KR100765145B1 - Liquid crystal display device - Google Patents

Abstract

Disclosed are a liquid crystal display device and a method of manufacturing a reflecting plate capable of preventing the reflection of the reflecting plate. The reflecting plate is stretched in a first direction and a second direction perpendicular to the first direction when viewed in a plane, and is elongated in a second direction having a lower elongation than the first direction, and then heat-treated at a predetermined temperature. Thereafter, the reflecting plate is cut in the second direction and disposed on the rear surface of the light guide plate such that the second direction is parallel to the longitudinal direction of the light source. Therefore, the difference in thermal expansion rate between one end of the light source of the reflection plate is installed and the other end facing the one end is minimized, so that the difference of the thermal expansion rate between the one end and the other end is caused. The phenomenon can be prevented.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

1 is an exploded perspective view of a conventional liquid crystal display device.

2 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating in detail the structure of the reflector shown in FIG. 2.

4 is a configuration diagram illustrating a stretching process of the reflector shown in FIG. 3.

5 and 6 are graphs showing thermal characteristics according to the stretching direction of the reflector shown in FIG. 2.

7 and 8 are graphs showing thermal characteristics of the light incidence part and the light incidence part of the reflector shown in FIG.

9 is a flowchart illustrating a manufacturing process of a reflecting plate according to another exemplary embodiment of the present invention.

FIG. 10 is a graph illustrating thermal characteristics of a reflector formed by the manufacturing process of FIG. 9.

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method for manufacturing a reflective plate that can prevent the phenomenon of the reflection plate.

Recently, with the development of the technology of the information processing apparatus, the development of the technology of the display apparatus for interfacing so that the user can recognize the data processed in the information processing apparatus has been made.

As a display device, a liquid crystal display device having a light weight, a small size, and a function such as full-color and high resolution is widely used. The liquid crystal display device is a display device for converting a change in the optical properties of the liquid crystal cell into a visual change.

1 is an exploded perspective view of a conventional liquid crystal display device.

Referring to FIG. 1, the liquid crystal display device 60 includes a liquid crystal display panel 20 for displaying an image. The liquid crystal display panel 20 includes a TFT substrate 21a, a color filter substrate 21b positioned on the TFT substrate 21a, and a liquid crystal (not shown) injected between the two substrates 21a and 21b. do.

Since the liquid crystal display panel 20 does not emit light by itself, light is supplied from the backlight assembly 30 attached to the rear surface of the liquid crystal display panel 20 to display an image. The backlight assembly 30 plays an important role in determining screen brightness and display characteristics of the liquid crystal display 60.

The backlight assembly 30 includes a lamp unit 31 for generating light, a light guide unit 32 for guiding light from the lamp unit 31, and the lamp unit 31 and the light guide unit 32. It includes a mold frame 40 for receiving the.                         

The lamp unit 31 is provided at one side of the lamp 31a for generating light and the lamp 31a to reflect the light from the lamp 31a to the light guide unit 32, and the lamp 31a. It consists of a lamp cover 31b that serves to cover the.

The light guide unit 32 is provided at one side of the lamp unit 31, and a light guide plate for guiding light from the lamp 31 to the liquid crystal display panel 20 under the liquid crystal display panel 20. 32a is provided. In addition, an optical sheet 33 for providing light diffused to the liquid crystal display panel 20 by uniformly diffusing the light emitted from the light guide plate 32a and provided on the upper surface of the light guide plate 32a. A reflection plate 34 is further provided to reflect the light leaked from the light guide plate 32a toward the liquid crystal display panel 20.

The lamp unit 31 and the light guide unit 32 configured as described above have an upper surface open and are housed in a mold frame 40 having a rectangular box shape to be fixedly supported. A top chassis having an upper and lower openings having an upper and lower surfaces to be coupled to the upper part of the liquid crystal display panel 20 so as to face the mold frame 40 to fix the liquid crystal display panel 20 to the mold frame 40. 50 is provided.

As shown in FIG. 1, the reflecting plate 34 is formed in a plate shape of a rectangular parallelepiped corresponding to the size of the light guide plate 32a. The reflector 34 is drawn in a predetermined direction by an external force. Specifically, the reflector plate 34 is elongated in a first direction A and in a second direction B perpendicular to the first direction A when viewed in a plan view. At this time, the reflecting plate 34 is elongated at a higher elongation rate in the second direction B than when it is elongated in the first direction A. FIG.

The reflective plate 34 is provided at one side of the lamp unit 31 such that the longitudinal direction of the lamp unit 31 and the first direction A are parallel to each other.

However, when heat is applied to the reflector 34, the reflector 34 expands to a certain temperature by the heat and passes a certain temperature (inflection point), and then contracts. Then, the contraction rate is further increased as the temperature increases.

As the liquid crystal display 60 is enlarged, the temperature of the light incident portion where the lamp unit 31 of the reflective plate 34 is installed exceeds the temperature of the inflection point, so that the contraction of the light incident portion of the reflective plate 34 is reduced. Occurs. At this time, the temperature of the light facing portion facing the light incident portion side is lower than that of the light incident portion side, but is still expanded because the temperature is continuously rising.

Therefore, the light incident part side contracts, and the light incident part side expands, so that the shape of the reflective plate 34 is deformed. As described above, the shape of the reflective plate 34 is deformed, thereby causing a dent of the reflective plate 34, and the display characteristic of the liquid crystal display 60 is reduced due to the dent.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of preventing the withdrawal of the reflecting plate.

Still another object of the present invention is to provide a method of manufacturing a reflector that can prevent the withdrawal of the reflector.

According to an aspect of the present invention, there is provided a liquid crystal display device including a light source for generating light, a light guide plate provided at one side of the light source, and a first direction and the first direction when viewed in plan view. A backlight having a reflecting plate which is perpendicular to the second direction and is elongated in a second direction having a relatively smaller elongation than the first direction, and is heat-treated to a predetermined temperature and disposed on a rear surface of the light guide plate to reflect light leaked from the light guide plate And a display unit for receiving light from the backlight assembly and displaying an image.

In this case, the reflector is heat-treated for a predetermined time at a temperature of 100 ~ 130 ℃.

In addition, the reflector may be cut in the second direction and disposed on the rear surface of the light guide plate such that the second direction is parallel to the longitudinal direction of the light source.

Method for manufacturing a reflector according to the present invention for achieving the above object is a) stretching the reflector in a first direction and a second direction perpendicular to the first direction and less elongation than the first direction, b) Heat treating the reflector to a predetermined temperature; and c) cutting the reflector.

In addition, the method of manufacturing the reflector further includes coating the reflector with aluminum.

In this case, the heat treatment of the reflector is performed for a predetermined time at a temperature of 100 ~ 130 ℃.

In addition, the reflector is cut parallel to the second direction.                     

According to the liquid crystal display device described above, the reflecting plate is stretched in the first direction and in the second direction perpendicular to the first direction in plan view, and then heat-treated at a predetermined temperature. Thereafter, the reflecting plate is cut in the second direction having the smaller elongation among the first and second directions, and is disposed on the rear surface of the light guide plate such that the second direction is parallel to the longitudinal direction of the light source.

Therefore, the difference in thermal expansion rate between one end of the light source of the reflection plate is installed and the other end facing the one end is minimized, so that the difference of the thermal expansion rate between the one end and the other end is caused. The phenomenon can be prevented.

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

2 is a perspective view schematically showing a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the liquid crystal display device 600 includes a liquid crystal display panel 200 for displaying an image and a backlight for supplying light from the lower portion of the liquid crystal display panel 200 to the liquid crystal display panel 200. An assembly 400.

The liquid crystal display panel 200 includes a TFT substrate 212, a color filter substrate 214 positioned on the TFT substrate 212, and a liquid crystal (not shown) injected between two substrates 212 and 214. do. In the TFT substrate 212, a thin film transistor that performs a switching role is formed in a matrix form, a gate line is connected to a gate electrode of each thin film transistor, a data line is connected to a source electrode, and a pixel electrode is connected to a drain electrode. Is formed.                     

The color filter substrate 214 is formed with an RGB pixel which is a color pixel for displaying an image. Therefore, the light transmitted through the liquid crystal is expressed in a predetermined color through the RGB pixel. In addition, a common electrode is formed on the front surface of the color filter substrate 214. Therefore, when a voltage is applied to the liquid crystal display panel 200, an electric field is formed between the common electrode and the pixel electrode of the thin film transistor to change the arrangement of liquid crystals therebetween.

The backlight assembly 300 is provided on a lamp unit 310 in which light is generated, the light guide unit 320 and the lamp unit for guiding light from the lamp unit 310. A mold frame 400 for accommodating the 310 and the light guide unit 320 is provided.

The lamp unit 310 is provided on a lamp 311 for generating light and on one side of the lamp 311 to cover the lamp 311, and the light generated from the lamp 311 to the light guide plate 320. And a lamp cover 312 for reflecting to the side.

In addition, the light guide unit 320 is provided at one side of the lamp unit 310 and includes a light guide plate 321 for guiding light incident from the lamp unit 310 to the liquid crystal display panel 200. Optical sheets 330 are provided on the light guide plate 321 to uniformly diffuse the light emitted from the light guide plate 321, and light leaked from the light guide plate 321 below the light guide plate 321. The reflective plate 340 for reflecting the light toward the liquid crystal display panel 200 is provided.

In this case, the reflector plate 340 is stretched in the third and fourth directions A and B to be described later, and then cut in the fourth direction B so that the fourth direction B is the lamp unit ( It is disposed on the rear surface of the light guide plate 321 to be parallel to the longitudinal direction of the 310. At this time, the elongation of the fourth direction (B) is relatively smaller than the elongation of the third direction (A).

The lamp unit 310 and the light guiding unit 320 configured as described above have an upper surface open and are housed in a mold frame 400 having a rectangular box shape and are fixedly supported. Specifically, the lamp unit 310 is accommodated in the storage space formed on one side of the mold frame 400, the reflecting plate 340 is first stored on the bottom surface, and then the light guide plate 320 and the optical sheets ( 330 are sequentially received.

A top chassis having an upper and lower openings having an upper and lower surfaces to be coupled to the upper part of the liquid crystal display panel 200 to face the mold frame 400 so as to fix the liquid crystal display panel 200 to the mold frame 400. 500 is provided. The top chassis 500 covers the effective display area of the liquid crystal display panel 200 so that the inner wall is in contact with the outer wall of the mold frame 400. Thus, the liquid crystal display device 600 is completed.

3 is a cross-sectional view showing in detail the structure of the reflector shown in FIG. 2, and FIG. 4 is a perspective view for explaining a drawing process of the reflector shown in FIG. 3.

3 and 4, the reflective plate 340 covers a surface of the PET layer 341 made of polyethylene terephthalate (PET) and both surfaces of the PET layer 341, with a predetermined shape of the voids 341a being oriented. It is made of a calcium carbonate layer 342 formed to be.

The reflective plate 340 performs a biaxial stretching process to orient the voids 341a to the PET layer 341. The reflecting plate 340 is elongated in a third direction A and a fourth direction B perpendicular to the third direction A when viewed in a plan view. At this time, the elongation in the third direction (A) is higher than the elongation in the fourth direction (B). More specifically, the elongation in the third direction A is about twice the elongation in the fourth direction B.

5 and 6 are graphs showing thermal characteristics according to the stretching direction of the reflecting plate. 7 and 8 are graphs showing thermal characteristics of respective parts of the reflector. 5 is a thermal characteristic graph I along the third direction, and FIG. 6 is a thermal characteristic graph II along the fourth direction.

Referring to FIG. 5, when the reflector is stretched in the third and fourth directions A and B and is subjected to a predetermined heat, the reflector is expanded by heat applied from about 0 ° C. to 70 ° C., and the temperature of 70 ° C. After passing, it contracts gradually. In this case, as the temperature of the heat applied to the reflector 340 increases, the shrinkage of the reflector further increases. Specifically, the shrinkage of the reflective plate 340 from about 70 to 100 ℃ is about 30%.

Referring to FIG. 6, in the fourth direction B of the reflecting plate 340, it is similarly expanded by heat applied to about 0 ° C. to 70 ° C., and then gradually contracts after passing the temperature of 70 ° C. FIG. In this case, in the fourth direction, the expansion rate of the reflective plate 340 is relatively smaller from 0 ° C. to 70 ° C. than in the third direction, and the shrinkage ratio of the reflective plate 340 is also relatively low after 70 ° C. Specifically, the shrinkage ratio in the fourth direction B of the reflecting plate 340 between 70 ° C. and 100 ° C. is about 13.3, about 1/2 of the shrinkage ratio of the third direction A. FIG.

Accordingly, the reflecting plate 340 is stretched in the third and fourth directions A and B, and then cut in the fourth direction B, which has a relatively small expansion rate and shrinkage rate, that is, relatively less affected by heat. The fourth direction B is disposed on the rear surface of the light guide plate 321 so as to be parallel to the longitudinal direction of the lamp unit 310.

Referring to FIG. 7, thermal characteristic graphs III and IV of respective portions of the reflecting plate 340 along the third direction A are shown. That is, the thermal characteristic graph (III) of the light incident portion where the lamp unit 310 is installed and the light from the lamp unit 310 is incident and the thermal characteristic graph (IV) of the light facing portion facing the light incident portion are shown.

As shown in FIG. 7, the expansion ratio at the light incident portion of the reflector 340 is relatively higher than the expansion ratio at the light portion at each temperature. At this time, it is assumed that the position of the lamp unit 310 according to the temperature of the light incident portion and the light portion is quickly heated to a state of about 80 ℃, the light portion is in a state of about 70 ℃. The light incident portion is increased by 0.1% of the initial length (L) than the initial length (L), the light portion is increased by 0.05% of the initial length (L) than the initial length (L).

Therefore, a difference of about 0.05% of the initial length of the light incident portion and the light facing portion occurs. Due to such a difference in expansion ratio, a difference occurs in the length of the light incident portion and the large light portion, thereby causing a phenomenon in the reflecting plate.

Meanwhile, referring to FIG. 8, thermal characteristic graphs V and VI of respective portions of the reflecting plate 340 along the fourth direction B are shown. That is, the thermal characteristic graph V of the light incident part where the lamp unit 310 is installed and the light from the lamp unit 310 is incident and the thermal characteristic graph VI of the light facing part facing the light incident part are shown.                     

As shown in FIG. 8, the expansion ratio at the light incident portion side of the reflecting plate 340 is almost the same as the expansion ratio at the light portion at each temperature. At this time, it is assumed that the position of the lamp unit 310 according to the temperature of the light incident portion and the light portion is quickly heated to a state of about 80 ℃, the light portion is in a state of about 70 ℃. The light incident portion and the light facing portion are each increased by 0.1% of the initial length (L) than the initial length (L).

Therefore, the difference in expansion rate according to the temperature between the light incident portion and the light facing portion is hardly generated.

That is, the reflecting plate 340 is stretched in the third and fourth directions A and b, and then cut in the fourth direction B to lengthen the fourth direction B and the lamp unit 310. By being disposed on the rear surface of the light guide plate 321 so that the directions are parallel, the difference in expansion ratio due to the difference in the heating time of the light incident portion and the large light portion of the reflective plate 340 is minimized.

9 is a flowchart illustrating a manufacturing process of a reflecting plate according to another exemplary embodiment of the present invention, and FIG. 10 is a graph for explaining thermal characteristics of the reflecting plate that has been processed in FIG. 9.

9 and 10, the reflective plate 340 performs a biaxial stretching process to orient the voids 341a to the PET layer 341 (S100). The reflecting plate 340 is elongated in a third direction A and a fourth direction B perpendicular to the third direction A when viewed in a plan view. At this time, the elongation in the third direction (A) is higher than the elongation in the fourth direction (B).

After the stretching process, the reflector plate 340 is subjected to a heat treatment process (S200). The reflective plate 340 is subjected to a heat treatment process at a temperature of 100 ~ 130 ℃. More specifically, the heat treatment process is performed for 60 seconds at a temperature of 120 ℃.

After the reflective plate 340 is cut in the third or fourth directions A and B (S300), the third or fourth directions A and B are the lamp units 310. It is disposed on the lower surface of the light guide plate 320 to be parallel to the longitudinal direction of (S300). In this case, the reflective plate 340 is preferably cut in the fourth direction B, which has a relatively smaller elongation than the third direction, and then the fourth direction B is parallel to the longitudinal direction of the lamp unit 310. Is arranged to.

On the other hand, the cut reflector 340 is coated with aluminum (Al).

The completed reflector 340 has a thermal characteristic graph shown in FIG. 10 in the third direction A. FIG. That is, the reflecting plate 340 is uniformly expanded without a section contracted by the heat applied through the heat treatment process.

In this case, the process of heat-treating the reflective plate 340 may be performed immediately after the stretching process of the reflective plate 340 is completed, as described above, and after the reflective plate 340 is completed, the liquid crystal display device 600 module It may be used by performing a heat treatment process immediately before assembling.

According to the above-described method for manufacturing a liquid crystal display and a reflecting plate, the reflecting plate is stretched in a first direction and a second direction perpendicular to the first direction and smaller in elongation than the first direction when viewed in plan view. Heat treated at temperature. Thereafter, the reflector is cut in the second direction and disposed on the rear surface of the light guide plate such that the second direction is parallel to the longitudinal direction of the light source.

Therefore, the difference in thermal expansion rate between one end of the light source of the reflection plate is installed and the other end facing the one end is minimized, so that the difference of the thermal expansion rate between the one end and the other end is caused. The phenomenon can be prevented.

Although described with reference to the examples, those skilled in the art can understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention described in the claims below. There will be.

Claims (7)

A light source for generating light, light guide means for guiding the light, and a second direction perpendicular to the first direction and the first direction and smaller in elongation than the first direction when viewed in a plane A backlight assembly each of which is stretched and heat-treated to a predetermined temperature, and is disposed on a rear surface of the light guiding means and includes a reflecting plate for reflecting light leaked from the light guiding means; And And a display unit for receiving light from the backlight assembly and displaying an image. The liquid crystal display device according to claim 1, wherein the reflecting plate is heat-treated at a temperature of 100 to 130 ° C. for a predetermined time. The liquid crystal display device according to claim 1, wherein the reflecting plate is cut in the second direction so that the second direction is parallel to the longitudinal direction of the light source. a) stretching the reflecting plate in a first direction and in a second direction perpendicular to the first direction and having a smaller elongation relative to the first direction; b) heat treating the reflector to a predetermined temperature; And and c) cutting the reflector. The method of claim 4, wherein the heat treatment of the reflector is performed at a temperature of 100 to 130 ° C. for a predetermined time. The method of claim 4, wherein the reflector is cut parallel to the second direction. The method of claim 4, further comprising coating the reflector with aluminum.

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