Display device and vehicle head-up display apparatus

A display device, comprising:

• a substrate, a light source device on the substrate, a transmission-type display panel, and an illumination optical system configured to guide illumination light from the light source device to the display panel;
• wherein
• the illumination optical system comprises:
• a first reflector at a different position on the substrate than the light source device;
• a quarter-wave plate between the first reflector and the display panel;
• a reflective polarizer between the quarter-wave plate and the display panel;
• and
• a lens configured to convert the illumination light into parallel light incident on the display panel perpendicularly;
• wherein
• the reflective polarizer has a convex shape, formed on a surface of the reflective polarizer facing the light source device, that has a peak at a position corresponding to the light source device.

A display device comprising:

• a substrate, a light source device on the substrate, a transmission-type display panel, an illumination optical system configured to guide illumination light from the light source device to the display panel, and a sidewall extending in a direction connecting the substrate and the display panel;
• wherein
• the display panel comprises an entrance-side polarizer that is a reflective polarizer;
• and
• the illumination optical system comprises:
• a first reflector at a different position on the substrate than the light source device;
• a quarter-wave plate between the first reflector and the display panel;
• and
• a second reflector on a surface of the sidewall facing a light path of the illumination light.

A display device, comprising:

• a substrate, a light source device on the substrate, a transmission-type display panel, and an illumination optical system configured to guide illumination light from the light source device to the display panel;
• wherein
• the illumination optical system comprises:
• a first reflector at a different position on the substrate than the light source device;
• a quarter-wave plate between the first reflector and the display panel;
• a reflective polarizer between the quarter-wave plate and the display panel;
• a lens configured to convert the illumination light into parallel light incident on the display panel perpendicularly;
• and
• a diffusing plate between the lens and the reflective polarizer;
• wherein
• the reflective polarizer has a convex shape, formed on a surface of the reflective polarizer facing the light source device, that has a peak at a position corresponding to the light source device.