KR100971395B1 - Back Light Unit - Google Patents

Abstract

The present invention relates to a backlight unit having a lamp array in a diffuser plate and omitting an assembly structure required for a lamp housing. The backlight unit includes a diffusion plate having a plurality of holes spaced equidistantly from one side to the other, A plurality of lamps respectively formed in the plurality of holes, a reflector for covering the rear and side surfaces of the diffuser plate, and a cover bottom for covering the outer edges of the diffuser plate and the reflector.

Diffusion plate, lamp array, hole, insert type lamp

Description

BACKLIGHT UNIT [0001]

1 is a cross-sectional view schematically showing a liquid crystal display device including a general backlight unit

2 is a schematic cross-sectional view showing a conventional backlight unit of an edge type

Fig. 3 is a schematic cross-sectional view showing a backlight unit of a conventional direct-

4 is a cross-sectional view showing the backlight unit of the present invention

Figure 5 is an exploded perspective view of the lamp and the silicone rubber supporting the lamp of Figure 4;

Fig. 6 is an exploded perspective view showing a backlight unit having a plurality of lamps in the transparent diffusion plate of Fig.

Description of the Related Art [0002]

41: lamp 42: diffuser plate

43: reflector 44: cover bottom

45: silicon rubber 50: hole

51: voltage applying line

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a backlight unit having a lamp array in a diffuser plate and omitting an assembly structure necessary for a lamp housing.

CRT (Cathode Ray Tube), which is one of the commonly used display devices, is mainly used for monitors such as TVs, metering devices, and information terminal devices. However, due to its own weight and size, , It could not actively cope with the demand for weight reduction.

Therefore, in the trend of miniaturization and light weight of various electronic products, CRT has a certain limit in weight and size, and is expected to be replaced with liquid crystal display (LCD) using electric field effect, gas discharge A plasma display panel (PDP) and an electroluminescence display (ELD) using an electroluminescence effect. Among them, researches on liquid crystal display devices are being actively carried out.

Such a liquid crystal display device having advantages such as small size, light weight and low power consumption for replacing CRT has been developed to such a degree that it can sufficiently fulfill its role as a flat panel display device in recent years and can be used not only for a monitor of a laptop- Monitors, large information display devices, and the like, and the demand for liquid crystal display devices is continuously increasing.

The liquid crystal display device may be roughly divided into a liquid crystal panel for displaying an image and a driving part for applying a driving signal to the liquid crystal panel. The liquid crystal panel includes first and second glass substrates, And a liquid crystal layer injected between the first and second glass substrates.

Here, the first glass substrate (TFT array substrate) is provided with a plurality of gate lines arranged at a predetermined interval in one direction, a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines, A plurality of pixel electrodes formed in a matrix form in each pixel region defined by intersecting gate lines and data lines and a plurality of thin films that are switched by signals of the gate lines to transmit signals of the data lines to the pixel electrodes, A transistor is formed.

In addition, a second glass substrate (color filter substrate) is provided with a black matrix layer for shielding light in the portion excluding the pixel region, an R, G, and B color filter layers for expressing color hues, .

The first and second glass substrates are bonded together by a spacer having a certain space and having a liquid crystal injection hole, and the liquid crystal is injected between the two substrates.

On the other hand, since most of the liquid crystal display device is a light-receiving element that displays an image by adjusting the amount of a light source coming from the outside, a separate light source, that is, a backlight for irradiating light to the liquid crystal panel is necessarily required. Depending on the location where the lamp unit is installed, it is divided into an edge type and a direct type.

The light sources used here are EL (Electro Luminescence), LED (Light Emitting Diode), CCFL (Cold Cathode Fluorescent Lamp) and HCFL (Hot Cathode Fluorescent Lamp) The CCFL method is widely used in large-screen color TFT LCDs.

In the CCFL method, a fluorescent discharge tube in which mercury (Hg) gas containing argon (Ar), neon (Ne) and the like is sealed at a low pressure is used to utilize the penning effect. An electrode is formed at both ends of the tube. The cathode is formed in a plate-like shape. When a voltage is applied, the charge carriers in the discharge tube collide with the plate-like cathode by generating a secondary electron as in the sputtering phenomenon, Thereby forming a plasma.

These elements emit strong ultraviolet rays that again excite the phosphor, causing the phosphor to emit visible light.

Hereinafter, a conventional backlight unit will be described with reference to the accompanying drawings.

1 is a cross-sectional view schematically showing a liquid crystal display device including a general backlight unit.

1, a typical liquid crystal display device comprises a liquid crystal panel 1, a prism sheet 6, a diffusion plate 5, a lamp unit 2 and a reflection plate 4 in order from the top.

First, as described above, the liquid crystal panel 1 comprises an upper substrate on which a color filter array is formed, a lower substrate on which a thin film transistor array is formed, and a liquid crystal layer filled between the two substrates.

In the lamp unit 2, a fluorescent lamp array and a light guide plate for emitting light emitted from the lamp array toward the liquid crystal panel 1 are formed.                         

When a voltage is applied to the fluorescent lamp of each of the fluorescent lamp arrays, the residual electrons present in the fluorescent lamp move to the anode, the remaining electrons in motion collide with argon (Ar) and argon is excited to proliferate the positive ions, Cations collide with the cathode and emit secondary electrons.

When the discharged secondary electrons flow into the tube to initiate discharge, the flow of electrons due to the discharge collides with mercury (Hg) vapor and is ionized to emit ultraviolet rays and visible light, and the emitted ultraviolet rays are applied to the inner wall of the lamp And excites visible light to emit light.

A light guide plate (not shown) in the lamp unit surrounds the lamp unit. The wave guide guides the light emitted from the fluorescent lamp into the interior of the lamp unit, (Poly methyl methacrylate) resin is used.

The light incident efficiency of the light guide plate may be related to the light guide plate thickness, the lamp diameter, the distance between the light guide plate and the lamp, and the shape of the lamp reflector. In general, .

The light guide plate of the LCD backlight unit includes a light guide plate of a printing method, a light guide plate of a V-cut method, and a scattering light guide plate.

The diffusion material under the light guide plate is made of SiO2, particles, PMMA, solvent, or the like. At this time, the above-mentioned SiO 2 particles are used for light diffusion and have a porous particle structure. PMMA is also used to adhere the Si02 particles to the lower surface of the light guide plate.                         

The diffusion material is applied to the lower surface of the light guide plate in the form of a dot, and the area of the dot is gradually increased in order to obtain a uniform surface light source on the upper side of the light guide plate. That is, the area ratio occupied by the dots per unit area is small in the vicinity of the fluorescent lamp, and the area ratio occupied by the dots per unit area in the far side from the fluorescent lamp is large.

At this time, the shape of the dot may be various, and if the area ratio of the dots per unit area is the same, the same brightness effect can be obtained at the upper part of the light guide plate regardless of the shape of the dot.

The reflector 4 is installed under the lamp unit 2 so that the light emitted from the lamp unit 2 and directed downward enters into the lamp unit 2 again.

The diffusion plate 5 is provided on the light guide plate coated with the dot pattern to obtain a uniform luminance according to a viewing angle. The diffusion plate 5 may be made of PET (Poly Ethylene Terephtalate) PC (Poly Carbonate) resin is used, and on the upper surface of the diffusion plate 5, there is a particle coating layer serving as diffusion.

The prism sheet 6 is provided to increase the front luminance of light transmitted through and reflected on the diffusion plate 5. The prism sheet 6 allows only light having a specific angle to pass therethrough, The total internal reflection occurs and returns to the lower portion of the prism sheet 6 again. The light that is returned as described above is reflected by the reflector 4.

The backlight unit configured as described above is fixed to a mold frame, the liquid crystal panel 1 disposed on the backlight unit is protected by a top chassis, The frame is coupled while accommodating the backlight unit (Backlight Unit) and the liquid crystal panel 1 therebetween.

2 is a schematic cross-sectional view showing a conventional backlight unit of an edge type.

2, the conventional edge type backlight unit includes a fluorescent lamp 11 coated with a fluorescent material on the inner surface to emit light, and a fluorescent lamp 11 fixed from the fluorescent lamp 11 A light guide plate 13 for supplying the light emitted from the fluorescent lamp 11 to the liquid crystal panel side of the backlight and a light guide plate 13 attached to the lower portion of the light guide plate 13 A reflection plate 14 for reflecting the light leaking to the opposite side of the liquid crystal panel to the light guide plate 13 and a diffusion plate 15 for uniformly diffusing the light from the light guide plate 13 located above the light guide plate 13, A prism sheet 16 positioned above the diffuser plate 15 to condense the light diffused in the diffuser plate 15 and transmit the condensed light to the liquid crystal panel, 16, , It consists of a main support (18) that secure the housing to the component.

The edge method in which the lamp unit is installed on the side surface of the light guide plate 13 is applied to a liquid crystal display device of relatively small size such as a monitor of a laptop computer and a desktop computer , The uniformity of light is good, the durability life is long, and it is advantageous for thinning the liquid crystal display device.

However, the edge-type backlight unit described above is difficult to obtain a high-brightness backlight unit because of the limitation of the size and the capacity of the fluorescent lamp 11.

The edge method is a method in which the fluorescent lamp 11 is positioned on the side of the light guide plate 13 serving as the actual light emitting surface and the space of the side where the fluorescent lamp 11 is to be placed and the space of the fluorescent lamp 11 The upper and lower assembly spaces to be fastened to the backlight unit structure of the backlight unit are required, and the outer size of the backlight unit becomes large.

Such an edge type backlight unit may also be thinner than the direct-type structure, which is a method of regularly arranging the lamps under the diffusing plate. However, a separate component such as a lamp housing is required for constituting the lamp assembly, , There is a disadvantage that the size of the outside increases. .

Hereinafter, a direct-backlight type backlight unit in which the outer size is reduced as compared with the above-described backlight unit of the edge type will be described.

3 is a schematic cross-sectional view showing a backlight unit of a conventional direct type.

3, the conventional direct backlight unit includes a plurality of fluorescent lamps 21 arranged at regular intervals on the back surface of a liquid crystal panel (not shown), and a plurality of fluorescent lamps 21 A cover bottom 23 for supporting a reflecting plate 22 surrounding the fluorescent lamp 21 and a cover bottom 23 for covering the fluorescent lamp 21, And a diffusion sheet (24) formed on the upper portion to diffuse light generated in the fluorescent lamp (21) and a diffusion sheet (25) configured to disperse light emitted from the fluorescent lamp (21).

Here, the diffusion sheet 25 is made of a material such as polyethylene terephthalate (PET).

In the direct type system, a fluorescent lamp is arranged on a flat surface. Since the shape of the fluorescent lamp appears on the liquid crystal panel, the gap between the lamp and the liquid crystal panel must be maintained. In order to uniformly distribute the light amount, There is a limit. Also, as the panel becomes larger, the area of the light output surface of the backlight also increases. In the case of enlarging the direct-type backlight, if the light scattering means can not secure a sufficient thickness, the light output surface is not flat. The thickness of the light scattering means must be sufficiently secured.

The backlight unit of this direct type has started to be developed mainly as the size of the liquid crystal display device starts to become larger than 20 inches, and a plurality of lamps are arranged in a row on the lower surface of the diffusion plate, Direct dimming.

The direct-down scheme is mainly used for a large-screen liquid crystal display device which requires a high brightness because the utilization efficiency of light is higher than that of the edge scheme.

However, in the case of a direct-type liquid crystal display device, since it is used for a large-sized monitor or a television, it takes longer time to use than a laptop type computer and the number of lamps is large. The possibility of lamps that do not light up is more likely to occur.

In the direct type, a plurality of lamps are installed on the bottom of the screen. Therefore, when one lamp is not turned on due to the lamp life or failure, for example, the portion where the lamp is not lit is significantly darker than the other portions. Part will appear directly on the screen.

Therefore, since the lamp is frequently replaced in the direct-down system, the lamp unit must have an easy structure for disassembling and assembling the lamp unit.

As a conventional backlight unit system, there are the edge system and the direct-down system, which have the following problems.

In the case of the edge type lamp, since the lamp is positioned on the side, a lamp assembly having a structure for enclosing the lamp on the upper and lower outer sides of the light guide plate is required, a side space is required and the size of the backlight outside is increased. Therefore, the outline size versus the effective screen area efficiency is poor.

On the other hand, since the lamps are arranged at regular intervals under the diffusion plate, there is a problem in that the height is increased and the margin is required.

It is an object of the present invention to provide a backlight unit having a lamp array in a diffusion plate and omitting an assembly structure necessary for a lamp housing.

According to an aspect of the present invention, there is provided a backlight unit comprising: a diffusion plate having a plurality of holes spaced equidistantly from one side to the other; a plurality of lamps formed in the plurality of holes; And a cover bottom formed to surround the diffusion plate and the outer periphery of the reflection plate.

The diameter of the hole is formed to be relatively larger than the diameter of the lamp.

The lamp is provided with a silicon rubber for supporting the lamp at a predetermined position to keep the lamp separated from the hole.

The diffusion plate has a thickness larger than the diameter of the hole.

The diffusion plate includes a light diffusion material in PMMA (Poly Methyl Meta Acrylate) or PC (Poly Carbonate).

Hereinafter, the backlight unit of the present invention will be described in detail with reference to the accompanying drawings.

4 is a cross-sectional view of the backlight unit of the present invention, and Fig. 5 is an exploded perspective view of Fig.

As shown in FIG. 4, the backlight unit of the present invention includes a plurality of cylindrical lamps 41 spaced apart from each other with a hole 50 in a diffuser plate 42. A reflective plate 43 is wrapped around the rear surface of the diffusion plate 42 and covers the diffusion plate 42 and the reflection plate 43 including the plurality of lamps 41. [ bottom 44 are formed.

At this time, the hole 50 has a diameter relatively larger than the diameter of the lamp 41, and is pierced through a predetermined diameter from one side to the other side of the diffusion plate 42.                     

As the material of the diffusion plate 42, a transparent plate material such as glass or synthetic resin can be used. As the synthetic resin, various synthetic resins having high transparency such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polyolefin resin, polystyrene, or a copolymer of methyl methacrylate (MMA) and styrene (St) And the diffusion plate 42 can be manufactured by molding the resin into a plate by an ordinary molding method such as extrusion molding or injection molding.

In particular, a methacrylic resin such as polymethyl methacrylate (PMMA) has excellent light transmittance height, heat resistance, mechanical properties and molding processability, and is most suitable as a material for serving as a light guide plate as well as a diffusion plate Do. Such a methacrylic resin is a resin containing methyl methacrylate as a main component, and it is preferable that methyl methacrylate is 80% by weight or more.

Further, a light diffusing agent, fine particles, etc. may be mixed into the diffusion plate 42.

When the diffusion plate 42 is made of PMMA or a PC material, for example, the light diffusion material referred to here includes (a) silicon resin fine particles having an average particle diameter of 1 to 6 m and an inorganic transparent material powder (such as barium sulfate, calcium carbonate (b) an inorganic fine powder such as barium sulfate or calcium carbonate of 10 탆 or less, (c) a glass powder of 1 to 10 탆, an inorganic transparent material powder such as quartz powder or calcium fluoride, (D) transparent fine particles such as silica, glass, calcium fluoride (CaF 2) and aluminum hydroxide (Al (OH) 3) of 4 to 50 탆; And the like are dispersed in a resin of PMMA (Poly Methyl Methacrylate) or PC (Poly Carbonate).

As described above, when the diffusion plate 42 containing the obtained light diffusing agent is used, a sufficient diffusing sheet can be omitted in addition to the diffusion plate 42 because a sufficient luminance and a good luminance distribution of the light- have

The structure excluding the cover bottom 44 may be referred to as a lamp assembly. The lamp assembly and other similar companies may be assembled in an assembled state and supplied from a backlight maker or a similar company.

Since the lamp is formed inside the diffusion plate 42, the backlight unit of the present invention does not require a separate component such as a lamp housing for the lamp assembly, And the diffusion plate 42 are spaced apart from each other by a predetermined distance, the thickness can be reduced.

In the backlight unit of the present invention, the lamp is positioned below the liquid crystal panel. In the same manner as the direct-down type, the backlight unit of the present invention emits light from the lamp 41 through the reflection plate 43, The light is directed toward the liquid crystal panel, so that it is not necessary to construct a light guide plate for guiding the direction of light separately.

The backlight unit of the present invention is characterized in that the lamp unit 41 is provided inside the diffuser plate 42 in comparison with the point that a space is required in the upper and lower portions of the side of the light guide plate on which the lamp comes out owing to the lamp housing in which the edge system assembles the lamp ) Can be configured and integrated most.

Fig. 5 is an exploded perspective view showing the lamp and the silicon rubber supporting the lamp of Fig. 4;                     

5, the structure of the lamp 41 formed in the diffusion plate 42 may include a cylindrical tube having a predetermined diameter, or a lamp having a lamp 41 at a predetermined position of the lamp 41, 50 so as to be fixed thereto.

When the voltage is applied to the actual lamp 41, the voltage is applied to the portion where the voltage is applied, so that the loss of the diffusion plate around the lamp 41 may be a problem. Therefore, the backlight unit of the present invention does not fit the lamp 41 into the diffusion plate 42 but supports the lamp 41 in the hole 50 formed in the diffusion plate 42 So that the lamp 41 is not directly contacted with the diffusion plate 42. In this case, Thus, the problem that the diffusion plate 42 is damaged by the heat generated by the lamp is prevented.

FIG. 6 is an exploded perspective view showing a backlight unit having a plurality of lamps in the transparent diffusion plate of FIG. 5;

6, in the backlight unit of the present invention, a plurality of cylindrical lamps 41 are formed in a transparent diffusion plate 42 spaced apart from each other by a predetermined distance. In order to apply a voltage to each lamp 41 And a voltage applying line 51 is connected to one side and the other side through a hole 50. Each of the lamps 41 is provided with a silicone rubber 45 so as to maintain a predetermined gap therebetween in the hole 50.

The thickness of the diffusion plate 42 is determined according to the diameter of the lamp 41. That is, the diffusion plate 42 has a thickness larger than the diameter of the hole 50 because the inner hole 50 should be formed, and the hole 50 must be formed at a predetermined distance from the lamp 41, The diameter of the lamp (41) should be smaller than the diameter of the hole (50).

That is, if the diameter of the lamp 41 is smaller than that of the hole 50, for example, the diameter of the lamp is 2.4 mm, the hole 50 is manufactured with a diameter of 2.45 mm, 2.5 mm, In this case, the thickness of the diffusion plate 42 may be 3 mm or more, which is a margin somewhat larger than the diameter of the hole 50.

As described above, in the backlight unit of the present invention, when a lamp is formed in the diffusion plate 42, a lamp assembly structure is not required, and the reflection plate 43 and the cover bottom The size of the diffusion plate 42 is controlled by the thickness and the width of the diffusion plate 42.

Therefore, the outer size of the backlight unit is not increased, and the effective size of the outer size is effective. That is, since the lamp assembly can be assembled in a lamp assembly state, the productivity can be improved.

The backlight unit of the present invention as described above has the following effects.

First, since a separate lamp assembly structure is not required in a form in which a lamp is inserted into a diffusion plate, rather than an edge type in which the lamp is located on the side of the light guide plate or a direct type in which the lamp is located under the diffusion plate, And the thickness of the backlight unit itself can also be reduced.

Second, if the lamp assembly structure of the backlight unit is not required, the material cost can be reduced and the productivity can be improved.                     

Third, it is possible to increase the effective screen area in comparison with the conventional one in the same outer size.

Claims (5)

A plurality of holes extending from one side to the other side and spaced equidistantly from each other, A plurality of lamps each formed in the plurality of holes; A silicon rubber which supports each of the lamps and is located at a central portion of the lamps and keeps the lamps apart from the surface of the holes; A reflecting plate formed to surround the rear surface and the side surface except for the top surface of the diffuser plate; And And a cover bottom formed to surround the diffusion plate and the reflection plate so as to surround the diffusion plate and the reflection plate. delete delete The method according to claim 1, Wherein the diffuser plate has a thickness greater than the diameter of the hole. The method according to claim 1, Wherein the diffusion plate comprises a light diffusion material in PMMA (Poly Methyl Methacrylate) or PC (Poly Carbonate).

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