Examination of inventive step and three-step method
It is paramount in a patent examination to determine whether an invention involves an inventive step. According to Article 22.3 of the Patent Law, two requirements are necessary to show the inventive step of an invention compared with the prior art:
- the invention must have prominent substantive features; and
- the invention must represent notable progress.
The typical approach to the assessment of prominent substantive features – the so-called ‘three-step method’ – is provided in the Guidelines for Patent Examination 2010 (published by the Chinese Patent Office), as follows:
- determine the closest prior art;
- determine the distinguishing technical features of the invention and the technical problem actually solved by the invention; and
- determine whether the claimed invention is obvious to a person skilled in the art.
In practice, both patent examiners and patent attorneys usually use the three-step method to determine whether an invention involves an inventive step. But is the three-step method the only test available to ascertain the inventive step of an invention? And if the method is not applied, will the patent examination result in a false conclusion?
Beijing Intellectual Property Court case
Decision 25568 regarding the invalidation procedure issued by the National Intellectual Property Administration’s Patent Re-examination Board for Invention Patent 02805525.X (transparent substrate equipped with electrode) was appealed by the plaintiff to the Beijing Intellectual Property Court (ie, the first-instance court).
One of the plaintiff’s arguments was that the Patent Re-examination Board did not apply the three-step method specified in the guidelines when determining whether the claims of the patent at issue involved an inventive step. This led to a conclusion of non-obviousness of the claims. The plaintiff believed that the board applied the wrong method, which inevitably resulted in the wrong conclusion.
The patent at issue disclosed a transparent substrate equipped with an electrode that can be used as a part of a solar cell. The invention of this patent aims to simplify the production process of the transparent substrate and/or make its production costs lower than that of existing molybdenum electrodes, while making no significant change to performance (particularly electrical performance).
A transparent substrate is equipped with an electrode and compresses a molybdenum-based conductive layer with a thickness of up to 500 nanometres (nm). Its particular characterisation lies in the fact that the substrate is equipped with at least one barrier layer. This layer provides a barrier against alkali metals and is inserted between the substrate and the electrode (see Schematic Diagram 1). The barrier layer must be based on a dielectric material made from at least one of the following compounds:
- silicon nitride or oxynitride;
- aluminum nitride or oxynitride; or
- silicon oxide or oxycarbide.
The barrier’s thickness must be between 120nm and 300nm.
The patent at issue states that the molybdenum target is expensive. The alkali metal elements in the substrate can be harmful to the molybdenum base and a barrier layer must therefore be inserted between the molybdenum-based electrically conductive layer and the substrate to prevent the alkali metal elements in the substrate from diffusing and eroding the molybdenum base (and the absorbent layer). This should mean that the molybdenum base in the electrically conductive layer will retain all its properties and the thickness of the molybdenum base that must be used in the transparent substrate can be reduced.
The plaintiff submitted evidence including references D1 (The Influence of Na on the Growth of Gu(In,Ga)Se2 Layers for Thin Film Solar Cell”, Karin Granath 1999) and D2 (US patent US4485146A) in both the invalidation and litigation phases. D1 (the prior art closest to the patent at issue) disclosed that sodium (one of the alkali metal elements) can have a beneficial effect on the structural characteristics of the copper indium gallium selenide (CIGS) substrate absorbing layer, including:
- increasing the grain size;
- flattening the surface; and
- exerting beneficial effects on the electrical characteristics.
There are two ways to supply sodium to the CIGS layer:
- supply sodium from the soda lime glass substrate through the molybdenum thin film (see Schematic Diagram 2a); or
- deposit the sodium precursor on the molybdenum thin film and then supply sodium to the CIGS layer deposited on the sodium precursor (see Schematic Diagram 2b).
In order to study the influence of sodium on the CIGS layer, D1 uses a variety of thin-film solar cell construction methods (including four structures: a, b, c and d); wherein, in Structure d, it uses a sodium diffusion barrier layer to form a structure without the sodium substrate (see Schematic Diagram 2c).
According to D1, in Structure d, the above two ways to supply sodium to the CIGS layer (ie, the two supply modes shown in Diagrams 2a and 2b) are blocked by the sodium diffusion barrier layer, resulting in no crystal structure being found in the CIGS layer. Therefore, D1 evidence concludes that if the CIGS layer is not supplemented with sodium, then it is unlikely to grow an effective CIGS crystallisation layer. However, as long as the CIGS layer is supplemented with sodium, the growth effect will be enhanced.In order to study the influence of sodium on the CIGS layer, D1 uses a variety of thin-film solar cell construction methods (including four structures: a, b, c and d); wherein, in Structure d, it uses a sodium diffusion barrier layer to form a structure without the sodium substrate (see Schematic Diagram 2c).
D2 discloses a solar cell. It also discloses that alkali metal ions which have leaked from the electrode may diffuse into the amorphous silicon, resulting in a decrease of conversion efficiency and meaning that a silicon oxide layer film may be formed on the surface of the soda lime glass to prevent diffusion of alkali metal ions.
The court pointed out that, in its opinion, the purpose of the barrier layer in Claim 1 is to block the sodium from entering the molybdenum-based conductive layer and the absorbent layer, thereby preventing the sodium from corroding the above two layers. In contrast, the closest prior art (D1) concluded that sodium has a beneficial effect on the growth of the absorbent layer and should not be prevented from entering the absorbent layer, without any concern regarding whether the sodium would damage the molybdenum-based electrode layer. D1 thus provides technical advice contrary to Claim 1. In light of this, if no creative work is done, a person skilled in the art will follow this technical teaching and add rather than reduce sodium, as suggested in Claim 1. It could be argued that to come up with the technical concept of the patent at issue, creative labour would be required. In such case, regardless of whether D2 discloses the material of the barrier layer or otherwise, the contrary teaching of D1 already demonstrates that Claim 1 does involve an inventive step.
In respect of the plaintiff’s view on whether the three-step method will be adopted to judge the patent’s inventive step, the court clearly highlighted that although the three-step method conforms with the objective characteristics of an invention, it is not the only way to examine inventive step. The assessment of the inventive step of an invention is to determine whether it is obvious to a person skilled in the art to achieve the invention of the patent at issue based on the prior arts. If it can be concluded that an invention is not obvious to those skilled in the art without accessing the three-step method, then that method is not essential in that instance.
The Beijing Intellectual Property Court did not provide a list of circumstances under which the three-step method failed to be applied in this case. However, according to the court, it is where the closest prior art provides an opposite technical teaching regarding the invention of the patent at issue.
The guidelines provide an alternative circumstance where the three-step method may not be applied “if the invention produces an unexpected technical effect, it means the invention represents notable progress on the one hand, and it also means that the technical solution of the invention is non-obvious and thus has prominent substantive features on the other hand. Therefore, the invention involves an inventive step… the examiner shall take the corresponding factors into account and avoid making a rash determination that the invention does not involve an inventive step”.
This view was reflected in a Beijing Higher People’s Court judgment at the second instance of invention patent invalidation proceedings. In this case, the appellant was the patentee of Invention Patent 200780016464.X (stainless steel with excellent corrosion resistance; ferritic stainless steel with excellent resistance to crevice corrosion and formability; and ferritic stainless steel with excellent resistance to crevices), who refused to accept Decision 18653 of the Patent Re-examination Board’s invalidation procedure and the Beijing First Intermediate People’s Court (first-instance court) judgment. Claim 7 sought to protect a ferritic stainless steel and its differences against the closest reference document:
- the weight percentage of manganese and titanium in the claim is between 0.05% and 1% and between 0.02% and 0.5% respectively; and
- the weight percentage of manganese and titanium in the reference document is 0.01% and 2% and between 0.01% and 1% respectively.
According to the board, more than one embodiment in the reference document selected the weight percentage of manganese in the 0.05% to 1% range. Meanwhile, selecting the weight percentage of titanium in the 0.02% to 0.5% range is common practice in the technical field, meaning therefore that Claim 7 has no prominent substantive features. However, the appellant argued that the document was designed to achieve a steel with excellent strength at high temperatures, and the present patent is designed to achieve a steel with strong corrosion-resistance properties.
The court held that in determining the inventive step of an invention involving chemical mixtures or compositions, it is possible to use the three-step method to determine the inventive step when those skilled in the art can predict the effects of changing components and their content ratio. However, the court emphasised that when it is difficult for those skilled in the art to predict the effects, the three-step method should not be applied mechanically. Instead, it should be considered whether the technical solution achieves an unexpected technical effect for determining inventiveness. This judgment is in accordance with the guidelines.
In general, in determining an invention’s non-obviousness, it must be considered whether a person skilled in the art would have an incentive to make improvements based on the prior art and obtain the invention at the time that it was made. Although the three-step method complies with the objective characteristics of an invention and can be used on many different kinds of invention, it is not the only way to examine inventive step. Where opposite technical teaching is provided, those skilled in the art cannot usually expect that the idea disclosed in the invention can contribute to the prior art. Without the incentive to improve, obtaining such an invention is usually considered non-obvious, meaning that the three-step method is therefore not essential under such circumstances. Where an invention provides technical effects which cannot be obtained in advance through reasonable prediction or reasoning by those skilled in the art, it is not obvious for those skilled in the art to adopt the technical solution of such invention to solve the technical problem or the technical problem corresponding to such unexpected technical effects. In such case, it can be determined that the invention involves an inventive step without applying the three-step method.