US3373256A - Flush pushbutton switch with substantially simultaneous actuation - Google Patents

Description

March 12, 1968 B. R. REED 3,373,256

FLUSH PUSHBUTTON SWITCH WITH SUBSTANTIALLY SIMULTANEOUS ACTUATION Filed Jan. 25, 1966 2 Sheets-Sheet 1 FIG! IA/ VET/TOR. BUCKL E Y A. REED B. R. REED March 12, 1968 3,373,255 FLUSH PUSHBUTTON SWITCH WITH SUBSTANTIALLY SIMULTANEOUS ACTUATION 2 Sheets-Sheet 2 INVENTOR. BUCKLE) R. REED Filed Jan. 25, 1966 1 ATTORNEYS.

United States Patent Oflice 3,373,256 Patented Mar. 12, 1968 3,373,256 FLUSH PUSHBUTTON SWITCH WITH SUBSTAN- TIALLY SIMULTANEOUS ACTUATION Buckley R. Reed, Valley Station, Ky., assignor to K. M.

White Company, Louisville, Ky., a corporation of Kentucky Filed Jan. 25, 1966, Ser. No. 522,955 4 Claims. (Cl. 200-159) ABSTRACT OF THE DISCLOSURE A pushbutton switch having two movable contacts disposed in a common plane perpendicular to that in which the force is normally applied and arranged to be advanced by the button, has added hereto a yoke pivotally mounted in the switch and adapted to be depressed by the pushbutton for uniformly and contemporaneously activating the contact members.

This invention relates to elevator control switches and in particular to those of the illuminated type.

In addition to the usual considerations of short button stroke, adequate contact gap, long contact life, minimum maintenance, etc., elevator switches of the self-illuminating type generally require an additional set of contacts which may, for example, be connected in circuit with the illuminating bulb. Because it is advantageous to have elevator control switches as shallow as possible, the additional contacts are generally placed in the same plane as those supervising the control system. Consequently, when the button is depressed, the same travel is utilized to close both sets of contacts.

If, when the pushbutton is depressed the control systern contacts make before the light contacts, then the operator will assume that the control system has not operated and will re-manipulate the pushbutton until the light indicates that the control system contacts have been made. This useless manipulation has a counterpart; that is, if the light contacts make before the control system contacts, the button will light and yet will convey no information to the elevator control system. Further, regardless of the circuits which the contacts control, the making of either set gives the incorrect sensation of bottoming. As a consequence of the foregoing, it becomes important to ensure that both contacts make substantially simultaneously and it is toward this end that the present invention is directed.

Accordingly, it is the object of this invention to provide an improved flush pushbutton switch of the illuminated type in which each set of contacts makes substan tially simultaneously with the others.

It is a further object of this invention to accomplish the foregoing object without increasing the overall dimensions of conventional pushbutton switches, and to do so in a manner which is economical both in manufacture and in maintenance.

The above mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will best be understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is an exploded perspective view of the illuminated switch according to the invention;

FIGS. 2 and 3 illustrate the switch in side and end elevation views respectively.

Turning now to the invention, and in particular to FIG. 1, the illuminated switch according to the invention may be seen. Rather than confuse that which follows with constant references to the drawings, it is to be understood that references will be made to the drawings generally and that the particular element being described may be found in one or more views.

The switch comprises a main body 10 that is of substantially rectangular outline having a main base portion 11 from which there extends two substantially similar rectangular end members 12 and 14. Disposed between the end members is block 15, also of generally rectangular shape, embracing cylinder 16, the purpose of which is to admit and retain a bayonet-type lamp which, as will be explained hereinafter illuminates the switch. The lamp is retained in a lamp socket 18 mounted in the cylinder 16.

With the exception of the lamp attitude, and a few additional modifications (including, needless to say, that of the invention), the switch shown in FIGS. 1 through 3 is similar to that of my Patent No. 3,127,493, to which reference is made for additional structural details.

Disposed on either side of the central block 15 are spring contact members 2-1) and 21, each provided with contact buttons 22 and 23 at the end thereof. As will be described further hereinafter, upon pressure being applied to the pushbutton 45, the spring contact members force their associated contact buttons against corresponding contacts 24 and 25 for completing the respective circuits.

Before entering upon a detailed explanation of the yoke member 30, its purpose and its function, the pushb-utton switch will be explained without this element so that the reason therefor will be more fully appreciated.

Pushbutton 41 is situated above the main body 10 and includes a cavity 41 for admitting block 15 therein. The bottom of the button is flanged and includes two depending projections 42 and 43, each of which is urged upon the yoke upon the application of a force at the top.

The pushbutton is itself slidable within the covering cap 51 which is fastened to the main body end members 12 and 14 by any suitable means such as screws 51 through 54. Preferably, the top of the button 40 is flush with the top of the mesa 55 of the cap 50. If desired, the cap portion surrounding the button at the top may be recessed so that a finger may suitably find the button. As may be seen, the pushbutton rides within a sleeve portion 56 formed within the cap member. Excursions of the button axially are limited by the tolerancing between the outer periphery of the button and the inner periphery of the sleeve, as Well as the button cavity portion 41 which sits astride the rectangular block 15.

One of the chief costs of manufacturing is dependent upon this tolerancing between the button and cap. If the tolerancing is too exacting, particularly where the elements are made out of plastic, the device becomes infeasible. Consequently, in buttons of the type shown, the spacing between the outer periphery of the button and the inside of the cap is suflicient to allow play. Because of this play, when the button is depressed as shown by either of the arrows 1 or 2 (as opposed to the arrow 3), the button tends to axially misalign, resulting in the contacts adjacent to the force, making first. While recent advances in the art have allowed closer tolerancing at substantially the same cost, the problem alluded to has not been eliminated.

Yoke 30 solves this problem. The yoke is seated in the main body by means of projections 31 and 32 which enter corresponding main body grooves 27 and 2-8 and are retained therein by a pair of shaped keepers 34 and 35. Upon either of the button projections 42 or 43 striking the corresponding groove (36 or 37) in the yoke, the whole yoke is uniformly angularly displaced, causing both yoke ends 38 and 39 to descend at a uniform rate against contact members 20 and 21. Projections 4-2 and 43 on the button flange ensure proper pivot and fulcruming against the yoke member.

The return of the pushbutton to its normal position is achieved by the resiliency in the contact members which, after removal of the actuating force, act upon the yoke, which in turn acts upon the button. The length of the yoke arms 38 and 39 is dependent upon considerations of the force necessary to close the contacts and the required contact gap.

The electrical connections to the bulb, as well as the contact pairs may be made via the bolt, nut and lock washer groups 4 through 9 conveniently located at the back of the switch for this purpose.

As will be apparent from the foregoing, the improvement according to the invention not only makes it impossible to cock the button; i.e. push the button sufliciently out of alignment so that it remains in that position, but further, it alleviates the problem of the making of one contact pair without the making of the other.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. In a pushbutton switch of the type having at least two movable contacts, disposed substantially in a plane perpendicular to that through which the force on the button is normally applied, and arranged to be advanced by the button, the improvement comprising a yoke pivotally mounted in said switch, said yoke having a number of arms corresponding in number to the number of contacts to be depressed and disposed between said pushbutton and said contacts, each arm of said yoke being equidistant from its associated movable contact for uniformly actuating said contact members upon motion being imparted to said yoke by said button.

2. An illuminated pushbutton switch comprising a base member; a cap member disposed above said base member; a pushbutton axially slidable in said cap member; at least a pair of movable contacts disposed in said base member for contact by said pushbutton during its travel towards the base member; and a yoke pivotally mounted intermediate said cap and base portion having at least a pair of arms each disposed between one movable contact member and said pushbutton for actuation by said pushbutton upon the travel of said button towards said base, whereby when either arm of said yoke is actuated, said yoke is angularly displaced and is urged upon all of said contact members simultaneously.

3. The pushbutton claimed in claim 2 wherein said yoke comprises a pair of arms; said yoke further having a pair of projections perpendicular to said arms for the pivoting thereof.

4. The pushbutton claimed in claim 3 in which the base member has a pair of channels for accommodating said projections and allowing the arms to pivot therein; said pushbutton further comprising a pair of keepers, each entering a corresponding channel above said projections for maintaining said yoke in position.

References Cited UNITED STATES PATENTS 2,482,206 9/ 1949 Pratt ZOO-453.8 2,695,939 11/1954 Filliette 200-153.8 3,127,493 3/1964 Reed 200-167 3,188,437 6/ 1965 Lauren et al 200-l67 FOREIGN PATENTS 829,734 3/1960 Great Britain.

ROBERT K. SCI-IAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

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