JPH03192585A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To improve servo control characteristics by supplying position feedback information obtained by combining position information detected by a position detecting means and the acceleration information of a supporting member detected by an acceleration detecting means to a head driving means. CONSTITUTION:Servo sector information read out by a data head 22 is amplified by a head amplifier 23 and then inputted to a gate array 24. A DSP 15 reads out the contents of a gray code register arranged in the array 24, converts the read contents into a cylinder position and computes the moving speed of a head from the current and past head positions. On the other hand, a detecting signal corresponding to carriage acceleration detected by an acceleration pickup 21 is supplied to the DSP 15. A position signal detected by a detector 25 is also supplied to the DSP 15, both signals are added and combined to form a position feedback signal. The positioning control of the head can be executed by controlling the drive of a VCM 18 by the position feedback signal through a VCM driver 19.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a magnetic disk device used as an external storage means of a computer, and particularly to a magnetic disk device suitable for improving the positioning accuracy of a magnetic head and shortening settling time and access time.

[Conventional technology]

Conventionally, one method of magnetic head positioning control of a magnetic disk device is
One type of sector servo control is sector servo control, and in this sector servo control, for example, by using a zero-order hold circuit as shown in FIG. I'm holding it until then. The output waveform of the zero-order hold circuit is shown in FIG. 7(b). By the way, in the position information reproduction system in the sector servo control described above, the interval time and sampling time of each servo sector are the same. In this case, the sampling time is Ts
Then, the upper limit of the frequency of the reproducible head position signal is π/Ts (rad/s).

[Problem to be solved by the invention]

However, the conventional magnetic disk device as described above has the following problems. That is, according to the well-known sampling theorem, a position signal that is a digital signal has a problem in that components having a frequency (ω>π/T s ) higher than the Nyquist frequency cannot be reproduced. In this case, ωs
/2-π/Ts is generally called the Nyquist frequency. On the other hand, components above the Nyquist frequency cause aliasing as shown in FIG. 8, which affects the frequency region below the Nyquist frequency as an aliasing error. Therefore, conventionally, as shown in FIG. 9, for example, the signal shown in FIG. 7(b) is input to the anti-aliasing filter 2 of a DSP (digital signal processor) 1 to perform anti-aliasing processing, and from the filter 2, the signal shown in FIG. It was outputting a position feedback signal. Therefore, the rotation speed is 260O
rpm, the number of sector servos is 45, the sampling time is 500 μsec, and the Nyquist frequency is IKz, but the phase delay is large at the Nyquist frequency, so the servo band is at most 200 Hz ('', Nyquist frequency 15 ) was the limit. Now, in order to improve servo control, it is necessary to increase the number of servo sectors and shorten the sampling time, but the number of servo sectors is determined by the constraints of the interface of the magnetic disk device. In addition, increasing the number of servo sectors inevitably reduces the data area, and in the end, there is a limit to how much the number of servo sectors can be increased. An object of the present invention is to provide a magnetic disk device that achieves improved servo control characteristics without being subject to interface restrictions or reducing the data area due to an increase in the number of servo sectors.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a magnetic disk drive employing a sector servo control method, including a head drive means for controlling drive of a magnetic head based on position feedback information, and a head support member for supporting the magnetic head. an acceleration detection means for detecting the acceleration of the head support member; a position detection means for detecting the position of the magnetic head based on servo sector information written in a servo sector; and a position of the magnetic head detected by the position detection means. The apparatus is characterized by comprising a control means for supplying position feedback information, which is a combination of information and acceleration information of the head support member detected by the acceleration detection means, to the head drive means.

[Operation 1] According to the present invention, the head drive means is driven based on position feedback information obtained by combining the position information of the magnetic head detected by the position detection means and the acceleration information of the head support member detected by the acceleration detection means. , positioning the magnetic head. [Embodiment] An embodiment of the present invention will be described below based on the drawings. In FIGS. 1 and 2, a magnetic disk 10 mounted in a magnetic disk device to which a data surface sector servo control method is applied has a rotating direction (rotational speed: 26 GOr).
pm), 45 servo sectors 11 are arranged radially, and each of these servo sectors 11 is connected to the ODD.
EVEN area 12, GRAY C0DE area 13
, and an AM area 14 for detecting servo sector information. In this case, the track position of the magnetic head is changed from the GRAY C0DE area 13 to the ODD.
The detailed position of the magnetic head within the track is detected from the EVEN area 12, and based on the detection result, a DSP (to be described later) calculates the amount of positional deviation/moving speed of the magnetic head. In addition, the sector servo control system of this magnetic disk device has a third
It is configured as shown in the figure. That is, signals are supplied from pin DAC1 and bin DAC2 of a DSP (digital signal processor) 15 that controls each part of the sector servo control system to a comparator 16, and the output signal of the comparator 16 is amplified by an amplifier 17 and then magnetically VCM for head drive
(Voice coil motor) 18 is supplied to the VCM driver 19 which drives and controls the output signal of the VCM driver 19, and after being amplified by the amplifier 20, it is input to the analog input pin AN2 (A/D conversion) of the DSP 15. It has become. In addition, the acceleration signal of the carriage output from the acceleration pickup 21 attached to the carriage (shown path, head support member) that supports the magnetic head is DS.
The reference voltage Vrer is input to the analog input pin AN3 (A/D conversion) of the DSP15, and the reference voltage Vrer is input to the analog input pin ANo (A/D conversion) of the DSP15. Further, the servo information signal read from the servo sector 11 of the magnetic disk 10 by the data controller 22 is amplified by the head amplifier 23. Furthermore, the output signal of the head amplifier 23 is output from the gate array 2.
4, and the output signal of the gate array 24 is supplied to the DSP
15. Further, the head position signal detected by the detector 25 is input to an analog input bin ANI (A/D conversion) of the DSP 15. Further, to explain the configuration inside the DSP 15 with reference to FIG. 4, the analog input bin AN from the acceleration pickup 21 is
The acceleration signal input to 3 is passed through an anti-aliasing filter 30 with a time constant of 2 T s (bandwidth: ω=π/T s
(red/s)), and after performing two time integrations to convert the acceleration signal into a position signal, it is passed through a bypass filter 31 with a time constant of 47 s, and then passed through a summing point 32. It is designed to be supplied to On the other hand, the analog manual pin ANI from the detector 25
The input position signal is passed through an anti-aliasing filter 33 with a time constant of 4Ts (bandwidth: ω=yr/2T
After anti-aliasing processing is performed by s (red/s)), the signal is supplied to the addition point 32. Then, the two signals are added and combined at the addition point 32, and are finally supplied to the VCM driver 17 as a position feedback signal. Next, the operation of the magnetic disk device of this embodiment with the above configuration will be explained. First, the servo sector information read by the ratator head 22 from the servo sector II of the magnetic disk 10 is amplified by the head amplifier 23, and is then amplified by the head amplifier 23.
(embedded bit by bit) is read into the gate array 24 in asynchronous synchronization. Thereby, the DSP 15 reads the Gray code register provided inside the gate array 24, and converts it to a cylinder position based on the reading result. Further, the DSP 15 calculates the moving speed of the head from the current head position and the past head position. In this case, the head positioning control is performed by the DSP 15 at the OD
DEVEN! This is performed by digital servo control based on the detailed position of the head within the track read from IJ 712. Note that in order to improve positioning accuracy and disturbance resistance, it is desirable to increase the loop gain of the sector servo system as much as possible. On the other hand, the detection signal corresponding to the acceleration of the cow Yarrow detected by the acceleration pickup 21 (see FIG. 5) is
It is supplied to the analog input pin AN3 of P15. In this case, as shown in FIG.
ec), and the servo sector information is sampled every other sector. And analog input bin AN3 of DSP15
The acceleration signal supplied to the sensor is passed through an anti-aliasing filter 3°, subjected to time integration twice, and then passed through a bypass filter 31. Further, the position signal detected by the detector 25 (see FIG. 6) is supplied to the analog input pin ANI of the DSP 15, and then passed through the anti-aliasing filter 33. Then, both the signals are added and combined to form a reliable position feedback signal up to ω=π/T s (red/s). After this, the position feedback signal is finally supplied to the VCM driver 19, and the VCM driver 19
Head positioning control is performed by driving and controlling the head. According to this embodiment, the loop gain of the servo system can be increased by shortening the sampling time to the processing capacity limit of the DSP 15 while keeping the number of servo sectors the same as in the prior art. In other words, the frequency of the position reproduction signal can be adjusted to N·π/Ts (N = 1.2, 3...
), and the control characteristics of the servo system can be improved in proportion to this. As a result, positioning accuracy and disturbance resistance can be improved, and by increasing the loop gain, settling time and access time can be shortened. In this embodiment, the acceleration signal detected by the acceleration pickup 21 is used because it is easy to detect the acceleration of the carriage.In this case, if the position is X, then at d'X/dt'' n (0, l, 2
．． ) is larger, the easier the detection is.

【Effect of the invention】

As described above, according to the present invention, in a magnetic disk device to which a sector servo control method is applied, a head drive means for controlling drive of a magnetic head based on position feedback information, and a head support member for supporting the magnetic head are provided. an acceleration detection means for detecting the acceleration of the head support member; a position detection means for detecting the position of the magnetic head based on servo sector information written in a servo sector; and a position of the magnetic head detected by the position detection means. Since the configuration includes a control means for supplying position feedback information obtained by combining information and acceleration information of the head support member detected by the acceleration detection means to the head drive means, the following effects can be achieved. . (2) Improved servo control characteristics can be achieved without being restricted by the interface of the magnetic disk drive or reducing the data area due to an increase in the number of servo sectors. ■The above ■ makes it possible to improve the positioning accuracy of the magnetic head, that is, the tracking performance and resistance to disturbance forces.
Furthermore, settling time and access time can be shortened.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a magnetic disk according to an embodiment of the present invention, Fig. 2 is a conceptual diagram of a servo sector of this embodiment, Fig. 3 is a program diagram of a servo control system of this embodiment, and Fig. 4 is a diagram showing the internal configuration of the DSP of this embodiment, FIGS. 5 and 6 are waveform diagrams of signals input to the DSP of this embodiment, and FIG.
') is a conventional zero-order hold circuit, Figure 7(b) is an output waveform diagram of the conventional zero-order hold circuit, Figure 8 is a characteristic diagram showing aliasing errors, and Figure 9 is the internal configuration of a conventional DSP. FIG. 10... Magnetic disk, 11... Servo sector, 15... DSP (control means), 19.
...VCM driver (head driving means), 21.
...acceleration pick-up (acceleration detection means),
22...Data head (magnetic head), 25.
...Detector (position detection means).

Claims (1)

[Claims] In a magnetic disk device employing a sector servo control method, a head drive means for controlling drive of a magnetic head based on position feedback information, and an acceleration means disposed on a head support member supporting the magnetic head for detecting acceleration of the head support member. a detection means, a position detection means for detecting the position of the magnetic head based on servo sector information written in a servo sector, and position information of the magnetic head detected by the position detection means and the head detected by the acceleration detection means. A magnetic disk drive characterized by comprising: control means for supplying position feedback information combined with acceleration information of a supporting member to the head driving means.