[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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When exposed to light, a gray background looks different in two cases : one where a white (positive polarity) figure is present in it, and the other where a black (negative polarity) figure is present. A psychophysical experiment is conduced to investigate how spatial frequency response corresponds to the above polarity-dependent appearances. Under high-contrast conditions, the positive-polarity spatial frequency response is a bandpass-filter type and the negative-polarity spatial frequency response is a low-pass-filter type. Under low-contrast conditions, the difference in response between the opposite polarities is insignificant. Morever, in each case, the response is the bandpass-filter type.

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The electron-beam divergence and current distribution of camera-tube diode-guns are studied experimentally and theoretically. This is done in consideration of the analytical results of the electron beam trajectory near the defining aperture of the diode-gun. It is found that the scattered electrons on the wall of the aperture hole increase beam divergence. For suppressing the beam divergence, a special double aperture and accelerating electrode formed into a conical shape are used. The electron beam divergences obtained are 0.3 to 0.65 degrees for G 1 voltages of 10 to 25 volts. They promise good resolution and low image lag characteristics for camera-tube applications.

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