TWI701655B - Common voltage compensation apparatus and common voltage compensation method applied to display driving circuit - Google Patents

Abstract

A common voltage compensation apparatus applied to a display driving circuit is disclosed. The display driving circuit includes a receiving unit and a latching unit. The receiving unit receives a plurality of input data and transmits them to the latching unit. The common voltage compensation apparatus includes a judging unit and a compensating unit. The judging unit is coupled between the receiving unit and the latching unit and used to judge whether a coupling common voltage should be compensated according to the plurality of input data. The compensating unit is coupled to the judging unit and used to selectively compensate the coupling common voltage according to a judging result of the judging unit to generate a compensated common voltage.

Description

Common voltage compensation device and common voltage compensation method applied to display driving circuit

The present invention relates to displays, and in particular relates to a common voltage compensation device and a common voltage compensation method applied to a display driving circuit.

Please refer to Figure 1 to Figure 5. FIG. 1 is a schematic diagram showing a traditional LCD panel architecture. Figures 2 to 3 illustrate that the coupling of the common voltage (VCOM) is directly affected by the output voltage of the source driver. 4A to 4C respectively illustrate an embodiment of an ideal display pattern displayed on the display panel, a display pattern showing horizontal crosstalk (Crosstalk), and different data line positions. FIG. 5 shows a timing diagram in which the common voltage is distorted by different data lines and cannot be restored to the ideal voltage value before the gate is turned off (as shown in the circles A3 and A4).

Generally speaking, in order to reduce the common voltage coupling phenomenon on the side of the liquid crystal display panel, the circuit designer can add a logic operation mechanism to the common voltage buffer circuit of the display driving circuit. However, due to the limited area of the display driving circuit, once more logic control circuits and common voltage buffer control circuits are added to the display driving circuit, the area of the display driving circuit will inevitably be wasted.

In addition, panel designers can reduce the noise of the common voltage by reducing the pixel capacitance of the liquid crystal display array, or by enhancing the driving capability of the common voltage to resist the coupling of display data. However, as the size of the display panel becomes larger and larger, the complexity of the display panel design also increases. As a result, the traditional methods of reducing the pixel capacitance and enhancing the driving capability of the common voltage will be greatly restricted. get over.

In view of this, the present invention proposes a common voltage compensation device and a common voltage compensation method applied to a display driving circuit to effectively solve the above-mentioned problems encountered in the prior art.

A specific embodiment according to the present invention is a common voltage compensation device. In this embodiment, the common voltage compensation device is applied to the display driving circuit. The display driving circuit includes a receiving unit and a latch unit. The receiving unit receives a plurality of input data and transmits the plurality of input data to the latch unit. The common voltage compensation device includes a judgment unit and a compensation unit. The judging unit is coupled between the receiving unit and the latch unit for judging whether to compensate the coupled common voltage according to the plurality of input data. The compensation unit is coupled to the judgment unit, and is used for selectively compensating the coupled common voltage according to the judgment result of the judgment unit to generate a compensated common voltage.

In one embodiment, if the judgment result of the judgment unit is yes, the compensation unit compensates the coupled common voltage to generate the compensated common voltage; if the judgment result of the judgment unit is no, the compensation unit will not compensate the coupled common voltage Make compensation.

In an embodiment, the common voltage compensation device further includes a buffer unit. The buffer unit has a first input terminal, a second input terminal and an output terminal. The first input terminal is coupled to the compensation unit and the second input terminal is coupled to the output terminal, and the output terminal outputs the compensated common voltage.

In one embodiment, the display driving circuit further includes an output pad. The output pad is coupled between the display panel and the output terminal of the buffer unit for outputting the compensated common voltage to the display panel.

In an embodiment, when the compensation unit compensates for the coupled common voltage, the compensation unit generates a pre-charging/pre-discharging voltage (Pre-charging/pre-discharging voltage) and pre-charging/pre-discharging voltage according to the plurality of input data. The discharge voltage is superimposed with the coupled common voltage to generate the compensated common voltage.

In one embodiment, the precharge/predischarge voltage and the coupled common voltage are inverse to each other, and the precharge/predischarge voltage is ahead of the coupled common voltage in time.

In one embodiment, the display drive circuit is a source drive integrated circuit.

Another specific embodiment according to the present invention is a common voltage compensation method. In this embodiment, the common voltage compensation method is applied to the display driving circuit. The common voltage compensation method includes the following steps:

(a) The display driving circuit receives a plurality of input data;

(b) Judging whether it is necessary to compensate the coupled common voltage based on the plurality of input data; and

(c) According to the judgment result of step (b), selectively compensate the coupled common voltage to generate a compensated common voltage.

Compared with the prior art, the common voltage compensation device and the common voltage compensation method of the present invention are based on the display drive circuit (source drive integrated circuit) according to the multiple input data it receives to determine whether to generate and couple the common voltage The pre-charge/pre-discharge voltage signal leading in time is used to compensate the coupled common voltage to reduce the noise of the coupled common voltage. Therefore, the panel designer does not need to reduce the noise of the common voltage by reducing the pixel capacitance value of the liquid crystal display array, nor does it need to enhance the driving capability of the common voltage to resist the coupling of display data, so it can greatly reduce The complexity of the display panel design.

In addition, the common voltage compensation device and common voltage compensation method of the present invention can compensate the coupled common voltage according to different display data of the display panel, different bias settings and different device size control (Device size control) to make corresponding adjustments, so the flexibility of common voltage compensation can be greatly increased.

The advantages and spirit of the present invention can be further understood from the following detailed description of the invention and the accompanying drawings.

A specific embodiment according to the present invention is a common voltage compensation device. In this embodiment, the common voltage compensation device is applied to a display drive circuit, such as a source drive integrated circuit, but it is not limited to this.

Please refer to FIG. 6. FIG. 6 is a schematic diagram showing the common voltage compensation device in this embodiment applied to the display driving circuit.

As shown in FIG. 6, the display driving circuit SD is coupled to the display panel PL. The display driving circuit SD includes a receiving unit RX, a latch unit LA, a level shift unit LS, a digital analog conversion unit DAC, and N buffer units BF1~BFN corresponding to N channels CH1~CHN, where N is a positive integer .

The receiving unit RX is coupled to the latch unit LA. The latch unit LA is coupled to the level shift unit LS. The level shift unit LS is coupled to the digital-to-analog conversion unit DAC. The digital-to-analog conversion unit DAC is coupled to the positive input terminals + of the N buffer units BF1~BFN. The negative input terminals-and output terminals of the N buffer units BF1 ~ BFN are coupled to each other.

When the receiving unit RX receives N input data DAT1~DATN corresponding to the N channels CH1~CHN, the receiving unit RX transmits the N input data DAT1~DATN to the latch unit LA. Then, the level shift unit LS performs level shift processing on the N input data DAT1~DATN, and then the digital analog conversion unit DAC converts the digital signal into analog signal processing, and then the N buffer units BF1~BFN are respectively output to the display panel PL through the N channels CH1~CHN.

In this embodiment, the common voltage compensation device 6 includes a judgment unit 60, a compensation unit 62, and a buffer unit 64. The buffer unit 64 has a positive input terminal +, a negative input terminal − and an output terminal K. The judging unit 60 is coupled between the receiving unit RX and the latch unit LA. The judgment unit 60 is also coupled to the compensation unit 62. The compensation unit 62 is coupled to the positive input terminal + of the buffer unit 64. The negative input terminal-and the output terminal K of the buffer unit 64 are coupled to each other. The output terminal K of the buffer unit 64 is coupled to the display panel PL through the output pad PAD.

The judging unit 60 is used for judging whether the coupled common voltage VCOM needs to be compensated according to the N input data DAT1 ~ DATN and providing the judgment result JR to the compensation unit 62. The compensation unit 62 is used to selectively compensate the coupled common voltage VCOM according to the judgment result JR of the judgment unit 60 to generate the compensated common voltage VCOM' to the positive input terminal + of the buffer unit 64, and then the buffer unit 64 The output terminal K outputs the compensated common voltage VCOM' to the display panel PL through the output pad PAD.

In detail, if the judgment result JR of the judgment unit 60 is yes, that is, the coupled common voltage VCOM needs to be voltage compensated, the compensation unit 62 performs voltage compensation on the coupled common voltage VCOM to generate the compensated common voltage VCOM' If the judgment result JR of the judgment unit 60 is no, that is, the coupled common voltage VCOM does not need to be voltage compensated, step S14 will not perform voltage compensation on the coupled common voltage VCOM.

In practical applications, when the compensation unit 62 performs voltage compensation on the coupled common voltage VCOM, the compensation unit 62 generates the pre-charge/pre-discharge voltage PC (as shown in FIG. 7) according to the plurality of input data DAT1 ~ DATN, and The pre-charge/pre-discharge voltage PC and the coupled common voltage VCOM are superimposed to generate the compensated common voltage VCOM'.

In addition, the precharge/predischarge voltage PC and the coupled common voltage VCOM are inverse to each other, and the precharge/predischarge voltage PC is ahead of the coupled common voltage VCOM in time. In this way, when the precharge/predischarge voltage PC is superimposed on the coupled common voltage VCOM, most of the original noise of the coupled common voltage VCOM will be offset by the precharge/predischarge voltage PC which is inverted, so that compensation The noise of the rear common voltage VCOM' is greatly reduced, so it can effectively prevent the horizontal crosstalk (Crosstalk) phenomenon of the picture displayed on the display panel.

For example, as shown in FIG. 7, when the compensation unit 62 performs voltage compensation on the coupled common voltage VCOM, the compensation unit 62 generates the pre-charge/pre-discharge voltage PC according to the plurality of input data DAT1 ~ DATN, and then The charge/pre-discharge voltage PC is superimposed with the coupled common voltage VCOM to generate the compensated common voltage VCOM'.

Next, the time t1~t4 will be taken as an example for description.

At time t1, the output voltages VOUT (SD1) and VOUT (SD2) of the display driving circuit are at a low level, and the conversion signal STB changes from a low level to a high level. At this time, the voltage level of the pre-discharge voltage PC generated by the compensation unit 62 begins to decrease, and the coupled common voltage VCOM remains unchanged. Therefore, during the period from time t1 to t2, the voltage level of the compensated common voltage VCOM' generated by superimposing the precharge/predischarge voltage PC and the coupled common voltage VCOM will decrease from the ideal voltage value VID, and Time t2 reaches a low point.

At time t2, the conversion signal STB changes from a high level to a low level, indicating that the output voltages VOUT (SD1) and VOUT (SD2) of the driving circuit change from a low level to a high level. At this time, the voltage level of the pre-discharge voltage PC generated by the compensation unit 62 starts to rise from the lowest point, and the coupled common voltage VCOM starts to rise first and then drop noise. During the display period DR from time t2 to t3, since most of the noise of the coupled common voltage VCOM can be offset by the inverted pre-discharge voltage PC, the pre-charge/pre-discharge voltage PC and the coupled common The voltage level of the compensated common voltage VCOM' generated after the voltage VCOM is superimposed will rise from a low point to the ideal voltage value VID and then remain at the ideal voltage value VID, so it can effectively avoid horizontal crosstalk during the display period DR (Crosstalk) The phenomenon.

At time t3, the output voltages VOUT (SD1) and VOUT (SD2) of the display driving circuit are at a high level, and the conversion signal STB changes from a low level to a high level. At this time, the voltage level of the pre-discharge voltage PC generated by the compensation unit 62 starts to rise, and the coupled common voltage VCOM remains unchanged. Therefore, during the period from time t3 to t4, the voltage level of the compensated common voltage VCOM' generated by superimposing the precharge/predischarge voltage PC and the coupled common voltage VCOM will increase from the ideal voltage value VID, and A high point is reached at time t4.

As for the other situations, analogy can be made according to the above-mentioned embodiment, so it will not be repeated here.

Another specific embodiment according to the present invention is a common voltage compensation method. In this embodiment, the common voltage compensation method is applied to a display drive circuit, such as a source drive integrated circuit, but it is not limited to this.

Please refer to FIG. 8. FIG. 8 shows a flowchart of the common voltage compensation method in this embodiment. As shown in Figure 8, the common voltage compensation method may include the following steps:

Step S10: the display driving circuit receives a plurality of input data;

Step S12: Determine whether the coupled common voltage needs to be compensated according to the plurality of input data; and

Step S14: selectively compensate the coupled common voltage according to the judgment result of step S12 to generate the compensated common voltage, and output it to the display panel.

In detail, if the judgment result of step S12 is yes, step S14 will compensate the coupled common voltage to generate a compensated common voltage; if the judgment result of step S12 is no, then step S14 will not affect the coupling The common voltage is compensated.

It should be noted that when step S14 compensates for the coupled common voltage, step S14 generates a precharge/predischarge voltage according to the plurality of input data and superimposes the precharge/predischarge voltage with the coupled common voltage to generate Common voltage after compensation.

In practical applications, the pre-charge/pre-discharge voltage and the coupled common voltage are inverse to each other, and the pre-charge/pre-discharge voltage is ahead of the coupled common voltage in time. Therefore, when the pre-charge/pre-discharge voltage is superimposed on the coupled common voltage, most of the original noise of the coupled common voltage will be offset by the inverse pre-charge/pre-discharge voltage, so that the compensated common voltage is The noise is greatly reduced, so it can effectively avoid the phenomenon of horizontal crosstalk (Crosstalk) in the picture displayed on the display panel.

Compared with the prior art, the common voltage compensation device and the common voltage compensation method of the present invention are based on the display drive circuit (source drive integrated circuit) according to the multiple input data it receives to determine whether to generate and couple the common voltage The pre-charge/pre-discharge voltage signal leading in time is used to compensate the coupled common voltage to reduce the noise of the coupled common voltage. Therefore, the panel designer does not need to reduce the noise of the common voltage by reducing the pixel capacitance value of the liquid crystal display array, nor does it need to enhance the driving capability of the common voltage to resist the coupling of display data, so it can greatly reduce The complexity of the display panel design.

In addition, the common voltage compensation device and common voltage compensation method of the present invention can compensate the coupled common voltage according to different display data of the display panel, different bias settings and different device size control (Device size control) to make corresponding adjustments, so the flexibility of common voltage compensation can be greatly increased.

Through the detailed description of the preferred embodiments above, it is hoped that the characteristics and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, its purpose is to cover various changes and equivalent arrangements within the scope of the patent application for the present invention.

S10~S14: steps

1: display device

PL: display panel

PCB: circuit board

TCON: Timing Controller

PW: Power

VCOM: coupled common voltage

SD, SD1~SDN: source drive integrated circuit

GD, GD1~GDN: Gate drive integrated circuit

DAT: display data

BF1~BF2: buffer unit

SW1~SW2: switch unit

CH1~CH2: Channel

CON: control unit

VOUT(SD1)~VOUT(SD2): The output voltage of the source drive integrated circuit

t1~t4: time

GPX: Gray pixels

BPX: black pixel

HCT: horizontal crosstalk

DLA~DLB: display line

GX~GY: gate line

PXB1~PXB2: pixels

RX: receiving unit

LA: Latch unit

LS: Level shift unit

DAC: digital analog conversion unit

BF1~BFN: buffer unit

CH1~CHN: Channel

C: Capacitance

R: resistance

6: Public voltage compensation device

60: Judgment unit

62: compensation unit

64: buffer unit

DAT1~DATN: input data

JR: Judgment result

VCOM’: Common voltage after compensation

PAD: output pad

A1~A4: circle around

1FM: One frame

STB: Conversion signal

PC: precharge/predischarge voltage

DR: Display period

VIC: ideal voltage value

The drawings of the present invention are described as follows: FIG. 1 is a schematic diagram showing the structure of a traditional liquid crystal display panel. Figures 2 to 3 show that the coupling of the common voltage is directly affected by the output voltage of the source driver. 4A to 4C respectively show an embodiment of an ideal display pattern displayed on the display panel, a display pattern with horizontal crosstalk, and different data line positions. FIG. 5 is a timing diagram in which the common voltage is distorted by different data lines and cannot be restored to the ideal voltage value before the gate is turned off. FIG. 6 is a schematic diagram illustrating the application of the common voltage compensation device in a display driving circuit according to a preferred embodiment of the present invention. FIG. 7 is a timing diagram of the common voltage compensation device of the present invention superimposing the precharge/predischarge voltage and the coupled common voltage to generate the compensated common voltage. FIG. 8 is a flowchart of a common voltage compensation method in another preferred embodiment of the present invention.

S10~S14: steps

Claims (9)

A common voltage compensation device is applied to a display drive circuit. The display drive circuit includes a receiving unit and a latch unit. The receiving unit receives a plurality of input data and transmits the plurality of input data to the latch unit. The common voltage compensation device includes: a judgment unit, coupled between the receiving unit and the latch unit, for judging whether a coupled common voltage needs to be compensated according to the plurality of input data; and a compensation unit, which is coupled Connected to the judging unit for selectively compensating the coupled common voltage according to the judging result of the judging unit to generate a compensated common voltage; wherein, when the compensation unit compensates the coupled common voltage The compensation unit generates a pre-charging/pre-discharging voltage (Pre-charging/pre-discharging voltage) according to the plurality of input data and superimposes the pre-charging/pre-discharging voltage with the coupled common voltage to generate the compensation After the common voltage, the pre-charge/pre-discharge voltage and the coupled common voltage are inverse to each other, and the pre-charge/pre-discharge voltage is ahead of the coupled common voltage in time. For example, the public voltage compensation device described in item 1 of the scope of patent application, wherein if the judgment result of the judgment unit is yes, the compensation unit compensates the coupled common voltage to generate the compensated common voltage; if the judgment unit If the judgment result is no, the compensation unit will not compensate the coupled common voltage. The common voltage compensation device described in the first item of the scope of patent application further includes: a buffer unit having a first input terminal, a second input terminal and an output terminal, the first input terminal is coupled to the compensation unit and The second input terminal is coupled to the output terminal, and the output terminal outputs the compensated common voltage. According to the public voltage compensation device described in claim 3, the display drive circuit further includes an output pad coupled to a display panel and the output terminal of the buffer unit Between, used to output the compensated common voltage to the display panel. In the common voltage compensation device described in item 1 of the scope of patent application, the display driving circuit is a source driving integrated circuit. A common voltage compensation method is applied to a display drive circuit. The common voltage compensation method includes the following steps: (a) The display drive circuit receives a plurality of input data; (b) According to the plurality of input data, it is determined whether a coupling is required And (c) selectively compensate the coupled common voltage according to the judgment result of step (b) to generate a compensated common voltage; wherein, when step (c) the coupled common voltage When the voltage is compensated, step (c) is to generate a precharge/predischarge voltage according to the plurality of input data and superimpose the precharge/predischarge voltage with the coupled common voltage to generate the compensated common voltage, the The pre-charge/pre-discharge voltage and the coupled common voltage are inverse to each other, and the pre-charge/pre-discharge voltage is ahead of the coupled common voltage in time. For example, the common voltage compensation method described in item 6 of the scope of patent application, wherein if the judgment result of step (b) is yes, then step (c) compensates the coupled common voltage to generate the compensated common voltage; if If the judgment result of step (b) is no, then step (c) will not compensate the coupled common voltage. For the common voltage compensation method described in item 6 of the scope of patent application, wherein the display driving circuit is coupled to a display panel, the common voltage compensation method further includes the following steps: (d) outputting the compensated common voltage to the display panel. In the common voltage compensation method described in item 6 of the scope of patent application, the display drive circuit is a source drive integrated circuit.

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