Method of and apparatus for reducing power consumption by computer disc drives

The subject of the invention is a method and device for reducing the power consumption of a computer optical disk drive in which the rotational speed is regulated, in particular for reducing the power consumption of a disk drive with a constant linear speed, with multiple speeds.

It is known that reducing the power consumption of computers and peripherals helps to save energy, and also allows reducing the dimensions of the power supply used. The smaller power supply is particularly beneficial in portable computers, such as laptops and notebooks.

It is known from US Patent No. 4,783,706 to reduce the voltage supplied to the computer head lifter when no recording medium is inserted into the disk drive. However, when the recording medium is in the disk drive, then this method can not save any power.

It is known from US Patent No. 5,197,055 a spinning system with retention of the recording medium when the disk drive has been inactive for a certain period of time, which results in saving power. However, there is a significant delay when it is necessary to increase the disk revolutions to achieve operational speed.

It is known from the US Patent No. 4,987,502 a system of free selection of subsequent disk paths, used to reduce the power consumption of the head. The system counts inactive periods to determine when to move the head. When the specified maximum number of inactive periods is reached, the system uses the driver to stop the spinning disk. Stopping a spinning disk has the same effect on power consumption as the stop spinning method described in U.S. Patent No. 5,197,055, and there is also a significant delay in achieving operating speed after stopping.

Similar methods and devices for moving the head to reduce power consumption are also known in U.S. Patent Nos. 5,050,015 and 5,117,155. U.S. Patent No. 5,050,015 describes a system for moving the head to a resting path or area outside the usable area magnetic paths. The position of the path and the waiting time depend on which paths are read most often because the goal is to reduce power consumption. The control system is stopped and started to obtain displacement. Unfavorably stopping and starting the electronic control system results in higher power consumption. U.S. Patent No. 5,117,315 describes a head displacement system when the processor detects the presence or absence of disk rotation. The system is able to reduce power consumption by slightly displacing the head by two or three paths and by raising the head when the disk is started. Power is saved by reducing the resistance of the head inadvertently contacting the disk at boot, but the device and method are not useful for saving power when the disk is already in motion.

The method and apparatus for moving the head to a safe original position by controlling the microprocessor when it is sensed that power supply to a rotating disk is to be interrupted is known from US Patent No. 4,658,308. Slight power savings are likely to be obtained by reducing any adverse resistance that would occur if the head interfered with disk rotation. However, the method and device are ineffective to reduce power consumption when the disk spins during proper operation.

The abbreviations for Japanese descriptions, presented in volume 15, No. 220, / P-1211 /, June 5, 1991, show how to reduce the power consumption of a computer's stationary magnetic disk. It determines whether there was no disk access in the set time. If there was no access, the magnetic head moves to the external path of the magnetic disk and, using an additional speed control system, reduces the rotational speed of the disk with the minimum required number of turns.

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European Patent Application No. 0 364 222 describes a method in which the number of revolutions of the hard disk is reduced so that the disk stops rotating after a certain time.

The method according to the invention consists in determining whether the disk drive is inactive and a search signal is sent to the head actuating system, whereby the head is moved to the disk carrier path closest to the external circuit of the disk carrier, if the disk drive is inactive, thereby reducing angular velocity of the disk to maintain the linear speed of the disk carrier relative to the head at the lowest level, at which data is still being read or data is being written to disk with a head.

Preferably, if the disk drive is inactive, the head moves to the outer periphery of the disk medium, then a search signal is sent to the head actuating system, thereby moving the head from the outer periphery path to the path corresponding to the location of the data in response to the data read order.

Preferably, if the disk drive is inactive, the head moves to the external circuit of the disk carrier, then the angular speed decreases until the rotary motor stops rotating if the disk drive remains inactive for a specified period of time.

Preferably, if the disk drive is inactive for a specified period of time, the angular speed decreases until the rotary motor stops rotating, then the angular speed of the rotary motor increases and a search signal is sent to the head actuating system, thereby moving the head from the external circuit path to the path corresponding to the location of the data in response to the data read order.

In the device according to the invention, a microprocessor equipped with a memory with a microprocessor is provided between the spindle control module and the clock for supplying the search signal to the head actuator for moving the head to the disk path closest to the disk outer circuit if the disk drive is inactive.

An advantage of the invention is to reduce the power consumption of the optical disk device without significantly reducing the response time to the data search order. Another advantage of the invention is to provide a method and device for reducing power consumption that does not require removing the disk from the optical disk device. The power consumption is reduced in the optical disk device by determining when an inactive period occurs, and then issuing an order to reduce the speed of the rotary motor that drives the disk medium to the lowest operating level or directly below the operating level, without completely stopping or reducing disk rotation during the period inactive state. The operational level refers to the angular velocity at which the head can still read and write data.

When using a CLV disk drive with a constant linear speed, a signal is sent from the microprocessor to the actuator to cause the readhead to search for an external path. when there is a specified period of inactive status. This is advantageous because the angular velocity of the disc carrier is lower at the outer circumference for a given constant linear speed, i.e. the speed measured under the head, and therefore the power consumption of the rotary motor that drives the disk is lower.

The advantage is that the disk is operational because it never reduces revolutions completely to the point where it stops spinning, except for disks left inactive for long periods of time. There is therefore no significant delay associated with increasing disk revolutions after receiving the command. The invention can therefore be used to reduce the power consumption of a rotary disk engine while keeping the disk in operational condition. Given the exception mentioned, if the disk is left inactive for a certain period of time, which is quite long, disk spin may be stopped. The disc according to the invention will only stop or after a motion case

177 399 head to the external path for CLV drives or reduce the angular speed to the lowest selected speed for multi-speed CLV drives.

The subject of the invention is shown in the embodiments in the drawing, in which Fig. 1 shows a block diagram of the device for reducing the power consumption of a computer optical disk drive drive, Fig. 2 - disk carrier for disk drives with linear speed trap, Fig. 3 - angular speed graph as a function of disk radius, Fig. 4 is a flowchart in one embodiment of the invention and Fig. 5 is a schematic timeline showing the order of operations according to the invention.

The invention is based on the principles of electrical engineering associated with disk drives, and in particular DC motors for rotating disk carriers.

Ohm's law determines the motor voltage V = I · R, and the motor power is determined by the relationship: P = V · I = V²/ R. The motor voltage is related to its angular velocity by the equation: V = Ke · ω, where Ke is the voltage steel depending on the motor characteristics, and ω is the angular velocity of the motor. As a result, engine power is determined by the relationship:

P = (Ke2 · <»2) / R.

Due to the fact that the power consumed by the malehe motor when the angular speed of the motor decreases, it is desirable to use this compound in the method and apparatus of the invention.

Figure 1 is a block diagram of an apparatus for reducing the power consumption of a disk drive 10, preferably an optical disk drive, also of non-optical disk devices, such as direct access storage devices. The invention is useful in disk devices using CLV steel linear speed control systems. The microprocessor 12 has its own memory, e.g., direct access memory 13 and permanent memory 15, which is used to remember orders and perform tasks, e.g. power-on tests. This memory is used to remember microprocessor 14, which is a set of pre-programmed instructions to perform microprocessor functions, preferably in microprocessor 14 of microprocessor 12, which is part of the disk drive 10. Instructions can also be executed by other means, including an application program written, for example, in the universal programming language C and operating in the control system 26, which connects to the disk drive interface 10 through the connecting systems 27. It is more effective to execute instructions 27. More effective is to execute instructions directly on the microprocessor because the length of the instruction data path is kept to a minimum. The instruction set depends on the microprocessor, for example as described in Intel, Microprocessor Peripheral Handbook, volume 1 and J. Crawford and P. Gelsinger, Programming the 80386.

In Figures 1 and 2, the microprocessor 12 communicates with the control system 26, which is, for example, a personal computer microprocessor, through connecting circuits 27, which are, for example, an interface card for small SCSI computer systems. The microprocessor 12 controls the spindle control module 16, which controls the rotary motor 18 receiving power from the power supply 19. The rotary motor 18 has a rotary element 24 and a disc 22 for disks, receiving and rotating disk carrier, such as disk 30 of Fig. 2. The microprocessor 12 also controls the actuation system 17, which by means of a known mechanism controls the movement of the data reading head 23. Data read from the head are passed through buffer 28 and data systems 25 to control system 26. Spindle control module 16 and actuation system 17 are controlled by microprocessor 14 on microprocessor 15 according to whether the device is programmed for systems with constant linear speed or at constant angular velocity. The microprocessor 12, containing the microprocessor 14 and containing the individual RAM 13 and ROM 15 and the clock 11, form the power reduction module 21 for the disk drive 10.

One embodiment of the invention is applicable to known disk drives with constant linear speed. In the li6 optical disk drive

177 399 medium, such as CR-ROM, or read-only compact disk, a laser head is used as the speed transducer.

Figure 2 shows a CD-ROM 30 using a single path 32 forming approximately concentric circles, such as circles 33 and 34. The single path spirals away from the center 35 of the disk 30 to the outer circuit 36. The sector 37 containing data has the same logical and physical dimensions like all other sectors on the disk. Although only one path actually exists, each approximately concentric circle is discussed as a path. The imaginary radius line r is shown as running from the center 35 to the outer circumference 36. Points r, ir₀ on the radius line r correspond to an inner radius starting near the center of the disk and an outer radius measured near or at the outer circumference. The angular velocity of every disk is equal to the angular velocity of the rotary motor that rotates it. Paths 33a and 34a correspond to circles 33 and 34. Thus, path 33a is the path closest to the outer circumference of disk 30.

Figures 3 and 4 explain the critical relationship between the disk radius and the power consumed by the motor using a disk drive with a constant linear speed where the disk drive 10 constantly changes the speed at which the disk 30 rotates, so that when the data read head 23 moves through part disk, the speed measured at the head is kept constant. This speed is indeed the speed of the media read by the head and can also be changed in devices with multiple speeds. However, after selecting the speed, it is kept constant when the angular velocity changes. The dynamic kinematic or rotational relationship is determined by the equation: = r · ω, where r is the disk radius, is a constant tangential linear velocity, i.e. with a direction perpendicular to both the perpendicular axis of rotation and the radius, data measured at the head, which is angular velocity usually measured in revolutions per minute. For a given linear VD speed_these, the appropriate angular velocity must decrease in order to realize the given relationship as the radius increases from the center of the disk to the outer circumference of the disk.

Figure 3 is a graph showing angular velocity ω as a function of disk radius in a multi-speed drive, using a constant linear speed system for illustration. Points r, and ro correspond to the radius line r in Fig. 2. The upper curve 38a of Fig. 3 shows the decrease in angular velocity which, together with the increasing radius at higher speeds of the CLV drive with multiple speeds. The lower curve 38b shows a similar relationship, but at lower speeds of the CLV drive with many speeds. This relationship determines the power consumption: P = (Ke² · <O2) / R and further.

P _Kd² · Ν ^ r²R

The invention uses this principle to reduce power consumption in a disk drive, namely an automatic method and device using the fact that the increase in radius r to its maximum value causes a reduction in angular speed, and therefore the power consumption of a rotary motor in a disk drive with a constant linear speed, leaving the drive disk in operational state. The operational level or speed is the disk speed at which the head reads or writes data to the disk.

Figures 1 and 4 explain a preferred embodiment of the invention. Fig. 4 shows an overview of the instructions included in the flowchart. At each step, microprocessor 12 executes the instructions of the microprocessor to perform the process, however, for simplicity, only the microprocessor will be included. The start step 41 of microprocessor 12 is consistent with turning on the disk drive power. The active drive check step 42 is performed by the microprocessor 12 to determine if any data is being transferred between the head 23 and the disk or between the buffer 28 and the data systems 25. Alternatively, step 42 is performed by the control system 26 to determine if any files are currently open, it is being read or has been entered. If this happens, at 177 399 the momentum is considered active and the clock 11 used to measure the periods of inactive state is reset to zero in step 43. Step 42 is carried out continuously until all activity disappears, and when this condition is met, the drive is considered inactive. The processor then checks the clock 11 to determine if the specified time T "has elapsed while the drive remains inactive in step 44. During this time, the drive is still being checked for active status. After a specified time, with an inactive drive, you can then determine that the active level of the drive is below the specified active reference level. Thus, after the time t, measured in the clock 11, exceeds the specified time T "while the drive is in the inactive state, the microprocessor 12 sets the disk drive 10 to the power saving state in step 45. It is also possible to cause a power saving condition if the measured time t is less than the specified time T ,.

In the constant speed disk drive of Figures 1, 2, 3 and 4, a message is sent from the microprocessor 12 to the actuation system 17 to cause the head 23 to search for path 33a that has the maximum radius measured from the center of the disk in step 45 of Fig. 4. The spindle control module 16, with an automatic design suitable for maintaining a constant linear speed, compensates by reducing the angular speed of the rotary motor 18 to the lowest operating level in Fig. 3, where the horizontal coordinate is at point r₀as shown in step 45. Given the compound previously described which causes a reduction in power as the radius is increased and the angular velocity is reduced, the power savings are significant. The advantage is particularly significant because the power is inversely proportional to the square of the ray. Additional power savings are sensed by the microprocessor 12, which then issues an command to the spindle control module 16 to select the lowest achievable multi-speed drive speed in step 46. For a CLV drive at low speed, which occurs when the head is on an external path, for example path 33a, only a simple search order issued by the microprocessor 12 is required to access data located anywhere on the disk. Although the change in speed is associated with the search for a CLV drive, this change is associated with each search performed on the CLV drive. Therefore, the drive is still fully operational in a power saving state. It is advantageous that the disk rotates at a reduced speed when it is inactive, instead of reducing idle speed because it takes a significant amount of time to reach operating speed.

Figure 5 shows a timeline 70 where time is measured in the direction of 76 and shows that the total reduction of the rotation of the device can be added to the general method of reducing power consumption described above if the device was in a state of power reduction for a given period of time. Tom places, for example, when a computer that uses a disk drive remains turned on but is unattended. The device is referred to as the active device, as shown in segment 72 of the time line. The active device is determined as described above in step 42 of Fig. 4. A device or drive that is inactive in segment 74 for T seconds in segment 77 is switched to a state of power reduction in segment 78 in which it remains by T_LOW seconds in segment 82, and then the engine speed is reduced until the engine stops rotating in segment 83. This way, the device and the device for reducing power consumption in normal operating condition are combined with the technique of additional reduction of power consumption for drives left inactive for a long time period of time. Such a method in the preferred embodiment is carried out by the microprocessor 12 by means of the instructions in microprogram 14. The control system 26 is also programmed to implement this method. If necessary, the device can rotate back to operating speed.

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FIG. 2

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