US Patent 7837580 Lighted nock for archery arrow

An archery arrow carries a light transmitting nock plus a light assembly, which comprises a light source positioned so that the light source is visible through the nock, a switch having normally open electrical contacts, and closable upon momentary contact with a magnetic field, and circuitry interconnecting a battery, the switch, and the light source for permitting illumination of the light source when the magnetic field is sensed. By this invention, the light assembly may be free of a housing and occupies a first bore of the nock and a second bore of the arrow shaft rearward end. A unique system for retaining a battery and protecting against high G force, plus a focused beam LED are other optional, advantageous features.