the comparison means (output of the comparator) is periodically checked, and the potential of the electrostatic sensor exceeds the reference potential within a fixed time. The number of detections is detected and the reference level is set on the head only when the number of detections exceeds a predetermined reference number, that is, when it is often detected that the electrostatic sensor potential exceeds the reference potential. If the configuration is such that it is determined that static electricity exceeding 10 is applied, it is possible to prevent erroneous determination due to the influence of noise or the like.

Further, in the disk storage device according to the first or second aspect, when it is detected that static electricity exceeding a reference level is applied to the head, the fact is notified to the host using the disk storage device. It is advisable to adopt the configuration. As described above, the notification (warning) to the host indicates that the head of the disk storage device has been damaged, and by prompting the backup of data, it is possible to prevent the loss of important data. It should be noted that the static electricity sensor may be arranged near the head, for example, on the tip end portion of the flexible printed circuit board that serves as a path to which static electricity is applied, or on the lowermost head suspension assembly of the stacked head suspension assemblies.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a magnetic disk device will be described below with reference to the drawings.
FIG. 1 is a perspective view showing the internal structure of a magnetic disk device according to an embodiment of the present invention.

The magnetic disk device shown in FIG. 1 (hereinafter referred to as HD
(Referred to as D) has a rectangular box-shaped conductive case 10 having an open top surface, and a top cover (not shown) that is screwed to the case 10 with a plurality of screws to close the upper end opening of the case 10. is doing.

At least one, for example, two disks (magnetic disk media) 11-0 and 11 are provided in the case 10.
-1 and a spindle motor (hereinafter referred to as SPM) 12 that supports and rotationally drives the disks 11-0 and 11-1.
And a head (magnetic head, which reads / writes information from / on each recording surface of the disks 11-0 and 11-1.
Composite heads) 35-0, 35-1 and 35-2, 35-3 (Fig. 2
And FIG. 3), the rotary actuator (carriage) 13 and the heads 35-0 to 35-3 move to the retreat position of the outermost circumference of the disks 11-0 and 11-1. A lamp (lamp mechanism) 14 held at a position separated from 11-0 and 11-1 and the substrate unit 1
5 and 5 are stored. Head 35-i (i = 1 to 3)
Is a composite head in which a read head including an MR (Magneto Resistive) element and a write head (inductive head) including an inductive recording thin film element are integrated on a slider. Here, the composite head 35-i will be referred to as an MR head 35-i for convenience.

Each of the disks 11-0 and 11-1 is a 2.5-inch type magnetic recording medium having a diameter of 65 mm, for example. At least one of the upper surface and the lower surface of the disks 11-0 and 11-1, for example, both surfaces form a recording surface for recording data. Disks 11-0 and 11-1 are SPM
Twelve hubs (not shown) are coaxially fitted to each other and are held by the clamp springs 16. Disk 11
-0 and 11-1 are rotationally driven by the SPM 12 at a predetermined speed.

The actuator 13 is a head suspension assembly (hereinafter referred to as HSA) arranged corresponding to each recording surface of the disks 11-0 and 11-1.
20-0, 20-1, 20-2, 20-3 and their HSA
Bearing assembly 22 in which 20-0, 20-1 and 20-2, 20-3 are rotatably supported with respect to the disks 11-0 and 11-1
And a voice coil motor (hereinafter, referred to as VCM) 24 that is a drive source of the actuator 13.

The ramp 14 is located on the outer peripheral side of the disks 11-0 and 11-1, and guides and supports the tab 29 (see FIGS. 2 and 3) of each HSA 20-i (i = 0 to 3). Has a face. Each guide surface is arranged according to the level of the corresponding suspension 28, and along the radial direction of the disks 11-0, 11-1.
11-1 extends to the vicinity of the outer peripheral edge of 11-1 and is arranged on the movement path of the tab 29.

On the outer surface of the bottom wall of the case 10, the SPM 12,
A main printed circuit board (not shown) (on which a circuit group is mounted) (not shown) for controlling operations of the VCM 24 and the heads 35-0 to 35-3 (see FIGS. 2 and 3) via the board unit 15 Referred to as) is screwed.

Each HSA 20-i has an arm 26 and a suspension 28, as shown in FIG. The base end of the suspension 28 is fixed to the tip of the arm 26 by spot welding or adhesion and extends from the arm 26. A tab 29 is provided on the tip of the suspension 28.
Are formed. The arm 26 is, for example, SUS30.
A stainless steel material such as No. 4 is formed into a thin flat plate having a plate thickness of about 0.3 mm, and the bearing assembly 22 is provided at the base end thereof.
A circular through hole 30 (see FIG. 3) for inserting the through hole is formed. The suspension 28 has a plate thickness of 50 to 75 μm.
It is composed of an elongated leaf spring. The suspension 28 may be formed integrally with the arm 26 by using the same material as that of the arm 26.

The HSA 20-i also has a suspension 28
And flexure fixed on arm 26
A flexible printed cable (flexible printed circuit board) for relay (hereinafter referred to as a relay FPC) 32-i, and an M mounted on the relay FPC 32-i.
The R head 35-i is provided.

The relay FPC 32-i is formed in an elongated strip shape and has a head wiring pattern 320-i connected to the MR head 35-i as shown in FIG. The head wiring pattern 320-i is formed on an insulating layer made of polyimide or the like formed on a stainless plate. Relay F
The PC 32-i is fixed on the surface of the suspension 28 and the arm 26 on the side facing the recording surface of the disk, and extends from the tip of the suspension 28 to the middle of the arm 26. An FPC connecting portion (not shown) for connecting to a main FPC 17 (see FIGS. 1 to 3) described later is provided at the base end portion of the relay FPC 32-i. The FPC connection portion of the relay FPC 32-i is connected to the end portion of the head wiring pattern 320-i and extends outward from the arm 26. The head 35 shown in FIGS.
-0, 35-1, 35-2, and 35-3 are actually sliders, and the original head is formed at a predetermined position of the slider, but here, for convenience of drawing, the slider is It shall represent the head.

The actuator 13 is, as shown in FIG. 2, a bearing assembly 22 and a support frame 25 attached to the bearing assembly 22 and extending in a direction opposite to the arms 26 of the HSAs 20-0 to 20-3. And this support frame 2
5 and a voice coil 240 integrally embedded in the same. The bearing assembly 22 is fixed on the bottom wall of the case 10 shown in FIG. 1 that functions as a base. The voice coil 240 is located between the top yoke 241 shown in FIG. 1 and a bottom yoke (not shown), and the VCM together with the permanent magnets (not shown) fixed to the both yokes and the bottom yoke.
Make up 24. Each HSA 20-i is attached to the bearing assembly 22 by inserting the hub of the bearing assembly 22 into the through hole 30 (see FIG. 3) of the arm 26, and the bearing assembly 2 is attached by the VCM 24 having the voice coil 240.
It is rotated around 2. By rotating each HSA 20-i, the MR supported at the tip of the suspension 28
The head 35-i is moved substantially along the radial direction of the disk 11-j (j = 0, 1).

Relay FP provided in each HSA 20-i
All of the C32-i FPC connections are board units 15
It is electrically and mechanically connected to the FPC connection portion 170 of the main FPC 17 extending from the. Main FPC17
Above is the head wiring pattern 3 on each relay FPC 32-i.
Head wiring patterns 171-i connected in parallel with 20-i via the FPC connecting portion are formed in parallel. Main FPC
A VCM wiring pattern 172 connected to the VCM 24 is also formed on 17. Main FPC17
A ground wiring pattern (hereinafter referred to as a GND wiring pattern) 173 is also formed on the top. A through hole (not shown) is formed at the tip of the main FPC 17 to penetrate the tip of the GND wiring pattern 173. The tip of the main FPC 17 is fixed to the bearing assembly 22 of the actuator (carriage) 13 by a conductive screw 174 through the through hole. As a result, GND
The potential of the wiring pattern 173 is basically at the same level as the bottom wall of the case 10 (as a base) to which the bearing assembly 22 is fixed. Here, the wiring patterns are arranged from the top in the wiring patterns 171-0, 171-1, 171.
The order is -2, 171-3, 173, 172. The GND wiring pattern 173 has head wiring patterns 171-0 to 171-3 in order to realize a function as an electrical shield.
And the VCM wiring pattern 172.
That is, the GND wiring pattern 173 is provided for the purpose of preventing the induced current from flowing through the head wiring patterns 171-0 to 171-3 when a spike-shaped current flows through the voice coil 240 of the VCM 24. .

The board unit 15 has a board body 150 fixed on the bottom wall of the case 10.
A connector 156 and the like for connecting the main PCB with the connector are mounted adjacently to 0. Main FPC1
7 is a board main body 1 made of a flexible printed circuit board.
It is formed integrally with 50. That is, the substrate body 15
It can be said that 0 is a fixed part of the main FPC 17.

Now, the MR head 35-i is caused by static electricity.
Considering the case where the breakdown of (i = 0 to 3) occurs, the present inventor has come to recognize that there are mainly three routes of the static electricity, as shown in FIG. In the first path, static electricity is on the substrate unit 15 (see FIG. 2) side and VC side.
Arrow 4 from the voice coil 240 side of M24 (see FIG. 2)
1 and 42 are paths (electrical paths) applied to the VCM wiring pattern 172, and static electricity applied to the VCM wiring pattern 172 is applied to the head wiring patterns 171-i and 320-i (see FIG. 4). In the example, the head 35-i is affected via i = 3). In the second path, static electricity is transferred from the case 10 (see FIG. 1) as a base via the bearing assembly 22 as shown by an arrow 43 to the head wiring patterns 171-i, 320-i (in the example of FIG. 4, i = 3). The third route is a route in which static electricity is directly applied to the head wiring patterns 171-i and 320-i (i = 3 in the example of FIG. 4) as shown by an arrow 44. However, the probability that static electricity is applied through the third path is lower than the probability that static electricity is applied through the first or second path. When static electricity is applied through the first or second path, the static electricity is applied to the head wiring pattern closer to the VCM wiring pattern 172 or the position closer to the case 10, that is, the head wiring patterns 171-3 and 320-3. Is likely to be applied. Therefore, the probability that the heads 35-0 to 35-3 will be destroyed by static electricity depends on the head wiring pattern 171.
The head 35-3 corresponding to -3 and 320-3 is the highest, and the heads are lower in the order of head 35-2 → head 35-1 → head 35-0.

Therefore, in this embodiment, between the static electricity path shown in FIG. 4 and the head 35-3 closest to the path,
As shown in FIGS. 2 and 3, a static electricity sensor 40 for detecting static electricity is provided. Specifically, as shown in FIG. 3, the relevant FPC on the surface of the main FPC 17 is
The electrostatic sensor 40 is provided at the tip end 17 side and near the head wiring pattern 171-3. Therefore, a sensor wiring pattern 175 connected to the electrostatic sensor 40 is formed on the main FPC 17. The electrostatic sensor 40 applied in the present embodiment is composed of, for example, a thin film resistor having two terminals.
The electrostatic sensor 40 is preset so as to be destroyed by a lower level of static electricity than the MR heads 35-0 to 35-3 (the MR elements constituting the MR heads). That is, the electrostatic sensor 40 is a kind of destructive sensor. Here, the width of the thin film resistor forming the electrostatic sensor 40 is set to the head 3
5-0 to 35-3, the electrostatic sensor 40 is made thinner than the MR element (MR film) constituting the MR heads 35-0 to 35-3.
Compared to -3, it is more susceptible to electrostatic damage.

FIG. 5 mainly shows the circuit configuration of an HDD having the internal structure of FIG. In FIG. 5, the SPM 12 and the VCM 24 are driven by drive currents respectively supplied from the motor driver (driver IC) 51. A value (control amount) for determining the drive currents supplied from the motor driver 51 to the SPM 12 and the VCM 24, respectively.
Is determined by the CPU 57.

Each head 35-0 to 35-3 is a head IC 52.
Connected with. Although not shown in FIGS. 1 to 3, the head IC 52 is assumed to be mounted on the main FPC 17. The head IC 52 is the head 35-0 to
35-3 is a head amplifier circuit that is made into one chip and includes a read amplifier that amplifies the read signal read by 35-3 and a write amplifier that converts write data into a write current.

The head IC 52 is connected to a read / write channel (hereinafter referred to as R / W channel) 53. The R / W channel 53 has various types of A / D (analog / digital) conversion processing, write data encoding processing, read data decoding processing, etc. for the amplified read signal (analog signal) output from the head IC 17. Signal processing of. The R / W channel 53 also extracts information (servo information) necessary for positioning the head 35-i from the read signal and outputs it to the gate array (ASIC) 54.

The gate array 54 includes an R / W channel 53.
A head position signal necessary for positioning the head 35-i is detected from the servo information extracted by. This head position signal is sent to the CPU 57 and used for control for positioning the head 35-i at the target position. The gate array 54 also has an interface function for controlling command and data communication with a host using the HDD, and an R function.
A disk controller function for controlling data communication with the / W channel 53, and a buffer controller function for controlling a buffer RAM 55 in which data to be transferred to the host and data to be transferred to the R / W channel 53 are temporarily stored. Have. The gate array 54 also has a function of inputting the detection output of the electrostatic sensor 40 via the sensor amplifier circuit 56, converting it into digital data, and setting it in a specific register (not shown) readable by the CPU 57.

The sensor amplifier circuit 56 includes an amplifier 561 as shown in FIG. The amplifier 561 includes an input connected to one end of the electrostatic sensor 40 and the sensor 4
It has two inputs, one connected to the other end of 0. To connect the electrostatic sensor 40 and the sensor amplifier circuit 56, the sensor wiring pattern 1 on the main FPC 17 is connected.
75 is used. One input of the amplifier 561 is connected to the power supply voltage Vcc via the pull-up resistor 562,
The other input of the amplifier 561 is grounded. As the pull-up resistor 562, a resistor having a resistance value sufficiently higher than that of the thin film resistor forming the electrostatic sensor 40 is used.

Referring again to FIG. 5, the CPU 57 contains a non-volatile memory in which a control program is stored, for example, a rewritable FROM (flash ROM) 58. The CPU 57 controls each unit in the HDD according to the control program stored in the FROM 58. C
The control realized by the PU 57 executing the control program includes the well-known control for positioning the head 35-i at the target position on the disk 11-j based on the head position signal sent from the gate array 54. ing. CP
In addition to controlling each unit in the HDD, the U57 also monitors the detection output of the electrostatic sensor 40 via the gate array 54, and more specifically, the electrostatic sensor 40 will be described.
It is configured to determine (detect) an excessive application of static electricity to the head 35-i by monitoring the conduction state of.

Next, regarding the operation of this embodiment, the head 3
The state of static electricity applied to 5-0 to 35-3 is indicated by the static electricity sensor 4
The case of monitoring by the conduction state of 0 will be described as an example. First, check if static electricity is not applied to the static electricity sensor 40.
Even if static electricity is applied, if the static electricity amount is at a low level, the static electricity sensor 40 is not destroyed. In this state,
The resistance value of the thin film resistor forming the electrostatic sensor 40 is sufficiently lower than that of the pull-up resistor 562 of the sensor amplifier circuit 56. Therefore, the input level of the amplifier 561 in the sensor amplifier circuit 56 connected to the electrostatic sensor 40 is close to the GND level (ground level).

On the other hand, static electricity is applied to the heads 35-0 to 35-3 through the path as shown in FIG. 4, so that static electricity is also applied to the static electricity sensor 40 provided on the path. If so, the static electricity sensor 40 may be destroyed depending on the magnitude of the static electricity. When the electrostatic sensor 40 is destroyed, the electrostatic sensor 40 becomes non-conductive, and the input level of the amplifier 561 rises from the GND level to almost the Vcc level.

Therefore, by monitoring the output of the amplifier 561, it is possible to detect whether or not the static electricity sensor 40 is broken, that is, whether or not dangerous static electricity is applied to the heads 35-0 to 35-3. Therefore, in the present embodiment, the amplifier 5
The output level of 61 is set to A / (not shown) in the gate array 54.
The amplifier 561 is operated by, for example, periodically performing an operation of converting the digital value into a digital value by the D converter and setting the digital value in a specific register readable by the CPU 57.
The output level of is monitored by the CPU 57. The CPU 57, for example, starts up the HDD and / or HD
The set value of the specific register in the gate array 54 is read periodically (for example, every minute) during the operation period of D. Then, the CPU 57 determines whether or not the electrostatic sensor 40 is broken, depending on the read value, that is, whether or not the output level of the amplifier 561 exceeds the threshold value. The CPU 57 determines whether or not the static electricity applied to the heads 35-0 to 35-3, particularly the head 35-3, is detected by the static electricity sensor 40 based on the determination result of whether or not the static electricity sensor 40 is destroyed. It is recognized whether or not the voltage is applied to the head.

When the CPU 57 determines that the static electricity applied state that may damage the heads 35-0 to 35-3 is detected by the static electricity sensor 40, the detection result is used as one of data for failure prediction. , Disks 11-0, 1
The operation of storing in at least one of the system areas (not shown) which is secured in advance on each recording surface 1-1 is performed. The system area is a ring-shaped non-user area used only by the system, that is, invisible to the user. Here, the specific position on the system area is previously assigned to the storage position of the specific parameter (system parameter) indicating the detection result of the static electricity application state by the static electricity sensor 40. The CPU 57 saves the detection result of the static electricity application state by the static electricity sensor 40 by controlling (turning on) the specific parameter (flag) to a predetermined value. Data for predicting a failure in the system area can be read into the host by a dedicated command from the host.

The host, for example, the electrostatic sensor 4 is activated when the host starts up or periodically when the host is in an operating state.
A specific command is issued to the HDD to request notification of the detection result of the static electricity application state by 0. CPU 57 in HDD
When the above-mentioned specific command is given from the host, the specific parameter stored in the specific position in the system area of the disk 11-0 or 11-1 is read, and the static electricity applied state by the electrostatic sensor 40 indicated by the parameter is read. Notify the host of the detection result.

When the CPU 57 saves the detection result of the static electricity applied state by the static electricity sensor 40 by setting the above-mentioned specific parameter to a predetermined value, an interrupt is generated from the gate array 54 to the host under the control of the CPU 57, You may make it require a host to read the said specific parameter.

In addition to this, when the specific command is given from the host to the HDD, the CPU 57 causes the gate array 5 to operate.
It is also possible to read the setting value of the specific register in 4 to determine the static electricity application state and notify the host of the determination result as the detection result of the static electricity application state by the static electricity sensor 40. In addition, the specific parameters
-FROM5, not the system area of 0 or 11-1
You may make it write in the specific area in 8.

When the host detects that the static electricity applied state by the static electricity sensor 40 notified from the HDD indicates that static electricity that may damage the heads 35-0 to 35-3 is applied, It is determined that the static electricity may have damaged the heads 35-0 to 35-3. In this case, the host will
A warning that a failure of D may occur is presented to the user through, for example, a display screen, and a backup of the data stored in the HDD is urged.

As described above, in this embodiment, the electrostatic sensor 40 composed of the thin film resistor having a structure that is more easily destroyed by the application of static electricity than the heads 35-0 to 35-3 is
The heads 35-0 to 35-35 are provided by providing the path between the static electricity and the head 35-3 closest to the path in the DD.
-Because static electricity that may damage -3 was applied, before the heads 35-0 to 35-3 were actually destroyed,
It is possible to detect with high sensitivity by breaking the electrostatic sensor 40. In addition, by notifying the host of this state from the HDD (gate array 54 therein), the host sends H
Since the backup of the data stored in the DD can be promoted, important data will be lost even if one of the heads 35-0 to 35-3 is subsequently destroyed by static electricity being frequently applied. It can be prevented from doing.
In addition, in the present embodiment, the electrostatic sensor 40 is a destructive electrostatic sensor composed of a thin film resistor that is destroyed (cut) when static electricity of a reference level or higher is applied. Therefore, even when static electricity of a reference level or higher is applied through the case 10 in the non-operating state of the HDD, the static electricity sensor 40 is destroyed, and the heads 35-0 to 35-3 are damaged. It can be easily determined that there was a possibility.

[First Modification] Next, the first modification of the present embodiment will be described.
A modified example will be described. The feature of the first modification is that the electrostatic sensor 40 is a non-destructive electrostatic sensor having a structure similar to that of a capacitor, instead of the destructive electrostatic sensor composed of the thin film resistor applied in the above embodiment. That is, a capacitor type non-destructive electrostatic sensor is used. The voltage across the terminals of this capacitor-type non-destructive electrostatic sensor is proportional to the amount of charge accumulated when static electricity is applied. It can be detected including.

In the first modified example in which a capacitor-type nondestructive electrostatic sensor is used as the electrostatic sensor 40, as shown in FIG.
Instead of the sensor amplifier circuit 56 having the above structure, a sensor amplifier circuit 56 'having the structure shown in FIG. 7 is used. The sensor amplifier circuit 56 ′ includes a reset switch 563 that forcibly discharges the electric charge accumulated in the electrostatic sensor 40, a high input resistance type amplifier 564 that amplifies the electric potential of the electrostatic sensor 40, and has a very high input resistance value. And a comparator 565. The reset switch 563 is turned on / off by a control signal 566 from the gate array 54.
The comparator 565 compares the output potential of the amplifier 564 with the threshold potential 567 to output a static electricity detection signal 568 indicating whether or not the static electricity sensor 40 has accumulated a charge above a certain level. The threshold potential 567 is C
It can be variably set via the gate array 54 according to an instruction from the PU 57. In addition, the static electricity detection signal 568
Can be monitored from the CPU 57 via the gate array 54.

Next, regarding the operation of the first modification in which a capacitor-type nondestructive electrostatic sensor is applied to the electrostatic sensor 40, a flow chart for explaining the processing procedure of the gate array 54 shown in FIG. 8 and FIG. CPU5 shown
An explanation will be given by appropriately referring to a flowchart for explaining the processing procedure of No. 7.

First, for example, when the HDD is activated, the gate array 54 sends the control signal 56 to the sensor amplifier circuit 56 '.
6 is output to turn on the reset switch 563 (step S1). When the reset switch 563 is turned on (closed), the terminals of the electrostatic sensor 40 are short-circuited, and the electric charge accumulated in the electrostatic sensor 40 up to that point is immediately (forced) discharged. After the reset switch 563 is turned on, the gate array 54 resets the reset switch 5 when a first constant time required for discharging the charge accumulated in the electrostatic sensor 40 elapses.
63 is turned off (opened) (step S2). In this state, the gate array 54 takes in the binary state of the static electricity detection signal 568 from the sensor amplifier circuit 56 'after the lapse of the second constant time (step S3), and thereafter turns on (closes) the reset switch 563 (closed). Step S1)
On a regular basis (here, the disks 11-0, 11-1
Every 1 rotation). Here, the first fixed time <<
The second constant time, which is the first constant time + the second constant time≈one rotation time of the disks 11-0 and 11-1.

The inter-terminal voltage V of the capacitor type non-destructive electrostatic sensor 40 is proportional to the charge Q accumulated in the electrostatic sensor 40 by the static electricity applied to the electrostatic sensor 40, and the capacitance of the sensor 40. When (capacity) is C, it is represented by V = Q / C. In this embodiment, one end of the electrostatic sensor 40 is grounded. Therefore, the potential at the other end of the electrostatic sensor 40 matches the voltage V across the sensor 40. The high input resistance type amplifier 564 in the sensor amplifier circuit 56 ′ amplifies the potential of the other end of the electrostatic sensor 40. Comparator 56
5 designates the amplified output potential of the amplifier 564 as the threshold potential 56.
7, the effective static electricity detection signal 568 of logic “1”, for example, is output only while the amplified output potential of the amplifier 564 exceeds the threshold potential 567.

The gate array 54 includes the sensor amplifier circuit 5
Electrostatic detection signal 56 from comparator 565 in 6 '
The binary state of 8 is fetched for each rotation of the disks 11-0 and 11-1 (step S3), set in a specific register in the gate array 54 (step S4), and then the reset switch 563 is turned on again. Allow (Step S
1). As is apparent, the static electricity detection signal 568 indicates that the amount of electric charge accumulated in the static electricity sensor 40 by the static electricity applied to the static electricity sensor 40 within a certain period (the period in which the disks 11-0 and 11-1 make one revolution). , Threshold potential 567
It indicates whether or not the charge amount is larger than the threshold charge amount determined by (and the capacitance of the electrostatic sensor 40), that is, whether or not an abnormal state in which static electricity of a reference level or higher is applied to the electrostatic sensor 40 is detected.

On the other hand, the CPU 57 sets the two variables n and c to initial values 0 after a certain time (for example, a period in which the disks 11-0 and 11-1 make one revolution) after the HDD is activated (step S1). S11). The variable n is the gate array 5
2 of the static electricity detection signal 568 from the specific register in 4
This is a counter value that indicates the number of times the value state has been read.
Is a counter value indicating the number of times the read binary state is “1”.

Next, the CPU 57 accesses a specific register in the gate array 54 to make a sensor amplifier circuit 56 '.
The binary state of the static electricity detection signal 568 is read (step S12). Further, the CPU 57 uses the static electricity detection signal 5
Every time the 68 binary states are read, the binary state is "1".
It is determined whether or not (step S13).

Only when the read binary state is "1", the CPU 57 increments the variable c by 1 (step S14), and proceeds to step S15. On the other hand, when the read binary state is "0", the process directly proceeds to step S15. CPU57 is step S
After incrementing the variable n by 1 at 15, it is determined whether the value of n after the increment exceeds the threshold value ns (step S16). Here, the value of ns is 100, for example. If the value of n does not exceed ns, the CPU 57 returns to the process of step S12.

On the other hand, if the value of n exceeds the threshold value ns, the CPU 57 repeats the processing of steps S12 to S15 a predetermined number of times ns, so that it is determined that a certain time has elapsed after the execution of step S11. It is determined whether or not the current value of the variable c exceeds the threshold value cs (step S17). If the value of c exceeds cs, the CPU 57 frequently applies static electricity of the reference level or higher to the electrostatic sensor 40 within the above-mentioned fixed time, and therefore the heads 35-0 to 35-3 also have the reference. It is determined that the level of static electricity or more is applied and the warning to the host is necessary (step S18). In this case, C
The PU 57 sets the specific parameter in the system area to a predetermined value (turns on) to destroy the heads 35-0 to 35-3 in the same manner as when the PU 57 determines the breakdown of the electrostatic sensor 40 in the above embodiment. It is recorded that the static electricity application state that may occur is detected (step S1
9) and proceeds to step S21. On the other hand, the value of c is c
If it does not exceed s, the CPU 57 is less likely to apply static electricity of the reference level or higher to the static electricity sensor 40,
Therefore, it is determined that static electricity above the reference level has not been applied to the heads 35-0 to 35-3 (step S
20). In this case, the CPU 57 directly proceeds to step S2.
Go to 1. In step S21, the CPU 57 determines whether or not the ending condition is satisfied, and if the ending condition is not satisfied, the CPU 57 executes the processing in step S11 and thereafter again. On the other hand, if the ending condition is satisfied, the CPU 57 ends the series of processes from step S11. Here, the termination condition is, for example, when the HDD is changed from the operating state to the non-operating state, or after the HDD is activated, the determination of static electricity application (steps S17, S18 or S17, S20) is executed a predetermined number of times. Such is the case.

The operation of the host in the first modification is similar to that of the above-mentioned embodiment. That is, the host issues the specific command to the HDD at the time of starting itself or periodically when the host is in the operating state. CPU5 in HDD
7 is, when the above-mentioned specific command is given from the host,
A specific parameter stored at a specific position in the system area of the disk 11-0 or 11-1 is read out, and the host is notified of the detection result of the static electricity application state by the electrostatic sensor 40 indicated by the parameter. In the near future, if the host indicates that static electricity, which may damage the heads 35-0 to 35-3, is applied by the detection result of the static electricity application state by the static electricity sensor 40 notified from the HDD, The user is informed that a HDD failure may occur through a display screen or the like, and urges the user to back up the data stored in the HDD.

According to the first modification described above, since the electrostatic sensor 40 is the non-destructive electrostatic sensor of the capacitor type, the heads 35-0 to 35-3 are used.
The application of static electricity that damages 5-3 can be detected any number of times. However, since the electric charge accumulated in the non-destructive electrostatic sensor is naturally discharged, unlike the destructive electrostatic sensor applied in the above-described embodiment, the static electricity applied when the HDD is in a non-operating state cannot be detected.

Further, in the first modification, it is determined whether or not static electricity that damages the heads 35-0 to 35-3 is applied depending on the frequency at which static electricity of a reference level or higher is applied to the static electricity sensor 40. Since the determination is made, it is possible to prevent the application of static electricity from being erroneously determined due to the influence of noise.

In the first modification, when the value of the variable c, that is, the number of times static electricity having a level higher than the reference level is applied to the electrostatic sensor 40 exceeds the threshold value cs, the specific parameter is set to a predetermined value. By setting, heads 35-0 to 35
It records that static electricity that damages -3 was applied, but it is not limited to this. For example, after repeating a series of processes from step S11 for ns times, the value of the variable c at that time, that is, ns times of inspection, when static electricity of a reference level or higher is applied to the electrostatic sensor 40 (within a fixed time). The determined number of times itself or the cumulative value of the number of times may be recorded as data for failure prediction or the like.

In addition, the user can operate the HDD from the host.
On the other hand, it is also possible to variably set the threshold potential 567 for detecting an abnormality or the threshold value cs for issuing a warning. In addition, at the shipping stage of the HDD, under a constant noise environment, the threshold potential 567 is sequentially increased from a low potential, and the threshold potential 567 at which the static electricity detection signal 568 becomes logical “0” is obtained, and the It is also possible to determine the threshold potential 567 used in the HDD after shipping the HDD from the threshold potential. In this way, the threshold potential 567 can be set appropriately, so that when the static electricity detection signal 568 becomes a logic "1", that is, when the output of the amplifier 564 exceeds the threshold potential 567, the head is immediately returned. It is also possible to determine that static electricity that damages 35-0 to 35-3 is applied.

[Second Modification] Next, the second modification of the present embodiment will be described.
A modified example will be described with reference to FIG. The second modification is characterized in that the electrostatic sensor 4 is used as shown in FIG.
0 is a relay FP including a head wiring pattern 320-3 connected to the MR head 35-3 instead of on the main FPC 17.
It is located on the C32-3. Here, the electrostatic sensor 40 is provided on the relay FPC 32-3 corresponding to the suspension 28 of the HSA 20-3. Therefore, a sensor wiring pattern 321 connected to the electrostatic sensor 40 is formed on the relay FPC 32-3. The sensor wiring pattern 321 is connected to the sensor wiring pattern 175 on the main FPC 17.

Also in the second modification, since the electrostatic sensor 40 is provided between the static electricity path shown in FIG. 4 and the head 35-3 closest to the path, the heads 35-0 to 35-0. It is possible to reliably detect the application of static electricity that damages the head 35-3, especially the head 35-3. The electrostatic sensor 40 may be provided on the relay FPC 32-3 corresponding to the arm 26 of the HSA 20-3.

In the above embodiment and the first and second embodiments, the case where the electrostatic sensor 40 is provided separately from the heads 35-0 to 35-3 has been described, but the present invention is not limited to this. For example, it is possible to mount the electrostatic sensor 40 instead of the head 35-3. An HDD to which such a configuration is applicable will be described below. First, HDDs may have a plurality of types of models having the same basic structure but different numbers of data surfaces on which data can be actually recorded, that is, a plurality of types of models in the same series. This applies, for example, when manufacturing a three-head model or a two-head model HDD in the same series as the four-head model HDD. In this type of three-head model or two-head model HDD, a dummy head of the same weight is usually mounted on the corresponding head. Therefore, for example, instead of the dummy head of the head 35-3, the electrostatic sensor 40
It is also possible to install.

The case where the present invention is applied to an HDD (magnetic disk device) has been described above, but the present invention is an HDD in which at least information is read by the head.
Other disk storage devices, such as magneto-optical disk devices,
It is also applicable to a disk storage device such as a flexible disk device.

The present invention is not limited to the above-described embodiments and modifications thereof, but can be variously modified at the stage of implementation without departing from the scope of the invention.
Furthermore, the above-described embodiments or modifications include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and the effect described in the section of the effect of the invention can be solved. When the above is obtained, the configuration in which this constituent element is deleted can be extracted as the invention.

[0066]

As described in detail above, according to the present invention, an electrostatic sensor composed of a thin film resistor or a capacitor type electrostatic sensor can be used to predict head breakage due to static electricity before causing head breakage. Therefore, it is possible to avoid the loss of important data due to the fact that the data cannot be read from the disk medium due to the head destruction, and the reliability of the disk storage device can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an internal structure of a magnetic disk device (HDD) according to an embodiment of the present invention.

2 is a main FPC 1 fixed to an actuator 13 and a bearing assembly 22 of the actuator 13 in FIG.
7 is a perspective view of FIG.

FIG. 3 is a main FPC 17 and relay FPCs 32-0 to 32.
3 is a diagram showing the relationship between the wiring pattern position on the −3 and the position of the electrostatic sensor 40. FIG.

FIG. 4 is a diagram for explaining static electricity paths in the HDD of FIG.

5 is a block diagram showing a circuit configuration of the HDD of FIG.

6 is a diagram showing a configuration of a sensor amplifier circuit 56 in FIG. 5 when the electrostatic sensor 40 is a destructive electrostatic sensor.

FIG. 7 is a diagram showing a configuration of a sensor amplifier circuit 56 ′ used in place of the sensor amplifier circuit 56 in the first modified example of the embodiment in which a nondestructive electrostatic sensor is used as the electrostatic sensor 40.

FIG. 8 is a flowchart for explaining a processing procedure of the gate array 54 in the first modified example.

FIG. 9 is a flowchart for explaining a processing procedure of a CPU 57 in the first modified example.

FIG. 10 is a diagram for explaining a second modified example of the above embodiment in which the electrostatic sensor 40 is arranged on the relay FPC 32-3.

[Explanation of symbols]

10 ... Case (base) 11-0, 11-1 ... Disk (disk medium) 12 ... SPM (spindle motor) 13 ... Actuator 17 ... Main FPC (flexible printed circuit board) 22 ... Bearing assembly 24 ... VCM (voice) Coil motor) 26 ... Arm 28 ... Suspension 32-0 to 32-3 ... Relay FPC 35-0 to 35-3 ... Head 40 ... Electrostatic sensor 54 ... Gate array 56 ... Sensor amplifier circuit 57 ... CPU (detection means, notification means) ) 171-0 to 171-3, 320-0 to 320-3 ... Head wiring pattern 172 ... VCM wiring pattern 173 ... GND wiring pattern 174 ... Screws 175, 321 ... Sensor wiring pattern 563 ... Reset switch (discharging means) 565 ... Comparator (comparing means)

Claims (9)

[Claims] 1. A disk storage device in which at least information is read by a head, and is composed of a thin film resistor that is weaker than the head to electrostatic breakdown and is destroyed by application of static electricity exceeding a reference level to be in a non-conductive state. A static electricity sensor equipped with a static electricity sensor and means for monitoring the conduction state of the static electricity sensor and detecting that static electricity exceeding a reference level is applied to the head according to the monitoring result. Disk storage device. 2. In a disk storage device in which at least information is read by a head, a capacitor type electrostatic sensor and a potential of the electrostatic sensor reflecting the amount of electric charge accumulated in the electrostatic sensor by application of static electricity are monitored. And a means for detecting that static electricity exceeding a reference level is applied to the head according to the monitoring result, and a disk storage device equipped with a static electricity sensor. 3. The apparatus further comprises means for forcibly discharging the electric charge accumulated in the electrostatic sensor, wherein the detection means is configured to detect static electricity exceeding the reference level in the head after the electric charge is discharged by the discharging means. 3. The detection operation of application is performed.
A disk storage device equipped with the described electrostatic sensor. 4. The apparatus further comprises means for comparing the potential of the electrostatic sensor with a predetermined reference potential, wherein the detecting means monitors the potential of the electrostatic sensor according to the comparison result of the comparing means, and The static electricity according to claim 2, wherein when the potential of the static electricity sensor indicates that the potential exceeds the reference potential, it is detected that static electricity exceeding the reference level is applied to the head. Disk storage device equipped with a sensor. 5. The electric potential of the electrostatic sensor further comprises means for comparing the electric potential of the electrostatic sensor with a predetermined reference electric potential, wherein the detecting means periodically checks the comparison result of the comparing means. Is measured to measure the number of times that the potential of the electrostatic sensor exceeds the reference potential within a fixed time, and when the number of detections exceeds a predetermined reference number, the head The disk storage device equipped with an electrostatic sensor according to claim 2, wherein it is determined that static electricity exceeding the reference level is applied. 6. When the detection means detects that static electricity exceeding the reference level is applied to the head, it further comprises means for notifying the host using the disk storage device of that fact. A disk storage device equipped with the electrostatic sensor according to claim 1 or 2. 7. A head suspension assembly including at least one disk medium having two surfaces, at least one of which is a recording surface, and a suspension supporting the head, the suspension extending from an arm. There
An actuator in which head suspension assemblies respectively arranged corresponding to the recording surfaces of the at least one disk medium are rotatably stacked on the disk medium, and a flexible printed circuit having a tip end fixed to the actuator. A substrate is further provided, and the electrostatic sensor is disposed on a tip end portion of the flexible printed circuit board or a lowermost head suspension assembly of the stacked head suspension assemblies. A disk storage device equipped with the electrostatic sensor according to claim 1. 8. A method of detecting static electricity application in a disk storage device in which at least information is read by a head, which is weaker than the head to electrostatic breakdown and is destroyed by application of static electricity exceeding a reference level to be in a non-conductive state. Detecting that the electrostatic sensor is in a non-conducting state as a result of monitoring the conducting state of the electrostatic sensor, which is composed of a thin film resistor and is arranged in the vicinity of the head, and monitoring the conducting state of the electrostatic sensor. If
A step of determining that static electricity exceeding a reference level is applied to the head, the method for detecting static electricity application in a disk storage device. 9. A method for detecting static electricity application in a disk storage device in which at least information is read by a head, the potential being a potential of a capacitor-type static electricity sensor arranged in the vicinity of the head, said static electricity being applied by application of static electricity. Monitoring the electric potential of the sensor reflecting the amount of electric charge accumulated in the sensor; and detecting the application of static electricity exceeding the reference level to the head according to the result of monitoring the electric potential of the electrostatic sensor. A method of detecting static electricity application in a disk storage device, comprising: