Patent Publication Number: US-6660947-B1

Title: Method and apparatus for push-button control

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to push-button control knobs, and more particularly to a method and apparatus for providing rotational and axial control using a push-button control knob. 
     Control knobs are used on a variety of different devices, perform a variety of different functions and are typically used for controlling automotive systems, such as a radio, for example. Some control knobs have a rotational degree of freedom (rotary type), and have been used to control the volume of an audio system, and others have a translational degree of freedom (slide arrangement), and have been used to control the tone (bass and treble for example) of an audio system. Other control knobs have both rotational and axial (push-button type) degrees of freedom, and have been used to control both the volume and channel balance of a stereo audio system. Multi-functional control knobs provide a degree of convenience for the operator of the controlled device since the operator need only locate one control knob in order to perform more than one function. Push-button-rotary combination control knobs typically employ a control shaft that has both rotational and axial degrees of freedom, thereby requiring a special coupling between the control shaft and the controlled device. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, a push-button control knob having rotational and axial degrees of freedom includes a housing having a first end, a second end, and an integrally arranged hub and rim disposed between the first and second ends. The hub has a central hole and the rim has a plurality of through-holes. An actuator assembly is disposed within the housing and a bias spring is disposed between the housing and the actuator assembly for biasing the actuator assembly in a first direction. 
     In another embodiment, a method for assembling a push-button control knob having rotational and axial degrees of freedom includes selecting a first actuator plate, grounding the first actuator plate in an orientation in preparation for assembly, selecting a housing in an orientation in preparation for assembly, aligning the axes of the housing and the first actuator plate, assembling the housing onto the first actuator plate, selecting a bias spring in an orientation in preparation for assembly, aligning the axes of the bias spring and the housing, assembling the bias spring onto the housing, selecting a second actuator plate in an orientation in preparation for assembly, aligning the axes of the second actuator plate and the first actuator plate, assembling the second actuator plate onto the first actuator plate, wherein the bias spring is captured between the housing and the second actuator plate, and wherein the first and second actuator plates are coupled together. 
     In a further embodiment, a push-button control knob having rotational and axial degrees of freedom includes a housing grounded to a shaft and having a rotational degree of freedom, an actuator assembly disposed within said housing and having an axial degree of freedom, and a bias spring disposed between said housing and said actuator assembly for biasing said actuator assembly in a first direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the figures, which are exemplary embodiments, and wherein like elements are numbered alike: 
     FIG. 1 depicts a cutaway isometric view of an assembled push-button control knob in accordance with an embodiment of the invention; 
     FIG. 2 depicts a cross-section side view of the assembled push-button control knob of FIG. 1; 
     FIG. 3 depicts an isometric view of a cylindrical housing in accordance with an embodiment of the invention; 
     FIG. 4 depicts an isometric view of a first actuator plate in accordance with an embodiment of the invention; 
     FIG. 5 depicts an isometric view of a second actuator plate in accordance with an embodiment of the invention; 
     FIG. 6 depicts a process flowchart for assembling the push-button control knob of FIG. 1; and 
     FIG. 7 depicts an alternative embodiment of the assembled push-button control knob of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A detailed description of an embodiment of the present invention is presented herein by way of exemplification and not limitation with reference to FIGS. 1-7. 
     Referring to FIGS.  1  and  3 - 5 , a push-button control knob  10  includes a cylindrical housing  100 , a first actuator plate  200 , a second actuator plate  300 , and a bias spring  400 . In an embodiment, cylindrical housing  100  is cylindrically shaped, but cylindrical housing  100  may also be scalloped or ergonomically shaped. Cylindrical housing  100 , as best seen by referring to FIG. 3, includes a first end  102 , a second end  104 , a centrally located cylindrical hub  110 , an outer cylindrical surface that serves as a handle  120 , and a rim  130  that extends between and is integral with hub  110  and handle  120 . Hub  110  includes a central hole  140  that is preferably a blind-hole but may also be a through-hole. The shape of central hole  140  is a matter of design choice and may be circular or shaped, such as, for example, scalloped or “D” shaped. Rim  130  includes a plurality of through-holes  150 , where in one embodiment three through-holes  150 , spaced equidistant around rim  130 , are shown by way of exemplification and not limitation. First actuator plate  200 , as best seen by referring to FIG. 4, includes a central hole  210  that is surrounded by and defines a ring  220 . Integral with ring  220  are a plurality of hollow pegs  230  having blind-holes  240 . As seen in FIG. 4, an embodiment includes three hollow pegs  230  spaced equidistant around ring  220  and with axes parallel to the axis of central hole  210 . Second actuator plate  300 , as best seen by referring to FIG. 5, includes an actuator disc  310  and a plurality of pegs  320 , three shown, integral with and disposed around the perimeter of actuator disc  310 . As shown, the axes of pegs  320 , spaced equidistant around the perimeter, are parallel to the axis of actuator disc  310 . The preferred number of through-holes  150 , hollow pegs  230 , and pegs  320 , is three. However, any number of through-holes  150 , hollow pegs  230 , and pegs  320  may be used where the push-button control knob  10  functions as described herein. In an alternative embodiment, hollow pegs  230  may be eliminated and pegs  320  may be coupled (e.g., adhered or bolted) directly to ring  220  of first actuator plate  200 , thereby enabling push-button control knob  10  to function as described herein. In a further alternative embodiment, pegs  320  may be eliminated and hollow pegs  230  may be coupled directly to actuator disc  310 . In yet a further alternative embodiment, there may be more or less than three through-holes  150 , hollow pegs  230 , and pegs  320 , providing the push-button control knob  10  functions as described herein. 
     The assembly of push-button control knob  10  is best seen by now referring to the process  500  of FIG.  6  and the structures depicted by FIGS. 1 and 2. Referring to FIG. 6, process  500  begins by selecting  510  a first actuator plate  200  and then grounding  520  first actuator plate  200  on a working surface, such as a horizontal work bench (not shown), for example, in an orientation in preparation for assembly. An “orientation in preparation for assembly” refers to an orientation of a part that facilitates in-line or top-down assembly where the mating side of a first part faces the mating side of a second part. Regarding first actuator plate  200 , an orientation in preparation for assembly refers to ring  220  being supported by work bench (not shown) with hollow pegs  230  facing up (upstanding). 
     At step  530 , cylindrical housing  100  is selected and oriented in preparation for assembly. Here, cylindrical housing  100  is oriented with first end  102  facing down to face upstanding pegs  230 . To assemble cylindrical housing  100  onto first actuator plate  200 , not only must the axes of cylindrical housing  100  and first actuator plate  200  be aligned, but also the axes of through-holes  150  must be aligned with the axes of hollow pegs  230 . At the proper orientation, cylindrical housing  100  assembles onto first actuator plate  200  with hollow pegs  230  protruding through through-holes  150 . Central hole  210  of first actuator plate  200  is sufficiently sized to fit around hub  110 , thereby permitting the top surface  222  of ring  220  to abut the bottom surface  132  of rim  130  when first actuator plate  200  is pushed against cylindrical housing  100 . 
     At step  560 , a suitable bias spring  400  is selected and oriented in preparation for assembly. In an embodiment, bias spring  400  is a helical compression spring, but may also be a leaf spring or a wave spring, and is oriented with its axis aligned  570  with the central axis of cylindrical housing  100 . The outer diameter of bias spring  400  is appropriately sized to fit within the inner diameter defined by hollow pegs  230  of first actuator plate  200 , such that bias spring  400  can be assembled  580  onto cylindrical housing  100  and nested within upstanding hollow pegs  230 . Bias spring  400  may also be molded as an integral part of a molded second actuator plate  300 . 
     At step  590 , second actuator plate  300  is selected and then oriented such that pegs  320  face hollow pegs  230 . At step  600 , the axes of second actuator plate  300  and first actuator plate  200  are aligned. Also aligned are the axes of pegs  320  and hollow pegs  230 . The assembly of push-button control knob  10  is completed by assembling  610  second actuator plate  300  onto first actuator plate  200 , wherein pegs  320  are inserted into blind holes  240  of hollow pegs  230 . A press fit arrangement between pegs  320  and hollow pegs  230  ensures a secure assembly. Alternatively, pegs  320  may be adhered to hollow pegs  230  using a suitable adhesive, or first and second actuator plates  200 ,  300  may be adhered or bolted to each other. The coupled (e.g., press-fit, adhered, or bolted) arrangement of first actuator plate  200  and second actuator plate  300  is herein referred to as an actuator assembly  350 . 
     In the completed push-button control knob assembly  10 , depicted in FIG. 1, the press fit assembly of first actuator plate  200  and second actuator plate  300  (the actuator assembly  350 ) is free to slide axially relative to cylindrical housing  100  by virtue of hollow pegs  230  sliding within through-holes  150  of rim  130 . Bias spring  400 , which is captured between cylindrical housing  100  and actuator disc  310  of second actuator plate  300 , exerts a bias force “F” in the direction of arrow  12  (a first direction). The press-fit arrangement of the actuator assembly  350  is of sufficient strength to restrain bias spring  400  in its acquiescent state. When an operator pushes against actuator disc  310  to oppose bias force F (a second direction), bias spring  400  compresses to permit axial motion of actuator assembly  350 , and therefore axial motion of ring  220 , in the second direction. The rotational degree of freedom provided by cylindrical housing  100  and the axial degree of freedom provided by ring  220  can be used for multi-function control without requiring a special coupling between the control shaft and the controlled device, as will now be discussed in reference to FIG.  2 . 
     In FIG. 2, assembled push-button control knob  10  is depicted in a cross-sectional side view having a section cut parallel to and coincident with the central axis of knob  10 . A control shaft  700  is disposed within central hole  140  of hub  110  of cylindrical housing  100  during assembly of push-button control knob  10  to the controlled device (not shown). The assembly of knob  10  to shaft  700  is accomplished by aligning the axis of cylindrical housing  100  with the axis of control shaft  700  and assembling the central hole  140  of cylindrical housing  100  over the end  710  of control shaft  700  until cylindrical housing  100  is seated on control shaft  700 . Control shaft  700  is seated when end  710  abuts the inside end wall of blind central hole  140 . The end  710  of control shaft  700  is shaped to match the shape of central hole  140 , which, as discussed above, may be circular or shaped, such as, for example, scalloped or “D” shaped, thereby providing a means for imparting a torque to control shaft  700  when push-button control knob  10  is rotated. The shaft body  720  is connected to the controlled device (not shown) and is herein referred to as being grounded. 
     The securement of push-button control knob  10  on control shaft  700  may be accomplished by a press-fit arrangement or the use of a set screw  800 . If a set screw  800  is employed, the assembly of push-button control knob  10  requires the selection of a cylindrical housing having a trans-axial through-hole  160  that extends from an outer surface of cylindrical housing  100 , the outer surface of handle  120 , to the inner surface of central hole  140  of hub  110 . During assembly, a set screw  800  is selected, in an orientation in preparation for assembly, and then assembled into the trans-axial through-hole  160  of cylindrical housing  100 . Set screw  800  is then tightened to secure cylindrical housing  100  to control shaft  700 . 
     The assembly of push-button control knob  10  to control shaft  700  places knob  10 , and more particularly ring  220  of first actuator plate  200  of knob  10 , in close proximity to switch  850 , and more particularly to switch actuator  870 . Switch body  860  is connected to the controlled device (not shown) and is herein referred to as being grounded. 
     The completed assembly of push-button control knob  10  to the controlled device (not shown) has both rotational and axial degrees of freedom, thereby providing multi-functional control of the controlled device. The rotation of cylindrical housing  100 , via handle  120 , imparts a torque to control shaft  700 , and the depression of actuator disc  310 , opposing force “F” of bias spring  400 , imparts an axial force that is transmitted to switch actuator  870 , via ring  220  of first actuator plate  200 , for actuating switch  850 . When switch  850  is in an acquiescent state, not actuated, the rotation of shaft  700  has a first function, such as, for example, adjustment of the volume level of an audio system. When switch  850  is actuated, the rotation of shaft  700  has a second function, such as, for example, adjustment of the channel balance of a stereo audio system. The apparatus can also be used to navigate through a menu, where the rotation action is used to move between different functions at the same level in the menu and the switch is used to select the respective function. 
     An alternative embodiment, depicted in FIG. 7, includes a groove  106  in cylindrical housing  100  for accepting an O-ring  410  that is elastically contained within groove  106 . The O-ring  410  interacts with a mating surface of the controlled device (not shown) to provide for a waterproof arrangement when assembled. In addition to O-ring  410 , a flexible membrane  420  may be employed over the second end  104  of cylindrical housing  100  by stretching the flexible membrane  420  and attaching it to the outer edge  108  of cylindrical housing  100 . If cylindrical housing  100  and flexible membrane  420  are made of polymeric material, they may be attached using a heat staking process. The adhesion of flexible membrane  420  to outer edge  108  of cylindrical housing  100  provides for additional waterproof protection. Use of an elastomeric material for flexible membrane  420  will also provide a spring-like action, which could be used to bias second actuator plate  300  in the first direction by attaching flexible membrane  420  to second actuator plate  300 , thereby negating the need for bias spring  400 . O-ring  410  and flexible membrane  420  may be used singly or jointly, and provide not only waterproof protection, but also protection from contaminates and impurities. 
     As shown and discussed, and in accordance with an embodiment of the invention, multi-functional control of a controlled device is achieved without the need for a control shaft to have both rotational and axial degrees of freedom, thereby avoiding the need for a special coupling between control shaft  700  and the controlled device (not shown). Additionally, the axial motion of a centrally located actuator disc  310  does not require the cylindrical housing  100  to have space between itself and the front panel of the controlled device (not shown), thereby resulting in a lower profile push-button control knob  10 . Further, the use of a ring  220  on first actuator plate  200  provides for switch actuator  870  to be located off-axis for ease of assembly. 
     While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be 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.