Head-up display device

• US 9,829,704 B2
• Filed: 07/14/2015
• Issued: 11/28/2017
• Est. Priority Date: 07/30/2014
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Nambara, Takahiro
• Primary Examiner(s): Dowling, William C
• Application Number:
  US15/326,982
• Publication Number:
  US 20170199382A1
• Time in Patent Office: 868 Days
• Field of Search: 353 12- 14, 359629-633
• CPC Class Codes: B60K 2360/27 using semi-transparent optical elements
• CPC Class Codes: B60K 2360/334 Projection means
• CPC Class Codes: B60K 35/00 Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
• CPC Class Codes: B60K 35/213 Virtual instruments
• CPC Class Codes: B60K 35/81 for controlling displays
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/013 comprising a combiner of particular shape, e.g. curvature
• CPC Class Codes: G02B 2027/0159 with mechanical means other than scaning means for positioning the whole image
• CPC Class Codes: G02B 2027/0185 Displaying image at variable distance
• CPC Class Codes: G02B 26/0825 the reflecting element being a flexible sheet or membrane, e.g. for varying the focus flexible mirrors for cosmetic use A45D42/24
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/0149 characterised by mechanical features G02B27/0176 takes precedence
• CPC Class Codes: G02B 27/0179 Display position adjusting means not related to the information to be displayed
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 21/008 using micromirror devices
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 21/62 Translucent screens

Abstract

An HUD device which is installed on a vehicle and displays an image as a virtual image in a visible region in a manner that is visually recognizable to an occupant by projecting the image onto a windshield includes an oscillator which oscillates a laser light flux, a screen member which has unevenness in a projection region in which the image is formed by projection of the laser light flux, a projection optical system which projects the laser light flux onto the screen member, a magnifying optical system which magnifies the image, projects the image onto the windshield, and guides light of the image to the visible region, and a controller which causes a focal length of the projection optical system to temporally oscillate. Accordingly, an appropriate visible region is secured, luminance inconsistencies in an image which is visually recognized are suppressed, and it becomes easy to secure space.

Claims

1. A head-up display device, mounted on a moving object, that displays an image as a virtual image in a visible region in a manner that is visually recognizable to an occupant by projecting the image onto a projection member, comprising:

an oscillator which oscillates laser light flux;

a screen member which has unevenness in a projection region in which the image is formed by projection of the laser light flux;

a projection optical system which projects the laser light flux onto the screen member;

a magnifying optical system which magnifies the image, projects the image onto the projection member, and guides light of the image to the visible region; and

a variable focal point unit which causes a focal length of the projection optical system to temporally oscillate.

2. The head-up display device according to claim 1,

wherein the projection optical system includes a scanning unit which temporally scans a projection direction of the laser light flux, and

wherein an oscillation period in which the variable focal point unit causes the focal length to periodically oscillate is shifted from a frame rate of scanning of the scanning unit.

3. The head-up display device according to claim 2,

wherein the scanning unit is a scanning mirror of a micro electro mechanical system in which an orientation of a reflecting surface which reflects the laser light flux changes, and

wherein the variable focal point unit causes a radius of curvature of the reflecting surface to temporally fluctuate.

4. The head-up display device according to claim 3,

wherein the scanning mirror forms a transmission portion which transmits the laser light flux in a periphery of the reflecting surface.

5. The head-up display device according to claim 1,

wherein the screen member includes a plurality of optical elements which are arranged in a grid in the projection region and which have unevenness, and

wherein each of the optical elements forms a mirror surface shaped curved surface, which has a common curvature mode of convex surface curves and concave surface curves, on a surface of the screen member, and each of the optical elements causes the laser light flux to diffuse through the curved surface.

6. The head-up display device according to claim 5,

wherein a height at a surface vertex of the curved surface differs between adjacent ones of the optical elements.

7. The head-up display device according to claim 1,

wherein the screen member includes a diffusion surface which has unevenness in the projection region due to surface texturing, and diffuses the laser light flux through the diffusion surface.

8. The head-up display device according to claim 1,

wherein when a numerical aperture of the oscillator and the projection optical system is defined as NA, a wavelength of the laser light flux is defined as λ

, and a size on the screen member which corresponds to a visually recognizable limit of a spot radius δ

on the screen member of the laser light flux is defined as Δ

, Equation 1 which is denoted below is satisfied

9. The head-up display device according to claim 8,

wherein the numerical aperture is less than or equal to 0.018.

10. The head-up display device according to claim 1,

wherein when a numerical aperture of the oscillator and the projection optical system is defined as NA, a wavelength of the laser light flux is defined as λ

, a size on the screen member at which a spot radius δ

may not be visually recognized by sight when the laser light flux is projected onto the screen member is defined as Δ

, and a defocusing amount dS of the laser light flux in relation to the screen member is defined as dS, Equation 2 which is denoted below is satisfied

11. The head-up display device according to claim 10,

wherein an absolute value of the defocusing amount is less than or equal to 2237 μ

m.

12. The head-up display device according to claim 1,

wherein the variable focal point unit uses a variable focal point lens in which a lens focal length varies.