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

An HUD includes: a projection display unit that spatially modulates light emitted from a light source on the basis of image information and projects image light obtained as a result of spatial modulation onto a windshield to display an image; a housing that accommodates the projection display unit and has an opening portion K through which the image light exits; an object removing mechanism that removes an object adhered to a front surface of a cover covering the opening portion by scraping the front surface of the cover; a region detecting unit that detects an object adhesion region in which the object is adhered to the cover; and an object removal control unit that activates the object removing mechanism in a case where important display content is included in a portion of the image light, the portion being blocked due to the object adhesion region.