KR20070063181A - Backlight assembly and display device provided with the same - Google Patents

Abstract

A backlight assembly and a display device having the same are provided to improve the uniformity of brightness, by symmetrically setting the thickness of a light guiding plate so as to uniformly output lights, which are incident onto a pair of incidence surface, to an exit surface. A light guiding plate includes a pair of incidence surfaces(741) facing each other, an exit surface(742) connecting lateral sides of the incidence surfaces, and a reflecting surface(743) facing the exit surface. A plurality of light source units(76) apply lights to the incidence surfaces of the light guiding plate. A reflecting member(79) faces the reflecting surface of the light guiding plate. A thickness of the light guiding plate is formed to get smaller from both end portions, where the incidence surfaces are disposed, to the center portion between the incidence surfaces.

Description

BACKLIGHT ASSEMBLY AND DISPLAY DEVICE PROVIDED WITH THE SAME}

1 is an exploded perspective view of a backlight assembly according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.

3 is an exploded perspective view of a display device according to an exemplary embodiment.

4 is a block diagram of a display panel and a configuration for driving the display panel of FIG. 3.

FIG. 5 is an equivalent circuit diagram of one pixel of the display panel of FIG. 4.

* Explanation of symbols for the main parts of the drawings

42: drive integrated circuit chip package 44: printed circuit board

50 display panel 60 first supporting member

70 back light assembly 71 support frame

72: optical sheet 73: second support member

74: light guide plate 75: third support member

76: light source unit 79: reflective member

The present invention relates to a backlight assembly and a display device having the same, and more particularly, to a backlight assembly and a display device having the same, which improve luminance uniformity.

Recently, the demand for display devices such as liquid crystal displays (LCDs), which are smaller and lighter, and whose performance has been improved, is increasing explosively, especially in the rapidly developing semiconductor technology.

Liquid crystal displays have been attracting attention as an alternative means of overcoming the shortcomings of conventional cathode ray tubes (CRTs) because they have advantages such as miniaturization, light weight, and low power consumption, and currently require display devices. In addition to small products such as mobile phones and portable digital assistors (PDAs), they are also used in monitors and TVs, which are medium and large products, and are used in almost all information processing devices requiring display devices.

Such liquid crystal displays convert voltage into specific molecular arrays by applying voltages to specific molecular arrays of liquid crystals, and change the optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell. It is a light-receiving display device which converts into a change and displays information using the modulation of the light by a liquid crystal cell.

A liquid crystal display device, which is a light receiving display device, receives light from a backlight assembly and displays an image on a liquid crystal display panel. The light emitted from the light source unit of the backlight assembly is guided through the light guide plate, and the luminance is improved through the optical sheets disposed on the light guide plate and supplied to the display panel.

However, the light transmitted to the back of the display panel through the conventional light guide plate is not completely uniform.

The present invention has been made to solve the above-described problem, and to provide a backlight assembly with improved uniformity of brightness.

Another object of the present invention is to provide a display device including the backlight assembly.

In order to achieve the above object, a backlight assembly according to the present invention includes a pair of entrance surfaces facing each other, an emission surface connecting one side of the pair of entrance surfaces, and an emission surface facing the emission assembly. A light guide plate having a reflective surface, a plurality of light source units irradiating light onto the incident surfaces of the light guide plate, and a reflective member facing the reflective surface of the light guide plate, wherein the light guide plate is thickest at an end where the incident surface is formed; The thickness becomes thinner toward the center between the pair of incident surfaces.

Here, the exit surface of the light guide plate is flat, the reflective surface of the light guide plate is preferably formed to be inclined.

The light guide plate may have a symmetrical cross section in a direction perpendicular to the incident surface.

The reflective member includes an embossing region and a non-embossing region, wherein the embossing region is formed near the incidence surfaces of the light guide plate, and the non-embossing region is formed between the embossing regions.

In addition, the display device according to the present invention includes a display panel for displaying an image, a pair of incidence surfaces facing each other, an emission surface facing one surface of the pair of incidence surfaces, and facing the rear surface of the display panel; A light guide plate having a reflective surface opposite to the exit surface, a plurality of light source units irradiating light onto the incident surfaces of the light guide plate, and a reflective member facing the reflective surface of the light guide plate, wherein the light guide plate is the incident surface It is thickest at the formed end, and becomes thinner toward the center between the pair of entrance faces.

Here, the exit surface of the light guide plate is flat, the reflective surface of the light guide plate is preferably formed to be inclined.

The light guide plate may have a symmetrical cross section in a direction perpendicular to the incident surface.

The reflective member includes an embossed region and a non-embossed region, wherein the embossed region is formed near the incidence surfaces of the light guide plate, and the non-embossed region is formed between the embossed regions.

Thus, the uniformity of luminance can be improved.

Hereinafter, a backlight assembly according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. This embodiment according to the present invention is only for illustrating the present invention, the present invention is not limited thereto.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

As shown in FIG. 1, the backlight assembly 70 includes a light guide plate 74, a plurality of light source units 76, a light source cover 78, a reflective member 79, an optical sheet 72, and a housing thereof. Support members 71, 73, 75.

The light guide plate 74 has a pair of incidence surfaces facing each other, an emission surface connecting one side of the pair of incidence surfaces, a reflection surface facing the emission surface, and other side surfaces.

The structure of the light guide plate 74 will be described in detail with reference to FIG. 2.

As shown in FIG. 2, the emission surface 742 of the light guide plate 74 is flat and the reflection surface 743 is formed to be inclined. The light guide plate 74 is thickest at each end where the incident surface 741 is formed, and becomes thinner toward the center between the pair of incident surfaces 741. Therefore, the light guide plate 74 is symmetrical in cross section in a direction perpendicular to the incident surface 741. As described above, since the light guide plate 74 is formed in a symmetrical structure, light incident on the pair of incidence surfaces 741 facing each other can be emitted more uniformly through the emission surface 742. In addition, a pattern is formed on the reflective surface 743 of the light guide plate 74 to emit light toward the exit surface 742 as much as possible.

The plurality of light source units 76 irradiate light onto the incident surfaces 741 of the light guide plate 74, respectively. The light source cover 78 surrounding the light source unit 76 reflects all of the light emitted from the light source unit 76 toward the incident surface 741 of the light guide plate 74 to improve light utilization efficiency. Although a lamp is shown as the light source unit 76 in FIG. 1, this is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, a light emitting diode (LED) may be used instead of a lamp, or a light source in the form of a line light source or a surface light source in which the light emitting diode is modularized may be used.

The reflective member 79 faces the reflective surface 743 of the light guide plate 74, and reflects the light emitted from the reflective surface 743 toward the reflective member 79 to the light guide plate 74 to reduce the loss of light. Helping the diffusion of light improves the uniformity of light emitted from the exit surface 742 of the light guide plate 74. As shown in FIG. 2, the reflective member 79 is divided into an embossing region E and a non-embossing region C. As shown in FIG. The embossed region E is formed near the incidence surfaces 741 of the light guide plate 74, respectively, and the non-embossed region C is between the embossed regions E, that is, the incidence surfaces 741 of the light guide plate 74. It is formed in the middle part between.

With this structure, the embossed region E of the reflective member 79 near the incident surface 741 of the light guide plate 74 diffuses the light to diffuse the light further, and the incident surface 741 of the light guide plate 74 is diffused. The non-embossed region C of the reflecting member 79 far away from reflects light. That is, the reflecting member 79 diffuses light by diffusely reflecting the light closer to the light source unit 76 and diffuses the light farther from the light source unit 76 to ensure the luminance by specularly reflecting the light. The uniformity of the overall luminance of the light emitted from the plane 742 may be improved.

The optical sheets 72 face the exit surface 742 of the light guide plate 74 and include optical sheets having various functions. The optical sheets 72 further diffuse and concentrate light emitted from the exit surface 742 of the light guide plate 74 to improve luminance characteristics.

The support members include a first support member 73 for accommodating the light guide plate 74, the light source unit 76, the light source cover 78, the reflective member 79, the optical sheets 72, and the like, and the first support member ( And a second support member 71 and a third support member 75 for fixing them received in combination with the reference numeral 73.

In addition, although not shown in FIG. 1 and FIG. 2, an inverter circuit board is provided on the rear surface of the first support member 73. The inverter circuit board drives the light source unit 76 by transforming external power to a constant voltage level and then applying the wires and sockets connected to the light source unit 76.

As described above, since the backlight assembly 70 uses the light guide plate 74 having a symmetrical structure, the light incident to the pair of incidence surfaces 741 facing each other can be emitted more uniformly through the emission surface 742. have. In addition, since the backlight assembly 70 uses a reflective member 79 divided into an embossed region E and a non-embossed region C, the exit surface 742 of the light guide plate 74 has a uniform brightness as a whole. To help you get out.

3 illustrates a display device 100 according to an exemplary embodiment of the present invention including the backlight assembly 70 of FIG. 1.

In the accompanying drawings, a liquid crystal display panel is shown as an embodiment of the display panel 50 used in the display device 100, but this is merely to illustrate the present invention, and the present invention is limited thereto. It is not. Therefore, the present invention can also be applied to display devices having other light receiving display panels.

As shown in FIG. 3, the display device 100 includes a backlight assembly 70 that supplies light greatly and a display panel 50 that receives light and displays an image. In addition, the display device 100 may further include a fourth support member 60 to fix and support the display panel 50 on the backlight assembly 70, and may further include other necessary portions.

By such a configuration, the display panel 50 may receive light having improved uniformity of luminance through the backlight assembly 70 illustrated in FIG. 1.

The display panel 50 includes a second display panel 53 facing the first display panel 51 with the first display panel 51 and the liquid crystal layer 52 (shown in FIG. 4) interposed therebetween. The first display panel 51 may be a rear substrate, the second display panel 53 may be a front substrate, and the second display panel 53 may have a smaller size than that of the first display panel 51.

In addition, the display device 100 may include a printed circuit board (PCB) 44 and a driver integrated circuit chip package electrically connected to the display panel 50 to transmit a driving signal. 41, 42). The driving integrated circuit chip packages 41 and 42 may use a chip on film (COF) or a tape carrier package (TCP). In addition, the driving integrated circuit chip package includes a gate driving integrated circuit chip package 41 and a data driving integrated circuit chip package 42. The gate driving integrated circuit chip package 41 is attached to one edge of the first display panel 51 and includes an integrated circuit chip 411 constituting the gate driver 400 (shown in FIG. 4). The data driving integrated circuit chip package 42 is attached to the other edge of the first display panel 51 and forms a data driver 500 (shown in FIG. 4) and a gray voltage generator 800 (shown in FIG. 4). An integrated circuit chip 421 is included.

In addition, although not shown in FIG. 3, a control circuit board is provided on the rear surface of the first support member 73 to be electrically connected to the printed circuit board 44. The control circuit board includes a signal controller 600 (shown in FIG. 4) for supplying signals necessary for displaying an image on the display panel 50.

Next, the display panel 50 and the configuration for driving the same will be described in detail with reference to FIGS. 4 and 5.

As shown in FIGS. 4 and 5, the first display panel 51 includes a plurality of signal lines G ₁ -G _n and D ₁ -D _m , and the first display panel 51 and the second display panel ( 53 is connected to the signal lines G ₁ -G _n , D ₁ -D _m and includes a plurality of pixels arranged in an approximately matrix form.

The signal lines G ₁ -G _n , D ₁ -D _m are a plurality of gate lines G ₁ -G _n carrying gate signals (also called “scanning signals”) and data lines D carrying data signals. ₁ -D _m ). The gate lines G ₁ -G _n extend approximately in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Each pixel has a switching element Q connected to a signal line G ₁ -G _n , D ₁ -D _m , and a liquid crystal capacitor C _LC and a storage capacitor C _ST connected thereto. It includes. The holding capacitor C _ST can be omitted as necessary.

An example of the switching element Q may be a thin film transistor, which is formed on the first display panel 51. The thin film transistor is a three-terminal element whose control terminal and input terminal are connected to the gate line (G ₁ -G _n ) and data line (D ₁ -D _m ), respectively, and the output terminals are the liquid crystal capacitor (C _LC ) It is connected to a capacitor C _ST .

The signal controller 600 controls the operations of the gate driver 400 and the data driver 500. The gate driver 400 applies a gate signal formed of a combination of the gate on voltage V _on and the gate off voltage V _off to the gate lines G ₁ -G _n , and the data driver 500 applies the data voltage. Is applied to the data lines D ₁ -D _m . The gray voltage generator 800 generates two sets of gray voltages related to the transmittance of the pixel and provides them to the data driver 500 as data voltages. One of the two sets has a positive value for the common voltage (V _com ) and the other set has a negative value.

As shown in FIG. 5, the liquid crystal capacitor C _LC has two terminals, the pixel electrode 518 of the first display panel 51 and the common electrode 539 of the second display panel 53 as two terminals. The liquid crystal layer 52 between the 539 functions as a dielectric. The pixel electrode 518 is connected to the switching element Q, and the common electrode 539 is formed over the entire surface of the second display panel 53 and receives a common voltage V _com . Unlike in FIG. 5, the common electrode 539 may be provided in the first display panel 51. At this time, at least one of the two electrodes 518 and 539 may be linear or rod-shaped. In addition, a color filter 535 is formed on the second display panel 53 to impart color to the light passing therethrough. Unlike in FIG. 5, the color filter 535 may also be formed on the first display panel 51.

The storage capacitor C _ST , which serves as an auxiliary part of the liquid crystal capacitor C _LC , has a separate signal line (not shown) provided on the first display panel 51 and the pixel electrode 518 overlapping each other with an insulator interposed therebetween. In this separate signal line, a predetermined voltage such as the common voltage V _com is applied. However, the storage capacitor C _ST may be formed such that the pixel electrode 518 overlaps the front gate line G ₁ -G _n directly above the insulator.

Polarizers (not shown) for polarizing light are attached to outer surfaces of at least one of both substrates 51 and 53 of the display panel 50.

By such a configuration, when the thin film transistor as the switching element is turned on, an electric field is formed between the pixel electrode 518 and the common electrode 539. Such an electric field causes the liquid crystal array angle of the liquid crystal layer 53 formed between the first display panel 51 and the second display panel 53 to be changed, thereby obtaining a desired image due to the changed light transmittance.

Although the present invention has been described above, it will be readily understood by those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the claims set out below.

As described above, according to the present invention, the uniformity of luminance can be improved.

That is, the light guide plate is the thickest in the pair of entrance faces facing each other, the thickness becomes thinner toward the middle between the entrance faces and the exit face is formed flat and has a symmetrical structure as a whole. Each incident light can be emitted more uniformly through the emission surface.

In addition, since the reflective member is divided into an embossed region and a non-embossed region to reflect light, the emission surface of the light guide plate may emit light with a uniform luminance as a whole.

Claims (8)

A light guide plate having a pair of entrance surfaces facing each other, an emission surface connecting one side of the pair of entrance surfaces, and a reflection surface facing the emission surface, A plurality of light source units irradiating light onto incident surfaces of the light guide plate, and Reflecting member facing the reflecting surface of the light guide plate Including; The light guide plate is thickest at the end where the incident surface is formed, and becomes thinner gradually toward the center between the pair of incident surfaces. In claim 1, And a light emitting surface of the light guide plate is flat and a reflective surface of the light guide plate is inclined. In claim 1, The light guide plate has a cross-section in a direction perpendicular to the incident surface is symmetrical to the backlight assembly. In claim 1, The reflective member includes an embossing region and a non-embossing region, And the embossed region is formed near the incident surfaces of the light guide plate, and the non-embossed region is formed between the embossed regions. Display panel for displaying images, A light guide plate having a pair of incidence surfaces facing each other, an emission surface connecting the one side of the pair of incidence surfaces and facing the rear surface of the display panel, and a reflective surface opposite to the emission surface, A plurality of light source units irradiating light onto incident surfaces of the light guide plate, and Reflecting member facing the reflecting surface of the light guide plate Including; The light guide plate is thickest at an end portion at which the incident surface is formed, and becomes thinner toward the center between the pair of incident surfaces. In claim 5, And a light emitting surface of the light guide plate is flat and a reflective surface of the light guide plate is inclined. In claim 5, The light guide plate is a display device in which the cross section of the direction perpendicular to the incident surface is symmetrical. In claim 5, The reflective member includes an embossed region and a non-embossed region, The embossed region is formed near the incident surfaces of the light guide plate, and the non-embossed region is formed between the embossed regions.

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