Journal of the Society of Motion Picture and Television Engineers (1950-1954)

bare minimum of monitoring and adjustments, a practical reality. This is believed to be of great importance to the television broadcaster. This paper up to the present moment encroaches on the territory which is normally the province of the pickuptube development engineer. However, tube and camera performance are so intimately related that it is practically impossible to draw a sharp dividing line between the two activities and still present an informative picture of developments and progress. Features of Vidicon Camera Design The vidicon camera system, which will now be described, is the third model resulting from information acquired in the advance development phases of the study. The general philosophy of approach was based on the following goals: 1. The camera itself should be as small as possible so that it can be mounted directly on either a 16mm or 35mm projector or integrated into an optical multiplexing system. 2. The control circuits should be rack mounted for ease of maintenance and performance check. This has obvious advantages over locating them in a chassis set in a desk-type operating console, with poor accessibility. 3. The control panel containing the various operating and setup controls should be capable of location remote from the rack, should contain no electron tubes, and its connecting cables should not carry any signals except variable d-c voltages. Following this approach, the camera contains only the vidicon tube, focus and deflection coils, a high-performance cascode amplifier, a low-impedance video output stage and a vidicon blanking amplifier. Since the deflection requirements are relatively modest, horizontal deflection is supplied to the camera from a rack mounted deflection amplifier through a coaxial conductor in the standard camera cable. A constant resistance termination is used, with the horizontal deflection coils as one of the termination elements. Suitable circuits are used for protection of the vidicon tube in the event of scanning failure. Regulated focus field current and other required operating waveforms are supplied to the camera from the rack chassis by conventional methods. Other elements of the rack chassis assembly perform such functions as high-peaking to compensate for the effect of vidicon input shunt capacity, aperture compensation,5 final blanking, clamping, clipping and addition of synchronizing signals. A standard RMA signal of 1.0 v is produced across the usual 75-ohm coaxial distribution line. Figure 1 is a block diagram of the essential portions of the system. A vidicon camera mounted directly on a TP-6A 16mm Projector is shown in Fig. 2, and Fig. 3 is a detailed view of the vidicon camera. Figure 4 shows the general appearance of the junction chassis; the focus, deflection, and protection assembly; the final processing amplifier; and the control panel. In an actual operational installation, all of the units except the control panel are mounted in a standard broadcast-type rack and are interconnected by suitable plugs and cables. The control panel is usually installed horizontally below a master monitor for convenience in operation. Television Film Projectors It can be mentioned that the vidicon, because of its well-behaved storage characteristics, can be used with any projector, continuous or intermittent, with long or short-application time, which has suitable television conversion features. These are implied in the requirement of translating 24 film frames/sec into 30 complete television Kozanowski: Vidicon Cameras 157