Patent protection: does it promote or inhibit the patented technological knowledge diffusion?

Patents not only promote the dissemination of technological knowledge through the disclosure of innovative information, but restrict the use of patented technology by the public within the scope of the law. With this exclusive protection on the premise of information disclosure, it is ambiguous whether patents help or hinder the diffusion of knowledge within the span of patents. This study first constructs a multidimensional index of patented technological knowledge diffusion (PTKD) from spatiotemporal aspects, and compares the differences in technological knowledge diffusion of four types of patents—valid patent (VP), zero-cited patent before expiration (Z-B), zero-cited patent after expiration (Z-A), and non-zero-cited patent before and after expiration (NZ-BA). Then, the impact of patent protection—patent lifetime (PL), the number of independent claims (NIC), the number of words in the first independent claim (NWF)—on the degree of PTKD is explored. The results demonstrate that NZ-BA has the highest level of PTKD in terms of growth rate, technological and geographical breadth and depth, followed by VP. Meanwhile, PL affects the diffusion growth rate and technological and geographical breadth negatively, NIC positively affects the diffusion average speed and technological and geographical depth while NWF only positively affects the technological depth of diffusion. These findings highlight the role of different types of patents in promoting technological innovation and promote a better understanding of the correlation between patent protection and PTKD, which provides support for decision-makers to protect property protection and guides the patentees to protect their long-term economic and technological benefits.