The deformographic storage display tube

Employing a novel electrostatic configuration, the Deformographic Storage Display Tube (DSDT) incorporates the fast point-by-point light-valve capability of the Eidorphor® technique and the two-sealed-chamber construction of the Electrostatic Storage Display Tube, an earlier IBM development. In the DSDT, a thin mica diaphragm stores the charges written by the electron gun, while the resultant electrostatic field deforms a transparent dielectric elastomer film cast on its other surface (in the second chamber). The optical phase-image thus created is converted by a separate light-source and schlieren optics into a large-screen projected image, which has high contrast, and brightness. The DSDT technique permits selective erasure and update, or erasure by flood-beam. Variable persistence provides image-storage from 20 hrs. or more down to an erase-time of 15 ms. The latter, in conjunction with 15 ms develop-time, is equivalent to TV frame-speed. Spot-size of 2.5 mils has been measured, with the expected limit around 1.5 mils. Sensitivity of <10^-7coulombs/cm²for writing permits recording at TV scan-speed.