KR20020052715A - Source driver in tft-lcd - Google Patents

Abstract

PURPOSE: A source driver of a TFT-LCD is provided to display a picture of desired color number by selecting arbitrarily bit number of data. CONSTITUTION: A mode selector(710) generates a signal for selecting modes of a source driver according to mode selection signals(S1,S2). A data selector(720) selects R, G, and B data of constant bits from R, G, and B data of predetermined bits received from the outside according to the signals of the mode selector(710). A data register(200) stores sequentially the data selected from the data selector(720) according to a clock signal of a shift register(100). The data register(200) stores only R, G, and B data of 4 bits of an upper portion from R, G, and B data of 8 bits received from the outside according to a mode of the mode selector(710). The remaining data of 4 bits are fixed to a low level. A hold register(300) holds the R, G, and B data of 4 bits of the data register(200). A level shifter(400) converts the R, G, and B data of 4 bits of the hold register(300). A data control unit(730) modifies the R, G, and B data of 4 bits of the level shifter(400) to R, G, and B data of 8 bits. A digital/analog converter(500) converts the digital data of the data control unit(730) to analog data. An output buffer(600) provides the analog data to an LCD panel.

Description

Source Driver of Thin Film Transistor-LCD {SOURCE DRIVER IN TFT-LCD}

The present invention relates to a TFT-LCD source driver, and more particularly, to a source driver capable of obtaining various color numbers by selecting the number of bits of input data and reducing current consumption.

The source driver IC for TFT-LCD drives a liquid crystal display device, and according to the characteristics and application of the liquid crystal display device, the number of color colors to be supported varies, thus forming a variety of products according to the number of RGB data bits.

According to the number of data bits, eight colors are displayed for each one bit of R, G, and B data, and 64 colors are used for each two bits of R, G, and B data. In addition, 512 colors for each 3 bits, 4096 colors for each 4 bits, 32768 colors for each 5 bits, 262144 colors for each 6 bits, 2097152 colors for each 7 bits, and 8 bits for each bit 16777216 colors can be displayed.

Therefore, the more expensive the liquid crystal display device is, the higher the color driver source driver IC is used, and in the case of a lower product, the lower driver device driver IC is used. As a result, production lines are complicated and manufacturing costs are increased to produce source driver ICs having various types of data bits. In addition, the diversity of source drivers can create confusion between suppliers and users.

Fig. 1 shows a source driver of a conventional TFT-LCD.

Referring to FIG. 1, a conventional TFT-LCD source driver is an 8-bit source driver. The TFT-LCD source driver is a data register for sequentially storing 8-bit R, G, and B data in accordance with the clock signal of the shift register 100. 200, a hold register 300 for inputting and holding R, G, and B data applied from the data register 200 according to the load signal LOAD, and R, G applied from the hold register 300. And a level shifter 400 for converting B data to a level suitable for a liquid crystal panel (not shown), and converting the R, G, and B data level-converted through the level shifter 400 into analog data. The digital-to-analog converter 500 and the output buffer 600 for driving the liquid crystal panel by providing the analog data converted through the digital-analog converter 500 to the liquid crystal panel.

The operation of the conventional TFT-LCD source driver having the configuration as described above is as follows.

First, the data register 200 sequentially stores the data applied from the shift register 100 to R, G, and B data of 8 bits applied from the outside. The R, G, and B data stored in the data register 200 are held in the hold register 300 by the load signal LOAD and then converted into a signal level suitable for driving the liquid crystal panel through the level shifter 400.

The R, G, and B data level-converted through the level shifter 400 are applied to the digital-analog converter 500 and converted into analog data. Therefore, since the grayscale voltage corresponding to each of the R, G, and B data is generated from the digital-analog converter 500 and applied to the output buffer 600, the output buffer 600 is output from the digital-analog converter 500. The liquid crystal panel is driven according to the gray scale voltage to display R, G, and B data.

The conventional TFT-LCD source driver as described above is an 8-bit source driver, which represents the number of colors corresponding to 8 bits, and, if necessary, displays a source driver of a corresponding bit when displaying data of another bit. There was a problem that must be used.

The present invention is to solve the problems of the prior art as described above, TFT-LCD source which can display the image of the desired color number by arbitrarily selecting the number of bits of the input data, and can also reduce the current consumption The purpose is to provide a driver.

1 is a configuration diagram of a source driver of a conventional TFT-LCD;

2 is a block diagram of a TFT-LCD source driver according to an embodiment of the present invention;

3 is a configuration diagram of a source driver of a TFT-LCD according to another embodiment of the present invention;

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

100: shift register 200: data register

300: Hold Register 400: Level Shifter

500: digital-to-analog converter 600: output buffer

710, 810: mode selector 720: data selector

730, 830: data control unit

The present invention for achieving the above object is a mode selector for generating a signal for selecting a mode of the source driver in accordance with the mode selection signal; A data selector for storing only second R, G, and B data of the second bit number among the first R, G, and B data of the first bit number input from the outside according to a mode selection signal applied from the mode selector; A data register for sequentially storing only second R, G, and B data of the second number of bits provided from said data selector; A hold register for holding second R, G, and B data applied from said data register in response to a load signal; A level shifter for converting the second R, G, and B data applied from the hold register to a level suitable for driving the liquid crystal panel; A data control unit for inputting level-converted second R, G, and B data to generate third R, G, and B data having a first number of bits; A digital-analog converter for converting third R, G, and B data generated from the data control unit into analog data; It provides a TFT-LCD source driver consisting of an output buffer for driving the liquid crystal panel by providing the analog data converted through the digital-to-analog converter to the liquid crystal panel.

The data register stores the second R, G, and B data of the second number of bits applied from the outside in the order of higher bits, and fixes the remaining bits at the same logic level.

The second R, G, and B data stored in the higher bit order of the data register may be data for representing a gray level selected according to the mode selection signal.

The number of first bits of the R, G, and B data is greater than or equal to the number of second bits, and the data control unit is a higher-order bit of the second R, G, and B data of the second number of bits level-converted from the level shifter. The third R, G, and B data of the first number of bits are generated by replacing them in order.

The present invention also provides a mode selector for generating a signal for selecting a mode of a source driver according to a mode selection signal; In response to the mode selection signal applied from the mode selector, only the second bits of the first bits of the first R, G, and B data, the second bits of the second bits of the second R, G, and B data are input, and the third bits of the first number of bits are input. A data control unit for generating G, B data; A data register for sequentially storing third R, G, and B data of the first number of bits provided from said data control unit; A hold register for holding third R, G, and B data applied from said data register in response to a load signal; A level shifter for converting the third R, G, and B data applied from the hold register to a level suitable for driving the liquid crystal panel; A digital-to-analog converter for converting the level-converted third R, G, and B data into analog data; It provides a TFT-LCD source driver consisting of an output buffer for driving the liquid crystal panel by providing the analog data converted through the digital-to-analog converter to the liquid crystal panel.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail.

2 is a block diagram of a TFT-LCD source driver according to an embodiment of the present invention. Fig. 2 shows a configuration example in the case where only 4-bit data is selectively used as an 8-bit source driver.

Referring to FIG. 2, the TFT-LCD source driver according to an exemplary embodiment of the present invention may include a mode selector 710 for generating a signal for selecting a mode of a source driver according to mode selection signals S1 and S2. And a data selector 720 for selecting only R, G, and B data of a predetermined bit among R, G, and B data of a predetermined bit input according to a mode selection signal applied from the mode selector 710, and the data. And a data register 200 for sequentially storing data selected from the selector 720 in accordance with the clock signal of the shift register 100.

The data register 200 stores only the upper 4 bits R, G, and B data among the 8 bits of R, G, and B data applied from the outside according to the mode of the mode selector 710, and the upper 4 bits of the 8 bits. Stores upper 4 bits of R, G, and B data applied from the outside, and fixes the remaining lower 4 bits at a low level.

In addition, the TFT-LCD source driver of the present invention is a hold register for inputting and holding a predetermined bit, for example, four bits of R, G, and B data applied from the data register 200 according to a load signal LOAD ( 300 and a level shifter 400 for converting 4-bit R, G, and B data applied from the hold register 300 to a level suitable for a liquid crystal panel (not shown).

In addition, the TFT-LCD source driver of the present invention is a data control unit for making 8-bit R, G, B data by inputting the 4-bit R, G, B data level-converted through the level shifter 400 ( 730, a digital-to-analog converter 500 for converting digital data generated from the data control unit 730 into analog data using a reference voltage VR, and through the digital-to-analog converter 500. The output buffer 600 drives the liquid crystal panel by providing the converted analog data to the liquid crystal panel.

Referring to the operation of the TFT-LCD source driver according to another embodiment of the present invention having the configuration as described above is as follows.

First, the mode selector 710 selects a mode of the source driver in accordance with the mode selection signals S1 and S2, and only 8 bits of R, G, and B data are externally transmitted by the data selector 720. The data register 200 is applied to the register 200 and stored in accordance with the clock signal of the shift register 100.

At this time, the data register 200 has predetermined bits of R, G, and B by the data select 720 according to a mode selected by the mode selector 710 among 8 bits of R, G, and B data applied from the outside. Only data is selected and stored. For example, when the data selector 720 selects and stores only 4 bits of R, G, and B data in the data register 200 according to the mode selected by the mode selector 710, 8 applied from the outside is applied. Only the upper four bits of the R, G, and B data of the bits are stored in the upper four bits of the data register 200, and the remaining lower four bits of the data register 200 are fixed at the low level. .

On the other hand, when the data selector 720 selects only 6 bits of R, G, and B data and stores them in the data register 200 according to the selected mode of the mode selector 710, an 8-bit R applied from the outside is applied. The R, G, and B data of the upper 6 bits of the G, B data are stored in the upper 6 bits of the data register 200, and the remaining lower 2 bits of the data register 200 are fixed at a low level.

The 4-bit R, G, and B data stored in the data register 200 are held in the hold register 300 by a load signal LOAD and then provided to the level shifter 400 to provide a signal level suitable for driving the liquid crystal panel. Is converted to.

The R, G, and B data level-converted by the level shifter 400 are applied to the data control unit 730 to generate 8-bit R, G, and B data, which is externally based on the mode selected from the mode selector 710. When only 4-bit data among R, G, and B data is selected, the upper 4 bits store the upper 4 bits of R, G, and B data from the outside, and the remaining lower 4 bits store the upper 4 bits of data. The upper 4 bits of 8-bit R, G, and B data are stored sequentially.

On the other hand, when only 6-bit data of the external R, G, and B data is selected according to the mode selected by the mode selector 710, the upper 6 bits of data of the upper 6 bits of the 8-bit R, G, and B data from the outside are selected. Is stored, and the remaining lower 2 bits are sequentially stored with the upper 2 bits of the 8-bit R, G, and B data from the outside.

In other words, according to the mode selected by the mode selector 710, the corresponding upper constant bit among 8-bit R, G, and B data from the outside is used as it is, and the upper constant bit is applied to the lower bits fixed to the remaining low levels. By sequentially replacing, 8-bit R, G, and B data corresponding to the mode selected by the mode selector 710 are generated.

Table 1 shows the number of gradation voltages, mode selection signals, and output relations of data registers and control units in each mode when the 8-bit source driver of the present invention is used.

D7: Most significant bit (MSB) D0: least significant bit (LSB)

The 8-bit R, G, and B data output from the data control unit 730 are provided to the digital-analog converter 500, and the digital-analog converter 500 uses the 8-bit R inputted using a reference voltage. A gray voltage corresponding to the G, B data is generated and provided to the output buffer 600.

In this case, when only the upper 4 bits of the external 8-bit R, G, and B data are used in accordance with the mode selected by the mode selector 710 as described above, only 16 equal gray scales of 256 gray scales are required. If only 6 bits are used, only an even 64 gradations are needed.

Table 2 shows data for selecting a reference voltage according to each mode of Table 1 when the 8-bit source driver of the present invention is used.

According to an embodiment of the present invention as described above, first, the desired mode is selected through the mode selector 710, and the data selector 720 is applied from the outside according to the mode selected by the mode selector 710. Only the data of the corresponding higher bit among the R, G, and B data of the bit is stored in the data register 200, and the 4-bit data stored in the data register 200 is again provided to the data control unit 730 to provide 8-bit data. Are converted to R, G, and B.

Therefore, when a user selects a mode according to the desired number of colors, various colors may be implemented using one source driver by performing gray level conversion using only a part of external R, G, and B data according to the selected mode.

In addition, in one embodiment of the present invention, by storing only the desired number of data bits and fixing the remaining bits at a low level, current consumption in digital components of the source driver can be reduced.

3 is a block diagram of a TFT-LCD source driver according to another exemplary embodiment of the present invention.

Another embodiment of the present invention shown in FIG. 3 is an 8-bit source driver, and illustrates a configuration example in which a chip size reduction effect can be obtained rather than current consumption.

Referring to FIG. 3, a TFT-LCD source driver according to an embodiment of the present invention includes a mode selector 810 for generating a signal for selecting a mode of a source driver according to a mode selection signal, and a mode selector 810 from the mode selector 810. According to the mode selection signal applied from the outside, R, G, B data of a predetermined bit among R, G, B data of a predetermined bit is selected to make R, G, B data of a predetermined bit suitable for the mode selection signal. A data register 200 for sequentially storing 8-bit R, G, and B data provided from the data control unit 830 in accordance with a clock signal of the shift register 100 and a data control unit 830 for giving. It includes.

In addition, the TFT-LCD source driver of the present invention includes a hold register 300 for inputting and holding 8-bit R, G, and B data applied from the data register 200 according to a load signal LOAD, and the hold. And a level shifter 400 for converting 8-bit R, G, and B data applied from the register 300 to a level suitable for a liquid crystal panel (not shown in the figure).

In addition, the TFT-LCD source driver of the present invention inputs 8-bit R, G, B data level-converted through the level shifter 400 and converts the digital data into analog data using a reference voltage VR. An analog converter 500 and an output buffer 600 for driving the liquid crystal panel by providing the analog data converted through the digital-analog converter 500 to the liquid crystal panel.

Referring to the operation of the TFT-LCD source driver according to another embodiment of the present invention having the configuration as described above is as follows.

First, the mode selector 810 selects a mode of a source driver in accordance with mode selection signals S1 and S2, and the data control unit 830 selects a mode selection signal from the outside according to a mode selection signal output from the mode selector 810. Only the desired data is input from the 8-bit R, G, and B data to generate 8-bit R, G, and B data corresponding to the selected mode as described in FIG.

The 8-bit R, G, and B data provided from the data control unit 830 are sequentially stored in the data register 200 by the clock signal output from the shift register 100.

The 8-bit R, G, and B data stored in the data register 200 are held in the hold register 300 by a load signal LOAD and then provided to the level shifter 400 to provide a signal level suitable for driving the liquid crystal panel. Is converted to.

The R, G, and B data level-converted by the level shifter 400, the digital-to-analog converter 500 generates a grayscale voltage corresponding to 8-bit R, G, and B data input using a reference voltage to output the buffer. Provided at 600.

According to the TFT-LCD source driver according to another embodiment of the present invention as described above, by arranging the data control unit 830 between the mode selector 810 and the data register 200, the user does not need a data selector Since various color numbers can be implemented by selecting arbitrary data bits, the chip size can be relatively reduced than in the exemplary embodiment.

In the TFT-LCD source drivers according to the first and second embodiments of the present invention, when the 256 gray levels are to be expressed, all of the mode selection signals S1 and S2 become low level, and the data selector 720 or the data control unit is used. The 830 inputs 8-bit data applied from the outside as it is, and operates as a normal source driver.

Therefore, according to the source driver of the TFT-LCD of the present invention as described above, since the user can obtain a desired number of colors by arbitrarily selecting the R, G, and B data input from the outside, various colors can be obtained by using one source driver. It is possible to display an image with a number.

Therefore, by applying the TFT-LCD source driver of the present invention to a liquid crystal panel for displaying a variety of color numbers with one IC, not only can it provide convenience in use, but it can also reduce the manufacturing cost by simplifying the production line. .

In addition, the source driver of the present invention reduces power consumption as the number of low bits among R, G, and B data applied from the outside, that is, the smaller the number of gradations, is applicable to portable devices.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (9)

A mode selector for generating a signal for selecting a mode of the source driver according to the mode selection signal; A data selector for storing only second R, G, and B data of the second bit number among the first R, G, and B data of the first bit number input from the outside according to a mode selection signal applied from the mode selector; A data register for sequentially storing only second R, G, and B data of a second number of bits provided from said data selector; A hold register holding the second R, G, and B data applied from the data register according to a load signal; A level shifter for converting the second R, G, and B data applied from the hold register to a level suitable for driving the liquid crystal panel; A data control unit for inputting level-converted second R, G, and B data to generate third R, G, and B data having a first number of bits; A digital-analog converter for converting third R, G, B data generated from the data control unit into analog data; And Output buffer for driving the liquid crystal panel by providing the analog data converted by the digital-to-analog converter to the liquid crystal panel TFT-LCD source driver, characterized in that consisting of. The method of claim 1, The data register stores the second R, G, and B data of the second number of bits applied from the outside in the order of higher bits, and fixes the remaining bits at the same logic level. The method of claim 1, And the second R, G, and B data stored in the higher bit order of the data register are data for expressing a gray level selected according to the mode selection signal. The method of claim 1, And the first number of bits of the R, G, and B data is greater than or equal to the second number of bits. The method of claim 4, wherein Wherein the data control unit replaces the second R, G, and B data of the second bit number level-converted from the level shifter in the order of higher bits to generate the third R, G, and B data of the first bit number. -LCD source driver. A mode selector for generating a signal for selecting a mode of the source driver according to the mode selection signal; In response to the mode selection signal applied from the mode selector, only the second bits of the first bits of the first R, G, and B data, the second bits of the second bits of the second R, G, and B data are input, and the third bits of the first number of bits are input. Data control unit for generating G, B data; A data register for sequentially storing third R, G, and B data of the first number of bits provided from said data control unit; A hold register for holding third R, G, and B data applied from the data register according to a load signal; A level shifter for converting the third R, G, and B data applied from the hold register to a level suitable for driving the liquid crystal panel; A digital-analog converter for converting the level-converted third R, G, and B data into analog data; And Output buffer for driving the liquid crystal panel by providing the analog data converted by the digital-to-analog converter to the liquid crystal panel TFT-LCD source driver, characterized in that consisting of. The method of claim 6, And the second R, G, and B data of the second number of bits input by the data control unit are data for expressing a gray level selected according to the mode selection signal. The method of claim 6, And the first number of bits of the R, G, and B data is greater than or equal to the second number of bits. The method of claim 8, The data control unit replaces only the second R, G, and B data of the second number of bits among the R, G, and B data applied from the outside, in order of higher bit order, thereby making the third R, G, and B data of the first number of bits. TFT-LCD source driver, characterized in that the giving.