KR20060100791A - Ps lgp - piece shape light guide panel - Google Patents

Abstract

The present invention relates to a light guide plate structure of a large BLU using an LED as a light source, and has a structure in which a light guide plate in the form of a piece (PIECE) is combined to improve brightness and uniformity of the large BLU.

In the case of a large BLU using an LED as a light source, the light source is disposed on the side of the single plate LGP, or arranged on the bottom surface of the LGP so that light loss due to inefficient light transmission by an excessively long light path from the light source can be achieved. And fresnel surface reflection loss to improve the light utilization efficiency of the light source.

The present invention can reduce the cost and improve the product quality by using a small number of LEDs according to the light utilization efficiency.

The basic structure is the combination of each LED light source and PIECE-type light guide plate (PS LGP-PIECE SHAPE LIGHT GUIDE PANEL) that satisfies the optical internal reflection condition to minimize light loss. This structure divides the viewing area into several.

This type of light incident part increases the light incidence efficiency from the LED to the PS LGP, and the effective light output structure of the incident light to the upper surface of the BLU through the PS LGP divides the viewing area of the large BLU into cell units to improve the light transmission efficiency from each LED. By increasing the light utilization efficiency, the quantity of LED light sources used can be reduced to a minimum, and a relatively high brightness and uniformity can be achieved.

Light guide plate, total internal reflection, luminance improvement, fresnel reflection loss

Description

Light guide plate structure of large BLU (Back Light Unit) using LED as light source and light guide plate of PIECE type applied to it {PS LGP-PIECE SHAPE LIGHT GUIDE PANEL}

Figure 1a is a view showing a conventional general light guide plate in which the LED is arranged on the lower surface of the one-piece LGP.

Figure 1b is a view showing a conventional general light guide plate in which the LED is arranged on the side of a single plate LGP.

2A is a perspective view of an APS light guide plate (coupled product) according to an embodiment of the present invention.

Figure 2B is a side view of Figure 2A.

Figure 3a is a perspective view of a PS light guide plate (single) according to an embodiment of the present invention.

3B is a cross sectional view of FIG. 3A;

Figure 3c is a perspective view of the coupling portion with the LED light source of the PS light guide plate according to the embodiment of the present invention.

Figure 4a is a perspective view of a single PS light guide plate (when using two or more LED light source) according to another embodiment of the present invention.

Figure 4b is a perspective view of the PS light guide plate separately (when using two or more LED light source) according to another embodiment of the present invention.

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

100 APS light guide plate 110 PS light guide plate 111

112: lower surface of the light guide plate 113: light source coupling portion 115: LED

The present invention relates to a light guide plate structure of a large BLU using LED as a light source, and is particularly a structure in which the viewing area of the large BLU is divided into cell units and combined using a light guide plate in the form of a slice. The PS LGP is used to improve the efficiency of the light emitted from each LED, and to reduce the cost and quality of the BLU by using the minimum LED.

Liquid crystal displays (LCDs) are the mainstream of thin display devices in display products.

LCDs are used in a variety of devices ranging from televisions, notebook computers, desktop computer monitors, and mobile phones. Since liquid crystals of such liquid crystal display devices do not emit light by themselves, a liquid crystal panel must be used to display information on the liquid crystal panel. An auxiliary device for illumination is required, and when the surface light emitting device is coupled to the back of the liquid crystal, such a surface light emitting device is called a back light.

Such a backlight should be irradiated to the liquid crystal panel by forming a uniform surface light source, and is a very important component in terms of quality among the components constituting the LCD.

Typical backlights include light sources, light guide plates, diffusion sheets, prisms, and protective sheets. As a light source, a fluorescent lamp such as a mercury cold cathode fluorescent lamp (CCFL) or an LED is used. The light guide plate serves to guide the light from the light source evenly upward. The diffusion sheet serves to equalize the brightness by scattering light, and the prism refracts the light to condense it into the effective field angle to improve the brightness. The lower surface of the light guide plate is provided with a reflection sheet for reflecting the light emitted downward from the light guide plate to improve the light efficiency, each member is accommodated in the frame is coupled to the LCD substrate.

In order to cope with environmental regulations of various countries related to electronic components and to improve color reproducibility of display products, LEDs, which are mainly used for small liquid crystal displays as light sources of LCDs, are also used for large liquid crystal displays. However, because of the characteristics of the LED light source, when used in such a large BLU, the characteristics of the point light source is relatively stronger, so when the LED is arranged on the side of the single-plate LGP, the light loss due to the long light transmission path increases. Even when the LED is arranged on the lower surface of the single plate LGP, fresnel reflection loss increases and the light absorption loss of each component also increases due to the structure for effectively diffusing the point light source. Due to this problem, a large BLU must use a relatively larger number of LEDs than the number of LEDs applied to a small BLU. This increases power consumption, causes inefficiency of the light source, makes it difficult to obtain high quality products related to luminance and uniformity, which are important quality factors for BLU products, and leads to cost increase.

FIG. 1A illustrates a light guide plate used in a general large-scale backlight as described above, in which a LED used as a light source is arranged on a bottom surface of a light guide plate having a single plate, and FIG. 1B illustrates a single plate of an LED used as a light source. It is a structure arranged on the side of the light guide plate.

The present invention has been made in view of the above, and when manufacturing a large BLU using the LED as a light source, the light emitted from each LED having the point light source characteristics is efficiently emitted to the upper surface of the BLU to increase the light utilization efficiency, The purpose is to improve the brightness and uniformity, and to reduce the LED usage quantity to the minimum.

The light guide plate according to the present invention for achieving the above object, in the light guide plate applied to the backlight unit of a large liquid crystal display device, a structure in which the light guide plate of the slice (PIECE) form by dividing the viewing area of the BLU by cell units, The light incidence portion of each light guide plate in the form of each piece (PIECE) is characterized in that the shape (Fig. 3a) satisfying the optical internal total reflection conditions. When combining the respective PS light guide plate is as shown in Figure 2a. The lower surface of each PS light guide plate is inclined at a constant inclination angle (FIG. 3B), and this inclination angle is determined in relation to the incident shoulder height difference of the light incident part and the thickness t of the tip of the light guide plate including the reflective sheet having the same dimensions. This is not for optical effects, but for mechanical design purposes.

Hereinafter, with reference to the accompanying drawings the present invention will be described in more detail. 2A and 2B illustrate an embodiment of an APS LGP (Assembled Piece Shape LGP) according to the present invention, and each PS (Piece shape) LGP is a shape of an APS (Assembled Piece Shape) LGP. . 3A and 3B illustrate an embodiment of a PS light guide plate according to the present invention. The light incident part 111 has a shape satisfying the optical total internal reflection condition, so that the loss is minimized until the light incident from the light source 115 enters the viewing area of the light guide plate. As shown in FIG. 3C, the light source coupling part 113, which is a portion coupled to the LED light source, has a concave hemispherical shape, thereby minimizing surface reflection loss when light emitted from the LED is incident on the PS light guide plate. The PS light guide plate 112 has an arbitrary reflection or diffusion pattern to allow incident light to exit to the top surface, and the stepped portion of the light incident portion of the LGP can be supported so that each PS light guide plate is coupled to each other. h), and this step is equal to the thickness (t) of the end of the LGP including the reflective sheet so that the upper surface of the combined light guide plate (APS LGP) maintains a flat shape, thereby forming a dimensionally identical surface. 4A illustrates the shape of the light incidence portion of the PS light guide plate when two or more LED light sources are used. 4A illustrates an example in which two LEDs are used for convenience, but the shape of the light incident part 111 for inducing light shown in FIG. 3A may be added according to the number of LEDs used for each PS LGP. If the number is large, the shape of the light incidence part as shown in Fig. 4B may be adopted. As described above, the structure shown in FIGS. 4A and 4B can easily change the luminance according to the cross-sectional area of the PS light guide plate.

In this way, when the light guide plate having the structure of combining the light guide plate 110 having the light incidence part 111 satisfying the optical internal reflection condition is applied to a large backlight unit, the loss of light emitted from the light source is minimized to effectively the upper surface of the BLU. Since it can emit light, the brightness and uniformity of the BLU can be improved and the number of LED light sources used can be reduced compared to the conventional method of arranging the LEDs on the side of the LGP or on the lower surface of the LGP.

The invention is not limited to the embodiments described above, and various changes and modifications can be made by those skilled in the art to which the invention pertains, which is defined in the appended claims. It is included in the spirit and scope.

As described above, the present invention is a light guide plate structure of a large BLU using the LED as a light source by taking a structure that combines using a light guide plate of the shape (Piece) having the shape of the light incident portion of the optical internal reflection conditions. The conventional light guide plate of three plates can be used to improve the light loss problem when the LEDs are arranged on the side or the bottom.

Claims (6)

A light guide plate structure of a large BLU (backlight unit) using an LED as a light source, wherein the light guide plate of a piece shape is combined. The shape of the PS light guide plate according to claim 1, according to the LED light source. The shape of the light incidence portion of the PS light guide plate according to claim 2. The PS light guide plate has a structure in which a light incident part through which light is incident from a light source satisfies optical internal reflection conditions to increase light incident rate. The shape according to claim 2, wherein there is a step in the shoulder portion of the PS light guide plate. The shoulder portion of the PS light guide plate has a thickness equal to the thickness of the end portion of the light guide plate including the reflective sheet so that the top surface of the Assembled Piece Shape (APS) light guide plate combined with the PS light guide plate is flat. The method of claim 3, wherein the coupling portion of the LED light source and the PS light guide plate hemispherical shape The shape of the PS light guide plate according to claim 3, according to the number of LED light sources.

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