Patent Application
20090178911
1. Field
The disclosed and claimed concept relates generally to handheld electronic devices and, more particularly, to a key dome assembly for a handheld electronic device, wherein the dome assembly includes micro structures which elevate the dome shaped element from a supporting surface.
2. Description of the Related Art
Numerous types of handheld electronic devices are known. Examples of such handheld electronic devices include, for instance, personal data assistants (PDAs), handheld computers, two-way pagers, cellular telephones, and the like. Many handheld electronic devices also feature a wireless communication capability, although many such handheld electronic devices are stand-alone devices that are functional without communication with other devices.
Such handheld electronic devices are generally intended to be portable, with many of such devices being small enough to fit within, for example, a pocket, a belt holster, a briefcase, or a purse. As the form factor of such devices has shrunk for improved portability, so has the size of components such as keyboards or keypads. The keyboards or keypads include keys that act as switches for input entry when actuated. In furtherance of miniaturization of keyboard assemblies such as keyboards and keypads, one general approach implemented by several different manufacturers has involved the use of an electrical key in the form of a resilient dome shaped element that is electrically conductive and is disposed on a circuit board.
In simplest form, such a dome assembly is a smooth sector of a hollow sphere. When an actuation force is applied to the apex of the dome assembly, the dome assembly collapses, completing an electrical circuit or at least an open portion of an electrical circuit of the device. The collapsing dome assembly provides a tactile feedback to the user of the handheld electronic device. Such simple sphere segments have been generally effective for their intended purpose; however they have not been without limitation, as the tactile feedback is sometimes not noticeable by the user, particularly in miniaturized keyboard assemblies.
Accordingly, it is desirable to manufacture a dome assembly which produces a detectable tactile feedback when electrical contact is made.
A full understanding of the disclosed and claimed concept can be gained from the following Description when read in conjunction with the accompanying drawings in which:
Similar reference numerals refer to similar parts throughout the specification.
An improved handheld electronic device 4 in accordance with the disclosed and claimed concept is indicated generally in
The input apparatus 8 comprises a keypad 20 and a track ball 24. The keypad 20 in the example embodiment depicted herein comprises a plurality of keys 26 that are each actuatable to provide input to the processor apparatus 16. The track ball 24 is rotatable to provide navigational and other input to the processor apparatus 16, and additionally is translatable in a direction inwardly toward the handheld electronic device 4 to provide other input, such as selection inputs. The track ball 24 is freely rotatable on the housing 6 and thus is able to provide navigational inputs in the vertical direction, i.e., the up-down direction, in the horizontal direction, i.e., the left-right direction, as well as combinations thereof. The keys 26 and the track ball 24 serve as input members which are actuatable to provide input to the processor apparatus 16. The example output apparatus 12 comprises a display 32.
As shown in
Examples of other input members not expressly depicted herein would include, for instance, a mouse or track wheel for providing navigational inputs, such as could be reflected by movement of a cursor on the display 32, and other inputs such as selection inputs. Still other example input members would include a touch-sensitive display, a stylus pen for making menu input selections on a touch-sensitive display displaying menu options and/or soft buttons of a graphical user interface (GUI), hard buttons disposed on the housing 6 of the handheld electronic device 4, and so on. Examples of other output devices would include a touch-sensitive display, an audio speaker, and so on.
The processor apparatus 16 comprises a processor 36 and a memory 40. The processor 36 may be, for example and without limitation, a microprocessor (μP) that interfaces with the memory 40. The memory 40 can be any one or more of a variety of types of internal and/or external storage media such as, without limitation, RAM, ROM, EPROM(s), EEPROM(s), FLASH, and the like that provide a storage register, i.e., a machine readable medium, for data storage such as in the fashion of an internal storage area of a computer, and can be volatile memory or nonvolatile memory. The memory 40 has stored therein a number of routines 44 that are executable on the processor 36. As employed herein, the expression “a number of” and variations thereof shall refer broadly to any nonzero quantity, including a quantity of one. One of the routines 44 is a disambiguation routine that is operable to disambiguate ambiguous text input, such as when one of the keys 26 having a plurality of letters assigned thereto is actuated.
Underlying each of the plurality of keys 26 is a deformable dome assembly 50 such as shown in
Referring to
In an application such as a handheld electronic device 4 such as shown in
In the example embodiment shown in
As shown in
The addition of elevating members 58 to the resilient element 52 has been found to produce the desirable attribute of enhancing the tactile feedback to a user of the device compared to the use of a resilient element lacking such elevating members 58 in which the periphery 56 is directly disposed on a mounting surface 60. Such improved tactile feedback can be attributed to a number of characteristics of the present concept. By elevating the periphery 56 of resilient element 52 from the mounting surface 60, a greater travel distance (not numbered) for a depressed key 26, and correspondingly for the apex 54 of the dome shaped resilient element 52 is provided when the resilient element 52 is moved from a non-collapsed position (
The increase in travel distance of the apex 54 allows for the resilient element 52 to become more collapsed than a resilient element 52 with a periphery 56 disposed directly on a mounting surface 60. Also, use of the elevating members 58 allows for utilization of a resilient element 52 requiring a smaller footprint than what would be required of a dome element 52 disposed directly on the mounting surface 60 if a specific key depression distance (generally equivalent to the distance traveled by the apex 54 upon collapsing of dome element 52) is desired.
Reduction of such footprint without decreasing the key depression distance makes the present concept readily adaptable to reduced keypad applications commonly found in handheld electronic devices. Additionally, elevation of the periphery 56 above the mounting surface 60 through the use of elevating members 58 provides improved venting of air from beneath the resilient element 52 upon collapse as well as an improved path for air to return when the resilient element 52 returns to the relaxed position. When the air beneath the dome assembly 50 does not have adequate venting for evacuation or return, such as when the periphery 56 is directly disposed on the mounting surface 60, tactile feedback response is hindered and not as smooth as the case with the elevated periphery 56.
Addition of elevating members 58 to the resilient element 52 has also been found to increase the area of the dome assembly 50 to which a force F may be applied to readily collapse the dome. Increase of such area is desirable by lessoning the potential negative effects of off center actuations or slight misalignments of overlying structures which would tend to not fully collapse the dome and thus not properly register an input.
Use of the elevating members 58 may also provide for reduced constraint of the periphery 56 relative to the underlying mounting surface 60 which in turn reduces the frictional forces acting against dome collapse, thus providing for a more readily collapsible dome. Such reduced constraint may occur by utilizing elevating members 58 that slightly flex outward as the resilient element 52 transitions from the non-collapsed to collapsed position. Such flexure of the elevating members 58 may result in movement of at least a portion of the periphery 56 relative to the mounting surface 60.
While specific embodiments of the disclosed and claimed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed and claimed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof.
