US3164811A

US3164811A - Saturable magnetic device

Info

Publication number: US3164811A
Application number: US10679A
Authority: US
Inventors: Robert E Boylan; Richard J Petschauer
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1960-02-24
Filing date: 1960-02-24
Publication date: 1965-01-05
Anticipated expiration: 1982-01-05

Description

Jan. 5, 965 R. E. BOYLAN ETAL 3,164,811,

SATURABLE MAGNETIC DEVICE Filed Feb. 24. 1960 INVENTORS ROBERT E. BOYLAN RICHARD J. PETSCHAUER United States Patent 3,164,811 SATURABLE MAGNETHC BEVECE Robert E. Boylan, St. Paul, and Richard I. Fetscha ier, Minneapolis, Minn, assignors to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed Feb. 24, 1960, Ser. No. 10,679 5 Claims. (Cl. 340-174) This invention pertains to magnetic devices and particularly such devices wherein transformation properties are related to conditions of magnetic saturation of a saturable element.

In many cases it is desired to have a maximum output operating with a core element unsaturated, but with a very minimum of output with the core element substantially saturated. However, in the past the coupling of input or drive windings to output windings irrespective of core action has given rise to undesired outputs with saturation conditions in the core. The present invention overcomes such disadvantages.

Briefly stated, in accordance with the present invention the input or drive (hereinafter drive) winding is in two distributed portions, and these wound oppositely. The output winding is positioned more intimately with the first portion of the drive winding than the remaining portion. The effective number of turns of the first portion of the drive winding is less than the effective turns of the remaining portion. The net result is that during saturation, the close coupling of the first portion of the drive winding, and the more remote coupling of the oppositely poled remaining portion thereof to the output winding, cause a nullification in effect upon the output winding. However, during non-saturation, the aforesaid remaining portion of the drive winding, with its larger number of turns, is more closely coupled, by virtue of the element, to the output winding, and the result is an appreciable induction in the output winding.

It is thus a principal object of the invention to provide for a maximum ratio of output to input with a core element unsaturated, but a minimum such ratio with the element saturated. Further objects of the invention and the entire scope thereof will become more fully apparent from the following detailed description of an illustrative embodiment, and from the appended claims. The illustrative embodiment may be best understood by reference to the accompanying drawings, wherein:

FIGURE 1 illustrates the embodiment of this invention showing a saturable magnetic element and the various windings associated therewith; and

FIGURE 1A illustrates the hysteresis characteristics of the magnetic element of FIGURE 1.

While the above illustrative embodiment involves the element in the form of a toroidal core, and used as a coincident current switch, clearly no limitation thereto is necessary or intended. The invention is applicable to auysituation where an element may be operated at times in saturated condition, and at other times less saturated.

Referring to FIGURE 1, there is illustrated a saturable magnetic element with associated drive and output windings. Two drive windings 12 and 14 are shown wound about the periphery of element 16. However, it is only necessary that there be one such drive winding, two being used where a coincident current application is desired. For this reason drive winding 14 which is of like turns array and like turns number to winding 12, has been shown dotted and will be discussed hereinafter in connection with coincident current operation. Winding 12 is a continuous distributed winding divided into two portions 18 and 2t by the relative winding directions thereof. Portion 18 is wound oppositely to portion 29 and therefore the field produced by current flowing in winding portion 18 is oppositely directed to that produced by current flow in portion 21 Output winding 16 is wound about element 10 in a side-by-side relation to Winding portion 18. Winding portion 18 has fewer turns than portion 2t} and preferably the total effective turns ratio of winding 18 to winding portion 20 is approximately 3:11. With this arrangement, it is seen that output winding 16 is more closely coupled, in the absence of element It) participation, i.e., in the absence of coupling from element lit, to the smaller winding portion 18, than to the larger winding portion 20.

The hysteresis characteristics of element 10 is shown in FIGURE 1A. The solid line represents the curve obtained when a high frequency signal is applied thereto, while the dotted line represents the curve when a low frequency drive signal is used.

To understand the operation of the circuit of FIGURE I assume the magnetization of element 10 has been biased to point 22 of FIGURE 1A by some biasing means not shown. The biasing means may, for example, be a current carrying winding inductively coupled to element 10 and activated by a suitable current source. When an input current pulse of insufficient magnitude to cause the magnetization of element 10 to become unsaturated is received on drive line 12, the magnetization thereof moves to some point, for example, point 24, which is still in the saturation region. As before mentioned, in the past the coupling of input or drive windings to output windings has given rise to undesired outputs with saturation conditions in the element because of residual permeability in the core and air coupling, i.e., the coupling between the drive and output windings even when the core is saturated is sufficient to cause an undesired output signal to be induced in the output winding. This coupling effect is overcome by the winding arrangement of FIGURE 1. As above described, the output winding 16 is more closely coupled to the portion of drive winding 12 of lesser number of turns, i.e., portion 18, than to the oppositely wound portion of greater number of turns, i.e., portion 20. Thus the coupling is greater between the output winding 16 and drive winding portion 18, than between output winding 16 and drive winding portion 20. Therefore, when a current pulse of insufiicient magnitude to drive the element out of saturation is applied on drive line 12, the field thereby produced from drive winding portion 18 is coupled to output winding 16 in a direction opposite to, and to a greater extent than is the field produced by the current pulse from drive winding portion 20. However even though winding portion 20 has a greater number of turns than winding portion 13, with a proper choice of turns ratio, the net effect relative to output winding 16 is a cancellation of fields and therefore negligible signal is induced in output winding 16. Thus when the element is operating'in a saturated region, an insignificant output results for any input insufficient to cause operation in the saturated region.

Next, consider the case when the element 10 is operated in its unsaturated region. Again assume that magnetization thereof is biased by means not shown into the saturation region to point 22, for example. When an input current pulse of sufficient strength to move the magnetization out of saturation, to point 26 for example, is applied to drive Winding 12, the corresponding flux change of element 10 causes a substantial output signal to be induced in output winding 16. In this case since the element is operating in its high incremental permeability region, a high percentage of the flux change produced i due to current flowing in winding portion 20 is coupled 3 Hence a large signal is induced in output winding 16. By properly choosing the number of turns in winding portions 18 and 25], as will now be understood from the foregoing, a maximum ratio of unsaturated output operation to saturated output operation may be obtained.

One important use of the above invention is in a magnetic core or element memory matrix which uses coincident currents as means for altering the states of these elements, although limitation to this use is not intended. In such matrices, predetermined elements are selected for writing infiorniation thereinto or reading information therefrom by activating drive lines inductively coupled thereto with drive pulses each of insuificient magnitude to cause these elements to change state. However, the total field produced by the coincidence of these pulses is sufiicient to cause the element or elements receiving this total field to change states, the magnetization thereof moving through the unsaturated portion of its hysteresis curve thereby inducing a substantial signal in an output winding coupled thereto. The elements that receive only a part of the total field have their magnetization moved only a portion of the way, along the hysteresis loop. This causes a signal, called a noise signal, to be induced in the output winding or windings thereto coupled. The practical size arrays, e.g., 32 x 32 x 32 elements, noise signals become quite important. The present invention as employed in such a matrix will considerably reduce these noise signals, an output signal being produced only when the elements thereof are operated in their unsaturated regions.

Referring again to FIGURE 1, the additional drive winding 14 is wound about the periphery of element 1% in coincidence with and sidc-by-side the drive winding 12. Winding portions 23 and 30 of winding 14 corre spond respectively to winding portions 18 and 2d of winding 12 and in the preferred winding arrangement winding portion 28 has the same number of turns wound in the same direction as winding portion 18 while winding portion 30 has the same number of turns wound in the same direction as winding portion 2.0.

Assume that a constant current is applied to a bias winding (not shown) which is inductively coupled to the element 10. This current produces a field which biases the magnetization thereof into saturation to point 22, for example. Provision is made for applying equal drive current pulses to windings 12 and 14 as is usual in some conventional coincident current memory systems, the pulses applied to each winding being termed half pulses. When these drive pulses are applied coincidently to windings 12 and 14, the total field caused thereby moves the magnetization out of the saturation region to a point such as point 26 in FIGURE 1A, producing a large change of flux through the output winding 16 and generating thereon a large output signal. This is called the full drive output. Since element is operating in its high incremental permeability region, a high percentage of the flux change due to the applied fields from winding

portions

20 and 30 is coupled to the output winding 16. Consequently the flux change due to the fields directed oppositely thereto'from winding portions 18 and 28 only cancel a portion of the flux change due to winding

portions

20 and 30. Thus a large output signal results.

However, when a half pulse is applied to only one of the drive windings, e.g., winding 12, the magnetization thereof is not moved out of saturation, but instead moves to some point 24 where the incremental permeability is low. Since output winding 16 is more closely coupled to winding portions 18 and 28 respectively having less turns than winding portions 29 and St the coupling therebetween is greater than the coupling between output winding 16 and winding

portions

24 and 30. By properly selecting the ratio of turns respectively between winding portions 18 and 20 of winding 12, and winding

portions

28 and 30 of winding 14, the fields caused by the half pulse flowing in either of the drive windings are canceled relative to output winding 16 and substantially no noise signal results. The illustrated turns ratio of 3:11 is exemplary or" an operable embodiment. Thus substantially no signal is produced on output winding 16 when only one drive line is activated with a half pulse, while a large signal is produced on output winding 16 when both drive lines are activated with half pulses and the ratio of full drive output to half drive output is increased over that obtainable with conventional winding distributions. Although only two drive windings have been employed in the above described coincident current use, it is clear that three or more drive windings may be used without departing from the scope of this invention. Therefore limitation to a two drive line employment is not intended.

Thus, it is apparent that there is provided by this invention a device in which the various objects and advantages herein set forth are successfully achieved.

Modifications of this invention not described herein will become apparent to those of ordinary skill in the art upon reading this disclosure. Therefore, it is intended that the material contained in the foregoing description and the accompanying drawings be interpreted as illustrative and not limitative, the scope of the invention being defined in the appended claims.

What is claimed is:

1. A method of using a device comprising a saturable magnetic element, a drive winding positioned for inductive coupling to said element, an output winding positioned for inductive coupling to said element, the output winding being positioned to be more closely inductive- 1y coupled irrespective of said element to a first portion of said drive winding than to the remaining portion thereof, and the respective portions of the drive winding being oppositely poled, said method including the step of magnetically saturating said element when a minimum output from said output winding is desired and maintaining said element in an unsaturated state when a predetermined greater output is desired.

2. A method of using a device comprising a saturable magnetic element, a first drive winding and a second drive winding positioned for inductive coupling to said element, an output winding positioned for inductive coupling to said element, the output winding being positioned to be more closely inductively coupled irrespective of said element to a first portion of said drive windings than to the remaining portions thereof, and the respective portions of the drive windings being oppositely poled, said method including the step of magnetically saturating said element by passage of current through both drive windings to so saturate the element when a minimum output from said output winding is desired, and reducing the current in at least one of said drive windings for maintaining said element in an unsaturated state when a predetermined greater output is desired, the method being such that the device may operate as a coincident-current device.

3. A saturable magnetic core matrix switch the combination comprising: a magnetic core; an input winding magnetically linking said core and having oppositely wound first and second portions; an output winding and a bias winding magnetically linking said core; said input winding second portion having substantially more turns than said first portion; said output winding wound about said core so as to provide substantially greater air coupling with said input winding first portion than with said second portion; the arrangement being such that when the magnetic state of said core is driven into saturation by a bias signal coupled to said bias Winding the close coupling of the input Winding first portion and the remote coupling of the input winding second portion, both with respect to the output winding, causes a cancellation of the induced noise signal in the output winding, but when the magnetic state of said core is driven into an unsaturated condition 'by an input signal coupled to said input winding the greater number of turns of the input e) winding second portion, as compared to the lesser number of turns of the first portion, acting through the high incremental permeability of the core causes an appreciable signal to be induced in said output winding.

4. A saturable magnetic core matrix switch, the combination comprising: a saturable magnetic core; an input winding magnetically linking said core and having oppositely wound first and second portions; an output winding and a bias winding magnetically linking said core; said input Winding first portion having substantially less turns than said second portion; said output winding wound about said core so as to provide substantially greater air coupling with said input winding first portion than with said second portion; the arrangement being such that when the magnetic state of the core is driven into saturation by a bias signal coupled to said bias winding the close coupling of the input winding first portion and the remote coupling of the input winding second portion, both with respect to the output winding, cause a cancellation of the induced noise signal in the output winding, which noise signal is caused by both air coupling and core coupling of the input winding first and second portions to the output winding, but when the magnetic state of said core is driven out of said saturated condition by an input signal coupled to said input winding the greater number of turns of the input winding second portion, as con1- pared to the lesser number of turns of the first portion, acting through the high incremental permeability of the core causes an appreciable signal to be induced in said output winding.

, winding portions, said first portion having substantially less turns than said second portion; said output winding inductively coupled to said first and second input windings so as to provide substantially greater air, coupling with said first portion than with said second portion; a bias Winding inductively coupled to said core; bias signal means coupled to said bias winding for selectively placing the magnetic state of said core in a first substantially saturated condition; substantially similar first and second half-select signal means selectively coupled to said first and second input windings, respectively; said first and second half-select signal means individually incapable of'driving the magnetic state of said core out of said first substantially saturated condition, but, when coincident, collectively capable of driving the magnetic state of said core out of said first substantially saturated condition into its condition of high incremental permeability; the arrangement being such that when the magnetic state of said core is placed in said first substantially saturated condition by said bias signal means the close coupling of said first and second input windings first portions and the remote coupling of said first and second input windings second portions, both with respect to the output winding, cause a cancellation of the induced noise in the output winding, which noise signal is caused by both air coupling and core coupling of the first and second input windings first and second portions to the output winding, when only said first half-select signal means is coupled to said first input winding drivingthe magnetic state of said core through the area of substantial saturation but not into the condition of high incremental permeability, but when said first and second half-select signal means are coincidentally coupled to said first and second windings the magnetic state of said core is driven into its condition of high incremental permeability causing an appreciable signal to be induced in said output winding.

References tfliteil in the file of this patent UNITED STATES PATENTS Johannesen Mar. 26, 1912 Elmen Dec. 31, 1918 OTHER REFERENCES

Claims

5. A SATURABLE MAGNETIC CORE MATRIX SWITCH, THE COMBINATION COMPRISING: A MAGNETIC CORE; AN OUTPUT WINDING INDUCTIVELY COUPLED TO SAID CORE; FIRST AND SECOND SUBSTANTIALLY SIMILAR INPUT WINDINGS INDUCTIVELY COUPLED TO SAID CORE WITH EACH INPUT WINDING HAVING FIRST AND SECOND WINDING PORTIONS, SAID FIRST PORTION HAVING SUBSTANTIALLY LESS TURNS THAN SAID SECOND PORTION; SAID OUTPUT WINDING INDUCTIVELY COUPLED TO SAID FIRST AND SECOND INPUT WINDINGS SO AS TO PROVIDE SUBSTANTIALLY GREATER AIR COUPLING WITH SAID FIRST PORTION THAN WITH SAID SECOND PORTION; A BIAS WINDING INDUCTIVELY COUPLED TO SAID CORE; BIAS SIGNAL MEANS COUPLED TO SAID BIAS WINDING FOR SELECTIVELY PLACING THE MAGNETIC STATE OF SAID CORE IN A FIRST SUBSTANTIALLY SATURATED CONDITION; SUBSTANTIALLY SIMILAR FIRST AND SECOND HALF-SELECT SIGNAL MEANS SELECTIVELY COUPLED TO SAID FIRST AND SECOND INPUT WINDINGS, RESPECTIVELY; SAID FIRST AND SECOND HALF-SELECT SIGNAL MEANS INDIVIDUALLY INCAPABLE OF DRIVING THE MAGNETIC STATE OF AID CORE OUT OF SAID FIRST SUBSTANTIALLY SATURATED CONDITION, BUT, WHEN COINCIDENT, COLLECTIVELY CAPABLE OF DRIVING THE MAGNETIC STATE OF SAID CORE OUT OF SAID FIRST SUBSTANTIALLY SATURATED CONDITION INTO ITS CONDITION OF HIGH INCREMENTAL PERMEABILITY; THE ARRANGEMENT BEING SUCH THAT WHEN THE MAGNETIC STATE OF SAID CORE IS PLACED IN SAID FIRST SUBSTANTIALLY SATURATED CONDITION BY SAID BIAS SIGNAL MEANS THE CLOSE COUPLING OF SAID FIRST AND SECOND INPUT WINDINGS FIRST PORTIONS AND THE REMOTE COUPLING OF SAID FIRST AND SECOND INPUT WINDINGS SECOND PORTIONS, BOTH WITH RESPECT TO THE OUTPUT WINDING, CAUSE A CANCELLATION OF THE INDUCED NOISE IN THE OUTPUT WINDING, WHICH NOISE SIGNAL IS CAUSED BY BOTH AIR COUPLING AN CORE COUPLING OF THE FIRST AND SECOND INPUT WINDINGS FIRST AND SECOND PORTIONS TO THE OUTPUT WINDING, WHEN ONLY SAID FIRST HALF-SELECT SIGNAL MEANS IS COUPLED TO SAID FIRST INPUT WINDING DRIVING THE MAGNETIC STATE OF SAID CORE THROUGH THE AREA OF SUBSTANTIAL SATURATION BUT NOT INTO THE CONDITION OF HIGH INCREMENTAL PERMEABLILITY, BUT WHEN SAID FIRST AND SECOND HALF-SELECT SIGNAL MEANS ARE COINCIDENTALLY COUPLED TO SAID FIRST AND SECOND WINDINGS THE MAGNETIC STATE OF SAID CORE IS DRIVEN INTO ITS CONDITION OF HIGH INCREMENTAL PERMEABILITY CAUSING AN APPRECIABLE SIGNAL TO BE INDUCED IN SAID OUTPUT WINDING.