US2431904A

US2431904A - Push-button switch

Info

Publication number: US2431904A
Application number: US569296A
Authority: US
Inventors: Andrews John Lewis
Original assignee: HOTPOINT Inc
Current assignee: HOTPOINT Inc
Priority date: 1944-12-22
Filing date: 1944-12-22
Publication date: 1947-12-02
Anticipated expiration: 1964-12-02

Description

Dec. 2, 1 947. J. l.. ANDREWS 2,431,904l

PUSH BUTTON SWITCH inventori: John Lewis Andrews,

9 His Attorney Dec. 2, 1947; J. l.. ANDREWS v 2,431,904

A PUSH BUTTON swITcn Filed'nec. 22, 1944 5 sheets-sheet 2 Y Ihentor': John Lewis Andrews,

b5 His Attorney.

Dec. 2, 1947. J. L. ANDREWS PUSH BUTTON SWITCH Filed Dec. 22, 1944 5 Sheets-Sheen; I5

J3? Inventor-z John Lewis Andrews,

his Attorney.

Deck. 2, 1947. J. L. ANDREWS PUSH BUTTON SWITCH Filed Dec. 22, 1944 5 sheets-sheet 4 ttor-neg.

inventor: y YJohn Lewis Andrews,

His

Filed Dec. 22, 1944 5 Sheets-Sheet 5 A i I /lf f /aa /u w a.

Dec. 2, 1947. J. l.. ANDREWS 2,431,904

PUSH BUTTON SWITCH Invento: John Lewis Andrews',

by Wwf-7J His Attorney.

Patented Dec. 2, i947 PUSH-BUTTON SWITCH John Lewis Andrews, Fairfield, Ill.. assigner to Hotpoint Inc., a corporation of New York Application December 22. 1944, Serial No. 589,298

11 Claims. 1

The present invention relates to push button switches of the type which include a plurality of push buttons for actuating slides to effect closing fof one or several deiinite electric circuits upon the actuation of one push button and simulta neously preventing the operation of another push button through suitable interlocking mechanisms.

The object of my invention is to provide an improved construction an'd arrangement of push button switches oi the type above speciiled which are comparatively simple in construction and safe and reliable in operation.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing.

In the drawing Fig. 1 is a top view of a push button switch embodying my invention associated with an electric kitchen range; Fig. 2 is a bottom view of the switch in Fig. i; Fig. 2a is'an exploded perspective view of certain parts of Fig. 2; Fig. 3 is a section along line 3-3 of Fig. 1; Fig. 4 is a section along line 4-4 of Fig. 3; Fig. 5 is a perspective view of the base of the switch; Fig. 6 is a diagrammatic view oi certain parts of the switch; Figs. 7 to i2 inclusive are diagrammatic views of certain parts oi the switch in dierent operating positions in connection with a kitchen range heating unit; Fig. 13 illustrates a modification of a switch embodying my invention; Fig. 14 is a section along line I4 of Fig. 13; and Figs. 15 and 16 are exploded perspective views of certain parts of the switch of Fig. 14.

The arrangement of Fig. 1 comprises an electric kitchen range with a range top I accommodating a surface heating unit II. The unit II is of known design and as indicated in Figs. 7 to l2 inclusive includes two electric heating elements i2, I3, each of which has one end connected to a common conductor I4 and another end connected to conductors I and I6 respectively. In order to provide for different heats or heat outputs means are provided for connecting one or both heating elements I2, I3 in parallel toi-220 volts or in series to 110 volts and also to connect one of the elements to 110 or 220 volts, thus producing five different degrees of heat outputs and requiring a circuit arrangement with ve different operating connections.

(Cl. 20o-5) 48 and either of the outer' terminals 41, 49 is 110 These ilve circuits are produced by a push button switch which has a base I1 made of plastic or like insulating material. The base in the. present example is supported on the rear of a backsplash I8 of the kitchen range by means of two brackets Il, 20 (Figs. 1. 2) and only certain actuating elements of the switch are visible from the iront of the backsplash and project through an opening 2I thereof. The base forms a contact chamber closed by an insulating cover 24 and a plurality of pockets, in the present instance six, 28 (Fig. 5) communicating with each other and with the contact chamber 22. The pockets 25 are of equal size, substantially rectangular in section ,and deilned by the end walls of the base and a row of ve parallel partitions 2B between the iront and rear wall of the casing. The partitions have aligned openings-21, thus forming a channel for accommodating a plurality of slides, in the present instance four, 2,8, 29, 30 and Il (Fig. 4). Generally. opposite side walls of the base are provided with parallel aligned ribs having rounded edge portions 32 and connectedat their upper ends by cross bars 33. A pair of opposite ribs and a cross bar together form a partition 26 and the partitions form pockets with aligned openings 2T for receiving the aforementioned slides 28 to 3i inclusive. Six push buttons 35 to 40 inclusive project into and are guided in the pockets for actuat ing the slides 28 tc 3l. Each push button has a plunger 4I stamped from metal with a lower U- shaped portion and legs 42, 43 made of insulating material and secured to opposite sides of the U-shaped portion of the plunger 4I., The insulating legs 42, 43 (Fig. 6) have aligned openings 44 for receiving a pin 45. Aseparate button 48 (Fig. 4) made of plastic material is molded to each plunger 4I and when assembled with a range, as in Fig. 1, projects through the opening 2| of the backsplash.

The electric circuit elements of the switch include three

terminals

4l, 48 and 48 for connection to three conductors 50, 5I and 52 (Figs. 'I to 12) of a 220 volt line. The conductor 5I constitutes the neutral and is connected to the middle terminal 48 whereas the outer conductors 50, 52 are connected to the terminals 41 and 48 so that the potential between the middle or neutral terminal volts while the potential between the outer terminals 41, 49 is 220 volts. Each terminal 41, 4l.

49 includes a bar 53, 54 and 55 respectively whichy bars are securely fastened to the base by means of separate metallic eyelets 58. The bars 53, 54 and 55 arey provided with stationary contacts l1 (Fig. 4). The bar 53 carries one such contact and each oi the bars 54. BU carries two contacts.

`The stationary contacts 51 are cooperatively associated with movable contacts 8l. Fig. 4, attached to the free ends of contact springs or blades 53 to 33. Each spring has an intermediate portion curved in cross section to give the blades a certain stiiness and another end portion attached to the insulating base. In order positively to locate the other end portions these blades are provided with opposite V-shaped projections 34 iltting into corresponding V-shaped recesses 35 formed in the back of the base.

Switches designed for use on electric heating appliances are usually subjected to higher ambient temperatures ordinarily encountered on other devices. Therefore, extra precautions must be taken to provide means to assure a positive electrical contact regardless of possible loosening or shrinkage that may take place in the molded insulated base. This is accomplished in accordance with my invention by providing the ilxed ends of each contact blade with a curved portion 55 projecting into corresponding recesses 31 in the base. The two spring blades.59 and 63 are electrically connected at their fixed ends by a cross bar 68 and the spring blades 3|, 62 at their fixed ends are similarly electrically connected by another cross bar 68. Each of the spring blades is securely fastened to the base by means of a hollow rivet 39. The rivets serve to attach the cross bars 68 to the respective blades 59 to 32. If during operation the base should shrink or the rivet or like electrical connecting means becomes loose, the curved end portions 66 of the spring blade produce sufficient spring action or exert a biasing force to assure positive electrical contact between the blades, the respective cross bars, and the hollow rivets 69. During installation the conductors 4, I5 and i6, Fig. 7, are electrically connected to the contact springs 59. 33 and 3| respectively by means of terminal screws 59a projecting through the hollow rivets 59 associated with said contact springs,

The various circuit connections are accomplished by effecting opening of some and closing of others of the contacts upon actuation of the slides 28 to 3| inclusive. In one position, Fig. 7. the slides, more particularly the ends thereof, are in alignment. In this position the olf button 35 is pushed in to effect opening of all contacts.

Each of the slides 23 to 3| has six apertures a to f respectively, hereafter designated with the numeral of the slide and the letters a to .f respectively. Thus, the aperture 3|a designates the upper aperture (Fig. 7) of the slide 3|. All apertures in the present example are in the form of substantially rectangular triangles with rounded corners. The pins 45 of the push buttons project through an aperture in each slide and with regard to such aperture are located either in the rounded corner formed between the sides or in the corner formed between one side and the hypothenuse or diagonal. From another viewpoint, the pin 45 upon being pushed in or out either slides along a side of the rectangular triangle or along the hypothenuse thereof. This means that whenever a pin slides along a side of one of the rectangular triangles it will not effect movement of the corresponding slide, whereas whenever a pin moves along the hypothenuse or diagonal which also might be called a working surface it will effect a lateral displacement or sliding movement of the respective slide. Thus, with regard to the slide 3l (Fig. 7), pushing of the

buttons

35 and 31 to 43 will not eifect vertical displacement of the slide 3|, whereas pushing of the button 36 causes upward movement of the slide 3| (Fig. 12).

One or two apertures of each slide forms an 4 ear for locking a button in position once it is pushed in. Thus, the aperture 23! forms an ear 13 which locks the push button 35 in position when pushed in. The push button 33 when pushed in is locked in position by an ear 1| formed by the aperture 3 le, and the push buttons 31 to 43 inclusive are respectively locked in position when pushed in by ear 12 formed by aperture 33d; ear 13 formed by aperture 23e; ear 14 formed by aperture 33h; and ear 15 formed by aperture 29a respectively.

Adjacent surfaces of the slides 23 to 3| are provided with bosses 13 slightly to separate adjacent slides and thus to reduce frictional resistance upon relative movement of the slides. The outer surfaces of the outer slides 23, 3| slide along the rounded edge portions 32 formed by the base `which oifer little resistance to movement of the outer slides.

Each slide has an edge adjacent the cover 24 forming a plurality of projections and cam surfaces. Two of the projections 11, 13 form small bearing surfaces which may be termed bearing projections engaging the bottom or cover 24 of the base. Other projections constitute cam surfaces or contact blade actuating projections. Thus the slide 3| has three projections or cam surfaces 19, 33 and 3| which in certain positions of the slide 3| engage the

contact blades

33, 3| and 63 respectively to force said springs away from the stationary contact buttons 51. The slide 33 has three

cam surfaces

32, 33 and 34 which in certain positions of the slide force into open position the

contact blades

33, 33 and 59 respectively. The slide 29 has three

cam surfaces

35, 33 and 31 cooperatively associated with the

contact blades

33, 32 and 53 respectively. Finally, the slide 23 has two

cam surfaces

33 and 33 in cooperative relation with the

contact blades

33 and 33 respectively.

Each slide should be in one of two positions for any operating l.condition of the push button switch. In order to fix these two positions I provide indexing means. These indexing means in the present example comprise a projection 93 on each slide. All projections 33 in the off position (Fig. 7) are in alignment. The projections 33 are `cooperatively associated with an indexing spring I9| diagrammatically indicated in Fig. 7 and clearly shown in Fig. 3. The indexing spring has a. U-shaped bent end portion 32 locked into a slot 93 of the cover 24, The indexing spring 3| has another end portion 34 which is curved. that is, semi-circular when viewed in Fig. 3. The switch in Figs. 3 and 'I is in the olf position in which all indexing projections 33 engage the same side of the semi-circular spring spaced from the crest thereof. If now a push button other than the button 35 is pushed in. one or several slides are vertically displaced. 'I'he indexing projections of these slides during the displacement travel across ,the crest of the indexing spring, pushing the spring outward. and in their end positions are engaged by the other side of the semi-circular spring portion 34.

The several operating positions of the switch are diagrammatically shown in Figs. 8 to 12 inclusive. In Fig. 8 the button 43 is pushed in to establish a circuit in which the two coils I2 and I3 are connected in parallel to the outer conlductors 53,A 32. In this position maximum heat output is obtained. Upon pushing the button 43 in while the switch is in "ot! position, the

slides

23, 29, 33 are forced up, the pin 45 traveling along the working surfaces of the apertures 22a, 28a and 30a. If previously the button 35 was in the in" position, as in Fig. '1, this button 35 is forced outward upon upward displacement of the slide 28, the pin 45 of which travels along the working surface of the aperture 28j.

In the off position (Fig. 7) all contact blades are in opening position, each blade being forced open by engagement with a cam surface of one of the slides. Thus. the blade 63 (Fig. 7) is held open by engagement with the cam surface 88, the blade 82 is held open by engagement with cam surface 86, the blade 6| is held open by engagement with cam surface 80, the blade is held open by engagement with cam surface 89, and finally the blade 59 is held open by engagement with the cam surface 84. In the high position, with button 40 pushed in `(Fig. 8) the blade 63 has left the cam surface 88 to close the respective contacts. The blade 62 in Fig. 8 has left the cam surface 86, causing closing of the respective contacts. The blade 6I in Fig. 8 is still held open by the cam surface 80 of slide 3|. The blade G0 (Fig. 7) has left the cam surface 89 and at the same time has been engaged by the cam surface 83 and therefore the blade 60 is still in open position. The blade 59 in Fig. 8 has left the cam surface 84 and closed the respective contacts.

In Fig. 9 the push button 39 is actuated, the

slides

28 and 30 are in the up position to establish a circuit in which the heating coil I2 is connected between the outer conductors 50, 52.

In Fig. 10 the push button 38 is pushed in, the

slides

28, 29 are in the up position to establish a circuit in which both coils I2, |3 are connected in parallel between the neutral and the outer conductor 52.

In Fig. 11 the push button 31 is pushed in, the slide 28 is in the up position to establish a circuit in which the heating coil I2 is connected between the neutral and the outer conductor 52.

In Fig. 12 the push button 36 is pushed in, the

slides

28 and 3| are in the up position to establish a circuit in which the heating coils I2, I3 are connected in series between the neutral and the outer conductor 52.

The arrangement of Fig. 13 shows a push button switch |00 mounted on a kitchen range |0| having a heating unit |02 and a back-splash |03. The switch structure shown in Figs. 13 to 16 inciu-sive is described and claimed in my copending application S. N. 645,176, filed February 2, 1946, which is a division of this application and is assigned to the assignee thereof. The backsplash |03 has an opening or openings |04 through which the buttons of the switch project. In this example, as in Fig. 1, the switch is mount- Ied on the rear of the back-splash and secured thereto by means including brackets |05 and screws |06. The switch |00 has a molded insulating base pockets and closed. by a cover |09 corresponding to the base I1 and the cover 24 respectively of Fig. 4. A plurality of contact blades I|0 corresponding to the blades 59 to 63 of Fig. 2 are |01 forming a chamber with mounted-on the insulating base by means 'including hollow rivets corresponding to the rivets 89 of Fig. 2. Terminal screw means4 I Ia` are secured to sorne of therivets ||I. The contact blades IIO are actuated by four slides ||2 corresponding to the slides 28 to 3| of Fig. 4. The contact bladesy |I0carry on their free ends movable contacts I3 cooperatively associated with stationary contacts ||4 secured to the base and electrically connected' to terminal means |I5 corresponding to the terminals 41 to 40 of Fig. 2. The arrangement so far described is substantially the same as that in Fiss. 1 to l2. The four slides H2 for actuating the contact blades ||0 are cooperatively associated with six push buttons IIB for selectively establishing any one of five different circuits.

Each push button according to the modification shown in Figs. 13 to 16 comprises a plunger |I1, Fig. 16, whichis fabricated from a single piece of material, preferably sheet metal, by a punching and forming process and having a front wall H8, a rear wall ||8 and side walls |20 and |2I. The rear wall I|8, Fig. 16, has a downward or lower extension |22 forming a cylindrical pin |23 extending horizontally towards the front wall ||8 and corresponding to the pins 45 in Fig. 6 for cooperation with openings or cam surfaces |24 of the slides ||2. Upper portions of the side walls |20. |2| have extensions forming lugs |25 with openings |28. The rear wall I|9 has an upper extension with a raised bead |21 on its back projecting towards the front wall ||8. The lugs |25 and the bead |21 serve to locate and positively support a button proper |28 which has opposite side walls formed with lugs |29 shaped to fit the openings |26 of the lugs |25 and producing a snap action therewith. The button is prism-shaped and macle from translucent or transparent plastic material. The button has an outer end surface or top |30 which is slightly curved and an opposite reflecting surface or bottorn of the button. The reflecting surface I3I is preferably provided with a plurality of parallel grooves |32 to obtain best light reflection towards the end surface |30. When assembled with the plunger the button is held firmly in position by spring tension of the lugs |25 and also by additional spring pressure provided 4by the rai-sed bead |21 on the back wall engaging one end of the reflecting surface |3|, as best shown in Fig. 14. Thus,A in this arrangement the plunger is made from a single fabricated piece corresponding to the four separate elements 4|, 42. 43 and 45 in the arrangement of Fig. 6. Portions of the fabricated plunger form means for locating and supporting the plastic button and another portion of the fabricated plunger forms a horizontally extending pin for cooperation with the slides of the switch.

The pin |23 and the front wall ||8 are vertically spaced, forming a gap -for easy assembly of the slides which can be accomplished simply by hooking the slides onto-the pin.A Lower portions of the sidewalls |20, |2| have rectangular slots |33 opening towards the pin |23 to accommodate portions of the four slides |l2 when assembled therewith.

During assembly of the push buttons and the slides on the base the push buttons are inserted |34 and a reflector |35 with a miniature light bulb |36 to improve its action and give desired lighting effects on the switch buttons. The adapter is in the form of a Vfabricated sheet metal case having a top |31 and aside wall |38. The

end walls of the adapter formlugs |38 for attach- |3| inclined towards the rear and front walls ment to the insulating base by means ofscrews |36'.

The top wall |31 has six rectangular openings |40 for accommodating, guiding and aligning outer portions of the reflecting buttons |10. These openings |40 support the buttons as they are moved in and out, preventing any tilting thereof and assuring smooth movement during operation. Proper alignment of the push buttons and plunger assemblies is important for correct indexing oi the switch slides in that-it insures the actuating pins |23 being held in correct position at both extremes of travel of the push buttons.

The side wall |38 of the adapter has six windows |4| aligned and each associated with one of the openings |40 in the top. 'I'he windows are so placed that when a. push button is moved all the way in, its lower edge comes opposite a window, thus allowing light to be transmitted through the transparent material of the button and to be reflected to the outer surface |30 of the button by the obtuse angle and the grooves |32 of the reflecting surface |3 I. The proper location of the windows |4| and the shielding eilect produced by the adapter to prevent leakage of light to adjacent buttons is important to give a clear visual indication as to which of the buttons is actuated.

In addition, the adapter provides a convenient means for mounting the switch on the range switchboard as by the aforementioned brackets and screws |06. Furthermore, in the present arrangement the adapter functions as a support for the reflector |35 with the light source |34.

The reflector |35 is made from fabricated sheet metal forming lugs |42 for attachment to the side wall |38 of the adapter by means of screws |43. 'I'he reflector has plane side walls |44 and a curved, substantially cylindrically shaped reflecting rear wall |45. It has been found that such cylindrical wall provides for substantial concentration of the light towards the relatively small windows A|4|. The miniature lamp or bulb |36 is held ina socket |46 securely attached to an end portion of the reflector by means including a nut |41. The reflecting wall |45 adjacent the socket |46 is cut away, permitting removal of the socket |46 with the bulb |36 upon loosening of the nut |41 without requiring dismantling of the reflector. The free edges of the side walls .|44 of the reflector when mounted on the base are spaced from the adapter, thus forming a clearance |46, at bottom only, permitting the circulation of air through the reilector and thus assuring ventilation and reducing heating of the insulating base.

The operation 'of the switch is similar to that described above in connection with Figs. 1 to 12. The circuit of the indicating lamp |36 may be interconnected in known manner with the off button so that the lamp |36 is disconnected whenever the off button is pushed in and the lamp |36 is energized as soon as any one of the other buttons is pushed in.

Thus, with my invention I have accomplished an improved construction and arrangement of push button switches which are comparatively simpe in construction; all of the elements may be produced by simple manufacturing processes, such as molding, punching and forming operations; the switch is fool-proof. Once a push button is pushed in it is locked in position and can be moved out only upon actuation of another button. The various push buttons are interlocked through their pin engagements with the various,

slides making it impossible simultaneously to complete the actuation cf more than one button. actuation oi'v the push buttons requires small force only due to the small frictional resistance between the slides and also between each slide and the casing. The slides are practically iioating in the chamber of the base. The end positions of the slides are nxed by the indexing arrangement which also aids to produce a snap action for the different operating positions.

Having described the-method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other metas.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A push button switch comprising a bue forming a chamber, contact means including a plurality of contact switch actuating members supported in the chamber, and means for actuating said members, said means including a plurality of slides disposed in the chamber, each slide having an edge with a plurality of spaced cam surfaces adapted in certain longitudinal positions of the slides to actuate certain of said members and each slide having a plurality of apertures, each of which is provided with an actuating surface, and a plurality of push buttons projecting into the chamber and each having a pin projecting through an aperture of each slide, said actuating surfaces of said apertures being engageable selectively by said pins so that the associated slides are operated to preselected longitudinal switch controlling positions by said push buttons when depressed.

2. A push button switch comprising a base forming la chamber, contact means including stationary contacts secured to the chamber and movable contacts cooperatively associated with the stationary contacts and a plurality of springs secured to the casing and supporting the movable contacts, a plurality of slides disposed within the chamber, each slide having an edge with a pair of projections engaging a wall of the casing to support the slide and other projections for engaging certain of the springs to eifect opening of the respective contacts in certain longitudinal positions of said slides, and each slide having a plurality of apertures with diagonal working surfaces, and means for actuating the slides including a plurality of push buttons projecting into the chamber and each having a pin projecting through an aperture of each slide, and positioned to engage selected ones of said diagonal surfaces when the buttons are selectively depressed so as to actuate said slides to prede- 1termined longitudinal contact controlling posiions.

3. A push button switch comprising a base forming a chamber, contact means including stationary buttons secured to the chamber, movable buttons cooperatively associated with the stationary buttons and a plurality of parallel springs secured to the casing and supporting the movable buttons, a plurality of slides disposed within the chamber, each slide having an edge with a pair of projections engaging a wall of the casing and other projections for engaging certain of the springs to effect opening of the respective contacts in certain operating positions of the slides and each slide having a plurality of apertures with diagonal working surfaces, means for actuating the slides including a plurality of Push buttons projecting into the chamber and lng a pin projecting through an aperture o! each slide and positioned to engage certain of said working surfaces to operate the slides to selected operating positions, and means to reduce frictional resistance between the slides including a plurality of bosses between adjacent slides and secured to one of them.

4. A push button switch comprising a base forming a chamber, contact means including stationary buttons secured to the chamber, movable buttons cooperatively associated with the stationary contacts and a plurality of springs secured to the casing and supporting the movable buttons, a. plurality of slides disposed within the chamber, each slide having an edge with projections for engaging certain of the springs to eifectbpening of the respective contacts in predetermined operating position of the slides and each slide having a row of apertures with inclined working surfaces, means for actuating the slides including a plurality of push buttons projecting into the chamber and each having a. pin projecting through an aperture of each slide, said pins selectively engaging said Working surfaces when said buttons are depressed selectively so as to operate said slides to said predetermined controlling positions in a predetermined sequence, and indexing means for ilxing the end positions of the slides and producing a snap action upon actuation of the switch.

5. A push button switch comprising a base forming a chamber, contact means including stationary buttons secured to the chamber and movable buttons cooperatively associated with the stationary buttons and a plurality of springs secured to the casing and supporting the movable buttons, a plurality of Slides disposed within the chamber, each slide having an edge with projections for engaging certain of the springs to effect opening of the respective contacts in certain operating positions of the slides and each slide having s, plurality of apertures with diagonal Working surfaces, means for actuating the slides to effect relative movement between them including a plurality of push buttons projecting into the chamber each push button straddling the slides and having a pin projecting through an aperture of each slide and engageable with selected ones of said working surfaces as the buttons are depressed so as to actuate the associated slides to certain operating positions, and indexing means for iixlng the end positions of the slides and producing a snap action upon actuation of the switch, said indexing means including a projection on each slide and a spring supported on the casing and engaging the projections.

6. A push button switch comprising a base forming a chamber, contact means including stationary contacts secured to the chamber and a plurality of parallel springs each having an end portion secured to the casing and another end portion opposite the stationary contacts, a plurality of slides disposed within the chamber, each slide having an edge with a pair of projections engaging a wall of the casing and other projections for engaging certain of the springs to actuate the respective contacts in certain operating positions of the slides and each slide having a plurality of apertures with diagonal working surfaces, means for actuating the slides including a plurality of Push buttons each having a pin projecting through an aperture of each slide and engageable with selected ones of said working surfaces as the button is depressed s as to 0P- each slide engaging in one position of the slideerate the associated slides to certain of said operating positions, and indexing means for fixing the end positions of the slides and producing a snap action upon actuation of the switch including a projection on each of said edges and a spring held on the casing and having a curved end portion forming a crest and engaging said indexing projections, the indexing projection of said curved spring portion to one side of the crest and in the other position of the slide to the other side of the crest.

7. A push button switch comprising a base forming a chamber with a row of pockets having aligned openings, contact means including a plurality of contact springs supported on the base, means for actuating the springs comprising a plurality of slides disposed in the chamber and extending through the aligned openings of the pockets, each slide having projections for actuating certain sprlngs in certain operating positions and each slide having a plurality of apertures in the shape of substantially rectangular triangles with rounded corners, and push buttons for actuating the slides, each projecting into and being guided in a pocket and having a pin extending through an aperture in all of the slides and engageable with selected ones of the hypotenuses of said triangles to operate the associated slides to said positions in a predetermined sequence as the buttons are depressed.

8. A push button switch comprising a base forming a chamber with a row of pockets having aligned openings, contact means including a. plurality of contact springs supported on the base, means for actuating the springs comprising a plurality of slides disposed in the chamber and extending through the aligned openings of the pockets, each slide having projections for actuating certain springs in certain operating positions and each slide having a plurality of apertures in the shape of substantially rectangular triangles with rounded corners, and push buttons for actuating the slides, each projecting into an opening and having a pin extending through apertures in the slides and engageable with selected ones of the hypotenuses of the triangles to operate said slides selectively to said positions as the buttons are depressed, and means for locking each push button in one of its end positions comprising an ear formed on a side of one of the rectangular triangles cooperatively associated with the pin of such button.

9. A push button switch comprising an insulating base, contact means supported on the base, means including a plurality of push buttons slidable on the base for actuating the contact means and projecting outwardly from the base, and an adapter secured to the base and having a wall spaced outwardly from the base and provided with openings slidably receiving the outer ends of said push buttons so as to guide and support them.

10. In a switch, a base having a recess with lateral extensions, a ilexible contact blade with lateral extensions iitting the aforementioned extensions accurately to position the blade on said base, the blade having an end portion curved towards the base and projecting into a depression thereof, and electrical conducting means securing the blade to the base near the curved portion and biasing the curved portion into the depression to maintain good electrical contact upon loosening of the securing means and shrinking of the insulating base.,

il 11. In n switch, a. bqnnliiexiblo oonttct bilde hnvingnfreeendwithaoontncttheroonsnd another end with a curved portion, nid bue having s depression for receiving the curved por-- Tnei'ollowing refereneeamofrooordintno nieoithispstent:

tion, und a rivet securing the other ond near the l Number UNITED STATES PATENTE Nuno Dnto Hall Mu'. 1l, 1941 Mone; Aug. 14, 1945 Bergmann lnx. 1l. 1041 Probergor Jul: 15, 1224