# Patent

## Title
Object-detecting backlight unit

## 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.

## Background
BACKGROUND
Display devices, such as televisions, laptop computers, tablet computers, and smart phones, may use a modulating display panel, such as a liquid crystal display, in combination with a backlight to display images to users. Increasingly, users want to use display devices that are interactive, such as devices equipped with touchscreen surfaces or cameras that capture user gestures. However, the region near, or just in front of, the display is not covered by touchscreen devices or cameras. For example, typical touchscreen devices capture data when the user physically touches, or is inherently close to touching, the display. Cameras, on the other hand, typically do not have a field of view that is wide enough to capture objects or user gestures close to the display. In addition, hardware costs may prohibit manufacturers from equipping some display devices, such as televisions, with a touchscreen or a camera.
SUMMARY
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.
This summary is provided to introduce simplified concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.



BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of techniques and apparatuses for implementing an object-detecting backlight unit are described with reference to the following drawings. The same numbers are used throughout the drawings to reference like features and components:
FIG. 1 illustrates an example environment in which an object-detecting backlight unit can be implemented.
FIG. 2 illustrates a detailed example of an object-detecting backlight unit and a display.
FIG. 3 illustrates another detailed example of an object-detecting backlight unit and a display.
FIG. 4 illustrates an example method for detecting a position of an object near a display using an object-detecting backlight unit.
FIG. 5 illustrates an example device in which techniques for an object-detecting backlight unit can be implemented.



DETAILED DESCRIPTION
Overview
As described above, users increasingly want to use display devices that are interactive, such as devices with touchscreen surfaces or cameras that capture user gestures. However, the region just in front of the display is not covered by touchscreen devices or cameras. For example, typical touchscreen devices capture data when the user physically touches, or is inherently close to touching, the display. Cameras, on the other hand, typically do not have a field of view that is wide enough to capture objects or gestures close to the display.
In a liquid crystal display (LCD), as commonly used in personal computers and televisions, light that passes through the LCD to form an image on the screen for the viewer is provided by a backlight unit. This document describes an object-detecting backlight unit that enhances the performance of backlight units for display devices. As described in more detail below, the object-detecting backlight unit is able to detect a position of an object near the display, as well as user gestures, such as swipes or wipes, near the display. In some embodiments, the object-detecting backlight unit is able to perform these tasks without modifying existing backlight units with any additional active components. Thus, unlike touchscreen displays which often require manufacturers to make the entire screen a touchscreen and add a digitizer to the device, manufacturers can modify conventional display devices with the object-detecting backlight unit without incurring additional hardware costs. In addition, the object-detecting backlight unit has low power and low processing overheads as compared with, for example, driving a camera and processing its output.
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.
Example Environment
FIG. 1 is an illustration of an example environment 100 in which an object-detecting backlight unit can be implemented. Environment 100 includes a display device 102, which is illustrated, by way of example and not limitation, as one of a smart phone 104, a laptop computer 106, a television device 108, a desktop computer 110, or a tablet computer 112.
Display device 102 includes processor(s) 114 and computer-readable media 116, which includes memory media 118 and storage media 120. Applications and/or an operating system (not shown) embodied as computer-readable instructions on computer-readable media 116 can be executed by processor(s) 114 to provide some or all of the functionalities described herein. Computer-readable media also includes controller 122. How controller 122 is implemented and used varies, and is described in further detail below.
Display device 102 also includes a backlight unit 124, which includes multiple light sources 126 and a light sensor 128. Light sources 126 are configured to inject light through a display 130 to form an image for viewing, such as a two-dimensional image, a three-dimensional image, or a multi-view image. In various embodiments, display 130 may be configured as a high resolution, flat-panel electronic display, such as a high-resolution liquid crystal display (LCD). An LCD is an electronically modulated optical device composed of liquid crystal display pixels positioned in front of a backlight unit to produce images.
Light sources 126 may include, by way of example and not limitation, light-emitting diodes (LEDs), compact cylindrical fluorescent light sources (CCFL), or any other type of light source configured for use in a display device. The number of light sources 126 may vary from two to four light sources for small display devices such as mobile phones, to 100 or more light sources for large display devices such as computer monitors or televisions. The output of backlight unit 124 can be controlled by either DC current control or by pulse-width modulation of light sources 126. Light sources 126 can be arranged electrically in combinations of series and parallel based on the power supply availability of display device 102.
Light sensor 128 is configured to detect light, such as light that originates from one of light sources 126, passes through display 130 to form an image for viewing, and is reflected back towards display 130 by an object near the display. In an embodiment, light sensor 128 is an ambient light detector that enables the brightness of display 130 to be controlled in proportion to external lighting conditions. An ambient light detector can be implemented as a single or dual silicon photodiode with subsequent signal conditioning.
As described in more detail below, backlight unit 124 is configured to detect a position of an object near the display without the use of a touchscreen or a camera. As described herein, an object is “near” the display if the object is positioned in front of the display, or if the object is positioned close enough to the display to be able to reflect light from the display back towards the display. In some embodiments, display device 102 may be configured with one or both of a touchscreen and a camera, and backlight unit 124 is configured to detect a position of objects near the display that are not physically touching the display and are too close to the display to be captured by the camera. In other embodiments, however, display device 102 may not be configured with either a touchscreen or a camera.
FIG. 2 illustrates a detailed example 200 of backlight unit 124 and display 130. In this example, display 130 is oriented horizontally. Alternately, however, display 130 may be oriented vertically, such as a screen of a typical television device. In this example, backlight unit 124 is configured with multiple light sources, two of which are identified as a first light source 202 and second light source 204, positioned along the base of display 130. It is to be noted, however, that backlight unit may be implemented with 100 or more light sources. Backlight unit 124 may use a variety of different configurations of light sources, such as a row of light sources positioned along the top of display 130, a row of light sources positioned along the top and the base of display 130, or a row of light sources positioned on the left and right sides of display 130.
In this example, first light source 202 is associated with a first region 206 on the right side of display 130, and second light source 204 is associated with a second region 208 on the left side of display 130. As described herein, a “region” can refer to any area on display 130, such as a right region of the display, a middle region of the display, a left region of the display, a top region of the display, or a bottom region of the display, to name just a few. A light source is considered to be “associated” with a particular region of display 130 if the light source projects light principally from that particular region of the display and/or if the light source is positioned in that particular region of the display.
In some embodiments, for example, backlight unit 124 is configured such that light from each light source emerges from the display in a way that approximately preserves the spatial distribution of each light source. In other words, light from the left-most light sources is principally projected from the left side of the display and light from the right-most light sources is principally projected from the right side of the display. In other embodiments, however, the light projected by each light source may be scrambled and diffused inside backlight unit 124 so as to make display 130 uniform in brightness. Such scrambling and diffusing, however, may cause light projected from one or more light sources on a left side of the display to be projected on the right side of the display, or vice versa. However, despite the scrambling and diffusing, a majority of the light projected on the left side of display will be from the light sources on the left side of the display, and a majority of the light projected on the right side of display will be from the light sources on the right side of display.
Continuing with example 200, display 130 receives light from first light source 202 and light from second light source 204. Display 130 then forms an image for viewing by projecting light 210 from first light source 202 out of first region 206 of display 130 and projecting light 212 from second light source 204 out of second region 208 of display 130.
FIG. 3 illustrates another detailed example 300 of backlight unit 124 and display 130. In this example, light 210 is reflected back towards display 130 as reflected light 302 when light 210 contacts an object 304, which in this case is a user's hand. Light sensor 128 receives reflected light 302, and backlight unit 124 determines whether reflected light 302 originated from first region 206 or second region 208 of display 130. It is to be noted that in conventional backlight units systems, the light sensor cannot discriminate between light that originated from different light sources or different regions of the display.
In accordance with various embodiments, to detect a position of objects positioned near the display, the output of at least two light sources of the backlight unit, each associated with a different region of the display, are modulated with different modulation functions. For instance, the output of at least two light sources can be modulated with sine waves with different frequencies. In this example, first light source 202 is modulated at a first frequency and second light source 204 is modulated at a second frequency. The frequencies can be invisible to the human eye (e.g., faster than 60 Hz). Further, the first frequency and the second frequency may be separated in frequency large enough to permit integration of the output with a time constant that is short compared with a likely speed of human interaction events, such as user's hand moving from one side of the display to the other to form a page-turn gesture. Light sensor 128 is configured to identify the light source or the region of the display from which the reflected light originated by demodulating the reflected light and comparing a frequency of the reflected light to the frequencies associated with the various light sources and regions of the display.
In an embodiment, backlight unit 124 may use an analog modulation scheme to modulate the light sources. Such modulation schemes are well known, and are not discussed in detail herein. In another embodiment, such as for cases where a large number of light sources are to be modulated, backlight unit 124 may use a digital modulation scheme in which each light source is driven by a binary function that is a member of an orthogonal set of functions, such as the Walsh functions.
In this example, because there are two described light sources, determining the light source from which the reflected light originated is the same as determining the region of the display from which the reflected light originated. However, in cases where backlight unit 124 includes more than two light sources, multiple light sources associated with a particular region of the display may be modulated with the same frequency. Light sensor 128, therefore, may be unable to determine the particular light source from which the reflected light originated, but will be able to determine a region of the display from which the light originated by virtue of the fact that all of the light sources within this region are modulated at the same frequency.
Continuing with the example above, backlight unit 124 determines the origin of reflected light 302 by demodulating the frequency of reflected light 302 and comparing the frequency of the reflected light to both the first frequency associated with first light source 202 and first region 206 of display 130, and to the second frequency associated with second light source 204 and second region 208 of display 130. In an embodiment, a photocurrent from light sensor 128 is amplified and band-pass filtered so as to provide two independent signal channels centered on the first frequency and the second frequency of the light sources. The signal channels are then rectified and integrated over a time period that is large compared to the first frequency and the second frequency, but short compared with human interaction timescales. This enables quick and low-computational-cost comparison of the frequency of the reflected light to the first frequency and the second frequency. In another embodiment, reflected light 302 can be demodulated using a digital modulation scheme, such as the Hadamard transform. For example, reflected light 302 can be demodulated using the Hadamard Transform, and data is clocked at the same clock rate as the basis frequency of the Walsh function used to modulate the light. It is to be appreciated, however, that other digital modulation schemes can be used to demodulate reflected light 302.
In another embodiment, backlight unit 124 determines the origin of reflected light 302 by demodulating reflected light 302 to determine an amplitude of the modulation function of reflected light 302. Then, backlight unit 124 compares the amplitude of the modulation function of reflected light 302 with an amplitude of the modulation function associated with first light source 202 and first region 206 of display 130, and with an amplitude of the modulation function associated with second light source 204 and second region 208 of display 130.
Continuing with example 300, after determining the region of display 130 from which reflected light 302 originated, backlight unit 124 can detect a position of object 304 relative to display 130. In this example, backlight unit 124 determines that object 304 is positioned in space relative to first region 206 of display 130 based on the determination that reflected light 302 originated from first region 206 of display 130. Thus, backlight unit 124 is able to detect a position of an object near display 130 without using a touchscreen or a camera.
Backlight unit 124 is further configured to determine a movement of an object near the display, such as movement from the right to the left side of display 130, from the left to the right side of display 130, from the top to the bottom of display 130, or from the bottom to the top of display 130. The ability to determine a movement of an object enables a user to perform various gestures to initiate corresponding events on display device 102. For instance, a user reading an electronic book rendered by display 130 may be able to move his hand from the right side to the left side of display 130 to initiate a page-turn gesture.
In FIG. 3, for example, object 304 moves from the right side to the left side of display 130. When this occurs, light 212 is reflected back towards display 130 as reflected light 306 when light 212 contacts object 304. Light sensor 128 receives reflected light 306, and backlight unit 124 determines whether reflected light 306 originated from first region 206 of display 130 or from second region 208 of display 130. Based on this determination, backlight unit 124 can detect an additional position of object 304 relative to display 130. In this example, backlight unit 124 can determine that object 304 is positioned in space relative to second region 208 of display 130 based on the determination that reflected light 306 originated from second region 208 of display 130.
Backlight unit 124 then determines a movement of the object based on the change in the position of the object. In this example, backlight unit 124 determines that object 304 moved from a position in space relative to first region 206 on the right side of display 130 to a position in space relative to second region 208 on the left side of display 130. Backlight unit 124 communicates the movement of object 304 to controller 122, which processes the movement to form a gesture. Controller 122 can then communicate the gesture to an operating system of display device 102 to initiate a variety of different events based on the gesture. For example, movement of the user's hand from the right side of display 130 to the left side of display 130 may be identified as a page-turn gesture for an electronic book, a volume-control gesture for an audio application, a channel-change gesture for a television application, a play-video gesture for a DVD application, to name just a few.
Backlight unit 124 may also be configured to identify movement of an object towards or away from display 130. In one embodiment, backlight unit 124 identifies movement of an object towards or away from the display 130 based on a change in the relative strength of the amplitude of reflected light. Continuing with the example above, if an amplitude of reflected light 302 is relatively stronger than an amplitude of reflected light 306, then display device 102 determines that object 304 is moving away from display 130. Alternately, if the amplitude of reflected light 302 is relatively weaker than the amplitude of reflected light 306, display device 102 determines that object 304 is moving closer to display 130.
Backlight unit 124 may also be configured to identify a speed of the movement of an object. Controller 122 may process the movement and the speed of the movement to form different gestures. For example, a rapid movement of the user's hand from the right side of display 130 to the left side of display 130 may be identified as chapter-change gesture, instead of just a page-turn gesture, for an electronic book. As another example, a rapid movement of the user's hand towards display 130 may be identified as a gesture to suppress information on display 130 for reasons of confidentiality. The speed of such rapid movements may be faster than the frame rate of a typical camera, however, in some embodiments backlight unit 124 is configured to respond to these movements within 10 milliseconds.
In one embodiment, backlight unit 124 is configured with at least a third light source 308 that is associated with a middle region of display 130 and is modulated at a third frequency. Third light source 308 enables backlight unit 124 to distinguish a variety of different gestures. For example, third light source 308 allows backlight unit to distinguish between a single object, such as a user's hand, moving from one side of the display to the other, and two objects, such as each of the user's hands, being positioned on either side of the display. In FIG. 3, for example, when object 304 moves from first region 206 on the right side of display 130 to second region 208 on the left side of display 130, additional reflected light (not pictured) from third light source 308 is reflected back towards display 130 and received by light sensor 128 before light sensor 128 receives reflected light 306 associated with second region 208 of display 130. This additional reflected light from third light source 308 indicates that object 304 crossed over the middle of display 130. Backlight unit 124, therefore, can determine that object 304 moved from first region 206 to second region 208 of display 130.
Alternately, if object 304 is positioned near first region 206 on the right side of display 130, and an additional object is positioned near second region 208 on the left side of display 130, light sensor 128 receives reflected light 302 associated with first region 206 as well as reflected light 306 associated with second region 208 of display 130. However, because light sensor 128 does not receive reflected light corresponding to third light source 308 in the middle of display 130, backlight unit 124 can determine that an object did not move from one side of the display to the other, and therefore determine that two objects are near the display.
Example Method
FIG. 4 is flow diagram depicting an example method 400 for detecting a position of an object near a display using an object-detecting backlight unit. Block 402 receives reflected light when an object is near a display. For example, light sensor 128 (FIG. 3) receives reflected light 302 when object 304 is near display 130. The reflected light is caused by light from an image being rendered by the display reflecting off of the object, such as reflected light 302 reflecting off of object 304.
Block 404 determines that the reflected light originated from a region of the display based on a frequency of the reflected light being equal to a frequency associated with the region of the display. For example, backlight unit 124 determines that reflected light 302 originated from first region 206 of display 130 based on a frequency of reflected light 302 being equal to a frequency associated with first region 206 of display 130.
Block 406 detects a position of the object as being positioned in space relative to the region of the display. For example, backlight unit 124 detects a position of object 304 as being positioned in space relative to first region 206 of display 130 based on reflected light 302 originating from first region 206 of display 130.
Block 408 receives additional reflected light when the object is near the display. For example, light sensor 128 receives reflected light 306 when object 304 is near display 130. In this example, the additional reflected light is caused by object 304 moving from first region 206 on the left side of display 130 to second region 208 on the right side of display 130.
Block 410 determines that the additional reflected light originated from an additional region of the display based on an additional frequency of the reflected light being equal to an additional frequency associated with the additional region of the display. For example, backlight unit 124 determines that reflected light 306 originated from second region 208 of display 130 based on a frequency of reflected light 306 being equal to a frequency associated with second region 208 of display 130.
Block 412 detects an additional position of the object as being positioned in space relative to the additional region of the display. For example, backlight unit 124 detects an additional position of object 304 as being positioned in space relative to second region 208 of display 130 based on reflected light 306 originating from second region 208 of display 130.
Block 414 determines a movement of the object based on a change between the position and the additional position of the object. For example, backlight unit 124 determines a movement of object 304 based on a change between object 304 being positioned on the right side of the display and then the left side of the display. In some embodiments, backlight unit 124 can then communicate the movement of object 304 to controller 122, which processes the movement to form a gesture. Controller 122 can then communicate the gesture to an operating system of display device 102 to initiate a variety of different events. For example, movement of the user's hand from the right side of display 130 to the left side of display 130 may be identified as a page-turn gesture for an electronic book, a volume-control gesture for an audio application, a channel-change gesture for a television application, or a play-video gesture for a DVD application.
Example Device
FIG. 5 illustrates various components of example device 500 that can be implemented as any type of client, server, and/or display device as described with reference to the previous FIGS. 1-4 to implement techniques enabling an object-detecting backlight unit. In embodiments, device 500 can be implemented as one or a combination of a wired and/or wireless device, as a form of flat panel display, television, television client device (e.g., television set-top box, digital video recorder (DVR), etc.), consumer device, computer device, server device, portable computer device, user device, communication device, video processing and/or rendering device, appliance device, gaming device, electronic device, and/or as another type of device. Device 500 may also be associated with a viewer (e.g., a person or user) and/or an entity that operates the device such that a device describes logical devices that include users, software, firmware, and/or a combination of devices.
Device 500 includes communication devices 502 that enable wired and/or wireless communication of device data 504 (e.g., received data, data that is being received, data scheduled for broadcast, data packets of the data, etc.). The device data 504 or other device content can include configuration settings of the device, media content stored on the device, and/or information associated with a user of the device. Media content stored on device 500 can include any type of audio, video, and/or image data. Device 500 includes one or more data inputs 506 via which any type of data, media content, and/or inputs can be received, such as user-selectable inputs, messages, music, television media content, recorded video content, and any other type of audio, video, and/or image data received from any content and/or data source.
Device 500 also includes communication interfaces 508, which can be implemented as any one or more of a serial and/or parallel interface, a wireless interface, any type of network interface, a modem, and as any other type of communication interface. The communication interfaces 508 provide a connection and/or communication links between device 500 and a communication network by which other electronic, computing, and communication devices communicate data with device 500.
Device 500 includes one or more processors 510 (e.g., any of microprocessors, controllers, and the like), which process various computer-executable instructions to control the operation of device 500 and to enable techniques for implementing an object-detecting backlight unit. Alternatively or in addition, device 500 can be implemented with any one or combination of hardware, firmware, a system-on-chip (SoC), or fixed logic circuitry that is implemented in connection with processing and control circuits which are generally identified at 512. Although not shown, device 500 can include a system bus or data transfer system that couples the various components within the device. A system bus can include any one or combination of different bus structures, such as a memory bus or memory controller, a peripheral bus, a universal serial bus, and/or a processor or local bus that utilizes any of a variety of bus architectures.
Device 500 also includes computer-readable storage media 514, such as one or more memory devices that enable persistent and/or non-transitory data storage (i.e., in contrast to mere signal transmission), examples of which include random access memory (RAM), non-volatile memory (e.g., any one or more of a read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, EPROM, EEPROM, etc.), and a disk storage device. A disk storage device may be implemented as any type of magnetic or optical storage device, such as a hard disk drive, a recordable and/or rewriteable compact disc (CD), any type of a digital versatile disc (DVD), and the like. Device 500 can also include a mass storage media device 516.
Computer-readable storage media 514 provides data storage mechanisms to store the device data 504, as well as various device applications 518 and any other types of information and/or data related to operational aspects of device 500. For example, an operating system 520 can be maintained as a computer application with the computer-readable storage media 514 and executed on processors 510. The device applications 518 may include a device manager, such as any form of a control application, software application, signal-processing and control module, code that is native to a particular device, a hardware abstraction layer for a particular device, and so on.
The device applications 518 also include any system components or modules to implement techniques using or enabling an object-detecting backlight unit. In this example, the device applications 518 can include controller 122 for controlling and/or receiving data from an object-detecting backlight unit.
CONCLUSION
This document describes various apparatuses and techniques for implementing an object-detecting backlight unit. Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as example forms of implementing the claimed invention.

## 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.

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.

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.