Method and apparatus for enhancing and maintaining character quality in thermal printers
AssigneeHewlett-Packard Company
InventorAlbert W. Kovalick
Life of this patent
Estimating the term…
Abstract
The quality of thermally printed characters is enhanced by controlling the time at which and the time for which power is applied to the resistive printing elements in a battery-operated moving-head thermal dot matrix printer. By sequentially strobing the elements in the pattern of the character to be formed as the print head moves across thermal sensitive paper, a high-quality slanted character is printed and parasitic losses are reduced. By inversely varying the time power is supplied to each dot as battery voltage varies, character quality is maintained and useful battery life is extended.
Claims21
A printer for printing characters on a printing medium comprising:
- a printer head, having a plurality of spaced transducers mounted in a line thereon, movably mounted in close proximity to the printing medium, the line of transducers being oriented transverse to the direction of head movement;
- motive means coupled to the printer head for driving the printer head past the printing medium at a predetermined rate;
- timing means for producing timing signals;
- character generating means coupled to the timing means for generating character data signals in response to timing signals therefrom;
- slant generating means coupled to the timing means for generating periodic, sequentially-timed command signals at a preselected repetition rate in response to timing signals received therefrom;
- and
- gating means coupled to the printer head, the slant generating and the character generating means for selectively activating successive ones of the transducers in response to command and character data signals to print characters on the printing medium as a matrix of rows and columns of dots, the interval between rows being determined by the spacing between transducers and the interval between columns being determined by the repetition rate of the command signals and the rate at which the printer head is driven.
A method for printing characters on a printing medium comprising the steps of:
- supplying power;
- driving a printer head having a plurality of spaced transducers mounted in a line aligned thereon transverse to the direction of head movement past the printing medium in close proximity thereto and at a predetermined rate;
- producing timing signals;
- generating character data signals in response to the timing signals;
- generating periodic, sequentially-timed command signals at a preselected repetition rate in response to the timing signals;
- and
- activating successive ones of the transducers selectively in response to command and character data signals to print characters on the printing medium as a matrix of rows and columns of dots, the interval between rows being determined by the spacing between transducers and the interval between columns being determined by the repetition rate of the command signals and the rate at which the printer head is driven.
Dependencies are inferred from the claim text.