US3573760A
Expired / Lapsed
US
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High density thin film memory and method of operation
Assignee: International Business Machines Corp
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Filing: 1968-12-16
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Granted: 1971-04-06
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Expires: 1988-12-16
Abstract
Abstract A multilayer, multithreshold magnetic film memory element is disclosed which consists of a number of superposed magnetic storage layers which share the same word and bit-sense lines. Operation of the element is essentially in the orthogonal drive mode and requires the application of different amplitude pulses on the word line to separately energize each of the storage films of the memory element. Thus, for readout of stored information, the amplitude of a succeeding read pulse increases relative to the amplitude of the preceding read pulse. Each ascending step in the read pulses provides sufficient magnetic field to overcome the rotational switching threshold of a storage film, but insufficient magnetic field to overcome the rotational switching threshold of the next storage film. For writing, each succeeding pulse after the initial pulse is lower in amplitude than the preceding pulse and is applied in coincidence with one bit pulse. Only one layer at a time is switched; the magnetization direction thereof being determined by the polarity of each bit pulse. Several embodiments of a multilayer magnetic elements are shown all of which are capable of storing multiple bits of information at the intersection of a single word line and a single bit-sense line. The method of operating multilayer memory elements in conjunction with an array of these elements is also disclosed.
Inventors
- 👤 Hsu Chang
- 👤 Kurt R Grebe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:38
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/02; G11C11/14; G09; G09F; G09F3/00; G09F3/04; G09F3/06; G11C11/16; G11C11/161; G11C11/165; G11C11/1673; G11C11/1675; G11C11/1693; G11C11/56; G11C11/5607; G11C5/00; G11C5/02; H; H01; H01F; H01F10/00
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
65 words
A method for writing into multibit, multifilm magnetic storage element comprising the steps of applying via orthogonally disposed conductors at least a pulse of decreasing amplitude and simultaneously applying a train of pulses each of positive or negative polarity during the first of which rotation of all the films of the multibit element occurs, each succeeding pulse rotating one less film than the preceding pulse.
Claim 2
Independent Claim
65 words
A method for writing into multibit, multifilm magnetic storage element comprising the steps of applying via orthogonally disposed conductors at least a pulse of decreasing amplitude and simultaneously applying a train of pulses each of positive or negative polarity during the first of which rotation of all the films of the multibit element occurs, each succeeding pulse rotating one less film than the preceding pulse.
Claim 3
Dependent Claim
19 words
A method according to claim 1 wherein said at least a pulse of decreasing amplitude is a sawtooth-shaped pulse.
Claim 4
Dependent Claim
19 words
A method according to claim 1 wherein said at least a pulse of decreasing amplitude is a step-shaped pulse.
Claim 5
Dependent Claim
22 words
A method according to claim 1 wherein said at least a pulse of decreasing amplitude is a train of decreasing amplitude pulses.
Claim 6
Dependent Claim
56 words
A method according to claim 1 further including the step: applying via one of said orthogonally disposed conductors at least a pulse of increasing amplitude to switch each of said films of said storage elements to successively induce a current representative of the storage state of each of said films in the other of said conductors.
Claim 7
Dependent Claim
19 words
A method according to claim 5 wherein said at least a pulse of increasing amplitude is a sawtooth-shaped pulse.
Claim 8
Dependent Claim
19 words
A method according to claim 5 wherein said at least a pulse of increasing amplitude is a step-shaped pulse.
Claim 9
Dependent Claim
22 words
A method according to claim 5 wherein said at least a pulse of increasing amplitude is a train of increasing amplitude pulses.
Claim 10
Independent Claim
83 words
A method for reading stored information from a multibit, multifilm magnetic storage element comprising the step of applying via one of a pair of orthogonally disposed conductors which are magnetically coupled to said storage element at least a pulse of increasing energy content to switch each of the films of said storage element in turn to induce successive signals in the other of said pair of conductors which are indicative of the binary state of each of the films of said storage element.
Claim 11
Independent Claim
83 words
A method for reading stored information from a multibit, multifilm magnetic storage element comprising the step of applying via one of a pair of orthogonally disposed conductors which are magnetically coupled to said storage element at least a pulse of increasing energy content to switch each of the films of said storage element in turn to induce successive signals in the other of said pair of conductors which are indicative of the binary state of each of the films of said storage element.
Claim 12
Dependent Claim
20 words
A method according to claim 9 wherein said at least a pulse of increasing energy content is a sawtooth-shaped pulse.
Claim 13
Dependent Claim
20 words
A method according to claim 9 wherein said at least a pulse of increasing energy content is a step-shaped pulse.
Claim 14
Dependent Claim
23 words
A method according to claim 9 wherein said at least a pulse of increasing energy content is a train of increasing amplitude pulses.
Claim 15
Dependent Claim
91 words
A method according to claim 9 further including the step of applying at least a pulse of decreasing energy content to said one of said pair of conductors while simultaneously applying a train of pulses containing pulses of positive or negative polarity to said other of said pair of conductors, all of said films of said memory element being rotated during the application of the first of said train of pulses, one less film being rotated during the application of a succeeding pulse than during the application of a preceding pulse.
Claim 16
Dependent Claim
82 words
A memory element comprising a first conductor, a second conductor disposed orthogonal thereto, means disposed at the intersection of said first and second conductors for storing a plurality of discrete bits of information, means for applying at least a pulse of changing amplitude coupled to one of said first and second conductors during both a read and write cycle, and means for applying a train of discrete pulses coupled to the other of said first and second conductors during said write cycle.
Claim 17
Dependent Claim
82 words
A memory element comprising a first conductor, a second conductor disposed orthogonal thereto, means disposed at the intersection of said first and second conductors for storing a plurality of discrete bits of information, means for applying at least a pulse of changing amplitude coupled to one of said first and second conductors during both a read and write cycle, and means for applying a train of discrete pulses coupled to the other of said first and second conductors during said write cycle.
Claim 18
Dependent Claim
36 words
A memory element according to claim 14 further including means coupled to the other of said first and second conductors during said read cycle responsive to the presence of currents in the other of said conductors.
Claim 19
Dependent Claim
18 words
A structure according to claim 14 further including means for closing flux disposed adjacent one of said conductors.
Claim 20
Dependent Claim
22 words
A structure according to claim 16 wherein said means for closing the flux includes magnetic films connecting the edges of said films.
Claim 21
Dependent Claim
16 words
A structure according to claim 16 wherein said means for closing flux is a magnetic keeper.
Claim 22
Dependent Claim
33 words
A memory element according to claim 14 wherein said means for storing a plurality of discrete bits of information includes a plurality of magnetic films dIsposed in magnetically coupled relationship with said conductors.
Claim 23
Dependent Claim
25 words
A memory element according to claim 19 wherein each of said plurality of films differs from the others by a difference in a physical characteristic.
Claim 24
Dependent Claim
25 words
A memory element according to claim 19 wherein each of said plurality of films differs from the others by a difference in a magnetic characteristic.
Claim 25
Dependent Claim
31 words
A memory element according to claim 19 wherein said plurality of magnetic films includes a plurality of pairs of magnetic films disposed symmetrically about one of said first and second conductors.
Claim 26
Dependent Claim
57 words
A memory element according to claim 19 wherein said plurality of magnetic films includes a plurality of magnetic films disposed adjacent one of said first and second conductors and a single magnetic film of a cross-sectional area at least equal to the cross-sectional area of said plurality of magnetic films disposed opposite said plurality of magnetic films.
Claim 27
Dependent Claim
24 words
A memory element according to claim 23 wherein each of said plurality of magnetic films and said single magnetic film have different cross-sectional areas.
Claim 28
Dependent Claim
16 words
A structure according to claim 19 wherein said plurality of magnetic films are uniaxial magnetic films.
Claim 29
Dependent Claim
16 words
A structure according to claim 19 wherein said plurality of magnetic film are biaxial magnetic films.
Claim 30
Dependent Claim
23 words
A structure according to claim 19 further including means for closing the flux disposed adjacent said word conductor and opposite said magnetic films.
Claim 31
Dependent Claim
24 words
A structure according to claim 19 further including means for closing the flux disposed adjacent said word conductor and spaced from said magnetic films.
References Cited (Backward Citations)
US3456247A
Cited
US3480929A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |