GB1095843A - Device for electronic control of shutter speed of photographic cameras - Google Patents

Abstract

1,095,843. Photographic cameras. PENTACON DRESDEN KAMERA-und KINOWERKE VEB. Jan. 27, 1965, No. 3590/65. Heading G2A. A photographic camera shutter includes a time control circuit having a relay for effecting opening and closing of the shutter. A photo-resistor 2 and capacitor 3 are connected to a transistor, the collector of which is connected to galvanometer 6. The collector of a second transistor 11 is connected to the winding of an electromagnet 15. Armature 16 of the electromagnet pivots clockwise about 17 against the action of a spring 18. Two catches 20, 24 effect the drive of shutter blades (not shown). In operation, the switch 9 is closed such that galvanometer 6 indicates on a scale the exposure time. Switch 28 is then closed such that transistor 11 conducts to energize electromagnet 15 and transistor 1 does not conduct. Armature 16 pivots to release catch 20 which effects or permits opening of the shutter blades. Catch 20 releases a bolt 22 which in turn releases catch 24 which is then prevented from moving by contacts with armature 16. After a delay, during which capacitor 3 becomes charged and as a result transistor 1 conducts and transistor 11 becomes non-conductive, the winding of electromagnetic 15 is de-energized. The catch 24 is then able with spring 18 to rotate armature 16 counter clockwise and so close the shutter blades. The shutter release may be delayed e. g. for flash exposures by a capacitor 12 discharged through a resistor 13. For selfportraits, a capacitor 14 is connected in parallel with the capacitor 12, to increase the delay. A capacitor 5 is connected in parallel with capacitor 3 through a variable resistor 4 to provide for under or over exposure.