Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-06-17
2003-02-25
Hallacher, Craig (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S040000
Reexamination Certificate
active
06523934
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to inkjet printers. More specifically, the present invention relates to inkjet printers that are commonly used in large-scale, industrial printing applications. Such applications include, without limitation, printing bar codes, envelopes, labels and checks.
A typical thermal inkjet printer includes at least one printhead. Each printhead includes one or two columns of vertically-oriented nozzles. Each nozzle ejects a color ink dot when thermally actuated. During a printing operation, a sheet is moved along a paper flow axis. Each printhead may be scanned across the sheet along a scan axis. As each printhead is scanned across the sheet, it can lay down a swath of ink dots. A b/w printhead can lay down swaths of black dots; and a typical tri-color printhead can lay down swaths of cyan, magenta and yellow dots.
High printing speed is desirable, especially for large print jobs. However, printing speed is limited by several factors. All of the nozzles in a column are not fired simultaneously because firing a column of nozzles simultaneously would result in high power consumption. Firing a column of nozzles simultaneously would also “starve” the nozzle fluid chamber. To reduce power consumption and avoid fluid problems, the nozzles are usually fired sequentially through small subgroups called “primitives.” Within each primitive, the nozzles are fired in succession, from a first nozzle to a last nozzle.
Firing frequency of the nozzles limits the speed at which the printhead is scanned across a sheet. If the scan speed is increased beyond a limit, printing a vertical line becomes difficult because the nozzles move past the vertical line before they can be fired. Without compensation for scan speed, the line will be twisted.
It would be desirable to increase the speed at which the printhead is scanned, especially for large-scale, industrial printing applications. Increasing the scan speed would reduce printing time.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a printer includes a printhead stall rotatable about a Z-axis; a mechanism for rotating the printhead stall about the Z-axis; and a controller for controlling the mechanism to change slant angle of the printhead stall as a function of primitive spacing.
REFERENCES:
patent: 5359355 (1994-10-01), Nagoshi et al.
patent: 5924804 (1999-07-01), Hino et al.
patent: 6003969 (1999-12-01), Freret, Jr.
patent: 6092887 (2000-07-01), Tanino et al.
Beauchamp Robert W.
Klausbruckner Michael J.
Hallacher Craig
Hewlett--Packard Company
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