GB581088A - Improvements in and relating to illuminating and viewing apparatus for objects such as photographic transparencies and prints - Google Patents

Abstract

581,088. Apparatus for viewing transparencies and prints. PHILIPS LAMPS, Ltd., and WEST, S. W. June 13, 1944, No. 11318. [Classes 97 (i) and 98 (ii)] Relates to apparatus of the kind described in Specification 387,767. wherein a housing is provided with a diffusing screen against which the transparency &c. is placed, and encloses (1) a lamp which is mounted near one edge of the screen and serves with the aid of a curved reflector to illuminate the screen uniformly, and (2) a movable lamp-masking shutter, e.g. of semi-cylindrical form coaxial with the lamp, for varying the ,intensity of illumination of the screen. The invention consists in providing in the wall of the housing an aperture close to the lamp, and so situated in relation to the masking shutter that the aperture is directly illuminated when the screen is fully masked, and is obscured when the screen is fully illuminated. The aperture affords strong illumination for inspecting dense local portions of the transparency, e.g. an X-ray film. It may be provided with a hinged cover with a reflecting inner surface, so that when the cover is partially open, light from the aperture is reflected to the front surface of the screen and renders possible the viewing of an opaque print laid against the screen. In the form shown, the housing 1 has a curved, internally-reflecting rear wall whereby light from one or more lamps 3, e.g. of the elongated electric discharge type, in a ventilated ,casing 9 is caused to illuminate uniformly a diffusing screen 2 on the front of the housing. Half encircling the lamp is a shutter 5 rotatable by a knob 6 into various positions so that the screen 2 may be illuminated to any degree from obscurity to full intensity. The inner surface of the shutter may be reflective. Near the lamp the housing has a glazed aperture 21 which is illuminated when the shutter 5 obscures the screen 2, and is obscured when the shutter permits full illumination of the screen. An apertured cowl 22 forms an air vent which prevents undue heating of a transparency laid against the window 21. A hinged cover, with reflective inner surface, when partially open permits viewing of an opaque print placed against the screen 2 ; it may be actuated either independently or from the shutter 5. Clips 26 serve to support the transparency or print against the screen. For roll films, spool holders may be provided. Adjustable opaque roller blinds 11, 14 prevent glare from the parts of the screen 2 not covered by the transparency. Ballast resistances and other lamp-controlling gear are enclosed in a casing mounted below the housing 1 and provided with a lamp switch 8.