JPH02121108A - Head positioning system for thin film magnetic head inspection instrument - Google Patents

Abstract

PURPOSE:To accurately position a head to be inspected at the corresponding track and to improve the inspecting reliability for a head having the small core width in its R/W jobs by applying correction every fixed time to the position shift of a position detecting head that are caused by the temperatures. CONSTITUTION:When the thin film heads 1-1 and 1-2 are continuously checked for a long time, a position detecting head 1-3 is moved by a carriage mechanism so that the difference signal between two position signals detected by the head 1-3 before the check is set at '0', i.e., the position error is equal to '0'. The corrected position of the carriage mechanism is detected by a laser length measuring instrument, and the data on this detection is recorded in a memory. Then the heads are inspected based on the position of the carriage mechanism. The position detecting accuracy is very high since the detecting accuracy of the laser length measuring instrument is extremely high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for positioning a head in a thin film magnetic head inspection apparatus, and more particularly to a method for correcting positional deviation due to temperature of a thin film head having a narrow core width.

[Prior Art] A magnetic head used in a magnetic disk device has a head core 1b in a casing 1a of the magnetic head 1, as shown in FIG.
is attached, and the tip IC of the core is slightly raised above the surface of the rotating magnetic disk 2 to perform information data writing/reading operations. The width W of the tip 1c is currently about 10 to 20 μm, and the track T is written with this width.

In the future, the density of magnetic disks will continue to increase, and in response to this, there is a possibility that the core width W will become 10 μm or less.

The performance of the magnetic head is inspected by a magnetic head inspection device during the manufacturing stage. During inspection, the head to be inspected writes data to appropriate tracks on the measurement disk.
This is done by reading out the information, but it is necessary that the head is correctly positioned on the track. Normally, in the case of conventional cores, the amount of positional deviation of the head is within an allowable range relative to the effective width of magnetization, so no particularly precise positioning measures are taken. In an actual device, since the head needs to follow each of a large number of tracks on the entire surface of the disk, positioning is performed by a servo system1), which is different from head inspection.

[Problems to be Solved] Inspecting a core width head in the future may require a long time. During this time, if the disk head and the arm that supports it expand or contract due to temperature, the width of the tip of the head is narrow, so the displacement with respect to the track cannot be ignored. This is called thermal off-track and reduces the reliability of inspection. On the other hand, in the conventional servo system, the servo data is 8 (clock circuit and data pattern G
It has a complicated configuration such as EN1 positive H link circuit and is not necessarily effective for head tester use. This is why a simple and precise positioning method that corrects positional deviation is desired.

[Means for Solving the Problems] The present invention is a head positioning method in an inspection apparatus in which data is written/read by a thin-film head to be inspected on appropriate tracks of a measurement disk rotated by a spindle. A position signal is input in advance to the track of the measurement disk by the position detection head, and this is read out to detect the positional deviation between the position detection head and the head to be inspected.The position detection head is moved by the carriage mechanism to detect the position deviation. 0, the corrected position of the carriage mechanism is detected by a laser length measuring device, data on that position is stored in a memory, and the head to be inspected is inspected at the position of the stored data. With respect to the positional deviation of the position detection head caused by temperature as time passes, the above correction is performed at regular intervals, data in the memory for the corrected position of the carriage mechanism is updated, and the inspection is continued.

In section h, the angle signal detected from the angle disk attached to the spindle and rotating at the same time as the measurement disk1)
, 2 with a phase difference of 180' from each other with a constant pulse width
generates a gate pulse train of 1) and uses the position detection head to
, two position signals having a phase difference of 180° according to the gate pulse train are respectively applied to two adjacent tracks of the measurement disk.

These two position signals are simultaneously read by the position detection head, and the difference signal is used to determine the positional deviation of the position detection head with respect to the center of the two tracks.

[Function] In the head positioning method described above, for continuous inspection in which the thin film head is shuttled for a long time, the difference signal between the two position signals detected by the position detection head becomes 0 before the inspection. In other words, the position detection head is moved by the carriage mechanism so that the positional deviation becomes zero, and the positional deviation is corrected to zero. The corrected position of the carriage mechanism is detected by a laser length measuring device, the data is recorded in a memory, and the inspection head is inspected based on this position. In this case, since the detection accuracy of the laser length measuring device is extremely high, the detection position is highly accurate.

Further, since both the position detection head and the test head are attached to the carriage mechanism and move simultaneously, the above correction also correctly positions the test head with respect to the test data track. 1) Even if the temperature of the head itself and the support arm changes and the head position shifts due to the passage of time, correction is made at regular intervals, the data in the memory is updated, and the inspection is performed at the updated position. continue.

Note that it is also possible to grasp the positional deviation of the head in time series using the data in the memory 1).

The above position signal is written in two adjacent tracks of the measurement disk by two gate pulse trains generated using the angle signal from the angle disk (1), and is read out by the position detection head. , a difference signal is generated 1), and each head is positioned relative to the track by moving each head using the carriage mechanism so that the difference signal becomes 0 as described above.

Embodiment FIG. 1 is a block diagram of an embodiment of a head positioning system for a thin film magnetic head inspection apparatus according to the present invention. In the figure, spindle 3 has two ff1ll constant disks 2-1.
．． 2-2 and angle disk 2-3 are attached, and each disk rotates in the same direction. Radiation I-1, 1-2 and position detection head 1-3 to the thin film to be inspected with respect to the measurement disk.
are provided, and each head is supported by a common carriage mechanism 5. The carriage mechanism 5 is driven by a suitable drive mechanism 53 such as a voice coil, and each head faces a predetermined track position. Here, the two to be tested henotodo 1
．． The test 2 is an up head corresponding to the lower surface side of the disk 2 and a down head corresponding to the upper surface side of the disk 2, which have different structures (1), and are to be inspected at the same time. Next, the index detection sensor 4-1. An angle detection sensor 4-2 is provided.

Positioning is performed 1γ prior to inspection work. A position signal for positioning is shown in FIG. 2, and the operation of each part will be explained using this together. Rotating angle disc 2-3 1),
An index (INDEX) signal indicating the starting point of a track is detected by an index detection sensor 4-1, and subsequently, a rotation angle (ANGLE) signal 3 of the disk is detected by an angle detection sensor 4-2. The angle signal is
This is a sensor output that divides one track into an appropriate number of equal parts. In the timing generator (GEN) 6, two gate pulse trains 'ro GATE and TI GATE having a phase difference of 180 degrees as shown in the figure are generated from the angle signal, and these are used to generate the write/read amplification Z (R /WAMP
)7 is controlled. Pulse oscillation W (O
3C) The pulse from 8 is written in the track To on the lower surface of the measuring disk 2-2 by the position detection head 1-3 under the control of To GATE, and then the pulse from TIGATE
The pulse controlled by T.

is written to track Tl adjacent to .

Next, in positioning, the position detection head 1-3 is placed near the center of the tracks To and TI, and the position signals of both tracks are simultaneously read out at the gates of To and T1, respectively. The read signal is T.

RDOUT, TI Indicated by RDOUT. These are level detectors (TQ) 9-1 and (Tt) 9-, respectively.
2, a voltage "O+V1" is output, and a differential voltage (v□ -vl) is determined by a differential circuit IO.

This differential voltage is input to the control device 11 and corrected by moving the carriage mechanism 5 using the drive mechanism 58 so that the differential voltage becomes zero. The corrected position of the carriage mechanism 5 is detected by the laser length measuring device 12, and the position data is stored in a memory provided in the control device 11.

After the above positioning is performed, the post-positioning measurement system 14, the R/WAMPI 3, and the heads to be inspected I-1, 12 perform inspection by writing/reading test data (1) using this position as a reference. When inspecting the head to be inspected continuously for a long time, the above correction is performed at regular intervals, and the corrected position of the carriage mechanism 5 is detected each time by the laser length measuring device 12 to update the data in the memory. death,
The inspection will continue.

[Effects of the Invention] As is clear from the above explanation, in the head positioning method according to the present invention, the position of the carriage mechanism that moves the head is corrected in a timely manner by the position signal, and the head to be inspected is correctly positioned on the corresponding track. be done.

The position of the carriage mechanism is precisely detected by a laser i1'III at fixed intervals before and during the inspection, and the data in the memory is updated to grasp the positional deviation in chronological order. With a simpler configuration compared to the servo system used in magnetic disk drives1), highly reliable R/W testing of narrow core width heads is possible with nJ
In addition, the time-series data is useful for analyzing the phenomenon of head position deviation with respect to temperature, and it is also possible to analyze the positional displacement of the spindle carriage as seen from the head.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the head positioning method of a thin-film magnetic head inspection apparatus according to the present invention, FIG. 2 is a time chart of the position signal in FIG. 1, and FIG. 3 is an explanatory diagram of the operation of the magnetic head. . DESCRIPTION OF SYMBOLS 1... Magnetic head, Ia... Head housing, 1b... Head core Nlc... Core tip, 1-1.12... Thin film head to be inspected (head to be inspected), 13. ...Angle detection head, 2...Magnetic disk, 2-1.2-2...dll+constant disk, 2-
3... Angle disk, 3... Spindle, 4-1... Index detection sensor, 4-2... Angle detection sensor, 5... Carriage mechanism, 5a... Drive mechanism, 6...・Timing generator, 7...
・R/WAMP, 8...Pulse oscillator, 9・
...Level detector, 10...Differential circuit, ■...Control device, 12...Laser length measuring device, 13...R
/WAMP, +4...Measurement system.

Claims (2)

[Claims] (1) In an inspection device that writes/reads data to/from a thin-film magnetic head to be inspected (hereinafter referred to as the head to be inspected) on an appropriate track of a measurement disk that is rotated by a spindle. A position detection head writes a position signal, reads the position signal, detects a positional deviation between the position detection head and the head to be inspected, and moves the position detection head using a carriage mechanism to eliminate the positional deviation. The corrected position of the carriage mechanism is detected by a laser length measuring device, the data of the position is stored in a memory, the head to be inspected is inspected at the position of the stored data, and the head to be inspected is inspected at the position of the stored data. The thin film magnetism is characterized in that the positional deviation of the position detection head caused by temperature over time is corrected at regular time intervals, and data in the memory for the corrected position of the carriage mechanism is updated. Head positioning method for head inspection equipment. (2) In the above, two gate pulse trains having a constant pulse width and a phase difference of 180° are generated from an angle signal detected from an angle disk mounted on the spindle and rotating at the same time as the measurement disk. , the position detecting head detects the two adjacent positions of the measuring disk.
The two position signals having a phase difference of 180° according to the gate pulse train are respectively written on the track, and the two written position signals are simultaneously read out by the position detection head, and the difference signal is obtained. 2. A head positioning method for a thin film magnetic head inspection apparatus according to claim 1, wherein the amount of positional deviation of said position detecting head with respect to the centers of said two tracks is determined by: