GB477384A - A new projection screen - Google Patents

Abstract

477,384. Projection screens. MARTINEZ, A., MARTINEZ, M., and MARTINEZ, A. March 25, 1936, Nos. 8917 and 8918. Convention dates, March 25, 1935 and Feb. 29, 1936. [Class 97 (i)] A screen moved continuously or reciprocated in the plane of the projected image comprises specular surfaces arranged in rows which are transverse to the direction of motion, the surfaces having relatively small radii of curvature in the direction of motion and relatively large radii of curvature in a direction transverse thereto ; all the surfaces in one row are parallel to the projection plane or are inclined thereto at the same angle, and the surfaces in any one row are displaced relatively to the surfaces in adjacent rows or have an inclination different from the inclinations of those in adjacent rows. The curvatures may be derived from a circle, parabola, cycloid, hyperbola, or ellipse, or from combinations thereof. The projected images may be stereoscopic pairs, or may be projected from solid objects. Fig. 6 shows part of the surface of a screen in which the specular surfaces 1a ... 1l are arranged in horizontal rows, the surfaces in each row being laterally displaced relatively to those in the rows above and below them, to form cycles in which the rows 1a and 1l correspond. Each surface distorts a light point into a line f ... i, and the vertical movement of the screen causes the lines to produce light areas F ... I which are contiguous and cover the image field. Fig. 4 shows diagrammatically the positions of the surfaces in four consecutive rows of an alternative construction, in which the surfaces a ... d in the rows are not laterally displaced but are arranged at different inclinations to the projection plane. The surfaces may be formed in rows from sheet-metal, as shown at c, Fig. 5, or may be cast, pressed, &c. in cycles ; the vertices of the surfaces in each row may lie on a circular arc. The surfaces may be carried by chains running over rollers 5, Fig. 10, and the rows may be contiguous or spaced to permit the spectators to see objects &c. behind them or scenery &c. painted on a canvas 17. The canvas 17 may be wound on rollers 18, so that the scenery may be varied, and a multicoloured web 19 wound on rollers 20 and illuminated by lamps 21 may be provided behind the canvas ; the canvas may be omitted, .when the web and lamps are provided. A construction is described in which the screen is rotated in the projection plane, the rows of surfaces being radial. Fig. 12 shows a construction for rear projection, in which the specular surfaces 1 are backed by plane specular surfaces 24 inclined at 45‹, the projected image being viewed in the surfaces 24. Shutters 26 cut off direct vision of the projector lens.