Autofocus projection apparatus having focal-length fine adjustment, and projection light engines including the same
US11392020B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 2020 |
| Grant date | Jul 19, 2022 |
| Priority date | — |
| Expiry date | Nov 27, 2040 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B21/142
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An autofocus projection apparatus having focal-length fine adjustment is disclosed. A projection light engine including the same is also disclosed. The autofocus projection apparatus comprises a projection lens system, which comprises a first lens group, a second lens group, an aperture stop, a third lens group and a forth lens group arranged from a long conjugate side to a short conjugate side; a stepper motor, a control board, and a time-of-flight (TOF) distance measurement module; wherein the stepper motor is connected to an inner barrel for enclosing the second group lens through an adjustment level and only moves the second lens group for autofocus adjustment based on projection distances measured by the TOF distance measurement module. A 3D TOF module which includes a modulated flash light emitter and a CMOS camera sensor, can be used for automatic keystone correction as well as autofocus distance detection in the projection light engine.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.