KR20060104301A - Backlight assembly and display apparatus provided with the same - Google Patents

Abstract

The present invention relates to a backlight assembly and a display device having the same. The backlight assembly according to the present invention comprises a lamp unit including a lamp unit for generating light and an electrode unit formed at both ends of the lamp unit, and an incident surface facing the lamp unit and light emitted from the incident surface are guided and emitted. And a light guide plate having a surface, and an incident light diffusing portion is formed on a part of the incident surface near the electrode portion.

Display device, backlight assembly, light guide plate, incident light diffuser

Description

Backlight assembly and display device having same {BACKLIGHT ASSEMBLY AND DISPLAY APPARATUS PROVIDED WITH THE SAME}

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

FIG. 2 is a diagram illustrating the structure of the light guide plate and the lamp unit of FIG. 1.

3 is a view showing the structure of a light guide plate and a lamp unit according to a second embodiment of the present invention.

4 is an exploded perspective view of a display device according to an exemplary embodiment of the present invention.

5A and 5B are diagrams each showing an experimental example and a comparative example according to the present invention.

* Explanation of symbols for the main parts of the drawings

20: display panel assembly 21: display panel

30 backlight unit 31 light guide plate

32 lamp unit 34 lamp holder

36: optical sheet 40: lower mold frame

50: top chassis 60: upper mold frame

The present invention relates to a display device, and more particularly, to a display device including a light guide plate which is improved to minimize locally generated dark portions.

The display device refers to a device for receiving an image signal information from the outside to form an image. BACKGROUND ART With the recent rapid development of semiconductor technology, display devices have become smaller and lighter, and the demand for such display devices has exploded. In general, flat panel display panels used in small and lightweight display devices include field emission display (FED), vacuum fluorescent display (VFD), and liquid crystal display (LCD). Organic light emitting display (OLED) and plasma display panel (PDP). Although the detailed structure of the display panel varies depending on the type, the display panel generally includes a pair of substrates installed to face each other, and the inside of the display panel is maintained at a high vacuum.

Among them, a display device using a liquid crystal display panel, which has recently been in the spotlight, has advantages such as miniaturization, light weight, and low power consumption, and thus, is increasingly being used as an alternative means to overcome the disadvantages of the conventional cathode ray tube (CRT). Nowadays, it is installed and used in almost all information processing apparatuses that require a display device.

In general, a liquid crystal display device applies a voltage to a specific molecular array of a liquid crystal to convert it into another molecular array, and visually changes optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell emitted by the molecular array. It is a light-receiving display device that displays information using modulation of light by a liquid crystal cell, which is converted into a change.

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 lamp unit of the backlight assembly is guided through the light guide plate, and the luminance is improved while passing through the optical sheets placed on the light guide plate and supplied to the liquid crystal display panel.

In the backlight assembly, a lamp unit, which is a light source, is disposed on a rear surface of the liquid crystal display panel to irradiate light to the liquid crystal display panel, and a light guide plate is provided on the rear surface of the liquid crystal display panel, and the lamp unit is disposed on at least one side of the light guide plate It is divided into an edge method for irradiating light to the liquid crystal display panel through the light guide plate.

The edge method is mainly used for small and medium sized display devices. In such an edge method, a lamp unit is disposed on one side of the light guide plate and a light guide plate is formed in a wedge shape, called a wedge type backlight assembly.

In the wedge-shaped backlight assembly, a lamp unit having a lamp unit for emitting light and electrode units formed at both ends thereof is disposed at one side of the light guide plate to supply light. However, in recent years, as a slimmer display device is required, an electrode portion of a lamp unit and a lamp holder supporting the lamp unit are disposed to face inside the incident surface in a corner region of the light guide plate. That is, in the corner region of the light guide plate opposite to the electrode portion, it is difficult to properly transmit the light emitted from the lamp portion. As a result, a small amount of light is incident from the lamp unit or no light is incident on the corner region of the light guide plate adjacent to the electrode of the lamp unit. Therefore, the image displayed on the display panel exhibits a distinct difference in contrast ratio in the corner region where the dark portion is generated and in other regions.

Accordingly, an object of the present invention is to provide a display device having an improved light guide plate so as to minimize dark portions generated locally in a corner region adjacent to an electrode portion of a lamp unit.

The backlight assembly according to the present invention for achieving the above object comprises a lamp unit for generating light and an electrode unit formed on both ends of the lamp unit and the incident surface facing the lamp unit, and incident to the incident surface And a light guide plate having an emission surface through which the emitted light is guided and emitted, and an incident light diffusion part is formed on a part of the entrance surface in the vicinity of the electrode part.

Preferably, the incident light diffusing portion has a plurality of concave portions and protrusions continuously formed so that grooves are formed in the thickness direction of the light guide plate.

Here, it is preferable that the plurality of recesses and protrusions form a sawtooth shape.

The right angle of the protrusion is preferably 70 ° to 110 °.

The pitch between the plurality of protrusions is preferably 300 μm or less.

The plurality of recesses and protrusions may be formed in non-uniform sizes, respectively.

The plurality of recesses and protrusions may be formed substantially in a semicircular shape.

The total length of the incident light diffuser is preferably 10 mm to 50 mm.

The light guide plate may further include a fixing member configured to accommodate the light guide plate, and a portion of the fixing member facing the side surface of the light guide plate may be made of a material capable of diffusing and reflecting light.

A display device according to the present invention includes a display panel for displaying an image, a lamp unit for generating light, and a lamp unit including an electrode part formed at both ends of the lamp unit, and an incident surface facing the lamp unit and the display panel. And a light guide plate having an opposite exit face and guiding light generated by the lamp unit to the display panel, wherein an incident light diffuser is formed on a part of the incident face in the vicinity of the electrode part.

Preferably, the incident light diffusing portion is formed with a plurality of recesses and protrusions continuously so that grooves are formed in the thickness direction of the light guide plate.

Here, the plurality of recesses and protrusions may form a sawtooth shape.

The right angle of the protrusion is preferably 70 ° to 110 °.

The pitch between the plurality of protrusions is preferably 300 μm or less.

The plurality of recesses and protrusions may be formed in non-uniform sizes, respectively.

The plurality of recesses and protrusions may be formed substantially in a semicircular shape.

The total length of the incident light diffuser is preferably 10 mm to 50 mm.

The light guide plate may further include a fixing member configured to accommodate the light guide plate, and at least a portion of the fixing member facing the side surface of the light guide plate may include a material capable of diffusing and reflecting light.

Accordingly, it is possible to minimize the dark portion generated locally in the corner region of the light guide plate adjacent to the electrode portion of the lamp unit.

Hereinafter, a display device according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, a wedge type backlight assembly is schematically illustrated as an embodiment. These embodiments according to the present invention are merely for illustrating the present invention, the present invention is not limited thereto.

In addition, prior to description, in the various embodiments, components having the same configuration will be described in the first embodiment by using the same reference numerals, and in other embodiments, only the configuration different from the first embodiment will be described. Let's do it.

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.

A first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1, the backlight assembly 30 according to the first embodiment of the present invention includes a lamp unit 32 for supplying light, a lamp holder 34 for supporting the lamp unit 32, and a lamp. A light guide plate 31 having an incident surface 312 facing the unit 32 and an exit surface 311 that emits light incident from the incident surface 312 and is orthogonal to the incident surface 312, and a lamp unit A lamp cover 35 which surrounds the periphery of the lamp 32 to protect the lamp unit 32 and reflects the light emitted from the lamp unit 32 toward the light guide plate 31, and an exit surface of the light guide plate 31. A reflection sheet 35 disposed on a surface opposite to 311 to reflect light, and an optical arrangement disposed on the exit surface 311 of the light guide plate 31 to improve brightness of the light emitted from the exit surface 311; Sheets 36 are included. In addition, the apparatus further includes an upper mold frame 60 and a lower mold frame 40 that accommodate and support them. Here, when the backlight assembly 30 is used in the display device, the emission surface 311 of the light guide plate 31 is disposed to face the display panel.

The lamp unit 32 includes a lamp unit 321 for emitting light and an electrode unit 322 formed at both ends of the lamp unit 321. The electrode unit 322 is connected to an inverter (not shown) to receive the necessary power. In some cases, a plurality of lamp units 32 may be provided on the incident surface 312 of the same light guide plate 31. The lamp holder 34 supports and fixes the electrode portion 322 of the lamp unit 32. In addition, as an increasingly slim product is required, both the electrode portion 322 of the lamp unit 32 and the lamp holder 34 supporting the same are disposed in the incident surface 312 of the light guide plate 31.

The light guide plate 31 diffuses light incident from the lamp unit 32 to the incident surface 312 and exits through the emission surface 311 substantially uniformly. That is, when the backlight assembly 30 is used in the liquid crystal display device, the light guide plate 31 transmits light uniformly diffused to the display panel. The light guide plate 31 is made of polymethylmethacrylate (PMMA) having a high strength and is not easily deformed or broken and has a good transmittance. On the lower surface of the light guide plate 31, a pattern is formed to become denser as it moves away from the lamp unit 32 to emit light toward the exit surface 311 as much as possible.

The light guide plate 31 according to the first embodiment of the present invention includes an incident light diffusing portion 315 formed on at least a portion of the incident surface 312 adjacent to the electrode portion 322 of the lamp unit 32. The incident light diffusing portion 315 is formed with a plurality of recesses and protrusions so that grooves are formed in the thickness direction (Z-axis direction) of the light guide plate 31. That is, the recess and the protrusion have a length along the thickness direction (Z-axis direction) of the light guide plate 31. The incident light diffusion part 315 is formed in a sawtooth (serration) cross section. In this case, a plurality of recesses and protrusions may be formed in non-uniform sizes, respectively, to further improve light diffusion. And the right angle of a protrusion part, ie, the angle which the vertex of a protrusion part makes, has an angle of 70 degrees-110 degrees. If the right angle is smaller than 70 °, light is difficult to diffuse, and if the right angle is larger than 110 °, the light may be excessively scattered and luminance may decrease. In addition, the pitch (P, pitch) between each projection is 300㎛ or less, the smaller the pitch (P) is advantageous to diffuse the light. The total length of the incident light diffusion portion 315 is approximately 10 mm to 50 mm. If the total length of the incident light diffusion unit 315 is less than 10 mm, the light diffusion effect is insignificant, and if it exceeds 50 mm, the light may be excessively diffused and luminance may be lowered. In addition, the incident light diffuser 315 may be formed at a corner from the corner of the light guide plate 31. This distance can be appropriately adjusted according to the length of the electrode portion 321 which does not generate light or the length of the lamp holder 34.

The optical sheet 36 includes a diffusion sheet 361 and a diffusion sheet 361 which diffuse light so that the light emitted from the exit surface 311 of the light guide plate 31 is not partially concentrated, thereby further improving the uniformity of the light. ) And a prism sheet 362 to improve the luminance by allowing the light passing through the vertical direction to proceed vertically. In addition, the diffusion sheet 361 and the prism sheet 362, which is sensitive to dust and scratches, and may further include a protective sheet 363 to prevent the external impact or foreign matter inflow. The optical sheets 36 may be integrally formed, and the upper surface of the light guide plate 31 may be formed to perform at least some functions of the optical sheets 36. When the backlight assembly 30 is used in the display device, partial concentration of light emitted from the emission surface 311 of the light guide plate 31 may cause spots on the display panel.

On the other hand, since more light is transmitted to the corner region of the light guide plate 31 by the incident light diffuser 315 formed on the light guide plate 31, the luminance which is raised in the optical sheets 36 positioned thereon also increases. .

The reflective sheet 35 reflects the light emitted from the light guide plate 31 to the opposite side of the light emitting plate 311 back to the light guide plate 31, thereby reducing the loss of light and helping to diffuse the light from the light emitting plate 311. It contributes to improving the uniformity of the emitted light.

At least a portion of the upper mold frame 60 and the lower mold frame 40 facing the side surface of the light guide plate 31 is made of a material capable of diffusing and reflecting light. As such a material, polycarbonate (PC) or the like may be used. Thus, the amount of light directed to the dark portion generated in the corner region of the light guide plate 31 adjacent to the electrode portion 322 of the lamp unit 32 may be increased to help minimize the dark portion.

FIG. 2 more clearly shows the effect of removing the dark portion due to the incident light diffuser 315 formed in the light guide plate 31. Light incident on the light guide plate 31 through the incident light diffuser 315 is further diffused in the lateral direction of the light guide plate 31, and thus, the corner region of the light guide plate 31 facing the electrode part 322 of the lamp unit 32. Increasing the amount and range of the incident light can be minimized locally generated dark areas. That is, since light is not incident on the portion of the light guide plate 31 facing the lamp holder 34, the dark portion is easily formed. In the present invention, since light is diffused through the incident light diffuser 315, the dark portion is suppressed.

A second embodiment of the present invention will be described with reference to FIG.

In the backlight assembly 30 according to the second exemplary embodiment of the present invention illustrated in FIG. 3, the incident light diffuser 315 formed on the incident surface 312 of the light guide plate 31 is formed in a substantially semi-circular shape. As described above, even when the incident light diffusing portion 315 is formed in a semicircular shape, it is locally generated in the corner region of the light guide plate 31 adjacent to the electrode portion 322 of the lamp unit 32, similarly to the first embodiment described above. The dark part can be minimized.

In addition, the shape of the incident light diffuser 315 is not limited to the first and second embodiments, and the light incident from the lamp unit 32 can be further diffused in the lateral direction of the light guide plate 31. Any shape may be used.

4 illustrates a display device 100 according to an exemplary embodiment of the present invention. The display device 100 is illustrated using the backlight assembly 30 illustrated in 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, but this is merely to illustrate the present invention, but the present invention is not limited thereto. Therefore, the present invention can also be applied to display devices having other light receiving display panels.

As shown in FIG. 4, the display device 100 includes a backlight assembly 30 that supplies light and a display panel assembly 20 that displays an image using light according to the present invention. A top chassis 50 is used to securely couple the display panel assembly 20 to the backlight assembly 30. According to the use of the display device 100 and the type of the backlight assembly 30, only one mold frame 40 and 60 as a fixing member may be used, and a bottom chassis instead of the mold frames 40 and 60 may be used. Not shown) may be used, and at least one of the mold frames 40 and 60 and the bottom chassis (not shown) may be used together.

The display panel assembly 20 includes a display panel 21, driver integrated circuit packages 23 and 24, and a printed circuit board (PCB) 22. Include. The driving IC packages 23 and 24 may be formed of a chip on film (COF) or a tape carrier package (TCP). Here, the display panel 21 uses a liquid crystal display panel. However, the display panel 21 is not necessarily limited to a liquid crystal display panel, and other light receiving display panels may be used.

The display panel 21 includes a thin film transistor substrate 211 on which a plurality of thin film transistors (TFTs) are formed, a color filter substrate 212 disposed opposite to the thin film transistor substrate 211, and both substrates 211 and 212. It includes a liquid crystal (not shown) injected between). Although not shown, a polarizer is attached to the front surface of the color filter substrate 212 and the rear surface of the thin film transistor substrate 211 to linearly polarize the visible light supplied from the backlight assembly 30.

The thin film transistor substrate 211 includes a plurality of gate lines and a plurality of data lines formed in a matrix form on a transparent insulating substrate, a thin film transistor (TFT) formed at an intersection of the gate line and the data line, and a thin film transistor. And a pixel electrode made of transparent indium tin oxide (ITO) as an electrically conductive material. The thin film transistor has a source terminal connected to a data line, a gate terminal connected to a gate line, and a drain terminal connected to a pixel electrode.

Therefore, the electrical signal information supplied from the PCB 22 is transferred to the gate line and the data line of the display panel 21 and input to the source terminal and the gate terminal of the thin film transistor, and the thin film transistor forms a pixel according to the signal information. The electrical signal required to turn on or off is switched to switch the pixel electrode connected to the drain terminal.

On the other hand, the color filter substrate 212 is disposed on the thin film transistor substrate 211. The color filter substrate 212 is a substrate in which pixels of three primary colors (red, green and blue or cyan, magenta and yellow), which are color pixels in which a predetermined color is expressed while light passes, are formed. An electrode is formed. When the thin film transistor, which is a switching element, is turned on, an electric field is formed between the pixel electrode and the common electrode. The array angle of the liquid crystal injected between the thin film transistor substrate 211 and the color filter substrate 212 is changed by the electric field, and thus, the desired pixel is obtained by the changed light transmittance.

The gate line and the data line of the thin film transistor substrate 211 receive a driving signal and a timing signal to control the arrangement angle of the liquid crystal and the timing of arranging the liquid crystal. The driving IC packages 23 and 24 are attached to determine the application timing of the data driving signal and the gate driving signal applied to the gate line and the data line.

The PCB 22 for receiving a video signal from the outside and applying driving signals to the data line and the gate line of the display panel 21 is connected to the driving IC packages 23 and 24 attached to the display panel 21. . The PCB 22 generates a data driving signal for driving the display device 100, a gate driving signal, and a plurality of driving signals for applying these signals at an appropriate time, thereby driving the gate driving signal and the data driving signal to drive IC package. It is applied to the gate line and the data line of the display panel 21 through the 23 and 24, respectively.

The backlight assembly 30 is disposed below the display panel assembly 20 to uniformly provide light to the display panel 21. The upper mold frame 60 supports the display panel 21.

Although not shown, an inverter installed outside the display device 100 converts an external power supply to a constant voltage level to provide the lamp unit 32, and a control board is connected to the PCB 22 described above. The analog data signal is converted into a digital data signal and then provided to the display panel 21.

The top chassis 50 is provided on the display panel assembly 20 to prevent the display panel assembly 20 from being separated from the backlight assembly 30 while bending the data side driver IC package 24.

Hereinafter, the present invention will be described in more detail through experimental examples.

These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.

Experimental Example

Simulation experiments were conducted on a wedge-shaped 15-inch liquid crystal display. After the light guide plate having the same shape as that of the first embodiment of the present invention was installed in the display device, an optical waveguide path was observed by applying a voltage to the lamp. The optical waveguide is shown in Fig. 5A. In FIG. 5A, reference numeral 321 denotes a lamp unit, 34 denotes a lamp holder, and 31 denotes a light guide plate.

Comparative example

Simulation experiments were conducted on a wedge-shaped 15-inch liquid crystal display. After installing the light guide plate on which the incident light diffusing portion is not formed in the liquid crystal display as in the prior art, a voltage was applied to the lamp unit to observe the optical waveguide path. The optical waveguide is shown in Fig. 5B.

As shown in FIG. 5A, it was found that the dark portion was significantly reduced due to the light incidence diffusion portion formed in the light guide plate 31. This is indicated by an arrow. In contrast, in the comparative example of the related art of FIG. 5B, it can be seen that the dark portion is prominent in the corner region of the light guide plate 31.

As described above, according to the present invention, it is possible to provide a display device having an improved light guide plate so as to minimize a dark portion locally generated at a corner region adjacent to an electrode portion of a lamp unit.

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.

Claims (18)

A lamp unit including a lamp unit for generating light and electrode parts formed at both ends of the lamp unit; And A light guide plate having an entrance surface facing the lamp unit and an exit surface on which light incident on the entrance surface is guided and exited; Including; A backlight assembly having an incident light diffusion portion formed in a part of the incident surface near the electrode portion. The method of claim 1, And a plurality of recesses and protrusions continuously formed such that the incident light diffuser is formed with a groove in the thickness direction of the light guide plate. The method of claim 2, And a plurality of recesses and protrusions having a sawtooth shape. The method of claim 2, The right angle of the protrusion is 70 ° to 110 ° backlight assembly. The method of claim 2, The pitch between the plurality of protrusions is less than 300㎛ backlight assembly. The method of claim 2, And the plurality of recesses and protrusions are formed in non-uniform size, respectively. The method of claim 2, And the plurality of recesses and protrusions are substantially semicircular. The method of claim 1, The total length of the incident light diffusion portion 10mm to 50mm backlight assembly. The method of claim 1, Further comprising a fixing member for receiving the light guide plate, A portion of the fixing member facing the side of the light guide plate includes a material capable of diffusing and reflecting light. A display panel displaying an image; A lamp unit including a lamp unit for generating light and electrode parts formed at both ends of the lamp unit; And A light guide plate having an incident surface facing the lamp unit and an exit surface facing the display panel to guide the light generated by the lamp unit to the display panel. Including; And a light incident diffusion part formed on a part of the incident surface near the electrode part. The method of claim 10, And a plurality of concave portions and protrusions continuously formed such that the incident light diffusing portion has a groove formed in the thickness direction of the light guide plate. The method of claim 11, And a plurality of recesses and protrusions having a sawtooth shape. The method of claim 11, And a right angle of the protrusion is 70 ° to 110 °. The method of claim 11, The pitch of the plurality of protrusions is 300㎛ or less. The method of claim 11, And a plurality of concave portions and protrusions each having a non-uniform size. The method of claim 11, And a plurality of recesses and protrusions are substantially semi-circular. The method of claim 10, The entire length of the incident light diffusion portion is 10mm to 50mm. The method of claim 10, Further comprising a fixing member for receiving the light guide plate, And a portion of the fixing member facing the side surface of the light guide plate including a material capable of diffusing and reflecting light.

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