T 2567/19 (Fingerprint micro-scanning/IDENTIX) 04-08-2022

The application

1. The application relates to a method and system for micro-scanning a rolled fingerprint (page 4, lines 19 to 25). An image sensor is (micro-)displaced in a sequence of positions using two actuators translating the sensor linearly in orthogonal directions. The transmission of the movement from the actuators to the sensor uses parallelogram structures avoiding rotations during translation (page 12, lines 3-12).

1.1 To increase the overall stiffness of the apparatus, and thereby increase the resonant frequency largely above the actuator driving frequencies (page 13, middle paragraph), a stiffening device is coupled to both actuators and the mounting point of the image sensor. This way the sensor stabilises quicker at the desired positions (see e.g. page 6, page 11). This configuration allows one-time calibration (paragraph bridging pages 12-13) and open-loop control (page 6 lines 5-10).

1.2 The sensor acquires four (or more, depending on the movement schema - see figure 2C) images at each position, and these images are combined to form an image of higher resolution than that of the sensor itself (e.g. 1000dpi instead of 500dpi - page 5 lines 5 to 17). The sensor takes one image every 20ms (page 3 middle paragraph).

Article 123(2) EPC

2. The Examining Division found (decision 2.1 to 2.6) that the amendment from "the first, second, third, and fourth images can be combined in a composite image" (as contained in original method claim 18) to combining the four images (as contained in present method claim 10) adds matter, it was not unambiguously clear in the original text whether the images were combined or not.

3. As the appellant pointed out, the original expression already provides basis for the amendment. Firstly, the Board considers that the formulation that the images "can be" combined also discloses that these images "are" combined. Moreover, it is also inherent to the micro-scanning technique in general - and hence also to the specifically claimed application to fingerprinting - that images are combined to increase the effective sensor resolution, as is also disclosed in the current application at page 5, lines 5-6. Thus the Board disagrees with the Examining Division regarding this objection.

Article 83 EPC and Article 57 EPC

4. The Examining Division was of the opinion that the invention was insufficiently disclosed (points 3 to 5) and, therefore, not industrially applicable (point 6).

5. The first invoked reason (point 3) is that the micro displacements of the finger skin caused by the blood flow prevent accurate micro-scanning, because the requirement of immobility is not fulfilled. Further­more, according to the computations of the Examining Division, the time necessary to micro-scan a finger­print image pixel by pixel would be of 56 minutes, in which time the user will move its finger, and in which time anyway micro motion due to blood flow will occur.

6. The appellant argues (grounds of appeal, pages 4 to 7) that the Examining Division has misunderstood the functioning of the sensor. The image is not scanned pixel by pixel, but the whole sensor is moved. Each image acquisition takes 20 ms (at 50 Hz, for which technology was available). The time-scale needed to acquire an image is therefore much shorter than the one in which blood flow causes skin motions to occur (1 or 0.2 Hz).

7. The Board agrees with the appellant. The application makes clear that the image sensor is a CCD device acqui­ring a full image (see page 5 as cited above). Moving a 500 dpi sensor in four positions as in figure 2C results in an image of 1000 dpi. The time necessary to acquire a composite image is then only 80 ms (thus a sampling rate of 12.5 Hz), sufficiently short so that the resulting image is not influenced by micro motions of the finger.

8. Similar considerations apply to the reasons invoked by the Examining Division in section 4, wherein it is argued that natural tremor would prevent focusing (for touchless devices) or that pressure on the device (for touch devices) would modify the mechanical properties of the system and influence the micro displacements, which cannot be considered reliable. The Board has no reason to doubt the appellant's submission (grounds of appeal, pages 8 to 10) that the mentioned sampling frequency is significantly higher than that of the mentioned influences which, hence, do not negatively affect the imaging accuracy.

9. The Examining Division also considered (5.1 to 5.7) that the application lacked any details specific to fingerprinting techniques. As micro-scanning specifi­cally fingerprints was not commonly known, the missing aspects could not be filled by way of common knowledge.

10. The appellant submits (grounds of appeal, page 11) that it is not necessary for the application to provide ancillary details or basic information regarding finger­print imaging.

11. The Board agrees with the appellant that the applica­tion did not have to provide details, which, at the filing date of the application belonged to the common general knowledge of the skilled person. The proposed micro-scanning system can be used to replace the standard camera within any standard optical fingerprint sensor. The Board does not see any difficulties for the skilled person to do this, and so no further details are necessary here.

12. Finally, the Examining Division is of the opinion (5.8) that the application does not disclose the "formula and parameters required for achieving this necessary accu­rate determination of these relative positions", i.e. of the micro-scanning positions.

13. The Board agrees with the appellant (grounds of appeal, page 12) that this determination is disclosed by the mechanical configuration of the sensor. As the appli­cation explains, the control of the sensor posi­tio­ning is performed in an open loop relying on the accuracy of the actuators, on the calibration, and on the mechani­cal stability due inter alia to the dampe­ning of reso­nant behavior through the stiffening device.

Article 84 EPC

14. The Examining Division objected (point 7.1) to a (con­si­derable) number of functional formulations in the claims as being unclear. However, it did not specify what the lack of clarity was.

14.1 It stated that the functional features could not be implemented by way of common knowledge, or without undue burden (see 7.1.2.1, 7.1.5.1, 7.1.7.1, 7.1.9.1, 7.1.11.1, 7.1.12.1). The Board notes that this is an objection under lack of support - or lack of disclosure - objection, not a lack of clarity.

14.2 As the Examining Division remained generic in its objections, the Board cannot but see them as being substantially identical to the previous objections of a lack of disclosure, which were discussed above.

14.3 Regarding the clarity of the functional forms alone, the Board is of the following opinion: the features in contention mostly define mechanical parts (geometry, actuators, stiffening device, parallelogram structures) with functions clear to the pertinent skilled person, who must also be versed in mechanics. The parallelogram structures, which were extensively discussed during examination, are self-explanatory from figure 1 of the application. The function of the stiffening device and its influence on the resonant frequency is clear from the structural constraints claimed (its mechanical couplings). The positioning of the sensor for micro-scanning and the obtention of the 1000 dpi resolution is obtained by the open-loop control as discussed above. Thus the Board disagrees with the objections of the Examining Division.

15. The Examining Division also objected (point 7.2) to the use of the term "substantially" as being unclear, but did not explain what the ambiguity was. The mere use of the term does not render a claim unclear. Here, the term indicates tolerances that are well understood by the skilled person given their use context (positioning along two orthogonal axes), as the appellant also submitted (grounds of appeal page 21).

Conclusion

16. The Board thus comes to the conclusion that the objections raised in the decision under Articles 57, 83, 84 and 123(2) EPC are incorrect and so do not carry the refusal of the application. The decision must therefore be set aside.

16.1 However, the Examining Division has not carried out any examination as to patentability under Article 52 EPC for novelty or inventive step. It appears to the Board that the search itself did not cite prior art relevant in this respect, but merely documents of category "T", relevant only for the matter of (in)sufficient disclo­sure under Article 83 EPC, so an additional search may be necessary.

16.2 The Board considers these circumstances to constitute special reasons justifying the remittal of the case for further prosecution (Article 11 RPBA 2020, Article 111(1) EPC).