JPH03270668A - Magnetic disc drive motor - Google Patents

Abstract

PURPOSE:To improve controllability by an arrangement wherein a position detector opposing to the rotational orbit of a position identifier detects an analog amount in response to the position identifier and conduction control of a plurality of coils is carried out based on an output signal from the position detector. CONSTITUTION:A motor position detecting circuit 63 detects patterns in six stages thus detecting the rotational position of a rotor. A conduction phase switching circuit 64 selects a coil to be conducted according to the position of rotor. An index detecting circuit 65 extracts an index signal from level signals in six stages. A speed control section 67 detects the error between a reference speed signal and the index signal, and a spindle motor rotation control section 68 produces a coil driving signal for a spindle motor 60 based on a coil phase switching signal fed from the conduction phase switching circuit 64 and an error signal fed from the speed control section 67 thus driving the spindle motor 60 with high rotational accuracy.

Description

[Detailed Description of the Invention] [Summary] Regarding a disk drive motor for a magnetic disk device, the present invention aims to provide a magnetic disk drive motor that can perform rotational speed control and phase M control with a simple configuration. The disc motor consists of a fixed shaft fixed to the housing, multiple coils attached to the outer circumference of the fixed shaft, a rotor rotatably supported by the fixed shaft via bearings, and attached to the outer circumference of the rotor. a fixed magnetic disk, a plurality of permanent magnets attached to the inner peripheral surface of the rotor so as to face the coils, and a plurality of permanent magnets arranged so as to be concentric with the fixed shaft and corresponding to the positions of the magnets.
Based on a position identifier provided on the rotor, a position detector provided in the housing opposite to the rotation locus of the position identifier and detecting a change in analog quantity in response to the position identifier, and an output signal of the position detector. and a motor control section that controls energization of the plurality of coils.

[Industrial application field]

The present invention relates to a magnetic disk drive motor, and more particularly to a magnetic disk drive motor that can perform rotational speed control and phase control with a simple configuration.

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. Therefore, there is a need for a magnetic disk motor that can obtain highly accurate phase switching signals and index signals for detecting rotational speed, and that has a simple structure.

[Conventional technology]

FIG. 7(a) shows the configuration of a three-phase type brushless spindle motor of a conventional magnetic disk device. In the figure, 79 is a housing of a magnetic disk device,
A fixed shaft 71 of a spindle motor 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. 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 periphery of the fixed jaw 7) 71 inside the rotor 73, and on this support disk 77, a plurality of Hall elements, Alternatively, a Hall IC 78 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 Hall IC 78 are
It was drawn out of the housing 79 through a thin hole provided in the fixed shaft 71.

FIG. 7(b) 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 the position of the Hall IC 78 mounted on the support disk 77 when the magnet 76 has four poles. In this example, holes I and C are 78
There are three, A, 78B, and 78C, and they are arranged at 60° intervals.

FIG. 8(c) shows the magnet 76 shown in FIG. 7(a) and the hole ICs 78A, 78B, 78 when the hole ICs 78A, 78B, 78C are as shown in FIG. 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" electrical angle. Conventionally, the Hall IC 78C
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.

The coil 75 of the spindle motor is then
A phase switching signal was obtained.

[Problem to be solved by the invention]

However, as magnetic disk drives become smaller and the radius of the rotor 73 becomes smaller, magnetization errors of the magnets 76,
Moreover, the positioning error of the three permanent ICs 78A, 78B, and 78C for detecting leakage magnetic flux from the magnet 76 becomes large, resulting in a problem of deterioration of rotational speed accuracy. In other words, in order to achieve rotational accuracy, it becomes extremely difficult to manage the magnetization error and the positioning error between the three Hall ICs, and even if you try to obtain an accurate index signal from the Hall signal, it will take one rotation from the previous error. The signal fluctuations during the rotation became very large, and the rotational speed index had to be reduced to 1 pulse/cycle in order to cancel these errors, resulting in a decrease in controllability. Furthermore, three holes IC
Signal lines from 78A, 78B, 78C? 8S and the power line 75D of the coil 75 had to be passed through the thin shaft 71, which left a problem in workability.

The present invention simplifies the management of magnetization errors, increases the rotational speed index during one revolution, improves controllability, and improves controllability.
This is a simple method that eliminates the need to manage positioning errors between two Hall ICs, and eliminates the need to pass three Hall signal signal lines and power lines through the shaft 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 perform rotational speed control and phase control with a simple configuration.

[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. In the figure, fixed shaft 1
is fixed to the housing 9. A plurality of coils 5 are attached to the outer peripheral surface of the fixed shaft 1, and a rotor 3 is rotatably supported via a bearing 2. On the other hand, a magnetic disk 4 is attached to the outer circumference of the rotor 3, and a plurality of permanent magnets 6 are attached to the inner circumference so as to face the coil 5. Furthermore, rotor 3
At a predetermined portion of , there is a
In addition, a position identifier 7 is provided to correspond to the position of the magnet 6, and a position detector 8 is provided in the housing 9 opposite to the rotation locus of the position identifier 7, and is sensitive to the position identifier 7. to detect the analog quantity. Then, the motor control unit 10 controls energization of the plurality of coils 5 based on the output signal of the position detector 8.

[Function] According to the magnetic disk drive motor of the present invention, as the rotor rotates, the position identifier incorporating equally spaced phase switching information (multi-stage position identification signal) corresponding to the position of the magnet is also transferred to the fixed shaft. rotate around. As the position identifier rotates, an analog position detector provides multi-step phase switching information which is converted by a demodulator into a signal compatible with conventional motor control signals. Further, since the multi-stage position identification signals in the position identifier are written at equal intervals, an accurate index signal of seven cycles of multiple pulses can be obtained by differentiating the output of the analog position detector. As a result, the controllability of the magnetic disk drive motor is improved.

〔Example〕

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

FIG. 2 is a sectional view showing the structure of an embodiment of the magnetic disk drive motor of the present invention. In the figure, 29 is a housing of a magnetic disk device, and a fixed shaft 21 made of a magnetic material of a three-phase type spindle motor is fixed to this housing 29. This fixed shaft 21 has two bearings 22.
A cylindrical rotor 23 made of a magnetic material is attached through the shaft, and the rotor 23 can rotate around the fixed shaft 21. A plurality of magnetic disks 24 are fixed to the outer peripheral surface of the rotor 23. on the other hand,
A plurality of magnets 26 are attached to the inner peripheral surface of the rotor 23, and the magnets 26 are attached to the outer peripheral surface of the fixed shaft 21.
A plurality of coils 25 are provided corresponding to the number of coils 25.

The t source line 25D to the coil 25 is drawn out of the housing 21 through a thin hole provided in the fixed shaft 21.

In the magnetic disk drive motor configured as described above, in this embodiment, a ring-shaped plate 27 containing phase switching information is attached to the bottom surface of the rotor 23, and a ring-shaped plate 27 is attached to the bottom surface of the rotor 23. Housing 29
A position detector 28 comprising a single sensing element is provided at.

FIG. 3 shows an example of phase switching information included in the plate 27 of FIG. 2, and the plate 27 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. In this way, if the phase switching information has a fi shading pattern, the second
A single analog detector 28A that recognizes shading is used as the position detector 28 in the figure. The plate 27 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 27. Note that since this shading pattern can be formed by printing, the color density and position can be formed accurately.

Figure 4 shows the analog detector 28A with the shading pattern in Figure 3.
This shows the detection output by Analog detector 28
A, for example, uses a phototransistor to read the 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.

In this embodiment, an index pulse for detecting the rotational speed of the disk is generated at a change point of the analog output. For this reason, the number of index pulses during one revolution of the disk is much larger than in the past.

The analog output and index pulse shown in FIG. 4 are input to a motor control circuit (not shown), and phase switching information and rotation speed information of the coil 25 are demodulated from these signals.

In the above-described embodiment, a six-level pattern of shading was formed on the plate 27, but the positional information of the magnet 26 included in the plate 27 is not limited to shading. FIG. 5 shows another embodiment of the position information of the magnet 26 incorporated in the plate 27.
7 with 6 steps. In this case, a distance sensor may be used as the position detector 28. Furthermore,
It is also conceivable that the plate 27 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.

FIG. 6 shows an example of the configuration of the control circuit for the magnetic disk drive motor of the present invention constructed as described above. In this figure, D indicates a magnetic disk, and 60 indicates a spindle motor. A pattern written at a predetermined location on the spindle motor 60 is read by a pattern detector 61, and its output is amplified by a signal amplifier 62 and input to a motor position detection circuit 63 and an index detection circuit 65.

When the pattern has 6 stages as in the above example,
By inputting five types of threshold values to the motor position detection circuit 63, six levels can be identified.

The motor position detector 11163 detects the six-stage pattern to detect the position of the magnet, that is, the rotational position of the rotor, and the detection signal is sent to the energized phase switching circuit 6.
4 is input. The energized phase switching circuit 64 selects the coil 25 to be energized depending on the rotor position, and sends a switching signal 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 6B, the spindle motor 60 is
A drive signal for the coil in the spindle motor 60 is generated.
is driven with high rotational precision.

As described above, according to the present invention, the rotor magnet position can be detected with one analog detector without using three Hall ICs, which conventionally required three Hall ICs, thereby eliminating the need for three Hall ICs for positioning. At the same time, it becomes unnecessary to pass the Hall signal line through a narrow hole in the fixed shaft. Furthermore, the multi-level information formed in the position identifier allows a large number of accurate rotational speed indices to be obtained from the detector during one rotation of the disk, thereby improving controllability.

〔Effect of the invention〕

As explained above, according to the present invention, in an outer ring rotating type spindle motor, rotation speed control can be achieved with a simple configuration.
This has the effect that phase control can be performed and the controllability of the magnetic disk drive motor can be improved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle configuration of a magnetic disk drive motor according to the present invention, Fig. 2 is a sectional view showing the structure of an embodiment of a magnetic disk drive motor according to the present invention, and Fig. 3 is a diagram showing the structure of an embodiment of the magnetic disk drive motor of the present invention. c') A bottom view of 7'c-1, Fig. 4 is an output characteristic diagram of the detector in Fig. 2, Fig. 5 is a perspective view showing the structure of the plate of another embodiment of the present invention, Fig. 6 7(a) is a cross-sectional view showing the structure of a conventional magnetic disk drive motor; FIG. ) 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 an explanatory diagram showing the positional relationship between the magnet and the Hall IC in Fig. 7, and Fig. 8(b) is a waveform diagram showing the detected output waveform of the Ho sword at the position of (a). .71... Fixed shaft, 2, 22.72... Bearing, 3, 23.73... Rotor, 4, 24.74... Magnetic disk, 5, 25.75... Coil, 6 , 26.76... Magnet, 7.27... Position identifier (plate) 8.28...
Detector, 9, 29.79... Housing, lO... Motor control unit, 78... Hall IC.

Claims (1)

[Claims] A fixed shaft (1) fixed to a housing (9), a plurality of coils (5) attached to the outer peripheral surface of the fixed shaft (1), and fixed via a bearing (2). A rotor (3) rotatably supported by a shaft (1), and a magnetic disk (3) attached to the outer periphery of the rotor (3).
4), a plurality of permanent magnets (6) attached to the inner peripheral surface of the rotor (3) so as to face the coil (5), and a plurality of permanent magnets (6) attached to the inner peripheral surface of the rotor (3) so as to face the coil (5); A position identifier (7) provided on the rotor (3) so as to correspond to the position (5), and a position identifier (7) provided in the housing (9) opposite to the rotation locus of the position identifier (7). 7), and a motor control unit (8) that controls the energization of the plurality of coils (5) based on the output signal of the position detector (8). 10) A magnetic disk drive motor comprising: