Projection type video display apparatus
US7997736B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 20, 2008 |
| Grant date | Aug 16, 2011 |
| Priority date | — |
| Expiry date | Oct 2, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B21/16
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projector comprises: a cooling fan for sucking ambient air through a filter; switching means for switching the operational mode of the cooling fan between a lowland mode and a highland mode; and control means adapted to obtain current fan voltage to determine the normal rpm value for that current fan voltage in reference to a highland voltage-rpm characteristic when the switching means is in the highland mode, obtain current fan rpm, and enables alarming means to issue a filter clogging alarm in the event that the current fan rpm is larger than the normal rpm value plus a predetermined value. Thus, filter clogging can be detected with precision in highlands.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.