| 摘要 |
PURPOSE:To decrease the shadow of a discharge-path restricting body by making the side end surface of the said restricting body to be constituted of slant surfaces slanting away from the inner wall of a bulb, and a bulb touching part having the said slant surfaces on both sides. CONSTITUTION:A discharge-path restricting body 4 consists of a main part 41 which is a flat surface, a side end surface 44 consisting of a bulb touching part 42 which is the top of the V-shaped part 44 and touches the inner surface of a bulb 1, and slant surfaces 43a and 43b which slant away from the inner wall of the bulb 1, and a side part 45 which slants parallel to the slant surface 43a and connects one end of the main part 41 to one end of the slant surface 43b. Here, the discharge-path restricting body 4 touches the bulb 1 at the linear contact 42. |
