KR101097561B1 - Lamp for backlight and liquid crystal display device using thereof - Google Patents

Abstract

In the backlight fluorescent lamp of the present invention, a resistance is formed between the main electrode and the auxiliary electrode to lower initial discharge voltage, thereby minimizing electrode portions at both ends of the fluorescent lamp to maintain uniformity of brightness in the longitudinal direction of the fluorescent lamp, and to achieve high efficiency. In order to, the fluorescent material is applied therein and the glass tube in which the discharge gas is injected; External electrodes formed at both ends of the glass tube; An auxiliary electrode extending from the external electrode in a longitudinal direction along an outer circumferential surface of the glass tube; And a resistance formed between the external electrode and the auxiliary electrode.

Cold Cathode Fluorescent Lamp, External Electrode Fluorescent Lamp, Auxiliary Electrode, Resistance

Description

Backlight fluorescent lamp and liquid crystal display using the same {LAMP FOR BACKLIGHT AND LIQUID CRYSTAL DISPLAY DEVICE USING THEREOF}

1A and 1B schematically show a structure of a general cold cathode fluorescent lamp and a driving method thereof.

2A and 2B schematically show a structure of a general external electrode fluorescent lamp and a driving method thereof.

3 is a view schematically illustrating a structure of an external electrode fluorescent lamp in which an auxiliary electrode is formed.

4 is an exemplary view schematically showing a structure of an external electrode fluorescent lamp according to a first embodiment of the present invention.

5A is an exemplary view schematically showing a structure of a cold cathode fluorescent lamp according to a second embodiment of the present invention.

FIG. 5B is an exemplary view showing an enlarged electrode part of the cold cathode fluorescent lamp of FIG. 5A; FIG.

DESCRIPTION OF REFERENCE NUMERALS

140, 240A, 240B: fluorescent lamp 142: electrode

143,243: auxiliary electrode 241: external electrode                 

244: resistance

The present invention relates to a fluorescent lamp for a backlight, and more particularly, to a backlight fluorescent lamp capable of realizing high brightness and high efficiency in a large liquid crystal display device and a liquid crystal display device employing the same.

In today's information society, display is more important as a visual information transmission medium, and in order to gain a major position in the future, it is necessary to satisfy requirements such as low power consumption, thinness, light weight, and high definition.

The display itself has a cathode ray tube (CRT), an electroluminescent element (EL), a light emitting diode (LED), a vacuum fluorescence display (VFD), an electric field It can be divided into emission type such as Field Emission Display (FED), Plasma Display Panel (PDP), and non-emission type such as Liquid Crystal Display (LCD). .

A liquid crystal display device displays an image by using optical anisotropy of liquid crystal. Plasma display panel or electric field is not only small compared to screen tube of the same sized CRT with better visibility and average power consumption than the CRT. Along with the emission display, it is recently attracting attention as a next generation display device.                         

The liquid crystal used in the liquid crystal display device is not a light emitting material that emits light itself, but a light source that modulates the amount of light coming from the outside to display on the screen, so that a separate light source for irradiating light to the liquid crystal display panel That is, it needs a lamp unit.

BACKGROUND ART In general, a liquid crystal display device is a display device in which data signals according to image information are individually supplied to pixels arranged in a matrix form so that a desired image can be displayed by adjusting light transmittance of the pixels.

To this end, the liquid crystal display device is a liquid crystal display panel which largely injects liquid crystal between an array substrate and a color filter substrate to output an image, and is installed on a rear surface of the liquid crystal display panel to provide light over the entire surface of the panel. The backlight unit emits light and a plurality of case parts are fixed to and coupled to the liquid crystal display panel and the backlight unit.

In this case, a common electrode and a pixel electrode are formed on the liquid crystal display panel where the array substrate and the color filter substrate are bonded to each other to apply an electric field to the liquid crystal layer, and the data is applied to the pixel electrode while a voltage is applied to the common electrode. When the voltage of the signal is controlled, the liquid crystal of the liquid crystal layer rotates by dielectric anisotropy according to the electric field between the common electrode and the pixel electrode to transmit or block light for each pixel to display characters or images.

On the other hand, the function of the backlight unit is to make a flat light with uniform brightness from the fluorescent lamp used as the light source, the thickness and power consumption of the liquid crystal display device to improve the light utilization efficiency while taking how thin the thickness of the backlight unit It depends a lot on what you do.

The backlight unit includes a direct type in which a fluorescent lamp is disposed on a rear surface of the liquid crystal display panel so that light is transmitted directly to the front surface of the panel, and the fluorescent lamp is disposed on one or both sides of the liquid crystal display panel so that the light is disposed on a light guide plate. Guide plates, reflection sheets, and sheets are distinguished by an edge method that is reflected, diffused and collected through the sheets to be transmitted to the front of the panel.

The edge method has an advantage of easy fabrication, while the direct method has a relatively advantageous advantage for a large liquid crystal display with respect to high uniformity of light.

Meanwhile, as a fluorescent lamp used as a light source in the backlight unit, a cold cathode fluorescent lamp (CCFL) is mainly used.

By the way, the cold cathode fluorescent lamp is easy to apply to the backlight unit of the edge method, but has a disadvantage that it is not easy to apply to the backlight unit of the direct method. The cold-cathode fluorescent lamp adopts a method in which a silicon rubber is wrapped after soldering between the lamp electrode and the lamp wire, so that the direct backlight unit including several lamps is provided. This is because the application of the soldering and the protection by the silicon rubber for each lamp separately requires a lot of processing time, and the protection of the individual joints is practically difficult as the integrated lamp holder is applied.                         

Hereinafter, a cold cathode fluorescent lamp configured as described above will be described in detail with reference to the accompanying drawings.

1A and 1B schematically illustrate a structure of a general cold cathode fluorescent lamp and a driving method thereof.

As shown in the drawing, the cold cathode fluorescent lamp has a structure in which a high pressure is applied to the electrodes 41 across the fluorescent lamp 40A to increase to a starting voltage at which current can be conducted, and then stabilized when the temperature is higher. In order to produce this, AC must be applied and maintained.

As such, the situation is limited to only one fluorescent lamp 40A. Therefore, in the direct type backlight, there is a difficulty in that the number of fluorescent lamps 40A must be individually operated.

Therefore, the backlight unit to which the cold cathode fluorescent lamp is applied is mostly manufactured in an edge type. Accordingly, a lamp that is easily applied to a direct backlight unit has been developed, and an external electrode fluorescent lamp (EEFL) has been developed. Was proposed.

Hereinafter, the external electrode fluorescent lamp will be described in detail with reference to the accompanying drawings.

2A and 2B schematically illustrate a structure of a general external electrode fluorescent lamp and a driving method thereof.

As shown in the figure, unlike the structure of the cold cathode fluorescent lamp in which the electrode protrudes into both sides of the glass tube, the external electrode fluorescent lamp is formed by applying a conductor material to both ends of the fluorescent lamp 40B. Ions polarized by the external electrode 42 are gathered at both ends of the fluorescent lamp 40B, and light undergoes a process of adding ions again at the moment of zero crossing by high-pressure alternating current. It is a driving method.

At this time, since the external electrode 42 is not in the fluorescent lamp 40B, an equivalent circuit can be viewed as having a capacitor at both ends, so that the plurality of fluorescent lamps 40B can be driven in parallel. Accordingly, if only an inverter having a large capacity is provided, the inverter can be turned on with a simpler mechanical structure and inverter than the cold cathode fluorescent lamp.

However, in general, since external electrode fluorescent lamps obtain high luminance by driving a high frequency of several MHz, they have problems such as electromagnetic interference (EMI) low efficiency and high frequency power supply. In particular, since external electrode fluorescent lamps require a relatively high discharge voltage compared to cold cathode fluorescent lamps, the area of the electrode must be wider or longer. Therefore, the luminance tends to decrease at both ends of the electrode, which is a problem in terms of efficiency. Have

The optimal length of the external electrode for high brightness and high efficiency in the external electrode fluorescent lamp is related to the total length of the fluorescent lamp and the diameter of the fluorescent lamp. That is, when the length of the fluorescent lamp is longer, the length of the optimal external electrode also tends to be longer. As described above, the external electrode fluorescent lamp needs to have an external electrode long in order to realize high brightness and high efficiency. The external electrode area is a non-light emitting area, and a relatively non-light emitting area is wider than that of a cold cathode fluorescent lamp. The formed region is a dead zone having extremely low luminance, and thus a uniform luminance cannot be obtained in the entire fluorescent lamp.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a backlight fluorescent lamp capable of realizing high brightness and high efficiency by improving the structure of the fluorescent lamp and a liquid crystal display device employing the same.

Other objects and features of the present invention will be described in the configuration and claims of the invention described below.

In order to achieve the above object, the backlight fluorescent lamp of the present invention is a glass tube coated with a fluorescent material therein and discharge gas is injected, an external electrode formed on both ends of the glass tube, from the external electrode along the outer peripheral surface of the glass tube It includes an auxiliary electrode extending and formed in the longitudinal direction and a resistance formed between the external electrode and the auxiliary electrode.

In addition, another backlight fluorescent lamp of the present invention is a glass tube coated with a fluorescent material therein, the discharge gas is injected, the main electrode is formed in the glass tube, and connected to the outside through a lead wire, an auxiliary electrode extending from the main electrode and It includes a resistance formed between the main electrode and the auxiliary electrode.

In addition, the liquid crystal display device of the present invention includes a liquid crystal display panel, an electrode portion consisting of a main electrode and an auxiliary electrode, a resistance is formed between the main electrode and the auxiliary electrode to emit light of high brightness and high efficiency to the liquid crystal display panel. And a lamp housing positioned on a lower surface of the fluorescent lamp and surrounding the fluorescent lamp.

Hereinafter, a preferred embodiment of a backlight fluorescent lamp and a liquid crystal display device employing the same according to the present invention will be described in detail with reference to the accompanying drawings.

3 is an exemplary view schematically illustrating a structure of an external electrode fluorescent lamp in which an auxiliary electrode is formed.

As shown in the figure, a fluorescent material is applied and a discharge gas is injected into the discharge glass tube, and electrodes 142 and 143 are symmetrically formed at both ends of the glass tube. The electrode is composed of an external electrode 142 which is a main electrode formed to surround both ends of the glass tube, and an auxiliary electrode 143 extending in a semicircle in the longitudinal direction along the outer circumferential surface of the glass tube from the external electrode 142. do.

As described above, the liquid crystal display device requires a backlight unit as a non-emission type display, and as the liquid crystal display device becomes larger, the backlight unit must be enlarged and the fluorescent lamp to enter therein becomes longer.

As such, when the length of the fluorescent lamp 140 is longer, the external electrode 142 for discharging the fluorescent lamp 140 also needs to be lengthened, and the luminance is reduced by forming a non-light emitting area by the length of the external electrode 142. . However, the formation of the auxiliary electrode 143 makes it possible to minimize the area of the external electrode 142, that is, the length of the external electrode 142, and the auxiliary electrode 143 is formed at the bottom of the glass tube to emit light toward the top of the glass tube. Since light is emitted, the non-light emitting area can be reduced.

As a result of the formation of the auxiliary electrode, the luminance problem according to the general structure of the conventional external electrode fluorescent lamp is improved, but additional power consumption and discharge from the main electrode to the external electrode are not sequentially generated due to the formation of the auxiliary electrode, so that the efficiency of kitchen cooking is relatively high. There is a problem that comes out as low.

Hereinafter, a first embodiment of the present invention which solves the above problems by forming a resistance between the main electrode and the auxiliary electrode will be described in detail with reference to the drawings.

4 is an exemplary view schematically illustrating a structure of an external electrode fluorescent lamp according to a first exemplary embodiment of the present invention, and illustrates an external electrode fluorescent lamp having a predetermined resistance formed between the external electrode and the auxiliary electrode.

As shown in the figure, the external electrode fluorescent lamp 240A of the present embodiment is coated with a fluorescent material and a discharge gas is injected into the discharge glass tube, and the electrodes 242 and 243 are symmetrically formed at both ends of the glass tube. The electrode is composed of an external electrode 242 which is a main electrode formed to surround both ends of the glass tube, and an auxiliary electrode 243 extending in a semicircular shape along the outer circumferential surface of the glass tube from the external electrode 242. do.

In this case, a predetermined resistance 244 is formed between the external electrode 242 and the auxiliary electrode 243 in order to realize high efficiency and high brightness of the fluorescent lamp 240A. The resistor 244 is formed between the external electrode 242 and the auxiliary electrode 243, and serves to improve the efficiency of the fluorescent lamp 240A by turning off only the initial discharge from the auxiliary electrode 243. The shape and shape can be used in various ways. In particular, in order to increase the resistance 244, it may be formed in a spiral twisted structure.

Although not illustrated, a dielectric layer may be formed on the surface of the auxiliary electrode 243. The dielectric layer is formed for electrical leakage and safety. That is, when the external electrode fluorescent lamp 240A is used as a light source for a liquid crystal display device, when the external electrode 242 is combined in a form of being inserted into a connector for power connection, the auxiliary electrode 243 is exposed to the outside. If there is an electrical leakage and a safety problem, an insulating dielectric layer is formed.

The external electrode fluorescent lamp 240A is coated with a fluorescent material on a glass tube made of glass, and injected after a predetermined discharge gas is sealed. Thereafter, external electrodes 242, which are main electrodes, are formed at both ends of the glass tube.

At this time, the resistor 244 is installed along the external electrodes 242 at both ends, and the auxiliary electrodes 243 extending in a semicircular shape are formed.

As described above, when only the external electrode 242 is formed at both ends of the glass tube, as the length of the fluorescent lamp 240A becomes longer, the area of the electrode 242 is increased to decrease the emission area. By forming the auxiliary electrode 243 as described above, the area of the external electrodes 242 at both ends can be reduced.

In addition, by forming a resistor 244 between the external electrode 242 and the auxiliary electrode 243, the auxiliary electrode 243 is only the initial discharge, and the discharge is made by the external electrode 242 at both ends of the fluorescent lamp The efficiency of 240A can be improved.

That is, the initial discharge is discharged through the auxiliary electrode 243, and the discharge of the auxiliary electrode 243 is turned off due to the resistance 244, the discharge is changed to the kitchen discharge. Through this structure, the initial discharge voltage can be realized, and the area of the external electrode 242 can be reduced, and the pressure of the discharge gas can be increased or the length of the fluorescent lamp 240A can be increased.

For reference, the discharge has an edge effect (initial discharge) occurs in the first place, and when the charge (charge) there is discharged to the electrode located behind. However, there is a case in which the electrode behind the edge can not serve as the edge effect, in which the front electrode is used only for the initial discharge and turned off due to the formation of the resistance.

In addition, the pressure of the discharge gas is also important as a main factor of high brightness. That is, only a large amount of gas may be excited to have high luminance. At this time, if the gas pressure is high, the discharge is difficult to be made, and if the resistance is formed between the main electrode and the auxiliary electrode as shown in the present embodiment, the discharge voltage is lowered, so that the gas can be further injected, and thus a high brightness fluorescent lamp You will be able to create

It is not limited to the external electrode fluorescent lamp of the present invention, it is also applicable to the cold cathode fluorescent lamp in which the main electrode is formed in the glass tube, which will be described in detail through the following second embodiment.

FIG. 5A is an exemplary view schematically showing a structure of a cold cathode fluorescent lamp according to a second embodiment of the present invention, and FIG. 5B is an enlarged view of an electrode part of the cold cathode fluorescent lamp of FIG. 5A.                     

In this case, the fluorescent lamp of the present embodiment represents a cold cathode fluorescent lamp provided with a predetermined resistance between the electrode and the auxiliary electrode in order to implement high brightness and high efficiency.

As shown in the figure, the cold cathode fluorescent lamp 240B of the present embodiment is coated with a fluorescent material and discharge gas is injected into the discharge glass tube, and the electrodes 241 and 243 are symmetrically formed in the glass tube. The electrode is formed of a main electrode 241 formed inside the glass tube and connected to the outside through a lead wire and an auxiliary electrode 243 extending from the main electrode 241.

In this case, a predetermined resistor 244 is formed between the main electrode 241 and the auxiliary electrode 243 to realize high efficiency and high brightness of the fluorescent lamp 240B.

The cold cathode fluorescent lamp of the present embodiment configured as described above can be formed as follows.

The phosphor is coated in a glass tube made of glass, an electrode is inserted, and then a discharge gas is injected. Then, both ends of the electrode lead wire and the glass tube are sealed, and when the electrode is inserted, an electrode composed of a main electrode, an auxiliary electrode, and a resistor is inserted.

Hereinafter, a liquid crystal display device employing the above-mentioned fluorescent lamp for backlight of the present invention will be described by way of example.

The LCD includes a liquid crystal display panel in which pixels are arranged in a matrix form, a gate driving circuit unit and a data driver connected to a side surface of the liquid crystal display panel, and a backlight unit disposed on a rear surface of the liquid crystal display panel.                     

In this case, the liquid crystal display panel includes an array substrate and a color filter substrate bonded together so as to maintain a uniform cell gap, and a liquid crystal layer formed between the array substrate and the color filter substrate.

In addition, a common electrode and a pixel electrode are formed on the liquid crystal display panel where the array substrate and the color filter substrate are bonded to each other to apply an electric field to the liquid crystal layer, and to apply the data to the pixel electrode while a voltage is applied to the common electrode. When the voltage of the signal is controlled, the liquid crystal of the liquid crystal layer rotates by dielectric anisotropy according to the electric field between the common electrode and the pixel electrode to transmit or block light for each pixel to display characters or images.

In this case, in order to control the voltage of the data signal applied to the pixel electrode for each pixel, a switching element such as a thin film transistor (TFT) is individually provided in the pixels.

Meanwhile, the gate driving circuit unit and the data driving circuit unit are combined with the liquid crystal display panel in various forms to supply scan signals and image information to a plurality of gate lines and data lines formed in the liquid crystal display panel, thereby providing pixels of the liquid crystal display panel. Drive it.

Meanwhile, the backlight unit, that is, the reflective sheet, the light guide plate, the optical sheet, and the lamp assembly, are sequentially stacked and received by a mold frame.

In this case, the liquid crystal display panel and the backlight unit may be supported by a lower cover disposed on the rear surface of the backlight unit, and the lower cover may be coupled to the mold frame by a screw.

On the other hand, the lower cover and the mold frame may be coupled by a hook method for rapid assembly. That is, the lower cover and the mold frame may be coupled by forming an insertion groove in the lower cover and a hook in the mold frame to insert the hook of the mold frame into the insertion groove of the lower cover. The hook may be formed in the insert frame may be formed in the mold frame.

The upper edge of the mold frame coupled to the lower cover is compressed by the top case, and the top case may be coupled to the mold frame by a screw or hook method.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

As described above, the backlight fluorescent lamp according to the present invention provides an effect of maintaining uniformity of luminance in the longitudinal direction of the fluorescent lamp by minimizing electrode portions at both ends of the fluorescent lamp by forming an auxiliary electrode.

In addition, by forming a resistance between the main electrode and the auxiliary electrode can reduce the initial discharge voltage to increase the length of the fluorescent lamp, resulting in high brightness and high efficiency.

Claims (10)

A glass tube to which a fluorescent substance is applied and discharge gas is injected; External electrodes formed at both ends of the glass tube; An auxiliary electrode extending from the external electrode in a longitudinal direction along an outer circumferential surface of the glass tube; And Fluorescent lamp comprising a resistance formed between the external electrode and the auxiliary electrode. The fluorescent lamp of claim 1, wherein the auxiliary electrode is formed at the bottom of the glass tube in a semicircle to emit light toward the top of the glass tube. The fluorescent lamp of claim 1, further comprising a dielectric layer formed on a surface of the auxiliary electrode to insulate the auxiliary electrode. The fluorescent lamp of claim 1, wherein the resistance lowers the initial discharge voltage by switching discharge to the external electrode after the initial discharge of the auxiliary electrode. The fluorescent lamp of claim 1, wherein the auxiliary electrode increases the light emitting area of the glass tube by reducing the area of the external electrode. A glass tube to which a fluorescent substance is applied and discharge gas is injected; A main electrode formed in the glass tube and connected to the outside through a lead wire; An auxiliary electrode extending from the main electrode; And A fluorescent lamp comprising a resistance formed between the main electrode and the auxiliary electrode. 7. The fluorescent lamp of claim 6, wherein the resistance lowers the initial discharge voltage by switching discharge to the main electrode after the initial discharge of the auxiliary electrode. 7. The fluorescent lamp of claim 6, wherein the auxiliary electrode increases the light emitting area of the glass tube by reducing the area of the main electrode. 7. The fluorescent lamp according to claim 1 or 6, wherein the resistance has a spiral twisted structure. A liquid crystal display panel; A fluorescent lamp comprising an electrode part comprising a main electrode and an auxiliary electrode, wherein a resistance is formed between the main electrode and the auxiliary electrode to emit light of high brightness and high efficiency to the liquid crystal display panel; And And a lamp housing positioned on a lower surface of the fluorescent lamp and surrounding the fluorescent lamp.

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