Patent GB-715060-A (GB)
Title: Photographic contact printing apparatus for images in series
IPC: G03B27/16
Filed: 1951-11-27
Abstract: 715,060. Photographic contact-printing apparatus. FIX, W. Nov. 27. 1951 [Jan. 13, 1951; Jan. 19, 1951], No. 27754/51. Classes 98(1) and 98(2) A contact printing apparatus, especially one for prints from miniature camera films, has a printing window of such size as to allow printing two or more pictures at once and an equal number of individually adjustable light-intensity varying means capable of being arranged so that each is between a printing lamp and a separate original picture at the printing window so that by adjustment of each said means prior to simultaneous printing of the pictures the light which is passed by the original pictures is of substantially the same intensity in each case. As shown, between a printing window 12, adapted to accommodate three frames of a negative film strip 17, and a tubular lamp 4 are arranged on coaxial shafts 5 and 6, 7 (not shown) three cylindrical graded neutral density filters 8, 9, 10 each covering a window area equal to one film frame. The filters are separately adjustable by knurled wheels, each of which is engaged by a leaf spring opposing movement, until the three picture areas all have the same mean brightness, e.g. as compared with a grey window 13 of fixed brightness. The duration of the exposure may be controlled by a pre-set time switch 2 to enable two rows of three prints to be made on a single sheet, two levers 21, 22, casing 11 are provided with abutments 19, 20 respectively which are urged upwardly by springs 32, 33 and against which the edge of the sheet may be located alternatively with fixed stops 23, 24 on the casing. On alternate raisings of the platen 35 which is controlled by a snap-action toggle system including a spring 34, cams 28, 29 having a pair of oppositely disposed eccentric lobes and secured to a shaft 27 freely carrying the platen arms 26 are rotated 90 degrees by a pawl 31 on one platen arm driving a ratchet wheel 30 on the shaft 27 so that on alternate printings the abutments 19, 20 will project through slots 18 in the casing to locate the paper or will lie beneath the surface of the casing when the paper will be located by the abutments 23, 24, lowering of the platen may control the operation of the time switch. A peg 36 on the platen indents the paper at a point clear of the film so that the printed area may be readily identified. The printed sheet may be allowed to drop into a tray 25. In modifications, the presser platen frame may carry pins which pass through the surface of the casing and through ratchet and pawl devices raise or lower the positioning means at successive print-freeing movements-or actuate in turn consecutively mov.- able positioning means at different places on the print receiving face of the casing so that three or more series of prints can be produced. If desired the width of the picture may be varied by adjustable masking means for the printing window and a frame may be secured thereover to receive a magazine for a light-sensitive roll film. Instead of a negative strip film. separate negatives held together by a band or frame may be used.