Patent GB-682071-A (GB)
Title: Improvements relating to photographic enlargers
IPC: G03B27/68
Filed: 1949-04-29
Abstract: 682,071. Photographic enlarging apparatus. PULLIN OPTICALCO., Ltd., BAUMGARTNER, W. J., and GOSS, R. H. May 1, 1950 [April 29, 1949; Sept. 5, 1949], Nos. 11528/49 and 22968/49. Class 98 (i). The optical system of a photographic enlarger is adjustable about two mutually perpendicular axes, one of which is always perpendicular to the optical axis of the optical system, and the second of which is always parallel to the plane in which the sensitive material on which the enlargement is made is supported. When the optical system is supported, slidably or otherwise, on a column, the first axis and the axis of the column may lie in a plane to which the second axis is perpendicular. As shown, Fig. 2, the lamphouse 37, condenser housing 41 and lens board 51 of an enlarger are carried by a bracket 1 slidable on a vertical column 2. A lever 22 is pivoted at 23 between divided rearward extensions of the bracket 1, and is urged outward by a spring 25 so that a projection 26 at its lower end bites into column 2 to hold the bracket thereon. When the bracket is gripped by hand, lever 22 is pushed in to allow the bracket to move freely along the column. Alternatively, two levers such as 22 may be pivoted, one at each end of the bracket. The bracket has forwardly projecting arms 3, 4. A casting 6 is pivoted at 5 to arm 3, and a rod 7 is oppositely threaded at its ends into shafts 10; 11 trunnioned in casting 6 and arm 4 respectively, so that on turning the rod by its milled head 14 casting 6 is rocked in a vertical plane, the extent of the rotation being indicated on a scale 15. The optical system has a rod 28 which slides into a sleeve 27 formed in the casting 6, and can thus be tilted about a horizontal axis at right-angles to the pivot 5, the extent of the tilt being indicated on a scale 32. A clamping knob 31 is threaded on a shaft passing through lugs on sleeve 27. A casting 34 carried by rod 28 supports the negative carrier 38 having wire film supports (not shown) and has extending therethrough a pair of parallel guide rods, of which rod 35 is formed with rack teeth. The condenser housing 41 is guided on the rods, and the lamphouse 37, which has cooling fins 47 and houses a lamp fed by an electrical cable 21 passing through column 2, is attached to the condenser unit by spring clips. A rod journalled in the condenser housing has a pinion engaging the rack teeth on rod 35, so that when this rod is rotated by a knob the condenser and lamphouse are lifted for the insertion of a negative. The lens board 51, carrying the objective-lens and connected by bellows 52 to the casting 34, is moved along the guide rods by a shaft carrying a knob 54 and a pinion engaging the rack teeth on rod 35, and having enough friction to prevent movement except by the operator. When the optical system is tilted, e.g. to correct converging verticals in a negative, the lens board should also be tilted so that its plane may intersect the planes of the negative and of the baseboard in a common line. A modification therefore includes means for tilting the lens board about mutually perpendicular axes. As shown in Fig. 8, the lens board is divided into two parts, and a T-shaped member 70 is journalled in the part 51 moving on the guide rods, and has lugs 69 carrying a pin 63, which passes also through lugs 68 on the part 51a of the lens board carrying the lens, and through a cross-piece attached to a pin 64 journalled in member 70 and having a threaded end engaged by a milled nut 67. The lens board can thus be tilted as desired, and clamped by means of the nut 67.