LIGHTGUIDE SUBASSEMBLY FOR RECEIVING A TRACKBALL NAVIGATIONAL TOOL MOUNTABLE WITHIN A HANDHELD MOBILE DEVICE

1 . A user input subassembly configured to be installed in a handheld wireless communication device and to include a trackball navigational tool and a field of input keys in a fully assembled configuration, said user input subassembly comprising:

a lightguide panel constructed of light diffusing material and having a back face configured to be located adjacent a concentrate light source and a front face configured to be located adjacent a backside of a field of input keys; and

a trackball navigational tool receiver formed at least partially in said lightguide panel, said trackball navigational tool receiver configured to receive and fix a trackball navigational tool relative to said lightguide panel when installed therein.

2 . The subassembly as recited in claim 1 , wherein said lightguide panel has a thickness spanning between said front and back faces whereby concentrate light entering said lightguide panel across a light-entrance surface area of said back face is diffused and emitted from said lightguide panel across a light-exit surface area of said front face as diffused light and wherein said light-entrance surface area is less than the light-exit surface area.

3 . The subassembly as recited in claim 2 , further comprising a plurality of concentrate light sources, each located adjacent said back face of said lightguide panel, said plurality of concentrate light sources being of sufficient number and respectively located relative said lightguide panel that said light-exit surface area constitutes a majority of said front face of said lightguide panel.

4 . The subassembly as recited in claim 3 , wherein each of said plurality of concentrate light sources is a light emitting diode (LED).

5 . The subassembly as recited in claim 1 , wherein said trackball navigational tool receiver further comprises at least one releasing securement feature formed at a surface of said lightguide panel, said at least one releasing securement feature configured to engage a mating securement feature stationarily located on an installable trackball navigational tool.

6 . The subassembly as recited in claim 5 , further comprising a trackball navigational tool comprising a securement feature matingly engaged with said releasing securement feature formed at the surface of said lightguide panel.

7 . The subassembly as recited in claim 6 , wherein said securement feature on said trackball navigational tool comprises a barbed insert snap-engaged in said securement feature formed at the surface of said lightguide panel thereby establishing a releasable interference connection between said trackball navigational tool and said lightguide panel.

8 . The subassembly as recited in claim 6 , wherein said securement feature on said trackball navigational tool comprises a ramped insert press-fit into said securement feature formed at the surface of said lightguide panel thereby establishing a releasable friction connection between said trackball navigational tool and said lightguide panel.

9 . The subassembly as recited in claim 6 , further comprises a lock ring at least partially surrounding the trackball navigational tool.

10 . The subassembly as recited in claim 9 , wherein said lock ring comprises a barbed insert snap-engaged in said securement feature formed at the surface of said lightguide panel thereby establishing a releasable interference connection between said trackball navigational tool and said lightguide panel.

11 . The subassembly as recited in claim 9 , wherein said lock ring comprises a ramped insert press-fit into said securement feature formed at the surface of said lightguide panel thereby establishing a releasable friction connection between said trackball navigational tool and said lightguide panel.

12 . The subassembly as recited in claim 9 , further comprising a keypad mountable on the front surface of said lightguide panel, wherein said keypad includes the keyfield.

13 . The subassembly as recited in claim 12 , further comprising a dome sheet mountable on the back face of said lightguide panel.

14 . The subassembly as recited in claim 13 , wherein said dome sheet has a plurality of apertures for transmitting said concentrate light source to the lightguide panel.

15 . The subassembly as recited in claim 14 , wherein said concentrate light source is mounted on a PCB board.

16 . A handheld wireless communication device configured to send and receive text messages, said device comprising:

a hand cradleable body configured to be held in a text entry orientation by an operator of said device during text entry, said body having a front face at which a display is located and upon which information is displayed to the operator of the device in the text entry orientation;

a microprocessor configured to run software programs on the device and to receive operator commands from user inputs located on the device;

a lightguide panel constructed of light diffusing material and having a back face configured to be located adjacent a concentrate light source and a front face configured to be located adjacent a backside of a field of input keys; and

a trackball navigational tool receiver formed at least partially in said lightguide panel, said trackball navigational tool receiver configured to receive and fix a trackball navigational tool relative to said lightguide panel when installed therein.

17 . The handheld wireless communication device of claim 16 , wherein said trackball navigational tool receiver further comprises at least one releasing securement feature formed at a surface of said lightguide panel, said at lease one releasing securement feature configured to engage a mating securement feature stationarily located on an installable trackball navigational tool.

18 . The handheld wireless communication device of claim 17 , further comprising a trackball navigational tool comprising a securement feature matingly engaged with said releasing securement feature formed at the surface of said lightguide panel.

19 . The handheld wireless communication device of claim 16 , wherein said key field comprises a plurality of keys of which a portion are alphanumeric input keys, said alphanumeric input keys comprising a plurality of alphabetic keys having letters associated therewith that are arranged in one of a QWERTY, QWERTZ, AZERTY, and Dvorak arrangement for facilitating text entry.

20 . The handheld wireless communication device of claim 19 , wherein said letters are associated with said alphabetic keys, one letter per key.

21 . A method for constructing a user input subassembly for a handheld wireless communication device, said method comprising:

forming a lightguide panel from light diffusing material;

locating a concentrate light source adjacent to a backside of the light guide panel;

locating a field of input keys adjacent to a front side of the lightguide panel;

sliding a trackball navigational tool into a trackball navigational tool receiver formed at least partially in the lightguide panel;

fixably engaging said trackball navigational tool to said lightguide panel.