KR20140028528A - Backlight unit - Google Patents

Abstract

A backlight unit according to the embodiment of the present invention includes: a light guide plate, a light source module which is arranged on at least one side of the light guide plate, and a heat radiation unit which includes a support unit which supports the light source module and a curved part which is integrally extended from the support unit. The curved part includes a plurality of first segments which are arranged in a first direction and a plurality of second segments which are arranged in a second direction which is different from the first direction. At least one among the width of the first segment, the width of the second segment closest to the light source module, the width of the second segment farthest from the light source module, and the width of the first segment connecting the adjacent second segments is determined to maximize heat radiation. [Reference numerals] (AA) Second direction; (BB) First direction

Description

BACKLIGHT UNIT [0001]

An embodiment relates to a backlight unit.

In general, typical large display devices include a liquid crystal display (LCD) or a plasma display panel (PDP).

Unlike the self-luminous PDP, the LCD requires a separate backlight unit due to the absence of its own light emitting device.

The backlight unit used in LCD is classified into an edge type backlight unit and a direct type backlight unit according to the position of the light source. In the edge type, the light source is disposed on the left and right sides or the top and bottom sides of the LCD panel and the light guide plate is used. Since the light is evenly distributed on the front surface, the light is uniform and the panel thickness can be made ultra thin.

The direct method is a technology generally used for a display of 20 inches or more. Since a plurality of light sources are disposed under the panel, it has an advantage of superior light efficiency compared to an edge method, and thus is mainly used for a large display requiring high brightness.

Cold Cathode Fluorescent Lamp (CCFL) was used as the light source of the existing edge type or direct type backlight unit. However, the CCFL-based backlight unit consumes a considerable amount of power since power is always supplied to the CCFL, has a color reproduction rate of about 70% compared to the CRT, and may cause environmental pollution problems due to the addition of mercury.

As a substitute for solving the above problems, research on a backlight unit using a light emitting diode (LED) has been actively conducted. When the LED is used as a backlight unit, the LED array can be partially turned on and off, which can drastically reduce the power consumption.In the case of the Red Green Blue (RGB) LED, the National Television System Committee (NTSC) Television System Committee) Provides more vivid picture quality to consumers by exceeding 100% of the color reproduction range specification.

1 is an exploded perspective view of a general LCD module.

Referring to FIG. 1, the LCD module includes a top case, a board assembly, a panel guide, and a backlight assembly. The backlight assembly consists of an LED array, a bottom cover, a light guide plate and an optical sheet.

2 is a view showing the heat flow of the edge-type backlight unit.

In general, the backlight unit converts the light emitted from the LED package 30 into a surface light source using the light guide plate 40. At this time, the light guide plate 40 may be expanded due to the high temperature of the LED package 30 to damage the LED package 30, thereby reducing the life of the product.

FIG. 3 is a diagram illustrating a deformation of the light guide plate 40, and FIG. 4 is a diagram illustrating a crack of the LED package 30.

Considering the heat flow of the edge type backlight unit as shown in FIG. 2, the light guide plate 40 may be deformed 50 as illustrated in FIG. 3 by the radiant heat of the LED, as illustrated in FIG. 4. As such, there is a problem that a crack 60 may occur in the LED package 30.

Embodiments provide a backlight unit having a long lifetime by maximizing heat dissipation and minimizing thermal resistance.

The backlight unit of the embodiment includes a light guide plate; A light source module disposed on at least one side of the light guide plate; And a heat dissipation part including a support part supporting the light source module and a bent part integrally extending from the support part, wherein the bent part comprises: a plurality of first segments disposed in a first direction; And a plurality of second segments disposed in a second direction different from the first direction, wherein the width of the first segment, the width of the second segment disposed closest to the light source module, and the farthest from the light source module At least one of the width of the second segment and the width of the first segment connecting the neighboring second segment are determined to maximize heat dissipation.

The width of the second segment may be larger as the closer to the light source module, the width of the first segment may be equal to each other, the width of the first segment is 10 mm to 15 mm, the closest to the light source module The width of the second segment disposed is 2 mm to 4 mm, the width of the second segment disposed furthest from the light source module is 1.5 mm to 3 mm, and the width of the first segment connecting the neighboring second segments May be between 4 mm and 7 mm.

In addition, the width of the first segment is 15 mm, the width of the second segment disposed closest to the light source module is 2.75 mm, the width of the second segment disposed farthest from the light source module is 1.9 mm, The width of the first segment connecting the second segment may be 6.2 mm.

The light source module includes a substrate disposed on the support; A lead frame disposed on the substrate; And a light emitting device disposed on the lead frame, wherein at least one of a thickness and an area of the lead frame is determined to minimize thermal resistance of the light source module.

The light source module further includes an adhesive disposed between the lead frame and the light emitting element,

The thickness of the adhesive can be determined to minimize the thermal resistance of the light source module. The light source module may further include a molding part surrounding the light emitting device, and at least one of a thickness and an area of the molding part may be determined to minimize thermal resistance of the light source module.

The lead frame may have a thickness of 0.4 mm to 0.8 mm, and the area of the lead frame may be 180 mm 2 to 210 mm 2. The thickness of the adhesive may be 0.01 mm to 0.02 mm. The molding part may have a thickness of 0.3 mm to 0.8 mm, and the molding part may have an area of 180 mm 2 to 210 mm 2.

According to another embodiment, the backlight unit may include a light guide plate; A light source module disposed on at least one side of the light guide plate; And a heat dissipation part including a support part supporting the light source module and a bent part extending integrally from the support part, wherein the light source module comprises: a substrate disposed on the support substrate; A lead frame disposed on the substrate; A light emitting element disposed on the lead frame; An adhesive disposed between the lead frame and the light emitting element; And a molding part surrounding the light emitting device, wherein at least one of the thickness of the lead frame, the area of the lead frame, the thickness of the adhesive, the thickness of the molding part, and the area of the molding part minimizes thermal resistance of the light source module. Is determined.

Since the back light unit of the embodiment has a structure in which the heat dissipation portion can maximize heat dissipation and the LED package has a structure in which the heat resistance is minimized, the deformation of the light guide plate due to heat can be alleviated, which not only increases the life of the product but also reduces the volume. Can be.

1 is an exploded perspective view of a general LCD module.
2 is a view showing the heat flow of the edge-type backlight unit.
3 is a diagram illustrating a deformation of the light guide plate.
4 is a diagram illustrating a crack of an LED package.
5 is a view illustrating an appearance of a backlight unit according to an embodiment.
6 is a partial perspective view of an edge type backlight unit according to an embodiment.
7A and 7B show an enlarged perspective view and a cross-sectional view of only the LED assembly at the side of the backlight unit illustrated in FIGS. 5 and 6, respectively.
8A-8C show perspective and cross-sectional views, respectively, of an LED package, which is the light source illustrated in FIGS. 6, 7A, and 7B.
9 is a diagram illustrating a scattering plot of an LED package.
10A to 10E are graphs showing thermal resistance for the factor of each part of the LED package.
11A and 11B are diagrams illustrating a temperature distribution depending on a position of an LED.
12 is a diagram illustrating a scattering plot of a backlight unit.
13A to 13E are graphs showing temperature changes with respect to respective widths of the heat dissipation unit.
14A to 14C show the temperature distribution, the heat distribution and the temperature distribution of the LED package, respectively, derived by the optimum value.
15A to 15C are graphs of temperature distributions between initial values and optimal values and comparisons thereof.
16 illustrates a display module having a backlight unit according to an embodiment.
17 illustrates a display device according to an embodiment.
18 is a diagram illustrating a display device according to another exemplary embodiment.

Hereinafter, embodiments will be described with reference to the accompanying drawings.

In the description of the present embodiment, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) on or under includes both the two elements being directly in contact with each other or one or more other elements being indirectly formed between the two elements.

Also, when expressed as "on" or "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

5 is a view illustrating an appearance of a backlight unit according to an embodiment.

6 is a partial perspective view of an edge type backlight unit according to an embodiment.

5 and 6, the backlight unit according to the embodiment includes a top case 110, a display panel 112, an optical member 114, a guide panel 116, a bottom cover 118, The heat dissipation unit 120, the light source module 130, and the light guide plate 140 are included.

The top case 110 may be connected to the guide panel 116, and the guide panel 116 may support the display panel 112. Subsequently, the light guide plate 140 may be formed of an acrylic resin such as polymethylmethacrylate (PMMA), polyethylene terephthlate (PET), cyclic olefin copolymers (COC), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), and MS (Mathacylate). styrene) resin.

Subsequently, an optical member 114, which may be supported by the guide panel 116, may be disposed on an upper surface of the light guide plate 140. Here, the optical member 114 is to diffuse the light emitted through the light guide plate 140, and may form an uneven pattern on the upper surface to increase the diffusion effect.

In addition, the optical member 114 may be formed of several layers, and the uneven pattern may be on the top layer or the surface of any one layer. In addition, the uneven pattern may have a stripe shape disposed along the light source module 130. In some cases, the optical member 114 includes at least one sheet, and may optionally include a diffusion sheet, a prism sheet, a brightness enhancement sheet, and the like. Here, the diffusion sheet diffuses the light emitted from the light source module 130, the prism sheet guides the diffused light to the light emitting region, and the luminance diffusion sheet enhances the luminance.

7A and 7B show an enlarged perspective view and a cross-sectional view of only the LED assembly at the side portion 100 of the backlight unit illustrated in FIGS. 5 and 6, respectively. The LED assembly includes a heat dissipation unit 120 and a light source module 130.

Referring to FIGS. 7A and 7B, the heat dissipation part 120 may include a support part 121 and curved parts 122 to 126. The support part 121 of the heat dissipation part 120 supports the light source module 130, and the bent parts 122 to 126 extend integrally from the support part 121. The heat dissipation unit 120 may be made of aluminum (Al).

The bends 122-126 include first and second segments 122-126. The first segments 122, 124, and 126 are disposed in a first direction, and the second segments 123 and 125 are disposed in a second direction different from the first direction. The first-first segment 122 of the first segments 122, 124, and 126 extends in the first direction from the support 121, and the second-first segment 123 of the second segments 123 and 125 is The first-second segment 122 extends in the second direction, the first-second segment 124 extends from the second-first segment 123 in the first direction, and the second-second segment 125 The first-second segment 124 extends in the second direction, and the first-third segment 126 extends from the second-second segment 125 in the first direction.

The heat dissipation part 120 illustrated in FIG. 7B is illustrated as having only three first segments 122, 124, 126 and two second segments 123, 125, but embodiments are not limited thereto. That is, the heat dissipation unit 120 may include more or fewer first and second segments.

According to the embodiment, the widths W3 and W4 of the first-first and first-third segments 122 and 126, and the width W1 of the second-first segment 123 disposed closest to the light source module 130. ), The width of the second-second segment 125 disposed farthest from the light source module 130 (or disposed further than the second-first segment 123 from the light source module 130) and the neighboring second At least one of the width W5 of the first-second segment 124 connecting the segments 123 and 125 is determined to maximize heat dissipation of the LED chip, which is a light emitting element of the backlight unit. That is, the widths W1 to W5 have an optimum value that can maximize heat dissipation of the backlight unit. The optimum values of the widths W1 to W5 will be described later in detail.

In addition, the widths of the second segments 123 and 125 may be larger as they are closer to the light source module 130. This is because the heat is generated closer to the light source module 130 to further promote heat dissipation. That is, the width W1 of the second-first segment 123 may be larger than the width W2 of the second-second segment 123. In addition, the widths W3 and W4 of the first segments 122 and 126 may be the same but are not limited thereto.

6, 7A, and 7B, the light source module 130 includes a substrate 132 disposed on the support 121 and at least one light source 134 disposed on the substrate 132. can do. Here, the light source 134 may be an LED package.

The substrate 132 may be formed with an electrode pattern for electrical connection to the LED package 134, and is made of any one material selected from polyethylene terephthalate (PET), glass, polycarbonate (PC), and silicon (Si). It may be a printed circuit board (PCB) or may be formed in a film form.

In addition, the substrate 132 may selectively use a single layer PCB, a multilayer PCB, a ceramic substrate, a metal core PCB, or the like.

8A-8C show perspective and cross-sectional views, respectively, of the LED package 134, which is the light source illustrated in FIGS. 6, 7A, and 7B. That is, FIGS. 8A and 8C show exploded perspective views of the LED package 134, and FIG. 8B shows a cross-sectional view of the LED package 134. 8B and 8C, the reflector 208 illustrated in FIG. 8A is omitted.

8A to 8C, the LED package 134 includes a molding part 202, a light emitting device 204, an adhesive 206, a reflecting part 208, and a lead frame 210.

The light emitting element 204 may be an LED chip, and may be, for example, a side view type light emitting diode. In some cases, the LED chip 204 may be a top view type light emitting diode.

The LED chip 204 may be composed of a blue LED chip or an ultraviolet LED chip, or a combination of at least one or more of a red LED chip, a green LED chip, a blue LED chip, a yellow green LED chip, and a white LED chip. It may also be configured in a package form.

Here, the white LED may be implemented by combining yellow phosphor on the blue LED, or simultaneously using red phosphor and green phosphor on the blue LED, and yellow phosphor on the blue LED. Yellow phosphor, red phosphor, and green phosphor may be simultaneously used.

The lead frame 210 is disposed on the substrate 132 and is connected to the substrate 132 by solder 212 and includes first and second lead frames electrically separated from each other, and the LED chip 204 It serves to provide power. In addition, the first and second lead frames 210 may serve to increase light efficiency by reflecting light generated from the LED chip 204, and discharge heat generated from the LED chip 204 to the outside. It can also play a role.

The LED chip 204 may be electrically connected to the first and / or second lead frame 210 by any one of a wire method, a flip chip method, or a die bonding method.

The LED chip 204 may be attached to the lead frame 210 by a paste adhesive 206. That is, the adhesive 206 is disposed between the lead frame 210 and the light emitting element 204. The reflector 208 serves to reflect the light emitted from the LED chip 204 toward the side to be emitted upward.

The molding part 202 may surround and protect the LED chip 204. The molding part 202 may include a phosphor to change the wavelength of light emitted from the LED chip 204. The material of the molding part 202 may be silicon, for example, but is not limited thereto.

In particular, referring to FIG. 8C, the thickness T1 and area A1 of the lead frame 210 and the thickness T2 of the adhesive 206, in order to minimize the thermal resistance of the LED chip 204 according to the embodiment. At least one of the thickness T3 and the area A2 of the molding part 202 may be determined. Here, the area A1 of the lead frame is expressed by the product of the width W6 of the lead frame 210 and the length L1, and the area A2 of the molding part 202 is the width (of the molding part 202). W7) and the length L2.

Hereinafter, the optimum values of the factors T1 to T3, A1, and A2 of the units 202, 206, and 210 for minimizing the thermal resistance of the LED chip 134 are derived as follows. To this end, 64 LED packages are used, and the light source module 130 is disposed on one side of the light guide plate 140. Since the thickness, not the width W1 to W5 of each segment of the heat dissipation part 120 depends on the thickness of the light guide plate 140 and the height of the light incident part of the LED package 134, a description thereof will be omitted.

First, the initial value, the lower limit, and the upper limit of each factor (W1 to W5, T1 to T3, A1, and A2) in each of the heat radiating unit 120 and the LED package 134 are set as shown in Tables 1 and 2 below.

division Initial value Lower limit maximum W1 1.4 mm 1.4 mm 4.0 mm W2 1.4 mm 1.4 mm 4.0 mm W3 10 mm 9 mm 15 mm W4 10 mm 9 mm 15 mm W5 6.2 mm 6.2 mm 7.6 mm

division Initial value Lower limit maximum T3 0.8 mm 0.5 mm 1.2 mm A1 180 ㎜ 170 ㎡ 210 ㎡ T2 0.02 mm 0.01 mm 0.05 mm T1 0.6 mm 0.4 mm 1.0 mm A2 180 ㎜ 170 ㎡ 210 ㎡

When interpreting the LED package 134, for convenience, the value of the factors T1, A1, T2, T3, and A2 is minimized using the thermal resistance network model as illustrated in FIG. 8B. In FIG. 8B, Ta may be 25 ° C. as the ambient temperature of the LED package 134, Rconv represents the convection thermal resistance, Rpa represents the thermal resistance of the paste adhesive 206, and Rcu represents the lead frame ( Thermal resistance of 210, Rso denotes thermal resistance of solder 212, and RAl denotes thermal resistance of aluminum substrate 132; In addition, the temperature of the junction of the LED chip 204 and the molding part 202 is called Tj.

In this case, the thermal resistance due to conduction is expressed as in Equation 1 below, and the thermal resistance due to convection is expressed as in Equation 2.

Where L is the length of the heat transfer path, k is the conductivity, A is the cross-sectional area of the heat transfer path, and h is the heat transfer coefficient, respectively.

Much research has been done on the factors affecting thermal properties, and based on previous studies on the physical relationship between factors and property values, the spatial arrangement of the LHD (Latin Hyper-Cube Design), which spreads the test points evenly and randomly within the design area The factor levels were randomly placed by the method. The number of experiments was assumed to be 5 factors, and the number of experiments was determined by the nSAT (number of saturation point) method in consideration of being expressed as a polynomial of n-th relationship between the factors and the response values.

Here, nSAT is represented by Equation 4 below.

Here, NDV represents the number of design variables.

The appropriate number of experiments is 1.5 * NSAT when the number of arguments is 10 or less and 10 * NDV when the number of factors is 11 or more.

FIG. 9 is a diagram illustrating a scattering plot of the LED package 134. Here, SiliconeThick, SiliconeArea, PasteThick, LeadArea, LeadThick, and ThetaJa correspond to T3, A2, T2, A1, T1 and thermal resistance, respectively.

The scattering plot for the above experiment is as shown in FIG. 9.

The factor that strongly correlates with the thermal resistance of the LED package 134 was analyzed by the thickness T2 of the adhesive 206. Correlation with the lead frame 210 appears relatively small within a given design range, and the thermal resistance value decreases as the area A2 of the silicon molding 202 increases. The optimum level (point / point) of the factor that minimizes thermal resistance within the above experimental values was calculated as shown in Table 3 below.

T1 A1 T2 T3 A2 Heat resistance Optimal point 0.72 mm 197.9 ㎜ 0.02 mm 0.66 mm 203.2 ㎜ 320.03 K / W Initial value 0.8 mm 180 ㎜ 0.02 mm 0.8 mm 180 ㎜ 364.6 K / W

Referring to Table 3, the thermal resistance value was reduced by 12% compared to the initial value at the optimum point obtained in the tested internal region, but the area A2 of the silicon molding portion 202 was increased and the thickness of the adhesive 206 ( T2) did not change. In order to find the part where the thermal resistance value can be further minimized, optimization modeling was performed to calculate the optimized factor.

The design factor level of the optimal design was derived after generating the approximate model. Approximate models were generated as nonlinear models based on previous studies and experiences. Derivation of the optimization level is adopted the STDQAO (Sequential Two-Point Diagonal Quadratic Approximate Optimization) method, the basic functional model is shown in the following equation (5).

Equation 5 described above is a numerical equation of Two-Point Diagonal Quadratic Approximate Optimization (TDQAO).

10A to 10E are graphs showing thermal resistance for the factors T1 to T3, A1, and A2 of the LED package 134, and FIGS. 10A, 10B, 10C, 10D, and 10E are T1, A1. , T2, T3, and A2 are graphs showing thermal resistance for each.

10A through 10E are regression models, and have the following equation (6).

Here, x ₁ , x ₂ , x ₃ , x ₄ and x _{5 correspond} to T3, A2, T2, A1 and T1, respectively.

Response characteristics for each factor are as illustrated in FIGS. 10A to 10E, and response characteristics considering all factors were also calculated. The adjusted explanatory rate R ² _adj of the optimization model is Higher than 99% was derived, the optimal value of all the factors (optimal value) was calculated as shown in Table 4.

T1 A1 T3 A2 T2 Heat resistance Optimal point 0.72 mm 197.9 ㎜ 0.66 mm 203.2 ㎜ 0.02 mm 320.03 K / W Initial value 0.8 mm 180 ㎜ 0.8 mm 180 ㎜ 0.02 mm 364.6 K / W Optimum value 0.4 mm 180 ㎜ 0.5 mm 210 ㎡ 0.01 mm 306.2 K / W

Referring to Table 4, when each factor (T1 to T3, A1, A2) was determined as the optimal value, the thermal resistance showed a 16% reduction compared to the initial value of each factor. 4% less than the best point due to Of Experiment.

Referring to Table 4, according to an embodiment, to minimize the thermal resistance value, the thickness T1 of the lead frame 210 may be 0.4 mm to 0.8 mm, for example 0.4 mm, of the lead frame 210. The area A1 may be between 180 mm 2 and 210 mm 2, for example 180 mm 2, and the thickness T2 of the adhesive 206 may be between 0.01 mm and 0.02 mm, for example 0.01 mm, and the thickness of the molding part 202. T3 may be 0.3 mm to 0.8 mm, for example 0.5 mm, and the area A2 of the molding part 202 may be 180 mm 2 to 210 mm 2, for example 210 mm 2.

Hereinafter, in the backlight unit, the factors W1 to W5 of the first and second segments 122 to 126 of the heat dissipation unit 120 to maximize heat dissipation of the LED will be described below.

11A and 11B are diagrams illustrating a temperature distribution depending on a position of an LED.

In order to proceed with the initial analysis of the backlight unit, the temperature distribution of the LED package 134 is as illustrated in FIGS. 11A and 11B. For analysis, the total number of interwoven grid cells divided by the backlight unit is about 6.3 million, and the main physical properties are shown in Table 5 below.

ingredient Bottom cover (118) Heat dissipation unit 120 pad Board 132 matter EGI Al 6063 silicon Al 5052 Conductivity (W / m-K) 62.5 180 0.8 138

In Table 5, the pad means a pad for bonding the heat dissipation unit 120 and the substrate 132, the substrate 132 is a PCB, the heat dissipation unit 120 is made of aluminum (Al).

The experiment was carried out in an environment with an air temperature of 25 ° C., and a static analysis was performed. Only the thermal conductivity of the material was considered in the analysis of the steady state, and the LED package 134 temperature distribution was examined from the bottom to the top of the backlight unit, and the temperature of the top surface of the LED package 134 increases as it goes toward the center. I could confirm it. Max Temp increased to 100.6 ° C. Using this maximum temperature as a reaction value, an optimum design was performed in which the heat radiation was maximized, that is, the temperature of the heat was minimized.

With the above-mentioned widths W1 to W5 as variables, the optimization design was carried out with the restraint condition as a part other than the item where the temperature of the LED package 134 becomes the minimum. Experimental point placement was performed by orthogonal array method in order to remove information about meaningless interaction, reduce the number of experiments, or obtain information on other factors using meaningless information.

12 is a diagram illustrating a scattering plot of a backlight unit. Here, X1, X2, X3, X4, X5 and Max Temp correspond to the widths W3, W1, W5, W2, W4 and the maximum temperatures, respectively.

To make an approximation model, the experimental points were placed as illustrated in FIG. 12 by the standard orthogonal array L ₃₂ (4 ⁹ ) taking into account the minimum experimental points required.

In the backlight unit, the width W3 of the maximum correlation of the LEDs shows a negative correlation. Among these experimental data, the minimum temperature was about 5% lower than the initial value. Optimal points compared to the initial values for each factor are shown in Table 6 and FIG.

W1 W2 W3 W4 W5 Max Temp (℃) Optimal point 3.13 mm 2.27 mm 15 mm 15 mm 7.13 mm 95.5 Initial value 1.4 mm 1.4 mm 10 mm 10 mm 6.2 mm 100.6

An approximation model was generated through Table 6.

13A to 13E are graphs showing temperature changes with respect to each of the widths W1 to W5 of the heat dissipation unit 120.

The approximation model generated a non-linear model in a similar manner to the experiment of the LED package 134 described above, and the model is as illustrated in FIGS. 13A-13E. The change in temperature caused by the change in width W5 was not reflected. This can be seen as a small correlation coefficient of the width W5 is calculated.

13A to 13E are regression models having equations such as Equation 7 below.

Here, x ₁ , x ₂ , x ₃ , x ₄ and x _{5 correspond} to the widths W3, W1, W5, W2 and W4, respectively.

Response characteristics for each of the widths W1 to W5 are as illustrated in FIGS. 13A to 13E, and an optimum value considering all the widths W1 to W5 is derived as shown in Table 7 below.

W1 W2 W3 W4 W5 Max Temp (℃) Optimal point 3.13 mm 2.27 mm 15 mm 15 mm 7.13 mm 95.5 Initial value 1.4 mm 1.4 mm 10 mm 10 mm 6.2 mm 100.6 Optimum value 2.75 mm 1.9 mm 15 mm 15 mm 6.2 mm 95.4

Referring to Table 7, the optimum point is similar to the temperature value in the experimental point, but the width (W1, W2, W5) was calculated with a smaller value in terms of dimensions.

14A to 14C show the temperature distribution, the heat distribution and the temperature distribution of the LED package 134, respectively, derived by the optimum value.

When the solution calculated by the above-described approximation model is simulated, the results are as shown in FIGS. 14A to 14C and show similar values to the solutions obtained from the approximation model.

15A to 15C are graphs of temperature distributions between initial values and optimal values and comparisons thereof. That is, FIG. 15A shows the temperature distribution of the initial value, FIG. 15B shows the temperature distribution of the optimum value, and FIG. 15C is a graph showing the temperature distribution of the initial value 300 and the temperature distribution of the optimum value 302. .

15A to 15C, when the widths W1 to W5 of the first and second segments 122 to 126 are determined as described above, it can be seen that heat dissipation of the backlight unit is maximized.

Referring to Table 7, according to an embodiment, the widths W3 and W4 of the first segments 122 and 126 may be 10 mm to 15 mm, for example 15 mm. The width W1 of the second segment 123 disposed closest to the light source module 130 may be 2 mm to 4 mm, for example 2.75 mm. The width W2 of the second segment 125 disposed furthest from the light source module 130 may be 1.5 mm to 3 mm, for example 1.9 mm. The width W5 of the first segment 124 connecting the neighboring second segments 123 and 125 may be 4 mm to 7 mm, for example 6.2 mm.

In the above, the optimum values of each factor (W1 to W4, T1 to T3, A1, A2) were derived by examining the temperature distribution of the heat dissipation unit 120 and the LED package 134 of the backlight module. In order to find the optimal value, the parameters of each part were first set as shown in Tables 1 and 2, and experimental points were placed through the Optimal Latin Hypercube Design (OLHD) and Orthogonal Array (OA) experiments for the upper and lower ranges. In addition, an approximate model was generated from each experimental point result, and the optimal value of the optimization level was derived through the STDQAO method. Through the optimal values of these factors (W1 to W5, T1 to T3, A1, A2), the following results were obtained.

First, the thermal resistance in the LED package 134 could be reduced by 16%.

Next, based on the optimal values of the above-described factors (T1 ~ T3, A1, A2), it was possible to optimize the heat sink (heat sink) of the light source module to obtain a temperature reduction of about 5% compared to the initial value.

Next, the approximate model of the backlight unit showed the highest temperature similar to the minimum value shown in the batch experiments, but achieved a volume reduction of about 4%.

Finally, the optimization of each factor (T1 to T3, A1, A2, W1 to W4) of the LED package 134 and the heat dissipation part 120 (ie, using an optimal value) is about 7.5% of the initial value. The effect of temperature reduction was confirmed.

Hereinafter, a display module having a backlight unit according to an embodiment will be described with reference to the accompanying drawings.

16 illustrates a display module having a backlight unit according to an embodiment.

As shown in FIG. 16, the display module 400 may include a display panel 420 and a backlight unit 500. Here, the backlight unit 500 corresponds to the backlight unit described above with reference to FIGS. 5 to 15C.

The display panel 420 includes a color filter substrate 422 and a thin film transistor (TFT) substrate 424 bonded to face each other to maintain a uniform cell gap, and a liquid crystal between the two substrates 422 and 424. A layer (not shown) may be interposed.

The color filter substrate 422 includes a plurality of pixels including red (R), green (G), and blue (B) sub-pixels, and generates an image corresponding to the color of red, green, or blue when light is applied. You can.

The pixels may be composed of red, green, and blue subpixels, but the red, green, blue, and white (W) subpixels constitute one pixel, but are not necessarily limited thereto.

The TFT substrate 424 may switch a pixel electrode (not shown) as a device in which switching elements are formed.

For example, the common electrode (not shown) and the pixel electrode may change the arrangement of molecules of the liquid crystal layer according to a predetermined voltage applied from the outside.

The liquid crystal layer is composed of a plurality of liquid crystal molecules, and the liquid crystal molecules change their arrangement corresponding to the voltage difference generated between the pixel electrode and the common electrode.

As a result, the light provided from the backlight unit 500 may be incident on the color filter substrate 422 corresponding to the change in the molecular arrangement of the liquid crystal layer.

In addition, an upper polarizer 426 and a lower polarizer 428 may be disposed above and below the display panel 420, and more specifically, an upper polarizer 426 may be disposed on an upper surface of the color filter substrate 422. The lower polarizer 428 may be disposed on the bottom surface of the TFT substrate 424.

Although not shown, a gate and a data driver for generating a driving signal for driving the display panel 420 may be provided on the side of the display panel 420.

As shown in FIG. 16, the display module 400 may be configured by closely placing the backlight unit 500 on the display panel 420.

For example, the backlight unit 500 may be adhered to and fixed to the lower side of the display panel 420, more specifically, the lower polarizer 428, for which the lower polarizer 428 and the backlight unit 500 may be fixed. An adhesive layer (not shown) may be formed on the substrate.

As such, by forming the backlight unit 500 in close contact with the display panel 420, the overall thickness of the display device may be reduced to improve appearance, and an additional structure for fixing the backlight unit 500 may be removed. The structure and manufacturing process of the display device can be simplified.

In addition, by removing the space between the backlight unit 500 and the display panel 420, it is possible to prevent the malfunction of the display device due to the infiltration of foreign matter into the space or the degradation of the image quality of the display image.

17 and 18 illustrate a display device according to an embodiment.

First, as shown in FIG. 17, the display apparatus 1 is provided in the display module 400, the front cover 600, the back cover 650, and the back cover 650 surrounding the display module 400. The driving unit 660 may include a driving unit cover 670 surrounding the driving unit 660.

The front cover 600 may include a front panel (not shown) of a transparent material that transmits light, and the front panel protects the display module 400 at regular intervals, and the light emitted from the display module 400. Through the transmission, the image displayed on the display module 400 is viewed from the outside.

In addition, the front cover 600 may be made of a flat plate without the window 600a.

In this case, the front cover 600 may be made of a transparent material that transmits light, for example, injection molded plastic.

As such, when the front cover 600 is formed of a flat plate, the frame can be removed from the front cover 600.

The back cover 660 may be combined with the front cover 600 to protect the display module 400.

The driving unit 660 may be disposed on one surface of the back cover 650.

The driver 660 may include a drive controller 660a, a main board 660b, and a power supply unit 660c.

The driving control unit 660a may be a timing controller. The driving control unit 660a may be a driving unit for adjusting an operation timing of each driver IC of the display module 400. The main board 660b may include a V sink, an H sink, and an R in the timing controller. The driving unit transfers the G and B resolution signals, and the power supply unit 660c may be a driving unit that applies power to the display module 400.

The driver 660 may be provided in the back cover 650 and may be wrapped by the driver cover 670.

The back cover 650 may be provided with a plurality of holes to connect the display module 400 and the driving unit 660, and may be provided with a stand 680 supporting the display device 1.

18, the driving control unit 660a of the driving unit 660 may be provided in the back cover 650, and the main board 660b and the power board 660c may be provided in the stand 680. have.

In addition, the driver cover 670 may wrap only the driver 660 provided in the back cover 650.

In the embodiment, the main board 660b and the power board 660c are separately configured, but may be formed as one integrated board, but the present invention is not limited thereto.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of illustration, It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

1: display device 110: top case
112: display panel 114: optical member
116: guide panel 118: bottom cover
120: heat radiating portion 121: support portion
122 to 126: segment 130: light source module
132: substrate 134: light source
140: light guide plate 202: molding part
204: light emitting element 206: adhesive
208: reflector 210: lead frame
212 solder 400 display module
420: display panel 422: color filter substrate
424: TFT substrate 426: upper polarizing plate
428: lower polarizer 500: backlight unit
600: front cover 650: back cover
660: drive unit 670: drive unit cover

Claims (12)

A light guide plate;
A light source module disposed on at least one side of the light guide plate; And
And a heat dissipation part including a support part supporting the light source module and a bent part integrally extending from the support part.
The bent portion
A plurality of first segments disposed in a first direction; And
A plurality of second segments arranged in a second direction different from the first direction,
A width of the first segment, a width of the second segment disposed closest to the light source module, a width of the second segment disposed farthest from the light source module, and a width of the first segment connecting the neighboring second segments At least one backlight unit determined to maximize heat dissipation. The backlight unit of claim 1, wherein a width of the second segment is closer to the light source module. The backlight unit of claim 1, wherein the widths of the first segments are equal to each other. The method of claim 1, wherein the width of the first segment is between 10 mm and 15 mm, and the width of the second segment disposed closest to the light source module is between 2 mm and 4 mm and is disposed farthest from the light source module. And the width of the two segments is 1.5 mm to 3 mm, and the width of the first segment connecting the neighboring second segments is 4 mm to 7 mm. The width of the first segment is 15 mm, the width of the second segment disposed closest to the light source module is 2.75 mm, and the width of the second segment disposed farthest from the light source module is 1.9. And a width of the first segment connecting the neighboring second segments is 6.2 mm. The method of claim 1, wherein the light source module
A substrate disposed on the support;
A lead frame disposed on the substrate; And
A light emitting element disposed on the lead frame;
At least one of a thickness and an area of the lead frame is determined to minimize thermal resistance of the light source module. The method of claim 6, wherein the light source module further comprises an adhesive disposed between the lead frame and the light emitting element,
And a thickness of the adhesive is determined to minimize thermal resistance of the light source module. The light source module of claim 6, wherein the light source module further includes a molding part surrounding the light emitting device.
At least one of a thickness and an area of the molding part is determined to minimize thermal resistance of the light source module. The backlight unit of claim 6, wherein a thickness of the lead frame is 0.4 mm to 0.8 mm, and an area of the lead frame is 180 mm 2 to 210 mm 2. The backlight unit of claim 7, wherein the adhesive has a thickness of 0.01 mm to 0.02 mm. The backlight unit of claim 8, wherein the molding part has a thickness of 0.3 mm to 0.8 mm and an area of the molding part is 180 mm 2 to 210 mm 2. A light guide plate;
A light source module disposed on at least one side of the light guide plate; And
And a heat dissipation part including a support part supporting the light source module and a bent part integrally extending from the support part.
The light source module
A substrate disposed on the support substrate;
A lead frame disposed on the substrate;
A light emitting element disposed on the lead frame;
An adhesive disposed between the lead frame and the light emitting element; And
It includes a molding unit surrounding the light emitting element,
And at least one of the thickness of the lead frame, the area of the lead frame, the thickness of the adhesive, the thickness of the molding part, and the area of the molding part is determined to minimize thermal resistance of the light source module.

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