Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1999-07-30
2001-06-19
Barlow, Jr., John E. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S065000
Reexamination Certificate
active
06247779
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally printers, and will be specifically disclosed as an improved printhead arrangement for ink jet printers.
BACKGROUND OF THE INVENTION
Thermal inkjet print cartridges operate by rapidly heating a small volume of ink to cause the ink to vaporize and be ejected through one of a plurality of orifices so as to print a dot of ink on a recording medium, such as a sheet of paper. Typically, the orifices are arranged in one or more linear arrays in a nozzle member. The properly sequenced ejection of ink from each orifice causes characters or other images to be printed upon the paper as the printhead is moved relative to the paper. The paper is typically shifted each time the printhead has moved across the paper. The thermal inkjet printer is fast and quiet, as only the ink strikes the paper. These printers produce high quality printing and can be made both compact and affordable.
An inkjet printhead generally includes: (1) ink channels to supply ink from an ink reservoir to each vaporization chamber proximate to an orifice; (2) a metal orifice plate or nozzle member in which the orifices are formed in the required pattern; and (3) a silicon substrate containing a series of thin film resistors, one resistor per vaporization chamber.
To print a single dot of ink, an electrical current from an external power supply is passed through a selected thin film resistor. The resistor is then heated, in turn superheating a thin layer of the adjacent ink within a vaporization chamber, causing explosive vaporization, and, consequently, causing a droplet of ink to be ejected through an associated orifice onto the paper.
A series of film resistors are generally grouped together into a single microcircuit or heater chip. Typically, the heater chip is mounted on a base or substrate. The ink reservoir is generally, but not necessarily always, located below the base and the heater chip is mounted on the top of the base. Ink channel configurations can vary widely, however, one desirable configuration uses an edge feed via. In an edge feed via configuration, the ink channels extend on one or more of the edges of the heater chip. For instance, one common edge feed via configuration has two ink channels, each one delivering ink to the length-wise edges of the heater chip. The heater chips are designed to operate at a particular range of temperatures. If a heater chip overheats, a variety of problems can result, such as nozzle failure, droplet misdirection, excessive droplet splatter, etc. Typically, as the print speeds increase, more heat is generated by the heater chips. To avoid overheating, it is desirable to transfer heat away from the heater chips. Generally, the outside of a printhead include a series of cooling fins to transfer heat from the printhead to the ambient air. However, in an edge feed via configuration, the ink channels act as insulators (due in part to the relatively low thermal conductivity of ink) preventing the heat transfer from the heater chip to the cooling fins. As such, it is desirable to improve the heat transfer characteristics in a printhead.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a printhead with improved heat removal characteristics. Additional objectives, advantages and novel features of the invention will be set forth in the description that follows and, in part, will become apparent to those skilled in the art upon examining or practicing the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
One aspect of the present invention is a printhead having an ink source, a body, and a mounting base. An ink heater is thermally coupled to the mounting base. A flowpath is defined at least in part by the mounting base and the body, and is used for delivering ink from the ink source to the ink heater. Three or more thermally conductive bridges extend from the mounting base to the body. Preferably, the printhead uses an edge feed via configuration, and one or more of the thermally conductive bridges spans the edge feed via.
Another aspect of the present invention is a printhead having an ink reservoir, a body, and a vaporization chamber including an orifice. An ink heater is provided for heating ink in the vaporization chamber to facilitate the ejection of the ink therein out through the orifice. An edge feed via is used for delivering ink from the ink reservoir to the vaporization chamber. One or more thermal bridges are positioned in the edge feed via and provide a conductive heat transfer path from the heater chip to the body. The thermal bridges have a thermal conductivity greater than thermal conductivity of the ink. Preferably, the body and thermal bridges are formed from a homogenous material such as aluminum.
Still other aspects of the present invention will become apparent to those skilled in the art from the following description of a preferred embodiment, which is by way of illustration, one of the best modes contemplated for carrying out the invention. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and descriptions are illustrative in nature and not restrictive.
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Lattuca Michael David
Mulay Shirish Padmakar
Nowell, Jr. Ronald Monroe
Raulinaitis Michael
Ward David Amos
Barlow Jr. John E.
Dinsmore & Shohl
Lexmark International Inc.
Stephens Juanita
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