ambiguity in patent claims

[PILCH Hartmut <phm@a2e.de>]

US Patent 5,975,630
Claim 1.  A sun tracking lounge chair, consisting of:
  a base;
  an electric motor drive mounted on the base;
  a chair portion rotably mounted on the base, and being operably attached
    to the motor drive;
  a main solar electric power array electrically coupled to the motor drive
    by a circuit;
  the circuit including a photo transistor switch operable to activate the
    motor drive for a minimum period of five seconds when not exposed to
    sunlight; and
  the circuit further including a timer operable to deactivate the motor
    drive after a predetermined activation period of thirty seconds.

Especially the last two clauses beginning with "the circuit" could be
interpreted in many ways, depending on how the words are grouped.  I.e. it
could be

(the cirucuit including a photo transistor switch) (operable to activate
the motor drive) (for a minimum period of five seconds) (when not exposed
to sunlight)

but it is probably

the circuit (including (a photo transistor switch (operable to (activate
the motor drive (for a minimum period of fife seconds) (when not exposed
to sunlight))))

Usually the right interpretation would be found by looking at the
specification.  This needs a lot of human intelligence which can't be
provided by automatic translation.

Still, in this example the ambiguity is rather easy to resolve based on
some common everyday experience.  It serves only to show the difficulty of
automatic translation.

I hope I can find some better examples soon, especially involving Japanese
patent claims.

--
phm