Patent Description:
Recently, there is increasing demand for making a display apparatus as thin as possible. Accordingly, for a liquid crystal display (LCD), an edge type backlight unit including a light source disposed at one side thereof is generally used.

However, a liquid crystal display including such an edge type backlight unit cannot realize high dynamic range (HDR) imaging, which is a method of producing images on a display screen so as to allow a viewer to experience a sense of viewing an actual scene through the images. In order to realize HDR, it is necessary to realize a difference in luminance of light emitted through the display apparatus depending upon locations on a display screen. However, the liquid crystal display employing the edge type backlight unit cannot realize a difference in luminance of light depending upon locations on the display screen.

Accordingly, various studies have been made to realize HDR through implementation of an active matrix type using a direct type backlight unit. One example of these studies is disclosed in <CIT> (<NUM>. <NUM>, hereinafter "Prior Document"). However, this publication discloses a display apparatus using a direct type backlight unit and a lens disposed to spread light emitted from a light emitting diode in a lateral direction. However, use of the lens provides a limitation in reduction in thickness of the display apparatus due to the thickness of the lens. The <CIT> discloses a backlight apparatus comprising a frame, an LED package mounted on the frame, a reflector covering the LED package, and an optical sheet, the LED package is covered by a molded lens. The <CIT> discloses an LED chip comprising a reflective layer. The <CIT> discloses a backlight device with a plurality of LED light sources covered by a resin layer, and reflective patterns on top of the resin layer in the area of the LED light sources. The <CIT> discloses a back light module for displays wherein separate lenses are provided for individual LEDs, the lenses havie concave portions, under which the LEDs are placed, and reflective patterns are provided to the lenses. The <CIT> discloses a lens for a back light unit with a concave portion receiving an LED, and a reflective layer provided on a substrate under the lens. The <CIT> discloses a lens for a light emitting module, having a concave portion and an LED package placed under the concave portion. The <CIT> discloses a lens for a back light unit, having a concave portion receiving an LED.

Although a backlight unit employs a lens in order to realize uniform surface light throughout the backlight unit by allowing light emitted from the light emitting diode to spread in the lateral direction, it is difficult to improve uniformity of a surface light source even using the lens.

Exemplary embodiments of the present disclosure provide a display apparatus that can improve uniformity of a surface light source while employing a direct type backlight.

In accordance with one aspect of the present disclosure, a display apparatus includes: a frame; a plurality of light emitting diode packages regularly arranged on the frame; an optical part disposed above the plurality of light emitting diode packages and including a display panel and at least one of a phosphor sheet and an optical sheet; and a plurality of lenses disposed between the frame and the optical part to respectively cover each of the light emitting diode packages and spreading light emitted from the corresponding light emitting diode package, wherein each of the light emitting diode packages includes a light emitting diode chip; and a reflector disposed on an upper surface of the light emitting diode chip and reflecting at least part of light emitted from the light emitting diode chip.

Each lens includes a lower surface having a concave portion defining a light incident face through which light enters the lens; and an upper surface through which light exits the lens, and a light emitting diode package is disposed inside the concave portion of the lens.

The light incident face of the lens includes an upper end portion and a side surface extending from the upper end portion to an entrance of the concave portion, and the concave portion has a width gradually decreasing from the entrance thereof to the upper end portion.

The side surface may be an inclined surface having a constant inclination from the entrance of the concave portion to the upper end portion or a curved inclined surface having a gradually decreasing inclination from the entrance of the concave portion to the upper end portion.

The upper end portion may be a flat surface or a curved surface.

The reflector may include a distributed Bragg reflector. The reflector may have a transmittance of higher than <NUM>% to less than <NUM>% with respect to light emitted from the light emitting diode chip.

The light emitting diode package may further include a molding part disposed to cover upper and side surfaces of the light emitting diode chip and the reflector.

The molding part may include at least one of at least one type of phosphor and at least one type of light diffuser.

According to exemplary embodiments, as a backlight unit of a display apparatus, light emitting diode packages each having a reflector disposed on a light emitting diode chip are coupled to lenses, respectively, thereby improving uniformity of surface light with respect to light emitted from a plurality of light emitting diode packages.

Exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Only the embodiments of <FIG> are embodiments of the claimed invention.

<FIG> and <FIG> are a top view and a bottom view of a display apparatus according to a first exemplary embodiment of the present disclosure, which is not according to the claimed invention, respectively, and <FIG> and <FIG> are cross-sectional views of the display apparatus according to the first exemplary embodiment of the present disclosure.

A display apparatus <NUM> according to the first exemplary embodiment of the present disclosure includes light emitting diode packages <NUM>, a front cover <NUM>, a frame <NUM>, an optical part <NUM>, and a light guide plate <NUM>. Each of the light emitting diode packages <NUM> includes a light emitting diode chip <NUM>, a reflector <NUM>, and a molding part <NUM>, which will be described below.

The front cover <NUM> may cover part of side and upper surfaces of a display panel <NUM> of the optical part <NUM>. The front cover <NUM> may have a hollow center and the display panel <NUM> may be disposed at the center of the front cover <NUM> such that an image displayed on the display panel <NUM> can be viewed outside the display apparatus.

The frame <NUM> may support the display apparatus <NUM> and may be coupled to one side of the front cover <NUM>. The frame <NUM> may be formed of a synthetic resin or a metallic material such as Al alloys. The frame <NUM> may be separated a predetermined distance from the optical part <NUM>. The light emitting diode package <NUM> may be disposed on the frame <NUM> so as to face the optical part <NUM>. Here, a distance between the frame <NUM> and the optical part <NUM> may be an optical distance (OD) from the light emitting diode package 100to the optical part <NUM>. In this exemplary embodiment, the optical distance (OD) may be, for example, about <NUM> to <NUM>.

The frame <NUM> may be provided at an upper side thereof with a substrate <NUM>, to which the light emitting diode package <NUM> is electrically connected. The substrate <NUM> serves to allow power supply to the light emitting diode package <NUM> therethrough.

The optical part <NUM> is disposed above the frame <NUM>, and includes a phosphor sheet <NUM>, a diffusion plate <NUM>, an optical sheet <NUM> and the display panel <NUM>.

The phosphor sheet <NUM> serves to perform wavelength conversion of light emitted from the light emitting diode package <NUM>. The phosphor sheet <NUM> may contain at least one type of phosphor and may further include at least one type of quantum dot (QD). In this exemplary embodiment, the light emitting diode package <NUM> may emit blue light or UV light, and light emitted through the phosphor sheet <NUM> may be white light.

The diffusion plate <NUM> serves to diffuse light in an upward direction upon receiving the light from the light emitting diode package <NUM>.

The optical sheet <NUM> may be disposed on the diffusion plate <NUM> and the display panel <NUM> may be disposed on the optical sheet <NUM>. The optical sheet <NUM> may include a plurality of sheets having different functions. By way of example, the optical sheet <NUM> may include one or more prism sheets and diffusion sheets. The diffusion sheet can provide more uniform brightness by preventing light emitted through the diffusion plate <NUM> from being partially collected. The prism sheet can collect light emitted through the diffusion sheet to allow the light to enter the display panel <NUM> at a right angle.

The display panel <NUM> is disposed on an upper surface of the display apparatus <NUM> and displays an image. The display panel <NUM> includes a plurality of pixels and can output an image corresponding to a color, brightness and chroma of each pixel.

As shown in <FIG> and <FIG>, the light guide plate <NUM> is interposed between the frame <NUM> and the optical part <NUM>. The light guide plate <NUM> serves to allow uniform emission of light towards the optical part <NUM> upon receiving light. The thickness of the light guide plate <NUM> may be the same as an optical distance (OD), which is a distance between the frame <NUM> and the optical part <NUM>, or may be smaller than the OD. That is, the optical distance corresponding to the distance from light emitting diode package <NUM> to the optical part <NUM> may be determined depending upon the thickness of the light guide plate <NUM>. In addition, an air gap may be formed between the light guide plate <NUM> and the optical part <NUM>.

The light emitting diode package <NUM> is disposed on the frame <NUM> and the light guide plate <NUM> is disposed above the light emitting diode package <NUM>. Here, the light guide plate <NUM> has a lower surface directly contacting the frame <NUM> and may be formed with a light source groove h placed corresponding to a location of the light emitting diode package <NUM>. Accordingly, light emitted from the light emitting diode package <NUM> enters the light guide plate <NUM> through the light source groove h.

Referring to <FIG> and <FIG>, the light source groove h has a concave shape and the shape of the light source groove h can be modified as needed. This will be described below. The number of light source grooves h may correspond to the number of light emitting diode packages <NUM>.

Referring to <FIG>, the display apparatus <NUM> includes a plurality of light emitting diode packages <NUM> regularly arranged thereon. By way of example, the light emitting diode packages <NUM> may be arranged in a matrix to be separated at constant intervals from each other.

<FIG> shows the structure wherein a plurality of light emitting diode packages <NUM> is regularly arranged. The display apparatus <NUM> can provide higher quality of HDR (high dynamic range) with increasing number of light emitting diode packages <NUM>.

In addition, the display apparatus may be provided with a plurality of power supply units <NUM>, which supply electric power to the plurality of light emitting diode packages <NUM>. Each power supply unit <NUM> can supply power to at least one light emitting diode package <NUM>. In this exemplary embodiment, electric power is supplied to <NUM> light emitting diode packages <NUM> through one power supply unit <NUM>. Upon receiving electric power from the power supply unit <NUM>, the plurality of light emitting diode packages <NUM> can emit light and be individually operated.

<FIG> is a sectional view of a light guide plate of the display apparatus according to the first exemplary embodiment of the present disclosure. The light guide plate <NUM> of the display apparatus <NUM> will be described in more detail with reference to <FIG>.

Referring to <FIG>, a plurality of light emitting diode packages <NUM> is disposed on the frame <NUM>, and a relationship between one of the light emitting diode packages <NUM> and the light guide plate <NUM> will be described together with the shape of the light guide plate <NUM>.

The light guide plate <NUM> is interposed between the frame <NUM> and the optical part <NUM> and has a predetermined area to be disposed over the entirety of the display apparatus <NUM>. The light guide plate <NUM> has a substantially flat upper surface and may have a roughness R on the upper surface thereof, as needed. The roughness R formed on the upper surface of the light guide plate <NUM> serves to diffuse light when the light is discharged through the light guide plate <NUM>. Thus, the roughness R may be formed in a predetermined pattern or may be formed in an irregular diffusion pattern. The irregular diffusion pattern may be formed through corrosion treatment with respect to the upper surface of the light guide plate <NUM>.

The light guide plate <NUM> is formed at a lower side thereof with the light source grooves h. The number of light source grooves h may correspond to the number of light emitting diode packages <NUM> and each of the light source grooves has a concave shape. The light source groove may be configured to diffuse light in a lateral direction of the light source groove h when the light enters the light source groove h. Thus, the depth of the light source groove h may be larger than the width thereof.

The light source groove h has a width gradually decreasing from a lower surface of the light guide plate <NUM> to an upper surface thereof and may have a concave upper surface, without being limited thereto. Alternatively, the light source groove h may have a flat upper surface. That is, the light source groove h may have a bell-shaped cross-section.

By way of example, the light guide plate <NUM> may have a thickness t1 of <NUM> to <NUM> and the light source groove h may have a depth t2 corresponding to about <NUM>% to about <NUM>% of the thickness of the light guide plate <NUM>. For example, when the light guide plate <NUM> has a thickness t1 of about <NUM>, the depth t2 of the light source groove h may be about <NUM>.

The roughness R may have a thickness t3 of <NUM> to <NUM>, for example, about <NUM>.

<FIG> is a graph comparing light emission through the light guide plate <NUM> when light is emitted from the light emitting diode packages according to the first exemplary embodiment of the present disclosure.

Referring to <FIG>, in order to confirm uniformity of light emitted from the light emitting diode package <NUM> due to use of the light guide plate <NUM> according to the first exemplary embodiment, images of light emitted from the light emitting diode packages <NUM> without passing through the light guide plate <NUM> are compared with images of light emitted from the light emitting diode packages <NUM> and passing through the light guide plate <NUM>. <FIG> shows images of light emitted from nine light emitting diode packages <NUM>, in which the OD is set to <NUM>.

Referring to a left image of <FIG>, which shows distribution of light emitted from the nine light emitting diode packages without passing through the light guide plate, it can be confirmed that the light emitted from the light emitting diode packages <NUM> is not spread and a spot is generated at each of the locations of the light emitting diode packages <NUM>.

Referring to a middle image of <FIG>, which shows distribution of light emitted from the nine light emitting diode packages and passing through the light guide plate <NUM> having a thickness of <NUM>, it can be confirmed that the light emitted from the light emitting diode packages <NUM> is more uniformly spread than the light shown in the left image and spots are partially generated at the locations of the light emitting diode packages <NUM>.

Referring to a right image of <FIG>, which shows distribution of light emitted from the nine light emitting diode packages and passing through the light guide plate <NUM> having a thickness of <NUM>, which is the same as the optical distance (OD), it can be confirmed that the light is more uniformly spread than the light shown in the left and middle images.

That is, when light emitted from the light emitting diode packages <NUM> is discharged through the light guide plate <NUM> as in this exemplary embodiment, the light guide plate <NUM> spreads the light around the light emitting diode packages <NUM>, whereby the light can be uniformly discharged through a light exit surface of the light guide plate <NUM>.

<FIG> is a sectional view of the light emitting diode package of the display apparatus according to the first exemplary embodiment of the present disclosure.

Referring to <FIG>, the light emitting diode package <NUM> according to the first exemplary embodiment of the present disclosure will be described in more detail. As shown in <FIG>, the light emitting diode package <NUM> includes a light emitting diode chip <NUM>, a reflector <NUM>, and a molding part <NUM>.

The light emitting diode chip <NUM> may include an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. Here, each of the n-type semiconductor layer, the active layer and the p-type semiconductor layer may include a Group III-V-based compound semiconductor. By way of example, each of the n-type semiconductor layer, the active layer and the p-type semiconductor layer may include a nitride semiconductor such as (Al, Ga, In)N.

The n-type semiconductor layer may be a conductive semiconductor layer containing n-type dopants (for example, Si) and the p-type semiconductor layer may be a conductive semiconductor layer containing p-type dopants (for example, Mg). The active layer is interposed between the n-type semiconductor layer and the p-type semiconductor layer, and may have a multi-quantum well (MQW) structure. The composition of the active layer may be determined so as to emit light having a desired peak wavelength.

In this exemplary embodiment, the light emitting diode chip <NUM> may be a flip-chip type light emitting diode chip <NUM>. In this structure, the light emitting diode chip <NUM> may be provided at a lower side thereof with an n-type electrode electrically connected to the n-type semiconductor layer and a p-type electrode electrically connected to the p-type semiconductor layer.

When light is emitted from the light emitting diode chip <NUM>, the light is emitted through upper and side surfaces of the light emitting diode chip <NUM>. In this exemplary embodiment, the light emitting diode chip <NUM> may have a size of, for example, <NUM> x <NUM> x <NUM> (length x width x thickness).

The reflector <NUM> may be disposed on the light emitting diode chip <NUM> so as to cover the entirety of an upper surface of the light emitting diode chip <NUM>. In this exemplary embodiment, the reflector <NUM> may reflect light emitted from the light emitting diode chip <NUM> or may allow some fractions of light emitted from the light emitting diode chip <NUM> to be transmitted therethrough while reflecting the remaining fraction of the light.

By way of example, the reflector <NUM> may include a distributed Bragg reflector (DBR). The distributed Bragg reflector may be formed by alternately stacking material layers having different indices of refraction. The distributed Bragg reflector can reflect the entirety or part of light emitted from the light emitting diode chip <NUM> depending upon the number of material layers constituting the distributed Bragg reflector. In addition, the reflector <NUM> may include a metal or other materials, instead of the distributed Bragg reflector, as needed. For example, the reflector <NUM> may have a light transmittance of <NUM>% to <NUM>%.

Here, the distributed Bragg reflector may be formed through molecular beam epitaxy, E-beam evaporation, ion-beam assisted deposition, reactive plasma deposition, or sputtering.

Referring to <FIG>, the molding part <NUM> may be disposed to cover the entirety of the light emitting diode chip <NUM>, on which the reflector <NUM> is disposed. That is, the molding part <NUM> may be disposed to cover the upper and side surfaces of the light emitting diode chip <NUM> excluding the n-type electrode and the p-type electrode disposed on the lower side of the light emitting diode chip <NUM>.

The molding part <NUM> may be formed of a transparent material, for example, silicone, so as to allow light emitted from the light emitting diode chip <NUM> to pass therethrough.

In this exemplary embodiment, the molding part <NUM> is formed to cover the light emitting diode chip <NUM> and may have a size of, for example, <NUM>,<NUM> x <NUM>,<NUM> x <NUM> (length x width x thickness). That is, the thickness of the molding part <NUM> may be larger than or the same as the sum of a thickness t of the light emitting diode chip <NUM> and a thickness d1 (hereinafter, first thickness) of the molding part <NUM> from the upper surface of the light emitting diode chip <NUM> to an upper surface of the molding part <NUM>. Here, the first thickness d1 of the molding part <NUM> may be smaller than or the same as the thickness t of the light emitting diode chip <NUM> (d1≤t).

In addition, a width d2 (hereinafter, first width) of the molding part <NUM> from a side surface of the light emitting diode chip <NUM> to a side surface of the molding part <NUM> may be smaller than the first thickness d1. In this exemplary embodiment, the first width d2 of the molding part <NUM> may be <NUM> times to <NUM> times, for example, about <NUM> times the first thickness d1.

In other words, the molding part <NUM> is formed such that the thickness d1 of the molding part <NUM> formed on the upper surface of the light emitting diode chip <NUM> is smaller than the width d2 of the molding part <NUM> formed on the side surface of the light emitting diode chip <NUM>. Light emitted from the light emitting diode chip <NUM> is blocked by the reflector disposed on the upper surface of the light emitting diode chip and can be mostly emitted in the lateral direction of the light emitting diode chip <NUM>. Furthermore, light emitted from the light emitting diode chip <NUM> is guided by the shape of the molding part <NUM> formed on the upper and side surfaces of the light emitting diode chip <NUM> to be more efficiently discharged in the lateral direction.

As such, since the light emitting diode package <NUM> including the molding part <NUM> formed to cover the light emitting diode chip <NUM> allows light emitted from the light emitting diode chip <NUM> to be discharged through the side surface thereof rather than the upper surface thereof, the light emitting diode package can be used as a light source for a backlight unit of the display apparatus <NUM>. Furthermore, when light is emitted from the light emitting diode package <NUM>, the light is refracted in the lateral direction while passing through the light guide plate <NUM>, thereby providing uniform light throughout the display panel <NUM> of the display apparatus <NUM>.

Particularly, since the light emitting diode package <NUM> allows light to be discharged in the lateral direction thereof, it is possible to omit a lens for diffusing light. In this exemplary embodiment, the light source groove h of the light guide plate <NUM> can act as a lens. In a direct type backlight unit, the lens serves to spread light in the lateral direction upon receiving light from the light emitting diode package <NUM>. According to this exemplary embodiment, since the light is spread in the lateral direction of the light emitting diode package <NUM> when the light enters the light guide plate <NUM> through the light source groove h of the light guide plate <NUM>, it is possible to omit a separate lens.

As such, since the display apparatus <NUM> according to this first exemplary embodiment does not employ a separate lens, it is possible to minimize the thickness of the display apparatus.

Further, the molding part <NUM> may be formed of a transparent material alone, or may further include at least one type of phosphor or at least one type of light diffuser for regulating light diffusion. In this exemplary embodiment, since the optical part <NUM> includes the phosphor sheet <NUM> as described above, the molding part <NUM> can omit a separate phosphor. Alternatively, in order to improve color reproduction of light emitted through the phosphor sheet <NUM> in the optical part <NUM>, the molding part <NUM> may contain at least one type of phosphor.

In this exemplary embodiment, the light emitting diode package <NUM> is illustrated as including the light emitting diode chip <NUM>, the reflector <NUM> and the molding part <NUM>. Alternatively, the molding part <NUM> may be omitted.

In an example not forming part of the invention, the light emitting diode package <NUM> may include the light emitting diode chip <NUM> alone such that the light emitting diode chip <NUM> is disposed in the light source groove h of the light guide plate <NUM>. With this structure, light emitted from the light emitting diode chip <NUM> can be spread in the lateral direction through the light guide plate <NUM>.

Alternatively, the light emitting diode package <NUM> may include the light emitting diode chip <NUM> and the reflector <NUM> without the molding part. With this structure, the reflector <NUM> can increase the amount of light discharged in the lateral direction by reflecting more light in the lateral direction than in the upward direction when the light is emitted from the light emitting diode chip <NUM>.

<FIG> is a graph comparing light emission from the light emitting diode package according to the first exemplary embodiment of the present disclosure.

<FIG> shows images and beam angles of light emitted from the light emitting diode package according to the first exemplary embodiment of the present disclosure. First, <FIG> shows far field data of images of light emitted from the light emitting diode chip <NUM> and photographed at an OD of <NUM>, at an OD of <NUM> and at an OD of <NUM>, respectively. <FIG> shows far field data of images of light emitted from the light emitting diode chip <NUM> with the reflector <NUM> disposed on the upper side thereof, and photographed at an OD of <NUM>, at an OD of <NUM> and at an OD of <NUM>, respectively. <FIG> shows far field data of images of light emitted from the light emitting diode chip <NUM> with the reflector <NUM> and the molding part <NUM> disposed thereon, and photographed at an OD of <NUM>, at an OD of <NUM> and at an OD of <NUM>, respectively.

It can be confirmed from the images and the far field data that the reflector <NUM> and the molding part <NUM> formed on the light emitting diode chip <NUM> allow uniform spreading of light emitted from the light emitting diode package <NUM>.

<FIG> is a sectional view of a light guide plate of a display apparatus according to a second exemplary embodiment of the present disclosure which is not according to the claimed invention.

A display apparatus <NUM> according to the second exemplary embodiment of the present disclosure includes a light emitting diode package <NUM>, a front cover <NUM>, a frame <NUM>, an optical part <NUM>, a light guide plate <NUM>, and a reflection sheet <NUM>. In description of the display apparatus <NUM> according to this exemplary embodiment, descriptions of the same components as those of the first exemplary embodiment will be omitted.

The following description will be given of features of the second exemplary embodiment, that is, the light guide plate <NUM> and the reflection sheet <NUM>, that are different from those of the first exemplary embodiment with reference to <FIG>.

The light guide plate <NUM> is interposed between the frame <NUM> and the optical part <NUM> and serves to achieve uniform emission of light towards an upper surface <NUM> of the light guide plate <NUM> by spreading light emitted from a plurality of light emitting diode packages <NUM> disposed on the frame <NUM> in the lateral direction. To this end, the light guide plate <NUM> is provided at a lower side thereof with light source grooves h each receiving the light emitting diode package <NUM>. As in the first exemplary embodiment, the number of light source grooves h may correspond to the number of light emitting diode packages <NUM> and each of the light sources h may have a concave shape. The concave shape of the light source groove is formed to spread light emitted from the light emitting diode package <NUM> to a plane direction of the light guide plate <NUM> and may have a bell shape, as shown in <FIG>, or other shapes as needed.

Although the depth and width of the light source groove h may be the same as those of the light source groove h of the light guide plate according to the first exemplary embodiment, the depth of the light source groove h according to this exemplary embodiment may be smaller than the depth of the light source groove according to the first exemplary embodiment. This structure results from the structure of the light guide plate having light exit grooves Eh formed above the light source grooves h.

Each of the light exit grooves Eh is formed above the light source groove h and the number of light exit grooves Eh corresponds to the number of light source grooves h. Referring to <FIG>, the light exit grooves Eh may have a conical shape and have a larger width than the light source grooves h. In addition, the width of the light exit groove Eh may be larger than the depth thereof.

Each of the light exit grooves Eh serves to reflect light on an inner surface thereof to spread in the lateral direction (plane direction) of the light guide plate <NUM> when the light emitted from the light emitting diode package <NUM> enters the light guide plate <NUM> through the light source groove h.

Accordingly, an inner tip (vertex of the conical shape) of the light exit groove (Eh) may have a gently curved surface instead of a sharp shape, or may have a flat surface as needed. In addition, although the light exit groove Eh is shown as having a linear inclined surface <NUM> in the cross-sectional view of <FIG>, the light exit groove Eh may have a concave inclined surface as shown in the inclined surface <NUM> of the light source groove h, or a convex inclined surface as needed.

The uppermost end of the light exit groove Eh extends to the upper surface <NUM> of the light guide plate <NUM>. The upper surface <NUM> of the light guide plate <NUM> may be a light exit surface through which the light exits the light guide plate <NUM>. In this exemplary embodiment, the upper surface <NUM> of the light guide plate <NUM> may be a substantially flat surface, without being limited thereto. Alternatively, the upper surface <NUM> of the light guide plate <NUM> may not be flat or may have a roughness as needed.

With the structure wherein the light guide plate has the light exit grooves Eh formed above light source grooves h as described above, light emitted from the light emitting diode package <NUM> is spread over the light guide plate <NUM> to be uniformly discharged through the upper surface <NUM> of the light guide plate <NUM>.

The reflection sheet <NUM> may be disposed on the lower surface of the light guide plate <NUM>. The reflection sheet <NUM> serves to increase the amount of light discharged through the upper surface of the light guide plate <NUM> when the light enters the light guide plate <NUM>.

The reflection sheet <NUM> may have a thickness of, for example, about <NUM> to <NUM>, which is similar to the thickness (for example, <NUM> to <NUM>) of the light emitting diode package <NUM>. Thus, the reflection sheet <NUM> may be separated from the light emitting diode package <NUM> by a predetermined distance or more in order to prevent light emitted from the light emitting diode package <NUM> from being lost through reflection by a side surface of the reflection sheet <NUM>.

Further, since the light emitting diode package <NUM> and the light guide plate <NUM> are disposed on a substrate <NUM> mounted on the frame <NUM> and the reflection sheet <NUM> is disposed on the lower surface of the light guide plate <NUM>, the lower surface of the light guide plate <NUM> has a step due to the thickness of the reflection sheet <NUM>. That is, the lower surface of the light guide plate <NUM> includes a first lower surface <NUM> and a second lower surface <NUM>, and the step is formed between the first lower surface <NUM> and the second lower surface <NUM>.

The first lower surface <NUM> may adjoin the substrate <NUM> on which the light emitting diode chip <NUM> is disposed, and the second lower surface <NUM> may adjoin the reflection sheet <NUM>. As such, the step is formed between the second lower surface <NUM> and the first lower surface <NUM> due to the thickness of the reflection sheet <NUM>.

Furthermore, the first lower surface <NUM> may extend from a distal end of the light source groove h and an inclined surface <NUM> may be formed between the first lower surface <NUM> and the second lower surface <NUM>. The inclined surface <NUM> serves to connect both ends of the step formed between the first lower surface <NUM> and the second lower surface <NUM>. With this structure, light entering the light guide plate through the light source groove h can be reflected by the inclined surface <NUM> towards the upper surface of the light guide plate <NUM>. Further, the structure of the light guide plate including the inclined surface <NUM> can prevent the light emitted from the light emitting diode chip <NUM> from directly reaching the side surface of the reflection sheet <NUM>, thereby minimizing loss of light through reflection by the side surface of the reflection sheet <NUM>.

In other configurations, the light guide plate may include the inclined surface <NUM> directly extending from the distal end of the light source groove h to the second lower surface <NUM> by omitting the first lower surface <NUM>, as needed.

As such, when light emitted from the light emitting diode chip <NUM> received in the light source groove h of the light guide plate <NUM> on the substrate <NUM> enters the light guide plate <NUM> through the light source groove h, the light can be discharged through the upper surface <NUM> of the light guide plate <NUM> while being reflected by some portions of the light guide plate <NUM> to spread in the lateral direction of the light guide plate <NUM>. Here, the light exit grooves Eh formed on the light guide plate <NUM> and placed corresponding to the light source groove h can improve efficiency of spreading light in the lateral direction of the light guide plate <NUM>.

Furthermore, the reflection sheet <NUM> disposed on the lower surface of the light guide plate <NUM> can increase the amount of light discharged through the upper surface <NUM> of the light guide plate <NUM>. In order to prevent loss of light emitted from the light emitting diode chip <NUM> due to reflection by the side surface of the reflection sheet, the light emitting diode chip <NUM> may be separated from the reflection sheet <NUM> by a predetermined distance or more. Furthermore, the light source groove h and the inclined surface <NUM> of the light guide plate <NUM> are disposed between the light emitting diode chip <NUM> and the reflection sheet <NUM> to prevent light emitted from the light emitting diode chip <NUM> from directly reaching the side surface of the reflection sheet <NUM>, thereby minimizing loss of light through reflection by the side surface of the reflection sheet <NUM>.

<FIG> shows simulation images of light emitted from the display apparatus according to the second exemplary embodiment of the present disclosure.

<FIG> shows simulation results as to uniformity of light discharged from the display apparatus <NUM> according to the second exemplary embodiment of the present disclosure, in which the light emitting diode packages <NUM> are disposed. For simulation, the light guide plate <NUM> and the reflection sheet <NUM> according to this exemplary embodiment were disposed on the light emitting diode packages <NUM>, and the light guide plate <NUM> was coved only by a brightness enhancement film (BEF) and a diffusion sheet. <FIG> shows only part of the display apparatus.

From the simulation results and the graphs in the x-axis and y-axis directions shown in <FIG>, it can be seen that the display apparatus generally had a light distribution of <NUM>. 56E+<NUM> or more and the light distribution had a substantially linear shape both in the x-axis direction and in the y-axis direction. Although only part of the display apparatus <NUM> is shown in <FIG>, it can be confirmed that the intensity of light was maintained at a certain level or higher and the light was generally uniformly discharged through the display apparatus.

Accordingly, it can be seen that light emitted from the light emitting diode packages <NUM> can be uniformly spread in the light guide plate <NUM> and thus can be uniformly discharged as surface light through the upper surface <NUM> of the light guide plate <NUM>, which is the light exit surface.

<FIG> are a top view and a bottom view of a display apparatus according to one exemplary embodiment of the claimed invention, respectively, and <FIG> are cross-sectional views of the display apparatus according to the exemplary embodiment of the claimed invention.

A display apparatus <NUM> according to one exemplary embodiment of the claimed invention includes light emitting diode packages <NUM>, a front cover <NUM>, a frame <NUM>, an optical part <NUM>, and lenses <NUM>. Each of the light emitting diode packages <NUM> includes a light emitting diode chip <NUM>, a reflector <NUM>, and a molding part <NUM>, which will be described below.

The frame <NUM> may support the display apparatus <NUM> and may be coupled at one side thereof to the front cover <NUM>. The frame <NUM> may be formed of a synthetic resin or a metallic material such as an Al alloy. The frame <NUM> may be separated a predetermined distance from the optical part <NUM>. The light emitting diode package <NUM> may be disposed on the frame <NUM> so as to face the optical part <NUM>. Here, a distance between the frame <NUM> and the optical part <NUM> may be an optical distance (OD) from the light emitting diode package <NUM> to the optical part <NUM>. In this exemplary embodiment, the optical distance (OD) may be, for example, about <NUM> to <NUM>.

The optical sheet <NUM> may be disposed on the diffusion plate <NUM> and the display panel <NUM> may be dispose on the optical sheet <NUM>. The optical sheet <NUM> may include a plurality of sheets having different functions. By way of example, the optical sheet <NUM> may include one or more prism sheets and diffusion sheets. The diffusion sheet can provide more uniform brightness by preventing light emitted through the diffusion plate <NUM> from being partially collected. The prism sheet can collect light emitted through the diffusion sheet to allow the light to enter the display panel <NUM> at a right angle.

Referring to <FIG>, each of the lenses <NUM> is disposed on the frame <NUM> between the frame <NUM> and the optical part <NUM>. The lens <NUM> serves to guide light emitted from the light emitting diode package <NUM> to travel in a lateral direction of the lens <NUM>. This structure will be described in detail with reference to <FIG>.

<FIG> is a sectional view of a lens of the display apparatus according to the exemplary embodiment of the claimed invention.

The lens <NUM> shown in <FIG> is provided for illustration only and the shape of the lens <NUM> can be modified, as needed.

An optical distance (OD) corresponding to a distance from the frame <NUM> to the optical part <NUM> can be adjusted depending upon the height of the lens <NUM>. The lens <NUM> is disposed on the frame <NUM> such that an upper surface <NUM> of the lens <NUM> closely adjoins the optical part <NUM>. Alternatively, an air gap may be formed between the upper surface <NUM> of the lens <NUM> and the optical part <NUM>. That is, the OD can be adjusted as needed.

Referring to <FIG>, in this exemplary embodiment, the lens <NUM> includes a lower surface <NUM>, an upper surface <NUM>, a flange <NUM>, and legs <NUM>. The lower surface <NUM> includes a concave portion <NUM> and an inclined surface surrounding the concave portion <NUM>. In some exemplary embodiments, a flat surface may be disposed between the concave portion <NUM> and the inclined surface, as needed.

The inclined surface serves to allow light emitted from the light emitting diode package <NUM> and entering the lens <NUM> to be discharged through a side surface of the lens <NUM> without total internal reflection, and an inclination of the inclined surface depends upon the shape of the lens <NUM>.

The concave portion <NUM> defines a light incident face <NUM> through which light emitted from the light emitting diode package <NUM> enters the lens <NUM>. That is, the light incident face <NUM> is an inner surface of the concave portion <NUM> and includes a side surface 330a and an upper end portion 330b. The concave portion <NUM> has a shape gradually decreasing in width from an entrance thereof in an upward direction. The side surface 330a may have a constant inclination from the entrance of the concave portion <NUM> to the upper end portion 330b. Alternatively, the side surface 330a may have an inclination gradually decreasing from the entrance of the concave portion <NUM> to the upper end portion 330b. That is, the side surface 330a may have a convex shape, as shown in <FIG>. Referring to <FIG>, the upper end portion 330b may include a concave surface or may have a flat surface, as needed.

Height of the concave portion <NUM> may be adjusted depending upon a beam angle of the light emitting diode package <NUM>, the shape of the upper surface <NUM> of the lens <NUM>, directional distribution of light, and the like.

The upper surface <NUM> of the lens <NUM> is configured to allow light having entered the lens <NUM> to spread in a wide directional distribution, and acts as a light exit surface through which light exits the lens <NUM>. By way of example, the upper surface <NUM> of the lens <NUM> may include a concave surface 350a near a central axis of the lens <NUM> and a convex surface 350b extending from the concave surface 350a. The concave surface 350a guides light traveling near the central axis of the lens <NUM> to be directed outwards, and the convex surface 350b increases the amount of light traveling outward from the central axis of the lens <NUM>.

The flange <NUM> connects the upper surface <NUM> to the lower surface <NUM> and defines the size of the lens <NUM>. A side surface of the flange <NUM> and the lower surface <NUM> may have a roughened pattern, as needed. The legs <NUM> of the lens <NUM> are coupled to the frame <NUM> to secure the lens <NUM>. By way of example, a leading end of each leg <NUM> may be bonded to the frame <NUM> by a bonding agent and the like.

The light emitting diode package <NUM> described below may be disposed on the frame <NUM> and the lens <NUM> may be disposed on the light emitting diode package <NUM>. Here, the lens <NUM> may be disposed on the frame <NUM> such that the light emitting diode package <NUM> is placed inside the concave portion <NUM>. With this structure, light emitted from the light emitting diode package <NUM> can enter the lens <NUM> through the light incident face <NUM> of the concave portion <NUM>.

In this exemplary embodiment, the number of lenses <NUM><NUM>. are the same as the number of light emitting diode packages <NUM>.

<FIG> shows the structure wherein a plurality of light emitting diode packages <NUM> is regularly arranged. The display apparatus <NUM> can provide higher quality HDR (high dynamic range) with increasing number of light emitting diode packages <NUM>.

<FIG> is a sectional view of a light emitting diode package according to one exemplary embodiment of the claimed invention.

Referring to <FIG>, a light emitting diode package <NUM> according to one exemplary embodiment of the claimed invention will be described in more detail. As shown in <FIG>, the light emitting diode package <NUM> includes a light emitting diode chip <NUM>, a reflector <NUM>, and a molding part <NUM>.

In this exemplary embodiment, the light emitting diode chip <NUM> may be a flip-chip type light emitting diode chip <NUM>. With this structure, the light emitting diode chip <NUM> may be provided at a lower side thereof with an n-type electrode electrically connected to the n-type semiconductor layer and a p-type electrode electrically connected to the p-type semiconductor layer. When light is emitted from the light emitting diode chip <NUM>, the light is emitted through upper and side surfaces of the light emitting diode chip <NUM>.

By way of example, the reflector <NUM> may include a distributed Bragg reflector (DBR). The distributed Bragg reflector may be formed by alternately stacking material layers having different indices of refraction. The distributed Bragg reflector can reflect the entirety or part of light emitted from the light emitting diode chip <NUM> depending upon the number of material layers constituting the distributed Bragg reflector. In addition, the reflector <NUM> may include a metal or other materials, instead of the distributed Bragg reflector, as needed. For example, the reflector <NUM> may have a light transmittance of higher than <NUM>% to less than <NUM>%, for example, higher than <NUM>% to <NUM>%.

In this exemplary embodiment, the molding part <NUM> may be formed of a transparent material alone, or may further include at least one type of phosphor or at least one type of light diffuser for regulating light diffusion. In this exemplary embodiment, since the optical part <NUM> includes the phosphor sheet <NUM> as described above, the molding part <NUM> can omit a separate phosphor. Alternatively, in order to improve color reproduction of light emitted through the phosphor sheet <NUM> in the optical part <NUM>, the molding part <NUM> may contain at least one type of phosphor.

In this exemplary embodiment, the light emitting diode package <NUM> is illustrated as including the light emitting diode chip <NUM>, the reflector <NUM> and the molding part <NUM>. Alternatively, at least one of the reflector <NUM> and the molding part <NUM> may be omitted.

In an example not forming part of the invention, the light emitting diode package <NUM> may include the light emitting diode chip <NUM> alone such that the light emitting diode chip <NUM> is disposed in the concave portion <NUM> of the lens <NUM>.

<FIG> shows an image of light emitted from a plurality of light emitting diode packages, explaining uniformity of light emitted from the display apparatus according to the exemplary embodiment of the claimed invention. <FIG> shows images and graphs comparing uniformity of light emitted from the display apparatus according to the exemplary embodiment of the claimed invention depending upon structure of light emitting diode packages and <FIG> shows graphs comparing directional characteristics of light emitted from the display apparatus according to the exemplary embodiment of the claimed invention depending upon structure of light emitting diode packages.

Next, uniformity and directional characteristics of light emitted through the light emitting diode package <NUM> and the lens <NUM> in the display apparatus <NUM> according to the exemplary embodiment will be described with reference to <FIG> and <FIG>. Referring to <FIG>, <NUM> light emitting diode packages <NUM> are coupled to <NUM> lenses <NUM>, respectively, and the optical distance OD is set to <NUM>.

<FIG> shows uniformity of light emitted from the display apparatus depending upon the structure of the light emitting diode packages <NUM>. The first image and graph show results measured using a structure wherein the light emitting diode chip <NUM> not including the reflector <NUM> is disposed in the concave portion <NUM> of the lens <NUM> and the optical part <NUM> including the diffusion sheet <NUM> and the phosphor sheet <NUM> is disposed above the lens <NUM>. The second image and graph show results measured using a structure wherein the light emitting diode package <NUM> including the reflector <NUM> having a reflectivity of <NUM>% and disposed on the light emitting diode chip <NUM> is disposed in the concave portion <NUM> of the lens <NUM> and the optical part <NUM> including the diffusion sheet <NUM> and the phosphor sheet <NUM> is disposed above the lens <NUM>. The third image and graph show results measured using a structure wherein the light emitting diode package <NUM> including the reflector <NUM> having a reflectivity of <NUM>% and disposed on the light emitting diode chip <NUM> is disposed in the concave portion <NUM> of the lens <NUM> and the optical part <NUM> including the diffusion sheet <NUM> and the phosphor sheet <NUM> is disposed above the lens <NUM>.

From the measurement results of uniformity obtained using the light emitting diode packages <NUM> including the different reflectors <NUM>, it could be seen that the light emitting diode package <NUM> including the reflector <NUM> having a reflectivity of <NUM>% provided a uniformity degree of <NUM>%, which was about <NUM>% higher than the light emitting diode package <NUM> not including the reflector <NUM>.

In addition, referring to <FIG>, from the measurement results of the directional characteristics of light, it could be seen that the light emitting diode package <NUM> including the reflector <NUM> having a reflectivity of <NUM>% exhibited better spreading of light in the lateral direction than the light emitting diode package <NUM> not including the reflector <NUM>. In addition, although the light emitting diode package <NUM> including the reflector <NUM> provided high light distribution efficiency, the light distribution efficiency of the light emitting diode package <NUM> could be further improved through the lens <NUM> coupled thereto.

Although certain exemplary embodiments have been described herein, it should be understood by those skilled in the art that these embodiments are given by way of illustration only, and that various modifications, variations, and alterations can be made without departing from the scope of the invention as defined by the accompanying claims.

Claim 1:
A display apparatus comprising:
a frame (<NUM>);
a plurality of light emitting diode packages (<NUM>) regularly arranged on the frame (<NUM>);
an optical part disposed above the plurality of light emitting diode packages (<NUM>) and comprising a display panel (<NUM>) and at least one of a phosphor sheet (<NUM>) and an optical sheet (<NUM>); and
a plurality of lenses (<NUM>) disposed between the frame (<NUM>) and the optical part to respectively <NUM>. cover each of the light emitting diode packages (<NUM>) and spreading light emitted from the corresponding light emitting diode package (<NUM>),
wherein each of the light emitting diode packages (<NUM>) comprises a light emitting diode chip (<NUM>); and a reflector (<NUM>) disposed on an upper surface of the light emitting diode chip (<NUM>) and reflecting at least part of light emitted from the light emitting diode chip (<NUM>); wherein each lens (<NUM>) comprises:
a lower surface (<NUM>) having a concave portion (<NUM>) defining a light incident face (<NUM>) through which light enters the lens (<NUM>); and an upper surface (<NUM>) through which light exits the lens (<NUM>), and
wherein a emitting diode package (<NUM>) is disposed inside the concave portion (<NUM>) of the lens (<NUM>); and
wherein the light incident face (<NUM>) of the lens (<NUM>) comprises an upper end portion and a side surface (330a) extending from the upper end portion to an entrance of the concave portion (<NUM>), and the concave portion (<NUM>) has a width gradually decreasing from the entrance thereof to the upper end portion.