JPH0240176A - Disk device - Google Patents

Abstract

PURPOSE:To improve the speed control characteristics for a head by providing a filter for smoothing an output of a target speed generator between the target speed generator and a subtractor. CONSTITUTION:The filter 13 for smoothing the output of the target speed generator 9 is additionally provided between the target speed generator 9 and the subtractor 10. A signal of a target speed outputted from the target speed generator 9 is smoothened in its step-like waveform by passing through the filter 13, and this signal and a signal from a speed detector 4 are inputted to the subtractor 10, where their difference is calculated to be inputted to a drive circuit 12. Then, an actuator 11 is driven by a drive current outputted from this drive circuit 12, and this drive current is suppressed enough in its ripple part. By this method, the speed suppression characteristics and accuracy of the magnetic head are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disk device such as a magnetic disk device for recording and reproducing information, and particularly relates to a head speed control method thereof.

[Conventional technology]

FIG. 3 is a block diagram showing a head speed control method in a conventional magnetic disk device of this kind disclosed, for example, in Japanese Patent Application Laid-Open No. 62-262283. In the figure, (1
) is a disk-shaped magnetic disk on which many recording tracks are concentrically formed as an information recording medium, and (2) is a disk-shaped magnetic disk that serves as an information recording medium. (3) is a position detector that detects the position of magnetic head (2); (4) is a position detector that detects the speed of magnetic head (2) based on the output of position detector (3). A speed detector (51) outputs a speed voltage signal corresponding to A track passing detector that outputs pulses, (6) is a track passing detector (
(5) timing means for timing the interval of pulses from (7);
is a CPU, (8) is a D/A converter that converts the digital output from the CPU (71) into an analog voltage signal, and a track passage detector (51, a clock means (6),
U (2) and the D/A converter (8) constitute a target speed generator (9) that generates a target speed voltage signal V0. θO) is the speed detector (a) and target speed generator (9)
(II) is an actuator that moves the magnetic head (2) between each recording track, and (12) is an actuator that moves the magnetic head (2) between each recording track according to the output of the subtractor α0). ) is a power amplifier that serves as a drive circuit that supplies drive current to the Next, the operation will be explained.

A magnetic head (2) reads position information recorded on a recording track of a magnetic disk (1), and a position detector (3) performs position detection based on this information. The speed detector (a) differentiates the output of the position detector (3) to detect the magnetic head (
2) Detects the actual speed and outputs the speed voltage signal ■.

On the other hand, each time the CPU (71) receives one output pulse from the track passage detector (51), it calculates the number of remaining recording tracks by 1 to the target recording track that the magnetic head (2) should reach.
The target speed voltage signal corresponding to the number of remaining recording tracks is read out from the ROM. In this case, the actual time of the pulse interval of the track passage detector (5) is detected by the timer (6), the target speed voltage signal is corrected based on this, and the output is sent to the D/A converter. (8), and outputs the target speed voltage signal V as an analog value.The subtracter (101) calculates the difference d between the two pressure signals V, V, and sends it to the power amplifier (12). The actuator (11) is driven by the drive current amplified here,
A series of head speed controls are performed.

[Problem to be solved by the invention]

Since the conventional magnetic disk drive is configured as described above, the output of the target speed generator (9) and therefore the output of the D/A converter (8) becomes a step voltage signal, so the following A problem arises.

That is, although FIG. 4 shows the waveforms of the voltage signals V 1 , Vo , and ■1, both type pressure signals ■. , ■ A fairly steep ripple occurs in the voltage signal ■4, which is the difference between the voltage signals ■ and ■. As a result, the drive current supplied to the actuator (11) also contains ripples, which deteriorates the speed control accuracy of the magnetic head (2). This characteristic becomes an important problem when stopping at a target recording track. This ripple also becomes a factor in noise generation.

Here, in order to reduce the ripples mentioned above, a method may be considered in which each step voltage is controlled more finely. but,
In this case, it is necessary to further speed up the functions of the digital processing device such as the CPU (7), making the device complicated and expensive.

This invention was made in order to solve the above-mentioned problems, and its purpose is to provide a disk device in which the conventional target speed generator can be used as is and the influence of ripple can be sufficiently suppressed. do.

[Means to solve the problem]

The disk device according to the present invention further includes a filter for smoothing the output of the two-north exit speed generator between the target speed generator and the subtractor.

[For production]

The step-like waveform of the target speed signal output from the target speed generator is smoothed by passing through a filter, and this signal and the signal from the speed detector are input to a subtracter, and the difference is calculated. and input to the drive circuit.

The actuator is driven by the drive current output from this drive circuit, and since the ripple component of the drive current is sufficiently suppressed, the speed control characteristics and accuracy of the magnetic head are improved.

〔Example〕

FIG. 1 is a block diagram showing a head speed control method for a magnetic disk device in an embodiment of the present invention. In the figure, the difference from the conventional case in Figure 3 is that the filter is a low-pass filter (hereinafter referred to as LPF).
The only difference is that 3) has been added. That is, L P F (
13) is the D/A converter (8) of the target speed generator (9).
) and the subtractor α0), and smoothes the step-like waveform of the target speed voltage signal o from the D/A converter (8) and sends it to the subtractor α0).

Next is the operation, which is almost the same as the conventional one, so a detailed explanation will be omitted. However, the target speed voltage signal V output from the D/A converter (8). As shown in Figure 2,
Target speed voltage signal ■ smoothed by L P F (13). It becomes 6. The subtracter 00) is this LP F (1
3) Target speed voltage signal from ■. 8 and speed detector (a)
The power amplifier (
12) Outputs the voltage signal ■. Here, the target speed voltage signal V. As a result of the waveform of S being considerably smoothed from the conventional completely step-like waveform, as can be seen from FIG. The pulsation component is reduced compared to the two-type pressure signal V. As shown in the figure, the difference V and r between s and ■ has no steep peak at all, and the ripple component is suppressed to an extremely low level.

As a result, the actuator (
11), the ripple component of the drive current supplied to the magnetic head (2) is also sufficiently reduced, the speed control characteristics of the magnetic head (2) are improved, and characteristics with sufficiently high accuracy can be expected even during particularly important deceleration control.

Furthermore, the noise value also decreases due to the reduction in ripple components. In addition, in the above embodiment, L P F is used as a filter.
(13) was used, but the step-like target speed voltage signal ■. If it smooths out the individual circuit conditions,
It can also be constructed from various circuit elements depending on the constants.

Further, the present invention is not limited to magnetic disk devices, but can be similarly applied to other disk devices such as optical disk devices.

〔Effect of the invention〕

As described above, in this invention, a filter is added between the target speed generator and the subtractor to smooth the output of the target speed generator, so that the smoothed output and the output of the speed detector are The ripple component of the drive input supplied to the actuator is suppressed in accordance with the difference between the two, improving head speed control characteristics and reducing noise based on the ripple component.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the head speed control method of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the waveforms of each voltage signal, and FIG. A block diagram showing the speed control method, and FIG. 4 is a characteristic diagram showing the waveforms of each voltage signal in the case of FIG. 3. In the figure, (1) is the magnetic disk, (2) is the magnetic head, (width is the speed detector, (9) is the target speed generator, (width) is the subtractor, (11) is the actuator, and (12) is the power amplifier. , (13) is a low-pass filter as a filter. Note that the same reference numerals in each figure indicate the same or corresponding parts. Field

Claims (1)

[Claims] A disk on which a plurality of recording tracks are formed, a head for writing or reading information on the recording tracks, an actuator for moving the head between the respective recording tracks, a speed detector for detecting the moving speed of the head, and the head. a target speed generator that generates a step-like target speed to be commanded; a subtracter that calculates the difference between the outputs of this target speed generator and the speed detector; and a subtracter that operates the actuator in accordance with the output of this subtracter. What is claimed is: 1. A disk device comprising a drive circuit for driving the disk device, characterized in that a filter is provided between the target speed generator and the subtracter to smooth the output of the target speed generator.