KR100915634B1 - Apparatus for gray-scale voltage generator of flat display using gray-scale Digital Analog Converter - Google Patents

Abstract

The present invention relates to a gradation voltage DAC for minimizing an area occupied in a flat panel display and to generate a gradation voltage with low power consumption, and a flat display gradation voltage driving device using the same.

A voltage generator configured to generate at least one reference voltage, at least one bit gray level voltage control signal corresponding to at least one reference voltage generated by the voltage generator and at least one predetermined input signal; A first switch unit positioned whenever a digital analog control signal generating unit and a resistor string in which a plurality of resistors are connected in series and a total resistance value sequentially added up from the resistance values of the initial resistance of the resistor string become the first resistance values. And a second switch unit which is located from the point where the first switch unit is connected and is positioned whenever the total resistance value becomes the second resistance value, and a third switch which is positioned whenever the number of switches of the second switch unit is a predetermined number. And a first switch unit, a second switch unit, and a third switch unit in accordance with the gray voltage control signal generated by the digital analog control signal generator. According to an embodiment of the present disclosure, a flat display gray voltage driving device including a gray voltage generator configured to generate a gray voltage may be provided.

Description

Flat display gray scale voltage driving device {Apparatus for gray-scale voltage generator of flat display using gray-scale Digital Analog Converter}

The present invention relates to a gray voltage DAC and a flat panel gray voltage driving device using the same. In particular, the present invention relates to a gray scale voltage DAC using a thin film transistor using a thin film transistor as a resistor string and reducing the number of switches to minimize power consumption and an area occupied, and a flat panel display gray scale voltage driving device using the same.

The present invention is derived from a study conducted as part of the IT source technology development project of the Ministry of Information and Communication [Task management number: 2006-S-079-02, Task name: Smart window using a transparent electronic device]

In order to distinguish gray-scale in a flat panel display structure, a gray scale voltage driving device using a gray scale voltage digital analog converter (DAC: digital to analog converter, hereinafter referred to as a DAC) capable of accurately transmitting minute voltage differences to a display panel is required. It was.

1 is a diagram schematically illustrating a conventional gray voltage DAC compared with the present invention. In the figure, reference numeral 100 denotes a resistor-string type gray voltage DAC, reference numeral 110 denotes a capacitor type gray voltage DAC, reference numeral 120 denotes a ramp type gray voltage Represents a DAC.

In the case of the resistor string type 100, the gray scale voltage is determined by the resistor string 101 on the left side. In this case, the voltage is determined by selecting a part of the resistor strings 101 connected in series according to a signal generated from the decoder. Since the method, the voltage control switch 103 has a disadvantage that occupies a very large volume. In addition, a large amount of static current flows through the resistance column 101, which leads to a large power consumption.

In addition, the capacitor type 110 also has a disadvantage in that a large number of capacitors must be integrated in order to achieve high gray levels, thereby increasing the area of the circuit. In particular, since the capacitor type 110 needs to use an analog buffer, the image quality may be degraded due to the output difference between channels. In addition, there is a problem that it is difficult to generate an accurate gray scale voltage when capacitance mismatch occurs due to process variation. It was.

Lastly, in the case of the ramp signal type 120, the gray scale voltage can be selected using a circuit having the smallest area, but in practice, it is very difficult to uniformly transmit the ramp signal to each channel due to the RC delay phenomenon. Therefore, there is a disadvantage in that it is difficult to actually generate an accurate gray voltage.

Therefore, there has been a need for a gray voltage driving device using a gray voltage DAC which is more efficient than the above methods.

An object of the present invention is to provide a gray scale voltage DAC and a flat panel gray scale voltage driving device using the same.

In addition, an object of the present invention is to develop a gray voltage DAC and a flat panel gray voltage driving device using the same, thereby solving the problems of accuracy, wide circuit area, and large power consumption of a conventional gray voltage driving device.

In order to achieve the above objects, according to an aspect of the present invention, the voltage generator for generating at least one reference voltage; A digital analog control signal generator configured to generate at least one bit gray level voltage control signal corresponding to at least one reference voltage generated by the voltage generator and at least one predetermined input signal; And a resistance string in which a resistor having a resistance value of R and a resistor having a resistance value of 2R are connected in series, and the total resistance value sequentially added from the resistance value of the initial resistance of the resistor string becomes an exponential gradation resistance value of 2. The first switch unit located every time, the second switch unit located whenever the total resistance value becomes the resistance value of the odd gray level calculated from the point where the first switch unit is connected, and the switch of the second switch unit are predetermined. And a third switch unit positioned whenever the number of times is increased, and opening and closing the first switch unit, the second switch unit, and the third switch unit corresponding to the gray voltage control signal generated by the digital analog control signal generator. And a gray voltage generator configured to generate a voltage, wherein the first switch unit, the second switch unit, and the resistor string include a transistor, and the first switch unit and The on resistance of the second switch unit is calculated by including the resistance value of the resistor string, and the first switch unit, the second switch unit, and the third switch unit hierarchically define the overall resistance value of the resistor string. A flat panel display gradation voltage driving device can be provided.

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In an exemplary embodiment, the total resistance value of the resistor string may be determined in correspondence with the gray voltage. The method may further include a 1/2 switch located at a point where the total resistance value sequentially added from the resistance value of the initial resistance of the resistance string becomes half of the total resistance value of the resistance string.

In addition, the gray voltage control signal generated by the digital analog control signal generator is a switch unit for controlling the first switch unit, the second switch unit and the third switch unit by receiving the lower five bits of a plurality of predetermined input bits. It may be characterized by generating a control signal. In addition, the gray voltage control signal generated by the digital analog control signal generation unit receives an input bit except the least one bit among a plurality of predetermined input bits and the first switch control signal and is twice as many as the number of input signals. The gray voltage control signal may be generated.

The gray voltage generator may further include a precharge switch configured to connect a lower voltage connected in series with the resistor string and a gray voltage output terminal to pre-charge the gray voltage. . The first switch unit may be smaller than the number of bits of the gray voltage control signal. The second switch unit may be half of the number of the gray voltage control signals.

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The present invention can provide a gray voltage DAC and a flat panel gray voltage driving device using the same.

In addition, the present invention can solve the problems of accuracy, wide circuit area, and large power consumption of the conventional gray voltage driving device by developing a gray voltage DAC and a flat panel display gray voltage driving device using the same.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically illustrating a conventional gradation voltage DAC compared with the present invention.

2 is a diagram schematically illustrating a driving circuit of a flat panel display device to which the present invention is applied.

3 is a diagram showing the overall configuration of an 8-bit gradation voltage driving device according to an embodiment of the present invention.

4 is a diagram illustrating a circuit of a 5-bit gray voltage generator according to an exemplary embodiment of the present invention.

5 is a view showing an example of selecting a switch in the resistance column of the present invention.

6 is a diagram illustrating a practical example of a gray voltage generator according to the present invention;

7 is a timing diagram illustrating a precharging method in a gray voltage generator according to the present invention.

8 is a view showing a DAC control signal generator according to the present invention.

9 is a graph showing the results of evaluating the performance of the gray voltage driving device of the present invention.

<Explanation of symbols for the main parts of the drawings>

401: first switch unit 403: second switch unit

405: third switch unit 407: resistance heat

Hereinafter, a gray voltage DAC and a flat panel display gray voltage driving device using the same will be described in detail with reference to the accompanying drawings.

2 is a view schematically illustrating a driving circuit of a flat panel display device to which the present invention is applied.

Referring to FIG. 2, a driving circuit of a flat panel display device to which the present invention is applied includes a shift register 201, an input register 203, a storage register 205, and a voltage gray DAC 207.

The shift register 201 is a logic circuit that stores a certain amount of data while sequentially shifting input data between memory elements by forming memory elements such as flip-flops and latches in a row. In particular, the shift register used in the present invention is used for generating control signals or delaying data for a predetermined time using the synchronization signals 211 and 213. In particular, it instructs the input register 203 to store the display signal.

The input register 203 receives a command of the shift register 201 and sequentially receives a display signal received from the serial interface 215.

The storage register 205 stores the display signal received from the input register 203 and passes the stored signal to the voltage gray DAC 207.

The voltage gray DAC 207 is responsible for generating a gray voltage corresponding to the display signal input from the storage register 205. Unlike the display signal, the gray voltage is an analog signal because of the magnitude of the voltage. The magnitude of the voltage is generated by dividing the reference voltage 217 input from the outside using a series resistor, a capacitor, or the like. In the present invention, the gray scale voltage is generated by dividing the voltage using a series resistance component.

In particular, the method of dividing the gray voltage will be described in detail in the following drawings.

3 is a diagram illustrating the overall configuration of an 8-bit gradation voltage driving device according to an embodiment of the present invention.

Referring to FIG. 3, the 8-bit gray voltage voltage driving device includes a voltage generator 300, a DAC control signal generator 310, and a gray voltage generator 320. In general, the gray voltage generator 320 and the DAC control signal generator 310 may be referred to as a gray voltage DAC.

The voltage generator 300 is a part for generating a reference voltage of the gray voltage DAC. In the voltage generator 300, nine reference voltages are generated from Vref_1 to Vref_9 in the case of 8 bits.

The DAC control signal generator 310 generates an 8-bit DAC control signal using the nine reference voltages 310 and the input signals D0 to D7 generated by the voltage generator 300. The 8-bit DAC control signal first selects voltages corresponding to Vref_L and Vref_H among the 9 reference voltages using the upper 3 bits, and the remaining 5 bits are selected signals generated inside the DAC control signal generator 310. And a resistor string included in the gray voltage generator 320.

The gray voltage generator 320 is an essential part of the present invention, and includes a resistor string connected in series and a switch for generating an appropriate gray voltage by dividing the resistor string. The control of the switch included in the gray voltage generator 320 is controlled by the control signal generated by the DAC control signal generator 310.

In addition, the Vref_H and Vref_L voltages connected from the DAC control signal generator to the gray voltage generator are voltages corresponding to the reference voltages generated by the voltage generator. Play a role. The existing structure of the gray voltage generator takes up a large area and expends power as the number of switches connected to the resistor string of the gray voltage generator 320 and the number of resistors increase exponentially. Although large, it can be reduced by using the structure according to the present invention.

4 is a diagram illustrating a circuit of a 5-bit gray voltage generator according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the gray voltage generator of the present invention includes a resistor string 407, a first switch 401, a second switch 403, and a third switch 405.

The gray voltage generator of the present invention flows to a plurality of resistor strings 407 connected in series with an external reference voltage 409. The resistance value connected to the resistance string depends on the total number of gradations to be expressed. For example, if 32 gradations are to be expressed, a resistance value that can vary by 1/32 of the voltage value is R, and the total resistance value of the resistors connected in series becomes 32R. In this case, in the conventional resistance train method, 32 resistors having a size of R are connected in series, and a switch between them is used to output a voltage having a difference of 32 gradations. However, in the present invention, since the switch is not connected to all the resistors, by dividing the size of the resistor into R and 2R, if the resistance value corresponding to 2R is replaced with one resistor, only 20 resistors can be used. That is, the number of resistors can be drastically reduced by using a resistor having a resistance of R and a resistor having a resistance of 2R. Here, R value is an arbitrary resistance value, and does not mean a specific resistance value, but is a resistance ratio for partial voltage, for example, when the total resistance is 32R, for example, 1R value is 1/2 of 2R value. Such R value may be selected according to the actual implementation.

The first switch unit 401 is a switch for controlling the voltage drop of the resistor string 407. The first switch unit 401 is a switch connected whenever the total size of the resistors connected in series becomes 4R, 8R, 16R, and 32R. In the present invention, since it is set to represent 5 bits, that is, 32 gradations, the switch exists only up to 32 R. However, if the gradation is increased to N bits, that is, to represent 2 ^N gradations, the first switch unit 401 becomes 2 ^m R every time. M is a natural number equal to or greater than 2 and equal to or less than N. Here 2 ^N R represents the resistance of the entire resistance train. The resistor string 407 has a size of 2 ^N R because the voltage gray scale is represented by N bits. Is done.

The second switch unit 403 is a switch unit connected to a resistor string so as to operate together with the first switch unit 401 to select a detailed voltage gray scale.

The second switch unit 403 is connected to a portion where the total resistance becomes an odd value based on the resistance connected to the first switch unit 401. That is, when SW _1/4 , which is one of the first switch units 401, is used as a reference, the second switch unit 403 has two switches in front of SW _1/4 , and each position is the sum of the resistance values R. In the case of 1R and in the case of 3R, respectively.

In the same manner, it can be seen that the second switch unit 403 is connected at the point where the total resistance becomes 1R, 3R, 5R, and 7R by calculating from the SW _1/8 switch after the SW _1/16 switch. The same applies to the remaining SW _1/32 and SW _1/8 . As a result, one switch of the second switch unit 403 is connected to a resistor having an R resistance value based on the switch of the first switch unit 401, and then one after the resistance value of 2R is connected thereafter. When connected in this way, a resistor having a resistance value of 2R in the middle does not have to physically take the form of R + R, so a single resistor having a resistance value of 2R can be used to dramatically reduce the number of resistors used in the resistor string. have. As a result, the second switch unit can express all the gray levels by using only half of the gray scale numbers that can be expressed. In other words, if the resistance value of the entire resistance train is 2 ^N R, only 2 ^N / 2 is required. In the present invention, since the resistance value of the entire resistance string is 32R, the number of the second switch units will be 16.

Finally, in the present invention, the reference numeral 411 switch is added to represent 1/2 gray scale. The resistor 411 is not used only in the above position, and may be located anywhere where the gray scale voltage is 1 / 2V by calculating the value of the resistor string. That is, in the present invention, since the second switch part is connected to only the odd part between the first switch parts, there is a switch representing 1/2 gray scale such as 1/2, 2/4, 4/8, 8/16, 16/32. I never do that. Therefore, a switch for expressing 1/2 gray scale should be separately represented, which is a switch of reference numeral 411. The reference numeral 411 switch of this figure represents a 4/8 switch.

The third switch unit 405 is a switch unit for controlling the second switch unit. In the present invention, the third switch unit is a hierarchical switch unit for switching an efficient voltage gray scale according to a signal transmitted from a switch control circuit.

When the gray voltage generator is configured to operate in a hierarchical manner as described above, the number of switches and the number of resistors can be reduced as compared with the conventional method, and the area occupied by the circuit can be significantly reduced.

5 is a diagram illustrating an example of selecting a switch in the resistor string of the present invention.

Fig. 5A is a switch configuration showing 32/32 gray scales. For 32/32 switch configurations, close the SW _1/32 switch at 507 and also close the SW _pre switch at 520, which leads to DAC_out. In this case, since the Vref_H voltage passes all 32 resistance values and is output through the SW _pre switch, the voltage of 32/32 gray level can be output. In this case, however, the voltage charging speed may be reduced by passing through the resistance of the resistor string. In this case, the output buffer may be added to the output side, or the output buffer may be removed using the pre-charging method described with reference to FIG. 7.

Fig. 5B is a switch configuration showing half gray scale. In the case of the 1/2 switch configuration, as shown in FIG. 5B, the SW _1/8 switch 503 and the 1/2 switch reference number 523 and the third switch unit Q3 switch 511 are used in the first switch unit. Express it by closing it.

When the switch is closed as described above, the total resistance becomes 8R between Vref_H and Vref_L, and the 1/2 switch 523 becomes a switch which divides the total resistance 8R into 2R by 4R + 4R. Therefore, the voltage output through the 1/2 switch is 1 / 2V to represent 1/2 gray scale.

Fig. 5C is a switch configuration showing 3/4 gray scales. In the case of the 3/4 switch configuration, as shown in FIG. 5C, the SW _1/4 switch 501 in the first switch unit, the P2 switch 521 switch in the second switch unit, and the Q3 switch 511 in the third switch unit are illustrated. ) To close it.

When the switch is closed as described above, the total resistance becomes 4R between Vref_H and Vref_L, and the P2 switch 521 becomes a switch that divides the total resistance 4R by 3/4 equal to 3R + 1R. Therefore, the voltage output through the P2 switch is 3 / 4V to represent 3/4 gray scale. As described above, gray levels that can be expressed using the SW _1/4 switch in the first switch unit include 1/4 and 3/4 gray levels.

5D is a switch configuration showing 7/8 gradations. In the case of the 7/8 switch configuration, as shown in FIG. 5D, the SW _1/8 switch 503 in the first switch unit, the P0 switch 525 switch in the second switch unit, and the Q3 switch 511 in the third switch unit are illustrated. ) To close it.

When the switch is closed as described above, the total resistance is 8R between Vref_H and Vref_L, and the P0 switch 525 becomes a switch that divides the total resistance 8R by 7/8 by 7R + 1R. Therefore, the voltage output through the P0 switch is 7 / 8V to represent 7/8 gray scale. As described above, the gray scales that can be expressed using the SW _1/8 switch in the first switch unit include 1/8, 3/8, 5/8, and 7/8 gray scales.

Fig. 5E is a switch configuration showing 15/16 gray scales. In the case of the 15/16 switch configuration, as shown in FIG. 5E, the SW _1/16 switch 505 in the first switch unit, the P0 switch 527 switch in the second switch unit, and the Q2 switch 513 in the third switch unit are shown. ) To close it. In this case, the P0 switch 527 is a switch associated with the Q2 switch and is present at a different position from the P0 switch 525 described with reference to FIG. 5D.

When the switch is closed as described above, the total resistance becomes 16R between Vref_H and Vref_L, and the P0 switch 527 becomes a switch that divides the total resistance 16R by 15/16 equal to 15R + 1R. Therefore, the voltage output through the P0 switch 527 becomes 15 / 16V to represent 15/16 gray scale. As described above, the gradation that can be expressed using the SW _1/16 switch in the first switch unit is 1/16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16, and 15 There are / 16 gradations.

Fig. 5F is a switch configuration showing 31/32 gray scales. In the case of the 31/32 switch configuration, as shown in FIG. 5F, a SW _1/32 switch 507 in the first switch unit, a P0 switch 529 switch in the second switch unit, and a Q0 switch 515 in the third switch unit are used. ) To close it. Here, the P0 switch 529 is a switch associated with the Q0 switch, and is a switch which exists at a different position from the P0 switches 525 and 527 described with reference to FIGS. 5D and 5E.

When the switch is closed as described above, the total resistance becomes 32R between Vref_H and Vref_L, and the P0 switch 529 becomes a switch that divides the total resistance 32R into 31R + 1R by 31/32. Therefore, the voltage output through the P0 switch 529 becomes 31 / 32V to represent 31/32 gray scale. As described above, the gradation that can be expressed using the SW _1/32 switch in the first switch unit is 1/32, 3/32, 5/32, 7/32, 9/32, 11/32, 13 / 32,15 There are / 32, 17/32, 19/32, 21/32, 23/32, 25/32, 27/32, 29/32 and 31/32 gradations. Of course, up to 15/32 gradations will be output via the Q1 switch and from 17/32 through the Q0 switch.

When calculating the gray scales that can be output from 5a to 5f as described above, 1 in FIG. 5a becomes 32/32, 1/2 in FIG. 5b becomes 16/32, and 1/4 and 3/4 in FIG. 8/32, 24/32, 1/8, 3/8, 5/8, 7/8 in Fig. 5d become 4/32, 12/32, 20/32, 28/32, and 1 in Fig. 5e. / 16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16, 15/16 is 2/32, 6/32, 10/32, 14/32, 18/32 , 22/32, 26/32, 30/32, and Figure 5f shows 1/32, 3/32, 5/32, 7/32, 9/32, 11/32, 13 / 32,15 / 32, The gradation of 17/32, 19/32, 21/32, 23/32, 25/32, 27/32, 29/32, 31/32 is expressed to represent all 32 gradations.

6 is a diagram illustrating a practical example of a gray voltage generator according to the present invention. FIG. 6 has a structure substantially the same as that described in FIG. However, when a general resistor is used as the resistor string as shown in FIG. 5, the area of the resistor may be excessively large, and the accuracy of the gray voltage may be degraded due to the resistor string resistor and the connection resistance of the switch. The modified form is shown.

In particular, in the case of using a general resistance train, there is a disadvantage in that an error voltage may be increased due to an on resistance of a connection switch. On the other hand, when a TFT is applied as a resistor by using a property that acts as a resistor when a constant voltage is applied to the TFT, the resistance heat can be directly configured in a small area, and its characteristics may be better than a general resistor.

7 is a timing diagram illustrating a precharging method in a gray voltage generator according to the present invention.

Referring to FIG. 7, the SWpre switch 701 serves as a switch for expressing 32/32 gray levels as described with reference to FIG. 5A, but also plays a role of quickly filling the gray voltage through precharging. As can be seen from the timing diagram, the precharging is performed by directly filling a predetermined voltage (Vref_L) before the gray voltage is formed by the combination of the SW_1 / 2n switch 710 and the Py switch 720. It serves to shorten the time to fill the gradation voltage through.

Since the resistor string for generating the gray voltage has a large resistance value, it takes a long time to fill the required gray voltage, thereby overcoming the disadvantage of the existing technology of adding an analog output buffer.

8 is a diagram illustrating a DAC control signal generator according to the present invention.

Referring to FIG. 8, the switch control circuit is configured to select the first switch unit 803 of FIG. 4 from the reference voltage selector 810 according to the lower three-bit gray level 801.

Thus, the first switch unit 803 can be selected using only the lower 3 bits. The principle will be described in the following table.

If the denominator is 32 Gradation D4 D3 D2 D1 D0 1/32 0 0 0 0 One 3/32 0 0 0 One One 5/32 0 0 One 0 One 7/32 0 0 One One One 9/32 0 One 0 0 One 11/32 0 One 0 One One 13/32 0 One One 0 One 15/32 0 One One One One 17/32 One 0 0 0 One 19/32 One 0 0 One One 21/32 One 0 One 0 One 23/32 One 0 One One One 25/32 One One 0 0 One 27/32 One One 0 One One 29/32 One One One 0 One 31/32 One One One One One

If the denominator is 16 Gradation D4 D3 D2 D1 D0 1/16 0 0 0 One 0 3/16 0 0 One One 0 5/16 0 One 0 One 0 7/16 0 One One One 0 9/16 One 0 0 One 0 11/16 One 0 One One 0 13/16 One One 0 One 0 15/16 One One One One 0

Denominator 8 Gradation D4 D3 D2 D1 D0 1/8 0 0 One 0 0 3/8 0 One One 0 0 5/8 One 0 One 0 0 7/8 One One One 0 0

Denominator 4 Gradation D4 D3 D2 D1 D0 1/4 0 One 0 0 0 3/4 One One 0 0 0

Denominator 2 Gradation D4 D3 D2 D1 D0 1/2 One 0 0 0 0

As described above, when the denominator is 32, all grays of the D0 bits may be expressed as one. If the bits D1 and D0 are 10, the denominator is only 16. If the bits D2, D1 and D0 are 100, the denominator is only 8, and if the bits D2, D1 and D0 are 000, the denominator is 2. And 4 only. However, in the present invention, since the denominator is 2, the switching is not performed. Thus, only the bits D2, D1, and D0 are used, so that the switching 803 according to the denominator is possible. Therefore, it is easy to select using the decoder type reference voltage selector 810.

After selecting the denominator switch, the upper four bits of the voltage gray level and the first switch selector signal 803 are input from the reference voltage selector 810 to the bit shifter 820 to select the molecular switch. Then, the bit shifter 820 shifts the bit according to the value of the first switch unit selection signal 803 to output the intermediate output value 813, and outputs the value to the two input four output decoder 830 to output the second switch unit. 403 and a switch 405 that controls the molecular switch.

When the control signal is generated in this manner, it can be implemented using only about 50% of devices compared to the conventional method, and even when using a ROM type switch arrangement, only 70% of devices can be implemented.

9 is a graph showing the results of evaluating the performance of the gradation voltage driving device of the present invention.

Referring to FIG. 8, a graph of reference numeral 910 is a graph confirming stepwise charging of the gray scale voltage in a VGA-class flat panel display. As shown in the graph, it shows that a given load is well charged without a special analog buffer.

A graph of reference numeral 920 is a graph showing an error voltage distribution of all grays of the gray voltage driving apparatus according to the present invention. As can be seen from the graph, it can be seen that the LSB error is lower than 0.6 in all intervals. In this case, it can be seen that the power consumption is about 15mW.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

Claims (14)

A voltage generator configured to generate at least one reference voltage; A digital analog control signal generator configured to generate at least one bit gray level voltage control signal corresponding to at least one reference voltage generated by the voltage generator and at least one predetermined input signal; And When a resistor having a resistance value of R and a resistor having a resistance value of 2R are connected in series with each other in series, and the total resistance value sequentially added from the resistance value of the initial resistance of the resistor string becomes an exponential gradation resistance value of 2. The first switch unit located every time, the second switch unit located every time the total resistance value becomes the resistance value of the odd gray level calculated from the point where the first switch unit is connected, and the switch of the second switch unit And a third switch unit positioned each time the number is changed, and opening and closing the first switch unit, the second switch unit, and the third switch unit corresponding to the gray voltage control signal generated by the digital analog control signal generator. Including a gray voltage generator for generating a, The first switch unit, the second switch unit and the resistor string are composed of a transistor, the on-resistance of the first switch portion and the second switch portion is calculated by including the resistance value of the resistor string, And the first switch unit, the second switch unit, and the third switch unit hierarchically limit the overall resistance values of the resistor strings to generate the gray scale voltages. The method of claim 1, And a total resistance value of the resistance string is determined in correspondence with the gray voltage. delete delete The method of claim 1, And a 1/2 switch positioned at a point at which the total resistance value, which is sequentially added from the resistance value of the initial resistance of the resistance string, becomes half of the total resistance value of the resistance string. delete The method of claim 1, The gray voltage control signal generated by the digital analog control signal generator is a switch control signal for controlling the first switch unit, the second switch unit and the third switch unit by receiving the lower 5 bits of a plurality of predetermined input bits. Flat display display voltage driving device characterized in that for generating a. The method of claim 7, wherein the gray voltage control signal generated by the digital analog control signal generation unit receives input bits other than the least significant one bit among a plurality of predetermined input bits and the number of input signals by receiving the first switch control signal. A flat panel display gradation voltage driving device, characterized in that to generate twice the gradation voltage control signal. The method of claim 1, The gray voltage generator further includes a flat charging switch connecting a lower voltage connected in series with the resistor string and a gray voltage output terminal to pre-charge the gray voltage. drive. The method of claim 1, And the first switch unit is one smaller than the number of bits of the gray voltage control signal. The method of claim 1, And the second switch unit is half the number of the gray voltage control signals. delete delete delete