| 摘要 |
An array of picture elements is disclosed for providing a display having selectivitely light or dark areas. The array includes light valves each comprising a pair of light transmissive elements having facing phase gratings, preferably sinusoidal, of like periodicity and parallel grating lines. The pair of elements are selectively positioned in two positions. In the first position, (the relatively dark transmissive position) the maxima and minima of one of the light transmissive elements are respectively coincident with the maxima and minima of the other light transmissive element. In the second position, (the relatively dark transmissive position) the maxima and minima of one of the light transmissive elements are respectively coincident with the minima and maxima of the other light transmissive element. Preferably the gratings comprise two sets of gratings having lines at right angles to each other, and at 45 DEG to the direction of motion which is used to position the two light transmissive elements from one selected position to the other. They alternatively may comprise three sets of lines at 60 DEG . The two selected positions may be defined by stops. Alternatively, the two positions may be defined by grating facing, complementary complex wave forms. One of the grating lines of one pair of light transmissive elements may be embossed from the other element of the same pair. The individual picture elements are defined by the intersections between rows and columns of the light transmissive elements. The rows employ piezoelectric elements, preferably using PVF2, to lock in place all the picture elements of the rows of the array except, when desired, a selected row, which is free to move, in order to change relative positions of the elements. The columns employ bimorphs, also preferably using PVF2.
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