Display driving circuit and display device

Abstract

The application discloses a display driving circuit and a display device. The display driving circuit comprises a source driving chip and a gamma chip. The source driving chip comprises a plurality of source signal driving modules, a first short circuit module, a first comparator, a second comparator and a logic judgment module. The source signal driving module comprises a first switch. The first short circuit module comprises a second switch and a plurality of third switches. The receiving end of the logic judgment module is connected with the output ends of the first comparator and the second comparator. The output end of the logic judgment module is connected with the control ends of the first switch, the second switch and the third switches. The opening and closing of the first switch, the second switch and the third switches are controlled according to the output results of the first comparator and the second comparator. Through the above design, the problem of large current extraction and short-term voltage difference of the common electrode signal and the source driving signal in the process of power-on and power-off can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, and in particular to a display driving circuit and a display device. BACKGROUND

[0002] With the increasing requirements of consumers on liquid crystal display panels, the terminal manufacturers are more and more intolerant to the instantaneous flicker phenomenon of the liquid crystal display panel when it is powered on and powered off. This situation makes the source driver manufacturers design a power on / off reset function (POF) when designing the driving chip, so as to short all the output channels of the source driving chip together when the power is on or off, and then short them to the common electrode signal channel (CFVCOM) or the system ground (VSS), so as to release the charges in the liquid crystal display panel as much as possible and ensure the consistency of the voltage between the electrodes (pixel electrode and common electrode) on both sides of the liquid crystal.

[0003] However, with the current power on / off reset function design, a large extraction current will appear in the process of powering on and powering off the liquid crystal display panel, and the common electrode signal and the source driving signal will have a temporary voltage difference, which will cause the liquid crystal display panel to flicker. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a display driving circuit and a display device to improve the problem of large extraction current and temporary voltage difference of the common electrode signal and the source driving signal in the process of powering on and powering off.

[0005] The embodiment of the present application discloses a display driving circuit, which comprises a source driving chip and a gamma chip, the gamma chip is connected with the source driving chip through a plurality of gamma channels and a common electrode signal channel, the source driving chip comprises a plurality of source signal driving modules, a first short circuit module, a first comparator, a second comparator and a logic judgment module, the source signal driving module comprises a first switch, the input end of the first switch is connected with the corresponding gamma channel, and the output end of the first switch is connected with the corresponding data line in the display panel; the first short circuit module comprises a second switch and a plurality of third switches, the input end of the second switch is connected with the common electrode signal channel, and the output end of the second switch is connected with the corresponding source signal driving module through the third switch; the positive input end of the first comparator receives a reference voltage, and the negative input end of the first comparator receives a power supply voltage; the positive input end of the second comparator receives the power supply voltage, and the negative input end of the second comparator receives a first standard voltage; the receiving end of the logic judgment module is connected with the output end of the first comparator and the output end of the second comparator, the output end of the logic judgment module is connected with the control ends of the first switch, the second switch and the third switch, and the opening and closing of the first switch, the second switch and the third switch are controlled according to the output results of the first comparator and the second comparator; wherein the first standard voltage is the voltage when the display panel is in the initial stage of power-on or the voltage when the display panel is in the last stage of power-off.

[0006] Optionally, when the power supply voltage is less than the first standard voltage, the logic judgment module controls the second switch and the third switch to be opened, and controls the first switch to be disconnected.

[0007] Optionally, the display driving circuit further comprises a second short circuit module, the second short circuit module comprises a fourth switch and a plurality of fifth switches, the input end and the output end of each fifth switch are connected with adjacent two source signal driving modules respectively, and all the fifth switches are grounded through the fourth switch; the output end of the logic judgment module is further connected with the control ends of the fourth switch and the fifth switch, and the opening and closing of the first switch, the second switch, the third switch, the fourth switch and the fifth switch are controlled according to the output results of the first comparator and the second comparator.

[0008] Optionally, when the power supply voltage is less than the first standard voltage, the logic judgment module controls the second switch and the third switch to be opened, and controls the first switch to be disconnected; or when the power supply voltage is less than the first standard voltage, the logic judgment module controls the second switch, the third switch, the fourth switch and the fifth switch to be opened, and controls the first switch to be disconnected.

[0009] Optionally, the display driving circuit further comprises a third comparator, a positive input end of the third comparator receives the power supply voltage, a negative input end of the third comparator receives a second standard voltage, the second standard voltage is a voltage when the display panel is in a power-on secondary stage or a voltage when the display panel is in a power-off penultimate stage; an output end of the third comparator is connected with a receiving end of the logic judgment module, the logic judgment module controls opening and closing of the first switch, the second switch, the third switch, the fourth switch and the fifth switch according to output results of the first comparator, the second comparator and the third comparator.

[0010] Optionally, when the reference voltage is less than the power supply voltage and the power supply voltage is less than the first standard voltage, the logic judgment module controls the second switch and the third switch to be opened, and controls the first switch, the fourth switch and the fifth switch to be turned off at the same time; when the reference voltage is less than the power supply voltage, the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic judgment module controls the second switch, the third switch, the fourth switch and the fifth switch to be opened, and controls the first switch to be turned off at the same time; when the reference voltage is less than the power supply voltage, the power supply voltage is greater than the second standard voltage, the logic judgment module controls the fourth switch and the fifth switch to be opened, and controls the first switch, the second switch and the third switch to be turned off at the same time; when the reference voltage is greater than the power supply voltage and the power supply voltage is less than the first standard voltage, the logic judgment module controls the second switch and the third switch to be opened, and controls the first switch, the fourth switch and the fifth switch to be turned off at the same time; when the reference voltage is greater than the power supply voltage, the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic judgment module controls the second switch, the third switch, the fourth switch and the fifth switch to be opened, and controls the first switch to be turned off at the same time; when the reference voltage is greater than the power supply voltage, the power supply voltage is greater than the second standard voltage, the logic judgment module controls the first switch to be opened, and controls the second switch, the third switch, the fourth switch and the fifth switch to be turned off at the same time.

[0011] Optionally, the first short circuit module further comprises a sixth switch, an input end of the sixth switch is connected with the input end of the second switch, an output end of the sixth switch is grounded, and a control end of the sixth switch is connected with the output end of the logic judgment module; the logic judgment module controls the opening and closing of the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch according to the output results of the first comparator, the second comparator and the third comparator; when the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic judgment module controls the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch to be opened, and controls the first switch to be closed at the same time; when the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the second standard voltage, the logic judgment module controls the fourth switch, the fifth switch and the sixth switch to be opened, and controls the first switch, the second switch and the third switch to be closed at the same time; when the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic judgment module controls the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch to be opened, and controls the first switch to be closed at the same time.

[0012] Optionally, the first short circuit module further comprises a first resistor, and the input end of the second switch is connected with the common electrode signal channel through the first resistor.

[0013] Optionally, the gamma chip is connected with the source driving chip through n gamma channels and a common electrode signal channel; the gamma chip comprises a fourth comparator, a positive input end of the fourth comparator receives a power supply voltage, a negative input end of the fourth comparator receives a third standard voltage, and an output end of the fourth comparator is connected with a receiving end of the logic judgment module; wherein the third standard voltage is 70% of the power supply voltage; the gamma chip further comprises n seventh switches and n-1 eighth switches, the gamma channels and the common electrode signal channel are connected with the source driving chip through the corresponding seventh switches; adjacent two gamma channels are connected through an eighth switch, and the common electrode signal channel and adjacent gamma channels are also connected through an eighth switch; control ends of the seventh switches and the eighth switches are connected with an output end of the logic judgment module, and the logic judgment module controls the opening and closing of the seventh switches and the eighth switches according to the output result of the fourth comparator.

[0014] The display device includes a display panel and the display driving circuit as described above, and the display driving circuit is used for driving the display panel.

[0015] The display driving circuit as described above is used for driving the display panel. The beneficial effects of the embodiments of the present application are as follows: the embodiments of the present application set the source signal driving module, the first short-circuit module, the first comparator, the second comparator and the logic judgment module in the source driving chip of the display driving circuit, the logic judgment module judges whether the power-on or power-off state is at this moment according to the comparison result of the reference voltage and the power supply voltage by the first comparator, and at the same time, the logic judgment module judges which stage of the power-on or power-off is at this moment according to the comparison result of the power supply voltage and the first standard voltage by the second comparator, and the logic judgment module controls the switches in the source signal driving module and the first short-circuit module according to the comprehensive result of the first comparator and the second comparator, so that the ports corresponding to the gamma channel and the common electrode signal channel in the source driving chip can be short-circuited in different stages of the power-on or power-off, the rapid discharge of the common electrode and the pixel electrode is realized, and the problems of large current draw and short-term voltage difference of the common electrode signal and the source driving signal are avoided. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings included to provide a further understanding of the embodiments of the present application, constitute a part of the specification and serve to explain the principles of the present application together with the text. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings:

[0017] Figure 1 is a schematic diagram of a driving chip provided by the present application;

[0018] Figure 2 is a schematic diagram of a display driving circuit provided by the present application based on the structure in the power-on process; Figure 1

[0019] Figure 3 is a schematic diagram of a display driving circuit provided by the present application based on the structure in the power-off process; Figure 1

[0020] Figure 4 is a schematic diagram of a display driving circuit provided by the first embodiment of the present application;

[0021] Figure 5 is a schematic diagram of a display driving circuit provided by the second embodiment of the present application;

[0022] Figure 6 is a schematic diagram of a display driving circuit provided by the third embodiment of the present application;​

[0023] Figure 7 is a timing diagram provided by a third embodiment of the present application;

[0024] Figure 8 is a schematic diagram of a display driving circuit provided by a fourth embodiment of the present application;

[0025] Figure 9 is a schematic diagram of another display driving circuit provided by the present application;

[0026] Figure 10 is a schematic diagram of a display device provided by the present application.

[0027] wherein, 10, display device; 20, display driving circuit; 30, display panel; 100, source driving chip; 110, source signal driving module; 120, first short-circuit module; 130, first comparator; 140, second comparator; 150, logic judgment module; 160, second short-circuit module; 170, third comparator; R1, first resistor; T1, first switch; T2, second switch; T3, third switch; T4, fourth switch; T5, fifth switch; T6, sixth switch; m1, first standard voltage; m2, second standard voltage; 200, gamma chip; 210, low dropout linear regulator; 220, resistor voltage dividing module; 230, fourth comparator; 240, gamma channel; 250, common electrode signal channel; T7, seventh switch; T8, eighth switch; m3, third standard voltage. DETAILED DESCRIPTION

[0028] It should be understood that the terms, specific structures and functional details used herein are merely to describe specific embodiments and are representative, but the present application can be embodied in many alternative forms, and should not be interpreted as being limited to the embodiments set forth herein.

[0029] In addition, unless otherwise explicitly specified and limited, "connected", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] Figure 1 is a schematic diagram of a source driving chip provided by the present application, such as Figure 1As shown, the source driving chip 100 includes a plurality of source signal driving modules 110, a first shorting module 120, a second shorting module 160, a comparator and a logic decision module 150. The source signal driving module 110 includes a first switch T1, an input end of the first switch T1 is connected with the gamma channel 240 in correspondence, and an output end of the first switch T1 is connected with a data line in the display panel 30 in correspondence. The first shorting module 120 includes a second switch T2 and a plurality of third switches T3, an input end of the second switch T2 is connected with the common electrode signal channel 250 through a first resistor R1, and output ends of the second switch T2 are respectively connected with corresponding source signal driving modules 110 through the third switches T3. The second shorting module 160 includes a fourth switch T4 and a plurality of fifth switches T5, an input end and an output end of each fifth switch T5 are respectively connected with adjacent two source signal driving modules 110, and all fifth switches T5 are grounded through the fourth switch T4. A positive input end of the comparator receives a power voltage (DVDD), and a negative input end of the second comparator 140 receives a first standard voltage m1. A receiving end of the logic decision module 150 is connected with an output end of the comparator, and output ends of the logic decision module 150 are connected with control ends of the first switch T1, the second switch T2 and the third switch T3, and the opening and closing of the first switch T1, the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 are controlled according to the output result of the comparator.

[0031] Wherein, the power voltage (DVDD) is a direct current voltage (generally 1.8V) supplied to the digital circuit of the source driving chip 100 (Source driver), and the source driving chip 100 judges whether it is in the power on or power off state by detecting the voltage of DVDD. When DVDD is less than 0.9V, it is judged that it is in the initial stage of power on or power off, the comparator outputs low level, the first switch T1 in the source signal driving module 110 is disconnected, and the output port of the source driving chip 100 is turned off to output the voltage of the data line in the display panel 30. At the same time, the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 are turned on, and all output ports of the source driving chip 100 are shorted together and then shorted to the common electrode signal channel 250 and the ground line. The first resistor R1 is a resistance of about 1000Ω, which is used to prevent large current surge.

[0032] It can be understood that, for the convenience of display, only two source signal driving modules 110 are shown in the figure, which correspond to the output port Yn and the output port Yn+1 of the source driving chip 100 respectively.

[0033] In combination withFigure 1 and Figure 2 As shown in FIG. 1 and FIG. 2, when the display panel 30 is powered on, the DVDD rises from 0V to 0.9V, the first switch T1 of the source driving chip 100 is turned off, and the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 are turned on, so that the output ports of the source driving chip 100 are all short-circuited to the common electrode signal line and the ground line (VSS). Since the common electrode signal line is powered at almost the same time as the DVDD, the common electrode signal voltage starts to rise at the same time as the DVDD. Since the common electrode signal line and the ground line, and the output ports of the source driving chip 100 are short-circuited together, the output port voltage of the source driving chip 100 is also pulled up at the same time. At this time, the common electrode signal line has a relatively large current draw (the current draw will cause the power supply of the common electrode signal line to overheat). Moreover, since the resistance value of the first resistor R1 is relatively large, there is a difference in the ramping speed of the common electrode signal voltage and the output port voltage of the source driving chip 100, which causes a voltage drop between the common electrode signal voltage and the output port voltage of the source driving chip 100 during the ramping period, and a short-time flicker phenomenon occurs at this moment.

[0034] In combination with Figure 1 and Figure 3 As shown in FIG. 1 and FIG. 2, when the display panel 30 is powered off, when the DVDD is adjusted to below 0.9V, since the common electrode signal line and the ground line, and the output ports of the source driving chip 100 are short-circuited together, the common electrode signal line and the output ports of the source driving chip 100 all start to power down. However, since the ground is close to the output ports of the source driving chip 100, the output ports of the source driving chip 100 power down faster, so there is a certain voltage difference between the common electrode signal line and the output ports of the source driving chip 100 at this time, which causes a relatively fast flicker phenomenon.

[0035] As can be seen, after the driving circuit structure of Figure 1 is adopted, when the display panel 30 is powered on, the common electrode signal line has a relatively large current draw, and there is a voltage drop between the common electrode signal voltage and the output port voltage of the source driving chip 100; and when the display panel 30 is powered off, there is a short-time voltage difference between the common electrode signal line and the output ports of the source driving chip 100, which all cause the display panel 30 to flicker.

[0036] Based on the above problems, the present application provides the following specific embodiments to improve the problems of the relatively large current draw and the short-time voltage difference between the common electrode signal and the source driving signal during the power-on and power-off processes.

[0037] Embodiment one:

[0038] As shown in FIG. 3, the first switch T1 of the source driving chip 100 is turned on, and the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 are turned off, so that the output ports of the source driving chip 100 are all short-circuited to the common electrode signal line and the ground line (VSS). Since the common electrode signal line is powered at almost the same time as the DVDD, the common electrode signal voltage starts to rise at the same time as the DVDD. Since the common electrode signal line and the ground line, and the output ports of the source driving chip 100 are short-circuited together, the output port voltage of the source driving chip 100 is also pulled up at the same time. At this time, the common electrode signal line has a relatively large current draw (the current draw will cause the power supply of the common electrode signal line to overheat). Moreover, since the resistance value of the first resistor R1 is relatively large, there is a difference in the ramping speed of the common electrode signal voltage and the output port voltage of the source driving chip 100, which causes a voltage drop between the common electrode signal voltage and the output port voltage of the source driving chip 100 during the ramping period, and a short-time flicker phenomenon occurs at this moment. Figure 4As shown, the first embodiment of the present application provides a display driving circuit, which comprises a source driving chip 100 and a gamma chip 200, the gamma chip 200 is connected with the source driving chip 100 through a plurality of gamma channels 240 and a common electrode signal channel 250, the gamma channel 240 is used for outputting a data driving signal, the data driving signal is output to a data line through a source driving circuit, and finally output to a pixel electrode through the data line; the common electrode signal channel 250 is used for transmitting a common voltage signal, and the common voltage signal is used for output to a common electrode; in the display panel 30, an electric field is formed between the pixel electrode and the common electrode, and the liquid crystal is deflected.

[0039] The source driving chip 100 comprises a plurality of source signal driving modules 110, a first short circuit module 120, a first comparator 130, a second comparator 140 and a logic judgment module 150, the source signal driving module 110 comprises a first switch T1, the input end of the first switch T1 is connected with the corresponding gamma channel 240, the output end of the first switch T1 is connected with the corresponding data line in the display panel 30, and the output end of the first switch T1 is the output port of the source driving chip 100.

[0040] The first short circuit module 120 comprises a second switch T2 and a plurality of third switches T3, the input end of the second switch T2 is connected with the common electrode signal channel 250, the output end of the second switch T2 is connected with the corresponding source signal driving module 110 through the third switch T3; the positive input end of the first comparator 130 receives a reference voltage (AVDD), and the negative input end of the first comparator 130 receives a power voltage (DVDD); the positive input end of the second comparator 140 receives a power voltage, and the negative input end of the second comparator 140 receives a first standard voltage m1; the receiving end of the logic judgment module 150 is connected with the output end of the first comparator 130 and the output end of the second comparator 140, and the output end of the logic judgment module 150 is connected with the control end of the first switch T1, the second switch T2 and the third switch T3, and the opening and closing of the first switch T1, the second switch T2 and the third switch T3 are controlled according to the output results of the first comparator 130 and the second comparator 140.

[0041] Among them, the first standard voltage m1 is the voltage when the display panel 30 is in the initial stage of power-on or the voltage when the display panel 30 is in the last stage of power-off. The voltage of the power voltage can be 1.8V, and the voltage of the first standard voltage m1 can be 0.9V.

[0042] In the embodiment of the present application, the display driving circuit 20 has only one short-circuit module, i.e., the first short-circuit module 120; and the display driving circuit 20 also has only two comparators, i.e., the first comparator 130 and the second comparator 140.

[0043] In the first short-circuit module 120, the number of the third switches T3 is the same as the number of the output ports in the source driving chip 100, and is also the same as the number of the source signal driving modules 110 in the source driving chip 100. The output end of each third switch T3 is connected with a corresponding source signal driving module 110.

[0044] In each source signal driving module 110, an amplifier is further included, and the input end of the first switch T1 is connected with the corresponding gamma channel 240 through the amplifier.

[0045] In the embodiment of the present application, when the power supply voltage is less than the first standard voltage m1, the logic judgment module 150 controls the second switch T2 and the third switch T3 to be opened, and controls the first switch T1 to be disconnected.

[0046] In the embodiment of the present application, the source signal driving module 110, the first short-circuit module 120, the first comparator 130, the second comparator 140 and the logic judgment module 150 are arranged in the source driving chip 100 of the display driving circuit 20. The logic judgment module 150 judges whether the current state is the power-on state or the power-off state according to the comparison result of the reference voltage and the power supply voltage by the first comparator 130, judges which stage of the power-on or power-off the current state is according to the comparison result of the power supply voltage and the first standard voltage m1 by the second comparator 140, and controls the switches in the source signal driving module 110 and the first short-circuit module 120 according to the comprehensive result of the first comparator 130 and the second comparator 140. Therefore, the corresponding port in the source driving chip 100 corresponding to the gamma channel 240 and the common electrode signal channel 250 can be short-circuited in different stages of the power-on or power-off, the rapid discharge of the common electrode and the pixel electrode is realized, and the problems of large current inrush and short-time voltage difference of the common electrode signal and the source driving signal are avoided.

[0047] In the embodiment of the present application, the first short-circuit module 120 further includes a first resistor R1, and the input end of the second switch T2 is connected with the common electrode signal channel 250 through the first resistor R1. The first resistor R1 is 800-1200 ohms, and is used for preventing large current inrush.

[0048] Second embodiment:

[0049] As Figure 5As shown, as a display driving circuit provided in the second embodiment of this application, the display driving circuit 20 further includes a second shorting module 160 based on the first embodiment. The second shorting module 160 includes a fourth switch T4 and a plurality of fifth switches T5. The input and output terminals of each fifth switch T5 are respectively connected to two adjacent source signal driving modules 110, and all the fifth switches T5 are grounded through the fourth switch T4. The output terminal of the logic determination module 150 is also connected to the control terminals of the fourth switch T4 and the fifth switches T5, and controls the opening and closing of the first switch T1, the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 according to the output results of the first comparator 130 and the second comparator 140.

[0050] In this embodiment of the application, when the power supply voltage is less than the first standard voltage m1, the logic determination module 150 controls the second switch T2 and the third switch T3 to open, and controls the first switch T1 to open; or, when the power supply voltage is less than the first standard voltage m1, the logic determination module 150 controls the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 to open, and controls the first switch T1 to open.

[0051] In this embodiment of the application, not only can all output ports of the source driver chip 100 and the common electrode signal channel 250 be shorted together during power-on and power-off, but they can also be further shorted to the ground line, which makes the discharge effect better and further avoids the problem of flickering of the display panel 30.

[0052] Third embodiment:

[0053] like Figure 6 As shown, as a display driving circuit provided in the third embodiment of this application, the display driving circuit 20 further includes a third comparator 170 based on the second embodiment. The positive input terminal of the third comparator 170 receives a power supply voltage, and the negative input terminal of the third comparator 170 receives a second standard voltage m2. The second standard voltage m2 is the voltage of the display panel 30 in the power-on secondary stage or the voltage of the display panel 30 in the penultimate power-off stage. The output terminal of the third comparator 170 is connected to the receiving terminal of the logic determination module 150. The logic determination module 150 controls the opening and closing of the first switch T1, the second switch T2, the third switch T3, the fourth switch T4, and the fifth switch T5 according to the output results of the first comparator 130, the second comparator 140, and the third comparator 170.

[0054] The first standard voltage m1 can be 0.9V, and the second standard voltage m2 can be 1.1V.

[0055] A1 A2 A3 Open switch 0 0 0 T2, T3 0 0 1 T2, T3, T4, T5 0 1 1 T4, T5 1 0 0 T2, T3 1 0 1 T2, T3, T4, T5 1 1 1 T1

[0056] Table 1

[0057] In combination Figure 6 , Figure 7 When the reference voltage is less than the power supply voltage, and the power supply voltage is less than the first standard voltage m1, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=000 at this time, which can be understood as the initial stage of power-on or the last stage of power-off, and the electric quantity of the pixel electrode and the common electrode on the display panel 30 is relatively small at this time. In this regard, the logic judgment module 150 controls the second switch T2 and the third switch T3 to be opened, and controls the first switch T1, the fourth switch T4 and the fifth switch T5 to be disconnected, so that the output ports of the source driving chip 100 are short-circuited together and are short-circuited with the common electrode and the common electrode signal channel 250.

[0058] When the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the first standard voltage m1 and less than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=001 at this time, which can be understood as the second stage of power-on or the second last stage of power-off, and the electric quantity of the pixel electrode and the common electrode on the display panel 30 is still relatively large at this time, and needs to be discharged as soon as possible. In this regard, the logic judgment module 150 controls the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 to be opened, and controls the first switch T1 to be disconnected, so that the output ports of the source driving chip 100 are short-circuited together and are short-circuited with the common electrode and grounded.

[0059] When the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=011 at this time, which can be understood as that all the pixel electrodes need to be discharged quickly, but since the voltages of each pixel electrode are different, the logic judgment module 150 needs to control the fourth switch T4 and the fifth switch T5 to be opened, and controls the first switch T1, the second switch T2 and the third switch T3 to be disconnected, so that all the output ports of the source driving chip 100 are short-circuited (i.e. all the pixel electrodes are short-circuited), and then are short-circuited to the ground line, so as to quickly discharge the pixel electrodes.

[0060] When the reference voltage is greater than the power supply voltage, and the power supply voltage is less than the first standard voltage m1, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=100 at this time, which can be understood as the latter half of the abnormal power-off of the power supply voltage (DVDD) or the initial stage of the voltage recovery after the abnormal power-off. In this case, the logic judgment module 150 controls the second switch T2 and the third switch T3 to be open, and controls the first switch T1, the fourth switch T4 and the fifth switch T5 to be disconnected, so as to short all the output ports in the source driving chip 100 and short-circuit with the common electrode, so as to ensure that the pixel electrode voltage and the common electrode voltage are lowered at the same time.

[0061] When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the first standard voltage m1 and less than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=101 at this time, which can be understood as the first half of the abnormal power-off of the power supply voltage (DVDD) or the latter half of the recovery after the abnormal power-off. At this time, the logic judgment module 150 controls the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 to be open, and controls the first switch T1 to be disconnected, so as to short all the output ports in the source driving chip 100, and then short-circuit to the ground line to realize short-circuit, so as to quickly discharge the pixel electrode and the common electrode.

[0062] When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=111 at this time, which can be understood as the display time period of the display panel 30. The logic judgment module 150 controls the first switch T1 to be open, and controls the second switch T2, the third switch T3, the fourth switch T4 and the fifth switch T5 to be disconnected, so that the source driving chip 100 maintains normal voltage output.

[0063] In some embodiments, the display driving circuit 20 can also include more than four comparators. The connection sequence of more comparators is similar to the third embodiment, which will not be described here.

[0064] Fourth embodiment:

[0065] As Figure 8As shown, the display driving circuit provided in the fourth embodiment of the present application is based on the third embodiment, and further comprises a sixth switch T6 in the first shorting module 120. The input end of the sixth switch T6 is connected with the input end of the second switch T2, the output end of the sixth switch T6 is grounded, and the control end of the sixth switch T6 is connected with the output end of the logic judging module 150. The logic judging module 150 controls the opening and closing of the first switch T1, the second switch T2, the third switch T3, the fourth switch T4, the fifth switch T5 and the sixth switch T6 according to the output results of the first comparator 130, the second comparator 140 and the third comparator 170.

[0066] In the third embodiment, when A1:A2:A3=011, the output ports of the source driving chip 100 are shorted to the ground line first, so as to accelerate the discharge of the pixel electrode, and the common electrode can only be discharged slowly. Due to the existence of the first resistor R1, when the DVDD changes from 0.9V to 1.1V or from 1.1V to 0.9V, there is a voltage difference between the pixel electrode and the common electrode, which may cause a short and slight flicker. Based on this, the fourth embodiment of the present application adds the sixth switch T6 in the first shorting module 120, so as to accelerate the discharge of the common electrode and avoid the voltage difference between the pixel electrode and the common electrode.

[0067] A1 A2 A3 Open switch 0 0 0 T2, T3 0 0 1 T2, T3, T4, T5, T6 0 1 1 T4, T5, T6 1 0 0 T2, T3 1 0 1 T2, T3, T4, T5, T6 1 1 1 T1

[0068] Table 2

[0069] In the embodiment of the present application, when the reference voltage is less than the power supply voltage, and the power supply voltage is less than the first standard voltage m1, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=000. At this time, it can be understood as the initial period of power-on or the last period of power-off, and the electric quantity of the pixel electrode and the common electrode on the display panel 30 is relatively small. In this case, the logic judging module 150 controls the second switch T2 and the third switch T3 to be opened, and controls the first switch T1, the fourth switch T4 and the fifth switch T5 to be disconnected, so as to short the output ports of the source driving chip 100 together, and short the output ports with the common electrode, the common electrode signal channel 250 and the common electrode signal line.

[0070] When the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the first standard voltage m1 and less than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=001 at this time, which can be understood as the second stage of power-on or the second last stage of power-off, at which time the pixel electrode and the common electrode on the display panel 30 still have relatively large amounts of electricity, which needs to be discharged as soon as possible. In this regard, the logic judgment module 150 controls the second switch T2, the third switch T3, the fourth switch T4, the fifth switch T5 and the sixth switch T6 to be turned on, while controlling the first switch T1 to be turned off, so as to short the output ports of the source driving chip 100 together, and short-circuit the output ports with the common electrode and ground, and then connect through the first resistor R1, so as to simultaneously accelerate the discharge of the pixel electrode and the common electrode.

[0071] When the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=011 at this time, which can be understood as that the pixel electrode needs to be quickly discharged, but since the voltage of each pixel electrode is different, the fourth switch T4, the fifth switch T5 and the sixth switch T6 need to be controlled by the logic judgment module 150 to be turned on, while the first switch T1, the second switch T2 and the third switch T3 are controlled to be turned off, so as to short all the output ports (i.e. short-circuit all the pixel electrodes) in the source driving chip 100, and then short to the ground line, so as to quickly discharge the pixel electrode.

[0072] When the reference voltage is greater than the power supply voltage, and the power supply voltage is less than the first standard voltage m1, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be represented as A1:A2:A3=100 at this time, which can be understood as the latter half of the abnormal power-off of the power supply voltage (DVDD) or the initial stage of the voltage recovery after the abnormal power-off. In this regard, the logic judgment module 150 controls the second switch T2 and the third switch T3 to be turned on, while controlling the first switch T1, the fourth switch T4 and the fifth switch T5 to be turned off, so as to short all the output ports in the source driving chip 100, and short-circuit the output ports with the common electrode, so as to ensure that the pixel electrode voltage and the common electrode voltage are simultaneously dropped.

[0073] When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the first standard voltage m1 and less than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140 and the third comparator 170 can be expressed as A1:A2:A3 = 101. This can be understood as the first half of the abnormal power outage of the power supply voltage (DVDD) or the second half of the recovery after the abnormal power outage. At this time, the logic determination module 150 controls the second switch T2, the third switch T3, the fourth switch T4, the fifth switch T5 and the sixth switch T6 to open, and at the same time controls the first switch T1 to open, so as to short-circuit all the output ports in the source driver chip 100, then short-circuit them with the common electrode, and then short-circuit them with the ground line, and then connect them through the first resistor R1 to quickly discharge the pixel electrode and the common electrode.

[0074] When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the second standard voltage m2, the output results of the first comparator 130, the second comparator 140, and the third comparator 170 can be expressed as A1:A2:A3 = 111. At this time, the display panel 30 is in the display period. The logic determination module 150 controls the first switch T1 to open, and at the same time controls the second switch T2, the third switch T3, the fourth switch T4, and the fifth switch T5 to open. The source driver chip 100 maintains normal voltage output.

[0075] like Figure 9 As shown, in some embodiments, the gamma chip 200 includes a low-dropout regulator (LDO) 210, a resistor divider module 220, and a fourth comparator 230. The LDO receives a reference voltage (AVDD) and outputs it to the resistor divider module 220. The resistor divider module 220 outputs multiple drive signals. Each drive signal is converted into a gamma voltage and a common voltage by a digital-to-analog converter (DAC) and an amplifier (OP). The gamma voltage (gamma) is output to the source driver chip 100 through a gamma channel 240, and the common voltage (CFVCOM) is output to the source driver chip 100 through a common electrode signal channel 250. The gamma chip 200 is connected to the source driver chip 100 through n gamma channels 240 and one common electrode signal channel 250. The gamma chip 200 includes n digital-to-analog converters and n amplifiers.

[0076] The positive input end of the fourth comparator 230 receives a power supply voltage, the negative input end of the fourth comparator 230 receives a third standard voltage m3, and the output end of the fourth comparator 230 is connected with the receiving end of the logic judgment module 150; wherein the third standard voltage m3 is 70% of the power supply voltage; the gamma chip 200 further comprises n seventh switches T7 and n-1 eighth switches T8, the gamma channel 240 and the common electrode signal channel 250 are connected with the source electrode driving chip 100 through the corresponding seventh switches T7; adjacent two gamma channels 240 are connected through one eighth switch T8, and the common electrode signal channel 250 and adjacent gamma channels 240 are also connected through one eighth switch T8; the control ends of the seventh switches T7 and the eighth switches T8 are connected with the output end of the logic judgment module 150, and the logic judgment module 150 controls the opening and closing of the seventh switches T7 and the eighth switches T8 according to the output result of the fourth comparator 230.

[0077] When the fourth comparator 230 detects that DVDD is lower than 70% of the normal DVDD (i.e. the power supply voltage DVDD drops from 1.8V to 1.2V), all the seventh switches T7 are disconnected, all the eighth switches T8 are opened and short-circuited, and the gamma voltage output by the gamma chip 200 to the source electrode driving chip 100 and the pixel electrode are all output with the same voltage, so that the voltage output by the source electrode driving chip 100 to the pixel electrode of the display panel 30 is consistent with the common voltage, so as to ensure that the pixel electrode voltage is consistent with the common electrode voltage when the power is on and off, thereby avoiding the flicker problem.

[0078] In some embodiments, there is only one logic judgment module 150 in the display driving circuit 20, i.e. the source electrode driving chip 100 and the gamma chip 200 share one logic judgment module 150. Of course, there can be more than two logic judgment modules 150 in the display driving circuit 20, and independent logic judgment modules 150 are respectively used in the source electrode driving chip 100 and the gamma chip 200.

[0079] As shown in Figure 10 The present application further provides a display device, which comprises a display panel 30 and a display driving circuit 20 as described above, wherein the display panel 30 adopts a liquid crystal panel (Liquid Crystal Display, LCD).

[0080] The above is a further detailed description of the present application in combination with specific optional embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, some simple deductions or replacements can be made without departing from the concept of the present application, and all of them shall be regarded as falling within the protection scope of the present application.

Claims

1. A display driving circuit, characterized in that, include: Source driver chip: and A gamma chip, wherein the gamma chip is connected to the source driver chip through multiple gamma channels and a common electrode signal channel; The source driver chip includes: Multiple source signal driving modules, each source signal driving module including a first switch, the input terminal of the first switch being connected to the gamma channel, and the output terminal of the first switch being connected to the data line in the display panel. The first shorting module includes a second switch and multiple third switches. The input terminal of the second switch is connected to the common electrode signal channel, and the output terminal of the second switch is connected to the corresponding source signal driving module through the third switch. The first comparator receives a reference voltage at its positive input terminal and a power supply voltage at its negative input terminal. A second comparator, wherein the positive input of the second comparator receives a power supply voltage, and the negative input of the second comparator receives a first standard voltage; and The logic determination module has its receiving end connected to the output ends of the first comparator and the second comparator, and its output end connected to the control ends of the first switch, the second switch and the third switch. The logic determination module controls the opening and closing of the first switch, the second switch and the third switch according to the output results of the first comparator and the second comparator. The first standard voltage is the voltage of the display panel at the initial stage of power-on or the voltage of the display panel at the final stage of power-off.

2. The display driving circuit as described in claim 1, characterized in that, When the power supply voltage is less than the first standard voltage, the logic determination module controls the second switch and the third switch to open, and controls the first switch to open.

3. The display driving circuit as described in claim 2, characterized in that, The display driving circuit further includes a second shorting module, which includes a fourth switch and a plurality of fifth switches. The input and output terminals of each fifth switch are respectively connected to two adjacent source signal driving modules, and all the fifth switches are grounded through the fourth switch. The output of the logic determination module is also connected to the control terminals of the fourth and fifth switches, and controls the opening and closing of the first, second, third, fourth and fifth switches according to the output results of the first and second comparators.

4. The display driving circuit as described in claim 3, characterized in that, When the power supply voltage is less than the first standard voltage, the logic determination module controls the second switch and the third switch to open and controls the first switch to open; or, when the power supply voltage is less than the first standard voltage, the logic determination module controls the second switch, the third switch, the fourth switch and the fifth switch to open and controls the first switch to open.

5. The display driving circuit as described in claim 3, characterized in that, The display driving circuit further includes a third comparator. The positive input terminal of the third comparator receives the power supply voltage, and the negative input terminal of the third comparator receives a second standard voltage. The second standard voltage is the voltage of the display panel when it is in the power-on secondary stage or the voltage of the display panel when it is in the penultimate power-off stage. The output of the third comparator is connected to the receiving end of the logic determination module. The logic determination module controls the opening and closing of the first switch, the second switch, the third switch, the fourth switch, and the fifth switch based on the output results of the first comparator, the second comparator, and the third comparator.

6. The display driving circuit as described in claim 5, characterized in that, When the reference voltage is less than the power supply voltage, and the power supply voltage is less than the first standard voltage, the logic determination module controls the second switch and the third switch to open, and simultaneously controls the first switch, the fourth switch and the fifth switch to open. When the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic determination module controls the second switch, the third switch, the fourth switch and the fifth switch to open, and at the same time controls the first switch to open; When the reference voltage is less than the power supply voltage and the power supply voltage is greater than the second standard voltage, the logic determination module controls the fourth switch and the fifth switch to open, and simultaneously controls the first switch, the second switch and the third switch to open. When the reference voltage is greater than the power supply voltage and the power supply voltage is less than the first standard voltage, the logic determination module controls the second switch and the third switch to open, and simultaneously controls the first switch, the fourth switch and the fifth switch to open. When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic determination module controls the second switch, the third switch, the fourth switch and the fifth switch to open, and at the same time controls the first switch to open; When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the second standard voltage, the logic determination module controls the first switch to open, and simultaneously controls the second switch, the third switch, the fourth switch, and the fifth switch to open.

7. The display driving circuit as described in claim 5, characterized in that, The first short-circuit module further includes a sixth switch, the input terminal of which is connected to the input terminal of the second switch, the output terminal of which is grounded, and the control terminal of which is connected to the output terminal of the logic determination module. The logic determination module controls the opening and closing of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch according to the output results of the first comparator, the second comparator, and the third comparator. When the reference voltage is less than the power supply voltage, and the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic determination module controls the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch to open, and at the same time controls the first switch to open; When the reference voltage is less than the power supply voltage and the power supply voltage is greater than the second standard voltage, the logic determination module controls the fourth switch, the fifth switch and the sixth switch to open, and at the same time controls the first switch, the second switch and the third switch to open. When the reference voltage is greater than the power supply voltage, and the power supply voltage is greater than the first standard voltage and less than the second standard voltage, the logic determination module controls the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch to open, while controlling the first switch to open.

8. The display driving circuit as described in any one of claims 1-7, characterized in that, The first short-circuit module further includes a first resistor, and the input terminal of the second switch is connected to the common electrode signal channel through the first resistor.

9. The display driving circuit as described in any one of claims 1-8, characterized in that, The gamma chip is connected to the source driver chip through n gamma channels and a common electrode signal channel; The gamma chip includes a fourth comparator, the positive input of which receives a power supply voltage, the negative input of which receives a third standard voltage, and the output of which is connected to the receiving end of the logic determination module; wherein the third standard voltage is 70% of the power supply voltage. The gamma chip also includes n seventh switches and n-1 eighth switches. The gamma channel and the common electrode signal channel are connected to the source driver chip through the corresponding seventh switch. Two adjacent gamma channels are connected through one eighth switch, and the common electrode signal channel and the adjacent gamma channel are also connected through one eighth switch. The control terminals of the seventh and eighth switches are connected to the output terminals of the logic determination module, and the logic determination module controls the opening and closing of the seventh and eighth switches according to the output result of the fourth comparator.

10. A display device, characterized in that, It includes a display panel and a display driving circuit as described in any one of claims 1-9, wherein the display driving circuit is used to drive the display panel.

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