GB544388A - Improvements in or relating to light valves - Google Patents

Abstract

544,388. Light valves. ELECTRICAL RE-. SEARCH PRODUCTS, Inc. April 3, 1941 No. 4470. Convention date, April 16, 1940. [Class 40 (iii)] ] Relates to light valves for recording sound on film and comprising apertured pole-pieces 2, 4, Fig. 1, for example as described in Specification 479,083, and consists mainly in the provision of an aperture mounting plate 7, Fig. 3, or 21, Fig. 5, projecting into the aperture of one of the polepieces and carrying a lens 9 or lenses 27 or a slit plate 12 or 29 or both slit plate and lens or lenses. Each pole-piece may be a single. whole or may be built up of separate pieces The polepiece 2 is mounted on or integral with a base piece 1 on which the ribbon clamps 3 are also mounted; and the pole-piece 4 is mounted on a spacing member 5. The pole-pieces and ribbons form a single valve, Fig. 3, or two valves 19, 20, Figs. 5 and 6. The two. valves in these figures are not in line, and two refracting plates 24, 25 are provided in the mounting plate 21 to bring the light passing through the valves in axial alignment with the aperture in the mounting plate. The mounting plate is secured to the base piece 1 by bolts 8, Fig. 3, or 22, Fig. 5, and shims 28 may be provided to adjust the position of the plate. Similarly, the slit plate 12 or 29 in a support 10 or 30 is fastened by bolts to the mounting plate, and shims 13 or 32 are provided to adjust the position of the slit plate. In the double valve, Figs. 5 and 6, opaque partitions or screens are provided between the two paths of light to prevent leakage from one to the other. To prevent disturbance by stray light, the aperture of the mounting plate may be grooved and covered with black paint, ,and the pole-piece 2 may be enclosed in masking plates. The slit plate may be of glass with a coating of aluminium in which a fine slit is inscribed.