Testing nozzles in print heads

Details Testing nozzles in print heads Testing nozzles in print heads

2001-04-30

2004-02-17

Hsieh, Shih-wen (Department: 2861)

Incremental printing of symbolic information

Ink jet

Ejector mechanism

C347S081000

Reexamination Certificate

active

06692099

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to printer devices. More particularly, the invention pertains to a multichannel system and a method for simultaneously detecting malfunctioning nozzles in a plurality of print heads of a large format printer device to thereby reduce the amount of time required to test whether the nozzles are operating properly.
BACKGROUND OF THE INVENTION
It is known to produce copies of files on a print media from a host device, e.g., a computer, a facsimile machine, a photocopier, etc., using a printer device. Among the known methods for printing text and the like onto a print medium, it is known to build an image on the print medium by spraying droplets of ink from nozzles provided on print heads of a printer.
As seen in
FIG. 1
, there is schematically illustrated a part of a known printer device (e.g., a large format printing device) having an array of print heads
100
in a parallel row. More specifically,
FIG. 1
illustrates six print heads
102
-
112
. Each of the print heads
102
-
112
includes a plurality of printer nozzles
202
-
200
n
, arranged in two rows, (see
FIG. 2
) for firing ink onto a print medium
120
. Although
FIG. 1
depicts the printer device as having six print heads
102
-
112
, printer devices have been known to possess any number of print heads, e.g., two, four, or more. Additionally, although
FIG. 2
depicts the print heads
102
-
112
as possessing two rows of nozzles
202
-
202
n
, print heads have been known to possess any number of nozzle rows, e.g., one, two, or more.
Referring back to
FIG. 1
, in a conventional printer device, the print heads
102
-
112
are constrained to move in a direction
170
with respect to the print medium
120
, e.g., a sheet of paper. In addition, the print medium
120
is also constrained to move in a further direction
160
. During a normal print operation, the print heads
102
-
112
are moved into a first position with respect to the print medium
120
and a plurality of ink droplets are fired from the same plurality of printer nozzles contained within each of the print heads
102
-
112
. After completion of a print operation, the print heads
102
-
112
are moved in a direction
170
to a second position and another print operation is performed. In a like manner, the print heads
102
-
112
are repeatedly moved in a direction
170
across the print medium
120
and a print operation is performed after each such movement of the print heads
102
-
112
. When the print heads
102
-
112
reach an edge of the print medium
120
, the print medium is moved a short distance in a direction
160
, parallel to a main length of the print medium
120
, and another print operation is performed. The print heads
1021
112
are then moved in a direction
170
back across the print medium
120
and yet another print operation is performed. In this manner, a complete printed page may be produced.
A more detailed description of the printer device illustrated in
FIG. 1
may be found in commonly assigned application Ser. No. 09/502,667, filed on Feb. 11, 2000, by Xavier Bruch et al., (corresponding to Application No. 20020140760, published on Oct. 3, 2002, now U.S. Pat. No. 6,517,183, issued on Feb. 11, 2003), the disclosure of which is hereby incorporated herein by reference in its entirety.
In order to maintain the quality of the printed output of the printer device, it is important to determine whether each of the nozzles provided on each of the print heads
102
-
112
is functioning properly. In conventional printers, it is known to attempt to detect an ink droplet as it leaves the nozzle between certain print operations. In this respect, a drop detector module
130
is typically used to determine the health (i.e., the proper functioning) of the printer nozzles
200
-
200
n
. As seen in
FIG. 1
, a drop detector module
130
is typically provided outside the region used for printing on to the print medium and generally adjacent to a service station
140
in a conventional printer device.
The service station
140
is generally provided to maintain the health of the print heads
102
-
112
by providing a means for both cleaning and capping the nozzles
200
-
200
n
when the printer device is idle. The service station
140
typically includes a plurality of service station units
142
-
152
for performing servicing operations on the each of the print heads
102
-
112
. Generally, one service station unit
142
-
152
is provided for each of the print heads
102
-
112
. The service station units
142
-
152
are typically housed within a service station frame
154
. In use, the service station units
142
-
152
typically function as reservoirs to collect ink fired or “spitted” from a respective one of the print heads
102
-
112
to thus maintain each of the nozzles
200
-
200
n
in a functional state. In addition, each of the service station units
142
-
152
includes a device for capping the print heads
102
-
112
when the printer device is idle,
The drop detection module
130
generally operates to detect whether ink is properly fired from each of the nozzles
200
-
200
n
of each of the print heads
102
-
112
by detecting whether a beam of light is broken by an ink droplet. In
FIG. 3
, there is illustrated schematically a conventional drop detection module
130
used in a printer device. As seen in
FIG. 3
, the conventional drop detection module
130
generally includes a light emitting diode (LED)
302
, a lens
304
, a light receiving diode
306
, a drop detection unit
308
, and an amplifier
312
. To detect whether a nozzle is operating properly, a signal is sequentially sent to each nozzle to fire at least one ink droplet. If, in response to the signal, an ink droplet
300
is fired from one of the nozzles (e.g.,
202
), the ink droplet travels along a path
310
. The path
310
traced by the ink droplet
300
is configured to pass between the LED
302
and the light receiving photo diode
306
. The light emitted by the LED
302
is collimated by the lens
304
to produce a narrow light beam through which the ink droplet
300
may pass. The lens
304
may be integrally attached to the LED
302
or may constitute a separate element. The photo diode
306
detects the ink droplet
300
by detecting the disturbance in the light beam. In response to the light disruption in the light beam, the photo diode
306
produces a current which is amplified by an amplifier
312
and sent to the drop detection unit
308
, The drop detection unit
308
then determines whether the nozzle is operating properly.
The above-described process for determining whether a nozzle is functioning properly is repeated for each of the nozzles
200
-
200
n
on each of the print heads
102
-
112
. In order to test each of the nozzles
200
-
200
n
, the set of print heads
100
must be accurately positioned over the drop detection module
130
. Accordingly, each of the print heads
102
-
112
must be moved in the direction
170
sequentially over the drop detection module
130
. More particularly, each row of nozzles on each of the print heads
102
-
112
must moved to a position directly over the light beam for an accurate measurement to be obtained. By virtue of the numerous movements required to position each of the nozzles, the potential for misalignment between the nozzle to be tested and the light beam emitted from the LED
302
is relatively large. Additionally, the amount of time required to maneuver each of the rows of nozzles over the light beam for accurate testing thereof is also relatively large. This may be problematic because the time required to test each of the nozzles may sometimes exceed the amount of time allowed for each of the nozzles to be uncapped (e.g., on the order of about one second). Because of this possibility, in certain instances, it may be necessary to maneuver the set of print heads
100
over the service station
140
to thus perform servicing operations on the print heads
102
-
112
(e.g., “spit” ink out of some of the nozzles into respective service station units
142
-
1

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