Traditionally, mechanical devices have been used to latch and unlatch closures such as doors, trunks, hoods, lift gates and hatches and the like in automobiles and other vehicles. It is known, however, to utilize an electro-mechanical door latch mechanism for such applications for a variety of reasons including ease of operation, lower cost and weight, improved styling opportunities, and reduced complexity. For example, a user actuated switch can be employed to trigger the release of a mechanical latch. In this regard, an electrical switch is operable to provide an input to a controller for operating the mechanical latch when the switch is actuated. In addition, modern styling and ergonomic requirements may dictate the physical configuration of the switch. For example, the switch may need to comprise an aesthetically pleasing user actuation component (e.g., a low profile button) that is of adequate size and shape so as to be easily operated by a user under a wide variety of operating conditions in a wide variety of environments.
Known switch technology for such applications generally incorporates a button having a first electrically conductive material comprising protrusions having the shape of “pills” or spring-like “fingers” that are insert molded or otherwise attached to the underside of the button. A second electrically conductive material comprising a set of contacts is located opposite the button on a base portion of the switch assembly. The second electrically conductive material may typically be in the form of a plate, tracks or a printed circuit board, for example. The first electrically conductive material completes a circuit in the switch when the switch is actuated by depressing the button. For example, when the button is depressed, the first conductive material bridges the contacts of the second electrically conductive material thereby closing an electric circuit.
In one such known switch assembly configuration, the switch assembly is also sealed from the atmosphere. During its manufacture, a fixed volume air is captured in the space between the button and the base portion of the switch assembly. As such, when the ambient temperature of the switch assembly changes, so too does the volume of the air trapped within the switch assembly. Under hotter ambient temperature conditions the volume of air within the switch assembly expands; under colder ambient temperature conditions, the volume of air within the switch assembly contracts.
In such a design, changes in the switch assembly's operating environment, such as extreme changes in ambient temperature, for example, can impact the perceived operation of the switch to a user. For example, the switch assembly may not reliably provide satisfactory and perceptible tactile feedback to the user signifying actuation of the switch. In such a case, depression of the button may instead provide an unsatisfactory continuous resistance to the user causing the user to be unsure whether the switch has been properly actuated.
Consequently, it is desirable to provide a switch assembly having a reliable and cost-effective actuation mechanism that also provides satisfactory tactile feedback to a user for signifying proper actuation of the switch.