Head-up display and moving body with head-up display mounted thereon
View Patent ↗A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form the image as an intermediate image, and includes a first optical element configured to condense light, a first lens configured to condense light, and a second optical element configured to diffuse light. The first optical element, the first lens, and the second optical element are disposed in this order along an optical path from the display device.
1. A head-up display configured to project a projection image formed from an original image on a transparent reflection member to cause an observer to visually recognize a virtual image, the head-up display comprising:
a device configured to emit beams for forming the projection image from the original image; and
a projection optical system configured to form the projection image from the original image and project the projection image as the virtual image for the observer, wherein:
the projection optical system is configured to form an intermediate image from the original image by the beams emitted from the device and form the projection image from the intermediate image,
the projection optical system includes:
a first mirror configured to reflect the beams emitted from the device;
a first lens configured to condense the beams reflected by the first mirror;
a second mirror configured to reflect the beams and form the intermediate image; and
a third mirror configured to reflect the beams that formed the intermediate image to the transparent reflection member as the projection image,
the first mirror, the first lens, the second mirror, and the third mirror are disposed in this order along an optical path to the transparent reflection member,
the optical path between the second mirror and the third mirror is a space, and
the intermediate image is an aerial image formed in the space on the optical path between the second mirror and the third mirror.
2. The head-up display according to claim 1 , wherein the intermediate image is formed at a position nearer to the second mirror than to the third mirror.
3. The head-up display according to claim 1 , wherein the third mirror is a concave mirror.
4. The head-up display according to claim 3 , wherein the third mirror has a free-form surface.
5. The head-up display according to claim 4 , wherein the second mirror has a free-form surface.
6. The head-up display according to claim 1 , wherein the projection optical system further includes a second lens disposed between the device and the first mirror, the second lens being configured to condense the beams emitted from the device.
7. The head-up display according to claim 1 , wherein the first mirror is configured to change a direction of a reference beam reflected toward the first lens with respect to the reference beam incident on the first mirror, the reference beam reaching a center of a viewpoint region of the observer and corresponding to a center of the virtual image.
8. The head-up display according to claim 7 , wherein the optical path between the first mirror and the first lens is a space, and the beams reflected by the first mirror is directly incident on the first lens.
9. The head-up display according to claim 7 , wherein the second mirror is configured to change a direction of the reference beam reflected toward the third mirror with respect to a direction of the reference beam reflected by the first mirror.