KR19990045967A - 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, and in particular, according to the structure of a lamp case having a reflector or the length of the reflector or the distance between the reflector and the fluorescent lamp and the fluorescent lamp and the light guide plate. The purpose of the present invention is to fabricate a reflector capable of optimizing light reflection by grasping the influence on the surface brightness of a light source, and designing a lamp case attached to the inside of the light guide plate having a high brightness.

The light guide plate backlight optical device 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 in halftone shape, a fluorescent lamp disposed on one side of the light guide plate, a lamp case, and the fluorescent lamp Upper and lower surfaces disposed at regular intervals on the upper and lower portions of the fluorescent lamp so as to reflect the light from the lamp toward the light guide plate, a vertical plane disposed on the rear surface of the fluorescent lamp at regular intervals and vertically formed in the vertical direction; And a first reflector formed of a curved surface connecting surfaces to each other with a predetermined curvature, 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. do.

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 so that 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 terms of size and weight for portable users. In order to overcome these drawbacks, the light guide plate backlight, which has been spotlighted as a rear 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 The present invention relates to light incident portions of a light guide plate backlight, in particular the structure of a lamp case having a reflector or the length of a reflector attached to the inner circumferential surface of the lamp case, and the distance between the reflector and the fluorescent lamp. And a reflector capable of optimizing light reflection by grasping the influence on the surface brightness of the light guide plate according to the distance between the fluorescent lamp and the light guide plate, and designing a lamp case based on this to design a high brightness light guide plate. 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.

The present invention is to produce a lamp case that can be produced in large quantities and at the same time optimal light reflection by supporting the shape of the first reflector in the case of using the reflective film as the first reflector.

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 lamps, a lamp case, the upper and lower surfaces arranged at regular intervals on the upper and lower portions of the fluorescent lamp to reflect the light emitted from the fluorescent lamp toward the light guide plate side, and are arranged at regular intervals on the back of the fluorescent lamp A first reflector formed of a vertical plane vertically formed in a direction, a curved surface connecting the upper and lower surfaces with a predetermined curvature, a diffusion film attached to an upper display surface of the light guide plate, and a lower reflective surface of the light guide plate. And a second reflector.

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;

7A and 7B are cross-sectional views showing a light guide plate backlight light incident portion constructed in accordance with the present invention;

FIG. 8 is a cross-sectional view illustrating a light guide plate backlight light incident part according to an exemplary embodiment of the present invention having a plastic lamp case in the structure of FIG. 7A.

9 is a view showing a point for measuring the brightness of the light guide plate;

FIG. 10 is a graph illustrating luminance characteristics of a result of modifying a size of a reflector reflecting light according to the measurement point of FIG. 9; FIG.

11 is a view showing the position of the screw hole for fixing the lamp case

12 is a graph showing the luminance characteristics according to the size of the screw holes in the light guide plate

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

33, 48, 50: Light guide plate 32, 49, 51: Lamp case

30, 47: First reflector 34, 43: Second reflector

31, 45, 55: fluorescent lamps 29, 44: diffusion film

46: distance between the lamp case and the first reflector

The light ridge 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 in halftone shape, a fluorescent lamp disposed on one side of the light guide plate, a lamp case, and the Upper and lower surfaces disposed at regular intervals at upper and lower portions of the fluorescent lamp to reflect light from the fluorescent lamp toward the light guide plate, vertical planes disposed at regular intervals on a rear surface of the fluorescent lamp and vertically formed in the vertical direction; And a first reflector formed of a curved surface connecting upper and lower surfaces to each other with a predetermined curvature, 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. .

In addition, when the thickness of the fluorescent lamp is the same as or thicker than the thickness of the light guide plate, the shape of 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, and A lower inclined surface spaced apart from the lower portion of the fluorescent lamp and formed to be inclined upward toward the light guide plate, a vertical plane spaced at a predetermined distance from the rear surface of the fluorescent lamp and vertically formed in the vertical direction, and the upper and lower sloped surfaces And the vertical plane is formed as a curved surface connecting each other with a predetermined curvature. However, when the thickness of the fluorescent lamp is thinner than the light guide plate, the shape of the first reflector is a curved surface that is spaced apart at regular intervals on the upper and lower portions of the fluorescent lamp to connect the upper and lower surfaces with a predetermined curvature. Is formed.

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 into a concave shape rather than a structure 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 illustrate a light guide plate backlight fabricated to investigate 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 the present invention. The cross section of the light incidence part 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.

7A and 7B are cross-sectional views illustrating a light guide plate backlight light incident part configured to explain the present invention, and FIG. 8 is a light guide plate backlight light according to an embodiment of the present invention having a plastic lamp case in the structures of FIGS. 7A and 7B. It is sectional drawing which shows an incidence part.

7A, 7B and 8 give up a part of the light emitted from the opposite side of the fluorescent lamp 45 by modifying the structure of the lamp case 49, but it is easy to manufacture when using the reflective films as the first reflector 47. Because of this mass production structure. The diffuser film 44 mounted on the upper display surface of the light guide plate 48, the second reflector 43 mounted on the lower reflecting surface, the fluorescent lamp, and the first reflector 47 are used as the basic configuration. As shown in FIGS. 9A and 9B, the shape of the first reflector 47 is formed, the first reflector 47 is attached to the light guide plate 48, and the shape of the first reflector 47 is fixed with the lamp case 49. . Here, the interval 46 between the lamp case 49 and the first reflector 47 is to insulate the fluorescent lamp so that it can rise to the temperature necessary to emit the maximum amount of light. In order to maximize the amount of light incidence, the luminance value of the light guide plate 48 to which the first reflector 47 was manufactured was measured by comparing uniformity and luminance characteristics of the existing product with reference to FIGS. 7A and 7B. First, the fluorescent lamp 45 was waited for a stable state to measure the luminance of the existing product, and then the light guide plate was divided into three parts to measure uniformity and luminance. Then, after assembling the lamp case of the existing product and waited until the fluorescent lamp 45 is stable, the luminance value was measured in the same manner. In addition, FIG. 7A shows that when the thickness of the fluorescent lamp 45 is equal to or thicker than the thickness of the light guide plate 48, the shape of the first reflector 47 is spaced a predetermined distance from the upper portion of the fluorescent lamp 45. The upper inclined surface disposed to be inclined downward toward the light guide plate 48, the lower inclined surface spaced at a predetermined interval below the fluorescent lamp 45, and the inclined upwardly toward the light guide plate 48, and the fluorescent lamp ( 45) spaced apart at regular intervals, the vertical plane formed vertically in the vertical direction, and the upper inclined surface and the lower inclined surface and the vertical plane is formed as a curved surface connecting each other with a predetermined curvature. 7B illustrates that when the thickness of the fluorescent lamp 45 is thinner than that of the light guide plate 48, the shape of the first reflector 47 is disposed to be spaced apart from each other by a predetermined interval on the upper and lower surfaces of the fluorescent lamp 45. It is shown that it is formed by the curved surface which connects upper and lower surfaces by predetermined curvature.

FIG. 9 illustrates measurement points A, B, and C of the light guide plate 50 connected to the lamp case 51 manufactured as in FIG. 8. As a result of the measurement, the brightness improvement of about 8% was obtained when compared with the existing product. 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. 10 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.

FIG. 11 is a view for explaining the position of the screw hole 58 for fixing the lamp case to the light guide plate 57 after configuring the fluorescent lamp 55 and the first reflector 56 as described above. 57 and a hole 58 in the lamp case to fix the light guide plate 57 and the lamp case.

FIG. 12 is a graph showing luminance characteristics according to the size of a screw hole in the light guide plate. After processing the screw holes in the existing light guide plate by size, the luminance value according to the size of the hole is measured to provide an optimal light guide plate design. In the present invention, after processing the light guide plate to 29 * 108mm, the side surface was polished to minimize the diffuse reflection of the light guide plate and then measured the basic value. Then, after processing a hole with a diameter of 1mm in the same position as the screw hole of the light guide plate in the existing product, the luminance value was measured while gradually increasing the size of the hole. First, the luminance value when the hole was not processed in the light guide plate was measured, and gradually, the size of the hole was increased by 1 mm. Referring to FIG. 11, there was a difference in luminance value according to the size of the hole, and there was no significant difference between the diameters of the hole between 1 mm and 2 mm as before the hole was processed, but the luminance value rapidly decreased for sizes larger than 2 mm. Thus, when manufacturing the light guide plate, considering the size of the hole of the light guide plate, it can be seen that the light guide plate having an optimal luminance value can be designed.

It is preferable that the structure of the lamp case having the first reflector of the light guide plate backlight according to the present invention be flat rather than concave to form the light incident portion of the light guide plate in order to optimize the amount of light incident. In addition, it can be said that the influence on the surface brightness of the backlight is large according to the structure or shape of the lamp case having the first reflector and the length of the first reflector attached to the inner surface of the lamp case. When attaching the first reflector to the lamp case, an appropriate space between the fluorescent lamp and the first reflector can improve the surface brightness of the light guide plate. 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. It can be seen that not only the first reflector but also the screw hole of the light guide plate affects the overall brightness of the light guide plate.

Therefore, the design and manufacture of the lamp case having the first reflector, the shape 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 have better luminance. The light incidence device of the light guide plate backlight may be implemented.

Claims (10)

A light guide plate having a lattice 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; Lamp case, Upper and lower surfaces disposed at regular intervals on the upper and lower portions of the fluorescent lamp to reflect the light emitted from the fluorescent lamp toward the light guide plate, and vertical planes disposed at regular intervals on a rear surface of the fluorescent lamp and vertically formed in the vertical direction; A first reflector formed of a curved surface connecting the upper and lower surfaces with a predetermined curvature, 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. The upper sloped surface of claim 1, wherein when the thickness of the fluorescent lamp is equal to or thicker than the thickness of the light guide plate, the shape of the first reflector is spaced at a predetermined distance from an upper portion of the fluorescent lamp and is inclined downward toward the light guide plate. And a lower inclined surface spaced apart from the lower portion of the fluorescent lamp by a predetermined interval and vertically spaced apart from the rear surface of the fluorescent lamp by a predetermined space in the vertical direction, and a vertical plane vertically formed in the vertical direction and the upper sloped surface. And a curved surface connecting the lower inclined plane and the vertical plane to each other with a predetermined curvature. The method of claim 1, wherein when the thickness of the fluorescent lamp is thinner than the light guide plate, the shape of the first reflector is spaced apart from each other by a predetermined interval to connect the upper and lower surfaces and the upper and lower surfaces with a predetermined curvature. Light incident device of the light guide plate backlight, characterized in that formed in the curved surface. The light guide plate backlight light incident according to any one of claims 1 to 3, wherein one side incident surface of the light guide plate is formed in a plane so that the incident surface is vertical and the distance from the fluorescent lamp is 0.5 to 1.0 mm. Device. The light guide plate backlight light incident device of claim 4, wherein a length of the first reflector, which is partially attached to an inner circumferential surface of the lamp case, is 10 to 11 mm. 6. The light guide plate backlight light incident device of claim 5, wherein a distance between the fluorescent lamp and the first reflector is 0.5 to 1.0 mm. The light guide plate backlight light incident device of claim 6, wherein the first reflector uses a reflective film coated with a high reflector. The light guide of claim 7, wherein the lamp case is provided in a lattice form to fix the portion of the first reflector positioned on the rear surface of the fluorescent lamp to prevent sagging of the first reflector. Device. The light guide plate backlight light incident device of claim 8, wherein the grid-shaped lamp case forms a predetermined space with the first reflector. The light guide plate backlight light incident device of claim 9, wherein a screw hole is formed at one end of the light guide plate to fix the lamp case to the light guide plate, and the diameter of the screw hole is 1 to 2 mm.