US Patent 7991276 Optical image stabilizer and optical apparatus

The optical image stabilizer shifts an image stabilizing element with respect to an optical axis of an optical system to reduce image shake. The stabilizer includes a lock ring which is rotatable to a lock position to limit shift of the image stabilizing element and to a lock-releasing position to allow the shift of the image stabilizing element, an actuator which rotates the lock ring to the lock position and the lock-releasing position, and a biasing mechanism which mechanically biases the lock ring rotated to the lock position toward the lock position and biases the lock ring rotated to the lock-releasing position toward the lock-releasing position.