At Johnson &; In the Johnston case, the patentee Johnson &; Johnston company has a patent related to the manufacture of printed circuit boards, and its specification describes that the hard substrate of the circuit board is preferably aluminum, but it can also be stainless steel, polypropylene, etc. However, the hard substrate in the claims is defined as an aluminum plate. The products of the accused infringer R.E. Service Co., Ltd. use stainless steel substrate. In the judgment, CAFC held that when the applicant disclosed a theme in the specification, but did not ask for protection in the claim, it meant that the applicant donated the theme to the public. If it is still regarded as equivalent infringement in this case, it will lead to serious conflict with the function of defining the scope of protection in the claims. The court also pointed out that the applicant submitted a claim with a narrow scope of protection at the patent application stage, which easily passed the examination of the patent office. After obtaining the patent right, it is not allowed to claim that it constitutes equivalent infringement based on the equivalent characteristics disclosed in the specification. Finally, the infringement is not established.