Abstract:
A lever operated switch employs an actuating surface and a plurality of tactile switches to generate electrical states corresponding to distinct angular orientations of the lever. The lever extends from a cam having an actuating surface configured to change the state of one switch when the lever is moved between adjacent positions. The cam is reversible, permitting the switch to be mounted on opposite sides of a support with the same lever movement and switch actuation.

Description:
BACKGROUND 
   The application relates to a lever actuated switch assembly for generating multiple output states and, more particularly, to a lever actuated switch assembly in which a PC board forms part of the switch structure. 
   Lever switches that translate discrete positions of a lever into varying electrical contact states are known. Such switches can include complicated mechanical assemblies and may be expensive and unreliable. One use environment for such switches is on a control head in an emergency vehicle, where the switch actuates emergency warning devices such as signaling lights and sirens. Such switches are subject to long-term rough use under a wide range of environmental conditions. In this use environment, the several positions of the switch lever corresponding to different electrical states must be positively indicated to the user and stable when subjected to vibration and shock. 
   An objective of the present application is to disclose an improved lever switch having increased durability and lower cost of manufacture. 
   SUMMARY 
   The present disclosure relates to a lever switch that uses a rigid, planar support such as a PC board to define and maintain physical relationships between the actuating surface of a lever operated cam and a plurality of switches. The disclosed lever switch employs standard hardware and switch components in combination with two custom engineered components to provide a switch of reduced cost and improved functionality. In an exemplary embodiment, a lever-operated actuator assembly translates four lever positions into four output electrical states. The disclosed design permits selection of switch components suitable for producing the outputs and/or delivering power to loads for a particular application, rather than being limited to the electrical configuration of a self-contained assembly. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of an embodiment of the disclosed lever switch mounted to a PC board; 
       FIG. 2  is a perspective view of an embodiment of a lever according to aspects of the present invention; 
       FIG. 3  is an exploded perspective view of the actuator assembly of the switch of  FIG. 1 ; 
       FIG. 4  is a perspective assembled view of the actuator assembly of  FIG. 3 ; 
       FIG. 5  is a geometric view of the base, lever and switch components of  FIG. 2 , showing the angular relationships among the components and lever positions; 
       FIG. 6  is a bottom view of the base, lever and switch components of the switch of  FIG. 1 , showing the respective relationships of the components in a first lever position; 
       FIG. 7  is a bottom view of the base, lever and switch components of the switch of  FIG. 1 , showing the relative positions of the components in a second lever position; 
       FIG. 8  is a bottom view of the base, lever and switch components of the switch of  FIG. 1 , showing the respective positions of the components in a third lever position; 
       FIG. 9  is a bottom view of the base, lever and switch components of the switch of  FIG. 1 , showing the relative positions of the components in a fourth lever position; and 
       FIG. 10  is a perspective view of a representative installation of the disclosed embodiment of an actuator assembly mounted with respect to a PC board. 
   

   DETAILED DESCRIPTION 
   An embodiment of the disclosed lever switch will be described with respect to  FIGS. 1-10 , wherein like numerals represent like elements. The lever switch  10  includes an actuator assembly  12  and two switches  14 ,  16  mounted to a PC board  18 . The actuator assembly  12  supports the actuating surface  20  of a lever  22  in a position to change the state of switches  14 ,  16 , as shown in FIGS.  1  and  5 - 9 . The actuator assembly  12  defines four distinct lever positions, which the switches  14 ,  16  and the actuating surface  20  of the lever  22  translate into four electrical states for use as inputs to a control circuit. 
   The components of the actuator assembly  12  are shown in  FIG. 3 . In the illustrated embodiment, 8 of the 11 components of the actuator assembly  12  are standard hardware items. The engineered components of the actuator assembly are the base  21  and the lever  22 . A fastener  23  maintains the components in their functional relationships and provides a means for attaching the actuator assembly  12  to the PC board via a nut  13  as shown in  FIGS. 1 and 10 . 
   The lever  22  includes a radially projecting arm  24  having a distal end  26  at which an operator control knob may be attached, as shown in  FIG. 1 . The actuating surface  20  of the lever  22  is opposite the arm  24  and includes two radially projecting lobes  28 ,  30 . As best shown in  FIGS. 6-9 , the position of the lobes  28 ,  30  with respect to the arm  24  is not symmetrical. This arrangement places the lobes  28 ,  30  in a position to provide the desired actuation of switches  14 ,  16  in the four lever positions, as will be described in greater detail below. 
   The base  21  includes four legs  32  to support the actuator assembly at a height where the actuating surface  20  of the lever  22  is positioned to cooperate with the selected switches  14 ,  16 . The upper surface of the base defines two arcuate arrangements of depressions, or holes  34 . The center of the base defines an opening  36  for receiving the fastener  23  and includes a collar or shaft  38  about which the lever  22  will rotate. The center of the fastener opening  36  therefore defines an axis of rotation A R  for the lever  22 . The arcuate arrangements of holes  34  are concentric with the fastener opening  36 . A lateral projection  40  on each leg  32  of the base  21  supports the base at a predefined height above the PC board when the legs  32  are received in holes in the PC board as shown in  FIG. 1 . 
   The lever  22  has a central opening  42  for receiving the shaft  38  projecting from the base  21 . The lever  22  also includes two diametrically opposed openings  44  for retaining ball bearings  46 . The lever arm  24  will typically project through a slot shaped opening in a housing or face plate (not shown) of a control head mounted in the passenger cabin of an emergency vehicle. 
   As shown in  FIG. 3 , the lever  22  fits over the shaft  38  of the base  21  and ball bearings  46  are inserted in the openings  44 . A first flat washer  48  is placed over the ball bearings  46  to retain them in the openings  44 . A spring washer  50  is compressed between the first flat washer  48  and a second flat washer  52  by the fastener  23  to spring bias the ball bearings, but not the lever, toward the base  21 . A bushing  54  passes through the first flat washer  48  and spring washer  50  to engage the top of the shaft  38  and retain the lever  22  in its position about the shaft. The shaft  38 , lever  22  washers  48 ,  50 ,  52  and bushing  54  are selected so that when the fastener  23  is tightened to secure the assembly to a PC board as shown in  FIG. 1 , pressure from the spring washer  50  is exerted against the ball bearings  46  via the first flat washer  48 , while the lever  22  is retained about the shaft but permitted free rotational movement. In the disclosed embodiment, the bushing  54  has an outside diameter greater than the diameter of the shaft  38 , providing a shoulder that holds the lever  22  in position. 
   When the ball bearings  46  are aligned with pairs of holes  34  on the base  21 , the spring bias on the ball bearings  46  seats them in the holes  34  to positively define a distinct position of the lever  22  with respect to the base  21 . Distinct switch positions are important in the emergency vehicle environment, where operators may be wearing gloves and are likely to be distracted when operating emergency warning equipment. To move the lever  22  from a position where the ball bearings  46  are seated in a pair of holes  34 , sufficient pressure must be applied to the arm  24  to overcome the spring bias of the spring washer  50 . It should be noted that the fastener  23 , flat washers  48 ,  52 , spring washer  50 , bushing  54 , and ball bearings  46  are all standard hardware items. 
   The illustrated PC board-mounted switches  14 ,  16  are also standard off the shelf items. One example of an appropriate switch is the TL  1105  single pole, single throw switch, available from E-Switch. These switches have an actuator  15  projecting from the switch body in a direction substantially parallel to the PC board  18 . The switch actuator  15  of the selected switches must be moved approximately ten thousandths of an inch (0.010″) to change the state of the switch contacts. Each lobe  28 ,  30  of the actuating surface  20  of the lever  22  projects radially approximately twenty thousandths of an inch (0.020″) to reliably actuate the switches  14 ,  16 . The electrical contacts of the selected switches  14 ,  16  are normally open, with the switch actuators biased toward the extended position shown in  FIG. 5 . Those skilled in the art will recognize that opposite electrical states for a given lever position could be generated by switches having a normally closed configuration. It will also be apparent that selecting normally closed switches and reversing the profile of the actuating surface would duplicate the electrical states generated by the disclosed components. 
     FIG. 5  illustrates the angular relationships among the components of the disclosed lever switch. The disclosed lever assembly is designed to provide four distinct lever positions distributed over an arc  56  of approximately 67.5°. The ball bearing detents  34  are arranged to define four lever positions separated by an arc  58  of approximately 22.5° when the spring-biased ball bearings  46  seat in diametrically opposed pairs of detents  34 . The switches  14 ,  16  are separated from each other by an arc  56  of about 67.5° and arranged on the PC board so that their actuators  15  move in a direction aligned with the axis of rotation A R  of the lever  22 . The actuating surface  22  of the lever includes two radially projecting lobes  28 ,  30 . Each lobe in the disclosed embodiment has an arcuate length sufficient to actuate a switch in two adjacent lever positions. 
     FIGS. 6 through 9  show the relative positions of the base  21 , lever  22  and actuators  15  of switches  14 ,  16  corresponding to each of the four lever positions.  FIGS. 6-9  illustrate the base  21 , lever  22  and switches  14 ,  16  from beneath the base as it is shown in  FIGS. 1 ,  3  and  4  (or looking down from above in the orientation shown in  FIG. 10 ). The disclosed lever switch  10  may be mounted to either the top or bottom surface of a PC board  18  and may be configured to operate from left to right (counter clockwise), as shown in  FIGS. 6-9 , or right to left (clockwise), by reversing (flipping over) the installed position of the lever  22  with respect to the base  21 . The positions of the ball bearings  46  in  FIGS. 6-9  are shown by the large concentric circle over opposed detents  34 . 
     FIG. 6  illustrates the lever  22  in a first position corresponding to an off state, where neither lobe  28 ,  30  is engaged with the actuator  15  of a switch  14 ,  16 . Given that the selected switches are normally open, the output state associated with the lever position illustrated in  FIG. 6  is 0-0, both switches being open. 
     FIG. 7  shows the lever in a second position, with the actuator  15  of switch  16  engaged by lobe  30 . This lever position corresponds to a 1-0 output state, with one switch closed and the other switch remaining open. 
     FIG. 8  shows the lever in a third position, with the actuator  15  of switch  16  still engaged with lobe  30  and the actuator  15  of switch  14  engaged by lobe  28 . This lever position corresponds to a 1-1 output state, both switches being closed. 
     FIG. 9  shows the lever in a fourth position, with the actuator  15  of switch  16  released by lobe  30  and the actuator  15  of switch  14  still engaged by lobe  28 . This lever position corresponds with a 0-1 output state, one switch being open and the other switch being closed. 
   Thus the disclosed lever switch provides outputs corresponding to four electrical states 0-0, 1-0, 1-1 and 0-1. These electrical states may be employed as inputs to an electronic circuit or micro-controller to produce corresponding outputs. 
     FIGS. 1 and 10  illustrate the disclosed lever switch  10  mounted to a PC board  18 . A flat washer  60  is placed beneath the base  21  to permit sufficient tightening of the fastener  23  without bending or damaging the PC board  18  or base  21 . The disclosed switch assembly may be mounted to the top or bottom of a PC board. It will be understood that if all components are arranged in the mirror image positions on the opposite side of a PC board, lever action will be reversed. Flipping the lever  22  over with respect to the base  21  reverses the actuating direction. 
   The present invention has been described in the context of specific embodiments. Other alternatives, modifications and variations will become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications and variations that fall within the broad scope of the appended claims.