| 摘要 |
<p>A diaphragm apparatus has a rotary arm and first to fourth diaphragm blades. The rotary arm rotates about a predetermined rotation shaft. The first diaphragm blade is provided with a first pair of sides which are connected to the rotary arm and which are formed to define a V-shaped apex of an obtuse angle so that the first pair of sides come closer to each other as the distance from the rotation shaft increases. The second diaphragm blade is provided with a second pair of sides which are connected to the rotary arm and which are formed to define a V-shaped apex of an obtuse angle so that the second pair of sides come closer to each other as the distance from the rotation shaft decreases. The third diaphragm blade is provided with a third pair of sides which are connected to the rotary arm and which are formed to define a V-shaped apex of an acute angle so that the third pair of sides come closer to each other as the distance from the rotation shaft increases. The fourth diaphragm blade is provided with a fourth pair of sides which are connected to the rotary arm and which are formed to define a V-shaped apex of an acute angle so that the fourth pair of sides come closer to each other as the distance from the rotation shaft decreases. The area of an aperture defined by the first to fourth pairs of sides surrounding the same varies in accordance with the rotation of the rotary arm.</p> |
