Projection display apparatus and focus adjustment method for the same

A projection display apparatus comprising:

• a projection unit configured to project an image onto a screen;
• an image output unit configured to output a distance measurement image to the projection unit;
• a light-receiving unit configured to receive, by a plurality of light-receiving elements aligned along a direction crossing a projection optical axis of the projection unit, distance measurement image light which is projected on the screen by the projection unit and reflected by the screen, and output a signal corresponding to a position at which the distance measurement image light is received;
• a distance calculation unit configured to calculate a distance between the projection unit and the screen by a trigonometric distance measurement on the basis of the signal output from the light-receiving unit, and output a control signal based on the calculated distance;
• and
• a focus adjustment unit configured to adjust a focus of the projection unit on the basis of the control signal output by the distance calculation unit.