| 摘要 |
1,258,377. Testing lamps. AGFA-GEVAERT A.G. Feb.20, 1970 [Feb.21, 1969], No.8210/70. Heading G1U. [Also in Divisions G2 and G3] Photographic flash apparatus includes a switching device, as shown on transistor 2, which can assume a switched state in accordance with the magnitude of a voltage applied to its input, and indicator means, as shown on lamp 3, for indicating the switched state of the transistor 2, the apparatus being arranged so that, in operation, the lamp 3 provides a visual indication of the flashreadiness of a flash-bulb 11 connected to terminals 12, 13 when they are connected to the transistor input by way of a dropping resistor 10. The apparatus may form part of a photographic camera. The circuit shown also includes means for indicating inadequate lighting conditions and the condition of the power source 1 of the apparatus. To test an inserted flash-bulb 11, when there is adequate light, a photo-resistor 8 is shaded. If the bulb 11 is defective, when switch 4 is closed the indicator lamp 3 will light up. To test the battery, a changeover switch 6, 7 and a testing switch 15 are actuated. The resistances of resistors 5, 9 are of such magnitude that, until the battery voltage falls below a prescribed minimum value, the lamp 3 lights up. If there is inadequate light and no flash-bulb 11 present, the indicator lamp 3 will light up due to the high resistance of the photo-resistor 8. Insertion of a good flash-bulb will cause the lamp 3 to go out. The lamp 3 comes on again when the flash-bulb 11 is ignited and remains on until a new flashbulb has been inserted or the flash-cube rotated. In another embodiment Fig.2 (not shown), a camera has exposure control means including means for indicating flash readiness and for indicating the adequacy of the lighting conditions. A photoresistor (24) and a capacitor (25) control the exposure period. A third embodiment, Fig. 3 (not shown) is similar to that of Fig.1, but includes a capacitor (40) for actuation simultaneously with the synchro-switch. The capacitor causes a time delay in current reaching the lamp (3), an advantage if the battery (1) has a reduced output. |
