Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-12-28
2001-04-17
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06217163
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of digitally controlled printing devices, and in particular to continuous ink jet print heads which integrate multiple nozzles on a single substrate and in which the breakup of a liquid ink stream into droplets is caused by a periodic disturbance of the liquid ink stream.
BACKGROUND OF THE INVENTION
Many different types of digitally controlled printing systems have been invented, and many types are currently in production. These printing systems use a variety of actuation mechanisms, a variety of marking materials, and a variety of recording media. Examples of digital printing systems in current use include: laser electrophotographic printers; LED electrophotographic printers; dot matrix impact printers; thermal paper printers; film recorders; thermal wax printers; dye diffusion thermal transfer printers; and ink jet printers. However, at present, such electronic printing systems have not significantly replaced mechanical printing presses, even though this conventional method requires very expensive setup and is seldom commercially viable unless a few thousand copies of a particular page are to be printed. Thus, there is a need for improved digitally controlled printing systems, for example, being able to produce high quality color images at a high-speed and low cost, using standard paper.
Ink jet printing has become recognized as a prominent contender in the digitally controlled, electronic printing arena because, e.g., of its non-impact, low-noise characteristics, its use of plain paper and its avoidance of toner transfers and fixing. Ink jet printing mechanisms can be categorized as either continuous ink jet or drop on demand ink jet. Continuous ink jet printing dates back to at least 1929. See U.S. Pat. No. 1,941,001 to Hansell.
Conventional continuous ink jet utilizes electrostatic charging tunnels that are placed close to the point where the drops are formed in a stream. In this manner individual drops may be charged. The charged drops may be deflected downstream by the presence of deflector plates that have a large potential difference between them. A gutter (sometimes referred to as a “catcher”) may be used to intercept the charged drops, while the uncharged drops are free to strike the recording medium. U.S. Pat. No. 3,878,519, which issued to Eaton in 1974, discloses a method and apparatus for synchronizing droplet formation in a liquid stream using electrostatic deflection by a charging tunnel and deflection plates.
U.K. Patent Application GB 2 041 831A discloses a mechanism in which a deflector steers an ink jet by the Coanda (wall attachment) effect. The degree of deflection can be varied by moving the position of the deflector or by changing the amplitude of perturbations in the jet.
In commonly assigned, co-pending U.S. patent application Ser. No. 08/954,317 entitled CONTINUOUS INK JET PRINTER WITH ASYMMETRIC HEATING DROP DEFLECTION filed in the names of Chwalek, Jeanmaire, and Anagnostopoulos on Oct. 17, 1997, now U.S. Pat. No. 6,079,821, an ink jet printer includes a delivery channel for pressurized ink to establish a continuous flow of ink in a stream flowing from a nozzle bore. A heater having a selectively-actuated section associated with only a portion of the nozzle bore perimeter causes the stream to break up into a plurality of droplets at a position spaced from the heater. Actuation of the heater section produces an asymmetric application of heat to the stream to control the direction of the stream between a print direction and a non-print direction.
It was also disclosed in the above-cited co-pending application that, using semiconductor VLSI fabrication processes and equipment, and by incorporating addressing and driving circuits on the same silicon substrate as the nozzles, a dense linear array of nozzles can be produced. Such arrays can be many inches long and contain thousands of nozzles, thus eliminating the need to scan the print head across the page. In addition, ink jet printers may contain multiple arrays, all of which may be located on the same silicon substrate. Each array could then emit a different color ink. Full width and full color ink jet printers can thus be manufactured, which can print at high speeds and produce high quality color prints.
DISCLOSURE OF THE INVENTION
In graphic arts printing systems it is required that the droplets land extremely accurately on the specified locations, because of the high quality images expected from such systems. Many factors influence drop placement, such as air turbulence or non-uniform air currents between the print head and the receiver, varying resistance of the heaters or other manufacturing defects that affect droplet deflection.
It is therefore desirable to compensate for droplet placement errors. Such methods may include elimination of turbulence and more uniform air currents, higher velocity drops, more uniform heater resistance, etc.
Accordingly, it is a feature of the present invention to provide apparatus for controlling ink in a continuous ink jet printer including an ink delivery channel; a nozzle bore which opens into the ink delivery channel to establish a continuous flow of ink in a stream; a heater having a plurality of selectively independently actuated sections which are positioned along respectively different portions of the nozzle bore's perimeter. An actuator selectively activates none, one, or a plurality of the heater sections such that: actuation of heater sections associated with only a portion of the entire nozzle bore perimeter produces an asymmetric application of heat to the stream to control the direction of the stream between a print direction and a non-print direction, and simultaneous actuation of different numbers of heater sections associated with only a portion of the entire nozzle bore perimeter produces corresponding different asymmetric application of heat to the stream to thereby control the direction of the stream between one print direction and another print direction.
It is another feature of the present invention to provide a print head having an actuator adapted to selectively activate the heater sections such that the stream is selectively directed: in a non-print direction, in a first print direction, in a second print direction, and in a third print direction between the first and second print directions.
It is another feature of the present invention to provide a print head wherein the heater has three selectively independently actuated sections which are positioned along respectively left, center, and right portions of the nozzle bore perimeter, and the actuator is adapted to selectively activate no heater section, the left and center heater sections simultaneously, the center heater section alone, and the center and right heater sections simultaneously such that: actuation of no heater section directs the stream in the non-print direction, simultaneous actuation of the left and center heater sections directs the stream in the first print direction, simultaneous actuation of the center and right heater sections directs the stream in the second print direction, and actuation of the center heater section alone directs the stream in the third print direction between the first and second print directions.
It is another feature of the present invention to provide a print head having a plurality of nozzle bores, the nozzle bores being spaced apart from left to right in accordance with the predetermined resolution. Each nozzle bore has a heater having selectively independently actuated sections which are positioned along the nozzle bore perimeter; and an actuator adapted to selectively activate the heater sections such that the stream from a given nozzle bore is selectively directed: in a non-print direction, in a first print direction to produce a spot on the receiver aligned with the nozzle bore adjacent to one side of the given nozzle bore, in a second print direction to produce a spot on the receiver aligned with the nozzle bore adjacent to the other side of the given nozzle bo
Anagnostopoulos Constantine N.
Chwalek James M.
Hawkins Gilbert A.
Eastman Kodak Company
Le N.
Nguyen Judy
Sales Milton S.
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