1. Field of the Invention
The present invention relates to a projection display apparatus for projecting an image on a projection plane.
2. Description of the Related Art
Recently, the development of projectors in which lasers with large radiation energy are used as light sources has been under way. It is necessary to take sufficient measures for a person not to erroneously enter a projection space through which the light that has been projected from such a projector pass.
Accordingly, a technique of detecting an entering person by a sensor, etc., has been proposed.
The aforementioned technique of detecting an entering person by using a sensor is effective when a screen is installed at a normal position and in a normal state. However, if a screen is not installed at a normal position or if a hole or a hollow is present in a screen, there is a possibility that the projected light may be guided to an unintended area.