US2677730A

US2677730A - Thumb switch

Info

Publication number: US2677730A
Application number: US202863A
Authority: US
Inventors: Sr William T Weidenman
Original assignee: Telephonics Corp
Current assignee: Telephonics Corp
Priority date: 1950-12-27
Filing date: 1950-12-27
Publication date: 1954-05-04
Anticipated expiration: 1971-05-04

Description

'May 4 1954 w. T. WEIDENMAN, SR 2,677,730

THUMB SWITCH Filed Dec. 27. 1950 INVENTOR WILLIAM T WEIDENMAN) SR.

Patented May 4, 1954 UNITI-:D us'mrs ATENT OFFICE THUMB SWITCH Application December 27, 1950, Serial No. 202,863

(Cl. Zilli-5) 2 Claims. 1

This invention relates to switches, and has particular reference to the on-and-oif type of switch used in hand microphones or telephones, although the invention is not limited to that use.

In aircraft, naval and military neld communications, it is desirable that the microphone be disconnected except during period of use, and it is also desirable that the transmisison power unit be kept out of service except when in actual use. Accordingly, it has become the general practice to provide a thumb or other finger switch button in the handle of the microphone or telephone handset so that it may be conveniently pressed to successively close two circuits and successively reopen the circuits in reverse order when the button is released. The iirst circuit closure activates the transmission power unit, and the second circuit closure energizes the microphone and, when the button is released, the microphone is first disconnected and then the transmission power unit is cut out of service. An example of a switch performing these functions in a satisfactory manner is disclosed by Patent No. 2,666,022, issued December 29, 1936 to applicant, and the present invention is an improvement on the switch of said patent.

In accordance with the present invention, a switch particularly adapted for thumb or nger operation in hand microphones or telephone handsets is provided which is compact, moistureproof, and positive in its operation during most rigorous usage in the field.

In a preferred embodiment of the invention, the two successively operated switches are mounted on opposite sides of an elongated block of insulating material carried on the underside of the mounting plate which fits flush with the surface of the microphone or handset handle with the block recessed within the handle. Leaf spring blades carrying one of the contacts of each switch are normally urged to contact disengaging position by reason of their self springiness, but are spread apart to engage the correspending opposite contacts by a plunger extending through the mounting plate and into the insulating block between the leaf spring contact blades and normally urged outwardly to contact disengaging position. Spaced different distances from the leaf spring contact blades so as to be successively engaged thereby are fixed contacts mounted on the block. Pivoted on the outer surface of the mounting plate and extending across the plunger so as to move the same into the block, is a press lever shaped to be comfortably engaged by a thumb or finger of the hand holding the microphone or handset.

Preferably, the aforementioned switch is sealed against moisture and to that end, the insulating contact block normally recessed within the handle is enclosed within a casing moisturetightly sealed against the underside of the mounting plate. Connection to the switch contacts is made by means of terminals on the outside of the casing which are connected to the contacts within the casing. Extending over the external thumbor finger-operated lever is a hood of flexible rubber which is secured moisturetightly to the outer surface of the mounting plate and of the surrounding handle surface by means of the washer held by the mounting screws of the plate. The rubber hood is flexible and pressure on it actuates the thumb or finger lever. The hood may be omitted when another improvement of this invention is incorporated in the switch, and that is the separation oi the switch actuating plunger into two axial sections and sealing the outer one moisture-tightly in the mounting plate opening through which the plunger extends for engagement by the thumbor linger-actuated lever.

It will be seen that the thumb switch of this invention is compact, eicient and fool-proof for performing its intended functions reliably under the most adverse operating conditions, including rain, fog, and even when submerged in water for a substantial period of time.

For a more complete understanding of the invention, reference may be had to the accompanying drawings, in which:

Figure 1 is a side view of the switch of this invention, portions being broken away to expose operating parts for clarity;

Fig. 2 is a transverse section thereto as seen along the line 2 2 of Fig. l; and

Fig. 3 is a vertical section through the switch as seen along the line 3 3 of Fig. 1.

Referring to Fig. 1, numeral Il) designates the handle of a telephone handset, although it be the handle of a microphone or the like, which is mounted at a point where the lingers or thumb of the hand holding the handset or microphone engages the surface of the handle, is the switch of this invention, generally designated Il.

As shown in Figs. 1 and 3, a mounting plate l2 is recessed into the surface of the handle lil so as to be flush and it is generally rectangular in shape, being secured to the handle It by screws I3 or other suitable fastening means. The handle Ill is provided with an opening iii immediately below the mounting plate I2 which accommodates the insulating block I5 secured to ing nat surfaces of the insulating block l that lie immediately behind thecorresponding contacts 22 and 23. Blade 2|) is provided at its upper edge with the outwardly flaring ear 24- andi Iblade 2| is similarly provided at the upper edge with the outwardly flaring ear 25.

The

ears

24 and 25 are located opposite the Vertical passage |"|A through: then block` andf a.

plunger 26 is: mounted within thepassage il and provided withan enlarged flaredportion 2l adapted to engage the ears 2li and 25 as shown particularly in Fig. 3. Downward pressure on plunger 26 causesy theenlarged= portion 2l-1V 'thereof to force the' ears 24 andr25-and consequently corresponding contacts` 2.2.v and in opposite, outward directions away fromv the' block l5.

Plonger Zisnorrnally urged in an'upward or outward direction-so asto normally 'release pressure against earsZ/-l1 and.` 25, this. urging action being effectedby. ai spring. 23'. extending acrossV the bottom ofthefinsulatingblock l'and at. its oppositefends thereto byclamping means 29. directed hump engaging thelower. endof plunger 2B and has concave portions at'eit-her side of the central hump. A: spring soshaped has the characteristics described in saidy patent of present-- ing a m'ax'imumresistancev to the downward movement ofthe plunger 26 upon initiall move-- ment thereof, and decreasingVY such resistance on continued movement of the-plunger.- 26,.so as to aiord aninitial resistance of the pressure of the thumb or finger' and torestcre the plunger rapidly and positively when.` the pressure ltfiereonv is released.

The contacts- 22` and 23` are normally spaced from cooperatingY xed contacts` 3.0 andI 3 l, respectively, carried

ony contact springs

32 and 33 scoured to the insulating block I5 by screws all and 357 as shown particularly inFigs. 14 and 2. Stationary contactLSi'll is spacedacloser to movable Contact 23y than.- is' stationary contact 3b from. movable contact 22, so that on downward movement of the plunger'ZB. contact 23; engages contact 3| before Contact 22- engages Contact 35i. Contacts 23. and 3| close the power circuit and closure of contats'22 and 3|). close the microphone circuit a fraction ofaI second thereafter with the reverse operation taking place when4 the pressure is released. and spring 28-urges thevplunger' 26 upwardly. The resiliencyof. stationary oontact springs 32 and 331 causes them` to. retract when their respectiver contacts 3c. and 3| are engaged and the resulting. wiping movement between the contacts keeps them clean.

Pivoted at one end on suitable ears 3G on the outer surface-ofl mountingplate |12 is the thumb or iinger lever 3i! whose free end is.l guided by. a vertical pin 38 extending. upwardly from mounting plater |2. and telescoped in. a. cylindrical guide39 ontheunderside of lever 31. As shown particularly in Fig. 3,.lever 31 is channel-shaped and presents. a smooth, comfortable Spring 28" is shapedV with an inwardly-- surface to the operators finger or thumb. The under surface of lever 31 at approximately its longitudinal and transverse center engages the extension 26 of the plunger 26 which is shown in substantially mid-position in Figs. l and 3. In this position of the lever 31, contacts 23 and 3| liavebeen closed, butcontacts-Z'Z and 30 remain open. In` normally disengaged position, lever 31 lies as shown in phantom in Fig. l.

Preferably, switch is rendered moistureprooi. in accordance with this invention. Secured' as by soldering or brazing 'to the under surface ofi mountiinrtA plate 2 is a" rectangular housing 40'? having a central opening 4| which is sealedmoisture-tightly by an insulating plate 42. Insulating plate, 42 carries the terminals 43 to which the corresponding terminals 44 within the casing 4B are suitably connected in a well-known manner, so that the contacts withinA the casing; 4|) F are properly connected.; into f the' cireuits=which `they control;

cludingthev contacts 22:, 23 33 andi 3 l-4 are moisture-tightly sealed to the underside ot the mounting plate l2.

The-entire switch is-not'lcompletely moistureproof ecause plungerv 26 extends. through the mounting. plate.. |-2. mounting. plate l2. is provided withi threaded upwardly Collar decir whichis-screwed the cap 4b throughA flange iQ-of the hoodiislarger. than4 the mount-1 ing plate so` thatflange, 49, overlaps-the surface of the handle lil, beyond the perimeter of the mounting plate: I2V as shown particularly in Figs. l and. 3I Ametal` washer or collar: 5Eloverlies the rubber flange 49 of.` the hood 48, and. clamps it againstI the outer surface of the mounting plate l2 and the overlapped surfaceofthe .handle lo so astotseal the flange, 49 moisture-tightly thereto. Pressure onthe flexible hood by the thumb` or finger actuatesthelever 31. and when the pressure'is.. released, the resiliency of. hood 4B causes it to restore itself. to-thenormal shape shown in Figs. l and. 3.

Operation` ofthe thumb. or finger. switchy of, this invention. is readily undinstcod from. the foregoing. description. and although. preferred embodiment of. the inventionhas beenv illustrated and describedhereim it is to baunderstcod that the invention is susceptible. of changesin. form and detail. withim the scope of thev appended claims.

I claimz.

l. In a switchfor. hand .microphones like, the. combination.. of. an. insulary ig., rnembe; having firstand. second. intersecting. ai

:nut ly perpendicular passages., a. of. cantilc blades respectively. mountedat.. oneenfl on op.- posite sides of saidv member in., spaoed.- parallel relation, saidblades being disposed adjacent opi'- posite ends ofsaidlrstpassagaa Contact'. at the free endofl'eacli said blade,.a pair of` relatively In-thismanner; theY insulating-block. 5 and-its appurtenant..partsf,i in-` However,V the.

stationary contacts mounted respectively on opposite sides of said member and normally spaced from the corresponding said blade contact, a plunger mounted in the second passage and movable in said member transversely of said blades and between the same, an enlarged portion on said plunger disposed within the member and also disposed at least partially in said first passage and adapted on movement thereof in one direction to deiiect said blades to engage said blade contacts with the corresponding said stationary contact, a handle connected to said plunger for moving the same in said one direction, means defining an elongated channel in the underside of said insulating member intercepted near its center by said second passage, and spring means comprising an elongated metallic strip member attached at opposite ends to said insulating member to overlie said second passage to be disposed in the path of movement of the plunger, said strip member being bowed inwardly in the direction of the plungerfor normally urging said plunger in the opposite direction toward contactudisengaging position.

2. Ina switch for hand microphones and the like, the combination of a mounting plate secured to the hand grip of the microphone, an insulating member on the underside of said plate, a cantilever blade mounted at one end on said member, a contact at the free end of said blade, a relatively stationary Contact mounted on said member and normally spaced from said blade contact, a plunger movable in said member transversely of said blade, an enlarged portion on said plunger adapted on movement thereof in one direction to deiiect said blade to engage said blade contact with said stationary contact, a pin aligned with said plunger and projecting through an opening in said plate and beyond the outer surface thereof, a iiexible sealing means interposed between said pin and said plate and joined in sealing the relationship to each to seal the opening in the plate against the passage of moisture, a cup enclosingsaid member and appurtenant contacts and sealed to the underside of said mounting plate, ja handle connected to said pin for moving said plunger in said one direction, a, llexible, moisture-impervious hood enclosing said handle and pin and attached in moisture sealing relationship to the top side of said mounting plate, whereby the switch and appurtenant contacts are enclosed in a moisture tight housing sealed bymeans of said flexible sealing means, plate and cup and whereby said handle and pin are sealed by said plate and hood and spring means normally urging said plunger in the opposite direction toward contact-disengaging position.

References Cited in the le of this patent UNITED STATES PATENTS Harrison Feb. 22,