Patent ID: 8303128

Claim:
A lighting device comprising: a plurality of discharge tubes, each of the discharge tubes including: a glass tube having a primary-seal-side end portion and a secondary-seal-side end portion, the primary-seal-side end portion forming one of two end portions of the glass tube, the secondary-seal-side end portion forming the other of the two end portions; a pair of ferrules attached to the primary-seal-side end portion and the secondary-seal-side end portion, respectively; and an identifier located either on a ferrule or on a nonluminous portion of the glass tube not covered with a ferrule, the identifier indicating at least one of the primary-seal-side end portion and the secondary-seal-side end portion to enable discrimination between the primary-seal-side end portion and the secondary-seal-side end portion; and a chassis capable of containing the discharge tubes arranged parallel in an array.