Scanning apparatus for halftone image screen writing
US4965599A · kind A · utility
144Cited by
4References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1989 |
| Grant date | Oct 23, 1990 |
| Priority date | — |
| Expiry date | Nov 13, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4055
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Moire patterns in raster-scanned halftone dots image screens generated by multi-element line scanner devices are rendered imperceptible to the human eye by selecting the number of elements in the line scanner device to be that number which makes the "once-around" scanner frequency an integral multiple of the halftone dot screen frequency and makes the beat frequencies between the scanner and frequencies either fall outside the nominal visible spatial frequency range of about 2.5 to 250 lines per inch or fall on the screen frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.