KR20080054177A - Backlight unit and backlight unit assembly - Google Patents

Abstract

A backlight unit and a backlight unit assembly are provided to form a bar type lens which covers a plurality of LED(Light Emitting Diode) chips to prevent poor luminance caused by an intensity difference in lights emitted from the plurality of LED chips. A backlight(20) unit includes a bar type substrate(21) on which a circuit pattern for supplying power is formed, a plurality of LED chips(22) arranged along the length direction of the substrate, and a lens(23) formed on the substrate along the length direction of the substrate to cover the plurality of LED chips. The plurality of LED chips are mounted on the substrate and electrically connected to the circuit pattern. The lens diffuses light emitted from the plurality of LED chips.

Description

Backlight Unit and Backlight Unit Assembly {BACKLIGHT UNIT AND BACKLIGHT UNIT ASSEMBLY}

1A and 1B are perspective views of a backlight unit and a backlight unit assembly according to the prior art.

2 is a perspective view of a backlight unit according to a preferred embodiment of the present invention.

3A and 3B are vertical sectional views in the longitudinal direction of the backlight unit according to another embodiment of the present invention.

4A to 4D are cross-sectional views of backlight units having different lens shapes according to the present invention.

5 is a partial plan view and an enlarged view of a backlight unit assembly according to an embodiment of the present invention.

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

21: substrate 22: LED chip

23 lens 24 reflective layer

46: frame

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight such as an LCD (Liquid Crystal Display), and more particularly, a plurality of LED (Light Emitting Diode) chips can be packaged integrally and used as an independent device to obtain uniform light. The present invention relates to a backlight unit and a backlight unit assembly using the same.

Light emitting diodes (hereinafter referred to as 'LEDs') are semiconductor light emitting devices that generate light of various colors by forming light emitting sources by changing compound semiconductor materials such as GaAs, AlGaAs, GaN, InGaN, and AlGaInP. The criteria for determining the characteristics of the LED device include color, luminance, light intensity, and the like, which are primarily determined by the compound semiconductor material used in the LED device. The structure of a package for mounting an LED chip is greatly affected.

In particular, with the emergence of high efficiency three primary colors (red, blue, green) and white light emitting diodes implemented using nitrides having excellent physical and chemical properties, the application range of the light emitting diodes has been expanded, for example, keypads and liquid crystals. It is used in various fields such as a backlight of a display device, a traffic light, a guide light of an airport runway, and an illumination light.

1A and 1B show a backlight unit according to the prior art.

Referring to FIG. 1A, a plurality of LED elements 12 are arranged in a line on the printed circuit board 11. Here, each LED element 12 includes a lens for mounting the LED chip on the frame and for emitting light emitted from the LED chip in the horizontal and vertical directions.

Referring to FIG. 1B, a printed circuit board 11 having the plurality of LED elements 12 arranged therein is mounted in the reflecting plate 13, and the reflecting plate 13 is in a horizontal direction emitted from the LED element 12. The light is reflected in the vertical direction and distributed to the display screen.

According to the conventional technology, the printed circuit board and the reflector have to be redesigned according to the screen size of a display device such as an LCD, and the number of light emitting diode elements used according to the screen size of the display device increases. In addition, if the number of light emitting diode elements is reduced, a bright portion is formed in a portion where the LED element is located, and it becomes difficult to obtain uniform light.

In order to solve the above problems, it is an object of the present invention to provide a backlight unit and a backlight unit assembly having a rod-shaped lens to reduce the difference in luminance caused by the arrangement of the LED chip.

The present invention is a bar-shaped substrate having an upper surface on which a circuit pattern for power supply is formed, and is mounted on the upper surface of the substrate so as to be electrically connected to the circuit pattern, and arranged in a longitudinal direction of the substrate. And a lens formed on an upper surface of the substrate along a longitudinal direction of the substrate so as to cover the plurality of LED chips to diffuse light emitted from the plurality of LED chips.

The vertical cross section with respect to the longitudinal direction of the lens may be semicircular.

Preferably, the lens has a structure having a flat lower surface in contact with the substrate, a flat upper surface parallel to the lower surface, and a plurality of side surfaces connecting the upper surface and the lower surface, and the longitudinal direction of the plurality of side surfaces. Sides formed along the side may be inclined toward the upper portion of the substrate, the side surface in the longitudinal direction of the lens may be a convex curved surface.

It is preferable to further include a reflective layer formed on the upper and lower surfaces of the lens to face each other.

Preferably, the plurality of LED chips are arranged in a line along the longitudinal direction of the substrate.

The substrate may have a groove portion at a position where the plurality of LED chips are mounted. In this case, the groove portion may be extended in a direction in which the plurality of LED chips are arranged, and the lens may have the groove portion. It may be attached to the upper region of the substrate located around the groove portion to cover.

In addition, the present invention, the bar-shaped substrate having a top surface (circuit) formed with a circuit pattern for power supply, and is mounted on the upper surface of the substrate to be electrically connected to the circuit pattern, arranged in the longitudinal direction of the substrate A plurality of backlight units including a plurality of LED chips, and a lens formed on an upper surface of the substrate along a longitudinal direction of the substrate to cover the plurality of LED chips to diffuse light emitted from the plurality of LED chips; And a frame in which the plurality of backlight units are disposed.

Preferably, the plurality of backlight units disposed in the frame are arranged such that a part of each lens overlaps, and the frame includes a plurality of backlight units of the bar-shaped backlight unit disposed at the edge of the frame to adjust uniformity of light. Preferably, a groove is formed in which a portion can be accommodated.

The lens has a structure having a flat lower surface in contact with the substrate, a flat upper surface parallel to the lower surface, and a plurality of side surfaces connecting the upper surface and the lower surface, and formed along a longitudinal direction of the plurality of side surfaces. The side surface may be inclined toward the upper portion of the substrate, the side surface in the longitudinal direction of the lens is preferably a convex curved surface.

More preferably, the upper and lower surfaces of the lens may further include a reflective layer formed to face each other.

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

2 is a perspective view of a backlight unit according to a preferred embodiment of the present invention.

Referring to FIG. 2, the backlight unit 20 according to the present embodiment includes a substrate 21, a plurality of LED chips 22, and a lens 23.

The substrate 21 provides a space in which a plurality of LED chips can be mounted, and a conductive pattern (not shown) capable of transmitting an electrical signal to the LED chip to be mounted is formed. In addition, the substrate 21 also functions to transfer heat generated during the operation of the plurality of LED chips to the outside.

The substrate 21 is formed with a conductive pattern for transmitting an electrical signal, it is preferable that a material having high thermal conductivity efficiency is used. For example, it is preferable to use aluminum (Al).

The substrate 21 has a rod shape, and by using a backlight unit in which an LED chip is mounted on the rod-shaped substrate, the number of backlight units used is adjusted according to the size of a display screen such as an LCD. Unit specifications can be kept constant, reducing design and manufacturing costs.

A plurality of LED chips are mounted on the substrate 21.

The LED chip 22 is connected to the conductive pattern formed on the substrate 21 by wire bonding or flip chip bonding.

A base may be formed between the LED chip 22 and the substrate 21 to dissipate heat generated when the LED chip 22 operates. The base may be made of a material having high thermal conductivity, and may use a material used for a heat sink structure.

The plurality of LED chips are arranged in series, and each LED chip may use an LED chip that emits one of red, green, and blue colors.

A lens 23 covering the plurality of LED chips is formed on the substrate 21.

The lens 23 may be formed of a transparent material that diffuses the light emitted from the LED chip 22 in an upward direction, and preferably, a transparent polymer resin may be used.

The shape of the lens 23 also forms the same bar shape as that of the substrate 21. By using such a rod-shaped lens 23, it is possible to bring about a significant improvement in uniformity compared to a backlight unit in which only LED chips are arranged.

If only the LED chip is arranged, the part where the arranged LED chip is located is brightly lit and the part where the LED chip is not lit is relatively dark, which causes a problem of uniformity. Since there is a need to arrange the manufacturing cost increases.

 In the present embodiment in which a plurality of LED chips are arranged on a bar-shaped substrate and a lens covering the LED chips is formed, light generated from the LED chips is diffused by the lenses, thereby providing uniform light to a display such as an LCD. It can be supplied, resulting in much higher uniformity, even with the same number of LED chips.

The shape of the lens may be implemented in various ways. For example, the vertical section with respect to the longitudinal direction of the lens may be implemented in the form of a semi-circle, triangle, trapezoid, and the like.

When the upper surface of the lens is not flat but curved, the luminous efficiency is low, but there is an advantage in that it is possible to realize uniformity of light.

 In the present embodiment, the lens is formed in a shape in which the upper surface of the lens is cut parallel to the lower surface. A detailed configuration and effects of the rod-shaped lens of which the upper surface is shaved will be described with reference to FIG. 3.

3A is a vertical cross-sectional view of the backlight unit in the longitudinal direction of the preferred embodiment of the present invention.

Referring to FIG. 3A, an LED chip 22 is mounted on a substrate 21, and a lens 23 covering the LED chip 22 is formed.

The lens 23 is sharpened so that the upper surface 23a is parallel to the lower surface 23b in contact with the substrate 21, and the side surface 23c forms a curved surface. In addition, a reflective layer 24 is formed inside the upper surface 23a and the lower surface 23b of the lens.

Light emitted from the LED chip 22 is emitted to the outside through the lens 23, and is largely emitted through two paths.

First, light emitted from the LED chip 22 may pass through a path 27 that is directly emitted to the outside through the side surface 23c of the lens. In this case, the light passing through the side surface 23c of the lens by the angle of light emitted from the LED chip 22 is directed toward the side of the LED chip 22.

In addition, the light emitted from the LED chip 22 may be reflected by the reflective layer 24 formed on the upper surface 23a and the lower surface 23b of the lens to pass through the path 28 passing through the side surface 23c of the lens. have. In this case, the light emitted from the LED chip 22 reaches the upper surface 23a of the lens and is reflected by the reflective layer 24 formed inside the upper surface 23a of the lens, and the reflected light is reflected by the lens. It reaches the lower surface 23b and is reflected by the reflective layer 24 formed inside the lower surface 23b of the lens and emitted to the outside through the side surface 23c of the lens.

Therefore, when the backlight unit according to the present embodiment is used, light is not emitted to the upper surface of the backlight unit but to the left and right side upper surfaces.

In a display using a plurality of backlight units according to the present embodiment, the light illuminated on the upper surface of the LED chips of the plurality of backlight units is not directly emitted from the LED chips arranged at the portion thereof, but adjacent backlight units. The light emitted from the LED chip.

Therefore, in the case where a plurality of backlight modules of the present embodiment are used in an array, uniform light can be obtained while overcoming the unevenness of luminance generated by the arrangement of the LED chips.

As described above, in the present embodiment, a rod-shaped lens is used to eliminate unevenness of luminance that may be generated by the arrangement of the LED chips with respect to the longitudinal direction of the rod-shaped backlight module, and by the arrangement of the rod-shaped backlight module In order to eliminate unevenness of luminance that may occur, the shape of the lens is changed to direct the direction of light emission toward the side surface of the portion where the LED chips are arranged.

3B is a vertical cross-sectional view of the backlight unit according to another embodiment of the present invention in the longitudinal direction.

In the case of this embodiment, it is the same as FIG. 3A except the groove part 31a in which the LED chip 32 can be mounted is formed on the board | substrate 31. FIG.

Since the LED chip 32 is mounted in the groove part 31a, the lens 33 covering the LED chip 32 is formed to be spaced apart from the LED chip 32. That is, the lens 33 formed on the upper surface of the substrate 31 on which the LED chip 32 is mounted is formed in contact with an area excluding the groove portion 31a of the substrate.

The upper surface 33a of the lens 33 and the lower surface 33b formed to be in contact with the substrate are formed in parallel, and a reflective layer 34 is formed inside thereof to reflect light emitted from the LED chip 32.

4A to 4D illustrate various forms of a backlight unit lens according to an embodiment of the present invention. In this way, various light emission characteristics may be exhibited by changing the shape of the lens.

4A is manufactured so that the cross section of the lens is in the shape of a semicircle having a radius R and a height H. FIG. FIG. 4B is a view in which the upper portion of the lens of FIG. 4A is horizontally cut off and a reflective layer is formed on the cut upper surface.

The result of measuring uniformity by placing the plurality of backlight units having the lens shape of FIG. 4A in a frame of 400 × 700 mm is 73.3%, and the plurality of backlight units having the lens shape of FIG. 4B in the same size frame The uniformity of the backlight unit is 82.6%.

Therefore, it can be seen that the uniformity of the backlight unit is increased when the upper portion of the lens is cut parallel to the lower surface and the reflective surface is formed.

As a result of measuring the uniformity by placing a plurality of backlight units having the lens shapes of FIGS. 4C and 4D in the same sized frame as above, it is 76.6% in the case of FIG. 4C, and in the case of FIG. 4D. 85%.

As described in the above embodiment, if the cross-sectional shape of the lens has the same height, it is advantageous for the uniformity to have a short radius.

5 is a structural diagram of a backlight unit assembly in which a bar-shaped backlight unit according to an embodiment of the present invention is disposed in a frame.

Referring to FIG. 5, the backlight unit assembly 40 according to the present embodiment includes a plurality of bar-shaped backlight units and a frame in which the plurality of backlight units are disposed.

The bar backlight unit may have difficulty in arranging a plurality of bar backlights due to poor chromaticity of the end of the bar where the LED light source is disposed when a single backlight unit is used.

In the present embodiment, the plurality of bar-shaped backlight unit 20, the end of the lens is disposed to overlap each other in order to increase the uniformity of the entire backlight. The degree of overlap can be adjusted for uniformity, and the distance between the lenses on both sides can be properly positioned in consideration of the uniformity of the entire backlight assembly. Although not shown in the drawing, an LED driver for driving the LED is further provided, and the color reproducibility and the brightness may be adjusted by adjusting the driving voltage.

As such, the arrangement of the bar-shaped backlight units in the frame 46 may be implemented in various forms.

The frame 46 in which the bar backlight unit 20 is disposed has a groove 46a in which a portion of the bar backlight unit 20 can be inserted.

If the uniform brightness is not obtained from the lens of the bar-shaped backlight unit 20, the uniform brightness may be obtained by overlapping the lenses or adjusting the distance between the lenses at a portion other than the edge of the frame 46. Can be. However, since the corner portion of the frame 46 does not have such a space, a groove is formed in the corner portion to make this space. A portion of the bar backlight unit 20 may be disposed in the groove 46a, and the bar backlight unit 20 may be moved along the free space of the groove 46a. The uniformity of the light may be controlled by adjusting the depth and width according to the degree of uniformity of light emitted from the lens of the bar-shaped backlight unit 20 to secure a space and moving the lens.

As such, the present invention is not limited by the above-described embodiment and the accompanying drawings. That is, the shape of the lens, the arrangement of the LED and the arrangement of the bar-shaped backlight unit may be variously implemented. It is intended that the scope of the invention be defined by the appended claims, and that various forms of substitution, modification, and alteration are possible without departing from the spirit of the invention as set forth in the claims. Will be self-explanatory.

According to the present invention, by forming a backlight unit having a rod-shaped lens covering a plurality of LED chips, it is possible to eliminate a defect in luminance caused by the difference in the intensity of emitted light in the arrangement of the LED chips.

In addition, by arranging a plurality of bar-shaped backlight units, it is possible to implement a backlight unit assembly for screens of various sizes.

Claims (15)

A bar substrate having a top surface on which a circuit pattern for power supply is formed; A plurality of LED chips mounted on an upper surface of the substrate to be electrically connected to the circuit pattern and arranged along a length direction of the substrate; And And a lens formed on an upper surface of the substrate along a longitudinal direction of the substrate to cover the plurality of LED chips to diffuse light emitted from the plurality of LED chips. The method of claim 1, And a vertical cross section in the longitudinal direction of the lens is a semicircle. The method of claim 1, The lens, A flat lower surface in contact with the substrate, a flat upper surface parallel to the lower surface, and a plurality of side surfaces connecting the upper surface and the lower surface, The side surface of the plurality of side surfaces formed along the longitudinal direction is inclined toward the upper portion of the substrate. The method of claim 3, The side surface in the longitudinal direction of the lens is a convex curved surface, characterized in that. The method of claim 3, And a reflective layer formed on the upper and lower surfaces of the lens to face each other. The method of claim 1, The plurality of LED chips, The backlight unit, characterized in that arranged in a line along the longitudinal direction of the substrate. The method of claim 1, The substrate, And a groove part at a position where the plurality of LED chips are mounted. The method of claim 7, wherein And the groove portion extends along the arrangement direction of the plurality of LED chips. The method of claim 7, wherein And the lens is attached to an upper region of the substrate positioned around the groove to cover the groove. A bar-shaped substrate having an upper surface on which a circuit pattern for power supply is formed, a plurality of LED chips mounted on the upper surface of the substrate so as to be electrically connected to the circuit pattern, and arranged along a longitudinal direction of the substrate; And a lens formed on an upper surface of the substrate along a length direction of the substrate so as to cover the plurality of LED chips to diffuse light emitted from the plurality of LED chips. And And a frame in which the plurality of backlight units are disposed. The method of claim 10, The plurality of backlight units disposed in the frame, A backlight unit assembly, characterized in that a portion of each lens is disposed so as to overlap. The method of claim 10, The frame, In order to adjust the uniformity of light, a backlight unit assembly, characterized in that a groove is formed to accommodate a portion of the bar-shaped backlight unit disposed on the edge of the frame. The method of claim 10, The lens, A flat lower surface in contact with the substrate, a flat upper surface parallel to the lower surface, and a plurality of side surfaces connecting the upper surface and the lower surface, The side surface of the plurality of side surfaces formed along the longitudinal direction is inclined toward the upper portion of the substrate. The method of claim 13, The side surface in the longitudinal direction of the lens is a convex curved surface, characterized in that. The method of claim 13, And a reflective layer formed on the upper and lower surfaces of the lens to face each other.

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