Keyboard Switch

Abstract

A low profile pushbutton switch has a button telescopically mounted on the base. A contact having a plurality of arms is positioned between the button and the base, with one group of arms being disposed to make contact with terminals within the base and another group of arms being positioned to receive the actuating force from the button.

Description

SUMMARY OF THE INVENTION

The present invention relates to pushbutton switches and in particular to a simply constructed reliably operable pushbutton switch having a low profile.

Another purpose is a pushbutton switch of the type described in which the contact has a plurality of arms, a portion of said arms being used to make electrical contact between terminals and another portion of said arms performing an actuating function.

Another purpose is a pushbutton switch of the type described in which the button return spring maintains the contact in an open position relative to the terminals.

Another purpose is a pushbutton switch of the type described in which the telescopically mounted button has means for maintaining alignment and position of the return spring.

Another purpose is a pushbutton switch of the type described including a telescopically mounted button and base in which each member has cooperating flanges forming a resilient stop for the button.

Other purposes will appear in the ensuing specification, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated diagrammatically in the following drawings wherein:

FIG. 1 is a top plan view of a switch of the type described,

FIG. 2 is a side view of the switch of FIG. 1,

FIG. 3 is a bottom view of the switch of FIGS. 1 and 2,

FIG. 4 is an enlarged section along plane 4--4 of FIG. 1,

FIG. 5 is a section along plane 5--5 of FIG. 4,

FIG. 6 is a top view of the switch base,

FIG. 7 is an end view of FIG. 6,

FIG. 8 is a top view of the switch button, with the indicia removed,

FIG. 9 is a bottom view of the switch button,

FIG. 10 is a section along plane 10--10 of FIG. 9,

FIG. 11 is a section along plane 11--11 of FIG. 9,

FIG. 12 is a top plan view of a modified switch button, with the indicia removed,

FIG. 13 is a top plan view of the indicia for FIG. 12; and

FIG. 14 is a section along plane 14--14 of FIG. 12 with the indicia of FIG. 13 added.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a pushbutton switch of the type commonly used in keyboards. Of particular advantage is the fact that the button may be quickly and simply assembled, with a minimum of tooling, and when assembled has an exceptionally low profile. The outside dimensions of the switch button may be as small as 3/8-inch per side.

A switch button is indicated generally at 10 and is telescopically mounted on a switch base 12. A pair of terminals 14 and 16 extend outwardly from the base 12 and are positioned in bores 18 formed within the base. Each of the terminals 14 and 16 have an interior portion or contact portion indicated at 20 and 22, respectively.

Positioned within a well 24 in base 12 is a coil spring 26. The upper end of coil spring 26 is positioned against a cross-shaped contact member 28, shown particularly in FIG. 5.

Contact 28 has a plurality of arms, in this case four, although the invention should not be limited to this precise number or disposition of arms. Arms 30 and 32, as particularly shown in FIG. 5, are disposed above terminal portions 20 and 22, and are arranged for closing contact therewith. Contact arms 34 and 36 are disposed for actuation by the switch button, as will be described hereinafter.

Looking particularly at FIG. 6, the four sides of the generally square-shaped base each have a centrally located groove 38. The grooves 38 receive mating rails 40, formed on the inside of the button walls as illustrated in FIG. 9, to properly align the button on the base. Integral with the rails 40 and extending generally inwardly and downwardly therefrom are projections or hooks 42 which, as shown in FIG. 4, extend within the coil spring 26 to maintain alignment of the spring within the switch. There are four such projections as there are four rails, although the invention should not be limited to this particular configuration. In like manner, obviously the switch should not be limited to a square-shaped configuration.

The base 12 has diammetrically opposed recessed areas 43 which contain the inner portions 20 and 22 of the terminals 14 and 16. In like manner, there are oppositely-disposed recessed portions 44 on the other corners of the base, which recessed corners will receive the spring arms 34 and 36 when the button is depressed downwardly upon the base.

The base 12 may have a pair of outwardly-directed flanges 46, shown particularly in FIGS. 6 and 7, which extend outwardly from diammetrically opposed corners in the area of the recesses 44. In like manner, the lower surface of the button 10 has inwardly-directed flanges 48 (FIG. 10) which cooperate with the outwardly-directed flanges 46 on the base to hold the button and base together. In assembly, the button is pushed downwardly upon the base until the flanges 48 pass beneath the flanges 46 of the base, thus the base and button are held together and the outward travel of the button relative to the base is limited by the stops. Since in many applications the button and base may be formed of a conventional plastic having a certain degree of resilience, the mating flanges 46 and 48 provide a resilient stop cushioning the return of the button to the unoperated position of FIG. 1.

The button 10 has actuating portions 50 at opposite corners thereof, which portions are positioned to contact the contact arms 34 and 36 to effect operation of the switch.

The button 10 may have a well 52 formed in the upper surface thereof, which well receives a suitable indicia member 54 illustrated in FIGS. 4 and 10. The indicia member may take on a number of different forms, as what is important is to provide a visual indication of a number or character at the upper surface of the button.

The structure of FIGS. 12, 13 and 14 is basically the same switch as shown in FIGS. 1-11, with the exception of modifications to the button in the area of the indicia. The button 56 has a well 58 at the upper end thereof and an indicia member 60 is positioned within the well. The indicia member 60 has two inwardlydirected circular posts 62 which fit within openings 64 in the button. A heat seal or some other fastening means may be used to secure the indicia member to the button. The indicia itself, indicated at 66 in FIG. 13, is embedded within the transparent or opaque portion 68 of the indicia member 60. In the alternative, it may be at the interface between the transparent portion 68 and an opaque lower portion 70. The indicia member in the structure of FIGS. 1-11 may include a character or number embedded within a transparent plastic member or it may include a character painted or otherwise affixed to one side or the other of the indicia member 54.

In operation, when the button is depressed, the activating portion 50 will push downwardly upon the oppositely-directed contact arms 34 and 36, forcing the contact member 28 toward the terminals 14 and 16. Arms 30 and 32 of the contact member will contact the terminal portions 20 and 22 to complete the electrical connection therebetween. The return spring 26 not only maintains the button in spaced relation to the base, as shown in FIG. 4, but also maintains the position of the contact 26 against the button, thus returning the contact to an open position. The projections 42 of the button are effective to maintain alignment of the coil spring 26 within the well of the base.

The resilient stop formed by the cooperative flanges 46 and 48 serves to cushion the return of the button to its full out position of FIG. 4, thus minimizing any noise attendant to switch operation.

No special tools are needed to assemble the button on the base or to position the various parts within the base. The switch is rugged, compact, simply constructed and reliably operable.

Although the switch is shown in a generally square construction, obviously other forms or configurations are equally satisfactory. The switch, for example, may be rectangular, eliptical or round and still maintain the basic components of the invention.

Of particular advantage is the cross-shaped contact or the contact having a plurality of outwardly-directed arms. Two of the arms receive actuating power from the button moving the other two arms into a position to make electrical and mechanical contact with the terminals.

Whereas the preferred form of the invention has been shown and described herein, it should be realized that there may be many modifications, substitutions or alterations thereto.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pushbutton switch including a base and a button telescopically mounted on the base, spaced terminals extending outwardly from the base and having portions positioned within the base, spring means normally biasing the button away from the base,

a contact having a plurality of outwardly extending substantially coplanar arms positioned between the base and button, certain of said arms being disposed for contact with said terminal portions, the remaining arms being disposed for contact by said button, means on the button for contacting said remaining arms to move said certain arms into contact with said terminal portions.

2. The structure of claim 1 further characterized in that said contact arms are generally uniformly spaced, one from another.

3. The structure of claim 2 further characterized in that said arms are generally equally spaced, one from another.

4. The structure of claim 3 further characterized in that said arms are spaced on the order of about 90.degree. apart.

5. The structure of claim 2 further characterized in that said certain contact arms are diammetrically aligned.

6. The structure of claim 5 further characterized in that each remaining contact arm is positioned between adjacent certain contact arms.

7. The structure of claim 1 further characterized in that said spring means includes a coil spring seated upon said base.

8. The structure of claim 7 further characterized by and including means on said button projecting toward the base for maintaining alignment of said spring.

9. The structure of claim 8 further characterized in that said alignment means projects into said spring.

10. The structure of claim 1 further characterized by and including cooperating means on the base and button for maintaining alignment between the base and button during telescopic movement of the button.

11. The structure of claim 10 further characterized in that said alignment means includes a plurality of grooves on said base and a plurality of inwardly-extending rails on the button mating with said grooves.

12. The structure of claim 11 further characterized by and including means on the button, integral with said rails, for maintaining alignment of said spring means.

13. The structure of claim 1 further characterized by and including a stop limiting movement between the button and base.

14. The structure of claim 13 further characterized in that said stop includes at least one outwardly-directed flange on the base, and at least one cooperating inwardly-directed flange on the button.

15. The structure of claim 13 further characterized in that said stop is resilient.

16. The structure of claim 1 further characterized by and including indicia means mounted on the outer face of the button.

17. The structure of claim 1 further characterized in that said spring means urges said contact toward said button.

18. The structure of claim 17 further characterized in that said spring means includes a coil spring bottomed on the base with the opposite end of the spring being positioned against said contact.