JPH0429549A - Magnetic disc drive motor - Google Patents

Abstract

PURPOSE:To perform rotational speed control and phase control of a spindle motor accurately even upon fault of a Hall IC by providing position identifiers, corresponding to several types of coil conduction patterns required for rotation of a motor, concentrically to a stator shaft at the outside of a rotor while corresponding to the position of magnet. CONSTITUTION:An output corresponding to a pattern on a plate 21, read out through a position sensor 61, is provided to a motor position detecting circuit 63 and an index detecting circuit 65. The motor position detecting circuit 63 detects the rotational position of a rotor and provides a detection signal to a conduction phase switching circuit 64. The conduction phase switching circuit 64 selects a coil 75 to be conducted based on a rotor position and a switching signal is provided to a spindle motor rotation control section 68. The spindle motor rotation control section 68 produces a driving signal for the coil 75 based on a coil phase switching signal fed from the conduction phase switching circuit 64 and an error signal fed from a speed control section 67 thus driving a spindle motor 20 accurately.

Description

[Detailed Description of the Invention] [Summary] Regarding the disk drive motor of a magnetic disk device, even when a position sensor for controlling the rotational speed and phase of the motor provided inside the rotor fails, it can be fixed by other means. The aim is to provide a magnetic disk drive motor that can control the rotational speed and phase of the motor.The motor is equipped with multiple stator coils installed on the outer circumferential surface of a fixed shaft fixed to the housing, and a bearing. A rotor that is rotatably supported by a fixed shaft through a rotor, has a magnetic disk on its outer periphery, and a plurality of permanent magnets that face a coil on its inner periphery, and a support member inside the rotor that faces the permanent magnets. In a magnetic disk drive motor equipped with a plurality of position sensors provided so as to control the power supply, and a motor control section that controls energization of the plurality of coils based on the output signals of the position sensors, the motor is provided outside the rotor. Position identifiers corresponding to several types of coil energization patterns required for motor rotation are provided concentrically with the fixed shaft and corresponding to the positions of the magnets.

[Industrial application field]

The present invention relates to a magnetic disk drive rotor, and more particularly to a magnetic disk motor that can perform rotational speed control and phase control even when a position sensor provided inside the rotor fails.

In recent years, magnetic disk drives have been required to be smaller and more sophisticated as external storage devices for computers, word processors, etc., and the spindle motors that rotate the magnetic disks within the devices are also required to have high rotation accuracy. has been done. For this reason, conventionally, a position detector such as a Hall element is provided inside the rotor to detect the rotational position of the rotor, and this position detector outputs the phase switching timing and energization pattern to control the rotation of the motor. has been done. However, since this position detector is provided inside the rotor, there is a problem that if it breaks down, the motor cannot be rotated normally, and it is desired to rescue user data in such a case.

[Conventional technology]

FIG. 7(a) shows the configuration of a conventional magnetic disk drive 80 incorporating a three-phase type brushless spindle motor 70. In the figure, reference numeral 79 denotes a housing of the magnetic disk device 80, and a fixed shaft 71 of the spindle motor 70 is fixed to this housing 79. A cylindrical rotor 73 is attached to the fixed shaft 71 via two bearings 72, and the rotor 73 can rotate around the fixed shaft 71. and,
A plurality of magnetic disks 74 are fixed to the outer peripheral surface of the rotor 73.

On the other hand, a plurality of magnets 76 are attached to the inner peripheral surface of the rotor 73, and a plurality of coils 75 are provided to the outer peripheral surface of the fixed shaft 71 in correspondence to the number of magnets 76. Further, a support disk 77 is fixed to the outer circumference of the fixed shaft 71 inside the rotor 73, and a plurality of Hall elements or holes are mounted on the support disk 77 so as to face the magnet 76. IC78 is provided. The Hall element or Hall IC 7B detects leakage magnetic flux of the magnet 76. The power line 75D to the coil 75 and the signal line 78S from the hole C78 are
It was drawn out of the housing 79 through a thin hole provided in the fixed shaft 71.

FIG. 7(g)) is a view of the magnet 76 shown in FIG. 7(a) viewed from the bottom side, and in this example, the magnet 76 is a four-pole permanent magnet. FIG. 7(C) shows when the magnet 76 has four poles,
It shows the position of the Hall IC 78 mounted on the support disk 77. In this example, the Hall IC is 78A
, 78B, and 78C, and they are arranged at 60° intervals.

Figure 80)) shows the magnet 76 shown in Figure 7(a) and the hole ICs 78A, 78B, 78 when the Hall ICs 78A, 78B, 78C are as shown in Figure 8(a).
This shows the output signal of C. When the magnet 76 has four poles, the leakage magnetic flux of the magnet 76 when the rotor 73 rotates once is:
Hole I C78A, 78B, 78C shown in Figure 8 (a)
), it is detected as a Hall signal that inverts every 180 degrees of electrical angle. Also, conventionally, Hall IC78C
A signal is created by dividing the Hall signal from 2 by 2, and from the rise of this signal, a rotational speed index pulse of 1 pulse/round is created, and the rotational speed of the magnetic disk is obtained from this index pulse.

A phase switching signal for the coil 75 of the spindle motor 70 was obtained by Hall signals from the three Hall ICs 78A, 78B, and 78C.

[Problems to be Solved by the Invention] However, in the spindle motor 70 of the magnetic disk 80 configured as described above, the Hall ICs 78A, 7
If either 8B or 78C breaks down, it is not possible to disassemble the spindle motor 70 and replace the IC, so open the cover of the disk drive 80 and mechanically connect the other motor from the outside. Conventionally, data in the disk drive 80 was rescued by rotating the spindle motor 70, but this rescue method had the following problems.

()) Due to distortion of the housing 79 due to mechanical connection of another motor from the outside, the fixed shaft 71 is distorted, causing misalignment between the head and the disk, resulting in data loss.

(2) Since the casing 79 is opened and the motor from the outside is mechanically connected, dust may be generated, or if external dust enters the casing 79, this dust may be caught between the head and the disk. High risk of head crash
Reliability is compromised.

(3) Spindle motor 7 is driven by another motor from outside.
Although the rotation speed at 0 can be controlled, due to the disappearance of the Hall signal from the Hall IC, the rotational position of the motor cannot be controlled, so the data cannot be read accurately.

The present invention solves the problems that occur when the Hall IC fails in the conventional magnetic disk drive motor, and without increasing the cost of each individual magnetic disk drive, in an outer ring rotating spindle motor (in-hub motor).
It is an object of the present invention to provide a magnetic disk drive motor that can accurately control the rotational speed and phase of a spindle motor even when a Hall IC fails.

[Means to solve the problem]

The structure of a magnetic disk drive motor of the present invention that achieves the above object is shown in FIG. As shown in the figure, the present invention includes a plurality of stator coils 5 provided on the outer peripheral surface of a fixed shaft l fixed to a housing 9, rotatably supported by the fixed shaft 1 via bearings 2, A plurality of permanent magnets 6 facing the magnetic disk 4 and the coil 5 are located on the inner circumference.
and a support member 7 inside the rotor 3.
a plurality of position sensors 8 provided to face the permanent magnet 6 via the motor control section 10 that controls energization of the plurality of coils 5 based on output signals of the position sensors 8;
In a magnetic disk drive motor equipped with a magnetic disk drive motor, a coil 11i! is installed outside the rotor 3 corresponding to several types of coil energization patterns necessary for motor rotation. This device is characterized in that the li besegment 11 is provided concentrically with the fixed shaft 1 and in correspondence with the position of the magnet 5.

[Effect]

According to the magnetic disk drive motor of the present invention, a Hall IC built in the rotor of an outer ring rotating type spindle motor
If any one of them fails, the rotational position of the motor can be detected from outside the rotor by bringing a position sensor close to a position detector provided outside the rotor.

Therefore, even when the Hall IC fails, the rotational speed control and phase control of the spindle motor can be accurately performed based on this motor rotational position signal. As a result, even when the Hall IC fails, the rotation of the magnetic disk drive motor can be controlled correctly, making it possible to rescue data in the disk device.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view showing the structure of an embodiment of the magnetic disk drive motor 20 of the present invention built into the magnetic disk drive 30, and the same reference numerals are given to the same components as in the prior art. The housing 79 of the magnetic disk device 30 includes
A fixed shaft 71 made of magnetic material of a three-phase spindle motor 20 is fixed. This fixed shaft 71
A cylindrical rotor 73 attached through two bearings 72 can rotate around a fixed shaft 71. A plurality of magnetic disks 74 are fixed to the outer peripheral surface of the rotor 73.

Further, a plurality of magnets 76 are attached to the inner peripheral surface of the rotor 73, and the magnets 76 are attached to the outer peripheral surface of the fixed shaft 71.
A plurality of coils 75 are provided corresponding to the number of coils 75. A support disk 77 is fixed to the outer circumference of the fixed shaft 71 inside the rotor 73, and a plurality of Hall ICs 7 are mounted on the support disk 77 so as to face the magnet 76.
B is provided. Hall ■C78 detects the leakage magnetic flux of the magnet 76, and connects the power line 75D to the coil 75 and the signal line from the Hall IC 78? The BS is drawn out of the housing 79 through a thin hole in the fixed shaft 71. The spindle motor 20 of this embodiment is also a four-pole motor, and the positional relationship between the magnet 76 and the Hall ICs 78A, 78B, and 78C is shown in FIG. 7(a).

This is the same as the conventional example explained in FIG. 8(b) and FIG. 8(a).

Magnetic disk drive motor 20 configured as above
In this embodiment, a ring-shaped plate 21 containing phase switching information is attached to the bottom surface of the rotor 73 as a position detector. Further, a through hole 31 is provided in a part of the housing 79 facing the rotation locus of the plate 21, and this through hole 31 is usually closed with a cover 32 made of rubber or the like to prevent dust from entering. has been done. This through hole 31 is for inserting a position sensor, which will be described later, when any of the holes TC 78A, 78B, and 78C fails, and the position of this through hole 31 is determined in advance.

FIG. 3 shows an example of phase switching information to be included in the plate 21 of FIG. 2, and the plate 21 of this embodiment includes:
The phase switching information is written in six levels of shading according to the position of the magnet 26 using a shading pattern at equal intervals. The plate 21 shown in FIG. 3 is divided into 12 equal blocks with respect to its center point, and the same shading pattern is written point-symmetrically on the right and left halves of the plate 21. Note that since this shading pattern can be formed by printing, the color density and position can be formed accurately.

FIG. 4 shows the positions of the shading patterns on the plate 21 configured as shown in FIG. 3, and the EMF (eIctro m
tive force: Back electromotive force, Ea, Eb, E
c) and the outputs Ha, Hb, and Hc of the Hall ICs 78A, 78B, and 78C. As shown in this figure, if the six levels of shading of the plate 21 are set to become darker every 60° for an electrical angle of 0 to 360°, the outputs Ha of the Hall ICs 78A, 78B, and 78C
, Hb, and Hc can be made to correspond to the position of the plate 21.

If the phase switching information is a shading pattern, a single analog detector that recognizes shading may be used as a position sensor. For example, a phototransistor is used as the analog detector, and reads reflected light from an adjacent LED light plate.

The read signal is converted into six analog voltage levels from level 1 to level 6, and is repeatedly output every 360 degrees of electrical angle. Note that the index pulse for detecting the rotational speed of the disk may be generated at the point of change in the analog output.

In addition, in the above-described embodiment, a six-level pattern of shading was formed on the plate 21, but the positional information of the magnet 26 included in the plate 21 is not limited to shading. FIG. 5 shows another embodiment of the position information of the magnet 26 included in the plate 21.
1 has six steps. In this case, a distance sensor may be used as the position detector. Furthermore, it is also conceivable that the plate 21 be formed of a magnetic recording medium so that the magnetically recorded identification information can be read by a head such as an MR element.

Next, in the embodiment configured as above, the hole I
A rescue method when any one of C78A, 78B, and 78C fails and the rotation of the spindle motor 20 becomes uncontrollable will be explained with reference to FIG.

If any of the holes 1c 78A, 78B, and 78C is broken and the rotation of the spindle motor 20 becomes uncontrollable, remove the lid 32 blocking the through hole 31,
Insert the position sensor 61 into. This position sensor 61 is
If the phase switching information of the plate 21 is a light/dark pattern, for example, a phototransistor is used, and the plate 21
If the plate 21 is provided with six steps, a distance sensor is used, and if the plate 21 is a magnetic recording medium and the phase switching information is magnetically recorded, a head such as an MR element is used.

The position sensor 61 includes a signal amplifier 62, a motor position detection circuit 639, an energizing phase switching circuit 64. Index detection circuit 65. A reference speed signal generation circuit 66, a speed control section 67, and an auxiliary drive circuit 60 including a spindle motor rotation control section 68 are connected, and the output of the spindle motor rotation control section 68 is inputted to a power supply line 75D to a coil 75 to control the spindle. Controls the rotation of the motor 20. The operation of this auxiliary drive circuit 60 will be explained below.

The output corresponding to the pattern on play 1-21 read by the position sensor 61 is amplified by the signal amplifier 62 and input to the motor position detection circuit 63 and the index detection circuit 65. When the pattern has six levels as described above, the six levels can be identified by inputting five types of threshold values to the motor position detection circuit 63. By detecting this six-stage pattern, the motor position detection circuit 63 detects the position of the magnet, that is, the rotational position of the rotor, and the detection signal is input to the energization phase switching circuit 64. In the energizing phase switching circuit 64, the coil 2 is energized depending on the position of the rotor.
5 is selected, and the switching signal is sent to the spindle motor rotation control section 68.

On the other hand, the index detection circuit 65 extracts an index signal from the six level signals, and sends this index signal to the speed control section 67.

A reference speed signal from the speed reference signal generation circuit 66 is input to the speed control section 67, and the speed control section 67 detects an error between this reference speed signal and the index signal. This error signal is then sent to the spindle motor rotation control section 68.

Then, in the spindle motor rotation control section 68, the spindle motor 20 is
A drive signal for the coil in the spindle motor 20 is generated.
is rotated accurately.

As described above, according to the present invention, even if any of the Hall ICs fails and the rotor magnet position cannot be detected, the position sensor and the auxiliary drive Since the spindle motor 20 can be rotated correctly using the circuit, the disk 7
It is possible to rescue the data written in 4 without damaging it.

〔Effect of the invention〕

As explained above, according to the present invention, in an outer ring rotating type spindle motor, the spindle motor can be accurately controlled in rotational speed and phase even in the event of a Hall IC failure, without increasing the cost of individual magnetic disk drives. This has the effect that the data written on the disc can be saved without damaging it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of a magnetic disk drive motor of the present invention, FIG. 2 is a sectional view showing the configuration of an embodiment of the magnetic disk drive motor of the present invention, and FIG. 3 is a diagram of the plate shown in FIG. 2. A bottom view of an example, FIG. 4 is a waveform diagram showing the installed state of the plate in FIG. 2 in comparison with the output position of a conventional Hall IC, and FIG. 5 is a configuration of play 1- of another embodiment of the present invention. FIG. 6 is a block diagram showing the configuration of an example of a method for controlling a magnetic disk drive motor according to the present invention when a Hall IC fails, and FIG. 7(a) is a configuration of a conventional magnetic disk drive motor. 7(a) is a bottom view of the magnet in (a), FIG. 7(C) is a plan view of the Hall IC and support disk in (a), and FIG. 8(a) is a bottom view of the magnet in (a). FIG. 8(b) is a waveform diagram showing the detected output waveform of the Hall IC at the position of FIG. 8(a). 1.71... Fixed shaft, 2.72... Bearing, 3.73... Rotor, 4.74... Magnetic disk, 5.75... Coil, 6.76... Magnet, 8...Position sensor, 9.79...Housing. 10... Motor control unit, 11, 21... Position identifier (plate), 31...
Through hole, 60... Auxiliary drive circuit, 61... Position sensor, 78... Hall IC. The principle configuration diagram of the present invention (Fig. 1) Figure 2 (Q) (b) (C) The conventional spindle motor (Fig. 7)

Claims (1)

[Claims] A plurality of stator coils (5) provided on the outer peripheral surface of a fixed shaft (1) fixed to a housing (9) and a bearing (2
) is rotatably supported by the fixed shaft (1) via the
A rotor (with a magnetic disk (4) on the outer periphery and a plurality of permanent magnets (6) on the inner periphery facing the coil (5)
3), a plurality of position sensors (8) provided inside the rotor (3) so as to face the permanent magnets (6) via the support member (7), and an output signal of the position sensors (8). In a magnetic disk drive motor equipped with a motor control unit (10) that controls energization to a plurality of coils (5) based on Position identifier (11) corresponding to the pattern
A motor for driving a magnetic disk, characterized in that the motor is provided concentrically with a fixed shaft (1) and corresponding to the position of a magnet (5).