Recently, the Korean Supreme Court held that when it is possible to determine the technical scope based on the patent claims alone, the scope of patent protection cannot be restricted or reduced by using other disclosures contained in the specification (Case No. 2017Da231829 rendered on January 14, 2021).

▶Facts of the Case

Korean Patent No. 905128 (“The subject patent”) relates to a contamination prevention device for use in a self-plasma chamber employed during a deposition process. Claim 1 and Fig. 1 of the subject patent are as follows:  

Claim 1.

  A contamination prevention device for a self-plasma chamber, the self-plasma chamber being connected to an exhaust pipe of a process chamber and having a space in which a gas inside the process chamber is introduced to form a plasma state, comprising: 

 an electromagnetic field generation unit to generate an electromagnetic field so that a contaminant introduced from the process chamber deviates from a straight path toward a window of the self-plasma chamber; and 

 at least one barrier having a through-hole formed in a center thereof so that an optical signal from the self-plasma chamber reaches the window through the straight path, wherein the at least one barrier blocks the contaminant deviated from the straight path by the generated electromagnetic field from reaching the window of the self-plasma chamber.

                                              [Fig. 1]

The Patentee-plaintiff filed an infringement action based on the subject patent against Defendant. Defendant argued that their accused product did not infringe the subject patent because in their product, barriers were formed inside the magnetic body, whereas the barrier of the patented invention, as shown in the drawings of the specification, should be construed to be formed separately from and behind the electromagnetic field generation unit. 

▶Patent Court Decision 

The Patent Court noted that the detailed description, as well as claim 1, simply states that the barrier blocks the contaminant from reaching the window of the chamber and does not mention any limitation on the position of the barrier. The Patent Court also noted that the drawing of the subject patent, shown above, is merely an exemplary embodiment and, under the principle of claim interpretation, cannot be used to restrict or reduce the scope of protection of the patented invention. Consequently, the Patent Court rejected the Defendant’s non-infringement argument, built on the narrow interpretation of the position of the barrier as shown in the drawing of the subject patent. 

▶Supreme Court Decision 

On appeal, the Supreme Court first reaffirmed the principle of claim interpretation, as follows: 

As a matter of principle, the scope of protection of a patented invention shall be determined by the elements described in the claim. When the claim wording alone does not render it possible to determine the technical constitution or scope, other disclosures in the specification can be used to remedy the deficiency; however, in such an event, said “other disclosure” cannot be used to expand the scope of protection beyond the realm of the claim. Further, when it is possible to determine the technical scope based on the claim alone, the scope of patent protection cannot be reduced by using other disclosures in the specification (see, e.g., Supreme Court Case No. 2010 Hu 2377 rendered on February 10, 2011).  

In accordance with the above principle, therefore, the Supreme Court upheld the Patent Court’s decision that the scope of protection of claim 1 is not limited to an embodiment in which the barrier is spatially positioned behind the electromagnetic field generation unit, and reiterated that disclosures relating to preferred embodiments or exemplary drawings given in the patent specification cannot be used as a basis for limiting the scope of protection of the patent claim. Accordingly, the Supreme Court dismissed the Defendant’s appeal.