Patent GB-1422460-A (GB)
Title: Method and apparatus for providing-indexing codes on movie  film and associated magnetic tape
IPC: G03B31/04
Filed: 1973-12-21
Abstract: 1422460 Indexing codes on cine-film LH O'DONNELL 21 Dec 1973 [29 Dec 1972] 59308/73 Heading G2E [Also in Divisions G4-6] A method of recording indexing information e.g. time indexing information on a cine-film comprises exposing edge portions of the film by a light source in a camera; the light source is controlled by a cyclical power generator having a period equal to at least two frame periods of the camera, power being supplied to the source for no more than one frame period so that each bit of indexing information is produced on one, or no more than two adjacent frames of the film. Format of time indexing information: The time is indexed every five seconds by exposing a strip along the edge of the film using a light emitting diode. The time is indexed in binary code, one bit occupying at least two frames of the film thus at a frame rate of 24 fr./sec the bits are applied at 12 bits/sec., giving a total of 60 bits/sec. In an alternative embodiment the LED provides four independent light beams to give a four track bit system. Camera and associated sound recording apparatus: The LED is controlled by a time index generator, a similar generator giving bursts of low frequency which are applied to the track of an associated sound recording. Thus the same information is recorded on both the film and sound track, the two generators being synchronized prior to filming to synchronize and pre-set them. Time index generator: Pulses from a 1.96608 MHz oscillator 15 are passed through divider circuits 17, 23, 25, 27 to give a pulse train of one pulse every five seconds. This pulse train is fed to counter divider circuits 29 to 37, arranged in series, which divide the pulses to give time units. Each circuit stores the incoming pulses it receives and also divides the pulses and feeds them to the following circuit. The five second pulse is also fed to a shift and enable connection so that every five seconds all the information contained in the counters 29 to 37 is shifted in parallel to stages 3 to 19 of the shift register. In the ensuing five seconds the information is shifted out of the register in series at a pulse rate of 12p/sec. and fed to the LED exposing the margin of the film. A similar circuit controls the information indexed on the magnetic tape. Calibration of time index generators: The generators are reset by clearing the counters and shift register and calibrating the counters by applying high frequency pulses from terminal 55 to counters 33 to 37. The desired time is dialled on a series of switches. An oscillator then supplies high frequency pulses to both the switches and the counters. When the number of pulses fed equals the number dialled on the switches a gate closes preventing further pulses being fed to the counters. The indexing information may be transferred from magnetic tape to magnetic film and the magnetic and cine films can then be edited. During editing the two films are wound from supply to take-up reels past detecting stations where the indexing information is read, decoded and displayed so that the cine and magnetic films can be synchronized.