Ex Parte Heldberg

Board of Patent Appeals and Interferences

Dec 19, 2007

10193226 (B.P.A.I. Dec. 19, 2007)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte CARSTEN HELDBERG
____________

Appeal 2007-2747
Application 10/193,226
Technology Center 2800
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Decided: December 19, 2007
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Before KENNETH W. HAIRSTON, MAHSHID D. SAADAT, and
CARLA M. KRIVAK, Administrative Patent Judges.

KRIVAK, Administrative Patent Judge.

DECISION ON APPEAL
Appellant appeals under 35 U.S.C. § 134 (2002) from a final rejection
of claims 1-4, 8-11, and 13-201. We have jurisdiction under 35 U.S.C. § 6(b)
(2002).

(Footnote continued on the next page)
1 After the Pre-Appeal Brief Conference, the Examiner canceled claims 5
and 6, and objected to claims 7 and 12. However, with respect to claims 7
and 12, we are aware of references that appear to recite a force detector
mounted in a housing sealed by a membrane, and fitted with a pin projecting
Appeal 2007-2747
Application 10/193,226

We affirm.
STATEMENT OF CASE
Appellant’s claimed invention is an apparatus for continuously
measuring the liquid level in a container. The apparatus includes a buoyant
body located in a container and biased in the direction of buoyancy, a force
detector affixed to the container, and an analyzer processing an electrical
signal from the force detector.
Independent claims 1, 8, and 15, and dependent claim 4, reproduced
below, are representative of the subject matter on appeal.
1. Apparatus for detecting any arbitrary changes of a liquid level
within a container, said apparatus comprising:
a buoyant body in the container,
a force detector affixed to a container wall,
a support at an opposite container wall, where the buoyant body
is mounted in a substantially motionless manner while being
permanently biased in the direction of buoyancy toward the force
detector from the support, and
an analyzer processing an electrical signal from the force
detector.

into the container and acting on a force detector. See, for example, US
Patent 5,338,429. Although not in the same field as the present invention it
addresses the same problem. See In re Clay 966 F.2d 656 (Fed. Cir. 1992).
Also See In re Translogic Technology, Inc. No. 2006-1192, 2007 WL
2965979, at * (Fed. Cir. 2007) "We have noted that evidence of a
suggestion, teaching, or motivation to combine may flow from the prior art
references themselves, the knowledge of one of ordinary skill in the art, or,
in some cases, from the nature of the problem to be solved [citing In re
Dembiczak, 175 F.3d 994, 999 (Fed. Cir. 1999)] . . . In the context of KSR,
the [reference] teachings and its obvious variants were relevant prior art,
even if that patent did address a different problem.”
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Application 10/193,226

4. Apparatus as claimed in claim 1, wherein the geometry of the
buoyant body matches the container inside space so that the buoyancy
is approximately proportional to the liquid's volume.

8. An apparatus for measuring a level of a liquid within a
container having a top wall and a bottom wall, said apparatus
comprising:
a buoyant body positioned in the container and having, in a
longitudinal direction thereof, an upper end and a lower end;
a force detector affixed to the top wall of the container and
linked to the upper end of said buoyant body, said force detector being
configured to output an electrical signal indicative of the force applied
thereto; and
a support connecting the lower end of said buoyant body to the
bottom wall of the container, said support comprising an upwardly
urging spring that permanently biases, by a biasing force, said buoyant
body towards said force detector regardless of the liquid level in the
container;
wherein said buoyant body is mounted substantially
motionlessly, in at least said longitudinal direction, between said force
detector and said support.

15. A fuel tank for a motor vehicle, said fuel tank comprising an
apparatus for measuring a fuel level within said tank, said apparatus
comprising:
a buoyant body positioned in said tank and having, in a
longitudinal direction thereof, an upper end and a lower end;
a force detector affixed to a top wall of said tank and linked to
the upper end of said buoyant body, said force detector being
configured to output an electrical signal indicative of the force applied
thereto; and
a support connecting the lower end of said buoyant body to a
bottom wall of said tank, said support comprising an upwardly urging
spring that biases said buoyant body towards said force detector;
wherein said buoyant body is maintained substantially
motionlessly, in at least said longitudinal direction, between said force
detector and said support regardless of the fuel level.

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Application 10/193,226

REFERENCES
DeGiers US 1,590,287 June 29, 1926
Wohrl US 4,244,218 Jan. 13, 1981
Crawford US 5,132,923 July 21, 1992

The Examiner rejected claims 1-3, 8-11, 13-15, and 17-20 under 35
USC § 103(a) based upon the teachings of DeGiers and Crawford. The
Examiner rejected claims 4 and 16 under 35 USC § 103(a) based upon the
teachings of DeGiers in view of Crawford, and further in view of Wohrl.
Appellant contends that the applied references neither teach nor
suggest to one of ordinary skill in the art replacing a displacement sensor
(which acts mechanically) with a force or load sensor (Br. 23; Reply Br. 1)
which outputs an electrical signal, in an apparatus for detecting arbitrary
changes in liquid level within a container.

ISSUES
The issue before us is did the Examiner err in finding that combining
the strain-gauge type force sensor outputting electrical signals and analyzer
of Crawford with the liquid level detector apparatus of DeGiers would have
rendered the subject matter of claims 1-3, 8-11, 13- 15, and 17-20 obvious
under 35 § 103(a) to one of ordinary skill in the art at the time of the
invention? Further, did the Examiner err in finding that combining DeGiers
and Crawford along with the geometric teachings of Wohrl would have
rendered the subject matter of the claims 4 and 16 obvious?

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Application 10/193,226

FINDINGS OF FACT
The following findings of fact are supported by a preponderance of
the evidence.
1. Appellant invented an apparatus for continuously measuring the
liquid level in a container including a buoyant body mounted in a
substantially motionless manner, buoyancy being substantially in the
direction of a force detector and being converted into an electrical signal
corresponding to the liquid level (Specification 1: 18-23).
2. Buoyancy is directly proportional to the liquid level
(Specification 1: 25).
3. Claim 1 of Appellant’s application recites a force detector and
an analyzer for processing an electrical signal from the force detector and
claims 8 and 15 recite a force detector being configured to output an
electrical signal indicative of the force applied thereto.
4. Appellant’s force detector can be a piezoelectric-detector or
strain gauge (Specification 2: 7-8).
5. DeGiers teaches a buoyant body in a container, a force detector,
a support that keeps the buoyant body mounted in a substantially motionless
manner (p. 1, l. 108 through p. 2, ll. 2 and 128) indicates “operative
movement is very small”) and biases the float upward, and an indicating
device indicating the quantity of liquid in a container (p. 1, ll. 1-5).
6. The DeGiers indicating device processes a signal from the force
detector into a pressure reading indicating the level of fluid in the container.
Any indicating device may be used (p. 2, ll. 47-50).
7. Pressure is defined as force per unit area.
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8. DeGiers provides a compensating means such as a spring
located at the bottom of the container, the spring being tensioned (p. 2, ll. 6-
11).
9. Crawford teaches a tank monitoring system which measures the
buoyancy force (col. 2, ll. 58-60) using a strain-gauge type detector (load
cell assembly 96, Figure 4, col. 6, ll. 36-38) to output an electrical signal
indicating the level of liquid in the container.
10. Wohrl teaches that it is known in the art to match the geometry
of a float with that of the container so that the buoyancy is approximately
proportional to the liquid’s volume (col. 1, ll. 46-50; Answer 7-8).
11. Crawford also teaches that the cross-section of the displacer is
varied proportionally to the geometry of the tank (col. 5, ll. 63-64).

PRINCIPLES OF LAW
The Federal Circuit in Leapfrog Enters., Inc. v. Fisher-Price, Inc., 485
F.3d 1157, 1161 (Fed. Cir. 2007) held that “[a]ccommodating a prior art
mechanical device that accomplishes [a desired] goal to modern electronics
would have been reasonably obvious to one of ordinary skill…” In reaching
that conclusion, the Federal Circuit recognized that “[a]n obviousness
determination is not the result of a rigid formula disassociated from the
consideration of the facts of a case. Indeed, the common sense of those
skilled in the art demonstrates why some combinations would have been
obvious where others would not.” Id. at 1161 (citing KSR Int’l Co. v Teleflex
Inc., 127 S.Ct. 1727, 1739 (2007) (“The combination of familiar elements
according to known methods is likely to be obvious when it does no more
than yield predictable results.”). The Federal Circuit relied in part on the fact
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that no evidence was presented showing that the inclusion of a reader in the
combined device was “uniquely challenging or difficult for one of ordinary
skill in the art” or “represented an unobvious step over the prior art.” Id. at
1162 (citing KSR, 127 S.Ct. at 1740-41). The substitution of an electrical
read out for a manual read out is no more than “the simple substitution of
one known element for another or the mere application of a known
technique to a piece of prior art ready for improvement.” KSR, 127 S.Ct. at
1740.
An improvement in the art is obvious if “it is likely the product not of
innovation but of ordinary skill and common sense.” Id. at 1742.
There is a fundamental proposition that obvious variants of prior art
references are themselves part of the public domain. In re Translogic
Technology, 2006-1192 citing KSR Int'l Co., 127 S.Ct. at 1743; Dystar
Textilfarben GmbH & Co. Deutschland KG v. C.H. Patrick Co., 464 F.3d
1356, 1361 (Fed. Cir. 2006); In re Dembiczak, 175 F.3d at 999.
One can not show nonobviousness by attacking references
individually where the rejection is based on a combination of references.
The test for obviousness is not whether the features of a secondary reference
may be bodily incorporated into the structure of the primary reference. Nor
is it that the claimed invention must be expressly suggested in any one or all
of the references. Rather, the test is what the combined teachings of the
references would have suggested to the artisan. In re Keller, 642 F.2d 413,
425 (CCPA 1981).

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ANALYSIS
With respect to independent claims 1, 8, and 15, based upon the
teachings of DeGiers and Crawford, we agree with the Examiner’s rationale
in the rejection that “the concepts on which the two inventions are based, are
exactly the same, and combining teachings from the Crawford reference
with the apparatus of DeGiers would be more than obvious to one of
ordinary skill in the art” (Answer 20). The Examiner’s rationale for
combining the teachings of the references involves common knowledge and
common sense in the art (Leapfrog, 485 F.3d at 1161), and is not the result
of impermissible hindsight as alleged by the Appellant (Reply Br. 4). It is
what the combined teachings would have suggested to one skilled in the art.
Claim 1 teaches a buoyant body that is substantially motionless, a
force detector, and an analyzer for processing an electrical signal from the
force detector. Claim 8 differs from claim 1 only in that the buoyant body is
positioned in a longitudinal direction, is substantially motionless in at least
that direction, the force detector is positioned at the upper end of the buoyant
body, and the support includes an upwardly urging spring. Claim 15 merely
adds that the apparatus is a fuel tank for a motor vehicle and that the buoyant
body is maintained substantially motionless in at least the longitudinal
direction regardless of the fuel level.
DeGiers teaches all the features of claims 1, 8, and 15 except for the
electrical signal. Crawford teaches a buoyancy type level detector having a
strain gauge type force sensor mounted in a housing (Fig. 4) to measure an
electrical signal sent to an analyzer for processing. Adding an electrical
signal output and analyzer in lieu of a mechanical signal indicator as set
forth in DeGiers would have been obvious to the skilled artisan. DeGiers
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issued in 1926 when strain gauges and electrical processors (computers), for
analyzing signals from the strain gauges, were not yet available. Substituting
an electric device for an “old” mechanical device to achieve the same result
is not new. Thus, “[a]ccommodating a prior art mechanical device that
accomplishes [a desired] goal to modern electronics would have been
reasonably obvious to one of ordinary skill …” Leapfrog, 485 F.3d at 1161.
With respect to claim 2, the recitation of a force detector mounted at the
upper wall of the container and the support at the lower wall is taught by
DeGiers (Fig. 1)
The partly hollow buoyant body claimed in claim 3 is taught by
DeGiers (p. 1, ll. 106-107).
Claims 4 and 16 recite that the geometry of the buoyant body matches
the side space of the tank or container so that the buoyancy is approximately
proportional to the volume of the liquid (or fuel) in the container or tank.
Wohrl (col. 1, ll. 45-48) and Crawford (col. 5, ll. 53–55 and 61–64) both
teach this feature. Appellant’s argument that the shape of the float in Wohrl
must take the form of a thin disk if applied to the combination of the
DeGiers and Crawford references (Br. 17, 19, 22) is not persuasive as both
references teach that the cross-sectional area of a body at any fluid level has
a known relationship with the cross-sectional area of the container at the
same fluid level.
The analyzer of claim 9, coupled to receive and process a signal
outputted from the force detector, is obvious as that is the function of an
analyzer.
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Claims 10, 11, 13, 17, 18, and 19 all deal with the biasing force and
gravitational force and how they act on the buoyant body. (DeGiers, p. 2, ll.
106-124). This type of biasing is known.
Claims 14 and 20 teach the analyzer being configured to compensate
for the pre-stressing force. This is merely calibrating the analyzer to
“compensate for the extra [l]oad upon the detector…to obtain accurate
readings.” (Answer 7; DeGiers, p. 2, ll. 6-10). Again, it is known in the art
that if the pre-stressing force was not compensated, the output would not be
accurate.

CONCLUSION
We therefore conclude that the Examiner did not err in rejecting
claims 1-4, 8-11, and 13-20 under 35 U.S.C. § 103(a).

DECISION
The decision of the Examiner rejecting claims 1-4, 8-11, and 13-20 is
affirmed.
No time 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

tdl

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