In order to prevent water from leaking, a typical notebook computer cannot add a cooling fan to its main body:if a cooling fan is added, there will be a leakage problem in the ventilation hole.

    However, even in waterproof notebook computers, the most common use is in non-humid situations. For example, when using outdoors, the average person will still use it mostly under normal sunny or rainy conditions. Therefore, it does not seem to be economical to use a cooling fan in order to meet the needs of a few wet occasions.

  A new driving frequency switching device of cooling fan is designed to switch the running speed of CPU according to the fan action situation. and a waterproof notebook computer designed by using the device. The notebook computer is equipped with a cooling fan and a fan door.Under the control of the cooling fan driving frequency switching device, when the notebook computer is in normal use ( not wet ), the user can open the fan door and start the cooling fan to dissipate heat under the full-speed action of the CPU. When it is wet ( such as when it rains outdoors ), the user can close the fan door to stop the fan from rotating and drive the CPU to automatically reduce the frequency to prevent overheating.