KR101232143B1 - backlight unit - Google Patents

Abstract

The present invention is to provide a backlight unit suitable for improving the appearance quality by minimizing the darkness in the light incident region between the LED lamp, the backlight unit for achieving the above object comprises a light guide plate configured on the cover bottom; A plurality of LED lamps arranged at a predetermined interval on at least one side of the light guide plate; Light scattering means provided on an upper surface of the light guide plate; And a light diffusing structure attached to at least a daily surface of the light guide plate corresponding to the LED lamp.

Light diffusion structure, LED, light receiving area, light guide plate, light scattering means

Description

Backlight unit

1 is a perspective view showing a backlight unit using a conventional LED

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

3A and 3B are plan views illustrating light distribution when driving a conventional backlight unit.

4 is a plan view of a backlight unit according to an exemplary embodiment of the present invention.

5 is a structural cross-sectional view of the backlight unit according to the first embodiment of the present invention.

6 is a structural cross-sectional view of the backlight unit according to the second embodiment of the present invention.

7 is a plan view showing a light distribution when driving the backlight unit according to the present invention;

Explanation of symbols on the main parts of the drawings

41: light guide plate 42: LED lamp

43: light scattering means 45: light diffusion structure

46: reflector 47: PCB substrate

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 solving a dark phenomenon in a light incident region corresponding to an LED lamp.

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.

Here, the first glass substrate (TFT array substrate) includes 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, and A plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing each of the gate lines and the data lines, and a plurality of pixels which are switched by signals of the gate lines to transfer signals of the data lines to the pixel electrodes Thin film 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 for illuminating the liquid crystal panel, that is, a backlight unit, is necessary. The unit is divided into the edge method and the direct method according to the position 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.

In addition, when the backlight unit is configured using the CCFL and the EEFL, the color reproducibility is low due to the light emission characteristics of the light source itself. In addition, it is difficult to obtain a high brightness backlight unit due to constraints of the size and capacity of the fluorescent lamp.

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

1 is a cross-sectional view showing a backlight unit using a conventional LED, Figure 2 is a plan view of a backlight unit using a conventional LED.

3A and 3B are plan views illustrating light distribution when driving a 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. Scattering therein is transmitted to the back of the liquid crystal panel 10.

At this time, when the LED lamps 21 do not emit light (OFF state) as shown in Figure 3a, when the LED lamps 21 emits light (ON state), as shown in Figure 3b, the LED lamps 21 There is a phenomenon that no light is transmitted between them.

Reference numeral '23' is a PCB substrate on which the LED lamp is mounted, and '24' is a light scattering means.

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, a dark region is generated by the interval between the LED lamps 21 in the light receiving region of the light guide plate.

The present invention has been made to solve the above problems, it is an object of the present invention to provide a backlight unit suitable for improving the appearance quality by minimizing the darkness in the light incident region between the LED lamp.

A backlight unit according to an embodiment of the present invention for achieving the above object is a light guide plate configured on the cover bottom; A plurality of LED lamps arranged at a predetermined interval on at least one side of the light guide plate; Light scattering means provided on an upper surface of the light guide plate; And a light diffusing structure attached to at least a daily surface of the light guide plate corresponding to the LED lamp.

In another embodiment, a backlight unit includes: a light guide plate configured on a cover bottom; A plurality of LED lamps arranged at a predetermined interval on at least one side of the light guide plate; Light scattering means provided on an upper surface of the light guide plate; The LED lamp corresponds to the arrangement, characterized in that it comprises a light diffusion structure attached to the upper portion of the light scattering means corresponding to the light incident region of at least one side of the light guide plate.

The light diffusion structure is characterized by consisting of any one of a diffusion material of PET, acrylic material, rubber (rubber) material, beads (beads).

The light diffusing structure is further characterized in that it is configured in a sheet form to be detachable.

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 backlight unit may further include a reflector on a lower surface of the light guide plate, a lamp housing surrounding the LED lamp as a whole, and a PCB substrate supporting the LED lamp.

The light diffusing structure is attached to any one layer of the diffusion sheet (Diffusion sheet), the diffusion plate (Diffusion plate) and the prism sheet, characterized in that formed.

In general, when a light emitting diode (LED) is used as a light source for illuminating a liquid crystal panel, it is possible to easily achieve small power consumption and miniaturization of electronic devices such as a notebook PC.

In addition, LED is a solid-state device using a photoelectric conversion effect of a semiconductor, and since a DC voltage of about 1.5V is applied to emit light of the LED, a DA-AC converter is not required, and power consumption can be greatly reduced.

In addition, since LEDs are semiconductor devices, they are more reliable than cathode ray tubes, and are small in size and long in life.

Hereinafter, in the present invention, when using the LED having the above advantages as a light emitting source, a look at the configuration that can exhibit a more uniform light emission characteristics as a whole.

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

First Embodiment

4 is a plan view of a backlight unit according to an embodiment of the present invention, Figure 5 is a cross-sectional view of the structure of the backlight unit according to a first embodiment of the present invention, Figure 7 is a light distribution when driving the backlight unit according to the present invention It is the top view shown.

As shown in FIGS. 4 and 5, the backlight unit according to the first embodiment of the present invention includes a light guide plate 41 having a predetermined thickness and formed in a rectangular shape to guide light on a cover bottom (not shown). And a plurality of LED lamps 42 arranged at a predetermined interval on one side of the light guide plate 41 at a predetermined interval, light scattering means 43 provided on an upper surface of the light guide plate 41, and the LED lamp ( And a light diffusing structure 45 attached to an upper surface of the light guide plate 41 corresponding to 42.

The lower surface of the light guide plate 41 is further provided with a reflecting plate 46 (see FIG. 5).

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 diffusion structure 45 is composed of any one of a diffusion material of PET, acrylic material, rubber material, beads (beads), a transparent adhesive after the roll processing the diffusion material (roll) Is attached to the light guide plate 41. At this time, the light diffusion structure 45 may be configured in a sheet form to be detachable.

The light diffusion structure 45 is attached to the light incident surface of the light guide plate 41 on which the LED lamp 42 is disposed, and serves to diffuse (disperse) light generated from the LED lamp 42 to the surrounding area.

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 portion of the LED lamp 42 is brighter than the peripheral area, so that when viewed from the light incident surface side of the light guide plate 41, the dark phenomenon occurs in the light receiving area between the LED lamps 42. This happens.

The present invention solves this problem by attaching the light diffusing structure 45 to the upper part of the light guide plate 41 corresponding to the LED lamp 42. In other words, the light diffusion structure 45 is attached to the light incident surface of the light guide plate 41 to attenuate the light in the light incident region of the LED lamp 42 to match the degree of brightness with the peripheral region.

The light scattering means 43 is a plurality of diffusion sheets (Diffusion) on the upper surface of the light guide plate 41 in order to provide a light source having a uniform distribution of brightness as a whole light emitted from the LED lamp 42 on the display surface of the liquid crystal panel sheet, diffusion plate and prism sheet.

Although not shown in the drawing, the backlight unit further includes a lamp housing to surround the LED lamp 42 as a whole, wherein the light generated from the LED lamp 42 is incident on the light incident surface of the light guide plate 41. It is made of reflective material so that it can be delivered completely.

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 diffusion structure is disposed on the light receiving area on both sides of the light guide plate corresponding to the LED lamp. It can also be attached.

As shown in FIG. 7, when the light diffusing structure 45 is attached to the light incident region of the light guide plate 41 as in the first embodiment of the present invention, the LED lamp 42 is It can be seen that the concentration of light is alleviated in the light incident region located. That is, it can be seen that the light incident region exhibits uniform light emission characteristics as a whole.

Second Embodiment

4 is a plan view of a backlight unit according to an embodiment of the present invention, Figure 6 is a cross-sectional view of the structure of the backlight unit according to a second embodiment of the present invention, Figure 7 is a light distribution when driving the backlight unit according to the present invention It is the top view shown.

As shown in FIGS. 4 and 6, the backlight unit according to the second embodiment of the present invention includes a light guide plate 41 having a predetermined thickness and configured in a rectangular shape to guide light on a cover bottom (not shown). In addition, a plurality of LED lamps 42 arranged at a predetermined interval on one side of the light guide plate 41 at a predetermined interval, and a plurality of diffusion sheets 43a and a diffusion plate on the upper surface of the light guide plate 41. A light scattering means 43 composed of a diffusion plate 43b and a prism sheet 43c, and a light diffusing structure 45 attached to an upper surface of the light scattering means 43 corresponding to the LED lamp 42. It is configured to include).

The lower surface of the light guide plate 41 is further provided with a reflecting plate 46 (see FIG. 6). 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 diffusion structure 45 is composed of a diffusion material including a PET material, an acrylic material, a rubber material, beads, and after the roll processing the diffusion material using a transparent adhesive To be attached to the light scattering means 43. At this time, the light diffusion structure 45 may be configured in a sheet form to be detachable.

As described above, the light diffusing structure 45 is attached to the light incident surface of the light scattering means 43 corresponding to the region where the LED lamp 42 is disposed, and diffuses the light generated by the LED lamp 42 to the surrounding area. It plays a role of (dispersion).

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 portion of the LED lamp 42 is brighter than the peripheral area, so that when viewed from the light incident surface side of the light guide plate 41, the dark phenomenon occurs in the light incident surfaces between the LED lamps 42. This happens.

The present invention solves this problem by attaching the light diffusing structure 45 to the upper portion of the light scattering means 43 corresponding to the LED lamp 42. In other words, the light diffusing structure 45 is attached to the upper portion corresponding to the light incidence area of the light guide plate 41 of the light scattering means 43 to attenuate the light in the light incidence area of the LED lamp 42 and thus the brightness of the light diffusing structure 45. It is to play a role.

In the light diffusing structure 45, the upper portion of any one of a plurality of diffusion sheets 43a, a diffusion plate 43b, and a prism sheet 43c constituting the light scattering means 43. Can be attached to

Although not shown in the drawing, the backlight unit further includes a lamp housing to surround the LED lamp 42 as a whole, wherein the light generated from the LED lamp 42 is incident on the light incident surface of the light guide plate 41. It is made of reflective material so that it can be delivered completely.

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

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 41, and then sequentially passes through the light diffusion plate 43 through the light diffusion plate 43 to the liquid crystal panel. To pass.

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 correspond to the portion where the LED lamps are arranged. The light diffusing structure may be attached to the upper portion of the corresponding light scattering means.

As shown in FIG. 7, the light distribution when the light diffusing structure 45 is attached to the upper portion of the light scattering means 43 corresponding to the light incidence region as in the second embodiment of the present invention is illustrated in FIG. 7. It can be seen that the phenomenon of concentration of light is alleviated in the incident region where the lamp 42 is located. That is, it can be seen that the light incident region exhibits uniform light emission characteristics as a whole.

On the other hand, such embodiments of the present invention can be used as a light source at the rear or front of various display devices, including a liquid crystal display device, as well as a light emitting device itself.

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.

Attaching the light diffusing structure to the light incident region of the light guide plate or the light scattering means reduces the concentration of light in the light incident region where the LED lamp is located (reducing the dark region between the LEDs), resulting in an overall uniform light emission characteristic. . Therefore, the appearance quality of the backlight unit can be improved.

Claims (7)

delete A light guide plate configured on the cover bottom; A plurality of LED lamps arranged at a predetermined interval on at least one side of the light guide plate; Light scattering means composed of a plurality of diffusion sheets, a diffusion plate, and a prism sheet provided on an upper surface of the light guide plate; A light diffusion structure attached to one of the diffusion sheet, the diffusion plate, and the prism sheet corresponding to the LED lamp to diffuse light generated by the LED lamp to a peripheral region; and; A reflection plate disposed 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 diffusion structure is formed of a detachable sheet formed of any one of a diffusion material of PET, acrylic, rubber, beads, and the like, and has a semicircular cross section corresponding to the LED lamp. Backlight unit having a. delete delete delete delete delete

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