| 摘要 |
PURPOSE:To obtain a lightweight and simple diaphragm device which eliminates the need for driving and transmission mechanisms by using a piezoelectric element as a light shielding member. CONSTITUTION:The diaphragm device of a camera is provided with a light shielding member 17 having a bimorph construction. The member 17 made of a piezoelectric material deforms like an arrow when an electric field is impressed thereon. The light past an aperture 19 is detected by a photodetector 20, from which a signal is outputted and the signal is processed in an arithmetic and control circuit 21. Said circuit feeds a control signal back to a voltage-variable DC power source 16. If the circuit 21 is so constituted as to output the control signal by which a correct exposure is obtd., the correct exposure is obtd. by controlling the deformation rate of the member 17 according to the signal from the element 20. The member 17 is made into a two-layered structure and four sheets each of said member are fixed in each layer. |
