Patent GB-191218093-A (GB)
Title: Improvements in Photographic Cameras.
Inventor: LAKE WILLIAM EDWARD
IPC: G03B33/00
Filed: 1912-08-06
Granted: 1913-07-31
Abstract: 18,093. Lake, W. E., [Huebner-Bleistein Patents Co.]. Aug. 6. Colour photography; photo-mechanical printing- surfaces.-A camera for colour photography comprises (a) a fractional screen having a geometrically-arranged series of transparent and opaque units and adapted to rotate into successive positions, thereby exposing successively a determined fraction of the same or of successive plates; (b) a frame carrying three or more colour filters which are successively brought into position; (c) a shutter having means for automatically regulating the successive exposures through the separate filters; (d) an iris diaphragm with means for automatically regulating the aperture for successive exposures ; and (e) a holder for the sensitive plate or surface which can be automatically retracted from contact with the fractional screen, and repositioned for successive exposures. Means are provided for moving the different parts synchronously to make three successive exposures on one plate through three filters, the fractional screen causing one third of the surface to be exposed at each step. Alternatively (a) means are provided for arresting the mechanism at each step for the purpose of changing the plate and producing the successive exposures on different plates; (b) means are provided for keeping the colour filter, the fractional screen and the diaphragm stationary and for making successive exposures on the same or on different plates, through the same colour filter; (c) the colour filter may be disconnected and kept stationary, the rest of the mechanism being unaltered; (d) the fractional screen may be such that the transparent portions expose all but a fraction of the plate at each exposure. The camera comprises a front part A, Fig. 1, carrying the lens, shutter, filter, and diaphragm mechanisms, and is adjusted by a screw 40 to and from the back part B, which carries the fractional screen, the plate-holder, and the driving-mechanisms. The gearing for the parts associated with the front A are adapted. to slide on the main driving-shafts 57, 66. The driving-mechanism comprises two spring motors 70, 80, which drive the shafts 57, 66. The shaft 57 is driven continuously and carries a disk 90, Figs. 1 and 15, having a radial notch 91. The shaft 66 carries a disk 92 controlling three roller pins 94, which roll on the periphery of the disk 90. At each complete revolution of the shaft 57, one of the pins 94 enters the notch 91, and the shaft 66 is rotated by the motor 80 through a third of a revolution. This intermittent movement of the shaft 66 is used to move the fractional screen 157 and the filter carrier 140 into successive positions and to adjust the iris diaphragm 110 for each exposure, while the continuous rotation of the shaft 57 is used to actuate the shutter intermittently and to retract the plate from the fractional screen after each exposure. The roller pins 94 are secured to an annular plate 96,. Fig. 18, concentric with the disk 92 and connected by a bow-spring 97 which tends to hold the pins against the front ends of the slots 95 in the disk 92 through which they extend. This spring 97 cushions the impact of the rollers on the disk 90. The disks are secured against rotation by pawls 101, 103, which are simultaneously released by the spring boss 100 through gearing 105, 106, whereby also the disks are relocked only at the end of every complete revolution of the disk 92 when the complete set of exposures are made. The shutter 42, Figs. 1 and 3, is actuated from the shaft 57 by gearing 61, 62, 64, 65 and a cam wheel 46 which thereby makes one revolution for three of the shaft 57. The cam wheel carries three cams 49, which in turn raise a roller 45 through which the shutter is actuated, being reclosed by the action of the spring 48 and bellcrank 47. The cams 49 taper to a point and are adjusted longitudinally in dovetail guides 51, by screws 52, in order to adjust the period of contact with the roller 45 and thereby adjust the exposure. The cams carry pointers 53, which move over a scale indicating the exposure. The lens diaphragm 110, Fig. 1, is automatically adjusted for each exposure from the shaft 66 through gearing 133, 134, 136, 137, 138 and a shaft 125, Fig. 9, carrying three pins 117, which are radially adjustable and in turn determine the angular position of a spring arm 115 controlling the diaphragm. The colour filters are mounted in a circular frame 140, Fig. 1, and stud 141, and with a gear rim 145 meshing with the wheel 135, Fig. 9, which is in one with the wheel 134 and is intermittently moved by the shaft 66 and wheel 133. The fractional screen 157, Figs. 1 and 4, is composed of minute opaque and transparent areas such as 170, 171, Fig. 4<a>, which are arranged so that a different third of the sensitive surface is exposed in each of three angular positions into which the screen is intermittently moved by the shaft 66 through the gearing 156, 155, 154, 153. The latter wheel is on the screen frame 150, which is mounted within the bearing- frame 151 by guide-rollers 152. A spring bolt 158 prevents any circumferential displacement in the positions of rest, but yields when the frame is rotated. The plate-holder or dark-slide frame 182, Fig. 1, is mounted on longitudinal guides and is retracted to separate the plate 180 from the screen 157 just before the latter is rotated, by a cam 187 and a bell-crank lever 188. The holder is returned by a spring 185 into position which is determined by the stop 186 on the screw bolt 184. The dark-slide 181, Figs. 1 and 23, is protected at the opening in which it is inserted in the holder 182 by sliding plates 190, 191, which prevent light from entering at the side when the plate 180 is retracted, as shown in Fig. 23. The negatives produced comprise three records through the three filters. Each of these records can be printed separately by using the fractional screen in the taking positions, and the three reproductions used for obtaining printing-blocks for printing in colours' corresponding to the taking filters. The negatives can also be used for printing on to a support with colour areas corresponding to the arrangement of the fractional screen areas, by superposing the negative so that complementary colours on the base correspond with the colour units on the negative. Two or more than three colour filters may be used, in which case the mechanism and the unit areas of the screen are modified to correspond. Modified mechanism is described for different alternative purposes. (i) Successive records of the same colour can be made on the same plate or on separate plates by the modified mechanism shown in Fig. 27, by which the colour filters can be disconnected from the driving-mechanism. A loose wheel 204 is substituted for the fast wheel 133, Fig. 1, on the shaft 66 and is coupled by a bolt 207 extending from the loose sleeve 201. The sleeve 201 is driven by a coupling-disk 203 slidably keyed to the shaft 66 and is normally coupled by a spring 209 acting on the bolt 207. The colour filters are uncoupled by retracting the sleeve 201, which can be held retracted by a spring pawl 210 engaging one of three notches in the fixed hub 202 of the casing, the three notches corresponding to the positions of the filters. (ii) By the modified escapement mechanism shown in Fig. 34 any one of three operations can be performed. (1) The screen and colour filter may be operated automatically as in the first described form of apparatus. (2) The screen and colour filter can be rotated from one position to another automatically and stopped to allow a fresh plate to be exposed; or (3) the screen and colour filter are both stationary and a number of exposures can be made successively of the same colour and through the same screen. In lieu of the disk 92, Figs. 15 and 18, a three-part disk 216, 218, 220, Fig. 34, is used. The disk 220 has three spaced notches 221, and the disk 218 has one notch, corresponding to the notch 104 in the disk 92. The pawls 222, 215 are operated together by the release 232 through gearing 224, 225. The pawl 222 is adjustable along a slotted shaft 229 and is adjusted to engage the disk 218 when successive exposures are required, and with the disk 220 when the mechanism is to be arrested after each exposure to change a plate. In order to repeat an exposure through the same screen and colour filter, the shaft 66 actuating these parts is adapted to be locked by the pawl 222. This pawl 222 is releasably locked to the shaft 226 by a spring bolt in a spring-controlled handle 230, which normally engages the slot 229 in the shaft 226. When released from the slot, the pawl is disconnected from the shaft 226 and from the pawl 215, and the shaft 66 is locked under the influence of the spring-controlled handle 230.