KR100644700B1 - Side emitting device, back light system using the same as a light source and liquid display apparatus employing it - Google Patents

Abstract

A side emitting device, a backlight system using the side emitting device as a light source, and an LCD adopting the backlight system are provided to increase the amount of light advancing in a side direction, thereby making the distribution of the light uniform, by using a side emitter. A side emitting device comprises an emitting element(30) having a single LED(Light Emitting Diode) chip or a plurality of LED chips and a side emitter(50) for making a light incident from the emitting element advance in a side direction. The side emitter includes a dome-shaped body(51) for refracting and transmitting the incident light, and a corn-shaped protrusion(53) protruded from the dome-shaped body. The corn-shaped protrusion internally reflects, refracts, and outputs the light passing through the center portion of the dome-shaped body.

Description

Side emitting device, back light system using the same as a light source and liquid display apparatus employing it}

1 is a side cross-sectional view schematically showing a side emitter of a side emitting LED disclosed in US Pat. No. 6,679,621.

FIG. 2 schematically shows the traveling path distribution of light exiting from the side emitter of a conventional side emitting LED as shown in FIG. 1.

3 schematically shows a side light emitting device according to a preferred embodiment of the present invention.

4 shows a traveling path of light in the side light emitting device of FIG. 3.

FIG. 5 shows another embodiment of a light emitting device applied to the side light emitting device of FIG. 3.

6 schematically shows a side light emitting device according to another embodiment of the present invention.

FIG. 7 shows a traveling path of light in the side light emitting device of FIG. 6.

FIG. 8 shows a refraction of light in a domed cap used in a general light emitting diode as a comparative example.

9 is a graph illustrating an intensity distribution of light emitted from a side light emitting device according to an exemplary embodiment of the present invention described with reference to FIGS. 3 and 4.

FIG. 10 is a graph illustrating an intensity distribution of light emitted from a side light emitting device according to another exemplary embodiment of the present invention described with reference to FIGS. 6 and 7.

FIG. 11 is a graph illustrating an intensity distribution of light emitted through a cap of a conventional light emitting device according to the comparative example of FIG. 8.

12 schematically shows an embodiment of a backlight system in which the side light emitting devices according to the invention are arranged in an array.

13 schematically shows a liquid crystal display device having a backlight system according to the present invention.

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

10,100 ... side light emitting device 30 ... light emitting element

31,31a, 31b, 31c ... light emitting chip 50,150 ... side emitter

51.Body part 51a ... Refractive transmissive surface

53,153 Projection 55 Cylindrical

57 conical section 200 backlight system

240 ... Diffuse plate 300 ... Liquid crystal panel

The present invention relates to a side light emitting device, a backlight system using the same as a light source, and a liquid crystal display device employing the same.

A liquid crystal display, which is one of flat panel displays, is a light-receiving display device that itself does not emit light to form an image, but light is incident from the outside to form an image. The backlight system is installed on the back of the liquid crystal display to irradiate light.

The backlight system has a direct light type for irradiating the liquid crystal panel with light from a plurality of light sources provided directly below the liquid crystal display device and a sidewall of a light guide panel (LGP) according to the arrangement of the light sources. It can be broadly classified into an edge light type for transmitting light from the installed light source to the liquid crystal panel.

Light emitting diodes (LEDs) that emit light of Lambertian as a point light source may be used in the direct-emitting backlight system. When the light emitted from the LED is diffused by the diffuser plate and irradiated onto the liquid crystal panel, to prevent the color light of the LED from being directly visible on the diffuser plate, the light emitted from the LED can be propagated slightly laterally and incident on the diffuser plate. Side emitting LED is required.

U. S. Patent No. 6,679, 621 discloses a side emitting LED. The US patent discloses a side emitting LED designed to emit light from the LED junction to the side by means of a device called a side emitter.

The conventional side emitter disclosed in this US patent is divided into a part causing total reflection and a part causing refraction. That is, the conventional side emitter disclosed in the US patent and the funnel-shaped reflecting surface inclined with respect to the central axis, and the first refractive surface inclined with respect to the central axis so as to refractively transmit the light reflected from the reflecting surface and And a convex or serrated second refractive surface connected from the bottom surface to the first refractive surface.

By the way, since the side part of the side emitter of this structure is difficult to process, the actual product is made of the structure shown in FIG. The side emitter structure of FIG. 1 is also disclosed in this US patent.

Referring to FIG. 1, a conventional side emitter 1 refracts and transmits a funnel-shaped reflecting surface 3 inclined with respect to a central axis C ′, and light reflected and incident from the reflecting surface 3. The first refractive surface 5 inclined with respect to the central axis C ', and the second refractive surface 7 of the convex shape connected from the bottom surface 9 to the first refractive surface 5.

Light incident from the side of the LED (not shown) into the side emitter 1 and traveling toward the reflecting surface 3 is mostly totally reflected at the reflecting surface 3 to the first refractive surface 5, and the first refractive surface 5 Permeate through) and progress in the lateral direction. Further, the light incident from the LED side into the side emitter 1 and incident on the convex second refractive surface 7 passes through the second refractive surface 7 and travels in a lateral direction.

However, according to the conventional side emitter 1 as described above, the area A near the central axis C 'of the funnel-shaped reflective surface 3 passes through the reflective surface 3 without total reflection. There are many lights. Thus, as shown in Fig. 2, there are a lot of lights coming up directly. 2 is a simulation result showing a traveling path of light incident on the reflection surface 3.

In FIG. 2, the light rays of the region B represent light rising directly through the reflection surface 3 directly from the region A without total reflection.

These lights have a devastating effect on the backlight. That is, due to these lights, the part where the side emitter 1 is located may look bright. Therefore, these lights adversely affect the composition of the screen with even brightness, thus deteriorating the backlight characteristics.

In order to remedy this problem, it is required to place several optical elements, for example pattern diffuse reflectors or mirrors, above the side emitter 1. In addition, because of the light in the region B as described above, the thickness of the backlight is increased in order to diffuse the light sufficiently to eliminate the problem that the portion where the side emitter 1 is located is bright.

It is also possible to dig deeper into the A region so that a large portion of total reflection occurs, but this method is not easy in the manufacturing process.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and provides a side light emitting device having an improved structure to further enhance the amount of light traveling in a lateral direction, a backlight system using the same as a light source, and a liquid crystal display device employing the same. Its purpose is to.

According to an aspect of the present invention, there is provided a side light emitting device comprising: a light emitting device including a single light emitting device chip or a plurality of light emitting device chips for irradiating light in at least two wavelength ranges; And a side emitter configured to propagate light incident from the light emitting device in a lateral direction, wherein the side emitter has a dome-shaped refractive transmission surface for refracting and transmitting light incident from the light emitting device into the side emitter. Wealth; Located in the protruding portion on the body portion, the horn-shaped protrusions having a pointed shape to be internally reflected and then refracted by the light traveling through the central portion of the body portion; characterized in that it comprises a.

The horn-shaped protrusion preferably has a conical portion.

The horn-shaped protrusion may further include a cylindrical portion between the body portion and the cone portion.

A backlight system according to the present invention for achieving the above object comprises: a side light emitting device array having side light emitting devices according to the present invention having at least one of the above mentioned feature points arranged in an array on a base plate; And a transmission diffuser plate positioned above the side light emitting device array to diffusely transmit incident light.

A backlight system according to the present invention for achieving the above object is a liquid crystal panel; And the backlight system for irradiating light to the liquid crystal panel.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a side light emitting device and a backlight system using the same as a light source and a liquid crystal display device employing the same.

FIG. 3 schematically shows a side light emitting device 10 according to a preferred embodiment of the invention, and FIG. 4 shows a path of light propagation in the side light emitting device 10 of FIG. 3.

3 and 4, the side light emitting device 10 according to the present invention includes a light emitting device 30 for emitting light and a side for propagating light incident from the light emitting device 30 in a lateral direction. It comprises a side emitter (50).

The light emitting element 30 is disposed on the central axis of the side emitter 50. The light emitting device 30 includes a light emitting device chip 31 that generates light, and is coupled to the side emitter 50 with the light emitting device chip 31 disposed on the base 35. . The light emitting device chip 31 may be a light emitting diode (LED) chip or an organic light emitting diode (OLED) chip that emits Lambertian light.

Preferably, the light emitting device chip 31 and the side emitter 50 are in close contact with each other. As such, by closely contacting the light emitting device chip 31 and the side emitter 50, the amount of light generated in the light emitting device chip 31 and entering the side emitter 50 may be maximized.

Meanwhile, instead of the single light emitting device chip 31, the light emitting device 30 may include a plurality of light emitting device chips that emit light in at least two wavelength ranges, as illustrated in FIG. 5.

Referring to FIG. 5, the light emitting device 30 includes, for example, three first light emitting device chips 31a, two second light emitting device chips 31b, and three third light emitting device chips 31c. can do.

Here, the number or arrangement of the light emitting device chips 31a, 31b and 31c for each wavelength range is a desired color temperature range in consideration of the amount of light emitted from the light emitting device chips 31a, 31b and 31c for each wavelength range. It can be suitably configured according to. The arrangement of the light emitting device chips 31a, 31b, 31c that emit light in a plurality of wavelength ranges, and the number of arrangements can be configured in various ways to set the light emitting device 30 is advantageous to color implementation And, from the manufacturer's point of view, there is a big advantage in color selectivity. In addition, even when the light emitting device 30 is configured to have a multi-chip structure, the size of the light emitting device 30 does not change significantly compared to the light emitting device having a single chip, so there is no concern about volume increase.

The side emitter 50 includes a transparent body 51 made of a transparent material, for example, a transparent plastic material, and a horn-shaped protrusion 53 having a pointed shape positioned to protrude from the body 51.

The body portion 51 has a dome-shaped refractive transmission surface 51a for refracting the light incident from the light emitting device 30 into the side emitter 50.

The protrusion 53 internally reflects the light traveling through the central portion of the body 51 and is then refracted. The protrusion 53 may have a conical portion 57. In this embodiment, the protrusion 53 further comprises a cylindrical portion 55 between the body portion 51 and the conical portion 57.

Light emitted from the light emitting device 30 and incident on the body part 51 passes through the body 51 medium, and then is emitted to the outside through the refractive-transmitting surface 51a. At this time, the light is refracted by the refractive-transmission surface 51a, and as shown in FIG. 4, the light travels in a lateral direction and spreads widely. Here, when the axis perpendicular to the central axis across the center of the light emitting element 30 and the side emitter 50 is a horizontal axis, the lateral direction includes a direction approaching the horizontal axis or at a predetermined angle to the horizontal axis. Is considered.

On the other hand, the light emitted from the light emitting element 30 and proceeds to the central portion of the medium of the body portion 51 (that is, a predetermined range including the central axis) is located to protrude on the central axis of the body portion 51 It is incident on the protrusion 53.

When the light traveling to the center portion of the body portion 51 is emitted from the body portion 51 and proceeds upward, the area where the light emitting device 30 is positioned is brighter than the rest of the conventional portions. May appear. The protrusion 53 allows the majority of the light traveling in the central portion of the body portion 51 to travel laterally.

Light incident on the protrusions 53 is internally reflected at least once in the cylindrical portion 55 or the conical portion 57, more preferably totally internally reflected and then refracted at the plane of the conical portion 57 and exited outward. .

For example, the light incident from the body portion 51 toward the protrusion 53 and traveling to the surface of the cylindrical portion 55 is internally reflected at the surface and proceeds to the conical portion 57 and the conical portion 57. It passes through the surface of and exits to the outside. Further, the light entering the protruding portion 53 from the body portion 51 and advancing from the conical portion 57 is internally reflected in a predetermined region of the surface of the conical portion 57 and proceeds to another region of the surface. It penetrates the surface and exits to the outside.

By the configuration of the protrusion 53 as described above, the light traveling from the body portion 51 toward the protrusion 53 does not proceed straight upward, but as shown in FIG. 4, the conical portion 53 of the protrusion 53 is shown. It is refracted in the plane of) and proceeds in an approximately lateral direction to spread.

Thus, the side light emitting device 10 with the side emitter 50 as described above can greatly reduce the light coming directly up and greatly enhance the light traveling in the lateral direction.

Meanwhile, FIG. 6 schematically shows a side light emitting device 100 according to another embodiment of the present invention, and FIG. 7 shows a propagation path of light in the side light emitting device 100 of FIG. 6. Here, the members substantially the same as in the previous embodiment are denoted by the same reference numerals and the repeated description thereof will be omitted.

In the side light emitting device 100 according to another embodiment of the present invention, the side emitter 150 includes a body portion 51 and a protrusion 153, characterized in that the protrusion 153 consists of only a conical portion. have.

Light emitted from the light emitting element 30 and traveling to the central portion of the medium of the body portion 51 (ie, the predetermined range including the central axis) is conical to protrude on the central axis of the body portion 51. It is incident to the protrusion 153.

Light incident on the protrusion 153 is internally reflected at least once in a given area of the cone face, more preferably totally internally reflected and then proceeds to another area of the cone face and refracted in the area of the face to the outside. It is emitted.

Even when the protrusion 153 is configured as described above, the light traveling from the body 51 toward the protrusion 153 does not proceed straight upward, but as shown in FIG. 7, the conical surface of the protrusion 153 is shown. It is refracted at and spreads in an approximate lateral direction.

Thus, the side light emitting device 100 with the side emitter 150 as described above can greatly reduce the light coming directly up and similarly enhance the light traveling in the lateral direction similarly to the previous embodiment. have.

FIG. 8 shows a refraction of light in a domed cap 170 used in a general light emitting diode as a comparative example. When a light emitting diode (not shown) is positioned on the central axis of the cap 170, the light emitted from the light emitting diode and incident on the cap 170 travels through the cap 170 medium and the surface of the cap 170. It is spread through the refraction. At this time, as can be seen in Figure 8, there is a considerable amount of light coming directly up.

FIG. 9 is a graph illustrating an intensity distribution of light emitted from the side light emitting device 10 according to an exemplary embodiment of the present invention described with reference to FIGS. 3 and 4. FIG. 10 is a graph illustrating an intensity distribution of light emitted from the side light emitting device 100 according to another exemplary embodiment of the present invention described with reference to FIGS. 6 and 7. FIG. 11 is a graph illustrating an intensity distribution of light emitted through the cap 170 of the conventional light emitting device according to the comparative example of FIG. 8.

9 to 11, the horizontal axis represents an angle with respect to the central axis of the side emitter or cap, and the vertical axis represents intensity at an angular position with respect to each central axis when the total amount of light is 100. As can be seen from the comparison of Figs. 9 and 10 with Fig. 11, according to the side light emitting device 10 (100) according to the present invention, the intensity of light in the angular range close to the central axis is a general dome cap ( Significantly smaller compared to a light emitting device using 170). This means that when using the side light emitting device 10 (100) according to the present invention, the amount of light rising immediately above is greatly reduced compared to the case of using a general light emitting device.

Therefore, when the side light emitting device 10, 100 according to the present invention as described above is applied to a backlight system and a liquid crystal display device employing the same, it is possible to spread the light wide enough while sufficiently reducing the amount of light rising directly above. In addition, it is possible to obtain a screen with an even brightness distribution while making the backlight system thin enough.

Figure 12 shows schematically an embodiment of a backlight system 200 in which the side light emitting devices according to the invention are arranged in an array. 12 illustrates a case in which the side light emitting device 10 according to an embodiment of the present invention is applied to the backlight system 200, and the side light emitting device 100 according to another embodiment of the present invention is a backlight system. The embodiment applied to 200 can be sufficiently inferred from the foregoing description and FIG. 12, and thus the illustration and description thereof are omitted.

Referring to FIG. 12, a backlight system 200 according to an exemplary embodiment may include a plurality of side light emitting devices 10 arranged in an array on a base plate 201 and above the side light emitting device 10. And a transmission diffuser plate 240 positioned to diffusely transmit incident light.

The base plate 201 serves as a substrate for installing the plurality of side light emitting devices 10 in an array. The base plate 201 may be a printed circuit board (PCB) for driving the side light emitting device 10. Here, a printed circuit board (PCB) for driving the side light emitting device 10 may be provided separately from the base plate 201.

As described above with reference to FIGS. 3 to 5, the side light emitting device 10 emits most of the emitted light emitted from the light emitting device chip 31 positioned downwardly by the side emitter 50. Let's do it.

In this case, when the single light emitting device chip 31 is used, the array of the plurality of side light emitting devices 10 may have, for example, a structure in which side light emitting devices that emit R, G, and B color lights are alternately arranged. . In this case, a light emitting element chip 31 for generating R, G or B color light is used for the side light emitting device 10, respectively. In addition, as described with reference to FIG. 5, instead of the single light emitting device chip 31, the light emitting device 30 of the side light emitting device 10 emits light of at least two wavelength ranges. (B) 31b, 31c, white light is emitted from each side light emitting device 10.

As described above, the array of the plurality of side light emitting devices 10 is formed in a structure in which side light emitting devices for each color light are alternately arranged using light emitting diode chips that generate R, G, and B color light, or each side light emitting device 10 Is configured to emit white light, the liquid crystal display device to which such a backlight system 200 is applied can display a color image.

Meanwhile, the backlight system 200 according to the present invention may further include a reflective diffuser plate 210 positioned below the side light emitting device 10 to diffuse and reflect incident light upward.

The reflective diffuser plate 210 is placed on the base plate 201 so that it can be located below the side light emitting device 10. To this end, a plurality of holes are formed in the reflective diffuser plate 210 through which the plurality of side light emitting devices 10 can be passed, and the reflective diffuser plate 210 has the side light emitting device 10 fitted into the holes. The furnace base plate 201 is installed.

If the reflective diffuser 210 is further provided as described above, the amount of light used as illumination light of the backlight system 200 may be further increased.

The transmission diffusion plate 240 is positioned to be spaced apart from the side light emitting device 10 by a predetermined interval. The transmission diffusion plate 240 diffuses and transmits incident light.

In this case, when the transparent diffusion plate 240 is too close to the side light emitting device 10, the portion where the side light emitting device 10 is positioned may be brighter than the rest of the light emitting device, and thus the brightness uniformity may be deteriorated. In addition, the thickness of the backlight system 200 increases as the transmission diffuser 240 is spaced apart from the side light emitting device 10. Therefore, the separation distance between the transmission diffuser plate 240 and the lower part of the backlight system 200 including the side light emitting device 10 is minimized so that the light can be mixed as well as desired by the light diffusion. It is preferable to be determined.

Of course, the backlight system 200 according to the present invention can spread the light widely, and since the side light emitting device 10 according to the present invention which greatly reduces the amount of light proceeding directly is used as a light source, the conventional side light emission Compared to a general backlight system using a general LED having an LED or a dome cap as a light source, even if the distance between the light source and the transmission diffuser above is reduced, brightness uniformity can be ensured, so that the overall thickness of the backlight system 200 is reduced. Can be reduced.

On the other hand, even when the side light emitting device 10 or 100 according to the present invention is used, since some of the light proceeds directly above the side emitter 50 or 150, the brightness of the backlight system 200 is further reduced, In order to ensure uniformity, the backlight system 200 according to the present invention is adapted to reflect the light emitted directly upward from the side light emitting device 10 or 100 without directly traveling the side of the side light emitting device 10 or 100. An optical plate (not shown) having a plurality of reflective mirrors (not shown) corresponding to the arrangement may be further provided between the side light emitting device 10 or 100 and the transmission diffusion plate 240. The optical plate is installed spaced apart from the side light emitting device 10 or 100. The optical plate may be made of a transparent PMMA that transmits incident light as it is, or may be made of a transmission diffusion plate.

In the case of further comprising an optical plate made of a transmission diffusion plate as described above, light diffusion may occur more sufficiently than in the case where only the transmission diffusion plate 240 is provided, so that the transmission diffusion plate 240 and the side light emitting device 10 are provided. The thickness of the backlight system 200 may be reduced by further reducing the distance between the gaps, that is, the gap between the transparent diffusion plate 240 and the lower portion of the backlight system 200 according to the present invention.

Meanwhile, the backlight system 200 according to the present invention may further include a brightness enhancement film (BEF) 250 for improving the linearity of the light emitted from the transmission diffusion plate 240. In addition, the backlight system 200 according to the present invention may further include a polarization enhancement film (270) for increasing polarization efficiency.

The brightness enhancing film 250 may improve the brightness by increasing the straightness of the light by refracting and condensing the light emitted from the transmission diffusion plate 240.

The polarization enhancement film 270 transmits light of p-polarized light and reflects light of s-polarized light, for example, so that most of the incident light is emitted as one polarized light, for example, p-polarized light.

13 schematically shows a liquid crystal display device having a backlight system 200 according to the present invention.

Referring to FIG. 13, a liquid crystal display device employing the backlight system 200 according to the present invention includes a backlight system 200 and a liquid crystal panel 300 provided on the backlight system 200. As is well known, the liquid crystal panel 300 has a polarization change of light passing through the liquid crystal layer by injecting light of one linearly polarized light into the liquid crystal layer of the liquid crystal panel and changing the direction of the liquid crystal director by electric field driving. By this, image information and the like are displayed. The liquid crystal panel 300 is connected to the driving circuit unit. Here, in the field of the liquid crystal display device, since a specific configuration of the liquid crystal panel 300 and a display operation by driving a circuit are widely known, a detailed description and illustration thereof will be omitted.

Therefore, as light incident on the liquid crystal panel 300 becomes single polarized light, the light utilization efficiency can be improved. Thus, when the backlight system 200 includes the polarization improving film 270 as described above, it is possible to improve the light efficiency. It is possible.

As described above, the backlight system 200 according to the present invention has a side light emitting device 10 or 100 which can be widely spread by emitting most of the light in a lateral direction with a point light source arranged in an array, so that the backlight It is possible to obtain a backlight system 200 that has a sufficiently thin thickness of the system 200 while having an even distribution of light intensity across the entire surface.

Therefore, when the backlight system 200 according to the present invention as described above is applied to a liquid crystal display device, for example, an LCD TV, it is possible to implement a high quality image having a uniform brightness of the full screen.

The side light emitting device according to the present invention as described above is configured to greatly reduce the light emitted from the light emitting device chip and proceeds directly up, thereby further increasing the amount of light traveling in the lateral direction.

Therefore, the backlight system using the side light-emitting device of the present invention as a point light source can obtain high-quality light with an even intensity distribution over the entire surface of the backlight system, and its thickness can be reduced as compared with the prior art. In addition, a liquid crystal display device, for example, an LCD TV, to which the backlight system is applied, may implement a high-quality image having a uniform brightness of a full screen.

Claims (5)

A light emitting device comprising a single light emitting device chip or a plurality of light emitting device chips for irradiating light in at least two wavelength ranges; And a side emitter configured to propagate light incident from the light emitting device in a lateral direction. The side emitter, A body portion having a dome-shaped refractive transmission surface for refracting the light incident from the light emitting element into the side emitter; And a horn-shaped protrusion protrudingly positioned on the body part to internally reflect light propagating through the central portion of the body part and then to be refracted and output. The side-emitting device as claimed in claim 1, wherein the horn-shaped protrusion has a conical portion. 3. The light emitting device of claim 2, wherein the horn-shaped protrusion further comprises a cylindrical portion between the body portion and the conical portion. A side light emitting device array in which the side light emitting devices of any one of claims 1 to 3 are arranged in an array on a base plate; And a transmission diffuser plate positioned above the side light emitting device array to diffusely transmit incident light. A liquid crystal panel; And a backlight system for irradiating light to the liquid crystal panel.

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