Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-04-16
2004-03-09
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000, C347S030000
Reexamination Certificate
active
06702424
ABSTRACT:
This application is based on Japanese Patent Applications Nos. 2001-118743, 2001-118745, and 2001-118746, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a head jetting property maintenance device for maintaining an ink jetting property of a recording head for jetting ink droplets to a recording medium inconstant performance and a recording apparatus with the head jetting property maintenance device.
Generally, an ink jet printer as one form of the recording apparatus is constructed with a printing head mounted on a carriage, which reciprocates in the main scan direction, and a recording medium feeding device for intermittently feeding the recording medium, such as a printing sheet of paper, step by step at a predetermined amount in the sub-scan direction. In operation, the printer moves the printing head in the main scan direction while feeding the recording medium in the sub-scan direction. At the same time, the printer jets ink droplets from the printing head to the recording medium.
Normally, in the mono-color ink jet printer, one printing head is mounted on the carriage. As for the full color ink jet printers, some are provided with a black printing head for jetting black ink and a plurality of color printing heads for jetting color inks of necessary colors, such as yellow, cyan, and magenta, mounted on the carriage, and the others are provided with one printing head capable of jetting color inks of necessary colors, such as black, yellow, cyan and magenta, mounted on the carriage.
The printing head of the ink jet printer thus constructed includes pressure generating chambers and nozzle orifices communicating to the pressure generating chambers. By pressurizing the pressure generating chamber where ink is stored at a predetermined pressure, an ink droplet of controlled size is jetted to the recording medium from the nozzle orifice associated with the pressurized chamber. Accordingly, when the ink jetting property of the printing head at the nozzle orifice varies, the property variation greatly affects the quality of the recorded or printed image. To avoid this, it is essential to maintain the ink jetting property in constant performance.
The ink jetting property is varied by various causes: viscosity increase of ink due to evaporation and drying of the ink component at the nozzle orifices, clogging of the nozzle orifices by solid matters, dust sticking, air bubble entering, and others. To cope with this, the ink jet printer is equipped with a head jetting property maintenance device which removes the factors for causing the property variation to maintain the ink jetting property in constant performance.
The head jetting property maintenance device includes a capping device, a suction pump and a wiping device. The capping device is configured so as to seal the nozzle forming surface of the printing head in a non-print mode of the printer to isolate the nozzle orifices from outside. The capping device has functions to suppress the evaporation and drying of the ink and thus to suppress the viscosity increase and solidification of the ink. While the nozzle forming surface is sealed with the capping device, it is impossible to completely prevent the clogging of the nozzle orifices by solid materials and the entering of air bubbles into the ink passage. Accordingly, to completely remove the clogging and bubble entering problems, the suction pump is provided.
The suction pump applies a negative pressure to the nozzle orifices in a state that the capping device seals the nozzle forming surface. Under the negative pressure applied, ink is forcibly discharged from the nozzle orifices thereby removing solid materials and air bubbles. Usually, the operation of forcibly sucking and discharging the ink by the suction pump is carried out when the ink jet printer is stopped for a long time and is operated again, and when the user finds the quality deterioration of the printed image, and operates a dedicated switch on the operation panel.
When the discharging operation by forcible suction of the suction pump is carried out, ink often sticks to the nozzle forming surface of the print head, and the turbulence of the meniscus often occurs. Further, foreign materials tend to stick to the nozzle forming surface of the printing head with time. To remove the foreign materials, the wiping device is provided to wipe the nozzle forming surface according to the necessity.
The wiping device includes a wiping member which is formed with an elastic plate made of rubber or the like, and is clamped at the base end with a holder. The wiping device is configured so that the edge part of the top end of the wiping member is elastically pressed against and reciprocatively moved on the nozzle forming surface, thereby cleaning the nozzle forming surface. The wiping device has a function to regulate the meniscuses of ink at the nozzle orifices, viz., to stabilize the same, in addition to the function of wiping off the ink and the foreign materials sticking to the nozzle forming surface.
In a conventional head jetting property maintenance device, as described in Japanese patent Publication No. JP-A-11-138830, the driving of the capping device and the wiping device is switched to and from the driving of the suction pump depending on the rotational direction of a motor as a drive source, by use of one planet gear.
FIG. 80
is a side view showing another conventional head jetting property maintenance device. As illustrated by (a) of the figure, in the head jetting property maintenance device, the capping device
1
and the wiping device
2
are mounted on a supporting part
3
which is rotatable and vertically movable, while being disposed angularly spaced by 90°. A partially toothless gear
4
is fastened to the supporting part
3
, and the supporting part
3
is disposed such that the partially toothless gear
4
comes in contact with the partially toothless cam
5
. The head jetting property maintenance device is provided with a suction pump (not shown).
With such a construction, in a non-print mode of the printer, to seal the nozzle forming surface of the printing head and to isolate it from outside, the head jetting property maintenance device, as shown in (a) of the figure, is set such that the supporting part
3
is positioned at the top part in a state that the capping device
1
is directed upward, by means of the partially toothless cam
5
.
When the nozzle forming surface is wiped after the printing in a manner that the edge part of the top end of the wiping member is elastically pressed against the nozzle forming surface and reciprocatively moved thereon, the partially toothless cam
5
is turned to bring the teeth
5
a
of the partially toothless cam
5
into engagement with the teeth
4
a
, and turns the supporting part
3
together with the partially toothless gear
4
. Finally, as shown in (c) of the figure, the supporting part
3
is set such that the supporting part
3
is positioned at the lower-most part in a state that the wiping device
2
is directed upward, by means of the partially toothless cam
5
.
In the former related art, the vertical movement of the cap and the reciprocal movement of the wiper are performed based on the unidirectional rotation of the motor. Accordingly, it is impossible to initialize the positions of the cap and the wiper. For this reason, it is necessary that flags to detect the initializing positions of the cap and wiper are provided on cams for driving the cap and the wiper thereby effecting sensing them. Accordingly, the sensors are essentially needed, and the assembling and adjustment of the device are complicated. The cost to manufacture the device is increased.
Further, the pump is also driven to turn in only one direction. Therefore, particularly when the tube pump is used, it is impossible to release the pulley from the tube. There is a fear that the pulley is left pressing the tube. To avoid this, it is necessary to move the carriage and lock the planet gear, and then to release the pul
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