Patent Grant
8921720
This disclosure relates generally to key assemblies.
Key assemblies are known in the art. Key assemblies often comprise a keycap that works in combination with a contact-responsive switch. The keycap typically provides a surface configured to interact with an end-user's finger. By ordinarily biasing the keycap away from the contact-responsive switch, the end user can selectively press the keycap towards the contact-responsive switch to momentary close (or open, if desired) the latter. Upon releasing this pressure the keycap then returns to its stand-by position.
Some key assemblies are so-called film-style key assemblies. Such an assembly can comprise a silicone key mat having a raised area (presenting, for example, a relatively short isosceles-trapezoidal cross section) and a corresponding conformal upper layer comprised of a resilient material such as thermoplastic polyurethane (TPU). The key mat typically serves to make physical contact with the contact-responsive switch (or to at least transfer the end-user's finger pressure to that switch) while the resilient material typically serves to bias a corresponding keycap (which often has a flat, planar bottom surface that rests atop the aforementioned raised area) away from the contact-responsive switch.
While satisfactory for many application settings, such a film-style key assembly nevertheless poses certain concerns. For example, the keycap in such an assembly can sometimes be inadvertently peeled away from the raised area when subjected to a pulling force. As another example, such a key assembly can exhibit relatively poor tactile feel owing, at least in part, to having the resilient material conformally track the sides of the raised area of the silicone key mat. In particular, this configuration permits the resilient material to considerably increase the actuation force needed to urge the keycap towards the contact-responsive switch and hence increases the overall rigidity of the key assembly. This resilient material can also laterally transfer actuation forces in a manner that can permit unwanted interaction between, for example, adjacent key assemblies as comprise a part of a keyboard.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure. Certain actions or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.
Generally speaking, pursuant to these various embodiments, a key assembly comprises a keycap having a plinth extending from an underside surface thereof and a contact-responsive switch. A key mat disposed between the keycap and the contact-responsive switch has a recessed area formed therein. This recessed area is sized and configured to receive the plinth.
By one approach this recessed area is sized and configured to conformally receive the plinth. If desired, an adhesive can serve to physically adhere the keycap to the key mat.
By one approach, the key assembly also comprises an elastic layer disposed between the keycap and the contact-responsive switch. If desired, this elastic layer and the aforementioned key mat are integrally coupled to one another. By one approach this elastic layer has at least one opening disposed therethrough. This opening (or these openings) can be disposed at least in part in common with the aforementioned recessed area of the key mat.
So configured, the elastic material serves to aid in biasing the keycap away from the contact-responsive switch while avoiding undue perpendicular rigidity that can contribute to a poor tactile feel. Such an approach also serves to reduce the likelihood that the keycap can be inadvertently peeled away from the key assembly. The result is a key assembly that is both more durable and that has a better feel during use.
These teachings are readily implemented using common and ordinary materials and fabrication methodologies. Accordingly such benefits can be achieved in an economical manner. These teachings are also highly scalable and can serve with a wide variety of keycap sizes, shapes, and form factors.
These and other benefits may become clearer upon making a thorough review and study of the following detailed description. Referring now to the drawings, and in particular to
At step 101 this process 100 provides a contact-responsive switch. Such switches are well known in the art and often (though not always) comprise normally-open switches. Accordingly, and further as these teachings are not necessarily overly sensitive to particular choices in these regards, further elaboration regarding the construction of such switches will not be provided here aside from noting that contact-responsive switches designed for use in a mobile communication device application setting often have a dome size of about 3 to 6 millimeters.
This process 100 accommodates, as will be described below, the use of a key mat. As an optional step 102, this process 100 will also accommodate forming this key mat and an elastic layer as an integral component. By way of illustration and not by way of limitation, and referring momentarily to
As illustrated, this elastic layer 200 can have at least one opening 201 disposed therethrough. By one approach this can comprise providing a plurality of such openings 201. As will become more evident below, this opening 201 can be disposed at least in part in common with a recessed area of the aforementioned key mat. By one approach, and as shown in
Optionally, if desired, this elastic layer 200 can be formed in conjunction with an ink pattern 203. As shown in
As noted above, this elastic layer 200 (formed, for example, of thermoplastic polyurethane) can be integrally formed with a corresponding key mat 400 (formed, for example, of silicone) to yield an integral component. (As used herein, this reference to “integral” will be understood to refer to a combination and joinder that is sufficiently complete so as to consider the combined elements to be as one. Accordingly, two items would not be considered “integral” with respect to one another if they are merely connected to one another by the action of a holding member such as a screw, bolt, clamp, clip, or the like.) One can employ, for example, a co-molding process as known in the art to achieve this result.
Referring now momentarily to
This key mat 400 further includes a raised wall 401 that extends outwardly of the key mat 400 and that forms within its boundaries the aforementioned recessed area. As will be shown below, this recessed area is sized and configured to receive the plinth of a keycap to facilitate physically coupling the keycap to the key mat 400.
So configured, the aforementioned elastic layer 200 comprises a substantially-planar member. In particular, this elastic layer 200 does not arc outwardly in order to conform to an outwardly-disposed bulge in the key mat 400 as typifies many prior art embodiments. Accordingly, although this elastic layer 200 can still serve to bias a keycap away from the opposing side of the key mat 400, such a planar configuration serves to improve the tactile feel of a resultant key assembly.
By one approach, the key mat 400, the elastic layer 200, or both may be comprised of transparent or highly translucent material. Such an approach can serve to support the provision of an internally-illuminated key assembly. Internally-illuminated keyboards and the like comprise a known area of endeavor that requires no further description here.
In any event, and regardless of whether the key mat has been integrally combined with an elastic layer, with reference to
As explained above, the key mat's recessed area is sized and configured to receive a keycap's plinth.
By one approach the key mat's recessed area can be sized and configured to tightly conform to the keycap's plinth 503. In this case, it is possible that the resultant compressive force may suffice to retain the keycap in an installed orientation. Referring again to
In any event, with continued reference to both
When an end user presses on the keycap 600, however, the key mat 400 will be urged towards the contact-responsive switch 502 until the key feature 501 makes operable contact therewith to close (or open, as the case may be) the contact-responsive switch 502. This state persists until the end user releases this pressure. The key mat 400, assisted in considerable part by the elastic layer 200, then returns to its quiescent state of rest and the key feature 501 disengages with the contact-responsive switch 502.
The aforementioned openings 201 in the elastic layer 200 are not so large as to unduly interfere with the elastic layer's 200 significant contribution in the above-described regards. These openings 201 are of sufficient size, however, to both improve the perceptible tactile feel of the key assembly 700 and also to considerably reduce any physical lateral crosstalk between this particular key assembly 700 and any adjacent key assemblies.
Such a key assembly 700 can comprise a part of a larger assembly. As one illustrative example in these regards, and referring now to
Such a keyboard 801 can, in turn, operably couple to a control circuit 802 that itself operably couples to a wireless transceiver 803 of choice. Such a control circuit 802 can comprise a fixed-purpose hard-wired platform or can comprise a partially or wholly programmable platform. Such architectural options are well known and understood in the art and require no further description here. So configured, the keyboard 801 can permit an end user to provide instructions or content to the control circuit 802 as appropriate to control circuit's functionality and capabilities.
Such a key assembly can be readily manufactured using readily-available materials and fabrication techniques. Accordingly, these teachings can be employed to leverage and further extend the use and value of such existing approaches. These teachings are also readily scaled to accommodate a variety of differently-sized contact-responsive switches and key caps and a variety of differently-arranged keyboards. These teachings can be economically practiced and serve to provide a key assembly that is reliable and durable during use.
Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the disclosure, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept.
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| Number | Date | Country | |
|---|---|---|---|
| 20120267227 A1 | Oct 2012 | US |
