Assertion: shutter's blade | /r/CapableOf | cover the lens
Facets:
Source sentences:
text: A simple and popular design was known as the 'Rebound', a blade was held in front of the lens by a catch against the force of an elastic band, when the catch is released the elastic band pulls the blade up and is dislodged allowing the blade to fall back and cover the lens.
text: J. Swift patented an arrangement where the lower blade was pulled down by a spring, the upper blade was pulled up by a spring that dislodged itself (similar to a rubber-band drop shutter) allowing the upper blade to fall and cover the lens.