Legal analysis: the single principle of patent application means that a patent application is limited to one invention. An application for a patent for an invention or utility model shall be limited to one invention or utility model. Two or more inventions or utility models belonging to a general inventive concept may be filed as one application. An application for a patent for design shall be limited to one design. Two or more similar designs of the same product, or two or more designs of products used in the same category and sold or used in sets, may be filed as one application.
Legal basis: Article 31 of the Patent Law of People's Republic of China (PRC). An application for a patent for an invention or utility model shall be limited to one invention or utility model. Two or more inventions or utility models belonging to a general inventive concept may be filed as one application. An application for a patent for design shall be limited to one design. Two or more similar designs of the same product, or two or more designs of products used in the same category and sold or used in sets, may be filed as one application.