Electricity: motive power systems – Positional servo systems – Pulse-width modulated power input to motor
Reexamination Certificate
2002-03-21
2003-05-27
Leykin, Rita (Department: 2837)
Electricity: motive power systems
Positional servo systems
Pulse-width modulated power input to motor
C318S254100, C318S132000, C318S434000
Reexamination Certificate
active
06570357
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disk drive apparatus for reproducing or recording from/on a rotating disk, and also to a motor usable at least in the disk drive apparatus.
2. Description of the Related Art
In recent years, a disk drive apparatus such as an optical disk drive apparatus (DVD, CD, and so on) and a magnetic disk drive apparatus (HDD, FDD, and so on) includes a motor that electronically alters current paths to windings by using plural transistors.
FIG. 40
shows such a prior art motor usable in the disk drive apparatus, the operation of which will be described concisely here.
A rotor
2011
has a field part formed by a permanent magnet. According to the rotation of the rotor
2011
, a position detecting block
2041
generates two pairs of three-phase voltage signals K
1
, K
2
, K
3
and K
4
, K
5
, K
6
. A first distributing block
2042
generates three-phase lower conduction control signals L
1
, L
2
and L
3
corresponding to the voltage signals K
1
, K
2
and K
3
, and controls the conduction of lower NPN-type power transistors
2021
,
2022
and
2023
. A second distributing block
2043
generates three-phase upper conduction control signals M
1
, M
2
and M
3
corresponding to the voltage signals K
4
, K
5
and K
6
, and controls the conduction of upper PNP-type power transistors
2025
,
2026
and
2027
. Consequently, three-phase drive voltages are supplied to three-phase windings
2012
,
2013
and
2014
.
There are various problems in the above-mentioned prior art.
In the prior art configuration, the emitter-collector voltages of the NPN-type power transistors
2021
,
2022
and
2023
and the PNP-type power transistors
2025
,
2026
and
2027
are controlled in analogue fashion, thereby supplying drive currents of necessary amplitude to the windings
2012
,
2013
and
2014
. Consequently, the residual voltage drop across the power transistor in activated period becomes large, and the product of this residual voltage drop and the conducted current of the power transistor causes a large power loss. Since the drive currents to the windings have been large, the sum power loss has been extremely large. As a result, the disk drive apparatus including the motor produces a large power consumption and thus has a very low power efficiency.
In order to reduce the manufacturing cost, it is effective to integrate transistors, resistors, and the like on a single chip as an IC. However, a power loss and a heat generation of the power transistors are too large to integrate power transistors with other transistors and resisters into an IC. Especially, since the drive currents to the windings are large, the IC is likely to confront with a thermal breakdown caused by the heat generation from those power transistors. If a radiating plate is provided to the IC in order to prevent such a thermal breakdown, then the cost and the size will be increased greatly.
In recent years, there is a strong demand for a disk drive apparatus to reduce its vibration and an acoustic noise of the rotating disk in order to carry out a higher density reproducing and/or recording from/on such disks. In the prior art configuration, when a power transistor is changed over abruptly, a spike voltage is generated in a winding, thereby pulsating the drive currents. Therefore, the generated force is pulsated and a large vibration of the disk occurs, thereby producing a large acoustic noise from the disk.
In optical disk drive apparatus such as DVD-ROM and CD-ROM and magnetic disk drive apparatus such as HDD and FDD, the vibration of the disk produces a jitter of the rotational speed of the disk so that a bit error rate of the signal reproduced from the disk would become worse. The acoustic noise of the disk will interfere and disturb enjoyment of an audio-visual movie reproduced from the disk, because the acoustic noise is an audible noise. Further, in a disk drive apparatus using a recordable disk, a recording and/or reproducing mechanism of the disk drive apparatus is strongly demanded to reduce its power consumption because the recordable disk is easily affected to degrade the recording characteristics by heat or high temperature due to high power consumption.
It has been strongly desired to develop a disk drive apparatus and/or a motor in which each of or all of these problems are solved.
It is therefore an object of the present invention to solve the above-mentioned problems, respectively or concurrently and provide a disk drive apparatus and/or a motor that has the configuration suitable for reducing the vibration, the acoustic noise, and the power consumption.
Briefly stated, the present invention comprises a head for at least one of reproducing an information signal from a disk and recording an information signal on a disk, processing means for at least one of processing an output signal from said head and outputting a reproduced information signal, and processing an input signal and outputting a recording signal into said head; a movable member, having a field part, for driving said disk; Q phase windings, Q being an integer of three or more; voltage supplying means, including first and second output terminals, for supplying a DC voltage; Q first power amplifying means, each one of said Q first power amplifying means including a first power transistor for forming a current path between the first output terminal side of said voltage supplying means and one of said Q-phase windings; Q second power amplifying means, each one of said Q second power amplifying means including a second power transistor for forming a current path between the second output terminal side of said voltage supplying means and one of said Q-phase windings; altering signal producing means for producing altering signals; commanding means for producing a command signal in response to a rotational speed of said disk; first distribution control means for determining active periods of said Q first power amplifying means in response to output signals of said altering signal producing means, each of said active periods being larger than the period of an electrical angle of 360/Q degrees; second distribution control means for determining active periods of said Q second power amplifying means in response to output signals of said altering signal producing means, each of said active periods being larger than the period of an electrical angle of 360/Q degrees; and switching operation means for producing a modified command signal which responds with said command signal of said commanding means and has a part varied in response to at least an output signal of said altering signal producing means, producing a current detected signal in response to a current to said Q-phase windings from said voltage supplying means, and causing at least one power transistor among Q of said first power transistors and Q of said second power transistors to perform high-frequency switching in response to said modified command signal and said current detected signal.
Another aspect of the present invention is a disk drive apparatus having a head and processing means for reproducing an information signal from a disk and/or recording an information signal on a disk, comprising; a movable member having a field part, voltage supplying means for supplying a DC voltage, plural-phase windings, plural power transistors for supplying plural-phase drive current signals to said plural-phase windings from said voltage supplying means, altering signal producing means for producing a signal in response to a rotation of said movable member, commanding means for producing a command signal in response to a rotational speed of said movable member, and switching operation means for causing at least one power transistor among said plural power transistors to perform high-frequency switching, wherein said switching operation means produces a modified command signal which responds with said command signal of the commanding means and has a part varied in response to at least an output signal of said altering signal producin
Akin Gump Strauss Hauer & Feld L.L.P.
Leykin Rita
Matsushita Electric - Industrial Co., Ltd.
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