Ex parte Andrews

Board of Patent Appeals and Interferences

Jul 30, 2001

08734319 (B.P.A.I. Jul. 30, 2001)

1
The opinion in support of the decision being entered today was not written for publication
and is not binding precedent of the Board.
Paper No. 12
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte JOHN R. ANDREWS
_____________
Appeal No. 1999-1931
Application No. 08/734,319
______________
ON BRIEF
_______________
Before KRASS, GROSS, and BLANKENSHIP, Administrative Patent Judges.
KRASS, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal from the final rejection of claims 1-8, all of the pending
claims.
The invention is directed to improved exposure profiles for laser sources having
finite response times. More particularly, in electrophotographic marking machines,
problems caused by edge misplacements caused by delays in a laser diode’s turn-on and
turn-off times are solved by determining whether a pixel being imaged forms a leading or a
Appeal No. 1999-1931
Application No. 08/734,319
2
trailing edge of a solid section of an image area. If the pixel forms an edge, the laser
diode’s exposure of that edge is advanced or delayed such that the pixel is properly
located. The amount of advancement or delay depends upon the exposure versus
time/distance characteristics of the imaging station.
Representative independent claim 8 is reproduced as follows:
8. A method of illuminating a photoreceptor comprised of the steps of:
generating a sequence of timing signal;
producing a sequence of image data bits that represent a composite
image comprised of standard image areas and image edges;
sensing the image data bits that represent image edges; and
producing laser light in according with the sequence of image data
bits, wherein the laser light is produced in synchronization with the timing
signals when an image data bit represents a standard image area, and
wherein the laser light is produced earlier when an image data bit represents
an image edge.
The examiner relies on the following references:
Monma et al. (Monma) 4,928,277 May 22, 1990
Hirota 5,357,353 Oct., 18, 1994
Nye et al. (Nye) 5,570,173 Oct. 29, 1996
(filed Oct. 31, 1994)
Kovacs et al. (Kovacs) 5,646,968 Jul. 08, 1997
(filed Nov. 17, 1995)
Claims 1-8 stand rejected under 35 U.S.C. § 103. As evidence of obviousness, the
examiner offers Monma, Hirota and Nye with regard to claims 1-4 and 6-8, adding Kovacs
with regard to claim 5.
Appeal No. 1999-1931
Application No. 08/734,319
3
Reference is made to the brief and answer for the respective positions of appellant
and the examiner.
OPINION
At the outset, we note that, in accordance with appellant’s grouping at page 3 of the
brief, all claims will stand or fall together.
It is the examiner’s position that Monma discloses the claimed subject matter but for
1. an edge sensor operatively connected to the electronic subsystem for sensing image
edges and 2. a developing station, a transfer station and a fuser for transferring the image
to a recording medium. The examiner employs Hirota for the teaching of an image forming
apparatus having an edge detector for detecting an image edge in the main scanning
direction for the purpose of smoothing or emphasizing the edge. Nye is employed for its
disclosure of a color printer having a charging unit, a development station, a liquefaction
stage and a transfixing station.
The examiner concludes that since all of these references are in the same field of
endeavor, it would have been obvious to implement an edge detector as taught by
Hirota, and the various processing stations as taught by Nye, in the image recording
apparatus of Monma for the purpose of improving image reproduction.
Appellant offers no argument as to the application of Nye for its disclosure of the
various processing stations in an electrophotographic printing machine and we take
Appeal No. 1999-1931
Application No. 08/734,319
4
appellant’s silence as an acknowledgment of the existence of these processing stations in
such systems.
The issue, then, is the application of Monma, together with Hirota, in rejecting the
instant claims.
The instant claims all require, in one form or another, that the drive signals produced
by the laser driver are “produced earlier than said active edges when an image data bit
represents an image edge” while the drive signals are produced synchronously with the
active edges when an image data bit represents a standard image area. Thus, a laser is
turned ON earlier when a solid image is produced so as to more accurately locate the
edge placement.
In contrast, Monma is concerned with compensating for “laser droop” wherein the
amount of light emitted from a laser diode immediately after the laser diode is energized
“becomes a few % greater than a desired target amount of light” [column 2, lines 7-8].
Monma does have many of the same elements as set forth in the instant claims, and
does recite [column 2, lines 54-64] an object of the invention is
to provide...for driving a laser beam source to energize/de-energize laser
oscillation for exposing a subject or original while supplying a bias
current of a level lower than a threshold level of the laser beam source
to a laser diode, by starting to supply the bias current to the laser diode
at a position in front of a leading edge of the subject and behind a trailing
edge of a preceding subject for thereby preventing a reproduced image
Appeal No. 1999-1931
Application No. 08/734,319
5
of the subject from being fogged in its entirety or losing image edge
sharpness.
Appellant argues that Monma addresses a completely different problem than that of
the subject invention and that the methods of addressing these different problems are,
themselves, completely different [brief-page 4]. In particular, appellant argues that
whereas Monma uses a switched bias scheme for laser diodes that corrects for laser
droop while avoiding problems that result from using a constant bias level, the instant
invention teaches a system in which a laser is turned ON and OFF slightly earlier when a
“solid” image is produced so as to more accurately locate the edge placement. Appellant
argues that “Monma...do not teach early turn on or early turn off, while the subject invention
does not teach a bias level droop improvement. Therefore, adding the edge detector of
Hirota to Monma...still does not render the subject invention obvious” [brief-bottom of page
4].
While we do not find appellant’s arguments to be a beacon of clarity with regard to
particularly pointing out the differences between the instant claimed invention and that
disclosed by Monma, we will, nevertheless, reverse the examiner’s rejections since, in our
view, the examiner has not established a prima facie case of obviousness.
While Monma does teach, with regard to a laser diode, an operation earlier than, or
in front of, a leading edge of a subject, it is clear, from column 2 of Monma, that
Appeal No. 1999-1931
Application No. 08/734,319
6
Monma is not turning a laser diode ON and OFF, i.e., providing drive signals from image
data bits, as claimed, wherein drive signals are provided earlier than an active edge when
an image data bit represents an image edge. Rather, it appears from our review of
Monma that the laser diode is already ON but that a bias current is provided to the laser
beam source, wherein the bias current is lower than a threshold current. It is this bias
current that is supplied to the laser diode at a position in front of a leading edge of the
subject and behind a trailing edge of a preceding subject for preventing irregularities in an
image. Thus, Monma appears to affect, or limit, the intensity of a laser diode, starting the
bias current at a position in front of a leading edge of the subject because, left
uncompensated, the amount of light emitted from the laser diode immediately after the
laser diode is energized would be a little greater than a desired target amount of light.
Thus, the bias current is started to be supplied to the laser
diode at a position in front of the leading edge of the subject for compensation purposes,
preventing an irregular image. The laser driver does not appear to be producing drive
signals (which turn the laser diode ON) earlier than the active edges when an image data
bit represents an image edge, as claimed.
Moreover, even the examiner admits that Monma does not disclose an edge
sensor, as claimed. It is unclear to us why the artisan would look to Hirota for an edge
Appeal No. 1999-1931
Application No. 08/734,319
7
sensor to be employed in Monma nor is it clear to us how, exactly, the artisan would apply
such an edge sensor in Monma to give Monma’s system anything it does not already have.
We note the addition of the Kovacs reference with regard to dependent claim 5 but
Kovacs was applied for the teaching of a look-up table connected to a clock and we find
nothing in Kovacs that would have provided for the deficiencies noted supra with regard to
the primary references.
The examiner’s decision rejecting claims 1-8 under 35 U.S.C. § 103 is reversed.
REVERSED
ERROL A. KRASS )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
ANITA PELLMAN GROSS ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
HOWARD B. BLANKENSHIP )
Administrative Patent Judge )
eak/vsh
Appeal No. 1999-1931
Application No. 08/734,319
8
RONALD ZIBELLI
XEROX CORP
XEROX SQUARE 20A
ROCHESTER NY 14644