KR101212154B1 - backlight unit - Google Patents

Abstract

The present invention is to provide a backlight unit suitable for improving the overall appearance quality by helping to diffuse light into a corresponding dark area between the LED lamp, the backlight unit according to an embodiment for achieving the above object is to enter the side. A light guide plate having a light surface; And a plurality of LED lamps arranged at regular intervals so as to correspond to the light incidence surfaces of the light guide plate, wherein the surface of the light incidence surface in a region corresponding to the plurality of LED lamps is flat and corresponding to the plurality of LED lamps. A diffusion portion is formed on a surface of the light incident surface in the region to be formed, the diffusion portion is formed in a plurality of identical convex or concave patterns, and the plurality of identical convex or concave patterns have random roughness.

LED, diffuser, light incident surface, light guide plate

Description

Backlight unit

1 is a perspective view of a backlight unit having a conventional LED

2 is a plan view of a backlight unit using a conventional LED

3 is a plan view showing light distribution when driving a conventional backlight unit;

4 is a perspective view of a backlight unit according to a first embodiment of the present invention;

5 is a plan view of a backlight unit according to a first embodiment of the present invention;

6 is a plan view showing light distribution when driving the backlight unit according to the first embodiment of the present invention;

7 is a perspective view of a backlight unit according to a second embodiment of the present invention;

8 is a plan view of a backlight unit according to a second embodiment of the present invention;

9 is a plan view showing light distribution when driving the backlight unit according to the second embodiment of the present invention;

10 is a perspective view of a backlight unit according to a third embodiment of the present invention;

11A to 11C are exemplary views illustrating the shape of diffusion parts on upper and lower surfaces of the light guide plate.

Explanation of symbols on the main parts of the drawings

40, 70: Light guide plate 41, 71, 71a: Diffusion part

42, 72: LED lamp 43, 73: light scattering means

46, 76: reflector 47, 77: PCB board

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit suitable for improving appearance quality by solving a dark phenomenon in a region between LED lamps, in particular, where light corresponds to a relatively dark region.

CRT (Cathode Ray Tube), one of the commonly used display devices, is mainly used for monitors such as TVs, measuring devices, information terminal devices, etc., but the miniaturization of electronic products due to the weight and size of CRT itself It was unable to actively respond to 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. Liquid crystal display (LCD) and gas discharge using electro-optic effects Plasma Display Panel (PDP) and Electro Luminescence Display (ELD) using the electroluminescent effect, among others, are being actively studied for the liquid crystal display device.

In order to replace the CRT, a liquid crystal display device having advantages such as small size, light weight, and low power consumption has recently been developed to be able to perform a sufficient role as a flat panel display device. As used in monitors and large information display devices, the demand for liquid crystal display devices continues to increase.

The liquid crystal display may be classified into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel. The liquid crystal panel may include first and second glass substrates bonded to each other with a predetermined space, and It consists of the liquid crystal layer injected between the 1st, 2nd glass substrate.

The first glass substrate (TFT array substrate) may include a plurality of gate lines arranged in one direction at a predetermined interval, 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 crossing a gate line and a data line, and a plurality of thin films which are switched by signals of the gate line to transfer the signal of the data line to each pixel electrode Transistors are formed.

The second glass substrate (color filter substrate) includes a black matrix layer for blocking light in portions other than the pixel region, an R, G and B color filter layer for expressing color colors, and a common electrode for implementing an image. Is formed.

The first and second glass substrates are bonded to each other by a seal material having a predetermined space by a spacer and having a liquid crystal injection hole, so that the liquid crystal is injected between the two substrates.

On the other hand, since most of the liquid crystal display devices are light-receiving elements that display an image by controlling the amount of light source coming from the outside, a separate light source, that is, a backlight unit, for irradiating light to the liquid crystal panel is necessary. The light unit is divided into an edge method and a direct method according to the location where the lamp unit is installed.

The light source may be an EL (Electro Luminescence), an LED (Light Emitting Diode), a CCFL (Cold Cathode Fluorescent Lamp), a HCFL (Hot Cathode Fluorescent Lamp), an external electrode light emitting lamp (EEFL) and the like.

In the above, CCFL, HCFL, and EEFL are used to represent line light sources and surface light sources, and LEDs can be used to represent point light sources.

In addition, the backlight unit has been used as a function for reading information displayed on the screen of the liquid crystal display in a dark place, but recently, the light guide plate has been formed thinner due to various requirements such as design, low power consumption, and thinning. In addition to a function capable of expressing various colors, technology development for reducing power consumption by using the LED (Light Emitting Diode) has been made.

The LED is a solid-state device using a photoelectric conversion effect of a semiconductor, a semiconductor device that emits light when a forward voltage is applied, and emits light at a lower voltage than a lamp using tungsten filament, the filament is not heated and shining, but electrons recombine with holes Since it emits light due to the difference in energy, it has been widely used in various display devices for a long time.

By using the LED as a light source for illuminating the liquid crystal panel, it is possible to easily achieve low power consumption and miniaturization of electronic devices such as a notebook PC.

In addition, since a DC voltage of about V is required to emit LEDs, a DA-AC converter is not required, so the driving device is simple and power consumption can be significantly reduced.

Moreover, since LED is a semiconductor element, it is more reliable than a cathode ray tube, and is small and long life.

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

1 is a perspective view illustrating a backlight unit using a conventional LED, FIG. 2 is a plan view of a backlight unit using a conventional LED, and FIG. 3 is a plan view illustrating light distribution when driving the conventional backlight unit.

In the conventional backlight unit having LEDs, as illustrated in FIGS. 1 and 2, a light guide plate 20 formed on the rear surface of the liquid crystal panel 10 and a plurality of LED lamps 21 on one side of the light guide plate 20 are provided. LED light source and a reflector 22 disposed on the lower surface of the light guide plate 20.

Although not shown in the figure, a lamp housing having reflective characteristics is further provided to surround the LED lamps 21 as a whole.

As described above, the LED light source is composed of a plurality of LED lamps 21 arranged in one dimension, wherein the LED lamps 21 sequentially red LED, green LED, blue LED on the PCB substrate It may be arranged, or may be arranged in white LEDs.

When the backlight unit configured as described above implements an image on the liquid crystal panel 10, each of the LED lamps 21 constituting the LED light source is turned on, and the light generated by the LED lamp 21 is light guide plate 20. Scattered within the beam) and transferred to the rear surface of the liquid crystal panel 10.

In this case, when the LED lamps 21 emit light (ON state), as shown in FIG. 3, light is not uniformly transmitted between the LED lamps 21. That is, a strong light is transmitted to the portion where the LED lamp 21 is located, and a phenomenon in which light is not transmitted well occurs.

Reference numeral '23' is a PCB board on which an LED lamp is mounted.

The conventional backlight unit configured as described above has the following problems.

As described above, since the LED lamps 21 are point light sources, the uniformity of the light distribution irradiated onto the liquid crystal panel is inferior to that of the CCFL or EEFL which is the linear light source.

In particular, since the LED lamp is a point light source in which light propagation to the left and the right is unfavorable, strong light is transmitted from the light incident plate adjacent to the portion where the LED lamp 21 is located, and light is transmitted to other parts. It doesn't work so well that dark areas occur. This causes a problem of poor appearance of the backlight unit.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a backlight unit suitable for improving the overall appearance quality by helping to diffuse light into the corresponding dark areas between the LED lamps.

According to an aspect of the present invention, there is provided a backlight unit including: a light guide plate having a plurality of diffusion parts in a region corresponding to a portion where light is dark on at least one light incident surface; It characterized in that it comprises a plurality of LED lamps arranged at a predetermined interval on at least one side of the light guide plate.

According to another embodiment of the present invention, a backlight unit includes: a light guide plate having a plurality of diffusion parts on an upper surface or a lower surface of a light incident surface corresponding to a portion where light is dark; It characterized in that it comprises a plurality of LED lamps arranged at a predetermined interval on at least one side of the light guide plate.

The light guide plate may be a prism light guide plate having a prism acid formed on a lower surface thereof.

The diffusion part formed in the light guide plate may be configured to be formed in a portion corresponding to the LED lamps.

The diffusion portion formed in the light guide plate is configured to have a plurality of convex or concave shapes and random roughness, and the shape of the diffusion portion is regular or irregular.

The backlight unit may further include a reflecting plate on a lower surface of the light guide plate, a lamp housing surrounding the LED lamp as a whole, a PCB substrate supporting the LED lamp, and light scattering means on an upper surface of the light guide plate.

The light scattering means is characterized by consisting of a plurality of diffusion sheet (Diffusion sheet), a diffusion plate (Diffusion plate) and a prism sheet.

The diffusion part of the upper surface or the lower surface of the light guide plate may be formed in various shapes such as a rectangular shape, a semi-circle, or a similar half part of a round shape, a circle, or an oval.

Hereinafter, a backlight unit according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

First Embodiment

4 is a perspective view of a backlight unit according to a first embodiment of the present invention, FIG. 5 is a plan view of a backlight unit according to a first embodiment of the present invention, and FIG. 6 is a backlight unit according to a first embodiment of the present invention. A plan view showing the light distribution during driving.

As shown in FIGS. 4 and 5, the backlight unit according to the first embodiment of the present invention includes a light guide plate 40 having a plurality of diffusion parts 41 which guide light and are spaced apart from a light incident surface. A plurality of LED lamps 42 arranged at a predetermined interval on the light incident surface side of the light guide plate 40, light scattering means 43 provided on the top surface of the light guide plate 40, and a bottom surface of the light guide plate 40. It is comprised including the reflecting plate 46 comprised.

The reflecting plate 46 is provided to maximize the light utilization efficiency by intensively irradiating the light generated by the LED lamp 42 to the display unit of the liquid crystal panel (not shown).

The light guide plate 40 is composed of a prism light guide plate, and the prism light guide plate has a prism acid formed on the lower surface of the light guide plate, so that the light has a good linearity, and the light guide plate 40 is easily formed to straighten the light from the light incident portion. Since the prism acid at the bottom of the prism light guide plate is in the form of an inverted triangle, the straightness of the light is good, thereby advantageously achieving high luminance.

The diffusion part 41 formed on the light incident surface of the light guide plate 40 is configured at a portion corresponding to the LED lamps 42 or a portion where the light is relatively dark. Usually, the portion where the LED lamp 42 is not disposed (the portion that does not face the LED lamp) is formed in this portion because it looks dark because no concentration of light occurs.

The diffusion part 41 formed on the light incident surface of the light guide plate 40 corresponding to the dark portion formed as described above causes the light generated by the LED lamp 42 to spread to the dark areas between the LED lamps 42, thereby forming a dark area. It serves to compensate.

In detail, the LED lamp 42 is used as a point light source, and exhibits a hot spot characteristic in a region where light is generated. That is, the peripheral area appears relatively dark due to the phenomenon that the LED lamp 42 portion is brighter than the peripheral area, so that when viewed from the light incident surface side of the light guide plate 40, the dark phenomenon occurs in the light receiving area between the LED lamps 42. This happens.

In order to solve such a problem, the present invention is to form the diffusion part 41 on the light incident surface of the light guide plate 40 corresponding to a region where the light is relatively dark, in particular, the region between the LED lamps 42. That is, light is diffused through the diffusion part 41 formed on the light incident surface of the light guide plate 40 so that the dark area is compensated for.

As such, the dark region between the LED lamps 42 is reinforced by the light diffused by the diffusion part 41 formed on the light incident surface of the light guide plate 40, so that the light incident region of the light guide plate 40 is shown in FIG. 6. May represent a uniform luminance as a whole.

The diffusion part 41 formed on the light incident surface of the light guide plate 40 may be configured to have a plurality of convex or concave shapes and random roughness. In addition, the shape of the diffusion portion 41 may be regular or irregular.

Although not shown in the drawings, the diffusion part 41 may be formed by a mold injection method when forming the light guide plate 40, or may be formed by applying a physical force from the outside to give a scratch, or may form a pattern using a laser. Can be.

The diffusion portion 41 for diffusion formed on the light incident surface of the light guide plate 40 is convex or concave and its roughness is small (weak). However, even if the roughness is small as described above, since the light guide plate 40 is formed of a prism light guide plate with easy straightness of light, light can be made to spread through the diffuser to make the light incident region have a uniform luminance.

The light scattering means 43 is a plurality of diffusion sheets (Diffusion) on the upper surface of the light guide plate 40 in order to provide a light source having a uniform distribution of brightness as a whole light generated from the LED lamp 42 on the display surface of the liquid crystal panel sheet, diffusion plate and prism sheet.

In addition, although not shown in the drawing, the backlight unit having the above configuration further includes a lamp housing to surround the LED lamp 42 as a whole, and the lamp housing includes light guide plate 40 in which light generated from the LED lamp 42 is disposed. It is made of reflective material so that it can be delivered to the light-receiving surface.

Reference numeral 47 denotes a PCB substrate for supporting the LED lamp 42.

In the above description, the edge type backlight unit in which the LED lamps are arranged on one side of the light guide plate is described, but the LED lamps are arranged on both sides of the light guide plate, and the light incident surfaces on both sides of the light guide plate correspond to relatively dark areas between the LED lamps. It may be formed to have a plurality of diffusions 41 in the.

The edge type backlight unit configured as described above condenses the light emitted from the LED lamp 42 to the light incident surface of the light guide plate 40, and then sequentially passes through the light scattering means 43 through the light guide plate 40 to the liquid crystal panel. To pass.

As in the first embodiment of the present invention, when the diffusion part 41 is formed on the light incident surface of the light guide plate 40 in a relatively dark area, in particular, between the LED lamps, the light incident surface of the light guide plate 40 The light spreads through the diffusion portion 41 to the light incident region where the LED lamp 42 is not located, so that the hot spot region is alleviated. As a result, the light incident region can exhibit uniform light emission characteristics as a whole.

Meanwhile, the backlight unit of the present invention may be used as a light source at the rear or front of various display devices including a liquid crystal display device, and may be used as a light emitting device as it is.

Second Embodiment

7 is a perspective view of a backlight unit according to a second embodiment of the present invention, FIG. 8 is a plan view of a backlight unit according to a second embodiment of the present invention, and FIG. 9 is a backlight unit according to a second embodiment of the present invention. A plan view showing the light distribution during driving.

11A to 11C are exemplary views illustrating various shapes of diffusion parts on upper and lower surfaces of the light guide plate.

As shown in FIGS. 7 and 8, the backlight unit according to the second embodiment of the present invention includes a light guide plate 70 having a plurality of diffusion parts 71 formed to guide light and spaced apart from an upper surface thereof. A plurality of LED lamps 72 arranged at one side of the light guide plate 70 at a predetermined interval, the light scattering means 73 provided on the light guide plate 70 and the lower portion of the light guide plate 70 It is comprised including the reflecting plate 76 comprised.

The reflector 76 is provided to maximize the light utilization efficiency by intensively irradiating the light generated from the LED lamp 72 to the display unit of the liquid crystal panel (not shown).

The light guide plate 70 is composed of a prism light guide plate, and the prism light guide plate is formed with a prism acid on the lower surface of the light guide plate itself, so that the light is straight, and the light is easily formed to move straight from the light incident part.

The diffusion part 71 formed on the upper surface of the light guide plate 70 is configured at a portion corresponding to the LED lamps 72 and a portion where the light is relatively dark. Usually, the portion where the LED lamp 72 is not disposed (the portion that does not face the LED lamp) is formed in this portion because it looks dark because no concentration of light occurs.

The diffusion part 71 formed on the upper surface of the light guide plate 70 corresponding to the dark portion formed as described above is the LED lamp 72 when the light generated from the LED lamp 72 is transferred to the upper side through the light guide plate 70. Helps diffuse into the dark areas between) to compensate for dark areas.

In detail, the LED lamp 72 is used as a point light source, and exhibits a hot spot characteristic in a region where light is generated. That is, since the portion of the LED lamp 72 emits light brighter than the surrounding area, when viewed from above the light receiving area of the light guide plate 70, the light receiving area upper part corresponding to the LED lamps 72 appears relatively dark.

In order to solve this problem, the present invention is to form a diffusion portion 71 on the upper surface of the light guide plate 70 corresponding to a region where the light is relatively dark, in particular, the region between the LED lamp 72. That is, light is diffused into the dark region between the LED lamps 72 through the diffuser 71 formed on the upper surface of the light guide plate 70 so that the dark region is compensated for.

As shown in FIG. 9, a relatively dark area due to the hot spot characteristic of the LED lamp 72 is diffused and reinforced by the diffuser 71 formed on the upper surface of the light guide plate 70. The light incident region around the light guide plate 70 may exhibit uniform luminance as a whole.

The diffusion part 71 formed on the upper surface of the light guide plate 70 may be configured to have a plurality of convex or concave shapes and random roughness. In addition, the shape of the diffusion portion 71 may be regular or irregular.

Although not shown in the drawing, the diffusion part 71 may be formed by a mold injection method when forming the light guide plate 70, may be formed by applying a physical force from the outside, or may be patterned using a laser. Can be.

The diffusion portion 71 formed on the upper surface of the light guide plate 70 has a convex or concave shape and a roughness thereof is small.

11A to 11C, the diffusion portion 71 of the upper surface of the light guide plate 70 may be formed in various shapes such as a rectangular shape, a semicircle, or a similar half portion having a round shape, a circle, or an ellipse. Can be.

The light scattering means 73 is a plurality of diffusion sheets (Diffusion) on the upper surface of the light guide plate 70 in order to provide a light source having a uniform brightness distribution on the display surface of the liquid crystal panel, the light generated from the LED lamp 72 sheet, diffusion plate and prism sheet.

Although the backlight unit having the above configuration is not shown in the drawing, the lamp housing further includes a lamp housing so as to surround the LED lamp 72 as a whole, wherein the light generated from the LED lamp 72 is formed by the light guide plate 70. It is made of reflective material so that it can be delivered to the light-receiving surface.

Reference numeral 77 denotes a PCB substrate for supporting the LED lamp 72.

In the above description, the edge type backlight unit in which the LED lamps are arranged on one side of the LGP is described, but the LED lamps are arranged on both sides of the LGP, and the upper surfaces of both sides of the LGP corresponding to the relatively dark areas between the LED lamps. It may be formed to have a plurality of diffusion portions 71 in the.

The edge type backlight unit configured as described above condenses the light emitted from the LED lamp 72 to the light incident surface of the light guide plate 70, and then sequentially passes through the light scattering means 73 through the light guide plate 70 to the liquid crystal panel. To pass.

As described above, in the backlight unit according to the second embodiment of the present invention, when the diffusion part 71 is formed on the upper surface of the light guide plate 70 in a region corresponding to a relatively dark area, particularly between LED lamps, the light guide plate ( Light is diffused to the region where the LED lamp 72 is not located through the diffusion portion 71 of the upper surface of the 70, so that the hot spot characteristic is alleviated. As a result, the light incident region can exhibit uniform light emission characteristics as a whole.

Meanwhile, the backlight unit of the present invention may be used as a light source at the rear or front of various display devices including a liquid crystal display device, and may be used as a light emitting device as it is.

Third Embodiment

FIG. 10 is a perspective view of a backlight unit according to a third embodiment of the present invention, and FIGS. 11A to 11C are exemplary views showing various shapes of diffusion parts on upper and lower surfaces of the light guide plate.

The third embodiment of the present invention is the second embodiment of the present invention except that the diffusion portion 71a is partially and regularly formed between the LED lamps 72 and the lower surface of the light guide plate 71 corresponding to the dark area. The same as the configuration according to the following will be omitted.

10 is shown and shown in the same manner as in the second embodiment of the present invention except for the diffuser 71a formed on the lower surface of the light guide plate.

The diffusion portion 71a formed on the lower surface of the light guide plate 70 corresponding to the dark portion as described above is lighted to the dark region between the LED lamp 72 when the light guide plate 70 receives light from the LED lamp 72. Diffusion is used to compensate for dark areas.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention.

Accordingly, the technical scope of the present invention should not be limited to the contents described in the above embodiments, but should be determined by the claims.

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

By forming a diffusion part in a relatively dark area, in particular, the light receiving surface or the upper and lower surfaces of the light guide plate corresponding to the LED lamps, the light can be diffused between the LED lamps so as to exhibit uniform light emission characteristics as a whole. Can improve the appearance quality.

Claims (8)

A light guide plate having a light incident surface on its side; And It includes a plurality of LED lamps are arranged at a predetermined interval so as to correspond to the light incident surface of the light guide plate, The surface of the light incident surface of the region corresponding to the plurality of LED lamps is flat, and a diffusion portion is formed on the surface of the light incident surface of the region corresponding to the plurality of LED lamps, And the diffusion portion is formed in a plurality of identical convex or concave patterns, and the plurality of identical convex or concave patterns have a random roughness. delete The method of claim 1, And the light guide plate is a prism light guide plate having a prism acid formed on a lower surface thereof. delete delete The method of claim 1, The backlight unit may include a reflector on a bottom surface of the light guide plate, A lamp housing surrounding the LED lamp as a whole; A PCB substrate supporting the LED lamp; The light scattering unit is further provided on the upper surface of the light guide plate. The method of claim 6, The light scattering means is a backlight unit, characterized in that consisting of a plurality of diffusion sheet (Diffusion sheet), a diffusion plate (Diffusion plate) and a prism sheet. delete

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