Methods of gradation control and picture quality improvement in a thermal printer which adapts a staggered printing system
US5721578A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1994 |
| Grant date | Feb 24, 1998 |
| Priority date | — |
| Expiry date | Dec 27, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4055
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A gradation control method in a color thermal transfer printer is adapted to express one pixel by a dot matrix with two rows and two coles, control a density value of one dot with a time for energizing a heating element of a thermal head, and carry out mask patterning for plotting only one of four dots when the gradation of each color for one pixel is not more than a prescribed value while plotting only two of the four dots when the gradation is in excess of the prescribed value. At this time, employed is a mask pattern of necessarily plotting cyan and magenta on dots which are different from each other. A picture quality improving method in a staggered printing system is adapted to plot a noted dot when at least one of such conditions that density data of the noted dot is in excess of a prescribed density value and that density data of any of four dots most approximate to the noted dot is not more than a prescribed low density value is satisfied, even if the noted dot corresponds to that to be masked.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.