Anti-strobing filters

Abstract

Several types of transmission filters are disclosed having specified transmittance functions to eliminate strobing in scanning an image through an aperture onto a photoreceptor. A general requirement or condition on photoreceptor irradiance profiles has been found to minimize strobing. photoreceptor irradiance profiles are generally the product of the time irradiance function of the periodically energized illuminating lamp and the spatial irradiance profile across the aperture near the photoreceptor. It has been found that strobing is eliminated if the Fourier transform of the spatial irradiance profile is zero, evaluated at the fundamental frequency of the illuminating lamp and at those multiples of the fundamental frequency at which the lamp has power. A transmission filter with predetermined transmittance characteristics therefore, can be disposed in the image path near the aperture to provide a spatial irradiance profile having a zero Fourier transform at the required spatial frequencies.

Dependencies are inferred from the claim text.