PURPOSE: To provide a safe and satisfactory illuminating source for a liquid crystal display by sealing a self-light emitting paint of tritium with a transparent resin.
CONSTITUTION: A self-light emitting paint 8 of tritium, to the upper side of which a white light storage paint 13 is applied, is enclosed a sealing material of triethylene fluori-chloride which is transparent while containing no hydrogen. A light storage paint 10 is applied to the upper side of an element 9. Those parts including a liner 11 of aluminum or titanium are sealed with a similar transparent resin 12 containing no hydrogen and are arranged below a liquid crystal cell. When the liquid crystal cell is illuminated, the self-light emitting paint of tritium having a long life, which has its safety ensured by the seal, becomes a satisfactory illuminating source to provide a watch, in which the display can be made to a satisfactory extent even at night, can be produced.