JPH0245261B2 - JIKIDEISUKUSOCHI - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a magnetic disk device having a function of controlling a reference speed in a deceleration control section of a seek operation, which is an operation of positioning a recording/reproducing head to a target position. .

(b) Background of the technology In magnetic disk devices, the mechanism for positioning the recording/reproducing head at the target position generally includes a voice coil type linear motor and a mechanism arranged so that it can freely rotate around a rotation axis. A rotary voice coil motor fixed to a rotary arm has been put into practical use. The seek operation by these mechanisms includes, for example, an acceleration control period in which the voice coil motor is accelerated and a deceleration control period in which the voice coil motor is decelerated.In the acceleration control period, a constant voltage is applied to both ends of the voice coil motor. Speed control uses a voltage method, and in the deceleration control section, a target speed is given according to the difference between the current position and the position (distance) to the target position, and current is applied to the voice coil motor according to the difference between the current speed and the target speed. method is adopted.

With the above control method, it is necessary to position the recording/playback head to the target position at high speed and with high precision. However, the mechanism using a voice coil motor has certain limitations, and a higher There is a need to develop a method for positioning at high speed and with high precision.

(c) Prior Art and Problems A conventional control method in a deceleration control section of a seek operation in a magnetic disk device will be explained with reference to the drawings.

FIG. 1 shows a conventional control method for a seek operation, in which A shows a circuit block diagram and B shows a characteristic diagram.

In the figure, 1 indicates a reference speed generation circuit, and 2 indicates a speed error detection circuit.

In addition, ~ indicates the symbol at each position in Fig. 1A, where is the target speed, is the actual speed, is the speed error, is the difference in distance to the target point, is the deceleration control section signal, and is the voice coil motor (Fig. (not shown).

Figure 1 shows the reference speed generation circuit 1 and related circuits that set the target speed in the deceleration control section of the seek operation.The difference in distance to the target point shown in Figure 1B is input to the reference speed generation circuit 1. Then, the target speed is determined by the speed error detection circuit 2.
is output to. Note that the difference in distance to the target point is determined and input before the acceleration control section control, and the target speed is output by the reference speed generation circuit 1 even in the acceleration control section, but this target speed is only for reference, and the actual It is controlled by another control circuit not shown.

On the other hand, the actual speed is also input to the speed error detection circuit 2. The speed error detection circuit 2 outputs the difference between the actual speed and the target speed, that is, the speed error.
A current corresponding to this speed error flows to a voice coil motor (not shown) to control the actual speed. Conventionally, the trend has been to shorten the access time (the time required to go from the current point to the target point) in order to complete the seek operation in a short time. The deceleration control section has been shortened.

On the other hand, if the difference in distance to the target point is large, the deceleration current flowing through the voice coil motor (not shown) will also increase; There are certain limits to the current that can flow through the That is, the deceleration current is Id, the voltage applied across the voice coil motor (not shown) is Vc, the induced voltage proportional to the speed of the voice coil motor (not shown) is Vi, and the voice coil motor (not shown) is the induced voltage proportional to the speed of the voice coil motor (not shown). (Not)
If the coil resistance of is Rc, then the deceleration current Id≦Vc+
There is a relationship of Vi/Rc, and the speed error signal is Vc+
Even if a current larger than Vi/Rc is required, Vc+Vi/
The drawback was that the current only flowed up to Rc, resulting in a clamped state and uncontrollability.

Note that such a state occurs when the difference in distance to the target point is larger than a predetermined value, and does not occur when the difference in distance to the target point is greater than a predetermined value. That is, there is a characteristic that if the current is within Vc+Vi/Rc, it will not occur.

(d) Purpose of the Invention An object of the present invention is to provide a new magnetic disk device that eliminates the above-mentioned drawbacks, and in particular, even if the difference in distance to the target point of the seek operation is more than a predetermined value, the voice coil The object of the present invention is to realize a magnetic disk device that can always control the current flowing through a motor to be below the saturation current and perform stable seek operations.

(e) Structure of the Invention The present invention divides and controls a seek operation, which is an operation for positioning a recording/reproducing head to a target position, into an acceleration control section and a deceleration control section, and generates a reference speed for the deceleration control section. and a speed error detection circuit that compares the reference speed with the actual speed and generates a speed error signal, the magnetic disk device starts operating at the same time as the start of the acceleration control section. By providing means for outputting a predetermined signal at the same time as the deceleration control section and canceling the output of the predetermined signal at the same time as the start of the deceleration control section, and adding the output of the means to the reference speed generation circuit to displace the reference speed, This can be achieved by a magnetic disk device characterized in that the deceleration current flowing through the seek operation mechanism is always controlled to be below the saturation current, thereby making it possible to perform stable seek operations.

(f) Examples of the invention The present invention will be explained below with reference to the drawings.

FIG. 2 shows a seek operation control method according to the present invention, in which A shows a circuit block diagram and B shows a characteristic diagram.

In the figure, 3 indicates a deceleration control section detection circuit, 4 an offset generation circuit, 5 a determination circuit, 6 a power amplifier, and 7 a voice coil motor (hereinafter abbreviated as VCM).

Note that the same symbols as in FIG. 1 indicate the same contents or indicate offset signals.

In this embodiment, during a seek operation, a reference speed generation circuit 1 inputs the difference in distance from the current point to the target point to set the target speed to the target point, and outputs a speed error based on the difference between the target speed and the actual speed. The speed error detection circuit 2 detects entry into the deceleration control period based on the target speed and actual speed and outputs the deceleration control period signal. An offset generation circuit 4 outputs a signal that slightly moves up and down and displaces the apparent characteristics to the reference speed generation circuit 1, and cancels the output of the offset signal according to the deceleration control section signal, and the difference in distance to the target point is set to a predetermined value. If it is larger, a determination circuit 5 outputs a signal to the offset generation circuit 4, a power amplifier 6 amplifies the speed error value and sends a drive current corresponding to the speed error value to the VCM 7, and a recording/reproduction head (Fig. (not shown) to the target position.

Next, the operation of this embodiment will be explained. Note that the target speed output from the reference speed generation circuit 1 during the acceleration control section is a reference speed, and the acceleration control is controlled by another circuit not shown.

A seek operation is started based on the difference in distance from the host device (not shown) to the target position, resulting in acceleration control. At this point, the determination circuit 5 determines whether the difference in distance to the target position is greater than a predetermined distance, and if it is greater than the predetermined distance, outputs an output signal to the offset generation circuit 4. The offset generation circuit 4 starts operating upon receiving the signal from the determination circuit 5, and outputs an offset signal to the reference speed generation circuit 1. The offset signal is a signal for controlling the displacement of the target speed curve so that the difference in distance between the target speed output from the reference speed generating circuit 1 and the apparent target position is smaller than a predetermined value. Note that the portion indicated by the dotted line in FIG. 2B shows the target speed curve that is not controlled by the offset signal.

When entering the deceleration control section, the deceleration section detection circuit 3
A signal is output to the offset generation circuit 4, which cancels the output of the offset signal, and controls the current flowing through the VCM 7 accurately using the speed error obtained between the target speed controlled by the offset signal and the actual speed. And quickly record to the target point/
Position the playback head (not shown).

(g) Effects of the Invention According to the present invention as described above, even if the difference in distance to the target is greater than a predetermined value, the current flowing through the voice coil motor is always controlled to be below the saturation current, and stable seek operation is possible. This has the advantage that it is possible to provide a magnetic disk device with a high level of performance.

[Brief explanation of the drawing]

FIG. 1 shows a conventional method for controlling a seek operation, and FIG. 2 shows a method for controlling a seek operation according to the present invention. In the figure, 1 is a reference speed generation circuit, 2 is a speed error detection circuit, 3 is a deceleration control section detection circuit, 4 is an offset generation circuit, 5 is a determination circuit, 6 is a power amplifier, and 7 is a VCM.

Claims (1)

[Claims] 1. A reference speed generation circuit that divides and controls a seek operation, which is an operation for positioning a recording/playback head to a target position, into an acceleration control section and a deceleration control section, and generates a reference speed for the deceleration control section; A magnetic disk device comprising a speed error detection circuit that compares speed and actual speed and generates a speed error signal, which starts operation at the same time as the start of the acceleration control section and outputs a predetermined signal to detect the deceleration. A magnetic disk device characterized in that means is provided for canceling the output of the predetermined signal at the same time as the start of a control section, and the output of the means is added to the reference speed generation circuit to displace the reference speed.