US 5,675,370 AGranted

Printhead having multiple print lines, and method and apparatus for using same

AssigneeIntermec Corporation

InventorsPixie A. Austin, Edward M. Millet, David S. Nierescher, Christopher A. Wiklof

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Abstract

A printhead having multiple print lines of conventional design and a printhead control system for using the multiple print lines in a variety of operations. In one embodiment, the printhead control system prints an image by superimposing the printing from multiple print lines. In another embodiment, the image is printed by alternating the energization of one print line so that each print line is used to print only 1/3 of the image lines. As a result, the print lines are allowed a relatively long time to cool, thus allowing the printhead to be operated at a faster speed. In another embodiment, the printing elements of each print line print with a different image density, and images printed by superimposing the printing elements in the print lines with a variety of combinations depending upon the desired magnitude of the image density. In still another embodiment of the printhead control system, the resistance of each printing element is checked and, if found to be unacceptably high, corresponding printing elements of other print lines are used for printing.

Claims16

Dependent claims

An apparatus for thermally printing on print media, comprising:

a substantially stationary printhead having a plurality of spaced apart, parallel print lines, each of said print lines including a plurality of substantially uniform in size, sequentially positioned printing elements which may be selectively energized to increase a temperature of an adjacent portion of said printhead;
and
a printhead controller operatively connected to said printhead, said printhead controller receiving data corresponding to a monochrome image to be printed on said print media, said printhead controller selectively applying heating signals to the printing elements in each of said print lines to thermally print a line of said image on said print media wherein said printhead data is stored in said memory in an N.times.M matrix where N is a number of scan line columns corresponding to a number of scan lines needed for said printhead to print said image on said print media, and M is a number of printing element rows corresponding to a number of printing elements in each print line of said printhead, and wherein said printhead contains an L amount of said print lines and said image is printed with S scan lines, L, M, and N being greater than one, and wherein, for each value of X from 1, which is closest to an entry point of said print media to said printhead, to L, which is furthest from the entry point of said print media to said printhead, and each value or N from 1 to S, said print media is advanced across said printhead a distance between adjacent print lines, and wherein said printhead controller loads said printhead data from said memory into said printhead with printhead data from scan line column (N-X+1) of said memory coupled to print line X of said printhead until each of S lines of said image has been printed thereby superimposing the printing from the L print lines of said printhead on said print media.

A method of printing on print media with a printhead having a plurality of spaced apart, parallel print lines, each of which include a plurality of sequentially positioned, substantially uniformly sized printing elements which may be selectively energized to increase the temperature of a portion of said printhead adjacent said selectively energized printing elements, said method comprising selectively and substantially simultaneously applying heating signals to the selectively energized, substantially uniformly sized printing elements in each of said print lines to thermally print a monochrome image on said print media wherein said printhead is substantially stationary and contains an L amount of said print lines and said image is printed with S scan lines, L being greater than one, and wherein, for each value of X from 1, which is a print line closest to an entry point of said media to said printhead, to L, which is a print line furthest from the entry point of said media to said printhead, and each value of N from 1 to S, said print media is advanced across said printhead the distance between adjacent print lines, and wherein said step of selectively applying said heating signals to the printing element in each of said print lines includes applying printhead data to said printhead with printhead data from a column (N-X+1) of a matrix of printhead data coupled to print line X of said printhead until each line of said monochrome image has been printed, thereby superimposing the printing from the L print lines of said printhead on said print media.

An apparatus for thermally printing on print media, comprising:

a printhead having N number of spaced apart, parallel print lines, N being greater than one, and each of the print lines including a plurality of sequentially positioned printing element of approximately similar construction which may be selectively energized to increase a temperature of a portion of the printhead;
and
a printhead controller operatively coupled to the printhead, the printhead controller receiving data corresponding to a monochrome image to be printed on the print media, the printhead controller selectively applying heating signals to the printing elements in each of the print lines to thermally print each line of the monochrome image on the print media, wherein the heating signals for each line of the image provide approximately 1/N of a desired power to each of the N number of print lines, and wherein the printhead controller provides a print media advance signal to advance the print media across the printhead to superimpose the printing of each of the N number of print lines of each line of the monochrome image.

Dependencies are inferred from the claim text.