JPH04205979A - Magnetic transducer and method for detecting floating hight - Google Patents

Abstract

PURPOSE:To attain high density in recording and reproduction by providing a sub-slider part supported by a main slider, having a detecting part which indicates the sub-slider part comes into contact with protrusions on the surface of a recording medium and thereby selecting the floating hight that allows to record and reproduce without being in contact with the protrusions. CONSTITUTION:This device is provided with the main slider 3 that floats by a wind pressure generated by the revolution of a recording medium, the sub- slider part 3a that is supported by the main slider 3, a variable means 8 that varies the hight of the sub-slider part 3a, and the detecting part 9 that indicates the sub-slider part 3a comes into contact with the protrusions produced on the face of the recording medium. Consequently, recording and reproduction are performed by pressing down the sub-slider face 4 down to the hight that is not in contact with the protrusions produced scatteredly on the face of the medium. Thus, the high density of recording and reproduction onto the disk is attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a recording/reproducing device such as a hard disk device, and a magnetic transducer such as a floating magnetic head used therein, and particularly relates to a method for detecting protrusions on a disk surface. The present invention relates to a magnetic transducer capable of performing the same functions as well as a flying height detection method equipped with the magnetic transducer.

[Prior Art and Problems to be Solved by the Invention] In a recording/reproducing apparatus using a magnetic recording medium disc (hereinafter also simply referred to as "medium" or "magnetic disk j"), it is possible to solve the problem without damaging the magnetic disk surface (recording surface). Information transmission to magnetic disks to ensure stable signal recording and playback.

During the recording operation of the number and the reproduction operation of the information signal from the medium, the magnetic gap part of the magnetic head can be traced while floating at a predetermined minute distance from the medium surface.
This has been practiced for a long time. In addition, to prevent the flying height of the magnetic head from changing significantly due to surface runout that occurs during rotation of the medium, or to facilitate contact start and stop operations and loading and unloading operations. , for example, Special Publication No. 44-18667
As disclosed in the above publication, a parent slider and a magnetic head are each made to float above the medium surface by the lift force generated on the air bearing surface by a thin layer of gas flow between the medium surface and the air bearing surface of the slider section. By providing two sliders of the child slider, it is possible to reduce fluctuations in the flying height of the slider to ensure a stable flying height, and to suppress vibrations and resonances induced in the slider support mechanism due to external disturbances. There have been many proposals regarding a parent-child type flying magnetic head device that enables stable flying operation (for example, Japanese Patent Laid-Open No. 62-99
Publication No. 967, JP-A No. 61-167681-16768
Publication No. 3, etc.) is well known.

In the parent-child floating type magnetic head device as described in Japanese Patent Publication No. 44-18667, etc., stable running operation of the magnetic head on the surface of the medium which is rotationally driven in a state with surface runout, It is common to try to improve the functionality of a floating magnetic head device from the viewpoint of eliminating mechanical resonance, etc., and in order to achieve high-density recording and reproduction, which has been in particular demand in recent years, It cannot be said that sufficient consideration has been given to ensuring that the floating magnetic head is stably floated extremely close to the recording surface of the medium.In such conventional devices, the magnetic head is suspended extremely close to the medium recording surface. It was difficult to keep the robot running stably.

That is, in the conventional parent-child type flying magnetic head device described in the above-mentioned Japanese Patent Publication No. 44-18667, etc., the flying surface of the parent slider is made up of three disks each having a diameter of 25 inches, making the device generally thick. The flying height of the child slider is also 2.
This is a relatively large value of about 5 μm, which is insufficient for high-density recording and reproduction, and because the device is relatively large, it is difficult to increase the access speed for moving between tracks.
Therefore, it has become necessary to take some measures to increase the access speed as seen recently.

Furthermore, the conventional magnetic transducer described above has the following drawbacks. In other words, hard disks for floating traveling are often subjected to surface roughening treatment called texturing or surface polishing, and unexpected protrusions may occur on the surface of the medium during the entire process of forming the final surface. Therefore, during normal recording and playback operations, a flying height was chosen that would allow recording and playback without contacting this protrusion, and the design was such that the (tip of the) magnetic helad was at least this height. However, as the flying height increases, recording characteristics and playback deteriorate, impairing high-density recording and playback, so it is desirable to run as low as possible, or if designed in such a way, contact with protrusions will occur and the head There was also a problem in that dust adhesion occurred due to contact, and in the worst case, it could lead to damage to the medium side.

Also, how many micrometers should the flying height be?fk3! Since there is no way to quantitatively know whether the media is i or not at the time of recording and playback, the standard value of the flying height determined when the medium was created was used.

However, this method does not ensure that there is no contact during actual recording and playback, and on the contrary, there may be too much margin in the flying height, so we manufactured many identical products and conducted destructive tests through many running tests. was also carried out to determine the acceptability of the set values.

On the other hand, there are means to measure the height of the protrusion mechanically or optically, but since the area that can be measured is narrow, a part of the medium surface is measured to estimate the entire image. In addition, no inventions or ideas have been made that take protrusion height checking and magnetic recording/reproduction into consideration at the same time, and when measuring protrusion height mechanically or optically, if the number of protrusions required is small, It is difficult to place the measurement detection part (because it is difficult to find the position)
, were often overlooked.

[Means to solve the problem]

The present invention provides: a main slider that floats due to wind pressure generated by the rotation of a recording body; a sub-slider section supported by the main slider; and variable means for varying the height of the sub-slider section within a predetermined range. A magnetic transducer characterized by comprising a detection section that indicates that the sub-slider section has come into contact with a protrusion formed on the surface of the recording medium, and a running height of the sub-slider section constituting the magnetic transducer. a voltage control circuit that supplies voltage to a control means (visible piezoelectric element) that changes the voltage within a desired range;

and a display section that displays the voltage waveform when the slave slider section contacts the protrusion or the number of contacts generated based on the voltage waveform, and by checking the number of contacts, etc., it is possible to detect the magnetic transducer. The above problem has been solved by providing a flying height detection method for detecting the flying height.

〔Example〕

In order to be able to simultaneously detect how protrusions (objects) of minute height that are dispersed on the surface of the medium are present during recording and reproduction, the magnetic transducer of the present invention has the following features: The biggest feature is that it has a built-in protrusion detection element (detection section). And as a protrusion detection element, HDD
(Hard Disc Drive) equipment (120
With media rotating at a high speed of 0rpH or higher, the height of protrusions can be detected from 0.03 to 0.3 μm, and the size of protrusions can be detected from 1 to 100 μm.
The contact time of the magnetic head with the protrusion becomes a very short pulsed signal on the order of μS. Therefore, in order to achieve the detection of such a pulsed signal, a pressure-sensitive ceramic is used as a detection element in a minute size (0.41In(11) x 0.4in).
f width) Xo, 21111f height)), added electrodes, and connected a video bandwidth preamplifier to detect the above pulses.

Hereinafter, specific examples of the magnetic transducer and the flying height detection method of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged perspective view showing an embodiment of the magnetic transducer of the present invention upside down, and FIG. 2 is an enlarged sectional perspective view taken along a plane passing through the center thereof. In both figures, the same components are given the same numbers, and 2 is, for example, a ferrite, an old G type recording/reproducing head (hereinafter also referred to as a "recording/reproducing head" or simply "head"), and 3 is, for example, a single crystal. The main slider is made of ferrite, 4 is the secondary slider surface, and 5 is zirconia.

Intermediate support ring made of sapphire etc. (hereinafter simply referred to as "ring"), 6 is made of stainless steel (thickness 10-15μ
m) front gimbal, 7 the same rear gimbal, 8 a flexible piezoelectric film bimorph made of resin film, for example (
9 is a pressure-sensitive ceramic element (hereinafter also simply referred to as "pressure-sensitive element"), 11 is a subassembly, 12 is a linkage made of stainless steel or piano wire, and 13 is an insulating material. Supporter, 15 top plate, 16 flexure, 18 adhesive, 25
is a ferrite core, 27 is a coil wound around this core 25, and g is a magnetic gap.

With this configuration, in order to accurately pick up pressure-sensitive phenomena within a short time, the pressure-sensitive element is moved from the 11M section (sub-slider surface 4) of the magnetic head 2 that comes into contact with a protrusion (protrusion) on the disk surface, which will be described later. The system leading to No. 9 is required to transmit high-speed pulsed mechanical shocks with little attenuation. That is, the vibration transmission speed is fast.

A relatively hard material must be formed to a small size and bonded to the pressure sensitive element.

In the magnetic transducer of the present invention, the material of the recording/reproducing head 2 is ferrite, and the total length is as small as about 0.81111.
Focusing on the fact that the above two conditions are met, the magnetic head 2
The pressure sensitive element 9 is arranged on the opposite surface of the slider surface (4). Thereby, the mechanical impact received on the slider surface is transmitted straight to the pressure sensitive element 9.

In a specific example, the output at the moment of contact with a protrusion having a protrusion height of about 0.12 μm is 2400 rpm.
The voltage was about 0.05 mV at a position of 55II11φ on the rotating disk surface at a linear velocity of 6.9 n/sec.

In addition, when the slider surface is further pressed against the protrusion by approximately 0.02 μm from the moment of contact, an output of approximately 0.2 mV can be obtained, ensuring a sufficient S/N ratio for measurement, providing high-quality impact detection. I was able to get the output.

One end of the pressure sensitive element 9 receives a mechanical shock pulse from the slider surface which is the detection end, or in order to extract this as the output voltage of the pressure sensitive element 9, the terminal end of the shock must be connected to the other end surface of the pressure sensitive element 9. Is there a need to form it?

In order to achieve this effect, a visible piezoelectric film bimorph (piezoelectric element) 8 is coupled to one end of the pressure-sensitive ceramic via a linkage 12, as shown in FIGS. 2 and 3. In addition, FIG. 3 is an enlarged central cross-sectional view showing the measuring section connected to the magnetic transducer 1 of the present invention, where 19 is an adhesive, E, E2 are electrodes, L, L2 are conductive wires, and 21 is a preamplifier. , 22 is a counter, 23 is an oscilloscope, 24
is an arithmetic processing unit.

By the way, there are two types of vertical movement that the head slider surface 4 receives. The first is that the main slider 3 and the slave slider section 3 rotate as the medium is rotated, which is determined by the surface accuracy of the medium.
This is the vertical movement of a (sub-slider surface 4), and the main slider 3 responds to relatively slow fluctuations, and the sub-slider portion 3a responds to relatively fast fluctuations, and the flying height of the magnetic head 2 increases. functions to keep constant. This is because the flying height of the slave slider section 3a can be easily controlled by the difference in the pressing force of the slave slider section 3a caused by the voltage applied to the piezoelectric element 8.

Second, since the size of the unexpected protrusion on the medium surface is small, the fluctuation time that the slave slider section 3a receives is short, and the slave slider section 3a remains unable to mechanically respond to vertical fluctuations.
This is the component by which the impact force is transmitted to the pressure sensitive element 9. Since the end of the pressure sensitive element 9 is supported by the linkage 12 and the piezoelectric element 8, the end of the impact is formed here, and only the impact pulse is picked up. Pressure sensitive element 9
When viewed from above, a kind of bypass circuit is formed.

The pulse output is amplified by a preamplifier 21 having a high impedance input terminal, and then supplied to an oscilloscope 23, where its waveform is observed.

The preamplifier output is also supplied to a counter 22, where the required time and the number of protrusions within a predetermined rotation are counted, and is also supplied to an arithmetic processing unit 24, where the signal is re-expressed in a more easily understandable form. will be displayed.

By the way, when picking up microscopic protrusions from the medium surface, it is important that the detection resolution is high. In this regard, in the magnetic transducer 1 of the present invention, the area resolution is determined by the area of the surface of the secondary slider section, and one of the features of the present invention is that the area is extremely small and the resolution is high. In the embodiment, in the structure of the recording/reproducing head 2 as shown in FIG. 4, the detection width d=350 μm and the detection length A in the running direction
= 350 μm, but if d = 150 to 450 μm, it falls within the practical range. In this figure, 26 is the core joint, which connects the two cores (both cores are half-closed).
25 are combined.

Further, since the flying height of the secondary slider section 3a that detects the protrusion can be varied by changing the voltage applied to the piezoelectric element 8, one of the features of the present invention is that the flying height of the detection surface can be controlled arbitrarily. It is one.

As a result, as shown in FIG. 5, protrusions randomly occurring on the surface of the recording medium can be classified into high protrusions (a), low protrusions (C), medium protrusions (b), etc. In FIG. 5, the arrow α indicates the direction of travel (rotation) of the media tray, and the same components as in FIG. Also, the two conductors are
I am compiling it into a book and drawing it. The frequency of occurrence of protrusions of each size is in the following relationship: a (small amount) < b < c (rapidly). By applying a voltage to the piezoelectric element 8, the slave slider section 3
When the flying height of a is high, only the relatively high protrusion a is detected, and when pushed down to the height of the protrusion, both protrusions a and b are picked up, and when the flying height is lowered to the protrusion C, naturally the protrusion a , b, and c are all detected.

A large amount of impact means that the tall protrusion a has strongly contacted the secondary slider surface 4, suggesting that the secondary slider surface 4 is easily damaged. Therefore, if the flying height is set low, dust will be generated from the scratched surface 4 or dust will adhere to the slave slider surface 4, damaging the magnetic head 2. Depending on the quantity counted by the counter 22, the display section of the arithmetic processing unit 24 displays characters or displays in multiple colors (for example, blue (0) - green (small quantity) - yellow (medium quantity) - It is convenient to configure the color to be orange (large amount) - red (contact with the medium surface).

FIG. 6 is an enlarged sectional view showing a state in which the slave slider surface 4 of the slave slider section 3a is retracted inward from the bottom surface 3b of the main slider 3. As can be understood by comparing this figure with FIG. By reducing the amount of deflection of the visible piezoelectric element 8,
The front gimbal 6 and the rear gimbal 7 are pulled upward (elastically). In this case, even the protrusion a is not counted, and the number of contacts is zero. The amount of deflection of the visible piezoelectric element 8 is changed by controlling the voltage applied to both pole faces of the piezoelectric element 8 by a voltage control circuit described later. In this figure as well, the same components as those in the apparatus shown in FIG. 5 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 7 and FIG. 8 show an example of the configuration of a voltage control circuit 10 (an example of teaching) for supplying a desired voltage to the visible piezoelectric element 8.
1 is a circuit diagram illustrating a circuit provided in, for example, a recording/reproducing device. By changing the voltage applied between the picture electrodes (terminals Fa, Fb) of the visible piezoelectric element 8 using the changeover switch SW, the amount of deflection of the piezoelectric element 8, that is, the amount of deflection between the slave slider surface 4 and the surface of the medium The minute distance is adjusted. In both figures, the reason why the resistor r2 is inserted is that if the piezoelectric element 8 is charged with residual electric charge, the slider surface 4 will be held due to the displacement corresponding to the electric charge, and the piezoelectric element 8 will be held. Since the response is slow, the resistance r2
This is to improve responsiveness by inserting and discharging each time.

In FIG. 7, the line S-S is the bottom surface 3 of the main slider 3.
b indicates the 1st digit, and h, i, and j represent the 1st digit of the slave slider surface 4 when the applied potential is negative (maximum value), zero, and positive (maximum value), respectively.
, Sw is a changeover switch that selectively applies multiple types of potential to the piezoelectric element 8, so that the secondary slider surface 4
is held in the range from h to j at each potential position. i place! For ease of use, it is assumed that the sub slider surface 4 normally protrudes beyond the bottom surface 3b of the main slider 3 and is in a state where the protrusion (a) can be detected. In actual use, the changeover switch Sv is initially located at the 11 terminal (contact) position in the circuits shown in FIGS.
...-n, O, +n, ...Switch to the + side (it is not necessary to use up to +1). At the moment the switch Sw is switched, it remains open until the next contact is connected.
Therefore, the charge stored in the piezoelectric element 8 is discharged through the resistor r2, and becomes 0 potential. That is, even if an attempt is made to lower the slave slider surface 4 one step below position 1h, it will be momentarily pushed down to position i, which is one step below. During this period, there is a possibility that the slider surface 4 comes into contact with the protrusion of a corresponding height.

In order to avoid such inconvenience, as shown in FIG. 8, the potential side (
-1 terminal) to the terminal Fa side via the resistor r1, so that even if the switch Sw is opened at the time of switching, it will not suddenly change to 0 potential and will be sequentially and continuously displaced to the lowest ground j. When the voltage control circuit 20 is configured,
- Good layer. With this configuration, 3.5 inch 40M
The number of protrusions in one rotation of the recording medium B is calculated as the number of revolutions 240.
When 0rpn 1- was measured, the following measurement results were obtained.

Note that the detection width d and detection length of the slave slider surface are both 3.
50 μm, and the unit of the flying height in Table 1 is also μm.

Table 1 In the above explanation, the preamplifier 21, counter 22 . Oscilloscope 23. Although each device of the arithmetic processing unit 24 may be configured separately, the preamplifier 21, the counter 22 . Oscilloscope 2
3. If at least one of the arithmetic processing units 24 is installed in a recording/reproducing device, the size of the protrusion can be measured every time the recording medium is replaced, and the most suitable flying height of the head can be determined for various media. A recording/reproducing main device capable of recording and reproducing can be realized. Furthermore, it is also possible to configure a measurement-only device that does not have a signal processing circuit for recording and reproduction, and that measures the amount and size of protrusions on the disk surface.

〔effect〕

As described above, the magnetic transducer and flying height detection method of the present invention have the following excellent features.

■ Recording and playback can be performed by pressing down the bottom surface of the magnetic transducer (sub-slider surface) to the limit height that does not contact the protrusions that are scattered on the medium surface.
High density reproduction can be achieved.

■The risk of damaging or damaging the helad slider surface of the magnetic transducer has been greatly reduced.

(2) Since the flying height can be varied, it is possible to perform a trial run at a flying height that corresponds to the height of the protrusions and find out how many protrusions of a certain height are present within one rotation or within a specific plane.

■The area of the secondary slider surface is small, and the detection width and detection length of the secondary slider surface that contacts the protrusion are short.
High resolution for detecting protrusions.

■Since the piezoelectric (pressure-sensitive) ceramic element used for impact detection is formed into an ultra-compact size, it is possible to detect even fast changes in speed, and the transmission from the detection side of the magnetic transducer is also
For example, the total length is 0.8IIl), so it can be picked up sufficiently even in high-speed operation.

■The state in which the recording medium is actually used for recording and playback (
Since protrusions can be sufficiently detected even at a rotation speed of 1,200 to 7,200 ru), the measurement can be carried out in a short time and is highly practical, and can also be used as a dedicated machine for measuring the quality of media.

■The sub-slider section is supported by the main slider and changes its flying height, and the flying height can be adjusted externally or with a voltage control circuit installed in the recording/playback head, allowing for structurally simple, stable, and easy-to-use control. be.

■Since the height and quantity of protrusions can be detected while simultaneously recording and reproducing on the medium, data useful for improving the medium and quality can be obtained immediately.

■It is possible to directly measure the relationship between signal degradation caused by protrusions.
It can also be applied to quality control to classify the usable range of media.

[Brief explanation of the drawing]

Fig. 1 is an enlarged perspective view showing an embodiment of the magnetic transducer of the present invention upside down, Fig. 2 is an enlarged cross-sectional perspective view taken along a plane passing through the center thereof, and Fig. 3 is an enlarged perspective view of an embodiment of the magnetic transducer of the present invention. FIG. 4 is an enlarged perspective view of the recording/reproducing head constituting the magnetic transducer of the present invention, and FIGS. 5 and 6 are views showing the detection of protrusions of the magnetic transducer. and an enlarged sectional view showing the non-detection state, FIG. 7 is a principle diagram showing the circuit and control operation for controlling the height of the slave slider surface of the magnetic transducer, and FIG. 8 is an improvement of the height control circuit. FIG. 2 is a circuit diagram showing an example. 1... Magnetic transducer, 2... Recording/reproducing head, 3...
・Main slider, 4... Sub-slider surface, 5... Intermediate support ring, 6... Front gimbal, 7... Rear gimbal, 8... Flexible piezoelectric element, 9... Pressure sensitive Ceramic element, 10.20... Voltage control circuit, 11... Subassembly, 12... Linkage,
13...Supporter, 15...Dog plate, 16
...Flexure, 18.19...Adhesive, 21...
- Preamplifier, 22... Counter, 23... Oscilloscope, 24... Arithmetic processing unit, 25... Ferrite core, 26... Core junction, 27... Coil,
D... Recording medium, El, E2... Electrode, L, , L2
...Conducting wire, a to C...Protrusion (part), g...Magnetic gap, r l, r2...Resistance, Sw... Changeover switch. Patent applicant: Victor Japan Co., Ltd.

Claims (3)

[Claims] (1) A main slider that floats due to wind pressure generated by the rotation of the recording medium, a sub-slider section supported by the main slider, a variable means for varying the height of the sub-slider section over a predetermined range, and 1. A magnetic transducer comprising: a detection section that indicates that the sub-slider section has come into contact with a protrusion formed on the surface of the recording medium. (2) The main slider is formed to fly at a height that does not contact the protrusions on the surface of the recording medium, and the sub-slider part is formed so that it does not come into contact with the protrusions from a position higher than the medium facing surface of the main slider. A control means is provided to change the running height in stages until the running, so as not to contact the recording medium surface itself, and furthermore, a detection section detects when the slave slider comes into contact with a protrusion on the surface of the recording medium. 2. The magnetic transducer according to claim 1, wherein the magnetic transducer is configured to output the impact as a voltage waveform. (3) A voltage supplied while changing the voltage over a desired range to the control means for changing the running height of the sub-slider part constituting the magnetic transducer according to claim 1 or claim 2. It is equipped with a control circuit and a display section that displays the voltage waveform when the slave slider section contacts the protrusion or the number of contacts generated based on the voltage waveform, and by checking the number of contacts, etc., the magnetic A flying height detection method characterized by detecting the flying height of a converter.