Precisely aligned switch actuator assembly for multiple switches

An electrical switch actuator mechanism which has an accurately aligned position. The actuator operates printed circuit board pushbutton switches by depressing a spring finger to operate each pushbutton. Each of the fingers has a raised land with a precisely angled slope which a rub bar on the back of the actuator handle rides upon to depress the spring. However, the angled slope and the spring action of the leaf spring also act backward against the rub bar to precisely locate the position of the actuator handle so that a group of such switches are properly aligned when the switches are in the same position.

SUMMARY OF THE INVENTION 
This invention deals generally with electrical switch actuators and more 
specificaly with a switch actuator meant to be one of several side by side 
units which are precisely aligned when they are in one position. 
An often neglected aspect of switch design is the precision of the location 
of the neutral position of the switch. This is not surprising since when a 
switch is mounted in an isolated location, small variations in the 
location of the one position, either after each operation of a switch or 
when one switch is replaced with another, have no effect on the operation 
of the switch and are likely not to be noticeable even if someone were 
looking for them. 
However, if two or more switches are installed side by side, in a manner so 
that their actuators are to form a straight line, any variations in 
positions between switches are quite obvious. In such an arrangement, the 
play in the positions of the several switches detracts from the aesthetic 
appearance which led to the linear arrangement of the switches in the 
first place. In actual fact, a typical linear arrangement of multiple 
switches rarely looks like it is aligned since the play in the neutral 
position of each switch never allows all the switch actuators to be in 
line. 
The present invention eliminates the above mentioned prior art problem. It 
offers an easily manufactured, economical switch with a precisely located 
neutral position and positive switch action in both directions from the 
neutral position. In the present invention the electrical contact function 
and detect function are separated, and the separation permits the detent 
function to be designed for precise location of the actuator. 
The switch actuator of the present invention contains a keycap, the 
actuator part which is manually moved, with a rub bar on the backside of 
the keycap, inside the switch body. The rub bar is a narrow plastic part 
with rounded corners, with its backside approximately a half cylinder. 
The rub bar acts on spring fingers each of which is anchored only at one 
end, has a spring action which pushes it toward the rub bar, and has a 
sloped bend in the direction of the rub bar near the end opposite its 
anchored end. Thus, as the rub bar is moved away from the anchored end of 
the leaf spring it rides up one slope of the bend and forces the leaf 
spring to deflect away from the rub bar. When the plateau of the bend in 
the leaf spring contacts the rub bar the maximum spring deflection is 
obtained. It is a leaf spring extension on the far side of the plateau 
which is used to accomplish the electrical action of the switch. The 
extension of the leaf spring is located above and aligned with the 
actuator of a conventional miniature push button switch. When the rub bar 
deflects the leaf spring as it moves up the slope of the bend, the leaf 
spring extension moves toward and activates the push button switch. Thus, 
the motion of the keycap is converted into an action that activates the 
push button switch. 
In the preferred embodiment of the invention, a second leaf spring oriented 
in the opposite direction from the first operates in the same manner as 
the first lead spring, and keycap sliding motion in either direction 
therefore activates one or the other switch. The neutral position of the 
switch actuator is that position in which the rub bar has not moved in 
either direction suffciently to move up either leaf spring's slope 
sufficiently to deflect the spring significantly. It is the interaction of 
the two leaf springs and the rub bar which give the switch actuator 
mechanism its center-off detent and its highly accurate location. 
The particular shape and angle of the slope of the bend in the leaf spring 
is what moves and holds the combined rub bar and keycap assembly at its 
precise neutral location. When the two oppositely oriented leaf springs 
are located so that they each just touch the rub bar with their sloped 
portion, the rub bar is held in a precisely repeatable neutral location 
with no play no permit variation. Moreover, in the preferred embodiment 
the angle of the sloped portion of each leaf spring is selected so that 
the spring will actually drive the rub bar back to the neutral position. 
It is therefore practical to install several such switches side by side 
with the assurance that all their keycaps will be in alignment when the 
switches are in the neutral position.

DETAILED DESCRIPTION OF THE INVENTION 
The preferred embodiment of the invention is shown in FIG. 1 which is a 
simplified internal view of switch actuator assembly 10. Only one of two 
spring fingers 12 is shown in the embodiment in FIG. 1 which depicts a 
two-position switch. The interaction of spring finger 12 and rub bar 14 
can also be shown more clearly in a single spring finger embodiment. 
Switch actuator assembly 10 is attached to circuit board 16 and switch body 
18 by conventional attachment methods well known in the art, such as hook 
attachment 20. Similarly, circuit board pushbutton switch 22 is a 
conventional switch and its attachment to circuit board 16 is 
conventional. Switch 22 is aligned with extension 21 of spring finger 12. 
The present invention departs from conventional design in the structure and 
function of keycap 24, rub bar 14 and spring finger 12. Spring finger 12 
is part of a larger assembly, as shown in FIG. 3, and is used to 
accurately locate one position of keycap 24. 
Keycap 24 and rub bar 14 are parts of a single handle assembly 26 which 
slides (vertically in FIG. 1) in track 28. As keycap 24 is moved within 
track 28 rub bar 14 acts upon spring finger 12 which, in turn, pushes down 
upon pushbutton switch 22. 
This action occurs because spring finger 12, as shown in FIGS. 1, 2 and 3 
has an angularly shaped bend 30 which protrudes in the direction of rub 
bar 14. Therefore, as rub bar 14 is pushed against the slope of bend 30, 
it forces spring finger 12 to deflect away from rub bar 14 and against 
switch 22 to activate switch 22 by pressing its pushbutton 23 with 
extension 21. 
The position of spring finger 12, rub bar 14 and pushbutton 23 for 
actuation of switch 22 is shown in FIG. 1 by dashed lines. When rub bar 14 
rides up on plateau 32 of spring finger 16, it comes to rest and thereby 
locks switch 22 into the depressed position. 
The configuration of bend 30 also performs another vital function in the 
present invention. The slope of bend 30 creates a force which acts back 
against rub bar 14 to push handle assembly 26 and keycap 24 back into its 
neutral position. It is this reaction force from the spring finger acting 
in opposite directions which accurately positions keycap 24 in its neutral 
position. 
As rub bar 14 is forced back to the position shown in FIG. 1 by the slope 
of bend 30, handle assembly 26 hits against stop 27 and accurately 
positions the off position of switch actuator assembly 10. 
FIG. 2 shows only the rub bar and spring finger interaction for an 
alternate embodiment of the invention, a toggle switch which has three 
positions, with its neutral position between two switch activating 
positions. In FIG. 2, keycap 34 pivots on pivot point 35 causing rub bar 
36 to move in an arc and ride up on either bend 38 of spring finger 40 
which is attached to the switch body at end 41 or bend 42 of spring finger 
44 which is attached to the switch body at end 45. The radius of movement 
of rub bar 36 is large enough so that rub bar 36 can also rest atop 
plateaus 46 and 48. 
As shown in FIG. 2, rub bar 36, when in its neutral position, is actually 
trapped between bend 38 of spring finger 40 and oppositely acting bend 42 
of spring finger 44. The reaction forces from both bend 38 and bend 42 
push rub bar 36 into a highly accurate repeatable position so that even if 
the operator's actuating force on keycap 34 is removed when rub bar 36 is 
not in its neutral position, as long as rub bar 36 is on either bend 38 or 
42, the rest position of rub bar 36 will be accurately repeatable. 
Computations of these reaction forces, taking into account the spring force 
of spring fingers 40 and 44, the friction between rub bar 36 and bends 38 
and 42, an the friction between keycap 34 and pivot point 35 indicate that 
the range of the angle A (FIG. 2) between the bend slope and the initial 
plane of movement of the rub bar must be between 100 and 150 degrees. 
Within the expected range of coefficients of friction, this range of 
angles will assure that the reaction force against rub bar 36 is 
sufficient to return it to its precise neutral position. 
The precision of the neutral position for a group of adjacent switches 
will, of course, also be determined by the precision of the relationship 
between adjacent sets of spring fingers. This is accomplished, as shwon in 
FIG. 3, by constructing all the spring fingers of one group of switch 
actuator assemblies as a single spring finger assembly. When adjacent 
spring finger sets are formed as a single assembly, no inaccuracies can 
occur from assembly tolerances. Moreover, when the multiple spring finger 
assembly of FIG. 3 is formed by precisely machined dies, the accuracy of 
the parts is particularly high. 
The present invention is therefore able to furnish a readily manufacured, 
economical, switch actuator assembly for multiple switch groups which not 
only operates well in its electrical function, but also furnishes precise 
alignment of the switch keycaps for a pleasing appearance. 
It is to be understood that the form of this invention as shown is merely a 
preferred embodiment. Various changes may be made in function and 
arrangement of parts; equivalent means may be substituted for those 
illustrated and described; and certain features may be used independently 
from others without departing from the spirit and scope of the invention 
as defined in the following claims. 
For instance, the far side of the bend in spring finger 12 need not 
complete a trapezoidal shape, or, indeed even exist. The interaction of 
spring finger 12 and rub bar 14 requires only a bend withone slope 30, the 
one which touches the rub bar, and plateau 32 to form a locked-in position 
if that is desired.