Faster spin-down operation in a disk drive by utilizing pulsed braking

Claim 2

A disk drive comprising: a spindle motor having a plurality of windings; a spindle motor driver including switching elements connected to the plurality of windings; means for storing spin-down instructions; means for initiating a spin-down command; a microprocessor responsive to the spin-down command to receive and execute the spin-down instructions, wherein the execution of the spin-down instructions causes the microprocessor to cyclically perform the following operations: (1) providing a brake signal for a first selected period of time (T1), (2) providing a coast signal for a second selected time period (T2), and (3) repeating (1) and (2); the spindle motor driver being responsive to the coast signal to control the switching elements to cause the spindle motor to coast and being responsive to the brake signal to control the switching elements to brake the spindle motor.

Claim 3

The disk drive of claim 1 wherein the spindle motor includes a rotor rotatable at a variable magnitude rotational velocity, and the disk drive further comprises: means for producing a speed-indicating signal representing the magnitude of the rotational velocity; and wherein the execution of the spin-down instructions causes the microprocessor to perform the operations of: reading the speed signal to determine whether the magnitude of the rotational velocity is within a range bounded by a selected upper rotational velocity (ω1) and a second selected lower rotational velocity (ω2); while the magnitude of the rotational velocity is determined to be in the range, cyclically executing the operations of: (1) providing the brake signal for T1, (2) providing the coast signal for T2, and (3) repeating (1) and (2).

Claim 4

The disk drive of claim 2 wherein the execution of the spin-down instructions causes the microprocessor to perform the operations of: within each cycle in which the magnitude of the rotational velocity is determined to be lower than ω2, executing the following subcycle operation: (1) providing the brake signal.

Claim 5

The disk drive of claim 2 wherein ω2 is selected to be a safe braking rotational velocity such that substantially no heat related breakdown of any portion of the spindle motor and the switching elements occurs when the spindle motor is repeatedly braked for T1 and coasted for T2 at velocities in the range, and continuously braked for time periods greater than T1 at velocities less than ω2.

Claim 6

The disk drive of claim 2 wherein the execution of the spin-down instructions causes the microprocessor to further perform the operation of: within each cycle in which the magnitude of the rotational velocity is determined to be higher than ω1, executing the following subcycle operation: (1) providing the coast signal.

Claim 7

The disk drive of claim 2 wherein ω1 is equal to a maximum rotational velocity of the spindle motor.

Claim 8

The disk drive of claim 1 wherein T1 and T2 are fixed.

Claim 9

The disk drive of claim 1 wherein T1 and T2 are variable.

Claim 10

The disk drive of claim 2 wherein means for producing the speed-indicating signal produces the speed-indicating signal when the spindle motor is coasting.

Claim 11

The disk drive of claim 2 wherein means for producing the speed-indicating signal includes: means for detecting back emf zero crossings in the windings.

Claim 12

The disk drive of claim 2 wherein the means for producing the speed-indicating signal further includes: means for determining one revolution of the spindle motor based on the number of back emf zero crossings; means for providing a fixed clock signal; means for counting a number of clock periods of the fixed clock signal in one revolution of the spindle motor; and means for storing the number of clock periods.

Claim 13

A disk drive comprising: a spindle motor having a plurality of windings and a rotor rotatable at a variable magnitude rotational velocity; a spindle motor driver including switching elements connected to the plurality of windings; means for producing a speed-indicating signal representing the magnitude of the rotational velocity; means for storing spin-down instructions; means for initiating a spin-down command; a microprocessor responsive to the spin-down command to receive and execute the spin-down instructions, wherein the execution of the spin-down instructions causes the microprocessor to perform the following cycle and sub-cycle operations of: cyclically reading the speed signal to determine whether the magnitude of the rotational velocity is within a range bounded by a selected upper rotational velocity (ω1) and a second selected lower rotational velocity (ω2); within each cycle in which the magnitude of the rotational velocity is determined to be in the range, cyclically executing the following subcycle operations of: (1) providing a brake signal for a first selected period of time (T1), (2) providing a coast signal for a second selected time period (T2), and (3) repeating (1) and (2); within each cycle in which the magnitude of the rotational velocity is determined to be lower than the range, executing the following subcycle operation: (1) providing the brake signal; and the spindle motor driver being responsive to the coast signal to control the switching elements to cause the spindle motor to coast and being responsive to the brake signal to control the switching elements to brake the spindle motor.

Claim 14

A disk drive comprising: a spindle motor having a plurality of windings and a rotor rotatable at a variable magnitude rotational velocity; a spindle motor driver including switching elements connected to the plurality of windings; means for producing a speed-indicating signal representing the magnitude of the rotational velocity; means for storing spin-down instructions; means for initiating a spin-down command; a microprocessor responsive to the spin-down command to receive and execute the spin-down instructions, wherein the execution of the spin-down instructions causes the microprocessor to perform the following cycle and sub-cycle operations of: cyclically reading the speed signal to determine whether the magnitude of the rotational velocity is within a range bounded by a selected upper rotational velocity (ω1) and a second selected lower rotational velocity (ω2); within each cycle in which the magnitude of the rotational velocity is determined to be in the range, cyclically executing the following subcycle operations of: (1) providing a brake signal for a first selected period of time (T1), (2) providing a coast signal for a second selected time period (T2), and (3) repeating (1) and (2); within each cycle in which the magnitude of the rotational velocity is determined to be lower than the range, executing the following subcycle operation: (1) providing the brake signal; and the spindle motor driver being responsive to the coast signal to control the switching elements to cause the spindle motor to coast and being responsive to the brake signal to control the switching elements to brake the spindle motor.

Claim 15

The disk drive of claim 12 wherein ω2 is selected to be a safe braking rotational velocity such that substantially no heat related breakdown of any portion of the spindle motor and the switching elements occurs when the spindle motor is repeatedly braked for T1 and coasted for T2 at velocities in the range, and continuously braked for time periods greater than T1 at velocities less than ω2.

Claim 16

The disk drive of claim 12 wherein the execution of the spin-down instructions causes the microprocessor to further perform the operation of: within each cycle in which the magnitude of the rotational velocity is determined to be higher than ω1, executing the following subcycle operation: (1) providing the coast signal.

Claim 17

The disk drive of claim 12 wherein ω1 is equal to a maximum rotational velocity of the spindle motor.

Claim 18

The disk drive of claim 12 wherein T1 and T2 are fixed.

Claim 19

The disk drive of claim 12 wherein T1 and T2 are variable.

Claim 20

The disk drive of claim 12 wherein means for producing the speed-indicating signal produces the speed-indicating signal when the spindle motor is coasting.

Claim 21

The disk drive of claim 12 wherein means for producing the speed-indicating signal includes: means for detecting back emf zero crossings in the windings.

Claim 22

The disk drive of claim 19 wherein the means for producing the speed-indicating signal further includes: means for determining one revolution of the spindle motor based on the number of back emf zero crossings; means for providing a fixed clock signal; means for counting a number of clock periods of the fixed clock signal in one revolution of the spindle motor; and means for storing the number of clock periods.

Claim 25

The method of claim 21 further comprising the step of: while the monitored rotational velocity of the spindle motor is greater than or equal to ω1, coasting the spindle motor.

Claim 26

The method of claim 21 further comprising the step of: if the monitored rotational velocity of the spindle motor is less than ω2, braking the spindle motor to reduce the rotational velocity of the spindle motor to zero.

Claim 27

The method of claim 21 wherein ω1 is equal to a maximum rotational velocity of the spindle motor.

Claim 28

The method of claim 21 wherein the monitoring step is performed during a coasting of the spindle motor.

Claim 29

The method of claim 21 wherein T1 and T2 are fixed.

Claim 30

The method of claim 21 wherein T1 and T2 are variable.

Claim 33

The method of claim 28 wherein the braking step is performed by a braking mechanism and the method further comprises the step of: selecting ω2 to be a safe braking rotational velocity such that substantially no heat related breakdown of any portion of the spindle motor and the breaking mechanism occurs when the spindle motor is repeatedly braked for T1 and coasted for T2 at velocities in the range, and continuously braked for time periods greater than T1 at rotational velocities less than ω2.

Claim 34

The method of claim 28 further comprising the step of: while the monitored rotational velocity of the spindle motor is greater than or equal to ω1, coasting the spindle motor.

Claim 35

The method of claim 28 further comprising the step of: if the monitored rotational velocity of the spindle motor is less than ω2, braking the spindle motor to reduce the rotational velocity of the spindle motor to zero.

Claim 36

The method of claim 28 wherein ω1 is equal to a maximum rotational velocity of the spindle motor.

Claim 37

The method of claim 28 wherein the monitoring step is performed during a coasting of the spindle motor.

Claim 38

The method of claim 28 wherein T1 and T2 are fixed.

Claim 39

The method of claim 28 wherein T1 and T2 are variable.