JP2002117616A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arbitrarily select first, second and third modes, including the mode of a quick mode for carrying out seeking and data read and write at a high speed, and a silent mode of carrying out the seek and data read and write at a low speed, with low electric power consumption and low noise. SOLUTION: This disk device has a motor for causing a recording medium to rotate, a motor drive circuit, a head movable to a prescribed position, a head drive mechanism and head drive circuit and a microprocessor for controlling the motor drive circuit and the head drive circuit. The operation mode relating to the seek moving speed of the head may be selected by the instruction from the higher position device accessibly connected to the disk device; and when the first, second or third operation mode is selected, the head drive circuit imparts first, second or third drive current to the head drive mechanism and the noise level of the disk device is lowered in order of the first, second or third operation mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive, and more particularly to a high-speed transfer / high-speed access mode in which a disk recording medium is rotated at a high speed and a head is moved at a high speed to perform seek and recording / reproduction (read / write), and disk recording. The present invention relates to a disk device having a low power consumption and low noise mode in which a medium is rotated at a low speed and a head is moved at a low speed to perform seek and recording / reproduction (read / write).

[0002]

2. Description of the Related Art Conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 2-156470 (Document 1), an audio signal such as a control signal TOC has been used in a compact disc (CD) or digital audio tape recorder (DAT). Automatically set a second speed faster than the normal voice signal reading speed for reading signals other than
There is known a playback device that is improved in operability.

FIG. 8 shows a schematic configuration of a disk device described in Japanese Patent Application Laid-Open No. 4-2095963 (Document 2). In FIG. 1, a magnetic disk drive 1 is a magnetic disk 2
, A disk drive motor 3, a magnetic head 5, a disk circuit section 13, and standby control means 14. The standby control means 14 performs the following operations. That is,
In addition to the normal operation mode (write / read mode) and the stop mode in which all power is turned off, the standby control unit 14 controls the I / F, the detection amplifier, When the power of the circuit unit 13 such as the head control circuit is turned off or in a standby state, and the disk drive motor 3 rotates at a normal speed, a first standby mode is continued. F, a detection amplifier, and a second standby mode in which the power of the circuit unit 13 such as the head control circuit is turned off or in a standby state and the disk drive motor 3 rotates at a low speed, thereby reducing power consumption. ing.

Further, as described in, for example, JP-A-63-87663 (Document 3), in a magnetic disk drive, if the next read / write start time is known in advance, the time from the start of seek to the start of read / write is determined. By detecting the waiting time and controlling the seek speed (moving speed) of the head so that the difference between the waiting time and the average seek time previously obtained for each moving distance of the head is almost zero,
There is a known head that avoids excessive acceleration and deceleration of the head and saves power during seeking.

[0005]

According to the prior art of the above-mentioned document 1, in a CD or DAT, an audio signal required by a user is reproduced at only one kind of normal speed, and a user such as a control signal is used. The unused signal is reproduced at a higher speed than the normal speed. No consideration is given to recording / reproducing arbitrary data used by the user at various medium speeds such as high speed, standard speed, and low speed according to the user's request, and to saving power consumption. Not.

Further, in the prior art of the above document 2, the power supply of the head control circuit is turned off in a standby mode (first and second standby modes) in which reading and writing (including seeking) is not performed, and a second standby mode is set. In the mode, the rotation speed of the disk drive motor is made lower than the normal speed, and the read / write speed is only the normal speed (one type).
No consideration is given to setting various reading / writing speeds of arbitrary data in accordance with a user's request.

However, first, in general, the frequency of occurrence of a state in which reading or writing is not performed is not always so high in a disk device, and generally, a state in which reading or writing is not performed is a non-operating state in which power is not turned on. Since the power consumption is the second lowest after the state (power consumption 0 W) (the highest power consumption is at the time of motor startup, and the second highest power consumption is at the time of file access. In both cases, reading and writing are performed while the motor is rotating). Even if the standby mode (second standby mode) is set and the disk motor speed is reduced in a state where the reading and writing are not performed, as described in Document 2, even if the disk motor speed is reduced, the overall power consumption is low. No reduction effect can be obtained. Rather, when the read / write state is divided in the second standby mode, it is necessary to start up the disk motor at the time of shifting from the standby mode to the write / read operation, so that large power is temporarily consumed.

Secondly, in Document 2, a problem arises in that the start-up of writing / reading is delayed and the operating speed is delayed since a start-up time of the motor is required when shifting from the standby mode to the writing / reading operation.

The prior art of Reference 3 adjusts the seek speed in accordance with the read / write start time known in advance so that the seek ends immediately before. There is no idea to use a high-speed seek capable of high-speed processing and a low-speed seek performed with low noise and low power in response to a user request. Also, in Reference 3, as in References 1 and 2, it is not possible to read and write arbitrary data at various read / write speeds such as high speed, standard speed, and low speed in response to a request from the user. Not even considered.

By the way, in the magnetic disk device and the optical disk device, the demand for the performance of the user can be roughly classified into two types as follows. To meet the performance of high-speed transfer, high-speed access, low power consumption and low noise, it is necessary to increase the read / write speed of the disk, that is, the rotation speed and the seek speed of the head. Rotation speed) and the seek speed of the head. These two performances are contradictory to each other, and there is no disk device that simultaneously satisfies the two performances at the same time, and there is only a model having one type of data read / write speed and seek speed. For this reason, the user must
Prepare at least one model for each device that satisfies each of the performance requirements, and adjust the usage conditions for each use (whether to use the device under the regulation of noise level or maximum power or to emphasize transfer / access speed). It is inevitable to select a magnetic disk device having suitable performance.

In this case, the following problem occurs. Even if the intended use conditions are not clear, a magnetic disk device with either performance must be selected. There is no other way than to repurchase or replace the magnetic disk drive when it is desired to switch to another performance during use due to changes in the use conditions. Performance cannot be switched in a timely manner depending on the usage. In particular, such a problem occurs in a disk device attached to a personal computer, such as a notebook personal computer, which shares a commercial AC power supply and a built-in battery power supply. In this type of personal computer, when using commercial power, sufficient power can be taken, so it is desirable to make the head seek speed and disk read / write speed sufficiently high when accessing files, while when using the built-in battery power, the system It is desirable that the head seek speed and the disk read / write speed be lowered and the power consumption be reduced in order to extend the continuous use time of the disk.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to perform a quick mode (high-speed transfer / high-speed access mode) for performing seek and data reading / writing at high speed.
At least two modes including a low-speed, low-power-consumption, low-noise mode and a silent mode (low-speed, low-power consumption, low-noise mode) for reading and writing data.
Another object of the present invention is to provide a disk device which can arbitrarily select any of the second, third, and third modes according to a user's request.

Another object of the present invention is to provide a disk device attached to a personal computer in which a commercial power supply and a built-in battery power supply are shared. When the commercial power supply is used, the above-mentioned quick mode is selected and the built-in battery power supply is used. In such a case, it is possible to provide a disk device having a switching function so that the silent mode is selected.

[0014]

In order to achieve the above object, the present invention is configured as follows.

(1) A disk drive for rotating a disk-shaped recording medium and moving a head toward a target position on the recording medium to record data on the recording medium or reproduce data from the recording medium, A head moving speed mode switching means for switching the moving speed in two or more steps, ie, three steps, and a medium rotating speed mode switching means for switching the rotating speed during recording or reproduction of the recording medium in two or more steps, ie, three steps. Things.

(2) In the above (1), the switching of the seek moving speed of the head and the switching of the rotation speed of the recording medium are performed by a command from a host device.

(3) In the above (1) or (2), the apparatus has a commercial power supply and a built-in battery power supply, and the head moving speed mode switching means and the medium rotation speed mode switching means use the commercial power supply. When the battery power is used, both the seek movement speed of the head and the rotation speed of the recording medium are switched to the low speed mode when the battery power is used. .

The operation based on the above configuration will be described.

According to the above configuration (1), the seek moving speed of the head and the rotational speed of the recording medium (disk) can be switched at two or more steps, respectively, so that the user can use only one disk device. If you want to write and read signals at high speed, you can write and read with the quick mode (the maximum speed of both the head and disk) selected. If you want to reduce power consumption with low noise, use the silent mode (head Writing and reading may be performed in a state in which both the minimum speed and the disk speed are selected. Since the operation mode can be selected in this manner, even if the use conditions are not determined in advance, the use conditions can be determined later and an operation mode suitable for the use conditions can be selected. There is no need to purchase the device, and the user can change the operation mode even during use according to the use conditions.

As a speed mode switching mechanism, in order to allow a user to freely select each mode at any time, as in the configuration of the above (2), the mode is controlled by a command from a higher-level device to a microprocessor in a disk device. If the switching is performed, the user can easily select a required mode by key operation or the like. Alternatively, each mode can be switched by a hardware switch such as a Japan connector provided on the head drive circuit and the disk motor drive circuit of the disk device.

According to the configuration (3), when a commercial power supply is used as a power supply for the personal computer and the disk device, the quick mode of high-speed reading / writing and high-speed seek is selected, and high-speed and high-performance data transfer / access is performed. When a built-in battery power supply is used, a low-speed read / write and low-speed seek silent mode is selected, and data transfer / access capable of continuous operation for a long time with low noise and low power consumption can be performed.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a magnetic disk drive according to a first embodiment of the present invention.

In FIG. 1, a disk drive 1 comprises a magnetic disk 2 as a recording medium, a motor 3 for rotating and supporting the disk 2, a head 5 for writing and reading signals to and from the disk 2, and a head drive mechanism 6. , A motor drive circuit 4 for driving the motor 3, and a head drive circuit 7 connected to the head drive mechanism 6. Both drive circuits 4, 7
Is connected to the microprocessor 8.

The microprocessor 8 has switches 9-1.
2, at least one switch is connected, and in the case of FIG. 1, four switches are connected. Various operation modes can be set by a combination of these switches as described later.

Two operation modes are set in the microprocessor 8, one of which has a motor rotation speed of 720.
A quick mode in which the seek movement time of the head is 8 ms at 0 rpm, and the other is a motor rotation speed of 540
0 rpm (current value at startup is the same as in quick mode),
This is a silent mode in which the seek movement time of the head is 10 ms (acceleration / deceleration is the same as in the quick mode). The quick mode is a mode that can realize high-speed transfer and high-speed access to the disk device, while the silent mode is a mode that can realize low power consumption and low noise.

These two modes can be selected by setting switches 9 to 12 connected to the microprocessor 8. For example, when the switch 9 is set to the off state, the operation mode is set to the quick mode, and when the switch 9 is set to the on state, the operation is performed in the silent mode. In FIG. 1, since four switches 9 to 12 are connected, up to 24 operation modes can be set by a combination of these switches. In the case of FIG. 1, the operation mode is set by switches 9 to 12 provided on a disk device such as a jumper switch, and cannot be set by a command from a higher-level device (system).

FIG. 2 is a schematic configuration diagram of a disk device according to a second embodiment of the present invention. This embodiment includes a drive circuit that switches the operation mode in accordance with an instruction from a higher-level device (system). It is.

In FIG. 2, a disk device 1 includes a disk 2 as a recording medium, a motor 3 for rotating and supporting the disk 2, a head 5 for writing and reading signals to and from the disk 2, a head driving mechanism 6, A motor drive circuit 4 for driving the motor 3 and a head drive circuit 7 connected to a head drive mechanism 6 are provided. Both drive circuits 4 and 7 are connected to a microprocessor 8.

The microprocessor 8 has two operation modes, a quick mode and a silent mode, and further has a built-in switch circuit 15 for switching between these two operation modes according to an instruction from a higher-level device (system). I have. The switch circuit 15 in the microprocessor 8 is equivalent to the switch circuits 9 to 12 shown in FIG. 1, and various operation modes are determined according to the setting state.

FIG. 3 is a schematic configuration diagram of a disk device according to a third embodiment of the present invention. In this embodiment, a case where a current limiting circuit 16 is built in a microprocessor 8 is shown.

In FIG. 3, a disk device 1 includes a disk 2 as a recording medium, a motor 3 for rotating and supporting the disk 2, a head 5 for writing and reading signals to and from the disk 2, a head drive mechanism 6, A motor drive circuit 4 for driving the motor 3 and a head drive circuit 7 connected to a head drive mechanism 6 are provided. Both drive circuits 4 and 7 are connected to a microprocessor 8.

In the microprocessor 8, two operation modes, a quick mode and a silent mode, are set, and further, a switch circuit 15 for switching these two operation modes by an instruction from a higher-level device (system);
A current limiting circuit 16 for individually determining the maximum current value flowing through both drive circuits 4 and 7 is built in.

The maximum current value determined by the current limiting circuit 16 is associated with the operation mode selected by the setting of the switch circuit 15. For example, when the quick mode is selected, the maximum current value is limited. No, the motor drive circuit 4 is 2 A, the head drive circuit 7 is 0.9 A (each value is determined by voltage and resistance), and when the silent mode is selected, the maximum current value is Circuit 4
Is determined to be 1.5 A, and the head drive circuit 7 is determined to be 0.6 A, for example.

FIG. 4 is a schematic configuration diagram of a disk drive according to a fourth embodiment of the present invention. In this embodiment, the case where current limiting circuits 17 and 18 are incorporated in each of the driving circuits 4 and 7 is shown. I have.

In FIG. 4, the disk device 1 includes a disk 2 as a recording medium, a motor 3 for rotating and supporting the disk 2, a head 5 for writing and reading signals to and from the disk 2, a head drive mechanism 6, A motor drive circuit 4 for driving the motor 3 and a head drive circuit 7 connected to a head drive mechanism 6 are provided. Both drive circuits 4 and 7 are connected to a microprocessor 8.

In the microprocessor 8, two operation modes, a quick mode and a silent mode, are set, and a switch circuit 15 for switching between these two operation modes by a command from a higher-level device (system) is built in. ing.

The maximum current value determined by the current limiting circuits 17 and 18 is associated with the operation mode selected by the setting of the switch circuit 15. For example, when the quick mode is selected, the maximum current value is determined. , The motor 3 and the head drive mechanism 6 are operated by the drive circuits 4 and 7 having no limitation. And the maximum current value is 1.5 A for the motor drive circuit 4 and 0.6 A for the head drive circuit 7 when the silent mode is selected. Is determined so that the motor 3 and the head driving mechanism 6 operate. Therefore, although two types of motor drive circuits and two head drive circuits are apparently set, the operation is equivalent to the drive circuit of FIG.

FIG. 5 shows a change in the rotation speed (FIG. 5A) and a change in the current value (FIG. 5B) at the time of starting the disk motor (until reaching the steady rotation speed) in the above embodiment. .

The solid line shows changes in the motor rotation speed v and the current value I over time in the quick mode, and corresponds to the quick mode in FIGS. The dashed line indicates the change in the motor rotation speed and the current value over time in the silent mode without the current limitation.
Corresponding to the silent mode. The broken lines indicate changes in the motor rotation speed and the current value over time in the current-limited silent mode, and correspond to the silent mode in FIGS. Although FIG. 5 shows the operation at the time of starting the motor, the operation is reversed when the motor is stopped.

FIG. 6 shows a change in the moving speed (FIG. 6A) and a change in the current value (FIG. 6B) when the head is moved in the above embodiment.

The solid line shows the change of the head moving speed v and the current value I with the lapse of time in the quick mode, and corresponds to the quick mode of FIGS. The alternate long and short dash line indicates that the acceleration / deceleration is the same as in the quick mode and the maximum speed is v ₁
1 shows changes in the head moving speed and the current value with the passage of time in the silent mode limited to FIG. The broken line shows the change in the moving speed and the current value with the lapse of time in the silent mode in which the current value during acceleration / deceleration is limited to I ₁ and −I ₁ without limiting the maximum speed. Corresponding.

In addition, a silent mode in which both the maximum speed and the current value during acceleration / deceleration are limited can be considered.

In the above-described embodiment, two types of operation modes, the quick mode and the silent mode, are used. However, a normal (standard) mode, a quick mode that can be accessed at a higher speed, a lower speed and a lower power consumption than the normal mode. It is also possible to configure so as to switch and select three or more operation modes of the power silent mode.

In the above embodiment, once the system starts up in a certain mode, the disk motor speed is constant unless the mode is changed midway, so that the operation of raising the motor rotation speed for each individual access becomes unnecessary. In addition, there is no delay in the read / write operation associated with the startup.

FIG. 7 is a flowchart for explaining the operation relationship between the disk device and the host device in the present invention.

First, the power of the host apparatus having the disk device is turned on (701), and the power of the disk device is turned on (702). Immediately after the power is turned on, the operation mode is set according to the information stored in the ROM, and a stable state is reached (703). Immediately after that, the operation mode information at the time of the previous termination stored on the disk surface is read. Load and store the information in RAM (7
04). Then, a stable operation state is reached in the operation mode based on the information stored in the RAM (705). At this time,
A normal mode in which an intermediate performance between the quick mode and the silent mode can be set in the ROM is set in advance.

When the operation mode of the disk device is to be changed (706), a list of operation modes stored in the ROM of the disk device is first loaded from the upper device by an operation of the user of the upper device. (707).
The loaded operation mode list is highlighted on the display of the host device, especially the operation mode set last time, and the user selects one operation mode (708). Accordingly, the operation mode information stored in the RAM is rewritten to the operation mode information selected by the user, and the operation mode is determined (709). When the operation mode is changed by the user as described above, it waits for the operation mode to be stable again.

Thereafter, file access from the higher-level device to the disk device is started in the set operation mode, and required data transfer is performed. When the termination processing of the host device is started (710), the information of the final operation mode stored in the RAM of the disk device is recorded in a specific location on the disk surface (711), and the information of the next host device is stored. Becomes the “previous operation mode” that is used when restarted. When all the above processes are completed, the power supplies of the host device and the disk device are turned off (712).

Next, as a fifth embodiment, an embodiment will be described in which the disk device of the present invention is applied to a computer in which a commercial AC power supply and a built-in battery power supply are shared, for example, a notebook personal computer (personal computer). .

In general, the notebook type personal computer 20 uses a built-in battery when used for portable use and a commercial 100 VAC when used in an office or the like as a power supply form. When a built-in battery is used for a portable device, the power consumption of the system directly affects the continuous use time, and it can be said that the longer the continuous use time is, the better the disk device with low power consumption is. On the other hand, when 100 VAC is used as a power supply, there is no need to pay special attention to power consumption unless a power failure occurs. Therefore, a disk device capable of writing / reading information at a higher speed when accessing a file is better. It can be said that the performance is good. Therefore, a notebook-type personal computer consumes little power when used as a portable computer, but a disk device that can access a file at high speed as needed can be said to be convenient.

However, the conventional disk device has only one of the performances or the one having an intermediate performance which cannot be said either. This is because it is technically difficult to simultaneously achieve low power consumption and high-speed file access.

Therefore, in the present embodiment, the disk device 1 having a plurality of operation modes of each of the above embodiments is replaced with a notebook type personal computer (personal computer).
When using a commercial AC power supply as the power supply for the personal computer and attached disk device, the quick access quick mode is automatically selected, and when using the built-in battery power supply, the low power consumption silent mode is automatically selected. To be selected. These operation modes can be switched at any time by an instruction from a higher-level device (notebook-type personal computer), so that good performance can always be provided for the higher-level device.

As a specific mode switching command method from the device (personal computer) described above, the user is not required to hit the keyboard to input a command each time by devising the following method.

That is, first, a means for measuring an external power supply voltage (not shown) is provided in the power receiving unit of the host device as a mechanism for detecting whether or not power is being supplied from an external power supply. Normally, a notebook type personal computer is provided with a diode or the like for preventing a backflow from a battery to a commercial power supply, and is automatically switched to an internal battery when the external commercial power supply is cut off. Therefore, if the sensing mechanism detects that power is not being received from an external power source, that is, that the built-in battery detects that the host device is being used, an operation mode (silent mode) for low power consumption is performed on the disk device. Mode). When the sensing mechanism senses that the higher-level device is receiving power from an external power supply, it instructs the disk device to operate in an operation mode (quick mode) for high-speed file access. I do. Putting a command from the host device to the disk device is, in other words, equivalent to the disk device sensing the state of the host device. As described above, the relationship between the usage mode of the notebook type personal computer and the operation mode of the disk device is as follows. Is related to automatically setting an operation mode for performing high-speed file access.

As the magnetic disk drive used in the present invention, a magnetic disk drive having a magnetic head having a negative pressure slider structure can be used. This magnetic head is in contact with the disk surface when the magnetic disk is stationary, but when the rotational speed of the disk exceeds a predetermined value, regardless of the rotational speed (in any of the above operation modes, ) A constant flying height is maintained.

In the above embodiments, the magnetic disk device has been described, but the present invention can be similarly applied to an optical disk device and a magneto-optical disk device.

[0058]

As described above in detail, according to the present invention, the seek speed of the head and the rotational speed of the disk recording medium can be switched in two or more stages with one disk device. An operation mode that meets the needs of the user, such as selecting a low-speed silent mode when requesting file access with low noise and low power consumption and data transfer, and selecting a quick mode when requesting high-speed file access or data transfer. Can be arbitrarily selected. Further, since the conventional standby mode (standby mode in which the rotation speed of the disk motor is lower than the rotation speed at the time of reading and writing between individual access reading and writing) is not adopted, the motor rotation speed is increased at the time of successive data access ( (Start-up) operation is not required, and an effect that a delay in the read / write operation accompanying the start-up does not occur can be obtained.

Further, if these operation modes are selectively switched from the host device, the user can easily select the required mode.

Further, when the present invention is applied to a personal computer such as a notebook type personal computer which shares a commercial power supply and a built-in battery power supply, when the commercial power supply is used, a quick mode of high-speed reading / writing and high-speed seek is selected. High performance data transfer / access, low-speed read / write and low-speed seek silent mode are selected when battery power is used, so that it can be operated continuously for a long time with low noise and low power consumption. Is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a disk device including a drive circuit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a disk device including a drive circuit that switches modes according to an instruction from a higher-level device according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a disk device including a drive circuit having a current limiting circuit in a microprocessor according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a disk device including a drive circuit having a current limiting circuit in each drive circuit according to the embodiment of the present invention.

FIG. 5 is a diagram showing a change in rotation speed and a change in current value when the motor is started.

FIG. 6 is a diagram illustrating a change in a head moving speed and a change in a current value.

FIG. 7 is a flowchart illustrating a related operation between the disk device and the host device according to the embodiment of this invention.

FIG. 8 is a configuration diagram of a disk device provided with a conventional drive circuit.

FIG. 9 is a schematic perspective view of a notebook personal computer to which the disk device of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disk device 2 Disk (medium) 3 Motor 4 Motor drive circuit 5 Head 6 Head drive mechanism 7 Head drive circuit 8 Microprocessor 9-12 Switch 13 Disk circuit part 14 Standby control means 15 Switch circuit 16-18 Current limiting circuit 20 Note Book type personal computer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsuhiro Tsuneda 2880 Kozu, Odawara-shi, Kanagawa F-term in the Storage Systems Division, Hitachi, Ltd. 5D068 AA02 BB01 CC01 EE13 GG01 5D088 MM10 5D109 KB23 KB40

Claims (2)

[Claims] 1. A motor for rotating a disk-shaped recording medium for recording information, a motor drive circuit for driving the motor, a head movable to a predetermined position on the recording medium, and a head for driving the head A disk drive comprising: a drive mechanism and a head drive circuit; and a microprocessor for controlling the motor drive circuit and the head drive circuit, wherein the head is controlled by a command from a host device that is accessible to the disk drive. When the first operation mode is selected, the head drive circuit supplies a first drive current to the head drive mechanism, and the second operation mode is selected. When the third drive mode is selected, the head drive circuit supplies a second drive current to the head drive mechanism. A head drive circuit supplies a third drive current to the head drive mechanism, and a disk drive when the second operation mode is selected based on a noise level of the disk drive when the first operation mode is selected. Noise level is smaller, and
A disk device wherein the noise level of the disk device when the third operation mode is selected is lower than the noise level of the disk device when the second operation mode is selected. 2. The disk device according to claim 1, wherein a rotation speed of the recording medium rotation motor is switched in accordance with each of the first, second, and third operation modes. apparatus.