Planetarium moon projector
US4020568A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 24, 1976 |
| Grant date | May 3, 1977 |
| Priority date | — |
| Expiry date | Mar 24, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09B27/02
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A planetarium moon projector of the direct casting type includes two alternatively interchangeable occulting elements which rotate at twice the period of moon phasing to intercept the projected light beam and effect the waxing and waning of the moon, and which are conically shaped with the same convergent angle as the projected convergent light and with an occulting relief angle. Two intermittent gears revolve integrally with the occulting elements and there is provided a fixed cylindrical rail with a rack, which keeps contact with the intermittent gears, and which interchanges the occulting elements when the intermittent gears are engaged with the rack. An eccentric drive coupling is provided to correct the dislocation of the moon phase caused by the occulting relief angle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.