None of the following shall be deemed as an infringement of patent right:

1. Where, after the sale of a patented product that was made or imported by the patentee or with the authorization of the patentee, or of a product that was directly obtained by using the patented process, any other person uses, offers to sell or sells that product;

2. Where, before the date of filing of the application for patent, any person who has already made the identical product, used the identical process, or made necessary preparations for its making or using, continues to make or use it within the original scope only;

3. Where any foreign means of transport which temporarily passes through the territory, territorial waters or territorial airspace of China uses the patent concerned, in accordance with any agreement concluded between the country to which the foreign means of transport belongs and China, or in accordance with any international treaty to which both countries are party, or on the basis of the principle of reciprocity, for its own needs, in its devices and installations;

4. Where any person uses the patent concerned solely for the purposes of scientific research and experimentation.

Any person who, for production and business purposes, uses or sells a patented product or a product that was directly obtained by using a patented process, without knowing that it was made and sold without the authorization of the patentee, shall not be liable to compensate for the damage of the patentee if he can prove that he obtains the product from a legitimate source.