Device for viewing indicia

Claim 1

In a device for viewing a plurality of indicia, one pair of indicia, rotary, light-permeable, carrier means having an axis of rotation and carrying said pair of indicia angularly displaced one with respect to the other by 180* about said axis and axially displaced one with respect to the other along said axis by a distance at least as great as that occupied along said axis by each of said indicia, frame means defining an opening through which the indicia are viewed from one side of said frame means and with which one Of said indicia is aligned when said carrier means is in a given angular position, said carrier means extending along said frame means at an opposite side thereof so that that one of said indicia which is aligned with said opening can be illuminated with light passing through said carrier means toward said opening of said frame means, and said distance of axial displacement of said indicia preventing simultaneous viewing of said indicia so that only that one of said indicia which is aligned with said opening of said frame means can be viewed at one time, operating means coacting with said carrier means for rotating the latter through 180* while axially displacing said carrier means through an increment equal to the axial distance between the pair of indicia and in a direction which will situate the other of said indicia in the position occupied by said one of said indicia when said carrier means is in said given angular position thereof, so that through said operating means one or the other of said indicia will become aligned with said frame means to be viewed therethrough, an additional pair of indicia having with respect to each other the same angular and axial relationship as said one pair of indicia, while said additional pair of indicia alternate with said one pair about said axis with said additional pair of indicia being axially displaced with respect to said one pair by a fraction of the axial distance between said one pair of indicia, so that said additional pair of indicia are in axial overlapping relationship with respect to said one pair of indicia, said operating means coacting with said carrier means for rotating and axially displacing the latter through an angle and linear distance required to place one of said additional pair of indicia in alignment with said opening of said frame means while displacing one of said first-named pair of indicia out of alignment with said opening of said frame means, so that irrespective of which one of all four indicia is aligned with said opening of said frame means there is situated at the side of said carrier means directed away from said frame means another one of said indicia which is axially displaced with respect to the one of the indicia aligned with the opening of the frame means by a distance equal to that occupied by each of the indicia along said axis of said carrier means, and at the same time all four indicia occupy along said carrier means a total axial distance less than the total axial distance of all four indicia added together, and illuminating means coacting with said carrier means for directing light through said carrier means toward said opening to that one of all of said indicia which is in alignment with said opening of said frame means, whereby only the latter one of all of said indicia will be visible at one time.