KR19980065999U - Backlight Structure of LCD - Google Patents

Abstract

The present invention relates to a backlight structure of a liquid crystal display device, which can reduce the weight of the LCD by directly transmitting light to the LCD panel using a lighter lens structure compared to the light guide plate, and also because light is directly incident on the lens structure to the LCD panel. The light efficiency can be increased.

Description

Backlight Structure of Liquid Crystal Display

The present invention relates to a backlight unit of a liquid crystal display device, and more particularly, to a backlight structure of a liquid crystal display device in which a microlens structure is installed around a lamp in order to increase the light efficiency of the liquid crystal display device and to realize a light weight. It is about.

Cathode ray tube (CRT), which is one of the display devices that are generally used, is mainly used for monitors such as TVs, measuring devices, and information erasing devices.However, due to the large weight and size of the CRT itself, the miniaturization and weight reduction of electronic products Can not respond actively to the needs of

In order to replace such CRTs, liquid crystal displays (LCDs), which have advantages of small size and light weight, have been actively developed, and recently, they have been developed enough to perform a role as flat panel displays.

In addition, unlike a CRT, an LCD is not a light emitting device in which a liquid crystal directly generates light, but a light receiving device that displays a screen by controlling the amount of light coming from the outside. Therefore, in order to irradiate light to the LCD panel, a separate light source, that is, a backlight device, must be used. Therefore, in order to improve the display quality of the LCD, the LCD itself is heavily dependent on the performance of the backlight device.

In general, LCD is mainly used as a display device of a portable computer such as a notebook. Since such portable computers are intended for portable and mobile use, they must be light and consume less power due to the limited capacity of the storage battery. Therefore, the backlight device, which is one of the main power consumption sources of the portable computer, has been mainly developed with the goal of thinning and low power consumption.

1 is an exploded cross-sectional view illustrating a general backlight structure.

A light guide plate 5 is provided on a front surface of a lamp 1 used as a light source of a liquid crystal display, and a silver plating is applied on the rear surface of the lamp to reflect the incident light and transmit the light to the light guide plate 5. The treated lamp holder 3 is located. In addition, a reflecting plate 7 capable of reflecting light is disposed below the light guide plate 5, a diffuser plate 9 is disposed above the light guide plate 5, and a prism sheet 11 is placed thereon. A protective film 13 is attached to the prism sheet 11 to protect the prism sheet 11 sensitive to scratches, and the LCD panel 15 is placed on the protective film 13.

The operation of the backlight device having such a structure will be described below.

Light emitted from the lamp 1 is incident directly on the light guide plate 5 on which the reflecting dot is printed or reflected on the lamp holder 3 surrounding the lamp and transmitted to the light guide plate 5. Some of the light incident on the light guide plate 5 is reflected to the upper surface of the light guide plate 5 as it is, but part of the light leaks to the bottom surface of the light guide plate 5 and is reflected by the reflective plate 7 and then travels again inside the light guide plate 5. . As such, the light reflected to the upper surface of the light guide plate 5 is uniformly diffused while passing through the diffuser plate 9, and the diffused light is collected by the prism sheet 11 and the luminance is increased. Light is then incident on each pixel of the LCD panel 15 so that a screen is displayed on the LCD panel 15.

However, since the light emitted from the lamp is not directly incident to the LCD panel but is incident to the LCD panel through the light guide plate and sheets, about 45% is lost while the light emitted from the lamp reaches the light guide plate and the light incident on the light guide plate is lost. There was a problem that the light efficiency is lowered because about 5% is lost to reach the LCD panel again.

In addition, the weight of the light guide plate of the backlight device used to irradiate light to the LCD panel is more than 50% of the total backlight device, and the thickness of the light guide plate is increased as the LCD panel requiring high brightness increases the weight of the LCD. there was.

Accordingly, an object of the present invention has been made in view of the above problems, to provide a backlight device structure of a liquid crystal display device to increase the light efficiency of the LCD panel and to reduce the weight of the LCD by installing a micro lens structure around the lamp.

1 is an exploded cross-sectional view illustrating a general backlight structure.

2 is a cross-sectional view schematically showing the structure of a backlight device according to the present invention.

3A is an enlarged cross-sectional view illustrating main parts of FIG. 2 and enlarged in FIG.

4a and 4b are views for explaining the shape of the lamp,

5 is a state diagram illustrating a state in which light passes through the lens structure.

In order to achieve the above object, the present invention provides a mold frame, a diffusion plate installed on an upper surface of the mold frame to diffuse incident light, an LCD panel installed on an upper surface of the diffusion plate, and displaying the information. A lamp structure installed at a side of a mold frame to emit the light, and a micro lens structure installed at the front of the lamp structure and dividing the LCD panel into a plurality of predetermined blocks to guide the light to the LCD panel so as to correspond to the predetermined blocks. Characterized in that it comprises a.

The backlight device according to the present invention is composed of a lamp, a micro lens structure, and a diffusion sheet.

Hereinafter, the structure of the backlight device according to the present invention will be described with reference to FIGS. 2 and 3, 4, and 5.

Figure 2 is a cross-sectional view schematically showing the structure of the backlight device according to the present invention, Figure 3a is an enlarged cross-sectional view of the main portion of the enlarged portion B of Figure 2 is a perspective view of the micro lens structure of Figure 3b, Figures 4a and 4b is a lamp Is a view for explaining the shape of, Figure 5 is a state diagram showing a state in which light passes through the lens structure.

As shown in FIG. 2, one side of the mold frame 110 is installed at a lamp 120 used as a light source of the LCD and a rear surface of the lamp 120, and an inner surface thereof is silver plated to reflect light emitted from the lamp 120. The lamp structure consisting of the lamp holder 121 is located.

In addition, a front surface of the lamp 120 is provided with a micro lens array 130 for guiding light emitted from the lamp 120. In addition, the reflector 111 is formed on the lower surface of the mold frame 110 except for the portion where the micro lens structure 130 is installed. The reflector is preferably formed by silver plating the lower surface of the mold frame 110. Or a silver plated reflector is installed on the lower surface of the mold frame 110.

In addition, a diffusion plate 140 for diffusing light incident from the microlens structure 130 is disposed on an upper surface of the mold frame 110, and an LCD panel for displaying information is provided on the upper surface of the diffusion plate 140. 150) is installed.

As shown in FIG. 3B, the micro lens structure 130 is installed at the front surface of the lamp 120 and formed to correspond to the longitudinal direction of the lamp structure 130. It is installed and is formed extending in the longitudinal direction of the lens fixing portion 131 and consists of a plurality of micro lenses 133 for guiding light to the LCD panel 150. Here, as shown in FIG. 3A, the cross-sectional shapes of the microlenses 133 pass through the microlenses 133 toward the LCD panel 150 according to a position arranged in the lens fixing part 131 in a fan shape. The amount of incident light is formed to be different from each other.

Referring to FIG. 4, the shape of the microlens 133a installed at the lowermost end of the lens fixing part 131 may have a diameter at the center of the diameter of the circle where A point and B point are connected as shown in FIG. 4A. If you draw a bisector l so that it is perpendicular, then the line segment AB is bisected. If an oblique line L is drawn from the end of the bisector l again to the point B, an arc R is formed at the upper end of the microlens 133a located on the LCD panel side, and an oblique line L having a constant slope is formed at the lower end of the microlens 133a positioned at the reflector side. do. As shown in FIG. 4B, the shape of the microlens 133b provided on the upper surface of the lowermost part moves the bisector l of 4a a predetermined length in the A direction to draw the bisector l ′ of FIG. 4B. Drawing an oblique line L 'from the end of the bisector l' to the point B, an R 'of the same curvature as the circular arc R is formed on the upper end of the microlens 133b located on the LCD panel side, and a lower end of the microlens 133b located on the reflecting side. An oblique line L having θ 'smaller than any angle θ formed in 3a is formed. As such, when the bisector is uniformly moved in the A direction and an oblique line is drawn at the end of the bisector, an arbitrary angle formed by the segments AB and BL becomes gradually smaller, and the length of the arc formed on the upper surface of the microlens 133 is also shortened. .

Here, preferably, the distance between the lower surface of the diffusion plate 140 and the lens fixing part 131 is about 0.7 mm, the thickness of the lens fixing part 131 is 2.3 mm, and the size of one microlens 133 is 15 μm. to be. In addition, the material of the lens fixing part 131 is a polymer that can transmit light, and the material of the micro lens 133 is preferably glass.

Meanwhile, the number of micro lenses 133 installed on the front surface of the lens fixing part 131 is calculated based on the 10.4 inch LCD panel 150 as follows. Here, the distance of the active area of the 10.4 inch LCD panel 150 is 212 mm, and the number of pixels formed in the effective screen area is about 640. Assuming that one microlens 133 can cover a distance of about 5 pixels, the screen effective area is divided into 128 blocks, and 128 microlenses 133 are also required. In addition, in order to install all 128 micro lenses 133 in the lens fixing part 131 of 2.3 mm, the micro lenses 133 should be formed to a size of about 18 μm. That is, one 18 µm lens can irradiate light to the 1.65 mm region.

The operation of the backlight device configured as described above is as follows.

The light emitted from the lamp 120 passes through the air (n0), the lens fixing part 131 of the polymer material (n1), and the microlens 133 of the glass material (n2) in order, and then again into the air (n0). The light is refracted several times during the divergence. This is caused by the fact that each medium is different from each other. As shown in FIG. 4, light incident to the lens fixing part 131 in the air n0 is refracted downward in the lens fixing part 131, and the lens Light incident from the fixing part 131 to the microlens 133 is refracted upward in the microlens 133. In addition, the light incident from the microlens 133 back into the air n0 is refracted upward or downward depending on the shape of the microlens 133. That is, as shown in FIG. 3A, light incident into the air n0 from the arc R with curvature of the microlens 133 is refracted toward the diffuser plate 140 in the upper direction and air n0 from the oblique line L without curvature. The incident light is refracted toward the reflecting part 111 in the downward direction. As a result, some of the light incident from the microlens 131 into the air n0 is refracted in the upper direction and in the lower direction because the light intensity of the LCD panel 150 near the lamp 120 is strong and the lamp is strong. This is because the intensity of the light of the LCD panel 150 at a distance from the 120 is weak, thereby decreasing the uniformity of the entire LCD panel 150. Therefore, as the microlenses 133 are installed closer to the LCD panel 150, the shorter the arc length that can deflect light toward the LCD panel, the shorter the amount of light that is deflected toward the LCD panel 150 adjacent to the lamp 120. By reducing the overall uniformity of the LCD panel 150 is improved.

As such, the light passing through the microlens 133 is partially directed to the reflector 111, and part of the light is incident on the LCD panel 150 according to the shape of the microlens 133. The light refracted in the upward direction in the microlens 133 is diffused by the diffused 140 and then directly incident on the LCD panel 150, and the light refracted in the downward direction is formed on the lower surface of the mold frame 110. The light is reflected by the reflector 111 and is incident to the LCD panel 150 far from the lamp 120. Here, in order to improve the uniformity of the entire LCD panel 150, the most light is refracted downward from the micro lens 133 positioned at the upper end of the lens fixing part 131 and the lens fixing part at the upper end of the lens fixing part 131. 131 The less the light is refracted toward the lower portion toward the lower end.

As described above, the present invention can reduce the weight of the LCD by directly transmitting light to the LCD panel using a light lens structure compared to the light guide plate, and also increase the light efficiency because light is directly incident to the LCD panel. It can be effective.

Claims (12)

A mold frame, a diffuser plate disposed on an upper surface of the mold frame to diffuse incident light, an LCD panel disposed on an upper surface of the diffuser plate to display information, and a side surface of the mold frame to provide the light. And a microlens structure which is installed on a front surface of the lamp structure and diverges the LCD panel into a plurality of predetermined blocks to guide the light to the LCD panel so as to correspond to the predetermined blocks. Backlight structure. The lens assembly of claim 1, wherein the micro lens structure comprises a lens fixing part installed on a front surface of the lamp structure, and a plurality of micro lenses extending along a length direction of the lamp structure and standing on the front of the lens fixing part. The backlight structure of the liquid crystal display device characterized by the above-mentioned. 3. The backlight structure of claim 2, wherein the lens structure has the same number of microlenses as the number of dividing the LCD panel into predetermined blocks. 3. The backlight structure of claim 2, wherein the microlenses are formed so that the amount of light that passes through the microlenses and is directed toward the LCD panel is different depending on the position of the microlenses. 4. The backlight structure of the liquid crystal display device according to claim 4, wherein the length of the arc of the LCD panel side decreases toward the LCD panel in the shape of the microlenses. The backlight structure of claim 2, wherein the cross-sectional shape of the lens structure is square and about 2.3 mm thick. The backlight structure of claim 2, wherein the lens fixing part is made of polymer and the microlens is made of glass. The backlight structure of claim 1, wherein the lens structure is spaced apart from the lower surface of the diffusion plate by a predetermined distance. The backlight structure of a liquid crystal display device according to claim 8, wherein the predetermined interval is about 0.7 mm. The backlight structure of claim 1, further comprising a reflector formed on a lower surface of the mold frame to reflect light. The backlight structure of claim 10, wherein the reflector is formed by silver plating on a lower surface of the mold frame. The backlight structure of claim 10, wherein the reflector is a silver plated sheet.