KR20080081509A - Plane light source using white led and lcd backlight unit comprising the same - Google Patents

Abstract

A surface light source using a white LED(light emitting diode) is provided to reduce limitations on the arrangement of an LED and simplify the structure of a circuit by using only a white LED. A plurality of white LED's(110) are separated from each other by a predetermined interval. The arrangement of the white LED's is adjusted in a manner that the light quantity of an LED unit(U) composed of each white LED and arbitrary LED's disposed at a shortest distance from each white LED becomes 80-120 percent of the average of the total sum of the light emitted from each white LED. The LED unit can have one shape selected from a group of a polygon, a circle or a composition thereof.

Description

Plane light source using white LED and LCD backlight unit having same {Plane light source using white LED and LCD backlight unit comprising the same}

1 and 2 illustrate red (R), green (G) and blue (B) LED arrangements of conventional surface light sources.

3 and 4 show the arrangement of the white (W) LED of the surface light source according to the present invention.

5 is an exploded side view showing an LCD backlight unit having a surface light source using a white LED according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100: surface light source 110: white LED

U: LED unit C: center of LED unit

D ₁ : row spacing D ₂ : column spacing

θ: placement angle 200: LCD backlight unit

210: substrate 220: reflector

230: side wall 235: slope

240: diffusion sheet 250: light collecting sheet

260: protective sheet 270: LCD panel

The present invention relates to a surface light source using a white LED and an LCD backlight unit having the same, and more particularly, to a surface light source capable of obtaining a uniform white light using a white LED and an LCD backlight unit having the same. .

Cold Cathode Fluorescent Lamp (CCFL), which is used as a light source of backlight of conventional LCD, uses mercury gas, which can cause environmental pollution, slow response speed, low color reproducibility, and It has disadvantages that are not suitable for shortening.

In comparison, LEDs are environmentally friendly, respond to high speeds at several nanoseconds, and are effective for video signal streams, enabling impulsive driving, over 100% color reproducibility, and the amount of light from red, green, and blue LEDs. In addition, the brightness, color temperature, and the like can be arbitrarily changed, and the light and small size of the LCD panel can be arbitrarily changed.

As such, LCD backlights employing LEDs can be classified into edge type backlights and direct type backlights, depending on the location of the light source. Edge type backlight has a long bar-shaped light source located on the side and uses light guide plate to irradiate light to the front of LCD panel, and direct type is located at the bottom of LCD panel and is almost same as LCD panel. It adopts a method of irradiating light directly from the surface light source having an area to the front of the LCD panel.

1 and 2 illustrate a red (R), green (G) and blue (B) LED arrangement of a conventional surface light source.

The surface light source 10 used in the conventional direct type LCD panel is a mixture of red (R), green (G) and blue (B) light to generate white light, as shown in FIG. The green and blue LEDs 11, 12 and 13 are arranged in a plurality of quadrangular LED units U arranged in close proximity to the apex of a triangle, or as shown in FIG. 2, the LED units U as described above are replaced. It consists of several triangular arrangements.

However, when the LED units U are arranged in a square as shown in FIG. 1, when the red LED 11 is crowded and viewed on the display, a red line is visible.

And, in the triangular arrangement as shown in Figure 2, relatively red, green and blue are arranged evenly, each of the red, green and blue LED (11, 12, 13) light source is in the original LED unit (U) Since they are tailored to emit white light, in order to match the level with the other two light sources of the surrounding LED unit U, the balance between each LED unit U must also be balanced, so that each light source must be balanced with each other in the overall backlight unit. Should be. This makes the production of the product impossible or deteriorates the quality of the product.

Therefore, in the conventional surface light source 10 and the LCD backlight unit employing the same, there is a problem that there is a limitation in color mixing so that a uniform distribution of white light cannot be obtained.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide a surface light source that can obtain a uniform white light as a whole using a white LED and an LCD backlight unit having the same.

The surface light source using a white LED according to the present invention for achieving the above object is arranged by a plurality of white LEDs spaced at a predetermined interval, consisting of a combination of each white LED and any white LED disposed at the shortest distance therefrom. The arrangement of the white LEDs is adjusted such that the central light amount of the LED unit is 80% to 120% of the average value of the total amount of light emitted from each white LED.

Here, the arrangement adjustment of the white LED is characterized in that for adjusting the row spacing, column spacing and the arrangement angle between the white LED.

In addition, the LED unit is characterized in that it has any one shape selected from the group consisting of polygons, circles and combinations thereof.

In addition, the white LED is characterized by comprising a blue LED chip, a red phosphor and a green phosphor.

In addition, the red phosphor is characterized in that the CaAlSiN ₃ : Eu of the nitride (nitride) composition, or (Ca, Sr) S: Eu of the sulfide-based composition.

In addition, the green phosphor is (Sr, Ba) ₂ SiO ₄ : Eu of the silicate-based composition, SrGa ₂ S ₄ : Eu of the sulfide-based composition, and Beta of the nitride-based composition It is characterized in that it is any one selected from the group consisting of -SiAlON.

And, the LCD backlight unit according to the present invention for achieving the above object, the substrate; A reflection plate provided on the substrate; The central light amount of the LED unit which is provided on the reflector, is arranged in a plurality of white LEDs spaced apart by a predetermined distance, and composed of a combination of each white LED and any white LEDs arranged at the shortest distance therefrom, in each white LED A surface light source in which the arrangement of the white LEDs is adjusted to be 80% to 120% of an average value of the total amount of emitted light; A diffusion sheet provided on the surface light source and uniformly diffusing light incident from the surface light source; And a light collecting sheet provided on the diffusion sheet to collect light diffused from the diffusion sheet.

Here, the protective sheet provided on the light collecting sheet is characterized in that it further comprises.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

Surface light source using white LED

First, a surface light source using a white LED according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

3 and 4 are views showing the arrangement of the white (W) LED of the surface light source according to the present invention.

3 and 4, the surface light source 100 using the white LED according to the present invention is arranged with a plurality of white (W) LEDs 110 spaced a predetermined distance apart.

Although not shown in the drawing, the white LED 110 is preferably composed of a blue LED chip, a red phosphor, and a green phosphor. As the red phosphor, it is preferable to use CaAlSiN ₃ : Eu having a nitride composition or (Ca, Sr) S: Eu having a sulfide composition. Further, the green phosphor may include (Sr, Ba) ₂ SiO ₄ : Eu of silicate-based composition, SrGa ₂ S ₄ : Eu or nitride-based composition of sulfide-based composition It is preferable to use Beta-SiAlON.

When white light is implemented using the white LED 110 as described above, since one-chip is used, compared to the white light implementation using the red, green, and blue LEDs 11, 12, 13. The advantages are simple to manufacture and simple configuration of the circuit.

In particular, in the present invention, by adjusting the arrangement of the white LEDs 110, for example, the row spacing D ₁ , the column spacing D ₂ , and the placement angle θ between the white LEDs 110, each white LED ( In the center (C) of the LED unit (U) consisting of a combination of 110 and any white LEDs (110) arranged at the shortest distance therefrom, the center (C) light amount is at each white LED (110). The sum of the emitted light amounts is 80% to 120% of the average value.

Here, the LED unit U may have a triangular shape as shown in FIG. 3, or may have a quadrangular shape as shown in FIG. 4. Accordingly, the center C of the LED unit U may be the center of gravity of the three white LEDs 110 arranged in a triangle (see FIG. 3), or the four white LEDs 110 arranged in a square shape. It may also be the center of gravity (see FIG. 4).

In addition, the shape of the LED unit (U) is not limited to the shape as described above, within the technical scope of the present invention, for example, any one selected from the group consisting of polygons, circles, and combinations thereof, such as triangular or more. It may be modified in various ways, including.

That is, the present invention has an advantage that the arrangement of the LED 110 is much less than that of the surface light source using the red, green, and blue LEDs by using the white LED 110.

In the present invention, as described above, the center C light amount of the LED unit U is set to be 80% to 120% of the average value of the sum of the light amounts emitted from the respective white LEDs 110. Uniform light quantity can be obtained, and stable production and quality can be realized.

Here, when the center (C) light amount of the LED unit (U) is less than 80% of the average value of the total amount of light of each white LED 110, the efficiency of power per each white LED 110 is lowered rather than the temperature Is increased and power consumption is also increased, the uniformity may be lowered, and if it is greater than 120%, the brightness and uniformity may be improved, but the use of the white LED 110 is disadvantageous in terms of price and manufacturing. .

Therefore, in the present invention, the optimum uniformity can be obtained by adjusting the arrangement of the white LEDs 110 so that the center C light quantity in the above-described numerical range is obtained.

LCD backlight unit with surface light source using white LED

The surface light source as described above may be employed in the LCD backlight unit for irradiating the back light of the LCD panel in the LCD.

Hereinafter, an LCD backlight unit having a surface light source using the white LED of the present invention will be described in detail with reference to FIG. 5.

5 is an exploded side view showing an LCD backlight unit having a surface light source using a white LED according to the present invention.

As shown in FIG. 5, the LCD backlight unit 200 according to the present invention disposed on the rear surface of the LCD panel 270 includes a substrate 210, a reflection plate 220 provided on the substrate 210, and It includes a surface light source consisting of a white LED (110). The reflector 220 serves to reflect the light emitted from the white LED 110 upwards.

The surface light source is provided on the reflector plate 220, and the plurality of white LEDs 110 are arranged to be spaced apart by a predetermined distance as described above, and each white LED 110 and an arbitrary white LED disposed at the shortest distance therefrom ( Between the white LEDs 110 so that the central light amount of the LED unit U formed in combination with the 110s is 80% to 120% of an average value of the total amount of light emitted from each white LED 110. Row spacing D ₁ , column spacing D ₂ , and placement angle θ are adjusted.

On the edge of the reflecting plate 220, a sidewall 230 having an inclined surface 235 is formed to surround the white LED 110. At this time, it is preferable that a reflective material is further applied to the inclined surface 235 of the side wall 230 so as to emit light emitted laterally from the white LED 110.

On the surface light source, a diffusion sheet 240 is provided to uniformly diffuse the light incident from the surface light source to prevent the light from being partially concentrated.

The light collecting sheet 250 is provided on the diffusion sheet 240 to collect light diffused from the diffusion sheet 240 in a direction perpendicular to a plane of the LCD panel 270.

Here, on the light collecting sheet 250, a protective sheet 260 for protecting the lower optical structure may be further provided. The protective sheet 260 not only protects the surface of the light collecting sheet 250, but also serves to diffuse light in order to uniformize light distribution.

The LCD panel 270 is installed on the protective sheet 260.

The LCD backlight unit 200 according to the present invention, by providing a uniform white light to the front of the LCD panel as a surface light source using the white LED 110, it is possible to obtain a clearer LCD image.

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 to the disclosed embodiments, but 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 belong to the scope of the present invention.

As described above, according to the surface light source using the white LED according to the present invention and the LCD backlight unit having the same, it is possible to obtain a uniform white light in the entire surface through the proper arrangement of the white LED.

And, unlike the conventional surface light source consisting of a combination of red, green and blue LEDs, the present invention uses only one-chip, that is, white LEDs, so there is little restriction on the arrangement of the LEDs. The advantage is simple and simple circuit configuration.

In addition, the present invention can provide a uniform white light on the front of the LCD panel, there is an effect that can implement a clearer LCD image.

Claims (8)

Arrange a plurality of white LEDs at predetermined intervals, The white light such that the central light amount of the LED unit consisting of each white LED and a combination of any white LEDs arranged at the shortest distance therefrom is 80% to 120% of the average of the total amount of light emitted from each white LED. Surface light source using a white LED, characterized in that the arrangement of the LED. The method of claim 1, The alignment control of the white LED, the surface light source using a white LED, characterized in that for adjusting the row spacing, column spacing and the angle of placement between the white LED. The method of claim 1, The LED unit has a surface light source using a white LED, characterized in that it has any one shape selected from the group consisting of polygons, circles and combinations thereof. The method of claim 1, The white LED is a surface light source using a white LED, characterized in that consisting of a blue LED chip, a red phosphor and a green phosphor. The method of claim 4, wherein The red phosphor is CaAlSiN ₃ : Eu having a nitride-based composition, or (Ca, Sr) S: Eu having a sulfide-based composition. The method of claim 4, wherein The green phosphor is (Sr, Ba) ₂ SiO ₄ : Eu of silicate-based composition, SrGa ₂ S ₄ : Eu of sulfide-based composition, and Beta-SiAlON of nitride-based composition Surface light source using a white LED, characterized in that any one selected from the group consisting of. Board; A reflection plate provided on the substrate; The central light amount of the LED unit which is provided on the reflector, is arranged in a plurality of white LEDs spaced apart by a predetermined distance, and composed of a combination of each white LED and any white LEDs arranged at the shortest distance therefrom, in each white LED A surface light source in which the arrangement of the white LEDs is adjusted to be 80% to 120% of an average value of the total amount of emitted light; A diffusion sheet provided on the surface light source and uniformly diffusing light incident from the surface light source; And A light collecting sheet provided on the diffusion sheet to collect light diffused from the diffusion sheet; LCD backlight unit comprising a. The method of claim 7, wherein LCD backlight unit further comprises a protective sheet provided on the light collecting sheet.

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