Disk drive apparatus and motor

Details Disk drive apparatus and motor Disk drive apparatus and motor

2001-11-08

2003-05-20

Leykin, Rita (Department: 2837)

Electricity: motive power systems

Switched reluctance motor commutation control

C318S599000, C318S434000

Reexamination Certificate

active

06566827

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a disk drive apparatus including a motor and a motor which is suitable to be used in a disk drive apparatus.
In recent years, a disk drive apparatus such as a hard disk drive apparatus (a HDD apparatus), an optical disk drive apparatus and a floppy disk drive apparatus includes a motor which alters current paths to windings by transistors so as to drive a disk. Conventionally, in this kind of motor, current paths to windings are altered by PNP-type bipolar power transistors and NPN-type bipolar power transistors.
FIG. 32
shows a conventional motor. The operation of the motor is briefly described below. A rotor
2011
has a field part formed by a permanent magnet. Three position detecting elements of a position detector
2041
detect the magnetic field of the field part of the rotor
2011
. In other words, the position detector
2041
generates two sets of three-phase voltage signals, Kp
1
, Kp
2
and Kp
3
, and Kp
4
, Kp
5
and Kp
6
, from the three-phase output signals of the three position detecting elements in response to the rotation of the rotor
2011
. A first distributor
2042
produces three-phase low-side activation control signals Lp
1
, Lp
2
and Lp
3
responding with the voltage signals Kp
1
, Kp
2
and Kp
3
. The first distributor
2042
supplies the low-side activation control signals Lp
1
, Lp
2
and Lp
3
to the bases of low-side NPN-type bipolar power transistors
2021
,
2022
and
2023
so as to control the activation of the NPN-type bipolar power transistors
2021
,
2022
and
2023
. A second distributor
2043
produces three-phase high-side activation control signals Mp
1
, Mp
2
and Mp
3
responding with the voltage signals Kp
4
, Kp
5
and Kp
6
. The second distributor
2043
supplies the high-side activation control signals Mp
1
, Mp
2
and Mp
3
to the bases of high-side PNP-type bipolar power transistors
2025
,
2026
and
2027
so as to control the activation of the PNP-type bipolar power transistors
2025
,
2026
and
2027
. As a result, the current paths to three-phase windings
2012
,
2013
and
2014
are controlled so as to be opened or closed.
In this conventional configuration, power losses of the power transistors are large, and the power efficiency of the motor is very low. The NPN-type bipolar power transistors
2021
,
2022
and
2023
and the PNP-type bipolar power transistors
2025
,
2026
and
2027
supply drive voltages to the windings
2012
,
2013
and
2014
by controlling the voltage drops across the emitters and the collectors of them in an analogue manner. A residual voltage in each power transistor is large, and a large power loss and a heat are generated by the product of the residual voltage and a drive current of each power transistor. As a result, the power efficiency of the motor is low, and the power consumption of the disk drive apparatus is large. In addition, the power loss and the heat of the disk drive apparatus raise a temperature of a disk, and bit errors occur frequently during recording and reproducing a signal on/from a disk.
U.S. Pat. No. 5,982,118 and U.S. Pat. No. 5,473,232 disclose motors wherein power transistors are subjected to PWM operation (PWM: Pulse Width Modulation) to reduce power consumption. However, the motor configurations in accordance with U.S. Pat. No. 5,982,118 and U.S. Pat. No. 5,473,232 cause a very large high-frequency switching noise owing to the PWM operation of the power transistors. This switching noise disturbs a reproduction signal from the head and significantly raises the bit error rate of the reproduction signal of the disk drive apparatus.
In a magnetic disk drive apparatus (such as a HDD apparatus), and an optical disk drive apparatus (such as a DVD apparatus), a high-frequency noise must be minimized to reproduce stably a signal from a high-density disk. However, when power transistors execute PWM operation, a very large high-frequency switching noise occurs. Hence, the reliability of the reproduction signal of the disk drive apparatus is significantly lowed by the high-frequency noise. It is thus difficult to allow power transistors to execute PWM operation in a disk drive apparatus.
It is therefore an object of the present invention to solve the above-mentioned problems respectively or concurrently and to provide a highly reliable disk drive apparatus, which has a low power consumption and a low noise, and a motor suitable to drive a disk or the like.
BRIEF SUMMARY OF THE INVENTION
A disk drive apparatus in accordance with the present invention comprises:
head means for reproducing a signal from a disk;
processing means for processing an output signal from said head means and outputting a processed signal;
a rotor, having a field part which generates field fluxes, for driving said disk;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means, including two output terminals, for supplying a DC voltage;
power supplying means having Q first power transistors and Q second power transistors, each of said Q first power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
position detecting means for producing a position signal which responds with the rotation of said rotor;
activation operation means for controlling active periods of said Q first power transistors and said Q second power transistors responding with an output signal of said position detecting means, each of said active periods being larger than the period of 360/Q electrical degrees;
commanding means for producing a command signal which responds with a rotational speed of said disk; and
switching operation means for causing at least one of said Q first power transistors and said Q second power transistors to perform high-frequency switching responding with said command signal; and that
said switching operation means includes:
current detecting means for producing a current detection signal which responds with or corresponds to a composed current to said Q-phase windings from said voltage supplying means, and
switching control means for producing a switching pulse signal which responds with said current detection signal and said command signal, and
said activation operation means produces at least a slew-rate switching signal which responds with said switching pulse signal at a control terminal side of at least one power transistor among said Q first power transistors and said Q second power transistors, said at least a slew-rate switching signal having a smoothed voltage slope in at least one of rising and falling slopes, and causes said at least one power transistor to follow said at least a slew-rate switching signal, thereby supplying a high-frequency switching drive voltage signal to one terminal of said Q-phase windings, said high-frequency switching drive voltage signal having smoothed voltage slopes and responding with said current detection signal and said command signal.
With this configuration, since at least one of the Q first power transistors and the Q second power transistors performs high-frequency switching operation, the power losses of the power transistors are very small. In other words, the heat generation of the power transistors is very low, and a disk drive apparatus with a low power consumption is realized. In addition, since each of the active periods of the power transistors is larger than the period of 360/Q degrees and the composed current to the Q-phase windings is controlled responding with the command signal, the fluctuation of the generated drive force is remarkably reduced. So the acoustic noise and the vibration of the disk are reduced remarkably. Furthermore, since at least one of the power transistors executes high-frequency switching operation responding with the switching pulse signal of the switching operation means, the slew-rate switching signal

Affiliated with

Also associated with

Rating

Disk drive apparatus and motor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Disk drive apparatus and motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disk drive apparatus and motor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3072968