Compact near-eye display optics

• US 10,095,036 B2
• Filed: 02/04/2016
• Issued: 10/09/2018
• Est. Priority Date: 02/04/2016
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Carollo, Jerome, Hu, Xinda, Bierhuizen, Serge
• Primary Examiner(s): EARLES, BRYAN E
• Application Number:
  US15/015,608
• Publication Number:
  US 20170227777A1
• Time in Patent Office: 978 Days
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0152 involving arrangement aiming to get lighter or better balanced devices
• 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 27/148 including stacked surfaces having at least one double-pass partially reflecting surface
• 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

Abstract

Systems and methods that employ a near-eye display system including an optical assembly are described. The optical assembly may include a head-mounted display device worn by a user in which the head-mounted display device adapted to house an image projecting device and an optical assembly. The optical assembly may include, for at least one eyepiece, a first flat filter stack operable to be oriented in a first direction. and a second flat filter stack operable to be oriented in a second direction. The near-eye display system assembly may also include a display panel adapted to receive image content from the image projecting device, wherein the display panel is adapted to be oriented in the second direction.

Claims

1. A near-eye display system assembly comprising:

a head-mounted display device including an image projecting device and an optical assembly, the optical assembly including for each of a first eyepiece and a second eyepiece,

at least one lens;

a first flat filter stack including at least one surface coated with a flat beam splitting layer;

a second flat filter stack stacked between the at least one lens and the first flat filter stack; and

a display panel adapted to receive image content from the image projecting device,

wherein each display panel is tilted from a non-zero tilt of a normal direction of the respective display panel to a first angle with an optical axis of the at least one lens, and each respective first flat filter stack is tilted from a non-zero tilt of a normal direction of each respective first flat filter stack to a second angle with the optical axis of the at least one lens, the first angle being different than the second angle.

2. The system of claim 1, wherein the first flat filter stack is adjacent to the second flat filter stack and configured into a stacked arrangement, wherein:

the first flat filter stack includes a first linear polarizer stacked between the display panel and a first quarter wave plate, the first quarter wave plate stacked between the first linear polarizer and a beam splitter; and

the second flat filter stack includes a polarizing beam splitter stacked between a second quarter wave plate and a second linear polarizer,

wherein the second linear polarizer is adjacent to the at least one lens.

3. The system of claim 1, wherein the display panel of each eyepiece is configured to be positioned adjacent to the focal point of the optical assembly to form a virtual image for display on the display panel of each respective eyepiece to modify a field of view of the near-eye display system.

4. The system of claim 1, wherein the at least one lens for each respective eyepiece is fixed and disposed in the head-mounted display device adjacent to the second flat filter stack and adapted to receive image content originating at the image projecting device and through the optical assembly toward the second flat filter stack of each respective eyepiece.

5. The system of claim 1, wherein the first angle is up to 12.5 degrees from a non-zero tilt of the normal direction of the respective display panel, and the second angle is up to 25 degrees from the non-zero tilt of the normal direction of the respective first flat filter stack,

wherein the tilt of the respective display panels provides increased spacing between at least one edge of each respective display panel for fitting the near-eye display system assembly to a user.

6. A method of filtering light for a near-eye display system, the method comprising:

receiving a light beam at a display panel and from a display that directs light through a first linear polarizer in a first filter stack, the first linear polarizer transmitting the light beam into a first quarter-wave plate in the first filter stack, the light beam becoming circularly polarized in a first direction and being further transmitted through a beam splitter in the first filter stack, the beam splitter operable to transmit at least some of the light beam to a second quarter wave plate in a second filter stack;

transmitting a first portion of the light beam from the second quarter wave plate to a polarizing beam splitter in the second filter stack to transform the first portion into a linearly polarized light beam, wherein the polarizing beam splitter is operable to reflect a second portion of the linearly polarized light beam through the second quarter wave plate to the beam splitter, the second portion becoming circularly polarized in a second direction after reflecting off of the beam splitter; and

transmitting the second portion from the beam splitter through the second quarter wave plate and through the polarizing beam splitter, through a second linear polarizer in the second filter stack, and through at least one lens to provide a refracted image to an eyepiece of the near-eye display system,

wherein the display panel and second filter stack are arranged in parallel and tilted from a normal to the optical axis of the at least one lens to adjust focus for the near-eye display system.

7. The method of claim 6, wherein the first portion of the light beam is orthogonal to a passing state of the polarizing beam splitter, and wherein the second portion of the light beam is parallel to the passing state of the polarizing beam splitter.

8. The method of claim 6, wherein the first direction includes right hand circularly polarized and the second direction includes left hand circularly polarized.

9. The method of claim 6, wherein at least some of the light beam from the display is passed into the first quarter wave plate from the first linear polarizer, wherein the first quarter wave plate is seated at about 45 degrees off of a vertical, the vertical corresponding to a longitudinal edge of the first filter stack.

10. The method of claim 6, wherein the first filter stack and the second filter stack are flat, non-curved elements.

11. The method of claim 6, wherein axes of the first linear polarizer and the second linear polarizer are orthogonal, and wherein axes of the first quarter wave plate and the second quarter wave plate are orthogonal.

12. The method of claim 6, wherein the first filter stack and second filter stack do not provide optical magnification.

13. The method of claim 6, wherein the beam splitter comprises a partial-mirror coating on the first filter stack and performs a beam splitting ratio of about 50 percent, and wherein about 25 percent of the second portion is transmitted from the beam splitter to the display if the display is linearly polarized, and about 12.5 percent of the second portion is transmitted from the beam splitter to the display if the display is unpolarized.

14. A system comprising:

an interactive head-mounted display device adapted to house an image projecting device and an optical assembly, the optical assembly including, for a first eyepiece and a second eyepiece,

at least one refracting lens;

a first flat filter stack including at least one surface coated with a flat beam splitting layer;

a second flat filter stack stacked between the at least one lens the first flat filter stack; and

a display panel adapted to receive image content from the image projecting device; and

at least one processor for handling image content for display on the image projecting device,

wherein each display panel is tilted from a non-zero tilt of a normal direction of the respective display panel to a first angle with an optical axis of the at least one lens, and each respective first flat filter stack is tilted from a non-zero tilt of a normal direction of each respective first flat filter stack to a second angle with the optical axis of the at least one lens, the first angle being different than the second angle.

15. The system of claim 14, wherein the beam splitting layer comprises a partial-mirror coating on the first filter stack, the beam splitting layer coating operable to split light with a splitting ratio of about 50 percent, and wherein about 25 percent of the light is transmitted from the beam splitting layer to the display if the display is linearly polarized, or about 12.5 percent of the light is transmitted from the beam splitting layer to the display if the display is unpolarized.

16. The system of claim 14, wherein the first filter stack is coupled to the second filter stack and configured into a stacked arrangement including:

the first filter stack having a first linear polarizer stacked between the display panel and a first quarter wave plate, the first quarter wave plate stacked between the first linear polarizer and a beam splitting layer;

the second filter stack having a polarizing beam splitter stacked between a second quarter wave plate and a second linear polarizer, and

wherein the second linear polarizer is adjacent to the at least one refracting lens.

17. The system of claim 14, wherein the first angle is up to about 12.5 degrees from a non-zero tilt of the normal direction of the respective display panel, and the second angle is up to about 25 degrees from the non-zero tilt of the normal direction of the respective filter stack,

wherein the tilt of the respective display panels provides increased spacing between the respective display panels for fitting the interactive head-mounted display device to a user.

18. The system of claim 14, wherein the image projecting device comprises a display on a mobile computing device, the display being an organic light emitting display (OLED).

19. The system of claim 14, wherein the image projecting device comprises a display on a mobile computing device, the display being a liquid crystal display (LCD) and wherein the second filter stack is configured without a linear polarizer.

20. The system of claim 14, wherein the image projecting device includes a display that is a reflective display that comprises a liquid crystal on silicon (LCOS) display.