JPH07334801A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent MR elements from being degraded and to prolong the service life by controlling the energizing time and energizing current to the MR elements. CONSTITUTION:In the magnetic disk device controlling sensing current of MR elements 17, 19 mounted on data heads in accordance with operating states of the heads, the sensing current for the MR element is interrupted or made smaller than the optimum value by a constant current circuit 25 and a sensing current switch 23 during a seeking and is controlled to the optimum value during the following. Moreover, in the data surface sector servo system, a following control in which a servo signal is obtained by making a current successively flow to another MR element of MR elements 17, 19 of data heads at every constant time during the following is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the sense current of an MR element of a magnetic disk device using an MR head to prevent deterioration of the MR element and prolong its life.

[0002]

2. Description of the Related Art Conventionally, a sense current has been passed through an MR element of a data head equipped with an inductive element and an MR element since the magnetic disk was powered on.

Further, the servo signal from the servo surface is detected by the inductive element of the servo head, and the data head mounted with the inductive element and the MR element is positioned on the data track of the data surface.

[0004]

The sense current of the MR element is controlled to prevent deterioration of the MR element and to prolong the life of the MR element.
MR element size for reading information on magnetic disk is 4 × 3 ×
It was as small as 0.02 μm ³ or less, and the sense current value flowing in the MR element was as large as 1 × 10 ⁷ A / cm ² or more, and there was a problem of deterioration due to heat generation.

[0005]

According to the present invention, in order to extend the life of an MR element for reading data mounted on a data head, the magnitude of the sense current of the MR element is increased according to the usage state of the data head. And the energization time.

[0006]

When the sense current of the MR element is large, the deterioration is accelerated. Therefore, when the MR element is not used, it is effective to reduce the sense current value to 1 × 10 ⁶ A / cm ² or less or to cut off the energization.

[0007]

EXAMPLE An example of the present invention will be described with reference to FIG. FIG. 1 shows the configuration of a magnetic disk device of the present invention which uses an inductive element for writing data and an MR element for reading data. Further, a data write operation is referred to as a write, and a data read operation is referred to as a read. The magnetic disks 1, 2, 3 and 4 for recording data are attached to a rotary shaft 5 and rotated at a constant rotation by a spindle motor 6. A servo signal for positioning the head on the recording track in the radial direction is recorded on one side of the disk 3.
Further, data heads 7, 8, 9, 10, 12, 13 for reading and writing data and a servo head 11 for reading and writing servo signals are arranged on the disk. The data head and the servo head are moved in the radial direction of the disk by the rotary actuator 14 and positioned on each recording track. The rotary actuator 14 is driven by a voice coil motor 15. The data head includes the inductive elements 16 and 1
8 and MR elements 17 and 19 are dual heads. The servo head is composed of the inductive element 20. The read / write operation of the data head will be described using the inductive element 16 and the MR element 17. The MR element 17 includes a constant current circuit 25 and a sense current switch 23.
Causes a constant sense current to flow. The output signal of the MR element 17 changes its resistance value due to the magnetic field from the disk, and appears as a voltage change.

The output signal 21 of the MR element is the capacitor 2
The DC component is removed at 8 and 29, and only the change in the magnetic field of the disk is input to the read amplifier 32. The signal amplified by the read amplifier 32 is selected by the select switch 40,
Read / write signal 42 and external interface circuit 4
3 to the external bus 44. Further, the write signal is input to the external interface 43 from the external bus 44 and becomes the read / write signal 42. The read / write signal 42 is input to the write amplifier 37 by the select switch 40 of the data read / write select 41.
The write amplifier 37 energizes the inductive element 16 to generate a magnetic field from the winding of the inductive element 16 to record data on the disk. These operation circuits are referred to as data read / write circuits 59 and 65.

The data read / write select circuit 4
The operation of the select switch 40 of No. 1 is the head select signal 63 and the read / write select signal 64 of the control circuit 90.
Determined by These signals are input to the external interface 43 from the external bus 44 and become the control signal 62, which is input to the control circuit 90.

Next, the servo head will be described. The servo head uses the inductive element 20 to write and read data. The select switch 7 of the servo read / write select circuit 77 is controlled by the servo read / write signal 80 and the read / write select signal 82 of the control circuit 90.
8 is selected, a current is passed through the inductive element 20 by the write amplifier 73 at the time of writing, and the servo signal is recorded on the disk. At the time of reading, the read amplifier 72 amplifies the output signal of the inductive element 20 and outputs it to the control circuit 90.

Next, the operation of positioning the data head on the target track during read / write will be described. FIG. 1 shows a servo surface servo system in which a servo head positions a data head. A position signal for each track recorded on a disk is detected by an inductive element 20 of the servo head 11 and is input to a control circuit 90. . Control circuit 90
Is a voice coil motor drive circuit 95 for moving the head at high speed up to the vicinity of the target track (1/4 track).
Causes a current to flow through the voice coil motor 15. This is called a seek operation. When the position near the target track (1/4 track) is reached, the operation of positioning the head at the center of the target track is started, and the servo head is positioned at the center of the target track. This is called a hollowing operation. The spindle motor 6 is controlled to a constant rotation by the spindle motor control circuit 96.

Next, the control of the sense current of the MR element of FIG. 1 according to the present invention will be described with reference to FIG. 100 indicates the speed when the head moves. Reference numerals 101 and 106 indicate the points of time when the sense current is applied. 102 and 107 are seek operations 103,
The time point of switching from 105 to the following operations 104 and 108 is shown. Reference numeral 110 is a signal for controlling energization of the sense current, and 111 is an energization area. Reference numeral 115 is a signal indicating a read / write time point, and 116 is a data read / write execution area. Thus, during seek operation, M
The sense current to the R element is set to zero, and the sense current is supplied during the hollowing operation. As a result, the time during which the sense current is applied to the MR element can be reduced, so that deterioration of the MR element can be prevented and the life of the MR element can be extended. The time point at which the sense current flows is the time point 102 during the hollowing operation, or
It may be the data read / write area 116. Further, FIG. 9 shows a magnetic disk device using a recording surface 227 having a data recording area and a servo signal recording area on the magnetic recording surface and a servo surface 228 on which a servo signal is recorded. 224 is an adder, 225 is a controller for controlling a voice coil motor, 226 is a rotary actuator, 229 is an MR element of a data head, 230 is an inductive element of a servo head, 221 is a low pass filter, and 223 is a high pass filter. . The seek control of FIG. 9 is similar to that of FIG. 1, and the hollowing control uses a servo signal obtained by adding the high frequency component of the servo signal detected by the servo head and the low frequency component of the servo signal detected by the data head. In this case, it is advisable to set the time point at which the sense current of the MR element is made to flow to a time point 101, which is shortly before entering the hollowing operation 102. This is in consideration of the stability of the MR element up to the operation.

Another embodiment will be described with reference to FIG. Thirteen
Reference numeral 5 is a signal for controlling the sense current value to the MR element.
36 indicates a current value area smaller than the optimum value. Reference numeral 137 indicates an optimum value area. As described above, during a period when the signal from the MR element is unnecessary, the current value to the MR element is reduced, so that the deterioration of the MR element can be prevented and the life of the MR element can be extended. The optimum value area of the sense current value may be the data read / write area 116. The present invention can also be used for hollowing control by a servo signal obtained by adding a high frequency component of a servo signal detected by the servo head during hollowing and a low frequency component of the servo signal detected by the data head. In this case, the optimum value area of the sense current value of the MR element is set in consideration of the stability of the MR element operation,
Slightly before the time of entering the hollowing (1/4 track) to the end of the data read / write 116.

Another embodiment will be described with reference to FIG. Figure 4
Shows a case of a data surface sector servo system in which a track positioning operation is performed by using a disk having a data recording area and a servo signal recording area on a magnetic recording surface and a data head. Reference numeral 135 denotes energization control of the sense current of the MR element of the data head. Reference numeral 137 indicates a sense current conducting area. Reference numeral 116 denotes a data read / write area. 1
Numerals 50 and 155 indicate control of energization of the sense current to the MR element of another data head after the end of read / write. 151,
Reference numeral 156 indicates an energization area for the sense current. This is to position a data head on a target track using one data head of a plurality of data heads, read / write data 116, and then send a servo signal for hollowing control to another data head. In order to obtain more, the sense current is sequentially passed through the MR elements of different data heads at regular intervals for a constant time, and the servo signal input is sequentially switched to control. By doing so, the time for which the sense current is applied to the MR element of one data head can be shortened, so that there is an effect that deterioration of the MR element can be prevented and a longer life can be achieved.

Further, in FIG. 4, as in FIG. 3, the value of the sense current to the MR element may be made smaller than the optimum value during the seek of the data head, and the optimum sense current may be set during the following control. . Further, when sequentially switching to another data head during the hollowing control, the sense current value of the MR element of the other data head may be set to the optimum value during the hollowing and smaller than the optimum value in other cases. By doing this, when reading and writing data,
By setting the sense current of the MR element to the optimum value, it becomes possible to accurately read / write data at the center of the track, and at other times, the current value to the MR element is made smaller and the positioning accuracy at the center of the track is loosened. To do. This allows
The deterioration of the life of the MR element can be prevented, which is effective in extending the life.

FIG. 5 shows the inductive element 240, the MR element 242 and the element center position 24 used for the data head.
The relationship of 1 is shown.

FIG. 6 shows a slider of the data head.
The inductive element 240 and the MR element 242 shown in FIG. 5 are formed on the end surface 260 of the rail at the center of the slider. 26
Reference numeral 1 denotes signal lead terminals of the inductive element and the MR element. Reference numeral 262 denotes a machined surface for generating negative pressure and positive pressure.

FIG. 7 shows a control circuit for the sense current of the MR element. Reference numeral 160 denotes a sense current value signal and 162 denotes a D / A converter. A constant current is supplied to the MR element 182 by the voltage set by the D / A converter 162. In addition, the sense current ON signal 180 cuts off the sense current. A constant current is supplied to the MR element 182 by the operational amplifier 168 and the resistors 166, 167, 169 and 183. In addition, the field effect transistor 170, the diode 171, the capacitor 1
72, the transistor 176, the resistors 173, 178, 174 and the level conversion circuit 181 cut off the sense current. Reference numeral 179 indicates a positive voltage and 168 indicates a negative voltage.

The output signal of the MR element 182 is the capacitor 2
8 and 29 removes DC component and input signal 3 of reed amplifier
It becomes 0.

FIG. 8 shows another embodiment of the control circuit for the sense current of the MR element. 160 is a sense current value signal, which is 20
0 indicates a D / A converter. The voltage set by the D / A converter 200 is cut off by the sense current switch circuit 201 by the sense current ON signal 180 and the level converter 215. The output of the sense current switch circuit 201 is amplified by the circuit of the transistor 205 and the resistors 202, 204 and 206, and controls the ON resistance of the field effect transistor 211. The current flowing through the MR element 214 is the field effect transistor 211, the transistor 213, the resistors 212, 21.
0, 209, and the Zener diode 208 control the constant current value determined by the ON resistance value of the field effect transistor 211 and the resistance 212. The output signal of the MR element has a direct current component removed by capacitors 28 and 29 and becomes an input signal 30 of the read amplifier.

[0021]

Since the sense current of the MR element mounted on the data head is cut off according to the control state, deterioration of the MR element can be prevented and the life can be extended.
Occasionally, the sense current value is set to be smaller than the optimum value depending on the control state, so that deterioration of the MR element can be prevented and it is effective in extending the life.

[Brief description of drawings]

FIG. 1 is a block diagram of a magnetic disk device of a servo surface servo system using an inductive element and an MR element in a data head of the present invention.

FIG. 2 is a timing chart of an example of sense current control of an MR element.

FIG. 3 is a timing chart of another example of sense current control of the MR element.

FIG. 4 is a timing chart of another embodiment of sense current control of the MR element.

FIG. 5 is an explanatory diagram of a positional relationship between an inductive element and an MR element of a data head.

FIG. 6 is an explanatory diagram of a configuration of a slider that forms an inductive element and an MR element.

FIG. 7 is a sense current control circuit diagram of the MR element.

FIG. 8 is a sense current control circuit diagram of the MR element.

FIG. 9 is a block diagram of an embodiment of positioning control using a servo signal on a servo surface and a servo signal on a data surface.

[Explanation of symbols]

17, 19 ... MR element, 20 ... Inductive element, 2
3 ... Sense current switch, 25 ... Constant current circuit.

Claims (7)

[Claims] 1. A magnetic recording disk has a recording surface for recording data and a recording surface for recording servo signals, and detects a data head equipped with an inductive element for writing data and an MR element for reading and a servo signal. In a magnetic disk device that uses an inductive element for the servo head,
During the control of moving the data head to a target data track by the servo signal read by the servo head, a sense current is not passed through the MR element, and a sense current is passed only during writing or reading of data. A magnetic disk device characterized in that 2. The sensing of the MR element according to claim 1, wherein during the control of moving the data head to a target data track by the servo signal read by the servo head and after the writing or reading of data is completed. A magnetic disk device in which a current value is set to a value smaller than an optimum value and a sense current value is set to an optimum value while writing or reading data. 3. A magnetic recording disk has a recording surface composed of an area for recording data and an area for recording a servo signal, and a recording surface for recording a servo signal, and an inductive element for writing data and a data and servo signal are recorded. In a magnetic disk device using a data head having a read MR element for detection and an inductive element as a servo head for detecting a servo signal, control for moving the data head to the vicinity of a target data track is performed by the servo head. Controlled by the servo signal read by the inductive element of, the control for positioning the data head at the center of the target data track, the high frequency component of the servo signal detected by the inductive element of the servo head, and the data Low frequency of servo signal read by MR element of head The servo current added with the components is used for controlling, and the sense current of the MR element is energized from the control of positioning the inductive element or MR element of the data head at the center of the data track to the end of data reading and writing. A magnetic disk drive characterized by the above. 4. The sense current value of the MR element is smaller than the optimum value during control of moving the data head to the vicinity of a target data track and after reading and writing of data is completed. Value, and the inductive element or MR of the data head at the center of the data track.
A magnetic disk device that optimizes the sense current value during the time when data reading and writing are completed from the control of positioning the element. 5. A magnetic recording disk comprising a data recording area and a servo signal recording area, and a magnetic disk device using a data head equipped with a write inductive element and a read MR element. In step 1, the sense current value of the MR element is controlled by the servo signal read by the MR element of the data head during the control of moving the data head to the vicinity of the target data track and after the reading and writing of data are completed. Is set to a value smaller than the optimum value, and the sense current value is set to the optimum value from the control of positioning the inductive element and the MR element of the data head to the center of the target track to the end of data reading and writing. And a magnetic disk device. 6. A plurality of magnetic recording disks are disks comprising a data recording area and a servo signal recording area, and a plurality of data heads equipped with a write inductive element and a read MR element are used. In the magnetic disk device, the servo signal read by the MR element of one of the plurality of data heads causes
From the control of moving the data head to the center of the target data track until the reading and writing of data is completed, the sense current of the MR element is supplied, and after the reading and writing of data is completed, it remains constant. A magnetic field is characterized in that a sense current is made to flow through an MR element of another data head for a certain period of time and a servo signal detected there is inputted to perform positioning control sequentially by the servo signals of a plurality of data heads. Disk device. 7. The sense current value of the MR element according to claim 6, while the plurality of data heads are sequentially switched and the positioning control is performed by the servo signal from each MR element at constant time intervals, the sense current value of the MR element is set to an optimum value. A magnetic disk device in which the sense current value of the MR element other than is set to a value smaller than the optimum value.