Patent GB-908863-A (GB)
Title: Variable-ratio drive for scanning arrangements and recording machines for image reproduction
IPC: H04N1/393
Filed: 1959-05-21
Abstract: 908,863. Copying by scanning. FAIRCHILD CAMERA & INSTRUMENT CORPORATION. May 21, 1959 [June 9, 1958], No. 17282/59. Class 40 (3). In an arrangement for the reproduction of an image of an original by means of rotatable drums co-operating with scanning and reproducing devices moved parallel to the axis of the transmitting and receiving drum respectively with first drive means for rotating a drum and second drive means for moving the scanning device in the axial direction, the second drum is rotated from the first drive means through a first supplementary drive means, the reproducing device is driven from the second driving means through a second supplementary drive means and at least one of the supplementary drive means includes a variable-ratio driving device in association with a member which is adjustable in a continuous manner for effecting a selected transmission ratio for said variableratio drive. As shown in Fig. 1, the shaft 16 of the recording drum 12 is rotated by a worm gear 30 driven by a worm 28 on the shaft 26 of the motor 24, and drives the shaft 14 of the transmitter drum 10 through a transmission arrangement 46. The reproducing carriage 20 is fed axially by a steel belt 42 passing round a pulley 40 secured to a worm wheel 38 rotated by a worm 36 driven from a worm 32 on the shaft 16. A pulley 44 rotated by the belt 42 drives via the transmission arrangement 46 a pulley 48 carrying a steel band 54 to which is secured the scanning carriage 18. The pulley 44 driven from the pulley 40 carries a gear-wheel 58 meshing with a gear 60 which rotates bevel wheel 64 of a differential 68, and which through gears 66, 74, 70 rotates a conical cam member 76 through one revolution during the axial traverse of the carriage 20. An axially movable rack 85 held against the cone 76 by a spring 86 rotates a gear-wheel 90 which is connected by a shaft 92 to an opposite bevel 100 of the differential 68, which is connected by a sleeve 102 to the bevel 104 of a second differential having its opposite bevel 108 connected by a sleeve 110 with the pulley 48 carrying the steel belt 54. The cone 76 can be moved axially, and if its location at a central position effects equal traverses of the carriages 18 and 20 its movement to the outer and inner positions will cause the carriage 18 to have an axial movement less or greater than that of the carriage 20. In a similar manner the rotation of drum 10 is controlled in relation to drum 12 by an adjustable conical cam 130 rotated from the shaft 16 through gears 112, 114, 118, 124, 126 so that it makes one revolution for each revolution of the drum 12, and moving a rack 138 rotating a gear 144 secured to the bevel gear 152 of a differential 122 of which the opposite bevel wheel 120 is rotated with the gear 114 driven from the shaft 16. The bevel wheel 152 is secured by a sleeve 154 to the bevel 156 of a second differential having its opposite bevel connected to a bevel wheel 160 driving a bevel 162 on the shaft 14 of the recording drum 10. The conical members 76, 130 may be adjusted simultaneously in the axial direction, Fig. 4 (not shown), by a yoke member having forked ends engaging the grooves 82, 136 and a central nut engaging a threaded shaft rotated by a knob 52. In an alternative arrangement, Fig. 6 (not shown), separate bifurcated members, each with a half nut engaging the threaded shaft, can be set independently and thereafter adjusted by rotation of the knob 52 so that different ratios of enlargement or reduction can be derived for the reproduction in relation to the original in two mutually perpendicular directions. Specification 692,349 and U.S.A. Specification 3,012,841 are referred to.