For invention patents, there must be a description that clearly and completely describes the technical solution, and the claims clearly state the scope of the technical solution requested for protection. Even if there is only an idea, if a person skilled in the art can clearly understand what the technical solution is based on the description, the accompanying drawings are not required.
For a utility model patent, it must be an improvement on the shape and structure of the product, so there must be drawings.
For design patents, pictures are also required, and pictures are used to determine the scope of protection.