Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2002-02-07
2004-05-11
Coles, Edward (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C356S430000, C356S431000, C356S237100, C356S237200
Reexamination Certificate
active
06734997
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a method for detecting defects on a transparent film in a scanner, and more specifically to a method that lengthens or shortens the exposure time to detect defects on a transparent film in a scanner.
2. Description of the Prior Art
As computer technology develops, peripheral devices also change with each passing day. The scanner is an excellent example of this. Scanners are used to scan a transparent film so as to obtain corresponding digital image signals. In general, the film is easily contaminated by dust and hair, or easily scratched. As a result, defects will be formed on the film and damage the scanned image. Therefore, high quality scanners always have the function of repairing the defects.
Please refer to FIG.
1
.
FIG. 1
is a functional block diagram of a prior art scanner
10
. The scanner
10
is used to scan a transparent film
14
. The scanner
10
comprises a white light source
12
a
, an infrared light source
12
b
, and a light sensor
16
. The white light source
12
a
is used to generate white light, and the infrared light source
12
b
is used to generate infrared light. The white light is composed of red light, green light and bluelight. The light sensor
16
comprises a plurality of red light charge-coupled devices
16
a
arranged in order, a plurality of green light charge-coupled devices
16
b
arranged in order, and a plurality of blue light charge-coupled devices
16
c
arranged in order. The charge-coupled devices
16
a
,
16
b
and
16
c
each generate a corresponding electric charge when the white light passes through the transparent film
14
. In addition, the light sensor
16
further comprises a plurality of infrared charge-coupled devices
16
d
arranged in order for generating a corresponding electric charge in the charge-coupled devices
16
d
when the infrared light passes through the transparent film
14
. A computer system
18
electrically connects with the light sensor
16
for processing the output of the light sensor
16
.
Please refer to FIG.
2
.
FIG. 2
is a flow chart showing how the prior art scanner
10
detects defects on the transparent film
14
. The procedures of the prior art method for detecting defects on the transparent film
14
are: Step
22
:Switch on the white light source
12
a
and scanning the transparent film
14
so as to obtain white light image signals;Step
24
:Switch on the infrared light source
12
b
and scan the transparent film
14
so as to obtain infrared image signals;Step
26
:Find out the defect positions according to the white light image signals and the infrared image signals; andStep
28
:Use the computer system
18
to repair the defect positions.
In step
22
and step
24
, the white light source
12
a
and infrared light source
12
b
generate white light and infrared light respectively, so as to scan the transparent film
14
. After that, the white light image signals and infrared image signals will be obtained. The infrared light can pass through transparent film
14
, but not transparent film
14
with the defects of dirt and scratches. The response speed of the infrared charge-coupled device
16
d
to the infrared light is the fastest compared with the response speed of the red light charge-coupled device
16
a
to the red light, green light charge-coupled device
16
b
to the green light, and the blue light charge-coupled device
16
c
to the blue light. That means the plurality of infrared light charge-coupled devices
16
d
arranged in order will quickly reach a saturation level after receiving the infrared light. Therefore, after step
24
is finished, the digital image signals, which are generated by the unsaturated infrared charge-coupled device
16
d
, represent the image signals generated by the defects of the dirt or the scratches. Therefore, the computer system
18
is able to detect the defect positions of the dirt or the scratches according to the output of the infrared charge-coupled device
16
d
. The computer system
18
then uses a software operation to repair and process the corresponding defect positions of the scanned image signals, so as to obtain image signals without defects of dirt or scratches and achieve the purpose of removing the dirt or scratches from the image.
However, to scan transparent film
14
, the prior art scanner
10
needs to have the infrared light source
12
b
and the plurality of infrared charge-coupled devices
16
d
installed when it scans the transparent film
14
. This will complicate the mechanical design of the scanner and make fabrication more difficult, increasing the cost.
SUMMARY OF INVENTION
It is therefore a primary objective of the claimed invention to provide a method for detecting defects on a transparent film in a scanner, to overcome the shortcomings of the prior art.
The claimed invention, briefly summarized, discloses a method for detecting defects on a transparent film in a scanner. The scanner has a light source for the transparent film. The method includes using the light source to expose the transparent film for a first predetermined time to generate a first image, using the light source to expose the transparent film for a second predetermined time to generate a second image, and comparing differences between the first image and the second image according to a time ratio of the first predetermined time and the second predetermined time so as to detect the defects on the transparent film.
It is an advantage that the method of the claimed invention does not need to install the infrared light source and infrared charge-coupled device. This not only reduces the cost of the electric system, but also simplifies the mechanical design of the scanner.
These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
REFERENCES:
patent: 3958078 (1976-05-01), Fowler et al.
patent: 5642198 (1997-06-01), Long
patent: 6055400 (2000-04-01), Emukai et al.
patent: 6222624 (2001-04-01), Yonezawa
Avision Inc.
Coles Edward
Hsu Winston
Safaipour Houshang
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