Ex Parte Hau et al

Board of Patent Appeals and Interferences

May 8, 2009

10970596 (B.P.A.I. May. 8, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte MARVIN G. HAU, DALE R. SULLIVAN, and
ARIVIN K. KALIMUTHU
____________

Appeal 2009-1456
Application 10/970,596
Technology Center 2800
____________

Decided:1 May 8, 2009
____________

Before JOHN A. JEFFERY, KARL D. EASTHOM, and ELENI MANTIS
MERCADER, Administrative Patent Judges.

JEFFERY, Administrative Patent Judge.

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, begins to run from the decided date
shown on this page of the decision. The time period does not run from the
Mail Date (paper delivery) or Notification Date (electronic delivery).
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DECISION ON APPEAL
Appellants appeal under 35 U.S.C. § 134 from the Examiner’s
rejection of claims 1-8 and 16-21. We have jurisdiction under 35 U.S.C.
§ 6(b). We affirm.

STATEMENT OF THE CASE
Appellants invented a load dump circuit and method for protecting
circuit components from damage due to excessively high voltages on a
power supply line. The circuit and method include a comparator that
receives a reference signal and a trigger signal indicating the voltage on the
power supply line. The output of the comparator connects to a switch. The
switch is turned on when the voltage increases above a certain level and is
turned off when the voltage decreases below another level. This
arrangement allows for greater use of lower voltage components, lowers the
costs, and simplifies the system.2 Independent claim 1 is reproduced below:
1. A load dump protection circuit for protecting circuit
components from damage due to excessively high voltages on a power
supply line, comprising:

a power supply line for supplying operating power to electrical
components subject to failure if the voltage on said power supply line
exceeds a predetermined level;

a switch including a control terminal, a first output terminal and
a second output terminal;

a common return;

2 See generally Spec. ¶¶ 7, 9, 19, and 20.
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a clamp circuit coupled between said power supply line and
said first output terminal of said switch, wherein said second output
terminal of said switch is coupled to said common return;

a comparator including a first input, a second input and an
output, wherein said output of said comparator is coupled to said
control terminal of said switch, said first input of said comparator is
coupled to said power supply line to monitor the voltage level of a
trigger signal on said power supply line, and said second input of said
comparator receives a reference signal having a reference level, and
wherein said comparator provides a first control signal on said control
terminal that causes said switch to provide a low impedance path
between said first and second output terminals when the voltage level
of the trigger signal increases above the voltage level of the reference
signal indicating the voltage on said power supply line has reached
said predetermined level, and wherein said comparator provides a
second control signal on said control terminal that causes said switch
to provide a high impedance path between said first and second output
terminals when the voltage level of the trigger signal decreases below
a shut-off voltage level that is less than the reference level voltage.

The Examiner relies upon the following as evidence in support of the
rejection:
Parker US 4,181,863 Jan. 1, 1980
Whidden US 4,905,115 Feb. 27, 1990
Kurachi US 5,777,506 July 7, 1998
Heinisch US 6,727,555 B2 Apr. 27, 2004

(1) Claims 1-3, 5, 6, 16, 17, 19, and 20 stand rejected under 35 U.S.C.
§ 103(a) as being unpatentable by Heinisch and Whidden (Ans. 3-7).
(2) Claims 4 and 18 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable by Heinisch, Whidden, and Parker (Ans. 7-8).
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(3) Claim 7 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable by Heinisch, Whidden, and Kurachi (Ans. 8).
(4) Claim 8 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable by Heinisch, Whidden, Kurachi, and Parker (Ans. 8-9).
(5) Claim 21 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable by Heinisch, Whidden, Parker, and Kurachi (Ans. 9-10).
Rather than repeat the arguments of Appellants or the Examiner, we
refer to the Briefs and the Answer3 for their respective details. In this
decision, we have considered only those arguments actually made by
Appellants. Arguments, which Appellants could have made but did not
make in the Briefs, have not been considered and are deemed to be waived.
See 37 C.F.R. § 41.37(c)(1)(vii).
Appellants group claims as follows: (1) claims 1-3, 5, 6, 16, 17, 19,
and 20; (2) claims 4 and 18; (3) claim 7; (4) claim 8; and (5) claim 21 (App.
Br. 10-16). Each grouping will be addressed separately.

Claims 1-3, 5, 6, 16, 17, 19, and 20
Claims 1-3, 5, 6, 16, 17, 19, and 20 are rejected under 35 U.S.C.
§ 103(a) as being unpatentable by Heinisch and Whidden (Ans. 3-7). The
Examiner finds that Heinisch discloses all the limitation of representative

3 Throughout the opinion, we refer to: (1) the Appeal Brief filed October 8,
2007; (2) the Examiner’s Answer mailed April 2, 2008 and supplemented
May 12, 2008; and (3) the Reply Brief field May 22, 2008.

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claim 1,4 except the recited comparator (Ans. 3-5). The Examiner relies on
Whidden to teach incorporating Whidden’s trigger circuit into Heinisch’s
trigger circuit to provide a circuit immune to rapid changes of the power
line’s state (Ans. 5-6). Appellants argue that: (1) Heinisch is a complete
circuit without need for modification; (2) Whidden’s discussion related to an
undervoltage protection circuit teaches away from combining with
Heinisch’s overvoltage protection circuit and destroys the intended purpose
of Heinisch; (3) the combination of Heinisch and Whidden does not teach a
comparator that controls the switch to provide low and high impedance paths
based on the trigger signal recited in claim 1; and (4) the Examiner is
engaging in impermissible hindsight (App. Br. 10-14; Reply Br. 2-4).

ISSUES
The following issues have been raised in the present appeal:
(1) Under § 103, have Appellants shown that the Examiner erred in
finding Heinisch and Whidden collectively teach the recited comparator that
controls the switch to provide a low impedance path or a high impedance
path between the switch’s output terminals depending on the trigger signal’s
voltage level in rejecting claim 1?
(2) Have Appellants shown that Whidden’s discussion related to an
undervoltage protection circuit teaches away from substituting Whidden’s
comparator with Heinisch’s trigger circuit?

4 Appellants argue independent clams 1 and 16 together and group
dependent claims 2, 3, 5, 6, 16, 17, 19, and 20 (App. Br. 10-14).
Accordingly, we select independent claim 1 as representative. 37 C.F.R.
§ 41.37(c)(1)(vii).
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FINDINGS OF FACT
The record supports the following findings of fact (FF) by a
preponderance of the evidence.
Heinisch
1. Heinisch discloses a load dump protection circuit 1 that protects
electronic components from overvoltage of a motor vehicle’s generator
voltage VGen on a supply line. (Heinisch, col. 1, ll. 6-31 and col. 3, ll. 12-15;
Fig. 1a).
2. Heinisch discloses the circuit 1 includes a MOSFET transistor 2
connected to the power voltage source VGen, a trigger circuit 3, and a Zener
diode 4 connected to the transistor 2. The trigger circuit 3 activates or
switches the transistor 2 when the overvoltage of the source VGen reaches a
predetermined voltage value. (Heinisch, col. 3, ll. 16-31; Figs. 1a-b).
3. Heinisch describes and shows the details of the trigger circuit 35
that switches the transistor 2 when the voltage on the source VGen reaches a
predetermined voltage value. The circuit 3 includes back-to-back
transistors, where the signal from the power voltage source VGen feeds into
the transistors and the signal from another Zener diode also feeds into one of
the back-to-back transistors. The output of trigger circuit 3 is sent to
transistor 2. (Heinisch, col. 3, ll. 19-22; Fig. 2).
4. Heinisch states the invention is not limited to the described
embodiment and may be modified in many different ways. (Heinisch, col. 4,
ll. 62-64).

5 Reference numeral 3 in Figure 2 points to the incorrect dotted box. Figures
1a-c clearly show the trigger circuit 3 is separate from transistor 2. We
presume, therefore, that the arrow for the reference numeral 3 was intended
to point to the inner dotted box.
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Whidden
5. Whidden teaches circuit 1 connected to an automobile’s power
source and includes voltage comparator IC1 with an inverting input terminal
3, a non-inverting input terminal 2, and an output terminal 7 coupled to the
gate terminal of SCR1. SCR1 is turned on by a signal from the output
terminal and acts like a switch when the supply voltage level is less than a
predetermined threshold. (Whidden, col. 1, ll. 40-49, col. 2, ll. 29-43, col. 2,
l. 58 – col. 3, l. 45, and col. 4, ll. 60-66; sole figure).

Specification
6. The Specification does not define a comparator. See generally
Specification.

PRINCIPLES OF LAW
During examination of a patent application, a claim is given its
broadest reasonable construction “in light of the specification as it would be
interpreted by one of ordinary skill in the art.” In re Am. Acad. Of Sci. Tech
Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004) (internal quotation marks and
citations omitted).
Discussing the question of obviousness of a patent that claims a
combination of known elements, KSR Int’l v. Teleflex, Inc., 550 U.S. 398
(2007), explains:
if a technique has been used to improve one device, and a
person of ordinary skill in the art would recognize that it would
improve similar devices in the same way, using the technique is
obvious unless its actual application is beyond his or her skill.
Sakraida [v. AG Pro, Inc., 425 U.S. 273 (1976)] and
Anderson's-Black Rock[, Inc. v. Pavement Salvage Co.,
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396 U.S. 57 (1969)] are illustrative—a court must ask whether
the improvement is more than the predictable use of prior art
elements according to their established functions.
KSR, 550 U.S. at 417.
If the Examiner’s burden is met, the burden then shifts to the
Appellant to overcome the prima facie case with argument and/or evidence.
Obviousness is then determined on the basis of the evidence as a whole and
the relative persuasiveness of the arguments. See In re Oetiker, 977 F.2d
1443, 1445 (Fed. Cir. 1992).

ANALYSIS
Heinisch discloses a load dump protection circuit 1 that protects
circuit components from overvoltage or damage due to excessively high
voltages on a power supply line (FF 1). Heinisch discloses the circuit
includes a transistor or switch 2 and trigger circuit 3 that switches the
transistor 2 when the voltage of the source VGen or a trigger signal reaches a
predetermined voltage level (FF 2). The Examiner states Heinisch does not
disclose a comparator as claimed (Ans. 5) or the details of the trigger circuit
3 (Ans. 11). However, upon further review, Heinisch does disclose details
of the trigger circuit 3 in Figure 2 (FF 3; Reply Br. 2).
Heinisch describes Figure 2 as an illustration of the trigger circuit 3
that activates or switches the transistor 2 when the overvoltage of the supply
voltage VGen reaches a predetermined voltage value (FF 3). Figure 2 of
Heinisch shows how trigger circuit 3 activates switch 2 during overvoltage
or when there are excessively high voltages on the power supply line. (Id.)
In particular, Heinisch discloses back-to-back transistors that receive a fixed
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or reference signal (e.g., signal from Zener diode 4) and another signal from
the power supply line connected to VGen or a trigger signal. (See id.) Using
these input signals, an output or control signal is sent to transistor 2. (See
id.) When the control signal reaches a predetermined voltage value or level,
the transistor or switch 2 is activated. (See FF 2-3). Thus, the trigger circuit
3 of Heinisch must make some comparison between the reference signal sent
by the Zener diode 4 and the trigger signal sent by the power supply line in
order to determine when overvoltage occurs or the supply voltage reaches a
predetermined voltage value. Essentially, Heinisch’s trigger circuit 3 is a
comparator circuit or comparator.
Additionally, in order to activate Heinisch’s switch 2 or to allow
current to flow, a low impedance path between the switch’s output terminals
must be created when the voltage level of the trigger signal increases above
the predetermined voltage value or the voltage level of the reference. (See
id.) Moreover, a high impedance path between the switch’s output terminals
is created when the switch 2 is not activated or when the voltage level of the
trigger signal decreases below any value less than the predetermined value
(e.g. any value less than the reference voltage level) or a shut-off voltage
level. (See id.) Thus, Heinisch discloses a trigger circuit 3 that operates and
behaves as the claimed comparator behaves.
Moreover, the Specification provides no special definition of the term
“comparator” (FF 6). Appellants have also not provided any evidence that
the term “comparator” has a particular meaning to an ordinarily skilled
artisan. See App. Br. 10-14; Reply Br. 1-4. Thus, giving the term
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“comparator” it broadest reasonable interpretation, we find that the trigger
circuit 3 of Heinisch discloses the comparator recited in claim 1. See Am.
Acad. Of Sci. Tech, 367 F.3d at 1364.
Since Heinisch discloses all the features of claim 1, including the
recited comparator that controls the switch to provide a low impedance path
and a high impedance path between the switch’s output terminals depending
on the trigger signal’s voltage level, we find Whidden is cumulative.
Nonetheless, Heinisch teaches the invention is not limited to the
embodiment described and may be modified in many different ways (FF 4).
Therefore, contrary to Appellants’ assertions (App. Br. 11-12 and Reply Br.
4), Heinisch welcome additions or modification to the circuit’s components.
Whidden teaches that voltage comparators, like comparator IC1, are known
components for accepting a reference signal at terminal 3 and another signal
at terminal 2 and outputting a signal at terminal 7 to activate or trigger
switch SCR1 at a given voltage condition (FF 5). Thus, Whidden teaches
alternative circuitry in the form of a comparator known to receive a
reference and trigger signal as inputs and to output a signal for triggering a
switch at a predetermined voltage condition. Given Whidden’s disclosure,
an ordinarily skilled artisan armed with its teachings would have recognized
the substitution of a comparator for the back-to-back transistors in Figure 2
of Heinisch would yield no more than the predictable result of turning
Heinisch’s switch 2 on when the predetermined voltage level in Heinisch is
reached. See KSR, 550 U.S. at 416.
We acknowledge Whidden’s comparator is used to trigger the switch
SCR1 when the voltage is less than a predetermined level (FF 5) rather than
when the voltage is increase above a predetermined voltage level as claim 1
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requires. However, Whidden is solely being relied upon to teach that
comparators are known circuitry used with automobile power sources (FF 5)
to compare signals and control a switch under certain voltage conditions.
Based on Whidden’s teaching and one’s background knowledge, one skilled
in the art would have appreciated that comparators are known to behave
similarly to the back-to-back transistors of Heinisch’s trigger circuit and,
thus, can substitute for the transistors in turning the switch 2 on when
overvoltage occurs. Such a combination would predictably result in a
comparator functioning in the same manner as the trigger circuit 3 of
Heinisch. Moreover, such a substitution would simplify the circuit and
make the circuit cheaper by replacing two transistors with one component or
a comparator. See Dystar Textilfarben Gmbh & Co. v. C. H. Patrick Co.,
464 F.3d 1356, 1358 (Fed. Cir. 2006). Thus, we do not find the combination
teaches away from the overvoltage response of Heinisch’s triggering circuit
3 or destroys Heinisch’s intended purpose (App. Br. 11-12).
For the foregoing reasons, Appellants have not shown the Examiner
erred in rejecting claims 1-3, 5, 6, 16, 17, 19, and 20 under 35 U.S.C. § 103
based on Heinisch and Whidden.

Claims 4 and 18
The Examiner finds that Heinisch, Whidden, and Parker collectively
teach all the limitations of representative claim 46 (Ans. 7-8). Appellants do
not present new arguments with respect to claim 4. Rather, Appellants state
that claim 4 depends from claim 1 and repeat that: (a) Heinisch and Whidden

6 Appellants group claims 4 and 18 (App. Br. 14). Accordingly, we select
claim 4 as representative. 37 C.F.R. § 41.37(c)(1)(vii).
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fail to teach each and every element of claim 1; (b) Whidden teaches away
from the claimed invention; and (c) the combination of Heinisch and
Whidden are based on impermissible hindsight (App. Br. 14). We are not
persuaded for the reasons discussed above in connection with claim 1.

Claim 7
The Examiner finds that Heinisch, Whidden, and Kurachi collectively
teach all the limitations of claim 7 (Ans. 8). Appellants do not present new
arguments with respect to claim 7. Rather, Appellants state that claim 7
depends from claim 1 and repeat that: (a) Heinisch and Whidden fail to teach
each and every element of claim 1; (b) Whidden teaches away from the
claimed invention; and (c) the combination of Heinisch and Whidden are
based on impermissible hindsight (App. Br. 15). We are not persuaded for
the reasons discussed above in connection with claim 1.

Claim 8
The Examiner finds that Heinisch, Whidden, Kurachi, and Parker
collectively teach all the limitations of claim 8 (Ans. 8-9). Appellants do not
present new arguments with respect to claim 8. Rather, Appellants state that
claim 8 depends from claim 17 and repeat that: (a) Heinisch and Whidden
fail to teach each and every element of claim 1; (b) Whidden teaches away
from the claimed invention; and (c) the combination of Heinisch and
Whidden are based on impermissible hindsight (App. Br. 15). We are not
persuaded for the reasons discussed above in connection with claim 1.

7 More accurately, claim 8 depends directly from claim 7 and indirectly from
claim 1.
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Claim 21
The Examiner finds that Heinisch, Whidden, Parker, and Kurachi
collectively teach all the limitations of claim 21 (Ans. 9-10). Appellants do
not present new arguments with respect to claim 21. Rather, Appellants
state that claim 21 depends from claim 16 and repeat that: (a) Heinisch and
Whidden fail to teach each and every element of claim 16; (b) Whidden
teaches away from the claimed invention; and (c) the combination of
Heinisch and Whidden are based on impermissible hindsight (App. Br. 15-
16). We are not persuaded for the reasons discussed above in connection
with claim 16.

CONCLUSIONS
(1) Under § 103, Appellants have not shown that the Examiner erred
in finding Heinisch and Whidden collectively teach the recited comparator
that controls the switch to provide a low impedance path or a high
impedance path between the switch’s output terminals depending on the
trigger signal’s voltage level in rejecting claims 1-3, 5, 6, 16, 17, 19, and 20.
(2) Appellants have not shown that Whidden’s discussion related to an
undervoltage protection circuit teaches away from substituting Whidden’s
comparator with Heinisch’s trigger circuit.
(3) Under § 103, Appellants have not shown that the Examiner erred
in finding: (a) Heinisch, Whidden, and Parker collectively teach the
limitations of claims 4 and 18; (b) Heinisch, Whidden, and Kurachi
collectively teach the limitations of claim 7; (c) Heinisch, Whidden,
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Kurachi, and Parker collectively teach the limitations of claim 8; and (d)
Heinisch, Whidden, Parker, and Kurachi collectively teach the limitations of
claim 21.

DECISION
We have sustained the Examiner's rejection of claims 1-8 and 16-21.
Accordingly, the Examiner’s rejection of claims 1-8 and 16-21 is affirmed.
No period for taking any subsequent action in connection with this
appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).

AFFIRMED

pgc

STEFAN V. CHMIELEWSKI
DELPHI TECHNOLOGIES, INC.
Legal Staff, Mail Code: 480-410-202
P.O. Box 5052
Troy, MI 48007-5052