Appeal No. 96-3833
ApplicationApplication 08/014,320
modification required by the claims. In re Lalu, 747 F.2d 703,
705, 223 USPQ 1257, 1258 (Fed. Cir. 1984).
In the present case, the Kampe patent teaches that the PTC
heating element is self-regulating in the sense that the
electrical resistance of the PTC material increases substantially
upon reaching a critical temperature to effectively turn off the
heating element. Self-regulating PTC heating elements are known
in the prior art to have the advantage over conventional heaters
of the type disclosed in the VanSickle patent in that they
eliminate the need for a separate thermostatic control.
Inasmuch as the advantages and disadvantages of a PTC
heating element and a heating element with a separate
thermostatic control are well known, the selection of one or the
other for a particular installation would have been merely a
matter of choice or engineering design. See In re Heinrich, 268
F.2d 753, 756, 122 USPQ 388, 390 (CCPA 1959). Certainly, the
elimination of the need for a separate thermostatic control would
have been ample motivation for one of ordinary skill in the art
to replace VanSickle’s thermostatically controlled heating
element with Kampe’s PTC heating element. It therefore would
have been obvious without recourse to appellant’s disclosure to
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