Modeling and analysis of notebook computer chassis structure for optimization of component mounting

As one of the most important components in notebook personal computers, the chassis is critical for the performance reliability and robustness of the computer as well as the hard disk drive (HDD). An appropriate chassis structure is able to effectively reduce the position error signal (PES) of HDD induced by the built-in vibration sources, including the speaker, cooling fan and CD/DVD driver, transmitted to the HDD via the chassis. Therefore, it is important to study the vibration transmission from the various sources to HDD in order to isolate the external disturbance through optimization of chassis structure. This paper presents a theoretical model to analyze the vibration transmission from the speaker, cooling fan and CD/DVD driver to the HDD, where the governing equations describing the vibration transmission are formulated and their solutions are developed. The characteristics of transmission are demonstrated in the transfer function forms, which provide an effective approach to the analysis of the chassis of notebook computer. The routes of transmission in the model are then investigated in detail to provide a basic understanding and general design rule for the notebook computer and chassis regarding transmissibility of vibration. Furthermore, the results of the theoretical model are verified by the frequency analysis of the notebook computers, and an investigation of the vibration transmission from the vibration sources to the HDD is performed in detail. In addition, the solution is also proposed to reduce the external disturbance on HDD through optimization of chassis. This study provides a simple and an effective approach for chassis design to reduce the vibration transmission to HDD in notebook computers.