| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultraviolet irradiator which is less in power consumption.SOLUTION: An output S1 of an illuminance sensor provided on the ultraviolet irradiator abides, as shown in Fig.6 (A), in a variable or invariable state depending on the flow or stoppage state of treated water. The illuminance of the treated water fluctuates as shown in Fig.6 (B) in this case. In a case where D≥α holds, namely where the treated water abides in a flow state, a drive signal S2 of an ultraviolet lamp is set at "1" (ON state). In a case where D<α holds, namely where the treated water abides in a stoppage state, on the other hand, the drive signal S2 is inverted. As a result, the drive signal S2 shown in Fig.6 (C) is obtained. As shown in Fig.6 (C'), namely a magnified representation of Fig.6 (C), in a case where the treated water abides in the flow state, the drive signal S2 is set at "1" (ON state), and the ON state of the ultraviolet lamp is perpetuated, whereas, in a case where the treated water abides in the stoppage state, on the other hand, the drive signal S2 abides in a duty ratio=50% intermittent state, and the ultraviolet lamp is driven intermittently. At this time, the temperature of the treated water varies as shown in Fig.6 (D) due to the heat evolution of the ultraviolet lamp. |
