Omega ./. Montres Tudor et al. — Finding balance …

Case No. O2015_008 ¦ Decision of 14 March 2018 ¦ ‘Balancier de montre’

Omega logo

We have reported on the background of this case and the main hearing on this Blog here. In brief, infringement of Omega‘s EP 1 837 719 B1 is at stake; see EPO Register and Swissreg for further bibliographic details.

The single independent claim 1 as granted reads as follows:

Balance for a timepiece movement including a felloe (3), arms (4) connecting the felloe (3) to the balance staff and inertia blocks (11) for adjusting the unbalance and regulating the moment of inertia, characterized in that the felloe (3) includes studs (7) directed inwards, a threaded hole (9) into which said inertia blocks (11) are screwed from the inside, passing through said felloe (3) and said studs (7).

This is best understood with the figures of the patent at hand:

Tudor logo

The attacked embodiments are Tudor‘s calibres MT5621 and MT5612. Defendants Tudor and Detech denied infringement and countersued for invalidity.

Let’s get to the details now, at least to some extent. The decision is a booklet of 58 pages, and I will thus only comment on what I believe are the most relevant issues of the case.

The requests

Faced with a counterclaim for invalidity, Omega defended the patent substantially as granted as the main request (MR; see the slight amendment in feature #5, below), and with two auxiliary requests (AR1 and AR2) to a more limited extent only. In the feature analysis below, claim 1 according to the MR is structured into features 1-7. Claim 1 according to AR1 comprises features 1-8, and AR2 comprises features 1-9, respectively.

1 Balancier pour mouvement d’horlogerie Balance for a timepiece movement
2 comportant une serge (3) including a felloe (3)
3 des bras (4) reliant la serge (3) à l’axe de balancier arms (4) connecting the felloe (3) to the balance staff
4 et des masselottes (11) permettant d’ajuster le balourd et de régler le moment d’inertie and inertia blocks (11) for adjusting the unbalance and regulating the moment of inertia
5 caractérisé en ce que la serge (3)  comporte des plots (7) dirigés radialement1 vers l’intérieur characterized in that the felloe (3) includes studs (7) directed radially1 inwards
6 ladite serge (3) et lesdits plots (7) étant traversés par un trou taraudé (9) a threaded hole (9) passing through said felloe (3) and said studs (7)
7 dans lequel lesdites masselottes (11) sont vissées depuis l’intérieur into which said inertia blocks (11) are screwed from the inside
8 les masselottes peuvent être mues indépendamment les unes des autres2 the inertia blocks can be moved independently of each other2
9 le serge présente unse surface externe de diamètre constant sur tout son pourtour3 the felloe has an external surface of constant diameter all around its circumference3

1 Note that ‘radialement’ / ‘radially’ is not included in claim 1 as granted.
2 Additional feature of claim 1 in AR1 vis-à-vis the MR.
3 Additional feature of claim 1 in AR2 vis-à-vis AR1.

Omega’s requests for injunctive relief are adapted accordingly in MR, AR1 and AR2, to conform with the respective requests to maintain the patent. The requests for injunctive relief additionally refer to an illustration of the attacked embodiment that is reproduced below. However, I have amended the reference numbers in accordance with those used in the patent.

Illustration of the claim features included in the requests for injunctive relief

The element marked-up with ‘Δ’ in the above illustration refers to a feature which was not literally fulfilled by the attacked embodiment, but for which infringement under the DoE was alleged, i.e. feature #7 in the table above:

the inertia blocks (11) are screwed [into the threaded hole (9)] from the inside

Rather, the request for injunctive relief read as follows:

les masselottes sont dépourvues de tête et dotées de lobes internes permettant leur vissage depuis l’extérieur de la serge

I.e., in English language:

the inertia blocks are headless and equipped with internal lobes allowing them to be screwed from outside the felloe

Claim construction re feature #7

Now, what does it mean in French that

les masselottes sont vissées depuis l’intérieur?

Does it only require that the inertia blocks can be adjusted from the inside, irrespective of how / from which direction they had been initially placed in the hole, i.e. from the inside or outside of the felloe? Or is it mandatory that the inertia blocks at least could have been placed in the hole from inside of the felloe? Note that EP’719  only discloses inertia blocks with heads (13) that cannot go through the hole, i.e. they must be / have been placed from inside of the felloe; see e.g. ¶[0010].

Anyway, I leave this tricky linguistic question to the francophones to decide for themselves. The decision holds that this feature #7 only requires that the inertia blocks could have been inserted and screwed from the inside during the assembly of the balance wheel (by an access between the serge and the centre of the serge) in the hole traversing the stud and the felloe.

Consequently, feature #7 does not cover inertia blocks which, already present in the tapped holes of the serge and the studs, can be screwed from the inside for the purpose of adjusting the inertia and unbalance, but which would not have previously been inserted and screwed into the corresponding hole from the inside of the felloe.


The balance wheel in DE 864 827 comprises a stud (‘plot’) in the sense of feature #5; see the section 1g in the figures below . But since the screws with the inertia blocks have a head on the outside of the felloe, they do not meet the definition of feature #7 as construed above.

Novelty over DE 864 827 was thus acknowledged.

On the other hand, the balance wheel of US 759,914 has inertia blocks must have been placed from the inside; see the screw head on the inner side of the felloe in the figures below.

But what is missing here is the stud (‘plot’) according to feature #5. Thus, novelty was acknowledged over US 759,914.

The balance wheel of US 2,958,997 has some axial screws (21) which are not inertia blocks. On the other hand, it is not possible that the inertia blocks (3) have been placed from the inside since the screw head is outside of the felloe.

US 2,958,997 (Fig. 4)

Features #6 and #7 were not considered anticipated, and novelty was thus acknowledged.

Finally, novelty over the balance wheel ‘Jean Martin’ is discussed, a photograph of which is reproduced in the decision (don’t blame me for the poor quality, it’s in the original):

Balance wheel ‘Jean Martin’

Here, the studs are arranged axially on top of the felloe. The hole thus only passes through the stud, not through the felloe. Features #6 and #7 were not considered anticipated, and novelty was thus acknowledged.

Inventive step

Inventive step has been assessed on the basis of US 759,914 as closest prior art; see figures above. The distinguishing features are #6 and #7, i.e. the studs (which are directed inwards), and the inertia blocks arrangeable in a hole through the stud (and the felloe) from the inside.

Following Omega’s proposal, the objective technical problem has been defined as follows:

Increasing the diameter of a balance wheel without modifying its inertia.

Now, here is the definition of a stud (‘plot’) according to Berner (FR/EN):

Petite pièce métallique, généralement cylindrique qui sert de butée ou qui renforce la partie d’une pièce qui doit recevoir une goupille ou une vis.

Small metal part, usually cylindrical, used as a stop or as a means of strengthening a part that takes a pin or screw.

It is held in the decision that, with this skilled person’s knowledge in mind, it was obvious to arrange studs on the felloe to reinforce the holes. But on which side? On the inside or the outside of the felloe? When placed on the inside, the diameter of the felloe can be larger. Anyway, with reference to T107/02 and T739/08, it is held that a choice from a very limited number of alternatives without an unexpected effect cannot be considered inventive.

The auxiliary requests did not succeed, either. As to AR1, the inertia blocks can be moved independently of each other already in US 759,914. As to AR2, the felloe has an external surface of constant diameter all around its circumference already in US 759,914.

Late request – belated?

Omega had filed yet another, even more limited auxiliary request (AR3) with the response to the expert opinion of the judge-rapporteur. This request was not admitted into the proceedings anymore, with reference to O2015_012. In particular, the decision holds that the expert opinion did not contain new facts or arguments of a technical nature which had not been argued by the parties.

In a nutshell

Omega’s claim for infringement has been rejected, Tudor’s / Detech’s counterclaim for invalidity has been allowed and EP(CH) 1 837 719 B1 declared invalid.

The decision can still be appealed to the Supreme Court.

Reported by Martin WILMING


Case No. O2015_008 ¦ Decision of 14 March 2018 ¦ ‘Balancier de montre’

Omega S.A.


  1. Montres Tudor S.A.
  2. Detech S.A.


  • Dr. Mark SCHWEIZER
  • Frank SCHNYDER
  • Dr. Tobias BREMI
  • Dr. Philippe DUCOR
  • Christoph MÜLLER


  • Frank SCHNYDER

Court Clerk:


Representative(s) of Plaintiff:

Representative(s) of Defendants:


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