Head-up display apparatus

A head-up display apparatus displaying a virtual image to be overlapped with scenery in front of a vehicle with respect to a driver by projecting a video image onto a windshield of the vehicle, the head-up display apparatus comprising:

• a vehicle information acquisition unit configured to acquire various kinds of vehicle information which can be detected by the vehicle;
• a controller configured to control display of the video image based on the vehicle information acquired by the vehicle information acquisition unit;
• a video image display configured to form the video image based on an instruction from the controller the vehicle information acquired by the vehicle information acquisition unit;
• a mirror configured to reflect the video image formed by the video image display to project onto the windshield;
• a mirror driver configured to change an angle of the mirror based on an instruction from the controller the vehicle information acquired by the vehicle information acquisition unit;
• and
• a display distance adjusting mechanism configured to adjust a display distance of the virtual image with respect to the driver and having an optical element disposed between the video image display and the mirror,
• wherein the optical element has a light control mirror capable of switching between transmitting and reflecting states, and
• wherein the controller adjusts the angle of the mirror via the mirror driver based on the vehicle information such that the virtual image can be displayed with respect to the driver to be overlapped with the scenery, and adjusts the display distance of the virtual image by controlling the transmitting and reflecting states of the light control mirror,
• acquires information relating to a first grade of a forward road as the vehicle information from the vehicle information acquisition unit, and information relating to a second grade of a road of a current place;
• adjusts, when the first grade is larger than the second grade by a predetermined threshold value or more, the angle of the mirror via the mirror driver such that a display position of the virtual image moves in an upward direction;
• and
• adjusts, when the second grade is larger than the first grade by a predetermined threshold value or more, the angle of the mirror via the mirror driver such that the display position of the virtual image moves in a downward direction, and
• wherein the controller adjusts the angle of the mirror via the mirror driver only when a state in which the first grade is larger than the second grade by the predetermined threshold value or more, or a state in which the second grade is larger than the first grade by the predetermined threshold value or more, continues for a predetermined period of time or more.