JP2000235701A - Bias current control method of magnetic resistance head, and fixed magnetic recorder and magnetic disk thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bias current control method of a magnetic resistance head for reducing an error rate at the time of reading out data and a fixed magnetic recorder and a magnetic disk thereof by executing the optimization of the bias current of the MR head in the operating process of the fixed mag netic recorder and suppressing the asymmetrical distortion due to the saturation of the waveform of a reproduced signal from the MR head. SOLUTION: The fixed magnetic recorder is provided with an optimizing measurement means 10 for executing the measurement to optimize the bias current value of the MR head for every access time of the MR head of a head constituting part 1 to a magnetic disk 2 and a microcomputer 8 for updating the bias current value of the MR head to the measured optimum bias current value for storage by controlling the optimizing measurement means 10 and for outputting the instruction to supply the updated and stored optimum bias current value to the MR head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a bias current of a magnetoresistive head utilizing a magnetoresistance effect, a fixed magnetic recording apparatus, and a magnetic disk thereof.

[0002]

2. Description of the Related Art In recent years, most of fixed magnetic recording devices (HDDs: hard disk drives) employ MR (magnetoresistive) heads in accordance with the demand for recording density which is increasing year by year.
The MR head is a reproducing method using the so-called magnetoresistance effect, the electric resistance of which is changed by an external magnetic field.
Some HDDs use a combined MR / inductive head in which an MR head and a thin film head are integrally combined. This MR / inductive combined type head writes data using a thin film head,
Data is read using an MR head arranged adjacent to the thin film head. Therefore, although the MR head is read-only, the reproduction output obtained is larger than that of the thin-film head, and since the reproduction output does not depend on the peripheral speed of the magnetic disk, the track width read from the thin-film head for writing is reduced. By doing so, there is an advantage that the influence of adjacent tracks during reading can be reduced. Therefore, it is widely used as a current HDD head. GM with improved sensitivity of MR element
R (giant magnetoresistive) heads are also being put to practical use.

However, the MR head requires a bias current due to its operation principle, and if the bias current is not controlled optimally, there is a problem that the reproduced signal waveform is distorted. This is caused by either the positive or negative of the reproduced signal waveform being saturated due to the shift of the bias point due to the bias current. In this case, the reproduced signal waveform becomes positive and negative and asymmetric.

In order to optimally control the bias current of the MR head, it is necessary to solve the following three problems. The first problem is variation in head resistance due to dimensional variation in the MR head. MR
Although head dimensions are becoming smaller and smaller, the tolerance for dimensional variations has not improved as fast as the dimensions themselves. According to recent device design examples, variation with MR stripe height allows a +/- 33% change, with a 2: 1 ratio for the highest to lowest ratio. Further, the variation in the width (length in the direction of current) of the MR stripe is +
/ -20%. MR stripe thickness tolerance is +
/ −10%. If these are considered independent variations, the overall variation in the resistance of the element will be about +/-
A height ratio of 40%, or 2.33: 1.

When the head resistance values of a plurality (for example, 80) of MR heads are actually measured, as shown in FIG.
It can be seen that the head resistance varies. The horizontal axis indicates the head resistance value, and the vertical axis indicates the number. The variation distribution of the head resistance value is a normal distribution centering on the design value, but the resistance value of the sensor section is different in each MR head.

[0006] Problems due to large dimensional variations will affect large differences in power consumption when there are various heads in a single device. Furthermore, when the cross section (MR stripe height x thickness) with respect to the current changes significantly, the current density also changes in conjunction with it. Product life is inversely related to the cube of current density.
Since the normal biasing method uses a constant DC current for all heads, low stripe heights and thin layer thicknesses result in high resistance and high current density. The resulting power consumption is much higher than that with high and thick stripes,
That is, heat is generated. Therefore, the temperature and current density are
The average lifetime can be much shorter for low and thin MR elements with low stripe height than for high and thick elements.

Another possibility is that any element that increases the resistance will also increase the signal level. Therefore, the best signal-to-noise ratio is to choose the head with the highest resistance. Thus, low stripe heights, thin layers, and wide width stripes can produce good signal-to-noise ratios, while high, thick, narrow stripes have poor signal-to-noise ratios. Occurs. Therefore, a constant bias current must compromise between good signal and short lifetime.

A change in output when a bias current value is changed for a plurality (for example, four) of MR heads has a waveform as shown in FIG. Since the current becomes the optimum bias current at the time of reading, it can be seen that the optimum bias current characteristic at the time of reading differs for each head. 2
The second problem is that a good electronic signal to noise ratio depends on the design of the preamplifier circuit. The preamplifier design was designed to reduce the power supply voltage to the available preamplifier circuit, or to reduce the target power consumption.
Has major restrictions. Current designs typically have a single +5 volt power supply (+/- 5%). Fluctuations in the resistance of the head also limit the operable bias current value due to the voltage drop caused by the head and the leads. If excessively large current flows through the high resistance head, the preamplifier stage may saturate and distort the signal, leading to reduced performance.

A third problem is a gradual increase in resistance (GRIP) of the leads in the MR head. If the resistance of the MR head increases by several ohms over the lifetime of the fixed magnetic recording device, the effect on performance will be greater than expected. Thus, too little design margin in manufacturing can induce pre-amplifier saturation when resistance increases over the life of the product, resulting in significant performance loss.

In order to solve the above three problems, a conventional HDD disclosed in Japanese Patent Application Laid-Open No. 7-201005 is generally known. This HD
D denotes a plurality (for example, four) of MR heads 31a to 31d, a preamplifier 32, and a GEM as shown in FIG.
(Generalized Error Measurement) 33, a head / disk assembly controller 34, and a microprocessor 35. In this HDD, the optimum bias current value of each head is stored on the disk surface at the time of manufacture, and when the power is turned on, these values are transferred to a random access memory, and the random access memory is executed when each head switching command is executed. The bias current is applied to the active MR head as a memory, the MR head is measured, the bias current is reoptimized and updated by the GEM 33, and the updated bias current is applied to the MR head.

The measurement of the MR head is realized by the circuit shown in FIG. For example, when measuring the MR head 31a, only the switches 36a and 37a are connected in a conductive state, a bias current is supplied from the feedback control circuit 40, and the measured value Vcap obtained by measuring the voltage of the capacitor 39 is obtained.
And the known bias current value Ib, the head resistance value Rmr of the MR head is calculated. This MR head resistance value Rmr
Is calculated based on the following (Equation 1).

Rmr = (Vcap−Vbe) / Ib (1) An optimum current value is determined based on the calculated head resistance value Rmr of the MR head. Thus, in the conventional HDD,
MR recorded on the disk surface at factory shipment every time the power is turned on
The bias current value is optimized based on the head resistance value of the head.

[0013]

However, in the conventional fixed magnetic recording apparatus, when the power is turned on, the bias current value is optimized based on the head resistance value of the MR head recorded on the disk surface at the time of shipment from the factory. It is not possible to cope with the head characteristics changing every moment with the passage of time. Therefore, when the MR head resistance value changes, the bias current value determined to be optimal at the time of shipment from the factory is used for a lifetime, or the bias current value determined to be optimal in the previous measurement is the next bias current value. It will be adopted until the time of periodic reoptimization update. This bias current value is not always guaranteed to be the optimum value of the current head, and the head output characteristics may deteriorate and the error rate may deteriorate. In general, the life of the head is inversely proportional to the cube of the current density. Therefore, if an excessive bias current is supplied, the average life is shortened.

Further, the determination of the life based on the resistance change is only a comparison with the guaranteed number of starts, and it is not possible to detect the presence or absence of the actual resistance change, so that there is a problem that the life cannot be accurately determined. Meanwhile, a fixed magnetic recording device using an amplitude detection type reproduction method such as a partial response that directly uses the amplitude value of a read signal for processing a signal read from a magnetic disk is becoming mainstream.
When an MR head is used in such a fixed magnetic recording device, the reproduced signal from the MR head is distorted, and the absolute values of the waveforms that should have the same positive and negative levels with respect to the baseline are different. As a result, the asymmetry of the detected amplitude of the reproduced signal becomes large. This error in the amplitude width causes a problem that the error rate of the reproduction signal read by the MR head is deteriorated and the reliability of the entire system is impaired. Also, in a fixed magnetic recording apparatus using a conventional peak detection type reproducing method, when the same distortion occurs in the reproduced signal when the MR head is used, the differential value at the peak of the reproduced signal waveform is not equal to the waveform. Since it becomes smaller on the saturated side, the influence of noise also increases, and similarly, the error rate of the reproduced signal deteriorates.

As described above, in a fixed magnetic recording apparatus using an MR head for reading data and employing a reproducing method of an amplitude detection type such as a partial response, unless the bias current of the MR head is adjusted optimally, the reproduction signal cannot be reproduced. Despite the problem that the error rate deteriorates, there has been a drawback that a method for optimally adjusting the bias current of the MR head has not been established. Even in a fixed magnetic recording apparatus using an MR head and employing a peak detection type reproducing method, unless the bias current of the MR head is adjusted optimally, the influence of noise increases and the error rate of the reproduced signal deteriorates. Therefore, there is a similar disadvantage.

According to the present invention, optimization of a bias current of an MR head can be appropriately performed during operation of a fixed magnetic recording apparatus,
An object of the present invention is to provide a bias current control method for a magnetoresistive head, a fixed magnetic recording device, and a magnetic disk for suppressing an asymmetric distortion due to saturation of a reproduction signal waveform from the MR head and reducing an error rate during data reading. .

[0017]

According to the bias current control method for a magnetoresistive head of the present invention, measurement for optimizing the bias current of an MR head is appropriately performed during the operation of a fixed magnetic recording apparatus in accordance with the operation of the MR head. Then, the bias current value of the MR head is updated and stored to the measured optimum bias current value, the stored optimum bias current is supplied to the MR head, and the data recorded on the magnetic disk is read. To read.

According to the present invention, the bias current of the MR head can be appropriately optimized during the operation of the fixed magnetic recording apparatus, the asymmetric distortion due to the saturation of the reproduction signal waveform from the MR head can be suppressed, and the error in reading data can be reduced. The rate can be reduced.

[0019]

According to the first aspect of the present invention, when controlling a bias current supplied to a magnetoresistive head for reading data recorded on a magnetic disk, the magnetoresistive head is connected to the magnetic disk. Performing a measurement for optimizing the bias current value of the magnetoresistive head each time the access is performed, updating the bias current value of the magnetoresistive head to the measured optimal bias current value, and storing the updated bias current value.
A bias current control method for a magneto-resistive head for reading the data by supplying the stored optimal bias current to the magneto-resistive head. Can be appropriately performed during the operation of the fixed magnetic recording apparatus, and even if the characteristics of the magnetoresistive head during operation change every moment over time, the optimum bias current can be maintained. Asymmetry distortion due to saturation of the reproduction signal waveform from the resistance head can be suppressed, the error rate at the time of data reading can be reduced, and the optimum bias current is supplied to the magnetoresistive head. Flowing can be prevented, and shortening of the average life due to overcurrent can be prevented.

According to a second aspect of the present invention, in controlling a bias current to be supplied to a magnetoresistive head for reading data recorded on a magnetic disk, when the magnetoresistive head enters an operation waiting state, the magnetoresistive head becomes inactive. A measurement for optimizing the bias current value of the head is performed, the bias current value of the magnetoresistive head is updated to the measured optimal bias current value and stored, and the stored optimal current value is stored in the magnetoresistive head. This is a method of controlling a bias current of a magnetoresistive head for reading the data by supplying a bias current, and has the same effect as the method of controlling a bias current of a magnetoresistive head according to the first aspect of the present invention.

According to a third aspect of the present invention, in a fixed magnetic recording apparatus for recording data on a magnetic disk and reading the data with a magnetoresistive head, each time the magnetoresistive head accesses the magnetic disk, An optimization measuring means for performing a measurement for optimizing a bias current value of the magnetoresistive head, and controlling the optimization measuring means to update the bias current value of the magnetoresistive head to the measured optimal bias current value. 2. A fixed magnetic recording apparatus according to claim 1, further comprising processing means for outputting an instruction to supply said optimum bias current updated and stored to said magnetoresistive head. The bias current control method for the magnetoresistive head described above can be realized.

According to a fourth aspect of the present invention, in a fixed magnetic recording apparatus for recording data on a magnetic disk and reading the data with a magnetoresistive head, when the magnetoresistive head is in an operation waiting state, the magnetoresistive head is not required. Controlling the optimization measuring means for executing the measurement for optimizing the bias current value of the magnetic head, and updating and storing the bias current value of the magnetoresistive head to the measured optimum bias current value. And a processing unit for outputting an instruction to supply the updated and stored optimum bias current to the magnetoresistive head. 3. The magnetoresistive device according to claim 2, wherein It is possible to realize a head bias current control method.

According to a fifth aspect of the present invention, there is provided a magnetic disk on which a control routine for operating a central processing unit for controlling a fixed magnetic recording apparatus is recorded, wherein the control routine comprises a magnetoresistive head. A first step of optimizing the bias current value of the magnetoresistive head each time the user accesses the magnetic disk, and updating and storing the bias current value of the magnetoresistive head to the measured optimum bias current value And a third step of supplying the updated and stored optimum bias current to the magnetoresistive head. The control routine is recorded on a magnetic disk. By executing the recorded control routine, the bias current value of the magnetoresistive head can be optimized.

According to a sixth aspect of the present invention, in the first step, the bias current value of the magnetoresistive head is optimized when the magnetoresistive head enters an operation waiting state. And has the same effect as the magnetic disk according to claim 5 of the present invention. The invention according to claim 7 of the present invention provides
In a fixed magnetic recording device for recording data on a magnetic disk and reading the data with a magnetoresistive head, a storage means for storing a temperature characteristic of a head resistance value of the magnetoresistive head; A fixed magnetic recording apparatus provided with a measuring means for measuring a head resistance value of the magnetoresistive head, and an arithmetic means for calculating a temperature based on the measured head resistance value,
The magnetoresistive head can be used as a temperature sensor without separately providing a temperature sensor, and the temperature can be monitored.

According to an eighth aspect of the present invention, there is provided a magnetic disk recording a control routine for operating a central processing unit for controlling a fixed magnetic recording apparatus, wherein the control routine includes a magnetoresistive head. A first step of storing a temperature characteristic of the head resistance value of the head, a second step of measuring a head resistance value of the magnetoresistive head when the head is in an operation waiting state, and a head resistance value measured as described above. And a third step of calculating the temperature based on the magnetic disk. The control routine is recorded on the magnetic disk. By executing the control routine recorded on the magnetic disk, the magnetoresistive head is used as a temperature sensor. Can be used.

According to a ninth aspect of the present invention, in a fixed magnetic recording apparatus having a plurality of magnetoresistive heads for reading data recorded on a magnetic disk, the temperature characteristics of the head resistance values of the plurality of magnetoresistive heads are determined. A storage means for storing each; a measuring means for measuring a head resistance value of the magnetoresistive head when the magnetoresistive head is in an operation waiting state; a head resistance value of the plurality of measured magnetoresistive heads and the temperature characteristic; And a predicting means for predicting the degree of characteristic deterioration of the magnetoresistive head based on the calculated temperature. Monitoring can be performed, and the life of the fixed magnetic recording device can be predicted.

According to a tenth aspect of the present invention, there is provided the fixed magnetic recording apparatus according to the ninth aspect, further comprising warning means for warning the degree of characteristic deterioration of the magnetoresistive head from the predicting means. A warning can be issued to the user.
The invention according to claim 11, wherein in the fixed magnetic recording device for recording data on a magnetic disk and reading the data with a magnetoresistive head, a protrusion is provided at a specific position on the magnetic disk. Is a fixed magnetic recording apparatus provided with monitoring means for monitoring the fluctuation of the flying height of the magnetoresistive head based on the amount of output fluctuation when passing over the protrusion. Fluctuations can be monitored and crashes can be prevented.

According to a twelfth aspect of the present invention, there is provided the fixed magnetic recording apparatus according to the eleventh aspect, further comprising a warning unit that warns when the amount of output fluctuation exceeds a threshold value. Can be warned. According to a thirteenth aspect of the present invention, there is provided a magnetic disk on which a control routine for operating a central processing unit for controlling a fixed magnetic recording apparatus is recorded, wherein the control routine includes a projection of the magnetoresistive head. A first step of measuring and storing an output fluctuation amount when passing over an object;
A magnetic disk on which this control routine is recorded, comprising a second step of determining whether or not the stored output fluctuation amount exceeds a threshold value, and a third step of issuing a warning when the stored output fluctuation amount exceeds the threshold value; By executing the control routine recorded on the magnetic disk, the fluctuation of the flying height of the magnetoresistive head can be monitored.

According to a fourteenth aspect of the present invention, the first
14. The magnetic disk according to claim 13, wherein, when the magnetoresistive head is in an operation waiting state, the amount of output fluctuation when passing over a protrusion of the magnetoresistive head is measured and stored, Claim 1 of the present invention described above.
3 has the same effect as the magnetic disk described in No. 3. Less than,
A bias current control method for a magnetoresistive head, a fixed magnetic recording device, and a magnetic disk thereof according to the present invention will be described based on specific embodiments.

(Embodiment 1) In a fixed magnetic recording apparatus according to Embodiment 1 of the present invention, as shown in FIG. 1, each time an MR (magnetic resistance) head of a head component 1 accesses a magnetic disk 2, The optimization measuring means 10 for executing the measurement for optimizing the bias current value of the MR head, and the optimization measuring means 10 are controlled, and the bias current value of the MR head is updated to the measured optimum bias current value. And a microcomputer 8 as processing means for outputting an instruction to supply the updated bias-optimized bias current to the MR head.

The optimization measuring means 10 comprises a magnetic disk 2, a preamplifier 3, a data channel 4, a GEM 5, a hard disk controller 6, and a buffer 7. As shown in FIG. 2, the magnetic disk 2 usually has a plurality of circumferential tracks from the inner circumference to the outer circumference, and each track has a plurality of servo areas A and data areas B.
When reading or writing data by accessing the data area B by the MR head, be sure to read and confirm the position information written in the servo area A and then access the desired location. To do
In the magnetic disk 2 of the first embodiment, a measurement pattern area C (an area between the servo area A and the first data which is the first data of the data area B) is provided immediately after all the servo areas A. In the measurement pattern area C, a measurement pattern for measuring a signal-to-noise ratio for optimizing a bias current value is formed. Regardless of which data area B is accessed, the measurement pattern area C is always accessed and passed through the measurement pattern before the data in the data area B is read or written. As shown in FIG. 3, a plurality of identical measurement patterns are formed on any track. As shown in FIG. 4, a signal having a certain periodicity is written and recorded in the measurement pattern area C at the time of shipment from the factory. The signal having the constant periodicity is a signal indicated as precode data in a pattern having one cycle of 1 to 127 T (T is a time determined by the performance of the MR head, for example, 5 ns). is there.

The head structure 1 has an MR head and is connected to a line leading to the preamplifier 3. The output of the preamplifier 3 is supplied to a data channel 4. The addressed MR head is connected to a bias current source (not shown) by setting the respective switches shown in FIG. The GEM 5 has a general-purpose error measurement function and performs measurement of a signal-to-noise ratio, and is realized by connecting a measurement test system data storage device such as a conventional digital oscilloscope and a logic analyzer and a recovery system. The test system is designed so that it can be executed on-board by the fixed magnetic recording apparatus itself.

The buffer 7 stores the optimum bias current value of each MR head at the time of shipment from the factory, and 1 to 127 shown in FIG.
An ideal signal waveform obtained by sampling the precode data having T as one cycle and standardizing the sampled data is stored in advance.
Here, an operation of updating the bias current value of the MR head to the optimum bias current value in the fixed magnetic recording device will be described.

The hard disk controller 6 issues an instruction to access the magnetic disk 2 to the microcomputer 8
, The head structure 1 having the MR head is controlled so as to access a desired position of the magnetic disk 2 rotating at a high speed. When the MR head accesses the desired servo area A of the magnetic disk 2 and then accesses the measurement pattern area C, a current source (not shown) for supplying a bias current to the MR head is set to, for example, 7 mA and supplied to the MR head. , GEM5, and compares the level difference between the actual reproduced waveform as shown in FIG. 5 from which the measurement pattern is read out and the standardized ideal signal waveform stored in the buffer 7 for one cycle (1 to 127T). Analyze to calculate the signal-to-noise ratio. Next, the signal-to-noise ratio is calculated in the same manner as described above with the current source set to 8 mA. Thus, the current source is set to 1
The signal-to-noise ratio is calculated in the same manner as described above until the current reaches 1 mA. The change in the signal-to-noise ratio with respect to the change in the bias current has a waveform having a peak as shown in FIG.

Specifically, the signal-to-noise ratio for each actually measured bias current value is 25 dB when the current source is 7 mA, 26 dB when the current source is 8 mA, and 9 mA when the current source is 8 mA. Signal-to-noise ratio of 26.8
dB, signal-to-noise ratio 27 dB at the time of the current source 10 mA,
Assuming that the signal-to-noise ratio at the time of the current source 11 mA is 26.9 dB and the waveform is a, the bias current value when the signal-to-noise ratio is the largest is the optimum bias current value. 8 judges that 10 mA is the optimum bias current value.

In this MR head, the bias current is measured in the range of 7 mA to 11 mA.
Stores the optimum bias current of the MR head at the time of shipment from the factory, or at least the optimum bias current of the previous measurement if measurement has been performed before. Since the bias current value is stored as 9 mA, for example, ± 2 around 9 mA
The actual reproduced waveform is measured within the range of mA.

The microcomputer 8 calculates the optimum bias current value (9 mA) stored in the buffer 7.
Is updated to a new optimum bias current value (10 mA). The microcomputer 8 updates the new optimum bias current value (10 mA) that has been updated and recorded with the MR.
Instruct the head to supply.

With such a configuration, the bias current of the MR head can be optimized during the operation of the fixed magnetic recording apparatus in accordance with the operation of the MR head, and the characteristics of the MR head during the operation can be changed with time. Even if it changes, the optimal bias current can be maintained,
Asymmetry distortion due to saturation of the reproduction signal waveform from the MR head can be suppressed, the error rate at the time of data reading can be reduced, and an optimum bias current is supplied to the MR head. This can prevent the average life from being shortened by the overcurrent.

In the first embodiment, the microcomputer 8 is provided with a control routine for operating the fixed magnetic recording apparatus so as to control the fixed magnetic recording apparatus. A first step of optimizing a bias current value; a second step of updating and storing the bias current value of the MR head to the measured optimum bias current value; and
The control routine consisting of the third step of supplying the updated and stored optimal bias current to the head is recorded in diskware (DISKWARE) for storing the program of the magnetic disk 2 or recorded in the buffer 7. Even if it does, the same effect is obtained.

(Embodiment 2) As shown in FIG. 7, a fixed magnetic recording apparatus according to Embodiment 2 of the present invention replaces the optimized measuring means 10 of Embodiment 1 with an MR (magnetic resistance). When the head is in the operation waiting state, an optimization measuring means 11 for executing a measurement for optimizing a bias current value of the MR head is provided, and the measurement pattern area C of the first embodiment is formed on the magnetic disk 12. No measurement pattern is provided.

The optimization measuring means 11 comprises a plurality (for example, two) of preamplifiers 3a and 3b, a data channel 4, a GEM 13, a hard disk controller 14, and a buffer 15. The head structures 1a and 1b having the MR head are provided with any of the preamplifiers 3a and 3b.
It is configured so that it can also be connected. Preamplifier 3
The outputs of a and 3b are supplied to data channel 4.
The addressed MR head is connected to a current source (not shown) for supplying a bias current by setting the respective switches shown in FIG.

The GEM 13 has a general-purpose error measurement function.
A test system for measuring the R head resistance value Rmr, which is realized by connecting a measurement test system data storage device and a recovery system such as a conventional digital oscilloscope and a logic analyzer, to an on-board test system It is designed so that it can be executed by the fixed magnetic recording device itself.

The buffer 15 previously stores the optimum bias current value of each MR head at the time of shipment from the factory. MR
The optimal bias current for the head is set, for example, as a function of the MR head resistance. Here, an operation of updating the bias current value of the MR head to the optimum bias current value in the fixed magnetic recording device will be described.

Normal data is transmitted from the head structure section 1a through the preamplifier 3a, and when the head structure section 1b is in an operation waiting state, the hard disk controller 14
Controls the preamplifier 3b to be connected to the head structure 1b in response to an instruction from the microcomputer 8.
The measurement of the MR head is performed by using a BHV (Buffered H) of the preamplifiers 3a and 3b arranged near the head structures 1a and 1b.
ead Voltage Monitor) terminal, the voltage value between heads V
Mr is detected.

The hard disk controller 14 calculates the MR head resistance value Rmr based on the following (Equation 2). However, the current value Ib from the current source supplied to the MR head is known as a fixed current value. Rmr = Vmr / Ib (Equation 2) In the hard disk controller 14, the optimum bias current value Ib corresponding to the head resistance value Rmr of the MR head is statistically determined and the optimum bias current value Ib is determined according to the corresponding characteristic shown in FIG. The bias current value Ib is determined. The signal from the BHV terminal is an analog output.
Converts an analog signal into a digital signal.

Specifically, the current value I from the current source is set to 9 mA, and the voltage value Vm detected at the BHV terminal is Vm.
Assuming that r is 0.3 V, the head resistance value Rmr of the MR head is calculated to be about 33.3 Ω based on (Equation 2) described above, and the head resistance value Rmr of the MR head (about 3
3.3 Ω) is within the range of 30 to 35 Ω, so that the optimum bias current value Ib is set to 9.9 according to the corresponding characteristics shown in FIG.
Determine 5 mA. This optimum bias current value (9.5
mA) is, for example, 4-bit serial data (001).
0) is stored in the buffer 15.

In the head structure 1b, 4-bit serial data (0010) is sent and set, and in a normal operation state, an optimum bias current value (9.5 mA) is set to MR.
Supplied to the head. When the head structure 1b enters a normal operation state and the head structure 1a enters an operation waiting state,
The hard disk controller 14 controls to connect the preamplifier 3b to the head structure 1b in response to an instruction from the microcomputer 8, and optimizes the bias current of the MR head of the head structure 1a as described above. .

In the current fixed magnetic recording apparatus, the system logically manages sectors, and performs reading and writing for each sector. However, it is not necessary for the user to pay attention to which MR head is physically accessed to which sector, depending on the design of the drive.
At present, the time required for head switching is shorter than the time required for track seek in many cases. Therefore, when writing to one sector and then moving to the next sector, head switching is often given priority. That is, the switching of the MR head is frequently performed.

With this configuration, the bias current of the MR head can be optimized while the MR head is in an operation waiting state, and the bias current can be optimized even when the MR head characteristics during operation change every moment with time. Bias current can be maintained, the asymmetric distortion due to the saturation of the reproduction signal waveform from the MR head can be suppressed, the error rate at the time of data reading can be reduced, and the optimum bias current for the MR head can be reduced. Since the supply is performed, it is possible to prevent the bias current from flowing more than necessary, and to prevent the average life from being shortened by the overcurrent.

Further, the measurement pattern area C for forming the measurement pattern as in the first embodiment can be made unnecessary on the magnetic disk 12. In the second embodiment, the microcomputer 8 is provided with a control routine for operating the fixed magnetic recording apparatus so as to control the fixed magnetic recording apparatus.
A first step of optimizing the bias current value of the R head, a second step of updating and storing the bias current value of the MR head to the measured optimum bias current value, and A case where the control routine constituted by the third step of supplying the updated and stored optimum bias current is recorded in diskware (DISKWARE) for storing the program of the magnetic disk 12 or in a case where the control routine is recorded in the buffer 15 Has the same effect.

In the second embodiment, a plurality of preamplifiers are provided. However, even when the preamplifier is singular, the MR head does not access the magnetic disk 12 in an operation waiting state. The optimum bias current value can be set by measuring the head resistance value of the head. (Embodiment 3) In a fixed magnetic recording apparatus according to Embodiment 3 of the present invention, as shown in FIG. 9, the buffer 15 of Embodiment 2 also stores the temperature characteristics of the head resistance value of the MR head. As the buffer 16, the microcomputer 8 of the second embodiment described above is replaced with a microcomputer 17 to which an arithmetic function for calculating a temperature based on a measured head resistance value is added.

The buffer 16 stores the temperature characteristics of the head resistance value of each MR head. Although the head resistance value of the MR head differs depending on the design of the MR element, looking at the change in the head resistance value due to the temperature change of a plurality of (for example, six) MR heads, the temperature-dependent characteristic of the head resistance is As shown in FIG. 10, it changes almost linearly with temperature, and it can be seen that linear approximation is possible. The temperature gradient of the head resistance value is known at the time of design.

For example, the temperature gradient of a certain model is 0.15Ω.
/ ° C. It is assumed that the head resistance value is 25Ω during the shipping inspection process at a constant temperature of 20 ° C. The head resistance value at a known temperature at the time of shipment is stored in the buffer 16. The relationship between the head resistance value and the temperature is as shown in FIG. Here, an operation of measuring the head resistance value of the MR head and performing temperature management in the fixed magnetic recording device will be described.

As in the second embodiment, when the MR head of the head structure 1b enters the operation waiting state, the hard disk controller 14
The preamplifier 3b is connected to the head structure 1b
And the voltage value Vmr between the heads is measured at the BHV terminal of the preamplifier 3b. The current value Ib from a current source (not shown) supplied to the MR head is a fixed current value. Therefore, based on the above (Equation 2), M
The R head resistance value Rmr is calculated.

The microcomputer 17 calculates the temperature based on the measured head resistance value. For example, if the measured head resistance is 26.5Ω, the microcomputer 17 calculates that the temperature is 30 ° C. based on the temperature dependence of the head resistance shown in FIG.

When the MR head of the head structure section 1a is put into the operation waiting state instead of the head structure section 1b, the hard disk controller 14 controls the preamplifier 3a to be connected to the head structure section 1a. Then, the head resistance value is measured to calculate the temperature. Since the switching of the MR head is frequently performed, the head resistance value of the MR head is frequently measured and the temperature is calculated.

With this configuration, the temperature can be managed by monitoring the head resistance value. The operation assurance temperature of the hard disk differs depending on the design. For example, if the operation assurance temperature is from 0 ° C. to 50 ° C., the head resistance value is 22Ω to 29.5Ω due to the temperature dependence of the head resistance value shown in FIG. It can be inferred that the range up to is within the compensation range. If the head resistance value is out of the range of 22Ω to 29.5Ω, it can be estimated that the ambient temperature is out of the guaranteed range. Also, if you continue to use this device at an environmental temperature outside the guaranteed range,
In the worst case, there is a risk that the apparatus and data are destroyed. Therefore, a warning means for issuing a warning to the user is connected to the interface 8, and when the measured head resistance value is out of the range of 22Ω to 29.5Ω, a warning signal is issued to the warning means through the interface 8 to the user. A warning can be issued, and destruction of the apparatus and data can be prevented.

In the third embodiment, the microcomputer 17 is provided with a control routine for operating the fixed magnetic recording apparatus so as to control the fixed magnetic recording apparatus. However, the microcomputer 17 stores a temperature characteristic of the head resistance value of the MR head. A step of measuring a head resistance value of the MR head when the MR head is in an operation waiting state, and a third step of calculating a temperature based on the measured head resistance value. The control routine is executed by diskware (DISKWAR) for storing the program of the magnetic disk 12.
The same effect is obtained even when recording is performed in E) or the like.

(Embodiment 4) As shown in FIG. 12, a fixed magnetic recording apparatus according to Embodiment 4 of the present invention comprises a plurality of MR heads measured by the microcomputer 17 of Embodiment 3 described above. The microcomputer 18 further includes a function of calculating a temperature based on the resistance value and the temperature characteristic and predicting the degree of the characteristic deterioration of the MR head based on the calculated temperature.

As in the third embodiment, when the MR head is in the operation waiting state, the head resistance value of the MR head is calculated and stored in the buffer 16, and the measurement is performed by measuring the head resistance values of all the MR heads. Stores a value. Further, a measured value obtained by measuring the head resistance value of a plurality of MR heads requiring measurement may be stored. Generally, these multiple MR heads are constantly operating or waiting for operation.

The microcomputer 18 has a buffer 1
6, the respective temperatures are calculated based on the measured head resistance values of the plurality of MR heads. If there is an MR head that shows a prominent temperature with respect to the whole, it is predicted that this MR head has changed over time. With this configuration, the head resistance value or its change is stored in the buffer 16.
, And the secular change can be predicted by constantly monitoring the change with respect to the latest value. In general, the fact that the head resistance value largely changes even though the ambient temperature is constant is presumed that the MR element has changed over time. However, it is difficult to determine whether the resistance change is due to the ambient temperature or due to aging, except for the case where the resistance value rises momentarily due to the thermal asperity (TA) phenomenon, by monitoring only a single head. Therefore, by using a plurality of MR heads, it is possible to estimate whether the change in the head resistance is due to the ambient temperature or permanent. For example, in a fixed magnetic recording apparatus having four MR heads, when the head resistance values of all four MR heads change, it is considered that this is due to a temperature change. When only the head resistance value of one of the four MR heads changes, it is considered that the MR head characteristically changes from the factory shipment. By studying the design, data on how much the head resistance value has a significant effect on the performance is statistically acquired.

For example, when the head resistance value fluctuates by 10% or more due to factors other than temperature, it is considered that the MR element has been damaged in some way. While constantly monitoring the aging of the value, it is constantly compared with the value before shipment whether or not a change of 10% or more has occurred. If the change exceeds 10%, the user's data recorded on the media may be lost or the device may be destroyed.

Therefore, the warning means 19 for warning the user of the degree of characteristic deterioration is connected to the interface 8, and when the change exceeds 10%, a warning signal is issued to the warning means 19 through the interface 8 to warn the user. Can be issued to warn the user of the degree of characteristic deterioration, and destruction of the apparatus and data can be prevented.

(Embodiment 5) In a fixed magnetic recording apparatus according to Embodiment 5 of the present invention, as shown in FIG. Resistance) A monitoring means 21 is provided for monitoring the variation of the flying height of the MR head based on the output variation when the head passes over the bumps 23.

As shown in FIG. 14, bumps 23 are formed of the same material as the magnetic disk 20 on the surface of the magnetic disk 20. The diameter of the bottom surface of the bump 23 is, for example, 2.0 to 3.0 μm, and the height of the bump 23 is, for example, 0.1 to 0.15 μm. This bump 23
A plurality of magnetic disks may be formed on the magnetic disk 20. The desired bumps 23 are formed on the surface of the magnetic disk 20 by using the laser zone texture technique. The basic principle of the MR head is to detect and output a change in the resistance value, but the thermal stability of the sensor part becomes important. In a normal operation, when the MR portion touches an abnormal projection on the surface of the magnetic disk 20, the head resistance increases instantaneously, causing output fluctuation. Generally, this phenomenon is called thermal asperity (TA), and in magnetic disk design, this phenomenon is corrected in a circuit or the smoothness of the magnetic disk is improved to improve the magnetic disk.

In the thermal asperity phenomenon, if the degree of fluctuation of the output is the same for bumps, the lower the flying height, the greater the collision. Here, the operation of the fixed magnetic recording device for measuring the output value of the MR head to prevent a crash beforehand will be described. When receiving an instruction from the microcomputer 22, the preamplifier 3 changes the head resistance value of the MR head every time the MR head of the head structure 1 passes over the bump 23 formed at a predetermined position on the disk 20. It is observed that the output value rises and the output value of the MR head rises.

The monitoring means 21 previously stores, as an initial value, the amount of output fluctuation when the MR head passes over the bump 23 during manufacturing. Upon receiving an instruction from the microcomputer 22, the output fluctuation amount is periodically measured, and the measured value is compared with an initial value to estimate a change in the flying height,
Monitor the risk of crash. Specifically, when the flying height is good, as shown in FIG.
Is about 100 mV, for example, and the monitoring means 21 previously stores the output fluctuation of the MR head 100 mV at the time of manufacture as an initial value. In the monitoring means 21, for example, when the fluctuation amount becomes larger than 20%, there is set a threshold value of 120 mV assuming that there is a danger of a crash and that there is a danger of a crash. If the flying height is reduced by periodically measuring the output fluctuation amount, as shown in FIG. 16, the output fluctuation amount when passing over the bump 23 increases to about 170 mV,
Assuming that the threshold value is exceeded, a warning signal is output to the warning means via the interface 8 to notify the user of the danger of a crash.

With this configuration, by monitoring the output fluctuation amount, it is possible to estimate a change in the flying height of the MR head. If the fluctuation amount becomes a predetermined value or more, there is a risk of the user crashing in advance. Can be warned that
Destruction of the apparatus and data can be prevented. In the fifth embodiment, the microcomputer 22 is provided with a control routine for operating the fixed magnetic recording device so as to control the fixed magnetic recording device. However, the microcomputer 22 measures the amount of output fluctuation when passing over the bumps 23 of the MR head. A control routine including a first step of storing, a second step of determining whether the stored output fluctuation amount exceeds a threshold value, and a third step of issuing a warning when the stored output fluctuation amount exceeds the threshold value. Is recorded in diskware (DISKWARE) or the like for storing the program of the magnetic disk 20.

In the fifth embodiment, M during normal operation
Although the output fluctuation amount of the R head is measured and stored, the same effect is obtained even when the output fluctuation amount of the MR head in the operation waiting state is measured and stored. Further, in each of the embodiments described above, the read-only head is an MR (magnetoresistive) head, but the same effect can be obtained even when a GMR (giant magnetoresistance) head is used.

[0070]

As described above, according to the bias current control method of the magnetoresistive head according to the first aspect of the present invention, each time the magnetoresistive head accesses the magnetic disk, the bias current value of the magnetoresistive head is changed. Executing the measurement to optimize, updating and storing the bias current value of the magnetoresistive head to the measured optimal bias current value, and supplying the stored optimal bias current to the magnetoresistive head. By reading the data recorded on the magnetic disk, the bias current of the magnetoresistive head can be appropriately optimized during the operation of the fixed magnetic recording apparatus according to the operation of the magnetoresistive head, and the characteristics of the magnetoresistive head during the operation can be optimized. Can maintain the optimum bias current even when the time varies with the passage of time, and the reproduction signal waveform from the magnetoresistive head Asymmetric distortion due to saturation can be suppressed, the error rate during data reading can be reduced, and the optimum bias current is supplied to the magnetoresistive head. This can prevent the average life from being shortened.

More specifically, optimization of the bias current of the magnetoresistive head can be appropriately performed during the operation of the fixed magnetic recording apparatus in accordance with the operation of the magnetoresistive head. And a decrease in performance due to a gradual increase in resistance can be prevented. Even in actual use, the optimum value of the bias current can be updated each time the environment changes, and deterioration of the characteristics of the device with time can be prevented. Further, the design can be performed with a margin at room temperature suppressed, and the yield of products can be improved.

According to the bias current control method for a magnetoresistive head according to the second aspect of the present invention, when the magnetoresistive head enters an operation waiting state, measurement for optimizing the bias current value of the magnetoresistive head is executed. Then, the bias current value of the magnetoresistive head is updated and stored to the measured optimum bias current value, and the stored optimal bias current is supplied to the magnetoresistive head and recorded on the magnetic disk. By reading the data, the same effect as the above-described method of controlling the bias current of the magnetoresistive head according to claim 1 of the present invention is obtained.

According to the fixed magnetic recording apparatus of the third aspect of the present invention, each time the magnetoresistive head accesses the magnetic disk, an optimum measurement for optimizing the bias current value of the magnetoresistive head is executed. Controlling the optimization measuring means, updating and storing the bias current value of the magnetoresistive head to the measured optimal bias current value, and storing the updated and stored optimal bias current. By providing the processing means for outputting an instruction to be supplied to the magnetoresistive head, the bias current control method for a magnetoresistive head according to claim 1 of the present invention can be realized.

According to the fixed magnetic recording device of the fourth aspect of the present invention, the optimization measuring means of the fixed magnetic recording device according to the third aspect of the present invention uses the optimization measuring means when the magnetoresistive head enters an operation waiting state. By changing to an optimized measurement unit that performs measurement to optimize the bias current value of the resistance head,
According to a second aspect of the present invention, there is provided a method of controlling a bias current of a magnetoresistive head.

According to the magnetic disk of the present invention, the control routine for operating the central processing unit for controlling the fixed magnetic recording device is changed every time the magnetoresistive head accesses the magnetic disk. A first step of optimizing a bias current value of the magnetoresistive head;
A second step of updating and storing the bias current value of the magnetoresistive head to the measured optimal bias current value, and a third step of supplying the updated and stored optimal bias current to the magnetoresistive head. With the configuration and recording of the steps, the bias current value of the magnetoresistive head can be optimized by executing the control routine recorded on the magnetic disk.

According to the magnetic disk of the present invention, when the magnetoresistive head enters the operation waiting state, the bias current of the magnetoresistive head is changed to the first step. By replacing the first step of optimizing the value, the same effect as that of the magnetic disk according to claim 5 of the present invention can be obtained. Further, according to the fixed magnetic recording apparatus of the present invention, the storage means for storing the temperature characteristics of the head resistance value of the magnetoresistive head, and the magnetoresistive head when the magnetoresistive head enters an operation waiting state. The use of a magnetoresistive head as a temperature sensor without providing a temperature sensor separately by providing a measuring means for measuring the head resistance value of the above and a calculating means for calculating the temperature based on the measured head resistance value Can monitor the temperature.

According to the magnetic disk of the present invention, the control routine for operating the central processing unit for controlling the fixed magnetic recording device is provided by a temperature characteristic of the head resistance value of the magnetoresistive head. , A second step of measuring a head resistance value of the magnetoresistive head when the magnetoresistive head is in an operation waiting state, and calculating a temperature based on the measured head resistance value. By composing and recording in the third step,
By executing the control routine recorded on the magnetic disk, the magnetoresistive head can be used as a temperature sensor.

According to the fixed magnetic recording device of the present invention, the storage means for storing the temperature characteristics of the head resistance values of the plurality of magnetoresistive heads, respectively, and the magnetoresistive head is in an operation waiting state. Measuring means for measuring a head resistance value of the magnetoresistive head, and calculating a temperature based on the measured head resistance values of the plurality of magnetoresistive heads and the temperature characteristic, based on the calculated temperature. And the prediction means for predicting the degree of characteristic deterioration of the magnetoresistive head, it is possible to monitor the secular change of the magnetoresistive head, and to predict the life of the fixed magnetic recording apparatus.

According to the fixed magnetic recording device of the present invention, the fixed magnetic recording device of the ninth aspect warns the predicting means of the degree of characteristic deterioration of the magnetoresistive head. By providing the warning means, a warning can be issued to the user. Further, according to the fixed magnetic recording device of the present invention, a protrusion is provided at a specific position on the magnetic disk, and based on the output fluctuation amount when the magnetoresistive head passes over the protrusion. By providing the monitoring means for monitoring the variation in the flying height of the magnetoresistive head, the variation in the flying height of the magnetoresistive head can be monitored, and a crash can be prevented.

Further, according to the fixed magnetic recording apparatus of the present invention, the fixed magnetic recording apparatus of the above-mentioned claim is provided with a warning means for warning that the output fluctuation exceeds a threshold value. This can warn the user that there is a risk of crash. According to the magnetic disk of the present invention, a control routine for operating the central processing unit for controlling the fixed magnetic recording apparatus is provided with an output when passing over the protrusion of the magnetoresistive head. A first step of measuring and storing a fluctuation amount, a second step of determining whether the stored output fluctuation amount exceeds a threshold value, and a third step of giving a warning when the stored output fluctuation amount exceeds the threshold value. By composing and recording
By executing the control routine recorded on the magnetic disk, it is possible to monitor the fluctuation of the flying height of the magnetoresistive head.

Further, according to the magnetic disk of the present invention, the first step of the magnetic disk according to the above-mentioned claim 13 is performed when the magnetoresistive head is in an operation waiting state. By replacing the first step of measuring and storing the amount of output fluctuation when passing over the protrusion, the same effect as that of the magnetic disk according to claim 13 of the present invention can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a fixed magnetic recording device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a format of a recording surface of the magnetic disk according to the first embodiment;

FIG. 3 is an explanatory diagram showing a measurement pattern area of the magnetic disk according to the first embodiment;

FIG. 4 is an explanatory diagram showing a measurement pattern in a measurement pattern area according to the first embodiment;

FIG. 5 is a reproduction waveform diagram when the measurement pattern area of the first embodiment is reproduced.

FIG. 6 is an explanatory diagram showing a change in a signal-to-noise ratio with respect to a change in a bias current according to the first embodiment;

FIG. 7 is a block diagram illustrating a configuration of a fixed magnetic recording device according to a second embodiment of the present invention;

FIG. 8 is a correspondence diagram showing an optimum bias current value according to the head resistance value of the second embodiment.

FIG. 9 is a block diagram showing a configuration of a fixed magnetic recording device according to a third embodiment of the present invention.

FIG. 10 is a characteristic diagram showing temperature dependence of a head resistance value according to the third embodiment.

FIG. 11 is a temperature correspondence diagram of a head resistance value according to the third embodiment.

FIG. 12 is a block diagram illustrating a configuration of a fixed magnetic recording device according to a fourth embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a fixed magnetic recording device according to a fifth embodiment of the present invention.

FIG. 14 is a schematic external view showing the shape of a bump according to the fifth embodiment.

FIG. 15 is a waveform chart showing an output fluctuation amount due to a TA phenomenon in a good case of the fifth embodiment.

FIG. 16 is a waveform chart showing an output fluctuation amount due to a TA phenomenon in an abnormal case according to the fifth embodiment.

FIG. 17 is a resistance value distribution diagram showing a variation in head resistance value of a conventional MR head.

FIG. 18 is a waveform diagram showing the bias current dependency of the conventional head output.

FIG. 19 is a block diagram showing a configuration of a conventional fixed magnetic recording device.

FIG. 20 is a block diagram showing a configuration of a main part for measuring a head resistance value of a conventional MR head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head structure part 1a, 1b Head structure part 2, 12 Magnetic disk 3 Preamplifier 3a, 3b Preamplifier 4 Data channel 5, 13 GEM 6, 14 Hard disk controller 7, 15 Buffer 8, 16 Microcomputer 9 Interface 10, DESCRIPTION OF SYMBOLS 11 Optimization measuring means 17, 18 Microcomputer 19 Warning means 20 Magnetic disk 21 Monitoring means 22 Microcomputer 23 Bump

Claims (14)

[Claims] When controlling a bias current supplied to a magnetoresistive head for reading data recorded on a magnetic disk, the bias current value of the magnetoresistive head is optimized each time the magnetoresistive head accesses the magnetic disk. Executing the measurement to update the bias current value of the magnetoresistive head to the measured optimal bias current value and storing the updated bias current value, supplying the stored optimal bias current to the magnetoresistive head, and A bias current control method for a magnetoresistive head that reads data. 2. A method for controlling a bias current to be supplied to a magnetoresistive head for reading data recorded on a magnetic disk, wherein the bias current value of the magnetoresistive head is optimized when the magnetoresistive head is in an operation waiting state. The bias current value of the magnetoresistive head is updated to the measured optimal bias current value and stored, and the data is read by supplying the stored optimal bias current to the magnetoresistive head. A bias current control method for a magnetoresistive head. 3. A fixed magnetic recording apparatus for recording data on a magnetic disk and reading the data with a magnetoresistive head, wherein a bias current value of the magnetoresistive head is optimized each time the magnetoresistive head accesses the magnetic disk. An optimization measuring means for executing the measurement to be performed, controlling the optimization measuring means, updating and storing the bias current value of the magnetoresistive head to the measured optimal bias current value, and storing and updating the updated bias current value. A fixed magnetic recording apparatus provided with processing means for outputting an instruction to supply an optimum bias current to the magnetoresistive head. 4. A fixed magnetic recording apparatus for recording data on a magnetic disk and reading the data with a magnetoresistive head, wherein when the magnetoresistive head is in an operation waiting state, measurement for optimizing a bias current value of the magnetoresistive head is performed. Optimizing measuring means to be executed, controlling the optimizing measuring means, updating and storing the bias current value of the magnetoresistive head to the measured optimum bias current value, and updating and storing the optimum stored bias. Processing means for outputting an instruction to supply current to the magnetoresistive head. 5. A magnetic disk on which a control routine for operating a central processing unit for controlling a fixed magnetic recording device is recorded, wherein the control routine is executed each time a magnetoresistive head accesses the magnetic disk. A first step of optimizing a bias current value of the resistance head; a second step of updating and storing the bias current value of the magnetoresistive head to the measured optimum bias current value; And a third step of supplying the updated and stored optimum bias current to the head, and recording the control routine. 6. The magnetic disk according to claim 5, wherein the first step is configured to optimize a bias current value of the magnetoresistive head when the magnetoresistive head enters an operation waiting state. 7. A fixed magnetic recording device for recording data on a magnetic disk and reading the data with a magnetoresistive head, a storage means for storing a temperature characteristic of a head resistance value of the magnetoresistive head, wherein the magnetoresistive head operates. A fixed magnetic recording apparatus comprising: a measuring unit for measuring a head resistance value of the magnetoresistive head in a waiting state; and a calculating unit for calculating a temperature based on the measured head resistance value. 8. A magnetic disk recording a control routine for operating a central processing unit for controlling a fixed magnetic recording device, the control routine storing a temperature characteristic of a head resistance value of a magnetoresistive head. A first step, a second step of measuring a head resistance value of the magnetoresistive head when the magnetoresistive head is in an operation waiting state, and a third step of calculating a temperature based on the measured head resistance value And a magnetic disk in which the control routine is recorded. 9. A fixed magnetic recording apparatus having a plurality of magnetoresistive heads for reading data recorded on a magnetic disk, a storage means for storing temperature characteristics of head resistance values of the plurality of magnetoresistive heads, respectively, Measuring means for measuring a head resistance value of the magnetoresistive head when the head is in an operation waiting state; and calculating a temperature based on the measured head resistance values of the plurality of magnetoresistive heads and the temperature characteristic, A fixed magnetic recording apparatus provided with prediction means for predicting the degree of characteristic deterioration of the magnetoresistive head based on the calculated temperature. 10. The fixed magnetic recording apparatus according to claim 9, further comprising warning means for warning the degree of characteristic deterioration of the magnetoresistive head from the prediction means. 11. A fixed magnetic recording device for recording data on a magnetic disk and reading the data with a magnetoresistive head, wherein a protrusion is provided at a specific position on the magnetic disk, and the magnetoresistive head passes over the protrusion. A fixed magnetic recording apparatus provided with monitoring means for monitoring a change in a flying height of the magnetoresistive head based on an output change amount when the magnetic head is driven. 12. The fixed magnetic recording apparatus according to claim 11, further comprising warning means for warning that the amount of output fluctuation exceeds a threshold value. 13. A magnetic disk on which a control routine for operating a central processing unit for controlling a fixed magnetic recording apparatus is recorded, wherein the control routine is executed when the magnetic disk passes over a protrusion of the magnetoresistive head. A first step of measuring and storing the amount of output fluctuation; a second step of determining whether the stored amount of output fluctuation exceeds a threshold; and a third step of issuing a warning if the amount of output fluctuation exceeds the threshold. And a magnetic disk on which this control routine is recorded. 14. The magnetic recording apparatus according to claim 13, wherein the first step is configured to measure and store an output fluctuation amount when the magnetoresistive head passes over a protrusion of the magnetoresistive head when the magnetoresistive head is in an operation waiting state. disk.