Ex parte Cain

Board of Patent Appeals and Interferences

Sep 10, 1998

08078917 (B.P.A.I. Sep. 10, 1998)

Application for patent filed June 21, 1993.1
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today
(1) was not written for publication in a law journal and
(2) is not binding precedent of the Board.
Paper No. 22
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte WILLIAM C. CAIN
_____________
Appeal No. 95-5142
Application 08/078,9171
______________
ON BRIEF
_______________
Before HAIRSTON, KRASS, and MARTIN, Administrative Patent
Judges.
MARTIN, Administrative Patent Judge.
DECISION ON APPEAL
Appeal No. 95-5142
Application 08/078,917
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This is an appeal under 35 U.S.C. § 134 from the
examiner's final rejection of claims 1-7, all of Appellant's
pending claims, under § 103. We reverse.
The invention is described in Appellant's specification
as an improvement on the prior art transducer shown in
Appellant's
Figure 1, which shows an MR (magnetoresistive) read transducer
20 as disclosed in Krounbi et al. U.S. Patent 5,018,037
(Krounbi). The prior art structure is described in
Appellant's specification as follows (at 3, lines 10-23):
A central active layer area region 16 is composed of a
soft adjacent layer 2 separated from an MR layer 6 by a
nonmagnetic spacer layer 4. Passive end regions 18 each
include a hard magnetic biasing layer 10 and a conductive
layer 8. The central active region is defined by the
space between the passive end regions 18.
End regions 18 produce a longitudinal bias field,
while a transverse bias field is produced in at least
part of the central active region 16. Transverse biasing
occurs when a sense current passes through soft adjacent
layer 2. The biasing at least partially compensates for
hysteresis effects, thereby improving linearity and
sensitivity of the signal generated in the transducer.
Krounbi explains that it is necessary to provide both
longitudinal and transverse biasing of the MR layer in order
Appeal No. 95-5142
Application 08/078,917
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to eliminate Barkhausen noise and to maintain the sensor in
its most linear operating range (col. 1, lines 11-14).
Layers 2, 4, and 6 of the prior art device shown in
Appellant's Figure 1 appear as layers 34, 36, and 38,
respectively, in Appellant's Figure 2, which shows his
invention as additionally including an exchange layer 32
adjacent to the biasing layer, i.e, soft adjacent layer 34,
and on the opposite side of the soft adjacent layer from the
spacer layer 36. This exchange layer, which is in electrical
and magnetic continuity with soft active layer, produces a
field transverse to MR layer 38 that enables saturation of the
soft active layer 34 either without a sense current or a
relatively low sense current (Spec. at 3, lines 31-35),
thereby reducing the size of the sense current and thus the
power supply (Spec. at 2, lines 5-11).
As in the prior art device shown in Appellant's Figure 1,
Appellant's transducer includes a hard magnetic bias layer 44
and a conductive layer 42 for generating longitudinal biasing
of the MR layer (Spec. at 4, lines 3-16).
Appeal No. 95-5142
Application 08/078,917
Incorrect copies of claim 1 were submitted with2
Appellant's substitute brief filed April 10, 1995
(hereinafter, Brief), with the letter received (by mail) on
July 22, 1996, and with the letter received (by fax) on
December 11, 1997.
This limitation appears to be inconsistent with3
Appellant's specification, which, as noted earlier, states
that longitudinal biasing is provided by end regions 48 and
that the function of the soft secondary layer and the exchange
layer is to provide transverse biasing.
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Claim 1, the sole independent claim, uses the term "soft
active layer" in place of "soft secondary layer":2
1. A magnetoresistive read transducer for sensing
magnetic signals and converting said signals to
electrical signals, comprising:
a unitary magnetoresistive layer;
a soft active layer for providing a longitudinal
bias to said transducer;[3]
a spacer layer, interposed between said unitary
magnetoresistive layer and said soft active layer; and
an exchange layer, in contact with said soft active
layer and on the opposite side of said soft active layer
from said spacer layer for generating an exchange field
along a direction transverse to said soft active layer,
thereby reducing the sense current required to saturate
said soft active layer;
so that a sense current is generated in said
transducer when said transducer is passed over magnetic
storage media.
We note that the claim does not preclude the MR layer
from being formed of a "soft" magnetic material.
The sole reference relied on by the examiner is:
Appeal No. 95-5142
Application 08/078,917
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Hempstead et al. (Hempstead) 4,103,315 July 25,
1978
Claims 1-7 stand rejected under 35 U.S.C. § 103 as
obvious over the admitted prior art shown in Appellant's
Figure 1 and described at pages 1-2 of the specification in
view of Hempstead.
Inasmuch as Appellant treats all of the appealed claims as
standing or falling together (Brief at 3), we will
specifically discuss only claim 1.
As evidence of the obviousness of adding an exchange
layer to the prior art device show in Appellant's Figure 1,
the examiner cites Hempstead, which discloses magnetic
read/write heads in which the magnetoresistive film is formed
as a single domain by using exchange anisotropy to bias
magnetic films in a unique direction which is defined during
device fabrication (col. 3, lines 41-47). This is
accomplished either by depositing an antiferromagnetic film
onto a ferromagnetic film in the presence of a magnetic field,
or by depositing a ferromagnetic film onto an
antiferromagnetic film followed by heating and cooling the
films in a magnetic field in order to obtain the required
Appeal No. 95-5142
Application 08/078,917
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magnetic spin alignment in the antiferromagnetic film (col. 5,
lines 46-54). Figure 2 shows an embodiment of such a
structure which includes a plurality of ferromagnetic/
antiferromagnetic layer pairs (10,11), (13, 22), (24, 25), and
27, 28) separated by nonmagnetic layers 9, 12, 23, and 26
(col. 10, lines 11-54).
In the final Office action (at 3), the examiner relies on
Figure 2 of Hempstead as follows with respect to
claim 1:"Hempstead et al[.] (US 4,103,315) disclose an
exchange layer 28 which contacts a soft adjacent layer 27 and
is on the opposite side of the soft layer from the spacer
layer 26." With respect to the particular material and
thickness limitations appearing in the dependent claims, the
examiner notes (at 3) that in Hempstead "[t]he exchange layer
is iron manganese and has a thickness of about 150-350
Angstroms; see Figure 5 and column 5, lines 48-57. Hempstead
et al[.] teach an exchange layer which comprises nickel oxide
and an exchange layer comprising cobalt oxide; see column 4,
lines 20-28." As motivation for modifying the prior art
device in view of Hempstead in a way that satisfies claim 1,
the examiner argued that
Appeal No. 95-5142
Application 08/078,917
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one of ordinary skill in the art would have been
motivated to provide the magnetoresistive read transducer
of the Applicant's Prior Art with an exchange layer which
contacts a soft adjacent layer and is on the opposite
side of the soft layer from the spacer layer as shown in
Hempstead et al[.] in order to have fixed the
magnetization of the adjacent layer. [Final Office
action at 3-4.]
Appellant responded with several arguments, one of which
is that Hempstead fails to address the power consumption
problem solved by Appellant's invention (Brief at 5). This
argument is unconvincing because the teachings of the prior
art need not be combined to solve the same problem that is
solved by the claimed invention. In re Beattie, 974 F.2d
1309, 1312, 24 USPQ2d 1040, 1042 (Fed. Cir. 1992).
Appellant also argued (Brief at 6) that the motivation
alleged by the examiner (i.e., fixing the magnetization of the
soft adjacent layer) lacks support and that "the use of
unsupported statements by the Examiner as to the motivation of
one or ordinary skill in the art is improper and should not be
the basis for determining obviousness," citing In re Fritch,
972 F.2d 1260, 1265, 23 USPQ2d 1780, 1783 (Fed. Cir. 1992)
(the examiner can satisfy the burden to make out a prima facie
case for obviousness only by "showing some objective teaching
Appeal No. 95-5142
Application 08/078,917
Appellant's specification (at 5) includes among the4
material suitable for use as the soft magnetic biasing
material Permalloy, which is an 80:20 NiFe alloy (Hempstead,
col. 11, lines 54-56).
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in the prior art or that knowledge generally available to one
of ordinary skill in the art would lead the individual to
combine the relevant teachings of the references)." Actually,
Hempstead does provide support for using an antiferromagnetic
exchange film to fix the magnetization of the soft magnetic
layer. Specifically, as noted above, Hempstead forms the
antiferromagnetic/ferromagnetic film pair in such a way as to
obtain the required magnetic spin alignment in the
antiferromagnetic film (col. 5, lines 46-54). However, we are
not persuaded that Hempstead's invention involves or suggests
using an exchange layer adjacent to a soft magnetic biasing
layer, as required to satisfy the claim; rather, Hempstead
uses an exchange layer adjacent to an MR layer. While
Hempstead's antiferromagnetic FeMn layer 28 (Fig. 2) overlies
a soft magnetic NiFe layer 27 that is suitable for use as a
soft magnetic biasing layer, layer 27 is not described as,4
and does not appear to be, a biasing layer. Nor do we believe
that Hempstead can fairly be construed as suggesting that an
Appeal No. 95-5142
Application 08/078,917
The examiner should consider whether the subject matter5
of Appellant's claims is anticipated by or rendered obvious by
Bajourek et al.
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exchange layer can be used adjacent to any exposed soft
magnetic layer regardless of that latter's function. Indeed,
Hempstead specifically distinguishes his invention in this
respect from Bajourek et al. U.S. Patent 3,840,898, which,
like the claimed invention, employs an exchange layer adjacent
to a soft magnetic biasing layer that is separated from a soft
magnetoresistive (MR) layer by a nonmagnetic layer (Hempstead
at col. 5, lines 10-35):5
Bajourek et al. . . . teach the use of exchange coupling
to produce permanent magnetic bias layers for an MR
stripe. They teach the use of exchange coupling between
an antiferromagnetic layer such as "Fe O and a soft2 3
magnetic material such as 80:20 NiFe to produce a
permanent magnetic film which is then used to bias a
second soft magnetic film (the MR stripe) by
magnetostatic interaction between the two magnetic films
and/or by exchange coupling between the two magnetic
films through an insulating layer, for example, via
pinholes in the insulating layer as described below.
Nowhere do they teach the deliberate exchange between an
antiferromagnetic film and an MR stripe itself [for]
maintaining the soft magnetic properties of the MR
stripe. This is because, in that patent as discussed
above, for all known processes the exchange coupling
between a soft magnetic film and an antiferromagnetic
film caused an increase in the coercivity of the soft
magnetic film making it useless as an MR stripe (which
requires low coercivity and high permeability) but making
Appeal No. 95-5142
Application 08/078,917
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it useful as a permanent magnet film for biasing a second
soft magnetic film which would be the MR stripe as
envisioned in the Bajourek patent.
In discussing the rejection of claim 1 in the Answer (at
4-5), the examiner shifted his reliance on Hempstead's Figure
2 to Figure 5 and gave a different motivation for modifying
the prior art device in Hempstead:
Hempstead et al[.] (US 4,103,315) discloses a
magnetoresistive read transducer having an exchange layer
55 which contacts a soft active layer 54; see Figure 5.
Exchange layers are conventional in the art for capping
various magnetoresistive layers, including soft magnetic
layers, and achieving desired noise characteristics,
saturation levels of layers and overall improved head
response.
. . . .
. . . [O]ne of ordinary skill in the art would have
been motivated to provide the magnetoresistive read
transducer of the Appellant's Prior Art Figure 1 and
pages 1-2 of the specification with an exchange layer
which contacts a soft adjacent layer in order to have
utilized the exchange layer for capping the soft active
layer and keeping the soft layer in saturation.
Although Appellant did not file a reply brief addressing this
new rationale, we have considered it on the merits and find it
unpersuasive. To the extent the examiner is arguing that
Hempstead suggests using an exchange layer adjacent to a soft
magnetic biasing layer or adjacent to any exposed soft
magnetic layer regardless of its purpose, we disagree for the
reasons already discussed. The examiner's alternative
Appeal No. 95-5142
Application 08/078,917
Of course, supporting references should be cited prior6
to the Answer unless they are cited in support of a new ground
of rejection given in the Answer.
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contention that "[e]xchange layers are conventional in the art
for capping various magnetoresistive layers, including soft
magnetic layers, and achieving desired noise characteristics,
saturation levels of layers and overall improved head
response" (Answer at 4) will not be considered, because it is
not supported by a citation to a specific part of Hempstead or
to another reference. Such a citation is necessary where, as
here, the allegedly well known subject matter is highly
technical. Compare In re Pardo, 684 F.2d 912, 917, 214 USPQ6
673, 677 (CCPA 1982), which quotes In re Ahlert, 424 F.2d
1088, 1091, 165 USPQ 418, 420-21 (CCPA 1970) as follows:
Assertions of technical facts in areas of esoteric
technology must always be supported by citation to some
reference work recognized as standard in the pertinent
art and the appellant given, in the Patent Office, the
opportunity to challenge the correctness of the assertion
or the notoriety or repute of the cited reference. Cf.
In re Cofer, 53 CCPA 830, 354 F.2d 664, 148 USPQ 268
(1966), In re Borst, 52 CCPA 1398, 345 F.2d 851, 145 USPQ
554 (CCPA 1965). Allegations concerning specific
"knowledge" of the prior art, which might be peculiar to
a particular art, should also be supported and the
appellant similarly given the opportunity to make a
Appeal No. 95-5142
Application 08/078,917
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challenge. See In re Spormann, 53 CCPA 1375, 363 F.2d
444, 150 USPQ 449 (1966).
In the absence of reference support for the examiner's
assertion that is was known to use an exchange layer for
capping the soft active layer and keeping the soft layer in
saturation, the examiner has failed to prima facie establish
that this knowledge would have motivated one skilled in the
art to add an exchange layer adjacent to the to soft adjacent
layer in the prior art device shown in Appellant's Figure 1.
For the foregoing reasons, the rejection of claim 1 under
35 U.S.C. § 103 for obviousness over Appellant's prior art
Figure 1 in view of Hempstead is reversed, as is the rejection
of dependent claims 2-7, which stand or fall (in this case
stand) therewith.
REVERSED
)
KENNETH W. HAIRSTON )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
ERROL A. KRASS )
Administrative Patent Judge ) APPEALS AND
Appeal No. 95-5142
Application 08/078,917
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)
) INTERFERENCES
)
JOHN C. MARTIN )
Administrative Patent Judge )
sd
Appeal No. 95-5142
Application 08/078,917
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Nathan N. Kalman
20900 Sarahills Drive
Saratoga, CA 95070
Appeal No. 95-5142
Application 08/078,917
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