Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-08-05
2004-11-16
Williams, Kimberly (Department: 2626)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S475000, C358S509000, C358S496000, C358S497000
Reexamination Certificate
active
06819456
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an image scanner of low manufacturing cost and high scanning quality.
2. Description of the Related Art
Generally speaking, flat bed type image scanners are classified into two different kinds in accordance with their different operation ways: reflection-type scanners and transmission-type scanners. The reflection-type scanners are used for scanning non-transparent media such as paper, objects and books. On the other hand, the transmission-type scanners are used for scanning transparent media such as films and slides.
The present invention is related to the transmission-type scanners. Conventional transmission-type scanners include two kinds of light sources: movable and fixed.
FIG. 1
is a schematic diagram of a conventional transmission-type scanner provided with a movable light source, wherein a tubular lamp
11
and an optical module
14
are simultaneously moved to scan a transparent object
12
disposed on a piece of glass
13
. The image of the transparent object
12
is focused on a charge-coupled device (CCD)
15
contained in the optical module
14
. Such a scanner can be put into practice in various ways. For example, what is disclosed in Taiwanese Patent No. 311791.
In the above example, the distribution of intensity of illumination of the tubular lamp
11
is very concentrated, as shown in FIG.
2
. If at any moment the movement of the optical module
14
and that of the tubular lamp
11
are not simultaneous, then the light received by the charge-coupled device
15
will be greatly reduced. Thus, the resultant image signal obtained from the charge-coupled device
15
is poor. Therefore, the movement of the optical module
14
and that of the tubular lamp
11
should be always kept simultaneous during the scanning process. However, the tubular lamp
11
and the optical module
14
generally are driven by different mechanisms so that keeping the tubular lamp
11
and the optical module
14
simultaneous is pretty complicated and difficult.
FIG. 3
depicts a conventional scanner provided with a fixed light source, where the light source is a planar light source
31
disclosed in, for example, Taiwanese Patent No. 292032. The planar light source
31
includes two tubular lamps
311
, a reflection sheet
315
, a lighting guide
317
and a diffuser
316
. The reflection sheet
315
is provided on the top of the planar light source
31
to reflect the light of the tubular lamps
311
. The lighting guide
317
is used to uniformly distribute the light reflected by the reflection sheet
315
via a plurality of light-guiding dots
318
provided thereon. The diffuser
316
is also utilized to uniformly distribute the light reflected by the reflection sheet
315
. Both the lighting guide
317
and the diffuser
316
are of great size. In operations, the planar light source
31
is stationary while an optical module
34
is moved to scan a transparent object
32
disposed on a piece of glass
33
. The image of the object
32
is focused on a charge-coupled device (CCD)
35
contained in the optical module
34
.
Due to the use of the reflection sheet
315
, diffuser
316
and lighting guide
317
, the distribution of intensity in this example is much more uniform than that of the previous example. Nevertheless, the intensity difference between the middle and sides of the planar light source is 5%-10% that does not satisfy the requirement for a scanner of high revolution. In addition, forming light-guiding dots
318
on the lighting guide
317
is labor consuming. The greater size of the lighting guide
317
is, the more light-guiding dots
318
are required; thus, the manufacture of lighting guides is difficult and expensive.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a scanner that solves the above-mentioned problems.
In accordance with the object of the present invention, an image scanner comprising an image pick-up device and a planar light source is provided. Backlight is generated by the planar light source to transmit through a transparent object. The image pick-up device is used to retrieve the image of the transparent object, i.e., the image of the transparent object is focused on the image pick-up device. In scanning operations, the planar light source and the image pick-up device are simultaneously moved to scan the transparent object.
As described above, the planar light source of the present invention is moved to project backlight onto the simultaneously moving image pick-up device. Accordingly, the size of the planar light source can be small. A lighting guide in the planar light source is also of small size and has fewer light-guiding dots provided thereon; thus, manufacture of the lighting guide of the present invention is easier than that of the prior art. In addition, the distribution of light intensity in the present invention employing the small lighting guide is more uniform than that in the prior art employing the large lighting guide. The difference between the illumination on the middle of the transparent object and the illumination on the sides of the transparent object is less than 1% in the present invention, that is superior to 5%-10% in the prior art. Therefore, the scanning quality of the present invention is superior to that of the prior art.
REFERENCES:
patent: 4750003 (1988-06-01), Terashima et al.
patent: 4982235 (1991-01-01), Fujino
patent: 4989099 (1991-01-01), Koshiyouji et al.
patent: 5038227 (1991-08-01), Koshiyouji
patent: 5126839 (1992-06-01), Sugiura
patent: 5367382 (1994-11-01), Bhatt et al.
patent: 5781311 (1998-07-01), Inoue
patent: 6081630 (2000-06-01), Kaneko
patent: 04-261261 (1992-09-01), None
Abstract of JP 04-261261,Patent Abstracts of Japan, (2000).
U.S. patent application Ser. No. 09/427,111, Chen, filed Oct. 1999.
BENQ Corporation
Ladas & Parry LLP
Williams Kimberly
Worku Negussie
LandOfFree
Scanner provided with movable planar light source does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Scanner provided with movable planar light source, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scanner provided with movable planar light source will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3329594