KR101196909B1 - Backlight unit of direct illumination type - Google Patents

Abstract

According to the present invention, a plurality of light sources, a light guide plate, a top surface or a bottom surface of a light guide plate, which are disposed above the light sources, are formed with a plurality of inclined grooves having an inclined surface that reflects the light from the light source on the bottom surface and then proceeds inwardly. A plurality of light splitters which are spaced apart from each other and guide the light traveling inside the light guide plate to the outside of the light guide plate by any one or a plurality of internal reflections, refractions and scattering, and exits from the light source. Provided is a direct-type backlight unit including a light mixing light guide plate which enters light into the inside, diffuses or mixes light, and then enters the inclined groove of the light guide plate.
Therefore, it is possible to manufacture a thin thin, and in addition, it is possible to effectively eliminate the bright spots and spots generated when placing a plurality of light sources in a direct type to obtain a uniform illumination, and to drive difficult regional division in the direct type It enables high image quality and energy saving, and the light is mixed enough before entering the light guide plate through the light mixing light guide plate, so that it can be completely eliminated at the bright point to achieve high uniformity. Better image quality than ever.

Description

Backlight unit of direct illumination type

The present invention relates to a direct type backlight unit, and more particularly, to a direct type backlight unit in which a light source is disposed directly below a liquid crystal panel for a liquid crystal display (LCD).

In general, a backlight unit for a liquid crystal display device includes a direct illumination type in which a light source is arranged directly under a liquid crystal panel, and an edge type in which a light source is provided at a side of a light guide plate, depending on a form of a light source constituting the backlight. (Edge illumination type).

Among these, the direct type backlight unit is capable of large screens of liquid crystal panels, and local dimming technology can be performed for each location according to the brightness of an image. In addition, in recent years, in order to achieve high energy efficiency and high image quality, LED (Light Emitting Diode) instead of CFL or External Electrode Fluorescence Lamp (EEFL) commonly used in the related art. It is a recent trend to use as a new light source.

1 shows a liquid crystal display device employing a conventional direct type backlight unit using LED as a light source.

Referring to the drawings, a conventional direct type liquid crystal display device includes a liquid crystal panel 40 including a liquid crystal pixel serving as a light valve by controlling light transmittance and a backlight unit for supplying light to the liquid crystal panel 40 ( 10).

The liquid crystal panel 40 includes a rear glass substrate having a TFT (Thin Film Transistor), a front glass substrate having a color filter, a plurality of liquid crystal pixels installed between the rear glass substrate and the front glass substrate, and a polarizing sheet attached to the rear glass substrate. A, a polarizing sheet B, etc. attached to the front glass substrate. Reference numeral 21 denotes a reflective surface.

The backlight unit 10 reflects the light source assembly portion 20 including the CCFL, the EEFL, or the LED, and the light emitted from the light source 11 from a reflector located below the light source, or evenly mixes the light and adjusts the viewing angle. The optical sheet 30 is sprayed into a plurality of liquid crystal pixels. The optical sheet 30 basically consists of a diffusion plate 31, a diffusion sheet 32, a light collecting sheet 33, a reflective polarizing sheet 34, and a protective film 35 to optimize the viewing angle and brightness. Adjust to.

In the case of the direct type backlight unit, a method of narrowing the distance (H; see FIG. 1) between the light source and the liquid crystal panel is sought. However, when the light source is an LED, the distance H between the liquid crystal panel and the LED is short. The light mixing effect is not good, the bright spots or spots appear on the screen, this phenomenon is adopted by the thin backlight becomes more severe the shorter the distance (H).

In recent years, however, LEDs have been adopted as light sources, and all liquid crystal displays have been manufactured in a thin plate shape.

Figure 2 is a cross-sectional view of a conventional edge-type backlight unit, the edge-type backlight unit is mainly applied to a notebook or a monitor, but recently shows an edge-type backlight unit also used in the backlight of a large screen LCD TV.

Referring to the drawings, a light source 11 such as an LED is disposed on one side or both sides of the edge of the light guide plate 50, and the light is upwardly directed by the light scattering pattern 60 disposed on the bottom or top surface of the light guide plate 50. Will be emitted. In this case, the brightness and the viewing angle are optimally adjusted by the optical sheet 30 such as the diffusion sheet 32, the light collecting sheet 33, and the polarization reflecting sheet 34 positioned on the light guide plate 50. Such edge type backlight can be manufactured very thinly compared to the direct type, but it has a disadvantage in that image quality is low and energy consumption is consumed due to the impossibility of local driving. Reference numeral 51 denotes a reflective sheet.

The direct type or edge type backlight may be used as a general lighting device as a flat panel lighting device. In the case of a flat panel lighting apparatus using LED as a light source, the edge type has a problem that the number of LEDs is limited and sufficient brightness cannot be achieved. In addition, in the case of the direct type, there is a problem that the distance H between the LED and the diffusion plate is too large and the size of the lighting device is too large.

The present invention can be manufactured in a thin thin, and at the same time can effectively eliminate the bright spots and spots generated when placing a plurality of light sources in a direct type to obtain a uniform illumination, using a high-division division drive It is an object of the present invention to provide a direct backlight unit capable of realizing contrast and saving energy.

The present invention provides a light guide plate and a plurality of light sources disposed on the light sources, the plurality of inclined grooves having an inclined surface which reflects the light from the light source on the lower surface thereof and then proceeds inwardly. A direct backlight disposed on an upper surface or a lower surface and including a plurality of light splitters that are spaced apart from each other and guide the light traveling through the inside of the light guide plate to the outside of the light guide plate by any one or a plurality of internal reflection, refraction, and scattering. Provide the unit.

The direct type backlight unit according to the present invention provides the following effects.

First, compared to a conventional LED backlight using a spaced space between the light source and the diffuser plate and using the diffuser plate, the diffusion sheet and the light collecting sheet, it is possible to effectively dissipate heat generated in the LED while achieving a much thinner thickness.

Secondly, it is possible to drive difficult regional division in the direct type, so that high image quality and energy saving can be achieved, high contrast ratio can be achieved, and power consumption can be reduced.

Third, it is suitable for a slim LCD backlight by effectively removing the bright spots appearing in the point light source LED to obtain uniform light.

Fourth, since the light having an appropriate viewing angle and vertical luminance by the plurality of light splitters illuminates the liquid crystal panel, it is not necessary to provide a light collecting sheet, which is advantageous in cost reduction.

Fifth, when inducing the light of the RGB LED into the light guide together, it is possible to achieve a sufficient color mixing to eliminate the color blur effect, and at the same time to achieve a high image quality by the RGB LED light.

Sixth, it can be used as a flat LED lighting.

Seventh, by allowing the light to be sufficiently mixed before entering the light guide plate can be completely eliminated in the bright spot to achieve a high uniformity, RGB LED can be used to achieve a much better image quality than when using a white LED.

1 is a cross-sectional view of a liquid crystal display device employing a conventional direct type backlight unit.
2 is a cross-sectional view showing a conventional edge type backlight unit.
3 is a cross-sectional view illustrating a direct type backlight unit according to a first embodiment of the present invention.
4 is a diagram illustrating an arrangement of a light source in FIG. 3.
5 is a perspective view when viewed from the bottom to show the inclined groove of FIG.
FIG. 6 is a perspective view illustrating the light guide plate and the light splitter of FIG. 3.
FIG. 7 is a perspective view illustrating the optical branch body of FIG. 6. FIG.
8 is a perspective view illustrating another embodiment of the optical branch body of FIG. 6.
FIG. 9 is a cross-sectional view illustrating a light induction flow caused by the inclined groove and the optical branch body of FIG. 3.
FIG. 10 is a plan view illustrating a case in which a hemispherical optical branch structure is included in the light guide plate of FIG. 3.
11 to 14 are plan views illustrating the light guide plate and the inclined groove of FIG. 3.
FIG. 15 is a cross-sectional view illustrating a case in which a photoconductor is further provided in FIG. 3.
16 is a cross-sectional view illustrating a direct type backlight unit according to a third embodiment of the present invention.
17 is a cross-sectional view illustrating another embodiment in which a light collecting sheet is applied instead of a diffusion sheet in the direct backlight unit of FIG. 16.
FIG. 18 is a cross-sectional view illustrating a direct light guide type backlight unit according to a fourth embodiment of the present invention. FIG.
19 is a cross-sectional view illustrating a direct type backlight unit according to a fifth embodiment of the present invention.
FIG. 20 illustrates a perspective view of the light mixing light guide plate of FIG. 19.
21 is a sectional view showing a sixth embodiment of the present invention.
22 and 23 are perspective views illustrating a structure of converting a light source in FIG. 21.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, referring to FIG. 3, the direct type backlight unit 100 according to the first embodiment of the present invention includes a light guide plate 130 and a light splitter in which a plurality of light sources 110 and a plurality of inclined grooves 131 are formed. (140,210,340,142,144).

The light sources 110 are disposed at positions corresponding to lower portions of the inclined grooves 131 and the vertical direction (up and down direction), respectively. Preferably, the light source 110 and the inclined groove 131 may be aligned with respect to the vertical direction. Referring to FIG. 4, the light sources are disposed on the light source back plate 120, and the light source back plate 120 includes a plurality of light source cups 121 for mounting the light sources 110 thereon. It is. Here, the light source back plate 120 is coated on both sides and the bottom surface of the light source cup 121 in order to increase light efficiency. The light sources 110 are arranged to be spaced apart from each other in the lateral direction of the light source rear plate 120, and a plurality of light sources 110 are regularly spaced apart from each other in a straight line shape along the light source cup 120. . Here, the light source 110 may be a white light LED or an R, G, B LED.

The light guide plate 130 is disposed above the light sources 110, and a plurality of inclined grooves 131 are formed on a lower surface of the light guide plate 130 to be spaced apart from each other. The inclined grooves 131 are disposed at positions corresponding to the upper portions of the plurality of light sources, and have an inclined surface 132 that reflects the light emitted from the light sources 110 and guides the light toward the inside. The inclined groove 131 has a cross-sectional shape of a substantially right triangle, and the inclined surface 132 of the inclined groove 131 is incident to the light guide plate 130 to reflect the light from the light source 110. Reflective material is coated. Herein, the reflective material may be any material that can reflect the light. The inclined surface 132 may adjust the reflection direction of the light according to the inclination degree. For example, the inclined surface 132 may be formed to be inclined to reflect the light at 90 degrees, but may be reflected at various angles according to various inclinations.

On the other hand, with reference to Figure 5 with respect to the inclined groove 131 of the light guide plate 130, the inclined groove 131 has an inclined surface 132, as shown, the width W of a certain size ), The length L and the depth D formed in the light guide plate 130. First, the width W of the inclined groove 131 is determined according to the size of the LED 110, the divergence angle of light, and the thickness T of the light guide plate 130, and is generally within a range of about 0.5 mm to 5 mm. It is decided. Here, the inclined groove 131 becomes deeper as the width (W) becomes wider, so that the light guide plate 130 also becomes thicker. Therefore, in the case of a slim backlight unit, the width W and the depth D are preferably determined within about 2 mm. The length L of the inclined groove 131 may be disposed as long as the width of the light guide plate 130, or in the case of the circular light guide plate 130, may be arranged as long as the circumference.

Here, the light guide plate 130 may have a rectangular shape or a circular shape when viewed in a plan view (see FIGS. 10, 11, 12, and 13), and may have various shapes by forming a straight or curved shape in a longitudinal cross section. You can do

The optical splitters 140, 210, 340, 142, and 144 are disposed on the upper or lower surface or the upper and lower sides of the light guide plate 130, and the light traveling through the inside of the light guide plate 130 may be selected by one or more selected from total internal reflection, refraction, and scattering. It serves to guide the outside of the light guide plate 130.

The optical splitters 140, 210, 340, 142, and 144 may be optical splitters 140 disposed on an upper side of the light guide plate 130, micro lens arrays 210, or scattering units 340 disposed below the light guide plate 130. It can be applied in various ways.

Hereinafter, the optical splitter will be described in detail.

6 to 9, the optical splitter body is disposed on the upper surface of the light guide plate 130 in plural numbers, and the light traveling through the inside of the light guide plate 130 is totally internally reflected by the liquid crystal panel 160. ) Includes an optical branch unit 140 branching to an upper side of the light guide plate 130. Here, the optical branch 140 may be integrally formed with the light guide plate 130.

The optical branch 140 may be formed in a reverse circular truncated cone shape of FIGS. 6 and 7, or a reverse prism shape of left and right symmetry types in FIGS. 8 and 9, but other cylinders Of course, it may be formed of any one selected from the shape, the square pillar shape, hemi sphere shape, binary diffraction grating and sinusoidal grating. In addition, the optical branch unit 140 may include a plurality of scattering beads (not shown) therein.

On the other hand, in the case of an inverted cone shape or an inverted prism shape, the optical branch unit 140 may determine an angle θ formed between the side surface of the optical branch unit 140 and the upper surface of the light guide plate 130. It is preferable to set it as the range of 45-75 degree | times. This is to allow branched light to branch vertically from the light guide plate 130. Here, D ₁ represents an upper diameter of the optical branch 140, D ₂ represents a lower diameter, H represents a height, a width of an upper surface of D ₃ , an L represents a length, an E represents a height, and a D ₄ lower surface.

The optical branch unit 140 may be arranged in various shapes such as a checkerboard shape having a predetermined width and width or a hexagonal shape on the upper surface of the light guide plate 130.

The light splitter 140 increases the number, i.e., density, of the light guide plate 130 per unit area as it moves away from the inclined groove 131 or the light source (LED) 110. This is to ensure uniform luminance distribution of light emitted from the entire surface of the light guide plate 130 and uniformity of light emitted to the liquid crystal panel 160. That is, the reason is that the LED 110 light is strong in the area close to the light source 110 and the inclined groove 131, and is diffused and weak in the far area. Since the intensity should be equal, the density of the light splitting unit 140 per unit area should increase as the distance from the region close to the inclined groove 131 increases. Here, since the light intensity decreases in inverse proportion to the square of the distance from the LED 110, the number of the light splitters 140 should increase in proportion to the square of the distance from the LED 110 on the contrary.

Referring to FIG. 9, the light induction flows in the light guide plate 130 and the optical branch unit 140 will be described. Light emitted from the LED 110 is reflected from the inclined surface 132 of the light guide plate 130 and is incident into the light guide plate 130, and the light incident into the light guide plate 130 is totally internally reflected by the light guide plate 130. Will proceed inside. The light traveling in the light guide plate 130 is incident into the light splitter 140 disposed on the upper surface of the light guide plate 130, and the light incident into the light splitter 140 is again inside the light splitter 140. Branching is vertically upward in the direction of the liquid crystal panel 160 disposed on the light guide plate 130 by total reflection.

On the other hand, the optical splitter may be applied to the micro lens array 210. Referring to FIG. 10, the backlight unit 200 according to the second exemplary embodiment of the present invention is disposed on the upper surface of the light guide plate 130 to be spaced apart from each other, and total internal reflection of light traveling through the light guide plate 130 is performed. It further comprises a micro lens array 210 consisting of a plurality of micro lenses 211 branched to the image by the. The microlens array 210 includes a plurality of hemispherical microlenses 211, and the microlenses 211 are spaced apart from each other on an image side of the light guide plate. The direct type backlight unit 200 including the micro lens array 210 has an advantage of being easier to manufacture than the light splitter 140 although the performance of bending the light in the vertical direction is weak.

Thus, looking at the light induction flow by the micro lens array 210, the light emitted from the LED 110 is reflected from the inclined surface 132 of the inclined groove 131 formed in the light guide plate 130, the light guide plate 130 After entering the light source, the light is incident on the total internal reflection, and exits upward through the microlens 211 disposed on the upper surface of the light guide plate 130. However, the traveling direction of the light emitted at this time tends to be emitted at an angle rather than perpendicular to the upper surface of the light guide plate 130. For this reason, the backlight unit 200 according to the second exemplary embodiment of the present invention may scatter scattering beads (not shown) inside the microlens 211 so that light is diffused and emitted near the vertical direction. The scattering beads are formed of transparent beads of several micrometers in diameter. In addition, the backlight unit 200 may include a diffusion sheet 150 between the light guide plate 130 and the liquid crystal panel in preparation for the case where light scattered by scattering beads scattered inside the microlens 211 is not sufficient. It may be provided, in addition to the optical sheet such as a light collecting sheet, a polarizing reflection sheet can be further widened the direction and the viewing angle of the light.

On the other hand, the direct backlight unit (100,200), the diffusion sheet 150 is disposed between the light guide plate 130 and the liquid crystal panel 160 to adjust the light diffusion angle and to improve the uniformity of the light. Here, the diffusion sheet 150 is to improve the diffusion angle and uniformity of the light, it is of course not necessary to arrange the diffusion sheet 150 in some cases.

11 to 14 are plan views illustrating an arrangement relationship between the inclination grooves 131, 131a, and 131b of the LEDs 110 and 110b and the light guide plates 130, 130a, and 130b. First, referring to FIG. 11, the light guide plate 130 is rectangular in plan view, and the inclined groove 131 is formed in a rectangular shape along the longitudinal direction (width direction) of the light guide plate 130. The inclined grooves 131 are disposed to be spaced apart at regular intervals in the vertical direction, and the plurality of LEDs 110 are spaced apart at regular intervals along the inclined grooves 131.

FIG. 12 is a plan view of the light guide plate 130 including the optical branch unit 140 in FIG. 11, the configuration of which is identical to that of FIG. 11 except for the optical branch unit 140. Let's do it. On the other hand, the light splitter 140 is arranged to be spaced apart from each other at the same interval on the drawing, but the distance per unit area, that is, the density per unit area may increase as the distance away from the inclined groove 131 and the light source 110. Of course.

This optical principle works the same when the light guide plates 130a and 130b of FIGS. 13 and 14 are circular. Referring to FIG. 13, when the planar shape of the light guide plate 130a is circular, the arrangement shape and structure of the inclined groove 131a and the LED 110 correspond to the shape of the light guide plate 130a. The slanted grooves 131a are arranged in a band shape, and a plurality of the inclined grooves 131a are spaced apart from the edge of the circular light guide plate 130a in a concentric manner at a predetermined interval along the circumferential direction. Here, the LED 110 is disposed in a plurality at regular intervals along the inclined groove 131a of the circular band shape. As described above, in the case where the shape of the light guide plate 130a is circular, the utilization thereof may be increased, and the light guide plate 130a may be applied not only to the backlight of the LCD but also to circular illumination.

FIG. 14 is a plan view showing another embodiment of the light guide plate 130b. Referring to the drawings, the light guide plate 130b has a circular planar shape and a hole is formed in the center thereof. The light guide plate 130b may include a plurality of inclined grooves 131b disposed radially at regular intervals with respect to the center portion in a straight line shape, and a light source positioned at a position corresponding to the inclined grooves 131b. 110b). The backlight unit including the light guide plate 130b having the above-described structure may constitute a circular direct-guide light illuminator.

Meanwhile, referring to FIG. 15, the backlight unit according to the present exemplary embodiment is disposed between the inclined groove 131 and the light source 110 so that the light emitted from the light source 100 is totally inclined by the total internal reflection. 132 and a plurality of photoconductors 170 to guide efficiently into the light guide plate 130. The photoconductor 170 is to improve the uniformity and light transmission efficiency by mixing the light emitted from the LED 110, can be a cylindrical or flat plate, the top may be flat or hemispherical.

Thus, looking at the light induction flow by the photoconductor 170, first, the light emitted from the LED 110 in the state in which the photoconductor 170 is disposed above the LED 110, the first The light incident on the light guide 170 and incident on the light guide 170 are mixed and uniform. The light formed in the uniform state inside the photoconductor 170 is collected by the hemispherical portion of the upper surface of the photoconductor 170 and then enters the inclined surface 132 and enters the inclined surface 132. Is reflected to enter the light guide plate 130 more efficiently.

On the other hand, the photoconductor (not shown), as shown in Figure 15 can be in the shape of a plate other than the case where the upper portion is formed in a hemispherical shape. When the photoconductor is in the form of a flat plate, the inclined surface 132 and the LED 110 may be formed in a transparent structure having a long rectangular plate shape, and the upper portion of the photoconductor is integrally formed with a cylindrical lens. It is possible to simultaneously receive the light from the LED (110). Here, the photoconductor may be formed in various applications such as integrally forming the cylindrical lens of the upper portion or, if necessary, separated and then bonded.

16 is a cross-sectional view illustrating a direct type backlight unit 300 according to a third embodiment of the present invention. Referring to the drawings, the direct type backlight unit 300 according to the third embodiment of the present invention may include a light guide plate 330, a plurality of scattering units 340 as optical splitters, a plurality of LEDs 110, And a reflection sheet 360 and a diffusion sheet 350.

Here, the plurality of LEDs 110 and the light guide plate 330 respectively correspond to the LED 110 and the light guide plate 130 of FIG. 3, and thus a detailed description thereof will be omitted.

The scattering units 340 are disposed on a lower surface of the light guide plate 330 to serve to diverge the light traveling through the light guide plate 330 by scattering.

In detail, the scattering unit 340 may be a scattering pattern or a groove (V-groove) formed on the lower surface of the light guide plate 330. Here, the groove is preferably formed in the shape of "V" type, which can of course vary the shape of the U-shaped, such as an embodiment. In addition, the scattering unit 340 may include a plurality of paint dots including beads, a plurality of concave three-dimensional optical structures that may cause light scattering, provided on a lower surface of the light guide plate 330, Any one selected from a microlens array, a cylinder, a square column, a binary diffraction grating, and a sine diffraction grating can be used. However, in one embodiment, the scattering unit 340 may be any one that can achieve the purpose of scattering the light incident into the light guide plate 330 in addition to the above configuration.

The reflective sheet 360 is disposed between the light guide plate 330 and the plurality of LEDs 110 to reflect light emitted from the lower portion of the light guide plate 330 to the upper side and to send the light to the light guide plate 130 again. do.

The diffusion sheet 350 may be formed of one or a plurality of diffusion sheets 351 and 352 and disposed on the light guide plate 330 to vertically propagate the light emitted from the light guide plate 330 in a vertical direction. To secure the required viewing angle.

On the other hand, the third embodiment of the present invention, as a guide to the light emitted from the light guide plate 330, although the diffusion sheet 350 is applied, the optical sheet that can achieve the purpose of the diffusion sheet 350 (E.g., prism sheet).

In the light guided flow of the third embodiment of the present invention, the light emitted from the LED 110 is first reflected from the inclined surface 332 of the inclined groove 331 and enters into the light guide plate 330. The light is scattered by the scattering unit 340 and the light upwards or downwards is partially reflected by the reflective sheet 360 and then travels upwards. Then, the light is moved from the light guide plate 330. It exits to the liquid crystal panel 160. At this time, if the light emitted from the light guide plate 330 proceeds obliquely, the diffusion sheet 350 advances the light in a vertical direction.

Referring to FIG. 17, the backlight unit 300B according to the present exemplary embodiment may include a light guide plate 330, scattering units 340, LEDs 110, a reflective sheet 360, and a light condenser as an optical splitter. Sheet 370. This is a case where a plurality of light collecting sheets 371 and 372 are applied instead of the diffusion sheet 150 as compared with the backlight unit 300 of FIG. 16, and other components except for the light collecting sheet 370 are substantially the same as those of FIG. 16. same.

The light collecting sheet 370 may be configured by arranging one or a plurality of light collecting sheets 371 and 372, and serves to guide light emitted from the light guide plate 330 to the liquid crystal panel 160. The light collecting sheet 370 may be applied as a prism sheet or a micro lens array. However, the light collecting sheet 370 may have various embodiments in addition to the prism sheet and the micro lens array as long as the light collecting sheet 370 may achieve the purpose of the light collecting sheet 370.

 Here, the light collecting sheet 370 is substantially the same as a known light collecting sheet, so a detailed description thereof will be omitted. In addition, the micro lens array corresponds to the technical configuration of the micro lens array 210 of the first embodiment of the present invention. Detailed description thereof will be omitted. Meanwhile, in addition to the above configuration, both the diffusion sheet 350 and the light collecting sheet 370 may be disposed between the light guide plate 330 and the liquid crystal panel 160.

FIG. 18 is a cross-sectional view illustrating a direct light guide type backlight unit according to a fourth exemplary embodiment of the present invention. FIG. Referring to the drawings, the direct-light guide type backlight unit 400 according to the fourth embodiment of the present invention includes a light guide plate 130 having a plurality of light sources 111, a plurality of inclined grooves 131, and a light powder. The substrate 142 and 144, the reflective sheet 180, and the diffusion sheet 150 are included. The direct light guide backlight unit 400 may be utilized in a planar lighting device. Here, since the light sources 111, the light guide plate 130, and the diffusion sheet 150 are substantially the same as those of FIG. 3, a detailed description thereof will be omitted, and only portions that are distinguished from them will be mainly focused. Let's look at it.

The optical splitters 142 and 144 may include a plurality of square pillar-shaped optical splitters 142 provided on an upper surface of the light guide plate 130, and a plurality of light scattering patterns 144 formed on a lower surface of the light guide plate 130. .

The light scattering pattern 144 serves to guide light incident to the inside of the light guide plate 130 to travel toward the liquid crystal panel 160 by scattering, and the grooves V in addition to the light scattering pattern 144. -groove) or microlens array can be used.

Here, the direct light guide type backlight unit 400 according to the fourth embodiment includes the light diverter 142 and the light guide plate 130 provided on the light guide plate 130. In this case, the light scattering pattern 144 is formed on the lower surface of the lower surface of the light scattering pattern 144. Alternatively, the light scattering pattern 144 formed on the lower surface of the light scattering pattern 144 may be formed. Of course.

The reflective sheet 180 is provided below the light guide plate 130 to serve to reflect light descending below the light guide plate 130 upward.

19 is a cross-sectional view of a direct-lighting type backlight unit according to a fifth embodiment of the present invention. Referring to the drawings, the backlight unit 500 according to the fifth embodiment of the present invention includes the light source 110b and the light source 110b to improve the uniformity of the light by removing the bright spots by mixing the light, as compared with FIG. 19. It further comprises a light mixing light guide plate 700 for coupling.

The light mixing light guide plate 700 is coupled to the side surface of the light source 110b and enters the light from the light source therein, and diffuses or mixes the light to the inclined groove 131 of the light guide plate 130. It serves to enter. The light mixing light guide plate 700 is coupled to the light source 110b at one end thereof, and a reflecting surface 720 for reflecting light from the light source 110b at the other end to guide the inclined groove 131. Formed. Since the reflective surface 720 is formed to be inclined, the light inside the light mixing light guide plate 700 may efficiently transmit light to the light guide plate 130 positioned above. Here, the plurality of light sources 110b are arranged in plurality in a straight line on the incident surface of the light mixing light guide plate 700.

In detail, the light mixed light guide plate 700 first enters light from the light source LED corresponding to a point light source into the light mixed light guide plate 700 to diffuse or / and mix, and then enters a light source incident surface. The opposite side of the light guide plate 130 is inclined toward the inclined groove 131 of the light guide plate 130 to be incident into the light guide plate 130. In this case, the reflective surface 720 may adjust the inclination angle between 10 degrees and 70 degrees to allow most of the light to enter the upper light guide plate 130. Similarly, the reflective surface 720 is coated with a reflective material which reflects the light emitted from the light source and enters the light guide plate 130 to prevent the light from leaking.

20 is a perspective view showing the structure of the light mixing light guide plate 700 described above. Referring to the drawings, the light mixing light guide plate 700 is reflected by the reflecting surface 720 after the light from the light sources arranged spaced along one side is mixed while being incident and diffused in the longitudinal direction to the inside As a result, the direction of the light guide plate 130 is changed to the upward direction to be incident into the inclined groove 131 of the light guide plate 130. In this case, the inclination θ of the reflective surface 720 may be variously designed within the inclination range described above, and preferably, the inclination θ of the reflective surface 720 is in the range of 10 to 70 degrees. Thus, in the present embodiment, the light emitted from the light source is diffused and mixed by the light mixing light guide plate 700 to form uniform light, which is incident on the light guide plate 130 on the upper side, thereby eliminating bright spots, thereby providing even more uniform light. You can get it. Here, the light mixing light guide plate 700 is applicable to the backlight units according to the first to fourth embodiments in addition to the direct light guide type backlight unit according to the fifth embodiment.

FIG. 21 is a diagram illustrating a sixth embodiment of the present invention. Referring to the drawings, the direct type backlight unit 600 according to the sixth embodiment of the present invention is compared with the fifth embodiment of FIG. An optical waveguide 800 is included instead of the light mixing light guide plate 700, and the light emitted from the light source 110c which is a point light source through the linear optical waveguide 800 is converted into a linear light source. It is a structure to change.

22 and 23 are perspective views illustrating various embodiments of the optical waveguide 800 and the optical waveguide 800. First, referring to FIG. 22, the optical waveguide 800 includes a plurality of first optical branch structures 910 arranged to be spaced apart from each other. The first optical splitter structure 910 guides upward when light emitted from the light source 110c travels along the optical waveguide 700 to form a linear light source. Meanwhile, in the present embodiment, the first optical branch structure 910 has a cylindrical shape, but in addition, the first optical branch structure 910 has a reverse circular truncated cone shape and an inverted prism ( reverse prism) shape, square pillar shape, hemi sphere shape, binary diffraction grating and sinusoidal diffraction grating may be any one of the selected shape.

Referring to FIG. 23, the optical waveguide 800 is formed on a lower surface of the optical waveguide 800 when light emitted from the light source 110c travels along the light guide path 700, and is formed along the optical waveguide 800. It includes a plurality of scattering patterns 920 to guide the advancing light to form a linear light source. In the present embodiment, a case in which a plurality of scattering patterns 920 are formed on the bottom surface of the optical waveguide 800 is illustrated as an example. In addition to the scattering pattern 920, a plurality of grooves (V-grooves) and a plurality of microlenses are used. An array, a binary diffraction grating, a sinusoidal diffraction grating, or the like may be installed to guide light inside the optical waveguide 800 to the upper or lower portion of the optical waveguide 800.

In this case, the optical waveguide 800, when the scattering pattern 920 is provided on the lower surface of the optical waveguide 800, the upper surface of the optical waveguide 800 is further provided with a cylindrical lens or the like, the light transmission efficiency Can improve. In addition, the optical waveguide 800 includes a reflective member 930 at a lower portion of the optical waveguide 800 so as to guide the light guided downward from the optical waveguide 800 upward.

Meanwhile, in the present exemplary embodiment, one light source unit including a plurality of light sources 110 arranged in one row and an area from one inclined groove 131 to a boundary line from the adjacent light source unit and the inclined groove are one Compartments. Thus, in the present embodiment, by providing a plurality of the above-described partitions can be configured a large-area direct-guided planar lighting device, the partitions can be a unit of regional driving. Here, like numerals denote substantially identical configurations.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100,200,300,300B, 400,500,600 ... Backlight Unit
110 ... light source (LED) 120 ... backplane
130,130a, 130b ... Light guide plate 131,331 ... Inclined groove
132,332 ... slope 140,140b ... optical branch
150,350,420 ... optical sheet 160 ... LCD panel
210 ... Micro Lens Array 211 ... Micro Lens
340 ... scattering part 360 ... reflective sheet
370 ... light collecting sheet 700 ... light mixing light guide plate
800 ... optical waveguide

Claims (21)

A plurality of light sources;
A light guide plate disposed on an upper side of the light sources, the light guide plate having a plurality of inclined grooves formed on a lower surface of the light source and having an inclined surface for reflecting light emitted from the light source and proceeding inwardly; And
Is disposed on at least one of the upper surface and the lower surface of the light guide plate, and includes a plurality of optical splitter guides the light traveling through the light guide plate to the outside of the light guide plate by any one or a plurality selected from total internal reflection, refraction and scattering and,
The inclined surface of the light guide plate, the direct type backlight unit is coated with a reflective material for reflecting the light from the light source to enter the light guide plate. A plurality of light sources;
A light guide plate disposed on an upper side of the light sources, the light guide plate having a plurality of inclined grooves formed on a lower surface of the light source and having an inclined surface for reflecting light emitted from the light source and proceeding inwardly; And
A plurality of light splitters disposed on at least one of an upper surface and a lower surface of the light guide plate and configured to guide the light traveling through the light guide plate to the outside of the light guide plate by any one or a plurality of internal reflection, refraction, and scattering; And
And a light mixing light guide plate coupled to a side surface of the light source to allow light from the light source to enter the light source, and to diffuse or mix the light and then enter the inclined groove of the light guide plate. The method according to claim 1 or 2,
The light source is
And a direct type backlight unit positioned at a portion corresponding to a lower portion of the light guide plate with respect to a vertical direction of the inclined groove. The method according to claim 3,
The light source is a direct type backlight unit of a white light LED or R, G, B LED. The method according to claim 1 or 2,
The light guide plate is a direct type backlight unit having a planar quadrangular or circular shape. The method according to claim 1 or 2,
The optical splitter,
It is disposed on the upper surface of the light guide plate to branch the light traveling through the light guide plate to the upper side by total internal reflection,
An optical branch formed of any one selected from a reverse circular truncated cone shape, a cylindrical shape, a square column shape, a reverse prism shape, a hemisphere shape, a binary diffraction grating, and a sinusoidal diffraction grating Direct type backlight unit including. The method of claim 6,
The optical branch unit,
The direct backlight unit having an inverted cone shape or an inverted prism shape, wherein an angle formed between a side surface and an upper surface of the light guide plate is in a range of 45 degrees to 75 degrees. The method of claim 6,
The optical branch unit,
The direct type backlight unit further includes a plurality of scattering beads therein. The method according to claim 1 or 2,
The optical splitter,
And a plurality of micro lens arrays arranged on the upper surface of the light guide plate to be spaced apart from each other to split light traveling through the inside of the light guide plate toward the upper side by total internal reflection. The method according to claim 1 or 2,
The optical splitter,
A plurality of direct-type backlight unit is disposed on the lower surface of the light guide plate including a scattering unit for splitting the light traveling through the light guide plate by scattering. The method of claim 10,
The scattering unit,
A plurality of paint dots including beads, microlens arrays, cylinders, square columns, binary diffraction gratings, sinusoidal diffraction gratings, scattering patterns and grooves formed on the bottom surface of the light guide plate are provided on the bottom surface of the light guide plate. Direct type backlight unit is any one selected from. The method according to claim 1 or 2,
The direct backlight unit is disposed between the inclined groove and the light source, and further includes a plurality of light guides to guide light from the light source into the light guide plate. The method of claim 12,
The photoconductor is a direct type backlight unit having a cylindrical shape or a flat plate shape. The method according to claim 13,
The upper portion of the light guide is a direct type backlight unit having a flat or hemispherical shape. The method according to claim 1 or 2,
The optical splitters,
The direct type backlight unit increases the number per unit area as it moves away from the light source. The method according to claim 15,
The optical splitter is a direct type backlight unit integrally formed with the light guide plate. The method according to claim 1 or 2,
And a reflective sheet disposed between the light guide plate and the plurality of light sources. 18. The method of claim 17,
A liquid crystal panel is disposed on the light guide plate,
And a diffusion sheet or a light collecting sheet between the light guide plate and the liquid crystal panel. 19. The method of claim 18,
The light collecting sheet,
Direct backlight unit which is prism sheet or micro lens array. delete The method according to claim 2,
The light mixing light guide plate,
A direct type backlight unit having an inclined reflective surface coupled to one end of the light source and reflecting light from the light source to the other end to the inclined groove.

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