US3683110A

US3683110A - Encoding device

Info

Publication number: US3683110A
Application number: US724767A
Authority: US
Inventors: Francis H Shepard Jr
Original assignee: Vogue Instrument Corp
Current assignee: Vogue Instrument Corp
Priority date: 1968-04-29
Filing date: 1968-04-29
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08
Also published as: FR2007210A1; CA926306A; GB1239158A; DE1921882A1

Abstract

An encoding device having a keyboard in which the depression of a key suddenly changes the amount of magnetic flux flowing through one of an array of magnetic core elements. Windings are arranged on each core element in a coded pattern, and the sudden flux change induces in the windings electrical output signals which are encoded in accordance with the coded arrangement of the windings. The depression of the key pulls a magnetic armature away from the upper magnetized stop member and towards the magnetic core element. The rapid movement of the armature which is provided by this ''''snap-action'''' assures that the rate of change of flux in the magnetic core will be sufficient to generate electrical output signals of a satisfactory magnitude. The upper stop member and its mounting structure provide a shunt path through which the magnetic flux in the armature by-passes the core when the key is in its rest position so as to minimize the flux flowing through the core until the key is depressed. A return spring and other means are described to return the armature to its original rest position after the key has been released by the operator.

Description

United States Patent [151 3,683,110 Shepard, Jr. 1 Aug. 8, 1972 [54] ENCODING DEVICE Primary Examiner-Kathleen H. Claffy 72 I t Francis R She ard Jn Assistant ExaminerThomas DAmico 1 men 0 Countryside, summit, Attorney-Curtis, Morris & Safford [73] Assignee: glrzlgigsiewlnlsfiument Corporation, 57 ABSTRACT An encoding device having a keyboard in which the Flledl p 29, 1968 depression of a key suddenly changes the amount of [21] APPL 724,767 magnetic flux flowing through one of an array of magnetic core elements. windings are arranged on each core element in a coded pattern, and the sudden flux [52] US. C1. ..178/17 C, 340/365 change induces in the windings electrical Output [51] Int. Cl. ..H04l 15/12 Signals which are encoded in accordance with the [C58] F'eld Search "179/90 178/] l 17 17 coded arrangement of the windings. The depression of i the key pulls a magnetic armature away from the 178/81; 340/365 197/98 8 3 51, upper magnetized stop member and towards the mag- 335/184 l netic core element. The rapid movement of the armature which is provided by this snap-action assures [56] References cued that the rate of change of flux in the magnetic core UNITED STATES PATENTS will be sufficient to generate electrical output signals of a satisfactory magnitude. The upper stop member 3,129,418 4/1964 DeLatour ..340/345 and its mounting Structure provide a Shunt path 3,119,99 1/ 1964 Comstock ..340/365 through which the magnetic fl i h armature 2,997,703 8/ 1961 Powell ..340/347 passes the core when the key is in its rest position so 2,814,031 ll /l957 Davis ..340/ 174 as to minimize the flux flowing through the core um 3,454,717 7/1969 PCICI'S ..178/17 the y i depressed A return spring and other means lg; --& are described to return the armature to its original rest emar position after the key has been released by the opera- 01.

35 Claims, 7 Drawing Figures P ATENTEBA E 8 I973 SHEET 3 0F 3 ATTORNEYS,

' ENCODING DEVICE The present invention relates to encoding devices, and particularly relates to devices for develop coded digital electrical signals representative of alphanumeric characters represented on a keyboard.

An illustrative use of an encoding device of the type to which the present invention relates is for producing binary-coded electrical signals in response to actuation of keys on a keyboard. The encoded electrical signals are sent to a utilization device such as a computer, a paper tape-punching mechanism, a magnetic recording device, a binary code actuated typewriter, or any other device which requires binary-coded input information.

One of the objects of the present invention is to provide a keyboard-type encoding device which is of relatively simple and inexpensive construction, has relatively few moving parts, and thus is less costly to build and more reliable in operation than prior encoding devices. This object is met, in accordance with the present invention, by the provision of a keyboard-type encoding device in which the actuation of each key suddenly changes the amount of magnetic flux flowing through one of an array of magnetic core elements. windings are arranged on eachcore element in a coded pattern, and the sudden flux change in the core develops electrical output signals in accordance with the coded arrangement of the windings. The actuation of each key moves a magnetic armature towards the core element and closes a magnetic circuit including the core element. The magnetic attraction of the core element for the armature accelerates the movement of the armature and ensures a high rate of change of flux in the core, and thus ensures that output signals of sufficient voltage will be developed in the windings. A magnet is used to hold the armature away from the core until the key is actuated. The resistance to movement of the key which the magnet creates makes it necessary to apply more force to the key to break it away from the magnet. This further increases the minimum velocity of the armature, and further increases the minimum output voltage produced by the windings. The holding magnet and its support structure provide a shunt path through which the magnetic flux in the armature by-passes the core when the key is in its rest position so as to minimize the flux flowing in the core until the key is actuated. A return spring or other means is used to return the armature to its original or rest position after the key has been released.

The invention now will be described with the assistance of the drawings in which:

FIG. 1 is a perspective, partially broken-away view of a preferred embodiment of the present invention;

FIGS. 2 and 3 are schematic diagrams illustrating operational features of the device shown in FIG. 1;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1;

FIG. 5 is a schematic, partially perspective view of a portion of the apparatus shown in FIG. 1;

FIG. 6 is a partially cross-sectional and partially broken-away view of another embodiment of the present invention; and I FIG. 7 is a partially perspective and partially schematic view of still another embodiment of the present invention.

The encoding unit indicated generally at 20 in FIG. 1 includes a housing 22, and a keyboard which is indicated generally at 24. The keyboard 24 includes an array of character keys such as 34, 36, 38 and 40, and

function keys

26, 28 and 30, all extending upwardly through holes in the top of the housing 22. The keys can be arranged in any pattern desired, but it is particu larly beneficial to arrange them in the pattern usually used in typewriters, Teletype keyboards and the like. By depressing the character and function keys of the keyboard, an operator can produce binary-coded electrical output signals which are delivered over an electrical cable 32 and are sent to a computer or other equipment which requires a binary-coded input.

Referring now to FIG. 4 as well as FIG. 1, each of the character and function keys includes a finger-receiving upper portion connected to a stem or plunger in the form of a plate. For example, the upper portions of

keys

34, 36, 38 and 40 are secured, respectively, to stems 35, 37, 39 and 41. Each of the stems is attached to a different one of a plurality of horizontally mounted elongated bars 92. Specifically, as is shown in FIG. 1,

I the stem 35 is secured to the bar 42; the stem 37 to the bar 44; the stem 35 to the bar 46; and the stem 41 to the bar 48 (see FIG. 1).

Each of the bars 92 has a slot in its left end which mates loosely with one of a plurality of notches 52 in an L-shaped pivot support member 50. The engagement between the bar 92 and the support 50 is loose so that each bar can be pivoted freely upwardly and downwardly and to each side.

Referring particularly to FIG. 4, the upper edge of an elongated leaf spring 54 fits into a notch 56 in each of the bars 92. The spring 54 thrusts the right end of each bar upwardly against a stop member 60 which is secured to a base plate 58. L-shaped coil support brackets 62 and 64 are secured, together with support member 50, to the base plate 58 by means of a bracket 59.

A coil 66 of wire is wrapped around the supports 62 and 64 so that the coil 66 encircles the rear portions of all of the bars 92. When the coil is electrically energized, it produces in each of the bars 92 a magnetic flux extending longitudinally through the bars. The bars 92, the support member 50, the base plate 58, the stop member 60, and the

key stems

35, 37, etc., are made of magnetic material of relatively high magnetic permeability but relatively low magnetic retentivity such as mild steel or soft iron. Thus, a plurality of complete magnetic paths is formed by each of the individual bars 92 together with the

members

50, 58 and 60. Flux developed by the coil 66 flows through this magnetic path and tends to hold each of the bars upwardly against the stop member 60 when the keys are in their uppermost or rest position.

Mounted on a base plate 68 of magnetic material are a plurality of

upstanding projection

70, 72, 74, 76, etc., each also being made of magnetic material. Each of the projections actually serves as a magnetic core element upon which one or more windings 69 of wire is wound. Each of the core elements is located directly beneath the lower end of the key stem of one of the keys on the keyboard. For example, the core70 is located directly beneath stem 35 of key 34; core 72 is beneath stem 37; core 74 is beneath stem 39; and core 76 is beneath stem 41. The cores thus serve as stops for the keys, as well as being magnetic core elements. The keys and the cores are located in four rows in which the keys in one row are staggered relative to the keys in the next row. With such an arrangement, only one of the parallel bars 92 is positioned directly over the center of a given core.

FIGS. 2 and 3 are schematic diagrams illustrating the operation of the encoder 20 shown in FIGS. 1 and 4. FIGS. 2 and 3 show the bar 44 and its associated components in two different operative positions. The

magnetic members

50, 58 and 60 are represented schematically by a single continuous magnetic member 78. The pivot point of the bar 44 is shown schematically at a point 80. The single coil 66 actually encircling all of the bars in the FIG. 1 structure is represented in FIGS. 2 and 3 by a separate coil wound upon the bar 44. A DC. power supply 86 is connected to the coil to energize it. The core 72 has two

windings

82 and 84 wound upon it. One end of each winding is grounded, and the other end provides an output signal when flux is developed in the core 72.

The magnetic circuits are indicated by the shading of the members, and the flux flow direction is shown by the arrows in FIGS. 2 and 3. When the bar 44 is in its upper or rest" position, as is shown in FIG. 2, a magnetic circuit which includes the bar 44 and the member 78 is completed. The core 72 and the bar 44 are separated by a substantial distance, and the path through the right-hand portions of the bar 44 and the member 78 is a low-reluctance shunt path around the core, so that very little flux flows through the core 72. The combined effect of the upward thrust of the spring 54 and the magnetic attraction between the upper right end of the member 78 and the right end of the bar 44 holds the bar in its uppermost position.

Now referring to FIG. 3, when the bar is pressed downwardly by the keyboard operator, the key does not start moving until the downward force reaches a value such that it overcomes the magnetic attraction between the member 78 and the bar 44. However, when the downward force reaches the break-away value, the bar 44 pulls away from the member 78 abruptly and moves downwardly at a high rate of acceleration. When the bar reaches a point located between the core 72 and the member 78, the magnetic flux starts passing in increasingly greater quantities through the core 72, and in correspondingly smaller quantities through the right end of member 78, and the magnetic attraction between the core 72 and the bar 44 increases very rapidly. The result is that the bar 44 comes into contact with the core 72 and a new magnetic circuit is formed through the left portion of the bar 44, through the core 72, and through the left portion of the member 78. Since the bar 44 has moved rapidly from the upper position to the lower position, the flux level in the core 72 has increased rapidly. This induces voltages in each of the

windings

82 and 84 wound about the core 72. Each of these voltage appears on an output lead which is transmitted through the cable 32 and provides a binary-coded signal, as will be described in greater detail hereinbelow.

One advantage of the present invention is that the downward movement of the bars 92 in response to the depression of the finger keys is quite rapid regardless of the rapidity with which the key is depressed. This effect is achieved by the use of the magnetic attraction between the bar 92 and the member 60 to latch the armature in its upper position. Thus, the keyboard operator must apply a certain minimum amount of force to each key before the bar moves. Then, because the magnetic attraction between the bar and the member 60 diminishes rapidly as the bar moves away from the member 60, and because a relatively large amount of force is applied to the key, the bar will snap or move rapidly downwardly to contact the core 72. This operation is highly desirable because it results in the maximization of the rate of change of flux in the core 72, and, hence, maximization of the amount of voltage developed by the

windings

82 and 84.

The rate of change of flux through the cores is further maximized by reducing the leakage or residual flux in each core to a very low level when its key is in its rest position so that the flux in the core must change by the greatest amount possible in order to reach the level provided by the coil 66. This is accomplished by making the contact 60 and the right-hand portion of base plate 58 a low-reluctance shunt around the core when the key is in its rest position.

Another advantage of the key actuation structure of the present invention is that when the operator has applied the required minimum amount of force to a key, the key snaps away from the contact 60 and hits the core member with a slight noise that can be heard and an impact that can be felt by the operator. Thus, the operator knows that the key has been struck properly.

Further advantages of the above-described structure are that it has no electrical contacts to get dirty, has no members which slide relative to one another, thus practically eliminating any problem of wear, and has a minimum of moving parts. It is extremely reliable, simple, and inexpensive to build.

The spring 54 is provided in order to return the bar 44 to its uppermost or rest position after it has made contact with the core 72 and has been released by the operator. It should be evident, therefore, that the restorative force, that is, the upward force exerted on the bar 92 by the spring 54 when the bar is in its lowermost position, must exceed the magnetic force of attraction between the core 72 and the bar.

It is desired that the spring 54 be relatively limber." A relatively stiff spring is not believed to be desirable since the amount of the restorative force it produces increases rapidly with increasing amounts of deflection. This is believed to be undesirable because, at various points of the movement of the bar 92, the restorative force provided by the spring might far overshadow the magnetic forces of attraction of either the core member or the stop member 60 so that the rapid snap-action" of the keys would not be obtained. Furthermore, use of such stiff springs might necessitate the use of excessive forces in pressing the finger keys. The spring 54 preferably is made of a non-magnetic material such as beryllium-copper so as not to provide an unwanted magnetic shunt path between the bar 92 and the plate 58, and is made of relatively thin stock (0.005 inch, for example) so as to be suitably limber.

It also is believed to be desirable to give the spring 54 a characteristic such that the restorative force it provides decreases as it is deflected by increasing distances. The leaf spring 54 can be given such a characteristic because the effective lever arm through which bending force is applied to it increases with increasing deflection.

The space bar 26 is a generally channel-shaped member (see FIG. 4) which is secured loosely to the stop member 60 by means of screws 91. A projection 93 is secured at a selected location along the length of the space bar 26. The projection 93 is positioned immediately above a selected one of the bars 92 so that depression of the space bar also depresses the selected bar 92 to develop the code designation for a space in the associated core windings.

Referring again to FIG. 1, a well-known ball-andtube device is provided to insure that only a single key may be depressed at a given instant of time. The balland-tube structure includes a tube 88 mounted beneath the right ends of the bars 92 by means of brackets 90 (see FIG. 4). The tube 88 is filled with a series of balls 94. A spring 96 and an adjustment screw 102 are provided at each end of the tube to spring-bias the balls toward one another, and to adjust the positions of the balls in the tube. The operation of this structure, which is well known, prevents more than one of the bars 92 from being pressed downwardly between two adjacent balls, and thus prevents thesimultaneous actuation of more than one key.

The components of the ball-and-tube structure preferably are made of a non-magnetic material such as brass so that the structure will not alter the magnetic flux paths through the bars 92 and other magnetic components, although they could be of magnetic material if they do not provide an appreciable magnetic shunting effect. For the same reason, it is preferred that the materials used in making the space bar 26 be of nonmagnetic material such as brass or plastic.

The coded pattern of winding of the magnetic cores may, be selected in accordance with the particular needs of a given use to which the decoder is to be put. Advantageously, the plate 68 upon which the core elements are mounted easily can be inserted into the encoding machine and removed from it in order to change the winding pattern on the cores, and thus change the code of the output signals produced by the encoder.

FIG. 5 illustrates a portion of the panel 68 upon which eight core members are mounted. Windings are shown on only six of the core members, those marked 1, 2, 3, 4, 5 and 6, in order to provide a simplified illustration for the purpose of explanation of the manner in which the cores may be wound. Assume, for the sake of this example, that it is desired to provide coded output signals representative of the decimal numbers 1, 2, 3, 4, 5 and 6, and that a binary code is to be used. In accordance with the well-known principles of binary mathematics, three different output signals are required to uniquely identify each of the six numerals in binary code. Assume further that each decimal number is to be represented by a binary number in accordance with the following table:

In the system of the present invention, the presence of an electrical signal represents a binary 1, and the absence of an electrical output signal represents a binary 0. Thus, in the present system, since a pulse is generated by the change of flux in the winding, the presence of a winding on a core represents a binary l,and the absence of a winding on a core in a location in which a winding might be located represents a binary 0. Referring again to FIG. 5, a first wire 106 is used to represent the right-hand column of binary numbers, a second wire 108 is used to represent the middle column, and a third wire 110 is used to represent the left-hand column of binary numbers. Thus, the wire 106 is looped once around the No. 1, No. 3 and No. 5 cores. Similarly, the wire 108 is looped once each around the No. 2, No.3 and No. 6 cores, and the wire 110 is looped once around each of the No. 4, No. 5 and No. 6 cores. One end of each of the

wires

106, 108 and 110 is grounded, and the other end is connected to the input of one of three

amplifiers

112, 113 and 115. The amplifiers amplify the signals developed in the core windings, and send them through

diodes

117, 119 and 121 to a unit 1 14 of equipment which utilizes the coded signals. The

diodes

117, 119 and 121 prevent the transmission of undesired negative pulses to the unit 114. Such undesired pulses will be created when the bars 92 snap back upwardly from their lowermost position to their uppermost position, thus developing in the coils 69 voltage pulses of reversed polarity from the voltages developed as the bars are snapped downwardly.

The unit 114, shown schematically in FIG. 5, can represent a tape-punch unit for punching the coded signals into a paper tape, or a magnetic tape recorder for recording the signals in magnetic form, or a computer which will use the signals to perform various functions, or a typewriter which requires a coded input, or any other type of equipment which requires a coded electrical input.

It is to be understood that the numbers of cores and windings used in the foregoing explanation and in FIG. 5 are merely exemplary. In a practical encoder device constructed in accordance with the present invention, there will be, for example, approximately 52 of the bars 92 and a corresponding number of cores, and there will be the usual number of character keys and various different function keys to operate the bars. A shift function key can be provided to add a code signal to the output to indicate whether the character being encoded is upper case or lower case; that is, in the case of alphabetic characters, whether the character is a capital letter or a small letter. Typically, if the code is binary, the shift function would be recorded as an additional bit in the code. The negative pulse generated in the core by the upward movement of a key can be used to generate a down-shift code signal after the shift key has been released. Alternatively, two separate shift keys can be provided, one to signal a shift to upper case, and the other to signal a shift to lower case. Various other function keys can be provided for encoding other function signals, as is well known in the art.

In an alternative embodiment of the invention, the coil 66 is eliminated, and each of the armature bars 92 is made a permanent magnet. Although the whole of each bar 92 can be permanently magnetized, it is preferred to make the bars 92 of a high-retentivity ferromagnetic material, and to heat-treat the portion of each bar which extends from the point at which the bar contacts its associated core to its right end, as seen in FIGS. 1 and 4, in order to give that portion of the bar a relatively low retentivity. Then the bar is placed in a strong magnetic field and the left end is permanently magnetized.

The bar 42 shown in FIGS. 1 and 4 can be considered to be a permanent magnet, formed in the manner described above, and consists of a permanently magnetized portion from its left end to just beyond the point of attachment of the stem 35 of the key 34 to the bar 42, and a portion to the right of the permanently magnetized portion which is not magnetized but conducts flux when the bar 42 contacts the member 60. When the bar 42 contacts the core 70, flux flows through the core and does not flow in any appreciable quantity through the right-hand portion of the bar. This embodiment of the invention has the advantage of reduced size and weight because the coil 66 has been eliminated.

FIG. 6 illustrates a portion of the keyboard of another alternative embodiment of the encoder of the present invention. The encoder shown in FIG. 6 is the same as that shown in FIG. 1 except that relatively limber springs 124 are fastened between the top portions of the keys and the armature bars 92. For example, springs 124 are shown in FIG. 6 connected between the top portions of the

keys

34 and 36 and the armature bars 42 and 44, respectively, in place of the upper portions of the key stems. Also, guide portions 126 are formed in the housing 22 to guide the keys and springs during their downward movement. It may be desirable to use the springs 124 in the manner described above in order to ensure that the armatures 92 snap downwardly with sufficient speed regardless of whether the operator moves his whole arm, only his wrist, or only his finger in depressing the keys. The spring is believed to store energy which is released when the armature 92 pulls loose from the contact 60 so that the armature moves downwardly rapidly regardless of the manner in which the operator depresses the keys.

FIG. 7 illustrates schematically an alternative arrangement for returning the bars 92 to their upper rest position after they have been depressed. Instead of the spring 54, a cylindrical rod 116 with a flattened surface is provided. The rod 116 is rotatably driven by a rotary solenoid 118. Whenever the solenoid 118 receives an input signal, it very rapidly turns the shaft 116 by about 30 to 40, and then returns it to its initial position. The flattened surface is at the top of the rod 116 when it comes to rest. Thus, when the bars 92 move downwardly, the bar 116 does not impede their downward movement. However, when the solenoid 118 rotates the rod 116, the edge of the rod cams the bars 92 upwardly to their rest position. The solenoid is operated, for example, by a signal received from an OR circuit device 120 over an electrical lead 122. The OR" circuit 120 has as many input leads as output leads for the encoder device, and its input leads are connected to the output terminals of the amplifiers connected to the windings. Whenever an electrical signal is developed on any of the output leads from the amplifiers, OR circuit develops a signal which causes the solenoid 118, after a slight delay, to rotate the rod 116 and return to its rest position any bar 92 which has been depressed.

The above description of the invention is intended to be illustrative and not limiting. Various changes or modifications in the embodiments described may occur to those skilled in the art and these can be made without departing from the spirit or scope of the invention as set forth in the claims.

I claim:

1. Encoding apparatus comprising a keyboard having a plurality of key members, a plurality of conductors, means for supporting said key members and conductors, flux means for supplying substantially steady and unidirectional magnetic flux means for converting a change in position of one of said key members into a change in the amount of said flux crossing at least one of said conductors and thus generating a voltage change in said one conductor, and output means for utilizing said voltage change as an output signal for said encoding apparatus.

2. Apparatus as in claim 1 in which said flux supplying means comprises at least one permanent magnet.

3. Apparatus as in claim 1 in which each of said keys is movable from a rest position to an actuated position, and including drive means for moving each key member to its actuated position after a minimum amount of force has been applied to said key member.

4. Apparatus as in claim 3 in which said drive means is magnetic.

5. Apparatus as in claim 1 includingfinger pieces, one for each key member, and resilient means coupling each finger piece to its key member. 7

6. Apparatus as in claim 3 including magnetic means for holding each of said key members in its rest position until a predetermined minimum level of force is applied to said key.

7. Apparatus as in claim 1 in which each of said key members is moved from a rest position to an actuated position and back again and two voltage changes are generated in said conductor, one during each movement of said key member, said output means being adapted to detect only one of said voltages.

8. Character encoding apparatus, said apparatus comprising, in combination, a keyboard including a plurality of keys, each of said keys having a rest position and an actuated position, a plurality of magnetic core elements, support means for supporting said core elements and said keys, a source of substantially steady and unidirectional magnetic flux, electrical conductors arranged adjacent said cores in a coded pattern, means for changing the amount of said magnetic flux flowing through one of said core elements in response to the movement of one of said keys from its rest position to its actuated position and thus generating coded voltages in the conductors adjacent said core, and means for detecting said voltages and utilizing them as the coded output signals of said encoding apparatus.

9. Apparatus as in claim 8 including a plurality of magnetic members, each movably mounted in said support means and connected to move with one of said keys towards one of said core elements, and moving means for moving each of said members towards its associated core element independently of any force applied to the key after a minimum amount of force has been applied to the key.

10. Apparatus as in claim 9 in which said moving means and said source comprise a permanent magnet providing magnetic attraction between each of said members and its associated core.

cm 11. An encoding device, said device comprising, in combination, a support structure, a plurality of keys movably mounted on said support structure, a plurality of magnetic core members windings on said core members, said windings being arranged onsaid core members in a digitally coded pattern, a plurality of elongated magnetic bars pivotably mounted in said structure, each of said keys being secured to one of said bars at a position spaced from the pivot point of said Mr whereby a force applied to-said key will cause said bar to pivot about said pivot point, each of said magnetic core members being mounted on said support structure at a location in the path of travel of one of said bars as it pivots, means for forming a magnetic flux path between each of said core members and the portion of each of said bars adjacent its pivot point, means for moving each of said bars away from each of said core members after the bar has been moved towards said core member, and means for applying a substantially continuous and steady magnetic flux to each of said bars.

12. Apparatus as in claim 11 in which the pivot point for each bar is located adjacent one end of the bar, and said moving means comprises a spring bearing upon the bar at a position adjacent its opposite end. i

13. Apparatus as in claim 11 in which said flux-applying means comprises a permanently magnetized portion in each of said bars.

14. In a character encoding device having a plurality of keys, electrical means for producing a coded electrical signal in response to the actuation of said keys, said electrical means includingvan armature made of magnetic material, said armature being movable into a first one of two different positions by the actuation of one of said keys to produce said coded electrical signals, first magnet means for attracting said armature to said first position, and second magnet means spaced from said first magnet means forattracting said armature to the other 'of said positions.

15. Apparatus as in claim 14 in which one of said magnet means includes a magnetic core located at one of said positions, with windings on said core for producing said coded signal, magnetic flux-developing means,

and means for forming a magnetic circuit including said core and said armature in series with said flux-developing means when said armature is in the position at which said core is located.

16. Apparatus as in claim 15 including means for biasing said armature towards said first position from said second position.

17. An encoding device, said device comprising, in combination, a plurality of keys, each having a quiescent condition and an actuated condition, a plurality of magnetic cores, means for supporting said keys and said cores, electrical windings wound on said cores in a coded pattern, means for developing magnetic flux, means for magnetically coupling said flux-developing means to a selected one of said cores in response to the l 0 actuation of a selected one of said keys, and means for de-coupling said core from said flux-developing means and for magnetically coupling a magnetic shunt to said flux-developing means to provide a magnetic flux path by-passing said core when said key is in its quiescent condition.

18. Apparatus as in claim 17 in which said keys are mounted in said supporting structure to be movable between an actuated and a quiescent position, said coupling means including a plurality of magnetic members, each being connected to one of said keys and being movable towards said core in response to actuation movement of the key to which it is connected and away from said core and towards said shunt upon return of said key to a quiescent position.

19. Apparatus as in claim 13 in which said decoupling means includes means for moving said magnetic member 'back towards said shunt and away from said core after coupling between said core and said flux-developing means has been effected.

20. Apparatus as in claim 19 in which said moving means comprises a spring urging said magnetic member towards said shunt with a restorative force greater than the force of magnetic attraction between said magnetic member and said core when said member is at its closest position to said core.

21. Apparatus as in claim 19 in which said moving means comprises a cam engaging said magnetic member, and means for driving said cam to move said member towards said shunt after an electrical signal has been developed in a winding on said core.

22. Apparatus as in claim'17 in which said fluxdeveloping means comprises a coil and electrical energization means for said coil.

23. Apparatus as in claim 17 in which said fluxdeveloping means comprises at least one permanent magnet.

24. Apparatus as in claim 18 in which each of said magnetic members is permanently magnetized, said magnetic members together comprising said fluxdeveloping means.

25. Apparatus as in claim 18 in which said magnetic members are pivotably mounted in said supporting means to swing into contact with said core and out of contact with said shunt, and then out of contact with said core and into contact with said shunt.

26. Character encoding apparatus, said apparatus comprising, in combination, a keyboard including a plurality of keys, each of said keys having an upper rest position and a lower actuated position, a plurality of magnetic core elements, support means for supporting saidcore elements and said keys with said keys in movable relationship to said core elements, means for changing the amount of magnetic flux flowing through one of said core elements in response to the movement of one of said keys from its rest position to its actuated position, electrical windings on said cores, said windings being wound on said cores in a predetermined binary-coded pattern, the electrical signals developed in said windings representing said characters in binarycoded form, said flux-changing means including a plurality of elongated bars made of magnetic material, magnetic flux-developing means, a magnetic shunt member, each of said bars being connected to one of said keys intermediate the ends of said bar, said bar being pivotably mounted at one end to pivot between an upper stop formed by said magnetic shunt member and a lower stop formed by one of said core elements, in response to upward and downward movement of one of said keys, a magnetic pivot support member pivotably supporting each of said bars at its pivot point, one end of each of said core elements and one end of said shunt being magnetically coupled to said pivot support, said bars being generally parallel to one another, and said cores being spaced apart with one core being located directly beneath each of said bars, and means for returning said bar to its upper stop after it has generated output signals in said windings by movement to said lower stop.

27. Apparatus as in claim 26 in which said fluxdeveloping means comprises a coil encircling the pivot end of each of said bars, and an electrical current source for said coil.

28. Apparatus as in claim 27 in which said fluxdeveloping source includes a permanently magnetized portion of each of said bars between its pivot point and the point of connection of the bar to its key.

29. Apparatus as in claim 26 in which said return means comprises an elongated, bent leaf spring engaging a notch in the bottoms of the bars near their ends opposite their pivot points, and anchored to a support surface below said bars.

30. Apparatus as in claim 26 in which said return means comprises a cam member rotatably mounted beneath the ends of said bars, a rotary solenoid connected in driving relationship to said cam member, and electrical means for energizing said solenoid when a signal is developed in one of said windings.

31. Apparatus as in claim 26 including a spring coupling each of said keys to its associated bar.

32. Apparatus as in claim 26 including a panel supporting said cores and windings, and means for removably supporting said panel in said encoding apparatus.

33. Character encoding apparatus, said apparatus comprising, in combination, a keyboard including a plurality of keys, each of said keys having a rest position and an actuated position, a plurality of magnetic core elements, support means for supporting said core elements and said keys, means for changing the amount of magnetic flux flowing through one of said core elements in response to the movement of one of said keys from its rest position to its actuated position, electrical windings on said cores, said windings being wound on said cores in a predetermined coded pattern, the electrical signals developed in said windings representing said characters in coded form, a plurality of magnetic members, each movably mounted in said support means and connected to move with one of said keys towards one of said core elements, and magnetic flux developing means for developing magnetic flux and causing it to flow through selected ones of said magnetic members and said core elements when said selected magnetic member and core element are brought together, and a further magnetized member for holding each of the first-named magnetic members in its rest position by means of magnetic attraction.

34. Apparatus as in claim 33 including a plurality of springs, each of said springs being connected between one f said ke s done of th first-named m ne ic mem rs, eac 0 said spring being posrtlonecfio be deflected by an actuating force on said keys prior to said member pulling away from said stop member.

35. Character encoding apparatus, said apparatus comprising, in combination, a keyboard including a plurality of keys, each of said keys having a rest position and an actuated position, a plurality of magnetic core elements, support means for supporting said core elements and said keys, means for changing the amount of magnetic flux flowing through one of said core elements in response to the movement of one of said keys from its rest position to its actuated position, electrical windings on said cores, said windings being wound on said cores in a predetermined coded pattern, the electrical signals developed in said windings representing said characters in coded form, at least one shift key, the movement of said shift key from its rest to its actuated position generating a shift signal in one of said core elements, and means for returning said shift key to its rest position from its actuated position after its release, said core generating a reverse shift signal in said core during its return movement.

Claims

4. Apparatus as in claim 3 in which said drive means is magnetic.

5. Apparatus as in claim 1 including finger pieces, one for each key member, and resilient means coupling each finger piece to its key member.

10. Apparatus as in claim 9 in which said moving means and said source comprise a permanent magnet providing magnetic attraction between each of said members and its associated core. cm 11. An encoding device, said device comprising, in combination, a support structure, a plurality of keys movably mounted on said support structure, a plurality of magnetic core members windings on said core members, said windings being arranged on said core members in a digitally coded pattern, a plurality of elongated magnetic bars pivotably mounted in said structure, each of said keys being secured to one of said bars at a position spaced from the pivot point of said bar whereby a force applied to said key will cause said bar to pivot about said pivot point, each of said magnetic core members being mounted on said support structure at a location in the path of travel of one of said bars as it pivots, means for forming a magnetic flux path between each of said core members and the portion of each of said bars adjacent its pivot point, means for moving each of said bars away from each of said core members after the bar has been moved towards said core member, and means for applying a substantially continuous and steady magnetic flux to each of said bars.

12. Apparatus as in claim 11 in which the pivot point for each bar is located adjacent one end of the bar, and said moving means comprises a spring bearing upon the bar at a position adjacent its opposite end.

14. In a character encoding device having a plurality of keys, electrical means for producing a coded electrical signal in response to the actuation of said keys, said electrical means including an armature made of magnetic material, said armature being movable into a first one of two different positions by the actuation of one of said keys to produce said coded electrical signals, first magnet means for attracting said armature to said first position, and second magnet means spaced from said first magnet means for attracting said armature to the other of said positions.

15. Apparatus as in claim 14 in which one of said magnet means includes a magnetic core located at one of said positions, with windings on said core for producing said coded signal, magnetic flux-developing means, and means for forming a magnetic circuit including said core and said armature in series with said flux-developing means when said armature is in the position at which said core is located.

17. An encoding device, said device comprising, in combination, a plurality of keys, each having a quiescent condition and an actuated condition, a plurality of magnetic cores, means for supporting said keys and said cores, electrical windings wound on said cores in a coded pattern, means for developing magnetic flux, means for magnetically coupling said flux-developing means to a selected one of said cores in response to the actuation of a selected one of said keYs, and means for de-coupling said core from said flux-developing means and for magnetically coupling a magnetic shunt to said flux-developing means to provide a magnetic flux path by-passing said core when said key is in its quiescent condition.

19. Apparatus as in claim 13 in which said de-coupling means includes means for moving said magnetic member back towards said shunt and away from said core after coupling between said core and said flux-developing means has been effected.

22. Apparatus as in claim 17 in which said flux-developing means comprises a coil and electrical energization means for said coil.

23. Apparatus as in claim 17 in which said flux-developing means comprises at least one permanent magnet.

24. Apparatus as in claim 18 in which each of said magnetic members is permanently magnetized, said magnetic members together comprising said flux-developing means.

26. Character encoding apparatus, said apparatus comprising, in combination, a keyboard including a plurality of keys, each of said keys having an upper rest position and a lower actuated position, a plurality of magnetic core elements, support means for supporting said core elements and said keys with said keys in movable relationship to said core elements, means for changing the amount of magnetic flux flowing through one of said core elements in response to the movement of one of said keys from its rest position to its actuated position, electrical windings on said cores, said windings being wound on said cores in a predetermined binary-coded pattern, the electrical signals developed in said windings representing said characters in binary-coded form, said flux-changing means including a plurality of elongated bars made of magnetic material, magnetic flux-developing means, a magnetic shunt member, each of said bars being connected to one of said keys intermediate the ends of said bar, said bar being pivotably mounted at one end to pivot between an upper stop formed by said magnetic shunt member and a lower stop formed by one of said core elements, in response to upward and downward movement of one of said keys, a magnetic pivot support member pivotably supporting each of said bars at its pivot point, one end of each of said core elements and one end of said shunt being magnetically coupled to said pivot support, said bars being generally parallel to one another, and said cores being spaced apart with one core being located directly beneath each of said bars, and means for returning said bar to its upper stop after it has generated output signals in said windings by movement to said lower stop.

27. Apparatus as in claim 26 in which said flux-developing means comprises a coil encircling the pivot end of each of said bars, and an electrical current souRce for said coil.

28. Apparatus as in claim 27 in which said flux-developing source includes a permanently magnetized portion of each of said bars between its pivot point and the point of connection of the bar to its key.

34. Apparatus as in claim 33 including a plurality of springs, each of said springs being connected between one of said keys and one of the first-named magnetic members, each of said spring being positioned to be deflected by an actuating force on said keys prior to said member pulling away from said stop member.