Abstract:
A low profile switch assembly is provided having a base portion that supports a folded flexible circuit sealed about its edges, an overlying deformable elastomeric portion, and a pair of window knobs. The base portion has a pair of integrally formed, upwardly extending posts that pivotally support the window knobs and encourage alignment of the flexible circuit and the overlying elastomeric pad. A series of domes are formed in the elastomeric pad, pairs of which are operated sequentially by the window knob acting on a lever bridging the pairs of domes. The domes, when collapsed, compress portions of the flexible circuit to bridge opposing traces within the folded circuit to actuate respective switches. The arrangement of the components provides a low profile device that inhibits contamination and uses fewer parts.

Description:
[0001]     This application claims priority from U.S. Provisional Patent Application No. 60/741,872 filed Dec. 5, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to electrical switches, and more particularly to multi-stage electrical switches.  
       DESCRIPTION OF THE PRIOR ART  
       [0003]     Electrical switches are used for controlling electrical circuits. Many electrical switches are constructed from a combination of mechanical and electrical components. Such switches translate user input to an electrical control signal. For example, a light switch having an external toggle enables a user to selectively open and close a circuit for turning “on” and “off” a light.  
         [0004]     In automotive applications, electrical switches are often used for controlling electro-mechanical systems such as power windows that open and close automobile door windows. These window switches may often be integrated into a console or door frame along with other electrical switches, e.g. power door locks. As the number of electrically controlled components in an automobile increases, the space available for housing these components can become limited.  
         [0005]     Electrical components used in an automobile are also prone to contamination due to the nature of activities that may occur during operation of the automobile. For example, a beverage that is spilled while driving may contaminate electrical switches and their accompanying circuitry. Therefore, the arrangement of the components in the switches need be considered, as well as their placement within the vehicle.  
         [0006]     In addition to their inherent increased space requirement in the console of the vehicle, larger and more extensive switches require additional material, such as plastic, for certain components, as well as larger or more complicated circuit boards, which can increase cost. For example, circuit boards containing fibreglass, e.g. printed circuit boards (PCB), can increase the cost of a component, due to a relative increase in the cost of the fibreglass used to construct the PCB.  
         [0007]     Accordingly, cost, reliability and size are important considerations when implementing electrical switches for operating electro-mechanical systems in an automobile.  
         [0008]     Various prior art window switches teach specific arrangements for implementing switches in an automobile. In particular, such prior art switches teach multi-functional switches using a single toggle or “window knob”. A single window switch may be used to provide dual-stage operation in both forward and rearward directions. The common application for such switches is to provide manual and automatic window operation for opening and closing same, wherein the application of a first force operates the window switch in a manual mode, and the application of a second force, being greater than the first force, operates the window switch in an automatic mode. Typically by applying the second force, the window continues to open without further tilting of the window knob. Generally, these window switches offer tactile feedback to the user enabling the user to discern between the manual mode and the automatic mode.  
         [0009]     Examples of the above type of prior art switches are shown in U.S. Pat. Nos. 6,737,592 to Hoang et al., published on May 18, 2004; 6,914,202 to Sugimoto et al., published on Jul. 5, 2005; and 5,719,361 to Lee, published on Feb. 17, 1998.  
         [0010]     The arrangements taught in these prior art examples utilize a relatively high profile, therefore requiring a greater amount of space in the console of the vehicle, and a greater amount of material to construct the components. In particular, Lee uses a large shroud for supporting the window knob, with a separate base to support the various other components. Sugimoto has a relatively high profile pusher that is supported by an equally high profile housing. Hoang also has a high profile support for accommodating slidable paddles for operating on the underlying switch circuitry. Clearly, these arrangements do not provide a simple or compact device, and would generally require a greater amount of space in an automobile console, as well as an increased amount of material.  
         [0011]     Moreover, none of the above prior art examples offer an arrangement that is suitable for inhibiting contamination. Sugimoto in particular uses many moving parts that could become stuck together if a tacky contaminate such as a soft drink seeped into the switch. Moreover, the arrangement taught by Lee would enable contaminates to seep between layers once the contaminates enter beneath the shroud. In fact, a tacky substance may cause the layers to stick together whilst covering critical contact areas or create an unwanted separation between the layers. Furthermore, it would be a somewhat complicated task to disassemble the switch in order to remove or clean away contaminates, and due to such a burden of labour, the switch may possibly be replaced in its entirety, which does not exhibit reliability of the component.  
         [0012]     There exists a need for an electrical switch that can address at least one of the above-described problems, namely one that reduces one or more of cost, size, and the potential for contamination.  
         [0013]     It is therefore an object of the present invention to provide an electrical switch that obviates or mitigates at least one of the above-mentioned disadvantages.  
       SUMMARY OF THE INVENTION  
       [0014]     In one aspect, a switch assembly comprising a base portion having at least one integrally formed post extending upwardly therefrom. The post pivotally supports an actuator member, and the base portion supports a flexible circuit portion interposed between the base portion and an elastomeric portion. The elastomeric portion has at least one collapsible dome formed therein, wherein the actuator member interacts with the at least one dome upon pivotal movement thereof to collapse the dome and compress the circuit portion to actuate a switch thereof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     An embodiment of the invention will now be described by way of example only with reference to the appended drawings wherein:  
         [0016]      FIG. 1  is a partial perspective view of the interior of an automobile;  
         [0017]      FIG. 2  is a perspective view of an embodiment of a window switch shown in  FIG. 1 , in situ;  
         [0018]      FIG. 3  is an exploded view of the components of the window switch shown in  FIG. 2 ;  
         [0019]      FIG. 4 ( a ) is a sectional view of a portion of the window switch shown in  FIG. 2  along the line IV-IV;  
         [0020]     FIGS.  4 ( b ) and  4 ( c ) show sequential operational views of the portion shown in  FIG. 4 ( a );  
         [0021]      FIG. 5  is a sectional view of a window knob shown in  FIG. 3  along the line V-V;  
         [0022]      FIG. 6  is a sectional view of the switch shown in  FIG. 3  along the line VI-VI; and  
         [0023]      FIG. 7  is a sectional view of the folded flexible circuit shown in  FIG. 3  along the line VII-VII. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     Referring therefore to  FIG. 1 , a switch assembly is generally denoted by numeral  10 . In the exemplary environment shown in  FIG. 1 , the switch assembly  10  is used for powering door windows (doors and windows not shown) in an automobile  14 , and is installed in a central console  12 , between a pair of seats  18  (only one shown). The switch assembly  10  is supported in the console  12  with a panel  16 .  
         [0025]     The switch assembly  10  is shown in  FIGS. 2 and 3  in assembled and exploded views respectively. In the figures, equivalent components are given equivalent reference numerals. The switch assembly  10  includes a base portion  20  that supports a folded flexible circuit  22 , an overlying deformable elastomeric portion  24 , and a pair of actuation buttons, in this example, window knobs  26 .  
         [0026]     The base portion  20  has a pair of upwardly extending posts  30 , each of which is generally “C-shaped” and has a pair of inwardly protruding flanges  38 . The posts  30  are integrally formed with and extend from a generally planar stage  31 . A downwardly projecting female connector  32  is formed on the underside of the base portion  20 . The connector  32  has a series of pins  34  that extend through the stage  31  at their one end, and mate with a corresponding male connector  33  at their other end. The connectors  32  and  33  may be any suitable electrical connector, and are preferably standard automotive electrical connectors. The base portion  20  also has a series of mounting holes  35  and an alignment post  36  for aligning the elastomeric portion  24  thereon. It will be appreciated that the base portion  20  may also incorporate other features, such as channels for accommodating a light pipe (not shown) and shall not be restricted to the arrangement shown in  FIGS. 2 and 3 .  
         [0027]     The flexible circuit  22  shown in  FIGS. 3 and 7 , is a unitary flex-circuit board that is folded over itself along edge  41  to define an upper circuit layer  40  and a lower circuit layer  42 . The layers  40  and  42  are preferably sealed about their edges to create a sealed edge  48 . Sealing the edges of the layers  40  and  42  protects the circuitry within the folded flex-circuit, the features of which will be explained later. The flexible circuit  22  has a pair of channels  44  and  46  formed therein to accommodate passage of the posts  30  therethrough whilst the flexible circuit  22  is supported on the stage  31 . In the example shown in  FIG. 3 , the circuit  22  has a pair of holes  43  that align with two of the holes  35  on the stage  31 . When positioned, the end of the circuit  22  opposite the folded edge  41  terminates prior to the other two of the holes  35  and the alignment post  36 . The planar stage  31  provides a stable support for the flexible circuit  22 .  
         [0028]     The flexible circuit  22  includes an inner layer  70  which is sandwiched between the upper layer  40  and lower layer  42 , within the edge  48 , of the flexible circuit  22 . The inner layer  70  has a first aperture  83  and a second aperture  87  that enable the upper layer  40  to interact with the lower layer  42  through compression of the flexible circuit  22  in the region of the apertures  83  and  87 . Further detail of the flexible circuit  22  is shown in  FIG. 7 .  
         [0029]     The upper layer  40  has a first upper contact  72  secured to its inwardly directed surface  112  positioned in alignment with the first aperture  83 , and a second upper contact  74  secured to its inwardly directed surface  112  positioned in alignment with the second aperture  87 . The lower layer  42  has a first set of spaced apart contacts  76  secured to its inwardly directed surface  114  positioned in alignment with the first aperture  83 , and a second set of spaced apart contacts  78  secured to its inwardly directed surface  114  positioned in alignment with the second aperture  87 . As shown in  FIG. 4 ( a ), the inner layer  70  maintains a spaced apart relationship between the contact  72  and the contacts  76 , and the contact  74  and the contacts  78 .  
         [0030]     The elastomeric portion  24  is a unitarily formed piece that includes a skirt  25  extending from a generally planar pad  51  to cover the edges of the stage  31  of the base portion  20 , as shown in  FIG. 2 . The pad  51  includes a series of downwardly extending nubs  59  that are sized to snugly fit into the holes  35 , and a collar  57  that is sized to snugly fit around the alignment post  36 . A pair of windows  50  are formed in the pad  51 , and are sized to allow passage of the posts  30  therethrough. The elastomeric portion  24  includes actuators  52  that cooperate with the circuit  22  to control movement of the window. In the example shown in  FIG. 3 , the pad  51  has four sets of actuators  52 . In this example, a pair of actuators  52  are aligned to interact with a respective one of the window knobs  26 . As is best seen in  FIG. 4 , each actuator  52  includes a first collapsible dome  56  having a nub  53 , a second collapsible dome  54  having a nub  55 , and a lever  58  that bridges the domes  54  and  56 . The domes  54  and  56  are unitarily formed in the pad  51 , and the lever  58  comprises a separate component that is preferably formed from a rigid piece of metal. The lever  58  has a pair of holes  61  that are sized to snugly fit on the nubs  53  and  55 .  
         [0031]     The first dome  56  includes an integrally formed neck  82 , collapsible annular ring  80 , and an interior downwardly extending protrusion  84  that is positioned in alignment with the first aperture  83  of the flexible circuit  22 . Similarly, the second dome  54  includes an integrally formed neck  88 , collapsible annular ring  86 , and an interior downwardly extending protrusion  90 . The domes  56  and  54  are differently shaped. In this embodiment, the neck  82  is longer than the neck  88 , and the ring  80  is shorter than the ring  86 . The protrusions  84  and  90  are similar in dimension. Consequently, the distal end of the protrusion  84  is closer to the outer surface  110  of the upper layer  40  than the protrusion  90 .  
         [0032]     The actuators  52  are controlled by the window knob  26  shown in  FIGS. 5 and 6 . The window knob  26  is preferably a plastic component having an ergonomically formed shell  64  that enables a user to tilt the knob  26  in the fore and aft directions. A forward protrusion  60  and a rearward protrusion  62  extend from beneath the shell  64 . The knobs  26  are pivotally supported by respective posts  30  as explained below.  
         [0033]     The protrusion  60  interacts with the lever  58  at a point that is closer to the first dome  56  than the second dome  54  to create an offset fulcrum. Consequently, a force transferred from the protrusion  60  to the lever  58  will cause the first dome  56  to collapse before the second dome  54 , in a sequential manner as will be described in more detail later.  
         [0034]     The window knob  26  is shown in greater detail in the sectional view of  FIGS. 5 and 6 . As best shown in  FIG. 5 , the shell  64  has a pair of sidewalls  100  and  102 , and a pair of inner support walls  104  and  106 . Each support wall  104 ,  106  has an attachment hole  108 . The holes  108  are sized to receive the inwardly facing flanges  38  of the posts  30  to enable pivotal attachment of the window knob  26  to the base  20 . Consequently, the window knob  26  will pivot about an axis defined by respective pairs of the flanges  38  when tilted by a user, in either the fore or aft directions. Although the sectional view of  FIG. 4 ( a ) illustrates only the interaction of the forward protrusion  60  with the lever  58 , it will be appreciated that the rearward protrusion  62  interacts with another of the levers  58  in a similar manner, through a rearward tilting movement of the window knob  26 .  
         [0035]     The components shown in  FIG. 3  are assembled as shown in  FIG. 2  by first aligning the channels  44  and  46  of the circuit  22  with the posts  30  of the base, and sliding the flexible circuit  22  over the posts  30  until it is aligned and stably supported by the stage  31 . The holes  43  should align with two of the holes  35  and typically, the pins  34  will extend through or interact with the circuit  22  such that they can be soldered or otherwise connected thereto for permanent assembly of the switch  10 . Accordingly, the flexible circuit  22  may transmit and receive electrical signals through the connector  32  once assembled with the base  20 . Once assembled, the circuit  22  should lie flat on the stage  31  and be stably supported thereby.  
         [0036]     The windows  50  of the elastomeric portion  24  may then slide over the posts  30 , and the pad  51  will cover the circuit  22  while the skirt  25  extends over the stage  31 . The pad  51  is aligned and secured to the base  20  through fitment of the nubs  59  within the holes  35 , and the collar  57  over the alignment post  36 . Once the elastomeric portion  24  is securely positioned, the pad  51  should lie substantially flat on the circuit  22 . Such arrangement aligns the domes  54  and  56  with the apertures  83  and  87  respectively.  
         [0037]     The levers  58  may then be supported on the domes  56  and  54  through fitment of the nubs  53  and  55  with respective ones of the holes  61 . It will be appreciated that the levers  58  may be assembled with the elastomeric portion  24  in advance of assembling the switch assembly  10 , and that the above assembly procedure is provided for illustrative purposes only. The window knobs  26  may then be attached to the posts  30  for pivotal movement thereon.  
         [0038]     The assembly  10  shown in  FIG. 2  results in a series of layers that interact to operate the actuators  52 . Such layering is shown in the sectional view of  FIG. 4 ( a ). As can be seen in the figure, when assembled, the stage  31  provides a flat, stable support for the flexible circuit  22 .  
         [0039]     As most apparent in  FIG. 2 , the integrally formed posts  30  and stage  31  provide pivotal support for the window knobs  26  and stable support for the flexible circuit  22  and the elastomeric portion  24  whilst maintaining a low profile. The posts  30  encourage alignment of the layers, and the stage  31  enables the pad  51  to be secured thereto. The skirt  25  and the sealed edge  48  both inhibit contamination of the flexible circuit  22 . The contacts  72 - 78  are thus protected from their environment prolonging their lifetime, and maintaining reliable operation therethrough.  
         [0040]     The operation of the switch assembly is as follows, making reference to FIGS.  4 ( a )-( c ). In the switch assembly&#39;s rest position, the protrusions  84  and  90  lie above the upper surface  110  of the upper layer  40  of the flexible circuit  22 , and the forward protrusion  60  rests on the lever  58 . As shown in  FIG. 4 ( b ), forward tilting of the window knob  26  using a first force F 1  transfers this force through the protrusion  60  to the lever  58 , that, due to the offset fulcrum, first operates on the first dome  56  to collapse the ring  80  and thereby cause the protrusion  84  to engage the upper surface  110  of the upper layer  40 . Although the flexible circuit  22 , and pad  51  are stably supported by the stage  31 , the aperture  83  enables compression of the upper layer  40  in the region of the aperture  83  whereby F 1  causes the contact  72  to bridge the spaced apart contacts  76  and close a first circuit path (not shown) of the flexible circuit  22 . In this example, the application of F 1  provides a first switching stage for manual operation of an automobile window.  
         [0041]      FIG. 4 ( c ) shows a second switching stage wherein the application of a second force F 2  being greater than F 1  causes further downward translation of the lever  58  such that the lever  58  next operates sequentially on the second dome  54  to collapse the ring  86  and thereby cause the protrusion  90  to engage the upper surface  110  of the upper layer  40  in the region of the second aperture  87 . The application of F 2  causes the contact  74  to bridge the spaced apart contacts  78  to close a second circuit path (not shown) of the flexible circuit  22 . In this example, the application of F 2  provides a second switching stage for automatic operation of the automobile window, which thereafter requires no further operation of the window knob  26  to completely open the window.  
         [0042]     Tilting the window knob  26  in the rearward direction will operate a second actuator  52  in a similar manner. It will be appreciated that the assembly  10  shall not be limited to the arrangement shown in  FIGS. 2 and 3 , and that any number of switches and domes can be implemented depending on the particular application.  
         [0043]     It can be seen that the switch assembly  10  provides a low profile device using a minimum number of components. The upwardly extending posts  30  serve to provide support for the window knobs  26  as well as encouraging alignment of the layers provided by the elastomeric portion  24  and the flexible circuit  22 . The height of the posts  30  can be constructed to accommodate various dome structures and circuit thicknesses, as well as varying designs of window knobs  26 . The overlying skirt  25  of the elastomeric portion  24  and the sealed edge  48  of the flexible circuit  22  encourage the inhibition of contamination, whilst being stably supported by the generally planar stage  31  of the base portion  20  during operation. The elastomeric portion  24  further provides a tactile feedback to the user and offers sequential switching capabilities for applications such as automobile door windows.  
         [0044]     Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.