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not look to Schutten to teach placing force actuators in between two frames. Specifically, van
Engelen fails to explain why Schuffen's force actuators would not work in between two frames.
Schutten teaches a force actuator system for compensating for forces acting on the frame
(stage/table), or for tilting of the frame and for movement of the stage. Based on the record
before us, such a system teaches a compensation system regardless of whether that system is
placed in between two frames, or in between a frame and the ground. Note, absent from van
Engelen's claims 5, 13, 15, and 16 is a requirement that the compensation force compensate for
reaction forces in a second frame. Rather the claims recite that the compensation force
compensate for forces of gravity acting on the object table (substrate holder/mask holder).
Schutten apparently compensates for such forces. Van Engelen has failed to direct us to evidence
that demonstrates otherwise.
Van Engelen argues that the prior art fails to disclose a compensation force exerted in
response to gravity forces on two moving stages as recited in claim 13 (opposition at 2 1). Claim
13 recites that the mechanical moments of the forces of gravity for both the mask holder and
substrate holder are added in deter-mining the opposing compensation force exerted on the
reference frame. Van Engelen argues that Schutten only provides background information and
does not teach a compensation force in response to gravity forces exerted on a substrate holder
and a mask holder (opposition at 22). Van Engelen's response is dissatisfying.
In its preliminary motion, Lee explains that van Engelen claim I I recites that the mask
holder and the substrate holder are both supported on a common support - the machine frame.
The claimed compensation force exerted in van Engelen claim 13 takes into account the sum of
all forces acting on that common frame - from both the substrate and mask holders/tables. Lee
explains that, although the Schutten reference fails to disclose two stages, Schutten does teach
summing all of the forces acting on the supporting frame to arrive at the compensation force.
Lee then concludes that one of ordinary skill would have been motivated to use the Schutten
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