Technology for Sound Source Analysis
It has been increasingly necessary to provide low-noise products in order to comply with noise requirements such as those set for achieving the Blue Angel Mark and provide a more comfortable workplace environment.
Unlike home electric appliances and automobiles, multifunctional machines and printers have different types of complexly concentrated sound sources, along with non-stationary noise emissions from clutch operations, paper transport, and other operations. However, it is difficult to identify the scale and location of non-stationary noise sources using typical measurements with a microphone or noise intensity distribution. Therefore, a new approach to analyzing noise reduction has been requested.
Fuji Xerox has now newly developed the "Proximity microphone array system" that enables the measurement and analysis of non-stationary noise (impulse sounds) emanating from multifunctional machines and printers. As a result, Fuji Xerox is now able to accurately measure and analyze the noise scale and location of a sound source, leading to top-level noise reduction in the industry.
This method analyzes noise by using a device that can collectively measure sound distribution with a set of numerous microphone s as shown in Fig. 1. Moreover, as shown in Fig. 2, the method employs proximity microphone arrays that can vary the installation distance of each microphone according to the uneven surface of the target machine, in order to accurately determine the noise scale and find the location of the sound source.
This device enables the optimum setting of equally maintained distance between each sound source and each microphone, thereby eliminating the influence of sound interference and an uneven machine surface, and making it possible to identify noise sources with higher accuracy than with existing technology.
In the actual analysis of impact sounds emanating from clutch operation of the paper-handling drive system on a multifunctional machine, the largest impact sound was found to originate from the cover of the left-of-center clutch unit to which the sound is transmitted, and not from the clutch area. Fuji Xerox used to investigate the design and operation of the clutch itself, but now this system enables noise control in terms of sound transmission and emission, thus largely contributing to noise reduction.