Projection type display device and projection display method

A projection type display device comprising:

• a first light source that emits visible light;
• a projection receiving member which is disposed on a windshield of a vehicle, to which an image based on the visible light is projected;
• a second light source that emits ultraviolet light which decreases a light transmittance of the projection receiving member by irradiation of the projection receiving member;
• a projection unit that projects the visible light emitted from the first light source and the ultraviolet light emitted from the second light source to the projection receiving member;
• an imaging unit that performs imaging of a scene at front of the windshield of the vehicle;
• and
• a detection unit that detects an object image having brightness greater than or equal to a first threshold from a part, of captured image data of the scene acquired by imaging by the imaging unit, corresponding to a range where the projection receiving member is disposed,
• wherein the projection unit projects the ultraviolet light to at least a part of a region of the projection receiving member that corresponds to the object image detected by the detection unit.