HEAD UP DISPLAY WITH REDUCED PACKAGE DEPTH AND VOLUME

Abstract

A head up display arrangement for a motor vehicle includes an image source emitting a light field. A first freeform mirror is positioned to provide a first reflection of the light field. A generally concave second freeform mirror is positioned to receive the first reflection and provide a second reflection of the light field. The second reflection is reflected off of a windshield of the vehicle so as to be visible to a driver of the vehicle. An arcuate section of a surface of the generally concave second freeform mirror receives the first reflection and provides the second reflection. An angle between the first freeform mirror and an imaginary line that is tangent to a midpoint of the arcuate section of the surface of the generally concave second freeform mirror is approximately between thirty degrees and sixty degrees.

Claims

1. A head up display arrangement for a motor vehicle, the arrangement comprising: an image source configured to emit a light field; a first freeform mirror positioned to provide a first reflection of the light field; and a generally concave second freeform mirror positioned to receive the first reflection and provide a second reflection of the light field, the second reflection being reflected off of a windshield of the vehicle so as to be visible to a driver of the vehicle, an arcuate section of a surface of the generally concave second freeform mirror receiving the first reflection and providing the second reflection, an angle between the first freeform mirror and an imaginary line that is tangent to a midpoint of the arcuate section of the surface of the generally concave second freeform mirror being approximately between thirty degrees and sixty degrees.

2. The head up display arrangement of claim 1 wherein the angle is approximately between forty and fifty degrees.

3. The head up display arrangement of claim 2 wherein the angle is approximately forty-five degrees.

4. The head up display arrangement of claim 1 wherein the image source comprises a diffuser.

5. The head up display arrangement of claim 1 wherein the generally concave second freeform mirror includes a curvature substantially described by an extended polynomial description in a Zemax optical design software program.

6. The head up display arrangement of claim 1 wherein the second reflection is reflected off of the windshield of the vehicle so as to be visible to the driver as a virtual image disposed outside the windshield and visible through the windshield.

7. The head up display arrangement of claim 6 wherein the virtual image is approximately between six and eight meters from the driver.

8. The head up display arrangement of claim 6 wherein the virtual image measures 104 within a field of view of 11.44.3 as seen by the driver.

9. A head up display method for a motor vehicle, the method comprising: emitting a light field; providing a first freeform mirror positioned to provide a first reflection of the light field; and providing a generally concave second freeform mirror positioned to receive the first reflection and produce a second reflection of the light field, the second reflection being reflected off of a windshield of the vehicle so as to be visible to a driver of the vehicle, an arcuate section of a surface of the generally concave second freeform mirror receiving the first reflection and producing the second reflection, an angle between the first freeform mirror and an imaginary line that is tangent to a midpoint of the arcuate section of the surface of the generally concave second freeform mirror being approximately between thirty degrees and sixty degrees.

10. The method of claim 9 wherein the angle is approximately between forty and fifty degrees.

11. The method of claim 10 wherein the angle is approximately forty-five degrees.

12. The method of claim 9 wherein the light field is emitted by a diffuser.

13. The method of claim 9 wherein the generally concave second freeform mirror includes a curvature substantially described by an extended polynomial description in a Zemax optical design software program.

14. The method of claim 9 wherein the second reflection is reflected off of the windshield of the vehicle so as to be visible to the driver as a virtual image disposed outside the windshield and visible through the windshield.

15. The method of claim 14 wherein the virtual image is approximately between six and eight meters from the driver.

16. The method of claim 14 wherein the virtual image measures 104 within a field of view of 11.44.3 as seen by the driver.

17. A head up display arrangement for a motor vehicle, the arrangement comprising: an image source configured to emit a light field; a first freeform mirror positioned to provide a first reflection of the light field; a generally concave second freeform mirror having a reflective surface with an arcuate section, the arcuate section being positioned to receive the first reflection and provide a second reflection of the light field, an angle between the first freeform mirror and an imaginary line that is tangent to a midpoint of the arcuate section of the surface of the generally concave second freeform mirror being approximately between forty degrees and fifty degrees; and a windshield positioned to receive the second reflection and provide a third reflection of the light field, the third reflection being visible to a driver of the vehicle as a virtual image disposed outside of the windshield.

18. The head up display arrangement of claim 17 wherein the angle is approximately forty-five degrees.

19. The head up display arrangement of claim 17 wherein the generally concave second freeform mirror includes a curvature substantially described by an extended polynomial description in a Zemax optical design software program.

20. The head up display arrangement of claim 17 wherein the generally concave second freeform mirror includes a curvature substantially described by a Chebyshev polynomial description, a Zernike polynomial description, or a biconic Zernike description in a Zemax optical design software program.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings.

[0015] FIG. 1 is a schematic bottom view of one example embodiment of a HUD optical arrangement of the present invention.

[0016] FIG. 2 is a schematic diagram of one example embodiment of a HUD system including the HUD optical arrangement of FIG. 1.

[0017] FIG. 3 is another schematic view of the mirrors and windshield of the HUD system of FIG. 2.

[0018] FIG. 4 is a schematic perspective view of the HUD system of FIG. 2.

[0019] FIG. 5 is a flow chart of one embodiment of a head up display method of the present invention for a motor vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] FIG. 1 illustrates one embodiment of a HUD optical arrangement 10 of the present invention, including two reflective freeform mirrors 12 and 14. Mirror 14 is concave and is arranged to aim rays 16 to reflect from a windshield 18, as shown in FIG. 2, to be seen by a human driver 20. Rays 16 begin at diffuser 22, reflect from mirror 12, pass from mirror 14 to windshield 18, and reflect from windshield 18 to be seen by the driver. Mirror 12 is approximately flat and is oriented to reflect light rays or a light field from a display, or from an image presented on a diffuser 22, to mirror 14. To simplify FIG. 2, diffuser 22 and the ray from diffuser 22 to mirror 12 have been rotated about the ray from mirror 12 to mirror 14 so as to be in the same plane as the other objects shown in FIG. 2.

[0021] In one embodiment, diffuser 22 is a diffuser supplied by Kuraray Co., Ltd., of Tokyo, Japan. The image on the diffuser is created by a projector. The projector may be a DLP projector such as a digital imaging system including micromirrors separately controlled to create a digital image. In one embodiment, a digital light projector or a digital multi-mirror device in a kit marketed from Texas Instruments, may be used as the image source.

[0022] In one specific embodiment, arrangement 10 is applied to a head up display for augmented reality with a 11.44.30 field of view and a package volume of about 8.5 liters. The display may be in the form of a liquid crystal display having an 8040 mm active area.

[0023] Imaginary line 24 is tangent to a midpoint 26 of an arcuate section 28 of the surface of mirror 14 that receives the light field reflected off of mirror 12. An angle between mirror 12 and tangent line 24 may be approximately between 30 degrees and 60 degrees. In one embodiment, angle may be approximately between 40 degrees and 50 degrees. In another embodiment, angle may be approximately 45 degrees. Tangent line 24 may alternatively be thought of as an imaginary plane that is perpendicular to the page of FIG. 1.

[0024] The concave curvature of the surface of mirror 14 may be modeled and/or designed with an extended polynomial description in a Zemax optical design software program. Other aspherical mirror types within Zemax that could be used to model and/or design mirror 14 include a Chebyshev polynomial description, a Zernike polynomial description, and a biconic Zernike description. Another optical design software program that may be used to model and/or design mirror 14 is Code V.

[0025] FIG. 3 illustrates the mirrors and windshield of the HUD system of FIG. 2. FIG. 4 illustrates the HUD system of FIG. 2. Mirror A in FIGS. 3-4 corresponds to mirror 12 in FIGS. 1-2, and mirror B in FIGS. 3-4 corresponds to mirror 14 in FIGS. 1-2.

[0026] Each of mirrors 12 and 14 may be a freeform mirror. The term freeform may mean that the mirror is not flat, conical, or frusto-conical, wherein cylindrical is considered to be a special case of conical. Mirror 14 may be generally concave, but mirror 12 may be neither generally concave nor generally convex. Mirror 12 may be approximately flat, but is designed to direct the rays appropriately. The reflective surface of mirror 12 may be described in Zemax as an extended polynomial with twenty-seven terms, wherein the X and Y are two perpendicular axes, and the value of the polynomial is the value of a third axis Z that is perpendicular to both of axes X and Y. The first two terms (X1Y0 and X0Y1) are constrained to zero, so the polynomial has twenty-five non-zero terms. The polynomial includes all possible terms in X, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6, and Y, Y2, Y.sup.3, Y.sup.4, Y.sup.5, Y.sup.6.

[0027] In a particular embodiment, the equations for mirror 12 and mirror 14 are described in the table below:

TABLE-US-00001 Term Mirror 12 Mirror 14 X1Y0 0 0 X0Y1 0 0 X2Y0 3.758216827681000E+000 4.806211017163000E001 X1Y1 1.900693923567000E+000 9.257022901890000E002 X0Y1 4.409111247532000E+000 2.405827111339000E+000 X3Y0 5.162006391704000E+000 1.639612087429000E001 X2Y1 3.061562001959000E+000 5.730690852151000E001 X1Y2 2.703129586368000E+000 1.432248526776000E002 X0Y3 1.596962055934000E+001 2.497339025215000E001 X4Y0 4.071721011694000E+000 3.430056338954000E002 X3Y1 2.815160693536000E+000 1.160820515645000E001 X2Y2 4.792150469313000E+000 2.051634427595000E001 X1Y3 1.471810878826000E+001 3.298219769185000E001 X0Y4 1.990887321837000E+001 6.728363234852000E001 X5Y0 1.512055949803000E+000 3.326563715569000E002 X4Y1 9.012755498883001E001 3.903153809891000E002 X3Y2 4.234905523124000E+000 4.852380090258000E002 X2Y3 1.160242638340000E+001 1.987094538427000E001 X1Y4 1.578156095382000E+001 3.890998607212000E001 X0Y5 7.852204663376000E+000 4.018131700378000E001 X6Y0 2.134147672800000E001 1.276349826294000E002 X5Y1 1.073218449779000E001 4.083118180811000E002 X4Y2 9.179753579871000E001 9.180506284074999E003 X3Y3 2.865078393453000E+000 7.129285790582000E002 X2Y4 4.869942297781000E+000 9.702818820677001E002 X1Y5 3.573718398775000E001 1.072724576979000E001 X0Y6 9.147369578713001E+000 1.125279474755000E001

[0028] For this embodiment, Z, the sum of all the terms, is vertical distance in mm. The variables X and Y are the respective horizontal distances in the X and Y direction, each divided by 100 mm (normalized to 100 mm). Accordingly, X and Y are dimensionless.

[0029] FIG. 5 illustrates one embodiment of a head up display method 500 of the present invention for a motor vehicle. In a first step 502, a light field is emitted. For example, diffuser 22 may emit a light field, as shown in FIGS. 1=2.

[0030] Next, in step 504, a first freeform mirror positioned to provide a first reflection of the light field is provided. For example, reflective freeform mirror 12 may be positioned to provide a first reflection of the light field emitted by diffuser 22.

[0031] In a final step 506, a generally concave second freeform mirror positioned to receive the first reflection and produce a second reflection of the light field is provided. The second reflection is reflected off of a windshield of the vehicle so as to be visible to a driver of the vehicle. An arcuate section of a surface of the generally concave second freeform mirror receives the first reflection and produces the second reflection. An angle between the first freeform mirror and an imaginary line that is tangent to a midpoint of the arcuate section of the surface of the generally concave second freeform mirror is approximately between thirty degrees and sixty degrees. For example, a generally concave second freeform mirror 14 may be positioned to receive the first reflection and produce a second reflection of the light field such that the second reflection is reflected off of windshield 18 of a vehicle so as to be visible to a driver 20 of the vehicle. An arcuate section 28 of the surface of mirror 14 receives the light field reflected off of mirror 12 and produces the second reflection. An angle between first freeform mirror 12 and an imaginary line 24 that is tangent to a midpoint 26 of arcuate section 28 of the surface of generally concave second freeform mirror 14 is approximately between thirty degrees and sixty degrees. The foregoing description may refer to motor vehicle, automobile, automotive, or similar expressions. It is to be understood that these terms are not intended to limit the invention to any particular type of transportation vehicle. Rather, the invention may be applied to any type of transportation vehicle whether traveling by air, water, or ground, such as airplanes, boats, etc.

[0032] The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention.