Ex Parte Sato et al

Board of Patent Appeals and Interferences

Jan 30, 2009

10417149 (B.P.A.I. Jan. 30, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte KENJI SATO,
TOSHIYUKI SATO, TAKAYUKI NAKAYAMA, YOICHIRO SHIMURA,
and KAZUHIKO SHIMA
____________

Appeal 2008-6037
Application 10/417,1491
Technology Center 2800
____________

Decided:2 January 30, 2009
____________

Before CHARLES F. WARREN, TERRY J. OWENS, and
MARK NAGUMO, Administrative Patent Judges.

NAGUMO, Administrative Patent Judge.
DECISION ON APPEAL

1 Application 10/417,149, X-ray Detector, filed 17 April 2003, claiming the
benefit of a Japanese Application filed 23 April 2002. The specification is
referred to as the “149 Specification,” and is cited as “Spec.” The real
parties in interest are listed as Shimadzu Corporation, Shindengen Electric
Manufacturing Co., and Yamanashi Electronics Co., Ltd. (Appellant’s Brief,
filed 5 July 2007 (“Br.”), 2.)
2 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).

Appeal 2008-6037
Application 10/417,149

A. Introduction
Kenji Sato, Toshiyuki Sato, Takayuki Nakayama, Yoichiro Shimura,
and Kazuhiko Shima (“Sato”) timely appeal under 35 U.S.C. § 134(a) from
the final rejection of claims 1, 2, 5-8, and 11-13 . We have jurisdiction
under 35 U.S.C. § 6(a). We REVERSE.
The subject matter on appeal relates to an X-ray detector having, as an
element that generates charge when exposed to X-rays, amorphous selenium
(“a-Se”) doped with an alkali or alkaline-earth metal. The dopants are said
to compensate for structure defects in the a-Se and to enable the detector to
be free from deterioration of sensitivity.
Representative Claim 1 is reproduced from the Claims Appendix to
the Principal Brief on Appeal:
Claim 1
An X-ray detector for detecting X rays, comprising:
[a] a semiconductor for generating electric charges
therein upon X-ray incidence;
[b] electrodes formed on opposite sides of said
semiconductor for application of a predetermined bias
voltage;
[c] a first carrier selection layer formed on said
semiconductor at a side of a positive one of said
electrodes, that is at a side of an electrode having a
higher potential, for restricting an injection of holes;
[d] a second carrier selection layer formed on said
semiconductor at a side of a negative one of said
electrodes, that is at a side of an electrode having a lower
potential, for restricting an injection of electrons;
[e] wherein said semiconductor is amorphous selenium
(a-Se) doped with a predetermined quantity of an alkali
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Appeal 2008-6037
Application 10/417,149

metal or alkaline earth metal in a quantity ranging from
0.01 to 10ppm.
(Claims App., Br. 14; bracketed letter labels and indentation added.)
Claim 13 is similar but does not require the second carrier selection
layer.
The Examiner has maintained the following grounds of rejection:3
A. Claims 1, 5, 7, 11, and 13 stand rejected under
35 U.S.C. § 103(a) in view of the combined teachings of
Schiebel4 and Imai.5
B. Claims 2, 6, 8, and 12 stand rejected under 35 U.S.C. § 103(a)
in view of the combined teachings of Schiebel, Imai, and
Brauers.6
Sato contends, inter alia, that the Examiner erred because the applied
references do not teach or suggest a charge generating element [a] that is [e]
amorphous selenium doped with 0.01 to 10 ppm of an alkali metal or
alkaline earth metal.
The Examiner disagrees.
The dispositive issues are: what do limitations [a] and [e] mean; and
does Schiebel or Imai teach or suggest such an amorphous selenium
semiconductor doped with sodium for generating electric charges upon
X-ray incidence?

3 Examiner’s Answer mailed 16 October 2007. (“Ans.”)
4 Ulrich Schiebel et al., X-Ray Image Detector, U.S. Patent 5,396,072
(1995).
5 Shinji Imai, Image Recording Medium and Method of Manufacturing the
Same, U.S. Patent Application Publication US 2001/0025933 A1 (2001).
6 Andreas Brauers and Ulrich Schiebel, X-Ray Image Sensor, U.S. Patent
5,729,021 (1998)
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Appeal 2008-6037
Application 10/417,149

B. Findings of Fact
Findings of fact throughout this Decision are supported by a
preponderance of the evidence of record.
The 149 Specification
1. The 149 Specification describes the X-ray detector by reference to
Figure 1, which is shown below:

{Figure 1 is said to show a diagram of an X-ray detector.}7
2. According to the 149 Specification, the X-ray detector comprises a
thick film 4 of amorphous selenium [“a-Se”] doped in the range of 0.01
to 10 ppm with an alkali metal. (Spec. 8:10-11.)
3. On either side of the a-Se layer 4 are carrier selection layers 2 and 5,
which prevent injection of electrons and holes and electrons, respectively,
when associated electrode 6 is biased positive relative to electrode 1.
(Spec. 8:7-16.)

7 The text in curly braces following the Figures is provided to ensure
compliance with section 508 of the U.S. Rehabilitation Act for publication
of this Decision on the USPTO website pursuant to the Freedom of
Information Act. It is not part of the Decision.
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Appeal 2008-6037
Application 10/417,149

4. The entire structure is carried on insulating substrate 3. (Spec. 8:9.)
5. The 149 Specification teaches that X-rays incident on the amorphous
selenium thick film 4 generate electron-hole pairs near the surface of the
material. (Spec. 5:9-12.)
6. The electrons migrate towards the positively biased electrode 6, which
is preferentially positioned on the side of X-ray incidence. (Spec. 5:5-9
and 12-16.)
7. According to the invention described and claimed in
the 149 Specification, an alkali metal or an alkaline earth metal having a
strong ionization tendency is added to amorphous selenium layer 4 in a
quantity to compensate for structural defects D0. (Spec. 3:24-4:3.)
8. The defects D0 are said to trap electrons that are generated by X-rays
incident on a-Se layer 4, thereby degrading the signals by a mechanism
described at page 4 of the 149 Specification. (Spec. 4.)
9. According to the 149 Specification, the prescribed doping eliminates,
or suppresses by as much as one half, the deterioration in sensitivity of the
detector element on exposure to X-rays. (Spec. 4:17-28.)
10. The amorphous selenium thick film 4 is said to be 1-mm thick in all
X-ray detectors described in the 149 Specification. (Spec. 13:7-9.)
11. The 149 Specification does not appear to describe a preferred
thickness of carrier selection layers 2 and 5.
Schiebel
12. Schiebel describes an X-ray image detector with reference to Figure 4.
(Schiebel 5:6-49.)
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Appeal 2008-6037
Application 10/417,149

13. Schiebel Figure 4 is shown below:

{Schiebel Figure 4 is said to show an X-ray detector}
14. The features of principal interest are:
(a) photoconductor layer 32, which is said to be a layer of amorphous
selenium with 0.1 to 1% arsenic, to detect8 the X-rays (Schiebel 5:37-42);
(b) electron-blocking, hole-conductive layer 31, which may be
a 1 to 5 μm thick layer of selenium doped with 20 to 200 ppm chlorine (id.
at 5:29-37);
(c) hole-blocking, electron-conductive layer 33, which may be
a 0.5 to 2 μm thick layer of selenium doped with from 20 to 200 ppm alkali
metal; and

8 According to Schiebel, the X-ray detecting a-Se layer 32 “must have a
thickness of between 200 and 800 μm so as to achieve adequate absorption
of the X-ray quanta occurring during a medical examination.” (Schiebel
5:39-42.)
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Appeal 2008-6037
Application 10/417,149

(d) cover (bias) electrode 4 and collecting electrode 14 and (id. at 5:26
and at 5:24; and at 5:53-54).
Imai
15. Imai describes an image recording device that records a latent image
from an X-ray exposure (e.g., of the lungs of a patient) in a “recording
photoconductive layer,” wherein the latent image is “read out” by exposing
an adjacent “reading photoconductive layer” to blue light, which induces a
signal proportional to the charge built up in the first conductive layer by the
X-ray exposure. (See, e.g., Imai 3:[0026].)
16. The structure of the Imai recording and reading device is shown in
Figure 1B, which is reproduced below:

{Imai Figure 1B is said to show an image recording device}
17. In the image recording device, an X-ray “permeable” electrode 1 lies
on a-Se recording layer 2, which is separated by insulating charge transfer
layer 3 from a-Se reading layer 4, which is next to blue-light (< 550 nm)
“permeable” electrode 5, which in turn is next to blue-light permeable
substrate 8. (Imai 8:[0108].
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Appeal 2008-6037
Application 10/417,149

18. According to Imai, the recording and reading photoconductive layers
preferably comprise amorphous selenium, a-Se, doped with arsenic [atomic
symbol “As”] as a bulk- or interfacial-crystallization suppressing material.
(Imai 3:[0026]-[0027].)
19. Imai teaches that the thickness of the recording photoconductive layer
is preferably about 50 to 1000 μm (Imai 3:[0028]), more preferably 700
to 1000 μm. (E.g, id. at 3:[0037], 4:[0043] and [0050], 11:[0138].)
20. In contrast, according to Imai, the thickness of the reading
photoconductive layer is preferably 0.05 to 0.5 μm. (E.g., Imai 3:[0028],
5:[0051], 10:[0126].)
21. Imai teaches that the recording photoconductive layer can be
advantageously doped with chlorine (atomic symbol “Cl”) at 20 to 250 ppm.
(E.g., Imai 3:[0033], [0036], 5[0039], 10:[0135].)
22. Similarly, Imai teaches that the reading photoconductive layer can be
advantageously doped with Cl at 1 to 1000 ppm. (E.g., Imai 6:[0064],
7:[0082], 15[0187].)
23. However, Imai also teaches that the performance of the reading
photoconductive layer can also be improved: “[p]ositive hole traps can be
increased by doping with Na [sodium] in an amount of 1 to 1000 ppm in
place of As.” (E.g., Imai 6:[0064], [0074], 7:[0081]-[0082],
15:[0186]-[[0187].]
24. Notably, Imai does not appear to teach that positive hole doping of the
recording photoconductive layer with Na would be advantageous.
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Appeal 2008-6037
Application 10/417,149

C. Discussion
As the Appellant, Sato bears the procedural burden of showing
harmful error in the Examiner’s rejections. See, e.g., In re Kahn, 441 F.3d
977, 985-86 (Fed. Cir. 2006) (“On appeal to the Board, an applicant can
overcome a rejection [under § 103] by showing insufficient evidence of
prima facie obviousness”) (citation and internal quote omitted).
A prima facie case of obviousness is not made if the references fail to
disclose or suggest a limitation required by the claimed subject matter. See,
e.g., In re Zurko, 258 F.3d 1379, 1384–85 (Fed. Cir. 2001).
In the present case, limitation [e] requires that the semiconductor [a]
that generates electric charges upon X-ray incidence “is amorphous selenium
(a-Se) doped with a predetermined quantity of an alkali metal or alkaline
earth metal in a quantity ranging from 0.01 to 10ppm” (emphasis added).
The 149 Specification, Schiebel, and Imai all teach that an X-ray recording
layer of a-Se is preferably thick, on the order of 1 mm (1000 μm). Both
Schiebel and Imai teach that amorphous selenium is maintained in an
amorphous state by the presence of arsenic. We conclude that “amorphous
selenium,” as used in the claims on appeal, encompasses amorphous
selenium that contains arsenic as an anti-crystallization agent, as taught by
Schiebel and Imai. There appears to be no contrary definition in
the 149 Specification.
Imai describes a-Se films doped with 1 to 1000 ppm Na, but all such
films are reading photoconductive layers. According to Imai, reading
photoconductive layers are thin, on the order of 0.05 to 0.5 μm. In light of
the teachings of the 149 Specification, Schiebel, and Imai regarding the
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Appeal 2008-6037
Application 10/417,149

preferred 1000 μm thickness of recording photoconductive a-Se layers,
Sato’s criticism that the Examiner has not shown that the prior art relied on
teaches that Na-doped layers would be useful as recording photoconductors
(Br. 10-11) is well-supported.
The Examiner has failed to identify disclosures in Imai or in Schiebel
that would have taught or suggested doping the X-ray recording
photoconductive a-Se layer in either reference with sodium at 0.01
to 10 ppm. The disclosures of Brauers are not relevant to this issue because
the Examiner has relied on Brauers solely for additional limitations recited
in dependent claims.
As neither Schiebel nor Imai teach or suggest a semiconductor for
generating electric charges upon X-ray exposure that is amorphous selenium
doped with alkali metals or alkaline earth metals, we REVERSE the
rejections of record.
D. Order
We REVERSE the rejection of claims 1, 5, 7, 11, and 13 under
35 U.S.C. § 103(a) in view of the combined teachings of Schiebel and Imai.
We REVERSE the rejection of claims 2, 6, 8, and 12 under
35 U.S.C. § 103(a) in view of the combined teachings of Schiebel, Imai, and
Brauers.
REVERSED

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Appeal 2008-6037
Application 10/417,149

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