Ex Parte Liu

Patent Trial and Appeal Board

Jun 30, 2016

11924522 (P.T.A.B. Jun. 30, 2016)

United States Patent and Trademark Office
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O.Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
11/924,522 10/25/2007 Xinqiao Liu BAEP-1718 1394
22500 7590 06/30/2016
RAF SYSTRMS
EXAMINER
PO BOX 868 MIYOSHI, JESSE Y
NHQ1-719
NASHUA, NH 03061-0868 ART UNIT PAPER NUMBER
2896
MAIL DATE DELIVERY MODE
06/30/2016 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte XINQIAO LIU
Appeal 2014-001917
Application 11/924,522
Technology Center 2800
Before ADRIENE LEPIANE HANLON, CATHERINE Q. TIMM, and
JAMES C. HOUSEL, Administrative Patent Judges.
TIMM, Administrative Patent Judge.
DECISION ON APPEAL1
1 In our opinion below, we refer to the Specification filed October 25, 2007
(Spec.), Non-Final Office Action filed May 14, 2013 (Non-Final), the
Appeal Brief filed August 7, 2013 (Appeal Br.), the Examiner’s Answer
filed August 29, 2013 (Ans.), and the Reply Brief filed October 21, 2013
(Reply Br.).
Appeal 2014-001917
Application 11/924,522
STATEMENT OF CASE
Appellant2 appeals the Examiner’s decision to reject claims 1, 8, 10,
and 11 under 35 U.S.C. § 103(a) as obvious over Scheffer3 in view of
Mann.4 We have jurisdiction under 35 U.S.C. §§ 6(b) and 134(a).
We AFFIRM.
The claims are directed to an imaging array. See, e.g., claim 1.
The imaging array is used in a sensor that is placed in a patient’s
mouth to record the x-ray image of the patient’s teeth. Spec. 1:5—21. The
sensors typically include a scintillation material used to convert the x-rays to
visible light and a solid-state imaging array that detects the light and forms
an image. Spec. 1:15—16. But x-rays can also generate unwanted electrons
that create background noise in the image. Spec. 4:7—8, 7:13—28.
Appellant’s invention is directed to an imaging array that reduces the
background noise. Spec. 4:7—8, 7:25—28. Figures 6 and 7 illustrate two
embodiments of the imaging array. Figure 6 is reproduced below:
2 Appellant identifies the real party of interest as BAE Systems Imaging
Solutions, Inc. Appeal Br. 1.
3 Scheffer et al., US 7,151,287 Bl, issued Dec. 19, 2006.
4 Mann, US 6,617,562 Bl, issued Sept. 9, 2003.
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Application 11/924,522
51 52
A A80 /------ -------\ f------- “A
\
53
f
In the embodiment of Figure 6, a P-type epitaxial layer 82 is grown on
N-type substrate 81 and the various transistors (51, 52) and photodiodes (53)
are fabricated using known techniques. Spec. 7:28—33. Additionally, the
structure includes an electrode 85 on the back surface of the substrate 81.
Spec. 7:33.
In operation, as in the case in the prior art, implant 61 is depleted of
electrons such that free electrons generated by light in implant 61 or in the
area immediately surrounding implant 61 (shown as depletion area 83) are
accumulated in implant 61. Spec. 7:4—11. Appellant uses the additional
electrode 85 to bias substrate 81 (Vbias), thereby creating a second depletion
region 84 at the boundary of substrate 81 and layer 82. Spec. 7:33—8:17.
Second depletion region 84 sweeps in electrons generated in substrate 81, or
in the region of layer 82 near depletion region 84, and prevents these
electrons, the vast majority of which are x-ray generated, from reaching
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Appeal 2014-001917
Application 11/924,522
photodiode 53. Id. When it is time to reset the photodiodes, Vbias is
increased so that second depletion region 84 grows and joins depletion
region 83, which allows any electrons accumulated in photodiode 53 to be
removed and the photodiodes reset. Spec. 8:19—21.
Because the embodiment of Figure 6 uses an N-type substrate and
requires a contact electrode 85 on the backside of the substrate, Appellant
has developed an alternative embodiment that can be fabricated using
standard CMOS processes. Spec. 9:1—6. This alternative is shown in Figure
7. Figure 7 is reproduced below:
Figure 7 is a cross-sectional view of a portion of another image sensor
93
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Application 11/924,522
The image array of Figure 7 operates in a similar manner to the image
array of Figure 6, but the Figure 7 image array includes an N-type epitaxial
layer 92 between a P-type substrate 91 and a P-type epitaxial layer 93 as
well as a N-type implant contact 94 for applying a bias potential to buried N-
type epitaxial layer 92. Spec. 9:8—18. In a similar manner to the
embodiment of Figure 6, by adjusting the potential (Vbias) on buried layer 92,
a buried depletion layer 96 is formed that traps electrons generated by x-ray
interactions in substrate 91 or in epitaxial layer 93 between layer 92 and
depletion region 83. Id. When Vbias is set such that the depletion region 96
is connected to depletion region 83, the imaging array is effectively held in a
reset state. Spec. 9:20—33.
Claim 1, with reference numerals from Figures 6 and 7, is illustrative
of the claimed invention:
1. An imaging array comprising:
a semiconductor substrate [Fig. 6 (81); Fig. 7 (91)];
an epitaxial layer of semiconductor material [Fig. 6 (82;
Fig. 7 (93)] having a top surface and a bottom surface, said
epitaxial layer being deposited on said semiconductor substrate
such that said bottom surface is adjacent to said semiconductor
substrate;[5]
a plurality of photodiodes [Fig. 6 (53); Fig. 7 (not
labeled)] formed in said epitaxial layer adjacent to said top
surface of said epitaxial layer, each photodiode being
5 The embodiment of Figure 7 requires an epitaxial layer 92 under epitaxial
layer 93. We interpret “deposited on” and “adjacent to” as not requiring
direct contact between the epitaxial layer and the substrate and as allowing
the intervening epitaxial layer 93 of the embodiment of Figure 7. Such an
interpretation is consistent with the broadest reasonable interpretation
consistent with the Specification.
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Appeal 2014-001917
Application 11/924,522
characterized by a photodiode depletion region [Figs. 6 and 7
(83)];
a variable depletion region [Fig. 6 (84); Fig. 7 (96)]
underlying said photodiodes and separated from said top
surface of said epitaxial layer by an amount that depends on a
bias potential; and
a circuit for generating said bias potential, said circuit
providing a first bias potential at which said variable depletion
region is separated from said photodiode depletion regions and
a second bias potential at which said variable depletion region
connects to said photodiode depletion regions such that
electrons generated in said photodiodes are removed from said
photodiodes through said variable depletion region.
Claims Appendix, Appeal Br. 9.
Although claim 1 requires a circuit for generating a bias potential that
functions to create the variable depletion region (second depletion region
disclosed in the Specification), both the claim and the Specification mainly
discuss ways to manipulate the bias potential and not the structure of any
particular circuit. Spec. 8:19—32, 9:20-10:10. Although Figure 6 shows
Vbias as applied to the back surface electrode 85 and Figure 7 shows Vbias
applied through a line connected to contact 94 to epitaxial N-type layer 92,
claim 1 does not explicitly require either the back surface electrode 85 of
Figure 6 or the contact 94 and epitaxial N-type layer 92 of Figure 7.
OPINION
Appellant focuses the arguments on the rejection of claims 1 and 10.
We select these claims as representative for deciding the issues on appeal.
Claim 1
There is no dispute that Scheffer discloses an imaging array, shown in
Figure 5, including a substrate 540, an epitaxial layer 520, photodiodes 552
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Application 11/924,522
with depletion regions 532, a second depletion region 533 underlying the
photodiodes, and a circuit connected to electrode 526 that can forward bias
deep N-well 531 to drain away parasitic electrons. Compare Non-Final 3,
Ans. 3^4 with Appeal Br. 4—6; Reply Br. 2—3.
Figure 5 of Scheffer is reproduced below:
500
Figure 5 schematically shows an embodiment of Scheffer’s x-ray imager
There is further no dispute that Scheffer’s circuit for generating the
bias potential provides the first bias potential at which said depletion region
533 is separated from said photodiode depletion regions 532, but does not
provide a second bias potential at which the variable depletion region 533
connects to the photodiode depletion regions 532. Non-Final 4. It is the
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Application 11/924,522
Examiner’s position that operating the circuit in the manner of claim 1
would have been obvious in view of the teachings of Mann.
Mann resets a photodetector by applying a high reverse bias to a reset
node that is in close proximity to the photodiode junction. Mann, col. 1,11.
61—67. As the bias increases, the depletion regions of the reset junction and
the photodiode junction merge to establish a common potential. Id. Mann’s
Figure 5 shows a reset node 502 that is implanted to have a polarity opposite
the polarity of substrate 504. Mann, col. 4,11. 17—29. For instance, the
substrate 504 may be P-type doped (like Scheffer’s substrate 540) while the
reset node 502 and the photo-detector nodes are N-type doped (like
Scheffer’s deep N-well 531 and photodiode region 528). Figure 6 shows the
discharge path 602 that results when the reset voltage is increased to cause
the depletion region 606 around the reset node 502 to merge with depletion
region 512 around photo-detector node 506. Mann, col. 4, 60-col. 5,1. 10.
Figure 7 shows an embodiment in which the reset node is formed into reset
strip 702 in lieu of reset node 402 of Figures 5 and 6. Reset strip 702, like
Scheffer’s deep N-well, resides underneath the photo-detector nodes 710.
Mann, col. 5,1. 11—col. 6,1. 4.
Scheffer’s deep N-well is an implanted region with a depletion region
like Mann’s reset node, and given the teachings of Mann, it follows that, as
found by the Examiner, those of ordinary skill in the art would have
recognized that the teachings could be combined so that applying a reset
voltage as taught by Mann would cause the merging of the depletion regions
532 and 533 of Scheffer in the manner taught by Mann.
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Application 11/924,522
Appellant’s contention that substantial modifications would be
required to modify Scheffer’s imaging array6 are not persuasive given the
above facts and the Examiner’s rebuttal in the Answer.7 “A person of
ordinary skill is also a person of ordinary creativity, not an automaton.”
KSRInt'l Co. v. Teleflex Inc., 550 U.S. 398, 421 (2007). There is no
persuasive evidence that any required modifications, such as selecting a
voltage source able to apply the required reset potential taught by Mann or
implanting the dopants in the N++ region 528 and deep N-well 531 such that
they have the correct spacing to allow the reset, are outside the ordinary skill
of the ordinary artisan.
Nor can we say that Appellant has persuasively supported the
argument8 that the Examiner’s finding of a reason to apply Mann’s reset
voltage teaching to Scheffer to allow the discharge of accumulated charge on
the photo-detector9 was in error. Mann expressly teaches that the merging of
the depletion regions allows the accumulated charge on the photo-detector to
be released. Mann, col. 5,11. 6—10. Scheffer indicates that such a reset is
necessary, but does not provide the details of how to accomplish this reset of
the photodiodes. Scheffer, col. 4,11. 62—64. Under the circumstances, the
ordinary artisan would have sought out teachings of how to reset the photo­
detector diodes. Mann provides such a teaching. “The combination of
familiar elements according to known methods is likely to be obvious when
it does no more than yield predictable results.” KSR, 550 U.S. at 416.
6 Appeal Br. 5; Reply Br. 2—3.
7 Ans. 3—7.
8 Appeal Br. 5—6.
9 Non-Final 4.
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Application 11/924,522
Appellant has not persuaded us of a reversible error in the Examiner’s
rejection of claim 1.
Claim 10
Claim 10 depends from claim 8. Claim 8 depends from claim 1.
Claim 8 further requires the imaging array include “a detector that detects a
current flowing to or from said variable depletion region.” Claim 10
requires that said bias circuit switch between said first bias potential and said
second bias potential in response to changes in said detected current.
There is no dispute that Scheffer’s image array includes a detector
meeting the requirements of claim 8 as found by the Examiner. Non-Final
4; Scheffer, col. 5,11. 59—61 (measuring circuit that may be coupled to the
metal contact 553 to measure the amount of parasitic electrons and make
adjustments to the x-ray source accordingly.). Appellant does not argue
claim 8 separately.
The Examiner determines that the switching requirement of claim 10
is a matter of intended use that does not patentably distinguish the imaging
array of the claim from that suggested by the combination of Scheffer and
Mann. Non-Final 4—5; Ans. 7—8.
Appellant contends that the limitation of claim 10 is a structural
limitation on the bias circuit, and the Examiner has not pointed to any
teaching of such a structural limitation in either Scheffer or Mann. Appeal
Br. 7.
Appellant does not identify any specific structures required by claim
10 that differ from the structures taught or suggested by Scheffer or the
combination of Scheffer and Mann. Appeal Br. 6—7; Reply Br. 3. Claim 10
recites a switching function for the bias circuit; not a structural element of
the bias circuit. The structural implications of the function are not evident
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Application 11/924,522
and recourse to the Specification does not provide guidance: The
Specification does not identify a structure for the switching function. Spec.
8-10.
It has long been held that “apparatus claims cover what a device is,
not what a device does.” Hewlett-Packard Co. v. Bausch & Lomb Inci5 909
F.2d 1464, 1468 (Fed. Cir. 1990). An inventor of a structure (machine or
article of manufacture) is entitled to benefit from all of its uses, even those
not described, Roberts v. Ryer, 91 U.S. 150, 157 (1875), and conversely,
patentability of the structure cannot turn on the use or function of the
structure. In re Michlin, 256 F.2d 317, 320 (CCPA 1958) (“It is well settled
that patentability of apparatus claims must depend upon structural
limitations and not upon statements of function.”). Therefore, the courts
have devised a test: Structures such as machines and articles of manufacture
must be distinguished from the prior art on the basis of structure, and where
there is reason to believe that the structure of the prior art is inherently
capable of performing the claimed function, the burden shifts to the
applicant to show that the claimed function patentably distinguishes the
claimed structure from the prior art structure. See In re Schreiber, 128 F.3d
1473, 1478 (Fed. Cir. 1997); In re Hallman, 655 F.2d 212, 215 (CCPA
1981). Given that the structural difference is not clear, we cannot say that
Appellant has identified a reversible error in the Examiner’s findings and
conclusion of obviousness on this basis.
Moreover, the Examiner provides an obviousness analysis not
adequately addressed by Appellant. The Examiner finds that Scheffer
discloses a parasitic readout circuit 553 having a measuring circuit for
measuring the amount of parasitic electrons 528 that are drained from
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Application 11/924,522
depletion region 533 and adjusting the x-ray source accordingly. Ans. 8;
Scheffer, col. 5,11. 51—63. The Examiner reasons that:
Claim 10 requires said bias circuit switches between the first
bias potential and the second bias potential in response to
changes in detected current. Since this claim is very broad in
that any change in the detected current incites a switch in bias,
it would have been obvious to one of ordinary skill in the art at
the time of the invention that when a spike in parasitic electrons
is detected, the X-ray is on, and an image is to be captured.
Since the duration an X-ray is on should be minimized, it would
be [sic, have been] obvious that a quick reset operation should
be performed and an image capture operation quickly
performed thereafter. This would require switching between the
two potentials.
Ans. 8.
In response, Appellant argues that the Examiner is basically arguing
that the device suggested by the Examiner is capable of the claim
limitations, and that such an argument is not sufficient to sustain a rejection
for obviousness. Reply Br. 3. But the Examiner’s conclusion is that the
switching operation of claim 10 would have been suggested to the ordinary
artisan by the combination of Scheffer and Mann. The Examiner is not
basing the obviousness analysis solely on a capability of the circuit.
Appellant does not point out any error in the obviousness analysis presented
in the Answer. Thus, Appellant has not identified a reversible error in the
obviousness analysis.
CONCLUSION
We sustain the Examiner’s rejection.
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Application 11/924,522
DECISION
The Examiner’s decision is affirmed.
TIME PERIOD FOR RESPONSE
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).
AFFIRMED
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