Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1996-11-12
2001-11-20
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S474000
Reexamination Certificate
active
06320679
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image scanner and more particularly to an image scanner using a line sensor as a light-receiving means.
BACKGROUND OF THE INVENTION
As an example of the conventional image scanner, a handy scanner
1
employing a condenser system is shown in FIG.
3
. This scanner includes a lower casing
2
containing, in the order from right to left in the view, an LED
3
as light-emitting means, a condenser system
4
and a line sensor (PD)
5
as light-receiving means. Disposed close to one end of the lower casing
2
is a roller
7
as a sensor means for detecting the relative amount of movement between the reading position of the PD
5
and the image on a document
6
.
The LED
3
is attached to the lower casing
2
with a holder
8
and the light emitted from the LED
3
passes through an aperture
9
formed in the lower casing
2
and is incident on the upper surface of the document
6
. The reflected light from the document
6
is reflected by a mirror
10
secured to said holder
8
and guided to the condenser system
4
through a light path
11
. The condenser system
4
is composed of a plurality of lenses
13
supported by a holder
12
which is rigidly secured to a first base plate
14
disposed in parallel with the lower casing
2
.
The lower casing
2
is provided with a holder plate
15
making an angle of 90° therewith and a second base plate
17
and the PD
5
are fixedly secured to the holder plate
15
by means of a screw
16
. The light guided through the light path
11
is focused on the PD
5
, where it is converted to an electric signal by the photoelectric transducer, and the resulting signal is fed to a reader device not shown through a cable
18
. Rotatably mounted on the underside of the lower casing
2
in the vicinity of PD
5
through a shaft
19
is an auxiliary roller
20
.
On the other hand, a supporting shaft
21
for a sensor roller
7
is rotatably supported by a bearing
22
disposed on the lower casing
2
and a drive gear
23
is rigidly mounted in concentric relation with the roller
7
. The lower casing
2
is further provided with an encoder
25
through a supporting member
24
and a driven gear
27
is concentrically mounted on a shaft
26
of the encoder
25
. The driven gear
27
is driven by the drive gear
23
via the train of gears
28
,
29
and
30
and as the scanner
1
is driven in pressure contact with the document
6
, the encoder
25
detects the reading position.
Dismountably attached to the lower casing
2
by a screw
31
is an upper casing
32
which covers the various component parts mentioned above. Furthermore, the upper casing
32
is provided with a window
33
, which can be freely opened and closed, at one end close to the LED
3
. This window
33
is made of a light-transparent material so that the reading position can be ascertained from above.
In the scanner
1
having the above construction, entry of dust or other foreign matter may adversely affect its electrical system to cause a trouble or failure. Moreover, deposition of dust on the mirror
10
, condenser system
4
or PD
5
would cause local darkening to interfere with proper image reading. Therefore, the lower casing
2
and the upper casing
32
are hermetically sealed together and a transparent member
34
is tightly fitted across an aperture
9
through which the reading light from the LED
3
is projected on the document
6
.
However, the conventional image scanner described above has the following disadvantages. Thus, since the transparent member
34
is located close to the document
6
, the entry of dust in the scanner
1
may result in deposition of the dust on the inner surface of the transparent member
34
. If the deposit of dust occurs within the depth of field of the lens
13
, the resulting shadow of the dust interferes with correct image reading. Moreover, since this deposit of dust occurs in a position closer to the document as compared with the deposit of dust on the other members disposed in the light path, such as the mirror
10
, condenser system
4
and PD
5
, it exerts a well-magnified influence.
The image scanner of the present invention has been developed to overcome the above disadvantages.
It is an object of the invention to provide an image scanner which insures accurate reading of an image without interferences of dust that may deposit on the transparent member.
Other objects and advantages of the invention will become apparent from the following description and accompanying drawings.
SUMMARY OF THE INVENTION
The present invention is, therefore, directed to an image scanner comprising a light-emitting means for projecting light on a document, a light-receiving means for receiving reflected light from said document to read an image thereon, an optical system for focusing said reflected light on said light-receiving means, a sensor means for detecting a relative amount of movement between the reading position of said light receiving means and the position of the image on said document and a housing accommodating said respective means, wherein said housing is provided with a transparent member for guiding said reflected light to said light-receiving means, said transparent member being disposed sufficiently apart from the surface of said document in such a manner that at least its area transmitting the reflected light is located outside of the depth of field.
In accordance with the invention, wherein the transparent member is located away from the depth of field, dust which may deposit on the transparent member will not cast a large shadow on the image-receiving means so that the dimming of the projected image on the light-receiving means is precluded, thus insuring correct image reading.
REFERENCES:
patent: 4422100 (1983-12-01), Duvall et al.
patent: 4893189 (1990-01-01), Kabota et al.
patent: 5023922 (1991-06-01), Abramovitz et al.
patent: 5175422 (1992-12-01), Koizumi et al.
Koizumi Haruyuki
Nishijima Atsuo
Noda Atsushi
Ohtsuka Yuji
Dickstein , Shapiro, Morin & Oshinsky, LLP
Lee Cheukfan
Omron Corporation
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