TW521254B - Circuit and method of source driving of TFT LCD - Google Patents

Abstract

A driving loop and driving method for source electrode of liquid crystal display (LCD) are disclosed in the present invention, wherein eight-bit driver can also be realized even when the conventional uniform engineering having six-bit driving loop is used. The source driving-loop of data line that uses image data to drive the LCD apparatus is featured with having the followings: a digital block for inputting the image data; a digital-analog (D-A) converter for converting the image data inputted from the digital block into the analog signal; an operation amplifier, which buffers the output of D-A converter and drives the data line; the first switch, which is ON at the first cycle of column time and transmits the operation amplifier output to the data line; the second switch, which is ON at the second cycle of column time and directly connects the D-A converter output to the data line. Therefore, in the invention, one column time that adds image signal to the data line is divided into two steps. In the first step, operation amplifier output is used to drive the data line of panel. In the second step, D-A converter output is used to directly drive the data line. By compensating the error, the performance of high gradation effect can be obtained even when the operation amplifier having uniformity of six-bit degree is used.

Description

521254 V. Description of the invention (1) [Technical category to which the invention belongs] The present invention relates to a driving circuit and a driving method of a liquid crystal display device, and more particularly to a liquid crystal capable of expressing a high color gradation (gradati ο η) using a simple circuit. Source driving circuit and driving method of display device. Generally, a liquid crystal display device (LCD) used to display text marks or graphics is a display device that combines the liquid crystal technology with semiconductor technology using the optical properties of liquid crystals with changes in the molecular arrangement produced by the electric field. An LCD using a thin film transistor (Thin Film Trans is to r; TFT) is used as a switching element for internal pixels (P i xe 1) 〇N / 〇FF. 〇N / 〇FF can make pixels 〇N / 〇FF. That is, as shown in the first figure, a general TF liquid crystal display device includes pixels (130) which are arranged in an array, and each element is composed of a TFT (130) and a liquid crystal element (1) that switch functions. 34) and storage capacitor C s. In addition, the source (Sorce) of each TFT is connected in common in the row (c ο 1 um η) direction to form a data line (D 1 ~ D Ν), and is then connected to the source driver (1 2 0), The gates of the TFs are connected in common in the row (rw) direction to form a scan line (S1 ~ SM), and are connected to a gate driver (1 1 0). A display device with a resolution of N × M (for example, SVG A is 800x600, XGA is 1024x768, and UXGA is 1600X1 2 0 0). Here, the source driver (1 2

Ο) :: one column (=, data drive or row drive, and gate drive drive). The movement is% h (; 3 port: no, the liquid crystal element (1 3 4) <-the side is via the T ^ surface actuator (1: Ϊ drain (d Γ 3 丨 11) and the pixel electrode and It is made with source A " 1 U mt 0 N: (indium tin oxide), and is applied to the TF gate, which is applied to the gate electrode: (1 2 〇) The signal T 〇 is formed as a Vulcan Bull 1 3 4) ′, and the common electrode is similarly stored, and a common voltage V c 0 m applied to the liquid crystal element is stored. The signal of Bu is based on; (The arrangement of 1 pixel can be used as a guard, and the liquid crystal fresh capacitor is charged and discharged by charging and discharging. This adjusts the light transmittance of the pixel. Store 1 twist to Transparent connection, the other side is connected with the common electrode. The pixel in the moon has conductivity I Ding 0, T-1 plus ° X i Η ... one ... "..." Electrode vertical electrode or gate electrode 5 (S The side of the liquid crystal of t 〇rage pixels uses the inverse method (η gae 〇η

= Data is periodically applied in reverse polarity] :; J applied 2 = System :: = ::: 7 In the opposite direction and the region uses the voltage polarity of the entire panel of the panel as _: It is included in each phase The area inversion method is the same as the line inversion method that distinguishes between the second and second switching even if it reverses the interaction of the lines;

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V. Description of the invention (3) Phase method and so on. (Since the voltage Vc is from the direction of D to D. On the one hand, there is a day-to-day ratio of 1; when FRC is used to adjust the ratio of the second a surface, at 1 it actually shows V 0 and V. No matter which method is used, the drain The voltage applied to the pixel alternates between positive (the voltage on the pixel voltage pole when it is inverted) is relative to the common +) direction or the negative (one) square w

The Lev method is more likely to produce flashes than the high-frequency vibratory interpolation. If the third order is used and any of the colors shown in the three b diagrams are twelve orders, then the liquid crystal adjustment method is used. () And the high-frequency method (FR maps of the day and the second example, the dual value is (1 1 in the middle e 1 G blinks (F 1 octets move) (di (inta chart base V 5 then, Four twelfth order, and when the four pixel display device F ram vibrates (d C) as shown in figure b of the first frame and the number of the day and / 2) (the gradation (the ray-icke hue display therep 〇) The quasi-voltage V shows that the tenth pixel is set to the color level. Two of them are high-rate Rate ither-a pictures and the time-balanced ones intersect V 〇 2 + V with four odd-numbered pictures; a low Scale r), the loop quality is poor ing) Method 1 ati ο 4 shows a unit of the sixth-order color gradation, then four like the eleventh and two shows the square of the fourteenth order Co ing 2 The method frame structure of b is mutually applied _ 2) Level gray)) ° The problem that will become is the first using η) Second, this field modulation method and a display of the average of four factors also include the n t r square) method. As shown in the drawing, the system 0 becomes a daytime V 0 and V 2, and the order can be displayed (L 〇 However, the square is complicated, and there is a method of spatial flatness. For example, the order and color of the order are displayed as the place in the pixel. Level 16. This bureau

V. Explanation of the invention (4) Due to the problem of P ## in the frequency vibration method, the order method must be provided in accordance with 6 4) and selected as shown in the fourth a and the fourth figure, (4 〇2 器 (4 〇4 " 〇6) The analog data of the clock signal latch data is converted by the source of the selected image.

In V

V

The number of inputs is ~ analog 1, D 2 · · The polarity of the video card input video is inverted. The fourth b shows the source driver 0) The data line is (4 1 〇 converter (DAC assembly often, widely funded correspondence) For a pole drive, number, and asset number, provide (4 to 4 conversion •) Image asset transfer to habit (4 series to) series: 4 Most pixels display the day image, so the resolution is obviously in six bits. The LC actuators are all analog input latches with the same input data as the input. The shifter sends the latch and the digital part is 103. The analog signal device (4 0. The data latches, wires Variable signal. The source of knowledge 10) and the resistor and the digital area 1 2) and the performance data are from the source of the six * bit D source shift value send converter (40 register ((40 analog conversion The six-bit. Output 3) locker (change the logic horse area and move back to the panel (capacitor block (4 calculations of the output signal bit display combination of the first stage of the electric drive register ((40 5), 4 0 1 2)) Converter (elementary digital buffer output and 4 0 5 converter (4 and the display shows sixty voltages (voltage plus 4 0 1 3), line transformation) is produced by latching 4 0 3 data transfer (40 drive data) is from 0 6) sixty-four-color four-color gradation system v 1 ~ v in turn. Figure. As the first) and latch The lock wheel comes out of the buffer logic to generate the latch clock signal.), The digits are replaced with 4) series feed lines (D is a schematic diagram of the kh supply line, not shown, 42). Panel (42 is equivalent Performance, and the source driver 1 1) and digital analog converter (4 1 3)

521254 V. Description of the invention (5) “One for one” is to provide driving signals for data lines. In Figure 4b, the digital block (a schematic diagram of the data input part for 4 1, and digital ~ * system combined source 2) is a system that converts digital image data into an analog signal to analog converter ((4 1 3 ) Is the output buffer function. The calculation is enlarged, but the conventional LCD and occasions as shown in Figure 4b are high-level octets, and the source drives the back-calculation amplifier (〇PA MP). The general analogy is that the wheel-out buffer must be within about 5 m V, and the project must meet the wheel-out error or another error compensation loop to meet this. The result will lead to an increase in the average area of the item '°. Complexity [Problem to be solved by the invention] The purpose of the present invention is to provide a source driving circuit and a driving method capable of solving the blindness of the device. It is also possible to implement the use of the drive. Eight [Methods to Solve the Problem] In order to achieve the aforementioned purpose, the method of the present invention is: • The device uses a source driver to drive the data line of the panel. The liquid crystal display device is equipped with a digital — The characteristics of the ratio ^ method are: ☆: will be applied to the data line of the panel: $ 演 篇: divided into two stages, in the first stage, the aforementioned U: is used to move the data line of the panel, 4 second The phase is based on the foregoing; the replacement is directly driven by the data line, and the difference in uniformity of the device driving the 4 1 device is compensated by the compensation error bit and its crystal display knowledge bit display. Transfer ratio

521254 V. Description of the invention (6) Six-bit calculations and calculations. In order to achieve the purpose of driving the liquid crystal display device with the aforementioned data, the data characteristics include: a digital block, a digital analog conversion. Device analog signal; the first cycle is

The material is converted into a ratio of the converter's travel time to the aforementioned information, and will be on the front line. The following [implements the fifth schematic diagram]. Panel performance, according to (411 (413, a switch, switch (S, fifth, widely used, PA, MP, etc.) will drive self-calculation to drive the aforementioned ON, and the material line; a second switch, the digital one, the performance of the analog converter is higher. The invention line is used for the aforesaid several devices, and the data line is used for the output color gradation of the line. The circuit is a type of source driver input before the block to image, and its special data; the dynamic circuit describes the image input image The first buffer is a type of buffering the aforementioned digital data; a first switch is connected to the aforementioned data in the second period of the output transmission time of the linear computing amplifier, and is directly connected to the foregoing information. The preferred embodiment of the present invention will be described in detail with reference to the drawings. , Is the source of the disclosure (5 2 0) and the digital Γ —) and the liquid crystal display pole driver with six: 4 1 3) which is not connected to the pattern of SW 1) and W 2). The analog conversion conversion of the data line driver is amplified in parallel to the conversion. The source bit level of the invention is similar to that of the source drive circuit of the eight-bit display device (510) and the panel (520 is equivalent to a resistor and a capacitor (5 2 0) is a digital blocker (4 1 2) The structure of the second pole driving circuit of the first amplifier (4 1 3) at the output end of the amplifier (41 3) is an item that is displayed using the current uniform amplifier (0 element color scale. Therefore,

Page 521 521254 V. Description of the invention (7) In the structure of the source driving circuit of the present invention, the same constituent elements as those of the conventional LCD source driver shown in FIG. 4b are marked with the same figure Show symbol. In addition, the source driver (5 1 0) of the present invention has an output of an operational amplifier (OPAMP: 4 1 3) used as a buffer compared to a conventional source driver (4 1 0). The first switch SW 1 is applied, and the output of the digital-to-analog converter (DAC: 4 1 2) is applied by the second switch SW 2 directly connected to the panel. The operation of the source driving circuit of the present invention shown in the fifth figure is described below with reference to the timing chart of the switch control signal not shown in the sixth figure. As shown in the sixth figure, 1 line time is divided into two phases (P h a s e), which are divided into the driving period of the operational amplifier and the digital analog converter (DAC) which directly drives the data line to compensate for the error. The first phase (phase) is the period when the first switch SW1 shown in the fifth figure is closed, and the period when the output of the operational amplifier (0PA MP) used as a buffer is connected to the data line of the panel. The second phase is the period when the second switch SW 2 shown in the fifth figure is closed, that is, the period when the output of the digital-to-analog converter DAC is directly connected to the data line of the panel. Thus, according to the LCD source driving method of the present invention, the voltage of the panel is charged by an operational amplifier (〇PA MP) used as a buffer between the first phase in which the first switch SW1 is closed. The voltage is slightly the same as the pre-represented voltage (that is, only

Page 11 521254 V. Description of the invention (8) Differential charging) a s e) * ^ Connected panel A MP P) According to the present invention, the in-and-out error has a high color level. [Invention t The above-mentioned households have time-divided into the power of the panel, and the direct drive has a six-bit effect. Also, while in the second room, it is possible to compensate for the input and output errors, even if L c D is the color effect to be expressed. As described above, in the rain stage of the present invention, the material line and the moving data line can be equal to each other. Use low

The switch s W 2 is closed in the second stage (the output of the Ph analog converter (DAC) is directly the error of the panel voltage generated by the operational amplifier (0p) used by the buffer. Therefore, the source drive circuit uses Where the error of the buffer level is large, it can also show that S is to apply one of the image signals to the data line Γ C is to calculate the output of the amplifier: White 'is compensated by a digital analog converter The error is that even a profitable computing amplifier can achieve high color gradation and low cost.

Page 12 521254 Brief description of the diagram The first diagram is a schematic diagram showing the equivalent circuit of a general TFT liquid crystal display device. The second diagram a is a schematic diagram illustrating the gradation display using the day-to-surface ratio adjustment (F R C) method. The second b diagram is an example of the color scale of the second a diagram. The third a is a graph showing the relationship between the driving voltage and the gradation display. Fig. 3b is an explanatory diagram showing the gradation display using the high-frequency vibration method. The fourth a is a block diagram of a conventional source driver. Figure 4b is a diagram illustrating an example of a conventional source driver. The fifth figure is a schematic diagram of the source driving circuit of the present invention. The sixth figure is a timing chart of the switch control signal during the source driving of the present invention. [Illustration of figure number] 110 ------ gate driver 12 0 ------ source driver 13 2 ------ thin film transistor 134 liquid crystal element 4 0 1 ------ Shift register 4 0 2 ------ Latching part 4 0 3 ------ Digital analog converter 4 0 4 --------- Output buffer 4 0 5 ------ Data latch

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Claims (1)

The scope of six patent applications shows that the source drive of the i-type liquid crystal display device is driven by the earth ^ y is the day cry of the source driver drive panel ::: The display device is equipped with digital-analog conversion; the method: It is characterized by: · Dividing the pair of converters and calculation magnification time into two stages, applying one of the image signals to the line to drive the data line of the driving panel: the white segment is the wheel of the converter of the calculation amplifier A direct-drive digital-analog conversion amplifier with a lower degree can also perform higher: Compensation error, even if 2 · a type of liquid crystal display image data is used to drive the source drive circuit of the liquid crystal display device, which is characterized by having There is a source drive circuit for _ ^ σ shell material line, its material;-Digital to analog conversion cry zone :: Department: The rotation of the aforementioned image information data into analog signals 叩 丄 = will be converted from the aforementioned digital area The output of the shadow of the block input-analog converter: and drive = 3: 'The buffering of the aforementioned number is located in the first period of the line time A a Bei line; a first switch, communicated to the foregoing Feed line; a Bi - 'will Ke said output of the calculation amplifier 〇N, the aforementioned digital class ~: based on the second time period of the data line rows. The output of the converter is directly connected to the aforesaid 3. If the patent application scope is the first moving circuit, it is characterized by the inch switch, the source drive of the display device on the day a, and when the aforementioned-switch is ON: When the relationship with the aforementioned second opening is OFF, the aforementioned second-second ... Page 521254 Page 16