International Business Machines Corporation

Demetrios Troupes

Randall W Alexander

Phuc Ky Do

Carol E Wyke

Tim V Angst

Dennis R Hedrick

Nicholas J Krull

Mark E Bunke

Barnes R Kendrick, Jr

A printer in which the heat build-up in the printhead is limited by determining whether the printhead temperature is at its temperature threshold. If so, the printing is not allowed to proceed untilt the printhead has cooled sufficiently so that the printing will not cause it to exceed its temperature threshold. The temperature limiting feature is accomplished by testing before each unit of printing whether the temperature of the printhead is below the threshold and therefore printing may occur as usual or whether to take some action to limit the temperature, analyzing the activity during each time period to determine whether heating or cooling of the printhead is occurring, and adjusting the present (calculated) temperature of the printhead accordingly. In the preferred embodiment, the temperature calculation is stored in memory and initialized at the threshold initially, then if no printing occurs during a given period, cooling of a given portion of the assumed temperature (accomplished by shifting a binary representation by a given number of bits) is accomplished. If during any period printing has occurred, the amount of printing in terms of number of print elements actuated is multiplied by a heat factor per print element actuated which is added to the temperature. In some instances, both heating and cooling can occur and are netted out with the temperature being adjusted by the difference.

Temperature limiting apparatus and method for printer

Through-put of a printer is increased by optimizing the print head's movement between print lines. Optimization is performed on a time basis rather than a distance basis. A determination is made as to whether it is quicker to position the print head at the left or right end position of the next print line. The calculations account for current print head position, the relative end positions of the next print line, the length of the next print line, current print head speed, the various acceleration and deceleration times and the turn-around settling time for the print head.

Printer with enhanced bidirectional logic seeking for increased

A method and apparatus for quieting the operation of a dot matrix printer by logically dividing the data to be printed among timed spaced printing passes is disclosed. A matrix of data to be printed is stored in a memory. A slice of data is selected from the stored data and the number of dots to be printed simultaneously is reduced by logically allocating the data in each slice among complementary submatrices. Each submatrix of data is printed substantially aligned with each other submatrix in two passes of the print head across the print medium to represent the entire selected slice of data. Noise reduction is achieved by reducing the number of data dots simultaneously printed at each print location.

Method and apparatus for quieting the operation of a dot matrix printer

A method and apparatus for displaying enlarged or enhanced dot matrix characters is disclosed. Using stored sets of binary data elements which define the shape of the respective characters of a set, logical operations are performed to add additional binary data elements to provide the desired enlarged character. Characters may be enlarged in the vertical and horizontal directions by lengthening the horizontal, vertical, and diagonal linear components which together comprise the character. Characters may also be enhanced by thickening the linear components thereof in a direction orthogonal to that of the linear components, and made more dense with additional dots along the length of the linear components. The stored data defines the character with a high density in the horizontal direction and a lower density in the vertical and diagonal directions. The characters are enlarged, and enhanced, by defining a reference matrix which comprises a subset of the stored binary data elements, expanding the reference matrix by adding blank binary data elements to the defined reference matrix at locations between the stored binary data elements, and comparing portions of the expanded reference matrix with corresponding portions of a predetermined matrix, and converting to a dot those added binary data elements that match the elements of the predetermined matrix. Characters may be differentially enlarged, or enhanced in one manner but not another, or they may be thickened toward the middle of each character.

Method and apparatus for displaying enlarged or enhanced dot matrix

A method and apparatus for displaying enhanced dot matrix characters is disclosed. Using stored sets of binary data elements which define the shape of the respective characters of a set, logical operations are performed to add additional binary data elements to provide the desired character. Characters are enhanced by either thickening the linear components thereof in a direction orthogonal to that of the linear components, or making them more dense by adding dots along the length of the linear components, or both. The stored data defines the character with a high density in the horizontal direction and a lower density in the vertical and diagonal directions. The characters are enhanced by defining a reference matrix which comprises a subset of the stored binary data elements, adding blank binary data elements to the defined reference matrix at locations between the stored binary data elements, and comparing portions of the reference matrix including the added blank binary data elements with corresponding portions of a predetermined matrix, and converting to a dot those added binary data elements that match the elements of the predetermined matrix. Characters may be enhanced in one manner but not another, and they may be enhanced along one or more linear components but less than all of them.

Method and apparatus for displaying enhanced dot matrix characters

Where the ribbon advance mechanism of a printer is driven by the motion of the print head carrier, ink in the ribbon will be differentially depleted depending upon the density of print. This varied depletion becomes a problem for printers capable of printing high density graphics images, particularly color filled images. In accordance with this invention, the printing density is monitored and when the printing density exceeds a predetermined value, the print head is caused to be moved an amount greater than that necessary to position the print head at a succeeding print position so as to thereby cause additional ink ribbon to be advanced and to avoid overprinting on areas of the ribbon where high density printing has occurred.

Ribbon feed with ink depletion compensation

A printer prints characters by printing selected character elements in a matrix of print positions arranged in horizontal rows and vertical columns. The printer includes storage means for storing sets of character data elements which are used for printing the character elements. The printer also includes logic means for selectively performing logical operations on the sets of character data elements in order to vary the sets of character data elements in accordance with certain rules and thereby vary the print quality in the horizontal, vertical and diagonal directions of the characters which will be printed using the stored character data elements. The stored sets of character data elements are selected so that they can be used for printing characters which have a high print quality in the horizontal direction and a low print quality in the vertical and diagonal directions. In order to print characters in a low print quality the logic means derives subsets of the stored sets of character data elements and only these subsets of character data elements are used for printing characters. In order to print characters in a high print quality the logic means performs logical operations on the stored sets of character data elements so as to generate additional character data elements. These additional character data elements together with the stored character data elements are used for printing characters.

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Charlotte, NC, United States of America

Demetrios Troupes