Patent attributes
A controllable aperture stop includes a light pass portion, a fixed portion, a driving part and rollable elements. The light pass portion includes movable blades together surrounding a light pass aperture. The fixed portion has shaft structures corresponding to the movable blades. The driving part includes a rotatable element, a magnet and a coil. The rotatable element is for driving the movable blades to rotate relative to the shaft structures to adjust the size of the light pass aperture. The magnet is disposed on the rotatable element. The coil corresponds to the magnet. The magnet and the coil are to drive the rotatable element to rotate around the light pass aperture. The rollable elements are disposed between the fixed portion and the rotatable element and arranged around the light pass aperture, so the rotatable element is rotatable relative to the fixed portion.