JP4220986B2 - Head load / unload control method and storage device - Google Patents

Description

  The present invention relates to a head load / unload control method and a storage device for retracting a head for reading a storage medium to the outside of the storage medium when unnecessary.

  Storage devices having a head for reading a storage medium are widely used. For example, a magnetic disk drive used as a storage device of a computer includes a magnetic disk, a head that reads / writes the magnetic disk, and a VCM actuator that positions the head on a track of the magnetic disk. 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, refer to Patent Document 1).

  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.

In response to this request, such a conventional storage device counts the continuation time when the access (input / output command) does not continue, and performs the above-described unloading operation when the continuation time reaches a predetermined time. Was evacuated from the magnetic disk. 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. When the access arrives, the head is loaded only during use by returning the head from the ramp member to the magnetic disk (referred to as loading).
JP-A-6-60578

  However, the prior art has the following problems.

  (1) In the prior art, the predetermined time from when access is lost to when unloading starts is fixed. This predetermined time is a short time (for example, 3 seconds) from a request to unload when unnecessary. For this reason, the unload operation is frequently performed. This unloading and loading operation has a problem that the lamp member and the head portion swing, so that the lamp member is easily worn and the life is short. In general, the ramp member is formed by a non-metal member such as a synthetic resin so as not to wear the metal member such as the head, and is therefore scraped by sliding. Since the surface of the ramp member is smooth in the initial stage, the generation of dust due to the peristaltic movement is small. This large dust adheres to the disk and head and frequently causes data errors. Before reaching such a state, it is necessary to set the lifetime of the lamp member. For example, it is said to be about 300,000 times. As described above, when loading / unloading is frequently performed in order to improve impact resistance, the life of the lamp member is reached quickly. In a small storage device such as a hard disk device, since the parts are extremely fine, it is almost impossible to replace only the lamp member. For this reason, when the lamp member reaches the end of its life, the apparatus itself has to be at the end of its life, and there is a problem that the life of the apparatus is shortened because the lamp member reaches the end of its life quickly.

  (2) In addition, since the predetermined time is a fixed value, there is a problem that the access time decreases depending on the use environment and access conditions.

  (3) Further, since the predetermined time is a fixed value, there is a problem that the effect of reducing the power consumption cannot be obtained depending on the use environment and the access situation.

  An object of the present invention is to provide a head load / unload control method and a storage device for performing an appropriate unload operation according to the situation of the apparatus.

  Another object of the present invention is to provide a head load / unload control method and a storage device for extending the life of the apparatus even in an unload operation.

  Still another object of the present invention is to provide a head load / unload control method and a storage device for preventing a reduction in access time even in an unload operation.

  Still another object of the present invention is to provide a head load / unload control method and a storage device for further reducing power consumption even in an unload operation.

  In order to achieve this object, the head load / unload control method according to the present invention includes a step of unloading the head to a position outside the storage medium when an access command does not arrive for a predetermined time, and the access Loading a head onto the storage medium upon arrival of a command, and changing the predetermined time according to the status of the apparatus.

  In this aspect, the predetermined time (unload start time), which has been a fixed value in the past, is made variable and changed according to the status of the apparatus. For this reason, an optimal unloading operation can be performed according to the status of the apparatus. That is, an unloading operation in which the apparatus life, access time, and impact resistance are balanced can be performed.

  The step of changing includes a step of changing the predetermined time in accordance with an output of a sensor that detects an impact. That is, since the predetermined time is changed according to the environment of the apparatus, the place where the apparatus is placed, the frequency of impact, and the like, it is possible to increase effects such as improvement in impact resistance, reduction in temperature rise, and reduction in power consumption.

  The storage device of the present invention includes a head that reads at least a storage medium, an actuator that positions the head, a ramp mechanism that is provided at a position outside the storage medium and supports the head, and a time when an access command does not arrive. Control means for unloading the head to a lamp position outside the storage medium and loading the head onto the storage medium upon arrival of the access command when the time continues. The predetermined time is changed according to the status of the device.

  In this aspect, the predetermined time (unload start time), which has been a fixed value in the past, is made variable and changed according to the status of the apparatus. For this reason, an optimal unloading operation can be performed according to the status of the apparatus. That is, an unloading operation capable of achieving both access time and impact resistance becomes possible.

  A sensor for detecting the impact of the apparatus is provided, and the predetermined time is changed according to the output of the sensor.

  Hereinafter, the present invention will be described by dividing it into a storage device and load / unload processing.

··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 substrate (disc). The magnetic disk 6 has a size of 2.5 inches, and three disks 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 fix 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 composed of a power amplifier 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.

  As shown in FIG. 1, the load / unload control is performed by the MPU 19. That is, the magnetic head 4 is positioned on the magnetic disk 6 during loading. When the unload command is received, the speed of the VCM 3 is controlled to the outer stopper position. The speed is detected from the back electromotive voltage of VCM3. As a result, the lift tab 12 is guided by the slope 11-1 of the ramp member 11, moves toward the recess 11-2, and is moved into the recess 11-2. 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.

  On the other hand, when the load command arrives, the VCM 3 drives the head 4 in the direction of the magnetic disk 6. For this reason, the lift tab 12 moves in the direction of the magnetic disk 6 by swinging the slope 11-1 from the recess 11-2 of the ramp member 11. 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, 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 load / unload process flow diagram according to the embodiment of the present invention, and FIG.

  (S1) When the input / output command processing is completed, the MPU 19 initializes an unload start timing counter Cnt to “0”.

  (S2) The MPU 19 determines whether an input / output command (read command, write command) has arrived from the host. When the MPU 19 determines that an input / output command has arrived, the MPU 19 proceeds to a command execution process in step S10.

  (S3) When the MPU 19 determines that an input / output command (read command, write command) has not arrived from the host, the MPU 19 increments the counter Cnt by “1”. The counter Cnt indicates a duration time during which no input / output command arrives.

  (S4) The MPU 19 determines whether the counter Cnt is greater than the unload start time B. If the counter Cnt is not greater than the unload start time B, the duration has not reached the start time, and the process returns to step S2.

  (S5) If the counter Cnt is greater than the unload start time B, the MPU 19 executes the unload because the duration has reached the start time. As described above, the counter electromotive voltage of the VCM 3 is detected, the speed is controlled, and the motor is driven to the outer position. Accordingly, as described above, the lift tab 12 is positioned in the recess 11-2 of the ramp member 11, and the head 4 is positioned at the position P0 in FIG. Since the lift tab 12 is located in the recess 11-2 of the ramp member 11, it is mechanically held, and there is no need to pass a drive current through the VCM 3.

  (S6) Next, the MPU 19 increments the unload execution count C by “1”. Further, it is determined whether the unload execution count C exceeds the setting change count D.

  (S7) If the unload execution count C exceeds the setting change count D, the unload start time B is changed to B (L).

  (S8) In this unload state, the MPU 19 determines whether an input / output command (read command, write command) has arrived from the host. When it has not arrived, it waits for a command from the host.

  (S9) In the unload state, when the MPU 19 determines that an input / output command has arrived, it executes a load process. That is, the MPU 19 drives the head 4 in the direction of the magnetic disk 6 by the VCM 3. The MPU 19 detects the speed from the back electromotive voltage of the VCM 3 and controls the speed of the VCM 3. Therefore, the lift tab 12 moves in the direction of the magnetic disk 6 from the recess 11-2 of the ramp member 11 via the slope 11-1. As a result, the magnetic head 4 returns to the magnetic disk 6.

  (S10) The MPU 19 executes the incoming input / output command. That is, the MPU 19 recognizes the position signal from the servo demodulation circuit 16, controls the VCM control current of the VCM drive circuit 13, and positions the magnetic head 4 on the designated track of the magnetic disk 6. The HDC 18 performs read / write operations on the magnetic disk 6 via the magnetic head 4. Then, the process returns to step S1.

  As shown in FIG. 7, the unload start time is set to a short “B” until the unload count reaches the setting change count D. For this reason, since the unloading is performed immediately if there is no command, the impact durability is large and the power consumption is reduced. Even if unloading is performed frequently as described above, as described above, the generation of dust from the lamp member 11 is small, and a stable read / write operation is possible.

  On the other hand, when the unload count exceeds the setting change count D, the unload start time is changed to a long “B (L)”. If no command continues for a long time, unloading will not start. For this reason, it is possible to prevent the unload operation from occurring frequently. As described above, when the lamp member 11 is worn out, dust is generated and reading / writing becomes difficult. Therefore, the unload frequency is reduced and the life of the apparatus is extended before the lamp member 11 is worn to such an extent that dust is generated. Even in this case, since the unloading operation is performed, impact durability and low power consumption can be maintained.

  In the above description, the unload start time is shown as a two-stage change, but it may be three or more stages. Further, although the degree of wear of the ramp member 11 is measured by the number of unloads, it may be the number of loads or the number of loads and unloads.

  FIG. 8 is a flowchart of load / unload processing according to another embodiment of the present invention, and FIG. 9 is an explanatory diagram of the operation thereof.

  (S11) When the input / output command processing is completed, the MPU 19 activates the commandless measurement timer A. Timer A indicates the duration during which no input / output command arrives.

  (S12) The MPU 19 determines whether an input / output command (read command, write command) has arrived from the host. When the MPU 19 determines that an input / output command has arrived, the MPU 19 proceeds to a command execution process in step S20.

  (S13) When the MPU 19 determines that an input / output command (read command, write command) has not arrived from the host, the MPU 19 determines whether the value of the timer A exceeds the unload forced start time tf (fixed value). The unload forced start time tf will be described with reference to FIG. When the value of the timer A exceeds the unload forced start time tf (fixed value), the process proceeds to step S15.

  (S14) The MPU 19 determines whether the value of the timer A is greater than the unload start set time ts. If the value of the timer A is not greater than the unload start set time ts, the duration has not reached the unload start set time, and the process returns to step S12.

  (S15) If the value of the timer A is greater than the unload start set time ts, the MPU 19 executes the unload because the duration has reached the start time. As described above, the speed of the VCM 3 is controlled and driven to the outer position. Thus, as described above, the lift tab 12 is positioned in the recess 11-2 of the ramp member 11, and the head 4 is positioned at the position P0 in FIG. Since the lift tab 12 is located in the recess 11-2 of the ramp member 11, it is mechanically held, and there is no need to pass a drive current through the VCM 3.

  (S16) Next, the MPU 19 stops the timer A. Then, by adding the current duration A, the average value ta (N) of the no-access duration is calculated by the following equation. In the following formula, Ls is the total number of unloads up to the previous time, and ta (N−1) is the average value of the previous no-access duration.

ta (N) = (ta (N−1) × Ls + A) / (Ls + 1)
Next, the unload start set time ts is calculated from the average value ta (N) by the following formula, and the unload start set time ts is updated.

ts = ta (N) −α
Or ts = ta (N) + β
The meaning of this equation will be described with reference to FIG.

  (S17) In this unload state, the MPU 19 determines whether an input / output command (read command, write command) has arrived from the host. When it has not arrived, it waits for a command from the host.

  (S18) In the unloaded state, when the MPU 19 determines that an input / output command has arrived, the MPU 19 executes loading. That is, the MPU 19 drives the head 4 in the direction of the magnetic disk 6 by the VCM 3. Therefore, the lift tab 12 moves in the direction of the magnetic disk 6 from the recess 11-2 of the ramp member 11 via the slope 11-1. As a result, the magnetic head 4 returns to the magnetic disk 6.

  (S19) The MPU 19 executes the incoming input / output command. That is, the MPU 19 recognizes the position signal from the servo demodulation circuit 16, controls the VCM control current of the VCM drive circuit 13, and positions the magnetic head 4 on the designated track of the magnetic disk 6. The HDC 18 performs read / write operations of the magnetic disk 6 via the magnetic head 4. Then, the process returns to step S11.

  In this embodiment, the unload start time is changed according to the average value of the no-access continuation time. Therefore, the unload operation is controlled according to the access status. As a result, the access time can be improved and the power consumption can be reduced even if the unload operation is performed. As shown in FIG. 9, when the set time ts is calculated by “ta (N) −α” in step S16, the unload start time is calculated before the next expected input / output command time (average value) ts. Is set. For this reason, since the probability of unloading increases regardless of access, power consumption is reduced and heat generation of the VCM can be prevented.

  On the other hand, as shown in FIG. 9, if the set time ts is calculated by “ta (N) + β” in step S16, the next I / O command time (average value) ts is not exceeded. Is not executed. Therefore, the head is on-track on the medium until the next expected input / output command time (average value) ts, and the access time can be shortened.

  The meaning of the unload forced start time tf (fixed value) described in step S13 will be described. As described above, when the unload start time is determined according to the average value of the no-access duration, if the average value of the duration is increased, there is a possibility that unloading is not performed for a long period. For this reason, by providing a fixed unload forced start time tf and forcibly unloading regardless of the average value of the no-access continuation time, it is possible to prevent unloading from being executed for a long period of time.

  Further, instead of the forced start time, an upper limit of the unload start time determined by the average value of the no-access continuation time can be provided, and the unload start time can be determined within the upper limit.

  FIG. 10 is an explanatory diagram of the unload start time according to still another embodiment of the present invention. FIG. 10 shows how the unload start time t changes as shown by a dotted line in accordance with the remaining battery charge L of a solid line personal computer or the like.

  As the battery capacity decreases, it is convenient to reduce the power consumption of each part in order to extend the battery capacity. For this reason, the unload start time t is shortened according to the remaining battery level. For this reason, unloading is frequently performed, and the battery consumption of the disk drive is reduced by unloading. For this reason, the battery can last longer.

  As this method, the MPU 19 may receive power supply capacity information from a control unit that monitors the power supply of the personal computer, and change the unload start time in the same manner as described above. Further, since the unloading is performed, the magnetic head can be prevented from being attracted even if the rotation of the magnetic disk is stopped. For this reason, the power consumption of the drive can be further reduced by stopping the magnetic disk.

  In order to further improve the impact resistance, it is desirable to change the unload time depending on the environment in which the device is subjected to an impact. For example, an acceleration sensor or an impact sensor is provided in the drive, the impact is sensed by the sensor, and the unload start time is shortened when an impact exceeding a specified value is frequently detected. As a result, an environment with a lot of impact is detected, unloading is performed frequently, and impact resistance is improved.

  Similarly, when used on a desk, the possibility of receiving an impact is low, and when used on a desk other than the desk (for example, when used during movement), the possibility of receiving an impact is low. The unload start time is changed according to such an installation situation. As this method, for example, an AC power source is used when used on a desk, and a DC power source is used when used outside the desk. For this reason, when used with an AC power supply, the unload start time is lengthened, and when used with a DC power supply, the unload start time is shortened. The MPU 19 receives information on the type of power supply from the control unit that monitors the power supply of the personal computer, and changes the unload start time in the same manner as described above. Thereby, impact resistance can be improved.

  Furthermore, as described above, in a device where the temperature of the VCM is a problem, a temperature sensor that detects the temperature of the drive is provided as an environment of the device, and the unload start time may be controlled according to the output of the temperature sensor. it can. In this way, the temperature rise of the VCM can be prevented, and the read / write performance can be kept constant while maintaining the impact resistance.

  In addition, by controlling the unload start time according to the environmental status of the apparatus, it is possible to perform unload control that can exhibit the required performance according to the status.

  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, the present invention has the following effects.

  (1) Since the unload start time, which has been a fixed value in the past, is made variable and changed according to the status of the device, an optimum unload operation can be performed according to the status of the device.

  (2) Since the predetermined time is changed according to the environment of the device, the place where the device is placed, the frequency of impact, etc., the impact resistance can be improved and the unload operation with a balanced device life can be performed.

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. It is a load / unload processing flowchart of an embodiment of the present invention. It is operation | movement explanatory drawing of the process of FIG. It is a load / unload process flowchart of other embodiment of this invention. It is operation | movement explanatory drawing of the process of FIG. It is explanatory drawing of the unload start time of further another embodiment of this invention.

Explanation of symbols

3 Actuator 4 Magnetic Head 5 Spindle Motor 6 Magnetic Disk 11 Lamp Member 19 MPU

Claims (4)

In a load / unload control method for a head of a storage device in which the head reads at least data from the storage medium in response to an access command,
Unloading the head to a position outside the storage medium when a time when the access command does not arrive continues for a predetermined time; and
Loading the head into the storage medium upon arrival of the access command;
And a step of changing the predetermined time in accordance with an output of a sensor for detecting an impact in order to monitor the status of the apparatus. A head for reading at least a storage medium;
An actuator for positioning the head;
A ramp member provided at a position other than the storage medium and supporting the head;
When the time when the access command does not arrive continues for a predetermined time, the head is unloaded to the ramp member provided at a position outside the storage medium, and when the access command arrives, the head is moved to the ramp member. Control means for loading to the storage medium;
In order to monitor the status of the device, it has a sensor that detects impact,
The control means includes
The storage device, wherein the predetermined time is changed according to the output of the sensor. The storage device of claim 2.
The control device detects an impact exceeding a specified value based on an output of the sensor, and changes the predetermined time. The storage device of claim 2.
The control unit detects that the impact exceeding a specified value is frequent based on the output of the sensor, and changes the predetermined time.

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