CN102820014A - Driving method and driving circuit for liquid crystal display, and liquid crystal display - Google Patents

Abstract

Embodiments of the present invention provide a driving method, a driving circuit, and a liquid crystal display for a liquid crystal display. The method includes dividing the time of any frame into two operating time periods in a row inversion or dot inversion driving mode; In the above operation time period, turn on the scan lines of odd rows in sequence, write the data signals of odd rows into pixels in odd rows, and in the other operation time period, turn on the scan lines of even rows in sequence, and write the data signals of even rows into even row of pixels. The odd-numbered scanning lines and the even-numbered scanning lines of the liquid crystal display are driven separately. Since each driving is completed within half the length of one frame, the load capacitance of the pixel does not need to be completed within an operation period. The conversion from positive voltage to negative voltage only completes the conversion from positive voltage or negative voltage to reference level at most. Therefore, according to the power consumption formula, it can be known that the power consumption of the data logic of the liquid crystal display is reduced.

Description

Liquid crystal display driving method, driving circuit and liquid crystal display

technical field

The invention relates to liquid crystal display technology, in particular to a driving method, a driving circuit and a liquid crystal display for a liquid crystal display.

Background technique

Power consumption is an important performance index of liquid crystal displays, and an important component of it is the logic power consumption of data signals.

In liquid crystal displays, common storage capacitors include gate storage capacitors (Cs on gate) and common storage capacitors (Cs on common). The storage capacitor is routed using the common electrode. Each thin-film transistor (TFT) is connected to the storage capacitor Cst, which represents a display point. A basic display unit (pixel) needs three such points to represent the three primary colors of red (R), green (G), and blue (B). ; A thin film transistor liquid crystal display (TFT LCD) with a resolution of 1024×768 needs 1024×768×3 such points in total. With the waveform sent by the gate driver, the TFTs of each row are turned on in sequence, so that the source driver of the whole row can charge the points of a whole row to their respective required voltages at the same time, displaying different gray scale. When the charging of this row is completed, the gate driver will turn off the voltage, then the gate driver of the next row will turn on the voltage, and then the same row of source drivers will charge the points of the next row; in this order, when After charging the point of the last row, it starts charging again from the first row. A LCD with a resolution of 1024×768 has a total of 768 lines of gate lines, 1024×3=3072 lines of source lines; an LCD with an update frequency of 60Hz, the display time of each screen is about 1/60=16.67 ms, since the composition of the screen is 768 rows of gate lines, the switching time allocated to each gate line is about 16.67ms/768=21.7μs, and the source driver drives the pixel electrode within 21.7μs Charge and discharge to the required voltage and display the corresponding gray scale.

The display voltage in the liquid crystal display is divided into two polarities, one positive polarity and one negative polarity; the voltage of the pixel electrode is higher than the voltage of the common electrode, which is called positive polarity, and the voltage of the pixel electrode is lower than the voltage of the common electrode, called It is negative polarity; both positive and negative polarity will have a set of gray scales with the same brightness. Therefore, when the absolute value of the voltage difference between the upper and lower electrodes is fixed, no matter whether the voltage of the pixel electrode is high or the voltage of the common electrode is high, the displayed gray scale is exactly the same. However, the directions of the liquid crystal molecules in these two cases are completely opposite. By continuously inverting, the characteristic damage caused when the liquid crystal molecules are always fixed in one direction can be avoided. In other words, when the display screen is not moving all the time, it is still possible to achieve the result that the display screen does not move while the characteristics of the liquid crystal molecules are not destroyed by continuously alternating positive and negative polarities. Existing implementations of inversion include frame inversion, row inversion, column inversion, dot inversion, and the like.

As shown in FIG. 1 , there is a storage capacitor Cst and a load capacitor C between the pixel electrode and the common electrode. The power consumption formula of the data signal is P=Cf(ΔV) ² , where the magnitude of the load capacitance C and the change frequency f of the data signal are constant. For the existing implementations of row inversion and dot inversion, within one frame, the voltage applied to both ends of the storage capacitor Cst frequently changes between positive voltage Vp and negative voltage Vn, ΔV=Vp-Vn; positive The absolute values of the voltage Vp and the negative voltage Vn are substantially the same.

In order to reduce logic power consumption, in some prior art, the external memory of the embedded chip is disabled, and only the on-chip RAM is used to access image data and codes. Or, in some existing technologies, the bistable chiral nematic liquid crystal is first driven to a preset initial state, and then the grayscale image data to be updated is written into the pixel, and then the applied voltage of the pixel is reset to zero, so that Restoring the bistable chiral nematic liquid crystal to a stable state corresponding to the grayscale picture data written.

The following problems exist in the prior art: in the process of writing data signals to the liquid crystal display, the voltage of the load capacitor needs to be frequently switched between positive and negative voltages, resulting in excessive power consumption for writing data signals.

Contents of the invention

The present invention aims to provide a driving method, a driving circuit and a liquid crystal display for a liquid crystal display, which are used to solve the problem that in the prior art, in the process of writing data signals to the liquid crystal display, the voltage of the load capacitor needs to be frequently between positive and negative voltages. The ground is switched, resulting in the defect that the power consumption of the write data signal is too large.

In order to solve the above-mentioned technical problems, an embodiment of the present invention provides a driving method of a liquid crystal display, including: in the line inversion or dot inversion driving method, dividing the time of any frame into two operation time periods; In one of the operation time periods, the scan lines of the odd rows are turned on sequentially, and the data signals of the odd rows are written into the pixels of the odd rows; even-numbered rows of pixels.

In the method, the sequentially opening the odd-numbered scanning lines includes: sequentially scanning each odd-numbered scanning line from the top to the bottom of the liquid crystal display; and sequentially opening the even-numbered scanning lines includes: starting from the liquid crystal display Each even-numbered scan line is scanned sequentially from the top to the bottom.

In the method, when there are more than one odd row scanners connected to each of the odd row scan lines, each of the odd row scanners is sequentially driven, and each of the odd row scanners sequentially opens its own connection The odd-numbered scanning lines to write the odd-numbered data signals to the corresponding odd-numbered pixels; when there are more than one even-numbered row scanners connected to each of the even-numbered scanning lines, drive each of the even row scanners, each of the even row scanners sequentially turns on the even row scanning lines connected to itself to write even row data signals to the corresponding even row pixels.

In the method, in one operating time period, a counter is used to count the scanning operations performed by each of the odd row scanners; in another operating time period, the counter is used to count Count the scanning operations performed by the even-numbered row scanners.

In the method, in one operation time period, each time the counter counts once, one scan operation is performed corresponding to one of the odd-numbered row scanners, and all the odd-numbered row scanners are operated within the operation time period. Executing a scanning operation; in another operating time period, each time the counter counts once, corresponding to one of the even-numbered row scanners performing a scanning operation, and making all the even-numbered row scanners perform during the operating time period scan operation.

A driving circuit, which drives a liquid crystal display in a row inversion or dot inversion mode, the driving circuit includes: a scanning logic unit, used to divide the time of one frame into two operating time periods; an odd row scanner, used to In one of the operation time periods, the odd-numbered scan lines are turned on sequentially, and the odd-numbered row data signals are written into odd-numbered pixels; the even-numbered row scanner is used to turn on the even-numbered scan lines in turn during another said operation time period , write the data signal of the even row into the pixels of the even row.

In the drive circuit, there are more than one odd row scanner and/or even row scanner, and the drive circuit further includes: a counter for each of the odd row scanners within one operation period. The scanning operations performed by the row scanners are counted, and the scanning operations performed by each of the even-numbered row scanners are counted during another operation time period.

In the drive circuit, the counter further includes: a frequency multiplication module, configured to set the count of the counter within one operating time period, so that each count corresponds to one of the odd row scanners Execute a scan operation, and make all the odd-numbered row scanners perform a scan operation in this operation period; and in another operation period, set the count of the counter so that each count corresponds to a The even-numbered row scanners perform scanning operations, and all the even-numbered row scanners perform scanning operations during the operation period.

A liquid crystal display, including a driving circuit, the driving circuit drives the liquid crystal display in a row inversion or point inversion mode, and the driving circuit includes: a scanning logic unit, which is used to divide the time of one frame into two operating time periods; an odd number The line scanner is used to turn on the odd-numbered scanning lines sequentially during one of the operation time periods, and write the odd-number row data signals into odd-number rows of pixels; The scan lines of the even rows are turned on sequentially, and the data signals of the even rows are written into the pixels of the even rows.

The beneficial effects of the above-mentioned technical solution of the present invention are as follows: the odd-numbered scanning lines and the even-numbered scanning lines of the liquid crystal display are respectively driven. The load capacitor does not need to frequently complete the conversion from positive voltage to negative voltage during an operation period, but only completes the transition between positive voltages or negative voltages (at most from positive voltage or negative voltage to reference level) Therefore, according to the power consumption formula, it can be known that the power consumption of the data logic of the liquid crystal display is reduced.

Description of drawings

FIG. 1 shows a schematic structural diagram of a pixel;

Figure 2 shows a schematic diagram of the connection between the scan line and the IC;

Fig. 3 shows a schematic flow chart of a method for displaying data signals on a liquid crystal display;

Fig. 4 shows a schematic diagram of scanning operation in an operation time period;

FIG. 5 shows a schematic diagram of connections between multiple row scan lines and multiple ICs;

FIG. 6 shows a sequence diagram of performing multiple scanning operations in two operating time periods;

Fig. 7 represents the schematic diagram of the drive that completes in the half length of the time of one frame;

Odd scan line 1

Even scan lines 2

Load Capacitance 3

storage capacitor 4

Data cable 5

Gate line 6

Common electrode 7

Pixel electrode 8

Thin Film Transistor 9

Source 10.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

As shown in Figure 1, the structure of the pixel includes a load capacitor 3, a storage capacitor 4, a data line 5, a gate line 6, a common electrode 7, a pixel electrode 8, a thin film transistor 9, and a source 10; but it should be understood that the The source 10 is only schematic, in practice, for the thin film transistor 9, the source/drain can be interchanged.

As shown in Figure 2, the scanning lines of the panel are divided into odd-numbered scanning lines 1 and even-numbered scanning lines 2, both of which are connected to the integrated circuit (IC) to drive the odd-numbered and even-numbered lines of the panel separately, including: the odd-numbered scanning lines 1 is connected to the gate drive IC1, and the even-numbered scan line 2 is connected to the gate drive IC2. The gate driver IC1 is an odd row scanner, and the gate driver IC2 is an even row scanner.

An embodiment of the present invention provides a method for displaying a data signal on a liquid crystal display, as shown in FIG. 3 , the method includes:

Step 301, in the line inversion or dot inversion driving mode, divide the time of any frame into two operation time periods;

Step 302, within one operation time period, turn on odd-numbered scanning lines 1 sequentially, and write odd-numbered row data signals into odd-numbered rows of pixels,

And in another said operation period, turn on the scanning lines 2 of the even rows in sequence, and write the data signals of the even rows into the pixels of the even rows.

Apply the provided technical scheme to drive the odd-numbered scanning lines 1 and the even-numbered scanning lines 2 of the liquid crystal display respectively, since each driving is completed within half the length of one frame, as shown in Figure 7 It shows that the load capacitor 3 of the pixel does not need to complete the conversion from positive voltage to negative voltage within an operation period, but only completes the conversion between positive voltages or between negative voltages (at most, from positive voltage or negative voltage to reference voltage) Level) conversion, so according to the power consumption formula, it can be known that the power consumption of the data logic of the liquid crystal display is reduced. The time of one frame is divided into two equal parts to form two operation time periods of one frame. After the equal parts, in each operation time period, odd-numbered scanning lines 1 and even-numbered scanning lines 2 are respectively driven. The odd row data signal or the even row data signal is a pulse scanning signal; wherein, the pulse scanning signal is higher than the reference level, or lower than the reference level.

Of course, those skilled in the art should understand that when the total number of scanning lines is odd rather than even, it is sufficient to divide the time of one frame according to the ratio of odd and even lines, and it is not required to be accurately divided into two.

In a preferred embodiment, as shown in FIG. 4, step 302 specifically includes:

The sequentially opening the odd-numbered scan lines 1 includes: sequentially scanning each odd-numbered scan line 1 from the top to the bottom of the liquid crystal display;

The sequentially turning on the even-numbered scanning lines 2 includes: sequentially scanning each even-numbered scanning line 2 from the top to the bottom of the liquid crystal display.

In other words, the data signal is divided into two parts within one frame, one part corresponds to the pixel electrodes 8 of the odd rows, and the other part corresponds to the pixel electrodes 8 of the even rows; in the first half frame time, write the corresponding odd row data , and write the corresponding even row data in the second half frame time.

The power consumption formula of the load capacitor 3 is P=Cf(ΔV) ² , where the load capacitor 3 and the signal change frequency are determined. By adopting the technique of the above embodiment, the change value ΔV of the data signal within half a frame time is greatly reduced compared with the dot inversion implementation in the prior art, thus reducing the power consumption of the data logic.

Apply the provided technology in an application scenario, including:

Step 1, divide the time of one frame into two equal parts to form two operation time periods, and each operation time period is half a frame time;

Step 2, as shown in Figure 5, for the first half of the frame, for example, set the counter to 0, the odd-numbered row scanner sequentially scans each odd-numbered row scanning line 1 connected to itself, and the system writes the odd-numbered row data signal to the odd-numbered row of pixels,

Step 3, for the second half frame, set the counter to 1, the even-numbered row scanner scans each even-numbered scanning line 2 connected to itself, and the system writes the even-numbered row data signal to the even-numbered row pixels.

In other words, by switching the value of the counter between 0 and 1, it is possible to switch whether to write data signals to pixels in odd rows or pixels in even rows; the same cycle operation can also be performed for subsequent frames.

As shown in FIG. 5 , there may be more than one odd row scanner connected to each of the odd row scan lines 1 , or more than one even row scanner connected to each of the even row scan lines 2 .

In a preferred embodiment, when there are more than one odd-numbered row scanners connected to each of the odd-numbered row scanning lines 1, each of the odd-numbered row scanners is sequentially driven, and each of the odd-numbered row scanners is sequentially turned on. The odd-numbered scanning lines 1 connected to themselves are used to write the odd-numbered row data signals to the corresponding odd-numbered pixels;

When there are more than one even-numbered row scanners connected to each of the even-numbered row scanning lines 2, each of the even-numbered row scanners is driven sequentially, and each of the even-numbered row scanners turns on the even-numbered rows connected to itself in turn. The scanning line 2 is used to write even-numbered row data signals to corresponding even-numbered row pixels.

When the panel of the liquid crystal display is large and the resolution is high, the odd-numbered scanning lines 1 and the even-numbered scanning lines 2 can be divided again, and the odd-numbered scanning lines 1 are connected to a plurality of gate drive IC1s (odd-numbered scanning lines ), the even-numbered scanning lines 2 are connected to a plurality of gate drive IC2s (even-numbered scanners); during the scanning process, each odd-numbered scanning line 1 is still charged in turn first, and then each even-numbered scanning line 2 is charged.

In a preferred embodiment, a counter is used to count the scanning operations performed by each of the odd row scanners within one operating time period;

In another said operation period, the counter is used to count the scanning operations performed by each of the even-numbered row scanners.

In the time of one frame, a counter is used to count the scanning operations performed by each scanner in each operation time period in a cycle.

According to the number of odd row scanners and even row scanners, the counting bits of the counter are set to count the multiplied frequency of the control signal output by the counter, such as the vertical signal start pulse (STVP), and the STVP is the logic of TFT LCD signal on one pin of the driver.

In a preferred embodiment, in one operation time period, each time the counter counts one time, one of the odd row scanners performs a scanning operation, and all the odd row scanners are operated during the operation time period. Perform scan operations within;

In another operation period, each time the counter counts one time, one of the even row scanners performs a scan operation, and all the even row scanners perform a scan operation in the operation period.

As shown in FIG. 6, within an operation time period, the odd-numbered row scanners perform scanning operations according to timing, and sequentially send scanning signals S _G1 , S _G3 , S _G5 , . . . , and S _G2n-1 ;

If the number of odd-numbered row scanners is more than one, that is, the above-mentioned scanning signals are respectively sent by each odd-numbered row scanner to turn on the TFT and receive data signals from the corresponding data lines, within an operation period, all odd-numbered row The scanner should complete sending the scanning signal;

In another said operation time period, the even-numbered row scanner performs scanning operation according to timing, and sends out scanning signals S _G2 , S _G4 , S _G6 , . . . , and S _G2n in sequence;

If the number of even-numbered row scanners is more than one, that is, the above-mentioned scanning signals are sent out respectively by each even-numbered row scanner to turn on the TFT and receive data signals from corresponding data lines, during this another operating period, all The even-numbered row scanners should finish sending out scanning signals. Applying the provided technology, in an application scenario, there are more than one odd-numbered line scanners and more than one even-numbered line scanners; taking a liquid crystal display with a resolution of 1024×768 as an example, there are 768/2= There are 384, and there are 768/2=384 scanning lines 2 in even rows.

Without loss of generality, if one scanner is connected to 32 scanning lines, there are 12 odd-numbered line scanners and 12 even-numbered line scanners.

Divide the time of one frame equally to form 2 operation time periods, and each operation time period is divided into 12 sub-operation time periods, each sub-operation time period is 1/24 of a frame time, and is assigned to a scanner;

The counter is able to record a total of 12+12=24 numbers.

include:

In step 1, during the process of the counter counting from 0 to 11, the counter sequentially drives each odd-numbered row scanner, and each odd-numbered row scanner sequentially drives the odd-numbered row scanning line 1 connected to itself. in,

When the count is 0, write the data signal to the odd-numbered pixels connected to the first odd-numbered scanning line 1;

When the count is 1, write the data signal to the odd-numbered row pixels connected to the second odd-numbered row scanning line 1;

By analogy, until the count is 11, write data signals to the odd-numbered pixels connected to the 12th odd-numbered scanning line 1;

The first half of a frame's time ends.

Step 2, during the process of the counter counting from 12 to 23, the counter sequentially drives each even-numbered row scanner, and each even-numbered row scanner sequentially drives the even-numbered row scanning line 2 connected to itself. in,

When the count is 12, write the data signal to the first even-numbered row of pixels;

When the count is 13, write the data signal to the second even-numbered row of pixels;

By analogy, until the count is 23, the data signal is written to the 12th even-numbered row of pixels;

The second half of the frame time ends.

An embodiment of the present invention also provides a driving circuit, which drives a liquid crystal display in a row inversion or dot inversion mode, and the driving circuit includes:

The scanning logic unit is used to divide the time of one frame into two operation time periods;

Odd-numbered row scanners, used to sequentially turn on odd-numbered row scan lines 1 within one operating time period, and write odd-numbered row data signals into odd-numbered row pixels;

The even-numbered row scanner is used to turn on the even-numbered row scanning lines 2 in turn during another operating time period, and write the even-numbered row data signals into the even-numbered row of pixels.

In a preferred embodiment, there are more than one odd row scanner and/or even row scanner, and the driving circuit further includes:

a counter, used to count the scanning operations performed by each of the odd row scanners during one operation period, and count the scanning operations performed by each of the even row scanners during another operation period The scan operations performed are counted.

In a preferred embodiment, the counter also includes:

The frequency multiplication module is used to set the count of the counter in one operation time period, so that each time the count corresponds to one of the odd row scanners to perform a scanning operation, and make all the odd row scanners perform scan operations during that operational time period; and

In another said operation period, the count of said counter is set, so that each said count corresponds to one said even-numbered row scanner performing a scan operation, and all said even-numbered row scanners are in this operation period Execute the scan operation.

An embodiment of the present invention also provides a kind of liquid crystal display, as shown in Figure 2, comprises driving circuit, and driving circuit comprises:

The scanning logic unit is used to divide the time of one frame into two operation time periods;

Odd-numbered row scanners, used to sequentially turn on odd-numbered row scan lines 1 within one operating time period, and write odd-numbered row data signals into odd-numbered row pixels;

The even-numbered row scanner is used to turn on the even-numbered row scanning lines 2 in turn during another operating time period, and write the even-numbered row data signals into the even-numbered row of pixels.

In a preferred embodiment, also include:

a counter, used to count the scanning operations performed by each of the odd row scanners during one operation period, and count the scanning operations performed by each of the even row scanners during another operation period The scan operations performed are counted.

In a preferred embodiment, the counter also includes:

The frequency multiplication module is used to set the count of the counter in one operation time period, so that each time the count corresponds to one of the odd row scanners to perform a scanning operation, and make all the odd row scanners perform scan operations during that operational time period; and

In another said operation period, the count of said counter is set, so that each said count corresponds to one said even-numbered row scanner performing a scan operation, and all said even-numbered row scanners are in this operation period Execute the scan operation.

The advantage after adopting this scheme is: within one-half of the time of one frame, turn on the odd-numbered scanning line 1 or the even-numbered scanning line 2 of the liquid crystal display, because each opening is half the time of one frame Completed within one length, the load capacitor 3 of the pixel does not need to complete the conversion from positive voltage to negative voltage in an operation period, but only needs to complete the conversion from positive voltage or negative voltage to the reference level, so it can reduce The power consumption of the data logic of the LCD.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be considered as falling within the protection scope of the present invention.

Claims (9)

1. a driving method of liquid crystal display, it is characterized in that, the method comprises: In the line inversion or dot inversion driving method, the time of any frame is divided into two operation periods; In one of the operation time periods, the scan lines of odd rows are turned on sequentially, and the data signals of odd rows are written into the pixels of odd rows; Write even row pixels. 2. The method of claim 1, wherein, The sequentially opening the odd-numbered scan lines includes: sequentially scanning each odd-numbered scan line from the top to the bottom of the liquid crystal display; The sequentially turning on the even-numbered scan lines includes: sequentially scanning each even-numbered scan line from the top to the bottom of the liquid crystal display. 3. The method of claim 2, wherein, When there are more than one odd-numbered row scanners connected to each of the odd-numbered row scanning lines, each of the odd-numbered row scanners is sequentially driven, and each of the odd-numbered row scanners sequentially turns on the odd-numbered row scanning connected to itself line to write the odd-numbered row data signal to the corresponding odd-numbered row of pixels; When there are more than one even-numbered row scanners connected to each of the even-numbered row scanning lines, each of the even-numbered row scanners is sequentially driven, and each of the even-numbered row scanners sequentially turns on the even-numbered row scanning connected to itself line to write even row data signals to the corresponding even row pixels. 4. The method of claim 3, wherein, In one operation period, a counter is used to count the scanning operations performed by each of the odd row scanners; In another said operation period, the counter is used to count the scanning operations performed by each of the even-numbered row scanners. 5. The method of claim 4, wherein, In one operation time period, each time the counter counts once, one of the odd row scanners performs a scanning operation, and all the odd row scanners perform a scanning operation in the operation time period; In another operation period, each time the counter counts one time, one of the even row scanners performs a scan operation, and all the even row scanners perform a scan operation in the operation period. 6. A drive circuit, which drives a liquid crystal display in a row inversion or point inversion mode, is characterized in that the drive circuit includes: The scanning logic unit is used to divide the time of one frame into two operation time periods; Odd-numbered row scanners, used to sequentially turn on odd-numbered row scan lines within one operating time period, and write odd-numbered row data signals into odd-numbered row pixels; The even-numbered row scanner is used to sequentially turn on the even-numbered row scanning lines to write the even-numbered row of data signals into the even-numbered row of pixels during another operating time period. 7. The drive circuit according to claim 6, wherein there are more than one odd row scanner and/or even row scanner, and the drive circuit further comprises: a counter, used to count the scanning operations performed by each of the odd row scanners during one operation period, and count the scanning operations performed by each of the even row scanners during another operation period The scan operations performed are counted. 8. The drive circuit according to claim 7, wherein the counter further comprises: The frequency multiplication module is used to set the count of the counter in one operation time period, so that each time the count corresponds to one of the odd row scanners to perform a scanning operation, and make all the odd row scanners perform scan operations during that operational time period; and In another said operation time period, the count of said counter is set, so that each said count corresponds to one said even-numbered row scanner performing a scan operation, and all said even-numbered row scanners are in this operation time period Execute the scan operation. 9. A liquid crystal display comprising the drive circuit according to any one of claims 6 to 8.

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