CN1371479A - Method and apparatus for testing magnetic head elements - Google Patents
Method and apparatus for testing magnetic head elements Download PDFInfo
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- CN1371479A CN1371479A CN 00812274 CN00812274A CN1371479A CN 1371479 A CN1371479 A CN 1371479A CN 00812274 CN00812274 CN 00812274 CN 00812274 A CN00812274 A CN 00812274A CN 1371479 A CN1371479 A CN 1371479A
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- magnetic head
- magnetic field
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- head element
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/455—Arrangements for functional testing of heads; Measuring arrangements for heads
Abstract
The present invention includes a method and apparatus that will permit the identification of damaged magnetic head elements. One aspect of this invention includes an electromagnetic structure (10) having a core (12), a plurality of electrical windings (14), and an air gap (13) adapted to receive a head stack assembly. The coils may be connected to a power source (16) and series resonant driver (22). Some embodiments of the present invention may further comprise a controller (20) operably connected to the series resonant driver and adapted to compensate for a variation in a magnetic field strength across the air gap. Another aspect of the present invention involves a method of testing a magnetic head element. One embodiment of this method includes the steps of measuring the head's output in response to an externally applied magnetic field, Fourier transforming the output signal, and using the resulting power levels to calculate a value indicative of a distortion in the head's output.
Description
Technical field
The present invention relates to a kind of in HSA (magnetic head storehouse assembly) or SHS (single magnetic head suspension) device of testing magnetic head elements.Specifically, the present invention relates to a kind of method and apparatus of measuring and estimating the puppet-non-symmetrical features of magnetic head element.
Background technology
Computer hard disc driver generally includes the magnetic head that is used to read and write magnetic recording element (hard disk).These magnetic heads are typical ingredients of magnetic head storehouse assembly (HAS), also comprise to hard disk writing the element of magnetic variationization and the element of the magnetic variationization that playback head is write previously.Typical writing component comprises interior thin film conductor around soft magnetic pole piece; Typical reading component is magnetic resistance (MR) or big magnetic resistance (GMR) bar, and when the changes of magnetic field of magnetic resistance bar, the magnetic resistance of magnetic resistance bar also changes.
Usually, the manufacturer tests their HAS, with the HAS that guarantees only to hold pack into disk groups and hard disk driver.A kind of conventionally test method is used expensive " universal stage " test machine identification " bad " magnetic head,, this method require HAS to be loaded into to be installed on the test machine " on the disk tester storehouse.One of determinant attribute that these universal stage testers are measured is that orbit averaging is asymmetric, (TAA, it is asymmetric also to be referred to as the orbit averaging amplitude, or TAAA).TAA measures the asymmetric property of magnetic head to the positive negative part of a series of amplitude responses that write on the magnetic variationization on the test tracks.Just, the TAA measurement come the self-test disk groups before write the asymmetry of track readback signal.TAA is typically expressed as track peak-to-peak amplitude V
P-pNumber percent.If the absolute value of TAA surpasses a specific preset value, representative value is ± 15%, just add " bad " label to magnetic head.TAA greater than ± 15% generally will arouse attention, because the super range applications of error correction code algorithms and/or product failure be in a default soft error rate standard, asymmetry may influence drive performance.
A problem of conventional universal stage method of testing is to exist requiring to pack into HAS and/or disk groups any time.Cause physical injury risk it cause production loss and manufacturer's cost to increase.Another problem of this method is the time loss of loading procedure.This problem had both reduced on the production line quantum of output of the driver parallel rotary test machine of installing of business men of seeking survival again.
Clearly, need a kind of improved method of testing of no longer require to pack into operation or expensive universal stage tester.
Summary of the invention
The present invention includes hardware, exciting method, data aggregation, operating process and can discern the software that the problems referred to above magnetic head is arranged.The present invention uses these components and parts to set up the method for a kind of HSA of test, and it does not need to pack into and operates and expensive universal stage.
An aspect of of the present present invention is a kind of device that is used for testing magnetic head elements, is made up of an electromagnetic structure, comprises a plurality of electric windings of magnetic core, is fit to hold the air gap of magnetic head element.Power supply is operably connected to a plurality of electric coils, and the series resonance driver is operably connected to power supply.Some embodiment of the present invention also comprises the controller that is operably connected to the series resonance driver and is fit to compensate the change of magnetic field strength of passing through this air gap.
The present invention relates to a kind of method of testing magnetic head elements on the other hand, method comprises the following steps: magnetic field is added to the output signal of magnetic head element, measurement magnetic head element, calculate the power level of fundamental frequency signal and multiple harmonic signal, utilize power level computation distortion indicated value.Certain embodiments of the invention also comprise the step of accepting or refuse head stack according to this distortion indicated value.Provide the step in magnetic field need prepare an electromagnetic structure,, utilize the power supply that links to each other with the series resonance driver in a plurality of coils, to produce electric current comprising magnetic core, a plurality of electric winding, air gap.
Third aspect present invention relates to a kind of system of testing magnetic head elements.This system comprise around magnetic head element produce the Computer Processing apparatus of device, the deal with data in magnetic field, the memory storage, second device that first device, the deal with data of collecting data from magnetic head element produces magnetic head element output distortion indicated value of storage data on storage medium.
Fourth aspect present invention relates to a kind of method that detects the defectiveness magnetic head element, the embodiment of this method comprises:, in magnetic structure, insert magnetic head element, magnetic structure comprises conducting element, induction current in conducting element, thereby magnetic structure produces the magnetic field around head stack, and the magnetic field of generation is relevant with induction current, simultaneously the output signal of sense of control induced current and measurement magnetic head element.
Characteristics of the present invention and advantage have provided " good/bad " appraisal procedure of a kind of TAA of being similar to, but it does not need pack into the disk groups and do not require expensive universal stage tester with HSA.With reference to following description, claim, accompanying drawing, so that understand this and other characteristics of the present invention, aspect and advantage better.
Description of drawings
Fig. 1 is the electromagnetic exciting device embodiment skeleton view of magnetic head storehouse component tester.
Fig. 2 is that data are collected and data analysis embodiment block scheme.
Fig. 3 is the curve map of the time-changes of magnetic field of one-period.
Fig. 4 is the first buffering magnetic head voltage output curve diagram that response diagram 3 magnetic fields are produced by magnetic head element.
Fig. 5 is the second buffering magnetic head voltage output curve diagram that response diagram 3 magnetic fields are produced by magnetic head element.
Fig. 6 is the present invention's " distortion % test result and universal stage TAA test result comparison diagram.
Specific embodiments
Here disclosed the present invention of specific embodiments under the condition of disk groups of needn't packing into HSA, has realized common most final head test that uses the universal stage test.People know, if magnetic field is commonly used to simulate the magnetic variation data on recording disc, and (for example: sine) vertically act on HSA with suitable form, may pass through the mathematical analysis of simulated cushioned magnetic head voltage (BHV) output of head stack, the measurement of obtaining the output signal asymmetry.Therefore, the present invention can provide " good/bad " appraisal procedure of a kind of TAA of being similar to, but it does not need the disk groups of packing into HSA.
The present invention is divided into three major parts, simulates the electromagnetic activation structure of MR during (1) test and is used to optimize the necessary Electron Excitation circuit that requires performance; (2) method of optimization sample data collection, it comprises the necessary software of realizing collecting the MR output that applies influence of magnetic field; (3) method of the deal with data of the effective output that from some attribute test of relevant magnetic head performance, produces.(1) electromagnetic activation structure Fig. 1 is the skeleton view that is designed to test down the calutron 10 when encouraging HSA.Calutron 10 includes the magnetic core 12 of air gap 13, a plurality of coils 14 that link to each other with power supply 16, and in certain embodiments, calutron 10 can be the structure type of " square C ".Because its simple in structure, well-known electromagnetic property, such structure is that we wish.Yet other electromagnetic structure that can produce magnetic field in air gap is in this scope of invention.
In the practice, power supply 16 produces electric current in coil 14, and this electric current produces the magnetic flux by magnetic core 12 and air gap 13 successively.The manufacturer inserts HSA in space 13, simulate magnetic recording element with this magnetic field.
The calutron 10 of embodiment that Fig. 1 describes comprises: (1) size A, highly added a little allow clearance and determined by the HSA of test; (2) the long-pending B of pole surface, design provides the non-relatively distortion magnetic line of force of two interpolars enough large tracts of land, makes the action part of placing HAS under the test in the straight magnetic field line post easily, and area B also is used for setting up the maximum secting area of HSA device; (3) size C, decided by following difference between the two: (i) air gap line of force that coil is produced directly influences minimum maximum length, (ii) reduce total magnetic resistance, minimum length, therefore improved efficient; (4) dimension D, decided by following difference between the two: (i) offer the maximum length of size E, enough length (ii) reduces the minimum length of the total magnetic resistance of structure to avoid magnetic line of force distortion between the area B.
The hope material of magnetic core 12 should have following properties: (1) high osmosis and high saturation are used for efficient and suitable magnetic flux carrying capacity; (2) high resistance, the eddy current losses when being used for minimizing the AC mode driving; (3) low remanent magnetism when HSA inserts or withdraws from test position, makes the HAS component exposed give the magnetic field part minimum between pole surface.A kind of suitable material is the polycrystalline ferrite with high osmosis and low remanent magnetism.This material is why welcome be because its satisfy above standard, aboundresources, relatively cheap.Yet other electromagnetic material is within the scope of the invention.
In certain embodiments, 600Hz sinusoidal signal excitation electromagnetic structure-10 by power supply-16 generation, adopt sinusoidal signal to be because when magnetic head by medium on during changes of magnetic field, the magnetic flux density that sinusoidal signal can the emulation magnetic head be seen, and can obtain the dynamic response of testing magnetic head.Adopting the 600Hz frequency is because of its compatible 60Hz and 50Hz signal source, and higher frequency is beneficial to elimination direct current ground unrest/influence.Yet, also be in the scope of this embodiment such as other waveforms such as square wave, triangular wave and other frequency.
Number of turn N around the coil of electromagnetic structure-10 is arbitrarily.Yet, one skilled in the art will appreciate that Amp and select to have the gap A of requirement relevant with the number of turn of the power supply 16 of requirement.Increase turn number N and will increase the magnetic field intensity that particular power source 16 produces.Similarly, reduce turn number N and will weaken the magnetic field intensity that particular power source 16 produces.
The field intensity peak value is controlled by the voltage V of power supply-16 generation that is inversely proportional to coil-16 resistance
P-p, as shown in Figure 1, in an embodiment, can make necessary driving voltage minimum by the resonant excitation device-22 of connecting.The electromagnetic structure-10 that this driver-22 allows to be energized produces high field intensity on given voltage.Some key advantage of these motivational techniques is: (1) excitation power supply size and weight minimum; (2) can use non--conventional penultimate amplifier; (3) radiation and Conducted Electromagnetic Interference minimum are disturbed minimum near responsive electronic installation.
This series resonance driver-22 usefulness one capacitor-18 comes the inductance of compensating coil-14 and magnetic core-12, and the selection of capacitor C should be satisfied the circuit resonance operation.Just power supply-16, electric capacity-18, coil-14, magnetic core-12 constitute a rlc circuit.If satisfy: C=1/L ω
2, then circuit starting of oscillation, L is the inductance of coil/magnetic core member here, ω is the frequency of power supply-16.Under such capacitance condition, the capacitive reactance of capacitor-18 is the inductance of bucking coil/magnetic core member, and it makes the impedance minimum of electromagnetic structure-10.
Again with reference to embodiment illustrated in fig. 1, the magnetic field intensity by space-13 can change with the upright position.When near the electromagnetic structure vertical centre, owing to such effect appears in the magnetic line of force loss that increases.In order to compensate this influence, some embodiment can be in conjunction with a controller-20, and according to which magnetic head among the current HAS just tested, controller 20 is controlled the voltage that power supplys 16 produce.Some controller-20 can be the feedback assembly of the analog or digital control algolithm of realization standard.Yet, can adjust and keep power supply 16 P-to-P voltage other the device also in this scope of invention.
Certain embodiments of the invention use collimation technique to determine suitable peak-to-peak voltage.These embodiment can use an autonomous device to measure the output of each magnetic field, position, space-13 or witness mark HAS assembly.The data of this calibration process can be offered controller-20 and be used to adjust power supply-16 voltage according to the magnetic head element position.In other words, utilize computing machine or similar device to calculate suitable correction factor, no matter the upright position of the magnetic head among the HAS how, guarantees that the vertical component of the horizontal center of magnetic field jaw (magnetic jaws) is approximately constant.
One skilled in the art will appreciate that the peak-to-peak intensity in magnetic field is the function of ac-excited peak-to-peak voltage.Therefore, the magnetic field intensity of the device of testing at this embodiment will be followed the sinusoidal voltage waveform that AC power 16 produces, and be proportional to the voltage that is added to coil-14.Because each specific magnetic head design all has the most responsive certain bias current point, certain embodiments of the invention can be adjusted the power supply peak-to-peak voltage when using controller-20 test specific device.This bias current particular value depends on certain products magnetic head or the design of manufacturer's magnetic head structure.(2) data sampling and collection
Fig. 2 has represented a suitable data sampling and collection algorithm, and at square 50, the HSA that the operator places test is between the surperficial B of electromagnetic structure-10 in the space.At square 52, the operator starts power supply-16, produces magnetic field in the space between the surface, and embodiment of the invention induced field as shown in Figure 3.
Certain embodiments of the invention can comprise a selectivity time delay 56 li of squares.In some cases, this time will allow total system to determine to provide the degree of acceptable measuring accuracy and repeatability.Decision parts required time is inversely proportional to the desired field intensity of excitation MR device usually and produces acceptable, analyzable BHV exports desired precision.Certain embodiments of the invention also will be controlled the frequency of sampling and phase place and guarantee that each n dimension group in the data matrix represents the actual cycle.Embodiment also will use hardware with magnetic field specified point synchrodata group starting point or use the software adjustment and the data of categorised collection in the cycle.In unsettled provisional application 09/120,995, Feb.19,2000 (current application number 09/505,033, Feb.16,2000) are entitled as " analyzing the nonequilibrium method and apparatus of motor ", have described a kind of suitable method in conjunction with reference example.Other method that can guarantee the data matrix of the actual HSA output of accurately expression also is possible and is in this scope of invention.(3) distortion measurement
With reference to figure 2, average output data array is duplicated into the t time keeping of second in square 62, do the fast Fourier transform (FFT) analysis by the CPU (central processing unit) of computing machine again.This analyzes and produces fundamental frequency signal and several harmonic signal performance number (decibel or dB).At square 64,, FFT harmonic data whole or that select calculates the % distortion value by being compared with the FFT data that are used for fundamental frequency signal.Use a large amount of formula to carry out this task.Yet simple relatively formula is welcome, such as with the simple function of the harmonic wave of the low order that elects, geometric function, gaussian weighing function etc.The example of intermediate means time domain waveform as shown in Figure 4 and Figure 5.They have represented that respectively the % distortion is 27.48 and 4.96 two kinds of situation data and curves.At square 66, accept or refuse HSA with this % distortion value.
The embodiment of the invention utilizes the FFTW subroutine library to carry out discrete Fourier transform (DFT) by computing machine.This subroutine library makes with the C programming language in Massachusetts Institute of Technology (MIT), and under the general public permissive condition of GNU, visit http://theory.Lcs.mit.edu/～fftw/ gets final product.Yet, one skilled in the art will appreciate that other discrete Fourier transform (DFT) algorithm is widely available and has potential application.
Fig. 6 shows is relation between the TAA absolute value measured of the % distortion that calculated by the embodiment of the invention and traditional universal stage.Find out that from general trend it is extraordinary adopting different measuring system effects.Suppose that absolute TAA measures＜the～15%, good magnetic head, the % distortion＜～10% also be magnetic head, importantly great majority are that good magnetic head also has been a magnetic head with the measurement of % distortion methods with measurements of universal stage TAA method.Similar with it, to be bad magnetic head measure with the % distortion methods with the measurement of universal stage method also is bad magnetic head.Do not need the HSA disk groups of packing into just can be finished the measurement of " qualified/defective ", (TAK) lacked 60-70% than the universal stage method time test period as a result.
The present invention is also welcome because detecting the edge magnetic head, and the universal stage rule can not.These characteristics are welcome to be because the manufacturer can be used for the quality control purpose to statistics.These characteristics are welcome also because the manufacturer can handle these driver classification.In other words, the manufacturer is used for the high-performance driver with the magnetic head of better performance, and relatively poor magnetic head is used for the low performance driver.Can help the manufacturer to reduce waste like this.
Some embodiment also can measure the phase differential between the synthetic electric signal of pumping signal and magnetic head.These embodiment are feasible because by the magnetic head of Electrostatic Discharge or inappropriate process control damage demonstrate with magnetic head require density different phase place.Especially GMR magnetic head.Do not recognize as yet that so far the universal stage method can diagnose this major issue.Other embodiment still can analyze the correlation intensity of various synthetic harmonic signals, to detect the ESD damage.
The invention provides many advantages that exceed known HSA method of testing and device.For example the present invention includes the method for assessment MR and GMR magnetic head element performance, the result compares with universal stage TAA measuring method, does not need the universal stage tester and pack operation on the HSA level.Other advantage of the present invention is to use sinusoidal magnetic strength curve, does not use stepping DC source of energization (ordinary representation " quasi static test ") and do not resemble the non-used exciting field of test of packing into of traditional HSA.The quasi dynamic test quasi static test more used than prior art more approaches the practical operation condition of HSA.
Although the present invention has been done detailed description above,, still can implement in other specific forms not breaking away under essence spirit of the present invention and the characteristic condition according to some embodiment.For example, although in this application that openly focuses on inventing, so that check MR and GMR magnetic head element at the HAS assembling stage, very clear, will allow described method to be applied in the lower-order section of slider, magnetic head balanced component (HGA) and other device assembly equivalently to some little modifications such as workholder, control electronic technology, connection, analysis software.The image data that these are used to analyze among the embodiment will be sampled from the output of the electron device that is connected to contact, lead, rubber-insulated wire.In addition, although this disclosed embodiment general using is programmable, the general purpose computing machine that is connected to analog to digital converter and data storage device, the present invention also can be realized by other hardware.Especially some big producer may wish with the specialized equipment replacement computer.
Above with accompanying drawing and character rendering the embodiment of the invention and characteristics and device, the device of fixing, install, paste or be connected to form a machine integral body about device of the present invention, unless specific (special) requirements is arranged, otherwise this device means and comprises traditional retaining element, such as machine screw, nut, web member, packing ring, anchor clamps, rivet, toggle, pin or the like.If allow, methods such as assembly also can be fixed with welding, friction, adhesion, distortion connect.Be electrically connected with the location-sensitive device and can form, comprise traditional parts and web member with suitable electron device and method of attachment.Unless specific (special) requirements is arranged, element manufacturing material of the present invention can be selected suitable material, such as metal, metal alloy, fiber, plastics or the like, and suitable production and processing method, such as methods such as casting, mold pressing, machine works.Anyly be intended to be convenient to describe, be not confined to the present invention or its parts to arbitrary position or direction in space with reference to all around, top and bottom, upper and lower.Therefore, embodiment described here explains and has considered all aspects, does not add any restriction, can determine scope of the present invention with reference to additional claim.
Claims (20)
1. the device of a testing magnetic head elements comprises: electromagnetic structure comprises magnetic core, a plurality of electric winding, is fit to hold the air gap of magnetic head element; Power supply is operably connected to a plurality of electric coils; The series resonance driver is operably connected to power supply.
2. by the described device of claim 1, it is characterized in that also comprising: controller is operably connected to the series resonance driver and is fit to the variation of the magnetic field intensity of passing through air gap is compensated.
3. by the described device of claim 2, it is characterized in that controller is fit to optimization magnetic head element response sensitivity.
4. by the described device of claim 2, it is characterized in that controller comprises that each head stack that is suitably in the magnetic head storehouse assembly provides the backfeed loop in preliminary election magnetic field.
5. by the described device of claim 1, it is characterized in that electromagnetic structure is fit to make efficient maximum, vortex flow minimum, remanent magnetism minimum.
6. by the described device of claim 1, it is characterized in that magnetic core made by the polycrystalline Ferrite Material of height infiltration, low remanent magnetism.
7. by the described device of claim 1, it is characterized in that the number of windings in a plurality of windings is determined by the magnetic field of air gap, power supply and requirement.
8. by the described device of claim 1, it is characterized in that electromagnetic structure has inductance and series resonance driver, the series resonance driver comprises the electric capacity that is fit to this inductance of balance.
9. by the described device of claim 1, it is characterized in that power supply is fit to provide sinusoidal voltage.
10. the method for a testing magnetic head elements comprises:
For magnetic head element provides magnetic field;
Measure the magnetic head element output signal;
Calculate the power level of fundamental frequency signal and a plurality of harmonic signals.
Utilize this power level computation distortion indicated value.
11., it is characterized in that further comprising by the described method of claim 10:
According to distortion indicated value refusal magnetic head element.
12., it is characterized in that providing the step of methods of magnetic field to comprise by the described method of claim 10:
The electromagnetic structure that comprises iron core, a plurality of coil, air gap is provided;
The power supply that utilization is connected in the series resonance driver produces electric current in a plurality of coils;
13., it is characterized in that providing the magnetic field step further to comprise by the described method of claim 12:
Adjust the position of electric current with the compensation magnetic head element.
14., it is characterized in that further comprising by the described method of claim 12:
Magnetic head storehouse assembly is placed in the air gap.
15., it is characterized in that providing the step in magnetic field further to comprise by the described method of claim 10:
For specific magnetic head element makes magnetic field the best.
16., it is characterized in that providing the step in magnetic field further to comprise by the described method of claim 10:
Utilize the controller compensation changes of magnetic field.
17., it is characterized in that the step of measuring output signal comprises by the described method of claim 10:
The a plurality of data points of sampling in a plurality of cycles;
A plurality of sampled points are stored in the data storage device.
18., it is characterized in that the step of measuring output signal further comprises by the described method of claim 10:
The frequency of synchronous a plurality of data points and phase place.
19. the system of a testing magnetic head elements comprises:
Device is used to produce the magnetic field around magnetic head element;
The Computer Processing apparatus is used for deal with data;
Memory storage is used for storing data on storage medium;
First device is used for collecting data from magnetic head element;
Second device is used for deal with data, to produce magnetic head element output distortion indicated value.
20. a method that detects the inefficacy magnetic head element comprises:
Magnetic head element is inserted electromagnetic structure, and electromagnetic structure comprises conducting element;
Induction current in conducting element, therefore, electromagnetic structure produces the magnetic field around magnetic head element, and the magnetic field of generation is relevant with induction current; And
The output signal of while sense of control induced current and measurement magnetic head element.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14371399P | 1999-07-14 | 1999-07-14 | |
| US60/143,713 | 1999-07-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1371479A true CN1371479A (en) | 2002-09-25 |
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ID=22505263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 00812274 Pending CN1371479A (en) | 1999-07-14 | 2000-07-14 | Method and apparatus for testing magnetic head elements |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP2003504790A (en) |
| CN (1) | CN1371479A (en) |
| AU (1) | AU6215200A (en) |
| WO (1) | WO2001004655A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101443844B (en) * | 2004-11-04 | 2011-07-27 | 新科实业有限公司 | Method and system for measuring modulation of sliding block float height of magnetic storage medium |
| CN104134445A (en) * | 2014-08-07 | 2014-11-05 | 兆讯恒达微电子技术(北京)有限公司 | Method and system for testing magnetic head through magnetic coupling method |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6738208B2 (en) * | 2001-10-30 | 2004-05-18 | Seagate Technology Llc | Microwave noise testing circuit for a disc drive |
| DE10229624A1 (en) * | 2002-07-02 | 2004-01-15 | Delphi Technologies, Inc., Troy | Magnetic sensor control method for master sensor control feeds magnetic-field generators with a time-variable voltage signal for feeding coils to create a magnetic field and parts of magnetic fields |
| US7150531B2 (en) | 2003-08-26 | 2006-12-19 | The Regents Of The University Of California | Autostereoscopic projection viewer |
| WO2006049353A1 (en) * | 2004-11-01 | 2006-05-11 | Samsung Electronics Co., Ltd. | The test system and method of the electric device |
| JP2008269681A (en) * | 2007-04-18 | 2008-11-06 | Hitachi Computer Peripherals Co Ltd | Device and method for measuring magnetic head characteristics |
| JP5933152B2 (en) * | 2012-05-21 | 2016-06-08 | 株式会社日立情報通信エンジニアリング | Magnetic device measuring apparatus and magnetic device measuring method |
| CN103245952B (en) * | 2013-04-28 | 2015-04-15 | 苏州长城开发科技有限公司 | Testing machine for head stack assembly piezoceramic micro-drive displacement |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5218296A (en) * | 1992-02-07 | 1993-06-08 | International Business Machines Corporation | Method and apparatus for determining at least one characteristic of a superconductive film |
| DE19514342C1 (en) * | 1995-04-18 | 1996-02-22 | Siemens Ag | Radio-interrogated current transducer for HV or MV appts. |
| US5939879A (en) * | 1996-07-23 | 1999-08-17 | Dynamics Research Corporation | Magnetic encoder for sensing position and direction via a time and space modulated magnetic field |
-
2000
- 2000-07-14 CN CN 00812274 patent/CN1371479A/en active Pending
- 2000-07-14 AU AU62152/00A patent/AU6215200A/en not_active Abandoned
- 2000-07-14 JP JP2001510011A patent/JP2003504790A/en active Pending
- 2000-07-14 WO PCT/US2000/019286 patent/WO2001004655A1/en active Application Filing
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101443844B (en) * | 2004-11-04 | 2011-07-27 | 新科实业有限公司 | Method and system for measuring modulation of sliding block float height of magnetic storage medium |
| CN104134445A (en) * | 2014-08-07 | 2014-11-05 | 兆讯恒达微电子技术(北京)有限公司 | Method and system for testing magnetic head through magnetic coupling method |
| CN104134445B (en) * | 2014-08-07 | 2017-06-16 | 兆讯恒达微电子技术(北京)有限公司 | Magnetic coupling method tests the method and system of magnetic head product |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6215200A (en) | 2001-01-30 |
| JP2003504790A (en) | 2003-02-04 |
| WO2001004655A1 (en) | 2001-01-18 |
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