KR20130039972A - The backlight unit and the display device having the same - Google Patents

Abstract

The embodiment provides a light unit including a light emitting module, a light guide plate that receives light from the light emitting module side by side, and emits the light to an upper surface thereof, and a phosphor structure formed on or below the light guide plate to convert wavelengths of emitted light of the light guide plate. . Therefore, manufacturing is simple by forming a phosphor dot on the upper or lower portion of the light guide plate without including the phosphor inside the package. In addition, the chromatic aberration of light can be precisely controlled by modifying the wavelength of the final light emitted from the light guide plate.

Description

BACKLIGHT UNIT AND THE DISPLAY DEVICE CONTAINING THE SAME {THE BACKLIGHT UNIT AND THE DISPLAY DEVICE HAVING THE SAME}

The present invention relates to a backlight unit and a display device including the same. In particular, the present invention relates to a display device in which a light emitting diode is formed as a backlight unit.

A light emitting diode (LED) may form a light emitting source using compound semiconductor materials such as GaAs series, AlGaAs series, GaN series, InGaN series, and InGaAlP series.

Such a light emitting diode is packaged and used as a light emitting device that emits a variety of colors, and the light emitting device is used as a light source in various fields such as a lighting indicator for displaying a color, a character display, and an image display.

The embodiment provides a backlight unit having a new structure and a display device including the same.

The embodiment provides a backlight unit including a light emitting module having a new structure.

The embodiment provides a light unit including a light emitting module, a light guide plate that receives light from the light emitting module side by side, and emits the light to an upper surface thereof, and a phosphor structure formed on or below the light guide plate to convert wavelengths of emitted light of the light guide plate. .

According to the present invention, manufacturing is simple by forming a phosphor structure on the upper or lower portion of the light guide plate without including the phosphor inside the package. In addition, the chromatic aberration of light can be precisely controlled by modifying the wavelength of the final light emitted from the light guide plate.

1 is an exploded perspective view of a display device according to a first exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II ′ of the display device of FIG. 1.
3 is a view illustrating the light emitting module of FIG. 1.
4 is a perspective view illustrating another embodiment of the light guide plate of FIG. 3.
5 is a cross-sectional view illustrating an embodiment of the light emitting device package of FIG. 3.
6 is a cross-sectional view illustrating an embodiment of the light emitting device of FIG. 5.
7 is a cross-sectional view of a display device according to a second exemplary embodiment of the present invention.
8 is a cross-sectional view of a display device according to a third exemplary embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

In order to clearly illustrate the present invention in the drawings, thicknesses are enlarged in order to clearly illustrate various layers and regions, and parts not related to the description are omitted, and like parts are denoted by similar reference numerals throughout the specification .

In the description of an embodiment, each layer (film), region, pattern, or structure is formed “on” or “under” a substrate, each layer (film), region, pad, or pattern. In the case where it is described as "to", "on" and "under" include both "directly" or "indirectly" formed. Also, the criteria for top, bottom, or bottom of each layer will be described with reference to the drawings. The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. In addition, the size of each component does not necessarily reflect the actual size.

Hereinafter, a display device according to a first exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 6.

1 is an exploded perspective view of a display device according to a first exemplary embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II ′ of the display device of FIG. 1, and FIG. 3 is a view illustrating the light emitting module of FIG. 1. 4 is a perspective view illustrating another embodiment of the light guide plate of FIG. 3.

The display device according to the first embodiment includes a backlight unit and a display panel that receives light from the backlight unit and displays an image. Therefore, the backlight unit will also be described below by describing the display device.

1 to 4, the display device according to the first embodiment includes a bottom frame 10, a light emitting module 20 formed in the bottom frame 10, a reflective sheet 25, and a light guide plate 30. do.

The display device includes a light guide plate 30 formed on the light emitting module 20, the reflective sheet 25, and the reflective sheet 25 to form a light emitting unit, and the optical sheet 40 and the optical sheet 40 on the light guide plate 30. The top frame 70 is formed on the display panel 60 and the display panel 60.

The bottom frame 10 includes two bottom sides facing each other and a bottom surface having a rectangular planar shape having two short sides perpendicular to the long sides and two short sides facing each other and four sides extending vertically from the bottom surface.

The bottom frame 10 is coupled to the support member 50 formed on the optical sheet 40 to form the light emitting module 20, the reflective sheet 25, the light guide plate 30, and the optical sheet 40 in the bottom frame 10. ) Is stored.

The bottom frame 10 may be formed of, for example, a metal material, and a plurality of convex portions (not shown) may be formed on the bottom surface to enhance rigidity.

The reflective sheet 25 is formed on the bottom surface of the bottom frame 10.

On the other hand, the reflecting sheet 25 is composed of a reflecting material, a reflecting metal plate, and the like and reflects light leaked from the light guide plate 30 again.

The display device includes a light guide plate 30 that diffuses and reflects light emitted from the light emitting module 20 onto the plurality of light emitting modules 20 and the plurality of reflective sheets 25 and irradiates the display panel 60 with a surface light source. It is.

The light guide plate 30 is formed in a one-body shape corresponding to one screen defined by the display panel 60.

The integrated light guide plate 30 includes an upper surface and a lower surface, and the upper surface on which the surface light source is generated is flat.

The light guide plate 30 may be made of a PC material or a poly methy methacrylate (PMMA) material.

A plurality of protrusions 35 are formed on the upper surface of the light guide plate 30.

The protrusion 35 may be a phosphor ball in which the phosphor 35b is mixed in the translucent resin 35a as shown in FIG. 3.

The translucent resin 35a may be a polymer resin including silica, epoxy, or the like, and the phosphor 35b may include a mixture of phosphors 35b for emitting light having different wavelengths.

In this case, the plurality of protrusions 35 may be formed such that the content of the phosphor 35b increases as the distance from the light emitting module 20 increases.

That is, in order to compensate that the amount of light decreases as it moves away from the light emitting module 20, the uniformity of light with respect to the entire light guide plate 30 is secured by increasing the amount of the phosphor 35b.

In addition, in order to compensate for chromatic aberration generated while moving away from the light emitting module 20, the type of the phosphor 35b included in the protrusion 35 may be controlled.

Meanwhile, as shown in FIG. 4, while maintaining the content of the phosphor 35b in the protrusion 35 uniformly, the same effect as FIG. 3 may be realized by increasing the density of the protrusion 35 as the distance from the light emitting module 20 increases. have.

In FIGS. 3 and 4, the protrusion 35 has a hemispherical shape, but the cross section of the protrusion 35 has a semicircle, but is not limited thereto.

The light guide plate 30 may have a polygonal shape to correspond to one screen, and may have a rectangular shape, preferably a rectangular shape, according to the shape of the screen.

The light emitting module 20 is disposed on one side of the light guide plate 30.

The light emitting module may be a rectangular bar type as shown in FIG. 1.

2 to 3, the light emitting module 20 includes a plurality of light emitting chips 23 formed on the substrate 21.

The substrate 21 is a module substrate 21 having a pattern for driving the light emitting chip 23, and may be a metal substrate, a flexible substrate, or the like.

The substrate 21 is disposed in parallel with the side surface of the light guide plate 30, and a light emitting device package 23 is disposed between the substrate 21 and the light guide plate 30.

A plurality of light emitting device packages 23 are disposed on the module substrate 21.

The light emitting device package 23 emits light toward the side of the light guide plate 30 in a top view type that emits light to an upper surface of the module substrate 21.

 A pad for electrical connection with the light emitting device package 23 is formed on the substrate 21.

The light emitting device package 23 formed on the substrate 21 may include, for example, a light emitting diode (LED), but is not limited thereto.

Hereinafter, a light emitting device package applied to the present embodiment will be described with reference to FIGS. 5 and 6.

Referring to FIG. 5, the light emitting device package 23 is disposed on the body 210, at least one light emitting device 250 disposed on the body 210, and on the body 210. The first lead frame 230 and the second lead frame 240 are electrically connected to the device 250.

In addition, the light emitting device package 23 includes a resin material 260 to protect the light emitting device 250.

The resin material 260 is formed of a light transmitting resin and does not include a phosphor.

The body 210 may include at least one of a resin material such as polyphthalamide (PPA), silicon (Si), a metal material, photo sensitive glass (PSG), sapphire (Al ₂ O ₃ ), and a printed circuit board (PCB). It can be formed as one.

The body 210 may be formed of a conductive material. When the body 210 is a material having electrical conductivity, an insulating film (not shown) is formed on the surface of the body 210 so that the body 210 is electrically shorted with the first lead frame and the second lead frame. Can be configured to prevent. The circumferential shape of the body 210 viewed from above may have various shapes such as triangle, rectangle, polygon, and circle depending on the use and design of the light emitting device package 23.

The body 210 may be formed with a cavity 215 so that the upper portion is opened. The cavity 215 may be formed by, for example, injection molding, or may be formed by etching.

The cavity 215 may be formed in a cup shape, a concave container shape, or the like, and an inner side surface thereof may be a vertical side surface or an inclined side surface with respect to the bottom surface. When the inclined side is formed by performing wet etching on the body 210, the inclined side may have a slope of 50 ° to 60 °.

The first lead frame 230 and the second lead frame 240 may be formed on the body 210. The first lead frame 230 and the second lead frame 240 may provide power to the light emitting device 250.

Meanwhile, the first and second lead frames 230 and 240 are spaced apart from each other in the cavity 215, and have pads exposed to the bottom surface of the body 210 to protrude outward as shown in FIG. 2.

The light emitting device 250 may be mounted on the body 210. When the body 210 includes the cavity 215, the light emitting device 250 may be mounted in the cavity 215.

The light emitting device 250 may be directly mounted on the body 210 or may be electrically bonded to the first or second lead frames 230 and 240.

The light emitting device 250 may be mounted by using a wire bonding, die bonding, or flip bonding method, and the bonding method may be changed according to the chip type and the lead frame position of the chip.

 The light emitting device 250 may selectively include a semiconductor light emitting device manufactured using a compound semiconductor of Group III and Group V elements, such as AlInGaN, InGaN, GaN, GaAs, InGaP, AllnGaP, InP, InGaAs, and the like. have.

Referring to FIG. 6, the light emitting device 250 includes a substrate 251, a first conductive semiconductor layer 253, an active layer 255, a second conductive semiconductor layer 257, and an electrode layer 259.

The substrate 251 may be a light transmissive, insulating or conductive substrate, for example, sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP, Ge, Ga ₂ O ₃ , LiGaO ₃ At least one of may be used. A plurality of protrusions may be formed on an upper surface of the substrate 251, and the plurality of protrusions may be formed by etching the substrate 251 or may be formed of a light extraction structure such as a separate roughness. The protrusion may include a stripe shape, a hemispherical shape, or a dome shape. The thickness of the substrate 251 may be formed in the range of 30㎛ ~ 300㎛, but is not limited thereto.

A buffer layer (not shown) is formed on the substrate 251, and the buffer layer may be formed of at least one layer using a group 2 to 6 compound semiconductor. The buffer layer includes a semiconductor layer using a group III-V compound semiconductor, for example, In _x Al _y Ga _{1 -xy} N (0 = x = 1, 0 = y = 1, 0 = x + y = 1) As a semiconductor having a compositional formula of, at least one of compound semiconductors such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN and the like. The buffer layer may be formed in a super lattice structure by alternately arranging different semiconductor layers.

The buffer layer may be formed to mitigate the difference in lattice constant between the substrate 251 and the nitride-based semiconductor layer, and may be defined as a defect control layer. The buffer layer may have a value between a lattice constant between the substrate 251 and the nitride-based semiconductor layer.

The first conductive semiconductor layer 253 may be formed on the buffer layer. The first conductive semiconductor layer 253 is implemented as a group III -5 V compound semiconductor with a first conductivity type dopant doped, for example, _{n x Al y Ga 1 -x- y} N (0 = x = 1, 0 = y = 1, 0 = x + y = 1). When the first conductive semiconductor layer 253 is an N-type semiconductor layer, the dopant of the first conductive type is an N-type dopant and includes Si, Ge, Sn, Se, and Te.

A semiconductor layer may be formed between the buffer layer and the first conductive semiconductor layer 253, and the semiconductor layer may have a superlattice structure in which different first and second layers are alternately arranged. The thickness of the first layer and the second layer can be formed in several kPa or more.

A first conductive cladding layer (not shown) may be formed between the first conductive semiconductor layer 253 and the active layer 255. The first conductive clad layer may be formed of a GaN-based semiconductor, and the band gap may be formed to be greater than or equal to the band gap of the barrier layer of the active layer 255. The first conductive clad layer serves to constrain the carrier.

An active layer 255 is formed on the first conductive semiconductor layer 253. The active layer 255 may be formed of at least one of a double junction, a single quantum well, a multi quantum well (MQW), a quantum line, and a quantum dot structure. The active layer 255 has a well / barrier layer alternately disposed, and the period of the well layer / barrier layer is 2 using a stacked structure of InGaN / GaN, AlGaN / GaN, InGaN / AlGaN, InGaN / InGaN. It may be formed in ~ 30 cycles.

A second conductive cladding layer is formed on the active layer 255, and the second conductive cladding layer has a higher band gap than the band gap of the barrier layer of the active layer 255, and a group III-V compound semiconductor. For example, it may be formed of a GaN-based semiconductor.

A second conductive semiconductor layer 257 is formed on the second conductive cladding layer, and the second conductive semiconductor layer 257 includes a dopant of a second conductive type. The second conductive semiconductor layer 257 may be formed of any one of compound semiconductors such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, and the like. When the second conductive semiconductor layer 257 is a P-type semiconductor layer, the second conductive dopant may be a P-type dopant and may include Mg, Zn, Ca, Sr, and Ba.

In the light emitting structure, the conductive type of the first conductive type and the second conductive type may be formed to be opposite to the structure described above. For example, the second conductive type semiconductor layer 257 may be an N type semiconductor layer and the first type. The conductive semiconductor layer 253 may be implemented as a P-type semiconductor layer. In addition, an N-type semiconductor layer, which is a third conductive semiconductor layer having a polarity opposite to that of the second conductive type, may be further formed on the second conductive semiconductor layer 257. The light emitting device 250 may define the first conductive semiconductor layer 253, the active layer 255, and the second conductive semiconductor layer 257 as the light emitting structure 220, and the light emitting structure 220. May be implemented as any one of an NP junction structure, a PN junction structure, an NPN junction structure, and a PNP junction structure. The N-P and P-N junctions have an active layer disposed between the two layers, and the N-P-N junction or P-N-P junction includes at least one active layer between the three layers.

A first electrode pad is formed on the first conductive semiconductor layer 253, and an electrode layer 259 and a second electrode pad are formed on the second conductive semiconductor layer 257.

The electrode layer 259 is a current diffusion layer and may be formed of a material having transparency and electrical conductivity. The electrode layer 259 may be formed to have a refractive index lower than that of the compound semiconductor layer.

The electrode layer 259 is formed on an upper surface of the second conductive semiconductor layer 257, and the material may be indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), or indium aluminum zinc oxide (IGZO), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), ZnO, IrOx, RuOx, NiO, etc. It may be selected from, and may be formed of at least one layer. As another example, the electrode layer 259 may be formed as a reflective electrode layer, and the material may be selectively formed among metal materials such as, for example, Al, Ag, Pd, Rh, Pt, and Ir.

The first electrode pad and the second electrode pad are conductive materials and include Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co, Ni, Si, Ge, Ag, Au, and their It can be chosen from the optional alloys.

An insulating layer may be further formed on the surface of the light emitting device 250, and the insulating layer may prevent an interlayer short of the light emitting device and prevent moisture penetration.

The light emitting device package 23 does not include a phosphor for converting the light emitted from the light emitting device 250 in the package, and transmits the light emitted from the light emitting device 250 to the light guide plate 30 as it is.

Therefore, the emission light of the light emitting device 250 is emitted to the upper surface of the light guide plate 30 without wavelength conversion, and at this time, part of the light is caused by the phosphor 35b included in the projection 35 of the light guide plate 30. Wavelength is converted.

Therefore, precise chromatic aberration control is possible by measuring chromatic aberration of the output light of the light guide plate 30 and forming the phosphor 35b for the optimized color conversion into a projection.

The light emitting device package 23 may be electrically connected to the pad by a wire method or flip chip bonding.

The plurality of light emitting device packages 23 may be arranged in a row direction on the substrate 21, and the number and spacing of the light emitting device packages 23 may correspond to the amount of LED luminous flux, the direction angle, and the light emitting device package 23. It may change according to the interval. For example, the number of the light emitting device packages 23 may be reduced when the optical power of the LED is large.

On the other hand, the optical sheet 40 is disposed on the light guide plate 30.

For example, the optical sheet 40 may include a first diffusion sheet 41, a prism sheet 42, and a second diffusion sheet 43. The diffusion sheets 41 and 43 diffuse light emitted from the light guide plate 30, and the diffused light is collected by the prism sheet 42 into the light emitting region EA. Here, the prism sheet 42 may be selectively configured using a horizontal or / and vertical prism sheet, one or more brightness enhancing films, or the like.

The optical sheet 40 may not be formed, and only one diffusion sheet 41 or 43 may be formed, or only one prism sheet 42 may be formed. The number and type of the optical sheets 40 can be variously selected according to the required luminance characteristics.

 The support member 50 is formed on the optical sheet 40.

The support member 50 is coupled to the bottom frame 10 so that the reflective sheet 25, the light emitting module, the light guide plate 30, and the optical sheet 40 may be closely attached to the bottom frame 10, and may be coupled to the bottom frame 10. The display panel 60 is supported.

The support member 50 may be formed of a synthetic resin material or a metal material, for example.

The display panel 60 is disposed on the supporting member 50.

The display panel 60 displays image information by light irradiated from the light guide plate 30. For example, the display panel 60 may be implemented as a liquid crystal display panel. The display panel 60 may include an upper substrate, a lower substrate, and a liquid crystal layer interposed between the two substrates, and may further include polarizing sheets adhered to the upper surface of the upper substrate and the lower surface of the lower substrate, respectively.

The top frame 70 is formed on the display panel 60.

The top frame 70 includes a front part disposed on the front of the display device and a side part bent in a vertical direction from the front part and disposed on the side of the display device, and the side part includes the support member 50 and a screw (not shown). It can be coupled via a coupling member such as.

Hereinafter, a backlight unit according to another exemplary embodiment of the present invention will be described with reference to FIGS. 7 and 8.

Referring to FIG. 7, the backlight unit and the display device 200 including the same according to the second exemplary embodiment of the present invention are the same as those of the first exemplary embodiment described above except for the light guide plate.

Therefore, the description of the configuration except for the light guide plate is omitted.

A plurality of grooves 31a are formed on the upper surface of the light guide plate 30 of FIG. 7.

The groove 31a may have a hemispherical shape and a cross section may have an arc.

The groove 31a may be distributed over the entire upper surface of the light guide plate 30 as in the projection of FIG. 3. Formed.

The light-transmissive resin may be a polymer resin including silica, epoxy, and the like, and the phosphor may be a mixture of phosphors emitting light of different wavelengths.

In this case, the plurality of grooves 31a may be formed such that the content of the phosphor 36 increases as the distance from the light emitting module 20 increases.

That is, in order to compensate that the amount of light decreases as it moves away from the light emitting module 20, the uniformity of light with respect to the entire light guide plate is secured by increasing the amount of the phosphor.

In addition, in order to compensate for chromatic aberration caused by moving away from the light emitting module 20, the type of phosphor included in the groove 31a may be controlled.

On the other hand, as shown in Figure 4, while maintaining the content of the phosphor in the groove (31a) uniformly, the same effect can be realized by increasing the density of the groove (31a) as far away from the light emitting module.

In addition, the plurality of grooves 31a and the phosphor balls 36 may be formed on the bottom surface of the light guide plate 30 as shown in FIG. 8.

When the phosphor ball 36 is formed on the lower surface of the light guide plate 30 as shown in FIG. 8, light reflected from the reflective layer 25 formed under the light guide plate 30 and light emitted through the lower surface of the light guide plate 30 are formed. The phosphor ball 36 can be output by converting the wavelength.

Although the embodiments of the present invention have been described above in detail, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the range.

10: bottom frame,
20: light emitting module
25: reflective sheet,
30: light guide plate,
40: optical sheet,
50: support member,
60: display panel,
70: top frame

Claims (12)

Light emitting module,
A light guide plate which receives light from the light emitting module to a side and emits the light to an upper surface;
A phosphor structure formed on at least one of the upper and lower portions of the light guide plate to convert wavelengths of emitted light of the light guide plate;
Light unit comprising a. The method of claim 1,
The light-
A light unit comprising a module substrate and a plurality of light emitting device packages disposed on the module substrate. The method of claim 2,
The module substrate has a bar shape, and the plurality of light emitting device packages are arranged in a row direction on the module substrate. The method of claim 3,
The light emitting device package
Body Part,
First and second electrodes disposed separately in the body,
A light emitting device electrically connected to the first and second electrodes, and
Resin material covering the light emitting element
Including;
The light emitting device package is a light unit for transmitting the generated light of the light emitting device to the side of the light guide plate. 5. The method of claim 4,
The resin material does not contain a phosphor. The method of claim 1,
The phosphor structure is a light unit formed in a projection shape on the upper or lower surface of the light guide plate. The method of claim 1,
The phosphor structure is a light unit is formed in the groove formed on the upper or lower surface of the light guide plate. 8. The method according to claim 6 or 7,
The phosphor unit is higher in the phosphor content as the distance from the light emitting module. 8. The method according to claim 6 or 7,
The phosphor structure is higher in density as the distance from the light emitting module. 8. The method according to claim 6 or 7,
The phosphor structure includes at least two phosphors. 8. The method according to claim 6 or 7,
The phosphor structure includes a light unit different from the neighboring phosphor structure. The light unit of any one of claims 1 to 11; And
A display panel disposed on the light unit
Display device comprising a.

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