Flexible light combiner backlight used in a head mounted display

• US 10,107,950 B2
• Filed: 12/06/2016
• Issued: 10/23/2018
• Est. Priority Date: 12/06/2016
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Facebook Technologies, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Tseng, Shie Ping Jeffrey, Richards, Evan M., Shi, Jianru, Shi, Yue
• Primary Examiner(s): Vu, Phu
• Application Number:
  US15/370,664
• Publication Number:
  US 20180156960A1
• Time in Patent Office: 686 Days
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G06F 1/163 Wearable computers, e.g. on a belt

Abstract

A liquid crystal display (LCD) device including a backlight with an LED assembly. The LED assembly includes a flexible light combiner and two or more different color LEDs optically coupled with a first end of the flexible light combiner. The flexible light combiner includes light channels that transmit color light, and output the color light at a second end of the flexible light combiner. The second end defines a light output region of the flexible light combiner. The light output regions of multiple LED assemblies are arranged behind an LCD panel, along one or more edges, to illuminate the LCD panel. The LED assembly provides edge-lit backlighting with enhanced brightness and color gamut, and flexible LED placement within the LCD device.

Claims

1. A liquid crystal display (LCD) device, comprising:

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit first light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light, respectively, in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the first color LED includes a first emission response time and the second color LED includes a second emission response time different from the first emission response time; and

the display device further includes a controller configured to adjust for the first emission response time being different from the second emission response time based on providing a first control signal to drive the first color LED and a second control signal to drive the second color LED, the first control signal including a timing offset relative to the second control signal.

2. The LCD device of claim 1, wherein the flexible light combiner includes a flexible cladding surrounding the flexible core.

3. The LCD device of claim 1, further comprising a plurality of LED assemblies, each of the LED assemblies including a light output terminal disposed behind the LCD panel along one or more edges of the LCD panel.

4. The LCD device of claim 1, wherein the first light channel includes a fiber optic cable.

5. The LCD device of claim 4, wherein the fiber optic cable is tapered such that the first end of the first light channel is thicker than the second end of the first light channel.

6. The LCD device of claim 1, wherein the first light channel homogenizes the first light and the second light channel homogenizes the second light.

7. The LCD device of claim 1, wherein:

the LED assembly includes a third color LED emitting third light at a third wavelength;

the flexible core of the flexible light combiner includes a third light channel to transmit the third light from the third color LED, a first end of the third light channel optically coupled with the third color LED;

the light output terminal is defined by a second end of the third light channel to output the third light in the first direction; and

the light guide is configured to combine the third light with the first light and the second light received from the light output terminal into the combined light to illuminate the LCD panel.

8. The LCD device of claim 7, wherein the first color LED is a red LED, the second color LED is a green LED, and the third color LED is a blue LED.

12. The display device of claim 1, wherein the first and second color LEDs are disposed away from the light guide.

9. A liquid crystal display (LCD) device, comprising:

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit first light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light, respectively, in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the backlight further includes a second LED assembly including a second flexible light combiner; and

at least one of the first or second color LED is connected with the a light channel of the second LED assembly.

10. A liquid crystal display (LCD) device, comprising:

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit first light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light, respectively, in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the light guide is disposed behind the LCD panel;

the LCD device further includes an eye cup disposed in front of the LCD panel; and

at least a portion of the flexible light combiner is wrapped around the eye cup such that the first and second LEDs are disposed along a surface of the eye cup.

11. A liquid crystal display (LCD) device, comprising:

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit first light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light, respectively, in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the first color LED has a lower efficiency than the second color LED; and

the display device further includes a controller configured to adjust for the first color LED having the lower efficiency than the second color LED based on providing a first control signal to drive the first color LED and a second control signal to the drive the second color LED, the first control signal including a higher current than the second control signal.

13. A head-mounted display (HMD), comprising:

a liquid crystal display (LCD) device, including;

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit red light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the first color LED includes a first emission response time and the second color LED includes a second emission response time different from the first emission response time; and

the display device further includes a controller configured to adjust for the first emission response time being different from the second emission response time based on providing a first control signal to drive the first color LED and a second control signal to drive the second color LED, the first control signal including a timing offset relative to the second control signal.

14. The HMD of claim 13, wherein the flexible light combiner includes a flexible cladding surrounding the flexible core.

15. The HMD of claim 13, further comprising a plurality of LED assemblies, each of the LED assemblies including a light output terminal disposed behind the LCD panel along one or more edges of the LCD panel.

16. The HMD of claim 13, wherein the first light channel includes a fiber optic cable.

17. The HMD of claim 16, wherein the fiber optic cable is tapered such that the first end of the first light channel is thicker than the second end of the first light channel.

18. The HMD of claim 13, wherein the first light channel homogenizes the first light and the second light channel homogenizes the second light.

19. The HMD of claim 13, wherein:

the LED assembly includes a third color LED emitting third light at a third wavelength;

the flexible core of the flexible light combiner includes a third light channel to transmit the third light from the third color LED, a first end of the third light channel optically coupled with the third color LED;

the light output terminal is defined by a second end of the third light channel to output the third light in the first direction; and

the light guide is configured to combine the third light with the first light and the second light received from the light output terminal into the combined light to illuminate the LCD panel.

20. The HMD of claim 19, wherein the first color LED is a red LED, the second color LED is a green LED, and the third color LED is a blue LED.

21. A head-mounted display (HMD), comprising:

a liquid crystal display (LCD) device, including;

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit red light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the backlight further includes a second LED assembly including a second flexible light combiner; and

at least one of the first or second color LED is connected with the a light channel of the second LED assembly.

22. A head-mounted display (HMD), comprising:

a liquid crystal display (LCD) device, including;

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit red light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the light guide is disposed behind the LCD panel;

the LCD device further includes an eye cup disposed in front of the LCD panel; and

at least a portion of the flexible light combiner is wrapped around the eye cup such that the first and second LEDs are disposed along a surface of the eye cup.

23. A head-mounted display (HMD), comprising:

a liquid crystal display (LCD) device, including;

an LCD panel; and

a backlight for illuminating the LCD panel, the backlight including;

an LED assembly, including;

a first color LED emitting a first light at a first wavelength;

a second color LED emitting a second light at a second wavelength; and

a flexible light combiner, the flexible light combiner including a flexible core including;

a first light channel to transmit red light generated by the first color LED, a first end of the first light channel optically coupled with the first color LED;

a second light channel to transmit second light generated by the second color LED, a first end of the second light channel optically coupled with the second color LED; and

a light output terminal defined by second ends of the first and second light channels to output the first light and the second light in a first direction, the light output terminal disposed behind the LCD panel along an edge of the LCD panel; and

a light guide configured to;

combine the first light and second light received from the light output terminal of the flexible light combiner into combined light; and

direct the combined light to the pixels of the LCD panel in a second direction to illuminate the LCD panel;

wherein;

the first color LED has a lower efficiency than the second color LED; and

the display device further includes a controller configured to adjust for the first color LED having the lower efficiency than the second color LED based on providing a first control signal to drive the first color LED and a second control signal to the drive the second color LED, the first control signal including a higher current than the second control signal.