Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2002-07-19
2003-08-12
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06604801
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for adjusting a head gap between printing paper and a nozzle of a printing head in an inkjet printer, and more particularly, to an apparatus for automatically adjusting a head gap according to a change in thickness of printing paper in an inkjet printer.
2. Description of the Related Art
Generally, an inkjet printer, as shown in
FIG. 1
, includes a printing head
30
having a nozzle
31
at a lower part thereof to eject ink through the nozzle
31
, a carrier
20
mounted with the printing head
30
therein, and a chassis
10
having a guide rail
11
and a carrier shaft
50
both guiding a movement of the carrier
20
. At a rear part of the carrier
20
, a supporting bracket
51
and a guide slider
22
are formed to allow the carrier
20
to be movable right and left along the carrier shaft
50
and the guide rail
11
, respectively.
Thus, when printing paper
40
passes below a lower part of the printing head
30
through a paper-transporting roller
60
after being picked up from a paper-storing tray or a cassette by a pick-up roller (not shown), the printing head
30
mounted in the carrier
20
is moved right and left along the carrier shaft
50
and the guide rail
11
to perform a printing operation of ejecting the ink onto the printing paper
40
through the nozzle
31
. Discharging rollers
70
,
80
are disposed at a paper discharging portion of the inkjet printer.
However, in the inkjet printer, a distance or a head gap between the printing paper
40
and the nozzle
31
of the printing head
30
is generally fixed. Accordingly, when the inkjet printer prints an envelope or a postcard having a thickness of two or three times greater than that of general paper, the head gap is considerably reduced compared with that of when the general paper is printed, and the printing head
30
may be tilted with respect to the envelope or the post card. In this case, a spread or smear of the ink resulting in a problem of deterioration of a printing quality may be generated.
To solve the above problem, in the conventional inkjet printer, an apparatus
90
which can manually adjust the head gap between the printing paper
40
and the printing head
30
according to the thickness of the printing paper
40
is installed as shown in
FIGS. 1 and 2
. The apparatus
90
includes a carrier guide
21
formed in the guide slider
22
at an upper part of the carrier
20
, a cam
23
having a cam surface mounted on the carrier to move the carrier
20
with respect to the chassis
10
, a compression spring
24
biasing the carrier guide
21
to come in contact with the cam
23
, and a spring guide
25
receiving and supporting the compression spring
24
.
In operation, when the envelope, the postcard and the like are printed, the head gap is to be increased, and the cam
23
is rotated in a direction B by a user to push the carrier guide
21
.
At this time, since the spring guide
25
is fixed to the carrier
20
, the carrier guide
21
is biased in a direction D by a repulsive power of the compression spring
24
. However, since the guide slider
22
elastically coupled to the carrier guide
21
is disposed not to be movable back and forth but to be slidable right and left along the guide rail
11
, the guide slider
22
is not moved, but the spring guide
25
is backward pushed as much as the eccentricity of the cam surface of the cam
23
.
As the spring guide
25
fixed to the carrier
20
is backward pushed, the carrier
20
mounted with the printing head
30
is rotated in a direction C about the carrier shaft
50
. As a result, front parts of the carrier
20
and the nozzle
31
of the printing head
30
are rotated about the carrier shaft
50
.
On the contrary, when the general paper is printed, the head gap is to be decreased, and the cam
23
is rotated in a reverse direction. As a result, the carrier
20
is rotated about the carrier shaft
50
and descended into the former position.
However, since in the conventional inkjet printer, the front part of the carrier
20
is ascended or descended to increase or decrease the head gap, there was a problem that the nozzle
31
of the printing head
30
is arranged to be tilted with respect to the printing paper
40
. In this case, since there exists a difference in height between front and rear ends of the nozzle
31
a deflection or variation in the printing quality can occur at beginning and ending portions of the printing paper
40
which is printed by the nozzle
31
.
Although the conventional inkjet printer may adjust the head gap with the above explained structure, to adjust t,he head gap, the user has to move the cam
23
whenever the kind of the printing paper
40
is changed, and consequently an operation error as well as inconvenience and troublesomeness may occur.
To improve these problems, as shown in
FIG. 3
, there has been proposed a method of ascending and descending a carrier
20
′ by forming both ends
50
″,
50
′″ of a carrier shaft
50
′ in the form of an eccentric cam having a given eccentricity &dgr; and then connecting the carrier shaft
50
′ with a transmission (not shown) which is driven by a separate driving motor. However, since the method uses an additional driving motor and a transmission unit, a manufacturing cost increases, and an additional space for the driving motor and transmission is required, thereby resulting in an increase in size of the inkjet printer.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an improved apparatus in an inkjet printer for adjusting a head gap between printing paper and a printing head according to a change in thickness of the printing paper.
It is another object to provide an improved apparatus in an inkjet printer for automatically adjusting a head gap between printing paper and a printing head by using only a driving force of a carrier driving motor and a paper-transporting roller driving motor without using a separate additional driving motor.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
These and other objects may be achieved, according to an embodiment of the present invention, by providing an apparatus for adjusting a gap between printing paper and a nozzle of a printing head ejecting ink on the printing paper in an inkjet printer. The apparatus includes a carrier mounted with the printing head, a chassis having a carrier shaft guiding a movement of the carrier, a carrier driving part moving the carrier right and left along the carrier shaft, a paper-transporting roller driving part driving a paper-transporting roller to transport the printing paper to be printed, a carrier ascent/descent part ascending and descending the carrier by rotating the carrier shaft with respect to the carrier and a clutch unit transmitting a driving force of the paper-transporting roller driving part to the carrier shaft and disposed to be actuated by the carrier which is moved by the carrier driving part when the gap should be adjusted.
The clutch unit includes a clutch part selectively transmitting the driving force of the paper-transporting roller driving part to the carrier shaft, and an actuator actuating the clutch part to transmit the driving force of the paper-transporting roller driving part to the carrier shaft.
The clutch part includes an eccentric rotation gear formed at one end of the carrier shaft and a clutch disposed at the chassis to connect or disconnect the paper-transporting roller driving part to or from the eccentric rotation gear. In this case, it is possible that the carrier ascent/descent part has both ends of the carrier shaft formed of in the form of an eccentric cam which a center axis thereof is eccentrically positioned as much as a given amount with respect to a center axis of the carrier shaft, supporting bushings formed at t
Gordon Raquel Yvette
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
Stewart Jr. Charles W.
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