Lighthouse having a main filter and a supplemental filter
US4021820A · kind A · utility
2Cited by
5References
1Claims
0Family size
Assignees
Inventors
Key dates
| Filing date | Oct 23, 1975 |
| Grant date | May 3, 1977 |
| Priority date | — |
| Expiry date | Oct 23, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J9/2273
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An exposure lighthouse for use in printing screen structures for cathode-ray tubes comprising a lens assembly including a diffracting optical element, a main intensity-correction filter and a supplemental intensity-correction filter in series with the main filter. Both of the filters comprise preformed carbon particles in a light - transmitting binder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.