Appeal No. 96-3893
Application 08/063,302
consists of alternating layers of a metal magnetic material 2
(i.e., Sendust) and a non-magnetic material (i.e., SiO ). The
2
reason for using Sendust, which has a large saturation magnetic
flux density (B ) (p. 5, lines 22-25), is to avoid magnetic
s
saturation (p. 6, lines 4-6). The Sendust material is provided
in a plurality of layers separated by layers of SiO rather than
2
in a single layer in order to reduce the occurrence of eddy
currents (p. 6, lines 6-8). Terada explains that in a
conventional magnetic head having its entire magnetic core formed
of metal magnetic material, such a Sendust, the result is an
unacceptably high core loss at high frequencies (30-50 MHz)
(p. 3, lines 8-9 and 14-15; p. 6, table). Terada reduces the
high-frequency core loss to an acceptable level by using metal
magnetic material only in the front portions of the magnetic
head; the back portions 9 are formed instead of an "oxide
magnetic material (i.e., ferrite)" material (p. 4, lines 16-17),
which may be polycrystalline ferrite (p. 5, last two lines) and
which has a large characteristic resistance D (p. 6, line 1).
Reading claim 1 onto Terada's magnetic head, the
examiner's position appears to be that Terada's two front
portions, each of which amounts to about a quarter of the
magnetic head structure, correspond to the claimed "first and
-4-
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Last modified: November 3, 2007