| 摘要 |
PURPOSE:To improve the upper-lower ratio of a coating amount up to the ratio of the same level such as conventional butyl acetate suspension with a high drying velocity so as to obtain a uniform coating film, by increasing the coating amount of phosphor per unit area at the upper section of the inner surface of a glass pipe and decreasing the coating amount of phosphor per unit area at the lower section. CONSTITUTION:The inner surface of a glass pipe 1 is washed with deionized water from a washing nozzle 4 which is placed above the glass pipe 1 whose upper section is held by a chuck 3 mounted on a conveyer 2. When only the deionized water adhering to the section at about 20 cm away from the top end of the inner surface of the glass pipe 1 is dried, while the deionized water adhering to another section is not dried yet, a water- soluble phosphor suspension is made to flow down from a coating nozzle 6 so that said water-soluble phosphor suspension is spread on the whole inner surface of the glass pipe 1. When the lower section of the glass pipe in not dried state is coated with said water-soluble phosphor suspension, said phosphor suspension which is flowing down is diluted with this pure water, because of the deionized water adhering to the inner wall of the undried section of the glass pipe 1, as a result the coated amount of said phosphor per unit area is decreased. |
