Abstract: A spring washer improves resistance to loosening of fasteners tightened thereon. The spring washer is stronger than prior art devices. On the upper and lower surfaces of the spring washer, approximately 1/5-1/4 of the width inward from the outer perimeter is formed without V-shaped grooves. The remaining flat portions are formed with V-shaped grooves in various patterns. These V-shaped grooves increase the coefficient of friction and resist loosening of the spring washer.

Abstract: An aperture assembly is described for use in a motion picture camera, parularly a camera using film cartridges and requiring an aperture assembly with a very thin profile. The aperture assembly includes a thin metal base plate to provide strength for the assembly and for alignment of aperture components thereon. The aperture components include a thin molded aperture piece and a pair of thin molded cartridge alignment shoulders, all mounted on one side of the base plate. The base plate and the aperture piece both have aligned exposure windows through which the film is exposed and aligned slits for receiving a shuttle tooth for advancing the film. Each of the cartridge alignment shoulders has an internal groove communicating with a slit in the base plate for receiving a shuttle foot. A shuttle and a side tension member for use with the aperture assembly are also described.