Backlight unit, 3D display having the same, and method of forming 3D image

A backlight unit of a three-dimensional (3D) display has a plurality of cells and a 3D image is formed by adjusting directions of light emitted from the cells. The backlight unit includes an emission unit that adjusts an emission direction of light from a cell with respect to other cells. The backlight unit divides view areas to provide left-eye and right-eye images, thereby generating a 3D image.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. 119 to Korean Patent Application No. 10-2010-0029351, filed on Mar. 31, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

The following description relates to a backlight unit, a three-dimensional (3D) display having the same, and a method of forming a 3D image. More particularly, direction of light emitted by the backlight unit may be adjustable.

2. Description of the Related Art

Three-dimensional (3D) images can be formed according to the principle of stereo visualization in a viewer's eyes. An important factor in generating a stereoscopic sensation in 3D images is the binocular parallax which occurs due to the distance between two eyes of the viewer (i.e. about 65 mm). There are generally two different types of conventional three-dimensional (3D) image displays. A first type of 3D image display requires suitable glasses to see 3D images on the display, and a second type of 3D image display does not require glasses to view 3D images. In the second type of 3D image displays, 3D images can be generated by separating right images and left images without using glasses. Techniques for the 3D image displays without 3D glasses include a parallax barrier method and a lenticular method.

In the parallax barrier method, images to be observed by right and left eyes are alternately displayed, where each image has longitudinal patterns, and the images are observed using a very thin longitudinal lattice row, e.g., a barrier. In this way, a longitudinal pattern image for the left eye and a longitudinal pattern image for the right eye are separated by the barrier. The image for the left eye and the image for the right eye have different view points, and thus they are separately observed by the right and left eyes, respectively, to form a stereoscopic image.

In the lenticular method, images corresponding to right and left eyes are disposed on a focal plane of a lenticular lens, and the images are observed through the lenticular lens. The images corresponding to the right and left eyes are divided based on the characteristic of the lenticular lens, and thus they are separately observed by the right and left eyes, respectively, to form a stereoscopic image.

In both the parallax barrier method and the lenticular method, a stereoscopic image viewing area is fixed because a barrier or lens, a focal length, an emission direction, and the like are fixed. For example, a 3D image can be viewed only either in a landscape/horizontal mode or in a portrait/vertical mode of a display in the parallax barrier and lenticular methods. This is because the barrier and lenticular lens are arranged such that only a certain display direction and orientation provides images that the right and left eyes can properly observe in order to form a stereoscopic image.

SUMMARY

In one general aspect, a backlight unit includes a plurality of cells, each of the plurality of cells being adapted to direct light in two or more emission directions, wherein a first image is displayed when the light is directed in one of the two or more emission directions, and wherein a second image is displayed when the light is directed in another of the two or more emission directions.

Each of the plurality of cells may include a plurality of light sources. The plurality of light sources may be arranged in two-dimensional array. Each of the plurality of light sources may be controlled independently.

Each of the plurality of cells includes a plurality of reflection portions, and each of the plurality of light sources may be arranged to correspond to each of the plurality of reflection portions.

The plurality of reflection portions may be arranged on a curved surface.

Each of the plurality of cells further may include a pin hole, wherein the pin hole is disposed in a position above the plurality of light sources.

The pin hole may affect an emission direction of light emitted from each of the plurality of light sources, and each of the emission directions of the plurality of light sources are different from one another.

The backlight units may include at least one light guide plate (LGP), and a light source emitting light into a surface of the light guide plate (LGP). The light guide plate (LGP) may be formed in a wedge shape. Each of the plurality of cells may include a prism array disposed above the light guide plate (LGP). The prism array may include an electric wetting device.

The prism array may include a plurality of prisms, wherein the plurality of prisms are arranged in a two-dimensional manner and each of the plurality of prisms is controlled independently.

Each of the plurality of cells may further include a shutter array disposed above the light guide plate (LGP).

The shutter array may include at least one selected from the group of an electric wetting shutter, a liquid crystal shutter, a frustrated total internal reflection (FTIR) shutter, and any combination thereof.

The prism array may further include a plurality of prisms, wherein the plurality of prisms are arranged in a two-dimensional manner and each of the plurality of prisms is operated independently.

According to another general aspect, a three-dimensional (3D) display includes a backlight unit and a display panel disposed above the backlight unit, wherein the backlight unit includes a plurality of cells, each of the plurality of cells being able to direct light in two or more emission directions, wherein a first image is displayed when the light is directed in a first emission direction of the two or more emission directions, and wherein a second image is displayed when the light is directed in a second emission direction of the two or more emission directions.

Each of the plurality of cells may further include a plurality of light sources, wherein each of the plurality of light sources is controlled independently. Each of the plurality of cells may further include a plurality of reflection portions arranged on a curved surface. Each of the plurality of cells may further include a pin hole, wherein the pin hole affects an emission direction of light emitted from at least one of the plurality of light sources.

The backlight unit may further include a light guide plate (LGP), and the backlight unit may also further include at least one selected from the group of a prism array, a shutter array disposed above the light guide plate (LGP), and any combination thereof. The at least one selected from the group of the prism array, the shutter array, and any combination thereof may include an electric wetting device.

According to another general aspect, a method of forming a three-dimensional (3D) image includes calculating an emission direction of light of each of a plurality of cells in a backlight unit, wherein each of the plurality of cells are adapted to direct light in at least two different emission directions, providing a first image with light directed in one of the at least two different emission directions, and providing a second image with light directed in another of the at least two different emission directions.

Each of the plurality of cells may include a plurality of light sources arranged in a two-dimensional manner, and each of the plurality of light sources may be controlled independently.

The method may further include adjusting an emission direction of light of at least one of the plurality of cells according to the calculated emission direction by selectively turning ON or OFF each of the plurality of light sources.

Each of the plurality of cells may include at least one selected from the group of a pin hole, a plurality of reflection portions, and any combination thereof.

The backlight unit may include a light guide plate (LGP), and the backlight unit may further include at least one selected from the group of a prism array, a shutter array disposed above the light guide plate (LGP), and any combination thereof.

The method may further include adjusting an emission direction of light of at least one of the plurality of cells according to the calculated emission direction by independently operating at least one selected from the group of prisms of the prism array, shutters of the shutter array, and any combination thereof.

The method may further include determining an orientation of a display apparatus that includes the backlight unit, wherein the providing the first image may further include directing light in the one of the at least two different emission directions according to the determined orientation of the display apparatus, and wherein the providing the second image may further include directing light in the another of the at least two different emission directions according to the determined orientation of the display apparatus.

The orientation of the display apparatus may be determined according to the detection result of a gravity sensor. The orientation of the display apparatus may be determined according to tracking information of a user's right eye and left eye.

In another general aspect, a three-dimensional (3D) display includes a backlight unit, a display panel disposed above the backlight unit, and a sensing unit for determining the orientation of the 3D display, wherein the backlight unit includes a plurality of cells, each of the plurality of cells being able to direct light in a plurality of emission directions, wherein a first image is displayed when the light is directed in a first emission direction of the plurality of emission directions according to an output result of the sensing unit, and wherein a second image is displayed when the light is directed in a second emission direction of the plurality of emission directions according to an output result of the sensing unit.

Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements, as well as the thicknesses of layers and regions, may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader in gaining an understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein may be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness.

Specific structural and functional details described herein are merely representative for purposes of describing certain examples. Thus, the features described herein may be embodied in many alternate forms and should not be construed as limited to only the examples set forth herein. Therefore, it should be understood that there is no intent to limit the examples to the particular forms described, but on the contrary, the examples are provided are to cover all modifications, equivalents, and alternatives falling within the scope of the invention.

It should also be noted that in some alternative implementations, the functions or operations may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functions or operations involved.

According to the examples described herein, a three-dimensional (3D) display includes a backlight unit that adjusts a light emission direction to provide a left-eye view area and a right-eye view area separately for a 3D image.FIG. 1illustrates a schematic view of a 3D display according to certain examples described herein. The 3D display may include a backlight unit10and a display panel20that may generate an image by using the light emitted from the backlight unit10. The backlight unit10may include a plurality of cells Z11, . . . , and Zmn, and each of the plurality of cells Z11, . . . , and Zmnincludes an emission unit15that may adjust a light emission direction of the cell. As an example, the cells Z11, . . . , and Zmnmay be arranged in a two-dimensional manner. The display panel20includes a plurality of pixels and generates images according to light transmitted through each of the pixels. As an example, the display panel20may be a liquid crystal display (LCD) panel.

FIG. 2illustrates a cross-sectional view ofFIG. 1taken along a line II-II. Referring toFIG. 2, the emission unit15of each cell Zijmay adjust the light emission direction independently and optionally. Therefore, the light emitted from each cell can be directed to a left eye LE, a right eye RE, or both left and right eyes. When the light is selectively transmitted to the left eye LE or the right eye RE, a 3D image can be generated. On the other hand, when the light is transmitted to both left eye LE and right eye RE, a 2D image can be generated. In this manner, the 3D display illustrated inFIG. 1can be converted from a 3D display mode to a 2D display mode, and vice versa. Further, the emission unit15may adjust the light emission direction in a vertical direction, a horizontal direction, or a diagonal direction. Therefore, the 3D images on the 3D display of the examples described herein may be displayed in various orientations by adjusting the light emission direction of each emission unit15independently. For example, the emission unit15may be changed from a landscape mode, in which a 3D image can be viewed when a display is disposed in a horizontal direction, to a portrait mode, in which a 3D image can be viewed when a display is disposed in a vertical direction.

In the 3D display illustrated inFIG. 2, a view area of the display may be divided to provide a left-eye image and a right-eye image separately by adjusting the light emission direction of the backlight unit10. The left-eye image and the right-eye image are displayed sequentially to provide a 3D image while avoiding a reduction in image resolution.

FIG. 3illustrates an example of a backlight unit100. The backlight unit100ofFIG. 3may include a plurality of cells, and each of the plurality of cell may have an emission unit115that adjusts the light emission direction with respect to the emission units of other cells. The plurality of cells may include a first cell115a, a second cell115b, and a third cell115c. The plurality of cells may be arranged in a 2D manner, and each cell may be formed to be substantially square and substantially point symmetric. Further, the number and sizes of cells may be changed according to the size of a display, the number of pixels, resolution, and the like.

The emission unit115includes a plurality of reflection portions120and a plurality of light sources125. Each light source125may be disposed with respect to a corresponding reflection portion120, as illustrated inFIG. 3. Each of the reflection portions120may have a curved shape and is be formed of a material that reflects light emitted from the light sources125. Each of the plurality of light sources125includes a lighting element (e.g. light emitting diode (LED), an organic light emitting diode (OLED), and the like). The reflection portions120may be arranged in a 3D structure within each of the cells115a,115b, and115c. For example, the reflection portions120may be arranged in a curved surface as shown inFIG. 3. Since the reflection portions120may face different directions from one another, lights reflected by the reflection portions120may be directed to different directions. Each of the reflection portions120may have a point symmetry structure.

In each of the cells115a,115b, and115c, the light sources125may be selectively turned on or off; thus, the light emission direction of the light from each cell can be changed. For example, to achieve a certain light emission direction, a first light source may be turned on in the first cell115a, a third light source may be turned on in the second cell115b, and a fifth light source may be turned on in the third cell115cas illustrated inFIG. 3. Thus, the light emission direction in each of the cells may be adjusted independently. The light emission direction of each of the cells115a,115b, and115cmay be set according to the position of a light source125which is turned on. A control unit (not shown) of a display may have information regarding light sources125and corresponding light emission directions in each of the cells115a,115b, and115c. According to the above example, the light emission directions of the cells115a,115b, and115care based on the arrangement of the reflection portions120. Further, the light emission directions may be controlled in various directions, including a vertical direction, a horizontal direction, a diagonal direction, and the like.

The reflection portions120may be paraboloidal mirrors in which a light source125is located at the focus of a corresponding reflection portion120, and thus light emitted from any light source125is reflected and collimated by the corresponding reflection portion120, due to the parabolic shape. Centers of the light sources125disposed within the corresponding reflection portions120may be connected by a virtual line130. Virtual line130may be disposed as a curved line. Accordingly, the light emission direction may be adjusted based on the positions of the light sources125that are turned on and the orientations of the corresponding reflection portions120. Light emitted from the cells may be transmitted in a corresponding left-eye direction and a corresponding right-eye direction to provide a 3D image.

According to the above example, the 3D image may be displayed without reducing the resolution of the observed image by displaying the left-eye image and the right-eye image in a temporal sequence. In other words, the light sources125may be selectively turned on in each of the cells of the backlight unit100to provide an emission light in the left-eye direction only, and thus only a left-eye image is formed in a display panel for a first frame. For a second frame, the light sources125may be selectively turned on in each of the cells of the backlight unit100to provide an emission light in a right-eye direction only, and thus only a right-eye image is formed in the display panel for the second frame.

According to the above example, a 2D image may be displayed on the 3D display by turning on the light sources125disposed in the same position in each of the cells, for example the light sources that are positioned in the center of each of the cells and provide light into a direction substantially perpendicular to the display panel. Therefore, the image formed on the display may be converted from 3D to 2D and vice versa by adjusting the light emission direction in each of the cells.

FIG. 4illustrates another example of a backlight unit200. Referring toFIG. 4, the backlight unit200includes a light source205, a light guide plate (LGP)210guiding light emitted from the light source205, and a prism array220disposed above the LGP210. The prism array220operates as an emission unit to adjust the light emission direction of the light guided by the LGP210. The light source205may be a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), an organic light emitting diode (OLED), or the like. The LGP210guides light emitted from the light source205towards the prism array220. The LGP210may collimate lights from a point light source or linear light source and may provide a surface light source for the prism array220. The LGP210may have a wedge shape, as illustrated inFIG. 4, so as to facilitate collimation of light. Further, the LGP210may include prism patterns disposed on a top surface or a bottom surface to facilitate collimation of the light emitted from the light source205. The prism patterns may be formed on the LGP210through one of well-known technologies in the industries, or through a process specially designed for implementing the above-described features.

According to the above example, the prism array220disposed on the LGP210is divided into cells225. A prism in each cell includes a refraction surface230whose inclination may be adjusted by an electrical signal. Therefore, the emission direction of light from each cell may be adjusted by changing the inclination of the refractive surface230of the prism located in the cell. For example, the cells225include a first cell225a, a second cell225b, and a third cell225c. The refraction surfaces230in the first cell225a, the second cell225b, and the third cell225cmay be adjusted independently to control light emission directions of the lights from the first, second and third cells separately. The controlled light emission directions may be directed to a left eye view or a right eye view, and thus a 3D image may be displayed.

The prism array220, for example, may include an electric wetting device. The cells of the prism array220may be divided by electrodes207. A polarizable liquid229(e.g. water) and a nonpolar liquid231(e.g. oil) may be filled between the electrodes207. A boundary surface formed between the polarizable liquid229and the nonpolar liquid231acts as a refraction surface230. A dielectric layer208may be disposed on inner walls of the electrodes207. The dielectric layer208has a hydrophobic surface formed by coating a hydrophobic thin film on a top surface of the dielectric layer or by using a hydrophobic dielectric layer. According to the above example, the polarizable liquid229may be inclined at a high contact angle with the dielectric layer208when voltage is not applied to the electrodes207. On the other hand, the contact angle between the dielectric layer208and the polarizable liquid229is decreased when voltage is applied to the electrodes207. Therefore, the inclination of each refraction surface230can be adjusted by the electrical voltage. The variation of inclination of the refractive surface230changes the light emission direction of the light from the cell. Accordingly, the light emission direction may be adjusted by the voltage supply to the electrodes207where the voltage supply can be controlled by ON and OFF switching process or by controlling magnitudes of voltage. The mechanism for adjusting the light emission directions of the cell in this example is not limited to the principle of electric wetting. For example, the light emission direction may also be adjusted by using a liquid crystal when an image is formed by using polarized light. In the liquid crystal, the arrangement of liquid crystal molecules is varied according to the size/strength of an electric field formed by applied voltages, which provides a variation of the refractivity of the liquid crystal.

According to the example illustrated inFIG. 4, the light emission direction may be adjusted according to magnitudes and directions of the voltages applied to the prism array220. For example, a light emission at a first time t1may be transmitted in a left eye direction, and a light emission at a second time t2may be transmitted in a right eye direction by adjusting the applied voltages, thereby providing a 3D image. Since the left-eye image and the right-eye image may be displayed sequentially, the 3D image can be displayed without reducing the resolution of the displayed image. A 2D image may also be displayed in the 3D display by adjusting the light emission direction in each of the cells in such a way that light emitted from each of the cells is directed in substantially the same direction, such as perpendicular to the front side of a display panel placed above the backlight unit200. Thus, the display mode of the 3D display according to the above example can be switched from a 3D display mode to a 2D display and vice versa.

FIG. 5illustrates another example of a backlight unit300. Referring toFIG. 5, the backlight unit300includes a plurality of cells, and each of the cells includes an emission unit325that adjusts the direction of light emitted from the corresponding cell. The emission unit325includes a light array selectively transmitting light and a direction adjusting portion for controlling emission direction of the light emitted from the light array. The light array may include a light source305, an LGP310that guides light emitted from the light source305, and a shutter array327disposed over the LGP310. A lens array330disposed over the shutter array327may control the direction of light passed through the shutter array327.

The light source305may be a CCFL, an LED, an OLED, or the like. The LGP310may include scattering emission patterns.

According to the example illustrated inFIG. 5, the shutter array327may include a plurality of shutters for each of the cells. The plurality of shutters in each cell may be arranged in a 2D manner, and each cell may be formed to be substantially square and substantially point symmetric. For example, the shutter array327may include first through fifth shutters327a,327b,327c,327d, and327ein the first cell325a. The first through fifth shutters327a,327b,327c,327d, and327emay be formed as a liquid crystal shutter, an electric wetting shutter, a frustrated total internal reflection (FTIR) shutter (hereinafter, referred to as an FTIR shutter), and the like. The FTIR shutter may be employed to reduce power consumption, as compared to other shutters, by recycling light.

The lens array330may include a plurality of lenses corresponding to each of the cells, and the shutter array327may be disposed on a focal plane of the lens array330. For example, when the cells are arranged in a 2D manner, the lens array330may also be arranged in a 2D manner. A space layer329may be further formed between the lens array330and the shutter array327so as to separate the lens array330from the shutter array327by a distance substantially equal to a focal length of the lens. The space layer329may be formed of a material having the same or a similar refractive index as that of the lens array330or of the space layer329. Also, the lens array330may form a unitary body made from the same or similar lens material. According to the example illustrated inFIG. 5, the backlight unit300may further include a diffusion plate312that substantially uniformly disperses light emitted from the LGP310, a prism sheet314that alters a light proceeding path, and/or a brightness enhancement film316. Diffusion plate312, prism sheet314, and brightness enhancement film316may each be disposed between the shutter array327and the LGP310.

According to the example illustrated inFIG. 5, light emitted from the light source305(e.g. substantially a point or line light source) is converted to a planar slight source by dispersing the light over a surface of the backlight unit300through the LGP310. Light emitted from the LGP310may be controlled by ON and OFF switching operations of the shutter array327. The direction of light passed through the shutter array327may vary according to positions of the opened shutters in the cells and interactions with the lens array330. For example, when the first shutter327ais opened and the remaining second through fifth shutters327b,327c,327d, and327eare closed in the first cell325a, the light controlled by the shutter array327is directed in an upward-right direction as illustrated inFIG. 5. On the other hand, when the fifth shutter327eis opened and the remaining first through fourth shutters327a,327b,327c, and327dare closed as shown in the third cell325cofFIG. 5, the light is directed in an upward-left direction. When the third shutter327cis opened and the remaining first, second, fourth, and fifth shutters327a,327b,327d, and327eare closed as illustrated in the second cell325bofFIG. 5, the light is directed in a substantially upward/vertical direction. Therefore, a 3D image can be displayed with a left-eye view area and a right-eye view area, which are each obtained by adjusting the emission direction of light in each of the cells. According to the example illustrated inFIG. 5, the emission direction of light from each cell may be adjusted independently and controlled in various directions, according to different combinations of the position of the opened shutter and the position of lens corresponding to the opened shutters. When the shutter array327of the above example is arranged in a 2D manner, the light emission direction may be freely adjusted in vertical and horizontal directions as well as right and left directions, relative to an initial orientation of the display. Accordingly, a display having the backlight unit300may display 3D images in various orientations including a portrait display method and a landscape display method. Further, by displaying a left-eye image and a right-eye image in a temporal sequence, the 3D image may be displayed without reducing the resolution of the observed image.

According to the example illustrated inFIG. 5, a 2D image may also be provided in a display by adjusting the emission direction of light from the cells by controlling the positions of the opened shutter in the backlight unit300. For example, by opening all of shutters of the shutter array327or by opening shutters in the same position in each of the cells, a 2D image may be displayed. In this manner, an image on the display may be converted from a 2D image to a 3D image and vice versa by controlling the opened shutters of the shutter array327.

FIG. 6illustrates another example of a backlight unit400. Referring toFIG. 6, the backlight unit400includes a plurality of cells430, and each of the cells includes an emission unit420that adjusts a light emission direction with respect to each of the cells430. The emission unit420includes a light source array415, in which a plurality of light sources are arranged, and a pin hole425disposed over the light source array415. The light source array415may include an LED or OLED. One pin hole425may be formed for each of the cells430. The light source array415may be implemented as a light array in which each of light sources may be turned ON or OFF. In comparison with the backlight unit300shown inFIG. 5, the light source305, the LGP310, and the shutter array327of the backlight unit300may be replaced with the light source array415ofFIG. 6, and the light source array415provides an array of light emissions. The light source array415may be arranged in a 2D manner, and each cell may be formed to be substantially square and substantially point symmetric. As an example, the light source array415may include a plurality of light sources, a first through a fifth light source415a,415b,415c,415d, and415e. According to the example illustrated inFIG. 6, a light emission direction of each cell may be controlled by a position of a light source that is turned ON, being one of the first through fifth light sources415a,415b,415c,415d, and415eof the light source array415, and the pin hole425of the cell, which affects the direction of light emitted from the turned ON light source.

For example, the plurality of cells430may include a first cell430a, a second cell430b, and a third cell430c. When the first light source415aof the first cell430ais turned ON and the remaining second through fifth light sources415b,415c,415d, and415eare turned OFF in the first cell430a, light emitted from the first light source415ais directed in an upward-right direction the pin hole425of the first cell430aas illustrated inFIG. 6. On the other hand, when the fifth light source415eis turned ON and the remaining first through fourth light sources415a,415b,415c, and415dare turned OFF as shown in the third cell430cofFIG. 6, light emitted from the fifth light source is directed in an upward-left direction through the pin hole425of the third cell430c. When the third light source415cis turned ON and the remaining first, second, fourth, and fifth light sources415a,415b,415d, and415eare turned OFF as show in the second cell430bofFIG. 6, light emitted from the third light source415cis directed in a substantially upward/vertical direction via the pin hole425of the second cell430b. According to the example illustratedFIG. 6, the emission direction of light from each cell may be adjusted independently and controlled in various directions. For example, light may be transmitted to the right eye or left eye according to the light emission direction, which is determined according to the position of a turned-ON light source in each of the cells in relation to the pin hole425. In other words, light emitted from each cell may be transmitted in a desired direction by selectively operating the light sources based on the relative positions of the light sources with respect to the pin hole425. Therefore, a 3D image may be displayed with images provided into the left and right eyes sequentially by adjusting the light emission directions from the cells. Furthermore, in the backlight unit400, two or more light sources may be simultaneously turned ON in the light source array415in each of the cells, according to desired operation.

According to the example illustrated inFIG. 6, a 2D image may be displayed by turning ON the light sources in the cells in such a manner that the turned ON light sources are each in substantially the same position. Therefore, a display having the backlight unit400may be convert an image from a 2D image to 3D image by adjusting the position of the turn-ON light sources arranged in the light source array415. According to the above example, an entire area of the display panel may be used to display either the left-eye image or the right-eye image, and thus a 3D image may be displayed without reducing the resolution of the observed image.

According to the above examples, an emission unit of the backlight unit adjusts a light emission direction of each of a plurality of cells to form a 3D image. For example, the backlight unit300illustrated inFIG. 5includes a plurality of cells325a,325b, and325c. A light emission direction with respect to each shutter in each cell can be estimated based on an emission angle of the light passing through the shutter when it is opened. According to the estimated relationship between the light emission direction and the location of each shutter in the shutter array327, the emission unit may direct light from each cell in a left eye direction or in a right eye direction, thereby generating a 3D image. The method of adjusting light emission direction of each cell based on the estimated relationship between a light emission direction and a location of each shutter in the backlight unit300may be similarly applied in other backlight units100,200,200and400.

According to the examples described above, a display may display images of two or more views by increasing a refresh rate. A screen in one period may be referred to as one frame, and a scanning speed corresponding to a screen of each view included in one frame may be referred to as a refresh rate. For example, when a frequency for one frame is 60 Hz, four views for the frame may be provided with a refresh rate of 240 Hz or higher. A 3D image with four views may be displayed by adjusting the refresh rate while transmitting backlight into a desired light emission direction for each view (i.e. either for left eye or right eye) at a speed corresponding to the refresh rate. The number of views may be higher than four views, and thus a 3D image according to the embodiments of the present invention may also be displayed with a various number of views.

Further according to the above examples, if the number of views is greater than two views, two or more 3D images may be generated. For example, 3D images may be generated for two or more users, or a single user may view 3D images from various perspectives or angles. As an additional example, 3D images may be generated by various combinations of the images viewed by a right eye RE and a left eye LE. For example, an image viewed by a right eye RE may be combined with a variety of images viewed by left eye LE to generate various 3D images. As another example, if a first image viewed by a right eye RE is combined with a second image viewed by left eye LE to generate a first perspective or first angle of a 3D image, the second image may be viewed by right eye RE and combined with a third image viewed by left eye LE to generate a second perspective or second angle of the 3D image.

FIG. 7illustrates an example of operation of a backlight unit synchronized with a display panel. If the display panel is driven using a thin film transistor (TFT) in an active matrix (AM) or passive matrix (PM) method, all pixels of the display panel may not be capable of displaying a frame simultaneously, but instead display the frame in a scanning manner. Thus, a left-eye image and a right-eye image may be mixed and displayed together. If the light emission direction of the backlight unit is only either for the left-eye-image or for the right-eye image, cross-talk issues may arise. In order to reduce cross-talk, a light emission direction of the backlight unit may be adjusted in synchronization with scanning of the display panel. For example, when the T-th frame of the right-eye image as illustrated inFIG. 7is formed in an upper region of the display panel and the T-th frame of the left-eye image is formed in a lower region of the display panel, light emitted from a corresponding upper region of the backlight unit may be adjusted to be directed to the right eye, and light emitted from a corresponding lower region of the backlight unit may be adjusted to be directed to the left eye.

FIGS. 8A and 8Billustrate another example of operation of a backlight unit synchronized with a display panel. As illustrated inFIG. 8A, the display panel may be divided into a left region and a right region. At a first time t1, a left-eye image may be formed in the left region, and a right-eye image may be formed in the right region. The light emission direction of the backlight unit may be provided in such a way that light emitted from a left region of the backlight unit, corresponding to the left-eye image displayed on the left region of the display panel, may be directed into the left eye, and light emitted from a right region of the backlight unit, corresponding to the right-eye image display on the right region of the display panel, may be directed into the right eye. Thus, cross-talk caused by image mixing of the left-eye image and the right-eye image according to the scanning direction of the display panel may be reduced.

On the other hand, the right-eye image may be formed in the left region of the display panel as illustrated inFIG. 8B, and the left-eye image may be formed in the right region of the display panel. In this case, the light emission direction of the backlight unit may be adjusted to accommodate the position of the left-eye image and right-eye images on the display panel in such a way that light emitted from the left region of the backlight unit may be directed into the right eye to illuminate the right-eye image displayed on the left region of the display panel, and light emitted from the right region of the backlight unit may be directed into the left eye to illuminate the left-eye image displayed on the right region of the display panel. In this manner, the left-eye image and the right-eye image are switched their positions on the display panel, as compared to their positions inFIG. 8A, without reducing resolution.

According to the above examples, brightness and/or ON/OFF time ratio of the light sources in each of cells of the backlight unit may be adjusted in order to control the light emission directions of the divided regions (i.e. right region and left region) as shown inFIGS. 8A and 8B. For example, the backlight unit400ofFIG. 6may provide light in two different emission directions by adjusting the brightness of light sources in each cell430and/or the turn ON/OFF time ratio of the light source with respect to adjacent light sources arranged in the light source array415.

According to the above examples, the light emission direction of the backlight unit may be estimated based on an orientation of a display and/or positions of the viewer's eyes. As one example, the orientation of the display may be detected, and the light emission direction of the backlight may be adjusted based on the detected orientation information in order to change a display mode of the display. As another example, the light emission direction of the backlight may be adjusted based on the tracking information of positions of the viewer's eyes.

FIG. 9illustrates different light emission directions of the display at various orientations of the display. For example,FIG. 9illustrates patterns corresponding to opening/closing signals of the shutter array327of the backlight unit300illustrated inFIG. 5. The position of the display may be detected using a gravity (G) sensor, for example. The G sensor may detect the direction of the gravity on the display, and thereby determine the position/orientation of the display. The display may include information regarding a screen display direction according to the position of the display. When a position change of the display is detected by the G sensor, the display recognizes the screen display direction corresponding to the new orientation of the display. The backlight unit may adjust the light emission direction with the recognized new screen display direction, and thereby conversion of the display mode may occur.

FIG. 10illustrates procedures for adjusting a light emission direction based on tracking information of a user's eyes. First, the positions of the eyes of the viewer are determined, and the center position of each of the cells in the backlight unit is checked. For example, the positions of the eyes of the viewer may be determined using a camera directed towards the user. A light emission angle of each of the cells is calculated according to the position of the left eye XL, YL, ZLand the position of the right eye XR, YR, ZR. A control signal is sent to the backlight unit to control an emission unit of each of the cells. For example, the control signal may turn ON/OFF light sources of each of the cells, may open/close shutters in a shutter array, or may change the level of voltage supplied to each of the cells.

A left-eye image and a right-eye image are formed according to image data. The image data may include data such as color data RGB and depth data D. The image data may include 3D image data as well as 2D image data. Here, a 3D image will be described. A display control signal is transmitted to a display panel according to left-eye image data and right-eye image data, thereby forming the left-eye image and the right-eye image. The left-eye image and the right-eye image may be formed simultaneously or sequentially. For the left-eye image, the emission unit of the backlight unit may provide light to be directed toward the left eye. For the right-eye image, the emission unit of the backlight unit allows light to be directed toward the right eye, and thereby a 3D image is formed when both the left-eye image and the right-eye image are viewed.

In addition to the automatic eye tracking, a user may designate the light emission direction by arbitrarily selecting an emission mode. For example, when the available emission modes include a front emission mode, a left emission mode, and a right emission mode, the user may select the front emission mode in which the view of the images on the display may be restricted to the user only and not visible to other people.

While certain examples have been described above, it should be apparent that modifications and variations thereto are possible, all of which fall within the spirit and scope of the invention. With respect to the above descriptions, it should be recognized that the optimum relationships for the components and steps of the invention, including variations in order, form, content, function and manner of operation, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. The above description and drawings are illustrative of modifications that can be made without departing from the present invention, the scope of which is to be limited only by the following claims.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will be apparent to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalent are intended to fall within the scope of the invention as claimed.