T 2069/17 - Different technical fields

Key points

• This examination appeal concerns the inventive step of the ‘method for imaging a biological sample’ of claim 1.
• D3 is the closest prior art and discloses a method for imaging a biological sample. “Document D3 fails to disclose the features relating to the corrective optics, i.e. that corrective optics are removably inserted between the detector and the flow cell [...] The technical effect of this difference is that spherical aberration is compensated for and the problem to be solved is therefore to improve image quality.”
• “Document D6 discloses a microscope for imaging different layers of a sample in a sandwich configuration. D6 further identifies a change in optical medium as the cause for aberration [...] and states that corrective optics are inserted to compensate spherical aberration due to a change in the optical medium [.] Therefore, corrective optics have been employed in document D6 for the same purpose as in claim 1. It would be obvious to the person skilled in the art, namely when the same result is to be achieved as in claim 1, to apply corrective optics with corresponding effect in the imaging method disclosed in document D3, thereby arriving at a method for imaging a biological sample according to claim 1.”
• “The appellant argued that D6 disclosed a specific type of microscope which recorded the track of cosmic rays. Thus, the technical fields of D6 and D3 differed significantly and the skilled person would not consult document D6 when starting from a sandwiched flow cell as disclosed in D3.”
• “The board is of the opinion that document D6 relates to optical microscopes in general (see title and column 1, lines 10 to 16: "Field of the Invention") and offers a solution (insertion of corrective optics) for the correction of spherical aberration that occurs due to imaging of layers at different levels (see claim 1,  [...]). Therefore, the skilled person would consider document D6 and apply its teachings in order to solve the objective technical problem.”
• D6 is US 4,563,062.
• As a comment, I think that this is a case which illustrates that the credibility of the EPO depends on how good the technical members of the Board can assume the role of the notional skilled person. I don't know whether a skilled person working in the field of D3 (link) would consult D6. I note that the Board does not expressly identify the skilled person. I would say it is the skilled person working with the technology of D3. D3 is a patent application carefully drafted to not overly restrict the scope of application of the claimed device, though the focus of D3 appears to be DNA microarrays (‘Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome’; Wikipedia). So the skilled person would likely be an engineer involved in the design of microscopes for reading out such DNA microarrays. Perhaps this would be an optical engineer; perhaps it would be another kind of engineer. Similarly, D6 is a patent carefully stating the 'field of the invention' of the claimed optical system in the most general terms. In the very next paragraph, it acknowledges as prior art "an emulsion chamber is one of the known apparatus for recording the track of cosmic rays." At least prima facie, D6 does not seem to be the kind of handbook that illustrates basic principles of optical engineering in general. But perhaps an optical engineer would search broadly for any literature addressing the optical problem at issue, irrespective of the precise application (assuming that the skilled person of D3 is an optical engineer instead of a biologist). 

EPO T 2069/17 - link

Reasons for the Decision

1. Main request - Inventive Step - Article 56 EPC

1.1 Closest prior art

Document D3 represents the closest prior art and discloses a method for imaging a biological sample, where the biological sample comprises a flow cell (100) with a first biological sample (21) disposed on a first surface (20) and a second biological sample (11) disposed on a second surface (10) of the flow cell, such that the first and second surfaces face each other (see paragraphs [0024] to [0026] and figures 1 and 3). The biological samples are excited by a radiation source and radiation emitted from the two surfaces is detected (see paragraphs [0012] "Fluoreszenzmessungen" and [0036] "Fluoreszenzdetektion"). According to D3, the fluorescence measurements are performed at the flow cell through the first surface (see paragraphs [0035]), i.e. the flow cell is mounted as a whole on an imaging station such that the first surface (20) is disposed between the detector and the second surface (10). This is confirmed by the statement that the measuring time is reduced due to fluorescence measurements at the first and second surfaces (see paragraph [0012]).

1.2 Difference

Document D3 fails to disclose the features relating to the corrective optics, i.e. that corrective optics are removably inserted between the detector and the flow cell into an optical train comprising an objective and imaging optics (inserted either between an objective and the flow cell or between a detector and the objective) such that the corrective optics reduce spherical aberration of detection at the first surface.

1.3 Technical effect and problem to be solved

The technical effect of this difference is that spherical aberration is compensated for and the problem to be solved is therefore to improve image quality.

1.4 Combination with document D6

With respect to the disclosure of document D6 the board agrees with the line of argument provided by the examining division (see section 2.1.5 and 2.1.6 of the appealed decision) and is of the opinion that the solution proposed in claim 1 cannot be considered to involve an inventive step (Articles 52(1) and 56 EPC).

The fluid medium between the sandwiched biomolecule arrays disclosed in D3 necessarily provokes a change in spherical aberration when imaging the first or the second emissive component at the first or second surface of the flow cell and therefore a change in image quality. The skilled person would be motivated to compensate for the change in spherical aberration.

Document D6 discloses a microscope for imaging different layers of a sample in a sandwich configuration. D6 further identifies a change in optical medium as the cause for aberration (column 1, lines 42 to 55 and column 2, lines 60 to 63) and states that corrective optics are inserted to compensate spherical aberration due to a change in the optical medium (column 1, lines 10 to 15 and column 2, lines 60 to 63).

Therefore, corrective optics have been employed in document D6 for the same purpose as in claim 1. It would be obvious to the person skilled in the art, namely when the same result is to be achieved as in claim 1, to apply corrective optics with corresponding effect in the imaging method disclosed in document D3, thereby arriving at a method for imaging a biological sample according to claim 1.

The subject-matter of claim 1 therefore does not involve an inventive step (Articles 52(1) and 56 EPC).

1.5 Appellant's arguments

1.5.1 The appellant argued that D6 disclosed a specific type of microscope which recorded the track of cosmic rays. Thus, the technical fields of D6 and D3 differed significantly and the skilled person would not consult document D6 when starting from a sandwiched flow cell as disclosed in D3.

The board is of the opinion that document D6 relates to optical microscopes in general (see title and column 1, lines 10 to 16: "Field of the Invention") and offers a solution (insertion of corrective optics) for the correction of spherical aberration that occurs due to imaging of layers at different levels (see claim 1, column 1, lines 42 to 55 and column 2, line 60 to column 3, line 16). Therefore, the skilled person would consider document D6 and apply its teachings in order to solve the objective technical problem.

1.5.2 The appellant further argued that D6 did not disclose the claimed arrangement because in D6 the corrective optics were inserted between lenses 15 and 16 of the objective.

The board is not convinced by this argument because D6 discloses that the objective can comprise only a single lens and that the corrective optics can be inserted on the image side of this lens (see column 7, lines 53 to 61). This arrangement is identical to the second alternative in feature (d) of claim 1, where the corrective optics is inserted between the detector and the objective.

1.5.3 The appellant argued further that the arrangement disclosed in document D6 differed from the claimed arrangement in that the objective and the corrective optics were moved together (see column 4, lines 28 to 31).

The board is not persuaded by this argument because claim 1 only defines the geometrical arrangement of the corrective optics and the objective, but contains no restriction with regard to the mechanical connection of the two.

1.5.4 Finally, the appellant argued that the arrangement of document D6 was such that the corrective optics were inserted when the lower surface (2b) was observed (see column 4, lines 49 to 52), whereas the claim defined that the corrective optics were inserted when radiation from the upper (first) surface (18) was detected (see features (b) and (c)).

The board is of the opinion that the skilled person understands that the order in which the different layers are imaged is of no importance to the effect of correcting the aberration. Therefore the claimed order of imaging is an obvious alternative.