JP2000090404A - Magnetic disk device and magnetic head assembly body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable controlling a device in accordance with a discriminated result by classifying magnetic heads as heads of which characteristics are different without eliminating dispersion of characteristics of magnetic heads as much as possible, incorporating then in a device, and discriminating a type of an incorporated head. SOLUTION: Besides a terminal 10 for signal of a MR head and a terminal 10 for signal of a recording head, a terminal 11 for discriminating an element is provided at a connection part of a a connector of a head arm 3. an impedance 17 is connected between two terminals for discriminating an element, or the terminal 11 is grounded or made an open state. A head type discriminating part 16 supplies a current to the terminal 11, measures voltage between terminals, or discriminates a type of a head mounted on a head arm by detecting a ground or open state of the terminal 11, and outputs a discriminated result to a controller 8. The controller 8 sets and controls parameters of a R/W amplifier and a R/W channel based on the discriminated result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive, and more particularly to a device for identifying the type and characteristics of a head and automatically setting the operation of the device.

[0002]

2. Description of the Related Art In a magnetic disk drive, information (signal) is recorded on a magnetic disk medium using a magnetic head and is reproduced. The magnetic head replaces the inductive magnetic head,
Recently, (giant) magnetoresistive effect MRE (Magnetor
GMR (Giant-Magneto-Resistiv) using esistive-Effect; the effect of changing electrical resistance under the influence of an external magnetic field
e) The head is mainly used. That is, the MR head is a read-only head, and an inductive head is used for recording information. The GMR head uses a multilayer film exhibiting a giant magnetoresistance effect, whereas the MR head uses a single layer film (eg, a Ni—Fe film) exhibiting an anisotropic magnetoresistance effect. The GMR head is also a head used only for signal reproduction. An inductive head is used for writing information.

The principle of reproduction is the same as that of an MR head.
Magnetically recorded information is reproduced using an element whose electric resistance changes according to a change in a magnetic field. The sensitivity of the element used at this time (the rate of change in resistance with respect to the change in the magnetic field) is several times higher than the element used in the MR head. In such a GMR head, a recording head element is integrally formed by a thin film process to constitute a composite recording / reproducing head.

When the recording magnetic field of the head or the reversal magnetic field of the recording medium varies, normal recording may not be performed. For this reason, it is important to set the magnetization of the recording medium to be as saturated as possible with respect to the recording current applied to the magnetic head (saturated recording). In determining the recording current of the head, in addition to the above-mentioned saturation characteristics, it is necessary to consider a wide variety of issues such as the recording width and erasing width, and the recording demagnetization. Further, with respect to the MR head for reproduction, it is necessary to determine an operating point at which a proper design output and a proper waveform amplitude symmetry are obtained, and set a sense current. The controller (MPU) controls the R / W AMP for the recording and sense currents applied to the magnetic head.

[0005] Information to be recorded by the magnetic head is transmitted through an interface connecting the host device to the magnetic disk device.
As a recording signal from the R / W channel, R / W AMP
Given to. The R / W AMP supplies a reversing recording current corresponding to a recording signal to a magnetic head. During reproduction, a sense current is sent to the MR head to receive a reproduction output. The reproduction output is amplified and sent to the R / W channel, where it is reproduced as information. In the R / W channel, conversion between information and recording / reproducing signals is performed.

In recent years, in particular, PRML (Pa
(rtial-Response-Maximum-Likelihood) system is adopted, and the discrimination performance from a low S / N reproduction signal is improved. The PRML method is one of methods for detecting information from a reproduced waveform, and a partial response method that can reproduce information even when waveform interference occurs between waveforms corresponding to information and a method in which noise is included in a waveform. And a combination of the Viterbi compound method for reproducing the most likely information sequence. This method requires more complicated processing than the peak detection method, but is suitable for high-density recording. In the PRML system, in order to effectively use the front-rear interference of the reproduced signal waveform, it is necessary to equalize the reproduced signal waveform to the target waveform to optimize the waveform interference. If the equalization error is large, a discrimination error is likely to occur, and a reproduction error of recorded information may occur.
Waveform equalization techniques are particularly important. For this reason, in many cases, the adaptive equalization technique is combined, and even when there is a variation in the reproduction waveform due to the variation in the characteristics of the head, the disk, and the like, the reproduction waveform is equalized to the target waveform. In general adaptive equalization, the amount of equalization error at each point where the reproduced waveform is sampled is evaluated, and the equalization coefficient of each tap of the transversal equalizer is learned and applied so that the equalization error is reduced as much as possible. .

In addition, various automatic adjustment functions have been applied to absorb deviations in synchronization timing and the like at the time of reading caused by variations in elements inside the recording / reproducing channel IC. These technologies are rapidly expanding their applications due to recent advances in digital technology. This PR
The controller automatically adjusts the ML parameters for the R / W channel. In addition, there is a demand for an apparatus having means for stabilizing the function of the apparatus by performing setting according to variations as much as possible with respect to other parameters for which no adjustment work is performed.

[0008]

In the prior art, variations in the processing and characteristics of the recording / reproducing elements appear as variations in the performance of the apparatus. Therefore, elements that do not meet the initially set sorting criteria are excluded. For example, when the gap depth of the recording head varies depending on the head, the recording current-recording magnetic field characteristics (hereinafter, saturation characteristics) greatly change. For a given recording current, if the magnetization of the recording medium is not sufficiently saturated, the necessary recording magnetic field changes according to the change in the switching magnetic field of the recording medium during high-temperature operation and low-temperature operation. Data recording may not be performed normally. As a result, it is easy for the reliability and stability of the device to vary greatly. Therefore, it is important to set the recording current so that sufficient saturation recording is performed. However, as described above, since the recording current affects the recording width, the erasing width, the recording demagnetization, and the like in addition to the saturation characteristics, the optimum recording current differs depending on the head. For this reason, the recording current is fixed to a certain uniform value such as the value in the head design, and the one that does not provide the required characteristics by this value is eliminated. It needs to be taken into account.

For a reproducing MR head, a sense current is set so as to obtain a proper output in design and a symmetry of a proper waveform amplitude. However, the asymmetry of the positive and negative waveform amplitudes increases due to variations in operating points and the like, and deviations and variations from design values appear. Those with a large asymmetry
In the above-described signal processing performed on the R / W channel, a waveform equalization error occurs, and a problem is easily caused. Therefore, it is necessary to set a certain reference, to exclude those with large asymmetry, and to take into account the waveform equalization error due to the variation and the performance degradation accompanying the non-exclusion.

An object of the present invention is to provide means for classifying heads having different characteristics and incorporating them into an apparatus without eliminating these characteristic variations as much as possible. To this end, a means is provided for identifying differences in the characteristics of the classified heads. In addition, the present invention provides means for automatically performing various settings in the apparatus in accordance with the classification, thereby reducing variations in the performance of the apparatus. This also provides a means for improving the stability and reliability of the function of the device.

[0011]

According to the present invention, in order to achieve the above object, the present invention relates to a magnetic disk drive having a magnetic head assembly, an R / W amplifier, a control unit, and an R / W channel. Two or more element identification terminals were provided in addition to a terminal for transmitting a recording / reproducing signal to a connection portion of the magnetic head assembly, and mounted on the magnetic head assembly based on the impedance between the element identification terminals. A head type identification unit for generating an identification signal for identifying a head type is provided, and the control unit sets and sets parameters of the R / W amplifier and / or R / W channel based on the identification signal from the head type identification unit. I try to control.

Also, in a magnetic disk drive having a magnetic head assembly, an R / W amplifier, a control section, and an R / W channel, a terminal for transmitting a recording / reproducing signal to a connection section of the magnetic head assembly. A head type identification unit for generating an identification signal for identifying a head type mounted on the magnetic head assembly based on an open state of the element identification terminal; The control unit sets and controls the R / W amplifier and / or R / W channel parameters based on the identification signal from the head type identification unit.

The control section sets the symmetry correction parameter of the R / W channel based on the identification signal from the head type identification section. Further, the control section switches the recording current by the head by controlling the R / W amplifier based on the identification signal from the head type identification section. When the read head mounted on the magnetic head assembly is a head utilizing the magnetoresistance effect, the read / write amplifier and the impedance between the element identification terminals are switched and measured in the R / W amplifier. Accordingly, the R / W amplifier also serves as the head type identification unit.

Also, in a magnetic head assembly having a magnetic information recording / reproducing element and a connecting portion having a terminal for electrically connecting a terminal of the recording / reproducing element to an external circuit, the connecting portion includes In addition, a terminal for identifying the head type based on the impedance between terminals and the open state of the terminal is provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a configuration of the magnetic disk drive. A magnetic disk 1 having a magnetic layer formed on its surface is fixed to an axis of a motor 2 and rotates, while a recording / reproducing element (not shown) incorporated at the tip of a head arm 3 transfers information to the magnetic layer. Recording and playback are performed. A head arm 3, which is a magnetic head assembly, includes a support plate 4 and a load spring 5 fixed to the support plate 4.
And a slider 6 attached to the tip of the load spring 5. The read / write element is incorporated in the head slider 6, and records information on a magnetic layer formed on the surface of the magnetic disk while maintaining an appropriate distance from the magnetic disk 1 with an appropriate load by the load spring 5. Or data reproduction. The head arm 3 is attached to the voice coil motor 7 and drives the voice coil motor 7 based on an instruction from the controller 8 to position the head arm 3 at a specific position on the magnetic disk. Recording and playback.

When data is recorded or reproduced, a recording current and a sense current required for the R / W AMP 14
Given by The controller 8 sends an instruction signal via the control signal line 25, and the R / W AMP 14 supplies a recording current and a sense current to the recording / reproducing element according to the instruction. A signal line 9 from a recording / reproducing element incorporated in the head slider 6 is supplied from a connector 12 connected to a terminal 10 provided on the head arm 3 to a R / W AM.
Connected to P14. Via these, it is connected to a recording / reproducing channel 13 (hereinafter referred to as R / W channel). Will be

FIG. 3 is a diagram showing the upper surface of a head arm 3 which is an example of the magnetic head assembly according to the present invention. The head arm 3 has a load spring 5 fixed to a support plate 4, and a slider 6 having a recording / reproducing element incorporated therein is attached to the tip of the load spring. In order to connect the signal extracted from the signal terminal of the recording / reproducing element to the R / W AMP 14,
A connection portion having a terminal 10 was provided on the head arm, and this terminal was inserted into the connector 12 connected to the input / output terminal of the R / W AMP 14 in the device. In addition to the recording / reproducing signal terminal, a connection portion having a terminal (hereinafter referred to as an element identification terminal) 11 for distinguishing the type of head is provided. In this example, one connection part is formed by the connection part having the terminal 10 and the connection part having the terminal 11, but each connection part may be arranged at a different position. Similarly, to connect to the R / W AMP 14, the connector 1
Inserted in 2. The terminals 10 and 11 are configured by providing a portion for terminals on the head arm support plate 4 and bonding a printed circuit board 20 (hereinafter, referred to as FPC) having a terminal pattern formed on one end. At the other end of the FPC 20, a relay terminal pattern 21 for connecting a signal lead-out wiring 22 from the recording / reproducing head element was formed, and the signal lead-out wiring 22 from the recording / reproducing head element was connected by thermocompression bonding.

FIG. 1 is a block diagram showing an outline of the configuration of a magnetic disk drive according to the present invention.

The present invention relates to an element identification terminal 11 of the connector section and a head identification section 1 for detecting the state of the terminal.
6. It has a controller 8 for reflecting the result to settings such as adjustment and learning. As described in the configuration, the recording / reproducing signal is supplied from the connector recording / reproducing signal terminal 10 to the R / W.
It is connected to the AMP 14 and sent to the R / W channel 13 as an output of the R / W AMP 14. Separately, a signal for element identification is sent from the element identification terminal 11 provided in the connector section to the controller 8 via the element identification section 16 for detecting the state of this terminal. The controller 8
The type of the head is identified from the output of the element identification unit 16,
A preset value is given to the R / W AMP 14 and the R / W channel 13. In FIG. 1, the element identification section 16 and the R / W AMP 14 are described as separate elements, but this clarifies that the purpose of use is conceptually different. Is R / W
It is desirable to implement it in a form to be included in the AMP 14, the controller 8, and the like.

As a first embodiment, automatic setting of the recording current will be described. FIG. 4 is a diagram showing the saturation characteristics of the two types of magnetic heads used in the first embodiment. The recording current is displayed on the horizontal axis. The vertical axis shows the magnitude of the residual component (hereinafter, O / W characteristic) when the higher frequency signal is overwritten on the low frequency signal. (1) in the figure 24mA ₀ -p, (2) is about 30 mA ₀
The saturation point has been reached with -p. Recording current (1) from consideration of the recording width and resolution, etc. and the properties mentioned above this characteristic diagram, 24mA ₀ -p~30mA ₀ -p was appropriate value. (2) is
32mA was _{0 -p~36mA 0} -p. Here, as an example of classification, when the recording current is set to 24 mA ₀ -p, the O / W characteristic becomes -35d
Judge the thing smaller than B to have the characteristic close to (1),
Classified as "Group A". Also in 24mA ₀ -p recording current does not satisfy the same conditions, the recording current when the 34 mA ₀ -p, was that meets this condition is classified as "Group B". In addition to this, there is no problem in performing any classification such as classification based on output, in addition to O / W characteristics.

The recording current of the head of the group A was set to 26 mA ₀ -p, and a resistor of 20 Ω was attached as a discriminating resistor between the element discriminating terminals 11 formed by FPC. Recording current is 34mA for group B
_0- p shall be set, and 30
A Ω resistor was attached. In order to measure the voltage between the element identification terminals 11, the output of the element identification terminal 11 was connected to the element identification section 16 as shown in FIG. 5 mA ₀ -p was passed through the element identification terminal 11 as an identification current. However, as a conventional technique, there is a R / W AMP having a voltage between MR head terminals and an output function, and it is possible to share the R / W AMP.

FIG. 6 shows an example of this sharing. That is, in the R / W AMP, the measurement of the voltage between the INP1 terminals and the measurement of the voltage between the INP2 terminals are performed by R / W AM
R / W AM
P is also used as an element identification unit. Controller (M
PU) 8 is an output value (BHV Buf) of the R / W AMP 14
The resistance between the element identification terminals 11 is calculated from the fered head voltage. Based on this result, the controller 8
Instructs the R / W AMP 14 via the control signal line 25 the recording current values of the groups A and B defined above. The R / W AMP 14 determines, based on the instruction signal,
A recording current is applied to the head. Thus, the recording current was set according to the difference in the characteristics of the recording head.

As a second embodiment, the R / W channel 13
Automatic setting of parameters for correcting the asymmetry of the positive and negative polarities of the waveform amplitude will be described. For the sake of simplicity, here, they are classified as follows by asymmetric size. A group having an asymmetry of 5% or less was designated as Group C, a group having an asymmetry larger by 5 to 10% as Group D, and a group having asymmetry being 5 to 10% larger in the negative direction as Group E. The identification resistances of the heads of the groups C, D, and E were set to 40Ω, 50Ω, and 60Ω. As in the first embodiment, a voltage is measured by flowing a current for identification of 5 mA ₀ -p,
The group of the head was identified from the calculated resistance value. Based on this result, the controller 8 sets the R / W channel 13
, An instruction signal is sent to set a correction parameter. The R / W channel 13 sets an asymmetry correction parameter according to the instruction signal. In this manner, according to the difference between the positive and negative asymmetries of the waveform amplitude, R
/ W channel 13 parameters were set. Here, the element identifying terminal 11 and the element identifying section 16 for identifying the state between the terminals will be further described. In the above two embodiments, a resistance element is used for the identification terminal 11, but it is not particularly limited to a resistance, and any impedance may be used as long as it can be easily measured. However, the identification terminal 11
The impedance between the two is desirably small in physical volume because wiring is performed on the FPC 20. This method
Since only the impedance between the terminals of the connector section is changed, the assembling operation itself is the same for any type of head, and there is an advantage that the number of assembling steps can be simplified. Further, since only the impedance between the two terminals is changed, the state between the terminals is infinite. Accordingly, there is an advantage that only two identification terminals 11 need to be added, and the shape of the head arm 3 needs to be changed at a minimum.

The method for identifying and detecting the state between the element identification terminals 11 is based on the above-described method of detecting the impedance and by a logic circuit for determining whether the element identification terminal 11 is grounded or open. It is also possible. First, the element identification terminal 11 of the connector at this time will be described. The element identification terminals 11 are grounded (or connected to a constant potential), as shown in FIG.
Or leave it open. This was wired on the FPC 20 (not shown). The detection circuit of the element identification unit 16 inverts the output signals of these terminals via the inverter 18 and inputs the inverted signals to the controller (MPU) 8. The type of head is identified by logically detecting the open state of the identification terminal 11. For example, when two identification terminals are added as shown in FIG. 7, four groups can be identified as shown in the truth table in FIG. In the truth table, L indicates open and H indicates ground. By increasing the number of terminals, 2 n types can be identified. An advantage of this embodiment is that since the open state of the identification terminal is logically detected, the possibility of erroneous detection is small.

When the identification terminals 11 are actually provided on the head arm 3 and the FPC 20 thereof, an FPC having a dedicated pattern corresponding to the type of the head is prepared from the beginning, and a method of simply adhering them is used. A method of preparing an FPC first, matching it with the head, and processing it during the assembling process can be considered. The former has the advantage that the number of assembly steps does not need to be increased, and the latter has the advantage that components can be shared. Either method has no problem in practicing the present invention.

As an embodiment, an example in which the signal lead-out wiring of the magnetic head element is connected by the relay terminal 21 has been described.
Even if the signal terminal of the magnetic head element is directly joined to the terminal portion of the FPC by extending C20, there is no problem in practicing the present invention. A terminal 10 connected to the recording / reproducing channel 13
However, even if the terminal is formed by another method without using the FPC 20, it is obvious that the present invention can be easily implemented by forming the terminal for identification by the method. Further, the timing of identifying the state of the element identification terminal may be such that all heads are identified at the time of head switching or when the apparatus is started, and are recorded in the memory. Further, the identification may be performed in one step of the manufacturing, adjustment, and inspection stages of the apparatus, and the result may be recorded on a medium (disk), reproduced at a later start-up, and set later based on the information. .

[0027]

According to the present invention, the storage / reproducing elements are classified according to the characteristics and processing variations, and the operation of the device can be set according to the difference in the characteristics, so that the performance and characteristics of the device can be suppressed from variation. . As a result, the stability and reliability of the function are ensured, so that a higher quality magnetic storage device can be supplied.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a configuration of a magnetic disk drive of the present invention.

FIG. 2 is a diagram showing a configuration of a magnetic disk drive.

FIG. 3 is a diagram showing an upper surface of a head arm according to the present invention.

FIG. 4 is a diagram showing saturation characteristics of two types of magnetic heads used in the first embodiment.

FIG. 5 is a diagram showing an element identification unit based on impedance (resistance) detection according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of an element identification unit and an R / W AMP of FIG. 6 according to an embodiment of the present invention;
FIG. 4 is a diagram showing sharing of a voltage output function between MR head terminals. ,

FIG. 7 is a diagram illustrating an element identification unit based on open terminal detection according to an embodiment of the present invention.

[Description of Signs] 1 Magnetic disk 2 Spindle motor 3 Head arm 4 Head arm support plate 5 Load spring 6 Head slider 7 Voice coil motor 8 Controller 9 Recording / reproducing signal line of recording / reproducing element incorporated in head slider 10 Head arm 11 A terminal for element identification provided on the head arm 12 A connector for transmitting signals of the terminals 10 and 11 to the R / W AMP 13 Recording having an automatic adjustment function of signal processing parameters Reproduction channel 14 R / W AMP 16 capable of setting recording current and reproduction current by control signal from controller 16 Element identification unit 17 Impedance between identification terminals 18 Inverter 20 FPC 25 on head arm support plate 25 R / W AMP from controller Communicate instructions Control signal line 30 interface

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasuhiro Kato 2880 Kozu, Odawara-shi, Kanagawa F-term in Storage Systems Division, Hitachi, Ltd. F-term (reference) 5D031 AA04 EE10 5D091 AA08 BB06 FF20 HH20

Claims (6)

[Claims] A magnetic head assembly, an R / W amplifier,
In a magnetic disk device having a control unit and an R / W channel, two or more element identification terminals are provided in addition to a terminal for transmitting a recording / reproduction signal to a connection part of the magnetic head assembly. A head type identification unit that generates an identification signal for identifying a head type mounted on the magnetic head assembly based on impedance between terminals; and the control unit controls the R based on the identification signal from the head type identification unit. A magnetic disk drive characterized by setting and controlling parameters of a / W amplifier and / or R / W channel. 2. A magnetic head assembly, an R / W amplifier,
In a magnetic disk drive having a control unit and an R / W channel, one or more element identification terminals are provided in addition to a terminal for transmitting a recording / reproducing signal to a connection part of the magnetic head assembly. A head type identification unit for generating an identification signal for identifying a head type mounted on the magnetic head assembly based on an open state of a terminal; and the control unit, based on the identification signal from the head type identification unit, A magnetic disk drive characterized by setting and controlling parameters of a / W amplifier and / or R / W channel. 3. The magnetic disk drive according to claim 1, wherein the control unit sets the symmetry correction parameter of the R / W channel based on an identification signal from the head type identification unit. Characteristic magnetic disk drive. 4. The magnetic disk drive according to claim 1, wherein the control unit controls the R / W amplifier based on an identification signal from the head type identification unit to reduce a recording current by the head. A magnetic disk drive characterized by switching. 5. The magnetic disk drive according to claim 1, wherein when the read head mounted on the magnetic head assembly is a head utilizing a magnetoresistance effect, the read head impedance and the element in the R / W amplifier. A magnetic disk drive wherein the R / W amplifier also serves as the head type identification unit by switching and measuring the impedance between the identification terminals. 6. A magnetic head assembly comprising: a magnetic information recording / reproducing element and a connecting portion having a terminal for electrically connecting a terminal of the recording / reproducing element to an external circuit; A magnetic head assembly further comprising a terminal for identifying a head type based on an impedance between terminals and an open state of the terminal.