KR20070051034A - Back light for liquid crystal display device and liquid crystal display module using the same - Google Patents

Abstract

The present invention relates to a backlight for a liquid crystal display device and a liquid crystal display module using the same. More particularly, the present invention relates to a backlight and a liquid crystal display module using the same, which can solve a relative decrease in luminance appearing at an end of a fluorescent lamp.

Specifically, the present invention is a light guide plate; A fluorescent lamp arranged along at least one side of the light guide plate; A backlight for a liquid crystal display device comprising an EL sheet partially interposed between the fluorescent lamp and at least one side of the light guide plate to emit light toward at least one side of the light guide plate, and implements a liquid crystal display device using the same.

As a result, the luminance reduction relative to the end of the fluorescent lamp covered by the clip or the like is compensated by the EL sheet to realize even luminance over the entire area of the light guide plate, and improved image quality can be realized.

Description

Back light for liquid crystal display device and liquid crystal display module using the same}

1 is an exploded perspective view of a part of a general liquid crystal display module.

2 is a schematic plan view of a part of a general liquid crystal display module.

3 is an exploded perspective view of a liquid crystal display module according to the present invention.

4 is an enlarged perspective view of a part of a liquid crystal display module according to the present invention;

5 is a cross-sectional structure diagram of an EL sheet;

6 is a schematic plan view of a part of a liquid crystal display module according to the present invention;

7 and 8 are enlarged perspective views showing still another example of a part of a liquid crystal display module according to the present invention, respectively.

<Description of the symbols for the main parts of the drawings>

100: liquid crystal panel 102, 104: first and second substrate

106: TCP 108a, 108b: liquid crystal panel driver circuit

120: backlight 122: reflective sheet

130: light guide plate 140: fluorescent lamp

142 lamp holder 150 optical sheet

152: reverse prism sheet 156: diffusion sheet

160: Lamp Guide 170: Clip

180: EL sheet 200: support main

210: cover cover 220: top cover

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight for a liquid crystal display device and a liquid crystal display module using the same. More specifically, the present invention relates to a relative decrease in luminance occurring at an end of a fluorescent lamp. The present invention relates to a liquid crystal display backlight and a liquid crystal display module using the same.

In line with the recent information age, the display field for displaying images by electric signals has also been rapidly developed. In response, the flat panel display device (FPD) has advantages of thinning, light weight, and low power consumption. Liquid Crystal Display Device (LCD), Plasma Display Panel Device (PDP), Electroluminescence Display Device (ELD), Field Emission Display Device (FED) The lamp is introduced to replace the existing cathode ray tube (CRT) quickly.

Among them, the liquid crystal display device is excellent in moving image display and has a high contrast ratio, which is currently being used most actively in the fields of monitors and TVs, which are used for optical anisotropy, which is inherent in liquid crystals. The principle of image realization using polarization shows that liquid crystals have a thin and long molecular structure and have an optical anisotropy having an orientation in an array and an arrangement direction of molecules depending on their size when placed in an electric field. It is polarized.

In general, a liquid crystal display device includes a liquid crystal panel in which two substrates having transparent electrodes are formed on a surface facing each other with a liquid crystal layer interposed therebetween, and a back light for supplying light from the rear side thereof. In addition, the array of liquid crystal molecules is changed by an electric field between two electrodes of the liquid crystal panel to generate a transmittance difference, and the difference in transmittance of the liquid crystal panel is projected to the outside with light emitted from the backlight to display a desired image.

Recently, an active matrix type, in which pixels, which are basic units of image expression, are arranged in a matrix on a liquid crystal panel and individually controlled by switching elements such as thin film transistors (TFTs), have color reproducibility. Excellent for displaying videos and videos, it is widely used.

In addition, as a light source of the backlight of the liquid crystal display device, a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) is generally used. According to the light source (side light type) and direct type (direct type), the light metering type of the light guide panel (Light Guided Panel: LGP) is refracted into the liquid crystal panel, whereas the latter direct type supplies light by directly placing a plurality of light sources directly on the back of the liquid crystal panel.

On the other hand, since the liquid crystal display device mobilizes various mechanical elements for the integration of the liquid crystal panel and the backlight, hereinafter referred to as a liquid crystal display module, the accompanying Figure 1 is an exploded perspective view of the main part of the general metering liquid crystal display module As the liquid crystal panel 10 and the backlight 20 provided on the back thereof, it may be confirmed.

First, the liquid crystal panel 10 includes first and second substrates 12 and 14 bonded to each other with the liquid crystal layer interposed therebetween.

In addition, the backlight 20 includes a light guide plate 30 positioned side by side on the rear surface of the liquid crystal panel 10, a fluorescent lamp 40 disposed along one side thereof, and a plurality of light interposed between the light guide plate 30 and the liquid crystal panel 10. It includes a sheet of optical sheet 50, and in addition to the upper and lower sides of the remaining fluorescent lamp 40 except for the direction facing one side so that the light emitted from the fluorescent lamp 40 is concentrated on one side of the light guide plate 30 It includes a lamp housing 44 which guides three directions and a reflective sheet 60 in close contact with the rear surface of the light guide plate 30 to minimize light loss.

In addition, both ends of the fluorescent lamp 40 are wrapped by a pair of clips 46 with the lamp holder 42 covered to prevent damage caused by the collision between the fluorescent lamp 40 and the light guide plate 30. The clip 46 for this purpose is a lamp including both ends of the fluorescent lamp 40 bent at both ends parallel to each other about an intermediate portion interposed between the lamp holder 42 and one side of the light guide plate 30. The form in which the holder 42 is wrapped in three directions of upper and lower sides is shown.

Therefore, the light emitted from the fluorescent lamp 40 is incident on one side of the light guide plate 30 by the lamp housing 44 and then refracted toward the liquid crystal panel 10, and passes through the plurality of optical sheets 50. It is processed in the form of a more uniform surface light source during the process.

In this case, as shown in the drawing, the light guide plate 30 formed by forming a row of first prism patterns 32 in a direction substantially perpendicular to the fluorescent lamp 40 toward the reflective sheet 60 is called a prism light guide plate. In this case, a diffusion layer 34 is formed on the upper surface of the light guide plate 30 facing the liquid crystal panel 10, and the optical sheet 50 has an inverted prism sheet 52 on the light guide plate 30 side and a liquid crystal panel 10 side. A diffusion sheet 56 is included, and a second prism pattern 54 in a direction crossing the first prism pattern 32 is formed on the rear surface of the inverted prism sheet 52. Therefore, in this case, the light emitted from the fluorescent lamp 40 is collected and refracted by the first prism pattern 32 of the light guide plate 30, and then diffused during the process of passing through the diffusion layer 34, and again, an inverse prism sheet ( The light is condensed and refracted by the second prism pattern 54 of FIG. 52, and then diffused by the diffusion sheet 56, thereby improving brightness and improving uniformity.

However, the above-described general liquid crystal display device exhibits a relative decrease in luminance at both ends of the fluorescent lamp 40, and this partial luminance difference is reflected on the display image, thereby degrading image quality. The cause can be found in the pair of clips 46 fitted to both ends of the fluorescent lamp 40, in particular, this partial luminance difference is exacerbated in the case of the prism light guide plate.

That is, FIG. 2 is a schematic plan view of a part of the general liquid crystal display module described above, and includes a light guide plate 30, a fluorescent lamp 40 disposed at one edge thereof, and a pair of clips fitted at both ends thereof. 46 is shown.

As can be seen in the drawing, since a pair of clips 46 are fitted at both ends of the general fluorescent lamp 40, relative luminance decreases to cover the light of the corresponding part. Particularly, the first fluorescent lamp 40 is substantially perpendicular to the fluorescent lamp 40. When the prism pattern 32 is formed on the rear surface of the light guide plate 30, that is, when the prism light guide plate is used, light incident on one side thereof is adjacent to each other while traveling along the arrangement direction of the first prism pattern 32. The light is condensed and refracted in a state where light diffusion with the pattern is suppressed, and as a result, both edges of the light guide plate 30 corresponding to the fastening portion of the clip 42 at both ends of the fluorescent lamp 40 are relatively low. The luminance is shown.

In addition, the partial luminance decrease is transparent to the display screen, which is a direct cause of the image quality degradation such as partial luminance unevenness.

Accordingly, the present invention has been made to solve the above problems, and provides a backlight for a liquid crystal display device that can solve the relative decrease in luminance appearing at the clip fastening portion of both ends of the fluorescent lamp, and also using the backlight Accordingly, an object of the present invention is to provide a liquid crystal display device capable of realizing improved image quality.

In order to achieve the above object, the present invention is a light guide plate; A fluorescent lamp arranged along at least one side of the light guide plate; Provided is a backlight for a liquid crystal display device comprising an EL sheet partially interposed between the fluorescent lamp and at least one side of the light guide plate to emit light toward at least one side of the light guide plate.

At this time, the EL sheet further comprises a clip surrounding the end of the fluorescent lamp, characterized in that the EL sheet is interposed between the clip and at least one side of the light guide plate, in this case is inserted into the end of the fluorescent lamp is wrapped together by the clip May further include a lamp holder. The clip may further include: an intermediate portion interposed between at least one side surface of the light guide plate and an end portion of the fluorescent lamp; And both end portions bent in the same direction from both ends of the intermediate portion with the end of the fluorescent lamp interposed therebetween, wherein the EL sheet is directed toward the outer surface of the middle portion of the clip facing at least one side of the light guide plate. It is characterized in that attached.

In addition, the LE sheet, the fluorescent layer; An anode and a cathode electrode in close contact with both surfaces of the fluorescent layer; It is characterized in that it comprises a transparent synthetic resin film in close contact with the outer surface of the anode and the cathode electrode laminated.

In addition, the liquid crystal display backlight according to the present invention includes a reflection sheet covering the rear surface of the light guide plate; An optical sheet covering an upper surface of the light guide plate; And a lamp housing for wrapping and guiding the fluorescent lamp in a state in which a direction toward at least one side of the light guide plate is opened. The light guide plate may include: a first prism pattern formed on a rear surface of the light guide plate and crossing the alignment direction of the fluorescent lamp; And a diffusion layer formed on an upper surface, in which case the optical sheet has an inverted prism formed with a second prism pattern in a direction intersecting the first prism pattern on a rear surface of the light guide plate and facing the light guide plate. Sheets; And a diffusion sheet positioned on an upper surface of the reverse prism sheet.

In another aspect, the present invention provides a liquid crystal display module using a backlight according to the above description, comprising: a liquid crystal panel mounted on the optical sheet; A support main bordering an edge of the liquid crystal panel and the backlight; A cover bottom covering the rear surface of the reflective sheet; Provided is a liquid crystal display module including a top cover that borders a front edge of the liquid crystal panel.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

3 is an exploded perspective view of a liquid crystal display module according to the present invention, and includes a liquid crystal panel 100 and a backlight 120 that are stacked up and down, and the edges thereof support a rectangular main frame. A cover bottom (210) serving as a bottom surface covering the rear surface of the backlight 120 in a state where the 200 is bordered together and a top cover (220) that borders the front edge of the liquid crystal panel 100 are supported. It shows a structure that is coupled to and integrated in the front and rear room through the main 200.

Look at each one in more detail.

First, the liquid crystal panel 100 includes a pair of first and second substrates 102 and 104 bonded to each other with a liquid crystal layer interposed therebetween as a part that plays a key role in image expression.

Although not clearly shown in the drawings, a plurality of gate lines and data lines intersect the inner surface of the first substrate 102 called a lower substrate or an array substrate to define pixels, and thin film transistors are formed at each intersection point. And a one-to-one correspondence with pixel electrodes mounted on each pixel. In addition, an inner surface of the second substrate 104 called an upper substrate or a color filter substrate may correspond to each pixel, for example, a color filter of R, G, and B colors and borders each of the gate and data lines. A black matrix covering non-display elements such as a thin film transistor is provided, and a common electrode covering them is provided.

In addition, the liquid crystal panel driving circuits 108a and 108b are connected through at least one edge of the liquid crystal panel 100 through a TCP (Tape Carrier Package) 106, and the side or cover bottom of the support main 200 in the modularization process. The liquid crystal panel driver circuits 108a and 108b each have a gate driver circuit that scans and transmits the on / off signal of the thin film transistor to the gate line. 108a) and a data driver circuit 108b for transmitting an image signal to a data line, and may be connected to two adjacent edges of the liquid crystal panel 100, respectively.

As a result, when the thin film transistor selected for each gate is turned on by the on / off signal of the gate driver circuit 108a which is scanned and transmitted, the signal voltage of the data driver circuit 108b is applied to the corresponding pixel electrode through the data line. The direction of the liquid crystal molecules is changed by the vertical electric field between the pixel electrode and the common electrode, thereby indicating the transmittance difference.

In addition, the backlight 120 is provided on the rear surface of the liquid crystal panel 100 to supply light such that the difference in transmittance is expressed to the outside, which is a white or silver reflective sheet 122 covering the inner surface of the cover bottom 210. And a light guide plate 130 mounted on an upper portion thereof, a fluorescent lamp 140 disposed inside the edge of the support main 200 to face at least one side surface 136 of the light guide plate 130, and a light guide plate 130. It includes a plurality of optical sheets 150 interposed between the liquid crystal panel 100.

In addition, the light emitted from the fluorescent lamp 140 is concentrated on at least one side surface 136 of the light guide plate 130 facing it, so that the remaining fluorescent lamp 140 in the upper and lower sides except for the direction facing the at least one side surface 136. Lamp housings 160 that surround three directions are disposed together inside the edge of the support main 200, and end portions of the fluorescent lamps 140 to prevent breakage due to collision between the light guide plate 130 and the fluorescent lamps 140. The furnace is covered with a lamp holder 142 of a soft material such as silicon and at the same time the clip 170 is wrapped and protected, the clip 170 is mounted into the lamp housing 160 together with the fluorescent lamp 140.

Accordingly, the light emitted from the fluorescent lamp 140 concentrates at least one side surface 136 of the light guide plate 130 by the lamp housing 160 and refracts toward the liquid crystal panel 100, and is reflected from the reflective sheet 122. While passing through the plurality of optical sheets 150 with the light is processed to a high quality of uniform brightness is irradiated to the liquid crystal panel 100.

In this case, the light guide plate 130 of the liquid crystal display module according to the present invention preferably has a first prism pattern (1) in a direction substantially perpendicular to the fluorescent lamp 140 on the rear surface facing the reflective sheet 122. A prism light guide plate having a 132 formed in a stripe shape may be used. In this case, a diffusion layer 134 is formed on an upper surface of the light guide plate 130. The optical sheet 150 may include a reverse prism sheet 152 on the prism light guide plate 130 and a diffusion sheet 156 on the liquid crystal panel 100. A second prism pattern 154 in a direction crossing the first prism pattern 132 is formed.

Meanwhile, in the liquid crystal display module according to the present invention, the EL sheet 180 is attached to the outer surface of the clip 170 that covers and protects the lamp holder 142 covered with the corresponding portion including the end of the fluorescent lamp 140. It features.

4 is an exploded perspective view showing an enlarged clip 170 according to the present invention. A part of the lamp holder 142, the lamp housing 160, and the light guide plate 130, which are fitted, is shown together, and the clip 170 may include at least one side 136 and the lamp holder 142 of the light guide plate 130. Both ends 172 and 174 may be bent side by side with the middle portion 172 interposed therebetween to wrap the lamp holder 142 including the end of the fluorescent lamp 140 in three directions of up and down inside. have.

In other words, for convenience, the direction toward the one side 136 of the light guide plate 130 is an inner side, and the clip 170 covers the end of the fluorescent lamp 140 together with the lamp holder 142 in three directions of upper and lower sides. The lamp housing 160 may be accommodated in the housing 160, and the lamp housing 160 may cover the end portions of the lamp holder 142 including the clip 170 and the fluorescent lamp 140 in three directions of up and down.

As a result, the middle portion 172 of the clip 170 is exposed toward one side 136 of the light guide plate 130, and the EL sheet 180 is attached thereto.

In this case, the EL sheet 180 is a neutral exciton formed by coupling holes and electrons through an emission layer between an anode electrode supplying holes and a cathode electrode supplying electrons. When the exiton is changed from the excited state to the ground state, a light emission phenomenon is used, and as shown in FIG. After implementation, it refers to a product laminated by interposing into a transparent insulating film 188 such as PET. When a constant voltage is applied to the anode electrode 182 and the cathode electrode 186 of the EL sheet, light is emitted. Thus, either one of the two electrodes 182 and 186 is transparent, and light can be irradiated in a desired direction. It is thin, easy to handle, and has excellent workability such as folding and winding, and is widely used in automobile dashboards and advertisements.

Referring to FIG. 4 again, the liquid crystal display module according to the present invention is attached to the outer surface of the clip 170 covering the end of the fluorescent lamp 140, the EL sheet 180 is attached to the relative decrease in the luminance appearing in the corresponding portion By removing the phenomenon, it shows the effect of suppressing the collision between the light guide plate 130 and the fluorescent lamp 140 by the clip 170 and the damage of the fluorescent lamp 140 as well as blocking the light emitted from the fluorescent lamp 140 by the clip 170. As a result, the partial luminance deterioration phenomenon appeared in the corresponding portion is solved through the EL sheet 180 attached to the outer surface of the clip 170.

That is, FIG. 6 is a schematic plan view of a part of the liquid crystal display module according to the present invention, and includes a light guide plate 130, a fluorescent lamp 140 disposed at one edge thereof, and both ends of the fluorescent lamp 140. A pair of clips 170 is shown, which is an EL sheet 180 attached to the outer surface of the clip 170 at both ends of the clip 170, that is, at both ends of the fluorescent lamp 140. ) Light is emitted, and the light of the fluorescent lamp 140 is emitted from the other parts.

Therefore, preferably, when the luminance of the EL sheet 180 is adjusted to a level similar to that of the fluorescent lamp 140, a uniform luminance can be obtained over the entire surface of the light guide plate 130. In particular, the light guide plate 130 is a fluorescent lamp. The same effect can be expected even with a prism light guide plate which can hardly expect light diffusion between neighboring patterns by the first prism pattern 132 substantially perpendicular to 140. At this time, although not shown in detail in the drawings, the power supplied to the EL sheet 180 may be provided separately or may share the driving power and the inverter of the fluorescent lamp 140.

On the other hand, the attachment portion of the EL sheet 180 in the clip 170 according to the present invention can be adjusted according to the purpose, as shown in Figure 4 clip 170 facing one side 136 of the light guide plate 130 It can be easily expected that it is most advantageous in terms of light efficiency to attach to the outer surface of the middle portion 172), but according to the purpose, the EL sheet 180 is applied to the entire outer surface of the clip 170 as shown in FIG. It is also possible to attach.

8 is a view showing that the EL sheet 180 can be attached without difficulty even though the shape of the clip 170 is somewhat different, it may be easily understood without further explanation. In this case, the clip 170 The EL sheet 180 can be attached to the entire outer surface.

On the other hand, the technical idea of the present invention is not limited to the above description and various modifications are possible, even if there is no clip 170 as an example in the above description with reference to FIGS. 3 and 4 lampholder 142 or fluorescent lamp 140 Relative luminance decrease may occur due to an electrode (not shown), and in this case, the same effect may be expected by attaching the EL sheet 180 to the corresponding portion. In addition, depending on the purpose, the EL sheet 180 may be directly attached to one side 136 of the light guide plate 130.

That is, the core technical idea of the present invention uses the EL sheet 180 to compensate for partial luminance difference of the fluorescent lamp 140, and the EL sheet 180 is the fluorescent lamp 140 and the light guide plate 130. Any configuration may be interposed between at least one side 136 of the light guide plate 140 to emit light toward at least one side 136 of the light guide plate 140.

Therefore, there may be various modifications to satisfy this, but they all must belong to the present invention, it will be apparent to those skilled in the art upon reference to the following claims.

As described above, the backlight according to the present invention has an advantage of eliminating the relative luminance deterioration phenomenon appearing at the end of the fluorescent lamp.

Therefore, a high-quality surface light source having a uniform brightness over the entire light guide plate is supplied to the liquid crystal panel, and thus the image quality can be greatly improved.

Claims (10)

A light guide plate; A fluorescent lamp arranged along at least one side of the light guide plate; An EL sheet partially interposed between the fluorescent lamp and at least one side of the light guide plate to emit light toward at least one side of the light guide plate Backlight for a liquid crystal display device comprising a. The method of claim 1, Clip surrounding the end of the fluorescent lamp And the EL sheet is interposed between the clip and at least one side of the light guide plate. The method of claim 2, Lamp holder fitted to the end of the fluorescent lamp and wrapped together by the clip Backlight for a liquid crystal display device further comprising. The method of claim 2, The clip, An intermediate portion interposed between at least one side surface of the light guide plate and an end portion of the fluorescent lamp; Both end portions bent in the same direction from both ends of the intermediate portion with the end of the fluorescent lamp in between Backlight for a liquid crystal display device comprising a. The method of claim 4, wherein The EL sheet is, And a backlight attached to an outer surface of a middle portion of the clip facing at least one side of the light guide plate. The method of claim 1, The LE sheet, A fluorescent layer; An anode and a cathode electrode in close contact with both surfaces of the fluorescent layer; The transparent synthetic resin film adhered to the outer surfaces of the anode and the cathode and laminated together Backlight for a liquid crystal display device comprising a. The method of claim 1, A reflective sheet covering a rear surface of the light guide plate; An optical sheet covering an upper surface of the light guide plate; A lamp housing which surrounds and guides the fluorescent lamp in a state in which a direction toward at least one side of the light guide plate is opened; Backlight for a liquid crystal display device further comprising. The method of claim 7, wherein The light guide plate, A first prism pattern formed on a rear surface of the fluorescent lamp and intersecting with an arrangement direction of the fluorescent lamp; Diffusion layer formed on the upper surface Backlight for a liquid crystal display device comprising a. The method of claim 8. The optical sheet, An inverted prism sheet positioned on an upper surface of the light guide plate and having a second prism pattern in a direction intersecting the first prism pattern on a rear surface of the light guide plate; Diffusion sheet positioned on the reverse prism sheet Backlight for a liquid crystal display device comprising a. A liquid crystal display module using a backlight according to any one of claims 7 to 9, A liquid crystal panel seated on the optical sheet; A support main bordering an edge of the liquid crystal panel and the backlight; A cover bottom covering the rear surface of the reflective sheet; Top cover bordering the front edge of the liquid crystal panel Liquid crystal display module comprising a.

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