An LCD drive circuit, liquid crystal display and display device for suppressing output fluctuations

Abstract

This invention provides an LCD driving circuit, a liquid crystal display screen, and a display device for suppressing output fluctuations. The LCD driving circuit includes a power input module, a Schmitt trigger device, and an XON module. The power input module is connected to the Vin voltage input terminal of the Schmitt trigger device; the Vout voltage output terminal of the Schmitt trigger device is connected to the input terminal of the XON module. When the power input module is on, the Schmitt trigger device outputs a high level, and the XON module also outputs a high level, enabling the display panel to operate normally. When the power input module is off, the Schmitt trigger device outputs a low level, and the XON module also outputs a low level, allowing the display panel to release residual charge. The Schmitt trigger device is unaffected by minor fluctuations in the input voltage, maintaining stable high and low level outputs. This avoids output signal fluctuations caused by the XON module's susceptibility to minor power voltage fluctuations, suppressing output fluctuations in the driving circuit, preventing abnormal images, and enhancing display effects and user experience.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display technology, and in particular to an LCD driving circuit, a liquid crystal display screen, and a display device for suppressing output fluctuations. Background Technology

[0002] Liquid Crystal Displays (LCDs) have numerous advantages, including thinness, energy efficiency, and no radiation, leading to their widespread use. LCDs require a driving circuit to control their display content, and this circuit typically consists of a large number of digital logic gates. Digital logic gates are one of the most basic building blocks of digital integrated circuits, usually containing several transistors and capacitors. Although components of the same type undergo the same manufacturing process, uncertainties in various factors during manufacturing result in differences between them. These differences mainly manifest in the electrical parameters of the components, such as resistance, capacitance, and inductance. Therefore, components manufactured from the same design drawings will have different actual electrical parameters—this is known as process technology variation. Process technology variation significantly impacts the performance of digital logic gates, often causing output signal jitter and noise. These problems severely affect the display quality of LCDs, leading to blurry images, ghosting, and other defects. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing an LCD driving circuit, liquid crystal display screen, and display device that suppresses output fluctuations, thereby reducing output fluctuations caused by differences in component manufacturing processes and improving display performance and user experience.

[0004] To achieve the above objectives, in a first aspect, embodiments of the present invention provide an LCD driving circuit for suppressing output fluctuations, comprising: a power input module, a Schmitt trigger device, and an XON module;

[0005] The power input module is connected to the Vin voltage input terminal of the Schmitt trigger device;

[0006] The Vout voltage output terminal of the Schmitt trigger is connected to the input terminal of the XON module;

[0007] When the power input module is turned on, the Schmitt trigger device outputs a high level, and the XON module also outputs a high level, enabling the display panel to work normally.

[0008] After the power input module is turned off, the Schmitt trigger outputs a low level, and the XON module also outputs a low level, causing the display panel to release residual charge.

[0009] The Schmitt trigger device includes a voltage divider circuit, a first transistor, and a second transistor. Both the first transistor and the second transistor are NPN transistors. The voltage divider circuit is used to provide the base voltage (b-point) of the second transistor.

[0010] Furthermore, the Schmitt trigger device also includes resistors R3 and R6;

[0011] One end of resistor R3 is connected to the emitter point e of the first transistor, and the other end of resistor R3 is grounded.

[0012] One end of resistor R6 is connected to the DC power supply VAA, and the other end of resistor R6 is connected to the collector point c of the second transistor.

[0013] Furthermore, the voltage divider circuit includes resistors R2, R4, and R5 connected in sequence;

[0014] The collector c of the first transistor is connected between resistor R2 and resistor R4;

[0015] The base b point of the first transistor is connected to the power input module after being connected to resistor R1.

[0016] The emitter points of both the first and second transistors are connected to ground via resistor R3.

[0017] The base point b of the second transistor is connected between resistors R4 and R5;

[0018] Resistor R1 is also connected to DC power supply VAA, and resistor R5 is grounded.

[0019] Preferably, the XON module includes a current limiting protection circuit and a third transistor;

[0020] The output terminal of the Schmitt trigger is connected to the current limiting protection circuit of the XON module, so that the output voltage of the Schmitt trigger is limited by the current limiting protection circuit and outputs a limiting voltage, which is then input to the base point b of the third transistor.

[0021] Furthermore, the current limiting protection circuit includes resistors R7, R8, and R9;

[0022] One end of resistor R7 is connected to the output terminal of the Schmitt trigger device, and the other end of resistor R7 is connected to the base point b of the third transistor.

[0023] One end of resistor R8 is connected to the base point b of the third transistor, and the other end of resistor R8 is grounded.

[0024] One end of resistor R9 is connected to the emitter point e of the third transistor, and the other end of resistor R9 is grounded.

[0025] Furthermore, the XON output terminal is drawn between the emitter e point of the third transistor and the resistor R9.

[0026] Preferably, the collector c point of the third transistor is connected to a DC voltage VDD.

[0027] Secondly, embodiments of the present invention also provide a liquid crystal display screen, including an LCD driving circuit as provided in any embodiment of the present invention, wherein the LCD driving circuit is disposed in a non-display area of ​​the liquid crystal display screen.

[0028] Thirdly, embodiments of the present invention also provide a display device, including a housing and a liquid crystal display screen as provided in any embodiment of the present invention, wherein the liquid crystal display screen is assembled inside the housing.

[0029] Compared with the prior art, the advantages and positive effects of the present invention are that by adding a Schmitt trigger device to the LCD driving circuit, it is less affected by small fluctuations in the input voltage and can maintain a stable high-level and low-level output, that is, it keeps the input voltage of the XON module stable, thereby avoiding the output signal fluctuation caused by the XON module being easily affected by small power supply voltage fluctuations, suppressing the output fluctuation of the driving circuit, avoiding screen abnormalities, and enhancing the display effect and user experience. Attached Figure Description

[0030] Figure 1 A schematic diagram of an LCD driving circuit for suppressing output fluctuations is provided in one embodiment of the present invention;

[0031] Figure 2 A circuit diagram of an LCD driving circuit for suppressing output fluctuations is provided in one embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of a liquid crystal display screen according to an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of a display device provided in one embodiment of the present invention. Detailed Implementation

[0034] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0035] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0036] To address the problems of the prior art, one embodiment of the present invention provides an LCD driving circuit for suppressing output fluctuations, see reference. Figure 1-2 The LCD driving circuit for suppressing output fluctuations includes: a power input module 1, a Schmitt trigger device 2, and an XON module 3; the power input module 1 is connected to the Vin input terminal of the Schmitt trigger device 2; the Vout output terminal of the Schmitt trigger device 2 is connected to the input terminal of the XON module 3; when the power input module 1 is turned on, the Schmitt trigger device 2 outputs a high level, and the XON module 3 also outputs a high level, enabling the display panel to work normally; when the power input module 1 is turned off, the Schmitt trigger device 2 outputs a low level, and the XON module 3 also outputs a low level, enabling the display panel to release residual charge.

[0037] In LCD driving circuits, the XON module typically includes a transistor that outputs different signals depending on the input voltage. Its specific function is as follows: when the XON module's output signal is pulled low, all the GOUT output voltages of the Gate IC are pulled to the VGH level, turning on the TFTs and releasing residual charge in the display panel to prevent image retention during shutdown. However, due to differences in transistor programming, the actual transistor voltage drop in the XON module often differs from the preset voltage drop. This can easily cause even small input voltage fluctuations to cause the transistor to switch from the on state to the off state, resulting in accidental charge release during normal display panel operation. This severely affects the display effect of the LCD panel, leading to image blurring, image retention, and other defects.

[0038] Therefore, the embodiments of the present invention employ the above-described technical solution to address the deficiencies of the prior art. Because the Schmitt trigger device possesses a certain hysteresis, small power supply voltage fluctuations will not affect the level output of the Schmitt trigger device. The output signal only changes when the input voltage changes sufficiently, and its output signal has only one stable high level and one low level. Therefore, as the input signal of the XON module, its output signal will only change due to the electrical change in the input signal when the input voltage changes sufficiently (considered as the power supply being off, resulting in a significant voltage attenuation). Thus, the embodiments of the present invention, through the above-described technical solution, eliminate noise and jitter, ensure the stability of the output signal of the LCD driving circuit, effectively suppress output fluctuations caused by differences in transistor manufacturing processes, solve problems caused by process differences, and improve the stability and reliability of the circuit.

[0039] Preferably, in embodiments of the present invention, such as Figure 1-2As shown, the power input module 1 includes a VCC input terminal. When the power input module 1 is turned on, the VCC input terminal preferably receives a 12V voltage. In this embodiment, when the voltage at the Vin input terminal of the Schmitt trigger device 2 is greater than 8.5V, the Vout output terminal of the Schmitt trigger device 2 will output a high level. This high level causes the XON module 3 to also output a high level, ensuring the display panel operates normally and displays a stable image. When the power input module 1 is turned off, the input voltage at the VCC input terminal begins to decrease. When the Vin voltage at the Schmitt trigger device 2 is lower than 8.5V, the Vout output terminal voltage of the Schmitt trigger device 2 will be 0V, resulting in a 0V input voltage for the XON module. At this time, the XON module 3 will also output a low level, correctly pulling the signal low and releasing residual charge on the display panel.

[0040] Furthermore, such as Figure 2 As shown, the Schmitt trigger device includes: a voltage divider circuit, a first transistor, and a second transistor. Both the first transistor and the second transistor are NPN transistors. The voltage divider circuit is used to provide the base voltage (b-point) of the second transistor.

[0041] Furthermore, such as Figure 2 As shown, the Schmitt trigger device further includes resistors R3 and R6; resistors R3 and R6 mainly serve to set the circuit voltage. One end of resistor R3 is connected to the emitter (e) of the first transistor BJT1, and the other end of resistor R3 is grounded; one end of resistor R6 is connected to the DC power supply VAA, and the other end of resistor R6 is connected to the collector (c) of the second transistor BJT2. Resistors R3 and R6 function as voltage dividers and protect the circuit.

[0042] Further, the voltage divider circuit includes resistors R2, R4, and R5 connected in sequence; the collector point c of the first transistor BJT1 is connected between resistors R2 and R4; the base point b of the first transistor BJT1 is connected to the power input module after being connected to resistor R1; the emitter points e of both the first transistor BJT1 and the second transistor BJT2 are connected to ground after being connected to resistor R3; the base point b of the second transistor BJT2 is connected between resistors R4 and R5; resistor R1 is also connected to the DC power supply VAA, and resistor R5 is grounded.

[0043] Preferably, the XON module includes a current limiting protection circuit and a third transistor BJT3; the output terminal Vout of the Schmitt trigger device is connected to the current limiting protection circuit of the XON module, so that the output voltage of the output terminal of the Schmitt trigger device is limited by the current limiting protection circuit and outputs a limiting voltage, which is input to the base b point of the third transistor BJT3.

[0044] Furthermore, the current limiting protection circuit includes resistors R7, R8, and R9; one end of resistor R7 is connected to the output terminal of the Schmitt trigger device, and the other end of resistor R7 is connected to the base point b of the third transistor BJT3; one end of resistor R8 is connected to the base point b of the third transistor BJT3, and the other end of resistor R8 is grounded; one end of resistor R9 is connected to the emitter point e of the third transistor BJT3, and the other end of resistor R9 is grounded.

[0045] Furthermore, an XON output terminal is drawn between the emitter e point of the third transistor BJT3 and the resistor R9.

[0046] Furthermore, the collector c point of the third transistor BJT3 is connected to a DC voltage VDD, preferably providing a voltage input of 1.8V.

[0047] In this embodiment of the invention, the VCC input terminal preferably receives a 12V voltage, and the DC power supply VAA preferably receives a 17.65V voltage. The emitter (e) voltage of the first transistor BJT1 needs to be set to 7.5V through a voltage divider circuit according to the resistor voltage divider principle. When the input power is turned on, the base (b) of the first transistor BJT1 in the Schmitt trigger device (i.e., the Vin input terminal) is greater than 8.5V, and its b-point voltage is greater than the e-point voltage. Therefore, the first transistor BJT1 will conduct, outputting a 17.65V voltage from c to e, ultimately grounded. Simultaneously, because the base (b) of the second transistor BJT2 has no voltage, the second transistor BJT2 is in a turned-off state. The Schmitt trigger device will output a 17.65V voltage, which enters the base (b) of the third transistor BJT3 in the XON module. This voltage turns on the third transistor BJT3, and XON will output a high level, allowing the display panel to function normally. When the input power is turned off, the voltage at the VCC terminal begins to decay. When it decays sufficiently, the voltage at the Vin terminal of the Schmitt trigger will be lower than 8.5V. At this point, the first transistor BJT1 will be off, and the VAA output voltage will flow to the base (b) of the second transistor BJT2, causing the second transistor BJT2 to conduct. The VAA voltage will then flow through the c point to the e point of the second transistor BJT2, eventually grounding. The output of the Schmitt trigger will be 0V. Therefore, the third transistor BJT3 will be off, causing the XON module to output a low level, correctly releasing the residual charge in the display panel.

[0048] The above solution effectively avoids excessive output fluctuations caused by the transistor process, maintaining a high level of 17.65V and a low level of 0V at the output terminal, suppressing output fluctuations in the LCD driver circuit, ensuring stable output signals of the driver circuit, thereby improving circuit stability and reliability, and enhancing display effects and user experience.

[0049] Secondly, embodiments of the present invention also provide a liquid crystal display screen, see reference. Figure 3 The liquid crystal display screen 10 provided in the embodiments of the present invention includes an LCD driving circuit 20 for suppressing output fluctuations provided in any embodiment of the present invention, and the LCD driving circuit 20 is disposed in the non-display area of ​​the liquid crystal display screen.

[0050] The liquid crystal display screen also includes a display area 2, in which a liquid crystal display panel is disposed for displaying images.

[0051] The liquid crystal display screen provided by the embodiments of the present invention can output high or low levels correctly without being affected by minor voltage fluctuations in the input power supply, effectively suppressing fluctuating output and improving display effect and user experience.

[0052] Thirdly, embodiments of the present invention also provide a display device, please refer to... Figure 4 The display device 100 provided in this embodiment of the invention includes a housing 110 and a liquid crystal display screen 120 provided in any embodiment of the invention. The liquid crystal display screen 120 is assembled inside the housing 110. The display device in this embodiment of the invention includes, but is not limited to, electronic devices such as liquid crystal displays, liquid crystal televisions, and mobile phones. The display device provided in this embodiment of the invention can correctly output high or low levels without being affected by small voltage fluctuations in the input power supply, effectively suppressing fluctuating output and improving display effect and user experience.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An LCD driving circuit for suppressing output fluctuations, characterized in that, include: Power input module, Schmitt trigger and XON module; The power input module is connected to the Vin voltage input terminal of the Schmitt trigger device; The Vout voltage output terminal of the Schmitt trigger device is connected to the input terminal of the XON module. The Schmitt trigger device includes a voltage divider circuit, a first transistor, and a second transistor. Both the first transistor and the second transistor are NPN transistors. The voltage divider circuit provides the base voltage (b-point) of the second transistor. The XON module includes a current limiting protection circuit and a third transistor. The output terminal of the Schmitt trigger device is connected to the current limiting protection circuit of the XON module, so that the output voltage of the Schmitt trigger device is limited by the current limiting protection circuit and outputs a limiting voltage. The limiting voltage is input to the base voltage (b-point) of the third transistor. When the power input module is turned on, the Schmitt trigger device outputs a high level, and the XON module also outputs a high level, so that the display panel works normally. After the power input module is turned off, the Schmitt trigger device outputs a low level, and the XON module also outputs a low level, causing the display panel to release residual charge.

2. The LCD driving circuit for suppressing output fluctuations according to claim 1, characterized in that, The Schmitt trigger device also includes resistors R3 and R6; One end of the resistor R3 is connected to the emitter e of the first transistor, and the other end of the resistor R3 is grounded. One end of the resistor R6 is connected to the DC power supply VAA, and the other end of the resistor R6 is connected to the collector point c of the second transistor.

3. The LCD driving circuit for suppressing output fluctuations according to claim 1, characterized in that, The voltage divider circuit includes resistors R2, R4, and R5 connected in sequence; The collector c of the first transistor is connected between resistor R2 and resistor R4; The base b point of the first transistor is connected to the power input module via a resistor R1. The emitter e-points of both the first transistor and the second transistor are connected to ground after being connected to the resistor R3; The base point b of the second transistor is connected between resistor R4 and resistor R5; The resistor R1 is also connected to the DC power supply VAA, and the resistor R5 is grounded.

4. The LCD driving circuit for suppressing output fluctuations according to claim 1, characterized in that, The current limiting protection circuit includes resistors R7, R8, and R9; One end of the resistor R7 is connected to the output terminal of the Schmitt trigger device, and the other end of the resistor R7 is connected to the base point b of the third transistor. One end of the resistor R8 is connected to the base point b of the third transistor, and the other end of the resistor R8 is grounded. One end of the resistor R9 is connected to the emitter e point of the third transistor, and the other end of the resistor R9 is grounded.

5. The LCD driving circuit for suppressing output fluctuations according to claim 4, characterized in that, An XON output terminal is drawn between the emitter e point of the third transistor and the resistor R9.

6. The LCD driving circuit for suppressing output fluctuations according to claim 3, characterized in that, The collector c of the third transistor is connected to a DC voltage VDD.

7. A liquid crystal display screen, characterized in that, The LCD driving circuit includes the output fluctuation suppression method as described in any one of claims 1-6, wherein the LCD driving circuit is disposed in the non-display area of ​​the liquid crystal display screen.

8. A display device, characterized in that, It includes a housing and a liquid crystal display screen as described in claim 7, wherein the liquid crystal display screen is assembled within the housing.

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