Patent GB-1218838-A (GB)
Title: Malfunction detection system for automatic film printers
IPC: G03B27/73
Filed: 1968-05-27
Abstract: 1,218,838. Programmed control; film strip printer; photographic materials processing. BELL & HOWELL CO. May 27, 1968 [May 26, 1967], No.25179/68. Headings G2C, G2A and G3N. An automatic photographic printer has vanes controlling the intensity of a light beam which are selectively actuated in dependence on signal from a storage medium and incorporates a checking device for determining actuation. In an additive colour printing system a beam of white light is split into red, green and blue light beams by an arrangement of dichroic mirrors. Each light beam is controlled in intensity by a pair of vanes positioned by a common gear 110, Fig. 5 aligned by V-shaped slots in a cylindrical member 54 coupled by a stud 98 to a member 96 displaced by the side-ways movement of a profiled member 70. Profiled members 60-70 are interconnected by rollers 72, which are vertically restrained, and are so shaped that on each being vertically moved by a rotary solenoid, such as 80, the cumulative side-ways movement is in predetermined multiples of a unit displacement. Each solenoid is biased to return to zero displacement by a spring 82 and latched in the downward position by an arm 84 and unlatched by a peg 90 on a bar 88 actuated by a spring-biased rotary solenoid 92. A solenoid arrangement not shown, for completely closing the vanes is coupled to a pin 124 on the member 54. Each profiled member is connected to a shield which, when the member is actuated, intercepts the flux between a reed switch and an associated magnet. Fig. 8 shows a circuit for detecting whether one of the reed switches 134 has been opened at a proper time whereby an indication is provided of whether a given slide has been properly actuated. A paper tape is coded with the required settings of the vanes, a hole corresponding to a slide which is to remain unactuated, and is read by a tapereader 42 and the information stored in memory relays, such as 141, 146, closed by a pulse on terminal C and opened by a pulse on terminal O. A cue signal is read from the master film by a reader 200 which delivers a pulse to a control circuit 40 which initiates advance and read-out of a reader 42, for successive lines on the tape denoting red, green and blue vane position values. When the memory relays are appropriately set, a delay device 176 causes the profiled members to be unlatched through a short delay device 182 and subsequently, through a delay device 174 the windings 160, 170 of the solenoids for the selected profiled members are pulsed in dependence on the state of memory relays 141, 146 through contacts 141a, 146a. The pulse from device 146 is also fed to a slow-acting relay 188 whose contacts 188a are only closed when the contacts of a reed switch 134-1, 134-6 are closed due to malfunction of a profiled member. The energization of relay 188 causes an error indication to be fed on line 198 and shown on an indicator 196. The vanes are positioned, in correspondence with the V-shaped slots in the cylindrical member, by energization, during the next control cycle, of a solenoid 108 through a delay device. It is stated that a separate relay 188 can be provided to indicate the malfunction of a particular profiled member. It is also stated that the punched tape can be replaced by a magnetic tape.