Dual slide three-position switch

An improved switch includes two moving contact members which move in parallel planes. The switch may be moved to either of two positions to complete either of two circuits. The contact members are normally biased to a central neutral position. Since the contact members move in a plane, rather than pivoting on a yoke, there is greater tolerance in positioning the moving contact members.

BACKGROUND OF THE INVENTION 
This invention relates to a switch that moves between three positions to 
complete two distinct circuits, wherein the moving contact members move 
linearly. 
A known three-position switch is utilized to provide switch actuation for 
two distinct circuits, along with a "home" or neutral position. This type 
of switch is widely utilized in applications for controlling movement of 
an element in opposed directions. As one common example, a switch for 
moving a seat rearwardly or forwardly typically has a central neutral 
position at which the seat does not move. The switch can be actuated in 
one direction to move the seat forward, and in the opposite direction to 
move the seat rearwardly. 
Typically, the known three position switches rely upon a rocking yoke 
carrying a pair of contacts. The rocking yoke is typically biased to a 
central neutral position at which the contacts are maintained out of 
contact with corresponding contact plates. An operator may move the 
rocking yoke against the bias force to either of two extreme positions at 
which the contacts do contact a contact plate, completing a circuit. In 
this way, the operator can control the movement of an element, such as a 
seat. 
The yoke switch does have certain deficiencies. In particular, the height 
of the yoke and contacts relative to the contact plates must be carefully 
controlled. If the heights are not carefully controlled, then the contacts 
may not make good contact with the contact plates. This presents 
challenges to the designer and assembler of the switches. 
SUMMARY OF THE INVENTION 
In a disclosed embodiment of this invention, a switch moves between 
positions for completing two distinct circuits, and to a central neutral 
position. Moving contact members move linearly, and in a parallel plane 
between the two "actuation" positions. In a preferred embodiment of this 
invention, opposed contact plates are defined at two ends of the switch 
housing. When the contact plates are contacted by a moving switch contact, 
one of two circuits is completed. 
This type of switch may be preferably utilized for controlling a moving 
element such as a seat. When one of the two circuits is complete, the seat 
is moved forwardly, and when the other is complete, the seat is moved 
rearwardly. The switch is biased to the neutral position at which the seat 
is not moved. 
In a preferred embodiment of this invention, the switch is grounded when in 
the neutral position. The housing preferably includes ground plates at 
locations spaced from each other by a first axial distance. The housing 
further includes actuation contact plates for each of the two circuits 
which are spaced beyond the ground plates. 
A central actuation post can move either of the moving contact members to 
complete either of the two circuits. Springs bias the two moving contact 
members to the central neutral position. The moving actuation post may 
overcome the spring force and move one of the two moving contact members 
to complete its respective circuit. 
In preferred embodiments of this invention, the moving contact members have 
opposed interfitting fingers and slots. Each of the contact members has 
one finger received between slots on the other component. The slots are on 
a side of the contact members adjacent the actuation contact plate for the 
other contact member. A spring is preferably mounted between each finger 
and the post. The opposed springs bias the two contact members to the 
neutral position. 
The actuation post may move either contact member to complete its circuit. 
Arms from the post are guided in guide slots in both contact members, thus 
ensuring linear parallel movement of the contact members. 
In one main feature of this invention, the contacts which move with the 
moving contact members are formed in a plane which is perpendicular to the 
direction of movement of the moving contact members. In this way, the 
contacts are brought into facial contact with a contact plate in the 
plane. This is an improvement over the prior art pivoting movement, and 
requires less precise positioning of the contact members than the prior 
art pivoting or yoke type three-position switch.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
An improved switch 20 is illustrated in FIG. 1. A switch housing 22 
includes guide floor 23 for guiding moving members as will be explained 
below. An actuation post 24 is received between two relatively moving 
contact members 25. Each contact member 25 has a finger 26 at one end 
guided between slots 27 from the other member. The actuation post 24 may 
receive a cover plate 28 including a slot 29 for allowing the post 24 to 
pivot. 
A pair of ground plates 30 are received within housing 22 and grounded. A 
first actuation contact plate 32 is shown leading to a wire 33. A first 
circuit is completed by contact between plate 32 and a contact member 25. 
Similarly, a second actuation contact plate 34 communicates with a wire 35 
to complete a second circuit when contacted by a moving contact member. As 
shown, moving contact members 25 each include electrical contacts at both 
axial ends. At one axial end, a ground contact 36 selectively contacts a 
ground plate 30. An actuation contact 38 selectively contacts one of the 
actuation contact plates 32 or 34. In the position shown in FIG. 1, only 
one contact can be seen on each moving contact member 25. It should be 
understood, that the contact member 25 with the ground contact 36 at the 
illustrated end in FIG. 1 has an actuation contact 38 at its opposed end. 
Similarly, the contact member 25 having the illustrated actuation contact 
38 has a ground contact 36 at its non-illustrated end. 
As shown, the contacts 36 and 38 are formed on ends of the moving contact 
members 25, and are found in a plane which is perpendicular to the 
direction of movement of the moving contact members 25. Thus, these 
contacts are brought into facial contact with the planar contact plates 
30, 32, 34. Less precise positioning of the switch components is thus 
required than was the case with the prior art pivoting yoke-type three 
position switches. 
As shown in FIG. 2, each contact member 25 has a guide slot 40 receiving an 
arm 42 from the actuation post 24. Arms 42 allow the two contact members 
25 to move relative to the post 24, and each other, during actuation of 
the circuits. As shown, the slots 40 are elongated and extend for a 
greater distance than the arms 42. Arms 42 can thus move with the guide 
slots 40, and ensure the movement of the contact members 25 is linear and 
parallel to a common central plane. 
Springs 44 fit into cylindrical spring receiving spaces 46 in each finger 
26. Each spring 44 provides a bias force between a cylindrical spring seat 
48 in post 24 and the finger 26. Each contact member 25 includes an 
abutment face 49 that is contacted by knob 24 when it is being driven to 
actuate its respective circuit. 
As shown in FIG. 3, the switch is in a neutral position. The springs 44 
bias fingers 26, and hence contact members 25, into positions at which the 
ground contacts 36 contact the ground plates 30. As shown, the ground 
plates 30 are spaced by a first axial distance, while the actuation plates 
32 and 34 are spaced outwardly of the ground plates 30. In this position, 
the abutment faces 49 are both biased against the actuation knob 24. The 
switch is held at this neutral position unless an actuation force is 
applied to knob 24. 
As shown in FIG. 4A, the actuation knob 24 has now been driven upwardly as 
shown in the figure. Knob 24 forces abutment face 49 on the left-most 
contact member 25 upwardly. Actuation contact 38 now contacts actuation 
plate 32. A first circuit is now completed. As shown, the spring 44 
received on the right-most contact member 25 is compressed. The right 
contact member 25 is thus held securely, with ground contact 36 held 
against ground plate 30. 
The movement is reversed in FIG. 4B. Now, actuation contact 38 is held 
against actuation plate 34. The second circuit is completed in this 
position. When the force is released from the actuation knob 24, the 
contact members return to the position shown in FIG. 3. 
FIG. 5 is a cross-sectional view along the center line of springs 44 and 
actuation knob 24. As shown, each finger 26 includes a cylindrical pocket 
46. The springs 44 are received between cylindrical pocket 46 and a pocket 
48 in actuation knob 24. As shown, arms 42 extend through guide slots 40. 
The linear movement of the moving contact member brings the actuation 
contacts into contact with an actuation plate in a plane which is 
perpendicular to the linear direction of movement of the moving contact 
member 25. In this way, the tight tolerances that were set for the known 
rocker or yoke-type three position switches are no longer necessary. The 
present invention thus simplifies the assembly of a three-position switch 
when compared to prior art yoke-type three-position switches. 
A preferred embodiment of this invention has been disclosed, however, a 
worker of ordinary skill in the art would recognize that certain 
modifications would come within the scope of this invention. For that 
reason, the following claims should be studied to determine the true scope 
and content of this invention.