US3671700A

US3671700A - Momentary multiple contact switch and operating key therefor

Info

Publication number: US3671700A
Application number: US82029A
Authority: US
Inventors: Jack L Metz
Original assignee: Teletype Corp
Current assignee: AT&T Teletype Corp
Priority date: 1970-10-19
Filing date: 1970-10-19
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20

Abstract

The contact assemblies of a pile-up are separated each from an adjoining thereof by a thin spacer with an opening through which a flexible contact portion of one assembly is projectable into engagement with a like portion of an adjoining assembly. A key operated impactor is arranged adjacent one end of the pile-up in alignment with the flexible portions and becomes tensioned upon key operation. Tensioning force of the impactor is released during key operation through the agency of a cam which overcomes the impactor tensioning means for driving the impactor into impacting engagement with the flexible portion of the proximate contact assembly. In consequence of the impacting force, the contact portions of the assemblies successively are driven into engagement and develop a condition of simultaneous momentary engagement to close a circuit, the input to which is through the contact assembly on the end of the pile-up distal to the impactor.

Description

United States Patent 1 June 20, 1972 Metz [54] MOMENTARY MULTIPLE CONTACT SWITCH AND OPERATING KEY THEREFOR [72] inventor: Jack L. Metz, Des Plaines, 111. [73] Assignee: Teletype Corporation, Skokie, Del.

22 Filed: on. 19, 1970 211 App1.No.: 82,029

[52] [1.8. CI. ..200/160, 200/77, 200/166] [51] Int. Cl. l-l0lh 13/50 [58] Field of Search ..200/ 160, 77, 74, 76, 159 A, 200/166 811, 166.1, 159 R, 78, 153 W [56] References Cited UNITED STATES PATENTS 3,073,935 l/1963 Smusz ..200/160 3,163,738 12/1964 Farrell 200/166] 3,557,332 1/1971 Femandes ..200/160 2,671,140 3/1954 Schellman ..200/77 FOREIGN PATENTS OR APPLICATIONS 546,001 3/1956 Belgium ..,...2o0/16o 1,260,591 -2/1968 Germany.... ..200/160 962,745 7/ 1964 Great Britain ..200/153 OTHER PUBLlCATlONS IBM Technical Disclosure, Vol. 13, No. 8, pp. 2419, 2420; Actuator For Elastic Diaphragm Switch" by Harris et al.; Jan. 1971 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Attorney-J. L. Landis and R. P. Miller [57] ABSTRACT The contact assemblies of a pile-up are separated each from an adjoining thereof by a thin spacer with an opening through which a flexible contact portion of one assembly is projectable into engagement with a like portion of an adjoining assembly. A key operated impactor is arranged adjacent one end of the pile-up in alignment with the flexible portions and becomes tensioned upon key operation. Tensioning force of the impactor is released during key operation through the agency of a cam which overcomes the impactor tensioning means for driving the impactor into impacting engagement with the flexible portion of the proximate contact assembly. In consequence of the impacting force, the contact portions of the assemblies successively are driven into engagement and develop a condition of simultaneous momentary engagement to close a circuit, the input to which is through the contact assembly on the end of the pile-up distal to the impactor.

12 Claims, 10 Drawing Figures 56 FIG.

Patenmd Jum 2Q, 19%

2 Sheets-Sheet 1 FBG. 5

CHARACTER GENERATOR INVENTOR JACK L. ME

ATTORNEY MOMENTARY MULTIPLE CONTACT SWITCH AND OPERATING KEY THEREFOR BACKGROUND OF THE INVENTION The present invention relates to a multiple contact switch and an operating key assembly therefor. Particularly it relates to an input key assembly of the type comprising a keyboard and in response to which a distinctive encoded electrical output is produced.

In conventional communications equipment, each of selected keys in a keyboard is depressably mounted for producing a plural level encoded electrical output characteristic of a symbol to be reproduced. The electrical contacts associated with each key are arranged for closure simultaneously but independently each from the others thereof to produce each characteristic output. In consequence, if any electrical contact, which is associated with a selected key, fails to close, a false output is generated, resulting from closure of the remainder of the contacts.

It is an object of the present invention to prevent the aforesaid shortcoming.

It is another object of the invention to provide a novel plural contact switch.

It is a further object of the invention to provide an improved key assembly adapted simultaneously to close a plurality of contacts of a plural contact switch.

It is an additional object of the invention to prevent an electrical effect from a switch having more than two electrical contacts unless all of the electrical contacts are closed.

SUMMARY OF THE INVENTION To effect the foregoing, and other objects of the invention which will become apparent from ensuing description, a switch assembly comprises a pile-up of aligned conductive bodies. The latter are held in an electrical discontinuity by a plurality of aligned insulators arranged between the bodies and proportioned such that upon application of a pressure of predetermined magnitude to the bodies, all of the bodies are driven into electrical contact. To that end, each insulator has an opening and an insulative fabric which is continuous about its opening. Electrical contact of a pair of bodies adjoining an insulator is effected through the opening of the insulator disposed between such adjoining bodies.

From another aspect, the foregoing objects of the invention are achieved by an electrical switch comprised of a plurality of bodies having flexible conductive portions disposed in a stack. The bodies have a normal position in which their conductive portions are spaced apart each from an adjoining thereof. An

impactor is arranged adjacent the flexible conductive portion 7 of a body at one end of the stack. The impactor has a first condition in which the contacts are disposed in their normal condition and a second condition in which the said flexible conductive portions are engaged. Key responsive means arearranged for driving said impactor between said second and first conditions. Also means are provided for tensioning said impactor while it is in its first condition; and means are provided for releasing the tension and driving said impactor into its second condition.

Considered from yet another aspect, the objects of the invention are achieved with a key assembly of the type which has an impactor reciprocatively arranged within a housing for producing an effect in response to release of spring tension resulting from depression of a self restorable depressible cap. Tension release means comprises a cam for removing an impactor restraint which prevents tension release during a part of a cap depressing stroke as spring tension is generated for biasing the impactor toward an effect-producing aspect. Thehousing has a wall with an aperture and defines a chamber; and the cam is fixed relative to the housing. The impactor has a body arranged for movement in the chamber upon release of spring tension and a projection disposed in the aperture, the projection being extendable from said aperture for producing said effect. Means having a part associated with the housing limit cap movement relative to the housing following cap release from depression.

BRIEF DESCRIPTION OF THE DRAWINGS In the ensuing detailed description of the invention reference is had to the accompanying drawings in which:

FIG. 1 is a sectional view of one embodiment of the invention;

FIG. 2 is a view according to line 2-2 in FIG. 1, a part having been omitted for clarity;

FIG. 3 is an exploded perspective view of said embodiment;

FIG. 4 is an exploded perspective view of a pile-up comprisingsaid embodiment;

FIG. 5 is an electrical scheme of said pile-up;

FIG. 6 is a sectional view of a modified embodiment of said invention;

FIG. 7 is a view according to the line 7-7 in FIG. 6;

FIG. 8 is a view according to line 8-8 in FIG. 6, a part having been omitted for clarity;

FIG. 9 is a view according to line 9-9 in FIG. 7; and

FIG. 10 is an exploded view in perspective of a pile-up having contact assemblies modified from the contact assemblies shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment Referring now more particularly to FIGS. 1-4, shown is a key assembly generally designated 11 and comprised of a cylinder or elongated cylindrical housing 12 and a depressible, self restorable cap 14. The keyassembly is of a type which is of a type which is adapted to operate a switch assembly 16 through an agency of an impactor generally designated 18 for producing an output effect in response to movement of the cap.

The longintudinal axis of housing 12 is adapted for vertical disposition and thereby the housing may be vertically oriented as shown. The housing has a lower opening 20 (FIG. 1) and an upper wall or roof 22. The roof has an inner or lower surface 24 (FIG. 1) and an outer or upper surface 26. A chamber 28 within the housing communicates with the exterior thereof through an aperture 30 which extends vertically through the roof and is concentric with the axis of the housing.

An elongated slot 32 formed through the cylindrical side wall 34 of housing 12 along substantially its entire length, also connects chamber 28 to the exterior thereof. The slot has a substantially rectangular upper section 36 which terminates short of roof 22, and a lower narrower substantially rectangular section 38 which opens through the base of wall 34.

The housing may be suitably retained on a horizontal insulative base or support 40 (FIG, I) by suitable fastening means herein shown as terminal caps 42.

Tension releasing means (the significance of which will become apparent from ensuing description) herein includes a cam comprised of a pair of sloping shoulders 44 and 46 (FIG. 3). They are fashioned in wall 34 of housing 12 on opposite sides of the slot 32 and are generated at the juncture of its upper and

lower sections

36 and 38. The shoulders are disposed in a common plane, sloping through wall 34 downwardly from chamber 28 as they slope outwardly.

Impactor 18 has a stepped cylindrical configuration (FIG. 3) defining a body 48 which is proportioned for vertical reciprocation in chamber 28 and a smaller upper projection 50 which is proportioned for reciprocation in aperture 30. A flat surface 52 is generated at the upper end of body 48. A compressible damper 54 which may be annular is connected to surface 24 about aperture 30 and limits upward movement of the impactor in chamber 28. A compression spring 56 comprises means for driving the impactor. It is disposed in a lower part of chamber 2' and bears against the lower surface of body 48 and base 40 whereby the impactor is urged toward said damper.

Each spring 56 and impactor 18 has a normal, passive or untensioned condition (FIG. 1) in which the upper surface of projection 50 coincides with the plane in which outer surface 26 of roof 22 is disposed. Additionally, the impactor has two other positions (not shown), namely (1) a tensioned position to which it moves downwardly from the position of FIG. 1, as a result of depression of cap 14 to compress spring 56, and (2) an active position which results from the release of tension following spring compression and in which projection 50 extends upwardly beyond surface 26 to produce a switching effect in a manner which hereinafter will become apparent.

To tension or compress spring 56, cap 14 may be adapted for manual operation by providing an upper component 58 carried integrally from the upper end of a shell 60 which defines the lower end portion of said cap. The shell is arranged for vertical reciprocation about the exterior of housing 12 and is depressible against the restoring action of a compression spring 62 (FIG. 1). The latter member bears against the inner surface of the upper end wall 64 of the shell and a retainer or spacer 66 which is supported within a chamber 68 in the upper end of said shell. The retainer is superposed from surface 26 and provides a compartment 70 in the lower end of chamber 68 and above surface 26 of roof 22.

Shell 60 is shown as rectangular in cross section and has a vertical window or opening 72 (FIG. 3) through which chamber 68 communicates to the exterior. A vertically elongated arm 74 comprising flexible latching means is hangingly disposed in said window and has an upper end portion 76 which is flexibly connected from the shell. The connection is such that said arm can be bent outwardly from its normal position (FIG. 3). The lower end portion of arm 74 carries a latch 78 which comprises means for tensioning impactor 18. The latch is proportioned for projection and projects into slot section 36. However, the latch is wider than slot section 38, and, in consequence, it cannot be accommodated therein.

By reason of the foregoing construction, key assembly 11 operates as follows: Upon depression of cap 14 from its normal position (FIG. 1), latch 78 engages a catch 80. The catch is carried from body 48 of impactor 18 at its outer end portion, and is disposed in the upper section 36 of slot 32 when the impactor is in its normal position. The width of the catch is such that it can be reciprocatively accommodated in slot section 38 as well as in slot section 36. The parts are proportioned such that, as the impactor is moved downwardly from its normal position, the entire catch will be driven by the latch into slot section 38. However, because of its width, catch 78 will engage and be bent by the sloping

shoulders

44 and 46, relative to which said catch is a follower, outwardly until corner 82 of the latch clears corner 84 of the catch. Thereupon, there being no restraint on the impactor, it will be driven upwardly against damper 54 as spring 56 decompresses. The parts are proportioned such that the force resulting from spring decompression is sufficient to momentarily drive the upper end of projection 50 above the upper surface 26 and produce an effect in switch assembly 16. The damper limits the breach of said last surface to prevent more than one closure following spring decompression.

To limit upward movement of cap 14 upon its restoration resulting from untension or decompression of spring 62 after cap release following cap depression, a boss or dog 85 (herein shown as a screw) is secured from a portion of the shell 60 for catching against roof 22 of the housing 12.

Exemplary switch assembly 16 (FIGS. 4 and is a pile-up, that is, a stack of electrically

conductive bodies

86, 87, 88, 89. They are vertically arranged and nonnally vertically spaced apart to effect electrical discontinuity therebetween. An insulator 90 is disposed between adjoining conductive bodies for effecting their spacing. An insulator 91 is disposed between the lowermost body 86 and the upper surface 26 of roof 22 against which said pile-up is urged and securely retained by compression spring 62. To thAt end, retainer 66 may be fabricated of an insulative material and has a depending centering boss 92 (FIG. 4) which engages uppermost insulator 94 from within and from above urging the latter downwardly into engagement with the uppermost conductive body 89.

In the embodiment of FIG. 4, conductive bodies 86-89 are generally circular configurations having the same diameters.

Insulators

90, 91 and 94 are annular and have substantially the same diameters as the conductive bodies. Accordingly, switch assembly 16 has a generally cylindrical configuration. Each of the insulators has an opening 96 bounded by an insulative fabric which is continuous about such opening.

Each of the conductive bodies 86-89 has an inwardly extending conductive portion or contact 98 which is flexible. Each contact is aligned with the contact of an adjoining body for engagement therewith through an opening 96 which is disposed between the adjoining contacts. The parts are proportioned such that upon release of impactor tension following cap depression, projection 50 will be driven from its tensioned condition, in which the contacts are spaced apart, through opening 96 of the lowermost insulator 91, a distance sufficient to cause contact 98 of conductive body 86 to bend. The distance of the bending is sufficient to produce a series of flexions of successively higher contacts 98 such that all of the contacts simultaneously will be in engagement momentarily to produce thereamong electrical continuity before the impactor is restored to its normal condition.

Each of the conductive bodies 86-89 has a radially extending terminal 100 (FIG. 4) which is anchored about and in engagement with a respective of a plurality of

vertical leads

103, 104, and 106. The latter are elongated conductors which are spaced angularly about and extend longitudinally of housing 12. The upper end portions of the leads are mounted in retainer 66 from which said leads depend normally in angularly spaced channels 102 (FIG. 3) in wall 34 of housing 12. The lower end portions of said leads extend below wall 34 and may be anchored in base 40 for electrical connection by any suitable means herein being heretofore defined terminal caps 42 (FIG. 1).

Means comprising a circuit generally designated 111 (FIG. 5) are adapted to produce an output which is characteristic of an associated key assembly 11 only when all of the contacts are closed. To that end, a logic circuit, such as a conventional character generator 112, is adapted to produce an output effect which corresponds to an associated key assembly. Neither the details of construction of the character generator nor its connection means (not shown) to utilizing apparatus is intended to be limiting on the present invention.

To actuate the character generator in the exemplary apparatus, a common end of each of leads 103, 104, and 105 is connected by an associated of

conductors

108, 109 and 110 (FIGS. 1 and 5) to character generator 112, to provide inputs thereto. At their opposite ends the

leads

103, 104, and 105 are connected through respective associated

resistances

115, 116, and 117 to a plane of reference herein shown as ground 114.

At one end, lead 106 is connected by a conductor 118 to one side of a power source for direct current herein shown as battery 119, the opposite side of said battery being connected to ground 114. Accordingly, power from the battery cannot pass to the character generator 112 until conductive body 88 has engaged conductive body 89; and such engagement cannot be achieved until each lower conductive body has in its turn been engaged from below and bent into engagement above, as aforesaid. Thereby, no output signal will be generated should any contact fail to close following untensioning of impactor 18. The lead 108, connected to the lowermost conductive body 86 is a universal or starting contact which initiates operation of the character generator. Thus, unless all conductive bodies (86-89) in the stack are electrically connected, the character generator cannot operate. The intermediate leads 109-110 (and other similar leads which would be connected to additional intermediate conductive bodies for a more complex code) are data contacts connected within the character generator in a distinct pattern for each key to produce a unique output for each key in known fashion.

Alternate Embodiments An alternate switch assembly 120 (FIG. corresponds to switch assembly 16 but has modified

conductive bodies

122, 123, 124, and 125. In the alternate assembly, the conductive bodies are substantially solid and are proportioned and constructed such that medial contact portions 126 thereof will flex in response to the driving force of an associated impactor. Thereby, electrical engagement will be effected through openings 127 in the insulators 128 which keep said bodies normally spaced apart and in electrical discontinuity, each from the other. Alternate switch assembly 120 as well as switch assembly 16 may be used with the modified embodiment of the invention (FIGS. 6-9) comprised of a key assembly 130.

Assembly 130 also may be vertically disposed such that its cylinder or housing 132 projects upwardly from a base 133. When thusly arranged, the direction of switch impaction is downwardly. To that end, the housing has a lower wall 134 with a central aperture 136 therethrough. Said last wall limits from below a chamber 138 in which an impactor 140 is arranged for vertical reciprocation.

An impacting projection 142 from impactor 140 is operatively disposed in aperture 136. A damper 144, which corresponds to damper 54, is disposed between the inner surface of wall 134 and impactor 140 about aperture 136. At its lower end portion, the housing 132 forms a compartment 146 of which wall 134 is a roof and base 133 is a floor. The compartment is adapted for accommodating switch assembly 120.

Impactor tensioning means comprises a compression spring 148 (FIG. 6) disposed in chamber 138 above impactor 140. It has an upper end bearing against the inner surface of roof 150 of housing 132 to urge impactor 140 to its normal condition. A catch 152 which projects from impactor 140 is proportioned for vertical movement in a slot 154 in the side wall 155 of housing 132.

A cap 156 includes a shell 157 which is disposed about housing 132. It is biased to a normal or restored position by a compression spring 158 which is arranged within the shell and bears against the upper surface of roof 150 and the inner surface of said cap. To limit upward movement of the cap upon untensioning of spring 158 a boss or dog 160 is arranged in vertical slot 161 through the shell for engagement with a housing flange 162.

Tensioning means for impactor 140 also comprises a latching structure 164 fashioned as a bail with a lower transversely extending latch 165 adapted to engage catch 152 from below for tensioning the impactor. To that end an arm 166, comprising lifting or elevating means, has an end portion 168. A medial part of an upper transverse segment 170 of the latching structure is pivotably and liftably connected in end portion 168. A medial part of arm 166 is rigidly secured to a pivot pin 172 which extends transversely of said arm parallel to the latch and segment 170. The pivot pin is supported through an upper end portion of chamber 138 by a pair of opposed recesses 174 (FIG. 8) fashioned in the upper end portion of housing 132 in which the opposite end portions of said pivot pin engage. An opposed end portion 176 of arm 166 has a normal condition when cap 156 is normally extended. In the normal condition end portion 176 is aligned with a superposed striker 178 which is rigidly secured from cap 156 and extends into shell 157.

By reason of the foregoing construction, as cap 156 is depressed from its normal condition, striker 178 will rock am 166 counterclockwise relative FIG. 6 until said striker loses control of said arm by passing beneath end portion 176. Simultaneously, latch 165 is elevated and moves impactor 140 toward the cap, thereby tensioning spring 148 until catch 152 moves behind a pair of shoulder or surfaces 182 and 184 (FIG. 7

As the latch is raised, it is forced counterclockwise relative FIG. 6 about its segment 170 as a result of engagement with said

shoulders

182 and 184 which comprises a cam relative which latch 165 is a follower. The shoulders slope upwardly as they extend outwardly and are generated in a plane by housing 132 on opposite sides of vertical slot 154. The parts are proportioned such that latch 165 loses control of impactor at substantially the same time striker 178 loses control of arm 166. Thereupon, impactor 140 is driven downwardly as s ring 148 untensions to close switch 120.

A torsion spring 186 (FIG. 6) has opposite end portions bearing against the upper surface of wall and end portion 168 of arm 166. Said torsion spring is arranged for biasing arm 166 clockwise relative FIG. 6 about pivot pin 172 and facilitates restoration of said arm to a normal position upon return of cap 156 following depression. The arrangement of parts also enables striker 178 to clear said end portion 176 as the cap is restored to its normal position.

A pin 188 which extends transversely of slot 154 causes the lower end portion of latching structure 164 to bend counterclockwise relative FIG. 6 as latch is cammed out of latched engagement. In consequence, a tension builds in structure 164 which biases it-to a restored position following cap release after depression.

As many modifications in the described construction could be conceived, and as many changes could be made therein without departing from the spirit and scope of the claims, it is intended that all matter contained in the accompanying specification shall be considered as illustrative only and not in a limiting sense.

Iclaim:

1. An electrical switch comprising:

a plurality of bodies having flexible conductive portions disposed in a stack and having a normal position in which said conductive portions are spaced apart each from an adjoining thereof;

an impactor arranged in alignment with said bodies adjacent the flexible conductive portion of the body disposed at one end of said stack, said impactor having a first condition in which said contacts are in their normal position and a second condition in which said flexible conductive portions are engaged;

means for tensioning said impactor while in said first condition;

means for releasing said tension;

means for driving said impactor to said second condition after tension release;

an elongated housing with a chamber, said impactor arranged for reciprocation in said chamber longitudinally of said housing, said stack being supported outside said chamber, and

a cap associated with said tensioning means and disposed for reciprocation between normal and depressed positions about said stack and outside of said housing.

2. A combination according to claim 1 further characterized by a plurality of electrical leads connected from said bodies and extending longitudinally of said housing.

3. A combination according to claim 2 wherein said cap comprises a shell having an open end and disposed about said housing and wherein said leads are arranged along the outside of said housing within said shell and have end portions projecting from said open end.

4. A combination according to claim 1 characterized by:

a retainer spaced from said outer surface, said retainer having first and opposed surfaces disposed proximately and distally of said stack, respectively, and

a compression spring bearing against said retainer for restoring said cap to an extended position following key depression.

5. In a key assembly of the type having an impactor reciprocatively arranged within a housing for producing an effect in response to release of spring tension resulting from movement of a self restorable depressible cap, and wherein a tension release means comprises a cam for removal of an impactor restraint which prevents tension release during a part of a cap depressing stroke inwhich spring tension is generated for biasing said impactor toward an effect producing aspect, a combination wherein:

said housing has a wall with an aperture and defines a chamber,

said cam is fixed relative said housing,

said impactor has a body arranged for movement in said chamber upon release of spring tension and a projection disposed in said aperture and extendable therefrom for producing said effect; and having a base, said housing having a vertical orientation with an open lower end secured to said base,

said wall having an upper surface, a lower surface and an aperture therethrough and comprising an upper end portion of said housing,

said projection having an upper impacting end,

said spring having a lower end bearing against said base for urging said impactor toward said lower surface and having an untensioned condition in which said upper impacting end is disposed at the level of said upper surface and a tension release condition in which said upper impacting end extends upwardly beyond said upper surface.

6 A combination according to claim wherein said cap comprises a shell circumposed about said housing and has a part extending into said housing for releaseably depressing said impactor, and characterized by a releaseably compressible member disposed within said shell for restoring said cap to a start position from a depressed condition.

7. [n a key assembly of the type having an impactor reciprocatively arranged within a housing for producing an effect in response to release of spring tension resulting from movement of a self restorable depressible cap, and wherein a tension release means comprises a cam for removal of an impactor restraint which prevents tension release during a part of a cap depressing stroke in which spring tension is generated for biasing said impactor toward an effect producing aspect, the improvement comprising:

means responsive to depression of said cap for moving said impactor toward said cap to tension said spring.

8. A combination according to claim 7 characterized by a catch carried from said impactor and wherein said moving means comprises an arm arranged for rocking in response to said cap, and said restraint is connected to said arm and comprises a latch arranged for engagement with said catch to tension said impactor.

9. A combination according to claim 8 wherein said latch is proportioned for following engagement with said cam, said cam being fashioned for moving said latch from tensioning association with said impactor during depression of said cap.

10. A combination according to claim 9 wherein said housing has an upper end portion with a lip, said cap comprising a shell circumposed about said housing and having a dog arranged for engaging said lip for limiting upward movement of said cap following release from depresSion.

11. A combination according to claim 10 wherein said housing defines a chamber with upper and lower end sections, said impactor being disposed in said lower end section, said housing having an upper wall, said spring disposed in said upper end section and bearing against said impactor and said upper wall, and characterized by expansible means disposed within said shell and arranged for bearing against said upper wall for restoring said cap following release from depression thereof.

12. A key assembly comprising:

a housing having a chamber and an aperture;

an impactor having a body arranged for movement in said chamber and a part movable through said aperture for producing an effect in response to release of spring tension;

a first spring bearing against said impactor;

a cap depressibly mounted about said housing and arranged for moving said impactor and tensioning said first spring for impactor return;

a second spring arranged for urging said cap away from a depressed position;

restraining means for preventing impactor return during cap depression; and

a camming element arranged for removal of said restraint during depression of said cap.

* II R t

Claims

1. An electrical switch comprising: a plurality of bodies having flexible conductive portions disposed in a stack and having a normal position in which said conductive portions are spaced apart each from an adjoining thereof; an impactor arranged in alignment with said bodies adjacent the flexible conductive portion of the body disposed at one end of said stack, said imPactor having a first condition in which said contacts are in their normal position and a second condition in which said flexible conductive portions are engaged; means for tensioning said impactor while in said first condition; means for releasing said tension; means for driving said impactor to said second condition after tension release; an elongated housing with a chamber, said impactor arranged for reciprocation in said chamber longitudinally of said housing, said stack being supported outside said chamber, and a cap associated with said tensioning means and disposed for reciprocation between normal and depressed positions about said stack and outside of said housing.

4. A combination according to claim 1 characterized by: a retainer spaced from said outer surface, said retainer having first and opposed surfaces disposed proximately and distally of said stack, respectively, and a compression spring bearing against said retainer for restoring said cap to an extended position following key depression.

5. In a key assembly of the type having an impactor reciprocatively arranged within a housing for producing an effect in response to release of spring tension resulting from movement of a self restorable depressible cap, and wherein a tension release means comprises a cam for removal of an impactor restraint which prevents tension release during a part of a cap depressing stroke in which spring tension is generated for biasing said impactor toward an effect producing aspect, a combination wherein: said housing has a wall with an aperture and defines a chamber, said cam is fixed relative said housing, said impactor has a body arranged for movement in said chamber upon release of spring tension and a projection disposed in said aperture and extendable therefrom for producing said effect; and having a base, said housing having a vertical orientation with an open lower end secured to said base, said wall having an upper surface, a lower surface and an aperture therethrough and comprising an upper end portion of said housing, said projection having an upper impacting end, said spring having a lower end bearing against said base for urging said impactor toward said lower surface and having an untensioned condition in which said upper impacting end is disposed at the level of said upper surface and a tension release condition in which said upper impacting end extends upwardly beyond said upper surface.

6. A combination according to claim 5 wherein said cap comprises a shell circumposed about said housing and has a part extending into said housing for releaseably depressing said impactor, and characterized by a releaseably compressible member disposed within said shell for restoring said cap to a start position from a depressed condition.

7. In a key assembly of the type having an impactor reciprocatively arranged within a housing for producing an effect in response to release of spring tension resulting from movement of a self restorable depressible cap, and wherein a tension release means comprises a cam for removal of an impactor restraint which prevents tension release during a part of a cap depressing stroke in which spring tension is generated for biasing said impactor toward an effect producing aspect, the improvement comprising: means responsive to depression of said cap for moving said impactor toward said cap to tension said spring.

12. A key assembly comprising: a housing having a chamber and an aperture; an impactor having a body arranged for movement in said chamber and a part movable through said aperture for producing an effect in response to release of spring tension; a first spring bearing against said impactor; a cap depressibly mounted about said housing and arranged for moving said impactor and tensioning said first spring for impactor return; a second spring arranged for urging said cap away from a depressed position; restraining means for preventing impactor return during cap depression; and a camming element arranged for removal of said restraint during depression of said cap.