| 摘要 |
PURPOSE:To reduce the size and weight and stabilize the electric characteristic by coating the outer surface of a metal plate and the inside of through holes where electrode lead wires are to be passed with an electrically insulating film to form a substrate, and mounting a bulb and electrodes on the substrate. CONSTITUTION:Nearly all of the outer surface of a metal plate 21A and through holes made in the thickness direction of the metal plate 21A where electrode lead wires 26 are to be passed are coated with a thin glass film 21B to insulate electrically. A pair of electrodes 25a, 25b are mounted on the substrate 21 in both end sections of a glass bulb 20 via transparent stems 24 with convex surfaces facing upward. Electrode lead wires 26 connected to the electrodes 25a, 25b are passed through the through holes 23 to the outside. Because the outer surface of the substrate 21 and the inside of the through holes 23 are coated with a thin glass film 21B, the pair of electrodes 25a, 25b and the electrode lead wires 26 are electrically insulated from the substrate 21 and short- circuiting of these parts can be surely prevented.
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