T 1301/17 (Dryer / Goji) of 8.2.2022

European Case Law Identifier: ECLI:EP:BA:2022:T130117.20220208
Date of decision: 08 February 2022
Case number: T 1301/17
Application number: 08710231.5
IPC class: H05B 6/80
D06F 58/26
Language of proceedings: EN
Distribution: D
Download and more information:
Decision text in EN (PDF, 430 KB)
Documentation of the appeal procedure can be found in the Register
Bibliographic information is available in: EN
Versions: Unpublished
Applicant name: Goji Limited
Opponent name: BSH Hausgeräte GmbH
Board: 3.4.01
Headnote: -
Relevant legal provisions:
European Patent Convention Art 56
European Patent Convention Art 100(a)
European Patent Convention Art 100(b)
European Patent Convention Art 100(c)
European Patent Convention R 99(1)(c)
Keywords: Admissibility of appeal - (yes)
Sufficiency of disclosure - (yes)
Amendments - added subject-matter (no)
Inventive step - (yes)


Cited decisions:
T 0009/08
T 2561/11
Citing decisions:

Summary of Facts and Submissions

I. The opposition against European patent 2 127 482 was based on Articles 100(a), (b), and (c) EPC.

II. The Opposition Division rejected the opposition, thereby maintaining the patent as granted.

III. The opponent appealed, requesting that the decision be set aside and the patent revoked. The argumentation was based on the following documents:

D1: US 5,521,360 A

D2: WO 95/27387 A1

D3: DE 20 2006 018 276 U1

D4: DE 10 2004 016 725 A1

D5: WO 01/46509 A1

D6: EP 1 321 566 A1

D7: EP 1 321 564 A1

D8: GB 2 217 824 A

D9: US 4,415,789 A

D11: EP 1 321 565 A1

IV. The proprietor responded by requesting the rejection of the appeal because it was not admissible and because none of the reasons for opposition was pertinent.

V. With a letter filed more than three years after notification of the grounds of appeal, the proprietor stated that they maintained "all submissions and Auxiliary Requests made at first instance before the Opposition Division", and that, should the Board be "minded to overturn the decision" on the main request, the case should be remitted to the first instance for consideration of the ten auxiliary requests. In the further alternative, the auxiliary requests should be considered by the Board.

VI. The Board informed the parties of its preliminary opinion, according to which

(a) the appeal was admissible;

(b) the invention according to the main request was sufficiently disclosed;

(c) the subject-matter of the main request did not extend beyond the content of the application as filed;

(d) the subject-matter of claims 1 and 9 of the main request was novel,

(e) but did not involve an inventive step;

(f) the admission of the ten auxiliary requests fell under Article 13(1) RPBA 2020.

VII. The Board conducted oral proceedings during which the admission and allowability of the above requests was discussed.

VIII. Claims 1 and 9 of the main request read (without reference signs):

1. A dryer, comprising:

a cavity adapted to receive at least one object to dry;

at least one broadband RF source configured to radiate RF energy into the cavity; and

a controller for controlling the RF source to dry the object;

characterized by a spectral imaging module for providing a spectral image of items in the dryer, and in that the controller is configured to adjust the RF energy in response to the spectral image.

9. A method of drying an object in a cavity using RF energy radiation, the method comprising:

radiating RF energy into the cavity using a broadband RF source;

characterized by:

obtaining a spectral image of items in the cavity; and

adjusting RF energy in response to the spectral image.

IX. The claims of the auxiliary requests are not relevant for the decision.

X. The opponent's arguments that are relevant for the present decision can be summarized as follows:

(a) Admission

The opponent was adversely affected by the Opposition Division's decision, because their request to revoke the patent in its entirety was not granted. The appeal was a request to alleviate this adverse effect, which implied a request to revoke the patent. Hence, the notice of appeal contained an implicit statement of the subject of appeal and the appeal was, therefore, admissible even without an explicit statement.

(b) Sufficiency of disclosure

Claims 1 and 9 distinguished between at least one "object to dry" and "items in the dryer" without defining their relation. It was not apparent, whether the same single entity or the same plural entities were meant, or whether the expressions referred to different entities. It was also not apparent, how the optional passive source 2080 related to those expressions. The description was no help when it came to carrying out the invention, because it was a mere collection of optional features and unrelated subject-matter.

It was also not possible to carry out the control of the "air heating" defined in claims 5, 6, 12, and 13. Nowhere did the patent explain what was meant by the air heater and how it was to be combined with the invention.

(c) Added subject-matter

Claims 1 and 9 were amended with respect to claim 41 as originally filed, the amendments including the deletion of a memory and the addition of a particular controller. The resulting dryer and method of drying, however, were not originally disclosed. A mosaic of unrelated features from the description, in particular from passages that had been deleted during examination proceedings, was not allowed.

According to claim 2, the heating policy was adjusted in terms of one or more transmitted frequencies, whereas the original application did not disclose an adjustment during drying but only a selection. In addition, this was a selection of frequency bands, not of single frequencies.

Claims 7 and 14 defined an adjustment of matching powers for matching times. This was not disclosed in relation with the embodiment of Figure 20.

Also claims 6 and 8 did not have a basis in the application as filed, even less in combination with the subject-matter of claim 1.

(d) Novelty

D1 comprised all features of claims 1 and 9. In particular, an application of the material processing apparatus as a dryer was implicit and followed from its suitability for heat treatment and from its application to materials that underwent phase transitions. The same held for D2. Also, D8 disclosed all features of claims 1 and 9, considering that an image that was acquired over a certain spectral range was a spectral image.

(e) Inventive step

If the term spectral image was interpreted more narrowly, D8 disclosed all features of claims 1 and 9 except the provision of a spectral image and the adjustment of the RF energy in response to it. This difference had no technical effect. However, even if a technical effect were acknowledged, the skilled person would have solved the corresponding technical problem of providing an improved moisture measurement, or of refining the outdated dryer of D8, by combining D8 with the spectral imager described in any of D3, D4, D5, D6, D7 or D11. D9 was mentioned but was not used for an argument.

XI. The proprietor's arguments that are relevant for the decision are reflected in the reasons, below.

Reasons for the Decision

Admissibility of the appeal

1. According to the proprietor, the wording "Hiermit wird [...] Beschwerde gegen die Entscheidung vom 21 March 2017 eingelegt", in the notice of appeal, could not be considered "a request defining the subject of appeal" within the meaning of Rule 99(1)(c) EPC, considering that this statement did not establish the extent of the appeal.

2. The decision under appeal was the rejection of the opposition. According to established jurisprudence (Case Law, 9th Edition, V.A.2.5.2 c)), an appeal against that decision must be interpreted as a request that the Board set aside this decision and revoke the patent.

3. The presence of requests that were ranked lower than that on which the maintenance was based does not matter (T 2561/11, item 2.5; T 9/08, item 1).

4. In consequence, the requirements of Rule 99(1)(c) EPC are fulfilled, and the appeal is admissible.

Main Request - Sufficiency of disclosure

5. The patent describes a dryer, especially one for drying clothes. The general set-up is described under the heading "Exemplary modified RF oven" with reference to Figures 20, 33, and 34 (see paragraphs [0242] - [0291]). The reader understands that the "exemplary embodiments", which are mentioned in this section, do not refer to unrelated or mutually exclusive dryers, as alleged by the opponent. Rather, they describe various aspects of the same general dryer 2000 that is illustrated by Figure 20, many of which can be combined.

6. In the dryer according to the invention as claimed, RF energy is radiated into a cavity of the dryer ([0243] - [0245]) and its energy level is adjusted based on a spectral image of the items in the dryer. The RF resonance-modes in the cavity depend on the dielectric constant of the contents of the drum, and, therefore, on the moisture content of the items in the dryer (see paragraphs [0248] and [0256]), irrespective of how many items there are.

7. The spectral image will be influenced by the geometry, the components and the contents of the cavity. As the opponent pointed out, the cavity may contain passive sources that convert absorbed RF energy to heat (paragraph [254]). Although such passive sources might change the appearance of the spectral image, the skilled person understands that neither are they "objects to dry" in the sense of the claims, nor do they contribute to the differences that are used for the adjustment of the RF energy and that are occurring in the spectral image during the drying process ([0248], [0256] and [0273] - [0277], together with Figures 33a - 33d).

8. With that understanding, the skilled person has no problem in carrying out the invention as defined in the claims, by inserting one or more "objects to dry", for example items of clothing, into the drum inside the cavity in order for them to be dried.

9. The patent describes conventional dryers as using heated forced air for drying (see [0315]), in contrast to the RF heating used by the invention. In variations of the invention, the RF heating is combined with such conventional forced air heating in a hybrid system (see [0315] - [0324] and Figures 22 - 24; also [0234] - [0241]). It lies within the knowledge of the skilled person to combine the control of the RF heater, which is described in relation to Figure 20, with a conventional, well-known control of a forced air heater, in order to realize a common controller as referred to in paragraph [0264].

10. It follows from the above that the skilled person is able to carry out the invention as defined in claims 1 and 9 and in claims 5, 6, 12, and 13. Hence, the ground for opposition under Article 100(b) EPC does not prejudice the maintenance of the patent.

Main Request - Added subject-matter

11. Claim 1 defines a dryer that uses broadband RF radiation for drying an object in a cavity. The RF energy is adjusted in response to a spectral image of items in the dryer. Claim 9 defines a corresponding method of drying.

12. In the application as filed, the general set-up of a dryer using RF energy for drying is described with reference to Figures 20, 33, and 34 in the section headed "Exemplary modified RF oven" on page 107, line 11, to page 117, line 15. As mentioned under point 5. above, and in contrast to the opponent's view, the skilled person understands that the various "exemplary embodiments" referred to in this and the following sections describe different aspects of the dryer of Figure 20 that can be combined with each other, wherever it makes technical sense.

13. There is no hint, in this or other parts of the description, of any features that are essential for the invention, but which are not defined in claims 1 and 9. In particular, the application does not imply that a memory storing a desired temperature schedule or an energy deposition profile are essential for adjusting the RF energy based on a spectral image, because these are separate aspects.

14. Hence, there is a basis for the application as filed for the subject-matter of claims 1 and 9.

15. The RF dryer of Figure 20 comprises a cavity and a broadband RF source controlled by a controller. In the aspect that relates to the invention as claimed, the dryer comprises a spectral imaging unit that acquires spectral images of the RF power in the cavity (as illustrated by Figures 33a - 33d). The controller uses these images as an input for a feedback control, which adjusts a heating policy by changing the RF energy (page 110, line 24 - page 111, line 14). The adjustment may be made in terms of the transmitted frequencies (page 110, lines 28 - 31), as is defined in claim 2 and in the first of two alternatives in claims 7 and 14. Alternatively, the adjustment may be performed in terms of an accurate delivery of desired amounts of energy at relevant times (paragraph bridging pages 110 and 111), as is defined in the second of the two alternatives in claims 7 and 14.

16. The passage of the application as filed on page 9, lines 11 - 23, is part of the general description of the invention. It describes the embodiment, in which the dryer uses a spectral image to adjust the RF energy in the cavity in terms of frequencies or power. Hence, it must refer to the same embodiment as described in further detail with reference to Figure 20 (see previous point). The passage on page 9 uses the same wording as claims 2, 7, and 14, namely an adjustment in terms of "one or more transmitted frequencies" or "matching powers for matching times".

17. Hence, there is also a basis in the description as filed for an adjustment of frequencies or of power, as defined in claims 2, 7, and 14.

18. In a particular case of adjusting the frequencies, the controller allocates the RF energy to different RF frequency bands (page 111, lines 4 - 6), as is defined in claim 8. Such an adjustment of frequency bands is further described in relation to the methods of operation of the dryer under the heading "Exemplary Methods of drying clothing" (page 123, line 17 - page 125, line 19; Figures 28 and 29). These methods are compatible with the dryer according to Figure 20 (see page 123, lines 18 - 21) and describe embodiments in which the controller either selects or reduces the energy in certain frequency bands (see page 124, lines 5 - 7 and page 124, line 31 - page 125, line 2).

19. Hence, there is also a basis in the application as filed for a controller that is configured to vary the intensity of at least one frequency band, as defined by claim 8.

20. In an "embodiment of the invention" that refers to the RF dryer 2000 of Figure 20, the RF power can be controlled to follow a certain predetermined drying profile (page 113, lines 3 - 9) in order to ensure minimum energy consumption (page 113, lines 23 - 26), fastest drying duration (page 114, line 7) or reduced damage to the clothing (page 117, lines 7 - 12), wherein the damage may be caused by high agitation (page 114, lines 17 - 20). It follows from the context that the control can be based on the measurement of humidity by the spectral imaging module (see for example page 109, line 31 - page 110, line 2 and page 110, lines 28 - 31). The reader understands that the features of this RF dryer can be "incorporated into an open system or a closed system forced air dryer" (see the introductory section "Use of RF energy to dry a target", starting on page 105; in particular page 106, lines 15 - 17) and are, therefore, compatible with the hybrid dryers described in relation to Figures 22 - 24, which combine RF heating with conventional force air heating.

21. The corresponding general section on page 5, line 28, to page 6, line 20, further elaborates on the drying profile in so far as the spectral imaging can be used to measure humidity for controlling the drying process in accordance with a desired drying profile, which can comprise a final dryness or a drying time limit. Moreover, page 7, lines 22 - 30 describe that that fixed (maximum) agitation rates may be used to limit damage. This means that a maximum agitation rate is part of a drying profile (see also page 50, lines 27 - 28, which is also directed at RF drying of objects in the cavity of a forced air dryer).

22. Hence, there is a valid basis for the subject-matter for claim 6 in combination with claims 1 and 5.

23. The general section "Summary of the invention" on pages 4 - 51 was almost completely deleted during examination proceedings. The opponent argues that the amendments may not be based on passages of the description that were not part of the patent specification.

24. This argument is not persuasive. It is the application as filed and not the application as amended during examination proceedings that is referred to in Article 100(c) EPC. Only subject-matter that has been abandoned cannot be re-introduced into the claims. However, this is not the case here. The deletion did not happen prior to the amendments but was submitted at the same time, with the letter of 28 November 2012. Further, the deletion was not an abandonment of subject-matter but a reaction to the Examining Division's request to adapt the description to the claims. Regardless of this, the description relating to Figure 20 already constitutes a sufficient basis for the amended claims, as has been shown above.

25. For these reasons the ground for opposition under Article 100(c) EPC does not prejudice the maintenance of the patent.

Main Request - Novelty and Inventive Step in view of D1 and D2

26. Document D1 is directed to a microwave furnace for material processing. It describes, in its section about background art, microwave ovens for preparing food or for drying, using a single frequency at 2.45 GHz that is particularly matched for the heating of water. It goes on to describe that such ovens were not well suited to material processing or treatments like sintering or sterilization, because different materials required different - and sometimes changing - frequencies. The purpose of the invention in D1 was to provide a microwave furnace that was able to adjust the microwave frequency to the particular material, or to the particular processing or treatment application, where the material to be heated was not exclusively water (see the end of the background art section and the beginning of the sections describing the disclosure of the invention and the best mode for carrying out the invention). Hence, D1 is explicitly not directed to a dryer, which, according to D1, would require only the frequency of 2.45 GHz.

27. According to the opponent, the microwave heating apparatus of D1 did not exclude drying as one of its applications. D1 even mentioned, explicitly, an application on materials that underwent phase transitions. One such material was water. Hence, drying was one of the applications of the apparatus in D1. Further, the claims of the application in suit did not exclude applications other than drying, and, therefore, D1 disclosed a dryer in the sense of the claims.

28. This argument is not persuasive. D1 provides a "microwave-based materials processing system" with a "furnace cavity". Drying is not amongst the listed, exemplary applications of material processing (see column 3, lines 14 - 41). Although this list is not exhaustive, the types of application mentioned, together with the explicit contrast of the invention to "microwave ovens" used for heating water, for example for drying (see column 1, lines 36 - 47), makes it clear that the described microwave furnace for material processing is not a "dryer". As to the phase transitions mentioned by the opponent, D1 aims at selecting different microwave frequencies in such a way that each phase of a material undergoing a phase transition couples efficiently to at least one of the frequencies used (column 7, lines 24 - 34). In a dryer, there is no need to couple the microwave radiation to vaporized water in its steam phase.

29. It follows that the furnace in D1 cannot be interpreted as a dryer in the sense of a device that is particularly designed to evaporate water from moist objects, and that the Examining Division did not err in finding that the subject-matters of claims 1 and 9 were novel over D1 (Article 54 EPC).

30. It also follows that the skilled person would have been led away from using the furnace of D1 as a dryer, and that D1 is not a promising starting point for an inventive-step objection (Article 56 EPC).

31. The same holds for the very similar document D2.

Main Request - Novelty over D8

32. Document D8 discloses a dryer for drying clothes (page 1, first and second paragraph). It comprises a microwave emitter that radiates microwave energy into a resonant, plane-parallel cavity, which includes a portion of the dryer's drum (D8, paragraph bridging pages 3 and 4, and Figure 1). A microwave sensor detects the intensity of the radiation in the cavity. The sensor signal is used as input for a feedback loop, in which a controller adjusts the power of the emitter, such that the level of radiation in the cavity is maintained constant. During the drying process, the moisture content in the clothing, and the energy it absorbs, decreases. This allows a reduction in the power emitted into the cavity (page 4, last paragraph).

33. According to the opponent, page 4, lines 4 - 6 of D8 disclosed a broadband source that emitted in the wavelength range from 10**(-2)m to 10**(-1)m. This whole spectrum of radiation was detected by the microwave sensor, which, therefore, acquired a "spectral image" of the radiation. This was because it contained the cumulated intensity information over the whole spectrum of the radiation. Unlike a spectrum, a "spectral image" did not require spectrally-resolved information, and claim 1 of the patent in suit did not define the unusual expression "spectral image" any more precisely. The sensor signal or spectral image was used to adjust the emitted power. Hence, D8 disclosed all features of claim 1.

34. This understanding of D8 is not persuasive.

35. The second complete paragraph on page 4 of D8 describes that the cavity between reflectors 62 and 64 is designed for resonance of one wavelength lambda. Hence, the source is emitting radiation that cannot differ from lambda by more than a fraction of the wavelength, or else the resonance condition would no longer be met. Therefore, lines 4 - 6 of page 4 must be understood such that the one emitted wavelength lambda lies within the range from 10**(-2)m to 10**(-1)m.

36. Whether the radiation at wavelength lambda can nevertheless be interpreted as "broadband" is not relevant for the decision and is left unanswered.

37. The signal generated by the microwave sensor 66 is integrated over all frequencies within the measuring range of the sensor. The resulting signal is devoid of spectral or frequency-dependent information. However, this would be required even by a broad interpretation of the term "spectral image".

38. Hence, D8 does not disclose a "spectral imaging module" that would allow the derivation of frequency-dependent information, and it does not disclose an adjustment of RF energy in response thereto.

39. Therefore, the subject matter of claim 1 is new over D8 (Article 54 EPC). The same applies to the subject-matter of claim 9.

Main Request - Inventive Step - D8 combined with D6, D7, or D11

40. The subject-matter of claim 1 differs from D8 in that the dryer comprises "a spectral imaging module for providing a spectral image of items in the dryer", and in that "the controller is configured to adjust RF energy in response to the spectral image".

41. In order to assess the technical effect of the difference, the meaning of the distinguishing features needs to be clarified.

42. The opponent is right in stating that claim 1 does not define the way in which the spectral image is used for the adjustment of the RF energy. Consequently, the claim covers embodiments in which the adjustment does not make use of spectrally resolved information contained in the spectral image. For example, if only the integrated power over all frequencies is used for an adjustment of the energy to a desired level, this would fall within what claim 1 defines.

43. However, this does not mean that the opponent is correct in saying that the difference had no technical effect at all. The presence of the spectral image still allows the use of the spectral information contained therein, not only for an adjustment of RF energy, but also, for example, for determining the presence of metal objects, or for determining moisture, temperature or other quantities of interest. Thus providing this information constitutes a technical effect.

44. The opponent argues that the objective technical problem, assuming there was one, was to improve moisture measurement, because moisture was the main factor that influenced the spectral image defined in claim 1. The skilled person would have considered that problem when starting from D8, because moisture was measured in D8 and was directly correlated with the control signal.

45. This is not persuasive. First, because claim 1 does not define a relation between the spectral imaging and a moisture measurement, not even implicitly. As mentioned above, a spectral measurement allows the retrieval of several different kinds of information. Second, an analysis of the distinguishing feature from the perspective of D8 does not involve moisture. In D8, moisture in the cavity is not measured and knowledge of the moisture content would serve no purpose. Of interest is only the radiation level in the cavity, which is to be controlled to remain constant during the drying process. It is sufficient to know that moisture is correlated with the amount of absorbed radiation, as is acknowledged in the last paragraph of page 4 of D8. More precisely, it is the power level of the microwave emitter that is necessary to keep the radiation level constant, that correlates with moisture. However, an actual measurement of the moisture is not performed and would require proper calibration or a complicated calculation, or both. As no moisture measurement is disclosed in D8, the skilled person would not consider the problem of improving such measurement upon the basis of the disclosure of D8.

46. The opponent also offers the problem of improving the dryer of D8. However, this problem is too unspecific in view of the distinguishing features. Rather, the objective technical problem lies in providing more information about the drying process.

47. The opponent argues that the skilled person, starting from D8, would have been motivated to look for a way to provide more information on the moisture content of the clothes in the cavity, because this allowed a better understanding and control of the drying process. This would have been particularly helpful towards the end of the drying process, when the system losses in RF energy masked the contribution of the moisture on the measured RF signal. It was for that reason that D8 relied on the measurement of moisture sensor 40 for stopping the drying process. The skilled person would have found a better moisture determination in D6, based on the measurement of several frequencies. Using the spectral moisture measurement of D6 would have made the additional moisture sensor 40 in D8 superfluous. The combination of D8 with the spectral imaging of D6 would have led to a dryer as defined in claim 1.

48. In contrast to the opponent's argumentation, it is questionable, whether the skilled person would have considered the problem at all, because D8 already provides sufficient information through a "door closed sensor" 29, a moisture sensor 40 in the duct, a microwave sensor 66, and a timer circuit 70. More information is not needed for the drying process in D8. However, even if the skilled person would have considered a provision of more information, she would most probably have thought of employing more sensors, for example a temperature sensor or a filling state sensor.

49. As explained under the section concerning novelty, above, the moisture in the cavity was not of interest in D8. However, even if it had been, the skilled person would either have placed an additional moisture sensor in the cavity or have used the correlation between the controlled power level of the microwave emitter and the moisture content to calculate the moisture. This would not have led to spectral imaging. There is no motivation to look for an exact moisture measurement, much less a complicated one including spectral imaging, because there is no control in D8 that would benefit from such exact moisture measurement. Hence, the skilled person would not have considered document D6, or the very similar document D7, both of which are directed to exact moisture measurement (respective paragraphs [0008] of D6 and D7) using a broadband source and a spectral measurement with a complicated signal processing (paragraphs [0030] - [0033] of D6 and [0027] of D7). In addition, the presence of additional frequencies in D6 and D7 would lead to a higher overall energy consumption, which would be in contrast with the teaching of D8 (page 5, last paragraph).

50. It follows from the above that the subject-matter of claims 1 and 9 involves an inventive step over D8 in combination with D6 or D7 (Article 56 EPC). The same holds for a combination with D11, which is similar to D6 and D7.

Main Request - Inventive step - D8 combined with D3, D4 or D5

51. The Examining Division's finding that D3 was not prior art within the meaning of Article 54 (2) and (3) EPC is not disputed by the opponent. Hence, the opponent's arguments relating to D3 are not considered.

52. Documents D4 and D5 are less suitable for a combination with D8 than D6 or D7. For D4, the same arguments apply as for D6 and D7 and, in addition, the selective excitation of certain spatial resonance modes in the cavity of a dryer requires a positioning of the microwave emitter at the centre or half height of the cavity, which is not compatible with the positioning in D8 (see Figures 2 - 4 and paragraphs [0040] - [0042] of D4 and Figure 1 of D8). D5 uses light instead of RF radiation for measurement and thereby relies on a very different measurement technique.

53. It follows that the subject-matter of claims 1 and 9 also involves an inventive step over D8 in combination with D4 or D5 (Article 56 EPC).


54. The invention as described in the patent as granted is sufficiently disclosed for it to be carried out by a skilled person. The claims are clear, and their subject-matter is new and not obvious over the cited prior art documents.

55. Hence, none of the grounds for opposition under Article 100 EPC prejudices the maintenance of the patent as granted (main request).


For these reasons it is decided that:

The appeal is dismissed.

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