GB1337551A - Liquid crystal cells and methods for the manufacture thereof - Google Patents

Abstract

1337551 Modulating light ELECTROVAC FABRIKATION ELEKTROTECHNISCHER SPEZIALARTIKEL GmbH 20 Dec 1971 [21 Dec 1970] 59102/71 Heading H4F [Also in Division G5] A liquid, crystal cell comprises a plurality of stacked glass plates 1, 2 sealingly joined at their edges 6, the spacing between the or each two adjacent plates being determined by a single layer of spaced grains 3 therebetween, the mean grain spacing being, e.g. ten times, greater than the mean grain size, and the space between the plates being filled with liquid crystal (e.g. nematic) material 10. Such a plate is produced by covering a first plate with grains of a grain fraction having limits which, with an upper limit #25Á, differ by #6Á, or with an upper limit >25Á, differ by #25% of the upper limit, the grains being applied by sieving, spraying, screen printing or vibration distribution. It is also possible to retain only the large grains by gripping them between the plates and shaking the others out. The grains are covered with the second plate and the process repeated until the desired stack is produced. The stack is heated and subjected to pressure, the plate edges being joined by welding or glass solder. Depending on the relative softening points of the plate and grain materials, the stack is raised to a temperature at which either hard grains penetrate the plate material or the grains are squashed between the plates, Figs. 4 and 5 (not shown) whereby uniform plate spacing results despite the tolerance on grain size. The cell may be curved at the same time, Fig. 11 (not shown). One or more apertures are left at the edge of each cell, Fig. 2 (not shown), for the introduction of liquid crystal material, before hermetic sealing. The grains may be opaque, but preferably are translucent or transparent with the same refractive index as the liquid crystal, to render them invisible. The glass plates 1, 2 and grains 3 may be of the same material. The plates 1, 2 may be provided with electrode layers 11, 12, which may be patterned, Figs. 6-9 (not shown), whereby the capacity of the liquid crystal is controlled, or alternatively a magnetic field may be applied to the cell. A multi-layer cell, Fig. 10 (not shown), may include different liquid crystal materials, or different foreign (coloured) substances in the several liquid crystal layers, e.g. for use as a colour television display.