KR100770275B1 - Back light assembly and liquid crystal display device using thereof - Google Patents

Abstract

At the time of manufacture, the luminance deviation of each lamp was inevitably generated within the permissible range, but when at least two of them were driven at the same time, the lamp whose luminance deviation was corrected for each lamp and the backlight assembly with the lamp's mounting structure that were reasonably changed were used. A liquid crystal display device is disclosed. To this end, a discharge electrode is formed outside the lamp, and the discharge electrode is coupled to the conductive lamp socket in a fitting manner. Luminance deviation can be minimized when driving a plurality of lamps, each of which is manufactured to have luminance deviations at the same time, and the assembly process and assembly time required for replacing, repairing, and repairing lamps can be greatly shortened.

LCD, Cold Cathode Tube Lamp, Extra Electrode

Description

BACK LIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY DEVICE USING THEREOF}

1 is a conceptual diagram illustrating a relationship between a cold cathode ray tube type lamp and an inverter of a backlight assembly for a conventional liquid crystal display device.

FIG. 2 is a conceptual view illustrating that a screen is divided due to a problem of a backlight assembly for a conventional liquid crystal display.

3 is an exploded perspective view illustrating a liquid crystal display and a backlight assembly for a liquid crystal display according to an embodiment of the present invention.

4 is a cross-sectional view of a cold cathode ray tube lamp for luminance self-compensation according to an embodiment of the present invention.

5 is a conceptual diagram illustrating a relationship between a cold cathode ray tube lamp and an inverter of a backlight assembly for a liquid crystal display according to an exemplary embodiment of the present invention.

6 is a perspective view showing an embodiment of a lamp socket unit according to an embodiment of the present invention.

7 is a perspective view showing an embodiment of a lamp socket unit according to another embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of display devices, and more particularly, when a display of a liquid crystal display device is performed by light generated from a plurality of different lamps, at the time of fabrication, different lamps exhibit different luminance deviations in each lamp. When driving, it is possible to overcome the luminance deviation as well as to change the part to apply the power to the lamp having such characteristics to suit the structural characteristics of the lamp to improve the assembly performance, suppress assembly failure, and have a simple repair characteristics A backlight assembly and a liquid crystal display using the same.

Recently, with the development of the technology of the electric industry, the electronic industry and the semiconductor industry, the development of the information processing apparatus which can process a huge amount of data in a short time is progressing rapidly.

Such an information processing apparatus processes a data input by a user and stores the data in the form of an electrical signal. In order to recognize and utilize the processed result data, the information processing apparatus displays a display device displaying the result data in the form of a text or an image. in need.

The display device which plays such a role is implemented in various forms such as a CRT-type ray tube type display device, an organic electroluminescence device, and a liquid crystal display device.                         

Until now, a CRT type display apparatus for precisely scanning an electron onto a light emitting surface on which fluorescent material and color pixels are densely formed is used for a wide range of applications.

On the other hand, the organic electroluminescent device is formed by forming a red organic light emitting material, a green organic light emitting material and a blue organic light emitting material having a predetermined area between two electrodes in the form of a matrix, and then forming an electric field between the two sheets of electrodes. In order to perform the display with the light generated from the blue organic light emitting material, it is used as a small display device.

However, the CRT type display device has the advantage of having a large display screen and displaying the display at a high resolution, but has a disadvantage of being unsuitable as a portable display device due to its bulky and heavy weight.

In the case of organic electroluminescent devices, they are much smaller in volume and lighter than CRT display devices, but are difficult to realize a large display. Thus, small display devices such as display devices for mobile phones and small displays for home appliances are still available. Its disadvantage is that its use is limited to devices and the like.

The disadvantages of the CRT display device and the organic electroluminescent device can be overcome by the liquid crystal display device.

A liquid crystal display device displays a character or an image by individually controlling a liquid crystal having an optical characteristic in which light transmittance varies according to the intensity of an electric field in a very small area unit. Such a liquid crystal display device has a very small volume and weight compared to a CRT display device, and can implement a large display device as compared to an organic electroluminescent device.

However, since the CRT display device and the organic electroluminescent device can display without a separate light source, the liquid crystal display device does not generate light by itself, so unlike the CRT display device and the organic electroluminescent device, a light source, eg For example, it requires sunlight, room lighting, and artificial light sources.

In particular, an artificial light source is mainly used in the liquid crystal display because the liquid crystal display itself generates light in order to perform the display in the absence of sunlight or indoor illumination light.

The artificial light source preferably uses a surface light source that generates a uniform brightness over the entire display area. However, since it is very difficult to realize a surface light source having a uniform brightness, a cold cathode ray tube in the form of a line light source instead of the surface light source is used. Anticorrosive lamps or LEDs are used. Recently, a cold cathode ray tube lamp having a low power consumption and high brightness and generating white light close to natural light is mainly used.

When the display area of the liquid crystal display device was small or medium, the display of the liquid crystal display device was sufficient with only one cold cathode ray tube lamp.

However, as the size of the liquid crystal display device has gradually increased in size, it has become difficult to secure sufficient brightness over the entire display area of the liquid crystal display device using a single cold cathode ray tube type lamp. There is a need for a so-called "direct method" to be installed below the liquid crystal display panel.                         

However, when a cold cathode ray tube lamp is installed in such a manner as to directly display a liquid crystal display, various problems occur.

The first problem is that it is not possible to achieve uniform luminance across the display area. Such a problem occurs when a cold cathode ray tube lamp is driven by connecting at least two cold cathode ray tube lamps in parallel to one “inverter”.

Specifically, all cold cathode ray lamps are manufactured to have slightly different luminance within an acceptable range at the time of manufacture.

In this case, the term “different brightness” means that some cold cathode ray-type lamps are brighter within the acceptable range through better current than the reference value, and some cold cathode ray-type lamps are relatively dark within the permissible range because they do not pass current well than the reference value. Means that.

When two or more cold cathode ray tube lamps having different luminance are connected in parallel to one inverter 10 as shown in FIG. 1, theoretically, all cold cathode ray tube lamps 20, 30, 40,50) must all have the same current, but in reality it is not.

This is as if four conductors with different resistance values are connected in parallel and a constant current is applied to them, and more current flows through the low-resistance conductors and less current flows into the higher-resistance conductors. to be.

That is, any of the at least two cold cathode ray tube lamps 10, 20, 3, and 40 is made to have a relatively low resistance value, so that more current can be applied to the cold cathode ray tube lamps. As the density of ions and electrons inside the cathode ray tube lamp increases, the internal resistance of the cold cathode ray tube lamp becomes lower, and as the internal resistance decreases, more current is applied.

On the contrary, the cold cathode ray tube lamp, which is manufactured to have a relatively high resistance value at the time of manufacture, is applied with relatively less current, and as a result, the density of ions and electrons in the cold cathode ray tube lamp decreases, and thus the internal resistance of the cold cathode ray tube lamp is decreased. Becomes higher and the process of applying less current is repeated as the internal resistance becomes higher.

As a result, when a cold cathode ray lamp having a lower internal resistance and a cold cathode ray lamp having a higher internal resistance are connected in parallel to one inverter, the cold cathode ray lamp having a lower internal resistance gradually becomes brighter. In contrast, the cold cathode ray lamp, which gradually increases its internal resistance, becomes gradually darker.

As a result, as illustrated in FIG. 1 or 2, one display screen 60 is divided into a dark place (I, II) and a bright place (III, IV). That is, one display screen appears to be divided into I, II, III, and IV, which causes severe display performance deterioration.

In addition, two power supply lines 22 and 24 are required to drive the cold cathode ray tube type lamp. After the power supply lines 22 and 24 and the cold cathode ray tube lamp are connected, the connection site is often disconnected by external shock.                         

In addition, the cold cathode ray lamp is a consumable item that needs to be replaced after a predetermined time, for example, 10,000 hours, but the cold cathode ray lamp is replaced by a welding method. When the replacement time is increased.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to drive the plurality of cold cathode ray tube type lamps with one inverter so that the luminance variation between the lamps does not occur and the time required for assembling them. To provide a backlight assembly that shortens, prevents disconnection after assembly, and improves assembly.

Another object of the present invention is to provide a liquid crystal display device capable of high-performance display because no luminance deviation occurs between lamps.

The backlight assembly according to the present invention for realizing the object of the present invention includes a container, a lamp assembly and a light diffusing means. The storage container includes a bottom surface. The lamp assembly is housed in the receiving container, and includes at least two or more cold cathode ray tube lamps for luminance self-compensation, a lamp socket unit, and a power supply means. The cold cathode ray tube lamps for luminance self-compensation include electrodes formed at both ends of an outer surface of a sealed lamp tube in which a predetermined discharge gas is injected. The lamp socket unit contacts the electrodes to supply power to the cold cathode ray lamps for self-compensation and to fix the lamp sockets and the electrodes formed in a coupling groove seated on an outer circumferential surface of each electrode. And a conductive piece installed on the bottom surface to electrically connect the lampholders. The power supply means supplies the power to the lamp socket unit. The light diffusing means is installed on the upper surface of the lamp assembly via the storage container to diffuse the light generated from the lamp assembly.

In addition, the liquid crystal display device according to the present invention for realizing another object of the present invention includes a liquid crystal display panel assembly, a storage container and a backlight assembly. The liquid crystal display panel assembly controls the liquid crystal to adjust the light transmittance of the liquid crystal. The storage container accommodates the liquid crystal display panel and the backlight assembly and includes a bottom surface. The backlight assembly includes at least one brightness self-compensating cold cathode tube lamps, a lamp socket unit and a power supply. The luminance self-compensating cold cathode ray tube lamps are installed at a predetermined distance from one side of the liquid crystal display panel assembly and include electrodes formed on an outer surface of a lamp tube in which discharge occurs. The lamp socket unit is in contact with the electrodes to supply power to the luminance self-compensating cold cathode ray tube lamps and the lamp sockets formed of coupling grooves in which the outer circumferential surface of each electrode is seated and the luminance self-compensating cold cathode ray tube lamp. And a conductive piece installed on the bottom surface to fix them to the storage container and electrically connecting the lamp sockets. The power supply supplies the power to the lamp socket unit.

Hereinafter, a unique operation and effects of a backlight assembly and a liquid crystal display using the same according to an embodiment of the present invention will be described with reference to the accompanying drawings.

3 is a view illustrating a liquid crystal display having at least two cold cathode ray tube type lamps according to an embodiment of the present invention.

The LCD 500 according to the exemplary embodiment of the present invention generally includes a case (not shown), a top chassis 100, a liquid crystal display panel assembly 200, an intermediate chassis 300, and a backlight assembly 400. do.

The liquid crystal display panel assembly 200 is composed of the liquid crystal display panel 210 and the driving circuit devices 250, 260, 220, and 230 again.

The liquid crystal display panel 200 is composed of a TFT substrate 211, a liquid crystal (not shown) and a color filter substrate 213.

The TFT substrate 211 is again composed of a transparent substrate, a thin film transistor, a gate line, a data line, and a pixel electrode.

More specifically, a thin film transistor formed in a matrix form is formed on the transparent substrate. As described above, a gate line is commonly connected to gate electrodes of thin film transistors belonging to the same column among thin film transistors arranged in a matrix form.

Meanwhile, data lines are commonly connected to source electrodes (not shown) of thin film transistors belonging to the same row among the thin film transistors arranged in a matrix form.

On the other hand, the pixel electrode is formed of a transparent and conductive indium tin oxide material on the drain electrodes (not shown) of all the thin film transistors arranged in a matrix form.

The color filter substrate 213 is again superposed on the TFT substrate 211 having such a configuration.

In this case, the color filter substrate 213 includes an RGB pixel formed on the transparent substrate and a common electrode formed over the entire surface of the transparent substrate.

At this time, the RGB pixel is formed at a position opposite to each pixel electrode 213 formed on the TFT substrate 211.

In the TFT substrate 211 and the color filter substrate 213 having such a configuration, the liquid crystal is injected to a predetermined thickness between the pixel electrodes and the RGB pixels so as to be aligned so that the liquid crystal display panel 210 is manufactured.

In order for the liquid crystal display panel 210 to operate, the thin film transistors belonging to one row of the thin film transistors arranged in a matrix form by applying the gate signals to the corresponding gate lines while the data signals are individually applied to all the data lines. A power source corresponding to the data signal is applied to the pixel electrodes connected to the turned-on thin film transistors while being turned on.

As such, when power is applied to the pixel electrode, an electric field change is generated between the pixel electrode and the common electrode, and thus, the liquid crystal is changed in response to the electric field change.

In this case, if there is light that can pass through the liquid crystal, the light passes through the liquid crystal and then passes through the RGB pixel to express a predetermined color.

By repeating the above process for one frame, a desired image is displayed. To realize this, the gate printed circuit board 260 is installed on the gate line through the gate flexible printed circuit 230, and the data flexible on the data line. The data printed circuit board 250 is installed through the printed circuit 220.

The gate flexible printed circuit 230, the gate printed circuit board 260, the data flexible printed circuit 220, and the data printed circuit board 250 constitute the driving circuit device described above.

On the other hand, such a liquid crystal display panel assembly 200 only serves to precisely control the alignment angle of the liquid crystal, the liquid crystal display panel assembly 200 alone can not display any characters or images.

This means that the backlight assembly 400 for supplying light to the liquid crystal display panel assembly 200 is required in order to display characters or images from the liquid crystal display panel assembly 200.

The backlight assembly 400 again includes a diffusion plate 430, a diffusion sheet 440, a lamp assembly 460, a reflection plate 420, and a storage container 410.

The lamp assembly 460 is composed of a cold cathode ray tube lamp 462 for luminance self-compensation, a lamp socket unit 463, and an inverter 465 (see FIG. 5).

The cold cathode ray tube lamp 462 for luminance self-compensation has a luminance deviation due to manufacturing characteristics at the time of manufacture, but when a plurality of lamps having luminance variations are connected to one inverter 465 in a parallel manner, luminance variation with time passes. Becomes smaller gradually, so that all have the same luminance characteristic.

4, the self-compensating cold cathode ray tube lamp 462 is sealed while mercury and discharge gas are injected into the lamp tube 462a having a cylindrical shape.

At this time, it is important to have a luminance chef compensation function by not forming a discharge electrode inside the lamp tube 462a.

In order to implement this, the discharge electrodes 462b are formed on outer surfaces of both ends of the lamp tube 462a. The discharge electrode 462b may be made of a conductive metal or a transparent and conductive indium tin oxide material.

The formation of the discharge electrode 462b on the outer surface of the lamp tube 462a is due to the inherent operating characteristics of the cold cathode ray tube type lamp.                     

Specifically, referring to FIGS. 3 to 5, when AC power swinging to two discharge electrodes 462b is applied, discharge occurs inside the lamp tube 462a by the electric field difference, and thus, the lamp tube ( The interior of the 462a is in a plasma state.

That is, as the discharge gas dissociates, discharge gas ions, electrons, and neutrons are generated, among which discharge gas ions are attracted to the discharge electrode 462b having a negative polarity, and the electrons have a discharge electrode having a positive polarity ( 462b).

At this time, the electrons drawn to the (+) discharge electrode 462b does not immediately exit to the (+) discharge electrode but the flow of electrons is disturbed by the lamp tube 462a.

The extent to which the flow of electrons is disturbed is explained by comparing them with cold cathode tube lamps with a current flow greater than the reference value within the allowable range at the time of manufacture and cold cathode tube lamps with a current flow less than the reference value within the allowable range. do.

First, the electron density in the lamp tube is naturally higher than the electron density in the cold cathode tube lamp when the current flow is more than the reference in the cold cathode tube lamp is initially driven.

However, the higher the electron density, the more the current flow in the lamp tube is disturbed by the lamp tube acting as a dielectric, resulting in a progressively lower electron density.

On the other hand, the current density in the cold cathode ray tube lamps in which the current flow is lower than the reference value within the permissible range is lower than that in cold cathode ray tube lamps where the current flow is relatively less disturbed by the lamp tube acting as a dielectric. As a result, the electron density gradually increases.                     

As a result, when driving at least two cold cathode ray tube lamps manufactured to induce a current flow deviation at the time of manufacture with one inverter, a difference in luminance occurs in two cold cathode ray tube lamps at the beginning of driving.

However, after a predetermined time has elapsed, the luminance of the cold cathode ray tube lamp with high luminance is gradually lowered and the luminance of the cold cathode ray tube lamp with low luminance is relatively high.

As a result, after a predetermined time has elapsed, the luminance generated in the two cold cathode ray tube lamps in which the current flows at the time of manufacture are in equilibrium, that is, they have almost the same luminance.

As shown in FIG. 3 or FIG. 5, the plurality of luminance self-compensation cold cathode ray tube lamps 462 having the above characteristics are lamp sockets installed on the bottom surface of the storage container 410 that is a component of the backlight assembly 400. It is fitted to the unit 463.

The lamp socket unit 463 serves to apply power to the discharge electrode 462b of the cold cathode ray tube lamp 462 for luminance self-compensation and to fix the cold cathode ray tube lamp 462 for luminance self-compensation so as not to move. .

The lamp socket unit 463 may be manufactured in various forms in order to implement the two functions described above, but two embodiments of the lamp socket unit 463 are provided in the present invention.

This will be described with reference to FIG. 6 or 7.

The lamp socket unit 463 is comprised from the electrically conductive piece 463a and the lamp socket 463b and 463c in which at least one is formed in the electrically conductive piece 463a.

First, the lamp socket 463b shown in FIG. 6 is opened by elasticity when the discharge electrode 462b of the cold cathode ray tube lamp 462 for luminance self-compensation is inserted from the top to the bottom, and once, the discharge electrode 462b. ) Is a resilient conductive clip having a semi-circular shape so as to be in close contact with the discharge electrode 462b as well as to prevent separation of the discharge electrode 462b.

In the lamp socket 463c shown in FIG. 7, the width W of the cut portion of the conductive cylinder is laterally cut, that is, the concave semi-cylindrical shape is smaller than the diameter of the discharge electrode 462b. 463d). In this structure, when the discharge electrode 462b is fitted into the coupling groove 462d, it is forcibly opened by elasticity, and after the discharge electrode 462b is coupled, the coupling groove 463d is connected to the discharge electrode 462b. By tightening, the discharge electrode 462b is not randomly separated from the coupling groove 463d.

At least one lamp socket 463b and 463c is formed to correspond to the number of the cold cathode ray tube lamps 462 for luminance self-compensation to be mounted on the conductive piece 463a having a long strip shape.

Thereafter, the lamp socket unit 463 is mounted to one inverter 465 as shown in FIG. 5.

Unexplained reference numeral V ₁ is an input voltage applied to the first winding, V ₂ is an output voltage output from the second winding, N ₁ is the first winding number, and N ₂ is the second winding number.

At this time, the first winding number and the second winding number are controlled by the output voltage.

The light generated by each of the self-compensating cold cathode ray tube lamps 462 of the lamp assembly 460 having the above configuration has the same brightness, but when viewed throughout the display area, the cold cathode ray tube lamp and the brightness of the self-compensation cold cathode ray tube lamps are the same. The brightness is still uneven among cold cathode tube lamps for self-compensation.

In order to overcome this problem, a diffusion plate 430 and a diffusion sheet 440 are formed on the upper surface of the lamp assembly 460 to increase the uniformity of light.

That is, in the state in which the lamp assembly 460 is formed in the storage container 410, the diffusion container 410 and the diffusion sheet 440 are formed in the storage container 410, and the intermediate chassis 300 is formed in the storage container 410. Combined.

The liquid crystal display panel assembly 200, the intermediate chassis 300, and the storage container 410 are firmly formed by the top chassis 100 while the liquid crystal display panel assembly 200 is installed on the upper surface of the intermediate chassis 300. Combined.

Thereafter, the liquid crystal display device 500 is manufactured by being coupled to the top chassis 100, followed by a case (not shown).

According to the above description, the luminance gap between the lamps generated by using a plurality of cold cathode ray lamps for supplying light to the liquid crystal display panel is eliminated, as well as improvement in assembling and mounting time for mounting the lamps. It has a number of effects that can solve all the various problems that occur.                     

In the present invention, a so-called direct backlight assembly in which the cold cathode ray tube lamps are positioned below the liquid crystal display panel assembly is described as a preferred embodiment. However, at least two cold cathode ray tube lamps are provided on the side of the liquid crystal display panel. The present invention can also be sufficiently applied to a so-called "side edge type backlight assembly" which supplies light to a liquid crystal display panel assembly through a light guide plate or the like.

Those skilled in the art to which the present invention pertains can understand that the present invention can be variously modified and changed without departing from the spirit and scope of the present invention as set forth in the claims below. will be.

Claims (9)

A storage container including a bottom surface; At least two brightness self-compensation cold cathode tube lamps including electrodes formed at both ends of an outer surface of a lamp tube sealed in a state in which a predetermined discharge gas is injected, in contact with the electrodes The lamp sockets are formed on the bottom surface to fix the electrodes and the lamp sockets formed of a coupling groove seated on the outer circumferential surface of each electrode. A lamp assembly comprising a lamp socket unit including a conductive piece for electrically connecting the lamps, and a power supply means for supplying the power to the lamp socket unit; And And a light diffusing means disposed on an upper surface of the lamp assembly through the storage container to diffuse light generated from the lamp assembly. delete The method of claim 1, wherein each lampholder is The width of the coupling groove is narrowed toward the lamp tube from each electrode toward the lamp assembly is coupled to the lamp tube while being forcibly opened by the elasticity of the lamp socket. delete delete A liquid crystal display panel assembly which controls the liquid crystal to adjust the light transmittance of the liquid crystal; A storage container accommodating the liquid crystal display panel assembly and including a bottom surface; And Luminance self-compensation cold cathode ray tube lamps including at least one or more electrodes disposed on a surface spaced apart from one side of the liquid crystal display panel assembly and including electrodes formed on an outer surface of a lamp tube in which discharge occurs. And the lamp sockets formed of a coupling groove in which the outer circumferential surface of each electrode is seated and the luminance self-compensating cold cathode ray tube lamps are fixed to the housing. And a lamp socket unit including a conductive piece electrically connected to the lamp sockets, and a backlight assembly having a power supply unit for supplying power to the lamp socket unit. delete delete delete

Images