Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1997-11-12
2001-08-21
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S092000, C347S017000, C347S085000
Reexamination Certificate
active
06276790
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to heaters that heat a print head of a hot melt ink jet printer.
2. Description of Related Art
A hot melt ink Jet printer (hereinafter referred to as “a printer”) includes a print head mounted on a carriage. The print head includes a heating tank, an ink tank, a plurality of nozzle heads, and heaters for heating these components. A hot melt ink (hereinafter referred to as an “ink”) is in its solid state at a normal temperature and changes to its liquid state when heated. Solid ink supplied to the heating tank is heated, melted, and supplied to the ink tank and further to the nozzle head. The ink in the ink tank and the nozzle head is maintained in its liquid state. Each of the nozzle heads includes a piezoelectric member forming an ink channel. When applied with a voltage, the piezoelectric member is deformed, thereby changing the internal pressure of the ink channel. As a result, ink in the ink channel is ejected as an ink droplet toward a printing medium.
When the printer is powered OFF after printing operation, ink remaining in the ink tank and the nozzle heads is cooled off and solidified while trapping air bubbles. Therefore, before starting the printing operation next time, a preparatory operation is required. That is, the solidified ink in the ink tank and the nozzle heads is melted. Also, the air bubbles are removed from the ink.
As shown in a graph in
FIG. 1
, both a heater and a nozzle head, that is, ink in the nozzle head, are at a normal temperature when a printer is powered ON. The heater starts generating heat and keeps increasing its temperature, and then, is leveled off at a predetermined temperature, which is slightly higher than an ink maintained temperature. Also, the heater heats up the ink to melt at the same time. However, the temperature increasing rate of the ink is lower than that of the heater. Then, the melted ink is maintained at the ink maintained temperature, for example, 120° C., in the liquid state. Then, the air bubbles are removed from the ink by a purging operation. In this way, the printer is set ready for the printing operation.
However, it may take a long time for the heater to heat up ink to the ink maintained temperature. Also, ink in different locations within the print head cannot increase its temperature at a uniform speed. For example, the nozzle head takes a longer time duration to reach the predetermined temperature than the ink tank.
SUMMARY OF THE INVENTION
It is the objective of the present invention to solve the above-described problems and to provide heaters capable of heating and melting hot melt ink at a high speed.
Those and other objects of the present invention will be attained by a head including an ink tank, a nozzle head that ejects ink, a front panel, a first detecting device, a second detecting device, a first tank heater, a second tank heater, a first panel heater, a second panel heater, ink tank heater control means, and panel heater control means. The ink tank stores ink and is formed with a first chamber, a second chamber, and a first channel connecting between the first chamber and the second chamber. The nozzle head is mounted on the front panel. The front panel is formed with a second channel connecting between the first chamber and the nozzle head and a third channel connecting between the nozzle head and the second chamber so that ink can flow from the first chamber into the second chamber via the second channel, the nozzle head, and the third channel. The first detecting device detects a temperature of the ink tank. The second detecting device detects a temperature of the front panel. The first tank heater heats and maintains the ink tank at a first predetermined temperature. The second tank heater heats the ink tank. The first panel heater heats and maintains the front panel at a second predetermined temperature. The second panel heater heats the front panel. The ink tank heater control means is connected to the first detecting device and controls the first tank heater and the second tank heater. The panel heater control means is connected to the second detecting device and controls the first panel heater and the second panel heater. After the printer is powered ON, the ink tank heater control means starts driving the first tank heater and the second tank heater for a first predetermined time duration, and the front panel heater control means starts driving the first panel heater and the second panel heater for a second predetermined time duration.
In another aspect of the present invention, there is provided a head including an ink tank, a nozzle head that ejects ink, a front panel, a first detecting device, a second detecting device, a first tank heater, a first panel heater, ink tank heater control means, panel heater control means, and purging means. The ink tank stores ink and is formed with a first chamber, a second chamber, and a first channel connecting between the first chamber and the second chamber. The front panel mounts the nozzle head and is formed with a second channel connecting between the first chamber and the nozzle head and a third channel connecting between the nozzle head and the second chamber so that ink can flow from the first chamber into the second chamber via the second channel, the nozzle head, and the third channel. The first detecting device detects a temperature of the ink tank. The second detecting device detects a temperature of the front panel. The first tank heater heats and maintains the ink tank at a first predetermined temperature. The first panel heater heats and maintains the front panel at a second predetermined temperature. The ink tank heater control means is connected to the first detecting device and controls the first tank heater. The panel heater control means is connected to the second detecting device and controls the first panel heater. The purging means executes a purging operation during which ink is circulated from the first chamber to the second chamber through the second channel, the nozzle head, and the third channel. The purging means executes the purging operation before the front panel reaches the second predetermined temperature after the ink tank has reached the first predetermined temperature.
In still another aspect of the present invention, there is provided a purging method including the steps of turning ON a first tank heater, a second tank heater, a first panel heater, and a second panel heater, detecting a temperature of an ink tank, turning OFF the second tank heater when the ink tank has reached a first predetermined temperature, executing a purging operation for circulating ink from a sub chamber of the ink tank to a main chamber of the ink tank via a nozzle head, detecting a temperature of a front panel, and turning OFF the second panel heater when the front panel has reached a second predetermined temperature.
REFERENCES:
patent: 4342042 (1982-07-01), Cruz-Uribe et al.
patent: 4357617 (1982-11-01), Shimazawa et al.
patent: 5392065 (1995-02-01), Suzuki
patent: 5424767 (1995-06-01), Alavizadeh et al.
patent: 5489925 (1996-02-01), Brooks et al.
patent: 5621444 (1997-04-01), Beeson
patent: 0 780 233 A2 (1997-06-01), None
Barlow John
Brother Kogyo Kabushiki Kaisha
Oliff & Berridg,e PLC
Stewart Jr. Charles W.
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