JPS6352371A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To secure a certain servo area and a certain data area even if the pulse width of an index pulse is changed, by providing a clock means which obtains time intervals of index pulses and an area prescribing means. CONSTITUTION:An area prescribing means 41 prescribes the rise of the index pulse as the start time of the servo area, and a clock means 40 obtains a time t1 from the rise to the fall of the index pulse. A reference time t0 is preliminarily stored in the area prescribing means 41, and the means 41 compares this reference time t0 with the measured time t1. In case of t0<t1, the fall of the index pulse is prescribed as the end time of the servo area. The end of the servo area corresponds to the start of the data area, and the time t1 from the actual rise to the fall of the index pulse is prescribed as the servo area as it is. In case of t0>t1, the fall of the index pulse is forcibly delayed to extend the time to the fall to the time t0. Thus, the required minimum servo area is secured even if the actual width of the index pulse is extremely shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention generates one index pulse for each rotation of the disk, and defines the index servo area and controls the rotation of the disk drive motor based on the index pulse. The present invention relates to a magnetic disk device that performs number control.

[Prior Art] This type of magnetic disk drive is called an index servo control system, and one of the methods has conventionally been to control the rise to fall of one index pulse (or
A method has been considered in which the time period from the falling edge to the rising edge of the index pulse is defined as a servo area, and a command to start writing or reading from the disk is sent to the controller at the falling edge (or rising edge) of the index pulse. In the case of the magnetic disk drive, a magnetic sensor, a Hall IC, etc. detect changes in the magnetic field received from a magnet that rotates together with a spindle motor for rotating the disk.
This generates an index pulse, and the pulse period is measured to control the rotation speed of the spindle motor. In this method, within one period of the index pulse,
In other words, during the limited time period in which the disk rotates once,
It is necessary to define a data area and a servo area.

Incidentally, in such a magnetic disk device, the servo area is defined in direct correspondence to the width of the index pulse. Therefore, it was necessary to define the width of the index pulse with high precision.

[Problems to be Solved by the Invention] However, the above-described conventional magnetic disk device has the following problems. In other words, the width of the index pulse varies depending on various factors such as the magnetic force and dimensions of the magnet used to generate the index pulse, the gap between the magnet and the Hall IC, the sensitivity of the Hall IC, the mounting orientation, temperature characteristics, and voltage fluctuations. Cheap. Therefore, it is difficult to define the width of the index pulse with high precision. If the width of the index pulse cannot be defined with high precision, for example, if the width of the index pulse becomes longer and the servo area becomes longer than a predetermined value, it will inevitably become impossible to secure the time required for the data area. Furthermore, if the width of the index pulse becomes short, the time necessary for the servo area cannot be secured, and servo information cannot be recorded or reproduced.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a magnetic disk device that can guarantee a constant servo area and data area even when the index pulse width changes due to various factors.

[Means for Solving the Problems] The present invention generates one index pulse for each rotation of the disk, and defines the index servo area and controls the rotation speed of the disk drive motor based on the index pulse. In a magnetic disk drive that performs the above-described magnetic disk drive, there is provided a clock means for determining the pulse width of the index pulse and a time interval between the index pulses, and a clock means for determining the pulse width of the index pulse determined by the clock means, and a timer whose determined pulse width is a predetermined width based on the pulse width of the index pulse determined by the clock means. When the pulse width is smaller than the predetermined width, a servo area of a size corresponding to the predetermined width is defined, and when the obtained pulse width is larger than the predetermined width, a servo area of a size corresponding to the obtained pulse width is defined. and a rotation control means for controlling the number of revolutions of the disk drive motor so as to keep the interval constant based on the time interval between index pulses determined by the timer. It is something.

[Operations] According to the present invention, the rotational speed of the disk is controlled so as to secure the minimum required search area regardless of the pulse width of the actual index pulse, and to keep the deniter area constant.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 7 are explanatory diagrams of one embodiment of the present invention.

In FIG. 2, reference numeral 1 denotes a magnetic disk device according to this embodiment, and a spindle motor (disk drive motor) 3 is attached to the lower side of a base 2 of this magnetic disk device 1. A shaft 4 of this spindle motor 3 is rotatably attached to a spindle motor body 6 via a bearing 5, and this spindle motor body 6 is attached to a base 2.
is fixed to the bottom of the A support stand 7 is provided on the lower surface of the spindle motor body 6, and a hole I is provided in this support stand 7.
C (detection means) 8 is fixed.

Further, a rotor 9 is attached to the lower end of the shaft 4. A ring magnet 10 is fixed to the inner circumferential wall of the rotor 9, and one magnet it is embedded in the outer circumferential wall so as to face the hole I08 with a slight gap therebetween.

Further, a hub 12 is fixed to the upper end of the shaft 4, and two disks l3. +4 is spacer 1
5, and is tightened and fixed by a clareb 16.

A control system as shown in FIG. 1 is connected to such a spindle motor 3. In the figure, 40 is a clocking means;
Reference numeral 41 represents area defining means, and reference numeral 42 represents rotation control means. These functions will be described later along with their actions.

Returning to FIG. 2 again, 20.21 is a magnetic head that writes/reads to both sides of the disk 13, 22.23 is a magnetic head that writes/reads to both sides of the disk 14, and these are the load arms. It is fixed to the arm 25 via 24. The arm 25 can slide in the left and right directions in the figure via a slider bearing 26. This causes the magnetic heads 20 to 23 to perform a seek operation. Note that 27 is a cover that covers the magnetic disk device l, and 28 is a control board.

Next, the effect will be explained.

Every time the spindle motor 4 rotates once, the magnet 11 faces the Hall IC 8. The Hall IC 8 detects the change in the magnetic field at this time and outputs one index pulse for each rotation of the disk. This index pulse is used to define a servo area and a data area.

Therefore, first, the definition of the servo area will be explained using reading as an example.

FIG. 5(a) shows the read waveform of the magnetic head as the disk rotates, where d is servo data and d2 is data. The servo data d1 is read out in synchronization with the index pulse, and in order to completely read out the servo data d, it is necessary to define a servo area with a sufficient time longer than a predetermined period. The servo data d
The minimum time required to read 1 is the reference time t. shall be.

In defining the servo area, first, the area defining means 4
1 defines the rising edge of the index pulse as the start time of the servo area (see FIG. 5(b)). Timing means 40
calculates the time Ll from the rise to the fall of the index pulse in the figure. The area defining means 41 stores the reference time E0 in advance, and the reference time t. and the measured time t obtained by the timer 40 are compared.

And 1. <1. In this case, the falling edge of the index pulse is directly defined as the end of the servo area.

The end of this servo area also becomes the start of the data area. Therefore, the time t1 from the actual rise to the fall of the index pulse is directly defined as the servo area. FIG. 5(B) shows the case where tl is relatively long, and FIG. 5(C) shows the case where t is relatively short. In this case, the only difference between the disk rotation periods T i and T t is that the minimum necessary servo area and a certain data area are secured for both disks. At the falling edge of the index pulse, a read command signal is sent to a controller (not shown), which instructs the controller to start reading data from the data area.

On the other hand, when to>t+, the falling edge of the index pulse is forcibly extended to t. shall be. Therefore, even if the actual width of the index pulse becomes extremely short, the minimum necessary servo area is secured.

In this way, by securing and defining the minimum necessary servo area, the servo data d can be reliably read.

Furthermore, the index pulse is also used to control the rotation speed of the spindle motor 3. Next, control of the spindle motor 3 will be explained.

First, the clocking means 40 calculates the time corresponding to the data area from the falling edge of the index pulse, and the rotation control means 42 controls the rotational speed of the spindle motor 3 so as to keep the time of the data area constant for a predetermined time t2. control. Of course, the predetermined time t2 is sufficient time to read the data d2. Therefore, a sufficient and constant data area is secured.

Incidentally, factors that cause the actual width of the index pulse to change include changes in the detected magnetic field due to reasons such as the positional relationship between the Hall IC 8 and the magnet 11, and changes in the sensitivity of the Hall IC 8. Figure 6 shows the change in the magnetic field detected by the curator. When the detected magnetic field changes (S m+=S mz) as shown in (A) of the same figure, the actual index pulse changes from (B) to (C) of the same figure. On the other hand, the latter case of sensitivity change of the Hall IC 8 is shown in FIG. As shown in the same figure (a), the sensitivity change (V, -VZ) of Hall IC8
Accordingly, the actual index pulse is as shown in the same figure (b) (
Changes to c).

What about this invention? As described above, it is possible to secure the minimum necessary servo area and a constant data area regardless of changes in the actual width of the index pulse.

Note that the configuration of the index pulse generating means is not limited to the equivalent embodiment described above. For example, instead of the magnet X1 and the Hall IC 8, as shown in FIG. 8, a hole 9a provided in the outer wall of the rotor 9 of the spindle motor 32 and a magnet sensor 33 for detecting the hole 9a may be used. In this example, the magnet sensor 33 includes a magnet 33a and a coil 33b.

[Effects of the Invention] As explained above, according to the present invention, the minimum necessary servo area is secured by the area defining means regardless of the size of the actual index pulse panosis width, and the data area is kept constant. Since the rotation speed of the disk is controlled by the rotation control means, the following effects can be achieved.

(1) Since the pulse width of the index pulse can always be secured for the necessary and sufficient time to define the servo area, regardless of its size, highly accurate index servo control can be realized.

(2) Even if the actual pulse width of the index pulse changes due to various factors such as temperature changes and voltage fluctuations, a constant data area can be secured.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a sectional view showing the configuration of an embodiment of the present invention, and FIGS. 3 and 4 are, respectively,
A sectional view and a plan view showing the configuration of the spindle motor 3 according to the present embodiment, FIG. 5 is a time chart showing the relationship between the read waveform of the magnetic head and the index pulse, and FIG. 6 is a time chart showing the relationship between the magnetic field change and the index pulse width. A time chart showing the relationship, FIG. 7 is a time chart showing the relationship between the sensitivity change of the Hall IC 8 and the width of the index pulse.
The figure is a sectional view showing the configuration of the main parts of the embodiment of the pond of the present invention. 3. Spindle motor (disk drive motor),
8... Hall IC (detection means), 40... Time measurement means, 4I... Area defining means, 42...
Rotation control means. Applicant Tokiko Co., Ltd. Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] A magnetic disk device in which one index pulse is generated every rotation of a disk, and the index servo area is defined based on the index pulse and the rotation speed of a disk drive motor is controlled. a timer for determining the pulse width of the pulse and the time interval between the index pulses; and based on the pulse width of the index pulse determined by the timer, if the determined pulse width is smaller than a predetermined width, the time interval is determined by the predetermined width. area defining means for defining a servo area of a corresponding size and, when the determined pulse width is larger than the predetermined width, defining a servo area of a size corresponding to the determined pulse width; A magnetic disk drive comprising: rotation control means for controlling the number of revolutions of the disk drive motor based on the time interval between index pulses determined by the means so as to keep the interval constant.