Generation Mechanism of Unusual Noise in the Laser-Beam Printer.

Based on the investigation of the generation mechanism of the unusual noise generated from a laser-beam printer, it has become clear that self-excited vibration is produced due to the friction between the photosensitive drum and the cleaner blade, and the noise is its vibration noise. The vibration system is that of the tortional vibration of the drum, and the vibration mode is secondary. The self-excited vibration in the secondary vibration mode is caused by the drum structure and the friction force applied to the drum. This drum is made of a thin-walled cylinder having inertia on both ends. The friction force is applied uniformly and axially to the cylinder surface. In this case, the energy can be applied to the tortional vibration of the secondary vibration mode in the drum, and the existence of negative damping friction force results in the generation of the self-excited vibration. Since the vibration frequency is the audio frequency of 10.65kHz, it lies in the audible range. To prevent the vibration and the noise without affecting the function, appropriate and positive damping needs to be applied to the vibration system. Also, the method using friction loss is investigated and verified to evaluate its effect. This method proved to be effective, and it is confirmed that self-excited vibration is discarded, and the generation of unusual noise is completely eliminated. The generation pattern of vibration and noise described in this paper is not limited only to the laser-beam printer. In equipment such as plain paper copiers, liquid crystal printers and so on in which the same mechanical structure is required, the same phenomenon can occur. The cause and the countermeasure described in this paper are expected to be practically useful for development and design.