Virtual image display device

A virtual image display device configured to display a virtual image for a vehicle comprising:

• a backlight that provides illumination light;
• and
• an image display panel that transmits the illumination light and displays an image to be imaged as the virtual image on a display screen, wherein
• the backlight has
• a light source unit that emits the illumination light toward the image display panel, and
• a deflection prism array arranged on an optical path between the light source unit and the image display panel, the deflection prism array including deflection prism elements arranged to deflect the illumination light from the light source unit while transmitting the illumination light,
• the deflection prism array deflects a direction of an after-transmission vector corresponding to a Poynting vector of the illumination light immediately after passing through the deflection prism array with respect to a direction of a before-transmission vector corresponding to a Poynting vector of the illumination light immediately before passing through the deflection prism array,
• an angle formed between a unit normal vector of the display screen and the after-transmission vector is larger than an angle formed between the unit normal vector of the display screen and the before-transmission vector,
• the light source unit has a light source arrangement surface,
• a direction of a vector difference obtained by subtracting the before-transmission vector from the after-transmission vector is defined as a deflection difference direction, and
• the image display panel is inclined so as to separate from the light source arrangement surface as extending from a closest portion of the image display panel the closest to the light source arrangement surface in the deflection difference direction.

A virtual image display device configured to display a virtual image for a vehicle comprising:

• a backlight that provides illumination light;
• and
• an image display panel that transmits the illumination light and displays an image to be imaged as the virtual image on a display screen, wherein the backlight has
• a light source unit that emits the illumination light toward the image display panel, and
• a deflection prism array arranged on an optical path between the light source unit and the image display panel, the deflection prism array including deflection prism elements arranged to deflect the illumination light from the light source unit while transmitting the illumination light,
• the deflection prism array deflects a direction of an after-transmission vector corresponding to a Poynting vector of the illumination light immediately after passing through the deflection prism array with respect to a direction of a before-transmission vector corresponding to a Poynting vector of the illumination light immediately before passing through the deflection prism array,
• an angle formed between a unit normal vector of the display screen and the after-transmission vector is larger than an angle formed between the unit normal vector of the display screen and the before-transmission vector,
• each of the deflection prism elements is formed in a triangular prism shape,
• the virtual image display device further comprising:
• an optical mixing prism array different from the deflection prism array and arranged on the optical path between the light source unit and the image display panel, wherein
• the optical mixing prism array includes optical mixing prism elements arranged to deflect the illumination light from the light source unit while transmitting the illumination light,
• the optical mixing prism elements locally deflect illumination lights in directions different from each other,
• the optical mixing prism array mixes the illumination lights transmitting through the optical mixing prism elements different from each other while maintaining a direction of a vector sum of Poynting vectors of the illumination light between before and after passing through the optical mixing prism array, and
• the deflection prism array and the optical mixing prism array are integrally formed with each other to form a prism array member.