EP 3 725 436 A1 relates to electron beam melting machines that maintain target energy absorption during a print process.
Brief outline of the procedure
The ED refused the application for lack of sufficiency.
After amendment, restoring sufficiency, the board remitted for further processing.
The applicants’ point of view
The concept of the invention was based on the finding that the influence of the surface chemistry of the powder is reflected in the secondary electron emissions. This concept was so simple for a skilled person to put into practice that a specific illustrative working example was not required.
The disclosure in D1 was not relevant to the invention as defined in claim 1, since it related to different circumstances.
The ED’s decision
The ED based its finding on the disclosure of common general knowledge in paragraphs [0011] and [0094] of D1=WO 2018/217646.
In paragraph [0011], D1 refers to textbooks when stating that the yields of secondary electrons (SE) and backscattered electrons (BSE) “may be sensitive to the topographical characteristics of the specimen surface but have been found to be almost independent of the specimen temperature for metals, and thus the influence of the Heat Affected Zone (HAZ) of the in-process specimen on the electron signal is minimal”
For the ED it was not possible to determine electron emissions during an EBM method by measuring the temperature of the powder bed and the melt pool using a thermal imaging device as defined in what was then claim 3 of the MR, which corresponded to claim 6 as originally filed and was also disclosed in paragraph [0033] of the application as published.
The ED further observed that the application did not include a concrete experimental implementation of the claimed control method and that the applicants had not filed any such experimental evidence during the examination proceedings.
The board’s decision
The objection raised by the ED does not apply to the invention as defined by AR3, because claim 1 is now restricted to the determination of electron emissions by measuring transmitted electrons, secondary electrons and backscattered electrons. Therefore, the invention no longer encompasses thermal imaging for the measurement of electron emissions.
Regarding the remaining methods of determining electron emissions, it is undisputed that the skilled person knows how to measure transmitted electrons directly by determining the electric current passing through the build platform of the additive manufacturing machine as defined in claim 1.
Furthermore, the skilled person knows that secondary and backscattered electron emissions can be measured using, for example, an Everhart Thornley detector, cf. paragraphs [0031], [0032] and [0041] of the application.
The previous objection of lack of sufficient disclosure thus no longer applies, and the board saw no reason hindering the skilled person in carrying out the invention as defined by claim 1 of AR3.
For the board, the further objections of lack of sufficient disclosure raised by the ED were not convincing.
The ED argued that the claimed invention ignored the reality of physics of the radiation phenomena around the melt pool, particularly thermal conduction, topography and emissions, heat and X-ray, and falsely assumed that the electron emissions at least mainly depended on the absorbed energy.
Under these circumstances, it was also impossible to accurately measure the absorbed energy, and it was impossible to achieve the desired effect, namely to maintain the absorbed energy at a target level using the disclosed method.
The board held that this line of reasoning does not take into account the fact that the claimed method does not require accurate measurement of the absorbed energy.
The invention defined in the application is based on the assumption that the absorbed energy can be determined simply by calculating the amount of the absorbed electrons, irrespective of whether or to what extent thermal conduction, heat emission or X-ray radiation occurs as a consequence of the high-energy beam of electrons hitting the metal target powder, i.e. without knowing the “true” level of emissions.
Claim 1 only requires the incident energy level to be adjusted to compensate for the measured electron emissions, and thus the absorbed energy to be maintained at a target level.
The Board saw no difficulty for a skilled person using their CGK to apply the application’s teaching to improve the manufacturing method by providing a stable method as aimed at in paragraph [0005] of the application.
The aim of the claimed invention is to provide a control action in the absence of knowledge of the surface topology and chemistry, because these are subject to unpredictable variations that are to be compensated for by the claimed method.
This is achieved by determining the electron emissions and calculating the absorbed energy by subtracting the measured electron emissions from the incident energy level.
When carrying out the invention, it is not necessary to determine the surface chemistry of the metal powder or to establish specific correlations between the surface chemistry and the absorbed energy or between the electron emissions and the melt pool temperature.
However, in the case at hand, a concrete working example is not required in view of the above conclusions relating to compliance with the requirements of Art 83.
According to established case law, see CLBA, 11th edition, 2025, II.C.5.3, a clear distinction must be made between the concepts of “way of carrying out the invention claimed” and “examples” as referred to in R 42(1,e).
While the description as a whole must disclose, in the light of the CGK at the priority date, at least one way of carrying out the invention, examples are not always necessary to satisfy the requirement of sufficiency of disclosure. The presence of examples is only indispensable if the description is otherwise insufficient to meet this requirement.
In the present case, methods for determining the transmitted, secondary and backscattered electrons are described sufficiently clearly and completely, as ways of carrying out the invention.
The board added that, in the present case, the skilled person does not require a detailed experimental embodiment of the invention to implement the invention as defined in claim 1.
Comments
The present decision illustrates the problem of asserting a lack of sufficiency during examination. On paper every machine works, unless its underlying principle runs clearly against normal laws of physics, e.g. in case of a perpetuum mobile.
The present decision is interesting as sufficiency was not decided with respect to a piece of prior art, which is not possible, but with respect of CGK disclosed in a oiece of prior art.
In the present case, a proper example would certainly have helped sufficiency.
I am not specialist in the matter, but the absence of an example makes me reasonably suspicious. It was sufficient to delete from the claim aspects which manifestly could not be reproduced on the basis for the disclosure, to fulfil the requirement of sufficiency. A bit thin.
Whether the invention is sufficiently disclosed will only be clarified should an opposition be filed or the proprietor claims infringement and the alleged infringer files a counterclaim for nullity.
If not, the present application, should it come to grant, might end up in the Bermuda triangle of patents having never reached the marketplace.
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