KR20030000467A - Flat type backlight for LCD using optical fiber - Google Patents

Abstract

PURPOSE: A backlight using optical fibers for a liquid crystal display device is provided to improve the luminance and uniformity in the luminance of the light radiated to an LCD panel from a fluorescent lamp of the backlight, thereby displaying the characters more clearly. CONSTITUTION: A backlight using optical fibers for a liquid crystal display device includes a diffusion plate(30) for uniformly diffusing radiated light, a fluorescent lamp(10) located below the diffusion plate for emitting light and having an upper plate formed in a predetermined sectional shape for the light emission, doped with a fluorescent material inside, and forming single-channel cells, a lower surface integrated with the upper plate with a predetermined width, and electrodes attached to both ends of the upper plate, optical fiber bundles(40) positioned between the single-channel cells and formed with scratches for radiating the light toward the diffusion plate, and a reflection plate(20) located below the fluorescent lamp for reflecting the light emitted from the fluorescent lamp.

Description

Flat type backlight for LCD using optical fiber}

The present invention relates to a backlight for an LCD using an optical fiber, and more specifically, to improve the brightness and luminance uniformity of the light irradiated to the LCD panel from the fluorescent lamp of the backlight by using the optical transmission characteristics of the optical fiber, thereby increasing the character readability of the LCD panel. The present invention relates to a backlight for an LCD using an optical fiber with which a large area can be easily increased.

A liquid crystal display device (hereinafter referred to as "LCD") used as a display device for text, graphics, video, etc., causes less eye fatigue than conventional CRT display devices, and can be miniaturized, light weighted, and low power. It is very popular as a next generation display device of television, and commercialization is progressing gradually.

Referring to the structure of the LCD panel for displaying a character or an image in a conventional LCD is as follows. First, a liquid crystal material is injected between a pair of surface-treated transparent glass plates, and an electrical signal (voltage) is supplied using an LCD controller that generates a driving signal to the injected liquid crystal material, thereby causing a phase change of the liquid crystal material. . The LCD driving circuit can display specific characters or images by giving different voltage values according to the distribution of liquid crystal materials.

However, in LCD, since the panel on which the characters are displayed does not emit light by itself, a means of assisting the visual recognition of the contents (characters or logos) displayed on the panels is required. Background Art [0002] A back light system using a lamp that irradiates light from the side or the back of a liquid crystal panel is widely used as an auxiliary means.

Conventionally used backlight systems are classified into an edge type backlight and a direct type backlight according to the position of a fluorescent lamp for projecting light. An edge type backlight is a method in which light sources are positioned below both sides of a panel so that light incident from the light source generates a surface light source by a light guide plate and a reflecting plate to illuminate cells of the LCD panel. This edge method indirectly induces light emitted from the light source, which has the advantage of high luminance uniformity, but on the other hand, there is a problem that the luminance is relatively low.

In addition, the direct backlight has a light source positioned directly under the LCD panel, and a diffuser plate is disposed on the front surface of the light source, and a reflector plate is disposed on the rear surface to reflect and diffuse light emitted from the light source, thereby dimming the shell of the LCD panel. to be. Since the direct method uses light efficiently by using a reflecting plate and a diffusion plate, high brightness can be obtained, and therefore, it is suitable for backlights requiring high brightness. However, there was a limit in providing sufficient brightness depending on the size of LCD panel which is gradually becoming larger. In addition, there was a problem of low luminance uniformity.

In order to solve this problem, a flat panel backlight structure has been filed by the present applicant. Although the flat panel backlight structure can be irradiated with light over a large area, the luminance and luminance uniformity are much improved compared to the conventional direct type or edge type backlight, but the present inventors have further improved the structure of the flat panel backlight. It was early.

The present invention has been made to solve the above problems, an object of the present invention is to improve the luminance and luminance uniformity of the light irradiated to the LCD panel and the large area because the luminance and luminance uniformity is the same regardless of the size of the LCD panel It is to provide a backlight structure for an LCD using an easy optical fiber.

Another object of the present invention is to provide an LCD backlight using an optical fiber that has improved the luminance and luminance uniformity of the flat panel backlight for LCDs filed by the present applicant.

According to an aspect of the present invention, there is provided an LCD backlight for irradiating light for decrypting characters generated on an LCD panel, comprising: a diffusion plate for uniformly diffusing the irradiated light; Located in the lower part of the diffusion plate and emits light, it is formed integrally on the bottom surface of the lower surface and the bottom surface having a constant width, the cross section has a specific shape for the emission of light, the phosphor is coated inside the single channel cell A flat fluorescent lamp comprising an upper plate constituting an electrode and an electrode attached to both ends of the upper plate; An optical fiber bundle positioned between the single channel cells and having a scratch for irradiating light in the direction of the diffusion plate; Located at the bottom of the flat fluorescent lamp is characterized in that consisting of a reflecting plate for reflecting the light emitted from the flat fluorescent lamp.

According to another feature of the invention, the cell cross section of the top plate may have a shape of semi-circular, oval, square, rhombus, etc., and also the reflecting plate may have a shape such as flat, rhombus, semi-circular, dish-like.

1 is an embodiment of the installation structure of the fluorescent lamp and the optical fiber according to the present invention,

Figure 2 is another embodiment of the installation structure of the fluorescent lamp and the optical fiber according to the present invention,

3 is an embodiment of a backlight structure according to the present invention;

4 is another embodiment of a backlight structure according to the present invention;

5 is a perspective view showing an optical fiber structure,

6 is a configuration diagram of an optical fiber and an LED according to the present invention;

7 is a graph showing the light transmission loss of the optical fiber.

※ Explanation of symbols about main part of drawing ※

10: fluorescent lamp 20: reflector

30: diffuser 40: optical fiber

40a: scratch 40b: twisted layer

50: LED 100: bottom view

102: top plate 104: channel cell

106: coupling part

Referring to the present invention having such characteristics in detail as follows.

The present invention is to improve the readability by increasing the brightness and luminance uniformity of the light irradiated to the LCD panel using the optical fiber bundle, especially as a flat panel backlight.

1 is a preferred embodiment of the backlight according to the present invention, a flat type fluorescent lamp 10 used as a light source in the backlight and the optical fiber 40 bundle by a plurality of optical fiber strings located adjacent to the fluorescent lamp 10 The installation state of the is shown.

The optical fiber 40 bundle is used as an auxiliary light source for providing additional light to the light emitted from the fluorescent lamp 10, that is, the fluorescent lamp 10, as a separate light source for the optical fiber 40 It is possible to use the LED 50 or to induce the light of the fluorescent lamp 10 itself to be configured as a light source. In the former case, there are disadvantages in that the structure is complicated and the cost is added.

The bundle of optical fibers 40 is installed with a constant height between each single channel cell 104 of the fluorescent lamp 10. The height is preferably maintained at the same height as the upper end of the channel cell 104.

One optical fiber 40 is installed between each channel cell 104. In order to reduce the use of the LED 50 may be configured to connect the ends of the optical fiber 40 into one, and to irradiate light emitted from the LED 50 to the connected coupling portion. The light emitting structure by the optical fiber will be described later with reference to FIG.

Figure 2 is another preferred embodiment of the backlight according to the present invention, the difference from Figure 1 can be seen that the up and down state of the fluorescent lamp 10 is reversed. This uses the characteristics of the fluorescent lamp 10 of the present invention, since the fluorescent lamp 10 can irradiate light in both up and down directions, the installation direction can be changed according to the LCD in which the fluorescent lamp 10 is used. Except for the upside down direction is the same as that of Figure 1, detailed description thereof will be omitted. In this case, however, it is apparent that the scratches formed on the surface of the optical fiber 40 to emit light passing through the optical fiber 40 should be directed toward the LCD panel.

FIG. 3 is a side view of the backlight using the fluorescent lamp 10 and the optical fiber 40, and is configured based on the fluorescent lamp 10 of FIG. As shown, the diffusion plate 30 for uniformly spreading the light irradiated from the top to the bottom; Located in the lower part of the diffusion plate 30 and emits light, the cross section has a specific shape for light emission (semi-circular, elliptical, square, rhombus, etc.) and a phosphor is coated therein, and a single channel cell 104 is provided. A flat plate type fluorescent lamp 10 including an upper plate 102 constituting the upper plate 102, a lower surface 100 integrally formed with the upper plate 102, and electrodes attached to both ends of the upper plate 102. )Wow; An optical fiber bundle 40 positioned between the single channel cell 104 and having a scratch for irradiating light in the direction of the diffusion plate 30; And it can be seen that it is composed of a reflecting plate 20 positioned below the flat fluorescent lamp 10 to reflect the light emitted from the flat fluorescent lamp 10.

The diffusion plate 30 serves to diffuse light and to increase luminance uniformity of the backlight. As the material of the diffusion plate 30, PET, polycarbonate, or the like is usually used, and a plurality of PET and polycarbonate sheets on which a diffusion material is applied are laminated on the surface. The diffusion plate 30 used in the present invention can be configured using a diffusion plate commonly used. Of course, if the light scattering characteristics of the diffusion plate is excellent, it is obvious that higher luminance uniformity can be obtained.

The flat fluorescent lamp 10 is a light source of a backlight and has a high luminance and a high luminance uniformity compared to a conventional CCFL (cold cathode fluorescent lamp) due to its structural characteristics. In addition, since the conventional CCFL takes a long time to install, the flat fluorescent lamp 10 used in the present invention is integrally formed in a form in communication with the top plate 102 where the channel cells 104 are formed. There is a side benefit of shortening the time required for installation. Although not shown in detail, the channel cells 104 have channel cells and end portions adjacent to each other and communicate with each other, and have a serpentine shape.

According to the backlight of the present invention, two or three CCFLs are required to sufficiently illuminate a conventional LCD panel having a size of 15.1 ", and by installing only one flat fluorescent lamp 10 and a bundle of optical fibers 40, High luminance and uniformity of luminance can be obtained, especially since the electrode connector terminals for connecting each of them are required to connect the electrodes of the CCFL, the flat fluorescent lamp 10 requires only one pair of electrode connector terminals. Has the advantage of being simplified.

Furthermore, since the flat fluorescent lamp 10 of the present invention has a surface light source shape, the thickness of the flat fluorescent lamp 10 can be reduced, thereby facilitating the compactness and weight of the system having the LCD. This can be evident in view of the flat panel fluorescent lamp 10 used in the present invention in view of the trend that the size of the LCD panel gradually increases in size.

The bundle of optical fibers 40 adjacent to the fluorescent lamp 10 is located between the upper ends of the channel cells 104, as shown. As is well known, the optical fiber 40 is used to transmit light, and in the present invention, the optical fiber 40 is positioned between the channel cells 104 to direct the light in the direction of the LCD panel (the direction in which the diffusion plate 30 is located). It is used to increase readability by increasing luminance and uniformity by emitting radiation. Since the optical fiber does not emit light from the outer circumferential surface other than the actual end, scratches are formed for the light emission.

FIG. 5 shows a structure of a single strand of plastic optical fiber 40, which is conventionally used, and a thin clad made of a core made of high-purity acrylic resin (PMMA: Poly Methyl MethAcrylate) and a special fluoropolymer (F-PMMA: Fluorinated Poly Methyl Meth Acrylate). It consists of a clad layer. Since the refractive index of the clad is lower than that of the core, light from one end of the optical fiber can cause total reflection at the interface between the core and the clad, thereby transferring the core to the other fiber end. The structure of the plastic optical fiber is in the form of a step index profile. The refractive index of the core is 1.495, and the refractive index of the clad is 1.402.

7 is a graph showing the light transmission loss of the optical fiber, it can be seen that the reduction rate of light with distance. It can be seen that the optical fiber used in the backlight of the present invention as the loss curve for the plastic optical fiber and the glass optical fiber can be used without great loss because the distance is very short.

FIG. 6 is a view illustrating a coupling state of an optical fiber used in the present invention. In order to reduce the number of LEDs 50 used as a light source, optical fibers are connected three by three and light is connected through one optical fiber coupling unit 106 connected thereto. It is configured to investigate. Each optical fiber is located crossing each other between the channel cells 104. Of course it is also possible to connect all the optical fibers to the coupling portion 106. As described above, the bundle of optical fibers 40 located between the channel cells 104 of the upper plate 102 has an effect of improving brightness and uniformity of light by irradiating light on its own.

In addition, the surface of the optical fiber bundle 40 for the light emission to form a scratch (40a) or the clad is broken to form a twist layer (40b) to perform light radiation. The scratch 40a may be formed in a straight line, oblique line, or a network structure form, and may provide an optimal light emission condition by adjusting the light emission amount by adjusting the thickness and spacing of the line. Scratch 40a should be cut to a depth that can penetrate the cladding layer of the optical fiber, of course.

In addition, it is described in the drawing that the light is irradiated from the LED 50 through the coupling unit 106, it is also possible to use the light source by inducing light from the side of the upper plate (102). In other words, the light emitted from the side of the top plate 102 is extinguished without being irradiated to the LCD panel, but concentrates the light emitted from the side of the top plate 102 or penetrates the side of the top plate 102. By connecting so that the light source can be secured without using the LED 50.

On the other hand, the reflector 20 serves to concentrate the light emitted from the flat fluorescent lamp 10 to the cell of the LCD panel, the loss of light depends on the reflection efficiency of the reflector 20. PE or PET is used as the material and is used in the form of a film. The shape of the reflector plate 20 may be in various forms in order to increase the reflection efficiency, it is apparent that it can be configured in other modified forms such as rhombus, flat plate, dish type, semi-elliptic, etc., all of these modifications It will belong to the claims of the present invention.

FIG. 4 is a further embodiment of the backlight of the present invention constructed based on FIG. 2, comprising: a diffuser plate 30 for uniformly diffusing light irradiated from top to bottom; Located in the lower portion of the diffusion plate 30 and emits light, the lower surface 100 having a predetermined width, and integrally formed on the bottom surface of the lower surface 100 and has a specific shape for the emission of light A flat fluorescent lamp 20 including a top plate 102 having a phosphor coated therein and forming a single channel cell 104 and electrodes attached to both ends of the top plate 102; An optical fiber bundle 40 positioned between the single channel cell 104 and having a scratch for irradiating light in the direction of the diffusion plate 30; And it can be seen that it is composed of a reflecting plate 20 positioned below the flat fluorescent lamp 10 to reflect the light emitted from the flat fluorescent lamp 10. This structural feature is that the position of the fluorescent lamp 10 and the bundle of the optical fiber 40 is inverted and the effect is also similar, so the detailed description is omitted.

Even in the case shown in FIG. 4, the optical fiber bundles 40 have scratches 40a formed on the surface thereof, such that light passing through the inside of the optical fiber radiates to the outside, or a twisted layer of the optical fiber bundles. By fabricating in the form (40b), the same light emitting effect can be obtained.

In other words, when the two ends of the optical fiber are held and rotated in opposite directions, the fiber becomes twisted itself. At this time, the cladding layer of the optical fiber is broken and a gap is formed, and the light passing through the inside of the optical fiber passes through the cracked cladding layer. Light emission is made possible by configuring to radiate to the outside. Of course, since the formation of the twist layer 40b cannot be selectively performed as compared with the scratch 40a, there is a disadvantage in that light emission efficiency is lowered. However, this can be corrected to some extent by adjusting the twisted spacing of the optical fibers.

Although the scratch 40a and the twist layer 40b are shown in FIG. 6, it is clear that only the scratch or the twist layer can be selected and configured in an actual configuration.

According to the LCD flat panel backlight structure of the present invention, the luminance and luminance uniformity of the light irradiated to the LCD panel is improved, and the luminance and luminance uniformity are the same regardless of the size of the LCD panel, so that the large area is easy and the structure is easy. It is simple and can shorten working time and has the advantage of easy scalability.

Claims (6)

An LCD backlight for irradiating light for decrypting characters generated on an LCD panel, comprising: a diffusion plate (30) for uniformly diffusing the irradiated light; Located on the bottom of the diffusion plate 30 and emits light, the cross section has a specific shape for the emission of light, a fluorescent material is coated on the inside and forming a single channel cell 104 and the top plate 102 A flat fluorescent lamp 10 which is integrally formed with a) and includes a lower surface 100 having a predetermined width and electrodes attached to both ends of the upper plate 102; An optical fiber bundle 40 positioned between the single channel cells 104 and having a scratch 40a for irradiating light in the direction of the diffusion plate 30; And a reflecting plate (20) positioned below the flat fluorescent lamp (10) to reflect light emitted from the flat fluorescent lamp (10). An LCD backlight for irradiating light for decrypting characters generated on an LCD panel, comprising: a diffusion plate (30) for uniformly diffusing the irradiated light; Located in the lower portion of the diffusion plate 30 and emits light, the lower surface 100 having a predetermined width, and integrally formed on the bottom surface of the lower surface 100 and has a specific shape for the emission of light A flat fluorescent lamp 10 including a top plate 102 having a phosphor coated therein and forming a single channel cell 104, and electrodes attached to both ends of the top plate 102; An optical fiber bundle 40 positioned between the single channel cells 104 and having a scratch 40a for irradiating light in the direction of the diffusion plate 30; And a reflecting plate (20) positioned below the flat fluorescent lamp (10) to reflect light emitted from the flat fluorescent lamp (10). The method according to claim 1 or 2, Each optical fiber of the optical fiber 40 bundle is a backlight for an LCD using the optical fiber, characterized in that installed at the same height as the protruding end of the channel cell (104) of the top plate (102). The method according to claim 1 or 2, Ends of the respective optical fibers of the optical fiber 40 bundles are coupled in communication with each other by the coupling portion 106 to transmit the light emitted from the LED 50 through each optical fiber for an LCD using an optical fiber Backlight. The method according to claim 1 or 2, The ends of the respective optical fibers of the bundle of optical fibers 40 are coupled in communication with each other by the coupling section 106 so that the light emitted from the side surface of the upper plate 102 is incident through the ends of the coupling section 106. LCD backlight using the optical fiber, characterized in that transmitted through the optical fiber. The method according to any one of claims 1 to 5, The optical fiber bundle 40 rotates both ends of the optical fiber in opposite directions to form a twist layer 40b that destroys the cladding layer inside the optical fiber and emits light through the broken cladding layer. Dragon backlight.