Method and apparatus for testing and setting magnetic field strength of permanent magnets in magnetic bubble domain modules

• US 4,158,811 A
• Filed: 06/27/1977
• Issued: 06/19/1979
• Est. Priority Date: 06/27/1977
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Naden, Rex A., Lee, Gene D., Li, Hsiao-Yuan, Stephenson, Alvis D. Jr.
• Primary Examiner(s): Corcoran, Robert J.
• Application Number:
  US05/810,148
• Time in Patent Office: 722 Days
• Field of Search: 324/210, 324/205, 365/1, 365/2, 29/574, 29/588, 29/593, 29/604, 361/143, 361/147
• US Class Current: 324/210
• CPC Class Codes: G01R 33/1207 Testing individual magnetic storage devices, e.g. records carriers or digital storage elements functional testing G06F11/00, G06F11/28
• CPC Class Codes: G11C 19/085 Generating magnetic fields therefor, e.g. uniform magnetic field for magnetic domain stabilisation

Abstract

Method and apparatus for testing and setting the field strength of permanent magnets in a magnetic bubble domain chip module, wherein the final molded module is formed to contain a pair of longitudinal slots which run through the module on opposite sides thereof. The module is inserted, via said slots, onto conducting members of a magnetic bubble module testing apparatus. The conducting members effectively provide one turn coils on each side of the module. Current is induced in these coils in such a way as to either add to or subtract from the bias field provided for the magnetic bubble domain chip by the permanent magnets of the module. The module is tested to determine the upper and lower operating levels of the bias field for effective operation of the chip, and the device is remagnetized to set the bias field of the module in the center, or optimal point, of the bias margin.

Claims

1. Apparatus for establishing the magnetic bias field strength within an optimum range of the permanent magnet structure for a shielded magnetic bubble domain module having a pair of elongated slots extending through the module on opposite sides thereof, said apparatus comprising:

magnetic field generating means operably associated with said magnetic bubble domain module but separate therefrom and including conducting members adapted to be temporarily moveably inserted within the magnetic bubble domain module through the slots therein and oriented with respect thereto to vary the magnetic bias field of the magnetic bubble domain module;

current source means electrically connected to said magnetic field generating means for selectively providing a constant electrical current at any one of a plurality of magnitudes of constant currents to the conducting members of said magnetic field generating means; and

said magnetic field generating means providing a magnetic bias field within the magnetic bubble domain module at a selected field strength in response to energization of said conducting members thereof by a constant electrical current of a selected magnitude from said current source means.

2. Apparatus as set forth in claim 1, and further including analyzer means operably associated with said magnetic bubble domain module for testing said magnetic bubble domain module via evaluation and analyzation of said module during the establishment of an optimum magnetic bias field strength for the permanent magnet structure.

3. Apparatus as set forth in claim 2, further including:

support means for supporting a magnetic bubble domain module during the testing, thereof and

contact means operably associated with said support means and adapted to contact the signal leads of the magnetic bubble domain module for supplying electrical signals to and receiving electrical signals from the signal leads.

4. A magnetic bubble domain module comprising:

a tubular housing of magnetic-shielding material,

a permanent magnet structure mounted within said tubular housing,

a molded body of insulating material substantially filling said housing,

a magnetic bubble domain chip substructure including at least one magnetic bubble domain chip embedded in said insulating body, and

said insulating body having first and second recesses extending along opposite sides thereof and cooperating with said housing to define elongated slots adapted to accept conducting members of an apparatus for performing tests on the magnetic bubble domain module temporarily moveably inserted within said slots during testing.

5. Apparatus for establishing the magnetic bias field strength within an optimum range of the permanent magnet structure for a shielded magnetic bubble domain module, said apparatus comprising:

magnetic field generating means operably associated with said magnetic bubble domain module but separate therefrom and including conducting members adapted to be temporarily disposed along the opposite sides of the magnetic bubble domain module and oriented with respect thereto to vary the magnetic bias field of the magnetic bubble domain module;

current source means electrically connected to said magnetic field generating means for selectively providing a constant electrical current at any one of a plurality of magnitudes of constant currents to the conducting members of said magnetic field generating means; and

said magnetic field generating means providing a magnetic bias field within the magnetic bubble domain module at a selected field strength in response to energization of said conducting members thereof by a constant electrical current of a selected magnitude from said current source means.

6. A process for establishing the magnetic bias field strength of the permanent magnet structure for a magnetic bubble domain module within an optimum range, said process comprising the steps of:

selectively providing a plurality of constant electrical currents at respective different magnitudes to a magnetic field generating means in operable association with the magnetic bubble domain module,

generating a plurality of magnetic bias fields within the magnetic bubble domain module at selected different field strengths corresponding to the respective magnitudes of said plurality of constant electrical currents in response to the respective energizations of said magnetic field generating means by the plurality of constant electrical currents,

determining the range of upper and lower magnetic field strengths from the plurality of generated magnetic bias fields of different field strengths between which said magnetic bubble domain module operates, and

magnetizing the permanent magnet structure to set the magnetic bias field strength thereof at a magnitude lying in the range of magnetic field strengths as determined.

7. A process as set forth in claim 6, further including:

connecting the signal leads of said magnetic bubble domain module to analyzer means, and

receiving signals from said magnetic bubble domain module in response to energization thereof via said signal leads to test said magnetic bubble domain module during a simulated operation thereof controlled by said analyzer means.

8. A process as set forth in claim 6, further including

establishing the optimal magnetic bias field strength of the permanent magnet structure for the magnetic bubble domain module within the range of magnetic field strengths as determined, and

thereafter magnetizing the permanent magnet structure to set the magnetic bias field strength thereof at the optimal magnitude.

9. A process as set forth in claim 6, wherein the plurality of constant electrical currents are selectively provided to the magnetic field generating means by applying successive different magnitudes of constant current to said magnetic field generating means at a predetermined time interval.

10. A process as set forth in claim 6, wherein the magnetic bubble domain module has a pair of elongated slots extending through the module on opposite sides thereof, said process further including:

initially inserting conducting members of the magnetic field generating means within the slots in the magnetic bubble domain module wherein the conducting members are oriented with respect to the magnetic bubble domain module to vary the magnetic bias field thereof in response to energization of the conducting members, and

thereafter selectively providing the plurality of constant electrical currents at respective different magnitudes to said conducting members in generating the plurality of magnetic bias fields within the magnetic bubble domain module at selected different field strengths.

15. A process as set forth in claim 6, further including producing an analysis printout indicating the non-functioning areas of said magnetic bubble domain module relative to the optimal bias field strength in response to signal outputs received from said magnetic bubble domain module for each of the constant electrical current magnitudes provided to said magnetic field generating means.

11. Apparatus for establishing the magnetic bias field strength within an optimum range of the permanent magnet structure for a shielded magnetic bubble domain module having a pair of elongated slots extending through the module on opposite sides thereof, said apparatus comprising:

magnetic field generating means operably associated with said magnetic bubble domain module and including conducting members adapted to be inserted within the magnetic bubble domain module through the slots therein and oriented with respect thereto to vary the magnetic bias field of the magnetic bubble domain module;

said conducting members comprising

first and second bar members, each of said bar members being an elongated flat strip of metal folded upon itself to define a J-shaped configuration including a long primary bar and an inturned short secondary bar, and

the inturned short secondary bars of said conducting members being adapted to be received within the slots of the magnetic bubble domain module;

current source means electrically connected to said magnetic field generating means for selectively providing a constant electrical current at any one of a plurality of magnitudes of constant currents to the conducting members of said magnetic field generating means; and

said magnetic field generating means providing a magnetic bias field within the magnetic bubble domain module at a selected field strength in response to energization of said conducting members thereof by a constant electrical current of a selected magnitude from said current source means.

12. Apparatus for establishing the magnetic bias field strength within an optimum range of the permanent magnet structure for a shielded magnetic bubble domain module having a pair of elongated slots extending through the module on opposite sides thereof, said apparatus comprising:

magnetic field generating means operably associated with said magnetic bubble domain module but separate therefrom and including conducting members adapted to be temporarily moveably inserted within the magnetic bubble domain module through the slots therein and oriented with respect thereto to vary the magnetic bias field of the magnetic bubble domain module;

current source means electrically connected to said magnetic field generating means for selectively providing a constant electrical current at any one of a plurality of magnitudes of constant currents to the conducting members of said magnetic field generating means;

support means for supporting the magnetic bubble domain module during the testing thereof, said support means comprising

a block of insulation material, said block having a surface provided with a transverse channel defining raised portions on opposite sides of said channel, each of said raised portions having a plurality of parallel lead slots therein extending to the respective edges of said channel, and said channel being adapted to receive the magnetic bubble domain module with the signal leads thereof received in said plurality of lead slots during the testing thereof;

contact means operably associated with said block and adapted to contact the signal leads of the magnetic bubble domain module for supplying electrical signals to and receiving electrical signals from the signal leads;

said magnetic field generating means providing a magnetic bias field within the magnetic bubble domain module at a selected field strength in response to energization of said conducting members thereof by a constant electrical current of a selected magnitude from said current source means; and

analyzer means operably associated with said magnetic bubble domain module and electrically connected to said contact means for testing said magnetic bubble domain module via evaluation and analyzation of said module during the establishment of an optimum magnetic bias field strength for the permanent magnet structure.

13. Apparatus for establishing the magnetic bias field strength within a optimum range of the permanent magnet structure for a shielded magnetic bubble domain module having a pair of elongated slots extending through the module on opposite sides thereof, said apparatus comprising:

magnetic field generating means operably associated with said magnetic bubble domain module but separate therefrom and including conducting members adapted to be temporarily moveably inserted within the magnetic bubble domain module through the slots therein and oriented with respect thereto to vary the magnetic bias field of the magnetic bubble domain module;

current source means electrically connected to said magnetic field generating means for selectively providing a constant electrical current at any one of a plurality of magnitudes of constant currents to the conducting members of said magnetic field generating means;

support means for supporting the magnetic bubble domain module during the testing thereof;

contact means operably associated with said support means and adapted to contact the signal leads of the magnetic bubble domain module for supplying electrical signals to and receiving electrical signals from the signal leads, said contact means comprising

a printed circuit board, one side of which is engageable with said support means,

a plurality of conducting tabs extending from said one side of said printed circuit board,

a plurality of narrow-line conductors disposed substantially parallel along the surface of said one side of said printed circuit board and contacting said plurality of conducting tabs, and

an edge connector located along one edge of said one side of said printed circuit board and contacting said plurality of narrow-line conductors;

said magnetic field generating means providing a magnetic bias field within the magnetic bubble domain module at a selected field strength in response to energization of said conducting members thereof by a constant electrical current of a selected magnitude from said current source means; and

analyzer means operably associated with said magnetic bubble domain module and electrically connected to said narrow-line conductors on said printed circuit board by said edge connector for testing said magnetic bubble domain module via evaluation and analyzation of said module during the establishment of an optimum magnetic bias field strength for the permanent magnet structure.

14. Apparatus as set forth in claim 13, wherein said contact means further includes:

first and second bifurcated prong members extending from said one side of said printed circuit board, said first and second bifurcated prong members respectively electrically contacting said conducting members of said magnetic field generating means; and

a transverse elongated conductor electrically connecting said first and second bifurcated prong members.