Lightguide optical combiner for head wearable display

• US 9,915,823 B1
• Filed: 05/06/2014
• Issued: 03/13/2018
• Est. Priority Date: 05/06/2014
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Kress, Bernard C., Saeedi, Ehsan, Norton, Adam E., Schmidtlin, Edouard
• Primary Examiner(s): Pham, Thomas K
• Assistant Examiner(s): Pasko, Nicholas R
• Application Number:
  US14/271,083
• Time in Patent Office: 1,407 Days
• Field of Search: 359631
• CPC Class Codes: G02B 2027/0174 holographic
• 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 5/04 Prisms

Abstract

An eyepiece for a head wearable display includes a lightguide component for guiding display light and emitting the display light along at a viewing region. The light guide component includes an input surface oriented to receive the display light into the lightguide component at the peripheral location, a first folding surface disposed to reflect the display light received through the input surface, a second folding surface disposed to reflect the display light received from the first folding surface, an eye-ward facing surface disposed opposite to the second folding surface to reflect the display light received from the second folding surface, and a curved reflective surface having reflective optical power disposed at the viewing region to receive the display light reflected from the eye-ward facing surface and to reflect the display light for emission out through the eye-ward facing surface.

Claims

1. An eyepiece for a head wearable display, the eyepiece comprising:

a lightguide component for guiding display light received at a peripheral location offset from a viewing region and emitting the display light at the viewing region, the light guide component including;

an input surface oriented to receive the display light into the lightguide component at the peripheral location;

a first folding surface disposed to receive the display light from the input surface without reflection and to reflect the received display light;

a second folding surface disposed to face the first folding surface and to reflect the display light received from the first folding surface without an intervening reflection, wherein the input surface and the second folding surface are non-coplanar;

an eye-ward facing surface disposed to face the second folding surface and to reflect the display light received from the second folding surface, wherein the eye-ward facing surface is positioned as an emission surface for emitting the display light out of the lightguide component, wherein the first folding surface and the eye-ward facing surface are non-coplanar surfaces of the lightguide component that do not directly interface with each other by making contact, wherein the second folding surface and the eye-ward facing surface are non-coplanar, parallel surfaces that are both flat and both without optical power; and

a curved reflective surface having reflective optical power disposed at the viewing region to receive the display light reflected from the eye-ward facing surface and to reflect the display light for emission out through the eye-ward facing surface.

2. The eyepiece of claim 1, wherein the first folding surface, the second folding surface, and the eye-ward facing surface are clear surfaces that are oriented relative to each other to reflect the display light via total internal reflection.

3. The eyepiece of claim 1, wherein the input surface is a cylindrical surface that imparts optical power to the display light received into the lightguide component.

4. The eyepiece of claim 1, wherein the first folding surface is a cylindrical surface that imparts optical power to the display light reflected internally to the lightguide component.

5. The eyepiece of claim 1, wherein the curved reflective surface comprises a partially reflective surface that partially reflects the display light and transmits ambient scene light through the viewing region and operates to optically combine the ambient scene light with the display light.

6. The eyepiece of claim 5, further comprising:

a see-through add-on component mounted to the lightguide component along the curved reflective surface in the viewing region,

wherein the see-through add-on component is at least partially transparent to ambient scene light travelling along an eye-ward direction and is formed of a material having an index of refraction substantially equivalent to that of the lightguide component.

7. The eyepiece of claim 6, wherein the see-through add-on component includes:

an interface surface having a size and a curvature that mates to and complements the curved reflective surface of the lightguide component; and

an external scene facing surface that is complementary to the eye-ward facing surface in the viewing region such that the ambient scene light that passes through the see-through add-on component and the lightguide in the viewing region experiences substantially no optical power.

8. The eyepiece of claim 7, a diffusor coated onto end surfaces of the lightguide component and the see-through add-on component distal to the input surface to reduce back reflections down the lightguide component.

9. A head wearable display for displaying an image to a user, the head wearable display comprising:

a display source to generate display light;

a lightguide component for guiding display light received at a peripheral location offset from a viewing region and emitting the display light at the viewing region, the light guide component including;

an input surface to receive the display light into the lightguide component;

a first folding surface disposed to reflect the display light received through the input surface;

a second folding surface disposed to face the first folding surface and to reflect the display light received from the first folding surface without an intervening reflection, wherein the input surface and the second folding surface are non-coplanar;

an eye-ward facing surface disposed to face the second folding surface and to reflect the display light received from the second folding surface, wherein the eye-ward facing surface is positioned as an emission surface for emitting the display light out of the lightguide component, wherein the first folding surface and the eye-ward facing surface are non-coplanar surfaces of the lightguide component, wherein the second folding surface and the eye-ward facing surface are non-coplanar surfaces;

a curved reflective surface having reflective optical power disposed at the viewing region to receive the display light reflected from the eye-ward facing surface and to reflect the display light for emission out through the eye-ward facing surface;

a first notch surface that directly interfaces by contact with the input surface; and

a second notch surface that directly interfaces by contact with both the second folding surface and the first notch surface, wherein the first and second notch surfaces are non-coplanar with each other and non-coplanar with the input surface, the first folding surface, and the second folding surface;

wherein the first and second notch surfaces form an alcove in the lightguide component adjacent to the input surface;

a camera module disposed in the alcove, wherein a lens of the camera module faces outward from the lightguide component away from the eye-ward facing surface; and

a frame assembly to support the lightguide component and the display source for wearing on a head of the user with the viewing region positioned in front of the eye of the user.

10. The head wearable display of claim 9, wherein the first folding surface, the second folding surface, and the eye-ward facing surface are clear surfaces that are oriented relative to each other to reflect the display light via total internal reflection.

11. The head wearable display of claim 9, wherein the input surface and the first folding surface are cylindrical surfaces that impart optical power to the display light received into the lightguide component.

12. The head wearable display of claim 11, wherein the second folding surface and the eye-ward facing surface are planar surfaces with no optical power.

13. The head wearable display of claim 9, wherein the curved reflective surface comprises a partially reflective surface that partially reflects the display light and transmits ambient scene light through the viewing region and operates to optically combine the ambient scene light with the display light.

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

a see-through add-on component mounted to the lightguide component along the curved reflective surface in the viewing region,

wherein the see-through add-on component is at least partially transparent to ambient scene light and is formed of a material having an index of refraction substantially equivalent to that of the lightguide component.

15. The head wearable display of claim 14, wherein the see-through add-on component includes:

an interface surface having a size and a curvature that mates to and complements the curved reflective surface of the lightguide component; and

an external scene facing surface that is complementary to the eye-ward facing surface in the viewing region such that the ambient scene light that passes through the see-through add-on component and the lightguide in the viewing region experiences substantially no optical power.

16. An eyepiece for a head wearable display, the eyepiece comprising:

a lightguide component for guiding display light received at a peripheral location offset from a viewing region and emitting the display light at the viewing region, the light guide component including;

an input surface oriented to receive the display light into the lightguide component at the peripheral location;

a first folding surface disposed to receive the display light from the input surface without reflection and to reflect the received display light;

a second folding surface disposed to face the first folding surface and to reflect the display light received from the first folding surface without an intervening reflection, wherein the input surface and the second folding surface are non-coplanar;

an eye-ward facing surface disposed to face the second folding surface and to reflect the display light received from the second folding surface, wherein the eye-ward facing surface is positioned as an emission surface for emitting the display light out of the lightguide component, wherein the first folding surface and the eye-ward facing surface are non-coplanar surfaces of the lightguide component, wherein the second folding surface and the eye-ward facing surface are non-coplanar surfaces and wherein the first folding surface is a continuous surface that directly interfaces by contact to both the eye-ward facing surface and the input surface; and

a curved reflective surface having reflective optical power disposed at the viewing region to receive the display light reflected from the eye-ward facing surface and to reflect the display light for emission out through the eye-ward facing surface.