KR101308204B1 - Backlight inverter and driving method of the same, liquid crystal display having thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight inverter and a driving method thereof having improved lamp driving characteristics by minimizing the deviation of left and right tube currents of a lamp, and a liquid crystal display device having the same. The disclosed backlight inverter includes a plurality of lamps; A master inverter PCB and a slave inverter PCB supplying power to both ends of the plurality of lamps; A first balancer disposed between the plurality of lamp side electrode terminals and the master inverter PCB to adjust tube current; And a second balancer disposed between the plurality of lamp electrode terminals and the slave inverter PCB to adjust tube current, and on the master inverter PCB, a voltage to be applied to the lamp electrode electrode through the first balancer. And a first transformer, a second transformer for generating a voltage to be applied to the other electrode terminal of the lamp through the second balancer, and a main control IC for controlling the first transformer and the second transformer.

The present invention has the effect of reducing the size of the inverter by mounting all the components on one PCB.

LCD, Inverter, Lamp, Balancer, Tube Current, CCFL

Description

BACKLIGHT INVERTER AND DRIVING METHOD OF THE SAME, LIQUID CRYSTAL DISPLAY HAVING THEREOF}

1 is a view in which a backlight inverter PCB according to the related art is fastened to a rear cover bottom of a liquid crystal display.

2 is a view of the backlight inverter PCB according to the present invention is fastened to the bottom cover bottom of the liquid crystal display device.

3 is a view showing the structure of a backlight inverter according to the present invention.

4 is a diagram illustrating a structure of a backlight inverter having a balance capacitor attached thereto for controlling lamp tube current according to the present invention.

5 is a diagram illustrating a structure of a backlight inverter with a balanced transformer for controlling lamp tube current according to the present invention.

Description of the Related Art [0002]

150: lower cover 200a: master inverter PCB

200b: slave inverter PCB 201: first transformer

202: second transformer 231: first drive unit

232: second driver 250: main control IC

300a: first balancer 300b: second balancer

240: shutdown circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight inverter, a driving method thereof, and a liquid crystal display device having the same, which minimize lamp left and right tube current deviations to improve lamp driving characteristics.

CRT (Cathode Ray Tube), one of the commonly used display devices, is mainly used for monitors such as TVs, measuring devices, and information terminal devices.However, due to the weight and size of the CRT itself, Could not respond actively to demands.

Therefore, in the trend of miniaturization and weight reduction of various electronic products, CRT has a certain limit in weight and size, and is expected to replace the liquid crystal display (LCD) and gas using an electro-optic effect. Plasma display panels (PDPs) using discharge and EL display elements (ELDs) using electroluminescent effects are among them, and among them, researches on liquid crystal displays have been actively conducted.

In order to replace the CRT, a liquid crystal display device having advantages such as small size, light weight, and low power consumption has been actively developed, and recently, the liquid crystal display device has been developed enough to perform a role as a flat panel display device. In addition, the demand for the liquid crystal display device is continuously increasing as it is used for a monitor of a desktop computer and a large information display device.

Since most of the liquid crystal display devices are light-receiving devices that display an image by controlling the amount of light coming from the outside, a separate light source for irradiating light to the LCD panel, that is, a backlight unit is required. .

Generally, a backlight unit used as a light source of a liquid crystal display device is a method of disposing a cylindrical light emitting lamp, and is divided into an edge method and a direct method.

In the double edge type, a lamp unit is installed on the side of a light guide plate for guiding light. The lamp unit includes a lamp that emits light, a lamp holder that is inserted at both ends of the lamp to protect the lamp, And a lamp reflector that is fitted to the side surface of the light guide plate and reflects the light emitted from the lamp toward the light guide plate.

As such, the edge method in which the lamp unit is installed on the side of the light guide plate is mainly applied to a liquid crystal display device having a relatively small size, such as a monitor of a laptop computer and a desktop computer, and has good light uniformity and a long durability life. It is advantageous to thin the liquid crystal display device.

On the other hand, the direct type method has been developed mainly as the size of the liquid crystal display device has increased to 20 inches or more, and a plurality of lamps are arranged in a row on the lower surface of the diffuser plate to direct light directly to the front of the LCD panel. will be.

Such a direct method is mainly used in a large screen liquid crystal display device requiring high luminance because the light utilization efficiency is higher than that of the edge method.

1 is a view in which the inverter PCB according to the prior art is fastened to the bottom cover bottom of the LCD.

1, the master inverter PCB 30 for supplying power to the lamps on the back of the lower cover 10, the liquid crystal panel, the optical sheet and a plurality of lamps (not shown) disposed on the front and The slave inverter PCB 40 is disposed.

As described above, the master inverter PCB 30 and the slave inverter PCB 40 respectively supply high-voltage voltages having different phases to the lamps. EEFL (External Electrode Fluorescent Lamp) and CCFL (Cold Cathode Fluorescent Lamp).

Both electrodes of the lamps are connected in parallel to a power terminal for receiving a voltage from the master inverter PCB 30 and a power terminal for receiving a voltage from the slave inverter PCB 40 at predetermined intervals.

Between the master inverter PCB 30 and the slave inverter PCB 40 receives a gating synchronization signal from the main controller to simultaneously synchronize the voltage generated by the master inverter PCB 30 with the voltage generated by the slave inverter PCB 40. Let's do it. Therefore, a cable 45 for synchronizing voltages is connected between the master inverter PCB 30 and the slave inverter PCB 40.

The conventional inverter having the above structure has the following problems.

First, since the main controller and the inverter protection circuit is further mounted on the master inverter PCB 30, the size is larger than that of the slave inverter PCB 40, so that the master inverter PCB and the slave inverter PCB process at the time of mounting the PCB It must be processed by dualizing, and it is difficult to work or assembly process because it needs to be assembled separately when assembling the backlight unit.

Second, since the master inverter PCB 30 and the slave inverter PCB 40 are spaced apart, there is a limit in reducing the production cost because additional synchronization cable for sending and receiving signals is required.

Third, since the control board, the master inverter PCB 30 and the slave inverter PCB 40 occupy a high portion of the lower cover rear surface of the liquid crystal display, they are spatially limited in arranging a power supply on the set.

Fourth, the impedance characteristics of the lamps are different, but since the same voltage generated in the master inverter PCB 30 and the slave inverter PCB 40 is applied, there is a disadvantage in that the lamp tube current difference occurs and has a non-uniform brightness characteristic.

The present invention provides a backlight inverter and a driving method thereof that can form the components mounted on the slave inverter PCB integrally on the master inverter PCB, thereby reducing the size of the backlight inverter while reducing the cost of the components. There is this.

Another object of the present invention is to provide a backlight inverter and a method of driving the same, by arranging balancers for equalizing the lamp tube current at each electrode terminal of the lamps so that the lamps can realize uniform luminance characteristics when driving the backlight. There is this.

In addition, another object of the present invention is to provide a liquid crystal display device which improves screen quality when displaying an image by integrating components on a master inverter PCB and making lamp tube current uniform.

In order to achieve the above object, a backlight inverter according to the present invention,

A plurality of lamps;

A master inverter PCB and a slave inverter PCB supplying power to both ends of the plurality of lamps;

A first balancer disposed between the plurality of lamp side electrode terminals and the master inverter PCB to adjust tube current; And

And a second balancer disposed between the plurality of lamp electrode terminals and the slave inverter PCB to adjust tube current.

On the master inverter PCB, a first transformer to generate a voltage to be applied to the one electrode end of the lamp through the first balancer, a second transformer and a first transformer to generate a voltage to be applied to the other electrode end of the lamp through the second balancer. And a main control IC for controlling the transformer and the second transformer.

The backlight inverter driving method according to another embodiment of the present invention,

Providing a plurality of lamps;

Generating from the master inverter PCB voltages to be applied to both electrode ends of the plurality of lamps;

Supplying one of two voltages generated from the master inverter PCB to the plurality of lamp one electrode terminals through the master inverter PCB, and supplying the other voltage to the other electrode terminal through the slave inverter PCB;

Adjusting the lamp tube current to have the same value when applied to both electrode ends of the plurality of lamps; and

Driving the lamps such that the same current flows through the plurality of lamps.

According to another embodiment of the present invention,

A display panel;

A plurality of lamps;

A master inverter PCB and a slave inverter PCB supplying power to both ends of the plurality of lamps;

A first balancer disposed between the plurality of lamp side electrode terminals and the master inverter PCB to adjust tube current; And

And a second balancer disposed between the plurality of lamp electrode terminals and the slave inverter PCB to adjust tube current.

On the master inverter PCB, a first transformer to generate a voltage to be applied to the one electrode end of the lamp through the first balancer, a second transformer and a first transformer to generate a voltage to be applied to the other electrode end of the lamp through the second balancer. And a main control IC for controlling the transformer and the second transformer.

According to the present invention, components mounted on the slave inverter PCB may be integrally formed on the master inverter PCB, thereby reducing the size of the backlight inverter while reducing the cost of the components.

In addition, the present invention, by placing a balancer for equalizing the lamp tube current at each electrode end of the lamp, so that the lamp can implement a uniform brightness characteristics when driving the backlight.

In addition, the present invention improves screen quality when displaying images by integrating components on the master inverter PCB and making the lamp tube current uniform.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a diagram illustrating a backlight inverter PCB according to the present invention fastened to the bottom of a lower cover of a liquid crystal display, and FIG. 3 illustrates a structure of a backlight inverter according to the present invention.

2 and 3, a master inverter PCB 200a and a slave inverter PCB 200b are disposed on the rear surface of the lower cover 150 of the liquid crystal display device, respectively. The master inverter PCB 200a controls the first transformer 201 and the second transformer 202 and currents for applying current to the lamps 220 disposed inside the lower cover 150. A main control IC 250.

The slave inverter PCB 200b includes only a second balancer 200b for controlling tube current when applying current to the lamps.

In addition, the master inverter PCB 200a and the slave inverter PCB 200b may be configured to apply the voltage generated by the second transformer 202 provided in the master inverter PCB 200a to the slave inverter PCB 200b. The PCB is connected by a wire 110. The wire 110 functions to transfer a voltage generated from the master inverter PCB 200a to the slave inverter PCB 200b.

That is, the master inverter PCB 200a generates voltages to be applied to both ends of the lamps 220 by the operation of the mounted main control IC 250, and then directly from the master inverter PCB 200a. A voltage is applied to the lamps 220, and a portion of the lamp 220 is applied to the lamps 220 through the slave inverter PCB 200b through the wire 110.

Lamps used in the present invention are EEFL (External Electrode Fluorescent Lamp) having an external electrode or CCFL (Cold Cathode Fluorescent Lamp) having an internal electrode.

The structure of the backlight inverter according to the present invention is as follows.

As illustrated in FIG. 3, all components for applying tube current to both ends of the lamps 220 are mounted on the master inverter PCB 200a. The master inverter PCB 200a may include a first transformer 201 for applying a voltage to one end of the lamps 220 and a second transformer for applying a voltage to the other end of the lamps 220. 202, a first driver 231 electrically connected to the first transformer 201 to adjust a voltage to be generated in the first transformer 201, and electrically connected to the second transformer 202. It includes a second driver 232 for adjusting the voltage to be generated in the second transformer 202. Here, the first driver 231 and the second driver 232 may be configured as a switching element made of a field effect transistor (FET).

In addition, a main control IC 250 for controlling the first driver 231 and the second driver 232 in common is further included.

In addition, the first transformer 201 and the second transformer 202 are connected to the first feedback circuit 261 and the second feedback circuit 262, respectively, so that the first transformer 201 and the second transformer ( The main control IC 250 may always detect the voltage or current output from the 202. That is, the main control IC 250 determines whether the voltage sensed by the first feedback circuit 261 and the second feedback circuit 262 is higher or lower than the set reference voltage or is always set. Controls the range of voltages to be generated by the transformer.

In FIG. 3, the first feedback circuit 261 and the second feedback circuit 262 are separated from the main control IC 250, but in some cases, the feedback circuit 261 and the second feedback circuit are provided. 262 may be integrally formed inside the main control IC 250 to form a one chip.

In addition, a first balancer 300a is disposed between the output terminal of the first transformer 201 and one end of the lamps 220 to adjust the tube current flowing through the lamps 220. Similarly, a second balancer 300b is disposed between the other ends of the lamps 220 and the wire 110 connected to the second transformer 202 on the slave inverter PCB 200b. The tube current flowing through the lamps 220 is adjusted. The voltage (current) applied to the second balancer 300b is transmitted through the wire 110 connected to the second transformer 202 disposed on the master inverter PCB 200a.

Although not shown, 240 is a shutdown circuit, which protects the inverter by stopping the system operation when an external shock or a conductor contacts the backlight inverter.

In the present invention, the transformers mounted on the master inverter PCB and the slave inverter PCB, respectively, are all mounted on the master inverter PCB to reduce the cost of manufacturing the PCB.

In addition, the present invention simplifies the drive of the inverter to generate a voltage having two different phases applied to both ends of the lamp by controlling two transformers disposed on the master inverter PCB (200a) with a single control IC.

In addition, the present invention arranges the first and second balancer (300a, 300b) consisting of a capacitor or a small transformer in order to adjust the lamp tube current between the lamps 220 and each transformer terminal to uniform the lamps 220 One current was allowed to be applied. Therefore, in the present invention, since the tube current flowing through the lamps 220 has almost the same value, the luminance uniformity of all the lamps 220 is improved.

4 is a diagram illustrating a structure of a backlight inverter equipped with a balance capacitor for controlling tube current according to the present invention.

As shown in FIG. 4, on the rear surface of the lower cover 150, a first transformer 201 and a first transistor 201 disposed between the first transformer 201 and the first lamp electrode terminal 270a to adjust a tube current flowing through the lamp. The first inverter capacitor 200a, the second transformer 202, and the main control IC 250 are integrally formed with the master inverter PCB 200a and the second lamp electrode terminal 270b are connected to control the lamp tube current A slave inverter PCB 200b consisting of two balance capacitors 400b is disposed.

The second transformer 202 of the master inverter PCB 200a is connected to the second balance capacitors 400b of the slave inverter PCB 200b by a wire 110.

The first balance capacitors 400a are connected to the electrode terminals of the lamps 220 in a one-to-one correspondence, and the capacitance values of the capacitors have different values so that uniform tube current flows through all the lamps. Adjust so that This is because the lamps 220 have different impedance values due to the internal characteristics of the lamps 220, so that the same tube current may flow only when all the lamps 220 have the same impedance. Accordingly, the first balance capacitors 400a are designed to have capacitance values of different values such that the lamps 220 have the same impedance value.

Similarly, the second balance capacitors 400b are also connected to the electrode terminals of the lamps 220 in a one-to-one correspondence, and are designed to have different capacitance values so that uniform tube current flows through all the lamps 220. do.

As described above, in the present invention, the first transformer 201 and the second transformer 202 on the master inverter PCB 200a and all the driving parts and feedback circuits necessary for the master side and the slave side are formed as shown in FIG. Reduced manufacturing costs.

FIG. 5 is a diagram illustrating a structure of a backlight inverter equipped with a balance transformer for controlling tube current according to the present invention.

Since the same components as those in FIG. 4 use the same reference numerals, reference is made to FIG. 4 when not described.

As shown in FIG. 5, first balanced transformers 500a in which small transformers are connected in series are disposed between the first transformer 201 and the first lamp electrode terminal 270a of the master inverter PCB 200a.

The first balance transformers 500a are transformers having a coil end connected to the first lamp electrode end 270a and a coil end connected to the first transformer 201, and a coil connected to the first transformer 201. One end is formed in a structure connected in series.

This is because, when an arbitrary voltage is output from the first transformer 201, all of the coil stages connected in series have the same current value. As such, when the coils connected in series with the first transformer 201 have the same current value, the same current may be applied to the lamps by adjusting the winding ratio of the coil connected to the first lamp electrode terminal 270a. .

In the same principle, the second balance transformers 500b are disposed on the slave PCB 200b so that the same current value may be applied to the second lamp electrode terminal 270b. Therefore, the first balance transformers 500a and the second balance transformers 500b are designed to have different turns ratios so that the same tube current flows in each of the lamps 220.

In addition, although not illustrated in the drawings, optical sheets and a liquid crystal display panel are assembled inside the lower cover 150, thereby accommodating uniform luminance light sources of lamps driven by the backlight inverter, thereby improving image quality. have.

As described above, in the present invention, a balancer composed of a capacitor or a transformer is disposed so that a uniform current is supplied to each of the lamps while reducing manufacturing costs by mounting all the backlight inverter components on one PCB.

As described in detail above, the backlight inverter according to the present invention forms integrally the components mounted on the slave inverter PCB on the master inverter PCB, thereby reducing the size of the backlight inverter while reducing the cost of the components. It works.

In addition, the present invention, by arranging balancers for equalizing the lamp tube current at each electrode terminal of both lamps, there is an effect that the lamps can implement a uniform brightness characteristics when driving the backlight.

In addition, the present invention, by integrating the components on the master inverter PCB, by uniformizing the lamp tube current, there is an effect of improving the screen quality when displaying an image.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

A plurality of lamps; A master inverter PCB and a slave inverter PCB supplying power to both ends of the plurality of lamps; A first balancer disposed between the plurality of lamp side electrode terminals and the master inverter PCB to adjust tube current; And And a second balancer disposed between the plurality of lamp electrode terminals and the slave inverter PCB to adjust tube current. On the master inverter PCB, a first transformer to generate a voltage to be applied to the one electrode end of the lamp through the first balancer, a second transformer and a first transformer to generate a voltage to be applied to the other electrode end of the lamp through the second balancer. And a main control IC for controlling the transformer and the second transformer, And the first balancer and the second balancer are balance capacitors arranged to correspond to each of the plurality of lamp electrode terminals, and the balance capacitors are designed to have different values such that the lamps have the same impedance. The backlight inverter of claim 1, wherein the first balancer is formed on the master inverter PCB. The backlight inverter of claim 1, wherein the second balancer is integrally formed on the slave inverter PCB. The backlight inverter of claim 1, wherein the plurality of lamps are cold cathode ray tube lamps having internal electrodes. delete delete delete A plurality of lamps; A master inverter PCB and a slave inverter PCB supplying power to both ends of the plurality of lamps; A first balancer disposed between the plurality of lamp side electrode terminals and the master inverter PCB to adjust tube current; And And a second balancer disposed between the plurality of lamp electrode terminals and the slave inverter PCB to adjust tube current. On the master inverter PCB, a first transformer to generate a voltage to be applied to the one electrode end of the lamp through the first balancer, a second transformer and a first transformer to generate a voltage to be applied to the other electrode end of the lamp through the second balancer. And a main control IC for controlling the transformer and the second transformer, The first balancer and the second balancer are balance transformers arranged to correspond to each of the plurality of lamp electrode terminals, and the balance transformers are designed to have different turns ratios such that the tube current flowing through the lamps has the same value. Backlight inverter. delete A display panel; A plurality of lamps; A master inverter PCB and a slave inverter PCB supplying power to both ends of the plurality of lamps; A first balancer disposed between the plurality of lamp side electrode terminals and the master inverter PCB to adjust tube current; And And a second balancer disposed between the plurality of lamp electrode terminals and the slave inverter PCB to adjust tube current. On the master inverter PCB, a first transformer to generate a voltage to be applied to the one electrode end of the lamp through the first balancer, a second transformer and a first transformer to generate a voltage to be applied to the other electrode end of the lamp through the second balancer. And a main control IC for controlling the transformer and the second transformer, The first balancer and the second balancer are balance capacitors disposed to correspond to each of the plurality of lamp electrode terminals, and the balance capacitors are designed to have different values so that each lamp has the same impedance. .

Images