| 摘要 |
<p>A flash tube 10 has a photoelectric time control 17, 18 and a supplementary time control 35 for switching off the tube after a predetermined time if the photoelectric control has not already done so. This is to ensure that the supply capacitor 13 does not become completely discharged. The recharging of the capacitor 13 which is only partially discharged, makes more efficient use of the current storage supply 11, reducing the need for frequent recharging of the current storage supply. Fig. 2 (not shown) shows an alternative form of supplementary control 35. <IMAGE></p> |
