WO2017185422A1 - 一种过流保护电路及液晶显示器 - Google Patents

一种过流保护电路及液晶显示器 Download PDF

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Publication number
WO2017185422A1
WO2017185422A1 PCT/CN2016/082189 CN2016082189W WO2017185422A1 WO 2017185422 A1 WO2017185422 A1 WO 2017185422A1 CN 2016082189 W CN2016082189 W CN 2016082189W WO 2017185422 A1 WO2017185422 A1 WO 2017185422A1
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Prior art keywords
voltage
effect transistor
field effect
detection
current
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Ceased
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PCT/CN2016/082189
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English (en)
French (fr)
Inventor
张先明
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TCL China Star Optoelectronics Technology Co Ltd
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Shenzhen China Star Optoelectronics Technology Co Ltd
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Priority to US15/100,418 priority Critical patent/US10116131B2/en
Publication of WO2017185422A1 publication Critical patent/WO2017185422A1/zh
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/006—Calibration or setting of parameters
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1345—Conductors connecting electrodes to cell terminals
    • G02F1/13454—Drivers integrated on the active matrix substrate
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/136—Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • G02F1/1362—Active matrix addressed cells
    • G02F1/136204—Arrangements to prevent high voltage or static electricity failures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/093—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current with timing means

Definitions

  • the present invention relates to the field of liquid crystal display technology, and in particular, to an overcurrent protection circuit and a liquid crystal display.
  • the GateDriver On Array (GOA) technology is a technology for fabricating a gate scan driving circuit of a thin film transistor (TFT) on an array substrate instead of an external silicon chip. Since the GOA circuit can be directly fabricated around the panel, the thickness of the frame of the liquid crystal display (LCD) panel can be reduced, the process process can be simplified, the product cost can be reduced, and the integration degree of the liquid crystal panel can be improved.
  • TFT thin film transistor
  • the gate voltage of each row of TFTs in the liquid crystal display can be provided by a GOA circuit.
  • a level shifter LevelShifter
  • OCP OverCurrent Protection
  • the short-circuit point occurs in a low-impedance short-circuit, the current will be large, and OCP over-current protection can easily be triggered at this time.
  • the current value is not too large.
  • the current value will become larger and larger until the panel is melted. Therefore, it is difficult to set an accurate protection point when setting the OCP protection current. If the protection point is set too large, the short-circuited screen may be missed and the screen may be directly melted.
  • Another object of the present invention is to provide a liquid crystal display using the above-described overcurrent protection circuit.
  • An overcurrent protection circuit wherein the overcurrent protection circuit includes a detection circuit, a first protection branch, and a second protection branch, wherein the detection circuit is configured to detect an output of the overcurrent protection circuit in real time. a current of the terminal, and obtaining a first detection voltage according to a current of the output end of the overcurrent protection circuit, the first protection branch comparing the first detection voltage with a first reference voltage, when the first When the detection voltage is less than the first reference voltage, the second protection branch obtains a reference detection voltage according to the first detection voltage during the first operation, when the first detection voltage is smaller than the first When the voltage is referenced, the detecting circuit detects the current of the output end of the overcurrent protection circuit in real time, and obtains a second detection voltage according to the current of the output end of the overcurrent protection circuit, and the second protection branch will The second detection voltage is compared with the second reference voltage.
  • the second protection branch cuts off the current of the input end of the overcurrent protection circuit. Input, where The second reference voltage equal to the reference detection voltage plus a predetermined initial value, wherein the predetermined initial value is positive.
  • the first protection branch includes a first voltage comparator and a first field effect transistor, and the non-inverting input terminal of the first voltage comparator receives the first detection voltage, and the first voltage comparator Receiving, by the inverting input terminal, the first reference voltage, an output end of the first voltage comparator is electrically connected to a gate of the first field effect transistor, and a source of the first transistor is electrically connected to the overcurrent protection An input of the circuit, the drain of the first field effect transistor is grounded, and the first voltage comparator is configured to compare the first detection voltage with the first reference voltage, when the first detection The first field effect transistor is turned off when the voltage is less than the first reference voltage.
  • the first field effect transistor is an NMOS.
  • the first voltage comparator When the first detection voltage is less than the first reference voltage, the first voltage comparator generates a low level, and the low level passes the The first output terminal outputs, and the first field effect transistor is turned off according to a low level output by the first output terminal.
  • the second protection branch includes a second voltage comparator and a second field effect transistor, and the non-inverting input of the second voltage comparator receives the second detection voltage, and the second voltage comparator An inverting input terminal receives the second reference voltage, an output of the second voltage comparator is electrically connected to a gate of the second field effect transistor, and a source of the second field effect transistor is electrically connected to the An input of the flow protection circuit, a drain of the second field effect transistor is grounded, and the second comparator is used to The second detection voltage is compared with the second reference voltage, and when the second detection voltage is greater than or equal to the second reference voltage, the second field effect transistor is turned on.
  • the second field effect transistor is an NMOS.
  • the second detection voltage is greater than or equal to the second reference voltage
  • the second voltage comparator generates a high level, and the high level passes through the The second output terminal outputs, and the second field effect transistor is turned on according to a high level outputted by the second output terminal.
  • the second protection branch further includes an adder, the adder includes a first input end, a second input end, and an output end, and the first input end receives the reference detection voltage, The second input terminal receives the preset initial value, and the adder is configured to add the reference detection voltage to the preset initial value to obtain the second reference voltage, where the second reference voltage is The output of the adder is output.
  • the first protection branch cuts off a current input of an input end of the overcurrent protection circuit.
  • the detecting circuit includes a current detecting circuit and a current-voltage converter.
  • the current detecting circuit detects a current signal at an output end of the overcurrent protection circuit, and amplifies the current signal to obtain an effective current signal.
  • the current-to-voltage converter receives the effective current signal and converts the effective current signal into a corresponding voltage signal.
  • the current detecting circuit includes a third field effect transistor and a fourth field effect transistor, and a gate of the third field effect transistor is electrically connected to a gate of the fourth field effect transistor, the third field effect a source of the transistor is electrically connected to a source of the fourth field effect transistor, and a drain of the third field effect transistor is used as an input end of the current detecting circuit to detect a current of an output end of the overcurrent protection circuit a signal, a drain of the fourth thin film transistor serving as an output of the current detecting circuit to output the effective current signal.
  • a liquid crystal display comprising an overcurrent protection circuit, the overcurrent protection circuit comprising a detection circuit, a first protection branch and a second protection branch, wherein the detection circuit is configured to detect the overcurrent protection circuit in real time a current of the output terminal, and obtaining a first detection voltage according to a current of the output end of the overcurrent protection circuit, the first protection branch comparing the first detection voltage with a first reference voltage, when When the first detection voltage is less than the first reference voltage, the second protection branch obtains a reference detection voltage according to the first detection voltage during the first operation, when the first detection voltage is less than the The first detecting voltage, the detecting circuit detects the current of the output end of the overcurrent protection circuit in real time, and according to the overcurrent The current at the output of the protection circuit obtains a second detection voltage, and the second protection branch compares the second detection voltage with a second reference voltage, when the second detection voltage is greater than or equal to the first When the voltage is referenced, the second protection branch cuts off the current input of the input end of the overcurrent protection
  • the first protection branch includes a first voltage comparator and a first field effect transistor, and the non-inverting input terminal of the first voltage comparator receives the first detection voltage, and the first voltage comparator Receiving, by the inverting input terminal, the first reference voltage, an output end of the first voltage comparator is electrically connected to a gate of the first field effect transistor, and a source of the first transistor is electrically connected to the overcurrent protection An input of the circuit, the drain of the first field effect transistor is grounded, and the first voltage comparator is configured to compare the first detection voltage with the first reference voltage, when the first detection The first field effect transistor is turned off when the voltage is less than the first reference voltage.
  • the first field effect transistor is an NMOS.
  • the first voltage comparator When the first detection voltage is less than the first reference voltage, the first voltage comparator generates a low level, and the low level passes the The first output terminal outputs, and the first field effect transistor is turned off according to a low level output by the first output terminal.
  • the second protection branch includes a second voltage comparator and a second field effect transistor, and the non-inverting input of the second voltage comparator receives the second detection voltage, and the second voltage comparator An inverting input terminal receives the second reference voltage, an output of the second voltage comparator is electrically connected to a gate of the second field effect transistor, and a source of the second field effect transistor is electrically connected to the An input of the current protection circuit, a drain of the second field effect transistor is grounded, and the second comparator is configured to compare the second detection voltage with the second reference voltage when the second detection When the measured voltage is greater than or equal to the second reference voltage, the second field effect transistor is turned on.
  • the second field effect transistor is an NMOS.
  • the second detection voltage is greater than or equal to the second reference voltage
  • the second voltage comparator generates a high level, and the high level passes through the The second output terminal outputs, and the second field effect transistor is turned on according to a high level outputted by the second output terminal.
  • the second protection branch further includes an adder, the adder includes a first input end, a second input end, and an output end, and the first input end receives the reference detection voltage,
  • the second input terminal receives the preset initial value, and the adder is configured to add the reference detection voltage
  • the preset initial value is used to obtain the second reference voltage, and the second reference voltage is output via an output of the adder.
  • the first protection branch cuts off a current input of an input end of the overcurrent protection circuit.
  • the detecting circuit includes a current detecting circuit and a current-voltage converter.
  • the current detecting circuit detects a current signal at an output end of the overcurrent protection circuit, and amplifies the current signal to obtain an effective current signal.
  • the current-to-voltage converter receives the effective current signal and converts the effective current signal into a corresponding voltage signal.
  • the current detecting circuit includes a third field effect transistor and a fourth field effect transistor, and a gate of the third field effect transistor is electrically connected to a gate of the fourth field effect transistor, the third field effect a source of the transistor is electrically connected to a source of the fourth field effect transistor, and a drain of the third field effect transistor is used as an input end of the current detecting circuit to detect a current of an output end of the overcurrent protection circuit a signal, a drain of the fourth thin film transistor serving as an output of the current detecting circuit to output the effective current signal.
  • the current detecting circuit detects the current signals of the respective GOA lines and converts them into the first detecting voltage first protection branch, and when the voltage comparator determines that the effective voltage signal is smaller than the first detecting voltage is less than
  • the second protection branch obtains a reference detection voltage according to the first detection voltage in the first operation, and the second protection branch uses the second detection voltage and the second detection voltage
  • the reference voltage is compared, and when the second detection voltage is greater than or equal to the second reference voltage, the second protection branch cuts off a current input of an input end of the overcurrent protection circuit.
  • the overcurrent protection circuit of the present invention can correct the protection voltage value to further prevent overcurrent.
  • the liquid crystal display of the present invention is capable of correcting the protection voltage value and further preventing the overcurrent phenomenon.
  • FIG. 1 is a schematic diagram of a circuit of an overcurrent protection circuit of the present invention.
  • FIG. 2 is a circuit diagram showing another embodiment of the overcurrent protection circuit of the present invention.
  • FIG. 1 is a schematic diagram of an overcurrent protection circuit according to an embodiment of the present invention.
  • the overcurrent protection circuit described in this embodiment includes a detection circuit 20, a first protection branch 30, and a second protection branch 40.
  • the detecting circuit 20 is configured to detect a current of an output end of the overcurrent protection circuit in real time, and obtain a first detection voltage according to a current of an output end of the overcurrent protection circuit.
  • the detecting circuit 20 specifically includes a current detecting circuit 21 and a current voltage converter 22.
  • the first protection branch 30 is configured to compare the first detection voltage with a first reference voltage.
  • the first protection branch 30 specifically includes a first voltage comparator 31 and a first field effect transistor 32.
  • the second protection branch is configured to compare the second detection voltage with a second reference voltage, and when the second detection voltage is greater than or equal to the second reference voltage, the second protection branch The circuit cuts off the current input at the input of the overcurrent protection circuit.
  • the second protection branch 40 includes a second voltage comparator 41 and a second field effect transistor 42.
  • An input end 211 of the current detecting circuit 21 is connected to an output end of the overcurrent protection circuit, and an output terminal 210 of the current detecting circuit 21 is connected to the current voltage converter 22, and the current voltage converter 22 is connected to the
  • the non-inverting input terminal of the first voltage comparator 31 is connected to the first reference voltage Vr1, and the first voltage comparator is compared with the non-inverting input terminal of the first voltage comparator 31 and the non-inverting input terminal of the second voltage comparator 42.
  • the output of the device 31 is coupled to the gate of the first field effect transistor 32.
  • An output of the second voltage comparator 41 is coupled to a gate of the second field effect transistor 42.
  • the output end of the overcurrent protection circuit can be connected to a GOA circuit, and the input end of the overcurrent protection circuit can be connected to a timing control circuit.
  • the input terminal 211 of the current detecting circuit 21 respectively detects the current signal of each stage of the GOA circuit and amplifies it into an effective current signal and outputs it to the current-voltage converter 22 (the current-voltage converter 22 converts the detected current signal into The voltage signal, for example, converts the detected 1 mA current signal A voltage signal of 10 mV, wherein the larger the detected current signal is, the larger the converted voltage signal is, the current-to-voltage converter 22 converts the effective current signal into an in-phase of the effective voltage signal output to the first voltage comparator 31.
  • the input and the non-inverting input of the second voltage comparator 42 The input and the non-inverting input of the second voltage comparator 42.
  • the voltage comparator can compare the magnitudes of the two input voltages and output a high level or a low level according to the comparison result, specifically, when the voltage of the non-inverting input terminal ("+" input terminal) is higher than the inverting input terminal ( When the voltage of the "one" input terminal is high, the voltage comparator outputs a high level; when the voltage of the "+” input terminal is lower than the voltage of the "one” input terminal, the voltage comparator outputs a low level.
  • the logic switch circuit 70 includes a first field effect transistor that is turned on when the gate of the field effect transistor receives a high level and turns off when the gate receives a low level.
  • the current detecting circuit 21 detects the current of the output end of the overcurrent protection circuit in real time, and converts the current detecting voltage to obtain a first detecting voltage.
  • the first protection branch 30 passes through the first voltage comparator 31. And comparing the first detection voltage with the first reference voltage Vr1, when the first detection voltage is less than the first reference voltage Vr1, the entire overcurrent protection current works normally, and the second The protection branch 40 obtains the reference detection voltage according to the first detection voltage at the first (normal) operation to obtain the reference detection voltage. That is to say, the reference detection voltage value at this time is equal to the first detection voltage value.
  • the detecting circuit detects the current of the output end of the overcurrent protection circuit in real time under the condition that the first detection voltage is less than the first reference voltage, and obtains the current according to the current of the output end of the overcurrent protection circuit.
  • the second detection branch 40 compares the second detection voltage with a second reference voltage, and when the second detection voltage is greater than or equal to the second reference voltage, The second protection branch cuts off the current input of the input end of the overcurrent protection circuit, wherein the second reference voltage is equal to the reference detection voltage plus a preset initial value, wherein the preset initial value is positive number.
  • the second protection branch 40 further includes an adder 43 including a first input terminal, a second input terminal, and an output terminal.
  • the first input end and the second input end are interchangeable.
  • the first input terminal is connected to the current-voltage converter 22, the second input terminal is connected to the preset initial value Vr2, and the output terminal is connected to the inverting input terminal of the second voltage comparator 42.
  • the reference detection voltage is processed by the adder 43 to obtain a second reference voltage, and the reference detection voltage is greater than the reference detection voltage.
  • the preset initial value Vr2 it can be preset in the circuit according to requirements.
  • the first voltage comparator 31 determines that the first detection voltage signal is smaller than the first reference voltage Vr1 preset by the first voltage comparator 31.
  • the first voltage comparator 31 outputs a low level to the first field effect transistor 32, and the first field effect transistor 32 remains turned on according to the low level, so that the whole The circuit outputs current to the outside. At this time, the circuit works normally.
  • the adder 43 processes the first detection voltage (that is, the normal operating voltage) to output a second reference voltage, and the second comparator 42 receives the first phase. Two reference voltages.
  • the second comparator 42 outputs a low level to the second field effect transistor 42, the second field effect transistor 42 is turned off, and the entire circuit stops outputting current to provide overcurrent protection.
  • the first voltage comparator 31 determines that the first detection voltage is greater than or equal to the first reference voltage Vr1 during operation, the first voltage comparator 31 is to the first field effect.
  • the transistor 32 outputs a high level, and the first field effect transistor 32 also acts as an overcurrent protection according to the high level open circuit.
  • the circuit works normally, and the effective voltage is processed by the adder 43 (the second reference voltage is set to 20V), and the output is added.
  • the voltage is 43V to the inverting input of the second voltage comparator 42. If the subsequent GOA circuit is short-circuited, so that the effective voltage is increased to 70V, at this time, although the first voltage comparator 31 outputs a low level, the second voltage comparator 42 outputs a high level, so the logic switch circuit 70 is triggered to be turned off.
  • the power supply acts as a protection circuit.
  • the overcurrent protection circuit of the present invention can correct the protection voltage value, and can effectively prevent circuit damage caused by the protection voltage setting being too high.
  • the first reference voltage Vr1 is set to 80V
  • the first detection voltage is 70V
  • the circuit works normally, and the first detection voltage is processed by the adder 43 (preset initial value Vr2) Set to 20V)
  • the second reference voltage is outputted to 70V to the inverting input of the second voltage comparator 42. If the subsequent GOA circuit is short-circuited, so that the second detection voltage is increased to 85V, the first voltage comparator 31 outputs a high level. Although the second voltage comparator 42 outputs a low level, the overcurrent protection circuit is still Disconnected, so the present invention does not increase the protection voltage.
  • the first reference voltage Vr1 is set to 100V
  • the first detection voltage is 110V
  • the first voltage comparator 31 outputs a high level, and the first field effect transistor 32 is triggered, the entire circuit It is disconnected to protect the circuit.
  • the second voltage comparator 42 has no current flowing in.
  • the current-voltage converter 22 converts the current into a voltage corresponding thereto.
  • the current-voltage converter 22 stores a correspondence table between the current and the voltage in advance. In the correspondence table between the current and the voltage, the larger the current, the larger the voltage.
  • the current detecting circuit 21 includes a third FET Q1 and a fourth FET Q2, wherein: the drain of the third FET Q1 is connected to the GOA circuit, and the third FET a source of Q1 and a source of the fourth field effect transistor Q2 are connected to a gate driving voltage, and a gate of the third field effect transistor Q1 is connected to a gate of the fourth field effect transistor Q2.
  • a drain of the third field effect transistor Q1 is used as an input end of the current detecting circuit to detect a current signal at an output end of the overcurrent protection circuit, and a drain of the fourth field effect transistor Q2 is connected to a current voltage converter twenty two.
  • the current detecting circuit 21 amplifies the detected current signal into an effective current signal, and transmits the current signal to the current-voltage converter 22.
  • the third field effect transistor Q1 and the fourth field effect transistor Q2 are both NMOS transistors.
  • the current-voltage converter 22 can control the magnitude of the current to be converted into a voltage by the magnitude of the resistor R.
  • the first end of the resistor R is connected to the drain of the fourth field effect transistor Q2, the non-inverting input end of the first voltage comparator 31 and the second voltage comparator 42, and the resistor R The two ends are grounded.
  • 43 I ⁇ R
  • I is the current input from the current-voltage converter 22
  • 43 is the voltage output from the current-voltage converter 22.
  • the greater the resistance of the resistor R the stronger the conversion capability of the current-to-voltage converter 22 to convert the current into a voltage.
  • the magnitude of the resistor R in the embodiment of the present invention can be set according to the reference voltage of the first voltage comparator 31.
  • Embodiments of the present invention also provide a liquid crystal display including the overcurrent protection circuit shown in FIG. 1. Please refer to the description of the overcurrent protection circuit shown in FIG. 1 above, and details are not described herein again.

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  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Protection Of Static Devices (AREA)

Abstract

一种过流保护电路包括侦测电路（20）、第一保护支路（30）及第二保护支路（40），该侦测电路（20）用于得到第一侦测电压，第一保护支路（30）将第一侦测电压与第一参考电压进行比较，当第一侦测电压小于第一参考电压时，侦测电路（20）得到第二侦测电压，第二保护支路（40）将第二侦测电压与第二参考电压进行比较，当第二侦测电压大于或等于第二参考电压时，第二保护支路（40）切断过流保护电路的输入端的电流输入，第二参考电压等于基准侦测电压加上预设初始值。该过流保护电路可以修正保护电压值，进一步防止过流现象。一种液晶显示器具有该过流保护电路，能够修正保护电压值，进一步防止过流现象。

Description

一种过流保护电路及液晶显示器
本发明要求2016年4月27日递交的发明名称为“一种过流保护电路及液晶显示器”的申请号201610269787.0的在先申请优先权，上述在先申请的内容以引入的方式并入本文本中。
技术领域
本发明涉及液晶显示技术领域，具体涉及一种过流保护电路及液晶显示器。
背景技术
阵列基板行驱动(GateDriverOnArray，GOA)技术，是一种将薄膜晶体管(ThinFilmTransistor，TFT)的栅极扫描驱动电路制作在阵列基板上，以替代外接硅芯片制作的驱动芯片的一种技术。由于GOA电路可直接制作在面板周围，可以降低液晶显示器(LiquidCrystalDisplay，LCD)的面板的边框厚度，简化制程工艺，而且降低产品成本，提高液晶面板的集成度。
液晶显示器中的每一行TFT的栅极电压可以通过GOA电路提供，在GOA电路中，一般使用电平转换器(LevelShifter)产生时钟控制信号控制每一行TFT开启或关闭。在液晶显示器的制造过程中，如果液晶显示器的框胶密封不严，容易造成面板内的GOA电路之间出现短路，会产生大电流信号，此时会启动过流保护(OverCurrentProtection，OCP)电路以关闭电平转换器，从而防止液晶显示面板被烧坏。若短路点发生在低阻抗短路，电流会很大，这个时候会很容易触发OCP过流保护。但是很多时候会发生短路后会在短路点有阻抗，电流值并不是太大，随着时间的递增，电流值会越来越大，直至将面板融掉。因此，在设定OCP保护电流时就很难设定准确的保护点，若设置保护点过大，可能会漏掉短路的屏，使屏直接融掉。
发明内容
本发明的目的在于提供一种过流保护电路，该电路可以修正过流保护电压，以更好地保护电路。
本发明的另一目的在于提供一种采用上述过流保护电路的液晶显示器。
为了实现上述目的，本发明实施方式提供如下技术方案：
一种过流保护电路，其中，所述过流保护电路包括侦测电路、第一保护支路及第二保护支路，所述侦测电路用于实时侦测所述过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第一侦测电压，所述第一保护支路将所述第一侦测电压与第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第二保护支路根据第一次工作时的第一侦测电压得到基准侦测电压，当所述第一侦测电压小于所述第一参考电压时，所述侦测电路实时侦测过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第二侦测电压，所述第二保护支路将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入，其中，所述第二参考电压等于所述基准侦测电压加上预设初始值，其中，所述预设初始值为正数。
其中，所述第一保护支路包括第一电压比较器及第一场效应晶体管，所述第一电压比较器的同相输入端接收所述第一侦测电压，所述第一电压比较器的反相输入端接收所述第一参考电压，所述第一电压比较器的输出端电连接所述第一场效应晶体管的栅极，所述第一晶体管的源极电连接所述过流保护电路的输入端，所述第一场效应晶体管的漏极接地，所述第一电压比较器用于将所述第一侦测电压与所述第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第一场效应晶体管断开。
其中，所述第一场效应晶体管为NMOS，当所述第一侦测电压小于所述第一参考电压时，所述第一电压比较器产生低电平，且所述低电平通过所述第一输出端输出，所述第一场效应晶体管根据所述第一输出端输出的低电平断开。
其中，所述第二保护支路包括第二电压比较器及第二场效应晶体管，所述第二电压比较器的同相输入端接收所述第二侦测电压，所述第二电压比较器的反相输入端接收所述第二参考电压，所述第二电压比较器的输出端电连接所述第二场效应晶体管的栅极，所述第二场效应晶体管的源极电连接所述过流保护电路的输入端，所述第二场效应晶体管的漏极接地，所述第二比较器用于将所 述第二侦测电压与所述第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二场效应晶体管导通。
其中，所述第二场效应晶体管为NMOS，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二电压比较器产生高电平，所述高电平通过所述第二输出端输出，所述第二场效应晶体管根据所述第二输出端输出的高电平导通。
其中，所述第二保护支路还包括加法运算器，所述加法运算器包括第一输入端、第二输入端及输出端，所述第一输入端接收所述基准侦测电压，所述第二输入端接收所述预设初始值，所述加法运算器用于将所述基准侦测电压加上所述预设初始值以得到所述第二参考电压，所述第二参考电压经由所述加法运算器的输出端输出。
其中，当所述第一侦测电压大于或等于所述第一参考电压时，所述第一保护支路切断所述过流保护电路的输入端的电流输入。
其中，所述侦测电路包括电流侦测电路和电流电压转换器，所述电流侦测电路侦测所述过流保护电路的输出端的电流信号，并将电流信号放大以得到有效电流信号，所述电流电压转换器接收所述有效电流信号，并将所述有效电流信号转换为对应的电压信号。
其中，所述电流侦测电路包括第三场效应晶体管及第四场效应晶体管，所述第三场效应晶体管的栅极电连接所述第四场效应晶体管的栅极，所述第三场效应晶体管的源极电连接所述第四场效应晶体管的源极，所述第三场效应晶体管的漏极作为所述电流侦测电路的输入端，侦测所述过流保护电路的输出端的电流信号，所述第四薄膜晶体管的漏极作为所述电流侦测电路的输出端以输出所述有效电流信号。
一种液晶显示器，包括过流保护电路，所述过流保护电路包括侦测电路、第一保护支路及第二保护支路，所述侦测电路用于实时侦测所述过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第一侦测电压，所述第一保护支路将所述第一侦测电压与第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第二保护支路根据第一次工作时的第一侦测电压得到基准侦测电压，当所述第一侦测电压小于所述第一参考电压时，所述侦测电路实时侦测过流保护电路的输出端的电流，并根据所述过流 保护电路的输出端的电流得到第二侦测电压，所述第二保护支路将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入，其中，所述第二参考电压等于所述基准侦测电压加上预设初始值，其中，所述预设初始值为正数。
其中，所述第一保护支路包括第一电压比较器及第一场效应晶体管，所述第一电压比较器的同相输入端接收所述第一侦测电压，所述第一电压比较器的反相输入端接收所述第一参考电压，所述第一电压比较器的输出端电连接所述第一场效应晶体管的栅极，所述第一晶体管的源极电连接所述过流保护电路的输入端，所述第一场效应晶体管的漏极接地，所述第一电压比较器用于将所述第一侦测电压与所述第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第一场效应晶体管断开。
其中，所述第一场效应晶体管为NMOS，当所述第一侦测电压小于所述第一参考电压时，所述第一电压比较器产生低电平，且所述低电平通过所述第一输出端输出，所述第一场效应晶体管根据所述第一输出端输出的低电平断开。
其中，所述第二保护支路包括第二电压比较器及第二场效应晶体管，所述第二电压比较器的同相输入端接收所述第二侦测电压，所述第二电压比较器的反相输入端接收所述第二参考电压，所述第二电压比较器的输出端电连接所述第二场效应晶体管的栅极，所述第二场效应晶体管的源极电连接所述过流保护电路的输入端，所述第二场效应晶体管的漏极接地，所述第二比较器用于将所述第二侦测电压与所述第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二场效应晶体管导通。
其中，所述第二场效应晶体管为NMOS，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二电压比较器产生高电平，所述高电平通过所述第二输出端输出，所述第二场效应晶体管根据所述第二输出端输出的高电平导通。
其中，所述第二保护支路还包括加法运算器，所述加法运算器包括第一输入端、第二输入端及输出端，所述第一输入端接收所述基准侦测电压，所述第二输入端接收所述预设初始值，所述加法运算器用于将所述基准侦测电压加上 所述预设初始值以得到所述第二参考电压，所述第二参考电压经由所述加法运算器的输出端输出。
其中，当所述第一侦测电压大于或等于所述第一参考电压时，所述第一保护支路切断所述过流保护电路的输入端的电流输入。
其中，所述侦测电路包括电流侦测电路和电流电压转换器，所述电流侦测电路侦测所述过流保护电路的输出端的电流信号，并将电流信号放大以得到有效电流信号，所述电流电压转换器接收所述有效电流信号，并将所述有效电流信号转换为对应的电压信号。
其中，所述电流侦测电路包括第三场效应晶体管及第四场效应晶体管，所述第三场效应晶体管的栅极电连接所述第四场效应晶体管的栅极，所述第三场效应晶体管的源极电连接所述第四场效应晶体管的源极，所述第三场效应晶体管的漏极作为所述电流侦测电路的输入端，侦测所述过流保护电路的输出端的电流信号，所述第四薄膜晶体管的漏极作为所述电流侦测电路的输出端以输出所述有效电流信号。
本发明实施例具有如下优点或有益效果：
本发明实施例中，电流侦测电路分别侦测各条GOA线路的电流信号并转换为第一侦测电压第一保护支路，当电压比较器判断有效电压信号小于第一侦测电压小于所述第一参考电压时，所述第二保护支路根据第一次工作时的第一侦测电压得到基准侦测电压，所述第二保护支路将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入。通过本发明的过流保护电路可以修正保护电压值，进一步防止过流现象。本发明的液晶显示器能够修正保护电压值，进一步防止过流现象。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明过流保护电路电路示意图。
图2是本发明过流保护电路另一种实施例电路示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
请参阅图1，图1是本发明实施例公开的一种过流保护电路的示意图。如图1所示，本实施例中所描述的过流保护电路，包括侦测电路20、第一保护支路30和第二保护支路40。所述侦测电路20用于实时侦测所述过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第一侦测电压。所述侦测电路20具体包括电流侦测电路21和电流电压转换器22。所述第一保护支路30用于将所述第一侦测电压与第一参考电压进行比较。所述第一保护支路30具体包括第一电压比较器31和第一场效应管32。所述第二保护支路用于将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入。所述第二保护支路40包括第二电压比较器41和第二场效应管42。
所述电流侦测电路21输入端211连接所述过流保护电路的输出端，所述电流侦测电路21输出端210连接所述电流电压转换器22，所述电流电压转换器22连接所述第一电压比较器31同相输入端和所述第二电压比较器42的同相输入端，所述第一电压比较器31的反相输入端接入第一参考电压Vr1，所述第一电压比较器31的输出端连接所述第一场效应晶体管32的栅极。所述第二电压比较器41的输出端连接所述第二场效应晶体管42的栅极。
可以理解的是，所述过流保护电路的输出端可以接一GOA电路，所述过流保护电路的输入端可以接一时序控制电路。
电流侦测电路21的输入端211分别侦测每级GOA电路的电流信号并将其放大为有效电流信号输出至电流电压转换器22(电流电压转换器22用于将检测到的电流信号转换为电压信号，例如，将检测到的1mA的电流信号转换 为10mV的电压信号，其中，检测到的电流信号越大，被转换成的电压信号越大)，电流电压转换器22将有效电流信号转换为有效电压信号输出至第一电压比较器31的同相输入端和第二电压比较器42的同相输入端。
电压比较器可对两个输入电压的大小进行比较，并根据比较结果输出高电平或低电平，具体为，当同相输入端(“+”输入端)的电压高于反相输入端(“一”输入端)的电压时，电压比较器输出高电平；当“+”输入端的电压低于“一”输入端的电压时，电压比较器输出低电平。所述逻辑开关电路70包括第一场效应管，当场效应管的栅极接收高电平时导通，栅极接收低电平时截止。
电流侦测电路21实时侦测所述过流保护电路的输出端的电流，并通过电流电压转换器22转换后得到第一侦测电压，所述第一保护支路30通过第一电压比较器31并将所述第一侦测电压与第一参考电压Vr1进行比较，当所述第一侦测电压小于所述第一参考电压Vr1时，整个过流保护电流正常工作，此时所述第二保护支路40根据第一次(正常)工作时的第一侦测电压得到基准侦测电压得到基准侦测电压。也就是说，此时的基准侦测电压值就等于第一侦测电压值。在所述第一侦测电压小于所述第一参考电压的条件下，所述侦测电路实时侦测过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第二侦测电压，所述第二保护支路40将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入，其中，所述第二参考电压等于所述基准侦测电压加上预设初始值，其中，所述预设初始值为正数。
进一步的，所述第二保护支路40还包括加法运算器43，所述加法运算器43包括第一输入端、第二输入端和输出端。所述第一输入端和所述第二输入端之间可以互换。第一输入端接所述电流电压转换器22，第二输入端接预设初始值Vr2，输出端接所述第二电压比较器42反相输入端。所述基准侦测电压经所述加法运算器43处理后得到第二参考电压，所述基准侦测电压大于所述基准侦测电压。对于预设初始值Vr2可以在电路中根据需求预设。
当第一电压比较器31判断第一侦测电压信号小于第一电压比较器31预设的第一参考电压Vr1时。所述第一电压比较器31向所述第一场效应晶体管32输出低电平，所述第一场效应晶体管32根据所述低电平保持接通，使得整个 电路向外输出电流。此时电路正常工作，所述加法运算器43将所述第一侦测电压(也就是正常工作电压)处理后输出第二参考电压，所述第二比较器42反相输入端接收所述第二参考电压。后续如果工作电压超过第二参考电压，则第二比较器42向第二场效应晶体管42输出低电平，第二场效应晶体管42断开，整个电路停止输出电流，起到过流保护作用。当然，若工作过程中，所述第一电压比较器31判断所述第一侦测电压大于或等于所述第一参考电压Vr1时，所述第一电压比较器31向所述第一场效应晶体管32输出高电平，所述第一场效应晶体管32根据所述高电平断开电路，同样起到过流保护作用。
在一个具体的实施例中，若第一参考电压Vr1设置为100V，若有效电压为40V，则电路正常工作，有效电压经加法运算器43处理后(第二参考电压设置为20V)，输出加法电压为43V到第二电压比较器42的反相输入端。若后续GOA电路短路，使得有效电压增大到70V，此时虽然第一电压比较器31输出低电平，但第二电压比较器42输出高电平，因此逻辑开关电路70被触发，断开电源，起到保护电路的作用。本发明的过流保护电路可以修正保护电压值，能够有效防止保护电压设置过高造成的电路损毁。
在一个具体的实施例中，若第一参考电压Vr1设置为80V，若第一侦测电压为70V，则电路正常工作，第一侦测电压经加法运算器43处理后(预设初始值Vr2设置为20V)，输出第二参考电压为70V到第二电压比较器42的反相输入端。若后续GOA电路短路，使得第二侦测电压增大到85V，此时第一电压比较器31输出高电平，虽然此时第二电压比较器42输出低电平，过流保护电路依然被断开，因此本发明不会提高保护电压。
在另外一个具体实施例中，若第一参考电压Vr1设置为100V，若第一侦测电压为110V，则第一电压比较器31输出高电平，第一场效应晶体管32被触发，整个电路被断开，起到保护电路的作用。此时，第二电压比较器42没有电流流入。
由于GOA电路的电流往往比较小，因此需要将其放大后进行侦测，电流电压转换器22接收到电流侦测电路21输出的电流之后，将该电流转换为与之对应的电压。较佳地，所述电流电压转换器22中预先存储有电流与电压之间的对应关系表，在电流与电压之间的对应关系表中，电流越大，电压越大。进 一步优选的，所述电流侦测电路21包括第三场效应管Q1和第四场效应管Q2，其中：所述第三场效应管Q1的漏极连接GOA电路，所述第三场效应管Q1的源极与所述第四场效应管Q2的源极均连接栅极驱动电压，所述第三场效应管Q1的栅极与所述第四场效应管Q2的栅极相连，所述第三场效应管Q1的漏极作为所述电流侦测电路的输入端，侦测所述过流保护电路的输出端的电流信号，所述第四场效应管Q2的漏极连接电流电压转换器22。所述电流侦测电路21将侦测的电流信号放大为有效电流信号，并将该电流信号传输给电流电压转换器22。
优选的，所述第三场效应管Q1和第四场效应管Q2均为NMOS管。
优选的，本发明实施例中，电流电压转换器22可以通过电阻R的大小控制电流转换为电压的大小。具体的，所述电阻R的第一端连接所述第四场效应管Q2的漏极、所述第一电压比较器31和第二电压比较器42的同相输入端，所述电阻R的第二端接地。其中，43＝I×R，I为电流电压转换器22输入的电流，43为电流电压转换器22输出的电压。所述电阻R的阻值越大，则电流电压转换器22将电流转换为电压的转换能力越强，本发明实施例中的电阻R的大小可以根据第一电压比较器31的参考电压进行设定，在电流侦测电路21的电流放大倍数一定的情况下，所述第一电压比较器31的参考电压越大，设置R越大。实施本发明实施例，可以通过设置R的大小，灵活调整电流电压转换器22的转换能力。
可以理解的是，请参阅图2。还可以将第二电压比较器42的输出端接在所述第一场效应晶体管32的栅极从而省去第二场效应管42。当然，还可以将第一电压比较器32的输出端接在所述第二场效应晶体管42的栅极从而省去第一场效应管32。
本发明实施例还提供一种包括图1所示的过流保护电路的液晶显示器。请参看上述对图1所示的过流保护电路的描述，在此不再赘述。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不一定指的是相同的实施例或示例。而且，描述的具 体特征、结构、材料或特点可以在任何的一个或多个实施例或示例中以合适的方式结合。
以上所述的实施方式，并不构成对该技术方案保护范围的限定。任何在上述实施方式的精神和原则之内所作的修改、等同替换和改进等，均应包含在该技术方案的保护范围之内。

Claims (18)

  1. 一种过流保护电路，其中，所述过流保护电路包括侦测电路、第一保护支路及第二保护支路，所述侦测电路用于实时侦测所述过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第一侦测电压，所述第一保护支路将所述第一侦测电压与第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第二保护支路根据第一次工作时的第一侦测电压得到基准侦测电压，当所述第一侦测电压小于所述第一参考电压时，所述侦测电路实时侦测过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第二侦测电压，所述第二保护支路将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入，其中，所述第二参考电压等于所述基准侦测电压加上预设初始值，其中，所述预设初始值为正数。
  2. 如权利要求1所述的过流保护电路，其中，所述第一保护支路包括第一电压比较器及第一场效应晶体管，所述第一电压比较器的同相输入端接收所述第一侦测电压，所述第一电压比较器的反相输入端接收所述第一参考电压，所述第一电压比较器的输出端电连接所述第一场效应晶体管的栅极，所述第一晶体管的源极电连接所述过流保护电路的输入端，所述第一场效应晶体管的漏极接地，所述第一电压比较器用于将所述第一侦测电压与所述第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第一场效应晶体管断开。
  3. 如权利要求2所述的过流保护电路，其中，所述第一场效应晶体管为NMOS，当所述第一侦测电压小于所述第一参考电压时，所述第一电压比较器产生低电平，且所述低电平通过所述第一输出端输出，所述第一场效应晶体管根据所述第一输出端输出的低电平断开。
  4. 如权利要求1所述的过流保护电路，其中，所述第二保护支路包括第二电压比较器及第二场效应晶体管，所述第二电压比较器的同相输入端接收所述第二侦测电压，所述第二电压比较器的反相输入端接收所述第二参考电压，所述第二电压比较器的输出端电连接所述第二场效应晶体管的栅极，所述第二场效应晶体管的源极电连接所述过流保护电路的输入端，所述第二场效应晶体管的漏极接地，所述第二比较器用于将所述第二侦测电压与所述第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二场效应晶体管导通。
  5. 如权利要求4所述的过流保护电路，其中，所述第二场效应晶体管为NMOS，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二电压比较器产生高电平，所述高电平通过所述第二输出端输出，所述第二场效应晶体管根据所述第二输出端输出的高电平导通。
  6. 如权利要求4所述的过流保护电路，其中，所述第二保护支路还包括加法运算器，所述加法运算器包括第一输入端、第二输入端及输出端，所述第一输入端接收所述基准侦测电压，所述第二输入端接收所述预设初始值，所述加法运算器用于将所述基准侦测电压加上所述预设初始值以得到所述第二参考电压，所述第二参考电压经由所述加法运算器的输出端输出。
  7. 如权利要求1所述的过流保护电路，其中，当所述第一侦测电压大于或等于所述第一参考电压时，所述第一保护支路切断所述过流保护电路的输入端的电流输入。
  8. 如权利要求1所述的过流保护电路，其中，所述侦测电路包括电流侦测电路和电流电压转换器，所述电流侦测电路侦测所述过流保护电路的输出端的电流信号，并将电流信号放大以得到有效电流信号，所述电流电压转换器接收所述有效电流信号，并将所述有效电流信号转换为对应的电压信号。
  9. 如权利要求8所述的过流保护电路，其中，所述电流侦测电路包括第三 场效应晶体管及第四场效应晶体管，所述第三场效应晶体管的栅极电连接所述第四场效应晶体管的栅极，所述第三场效应晶体管的源极电连接所述第四场效应晶体管的源极，所述第三场效应晶体管的漏极作为所述电流侦测电路的输入端，侦测所述过流保护电路的输出端的电流信号，所述第四薄膜晶体管的漏极作为所述电流侦测电路的输出端以输出所述有效电流信号。
  10. 一种液晶显示器，包括过流保护电路，所述过流保护电路包括侦测电路、第一保护支路及第二保护支路，所述侦测电路用于实时侦测所述过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第一侦测电压，所述第一保护支路将所述第一侦测电压与第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第二保护支路根据第一次工作时的第一侦测电压得到基准侦测电压，当所述第一侦测电压小于所述第一参考电压时，所述侦测电路实时侦测过流保护电路的输出端的电流，并根据所述过流保护电路的输出端的电流得到第二侦测电压，所述第二保护支路将所述第二侦测电压与第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二保护支路切断所述过流保护电路的输入端的电流输入，其中，所述第二参考电压等于所述基准侦测电压加上预设初始值，其中，所述预设初始值为正数。
  11. 如权利要求10所述的液晶显示器，其中，所述第一保护支路包括第一电压比较器及第一场效应晶体管，所述第一电压比较器的同相输入端接收所述第一侦测电压，所述第一电压比较器的反相输入端接收所述第一参考电压，所述第一电压比较器的输出端电连接所述第一场效应晶体管的栅极，所述第一晶体管的源极电连接所述过流保护电路的输入端，所述第一场效应晶体管的漏极接地，所述第一电压比较器用于将所述第一侦测电压与所述第一参考电压进行比较，当所述第一侦测电压小于所述第一参考电压时，所述第一场效应晶体管断开。
  12. 如权利要求11所述的液晶显示器，其中，所述第一场效应晶体管为NMOS，当所述第一侦测电压小于所述第一参考电压时，所述第一电压比较器 产生低电平，且所述低电平通过所述第一输出端输出，所述第一场效应晶体管根据所述第一输出端输出的低电平断开。
  13. 如权利要求10所述的液晶显示器，其中，所述第二保护支路包括第二电压比较器及第二场效应晶体管，所述第二电压比较器的同相输入端接收所述第二侦测电压，所述第二电压比较器的反相输入端接收所述第二参考电压，所述第二电压比较器的输出端电连接所述第二场效应晶体管的栅极，所述第二场效应晶体管的源极电连接所述过流保护电路的输入端，所述第二场效应晶体管的漏极接地，所述第二比较器用于将所述第二侦测电压与所述第二参考电压进行比较，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二场效应晶体管导通。
  14. 如权利要求13所述的液晶显示器，其中，所述第二场效应晶体管为NMOS，当所述第二侦测电压大于或等于所述第二参考电压时，所述第二电压比较器产生高电平，所述高电平通过所述第二输出端输出，所述第二场效应晶体管根据所述第二输出端输出的高电平导通。
  15. 如权利要求13所述的液晶显示器，其中，所述第二保护支路还包括加法运算器，所述加法运算器包括第一输入端、第二输入端及输出端，所述第一输入端接收所述基准侦测电压，所述第二输入端接收所述预设初始值，所述加法运算器用于将所述基准侦测电压加上所述预设初始值以得到所述第二参考电压，所述第二参考电压经由所述加法运算器的输出端输出。
  16. 如权利要求10所述的液晶显示器，其中，当所述第一侦测电压大于或等于所述第一参考电压时，所述第一保护支路切断所述过流保护电路的输入端的电流输入。
  17. 如权利要求10所述的液晶显示器，其中，所述侦测电路包括电流侦测电路和电流电压转换器，所述电流侦测电路侦测所述过流保护电路的输出端的电流信号，并将电流信号放大以得到有效电流信号，所述电流电压转换器接 收所述有效电流信号，并将所述有效电流信号转换为对应的电压信号。
  18. 如权利要求17所述的液晶显示器，其中，所述电流侦测电路包括第三场效应晶体管及第四场效应晶体管，所述第三场效应晶体管的栅极电连接所述第四场效应晶体管的栅极，所述第三场效应晶体管的源极电连接所述第四场效应晶体管的源极，所述第三场效应晶体管的漏极作为所述电流侦测电路的输入端，侦测所述过流保护电路的输出端的电流信号，所述第四薄膜晶体管的漏极作为所述电流侦测电路的输出端以输出所述有效电流信号。
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