KR20080022273A - Backlight unit, liquid crystal display module including the same - Google Patents

Abstract

A backlight unit, and a liquid crystal display module including the same are provided to arrange light emission diodes in parallel without width increment of the module for preventing all diodes from being off when some of the diodes are damaged and to recognize the diodes easily by grouping the diodes by predetermined order. A backlight unit(120) comprises light emission diodes(124), and a printed circuit board(126). The printed circuit board is arranged with the diodes in a row, grouped electrically, and formed with the plural groups in parallel. A liquid crystal display module includes a liquid crystal panel(110), a support main(130), the backlight unit, a cover bottom(140), and a top cover. The support main covers edges of the panel. The top cover surrounds the front edges of the panel. Thereby, the light emission diodes are easily recognized in parallel.

Description

Backlight unit, Liquid crystal display module including the same {Backlight unit, Liquid crystal display module including the same}

1 is a view illustrating a general liquid crystal display module.

2A and 2B schematically illustrate a printed circuit board on which a general light emitting diode is mounted and a light emitting diode used in the present invention.

FIG. 3 is a diagram schematically illustrating a pad of a printed circuit board in which light emitting diodes are connected in parallel and a power wiring thereof.

4 is a schematic view of a portion of a liquid crystal display module according to an embodiment of the present invention.

5A and 5B illustrate an arrangement of pads formed on a printed circuit board of a backlight unit and power supply wirings connecting the pads according to an embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

110: liquid crystal panel 112: flexible circuit board

114: driving circuit 120: backlight unit

122: reflector 124: light emitting diode

125: printed circuit board 126: light guide plate

128: optical sheet 130: support main

140: cover bottom 145: lamp housing

The present invention relates to a backlight unit, a liquid crystal display module including the same, and more particularly, to a backlight unit utilizing a plurality of light emitting diodes as a light source, and a liquid crystal display module including the same.

A general liquid crystal display device has an image realization principle using optical anisotropy and polarization property of liquid crystal. As is well known, liquid crystal has a thin and long molecular structure and has an optical anisotropy having an orientation in an array and a molecular arrangement depending on its size when placed in an electric field. It is polar in nature with its changing direction.

Accordingly, a liquid crystal display device includes a liquid crystal panel in which a pair of substrates on which a transparent field generating electrode is formed on a surface facing each other with a liquid crystal layer interposed therebetween, and a backlight unit for supplying light thereto. Unit) and a driving circuit for driving the same, and by adjusting the arrangement direction of the liquid crystal molecules according to the electric field size between the two field generating electrodes of the liquid crystal panel so that the transmittance is different, the light emitted from the backlight unit is added thereto. Various target images are displayed by passing through such that the difference in transmittance is expressed to the outside.

Such a liquid crystal display device is a side light type that enters the front side of the liquid crystal panel by refracting the light of the backlight lamp disposed at one side edge of the liquid crystal panel with the light guide plate according to the arrangement method of the backlight lamp included in the backlight unit. light type) or a plurality of backlight lamps arranged on the rear surface of the liquid crystal panel, and thus, may be classified into a direct type for directly supplying light over the entire liquid crystal panel.

The metering type liquid crystal display device is provided with a tubular backlight lamp on the side of the liquid crystal panel, and uses a transparent light guide plate to project light from the lamp onto the entire liquid crystal panel screen. A plurality of backlight lamps are arranged in a row on the lower surface to directly irradiate light to the front of the liquid crystal panel.

The liquid crystal panel and the backlight unit are modularized by mobilizing various mechanical elements to protect them and to prevent light loss.

Hereinafter, these are collectively referred to as a liquid crystal display module.

1 is a diagram illustrating a general liquid crystal display device module, in which the liquid crystal panel 10 and the backlight unit 20 are generally modularized by mobilizing various mechanical elements.

As shown in the drawing, the general liquid crystal display module covers the edges of the main body of the liquid crystal panel 10 and the backlight unit 20 up and down to cover the edges of the support main 30. A cover bottom 40 serving as a bottom surface is located on the rear surface of the backlight unit 20 to be combined with the support main 30, thereby constituting an overall shape and minimizing light loss, and integrating all of them. The top cover 50 having a rectangular frame shape covering the front edge and the side surface of the liquid crystal panel 10 is assembled to the support main 30 and the cover bottom 40 so as to be formed.

At this time, the driving circuit 14 is connected to at least one side of the liquid crystal panel 10 via a flexible printed circuit board 12, which is the outer side of the support main 30 or the cover bottom in the assembling process. The back of the 40 is properly flipped and adhered.

The backlight unit 20 may include a white or silver reflective sheet 22 covering the inner surface of the cover bottom 40, and a backlight lamp arranged along an inner length direction of at least one edge of the support main 30. 23 and a light guide panel 26 having a predetermined thickness in which at least one side thereof faces the backlight lamp 23 by being seated on the reflective sheet 22 so as to have the same plane position as the backlight lamp 23. And a plurality of optical sheets 28 covering the light guide plate 26, wherein the light emitted from the backlight lamp 23 is concentrated along the side of the light guide plate 26 along the longitudinal direction of the backlight lamp 23. The lamp housing 45 is provided to surround the upper and lower three directions.

Here, the backlight lamp is a light source for generating light, and generally, a cold cathode fluorescent lamp (CCFL) or an external electrofluorescent lamp (EEFL) is widely used.

Currently, as part of a high-brightness backlight lamp, a number of lamps are placed on the lower side of the display screen or one lamp is bent and placed in order to implement a backlight lamp. Is in.

Accordingly, the backlight unit has recently formed a thinner light guide plate due to various requirements such as design, low power consumption, and thinning, and is capable of expressing various colors, as well as a light emitting diode, which is a discontinuous light emitting device. The development of technology for improving the display quality using the following) is proposed.

2A and 2B schematically illustrate light emitting diodes generally used as backlight lamps and printed circuit boards on which the light emitting diodes are mounted. As shown in FIG. 2A, the light emitting diodes 24 have a large number. The dogs are bonded in a row on the printed circuit board 25, and the printed circuit board 25 is provided in the form of standing on one side end of the liquid crystal display cover bottom (40 in FIG. 1).

In addition, as shown in FIG. 2B, the light emitting diode (24 of FIG. 2A) has a rectangular package having a length of 3.5 mm × 3.5 mm in width × length, and has a separation distance between the anode and the cathode electrode disposed on the rear surface thereof. 1.6mm.

In this case, a metal core PCB (Metal Core PCB) is generally used for the printed circuit board 25, which inevitably increases the internal temperature when the luminance increases due to the characteristics of the light emitting diode 24. Since the luminance is sharply lowered, it is for quickly dissipating the heat of junction resistance due to its light emission to the outside.

Since the plurality of light emitting diodes 24 are electrically connected in series, when one light emitting diode 24 is damaged, the entire backlight lamp does not operate. Thus, each light emitting diode ( 24, a parallel connection method has been proposed.

FIG. 3 is a view schematically illustrating a pad of a printed circuit board in which light emitting diodes are connected in parallel and a shape of power supply wirings thereof. An anode and a cathode of the light emitting diode (24 of FIG. 2b) may be formed on the printed circuit board 25. In order to correspond to the electrodes, the first and second pads a and c are formed in a form of '∥', and the first and second pads a and c are electrically connected to each other by power supply wiring. Here, the minimum line width and the minimum distance between the power lines are about 0.2 mm, respectively.

Accordingly, a plurality of light emitting diodes mounted on the printed circuit board 25 may be connected in parallel, but the power supply wirings connecting the first and second pads a and c may be surrounded by the outer edge of the electrode so as not to overlap. The width d of the printed circuit board 25 is widened accordingly.

Here, as described above, the printed circuit board 25 is provided to stand on one side of the liquid crystal display cover bottom, which causes the thickness of the liquid crystal display module to increase.

The present invention provides a backlight unit having a light emitting diode connected in parallel to minimize the effect of the breakage of some lamps on the operation of the entire backlight lamp without increasing the thickness of the liquid crystal display module, and a liquid crystal display module including the same Its purpose is to.

Another object of the present invention is to provide a method of detecting a light emitting diode position of a backlight unit that can easily detect the positions of some light emitting diodes of the same group as any of the light emitting diodes selected by the identifier when the light emitting diodes are broken. have.

In order to achieve the above object, the backlight unit according to an embodiment of the present invention, a light emitting diode; The light emitting diodes are arranged in a line, and are defined as a plurality of groups electrically connected in series, and the plurality of groups includes a printed circuit board formed in parallel connection.

The printed circuit board includes a power supply unit provided at an outside; A first pad sequentially disposed from the left end to the right end; A second pad disposed to face the first pad; A power wiring connecting the power supply unit and the first pad by the number of electrical groups; A connection wiring connecting the second pad to a first pad of the same electrical group disposed at a right end of the first pad connected to the power wiring; The power supply wiring and the connection wiring may be disposed across the separation space formed by the first pad and the second pad facing each other.

The first and second pads may be formed in a '〓' shape to be parallel to each other in the longitudinal direction of the printed circuit board.

The printed circuit board may be a metal core PCB having a photo solder resist layer formed on an upper surface thereof.

In order to achieve the above object, the liquid crystal display device module according to an embodiment of the present invention, the liquid crystal panel; A support main covering an edge of the liquid crystal panel; A printed circuit board provided on a rear surface of the liquid crystal panel, and light emitting diodes are arranged in a line, the light emitting diodes being defined as a group electrically connected in series, and a predetermined number of the groups formed in parallel connection; A backlight unit comprising a; A cover bottom provided at the top or side of the backlight unit; And a top cover covering the front edge of the liquid crystal panel.

In order to achieve the above another object, according to the embodiment of the present invention, a method of detecting a position of light emitting diodes belonging to the same group of backlight units may include light emitting diodes arranged in a line, and the light emitting diodes may be electrically connected in series. In a backlight unit including a printed circuit board and a predetermined number of groups formed in parallel connection, and a backlight unit including the printed circuit board, a method for detecting a position of light emitting diodes belonging to the same group, the nth selected from an identifier The light emitting diodes of the same group as the first light emitting diode are defined as a variable a having the total number of light emitting diodes being L, the number of groups being m, and increasing by 1,

When the position of the nth light emitting diode is located at the left end of the printed circuit board (n ≦ m), the position of the nth light emitting diode and the same group light emitting diode is in the right direction from the nth light emitting diode. Detecting by the (n + (m × a)) th light emitting diode;

When the position of the nth light emitting diode is located at the center of the printed circuit board (m <n ≤ L-m), the position of the nth light emitting diode and the same group light emitting diode is the nth light emitting diode. Detecting from the left and right directions with the {n ± (m × a)} th light emitting diode,

When the position of the nth light emitting diode is located at the right end of the printed circuit board (n> L − m), the position of the nth light emitting diode and the same group light emitting diode is from the nth light emitting diode. And detecting the light emitting diode of the {n-(m x a)} th light in the right direction.

Hereinafter, a liquid crystal display device according to an embodiment of the present invention, a backlight unit included in the same, and a configuration method thereof will be described with reference to the accompanying drawings.

4 is a view schematically illustrating a part of a liquid crystal display module according to an embodiment of the present invention. Referring to FIG. 4, the liquid crystal panel 110 and the backlight unit 120 are generally integrated with various mechanical elements. Modular to

As shown, a general liquid crystal display device includes a support main 130 having a substantially rectangular frame shape covering the edges thereof with the liquid crystal panel 110 and the backlight unit 120 stacked up and down. A cover bottom 140 serving as a surface is located at the back of the backlight unit 120 to be combined with the support main 130, thereby constituting the overall shape and minimizing light loss, and integrating all of them. The top cover 150 having a rectangular frame shape covering the front edge and the side surface of the liquid crystal panel 110 is assembled to the support main 130 and the cover bottom 140.

At this time, the driving circuit 114 is connected to at least one side of the liquid crystal panel 110 via a flexible printed circuit board 112, which is an outer side of the support main 130 or a cover bottom in an assembling process. Properly tilted to the back of 140).

In addition, the backlight unit 120 includes a white or silver reflective sheet 122 covering the inner surface of the cover bottom 140, and a printed circuit board arranged along an inner length direction of at least one edge of the support main 130. 126 and a plurality of light emitting diodes 124 mounted on the printed circuit board 126 and at least one side surface by being seated on the reflective sheet 122 so as to have the same plane position as the printed circuit board 125. A light guide panel 126 having a predetermined thickness facing the printed circuit board 125, and a plurality of optical sheets 128 covering the light guide plate 126, in addition to the light emitting diodes 124. The lamp housing 145 is formed in a shape in which one side of the cover bottom 140 is bent to surround the upper and lower three directions along the longitudinal direction of the printed circuit board 124 so that the light emitted from the light guide plate 126 is concentrated on the side of the light guide plate 126. . Here, the lamp housing 145 may be provided separately from the cover bottom 140.

The light emitting diode is a solid-state device using a photoelectric conversion effect of a semiconductor, a semiconductor device that emits light generated by the difference in energy when electrons recombine with holes when a forward voltage is applied, and uses a tungsten filament that heats and emits filaments. Since it is driven at a lower voltage than a lamp, it has been widely used in various display devices for a long time.

In order to emit light of the light emitting diode, a DC voltage of about V may be applied, and thus, a DC-AC converter, which is necessarily included in a conventional CCFL or EEFL lamp, is not necessary. In addition, since the light emitting diode is a semiconductor device, it has advantages of higher reliability, smaller size, and longer life than other lamps.

Here, a plurality of light emitting diodes 124 are bonded in a row on the printed circuit board in the same manner as in the related art, as shown in FIG. 2A.

However, the light emitting diodes 124 are not electrically connected to light emitting diodes that are closest to each other, but are electrically connected to light emitting diodes bonded to each other by a predetermined distance, which is defined as a group.

To this end, the printed circuit board 125 forms pads formed so as to correspond to the anode and cathode electrodes of the light emitting diode, and power wirings electrically connecting the pads form a predetermined group connected in series.

Hereinafter, a backlight unit included in a liquid crystal display module according to an exemplary embodiment of the present invention and a method of configuring the same will be described.

5A and 5B illustrate an arrangement structure of pads formed on a printed circuit board of a backlight unit and power supply wirings connecting the pads according to an embodiment of the present invention, corresponding to anode and cathode electrodes of a light emitting diode. The first and second pads (a, c) are arranged in a line '〓' on the printed circuit board 124.

More specifically, as shown in FIG. 5A, a power supply unit (not shown) provided in the printed circuit board, the first pads (a) sequentially disposed from the left end to the right end of the printed circuit board, are provided externally by the number of electrical groups. And a second pad c facing the first pad are sequentially connected to the first pad a of the same group from the left end to the right end of the printed circuit board.

In this case, the connection wiring with the first pad a extending from the second pad c is disposed across the separation space where the first and second pads of different groups face each other.

For example, as shown in FIG. 2B, when using a light emitting diode of a rectangular package having a length × length of 3.5 mm × 3.5 mm, the light emitting diode has a separation distance between the anode and the cathode electrode disposed downward. It is about 1.6 mm, and the minimum line width of the power supply wiring and the minimum distance between wirings are each about 0.2 mm. Accordingly, the pads on the printed circuit board corresponding to the two electrodes are also formed in the same standard, and since three wires can be arranged between the pads, a total of three electrical groups can be formed.

Therefore, the greater the number of groups formed on one printed circuit board and the smaller the number of light emitting diodes corresponding to one group, the more advantageous.

Referring to an equivalent circuit diagram of a light emitting diode having such a structure, as shown in FIG. 5B, each of the light emitting diodes D1 to Dn is alternately connected between neighboring light emitting diodes, and is connected in series to the same group.

 For example, when the third light emitting diode D3 is damaged, the sixth light emitting diode D6 connected in series with the light emitting diode D3 and the third nth light emitting diode {D (3n) (not shown) are not shown. } Only turns off (n = 1, 2, 3)

In the conventional printed circuit board on which the light emitting diodes are mounted, as described above, a metal core PCB is used, and a photo solder resist (PSR) layer is formed on the upper surface thereof. It is difficult to visually identify the type of connection. Therefore, when some of the light emitting diodes are damaged, the entire light emitting diodes should be inspected. Hereinafter, an equation for easily identifying the positions of light emitting diodes in the same group as the nth light emitting diodes on a printed circuit board is proposed.

First, light emitting diodes belonging to the same group are spaced apart from the nth light emitting diode arbitrarily selected by the identifier by the number m of the groups. Therefore, when the position value n of the nth LED is multiplied by the number value m of the group, which is increased or decreased by 1, the position value A of the LEDs belonging to the same group is obtained. You can get it.

A = n ± (m × a) ............. Equation 1

For example, when the number of groups is 3 (m = 3) and the position value A of the light emitting diodes belonging to the same group as the 54th light emitting diode (n = 54) is a = 1 according to Equation 1, A = 51 and 57, and when a = 2, the values A = 48 and 60 are obtained.

Here, when the position value n of the nth light emitting diode is less than or equal to the number value m of the group (n ≦ m), the nth light emitting diode is located at the leftmost end of the group. In this case, since there is no light emitting diode in the previous stage, the position value n of the nth light emitting diode and the number value m of the group are multiplied by the value a which increases by 1 (m). X a) By adding these two values, the position value A of the light emitting diodes belonging to the same group can be obtained.

A = n + (m × a) ............. Equation 2

For example, when the number of groups is 3 (m = 3) and the position value A of the light emitting diodes belonging to the same group as the first light emitting diode (n = 1) is a = 1 according to Equation 2, If A = 4 and a = 2, A = 7.

Further, when the position value n of the nth light emitting diode is larger than the total number of lamps L bonded on the printed circuit board L is subtracted from the number value m of the group (n> L-m), The nth light emitting diode is a light emitting diode positioned at the rightmost end of the group. In this case, since there is no light emitting diode at the next end, the position value n of the nth light emitting diode and the number of groups are determined. By multiplying (m) by a value (a) that is incremented by one (m × a), subtracting these two values yields the position (A) of the lamps in the same group.

A = n-(m × a) ............. Equation 3

For example, the number of groups is 3 (m = 3), the total number of lamps is 80 (L = 80), and the position value A of the light emitting diodes belonging to the same group as the 78th light emitting diode (n = 78) is According to Equation 1, when a = 1, A = 75, and when a = 2, A = 72.

Accordingly, when the number of electrical groups formed by the printed circuit board and the number of light emitting diodes included in the group are provided, the relative positions of the light emitting diodes connected to any one of the plurality of light emitting diodes bonded on the printed circuit board are determined. It can be easily identified.

In addition, in the above description, a light-emitting type liquid crystal display module has been described as an example. However, this is a direct type liquid crystal display module in which a plurality of printed circuit boards on which light emitting diodes forming one line are disposed is disposed above the cover bottom. This can also apply.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the present invention described in the claims below I can understand that you can.

Therefore, the liquid crystal display device module according to the embodiment of the present invention, the backlight unit included in the same, and a method of configuring the same are electrically connected to each other by forming connection wirings of the printed circuit board pads to which the light emitting diodes are bonded between the pads. The printed circuit board width is not increased.

Accordingly, the light emitting diodes may be connected in parallel without increasing the width of the liquid crystal display module.

In addition, it is possible to prevent all the light emitting diodes from being turned off when a part of the bonded light emitting diodes is broken.

In addition, the light emitting diodes are electrically grouped according to a certain rule, which makes it easy to identify the light emitting diodes belonging to the same electrical group.

Claims (6)

A light emitting diode; A printed circuit board in which the light emitting diodes are arranged in a line and defined as a plurality of groups electrically connected in series, wherein the plurality of groups are formed in parallel connection; Backlight unit comprising a. According to claim 1, The printed circuit board, A power supply unit provided outside; A first pad sequentially disposed from the left end to the right end; A second pad disposed to face the first pad; A power wiring connecting the power supply unit and the first pad by the number of electrical groups; A connection wiring connecting the second pad to a first pad of the same electrical group disposed at a right end of the first pad connected to the power wiring; The power supply line and the connection line, the backlight unit, characterized in that disposed across the separation space formed facing the first pad and the second pad. The method of claim 2, The first and second pads, the backlight unit, characterized in that formed in the '〓' shape to face parallel to the longitudinal direction of the printed circuit board. The method of claim 2, The printed circuit board is a backlight unit, characterized in that the metal core PCB with a photo solder resist (Photo Solder Resist) layer formed on the upper surface. In the backlight unit including the printed circuit board and the printed circuit board, wherein the light emitting diodes are arranged in a line, the light emitting diodes are defined as a group electrically connected in series, and the group is formed in a parallel connection. As a method of detecting the position of the lamp belonging to the group, Suppose that the light emitting diodes of the same group as the nth light emitting diode selected from the identifier are defined by a variable a having a total number of light emitting diodes L, a number of groups increasing by m, 1, When the position of the nth light emitting diode is located at the left end of the printed circuit board (n ≦ m), the position of the nth light emitting diode and the same group light emitting diode is in the right direction from the nth light emitting diode. Detecting by the (n + (m × a)) th light emitting diode; When the position of the nth light emitting diode is located at the center of the printed circuit board (m <n ≤ L-m), the position of the nth light emitting diode and the same group light emitting diode is the nth light emitting diode. Detected by the {n ± (m × a)} th light emitting diode in the left and right directions, When the position of the nth light emitting diode is located at the right end of the printed circuit board (n> L − m), the position of the nth light emitting diode and the same group light emitting diode is from the nth light emitting diode. Detecting the light emitting diode of the {n-(m x a)} th light in the right direction; Method of detecting a light emitting diode position belonging to the same group of the backlight unit, characterized in that it comprises a. A liquid crystal panel; A support main covering an edge of the liquid crystal panel; A printed circuit board provided on a rear surface of the liquid crystal panel, and light emitting diodes are arranged in a line, the light emitting diodes being defined as a group electrically connected in series, and a predetermined number of the groups formed in parallel connection; A backlight unit comprising a; A cover bottom provided at the top or side of the backlight unit; A top cover covering the front edge of the liquid crystal panel; Liquid crystal display module comprising a.

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