Saturday 8 January 2011

Interpretative Spotlight: « Angle Sensor »


When expounding claim features in the specification, one often tries to draft very general statements, so as to cover a great variety of embodiments. This practice is not without risks. Should the feature become critical to patentability, the Boards will, as a rule, not accept restrictions with respect to what had been disclosed in the application as filed.

In the present case, the patent proprietor appealed against the revocation of its patent by the Opposition Division (OD).

Claim 1 of the main request read:

Method for operating a milking installation (1) with at least two milking stations (3), arranged on a movable platform (2), in which a change of position of the platform (2) is determined relative to a reference point by means of a position detection unit (8, 15) with the aid of at least one angle sensor (20).

One of the crucial points before the Board is the interpretation of the term “angle sensor”. The description contains some statements on this item:

*** Translation from the German ***

[0026] The angle sensor is preferably a shaft encoder. Here, absolute shaft encoders, but also incremental encoders, can be used. Multi-turn shaft encoders can also be used.

[0027] Preferably, the angle change is determined with at least one angle encoder, especially with an absolute angle encoder. The angle encoder can also be an incremental angle encoder.

[0028] The angle output can be analogous or digital. Angle encoders are advantageous, while in the analogous method, time changes of the signal are possible.

[0029] For example, an optical sensor can also be considered (denkbar) for position determination. For example, on the outer periphery of a carousel, a periodic, for example, sinusoidal or saw tooth thin line can be present, where the local height of the line and angle on the carousel can be assigned unequivocally. By determination of the height of the line with the aid of an optical, magnetic or other sensor, in such a case, an essentially unequivocal assignment of the angle from a measuring signal can be performed.

[2.1] The [patent proprietor] has submitted that the claimed “angle sensor” was defined in paragraphs [0026] to [0028] of the opposed patent and could only be a sensor where the output is an angle. The sensors for position determination mentioned in paragraph [0029] referred to embodiments that were not claimed any longer and did not qualify as angle sensors within the meaning of claim 1.

The Board cannot endorse these explanations. Paragraph [0029] starts with the words “For example, an optical sensor can also be considered (denkbar) for position determination …”; moreover, it is said that “the local height of the line and angle on the carousel can be assigned unequivocally”, and the last sentence adds “By determination of the height of the line with the aid of an optical, magnetic or other sensor, in such a case, an essentially unequivocal assignment of the angle from a measuring signal can be performed.”

It follows, for those skilled in the art, that the sensors mentioned in this paragraph refer to a carousel milking facility and that an angle sensor within the meaning of the claimed invention does not have to directly determine the angle but only has to assign an angle to a measured signal.

Should you wish to download the whole decision (T 151/09, in German), just click here.

To have a look at the file wrapper, click here.

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