| 摘要 |
PURPOSE:To prevenr variations of dumping characteristics, and to control lens drive invariably stably by fitting bimetals to a lens holding frame and then compensating temperature fluctuations of magnetic fluids between the bimetals and yokes automatically by variation in gap interval. CONSTITUTION:At the opposing sides of an objective holding frame 5 to the 1st and 2nd yoks 2a and 2b, bimetals 11a and 11b are stuck and magnetic fluids 8a and 8b fill gaps between the bimetals and yokes. Consequently, as the magnetic flux temperature rises, the bimetal temperature also rises and the bimetals curve and become convex to reduce the gap interval. Then, a decrease in dumping operation based upon a decrease in viscosity with the temperature rise is compensated to obtain excellent dumping characteristics automatically. When the temperature drops, they curve reversely to increase the gap, thus performing compensation similarly. Therefore, invariably stable control over lens drive is exercised. |
