KR20080003037A - Backlight unit - Google Patents

Abstract

A backlight unit is provided to suppress the occurrence of a darkness phenomenon between LED(Light Emitting Diode) lamps and thus improve exterior quality of the backlight unit by forming a groove in an upper surface or a lower surface of a light guide plate adjacent to the light incidence region between the LED lamps. A plurality of LED lamps(42) are configured at one side or both sides of a light guide plate(40). A groove(40a) is formed in an upper surface of the light guide plate adjacent to a light incidence surface between the LED lamps. The groove is rounded or has the other shape. The groove of the light guide panel is tapered away from the light incidence surface. The groove is further configured in a lower surface adjacent to a light incidence surface between the LED lamps. The backlight unit includes a reflective plate(43) under the light guide plate, a PCB(Printed Circuit Board)(41) supporting the LED lamp, and a light scattering unit(44) on the light guide plate.

Description

Backlight unit

1 is a perspective view showing a backlight unit using a conventional LED (see KP05-3064).

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

5 is an exemplary view showing the principle of refraction of incident light for explaining the present invention

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

Explanation of symbols on the main parts of the drawings

40: Light guide plate 40a, 40b: groove

41 PCB substrate 42 LED lamp

43: reflector 44: light scattering means

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.

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 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.

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, and thus a driving device is simple and power consumption can be greatly 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 having an LED 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.

First, since the LED lamp 21 is a point light source, the uniformity of the light distribution irradiated onto the liquid crystal panel is inferior to that of the CCFL or EEFL, which is a linear light source.

Secondly, the LED lamp is limited to approximately 110 degrees of emission angle, light propagation to the left and right is disadvantageous, and is a discontinuous point light source. Therefore, a dark region is generated in the light incident region of the light guide plate between the LED lamps 21. 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 solving the dark phenomenon in the light incident region corresponding to the LED lamp.

The backlight unit according to an embodiment of the present invention for achieving the above object, the light guide plate, a plurality of LED lamps configured on one side or both sides of the light guide plate, and the light adjacent to the light incident surface corresponding to the LED lamps It comprises a groove formed in the upper surface of the light guide plate.

The groove is characterized in that it is configured in a round (round) form or any other form.

The groove of the light guide plate is configured to start at the light incident surface and gradually decrease its width as it moves away from the light incident surface.

The groove further includes a lower surface adjacent to a light incident surface corresponding to the LED lamps.

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

The light scattering means comprises a plurality of diffusion sheets, diffusion plates, and prism sheets.

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

It will be described as follows.

4 is a perspective view of a structure of a backlight unit according to a first exemplary embodiment of the present invention, and FIG. 5 is an exemplary view showing a refraction principle of incident light for explaining the present invention.

First, the configuration of the backlight unit according to the first embodiment of the present invention will be described.

As shown in FIG. 4, the backlight unit according to the first embodiment of the present invention includes a light guide plate 40 having grooves 40a formed at regular intervals on an upper surface adjacent to a light incident surface on a rear surface of a liquid crystal panel (not shown). And a plurality of LED lamps 42 formed on one or both sides of the light guide plate 40, a PCB substrate 41 on which the LED lamps 42 are arranged, and a reflecting plate disposed on a bottom surface of the light guide plate 40. 43).

The reflecting plate 43 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).

In addition, a light scattering means 44 composed of a plurality of diffusion sheets, a diffusion plate, and a prism sheet is further provided on the light guide plate 40.

Although not shown in the drawings, the lamp housing further includes a lamp housing that completely surrounds the LED lamps 42 and has reflection characteristics therein.

In the above, the groove 40a of the light guide plate 40 is formed in the upper surface of the light guide plate 40 corresponding to the LED lamps 42. The width of the light guide plate 40 gradually decreases as it starts from the light incident surface and moves away from the light incident surface. It is configured to. In addition, the groove 40a may be configured as a round shape or another type of groove.

The LED light source is composed of a plurality of LED lamps 42 arranged in one dimension, wherein the LED lamps 42 are to sequentially arrange the red LED, green LED, blue LED on the PCB substrate 41 It may be arranged in white LEDs.

When the backlight unit configured as described above implements an image on the liquid crystal panel, each of the LED lamps 42 constituting the LED light source is turned on, and the light generated by the LED lamp 42 is scattered in the light guide plate 40. It is transmitted to the back of the liquid crystal panel.

When the groove 40a is formed on the upper surface of the light guide plate 40 adjacent to the light incident surface as described above, the light incident from the LED lamp 42 does not be refracted and passes straight through the light guide plate 40.

That is, when the groove 40a is formed in the upper surface adjacent to the light incident surface of the light guide plate 40, as shown in FIG. 5, the light incident from the first and second light sources (adjacent LED lamps) is the straight light. It has straightness like 1,2.

In this case, the transmitted light 1 and 2 illustrate an example in which no groove is formed in the upper surface of the light incident part of the light guide plate.

When the incident light passes through the general light guide plate without the groove as described above, the light emitted from the first and second light sources passes through the light guide plate and has a small refractive angle with respect to the optical axis, so that the first and second light sources are refracted while passing through the light guide plate. The path where the transmitted light 1 and the transmitted light 2 meet is enlarged, so that a dark area is widely generated.

However, according to the structure proposed by the present invention, the light emitted from the first and second light sources (LED lamps) immediately proceeds without passing through the light guide plate 40 by grooves engraved in the light guide plate 40. The light source emitted from the first and second light sources no longer has a small angle below the incident light with respect to the vertical axis direction, but proceeds directly, where the point where the straight light 1 and the straight light 2 meet in a smaller path than the transmitted light 1 and 2 is generated. Since the area is narrowed, the problem of dark spots can be reduced.

As such, when the light incident between the first and second light sources travels straight due to the grooves 40a formed on the upper surface adjacent to the light incident surface of the light guide plate 40, the area through which the light is transmitted is widened. The dark phenomenon in the light incidence region can be compensated for compared to the prior art.

Second embodiment

6 is a perspective view of the backlight unit according to the second embodiment of the present invention.

In the backlight unit according to the second exemplary embodiment of the present invention, as illustrated in FIG. 6, a light guide plate 40 having grooves 40b formed at regular intervals on a lower surface adjacent to a light incident surface on a rear surface of a liquid crystal panel (not shown) is provided. And a plurality of LED lamps 42 formed on one or both sides of the light guide plate 40, a PCB substrate 41 on which the LED lamps 42 are arranged, and a reflecting plate disposed on a bottom surface of the light guide plate 40. 43).

The reflecting plate 43 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).

Although not shown in the drawings, the lamp housing further includes a lamp housing that completely surrounds the LED lamps 42 and has reflection characteristics therein.

In the above, the groove 40b of the light guide plate 40 is formed in the lower surface of the light guide plate 40 corresponding to the LED lamps 42. The width of the light guide plate 40 decreases gradually as it starts from the light incident surface and moves away from the light incident surface. It is configured to. In addition, the groove 40b may be formed of a round shape or another type of groove.

As described above, the backlight unit according to the second embodiment of the present invention is a backlight unit according to the first embodiment of the present invention, except that the groove 40b is formed on the lower surface of the light guide plate 40 adjacent to the light incident surface. And its configuration is the same.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

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

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

If grooves are formed in the upper or lower surface of the light guide plate adjacent to the light incident surface between the LED lamps, the dark phenomenon between the LED lamps can be improved.

Thereby, the external appearance quality of a backlight unit can be improved.

Claims (6)

The light guide plate, A plurality of LED lamps configured on one or both sides of the light guide plate; And a groove formed in an upper surface of the light guide plate adjacent to a light incident surface corresponding to the LED lamps. The method of claim 1, The groove is a backlight unit, characterized in that configured in the round (round) form or any other form. The method of claim 1, And the groove of the light guide plate is configured to decrease in width as the groove starts at the light incident surface and moves away from the light incident surface. The method of claim 1, And the groove is formed on a lower surface adjacent to a light incident surface corresponding to each other between the LED lamps. The method of claim 1, The backlight unit may include a reflector on a bottom surface of the light guide plate, 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 5, 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.

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