Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2000-10-26
2004-02-03
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S474000, C358S471000
Reexamination Certificate
active
06687027
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an optical chassis for scanner and particularly to a parallel driving mechanism for the optical chassis to move parallelly during scanning operation.
BACKGROUND OF THE INVENTION
Scanner is a widely used computer peripheral device that uses an optical chassis for housing the mirrors, lamp, lens set and CCD to scan a document for capturing and converting document image into digital signals for computer process.
FIG. 1
shows a typical conventional scanner optical apparatus which includes a casing
10
, an optical chassis
20
and a transmission means
301
. The casing
10
is hollow and includes four side walls
12
and a bottom wall
14
. In the casing
10
, there is a guide rail
16
at one side and a guide rod
18
located parallelly at another side for providing linear moving path to the optical chassis
20
.
The optical chassis
20
is mounted with a lamp, several mirrors, a lens set and a charge coupled device (CCD, not shown in the figure) for capturing document image.
The optical chassis
20
further has a roller
22
movable on the guide rail
16
, a guide bore
24
slidably holds the guide rod
18
and a clamp
26
located at one end thereof.
The transmission means
30
includes a motor
32
and a belt
34
engaged with the clamp
26
. When the motor
30
rotates and drives the belt
34
, the optical chassis
20
will be moved reciprocally along the guide rail
16
and guide rod
18
to perform scanning operation.
As the clamp
26
is located at one end of the optical chassis
20
, when the moving belt
34
drags the optical chassis
20
through the clamp
26
to move along the guide rail
16
and guide rod
18
, a torque will incur to optical chassis
20
and result in skew position. The friction between the guide bore
24
and guide rod
18
will increase. The motion might become rough and tremble between the guide bore
24
and guide rod
18
, and between the roller
22
and guide rail
16
. All this may have negative impact on scanning quality.
Since the optical chassis
20
is not a homogenous member, its center gravity is difficult to locate precisely. It is therefore difficult to locate a precise dragging point for the clamp. Furthermore, the guide rail
16
and guide rod
18
have different friction coefficient against the roller
22
and guide bore
24
, the friction unbalance between the two cannot be totally eliminated. Hence the motion of the optical chassis
20
during scanning operation cannot always be as smooth as desired, which unavoidably impacts scanning quality. There is still room for improvement in the driving mechanism for optical chassis in the scanner.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a parallel driving mechanism for scanner that will move the optical chassis horizontally and steadily during scanning operation for obtaining improved scanning quality.
The parallel driving mechanism according to this invention includes a casing, an optical chassis, a linkage member, a screw bar and a driving member.
The casing is hollow and rectangular, and has four side walls and a bottom wall. On one side wall, there is a pair of symmetrical pivotal joints. On the bottom wall, there is a pair of parallel guide rails. The optical chassis has two rollers mounted at two ends for supporting and moving the optical chassis on the guide rails and a pair of symmetrical pivotal joints located on a side wall there of. The linkage member has a pair of upper links pivotally engaged with a pair of lower links at one end thereof. Another ends of the upper and lower links engaged respectively with the pivotal joints at the side wall of the casing and optical chassis. The pivotal engaging joints of the upper and lower links are located respectively on a sleeve which has opposite internal screw threads. The screw bar engaged with the two sleeves and has one end engaged with the driving member. When the driving member rotates the screw bar, the two sleeves will be turned in opposite direction, thus will extend or withdraw the upper and lower links simultaneously. Consequently the optical chassis will be pushed or pulled at the two pivotal joints at the aide wall thereof for moving the optical chassis smoothly and steadily along the guide rails for scanning operation.
REFERENCES:
patent: 4870502 (1989-09-01), Dreinhoff et al.
patent: 5691825 (1997-11-01), Fujiwara
patent: 5734483 (1998-03-01), Itoh
patent: 5781313 (1998-07-01), Nose et al.
patent: 5900951 (1999-05-01), Tsai
patent: 5999277 (1999-12-01), Tsai
patent: 6005685 (1999-12-01), Tsai
patent: 6091517 (2000-07-01), Hayashi
patent: 6108108 (2000-08-01), Peng
patent: 6266164 (2001-07-01), Chiang
patent: 6285441 (2001-09-01), Takahara
patent: 6381041 (2002-04-01), Hayashi et al.
patent: 6535305 (2003-03-01), Chang et al.
Lee Cheukfan
Umax Data Systems
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