Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1998-06-19
2001-01-09
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06170931
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet heater chip module adapted to be secured to an ink-filled container.
BACKGROUND OF THE INVENTION
Drop-on-demand ink jet printers use thermal energy to produce a vapor bubble in an ink-filled chamber to expel a droplet. A thermal energy generator or heating element, usually a resistor, is located in the chamber on a heater chip near a discharge nozzle. A plurality of chambers, each provided with a single heating element, are provided in the printer's printhead. The printhead typically comprises the heater chip and a nozzle plate having a plurality of the discharge nozzles formed therein. The printhead forms part of an ink jet print cartridge which also comprises an ink-filled container.
A plurality of dots comprising a swath of printed data are printed as the ink jet print cartridge makes a single scan across a print medium, such as a sheet of paper. The data swath has a given length and width. The length of the data swath, which extends transversely to the scan direction, is determined by the size of the heater chip.
Printer manufacturers are constantly searching for techniques which may be used to improve printing speed. One possible solution involves using larger heater chips. Larger heater chips, however, are costly to manufacture. Heater chips are typically formed on a silicon wafer having a generally circular shape. As the normally rectangular heater chips get larger, less of the silicon wafer can be utilized in making heater chips. Further, as heater chip size increases, the likelihood that a chip will have a defective heating element, conductor or other element formed thereon also increases. Thus, manufacturing yields decrease as heater chip size increases.
Accordingly, there is a need for an improved printhead or printhead assembly which allows for increased printing speed yet is capable of being manufactured in an economical manner.
SUMMARY OF THE INVENTION
In accordance with the present invention, a heater chip module is provided comprising a rigid carrier, a nozzle plate and a heater chip. The carrier is adapted to be secured to a container for receiving ink. The carrier includes an opening extending completely through the carrier. The opening has an outer periphery. A nozzle plate is coupled to the carrier and extends out beyond the outer periphery of the opening so as to substantially cover the opening. A heater chip is positioned within the opening and is coupled directly to the nozzle plate. The heater chip is coupled to the carrier only by way of the nozzle plate. Further, the heater chip does not directly contact the carrier.
Two or more heater chips, aligned end to end or at an angle to one another, may be coupled to a single carrier via one or two or more nozzle plates. Thus, two or more smaller heater chips can be combined to create the effect of a single, larger heater chip. That is, two or more smaller heater chips can create a data swath that is essentially equivalent to one printed by a substantially larger heater chip.
Preferably, the carrier is formed from a ceramic material. Because the ceramic carrier does not expand or contract significantly in response to temperature or humidity changes experienced during printing, the spacing between adjacent heater chips coupled to a single carrier does not vary significantly. Further, because“good” chips, i.e., chips which have passed quality control testing, are assembled to the carrier, higher manufacturing yields are achieved.
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Anderson Frank Edward
Murthy Ashok
Barlow John
Brady John A.
Lemark International, Inc.
Stewart Jr. Charles W.
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