US3522442A - Switch - Google Patents

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Publication number
US3522442A
US3522442A US734465A US3522442DA US3522442A US 3522442 A US3522442 A US 3522442A US 734465 A US734465 A US 734465A US 3522442D A US3522442D A US 3522442DA US 3522442 A US3522442 A US 3522442A
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United States
Prior art keywords
windings
core
circuit
output
winding
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Expired - Lifetime
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US734465A
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English (en)
Inventor
Leslie R Wood
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Ferranti Packard Ltd
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Ferranti Packard Ltd
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Publication date
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/965—Switches controlled by moving an element forming part of the switch
    • H03K17/97—Switches controlled by moving an element forming part of the switch using a magnetic movable element

Definitions

  • FIG. 1 L. R. WOOD Aug. 4, 1970 SWITCH 2 Sheets-Sheet 1 Filed June 4. 1968 FIG. 1
  • FIG 25 FIG. 2A
  • FIGA A first figure.
  • Opposed sense series wound coils are located in a variable magnetic field.
  • a core is locatable in or out of one of the coils.
  • the other coil is arranged to provide an equal and opposite to the first in the varying field in either the core-in or core-out state of the first coil.
  • An unbalanced E.M.F. condition exists in the opposite core state of the first coil. Switching is therefore performed in the coil circuit by movement of the core and the coil circuit produces a substantial output in one state and substantially zero output in the other state.
  • This invention deals with a switching actuator or switch and has particular but not exclusive application to switches operating responsive to keyboard operation.
  • the device in accord with the invention is thought to be of principal value in replacing switches having connect-disconnect contacts, the most common of which is that type known as a micro-switch.
  • Such switches have been found, particularly in applications where the contacts have a high rate of operation (such as in a keyboard) to have a high failure rate due to contact wear, and various types of contact and mechanical failure.
  • the windings are arranged to produce, with such insertion of the magnetic core, from the series circuit a signal materially different from the zero potential. The result is that a switching or switch actuation function is performed by the insertion or withdrawal of the core'without any interruption or connection of the series circuit including the windings.
  • the insertion of the ferromagnetic core in some, but not all of the windings will act as the switching circuit, with the unbalance signal produced when the core is inserted, appearing as a connected AC source at the output of the series circuit in which the windings are connected; and the substantially null signal when the core is withdrawn appearing to the circuitry like a disconnected circuit.
  • the series connected windings may be connected to actuate another circuit like a transistor switch circuit to one state with the null output and the other state with the unbalance output.
  • tWo series connected electrical windings shall be wound in an opposite sense relative to the varying magnetic field, and of flux sensitivity to provide from the series circuit including the two windings in approximately null or zero output potential when neither winding is provided with a ferromagnetic core.
  • a ferromagnetic core is moved into one only of the opposed windings, and the varying magnetic field is applied, the resulting unbalance of the potential outputs of the two windings provides a net series circuit output signal relatively much larger than the net signal therefrom before insertion of the core.
  • Means connected for operation by the signal thus produced may thus be easily designed to discriminate between the signals produced with and without the core in one of the windings.
  • the switching function in the series circuit is achieved without the opening or closing of contacts. Wear and tear on contacts and operating arms is avoided. Spark and arc-over is avoided and this, it will be realized, has many advantages including the fact that the reciprocal movement of the cores to perform the switching function, may be performed in an explosive atmosphere where arcs or sparks would not be tolerated.
  • the opposed winding arrangement has substantial advantage over a single winding with a core removably insertable. With a single winding there is an unbalance in the winding circuit with or without the core (although of different magnitude). There is a diflicult and sensitive problem of distinguishing between the two states in the output circuit.
  • the Winding circuit is essentially of a low impedance.
  • a plurality of pairs of windings may be connected in series (as well as the windings in a pair being connected in series with each other).
  • the potential produced in an unbalanced pair of such series arrangement is therefore little affected by the connection, in series therewith, of a plurality of balanced pairs.
  • applicants invention includes an alternative arrangement to that already discussed.
  • all of the windings connected in a series circuit are, in one switching state, provided with cores and when so provided have a balanced (i.e. substantially null) output.
  • the cores are withdrawn from some but not all of the windings in the electric circuit, and the windings are arranged to provide a material net output from the series circuit during such withdrawal.
  • the first-described arrangement of having the balanced (null output condition with the movable core withdrawn) has however a number of distinct advantages over the lastdescribed arrangement where the null output condition occurs with the movable core inserted.
  • the total impedance will be less when several pairs of windings are used in series thus requiring the lowest input impedance of the attached sensing device.
  • FIG. 1 shows a broken view of a ten-digit keyboard incorporating the invention
  • FIGS. 2A and 2B are sections taken along the line 22 of FIG. 1.
  • FIG. 3 is a view along the line 3-3 of FIG. 2B;
  • FIG. 4 shows a variant of the embodiment shown in FIGS. 1-3.
  • FIG. 5 shows relative magnitudes of input and alternative output signals obtained with the circuit of FIG. 5.
  • FIG. 1 shows a magnetic circuit formed by a pair of substantially parallel magnetizable members joined adjacent one end by magnetizable material 12. An air gap 16 is therefore formed between unjoined portions of members 10. About some part of the magnetic circuit is an energizing winding 14 powered by a source (not shown) of variable current to produce a varying magnetic field in air gap 16. The length, spacing, and cross-sectional area of the ferromagnetic members is selected to provide an air gap 16 where a plurality of windings may be located and wherein ferromagnetic rods wholly or partially bridging the air gap 16 are selectively applicable to form cores for selected ones of the windings.
  • Ten pairs of windings 18 are, in the preferred embodiment, located between the members 10.
  • the members 10 and corresponding apparatus are however broken to indicate the positions of only the first, second, ninth and tenth of such windings.
  • the two windings 18A and 18B of each pair are connected in a series circuit and are wound in opposite senses relative to a magnetic field created by and between member 10 and the number of turns and other parameters of the winding are designed so that for vary ing fields produced, in the air gap 16, by energizing winding 14 the potentials created in the pairs of windings 18A and 183 with no core in either are substantially equal and opposite and the resulting output is substantially zero.
  • a ferromagnetic rod 24 Aligned with one winding 18A of each pair, is a ferromagnetic rod 24 slidably mounted in an aperture in the upper of the two spaced members 10 with the aperture and the slidable mounting aligned so that when a rod is de pressed it passes winding 18A only and approaches the other member 10 as closely as possible.
  • Means are schematically shown for mounting each rod and for biasing it to retracted position (i.e. out of coil 18A).
  • the biasing means here is shown as a compression spring 26 bearing at one end on the member 10 and at the other end On a key on the rod 24.
  • a key 28 At the upper end of the rod 24 is provided a key 28 for digital manipulation similar to the key provided for a typewriter.
  • Actuating means for the rod 24 may however take any manual or digital form.
  • the upper member 10, through which the rod slides is preferably relatively thick to give relatively good magnetic coupling with the rod 24. If desired the lower member 10 may be apertured to received the rod during its lowermost depression to give better magnetic coupling at the lower end also.
  • the rod 24 for the largest potential output will be designed to substantially bridge the air gap when inserted in the winding.
  • the buttons are numbered 1, 2, 3 0.
  • the buttons and rods instead of being biased by spring 26 may in actual practice he interlocked and/or moved from upper to lower location in any other desired manner.
  • the arrangement may be a normal decimal keyboard of the type that when any key is pressed, all others are raised. This is frequently combined with a clearing key for raising all lowered buttons.
  • Naturally any number of buttons and rods with corresponding rods 24 and pairs of windings 18A and 18B may be used. Pairs of windings are preferably located close to one another relative to other pairs to minimize distortion when the key is depressed.
  • the means of actuation of the ferromagnetic rods has no direct relationship to the invention as long as the actuation means allows the reciprocal movement of a ferromagnetic rod into and out of one winding of a selected group.
  • FIG. 5 is shown schematic indications of an A.C. input signal and the net output signal in a series circuit containing a pair of opposed windings 18A and 18B (as shown in FIGS. 2A and 2B) from an opposed pair of windings with (FIG. 2A) and without (FIG. 2B) the rod inserted in winding 18A.
  • the values of the input and al ternative output signals are of no relevance except for the relation of the net output signal from the series windings 18A and 18B, with and without the rod core in one.
  • the ratios of input to output signal strength will obviously depend on the turns ratio, the permeability and the geometry and physical properties of the magnetic circuit and cores.
  • the difference in output signal with and without the rod 24 in winding 18A is however clearly demonstrated v by comparing the approximately null output with the rod withdrawn and the material output with the rod forming a core for the winding 18A. It will be appreciated that the null may be made as small as desired by precise design of the opposed windings but that even without precise design the difference in output with and without the rod 24 in winding 18A may be made sufficient for most discriminatory circuits. With the rod out of the winding, the net output signal is substantially negligible, while with the rod 24 in the winding the net output signal is substantial. It will be noted that instead of an alternating current input, a pulse or any other varying level input may be used.
  • the use of the output which is selectively switched between levels which are easily discriminated from one another may be an actuating circuit, a memory, a transistor switch or any other circuit for energization.
  • a three or more series connected windings may be provided with some in opposed relationship to others and with the rod passing through selected ones of such windings so selected to provide an unbalance potential and hence an output when the rod is inserted in the selected windings.
  • the invention provides, means for performing a switching function without the necessity of opening and/or closing contacts.
  • the suggested decimal keyboard with ten such switching circuits is only one of many alternatives.
  • One or any plurality of such circuits may be connected.
  • the opposed series windings may be of any suitable arrangement as long as their effects are substantially balanced in output potential when neither winding has a core and materially unbalanced in output potential when a selected one of the windings has a core. It will be noted that it is immaterial what the geometric arrangement of a plurality of winding pairs is as long as the signal obtained in the unbalance condition is of measurable proportion with the apparatus used and hence easily distinguished from the small signal received in the balanced condition.
  • Either or both of the opposed windings may be split into more than one as long as the substantially null and unbalanced conditions in the pair of windings are maintained without and with the core respectively.
  • the opposed windings may have any number of turns conducive to substantial null and unbalanced output signals, the latter of sufficient magnitude. Thus with sufiicient energization, a single turn may be used for each winding in a pair.
  • more than one pair of windings may be used corresponding to one reciprocal rod with each pair of windings operating to supply signals of one of two states.
  • FIG. 4 An example of this is shown in FIG. 4 wherein a reciprocable ferromagnetic rod 124 is shown as connected to form (or not) the core for one of each of three pairs of opposed series connected windings 118A, 118B each pair arranged to provide substantially null output potential with the core withdrawn and each pair arranged to provide a material potential with the core in the respec' tive windings 118A.
  • the three windings aligned with the rod 24 in FIG. 4 may be concentrically or multifilar wound and the other three likewise and later connected in their series opposed circuits.
  • circuit may be designed alternatively to those above discussed by providing that all windings in a series connected circuit shall be provided to produce a null output when all windings in the circuit have cores and a material output when some but not all cores are withdrawn.
  • the magnetic circuit comprising members 10 joined by member 12 at one end, may be completed by providing a bridging member at the opposite end to give a complete ferromagnetic loop.
  • the added bridging member is provided with a winding similar to winding 14 but providing flux in the opposite sense.
  • the opposing fluxes both extend across the air gap where the windings are located and both supply flux to effect a potential output from the windings.
  • the two windings of opposed sense may be made by winding a winding in one sense of double the desired length for one winding in a pair and the two windings formed by bending the winding 180 on itself in the middle to provide two equal series connected oppositely wound windings side by side.
  • two windings may both be wound in the same helix and the opposite potential sense obtained by reversing their connections.
  • the same number of ones of said windings arranged to contemporaneously receive the core may be simultaneously bifilar or multifilar wound, the windings not receiving the core similarly treated and the connections in series opposed pairs made thereafter.
  • Means for performing a switching function comprising:
  • said windings being wound, oriented and connected to provide from said series circuit, when no winding has a magnetic core, approximately a null potential in response to said varying magnetic field;
  • Means for performing a switching function comprising:
  • said other of said windings being designed, wound and oriented to provide a potential approximately equal to and opposing the potential of said one of said one of said windings in one of said potential states and to be materially unequal to the potential of said one of said windings in the other of said potential states.

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  • Linear Motors (AREA)
  • Electromagnets (AREA)
  • Keying Circuit Devices (AREA)
US734465A 1968-06-04 1968-06-04 Switch Expired - Lifetime US3522442A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US73446568A 1968-06-04 1968-06-04

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US (1) US3522442A (de)
DE (1) DE1928294B2 (de)
FR (1) FR2010089A1 (de)
GB (1) GB1215114A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1980000882A1 (en) * 1978-09-27 1980-05-01 V Bernin Solid state noncontacting keyboard employing a differential transformer element
US4283714A (en) * 1979-08-08 1981-08-11 Texas Instruments Incorporated Magnetic keyboard system
US4401986A (en) * 1979-12-26 1983-08-30 Texas Instruments Incorporated Position sensor and system
US4494109A (en) * 1978-09-27 1985-01-15 Bernin Victor M Noncontacting keyboard employing a transformer element
US5066951A (en) * 1988-10-28 1991-11-19 Mannesmann Kienzle Gmbh Circuit arrangement for adjusting the triggering point of an inductive keyboard

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2905282C2 (de) * 1979-02-12 1982-05-27 W. Gessmann GmbH, 7105 Leingarten Schaltgerät, das aufgrund einer mechanischen Bewegung eine elektrische Ausgangsgröße erzeugt
US4398180A (en) * 1980-06-26 1983-08-09 International Standard Electric Corporation Contactless keyboard
DE4411758B4 (de) * 1994-04-06 2006-04-13 Siemens Ag Vorrichtung zur Erkennung einer mechanischen Berührung zweier Bauteile, insbesondere für Kraftfahrzeuge
JPH10228314A (ja) * 1997-02-14 1998-08-25 Nippon Signal Co Ltd:The トランス結合による信号伝送系の監視装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2347315A (en) * 1940-08-02 1944-04-25 Ferrocart Corp Radio receiver
US3054976A (en) * 1958-11-18 1962-09-18 Schaevitz Engineering Differential transformer
US3142762A (en) * 1960-01-22 1964-07-28 Kelk Ltd George Magnetically actuated switch device
US3313877A (en) * 1964-07-10 1967-04-11 Walter G Finch Electronic organ keying device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2347315A (en) * 1940-08-02 1944-04-25 Ferrocart Corp Radio receiver
US3054976A (en) * 1958-11-18 1962-09-18 Schaevitz Engineering Differential transformer
US3142762A (en) * 1960-01-22 1964-07-28 Kelk Ltd George Magnetically actuated switch device
US3313877A (en) * 1964-07-10 1967-04-11 Walter G Finch Electronic organ keying device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1980000882A1 (en) * 1978-09-27 1980-05-01 V Bernin Solid state noncontacting keyboard employing a differential transformer element
US4300127A (en) * 1978-09-27 1981-11-10 Bernin Victor M Solid state noncontacting keyboard employing a differential transformer element
US4494109A (en) * 1978-09-27 1985-01-15 Bernin Victor M Noncontacting keyboard employing a transformer element
US4283714A (en) * 1979-08-08 1981-08-11 Texas Instruments Incorporated Magnetic keyboard system
US4401986A (en) * 1979-12-26 1983-08-30 Texas Instruments Incorporated Position sensor and system
US5066951A (en) * 1988-10-28 1991-11-19 Mannesmann Kienzle Gmbh Circuit arrangement for adjusting the triggering point of an inductive keyboard

Also Published As

Publication number Publication date
FR2010089A1 (de) 1970-02-13
DE1928294B2 (de) 1971-06-24
GB1215114A (en) 1970-12-09
DE1928294A1 (de) 1970-02-19

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