| 摘要 |
<p>Methods and apparatus for supplying and controlling simmer current to a flashlamp (28). A direct current-to-direct current converter including a transformer (12), full-wave bridge rectifier (24), and first and second switching means (20) and (22) produces an output which is always higher than the maximum required by the flashlamp (28) at its lowest simmer current. The converter (12, 20, 22, 24) is coupled to flashlamp (28) through an inductor (26). The current I(s) through a pair of inductors (26), (30) is sensed by a lamp current sensing circuit (34) which turns the converter on or off, respectively, when a preselected minimum or maximum value is reached. The converter transformer (12) is maintained in its operating range by the switching of two devices such as power FET's (20, 22) so that one or the other of the two halves of the primary winding (14) is used alternately. The initial ionization of flashlamp (28) is provided by simmer trigger circuit (38). A transformer primary current sensing circuit (40) controls the toggling action which alternates the operation of switching means (20 and 22). The advantages of this method for supplying and controlling flashlamp simmer current include fast current response, extended flashlamp life, simplicity of design, high efficiency, and the avoidance of saturation and synchronization problems.</p> |
