JPS6059568A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To drive a spindle motor in a magnetic disc device with less variation of revolution by controlling spindle motor driving current in accordance with the difference of a current turning speed and a prescribed turning speed in a position detecting period. CONSTITUTION:When the spindle motor 2 of the disc 1 starts, a counter 7 is reset by a microprocessor 21 at the leading edge of a pulse generated by a position detecting circuit 3 and the counter 7 is similarly reset at the leading edge of successive pulses. The period corresponding to the turning speed of the motor 2 is calculated by the counter 7 counting up clocks. The processor 21 calculates the difference between the counted value and a periodical value corresponding to a prescribed rotational frequency and a current limiting circuit 23 is controlled in accordance with the difference value through a D/A converter 22 to feed back and control the driving current of the motor 2. Consequently, a fixed current is applied for one period of a position detecting signal and the spindle motor of the magnetic disc device can be driven with less variation of revolution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention J] This invention relates to improvements in magnetic disk drives.

[Prior art]

Conventionally, there has been a spindle motor drive circuit of this type for a magnetic disk device as shown in FIG.

In the figure, (1) is a magnetic disk, (2) is a spindle motor that rotates the magnetic disk (1), and (3) is a spindle motor that rotates the magnetic disk (1).
(1) A position detection circuit for detecting the rotational position of the spindle motor (2), (4) a position detection circuit for rotating the spindle motor (2) by the output signal of the position detection circuit (3). A driving pulse generation logic circuit that generates pulses, (5) a differential pulse generation circuit that differentiates and outputs the output of the position detection circuit (3), (6) an oscillator, and (7) the differential pulse generation circuit ( 5) A counter that is reset by the output of the oscillator (6), counts the output pulses of the oscillator (6), and generates an output pulse when a predetermined value is counted.

(8) is a D type flip-flop which uses the output of the counter (7) as data and the output pulse of the differential pulse generation circuit (5) as a clock; (91 instructs the spindle motor (2) to start and stop; start circuit.

01 is an AND gate that outputs the AND of the output of the D type flip 70 tube (8) and the output of the start circuit (9), and 0υ is the AND gate that outputs the output of the drive pulse generation logic circuit (4). The gate circuit is gated by the output of
This is part of the power that causes the drive current to flow through the spindle motor (2).

7(2) Next, the operation will be explained. When the start circuit (9) instructs the spindle motor (2) to stop, the output is L.
OW (hereinafter referred to as III, 11), the D type flip-flop (8) is set, but the AND gate OI maintains Ill, 11, and the gate circuit (Ill is the drive pulse generation logic circuit (4)). To gate the output,
The output becomes II T, 11, and the power part +13 does not flow current to the spindle motor (2).0 Then, when the start circuit (9) output becomes r(igh (hereinafter referred to as IIHII))K, the AND gate OI output also becomes II HII is the gate circuit (Ill is the drive pulse generation logic circuit (4
) through the output, a part of the power is operated, and the spindle motor is rotated. On the other hand, the counter (7) is reset by the output of the differential pulse generation circuit (5), but if it has already counted a predetermined value at this time, the output will be II HII
, otherwise IIT, n. When the rotational speed of the spindle motor (2) is slower than the predetermined speed, the output of the counter (7) is If HII, and the output of the D type flip-flop (8) is also Suga I HII, so the AND gate OI is also IIH + l, Syl. Therefore, the gate circuit 011 transmits the output of the drive pulse generation logic circuit (4) to (3) part of the power 0''A, thereby accelerating the spindle motor (2). Conversely, the rotation speed of the spindle motor (2) is maintained at a predetermined speed. If the speed is faster than II, the output of counter (7) is II
1. II, D type flip-flop (8)
The output is also If I, If, so the AND gate (
l (1 output is also Ill, II, so the gate circuit (
11) transmits the output of the drive pulse generation logic circuit (4) to part of the power 7c. Therefore, the spindle motor (2
), no current flows at all and decelerates.

Since the spindle motor drive circuit of a conventional magnetic disk device is constructed as described above, when accelerating the spindle motor, current continues to flow until a pulse of the 9th order position detection signal is generated.

In the case of deceleration, no current is passed until the next position detection signal pulse occurs, so current must be supplied intermittently to maintain the specified rotation speed, resulting in rotation fluctuations. It had some drawbacks, such as being awkward.

[Summary of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional system (4), and it detects the difference between the current rotational speed and a predetermined rotational speed until the 9th pulse of the position detection signal is generated. It is an object of the present invention to provide a magnetic disk device having a spindle motor drive circuit that has a small fluctuation per revolution by passing a corresponding current.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Second
In the figure, (1) is a magnetic disk, and (2) is a spindle motor that rotates the magnetic disk fil.

(3) is a position detection circuit that detects the rotational position of the spindle motor (2), and (4) generates a pulse for rotating the spindle motor (2) based on the output signal of the position detection circuit (3). Drive pulse generation logic circuit,
Qυ is a microprocessor that detects the rotation speed of the spindle motor (2) from the output signal of the position detection circuit (3) and generates one rotation speed control information, and (9) instructs the spindle motor to start and stop. start circuit,
(6) is the oscillator, and (7) is the microprocessor CD mentioned above.
(2) is a D/A converter that converts the digital rotational speed control information from the microprocessor (QI) into analog; (12 is the drive pulse); Part of the power that causes the drive current to flow through the spindle motor (2) by the output of the generation logic circuit (4), (c) is the part of the power 0''I
This is a current limiting circuit that limits the drive current of J by the output of the D/A converter (a).

Next, the operation will be explained. If the start circuit (9) instructs the spindle motor (2) to stop, the signal is passed through the microprocessor clυ.

By being transmitted to the drive pulse generation logic circuit +41, no drive pulse is generated and the spindle motor (2) does not rotate.

Next, the start circuit (9) starts the spindle motor (2).
When the signal is transmitted to the drive pulse generation wheel IP circuit (4) through the microprocessor sash υ, a drive pulse is generated, and the current limit circuit (c) adjusts the drive pulse to a predetermined value. The set starting current flows to the spindle motor (2) and it begins to rotate.

When the rotation starts, a pulse is generated in the 2-position detection circuit (3), and at the rising edge of the pulse, the microprocessor CD
resets the counter (7) and starts counting.When the output pulse of the zero-order position detection circuit (3) rises -J2, the microprocessor 0111 takes in the value of the counter (7) and then resets it. and start counting again. The microprocessor CD outputs a digital value corresponding to the current value to be output based on the value taken in from the counter (7).
/A converter output. The D/A converter (D/A converter) converts the output of the microprocessor Ql) into analog data and outputs it to the current limiting circuit (c). Current limit circuit (
C) limits the current of the power section 03 by the output of the D/A converter (2). This current is transferred to the next position detection circuit (
The output pulse of the zero-order position detection circuit (3), which is maintained until the output pulse (3) rises, repeats one or more operations upon the rise to control the rotation of the spindle motor (2). Here, a specific example of the relationship between the value of the counter (7) and the output current will be shown.

It is assumed that the counter value corresponds to a deviation from a predetermined number of rotations. In Fig. 3, L30 is a spindle motor (2
) The vertical axis represents the drive current (in amperes).

(y) 03 is the horizontal axis representing rotational deviation (unit: percentage).

(g) is a graph showing the control output current corresponding to the rotational deviation.

In the above embodiment, the value of the counter (7) is taken in.

The example shown uses a microprocessor Qυ to output rotation control information to the D/A converter 03.

It may be configured using TTL or other logic To.

〔Effect of the invention〕

As described above, according to the present invention, in the rotation control of the spindle motor, by flowing a constant current during one cycle of the two-position detection signal, it is possible to obtain a spindle motor with little variation in two rotations.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional spindle motor drive circuit, Fig. 2 is a block diagram of a spindle motor drive circuit according to an embodiment of the present invention, and Fig. 3 is a control current for rotational deviation of the spindle motor drive circuit according to the present invention. This is a graph of fil...Magnetic disk, (2)...Spindle motor, (3)...Position ft detection circuit, (4)...Drive pulse generation logic circuit. (8) (6)...Oscillator, (7)...Counter, (9)...
...Start circuit. a3...Power part, QD...Microprocessor,
(a)...D/A converter, @...current limit circuit. In addition, in FIG. 1, the same reference numerals indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1

Claims (1)

[Claims] In a spindle motor that rotates a magnetic disk based on a position detection signal, the cycle of the position signal is measured, and a current is supplied according to the difference between the cycle and a rotation cycle corresponding to a predetermined rotation speed. A magnetic disk device characterized in that rotation control is performed by constantly supplying a first position 1u detection signal to the spindle motor during one cycle.