T 0434/97 13-10-1998

Summary of Facts and Submissions

I. The appellant (patentee) lodged an appeal against the decision of the Opposition Division revoking the patent No. 0 551 165 granted on the basis of the divisional application No. 93 200 498.9.

The opposition was based on the grounds of opposition laid down in paragraphs (a) and (c) of Article 100 EPC.

The Division held that the claims did not fulfil the requirements of Article 100(c) EPC.

II. The following documents were among others cited during the appeal procedure:

A7: "Concepts about constraint and freedom", a statement of the respondent (opponent) filed with his letter dated 29 April 1996;

D3: DE-A-3 715 698;

DI: US-A-4 153 998; and

DII: US-A-4 451 987.

III. The oral proceedings of the present case and case T 1221/97 were held on the same day, since the patents of both cases had been granted on the basis of divisional applications of the same parent application No. 91 301 477.5 (said application as originally filed is hereinafter called parent application), now patent EP-B-0 445 945.

IV. At the end of oral proceedings, which were held at the same day as those of case T 1221/97, the decision of the Boards has been announced.

The appellant requested that the decision under appeal be set aside, that the patent be maintained in amended form on the basis of a main request or two auxiliary requests and that the appeal fee be reimbursed.

The respondent requested:

(a) that the appeal be dismissed;

(b) apportionment of the costs of the oral proceedings.

V. Claim 1 of the main request reads as follows:

"1. A touch probe for position determining apparatus, comprising:

a fixed member (10) having an axis; a movable member (12) for carrying a workpiece-contacting stylus (14);

bias means (24) for biasing the movable member into a rest position relative to the fixed member, the movable member being movable out of the rest position against the action of the bias means when a force is applied to the stylus;

a detector (42,44,46) for providing a signal when said stylus contacts a workpiece; and

a constraining device between the fixed and movable members for constraining movement of the movable member when it is biased into the rest position; the constraining device including:

an axial constraint including a pair of mutually engageable surfaces (20,22,114), one on the fixed member and one on the movable member, for constraining the movable member axially relative to the fixed member when it is biased into the rest position;

a planar spring (30,54) for preventing rotation of the movable member relative to the fixed member; characterised in that said constraining device further includes:

an intermediate member (32,54) which is movable relative to the fixed and movable members;

support means (32,36,56,58,106,110) additional to the axial constraint, the support means being provided between the intermediate member and the fixed member, and comprising elements on one of said fixed and intermediate members which are engageable with corresponding surfaces on the other one of said fixed and intermediate members, thereby to constrain movement of the intermediate member relative to the fixed member when said elements and surfaces are engaged, the fixed and intermediate members being relatively rotatable when said elements and surfaces are disengaged;

and in that said planar spring (30,54) is provided between the intermediate member and the movable member, for preventing relative rotation therebetween, but permitting axial and tilting movements therebetween while said elements and surfaces of the support means remain engaged."

Claim 1 of the first auxiliary request reads:

"1. A touch probe for position determining apparatus, comprising:

a fixed member (10) having an axis; a movable member (12) for carrying a workpiece-contacting stylus (14);

bias means (24) for biasing the movable member into a rest position relative to the fixed member, the movable member being movable out of the rest position against the action of the bias means when a force is applied to the stylus;

a detector (42,44,46) for providing a signal when said stylus contacts a workpiece; and

a constraining device between the fixed and movable members for constraining movement of the movable member when it is biased into the rest position; the constraining device including:

an axial constraint including a pair of mutually engageable surfaces (20,22,114), one on the fixed member and one on the movable member, for constraining the movable member axially relative to the fixed member when it is biased into the rest position;

a planar spring (30,54) for preventing rotation of the movable member; characterised in that said constraining device further includes:

an intermediate member (32,54) which is movable relative to the fixed and movable members;

support means (32,36,56,58,106,110) additional to the axial constraint, the support means being provided between the intermediate member and the fixed member, and comprising elements on one of said fixed and intermediate members which are engageable with corresponding surfaces on the other one of said fixed and intermediate members, thereby to constrain movement, including rotation, of the intermediate member relative to the fixed member when said elements and surfaces are engaged, the fixed and intermediate members being relatively rotatable when said elements and surfaces are disengaged;

and in that said planar spring (30,54) is provided between the intermediate member and the movable member, for preventing relative rotation therebetween, the planar spring thereby acting with the support means to prevent relative rotation of the movable member relative to the fixed member while said elements and surfaces of the support means remain engaged, but permitting axial and tilting movements between the intermediate member and the movable member while said elements and surfaces of the support means remain engaged."

Claim 1 of the second auxiliary request reads:

"1. A touch probe for position determining apparatus, comprising:

a fixed member (10) having an axis; a movable member (12) for carrying a workpiece-contacting stylus (14);

bias means (24) for biasing the movable member into a rest position relative to the fixed member, the movable member being movable out of the rest position against the action of the bias means when a force is applied to the stylus;

a detector (42,44,46) for providing a signal when said stylus contacts a workpiece; and

a constraining device between the fixed and movable members for constraining movement of the movable member when it is biased into the rest position; the constraining device including:

an axial constraint including a pair of mutually engageable surfaces (20,22,114), one on the fixed member and one on the movable member, for constraining the movable member axially relative to the fixed member when it is biased into the rest position;

a prestressed planar spring (30,54) for preventing rotation of the movable member; characterised in that said constraining device further includes:

an intermediate member (32,54) which is movable relative to the fixed and movable members;

support means (32,36,56,58,106,110) additional to the axial constraint, the support means being provided between the intermediate member and the fixed member, and comprising elements on one of said fixed and intermediate members which are engageable with corresponding surfaces on the other one of said fixed and intermediate members, thereby to constrain movement, including rotation, of the intermediate member relative to the fixed member when said elements and surfaces are engaged, the fixed and intermediate members being relatively rotatable when said elements and surfaces are disengaged;

the elements and surfaces on the fixed and intermediate members being biased into engagement by the prestressed planar spring;

and in that said planar spring (30,54) is provided between the intermediate member and the movable member, for preventing relative rotation therebetween, the planar spring thereby acting with the support means to prevent relative rotation of the movable member relative to the fixed member while said elements and surfaces of the support means remain engaged, but permitting axial and tilting movements between the intermediate member and the movable member while said elements and surfaces of the support means remain engaged;

the mutually engageable elements of the axial constraint being biased into engagement with a lower force than the elements and surfaces on the fixed and intermediate members, whereby upon displacement of the movable member said mutually engageable elements disengage, against said lower bias force, and then subsequently the elements and surfaces on the fixed and intermediate members disengage."

Claims 2 to 8 of all requests are dependent on their respective claim 1.

VI. The arguments of the appellant with respect to the points on which the decision is based are summarized as follows:

The mere use of a planar spring as disclosed in the parent application inevitably leads to the prevention of the rotation of the movable member when the latter is biased into its rest position. Rotation-prevention is a natural property of a planar spring and is used widely, for example in D3. As stated in decision T 37/82, it is sufficient for the disclosure of a technical feature that it can be deduced from the original application on the basis of normal expert considerations.

Furthermore, the probe of DII which is cited in the parent application comprises a planar spring; said probe, when manufactured in accordance with this document, shows rotation-prevention. A7, filed as part of the opponents' arguments, demonstrates (on page 3, at B) that a planar spring provides constraintagainst rotation about an axis (z-axis) perpendicular to the plane of the spring. The sketch of the planar spring with four small spokes which the respondent produced during the oral proceedings has been specially designed so that it does not prevent rotation completely, whereas the planar springs shown in the parent application do not have this special design.

Passages of the decision and of examination minutes of a US District Court in an infringement action against a US patent based on the parent application indicate that the planar spring of the embodiment as shown in Figures 1 and 2 of the patent-in-suit effects constraint.

The dowel is irrelevant in this respect since it has no effect during normal operation, that is when the movable member is biased into the rest position, with the elements and surfaces of the support means engaged.

The decision under appeal sets out only the facts on which the decision is based and the conclusion reached, but there is no logical reasoning how the Opposition Division arrived at its conclusions. This lack of reasoning amounts to a substantial procedural violation, justifying refund of the appeal fee even if the Board would be able to find reasons to uphold the attacked decision.

VII. The arguments of the respondent with respect to the points on which the decision is based are summarized as follows:

Constraintis effected by the dowel and mentioned only in context with the dowel. The same applies to DI (column 4 from line 25 on) which is mentioned in the parent application. The planar spring is provided for lateral constraint only. Constraint of the planar spring cannot be unambiguously and fully derived from the parent application. The respondent never admitted that prevention of rotation is an inherent, natural property of a planar spring or disclosed indirectly in the drawings of the attacked patent. D3 is not within the content of the parent application. Even if the planar spring of DII were adapted to provide rotational constraint this would be irrelevant, since DII does not suggest that this function forms part of the invention. A7 was cited during the opposition proceedings for argumentation independently from the ground of opposition under Article 100(c) EPC.

The statements during infringement litigation in the United States are irrelevant since there the validity of the patent was not attacked and claims of the US patents of the appellant alleged to be infringed by the respondent recite a planar spring between the intermediate member and the movable member, for preventing relative rotation therebetween.

The claims of the second auxiliary request cannot be admitted since they are submitted only during the oral proceedings of the appeal proceedings and thus too late.