GB884342A - Illuminating apparatus for photographic printers and enlargers - Google Patents

Abstract

884,342. Photographic illuminating apparatus. SIMMON BROS. Inc. Jan. 29, 1960 [Feb. 1959], No. 3263/60. Classes 97(1) and 98(1). An illuminating apparatus for photographic printers and enlargers adapted to illuminate a photographic negative or transparency comprises a source of light 13, a light collector 20 partly surrounding said light source having an orifice 11 and being arranged to project the greater percentage of the light admitted by said source light through said orifice in a form having a substantially uniform intensity distribution over the area of the orifice and a mixing chamber comprising a hollow body with a diffusely reflecting interior surface and having two apertures, the first aperture 45 being substantially the same size as said orifice and disposed in juxtaposition thereto to admit light passing through said orifice into said mixing chamber, and the second aperture 48 being disposed in the wall of said hollow body at an angle to said first aperture and being at least as large as the photographic negative or transparency 53 which is to be placed therein whereby such photographic negative or transparency is completely illuminated by diffused light of high intensity which is substantially uniformly distributed over the area of said photographic negative or transparency. In the apparatus shown two light collectors 20 are provided, the internal specularly reflecting surface of each being generated by rotating an ellipse about an axis inclined at a small angle to its major axis and passing through one of its focal points 12. A housing member 24 is interposed between each light collector 20 and the mixing chamber 44 and contains a disc shaped infra red filter 25 continuously rotatable about hub 26 by a motor 28 when lamp 13 is energized, a fixed infra red filter 29, and three filters 30, 32 and 33 respectively of colours cyan, yellow and magenta and respectively adjustable by knobs 38, 42 and 39 through a lever linkage shown in Fig. 4 in which links 34, 43 and 35<SP>11</SP> are rigidly connected for control to the shafts of the said knobs and the other links are freely pivoted thereon. In the aperture 48 there is provided a diffusing sheet. 54 and a film holder 52 for supporting the negative 53. In modifications more (or less) light collectors may be used.