A sign module for forming a display of a set of alphanumeric characters one at a time in a viewing window, said module comprising:
- a set of display tapes, each tape being imprinted on both front and back surfaces at discrete surface segments along its length with a discrete character segment of one character, all character segments on the front surface of a given tape corresponding to the same relative part of the different characters, and all character segments on the back surface of a given tape corresponding to the same relative part of the different characters, the number of display tapes in the set being equal to one-half the number of character segments presented at a time in said viewing window, a driving roller and a slave roller for each tape connected with opposite ends of the respective tape and supporting the respective tape with one surface segment of each surface being displayed in said window at a portion of the window which is in positional correspondence with the character segment represented, the surface segments on both surfaces of each tape being progressively longer from one end of the tape to the other, the character segments being nonuniformly spaced along the length of the tape whereby equal angular displacements of the driving roller causes successive character segments to be aligned with the respective window portions, the set of surface segments being displayed together in said window all bearing different character segments of the same character whereby an entire character is displayed, the diameter of each roller being approximately equal to the length of one surface segment along the length of the tape, the driving and slave rollers for all tapes in the set being disposed with their axes in the same plane, means for displacing the driving rollers simultaneously through equal angles for displacing said tapes in unison along their length to successively present the character segments in registry with the respective window portions whereby the characters of said set are successively displayed, each of the driving rollers and each of the slave rollers being mounted upon a shaft, said means for displacing including a driving roller gear connected with the shaft of each driving roller and a slave roller gear connected with the shaft of each slave roller, all gears being of the same size, the driving roller gear associated with any tape being in mesh with the slave roller gear associated with the same tape and only one of the gears associated with each tape being in mesh with one of the gears associated with another tape, each of said slave rollers being provided with a spring drivingly connected between the roller and its respective shaft whereby the tape on each pair of driving and slave rollers is maintained in tension and differential rotation between a slave roller and its shaft is taken up by the respective spring.