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Publication numberUS3707611 A
Publication typeGrant
Publication dateDec 26, 1972
Filing dateSep 29, 1970
Priority dateOct 15, 1969
Also published asDE2050784A1
Publication numberUS 3707611 A, US 3707611A, US-A-3707611, US3707611 A, US3707611A
InventorsTwyford Robert H
Original AssigneeMechanical Enterprises Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Coding keyboard and electrical switch therefor
US 3707611 A
Abstract
A keyboard for electronic apparatus such as computer and communication equipment, and an electrical switch therefor including a resilient deformable tube filled with an electrically conductive liquid such as mercury. Included in the keyboard is an elongated conductive means comprising a plurality of side-by-side conductors. The keyboard switch modules are each provided with a plurality of contact elements and mounting means adapted for holding the contact elements in anyone of a plurality of predetermined positions whereby each switch module can be encoded and thus preconditioned for electrically energizing a different preselected combination of the conductors to represent the desired code data unique to each switch.
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Description  (OCR text may contain errors)

United States Patent Twyford 1 Dec. 26, 1972 541 CODING KEYBOARD AND 3,494,550 2/1970 Hayes et al ..200/159B ELECTRICAL SWITCH THEREFOR 22 1;; l----- /152.9 3,360,6 Nic e son ZOO/152.9 Wanton W Falls Church 3,536,932 10/1970 Humbert-Droz ..307/106 [73] Assignee: Mechanical Enterprises lncor- Primary f' Hohauscl' pol-ted Attorney-Birch, Swindler, McKie & Beckett [21] P'' 76496 A keyboard for electronic apparatus such as computer n ted A union and communication equipment, and an electrical e a pp switch therefor including 'a resilient deformable tube C0"lifluaiion-in-lli"t 0f S66Y488- 15, filled with an electrically conductive liquid such as 1969- mercury. included in the keyboard is an elongated conductive means comprising a plurality of side-by- [52] U.S.Cl. ..200/211,200/l88, 200/5 E, Side conductors. The keyboard switch modules are gg g g each provided with a plurality of contact elements and [51] i 2 B E mounting means adapted for holding the contact ele- [58] held M 87 88 3 ments in anyone of a plurality of predetermined posil tions whereby each switch module can be encoded and thus preconditioned for electrically energizing a [56] References cued different preselected combination of the conductors to UNITED-STATES PATENTS represent the desired code data unique to each switch.

3,591,749 7/1971 Comstock .,200/159 B 28 Claims, 11 Drawing Figures PATENTED DEC 2 6 m2 SHEET 1 BF 4 m mm E WH m PATENTEDBEBZB m2 3,707.61 1

saw 2 [1F 4 INVENTOR ROBERT H TWYFORD PATENTED E I972 3.707.611

sum 3 or 4 Q PATENTEUnEc 26 m2 SHEET [If 4 FIG. 8

CODING KEYBOARD AND ELECTRICAL SWITCH THEREFOR PRIOR APPLICATION This is a continuation in part of application Ser. No. 866,488, filed Oct. '1 5, 1969.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of electric switch keyboards, such as find extensive use in the computer and related industries. Further the invention is concerned with electrical switches and encoded switch modules particularly adapted for arrangement and use in such keyboards.

2. Description of the Prior Art The computer and related data processing industries offer many applications for keyboards. The cost of such keyboards has become a significant factor with the large volume requirements for keyboards in remote terminals, input devices and other peripheral equipment used in computer and data processing applications.

A variety of electrical switch designs for such keyboards, to generate the requisite coded signals, have been proposed. These have ranged from mechanical electrical switch concepts through electronic switching proposals. In all such designs, low initial investment and maintenance free operation with high operational reliability are prime requisites. A particular requirement for a satisfactory keyboard switch is one wherein closure of the electrical circuit occurs with a bounce free response. Such bounce free circuit closing is characterized by creation of a clean electrical signal wherein a non-erratic rise from one voltage level to another occurs when the switch is closed by depression of the key on the keyboard connected to actuate the switch.

In electric switch keyboards, coded electrical signals must be transmitted rapidly with precise accuracy in sending data from say a remote terminal to a computer location. This requires a bounce free switch closure for operation of the various solid state circuits most frequently involved in utilization of the coded data. Upon depression of a key on the keyboard and consequent closure of the switch operated by the key, a clean shift from one voltage condition to another, with a clean change in the voltage level must occur.

The inability to obtain the perfection required in keyboard switches has necessitated utilization of additional components in the form of bounce gates or delay circuits so that the undesired, unclean or fluttering closure of the electrical circuit is blanked out to be prevented from interfering with proper operation of the solid state circuits controlled by the coded electrical signal data. Of course, the necessity for adding bounce gates and delay circuits, broughtabout by the inability to achieve a bounce free switch response, adds to the cost of'the keyboard and related equipment.

In seeking to achieve the ideal of a bounce free" keyboard. switch, the prior art has shied away from metalto metal contact switches, which are quite prone to produce an unclean fluttering or bouncing closure of an electrical circuit. In doing this various, highly refined and elaborate electronic switching proposals have been developed and incorporated in keyboard construction. These approaches can be expensive and complex in their solutions to the problem of generating clean, coded, electrical signal data and frequently, lack the flexibility for make up of a keyboard which will meet the wide variety of applications in the computer and data handling fields.

SUMMARY OF THE INVENTION It is a principal object of the invention to provide a miniaturized manually actuatable electrical switch particularly capable of being utilized in electrically coded data transposing equipment, such as keyboards used in the computer and data processing fields.

An adjunct and further primary aim of the invention is to provide a switch module, for keyboard applications mentioned in the above object, capableof being readily and easily preconditioned or encoded so as to be able, upon closure, to produce and transmit particular coded electrical signals in the form of data unique to the encoding of the switch.

Another very important object of the invention is to provide an electrical switch capable of producing a bounce free" electrical signal wherein a clean, non-erratic change from one voltage level to another characterizes the signal generated upon switch closure.

The invention also has as its object to provide a key operated switch possessing the advantages of the above recited object wherein switch actuation is accompanied by improved touch or feel in depressing and releasing the switch key while long switch life is achieved.

A further important object of the invention is to provide an electrical switch module for use in keyboard applications wherein each switch for the keyboard is completely encoded, independently of other keyboard switches, and the individual switches are capable of being employed at a multitude of different keyboard'locations and not limited to use at a single keyboard location.

A further object is to provide a switch module, adapted for the above mentioned keyboard applications, wherein such module embodies solid state encoding with only one switch contact circuit being opened and closed in actuation of the switch for each module.

It is also an object of the instant invention to provide a switch module particularly suited for electronic keyboard equipment wherein the encoding for the switch to represent desired unique code data can be readily changed as may be desired without the necessity of interrupting semipermanent junctures such as soldered connections.

A further object of the invention is to provide an electric switch keyboard wherein reduced cost is achieved as by avoiding use of frequently used printed circuit boards and wherein the keyboard is characterized by complete versatility to enable making up different keyboards with many different key locations to meet the variety of needs for keyboards in the computer and data processing fields.

The foregoing objects, aims and purposes of the invention are substantially met and the shortcomings of the prior art are substantially alleviated through the use of. the present invention which in one aspect includes a switch comprising an elongated, deformable, resilient tube; an electrically conductive liquid substantially filling said tube; and an actuator including a tube contacting edge portion operable to laterally displace at least a central segment of the tube sufficiently far to crimp said segment of the tube across said portion whereby to pinch the liquid and open an electrical circuit. Thus is provided an efficient, inexpensive, normally electrically open switch having extremely simple mechanical construction.

In another aspect, the invention includes an encoded push button switch module adapted for transmitting a preselected coded combination of electrical signals to an electrically conductive means comprising a plurality of elongated side-by-side electrical conductors. In this aspect of the invention the switch comprises a pair of electrical contacts and a switching mechanism including a manually operated actuator operable to make and break and electrical circuit between the contacts. Also included are a number of elongated contact elements and a contact element mounting member having a plurality of elongated contact element receiving openings extending therethrough. The openings are relatively disposed for simultaneous alignment with corresponding conductors. Contact elements are disposed in only certain of the openings corresponding to the desired preselected encoding combination required to represent the code data unique to each switch. Also included is an electrically conductive member mounted on the mounting member. The conductive member is provided with a plurality of resilient extensions, a respective one of which projects across one end of each of the openings in disposition for yieldably contacting, in electrical current transmitting relationship, the proximal end of a contact element in the opening. Thus, the contact element is yieldably urged in the direction of its opposite end and into electrical current transmitting relationship relative to a corresponding conductor. One of the contacts of the switching mechanism is disposed in electrical current transmitting relationship relative to the conductive member while the other contact of the switching mechanism is disposed for contacting one of the conductors in current transmitting relationship therewith. Thus is provided a unitary encoded switch module which can be readily incorporated onto an electronic keyboard.

In yet another aspect, the invention includes an electrical keyboard which includes a frame; an elongated electrical conducting means including a plurality of elongated, generally parallel, laterally spaced conductors, said conducting means being mounted on the frame; and at least one push-button switch mounted on the frame adjacent the conducting means, said switch including an electrical contact, at least one electrical contact element, means for yieldably biasing the contact element toward a corresponding one of the conductors and into electrical current transmitting connection therewith, and a switching mechanism operable to make and break an electrical circuit between said contact and said contact element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially exploded perspective view of an electronic keyboard which embodies the concepts and principles of the instant invention;

FIG. 2 is an exploded perspective view of an electric switch which embodies the concepts and principles of the invention, certain portions of the switch housing having been cutaway to expose internal details;

FIG. 3 is a perspective view of the contact element mounting member of the switch having the electrically conductive element biasing structure mounted thereon;

FIG. 4 is an enlarged cross-sectional view of the switch of FIG. 2 in its normal, electrically open condition;

FIG. 5 is a cross-sectional view of the switch in its actuated, electrically closed condition;

FIG. 6 is a cross-sectional view taken substantially along line 6-6 of FIG. 4;

FIG. 7 is a cross-sectional view taken substantially along line 7-7 of FIG. 5;

FIG. 8 is a cross-sectional view taken substantially along line 8-8 of FIG. 4;

FIG. 9 is a partial cross-sectional view embodiment;

FIG. 10 is an exploded perspective view of the upper end of the switch housing illustrating the alternate embodiment of FIG. 9; and

FIG. 11 is a partial cross-sectional view similar to FIG. 4 but showing an alternate improved switch embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT I An electrical device in the nature of a keyboard for an electronic computer or thelike is illustrated in FIG. 1 and is broadly designated by the numeral 20. Keyboard 20, which embodies the principles and concepts of the invention, includes a frame 22 and a plurality of push-button switches 24. Incidentally, FIG. 1 is a partially exploded view of a keyboard which would have 10 switches 24 such as utilized in the keyboard of a ten key adding machine or calculator. However, it is to be understood that the board could have any desired number of switches as may be required.

Each of the switches 24 for keyboard 20 includes a housing 26 having a cavity 28 extending therethrough. Housing 26, including its mounting base 30, is preferably formed in one piece from a moldable, thermoplastic resin, such as for example, polycarbonate resin or the like. It is to be appreciated, however, that the material of construction of housing 26 is not critical and other suitable materials are well-known to the routineer in this art.

Cavity 28 is defined within housing 26 by opposed side walls 32, opposed end walls 34 and a lower wall 36. Opposed grooves 38 formed in end walls 34 are aligned with a slot 40 in lower wall 36. A shoulder 25 is provided on the underside of base 30. Shoulder 2S completely surrounds slot 40 and extends in parallelism therewith from one side of base 30 to the other. Thus is presented a pair of spaced indentations 27 disposed in opposed relationship on opposite sides of shoulder 25.

An actuator 42 is received within cavity 28 with its opposed sides 44 slideably disposed within grooves 38, the latter thereby establishing a path through cavity 28 upon which actuator 42 is reciprocable. Actuator 42 has an elongated slot 43 therein adapted for alignment with a pair of holes 45 in housing 26. A pin 47 extends through holes 45 and slot 43 to limit the extent of reciprocable movement of actuator 42.

A tube 46 constructed of deformable and resilient material, such as rubber, plastic, or some other like elastomer, is positioned to extend through cavity 28.

of an alternate Preferably, tube 46 will be disposed in a U-shaped configuration with the central segment 48 and the bight 50 thereof extending upwardly through slot 40 into cavity 28. Tube 46 will generally be substantially filled with an electrically conductive, non-wetting liquid, such as, for example, mercury. One end of tube 46 is closed with a contact 52 while the other end of the tube is closed with a contact 54, contacts 52 and 54 being disposed in contacting relationship relative to the liquid within tube 46.

A sleeve 56 is secured onto each end of tube 46 adjacent contacts 52 and 54 respectively. Sleeves 56 are slightly larger in diameter than the width of slot 40 for a purpose to be explained hereinbelow. When tube 46 and actuator 42 are disposed within cavity 28, the bight 50 of tube 46 is disposed around a tube contacting edge portion in the nature of a knife edge 58 formed on actuator 42. In this regard, bight 50 extends between knife edge 58 and a second; more rounded tube contacting portion 60 also formed on actuator 42.

An upper extension 62 on actuator 42 projects externally of housing 26 and mounts thereon a manually engageable element in the nature of an indicia displaying push button 64. A coil spring 66 is disposed between the upper surface 68 of base 30 and push button 64 for yieldably biasing push button 64 away from mounting base 30. Thus, actuator 42 is urged upwardly along its path of reciprocation which extends through cavity 28 and generally laterally to one side of tube 46. Accordingly, actuator 42 is yieldably biased into its tube crimping position illustrated in FIGS. 4 and 8. In this position, segment 48 of tube 46 has been displaced sufficiently far that the same is crimped and pinched as it is stretched over knife edge 58 whereby the liquid in tube 46 is parted. It should be noted that tube 46 is stretched across edge 58 because sleeves 56 are larger in diameter than slot 40 and therefore the ends of tube 46 are held against upward movement. Whereas edge 58 is shown as having a relatively sharp configuration it will be appreciated that this edge may be blunted or more rounded to. achieve some increase in the life of tube 46.'I-Iowever, with a sharp edge 58 the switch is less sensitive to accidental closing of the circuit.

In operation, spring 66 biases actuator 42 into its tube crimping position illustrated in FIGS. 4 and 8. In this position, tube 46 is crimped across knife edge 58 and is pinched to part the liquid therein. Accordingly, switch 24 is normally disposed in an electrically open condition. When push button 64 is manually forced downwardly against the bias of spring 66, knife edge 58 is moved downwardly until tube 46 is released whereby switch 24 assumes its tube releasing position illustrated in FIGS. 5 and 9. In this latter position, the resilience of tube 46 will cause central segment 48 and bight 50 thereof to assume their normal cylindrical shape whereby the liquid in the tube will become joined so that an electrical current can be transmitted between contacts 52 and 54.

As push button 64 is actuated, and as knife edge 58 moves downwardly, the upper tube contacting portion 60 of actuator 42 will contact the crimped portion at the bight 50 of tube 56 to thereby assist in removing the crimp created when knife edge 58 was in its upper position. This action provides an extremely'quick response.

Mounting base 30 is provided with four support legs 70. Legs 70 are cantilevered downwardly from the corners of base 30 and each has asmall protrusion 72 thereon for a purpose to be described below.

A contact element mounting member in the nature of a block 74 is provided for supporting a plurality of elongated contact elements 76 and 78. Block 74 may preferably be constructed of the same material as housing 26 and is provided with a plurality of contact element receiving openings which extend therethrough. Viewing FIG. 8, it can be seen that each opening 80 is provided with a shoulder 82 at the lower end thereof for supporting elements 76 and 78 during assembly. Thus, each opening 80 has a lower portion 81 of reduced size surrounded by shoulder 82.

Switches 24 are particularly adapted for use with an electrical conducting means 84 comprising a backing strip 86 and a plurality of elongated, generally parallel, side-by-side conductors 88. For "this purpose, the openings 80 through block 74 are disposed in substantially parallel relationship for simultaneous alignment with corresponding of the conductors 88. That is to say, when block 74 is disposed in its operational relationship relative to conducting means 84, a respective conductor 88 is disposed directly in line with and beneath each opening 80.

The switches 24 most generally will be used with direct current. Thus, elements 76 and 78 preferably comprise diodes to prevent reverse flow of current when various combinations of the conductors are connected by closing a switch 24. In this regard, element 78 preferably includes a resistor 78a as well as a diode 78b for a purpose to be described below. In any event, elements 76 and 78 are slightly longer than the openings 80. Further, each includes a lower extension 90 which is longer than portions 81 of holes 80 and which is disposed to project outwardly of block 74 when elements 76 and 78 are disposed within openings 80. Elements 76 and 78 each also have an upper extension 92 disposed to project outwardly of openings 80 at the opposite end thereof from lower extension 90.

An electrically conductive structure in the nature of a current distributor 94 is mounted on body 74. Distributor 94 may preferably be formed from a copperberyllium alloy and includes a generally U-shaped central strap 96 having a short leg 98, a long leg 100, and a bight 102 interconnecting legs 98 and 100. Distributor 94 also includes a plurality of resilient extensions 104 which project laterally outwardly from leg 100. An alignment hole 106 is provided in leg for impalement on a corresponding alignment peg 108 on block 74. Distributor 94 is also provided with a hole 110 in leg 98 adapted for alignment with a threaded hole 112 in block 74. Thus, distributor 94 may be securely held in place on block 74 by a screw 114 received through hole 110 and threadably engaged within threaded hole 112. Manifestly, other means for attaching distributor 94 to block 74 will be apparent to those skilled in the art.

, When distributor 94 is properly in place on block 74 with peg 108 projecting through hole 106 and with screw 114 extending through hole 110 and into hole 112, a respective resilient extension 104 projects across the upper end of each opening 80. Extensions 104 are disposed for yieldably contacting, in electrical current transmitting relationship, the upper extension 92 of a contact element 76 or 78 disposed within a corresponding opening 80. Accordingly, since elements 76 and 78 are longer than openings 80, and since lower extensions 90 are longer than reduced portions 81 of openings 80, extension 104 urge elements 76 and 78 in the direction of their lower extension 90. Hence, when block 74 is disposed in operational relationship relative to conducting means 84, contact elements 76 and 78 will be yieldably biased toward corresponding conductors 88.

An elongated opening 116 in leg 100 of distributor 94 is disposed to expose a pair of side-by-side openings 118 and 120 which extend through block 74 in general parallelism with openings 80. Block 74 also has a pair of openings 122 extending therethrough for alignment with corresponding threaded openings 124 in mounting base 30. Accordingly, block 74 is attached to the underside of base 30 by a pair of screws 126 which extend through openings 122 and into openings 124. It is to be noted that shoulder 25 bears directly on leg 100 of distributor 94 and indentations 27 provide space for proper functioning of extensions 104. In this connection, an alignment hole 127 is provided in shoulder 25 in position to receive alignment peg 108 therein.

When block 74 is mounted on the underside of base 30, openings 118 and 120 are in alignment with slot 40. Further, openings 118 and 120 are sized to receive sleeves 56 of tube 46 therein. Also, it is to be noted that leg 98 of distributor 94 is disposed directly beneath opening 118. Contact 52 is received within opening 118, and contact 52 and its corresponding sleeve 56 are slightly longer than opening 118 so that contact 52 will press against leg 98 in electrical current transmitting relationship thereto. In this connection, as is best illustrated in FIG. 4, leg 98 is yieldably forced downwardly by contact 52 whereby a positive pressure is maintained between leg 98 and contact 52.

Contact 54 and its corresponding sleeve 56 are disposed within opening 120. Opening 120, like openings 80, is disposed for alignment with one of the conductors 88a adapted for serving as a common conductor to provide simultaneously a source of electrical current for a plurality of switches 24. Manifestly, contact 54 and .its corresponding sleeve 56 must be sufficiently long to connect with conductor 88a in electrical current transmitting relationship thereto.

Elements 76 and 78 are preferably disposed in only I certain preselected openings 80 corresponding to a predetermined coded combination electrical signal which represents the desired code data unique to each switch. For example, with openings 80 as illustrated, switch 24 is capable of transmitting 2,048 different binary encoded characters represented by electrical signals. In this regard, it is to be recognized that the signal may be established by energizing any combination of one or more of the conductors 88. Manifestly, extensions 92 of contact elements 76 and 78 are all contacted by distributor 94 and therefore the elements 76 and 78 are all connected in parallel electrical relationship.

As discussed above, a plurality of switches 24 are mounted on frame 22 to present keyboard 20. Frame 22 has a stair-step configuration providing a plurality of steps 128 separated by risers 130. Steps 128 are separated by walls 132 extending upwardly from corresponding risers 130. Also, a similar wall 134 is provided on the outboard side of the uppermost step 128 while a wall 135 is provided on the outboard side of the lowermost step 128. A groove 136 extends longitudinally of wall 134 and of each riser 130. A corresponding groove 138 extends longitudinally of wall 135 and of each wall 132. Grooves 136 are thus disposed in opposed, generally parallel relation relative to corresponding grooves 138 on opposite sides of each step 128.

Conducting means 84 may preferably be in the form of an elongated tape provided with an adhesive, such as a pressure sensitive backing, on the opposite side of backing 86 from conductors 88. Thus, tape 84 may be installed to extend along one step 128, back along the next higher step 128, etc., as best illustrated in FIG. 1. At the end of each step the tape 84 is folded through two successive 45 bends to continue back along the next higher step. In this connection it is to be noted that the relative positions ofconductors 88 are reversed on adjacent steps 128. That is to say, the conductor 88 which is closest to wall 132 on the lowermost step 128, will also be closest to the same wall 132 as tape 84 extends in the opposite direction along the next higher step 128. Since the relative positions of the conductors 88 are reversed on adjacent steps 128 of frame 22, the disposition ofswitches 24 must also be reversed so that the elements 76 and 78 remain in proper disposition relative to conductors 88. After, conducting means 84 is installed, lengths of insulating tape 133 may be provided to cover the bent over ends 135 of the conducting means 84.

Grooves 136 and 138 are disposed for snappingly receiving therein protrusions 72 of legs on each switch 24. In this regard, legs 70 are sufficiently resilient so that switches 24 may be readily snapped into place between the opposed facing surfaces of opposed walls 132.

Contact element 78 composed of a combination of resistor 78a and diode 78b is adapted for serving a special purpose. This type element will preferably be disposed in the same opening in each block 74'for switches 24. That is to say, element 78 will be disposed in the upper left hand opening 80a (See FIG. 2) of each of the switches. 24 of the keyboard 20. Openings 80a are disposed in alignment with a conductor 88b which will therefore serve as a common conductor for all of the elements 78. Hence, if two or more switches 24 are actuated simultaneously, the electrical current characteristics in conductor 88b will be different than when only a single switch 24 is actuated and this difference can be detected and used to reject such signals representing the improper actuation of more than one switch 24 at any one time.

Switches 24 may each be provided with an overcenter device adapted to give the operator of keyboard 20 a better feel in depressing each switch. This device gives a sensation of a snap action when each switch is depressed. This device, which preferably takes the form of a transversely bowed cricket spring 140 (FIGS. 9 and 10), is adapted for causing the resistance acting against push button 64 during operation of switch 24 to change at the moment that the crimp in tube 46 is released to open an electrical circuit. Spring 140 is preferably mounted on a peg 141 to extend across the upper end of cavity 28 and through slot 43 of actuator element 42. As push button 64 is depressed, the upper end 43a of slot 43 contacts spring 140 and therefore spring 140 yieldably resists the movement of actuator 42 as the latter moves downwardly. The bow transversely of the length of spring 140 initially resists downward movement of actuator 42 with a stronger force than such spring offers when the bowed form snaps flat as actuator is pressed further down. Spring 140 should preferably be positioned relative to end 430 such that spring 140 will pass its central or snap" point and collapse at approximately the same time that the crimp in the tube 46 is released. Thus, the change in resistance to movement of push button 64 will inform an operator that the coded signal unique to the actuated switch has been transmitted.

Referring to FIG. 11, this partial cross-sectional view illustrates an improved switch embodiment incorporating many of the features characteristic of the switches heretofore described while embodying an actuator having a perfected tube contacting edge portion for crimping the mercury filled resilient tube. This switch embodiment also incorporatesstructure to better contain and utilize the biasing force of the spring which normally retains the switch in its open circuit condition.

As in the previously described switches 24, useable with keyboard 20, the switch embodiment shown in FIG. 11 includes a housing 26 provided with a cavity 28. The cavity 28 is defined by opposed side walls, opposed end walls and a lower wall with opposed grooves 38 formed in the end walls of the cavity similar to the construction of the previously described switch embodiments. An actuator 42 is slideably disposed within grooves 38 to be reciprocable therein. A deformable resilient tube 46 filled with an electrically conductive, non-wetting liquid such as mercury is mounted in a U- shaped configuration with a central segment 48 and the bight 50 thereof extending upwardly into the cavity 28, all as characteristic of the switches previously described.

The actuator 42 is provided with an upper extension 62 and an indicia displaying key or push button 64 is frictionally pressed onto the upper extension 62 of actuator 42 to provide the manually engageable element utilizedfor actuation of the switch. A'coil spring 66 also is provided encircling the exterior of the wall defining cavity 28, this spring being compressed, as in the previous switch embodiments, to urge the push button 64 away from housing 26 for the switch to assume its normal electrically open circuit condition.

A disc 150 having'a cup-like cross section, as shown on FIG. 11, is disposed between the upper end of coil spring 66 and the bottom of push button 64. Disc 150 has a central slot 152 formed therein through which the upper extension 62 on actuator 42 passes. Preferably, the slot 152 is of a size that the disc 150 frictionally engages with the extension 62 so that the disc is retained on the upper end of actuator 42. The cup-like configuration of disc 150 engages over the upper end of coil spring 66 to guide and retain the upper end of spring Byutilization of disc 150 holding spring 66 through frictional engagement of slot 152 with extension 62, the switch is kept in fully assembled condition, with or without the presence of a key or push button 64 pressed onto the uppermost end of extension 62 above disc 150. Thus, a selected push button, displaying the desired identifying indicia for the particular switch, may be placed on the switch extension 62 or removed as desired, and different push buttons interchanged, without freeing the coil spring 66. Spring 66 is at all times retained in place and the switch thereby held in its normal open circuit condition by the presence of cup-like disc frictionally secured on extension 62 to retain the coil spring.

The actuator 42 in the embidiment of FIG. 11 has an elongated slot 154 extending longitudinally thereof. A hollow pin 155 extends transversely part way across cavity 28 with one end of the pin being retained in one of the opposed side walls of the cavity 28 in housing 26. This pin 155 passes partially into slot 154 from one side and acts to limit the extent of reciprocable movement of actuator 42. However, for reasons which will be apparent pin 155 is short enough that an open passageway remains extending down from slot 154 through the lower end of actuator 42. As shown in FIG. 11, the coil spring 66, acting through cup-like disc 150, while pressing against housing 26 urges actuator 42 to its uppermost limit where pin 155 is in engagement with the lowermost end of slot 154.

Of particular importance in the switch embodiment of FIG. 11 is the perfected tube contacting edge portion on actuator 42 which acts against the central segment 48 and bight 50 thereof of tube 46 so that the tube is crimped and pinched as it is stretched over the edge portion whereby the liquid in tube 56 is parted and consequently the switch normally exists in a circuit open condition. This edge portion of actuator 42 in FIG. 11 is provided by the lower end of a coil spring 156. The upper end of spring 156 is provided with a loop which is engaged in a hole 158 formed in the upper end of the actuator body immediately below the upper extension 62 of the actuator.

The coil spring 156 extends downwardly through the open passageway extending down from slot 154 past the end of pin 155 and is provided at its lower end with a hook 160. This hook provides the tube contacting edge portion for the switch actuator 42, the hook being engaged with the central segment 48 and bight 50 thereof of deformable tube 46.

Thus, when the'switch assumes its normal open circuit condition, as shown in FIG. 11, the coil spring 156 is tensioned by the actuator body being in its uppermost position under the biasing action of external coil spring 66. This urges hook 160 on coil spring 156 upwardly so that the segment 48 of tube 46 is displaced sufficiently far that the same is crimped and pinched as it is stretched over the hook 160 whereby the liquid in tube 46 is parted and the switch exists in an open circuit condition.

In the switch design of FIG. 11, it has been found that provision of the tube contacting edge portion on the switch actuator 42 by utilizing the hook 160 on the end of a coil spring 156 provides a better touch or feel in operation of the switch. This aspect is of particular importance in utilization of switches of this construction in keyboards where switch actuations are achieved by manual depression of selected keys or push buttons assembled in groups on the keyboard. Actually, a lesser spring force can be employed in the switch embodiment of FIG. 11 and still achieve the necessary pinching of the liquid filled tube in accomplishing a circuit open condition. In this respect it will be appreciated that the tension of exterior spring 66 tends to be reduced or offset by tension of internal spring 156 engaged with segment 48 of tube 46 tending to pull the actuator body and push button 64 down. Also of advantage in the FIG. 11 type switch construction, has been the determination that a thinner tube wall thickness for tube 46 can be employed adjacent the point on the tube where it contacts the edge portion formed by hook 160. This thinning of the tube can be undertaken without encountering any loss of life in the tube resulting from repeated opening and closing of the switch Thus, the desired sensitivity in switch operation and requisite bounce free opening and closing of an electrical circuit can be achieved where the tube 46 has the central segment 48 ground down over a limited area to thin the wall thickness of the tube where the edge portion provided by hook 160 engages the tube to pinch it in obtaining circuit opening. Accordingly, this switch construction, embodying the spring type tube pinching actuator, has particular advantages rendering the switch most ideally suited for coded keyboard applications, such as the keyboard construction heretofore described.

It can readily be seen that the switch of the instant invention and a keyboard comprising a plurality of the same, substantially solves many of the problems inherent in prior art devices. The switch includes an extremely uncomplicated switch mechanism capable of crimping a mercury filled tube in an efficient manner with a minimum of moving parts. Further, each switch is capable of being encoded or preconditioned to transmit anyone of a large plurality of predetermined electrical code signals representing informative data. Hence, the switches may be combined with a conductor tape to present a keyboard which has outstanding constructional features including simplicity of assembly.

' It is to be understood that the form and'embodiment of the invention, herein shown and described, are to be taken only as preferred representations of the invention and that various changes and modifications in the arrangement of the components, parts, units, etc. may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

Iclaim:

1. In a switch,

an elongated, deformable, resilient tube;

' an electrically conductive liquid substantially filling said tube; and

an actuator including a tube contacting edge portion,

said actuator being mounted relative to said tube to laterally displace at least a central segmental length of the tube to crimp said segmental length of the tube across said edge portion whereby to part the liquid in said tube and open an electrical circuit intermediate the ends of said tube.

2. In a switch as set forth in claim 1, said edge portion including a knife edge disposed to extend transversely of said tube. I

3. In a switch as set forth in claim 1, said edge portion being provided by a spring member having an end engaged with said central segmental length of said tube.

4. In a switch as set forth in claim 1, said actuator being reciprocable in a direction laterally of said tube between tube crimping and tube releasing positions.

5. In a switch as set forth in claim 4, there being included a spring operably coupled to said actuator for yieldably biasing the latter toward its tube crimping position.

6. In a switch as set forth in claim 4, said actuator including a spring member having an end providing said tube contacting edge portion, said end being engaged with said central segment of said tube and said spring member being reciprocable as a part of said actuator.

7. In a switch as set forth in claim 4, there being biasing means provided to urge said actuator toward its tube crimping position, said actuator including a manually engageable element operable for manually forcing said actuator toward its tube releasing position.

8. A switch comprising:

a housing having a cavity therein;

an elongated, deformable, resilient tube extending through said cavity, the ends of said tube being supported against movement by said housing; an electrically conductive liquid substantially filling said tube; and v an actuator supported by the housing for reciprocation along a path extending through the cavity adjacent the tube, said actuator including a tube contacting edge portion disposed for contacting and laterally displacing at least a central segmental length of the tube within said cavity when said actuator moves in one direction along said path, said actuator being movable in said one direction to crimp said length of said tube across said edge portion whereby to part the liquid in said tube and open an electrical circuit intermediate the ends of said tube.

9. A switch as set forth in claim 8 wherein biasing means is included to yieldably urge said actuator in said.

one direction along said path.

10. A switch as set forth in claim 8 wherein said actuator includes a manually engageable element extending externally of said housing, said element being operable for manually forcing said actuator in the opposite direction along said path, there being included an over-center device which normally yieldably resists movement of said actuator in said opposite direction.

11. A switch as set forth in claim 10 wherein said device comprises a cricket spring extending across said path.

12. A switch as set forth in claim 8 wherein said edge portion includes a knife edge disposed to extend transversely of said tube.

13. A switch as set forth in claim 8 wherein said edge portion is defined by a spring member having an end engaged with said central segmental length of said tube.

14. A switch as set forth in claim 8 wherein is included a pair of contacts, each contact being disposed in closing relationship to a respective end of the tube and in contacting relationship relative to the liquid therein, said tube being disposed in a generally U- shaped configuration with. the contacts extending outwardly of the housing and generally. in the same direction, said edge portion being disposed for contacting the tube at the bight of the U-shaped configuration.

ing:

a number of elongated contact elements;

a contact element mounting member mounted on the housing adjacent said contacts and having a plurality of elongated contact element receiving openings extending therethrough in the same direction as said contacts, said openings being relatively disposed for simultaneous individual alignment with a corresponding plurality of con-' ductors of an electrical conducting means which means comprises a plurality of elongated, side-byside conductors;

said contact elements being disposed in preselected of said openings representing a predetermined coded combination electronic signal; and v an electrically conductive structure mounted on said contact element mounting member and having a plurality of resilient extensions, said extensions each overlying one end of one of said contact element receiving openings, said extensions each being disposed for yieldably contacting, in electrical current transmitting relationship, the proximal end of a contact element in the opening which it overlies whereby to yieldably urge the element toward the opposite end of each opening, said conductive structure being disposed in electrical current transmitting relationship relative to one of said contacts, the other contact being disposed for contacting one of the conductors of said conducting means.

16. In an electrical switch keyboard device,

aframe;

an elongated electrical conducting means fixedly mounted on the frame including a plurality of generally parallel, laterally spaced conductors supported by said frame against displacement; and

at least one push-button switch mounted on the frame adjacent the conducting means and said switch including an electrical contact and at least one electrical contact element, means for yieldably biasing the contact element toward a corresponding conductor and into electrical current transmitting connection therewith, and. a switching mechanism operable to make and break an electrical circuit between said contact and said element.

17. In an electrical switch keyboard device as set forth in claim 16 said device including a plurality of said switches, each switch having its contact element located for connection with a different conductor.

18. In an electrical switch keyboard'device as set forth in claim 17, each of said switches having its contact disposed in electrical connection with a common conductor adapted for providing electrical current to all of the switches simultaneously, one of the elements of each switch being disposed in electrical connection with another common conductor whereby to facilitate detection of a condition when more than one switch is actuated simultaneously,

1 9. In an electrical switch keyboard device as set forth in claim 16 wherein said switch has at least two contact elements, said elements being electrically con 20. In an electrical switch keyboard device as set forth in claim 16 said switch including a contact element mounting member having a plurality of elongated contact element receiving openings extending therethrough, said mounting member beingdisposed with its openings each aligned with one of said conductors, each of said contact elements being elongated and extending through a corresponding opening.

21. In an electrical switch keyboard device as set forth in claim 20 said means for yieldably biasing the elements toward the conductors comprising an electrically conductive member having a plurality of resilient extensions, there being a resilient extension overlying the end of each opening remote from said conducting means, said extensions each being disposed for yieldably contacting the proximal end portion of a contact element in the corresponding opening and urging the element through its opening and toward a corresponding conductor.

22. In an electricalswitch keyboard device as set forth in claim 20, said member having an opening for each conductor, there being a contact element in only certain of said openings representing a preselected combination of conductors whereby said switch is preconditioned upon actuation to transmit a preselected coded combination electrical signal.

23. A push button switch adapted for transmitting a preselected coded combination of electrical impulses to an electrical conducting means having a plurality of elongated, side-by-side electrical conductors, said switch comprising:

a pair of electrical contacts;

a switching mechanism operableto make and break an electrical circuit between the contacts including a manually'operated actuator element;

a number of elongated contact elements;

a contact element mounting member having a plurality of elongated contact element receiving openings extending therethrough, said openings being relatively disposed for simultaneous individual alignment with respective corresponding conductors, said contact elements being disposed in only certain of said openings corresponding to a preselected coded combination electrical signal; and

an electrically conductive member mounted on said mounting member and having a plurality of resilient extensions, there being a resilient extension overlying one end of each of said openings disposed for yieldably contacting, in electrical current transmitting relationship, the proximal end of a contact element in the corresponding opening whereby to yieldably urge the element in the direction of its opposite end and into electrical transmitting relationship with a corresponding conductor,

said conductive member being disposed in electrical current transmitting relationship relative to one of the contacts of the mechanism,

the other contact of the mechanism being disposed for contacting one of said conductors in current conducting relationship therewith.

24. A switch as set forth in claim 23 wherein said contact elements comprise diodes.

25. A switch as set forth in claim 23 wherein said mechanism includes an elongated, deformable, resilient tube and an electrically conductive liquid substantially filling said tube, said contacts being disposed in tube closing and liquid contacting relationship at opposite ends of the tube, said actuator element including a tube contacting edge portion, said actuator element being mounted relative to said tube to laterally displace at least a central segmental length of the tube to crimp said segmental length of the tube across said edge portion whereby to part the liquid and open an electrical circuit intermediate the ends of said tube.

26. In a switch, an elongated, deformable, resilient tube; an electrically conductive liquid substantially filling such tube; an actuator including a tube contacting edge portion, said actuator being mounted to reciprocate in a direction laterally of said tube between tube crimping and tube releasing positions by displacing at least a central segment of the tube and crimping said segment across said edge portion whereby to part the liquid in said tube and open an electrical circuit intermediate the ends of said tube; a coil spring urging said actuator toward its tube crimping position; I a push button separable from said actuator and manually operable to force said actuator toward its tube releasing position; and a disc member frictionally retained on said actuator beneath said push button to transmit biasing force of said coil spring to said actuator. 27. In a switch, an elongated, deformable, resilient tube, an electrically conductive liquid substantially filling such tube; and

an actuator including a tube contacting edge portion, and a second tube contacting portion disposed on the opposite side of the tube from said edge portion, said actuator being mounted relative to said tube to reciprocate in a direction laterally of said tube between tube crimping and tube releasing positions by displacing at least a central segment of the tube and crimping said segment across said edge portion whereby to part the liquid in said tube and open an electrical circuit intermediate the ends of said tube, said second tube contacting portion having engagement with the tube proximal the crimp therein to assist in straightening the crimp in the tube as the actuator moves toward its tube releasing position.

28. A switch comprising:

a housing having a cavity therein; 7

an elongated, deformable; resilient tube extendin through said cavity, the ends of said tube being supported against movement by said housing;

an electrically conductive liquid substantially filling said tube; and

an actuator supported by the housing for reciprocation along a path extending through the cavity adjacent to the tube, said actuator including a coil spring having one end thereof connected to and reciprocable as a part of said actuator and the other end provided with hook means engaged with at least a central segmentof said tube within said cavity for laterally isp acmg said central segment when said actuator moves in one direction along said path, said actuator being movable in said one direction to crimp said segment of said tube across said hook means of said coil spring to part the liquid in said tube and open an electrical circuit intermediate the ends of said tube.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3809838 *Nov 1, 1971May 7, 1974Bunker RamoModular push button switch assembly mounted on printed circuit board
US3903389 *Feb 11, 1974Sep 2, 1975Faustini CarloSelf-encoding key switch and keyboard system utilizing the same
US4124313 *Mar 21, 1977Nov 7, 1978Kienzle Apparate GmbhKeyboard assembly
US4202640 *Apr 27, 1978May 13, 1980Kienzle Apparate GmbhKeyboard assembly
US4331851 *Jun 16, 1980May 25, 1982Texas Instruments IncorporatedPrinted circuit board having data input devices mounted thereon and input devices therefor
US4684275 *Jun 24, 1983Aug 4, 1987Tokyo Electric Co., Ltd.Electronic typewriter with presettable specification tables
US6965511 *Oct 10, 2001Nov 15, 2005Hewlett-Packard Development Company, L.P.System and method for personalizing an electrical device
US7005588Jun 10, 2004Feb 28, 2006Nokia CorporationKeyboard and a method for manufacturing it
US7157651 *Mar 19, 2004Jan 2, 2007Ergodex, Inc.Independently positionable and programmable key switches
US20040256203 *Jun 10, 2004Dec 23, 2004Pekka PihlajaKeyboard and a method for manufacturing it
US20050000787 *Mar 19, 2004Jan 6, 2005Rix Scott M.Independently positionable and programmable key switches
US20050141190 *Feb 11, 2005Jun 30, 2005Rudd Michael L.System and method for personalizing an electrical device
US20070108034 *Dec 28, 2006May 17, 2007Ergodex, Inc.Independently positionable and programmable key switches
Classifications
U.S. Classification200/211, 400/472, 200/345, 200/188, 200/5.00R, 200/5.00E
International ClassificationH04L13/16, H01H29/00, H04L13/00, H01H13/70
Cooperative ClassificationH04L13/16, H01H13/70, H01H29/004
European ClassificationH01H13/70, H04L13/16, H01H29/00C