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

istics desired for television broadcast use. Its outstanding features are high signal-to-noise ratio, "built-in" gamma of the proper magnitude, accurate black-level reproduction, excellent resolution, and freedom from spurious signals. The tube is also outstanding in its ease of operation and usefulness for nonsynchronous operation. It is felt that the new vidicon provides the best solution to date for the problem of film reproduction on television. Acknowledgments Acknowledgments are due to Robert B. Toppmeyer and F. David Marschka of the RCA Tube Dept., Lancaster, Pa., for assisting in the evaluation of the performance and quality characteristics of the vidicon for this application ; and to B. H. Vine, also of the RCA Tube Dept., who did most of the basic design work on the tube and suggested a number of the operating procedures. H. N. Kozanowski and E. M. Gore of the RCA Engineering Products Dept., Camden, N.J., have also contributed much valuable information based on their work in developing a film-camera chain for the 6326 vidicon. APPENDIX Horizontal Amplitude Response: In this paper this term represents the measured peakto-peak signal developed from a squarewave test pattern resolution wedge. This type of test is used more than any other for evaluating the resolving capabilities of a camera tube. Equivalent Amplitude Response: This is the geometric mean of the horizontal resolution and the vertical resolution (both expressed in numbers of picture lines). It is expressed as Req = \/Rv X Rh where Rv and Rh are the vertical and horizontal resolutions, respectively. Signal-to-Noise Ratio: The term "visual equivalent signal-to-noise ratio" has been coined for this presentation. Since the vidicon signal is applied to a peaked amplifier, the noise of the camera video signal is concentrated at the high end of the transmitted band. This high-frequency noise is not as apparent to the eye as the lowerfrequency noise components. As a result, for a 4.5-mc bandwidth the peak signal-to-rms noise ratio can be multiplied by a factor of approximately three to obtain the visual equivalent signal-tonoise ratio.2 This is not true, however, of the image orthicon, which produces so-called "flat noise" having equal energy distribution throughout the bandwidth. Gamma: This property of the transfer characteristic of a transducer such as a camera tube is obtained from the equation Is = Ei^ where I8 is the signal output, Ei is the incident illumination, and 7, or gamma, is the exponent. References 1. B. H. Vine, R. B. Janes, and F. S. Veith, "Performance of the vidicon, a developmental camera tube," RCA Rev., 13, No. 7: Mar. 1952. 2. O. H. Schade, "Electro-optical characteristics of television systems, Part III," RCA Rev., P, No. 3: Sept. 1948. Discussion James H. Ramsay (Philco Corp.}: Is there another vidicon tube different from this one? Mr. Neuhauser: There is a vidicon tube that was developed for the industrial market. That is the 6198, from which this one, the 6326, has actually evolved. The 6326 has a different gun structure and it is processed differently. Mr. Ramsay: Could you go into much detail on the differences between the two? Mr. Neuhauser: The differences are mostly in the gun structure and in the care and testing and processing, as well as in the quality limits. Mr. Ramsay: The previous one, the 6198, did not have the dynamic focusing on it? Mr. Neuhauser: That's correct. There was no dynamic-focusing electrode in the 6198. There is in this tube. Neuhauser: Vidicon for Film Pickup 151