The validity of Chinese patent ZL200780042463.2, entitled “heat curable resin composition for light reflection and the manufacturing process thereof, and the optical semiconductor element mounting substrate and optical semiconductor device using such resin composition”, was challenged before the China National Intellectual Property Administration (CNIPA), when the patentee attempted to enforce the patent at issue against an alleged infringer before the Beijing IP Court.

Claim 1 of the patent at issue protects a heat curable resin composition for light reflection, characterised in that:

the length of burrs generated during transfer molding at a molding temperature between 100 °C and 200 °C, under a molding pressure of no more than 20 MPa, and for a molding duration between 60 to 120 seconds, is no greater than 5 mm.

The interpretation of the length of burrs was the bone of contention in both the invalidity and civil infringement proceedings.

From the outset, the interpretation of claims originates from the court’s assessment of whether an alleged infringing technical solution falls into the scope of protection of a patent. However, the interpretation of claims is not unique to infringement disputes, as it is also necessary to interpret claims in patent prosecution procedures in order to ascertain the meaning and scope of the claims and their correlation with prior arts.

In principle, the judiciary often resort to description and appended drawings, relevant claims and the examination dossier of the patent at issue to interpret the claims. Where a terminology in the claims is specifically defined in the description, the definition shall prevail. Should the above means fail to elucidate the meaning of the claims, another option is to take into account known literature such as reference books, textbooks and the like, as well as the ordinary understanding by those skilled in the art.

The CNIPA’s Guidelines for Patent Examination explicitly provide in Part II, Chapter 2, Section 2.1.1 that:

The description shall use terms of the technical field to which the invention or utility model pertains. The description shall precisely express the technical contents of the invention or utility model without any ambiguity or equivocation that may prevent a person skilled in the art from understanding the invention or utility model clearly and properly.

The Guidelines further establish in Part II, Chapter 2, Section 3.2.2 the principle of how a claim should be understood:

The extent of protection of a claim shall be construed according to the meaning of the words used in the claim. Generally, the words used in a claim shall be understood as having the meaning that they normally have in the relevant art. In particular cases, where the description explicitly gives a certain word a special meaning and, by virtue of the definition to the word in the description, the extent of protection of the claim using the word is defined sufficiently clearly, such a case is also allowed.

Definition of the length of burrs in the patent description

Paragraph 0072 relates that, as used in the present invention, “burr length during molding” denotes the maximum length of resin-cured product that juts in the radial direction out of a centric cavity in a mold, through gaps at the joint between the upper dye and the lower dye of the mold, during the transfer molding process by using the mold for burr measurement, as illustrated in Figure 4.

Paragraphs 0139 and 0140 state that the mold for burr measurement comprises a pair of dyes, namely an upper dye 400 and a lower dye 401. The upper dye 400 has a resin sprue 402. The lower dye 401 comprises a cavity 403 opposing the resin sprue 402, and six slits 404, 405, 406, 407, 408 and 409 extending from the cavity 403 towards the outer periphery of the mold. The width of the six slits extending from the cavity 403 was five mm, and the depths were 75, 50, 30, 20, 10 and two µm respectively. As illustrated in Figure5, burrs are denoted as 410, which is formed by the resin composition that flows and is cured beyond the outer edge of the cavity 403, along the slits. The burr length specified in the present invention is the maximum value of the burrs denoted by reference numeral 410, measured by a caliper.

Inconsistency in the description

Based on the description, the length of burrs refers to the maximum length of resin composition that flows and is cured along the slits (ie, the six slits with different depths). However, that is not the case, as shown by the drawings. In Figure 5(b), the burrs are denoted as 410 and are marked between slits 407 and 408, rather than inside the slit. Figure 5(a) is also different from Figure 5(b): if the burrs refer to those denoted as 410 in Figure 5(b), which are between the slits, then they should be positioned above (rather than beneath) the upper surface of the lower dye in Figure 5(a). If the burrs refer to the cured portion inside the slits, considering all the slits are of certain depths and stretch to the outer edge of the lower dye, the lines denoting the depth of the slits should stretch to the outer edge of the lower dye instead of ending on the outer edge of 410. In a nutshell, Figure 5(a) is erroneous in either case.

Meaning of the length of burrs in prior art

Without universally acknowledged meaning in the art, the length of burrs is merely referred to in some Japanese patent literature.

In JP2007-119547A, the testing mold has slits of 2μm, 3μm, 5μm, 10μm, 20μm, 30μm and 50μm depths, and the length of burrs refers to the maximum length of resin composition cured inside the six slits (exclusive of the slit of 50μm depth).

In JPS56-149454A, the testing mold has slits of 100μm, 50μm, 30μm, 20μm and 10μm depths, and the lengths of burrs is measured in each slit.

In JPH07-179729A, the testing mold has slits of 10μm, 30μm, 50μm, 75μm and 100μm depths, and the length of burrs refers to the length inside the 75μm-depth slit.

The testing methodology of the length of burrsasdefinedby the description of the patent at issue is consistent with that mentioned in the prior arts, that is, testing the burrs inside the slits.

The collegiate panel of the China National Intellectual Property Administration (CNIPA) opined that clear expression of claims is vital in ascertaining the scope of protection of the patent at issue. A claim is devoid of clarity if a person skilled in the art does not have a clear and explicit understanding of the meaning of the terms used in a claim based on the text of the description and it thus becomes impossible to determine the scope of protection.

Regarding the length of burrs, Paragraph 0072 of the description fails to unequivocally acknowledge that the burr mentioned in the patent at issue refers to the seeped burr leaking through the gaps between the upper and lower dyes of the mould, as argued by the patentee, rather than the slit burr flowing inside the six slits. Paragraphs 0139 and 0140 of the description describe the burr as the cured portion that flows along the slits, rather than that seeping through the gap between the upper and lower dyes, as interpreted by the patentee. There are two portions in Figure 5 marked as 410. In Figure 5(b), the extended cured portion is obviously not the burr inside the six slits of the lower dye, but that formed between the fitting surface of the upper and lower dyes – this is likely the seeped burr alleged by the patentee.

As for the 410 marked in Figure 5(a), it would also be impossible for a person skilled in the art to ascertain without doubt that:

· the 410 here corresponds to the 410 shown in Figure 5(b), or

· the 410 here refers to the burrs inside the six slits of the lower dye.

The collegiate panel therefore concluded that the statement and definition of the length of burrs in the description lacked clarity and that a person skilled in the art cannot clearly and explicitly ascertain whether the length of burrs in claim 1 refers to those in the six slits of the lower dye or that of the seeped burr between the fitting surface of the upper and lower dyes as alleged by the patentee. The collegiate panel thus concluded that the scope of protection of claim 1 was not clear.

The CNIPA issued a ruling in invalidity decision 53229 invalidating the invention patent.

The patentee later withdrew the civil infringement suit.

Comment

The reason for the patentee’s inconsistent interpretation of the claims could be ascribed to the parallel infringement proceeding. Since claims are to be interpreted in accordance with the text of the description, the alleged infringing product will not fall into the scope of protection of the patent at issue. The patentee saw an opportunity in one marking of the drawing that might serve as a basis for an alternative interpretation and eventually led to the conclusion that the alleged infringing product fell into the scope of protection of the patent at issue.

Given that two of the aforesaid prior art relate to the patentee, the patentee must be well-versed regarding the meaning of the length of burrs in prior art. In the absence of explicit disclosure on any difference between the meaning of the length of burrs in the description of the patent at issue and that of prior art, it is evidently inadvisable to opt for a different interpretation of the term.

The invalidation of the patent at issue is an example of a patentee shooting themselves in the foot rather than a drafting misstep. If the patentee had stuck to the same interpretation of the length of burrs adopted by the prior art, the meaning would have been unequivocal. Even if the reference numeral 410 is marked between two slits, the burrs may be distributed along the whole periphery, not just on the mark of 410. In light of the greater gaps within the six slits, there will be more burrs inside the slits than between the slits and thus the maximum length of burrs will occur inside the slit. Since the length of burrs refers to their maximum length, which are denoted as 410, the meaning of the length of burrs will be consistent with the prior art.

It is highly likely that the invalidation of the patent at issue is the immediate consequence of the patentee’s arbitrary post-grant interpretation of the scope of protection, which is specifically prohibited by the Patent Law. The essence of the law is that the patentee exchanges voluntary disclosure for protection. If the patentee were to be allowed to broaden the scope of protection at will, this would result in the abuse of the patent right and thus be detrimental to the interests of the stakeholders and the public.

The case is a useful reminder that patentees need to tread carefully when exercising their rights to avoid any abuse.

Xiaoping Wu, first published by IAM