Abstract:
Embodiments of the present invention provide switch cells that use a non-electrical tactile feedback pad to adjust the tactile feel of the included switches. As a non-limiting advantage, separating the tactile feedback pad from the electrical switching operation allows the electrical contacts to be configured for high-current applications while relying on the tactile feedback pad to define or “tune” the tactile feel of the switch cell. Moreover, the same switch cell design may be used to meet a variety of tactile feel requirements, simply by installing different tactile feedback pads. That is, the same switch cell can be reconfigured to have a different tactile response curve simply by changing out the tactile feedback pad(s) used in the switch cell, without affecting the electrical characteristics of the switch cell.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to switch cells and particularly relates to a switch cell apparatus having a non-electrical tactile feedback pad. 
       BACKGROUND 
       [0002]    Automobiles represent a prime, but not an exclusive, example of the burgeoning market for electrical switches. A typical power seat in a modern automobile has multiple switches associated with it, e.g., one or more switch cells for adjusting forward/aft position, seat angle, lumbar support settings, etc. The tactile feel of the switches integrated into these switch cells represents a critical element of the “user experience.” Consequently, vehicle manufacturers, or the Original Equipment Manufacturers (OEMs) that supply them, often specify particular tactile curves for different switches, or for different switch functions, and for different switch applications, e.g., luxury or high-end applications versus economy or basic applications. 
         [0003]    Switch cell manufacturers face significant challenges in controlling the number of switch designs needed to satisfy the varied and changing tactile feel requirements. Further complications arise in meeting the electrical requirements applicable to at least some types of switch cells. For example, so-called dome switches use a collapsible rubber dome or “pillow” as a movable switch contact, where the underside of the dome includes a carbon pad or other conductive material. 
         [0004]    However, dome switches are, in general, not suitable for use in high current applications, such as where the switch cell will be used to switch current to the motors used for power seat adjustment. High-current switches commonly use “hard” switch contacts, i.e., sets of metallic contacts. While metallic switch contacts are well suited for switching the high currents associated with power seat motors, they tend to be loud and setting or controlling their tactile feel is challenging. 
       SUMMARY 
       [0005]    Embodiments of the present invention provide switch cells that use a non-electrical tactile feedback pad to adjust the tactile feel of the included switches. As a non-limiting advantage, separating the tactile feedback pad from the electrical switching operation allows the electrical contacts to be configured for high-current applications while relying on the tactile feedback pad to define or “tune” the tactile feel of the switch cell. Moreover, the same switch cell design may be used to meet a variety of tactile feel requirements, simply by installing different tactile feedback pads. That is, the same switch cell can be reconfigured to have a different tactile response curve simply by changing out the tactile feedback pad(s) used in the switch cell, without affecting the electrical characteristics of the switch cell. 
         [0006]    According to some embodiments, a switch cell includes a housing assembly and a switch comprising first and second electrical contacts configured as a contact pair and supported within the housing assembly. The switch cell also includes a non-electrical tactile feedback pad separate from the switch and supported within the housing assembly. The tactile feedback pad has a configured compression force profile for imparting a desired tactile curve associated with actuation of the switch via an actuator assembly that is movably supported within the housing assembly. The actuator assembly comprises a first member extending to an exterior of the housing assembly and coupled to one or more interior members that are configured to actuate the switch while simultaneously compressing the tactile feedback pad when the first member is moved in a defined switch actuation direction. 
         [0007]    Of course, the present invention is not limited to the above features and advantages. Those of ordinary skill in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of one embodiment of a switch cell. 
           [0009]      FIG. 2  is an electrical schematic of the switch cell of  FIG. 1 . 
           [0010]      FIG. 3  is a cutaway perspective view of one embodiment of a switch cell. 
           [0011]      FIGS. 4 and 5  are exploded views of example embodiments of a switch cell. 
           [0012]      FIGS. 6 and 7  are diagrams of example tactile curves for a switch cell. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  is a perspective view of one embodiment of a witch cell  10  that includes a housing assembly  12  that includes a cover  14  and a housing  16 . The switch cell  10  further includes one or more leads or terminals  18 , for electrical connections. 
         [0014]      FIG. 2  is an example, non-limiting electrical schematic of the switch cell  10 . According  FIG. 2 , the switch cell  10  provides switches four connections, such as for up/down and fore/aft motors in a powerseat. 
         [0015]      FIG. 3  depicts a cutaway view of the switch cell  10 . One sees that the switch cell  10  includes at least one switch  20  comprising first and second electrical contacts  22  and  24 . The electrical contacts  22  and  24  are configured as a contact pair and are supported within the housing assembly  12 . In particular, in the illustration, two such switches  20 - 1  and  20 - 2  are visible, and each has first and second contacts  22  and  24 . It will be understood that, with respect to the example schematic of  FIG. 2 , the switch cell  10  would also have switches  20 - 3  and  20 - 4  (not illustrated). Unless needed for clarity, the reference number “ 20 ” without any suffix is used to refer to any given switch or switches. 
         [0016]      FIG. 3  further illustrates that each switch  20  has a corresponding non-electrical tactile feedback pad  26  that is separate from the switch  20  and is supported within the housing assembly  12 . in the illustration, the switch  20 - 1  is associated with a tactile feedback pad  26 - 1  and the switch  20 - 2  is associated with a tactile feedback pad  26 - 2 . For a given switch  20 , the corresponding tactile feedback pad  26  has a configured compression force profile, for imparting a desired tactile curve associated with actuation of the switch  20 . 
         [0017]    In the illustrated switch cell configuration, actuation of the switches  20  within the housing assembly  12  is accomplished via an actuator assembly  28  that is movably supported within the housing assembly  12 . For example, the actuator assembly  28  may be configured as a joystick-like actuator that provides multi-axis actuation. 
         [0018]    Here, the actuator assembly  28  comprises a first member  30  that extends to an exterior of the housing assembly  12  and is coupled to one or more interior members  32 . The interior member(s)  32  are configured to actuate one or more of the switches  20  supported within the housing assembly  12  while simultaneously compressing the corresponding tactile feedback pad(s)  26  when the first member  30  is moved in a defined switch actuation direction. For example, if the first member  30  is moved or tilted towards the switch  20 - 1 , the end  34 - 1  of a member  32 - 1  moves downward to actuate the switch  20 - 1  and, at the same time, the end  34 - 2  of the member  32 - 2  moves upward into compressive engagement with the tactile feedback pad  26 - 1 . In other words, actuating the switch  20 - 1  compresses the tactile feedback pad  26 - 1 . The same is true with respect to actuation of the switch  20 - 2  and the corresponding tactile feedback pad  26 - 2 . 
         [0019]    Consequently, while each switch  20  within the housing assembly  12  may contribute to a portion of the overall tactile feel experienced by a user when actuating the switch  20  via the actuator assembly  28 , the overall tactile feel is established by the compression force profile of the tactile feedback pad  26  corresponding) the switch  20 . That is, the tactile feedback pad  26  can be used to establish or tune the tactile feel, and a switch cell  10  that is otherwise the same as another switch cell  10  of the same design can exhibit markedly different tactile response curves simply by installing different tactile feedback pad(s)  26  in it. 
         [0020]    Thus, in at least one embodiment, a switch cell  10  as contemplated herein includes first and second switches  20 - 1  and  20 - 2 . Correspondingly, the one or more interior members of the switch actuation assembly  28  comprise opposing first and second actuator arms  32 - 1  and  32 - 2  that are configured to move in unison in opposing directions. According to the depicted configuration, moving the first member  30  in a first switch actuation direction causes the first actuator arm  32 - 1  to actuate the first switch  20 - 1  while simultaneously causing the second actuator arm  32 - 2  to compress a first non-electrical tactile feedback pad  26 - 1 . Conversely, moving the first member  30  in an opposite, second switch actuation direction causes the second actuator arm  32 - 2  to actuate the second switch  20 - 2  while simultaneously causing the first actuator arm  32 - 1  to compress a second non-electrical tactile feedback pad  26 - 2 . 
         [0021]    Notably, the first and second electrical contacts  22 ,  24  of each switch  20  may be a pair of metallic contacts adapted for switching currents in excess of one Ampere. This feature makes the switch cell  10  well suited for high-current applications, which stands as an additional advantage on top of the advantageous ability to tailor the tactile feel of the switch cell  10  via tactile feedback pad(s)  26 , which may be made removable or at least interchangeable between switch cells  10  of the same design. 
         [0022]    In at least some embodiments, the one or more interior members  32  are configured in a rocker arm arrangement. The interior members  32  of the rocker arm arrangement include at least the first actuator arm  32 - 1  extending within the interior of the housing assembly  12  and an opposing second actuator arm  32 - 2  extending within the interior of the housing assembly  12 . The first actuator arm  32 - 1  has a first end  34 - 1  positioned between a first switch  20 - 1  and a second non-electrical tactile feedback pad  26 - 2 . The second actuator arm  32 - 2  has a second end  34 - 2  positioned between a second switch  20 - 2  and a first non-electrical tactile feedback pad  26 - 1 . 
         [0023]    Here, “between” can be understood as the rocker arm end  34 - 1  (or  34 - 2 ) having a tactile feedback pad  26 - 1  (or  26 - 2 ) above it and having an electrical contact  22  or  24  for the switch  20 - 1  (or  20 - 2 ) below it. Of course, the terms “above” and “below” are not intended to be limiting and are used merely to establish a convenient frame of reference with respect to the switch orientation seen in  FIGS. 1 and 3 , for example. With this arrangement, tilting the first member  30  in a first direction causes the first end  34 - 1  to actuate the first switch  20 - 1  and causes the second end  34 - 2  to engage the first tactile feedback pad  26 - 1 . Tilting the first member  30  in an opposite second direction causes the second end  34 - 2  to actuate the second switch  20 - 2  and causes the first end  34 - 1  to engage the second tactile feedback pad  26 - 2 . 
         [0024]      FIG. 4  illustrates an exploded view of a first design of a 4-way switch cell  10 . The actuator assembly  28  includes an anti-rattle plunger  40  on a spring  42  that inserts into or otherwise engages with the first member  30 . 
         [0025]    One also sees that a member  44  formed here as a disk includes or carries a number of tactile feedback pads  26 , e.g., one tactile feedback pad  26  for each switch  20  included in the switch cell  10 . The four switches  20  implemented in this embodiment are formed using a common normally-closed terminal  46 , a set of four movable springs  48 , a set of four movable arms  50  with contact pills, a set of four hooks  52 , and a set of four contact terminals  54 . 
         [0026]      FIG. 5  illustrates a similar arrangement, except that the switches  20  are formed using a set of four normally-closed terminals  56 , a set of four movable arms  58  with electrical contact pills, a set of common terminals  60 , and a set of normally-open terminals  62 . 
         [0027]      FIGS. 4 and 5  can, therefore, be understood as depicting example details for implementing non-electrical tactile feedback pads  26  within the switch cell  10 . In particular, a tactile feedback pad  26  may be implemented as part of a member  44  that is removably supported within the housing assembly  12  of the switch cell  10 . 
         [0028]    The member  44  comprises, for example, a disk made of elastomeric or other resilient material. In one such embodiment, each tactile feedback pad  26  comprises a collapsible dome formed within the resilient member  44 . In another embodiment, each tactile feedback pad  26  comprises a thickened section of the member  44 . The tactile feedback pad  26  thus operates as a soft stop for limiting the travel of the actuator assembly  28 . 
         [0029]    Implementing the tactile feedback pads  26  via the member  44  allows a switch cell manufacturer to build or reconfigure a given switch cell  10  with a particular tactile feedback response, or with a particular set of tactile feedback responses for multiple included switches  20 , simply by selecting or changing the member  44 . The same switch cell  10  can be imbued with different tactile feedback responses merely by selecting the appropriate member  44 . Moreover, it should be understood that in cases where the member  44  carries more than one tactile feedback pad  26 , two or more of those tactile feedback pads  26  may have different compression force profiles i.e., they may provide different tactile feel response curves. 
         [0030]    Still further, any one or more of the tactile feedback pads  26  carried by the member  44  may have a “snap” actuation or a non-snap actuation, where a snap actuation has a markedly non-linear compression force profile that results in higher initial resistance, followed by sharp or step-change lowering of resistance as the tactile feedback pad  26  is compressed beyond a certain point or amount. In this regard, the tactile feedback pads  26  can be formed as domes or pillows in the member  44 , or merely as thickened areas of the member  44 , or the entire member  44  may be formed such that it has a broad, possibly continuous area or region where any point is suitable for use as a tactile feedback pad  26 . 
         [0031]    Regardless of the particulars by which the tactile feedback pad(s)  26  are implemented in the member  44 , in one or more embodiments the member  44  is configured to isolate a lower interior portion of the housing assembly  12 , when it is installed within the housing assembly  12 . The member  44  thereby provides at least one of sound isolation and water resistance for the switch(es)  20  positioned within the lower interior portion of the housing assembly  12 . Thus, as a further advantage in some embodiments, the member  44  not only serves as a carrier for the tactile feedback pad(s)  26 , it reduces switching sounds and provides fluid and/or contamination resistance for the switches)  20 . Correspondingly, in at least some embodiments, the switch cell  10  is configured such that the tactile feedback pad  26  is installable in and removable from the housing assembly  12  independent of the switch(es)  20 . 
         [0032]    The overall tactile curve exhibited by a switch  20  in the switch cell  10  can be understood as the sum of two tactile curves: the tactile curve of each of the switch  20 , and the tactile curve of the corresponding tactile feedback pad  20 . The curve associated with tactile feedback pad  26  may, however, be dominant. 
         [0033]      FIGS. 6 and 7  are two examples of switch cell tactile curves built using a “non-snap” type and a “snap” type ePad, respectively.  FIG. 6  shows three non-snap tactile curves on a graph. The lower tactile curve corresponds to the switch  20  and can be understood as representing its “native” or inherent tactile response curve. The middle tactile curve represents the tactile response curve of the tactile feedback pad  26  used in conjunction with the switch  20 . The upper tactile curve shows the resulting sum of tactile response curves for the switch  20  and the tactile feedback pad  26  and thus represents the tactile response experienced by a user when actuating the switch  20 . 
         [0034]    Note that in this example, the 0.75 mm mark represents the point of contact closure for the switch  20 , and the 1.50 mm mark represents the hard stop limit of the switch  20 . One sees that the tactile response curve of the tactile feedback pad  26  dramatically softens or otherwise masks the hard stop exhibited by the bare switch  20 . In other words, one of the several advantages gained by use of the tactile feedback pad  26  is that it imparts a “soft stop” characteristic to the overall switch cell  10 , as the user encounters the travel limit of the switch  20 . 
         [0035]      FIG. 7  illustrates a similar scenario, except that the tactile feedback pad  26  at issue is configured with a snap-type response. Thus, the switch cell  10  can be configured with snap-type tactile feedback pads  26 , or with non-snap-type tactile feedback pads  26 , or with a mix of snap-type and non-snap-type tactile feedback pads  26 . 
         [0036]    Further, the actuator knobs or appendages that are typically fastened to the first member  30  of the switch actuator assembly  28  in a finished installation may be asymmetrical and may include shapes other than squares, cylinders or spheres, Accordingly, the tactile feedback pad  26  may be designed with different tactile curves corresponding to different actuator movement directions, in order to balance the feel experienced by the user for the different actuation directions, or to impart distinctively different tactile feel to different actuation directions and/or different adjustment functions. 
         [0037]    Notably, modifications and other embodiments of the disclosed inventions) will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. For example, a sliding rather than a rocking actuator may be used in the switch cell  10 , with the sliding actuator sliding into engagement with one or more tactile feedback pads  26  when a switch  20  is actuated. 
         [0038]    Therefore, it is to be understood that the invention(s) is/are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.