Illuminated pen

Claim 1

A SELECTIVELY SELF-ILLUMINATING WRITING INSTRUMENT COMPRISING A BARREL HAVING THREADED ENDS, A TRANSPARENT TIP THREADED ON ONE END OF THE BARREL, A CAP DETACHABLY THREADED ON THE OTHER END OF THE BARREL AND HAVING A CARTRIDGE RETAINING CAM THEREON, A CENTRAL FLANGE INTERIORLY OF THE BARREL ADJACENT TO THE TRANSPARENT TIP, A REFLECTING CHAMBER AND A CARTRIDGE CHAMBER IN SAID TRANSPARENT TIP, A BORE IN SAID TRANSPARENT TIP AXIALLY ALIGNED WITH SAID CARTRIDGE CHAMBER AND EXTENDING THEREFROM TO THE OUTER PERIPHERY OF THE TRANSPARENT TIP, A WRITING CARTRIDGE FOR PROJECTION FROM THE TRANSPARENT TIP RELEASABLY HELD IN THE CARTRIDGE CHAMBER AND EXTENDING INTO SAID BORE, A SWITCH MEANS SLIDABLY ATTACHED ON THE BARREL, AND AN ELECTRIC ILLUMINATING MEANS WITHIN THE BARREL FOR ILLUMINATING THE REFLECTING CHAMBER IN THE TRANSPARENT TIP AND CONTROLLED BY THE SWITCH MEANS, SAID SWITCH MEANS BEING MANUALLY OPERABLE FROM THE OUTSIDE OF SAID BARREL.