JPH01189082A - Magnetic head positioning circuit - Google Patents

Abstract

PURPOSE:To enhance the positioning accuracy of a magnetic head by adding the output of the position error signal generating circuit of a positioning servo circuit and the output of the offset adjusting circuit and driving a voice coil motor. CONSTITUTION:A positioning servo circuit 1 detects a position error from the aimed track of a movable part 6 by means of a position error signal generating circuit 3. An absolute address signal 11 determined by the position of the magnetic head is supplied to the input of a memory circuit 8 in an offset adjusting circuit 2. Information to correct a steady error at the plural magnetic head positions is stored into the memory circuit 8, and the information stored into an absolute address determined by the position of the inputted magnetic head is outputted. The output of the memory circuit 8 generates a direct current voltage through a D/A converter 9, it is inputted to an adder amplifier 4, sets the output of the generating circuit 3 at zero, and the output of the converter 9 drives a voice coil motor 6 through the adder amplifier 4 and a power amplifier 5. In such a way, the positioning accuracy of the magnetic head can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning circuit for a magnetic head of a magnetic disk device.

[Conventional technology]

In magnetic disk drives, a positioning servo circuit having a servo closed loop is used to accurately position a magnetic head on a target track.

The positioning servo circuit drives the movable part so that the output of the position error signal generation circuit, which outputs a position error signal corresponding to the deviation of the magnetic head from the target track, becomes zero. In this case, external forces such as air currents and gravity caused by the rotation of the disk plate, circuit offsets, etc. are applied to the movable part, and the position of the magnetic head is constantly deviated from the target track.

In the conventional magnetic head positioning circuit, in order to eliminate the steady-state error due to external force or circuit offset, the steady-state error of the magnetic spatula V is corrected by applying a constant DC voltage that corrects the offset to the servo closed loop.

[Problem that the invention seeks to solve]

In the conventional magnetic head positioning servo circuit described above, when the external force applied to the movable part or the circuit offset changes greatly depending on the position of the magnetic head, it is not possible to correct the steady-state error of the magnetic head by simply applying a constant DC voltage to the servo loop. There was a drawback that it became difficult to clean.

[Means for solving problems]

The magnetic head positioning circuit of the present invention includes a position error signal generation circuit that outputs a position error signal indicating the deviation of the movable part from a target track, and outputs the output of the position error signal generation circuit through a power amplifier or the like. In a magnetic head positioning servo circuit which is supplied to a voice coil motor and drives the movable part by the voice coil motor to position the magnetic head on an arbitrary track among a plurality of tracks, the magnetic head is supplied from a positioning control logic circuit. a storage circuit that inputs a digital signal indicating the position of the magnetic head and outputs an offset adjustment digital signal corresponding to the position of the magnetic head; a digital-to-analog converter that converts the output of the recording circuit into an analog signal; - It is characterized by comprising an addition amplifier that adds the output of the analog converter and the output of the position error signal generation circuit and inputs the result to the power amplifier.

〔Example〕

Next, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.

In the positioning servo circuit 1, a position error of the movable part 7 from a target track is detected by a position error signal generation circuit 3. The position error signal generation circuit 3 outputs a position error signal 10 corresponding to the position error of the movable part 7 and supplies it to the summing amplifier 4. The output of the summing amplifier 4 is converted by the power amplifier 5 into a current flowing to the voice coil motor 6, and the voice coil motor 6 drives the movable part 7 to move the magnetic head attached to the movable part 7.

In the offset adjustment circuit 2, a digital signal indicating an absolute address determined by the position of the magnetic head from a positioning control logic circuit is inputted to a storage circuit 8, and the storage circuit 8 converts the information stored in the inputted absolute address into a digital signal. Output with .

The output of the memory circuit 8 is input to a digital-to-analog converter 9, and the digital-to-analog converter 9 outputs a voltage corresponding to the output of the memory circuit 8 and applies it to the summing amplifier 4.

The operation of the offset adjustment circuit 2 will be explained below. When the magnetic head is positioned on the target track, an external force is applied to the movable portion 7 due to the airflow and gravity caused by the rotation of the disk plate. Furthermore, there is an offset in the positioning servo circuit 1, and this circuit offset and the steady error of the magnetic head due to the external force are generated in the output of the position error signal generation circuit 3 as a DC voltage.

In addition, since the external force and circuit offset change depending on the position of the magnetic head, even if this offset changes significantly, the offset adjustment circuit 2 adjusts the DC voltage output from the position error signal generation circuit 3 to zero to eliminate the steady-state error of the magnetic head. This is to correct.

In the offset adjustment circuit 2, when the magnetic head is positioned at an arbitrary position, an absolute address signal 11 determined by the position of the magnetic head at this time is supplied from the positioning control logic circuit to the input of the storage circuit 8. The memory circuit 8 stores in advance information for correcting steady-state errors of the magnetic head due to external forces and circuit offsets at a plurality of magnetic head positions, and is stored at an absolute address determined by the input position of the magnetic head. Output information. The output of the memory circuit 8 is passed through the digital-to-analog converter 9 to generate a DC voltage, which is input to the summing amplifier 4 to set the output of the position error signal generating circuit 3 to zero, and converts the output from the digital-to-analog converter 9 to zero. By inputting the signal to the power amplifier via the summing amplifier, the steady-state error of the magnetic head attached to the movable section 7 can be corrected.

〔Effect of the invention〕

As explained above, the present invention stores information for correcting steady-state errors of the magnetic heads due to external forces and circuit offsets corresponding to the positions of a plurality of magnetic heads in a storage circuit, and converts the output of the storage circuit into an analog signal and outputs it. Equipped with a digital/analog converter, the output of the digital/analog converter corresponding to the position of the magnetic head and the output of the position error signal generation circuit are added together by an summing amplifier, and the voice coil motor is driven by the signal. Therefore, even if the external force or circuit offset changes significantly due to a change in the position of the magnetic head, the effects of the external force or circuit offset applied to the magnetic head can be removed, resulting in high precision that improves the positioning accuracy of the magnetic head. This has the advantage that a magnetic disk device of 100% can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magnetic head positioning circuit of the present invention. 1... Positioning servo circuit, 2... Offset adjustment circuit, 3... Position error signal generation circuit, 4... Adding amplifier, 5... ...Power amplifier, 6...Voice coil motor, 7...
...Movable part, 8...Memory circuit, 9...
・Digital/analog converter, 10... Position error signal, 11... Absolute address signal, 12...
...Offset adjustment voltage. Agent Patent Attorney Oto Uchihara

Claims (1)

[Claims] It has a position error signal generation circuit that outputs a position error signal indicating the deviation of the movable part from a target track, and supplies the output of the position error signal generation circuit to a voice coil motor via a power amplifier. In a magnetic head positioning servo circuit that drives the movable part to position the magnetic head on any one of a plurality of tracks, a digital signal indicating the position of the magnetic head is input and an offset corresponding to the position of the magnetic head is input. A storage circuit that outputs an adjustment digital signal, a digital-analog converter that converts the output of the storage circuit into an analog signal, and an output of the digital-analog converter and an output of the position error signal generation circuit. A magnetic head positioning circuit comprising: an addition amplifier that adds the sum and inputs the result to the power amplifier.