T 1740/15 () of 16.11.2017

European Case Law Identifier: ECLI:EP:BA:2017:T174015.20171116
Date of decision: 16 November 2017
Case number: T 1740/15
Application number: 05733798.2
IPC class: G02B 26/08
Language of proceedings: EN
Distribution: D
Download and more information:
Decision text in EN (PDF, 305.949K)
Documentation of the appeal procedure can be found in the Register
Bibliographic information is available in: EN
Versions: Unpublished
Title of application: SYSTEM AND METHOD FOR CANCELING DISTURBANCE IN MEMS DEVICES
Applicant name: Capella Photonics, Inc.
Opponent name: -
Board: 3.4.02
Headnote: -
Relevant legal provisions:
European Patent Convention 1973 Art 84
Keywords: Claims - clarity (no)
Claims - claim must be clear in itself
Catchwords:

-

Cited decisions:
-
Citing decisions:
-

Summary of Facts and Submissions

I. The applicant appealed against the decision of the examining division refusing European patent application No. 05733798.2 on the basis of Article 56 EPC.

II. With the statement setting out the grounds of appeal, the applicant filed sets of claims according to a main request and to an auxiliary request, both being identical, respectively, to the sets of claims according to the main request and the second auxiliary request underlying the appealed decision. The applicant requested that the decision of the examining division be set aside and a patent be granted on the basis of one of these two sets of claims.

III. On 26 April 2017, the board summoned the applicant to attend oral proceedings. In a communication annexed to the summons the board provided its provisional opinion on the merits of the appeal.

IV. In response to the summons to oral proceedings, the applicant filed, with a letter of 13 October 2017, amended sets of claims according to a new main request and a new auxiliary request.

The applicant requested that the decision under appeal be set aside and that a patent be granted on the basis of claims 1 to 13 of the main request or claims 1 to 11 of the auxiliary request, both requests filed with the letter dated 13 October 2017.

V. Subsequently, the applicant's representative informed the board with a letter dated 3 November 2017, that he would not attend the oral proceedings.

VI. Oral proceedings were held on 16 November 2017 in the absence of the applicant.

VII. Independent claim 1 according to the main request reads as follows:

"An optical apparatus comprising:

a MEMS device (203), including a plurality of elements (203-1 to 203-N), which are individually movable; and

a control assembly (207) that is communicatively coupled to the MEMS device (203) and that provides control signals (U1 -UN) to the plurality of elements (203-1 to 203-N) for moving the elements, characterised in that the control signals include feed-forward control signals (Uj) to certain non-moving elements (203-1 to 203-N) that substantially cancel disturbance caused by moving elements."

Independent claim 1 according to the auxiliary request differs from claim 1 of the main request only in that it comprises the following additional feature at the end of the claim:

"... according to the following equation: uj = SUMall k -ajk · Deltauk · g(·),

where element k is a moving element, uj is a feed-forward control signal to a non-moving element j, ajk is a coupling coefficient from element k to element j, Deltauk is the difference between end and start values, and g(·) is a normalized function characterizing disturbance in non-moving elements, wherein the summation is over all k, and wherein akk = 0."

Reasons for the Decision

1. Main request

The subject-matter of claim 1 lacks clarity within the meaning of Article 84 EPC 1973.

1.1 It is unclear in claim 1 what the exact nature of the "feed-forward control signal" is.

Claim 1 lacks a clear technical definition of the actual signal applied to certain non-moving elements (e.g. a clear mathematical expression of the actual control signal) or at least a clear definition of the process for generating the signal (e.g. exercising the device during a preliminary learning process; see page 7, lines 24 to 28 of the application as filed). Merely referring to a general "feed-forward control signal" is not sufficient to ensure the effective cancellation of disturbances over the whole scope of claim 1, which encompasses any nature and type of movement of the elements and any origin and type of disturbances. Claim 1 attempts to define the "feed-forward control signal" in terms of the result that it is supposed to deliver, i.e. "substantially cancel disturbance caused by moving elements", instead of defining it in terms of technical features responsible for achieving the claimed result (Article 84 EPC 1973).

1.2 In its letter of reply dated 13 October 2017, the applicant presented arguments referring to disturbances on non-moving mirrors in an array due to the motion of nearby moving mirrors.

It further argued that "it is not necessary to specify the nature of the disturbance as long as the cause is known" and that "it is not necessary to specify the mathematical expression of the actual control signal so long as it is known".

Finally, the applicant explained how "the first three paragraphs on page 7 of the specification clearly teach the general feed-forward strategy that is implemented by control assembly 207".

1.3 These arguments are not convincing. First of all, the applicant refers to features, such as "mirrors", "in an array", disturbances "due to the motion" and "nearby" mirrors, which are not present in claim 1.

Furthermore, contrary to the applicant's contention, the exact cause of the disturbance is left open in claim 1. Indeed, the wording of claim 1 encompasses not only aerodynamic coupling as mentioned in the description, page 2, lines 11 to 13, but also other causes of disturbance such as causes of disturbance of a mechanical, electrical, optical or thermodynamical nature.

The explanations about the "general feed-forward strategy" provided by the applicant in its letter of reply and based on information taken from the description of the application are also not found convincing, because claims must in principle be clear in themselves when read by the person skilled in the art. Claim 1 does not define any technical features of the feed-forward control signal which are necessary to achieve the claimed result and a person skilled in the art, using normal skills, will not clearly understand from the wording of claim 1 alone how to achieve the result defined in the claim. Therefore, claim 1 in itself is unclear. This clarity deficiency in the claim wording cannot be rectified by the fact that the description could possibly help the reader to understand the technical subject-matter which the claim was intended to define.

1.4 It follows from the above that claim 1 lacks clarity, contrary to Article 84 EPC 1973.

2. Auxiliary request

The subject-matter of claim 1 lacks clarity within the meaning of Article 84 EPC 1973.

2.1 Despite the provision in claim 1 of the mathematical relation defining the feed-forward control signal uj, it is still unclear in claim 1 what the exact nature of the "feed-forward control signal" is (see also point 1.1 above). Indeed, claim 1 does neither define the exact meaning of the parameters ajk, Deltauk and g(·) used in the mathematical relation nor how these parameters are determined. In particular, claim 1 defines the parameter Deltauk as being "the difference between end and start values" without, however, defining the kind of end and start values. The parameters ajk and g(·) are merely designated by the general expressions "coupling coefficient" and "normalized function characterizing disturbance", respectively, without, however, defining the concrete technical meaning of these terms. Therefore, the mathematical relationship is not suitable to clarify the nature of the "feed-forward control signal".

2.2 The applicant, in its letter of reply, explained that "with respect to the "start and end values", one skilled in the art will readily appreciate that these refer to the start and end values of control signal values uk corresponding to the start and end angles thetak for the moving mirror k". The start and end values "can readily be determined, as may be seen from figure 4 and corresponding discussion on page 8 at lines 5-19". Therefore, "Deltauk is basically the amplitude of the signal that causes the motion of element k that causes the disturbance in neighboring mirror j".

Concerning the parameters ajk and g(·), the applicant explained that "from these paragraphs on page 7 [i.e. the first three paragraphs on page 7], one skilled in the art would readily be able to devise" an experimental process for measuring and determining ajk and g(·) via an iterative procedure.

2.3 These arguments are not considered to be persuasive. For explaining the meaning of the parameters ajk, Deltauk and g(·) and the manner of obtaining them, the applicant refers to the abilities of the skilled person to understand the information provided in the description of the patent application. However, the board is not convinced that the skilled person would necessarily interpret the claim wording as suggested by the applicant in its letter of reply. For instance, the coupling between elements of the MEMS device depends on many aspects, such as the distance between the elements, the mechanical structure of the elements or the signal amplitude and duration applied to the elements. Claim 1 leaves open which kind of coupling is to be considered and how the coupling coefficients ajk are effectively computed or measured. A similar lack of information exists concerning the disturbance function g(·). For instance, it is unclear in claim 1 whether parameter g(·) is an angle, a power level or a voltage and how it is computed or measured. Concerning "the end and start values", even if the skilled person would assume that values of control signals are referred to, it remains unclear from the wording of the claim how and at what point in time the end and start values of the control signals are to be computed or measured.

As already mentioned in point 1.3 above, the board is of the opinion that claims must in principle be clear in themselves when read by the person skilled in the art. This is not the case for present claim 1 since the applicant, in its attempt to clarify the wording of claim 1, had to constantly refer to various passages of the description.

Order

For these reasons it is decided that:

The appeal is dismissed.

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