Appeal No. 2003-0749 Page 4
Application No. 09/332,070
becomes a solid and fixes the electrode 48 against rotation
relative to the housing so that the reel shaft 26 and reel 24
are in turn locked against belt winding and unwinding
rotation.
When the inertia condition ceases, the voltage is
removed, and the electro-rheological fluid 62 returns from
the solid condition to the fluid condition permitting normal
winding and unwinding rotation.
It will be understood that the programming unit 66
may be constructed to vary the voltage applied to the
electro-rheological fluid 62 so that the locking force applied
to the electrode is varied to obtain a desired locking
characteristic of the retractor.
Blake differs from the invention recited in independent claims 1, 13 and 20 in two
ways. First, Blake’s locking device uses electro-rheological fluid rather than magneto-
rheological fluid as called for in appellants’ claims. Second, Blake’s electrical controller
sends a signal to generate an electric field which turns the electro-rheological fluid to a
solid and locks the reel shaft and reel against winding and unwinding rotation; it thus
does not increase the apparent viscosity of the fluid to a viscosity which permits some
unwinding of the seat belt, as called for in appellants’ claims.
The examiner does not acknowledge this second difference. On this point, the
examiner (answer, pages 5-6) states that
[i]t is inherent that for any given situation, a voltage between
zero and the high voltage would produce a state in which the
ER fluid effects damping of the reel. Furthermore, on the
way to the high voltage and the solid state, the voltage has
gone through some intermediate voltages where the fluid
has higher viscosity and therefore has effected damping. A
high voltage for effecting a solid state for a seated occupant
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