KR20050049079A - Liquid crystal display - Google Patents

Abstract

The present invention relates to a liquid crystal display device capable of reducing the number of transformers on an inverter for driving a plurality of lamps.

According to an exemplary embodiment of the present invention, a 2N U-shaped lamp including first and second electrodes disposed side by side and formed at both edges of a glass tube, wherein N is a positive integer, and the 2N− And a plurality of connecting lines for connecting the first U-shaped lamp and the 2N-th U-shaped lamp.

The present invention can reduce the cost of the inverter due to the reduced number of transformers and can simplify the configuration of switching elements and circuit components of the inverter. In addition, the present invention can improve the workability for fastening between the inverter and the lamp by reducing the number of output connectors of the inverter.

Description

Liquid Crystal Display {LIQUID CRYSTAL DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of reducing the number of transformers on an inverter for driving a plurality of lamps.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be increasingly wider in application due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD displays the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the control switches arranged in a matrix form.

Since the LCD is not a self-luminous display device, a light source such as a back light unit is required. There are two kinds of LCD backlight units, a direct type type and an edge type type. The direct type diffuser diffuses light from N lamps arranged side by side on the back side of the diffuser plate to irradiate the liquid crystal panel. The light guide plate method irradiates the liquid crystal panel with light from a lamp irradiated through an incident surface provided on a side surface of the light guide plate using a transparent light guide plate.

Referring to FIG. 1, a conventional liquid crystal display device includes N lamps 12, in which N is a positive integer, disposed in parallel with the liquid crystal panel 6 to irradiate light to the liquid crystal panel 6. And a bottom cover 10 accommodating the N lamps 12, a diffusion plate 16 covering the front surface of the bottom cover 10, and optical sheets sequentially stacked on the diffusion plate 16. 18).

The liquid crystal panel 6 includes a spacer (not shown) for injecting liquid crystal between the upper substrate 3 and the lower substrate 5 and for maintaining a constant gap between the upper substrate 3 and the lower substrate 5. . In the upper substrate 3 of the liquid crystal panel 6, a color filter, a common electrode, a black matrix, and the like, which are not shown, are formed. In addition, signal lines such as data lines and gate lines (not shown) are formed on the lower substrate 5 of the liquid crystal panel 6, and thin film transistors are formed at the intersections of the data lines and the gate lines. The thin film transistor switches a data signal to be transmitted from the data line toward the liquid crystal cell in response to a scan signal (gate pulse) from the gate line. The pixel electrode is formed in the pixel region between the data line and the gate line. In addition, one side of the lower substrate 5 is formed with a pad region for connecting data lines and gate lines, respectively, and in this pad region, a tape in which a driver integrated circuit for applying a driving signal to the thin film transistor is mounted. A carrier package is attached. The tape carrier package supplies data signals and scan signals to the data lines and the gate lines from the driver integrated circuit, respectively.

The upper polarizing sheet (not shown) is attached to the upper substrate 3 of the liquid crystal panel 6, and the lower polarizing sheet (not shown) is attached to the rear surface of the lower substrate 5. At this time, the upper and lower polarizing sheets serve to extend the viewing angle of the image displayed by the liquid crystal cell matrix.

Each of the N lamps 12 uses a cold cathode fluorescent lamp, and each of the N lamps 12 includes a glass tube, inert gases inside the glass tube, and a high voltage electrode installed at both ends of the glass tube. ) And a low voltage electrode (Low). Inert gas is filled in the glass tube, and phosphor is coated on the inner wall of the glass tube.

Each of these N lamps 12 is driven by an AC waveform voltage of high voltage supplied from the inverter 30 as shown in FIG. To this end, the inverter 30 includes an inverter integrated circuit 40 for converting lamp driving power supplied from the power supply device into an AC waveform in response to a control signal from an external system (not shown), and from the inverter integrated circuit 40. N transformers 42 for converting AC waveforms into high voltage AC waveforms, and high voltage AC waveforms output from each of the N transformers 42 connected to each of the N lamps 12 through a wire. N output terminals 44 for supplying N to each of the N lamps 12.

The inverter integrated circuit 40 switches switching elements, not shown, in response to a control signal supplied from the system, converts the lamp driving power supplied from the power supply device into an AC waveform, and supplies them to each of the N transformers 42.

Each of the N transformers 42 converts an AC waveform supplied from the inverter integrated circuit 40 to the primary winding by a turns ratio of the primary winding and the secondary winding to an AC waveform of high voltage. Each of the high voltage AC waveforms generated by each of the N transformers 42 is supplied to each of the N output terminals 44. At this time, the number of N transformers 42 is equal to the number of N lamps 12.

Each of the N output terminals 44 is connected to the high voltage electrode High of each of the N lamps 12 through a wire. At this time, the high voltage electrode High of each of the N lamps 12 is disposed to be adjacent to the inverter substrate 30. Meanwhile, the low voltage electrode Low of each of the N lamps 12 is connected to the base voltage source GND and is connected to the inverter integrated circuit 40 via the feedback line FB. At this time, the inverter integrated circuit 40 detects the tube current of the N lamps 12 based on the feedback signal supplied through the feedback line FB and controls the switching elements to supply the N lamps 12. To control the tube current.

The bottom cover 10 is made of aluminum, and prevents light leakage of visible light emitted from each of the N lamps 12, and the front cover, that is, diffuser plate, which propagates visible light traveling to the side and the back of the N lamps 12. Reflecting toward 16 improves the efficiency of the light generated in the lamps 12.

The diffuser plate 16 allows the light emitted from the N lamps 12 to propagate toward the liquid crystal panel 6 and to be incident at a wide range of angles. Such a diffusion plate 16 uses a coating of a light diffusion member on both sides of a film made of a transparent resin.

The optical sheets 18 improve the efficiency of light emitted from the diffuser plate 16 to irradiate the liquid crystal panel 6.

Such a conventional LCD generates a uniform light by using N lamps 12 disposed on the bottom cover 10 and irradiates the liquid crystal panel 6 to display a desired image. However, such a conventional LCD uses a large number of lamps 12 to improve the efficiency and brightness of the light irradiated to the liquid crystal panel 6. Accordingly, the conventional LCD requires N transformers 42 equal to the number of N lamps 12. Therefore, in the conventional LCD, the number of parts of the lamp driving circuit including the switching elements and the circuit elements mounted on the inverter 30 to drive the N lamps 12 increases, thereby increasing the price of the inverter 30. The cost of LCD increases.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of reducing the number of transformers on an inverter for driving a plurality of lamps.

The present invention also relates to a liquid crystal display device capable of reducing the cost of the inverter by simplifying the circuit configuration of the inverter for driving a plurality of lamps.

In order to achieve the above object, the liquid crystal display according to the embodiment of the present invention is N (where N is a positive integer) N including first and second electrodes disposed side by side and formed on both edges of the glass tube. And a plurality of connection lines for connecting the 2N-th U-shaped lamp and the 2N-th U-shaped lamp.

In the liquid crystal display, each of the plurality of connection lines may interconnect the second electrode of the 2N-1 th U-shaped lamp and the first electrode of the 2N th U-shaped lamp.

In the liquid crystal display, each of the first and second electrodes is formed at any one of the inside and the outside of the glass tube.

The liquid crystal display includes a bottom cover for accommodating the 2N U-shaped lamps, a diffuser plate disposed on the bottom cover, a plurality of optical sheets stacked on the diffuser plate, and a plurality of optical sheets on the plurality of optical sheets. The liquid crystal panel may further include a liquid crystal panel disposed at each intersection of the data lines and the gate lines.

In the liquid crystal display, the 2N U-shaped lamps may be accommodated in the bottom cover to be parallel to the data lines.

The liquid crystal display may further include an inverter for supplying a high voltage AC waveform to the 2N lamps.

In the liquid crystal display device, the inverter includes an inverter integrated circuit for converting a lamp driving power source from the outside into an alternating current waveform using a switching element, and a 2N element for converting the alternating current waveform from the inverter integrated circuit into the high voltage alternating current waveform. And a transformer and an output terminal connected to each of the 2N transformers and connected to each of the 2N lamps through a wire.

In the liquid crystal display, the inverter supplies the high-voltage alternating current waveform having a first phase to a first electrode of the 2N-1 th U-shaped lamp, and a first phase to the second electrode of the 2N th U-shaped lamp. It is characterized by supplying a high-pressure AC waveform having a second phase different from the.

In the liquid crystal display, the first phase and the second phase have a phase difference of 180 degrees.

In the liquid crystal display, the inverter supplies the high voltage AC waveform having the first phase to the first electrode of the 2N-1 th U-shaped lamp and the first phase to the second electrode of the 2N th U-shaped lamp. Supplying the AC waveform of the high voltage having a second phase different from that of the second N-shaped lamp, and supplying the AC waveform of the high voltage having the second phase to the first electrode of the 2N + 1 th U-shaped lamp. The high voltage AC waveform having the first phase is supplied to the second electrode of the magnetic lamp.

In the liquid crystal display, the first phase and the second phase have a phase difference of 180 degrees.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 to 8.

Referring to FIG. 3, a liquid crystal display according to an exemplary embodiment of the present invention includes N liquid crystal panels 106 arranged in parallel with each other to irradiate light to the liquid crystal panel 106 (where N is a positive integer). 2N connecting lines 114 and 2N U-shaped lamps 112 for connecting U-shaped lamps 112 and two adjacent U-shaped lamps 112 among 2N U-shaped lamps 112. And a bottom cover 110 for receiving the light, a diffusion plate 116 covering the entire surface of the bottom cover 110, and optical sheets 118 sequentially stacked on the diffusion plate 116.

The liquid crystal panel 106 includes a spacer (not shown) for injecting liquid crystal between the upper substrate 103 and the lower substrate 105 to maintain a constant gap between the upper substrate 103 and the lower substrate 105. . The upper substrate 103 of the liquid crystal panel 106 is formed with a color filter, a common electrode, a black matrix, and the like, which are not shown. In addition, signal lines such as data lines and gate lines (not shown) are formed on the lower substrate 105 of the liquid crystal panel 106, and thin film transistors are formed at intersections of the data lines and the gate lines. The thin film transistor switches a data signal to be transmitted from the data line toward the liquid crystal cell in response to a scan signal (gate pulse) from the gate line. The pixel electrode is formed in the pixel region between the data line and the gate line. In addition, a pad region for connecting data lines and gate lines, respectively, is formed at one side of the lower substrate 105, and the pad region, in which a driver integrated circuit for applying a driving signal to the thin film transistor, is mounted. A carrier package is attached. The tape carrier package supplies data signals and scan signals to the data lines and the gate lines from the driver integrated circuit, respectively.

The upper polarizing sheet (not shown) is attached to the upper substrate 103 of the liquid crystal panel 106, and the lower polarizing sheet (not shown) is attached to the rear surface of the lower substrate 105. At this time, the upper and lower polarizing sheets serve to extend the viewing angle of the image displayed by the liquid crystal cell matrix.

The 2N U-shaped lamps 112 are composed of a glass tube, inert gases inside the glass tube, and first and second electrodes respectively installed at both ends of the glass tube. Inert gas is filled in the glass tube, and phosphor is coated on the inner wall of the glass tube. Specifically, as shown in FIG. 4, the first and second electrodes 120 and 122 of the 2N U-shaped lamps 112 installed at both ends of the glass tube are formed inside the glass tube, or illustrated in FIG. 5. As can be formed outside the glass tube. Accordingly, in the present invention, 2N U-shaped lamps 112 in which electrodes are installed in the glass tube will be described as an example.

The 2N connecting lines 114 connect two adjacent U-shaped lamps 112 among the 2N U-shaped lamps 112. In detail, each of the 2N connecting lines 114 connects the second electrode of the 2N-1st U-shaped lamps 112 and the first electrode of the 2Nth U-shaped lamps 112 to each other.

Each of the 2N U-shaped lamps 112 is driven by an AC waveform voltage of high voltage supplied from the inverter 130 as shown in FIG. 6. To this end, the inverter 130 from the inverter integrated circuit 140 and the inverter integrated circuit 140 for converting the lamp driving power supplied from the power supply device into an AC waveform in response to a control signal from an external system (not shown). 2N transformers 142 converting AC waveforms into high voltage AC waveforms, and high voltage AC waveforms output from each of the 2N transformers 142 connected to the 2N lamps 112 through wires. Is provided with 2N output terminals 144 for supplying to each of the 2N lamps 112.

The inverter integrated circuit 140 switches switching elements, not shown, in response to a control signal supplied from the system, converts the lamp driving power supplied from the power supply device into an AC waveform, and supplies them to each of the 2N transformers 142.

Each of the 2N transformers 142 converts the AC waveform supplied from the inverter integrated circuit 140 to the primary winding by the turns ratio of the primary winding and the secondary winding into an AC waveform of high voltage. Each of the high voltage AC waveforms generated by each of the 2N transformers 142 is supplied to each of the 2N output terminals 144. At this time, the phase of the high voltage AC waveform output from the 2N-1 th transformer 142 among the 2N transformers 142 is different from the high voltage AC waveform output from the 2N th transformer 142. That is, the phase of the high-voltage AC waveform output from each of the 2N-1th transformer 142 and the 2Nth transformer 142 has a phase difference of 180 degrees.

Each of the 2N output terminals 144 is connected to an electrode of each of the 2N U-shaped lamps 112 through a wire. At this time, the high voltage of each of the 2N U-shaped lamps 112 is disposed to be adjacent to the inverter substrate 130. The 2N output terminals 144 include terminals connected to the first electrodes of the 2N-1 < th > U-shaped lamps 112 and terminals connected to the second electrodes of the 2N < th > U-shaped lamps 112. do.

As such, the inverter 130 drives one U-shaped lamp 112 using one transformer 142. Specifically, the inverter 130 supplies a high-pressure alternating current waveform to the first electrodes of the 2N-1 < th > U-shaped lamps 112 interconnected by 2N connecting lines 114 as shown in FIG. The high voltage AC waveform is supplied to the second electrode of the 2N th U-shaped lamps 112. At this time, the high-voltage AC waveform supplied to the first electrodes of the 2N-1 < th > U-shaped lamps 112 has a positive polarity for one period P1, and the second electrode of the 2N-th U-shaped lamps 112 is oriented. The high-pressure AC waveform supplied to has reverse polarity during one cycle P1. Accordingly, the phase of the high-pressure AC waveform supplied to the first electrode of the 2N-1 < th > U-shaped lamps 112 and the second electrode of the 2N < th > U-shaped lamps 112 during one period P1 is 180 degrees. It will have a phase difference. Accordingly, each of the two U-shaped lamps 112 interconnected by the connecting line 114 is supplied from each of the electrodes 120 and 122 by receiving a high-voltage AC waveform having a phase difference of 180 degrees from each of the two transformers 142. As the current flows through the connection line 114 by the emitted electrons, energy is generated as the inert gas (Ar, Ne) is excited by the electrons, and the energy excites the mercury and emits ultraviolet rays. do. This ultraviolet light impinges on the luminescent phosphor applied to the inner wall of the glass tube to emit visible light.

The bottom cover 110 is made of aluminum, and prevents light leakage from visible light emitted from each of the 2N U-shaped lamps 112, and fronts the visible light traveling to the side and the back of the 2N U-shaped lamps 112. That is, by reflecting toward the diffuser plate 116, the efficiency of light generated in the lamps 112 is improved. At this time, the 2N U-shaped lamps 112 accommodated in the bottom cover 110 are disposed in the width direction of the bottom cover 110. That is, 2N U-shaped lamps 112 are disposed in the bottom cover 110 to be parallel to the data lines of the liquid crystal panel 106.

The diffuser plate 116 allows the light emitted from the 2N lamps 112 to propagate toward the liquid crystal panel 106 and allows incident light at a wide range of angles. Such a diffusion plate 116 uses a coating of a light diffusion member on both sides of a film made of a transparent resin.

The optical sheets 118 enhance the efficiency of light emitted from the diffuser plate 116 to irradiate the liquid crystal panel 106.

As described above, the LCD according to the embodiment of the present invention generates uniform light by using 2N U-shaped lamps 112 disposed on the bottom cover 110 to display a desired image by irradiating the liquid crystal panel 106. Done.

The LCD according to the embodiment of the present invention reduces the number of transformers 142 by interconnecting the connection lines 114 to the 2N-1 and 2N th U-shaped lamps 112 of the 2N U-shaped lamps 112. It can be reduced by half compared to the conventional. In addition, the present invention can reduce the number of lamps by half compared to the conventional by changing the conventional straight lamp to the U-shaped lamps (112). Accordingly, the present invention can simplify the circuit configuration of the inverter 130 by reducing the number of lamps 112 and the number of transformers 142 by half.

Meanwhile, the inverter 130 of the liquid crystal display according to another exemplary embodiment of the present invention has different phases at each electrode of one lamp 112 interconnected by the connecting line 114 as shown in FIG. 8. In addition to supplying a high-voltage AC waveform, the phase of the high-voltage AC waveform supplied to each electrode of the 2Nth (where N is a positive integer) lamp 112 interconnected by the connection line 114 is connected to the connection line 114. 2N-1st lamps 112 are connected to each other so as to be opposite to the phase of the high-voltage AC waveform supplied to the electrodes. Specifically, the high-pressure AC waveform supplied to the first electrode of the 2N-1 st lamp 112 interconnected by the connecting line 114 has a positive polarity for one period P1 and is supplied to the second electrode. AC waveform of has reverse polarity during one period (P1). On the other hand, the high-pressure alternating current waveform supplied to the first electrode of the 2Nth lamp 112 interconnected by the connecting line 114 has a reverse polarity during one period P1 and the high-pressure alternating current supplied to the second electrode. The waveform has positive polarity for one period P1. Therefore, each of the two U-shaped lamps 112 interconnected by the connecting line 114 is supplied with electrons emitted from each electrode by receiving a high voltage AC waveform having a phase difference of 180 degrees from each of the two transformers 142. As the current flows through the connection line 114 inside the glass tube, energy is generated as the inert gas (Ar. Ne) is excited by the electrons, and ultraviolet rays are emitted while the energy excites mercury. This ultraviolet light impinges on the luminescent phosphor applied to the inner wall of the glass tube to emit visible light.

According to another exemplary embodiment of the present invention, a liquid crystal display device includes a high voltage AC waveform supplied to the second electrode of the 2N-1 th lamp 112 and a high voltage AC waveform supplied to the first electrode of the 2N th lamp 112. By making the phases the same, the lamp mutual interference due to the output noise of the transformer 142 is essentially blocked, so that the lamp can be stably driven.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention includes a connection line for interconnecting 2N U-shaped lamps and electrodes of two adjacent U-shaped lamps. The present invention can reduce the cost of the inverter due to the reduced number of transformers and can simplify the configuration of switching elements and circuit components of the inverter. In addition, the present invention can improve the workability for fastening between the inverter and the lamp by reducing the number of output connectors of the inverter.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a cross-sectional view schematically showing a conventional liquid crystal display device.

FIG. 2 is a plan view showing an inverter for driving the lamp shown in FIG.

3 is a cross-sectional view schematically illustrating a liquid crystal display device according to an exemplary embodiment of the present invention.

4 is a plan view illustrating a plurality of U-shaped lamps shown in FIG. 3 with internal electrodes.

FIG. 5 is a plan view illustrating a plurality of U-shaped lamps shown in FIG. 3 having external electrodes. FIG.

6 is a plan view showing an inverter for driving the U-shaped lamp shown in FIG.

FIG. 7 is a diagram showing an AC waveform of high pressure supplied to the U-shaped lamp shown in FIG. 3; FIG.

8 is a view showing another form of the high-pressure AC waveform supplied to the U-shaped lamp shown in FIG.

<Description of Symbols for Main Parts of Drawings>

3, 103: upper substrate 5, 105: lower substrate

6, 106: liquid crystal panel 10, 110: bottom cover

12 lamp 16, 116 diffuser plate

18, 118: optical sheet 30, 130: inverter

40, 140: inverter integrated circuit 42, 142: transformer

44, 144: output terminal 114: connection line

120, 122: electrode

Claims (11)

2N U-shaped lamps (where N is a positive integer) including first and second electrodes arranged side by side and formed at both edges of the glass tube, And a plurality of connection lines for connecting the 2N-1 th U-shaped lamp and the 2N th U-shaped lamp. The method of claim 1, And each of the plurality of connection lines interconnects a second electrode of the 2N-1 th U-shaped lamp and a first electrode of the 2N th U-shaped lamp. The method of claim 1, And each of the first and second electrodes is formed at any one of the inside and the outside of the glass tube. The method of claim 1, A bottom cover to receive the 2N U-shaped lamps; A diffusion plate disposed on the bottom cover; A plurality of optical sheets stacked on the diffusion plate, And a liquid crystal panel disposed on the plurality of optical sheets and having a liquid crystal cell formed at each intersection of the data lines and the gate lines. The method of claim 4, wherein And the 2N U-shaped lamps are accommodated in the bottom cover to be parallel to the data lines. The method of claim 1, And an inverter for supplying a high voltage alternating current waveform to the 2N lamps. The method of claim 6, The inverter, An inverter integrated circuit which converts lamp driving power from the outside into an AC waveform using a switching element, 2N transformers for converting an AC waveform from the inverter integrated circuit into the AC voltage of the high voltage; And an output terminal connected to the 2N transformers and connected to each of the 2N lamps through a wire. The method of claim 6, The inverter, Supplying the high-voltage alternating current waveform having a first phase to a first electrode of the 2N-1 th U-shaped lamp, And a high voltage AC waveform having a second phase different from the first phase to the second electrode of the 2N th U-shaped lamp. The method of claim 8, And the first phase and the second phase have a phase difference of 180 degrees.  The method of claim 6, The inverter, Supplying the AC waveform of the high voltage having a first phase to a first electrode of the 2N-1 th U-shaped lamp, Supplying the high voltage AC waveform having a second phase different from a first phase to a second electrode of the 2N th U-shaped lamp, Supplying the high-voltage AC waveform having the second phase to a first electrode of the 2N + 1 th U-shaped lamp, And the high voltage AC waveform having the first phase is supplied to a second electrode of the 2N + 2 th U-shaped lamp. The method of claim 10, And the first phase and the second phase have a phase difference of 180 degrees.