Printing grey scale images
US5142337A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 9, 1990 |
| Grant date | Aug 25, 1992 |
| Priority date | — |
| Expiry date | Oct 9, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G13/22
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electrophotographic printing process enables a two-color printer having only binary printing capability to produce high-quality monochrome grey-scale output having, for example, up to 100 grey levels in a 3.times.3 super-pixel through the use of a second toner comprising a mixture of opaque black, opaque white, and clear toner. A layer of the second toner is applied so as to overlie the first toner layer on the substrate, the first toner comprising black toner. The composition of the second toner may be, for example, 9 percent opaque black toner, 9 percent opaque white toner, and 82 percent clear toner. Another embodiment extends this concept to the high-quality, enhanced grey-scale printing of a color other than black. In another embodiment, the layer of the second toner is comprised of a mixture of equal amounts of opaque black toner and opaque white toner and is applied so as to overlie the first toner layer on the substrate, the first toner layer comprised of black toner having a charge-to-mass ratio in the range of 2 to 10 times less than the second toner. This embodiment is also extended to high-quality, enhanced grey-scale printing of a color other than black. The use of …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.