Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2000-07-14
2001-10-09
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S019000
Reexamination Certificate
active
06299273
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet printhead, and, more particularly, to a method and apparatus for thermal control of an ink jet printhead.
2. Description of the Related Art
In an ink jet printer, the drop and mass of the ink are dependent upon the temperature of the head. If the temperature of the head varies significantly from swath to swath, then a color shift will become visible, a phenomenon which is referred to as “banding.” In order to overcome this problem, ink jet printers typically add heat to the print chips by the use of substrate heaters. It is known for a print chip of an inkjet printer to be attached to a plastic support. Such plastic supports typically do not remove heat from the print chip in an efficient manner and therefore the ability to print dense areas on the page is thermally limited.
In order to provide a better path for heat to escape to the ambient air, it is also known for print chips to be attached to a metal body or heatsink. By attaching the print chip to a metal heatsink, swings in chip temperature are reduced. However, the use of a metal heatsink significantly affects the thermal control of the print chip.
As ink jet printers begin to move into the business market, it becomes necessary to manage the printhead in a more efficient manner. The use of print chips attached to heatsinks for use in an inkjet printer requires improvements to the known print chip temperature control methods. What is needed in the art is a method of more accurately controlling the temperature of a print chip.
SUMMARY OF THE INVENTION
The present invention provides a method of storing thermal characteristics of a print chip in a memory attached to the printhead, and using the thermal information to select a level of substrate heater power in order to more uniformly control the chip temperature. Variations in the mounting of the print chips are overcome through the use of calibration techniques. By using the thermal information stored in the memory, calibration is significantly improved, resulting in a printer that is better suited for business applications.
The invention comprises, in one form thereof, a method of controlling a temperature of a print chip of a printhead in an ink jet printer. The printer is provided with a memory device. The print chip is provided with and at least one ink-jetting resistor. The printhead is provided with at least one substrate heater and a heatsink attached to the print chip. Power is applied to the substrate heater and/or the inkjetting resistor. Temperature data associated with the print chip is recorded during the applying step. A thermal resistance value of the print chip to the heatsink and/or a thermal capacitance value associated with the printhead is calculated dependent upon the recorded temperature data. The thermal resistance value of the print chip to the heatsink and/or the thermal capacitance value associated with the printhead are stored in the memory device. A temperature of the heatsink is measured based upon the thermal resistance value of the print chip to the heatsink, the thermal capacitance value associated with the printhead, a temperature of the print chip, an ambient temperature, and/or a thermal resistance value associated with the heatsink. A level of power to be applied to the substrate heater is set dependent upon the thermal resistance value of the print chip to the heatsink and/or the thermal capacitance value associated with the printhead, and the temperature of the heatsink.
The invention comprises, in another form thereof, an ink jet printer including a printhead having a substrate heater, a print chip, and a heatsink attached to the print chip. A memory device stores a thermal resistance value of the print chip to the heatsink. A controller retrieves the thermal resistance value from the memory device and sets a level of power to be applied to the substrate heater dependent upon a temperature of the heatsink and the thermal resistance value of the print chip to the heatsink
An advantage of the present invention is that the temperature of the print chip can be more uniformly controlled.
Another advantage is that the temperature of the print chip can be more accurately predicted.
Yet another advantage is that the temperature of the print chip can be more reliably prevented from exceeding a predetermined limit temperature.
REFERENCES:
patent: 4536774 (1985-08-01), Inui et al.
patent: 4791435 (1988-12-01), Smith et al.
patent: 4872028 (1989-10-01), Lloyd
patent: 4980702 (1990-12-01), Kneezel et al.
patent: 5036337 (1991-07-01), Rezanka
patent: 5107276 (1992-04-01), Kneezel et al.
patent: 5168284 (1992-12-01), Yeung
patent: 5300969 (1994-04-01), Miura et al.
patent: 5315316 (1994-05-01), Khormaee
patent: 5745132 (1998-04-01), Hirabayashi et al.
patent: 5815173 (1998-09-01), Silverbrook
patent: 5841452 (1998-11-01), Silverbrook
patent: 5877785 (1999-03-01), Iwasaki et al.
patent: 5907331 (1999-05-01), Markham
patent: 5986684 (1999-11-01), Ohashi
patent: 6019449 (2000-02-01), Bullock et al.
patent: 6019457 (2000-02-01), Silverbrook
patent: 0872345A2 (1998-10-01), None
patent: 63-276563 (1988-11-01), None
Anderson Frank Edward
Dyer Stanley
Jones Christopher Dane
Mulay Shirish Padmaker
Spencer William Shannon
Le N.
Lexmark International Inc.
Nghiem Michael P.
Taylor & Aust P.C.
LandOfFree
Method and apparatus for thermal control of an ink jet... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for thermal control of an ink jet..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for thermal control of an ink jet... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2603122