This paper identifies the root cause of noise in corona devices and proposes three different approaches to solve the problem. In an electro-photographic printing machine, corona devices are placed adjacent to a photoconductive surface to perform various functions. These functions vary from charging the photoconductive surface, to transferring an image, to detaching a paper from the photoconductive surface. A corona device is usually a wire mounted under tension in a housing. In some cases, the wire is coated with a dielectric material like glass to improve the charging function. A perforated metal may also be placed between the wire and the photoconductive surface to enhance function. Under drastic conditions, both the corona device and the power supply could emit noise. However, we focus on the corona device in this paper. Beyond broadband noise, pure tones at the charged frequency and its harmonics could be annoying. Sound power level over 8.5 bel is not unrealistic. Broadband noise is caused by the corona effect. Attraction and repulsion of AC current in the corona generates pure tone. Noise emission due to vibration of the wire and noise radiation by the corona housing is insignificant. Three solutions were developed. They are noise control by steering, masking, and absorption. These solutions can be implemented independently or simultaneously to gain maximum attenuation. Each of these solutions provides up to 13 dB of noise attenuation.
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