Abstract: A sheet material feeding device comprises a sheet material housing part housing a sheet bundle having a plurality of sheet being stacked; a conveying-out unit press-contacting onto the front edge side of the upper surface of the sheet bundle to exert a push-out force, feeding a sheet by the push-out force in a predetermined conveying-out direction, and separating the sheet from the sheet bundle; a feeding unit arranged on the downstream side of the sheet material housing part along the conveying-out direction and continuing the feeding of the sheet, and after the conveying-out unit moves away from the rear edge of a preceding sheet, the conveying-out unit conveys a following sheet in a state that the following sheet is overlapped at the lower side of the preceding sheet until the front edge of the following sheet reaches a predetermined guide position set between the sheet bundle and the feeding unit.

Abstract: A sheet material feeding device comprises a sheet material housing part housing a sheet bundle having a plurality of sheet being stacked; a conveying-out unit press-contacting onto the front edge side of the upper surface of the sheet bundle to exert a push-out force, feeding a sheet by the push-out force in a predetermined conveying-out direction, and separating the sheet from the sheet bundle; a feeding unit arranged on the downstream side of the sheet material housing part along the conveying-out direction and continuing the feeding of the sheet, and after the conveying-out unit moves away from the rear edge of a preceding sheet, the conveying-out unit conveys a following sheet in a state that the following sheet is overlapped at the lower side of the preceding sheet until the front edge of the following sheet reaches a predetermined guide position set between the sheet bundle and the feeding unit.

Abstract: A noise masking system in an image forming apparatus such as a laser beam printer or a copying machine having a drive mechanism acting as a noise generation source during operation, the noise masking system comprising a masking sound generator for generating a sound to mask the noise and masking sound control device which controls the masking sound generator to generate a masking sound of a frequency range including a main-component frequency of the noise. The masking sound thus generated is of a frequency range from a lower-limit frequency to an upper-limit frequency in a critical band of the main-component frequency of the noise. The noise masking system masks noise without decreasing the sound pressure of the noise.

Abstract: A noise masking system in an image forming apparatus such as a laser beam printer or a copying machine having a drive mechanism acting as a noise generation source during operation, the noise masking system comprising a masking sound generator for generating a sound to mask the noise and masking sound control means which controls the masking sound generator to generate a masking sound of a frequency range including a main-component frequency of the noise. The masking sound thus generated is of a frequency range from a lower-limit frequency to an upper-limit frequency in a critical band of the main-component frequency of the noise. The noise masking system masks noise to eliminate a psychological unpleasant feeling caused by frequency fluctuation. It is small-sized and inexpensive.