KR20080081545A

KR20080081545A - Liquid crystal display device

Info

Publication number: KR20080081545A
Application number: KR20070021672A
Authority: KR
Inventors: 김도윤; 백성훈
Original assignee: 엘지디스플레이 주식회사
Priority date: 2007-03-05
Filing date: 2007-03-05
Publication date: 2008-09-10

Abstract

An LCD device is provided to form various forms of reinforcing structures such as an uneven or a hollow portion in a metal board made of aluminum, thereby protecting the conductive metal pattern of the metal board and securing the reliability of the lighting of an LED. An LCD(Liquid Crystal Display) device includes a lower cover(220), at least one PCB(Printed Circuit Board)(230), and an LCD panel(210). At least one PCB includes a metal board(234) and an LED(Light Emitting Diode)(236). The metal board is arrayed and fixed on the lower cover. At least one of an upper side and a lower side of the metal board is formed unbalancedly to disperse weight. The LED is mounted on the upper side of the metal board to emit light. The LCD panel is spaced from the front of the PCB and fastened. At least an uneven portion is engraved along a major axis in the bottom surface of the metal board.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is a cross-sectional view of a liquid crystal display device according to the related art.

2 is a plan view showing the metal PCB structure of FIG.

3 is a plan view showing another structure of the metal PCB of FIG.

4 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

5A and 5B are views illustrating a manufacturing process of the metal PCB of FIG. 4.

Figure 6a is a side view showing the state of the force acting when assembling the metal PCB of Figure 4

6B is a cross-sectional view illustrating a state of a force acting when assembling the metal PCB of FIG. 4.

7 and 8 illustrate a modified structure of the metal PCB of FIG.

9 is a cross-sectional view according to another embodiment of the metal PCB of FIG. 4.

10 is a cross-sectional view according to another embodiment of the metal PCB of FIG. 4.

※※ Explanation of symbols for main parts of drawing ※※

230: lower cover 232: first reflecting plate

234, 334, 434, 534, 634: metal substrate

236, 336, 436, 536, 636: light emitting element

237, 537, 637: conductive material 238: second reflector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to improve the warpage phenomenon of a metal printed circuit board (LED) fixed by arranging LEDs in an LED backlight structure.

In general, a direct type back-light used in a large-scale liquid crystal display reflects light from a cold cathode fluorescent lamp to a liquid crystal panel in front of a reflective plate. At this time, a milky white scattering plate such as a diffuser plate is additionally disposed in the reflection path, so that light having a locally uniform illuminance is illuminated on the liquid crystal display. However, such a method has a problem of bringing the liquid crystal display to a large and complicated model due to the thickness problem of the backlight constituting the display.

In recent years, as one of the surface light source devices, the backlight is thinned and the brightness is also improved by using a light emitting diode (LED) having characteristics such as fast response speed, low power consumption, and semi-permanent lifetime. Most of all, this is the next generation LCD that can replace the cold cathode tube backlight device by reproducing natural color and high quality images compared to the existing cold cathode tube, and recognizing that it is an eco-friendly product that solves the afterimage problem and does not use mercury. It is regarded as a core component of.

Next, the direct type liquid crystal display device having the LED backlight device will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, the LCD includes a backlight including a lower cover 30 at a lower portion of the liquid crystal display, based on a main support 50 made of a synthetic resin or a mold of SUS STEEL having a substantially rectangular frame shape. The device (not shown) and the upper portion of the liquid crystal panel 10 are sequentially loaded and fastened. An upper cover 60 capable of fixing all of these covers the front edge of the liquid crystal panel 10 and is assembled and fastened to the main support 50 and the lower cover 30.

More specifically, first, a plurality of printed circuit boards (PCBs) 34 formed by forming at least one line of LEDs emitting light are arranged and fixed on the lower cover 30. In this regard, conventionally, about 8 inch PCBs are arranged based on a 32-inch LCD, and recently, in addition to solving the problem of high temperature heat generation associated with LEDs fixed on the PCBs. In order to use a metal PCB formed by coating a separate metal material such as a metal substrate on the back of the PCB.

Of course, the entire reflecting plate for reflecting light from the LEDs 36 to the front surface where the liquid crystal panel 10 is located before the plurality of PCBs 34 are arranged and fixed on the entire bottom surface of the lower cover 30. 32 is attached.

In addition, there is another reflecting plate 38 attached to each PCB (Printed Circuit Board; 34) on the upper side, compared with the reflecting plate 32 attached to the entire surface of the lower cover (30) The difference is slightly different in that it is attached by forming holes in the LED 36 area.

However, the above two reflectors 32 and 38 commonly form a coating film such as metal (Ag, Al) on a white polyester film as a reflective layer, and in some cases, silicon oxide in an acrylic solution It may be the scattering particles (SiO ₂₎ formed by curing a mixed ink.

Subsequently, a diffuser plate 42 for mitigating non-uniformity of light emitted from the LEDs 36 formed in an array on each PCB 34, and the front luminance of the light transmitted through the diffuser plate 42. The prism sheet 44 and the protective sheet 46 for protecting the prism sheet 44 and increasing the viewing angle are loaded.

After the configuration of the backlight is completed as described above, the main support 50 made of a molded product of synthetic resin or sus steel having a substantially rectangular frame shape is fastened next.

Thereafter, the liquid crystal panel 10 is stacked above the main support 50. Of course, the liquid crystal panel 10 is a thin film transistor array substrate and a color filter substrate are bonded to each other, and the liquid crystal panel 10 includes liquid crystals injected therebetween.

An upper cover 60 capable of fixing all of them covers four edges of the liquid crystal panel 10 and is assembled and fastened to the main support 50 and the lower cover 30.

2 is a view showing the LED backlight structure of Figure 1, Figure 3 is a view showing another structure of the LED backlight of FIG.

First, the PCB 34 shown in FIG. 2 is substantially a metal PCB. That is, an insulating layer is formed on a metal substrate made of aluminum (Al) or the like, and a plating layer is formed of copper (Cu) or the like on the insulating layer by electroplating, and then the copper forming the plating layer is precipitated again ( Outwardly to form a circuit pattern. The light emitting element 36 is mounted on the circuit pattern to be electrically conductive.

On the other hand, the PCB 44 shown in FIG. 3 is a tile type substrate that can be separated between a metal substrate such as aluminum and a substrate on which a circuit pattern is formed, and then attaches at least one LED substrate to each metal substrate. The conductive wires 48 are electrically connected to each other through the conductive wires 48 to emit light from the light emitting elements 46 on the PCB 44.

This can be seen as a way to prevent overproduction of products and solve cost problems by flexibly coping with LED backlight devices used in liquid crystal display devices of various sizes such as 32 inches and 42 inches.

However, such a conventional metal PCB has a circuit pattern formed on a plated layer on a metal substrate having a long bar shape of a rectangular shape having a height of about 1.6 mm, so that the LED backlight is substantially constructed using the metal PCB. In this case, an external force acts on the bar-shaped metal substrate during assembly by an operator or equipment, and an impact test of a liquid crystal display device, which causes bending of the metal PCB.

This results in cracking of the circuit pattern of the plating layer formed on the metal substrate, or the disconnection of the conductive wire to assist the electrical connection between the tile-type substrates attached on the metal substrate. It is a major cause.

Accordingly, the present invention forms a reinforcing structure of various shapes such as irregularities or hollows on a metal substrate made of aluminum or the like to improve such a problem, and in addition, the intaglio and hollow portions of the irregularities are formed. It is an object of the present invention to provide an LED backlight device and a liquid crystal display device for facilitating heat dissipation by forming a thermal conductive material such as grease in a pad.

And the achievement of this object can be further embodied by the present invention. That is, the liquid crystal display according to the exemplary embodiment of the present invention includes a lower cover; At least one comprising a metal substrate arranged and fixed on the lower cover and having at least one of upper and lower surfaces unbalanced to distribute the load, and a light emitting device mounted on the upper surface of the metal substrate to emit light. Printed Circuit Board (PCB); And it characterized in that it comprises a liquid crystal panel is fastened to be spaced apart (離隔) to the front of the PCB.

In addition, the liquid crystal display according to another embodiment of the present invention and the lower cover; At least one PCB comprising a metal substrate arranged on the lower cover and having at least one hollow formed therein to distribute the load, and a light emitting element mounted on an upper surface of the metal substrate to emit light; Circuit board); And it characterized in that it comprises a liquid crystal panel is fastened to be spaced apart (離隔) to the front of the PCB.

Then, the above configuration will be described in detail with reference to the accompanying drawings. 4 is a cross-sectional view illustrating a liquid crystal display device according to an exemplary embodiment of the present invention.

First, the lower cover 220 is made of aluminum (Al) or the like in consideration of thermal conductivity, and a metal substrate 234 on which unevenness is formed to satisfy a reinforcement structure against external forces. A light emitting element 236 mounted on an insulating layer, a plating layer on which a circuit pattern is formed on the insulating layer, and at least one array formed on the circuit pattern, and the heat from the light emitting element 236 in addition to the uneven portion. The lower PCB 220 arranges and fixes the metal PCB 230 including the thermally conductive material 237 to be efficiently discharged to the outside.

In addition, the metal PCB 230 may be formed on the lower surface of the metal substrate 234 made of a metal material in order to improve the warpage phenomenon which may occur due to external factors such as an operator or an assembly equipment when the LCD is assembled. By forming at least one unevenness or the like along the long axis direction, the upper and lower surfaces of the metal substrate 234 are unbalanced with each other, and in addition, the high temperature heat generated from the light emitting element 236 is lowered. In order to efficiently discharge to the outside through the cover 220, such as a material in which grease or silicon (Si) and aluminum oxide (Al ₂ O ₃ ) are mixed in the intaglio portion of the metal substrate 234 having the unevenness It is made by additionally forming a thermally conductive material 237.

Of course, prior to arranging and fixing the plurality of PCBs 230 on the entire bottom surface of the lower cover 220, the light from the LEDs 236 is reflected to the front surface where the liquid crystal panel 210 is located. Reflector plate 225 is attached.

In addition, there is another reflecting plate 240 attached to the upper side of each PCB 230, where the difference compared to the reflecting plate 225 attached to the front of the lower cover 220, the difference is the LED (236) A little different in that it forms and attaches a hole to the area.

However, the two reflecting plates 225 and 240 are formed on the white polyester film as a reflective layer on the white polyester film as a reflective layer, and in some cases, the acrylic reflector The scattering particles of silicon oxide (SiO ₂ ) are common in that they can be formed by curing the mixed ink.

Next, a diffuser plate 242 for alleviating the nonuniformity of the light emitted from the LED 236 array, a prism sheet 244 used for the purpose of increasing the front luminance of the light transmitted over the diffuser plate 242, and a prism And a protective sheet 246 that protects the sheet 244 and increases the viewing angle.

Next, the main support 250 made of a synthetic resin or sustainable mold having a substantially rectangular frame shape is fastened.

Thereafter, the liquid crystal panel 210 is stacked above the main support 250. Of course, the liquid crystal panel 210 is a thin film transistor array substrate and a color filter substrate bonded to each other, and includes a liquid crystal injected therebetween.

An upper cover 260 capable of fixing all of them covers four edge regions of the liquid crystal panel 210 and is assembled and fastened to the main support 250 and the lower cover 220.

5A and 5B illustrate the manufacturing process of the metal PCB 230 of FIG. 4 in more detail. In FIG. 5A, the metal substrate 234a is first supplied with a conductive material such as aluminum (Al), titanium (Ti), magnesium (Mg), etc. to the extruder, and then pushed out of the mold to be converted into a continuous body having a constant cross section. As the lower surface, a reinforcing structure for external force, such as irregularities, is formed.

For example, the reinforcing structure is at least one along the long axis direction of the upper half thickness (8 mm) on the lower surface of the metal substrate 234a formed in the form of a long bar having a thickness (or height) of 1.6 mm. It is preferable to form irregularities. However, the thickness of the unevenness will not be particularly limited.

In addition, the above-mentioned aluminum may be classified into various types in consideration of its material, tensile strength, and durability, and in the present invention, the thermal conductivity of the 50 series is 1.5 to 2 times better than that of the 50 series for cost reduction and thermal conductivity efficiency. Inexpensive 60 series materials are available.

The insulating layer 234b is formed on the metal substrate 234a formed as above by using an anodizing method or the like. Anodizing is a surface treatment method widely used in building materials, telecommunication equipment, optical devices, ornaments, automobile parts, etc., and forms a thin oxide film on the metal surface to protect the inside of the metal. It is mainly used for metals that make an oxide film on their own surface because the degree of reaction with oxygen is very high such as aluminum (Al), magnesium (Mg), titanium (Ti), and the like.

Anodizing is a method of artificially producing an oxide film having a uniform thickness by accelerating the oxidation of a metal surface by allowing a metal to act as an anode in a solution such as sulfuric acid. The aluminum is oxidized by oxygen generated at the anode to produce a film of aluminum oxide (Al ₂ O ₃ ). Since this film is very hard, highly corrosion resistant and extremely small porosity layer, it can be dyed in various colors, so anodizing is often performed on the metal surface not only for practical reasons such as corrosion resistance and abrasion resistance but also for aesthetic reasons. .

As described above, the plating layer 234c is formed by applying AC power to the surface of the metal substrate 234a having the oxide film layer formed as the insulating layer 234b by anodizing. Usually, a copper plating layer 234c is formed and is performed by an electroplating method. However, electroplating method using AC power is applied, not electroplating using DC power.

Electroplating using an alternating current power source is a kind of pulse plating, in which copper is deposited in pores of the oxide film layer, which is the insulating layer 234b. In general, electroplating uses a DC power supply. However, when the insulating layer 234b is formed on the surface of the metal substrate 234a as in the present invention, copper is deposited in the pores of the oxide film layer using the DC power supply, thereby forming a plating layer ( There is a limit to growing to 234c).

Accordingly, when the electroplating is performed by applying AC power to the metal substrate 234a, copper is precipitated from the pores of the oxide layer using the polarization phenomenon of the oxide layer, which is the insulating layer 234b, and as a result, a plating layer is formed on the oxide layer. 234c). Thus, by depositing copper from the pores of the oxide film layer to form a plating layer 234c, the adhesion between the copper plating layer 234c and the oxide film layer is excellent.

In addition, a circuit pattern is formed on the plating layer 234c formed on the surface of the metal substrate 234a to complete the printed circuit board. Of course, a method of forming a circuit pattern on the copper plating layer 234c may be variously made.

As described above, the metal PCB 230 is finished by fixing the LEDs 236 in an array, that is, in series, on the circuit pattern formed on the copper plating layer 234c.

The metal PCB 230 is substantially a metal PCB 230, as shown in Figure 5b to facilitate the heat dissipation to the outside when assembling the metal PCB 230 on the lower cover 220 of the liquid crystal display device. The pad thermally conductive material 237 having good temperature characteristics manufactured by mixing silicon (Si) and aluminum oxide (Al ₂ O ₃ ) may be additionally formed on the intaglio recessed portion of the _c ).

However, the same effect can be obtained by using grease prepared by mixing in a colloidal state by adding a metal soap and a small amount of water to the liquid mineral oil lubricant instead of the pad material. will be.

6A is a view showing an action state of the force viewed in the long axis direction when assembling the metal PCB 230 shown in FIG. As shown in the drawing, the metal PCB 230 has a force acting by an external worker on both sides of the long axis direction when the LCD is assembled, that is, the external force F1 acts as a force F2 in the center region. This becomes equal because the load F2 acting in the center region is dispersed by the uneven structure formed on the lower surface of the metal PCB 230.

FIG. 6B is a view showing an action state of a force in a short axis direction when assembling the metal PCB 230 shown in FIG. 6A. As shown in the figure, the load F2 acting on the intaglio portion due to the plurality of concave-convex shapes formed along the long axis direction of the metal PCB 230 is distributed to the embossed portion formed to protrude on both sides and the center region thereof.

Therefore, as described above, the distributed load F2 becomes equal to the external force F1 by the external worker of the metal PCB 230, which in turn prevents the bending of the metal PCB 230. .

Based on this, the distributed structure of the force formed on the lower surface of the metal PCB 230 shown in Figs. 4, 5A and 5B, and Figs. 6A and 6B has various modifications at equivalent levels of the above-mentioned concave-convex shape. This may be possible. For example, the concave-convex shape may not be formed in two, but may be formed in one concave-convex shape, or may be formed in three or more concave-convex shapes.

In addition, such a concave-convex shape may be deformed into a semicircular arcuate structure or triangular shape so as to non-equilibrate at least one of the upper and lower surfaces as shown in FIGS. 7 and 8. Of course, the number will not be particularly limited as above.

Such a structure can be further modified to a shape as shown in FIG. 9. In other words, by forming the concave-convex shape on the upper and lower surfaces of the metal substrate 534a, the upper and lower surfaces are non-equilibrium with each other, and then the intaglio portion of the upper surface is the insulating layer 534b described above and The conductive layer 534c for the circuit pattern may be formed, and the LED 536 may be fixed and arranged.

For example, assuming that the metal substrate 534a is formed to have a width of 1.6 mm, the intaglio portion of the uneven surface formed on the upper and lower surfaces may be formed to have a step of 0.5 mm. As a result, the metal substrate 534a after one unevenness is formed on the upper and lower surfaces thereof has an I shape.

In addition, as shown in FIG. 10, a method of forming a hollow in the center region of the metal substrate 634a may be appropriate. Of course, even in this case, the number of the hollow is not limited, and the principle of force dispersion and the like will be replaced by the above contents.

In addition to the shape of the hollow in addition to the square shown in the drawings it will be possible to change to a variety of shapes, such as round, oval, or triangle.

Of course, even in the above two cases, the dispersion structure of the various forces on the metal substrates 534a and 634a substantially raises the need to additionally form thermally conductive materials 537 and 637 such as grease. This is because it can be assembled on the lower cover to efficiently perform the function as a metal PCB.

In other words, in order to efficiently discharge heat from the LEDs 536 and 636 fixed and arranged on the upper sides of the metal substrates 534a and 634a to the outside through the lower cover, the thermally conductive materials 537 and 637 may be used. This is because it is utilized as a thermal path of the metal substrates 534a and 634a.

As a result of the configuration up to now, the liquid crystal display device according to the present invention protects the metal conductive pattern of the metal substrate by forming a reinforcing structure having various shapes such as irregularities or hollows on the metal substrate made of aluminum or the like. It is possible to secure reliability of lighting of LED.

In addition, heat dissipation from the metal substrate may be facilitated by forming pads with a thermally conductive material such as grease on the intaglio and hollow portions formed on the metal substrate.

In addition, in the case where the metal substrate is made of aluminum 60 series material and the thermal conductive material is formed as a pad in the reinforcing structure thereof, cost reduction and thermal conductivity efficiency may be improved.

Claims

Lower cover;

At least one comprising a metal substrate arranged and fixed on the lower cover and having at least one of upper and lower surfaces unbalanced to distribute the load, and a light emitting device mounted on the upper surface of the metal substrate to emit light. Printed Circuit Board (PCB);

And a liquid crystal panel which is spaced apart and fastened to the front surface of the PCB.

The liquid crystal display device according to claim 1, wherein at least one unevenness is formed on the lower surface of the metal substrate along the long axis direction.

The liquid crystal display of claim 1, wherein at least one semicircular shape is formed on a lower surface of the metal substrate along a major axis direction.

The liquid crystal display of claim 1, wherein at least one triangular shape is formed on a lower surface of the metal substrate along a major axis direction.

The liquid crystal display device according to claim 1, wherein when one unevenness is formed along the major axis direction of the upper and lower surfaces of the metal substrate, the shape of the metal substrate is "I" shaped.

The liquid crystal display of claim 1, wherein the metal substrate is formed of any one of aluminum (Al), magnesium (Mg), and titanium (Ti).

The liquid crystal display of claim 1, wherein the PCB is integrally formed with an insulating layer and a plating layer on which a circuit pattern is formed.

The PCB of claim 1, wherein a plurality of tile-type PCBs separately formed, including a plating layer having an insulating layer and a circuit pattern formed on the metal substrate, are attached to each other, and each tile PCB is electrically connected to each other. And a conductive wire is additionally formed.

The liquid crystal display device of claim 1, wherein a thermally conductive material is additionally formed at a portion that is non-equilibrium formed on the metal substrate.

The liquid crystal display of claim 9, wherein the thermally conductive material is a material formed by mixing silicon (Si) and alumina (Al ₂ O ₃ ).

10. The liquid crystal of claim 9, wherein the thermally conductive material is grease prepared by adding a metal soap and a small amount of water to a liquid mineral oil-based lubricating oil and mixing the mixture in a colloidal state. Display.

Lower cover;

At least one PCB comprising a metal substrate arranged on the lower cover and having at least one hollow formed therein to distribute the load, and a light emitting element mounted on an upper surface of the metal substrate to emit light; Circuit board);

The liquid crystal display of claim 12, wherein the metal substrate is formed of any one of aluminum (Al), magnesium (Mg), and titanium (Ti).

The liquid crystal display of claim 12, wherein the PCB is integrally formed with an insulating layer and a plating layer having a circuit pattern formed on the metal substrate.

The PCB of claim 12, wherein a plurality of tile-type PCBs separately formed, including a plating layer having an insulating layer and a circuit pattern formed on the metal substrate, are attached to each other, and each tile PCB is electrically connected to each other. And a conductive wire is additionally formed.

The liquid crystal display of claim 12, wherein the hollow is formed of any one of a rectangular shape, a circular shape, and an elliptic shape.

The liquid crystal display of claim 12, wherein a thermally conductive material is further formed in the hollow on the metal substrate.

The liquid crystal display of claim 17, wherein the thermally conductive material is a material formed by mixing silicon (Si) and alumina (Al ₂ O ₃ ).

18. The liquid crystal of claim 17, wherein the thermally conductive material is grease prepared by adding a metal soap and a small amount of water to a liquid mineral oil-based lubricating oil and mixing the mixture in a colloidal state. Display.