Patent Application
20130125678
The present invention relates generally to a plunger mechanism, and more particularly to a plunger mechanism for increased torque and improved tactility for a switch used in a communication device.
Communication devices, such as two-way radios, often include at least one rotary control knob for controlling such operational features as volume adjustment and channel change. When operating in ruggedized environments, for example public safety environments, a communication device with a good user interface with strong tactile feedback is highly desirable. Users working in public safety environments often carry the device at their side on a belt clip, which requires the user to control knobs and switches without actually looking down at the device. In some applications, the control knobs and switches need to be accessible by users wearing gloves and/or working under noisy and high temperature conditions. A rotary control with a strong user interface is of particular importance in these environmental conditions.
Rotary controls have utilized ball plunger mechanisms in the past to increase torque and improve tactile feedback. However, common off-the-shelf ball plungers utilize springs and materials that can incur decreased performance and deformation after life-cycling and continued on/off usage. Ball plungers can also require lubrication especially in rotary applications which adds potential contamination, complexity, cost, and leads to potential parts degradation.
Additionally, several manufacturing related issues can arise with the use of ball plunger mechanisms including ball captivation problems wherein retention features are inadequate causing that ball to fall out. Unwanted “clicks” may occur when actuating a loose ball and barrel.
Accordingly, there is a need for an improved plunger mechanism that can be applied in switch applications, such as rotary control applications in communication devices.
The accompanying figures where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in apparatus components providing a purely mechanical-based solution to illuminating a control knob, thereby eliminating the cost associated with the software and electrical approaches.
Accordingly, the apparatus components and method steps have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
Briefly, there is provided herein a plunger mechanism for use in a rotary control switch which provides increased torque and tactile feedback. The plunger mechanism provides an improvement over past complex ball plungers by being lower cost, less complex, and readily manufacturable. The improved plunger mechanism is highly adaptable to applications that require a small drop-in solution to add force/torque or tactility. The plunger mechanism is highly suitable to applications in which products are exposed to high-temperature and harsh-environments. Products, such as communication devices operating within a public safety environment, can benefit from the increased torque and tactility of a rotary switch incorporating the improved plunger mechanism.
In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
The sleeve is made from a low-compression set material, such as silicone or other rubber of suitable durometer or hardness depending on the application. For environmentally harsh conditions, the sleeve material may be selected to be resistant to chemical corrosion, high-temperature, and life-cycle wear. Depending on the application, the sleeve material may also be made from a natural lubricant material, such as oil bleeding silicone, low coefficient of friction liquid injection molding (LIM), or compression molded silicone, to name a few.
Depending on the desired amount of torque, a backer element 110 may be coupled to one end of the sleeve to provide an increased surface area for compression of the second end 106 of plunger 102. The stiff backer element 110 may be made of a rigid plastic such as glass filled polycarbonate or the like. The backer element material should be selected to provide adhesion to the sleeve 108. The silicone sleeve 108 bonds to the backer element 110 during the molding process. Since the materials are selected for natural adhesion during the molding process, no glue is required in the formation of plunger mechanism 100.
For applications in which a backer element 110 is not needed or desired, the sleeve 108 is simply molded over the second end 106 of plunger 102.
The plunger is made of a hard material which provides resistance to corrosion, such as a stainless steel metal or very rigid plastic. The metal may be polished to provide, depending on the application, improved wear resistance and smooth function. The first end 102 operates as a plunger tip and its half spherical shape provides the necessary feedback where interacting with a mating part. The dimensions (length, diameter, width, depth) of the plunger 102 are dependent on the application. The plunger may be solid for increased weight and torque, or hollow to provide decreased weight in lighter applications. For example deep draw steel sheet metal could be used for a lighter application, and 440C hardened stainless steel could be used for a heavier application. The plunger mechanism 100 does not require the use of a spring or ball bearing making it easy to manufacture and assemble.
While a pre-made sleeve might be used instead of the overmolded sleeve 108, a premade sleeve is far less desirable as it involves more assembly, lack of adhesion and risk of loose parts. Using the overmolded sleeve 108 to form the plunger mechanism 100 is far more desirable as the adhesion properties provide for an improved drop-in component that eliminates loose individual piece parts, as will further be shown and described in conjunction with
As mentioned previously, for applications in which a backer element 110 is not needed or desired, the sleeve 108 would simply be molded over the second end 106 of plunger 102.
The plunger mechanism 100 provided by the various embodiments is highly adaptable to applications that require a small drop-in solution to add force/torque or tactility. The plunger mechanism 100 is highly suitable to applications in which products are exposed to high-temperature and harsh-environments. Unwanted clicks and other captivation issues can now be avoided as the use of a ball and spring has been eliminated. The plunger mechanism 100 provides a drop-in component for increasing on/off detent without adding complexity to a switch as will be described in conjunction with
Referring to
As a practical example, a plunger formed of 440C solid stainless steel having approximate dimensions of 6.5 mm in length, 205 mm in width has been incorporated has been implemented to provide a torque value of 6-12 inch-ounces.
As the rotary control 402 is rotated via knob 406, the detents 408 hit the half-spherical tip 104 of the plunger mechanism 100 at a predetermined point of rotation. As the detents 408 hit the half-spherical tip 104 the compression and decompression of the plunger mechanism 100 riding over the detents 408 provides increased torque and tactility feedback. As the rotary control 402 is turned, the detents 408 rotate, each detent providing resistance by which the plunger is compressed into the cylindrical recess 410—thus providing rotational torque for a stiff on-off or transitional stage tactile feedback. The remainder of rotation may or may not include detents depending on the application.
For example, a rotary control used in volume adjustment may only utilize a single tooth gear in conjunction with the ball plunger mechanism 100 to provide on/of torque. In another example, a rotary control used for frequency/channel change options may utilize a multi-tooth gear in conjunction with the ball plunger mechanism 100 to provide stiff torque at each channel change transition. The same plunger mechanism 100 is thus readily suited to many switch applications. A harder detent action can now be achieved by the incorporation of plunger mechanism 100 without impacting the function of the switch.
Accordingly, an improved plunger mechanism 100 has been provided which is highly adaptable to applications that require a small drop-in solution to add force, torque and tactility. This drop-in approach eliminates the need for any springs thereby lowering cost and facilitating assembly. Unwanted clicks and other captivation issues incurred by previous ball plunger type approaches can now be avoided. The plunger mechanism 100 is particularly useful in rotary control applications requiring an easily discernable on/off switch or other functional transition switch. The highly resistant plunger mechanism 100 increases torque and tactility thereby providing an improved user interface for a communication device operating under harsh-environments, such as high temperature, corrosive and/or noisy environments.
In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
