KR100945482B1 - Backlight device using light emitting diode - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device using a light emitting diode, and more particularly, to a flat reflecting plate, a plurality of light emitting diode light sources provided on the reflecting plate, a transparent plate disposed above the light emitting diode light source, and the light emission of the bottom of the transparent plate. And a plurality of ink scattering patterns spaced apart from each other at a position corresponding to a diode light source, wherein the ink scattering patterns are divided into a central region and a peripheral region other than that, and the diameter of the central region is the ink scattering pattern position. It provides a backlight device, characterized in that formed to match the half width of the light emitting diode light intensity distribution in the.

Backlight, Scattering Pattern, Thinning

Description

Backlight device using light emitting diodes {BACKLIGHT APPARATUS HAVING LEDS}

The present invention relates to a backlight device using a light emitting diode, and more particularly, a transparent plate or a diffusion plate is installed on an upper portion of the light emitting diode light source, and the transparent plate or the diffusion plate corresponding to the light emitting diode light source is located at a predetermined position from the bottom. The present invention relates to a backlight device configured to more uniformly distribute light rays by forming a plurality of scattering patterns that transmit / reflect while scattering incident light.

BACKGROUND A backlight device of a liquid crystal display (LCD) using a light emitting diode, that is, an LED, is classified into an edge emitting method and a direct illumination method. Lateral emission sends light from the light source to the side and then redirects the light upwards using a reflector or scattering pattern to illuminate the liquid crystal panel. On the contrary, in the direct method, a light source is installed under the liquid crystal panel and the light is upwardly provided from the light source to provide illumination to the liquid crystal panel.

1 is a view schematically showing a conventional side-emitting backlight device. As shown in FIG. 1, the side emission type backlight device 10 includes a reflecting plate 12 having a scattering pattern 14 formed on an upper surface thereof, a light guide plate 16 disposed on an upper surface of the reflecting plate 12, and the light guide plate 16. LED light sources 18 and 20 in the form of rods disposed on both sides of the panel.

The LED light sources 18 and 20 emit light L laterally into the light guide plate 16, and the light L rotates in the light guide plate 16 and hits the scattering pattern 14 to be scattered upwards to guide the light guide plate 16. Back light is provided to the upper liquid crystal panel 22.

Such a side-emitting backlight device 10 has an advantage that the thickness thereof is small and the structure is simple. In addition, through the design of the reflective pattern 14 formed on the upper surface of the reflecting plate 12 or the lower surface of the light guide plate 16, there is an advantage that the intensity of light sent to the upper side can be uniformly adjusted. However, since the distance from which the light from the LED light sources 18 and 20 can be sent is limited, this structure is not applicable to the backlight of a large screen LCD.

2 is a view schematically showing a conventional direct type backlight device. As shown in FIG. 2, the direct type backlight device 30 includes a flat reflector 32, a rod-shaped LED light source 34 installed on the reflector 32, and a reflector disposed on the LED light source 34. Or a light shielding plate 36, a transparent plate 38 disposed at a predetermined distance G1 from the light blocking plate 36, and a diffusion plate 40 disposed at a predetermined distance G2 from the transparent plate 38. do.

The light source 34 emits light L1 and L2 mainly in a planar direction, and the light L1 emitted as described above is reflected by the reflector 32 and passes through the upper transparent plate 38. Diffusion to the desired uniformity at 40 provides backlight to the liquid crystal panel 42 on top. The other light L2 strikes the underside of the transparent plate 38 so that some L21 enters into the transparent plate 38 and provides a backlight to the liquid crystal panel 42 through the diffusion plate 40 thereon. On the other hand, the other part L22 of the light L2 is reflected from the transparent plate 38 to the reflecting plate 32 and then reflected from the reflecting plate 32 to the transparent plate 38 and diffuse in the same manner as the light L1. The backlight is provided to the liquid crystal panel 42 through the plate 40.

Since the backlight device 30 having the above structure can install a plurality of bar-shaped LED light sources 34 under the liquid crystal panel 42, there is an advantage that the backlight can be effectively provided to the large screen LCD.

However, since a predetermined distance G1 is required between the LED light source 34 and the transparent plate 38 and the transparent plate 38 and the diffusion plate 40 must also be maintained at a predetermined distance G2, The backlight device 30 has a disadvantage that the thickness is increased.

In detail, since the light L generated by the LED light source 34 is mainly reflected upward between the light blocking plates 36, the dark dark portions DA covered by the light blocking plates 36 are formed. In order to remove the dark portion DA and the bright lines, the transparent plate 38 and the diffusion plate 40 are mixed so that the light is mixed with each other until the light passes through the transparent plate 38 and enters the diffusion plate 40. There should be enough space (G2) more than a certain value between).

As such, in order to make the light propagating from the reflecting plate 32 to the liquid crystal panel 42 as a whole to be uniform, the above-described distances G1 and G2 must be maintained at a predetermined value or more. Increasing thickness is inevitable.

The present invention has been made to solve the above problems, an object of the present invention is to install a transparent plate or a diffusion plate on top of the light emitting diode light source and a predetermined position of the transparent plate or diffuser plate corresponding to the light emitting diode light source The present invention provides a backlight device configured to more uniformly distribute light rays by forming a plurality of scattering patterns that transmit / reflect while scattering light incident from the bottom.

In order to achieve the above object, the present invention provides a flat reflector, a plurality of light emitting diode light sources provided on the reflecting plate, a transparent plate disposed above the light emitting diode light source, and corresponding to the light emitting diode light source of the transparent plate. A plurality of ink scattering patterns spaced apart from each other at a position, wherein the ink scattering patterns are divided into a central region and a peripheral region other than the center region, and a diameter of the central region is the light emitting diode at the ink scattering pattern position. Provided is a backlight device, which is formed to match the half width of a light source illuminance distribution.

In this case, the ink scattering pattern may be formed on the bottom or top of the transparent plate.

In the backlight device, the ink scattering pattern is preferably reflected / transmitted in both the central area and the peripheral area, and the reflectance is reduced from the central area to the peripheral area.

In this case, the reflectance of the central region is preferably formed to be 10% or more higher than the reflectance of the peripheral region, and the reflectance of the ink scattering pattern may be adjusted by using a change in ink concentration or ink thickness.

In the backlight device, the reflection of the ink scattering pattern may be specular reflection, diffuse reflection, or a mixture thereof.

In the backlight device, the light emitting diode light source preferably generates at least one wavelength among red, green, blue, and UV wavelengths, and the light emitting diode light source may include one of yellow, red, and green wavelength-converting phosphors. May contain one or more.

The backlight device may further include a diffusion plate disposed on the transparent plate.

In order to achieve the above object, another embodiment of the present invention corresponds to a flat reflector, a plurality of light emitting diode light sources provided on the reflecting plate, a diffuser plate disposed above the light emitting diode light source, and the light emitting diode light source of the diffuser plate. And a plurality of ink scattering patterns spaced apart from each other at a position, wherein the ink scattering pattern is divided into a center region and a peripheral region other than that, and a diameter of the center region is the light emission at the ink scattering pattern position. Provided is a backlight device, which is formed to match the half width of a diode light intensity distribution.

In this case, the ink scattering pattern may be formed on the bottom surface or the top surface of the diffusion plate.

In the backlight device, the ink scattering pattern is preferably reflected / transmitted in both the central area and the peripheral area, and the reflectance is reduced from the central area to the peripheral area.

In this case, the reflectance of the central region is preferably formed to be 10% or more higher than the reflectance of the peripheral region, and the reflectance of the ink scattering pattern may be adjusted by using a change in ink concentration or ink thickness.

In the backlight device, the reflection of the ink scattering pattern may be specular reflection, diffuse reflection, or a mixture thereof.

In the backlight device, the light emitting diode light source preferably generates at least one wavelength among red, green, blue, and UV wavelengths, and the light emitting diode light source may include one of yellow, red, and green wavelength-converting phosphors. May contain one or more.

The backlight device may further include a transparent plate disposed under the diffusion plate.

The present invention provides a plurality of scattering patterns for transmitting / reflecting a transparent plate or a diffuser plate on an upper portion of a light emitting diode light source and scattering light incident from a lower portion at a predetermined position of the transparent plate or the diffuser plate corresponding to the light emitting diode light source. It is possible to provide a backlight device configured to distribute the light beam more uniformly by forming a.

In addition, the backlight device can increase the uniformity of the light emitted from the transparent plate, thereby reducing its thickness can be reduced.

Details of the technical configuration of the backlight device using the light emitting diode of the present invention will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity.

Example  One

A backlight device using a light emitting diode according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

3 is a cross-sectional view of a backlight device according to a first embodiment of the present invention, and FIG. 4 is a bottom view of an ink scattering pattern of the backlight device of FIG. 3.

First, as shown in FIG. 3, the backlight device 100 according to the first embodiment of the present invention is provided on the flat reflector 102 and the reflector 102 which are usually disposed on a substrate (not shown). A plurality of LED light source 104, a transparent plate 106 disposed at a predetermined interval from the LED light source 104 and a plurality of scattering patterns 108 disposed on the bottom surface of the transparent plate 106. At this time, each of the scattering pattern 108 is disposed at a position corresponding to the LED light source 104 of the lower side.

Meanwhile, the present exemplary embodiment further includes a diffusion plate (not shown) disposed above the transparent plate 106, that is, disposed between the transparent plate 106 and a liquid crystal panel (not shown). It is possible to increase the uniformity of light directed toward the liquid crystal panel at.

In addition, the present embodiment has been described for example a state in which the scattering pattern 108 is formed on the bottom of the transparent plate 106, which is not limited to this, as shown in FIG. 8 according to the characteristics and process conditions of the device In addition, a scattering pattern 108 may be formed on the upper surface of the transparent plate 106.

The reflector plate 102 is usually arranged in a thin film or sheet form on a substrate, and preferably has a Lambertian surface.

The LED light source 104 is preferably provided in the form of a plurality of LED arrays each of which a plurality of LEDs are arranged in a line. Meanwhile, in the present embodiment, three LED light sources 104 are illustrated, but this is only an example, and the LED light sources 104 may be configured with various numbers of two or four or more.

In addition, the LED light source 104 is preferably formed of an LED that generates at least one wavelength among red, green, blue, and UV wavelengths, which is one of yellow, red and green wavelength-converted phosphors. It can contain more.

The transparent plate 106 is a flat member having a constant thickness, and is made of transparent acrylic, polymethylmethacrylate (PMMA), plastic, glass, or the like.

The scattering pattern 108 is formed at a predetermined position on the bottom surface of the transparent plate 106 corresponding to the LED light source 104. Each scattering pattern 108 is circular having a predetermined radius r and spaced apart from each other at a predetermined distance d. At this time, the vertical axis passing through the focal point F of each LED light source 104, that is, the normal line la, is disposed to pass through the center C of the scattering pattern 108. In the present specification, an LED chip of the LED light source 104 is described as an example of a point light source. The angle θ formed between the imaginary line l1 connecting the edge of the scattering pattern 108 and the normal line la at the focal point F is determined by the spacing between the reflecting plate 102 and the transparent plate 106 and the scattering pattern ( 108) may be changed depending on the reflection / transmittance and the like.

In addition, the reflection of the scattering pattern 108 may be specular reflection, diffuse reflection, or a mixture thereof.

In addition, since the scattering pattern 108 is formed of ink, and the ink has scattering properties, the scattering pattern 108 may be scattered when the incident light is reflected / transmitted when coated / coated on the bottom of the transparent plate 106.

The scattering pattern 108 scatters the incident light when the incident light is reflected / transmitted. The scattering pattern 108 is divided into a central region 108a and a peripheral region 108b which is the remaining region except for the scattered pattern 108. In this case, the scattering pattern 108 is formed of both the central region 108a and the peripheral region 108b so that the reflectance is gradually reduced from the central region 108a to the peripheral region 108b. . Preferably, the reflectance of the central region 108a is formed to be at least 10% higher than the reflectance of the peripheral region 108b. The reflectance of the scattering pattern 108 may be adjusted by using a change in ink concentration or ink thickness.

In particular, the diameter 2r ₁ of the central region 108a according to the present invention is characterized in that it is formed to coincide with the full width at half maximum (FWHM) of the LED light intensity distribution at the scattering pattern 108 position.

Next, the scattering pattern 108 according to the present invention will be described in more detail with reference to FIGS. 5 and 6. FIG. 5A is a graph showing an illuminance distribution of the LED light source at the height of scattering pattern, b is a bottom view of the scattering pattern, and FIG. It is a graph showing uniformity.

Referring to FIG. 6, when the diameter of the peripheral region 108b of the scattering pattern is fixed at 10 mm and the diameter of the central region 108a is changed to 4 mm, 6 mm, 8 mm, and 10 mm, the uniformity of the backlight is 71%, It can be seen that 80%, 79%, 76%. In other words, it can be seen that the uniformity of the backlight is the highest when the diameter of the central region 108a of the scattering pattern is 6 mm, which is the half width of the LED light intensity distribution shown in FIG. 5.

Thus, as can be seen in FIG. 7, when light L1 is incident, the scattering pattern 108 reflects some light downward (not shown), while scattering the remaining light L11 and L12. It penetrates upwards. In this case, the light L11 passes directly through the transparent plate 106 and is emitted upward, and the light L12 is internally reflected from the upper surface of the transparent plate 106 to move inside the transparent plate 106 and then another scattering pattern. When it hits 108, it is reflected upward and is emitted above the transparent plate 106. In addition, a part L32 of the light L3 reflected downward from the bottom of the transparent plate 106 also roams inside the transparent plate 106 in the same manner as the light L12 described above, and then the upper portion of the transparent plate 106. Is released. On the other hand, some of the light (L2, L31, L33) is emitted to the upper portion of the transparent plate 106 as in the prior art.

In this way, since the light generated by the LED light source 104 is emitted upward through the partial region of the transparent plate 106 directly above the LED light source 104, the light is uniformly distributed in the entire region of the transparent plate 106. Is released. That is, the dark part DA and the corresponding bright line of the backlight device 30 of the related art described above with reference to FIG. 2 do not occur.

Example  2

9 and 10, a backlight device using a light emitting diode according to a second embodiment of the present invention will be described in detail. However, the description of the same parts as those of the first embodiment of the configuration of the second embodiment will be omitted, and only the configuration that is different from the second embodiment will be described in detail.

9 is a cross-sectional view of a backlight device according to a second embodiment of the present invention, and FIG. 10 is a cross-sectional view showing a modification of the backlight device according to a second embodiment of the present invention.

As shown in FIG. 9, the backlight device according to the second embodiment has the same configuration as the backlight device according to the first embodiment, except that the scattering pattern 108 is formed on the bottom surface of the diffusion plate 110 instead of the transparent plate. It differs from the first embodiment only in that it is formed.

Therefore, in the second embodiment, as in the first embodiment, the scattering pattern is divided into a center region and a peripheral region except for the first region, and the center region is formed to coincide with the half width of the LED light intensity distribution. The same action and effect can be obtained as in the example.

In addition, as in the modified example of the first embodiment, as shown in FIG. 10, the scattering pattern 108 may be formed on an upper surface of the diffusion plate 110 instead of the bottom surface thereof.

Meanwhile, the present embodiment further includes a transparent plate (not shown) disposed below the diffuser plate 110, that is, between the diffuser plate 110 and the LED light source 104 to diffuse in the LED light source 104. The uniformity of light directed to the plate 106 can be increased.

Although the preferred embodiments of the present invention have been described in detail above, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

1 is a schematic cross-sectional view of a conventional side emitting backlight device.

2 is a schematic cross-sectional view of a conventional direct backlight device.

3 is a cross-sectional view of a backlight device according to a first embodiment of the present invention;

4 is a bottom view of the scattering pattern of the backlight device of FIG.

5 is a diagram for explaining the diameter of the central region of the scattering pattern of FIG.

6 is a graph illustrating uniformity of a backlight device according to a change in diameter of a central region of the scattering pattern of FIG. 4.

FIG. 7 is a cross-sectional view illustrating the operation of the backlight device of FIG. 3. FIG.

8 is a sectional view showing a modification of the backlight device according to the first embodiment of the present invention.

9 is a sectional view of a backlight device according to a second embodiment of the present invention;

10 is a cross-sectional view showing a modification of the backlight device according to the second embodiment of the present invention.

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

100: backlight device 102: reflector

104: LED light source 106: transparent plate

108: scattering pattern 110: diffuser plate

Claims (36)

Flat reflector; A plurality of light emitting diode light sources provided on the reflecting plate; A transparent plate disposed above the light emitting diode light source; It includes a plurality of ink scattering patterns spaced apart from each other at a position corresponding to the light emitting diode light source of the bottom of the transparent plate, The ink scattering pattern is divided into a center region and a peripheral region except for the remaining region, and the diameter of the center region is formed to match the half width of the light emitting diode light intensity distribution at the ink scattering pattern position. The method of claim 1, And the ink scattering pattern is reflected / transmitted. The method of claim 2, The ink scattering pattern is a backlight device, characterized in that the reflectance is reduced from the central region to the peripheral region. The method of claim 3, And a reflectance of the central region is 10% or more higher than that of the peripheral region. The method of claim 3, The reflectance of the ink scattering pattern is adjusted by using a change in the density of the ink or the thickness of the ink. The method of claim 2, The reflection of the ink scattering pattern is a specular reflection, diffuse reflection or a mixture thereof. The method of claim 1, The light emitting diode light source is a backlight device, characterized in that at least one of the wavelength of red, green, blue, UV is generated. The method of claim 7, wherein The light emitting diode light source is a backlight device, characterized in that at least one of the phosphor is converted to any one of yellow, red, green. The method of claim 1, And a diffuser plate disposed on the transparent plate. Flat reflector; A plurality of light emitting diode light sources provided on the reflecting plate; A transparent plate disposed above the light emitting diode light source; It includes a plurality of ink scattering pattern spaced apart from each other at a position corresponding to the light emitting diode light source on the upper surface of the transparent plate, The ink scattering pattern is divided into a center region and a peripheral region other than the region, and the diameter of the center region is formed to match the half width of the light emitting diode light source illumination distribution at the ink scattering pattern position. Device. The method of claim 10, And the ink scattering pattern is reflected / transmitted. The method of claim 11, The ink scattering pattern is a backlight device, characterized in that the reflectance is reduced from the central region to the peripheral region. The method of claim 12, And a reflectance of the central region is 10% or more higher than that of the peripheral region. The method of claim 12, The reflectance of the ink scattering pattern is adjusted by using a change in the density of the ink or the thickness of the ink. The method of claim 11, The reflection of the ink scattering pattern is a specular reflection, diffuse reflection or a mixture thereof. The method of claim 10, The light emitting diode light source is a backlight device, characterized in that at least one of the wavelength of red, green, blue, UV is generated. The method of claim 16, The light emitting diode light source is a backlight device, characterized in that at least one of the phosphor is converted to any one of yellow, red, green. The method of claim 10, And a diffuser plate disposed on the transparent plate. Flat reflector; A plurality of light emitting diode light sources provided on the reflecting plate; A diffusion plate disposed above the light emitting diode light source; A plurality of ink scattering patterns spaced apart from each other at a position corresponding to the light emitting diode light source under the diffusion plate; The ink scattering pattern is divided into a center region and a peripheral region except for the remaining region, and the diameter of the center region is formed to match the half width of the light emitting diode light intensity distribution at the ink scattering pattern position. . The method of claim 19, And the ink scattering pattern is reflected / transmitted. The method of claim 20, The ink scattering pattern is a backlight device, characterized in that the reflectance is reduced from the central region to the peripheral region. The method of claim 21, And a reflectance of the central region is 10% or more higher than that of the peripheral region. The method of claim 21, The reflectance of the ink scattering pattern is adjusted by using a change in the density of the ink or the thickness of the ink. The method of claim 20, The reflection of the ink scattering pattern is a specular reflection, diffuse reflection or a mixture thereof. The method of claim 19, The light emitting diode light source is a backlight device, characterized in that at least one of the wavelength of red, green, blue, UV is generated. The method of claim 25, The light emitting diode light source is a backlight device, characterized in that at least one of the phosphor is converted to any one of yellow, red, green. The method of claim 19, The backlight device further comprises a transparent plate disposed under the diffusion plate. Flat reflector; A plurality of light emitting diode light sources provided on the reflecting plate; A diffusion plate disposed above the light emitting diode light source; It includes a plurality of ink scattering pattern spaced apart from each other at a position corresponding to the light emitting diode light source on the upper surface of the diffusion plate, The ink scattering pattern is divided into a center region and a peripheral region other than the region, and the diameter of the center region is formed to match the half width of the light emitting diode light source illumination distribution at the ink scattering pattern position. Device. The method of claim 28, And the ink scattering pattern is reflected / transmitted. The method of claim 29, The ink scattering pattern is a backlight device, characterized in that the reflectance is reduced from the central region to the peripheral region. The method of claim 30, And a reflectance of the central region is 10% or more higher than that of the peripheral region. The method of claim 30, The reflectance of the ink scattering pattern is adjusted by using a change in the density of the ink or the thickness of the ink. The method of claim 29, The reflection of the ink scattering pattern is a specular reflection, diffuse reflection or a mixture thereof. The method of claim 28, The light emitting diode light source is a backlight device, characterized in that at least one of the wavelength of red, green, blue, UV is generated. The method of claim 34, wherein The light emitting diode light source is a backlight device, characterized in that at least one of the phosphor is converted to any one of yellow, red, green. The method of claim 28, The backlight device further comprises a transparent plate disposed under the diffusion plate.

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