OLED display screen input abnormity power-down protection circuit

Abstract

The utility model provides an OLED display screen input abnormity power-down protection circuit, which relates to the technical field of OLED display screen protection circuits and comprises an input sampling unit, an AC detection unit and an OLED power supply control unit. The input sampling unit is used for carrying out rectification processing on an input power supply signal and outputting a detection signal to the AC detection unit. And the AC detection unit compares the detection signal with a preset reference voltage signal, and outputs a low-level signal when the detection signal is lower than the lowest action voltage signal. And the OLED power supply control unit cuts off the power supply of the OLED display screen according to the low-level signal so as to protect the display screen from being damaged. The protection circuit provided by the utility model can timely respond to the abnormal or power failure condition of the power supply signal, and ensures the safety and stability of the OLED display screen by cutting off the power supply, thereby prolonging the service life of the display screen, and providing more reliable and safer display experience for users.

Description

Technical Field

[0001] The utility model relates to the technical field of OLED display screen protection circuits, in particular to an OLED display screen input abnormal power-off protection circuit. Background Art

[0002] As a next-generation display technology, OLED (organic light-emitting diode) displays have established themselves as a key player in a variety of fields, including smartphones, tablets, televisions, and wearable devices, thanks to their superior display performance and broad application prospects. The operating principle of OLED displays relies on a sophisticated power distribution and control system. The power supply system (PM) is responsible for providing stable operating DC voltage to the system control and function unit (M1), the TCON control unit (M2), and the OLED driver unit (M3). The OLED driver unit (M3), in particular, as the core component that directly drives the OLED display unit, requires a low-voltage, high-current DC voltage from the power supply system to ensure precise control of individual pixel light emission, enabling high-quality image display and backlight brightness adjustment. However, the stability and reliability of the power supply system pose a major challenge in the practical application of OLED displays. OLED displays have extremely high power supply requirements, and any power supply fluctuations or failures caused by external factors can impact the display, even causing permanent damage. Especially in AC power supply environments, the constant fluctuations in voltage and current increase the risk of power supply instability. Furthermore, traditional OLED display solutions have significant shortcomings in power management. When the power input VIN suddenly loses power, if the system control and function unit M1 and the TCON control unit M2 lose power before the OLED driver unit M3, the OLED driver unit will be falsely triggered, causing overcurrent in the OLED display unit. This overcurrent not only causes visual issues such as screen flickering and image sticking, but also accelerates the aging process of the OLED display over a long period of time, and even causes serious failures such as screen burn-in.

[0003] Therefore, there is an urgent need for an OLED display screen power-off protection circuit that can monitor the power supply status in real time and quickly cut off the power supply to the OLED screen when a power supply anomaly is detected, thereby protecting the screen from damage. At the same time, the solution must ensure that the OLED driver unit can respond quickly and accurately during a power outage to avoid false triggering and overcurrent, thereby extending the service life of the OLED screen and improving its stability. Utility Model Content

[0004] The purpose of the utility model is to provide an OLED display screen input abnormal power-off protection circuit to solve the problems of low power supply stability and reliability in the prior art, and easy false triggering and overcurrent during power failure.

[0005] The utility model solves the above problems through the following technical solutions:

[0006] An OLED display screen input abnormal power-off protection circuit includes: an input sampling unit, an AC detection unit and an OLED power supply control unit.

[0007] The input sampling unit is used to rectify the input power supply signal and output a detection signal to the AC detection unit;

[0008] The AC detection unit compares the detection signal with a preset reference voltage signal to determine whether the detection signal is lower than a minimum operating voltage signal, and outputs a corresponding level signal to the OLED power supply control unit, wherein the minimum operating voltage signal is determined according to a preset ratio calculation formula;

[0009] When the detection signal is lower than the lowest action voltage signal of the input terminal, a low level signal is output to control the OLED power supply control unit to cut off the power supply of the voltage output terminal.

[0010] Furthermore, the input sampling unit includes: a diode D1, a diode D2, a resistor R1 and a resistor R2;

[0011] After the resistor R1 and the resistor R2 are connected in series, one end is connected to the detection signal, and the other end is connected to the cathode of the diode D1 and the cathode of the diode D2. The anodes of the diode D1 and the diode D2 are connected to the power supply signal.

[0012] Furthermore, the AC detection unit includes: an operational amplifier, an isolation photoelectric coupler, resistors R4, R5, R6, R7 and R8, and a MOS tube Q1;

[0013] A first end of the capacitor C2 and a first pin of the operational amplifier are connected to a power supply voltage and to a first end of the resistor R3 , and a second end of the capacitor C2 and a second pin of the operational amplifier are grounded;

[0014] The second end of the resistor R3 is connected to the first end of the resistor R4 and the LED anode of the isolation photoelectric coupler, and the second end of the resistor R4 is connected to the LED cathode of the isolation photoelectric coupler and the drain of the MOS tube Q1;

[0015] A first end of the resistor R6 is connected to a first end of the resistor R5 and a detection signal, a second end of the resistor R6 is connected to a first end of the capacitor C1 and a non-inverting input terminal of the operational amplifier, and a second end of the resistor R5 and a second end of the capacitor C1 are grounded;

[0016] A first end of resistor R7 is connected to the preset reference voltage signal, a second end of resistor R7 is connected to the inverting input end of the operational amplifier, an output end of the operational amplifier is connected to a first end of resistor R8, a second end of resistor R8 is connected to a first end of resistor R9 and a first end of capacitor C3 and to the gate of MOS transistor Q1, and a second end of resistor R9, a second end of capacitor C3, and a source of MOS transistor Q1 are grounded.

[0017] Furthermore, the detection unit further includes: a voltage stabilizing diode Z1, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor RF24, a resistor R14, a resistor R15, a capacitor C4, a capacitor C5, a capacitor C6, a MOS transistor Q2, a MOS transistor Q3 and a MOS transistor Q4;

[0018] A first end of the resistor R10 is connected to a first operating voltage, a second end of the resistor R10 is connected to the gate of the MOS transistor Q2, the first end of the capacitor C4, the first end of the resistor R11, the cathode of the voltage-stabilizing diode Z1, and the collector of the photodetector in the isolation photoelectric coupler, a drain of the MOS transistor Q3 is connected to the level signal terminal, the second end of the resistor R12, and the drain of the MOS transistor Q2, a first end of the resistor R12 is connected to a second operating voltage, and an emitter of the photodetector in the isolation photoelectric coupler, an anode of the voltage-stabilizing diode Z1, the second end of the resistor R11, the second end of the capacitor C4, and the source of the MOS transistor Q2 are grounded;

[0019] A first end of the resistor RF24 is connected to the first operating voltage, a second end of the resistor RF24 is connected to the drain of the MOS transistor Q4, the first end of the resistor R13, the first end of the capacitor C5, and the gate of the MOS transistor Q3, and a source of the MOS transistor Q3, a source of the MOS transistor Q4, the second end of the resistor R13, and the second end of the capacitor C5 are grounded;

[0020] The first end of the resistor R15 is connected to the input control signal, the second end of the resistor R15 is connected to the gate of the MOS transistor Q4, the first end of the resistor R14 and the first end of the capacitor C6, and the second end of the resistor R14 and the second end of the capacitor C6 are grounded.

[0021] Furthermore, the OLED power supply control unit includes: resistor R16, resistor R17, resistor R18, resistor R19, resistor R20, resistor R21, resistor R22, resistor RS3, resistor RS4, capacitor C7, capacitor C8, capacitor C9, capacitor C10, voltage regulator diode Z2, MOS transistor Q5 and MOS transistor Q6;

[0022] The first end of the resistor R18, the first end of the capacitor C8, the first end of the capacitor C10, the cathode of the voltage stabilizing diode Z2, the source of the MOS transistor Q5, and the source of the MOS transistor Q6 are connected to the first operating voltage. The second end of the capacitor C10 is connected to the first end of the capacitor C9, the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, and the positive terminal of the control signal output.

[0023] The second end of capacitor C8 is connected to the gate of MOS transistor Q5, the gate of MOS transistor Q6, the anode of Zener diode Z2, the second end of capacitor C9, and the first end of resistor R19. The second end of resistor R18 and the second end of resistor R19 are connected to the drain of MOS transistor Q6. The first end of resistor R16 is connected to the level signal terminal. The second end of resistor R16 is connected to the first end of resistor R17, the first end of capacitor C7, and the gate of MOS transistor Q7. Resistors RS3 and RS4 are connected in parallel with one end connected to the second end of resistor R17, the second end of capacitor C7, the source of MOS transistor Q7, and the negative terminal of the control signal output. The other end is grounded.

[0024] After the resistor R20, the resistor R21 and the resistor R22 are connected in parallel, one end is connected to the voltage output positive end, and the other end is connected to the voltage output negative end. The voltage output positive end and the voltage output negative end constitute the voltage output end.

[0025] Furthermore, it also includes: a power supply system, which converts the power supply signal into an operating voltage signal to output to the OLED power supply control unit; wherein the power supply signal includes an AC power signal and a DC power signal.

[0026] Principle of the utility model: When the power input is normal and the input control signal receives a high-level power-on signal from the system, the electronic switch composed of MOS transistors Q5 and MOS transistors Q6 is in a straight-through state, and the OLED display operates normally. When the power supply signal is lost, the detection signal is at a low level, the operational amplifier outputs a low-level signal, MOS transistor Q1 is cut off, MOS transistor Q2 inputs a high level, the level signal terminal is at a low level, MOS transistor Q7 inputs a low level and is cut off, the electronic switch composed of MOS transistors Q5 and MOS transistors Q6 is cut off, the voltage output terminal has no output, and the power supply to the OLED display is cut off.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) The present invention realizes real-time monitoring and abnormality processing of the power supply signal by designing an input sampling unit, an AC detection unit, and an OLED power supply control unit. When an abnormal power failure of the power supply signal is detected, the power supply to the OLED display screen can be quickly cut off, effectively avoiding damage to the display screen caused by unstable power supply and improving the stability and reliability of the power supply.

[0029] (2) The input sampling unit of the present invention rectifies the power supply signal and outputs a detection signal to the AC detection unit. The AC detection unit can accurately determine whether the power supply signal is lower than the minimum operating voltage signal by comparing the detection signal with a preset reference voltage signal. Once an abnormality is detected, a low-level signal is immediately output to the OLED power supply control unit, achieving a rapid response and cutting off the power supply, effectively protecting the OLED display and extending the service life of the display. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the utility model principle of the utility model;

[0031] Figure 2 This is a schematic diagram of the protection circuit of the utility model;

[0032] Figure 3 This is a schematic diagram of the structure of the OLED display screen of the present utility model. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution, and advantages of the present invention more clear, the technical solution of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them, and the implementation methods of the present invention are not limited to these. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] In the following description, the terms "first\second\third" and similar terms are only used to distinguish similar objects and do not represent a specific order for the objects. It is understandable that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein are for the purpose of describing the embodiments of the present application only and are not intended to limit this application.

[0035] Example 1:

[0036] Combined with attachment Figure 1 As shown, an OLED display screen input abnormal power-off protection circuit includes: an input sampling unit, an AC detection unit and an OLED power supply control unit.

[0037] The input sampling unit is used to rectify the input power supply signal and output a detection signal to the AC detection unit;

[0038] The AC detection unit compares the detection signal with a preset reference voltage signal to determine whether the detection signal is lower than a minimum operating voltage signal, and outputs a corresponding level signal to the OLED power supply control unit, wherein the minimum operating voltage signal is determined according to a preset ratio calculation formula;

[0039] When the detection signal is lower than the lowest action voltage signal of the input terminal, a low level signal is output to control the OLED power supply control unit to cut off the power supply of the voltage output terminal.

[0040] Specifically, the input sampling unit is the front-end processing component of the protection circuit. Its primary task is to rectify the input power supply signal. This means that regardless of whether the input power supply signal is AC or DC, the input sampling unit can convert it into a DC signal suitable for subsequent circuit processing to drive the OLED display. Through the input sampling unit's rectification, we ensure that the subsequent circuit receives a stable and reliable DC detection signal AC-DET. Next, the AC detection unit is responsible for further processing and analysis of this rectified detection signal AC-DET. It compares the detection signal AC-DET with a preset reference voltage signal VREF, which is set based on the normal operating requirements of the OLED display. The AC detection unit compares the detection signal AC-DET with the reference voltage signal VREF to determine whether the power supply is normal. If the detection signal AC-DET is lower than the preset minimum operating voltage signal (the ratio of the minimum operating voltage signal is calculated as: [(R1 + R2) / R5] × VREF), the AC detection unit will determine that an abnormal power outage has occurred. At this point, the AC detection unit will output a corresponding low-level signal to the OLED power control unit. Finally, the OLED power supply control unit is the executive portion of the protection circuit. Upon receiving a low-level signal from the AC detection unit, it immediately shuts off power to the voltage output terminal OUT-A, thereby shutting off power to the OLED display. This step protects the OLED display from damage. If the power supply unexpectedly loses power while the OLED display continues to operate, the internal circuits and components could be damaged by the insufficient power supply. By promptly shutting off power to the OLED power supply control unit, we ensure that the OLED display is properly protected in the event of a power outage, thereby extending its lifespan and improving its stability.

[0041] In summary, this OLED display input abnormal power-off protection circuit achieves comprehensive protection for the OLED display in the event of power supply abnormality through the close cooperation of the input sampling unit, AC detection unit and OLED power supply control unit, which not only improves the stability and reliability of the OLED display, but also brings a better user experience to users.

[0042] Example 2:

[0043] On the basis of Example 1, combined with the attached Figure 2 As shown, the input sampling unit includes: a diode D1, a diode D2, a resistor R1 and a resistor R2;

[0044] After the resistor R1 and the resistor R2 are connected in series, one end is connected to the detection signal, and the other end is connected to the cathode of the diode D1 and the cathode of the diode D2. The anodes of the diode D1 and the diode D2 are connected to the power supply signal.

[0045] Specifically, the input sampling unit consists of four main components: diode D1, diode D2, resistor R1, and resistor R2. These components, through a specific connection, collectively perform the rectification task. First, resistors R1 and R2 are connected in series. This means that when current passes through these two resistors, it flows through them sequentially, creating a voltage divider effect. The input power signal is divided by the upper bias circuit formed by R1 and R2 and the lower bias resistor R5, resulting in the detection signal AC-DET. This voltage divider helps adjust the input power signal to a range suitable for subsequent circuit processing. Next, one end of the series connection of resistors R1 and R2 is connected to the detection signal AC-DET. This detection signal AC-DET is the output of the rectification process and represents the status of the input power signal. This signal is transmitted to the AC detection unit for further comparison and judgment. Meanwhile, the other end of the series connection of resistors R1 and R2 is connected to the cathodes of diodes D1 and D2. A diode is an electronic component with unidirectional conductivity: its cathode is the input terminal for current, and its anode is the output terminal for current. Here, the cathodes of diodes D1 and D2 are connected to the series connection of resistors R1 and R2, forming part of a rectifier circuit. Finally, the anodes of diodes D1 and D2 are connected to the AC power signal. During the positive half-cycle of the AC power signal, diode D1 conducts, and current forms a loop through D1 and resistors R1 and R2, charging the detection signal AC-DET. During the negative half-cycle of the AC power signal, diode D2 conducts, and current forms a loop through D2 and resistors R1 and R2, similarly charging the detection signal AC-DET. Due to the unidirectional conductivity of the diodes, regardless of the positive or negative sign of the AC power signal, the rectification effect of D1 and D2 ensures that the detection signal AC-DET always remains a positive DC signal.

[0046] As an embodiment, the AC detection unit includes: an operational amplifier, an isolation photoelectric coupler, resistors R4, R5, R6, R7 and R8, and a MOS tube Q1;

[0047] A first end of the capacitor C2 and a first pin of the operational amplifier are connected to a power supply voltage and to a first end of the resistor R3 , and a second end of the capacitor C2 and a second pin of the operational amplifier are grounded;

[0048] The second end of the resistor R3 is connected to the first end of the resistor R4 and the LED anode of the isolation photoelectric coupler, and the second end of the resistor R4 is connected to the LED cathode of the isolation photoelectric coupler and the drain of the MOS tube Q1;

[0049] A first end of the resistor R6 is connected to a first end of the resistor R5 and a detection signal, a second end of the resistor R6 is connected to a first end of the capacitor C1 and a non-inverting input terminal of the operational amplifier, and a second end of the resistor R5 and a second end of the capacitor C1 are grounded;

[0050] A first end of resistor R7 is connected to the preset reference voltage signal, a second end of resistor R7 is connected to the inverting input end of the operational amplifier, an output end of the operational amplifier is connected to a first end of resistor R8, a second end of resistor R8 is connected to a first end of resistor R9 and a first end of capacitor C3 and to the gate of MOS transistor Q1, and a second end of resistor R9, a second end of capacitor C3, and a source of MOS transistor Q1 are grounded.

[0051] Specifically, the first end of capacitor C2 is connected to the first pin of operational amplifier U1-A, and is also connected to the power supply voltage and the first end of resistor R3. The second end of capacitor C2 is connected to the second pin of operational amplifier U1-A and ground. This connection constitutes the power supply filter circuit of operational amplifier U1-A, which stabilizes the operating voltage of operational amplifier U1-A and reduces the impact of power supply noise. Next, the second end of resistor R3 is connected to the first end of resistor R4 and the anode of the LED of the isolation optocoupler U2. The second end of resistor R4 is connected to the cathode of the LED of the isolation optocoupler U2 and the drain of MOS transistor Q1. When the AC power signal is normal, current flows through resistors R3 and R4 and the LED of the isolation optocoupler U2, causing the LED to emit light. This light signal is received by the photosensor of the isolation optocoupler U2 and converted into an electrical signal, which further controls the conduction or cutoff of MOS transistor Q1. Regarding the processing of detection signal AC-DET, the first end of resistor R6 is connected to the first end of resistor R5 and the detection signal AC-DET. The second end of resistor R6 is connected to the first end of capacitor C1 and the non-inverting input of operational amplifier U1-A. The second end of resistor R5 and the second end of capacitor C1 are both grounded. This connection constitutes the signal input circuit of operational amplifier U1-A, which amplifies the detection signal AC-DET and transmits it to operational amplifier U1-A for comparison. To compare the detection signal AC-DET, the first end of resistor R7 is connected to a preset reference voltage signal VREF, and the second end of resistor R7 is connected to the inverting input of operational amplifier U1-A. Operational amplifier U1-A compares the signals at its non-inverting and inverting inputs and outputs a corresponding control signal based on the comparison result. Finally, the output of operational amplifier U1-A is connected to the first end of resistor R8. The second end of resistor R8 is connected to the first end of resistor R9 and the first end of capacitor C3, and is also connected to the gate of MOS transistor Q1. The second end of resistor R9, the second end of capacitor C3, and the source of MOS transistor Q1 are all grounded. This connection method constitutes a driving circuit of the MOS transistor Q1, which is used to control the on or off state of the MOS transistor Q1 according to the output signal of the operational amplifier U1-A.

[0052] When the AC power signal is normal, the LED in the isolated optocoupler U2 illuminates, and the photosensor receives the light signal and converts it into an electrical signal, turning on MOS transistor Q1. At this point, the OLED display's power supply circuit operates normally. When the AC power signal is abnormal, the LED in the isolated optocoupler U2 does not illuminate, the photosensor generates no electrical signal, and MOS transistor Q1 turns off. This shuts off the OLED display's power supply circuit, protecting the display from damage.

[0053] It should be noted that the circuit is composed of an integrating circuit composed of resistor R6 and capacitor C1, which integrates the input signal and filters out interference. Adjusting capacitor C1 can adjust the turn-off time of MOS tubes Q5 and Q6 after the input power is abnormally cut off, thereby controlling the delay time of the voltage output terminal OUT-A after the input power is abnormally cut off, so as to achieve the desired delay effect. In this example, it is required that the voltage output terminal OUT-A should be turned off within 10mS after the input power is cut off. Figure 3 As shown in the figure, in this example, the voltage output terminal OUT-A should be turned off within 10ms after the input power is turned off, so that V3 can be turned off more than 75ms earlier than V1 and V2.

[0054] Furthermore, the detection unit further includes: a voltage stabilizing diode Z1, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor RF24, a resistor R14, a resistor R15, a capacitor C4, a capacitor C5, a capacitor C6, a MOS transistor Q2, a MOS transistor Q3 and a MOS transistor Q4;

[0055] A first end of the resistor R10 is connected to a first operating voltage, a second end of the resistor R10 is connected to the gate of the MOS transistor Q2, the first end of the capacitor C4, the first end of the resistor R11, the cathode of the voltage-stabilizing diode Z1, and the collector of the photodetector in the isolation photoelectric coupler U2, a drain of the MOS transistor Q3 is connected to the level signal terminal, the second end of the resistor R12, and the drain of the MOS transistor Q2, a first end of the resistor R12 is connected to the second operating voltage, and the emitter of the photodetector in the isolation photoelectric coupler, the anode of the voltage-stabilizing diode Z1, the second end of the resistor R11, the second end of the capacitor C4, and the source of the MOS transistor Q2 are grounded;

[0056] A first end of the resistor RF24 is connected to the first operating voltage, a second end of the resistor RF24 is connected to the drain of the MOS transistor Q4, the first end of the resistor R13, the first end of the capacitor C5, and the gate of the MOS transistor Q3, and a source of the MOS transistor Q3, a source of the MOS transistor Q4, the second end of the resistor R13, and the second end of the capacitor C5 are grounded;

[0057] The first end of the resistor R15 is connected to the input control signal, the second end of the resistor R15 is connected to the gate of the MOS transistor Q4, the first end of the resistor R14 and the first end of the capacitor C6, and the second end of the resistor R14 and the second end of the capacitor C6 are grounded.

[0058] Specifically, the first end of resistor R10 is connected to the first operating voltage ELVDD, providing a stable voltage source for the circuit. The second end of resistor R10 is connected to the gate of MOS transistor Q2, the first end of capacitor C4, the first end of resistor R11, the cathode of Zener diode Z1, and the collector of the photodetector in the isolating optocoupler U2. Zener diode Z1 protects the circuit, preventing damage to components caused by excessive voltage. Next, the drain of MOS transistor Q3 is connected to the level signal terminal SW-OFF, the second end of resistor R12, and the drain of MOS transistor Q2. The first end of resistor R12 is connected to the second operating voltage VDD. VDD+ is an auxiliary power supply. If this voltage is lost, the capacitor at the output of the power supply system ensures that Q5 and Q6 remain disconnected, even if this power supply loses voltage, as long as the power supply system ELVDD has not discharged below the threshold voltage of Q2. This power supply's primary function is to maintain the power supply system's normal input power supply and the on state of the standby signal ENA (i.e., the input control signal), thereby maintaining the conduction of Q7 and thus the conduction of electronic switches Q5 and Q6, thus illuminating the OLED display. Simultaneously, the emitter of the photodetector in the isolating optocoupler U2, the anode of the Zener diode Z1, the second end of the resistor R11, the second end of the capacitor C4, and the source of the MOS transistor Q2 are all grounded. This connection ensures circuit stability and safety. The first end of resistor RF24 is connected to the first operating voltage ELVDD, the output voltage of the power supply system and the power supply for the OLED display's light-emitting unit. Controlled by electronic switches Q5 and Q6, V3 is generated to power the OLED display. The second end of resistor RF24 is connected to the drain of MOS transistor Q4, the first end of resistor R13, the first end of capacitor C5, and the gate of MOS transistor Q3. ELVDD is connected to the gate of Q2 to ensure that when the power system output filter capacitor discharges to a voltage below the turn-on voltage of Q2 MOS transistor (for example, MOS transistors, Q2's VTH turn-on threshold is generally 1.5V or 2.5V, or 0.5-0.7V if Q2 uses a transistor). This ensures that after the power system loses input voltage, electronic switches Q5 and Q6 remain in the off state. (This is also controlled by the AC detection circuit. When the AC input state is normal, the Q2 control electrode will be pulled down by the optocoupler to below its turn-on voltage, keeping the electronic switch in the on state.) At the same time, the source of MOS transistor Q3, the source of MOS transistor Q4, the second end of resistor R13, and the second end of capacitor C5 are all grounded, ensuring stable operation of the circuit. Finally, the first end of resistor R15 is connected to the input control signal ENA, providing the control signal input for the circuit. The second end of the resistor R15 is connected to the gate of the MOS transistor Q4, the first end of the resistor R14, and the first end of the capacitor C6. This connection allows the input control signal ENA to control the conduction state of the MOS transistor Q4 through the resistor R15.At the same time, the second end of the resistor R14 and the second end of the capacitor C6 are both grounded, providing a stable grounding environment for the circuit.

[0059] It should be noted that in order to ensure that the OLED display can quickly cut off the OLED power supply when it is in normal standby mode and prevent false triggering from causing screen flickering, ghosting and other phenomena when the OLED display is in standby mode, the circuit adds a fast power on / off circuit composed of MOS tubes Q3 and Q4. When the system issues a shutdown command, the MOS tube Q4 input is low, the MOS tube Q3 input becomes high, and the MOS tube Q3 is turned on.

[0060] In summary, the detection unit achieves comprehensive circuit detection and control through the ingenious combination and connection of voltage-stabilizing diodes, resistors, capacitors, and MOSFETs. When a voltage or signal abnormality occurs within the circuit, the detection unit quickly responds and disconnects the circuit, protecting components from damage. This design not only improves circuit safety and stability but also provides strong support for subsequent circuit design and application.

[0061] As an embodiment, the OLED power supply control unit includes: a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor RS3, a resistor RS4, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a voltage regulator diode Z2, a MOS transistor Q5 and a MOS transistor Q6;

[0062] The first end of the resistor R18, the first end of the capacitor C8, the first end of the capacitor C10, the cathode of the voltage stabilizing diode Z2, the source of the MOS transistor Q5, and the source of the MOS transistor Q6 are connected to the first operating voltage. The second end of the capacitor C10 is connected to the first end of the capacitor C9, the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, and the positive terminal of the control signal output.

[0063] The second end of capacitor C8 is connected to the gate of MOS transistor Q5, the gate of MOS transistor Q6, the anode of Zener diode Z2, the second end of capacitor C9, and the first end of resistor R19. The second end of resistor R18 and the second end of resistor R19 are connected to the drain of MOS transistor Q6. The first end of resistor R16 is connected to the level signal terminal. The second end of resistor R16 is connected to the first end of resistor R17, the first end of capacitor C7, and the gate of MOS transistor Q7. Resistors RS3 and RS4 are connected in parallel with one end connected to the second end of resistor R17, the second end of capacitor C7, the source of MOS transistor Q7, and the negative terminal of the control signal output. The other end is grounded.

[0064] After the resistor R20, the resistor R21 and the resistor R22 are connected in parallel, one end is connected to the voltage output positive end, and the other end is connected to the voltage output negative end. The voltage output positive end and the voltage output negative end constitute the voltage output end.

[0065] Specifically, resistor R18, capacitor C8, capacitor C10, Zener diode Z2, and the source electrodes of MOS transistors Q5 and Q6 are all connected to the first operating voltage ELVDD. The second end of capacitor C10 is connected to the first end of capacitor C9, the drain electrodes of MOS transistors Q5 and Q6, and the positive control signal output terminal. This connection ensures stable control signal output and, in the event of circuit anomalies, capacitors C10 and C9 can also provide buffering and filtering. Next, the second end of capacitor C8 is connected to the gate electrodes of MOS transistors Q5 and Q6, the anode of Zener diode Z2, the second end of capacitor C9, and the first end of resistor R19. This connection ensures stable control of the gate voltages of MOS transistors Q5 and Q6. Furthermore, the second ends of resistors R18 and R19 are both connected to the drain electrode of MOS transistor Q6. This design helps regulate the current and voltage in the circuit, ensuring a stable power supply for the OLED. The first end of resistor R16 is connected to the level signal terminal SW-OFF. A level signal is a signal used to control circuit switching and typically has two states: high and low. The second end of resistor R16 is connected to the first end of resistor R17, the first end of capacitor C7, and the gate of MOS transistor Q7. This connection allows the level signal to control the conduction state of MOS transistor Q7 through resistors R16 and R17. When the level signal is high, MOS transistor Q7 is turned on; when the level signal is low, MOS transistor Q7 is turned off. Furthermore, resistors RS3 and RS4 are connected in parallel, with one end connected to the second end of resistor R17, the second end of capacitor C7, the source of MOS transistor Q7, and the negative terminal of the control signal output, and the other end connected to ground. This design helps stabilize the voltage and current in the circuit and improves its anti-interference ability. Finally, resistors R20, R21, and R22 are connected in parallel, with one end connected to the positive voltage output terminal and the other end connected to the negative voltage output terminal. This connection ensures a more stable voltage output to the OLED, ensuring its proper operation.

[0066] It should be noted that the PMOS drive voltage divider circuit and limiter circuit composed of the resistor R18, the resistor R19 and the voltage stabilizing diode Z2 protect the MOS tubes Q5 and Q6 to prevent the PMOS drive from being damaged by overvoltage.

[0067] In summary, the OLED power supply control unit achieves stable power supply and control for the OLED through the ingenious combination and connection of multiple resistors, capacitors, voltage-stabilizing diodes, and MOS transistors. This design not only improves the stability and reliability of the circuit, but also provides a strong guarantee for the normal operation of the OLED.

[0068] After the input sampling circuits D1 and D2 are rectified and isolated, the input power supply signal is divided by the upper bias circuit composed of R1 and R2 and the lower bias resistor R5 to obtain the detection signal AC-DET. After the detection signal AC-DET enters the operational amplifier U1-A, it is compared with the reference voltage signal VREF. The output end of the operational amplifier U1-A outputs the minimum action voltage. When the detection signal AC-DET is lower than the minimum action voltage, the output end outputs a low level, the MOS tube Q1 is cut off, the isolation optocoupler U2 is cut off, the MOS tube Q2 input becomes a high level, the MOS tube Q2 is turned on, the level signal end SW-OFF becomes a low level, the electronic switch circuit Q7 input is low level, at this time the MOS tube Q7 is cut off, the Q5 and Q6 electronic switches composed of PMOS are cut off, the voltage output end OUT-A loses voltage, which means that the OLED power supply loses voltage and the OLED display is in a black screen state.

[0069] As an embodiment, it further includes: a power supply system, which converts the power supply signal into an operating voltage signal to output to the OLED power supply control unit; wherein the power supply signal includes an AC power signal and a DC power signal.

[0070] Specifically, the power supply system is a highly integrated electronic component that can process various forms of power supply signals, including AC power signals and DC power signals. AC power signals are usually the mains electricity used in our homes or commercial environments, and their voltage and current direction change periodically. DC power signals, on the other hand, refer to power sources in which the voltage and current direction remain constant, such as those commonly found in battery-powered devices. Through internal circuit design and conversion mechanisms, the power supply system first performs a series of processes such as rectification, filtering, and voltage stabilization on these input power signals. The rectification process converts AC power into DC power, filtering removes clutter and interference in the power supply, and voltage stabilization ensures the stability and accuracy of the output voltage. After these processes, the power supply signal, which may have been unstable or unsuitable for direct use, is converted into the stable operating voltage signal required by the OLED power supply control unit.

[0071] Although the present invention is described herein with reference to the illustrative embodiments of the present invention, the above embodiments are merely preferred embodiments of the present invention, and the embodiments of the present invention are not limited to the above embodiments. It should be understood that those skilled in the art can design many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. An OLED display screen input abnormal power-off protection circuit, characterized in that: include: Input sampling unit, AC detection unit and OLED power supply control unit, The input sampling unit is used to rectify the input power supply signal and output a detection signal to the AC detection unit; The AC detection unit compares the detection signal with a preset reference voltage signal to determine whether the detection signal is lower than a minimum operating voltage signal, and outputs a corresponding level signal to the OLED power supply control unit, wherein the minimum operating voltage signal is determined according to a preset ratio calculation formula; When the detection signal is lower than the minimum action voltage signal of the input terminal, a low level signal is output to control the OLED power supply control unit to cut off the power supply of the OLED display screen.

2. The OLED display screen input abnormal power-off protection circuit according to claim 1, characterized in that: The input sampling unit includes: a diode D1, a diode D2, a resistor R1 and a resistor R2; After the resistor R1 and the resistor R2 are connected in series, one end is connected to the detection signal, and the other end is connected to the cathode of the diode D1 and the cathode of the diode D2. The anodes of the diode D1 and the diode D2 are connected to the power supply signal.

3. The OLED display screen input abnormal power-off protection circuit according to claim 2, characterized in that: The AC detection unit includes: an operational amplifier, an isolation photoelectric coupler, resistors R4, R5, R6, R7 and R8, and a MOS tube Q1; A first end of the capacitor C2 and a first pin of the operational amplifier are connected to a power supply voltage and to a first end of the resistor R3 , and a second end of the capacitor C2 and a second pin of the operational amplifier are grounded; The second end of the resistor R3 is connected to the first end of the resistor R4 and the LED anode of the isolation photoelectric coupler, and the second end of the resistor R4 is connected to the LED cathode of the isolation photoelectric coupler and the drain of the MOS tube Q1; A first end of the resistor R6 is connected to a first end of the resistor R5 and a detection signal, a second end of the resistor R6 is connected to a first end of the capacitor C1 and a non-inverting input terminal of the operational amplifier, and a second end of the resistor R5 and a second end of the capacitor C1 are grounded; A first end of resistor R7 is connected to the preset reference voltage signal, a second end of resistor R7 is connected to the inverting input end of the operational amplifier, an output end of the operational amplifier is connected to a first end of resistor R8, a second end of resistor R8 is connected to a first end of resistor R9 and a first end of capacitor C3 and to the gate of MOS transistor Q1, and a second end of resistor R9, a second end of capacitor C3, and a source of MOS transistor Q1 are grounded.

4. The OLED display screen input abnormal power-off protection circuit according to claim 3, characterized in that: The detection unit further includes: a voltage stabilizing diode Z1, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor RF24, a resistor R14, a resistor R15, a capacitor C4, a capacitor C5, a capacitor C6, a MOS transistor Q2, a MOS transistor Q3 and a MOS transistor Q4; A first end of the resistor R10 is connected to a first operating voltage, a second end of the resistor R10 is connected to the gate of the MOS transistor Q2, the first end of the capacitor C4, the first end of the resistor R11, the cathode of the voltage-stabilizing diode Z1, and the collector of the photodetector in the isolation photoelectric coupler, a drain of the MOS transistor Q3 is connected to the level signal terminal, the second end of the resistor R12, and the drain of the MOS transistor Q2, a first end of the resistor R12 is connected to a second operating voltage, and an emitter of the photodetector in the isolation photoelectric coupler, an anode of the voltage-stabilizing diode Z1, the second end of the resistor R11, the second end of the capacitor C4, and the source of the MOS transistor Q2 are grounded; A first end of the resistor RF24 is connected to the first operating voltage, a second end of the resistor RF24 is connected to the drain of the MOS transistor Q4, the first end of the resistor R13, the first end of the capacitor C5, and the gate of the MOS transistor Q3, and a source of the MOS transistor Q3, a source of the MOS transistor Q4, the second end of the resistor R13, and the second end of the capacitor C5 are grounded; The first end of the resistor R15 is connected to the input control signal, the second end of the resistor R15 is connected to the gate of the MOS transistor Q4, the first end of the resistor R14 and the first end of the capacitor C6, and the second end of the resistor R14 and the second end of the capacitor C6 are grounded.

5. The OLED display screen input abnormal power-off protection circuit according to claim 4, characterized in that: The OLED power supply control unit includes: a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor RS3, a resistor RS4, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a voltage regulator diode Z2, a MOS transistor Q5 and a MOS transistor Q6; The first end of the resistor R18, the first end of the capacitor C8, the first end of the capacitor C10, the cathode of the voltage stabilizing diode Z2, the source of the MOS transistor Q5, and the source of the MOS transistor Q6 are connected to the first operating voltage. The second end of the capacitor C10 is connected to the first end of the capacitor C9, the drain of the MOS transistor Q5, the drain of the MOS transistor Q6, and the positive terminal of the control signal output. The second end of capacitor C8 is connected to the gate of MOS transistor Q5, the gate of MOS transistor Q6, the anode of Zener diode Z2, the second end of capacitor C9, and the first end of resistor R19. The second end of resistor R18 and the second end of resistor R19 are connected to the drain of MOS transistor Q6. The first end of resistor R16 is connected to the level signal terminal. The second end of resistor R16 is connected to the first end of resistor R17, the first end of capacitor C7, and the gate of MOS transistor Q7. Resistors RS3 and RS4 are connected in parallel with one end connected to the second end of resistor R17, the second end of capacitor C7, the source of MOS transistor Q7, and the negative terminal of the control signal output. The other end is grounded. After the resistor R20, the resistor R21 and the resistor R22 are connected in parallel, one end is connected to the voltage output positive end, and the other end is connected to the voltage output negative end. The voltage output positive end and the voltage output negative end constitute the voltage output end.

6. The OLED display screen input abnormal power-off protection circuit according to claim 1, characterized in that: Also includes: A power supply system converts the power supply signal into an operating voltage signal to output to the OLED power supply control unit; wherein the power supply signal includes an AC power signal and a DC power signal.

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