Proceedings of the British Kinematograph Society (1936)

Another form of continuous printer, used in laboratories in this country, is the Vinten rotary printer. The double unit, shown in Fig. 5, prints both picture and sound at a_ speed of one hundred feet per minute. The automatic light change is effected by means of a fibre chart 70 mm. wide, which runs at a speed one hundredth that of the nega tive to be printed (Fig. 6). The negative is graded by running the picture negative and the fibre chart upon a_ special machine in’ which the chart and the film run synchronously at their proper speed relation. A light change is effected by means of a punch hole in the chart, the position of the hole rela tive to the width of the chart determining “the printer light value. There are twentyone light changes. The Lawley continuous printer, having a printing speed of ninety feet per minute, is also much used in this country. In each printer, sound and picture are printed in two operations. Two printers are frequently coupled and operate as _ one machine to print both sound and picture simultaneously. For the printing of news releases (an operation requiring the minimum waste of time) the lay-out of one of the largest laboratories in this country permits them to print no less than eighteen copies of a subject with one handling of the negative. Light changes on these printers are effected by means of external resistances in. the lamp circuit, the changes themselves being made by an _ electromagnetic device operated by the Lawley system of nickel clips, which wrap between two perforations of the film, the distance between two clips indicating the light intensity. All the printers previously described have been of the continuous type. The most widely used intermittent printer in England and the Continent is the Debrie printer, shown,” in ~“Fig..-7, This machine, which has a continuous printing attachment for sound, prints picture and sound as a single operation. Light changes are made by externa] resistances in the lamp circuit effected by notches cut in the side of the negative at the appropriate position. Although not yet in use in this country, the latest Bell-Howell continuous printer, shown in Fig. 8, which prints both sound and picture as a_ single operation, deserves mention, because it embodies many new and_ practical features, amongst which is the means of | making light changes by using a specially prepared travelling matte that varies the light aperture opening, using a constant intensity light source.. This matte runs at one-quarter the speed of the film. Other features are the use of air pressure to ensure perfect contact at the printing aperture, the combination of compressed air and vacuum devices to clean the picture and sound negative and positive film while running, so that the printer can be run backwards and forwards without the necessity of removing the negatives at frequent intervals for cleaning. In fact, all the operator has to do is to thread the printer with positive stock, and the machine is so designed that if anything goes wrong the machine will automatically stop. Optical Printers There are other types and modifications of printers, notably those which have a series of printing gates so arranged that the same negative is printed simultaneously on to three or four different rolls of positive film. Probably the most interesting type of printer used in connection with motion picture film is the Optical Printer, the function of which is to produce various special effects, wipes dissolves, fades. Such printers are usually constructed to the requirements of the particular laboratory, and while the general principles involved are similar on all optical printers, there are many and devious ways of producing certain effects which are held by the laboratories as closely guarded secrets. To describe in detail a