Electrostatic discharge circuit for ultra-high-definition two-path image divider

Abstract

According to the electrostatic discharge circuit for the ultra-high-definition two-path image divider, the electrostatic detection circuit detects an electrostatic charge signal of the space where the circuit board is located, the electrostatic charge signal is converted into voltage, the change rate of the voltage is calculated, and when the voltage is higher than the voltage stabilization value 1.2 V of a voltage-regulator tube TVS4 and smaller than + 1.4 V, the electrostatic discharge circuit controls static electricity to be discharged through an anti-electricity ring in time, so that the circuit is safe and reliable. When the voltage value of the electrostatic protection circuit is 1.2 V higher than the voltage stabilization value of a voltage-regulator tube TVS4 and 3.3 V higher than the voltage stabilization value of the voltage-regulator tube TVS4, static electricity is discharged to the ground through a discharge tube BV1, a piezoresistor and a discharge capacitor C7, meanwhile, a voltage change rate signal accelerates connection of the discharge tube BV1 through inverse time limit, and the electrostatic protection circuit protects a post-stage chip by arranging a ceramic discharge tube TVS1. RGB888 signals of the two interfaces are respectively connected to the ground through transient suppression diodes TVS3 and TVS2 to perform ESD protection, and then are respectively connected to the image processing chip through a buffer F1 / an inverter F2 and a grounding capacitor to adjust signal level and avoid transmission crosstalk, and IO ports of the image processing chip are respectively and reversely connected with diodes, potentiometers and anti-electricity rings to perform discharge.

Description

Technical Field

[0001] This utility model relates to the field of video processing technology, and in particular to an electrostatic discharge circuit for an ultra-high-definition two-channel image splitter. Background Technology

[0002] Existing technology: The ultra-high-definition dual-channel image splitter with application number 202020315433.7 converts the HDMI signal into an RGB888 signal and transmits it to the image processing circuit. The image processing circuit adopts the MDIN400 new generation image processing chip, which combines the two RGB888 signals into a single TTL signal through a scaler. The signal conversion chip converts the TTL signal into an HDMI signal and transmits it to the display, thereby improving the output resolution of the image splitter.

[0003] Image processing chips are responsible for processing and optimizing image data, playing a crucial role in the clarity of the output image. During use, a certain amount of charge can accumulate in the external environment or internal structure of the chip. The instantaneous large current value of the accumulated charge can burn out the chip. Electrostatic discharge (ESD) is the main cause of chip failure. Current technology uses series diodes in the internal I / O ports of the chip for electrostatic protection, or external TVS diodes for electrostatic protection. Although this provides electrostatic protection, it does not eliminate or release the static electricity. During prolonged ESD events, the internal or external protection may be overloaded and damage the chip. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide an electrostatic discharge circuit for an ultra-high-definition dual-channel image splitter. By providing electrostatic protection for the image processing chip and detecting the static electricity in the space where the circuit board is located, it promptly discharges the static electricity through anti-static rings, varistors, and discharge capacitors, thus achieving better electrostatic protection performance.

[0005] The technical solution includes a first HDMI receiving circuit and a second HDMI receiving circuit, and an image processing chip. The first HDMI receiving circuit and the second HDMI receiving circuit are respectively connected to the image processing chip. An electrostatic protection circuit is set between the first HDMI receiving circuit and the image processing chip and the second HDMI receiving circuit and the image processing chip. An electrostatic detection circuit and an electrostatic discharge circuit are set on the circuit board.

[0006] The electrostatic detection circuit is connected to the electrostatic protection circuit and the electrostatic release circuit, respectively.

[0007] Preferably, the electrostatic discharge circuit includes a capacitor C5, a Zener diode TVS6, and a resistor R6. The other end of the capacitor C5 is connected to the base of transistor Q1 and the negative terminal of Zener diode TVS5, respectively. The emitter of transistor Q1 is connected to a +1.4V power supply. The collector of transistor Q1 is connected to the positive terminal of electrolytic capacitor E2 and the adjustable terminal of potentiometer RP1, respectively. The positive terminal of Zener diode TVS5 is connected to the base of discharge diode BV1, the positive terminal of Zener diode TVS6, the other end of resistor R6, and one end of grounding resistor R7, respectively. The collector of discharge diode BV1 is connected to the signal from transient suppression diode TVS to ground. The emitter of discharge diode BV1 is connected to the upper end of the first varistor RT1. The lower end of the first varistor RT1 discharges static electricity to ground through the varistor of the second varistor RT2 and the discharge capacitor C7, respectively.

[0008] Preferably, the electrostatic discharge protection circuit includes ceramic discharge tubes TVS1, TVS2, and TVS3. Ceramic discharge tube TVS1 is disposed between the RGB888 signals of the two interfaces output by the first HDMI receiving circuit. The RGB888 signals of the two interfaces are connected to ground via transient suppression diodes TVS3 and TVS2, respectively. The RGB888 signal of one of the two interfaces is connected to one I / O port of the image processing chip via buffer F1 and grounding capacitor C1. The RGB888 signal of the other interface is connected to the second I / O port of the image processing chip via inverter F2 and grounding capacitor C2. The negative terminal of diode D4 and the positive terminal of diode D3 are connected to the first I / O port and the second I / O port of the image processing chip, respectively. The positive terminal of diode D4 and the negative terminal of diode D3 are connected to one end of potentiometer RP1. The other end of potentiometer RP1 is connected to the anti-static ring.

[0009] This invention uses an electric field sensor to detect the electrostatic charge signal in the space where the circuit board is located. The signal is converted into voltage by a transimpedance amplifier, and the rate of change of voltage is calculated by an integrator. The voltage is detected by a Zener diode (TVS4). When the voltage is higher than the Zener diode's regulation value of 1.2V but less than +1.4V, transistor Q1 is turned on, and the output voltage is applied to the adjustable terminal of potentiometer RP1. By adjusting the resistance of potentiometer RP1, the electrostatic charge is discharged in time through the anti-static ring. When the voltage is higher than the Zener diode's regulation value of 1.2V but higher than the Zener diode's regulation value of 3.3V, discharge tube BV1 is turned on. The electrostatic charge suppressed to ground by the transient suppression diode (ESD) is discharged to ground through discharge tube BV1, varistor, and discharge capacitor C7. At the same time, the rate of change of voltage signal is applied to the base of discharge tube BV1 in an inverse-time manner through Zener diode TVS6 and resistor R6, which accelerates the turn-on of discharge tube BV1 and discharges the electrostatic charge to ground in time.

[0010] A ceramic discharge tube (TVS1) is placed between the RGB888 signals of the two interfaces output by the first HDMI receiving circuit to protect the subsequent chips. The RGB888 signals of the two interfaces are connected to ground via transient suppression diodes (TVS3 and TVS2) for ESD protection. The RGB888 signal of one interface is connected to one I / O port of the image processing chip via buffer F1 and grounding capacitor C1. The RGB888 signal of the other interface is connected to the second I / O port of the image processing chip via inverter F2 and grounding capacitor C2. Adjusting the signal level changes the logic level of the RGB888 signal to avoid transmission crosstalk. The first and second I / O ports of the image processing chip are reverse-connected to diodes D3 and D4 for conduction protection. With the help of a potentiometer to adjust the resistance value to the anti-static ring for discharge, the electrostatic charge can be discharged safely and reliably. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the image distortion detection circuit of this utility model.

[0012] Figure 2 This is a module diagram of the present utility model. Detailed Implementation

[0013] For the purposes of this utility model, the foregoing and other technical contents, features and effects are described in conjunction with the appendix below. Figures 1 to 2 The detailed description of the embodiments will make this clear. All structural details mentioned in the following embodiments are based on the accompanying drawings.

[0014] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0015] An electrostatic discharge circuit for an ultra-high-definition dual-channel image splitter includes a first HDMI receiving circuit and a second HDMI receiving circuit, and an image processing chip (MDIN400). The first HDMI receiving circuit and the second HDMI receiving circuit are respectively connected to the image processing chip. An electrostatic protection circuit is set between the first HDMI receiving circuit and the image processing chip and the second HDMI receiving circuit and the image processing chip. An electrostatic detection circuit and an electrostatic discharge circuit are set on the circuit board.

[0016] The electrostatic detection circuit is connected to the electrostatic protection circuit and the electrostatic release circuit, respectively.

[0017] Based on the above technical solution, the electrostatic detection circuit uses an electric field sensor to detect the electrostatic charge signal in the space where the circuit board is located. The signal is converted into voltage by a transimpedance amplifier consisting of a series capacitor C3, resistor R1, operational amplifier AR1, and a parallel capacitor C4 and resistor R2. One voltage path directly enters the electrostatic discharge circuit, while the other path passes through an integrator composed of operational amplifier AR2, parallel resistors R2-R5, and capacitor C6 to calculate the rate of change of voltage before entering the electrostatic discharge circuit. Capacitor C3 is included; one end of C3 is connected to the electrostatic signal detected by the electric field sensor, and the other end of C3 is connected to one end of resistor R1. The other end of resistor R1 is connected to the operational amplifier... The inverting input of operational amplifier AR1 is connected to one end of resistor R2 and one end of capacitor C4. The non-inverting input of operational amplifier AR1 is connected to ground. The output of operational amplifier AR1 is connected to the other end of resistor R2, the other end of capacitor C4, the negative terminal of Zener diode TVS4, one end of resistor R4, and one end of capacitor C5. The other end of resistor R4 is connected to the inverting input of operational amplifier AR2, one end of resistor R3, and one end of capacitor C6. The non-inverting input of operational amplifier AR2 is connected to ground through resistor R5. The output of operational amplifier AR2 is connected to the other end of resistor R3, the other end of capacitor C6, the negative terminal of Zener diode TVS6, and one end of resistor R6.

[0018] Based on the above technical solution, the electrostatic discharge circuit detects the voltage through the Zener diode TVS4. When the voltage is higher than the Zener diode TVS4's regulated voltage of 1.2V but lower than +1.4V, that is, when the chip pin forms a path with ground, the accumulated charge is transferred. When the peak current through the integrated circuit can reach several 400mA, the transistor Q1 conducts, and the output voltage is applied to the adjustable terminal of potentiometer RP1. By adjusting the resistance of potentiometer RP1 (a voltage-controlled resistor, where the higher the voltage, the lower the resistance), the electrostatic discharge is controlled to be discharged in time through the anti-static ring. When the voltage is higher than the Zener diode TVS4's regulated voltage of 1.2V but higher than the Zener diode TVS4's regulated voltage of 3.3V, that is, when the chip pin forms a path with ground, the accumulated charge is transferred, and the peak current through the integrated circuit can reach several A, the discharge tube BV1 is turned on. The electrostatic discharge protected by the transient suppression diode ESD is discharged through the discharge tube BV1, the varistor, and the discharge capacitor C7. Static electricity is discharged to ground. Simultaneously, the voltage change rate signal is applied inversely to the base of the discharge tube BV1 via the Zener diode TVS6 and resistor R6, accelerating the connection of the discharge tube BV1 and promptly discharging static electricity to ground. This is achieved through capacitor C5, the Zener diode TVS6, and resistor R6. The other end of capacitor C5 is connected to the base of transistor Q1 and the negative terminal of the Zener diode TVS5. The emitter of transistor Q1 is connected to the +1.4V power supply, and the collector of transistor Q1 is connected to the positive terminal of electrolytic capacitor E2. The adjustable terminal of potentiometer RP1 and the positive terminal of Zener diode TVS5 are respectively connected to the base of discharge diode BV1, the positive terminal of Zener diode TVS6, the other end of resistor R6, and one end of grounding resistor R7. The collector of discharge diode BV1 is connected to the signal from transient suppression diode TVS to ground. The emitter of discharge diode BV1 is connected to the upper end of the first varistor RT1. The lower end of the first varistor RT1 is discharged to ground through the varistor of the second varistor RT2 and the discharge capacitor C7.

[0019] Based on the above technical solution, the electrostatic discharge (ESD) protection circuit is used to protect the signals input to the image processing chip from electrostatic discharge. The following explanation uses the RGB888 signals from the two interfaces output by the first HDMI receiving circuit as an example. A ceramic discharge tube (TVS1, such as BC201N) is placed between the RGB888 signals from the two interfaces output by the first HDMI receiving circuit. Normally, it is in a high-resistance state; during a surge, the high-resistance state changes to a low-resistance state to discharge, protecting the downstream chip. The RGB888 signals from the two interfaces are connected to ground via transient suppression diodes (TVS3 and TVS2) for ESD protection. The RGB888 signal from one interface is connected to one I / O port of the image processing chip via buffer F1 and ground capacitor C1. The RGB888 signal from the other interface is connected to the second I / O port of the image processing chip via inverter F2 and ground capacitor C2 (the second I / O port of the image processing chip can be recovered by inversion). Adjusting the signal level changes the logic level of the RGB888 signal to avoid transmission crosstalk. The cathode of diode D4 and the anode of diode D3 are connected to the first I / O port and the second I / O port of the image processing chip, respectively. The anode of diode D4 and the cathode of diode D3 are connected to one end of potentiometer RP1. The other end of the potentiometer RP1 is connected to an anti-static ring, with diodes D3 and D4 reverse-connected for conduction protection. A potentiometer with variable resistance is used to discharge static charge through the anti-static ring, ensuring safe and reliable discharge of large amounts of static charge. It should be noted that the structure of diodes D3 and D4, the potentiometer, and the anti-static ring can also be implemented at the power port of the image processing chip. To further enhance electrostatic protection, an anti-static coating, including ceramic discharge tubes TVS1, TVS2, and TVS3, can be applied to the image processing chip area of ​​the circuit board. Ceramic discharge tube TVS1 is positioned between the RGB888 signals of the two interfaces output by the first HDMI receiving circuit. The RGB888 signals from the two interfaces are connected to ground via transient suppression diodes TVS3 and TVS2, respectively. The RGB888 signal from one of the interfaces is connected to one I / O port of the image processing chip via buffer F1 and grounding capacitor C1. The RGB888 signal from the other interface is connected to the second I / O port of the image processing chip via inverter F2 and grounding capacitor C2. The cathode of diode D4 and the anode of diode D3 are connected to one I / O port and the second I / O port of the image processing chip, respectively. The anode of diode D4 and the cathode of diode D3 are connected to one end of potentiometer RP1. The other end of potentiometer RP1 is connected to an anti-electric ring.

[0020] In practical use, the electrostatic discharge (ESD) detection circuit uses an electric field sensor to detect the electrostatic charge signal in the space where the circuit board is located. This signal is converted into a voltage by a transimpedance amplifier. One voltage path directly enters the ESD discharge circuit, while the other path, calculated by an integrator, enters the ESD discharge circuit after calculating the rate of change of voltage. The voltage is detected by a Zener diode (TVS4). When the voltage is higher than the TVS4's regulated voltage of 1.2V but less than +1.4V, transistor Q1 conducts, and the output voltage is applied to the adjustable terminal of potentiometer RP1. By adjusting the resistance of potentiometer RP1, the electrostatic discharge and discharge signals are controlled. When the voltage exceeds the Zener diode TVS4's regulation voltage by 1.2V and 3.3V, the discharge diode BV1 is activated. The ESD protection diode, suppressing static electricity to ground, discharges through the discharge diode BV1, varistor, and discharge capacitor C7 to ground. Simultaneously, the voltage change rate signal is applied to the base of the discharge diode BV1 via the Zener diode TVS6 and resistor R6 in an inverse-time manner, accelerating the activation of the discharge diode BV1 and ensuring timely discharge to ground. This electrostatic discharge protection circuit is used to protect the input to the image processing chip. The signal of the chip is protected against electrostatic discharge (ESD). Specifically, a ceramic discharge tube (TVS1) is placed between the RGB888 signals of the two interfaces output from the first HDMI receiving circuit to protect the subsequent chips. The RGB888 signals of the two interfaces are connected to ground via transient suppression diodes (TVS3 and TVS2) for ESD protection. The RGB888 signal of one interface is connected to one I / O port of the image processing chip via buffer F1 and grounding capacitor C1. The RGB888 signal of the other interface is connected to the second I / O port of the image processing chip via inverter F2 and grounding capacitor C2. The signal level is adjusted to change the logic level of the RGB888 signal to avoid transmission crosstalk. The negative terminal of diode D4 and the positive terminal of diode D3 are connected to the first I / O port and the second I / O port of the image processing chip, respectively. The positive terminal of diode D4 and the negative terminal of diode D3 are connected to one end of potentiometer RP1. The other end of potentiometer RP1 is connected to an anti-static ring. Diodes D3 and D4 are reversed for conduction protection. The variable resistance of the potentiometer is used to discharge the electrostatic charge through the anti-static ring. The electrostatic charge can be discharged safely and reliably.

[0021] The above description is a further detailed explanation of the present utility model in conjunction with specific embodiments, and it should not be considered that the specific implementation of the present utility model is limited to this. For those skilled in the art to which the present utility model pertains and related fields, any extensions, operation methods, and data substitutions made based on the technical solution concept of the present utility model should fall within the protection scope of the present utility model.

Claims

1. An electrostatic discharge circuit for an ultra-high-definition two-path image divider, comprising a first HDMI receiving circuit and a second HDMI receiving circuit, and an image processing chip, wherein the first HDMI receiving circuit and the second HDMI receiving circuit are connected to the image processing chip respectively, characterized in that, The electrostatic protection circuit is arranged between the first HDMI receiving circuit and the image processing chip, and between the second HDMI receiving circuit and the image processing chip, and the electrostatic detection circuit and the electrostatic release circuit are arranged on the circuit board. The electrostatic detection circuit is connected with the electrostatic protection circuit and the electrostatic release circuit respectively.

2. The electrostatic discharge circuit for an ultra-high definition two-path image divider according to claim 1, wherein The electrostatic detection circuit comprises a capacitor C3, one end of the capacitor C3 is connected with an electrostatic signal detected by an electric field sensor, the other end of the capacitor C3 is connected with one end of a resistor R1, the other end of the resistor R1 is connected with an inverting input terminal of an operational amplifier AR1, one end of a resistor R2 and one end of a capacitor C4 respectively, a non-inverting input terminal of the operational amplifier AR1 is connected with the ground, and an output terminal of the operational amplifier AR1 is connected with the other end of the resistor R2, the other end of the capacitor C4, a negative electrode of a voltage stabilizing tube TVS4 and one end of a resistor R4 respectively, and one end of a capacitor C5, the other end of the resistor R4 is connected with an inverting input terminal of an operational amplifier AR2, one end of a resistor R3 and one end of a capacitor C6 respectively, a non-inverting input terminal of the operational amplifier AR2 is connected with the ground through a resistor R5, and an output terminal of the operational amplifier AR2 is connected with the other end of the resistor R3, the other end of the capacitor C6, a negative electrode of a voltage stabilizing tube TVS6 and one end of a resistor R6 respectively.

3. The electrostatic discharge circuit for an ultra-high definition two-path image divider according to claim 1, wherein The electrostatic release circuit comprises a capacitor C5, a voltage stabilizing tube TVS6 and a resistor R6, the other end of the capacitor C5 is connected with a base of a triode Q1 and a negative electrode of a voltage stabilizing tube TVS5 respectively, an emitter of the triode Q1 is connected with a power supply +1.4V, a collector of the triode Q1 is connected with a positive electrode of an electrolytic capacitor E2 and an adjustable terminal of a potentiometer RP1 respectively, a positive electrode of the voltage stabilizing tube TVS5 is connected with a base of a discharge tube BV1, a positive electrode of the voltage stabilizing tube TVS6, the other end of the resistor R6 and one end of a grounding resistor R7 respectively, a collector of the discharge tube BV1 is connected with a signal from a transient voltage suppression diode TVS to the ground, an emitter of the discharge tube BV1 is connected with an upper end of a first pressure sensitive resistor RT1, and a lower end of the first pressure sensitive resistor RT1 is connected with a pressure sensitive resistor of a second pressure sensitive resistor RT2 and a discharge capacitor C7 to the ground respectively.

4. The electrostatic discharge circuit for an ultrahigh definition two-path image divider according to claim 1, wherein The electrostatic protection circuit comprises ceramic discharge tubes TVS1, TVS2 and TVS3, the ceramic discharge tube TVS1 is arranged between RGB888 signals of two interfaces of an output of the first HDMI receiving circuit, the RGB888 signals of the two interfaces are connected with the ground through transient voltage suppression diodes TVS3 and TVS2 respectively, the RGB888 signals of one of the two interfaces are connected with an IO port of the image processing chip through a buffer F1 and a grounding capacitor C1, the RGB888 signals of the other of the two interfaces are connected with a second IO port of the image processing chip through an inverter F2 and a grounding capacitor C2, a negative electrode of a diode D4 and a positive electrode of a diode D3 are connected with the IO port and the second IO port of the image processing chip respectively, a positive electrode of the diode D4 and a negative electrode of the diode D3 are connected with one end of the potentiometer RP1, and the other end of the potentiometer RP1 is connected with an anti-static ring.

5. The electrostatic discharge circuit for an ultrahigh definition two-path image divider according to claim 1, wherein The image processing chip part of the circuit board is paved with an anti-static coating.

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