KR100313213B1 - Optical incident device of backlight of a light guide plate - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light incidence device of a light guide plate backlight. In particular, the present invention relates to the light incidence device according to the length of the reflector or the distance between the reflector and the fluorescent lamp and the distance between the fluorescent lamp and the light guide plate. The purpose of the present invention is to fabricate a reflector capable of optimizing light reflection and to produce a light incidence of a light guide plate backlight having a high brightness.

The light guide plate backlight of the present invention is a light guide plate in which a lattice is formed by a screen printing method or a V-cutting method printed in halftone shape, a fluorescent lamp disposed on one side of the light guide plate, and light emitted from the fluorescent lamp. A first reflector disposed at upper and lower portions of the fluorescent lamp at a predetermined interval to reflect the light toward the light guide plate to form an upper and lower surface, and having a bent portion connecting one of the upper and lower surfaces to form one or more bends, and an upper portion of the light guide plate. And a diffuser film attached to the display surface and a second reflector attached to the lower reflective surface of the light guide plate.

Description

Optical incident device of backlight of a light guide plate}

The present invention relates to a light incident device of a light guide plate backlight.

Recently, the light guide plate backlight, which has been spotlighted as a liquid crystal display (LCD) back light source, is increasing as the demand for LCD increases. Currently, the application range is gradually expanded to laptops, desktop PCs, and liquid crystal TVs. The LCD market is growing more than 30% a year, and the light guide panel backlight industry is also growing.

Unlike plasma display panels (PDPs) and field emission displays (FEDs), the display by the LCD itself is a light-receiving element, so it can maintain a uniform brightness across the entire screen. Backlight is required. The light guide plate is an essential element included in all LCDs, and the light is introduced from the side of the acrylic plate, and the light passes through the acrylic plate and comes out of the front panel by the reflecting plate. Currently used backlights include electroluminescence (EL) backlights, LED backlights, and CCFL (Cold Cathode Fluorescent Lamp) backlights. Among them, CCFL backlight is preferred because of its low power consumption and very bright white light. It is thin and low power consumption. CCFL backlight has a direct type and side light type, and recently, research on the side light type is being actively conducted according to the demand for thinner and lighter display unit. In addition, since the side light type light guide plate provides flat illumination, it is used as a flat panel display in various fields as well as a laptop fish and a liquid crystal TV, and its range is gradually spreading.

1 is a cross-sectional view showing a light incidence portion of a light guide plate backlight for explaining the present invention, wherein the light incidence portion of the light guide plate backlight protects the light guide plate 13, the fluorescent lamp 15, and the fluorescent lamp 15. , A reflector 12 attached to the lamp case 14 to reflect the light incident from the fluorescent lamp 15, and a diffuser film 11 to display the reflected light.

2A and 2B are diagrams illustrating a direct type and side light type light guide plate for explaining the present invention.

The light guide plate backlight using the fluorescent lamp includes a direct type backlight in which the fluorescent lamp 23 is mounted on the light guide plate 22 and the diffusion film 21 is installed thereon as shown in 2a, and the fluorescent lamp (shown in FIG. 2b). 26 is attached to the side of the light guide plate 28 and there is a sight light type backlight having the reflective film 25 and the diffuser film 24 attached to the light reflection surface and the display portion, respectively. FIG. 2A illustrates a direct backlight. Since the fluorescent lamp 23 is attached under the diffusion film 21, the luminance is high but the overall thickness is thick and the luminance of the portion of the fluorescent lamp 23 is high to obtain a uniform luminance distribution. There are no drawbacks. On the other hand, as shown in FIG. 2B, the side light type backlight is thinner because the fluorescent lamp 26 is attached to the light guide plate 28, and the uniformity of the luminance can be increased. In order to obtain a uniform luminance distribution, the bottom of the light guide plate 28 is formed by a screen printing method or a V-cutting method printed on a half-dot, and in order to increase light efficiency, the reflective film 25 and The diffusion films 24 are attached to each other. The fluorescent lamp 26 uses a CCFL lamp that has a low power consumption, can be ultra-fine, and has a long life, and attaches a reflector to the surface of the lamp case 27 so that light from the light source can be efficiently incident on the light guide plate 28. In form.

The light incidence part using the light guide plate varies greatly in the luminance and luminance distribution characteristics according to the reflecting surface treatment state, and this is entirely dependent on the improvement of the LCD quality, and thus research and development is needed to increase the brightness of the light guide plate.

Conventional notebook PCs, liquid crystal TVs, etc. have been developed a lot in size, weight or thickness. However, notebook PCs and portable personal digital assistants using liquid crystal displays are inconvenient in size and weight to carry. In order to overcome this drawback, the light guide plate backlight, which has been spotlighted as a back light source of a liquid crystal display device, requires a light guide plate and a reflector having a condition that can achieve a higher brightness while achieving a thinner display unit according to the demand for thinner and lighter display units. Doing. Here, in order to obtain the maximum light output from the surface of the light guide plate, the light incident area is maximized so as to allow the light emitted from the fluorescent lamp to enter the incident surface of the light guide plate as much as possible, or the light reflection from the incident surface is optimized to enter the light guide plate. There is a demand for manufacturing a light guide plate that maximizes the amount of light.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to light incident portions of a light guide plate backlight, and particularly affects the surface luminance of the light guide plate according to the length of the reflector, the distance between the reflector and the fluorescent lamp, and the distance between the fluorescent lamp and the light guide plate. It is to manufacture the reflector that can identify the influence and optimize the light reflection and design the light guide plate of high brightness. Therefore, the present invention is to obtain a light incidence portion of the light guide plate backlight having the optimal conditions through the embodiment using the side light type backlight and manufacturing a planar light guide plate through the brightness characteristics of the light incident portion. An object of the present invention is to obtain a light guide plate backlight light incident part having a reflector having upper and lower curved surfaces and upper and lower inclined surfaces so as to optimize light reflection at an incident surface to obtain a maximum amount of light.

In one embodiment for achieving the object of the present invention, the light incidence portion of the light guide plate backlight is disposed on a light guide plate having a lattice formed by a screen printing method or a V-cutting method printed on a dot dot, and disposed on one side of the light guide plate Fluorescent lamp and the upper and lower portions of the fluorescent lamp are disposed at regular intervals so as to reflect the light emitted from the fluorescent lamp toward the light guide plate side to form a top and bottom surface, and the one or more bends connecting the top and bottom surfaces are formed And a first reflector, a diffuser film attached to the upper display surface of the light guide plate, and a second reflector attached to the lower reflective surface of the light guide plate.

1 is a cross-sectional view showing a light incident value of the light guide plate backlight for explaining the present invention.

2A is a view showing a direct light guide plate for explaining the present invention;

2B is a view showing a side light type light guide plate for explaining the present invention.

3 is a graph showing characteristics of time and luminance with respect to a stabilized state of a fluorescent lamp;

FIG. 4 is a graph showing surface luminance in light guide plates processed in respective concave and planar shapes having lattice formed therein; FIG.

5A and 5B are cross-sectional views showing reflecting mechanisms for explaining the luminance characteristic according to the distance between the reflector and the fluorescent lamp according to the present invention;

6 is a graph showing luminance characteristics according to a distance between a reflector and a fluorescent lamp according to the present invention;

Fig. 7 is a sectional view showing the structure of a reflector capable of efficiently reflecting light for explaining a preferred embodiment of the present invention.

8 is a diagram illustrating a point for measuring luminance of a light guide plate;

9 is a graph showing luminance characteristics of a result of modifying a size of a reflector reflecting light according to the measurement point of FIG. 8;

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

33, 36, 50: Light guide plate 32, 51: Lamp case

30, 39: first reflector 34, 38: second reflector

31, 40: fluorescent lamps 29, 35: diffusion film

The light incident value of the light guide plate backlight according to the present invention is a light guide plate in which a lattice is formed by a screen printing method or a V-cutting method printed on a halftone dot, a fluorescent lamp disposed on one side of the light guide plate, and a light exiting from the fluorescent lamp. And a first reflector for reflecting light toward the light guide plate, a diffusion film attached to an upper display surface of the light guide plate, and a second reflector attached to a lower reflective surface of the light guide plate. Here, the first reflector is disposed on the upper portion of the fluorescent lamp spaced apart by a predetermined interval, the upper inclined surface formed to be inclined downward toward the light guide plate, the lower portion of the fluorescent lamp is spaced apart at a predetermined interval, the lower portion formed to be inclined upward toward the light guide plate side Is disposed on the inclined surface and the rear surface of the fluorescent lamp at a predetermined interval, the upper curved surface is formed to be convex outwardly connected to the upper inclined surface, and the lower curved surface formed to be convex outwardly connected to the upper curved surface and the lower slope surface. .

Before measuring the brightness of each plate, first measure the time until the fluorescent lamp emits light stably.

Figure 3 is a graph showing the time and brightness characteristics until a stable state after the power supply to the fluorescent lamp. Referring to Figure 3 it can be seen that after the power is supplied up to about 1 minute is rapidly increased and up to 15 minutes gradually increases to maintain a constant value after about 15 minutes. Therefore, the values used afterwards are those measured after 15 minutes or more after the lamp is powered on.

First, let's look at the luminance characteristics according to the presence / absence of the reflector in the light guide plate in which the lattice is formed by the screen printing method or the V-cutting method printed on the dots. The influence of the brightness of the reflector on the light guide plate and the surface brightness along the length of the concave and planar light guide plates are described with reference to FIG. 4.

Two light guide plates formed by lattice screen printing or V-cutting were processed into concave and planar shapes, respectively, and the luminance values were measured on the surface of the light guide plate before and after attaching the reflector. First, the concave light guide plate and the planar light guide plate on which the lattice is formed are manufactured in the same size, and the surface of the light guide plate is divided into three parts to measure luminance. The lamp is 3Watt, the light guide plate is 125 * 48mm and the driving voltage is 10V. In the light guide plate having the grating formed, the luminance value of the concave light guide plate was higher than that of the planar light guide plate before attaching the reflector, but the measurement after attaching the reflector was higher.

This shows that light emitted from the opposite side of the light guide plate can form a space between the light incidence planes of the light guide plate so that it can be properly reflected by the fluorescent lamp through the first reflector and enter the light incident surface of the light guide plate, whereas the concave type is a fluorescent lamp. It can be seen that the margin at which the light emitted from the opposite side of the light guide plate is incident on the light incident surface of the light guide plate is disadvantageous compared with the plane of the light incident surface. Therefore, in order to maximize the amount of light incidence, it can be seen that it is effective to make the light incidence plane of the light guide plate flat rather than concave in close contact with the fluorescent lamp. Herein, an appropriate distance between the fluorescent lamp and the light guide plate to obtain the optimum luminance is 0.5 to 1 mm.

5A and 5B are manufactured to examine luminance characteristics according to the distance between the first reflector 30 and the fluorescent lamp 31 and the distance between the fluorescent lamp 31 and the light guide plate 33 according to an embodiment of the present invention. A cross section of a light incident portion of a light guide plate backlight is shown.

As shown in FIG. 4, the presence or absence of the first reflector 30, the position of the fluorescent lamp 31 and the first reflector 30, etc. in the light guide plate 33 affect the surface brightness of the light guide plate 33. First, the first reflector 30 is fabricated, the lamp case 32 is installed outside the fluorescent lamp 31, and the first reflector 30 is attached to the inner circumferential surface of the lamp case 32. After the measurement, measure the luminance value by gradually increasing the distance. After the light guide plate 33 having a thickness of 3 mm was polished in a plane shape of 162 * 37.2 mm, and the position of the first reflector 30 was brought into close contact with each other, and the position was changed while floating at 0.5 mm intervals from the fluorescent lamp 31, respectively. Measure the luminance. Measure until the distance between the fluorescent lamp 31 and the reflector 30 is 5 mm. Reference numeral 29 is a diffusion film and reference numeral 34 is a second reflector.

FIG. 6 is a graph illustrating luminance characteristics according to a distance between the first reflector 30 and the fluorescent lamp 31 measured using the models of FIGS. 5A and 5B. The fluorescent lamp 31 is connected to the first reflector 30. It can be seen that the luminance value is improved when the distance is greater than the closely contacted state. After the fluorescent lamp 31 and the first reflector 30 were brought into close contact with each other, the brightness was improved as the distance was increased, and the brightness was the highest between 0.5 mm and 1 mm, and the brightness was drastically lowered thereafter. This is because when a certain distance is provided between the fluorescent lamp 31 and the first reflector 30, the light emitted from the inside of the fluorescent lamp 31 is reflected and incident on the light guide plate 33. Also, the fluorescent lamp 31 is in close contact. Since the heat emitted from the first reflector 30 is transferred to the fluorescent lamp 31 may not be raised to the temperature required to emit the maximum amount of light. Therefore, when designing the lamp case 32, it can be said that it is desirable to manufacture using a material having a low thermal conductivity.

Here, when the light emitted from the fluorescent lamp is viewed, the fluorescent lamp and the light guide plate may be divided into light reflected by the first reflector opposite to the lamp and incident on the light guide plate. The incident light from the part in close contact with the fluorescent lamp is incident on the light guide plate with almost no loss of light, and is transmitted to the inside of the light guide plate, but the light reflected from the opposite side is incident to the structure of the lamp case having the first reflector or the fluorescent lamp. The amount of incident light varies depending on the distance of. Accordingly, if the structure of the lamp case having the first reflector is designed in such a manner as to efficiently reflect light, the amount of light incident on the light guide plate may be increased, thereby increasing the surface luminance.

FIG. 7 shows the structure of the first reflector 39 which is designed to optimize the light reflection on the opposite side of the fluorescent lamp 40. In this structure, the light from the opposite side is reflected by the first reflector 39 twice. The light guide plate 36 is incident on the light guide plate 36. In addition, the size of the LCD module is minimized in consideration of the rise of the LCD module on the light guide plate 36. Reference numeral 35 is a diffusion film mounted on the upper display surface of the light guide plate 36 and reference numeral 38 is a second reflector mounted on the lower reflective surface of the light guide plate 36.

8 shows each measuring point A, B, C of the light guide plate 50. As a result of the measurement, the brightness improvement of about 8% was obtained. The luminance uniformity showed similar characteristics to the existing products, and it can be seen that the designed first reflector structure efficiently reflects the light from the fluorescent lamp and enters the light guide plate 50.

FIG. 9 is a graph showing luminance characteristics of a result of changing a size of a first reflector that reflects light. When the size of the first reflector is made in a design shape, the size of the first reflector is 10.4 mm, showing the highest luminance value. For the size above or below, the light reflection angle is different so that the luminance is gradually lowered.

It is preferable that the structure of the light guide plate backlight according to the present invention be planar rather than concave in the light incident part of the light guide plate in order to optimize the light incident amount. And it can be said that the influence on the surface brightness of a backlight according to the length of a 1st reflector is large. In addition, a suitable space is required between the fluorescent lamp and the light incident part of the light guide plate. When the shape of the first reflector is designed to have an optimal light incident amount, the first reflector may have a brightness improvement effect of about 8% when compared with a conventional product.

Therefore, if the design and fabrication of the first reflector, the distance between the first reflector and the fluorescent lamp, and the distance between the fluorescent lamp and the light guide plate are designed and manufactured, the light incidence device of the light guide plate backlight having improved luminance can be realized. .

Claims (8)

delete delete delete A grid is formed by a screen printing method or a V-cutting method printed on dot dots, and a light guide plate having a light incident surface on one side, A fluorescent lamp disposed along a light incident surface on one side of the light guide plate; An upper inclined surface spaced at a predetermined interval on an upper portion of the fluorescent lamp and inclined downward toward the light guide plate so as to reflect light emitted from the fluorescent lamp to the light guide plate side, and spaced apart at a predetermined interval on a lower portion of the fluorescent lamp; A lower inclined surface formed to be inclined upwardly to the side, an upper curved surface formed convexly extending outwardly from the upper inclined surface toward the rear surface of the fluorescent lamp, and a lower curved surface extending convexly outwardly from the lower inclined surface toward the rear surface of the fluorescent lamp; A first reflector having a bent portion that connects an upper curved surface and a lower curved surface to form at least one curvature on a rear surface of the fluorescent lamp; A diffusion film attached to an upper display surface of the light guide plate; A second reflector attached to a lower reflecting surface of the light guide plate; The light guide plate is formed such that the light incidence surface is formed in a plane so that the light incidence surface is perpendicular to the incident light reflected from the rear surface of the fluorescent lamp. The fluorescent lamp is spaced 0.5 to 1.0mm from the light incident surface of the light guide plate, and disposed 0.5 to 1.0mm from the first reflector, The first reflector is a light guide plate backlight light incident device, characterized in that the reflective film coated with a high reflector, the length of 10 to 11mm. delete delete delete delete