KR20080030191A - Display device - Google Patents

Abstract

A display apparatus is provided to enhance the efficiency of a power supply unit by reducing voltage converting steps in comparison with conventional converting methods. A display apparatus includes a voltage supply unit(100), a backlight unit(300), a voltage converting unit(200), a data driver and a gate driver(500), and a display panel(600). The voltage supply unit generates a first driving voltage. The backlight unit generates beams in response to the first driving voltage. The voltage converting unit receives the first driving voltage and generates second, third, and fourth driving voltages. The data driver generates a data signal in response to the second driving voltage. The gate driver receives the third and fourth driving voltages, and generates gate signals. The display panel receives the beams from the backlight unit and displays images in response to the data and gate signals.

Description

 Display {DISPLAY DEVICE}

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1 is a block diagram illustrating a power conversion step in a general display device.

2 is a block diagram illustrating a display device according to an exemplary embodiment of the present invention.

3 is a block diagram illustrating a configuration of the voltage converter illustrated in FIG. 2.

4 is a diagram illustrating a circuit configuration of the first voltage converter illustrated in FIG. 3.

FIG. 5 is a diagram illustrating a circuit configuration of the second voltage converter illustrated in FIG. 3.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a display device capable of converting a power supply voltage from the outside into an internal power supply voltage.

In general, the liquid crystal display device receives module power from the outside, and the input module power is changed to an internal power supply voltage of a different level through various steps, and is provided to respective devices provided inside the liquid crystal display device.

1 is a block diagram illustrating a power conversion step in a general liquid crystal display device.

Referring to FIG. 1, a 3.3V power source corresponding to a module power source is applied to the DC-DC inverter 10 from the outside (power supply). The DC-DC inverter 10 forms an AVDD voltage in response to 3.3 V of the module power supply. Output voltages from the DC-DC inverter 10 are input to the first and second pumping circuits 12 and 14, respectively, to generate a gate on voltage and a gate off voltage. In this case, each of the first and second pumping circuits includes three or more stages of charge pumping circuits.

As described above, in the conventional liquid crystal display device, since power is received from the outside and changed into a different level of power through several steps, the efficiency of the power is lowered. In addition, in generating the gate on / off voltage, two or more three-stage charge pumping circuits are required. This complicates the circuit itself. Therefore, the efficiency of the total power consumption of the liquid crystal display device is lowered.

Accordingly, an object of the present invention is to provide a display device capable of reducing the overall power consumption.

The display device of the present invention for achieving the above technical problem includes a voltage supply unit, a backlight unit, a voltage converter, a data driver, a gate driver and a display panel. The voltage supply unit generates a first driving voltage. The backlight unit generates light in response to the first driving voltage. The voltage converter receives the first driving voltage and generates a second driving voltage, a third driving voltage, and a fourth driving voltage having different levels. The data driver generates a data signal in response to the second driving voltage provided from the voltage converter. The gate driver receives a third driving voltage and the fourth driving voltage from the voltage converter and generates a gate signal, respectively. The display panel receives light from the backlight unit and displays an image in response to the data signal and the gate signal.

The magnitude of the third driving voltage is twice the magnitude of the first driving voltage, and the fourth driving voltage is the same as the magnitude of the first driving voltage and is a voltage whose polarity is inverted with respect to the first driving voltage. .

According to the display device described above, the step of voltage conversion used in the display device can be reduced. In addition, by using the first driving voltage provided to the DC-AC inverter, the number of pumping of the pumping circuit can be reduced. As a result, the overall cost of the display device is reduced.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings. In understanding the drawings, it should be noted that like parts are intended to be represented by the same reference numerals as much as possible. In addition, in the following description, numerous specific details, such as specific processing flows, are described to provide a more general understanding of the invention. Incidentally, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. As a display device according to an exemplary embodiment of the present invention, a liquid crystal display device having a liquid crystal display panel will be described as an example. However, the technical idea proposed by the present invention is not limited to the liquid crystal display device.

2 is a block diagram illustrating a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the liquid crystal display device 700 according to an exemplary embodiment of the present invention may include a voltage supply unit 100, a voltage converter 200, a backlight unit 300, drivers 400 and 500, and a display panel ( 600).

The voltage supply unit 100 includes an AC input unit 110 and an AC-DC rectifier 120. The AC input unit 110 provides a general AC voltage of 100 to 240 volts directly into the liquid crystal display. In general, a predetermined plug may be plugged in to an outlet to output a general-purpose AC voltage to the inside of the display device 700.

The AC-DC rectifier 120 has a power factor correction (PFC) function to change a general-purpose AC voltage in the range of 100 to 240 volts into a DC voltage, and convert the changed DC voltage ('first driving voltage VIN') into a voltage. The converter 200 and the backlight unit 300 are respectively provided. The AC-DC rectifier 120 may be implemented through a diode rectifier, a pulse width modulation (PWM) rectifier, or an active PWM rectifier.

In the present invention, unlike the prior art, the gate driver 500 and the data driver 400 are driven by using a driving voltage (first driving voltage VIN) for driving the DC-AC inverter included in the backlight unit 300. Each power supply voltage is generated. That is, conventionally, a 3.3V power supply was input to generate various power supply voltages.

Meanwhile, in the present invention, the drive voltage of the gate driver and the drive voltage of the data driver are generated using an inverter drive voltage of 12 volts (first drive voltage).

In the liquid crystal display device 100 of the present invention, the changed DC voltage (hereinafter referred to as a first driving voltage) drives both the driving units 400 and 500 and the backlight unit (specifically, the DC-AC inverter 310). It should be noted that it is used as a driving voltage.

The voltage converting unit 200 receives the first driving voltage VIN from the AC-DC rectifying unit 120 of the voltage supplying unit 100 and has a second driving voltage AVDD and a third level having different levels. The driving voltage VON and the fourth driving voltage VOFF are generated.

3 is a block diagram illustrating a configuration of the voltage converter 200 illustrated in FIG. 2.

Referring to FIG. 3, the voltage converter 200 includes a first voltage converter 230, a second voltage converter 250, and a third voltage converter 270.

The first voltage converter 230 receives the first driving voltage VIN from the voltage supply unit 100, specifically, the AC-DC rectifying unit 120, and decompresses and outputs the second driving voltage AVDD. . The first driving voltage VIN is a DC-AC inverter driving voltage of about 12 volts, and the second driving voltage is a driving voltage driving the data driving unit of about 7.8 volts.

The second voltage converter 250 receives the first driving voltage VIN and boosts and outputs the voltage to the third driving voltage. In this case, the third driving voltage is a gate-on voltage VON provided to the liquid crystal display panel, and a voltage of 23 V is typically used.

The third voltage converter 270 receives the first driving voltage VIN and generates a fourth driving voltage VOFF. At this time, the fourth driving voltage VOFF is the first driving voltage VIN. It has the same magnitude as that of VIN and the polarity of the first driving voltage VIN is inverted. Here, the fourth driving voltage VOFF is a gate-off voltage VOFF, and a voltage of approximately -12 volts is used.

4 is a diagram illustrating an internal circuit of the first voltage converter 230 shown in FIG. 3.

Referring to FIG. 4, the first voltage converter 230 includes an input capacitor C1, a DC converter 234, a voltage divider 236, and a switch 232.

The input capacitor C1 is used to provide a stabilized input voltage VIN, that is, a first driving voltage VIN.

The DC converter 234 includes an inductor L1, a diode D1, and an output capacitor C2.

The inductor L1 is used to store energy of the input signal.

The diode D1 is 'turned off' by reverse bias or 'turned on' by forward bias according to the switching operation of the switching terminal SW of the switching unit 232 and is output from the switching unit 232. Emits a current corresponding to the voltage.

The diode D1 may be, for example, a schottky diode for performing a fast switching operation.

The output capacitor C2 is used to provide the stabilized output voltage VOUT, that is, the second driving voltage AVDD.

The voltage divider 236 includes a plurality of resistors R1 and R2 to divide the voltage output from the diode D1 based on the resistors R1 and R2 to generate a feedback signal Vfb. . The feedback signal Vfb is provided to the switching unit 232 to adjust the second driving voltage AVDD which is an output voltage. In the exemplary embodiment of the present invention, the voltage divider is configured using two resistance elements, but may vary according to the level of voltages required by the display device.

The switching unit 232 may be formed of one integrated circuit including an input terminal IN, a switching terminal SW, a feedback terminal FB, and a ground terminal GND.

The first driving voltage VIN is applied to the inside of the switching unit 232 to output a voltage reduced by a predetermined level through the input terminal IN.

One end of the switching terminal SW is connected to the other end of the inductor L1, and the other end thereof is connected to a switching element formed inside or outside the switching 232. According to a switching operation of the switching element, a current corresponding to a pulse signal output from the switching unit 232 is charged to the inductor L1 or discharged to the diode D1 through the switching terminal SW. The feedback signal Vfb provided from the voltage divider 236 is input through the feedback terminal FB. The ground terminal GND is connected to a ground voltage.

In summary, the present invention includes a first voltage converter 230 having a simple circuit configuration as described above. And, instead of receiving a separate voltage from the voltage supply unit 100, about 7.8 volts reduced to a predetermined level by using the existing first driving voltage VIN of about 12 volts provided to the DC-AC inverter 310. Generate a second driving voltage of.

Therefore, by generating the second driving voltage using a relatively large voltage of 12 volts input to the inverter 310, there is an effect of reducing the current consumption in the display device, and consequently the overall power consumption.

 FIG. 5 is a diagram illustrating an internal circuit of the second voltage converter 250 illustrated in FIG. 3.

As illustrated in FIG. 5, the second voltage converter 250 includes two charging pumping circuits for boosting the first driving voltage to the third driving voltage VON. The charging pumping circuit shown in FIG. 5 is also called a Dickson charge pumping circuit.

The second voltage converter 250 includes two diodes M1 and M2 connected in series, and two capacitors connected in parallel to the two diodes. In detail, an input terminal of the diode M1 of one stage is connected to the input pad 252 to receive a first driving voltage VIN through the input pad.

The two-stage diode M2 has a structure in which its input terminal is connected to the output terminal of the first-stage diode M1 so that the first-stage diode M1 and the two-stage diode M2 are connected in series.

One end of the first capacitor C1 is connected to the output terminal of the diode M1 of the first stage, and a pumping clock having a first phase from an external oscillator (not shown) through the other end of the first capacitor C1. VP1) is input. Here, the diode uses a MOS transistor that can be connected to the gate terminal and one terminal in common, it is an input terminal, that is, a cathode terminal, and the other terminal can be configured as an output terminal, an anode terminal.

One end of a second capacitor C2 is connected to an output terminal of the second stage diode M2 and has a phase opposite to the first phase from the external oscillator through the other end of the second capacitor C2. A pumping clock VP2 having two phases is input.

Hereinafter, the operation of the above-described two-stage charge pumping circuit will be described in detail.

The magnitudes of the predetermined pumping clock pulses VP1 and VP2 supplied from the external oscillator are set equal to the first driving voltage VIN, and have a phase difference of 180 degrees from each other. As shown in FIG. 5, since the MOS transistors M1 to M2 act as diodes, the charge increases in only one direction.

MOS transistors M1 and M2 operatively connected with a diode and capacitors C1 and C2 connected between a connection point of these transistors and a pumping clock input terminal. If the charge pump made by the combination of one MOS transistor M1 and one capacitor C1 is defined as a unit charge pump, the charge pump circuit shown in FIG. 5 may be referred to as a two-stage charge pump. .

The first pumping clock VP1 is supplied to the first capacitor C1 and the second clock signal VP2 is supplied to the second capacitor C2. According to the first pumping clock VP1, the voltage of the N1 node is increased to a constant voltage level by charge sharing of the first capacitor. In addition, the voltage of the N2 node is increased to a constant voltage level higher than the voltage of the N1 node by charge sharing of the second capacitor. The pumping operation by this method outputs the first input voltage, that is, the third driving voltage VON corresponding to twice (two stages) the first driving voltage VIN.

In this manner, the number of stages of the charge pump can be reduced by using the drive voltage of the inverter having a relatively high voltage input to the charge pump, that is, the first drive voltage.

Referring to FIG. 3 again, as described above, the third voltage converter 270 receives the first driving voltage VIN to generate a fourth driving voltage VOFF. In this case, the fourth driving voltage VOFF is generated. The voltage VOFF has the same magnitude as that of the first driving voltage VIN and has a polarity in which the polarity of the first driving voltage VIN is inverted.

The third voltage converter 270 does not change the magnitude of the first driving voltage, but outputs the fourth driving voltage VOFF having the inverted polarity of the polarity of the first driving voltage.

In this manner, the fourth driving voltage can be simply generated by providing an inverting circuit which inverts only its polarity to a negative polarity without changing the magnitude of the first driving voltage of 12 volts. Thus, as in the prior art, a separate charge pumping circuit for generating the gate off voltage VOFF is not required.

On the other hand, the inverting circuit provided in the third voltage converter 270 can be fully understood if one of ordinary skill in the art. Therefore, detailed description thereof will be omitted.

Subsequently, referring again to FIG. 2, the backlight unit 300 includes a DC-AC inverter 310 and a lamp 320. The DC-AC inverter 310 receives the first driving voltage VIN provided from the voltage supply unit, converts the AC voltage, and provides the converted AC voltage to the lamps 320. The lamp 320 receives the converted AC voltage and irradiates light onto the liquid crystal display panel 600.

The lamp 320 is generally composed of a predetermined fluorescent lamp disposed on the rear side of the LCD panel, and adjusts the output light level of the fluorescent lamp based on the current voltage provided from the DC-AC inverter 310 to adjust the liquid crystal display panel. Investigate on the back.

The drivers 400 and 500 include a data driver 400 and a gate driver 500. The data driver 400 generates a data signal in response to the second driving voltage AVDD provided from the voltage converter 200, specifically, the second voltage converter 250. In detail, the data driver 400 gamma-corrects an image signal for display based on a gamma voltage provided from a gamma voltage generator (not shown) operated by the second driving voltage AVDD, and performs gamma correction. The image signal is output to the liquid crystal display panel 600.

The gate driver 500 receives the third driving voltage VON and the fourth driving voltage VOFF provided from the voltage converter 200 to generate gate signals VON / VOFF, respectively. Here, the gate signal includes a gate on signal VON and a gate off signal VOFF.

In detail, the gate driver 500 receives the third driving voltage VON boosted by the second voltage converter 250 to generate the gate-on signal VON. In addition, the gate driver 500 inputs a fourth driving voltage VOFF having a second phase having a phase inverted with respect to the first phase of the first driving voltage by the third voltage converter 270. Receive. As such, the gate on / off (VON / VOFF) generated by the gate driver 500 is sequentially output to the liquid crystal display panel 600.

The liquid crystal display panel 600 crosses the plurality of gate lines that transmit the gate on / off signals provided from the gate driver 500 and the gate lines that transmit the data signals provided from the data driver 400. And a plurality of pixels formed in a matrix formed in a plurality of data lines and a region surrounded by the gate line and the data line, and each having a switching element (not shown) connected to the gate line and the data line.

In driving, when a gate on signal is applied to the gate line and the switching element is turned on, a data signal supplied to the data line is applied to each pixel electrode through the switching element. Then, an electric field corresponding to the difference between the pixel voltage applied to the pixel electrode and the common electrode voltage provided from the common electrode voltage generator (not shown) is applied to the liquid crystal capacitor so that light transmits at a transmittance corresponding to the intensity of the electric field. Therefore, an image is displayed.

According to the present invention as described above, since the voltage conversion step can be reduced than the conventional power conversion step, the efficiency of the power supply unit can be increased. In addition, since the first driving voltage provided to the DC-AC inverter is used, the number of pumping in the pumping circuit can be reduced. Thus, the overall power consumption of the display device is reduced.

As described above, the optimum embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (7)

A voltage supply unit generating a first driving voltage; A backlight unit generating light in response to the first driving voltage; A voltage converter configured to receive the first driving voltage and generate a second driving voltage, a third driving voltage, and a fourth driving voltage having different levels; A data driver generating a data signal in response to the second driving voltage provided from the voltage converter; A gate driver configured to receive a third driving voltage and the fourth driving voltage from the voltage converter and generate a gate signal, respectively; And And a display panel configured to receive light from the backlight unit and display an image in response to the data signal and the gate signal. The display device of claim 1, wherein the third driving voltage is twice the magnitude of the first driving voltage. The display device of claim 1, wherein the fourth driving voltage is equal to a magnitude of the first driving voltage and is a voltage whose polarity is inverted with respect to the first driving voltage. The method of claim 1, wherein the voltage converter, A first voltage converter configured to receive the first driving voltage and reduce the voltage to a second driving voltage; A second voltage converter configured to receive the first driving voltage and boost the voltage to a third driving voltage; And And a third voltage converter configured to receive the first driving voltage and generate a fourth driving voltage whose polarity is inverted with respect to the first driving voltage. The method of claim 4, wherein the first voltage converter A pulse width modulation signal generator generating the first pulse signal having a variable amplitude based on a feedback signal, and generating a second pulse signal by leveling down the first pulse signal; A direct current voltage converter configured to control the second pulse signal to be converted into the second driving voltage; And a voltage divider configured to generate the feedback signal by dividing the second driving voltage output from the DC voltage converter. The display device of claim 4, wherein the second voltage converter comprises a two-stage charging pumping circuit. The method of claim 2, wherein the second voltage converter A first stage diode receiving the first driving voltage; Two stage diodes connected in series with the one stage diode; A first capacitor connected to an output terminal of the diode of the first stage and receiving a pumping clock having a first phase from an external oscillator and applied to the output terminal of the diode of the first stage; And A second capacitor connected to an output terminal of the second stage diode and receiving a pumping clock having a second phase having a phase opposite to the first phase from the external oscillator to apply to the output terminal of the second stage diode; Display device characterized in that.

Images