Abstract:
The panel mounted low profile rotary switch ( 170, 300 ) includes a knob ( 175, 210, 305 ), a detent subassembly ( 180, 220 ), a shaft ( 255, 365 ), a bushing ( 185, 260, 355 ) and a panel ( 197 ). The knob is simply held to the shaft by one or more locking screws ( 177 ) and the operation of the detent sub-assembly is not altered by removal of the knob. The entire detent sub-assembly is located on the knob side or user&#39;s side of the panel. Only the bushing and the shaft extend through the panel. The shaft is connected to a rotary component such as a rotary switch contact ( 265, 372 ) which engages circuitry on a printed circuit board ( 374 ). The switch or electrical connection is located on or juxtaposed to the undersurface of the panel

Description:
[0001]     This application claims the benefit of U.S. provisional application No. 60/407159 filed on Aug. 29, 2002 incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The field of the invention is electromechanical rotary switches.  
       BACKGROUND OF THE INVENTION  
       [0003]     A rotary electromechanical switch is generally defined as a device that has a rotating shaft connected to one terminal capable of making or breaking a connection to one or more other terminals. A rotary electromechanical encoder includes the overall characteristics of a rotary switch, but has additional mechanical movements. In any case, a user typically manipulates the switch to manually select a circuit.  
         [0004]     Rotary switches and encoders are often mounted upon panels and other supporting structures in order that a user may control an electrical device. It is common for a portion of the switch to be on one side of the panel (the user side) and another portion of the switch to be on the other side of the panel (the inside). In many instances, the only portion of a switch that is on the user&#39;s side of the panel is a section of the shaft and a knob or other actuating means. Generally, the bulk of the switch is on the inside of the panel. For many years this type of configuration was sufficient, but over time the size of electrical devices has become increasingly smaller and there has become a need to reduce the size of the switch—especially that portion on the inside of the panel.  
         [0005]     In order to meet the needs of smaller devices having less room under the panel, the size of the components of the switches have also become smaller. Yet, because these switches are comprised in part of mechanical components, there remained a practical limit as to how small they could become while still remaining useful. There became a need for different designs rather than just a reduction in the size of the components. One such design is taught in U.S. Pat. No. 4,454,391 to Olsson (June 1984). Olsson describes a low profile dip switch used on an integrated circuit board in which the actuating member of the dip switch is set within the body of the switch. By reducing the vertical profile of the switch, a lower overall footprint may be achieved for a board. The switch design taught by Olsson, however, does not address design problems related to panel mounted switches. Another patent which addresses problems in the design of switches is described in U.S. Pat. No. 6,312,288 to Genz et al. (November 2001). Genz teaches a low profile combination switch and connector assembly. While the switch described by Genz may have resulted in a lower overall profile of the combined components, this switch still does not address problems of panel mounted switches, specifically those problems due to limited space under the panel.  
         [0006]     U.S. Pat. No. 6,043,855 to Grave (March 2000) is directed toward switches that mount on a bezel surrounding an LCD which is located on an avionics panel in an aircraft. The &#39;855 patent teaches a design in which the detent is at least partially positioned in the knob of the switch. Still, the design of the &#39;855 patent has its shortcomings: the detent is housed by the knob such that if the knob were to be displaced, the switch would not function or would function improperly; the detent is not entirely within the knob; the design requires two springs; and the springs are mounted vertically adding to the overall vertical profile of the knob.  
         [0007]     As electronic devices become even smaller, there is a need for more compact designs and designs which have less dependence on the knob.  
       SUMMARY OF THE INVENTION  
       [0008]     The inventive subject matter is a low profile switch having a detent mechanism on the outside of a panel on which the switch is mounted. The switch has a single substantially horizontal spring as part of the detent mechanism, and the detent sub-assembly is substantially covered by the knob.  
         [0009]     Another aspect includes devices and methods of use in which the switch operates independently of the knob.  
         [0010]     Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1   a  is a prior art rotary switch.  
         [0012]      FIG. 1   b  is a cross-sectional view of a rotary switch.  
         [0013]      FIG. 2  is a perspective view of a partially exploded rotary switch.  
         [0014]      FIG. 3  is a perspective view of a fully exploded rotary switch.  
         [0015]      FIG. 4  is a perspective view of a rotary switch that is mounted on a panel having a round hole. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Referring first to  FIG. 1   a , a prior art rotary switch  100  comprises a detent mechanism  110 , a knob  120 , springs  130 , balls  140 , a shaft  150 , and a panel  160 .  
         [0017]     The detent mechanism  110  is comprised at least partially of springs  130  and balls  140 . It should be noted that there are two springs  130  and each spring is housed in a channel in the knob  120 . Because the springs are housed in the knob, the operation of the detent sub-assembly is dependent on the knob. It should also be noted that the springs  130  are elongated in a dimension parallel to the shaft. Yet another notable feature of the prior art switch is the extension of the detent mechanism  110  into the panel.  
         [0018]      FIG. 1   b  depicts a rotary switch  170  generally comprised of a knob  175 , a detent sub-assembly  180 , a bushing  185 , and a panel  197 .  
         [0019]     A comparison of  FIG. 1   b  with  FIG. 1   a  emphasizes at least two notable distinctions between the two switches depicted. The first distinction is that the prior art switch is dependent upon the knob  120  for housing of the detent  110  and for operation of the switch. The second distinction is that the detent of the prior art switch extends into the panel. Other distinctions exist such as the position of the spring and the quantity of springs.  
         [0020]     With regard to the first distinction, prior art dependence on the knob is caused by a design in which the detent is housed within the knob. In the present subject matter, the detent sub-assembly is fully enclosed independent of the knob (i.e. not housed in the knob). The knob  175  is simply held to the shaft by one or more locking screws  177 , and the operation of the detent sub-assembly  180  is not altered by removal of the knob  175 .  
         [0021]     Addressing the second distinction,  FIG. 1   a  depicts the extension of the detent sub-assembly into the panel. This extension is problematic because additional work is required to prepare the panel to receive a switch. Conversely,  FIG. 1   b  shows that the entire detent sub-assembly  180  is on the knob-side of the panel  197 , and that only the bushing  185  and shaft (not shown—disposed in the bushing) extend through the panel.  
         [0022]     Focusing on  FIG. 2 , a partially exploded rotary switch generally includes a knob  210 , a detent sub-assembly  220 , a shaft  255 , a bushing  260 , and an electrical contact  265 .  
         [0023]     Knob  210  has a knob locking screw  212  that is used to hold the knob  210  to the shaft  255  which extends up through the panel  240  and through the detent sub-assembly  220 . A variety of different knobs are also contemplated including those that are sized and shaped different than the knob in  FIG. 2 . Alternative knob/shaft configurations are contemplated including a configuration in which two or more knob locking screws are used to hold the knob to the shaft. A preferred manner for altering the electrical connection established by the switch is by rotating the knob. Other manners for altering the connection include rotating the shaft directly and depressing the shaft and/or knob, at times in combination with rotation.  
         [0024]     A fully enclosed detent sub-assembly  220  has a detent cap  215  that functions to at least partially enclose the sub-assembly. As used with a detent sub-assembly, the term “fully enclosed” means that the spring and balls of the detent sub-assembly (or their functional equivalents) are held in their functional configuration by a component other than the knob. In  FIG. 2 , the detent sub-assembly  220  is held in its functional configuration by the sprocket  217  and the cap  215 . As noted above, a fully enclosed detent sub-assembly is independent in that the functional aspect of the detent does not need the knob to operate effectively.  
         [0025]     The operation of a rotary switch may be described with reference to  FIG. 3 , which is a view of a fully exploded rotary switch according to one embodiment. The depicted rotary switch  300  generally comprises a knob  305 , a detent sub-assembly, a bushing  355 , a shaft  365 , an electrical contact  372 , and a printed circuit board (PCB)  374 .  
         [0026]     A knob  305  fits onto a shaft  365  by means of a split in the shaft  365 . A knob locking screw  307  (or a plurality of knob locking screws) may optionally secure the knob  305  to the shaft  365 . A preferred knob contains a blade (not shown) designed to contact stop pins  310  and limit the rotation of the switch. With respect to stop pins, it is generally contemplated that a pin or pins extend from the detent sprocket up through the detent cap into the enclosure formed by the knob. In a preferred embodiment, stop pins engage a knob blade and limit the rotational travel of the switch. It should be appreciated, however, that the switch can operate without stop pins.  
         [0027]     The detent sub-assembly in  FIG. 3  is comprised of a sprocket  326  having cylindrical lobes  328 , a rotor  324 , a spring  320 , balls  322 , and a cap  315 . The rotor  324  is supported by a ridge or shelf (not shown) on the sprocket  326  and the bushing  355  extends substantially up to the ridge, but does not contact the rotor  324 . The general operation of a detent sub-assembly is similar to that of known detents in that switch positions are established by the detent rotor rotating about the cylindrical lobes of the sprocket. In a preferred class of embodiments, the detent sub-assembly comprises a single spring that is horizontally disposed inside the rotor and positioned through the slot of the shaft. The spring loaded balls  322  extend at least partially through holes  325  of the rotor  324 .  
         [0028]     With regard to the operation of switch  300 , the shaft  365  rotates in the interior cavity of the threaded bushing  355  and effects a rotational alignment between the knob  305 , the detent rotor  324  and the electrical contacts  372 . Rotation of the shaft  365  causes the rotor  324 , the spring  320  with its associated balls  322 , and the electrical contacts  372  to also rotate—the balls  322  rotating about the inner surface of the sprocket  324  (i.e. the cylindrical lobes  328 ) and the electrical contacts rotating about the PCB. The spring  320  provides sufficient pressure to effect an appropriate rotational torque of the switch.  
         [0029]     Sprocket  326  is held relatively stationary (i.e. does not rotate) by the resistance provided by locking screw  329  against bushing  355 . In other embodiments, a bushing can have two (or more) flat sides (a double flat sided bushing). The double flat sided bushing can extend up through a hole in the panel that approximates the shape of the double flat sided bushing. Additionally, the sprocket  326  can have two locking screws, each locking screw cooperating with a flat side of the bushing to provide additional resistance to rotation.  
         [0030]     Electrical contacts  372  (e.g. switch wipers or brushes) are mounted on a non-conductive disc  370  (i.e. dielectric) and the contacts  372  cooperate with the circuit configuration on the PCB  374 . The PCB  372  is anchored to the threaded bushing  355  by metal rivets  380  or other connectors, however it should be noted that anchoring of the PCB to the bushing is not a requirement. Although not depicted, a PCB can contain additional electronic components (e.g. chips, pins, leads, and so forth) that may interface with components other than the switch. Setting of a switch position, therefore, is generally a function of the interaction among the detent sub-assembly, the shaft, the electrical contact and the PCB. An electrical signal is transmitted through output pins  375 . Of course, an electrical signal may travel through other known connectors and the signal may be converted and transmitted wirelessly.  
         [0031]     A capture nut  335  and associated lock washer  340  advantageously function to affix a switch to a panel  345  when the nut  302  is threaded to the bushing  355 . A sealing gasket  350  and sealing o-ring  360  along with the panel  345  all function to substantially seal the inner workings under a panel (the underside of a panel) from outside contamination caused by moisture, tampering, etc. A panel may be necessary to preserve the safety of a user and the operational integrity of a device. The degree of insulation that a panel provides is at least partially a function of the material that the panel is made from and the degree to which the panel is sealed. For example, the panel depicted in  FIG. 3  is made from aluminum and is sealed by gasket  350  and sealing o-ring  360 , in combination with panel  345 , bushing  355 , and slot  369 .  
         [0032]     It may be important to maintain consistent pressure between electrical contacts  372  and PCB  374 . For this reason, a preferred rotary switch limits axis travel of the shaft. One way of doing this is to create a resistance to axial movement by fitting retaining ring  330  into slot  367 .  
         [0033]     Turning now to the configuration of panel  345 , it should be noted that hole  347  in panel  345  is “D” shaped in order to prevent bushing  355  from rotating as the shaft  365  is rotated. Another way of preventing rotation of the bushing is depicted in  FIG. 4 . As depicted, a “D” shaped non-turn washer  420  is used in combination with a panel having two holes  412 , and  414 . The larger hole  412  is substantially round and is sized to accept the shaft and the upper portion  430  of the bushing  260 . The smaller hole  414  accepts tab  422  of non-turn washer  420  and thereby inhibits rotation of the bushing  260 . For purposes of sealing, the hole that accepts the tab may protrude only partially into the panel, rather than through the panel. A further contemplated class of embodiments limits rotation by means of a pin that extends from the base of the bushing  432  into the panel.  
         [0034]     Thus, specific embodiments and applications of a low profile switch have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.