| 摘要 |
PURPOSE:To make a right brightness signal coincide with a left brightness signal with good accuracy and without impairing the stability of the control of a diaphragm by a method wherein the target brightness set by one out of right and left control means is corrected according to the difference between brightness signals obtained from a pair of right and left image-sensing elements. CONSTITUTION:A correction circuit 12 operates a correction amount by means of proportional integration in such a way that the average brightness, of an image-sensing element 2R on the right side, which is obtained by an average circuit 8R coincides with the average brightness on the left side while the average brightness, of an image- sensing element 2L on the left side, which is obtained by an average circuit 8L is used as a reference. Then, when, e.g. the average brightness on the right side is slightly log as compared with the average brightness on the left side, the output of the circuit 12 is raised gradually by the action of the integration operation of an operational amplifier A, and the target brightness Vr of a comparator 9R is raised gradually so as to be correspondent. As a result, the opening area of a diaphragm 5R is expanded by the action of a drive circuit 10R and a drive coil 11R. As a result, the average brightness of the element 2R on the right side is raised, and coincides with the average brightness of the element 2L on the left side. |
