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PER CENT OF INITIAL SIGNAL AFTER DARK PULSE OF }/20 SECOND
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SIGNAL-ELECTRODE VOLTS
Fig. 6. Relative "lag" of the vidicon signal as a function of signal-electrode voltage.
follows closely a simple power law, we can refer to the slope of the transfer characteristic on a log-lot plot as the "gamma" of the device. The curves of Fig. 7 show that the gamma of the vidicon is essentially constant at 0.65 over the entire range of signal-electrode voltages given. This is almost exactly the desired gamma characteristic needed to match positive motion-picture film to a kinescope transfer characteristic.
The overall transfer characteristic of such a system is slightly above unity gamma, which corresponds closely to current television-studio practice.
The photoconductive surface of a vidicon produces a very accurate and precise reproduction of a picture. Unlike other camera tubes it is not troubled by edging effects, electron redistribution, or flare, nor does the vidicon picture show any grain structure due to the
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HIGHLIGHT ILLUMINATION ON PHOTOCONDUCTIVE LAYERLUMENS
Fig. 7. Transfer characteristics of the 6326 vidicon at various signal-electrode voltages.
148
February 1954 Journal of the SMPTE Vol. 62