JPH04170776A - Information storage device and its control method and control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information storage device, particularly a servo system for a fixed magnetic disk device, and a control device thereof.

[Conventional technology]

An overview of conventional fixed disks is shown, for example, in ``Latest Magnetic Recording Technology, Apparatus, and Apparatus'' (Sogo Gijutsu Publishing), p. 5. An outline of the servo system is shown in "Hard Disk Device and Controller" (Interface, May 1984 P2O3). Magnetic head alignment of fixed magnetic disks such as hard disk drives is an extremely important technique for improving disk storage density and access time.

The fixed disk head is usually controlled by a servo mechanism as shown in FIG. 2(a). Here, a conventional example will be described using a servo surface servo in which position information (servo pattern) is written on a dedicated disk surface.

The outline of the seek operation is as follows. Seeking means moving the head to a target track.

In response to data write and read requests from the host computer, the track difference between the current head position and the target position is set in a difference counter via the disk controller. Furthermore, a target speed for moving the head is determined in accordance with this track difference. On the other hand, when the head starts moving, the head position is detected by demodulating the signal from the disk surface on which the servo pattern has been written. The head speed is determined by differentiating this head position. The head speed can also be determined by integrating the current that drives the VCM (voice coil motor). The drive of the motor is controlled so that the head speed obtained in this way is equal to the target speed. Next, the following operation is as follows. The position error signal obtained from the servo head is demodulated and the motor is controlled so that the signal becomes zero. The phase compensation shown in FIG. 2(a) serves to stabilize the servo system. 2nd order low pass filter (
The LPF functions to attenuate high frequencies, and the notch filter functions to attenuate resonance frequencies of mechanical systems such as arms. Further, the external force correction is to correct an external force such as a spring force. Now, the single servo system controls the mechanical system of the head. Mechanical systems vary from product to product, so adjustments must be made for each product for highly accurate control. For example, it is necessary to use the circuit shown in FIG. 2(b) as a notch filter to prevent resonance of the arm, and adjust the resonance frequency by adjusting the resistor R.

Conventionally, such work was done manually.

Alternatively, it was omitted at the expense of accuracy. Further, correction values for external forces such as spring force are stored in the controller of the disk shown in FIG. 2(a), and are adjusted for each product using a variable resistor or the like.

[Problem to be solved by the invention]

As can be seen from the example mentioned above, in the conventional control method,
Not only was the adjustment complicated, but it was also impossible to respond to changes in the mechanical system over time, making highly accurate control impossible.

An object of the invention is to provide a control method that simplifies the adjustment of machine variations.

Another object of the invention is to provide a method for correcting variations in electrical circuits.

Another object of the present invention is to update the information necessary for the above control and to enable highly accurate control.

Another object of the present invention is to perform the above control reliably to prevent the device from running out of control.

[Means to solve the problem]

In order to achieve the above object, control information for adjusting the mechanical system and electric circuit system is stored in the storage device itself, and this information is read out and controlled at startup.

Furthermore, the control information is updated by learning, and the updated control information is stored in the storage device as appropriate.

Furthermore, in order to reliably read out the control information, the control information is stored in a plurality of locations, and a reference signal is read prior to reading out the control information to confirm that the readout operation is normal.

[Effect]

The storage medium of the storage device has the ability to store specific control information for adjusting or correcting the mechanical or electrical system of the storage device. Further, this control information is read out at startup, transferred to a memory circuit or register, and used to control the storage device.

This eliminates the need for adjustment using variable resistors.

Furthermore, the above control information can be stored without using a semiconductor nonvolatile memory.

〔Example〕

A first embodiment of the present invention will be described below with reference to FIG.

This embodiment relates to a disk device and a control method thereof.

The operation of this embodiment is as follows.

When a write or read command is received from the host computer, the microprocessor determines the number of tracks to be moved and outputs a target head speed corresponding to the number of tracks. When the head begins to move, the position is determined by demodulating the signal from the servo disk. By differentiating this, the current head speed is calculated. Head speed can also be calculated by integrating the current flowing through the motor. By controlling the motor with a signal representing the difference between the target speed and the current head speed, the head speed becomes equal to the target speed.

Next, control is entered to follow on the target track.

The position error signal read from the servo head is demodulated and the motor is controlled so that this signal becomes zero. The phase compensation shown in FIG. 1(a) stabilizes the servo system, the secondary low-pass filter (LPF) attenuates high frequencies, and the notch filter attenuates the resonance frequency of the mechanical system such as the arm. Now,
In order to correct variations in the mechanical and electrical systems, in this embodiment, control information is stored on the disk surface containing the data. This information is transferred to the microprocessor via a data regeneration amplifier. FIG. 1(a) shows the case where the data is further transferred to registers 1 and 2.
It may also be stored in a memory portion within the microprocessor. In this embodiment, the information in register 1 controls the notch filter.

The notch filter is constructed as shown in FIG. 1(b), and its resistance value is made variable by controlling switches S to S4. However, the number of switches and resistance values is arbitrary. This allows the frequency of the notch filter to be made variable. Therefore, even if the resonance frequencies of the arms and the like vary from disk device to disk device, the notch frequencies can be matched. Further, it is also possible to correct variations in the notch frequency due to variations in the resistance values and capacitance values constituting the notch filter shown in FIG. 1(b). Although it is generally difficult to correct element constants within an integrated circuit, this embodiment makes it possible. Further, the register 2 shown in FIG. 1(a) stores information for correcting external forces, and corrects external forces that differ from disk drive to disk drive.

As described above, according to this embodiment, variations in the resonance frequency of the arm can be corrected, and the following accuracy can be improved.

Further, it is possible to correct frequency variations caused by notch filters, etc., and improve following accuracy. Further, variations in external force can be corrected, and the amount of offset can be reduced. Figure 1 (
c) shows the flow of control in this embodiment. Initially, when the disk device is started up, control information is read from the disk surface, transferred to the servo system register or memory, and enters the timing state.

A second embodiment of the present invention will be explained with reference to FIG.

This embodiment relates to a disk device and its control method. In this embodiment, the servo corresponding to FIG. 1 is realized by a disk circuit. As shown in FIG. 3(a), control information is stored in a data disk, read out, and transferred to memory via a servo controller. Of course, the memory may be located within the servo controller.

Using this information, the coefficients of the digital notch fill are set and adjusted to the resonant frequency of each device. Furthermore, external force correction can be performed for each device. FIG. 3(b) shows the flow of control in this embodiment.

The basic flow is the same as the first embodiment.

A third embodiment of the present invention will be explained with reference to FIG.

This embodiment relates to a disk control device. Figure 4 (,
) is a disk digital servo device, which includes the filter shown in FIG. 3(a), an AD converter, a servo controller,
Corresponds to the memory and DA converter parts. In this example,
Servo control information read from the disk surface is input via the disk controller. This information is input from the interface circuit and stored in the control information register. This information controls the filter, AD converter, servo processing system, and DA converter. Figure 4(b) to (f)
) is an example of controlling these parts.

FIG. 4(b) is an example of control of the filter circuit.

This circuit is a Sallen-Key type low-pass filter.

The frequency characteristics can be varied by changing the resistance value. Therefore, it is possible to obtain desired filter characteristics by controlling the switch and changing the resistance value using control information. When there are many switches to be controlled, the number of bits of control information can be reduced by controlling them via a decoder. FIG. 4(c) is a circuit similar to that shown in FIG. 4(b), but in this example, the capacitance is changed to make the filter characteristics variable.

FIG. 4 (cl) shows a differential amplifier. This is shown in the same figure (b
), (c) are used in the operational amplifiers and AD converters in the circuits. In this example, the load transistors are switched based on control information. This makes it possible to adjust variations in offset and the like. FIG. 4(e) shows a differential amplifier. In this example, the bias current value is changed based on the control information. FIG. 4(f) shows the servo arithmetic processing section. This part consists of phase compensation as shown in Figure 1(a),
It performs filter processing such as secondary LPF and notch filter, and calculates target speed and external force correction values. Control information is input from the input/output port and stored in memory. Based on this information, the coefficients for the above filter calculation are set. Also, based on this information, the external force correction value is determined. Furthermore, control information can also be input to the data bus control circuit as required. This allows the processing contents themselves to be made variable. For example, by increasing the calculation routine of the notch filter, it becomes possible to attenuate multiple resonance frequencies. In this way, the same disk servo device can be used with various disk models.

A fourth embodiment of the present invention will be explained with reference to FIG.

In this embodiment, the present invention is applied to a data surface servo disk device. Data surface servo is a method in which servo patterns are not recorded on a dedicated disk surface, but are recorded on a predetermined location on the disk surface where data is to be recorded. Therefore, in this device, the servo pattern is read out by the data head. After this signal is amplified by a read amplifier, it is separated from data and input to a demodulation circuit.

In this embodiment, control information such as correction of variations in the mechanical system and electric circuit system is recorded on a data disk, and is read out and controlled by the disk controller.

Transfer to memory via servo controller.

Of course, the memory may be located within the servo controller. The effects of this embodiment are the same as those of the second embodiment.

A fifth embodiment of this embodiment will be explained with reference to FIG. This embodiment relates to a method of updating control information for a disk servo. Reading control information when starting the disk is as follows:
This is the same as the second embodiment.

In this embodiment, servo control information is updated during disk operation. For example, if the disk surface is eccentric, the trajectory of the disk's tracks will deviate from a circle. Therefore, in order to cause the disc to follow on the track, a periodic control signal determined by the rotational frequency of the disc is output. By utilizing this periodicity, it becomes possible to predict the control signal of the next period after a certain period, and it is possible to improve the following accuracy. Information necessary for such control is stored in the memory of the servo system, and this information is updated depending on the degree of eccentricity. Another example is updating information on external force correction such as spring force. These correction amounts change as the disc ages. Therefore, by updating this correction amount, deterioration of the offset amount can be avoided even if there is a change over time. Another example is compensation for thermal expansion due to temperature changes. In a servo surface servo system, there is a problem of so-called thermal off-track, in which the data surface does not accurately follow the track even if it is followed on the servo surface due to the difference in thermal expansion between the servo surface and the data surface. Therefore, the temperature or off-track amount is measured at predetermined intervals, and information necessary for correction thereof is updated. As described above, a highly accurate servo system is realized by updating the control information read at the time of disk startup. In this embodiment, updated control information is written to the disk when the operation of the disk is stopped. As a result, the updated control information is read out the next time the servo system is started, so a stable servo system can be obtained quickly. however,
The next time it is started, the disk has cooled down and the previously updated control information for thermal off-track correction is not available. Therefore, such control information does not need to be saved when the disk is stopped.

A sixth embodiment of the present invention will be described with reference to FIG.

This embodiment relates to a method of updating control information for a disk servo. The reading of control information at the time of disk startup is the same as in the second embodiment or the fifth embodiment. Furthermore, in this embodiment as well, the control information in the servo system memory is updated in the same manner as in the fifth embodiment. This embodiment relates to a method of writing updated control information to a disk when the operation of the disk is stopped. In this embodiment, control information is additionally recorded. This makes it possible to leave a history of control information. By using the information left in this way, the disk servo system can be self-diagnosed. For example, by analyzing the aging of mechanical systems,
You can know when the next disk maintenance is required. Furthermore, even if incorrect control information is recorded due to some malfunction, the disk can be started by reproducing previously recorded control information. Alternatively, it is also possible to use the average value of previously recorded control information when starting the disk. It goes without saying that the history of the control information as described above may be left for a desired number of times, and the control information prior to that number of times may be deleted.

A seventh embodiment of the present invention will be described with reference to FIG.

This example is based on the 6th. The present invention relates to a method of updating servo control information as in the seventh embodiment. In FIG. 8, the input signal of the notch filter shown in FIG. 1(a) is frequency analyzed, and the control information of the notch filter is updated based on the result. The frequency analysis determines the resonant frequency, that is, the frequency that should be attenuated by the notch filter. The control information stored in the register 1 is updated to match the zero point of the notch filter to this frequency. In this way, an optimal notch filter can be provided for each individual disk drive. It goes without saying that this embodiment can be used in parallel with the embodiments shown in FIGS. 3 to 5. In addition, the input signal of the notch filter is taken out to the outside of the disk device via the disk controller, and
For example, frequency analysis may be performed by a host computer.

An eighth embodiment of the present invention will be described with reference to FIG.

This embodiment relates to a method for protecting control information for a disk servo. That is, this is a method of preventing disk servo control information from being erased by the disk user. When receiving a data write or disk initialization command from the host computer, it is determined whether or not the above control information is destroyed, and only when the control information is not destroyed, control is performed to write or initialize the data. . That is, in this embodiment, control information is stored in an area that is not open to disk users.

〔Effect of the invention〕

According to the present invention, variations in the mechanical system or electric circuit system of the disk servo and changes over time are corrected, so it is possible to reduce resonance in the arm system and reduce the amount of offset during following. Furthermore, deterioration in following accuracy due to eccentricity and thermal off-track can be avoided.

[Brief explanation of the drawing]

Fig. 1 shows a first embodiment of the present invention, Fig. 2 shows a conventional technique, Fig. 3 shows a second embodiment of the invention, and Fig. 4 shows a diagram of a conventional technique. FIG. 5 is a diagram showing the fourth embodiment of the present invention. FIG. 6 is a diagram showing the fifth embodiment of the present invention.
FIG. 7 is a diagram showing a sixth embodiment of the present invention, FIG. 8 is a diagram showing a seventh embodiment of the present invention, and FIG. 9 is a diagram showing the present rod. > 1st agony (su￥J 2 fig. Cb) ′fJ31 (b) 734 fig. Rod 5 Figure % q Figure

Claims (1)

Claims: 1. An information storage device characterized in that a mechanical system of the information storage device is controlled by information read from an information storage area within the information storage device. 2. An information storage device according to claim 1, which controls mechanical movement within a mechanical system using information read from an information storage area. 3. An information storage device according to claim 1, which controls an electric circuit included in a mechanical system using information read from an information storage area. 4. The information storage device according to claim 1, wherein the information read from the information storage area is updated and the updated information is written to the information storage area. 5. The information storage device according to claim 4, wherein updated information is additionally recorded in the information storage area. 6. A method for controlling an information storage device, which comprises frequency-analyzing signals within a mechanical system of the information storage device and controlling the mechanical system based on the result. 7. An information storage device according to claim 1, characterized in that information for controlling a mechanical system is stored in an area that is not open to disk users. 8. A control device characterized in that a signal input from an information storage device is stored in a memory or a register, and the characteristics of an electric circuit are controlled by the signal.