Ergonomic head mounted display device and optical system

• US 9,753,286 B2
• Filed: 01/08/2016
• Issued: 09/05/2017
• Est. Priority Date: 12/24/2010
• Status: Active Grant

• Current Assignee: Magic Leap, Inc.
• Original Assignee: Magic Leap, Inc.
• Inventors: Gao, Chunyu, Hua, Hong, Lin, Yuxiang
• Primary Examiner(s): Stahl, Mike
• Application Number:
  US14/991,810
• Publication Number:
  US 20160154245A1
• Time in Patent Office: 606 Days
• Field of Search: None
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/013 comprising a combiner of particular shape, e.g. curvature
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/0176 characterised by mechanical features
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer

Abstract

This invention concerns an ergonomic optical see-through head mounted display device with an eyeglass appearance. The see-through head-mounted display device consists of a transparent, freeform waveguide prism for viewing a displayed virtual image, a see-through compensation lens for enabling proper viewing of a real-world scene when combined together with the prism, and a miniature image display unit for supplying display content. The freeform waveguide prism, containing multiple freeform refractive, and reflective surfaces, guides light originated from the miniature display unit toward a user'"'"'s pupil and enables a user to view a magnified image of the displayed content. A see-through compensation lens, containing multiple freeform refractive surfaces, enables proper viewing of the surrounding environment, through the combined waveguide and lens. The waveguide prism and the see-through compensation lens are properly designed to ergonomically fit human heads enabling a wraparound design of a lightweight, compact, and see-through display system.

Claims

1. An image display system which projects displayed virtual image into a pupil of a user through a waveguide prism, allowing the user to see displayed content overlaid upon a real world scene, where the system has a wide see-through field of view, of up to 90°

in the temple direction, up to 60°

in the nasal direction, and up to 60°

above and below a straight-ahead view, and where the system fits into the shape of an eyeglass form factor, the system comprising;

a. An image display unit 105, disposed towards the temple side of a users head, which projects light into a waveguide, where the image display unit is constrained to be outside of a reference curved surface defined by the shape of an average human head;

b. an optional coupling lens group 110, disposed between the image display unit and a waveguide, composed of one or more lenses, which guide light from the image display unit 105 into the waveguide 100 and corrects for optical aberration;

c. a transparent optical waveguide prism 100, which accepts the light from the image display unit and propagates the light until the, image is projected into the field of view of the user;

where the waveguide has. a physical inner surface 115, physical edge surface 120 and physical outer surface 125, a first refractive surface 130, and a second refractive surface 135, and a plurality of reflective surfaces, where the waveguide has a shape that fits into an eyeglass form factor and has a wide see-through field of view of up to 90°

in the temple direction, up to 60°

in the nasal direction, and up to 60°

above and below a straight-ahead view;

d. a compensation lens 160, secured to the physical outer surface 125 of the waveguide 100, which corrects for optical distortion caused by viewing the world through the waveguide prism;

where the inner surface of the compensation lens 165 approximates the shape of the outer surface 125 of the waveguide;

where a small air gap 195 is maintained between the compensation lens and the waveguide on surfaces where the total internal reflection criterion is satisfied for the outer surface 125 of the waveguide;

whereupon the image display unit 105 transmits light 140 into the optional coupling lens 110 followed by the waveguide 100, or into the waveguide directly, through a first refractive surface 130;

whereupon the light 140 follows a path 145 along the waveguide that comprises a plurality of reflections from the first refractive surface 130 to the second refractive surface 135;

whereupon light 140 passes through the second refractive surface 135 beyond which where the user places his or her pupil 150 to view the image;

whereupon light 198 from the real-world scene passes through the compensation lens 160 and the waveguide 100 before reaching the pupil 150, where the see-through field of view of the real-world scene is up to 90°

in the temple direction, up to 60°

in the nasal direction, and up to 60°

above and below a straight-ahead view.

2. The apparatus of claim 1, where the waveguide 100 and compensation lens 160 surfaces are jointly optimized for, a maximum see through field of view with a minimum of distortion, under the constraint that the total thickness of the waveguide 100 and compensation lens 160 be no more than a maximum thickness, and the size of the air gap 195 be no more than a maximum thickness, and the waveguide 100 have a width from the pupil to the temple greater than 25 mm.

3. The apparatus of claim 1, where the maximum thickness constraint of the joint waveguide and compensation lens is 40 mm and the maximum thickness of the air gap is 6 mm.

4. The apparatus of any one of claims 1-3 where an index matching glue is used, between the outer physical surface of the waveguide 125 and the inner surface 165 of the compensation lens, on portions of the waveguide outer surface 125 where the total internal reflection criterion is not used to produce a reflection, to cement the compensation lens 160 to the waveguide 100, and where an air gap 195 is otherwise maintained.

5. The apparatus of claim 1, where the image display unit 405 is disposed facing the waveguide first refractive surface 430, which lies on an edge surface of the waveguide, where there is a coupling lens 410 between the image display unit and the waveguide prism 400 which corrects for optical aberration and improves the image quality;

where the image display unit 405 emits ray bundles 440a 440b 440c which enter the waveguide through a First refractive surface 430, are reflected five times by the reflective surfaces before exiting through a second refractive surface 435, before reaching the user'"'"'s pupil 450.

6. The apparatus of claim 1, where the image display unit 505 is disposed facing the inner surface of the waveguide, where the image display unit emits three ray bundles 540a 540b 540c which enters the first inner refractive surface 530 of the waveguide, where the rays are reflected five times by the reflective surfaces (R1-5);

before reaching the exit pupil 550 where they comprise a virtual image, where there is a coupling lens 510 between the image display unit and the waveguide prism which corrects for optical aberration and improves the image quality.

7. The apparatus of claim 1, where there is a coupling lens 610 between the image display unit 605 and the waveguide prism 600 which corrects for optical aberration and improves the, image quality.

8. The apparatus of claim 1, where the image display unit 105 is based on a reflective-type illuminated pixel array selected from the group consisting of Liquid Crystal on Silicon (LCOS) microdisplay technology and Ferroelectric Liquid Crystal on Silicon (FLCoS), and where the image display unit 805 comprises:

a. A reflective-type illuminated pixel array micro-display panel 805a

b. A field lens 805b

c. A polarized beam splitter 805c

where the field lens 805b enforces telecentricity of light on the display surface,

where the beam splitter 806c acts as a beam combiner to merge the illumination light path.