JP2003208701A - Data storage device, amplifier for magnetoresistive effect head of data storage device, and method for reproducing data from data storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable data storage device by changing over an input part of a reproduction amplifier for a magnetoresistive effect head of a hard disk drive in accordance with the head characteristic, a recording signal frequency, a recording medium, etc. <P>SOLUTION: The amplifier for the magnetoresistive effect head of the data storage device is provided with a 1st bias circuit 1 for supplying a bias current to a 1st terminal of a magnetoresistive effect head element, a 1st switch 2 connected to a 2nd terminal of the above head element so as to enable the selection of other connecting ends, a 2nd bias circuit 3 for supplying the bias current to the 2nd terminal of the head element through the above 1st switch, a 2nd switch 4 connectable to the 2nd terminal of the head element or a reference voltage source, and an initial stage amplifier circuit 5 for amplifying the voltage difference between the 1st terminal of the head element and the 2nd switch to output a read signal. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed magnetic recording / reproducing apparatus equipped with a magnetoresistive head.
In particular, the present invention relates to a reproducing amplifier for a magnetoresistive head and a reproducing method using this reproducing amplifier.

[0002]

2. Description of the Related Art In a fixed magnetic recording / reproducing apparatus (HDD: hard disk drive), various elemental technologies have been developed in response to an ever-increasing demand for improvement in recording density. Elements that determine the recording density of the HDD include a magnetic head, a magnetic recording medium, a recording / reproducing circuit, and a magnetic head positioning mechanism. In order to further improve the recording density in the future, it is important not only to improve each elemental technology, but also to comprehensively examine a system that combines each elemental technology. For example, in order to achieve an ultra-high density HDD, it is necessary to dramatically improve the linear recording density (BPI) on each track of the magnetic disk and the recording density (track density) in the radial direction (TPI). come.

As for the magnetic head, there is a GMR (Giant Magneto-Resistance) head, and an HDD adopting this has a high reproducing sensitivity of a magnetic recording signal and largely contributes to the improvement of a linear recording density mainly on a track of a magnetic disk. ing. G
Regarding magnetic recording media for recording data read by an MR head, technologies such as low noise and high coercive force have been improved. In a magnetic head controller (HDI: head disk interface) and a mechanical servo system, a technique for reducing the flying height of the head and a head positioning technique have been improved, and have greatly contributed to the improvement of the recording density in the radial direction of the disk.

The hard disk drive is a CLV such as CD-ROM, DVD-ROM, FD which is another recording medium.
(Constant Linear Velocity
Unlike y), the CAV (Co
This is the Instant Angular Velocity) method. Therefore, the angular velocity of rotation does not change depending on the radial position, but the linear velocity differs depending on the position. That is, the linear velocity is higher on the outer circumference than on the inner circumference of the magnetic disk. Therefore, if the recording frequency of the data to be recorded on the magnetic disk is constant, the minimum magnetization reversal interval between adjacent data on the data track becomes wider on the outer circumference side of the disk than on the inner circumference side. Goes down. That is, it can be said that the outer peripheral side is more wasteful in terms of recording density than the inner peripheral side. In order to eliminate this drawback, the recording area of the magnetic disk is divided into several zones (for example, 16 zones or 8 zones) in the radial direction, and the recording frequency is changed for each zone to change the number of sectors. There is a way. This reduces the gap between the minimum magnetization reversal intervals depending on the radius. This method is called Zone Bit Recording (ZB
R) method or constant density recording (Constant Dens)
It is called an "ity Recording" method. By this method, the linear recording density is changed and optimized according to some zones, so that the BPI (B
It per inch) can be increased.

As for the reproducing amplifier for amplifying the reproducing output of the magnetic head for reproducing the data recorded as described above, the power consumption, the amplification factor, the input conversion noise, etc. have been improved. A differential-end type circuit is used for the input part of the high-performance model regenerative amplifier, and a single-end type circuit is used for the input part of the low-cost model regenerative amplifier, depending on the model and application. I use them properly.

The differential end type circuit is a differential amplifier in which both terminals of the magnetic head are connected to a bias circuit for supplying positive and negative bias currents, respectively, and a voltage generated between both terminals of the magnetic head by detecting a magnetic field. Is an input circuit for inputting into a 2-input amplifier, and the circuit configuration is rather complicated. Also, with a single-ended type circuit, one terminal of the magnetic head is connected to the circuit ground,
This is a circuit in which the other terminal is connected to a positive or negative bias circuit and the voltage generated at the other terminal due to the detection of the magnetic field is input to a two-input amplifier, and the circuit configuration is relatively simple.
The magnetic head, the magnetic disk and the amplifier of the hard disk drive are housed in a highly conductive metal case, which is electrostatically shielded from the outside and completely sealed.

[0007]

In the above-described conventional magnetoresistive head amplifier, the differential end type circuit has a high response frequency and is less affected by fluctuations in the power supply voltage. However, the cost is high, the power consumption is high, and a high power supply voltage is required. On the other hand, the single-end type circuit is inexpensive and consumes less power because of its simple circuit configuration. However, it has a low response frequency and is easily affected by fluctuations in the power supply voltage. There is also a demerit that the magnetic head is weak against electrostatic breakdown. This is because one terminal of the magnetic head is grounded, and there is a greater risk that the other terminal will come into contact with the human body or the like and high-voltage static electricity will be applied. Current hard disk drives are equipped with either a differential end type or a single end type circuit, depending on the model.
Therefore, the same hard disk drive can operate with only one type.

A conventional example of a method of switching between the single end type circuit and the differential end type circuit is disclosed in Japanese Patent Laid-Open No. 03-255515. However, in this conventional example, in the head amplifier of the hard disk drive, switching of signals at the interface between the magnetic head and the amplifier is not specifically shown. The present invention provides a highly reliable data storage device by switching the input section of a reproducing amplifier for a magnetoresistive head of a hard disk drive according to the characteristics of the head, the frequency of a recording signal, the recording medium, and the like. The purpose is to

[0009]

According to a first aspect of the present invention, there is provided a data storage device comprising: a first bias circuit connected to a first terminal of a magnetoresistive head element for supplying a bias current; A two-input amplifier circuit having a first input terminal connected to a first terminal of the head element;
Is connected to the second terminal, and a bias current is applied to the second terminal of the head element via the first switch that selects the connection destination of the second terminal from the circuit ground and the second bias circuit. A second bias circuit to be supplied and a second input terminal of the two-input amplifier circuit are selectively connected to either the second terminal of the head element or a reference voltage source,
It has a second switch which is interlocked to select the second terminal of the head element when the first switch is selecting the second bias circuit. With this configuration, the input ends of the same amplifier can be arbitrarily set to the differential end type or the single end type.

According to a second aspect of the present invention, in the magnetoresistive head amplifier, the first switch is a two-way switch, and the second terminal of the head element is connected to the second terminal when switching in the first direction. It is connected to a second bias circuit, and is controlled to connect the second terminal to the circuit ground when switching in the second direction. This makes it possible to select whether one end of the magnetoresistive head is grounded or connected to the second bias circuit.

According to a third aspect of the present invention, in the magnetoresistive head amplifier, the second switch is a two-way switching type switch, and when switching to the first direction, the second terminal of the head element is connected to the second terminal of the head element. The input terminal of the amplifier circuit is connected, and at the time of switching in the second direction, the input terminal of the amplifier circuit is controlled to be connected to the reference voltage source. As a result, it is possible to select whether the channel on one side of the first-stage amplifier circuit is connected to the differential type or fixed.

According to a fourth aspect of the present invention, there is provided a data storage device, wherein a magnetic recording medium for recording and storing data, and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A magnetoresistive head that outputs a corresponding read signal, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and a magnetoresistive head on a magnetic recording medium. Position information detecting section for recognizing the position of the magnetic disk, a buffer storing the data array information recorded on the magnetic recording medium, and position information in the direction along the track of the magnetic disk obtained from the position information detecting section. Is compared with the array information obtained from the buffer, and the input part of the magnetoresistive head amplifier is connected to the differential end type or An end section of the magnetoresistive head amplifier is determined by a terminal section judging section that judges which of the end types is to be set and outputs a control signal indicating the judgment result, and a control signal output from the terminal section judging section. Is provided with an amplifier termination switching unit for switching between a differential end type and a single end type. The optimum amplifier circuit can be configured by switching the input section of the amplifier according to the position of the track on the magnetic recording medium.

According to a fifth aspect of the present invention, there is provided a data reproducing method, wherein a magnetic recording medium for recording and storing data, and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A magnetoresistive head that outputs a corresponding read signal, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and a magnetoresistive head on a magnetic recording medium. Position information detecting section for recognizing the position of the magnetic disk, a buffer storing the data array information recorded on the magnetic recording medium, and position information in the direction along the track of the magnetic disk obtained from the position information detecting section. Is compared with the array information obtained from the buffer, and the input part of the magnetoresistive head amplifier is connected to the differential end type or An end section of the magnetoresistive head amplifier is determined by a terminal section judging section that judges which of the end types is to be set and outputs a control signal indicating the judgment result, and a control signal output from the terminal section judging section. In a data storage device having an amplifier termination switching unit for switching between a differential end type and a single end type, when reproducing the data of the track of the inner peripheral portion of the magnetic recording medium, the magnetoresistive head amplifier Is set to a single end type, and the data of the magnetic resistance effect type head amplifier is set to a differential end type to reproduce the data recorded on the magnetic recording medium when reproducing the data of the track on the outer peripheral portion. Reproduce. According to this method, it is possible to set the single end type on the inner peripheral side where the recording frequency is low, and to set the end suitable for each differential type track on the outer peripheral side where the recording frequency is high.

A data recording medium recorded with the method for reproducing data recorded on the recording medium according to claim 6, recording and storing the data on a magnetic recording medium,
Outputting a read signal according to a resistance value between both terminals of the magnetoresistive head that changes by detecting information recorded on the magnetic recording medium; and outputting the read signal from the magnetoresistive head. Amplifying and outputting the read signal, recognizing the position on the track of the magnetic recording medium of the magnetoresistive head from the read signal, and data array information previously recorded on the magnetic recording medium in a buffer The step of storing, comparing the information on the position on the track of the magnetic disk with the array information obtained from the buffer, the input part of the magnetoresistive head amplifier is set to either a differential end type or a single end type. Step of determining whether to set, based on the determination result, the magnetoresistive effect type Of instructing the input section of the differential amplifier to select either the differential end type or the single end type, and switching the input section of the magnetoresistive head amplifier to either the differential end type or the single end type In a data reproducing method of a data storage device having a step, in a track of a predetermined inner peripheral portion of a magnetic recording medium, an input portion of the magnetoresistive head amplifier is set to a single end type, and a track of a predetermined outer peripheral side portion is set. Describes a method of reproducing data recorded on a magnetic recording medium by setting the input part of the magnetoresistive head amplifier to a differential end type. It is possible to provide a magnetic disk which can be set to a single end type on the inner peripheral side where the recording frequency is low, and a differential end type which can be set to an appropriate end on the outer peripheral side where the recording frequency is high.

According to a seventh aspect of the present invention, there is provided a data storage device in which a magnetic recording medium for recording and storing data and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A magnetoresistive head that outputs a corresponding read signal, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and a magnetoresistive head based on the read signal Area detecting section for recognizing the position in the direction along the track on the magnetic recording medium surface, a buffer storing data array information recorded in advance on the magnetic recording medium, and a position obtained from the area detecting section The information is compared with the array information obtained from the buffer, and the input section of the magnetoresistive head type amplifier is connected to the differential end type or The end of the magnetoresistive head type amplifier is judged to be the differential end type or the single end by the control signal. It is characterized by having an amplifier termination switching unit for switching to any of the end types. With this configuration, it is possible to switch to the optimum amplifier input section according to the frequency of the signal recorded on the track being accessed.

According to a eighth aspect of the present invention, there is provided a data reproducing method in which a magnetic recording medium for recording and storing data, and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A magnetoresistive effect head that outputs a corresponding read signal, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and a magnetic recording medium of a magnetoresistive head. From the area detection unit for recognizing the position in the direction along the upper track, the buffer in which the data array information previously recorded in the magnetic recording medium is stored, the position information obtained from the area detection unit and the buffer By comparing the obtained array information, the input part of the magnetoresistive head amplifier is connected to the differential end type or the single end type. Of the differential end type or the single end type input terminal of the magnetoresistive head amplifier is determined by the control signal and the terminal determination section that outputs a control signal indicating the determination result. In a data storage device having an amplifier termination switching unit for switching to any one, in a servo area of a track of a magnetic recording medium, an input unit of the magnetoresistive head type amplifier is set to a single end type, and in a data area, The input section of the magnetoresistive head amplifier is set to the differential end type to reproduce the data recorded on the magnetic recording medium. According to this method, the end of the amplifier should be a single-ended type in the servo area where the recording frequency is low even in the same track, and the differential type should be set in the data area where the recording frequency is high, and the input section suitable for each area should be set. Is possible.

A data recording medium recording the method for reproducing the data recorded on the recording medium according to claim 9, the step of recording and storing the data on a magnetic recording medium,
Outputting a read signal according to a resistance value between both terminals of the magnetoresistive head that changes by detecting information recorded on the magnetic recording medium; and outputting the read signal from the magnetoresistive head. Amplifying the read signal with a magnetoresistive head amplifier and outputting it; recognizing the position of the magnetoresistive head in the direction along the track on the magnetic recording medium surface; prerecording on the magnetic recording medium. A step of storing certain data array information in a buffer, comparing the position information obtained from the area detection part with the array information obtained from the buffer, and setting the input part of the magnetoresistive head amplifier to a differential end type or The step of deciding which of the single end type to set, the magnetic resistance effect depending on the judgment result For instructing whether the input end of the head amplifier for differential type is a differential end type or a single end type, and switching the input part of the magnetoresistive head amplifier for a differential end type or a single end type In a data reproducing method of a data storage device having a step, in a servo area of the magnetic recording medium, an input portion of the magnetoresistive head amplifier is set to a single end type, and in a data area, the magnetoresistive head head is used. The method of reproducing the data recorded in the magnetic recording medium by setting the input part of the amplifier to the differential end type is recorded. In the servo area where the recording frequency is low, the single end type is used. In the data area where the recording frequency is high, the amplifier input section is made the differential end type, and the playback method that can be set to the input section suitable for each area is recorded. A recording medium can be provided.

According to a tenth aspect of the present invention, a data storage device has a magnetic recording medium for recording and storing data, and a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. A magnetoresistive effect head that outputs a corresponding read signal, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and measures the resistance value of the magnetoresistive head. Head resistance value measuring unit, a head resistance value table that is a memory storing the resistance value threshold of the magnetoresistive head, head resistance value information obtained from the head resistance value measuring unit, and the head resistance value. Comparing with the information obtained from the table, the input part of the magnetoresistive head amplifier is set to the differential end type or the single end type. Which of the differential end type and the single end type the input section of the magnetoresistive head amplifier is determined by the terminal determination section which determines which is set and outputs a control signal indicating the determination result, and the control signal. It is characterized in that it has an amplifier termination switching unit for switching to or from. With this configuration, the input section of the magnetoresistive head amplifier can be switched to an optimum one according to the characteristics of the magnetoresistive head used in combination with the input section.

According to another aspect of the data storage device of the present invention, a plurality of magnetoresistive effects are provided, which output a read signal according to a resistance value between both terminals which changes by detecting information recorded on a magnetic recording medium. Type head and a head resistance value measuring section for measuring the resistance value of each of the plurality of magnetoresistive heads, and the differential end type differential head type input section of the magnetoresistive head amplifier according to the resistance value. Alternatively, it is characterized in that it is set to either a single end type. Even in a device having a plurality of heads, the same effect as described above can be obtained for each head.

According to a twelfth aspect of the present invention, there is provided a data reproducing method, wherein a magnetic recording medium for recording and storing data, and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A plurality of magnetoresistive effect type heads for outputting corresponding read signals, a magnetoresistive effect type head amplifier for amplifying and outputting the read signals outputted from the magnetoresistive effect type head, and a resistance value of the magnetoresistive effect type head From the head resistance value measuring unit for measuring the, the head resistance value table storing the threshold value of the resistance value of the magnetoresistive head, the head resistance value information obtained from the head resistance value measuring unit and the head resistance value table. Comparing with the obtained information, the input part of the magnetoresistive head amplifier is either a differential end type or a single end type. It is determined whether to set, the terminal determination unit that outputs a control signal indicating the determination result, and the input signal of the magnetoresistive head amplifier to the differential end type or the single end type according to the control signal. In a data storage device having an amplifier termination switching unit for switching, the resistance value of the magnetoresistive head measured by the head resistance value measuring unit is compared with a threshold value stored in the head resistance value table. When amplifying the read signal of the magnetoresistive head whose resistance value exceeds the threshold value, the input section is set to the differential end type and the magnetoresistive effect head whose resistance value is equal to or less than the threshold value is read. When amplifying a signal, the input section is set to a single end type. According to this method, in the same device, in the magnetoresistive head having a lower resistance value, the input portion of the amplifier is a single-ended type, and the resistance value is high, so that the magnetoresistive element is likely to be relatively electrostatically damaged. For the effect type head, use the differential end type,
It is possible to set an input unit suitable for each head characteristic.

According to a thirteenth aspect of the present invention, there is provided a data reproducing method in which a magnetic recording medium for recording and storing data and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A plurality of magnetoresistive heads for outputting corresponding read signals, a magnetoresistive head amplifier for amplifying and outputting the read signals output from the magnetoresistive head, and a resistance value of the magnetoresistive head From the head resistance value table obtained by measuring the head resistance value measuring unit, the head resistance value table storing the threshold value of the resistance value of the magnetoresistive head, and the head resistance value information obtained from the head resistance value measuring unit. Compared with the obtained information, the input part of the magnetoresistive head amplifier is either of a differential end type or a single end type. A terminal determination unit that determines whether to set and outputs a control signal indicating the determination result, and switches the input unit of the magnetoresistive head amplifier to either a differential end type or a single end type according to the control signal. In a data storage device having an amplifier termination switching unit for amplifying a read signal of a magnetoresistive head whose resistance value measured by the head resistance value measuring unit exceeds 55 ohms,
The differential end type input section is selected, and when amplifying the read signal of the magnetoresistive head having a resistance value of 55 ohms or less, the single end type input section is selected. According to this method, in the same device, in the magnetoresistive head having a resistance value lower than 55 ohms, the termination of the amplifier is made a single end type, and the resistance value is higher than 55 ohms and it is relatively easy to be electrostatically destroyed. It seems that the magnetoresistive head can be set to the differential end type.

According to a fourteenth aspect of the present invention, there is provided a magnetic disk comprising: a step of recording and storing data on a magnetic recording medium; and both terminals of a magnetoresistive head which is changed by detecting information recorded on the magnetic recording medium. A read signal corresponding to a resistance value between the two, a step of amplifying the read signal output from the magnetoresistive head by a magnetoresistive head amplifier and outputting the read signal, and a resistance of the magnetoresistive head. A step of measuring a value, a step of storing the threshold value of the resistance value of the magnetoresistive head in a resistance value table, head resistance value information obtained from the head resistance value measuring unit and information obtained from the head resistance value table. And the input section of the magnetoresistive head amplifier is a differential end type or a single end type. The step of determining which to set, the step of instructing whether the input part of the magnetoresistive head amplifier for differential end type or single end type according to the determination result, and the magnetic field according to the instruction In a method of controlling a data storage device having a step of switching an input section of a resistance effect head amplifier to either a differential end type or a single end type, in the magnetoresistive effect head measured by the head resistance value measuring section, When the resistance value is compared with the threshold value obtained from the head resistance value table memory and the read signal of the magnetoresistive head in which the resistance value exceeds the threshold value is amplified, the input section is set to the differential end type, A magnetoresistive effect head whose resistance value is below the threshold value. When amplifying the read signal is recorded a control method for a single-ended type input unit. In the same device, the magnetoresistive head with a lower resistance value has a single-ended type for the input part of the amplifier, and the magnetoresistive head with a higher resistance value is likely to be relatively easily destroyed by electrostatic damage. Thus, it is possible to provide a reproducing method capable of setting an input unit suitable for each head characteristic.

According to a fifteenth aspect of the present invention, in a data storage device, a magnetic recording medium for recording and storing data, and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium are used. A magnetoresistive head for outputting a corresponding read signal, a magnetoresistive head amplifier for amplifying the read signal output from the magnetoresistive head and outputting a differential analog signal, the magnetoresistive head A read channel unit that converts the differential analog signal output from the head amplifier into digital data, an error rate measuring unit that calculates an error rate from the digital data obtained from the read channel unit, and an error rate measuring unit. A configuration table having a memory for storing an error rate result, said configuration table In accordance with the voltage value determined by the voltage determining unit, and the voltage determining unit for instructing the value of the optimum voltage to be supplied to the first stage amplifier of the magnetoresistive head amplifier by referring to the data of the simulation table. It is characterized in that it has a voltage value changing unit for changing the value of the voltage supplied to the first stage amplifier of the magnetoresistive head amplifier. According to this configuration, it is possible to give an optimum supply power supply voltage to the amplifier circuit, which has different reproduction characteristics depending on the supplied power supply voltage, to operate it.

According to a sixteenth aspect of the present invention, there is provided the magnetoresistive head amplifier, wherein the voltage value changing unit is included in the magnetoresistive head amplifier. The above device can be realized without adding extra components to the outside of the amplifier.

According to a seventeenth aspect of the present invention, there is provided a magnetoresistive effect head amplifier capable of changing the value of the voltage supplied to each of the magnetoresistive effect head amplifiers corresponding to a plurality of magnetoresistive effect heads. A possible voltage value changing unit is provided in the magnetoresistive head amplifier. Even in a multi-channel amplifier corresponding to a plurality of heads, the above-mentioned device can be realized without adding extra parts to the outside of the amplifier for each channel.

According to a eighteenth aspect of the present invention, there is provided a data reproducing method, wherein a magnetic recording medium for recording and storing data, and a resistance value between both terminals which is changed by detecting information recorded on the magnetic recording medium. A magnetoresistive head that outputs a corresponding read signal, a magnetoresistive head amplifier that amplifies the read signal output from the magnetoresistive head and outputs a differential analog signal, and the magnetoresistive head A read channel unit that converts the differential analog signal output from the head amplifier into digital data, an error rate measurement unit that calculates an error rate from the data obtained from the read channel unit, and an error measured by the error rate measurement unit A configuration table having a memory for storing rate results, said configuration table By referring to the data of emissions table,
A voltage determining unit that indicates an optimum voltage value to be supplied to the first-stage amplifier of the magnetoresistive head amplifier, and a voltage supplied to the magnetoresistive head amplifier according to the voltage value determined by the voltage determining unit. In a data storage device having a voltage value changing unit for changing the value, the voltage value changing unit changes the value of the voltage supplied to the magnetoresistive head amplifier stepwise, and the voltage values changed stepwise. And the voltage at the lowest error rate is supplied to the magnetoresistive head amplifier. According to this method, even for amplifier circuits that have different reproduction characteristics depending on the supplied power supply voltage, the optimal measured supply power supply voltage is checked in advance, and instructions are given to each device so that the optimum supply power supply voltage is obtained. Can be set to operate.

According to a nineteenth aspect of the present invention, in the magnetic disk according to the nineteenth aspect, the steps of recording and storing data on a magnetic recording medium and both terminals of a magnetoresistive head that changes by detecting information recorded on the magnetic recording medium. For outputting a read signal according to a resistance value between the magnetoresistive head, amplifying the read signal output from the magnetoresistive head with an amplifier for the magnetoresistive head, and outputting the amplified signal, for the magnetoresistive head Changing the voltage value supplied to the amplifier; converting the differential analog signal output from the magnetoresistive head amplifier to digital data; calculating an error rate based on the digital data; Storing the error rate calculation result in a configuration table, which is a memory, In the method of controlling a data storage device, which comprises a step of deciding and instructing an optimum voltage value by a voltage deciding unit by referring to the data of the configuration table, the value of the voltage supplied to the magnetoresistive head amplifier is stepwise changed. Error rate for each voltage value changed stepwise, and the voltage at the lowest error rate is supplied to the magnetoresistive head amplifier. The voltage value changing unit is used to stepwise change the voltage value supplied to the magnetoresistive head amplifier, and the optimum value of the voltage value during amplification is obtained from the error rate for the voltage value. Then, the magnetic disk is compared with a preset voltage value at the time of desired amplification, the voltage value is updated according to the difference, and the next time voltage supply can be performed with the desired voltage value. Can be provided.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to FIGS. << First Embodiment >> FIG. 1 shows a circuit diagram of a regenerative amplifier 9 for a magnetoresistive head (hereinafter abbreviated as regenerative amplifier) according to a first embodiment of the present invention. In a magnetoresistive head, which is a reproducing magnetic head, the resistance value between both terminals of a conductor of the magnetic head changes due to the magnetoresistive effect due to the magnetization representing the information recorded on the magnetic recording medium. Since a bias current is passed through the conductor, the voltage between both terminals changes according to the change in the resistance value. Magnetization is detected by detecting this voltage change. Regenerative amplifier 9 shown in FIG.
Is a first bias circuit 1 for supplying a bias current to a first terminal 100A of a magnetoresistive head element 100 represented by an equivalent resistance R100, and the head element 100.
Has a first switch 2 which is connected to the second terminal 100B of the above and whose connection destination can be selected from the circuit ground G and the second bias circuit. The regenerative amplifier 9 is further connected to the second terminal 1 of the head element 100 via the first switch 2.
A second bias circuit 3 for supplying a bias current to 00B, a second switch 4 for switching between the second terminal 100B of the head element 100 and the reference voltage source 6, and a first terminal 100A of the head element 100. The first stage amplifier circuit 5 is provided for amplifying the voltage difference between the second switches 4 and amplifying the read signal obtained by reproducing the recorded information on the magnetic recording medium.

In the regenerative amplifier 9 of this embodiment, by switching the interlocked switches 2 and 4, the type of the input portion of the regenerative amplifier 9, that is, the type of connection between the head element 100 and the first-stage amplifier circuit 5, is described below. You can switch to either. "Input section" means switches 2 and 4,
A circuit portion including the head element 100, the capacitors C3 and C4, and the reference voltage source 6. Switches 2 and 4 shown in FIG.
The two terminals 100A and 100B of the head element 100, which are connected to each other, are connected to the two input terminals 5A of the first-stage amplifier circuit 5, which is a differential amplifier, via respective capacitors C3 and C4.
The connection format for connecting to 5B is called "differential end type". The terminal 100B is connected to the second bias circuit 3. Further, when the switches 2 and 4 are switched to connect the terminal 100B to the circuit ground G and connect the input end 5B to the positive electrode of the reference voltage source 6, that is, one terminal 100A of the head element 100 is connected via the capacitor C3. Is connected to one input terminal 5A of the first-stage amplifier circuit 5, and the other terminal 100B is connected to the other input terminal 5B of the first-stage amplifier circuit 5 via the reference voltage source 6 is called a "single-end type".

A single end type circuit (hereinafter abbreviated as single end) and a differential end type circuit (hereinafter
It is as follows when comparing the advantages and disadvantages of (differential end). At the differential end, it operates with two positive and negative power supplies. On the other hand, in the single end, it operates with one positive or negative power source. The upper limits of the positive and negative power supply voltages are usually the same because they are determined by the operating voltages of circuit elements such as semiconductor elements used. Therefore, a differential end that operates with two positive and negative power supplies will have twice the dynamic range of a single end that operates with one positive or negative power supply. In a general amplifier circuit, the larger the dynamic range, the wider the frequency range, and it becomes possible to amplify a higher frequency signal. That is, the differential end has excellent high frequency characteristics. Further, since differential amplification is performed at the differential end, the in-phase component of noise generated in the amplifier circuit is canceled and the S / N ratio is higher than that at the single end. The above is the advantage that the differential end is superior to the single end. The disadvantage of the differential end over the single end is that the differential end uses two positive and negative power supplies, the circuit configuration is complicated, and the power consumption is higher than that of the single end.

In this embodiment, when the frequency of the reproduction signal from the magnetic disk is high, for example, the reproduction signal from the track on the outer peripheral portion of the magnetic disk having a high linear velocity has a high frequency, so that the high frequency characteristics and the S / N ratio are high. Amplify using a differential end with an excellent ratio. On the other hand, the frequency of the reproduction signal of the track on the inner peripheral side where the linear velocity is low is low,
It is inferior in terms of high-frequency characteristics, but it amplifies using a single end with low power consumption.

First, the reproducing amplifier 9 for the differential end magnetoresistive head will be described. At the differential end, as shown in FIG. 1, the switch 2 includes a terminal 100B and a second bias circuit 3
Output terminal 3A is connected, and switch 4 connects capacitor C4 and input terminal 5B of first-stage amplifier circuit 5. In FIG. 1, the first bias circuit 1 includes an NPN transistor Q1 connected via a resistance element R1 between a supply line 60 of a positive power supply voltage VCC and an output terminal 1A, and between the supply line 60 and the base of the transistor Q1. Connected capacitor C
Has 1. The emitter of the transistor Q1 is connected to the supply line 60 of the power supply voltage VCC via the resistance element R1, and the collector is connected to the output end 1A. In the first bias circuit 1, the electric current flowing from the control input terminal 1B to the base of the transistor Q1 is controlled by a control circuit (not shown), so that the potential of the terminal 100A of the head element 100 can be determined.

The second bias circuit 3 includes a capacitor C2,
It has a resistance element R2 and a PNP transistor Q2, and the emitter of the transistor Q2 is connected to the supply line 70 of the negative power supply voltage VEE via the resistance element R2. Since the first switch 2 selects the second bias circuit 3, the collector of the transistor Q2 is the head element 100.
Is connected to the terminal 100B. The capacitor C2 is connected between the base of the transistor Q2 and the supply line 70 of the power supply voltage VEE. In the second bias circuit 3, the current flowing from the control input terminal 3B into the base of the transistor Q2 is controlled by a control circuit (not shown), so that the terminal 100B of the head element 100 can be controlled.
The potential of can be determined. In the head element 100,
A current flows according to the respective potentials of both terminals 100A and 100B of the head element 100.

Since the second switch 4 selects the capacitor C4, both terminals 100 of the head element 100 are
The AC component of the voltage difference between A and 100B is the capacitor C
It is input to the input terminals 5A and 5B of the first-stage amplifier circuit 5 via 3 and C4. When the head element 100 passes through the magnetized portion showing the recorded data of the magnetic disk, the resistance value of the equivalent resistance R100 of the head element 100 changes. The voltage between the terminals 100A and 100B changes due to the change in the resistance value. The signal of this changing voltage is amplified several tens of times by the first stage amplifier circuit 5 and sent to the next stage amplifier circuit 8.

Next, the reproducing amplifier 9 for a single-ended magnetoresistive head will be described. In the single end, the switch 2 connects the terminal 100B to the ground G which is the circuit ground, and the switch 4 connects the input terminal 5B of the first stage amplifier circuit 5 to the reference voltage source 6. First
In the bias circuit 1 of 1, the head element 10 is controlled by controlling the current flowing into the base of the transistor Q1.
The potential of the terminal 100A on one side of 0 is determined. By the first switch 2, the potential of the terminal 100B of the head element 100 becomes the same as the ground G. Terminal 1 of the head element 100
The AC component of the voltage of 00A is input to the terminal 5A of the first-stage amplifier circuit 5 via the capacitor C3. Second switch 4
Since the reference voltage of the reference voltage source 6 is applied to the other terminal 5B of the first-stage amplifier circuit 5, the potential of the terminal 5B is constant. According to the present embodiment, the input section of the first-stage amplifier circuit 5 including the head element 100 can be switched to either the differential end type or the single end type by a simple operation of switching the switches 2 and 4.

<Second Embodiment> FIG. 2 shows a block diagram of a data storage device for reproducing data recorded on a magnetic recording medium according to a second embodiment of the present invention. In the figure,
The data storage device of this embodiment includes a magnetic recording medium 16 for recording and storing data, a plurality of magnetoresistive heads 17 for detecting magnetizations indicating information recorded on both surfaces of the magnetic recording medium, Magnetoresistive head 17
It has a magnetoresistive head amplifier 18 that amplifies and outputs the read signal output from the head. The magnetoresistive head amplifier 18 is the regenerative amplifier 9 of the first embodiment.
Is equipped with. The data storage device further stores a position information detection unit 19 for recognizing the position of the magnetoresistive head 17 on the magnetic recording medium 16 and data array information of data previously recorded in the magnetic recording medium 16. With buffer 10 present. Further, the position information in the direction along the track of the magnetic disk 16 obtained from the position information detection unit 19 is compared with the data array information referred to in the buffer 10 to determine how the input unit of the magnetoresistive head amplifier 18 is connected. It has a terminal end determination unit 11 that determines whether or not to set. The input portion of the magnetoresistive head amplifier 18 is
It is switched by the amplifier termination switching unit 13 according to the control signal 12 instructing the differential end type or the single end type.

On the magnetic recording medium 16, ordinary data used by the user and servo data which is position information are recorded in advance by an inductive head (inductive head) for recording (not shown). The position information can be read when the magnetoresistive head 17 passes through the magnetized portion of the servo data. The magnetoresistive head amplifier 18 supplies a bias current 18A to the magnetoresistive head 17 and reproduces the reproduced signal 1 from the head 17.
Amplify 8B. The value of the bias current is, for example, about 3 mA. The amplification factor (gain) of the magnetoresistive head amplifier 18 is usually about 150 to 200 times. For example, when the amplitude of the magnetoresistive head 17 is 500 μV and the gain is 180 times, the output voltage can be calculated by the following formula (1).

[0038]   500 μV × 180 = 90 mV (1)

The magnetoresistive head amplifier 18 has two stages, the first stage and the second stage, similar to that shown in FIG. 1 of the first embodiment.
If there are a plurality of magnetoresistive heads 17, one for each magnetoresistive head 17 is provided for each of the magnetoresistive heads. For example, a 4-channel magnetoresistive effect head amplifier 18 provided with four magnetoresistive effect heads has four first-stage amplifier circuits 5, and the amplification factors thereof are about 60 times, respectively. The number of the amplifier circuit 8 at the next stage is usually one, and the output of the desired first stage amplifier circuit 5 of the magnetoresistive head 17 is selected by the head select signal and input to the amplifier circuit 8. The reproduction servo data output from the magnetoresistive head amplifier 18 is sent to the position information detector 19. The position information detecting unit 19 identifies the track position in the radial direction of the magnetic recording medium 16 that the magnetoresistive head 17 is currently accessing by reading the position signal of the servo data. The buffer 10 stores a track format table, which is array information of data recorded on the magnetic recording medium 16.

An example of the track format table stored in the buffer 10 is shown in Table 1 below.

[0041]

[Table 1]

These data in the buffer 10 are rewritable and can be updated at any time. These data may be written in a memory device such as a non-volatile memory or a specific area other than the data area of the magnetic recording medium.

The terminating section determining section 11 includes a position information detecting section 19
The number of the track currently being accessed is read from the detection data of the magnetoresistive head and the magnetoresistive head including the magnetoresistive head 17 is referred to by referring to the track number and the table information in Table 1 stored in the buffer 10. Amplifier 1
It is determined whether the input part of 8 should be a differential end type or a single end type.
Table 1 divides the track from the outermost circumference to the innermost circumference of the magnetic disk 16 into 15 zones, and shows the leading track number and the trailing track number of each zone. "Type of input section" in the right column indicates that the input section of the magnetoresistive head reproducing amplifier 18 is a differential end for zone numbers 0 to 7 and a single end for zone numbers 8 to 14. ing. For example, if the track number is 5963 from the track number information input from the position information detection unit 19, it is determined from Table 1 that the differential end is selected. Further, if the track number is 11965 from the track number information input from the position information detection unit 19, it is determined from Table 1 that single end is selected. The zone number (track number) for switching from the differential end to the single end is determined by examining the data frequency and power consumption at the product design, mass production trial stage, and evaluation process, and the table information in the buffer 10 is updated. deep. A control signal 12 that determines the type of the input section of the magnetoresistive head amplifier 18 determined by the terminal section determination section 11 is applied to the amplifier terminal switching section 13. The amplifier termination switching unit 13 applies the switching signal 13A to the magnetoresistive head amplifier 18, and switches the input unit to either the differential end type or the single end type. Subsequent reproduction of data is performed by the magnetoresistive head amplifier 18 of the switched type input section. The above operation is performed each time the magnetoresistive head 17 accesses a new track. As a result, the input section can always be of the optimum type and the detection sensitivity of the magnetoresistive head can be kept in the optimum state.

<< Third Embodiment >> A block diagram of a data storage device for reproducing data recorded on a magnetic recording medium according to a third embodiment of the present invention is shown in FIG. The data storage device of this embodiment is a magnetoresistive head 1 that detects information recorded on a magnetic recording medium 16 and outputs a read signal.
7. An area detector 24 for recognizing the position of the magnetoresistive head amplifier 18 for amplifying and outputting the read signal and the position of the magnetoresistive head 17 in the direction along the track on the surface of the magnetic recording medium 16. Have. The data storage device is further a format table 1 which is a memory storing the data array information recorded on the magnetic recording medium.
5. Compare the position information obtained from the area detection unit 24 with the sequence information referred to from the format table 15,
It has a terminating section deciding section 11 for deciding how to set the input section of the magnetoresistive head amplifier. The data storage device further includes an amplifier terminal for switching the input portion of the magnetoresistive head type amplifier 18 according to a control signal line 12 for instructing whether to select the differential end type or the single end type. It has a switching unit 13.

Servo data having position information is recorded in advance on the tracks of the magnetic recording medium 16. The position information is read by detecting the servo data recorded on the magnetic recording medium 16 by the magnetoresistive head 17. On a normal track, a servo area having servo data and a data area for recording data are mixed. Magnetoresistive head amplifier 18
Amplifies the reproduction signal from the magnetoresistive head 17. The track position information output from the magnetoresistive head amplifier 18 is sent to the area detector 24. The format table 15 stores temporal information indicating the servo area and the data area of the track in each zone recorded on the magnetic recording medium 16. Based on the current position information of the magnetoresistive head 17 obtained from the magnetoresistive head amplifier 18 and the format information obtained from the format table 15, the area detector 24 indicates that the magnetoresistive head 17 is currently on the track. Whether it is in the servo area or the data area is detected.

The terminating section judging section 11 receives the information of the area on the currently accessed track from the area detecting section 24 and judges which type the input section should be. When the information from the area detection unit 24 indicates a data area including high frequency data, the terminal end determination unit 11 determines to select the differential end. When the area information from the area detection unit 24 indicates a servo area including data of a relatively low frequency, it is determined to select single end. The type of the input section determined by the termination section determination section 11 is instructed to the amplifier termination switching section 13 by the control signal 12. The amplifier termination switching unit 13 switches the input unit of the magnetoresistive head amplifier 18 based on the determination, and reproduces data. This operation is performed each time the magnetoresistive head 17 performs a seek operation to access another track so that the optimum input section is always selected depending on whether the area being reproduced is the data area or the servo area. To do.

In the data storage device of the present embodiment, the input section is switched to the single end type in the servo area where the frequency of the reproduced signal is low in the area of the track to be accessed, and is switched to the differential end type in the data area where the frequency is high. As a result, the data can be reproduced by the input unit of the type suitable for the reproduced signal. In the second embodiment, the type of the input unit is switched according to the range of track numbers, and in the third embodiment, the type of the input unit is switched according to the type of recording data such as the servo area and the data area. By combining the second embodiment and the third embodiment, the input unit is switched according to both the range of track numbers and the type of recording data, and a data storage device capable of always selecting the optimum input unit is obtained.

<Fourth Embodiment> FIG. 4 shows a block diagram of a data storage device for reproducing data recorded on a magnetic recording medium according to a fourth embodiment of the present invention. The data storage device of this embodiment detects the information recorded on the magnetic recording medium 16 and outputs a read signal to the magnetoresistive head 1.
7. A head resistance value measuring unit 25 for measuring the resistance value of the magnetoresistive head amplifier 18 for amplifying and outputting the read signal and the magnetoresistive head 17. The data storage device further includes a head resistance value table 26, which is a memory that stores a resistance threshold value of the magnetoresistive head 17, and head resistance value information obtained from the head resistance value measuring unit 25 and the head resistance value. The terminal determination unit 11 that compares the threshold information referred to from the table 26 to determine which type the input of the magnetoresistive head amplifier 18 is set to and outputs the control signal 12 is provided. The data storage device further includes an amplifier termination switching unit 13 for switching the input unit of the magnetoresistive head amplifier 18 to either a differential end type or a single end type according to the control signal 12.

Next, the operation will be described. A constant bias current 18A is supplied to the magnetoresistive head 17 from the magnetoresistive head amplifier 18. The voltage generated between both terminals of the magnetoresistive head 17 is amplified and applied to the head resistance value measuring unit 25. Head resistance value measuring unit 25
Then, according to the amplified voltage, the magnetoresistive head 17
The resistance value of is detected. That is, the magnetoresistive head 1
The resistance value Rmr is obtained from the voltage value Vmr between both terminals of No. 7 and the bias current value Ib using Ohm's law equation (2).

[0050] Rmr = Vmr / Ib ... (2)

As shown in equation (2), the bias current Ib of the magnetoresistive head 17 is expressed as a function of the resistance value Rmr of the head.

The head resistance table 26 stores the threshold value of the resistance of the magnetoresistive head 17. This threshold value is predetermined based on experiments and statistical data at the trial stage of the data storage device. For example, in an experiment at a prototype stage, when it is found that the magnetoresistive head 17 having a resistance value of more than 55 ohms has a greater risk of destruction by static electricity than heads of 55 ohms or less, the threshold value is 55 ohms. Head resistance table 1
Set to 7. The terminal end determination unit 11 receives the information on the resistance value of the magnetoresistive head 17 from the head resistance value measurement unit 25 and determines which type the input unit should be. The resistance value information from the head resistance value measuring unit 25 is compared with the threshold value 55 ohms stored in the head resistance value table 26, and if the resistance value exceeds 55 ohms, it is determined as a differential end type, and the resistance value is determined. Is 55
If it is less than ohms, it is judged as single-ended type.

For example, a determination example in a data storage device having four magnetoresistive heads 17 having head numbers 0 to 3 will be shown below. If the resistance values of the magnetoresistive heads with head numbers 0 and 3 are 49 ohms and 52 ohms, respectively, the threshold value is 55 ohms or less, so the input section is switched to the single-end type. The resistance values of the magnetoresistive heads of head numbers 1 and 2 are 5 respectively.
If it is 7, 58 ohms, it exceeds the threshold value of 55 ohms, so the input section is switched to the differential end type.

The terminating section judging section 11 sends a control signal 12 indicating the type of the input section to the amplifier terminating switching section 13. The amplifier termination switching unit 13 applies a switching signal to the magnetoresistive head amplifier 18 according to the control signal 12, and according to the magnetoresistive head 17 having head numbers 0 to 3, the magnetoresistive head amplifier 18 is applied. Switch the input type of. This operation is performed every time the magnetoresistive head 17 that accesses a desired track changes, so that the optimum input type can be selected for the magnetoresistive head 17 that is being accessed. That is, of the plurality of magnetoresistive heads 17 of the data storage device, the magnetoresistive head 1 in operation is operating.
The type of the input unit is switched according to No. 7, and the input type suitable for each magnetoresistive head is selected. As a result, the magnetoresistive head 17 which has high resistance and is easily damaged by electrostatic discharge can be used as a differential end type input unit to realize a highly reliable data storage device.

Even when the resistance value of the magnetoresistive head 17 changes with temperature, the input section is switched by comparison with the threshold value of the resistance. Therefore, even when the resistance value of the head changes due to a change in the surrounding environment such as a temperature change, the optimum input portion is always switched, so that high reliability can be obtained in reproduction.

<Fifth Embodiment> FIG. 5 shows a block diagram of a data storage device for reproducing data recorded on a magnetic recording medium according to a fifth embodiment of the present invention. The data recording apparatus of this embodiment is for a magnetoresistive head 17 that detects information recorded on the magnetic recording medium 16 and outputs a read signal, and a magnetoresistive head that amplifies and outputs the read signal. It has an amplifier 18. The data storage device further includes a read channel circuit 28 having an A / D converter for converting the differential analog signal output from the magnetoresistive head amplifier 18 into digital data, and the digital data from the read channel circuit 28. An error rate measuring unit 39 that calculates an error rate based on
It has a configuration table 20 having a memory for storing the error rate measured by the error rate measuring section 39. Further, the data storage device refers to the data of the configuration table 20 and determines the voltage value of the power supplied to the first stage amplifier of the magnetoresistive head type amplifier 18 by the voltage determination unit 21 and the voltage determination unit 21. It has a voltage value changing unit 23 that changes the voltage value based on the voltage value. This embodiment relates to control of a data storage device for minimizing data detection error. The error occurrence frequency is measured, for example, before the factory shipment of the data storage device, and the measurement data is stored in the configuration table 20. After factory shipment, based on the measurement data of the configuration table 20, the magnetoresistive head amplifier 1
Control eight. At the time of measurement, the measurement data is recorded in the magnetic recording medium 16, and the same data is also recorded in the internal memory of the error rate measuring unit 39.

First, measurement before factory shipment will be described.
The measurement data recorded on the magnetic recording medium 16 is read by the magnetoresistive head 17, amplified by the magnetoresistive head amplifier 18, and input to the read channel section 28. The read channel unit 28 filters the input analog differential signal, adjusts the level, and digitizes it to obtain detection data. The digitized detection data is input to the error rate measuring unit 39. The error rate measuring unit 39 compares the detection data with the previously recorded measurement data, and checks whether the detection data is the same as the measurement data. As a result of collation, if they do not match, it is judged as an error. For example, the power supply voltage supplied to the magnetoresistive head amplifier 18 is changed from 4.7 V to 5.3 V in 0.1 V increments, and a collation test is performed 1 million times for each voltage. The number of times an error has occurred in one million verification tests is recorded in the configuration table 20 as an error rate. When there are a plurality of magnetoresistive heads 17, the power supply voltage for each magnetoresistive head 17 is 4.7V to 5.
The error rate is measured by changing it by 0.1 V up to 3 V, and the result is recorded in the configuration table 20. Table 2 shows an example of the measurement results.

[0058]

[Table 2]

In Table 2, "head number" represents the two magnetoresistive heads 17, which are indicated by numbers "0" and "1", respectively. Power supply voltage is from 4.7V to 5.
The error rate at each voltage value is measured by changing every 0.1V up to 3V. According to Table 2, in the magnetoresistive head 17 having the head number “0”, the error rate was 18 and the minimum when the power supply voltage was 5.0V. In the magnetoresistive head 17 having the head number “1”, the power supply voltage is 4.
At 9 V, the error rate was 5, which was the minimum. These data are stored in the configuration table 20. The voltage determination unit 21 searches the magnetoresistive head 17 for the optimum voltage value read from the configuration table 20 when the error rate is the smallest. The voltage value instruction signal 22 representing the optimum voltage value obtained by the voltage determination unit 21 is applied to the voltage value changing unit 23, and the power supply voltage to be supplied to the first stage amplifier of the magnetoresistive head amplifier 18 is set based on the voltage value changing signal 23. To do.

An optimum power supply voltage setting method for the magnetoresistive head amplifier 18 in the data storage device of this embodiment will be described in detail with reference to the flowchart of FIG. First, in step 41, initial setting is performed. In the initial setting, the voltage change ΔV is 0.1 V, the maximum voltage Vmax is 5.3 V, the minimum voltage Vmin is 4.7 V, and the maximum number of times of measurement Tm is 1,0.
Set to 0,000 times. The head number H and the maximum head number Hm are also set. Next, in step 42, the head number is designated as H = 0. In step 43, the voltage value V to be measured first is set to 4.7V. In step 44, the number of measurements is reset to T = 0. In step 45, the measurement data previously recorded on the magnetic recording medium 16 is read. In step 46, it is checked whether the read measurement data matches the previously recorded data. If they do not match, it is judged as a read error and the process proceeds to step 47, where one value of the error rate Ev is added. At step 48, the number of times of measurement T is incremented by one. In step 49, the number of measurements T is the maximum number of measurements Tm defined in step 41.
It is determined whether or not (1,000,000) is exceeded. If Tm has not been reached, the process returns to step 45 and Tm
Repeat the measurement until you reach. When the maximum number of times of measurement Tm is reached, the measurement of the error rate at the voltage value of 4.7 V is completed. Next, in step 50, the voltage value V is changed to V
= V + 1 (4.7 + 0.1 = 4.8V), voltage value 4.8
Start measuring the error rate at V. In this way, the voltage V = 4.7V to 5.3V is measured at intervals of 0.1V by 1,000,000 times to count errors. In step 51, it is determined whether the voltage V has reached 5.3V. In step 52, the head number H is set to H = H + 1 and the next head is moved to, similarly, the error rate is measured. In step 53, the head number is the maximum head number Hm
When it reaches, the processing is ended.

When the series of measurement in the above flow chart is completed, the result is stored in the configuration table 20 in step 54. The measurement results when the two head numbers are 0 and 1 are as shown in Table 2.

As shown in Table 2, for the magnetoresistive head 17 with head number 0, the power supply voltage of 5.0 V is the optimum power supply voltage because the error rate is the smallest. For the magnetoresistive head 17 having the head number 1, 4.9V is the optimum power supply voltage with the smallest error rate. FIG. 7 shows an example of measuring the error rate when the power supply voltage of the data storage device of this embodiment is changed from 5.00 V to 5.70 V in increments of 0.05 V. The horizontal axis represents the power supply voltage V, and the vertical axis represents the error rate Er. Curve A
Shows the error rate Er of the head number 0, and the curve B shows the error rate Er of the head number 1.

As described above, each magnetoresistive head 1
The optimum power supply voltage value for 7 is measured in advance at the time of factory shipment before being shipped to the user and stored in the configuration table 20, and when the user uses it, the most error is based on the value of the configuration table 20. Be able to use it with less power supply voltage. The area of the magnetic recording medium 16 in which the test pattern for error rate measurement used for the factory shipment is recorded can be erased by the format and used as a data zone after the measurement is completed, so that the data capacity is not reduced. Absent. FIGS. 8 and 9 show an example of a recording unit of error rate measurement data recorded on the magnetic recording medium 16 in the data storage device of the fifth embodiment.

The magnetic recording medium 16 usually has a plurality of circular tracks from the inner circumference to the outer circumference. FIG. 8 is a diagram showing a plurality of arc-shaped tracks D in one part of a circle in a short form. Each track n, n + 1, n + 2 ... Has a servo area A and a data area B. Measurement data for measuring an error rate is recorded in an area 66 outside the track n of the magnetic recording medium 16, for example. Further, as shown in FIG. 9, the error rate measurement data may be recorded in the area 67 between the data area B and the servo area A of the magnetic recording medium 16.

[0065]

As described in detail in the above embodiments, according to the data storage device of the present invention, the position of the head on the magnetic disk, the fluctuation of the characteristics of the magnetoresistive head,
The regenerative amplifier can always be kept in the best state by switching the input part of the regenerative amplifier to either the differential end or the single end according to the fluctuation of the amplifier characteristics due to the power supply voltage, the change of the head resistance, and the recording frequency. it can. Even if the environment fluctuates during use, the input section of the regenerative amplifier can be optimized to prevent fluctuations in performance due to aging of the device. Further, since it is possible to secure a larger margin for product design at room temperature, the yield of products is improved and the reliability is also improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the configuration of a magnetoresistive head amplifier according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a data storage device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a data storage device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a data storage device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing the configuration of a data storage device according to a fifth embodiment of the present invention.

FIG. 6 is a flowchart showing a processing flow of a fifth embodiment.

FIG. 7 is a graph of the error rate of the magnetic recording medium of the fifth embodiment.

FIG. 8 is a plan view of a disk showing an error measurement pattern area of the magnetic recording medium of the fifth embodiment.

FIG. 9 is a plan view of a disk showing another example of the error measurement pattern area of the magnetic recording medium of the fifth embodiment.

[Explanation of symbols]

1 First bias circuit 2 First switch 3 Second bias circuit 4 Second switch 5 First stage amplifier circuit 6 Magnetic recording media 7 Magnetoresistive head 8 Magnetoresistive head amplifier 10 buffers 11 Terminal judgment section 12 Control signal line 13 Amplifier termination switching unit 14 Area detector 15 format table 16 Head resistance measurement unit 17 Head resistance table 18 lead channels 19 Position information detector 20 configuration table 21 Voltage determination unit 22 Voltage value indicator 23 Voltage value change unit

Claims (19)

[Claims] 1. A first bias circuit which is connected to a first terminal of a magnetoresistive head element and supplies a bias current, and a first input terminal is connected to a first terminal of the head element. A two-input amplifier circuit, a second terminal of the head element is connected, a first switch for selecting a connection destination of the second terminal from a circuit ground and a second bias circuit, and the first switch through the first switch A second bias circuit for supplying a bias current to the second terminal of the head element and a second input terminal of the two-input amplifier circuit are selected as either the second terminal of the head element or a reference voltage source. A magnetoresistive head amplifier having a second switch that is connected and is interlocked to select a second terminal of the head element when the first switch is selecting the second bias circuit. . 2. The first switch is a two-way switching type switch, and when switching in the first direction, the second terminal of the head element is connected to the second bias circuit,
2. The magnetoresistive head amplifier according to claim 1, wherein the second terminal is controlled so as to be connected to the circuit ground at the time of switching to the direction. 3. The second switch is a two-way switch, and when switching to the first direction, the second terminal of the head element and the input end of the amplifier circuit are connected to each other to provide a second switch. 2. The magnetoresistive effect head amplifier according to claim 1, wherein at the time of switching to the direction, the input terminal of the amplifier circuit is controlled to be connected to a reference voltage source. 4. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. Effect type head, magnetoresistive effect head amplifier for amplifying and outputting the read signal output from the magnetoresistive effect head, and a position for recognizing the position of the magnetoresistive effect head on the magnetic recording medium. Information detecting section, a buffer storing data array information recorded in the magnetic recording medium, position information in the direction along the track of the magnetic recording medium obtained from the position information detecting section, data obtained from the buffer Compared with the array information, the input portion of the magnetoresistive head amplifier is either a differential end type or a single end type. Is set to the differential end type, and an input terminal of the magnetoresistive head amplifier is set to a differential end type by a terminal end determination section that outputs a control signal indicating a determination result, and a control signal output from the terminal end determination section. A data storage device having an amplifier termination switching unit for switching to either a single end type or a single end type. 5. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. Effect head, magnetoresistive head amplifier for amplifying and outputting the read signal output from the magnetoresistive head, position information for recognizing the position of the magnetoresistive head on a magnetic recording medium A detection unit, a buffer storing data array information recorded on the magnetic recording medium, a data array obtained from the buffer with position information in the direction along the track of the magnetic recording medium obtained from the position information detecting unit Compared with the information, the input part of the magnetoresistive head amplifier can be either a differential end type or a single end type. The end of the magnetoresistive head amplifier by a differential end type or a control signal output from the end determination unit that outputs a control signal indicating the determination result. A method of reproducing data in a data storage device having an amplifier termination switching unit for switching to one of a single end type, wherein when reproducing data of a track in an inner peripheral portion of a magnetic recording medium, The input part of the head amplifier is set to a single end type, and when reproducing the data of the track on the outer peripheral part, the input part of the magnetoresistive head amplifier is set to the differential end type and recorded on the magnetic recording medium. How to replay existing data. 6. A step of recording and storing data on a magnetic recording medium, and reading according to a resistance value between both terminals of a magnetoresistive head which changes by detecting information recorded on the magnetic recording medium. Outputting a signal, amplifying and outputting the read signal output from the magnetoresistive head, and recognizing the position of the magnetoresistive head on the track of the magnetic recording medium from the read signal Storing a data array information recorded in advance on the magnetic recording medium in a buffer, comparing information on a position on a track of the magnetic recording medium with data array information obtained from the buffer to obtain a magnetoresistive effect. Type differential amplifier or single-ended type for the input section of the head amplifier A step of instructing the input part of the magnetoresistive head amplifier to select either a differential end type or a single end type based on the judgment result, and the magnetoresistive head. A data reproducing method for a data storage device, which comprises a step of switching an input section of a differential amplifier to a differential end type or a single end type, wherein the magnetoresistive head amplifier is used in a track of a predetermined inner peripheral portion of a magnetic recording medium. Is set to a single end type, and the input section of the magnetoresistive head amplifier is set to a differential end type in a predetermined track on the outer peripheral side to reproduce the data recorded on the magnetic recording medium. Data recording medium recording method. 7. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. Effect head, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and a track on the magnetic recording medium surface of the magnetoresistive head from the read signal Area detection unit for recognizing the position along the direction, a buffer storing data array information recorded in advance on the magnetic recording medium, data array obtained from the buffer position information obtained from the area detection unit Compared with the information, the input part of the magnetoresistive head amplifier is of the differential end type or the single end type. Which of the differential end type and the single end type the input portion of the magnetoresistive head amplifier is determined according to the terminal signal determining portion that outputs a control signal indicating the determination result and the control signal. A data storage device having an amplifier termination switching unit for switching to or from. 8. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. The position of the magnetoresistive head, the magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, and the position of the magnetoresistive head along the track on the magnetic recording medium. An area detection unit for recognition, a buffer in which data array information of servo areas and data areas recorded in advance on tracks of the magnetic recording medium is stored, position information obtained from the area detection unit and obtained from the buffer And comparing the data array information with the data array information, the input portion of the magnetoresistive head amplifier is set to the differential end type or the single end type. End type determination unit which determines which of the two types is to be set and outputs a control signal indicating the determination result, and the input unit of the magnetoresistive head amplifier for the differential end type or single end type by the control signal. A method of reproducing data in a data storage device having an amplifier termination switching unit for switching to any one of the following, wherein in a servo area of a track of a magnetic recording medium, the input unit of the magnetoresistive head amplifier is a single-ended type. A method of reproducing the data recorded on the magnetic recording medium by setting the input portion of the magnetoresistive head amplifier in the data area to the differential end type. 9. A step of recording and storing data on a magnetic recording medium, and reading according to a resistance value between both terminals of a magnetoresistive head which changes by detecting information recorded on the magnetic recording medium. Outputting a signal, amplifying the read signal output from the magnetoresistive head with an amplifier for a magnetoresistive head, and outputting the read signal, along a track on the magnetic recording medium surface of the magnetoresistive head Recognizing the position in the direction, storing in a buffer the data arrangement information of the servo area and the data area recorded in advance on the track of the magnetic recording medium, the position information obtained from the area detection unit and the information obtained from the buffer The input section of the magnetoresistive head type amplifier is compared with the differential array data by comparing it with the data array information. A step of determining which of the differential type or the single end type is set, a step of instructing whether the input end of the magnetoresistive head amplifier is a differential end type or a single end type, and In a data reproducing method of a data storage device, which comprises a step of switching an input part of a magnetoresistive head type amplifier to either a differential end type or a single end type, in the servo area of the magnetic recording medium, the magnetoresistive head A method for reproducing data recorded on a magnetic recording medium by setting the input section of the amplifier for a single end type and setting the input section of the magnetoresistive head type amplifier for the differential end type in the data area is recorded. Data description Recording medium. 10. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. Magnetoresistive head, magnetoresistive head amplifier for amplifying and outputting the read signal output from the magnetoresistive head, head resistance value measuring unit for measuring the resistance value of the magnetoresistive head, the magnetic A head resistance value table that is a memory that stores the threshold value of the resistance value of the resistance effect type head, and head resistance value information obtained from the head resistance value measuring unit,
Comparing with the information obtained from the head resistance value table,
It is determined whether the input unit of the magnetoresistive head type amplifier is set to a differential end type or a single end type, and a terminal end determination unit that outputs a control signal indicating the determination result, and the control signal, A data storage device comprising an amplifier termination switching unit that switches an input unit of a magnetoresistive head amplifier to either a differential end type or a single end type. 11. A plurality of magnetoresistive heads for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on a magnetic recording medium, and the plurality of magnetoresistive heads. A head resistance value measuring unit for measuring each resistance value of the effect head is provided, and the input unit of the magnetoresistive effect head amplifier is set to either a differential end type or a single end type according to the resistance value. Claim 1 characterized by the above.
0 data storage device. 12. A magnetic recording medium for recording and storing data, wherein a plurality of read signals are output according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. A magnetoresistive head, a magnetoresistive head amplifier for amplifying and outputting the read signal output from the magnetoresistive head, a head resistance measuring unit for measuring the resistance of the magnetoresistive head, A head resistance value table that stores the threshold value of the resistance value of the magnetoresistive head, comparing the head resistance value information obtained from the head resistance value measuring unit with the information obtained from the head resistance value table, It is determined whether the input portion of the magnetoresistive head amplifier is set to the differential end type or the single end type, and the determination result Data having a terminal end determination section that outputs a control signal that represents, and an amplifier terminal switching section that switches the input section of the magnetoresistive head amplifier to either a differential end type or a single end type according to the control signal. A data reproducing method of a storage device, wherein the resistance value of the magnetoresistive head measured by the head resistance value measuring unit is compared with a threshold value stored in the head resistance value table, and the resistance value is compared. When amplifying the read signal of the magnetoresistive head whose value exceeds the threshold value, the input section is set to the differential end type, and the read signal of the magnetoresistive head whose resistance value is equal to or less than the threshold value is amplified. In this case, the data reproducing method is characterized in that the input section is set to a single end type. 13. A magnetic recording medium for recording and storing data, and a plurality of read signals according to a resistance value between both terminals, which is changed by detecting information recorded on the magnetic recording medium. A magnetoresistive head, a magnetoresistive head amplifier that amplifies and outputs the read signal output from the magnetoresistive head, a head resistance measuring unit that measures the resistance of the magnetoresistive head, A head resistance value table that stores the threshold value of the resistance value of the magnetoresistive head, comparing the head resistance value information obtained from the head resistance value measuring unit with the information obtained from the head resistance value table, It is determined whether the input portion of the magnetoresistive head amplifier is set to the differential end type or the single end type, and the determination result A terminal determination section that outputs a control signal that represents, a data storage having an amplifier termination switching section that switches the input section of the magnetoresistive head amplifier to either a differential end type or a single end type according to the control signal. A method of reproducing data in an apparatus, wherein the resistance value measured by the head resistance value measuring unit is 5
When amplifying the read signal of the magnetoresistive head exceeding 5 ohms, select the differential end type input section and amplify the read signal of the magnetoresistive head whose resistance value is 55 ohms or less. A data reproducing method for a data storage device, comprising selecting a single-ended type input unit. 14. A step of recording and storing data on a magnetic recording medium, and reading according to a resistance value between both terminals of a magnetoresistive head which changes by detecting information recorded on the magnetic recording medium. A step of outputting a signal; a step of amplifying and outputting the read signal output from the magnetoresistive head by a magnetoresistive head amplifier; a step of measuring a resistance value of the magnetoresistive head; A step of storing the threshold value of the resistance value of the resistance effect type head in a resistance value table, comparing the head resistance value information obtained from the head resistance value measuring unit with the information obtained from the head resistance value table, and the magnetoresistive effect Type head amplifier input section is a differential end type or single end type. A step of instructing whether the input section of the magnetoresistive effect head amplifier is a differential end type or a single end type according to the determination result, and the magnetoresistive effect head amplifier according to the instruction In a method of controlling a data storage device having a step of switching an input unit to either a differential end type or a single end type, the resistance value of the magnetoresistive head measured by the head resistance value measuring unit is set to the head resistance value. When amplifying the read signal of the magnetoresistive head in which the resistance value exceeds the threshold value compared with the threshold value obtained from the table memory, the input unit is set to the differential end type, and the resistance value is equal to or less than the threshold value. When the read signal of the resistance effect head is amplified Data recording medium that records the control method for making the input section a single-ended type. 15. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. Effect type head, magnetoresistive effect head amplifier for amplifying the read signal output from the magnetoresistive effect head and outputting a differential analog signal, differential output from the magnetoresistive effect head amplifier A read channel unit that converts an analog signal into digital data, an error rate measurement unit that calculates an error rate from digital data obtained from the read channel unit, and a memory that stores the result of the error rate measured by the error rate measurement unit. Configuration table having, data of the configuration table For the magnetoresistive head according to the voltage value determined by the voltage deciding unit that refers to the optimum voltage value to be supplied to the first stage amplifier of the magnetoresistive effect head amplifier, and the voltage deciding unit. A data storage device comprising: a voltage value changing unit that changes the value of the voltage supplied to the first-stage amplifier of the amplifier. 16. The data storage device according to claim 15, wherein the voltage value changing unit is included in the magnetoresistive head amplifier. 17. A magnetoresistive head having a voltage value changing unit capable of changing the value of a voltage supplied to each of the magnetoresistive head amplifiers corresponding to a plurality of magnetoresistive heads. 16. The data storage device according to claim 15, wherein the data storage device is provided in a power amplifier. 18. A magnetic recording medium for recording and storing data, and a magnetic resistance for outputting a read signal according to a resistance value between both terminals which changes by detecting information recorded on the magnetic recording medium. Effect type head, magnetoresistive effect head amplifier that amplifies the read signal output from the magnetoresistive effect head and outputs a differential analog signal, differential output from the magnetoresistive effect head amplifier A read channel unit that converts an analog signal into digital data, an error rate measurement unit that calculates an error rate from the data obtained from the read channel unit, and a memory that stores the error rate result measured by the error rate measurement unit Configuration table, refer to the data in the configuration table A voltage determining unit that indicates an optimum voltage value to be supplied to the first-stage amplifier of the magnetoresistive head amplifier, a voltage supplied to the magnetoresistive head amplifier according to the voltage value determined by the voltage determining unit A method of reproducing data in a data storage device having a voltage value changing unit for changing the value of, wherein the voltage value changing unit changes the value of the voltage supplied to the magnetoresistive head amplifier stepwise, A data reproducing method for obtaining an error rate for each voltage value that has been changed, and supplying the voltage at the lowest error rate to the timing resistance effect head amplifier. 19. A step of recording and storing data on a magnetic recording medium, and reading according to a resistance value between both terminals of a magnetoresistive head which changes by detecting information recorded on the magnetic recording medium. Outputting a signal; amplifying the read signal output from the magnetoresistive head by a magnetoresistive head amplifier and outputting the read signal; changing a voltage value supplied to the magnetoresistive head amplifier A step of converting the differential analog signal output from the magnetoresistive head amplifier to digital data, a step of calculating an error rate based on the digital data, and a calculation result of the error rate in a memory. Storing in a configuration table, the configuration In a method of controlling a data storage device, which comprises a step of deciding an optimum voltage value by a voltage deciding unit by referring to the table data and instructing it, a value of a voltage supplied to the magnetoresistive head amplifier is changed stepwise. Then, an error rate for each stepwise changed voltage value is obtained, and the voltage at the lowest error rate is supplied to the timing resistance effect type head amplifier.