Head-up display device

A head-up display device mounted on a moving object for projecting an image onto a projection member to display the image as a virtual image visually recognizable by an occupant, the head-up display device comprising:

• a projection unit configured to project a display light of the image as a linear polarized light;
• and
• a light guide unit configured to provide an optical path through which to guide the display light to the projection member, wherein the light guide unit includes:
• a first phase shifter that is disposed on the optical path to convert the display light as the linear polarized light from the projection unit into a circularly polarized light and that includes a reflection surface, which is provided to be directed to the projection member and to be capable of reflecting a light from the projection member side to the projection member side;
• a second phase shifter that is disposed on the projection member side of the first phase shifter on the optical path and is configured to give a phase difference of a ¼ wavelength to the display light converted into the circularly polarized light by the first phase shifter to convert the display light into a linear polarized light;
• and
• a linear polarizer that is disposed on the projection member side of the second phase shifter on the optical path to guide a light whose polarization direction is along a light guide axis and to shield a light whose polarization direction is along a light shield axis perpendicular to the light guide axis, wherein the linear polarizer is provided to arrange the light guide axis along a polarization direction of the display light converted into the linear polarized light by the second phase shifter to guide the display light toward the projection member, wherein:
• the light guide unit further includes a multilayer film reflecting mirror configured to guide the display light by its reflection on an optical multilayer film on the optical path;
• and
• the second phase shifter is a ¼ wavelength plate provided to be capable of transmitting the display light and is disposed between the first phase shifter and the multilayer film reflecting mirror.

A head-up display device mounted on a moving object for projecting an image onto a projection member to display the image as a virtual image visually recognizable by an occupant, the head-up display device comprising:

• a light source configured to project a display light of the image as a linear polarized light;
• and
• a light guide unit configured to provide an optical path through which to guide the display light to the projection member, wherein the light guide unit includes:
• a ¼ wavelength plate that is disposed on the optical path to convert the display light as the linear polarized light from the light source into a circularly polarized light and that includes a reflection surface, which is provided to be directed to the projection member and to be capable of reflecting a light from the projection member side to the projection member side;
• a ⅛ wavelength plate that is disposed on the projection member side of the ¼ wavelength plate on the optical path and is configured to give a phase difference of a ¼ wavelength to the display light converted into the circularly polarized light by the ¼ wavelength plate to convert the display light into a linear polarized light;
• and
• a linear polarizer that is disposed on the projection member side of the ⅛ wavelength plate on the optical path to guide a light whose polarization direction is along a light guide axis and to shield a light whose polarization direction is along a light shield axis perpendicular to the light guide axis, wherein the linear polarizer is provided to arrange the light guide axis along a polarization direction of the display light converted into the linear polarized light by the ⅛ wavelength plate to guide the display light toward the projection member.