Lamp changing system for projectors
US4142129A · kind A · utility
4Cited by
5References
8Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | May 25, 1977 |
| Grant date | Feb 27, 1979 |
| Priority date | — |
| Expiry date | May 25, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B39/10
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A photocell illuminated by the projection lamp of a slide projector controls a spring-biased longitudinally movable lamp exchange carrier. Lamp failure causes a change of state in the photocell that electronically releases an electromagnetic lock and allows the spring-tensioned lamp carrier to change positions. The last spare lamp is screened from the photocell, causing the electronic circuit to energize a fluorescent diode to indicate that the last spare lamp is being used.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.