Image scanner having driving mechanism to synchronize...

Details Image scanner having driving mechanism to synchronize... Image scanner having driving mechanism to synchronize...

2000-10-26

2002-12-03

Pyo, Kevin (Department: 2878)

Radiant energy

Photocells; circuits and apparatus

Photocell controlled circuit

C250S234000, C358S474000

Reexamination Certificate

active

06489602

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an image scanner, and more particularly to an image scanner which includes a single driving device to synchronously move a transmission-mode light source and an image pickup device located on opposite sides of a scanning platform.
BACKGROUND OF THE INVENTION
For an image scanner for scanning a reflective document such as a photo or a paper document, the light source
14
is generally enclosed in a carriage
15
together with an image pickup device including a mirror set
16
, a lens device
17
and a charge-coupled device (CCD)
18
, as shown in FIG.
1
A. The light from the light source
14
is reflected off of the document
10
and received by the image pickup device
16
,
17
,
18
to realize the image data of the document. By moving the carriage
15
across the document
10
placed on a scanning platform
20
to be scanned, a scanning operation, so called as a reflection-mode scanning, is performed. The light source
14
is referred as a reflection-mode light source herein. Owing to the integration of the light source
14
, mirror set
16
, lens device
17
and CCD
18
in the carriage
15
, only one driving device
12
is required to move the light source and the image pickup device across the document. The driving device
12
generally includes a motor
191
and plural gears
192
.
On the other hand, for an image scanner for scanning a penetrative document such as a negative film, a projecting film or a slide, the image pickup device including the mirror set
16
, lens device
17
, and CCD
18
is enclosed in the carriage
15
, and the light source
13
is disposed opposite to the carriage
15
relative to the scanning platform
20
, as shown in FIG.
1
B. The light from the light source
13
penetrates through the document
10
and received by the image pickup device
16
,
17
,
18
to realize the image data of the document. By moving the carriage
15
across the document
10
placed on the scanning platform
20
to be scanned, a scanning operation, so called as a transmission-mode scanning, is performed. The light source
13
is referred as a transmission-mode light source herein. Owing to the separation of the light source and the image pickup device, one driving device
11
is required to move the transmission-mode light source
13
, and another driving device
12
is required to move the carriage
15
.
For a dual-mode image scanner, a transmission-mode scanning or a reflection-mode scanning is performed optionally. For sharing a single image pickup device which is relatively expensive, both of the transmission-mode and the reflection-mode light sources are required, as shown in FIG.
1
C. In the conventional dual-mode image scanner, the two driving devices
11
and
12
are used to move the transmission-mode light source
13
and the reflection-mode light source
14
which is mounted in the carriage
15
together with the mirror set
16
, the lens device
17
and the CCD
18
, respectively. According to the type of the document
10
to be scanned, either one of the transmission-mode light source
13
and the reflection-mode light source
14
is energized. When a transmission-mode scanning is performed, it is necessary for the transmission-mode light source
13
to be synchronously moved with the carriage
15
in order to allow the light emitted therefrom and penetrating through the document
10
to precisely reach the mirror set
16
and further the lens device
17
and the CCD
18
. In other words, it is important to perfectly synchronize the movement of the light source
13
with that of the carriage
15
. However, such a synchronizing operation is not easy to achieve. Further, owing to the presence of two driving devices including motors
191
and gears
192
, the image scanner may be undesirably bulky.
For reducing to a single driving device, a driving mechanism as shown in
FIG. 2
is suggested to simultaneously move the transmission-mode light source and the carriage. Similar to the image scanner of
FIG. 1
, the reflection-mode light source (not shown) is mounted in a carriage
25
which is moved by a driving device. In this image scanner, two guiding slots
211
beside the scanning window
29
are created, and two connecting rods
212
are provided. The two opposite connecting rods
212
penetrate the slots
211
and connect the transmission-mode light source
23
to the carriage
25
. With the driving of a motor and gears (not shown, with reference to FIG.
1
), the carriage
25
transmits the light source
23
connected therewith through the connecting rods to move synchronously. Therefore, only one set of driving motor and gears is required, and no misalignment problem will occur. U.S. Pat. No. 5,251,072, which is incorporated herein for reference, also describes a similar driving mechanism to synchronize the movement of the transmission-mode and the reflection-mode light sources.
The image scanner of
FIG. 2
, though omitting one set of motor and gears to possibly reduce the thickness of the scanner housing, requires additional width to create the two guiding slots. Furthermore, the presence of the guiding slots renders contaminants such as dusts to have a chance to enter the lower housing where the important optical devices are accommodated.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a dual-mode image scanner, in which a single driving device is used to synchronize the movement of a transmission-mode and a reflection-mode light sources without creating any long slots beside a scanning window.
Another object of the present invention is to provide a transmission-mode image scanner, in which a single driving device is used to synchronize the movement of a light source and an image pickup device enclosed in a carriage precisely and conveniently.
According to the present invention, an image scanner includes a scanning platform for placing thereon a document to be scanned, a housing including a lower housing, and an upper cover pivotally connected to the lower housing at an upper end of the scanning platform, a transmission-mode light provider accommodated in the housing for providing a light signal for the document to be scanned, an image pickup device accommodated in said housing at a side of the scanning platform opposite to the transmission-mode light provider for receiving an image signal from the document in response to the light signal, and converting the image signal into an electronic signal, and a driving device connected between the transmission-mode light provider and the image pickup device for synchronously moving the transmission-mode and the image pickup device.
According to the present invention, the driving device includes a driving element for simultaneously providing a driving force for the transmission-mode light provider and the image pickup device, a first transmission device connected between the driving element and the image pickup device for moving the reflection-mode light provider in response to the driving force, and a second transmission device connected between the driving element and the transmission-mode light provider for moving the transmission-mode light provider in response to the driving force.
According to the present invention, the first or the second transmission devices penetrates through the scanning platform at the upper end, depending on the positions of the transmission-mode light provider, the image pickup device, and the driving element.
For example, if the transmission-mode light provider is located in the upper cover, and the driving element and the image pickup device are located in the lower housing, then the first transmission device are located in the lower housing, and the second transmission device penetrates through the scanning platform at the upper end.
Preferably, the driving element is a motor.
Preferably, the second transmission device includes a roller mounted in the lower housing beneath the upper end of the scanning platform, and driven to rotate by the motor, a first pulley mounted in the upper

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