High speed thermal printing apparatus
US4990930A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 1990 |
| Grant date | Feb 5, 1991 |
| Priority date | — |
| Expiry date | Jun 4, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/17
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A continuous-tone thermal printer includes a transport mechanism for advancing a print medium past a thermal print head while continuous-tone image information is being printed, line-by-line, on the medium. To increase the rate at which thermal prints are produced, the printer includes asynchronous motor-control apparatus for selectively accelerating the movement of the print medium relative to the print head to quickly locate the print head at the start of a new image line immediately following the printing of that pixel(s) having the highest image density in the preceding image line. Preferably, such motor-control apparatus includes a digital signal processor which determines the maximum pixel density on each line. Upon printing such maximum pixel density, the digital signal processor causes a motor controller to temporarily increase the print medium velocity past the thermal print head to the start of the next image line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.