GB899279A - Improvements in or relating to film projection control systems - Google Patents

Abstract

899,279. Kinematograph apparatus. ZEISS IKON A.G. March 26, 1959 [March 29, 1958], No. 10679/59. Class 97(1). In a film projection control system of the kind which includes a rotatably mounted member actuating according to a predetermined switching-programme, associated switches in circuits serving to control different processes in the film projection system, one of the control circuits serves to control drive to the member by means of a self-holding relay, the energizing circuit of which is normally completed through a switch of the relay and the switch of the said control circuit which is actuable by the member, the control circuit including additional switch means to complete an alternative energizing circuit through the relay which by-passes the relay switch when the member breaks the normally completed energizing circuit, so that in operation the member continues to rotate until the alternative circuit is broken by the member, and the member has reached a position in which it no longer affects the switch actuable by the member. In the preferred embodiment, a motor 6 drives a rotatable member or drum 5, having one of its control cams 5<SP>1</SP> arranged to engage a switch 1. During film projection, drum 5 and motor 6 are at rest, but near the end of the film, switch 4 is momentarily closed, and the coil 2 of the self-holding relay is energized, thus closing switch 2b in the said normal relay energizing circuit, and also switch 2a causing the motor 6 to rotate drum 5. When cam 5<SP>1</SP> engages switch arm 1<SP>1</SP>, the normal relay energizing circuit is broken, switches 2a and 2b are opened, and the motor stops; however the arrangement is such that the drum 5 continues to rotate until switch arm 1<SP>1</SP> reaches the position shown in broken line, when the alternative relay energizing circuit is completed through contact b. The switches 2a and 2b are again closed, and motor 6 again drives drum 5 until cam 5<SP>1</SP> releases arm 1<SP>1</SP>. Whilst arm 1<SP>1</SP> returns from contact b to a, due to the spring bias, switches 2a and 2b open, motor 6 stops, and the system returns to the rest position shown. During the period of rotation, the drum can be arranged to actuate associated switch or switches, for example to initiate the operation of another projector. Specifications 850,561 and 899,278 are referred to.