Importance

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Abstract

The character disc of the photocomposing machine has a 'sandwich' construction in which the characters are located close to one another on a piece of film which is 'sandwiched' between two glass plates. The thickness of this construction is such that the mask would have to be located very precisely in order to select only one character. The mask device consists of a pair of shields, a front shield located between the flash lamp and the spinning disc character matrix, and a rear shield between the matrix and the character magnification lens system. Preferably, the shields are close to the matrix and are fastened together. Each shield has an aperture. The aperture in the front shield preferably is larger than that in the rear shield so that the rear shield blocks rays missed by the front shield. The use of the two shields greatly reduces the precision required in the location of the mask over that required if only one shield were used.

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First Claim