PROJECTION DISPLAY DEVICE, AND OPERATION METHOD AND OPERATION PROGRAM FOR PROJECTION DISPLAY DEVICE

An HUD includes a housing that accommodates a light modulation unit that spatially modulates light emitted by a light source; a projection optical system that is accommodated in the housing and projects the light that has been spatially modulated onto a windshield through an opening portion K of the housing; a cover that closes the opening portion K; a separation member that is movable and is for separating a front surface of the cover into a plurality of regions; a driving unit; and an object detecting unit that detects an object approaching the front surface of the cover. The driving unit moves the separation member to a position on the cover to separate the cover into a plurality of regions when the object detecting unit detects an object, and leaves the separation member retracted from the position on the cover when an object is not detected.