R&D strategy for building effective entry barrier

As Michael Porter described [4], entry barriers can be reduced due to the expiration of basic patent rights. Therefore, many companies try to build effective entry barriers by creating effective patent portfolios in order to deter new entrants from plunging into existing and/or emerging markets. The aim of this study is two-fold. First, we focus on the research framework by taking the perspective of the patent life cycle (PLC) model, which has been sophisticated by the "underlying specification" that is the evolution of "the dominant design" introduced by Abernathy and Utterback [1]. Second, we reveal the effective cooperation between R&D strategy and patent strategy in order to build a continuous entry barrier. The conclusions of our study are as follows: First, two or more derived products with similarities to an existing product structure were developed concurrently by the same company during the growth stage of the existing product, so as not to allow a time period without patent rights. The results of the development were used with the existing product. Second, it was necessary for an existing inventor and a new inventor to take part in the derivation product development simultaneously in order to utilize the results of new product development with the existing product. Third, according to the PLC analysis, the effective cooperation between R&D and patent division was crucial in both "the piezoelectric elements" and "the diesel particulate filter".