Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-06-19
2001-07-31
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S063000, C347S058000, C347S059000
Reexamination Certificate
active
06267472
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 carrier adapted to be secured directly to an ink-filled container, at least one heater chip having a base coupled to the carrier, and at least one nozzle plate coupled to the heater chip. The carrier includes inner side walls and a support section which together define an inner cavity. An edge feed heater chip is coupled to the carrier support section. The heater chip includes side walls. The support section includes first and second passages which define first and second paths for ink to travel from the container to the inner cavity. The inner cavity and the heater chip are sized such that a first side wall of the heater chip is spaced from a first inner side wall of the carrier and a second side wall of the heater chip is spaced from a second inner side wall of the carrier. A nozzle plate is coupled to the heater chip and the carrier. The nozzle plate has a width such that the nozzle plate extends over an outer surface of the carrier. Sealant material is provided in the inner cavity such that at least a portion of the first inner side wall of the carrier, at least a portion of the first side wall of the heater chip, a first section of the nozzle plate and the sealant material define a first sealed ink cavity for receiving ink passing through the first passage. Additional sealant material is provided in the inner cavity such that at least a portion of the second inner side wall of the carrier, at least a portion of the second side wall of the heater chip, a second section of the nozzle plate and the additional sealant material define a second sealed ink cavity for receiving ink passing through the second passage.
A flexible circuit is coupled to the heater chip such as by wire bonding or TAB bonding.
Two or more heater chips, positioned end to end or offset from one another, may be secured to a single carrier. 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.
Each of two or more heater chips coupled to a single carrier may be dedicated to a different color. For example, three heater chips positioned side by side may be coupled to a single carrier, wherein each heater chip receives ink of one of the three primary colors.
The inner cavity has a first length, the heater chip has a second length and the nozzle plate has a third length. Preferably, the third length of the nozzle plate is less than the first length of the inner cavity. More preferably, the third length of the nozzle plate is approximately equal to or less than the second length of the heater chip. If the nozzle plate has a length that exceeds that of the heater chip, wires coupling traces on the flexible circuit to bond pads on the heater chip must extend through windows or openings provided in the nozzle plate. If, however, the nozzle plate does not extend beyond the bond pads on the heater chip, the wires coupling the traces to the bond pads do not have to extend through windows formed in the nozzle plate. Consequently, the flexible circuit can extend very close to the bond pads on the heater chip and the wires can be made shorter. The shorter wire length is advantageous as it results in more reliable bonds, a lower likelihood of contact between adjacent wires, lower wire loop height, and lower encapsulant bead height. Bead height is important as the distance between the printhead and the paper needs to be at a minimum to ensure optimum dot placement accuracy and to prevent the encapsulant bead from touching cockled paper. Further, nozzle plate manufacture is simplified as wire-receiving windows do not have to be formed in the nozzle plate.
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Maher Colin Geoffrey
Murthy Ashok
Oliver Darrin Wayne
Saldanha Singh Jeanne Marie
Samples Robert Allen
Barlow John
Lexmark International Inc.
Shah Manish
Showalter Robert L.
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