Illumination – Revolving
Reexamination Certificate
2001-04-16
2002-10-22
O'Shea, Sandra (Department: 2875)
Illumination
Revolving
C362S023000, C362S029000, C362S030000, C362S084000, C341S022000, C200S313000, C200S314000
Reexamination Certificate
active
06467924
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to keyboards, including typewriter and computer keyboards.
More specifically, the present invention relates to keyboards having illuminated key members.
Conventional keyboards include a plurality of key members which display symbols, such as alphanumeric keys, on their top surfaces. Moreover, typical modern keyboards for both electric typewriters and computers utilize a make-and-break electrical circuit which is activated by depression of a key member for identifying a particular symbol embedded on the top of the key member.
A problem with prior art keyboards is that it is often difficult to discern the symbol appearing on the top of the key member under poor lighting conditions. This causes the keyboard operator to memorize the key locations or to strain their eyes to operate the keys of the keyboard under low light conditions. This has become a much greater problem in present day society as keyboards have become necessary for everyday use and as keyboard use is not limited primarily to operation by workers in business offices as in the past. As a result of this expansion of keyboard use, more and more operators have less training on keyboards, and correspondingly many keyboard operators utilize a “hunt and peck” style of keyboard operation.
Moreover, the advent of laptop and notebook computers has resulted in the use of keyboards at places where they were not previously operated. Often these places provide limited light making it difficult for keyboard operators to quickly and easily operate the keyboard. For example, it is a common sight on commercial aircraft to see a passenger slowly hunt and peck at their keyboards continuously looking at the key members to verify that they are in fact pressing the correct keys.
Accordingly, it is clear that there is a need for an apparatus that makes keyboard key members more discernable in low light conditions. Backlighting is commonly used in rubber keypads, membrane switches, rigid panels and the like to make them more visible and discernable. These keypad panels typically make use of light emitting crystals (LECs), liquid emitting diodes (LEDs), and/or fiberoptics for this purpose. Most prior backlit keyboards utilize a light source which is typically transmitted via a fiberoptic cable to the key members of a keypad. For example, U.S. Pat. No. 5,034,602 issued to Garcia, Jr. et al. discloses an optically activated keyboard which uses fiberoptic cables to transmit light to translucent key members. The light is transmitted through the translucent key members where it is emitted from the top of the key cap. Similarly, U.S. Pat. No. 3,886,544 issued to Narodny and U.S. Pat. No. 5,097,396 issued to Myers disclose keyboards which use backlighting. Each key member in connection to a fiberoptic cable which transmits light to a respective key member which thereafter transmits light from the top of the key cap. Additional keyboard and keypad techniques include the LED and LEC backlighting commonly utilized for alarm activator and deactivator keypads wherein each key includes a separate LED or LEC structure embedded in or behind the key member.
Unfortunately, keyboard and keypad backlighting devices which utilize LED, LEC or fiberoptics are relatively expensive to construct. In addition, it is extremely difficult, if not impossible, to route fiberoptics to the keyboard keys of today's computer systems. For example, it would be particularly difficult to route fiberoptic cables and provide a light source to the key members of today's notebook computers and palm-sized computer systems.
In addition, the light sources for use with prior art backlit keyboards require substantial power and in some cases, a fan for cooling which draws additional power. These constructions are prohibitive for portable computers such as laptop and notebook computers which draw on the power of a rechargeable battery and where power is at a premium.
Accordingly, it would be highly advantageous to provide a keyboard having illuminated key members suitable for use with today's computer systems including portable computers.
It would also be highly advantageous to provide a keyboard having illuminated keys which does not require routing of fiberoptic cables to each key member.
In addition, it would be highly advantageous to provide a keyboard having illuminated key members which is light weight, simple and inexpensive to manufacture, and requires low power consumption.
SUMMARY OF THE INVENTION
Briefly, in accordance with the invention, I provide an improved keyboard having illuminated key members. The improved keyboard includes a plurality of key members and, preferably, a light channeling membrane. Both the light channeling member and key members are constructed of a substantially translucent material capable of channeling light rays. In addition, the keyboard of the present invention includes a light source optically connected to the light channeling membrane. In operation, the light source produces light rays which are received by the light channeling membrane which underlies the plurality of key members. The light rays are channeled through the light channeling membrane to the key members which receive the light rays at their lower extremities and channel the light rays upwardly to their top surface. Light is then emitted from the top of the key member to either provide illumination around an opaque construction of a symbol displayed on the top surface of the key member, or in the alternative, to emit light rays in the shape of the symbol itself.
In a preferred embodiment, the light channeling membrane and plurality of key members are manufactured of an acrylic plastic for optical clarity, though other materials may be used depending on weight and manufacturing limitations as would be understood by those skilled in the art. For this embodiment, the light channeling membrane includes a plurality of bores, with each bore being constructed for receipt of the key shaft of a corresponding key member. Meanwhile, each key member also includes a key cap having a symbol displayed thereon. Each key member shaft is constructed to extend downwardly and telescopically into a corresponding bore of the light channeling membrane. Light is channeled through the translucent material of the light channeling membrane until it is emitted from cylindrical sidewalls into the membrane's bores. Light emitted from the bores' interior sidewalls is received onto the exterior of the shafts of the key members and channeled upwardly through the translucent material of the shaft, to the key caps which are also constructed of a translucent material. The key cap includes an upper surface having an alphanumeric symbol displayed thereon which is illuminated by light passing through the shaft of the key member to provide the desired illuminated alphanumeric symbol. The symbol can be constructed as light emitting or as opaque with the remainder of the top surface being conversely opaque or light emitting, depending on whether the desired symbol is in either a negative or a positive representation thereof.
In a preferred embodiment, the light source is constructed of a substantially planar sheet underlying the light channeling membrane of the keyboard. A preferred construction for the illuminating sheet of the light source is described in U.S. Pat. No. 5,045,755 issued to Appelberg and assigned to E-Lite Technologies, Inc. which is incorporated herein by reference. The illuminating sheet is a split electrode or parallel plate lamp consisting of a main body sandwiched between first and second conductive layers. Application of an alternating current to the planar sheet provides a luminescent sheet which can be adhesively attached to the bottom of the keyboard light channeling membrane. Moreover, the illuminating sheet is sufficiently thin as to not require significant modification to existing computer keyboards designs.
An additional preferred construction of the luminescent sheet can be obtained from MKS, Inc. located
Drummond & Duckworth
Hobden David V.
O'Shea Sandra
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