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Ex parte OHTA et al. - Page 6
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Board of Patent Appeals and Interferences > 1998 > Ex parte OHTA et al. - Page 6
Appeal No. 95-2427
Application 08/013,987
it is known that the amount of rare earth can be set at the high end of the range from .15
at.% to 35 at.% and still maintain perpendicular anisotrophy.
With respect to the value of “x” it is generally known that Gd contributes to
increasing the Kerr angle of rotation (resulting in higher S/N) but has the disadvantage of
increasing the curie [sic, Curie] point and depressing the coerceive force. Tb, on the other
hand, contributes to a high coercive force and low curie [sic, Curie] temperature, but has
the disadvantage of a low Kerr angle of rotation. For example, see Denwa <686 where
GdFe has a much higher S/N ratio than Tb Fe or DyFe, (Fig. 2); Tanaka et al <238 which
teaches that in “GdTbFe systems ... Gd or Co may [be] included for the purpose of
improving their reproducing characteristics ...” (C.2: 53-55), and finally Imamura, N[.] et
al (R) “[i]t is clear from these figures that Gd and Co have the remarkable effect of
increasing [Kerr rotation], mainly due to the increase in Tc [sic, T ].” (p. 1607-1608).
c
Thus, from the above citations it is suggested that Gd and Tb relative to each other
and to the amount of Fe are result effective parameters dependent upon the desired
coercivity, Kerr rotation angle, and curie [sic, Curie] temperature. In light of this, it would
have been obvious, [sic] to one skilled in the art of magetooptics to adjust the amount of
each element to optimize desired recording properties. The motivation to optimize the
proportion of each alloy rests with the broad teachings that the amunt of rare earth should
be between 15 at.% to 35 at.%, and the narrower disclosures teaching that Gd enhances
the Kerr rotation angle. Thus, one would be motivated to add as much Gd as is optimum
to enhance the Kerr rotation angle, even at the expense of reduced Hc [sic, H ] and
c
greater Tc [sic, T ].
c
We find the examiner’s analysis to be insufficient to present a prima facie case of obviousness.
While a person skilled in the art may have been motivated to optimize the Kerr rotation angle by adding
Gd, the analysis fails to explain how optimization would have led such a person to the claimed range for
the value of x. Moreover, we do not find that Gardner, Imamura and Tanaka make up for the deficiencies
of the combined teachings of Denwa and Takahashi.
For the foregoing reasons, the rejection of the claims under 35 U.S.C. § 103 as being unpatentable
over the teachings of Denwa, Gardner, Tanaka, Imamura and Takahashi is reversed.
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