JPH03183395A - Magnetic disc unit - Google Patents

Abstract

PURPOSE:To drive a three-phase brushless DC motor, provided with no position sensor, accurately by providing means for applying an impulse voltage corresponding to the excitation pattern of a spindle winding, an A/D converter, and a driving means. CONSTITUTION:A magnetic disc unit comprises means 3 for applying impulse voltages in plural types of exciting pattern onto respective phases of spindle windings 4a-4c, means 5a-5c for sustaining response voltages induced in the spindle windings 4a-4c, an A/D converter 7 for converting respective response voltages into digital signals, and means 2 for selecting the maximum response voltage and determining the exciting phase at the time of start based on the corresponding excitation pattern thus driving a magnetic disc. When a DC brushless spindle motor employing no position sensor is started, pulse driving is carried out and the exciting pattern at the starting time is detected based on the difference of impulse response. By such arrangement, reverse rotation is prevented at starting time and the head or the medium material in the unit can be protected against breakdown.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spindle motor for a magnetic disk drive, and more particularly to a magnetic disk drive that can accurately drive a three-phase brushless DC motor without a position sensor.

[Conventional technology]

Conventionally, in order to start the spindle motor of this type of magnetic disk drive, one of six patterns for excitation of the spindle motor is selected in advance by a microprocessor, etc., and the phase of that pattern is forcibly activated. Excite. Thereafter, by sequentially excitation in the rotational direction, the spindle motor is rotated synchronously and started.

[Problem to be solved by the invention]

In the conventional magnetic disk drive described above, the position sensor is omitted, so when starting the spindle motor, the phase that is first excited does not match the original rotation direction, so the spindle motor rotates up to 45 degrees in the opposite direction. There is. For this reason,
It has the disadvantage of damaging the head and medium.

[Means to solve the problem]

A magnetic disk drive according to the present invention includes means for applying impulse voltages according to a plurality of types of excitation patterns to each phase of a spindle winding, means for holding a response voltage generated in the spindle winding, and a means for transmitting each response voltage into a digital signal. and a means for selecting the maximum value of the response voltages, determining an excitation phase at startup using the excitation pattern, and driving the motor.

[Effect]

According to the present invention, even if a DC brushless motor that does not use a position sensor is used as a spindle motor of a magnetic disk device, it can be started accurately.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device according to the present invention. In the figure, 1 is shown in Figure 2 (a
) to a microprocessor 2 outputting the excitation signals PHA-PHC shown in FIG.
- A logic circuit that operates according to the PHC input and outputs a drive signal according to a 6wi excitation pattern, 3 is a spindle winding 4a of a DC brushless motor that is a spindle motor.
A driver that sends current to 4C, 5a to 5C are capacitors,
6&~6C are resistors, and 7 is an A/D converter that digitally converts the voltage held in the capacitors 5~5C.

Next, the operation of the magnetic disk device with the above configuration and the phase from which excitation is started to start up the magnetic disk device will be explained. The microprocessor 1 is shown in FIGS. 2(a) to 2.
Excitation patterns A to F of white types are created using the excitation signal PHA-PIC shown in FIG. On-excitation pattern C
off, excitation pattern D on - excitation pattern D off, excitation pattern E on - excitation pattern E off, excitation pattern F on - excitation pattern F off using logic circuit 2.
Output to. This logic circuit 2 operates based on the input of these six types of excitation patterns A to F, and outputs a drive signal to the driver 3. Therefore, the driver 3 operates upon input of this drive signal, and causes a pulsed current to flow through the spindle windings 4a to 4c. At this time, the DC brushless motor does not rotate and the current is pulsed to the spindle winding 4 at a fast period of about h.
When the voltage is applied to m to 4C, a voltage impulse response occurs in the spindle windings 4a to 4c, and when this response converges, the response voltage is held in the capacitors 5a to 5c. Then, the A/D converter 7 digitally converts the voltage held in the capacitors 5 & ~5c to the microprocessor 1.
Output to. This microprocessor 1 takes in this digitally converted data for six types of excitation patterns A to F, and stores it in an internal memory (not shown). and,
To explain with reference to FIGS. 3 and 4, the microprocessor 1 drives the excitation pattern A for a driving time t in step S, turns off the excitation pattern A in step S2, and turns off the excitation pattern A in step S3. Input the digital value of response voltage v1. Then, operations similar to those described above are performed from step S4 to step Soi.

Here, due to the structure of the DC brushless motor, the magnetic permeability of the t-root core changes depending on the magnetic flux of the rotor.

As a result, the inductance of the spindle windings 4a to 4C changes depending on the position of the rotor, so the impulse response voltage changes and the response St pressure v1 to 4C when it is converged.
Changes occur in v6. As a result, when starting the spindle motor, the response voltage in the pattern in which current must flow is the highest, so the microprocessor 1 compares the magnitudes of the response voltages 1 to V@ in step SIO, and performs step SIO. By starting excitation from the phase of the pattern that shows the maximum value, the sysmondor motor can be started accurately.

〔Effect of the invention〕

As explained in detail above, according to the magnetic disk device according to the present invention, pulse drive is performed when starting a DC brushless spindle motor that does not use a position sensor,
By detecting the excitation pattern at startup based on the difference in impulse response at that time, it is possible to prevent reverse rotation at startup and protect the head and medium of the device from damage.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device according to the present invention, FIG. 2 is a diagram showing an excitation pattern for driving the spindle motor shown in FIG. 1, and FIG. 3 is a diagram showing the operation of FIG. 1. Flowchart for explaining, Figure 4 is the first
FIG. 3 is a diagram showing the magnitude of a response voltage when the spindle winding shown in the figure is pulse-driven. 1...Microprocessor, 2...Logic circuit,
3...Driver, 4a~46@...Spindle-
II, 5a-5e... Capacitor, 6a-5c...
...Resistance, 7...A/D converter.

Claims (1)

[Claims] In a magnetic disk device that uses a DC brushless motor as a spindle motor without using a position sensor,
means for applying impulse voltages according to a plurality of types of excitation patterns to each phase of the spindle winding; means for holding the response voltage generated in the spindle winding; and an A/D converter for converting each response voltage into a digital signal. , a means for selecting the maximum value of the response voltages, determining an excitation phase at startup based on the excitation pattern, and driving the magnetic disk device.