Patent Publication Number: US-7592562-B1

Title: Knob assembly

Description:
FIELD OF THE INVENTION 
   The present invention is directed to the field of electric switches, and more particularly to switch assemblies for electrical devices. 
   BACKGROUND OF THE INVENTION 
   Many communications devices, such as radios, typically include a rotary switch which is movable to a number of positions. In a rotary switch for a handheld satellite transceiver and other portable communications devices, these positions typically include “off,” “channels  1 - 5 ” (or more), “scan,” “front panel,” and, “Z-all” or “reset.” Generally, the reset position resets the transceiver by clearing all encryption cipher keys inputted by a user. The front panel position is typically used for allowing the channels and modes of operation to be selected using the key pad on the front panel of the transceiver. 
   Although the operation of many rotary switch designs is straightforward, many permit the transceiver to be inadvertently turned off by a user turning the rotary switch too far. In such an event, the user must then turn the transceiver back on to resume communication. In some devices, such as satellite transceivers, a reboot period of significant length is required, delaying resumption of communications. Typical switch designs may also permit inadvertent movement of the rotary switch to the reset position. Although some designs of satellite transceivers prevent resetting in the reset position by requiring actuation of a second button, the user may still inadvertently reset the satellite transceiver. 
   Some satellite transceiver designs have been proposed using “push-to-turn” rotary switches, in which pressure must be applied to the stem of the rotary switch prior switching positions. However, the stem may still be inadvertently pushed and the satellite transceiver may be reset or turned off. Other switch assembly designs have been proposed using “pull-to-turn” rotary switches in which the user must pull on the stem while changing positions. However, such switches typically require additional complexity within the rotary switch, as the pull-to-turn or push-to-turn functionality is typically included within the body of the rotary switch. This also results in switch bodies that are typically larger than those typically used in satellite transceivers, increasing the overall size of the satellite transceiver. In systems where the pull-to-turn or push-to-turn functionality is included in the knob, a groove system is typically used. However, such groove systems can be susceptible to dirt, sand, or grit, resulting in seizing or poor operation of the rotary switch. Therefore, there is a need for an improved device for controlling the operation of rotary switches in communications devices. 
   SUMMARY OF THE INVENTION 
   Embodiments of the present invention provide improved knob assemblies for reducing or eliminating switching of a rotary knob to one or more non-preferred states during a mode of operation by requiring a user to exert a force on the knob prior to allowing rotation. In a first embodiment, a switch assembly is provided. The switch assembly includes a rotary electrical switch body comprising a plurality of switch positions, a switch stem extending along a first axis and having a first end and a second end, the first end engaging the rotary switch for alternating the rotary switch body between the plurality of switch positions responsive to rotation of the switch stem about the first axis, and a knob assembly. 
   In a second embodiment of the present invention, a communications device, is provided and includes a chassis having at least one opening, a rotary electrical switch body disposed within the chassis, the rotary switch body comprising a plurality of switch positions, a switch stem extending through the opening along a first axis, the switch stem having a first end and a second end, the first end disposed within the chassis and engaging the rotary switch for alternating the rotary switch body between the plurality of switch positions responsive to rotation of the switch stem about the first axis, the second end disposed outside the chassis, and a knob assembly. 
   In the various embodiments of the present invention, the knob assembly includes a knob core contacting the second end of the switch stem, a knob collar contacting the knob core and adapted for rotating the knob core and the switch stem about the first axis, the knob collar comprising at least a first upper stop member, and a stop cam having a fixed position relative to the switch stem and disposed between the knob core and the rotary switch, the stop cam comprising at least one lower stop member having at least one feature for engaging the first upper stop member when the first upper stop member and the lower stop member are disposed along a common path. 
   In operation, the first upper stop member travels in a circumferential path normal to the first axis responsive to the knob collar rotating the knob core and the switch stem, where the knob collar is displaceable along the first axis between first and second axial positions, where the lower stop member is in the circumferential path when the knob collar is in the first axial position, and where the lower stop member is removed from the circumferential path when the knob collar is in the second axial position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a portion of satellite transceiver housing having mounted thereon a switch assembly including a rotary switch and knob assembly according to an embodiment of the present invention; 
       FIG. 2  is an exploded view of the satellite transceiver housing and the knob assembly shown in  FIG. 1 . 
       FIG. 3  is an alternate exploded view of a portion of the knob assembly shown in  FIG. 1 . 
       FIG. 4A  is a top view of the knob collar of the knob assembly shown in  FIG. 1 . 
       FIG. 4B  is a cross section view of the knob collar of the knob assembly shown in  FIG. 1 . 
       FIG. 5A  is a top view of the knob core of the knob assembly shown in  FIG. 1 . 
       FIG. 5B  is a cross section view of the knob core of the knob assembly shown in  FIG. 1 . 
       FIG. 6A  is a partial cross-section view of a portion of the knob assembly shown in  FIG. 1  when force is not exerted on the knob assembly. 
       FIG. 6B  is a partial cross-section view of a portion of the knob assembly shown in  FIG. 1  when force is exerted on the knob assembly. 
       FIG. 7  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for an “off” position of the rotary switch in  FIG. 1 . 
       FIG. 8  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for an off position of the rotary switch in  FIG. 1  after axial displacement of the knob collar according to an embodiment of the present invention. 
       FIG. 9  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  in between an off position and a first channel position of the rotary switch in  FIG. 1  during rotation of the knob collar according to an embodiment of the present invention. 
       FIG. 10  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for the first channel position of the rotary switch in  FIG. 1 . 
       FIG. 11  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for a last channel position of the rotary switch in  FIG. 1 . 
       FIG. 12  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for the last channel position of the rotary switch in  FIG. 1  after axial displacement of the knob collar according to an embodiment of the present invention. 
       FIG. 13  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  in between an the last channel position and a reset position of the rotary switch in  FIG. 1  during rotation of the knob collar according to an embodiment of the present invention. 
       FIG. 14  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for the reset position of the rotary switch in  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   Embodiments of the present invention of the provide improved knob assemblies for reducing or eliminating switching of a rotary knob to one or more non-preferred states during a mode of operation by requiring a user to exert a force on the knob prior to allowing rotation. In particular, the various embodiments of the present invention provide an improved knob assembly, in which the pull-to-turn functionality is incorporated in the knob assembly, for use with a rotary switch. The various embodiments of the present invention also utilize a stop member-based design, as opposed to existing groove-based designs, which are less susceptible to seizing or otherwise malfunction due to dirt, grit or sand. 
   Therefore, the various embodiments of the present invention provide an upper stop member and stop-based knob assembly that can be used with existing rotary switches. Consequently, the amount of interior space required inside a radio as compared to conventional push- or pull-to-turn switches is reduced, since the functionality is incorporated outside of the radio chassis. This allows existing designs to be manufactured without having to redesign the radio interior. Furthermore, some embodiments of the present invention can be used for retrofitting existing radios in the field with the improved knob assembly without the need to extract the switch from the radio. Although the present invention is described with respect to a rotary switch for a radio, the present invention is not limited in this regard. Embodiments of the present invention can be utilized in any device utilizing rotary switches and where it is undesirable to switch to at least one position inadvertently. 
   Referring initially to  FIGS. 1 ,  2 ,  3 ,  4 A,  4 B,  5 A, and  5 B, a switch assembly  1  for a radio  16  according to an embodiment of the present invention is shown. As used herein, a radio  16  can be a receiver, a transmitter, or a transceiver. However, for ease of illustration, the electronic components, other than the switch assembly  1 , are not shown. As shown in  FIGS. 1 and 2 , the radio  16  includes a chassis  17  and a switch assembly  1 , where the switch assembly  1  includes a knob assembly  10  and a rotary switch  14 . The rotary switch includes a switch body  13  having a plurality of switch positions and a switch stem  12  having a first end engaging with the switch body  13 , where the rotation of the switch stem  12  causes the switch body to alternate between different ones of the switch positions. In the case of radio  16 , alternating switch positions can place the radio  16  in different modes of operation, a previously described. 
   A “chassis” as used herein can refer to an enclosure, a frame, a mounting plate, or any other structure or feature for mounting the knob assembly  10  and the rotary switch  14 . Only a portion of the chassis  17  of the radio  16  is shown in the  FIGS. 1 and 2  for ease of illustration. In the various embodiments of the present invention, the switch body  13  and the knob assembly  10  are mounted on opposing sides of an opening in the chassis  17 . Thus, the pull-to-turn functionality is located on the exterior of the radio  16 . Such a configuration allows not only repair of the pull-to-turn mechanism without needing access to the interior of chassis  17 , but also allows retrofitting of existing rotary switches without needing to remove or replace the existing rotary switch. That is, only replacement of the existing knob assembly is required during repair or retrofit of existing switch assemblies. 
   In the various embodiments of the present invention, the knob assembly  10  includes a slider component or knob collar  22 , a stop cam  20 , and a bushing or knob core  18 . The knob assembly can also include at least one fastener  21 , a mode indicator  23 , a compression spring  24 , a spring washer, and a retention clip  26 , a cap  28 . Mode indicator  23  can be formed with a projection  30  which can act as a position indicator in conjunction with markings or features of the cap  28  to denote which mode of operation of the radio  16  is active. In the various embodiments of the present invention, the stop cam  20  is held in a fixed position relative to rotary switch  14 . For example, as shown in  FIG. 2 , the switch stem  12  can extend through an opening  19  of the chassis  17  and through the stop cam  20 . The stop cam  20  can then be secured in place by a switch nut  29  holding the stop cam  20  in place against the chassis  17 . The mode indicator  23  can then be seated on top of the stop cam  20  and the switch nut  31 . The remainder of the knob assembly  10  can then be attached to the extending end of the stem  12 . 
   The switch stem  12  can be inserted into a stem opening  34  in the knob core  18 , thus fixing an axial position of the knob core  18  relative to the switch body  13  and the stop cam  20 . That is, a position of the switch body  13 , the stop cam  20 , and the knob core  18  are fixed with respect to a longitudinal axis  32 . The fastener  21  can be used to couple the knob core  18  to the switch stem  12 . For example, as shown in the  FIG. 3 , a fastener slot or hole  30  can be provided for inserting the fastener  21  and securing the knob core  18  to the switch stem  12 . In the embodiment in  FIG. 3 , the fastener hole  30  comprises a threaded hole for accepting a threaded fastener  21 . Although a screw-type or threaded fastener is shown in  FIGS. 2 and 3 , the present invention is not limited in this regard. In the various embodiments of the present invention other types of fasteners and fastening methods can be used. For example, in some embodiments, retention clips or pins can be used. In other embodiments, the knob core  18  can be pressure fit, glued, welded, or otherwise temporarily or permanently fastened to the switch stem  12 . In these alternate embodiments, the type, size, and shape of the fastener slot  30  can be adjusted as needed. 
   In the various embodiments of the present invention, the knob core  18  is configured to fit within the knob collar  22 , as further shown in  FIGS. 6A and 6B . In the various embodiments of the present invention, the knob core  18  and the knob collar  22  include mating features to keep a rotational orientation of the knob core  18  and the knob collar  22  fixed relative to each other. That is, to cause the knob core  18  and the knob collar  22  to rotate together. For example, as shown in  FIG. 5A , the knob core  18  can include inner mating features  60 , shown as rails. As most clearly shown in  FIG. 4B , the knob collar  22  can include matching outer mating features  62 , shown as grooves. The combination of grooves and rails also defines an axial displacement allowed for the knob collar  22  relative to the knob core  18 , as described below. However, the invention is not limited in this regard and other types and combination of the mating features can be used. 
   To couple the knob core  18  to the knob collar  22 , the knob core  18  can also include a knob stem  33  configured to extend through a bore  54  in the knob collar  22 . The knob stem  33  can include a groove or slot  58  for attaching clip  26  to secure the knob core  18  within the knob collar  22 . As shown in  FIG. 6A , the knob collar  22  can also receive the spring  24  and washer  25 , which encircle the knob stem  33  inserted through the bore  54 . Thus, after clip  26  is inserted into the slot  58 , the clip  26  retains the spring  24  and washer  25  in position within the knob collar  22 . Once the clip  26  is inserted, the spring  24  bears against the knob collar  22  and pushes or biases the knob collar  22  towards the stop cam  20 , as shown in  FIG. 6A . Consequently the knob collar  22  can only be displaced relative to the stop cam  20  by exerting a force on the knob collar  22  to compress spring  24 , as shown in  FIG. 6B . In the various embodiments of the present invention, stop cam  20 , the switch stem  12 , the knob stem  33 , and the bore  54  are oriented along a same longitudinal axis  32 . Therefore any force exerted on the knob collar  22  to compress spring  24  results in an axial displacement of the knob collar  22  along the longitudinal axis in a direction opposite to the force exerted by spring  24 . 
   In the exemplary embodiments in  FIGS. 2 ,  3 ,  6 A, and  6 B, spring  24  is shown as comprising a wave or crest-to-crest type spring. However, the present invention is not limited in this regard. In other embodiments of the present invention, the spring  24  can comprise any type of compression spring, including, but not limited to straight compression springs, concave compression springs, conical or spiral compression springs, and barrel compression springs. Furthermore, the spring  24  can have open or closed ends. The ends of the spring can also be ground, squared, or both. In the illustrated embodiment in  FIGS. 2 ,  3 ,  6 A, and  6 B, a wave spring is used to reduce the size of the knob assembly  10 , as a wave spring provides an higher stiffness than other types of compression springs having similar overall dimensions. 
   As shown in  FIGS. 1-14 , the stop cam  20  has a lower stop member  31  and the knob collar has upper stop members  46  and  48 . The lower stop member  31  and the upper stop members  46  and  48  are used to control rotation in the knob assembly  10  and to prevent inadvertent repositioning of the rotary switch  14  to an off or reset position. In particular, the lower stop member  31  and the upper stop members  46  and  48  are positioned at a same radius relative to the longitudinal axis  32  when the knob assembly  10  is mounted on the rotary switch  14 . Accordingly, then the knob collar  22  rotates, upper stop members  46  and  48  travel along a circumferential path with respect to the longitudinal axis. When the knob collar  22  is biased towards the stop cam  20 , the lower stop member  31  also lies in the circumferential path of upper stop members  46  and  48 . Consequently, the rotation of the inner and knob collars  18 ,  22  (and thus the switch stem  12 ) relative to the stop cam  20  is prevented or limited by features of the lower stop member  31  engaging with features of upper stop member  46  or upper stop member  48 . In the exemplary embodiment in  FIGS. 1-14 , the stop members are configured to have facing surfaces that engage when the inner and knob collars  12 ,  22  are rotated. However, the present invention is not limited in this regard and other type of features can be provided. For example, the stop members  31 ,  46 , and  48  can include interlocking features or geometries to enhance engagement of the stop members  31 ,  46 , and  48 . Additionally, although the lower stop member  31  is shown to extend in a direction opposite to the direction of upper stop members  46  and  48 , the invention is not limited in this regard. In the various embodiments of the present invention, the stop members  31 ,  46 , and  48  can extend in the same or different directions as long as lower stop member  31  is in the circumferential path of upper stop members  46  and  48  when the knob collar is in the first axial position and lower stop member  31  is removed from the circumferential path when the knob collar  22  is in the second axial position. 
   To allow rotation of the inner and knob collars  18 ,  22  (and thus the switch stem  12 ) beyond the upper stop member  46  or upper stop member  48 , the upper stop members  46  and  48  and the lower stop member  31  can be dimensioned so that compression of the spring  24  provides a spacing X, as shown in  FIG. 6B  in the direction of longitudinal axis  32 . The spacing X removes the lower stop member  31  from the circumferential path of upper stop members  46  and  48  and the inner and knob collars  18 ,  22  can rotate without the lower stop member  31  engaging either of upper stop members  46  or  48 . Although the use of a single lower stop member  31  and two upper stop members  46  and  48  is shown in the exemplary embodiment in  FIGS. 1-14 , the present invention is not limited in this regard. In the various embodiments of the present invention, any number of upper stop members and stops can be provided, where the position and number of upper stop members and stops is based the type and number of switch positions for the switch body  13 . 
   Referring now to  FIGS. 7-14 , the operation of the switch assembly is described. Only the stop cam  20  and the knob collar  22  are shown in  FIGS. 7-12  for ease of illustration and description. As previously described, the switch stem  12  in  FIGS. 1 and 2  can be rotated to one or more selected switch positions to place the radio  16  in different modes of operation. Furthermore, as previously described, the radio  16  can also include one or more switch positions that are not desired during normal operation of the radio. For example, during normal operations, a user will typically not wish to reset the radio  16  or turn off the radio  16  until the end of communications. In some cases, the user can wish to leave the radio  16  operating even if the radio  16  is not actively being used for communications. Accordingly, inadvertent switching to such non-preferred switch positions needs to be prevented or eliminated. Typically, these non-preferred positions are located at far switch positions of the rotary switch  14 . That is, at the first or last switch positions of the rotary switch  14 . Additionally, a user may also wish to prevent the radio  16  from being inadvertently activated, in which case, the other positions of the rotary switch  14  become non-preferred. In either case, the various embodiments of the present invention prevent or limit the rotary switch  14  from switching to positions generally not preferred by a user. 
     FIGS. 7 and 8  are side views of the arrangement of the knob collar  22  and the stop cam  20  in  FIG. 1  for a first position of the rotary switch  14  in  FIG. 1 . For ease of illustration and description of  FIGS. 7-14 , the rotary switch  14  of the radio  16  is assumed to have a first or off position, one or more second or channel positions, and a third or reset position.  FIG. 7  shows the arrangement of the knob collar  22  and the stop cam  20  in the off position prior to exerting force on the knob collar  22 . As upper stop member  46  and lower stop member  31  are positioned along the same circumferential path, no axial spacing between upper stop member  46  and lower stop member  31  is provided. As previously described with respect to  FIG. 6A , rotation of the knob collar  22  in direction Z is prevented by the upper stop member  46  engaging with the lower stop member  31 . Therefore, any inadvertent rotation from the off position to one of the channel positions is prevented. Instead, to allow rotation in direction Z, a force can be exerted on knob collar  22  to axially displace knob collar  22  in direction Y, as previously described with respect to  FIG. 6B , where Y is parallel to longitudinal axis  32 . The force in direction Y overcomes the force exerted by spring  24  to provide the spacing X, as illustrated in  FIG. 8 , needed for rotating knob collar  22  (as well as knob core  18  and switch stem  12 ) in the direction Z without upper stop member  46  engaging with lower stop member  31 . 
   In the various embodiments of the present invention, the force in direction Y needs to be maintained until upper stop member  46  clears lower stop member  31 . For example,  FIG. 9  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  in between an off position and a first channel position of the rotary switch in  FIG. 1  during rotation of the knob collar according to an embodiment of the present invention. As shown in  FIG. 9 , as knob collar  22  is rotated in direction Z, the force in the Y direction is needed to continue to axial displace knob collar  22  and maintain spacing X. Once upper stop member  46  clears lower stop member  31 , the force in the Y direction is not longer needed for further rotation in direction Z. This is illustratively shown in  FIG. 10 .  FIG. 10  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for a first channel position of the rotary switch in  FIG. 1 . 
   In the various embodiments of the present invention, the rotary switch  14  can include multiple channel or operational positions. Typically switching being channel positions is acceptable to the user and the user may wish to select different channels quickly and easily without having to exert a force other that a rotational force. That is, once the lower stop member  31  is no longer in the path of upper stop member  46 , knob collar  22  can be rotated in direction Z without force in the Y direction. However, lower stop member  31  also remains in the path of upper stop member  46  when attempting to rotate in a direction opposite to the Z direction. Therefore, lower stop member  31  also prevents the user from inadvertently switching to the off position without exerting force in the Y direction. Thus to switch to the off position, the steps shown in  FIGS. 7-10  can be repeated for rotating in a direction opposite to the Z direction. 
   In the embodiment of the present invention shown in  FIGS. 7-14 , the knob collar  22  can be rotated in the Z direction without exerting force in the Y direction until upper stop member  48  engages with lower stop member  31 , as shown in  FIG. 11 .  FIG. 11  is a side view of the arrangement of the knob collar and the stop cam in  FIG. 1  for a last channel position of the rotary switch in  FIG. 1 . As shown in  FIG. 11 , lower stop member  31  also prevents the user from inadvertently switching from the last channel position to the reset position, as previously described in  FIGS. 7 and 10 . That is, since upper stop member  48  and lower stop member  31  are positioned at the same radius and no spacing between upper stop member  48  and lower stop member  31  is provided, as previously described with respect to  FIGS. 6A and 6B , rotation in direction Z is prevented by the upper stop member  48  engaging with the lower stop member  31 . Accordingly, a similar procedure, as described above for  FIGS. 7-10  is followed for switching from the last channel position to the reset position (and vice versa). 
   First, a force is exerted in the Y direction, as shown in  FIG. 12 .  FIG. 12  is a side view of the arrangement of the knob collar  22  and the stop cam  20  in  FIG. 1  for the last channel position of the rotary switch  14  in  FIG. 1  after axial displacement of the knob collar  22  according to an embodiment of the present invention. As previously described for  FIG. 8 , sufficient force in direction Y is provided to overcome the force exerted by spring  24  to provide spacing X. Afterwards, as shown in  FIG. 13 , the knob collar  22  can be rotated while exerting force in the Y direction.  FIG. 13  is a side view of the arrangement of the knob collar  22  and the stop cam  20  in  FIG. 1  in between an the last channel position and a reset position of the rotary switch  14  in  FIG. 1  according to an embodiment of the present invention. As shown in  FIG. 13 , as long as force is exerted in the Y direction, at least a minimum spacing X is maintained and the knob collar can be rotated in the Z direction without upper stop member  48  engaging with lower stop member  31 . Finally, once upper stop member  48  clears lower stop member  31 , the force in the Y direction is no longer needed to place the rotary switch  14  in the reset position, as shown in  FIG. 14 .  FIG. 14  is a side view of the arrangement of the knob collar  22  and the stop cam  20  in  FIG. 1  for the reset position of the rotary switch  14  in  FIG. 1  according to an embodiment of the present invention. As previously described in  FIG. 10 , lower stop member  31  is now in the path of upper stop member  48  when attempting to rotate in a direction opposite to the Z direction (from a reset position to a channel position). Therefore, lower stop member  31  also prevents the user from inadvertently switching to a channel position without exerting force in the Y direction. Thus to switch from the reset position, the steps in  FIGS. 11-14  can be repeated for rotating in a direction opposite to the Z direction. 
   While the invention has been described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.