KR101043681B1 - Backlight unit for liquid crystal display - Google Patents

Abstract

The present invention relates to a backlight unit for a liquid crystal display device. A backlight unit for a liquid crystal display according to an exemplary embodiment of the present invention includes a plurality of U-shaped fluorescent lamps having first and second electrodes formed at both ends thereof, a first electrode line applying an alternating voltage to the first electrode, and a second A second electrode line configured to apply an inverted alternating voltage to the electrode is configured, and the first wiring connecting the first electrode lines and the second wiring connecting the second electrode lines include a printed circuit board patterned to be spaced apart from each other. .

Liquid Crystal Display, Backlight Unit, Inverter

Description

Backlight unit for liquid crystal display

1A to 1C are diagrams illustrating a conventional backlight unit for a liquid crystal display device.

2 is a block diagram illustrating a backlight unit for a liquid crystal display according to an exemplary embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

100: U-shaped fluorescent lamp

110: printed circuit board

111: first electrode wire

112: second electrode wire

113: first wiring

114: second wiring

120: insulator

130: first transformer

131: second transformer

140: connector

The present invention relates to a backlight unit for a liquid crystal display, and more particularly, to properly adjust the crossing order of the electrode lines connected to the external electrode of the U-shaped fluorescent lamp, and to generate an alternating voltage to apply to the external electrode through the electrode lines. By using an insulator for an inverter, the present invention relates to a backlight unit for a liquid crystal display device configured to be operated more stably by removing adverse effects that may occur when electrode lines to which high voltage alternating voltage is applied cross or approach.

In today's information society, the role of electronic displays has become very important, and various electronic displays have been widely used in various industrial fields. In the electronic display device field, electronic display devices having new functions suitable for the demands of the information society, which have been continuously developed and diversified, are continuously being developed. In general, an electronic display device refers to a device that transmits various pieces of information to a human through vision. That is, an electronic display device refers to an electronic device that converts an electronic information signal output from various electronic devices into an optical information signal that can be recognized by a human vision. It can be said.

In such an electronic display device, when an optical information signal is displayed by a light emitting phenomenon, it is referred to as a light emitting display device, and when it is displayed by light modulation due to reflection, scattering, or interference phenomenon, it is called a light receiving display device. Light emitting displays, also called active display devices, include cathode ray tubes (CRTs), plasma display panels (PDPs), organic electroluminescent displays (OELDs), and light emitting diodes (LEDs). Light Emitting Diode (LED) etc. can be mentioned. The light receiving display device, which is called a passive display device, may include a liquid crystal display (LCD), an electrophoretic image display (EPID), and the like.

Cathode ray tube display device, which is used for television and computer monitor, and has the longest history, has the highest market share in terms of economy, but has many disadvantages such as heavy weight, large volume and high power consumption. .

Recently, due to the rapid progress of semiconductor technology, there is a demand for a flat panel display device as an electronic display device suitable for a new environment in accordance with the trend of lowering and lowering power of various electronic devices and miniaturization, thinning, and lightening of electronic devices. It is rapidly increasing. Accordingly, flat panel display devices such as a liquid crystal display (LCD), a plasma display device (PDP), an organic EL display device (OELD), and the like have been developed, and among these flat panel display devices, it is easy to miniaturize, light weight, and thinner. In particular, liquid crystal display devices having low power consumption and low driving voltage are drawing attention.

In the liquid crystal display, a liquid crystal material having an anisotropic dielectric constant is injected between an upper transparent insulating substrate on which a common electrode, a color filter, a black matrix, and the like are formed, and a lower transparent insulating substrate on which a switching element and a pixel electrode are formed. By applying different potentials to the electrodes and the common electrode, the intensity of the electric field formed in the liquid crystal material is adjusted to change the molecular arrangement of the liquid crystal material, thereby controlling the amount of light transmitted through the transparent insulating substrate to express a desired image. It is a display device. Since the liquid crystal display is a light-receiving display device that does not emit light by itself, a back light unit (BLU) is installed on the back of the liquid crystal display panel that displays an image and maintains the brightness of the entire screen uniformly. Doing.

A backlight unit for a conventional liquid crystal display device will be described with reference to FIGS. 1A to 1C. 1A to 1C are diagrams illustrating a conventional backlight unit for a liquid crystal display device.

As a conventional backlight unit, a light guide plate method of converting a light source installed at a side surface into a planar light source by a light guide plate and a direct type method of installing a light source at a rear surface thereof are used. Fluorescent lamps used as light sources in direct-type backlight units are classified into cold cathode fluorescent lamps (CCFLs) and external electrode fluorescent lamps (EEFLs). In general, a plurality of fluorescent lamps are provided.

FIG. 1A illustrates a conventional backlight unit for a liquid crystal display device using a linear cold cathode fluorescent lamp as a light source, and FIG. 1B illustrates a conventional backlight unit for a liquid crystal display device using a linear external electrode fluorescent lamp as a light source. It is shown.

In a conventional backlight unit for a liquid crystal display using a cold cathode fluorescent lamp as a light source, as shown in FIG. 1A, electrodes 11 are disposed at both ends of a tube to emit light when power is supplied to the electrodes 11. A plurality of cold cathode fluorescent lamps (10) and a plurality of inverters (12) for converting a DC voltage into an alternating voltage to supply to each cold cathode fluorescent lamp (10).

The cold cathode fluorescent lamp 10 is coated with a fluorescent material on the inner wall of the tube, and the electrode 11, which is a conductor, is electrically formed at both ends thereof. The inverter 12 converts and supplies a DC voltage provided from an AC adapter or a battery into an AC voltage having a constant frequency and voltage level suitable for driving the cold cathode fluorescent lamp 10. In addition, the screen brightness of a liquid crystal display panel (not shown) provided in the liquid crystal display to display an image controls the switching frequency of the inverter 12 to adjust the amount of alternating current supplied to the cold cathode fluorescent lamp 10. By doing. Here, the electrode line 13 protrudes outward from the cold cathode fluorescent lamp 10 to connect the protruding electrode lines 13 by soldering, thereby connecting the inverter 12 to the cold cathode fluorescent lamp 10. Each of the cold cathode fluorescent lamps 10 may be individually driven since the inverters 12 are connected to the respective inverters 12.

In the conventional backlight unit for a liquid crystal display device using a linear external electrode fluorescent lamp as a light source, as illustrated in FIG. 1B, a plurality of external electrode fluorescent lamps 20 having external electrodes 21 disposed at both ends of the tube are provided. ), And the plurality of external electrode fluorescent lamps 20 are connected to one inverter 23 in parallel through the external electrode 21 and the connection module 22. The external electrode fluorescent lamp 20 is coated with a fluorescent material on the inner wall of the tube, and filled with argon (Ar), neon (Ne), mercury (Hg) gas, or the like as a discharge gas in the inner space.

The external electrode fluorescent lamp 20 is connected using an external electrode 21 formed of a pole plate on the outer wall of the tube, unlike ordinary fluorescent lamps or similar luminaires, and a plurality of external electrode fluorescent lamps 20 are arranged in parallel to exchange a DC voltage. It has a structure connected to the output terminal of the inverter 23 to convert the voltage to output. In this structure, the external electrode 21 and the external electrode 21 of the same external electrode fluorescent lamp 20 are connected in series, and each external electrode fluorescent lamp 20 is connected in parallel. Here, the entire external electrode fluorescent lamps 20 may be driven at a time by using one inverter 23 due to the characteristics of the external electrode fluorescent lamp 20, and thus, as illustrated in FIG. The external electrodes 21 formed at one end and the other end of the 20) are inserted into the connection module 22 made of a predetermined shape of the instrument and connected to the inverter 23 in common. The external electrode fluorescent lamp 20 is advantageous to operate in parallel because the electrode is external, unlike the cold cathode fluorescent lamp in which the electrode is inside the tube, and reduces the voltage deviation generated between each external electrode fluorescent lamp 20 Luminance can be achieved.

In addition, the liquid crystal display device adopts a split driving method of improving luminance and obtaining better image quality by dividing and driving the entire area of the liquid crystal display panel displaying an image into several unit blocks in the horizontal or vertical direction. In the divided driving method, a backlight unit having a plurality of U-shaped fluorescent lamps is used to individually control whether light is generated for each unit block.

Fig. 1C shows a conventional backlight unit for a liquid crystal display device using a U-shaped fluorescent lamp as a light source, and shows a case where a cold cathode fluorescent lamp is used as a U-shaped fluorescent lamp.

In a conventional backlight unit for a liquid crystal display device using a U-shaped fluorescent lamp as a light source, as shown in FIG. 1C, a fluorescent material is coated on an inner wall of a tube, and an electrode 31, which is a conductor, is electrically connected to both ends of the inside of the tube. A plurality of U-shaped fluorescent lamps 30 formed therein, a connector 32 connected to both electrodes 31 of each U-shaped fluorescent lamp 30 to supply power, and a direct current provided from an AC adapter or a battery. An inverter 33 for converting the voltage into an alternating voltage having a constant frequency and voltage level suitable for driving the U-shaped fluorescent lamp 30 is provided.

When each connector 32 connected to both electrodes 31 of the U-shaped fluorescent lamp 30 is connected to the inverter 33, an alternating current flows through the connected connector 32 to the U-shaped fluorescent lamp 30. The U-shaped fluorescent lamp 30 emits light.

By the way, in the case of using a cold cathode fluorescent lamp as the U-shaped fluorescent lamp 30, a cylindrical electrode (usually a nickel electrode is used) is provided on the inner wall of both ends of the tube, and light is discharged by voltage discharge through the electrode. Due to the characteristics of the cold cathode fluorescent lamp to be generated, it is very difficult to install the electrodes on the inner wall of both ends of the tube, and there is a problem in that the junction between the electrode and the tube is easily damaged and the life is shortened.

On the other hand, the external electrode fluorescent lamp seals the tube, installs an external electrode on both ends of the tube, and forms an electric field inside the tube by capacitive coupling between the external electrode and the outer wall of the tube. To generate light. Such external electrode fluorescent lamps have the advantages of longer life, lower power consumption, and uniform brightness than cold cathode fluorescent lamps.

Therefore, even in applying the split driving method, it is possible to utilize these advantages by using an external electrode fluorescent lamp as the U-shaped fluorescent lamp 30, but the external electrode fluorescent lamp is configured in a form similar to the cold cathode fluorescent lamp of Figure 1c In the case of use, the circuit becomes unstable such that the electrode wires connected to the external electrode and receiving high-voltage alternating voltage intersect or approach each other to generate sparks or cause unnecessary influences.

Therefore, the technical problem to be achieved in the present invention is to configure a U-shaped fluorescent lamp including an external electrode fluorescent lamp for the divided drive of the unit unit of the backlight unit, the cross order of the electrode lines connected to the external electrode of the U-shaped fluorescent lamp By using an insulator in the inverter that adjusts properly and generates AC voltage and applies it to the external electrode through the electrode wires, it operates more stably by eliminating adverse effects that may occur when the electrode wires to which the high-voltage AC voltages are applied cross or come close to each other. Another object of the present invention is to provide a backlight unit for a liquid crystal display device.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned above may be clearly understood by those skilled in the art from the following description. There will be.

According to an aspect of the present invention, there is provided a backlight unit for a liquid crystal display device, the plurality of U-shaped fluorescent lamps having first and second electrodes formed at both ends thereof, and applying an alternating voltage to the first electrode. And a second electrode line configured to apply an inverted alternating voltage to the second electrode, wherein the first wiring connecting the first electrode lines and the second wiring connecting the second electrode lines are spaced apart from each other. And an insulator provided on the printed circuit board and the printed circuit board, wherein the first electrode line or the second electrode line intersects the first wiring or the second wiring.

In the backlight unit for a liquid crystal display according to the exemplary embodiment of the present invention, the plurality of U-shaped fluorescent lamps preferably form a unit block for split driving.

In the backlight unit for a liquid crystal display device according to an embodiment of the present invention, the first electrode of each of the plurality of U-shaped fluorescent lamps is disposed to be adjacent to each other, and the second electrode of each of the plurality of U-shaped fluorescent lamps Is preferably disposed adjacent to each other.

In the backlight unit for a liquid crystal display according to the exemplary embodiment of the present invention, the printed circuit board further includes a connector, and the first electrode line is connected to the first wiring through the connector.

In the backlight unit for a liquid crystal display according to the exemplary embodiment of the present invention, the printed circuit board further includes a connector, and the second electrode line is connected to the second wire through the connector.

In the backlight unit for a liquid crystal display device according to an embodiment of the present invention, the printed circuit board is connected to the first wiring, the first transformer for outputting the AC voltage supplied to the U-shaped fluorescent lamp, the first transformer And a second transformer connected to the second wiring and outputting the inverted alternating voltage to the U-shaped fluorescent lamp.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

Referring to FIG. 2, a backlight unit for a liquid crystal display according to an exemplary embodiment of the present invention will be described. FIG. 2 is a block diagram illustrating a backlight unit for a liquid crystal display according to an exemplary embodiment of the present invention, and illustrates one unit block including four U-shaped fluorescent lamps in a backlight unit for a liquid crystal display that is dividedly driven.

As shown in FIG. 2, a backlight unit for a liquid crystal display according to an exemplary embodiment of the present invention includes a plurality of U-shaped fluorescent lamps 100, a printed circuit board 110, an insulator 120, and a first transformer 130. And a second transformer 131 and a connector 140.

The first electrode 101 and the second electrode 102 are formed at both ends of the U-shaped fluorescent lamp 100. Here, the U-shaped fluorescent lamp 100 is preferably configured of an external electrode fluorescent lamp. The external electrode fluorescent lamp is coated with a fluorescent material on the inner wall of the tube and filled with argon (Ar), neon (Ne), mercury (Hg) gas, etc., as a discharge gas in the inner space. An external electrode is installed outside of and an electric field is formed inside the tube by capacitive coupling between the external electrode and the outer wall of the tube to generate light by gas plasma discharge.

The printed circuit board 110 includes a first electrode line 111 for applying an alternating voltage to the first electrode 101 and a second electrode line 112 for applying an inverting alternating voltage to the second electrode 102. The first wiring 113 connecting the first electrode lines 111 and the second wiring 114 connecting the second electrode lines 112 are patterned to be spaced apart from each other.

The insulator 120 is provided on the printed circuit board 110, and is formed at a portion where the first electrode line 111 or the second electrode line 112 intersects the first wiring 113 or the second wiring 114.

The first transformer 130 is connected to the first wiring 113, and outputs an AC voltage to supply to the U-shaped fluorescent lamp 100, the second transformer 131 is connected to the second wiring 114, The inverted AC voltage is output and supplied to the U-shaped fluorescent lamp 100.

Here, the first electrodes 101 of each of the plurality of U-shaped fluorescent lamps 100 are disposed to be adjacent to each other, and the second electrodes 102 of each of the plurality of U-shaped fluorescent lamps 100 are disposed to be adjacent to each other. desirable. That is, when the first electrode 101 to which an alternating voltage is applied is represented by (+) and the second electrode 102 to which an inverting alternating voltage is applied to is represented by (−), a plurality of U-shaped fluorescent lamps 100 ), When the first electrode 101 and the second electrode 102 of each U-shaped fluorescent lamp 100 are shown in Fig. 2, (+), (-), (-), (+ ), (+), (-), (-), And (+) to form an arrangement. Through this arrangement, the same polarity may be applied to the adjacent electrodes, thereby reducing the influence between the adjacent electrodes and reducing the number of regions in which the insulator 140 is formed.

The printed circuit board 110 may further include a connector 140. By connecting the first electrode wire 101 or the second electrode wire 102 to the first wire 113 and the second wire 114 through the connector 140, connection or replacement of the circuit can be made easier. This reduces the risk of circuit breaks or short circuits.

According to the backlight unit for a liquid crystal display according to an exemplary embodiment of the present invention, an external electrode fluorescent lamp may be used as a U-shaped fluorescent lamp, and the U-shaped fluorescent lamps 100 constituting each unit block may be driven in parallel. Can be. Therefore, compared with the case of using a cold cathode fluorescent lamp as a U-shaped fluorescent lamp, the number of transformers can be reduced and thus the cost can be reduced.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. I can understand that. Therefore, since the embodiments described above are provided to fully inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The backlight unit for a liquid crystal display device according to the exemplary embodiment of the present invention configured as described above properly adjusts the crossing order of the electrode lines connected to the external electrode of the U-shaped fluorescent lamp, generates an AC voltage, and generates the AC voltage through the external electrode. By using the insulator in the inverter to be applied, it is possible to operate more stably by removing the adverse effect that may occur as the electrode wires are applied to the high voltage alternating voltage to cross or close.

Claims (6)

A plurality of U-shaped fluorescent lamps each having a first electrode and a second electrode formed at both ends thereof; A first electrode line for applying an alternating current voltage to the first electrode and a second electrode line for applying an inverting alternating voltage to the second electrode are configured, and the first wiring connecting the first electrode lines and the second electrode line are connected to each other. A printed circuit board patterned such that second wirings are spaced apart from each other; And And an insulator provided on the printed circuit board and formed at a portion where the first electrode line or the second electrode line intersects with the first wiring or the second wiring. The method of claim 1, And the plurality of U-shaped fluorescent lamps form a unit block for split driving. The method of claim 1, And the first electrode of each of the plurality of U-shaped fluorescent lamps is disposed adjacent to each other, and the second electrode of each of the plurality of U-shaped fluorescent lamps is disposed adjacent to each other. The method of claim 1, The printed circuit board further comprises a connector, wherein the first electrode line is connected to the first wiring through the connector. The method of claim 1, The printed circuit board further comprises a connector, wherein the second electrode line is connected to the second wiring through the connector. The method of claim 1, The printed circuit board is connected to a first wiring, a first transformer for outputting the AC voltage and supplying the U-shaped fluorescent lamp, and a second transformer connected to the second wiring, and outputting the inverted AC voltage to output the U-shaped fluorescent light. And a second transformer for supplying the lamp.

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