Object-detecting backlight unit

• US 9,256,089 B2
• Filed: 06/15/2012
• Issued: 02/09/2016
• Est. Priority Date: 06/15/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Emerton, Neil, Large, Timothy Andrew, Boulanger, Catherine N.
• Primary Examiner(s): Hicks, Charles
• Assistant Examiner(s): Castiaux, Brent D
• Application Number:
  US13/525,070
• Publication Number:
  US 20130335387A1
• Time in Patent Office: 1,334 Days
• Field of Search: 345/207, 250/206.1, 349/61
• US Class Current: 1/1
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

This document describes techniques and apparatuses for implementing an object-detecting backlight unit for a display device. An object-detecting backlight unit includes two or more light sources configured to provide light to a display to form an image, and a light sensor configured to receive reflected light when an object is near the display and determine that the reflected light originated from a region of the display. The reflected light is caused by light from the image reflecting off of the object back towards the display. The backlight unit is configured to detect a position of the object based on the region of the display from which the reflected light originated.

Claims

1. A display device comprising:

a backlight unit comprising at least a light sensor, a first light source modulated at a first frequency and associated with a first region of a display, a second light source modulated at a second frequency and associated with a second region of the display, and a third light source modulated at a third frequency and associated with a third region of the display;

the display configured to receive light from the first light source, the second light source, and the third light source and to form an image for viewing by projecting the light from the first light source out of the first region of the display, projecting the light from the second light source out of the second region of the display, and projecting the light from the third light source out of the third region of the display; and

the light sensor of the backlight unit configured to receive reflected light from the image formed by the display when an object is near the display and determine whether the reflected light originated from the first region, the second region, or the third region of the display by demodulating the reflected light and comparing a frequency of the reflected light to the first frequency, the second frequency, and the third frequency, the backlight unit configured to detect a position of the object relative to the display based on whether the reflected light originated from the first region, the second region, or the third region of the display, the third region of the display comprising a middle region of the display.

2. A display device as described in claim 1, wherein the backlight unit is further configured to:

detect the position of the object as being positioned in space relative to the first region of the display if the reflected light originated from the first region of the display; and

detect the position of the object as being positioned in space relative to the second region of the display if the reflected light originated from the second region of the display.

3. A display device as described in claim 1, wherein the backlight unit is further configured to determine a movement of the object based on a change between the position of the object and an additional position of the object.

4. A display device as described in claim 3, wherein the backlight unit is further configured to communicate the movement of the object to a controller to initiate the controller processing the movement to form a gesture.

5. A display device as described in claim 4, wherein the gesture comprises one of a page-turn gesture, a volume-control gesture, or a channel-change gesture.

6. A display device as described in claim 1, wherein the display comprises a liquid crystal display (LCD).

7. A display device as described in claim 1, wherein the light sensor comprises an ambient light detector.

19. A display device as described in claim 1, wherein the first frequency and the second frequency are invisible to the human eye.

20. A display device as described in claim 1, wherein the first region of the display comprises one of a left region, a right region, a top region, or a bottom region of the display, and wherein the second region of the display comprises a different one of the left region, the right region, the top region, or the bottom region of the display.

8. A method comprising:

receiving reflected light when an object is near a display, the reflected light comprising light from an image being rendered by the display reflecting off of the object;

determining whether the reflected light originated from a first region of the display, a second region of the display, or a third region of the display based on a frequency of the reflected light being equal to a first frequency associated with the first region of the display, a second frequency associated with the second region of the display, or a third frequency associated with the third region of the display; and

detecting a position of the object as being positioned in space relative to the first region of the display responsive to determining that the frequency is equal to the first frequency, the first region of the display, the second region of the display, and the third region of the display each corresponding to respective areas on the display, at least one of the first, second, or third regions of the display comprising a middle region of the display.

9. A method as described in claim 8, wherein determining whether the reflected light originated from the first region of the display, the second region of the display, or the third region of the display further comprises:

demodulating the reflected light to determine the frequency of the reflected light; and

comparing the frequency of the reflected light to the first frequency associated with the first region of the display, the second frequency associated with the second region of the display, and the third frequency associated with the third region of the display.

10. A method as described in claim 8, further comprising:

receiving additional reflected light when the object is near the display;

determining whether the additional reflected light originated from the first region of the display or the second region of the display based on an additional frequency of the additional reflected light being equal to the first frequency associated with the first region of the display or the second frequency associated with the second region of the display;

detecting an additional position of the object as being positioned in space relative to the second region of the display responsive to determining that the additional frequency is equal to the second frequency; and

determining a movement of the object based on a change between the position and the additional position of the object.

11. A method as described in claim 10, further comprising processing the movement of the object to form a gesture, and communicating the gesture to initiate an event.

12. A method as described in claim 8, wherein determining the movement of the object further comprises:

determining that the object is moving away from the display if an amplitude of the reflected light is relatively stronger than an additional amplitude of the additional reflected light; and

determining that the object is moving towards the display if the amplitude of the reflected light is relatively weaker than the additional amplitude of the additional reflected light.

13. A method as described in claim 8, wherein the first region of the display comprises one of a left region of the display, a right region of the display, a top region of the display, or a bottom region of the display, and wherein the second region of the display comprises a different one of the left region of the display, the right region of the display, the top region of the display, or the bottom region of the display.

14. A backlight unit comprising:

three or more light sources configured to provide light to a display to form an image;

a light sensor configured to receive reflected light when an object is near the display and determine that the reflected light originated from a first region of the display, a second region of the display, or a third region of the display based on a comparison of a frequency of the reflected light to a first frequency associated with a first region of the display, a second frequency associated with the second region of the display, and a third frequency associated with a third region of the display, the reflected light comprising light from the image reflecting off of the object; and

the backlight unit configured to detect a position of the object based on the region of the display from which the reflected light originated, the first region of the display, the second region of the display, and the third region of the display each corresponding to respective areas on the display, at least one of the first, second, or third regions of the display comprising a middle region of the display.

15. A backlight unit as described in claim 14, wherein the light sensor is configured to determine that the reflected light originated from the region of the display by:

demodulating the reflected light to determine the frequency of the reflected light;

comparing the frequency of the reflected light to the first frequency associated with the first region of the display and to the second frequency associated with the second region of the display; and

determining that the reflected light originated from the first region of the display based on the frequency of the reflected light being equal to the first frequency associated with the first region of the display and determining that the reflected light originated from the second region of the display based on the frequency of the reflected light being equal to the second frequency associated with the second region of the display.

16. A backlight unit as described in claim 14, wherein the three or more light sources comprise three or more light-emitting diodes (LEDs).

17. A backlight unit as described in claim 14, wherein the display comprises a liquid crystal display (LCD).

18. A backlight unit as described in claim 14, wherein the light sensor comprises an ambient light detector.