KR20030078529A - Backlight unit - Google Patents

Abstract

The present invention relates to a backlight unit having a direct sequential backlight by converting a light source in the form of a point light source into a form of a linear light source, and having a field sequential backlight capable of segmented driving by region by adjusting the color of the point light source.

The backlight unit according to the present invention includes a plurality of light emitting diodes for generating light, a plurality of linear light guide plates arranged side by side so as to correspond to the plurality of light emitting diodes, respectively, and converting point light sources from the light emitting diodes into linear light sources; And a diffuser plate formed to cover the entire surface of the linear light guide plate to diffuse light through the plurality of linear light guide plates so as to have a uniform light distribution on the effective light emitting surface of the flat panel display panel.

By such a configuration, the backlight unit according to the present invention can configure a direct type backlight unit by converting an LED into a linear light source by arranging LEDs on one or both sides of the linear light guide plate. In addition, by selectively emitting LEDs based on a plurality of linear light guide plates, it may be used as a field sequential light source that emits divided light for each region or only a specific region.

Description

Backlight Unit

The present invention relates to a backlight unit, and in particular, a backlight having a direct sequential backlight by converting a light source in the form of a point light source into a linear light source and having a field sequential backlight capable of segmented driving by region by adjusting the color of the point light source. It's about the unit.

Typically, a liquid crystal display (hereinafter referred to as "LCD") is a plurality of liquid crystal cells arranged in a matrix form and a plurality of control switches for switching the video signal to be supplied to each of these liquid crystal cells The amount of light transmitted from the backlight unit is adjusted by the configured liquid crystal panel to display a desired image on the screen.

1 and 2, a conventional backlight unit includes a lamp 1 for generating light, a lamp housing 3 installed in a form surrounding the lamp 1, and light incident from the lamp 1. The light guide plate 5 converting into a planar light source, a reflecting plate 7 positioned below the light guide plate 5 to reflect the light traveling toward the lower surface and the side surface of the light guide plate 5 toward the upper surface, and through the light guide plate 5. First diffusion sheet 9 for diffusing light, first and second prism sheets 11 and 13 for adjusting a traveling direction of light via the first diffusion sheet 9, and prism sheets 11 and 13 And a second diffusion sheet 15 for diffusing the light via the light source.

Cold Cathode Fluorescent Lamp (hereinafter referred to as “CCFL”) is mainly used as the lamp 1, and the light generated from the lamp 1 is transmitted through an incident surface existing on the side of the light guide plate 5. Incident on the light guide plate 5. The lamp housing 3 has a reflecting surface on its inner surface to reflect light from the lamp 1 toward the incident surface of the light guide plate 5. The light guide plate 5 is manufactured in a form having an inclined rear surface and a horizontal front surface. The rear side of the light guide plate 5 is provided so that the reflecting plate 7 faces. The reflector 7 serves to reduce light loss by reflecting light incident to itself through the back of the light guide plate 5 toward the light guide plate 5. When light from the lamp 1 is incident on the light guide plate 5, the light is reflected at a predetermined inclination angle from the inclined rear surface and proceeds uniformly toward the front surface. At this time, the light propagated toward the lower surface and the side surface of the light guide plate 5 is reflected by the reflecting plate 7 and proceeds toward the front side. Light passing through the light guide plate 5 is diffused to the entire area by the first diffusion sheet 9. On the other hand, the light incident on the liquid crystal panel (not shown) increases the light efficiency when it is vertical. To this end, it is preferable to stack two forward prism sheets so that the traveling angle of the light emitted from the light guide plate 5 is perpendicular to the liquid crystal panel. Light passing through the first and second prism sheets 11 and 13 is incident on the liquid crystal panel via the second diffusion sheet 15.

Such backlight units are in the trend of miniaturization, thinning, and weight reduction. According to this trend, light emitting diodes (hereinafter referred to as "LEDs"), which are advantageous in power consumption, weight, and luminance, have been proposed instead of the CCFL used in the backlight unit.

Referring to FIG. 3, a direct backlight unit includes a plurality of LEDs 21 for generating light, a support 23 for supporting the LEDs 21, and a light diffused from the plurality of LEDs 21. It consists of a diffuser plate 25.

The LED 21 generates red light, green light and blue light as point light sources. The support 23 supports a plurality of LEDs 21 and has a reflective surface for advancing the light generated from the LEDs 21 to the front side. The diffusion plate 25 is disposed with the LED 21 and a predetermined interval therebetween so that the light from the LED 21 has a uniform distribution.

Figure 4 is a perspective view showing the configuration of another backlight unit according to the prior art.

Referring to FIG. 4, another backlight unit according to the related art includes one LED 31 generating light, a pre-light guide 33 installed to surround the LED 31, and A light guide plate 35 for converting light incident from the LED 31 into a planar light source, and a reflector plate (not shown) for reflecting light which is located below the light guide plate 35 and propagates toward the bottom and side surfaces of the light guide plate 35. And a diffusion sheet (not shown) for diffusing the light via the light guide plate 35.

The LED 31 generates red light, green light and blue light, and causes each light to travel toward the free light guide 33. The free light guide 33 converts the point light source from the LED 31 into a linear light source and guides the light guide plate 35 toward the light guide plate 35. The free light guide 33 has a triangular shape. A groove 33A is formed at a vertex of this triangle so that one LED 31 can be located in a size corresponding to the LED 31. The free light guide 33 has an inclined surface 33B in the form of a triangle. The angle θ between the inclined surface 33B and the LED 31 is formed between 45 ° and 89 °. Here, the optimum angle of light incidence is best is 45 °, but when the inclined surface of the pre-light guide 33 is produced at 45 ° the size of the free light guide 33 is increased, it is suitable between 45 ° to 89 ° Made at an angle. Here, since the refractive index of the material forming the free light guide 33 is much larger than the refractive index of air, the light from the LED 31 is totally reflected at the inclined surface of the free light guide 33 to be incident on the side of the light guide plate 35. It enters into the light guide plate 35 through the surface.

The light guide plate 35 is manufactured to have a sloped rear surface and a horizontal front surface. The rear surface of the light guide plate 35 is provided so that the reflecting plate faces. The reflector serves to reduce light loss by rereflecting light incident to the light through the rear surface of the light guide plate 35 toward the light guide plate 35. When light from the lamp 31 is incident on the light guide plate 35, the light is reflected at a predetermined inclination angle from the rear surface, which is an inclined surface, to uniformly move toward the front surface. At this time, the light propagated toward the lower surface and the side surface of the light guide plate 35 is reflected by the reflecting plate and proceeds toward the front side. Light passing through the light guide plate 35 is diffused by the diffusion sheet and is incident on the liquid crystal panel (not shown).

5 is a perspective view showing the configuration of another backlight unit according to the prior art.

Referring to FIG. 5, another backlight unit according to the related art includes a plurality of LEDs 41 for generating light, an LED module 43 for arranging a plurality of LEDs 41 in a constant column direction, and a plurality of LEDs. A light guide plate 45 for converting light incident from the LED 31 into a planar light source is provided. In addition, a LED module including a LED 41 may be provided below the light guide plate 45 to reflect the light traveling toward the lower surface and the side surface of the light guide plate 5 toward the upper surface. May be formed on both sides as well as on one side.

The LED 41 generates red light, green light and blue light, and causes each light to travel toward the light guide plate 45. The light guide plate 45 is manufactured to have a sloped rear surface and a horizontal front surface. The rear surface of the light guide plate 45 is provided so that the reflecting plate faces. The reflector serves to reduce light loss by rereflecting light incident to the light through the rear surface of the light guide plate 35 toward the light guide plate 35. When the light from the LED 41 is incident on the light guide plate 45, the light is reflected at a predetermined inclination angle from the rear surface which is an inclined surface and uniformly travels toward the front surface. At this time, the light propagated toward the lower surface and the side surface of the light guide plate 45 is reflected by the reflecting plate and proceeds toward the front side. Light passing through the light guide plate 45 is diffused by the diffusion sheet and is incident on the liquid crystal panel (not shown).

However, when a plurality of LEDs are arranged in the backlight unit according to the related art as described above, there is a problem of increased power consumption on a large screen. In addition, a backlight unit using a light guide plate having a panel size has disadvantages of uneven brightness and low brightness.

Accordingly, an object of the present invention is to provide a backlight unit configured to configure a direct type backlight by arranging LEDs having a point light source form a plurality of linear light guide plates side by side.

Another object of the present invention is to provide a backlight unit to implement a field sequential backlight capable of segmented driving by region by adjusting the color of a point light source type LED formed on one side or both sides of a plurality of linear light guide plates.

1 is a perspective view showing the configuration of a backlight unit according to the prior art.

FIG. 2 is a cross-sectional view of the backlight unit shown in FIG. 1. FIG.

Figure 3 is a perspective view showing the configuration of another backlight unit according to the prior art.

Figure 4 is a perspective view showing the configuration of another backlight unit according to the prior art.

Figure 5 is a perspective view showing the configuration of another backlight unit according to the prior art.

6 is a perspective view of a backlight unit according to a first embodiment of the present invention;

7 is a view for explaining that the point light source according to the present invention is changed to a direct light source by the linear light guide plate.

8 is a perspective view of a backlight unit according to a second embodiment of the present invention;

9 is a cross-sectional view showing a light incident surface of a linear light guide plate according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

1 lamp 3 lamp housing

5,35,45: Light guide plate 15,55: Diffusion sheet

11,13: Prism sheet 21,31,41,51: LED

23: support 25: diffusion plate

33: free light guide 53: linear light guide plate

57: optical pattern

In order to achieve the above object, the backlight unit according to the present invention is arranged side by side so as to correspond to each of the plurality of light emitting diodes for generating light and the plurality of light emitting diodes to convert the point light source from the light emitting diodes into linear light sources. A plurality of linear light guide plates, and a plurality of linear light guide plates formed to cover the entire surface of the plurality of linear light guide plates so as to spread light through the plurality of linear light guide plates so as to have a uniform light distribution on the effective light emitting surface of the flat panel display panel. It is characterized by including a plate.

The linear light guide plate of the present invention is characterized by having an optical pattern on the inner lower surface to evenly radiate the light supplied from the light emitting diode to the upper surface.

In the present invention, it is characterized in that it further comprises a reflector for causing the light from the linear light guide plate to advance toward the front.

A plurality of light emitting diodes according to the present invention is characterized in that the selective light emission for each area corresponding to the plurality of linear light guide plate.

The linear light guide plate of the present invention is characterized by having a light incident surface of any one of circular, semicircular and arbitrary polygons.

Other objects and features of the present invention other than the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

6 to 9 will be described a preferred embodiment of the present invention.

FIG. 6 is a perspective view illustrating a backlight unit according to a first embodiment of the present invention, and FIG. 7 is a view for explaining that a point light source according to the present invention is changed into a light source having a direct shape by a linear light guide plate.

6 and 7, a backlight unit according to a first embodiment of the present invention includes a plurality of LEDs 51 generating light and a plurality of LEDs arranged side by side in a direction in which light of the LEDs 51 shines. A linear light guide plate 53 and a diffuser plate 55 for diffusing light from the plurality of linear light guide plates 53 are provided. In addition, the lower surface of the linear light guide plate 53 is provided with an optical pattern 57 to evenly radiate the light supplied from the LED 51.

A plurality of LEDs 51 are formed on one side of the plurality of linear light guide plates 53 and generate red light, green light, and blue light as point light sources.

The linear light guide plate 53 is arranged side by side to correspond to one LED 51 to convert the light incident from the LED 51 into a linear light source. The plurality of linear light guide plates 53 are formed to have a front surface that is horizontal with an inclined back surface or are formed to have a front surface that is horizontal with a back surface having a predetermined optical pattern 57. A rear side of the plurality of linear light guide plates 53 may be installed to face a reflecting plate (not shown). In this case, the reflecting plate may be configured in plural to correspond to one linear light guide plate 53 or in one to include a plurality of linear light guide plates 53 in front. The reflector serves to reduce light loss by reflecting light incident to itself through the rear surface of the linear light guide plate 53 toward the linear light guide plate 53. Accordingly, when the light from the LED 51 is incident on the linear light guide plate 53, the light is reflected at a predetermined inclination angle on the inclined rear surface or at a predetermined inclination angle by the optical pattern 57 of a predetermined shape as shown in FIG. It will proceed uniformly. At this time, the light propagated toward the lower surface and the side surface of the light guide plate 53 is reflected by the reflecting plate and proceeds to the front side. In addition, the number of linear light guide plates 53 can be adjusted as necessary, and the selective light emission of the LED 51 enables region division or selective light emission of the flat panel display surface to be used as a field-sequence light source.

The diffuser plate 55 is disposed with the linear light guide plate 53 and a predetermined interval therebetween so that the light from the linear light guide plate 53 has a uniform distribution so as to diffuse the light via the linear light guide plate 53.

FIG. 8 is a perspective view illustrating a backlight unit according to a second exemplary embodiment of the present invention, and unlike the first exemplary embodiment, a plurality of LEDs are arranged on both sides of the linear light guide plate.

Referring to FIG. 8 in conjunction with FIG. 7, a backlight unit according to a second exemplary embodiment of the present invention may include a plurality of LEDs 51a and 51b generating light and a direction in which light of the LEDs 51a and 51b shines. A plurality of linear light guide plates 53 arranged side by side and a diffuser plate 55 for diffusing light traveling from the plurality of linear light guide plates 53 are provided. In addition, the lower surface of the linear light guide plate 53 is provided with an optical pattern 57 to evenly emit light supplied from the plurality of LEDs (51a, 51b).

The plurality of LEDs 51a and 51b are formed at both sides of the plurality of linear light guide plates 53 and generate red light, green light and blue light as point light sources.

The linear light guide plate 53 is arranged side by side so as to correspond to the LEDs 51a and 51b corresponding to both sides, and converts the light incident from the LEDs 51a and 51b into linear light sources. The plurality of linear light guide plates 53 are formed to have a front surface that is horizontal with a rear surface having a predetermined optical pattern 57. A rear side of the plurality of linear light guide plates 53 may be installed to face a reflecting plate (not shown). In this case, the reflecting plate may be configured in plural to correspond to one linear light guide plate 53 or in one to include a plurality of linear light guide plates 53 in front. The reflector serves to reduce light loss by reflecting light incident to itself through the rear surface of the linear light guide plate 53 toward the linear light guide plate 53. As a result, when the light from the LEDs 51a and 51b arranged on both sides is incident on the linear light guide plate 53, the light is reflected at a predetermined inclination angle by the optical pattern 57 of a predetermined shape and uniformly travels in the front direction. At this time, the light propagated toward the lower surface and the side surface of the light guide plate 53 is reflected by the reflecting plate and proceeds to the front side. In addition, the number of linear light guide plates 53 can be adjusted as necessary, and the selective light emission of the LED 51 enables region division or selective light emission of the flat panel display surface to be used as a field-sequence light source.

The diffuser plate 55 is disposed with the linear light guide plate 53 and a predetermined interval therebetween so that the light from the linear light guide plate 53 has a uniform distribution so as to diffuse the light via the linear light guide plate 53.

9 is a cross-sectional view illustrating a light incident surface of a linear light guide plate according to an exemplary embodiment of the present invention. The linear light guide plate 53 is configured in various forms and has an optical pattern accordingly. Various forms of the linear light guide plate 53 may be known through the light incident surface of the linear light guide plate 53.

Referring to FIG. 9, the linear light guide plate 53 according to the present invention has a cross section of a light incident surface composed of any one of a polygon, a circle, and a semicircle. For example, the cross section of the light incident surface may have a circular shape shown in 9 (a), a semicircle shown in FIG. 9 (b), an inverted triangle shown in FIG. 9 (c), and a square shape shown in FIG. 9 (d). Have Accordingly, the linear light guide plate 53 is configured in the form of a triangular prism, a cylinder, a square pillar, or the like based on the light incident surface as described above.

As described above, the backlight unit according to the present invention may configure a direct backlight unit by converting an LED into a linear light source by arranging LEDs on one or both sides of the linear light guide plate. In addition, by selectively emitting LEDs based on a plurality of linear light guide plates, it may be used as a field sequential light source that emits divided light for each region or only a specific region.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (7)

A plurality of light emitting diodes for generating light, A plurality of linear light guide plates arranged side by side so as to correspond to the plurality of light emitting diodes, respectively, for converting point light sources from the light emitting diodes into linear light sources; And a diffuser plate formed on an upper surface of the plurality of linear light guide plates so as to diffuse light through the plurality of linear light guide plates so as to have a uniform light distribution on the effective light emitting surface of the flat panel display panel. Backlight unit. The method of claim 1, And the linear light guide plate has an optical pattern on the inner lower surface to evenly radiate the light supplied from the light emitting diode to the upper surface. The method of claim 1, And a reflecting plate for allowing light from the linear light guide plate to travel toward the front side. The method of claim 1, And the plurality of light emitting diodes selectively emits light corresponding to regions of the plurality of linear light guide plates. The method of claim 1, The linear light guide plate has a light incident surface of any one of a circle, a semicircle, and an arbitrary polygon. The method of claim 5, The arbitrary polygonal unit is a backlight unit, characterized in that consisting of a triangle, a square, a rectangle. The method of claim 5, The linear light guide plate is a backlight unit, characterized in that configured in the form of a cylinder, a semi-cylindrical cylinder and a polygonal cylinder based on the light incident surface.