| 摘要 |
The microfilm cassette consists of a housing having two spaced parallel spindles for winding the film. Between the two spindles is a projection window. The housing, spindles and window are arranged so that the cassette is not guided. The housing, spindles and window are essentially symmetric around three orthogonal planes. The film window being in one of the planes. The spindles are situated on the axes of two closed envelopes connected by a frame which forms the window. The mount has two spaced walls forming slits between each envelope and the window. When the film is wound from one spindle to the other, only the exposed part of the film is displayed in the window. The housing is formed from two identical shells fixed to each other after the film is placed in the cassette. |
