Ex parte Kumagai et al.

Board of Patent Appeals and Interferences

Apr 13, 1998

08001199 (B.P.A.I. Apr. 13, 1998)

Application for patent filed January 7, 1993. According to appellants, this application is1
a continuation-in-part of Application 07/854,085, filed March 19, 1992, now U.S. Patent No.
5,303,110, granted April 14, 1994.
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law journal and (2) is not binding precedent of the Board.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 NAOKI KUMAGAI
and KATSUNORI UENO
_____________
Appeal No. 95-0648
Application 08/001,1991
______________
ON BRIEF
_______________
Before URYNOWICZ, HAIRSTON and TORCZON, Administrative Patent Judges.
URYNOWICZ, Administrative Patent Judge.
DECISION ON APPEAL
This appeal is from the final rejection of claims 13-19 and 21-23.
The invention pertains to a short protective circuit. Claim 13, the only independent claim,
is illustrative and reads as follows:
Appeal No. 95-0648
Application 08/001,199
2
13. A short protective circuit comprising:
a control terminal;
a first switching element having a control electrode, a first electrode and a second
electrode, said first switching element being driven by a signal applied from the control terminal to
the control electrode;
a second switching element for current detection having a control electrode, a first
electrode and a second electrode, the control electrode and the first electrode of the second
switching element being respectively connected to the control electrode and the first electrode of
the first switching element, the second electrode of the second switching element being connected
to the second electrode of the first switching element through a current detecting resistor;
a branch circuit having a discharge switching element, said branch circuit connected to a
circuit connection between the control terminal and the control electrode of the first switching
element;
means for reducing a drive signal of the first switching element by activating the discharge
switching element when an excessive current flows through a current detecting resistor, said
discharge switching element maintaining the reduced drive signal when the excessive current
flowing through the first switching element is suppressed as the drive signal decreases; and
means for deactivating the discharge switching element when a signal applied to the
control terminal becomes zero or opposite in polarity from the drive signal after the drive signal is
reduced.
The references relied upon by the examiner are:
Okado et al. (Okado) 4,719,531 Jan. 12, 1988
Mihara et al. (Mihara) 4,893,158 Jan. 09, 1990
Kumagai 5,303,110 Apr. 12, 1994
(filed Mar. 19, 1992)
Appeal No. 95-0648
Application 08/001,199
3
Appellants’ acknowledged prior art shown in Figs. 7 and 8 and described at pages 1-7 of their
specification.
The appealed claims stand rejected under 35 U.S.C. § 103 as being unpatentable over the
acknowledged prior art in view of Okado and Mihara.
The appealed claims also stand rejected under the judicially created doctrine of
obviousness type double patenting as being unpatentable over claims 1-12 of Kumagai in view of
Okado and Mihara.
The respective positions of the examiner and the appellants with regard to the propriety of
the rejection under 35 U.S.C. § 103 are set forth in the final rejection (Paper No. 8), the
examiner's answer (Paper No. 13), a supplemental examiner’s answer (Paper No.15) and a second
supplemental examiner’s answer (Paper No. 19) and the appellants’ second substitute brief on
appeal (Paper No. 18). The respective positions of the examiner and the appellants with regard to
the obviousness double patenting rejection are set forth in the supplemental examiner’s answer
and appellants’ second substitute brief on appeal.
Appellant's Invention
Appellants’ device is illustrated in Fig. 9. It comprises a short protective circuit having a
control terminal G, a first transistor 10, and a second transistor 20. The control terminal is
connected to the control electrodes of the first and second transistors; the first electrode of the
first transistor is connected to the first electrode of the second transistor; and the second electrode
Appeal No. 95-0648
Application 08/001,199
The “means for reducing”, the penultimate limitation and only other limitation which might possibly be2
considered as not taught by the Fig. 8 prior art circuit, is met by resistors 30 and 65 which lower the
voltage applied to gate 105 of the first switching element 10 (appellants’ specification at page 4, lines
18-26).
4
of the first transistor is connected to the second electrode of the second transistor through a
current detecting resistor 40. A branch circuit having a discharge transistor 50 is connected
between the control and second electrodes of the first transistor.
When an excessive current flows through the current detecting resistor 40 due to a short
in the load circuit of the first transistor, diode 65 reduces a drive signal of the first transistor 10 by
activating transistor 50. The reduced drive signal is maintained as the excessive current flowing
through transistor 10 is suppressed to protect the transistor. Diode 42 deactivates discharge
transistor 50 when a signal applied to the control terminal G becomes zero or opposite in polarity.
The Rejection under 35 U.S.C. §103 over the
Admitted Prior Art, Okado and Mihara
After consideration of the positions and arguments presented by both the examiner and the
appellants, we have concluded that this rejection should not be sustained.
With respect to claim 13, the sole independent claim, all of the claim limitations, except
for the last limitation, are met by the admitted prior art illustrated in appellants’ Fig. 8 . However,2
neither Okado nor Mihara makes up for the deficiency of the admitted prior art by teaching the
last limitation of claim 13 which reads,
Appeal No. 95-0648
Application 08/001,199
5
means for deactivating the discharge switching element when a signal applied to
the control terminal becomes zero or opposite in polarity from the drive signal
after the drive signal is reduced.
The examiner’s position in the supplemental examiner’s answer (Paper No. 19) is that this
limitation is met by Fig. 7 of Okado and that MOSFET 30 short circuits and deactivates the
switching element gate transistor 26 during a negative control signal. Reference is made by the
examiner to column 7, lines 45+, of Okado.
We disagree with this position. MOSFET 30 does not short circuit the gate of switching
element transistor 26 because of the large time constant exhibited by elements 28 and 29. At
column 7, lines 45-54, no reference is made to transistor 26, indicating that it is deactivated as
urged by the examiner. Contrary to the examiner’s position, at column 8, lines 26-35, Okado
teaches that the time constant of resistor 28 and diode 29 is large, such that the on time of
transistor 26 is longer than the oscillatory time of the voltage between the drain and source of the
BIFET transistor 1. This is the same type of operation as disclosed for appellants’ embodiment of
Fig. 5, wherein there is no deactivation of the discharge transistor 50. In that embodiment, diode
65 and resistor 66 correspond to aforementioned diode 29 and resistor 28, and the discharge
transistor 50 of Fig. 5 cannot be deactivated when a signal applied to the control terminal G
becomes zero or opposite in polarity because of the charge retained on the gate of transistor 50
due to the time constant of elements 65 and 66. It is only by the addition of a diode, such as
diode 42 in Fig. 9, that discharge transistor 50 can be deactivated when a signal applied to the
Appeal No. 95-0648
Application 08/001,199
6
control terminal G becomes zero or opposite in polarity. This is illustrated in appellants’ Fig. 10,
waveform (d), at time t . 3
In his answers, the examiner has not indicated how Mihara is applied against claim 13. In
the first office action (Paper No. 4), the examiner relied on the embodiments illustrated in Figs. 29
and 30 of Mihara. Because the examiner has not specifically indicated where in either of these
figures Mihara teaches means for deactivating a discharge switching element as defined in claim
13 and because no such means is apparent in the reference, we will not sustain the rejection to the
extent it relies on Mihara.
Because neither Okado nor Mihara teaches the “means for deactivating” of sole
independent claim 13, a prima facie case of obviousness has not been established and the rejection
is not sustained. Whereas claims 14-19 and 21-23 depend from claim 13, the rejection of these
claims under 35 U.S.C. § 103 over the admitted prior art, Okado and Mihara is not sustained.
The Rejection under Obviousness Type Double Patenting
over Claims 1-12 of Kumagai in View of Okado and Mihara
Whereas we have found that neither Okado nor Mihara teaches the last limitation of
independent claim 13, we will not sustain this rejection.
Appeal No. 95-0648
Application 08/001,199
7
Summary
In summary:
a) The rejection of claims 13-19 and 21-23 under 35 U.S.C. § 103 as being unpatentable
over the acknowledged prior art in view of Okado and Mihara is reversed.
b) The rejection of claims 13-19 and 21-23 under the judicially created doctrine of
obviousness type double patenting as being unpatentable over claims 1-12 of U.S. Patent
5,303,110 to Kumagai in view of Okado and Mihara is reversed.
REVERSED
STANLEY M. URYNOWICZ, JR. )
Administrative Patent Judge )
)
) BOARD OF PATENT
) APPEALS AND
KENNETH W. HAIRSTON ) INTERFERENCES
Administrative Patent Judge )
)
)
)
RICHARD TORCZON )
Administrative Patent Judge )
Appeal No. 95-0648
Application 08/001,199
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