CN1808551A - Gray-scale brightness compensation method and device thereof - Google Patents

Abstract

The invention relates to a gray scale brightness compensation device of a liquid crystal display, which mainly aims at compensating gray scale voltage values of a first horizontal Line with the same polarity when an N-Line conversion (N-Line Inversion) driving method is adopted by the liquid crystal display. The multiplexer is controlled by a control signal, and when the polarity is positive, the polarity control signal controls to output higher voltage in the first horizontal line time when the polarity is reversed; when the polarity is negative, the polarity control signal controls to output a lower voltage in the first horizontal line time when the polarity control signal is reversed.

Description

Gray-scale brightness compensation method and device thereof

technical field

The present invention relates to a display mode and device of gray-scale brightness, and in particular to an N-Line Inversion driving method adopted by a liquid crystal display, in which gray-scale brightness is compensated by gray-scale voltage The methods and devices to be used.

Background technique

In recent years, due to the advantages of light weight, thin size, large or small area, low operating voltage, power saving, and no radiation, liquid crystal display panels have gradually become the mainstream of display panels and are becoming more and more important.

For the liquid crystal display panel, because the liquid crystal molecules themselves have a characteristic, they cannot be fixed at a voltage of a specific polarity all the time. Otherwise, after a long time, even if the voltage is removed, the liquid crystal molecules will no longer be able to rotate with the change of the electric field because their characteristics have been destroyed. Therefore, for the liquid crystal display panel, even if the displayed picture does not change at regular intervals, the polarity of the voltage applied to the liquid crystal must still be changed to avoid damage to the properties of the liquid crystal molecules. In the existing liquid crystal display panel driving methods, the polarity conversion method is to divide the voltage difference applied to both ends of the liquid crystal molecules into two types: positive voltage difference and negative voltage difference, and the polarity conversion method includes: frame inversion (frame inversion) ), row inversion, column inversion, and dot inversion. Among the above conversion methods, the difference lies in whether the polarities between two adjacent pixels (pixels) on the LCD panel are the same or not, and the inversion of the polarity of each pixel is basically synchronized with the scanning of the entire panel image. . At present, because dot inversion is the least likely to cause problems of flicker and cross-talk, it is widely used.

Among the existing dot inversion methods, one-line inversion, two-line inversion, and N-line inversion have been developed, among which N The polarity distribution and scanning waveform of line conversion can be obtained by analogy with the polarity distribution and scanning waveform of double-line conversion.

FIG. 1 is a system architecture diagram of a conventional liquid crystal display source drive circuit. It includes: a latch 100 , a level changer 102 , a gamma resistor 104 , a digital-to-analog converter 108 and an output buffer 110 . Digital data is written into the latch 100. When the latch 100 stores image data of a horizontal line, the data will be output to the level changer 102 at the same time, and the level changer 102 will change the voltage level of the digital image data. The bit is then output to the digital to analog converter 108, the digital image data received by the digital to analog converter 108 will output the analog image data to the output buffer 110, and finally the output buffer 110 will write the image data into the liquid crystal, and wherein The output buffer 110 is composed of a single gain negative feedback operational amplifier.

Since the on-resistance of the thin film transistor (TFT) on the liquid crystal display panel is very large, the RC time constant for charging and discharging the pixels will also increase accordingly. As shown in the charge and discharge diagram of the pixel capacitor on the liquid crystal display in Figure 2, the charge and discharge of the charge does not directly reach the target voltage, so there will be an error voltage, resulting in the error voltage of the first horizontal line in the same polarity will be greater than that of the second Two subsequent horizontal lines. Taking a liquid crystal display with XGA resolution (1024×768) as an example, the writing time of each horizontal line is about 20μS. If the time constant of each pixel is 5μS, there will be about 1.8% error voltage. If it is 10 The error voltage is about 183mV in terms of the operating voltage of the liquid crystal in volts. For higher resolution LCDs, the resulting error voltage will be larger due to the shorter horizontal line time.

When the traditional driving circuit is used with the N-line conversion driving method, there will be the following disadvantages:

1. Since each gray level of the conventional driving circuit is equipped with a gamma resistor, the voltage of each gray level is a fixed value.

2. When using the N-line conversion driving method, although the purpose of power saving can be achieved, because the polarity needs to be reversed every N horizontal lines, it will cause the charging and discharging charges of two adjacent horizontal lines to be different, resulting in gray scale The displayed results are also different. So when the entire display displays the same grayscale value, you will see alternating light and dark stripes on the panel.

For the liquid crystal display panel, when the N-line conversion driving method is adopted, the driving circuit and method that can avoid problems such as alternating light and dark are particularly important.

Contents of the invention

The characteristic of the present invention is to provide a grayscale brightness compensation method, which can substantially eliminate one or more problems caused by limitations and inconveniences of the prior art.

The invention provides a gray scale brightness compensation method, which is suitable for a liquid crystal display panel. The liquid crystal display panel has a plurality of data lines and a plurality of horizontal lines perpendicular to the data lines arranged from top to bottom. The plurality of data lines There are many pixels, where each pixel generates corresponding gray-scale brightness according to the signal provided by the data line. The gray-scale voltage compensation method includes multiple gray-scale voltages for selection when corresponding to a certain gray-scale brightness. When the pixel When the charging and discharging time is insufficient, a voltage higher or lower than the target voltage can be selected to achieve the purpose of gray scale voltage compensation, and the selection method can be controlled by a control signal.

One embodiment of the present invention provides a grayscale brightness compensation mechanism. The method is that for the same grayscale brightness, when the pixel is positive, a control signal is provided to the pixel with insufficient charging time. The control signal can be controlled by multiple grayscales. Among the level voltages, a higher gray level voltage is selected for compensation, and the magnitude of the compensation voltage is determined by the error voltage.

One embodiment of the present invention provides a grayscale brightness compensation mechanism. The method is that for the same grayscale brightness, when the pixel is negative, a control signal is provided to the pixel with insufficient discharge time. The control signal can be controlled by multiple grayscales. Among the level voltages, a lower gray level voltage is selected for compensation, and the magnitude of the compensation voltage is determined by the error voltage.

Yet another embodiment of the present invention provides a gray-scale brightness compensation mechanism. The method is that when two adjacent horizontal lines of the same polarity display the same gray-scale brightness, according to the error voltage between the two horizontal lines, from multiple gray-scale Choose one of the voltages for compensation, and only compensate for the first horizontal line of the same polarity.

Yet another embodiment of the present invention provides a method for judging the error voltage required for gray-scale brightness compensation. The method is that when multiple horizontal lines are of the same polarity, the difference between the first horizontal line and the storage capacitors of the pixels on the remaining multiple horizontal lines Voltage, after the same horizontal line time, its voltage value difference.

Another embodiment of the present invention provides a liquid crystal display with a grayscale voltage compensation device, the liquid crystal display includes a liquid crystal display panel, a voltage divider circuit, a control signal generator, multiple multiplexers, and a digital-to-analog converter device. The liquid crystal display panel has a plurality of data lines and a plurality of horizontal lines arranged vertically from the top to the bottom of the data lines. Each data line has a plurality of pixels, and each pixel corresponds to a grayscale brightness. Each pixel At the same time, it also corresponds to a polarity signal. The voltage divider circuit is used to receive and divide multiple gamma voltages, and generate multiple gray scale voltages corresponding to the brightness of each gray scale. The control signal generator It is coupled to the data line, and generates a control signal according to the polarity of the data line, and the multiplexer is respectively coupled to the voltage divider circuit and the control signal generator, and according to the received control signal, from multiple gray scale voltages One of them is selected for compensation, and the digital-to-analog converter is connected to the multiplexer so as to receive the gray-scale voltage output by the multiplexer.

Yet another embodiment of the present invention provides a voltage dividing circuit, which is composed of multiple voltage dividing components connected in series, and each voltage dividing component can be composed of multiple active components or passive components.

Yet another embodiment of the present invention provides a voltage divider circuit. The n grayscale voltages that the voltage divider circuit needs to generate for the mth grayscale brightness are composed of m×n voltage divider components connected in series, and each voltage divider Components can consist of multiple active or passive components.

Another embodiment of the present invention provides a liquid crystal display with a grayscale voltage compensation device. When the pixel corresponding to the grayscale brightness of the liquid crystal display is positive, the control signal generator will control each multiplexer so that each A multiplexer selects a high gray-scale voltage from the corresponding multiple gray-scale voltages and outputs it to the digital-to-analog converter for compensation.

Another embodiment of the present invention provides a liquid crystal display with a grayscale voltage compensation device. When the pixel corresponding to the grayscale brightness of the liquid crystal display is negative, the control signal generator will control each multiplexer so that each A multiplexer selects a low gray-scale voltage from the corresponding multiple gray-scale voltages and outputs it to the digital-to-analog converter for compensation.

Yet another embodiment of the present invention provides a liquid crystal display driving method that requires grayscale voltage compensation. The driving method is an N-line conversion driving method, that is, the polarity of N horizontal lines is reversed once, and the N value is greater than or equal to 2.

Description of drawings

FIG. 1 shows a schematic diagram of a traditional liquid crystal display source drive circuit system;

FIG. 2 shows a charge and discharge diagram of a pixel capacitor of a liquid crystal display;

FIG. 3 shows the structure diagram of the improved source drive circuit system of the present invention;

FIG. 4A is a schematic diagram of a gamma resistor of a conventional source driving circuit;

FIG. 4B shows a realization diagram of an improved gamma resistor;

FIG. 5A shows a realization diagram of the gray scale compensation circuit when the polarity is positive;

FIG. 5B shows the implementation diagram of the gray scale compensation circuit when the polarity is negative;

FIG. 6A shows a realization diagram of the gray scale compensation circuit connected to the multiplexer when the polarity is positive;

FIG. 6B is a diagram showing the implementation of the gray scale compensation circuit connected to the multiplexer when the polarity is negative;

Figure 7 shows the control circuit timing diagram.

Detailed ways

Preferred features of selected embodiments of the invention will be described with reference to the drawings. The spirit and scope of the present invention are not limited to these examples chosen for illustration. It is worth noting that these drawings should not be considered to any particular size or scale. Any structures and materials described below may be appropriately modified within the scope of the present invention.

If the traditional driving circuit is used with the dot conversion driving method, since the polarities of two adjacent horizontal lines need to be reversed, although there is an error voltage in the charging and discharging voltages of all pixels, when the entire screen displays the same gray scale, the human eye will not be able to see it. It is not easy to detect the existence of the error voltage from the results displayed on the monitor, and a clear picture can still be seen.

But in practice, we don't need to achieve the degree of point conversion, so the present invention adopts a more power-saving N-line conversion driving method, and when using the N-line conversion driving method, the first gray line of the same polarity Method and device for compensating step voltage value.

The liquid crystal display panel has a plurality of data lines and a plurality of horizontal lines perpendicular to the data lines arranged from top to bottom. The data line has a plurality of pixels, and each pixel corresponds to a gray scale brightness and a polarity signal. When the N-line conversion drive mode is matched with the traditional drive circuit, the polarity needs to be reversed only once during the time of N horizontal lines, and the charge and discharge charges of two adjacent horizontal lines with the same polarity are different due to the characteristics of the circuit. Therefore, for N -Line Inversion driving method, the present invention adopts the method of compensating the gray scale voltage value of the first horizontal line within the same polarity.

Referring to FIG. 3 , different from the structure diagram of the existing source drive circuit system, the structure diagram of the source drive circuit system of the present invention includes: a latch 300, a level changer 302, a gamma resistor 304, multiple task processor 306 , digital-to-analog converter 308 and output buffer 310 . The digital data is written into the latch 300. When the latch 300 stores a horizontal line of image data, the data will be synchronously output to the level changer 302, and the level changer 302 will change the voltage of the digital image data. The level is then output to the digital-to-analog converter 308, the digital-to-analog converter receives the digital image data and then outputs the analog image data to the output buffer 310, and finally the output buffer 310 writes the image data into the liquid crystal, and the The output buffer 310 is composed of a single gain negative feedback operational amplifier.

Different from the schematic diagram of gamma resistance on the existing source drive circuit, as shown in FIG. 4A , the present invention improves the system architecture of the traditional source drive, and subdivides the gamma resistance of each gray scale into n resistor, and FIG. 4B is a schematic diagram of the improved Gamma resistor when n=2. Comparing Fig. 4A and Fig. 4B, it can be seen that the respective resistance relationships are that R1 in Fig. 4A is equivalent to R1a+R1b in Fig. 4B, R2 in Fig. 4A is equivalent to R2a+R2b in Fig. 4B, and Rm in Fig. 4A is equivalent to Rma+Rmb in Figure 4B. Wherein m can be any integer, but in the case of N-line conversion, m=2N-1 is usually set. In order to achieve the purpose of compensation, Rma and Rmb are selected so that the gray scale voltages of two adjacent horizontal lines of the same polarity are the same.

FIG. 5A is an implementation diagram of a gray scale compensation circuit for a liquid crystal display when the polarity is positive. When the polarity control signal is reversed for the first horizontal line time, the control signal generator 500 controls the multiplexer 502 to output a relatively high voltage, and the other horizontal line time control signal generator 500 controls the multiplexer 502 to output a relatively high voltage. lower voltage.

FIG. 5B is an implementation diagram of a gray scale compensation circuit for a liquid crystal display when it is in negative polarity. When the first horizontal line of the polarity control signal is reversed, the control signal generator 510 controls the multiplexer 512 to output a relatively low voltage, and the other horizontal line time control signal generator 510 of the same polarity controls the multiplexer 512 to output a relatively low voltage. higher voltage.

When two adjacent pixels display the same gray-scale brightness under the same polarity, the appropriate gray-scale voltage Vm is selected according to the error voltage Ve generated by the difference in the charge stored in the storage capacitor on the two adjacent pixels, and only for the same polarity Compensate for the first horizontal line of the sexual signal. The error voltage Ve is the voltage difference between the first horizontal line and the rest of the horizontal lines in the same polarity signal within the writing time for the same horizontal line. When the error voltage Ve is greater than the gray-scale voltage difference of the two adjacent levels, the division result of the gray-scale voltage Vk of the k-th level can be selected to compensate the gray-scale voltage of the first horizontal line at the same polarity. In positive polarity, V(k+1)<Vm+Ve<Vk, Figure 6A is a realization diagram of one of the gray scale compensation circuits connected to the multiplexer; in negative polarity, V(k+1)<Vm- Ve<Vk, FIG. 6B is an implementation diagram of one gray scale compensation circuit connected to a multiplexer.

Each gray-scale luminance corresponds to a multiplexer, and the multiplexer selects one of the gray-scale voltages as corresponding to a certain gray-scale luminance so as to be output to the digital-to-analog converter. The multiplexer is controlled by a control signal generator, the timing diagram of the control signal is shown in Figure 7, so that the first horizontal line of the same polarity can be selected for compensation.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention shall be defined by the scope of the appended patent application.

Claims (22)

1. grayscale brightness compensation method, be applicable to a display panels, most bar horizontal lines that this display panels has most bar data lines and from top to bottom arranges in regular turn perpendicular to those data lines, each those data line all has most pixels, each those data line provides a signal to make each affiliated those pixel produce a corresponding GTG brightness, it is characterized in that this gray scale voltage compensation method comprises:

Generation is corresponding to most gray scale voltages of this GTG brightness; And

Receive a control signal and in those gray scale voltages, select one of them to compensate according to this control signal.

2. grayscale brightness compensation method as claimed in claim 1, it is characterized in that, when pairing this pixel of this GTG brightness is a positive polarity, each those pixel for the duration of charging deficiency provide this control signal, this control signal can be by in those gray scale voltages, select a high gray voltage to compensate, the size of bucking voltage is determined by an error voltage.

3. grayscale brightness compensation method as claimed in claim 1, it is characterized in that, when pairing this pixel of this GTG brightness is a negative polarity, each those pixel of deficiency provide this control signal for discharge time, this control signal is by in those gray scale voltages, select a low gray scale voltage to compensate, the size of bucking voltage is determined by an error voltage.

4. grayscale brightness compensation method as claimed in claim 1, it is characterized in that, when adjacent two horizontal lines of a same polarity show a same gray level brightness, according to these two horizontal error voltages, among those gray scale voltages, select one of them to compensate, and only article one horizontal line of this same polarity is compensated.

5. grayscale brightness compensation method as claimed in claim 4, it is characterized in that, when this same polarity of most bar horizontal lines place, this error voltage is those pixel storage capacitors on article one horizontal line and all the other those horizontal lines, the magnitude of voltage that is had respectively, passed through one of identical horizontal line after the time, one voltage value difference.

6. grayscale brightness compensation method as claimed in claim 1 is characterized in that, a driving method of this display panels that is suitable for is a N line conversion driving method, i.e. N bar horizontal line reversal of poles once, and this N value is more than or equal to 2.

7. grayscale brightness compensation device, be applicable to a display panels, most bar horizontal lines that this display panels has most bar data lines and from top to bottom arranges in regular turn perpendicular to those data lines, each those data line has most pixels, each those pixel corresponds to one of them of most GTG brightness again, each those pixel also corresponds to a polar signal, it is characterized in that, this gray scale voltage compensation system comprises:

One bleeder circuit is made dividing potential drop in order to receive to reach to most gamma voltages, and produces the most individual gray scale voltages corresponding to each those GTG brightness;

One control signal generator is coupled to those data lines, in order to produce a control signal according to one of those data lines polarity;

A most multiplexer are coupled to this bleeder circuit and this control signal generator, receive this control signal and select one of them to compensate in those gray scale voltages according to this control signal; And

One digital to analog converter is coupled to those multiplexers, in order to receive those gray scale voltages by those multiplexer outputs.

8. grayscale brightness compensation device as claimed in claim 4 is characterized in that, described this bleeder circuit is in series by most dividing potential drop assemblies, and each those dividing potential drop assembly is made up of most passive components.

9. grayscale brightness compensation device as claimed in claim 4 is characterized in that, described this bleeder circuit is in series by most dividing potential drop assemblies, and each those dividing potential drop assembly is made up of most driving components.

10. grayscale brightness compensation device as claimed in claim 7, it is characterized in that, for those gray scale voltages of one second quantity of the required generation of those GTG brightness of each first quantity is to be in series by most the dividing potential drop assemblies that this first quantity is multiplied by this second quantity, and each those dividing potential drop assembly is made up of most passive components.

11. grayscale brightness compensation device as claimed in claim 7, it is characterized in that, for those gray scale voltages of one second quantity of the required generation of those GTG brightness of each first quantity is to be in series by most the dividing potential drop assemblies that this first quantity is multiplied by this second quantity, and each those dividing potential drop assembly is made up of most driving components.

12. grayscale brightness compensation device as claimed in claim 7, it is characterized in that, when pairing this pixel of this GTG brightness is a positive polarity, this control signal generator is just controlled each those multiplexer, make each those multiplexer by among corresponding those gray scale voltages that receive, select a high gray voltage, and export this digital to analog converter to and compensate.

13. grayscale brightness compensation device as claimed in claim 7, it is characterized in that, when pairing this pixel of this GTG brightness is a negative polarity, this control signal generator is just controlled each those multiplexer, make each those multiplexer by among corresponding those gray scale voltages that receive, select a low gray scale voltage, and export this digital to analog converter to and compensate.

14. grayscale brightness compensation device as claimed in claim 7 is characterized in that, one of this display panels that is suitable for driving method is a N line conversion driving method, i.e. N bar horizontal line reversal of poles once, and this N value is more than or equal to 2.

15. a LCD has a gray scale voltage compensation system, it is characterized in that, comprising:

One display panels, most bar horizontal lines that this display panels has most bar data lines and from top to bottom arranges in regular turn perpendicular to those data lines, each those data line has most pixels, each those pixel corresponds to one of them of most GTG brightness again, and each those pixel also corresponds to a polar signal;

One bleeder circuit is made dividing potential drop in order to receive to reach to most gamma voltages, and produces the most individual gray scale voltages corresponding to each those GTG brightness;

One control signal generator is coupled to those data lines, in order to produce a control signal according to one of those data lines polarity;

A most multiplexer are coupled to this bleeder circuit and this control signal generator, receive this control signal and select one of them to compensate in those gray scale voltages according to this control signal; And

One digital to analog converter is coupled to those multiplexers, in order to receive those gray scale voltages by those multiplexer outputs.

16. LCD as claimed in claim 15 is characterized in that, described this bleeder circuit is in series by most dividing potential drop assemblies, and each those dividing potential drop assembly is made up of most passive components.

17. LCD as claimed in claim 15 is characterized in that, described this bleeder circuit is in series by most dividing potential drop assemblies, and each those dividing potential drop assembly is made up of most driving components.

18. LCD as claimed in claim 15, it is characterized in that, for those gray scale voltages of one of the required generation of those GTG brightness of each first quantity second quantity is to be in series by most the dividing potential drop assemblies that this first quantity is multiplied by this second quantity, and each those dividing potential drop assembly is made up of most passive components.

19. LCD as claimed in claim 15, it is characterized in that, for those gray scale voltages of one of the required generation of those GTG brightness of each first quantity second quantity is to be in series by most the dividing potential drop assemblies that this first quantity is multiplied by this second quantity, and each those dividing potential drop assembly is made up of most driving components.

20. LCD as claimed in claim 15, it is characterized in that, when pairing this pixel of this GTG brightness is a positive polarity, this control signal generator is just controlled each those multiplexer, make each those multiplexer by among corresponding those gray scale voltages that receive, select a high gray voltage, and export this digital to analog converter to and compensate.

21. LCD as claimed in claim 15, it is characterized in that, when pairing this pixel of this GTG brightness is a negative polarity, this control signal generator is just controlled each those multiplexer, make each those multiplexer by among corresponding those gray scale voltages that receive, select a low gray scale voltage, and export this digital to analog converter to and compensate.

22. LCD as claimed in claim 15 is characterized in that, described driving method is a N line conversion driving method, i.e. N bar horizontal line reversal of poles once, and this N value is more than or equal to 2.

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