CN102024438A - Liquid crystal display source electrode driving device and driving method thereof - Google Patents

Abstract

The embodiment of the present invention discloses a liquid crystal display source driving device and a driving method, which relate to the field of liquid crystal displays, can select the best charging rate and optimize power consumption, effectively solve the problem of poor brightness, and avoid dark lines caused by it (Dim Line) phenomenon. A liquid crystal display source driving device, comprising: an output buffer unit and an auxiliary bias current unit, further comprising: an auxiliary bias that controls the auxiliary bias current unit to provide a dynamic auxiliary bias current to the output buffer unit current control unit. The invention is applied to liquid crystal displays.

Description

Liquid crystal display source driving device and driving method

technical field

The invention relates to the field of liquid crystal displays, in particular to a source driving device and a driving method of a liquid crystal display.

Background technique

During the working process of the liquid crystal display panel, due to the stray capacitance such as parasitic capacitance (Cgd) in the sub-pixel unit, the output buffer unit of the source driver must charge the liquid crystal capacitance and storage capacitance at the same time. Part of the stray capacitance is charged, so the inversion method of DOT Line has a large power consumption.

At present, the inversion method of 2 lines (2Line) or 1+2 lines (1+2Line) is usually used to save power consumption, but at the same time of saving power consumption, since the output buffer unit pair Two lines with the same polarity require different power, that is, the power required to charge the stray capacitance when charging the second line is less than the power required to charge the stray capacitance when charging the first line, there is a charging rate between two consecutive lines and The difference in the degree of charging saturation causes the inversion speed and angle of the two lines of liquid crystal with the same polarity to be inconsistent, resulting in a slight difference in the brightness of the two lines, and the phenomenon of dim line (Dim Line). With the emergence of 10bit and 12bit grayscale source drivers, the grayscale division is more detailed, and the accuracy of the analog voltage output by the source driver is higher, so this dim line phenomenon is more likely to appear.

The prior art provides a source driving device, as shown in FIG. 1 , an auxiliary bias current Iadd is provided by setting an auxiliary bias current unit 2, and the bias current Ibias output by the output buffer unit 1 jointly realizes the source driver. Pole drive to improve drive capability. However, the driving ability requirements between odd-numbered lines and even-numbered lines in multi-line dot inversion methods such as 2 lines or 1+2 lines are also inconsistent. Therefore, simply improving the driving capacity will cause unnecessary waste of power consumption. At the same time, the brightness difference problem cannot be solved, and the dim line phenomenon cannot be eliminated.

Contents of the invention

The technical problem to be solved by the present invention is to provide a liquid crystal display source driving device and driving method, which can select the best charging rate and optimize power consumption, effectively solve the problem of poor brightness, and avoid the dark line (Dim Line) phenomenon.

In order to solve the above-mentioned technical problems, the liquid crystal display source driver and the driving method of the present invention adopt the following technical solutions:

A liquid crystal display source driving device, comprising: an output buffer unit and an auxiliary bias current unit, further comprising: an auxiliary bias that controls the auxiliary bias current unit to provide a dynamic auxiliary bias current to the output buffer unit current control unit.

When the liquid crystal display is in two-line inversion or one plus two-line inversion mode, the auxiliary bias current control unit controls the auxiliary bias current unit to output The magnitude of the auxiliary bias current provided by the buffer unit is A, and the auxiliary bias current control unit controls the auxiliary bias current unit provided for the output buffer unit when the auxiliary bias current unit is in the second row where the two rows are reversed. Set the magnitude of the current as B, and A>B.

The auxiliary bias current control unit includes:

The auxiliary bias current control module is configured to control a dynamic auxiliary bias current whose output magnitude changes from the auxiliary bias current unit under the control of the auxiliary bias current control signal.

The auxiliary bias current control unit also includes:

A proportional control module, configured to control the amplitude of the output level of the auxiliary bias current control signal.

The auxiliary bias current control module includes: a first transistor and a second transistor controlled to be turned on by the auxiliary bias current control signal, and the first transistor and the second transistor are respectively connected to the auxiliary bias current unit The positive and negative power supply terminals of the auxiliary bias current unit are used to control the input of the positive and negative power supply terminals of the auxiliary bias current unit, so as to control the magnitude of the auxiliary bias current output by the auxiliary bias current unit.

The auxiliary bias current control signal is generated by the timing controller, which is the double frequency of the gate scanning signal CPV or the double frequency division of the polarity inversion signal POL.

A liquid crystal display source driving method, comprising:

At the moment when the two rows are reversed and the row is not turned on, a dynamic auxiliary bias current is selectively provided to the output buffer unit.

When the liquid crystal display is two-line inversion or one-plus-two-line inversion mode, then at the moment when the two-line inversion and different lines are turned on, the selection of providing a dynamic auxiliary bias current to the output buffer unit includes:

In the first row where the two rows are reversed, the magnitude of the auxiliary bias current provided for the output buffer unit is A;

In the second row where the two rows are reversed, the magnitude of the auxiliary bias current provided for the output buffer unit is B, where A>B.

In the technical solution of the present invention, by setting the auxiliary bias current control unit, the optimal charging rate and optimal power consumption of the first row and the second row can be selected according to the debugging results, and the rate of rising or falling of the data output voltage can be increased. At the same time, it meets the different requirements of different lines for power consumption, effectively solves the problem of poor brightness, and avoids the resulting dark line (Dim Line) phenomenon.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only of the present invention. For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

1 is a schematic structural diagram of a source driver device for a liquid crystal display in the prior art;

FIG. 2 is a first structural schematic diagram of a liquid crystal display source driving device according to an embodiment of the present invention;

3 is a schematic structural diagram of an auxiliary bias current control unit according to an embodiment of the present invention;

FIG. 4 is a second structural schematic diagram of a liquid crystal display source driving device according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of signal generation of a proportional control module according to an embodiment of the present invention;

FIG. 6 is a driving sequence effect diagram 1 of the embodiment of the present invention;

Fig. 7 is the driving sequence effect drawing 2 of the embodiment of the present invention;

8 is a flowchart of a method for driving a source of a liquid crystal display according to an embodiment of the present invention;

FIG. 9 is a flow chart of the method in step 101 in FIG. 8 of the present invention.

Explanation of reference signs:

1- output buffer unit; 2- auxiliary bias current unit;

3-auxiliary bias current control unit; 31-auxiliary bias current control module;

32-proportional control module; 311-first transistor; 312-second transistor.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiments of the present invention provide a liquid crystal display source driving device and a driving method, which can select an optimal charging rate and optimize power consumption, effectively solve the problem of poor brightness, and avoid the resulting dim line phenomenon.

Embodiment one

As shown in FIG. 2 , an embodiment of the present invention provides a liquid crystal display source driving device including: an output buffer unit 1 and an auxiliary bias current unit 2, and also includes: controlling the auxiliary bias current unit 2 to output buffer Unit 1 selects auxiliary bias current control unit 3 that provides a dynamic auxiliary bias current Iadd.

Wherein, the liquid crystal display is in 2-line or 2+1-line inversion mode, then in the second line of two-line inversion, the auxiliary bias current control unit 3 controls the auxiliary bias current unit 2 to When the first row of the two rows is reversed, the auxiliary bias current Iadd provided for the output buffer unit 1 is A, and the auxiliary bias current control unit 3 controls the auxiliary bias current unit 2 in the reversed state of the two rows. In the second row, the magnitude of the auxiliary bias current Iadd provided for the output buffer unit 1 is B, and A>B.

Further, as shown in FIG. 3 , the auxiliary bias current control unit 3 includes: an auxiliary bias current control module 31 and a proportional control module 32 .

Auxiliary bias current control module 31, used to control the dynamic auxiliary bias current of the auxiliary bias current unit output size change under the control of the auxiliary bias current control signal; proportional control module 32, used to control the The magnitude of the output level of the auxiliary bias current control signal.

As shown in FIG. 4 , the auxiliary bias current control module 31 includes: a first transistor 311 and a second transistor 312 controlled to be turned on by the auxiliary bias current control signal BCS, the first transistor 311 and the second transistor 312 They are respectively connected to the positive and negative power supply terminals (Vin- and Vin+) of the auxiliary bias current unit, and are used to control the input of the positive and negative power supply terminals (Vin- and Vin+ terminals) of the auxiliary bias current unit. Adding the BCS signal to the power supply terminals of Vin+ and Vin- can control whether the two transistors at Vin+ and Vin- are turned on or not and the degree of conduction through the high and low potentials of the BCS signal, thereby controlling the auxiliary bias current unit output. The size of the bias current.

Further, as shown in Figure 5, the realization of the proportional control module (Scale Selector) can be through the action of the level shifter (Level Shift), the level value of the BCS signal is raised or lowered to BCS1, further, by BCS1 controls the turn-on degree of the first transistor and the second transistor, thereby controlling the magnitude of the current supply at the power supply terminal of the auxiliary bias current unit, and realizing the proportional selection of Iadd.

Further, the implementation of the proportional control module (Scale Selector) can also use several digital selection signals DX1, DX2, DXn, and external resistors to pull up and pull down to control the percentage of Iadd current and power consumption.

The technical solution of the present invention is described below through a specific embodiment, as shown in Figure 6, wherein, CPV is the gate scan line signal; POL is the polarity inversion signal; BCS is the auxiliary bias current control signal, and BCS1 is the via The auxiliary bias current control signal output by the proportional control module after adjustment; Data is the data scanning line signal; Vcom is the common electrode line signal, where the BCS signal is generated by the timing controller, which is the double frequency of the CPV signal and the double frequency of the POL signal. crossover.

As shown in Figure 4 and Figure 6, specifically, the output buffer unit 1 (Source IC Buffer) drives the first line of the liquid crystal display 2Line reversed. At this time, since the liquid crystal capacitor is charged, the parasitic capacitance of the panel needs to be charged The power is relatively large, and a large driving capability is required. Therefore, it is necessary to turn on the transistor added to the power supply end of the auxiliary bias current unit 2 to start the auxiliary bias current unit 2 . Therefore, at this time, the BCS and BCS1 signals are at a high level, BCS1 controls the first transistor 311 and the second transistor 312 of the power supply of the auxiliary bias current unit 2 to turn on, and the auxiliary bias current unit 2 provides Iadd to the output buffer unit 1 , so that the speed at which the data voltage rises can be increased.

When the output buffer unit 1 drives the second line of the liquid crystal display 2Line reversed, at the same time when charging the liquid crystal capacitor, the parasitic capacitor charging power of the panel needs to be small, and the driving capacity is small, so it needs to be limited or not enabled Auxiliary bias current unit. At this time, the BCS and BCS1 signals are at low level, and the BCS1 signal controls the first transistor 311 and the second transistor 312 of the auxiliary bias current control module 31 to turn off, thereby turning off the power supply of the power supply terminal of the auxiliary bias current unit 2 , the auxiliary bias current unit 2 no longer provides Iadd to the output buffer unit 1, thereby delaying the rising speed of the data voltage.

In the technical solution of this embodiment, for the liquid crystal inversion mode of 2Line or 1+2Line, the liquid crystal charging rate of the first line can be faster than that of the unit without auxiliary bias current, while the charging rate of the liquid crystal of the second line is reduced Slow down, so as to achieve the purpose of saving unnecessary power consumption and balancing the brightness deviation of two rows of the same polarity.

In the embodiment shown in Figure 6, in conjunction with what is shown in Figure 4, the level amplitude of BCS1 is equal to the level amplitude of BCS, and the proportional control module 32 does not pull up or pull down the level of the BCS signal, but in Fig. In the embodiment shown in 7, the proportional control module 32 pulls up the level of the BCS signal to BCS1, and pulls it down to BCS2, so as to further control the conduction degree of the first transistor 311 and the second transistor 312, thereby realizing the second row On-demand adjustment of the charging rate.

It should be noted that the function of the BCS signal is to control the charging capability of the output buffer unit of the source driving device, which changes once per row. According to specific conditions, the size of Iadd output by the auxiliary bias current unit in the second row can be selected as 70%, 80% or 85% of the Iadd output by the auxiliary bias current unit in the first row. The specific value can be determined by the actual debugging results of the panel, and should not be limited, and it needs to be alternated instead of unchanged.

In the technical solution of the present invention, by setting the auxiliary bias current control unit, the optimal charging rate and optimal power consumption of the first row and the second row can be selected according to the debugging results, and the rate of rising or falling of the data output voltage can be increased. At the same time, it meets the different requirements of different lines for power consumption, effectively solves the problem of poor brightness, and avoids the resulting dark line (Dim Line) phenomenon.

The present invention also provides a source driving method using the above liquid crystal display source driving device, as shown in FIG. 8, the method includes:

Step 101 : Select and provide dynamic auxiliary bias current to the output buffer unit at the moment when two rows are reversed and different rows are turned on.

Further, the liquid crystal display is 2 lines or 2+1 line inversion mode, as shown in Figure 9, then step 101 includes:

Step 1011, in the first row where the two rows are reversed, the magnitude of the auxiliary bias current provided for the output buffer unit is A;

Step 1012, the magnitude of the auxiliary bias current provided for the output buffer unit is B, where A>B.

In the technical solution of the present invention, the optimal charging rate and optimal power consumption of the first row and the second row can be selected according to the debugging results, and while increasing the rate of rising or falling of the data output voltage, it satisfies the needs of different row pairs. The different requirements of power consumption effectively solve the problem of poor brightness and avoid the resulting dark line (Dim Line) phenomenon.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be realized by means of software plus necessary general-purpose hardware, and of course also by hardware, but in many cases the former is a better embodiment . Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a readable storage medium, such as a floppy disk of a computer , a hard disk or an optical disk, etc., including several instructions for enabling a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. A liquid crystal display source driver, comprising: an output buffer unit and an auxiliary bias current unit, further comprising: controlling the auxiliary bias current unit to provide a dynamic auxiliary bias to the output buffer unit Auxiliary bias current control unit for setting current. 2. The source driving device according to claim 1, wherein when the liquid crystal display is in two-line inversion mode or one plus two-line inversion mode, the auxiliary bias current control unit controls the auxiliary bias current control unit When setting the current unit in the first row where the two rows are reversed, the size of the auxiliary bias current provided for the output buffer unit is A, and the auxiliary bias current control unit controls the auxiliary bias current unit in the two rows When the second row is reversed, the magnitude of the auxiliary bias current provided for the output buffer unit is B, and A>B. 3. The source driver device according to claim 2, wherein the auxiliary bias current control unit comprises: The auxiliary bias current control module is configured to control a dynamic auxiliary bias current whose output magnitude changes from the auxiliary bias current unit under the control of the auxiliary bias current control signal. 4. The source driver device according to claim 3, wherein the auxiliary bias current control unit further comprises: A proportional control module, configured to control the amplitude of the output level of the auxiliary bias current control signal. 5. The source driver device according to claim 3 or 4, wherein the auxiliary bias current control module comprises: a first transistor and a second transistor that are turned on by the auxiliary bias current control signal , the first transistor and the second transistor are respectively connected to the positive and negative power supply terminals of the auxiliary bias current unit, and are used to control the input of the positive and negative power supply terminals of the auxiliary bias current unit, thereby controlling the auxiliary The magnitude of the auxiliary bias current output by the bias current unit. 6. The source driving device according to claim 5, wherein the auxiliary bias current control signal is generated by a timing controller and is the double frequency of the gate scan signal CPV or the polarity inversion signal POL 2-way frequency. 7. A liquid crystal display source driving method, characterized in that, comprising: At the moment when two rows are reversed and different rows are turned on, a dynamic auxiliary bias current is provided to the selection of the output buffer unit. 8. The source driving method according to claim 7, wherein when the liquid crystal display adopts two-line inversion or one-plus-two-line inversion mode, at the moment when two lines are inverted and different lines are turned on, the The output buffer unit options to provide dynamic auxiliary bias current include: In the first row where the two rows are reversed, the magnitude of the auxiliary bias current provided for the output buffer unit is A; In the second row where the two rows are reversed, the magnitude of the auxiliary bias current provided for the output buffer unit is B, where A>B.

Images