JPH04205963A - Disk device - Google Patents

Abstract

PURPOSE:To reduce power consumption without detriment to access time by providing a standby control means for decreasing a rotating speed of a medium to a specified target number of revolutions under a standby mode without performing the write and read. CONSTITUTION:The write and read of information is performed by a head 10 on a medium 12 to be rotated by a motor 14. Then, the standby control means 16 is provided for the purpose of decreasing the rotating speed of the medium 12 to the target number of revolutions under the standby mode without performing the write and read. Then, at the time of the standby mode without performing the write and read on the disk device, simultaneously with the cutoff of a power source for a disk circuit part 18, the rotating speed of the medium 12 is dropped to be capable of maintaining the rotation. By this method, the power required for restarting up the disk device can be small, and the access time from the restart-up to the capability of transferring data is shortened, and the power consumption is reduced.

Description

[Detailed Description of the Invention] [Summary] This invention relates to disk devices, mainly magneto-optical disk devices, in which information is written to and/or read from a medium rotated by a motor using a co-head, and power consumption is reduced without impairing access time. The present invention is designed to provide a standby control means for reducing the rotational speed of the medium to a predetermined target rotational speed in a standby mode in which no writing or reading is performed.

Field of Industrial Application] The present invention relates to a disk device in which a head writes and/or reads information to a medium rotated by a motor, and mainly relates to a disk device that performs optical recording and reproduction such as a magneto-optical disk device. Regarding.

Portable devices such as notebook computers are currently equipped with magnetic disk drives as hard disks.
It is also desirable to install an optical disk device or magneto-optical disk device with a large recording capacity.

In such portable devices, it is important to reduce power consumption in order to ensure continuous use time. Since the power consumption of the disk device in the entire mobile device is relatively large, it is desired to use the disk device efficiently by reducing its power consumption.

[Prior Art] Conventionally, 3.5-inch magnetic disk drives have been used as hard disks in portable devices such as notebook computers. On the other hand, magneto-optical disk devices are also becoming smaller, and consideration is being given to installing them in portable devices to take advantage of their large storage capacity.

[Problems to be Solved by the Invention] However, when mounting a conventionally announced magneto-optical disk device in a portable device, there are the following problems.

First of all, mobile devices are usually powered by batteries or secondary batteries, and the average power consumption of the system is directly reflected in the continuous usage time of the mobile device, and naturally the longer the continuous usage time, the better the performance. It can be said. Currently, a considerable portion of the power consumption of portable devices such as personal computers and word processors is consumed by disk devices.

Therefore, when the disk device installed in a portable device is not in use, the user performs operations such as turning off the power to the disk device. This can significantly reduce the power consumption of the system, and in some cases can reduce power consumption by as much as one-third.

Furthermore, even in disk devices, although the power consumption of electronic circuit parts is relatively low, the power consumption of mechanical drive parts is large.

By the way, in a magneto-optical disk device, in a steady state, the storage medium is rotated at a rotation speed comparable to that of a magnetic disk device.

Also, after the power is turned on to the disk device, the rotational speed of the medium is set to the specified rotational speed in a steady state (target rotational speed, for example, 2400
+pm), and this rise time is much larger than the steady state access time.

Furthermore, the initial motor torque required to rotate a stationary storage medium is relatively large.

For this reason, in magnetic disk drives, the power consumption when the disk starts rotating is specified separately.

For this reason, the conventional operation of turning off the power to a disk device when not in use to reduce power consumption is
There are at least two problems:

The first problem is that when it becomes necessary to read or write data, it takes a long time until the power to the disk device is turned on again and the data can actually be read or written. Originally, the access time of a magneto-optical disk device is comparable to that of a magnetic disk device, and is much better than that of a floppy disk device. However, if you turn on the power each time you use the device, you will not be able to take advantage of the performance of the magneto-optical disk device.

The second problem is that power consumption is large when the disk device is turned on again, and if the disk device is accessed intermittently and frequently, it is not possible to keep the disk device in permanent operation. This means that it is more advantageous in terms of required power. Furthermore, when driven by battery power,
A situation may occur in which the battery becomes exhausted during use, and the power necessary to restart the disk device cannot be supplied.

The present invention has been made in view of these conventional problems, and it is an object of the present invention to provide a disk device that can reduce power consumption without impairing access time.

[Means to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

First, the present invention is directed to a disk device in which information is written to and/or read from a medium 14 rotated by a motor 12 using a gutter 10 .

The present invention is characterized in that such a disk device is equipped with a standby control means 16 that reduces the rotational speed of the medium 14 relative to the target rotational speed in a standby mode in which no writing or reading is performed.

Here, the standby control means 16 operates in a first standby mode in which the power supply to the disk circuit unit 18 such as the sense amplifier and the head control unit is cut off while the medium rotation speed is kept at a steady value, and in a first standby mode in which the power supply to the disk circuit unit 18 is cut off. It is equipped with a second standby mode in which the media is cut off and the medium rotational speed is maintained at a reduced rotational speed, and when no writing or reading is performed for a certain period of time, the mode is switched to the first standby mode, and further writing and reading are performed in the state of the first standby mode. is not performed for a certain period of time, the mode is switched to the second standby mode.

Further, in the second standby mode, when no writing or reading is performed for a certain period of time, the rotation speed may be sequentially switched to a lower rotation speed in multiple stages.

Furthermore, to maintain the low rotation speed in the standby mode, the approximately set low rotation speed may be maintained by repeatedly driving and stopping the motor 14.

The disk device of the present invention includes a head 10 and a medium 12 of an optical disk device, an optical compact disk device, etc.
Targets disk devices with a structure where there is no contact between the two.

Further, regarding the magnetic disk device, it is sufficient to provide a head-up means for maintaining the head in a non-contact state with respect to the medium even when the number of rotations of the medium is reduced in standby mode.

[Function] According to the disk device of the present invention having such a configuration, in the standby mode in which no writing or reading is performed to the disk device, the power to the disk circuit section can be turned off and the rotational speed of the medium can be maintained at the same time. As a result, the power required when restarting a disk device is small, and the access time from restart to data transfer becomes possible is shortened, while the power consumption of the disk device is significantly reduced. can be reduced to

This effect is obtained based on the following three principles.

First, if the rotation of the storage medium in a disk device is completely stopped, the starting torque required to restart it is large, but if you increase the rotation speed from a state where it is rotating at a certain speed to a steady state, , the required torque is low and therefore the required power consumption is also low. This principle is physically
This is because the coefficient of static friction is larger than the coefficient of dynamic friction. In other words, the torque needed to start a motor from a stopped state is consumed by static friction, whereas the torque used to speed up rotation from a rotating state even at very low speeds is consumed by dynamic friction. .

Second, less power is required to maintain low speed rotation than to rotate at high speed. Energy to maintain rotation is consumed by friction with the motor shaft and media. Since this friction coefficient ideally does not depend on the number of rotations, the energy consumed is approximately proportional to the number of rotations.

Thirdly, as a matter of course, the time it takes from rotating at a certain speed to reaching the specified rotation speed is longer.
shorter than the time since stopped.

Embodiment FIG. 2 is a block diagram showing an embodiment of the present invention, taking a magneto-optical disk device as an example.

In Fig. 82, 100 is a main body of a magneto-optical disk device, and the main body 100 is provided with a medium 12 that is rotated at a specified speed in a steady state by a motor 14, and the medium 12 is a rewritable magneto-optical disk. . Head 10 for media 12.

will be provided. The head 10 is provided with a structure for optically reading or writing the medium 12, and writes information on the medium 12 by irradiating it with a light beam, and reads information recorded on the medium 12 by irradiating it with a read beam. Note that during the write operation, erasing processing is performed using an erase beam prior to the write beam.

A disk circuit section 18 including a sense amplifier 24, a head control section 26, and an interface circuit 28 is provided in the apparatus main body 100, and the interface circuit 28 is an SC8I.
Data is exchanged with the host via the bus (small computer system interface bus).

Further, the device main body 100 is provided with a power supply control section 20 and a motor control section 22. This power supply control section 20 and motor control section 22 constitute the standby control section 16 in the present invention.

The power supply control unit 20 receives a circuit power supply signal (Ci+cit
pove r) and motor speed signal (Mo'ton-sp
eed) is supplied. Furthermore, a power-on signal (Power) is supplied from the host to the apparatus main body 100. In response to these three signals from the host, the standby control means 16 has four operating modes shown in FIG.

In FIG. 3, operation mode (2) is when the power-on signal is off, and naturally the circuit power signal and motor speed signal are not obtained, and the power is off in all blocks of the magneto-optical disk device.

Next, the operation mode ■ is when the power supply signal is on, the circuit power supply signal is off, and the motor speed signal becomes low speed (S low). At this time, the power supply of the interface circuit 28, sense amplifier 24, and head control section is off, and the motor 14 that drives the medium 12 is in a low-speed rotation state because it is in a standby state in which no write or read access is performed. This operation mode (2) is defined as standby mode 2 in the present invention.

Next, the operation mode ■ is a case in which the power supply signal is on, the circuit power supply signal is off, and the motor speed signal is normal (Notmal), and similarly to the operation mode ■ as the standby mode 2, the interface circuit 28, the sense amplifier 24, Although the head control unit 26 is powered off, the motor 14 that drives the medium 12 is rotating normally, that is, at a specified target rotation speed. This operation mode (2) is referred to as standby mode 1 in the present invention. In addition, in the operation modes ① and ②, electronic circuit parts unnecessary for controlling the rotation of the motor 14, namely, the interface circuit 28, the sense amplifier 24, and the head control unit 26 are removed.
Although the power is turned off, if the static RAM in the circuit has a low power consumption mode, this mode can be used to put it in a standby state.

Furthermore, operation mode ■ is when the power supply signal is on, the circuit power supply signal is on, and the motor speed signal is normal rotation.
In this state, power is supplied to all blocks of the magneto-optical disk device, and the medium 12 is rotated at a specified target rotational speed to enable access, which is the normal operation.

Regarding the operation modes ■ to ■ shown in FIG.
That is, the mode is switched to standby mode 1, and while the rotation of the medium 12 of the motor 14 remains in the normal operation, the power to the disk circuit section 18 that is unnecessary for controlling the rotation of the motor is turned off. In this standby mode 1, the power saving effect is not so great because the power is only saved for the electronic circuit part, but since the drive of the medium 12 by the motor 14 normally rotates, the access time from the host can be made almost the same as the normal operation in operation mode ■.

Furthermore, when there is no writing or reading from the host for a certain period of time in the standby mode 1 as the operating mode (2), the mode is switched to the standby mode 2 as the operating mode (2). In standby mode 2, the disk circuit section 1 which is not necessary for motor control
In addition to turning off the power at 8, the drive of the medium 12 by the motor 14 is reduced from normal rotation to low speed rotation. For example, in current magneto-optical disk drives, the normal rotation speed is 240
Since it is Qrpm, it is 120Qrp in standby mode 2.
Drop to m. Due to this reduction in rotational speed, for example, as shown in Figure 4, the power consumption that was 200mA at normal rotation of 240Orpm can be reduced to half to 100mA by lowering it to 120Orpm in standby mode 2, resulting in a significant reduction in power consumption. Become.

Next, the operation of the disk device of the present invention will be explained with reference to the processing flow diagram of FIG. 5.6.

First, in a system equipped with a disk device, even if the power of the system itself is turned on, the power of the disk device is not turned on until a file access to a file on the disk device is actually requested. That is, when the system power is turned on in step Sl (hereinafter "step" is omitted) in FIG. 5, a load program is loaded from the ROM in S2, and an application is executed in S3. During this time, the power to the disk device remains off, that is, it remains in the operating mode (2) of FIG.

Subsequently, when an actual file access is performed, the power to the disk device is immediately turned on in S4. That is, the operation mode (2) shown in FIG. 3 is carried out, the power to all blocks of the disk device is turned on, and the rotation of the medium 12 is started by starting the motor 14. At this time, since it takes time for the motor 14 to reach the specified number of revolutions, stable operation of the disk device is waited for in S5, and file access for writing or reading is executed in S6. The time required to access files at this time is slower than usual, but this only occurs when you start using the system, so it does not have a significant impact on system control.

When there is no access to the disk device for a certain period of time after the first file access is completed in S6,
In S7, the disk device is set to standby mode 1. This setting of standby mode 1 may be performed when it is predicted that no access will continue for a certain period of time.

In standby mode 1, as shown in operation mode (■) in FIG. 3, the power to the disk circuit section 18 that is unnecessary for motor control is turned off, but the medium 12 is maintained at steady rotation by the motor 14. , the response when accessed again is fast.

Furthermore, when the state of standby mode 1 continues for a certain period of time, the disk device is set to standby mode 2, as shown at 88.

In standby mode 2, in addition to turning off the power to the disk circuit unit 18, the rotational speed of the medium 12 by the motor 14 is switched from the specified speed to a low speed rotation, and the motor 1
4. Reduce power consumption.

FIG. 6 shows the operation when a file access is received after the standby mode 2 is set at 88 in FIG.

When the disk device receives a file access while in standby mode 2, it first returns to standby mode 1 in S9 and motor 1
4 returns the drive of the medium 12 to steady rotation.

FIG. 7 shows the change over time in the rotational speed of the motor 14 of the disk device after the power is turned on.
It takes 2.4 seconds to reach 0 rpm.

Here, the elapsed time Ts after starting the motor can be expressed by the following equation.

TS=-(J・θa)・In(l-θS/θa)/(T
- ■) Here, Ts... Elapsed time after startup J... Moment of inertia including the medium T... Starting torque constant ■... Starting current θa... No-load rotational speed (angular speed) θS ...actual (target) rotational speed According to this formula, the elapsed time when starting from 120Orpm in standby mode 2 to steady rotation 240Orpm is approximately 1
．． 1 second, which is much shorter than the 2.4 seconds required when the power is turned on.

Next, when steady rotation is obtained in standby mode 1, the power to the disk circuit section is turned on at step 810, and the process waits for the interface circuit 28 and the disk device to be ready at step S11.
Execute file access in step 4.

Note that when a file access is received in standby mode 1, the process starts from S10.

FIG. 8 is a characteristic diagram showing the current consumption of the motor 14 when the power is turned on for the same elapsed time as in FIG. 7, and a large current consumption is required when the rotation starts immediately after the power is turned on. On the other hand, in the present invention, the start of disk rotation by the motor 14 is, for example, 120 Orp in mode 2.
Since the process starts from m, the power consumption can be significantly reduced compared to the conventional case where the power is turned on every time a file is accessed, which requires a large current consumption when the power is turned on as shown in FIG.

In the above embodiment, the number of rotations of the motor 14 is controlled in two stages: steady rotation and low-speed rotation in standby mode 2, or the number of rotations of the motor 14 may be set in more stages to achieve fine-grained control. It may also be possible to perform detailed control. For example, if there is no file access for a certain period of time, the speed will be 240 Orpm, which is the same as in standby mode 2, as shown in Figure 4, and if there is no file access for a certain period of time in this state, the speed will be halved to 120 Orpm, and if there is no further file access, the speed will be 400 rpm, 24 Orpm, and 12 Orpm. The current consumption may be reduced by lowering the current consumption in stages.

Further, since the rotation speed of the motor 14 in the standby mode of the present invention does not require stability during normal rotation, the control of the motor 14 by the motor control section 22 can be simplified. For example, on/off control such as cutting off the power to the motor 14, allowing it to idle, and restarting the motor before it stops idling is effective for reducing power consumption.

Furthermore, although the above-described embodiment has been exemplified by a magneto-optical disk device, the present invention can also be applied to an optical disk device, an optical compact disk device, etc. in which the head and medium do not come into contact with each other. Furthermore, in magnetic disk drives, the head is kept floating above the magnetic disk during steady rotation, but by adding a head-up means that does not allow the head to come into contact with the disk surface even when the disk rotation drops from steady rotation, this technology can be improved. The invention can also be applied to magnetic disk devices.

[Effects of the Invention] As described above, according to the present invention, when writing or reading is not performed for a certain period of time, the motor rotation can be reduced to significantly reduce power consumption. Furthermore, when a file is accessed in standby mode, the access time is sufficiently shorter than when starting from a stopped state, and the decline in system performance can be kept to the necessary minimum. Furthermore, since the torque from standby mode to steady rotation is sufficiently smaller than that at startup, power consumption can be significantly reduced, making it suitable for portable devices using battery power.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention; Fig. 2 is a diagram of the configuration of an embodiment of the invention; Fig. 3 is an explanatory diagram of the operation mode of the present invention; Fig. 4 is an explanatory diagram of current consumption with respect to rotational speed of the disk device. ; Figures 5 and 6 are processing flow diagrams of the present invention; Figure 7 is a characteristic diagram of the time and rotational speed after power-on of the motor of the disk device; Figure 8 is a characteristic of elapsed time and current consumption after power-on. It is a diagram. [Description of symbols 10: Head 12: Medium 146 Motor 16 Standby control means (section) 18: Disk circuit section 20, power supply control section 22: Motor control section 24: Sense amplifier 26: Head control section 28: Interface circuit

Claims (6)

[Claims] (1) In a disk device in which a head (10) writes and/or reads information to a medium (14) rotated by a motor (12), the medium (14) is in a standby mode in which neither writing nor reading is performed.
1. A disk device comprising standby control means (16) for reducing the rotational speed of the disk drive (16) relative to a target rotational speed. (2) In the disk device according to claim 1, the standby control means (16) supplies power to a disk circuit section (18) such as a sense amplifier and a head control section, and rotates the medium at a reduced rotational speed. a first standby mode in which the number of
a second device that cuts off the power supply to the disk circuit unit (18) and maintains the medium rotational speed at a reduced rotational speed;
and a standby mode, switching to the first standby mode when no writing or reading is performed for a certain period of time, and further switching to the second standby mode when no writing or reading is performed for a certain period of time in the state of the first standby mode. A disk device featuring: (3) In the disk device according to claim 2, the second
In the standby mode, when no writing or reading is performed for a certain period of time, the disk device is characterized in that the rotation speed is sequentially switched to a lower rotation speed in multiple stages. (4) In the disk device according to claim 1, maintaining the low rotation speed in the standby mode involves repeatedly driving and stopping the motor (14) to maintain the approximately set low rotation speed. A disk device characterized by: (5) The disk device according to claim 1, wherein the disk device is an optical disk device, an optical disk device, or an optical compact disk device. (6) In the disk device according to claim 1, the disk device is a magnetic disk including head-up means for maintaining the head in a non-contact state with respect to the medium even when the number of rotations of the medium is decreased in the standby mode. A disk device characterized in that it is a device.