(1) Field of the invention
The present invention generally relates to an image forming apparatus, such as a copy machine, a facsimile machine or a printer, and more particularly to an image forming apparatus having a system for reducing noise caused by operation of the image forming apparatus in a predetermined space.
(2) Description of related art
In, for example, a copy machine (an image forming apparatus), an image receptor body (a photosensitive member) on which latent images can be formed, a developing unit for developing latent images on the image receptor body, a transfer unit for transferring a visible image obtained by the developing unit from the image receptor body to a transfer material (a recording sheet) and so on are housed in a main body. In addition, the main body of the copy machine can be integrated with peripheral equipments, such as an automatic document feeder unit, a sorter unit, a stapler unit, and the like. Thus, when the image forming apparatus such as the copy machine is being operated, various noises can be generated therefrom.
In the main body of the copy machine, there are vibrations caused by a rotation of a main motor for driving various mechanisms therein, noises generated when papers are fed by rollers, noises generated when developer is agitated in the developing unit, and the like. In a sorter unit, there are noises generated when feed rollers are rotated and noises generated when papers are set in bins in the sorter unit. In a stapler unit, there are noises generated when papers are stapled. The above noises generated in the main body of the copy machine and the peripheral equipments integrated with the main body are radiated from them via openings used for heat radiation and for ejecting papers.
Conventionally, a sound arrestor of an impact printer has been disclosed in Japanese Patent Laid Open No. 61-262166. In the sound arrestor disclosed in the reference, a noise generated by a printer head is canceled by an acoustic wave having a phase inverse to the noise.
In addition, the applicant has been proposed an apparatus in which the noise generated in a machine is canceled by an acoustic wave having a phase inverse to that of the noise, in U.S. patent application Ser. Nos. 810,169 and 851,375.
However, a position at which a loudspeaker outputting an acoustic wave for canceling the noise generated by a machine is mounted is not related to an area in which an operator is positioned when operating the machine. Thus, the noise generated in the machine is not always effectively reduced for the operator of the machine.
Further, in an image forming apparatus, such as a copy machine, an area in which the operator may be positioned varies in accordance with operation mode. For example, an area in which the operator may be positioned in a normal copy mode differ from that in which the operator may be positioned in an operation mode using the sorter unit.
An image forming apparatus, such as a copy machine, is set up in an office. In this case, it is desirable that noises caused by the copy machine be effectively reduced in an area, in which persons work, remote from the copy machine.