Information display device

• US 10,670,864 B2
• Filed: 10/27/2015
• Issued: 06/02/2020
• Est. Priority Date: 10/27/2015
• Status: Active Grant

• Current Assignee: Hitachi Industry & Control Solutions, Ltd. (Hitachi, Ltd.), Maxell, Ltd.
• Original Assignee: Maxell, Ltd.
• Inventors: Hirata, Koji, Yatsu, Masahiko, Sugiyama, Toshinori, Kajikawa, Hiroyuki, Kaneko, Kazuomi
• Primary Examiner(s): Akanbi, Isiaka O
• Assistant Examiner(s): Owens, Danell L
• Application Number:
  US15/768,840
• Publication Number:
  US 20180341110A1
• Time in Patent Office: 1,680 Days
• CPC Class Codes: B60K 2360/23 using reflectors
• CPC Class Codes: B60K 2360/25 using filters
• 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 35/23 Head-up displays [HUD] optical aspects of head-up displays G02B27/01
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0145 creating an intermediate image
• CPC Class Codes: G02B 2027/0185 Displaying image at variable distance
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/0955 Lenses lenses per se G02B3/00
• CPC Class Codes: G02B 27/0983 being curved
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence

Abstract

Provided is a small-sized information display device displaying video image information as a virtual image by use of an eyepiece optical system including a concave mirror having desired reflection characteristics in a specific polarization direction, where a liquid crystal display panel is used as a video image light source. The information display device has a liquid crystal display panel as a flat display forming video image information disposed therein, and includes a virtual image optical system including a member to be projected for displaying virtual images in front of a vehicle by making a video image displayed on the liquid crystal display panel reflect on the member to be projected. The virtual image optical system includes a concave mirror, and a reflective film of the concave mirror has desired reflection characteristics in a specific polarization direction, so that virtual images having uniform brightness and chromaticity can be obtained.

Claims

1. An information display device displaying a virtual image on a windshield of a vehicle based on video image information, comprising:

a display element displaying the video image information; and

a virtual image optical system displaying the virtual image in front of the vehicle as viewed from a driver'"'"'s point of view by reflecting a video image light emitted from the display element on the windshield,

wherein the virtual image optical system includes;

a concave mirror disposed on an optical path of the video image light and between the display element and the windshield; and

a refractive optical element disposed on the optical path and between the display element and the concave mirror,

wherein the concave mirror includes a reflection surface made of a metal film, having a high and uniform spectral reflectance with respect to a visible light, on a front surface of a base material at a portion where the video image light having passed through the refractive optical element is reflected onto a region of the windshield,

wherein the refractive optical element has a shape that allows optical distance conversion and aberration correction to be performed for each virtual image of a plurality of virtual images and is disposed such that the each virtual image of the plurality of virtual images is established as the virtual image at a plurality of positions which include an upper position, a middle position and a lower position at separate line-of-sight directions and at separate distances from the viewpoint positions and which correspond to viewpoint positions of the driver from an upper portion to a lower portion of the windshield, and such that a video image light flux is separated to establish the each virtual image between the display element and the concave mirror,

wherein the lower position among the plurality of positions of the plurality of virtual images is a proximal position in front of the windshield and on a side closer to the windshield, and the upper position is a distal position on a side farther away from the windshield,

wherein the refractive optical element includes;

a first portion for establishing a first virtual image to be formed at the proximal position;

a second portion for establishing a second virtual image to be formed at the middle position; and

a third portion for establishing a third virtual image to be formed at the distal position,

wherein the virtual image optical system further includes a cylinder mirror disposed on the optical path and between the display element and the concave mirror, and

wherein the refractive optical element is a stepped filter disposed between the display element and the cylinder mirror and in proximity to a subsequent step of the display element.

2. The information display device according to claim 1,

wherein, in the virtual image optical system, a first lens having a positive refractive power and a second lens having a negative refractive power are independently disposed in this order in a direction from the display element to the concave mirror, on the optical path and between the display element and the concave mirror.

3. The information display device according to claim 1,

wherein the display element displays the video image information as a plurality of video image information on a plurality of divided regions or a plurality of display elements so as to correspond to the plurality of virtual images.

4. The information display device according to claim 1,

wherein the information display device detects a position of a viewpoint of the driver, and corrects an image of the video image information on the display element such that distortion of the virtual image is corrected in accordance with the detected position of the viewpoint.

5. The information display device according to claim 1,

wherein the concave mirror includes a reflective film made of silver or a silver alloy formed on a plastic substrate.

6. The information display device according to claim 1,

wherein the concave mirror includes an aluminum reflective film formed on a plastic substrate, and a reflection enhancing film formed on an interfacial surface of the reflective film on a side contacting air.

7. The information display device according to claim 1,

wherein the concave mirror includes a reflective film made of silver or a silver alloy formed on a glass substrate.

8. The information display device according to claim 1,

wherein the concave mirror includes an aluminum reflective film formed on a glass substrate, and a reflection enhancing film formed on an interfacial surface of the reflective film on a side contacting air.

9. The information display device according to claim 1,

wherein the cylinder mirror includes a reflective film made of silver or a silver alloy formed on a plastic substrate.

10. The information display device according to claim 1,

wherein the cylinder mirror includes a reflective film made of silver or a silver alloy formed on a glass substrate.

11. The information display device according to claim 1,

wherein the cylinder mirror includes an aluminum reflecctive film formed on a plastic substrate, and a reflection enhancing film formed on an interfacial surface of the reflective film on a side contacting air.

12. The information display device according to claim 1,

wherein the cylinder mirror includes an aluminum reflective film formed on a glass substrate, and a reflection enhancing film formed on an interfacial surface of the reflective film on a side contacting air.

13. The information display device according to claim 1,

wherein the display element includes a light source including a solid light source, an optical element reducing a divergence angle of diverging light from the solid light source, an optical member polarizing and converting the diverging light the divergence angle of which is reduced by the optical element, and an illumination light source section making light in a desired polarization direction incident on the display element.

14. The information display device according to claim 1,

wherein a λ

/4 plate is provided on a side of the virtual image optical system of the display element.

15. The information display device according to claim 1,

wherein an optical member reflecting an ultraviolet ray, an infrared ray, or both ultraviolet ray and infrared ray is provided on a side of the virtual image optical system of the display element.

16. The information display device according to claim 1,

wherein, in the refractive optical element, a first refractive optical element for the first virtual image is disposed in the first portion of the refractive optical element, a second refractive optical element for the second virtual image is disposed in the second portion, and no object is disposed in the third portion based on a design of the virtual image optical system optimized for the position of the third virtual image.

17. The information display device according to claim 1,

wherein the refractive optical element includes a common optical element having a shape such that an optical distance is continuously changed to continuously change positions of the virtual image in front of the windshield.

18. The information display device according to claim 1,

wherein the windshield has a curved surface satisfying a relation in which a curvature radius in a horizontal direction is larger than a curvature radius in a vertical direction,

wherein the cylinder mirror has a shape that is asymmetrical with respect to an optical axis for correcting distortion caused by a shape of the curved surface of the windshield.

19. The information display device according to claim 1,

wherein the concave mirror includes a free-form surface mirror having a shape that is rotationally asymmetrical with respect to an optical axis of the video image light for correcting distortion of the virtual image.

20. The information display device according to claim 1,

wherein the virtual image optical system includes a free-form surface lens disposed on the optical path and between the display element and the concave mirror and having a shape that is rotationally asymmetrical with respect to an optical axis of the video image light for correcting distortion of the virtual image.