| 摘要 |
<p>A camera has means for preventing charging of a flash capacitor (36) during operation of an automatic focussing device. The automatic focusing device employs a sonic range finder and the flash apparatus comprises a flash tube (40), a capacitor (36), and a D.C. - A.C. - D.C. power converter (38) for charging the capacitor from a battery (34) through a switch (32). A charge regulator comprises a comparator (42) and a switching circuit (46). A disabling circuit (44) prevents the power converter from charging the capacitor when, following actuation of a push-button (29) a switch (S2) indicates that the lens has been moved from and has not returned to a predetermined position, thereby preventing spurious radiation from the converter from affecting the operation of the sonic range finder and also preventing the charging load being imposed on the battery while the automatic focusing takes place. When the capacitor (36) is charged, an enabling circuit (48) permits a trigger circuit (50) to respond to a flash fire signal from the camera. A preview timer (Fig. 4 not shown) may be provided to permit an operator to see and compose the picture after focusing and before he initiates the exposure operation. <IMAGE></p> |
