Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2000-02-11
2004-06-08
Williams, Kimberly (Department: 2626)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S498000, C358S496000, C399S367000
Reexamination Certificate
active
06747763
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention is related to image reader, in particular to the paper feeder of the image reader.
(2) Description of the Related Art
An image reader is usually used in a scanner, a copier, a facsimile machine, etc. All these equipment contain an image reader. To increase the throughput, automatic document feeders (ADF) are customarily used.
FIG. 1
shows such an ADF, including a feeding roller
162
for picking up a sheet of paper
10
to be scanned, a taking up roller
164
to take up the paper
10
after scanning, an upper guide plate
12
; a left lower guide plate
142
; a central lower guide plate
144
; a right lower guide plate
146
. The three lower guide plates and the upper guide plate
12
form a curved conduit for the paper to move and to read the image. The bottom of the central guide plate
133
is transparent and is used to read the image at the bottom of the paper
10
.
An light ray
152
is incident on the bottom side of the paper and is reflected as a ray
154
to an image sensor
18
for image processing.
FIG. 2
shows another common practice. The paper feeding roller
162
, the take-up roller
164
and the upper paper guide
12
function in a similar way as in
FIG. 1
for feeding the paper
10
. However the lower paper guides
242
,
244
and
246
form a unitary transparent arc.
Both the paper guides shown in FIG.
1
and
FIG. 2
have a common drawback as shown in FIG.
3
. Due to the finite distance between the upper paper guide
12
and the lower paper guide
144
, the paper fed between these guides may wrap in the lateral direction orthogonal the direction of the paper feed. The warping may be due to warping of the paper, paper rubbing, air disturbance in the paper passage, or jittering of the rollers
162
,
164
when the rollers are turn on and off.
FIG. 4
shows another cause of paper distortion when the paper
10
wrinkles along lines perpendicular to the direction of the paper movement between the upper guide plate
12
and the lower guide plate
144
.
In FIG.
3
and
FIG. 4
, the image on the paper is read by means of the reflected light rays
1641
,
1642
and
1643
incident on the image sensor
18
, from which the image is processed. Due to paper, an original straight line on the image becomes crooked or distorted. Such a distorted reproduction is not satisfactory to high quality image reproduction.
High quality reproduction especially important for digital processing, such as pattern recognition, digital camera and digital drawings.
SUMMARY OF THE INVENTION
An object of this invention is to improve a paper feeder structure for high quality reproduction of a scanned paper. Another object of this invention is to avoid paper warping in a paper feeder.
These objects are achieved in this invention by putting pressure at the line where the incident light ray is reflected. By exerting pressure, the paper is flattened at the points of light incidence. The pressure may be exerted by a spring, a weight or a roller.
REFERENCES:
patent: 4335954 (1982-06-01), Phelps
patent: 4593323 (1986-06-01), Kanda et al.
patent: 4764807 (1988-08-01), Kimura et al.
patent: 4774591 (1988-09-01), Matsunawa et al.
patent: 4843431 (1989-06-01), Horiguchi et al.
patent: 5157521 (1992-10-01), Chung
patent: 5734483 (1998-03-01), Itoh
patent: 5915691 (1999-06-01), Deguchi et al.
patent: 6069715 (2000-05-01), Wang
Taiwan Patent 358619.
Taiwan Patent 322828.
U.S. Patent No. 5,157,521.
Avision Inc.
Hsu Winston
Williams Kimberly
Worku Negussie
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