JPH05242617A - Head positioning circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent deterioration of a regenerative signal and to enhance the reliability of detecting the signal by storing an offset amt. between a read head and a write head in advance and performing a read by offsetting this amt. at the time of the read. CONSTITUTION:When the read head and the write head are provided in one slider, and positioning of the heads in a rotary type is performed, a positioning error signal 42 obtained from regenerative information of a servo head 31 is inputted to an adder 33. On the other hand, a signal for offsetting both head positions by an offset amt. corresponding to a track position is inputted in advance to a voltage generating circuit 35. Then, when an R/W gate signal 44 becomes active at the time of read operation, a track address 40 is inputted, and a positioning error correcting signal 44 corresponding to this track position is read out to be inputted to the adder 33. From the adder 33 a post correction positioning error signal 43 corrected in offset is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head positioning circuit for a magnetic disk device, and more particularly, a head drive mechanism of a rotary type and a read head and a write head
The present invention relates to a head positioning circuit for a magnetic disk device that includes separate elements.

[0002]

2. Description of the Related Art In the head of a conventional magnetic disk device, reading and writing are performed by one head. By the way, as the recording density of the magnetic disk device increases, the voltage of the read signal becomes smaller. For this reason, S for the impedance noise of the head and the circuit noise of the first stage of the reproducing circuit
The NR (signal-to-noise ratio) deteriorates and the error rate of read information deteriorates. As a measure for improving this SNR, the adoption of an MR head (magnetoresistive head) is considered. M
The R head is a conventional inductive head (ferrite,
The reproduction efficiency is high and a large output voltage can be obtained as compared with the MIG and the thin film head).

Since the MR head is for reproduction only, a conventional thin film head is used for writing. As for the arrangement of the MR head and the thin film inductive head, a separation type arrangement shown in FIG. 8 has been proposed. FIG. 8 is a view of one of the sliders 22 of the magnetic head as viewed from the slide surface. MR element 20
The thin film inductive head 21 and the thin film inductive head 21 are arranged on the head center line 25 with a distance D between the elements.

Most of the head drive mechanism of the small magnetic disk drive is a rotary type actuator.
FIG. 9 shows the position of the magnetic head in the rotary actuator. In FIG. 9, the magnetic head 4A is positioned on the inner track 3 of the disk 1, and the magnetic head 4B is positioned on the outer track 2. The magnetic heads 4A and 4B rotate around the center 8 of the head arm pivot while drawing an arc 5. Lines connecting the head arm pivot center 8 and the slider centers of the magnetic heads 4A and 4B are arm center lines 7A and 7B, which coincide with the slider center line 25 of FIG. This arm center line 7A, 7
B and tangent line 1 of the track arc at the head element position
The angle formed by 0 is called the yaw angle θ.

In the case of a rotary actuator, this yaw angle θ cannot always be set to 0 on the inner and outer tracks. Figure 8
As shown in, the recording track 27 is formed at an angle of the yaw angle θ from the slider center 25. At this time, MR
The center locus 28 of the element 20 is displaced by the distance of the offset δ between the R / W elements in FIG. δ is expressed by the following equation. δ = D · tan θ When the distance between the center of the head arm pivot 8 and the disk 1 is M and the track radius is r, the yaw angle θ is expressed by the following equation. θ = π / 2−COS ⁻¹ ((r ² + L ² −M ² ) / (2rL)) From the above, the offset δ between R / W elements monotonically increases with respect to the yaw angle θ, and the track radius r Represented as a function. To minimize the yaw angle θ over the entire track,
Generally, the yaw angle θ is designed to be 0 at the center track radius. At this time, the yaw angle θ of the innermost or outermost track is about 10 °. Distance between elements (D)
Is 5 μm, the offset δ between the R / W elements is 0.9 μm.

[0006]

In the conventional magnetic disk drive as described above, the recording density is 100 Mbit / i.
Since the element width 29 becomes 10 μm or less when nch ² or more, the offset amount is very large and the SNR
There is a problem in that it causes a loss and reduces the reliability of signal reproduction.

The present invention has been made to solve the above-mentioned problems, and prevents deterioration of the quality of reproduced signals,
An object of the present invention is to provide a head positioning circuit of a magnetic storage disk device which has high reliability of signal detection and high reliability and few errors.

[0008]

A positioning circuit for a magnetic storage disk apparatus according to the present invention which achieves the above object has a read head and a write head in one slider and includes a rotary type head positioning mechanism. In the head positioning circuit of the magnetic disk, the position error information obtained from the reproduction information of the positioning head has a correction means for correcting the position error amount between the read head and the write head at the read track position. Characterize. According to a second aspect of the present invention, the correction means reads the position error amount corresponding to the track address of the read head and the write head, and the signal corresponding to the position error amount output from the storage means. It is characterized in that it has a converter generated at the time of soaking, and an adding means for adding the output signal of the converter and the position error information. Claim 3
In the present invention, the correction means divides all tracks into a plurality of zones, and a conversion means which is generated at the time of reading a signal corresponding to the positional error amount between the read head and the write head in the zone to which the read track belongs. And an adding means for adding the output signal of the converter and the position error information.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. A head positioning circuit of a magnetic disk device according to an embodiment of the present invention includes a servo head 31 for reading head positioning information, a demodulation circuit 32 for outputting a position error signal 42 from output information of the servo head 31, and track address information. 40 as an input and an R / W gate signal 44, and when the R / W gate signal is active, outputs a signal / positioning error correction signal 41 corresponding to the track address information 40,
/ W turns off the output when the gate signal 44 is inactive
Voltage generating circuit 35, an adder 33 that outputs a signal obtained by adding the position error signal 42 and the positioning error correction signal 41 and a post-correction position error signal 43, and a post-correction position error signal 4
Compensation circuit 34 that performs band limitation and phase compensation for 3;
It comprises a power amplifier 36 which inputs an output signal of the compensation circuit 34 and supplies a corresponding current to the actuator 37, and an actuator 37 which drives a head for positioning.

FIG. 5 shows an assembled state of the head and the disk of the magnetic disk device. According to FIG. 5, the head / disk assembly is composed of four stacked disks 71, five head arms 74 stacked on the actuator 37, seven data heads 73 at the tip of the head arm 74, and the center of the stack. And a servo head 31 located in the area. The servo head 31 is a read-only head, and the data head 73 is composed of a thin film inductive head 21 for writing and an MR head 20 for reading, as shown in FIG.

When the yaw angle θ of the data head 73 is set to 0 at the track center portion, the correspondence between the R / W element offset δ and the track position becomes a curve as shown in FIG.

Next, the operation of this embodiment shown in FIG. 1 will be described. Since the servo head 31 is positioned by the actuator 37, the circuit of FIG. 1 forms a feedback loop. Then, it operates so that the post-correction position error signal input to the compensation circuit 34 becomes zero. When writing, R /
The W gate signal becomes inactive and the voltage generation circuit 35
The output of turns off. Therefore, the actuator 37 is driven and positioned according to only the position information of the servo head 31. During the reading operation, the R / W gate signal 44 becomes active. At this time, the voltage generation circuit 35 inputs the track address information 40, outputs the position error correction signal 41 for canceling the offset δ corresponding to the track position shown in FIG. 3, and adds it with the position error signal 42 by the adder. The position error signal 42 is a voltage signal substantially proportional to the position error distance. Assuming that the voltage corresponding to the position error 0 is 0 V and the coefficient between the position error distance and the voltage is Kθ [μm / V], the voltage generation circuit 35 generates the voltage δ / Kθ. Therefore, the voltage of the position error signal 42 becomes −δ / Kθ, and the servo head is positioned with the distance −δ offset.

As an example of the configuration of the voltage generating circuit 35, FIG.
Indicates. The voltage generation circuit 35 of FIG. 2 receives the track address information and outputs the position error correction information corresponding to FIG. 9 stored at that address, and the position error correction information thereof. The D / A converter 39 for converting the voltage into a voltage and the output of the D / A converter 39 to R
The switch 59 is turned on / off in response to the / W gate signal 44.

FIG. 4 shows another example of the configuration of the voltage generating circuit 35. The voltage generating circuit 35 of FIG. 4 is resistors 51, 52, 53, 54 having one ends connected to each other, the other end of the resistor 51 is connected to a power source, and the resistor 52 is connected to a negative power source via a switch 55. The resistor 53 is connected to the negative power source via the switch 56, and the resistor 54 is connected to the negative power source via the switch 57, and the resistors 51, 52, 53, 54 and the resistor 5 are connected.
It includes a switch 58 provided between the common connection point of 1, 52, 53, 54 and the position error correction output terminal. Here, the track information 40 includes a track information bit (n1) 61 for turning on / off the switch 55 and an ON / OF for the switch 56.
Turn ON / OFF switch (n2) 62 and switch 57
(N3) 63. R / W gate signal 44
Turns ON / OFF the switch 58. Here, the entire track is divided into eight zones for correction.

Zone division and switch 5 are shown in FIGS. 6 and 7.
The settings of 5, 56 and 57 are shown. FIG. 6 shows that the relationship between the offset δ between the R / W elements in FIG. 3 and the track position is evenly divided into eight offset amounts over the entire track, and the track range corresponding to the divided section is divided into the track zone (1), (2), (3), (4), (5), (6),
(7) and (8). The offset voltage and δ / Kθ corresponding to the center offset value of each track zone are V1, V2, V3, V4, -V4, -V3, -V2,-, respectively.
It was set to V1. Figure 7 shows switch 5 in each track zone
The ON / OFF states of 2, 53, and 54 are shown. At the time of writing, the switch 58 is turned off by the R / W gate signal 44.
It becomes F, and this voltage generation circuit 35 does not function. At the time of reading, the switch 58 is turned on by the R / W gate signal.
become. The track bits N1, N2 and N3 correspond to the switch 5 corresponding to the zone to which the read track belongs.
2, 53, 54 are controlled, and the position error correction signal 41 is generated in the combinations shown in Table 1.

[0016]

With the above-described structure, even when the rotary actuator type positioning mechanism is used for the head in which the read head and the write head are separated, the read head and the write head in the positioning track are preliminarily set. The offset amount is stored in the memory, and when read, the offset is offset by that amount before reading, preventing deterioration of the quality of the reproduced signal, increasing the reliability of signal detection, and providing a highly reliable and error-free magnetic disk device. Has the effect of providing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a head positioning circuit of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing one configuration example of the voltage generation circuit of FIG.

FIG. 3 is a graph showing a relationship between an R / W element offset and a track position.

FIG. 4 is a circuit diagram showing another example of the voltage generation circuit of FIG.

FIG. 5 is a diagram showing a mounted state of a disk, a head arm, and an actuator.

FIG. 6 is a graph obtained by dividing FIG. 3 into track zones.

7 is a table showing switch states of the voltage generating circuit 35 of FIG.

FIG. 8 is a layout view of R / W elements in a magnetic head slider.

FIG. 9 is an arrangement view showing the movement of the magnetic head on the disk.

[Explanation of symbols]

 1, 71 disk 2 outer track 3 inner track 4A, 4B magnetic head 20 MR head 21 thin film inductive head 22 magnetic head slider 31 servo head 32 demodulation circuit 33 adder 34 compensation circuit 35 voltage generation circuit 36 power amplifier 37 actuator 38 ROM 39 D / A converter 51, 52, 53, 54 Resistor 55, 56, 57, 58, 59 Switch 73 Data head 74 Head arm

Claims (3)

[Claims] 1. A position error information obtained from reproduction information of a positioning head in a head positioning circuit of a magnetic disk having a read head and a write head in one slider and having a rotary type head positioning mechanism. A head positioning circuit for a magnetic disk device, further comprising a correction means for correcting a positional error amount between the read head and the write head at a read track position. 2. The correction means generates at the time of reading the storage means for storing the position error amount corresponding to the track address of the read head and the write head and the signal corresponding to the position error amount output from the storage means. 2. A head positioning circuit for a magnetic disk drive according to claim 1, further comprising: a converter for converting the output signal of the converter and an adding unit for adding the position error information. 3. The converting means which divides all tracks into a plurality of zones and generates a signal corresponding to the positional error amount between the read head and the write head in the zone to which the read track belongs at the time of reading. 2. The head positioning circuit for a magnetic disk drive according to claim 1, further comprising: an adder that adds the output signal of the converter and the position error information.