Rotary on/off switches are used in a variety of communication devices to provide a user interface for controlling operational functions such as power on/off, volume, and channel change, to name a few. For power on/off applications, the rotary switch may be designed to provide tactile feedback in the form of a click, or snap, to indicate that the switch has turned on or off. The switch may further provide a certain amount of torque, or frictional resistance, as the switch is rotated.
The tactile feedback provided by a rotary on/off switch is particularly important for portable communication devices operating within a public safety environment. For example, in public safety environments involving fire rescue, paramedic and/or law enforcement, a handheld radio may be operated by a user wearing heavy gloves, working in an area with little or no illumination, or other environmental or physical condition that necessitates a simple, easy to interpret user interface. As such, in the public safety arena, a communication device that offers a “single-click” feedback is often required. However, several design challenges are associated with the implementation of a single-click rotary on/off switch.
Certain rotary switches, such as those utilized in public safety applications, are designed to operate over a rotation range greater than 180 degrees. While the greater than 180 degree rotation provides more range with which to control such functions as volume, the single click is still required for public safety applications. To generate the single click, the rotary switch is typically limited to a single detent (bump). However the single detent presents additional implementation issues as discussed below.
A problem associated with the single click on/off switch is limited torque capacity. Rotary on/off switches which are required to rotate more than 180 degrees are limited, as previously discussed, by the single detent. The torque generating capacity of the single detent switch is fundamentally limited as a single detent provides less friction, and ultimately results in low torque.
Another problem associated with current day on/off rotary switches is the propensity for an unbalanced condition. Rotary on/off switches which are required to rotate more than 180 degrees are limited by the single detent as discussed above. When actuating the single click switch, the single detent results in unbalanced forces. These unbalanced forces make the implementation of such a switch very sensitive to spatial clearance limitations. The unbalanced design may potentially cause high stresses and moments on internal switch components.
Hence, the challenges of designing a rotary on/off switch for single click applications include single detent limitations, limited torque capacity and unbalanced design conditions.
Accordingly, there is a need for an improved on/off rotary switch which can overcome the aforementioned problems.
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.