Head up display for vehicle

1. A head up display for a vehicle, comprising:

an imaging device configured to emit first linearly polarized light in a first direction and second linearly polarized light in a second direction perpendicular to the first direction;

a polarizing reflection mirror through which the first linearly polarized light is transmitted and from which the second linearly polarized light is reflected;

a second reflection mirror spaced apart from the polarizing reflection mirror and at which the first linearly polarized light transmitted through the polarizing reflection mirror is reflected to the polarizing reflection mirror; and

a first reflection mirror spaced from the polarizing reflection mirror and configured to reflect the second linearly polarized light reflected from the polarizing reflection mirror to a windshield of the vehicle to produce a first image having a first length from the windshield, and to reflect the first linearly polarized light reflected from the second reflection mirror and transmitted through the polarizing reflection mirror to the windshield of the vehicle to produce a second image having a second length from the windshield different than the first length.

2. The head up display of claim 1 , wherein the imaging device comprises:

an image source configured to emit the first linearly polarized light in the first direction; and

a half wavelength phase delay unit configured to convert a wavelength of a portion of the first linearly polarized light from the image source into the second linearly polarized light by a half of a wavelength.

3. The head up display of claim 2 , wherein the image source comprises:

a display panel configured to emit image light; and

a linear polarizer configured to linearly polarize the image light emitted from the display panel in the first direction, and

wherein the half wavelength phase delay unit faces a portion area of the linear polarizer.

4. The head up display of claim 2 , wherein the half wavelength phase delay unit is between a light emitting surface of the image source and a surface of the polarizing reflection mirror.

5. The head up display of claim 2 , wherein the polarizing reflection mirror faces the half wavelength phase delay unit and the image source in a vertical direction and faces the first reflection mirror in a longitudinal direction.

6. The head up display of claim 1 , wherein the imaging device comprises:

a display panel configured to emit image light;

a first linear polarizer configured to linearly polarize the image light emitted from the display panel in the first direction to produce the first linearly polarized light; and

a second linear polarizer configured to linearly polarize the image light emitted from the display panel in the second direction to produce the second linearly polarized light.

7. The head up display of claim 6 , wherein the first linear polarizer and the second linear polarizer face different areas from each other of the display panel.

8. The head up display of claim 6 , wherein the polarizing reflection mirror faces the first linear polarizer and the second linear polarizer in a vertical direction and faces the first reflection mirror in a longitudinal direction.

9. The head up display of claim 1 , wherein the polarizing reflection mirror includes an anti-reflection coating layer on a surface facing the second reflection mirror.

10. The head up display of claim 1 , wherein the polarizing reflection mirror is a wire grid polarizer disposed on a rear side of the first reflection mirror, and

wherein the second reflection mirror includes a flat mirror facing the wire grid polarizer.

11. The head up display of claim 1 , wherein front surfaces of the polarizing reflection mirror and the second reflection mirror are inclined toward a front lower side of the head up display.

12. The head up display of claim 1 , wherein the polarizing reflection mirror is inclined between the first reflection mirror and the second reflection mirror.

13. The head up display of claim 1 , further comprising:

a quarter wavelength phase delay unit between the polarizing reflection mirror and the second reflection mirror.

14. The head up display of claim 13 , further comprising:

a third reflection mirror facing the polarizing reflection mirror in a portion of a front surface of the quarter wavelength phase delay unit.

15. The head up display of claim 2 , wherein the half wavelength phase delay unit faces a portion of an emitting surface of the image source, and

wherein the head up display further comprises a prism at which the first linear polarizing light emitted from the image source toward a portion other than the half wavelength phase delay unit is refracted between the image source and the polarizing reflection mirror.

16. The head up display of claim 1 , further comprising:

at least one rotating device configured to rotate at least one of the polarizing reflection mirror and the second reflection mirror.

17. The head up display of claim 2 , wherein the imaging device further includes a separation barrier configured to prevent mutual interference of linearly polarized light in the first direction and linearly polarized light in the second direction.

18. The head up display of claim 17 , wherein the separation barrier includes:

a first barrier which is diagonally disposed on a light emitting surface of the image source; and

a second barrier which is disposed away from the first barrier and the light emitting surface of the image source.

19. The head up display of claim 18 , further comprising:

a space which is opened to face between the first reflection mirror and the polarizing reflection mirror between the first barrier and the second barrier.

20. The head up display of claim 18 , wherein the first barrier includes a protrusion portion which protrudes toward the half wavelength phase delay unit, and

wherein the protrusion portion is formed on an end portion away from the image source of both end portions of the first barrier wall.