Why is the effective date of the invention patent different from the start date of the invention patent term?

The invention patent right shall take effect as of the date of announcement, which refers to its publicity effect. So it is calculated by the announcement time. The term of the invention patent right shall be counted from the date of application.

patent law of the people's republic of china

Article 42 stipulates that the term of patent right for invention is 20 years, and the term of patent right for utility model and patent right for design is 10 years, counting from the date of application.

In addition, if the patent right continues to be renewed, it will also cause two different times.