TWI469128B - Voltage calibration circuit and related liquid crystal display device - Google Patents

Description

Voltage calibration circuit and liquid crystal display device thereof

The invention relates to a voltage calibration circuit and related liquid crystal display device, in particular to a voltage calibration circuit capable of actively detecting a coupling voltage and related liquid crystal display device.

Liquid Crystal Display Device (LCD Device) has the advantages of slimness, power saving and low radiation, so it has been widely used in computer screens, mobile phones, personal digital assistants (PDAs), flat screen TVs, and others. On electronic products such as communication/entertainment equipment. The working principle of the liquid crystal display device is to change the arrangement state of the liquid crystal molecules in the liquid crystal layer by changing the voltage difference between the two ends of the liquid crystal layer, thereby changing the light transmittance of the liquid crystal layer, and then matching the light source provided by the backlight module to display an image.

Thin Film Transistor (TFT) liquid crystal display devices are currently the most popular display devices, and the functions and architectures of display modules or driver chips have gradually matured. Please refer to FIG. 1A. FIG. 1A is a schematic diagram of a thin film transistor liquid crystal display device 10 in the prior art. The thin film transistor liquid crystal display device 10 includes a display module 120, a source driver 160 and a gate driver 180. The display module 120 is provided with parallel data lines D1 to Dm, parallel gate lines G1 to Gn, and display units P11 to Pmn. The data lines D1 to Dm and the gate lines G1 to Gn are alternately arranged with each other, and the display units P11 to Pmn are respectively disposed at the intersections of the corresponding data lines and the gate lines. The source driver 160 and the gate driver 180 generate a driving signal and a gate signal, respectively. Each display unit on the display module 120 includes a thin film transistor switch 100 and a liquid crystal capacitor 140, each One end of a liquid crystal capacitor is coupled to a corresponding data line through a corresponding thin film transistor switch, and the other end is coupled to a common voltage Vcom. When the gate transistor signal generated by the gate driver 180 is received to turn on the thin film transistor switch of the display unit, the liquid crystal capacitor of the display unit is electrically connected to the corresponding data line to receive the slave source driver 160. The driving signal is transmitted, so the display unit can control the rotation degree of the liquid crystal molecules according to the electric charge of the liquid crystal capacitor memory to display images of different gray levels.

There is a parasitic capacitance 111 in each display unit. When the gate lines G1~Gn are open or At the moment of shutdown, the voltage change affects the voltage of the display cells P11 to Pmn via the parasitic capacitance 111. When the gate lines G1 to Gn are turned on, the voltages of the display units P11 to Pmn are charged to the correct voltage. When the gate lines G1 G Gn are turned off, the parasitic capacitance 111 generates a downward coupling voltage on the display units P11 P Pmn. Since the source driver 160 is no longer charged, the positive and negative voltages of the display units P11 to Pmn are symmetrical to each other. Vcom, where Vcom is a fixed voltage output. In this way, the positive and negative liquid crystals of the same display material are rotated to the same extent to display the same gray scale. However, due to the drift of the LCD panel process, a slight difference in the parasitic capacitance 111 of different LCD panels may occur, which causes some of the LCD panels with different differences to be turned off after the gate lines G1 to Gm are turned off, and the parasitic capacitances 111 are turned down to the display units P11 to Pmm. The positive and negative voltages after coupling will be asymmetrical to Vcom, causing the difference in gray scale to cause the LCD panel to flicker.

Please refer to FIG. 1B, which is a waveform diagram of each display unit in FIG. 1A. In Figure 1B, when the gate line (eg, G1) is raised from a negative potential VGL (eg, -12V) to a positive potential VGH (eg, 15V), it indicates that the gate line is turned on, where GND is grounded. Bit. The source driver 160 charges a display voltage to the storage capacitor 140. When the gate line is turned off, the gate voltage is reduced from a positive potential VGH (eg, 15V) to a negative potential VGL (eg, -12V). At this time, due to the existence of the parasitic capacitance 111, the storage capacitor 140 is coupled to a voltage value (generally about 1V), and the coupled same data voltage value is symmetric to an LCD panel common voltage Vcom. When different LCD panels When the parasitic capacitance 111 is too large, the coupled display units P11~Pmm will be asymmetrical to Vcom and cause flicker.

In order to solve this flicker phenomenon, the prior art has a set of non-volatile memory (NVM), which adjusts the common voltage according to the degree of flicker of each liquid crystal display device module. However, this action makes the module manufacturing process a more burning process.

Therefore, the main object of the present invention is to provide a liquid crystal display device capable of actively detecting a coupling voltage without a burning process.

The invention discloses a voltage calibration circuit. The voltage calibration circuit includes a coupled voltage detection circuit and a common voltage circuit. The coupled voltage detecting circuit is configured to detect a coupling voltage during an initial period and generate a compensation voltage according to the coupling voltage. The common voltage circuit is configured to adjust a common voltage according to the compensation voltage and output the common voltage to a display module during a display period.

The invention further discloses a liquid crystal display device. The liquid crystal display device comprises a display module, a gate driving circuit, a source driving circuit and a voltage calibration circuit. The display module includes a plurality of stray capacitances. The gate drive circuit is configured to generate a plurality of gate signals. The source driving circuit is coupled to the display module for outputting a display voltage to the display module. The voltage calibration circuit includes a coupled voltage detection circuit and a common voltage circuit. The coupled voltage detecting circuit is configured to detect a coupling voltage during an initial period and generate a compensation voltage according to the coupling voltage. The common voltage circuit is configured to adjust a common voltage according to the compensation voltage and output the common voltage to a display module during a display period.

The invention further discloses a voltage calibration circuit. The voltage calibration circuit includes a coupling A voltage detecting circuit and a source driving circuit. The coupled voltage detecting circuit is configured to detect a coupling voltage during an initial period and generate a compensation voltage according to the coupling voltage. The source driving circuit is configured to output a display voltage to a display module according to the compensation voltage during a display period.

The invention further discloses a liquid crystal display device. The liquid crystal display device includes a display A module, a gate drive circuit, and a voltage calibration circuit. The display module includes a plurality of stray capacitances. The gate drive circuit is configured to generate a plurality of gate signals. The voltage calibration circuit includes a coupled voltage detecting circuit and a source driving circuit. The coupled voltage detecting circuit is configured to detect a coupling voltage during an initial period and generate a compensation voltage according to the coupling voltage. The source driving circuit is configured to output a display voltage to a display module according to the compensation voltage during a display period.

10‧‧‧Thin-film transistor liquid crystal display device

120, 200, 300, 400, 500‧‧‧ display modules

160‧‧‧Source Driver

180‧‧‧gate driver

D1~Dm‧‧‧ data line

G1~Gn‧‧‧ gate line

P11~Pmn‧‧‧ display unit

140‧‧‧Liquid Crystal Capacitor

100‧‧‧Thin-film transistor switch

Vcom‧‧‧Common voltage

250, 350, 450, 550, 650 ‧ ‧ voltage calibration circuit

750, 850, 950‧‧‧ voltage calibration circuit

20, 30, 40, 50‧‧‧ liquid crystal display devices

220, 320, 420, 520‧‧‧ source drive circuit

240, 340, 440, 540‧‧ ‧ gate drive circuit

260, 360, 460, 560‧‧‧coupled voltage detection circuit

280, 380, 480, 580‧ ‧ common voltage circuit

290, 390, 490, 590, 591‧ ‧ switch

262‧‧‧ Analog Digital Converter

264‧‧‧ lookup table

266‧‧‧Digital Analog Converter

V _FD , V _{FD_source ‧‧‧coupled} voltage

T _VCOM ‧‧‧Common voltage endpoint

V _{SHFT ‧‧‧compensation} voltage

310, 510‧‧‧ voltage setting unit

Vcs, Vcs’‧‧‧ display voltage

FIG. 1A is a schematic view of a conventional liquid crystal display device.

Figure 1B is a waveform diagram of each of the display units in Figure 1A.

2A is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

2B is a waveform diagram of a display unit according to an embodiment of the present invention.

2C is an exemplary embodiment of a coupled voltage detection circuit 260 of the present invention.

3 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

4 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 5 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

6A is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 6B is a waveform diagram of a display unit according to an embodiment of the present invention.

Figure 7 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

Figure 8 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

Figure 9 is a schematic view of a liquid crystal display device according to an embodiment of the present invention.

Please refer to FIG. 2A. FIG. 2A is a schematic diagram of a liquid crystal display device 20 according to an embodiment of the present invention. The liquid crystal display device 20 includes a display module 200, a source driving circuit 220, a gate driving circuit 240, and a voltage calibration circuit 250. The voltage calibration circuit 250 includes a coupled voltage detection circuit 260, a common voltage circuit 280, and a switch 290. The structure of the liquid crystal display device 20 is similar to that of the thin film transistor liquid crystal display device 10 of FIG. 1, and therefore the same portions will not be described again. The gate driving circuit 240 is configured to generate a plurality of gate signals to sequentially turn on/off the plurality of gate lines. The source driving circuit 220 is configured to input a plurality of display voltages to the plurality of storage capacitors of the display module 200 when the gate line is turned on (ie, from a negative potential to a positive potential). When the display module 200 is at the falling edge of the plurality of gate signals (ie, the plurality of gate lines are closed), the parasitic capacitance of the display module 200 (111 of FIG. 1A) generates a coupling voltage V _FD , and the pull-down display mode One of the groups 200 has a common voltage terminal T _VCOM which is a common voltage Vcom. The coupling voltage detecting circuit 260 is coupled to the common voltage terminal T _{VCOM of the} display module 200 through the switch 290 for detecting the coupling voltage V _FD and generating the coupling voltage V _FD according to the initial period of the liquid crystal display device 20 . A compensation voltage V _SHFT . The initial period of the liquid crystal display device 20 is one of the periods before the liquid crystal display device 20 is turned on. The common voltage circuit 280 is coupled to the common voltage terminal T _{VCOM of the} display module 200 through the switch 290 for adjusting the common voltage Vcom and the output common voltage Vcom according to the compensation voltage V _SHFT for a display period of the liquid crystal display device 20 Module 200. The display period of the liquid crystal display device 20 is one period during which the liquid crystal display device 20 displays a screen. The switch 290 is coupled to the display module 200, the coupled voltage detecting circuit 260, and the common voltage circuit 280 for controlling the display module 200 to be coupled to the common voltage circuit 280 or the coupled voltage detecting circuit 260. Therefore, the liquid crystal display device 20 of the embodiment of the present invention can detect the coupling voltage V _FD generated by the parasitic capacitance in the initial period of the liquid crystal display device 20 and actively adjust the common voltage Vcom to avoid flicker, without burning. Record the action to reduce the process time and increase the unit capacity.

Please refer to FIG. 2B at the same time. FIG. 2B is a waveform diagram of a display unit according to an embodiment of the present invention. In detail, in the initial period, the common voltage Vcom is first preset to an initial voltage value (for example, 0V). When the gate driving circuit 240 turns off the gate line (ie, from the positive potential VGH to the negative potential VGL), the switch 290 controls the common voltage terminal T _{VCOM of the} display module 200 to be coupled to the coupled voltage detecting circuit 260. The coupled voltage detecting circuit 260 detects the coupled voltage V _FD and generates a compensation voltage V _SHFT according to the coupling voltage V _FD . Preferably, the coupling voltage V _FD can be stored in a register of the coupled voltage detecting circuit 260 (not shown in FIG. 2). During the display period, the switch 290 controls the common voltage terminal T _{VCOM of the} display module 200 to be coupled to the common voltage circuit 280. The common voltage circuit 280 adjusts the common voltage Vcom according to the compensation voltage V _SHFT and outputs the common voltage Vcom to the display module 200. . For example, the common voltage Vcom is initially 0V. When the gate line is turned off, the coupling voltage detecting circuit 260 detects the coupling voltage V _FD = -0.6 V, and generates a compensation voltage V _SHFT = -1.2 V according to the coupling voltage V _FD . During the display period, the common voltage circuit 280 _adjusts the common voltage Vcom from 0V to -1.2V according to the compensation voltage V SHFT , and outputs a common voltage Vcom of -1.2V to the display module 200.

Please refer to FIG. 2C at the same time, and FIG. 2C is an exemplary embodiment of the coupled voltage detecting circuit 260 of the present invention. Not limited to this. The coupled voltage detection circuit 260 includes an analog to digital converter 262, a lookup table 264, and a digital analog converter 266. The analog to digital converter 262 is operative to receive the analog coupling voltage V _FD and convert the coupling voltage V _FD to a digital value D _FD . The lookup table 264 outputs a digital value D _SHFT corresponding to the compensation voltage V _SHFT according to the digital value D _FD . The digital analog converter 266 is _{operative to} convert to the analog offset voltage V _SHFT based on the digital value D _SHFT of the compensation voltage.

In an embodiment of the invention, the voltage calibration circuit may further comprise a voltage setting unit. Please refer to FIG. 3, which is a schematic diagram of a liquid crystal display device 30 according to another embodiment of the present invention. In FIG. 3, the liquid crystal display device 30 includes a display module 300, a source driving circuit 320, a gate driving circuit 340, and a voltage calibration circuit 350. The voltage calibration circuit 350 includes a coupled voltage detection circuit 360, a common voltage circuit 380, a switch 390, and a voltage setting unit 310. The difference between the embodiment and the embodiment shown in FIG. 2A is that the voltage setting unit 310 is coupled to the coupling voltage detecting circuit 360 and the common voltage circuit 380 for setting a preset offset value of the common voltage Vcom. When the gate driving circuit 240 turns off the gate line, the switch 390 controls the common voltage terminal T _{VCOM of the} display module 300 to be coupled to the coupled voltage detecting circuit 360. The coupled voltage detecting circuit 360 detects the coupled voltage V _FD and generates a compensation voltage V _SHFT through a relationship with the coupled voltage V _FD or a look-up table. During the display period, the switch 390 controls the common voltage terminal T _{VCOM of the} display module 300 to be coupled to the common voltage circuit 380. The common voltage circuit 380 compares the preset value of the common voltage Vcom and the compensation voltage V _{SHFT to} adjust and multiply. The common voltage Vcom is output to the display module 300. For example, the common voltage Vcom is initially 0V. When the gate line is turned off, the coupling voltage detecting circuit 360 detects the coupling voltage V _FD = -0.6V, and the voltage setting unit 310 sets the offset of the common voltage Vcom to a preset value of -1V. Therefore, the coupled voltage detecting circuit 360 generates the compensation voltage V _SHFT = _-0.2 V in accordance with the coupling voltage V _FD . During the display period, the common voltage circuit 380 compares the offset compensation voltage V _SHFT and the offset preset value of the common voltage Vcom (ie, -0.2V+-1V), and adjusts the common voltage Vcom from 0V to -1.2V, and A common voltage Vcom of -1.2V is output to the display module 300.

In other embodiments of the present invention, the coupled voltage detecting circuit is coupled to the common voltage terminal T _{VCOM of the} display module 200 and detects the coupled voltage V _FD . The coupled voltage detecting circuit can also be coupled to the source driving. The circuit detects the coupling voltage of the data line or is coupled to the source driving circuit and the common voltage terminal T _VCOM . Please refer to FIG. 4, which is a schematic diagram of a liquid crystal display device 40 according to another embodiment of the present invention. In FIG. 4, the liquid crystal display device 40 includes a display module 400, a source driving circuit 420, a gate driving circuit 440, and a voltage calibration circuit 450. The voltage calibration circuit 450 includes a coupled voltage detection circuit 460, a common voltage circuit 480, and a switch 490. The display device 40 differs from the liquid crystal display device 20 in that the coupling relationship of the switch 490 is different from that of the switch 290. The switch 490 is coupled to the display module 400, the source driving circuit 420, and the coupled voltage detecting circuit 460 for controlling the display module 400 to be coupled to the source driving circuit 420 or the coupling voltage detecting circuit 460. When the gate driving circuit 440 turns off the gate line, the switch 490 controls the common voltage terminal T _{VCOM of the} display module 400 to be coupled to the coupled voltage detecting circuit 460, and the coupled voltage detecting circuit 460 detects the coupling voltage of the data line V. _{The FD_source} and the compensation voltage V _{SHFT are} generated according to the coupling voltage V _{FD — source} . Preferably, the coupling voltage _V FD_source data line is about the same as the common voltage terminal is coupled T _VCOM voltage V _FD. During the display period, the switch 490 controls the display module 400 to be coupled to the source driving circuit 420. The common voltage circuit 480 adjusts the common voltage Vcom according to the compensation voltage V _SHFT and outputs the common voltage Vcom to the display module 400.

Please refer to FIG. 5. FIG. 5 is a schematic diagram of a liquid crystal display device 50 according to another embodiment of the present invention. The liquid crystal display device 50 includes a display module 500, a source driving circuit 520, a gate driving circuit 540, and a voltage calibration circuit 550. The voltage calibration circuit 550 includes a coupled voltage detection circuit 560, a common voltage circuit 580, a voltage setting unit 510, a first switch 590, and a second switch 591. The voltage calibration circuit 550 incorporates the voltage calibration circuit 350 and the voltage calibration circuit 450, and thus the basic architecture is substantially the same, the only difference being that the voltage calibration circuit 550 includes a second switch 591. The first switch 590 is coupled to the display module 500, the source driving circuit 520, and the coupled voltage detecting circuit 560 for controlling the display module 500 to be coupled to the source driving circuit 520 or the coupled voltage detecting circuit 560. The second switch 591 is coupled to the display module 500, the common voltage circuit 580, and the coupled voltage detecting circuit 560 for controlling the display module 500 to be coupled to the common voltage circuit 580 or the coupled voltage detecting circuit 560. When the gate driving circuit 540 turns off the gate line, the first switch 590 controls the display module 500 to be coupled to the coupled voltage detecting circuit 560, and the second switch 591 controls the common voltage terminal T _{VCOM of the} display module 500 to be coupled to Detection circuit 560. That is, the coupled voltage detecting circuit 560 simultaneously detects the coupling voltage V _{FD —} source of the data line of the display module 500 and the coupling voltage V _FD of the common voltage terminal T _VCOM , and generates compensation according to the coupling voltages V _FD and V _{FD — source} . Voltage V _SHFT . During the display period, the first switch 590 controls the display module 500 to be coupled to the source driving circuit 520, and the second switch 591 controls the common voltage terminal T _{VCOM of the} display module 500 to be coupled to the common voltage circuit 580, the common voltage circuit 580. The common voltage Vcom is adjusted according to the offset preset value of the common voltage Vcom and the compensation voltage V _SHFT , and the common voltage Vcom is output to the display module 500.

Please refer to FIG. 6A. FIG. 6A is a schematic diagram of a liquid crystal display device 60 according to an embodiment of the present invention. The liquid crystal display device 60 includes a display module 600, a gate driving circuit 640, and a voltage calibration circuit 650. The voltage calibration circuit 650 includes a source driving circuit 620, a coupling voltage detecting circuit 660, and a switch 690. The structure of the liquid crystal display device 60 is similar to that of the thin film transistor liquid crystal display device 10 of FIG. 1, and therefore the same portions will not be described again. The gate driving circuit 640 is configured to generate a plurality of gate signals to turn on/off the plurality of gate lines. When the display module 600 is at the falling edge of the plurality of gate signals (ie, the plurality of gate lines are turned off), the parasitic capacitance of the display module 600 generates a coupling voltage V _FD . The switch 690 is coupled to the coupled voltage detecting circuit 660 for controlling the display module 600 to be coupled to a ground terminal 680 or a coupled voltage detecting circuit 660. When a common voltage terminal T _{VCOM of the} display module 600 is coupled to the ground terminal 680, the common voltage Vcom is fixed to 0V. The coupled voltage detection circuit 660 is coupled to the common voltage terminal T _{VCOM of the} display module 600 through the switch 690. The coupling voltage detecting circuit 660 is configured to detect the coupling voltage V _FD in an initial period of the liquid crystal display device 60 and generate a compensation voltage V _SHFT according to the coupling voltage V _FD . The initial period of the liquid crystal display device 60 is one of the periods before the liquid crystal display device 60 is turned on. The source driving circuit 620 is configured to output an unadjusted display voltage Vcs' to the display module 600 in an initial period and output a display voltage Vcs to the display module 600 according to the compensation voltage V _SHFT in a display period. Therefore, the liquid crystal display device 60 of the embodiment of the present invention can detect the coupling voltage V _FD generated by the parasitic capacitance in the initial period of the liquid crystal display device 60, and actively adjust the display voltage to avoid flickering without burning. Actions to reduce process time and increase unit capacity.

Please refer to FIG. 6B at the same time. FIG. 6B is a waveform diagram of a display unit according to an embodiment of the present invention. In an initial period, the common voltage Vcom is preset to an initial voltage value (for example, 0V), and the source driver 620 outputs the unregulated display voltage Vcs' to the plurality of storage capacitors of the display module 600. When the gate driving circuit 640 turns off the gate line (ie, from the positive potential VGH to the negative potential VGL), the switch 690 controls the common voltage terminal T _{VCOM of the} display module 600 to be coupled to the coupled voltage detecting circuit 660. The coupled voltage detecting circuit 660 detects the coupled voltage V _FD and generates a compensation voltage V _SHFT according to the coupling voltage V _FD . Preferably, the coupling voltage V _FD can be stored in a register of the coupled voltage detecting circuit 660 (not shown in FIG. 6A). During the display period, the switch 690 controls the common voltage terminal T _{VCOM of the} display module 600 to be coupled to the ground point 680 such that the common voltage Vcom of the common voltage terminal T _VCOM is fixed to 0V. The coupled voltage detecting circuit 660 outputs the compensation voltage V _SHFT to the source driving circuit 620. The source driving circuit 620 outputs the display voltage Vcs to the display module in the display period according to the compensation voltage V _SHFT .

In an embodiment of the invention, the voltage calibration circuit may further comprise a voltage setting unit. Please refer to FIG. 7. FIG. 7 is a schematic diagram of a liquid crystal display device 70 according to another embodiment of the present invention. In FIG. 7, the liquid crystal display device 70 includes a display module 700, a gate driving circuit 740, and a voltage calibration circuit 750. The voltage calibration circuit 750 includes a source driving circuit 720, a coupled voltage detecting circuit 760, a switch 790, and a voltage setting unit 710. The basic structure of the display device 70 is similar to that of the display device 60. The voltage setting unit 710 is coupled to the coupled voltage detecting circuit 760 and the source driving circuit 720 for setting a preset value of the display voltage offset. When the gate driving circuit 740 turns off the gate line, the switch 790 controls the common voltage terminal T _{VCOM of the} display module 700 to be coupled to the coupled voltage detecting circuit 760. The coupled voltage detecting circuit 760 detects the coupling voltage V _FD and generates a compensation voltage V _SHFT according to the coupling voltage V _FD . During the display period, the switch 790 controls the common voltage terminal T _{VCOM of the} display module 700 to be coupled to the ground terminal 780. The source driving circuit 720 compares and multiplies the offset preset value and the compensation voltage V _SHFT to adjust the display voltage Vcs'. The adjusted display voltage Vcs is output to the display module 700 during the display period.

In other embodiments of the present invention, the coupled voltage detecting circuit is coupled to the common voltage terminal T _{VCOM of the} display modules 600 and 700 and detects the coupled voltage V _FD . The coupled voltage detecting circuit can also be coupled to the source. The pole drive circuit detects the coupling voltage of the data line or is coupled to the source drive circuit and the common voltage terminal T _VCOM . Please refer to FIG. 8. FIG. 8 is a schematic diagram of a liquid crystal display device 80 according to another embodiment of the present invention. In FIG. 8, the liquid crystal display device 80 includes a display module 800, a gate driving circuit 840, and a voltage calibration circuit 850. The voltage calibration circuit 850 includes a source driving circuit 820, a coupled voltage detecting circuit 860, and a switch 890. The liquid crystal display device 80 is different in that the coupling relationship of the switch 890 is different from that of the switch 690, and the display module 800 is directly coupled to a ground terminal 880. The switch 890 is coupled to the display module 800, the source driving circuit 820, and the coupled voltage detecting circuit 860 for controlling the display module 800 to be coupled to the source driving circuit 820 or the coupled voltage detecting circuit 860. When the gate driving circuit 840 turns off the gate line, the switch 890 controls the display module 800 to be coupled to the coupled voltage detecting circuit 860. Next, the coupled voltage detecting circuit 860 detects the coupled voltage V _{FD —} source of the data line and generates a compensation voltage V _SHFT according to the coupled voltage V _{FD — source} . Preferably, the coupling voltage _V FD_source data line is about the same as the common voltage terminal is coupled T _VCOM voltage V _FD. During the display period, the switch 890 controls the display module 800 to be coupled to the source driving circuit 820. The source driving circuit 820 adjusts the display voltage Vcs' according to the compensation voltage V _SHFT and outputs the display voltage Vcs to the display module 800 during the display period.

Please refer to FIG. 9. FIG. 9 is a schematic diagram of a liquid crystal display device 90 according to another embodiment of the present invention. The liquid crystal display device 90 includes a display module 900, a gate driving circuit 940, and a voltage calibration circuit 950. The voltage calibration circuit 950 includes a source driving circuit 920, a coupling voltage detecting circuit 960, a grounding terminal 980, a voltage setting unit 910, a first switch 990, and a second switch 991. The liquid crystal display device 90 incorporates the liquid crystal display device 70 and the liquid crystal display device 80, and thus the basic architecture is substantially the same, the only difference being that the voltage calibration circuit 950 includes a second switch 991. The first switch 990 is coupled to the display module 900, the source driving circuit 920, and the coupled voltage detecting circuit 960 for controlling the display module 900 to be coupled to the source driving circuit 920 or the coupling voltage detecting circuit 960. The second switch 991 is coupled to the display module 900, the grounding terminal 980, and the coupled voltage detecting circuit 960 for controlling the common voltage terminal T _{VCOM of the} display module 900 to be coupled to a ground terminal 980 or a coupled voltage detecting circuit. 960. When the gate driving circuit 940 turns off the gate line, the first switch 990 controls the display module 900 to be coupled to the coupled voltage detecting circuit 960, and the second switch 991 controls the common voltage terminal T _{VCOM of the} display module 900 to be coupled to Detection circuit 960. That is, the coupled voltage detecting circuit 960 simultaneously detects the coupling voltage V _{FD —} source of the data line of the display module 900 and the coupling voltage V _FD of the common voltage terminal T _VCOM , and according to the coupling voltage V _FD and the coupling voltage V _{FD — source} , A compensation voltage V _{SHFT is generated} . During the display period, the first switch 990 controls the display module 900 to be coupled to the source driving circuit 920, and the second switch 991 controls the common voltage terminal T _{VCOM of the} display module 900 to be coupled to the ground terminal 980, so that the common voltage Vcom is fixed. It is 0V. The source driver 920 compares the offset preset value and the compensation voltage V _{SHFT to} adjust the display voltage Vcs', and outputs the display voltage Vcs to the display module 900 during the display period.

In summary, the coupling voltage circuit of the embodiment of the present invention can actively detect the coupling voltage (the coupling voltage of the data line or the common voltage end point) generated by the parasitic capacitance in the initial period, and adjust the voltage value of the common voltage according to the coupling voltage. To avoid flickering caused by the difference in coupling voltage. Compared with the prior art, the invention does not need to perform the burning operation, which can reduce the processing time and increase the unit throughput.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

Vcom‧‧‧Common voltage

20‧‧‧Liquid crystal display device

220‧‧‧Source drive circuit

240‧‧‧ gate drive circuit

250‧‧‧Voltage calibration circuit

260‧‧‧Coupled voltage detection circuit

280‧‧‧Common voltage circuit

290‧‧‧ switch

V _FD ‧‧‧Coupling voltage

T _VCOM ‧‧‧Common voltage endpoint

V _{SHFT ‧‧‧compensation} voltage

Claims (16)

A voltage calibration circuit includes: a coupled voltage detecting circuit for detecting a coupling voltage during an initial period and generating a compensation voltage according to the coupling voltage; and a common voltage circuit for using a display period according to the The compensation voltage adjusts a common voltage and outputs the common voltage to a display module. The voltage calibration circuit of claim 1, further comprising a switch coupled to the common voltage circuit and the coupled voltage detecting circuit for controlling the display module to be coupled to the common voltage circuit or the coupling voltage Detection circuit. The voltage calibration circuit of claim 2, wherein the switch couples the display module to the coupled voltage detection circuit during the initial period. The voltage calibration circuit of claim 2, wherein the switch couples the display module to the common voltage circuit during the display period. The voltage calibration circuit of claim 1, further comprising a switch coupled to a source driving circuit and the coupled voltage detecting circuit for controlling the display module to be coupled to the source driving circuit or the Coupling voltage detection circuit. The voltage calibration circuit of claim 1, further comprising: a first switch coupled to a source driving circuit and the coupled voltage detecting circuit for controlling the display module to be coupled to the source driving a circuit or the coupled voltage detecting circuit; and a second switch coupled to the common voltage circuit and the coupled voltage detecting circuit for controlling The display module is coupled to the common voltage circuit or the coupled voltage detecting circuit. The voltage calibration circuit of claim 1, further comprising a voltage setting unit coupled to the coupled voltage detecting circuit and the common voltage circuit for setting a preset offset value of the common voltage. A liquid crystal display device includes a display module including a plurality of stray capacitances, a gate driving circuit for generating a plurality of gate signals, and a source driving circuit coupled to the display module. And a voltage calibration circuit, comprising: a coupled voltage detecting circuit for detecting a coupling voltage during an initial period and generating a compensation voltage according to the coupling voltage; A common voltage circuit is configured to adjust a common voltage according to the compensation voltage and output the common voltage to the display module during a display period. A voltage calibration circuit includes: a coupled voltage detecting circuit for detecting a coupling voltage during an initial period and generating a compensation voltage according to the coupling voltage; and a source driving circuit for using a display period according to a display period The compensation voltage outputs a display voltage to a display module. The voltage calibration circuit of claim 9, further comprising a switch coupled to the coupled voltage detecting circuit for controlling the display module to be coupled to a ground or the coupled voltage detecting circuit. The voltage calibration circuit of claim 10, wherein the switch couples the display module to the coupled voltage detection circuit during the initial period. The voltage calibration circuit of claim 10, wherein the switch couples the display module to the ground during the display period. The voltage calibration circuit of claim 9, further comprising a switch coupled to the source driving circuit and the coupled voltage detecting circuit for controlling the display module to be coupled to the source driving circuit or the Coupling voltage detection circuit. The voltage calibration circuit of claim 9, further comprising: a first switch coupled to the source driving circuit and the coupled voltage detecting circuit for controlling the display module to be coupled to the source driving The circuit or the coupled voltage detecting circuit; and a second switch coupled to the coupled voltage detecting circuit for controlling the display module to be coupled to a ground or the coupled voltage detecting circuit. The voltage calibration circuit of claim 9, further comprising a voltage setting unit coupled to the coupling voltage detecting circuit and the source driving circuit for setting a deviation of the display voltage by a preset value. A liquid crystal display device comprises: a display module comprising a plurality of stray capacitances; a gate drive circuit for generating a plurality of gate signals; and a voltage calibration circuit comprising: a coupled voltage detection a circuit for detecting a coupling voltage during an initial period and according to The coupling voltage generates a compensation voltage; and a source driving circuit is configured to output a display voltage to the display module according to the compensation voltage during a display period.