KR101171179B1 - Display apparatus - Google Patents

Abstract

The present invention relates to a display device, comprising: a display panel for displaying an image, a light source unit for supplying light to the display panel, a printed circuit board on which the light source unit is mounted, and a reflective film is formed around the light source unit, and the light source unit Forming a light guide portion for guiding the light emitted from the light source unit to the display panel having an incident surface opposite to the display panel and an emission surface facing the display panel, and a storage space for accommodating the display panel along an edge of the light guide portion; It includes a light guide unit having a side wall portion.

Display Devices, Light Emitting Diodes, Printed Circuit Boards, Reflective Films, Fabrication, Light Leaks

Description

Display device {DISPLAY APPARATUS}

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

FIG. 2 is a perspective view illustrating a coupling state of the light guide unit and the printed circuit board of FIG. 1.

3 is a view schematically illustrating a path of light passing through the light guiding unit of FIG. 1.

4 is a perspective view illustrating a light blocking film and a reflective film attached to the light guide unit of FIG. 1.

DESCRIPTION OF THE REFERENCE NUMERALS

10: display device 210: main display panel

220: sub-display panel 230: first flexible circuit board

240: second flexible circuit board 250: printed circuit board

253: reflective film 300: first backlight assembly

310: first light source unit 330: first optical sheet

400: second backlight assembly 410: second light source unit

420: light guide unit 430: second optical sheet

440: reflector 550: mold frame

The present invention relates to a display device, and more particularly, to a display device that can improve brightness while simplifying an assembly process of a backlight assembly.

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, the type of flat panel display panel used in a small and lightweight display device includes a field emission display (FED), a vacuum fluorescence display (VFD), and a liquid crystal display (LCD). ), An organic light emitting display (OLED), and a 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, liquid crystal displays (LCDs) using liquid crystal display panels, which have recently been in the spotlight, have advantages such as miniaturization, light weight, and low power consumption. It is used.

In general, a liquid crystal display (LCD) applies a voltage to a specific molecular array of a liquid crystal to convert it into another molecular array, and optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell that emit light by the molecular array. A light-receiving display device that converts a change of the light into a visual change and displays information by using modulation of 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 while passing through the optical sheets placed on the light guide plate and supplied to the liquid crystal display panel.

However, the conventional backlight assembly is composed of many configurations such as a light source unit, a light guide plate, optical sheets, and a mold frame for storing and supporting them.

Thus, the assembly process of the backlight assembly is complicated, there is a problem that the assembly work time is increased and the probability that a defect occurs in the assembly step is increased. In addition, when the positions of the components constituting the backlight assembly are shifted due to an external impact or the like, a problem that the light emitted from the light source unit may not be effectively utilized may occur. In particular, in the case of a display device used for a clamshell cell phone having two display panels attached to front and back surfaces of a folder, for example, the structure of the backlight assembly may be more complicated, and thus the above-mentioned problems may be more highlighted.

In addition, there is a problem in that light leakage occurs in the path of light until the light emitted from the light source unit reaches the light guide plate and is guided by the light guide plate, thereby causing a loss of light.

Accordingly, an object of the present invention is to provide a display device that maximizes light efficiency while simplifying an assembly process.

A flat panel display device according to the present invention includes a display panel for displaying an image, a light source unit for supplying light to the display panel, a printed circuit board on which the light source unit is mounted, and a reflective film is formed around the light source unit, and the light source unit Forming a light guide portion for guiding the light emitted from the light source unit to the display panel having an incident surface opposite to the display panel and an emission surface facing the display panel, and a storage space for accommodating the display panel along an edge of the light guide portion; It includes a light guide unit having a side wall portion.

The reflective film may be formed by silk coating.

The reflective film may be made of a material including silver paste.

The light guide unit may be coupled to the printed circuit board, and a reflector may be mounted on at least a portion of the printed circuit board coupled to the light guide unit.

The light source unit is preferably made including a light emitting diode.

Accordingly, a display device may be provided that maximizes light efficiency by preventing light leakage and improving light brightness while simplifying an assembly process.

Hereinafter, a display device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, a display device in which a twin backlight assembly is used as an embodiment, that is, a dual clamshell cell phone is schematically illustrated. These embodiments according to the present invention are merely 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.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, the display device 10 according to an exemplary embodiment of the present invention has a large display panel assembly 200 and a backlight assembly 300 for supplying light to the display panels 210 and 220, respectively. 400). In addition, the apparatus further includes a top chassis 510, a mold frame 550, and a bottom chassis 520 to fix and support them.

The display panel assembly 200 includes a main display panel 210, a sub display panel 220, a first flexible circuit board 230, a second flexible circuit board 240, and a printed circuit board (PCB). ) 250, and an integrated circuit chip 260. The integrated circuit chip 260 may be formed of a chip on film (COF) or a tape carrier package (TCP).

Although two display panels 210 and 220 are shown in FIG. 1, this is merely to illustrate the present invention, but the present invention is not limited thereto. Therefore, it is only necessary to include two or more, that is, at least two display panels. In addition, although two liquid crystal display panels are illustrated in FIG. 1 as the display panels 210 and 220, these are merely to illustrate the display panel used in the present invention, and the present invention is not limited thereto. Therefore, one or more liquid crystal display panels may be included, or other light receiving display panels may be used.

The main display panel 210 is larger than the sub display panel 220 facing the main display panel 210. In particular, the display device 10 may be used for a cellular phone. The main display panel 210 is located on the inner surface of the cellular phone folder and the sub display panel 220 is located on the outer surface of the cellular phone folder. Therefore, when the folder is closed, a relatively small amount of information such as time can be contacted through the sub display panel 220 having a small screen size, and the main display panel 210 having a large screen size is opened by opening a folder when talking to the other party. ), You can access a relatively large amount of information.

Hereinafter, the internal structure of the main display panel 210 which is a liquid crystal display panel will be described in detail. Since the structure of the sub display panel 220 is the same as that of the main display panel 210, a detailed description thereof will be omitted.

The main display panel 210 includes a first thin film transistor substrate 211 having a plurality of thin film transistors (TFTs), a first color filter substrate 212 disposed to face the first thin film transistor substrate 211, and Liquid crystals (not shown) injected between these substrates 211 and 212 are included. Although not shown, a polarizer is attached to the front surface of the first color filter substrate 212 and the rear surface of the first thin film transistor substrate 211 to linearly polarize the visible light supplied from the backlight assembly 300.

The first thin film transistor substrate 211 is electrically connected to 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 formed at an intersection of the gate line and the data line, and a thin film transistor. The conductive material includes a pixel electrode made of transparent indium tin oxide (ITO). 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.

Accordingly, electrical signal information is transmitted from the printed circuit board 250 to the gate line and the data line of the main display panel 210 through the first flexible circuit board 230 and input to the source terminal and the gate terminal of the thin film transistor. According to the signal information, the thin film transistor turns on or off an electrical signal necessary for pixel formation to switch the pixel electrode connected to the drain terminal.

On the other hand, the first color filter substrate 212 is disposed on the first thin film transistor substrate 211. The first 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. A common 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 arrangement angle of the liquid crystal injected between the first thin film transistor substrate 211 and the first color filter substrate 212 is changed by this electric field, thereby obtaining a desired pixel by the changed light transmittance. .

The gate line and the data line of the first 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 integrated circuit chip 260 is mounted on the first thin film transistor substrate 211 and surrounded by a protective film. The integrated circuit chip 260 receives a driving signal from the printed circuit board 250 through the first flexible circuit board 230, and includes a data driving signal, a gate driving signal, which is a signal for driving the main display panel 210. A plurality of timing signals are generated to apply these signals at appropriate times, and the gate driving signal and the data driving signal are applied to the gate line and the data line of the main display panel 210, respectively.

The sub display panel 220 includes a second thin film transistor substrate 221 and a second color filter substrate 222, and is the same as the main display panel 210 through the second flexible circuit board 240. The driving signal transmitted from the printed circuit board 250 is received through another integrated circuit chip (not shown).

A plurality of resistors 255 are mounted on the printed circuit board 250 that transmits signals to the first flexible circuit board 230 and the second flexible circuit board 240, and the cell phone connector 256 is provided at an end thereof. Is mounted. The first flexible circuit board 230 receives a signal according to the opening and closing degree of the folder window for the mobile phone through the mobile phone connector 256. The first flexible circuit board 230 connects the main display panel 210 and the printed circuit board 250. In FIG. 1, the first flexible circuit board 230 is cut off for convenience of illustration, but is actually connected.

The backlight assembly may be in contact with each other while providing light emitted from the light source units 310 and 410 to both display panels 210 and 220 between the main display panel 210 and the sub display panel 220. 300 and the second backlight assembly 400. In one embodiment according to the present invention, the first backlight assembly 300 is housed in the mold frame 550, and the second backlight assembly 400 is coupled to the printed circuit board 250. However, this is merely illustrative of the present invention and the present invention is not limited thereto. Therefore, the second backlight assembly 400 may also be directly coupled to and supported by the mold frame 550, and may be modified in various structures.

The first backlight assembly 300 may include a first light source unit 310 that supplies light to the main display panel 210, and a light guide plate that guides light emitted from the first light source unit 310 to the main display panel 210. 320, a reflective sheet 340 for reflecting light, a first optical sheet 330 for improving the luminance of the light emitted from the light guide plate 320 to be supplied to the main display panel 210, and storing and supporting them. A mold frame 550. Although FIG. 1 shows a light emitting diode (LED) 311 mounted on the flexible substrate 312 as the first light source unit 310, this is merely to illustrate the present invention, and the present invention It is not limited to this. Therefore, not only another light source such as a lamp may be used as the first light source unit 310 but also a line light source and a surface light source in which the light emitting diode 311 is modularized. Also, although the number of light emitting diodes 311 is shown as three, this is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, the number of light emitting diodes 311 can be varied as needed. The flexible substrate 312 is connected to the printed circuit board 250 to receive a light source control signal therefrom to drive the light source unit 310.

The first optical sheet 330 further diffuses the light from the light guide plate 320 toward the main display panel 210 so that spots do not occur on the main display panel 210, thereby further improving the uniformity of the light. And a prism sheet for improving the luminance by allowing the light passing through the diffusion sheet to proceed vertically. The apparatus may further include a protective sheet that protects the diffusion sheet and the prism sheet sensitive to dust or scratches and prevents external impact or foreign material from entering.

The reflective sheet 340 reflects the light emitted in the opposite direction of the main display panel 210 through the light guide plate 320 back to the light guide plate 320, thereby reducing the loss of light and helping to spread the light. This contributes to improving the uniformity of the light directed toward).

The mold frame 550 accommodates and supports the first light source unit 310, the light guide plate 320, the reflective sheet 340, and the first optical sheets 330, and together with the main display panel 210. It is stored and supported. The top chassis 510 and the bottom chassis 520 are disposed on the upper and lower portions of the mold frame 550 containing these components, respectively, which are coupled to the sides of the mold frame 550.

The second backlight assembly 400 is coupled to the second light source unit 410 and the printed circuit board 250 to supply light to the sub display panel 220, according to the present invention, from the second light source unit 410. The light guide unit 420 guides the emitted light to the sub display panel 220 and accommodates and supports the second optical sheet 430 and the sub display panel 220. In addition, the light guide unit 420 may further include a reflector 440 disposed between the printed circuit board 250. The printed circuit board 250 directly coupled with the light guide unit 420 is disposed under the bottom chassis 520.

A predetermined fastening hole 251 is formed in the printed circuit board 250 that is coupled to the light guide unit 420. The reflective plate 440 is mounted on at least a portion of the printed circuit board 250 that is coupled to the light guide unit 420. The reflective plate 440 may be mounted on the printed circuit board 250 using a double-sided tape or an adhesive.

As shown in FIG. 2, the second light source unit 410 is directly mounted on the surface of the printed circuit board 250 in the direction in which the light guide unit 420 is coupled. In addition, a reflective film 253 is formed around the printed circuit board 250 where the second light source unit 410 is mounted. The second light source unit 410 may include a light emitting diode and may be directly mounted on the printed circuit board 250 using soldering. The reflective film 253 is silk coated or made of a material including silver paste, and has a white or silver color to reflect light. The reflective film 253 may be generated when the light emitted from the second light source unit 410 is emitted to the sub display panel 220 (220 is shown in FIG. 1) through the light guide unit 420. It will suppress the loss of light. In particular, the light emitted from the second light source unit 410 suppresses the loss of light that may occur before reaching the place where the reflector 440 is formed.

As such, in the display device 10 according to the exemplary embodiment, the second light source unit 410 may be directly mounted on the printed circuit board 250 to simplify the assembly process. In addition, the reflective film 253 is formed on the printed circuit board 250 so that the light emitted from the second light source unit 410 is guided by the light guide unit 420 before reaching the place where the reflective plate 440 is formed. By suppressing the loss of light that can occur in the previous light path, brightness can be improved to maximize light efficiency.

The light guide unit 420 has an incident surface facing the second light source unit 410 and an exit surface facing the sub display panel 220, and emits light emitted from the second light source unit 410 to the sub display panel 220. A second optical sheet 430 (refer to reference numeral 430 shown in FIG. 1) integrally extending along the edge of the light guide portion 421 and along the edge of the light guide portion 421 toward the sub display panel 220. And a sidewall portion 422 forming a storage space for accommodating the sub display panel 220, and a fixing portion 423 for fixing the light guide portion 421. Here, the fixing part 423 has a convex shape to be inserted into the fastening hole 251 of the printed circuit board 250 to be coupled. The light guiding unit 420 is made of a material including polymethylmethacrylate (PMMA) or polycarbonate (PC) having high strength and not easily being deformed or broken and having good transmittance.

The light guide portion 421 includes one or more light leakage preventing grooves 425 formed along the edge of the emission surface, and an accommodation groove 424 formed on the entrance surface to accommodate at least a portion of the second light source unit 410. . The light leakage preventing groove 425 may be penetrated or recessed in the light guide portion 421 in a direction perpendicular to the emission surface.

As shown in FIG. 3, the light leakage preventing groove 425 is a side surface of the light guide portion 421 where light flowed into the light guide portion 421 from the second light source unit 410 using Snell's low. Suppresses the leakage of light so that all light is emitted to the exit surface as much as possible. According to Snell's law, when light travels from a large refractive index material to a small material, it is not easily transmitted and total reflection is likely to occur. That is, when the light leakage preventing groove 425 is formed along the edge of the exit surface of the light guide portion 421, light directed toward the side of the light guide portion 421 is less than the light guide portion 421. Because it is in contact with the atmosphere inside, it becomes easy to be total reflection and cannot leak out.

In addition, the light guide portion 421 has a predetermined pattern 426 formed at a portion of the opposite surface of the emission surface from the second light source unit 410 at a predetermined distance. That is, a pattern is not formed on a part of the surface opposite to the emission surface close to the second light source unit 410. The length of the portion where the pattern is not formed on the opposite side of the exit surface is set so that light incident on the incident surface is uniformly spread in the light guide portion 420 by Snell's law.

As shown in FIG. 4, the light blocking film 428 may be covered along edges of the second optical sheets 430 and the light guide portion 421 accommodated in the storage space formed by the side wall portion 422. The reflective film 429 may be disposed on at least one side of the side surfaces of the unit 420 except for the emission surface of the light guide unit 421. Here, the reflective film pattern may be printed instead of the reflective film 429. The light blocking film 428 and the reflective film 429 may suppress light leakage to the periphery of the light guide unit 420 to reduce the loss of light. In addition, the light blocking film 428 may be formed of a material including a pressure sensitive adhesive (PSA), and may prevent lifting of the optical sheets 420 accommodated in the storage space of the light guide unit 420.

The second optical sheet 430 has the same structure as the first optical sheet 330 of the first backlight assembly 300 described above, and the reflector 440 is a reflective sheet of the first backlight assembly 300. Unlike 330, it is directly mounted on the printed circuit board 250, but has the same operation and effect as the reflective sheet 330.

In one embodiment according to the present invention, only the second light source unit 410 is mounted on the printed circuit board 250, and the reflective film 253 is also formed only around the second light source unit 410, which is merely according to the present invention. The structure and arrangement of the display device 10 are for illustrative purposes, and the present invention is not limited thereto. Therefore, the structure according to the present invention may be applied to the first backlight assembly 300 including the first light source unit 310, and the structure and arrangement of the display device 10 may also be variously modified.

As described above, in the display device according to the present invention, the light source unit is directly mounted on the printed circuit board, thereby simplifying the assembly process.

In addition, the reflection film is formed on the printed circuit board around the light source unit to suppress the loss of light that may occur before the light emitted from the light source unit reaches the place where the reflector is formed, thereby improving the luminance.

It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the following claims.

Claims (5)

A main display panel and a sub display panel for displaying an image; A first light source unit supplying light to the main display panel; A second light source unit supplying light to the sub display panel; A mold frame accommodating the main display panel and the first light source unit; A bottom chassis disposed under the mold frame; A printed circuit board on which the second light source unit is mounted and a reflective film is formed around the second light source unit; And A light guide portion for guiding light emitted from the second light source unit to the sub display panel, the light guide portion having an incident surface facing the second light source unit and an emission surface facing the sub display panel; A light guide unit having a sidewall portion forming a storage space for accommodating the sub display panel, The printed circuit board is positioned below the bottom chassis, and the sub display panel and the second light source unit are located opposite to the side where the bottom chassis is located with respect to the printed circuit board. And the printed circuit board transmits a driving signal to the main display panel and the sub display panel. The method of claim 1, The reflective film is formed by a silk coating. The method of claim 1, The reflective film is made of a material containing silver paste (Ag paste). The method of claim 1, The light guide unit is coupled to the printed circuit board, And a reflective plate mounted on at least a portion of the printed circuit board coupled to the light guide unit. The method of claim 1, The first light source unit or the second light source unit includes a light emitting diode.

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