JPS6145301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positioning control device for a magnetic head, and more particularly, to a positioning control device for a magnetic head, and in particular to a magnetic head positioning control device that uses positional information discretely written on each track of a data surface of a magnetic disk and a speed signal of an actuator for moving a magnetic head. The present invention relates to a positioning control device that demodulates a position signal based on the following.

According to the conventional magnetic head positioning control device system, a position signal written in the center of each track on a dedicated disk surface is read by a servo magnetic head to obtain a position signal, and based on this position signal, multiple data The entire position of the cart (actuator or carriage) to which the magnetic head was attached was determined. However, in recent years, as the recording density of magnetic disks has increased, the width of the data track has become narrower to 25 to 60 microns. The relative positional deviation between the head and the data head has become a value that cannot be ignored.

As a method for correcting such positional deviations, positional information is discretely written on the data surface of each of a plurality of magnetic disks included in a magnetic disk drive, and this positional information is written for each disk by the data head corresponding to the disk. A method has been proposed in which a position signal is obtained by reading the data, and the data head is accurately positioned on a desired data track based on the position signal. The data surface of a magnetic disk using this method is shown in FIG. In FIG. 1, position information writing areas 2 are provided radially and discretely on a magnetic disk 1. As shown in FIG. In order to achieve a sufficiently satisfactory positioning accuracy of the magnetic head, it is necessary to write a certain number of pieces of position information per revolution of the disk. However, as the number of positional information increases, the area of the area 3 in which data is recorded decreases accordingly. Therefore, there is a need to increase the positioning accuracy of the magnetic head and to reduce the amount of position information.

An object of the present invention is to obtain a low frequency component of a position signal from position information on a disk read by a magnetic head, and to obtain a low frequency component of a position signal detected by a speed detector attached to a carriage. Based on the concept of obtaining high-frequency components of position signals from velocity signals, we have developed a system that enables magnetic head positioning control devices to obtain broadband position signals based on a relatively small amount of position information written on magnetic disks. Therefore, it is possible to expand the data recording area of the magnetic disk without reducing the positioning accuracy of the magnetic head.

The magnetic head positioning control device provided in the present invention includes at least one magnetic head provided facing a recording medium on which position information is discretely written on each of a plurality of concentric tracks;
An actuator for moving the magnetic head to a desired track position on the recording medium based on position information read by one of the magnetic heads, and a speed detector for detecting the speed of the actuator. A first-order delay circuit is added to receive a composite signal of the position information read by the magnetic head and the speed signal obtained by the speed detector, thereby demodulating the broadband position signal. It is characterized by

An embodiment of the magnetic head positioning control device according to the present invention will be described with reference to FIGS. 2 to 4. FIG.

FIG. 2 is a diagram showing a data surface of a magnetic disk to which the present invention is applied. In FIG. 2, it can be seen that the area of the position information writing areas 5 provided radially and discretely is smaller than that in FIG. 1. If an attempt is made to obtain a position signal from discrete position information written in such a small area, a highly accurate position signal cannot be obtained because the frequency components contributing to the formation of the position signal are low frequencies. A magnetic head positioning control device according to an embodiment of the present invention for solving this problem is shown in FIG. In FIG. 3, discrete position information of the magnetic disk 10 is transmitted to the magnetic head 1.
1 and then input to the sample and hold circuit 12 as a pulse. In the sample and hold circuit 12, the discrete pulse signal is converted into an analog signal. Since the amount of position information written on the disk is relatively small, the frequency of the pulse signal obtained by reading it is relatively low, and therefore the analog signal obtained based on this pulse signal is not necessarily accurate as a position signal. isn't it. In order to compensate for this, in the present invention, the speed of the magnetic head 11 is detected by a speed detector 14 attached to an actuator (head actuator) 13 for moving the magnetic head 11 over the magnetic disk 10. It takes advantage of speed. That is, utilizing the fact that the integral value of the speed signal obtained by the speed detector 14 represents a high frequency component of the position signal, the gain of the speed signal obtained from the speed detector 14 is adjusted in the coefficient unit 17, while the sample and hold circuit 12
The position signal obtained at the output of
The added signal obtained at the output of 8 is then input to a first-order delay circuit 19. The first-order delay circuit 19 is essentially an integrating circuit, and its time constant T is T=Av/Ax, where Ax is the position gain of the position signal coefficient multiplier 16 and Av is the speed gain of the speed signal coefficient multiplier 17. It is set to satisfy the following relationship. With this setting, the high frequency component of the addition signal inputted from the adder 18 is appropriately integrated, and therefore, the low frequency component of the position signal and the speed signal are output to the output of the first-order delay circuit 19. An equivalent position signal is obtained by combining the integrated position signal and the high frequency component.

In this way, the high frequency component of the position signal is compensated by the speed signal from the speed detector, so that even if the number of position information on the disk is small and the sampling frequency is low, a broadband position signal can be synthesized.

The position signal obtained at the output of the first-order delay circuit 19 is sent to the controller 20 and the power amplifier 21 as in the conventional case.
via the head actuator 13, thereby moving the magnetic head 11 to a desired position.

What is important in the circuit of FIG. 3 is how to select the time constant of the first-order lag filter 19. If the angular frequency at which the open loop gain is 1 in the circuit shown in Figure 3 is ω ₁ , then the time constant T of the filter is 1/
It has been found that a value of ω ₁ to 1/2 ω ₁ is sufficient. In conventional control using only discrete position signals, which does not use the method of the present invention, the frequency of the position signal pulse (which is proportional to the number of position information to be recorded in one rotation of the disk) is required to be approximately _10ω1 . However, according to the embodiment of the present invention, it is reduced to 1/
It becomes possible to reduce the number to about 5.

As is clear from the above description, the present invention enables a positioning control device for a magnetic head to obtain a broadband position signal based on a relatively small amount of position information written on a magnetic disk.
Therefore, it is possible to expand the data recording area of the magnetic disk without reducing the positioning accuracy of the magnetic head.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a data surface of a magnetic disk for explaining a conventional positioning method, FIG. 2 is a diagram showing a data surface of a magnetic disk applied to a positioning device according to the present invention, and FIG. 3 is a diagram showing a data surface of a magnetic disk according to the present invention. 1 is a block circuit diagram of a magnetic head positioning control device according to one embodiment; FIG. 1, 4: Magnetic disk, 2, 5: Position information writing area, 6: Data writing area, 10: Magnetic disk, 11: Magnetic head, 12: Sample and hold circuit, 13: Head actuator, 14: Speed Detector, 16, 17: Coefficient unit, 18: Adder, 1
9: First-order delay circuit.

Claims (1)

[Claims] 1. At least one magnetic head provided facing a recording medium in which position information is discretely written on each of a plurality of concentric tracks, and a position read by one of the magnetic heads. an actuator that moves the magnetic head to a desired track position on the recording medium based on the information; and a speed detector that detects the speed of the actuator; and position information read by the magnetic head. A positioning control device for a magnetic head, characterized in that a first-order delay circuit is added to receive a composite signal of the speed signal obtained by the speed signal and the speed signal obtained by the speed detector, and thereby demodulates a broadband position signal.