KR100606442B1 - Driving part of liquid crystal display and driving method thereof - Google Patents

Abstract

The present invention relates to a driving unit of a liquid crystal display device having a reduced area while forming the same number of gradation voltages as in the prior art. And data lines; A latch unit for sequentially sampling and storing image information under the control of the shift register unit and then simultaneously outputting the stored image information; A first gradation voltage section for dividing the power supply voltage into a plurality of gradation voltages and extracting a voltage range for the gradation of image information; A second gray voltage unit for detecting and outputting an optimal gray voltage for the gray level of the image information among a plurality of gray voltages divided by the voltage range extracted by the first gray voltage unit; And a digital-to-analog converter for converting image information applied from the latch unit into an analog signal, and adjusting the level by the gray voltage of the second gray voltage unit to apply to the data lines.

Voltage distribution, gradation, resistance, liquid crystal, voltage drop

Description

Driving part of liquid crystal display device and driving method thereof {LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF DRIVING THE SAME}

1 is a view showing a general liquid crystal display device.

2 is a diagram showing a configuration of a general gray voltage unit;

3 is a view showing a driving unit of a liquid crystal display according to the present invention.

Figure 4 is a view showing the first and second gray voltage section according to the present invention.

*** Description of the symbols for the main parts of the drawings ***

101: data driver 102: shift register

104: latch portion 105: P decoder

106: N decoder 107: multiplexer

108: output buffer section 140: first gradation voltage section

150: second gray voltage unit VCC: power supply voltage

CS11: control signal SS11: sampling signal

DATA: Image information POL11: Polarity control signal

SOE11: Source output enable signal SEL1: First selection information

SEL2: second selection information GV11: gradation voltage

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving unit of a liquid crystal display device and a driving method thereof. In particular, the present invention relates to a driving unit for a liquid crystal display device and a driving method thereof. The present invention relates to a driving unit of a liquid crystal display device having a reduced total area and a driving method thereof.

In today's information society, display is more important as a visual information transmission medium. In order to occupy a major position in the future, display needs to satisfy requirements such as low power consumption, thinning, light weight, and high quality.

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

A liquid crystal display device displays an image by using optical anisotropy of liquid crystal. Plasma display panels or electric fields are not only small in view of conventional CRTs, but also smaller than CRT tubes having the same average power consumption. Along with the emission display, it is recently attracting attention as a next generation display device.

In general, a liquid crystal display device is a flat panel display device in which a data signal according to image information is individually supplied to pixels arranged in a matrix form, and a desired image can be displayed by adjusting light transmittance of the pixels. to be.

The liquid crystal display device is bonded so that a thin film transistor array board and a color filter board facing each other have a predetermined cell-gap, and are bonded to the bonded cell-gap. Supply liquid to a liquid crystal panel manufactured by filling a liquid crystal layer, a driving unit for supplying various control signals, image information, and driving voltages to the liquid crystal panel, and a liquid crystal panel having a non-luminescent property. And a backlight unit for expressing image information.

In the thin film transistor array substrate, a plurality of gate lines arranged horizontally and a plurality of data lines arranged vertically intersect with each other, and pixels are defined in a plurality of regions that are divided and partitioned. The pixel includes a switching element electrically connected to the gate line and the data line, and a pixel electrode to which a voltage of image information applied from the data line is applied.

The color filter substrate is arranged with red, blue and green color filters displaying a color image by combining the light supplied from the backlight unit. Prevent light leakage. A common electrode is formed on the front surface of the color filter substrate, by applying a constant electric field to the liquid crystal layer by a voltage difference between the common voltage applied to the common electrode and the voltage of the image information applied to the pixel electrode of the thin film transistor array substrate. , To adjust the transmittance of light.

The driving unit is provided outside the liquid crystal panel, and the driving unit is electrically connected to the outer region of the liquid crystal panel to supply various signals to the liquid crystal panel.

Referring to the liquid crystal display as described above with reference to the accompanying drawings as follows.

1 is a view showing a general liquid crystal display device.

Referring to FIG. 1, a liquid crystal display includes a liquid crystal panel 10 in which a thin film transistor array substrate and a color filter substrate are opposed to each other; A timing controller 60 which receives image information and generates various control signals and driving voltages; A gray voltage unit 70 for forming a plurality of gray voltages; A data driver 30 receiving the image information, control signals, and driving voltages from the timing controller 60 and applying a gray voltage corresponding to the image information to the liquid crystal panel 10; The gate driver 20 receives the control signals and the driving voltages from the timing controller 60 and applies the gate low voltage or the gate high voltage to the liquid crystal panel 10.

In the liquid crystal panel 10, data lines DL1 to DLn arranged to be uniformly spaced apart in the vertical direction, and gate lines GL1 to GLm arranged to be uniformly spaced apart in the horizontal direction intersect with each other and have a predetermined pattern area. Partition them. These areas are defined as pixels. The data lines DL1 to DLn are electrically connected to the data driver 30, and the gate lines GL1 to GLm are electrically connected to the gate driver 20.

The timing controller 60 receives the image information to form a plurality of control signals and driving voltages, supplies the image information, control signals, and driving voltages to the data driver 30, and supplies the image information to the gate driver 20. Supply control signals and drive voltages.

The gray voltage unit 70 forms a plurality of gray voltages for expressing an image in several levels of brightness in the liquid crystal panel 10 and supplies the gray voltages to the data driver 30.

The gate driver 20 applies a gate low voltage to each gate line GL1 to GLm. When the gate high voltages are sequentially applied to the gate lines GL1 to GLm in units of one frame, the pixels connected to the corresponding gate lines GL1 to GLm are activated, and image information from the data driver 30 is used. Is applied to the pixels.

As described above, the data driver 30 receives image information, control signals, and driving voltages from the timing controller 60.

In recent years, image information in a digital form that can include a large amount of data, can easily process data, and can realize high image quality is mainly used. Such digital image information is also widely used for transferring data from a medium such as a video card or a digital video disc (DVD) to a liquid crystal display device. However, in order to drive the liquid crystal layer of the liquid crystal panel, digital image information including bits having two voltages of '0' and '1' must be converted into analog image information having various voltage levels. The digital-analog conversion is performed by the data driver 30.

The gray voltage unit 70 forms a plurality of gray voltages for generating electric fields of various sizes in the liquid crystal layer, and applies the gray voltages to the data driver 30, and the data driver 30 applies digital image information. The gradation voltage corresponding to the constituent bit values is applied to the data lines DL1 to DLn as analog image information.

As a method of forming the gray scale voltages in the gray voltage unit 70, a voltage division method using a plurality of resistors is generally used. That is, a resistance string form is formed in which a plurality of resistors are connected in series, and a power supply voltage is applied to one side of the resistance string to sequentially drop the voltage. In this way, different voltages are formed between the resistors.

The configuration in the gray voltage unit 70 as described above will be described with reference to the drawings.

2 is a diagram illustrating a configuration of a general gray voltage unit.

Referring to FIG. 2, the gray voltage unit includes a plurality of resistors R1 to Rn connected in series. That is, the plurality of resistors R1 to Rn are connected in series to each other to form a resistance string. A power supply voltage VCC is supplied to one side of the resistors R1 to Rn, and the other side of the resistors R1 to Rn is grounded.

The power supply voltage VCC is sequentially dropped through the respective resistors, and voltages having various levels are formed between the resistors. These voltages are referred to as gray voltages (V0 to Vn).

As described above, since the gray voltage unit sequentially drops the power supply voltage VCC by the resistors R1 to Rn connected in series, as the number of gray voltages to be formed increases, the resistors R1 to Rn ) Should also be added.

Recently, since more and more 8-bit image information is used in a liquid crystal display device to contain large-capacity high-definition image information, in order to generate more gray scale voltages, the number of resistors must be increased in response to the number of gray voltages. The area of the driver increases, thereby limiting the thickness and weight of the liquid crystal display device.

Accordingly, the present invention has been devised to solve the above-described problems, and an object of the present invention is to drive a liquid crystal display device and a driving unit configured to form the same number of gradation voltages as in the prior art even with a smaller area than before. To provide a method.

To achieve the above object of the present invention, a driving unit of a liquid crystal display device includes: gate lines and data lines arranged to be uniformly spaced apart vertically and horizontally on a substrate; A latch unit for sequentially sampling and storing image information under the control of the shift register unit and then simultaneously outputting the stored image information; A first gradation voltage section for dividing the power supply voltage into a plurality of gradation voltages and extracting a voltage range for the gradation of image information; A second gray voltage unit for detecting and outputting an optimal gray voltage for the gray level of the image information among a plurality of gray voltages divided by the voltage range extracted by the first gray voltage unit; And a digital-to-analog converter for converting the image information applied from the latch unit into an analog signal, and adjusting the level by the gray voltage of the second gray voltage unit to apply to the data lines.

The liquid crystal display device includes a liquid crystal panel in which the first and second substrates are bonded to each other so as to maintain a constant cell gap, and a liquid crystal layer is provided in the space between the cell gaps. Since the liquid crystal display does not emit light by itself, light is supplied to the liquid crystal panel to display an image by the transmittance of the liquid crystal layer.

Data lines and gate lines that are arranged at regular intervals in the vertical and horizontal directions are formed on the first substrate, and pixels are provided in regions where the data lines and the gate lines intersect. The pixel is a basic unit of an image display, and a plurality of pixels are arranged to form an image display unit. Each of the pixels is provided with a pixel electrode to apply a voltage of image information.

The second substrate is provided with green, blue, and red color filters to mix light passing through the second substrate to display various color images. Black matrices are wrapped around the color filters in a net form to prevent light leakage. In addition, a common electrode is formed on the front surface of the second substrate so that an electric field is applied to the liquid crystal layer by a voltage difference between a common voltage applied to the common electrode and a voltage of image information applied to the pixel electrode of the first substrate. It is to control the transmittance of.

The liquid crystal display device includes a driver for driving the liquid crystal panel, and the driver may be broadly divided into a data driver and a gate driver.

The gate driver sequentially applies a scan signal to the gate lines every frame, and the data driver applies image information to each data line in synchronization with the scan signal. The image information supplied to the data lines is applied to the pixel voltage of each pixel to form an electric field in the liquid crystal layer by a voltage difference from the common voltage of the common electrode formed on the second substrate as described above. As a result, the liquid crystal molecules of the liquid crystal layer corresponding to each pixel change the arrangement and allow light to pass according to the respective transmittances.

The data driver includes a digital-to-analog converter that converts externally applied digital image information into analog image information.

Referring to the accompanying drawings, the driving unit of the liquid crystal display device as described above is as follows.

3 is a view showing a driving unit of the liquid crystal display according to the present invention.

Referring to FIG. 3, the driving unit of the liquid crystal display device includes a shift register section 102 for sequentially outputting the sampling signal SS11 by the control signal CS11; A latch unit 104 for sequentially sampling and storing image information DATA by the sampling signal SS11 of the shift register unit 102 and simultaneously outputting the stored image information DATA; A digital-analog converter 109 for converting image information DATA received from the latch unit 104 into an analog signal; A first gradation voltage unit 140 for dividing the power supply voltage VCC to form a plurality of gradation voltages, and extracting a voltage range for the gradation of the image information DATA; A second gray voltage unit 150 that receives the voltage range extracted from the first gray voltage unit 140 and detects and outputs an optimal gray voltage for the image information DATA; The digital-analog converter 109 converts the image information DATA applied from the latch unit 104 into an analog signal and adjusts and outputs the level by the gray voltage detected by the second gray voltage unit 150. Wow; And an output buffer unit 108 that buffers and outputs the analog signal output from the digital-analog converter 109.

The shift register unit 102 receives control signals CS11 such as a source start pulse (SSP) and a source sampling clock (SSC) from a timing controller (not shown). The plurality of shift registers included in the shift register unit 102 sequentially shift the source start pulse SSP according to the source sampling clock SSC to output the sampling signal SS11.

The latch unit 104 sequentially receives and stores the image information DATA in predetermined units according to the sampling signal SS11 of the shift register 102. When the source output enable signal SOE11 is applied, the stored image information DATA is simultaneously output. In this way, the image information DATA simultaneously output by the source output enable signal SOE11 is applied to the digital-analog converter 109.

The first and second gray voltage units 140 and 150 form a plurality of gray voltages GV11 in response to the gray levels of the image information DATA, and the gray to gray voltages GV11 are converted into the digital-analog converter 109. To apply.

The first gray voltage unit 140 receives a power supply voltage VCC and divides the voltage to form a plurality of gray voltages. The first gradation voltage unit 140 receives the first selection information SEL1 and selects two gradation voltages among the gradation voltages according to the first selection information SEL1. To 150. That is, a constant voltage range is applied to the second gray voltage unit 150.

The second gray voltage unit 150 divides the voltage range applied from the first gray voltage unit 140 to form a plurality of gray voltages, and among the gray voltages according to the second selection information SEL2. One is selectively detected and applied to the digital-to-analog converter 109.

As described above, unlike the prior art in which a plurality of gray voltages are formed in one gray voltage unit, in the present invention, a plurality of gray voltages are generated through a plurality of gray voltage units, such as the first and second gray voltage units 140 and 150. Go through First, the first gradation voltage unit 140 divides the power supply voltage VCC at a predetermined voltage interval. The voltage interval can be set arbitrarily, but it is not necessary to set the voltage interval too subdivided. This is because any one of the plurality of voltage ranges formed in the first gray voltage unit 140 will be further subdivided in the second gray voltage unit 150.

The first gradation voltage unit 140 undergoes a first voltage dividing process, and one voltage range extracted according to the first selection information SEL1 is applied to the second gradation voltage unit 150. Since the second gray voltage unit 150 only needs to divide the applied voltage range into a plurality of gray voltages, a large number of resistors are not required as in the related art. The second gray voltage unit 150 divides the voltage range applied by the first gray voltage unit 140 at a small voltage interval. For example, when the voltage required for the grayscale of the image information DATA is 5.6V, the power supply voltage VCC is formed in the first grayscale voltage unit 140 in units of 1V, and 5V among the plurality of voltage ranges. A voltage range of ˜6 V is applied to the second gray voltage unit 150, and the second gray voltage unit 150 divides the voltage range of 5 V to 6 V at a voltage interval of 0.1 V. FIG. As such, 5.6V among the gray voltages divided by 0.1V intervals is detected as an optimal gray voltage and output to the digital-analog converter 109.

On the other hand, when a constant electric field is continuously applied to the liquid crystal layer of the liquid crystal display device, the liquid crystal deteriorates, and a phenomenon in which an afterimage occurs due to a DC voltage component occurs. Therefore, in order to prevent deterioration of the liquid crystal and to remove the DC voltage component, the voltage of the image information is applied to the positive and negative repetition based on the common voltage. This driving method is called an inversion method. Here, image information having a voltage higher than the common voltage will be referred to as positive image information, and image information having a voltage lower than the common voltage will be referred to as negative image information.

The inversion driving method includes a frame inversion method in which the polarity of the image information is inverted by one frame unit of the image, a line inversion method in which the polarity of the image information is inverted and supplied in the gate line unit, and image information. There is a dot inversion scheme in which polarities of P are inverted and supplied for each adjacent pixel and inverted in units of one frame of an image.

The digital-analog converter 109 processes the image information DATA into positive image information and negative image information in order to drive the liquid crystal display in an inversion manner. The digital-analog converter 109 includes a P decoder 105 for converting the image information DATA into positive image information, and an N decoder for converting the image information DATA into negative image information. 106, and a multiplexer 108 for selecting and outputting any one of the positive image information and the negative image information.

The image information DATA output from the latch unit 10 is supplied to both the P decoder 105 and the N decoder 106. The P decoder 105 and the N decoder 106 convert the image information DATA into a positive analog signal and a negative analog signal, respectively. However, since the positive analog signal and the negative analog signal are voltages that are insufficient to drive the liquid crystal display device, the second analog voltage unit 150 receives the second analog voltage unit 150 corresponding to the gray level of the image information DATA. The gray level voltage GV11 is mixed to raise the voltage level of each analog signal. As described above, the positive analog signal and the negative analog signal level adjusted by the gray scale voltage GV11 are applied to the multiplexer 107, and the multiplexer 107 receives the positive analog signal according to the polarity control signal POL11. Only one of a signal and a negative analog signal is applied to the output buffer unit 108. The output buffer 108 buffers an applied positive analog signal or negative analog signal to the data lines.

As described above, the first and second gray level voltage units 140 and 150 finally narrow the voltage range of the power supply voltage VCC through the voltage dividing process for the first and second stages to finally optimize the gray level of the image information. A gradation voltage is formed and output. The first and second gray voltage units 140 and 150 will be described in detail with reference to the accompanying drawings.

4 is a diagram illustrating first and second gray voltage units according to the present invention.

Referring to FIG. 4, the first gray voltage unit 240 includes a plurality of resistors R1 to Rk. The first gray voltage voltage G1V0 to G1Vn− is formed by sequentially lowering the power supply voltage VCC. A first partial pressure part forming 1); The first divided voltage G1V0 to G1Vn-2 is applied from the first voltage divider except for the first gray voltage G1Vn-1 of the highest gray level, and according to the first selection information SEL11, the first selection voltage SEL_GV1. A first multiplexer 242 for outputting a; The second divided voltage SEL_GV2 is output from the first voltage divider according to the first selection information SEL11 by receiving the first gray voltages G1V1 to G1Vn-1 except for the first gray voltage G1V0 of the lowest gray level. It consists of a second multiplexer 244.

The second gray voltage unit 250 includes a plurality of resistors R1 to Rj, and the first selected voltage SEL_GV1 and the second selected voltage SEL_GV2 applied from the first gray voltage unit 240. A second voltage dividing unit for dividing the voltage range therebetween to form a plurality of second gradation voltages G2V0 to G2Vm-1; And a third multiplexer 252 for receiving the second gray voltages G2V0 to G2Vm-1 from the second voltage divider and outputting a third selection voltage SEL_GV3 according to the second selection information SEL12. .

The first voltage divider is configured in the form of a resistance string in which a plurality of resistors R1 to Rk are connected in series, and receives a power supply voltage VCC to one side of the first voltage divider to receive the plurality of resistors R1 to Rk. The voltage drops sequentially. As such, the power supply voltage VCC is divided to form a plurality of first gray voltages G1V1 to G1Vn-1.

Two multiplexers 242 and 244 are provided in the first gray voltage unit 240, and the first gray voltages G1V1 to G1Vn-1 are applied from the first voltage divider.

The first multiplexer 242 is applied with the first gray voltages G1V0 to G1Vn-2 except for the highest gray voltage G1Vn-1 among the first gray voltages G1V1 to G1Vn-1, and the second multiplexer 242 is applied to the second multiplexer 242. The multiplexer 244 receives the first gray voltages G1V1 to G1Vn-1 except for the lowest gray voltage G1V0 among the first gray voltages G1V0 to G1Vn-1.

The first and second multiplexers 242 and 244 are provided with input pins P11 to P1n-1 and P21 to P2n-1, respectively, and have a first gray level through the input pins P11 to P1n-1 and P21 to P2n-1. Voltages G1V0 to G1Vn-1 are applied. However, the first gray voltages G1V0 to G1Vn-1 applied to the input pins P11 to P1n-1 of the first multiplexer 242 are input pins P21 to P2n of the second multiplexer 244, respectively. -1) are shifted by one gradation and applied. That is, the first gray voltage G1V1 applied to the second input pin P12 of the first multiplexer 242 is applied to the first input pin P21 of the second multiplexer 244. As such, the first gray voltages G1V0 to G1Vn-1 are shifted and applied to the first and second multiplexers 242 and 244, and the first selection information SEL11 is applied to the first and second multiplexers 242 and 244, respectively. Is approved.

The first selection information SEL11 uses upper bits of the image information. The number of higher bits to be used as the first selection information SEL11 may be determined according to the number of gray levels to be divided by the first gray voltage unit 240. For example, when the first gradation voltage unit 240 divides the power supply voltage VCC into eight gradation voltages, only 3 bits of the upper bits of the image information are applied as the first selection information SEL11. In this case, since 2 ³ = 8, it can correspond to eight gray voltages, respectively.

When the first selection information SEL11 is applied to the first and second multiplexers 242 and 244, the first gray level voltages G1V0 to G1Vn-1 applied to the Mth input pins of the first and second multiplexers 242 and 244, respectively. ) Is selected and output as the first selection voltage SEL_GV1 and the second selection voltage SEL_GV2. The first gray voltages G1V0 to G1Vn-1 applied to the Mth input pins of the first and second multiplexers 242 and 244 are different. That is, the first gray voltage G1V0 continuous to the first gray voltages G1V0 to G1Vn-1 applied to the M input pin of the first multiplexer 242 at the M input pin of the second multiplexer 244. G1Vn-1) is applied. If the power supply voltage VCC is divided in units of 1 V in the first voltage divider and 5V is applied to the M input pin of the first multiplexer 242, the M input pin of the second multiplexer 244 is applied. 6V is applied. Accordingly, the first and second multiplexers 242 and 244 select different first gray voltages G1V0 to G1Vn-1 according to the first selection signal SEL11.

As described above, the first selection voltage SEL_GV1 and the second selection voltage SEL_GV2 respectively selected and output from the first and second multiplexers 242 and 244 have a constant voltage range. That is, the first gray voltage unit 240 extracts a predetermined voltage range according to the first selection signal SEL11. The voltage range is a range including the magnitude of the gradation voltage to be supplied to the digital-analog converter corresponding to the gradation of the image information.

Meanwhile, the first and second selection voltages SEL_GV1 and SEL_GV2 extracted from the first gray voltage unit 240 are applied to both ends of the second voltage divider of the second gray voltage unit 244. Accordingly, the plurality of resistors R1 to Rj constituting the second voltage divider have a voltage range between the first and second selection voltages SEL_GV1 and SEL_GV2 as a plurality of second gray voltages G2V0 to G2Vm-1. Partial pressure. Like the first voltage dividing unit, the second voltage dividing unit is configured in the form of a resistance string in which a plurality of resistors R1 to Rj are connected in series, but has a resistance value smaller than that of the resistors constituting the first voltage dividing unit. Since it is composed of R1 to Rj, the voltage range between the first and second selection voltages SEL_GV1 and SEL_GV2 is minutely divided.

The second gray voltages G2V0 to G2Vm-1 are input to respective input pins P31 to P3m of the third multiplexer 252. The third multiplexer 252 detects one of the second gray voltages G2V0 to G2Vm-1 according to the second selection information SEL12, and converts the digital-analog to a final gray voltage GV21. Apply to wealth. Here, the second selection information SEL12 is the remaining bits of the image information excluding the upper bits of the image information applied to the first selection information SEL11. The first and second selection information SEL11 and SEL12 may appropriately divide all the bits of the image information.

The driving of the first and second gray voltage units 240 and 250 as described above is as follows.

In the related art, in order to form 100 gray scale voltages, 99 resistors have been configured in the form of a resistance string connected in series. However, according to the present invention, the first gray voltage unit 240 and the second gray voltage unit 250 may be formed of the same number of gray voltages as in the prior art by using only nine resistors each. That is, the power supply voltage VCC is divided by the first gray voltage unit 240, divided into ten gray voltages, and only one voltage range is extracted and applied to the second gray voltage unit 250. The second gray voltage unit 250 divides the voltage range applied from the first gray voltage unit 240 into ten gray voltages. In such a case, the number of resistors used in the present invention is only 18. Of course, the number of resistors used may vary slightly depending on the number of gray voltages shared by the first gray voltage unit 240 and the second gray voltage unit 250.

In the present invention, using a much smaller number of resistors than the conventional one extracts only one voltage range according to the first selection information SEL11 among the plurality of voltage ranges formed by dividing the voltage in the first gray voltage unit 240. This is because the second gradation voltage unit 250 undergoes a voltage dividing process. That is, in the related art, since all gray voltages including gray voltages which are not used each time are applied to apply one gray voltage to the digital-analog converter, the number of resistors used is large. However, in the present invention, since only the required voltage range is extracted from the first gray voltage unit 240 and applied to the second gray voltage unit 250, it is not necessary to perform the voltage dividing process for the remaining unnecessary voltage ranges. Therefore, the number of resistors used can be greatly reduced, thereby reducing the production cost. In addition, the area of the gradation voltage part can be made small, thereby making the liquid crystal display device thin and light.

Meanwhile, when the gray voltage unit is manufactured to have the same area as in the prior art, more gray voltages may be formed in the same area than in the prior art, thereby realizing more accurate images.

As described above, the gradation voltage generating unit according to the present invention uses the same number of gradation voltages as the conventional gradation voltage through the two-step voltage dividing process by the first gradation voltage unit and the second gradation voltage unit, and uses a smaller number of resistors than the conventional ones. Can reduce the production cost.

In addition, since a smaller number of resistors are used than in the related art, the gray scale voltage part can be manufactured in a smaller area than in the prior art, resulting in a thinner and lighter liquid crystal display device.

In addition, when the gray voltage unit is manufactured to have the same area as in the prior art, since a larger number of gray voltages can be formed than in the related art, a more accurate image can be realized.

Claims (7)

Gate lines and data lines arranged to be uniformly spaced apart longitudinally and horizontally on the substrate; A latch unit for sequentially sampling and storing image information under the control of the shift register unit and then simultaneously outputting the stored image information; A first voltage divider for dividing a power supply voltage into a plurality of gray voltages, and a first gray voltage except for the highest gray voltage among the first gray voltages, and receiving one first gray voltage according to first selection information; A first multiplexer for outputting a voltage and a second multiplexer for receiving one first gradation voltage as a second selection voltage according to first selection information by receiving a first gradation voltage except for the lowest gradation voltage among the first gradation voltages; A first gray voltage unit comprising a; A second voltage divider configured to divide the first and second selection voltages applied by the first gray voltage voltage to form a second gray voltage, and one second according to the second selection information by receiving the second gray voltage; A second gray voltage unit including a third multiplexer which outputs a gray voltage to the data line as a third selected voltage; And And a digital-to-analog converter for converting image information applied from the latch unit into an analog signal, and adjusting the level by the gray voltage of the second gray voltage unit to apply to the data lines. Drive of the device. delete delete The liquid crystal display driver of claim 1, wherein the first selection voltage and the second selection voltage are continuous first gradation voltages. A driving method of a liquid crystal display device in which data lines and gate lines are uniformly spaced apart vertically and horizontally on a substrate. Sampling the image information sequentially and then simultaneously outputting the stored image information; Dividing the power supply voltage into a plurality of gray voltages, and extracting a voltage range for grays of the image information according to the first selection information; Dividing the extracted voltage range into a plurality of gray voltages, and selectively outputting an optimal gray voltage for grays of image information according to second selection information; And And adjusting the image information converted into an analog signal by the optimal gray voltage to the data line. The method of claim 5, wherein the image information is used as the first selection information and the second selection information. 7. The method of claim 6, wherein at least one bit of higher bits of the image information is used as first selection information, and bits other than bits applied as the first selection information are used as second selection information. A method of driving a liquid crystal display device.

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